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Abstract The traditional tunnel drilling and blasting method places cut holes at the lower center of the excavation face, resulting in an excessive number of blasting holes. With the continuous increase in cross-section area, this design concept can no longer meet the requirements of safe and efficient tunnel boring for large cross-section tunnels. This paper puts forward the theory and method of reduced-hole blasting for large cross-section tunnels, as an alternative to the traditional drilling and blasting method of the “more holes, less charge” design concept. Based on the explosion energy dissipation law and rock’s critical crushing energy dissipation characteristics, the calculation method of the extrapolation distance of the wedge-cut holes is given. The optimum extrapolation distance of the wedge-cut holes was verified using numerical simulation and field tests. The results show that the number of drilling holes can be reduced by about 15.8% using the theory and method proposed in this paper, and at the same time, the damage of retained rock can be effectively controlled. The results of this study can provide a reference for the design of blast network parameters for similar large cross-section tunnels.

Currently, although energy conservation related research in buildings is a matter of great urgency in the context of an ever more serious energy crisis, people seem to pay more attention on the field of civil engineering, such as the design, construction, monitoring and maintenance management of building structures. This is also evidenced by the authors' extensive research and strong practical engineering experience in infrastructure projects such as bridges. This study first presents the general building energy situation. The state of the art of the energy in buildings is then reviewed, followed by pointing out the intelligent monitoring-based future direction, and then the final goal towards the smart city can be expected. Specifically, more than one hundred published papers are selected for sample analysis, taking into account different research topics and different publication dates etc. The research topics, research methods and research conclusions of these published papers are very different, and they have not yet produced results that could be generally accepted. Actually, most of the published papers focus on the analysis and conservation of building energy, including the energy model for analysis and prediction, the energy affected by resident behavior and building forms, the renewable energy utilization and zero energy building. While a small part of the published papers is concerned with the resilient structural energy dissipation and collapse-resistant. Furthermore, the intelligent monitoring of building energy, supported by advanced sensor development and big data analysis technology, is also providing us a more promising future on the way to the smart city. It should be further noted that the design and construction codes or standards related to building energy have not yet been retrieved, and these have a strong guiding significance for engineering practice. Therefore, more research needs to be done to expect a better practical outcome.

The use of seismic isolators is a design method that involves inserting a flexible element at the base of the structure to decouple its movement from that of the ground to reduce vulnerability to earthquakes. They also make it possible to reduce the demand for force and deformation on the various structural elements. The aim of this research is to evaluate the contribution of HDRB high damping elastomeric seismic isolators in the reduction of seismic forces. It also consists in comparing the results of the dynamic analysis of the two fixed base structures in frames or frames braced by shear walls with the isolated structure mounted on an HDRB elastomer system and subjected to the same seismic excitation using the SAP 2000 calculation software. The results obtained showed an attenuation in the accelerations, a lengthening of the period, strong reduction in displacements and a reduction in the shearing force at the base of the isolated structure compared to fixed base structures.

This paper proposes a novel energy dissipation low reinforced concrete (RC) shear wall to improve the seismic performance of the high-rise building. The novel energy dissipation low RC shear wall composes of shear wall, inner several vertical gaps and some built-in new lead dampers. In the novel shear wall, the inner lead dampers can produce a marked effect on energy dissipation and shear transmission. This paper first presents the simulation studies of lead dampers, including the simulation method and the simulation analysis. Based on the above study results, the following contents use ABAQUS software to study the seismic performances of the new energy dissipation shear wall, including the damage patterns, hysteresis curves, stiffness degradation and energy dissipation capacity. The analysis results show the proposed shear wall has well seismic performance. Meanwhile, the ductility of the proposed shear wall is higher than that of the conventional low shear wall. The bearing capacity is higher than that of the shear wall with vertical gaps. But the energy dissipation capacity decreases with the increase of the axial pressure ratio under a large axial pressure ratio. Especially, the number and the arrangement of lead dampers have an obvious effect on the seismic performance.

Quantum-dot cellular automata (QCA) is a promising nanotechnology that appears to meet the requirements of high speed radar applications. Due to its advantages, including its extremely low power dissipation and less occupied area, it is highly regarded. The multiplier module is an essential component in Phased Array Radar (PAR). In the real-time PAR based systems, many applications like digital beam forming, local oscillators, and communication receivers etc. requires multiplication operation. However, the most important factors in these systems are the area and power consumption. This paper presents an ultra-low power vedic multiplier using QCA technology, and it provides the effective clocking, reduce the number of cells, and low energy dissipation. The 4×4 vedic multiplier utilizes only 2940 cells and occupies 7.33μm2 area with 7.64×10−1eV of energy dissipation. The total consumed power of this module is 1.61nW. This architecture outperforms complementary metal-oxide-semiconductor (CMOS) based circuits in terms of power by 90%. The proposed contribution will initiate a new direction of research into real-time PAR based systems.

Shear wall structures are widely used in high-rise buildings, due to their satisfactory integrity and force transmission, thus superior seismic performance. However, due to insufficient material strength, non-standard construction, and the fact that some buildings have reached their design service life, many shear wall structures can no longer resist natural disasters such as earthquakes, nor can they meet the functional requirements. Therefore, it is of practical significance to reinforce shear wall structures and study their seismic performance. This paper uses the partial replacement method to reinforce and renovate concrete shear walls, using modified reactive powder concrete (MRPC) with excellent durability and toughness as the replacement material. The effects of different materials and different replacement positions on the seismic performance of shear walls were studied. A total of 5 shear wall specimens were designed and manufactured, including Specimen SW1 that did not reach the designed concrete strength, Specimen SW2 that met the original design strength, SW3 with the middle part of the wall was replaced by MRPC, and another two specimens that used ordinary concrete (SW4) or MRPC (SW5) to replace the two ends of the wall. Pseudo-static tests were carried out on the specimens and their seismic performance indicators such as bearing capacity, stiffness degradation, displacement ductility, and energy dissipation capacity were analyzed. Finally, finite element simulation analysis was also performed for the specimens. The results show that compared with the original design strength specimen SW2, the specimens SW4 and SW5, which used C45 concrete and MRPC to replace the two ends of the walls, effectively improved the bearing capacity, energy dissipation, and ductility of the shear wall. By comparing the mechanical properties of SW3 and SW5, it can be found that replacing the two ends of the shear wall can obtain better results.

This paper aims at investigating the triaxial behavior of Autoclaved Aerated Concrete (AAC) under extremely high pressures, and experimentally determine Equation of State (EOS) for several different AAC densities. Oedometric tests were carried out using a home-made high-pressure triaxial apparatus, and pressures up to ~500 MPa were applied. The complete pressure-bulk strain relationships were measured, and new findings and insights were obtained. The paper presents the testing set-up and the measurement system. The data processing method accounting for the AAC pronounced shortening during the ongoing test is described using a weighted functions procedure for the circumferential strains’ calculation, with which the confining pressure was determined. The boundary conditions effects on the test results were investigated, and a new technique for specimen insulation was suggested to ensure loading without friction and the prevention of local shear failure. The experimental EOS for different AAC densities were obtained. EOS curves for different specimens with the same density demonstrated good to very good repeatability of the EOS curves over the entire pressure range. Based on the tests results and the density’s span, three classes of AAC are proposed. A preliminary attempt to apply the newly obtained EOS curves has been carried out to examine the energy dissipation for three different dynamic load levels. Although this is a preliminary stage that is beyond the objective of this paper, early interesting results were observed where an optimal AAC density, for which the highest energy has been absorbed, was identified. This finding encourages inclusion of that preliminary study as a closure section. Numerical simulations of wave propagation through ACC layers of different densities, laid on rigid supporting slabs, was carried out. The minimum total impulse imparted to the rigid slab was found for the optimal AAC density that has been determined above.

Energy efficiency considerations in terms of reduced power dissipation are a significant issue in the design of digital circuits for very large-scale integration (VLSI) systems. Quantum-dot cellular automata (QCA) is an emerging ultralow power dissipation approach, distinct from traditional, complementary metal-oxide semiconductor (CMOS) technology, for building digital computing circuits. Developing fully reversible QCA circuits has the potential to significantly reduce energy dissipation. Multiplexers are fundamental elements in the construction of useful digital circuits. In this paper, a novel, multilayer, fully reversible QCA 8:1 multiplexer circuit with ultralow energy dissipation is introduced. The power dissipation of the proposed multiplexer is simulated using the QCADesigner-E version 2.2 tool, describing the microscopic physical mechanisms underlying the QCA operation. The results show that the proposed reversible QCA 8:1 multiplexer consumes 89% less energy than the most energy-efficient 8:1 multiplexer circuit previously presented in the literature.

The internal flow scale of a Pelton turbine is variable, and the interaction between the jet and the bucket has strong transient characteristics, resulting in an incomplete understanding of its internal vortex structure evolution and energy dissipation mechanisms. In order to reveal the influence of vortices on the flow regime and energy dissipation mechanisms in the turbine, this paper establishes the correlation between the unsteady flow characteristics and energy dissipation inside the Pelton turbine based on the energy balance equation and quantifies the energy losses inside the turbine. The results indicate that vortex structures present a non-uniform distribution inside the jet, which disrupts the uniformity of the jet velocity distribution, resulting in an uneven distribution of high-vorticity zones on the bucket surfaces and intensifying flow interference among the buckets. The strong shear flow caused by the downstream flow detachment of the needle guide, the turbulent boundary layer on the jet surface, and the wake effect downstream of the needle tip are the main reasons for the dissipation of fluid kinetic energy. The distribution range of energy loss on the rotating bucket closely corresponds to the position of the high-vorticity zone. Energy dissipation inside the turbine is primarily in the form of turbulent kinetic energy, and the injectors and runner are the primary energy dissipation components. Moreover, inside the injectors, each form of energy loss remains relatively constant, whereas inside the runner, its rotation induces fluctuating energy losses attributed to Reynolds stress work. The results contribute to an enhanced understanding of the energy dissipation characteristics and complex flow mechanisms within the turbine, providing reference for the optimisation and efficient operation of the multi-nozzle Pelton turbine.

This paper is concerned with the modeling of power dissipation due to friction and its relation with wear estimation in wheel–rail contact. Wear is a complex multi-scale and multi-physical phenomenon appearing in rolling contact. Wear is generated by high contact stress and the work of friction forces. This phenomenon leads to the appearing of the worn material in the form of wear debris between contacting surfaces. In contact models, wear is usually described in terms of the wear depth function. This function modifies the gap between the contacting bodies as well as the shape of the surfaces of the wheel and rail in contact. In this paper, besides the wear depth function, the dissipated energy, rather than the contact stress, is taken into account to evaluate the wear impact on rail or wheel surfaces. The dissipated energy allows us to more precisely evaluate the wear debris amount as well as the depth of wear and its distribution along the contact interface. A two-dimensional rolling contact problem with frictional heat flow is considered. The elasto-plastic deformation of the rail is considered. This contact problem is governed by a coupled system of mechanical and thermal equations in terms of generalized stresses, displacement and temperature. The finite element method is used to discretize this problem. A discretized system of equations with nonpenetration and friction conditions is transformed and formulated as a nonlinear complementarity problem. The generalized Newton method is applied to numerically solve this mechanical subproblem. The Cholesky method is used to find the solution of the heat-conductive problem. The dissipated power is evaluated based on the resultant force and slip at a reference point. Numerical results including the distribution of slip velocity, power factor and wear rate are provided and discussed.

The bolted joints exhibit typical nonlinear hysteresis under tangential loading, and the deviations of the preload in the bolt group add to the complexity of the model describing this behavior. In this paper, based on the mechanical analysis of the bolt group, a new methodology for predicting hysteresis behavior under non-uniform preload was proposed. Firstly, based on the moment equilibrium within the framework of material mechanics and the tangential stiffness model of the joint interface, a new coordination equation of displacement and force between the bolted joints was deduced, which could realize the calculation of the bolt group loading curve. Then, the PCOM (Preload Co-Occurrence Matrix) was constructed considering the arrangement of the joints, and the indices related to the spatial distribution of the preload were extracted from PCOM. The results of GCA (Grey Correlation Analysis) showed that the indices of PCOM were closely related to the hysteresis behavior of the bolt group. Finally, the prediction of energy dissipation could be realized by using the indices extracted from PCOM and the SVM(Support Vector Machine) regression model. The prediction results were in good agreement with the simulation and experiment, which verified the validity of the methodology proposed in this paper.

ABSTRACTIn the present time, the Ministry of Water Resources and Irrigation starts to construct new barrages across the Nile River and the main canals to replace the oldest ones, which are not able to withstand the requirements of increasing head difference between the upstream and downstream water levels upon the gates. This paper is focused on investigating experimentally the flow characteristics downstream the vertical sluice gates of Bahr Yousef regulator in case of flow over gate and flow under gate and the proper design for stilling basin with high efficiency in dissipation of water energy downstream the vertical gate with low cost. In the present study experimental work was carried out on a 2-D flume with 1.0 m wide, 26.0 m long, and 1.2 m deep, with discharges range from 22 to 395 l/s at the Hydraulics Research Institute laboratory. This experiment is physically based with scale 1:8.5. The experimental tests involved the observations and measurements of hydraulic phenomena in one single bay of the regulator in case of flow under/over gate. In these tests, there was a group of variables such as; the gate opening, flow rate, pressure head, upstream and downstream water levels, number of gates opening, and D50 of riprap protection. The influence of these parameters on downstream flow characteristics and the rip-rap size was investigated downstream the stilling basin. Comparative analysis between flow under the gate and flow over the gate was carried out. The results showed that the case of flow under gate gave more normal velocity distribution with low turbulent and high efficiency in dissipation of water energy downstream the vertical gates, and it was recommended for the operation of the regulator. Also, the obtained results showed that the size of riprap protection with D50 equal 0.2 m are stable, economic, and reduced the stilling basin length.

Utilizing a two-stage vertical pump as turbine (TVPAT) is an economically method for constructing small-scale pumping and storage hydropower stations at high head-low discharge sites, such as underground coal mines. The energy dissipation mechanisms in flow passages are theoretically important for performance prediction and geometric parameter optimization. In this paper, the energy dissipation within the TVPAT has been studied using entropy generation theory, which can be applied to visual, locate and quantify energy dissipation. The numerical solution of entropy dissipation components was extracted on turbine modes in different flow rates using the steady-state single-phase SST k-ω turbulence model. The numerical results show that the energy dissipation in TVPAT mainly comes from turbulent fluctuation (43.6%-72.1%) and blade surface friction (27.8%-58.2%). The runners are the main source of turbulent entropy (SD′ ) generation (47.2%-83.3%). The contribution of the return channel and spiral case to the generation under overload conditions is significant, accounting for 33.6% and 14.3 at 1.3QBEP, respectively. Flow field analysis reveals that high generation within a runner are located in the striking flow region of the leading edge, the flow squeezing region in the blade channel, and the wake region of tailing edge. The mismatch between the placement angle of the blades or guide vanes and the liquid flow angle is an important incentive for SD′ generation. Moreover, hydraulic energy is consumed through the interaction between mainstream and local inferior flows such as separation and vortices, as well as the striking and friction between local fluid and wall surfaces.

In this paper, we are concerned with the process of experimental information gain. Building on previous work, we show that this is a discontinuous process in which the initiating quantum-mechanical matter–instrument interactions are being turned into macroscopically observable events (EOs). In the course of time, such EOs evolve into spatio-temporal patterns of EOs, which allow conceivable alternatives of physical explanation to be distinguished. Focusing on the specific case of photon detection, we show that during their lifetimes, EOs proceed through the four phases of initiation, detection, erasure and reset. Once generated, the observational value of EOs can be measured in units of the Planck quantum of physical action h=4.136×10−15eVs. Once terminated, each unit of entropy of size kB=8.617×10−5eV/K, which had been created in the instrument during the observational phase, needs to be removed from the instrument to ready it for a new round of photon detection. This withdrawal of entropy takes place at an energetic cost of at least two units of the Landauer minimum energy bound of ELa=ln⁡2kBTD for each unit of entropy of size kB.

Numerous problems have emerged with the development of HVDC transmission technology. One of them is the fault current that occurs when there is an issue in the line. In particular, in the case of a PTP (pole-to-pole) fault, a DCCB design suitable for the direction is required because the fault current flows through the positive and negative poles. In the case of PTP fault, a fault current of the same value occurs in the opposite direction, and in the case of DCCB, the breaking efficiency may be reduced or even impossible to break due to a mistake in the emission direction or a wrong design. In particular, when designing using several unidirectional DCCBs, it is cheaper and consumes less area than typical DCCBs, so it is economical, but this problem may be more prominent. To solve this problem, this paper proposes a 4- pole Hybrid HVDC circuit breaker to solve this problem. This circuit optimizes the DCCB internal components through quantitative analysis of the fault current to reduce the influence of the residual fault current as well as the previously most important parameter, Zero-Cross Time (ZCT). We also verified the circuit’s energy dissipation process to increase reliability. The circuit in this paper is simulated based on the VSC-based HVDC transmission link. Physically analyze the derived results and described the circuit mechanism.

Stepped spillways have become increasingly popular due to their stability and ability to dissipate energy effectively. While previous studies have evaluated various aspects of stepped spillways, this paper specifically investigates the impact of step height on energy dissipation and flow characteristics. The study aims to analyze the flow and energy dissipation rates of stepped spillways with different step heights, providing valuable insights into the design and construction of such structures. To achieve this, a series of laboratory experiments were conducted using stepped spillway models of varying step heights. The models were subjected to various flow rates within a horizontal flume of 0.3 m width, with a non-dimensional discharge (yc/h) range of 0.14 to 3.5. The outcomes indicated that the model with a larger step height exhibited greater energy dissipation, up to approximately 28%, compared to the model with a smaller step height.

In this paper, the dissipative energy in the damage process was employed to solve the damage variable while the damage constitutive model was established. In this model, the Mohr-Coulomb criterion and the energy dissipation theory were introduced. Considering the hardening and softening characteristics of rock during loading, the non-associated plastic flow rule was applied to describe the plastic deformation of rock, and the damage variable was calculated by quoting the dissipation energy and damage energy dissipation rate in the damage process. Based on the conventional triaxial loading-unloading experiments, the energy consumption and damage evolution law of rock was analyzed. The expression of damage energy dissipation rate was established, and the parameters in the model were calibrated. Simulation was conducted by this model and the simulation results were compared with the experimental results to validate the model. In this process, the following conclusions were obtained: (1) in the elastic stage, the damage dissipation energy increases slowly with the axial strain, showing an upward concave curve, and the growth rate reaches the maximum near the peak-stress. In the residual stage, the relationship between damage dissipation energy and axial strain is linear; (2) based on elastic modulus associated damage definition, the experimental results show that there is a damage variable limit less than 1, and the damage variable limit gradually decreases with the increase of confining pressure; (3) the model in this paper can be used to investigate the strength, hardening, softening characteristics and strain law of rock under different confining pressures during the loading process. The numerical simulation results can describe the stress-strain relationship and damage evolution law of rock.

This paper proposes a new toggle-style negative stiffness viscous damper (TNVD), and evaluates the performance of the TNVD with the displacement amplification factor (fd) and the energy dissipation factor (fE). Firstly, the composition and characteristics of the TNVD are introduced. Subsequently, the displacement amplification factor is introduced to evaluate the displacement amplification ability of the TNVD, and it is decomposed into a geometric amplification factor and an effective displacement coefficient. Then, based on the geometric amplification factor and effective displacement coefficient, the correlation between the TNVD’s displacement amplification ability and inter-story deformation is studied, and an improved TNVD is proposed. By the comparison of the finite element calculation results, it is found that the improved TNVD can utilize the assumption of small structural deformation. After that, the impacts of plentiful aspects, such as the length of the lower connecting rod, the horizontal inclination angle of the lower connecting rod, the inter-story deformation limit, the cross-sectional area of the connecting rod, the damping coefficient, and the negative stiffness on the fd and fE of the improved TNVD, are expounded. The research results show that when the length of the TNVD’s lower connecting rod remains unchanged, the fd and fE present a trend of increasing first and then decreasing with the increase in the horizontal inclination angle of the lower connecting rod. When the inter-story deformation is fixed, there exists an optimal lower connecting rod’s length that satisfies a specific relationship to achieve the optimal geometric amplification factor of the TNVD. By adjusting the damping parameters of the TNVD, we can obtain a better effective displacement coefficient greater than 0.95 in the proposed target region. Meanwhile, the fd and fE increase with the decrease in the negative stiffness. An optimization strategy for the improved TNVD has been proposed to ensure that the TNVD has the characteristics of operational safety, ideal displacement amplification capability, and energy dissipation capability. Furthermore, a multi-objective control design method with an additional improved TNVD structure is proposed. The vibration reduction effect of the structure with the improved TNVD and the effectiveness of the optimization strategy are verified through examples.

Fatigue limit assessment methodologies based on the thermography technique are comprehensively studied in this work. Three fundamental indicators pertaining to temperature increase, intrinsic energy dissipation, and thermodynamic entropy are discussed in sequence. The main train of thought of thermo-based research is outlined. The main objective of this paper is, on the one hand, to describe some works that have been accomplished in this field and, on the other hand, to present further potential for future studies involving fatigue behaviors and thermography approaches.

The backfill area of tunnel projects may deform or collapse due to the cyclic disturbance of groundwater and train loads. Hence, the anti-deformation and crack resistance performance of backfill materials under cyclic disturbance is critical to engineering safety. In this paper, concrete was produced by mixing 0.85 mm, 1–3 mm and 3–6 mm rubber particles instead of 10% sand, and tested to discuss the effect of rubber particle size on the deterioration of concrete material properties (compressive characteristics and energy dissipation) after bearing cyclic loading. The stress–strain curve and various parameters obtained through the uniaxial compression test and cyclic load test were used to explore the optimal grain size that can be applied to the tunnel engineering backfill area, and numerical simulation was adopted to calculate the deformation of the surrounding rock and the structural stress of different backfill materials. Research shows that the increase in particle size lessens the compressive strength, deformation resistance and cracking resistance of specimens, but after the cyclic loading test, the concrete material deterioration analysis indicates that rubber concrete has lesser and more stable losses compared to ordinary concrete, so the optimum rubber particle size is 0.85 mm. Numerical calculations show that RC-1 reduces the arch top displacement by 0.4 mm, increases the arch bottom displacement by 0.6 mm and increases the maximum principal stress by 11.5% compared to OC. Therefore, rubber concrete can ensure the strength and stability requirements of tunnel structures, which can provide a reference for similar projects.

The large amount of secondary effects in complementary metal-oxide-semiconductor technology limits its application in the ultra-nanoscale region. Circuit designers explore a new technology for the ultra-nanoscale region, which is the quantum-dot cellular automata (QCA). Low-energy dissipation, high speed, and area efficiency are the key features of the QCA technology. This research proposes a novel, low-complexity, QCA-based one-bit digital comparator circuit for the ultra-nanoscale region. The performance of the proposed comparator circuit is presented in detail in this paper and compared with that of existing designs. The proposed QCA structure for the comparator circuit only consists of 19 QCA cells with two clock phases. QCA Designer-E and QCA Pro tools are applied to estimate the total energy dissipation. The proposed comparator saves 24.00% QCA cells, 25.00% cell area, 37.50% layout cost, and 78.11% energy dissipation compared with the best reported similar design.

Steel box girders are widely used in cable-stayed bridges, while they are prone to severe damage under explosions. This paper investigates the deformation and energy dissipation of steel box girder of cable-stayed bridges under blast impact, caused by the accidental explosions of tanker trucks and vehicles. In this study, Hypermesh and LS-DYNA are employed to simulate the dynamic responses of a real steel box girder cable-stayed bridge under explosions. The deformation response and energy absorption of the box girder under explosions are investigated. Several failure modes and failure processes are analyzed and summarized. The findings indicate that the failure mode of an orthotropic steel bridge panel under blast impact is primarily local damage, with the damage process being divided into three stages: local plate deformation, fragment formation, and petal formation. For bridge deck explosions, the main energy dissipation components of steel girders are the bridge panel, web, diaphragm and rib stiffeners. The research results can provide the basis for the follow-up study on the anti-explosion safety of bridge structures.

The reservoir is an important component of hydraulic projects for supplying water to the city. For guaranteeing reservoir safe operation, stepped spillways are often used to discharge the flood from the reservoir. But under large unit discharges, cavitation erosion and low energy dissipation may occur on stepped spillways, which possibly leads to the hydraulic structures being instable and the reservoir outwork for water supply. Herein, an orifice plate is introduced as a pre-aeration device for the stepped spillways to avoid cavitation damage. To detail the effect of orifice plate on the flow over the stepped spillways, experiments were conducted. The results demonstrate that the orifice plate contracted the flow into a jet. Large amounts of air were entrained, and cavitation damage could be avoided according to the air concentration distributions along the stepped spillways. The orifice plate also significantly increased the energy dissipation of stepped spillways. Further, flow depth before the orifice plate increased because of flow block, and was emphatically discussed for providing a calculation formula to estimate the jet trajectory. HIGHLIGHTS The orifice plate generates a jet to entrain air, which can avoid cavitation damage for stepped spillways with large unit discharges.; The orifice plate increases the energy dissipation of the stepped spillway.; The relationship of take-off flow depth and hydraulic as well as structure parameters of the orifice plate are revealed.; This paper presents the formula of jet trajectory based on the corrected take-off flow depth.;

Important water structures known as stepped spillways are used to dissipate energy, aerate rivers, and reduce the cost of the downstream pool. The aim of this study is to increase the energy dissipation rate by proposing an alternative design to the flat stepped spillways, which are frequently used in practice. For that reason, the Circular Stepped Spillway (CSS) has been constructed and numerically investigated in this paper. The energy dissipation rate of the CSS and the flat stepped spillway has been compared using three different models and discharges. According to the simulation findings, the CSS performs better as the step radius gets smaller. The CSS models with step depths of 0.50, 1.50, and 2.50 cm have dissipated up to 21.4, 38, and 50.7% more energy than the flat stepped spillway, respectively. HIGHLIGHTS Circular stepped spillway (CSS) is more efficient than the flat stepped spillway for energy dissipation.; As the radius of the step on the CSS decreases, the energy dissipation rate increases.; As the step depth of the CSS increases, the energy dissipation rate increases.; The flow depth of the CSS is higher than the flat stepped spillway due to the amount of air entering the flow.;

Jurassic red sandstone is widely distributed in the Three Gorges reservoir area. During the operation of the red sandstone reservoir, the hydro-mechanical coupling characteristics affect the stability of most landslides and rock slopes. In this paper, triaxial compression tests under different confining pressures and osmotic pressures are carried out on the Jurassic red sandstone in the Three Gorges Reservoir area by means of the multi-field coupled triaxial test system. The mechanical properties and permeability evolution characteristics of the red sandstone under triaxial compression are systematically studied. The results show that: ①The pre-peak stress-strain curve of red sandstone can be divided into pore compaction stage, elastic deformation stage, stable development stage of micro-cracks, and unsteady development stage. The mechanical parameters of red sandstone are negatively correlated with osmotic pressure and positively correlated with confining pressure. ②With the increasing of confining pressure, the failure mode of red sandstone transitions from tensile failure to shear failure.③The permeability under different osmotic pressures shows a "three-stage" evolution law of developing steadily firstly, then increasing slowly and increasing sharply lastly; the permeability under different confining pressures decreases firstly and then increases. ④The effects of osmotic pressure and confining pressure on rock are analyzed from the perspective of energy, and the degradation effect of seepage inrock and the inhibition effect of confining pressure on crack development are verified. The experimental results have guiding significance for the stability of bank slope.In this experiment, the strength, deformation and permeability characteristics of the little-reported Jurassic red sandstone were systematically studied, which is of complementary significance to the topic of seepage-stress coupling. The working conditions are determined according to the stress level of the rock mass on the slope of the Three Gorges reservoir area, and the test results have guiding significance for analyzing the stability of the slope in the reservoir area.

This review article examines the crucial role of energy harvesting and energy recovery in the design of battery electric vehicles (BEVs) and fuel cell hybrid electric vehicles (FCHEVs) as these vehicles have limited onboard power sources. Harvesting energy and recovering energy from onboard systems can significantly improve energy efficiency, increase range, and reduce fuel consumption. The latest advances in vehicular energy recovery and harvesting, including regenerative braking, regenerative suspension, solar and wind energy harvesting, and other recovery methods are studied and the impact of the energy storage system and powertrain architecture on energy harvesting is investigated. Regenerative brake control strategies and driver behaviour’s effect on energy recovery are reviewed, and the potential of energy harvesting in electric vehicles is discussed, including experimental and low-power harvesting methods. The importance of using perception and navigation technologies in autonomous vehicles to enhance energy efficiency is highlighted. The article identifies critical research gaps, challenges, and future directions for research in this field. This review stands out from previous papers by covering overlooked subjects such as driver behaviour and deceleration planning in autonomous vehicles, low-power harvesting methods, and experimental techniques applicable to electric vehicles.

An isolation layer composed of isolators and steel dampers in base-isolated tall buildings can dissipate wind-induced energy via repeated elasto-plastic deformation. Its energy dissipation can be used to estimate its wind-induced responses and the fatigue damage in the steel dampers. Computationally costly time history analyses using multi-degree-of-freedom (MDOF) models suggest that some structural parameters influence the isolation-layer energy dissipation. However, using common single-degree-of-freedom (CS) models cannot fully capture such influences (e.g., those caused by the damping ratio and the natural period of the upper structure). Hence, this paper proposes a more accurate new equivalent single-degree-of-freedom (ES) model to estimate the isolation-layer energy dissipation in base-isolated tall buildings under strong winds. The ES model considers the influence of structural parameters and uses the first mode shapes of the MDOF models. It is as computationally efficient as, but is more accurate than, the CS model. The results indicate that it can estimate the isolation-layer energy dissipation as closely as MDOF models of base-isolated tall-building under strong winds.

In this paper, the influence of different fiber materials on the dynamic splitting mechanical properties of concrete was investigated. Brazil disc dynamic splitting tests were conducted on plain concrete, palm fiber-reinforced concrete, and steel fiber-reinforced concrete specimens using a split Hopkinson pressure bar (SHPB) test device with a 100 mm diameter and a V2512 high-speed digital camera. The Digital Image Correlation (DIC) technique was used to analyze the fracture process and crack propagation behavior of different fiber-reinforced concrete specimens and obtain their dynamic tensile properties and energy dissipation. The experimental results indicate that the addition of fibers can enhance the impact toughness of concrete, reduce the occurrence of failure at the loading end of specimens due to stress concentration, delay the time to failure of specimens, and effectively suppress the expansion of cracks. Steel fibers exhibit a better crack-inhibiting effect on concrete compared to palm fibers. The incident energy for the three types of concrete specimens is roughly the same under the same impact pressure. Compared with plain concrete, the energy absorption rate of palm fiber concrete is decreased, while that of steel fiber concrete is increased. Palm fiber-reinforced concrete and steel fiber-reinforced concrete have lower peak strains than plain concrete under the same loading duration. The addition of steel fibers significantly impedes the internal cracking process of concrete specimens, resulting in a relatively slow growth of damage variables.

Using the Split Hopkinson Pressure Bar (SHPB), a sequence of impact loading experiments were performed on sandstone to examine the dynamic constringent characteristics and crushing properties. The dynamic parameters, block size distribution, and energy characteristics of sandstone under various loading rates were obtained. The damaged sandstone was screened using a standard sieve and the particle size distribution curve conforming to the Rosin-Rammler distribution was discovered. On account of fractal theory, dynamic parameters, fractal dimension and energy characteristics of sandstone after splitting failure were constructed concerning the distribution of broken size. The results show that: the fragment size distribution of damaged sandstone complies with the geometric fractal law. As the loading rates increase, the fractal dimension of impacted fragments increases and the average fragment size decreases. The specimen’s energy dissipation density is a power function related to the fractal dimension, which is negatively associated with the average fragment size of the specimens. The research findings of this paper have necessary implications for rock-crushing engineering applications.

Modern protective materials must not only exhibit an intelligent response behavior, but also possess an excellent energy absorption ability. The applicability of shear-stiffening gel is limited because it generally cannot demonstrate good shape stability, strain sensitivity, and energy dissipation ability simultaneously. In this study, multiple hydrogen bonds and metal coordination bonds are incorporated into a shear-hardening gel to fabricate a new impact-hardening polymer (IHP-Cu) with multi-level energy dissipation pathways, thereby achieving a balance between shape stability, rapid self-healing, and energy dissipation. IHP-Cu maintains a stable shape in its natural state, exhibits significant strain-sensitive behavior at different strain rates, and supports a weight of 400 g at room temperature for 10 s after damage. In compression cycling tests, its energy absorption efficiency exceeded 90%. In the frequency-dependent test (strain rate of 0.1 s−1), its elastic work and viscous dissipation increased by 24 and 12.5 times, respectively, compared to those of the conventional shear-hardening gel. This paper also reveals the energy dissipation mechanism of IHP-Cu, thus providing a theoretical basis and reference for the development and optimization of new protective materials.

This paper seeks to examine the plastic deformation and seismic structural response of a mega-subcontrolled structural system (MSCSS) subjected to strong seismic excitations. Different MSCSS configurations were modeled with nonlinear finite elements, and nonlinear dynamic analyses were performed to examine their behaviors. This paper introduces a novel and optimized MSCSS configuration, configuration 30, which demonstrates remarkable results for the reduction of plastic strain. Utilizing a steel plate shear wall enhances the seismic structural integrity of this system (SPSW). This configuration improved the mean equivalent plastic strain of columns and beams by 51% and 80%, respectively. In addition, a comparison between unstiffened and ring-shaped infill panels of SPSWs demonstrates that ring-shaped infill panels offer greater lateral stiffness and energy dissipation with a 44% reduction in maximum equivalent plastic strain. Compared to configuration 1, configuration 30 exhibited the most controlled structural response, as the minimum residual story drift improvement was 70% in the first, second, and third substructures, respectively, and the maximum coefficient of variation (COV) was 16% and 32% in the acceleration and displacement responses, respectively.

Abstract The spillways are one of the most important hydraulic structures used in river engineering, dam construction, irrigation, and drainage engineering projects. Recently, a new type of such spillways with a circular crest has been proposed. In this paper, the hydraulic properties of the circular crested stepped spillway (CCSS) including flow pattern, distribution of velocity on the crest and pressure, turbulence intensity, discharge coefficient ( $${C}_{d}$$ C d ) and energy dissipation ratio (EDR) were investigated numerically. To model the free surface of flow the volume of fluid technique, and for modeling the turbulence of flow, k − ε (RNG) was utilized. Results declared that there is a good agreement between the laboratory observations and numerical simulation. The $${C}_{d}$$ C d of the CCSS changes between 0.9 and 1.4 considering the range of relative upstream head ( $${h}_{up}/R$$ h up / R ) between 0.33 m and 2.67. The observation of the flow streamlines showed that they are tangential to the curvature of the crest and there is no separation of the flow from the crest. Examination of the pressure distribution on the CCSS model shows that just downstream part of the crest, the pressure is partially negative. Of course, the same partial negative pressure is observed on the edge of the steps. The steps increase the maximum intensity turbulence by 50%. The CCSS can dissipate the energy of flow between 90 and 30%, and in the skimming flow regime, the portion of each step in the energy dissipation regardless of their position is almost identical.

Rock joints exhibit hysteresis shearing behavior and produce energy dissipation under shear cyclic loads, which however cannot be accurately depicted by existing constitutive models. This paper establishes a constitutive model for hysteresis shearing and associated energy dissipation of rock joints. Analytical expressions of the model during cyclic shearing processes are derived. Derivation of the model indicates no energy dissipation in the elastic stage. When the shear load exceeds elastic boundary, nonlinear energy dissipation takes place. Validations with experiments show that the proposed model provides good conformities with direct shear curves and hysteresis loops, and can predict the energy dissipation characteristics of rock joints under different working conditions. Compared to the constitutive models using Weibull’s distribution, the proposed one is smooth at the elastic boundary and can accurately capture the maximum shear stress. Unlike the existing incremental-type models, the proposed one provides clear and direct analytical expressions for both shear stress and energy dissipation during the whole displacement domain, which is more convenient in application.

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 paper presents a study on the seismic performance of rectangular hollow section (RHS) X-joints subjected to in-plane bending moment (IPBM). The study began by testing two RHS joint specimens with varying brace-to-chord width ratios (β) under quasi-static cyclic IPBM loading. The results showed that the final failure mode of the specimen with the large β value (β = 1.0) is the tearing of the weld near the brace root, while the specimen with the medium β value (β = 0.83) failed due to the tearing of both the weld and the adjacent chord face. The seismic performance of the X-joints depended considerably on the β value. The increase in β remarkably improved the strength of the X-joints but at the cost of energy dissipation capability, deformability and ductility. Our experimental results also demonstrated that the current code equations remarkably underestimate the flexural strength of RHS X-joints, while the modified equations that take the weld size into account can predict it well. In addition, the reason behind the experimental observation can be further explained by FE analysis and the proposed elastic-support plate analytical model.

Long-term extraction of sand from a river causes large mining pit on the river bed, and these pits change their fluvial processes. In this paper, an experimental study is executed to interpret the turbulence flow structure in a mining pit. This research mainly focuses on the fractal dimension of velocity fluctuations and Reynolds shear stress (RSS) of flow in the longitudinal and vertical plane for a mining pit region. The results show that the magnitude of fractal dimension for velocity fluctuation and RSS is smaller in the mining pit than the upstream and downstream of the pit. The large values of fractal dimensions at the pit downstream show an increase in flow roughness. It is found that the Taylor microscale decreases towards the channel bed, and this is because of increasing turbulence dissipation near the bed region. We have observed a significantly lower value of Taylor microscale in the mining pit. The higher value of the Taylor microscale is found far downstream of the pit. Nondimensional turbulence mixing length shows a decrease in the traversing length of an eddy at the far downstream of the pit. HIGHLIGHTS We calculated the fractal dimension and turbulence scale in a mining pit.; Fractal dimension is less inside the pit as contrast to downstream of the pit.; The study shows that Taylor microscale increases at the pit downstream.; For sustainable management of sand mining operation, a detail understanding of the flow characteristics is required.;

Abstract Recently, new materials and methods have been implemented to improve the performance of reinforced concrete columns. This paper studies experimentally the behavior of reinforced high-strength columns, with additional internal confinement using hexagonal chicken wire mesh (HCWM) to enhance ductility, energy absorption, and ultimate strength and reduce the brittleness of traditional columns. Eight double-ended one-third-scale columns with different volumetric ratios of transverse rebar have been constructed and loaded under the uniform axial compression and lateral cyclic loads. Different volumetric ratios of transverse rebar were provided based on special, intermediate, and ordinary moment frames specifications of ACI 318–14 (named SD, ID, and OD, respectively). The specimens were confined by transverse rebars and HCWM and the results were compared with reference specimens with traditional transverse ties. Experimental findings demonstrated that HCWM specimens exhibited better performance compared to their control specimens concerning crack control efficiency, load capacity, ductility, energy dissipation, and failure modes. Implementation of HCWM increased the ultimate deformation, ductility, and energy absorption of OD specimens up to 21%, 50%, and 175%, respectively, compared to their control specimen. Confinement of the concrete columns by HCWM increased the ultimate strength of OD and ID specimens up to 15% and 22% under the cyclic load, but has a negligible effect on SD columns due to enough ratio of transverse and longitudinal rebars in SD specimens. As a result, confinement of specimens by HCWM could be regarded as a simple and effective method to improve the seismic characteristics of RC columns, particularly those members constructed with a minimal number of transverse rebars.

This paper reports the experimental investigation conducted to study the influence of temperature and rest period on different methods of estimation of fatigue life of the bituminous mixture. Four-point beam bending tests were conducted on the bituminous mixture prepared with one unmodified binder and two different modified binders (crumb rubber modified and elastomer modified binder). The test was conducted at 20 °C and 0 °C using continuous loading and a rest period between two load cycles. The fatigue life was estimated using stiffness modulus and energy dissipation. The performance of three different bituminous mixtures was ranked—ranking a bituminous mixture based on the fatigue performance varied with temperature and loading condition. In addition, the ranking also varied with different post-processing methods adopted.

Abstract How particles are being energized by turbulent electromagnetic fields is an outstanding question in plasma physics and astrophysics. This paper investigates the electron acceleration mechanism in strong turbulence (δB/B0 ∼ 1) in the Earth's magnetosheath based on the novel observations of the Magnetospheric Multiscale mission. We find that electrons are magnetized in turbulent fields for the majority of the time. By directly calculating the electron acceleration rate from Fermi, betatron mechanism, and parallel electric field, it is found that electrons are primarily accelerated by the parallel electric field within coherent structures. Moreover, the acceleration rate by parallel electric fields increases as the spatial scale reduces, with the most intense acceleration occurring over about one ion inertial length. This study is an important step toward fully understanding the turbulent energy dissipation in weakly collisional plasmas.

The blisks and labyrinth seals in gas turbine engines are typical rotating periodic structures. Vibration problems will inevitably occur during the operation, which can easily lead to High Cycle Fatigue failure of the structure. Adding ring damper is an effective means of structural vibration reduction. The damper uses the dry friction of the contact surface to dissipate the vibration energy, improve the damping of the system, and then reduce the vibration response of the structure. The structures have a nodal diameter and modal shape, and the forced vibration often presents the characteristics of traveling wave. In this paper, an evaluation method for dry friction damping of ring damper under the axial component of traveling wave vibration is established. For the given vibration stress at the critical location, the equivalent damping ratio provided by the ring damper is calculated based on the friction energy dissipation and the damping characteristic curve that is the equivalent damping ratio varying with the vibration stress is obtained. This method can avoid calculating the nonlinear dry friction forced response and is suitable for the design stage. The damping of split ring dampers with rectangular section for one blisk and labyrinth seal is analyzed in this paper. It is shown that rotating speed, friction coefficient, section area and material density significantly influence the damping characteristics. There are many factors affecting the damping characteristics of the damping, so it is necessary to comprehensively consider various factors and multiple modes for vibration reduction design.

Chaotic process in wave passing through pores on the attached fishing net between twin pontoons of floating breakwater (TPFB) may lead to several severe problems relating to the hydrodynamic performance of such coastal structure. In presence of relatively fine pores, the wave transmission coefficient (Kt) tends to diminish while the reflection coefficient (Kr) will likely increase, or vice versa for coarse ones. The circumstance requires a complete design optimization study into obtaining an optimum porosity. This paper presents optimization on the fishing net porosity (n) of TPFB using artificial intelligence (AI) model. Here, a multi-objective evolutionary algorithm with various genetic parameters is proposed to search for optimum n ratio through primarily minimizing transmission (Kt) and reflection coefficients (Kr) while maximizing energy dissipation coefficient (Kd). In addition, a computational fluid dynamic (CFD) programme is developed using an extended Reynolds Average Navier-Stokes (RANS) solver for a solid-permeable obstacle. Several parameters such as wavelengths and porosity ratios including a set of optimization criteria, have been taken into account in the simulation, where the optimum solution is then selected from various populations. Meanwhile, the optimum result will be qualitatively evaluated, in which it is visualized by the characteristic patterns of induced energy dissipation. The results revealed that the optimization algorithm is effectively capable of determining global trade-offs between Kt, Kr, and Kd. As compared to the existing model, Kt and Kr decrease to less than 0.85 and 0.42 respectively, whereas Kd was increased up to 0.34 resulting in optimum hydrodynamics of TPFB indicated by further enhancement in the rate of energy dissipation across TPFB entanglement. For validation, the numerical model can fairly simulate well on the hydrodynamics of structure.

In this paper, the effects of different combinations of permeable spur dikes installed in the bend section of spillway on flow characteristics and energy dissipation rate were experimentally and numerically investigated. The results indicate that the permeable spur dikes installed in the spillway bend appreciably contributes to the improvement on the water surface uniformity, and the water surface uniformity can reach 90.13% with three permeable spur dikes installed in the bend. The permeable spur dike can lead to different degrees of decrease in the time-averaged longitudinal velocity in each zone of spillway bend. Different from previous study, no circulation zone is formed upstream and downstream of permeable spur dike due to the presence of permeable holes, and the flow upstream of permeable spur dikes could be divided into three distinctly different flow modes according to dye tracing. The presence of permeable spur dikes causes the concentration of TKE zone at concave bank of the spillway bend, except for TKE zone immediately next to the bottom plate. The TKE first increases and then decreases with the increase in the vertical distance from the bottom plate of the spillway bend, exhibiting a typical parabolic distribution. The energy dissipation rate in the spillway bend with permeable spur dike was calculated using a modified integral method, and the dissipation rate can reach as high as 21.08% with three spur dikes installed in the bend. HIGHLIGHTS Permeable spur dike was proven to be able to improve the flow characteristics in spillway.; Up to 20% energy dissipation rate can be achieved by using permeable spur dike in spillway.; The distribution of velocity in spillway with permeable spur dike was obviously decreased.; The arrangement of three permeable spur dikes has the best effect on improving the flow characteristics of spillway.;

This paper aims to modify the conventional one-coefficient instantaneous acceleration-based (IAB) model for better prediction of unsteady friction behavior. In this work, the energy dissipation caused by viscous stress during fluid volume compression–expansion (CE) was derived from the compressible Navier–Stokes equation. It is found that the energy dissipation term can be expressed by the product of the second-order partial derivative of velocity in space and the second viscosity coefficient. On this basis, a modified IAB-CE model was developed with the energy dissipation term and solved by the method of characteristic (MOC). The numerical results obtained from the modified model showed a good agreement with the four test cases, where the relative errors are improved by 0.26, 2.03, 9.56, and 36.67%, compared with the results from the original IAB model. The estimation for wave peak and valley is improved as well. Furthermore, the Bradley equation can be applied to establish the relationship between the dissipation coefficient and the Reynolds number. The modified model developed in this study takes into account the fluid CE effects and improves the prediction accuracy of wave amplitude of unsteady flow. HIGHLIGHTS The numerical investigation of unsteady pipe flow with an efficient one-coefficient model.; The fluid compression–expansion effect was considered in the energy dissipation term.; The dissipation coefficient and the Reynolds number conform to the Bradley equation.; The wave amplitude prediction of friction flow was improved by the modified IAB-CE model.;

In the present paper, an optimization procedure is proposed for stepped spillway design dimensions, which leads to maximum energy dissipation rate and minimum construction cost, considering independently the chute cost and stilling basin cost. Three independent objective functions are thus simultaneously satisfied. The procedure involves four main tools: the multi-objective particle swarm optimization method (MOPSO) to find Pareto solutions in one run, the K-means clustering algorithm to reduce the size of the obtained non-dominated solutions, the pseudo-weight vector approach (PWV) to facilitate the decision making and to select some adequate solutions, and finally, CFD simulations to analyze the retained optimal solutions. The suitability of the proposed procedure is tested through an example of application. As results, a set of 20 solutions with different satisfaction levels is found and compared to existing solutions. A multi-objective optimization problem may have many different solutions; the originality of the present work lies in the proposed procedure, which explores several possible solutions and reduces their number to give help to the decision making. Furthermore, an approximate expression of spillway total cost is also derived as a function of flow energy dissipation rate. HIGHLIGHTS A novel procedure is proposed for stepped spillway design optimization.; Three objective functions are minimized: the rate of residual energy, the chute construction cost, and the stilling basin construction cost.; MOSPO, K-means algorithm, pseudo-weight vector approach, and CFD are implemented.; An expression of the total construction cost as a function of flow energy dissipation rate is derived.;

Viscoelastic (VE) dampers show good performance in dissipating energy, being widely used for reducing vibration in engineering structures caused by earthquakes and winds. Experimental studies have shown that ambient temperature has great influence on the mechanical behavior of VE dampers. Therefore, it is important to accurately model VE dampers considering the effect of temperature. In this paper, a new fractional-order Zener (AEF-Zener) model of VE dampers is proposed. Firstly, the important influence of fractional orders on the energy dissipation ability of materials is analyzed. Secondly, an equivalent AEF-Zener model is developed that incorporates the ambient temperature and fractional-order equivalence principle. Finally, the chaotic fractional-order particle swarm optimization (CFOPSO) algorithm is used to determine the model’s parameters. The accuracy of the AEF-Zener model is verified by comparing model simulations with experimental results. This study is helpful for designing and analyzing vibration reduction techniques for civil structures with VE dampers under the influence of temperature.

Scale properties and energy dissipation in the turbulent energy transfer process play an important role in deeply understanding the features of ocean turbulence. In this paper, a universal multifractal cascade model is applied to investigate scale and intermittency properties of a turbulent flow, and two sets of measured turbulence datasets in horizontal and vertical directions are performed for comprehensive experimental verification. First, an empirical mode decomposition method is utilized to adaptively decompose microstructure shear time series into several intrinsic mode functions. Then, the multifractal spectrum is calculated to extract multifractal features for different time scales. The ocean microstructure field shows an asymmetric structure with a left truncation and a long right tail in different directions. This proves that most energy transfer processes occur on small scales. Finally, the calculated multifractal indexes of all intrinsic mode functions for two datasets show that the intermittency of turbulence decreases with the increase in time scales, which reflects the multifractal intensity and the level of intermittency of turbulence. The multifractal cascade model can successfully build a bridge between intermittency and dissipation in the multiscale energy cascade process.

In response to the growing demand for high-strength and high-toughness materials in industries such as aerospace and automotive, there is a need for metal matrix composites (MMCs) that can simultaneously increase strength and toughness. The mechanical properties of MMCs depend not only on the content of reinforcing elements, but also on the architecture of the composite (shape, size, and spatial distribution). This paper focuses on the design configurations of MMCs, which include both the configurations resulting from the reinforcements and the inherent heterogeneity of the matrix itself. Such high-performance MMCs exhibit excellent mechanical properties, such as high strength, plasticity, and fracture toughness. These properties, which are not present in conventional homogeneous materials, are mainly due to the synergistic effects resulting from the interactions between the internal components, including stress–strain gradients, geometrically necessary dislocations, and unique interfacial behavior. Among them, aluminum matrix composites (AMCs) are of particular importance due to their potential for weight reduction and performance enhancement in aerospace, electronics, and electric vehicles. However, the challenge lies in the inverse relationship between strength and toughness, which hinders the widespread use and large-scale development of MMCs. Composite material design plays a critical role in simultaneously improving strength and toughness. This review examines the advantages of toughness, toughness mechanisms, toughness distribution properties, and structural parameters in the development of composite structures. The development of synthetic composites with homogeneous structural designs inspired by biological composites such as bone offers insights into achieving exceptional strength and toughness in lightweight structures. In addition, understanding fracture behavior and toughness mechanisms in heterogeneous nanostructures is critical to advancing the field of metal matrix composites. The future development direction of architectural composites and the design of the reinforcement and toughness of metal matrix composites based on energy dissipation theory are also proposed. In conclusion, the design of composite architectures holds enormous potential for the development of composites with excellent strength and toughness to meet the requirements of lightweight structures in various industries.

Quantum-dot cellular automata (QCA) are a promising nanoscale computing technology that exploits the quantum mechanical tunneling of electrons between quantum dots in a cell and electrostatic interaction between dots in neighboring cells. QCA can achieve higher speed, lower power, and smaller areas than conventional, complementary metal-oxide semiconductor (CMOS) technology. Developing QCA circuits in a logically and physically reversible manner can provide exceptional reductions in energy dissipation. The main challenge is to maintain reversibility down to the physical level. A crucial component of a computer’s central processing unit (CPU) is the arithmetic logic unit (ALU), which executes multiple logical and arithmetic functions on the data processed by the CPU. Current QCA ALU designs are either irreversible or logically reversible; however, they lack physical reversibility, a crucial requirement to increase energy efficiency. This paper shows a new multilayer design for a QCA ALU that can carry out 16 different operations and is both logically and physically reversible. The design is based on reversible majority gates, which are the key building blocks. We use QCADesigner-E software to simulate and evaluate energy dissipation. The proposed logically and physically reversible QCA ALU offers an improvement of 88.8% in energy efficiency. Compared to the next most efficient 16-operation QCA ALU, this ALU uses 51% fewer QCA cells and 47% less area.

The addition of superelastic shape memory alloy fibers (SMAF) into engineering cementitious composites (ECC) can create a new type of SMAF-ECC composite material with good self-recovery and energy dissipation performance, which is very suitable for seismic structures. In this study, 10 groups of beam specimens with different volume contents of SMAF were fabricated, and the bending performance, deflection recovery and energy dissipation ability of these beams were studied through three-point bending cyclic loading tests. The failure mode, peak load, load–deflection curve, crack width and other indicators of the specimens were analyzed, and the relationship expression between fiber content and bending strength was established by fitting analysis. The results show that adding SMA fibers can significantly improve the peak load of ECC beams, with a maximum increase of 48.31%. The knotted SMA fibers can fully exert their superelasticity, providing the beam specimens with crack self-closing and deflection recovery ability. When the volume content of SMA fibers is 0–0.6%, the bending strength, energy dissipation ability and deflection recovery ability of the composite material beams increase with the increase in fiber content. When the volume content of SMA fibers is 0.6–1.0%, the above indicators decrease with the increase in fiber content. The suggested equations can well reflect the relationship between fiber content and beam bending strength. The research results of this paper provide theoretical support for the engineering application of SMAF-ECC composite materials.

In this paper, a tesla-shaped emitter is proposed based on the structure of the “tesla valve” as the source of inspiration, so that the water flow in the channel would produce a variety of energy dissipation phenomena, such as diversion, hedging, and mixing, to explore the hydraulic performance and energy dissipation mechanism of the tesla-shaped emitter. The channel structure parameters were taken as factors, and 16 groups of orthogonal tests were arranged. Based on CFD technology, the pressure–flow relationship curve slope, flow ratio between the main channel and secondary channel, flow field, and head loss of the emitter were calculated and analyzed for different combinations of structural parameters. Based on a significance level α = 0.05 test, the main channel inlet section length (L3) had a significant impact on the curve slope, and the secondary channel length (L1) and main channel inlet section length (L3) had a significant impact on the flow. The multiple linear regression mathematical models between the channel structure parameters and the curve slope and the flow were constructed. The larger the ratio between the main channel and the secondary channel flow, the better the hydraulic performance of the emitter. The channel unit loss coefficient increased linearly with the increase of the emitter inlet pressure, and its value ranged from 4.5769 to 8.1716, with an excellent energy dissipation effect. The hedge mixing of the water flow was the core of the energy dissipation of the tesla-shaped emitter. By appropriately increasing the inlet size of the main channel and other elements to increase the main channel flow and optimize the flow ratio between the main channel and the secondary channel, the mixing was improved, which consequently improved the hydraulic performance of the emitter.