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This thesis investigates the uniaxial stress reversal fatigue behavior of plain concrete under low-frequency cyclic loading, with a focus on frequencies below 1 Hz. The research aims to enhance the understanding of the fatigue life of concrete structures, particularly in infrastructure subjected to repeated loading such as dams and bridges. The specimens were tested at three specific frequencies: 0.2 Hz, 0.5 Hz, and 0.75 Hz. These tests were performed under a constant stress range of 11.4 MPa, replicating the stress conditions identified through Finite Element Analysis of a spillway from an existing gravity dam in northern Manitoba. The testing regime set the maximum stress level at 90% of the tensile strength of the concrete and the minimum stress level at 20% of the compressive strength of the concrete. The analysis concentrated on evaluating the fatigue life of concrete, examining maximum strain curves, stiffness degradation, and energy dissipation under stress reversal conditions. The analysis revealed that higher frequencies generally resulted in a longer fatigue life. The maximum strain and stiffness degradation curves exhibited typical S-shaped patterns, indicating progressive damage accumulation in the concrete specimens, and increasing strain at failure. Additionally, stiffness degradation showed negligible differences in deterioration indices between 0.5 Hz and 0.75 Hz, with slightly higher deterioration observed at 0.2 Hz. Energy analysis indicated that higher frequencies result in increased energy dissipation per fatigue cycle. The application of the Weibull distribution effectively modeled the variability in fatigue life data, providing insights into the probabilistic nature of concrete's fatigue behavior under stress reversal loading. Furthermore, the research included a validation of the stress reversal fatigue model proposed by Ferreira et al. (2024). The model's applicability across different frequencies was assessed, demonstrating its potential for

This thesis investigates the uniaxial stress reversal fatigue behavior of plain concrete under low-frequency cyclic loading, with a focus on frequencies below 1 Hz. The research aims to enhance the understanding of the fatigue life of concrete structures, particularly in infrastructure subjected to repeated loading such as dams and bridges. The specimens were tested at three specific frequencies: 0.2 Hz, 0.5 Hz, and 0.75 Hz. These tests were performed under a constant stress range of 11.4 MPa, replicating the stress conditions identified through Finite Element Analysis of a spillway from an existing gravity dam in northern Manitoba. The testing regime set the maximum stress level at 90% of the tensile strength of the concrete and the minimum stress level at 20% of the compressive strength of the concrete. The analysis concentrated on evaluating the fatigue life of concrete, examining maximum strain curves, stiffness degradation, and energy dissipation under stress reversal conditions. The analysis revealed that higher frequencies generally resulted in a longer fatigue life. The maximum strain and stiffness degradation curves exhibited typical S-shaped patterns, indicating progressive damage accumulation in the concrete specimens, and increasing strain at failure. Additionally, stiffness degradation showed negligible differences in deterioration indices between 0.5 Hz and 0.75 Hz, with slightly higher deterioration observed at 0.2 Hz. Energy analysis indicated that higher frequencies result in increased energy dissipation per fatigue cycle. The application of the Weibull distribution effectively modeled the variability in fatigue life data, providing insights into the probabilistic nature of concrete's fatigue behavior under stress reversal loading. Furthermore, the research included a validation of the stress reversal fatigue model proposed by Ferreira et al. (2024). The model's applicability across different frequencies was assessed, demonstrating its potential for

Inertial effects caused by perturbations of dynamical equilibrium during the flow of soft matter constitute a hallmark of turbulence. Such perturbations are attributable to an imbalance between energy storage and energy dissipation. During the flow of Newtonian fluids, kinetic energy can be both stored and dissipated, while the flow of viscoelastic soft matter systems, such as polymer fluids, induces the accumulation of both kinetic and elastic energies. The accumulation of elastic energy causes local stiffening of stretched polymer chains, which can destabilise the flow. Migrating multicellular systems are hugely complex and are capable of self-regulating their viscoelasticity and mechanical stress generation, as well as controlling their energy storage and energy dissipation. Since the flow perturbation of viscoelastic systems is caused by the inhomogeneous accumulation of elastic energy, rather than of kinetic energy, turbulence can occur at low Reynolds numbers. This theoretical review is focused on clarifying the role of viscoelasticity in the appearance of low-Reynolds turbulence. Three types of system are considered and compared: (1) high-Reynolds turbulent flow of Newtonian fluids, (2) low and moderate-Reynolds flow of polymer solutions, and (3) migration of epithelial collectives, discussed in terms of two model systems. The models considered involve the fusion of two epithelial aggregates, and the free expansion of epithelial monolayers on a substrate matrix.

The ATLAS detector is installed in its experimental cavern at Point 1 of the CERN Large Hadron Collider. During Run 2 of the LHC, a luminosity of ℒ = 2 × 1034 cm-2 s-1 was routinely achieved at the start of fills, twice the design luminosity. For Run 3, accelerator improvements, notably luminosity levelling, allow sustained running at an instantaneous luminosity of ℒ = 2 × 1034 cm-2 s-1, with an average of up to 60 interactions per bunch crossing. The ATLAS detector has been upgraded to recover Run 1 single-lepton trigger thresholds while operating comfortably under Run 3 sustained pileup conditions. A fourth pixel layer 3.3 cm from the beam axis was added before Run 2 to improve vertex reconstruction and b-tagging performance. New Liquid Argon Calorimeter digital trigger electronics, with corresponding upgrades to the Trigger and Data Acquisition system, take advantage of a factor of 10 finer granularity to improve triggering on electrons, photons, taus, and hadronic signatures through increased pileup rejection. The inner muon endcap wheels were replaced by New Small Wheels with Micromegas and small-strip Thin Gap Chamber detectors, providing both precision tracking and Level-1 Muon trigger functionality. Trigger coverage of the inner barrel muon layer near one endcap region was augmented with modules integrating new thin-gap resistive plate chambers and smaller-diameter drift-tube chambers. Tile Calorimeter scintillation counters were added to improve electron energy resolution and background rejection. Upgrades to Minimum Bias Trigger Scintillators and Forward Detectors improve luminosity monitoring and enable total proton-proton cross section, diffractive physics, and heavy ion measurements. These upgrades are all compatible with operation in the much harsher environment anticipated after the High-Luminosity upgrade of the LHC and are the first steps towards preparing ATLAS for the High-Luminosity upgrade of the LHC. This paper describes the Run 3 configuration

Auxetic cementitious cellular composites (ACCCs) exhibit desirable mechanical properties (e.g., high fracture resistance and energy dissipation), due to their unique deformation characteristics. In this study, a new type of cementitious auxetic material, referred to as peanut shaped ACCC, has been designed and subsequently architected using additive manufacturing techniques. Two peanut shaped ACCCs specimens with different pseudo-minor axes have been tested under uniaxial compression with Digital Image Correlation (DIC) to assess their compressive behavior, peak strength, Poisson's ratio, and energy dissipation capacity. Additionally, cyclic tests were conducted to investigate their compressive resilience properties, further elucidated through microstructural analysis using a digital optical microscope. The mechanical test results were also compared with those of previously developed elliptical-shaped ACCCs. Furthermore, a numerical model was used to simulate the mechanical behavior of peanut shaped ACCCs under uniaxial compression, and showed a good agreement with the experimental data. The auxetic behavior observed in peanut shaped ACCCs arises from the rotation of sections facilitated by fiber bridging at the ligament of adjacent holes within the cementitious unit cell. In comparison to elliptical-shaped ACCCs, peanut shaped ACCCs can exhibit a slightly more negative Poisson's ratio and mitigate stress concentration. The reduction of stress concentration enables peanut shaped ACCCs to dissipate substantial energy, showcasing enhanced ductility and toughness. In cyclic tests, peanut shaped ACCCs exhibit superior recoverable deformation elasticity, attributed to robust fiber bridging capacity. The exceptional mechanical properties exhibited by peanut shaped ACCCs offer a scalable solution for developing energy-absorbent and multifunctional cementitious materials for smart infrastructure., Materials and Environment

The ultrasonic metal welding technology is widely promoted as a new connection approach in the field of current energy vehicle wiring harness connection. In the present investigation, low-temperature mechanical properties of slotted and normal terminals were studied. The EVR 25 mm2 copper wires are selected for welding using ultrasonic wire harness welding with two different structures of T2 copper terminals. Then, a more stable joint structure under the same welding parameters is investigated through tensile tests at − 30 °C and 25 °C. The results showed that the ST joint has higher static mechanical properties than the NT joint at 25 °C and the peak load of the joint is increased. In addition, the results investigated that the performance and welded interface texture of ST joints is reliable than NT joints under 25 °C, the maximum joint load is increased by 12.93% under − 30 °C, the joint energy absorption is increased by 87.58%, and ST joint stability is better and safer in actual production applications. At the same welding parameters, the ST joints have less neck contraction at 25 °C and the ligamentous sockets are smaller and densely welded surfaces. The failures of ST joints and NT joints are investigated under the same welding parameters. The energy loss during the ST joint welding process is smaller and the welding effect is better and advantageous. The SEM findings showed that the failure of the ST joint and the NT joint is different and the tensile strength of the ST joint is greater under the same low-temperature conditions. © International Institute of Welding 2024.

Stainless steel is a corrosion resistant iron alloy with great potential in structural engineering due to its excellent mechanical features, durability and aesthetic properties. Since most of the existing research has concerned the behaviour of the material, the response of individual structural members, or the performance of simple structural systems under monotonic loading, one of the challenges that remains is the evaluation of the cyclic performance of members to promote its use in seismic design and exploit the excellent ductility and strain hardening properties of this material. For this reason, an experimental programme on austenitic stainless steel Rectangular Hollow Section (RHS) specimens was carried out at the Department of Civil Engineering of the Università degli Studi di Salerno in collaboration with the Universitat Politècnica de Catalunya. A total of eight RHS specimens were tested around the minor axis under both monotonic (three specimens) and cyclic (five specimens) loading, in an experimental set-up that followed a cantilever scheme. The main purpose of this study was to acquire information on the cyclic performance of austenitic steel structural members, focusing on the comparison between monotonic and cyclic behaviours. The outcomes of the tests included the load–displacement and the moment–rotation curves, the energy dissipation capacity, and the evaluation of the key rotation capacities of the members. The reported data are essential to enhance the still scarce research on the seismic behaviour of stainless steel structures., The research was supported by the Spanish Ministry for the Economy and Competitiveness through the Project BIA2016–75678-R, AEI/FEDER, UE “Comportamiento estructural de pórticos de acero inoxidable. Seguridad frente a acciones accidentales de sismo y fuego”. The first author would also acknowledge the financial support received from the Spanish Ministry for Science, Innovation and Universities through the FPI-MINECO PhD fellowship Ref. BES-2017–082958., Peer Reviewed, Postprint (author's final draft)

Miniaturization has emerged as a trend in the last few decades across multiple areas. Lab-on-a-chip devices (for example) are preferred over traditional macroscopic techniques due to their high throughput, fast operation and ease of automation. In general, miniaturization means the dominance of surface forces, therefore, surface wetting is important to these applications; and many others like novel oil separation techniques, processing of metal ores, and the self-cleaning superhydrophobic surfaces. However, our ability to design surfaces tailored to specific applications is hampered by the lack of a quantitative model for the critical wetting parameter of Contact Angle Hysteresis (CAH), being defined as the difference between the advancing and receding (static) contact angles. CAH largely determines liquid mobility when surface forces dominate. Previous wetting models are unable to quantitatively predict CAH on general rough surfaces: The kinematic model suits smoothly undulating surfaces only; the energy minimization model offers qualitative insights; and the energy dissipation model is con- strained by an incomplete understanding of energy dissipation during liquid spreading. The well-known Young, Wenzel and Cassie-Baxter equations only predict a single contact angle instead of a range of stable contact angles as observed experimentally. In this thesis, a predictive wetting model is developed that can be used for predicting CAH on naturally occurring substances as well as for designing functionalised wetting surfaces for specific applications. Numerical simulations of an advancing fluid interface are performed using the open-source program Surface Evolver, with the results interpreted via a mechanical energy balance (MEB) framework to predict CAH from the input parameters of the surface topology and Young’s angle. A complementary experimental study is also performed to measure CAH on surfaces having both periodically distributed and randomly distributed cylindrica

Failure of irregular rock samples may provide implications in the rapid estimation of rock strength, which is imperative in rock engineering practice. In this work, analytical, experimental and numerical investigations were carried out to study the mechanical properties and failure characteristics of rock spheres under paired point loads. Analytical solutions indicted that with the increase in sample size (contact angle) and decrease in Poisson's ratio, the uneven tensile stress in theta direction decreased. Then laboratory experiments were carried out to investigate the load characteristics and failure mode of spherical marble samples with different sizes subjected to a pair of diametral point loads. The discrete element method (DEM) was adopted to study the failure process of rock spheres. The effect of the sphere diameter on the point load contact angle was examined in terms of peak load, crushed zone distribution and energy dissipation. Experimental and numerical results showed that the samples primarily fail in tension, with crushed zones formed at both loading points. With increase in the sample size, the contact angle, crushed area and total work increase. As the specimen diameter increases from 30 mm to 50 mm, the peak load on the specimen increases from 3.6 kN to 8.8 kN, and the percentage of crushed zone (ratio of crushing zone to sample radius, d/r) increased from 0.191 to 0.262. The results of the study have implications for understanding the failure of irregular rock specimens under point loading conditions and their size effects.

Many existing spillways in Sweden are now refurbished for higher discharge capacity than originally constructed for, which calls for improved energy dissipation functions to reduce downstream impacts. The spillway examined belongs to this category, with an increase in design flood by nearly 45%. To attain effective energy dissipation and curtail scouring potential in the tailwater, a new stilling basin is excavated immediately downstream of the spillway piers. Acting as roughness elements, cross-sectional bottom ribs covering the whole width are added to the chute. The element width and height chosen are 0.50 and 0.40 m. Both hydraulic model tests and CFD simulations are performed to explore and optimize the chute flow conditions and assist in the engineering solution. Upon project completion, spillway flood release has seen satisfactory energy dissipation results., QC 20240409 Part of ISBN 9789083347615

Adiabatic quantum-flux-parametron (AQFP) logic is a superconductor logic family that can operate with low switching energy due to adiabatic switching. In a previous study, we proposed a low-latency clocking scheme called delay-line clocking, in which the latency for each logic operation is determined by the propagation delay of the excitation current. We demonstrated several AQFP logic gates with delay-line clocking and demonstrated a phase skipping operation, in which some of the AQFP buffers for phase synchronization are removed to reduce the junction count and energy dissipation. In the present study, we design and demonstrate an AQFP 8-bit ripple carry adder with delay-line clocking to show that delay-line clocking and the phase skipping operation are applicable to large-scale AQFP circuits. The latency of this adder is 960 ps, which is 40% of that for a conventional design. Moreover, due to the phase skipping operation, the junction count is reduced to approximately 70% of that for the conventional design. We find that this adder can operate at up to 4 GHz. The above results indicate that large-scale AQFP circuits can operate with low latency and low junction count by using delay-line clocking and a phase skipping operation.

The hysteretic behavior of bolt connections in a timber-concrete composite (TCC) bridge was investigated. Six identical TCC specimens were designed with bolted connections and subjected to reversed cyclic loading tests. The failure modes, energy dissipation capacity, stiffness degradation, strength degradation, and hysteretic responses of the specimens were evaluated. The experimental results indicate that the predominant failure mode was a dual-hinge mechanism in the bolts of the TCC specimens. The TCC specimens exhibited satisfactory energy dissipation and achieved a mean ductility factor of 6.76. A finite-element model was developed to simulate the cyclic response of the tested TCC specimens. The simulated data are in good agreement with the experimental data. The experimental and numerical results reported are useful for the development of design guidelines for TCC bridges with bolted connections., QC 20221212

Understanding the deformation mechanisms and the impact forces generated by landslides on structures is essential for risk assessment and improving the design of mitigation measures. This thesis studies the effect of different basal sliding characteristics of biplanar compound landslides on the post-failure mechanics and the interaction with rigid structures. The Material Point Method (MPM), an advanced numerical tool capable of simulating large deformations, captures the whole instability and the impact process. A simple geometry of a biplanar compound landslide is considered with two different types of biplanar slope transitions along the basal surface – sharp transition (or "kink" geometry) and curved transition (with different radii). A comprehensive parametric study with more than 280 simulations is performed to analyze the landslide post-failure behavior in terms of the radii of transition, the basal friction angle, the distance to the rigid wall, the roughness of the rigid wall, and the scale of the landslide. The results are presented in terms of maximum impact force on the rigid wall and final runout (in the absence of the wall). Results show that the basal characteristics impact the landslide kinetics and energy dissipations, which in turn, influence the impact forces on the rigid wall as well as the final runout of the landslide. The basal friction amplifies the influence of slope geometry on maximum impact forces. In addition, the maximum impact force from numerical results is compared with the predictions from existing semi-empirical approaches. Finally, a preliminary empirical framework is proposed to incorporate the effects of basal sliding characteristics of compound landslides into predicting impact forces on retaining walls.

Knots are ubiquitous in nature and engineering structures. Fundamental mechanics and topology of knots have been intensively studied in the past. In this thesis, we introduce a novel mechanical design based on slipknots that are lightweight, energy-dissipative, junction free and resettable. The slipknot dissipates the input mechanical energy using friction, which will be discussed in detail. We report the design and energy dissipation performance of a 2D mesh, which is compared to a control mesh constructed using normal knots. Furthermore, extending this idea to the realm of robotics and the challenging task of perching, we attempt to provide a solution using our design that is easy to construct and use. We report a bio-inspired shooting and manipulating mechanism using slipknots, based on the chameleon tongue and its impressive shooting motion used to catch prey. We found that the perching and shooting motion can be further optimized by introducing a latch into the system, which allows us to amplify the output power. We hope this study opens up a portal to a new world of structures that use knots to tackle age-old problems.

To study the shear deformation and failure characteristics of a wellbore and the interaction mechanism with its surrounding rocks induced by a layer slip during natural gas hydrates (NGHs) extraction, this paper conducted a numerical simulation study of wellbore shear induced by a layer slip using ABAQUS software and carried out a laboratory experiment of wellbore shear to verify the accuracy of the numerical model. The results show that the shear force–displacement curves obtained from the laboratory experiments and numerical simulations are consistent with five stages, including the compaction stage, linear stage, plastic stage, strain-softening stage and residual stage. The wellbore shows a “Z”-shaped deformation characteristic after its shear breakage. The shear force of the wellbore is maximum at the shear surface, and it is distributed in an approximate “M” shape along the shear surface. The axial force of the wellbore is small and uniformly distributed in the initial stage of the shear. The wellbore bending moment is minimum at the shear surface, with a value of 0, and it is distributed in a skew–symmetric wave shape along the shear surface. During the shearing, the evolution of the wellbore axial force and shear force can be classified into the distribution pattern along the radial direction on the shear surface and the pattern along the axial direction. The combination of the wellbore axial force and shear force causes the tensile–shear compound failure of the wellbore. During shearing, the wellbore and rock body gradually enter the plastic state with the increase in the shear displacement. When the entire cross-section of the wellbore is in the plastic state, a “necking” phenomenon of the wellbore begins to appear. During the shearing, the frictional dissipation energy and plastic dissipation energy increase constantly. In addition, the elastic strain energy increases to a peak and then decreases to a certain value, which remains unchanged along with the w, Journal of Marine Science and Engineering, 11(4), art. no. 837; 2023

Aircraft designed for naval aircraft carriers experience great airframe stress during landing due to the high vertical velocities that they must maintain as a consequence of the extremely short runway and shallow landing angle of attack. This creates a need for structural rigidity to counteract the forces that land-based aircraft never experience. This is not ideal if it otherwise limits the performance and flying capabilities of the aircraft that are otherwise necessary for the environments they might find themselves in. As such, a new approach to protecting the aircraft from the immense loads they experience during landing could be to add flexibility to the airframe and landing gear, promoting deflection instead of failure. This thesis aims to investigate this idea, starting with an elementary set of tests, looking into material flexibility, and then moving on to adding this concept to progressively more advanced structural systems. Using balls of varying material, preliminary drop tests indicated that material flexibility could assist the dissipation of landing energies, showing that the coefficient of restitution increases with the stiffness. Drop tests involving mass-spring-damper systems as well as cantilever plates and transverse beams also indicated that the strain energy a body can absorb from a set load case can be increased if its flexibility also grows. This finding led to the important conclusion and finding that a flexible body can transfer and store at least 10 times its initial contribution of energy to a system in the form of strain energy. Through these tests, it was shown that flexible structures can be a beneficial design feature in combatting and dissipating vertical landing energies.

A spillway is a crucial dam structure that regulates water levels and prevents the dam from overtopping. The majority of the dams in the world were constructed before the 1980s. Compared to the current design flood standards, many spillways are undersized, e.g., in Sweden. The higher floods also change the air-water flow properties, giving rise to risks in spillway operations. High-velocity flow is a major concern in spillway design. If the flow rate exceeds 20 m/s, there is a risk of cavitation. Another issue connected with the increased floods is energy dissipation. Many existing energy-dissipating arrangements are insufficient or constructed only for a design flood standard at the time of dam construction. To this end, it is essential to assess the discharge behaviors of spillways, including discharge capacity, two-phase flow features, energy dissipation, cavitation, etc. Engineering solutions for improved hydraulic performance are also critical to ensure safe operation. This thesis focuses on CFD and data-driven modeling for safe spillway discharge, presenting new insights into spillway hydraulics, improved methods for accurate flow predictions, and structural modifications for better hydraulic performance. The research consists of five parts. (1) For discharge estimation, ensemble learning models are established to forecast the river flows, aiming to provide accurate inflow information, even multiple days ahead. To directly assess spillway discharge capacity, three data-driven models are constructed, which yield accurate flow predictions and outperform empirical correlations. (2) For modified designs, several unconventional step layouts are conceived, with their hydraulic behaviors investigated. The modified configurations include steps with chamfers and cavity blockages and inclined steps. The goal is to devise engineering solutions to enhance energy dissipation and reduce cavitation risks. (3) For improved two-phase flow modeling, a population balance model i, Ett utskovsparti är en viktig del av en dammanläggning eftersom det reglerar avbördning och uppströmsvattenstånd samt förhindrar överströmning. Majoriteten av vattenkraftsdammarna i världen byggdes före 1980-talet och i förhållande till gällande dimensionerande kriterier är många befintliga utskov underdimensionerade. Ökad avbördning förändrar också luftinblandningsproblematiken i vattenvägen, vilket ger upphov till risker relaterade till utskovens funktion. Hög vattenhastighet vid avbördning är ett bekymmer vid utformning av vattenvägen. Om hastigheten överstiger 20 m/s finns risk för kavitation, vilket är ett problem som påverkar många dammar i Sverige. En annan frågeställning kopplad till ökad utskovsavbördning är energiomvandling. Många befintliga energiomvandlare är otillräckliga eller endast utformade för en lägre dimensionerande standard, giltig då dammarna byggdes. För att rätta till dessa problem är det nödvändigt att noggrant utvärdera avbördningsegenskaperna hos utskov, inklusive avbördningskapacitet, tvåfasströmning, energiomvandlingsfunktion, kavitation, etc. Tekniska lösningar för förbättrad hydraulisk prestanda är också avgörande för att garantera säker drift av dammanläggningar. Med fokus på CFD och datadrivna metoder baserade på nya insikter i avbördningsmodellering presenteras i denna avhandling förbättrade metoder för prediktering av utskovsströmningar och föreslag på strukturella anpassningar för ökad hydraulisk prestanda. Forskningen består av fem delar. (1) För uppskattning av flöden i en älv upprättas olika maskininlärningsmodeller. Syftet är att tillhandahålla korrekta inflödesuppgifter, även på flera dagars sikt. För att bestämma avbördningskapacitet hos utskov utvecklas tre datadrivna modeller vilka ger flödesprognoser som överträffar de som kan fås med empiriska korrelationer. (2) För att förbättra hydrauliska beteenden undersöks flera okonventionella utformningar hos s.k. "stepped spillways", i vilka ingår steg med avfasning, hålrumsbloc, QC 20230516

Architected materials exhibit extraordinary properties in comparison with conventional materials and structures, resulting in additional functionality and efficiency by engineering the geometry in harmony with the base material. Buckling-induced architected materials (BIAMs) are a class of architected materials that exhibit a significant potential to absorb and dissipate energy owing to their local instabilities. Previous studies have shown a trade-off between energy dissipation and geometrical recoverability in metallic BIAM, which limits their use in applications that require both of these features. This study, for the first time, presents 4D printing of buckling-induced architected iron-based shape memory alloys (BIA Fe-SMAs) using laser powder bed fusion (LPBF). The results show that 4D printing of BIA Fe-SMAs can offer both energy dissipation and geometrical recoverability (i.e., recentring). The study was conducted on two different alloy compositions of Fe-17Mn-5Si-10Cr-4Ni. Quasi-static cyclic tests were performed on the two BIA Fe-SMAs, and the samples were subsequently heated to 200 °C to activate the shape memory effect (SME) of the base material. The samples could recover the residual deformations accumulated during the cyclic load owing to the SME of the base material, which led to shape-recovery ratios of 96.8 and 98.7% for the studied BIA Fe-SMAs. The results of this study demonstrate that 4D printing of BIA Fe-SMAs can yield an enhanced multi-functional behavior by combining the material's inherent functional behavior with the functionalities of the architected structure. Notably, BIA Fe-SMA samples could reconfigure their initial shape without damage after densification, which sets them apart from conventional crushable lattices.

One of the most obvious characteristics of spillways is their energy consumption, which has been extensively researched to understand how to estimate and increase it. Among these spillways, stepped spillways exhibit significant energy consumption potential compared to other types due to the artificial roughness of the bed. In this study, hydraulic modeling of the baffled stepped spillway in three dimensions and the two-phase flow system was conducted using FLOW-3D software. The results obtained were then compared with relevant laboratory experiments. Upon examining the modeling results, it was observed that the unique shape of the blocks in the aforementioned structure led to an increase in flow irregularity, resulting in a 77% reduction in flow energy. The proximity of the numerical model's results to the experimental model (RMSE=0.02) indicates that numerical methods can effectively simulate hydraulic behavior. Overall, it can be concluded that numerical methods are well-suited for accurately simulating hydraulic behavior.

Adiabatic quantum-flux-parametron (AQFP) logic is a superconductor logic family that can operate with low switching energy due to adiabatic switching. In a previous study, we proposed a low-latency clocking scheme called delay-line clocking, in which the latency for each logic operation is determined by the propagation delay of the excitation current. We demonstrated several AQFP logic gates with delay-line clocking and demonstrated a phase skipping operation, in which some of the AQFP buffers for phase synchronization are removed to reduce the junction count and energy dissipation. In the present study, we design and demonstrate an AQFP 8-bit ripple carry adder with delay-line clocking to show that delay-line clocking and the phase skipping operation are applicable to large-scale AQFP circuits. The latency of this adder is 960 ps, which is 40% of that for a conventional design. Moreover, due to the phase skipping operation, the junction count is reduced to approximately 70% of that for the conventional design. We find that this adder can operate at up to 4 GHz. The above results indicate that large-scale AQFP circuits can operate with low latency and low junction count by using delay-line clocking and a phase skipping operation.

To study the shear deformation and failure characteristics of a wellbore and the interaction mechanism with its surrounding rocks induced by a layer slip during natural gas hydrates (NGHs) extraction, this paper conducted a numerical simulation study of wellbore shear induced by a layer slip using ABAQUS software and carried out a laboratory experiment of wellbore shear to verify the accuracy of the numerical model. The results show that the shear force–displacement curves obtained from the laboratory experiments and numerical simulations are consistent with five stages, including the compaction stage, linear stage, plastic stage, strain-softening stage and residual stage. The wellbore shows a “Z”-shaped deformation characteristic after its shear breakage. The shear force of the wellbore is maximum at the shear surface, and it is distributed in an approximate “M” shape along the shear surface. The axial force of the wellbore is small and uniformly distributed in the initial stage of the shear. The wellbore bending moment is minimum at the shear surface, with a value of 0, and it is distributed in a skew–symmetric wave shape along the shear surface. During the shearing, the evolution of the wellbore axial force and shear force can be classified into the distribution pattern along the radial direction on the shear surface and the pattern along the axial direction. The combination of the wellbore axial force and shear force causes the tensile–shear compound failure of the wellbore. During shearing, the wellbore and rock body gradually enter the plastic state with the increase in the shear displacement. When the entire cross-section of the wellbore is in the plastic state, a “necking” phenomenon of the wellbore begins to appear. During the shearing, the frictional dissipation energy and plastic dissipation energy increase constantly. In addition, the elastic strain energy increases to a peak and then decreases to a certain value, which remains unchanged along with the w, Journal of Marine Science and Engineering, 11(4), art. no. 837; 2023

The split Hopkinson pressure bar (SHPB) is a widely used method for analyzing the strength-strain characteristics of wood materials [1]. Experiments show that, as wood is a relatively soft material and the experimental setup is limited in size, the entire wave is not fully recorded before it is mixed with waves reflected from the ends. To be able to analyze how much energy is dissipated in a deformation process, it is required that the whole wave be recorded. In the present investigation, the pressure tail was reconstructed theoretically in the incident bar using the data from the transmission bar, which should allow for a reduction in the error in the energy of the waves. When a deformation wave propagates along bars, part of its energy dissipates into the environment. In this study, a modification of the SHPB was proposed to calculate and analyze the amount of energy the system loses, not due to the sample. Formulas for energy and momentum equilibrium were used [2]. The influence of the length of the striker and the level of input energy were also analyzed. In the presented experiment, all energy tails were completely recorded. This allowed for the theoretical reconstruction of the tail and a comparison with the recorded one. The pressure tail in the transmitted wave was manually shortened and replaced with a theoretical tail. The theoretical tail was created by performing an exponential curve fit with points from the tail up to the point where it had been shortened. The results show that only about 10% of the tail needs to be registered to accurately reconstruct it. When a registered wave is replaced with a reconstructed one, the resulting error in the total wave's energy value is no greater than 0.3% for a 500mm striker and 1.5% for a 250mm striker.

Broadcasting, which is an essential mode of operation in wireless sensor networks (WSNs), dissipates a non-negligible portion of the energy budget of a sensor node. Broadcasting is achieved by the dissemination of broadcast packets (originated at the BS) by a set of relay nodes, which constitute a backbone so that all sensor nodes receive broadcast packets. Utilization of multiple backbones is necessary to achieve balanced energy dissipation of sensor nodes in broadcasting. In this study, we propose two mixed integer programming (MIP) models (i.e., the flow-based model and the node-based model), which minimize the energy dissipation of the highest energy-consuming node for broadcasting by utilizing multiple backbones. Balanced energy minimization and delay minimization objectives are integrated through a goal programming (GP) framework built upon the foundation provided by the scalable node-based model. Performance evaluations based on the optimal solutions of our models reveal that maximum energy dissipation and delay in WSN broadcasting can be significantly reduced, simultaneously, by utilizing multiple backbones (e.g., with two backbones maximum energy dissipation and delay can be, concurrently, reduced by more than 2% and 22%, respectively, in comparison to the single backbone case, likewise, it is also possible to simultaneously reduce maximum energy dissipation and delay more than 8% and 13%, respectively, depending on the priorities assigned to the objectives). Nevertheless, employing more than two backbones does not provide any significant performance improvements. © 2023 Elsevier B.V., Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK, Busra Gultekin was supported by TÜBİTAK BİDEB 2210 Scholarship Programme, Turkey .

To address the ever-growing connectivity demand in communications, the adoption of ingenious solutions, such as utilization of unmanned aerial vehicles (UAVs) as mobile base stations, is imperative. In general, the location of a UAV base station (UAV-BS) is determined by optimization algorithms, which have high computationally complexities and are hard to run on UAVs due to energy consumption and time constraints. In this article, we overview the UAV-BS trajectory optimization problem for next generation wireless networks and show that a convolutional neural network (CNN) model can be trained to infer the location of a UAV-BS in real time. To this end, we create a framework to determine the UAV-BS locations considering the deployment of mobile users (MUs) to generate labels by using the data obtained from an optimization algorithm. Performance evaluations reveal that once the CNN model is trained with the given labels and locations of MUs, the proposed approach is, indeed, capable of approximating the results given by the adopted optimization algorithm with high fidelity, outperforming reinforcement learning-based approaches in resource-constrained settings. We also explore future research challenges and highlight key issues.

Hypothesis: When a droplet starts sliding on a solid surface, the droplet-solid friction force develops in a manner comparable to the solid-solid friction force, showing a static regime and a kinetic regime. Today, the kinetic friction force that acts on a sliding droplet is well-characterized. But the mechanism underlying the static friction force is still less understood. Here we hypothesize that we can further draw an analogy between the detailed droplet-solid and solid-solid friction law, i.e., the static friction force is contact area dependent. Methods: We deconstruct a complex surface defect into three primary surface defects (atomic structure, topographical defect, and chemical heterogeneity). Using large-scale Molecular Dynamics simulations, we study the mechanisms of droplet-solid static friction forces induced by primary surface defects. Findings: Three element-wise static friction forces related to primary surface defects are revealed and the corresponding mechanisms for the static friction force are disclosed. We find that the static friction force induced by chemical heterogeneity is contact line length dependent, while the static friction force induced by atomic structure and topographical defect is contact area dependent. Moreover, the latter causes energy dissipation and leads to a wiggle movement of the droplet during the static-kinetic friction transition.

This work addresses the contribution of the wavelength composition of the spectrum of the rail support stiffness profile to the expected long-term settlement. To that aim, purely harmonic stiffness variations of different wavelength are studied. The frequency-domain model with a double periodicity level previously developed by the first and last authors is adopted to embed the stiffness profile in one of the periodicity layers. Additional resonance velocities at which the resonance frequency of the track system coincides with the support-passing frequency or its multiples are found. The susceptibility to degradation is assessed both by quantifying the mechanical energy dissipated in the substructure under a moving train axle within one wavelength of the support stiffness variation, and the work performed by the wheel-rail contact force. It is shown that shorter wavelengths and larger standard deviations of varying ballast/subgrade stiffness result in an increasing energy dissipation in the substructure, and increase the work performed by the wheel-rail contact force, therefore leading to a reduced lifetime of the track. The energetic quantities increase for lower mean values of the stiffness profile, confirming the proneness of tracks on soft soils to degradation. The influence of varying stiffness vanishes for wavelengths of approximately 16 times the sleeper span, which is equivalent to a track length of about 10 m. High railpad stiffness values result in increased energy dissipation but the influence is limited. In general, an increasing train velocity amplifies the rate of track degradation, with no stabilizing trend in the high-speed regime (300 km/h)., Mechanics and Physics of Structures

An extension of a recently developed quasi-2D flow model for fluid transients in viscoelastic pipes to handle fluid–structure interaction mechanisms is presented. In a context in which the fluid flow is devised as a structured pseudo-mixture and the pipe's viscoelasticity is rooted in an internal variable theory, the axial movement of the pipe wall is allowed to occur, giving rise to friction, Poisson, and junction coupling mechanisms. The resulting governing equations of the model form a quasi-linear hyperbolic system of partial differential equations, which approximated solution is achieved by means of the method of characteristics. The proposed approach is validated against pressure traces acquired from a reservoir–pipe–valve experimental setup found in the literature. In the course of the validating process, different pipe anchoring conditions are employed to study the system responses. Focus is given to pipe–fluid interface interactions, energy dissipation, and transfer of energy between both media.

Understanding the underlying hydrodynamics and developing strategies to control bouncing droplets on superhydrophobic surfaces are of fundamental and practical significance. While recent efforts have mainly focused on regulating the contact time of bouncing droplets, less attention was given to manipulating droplet rebound from the perspective of energy optimization, which determines the long-term successive dynamics. Here, we investigate the impact of water droplets on superhydrophobic cones at low Weber numbers, where ideally complete rebounds arise. In sharp contrast to flat superhydrophobic surfaces, an impinging droplet on a cone-shaped superhydrophobic surface undergoes almost inversion-symmetric spreading and retracting processes with prolonged contact time, and more strikingly, it rebounds with a higher restitution coefficient. Such enhanced droplet rebound is beyond the prediction of existing theoretical models, in which the viscous boundary layer was recognized as the dominant channel of energy dissipation and, thus, an increase in the contact time would result in a lower restitution coefficient; nevertheless, numerical simulations have confirmed the increase in the restitution coefficient. The quantitative energy and flow field analyses of our numerical results reveal that the suppression of the boundary layer in early impact and the weakening of the viscous flow near the moving edge in the subsequent impact phases, which were not accounted for yet in existing theoretical models, are the causes for the enhancement of droplet rebound on superhydrophobic cones.

A spillway is a crucial dam structure that regulates water levels and prevents the dam from overtopping. The majority of the dams in the world were constructed before the 1980s. Compared to the current design flood standards, many spillways are undersized, e.g., in Sweden. The higher floods also change the air-water flow properties, giving rise to risks in spillway operations. High-velocity flow is a major concern in spillway design. If the flow rate exceeds 20 m/s, there is a risk of cavitation. Another issue connected with the increased floods is energy dissipation. Many existing energy-dissipating arrangements are insufficient or constructed only for a design flood standard at the time of dam construction. To this end, it is essential to assess the discharge behaviors of spillways, including discharge capacity, two-phase flow features, energy dissipation, cavitation, etc. Engineering solutions for improved hydraulic performance are also critical to ensure safe operation. This thesis focuses on CFD and data-driven modeling for safe spillway discharge, presenting new insights into spillway hydraulics, improved methods for accurate flow predictions, and structural modifications for better hydraulic performance. The research consists of five parts. (1) For discharge estimation, ensemble learning models are established to forecast the river flows, aiming to provide accurate inflow information, even multiple days ahead. To directly assess spillway discharge capacity, three data-driven models are constructed, which yield accurate flow predictions and outperform empirical correlations. (2) For modified designs, several unconventional step layouts are conceived, with their hydraulic behaviors investigated. The modified configurations include steps with chamfers and cavity blockages and inclined steps. The goal is to devise engineering solutions to enhance energy dissipation and reduce cavitation risks. (3) For improved two-phase flow modeling, a population balance model i, Ett utskovsparti är en viktig del av en dammanläggning eftersom det reglerar avbördning och uppströmsvattenstånd samt förhindrar överströmning. Majoriteten av vattenkraftsdammarna i världen byggdes före 1980-talet och i förhållande till gällande dimensionerande kriterier är många befintliga utskov underdimensionerade. Ökad avbördning förändrar också luftinblandningsproblematiken i vattenvägen, vilket ger upphov till risker relaterade till utskovens funktion. Hög vattenhastighet vid avbördning är ett bekymmer vid utformning av vattenvägen. Om hastigheten överstiger 20 m/s finns risk för kavitation, vilket är ett problem som påverkar många dammar i Sverige. En annan frågeställning kopplad till ökad utskovsavbördning är energiomvandling. Många befintliga energiomvandlare är otillräckliga eller endast utformade för en lägre dimensionerande standard, giltig då dammarna byggdes. För att rätta till dessa problem är det nödvändigt att noggrant utvärdera avbördningsegenskaperna hos utskov, inklusive avbördningskapacitet, tvåfasströmning, energiomvandlingsfunktion, kavitation, etc. Tekniska lösningar för förbättrad hydraulisk prestanda är också avgörande för att garantera säker drift av dammanläggningar. Med fokus på CFD och datadrivna metoder baserade på nya insikter i avbördningsmodellering presenteras i denna avhandling förbättrade metoder för prediktering av utskovsströmningar och föreslag på strukturella anpassningar för ökad hydraulisk prestanda. Forskningen består av fem delar. (1) För uppskattning av flöden i en älv upprättas olika maskininlärningsmodeller. Syftet är att tillhandahålla korrekta inflödesuppgifter, även på flera dagars sikt. För att bestämma avbördningskapacitet hos utskov utvecklas tre datadrivna modeller vilka ger flödesprognoser som överträffar de som kan fås med empiriska korrelationer. (2) För att förbättra hydrauliska beteenden undersöks flera okonventionella utformningar hos s.k. "stepped spillways", i vilka ingår steg med avfasning, hålrumsbloc, QC 20230516

Using experiments and numerical simulations, we investigate the spontaneous spreading of droplets of aqueous glycerol (Newtonian) and aqueous polymer (shear-thinning) solutions on smooth surfaces. We find that in the first millisecond the spreading of the shear-thinning solutions is identical to the spreading of water, regardless of the polymer concentration. In contrast, aqueous glycerol solutions show a different behavior, namely, a significantly slower spreading rate than water. In the initial rapid spreading phase, the dominating forces that can resist the wetting are inertial forces and contact-line friction. For the glycerol solutions, an increase in glycerol concentration effectively increases the contact-line friction, resulting in increased resistance to wetting. For the polymeric solutions, however, an increase in polymer concentration does not modify contact-line friction. As a consequence, the energy dissipation at the contact line cannot be controlled by varying the amount of additives for shear-thinning fluids. The reduction of the spreading rate of shear-thinning fluids on smooth surfaces in the rapid-wetting regime can only be achieved by increasing solvent viscosity. Our results have implications for phase-change applications where the control of the rapid spreading rate is central, such as anti-icing and soldering.

This work presents a fluid transient model capable of handling the viscoelastic behavior of the pipe. A previously developed quasi-2D flow model is employed as a base, and the viscoelastic behavior of the pipe is incorporated by considering constitutive equations formulated in a thermodynamically consistent framework of an internal variable theory. Such an approach straightforwardly provides expressions for computing the rates of energy dissipation in the fluid and pipe accurately and separately. This novel feature discerns the local and overall impacts of the energy dissipation on the pressure oscillations caused by each medium. The governing equations of the model form a hyperbolic system of partial differential equations whose approximated solutions are obtained by the method of characteristics. Taking as reference pressure signals obtained by a classic reservoir-pipe-valve experiment found in the literature, it is shown that the model predictions are fully consistent. A comparison between the pressure responses of viscoelastic and elastic pipes reveals that in addition to delaying the pressure oscillations, the viscoelastic behavior causes a faster attenuation of them. The rates of energy dissipation in the viscoelastic pipe attain significant magnitudes during the first moments of the fluid transient and alters the hydrodynamical behavior of the flow. Such interference is exposed by comparing the responses of the same experimental setup when two different viscoelastic pipe materials are considered. It is also shown that the knowledge of the parcels of energy dissipated in the fluid and pipe individually can improve the comprehension of the phenomenon and be utilized for theoretical and applied research in the field.

This paper provides experimental data on the temperature rise during granular flows in a small-scale rotating drum due to heat generation. All heat is believed to be generated by conversion of some mechanical energy, through mechanisms such as friction and collisions between particles and between particles and walls. Particles of different material types were used, while multiple rotation speeds were considered, and the drum was filled with different amounts of particles. The temperature of the granular materials inside the rotating drum was monitored using a thermal camera. The temperature increases at specific times of each experiment are presented in form of tables, along with the average and standard deviation of the repetitions of each setup configuration. The data can be used as a reference to set the operating conditions of rotating drums, in addition to calibrating numerical models and validating computer simulations., This project is funded through Marie SKŁODOWSKA-CURIE Innovative Training Network MATHEGRAM1, the People Programme (Marie SKŁODOWSKA-CURIE Actions) of the European Union's Horizon 2020 Programme H2020 under REA grant agreement No. 813202. Dr. Franci acknowledges the support from MCIN/AEI/10.13039/501100011033 and FEDER Una manera de hacer Europa for funding his work via project PID2021-122676NB-I00. Prof. Oñate acknowledges the Severo Ochoa Programme through the Grant CEX2018-000797-S funded by MCIN/AEI/10.13039/501100011033., Peer Reviewed, Postprint (published version)

When designing crash absorber particles for application as a filling material in the double-hull of ships, the main goal is to achieve an optimal mechanical performance, in combination with a low-density particle structure, while fulfilling several additional requirements regarding, for example, non-toxic and hydrophobic behavior. In this study, a fluidized bed was used to coat Poraver® glass particles with Candelilla wax and silicone to attain these specifications. A uniform coating was achieved with wax, but the process turned out to be far more challenging when using silicone. To evaluate the suitability of coated particles as a granular filling material, and to compare their performances with that of untreated Poraver® particles, several mechanical tests, as well as structural investigations, were conducted. While no notable improvement in mechanical behavior was observed on the single-particle level, bulk tests showed promising results regarding compressibility and abrasion resistance of coated particles compared to untreated ones., When designing crash absorber particles for application as a filling material in the double-hull of ships, the main goal is to achieve an optimal mechanical performance, in combination with a low-density particle structure, while fulfilling several additional requirements regarding, for example, non-toxic and hydrophobic behavior. In this study, a fluidized bed was used to coat Poraver® glass particles with Candelilla wax and silicone to attain these specifications. A uniform coating was achieved with wax, but the process turned out to be far more challenging when using silicone. To evaluate the suitability of coated particles as a granular filling material, and to compare their performances with that of untreated Poraver® particles, several mechanical tests, as well as structural investigations, were conducted. While no notable improvement in mechanical behavior was observed on the single-particle level, bulk tests showed promising results regarding compressibility and abrasion resistance of coated particles compared to untreated ones.

X-braced Frames(XBFs), one of the most prevalent lateral load-resisting structures, has low energy dissipation and ductility. This study investigates the behavior of a single-story, single-span X-braced frame equipped with a Vertical Link Beam (XBF-VLB) under monotonic and cyclic loading using the nonlinear finite element technique in the Abaqus software and validated with experimental data. The VLBs were positioned where the bracing members were connected to the beam in double, single, and wide forms. The impacts of the length, depth, and the number of links, stiffeners, and other VLB section parameters were assessed. The A36 steel ductile damage method (DDM) estimated the damage of the main structural members, such as bracing members. The results revealed that X-braced frames with single, double, and wide form Vertical Link Beams (XBF-VLBs) performed better under cyclic and monotonic loading than X-braced frames without Vertical Link Beam (XBFs). Likewise, because the bracing members did not buckle in the XBF-VLB specimens, there was no rapid loss in the stiffness and strength of the X-braced frames. Also, the results of the cyclic loading of the XBF-VLB specimens demonstrated that no rapid drop in stiffness or strength was detected due to no buckling of the bracing members under the cyclic loading, as was the case with the monotonic loading. Additionally, compared to the XBF specimens, the drifts corresponding to the first plastic hinges of the XBF-VLB specimens show that the bracing members experienced nonlinear deformation at greater drifts, with the plastic hinges created in them at bigger displacements. According to the cyclic loading results, the VLB also reduced Von Mises stress and damage in the bracing members of the XBF-VLB specimens. Moreover, the ultimate von Mises stress reduction in the bracing members of the models with VLBs equals 33%, which prevents buckling.

X-braced Frames(XBFs), one of the most prevalent lateral load-resisting structures, has low energy dissipation and ductility. This study investigates the behavior of a single-story, single-span X-braced frame equipped with a Vertical Link Beam (XBF-VLB) under monotonic and cyclic loading using the nonlinear finite element technique in the Abaqus software and validated with experimental data. The VLBs were positioned where the bracing members were connected to the beam in double, single, and wide forms. The impacts of the length, depth, and the number of links, stiffeners, and other VLB section parameters were assessed. The A36 steel ductile damage method (DDM) estimated the damage of the main structural members, such as bracing members. The results revealed that X-braced frames with single, double, and wide form Vertical Link Beams (XBF-VLBs) performed better under cyclic and monotonic loading than X-braced frames without Vertical Link Beam (XBFs). Likewise, because the bracing members did not buckle in the XBF-VLB specimens, there was no rapid loss in the stiffness and strength of the X-braced frames. Also, the results of the cyclic loading of the XBF-VLB specimens demonstrated that no rapid drop in stiffness or strength was detected due to no buckling of the bracing members under the cyclic loading, as was the case with the monotonic loading. Additionally, compared to the XBF specimens, the drifts corresponding to the first plastic hinges of the XBF-VLB specimens show that the bracing members experienced nonlinear deformation at greater drifts, with the plastic hinges created in them at bigger displacements. According to the cyclic loading results, the VLB also reduced Von Mises stress and damage in the bracing members of the XBF-VLB specimens. Moreover, the ultimate von Mises stress reduction in the bracing members of the models with VLBs equals 33%, which prevents buckling.

X-braced Frames(XBFs), one of the most prevalent lateral load-resisting structures, has low energy dissipation and ductility. This study investigates the behavior of a single-story, single-span X-braced frame equipped with a Vertical Link Beam (XBF-VLB) under monotonic and cyclic loading using the nonlinear finite element technique in the Abaqus software and validated with experimental data. The VLBs were positioned where the bracing members were connected to the beam in double, single, and wide forms. The impacts of the length, depth, and the number of links, stiffeners, and other VLB section parameters were assessed. The A36 steel ductile damage method (DDM) estimated the damage of the main structural members, such as bracing members. The results revealed that X-braced frames with single, double, and wide form Vertical Link Beams (XBF-VLBs) performed better under cyclic and monotonic loading than X-braced frames without Vertical Link Beam (XBFs). Likewise, because the bracing members did not buckle in the XBF-VLB specimens, there was no rapid loss in the stiffness and strength of the X-braced frames. Also, the results of the cyclic loading of the XBF-VLB specimens demonstrated that no rapid drop in stiffness or strength was detected due to no buckling of the bracing members under the cyclic loading, as was the case with the monotonic loading. Additionally, compared to the XBF specimens, the drifts corresponding to the first plastic hinges of the XBF-VLB specimens show that the bracing members experienced nonlinear deformation at greater drifts, with the plastic hinges created in them at bigger displacements. According to the cyclic loading results, the VLB also reduced Von Mises stress and damage in the bracing members of the XBF-VLB specimens. Moreover, the ultimate von Mises stress reduction in the bracing members of the models with VLBs equals 33%, which prevents buckling.

One of the most obvious characteristics of spillways is their energy consumption, which has been extensively researched to understand how to estimate and increase it. Among these spillways, stepped spillways exhibit significant energy consumption potential compared to other types due to the artificial roughness of the bed. In this study, hydraulic modeling of the baffled stepped spillway in three dimensions and the two-phase flow system was conducted using FLOW-3D software. The results obtained were then compared with relevant laboratory experiments. Upon examining the modeling results, it was observed that the unique shape of the blocks in the aforementioned structure led to an increase in flow irregularity, resulting in a 77% reduction in flow energy. The proximity of the numerical model's results to the experimental model (RMSE=0.02) indicates that numerical methods can effectively simulate hydraulic behavior. Overall, it can be concluded that numerical methods are well-suited for accurately simulating hydraulic behavior.

Broadcasting, which is an essential mode of operation in wireless sensor networks (WSNs), dissipates a non-negligible portion of the energy budget of a sensor node. Broadcasting is achieved by the dissemination of broadcast packets (originated at the BS) by a set of relay nodes, which constitute a backbone so that all sensor nodes receive broadcast packets. Utilization of multiple backbones is necessary to achieve balanced energy dissipation of sensor nodes in broadcasting. In this study, we propose two mixed integer programming (MIP) models (i.e., the flow-based model and the node-based model), which minimize the energy dissipation of the highest energy-consuming node for broadcasting by utilizing multiple backbones. Balanced energy minimization and delay minimization objectives are integrated through a goal programming (GP) framework built upon the foundation provided by the scalable node-based model. Performance evaluations based on the optimal solutions of our models reveal that maximum energy dissipation and delay in WSN broadcasting can be significantly reduced, simultaneously, by utilizing multiple backbones (e.g., with two backbones maximum energy dissipation and delay can be, concurrently, reduced by more than 2% and 22%, respectively, in comparison to the single backbone case, likewise, it is also possible to simultaneously reduce maximum energy dissipation and delay more than 8% and 13%, respectively, depending on the priorities assigned to the objectives). Nevertheless, employing more than two backbones does not provide any significant performance improvements. © 2023 Elsevier B.V., Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK, Busra Gultekin was supported by TÜBİTAK BİDEB 2210 Scholarship Programme, Turkey .

An experimental study is performed to characterize the pressure drop and the power consumption in Oscillatory Baffled Reactors, using dimensionless numbers: the oscillatory Fanning friction factor (f osc ) and the Power number (Po), respectively. Two baffle geometries (one-orifice and three orifices) are tested, for different fluids and oscillating amplitudes. The range of oscillatory Reynolds numbers (Reosc ) tested is 10–1000. Data reduction based on the statistical fitting and the FFT of the pressure drop and velocity signals is introduced to assess the maximum pressure drop and the phase lag between both signals. The new set of experimental data proves the limitations of the conventional models available in the open literature. f osc and Po provide consistent dimensionless results for the different working fluids tested and their trends are clearly related to different flow behaviours: laminar or chaotic flow. Correlations for f osc and Po as a function of Reosc and dimensionless amplitude are obtained.

This work presents a novel sequential sampling approach to the multi-objective reliability-based design optimization of moment-resisting steel frames subjected to earthquake excitation. The optimization problem is formulated with two objective functions, namely, the total mass and the energy dissipated by beam members of the frame, and subject to uncorrelated probabilistic constraints on dynamic responses under the effects of correlated random parameters of floor masses, external loads, and material properties. The dynamic responses for a small number of designs are found by nonlinear response history analysis and further approximated by Gaussian process (GP) models to mitigate the computational burden during the optimization process. Approximate solutions sorted among existing candidate solutions are updated after each optimization iteration using discrete random local and global searches. The GP models are also refined after each optimization iteration by specifying new sampling points that lie on the Pareto front of a bi-objective deterministic maximization problem formulated for the improvement in the current approximate solutions and the feasibility of the new sampling points. As demonstrated in a test problem, the new sampling points tend to distribute in the neighborhood of the exact solutions, thereby underpinning a quick termination as well as the robustness of the proposed method. Optimization results from the test problem and a design example show that good approximate solutions are always obtained as the solution quality converges.

Abstract: Hydraulic jumps are commonly employed as energy dissipators to guarantee long-term operation of hydraulic structures. A comprehensive and in-depth understanding of their main features is therefore fundamental. In this context, the current study focused on hydraulic jumps with low Froude numbers, i.e. Fr1 = 2.1 and 2.4, at relatively high Reynolds number: Re ~2 × 105. Experimental tests employed a combination of dual-tip phase-detection probes and ultra-high-speed video camera to provide a comprehensive characterisation of the main air-water flow properties of the hydraulic jump, including surface flow features, void fraction, bubble count rate and interfacial velocities. The current research also focused on the transverse distributions of air-water flow properties, i.e. across the channel width, with the results revealing lower values of void fraction and bubble count rate next to the sidewalls compared to the channel centreline data. Such a spatial variability in the transverse direction questions whether data near the side walls may be truly representative of the behaviour in the bulk of the flow, raising the issue of sidewall effects in image-based techniques. Overall, these findings provide new information to both researchers and practitioners for a better understanding of the physical processes inside the hydraulic jump with low Froude numbers, leading to an optimised design of hydraulic structures. Article Highlights: Experimental investigation of air-water flow properties in hydraulic jumps with low Froude numbersDetailed description of the main air-water surface features on the breaking rollerTransversal distribution of the air-water flow properties across the channel width and comparison between centreline and sidewall., Hydraulic Structures and Flood Risk

Existing masonry buildings are very frequently part of the architectural context for several countries all over the world. These constructions often feature masonry walls as vertical structural elements, and timber floors and roofs as horizontal components. The often poor characteristics of masonry, along with the in-plane flexibility of the floors and their frequently weak connections to the walls, make such buildings very vulnerable against seismic actions, as proved by the destructive consequences of several earthquakes in the last decades. The improvement of seismic capacity of existing masonry buildings is still an open research topic, with several retrofitting techniques for masonry walls and timber floors being proposed and tested. An acknowledged way of increasing the structural performance of a masonry building under an earthquake consists of the development of the so-called box behaviour, enabling the construction to react as a whole to the ground motion. To pursue the box behaviour, the main adopted retrofitting methods are linked to in-plane stiffening of the timber floors, and seismic strengthening of the connections. In this context, several (nonlinear) analysis method for masonry buildings (e.g. the pushover analysis) assume that rigid floors are present, and out-of-plane failure mechanisms of masonry are prevented. Therefore, also in the context of numerical modelling, the in-plane response of the diaphragms is generally not taken into account in detail, since they are only considered as linear elastic orthotropic membranes or stiff elements. However, past seismic events demonstrated that an excessive stiffening of the diaphragms can also be detrimental. This triggered the study of several lighter, moderately stiff strengthening methods for timber floors, referred to various architectural frameworks. Since existing floors proved to be excessively flexible, but also too stiff diaphragms could not be recommendable, the overarching research, Bio-based Structures & Materials

An energy equation for fatigue crack growth in adhesive joints is proposed. Fatigue experiment on DCB adhesive joint specimens was used to derive the relation between fatigue crack growth rate (da/dN) and energy variables in this equation. The result shows plastic dissipation and change in stored strain energy, whose relation with da/dN both depending on the stress ratio, are not straightforwardly related to da/dN. The energy dissipated in new crack surface formation is the variable that straightforwardly related to da/dN within the range of test, and its relation with da/dN is one-to-one, regardless of the influence of stress ratio., Structural Integrity & Composites

An energy equation for fatigue crack growth was proposed. It equates the total external work per cycle (dW/dN) to the sum of plastic dissipation (dUpl/dN), change in strain energy stored (dUe/dN) and the energy dissipated in new crack surface formation (dUa/dN). Fatigue crack growth experiment of 7075-T6 was used to derive the relation between fatigue crack growth rate (da/dN) and variables in this equation. The result shows dUpl/dN and dUe/dN are not straightforwardly related to da/dN. The dUa/dN, whose value cannot be obtained sufficiently precise experimentally, can be the variable straightforwardly related to da/dN within the range of test., Structural Integrity & Composites

Auxetic materials, possessing negative Poisson’s ratios (NPRs), have the ability to shrink (or expand) in the lateral direction under an axial compressive (or tensile) force respectively. Due to this unique feature, an auxetic material is found to sustain high energy absorption capacity, fracture toughness and shear resistance and thus regarded as one of the future materials in the field of impact protection. However, civil engineering applications of auxetic structures or materials are minimal due to miscellaneous restrictions on NPR effects. Accumulative developments in auxetics have facilitated their applications in cementitious materials in recent years. This paper presents an overview of recent advances in the development of auxetic cementitious composites and analyses and summarises their mechanical properties under different loading conditions. Prior to extensive finite element simulations, more attention has been given to the limited experimental results. Particular attention is paid to the expansionary feasibility of the parent material to introduce auxetic behaviour, with precise identification of the limitations, innovative composition methods and facilitation of auxetic features. Finally, the paper outlines the limitations of the current research and envisages few future research opportunities in auxetic cementitious composites.

The unimolecular dissociation and infrared radiative cooling rates of cationic 1-hydroxypyrene (OHPyr+, C16H10O+) and 1-bromopyrene (BrPyr+, C16H9Br+) are measured using a cryogenic electrostatic ion beam storage ring. A novel numerical approach is developed to analyze the time dependence of the dissociation rate and to determine the absolute scaling of the radiative cooling rate coefficient. The model results show that radiative cooling competes with dissociation below the critical total vibrational energies Ec = 5.39(1) eV for OHPyr+ and 5.90(1) eV for BrPyr+. These critical energies and implications for radiative cooling dynamics are important for astrochemical models concerned with energy dissipation and molecular lifecycles. The methods presented extend the utility of storage ring experiments on astrophysically relevant ions.

Tin diselenide (SnSe2) is a layered semiconductor with broad application capabilities in the fields of energy storage, photocatalysis, and photodetection. Here, we correlate the physicochemical properties of this van der Waals semiconductor to sensing applications for detecting chemical species (chemosensors) and millimeter waves (terahertz photodetectors) by combining experiments of high-resolution electron energy loss spectroscopy and X-ray photoelectron spectroscopy with density functional theory. The response of the pristine, defective, and oxidized SnSe2 surface towards H2, H2O, H2S, NH3, and NO2 analytes was investigated. Furthermore, the effects of the thickness were assessed for monolayer, bilayer, and bulk samples of SnSe2. The formation of a subnanometric SnO2 skin over the SnSe2 surface (self-assembled SnO2/SnSe2 heterostructure) corresponds to a strong adsorption of all analytes. The formation of non-covalent bonds between SnO2 and analytes corresponds to an increase of the magnitude of the transferred charge. The theoretical model nicely fits experimental data on gas response to analytes, validating the SnO2/SnSe2 heterostructure as a suitable playground for sensing of noxious gases, with sensitivities of 0.43, 2.13, 0.11, 1.06 [ppm]−1 for H2, H2S, NH3, and NO2, respectively. The corresponding limit of detection is 5 ppm, 10 ppb, 250 ppb, and 400 ppb for H2, H2S, NH3, and NO2, respectively. Furthermore, SnSe2-based sensors are also suitable for fast large-area imaging applications at room temperature for millimeter waves in the THz range. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

DATA DESCRIPTION Title alternative Raw data of experimental results of the temporal variation in the wave height at measurement sections in straight and meandering channels - dambreak_straightchannel.xlsx - dambreak_meanderingchannel.xlsx In these Excel data, the name of the sheet "High" means High Froude number condition. Description This dataset contains raw data Raw data is indicated by below - Time (second) - meassurement section 1 (s=3.572m) - meassurement section 3 (s=5.522m) - meassurement section 4 (s=6.530m) - meassurement section 5 (s=7.602m) - meassurement section 7 (s=9.552m) - meassurement section 8 (s=10.56m)

One of the noteworthy developments for the next generation of Eurocode 8 is the inclusion of a complete displacement-based design approach using nonlinear static or dynamic analyses and a set of verifications at the global or local levels, depending on the structural typology. This work investigates the consistency between such approach and classical force-based design applying behaviour factors, for reinforced concrete moment resisting frames. A set of structures designed according to the rules of the three novel ductility classes are used as case studies. Nonlinear static analyses are performed according to a new bilinearisation procedure, and target displacements are computed for the limit states of damage limitation, significant damage, and near collapse. The resulting structural demand, determined globally and in terms of the maximum local deformations among the members, is compared with the recommended values for global and local displacement capacities. Two alternative methods are then used to compute the components of the behaviour factor, which are critically confronted with the currently suggested upper-bound values for design. Finally, a procedure to harmonise displacement-based and force-based approaches is outlined, aiming at deriving values for the design behaviour factor that depend not just on the ductility class but also on additional design parameters which this investigation shows to influence the response.

Elastomeric materials are extensively used in energy dissipation applications to mitigate large lateral displacements and attenuate vibrations. One way of exploiting the capabilities of elastomeric materials is using shear-damping mechanisms such as viscoelastic damping devices (VEDs). In this research the freedom of design offered by additive manufacturing technology is utilized to produce 3D printed elastomeric parts that act as the viscoelastic layer in an energy damping device. A mechanically interlocked viscoelastic damper (MIVED) with a jigsaw-like interlocking mechanism was designed and manufactured. MIVED is composed of a rigid and soft phase. It operates in two modes, modes I and II, that depend on the stiffnesses of the rigid and soft phases as well as the stiffness of the connection used to fix it to the testing machine or structural element. The modes are illustrated through changing the rigid and soft phase materials. For that purpose, two devices were fabricated MIVED-1 and MIVED-2 to observe modes I and II, respectively. The rigid phase of MIVED-1 was made of steel, while the soft phase is 3D printed using vi thermoplastic polyurethane (TPU). MIVED-2 had a rigid phase made from 3D printed fiber reinforced nylon, and 3D printed TPU injected with silicone rubber for the soft phase. The devices were cyclically tested under different amplitudes and frequencies, and the response was examined. 3D printed TPU was mechanically characterized using uniaxial cyclic tension tests under different rates and different printing processing parameters. Stress relaxation tests were also conducted to obtain the viscoelastic behavior of the TPU material. Material characterization of TPU was used to develop a finite element (FE) model that is used to simulate the mechanically interlocked damper. The FE model was validated with the experimental observations of TPU specimens and MIVED-1 and was then used to examine the significance of damper geometry and mat