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An equivalent fluid model based finite-difference time-domain algorithm is proposed to simulate the frequency characteristic of porous material with rigid frame. The rigid-frame porous material is replaced by an equivalent fluid characterized by the effective density and the effective bulk modulus, which reflect the viscous effects and thermal effects in the porous material, respectively. The effective density and the effective bulk modulus are frequency-dependent complex values, which are designed in the form of infinite impulse response filters in the frequency domain. The Z transform theory is used to discretize the frequency-domain wave equations. The accuracy of the proposed algorithm is preliminarily validated by good agreement between the calculated and measured normal-incidence sound absorption coefficients of two samples composed of different multiple-layered materials in a wide frequency range.

The authors proposed a reinforced concrete slab bridge with H-shaped steels which has high load-carrying capacity in order to reduce the construction cost. Our past study clarified that H-shape steels without stud dowel and concrete could compose hybrid section and static load was equally distributed each H-shaped steel in elasticity stage. Considering the described above it is possible to design this type of bridge as composite. Moreover it clarified that the cyclically loaded this type bridge has the high fatigue capacity and load-carrying capacity as same as the statically (non- cyclically) loaded that bridge. As next step the authors proposed a reinforced concrete slab rigid frame bridge with H-shaped steels in order to reduce the maintenance cost and to increase seismic performance. Especially the rigid connection method of H-shaped steel and re-bar in the abutments was proposed. Then the static loading test was carried out to grasp load-carrying capacity. As the results of the experiment destructive behavior of the reinforced concrete slab rigid frame bridge with H-shaped steels was clarified and also the validity of the connection method was clarified.

An experimental program was conducted to evaluate the seismic performance of rigid frames strengthened with externally bonded CFRP fabric and near-surface mounted (NSM) CFRP bars. Three rigid frame specimens were subjected to cyclic loading. The three specimens were identical in size and internal reinforcement. One specimen served as control while the other two specimens were strengthened using CFRP fabric and NSM bars such that they have equivalent capacity at first yielding. CFRP wraps were used on the strengthened specimens to anchor the main CFRP sheets and NSM bars and to prevent/delay debonding of the FRP reinforcement. Test results indicated that both techniques delay the yielding of the internal steel reinforcement and result in an increase in the flexural strength of the members, an increase in energy dissipation , and a decrease in stiffness degradation . However, the load-deflection response for both strengthening techniques flattens shortly after yielding of internal steel due to localized debonding of the fabric and the bars, unlike monotonic loading which typically shows post-yielding stiffness. Results also showed that strengthening with CFRP fabric results in fewer cracks, more energy dissipation, and less strength degradation after yielding than strengthening with NSM bars where the latter results in higher ultimate strength.

The frame-truss composite wall is a wall assembled by a certain number of resistance unit composed of outer frame and internal diagonal struts . As the primary energy dissipation unit of the system, the resistance unit should be studied in the perspective of internal force analysis. When the internal force of resistance unit is analyzed, the outer frame and the internal diagonal struts are regarded as composite members of reinforced concrete. According to the characteristics of resistance unit, the outer frame is regarded as a rigid frame and the internal diagonal struts are treated as struts hinging with the rigid frame and mainly subjected to axial force . So the simplified model is formed and it can be regarded as seven-degree statically indeterminate structure in mechanics. The internal forces of outer frame and internal diagonal struts corresponding to the constraint forces of simplified model can be calculated by solving the statically indeterminate problem. The ABAQUS model of resistance unit is established to simulated the performance so that the internal force can also be obtained in another way. The constrain force of simplified model and the internal force of ABAQUS model are comparatively analyzed and the results show a feasibility of simplified model. The phenomenon of cracks on diagonal struts and ultimate failure state of resistance unit are compared with the stress cloud of ABAQUS model to explains the reasonability of simplified model. The applicability of ABAQUS model is further stated by comparing the stress of longitudinal rebar on the most dangerous section between the simplified model and ABAQUS model for the resistance unit. This simplified model can provide a method to analyze the internal force of the resistance unit under external load, which also lays a foundation for the subsequent researches.

This paper analyzes different types of failures in buildings of the cities of Portoviejo, Manta and Bahia de Caraquez during the earthquake of April 16, 2016. The evidence derived from the failures refer to existing codes and design considerations in order to reveal how modeling corresponds or not with different reinforced-concrete columns, floor slabs and rigid frame buildings without structural walls. Given the diversity of constructive solutions found in the steel-deck slabs, a 23 factorial experiment design was performed to identify the influence and independence of the type of node, the rectangularity of the floor plan and the height of buildings on the strength and deformation parameters of floor slabs, in relation to the failures observed. Additionally, this paper undertakes a singular analysis approach of different failure causes in a building demolished in the city of Portoviejo, based on evidence revealed by the earthquake, and described some of the distinctive features of this type of study.

The unstable change of early temperature field during concrete curing of box girder could lead to the thermal deformation and autogenous shrinkage deformation of concrete, make the concrete crack early, and even affect the subsequent mechanical performance. In order to study the variation law of the early-age temperature field of the box girder concrete and to seek the method to control the variation of the temperature field of the box girder concrete, the No.0 box segment with the most complex structure and the largest volume in the bridge was selected as the research object. The early-age temperature field of No.0 box segment after pouring was simulated by Midas/FEA and the correctness of the simulation was verified by field measurement. Then the time-history law of early-age temperature field of the box girder under the coupling effect of hydration heat and ambient temperature was studied, and the time-history law of the early-age temperature field of the box girder was investigated by changing different concrete curing parameters. The results show that the larger the local size is, the larger the temperature difference is. The selection of formwork's material and thickness should integrate the factors of formwork bearing capacity and thermal insulation performance. The reasonable selection of formwork can effectively control the core temperature and the temperature difference between the inside and outside of the box girder. Formwork installation temperature and wind velocity have a great influence on the temperature difference between the inside and outside of the box girder. The research results can provide technical support for controlling the early-age temperature field changes of box girder concrete, be used to provide a theoretical basis for the best selection of formwork and the selection of the best concrete curing conditions, and help to improve efficiencies in the uses of human capital, energy, and building materials in engineering construction.

Lateral load resisting systems (LLRS) in reinforced concrete (RC) buildings should be adequately determined to control their response under lateral and gravity loads. Practitioners used to select the LLRS using one-step analysis (OSA) by assuming both the lateral and gravity loads are applied at one stage to a complete building. Instead, staged-construction analysis (SCA) should be adopted because RC buildings are constructed in different stages and the gravity loads act sequentially. In this research, a nonlinear finite element model for SCA of RC buildings is developed and validated using a robust commercial software. The developed model is extended to account for time dependent effects (SCAT) such as shrinkage, creep, and strength gain. The model is utilized to analyze eight RC buildings with different heights and LLRS. Design parameters for the studied buildings are proportioned to satisfy both the working and ultimate state design criteria. Differential displacements and straining actions in horizontal elements as well as shortenings in vertical elements are estimated using SCAT and then compared to their counterparts obtained from OSA. SCAT yielded shortening and differential displacements larger than those obtained from OSA by a percentage that reached 143%, 153%, 116%, and 154% for buildings with rigid frame, shear wall, wall-frame, and tube in tube LLRS, respectively. Increase in straining actions obtained from SCAT ranged between 26% and 554% more than those obtained from OSA. Decrease in straining actions obtained from SCAT ranged between 26% and 71% less than those obtained from OSA.

In this paper, a dynamic model is adopted to investigate the stability and response characteristics of a vibrating system driven by four vibrators placed on two different rigid frames (RFs). Using the equations of motion of the system derived, the conditions for synchronization and stable operation of the system are studied by the average method and Hamilton’s rules, respectively. Based on the theoretical results obtained, some factors are further studied concerning the stable phase differences (SPDs), the coefficients for ensuring stability, and the vibration amplitudes of the two RFs in different resonant regions. These serve to reveal the stability and response characteristics of the system that determine the ultimate function of the vibrating machine. Finally, numerical simulations are carried out to examine the validity of the theoretical methods and numerical qualitative results. Based on the results from the theory and simulation analyses, it is suggested that the working region of the system should be selected in the sub-resonant region corresponding to the natural frequency (NF) of the main vibrating system in the [Formula: see text]- and [Formula: see text]-directions. In this case, the ideal relative circular motion for two RFs with a well isolation effect can be achieved, and the energy is saved.

The Real Time BeiDou Navigation Satellite System (BDS) has evolved into a reliable technique to detect both the three-dimensional magnitudes and frequencies of displacement of structures. BDS technology is exactly what monitoring needs for the bridge deformation. Also, the oscillations and damage severity can be evaluated and classified according to the dynamic bridge characteristics obtained from BDS. The intention of the present work is to demonstrate the use of BDS to provide data for the assessment of existing structures safety. The raw data were collected continuously over a period of 24 h at a minimum rate of 1 Hz. The collected data include traffic flow (for load estimation) and environment factors (such as wind speed, wind direction, relative humidity and temperature). The vibration frequencies are also measured from BDS data and compared with those given in the literature. The results of all the experiments proved to be very encouraging, and showed that the performance of BDS as it has developed in recent years, and that the BDS is reliably in quantifying both environmental induced bridge vibrations and high-frequency transient motion caused by vehicle loading, in particular changes of mass associated with changes in traffic loading are observed, providing the ability for verification and/or improvement of bridge design and modelling.

The aim of active casing is to reduce device noise generated to the acoustic environment by controlling vibrations of the walls of the device casing. The article concerns theoretical modelling of an active casing composed of six walls mounted to a rigid frame. The casing is considered as a complex coupled vibro-acoustic system, where the walls are excited by the acoustic field inside the casing, and by actuators bonded to the walls and used for active control. The acoustic field inside the casing is, in turn, formed by the noise originating from the device itself, and the secondary sound generated by all vibrating walls. The structure of such system is described in detail and, after being represented as interconnected subsystems, its state-space model is developed. The model includes fluid loading effect and imperfect fastening of wall edges to the frame. The system of coupled partial differential equations, subject to defined boundary conditions, is reformulated as an abstract first order evolution equation in an appropriate infinite dimensional function space. All assumptions and the structure of the model are chosen to make it useful for the purpose of control. In particular, the model can be used for analysis of controllability and observability of the whole casing as a vibro-acoustic system and, based on that, for optimisation of placement of actuators and structural sensors to efficiently reduce noise over required frequency band. On the basis of the obtained state equation, a block diagram of the system is constructed. It shows the structure of the whole system and the nature of interactions occurring between distinguished subsystems.

This article examines the theoretical and experimental aspects of specific types of tensile-braced mid-span steel plate shear walls and the effects of circular opening on the system. The mid-span implementation of shear walls is meant to avoid the need for strengthening the surrounding principal columns. This study was conducted on a rigid frame. The shear wall system is designed and manipulated in the middle of the frame and the bearings are modelled on that in detail. A related system was made in the laboratory scale 80 ∗ 80 cm and cyclic loading is applied to the system. Cyclic loading is gradually applied with a hydraulic jack, considering fully the amount of allowable and final drifts by evaluating the amount of strain and displacement of critical points by installed strain gauges and LVDTs. The results indicate appropriate and acceptable behaviour of the system even in high levels of drift. Finally, the model was designed on the basis of the finite element method to authenticate the experimental results that confirm the system's efficiency.

International audience; A method to characterize macroscopically homogeneous rigid frame porous media from impedance tube measurements by deterministic and statistical inversion is presented. Equivalent density and bulk modulus of the samples are reconstructed with the scattering matrix formalism, and are then linked to its physical parameters via the Johnson–Champoux–Allard–Lafarge model. The model includes six parameters, namely the porosity, tortuosity, viscous and characteristic lengths, and static flow and thermal permeabilities. The parameters are estimated from the measurements in two ways. The first one is a deterministic procedure that finds the model parameters by minimizing a cost function in the least squares sense. The second approach is based on statistical inversion. It can be used to assess the validity of the least squares estimate, but also presents several advantages since it provides valuable information on the uncertainty and correlation between the parameters. Five porous samples with a range of pore properties are tested, and the pore parameter estimates given by the proposed inversion processes are compared to those given by other characterization methods. Joint parameter distributions are shown to demonstrate the correlations. Results show that the proposed methods find reliable parameter and uncertainty estimates to the six pore parameters quickly with minimal user input.

Separated probe-forming systems can be applied to enhance the resolution of a scanning nuclear microprobe with a comparatively large working distance to accommodate the detectors at backward angles. In such systems, magnetic quadrupole lenses are placed at the considerable distance and hence require their precise alignment with the beam axes. Violation of this requirement results in a considerable increasing of a spot size on the target for a constant beam current. Positioning of magnetic quadrupole lenses in a doublet can be implemented in a single-unit design, where a yoke and poles of two lenses are made from one piece of soft iron by precise electrical discharge machining. In a case of triplet, lens manufacturing as a single-unit has technological difficulties. A lens triplet configuration presented in this work comprises placement of three single magnetic quadrupole lenses in a single rigid frame. An approach to lens alignment by the magnetic field reconstruction method was developed and successfully realized.

An electrostatic quadrupole doublet lens system has been designed and constructed to provide strong, mass-independent focusing of 1–3 MeV ions to a 1 µm2 spot size. The electrostatic doublet consists of four sets of gold electrodes deposited on quartz rods that are positioned in a precision machined rigid frame. The 38 mm electrodes are fixed in a quadrupole doublet arrangement having a bore diameter of 6.35 mm. The coating process allows uniform, 360° coverage with minimal edge defects. Determined via optical interferometry, typical surface roughness is 6 nm peak to valley. Radial and coaxial alignment of the electrodes within the frame is accomplished by using a combination of rigid and adjustable mechanical supports. Axial alignment along the ion beam is accomplished via external manipulators. COMSOL Multiphysics® v5.2 and Propagate Rays and Aberrations by Matrices (PRAM) were used to simulate ion trajectories through the system.

Reactive aggregates are widely distributed throughout Japan. In the Noto region, andesite is widespread, which causes alkali-silica reaction (ASR) degradation in concrete structures. For the maintenance of local bridges, it is necessary to observe the expansion trends of cracking caused by ASR in health assessments. In this study, remote long-term monitoring of a four-span prestressed concrete (PC) rigid-frame bridge was performed to investigate the expansion of cracks by ASR. To evaluate the health of this degraded bridge, instead of focusing only on the locations of cracks, it was also necessary to monitor simultaneously the displacement behaviors over time of the bridge and to obtain the crack expansion trends, which could not be identified by regular visual inspections alone. Therefore, long-term monitoring and loading experiments using large vehicles are utilized to reveal the correlation between cracking due to ASR and displacement of the overall structure due to variations of diurnal temperature and the live load. As a result of the loading tests using test trucks, by long-term monitoring of the relationship between the temperature and the crack displacement due to ASR, the expansion trend of the crack due to seasonal variations was obtained. A particularly rapid growth trend from spring to summer was recognized. In addition, the vertical displacement of the Gelber hinge, which could be obtained from the inclination angle using the correlation between the inclination angle and the vertical displacement of the static loading tests, was estimated at approximately 30–40 mm during summer. Moreover, as another conclusion of the study, it was found that changes in diurnal temperature and the displacement behavior of the entire bridge had significant consequences on the types of crack expansion in this bridge.

Damping value has considerable influence on the dynamic and seismic behaviors of bridges. However, currently the constant damping ratios that are prescribed by most bridge seismic design codes can\'t truly represent the complicated damping character of actual structures. In this paper, a cyclic loading experiment was conducted to study the effect of stress amplitude on material damping of concrete to present an analyzing model of the material damping of concrete. Furthermore, based on the fundamental damping of structure measured under ambient vibration, combined with the presented stress-dependent material damping concrete, the seismic response of a bridge pier was calculated. Comparison between the calculated and experiment results verified the validity of the presented damping model. Finally, a modified design and analysis method for bridge was proposed based on stress-dependent damping theory, and a continuous rigid frame bridge was selected as the example to calculate the actual damping values and the dynamic response of the bridge under different earthquake intensities. The calculation results indicated that using the constant damping given by the Chinese seismic design code of bridges would overestimate the energy dissipation capacity of the bridge.

Thermal stress of a continuous rigid frame bridge, based on the temperature gradient in Chinese bridge gauge, using a finite element analysis (FEA) method was investigated. First of all, the temperature effect of the whole bridge was analyzed, and the correlation of the improved amplitude of temperature gradient and temperature effect were studied. It was found that there was a linear relationship with temperature stress and improved temperature. And then, the temperature effect of zero block was analyzed and the details of box girder temperature stress distribution investigated by utilizing the FEA method. It was concluded that temperature stress mainly distributed in the body surface; under the condition of the improvement of temperature field, the center temperature stress of zero block was improved about 60% and the end temperature stress of zero block was improved about 75%.

To determine the seismic applicability of a long-span railway concrete upper-deck arch bridge with concrete-filled steel-tube (CFST) rigid skeleton ribs, some fundamental principles and seismic approaches for long-span bridges are investigated to update the design methods in the current Code for Seismic Design of Railway Engineering of China. Ductile and mixed isolation design are investigated respectively to compare the structural seismic performances. The flexural moment and plastic rotation demands and capacities are quantified to assess the seismic status of the ductile components. A kind of triple friction pendulum (TFP) system and lead-plug rubber bearing are applied simultaneously to regularize the structural seismic demands. The numerical analysis shows that the current ductile layout with continuous rigid frame approaching spans should be strengthened to satisfy the demands of rare earthquakes. However, the mixed isolation design embodies excellent seismic performances for the continuous girder approaching span of this railway arch bridge.

The purpose of this study is to analyse life cycle embodied carbon emission of apartment buildings using probabilistic analysis method as a part of research for reduction strategy of building embodied carbon emission. To that end, the structures of apartment buildings were divided into wall structure, rigid frame structure, and flat plate structure, and major building materials in terms of carbon emissions were derived. The life cycle scenario including production stage, construction stage, maintenance step, and disposal stage of the major building materials was established for evaluating the life cycle embodied carbon emission of apartment buildings. Also, 443 residential building of 38 apartment buildings constructed in last 10 years are set as the sample of this study, then major factors are derived through the correlation analysis on the features of buildings and major building materials. Probability distribution on major building materials are constructed through a goodness of fit analysis by utilizing an amount information of major factors and major building materials. The probabilistic life cycle embodied carbon emission were analyzed by structure and plan type of apartment buildings using Monte Carlo Simulation.

본 연구에서는 접합부가 접착제로 일체화된 강절형 기둥-보 접합 시험편과 슬릿 가공한 보부재에 기둥부재와 일체화된 목질접합물을 삽입하고 핀으로 접합한 시험편을 제작하여 모멘트 저항성능을 검토하였다. 목질접합물은 GFRP로 보강한 적층판을 제작하여 사용하였다. 슬릿 가공된 보부재에 GFRP보강적층판을 삽입하고 핀으로 접합된 기둥-보 시험편들은 완전탄소성 모델 분석으로 산출된 특성치들이 대조군인 강판삽입형 기둥-보 시험편보다 20∼80% 낮게 측정되었다. 기둥부재와 보부재가 접착제로 일체화된 강절형 기둥-보 시험편은 초기잔류변형이 거의 관찰되지 않았으며, 강판 삽입형 접합부보다 38% 향상된 초기강성과 41% 향상된 소성률이 측정되었다.

This article presents a procedure for analyzing wind effects on the rigid frame bridges with twin-legged high piers during erection stages, taking into account all wind loading components both on the beam and on the piers. These wind loading components include the mean wind load and the load induced by the three turbulence wind components and by the wake excitation. The buffeting forces induced by turbulence wind are formulated considering the modification due to aerodynamic admittance functions. The buffeting responses are analyzed based on the coherence of buffeting forces and using finite element method in conjunction with random vibration theory in the frequency domain. The peak dynamic response is obtained by combining the various response components through gust response factor approach. The procedure is applied to Xiaoguan Bridge under different erection stages using the analytic aerodynamic parameters fitted from computational fluid dynamics. The numerical results indicate that the obtained peak structural responses are more conservative and accurate when considering the effect of each loading component on the beam and on the piers, and the roles of different loading components are different with regard to bridge configurations. Aerodynamic admittance functions are source of the important part of the error margin of the analytical prediction method for buffeting responses of bridges, and buffeting responses based on wind velocity coherence will underestimate the results.

Incremental sheet forming techniques, such as Single Point Incremental Forming (SPIF), have an appealing potential in rapid prototyping and processing low volume plastic sheet products. Fitting a conventional CNC milling machine to accomplish SPIF is easy and cheap: just design and assembly a rigid frame and manufacture a semi-spherical end punch. Nevertheless, polymeric SPIF parts have a lack of dimensional accuracy and surface quality because of springback and friction effects. This experimental work shows the influence of temperature and force on final dimension and surface finishing of PVC SPIF specimens. In order to produce a temperature and force variation, the following parameters are modified: punch material, spindle rotational speed and sense.

International audience; This study concerns the acoustic wave diffusion in fractional dimensional rigid porous media in the low frequency domain. An equivalent fluid model with a non-integer dimensional space is developed using the Stillinger-Palmer-Stavrinou formalism. A generalized lossy diffusive equation is derived and solved analytically in the time domain. The coefficients of the diffusion equation are not constant and depend on the fractional dimension, static permeability and porosity of the porous material. The dynamic response of the material is obtained using the Laplace transform method. Numerical simulations of a diffusive wave in porous material with a non-integer dimensional space are given, showing the sensitivity of the waveform to the fractional dimension. It is found that the attenuation of the acoustic wave is more important for the the highest value of the fractional dimension d. This result is especially true for resistive porous materials (low permeability value) and for large thicknesses.

Knowledge of several intrinsic material parameters is crucial to the modeling accuracy of sound propagation in porous media. This paper studies the performance of several popular acoustic prediction models used to invert key intrinsic parameters of rigid frame porous media such as characteristic lengths, permeabilities and median pore size. These prediction models along with acoustic surface impedance experimentally measured with a standard impedance tube setup are evaluated in an optimization process which is essentially a Bayesian estimator. The effect of the number of intrinsic parameters in the model, sample thickness and frequency range on the accuracy of the Bayesian estimator is studied. The quality of model predictions is characterized using quantitative measures such as mean, variance and the interdependence of the estimated parameters. This paper also discusses uncertainties of the intrinsic parameters and effect of these uncertainties on the accuracy of the acoustic parameter prediction.

In artificial molecular devices, flexible, linear chains typically exhibit very weak capability in inhibiting molecular motion. Herein, we describe the dynamic properties of a series of molecular turnstiles consisting of a rigid frame and a phenyl rotator flanked with linear alkoxymethyl substituents. The long, flexible substituents act as elastic baffles to inhibit the rotations of the rotator at medium to fast speeds on the NMR time scale. When the rotator moves slowly, the substituents become more relaxed, thus obtaining an opportunity to completely thread through the cavity of the turnstiles. These findings reveal a basic but missing correlation between steric hindrance and speed of motion for flexible, linear chains in dynamic molecular devices, thus opening up a new direction toward molecular machines with more elaborate dynamic functions.

The high-voltage battery represents the key component of electrified automotive drive-trains. State-of-the-art lithium-ion cells (LIC) are commonly used due to their high specific energy. The cells are stacked and reinforced by a rigid frame. In addition to mechanical loads during operation, this substructure must also withstand inherent stresses caused by the swelling of the cells. A mechanical failure of the frame results at best in a vehicle breakdown but may also cause a short-circuit and catastrophic thermal propagation in one or more cells. Here we propose a novel method to monitor cell modules in-operando based on the measurement of the cell impedance. There are various sensitivities of the impedance, such as regarding temperature or State-of-Charge, but, as will be shown, it is also influenced by external mechanical loads. Two experimental setups are conducted. First, a simple test is presented during which the phenomenon was initially observed. Secondly, another experiment is carried out to resolve the presumed sensitivity across relevant compression forces. The measurements confirm the initially observed phenomenon. Finally a brief perspective for an effective and industrializable monitoring system is given.

Robots for underwater exploration are typically comprised of rigid materials and driven by propellers or jet thrusters, which consume a significant amount of power. Large power consumption necessitates a sizeable battery, which limits the ability to design a small robot. Propellers and jet thrusters generate considerable noise and vibration, which is counterproductive when studying acoustic signals or studying timid species. Bioinspired soft robots provide an approach for underwater exploration in which the robots are comprised of compliant materials that can better adapt to uncertain environments and take advantage of design elements that have been optimized in nature. In previous work, we demonstrated that frameless DEAs could use fluid electrodes to apply a voltage to the film and that effective locomotion in an eel-inspired robot could be achieved without the need for a rigid frame. However, the robot required an off-board power supply and a non-trivial control signal to achieve propulsion. To develop an untethered soft swimming robot powered by DEAs, we drew inspiration from the jellyfish and attached a ring of frameless DEAs to an inextensible layer to generate a unimorph structure that curves toward the passive side to generate power stroke, and efficiently recovers the original configuration as the robot coasts. This swimming strategy simplified the control system and allowed us to develop a soft robot capable of untethered swimming at an average speed of 3.2 mm/s and a cost of transport of 35. This work demonstrates the feasibility of using DEAs with fluid electrodes for low power, silent operation in underwater environments.

In this paper the authors present a method for the correlation of different datasets, captured during experimental tests performed according to ECE R21 on a cockpit module. The data were collected by specialized transducers by National Instruments data acquisition system interfaced by dedicated toolbox with MATLAB. The paper project presents the way of acquisition of data set and the test bench. According with ECE R21 it’s using a gravitational pendulum consisting of a spherical rigid impactor that is supported by roll bearings to a rigid frame. By this methodology one can check a specific data set and to define consistent performance parameters set. The results obtained will be correlated with each other, so we can identify the acceleration at a certain angular position. On the other hand, in the paper project is presented the process to calculate kinetic energy and the energetic coefficient of restitution. The methodology provides the background for future investigation in designing efficient countermeasures useful for vehicle interior trimmings. Obtaining a correlation of data set we can analyze more materials with numeric simulation and we can identify new materials to minimize costs and increase performance. The paper is focused of the experimental investigation and provides the support for developing testing and data analysis procedures in the field of impact related events. The type of the material is also important thus it has an important contribution in the quality of the simulation result.

This paper introduces a novel directional control method of self-propelled oil droplets. Oil droplets locomote spontaneously with surfactant action. This self-propulsion is caused by Marangoni convection within the oil droplet due to differences in the surfactant concentration at the droplet surface. Recent studies have reported that self-propelled oil droplets change their locomotion style depending on their shapes. We confirm that spherical oil droplets move randomly, including straight motion, bending motion, and rotation. In particular, we discover that boomerang-shaped oil droplets exhibit only straight motion. In this study, we introduce an exoskeleton for the directional and velocity control of oil droplets. A droplet shaped as a boomerang by an exoskeleton locomotes in the direction from a concave region to a convex region. Through experimental studies, we found that the stability of the velocity and locomotion direction depended on the boomerang shape. Self-propelled oil droplets with exoskeletons were then applied to a transporting robot driven only by the energy obtained from chemical reactions. We demonstrate the robot pushes and transports an object floating on water.

Thermal management is essential for living organisms and electronic devices to survive and maintain their own functions. However, developing flexible cooling devices for flexible electronics or biological systems is challenging because conventional coolers are bulky and require rigid batteries. In nature, skins help to maintain a constant body temperature by dissipating heat through perspiration. Inspired by nature, an artificial perspiration membrane that automatically regulates evaporation depending on temperature using the programmed deformation of thermoresponsive hydrogels is presented. The thermoresponsive hydrogel is patterned into pinwheel shapes and supported by a polymeric rigid frame with stable adhesion using copolymerization. Both shape of the valve and mechanical constraint of the frame allow six times larger evaporation area in the open state compared to the closed state, and the transition occurs at a fast rate (≈1 s). A stretchable membrane is selectively coated to prevent unintended evaporation through the hydrogel while allowing swelling or shrinking of the hydrogel by securing path of water. Consequently, a 30% reduction in evaporation is observed at lower temperature, resulting in regulation of the skin temperature at the thermal model of human skins. This simple, small, and flexible cooler will be useful for maintaining temperature of flexible devices.

To build a machine gun on a helicopter board sufficiently rigid frame of shooting stand is required. The construction of the frame ensures changing a shoot direction in the vertical and rotation in the horizontal plane. The frame is hinged and can be pivoted to the inside of a helicopter. The frame design requires dynamic analysis and appropriate laboratory tests. The paper presents calculated results of the systems response to the applied dynamic loads in comparison to the laboratory tests results.

This article is devoted to the study of transients in the proposed rope system elements in the installation equipment of super heavy-lift launch vehicles (SHLLV) on the example of a promising rocket “Yenisei” in the process of its transfer to a vertical position on the launch complex. The considered lifting system, which is based on the polyspast system (PS) and in which winches are used as lifting mechanisms, can be considered as an alternative to the hydraulic lifting system, which has proven itself in such complexes as “Energy”, “N1”. A numerical simulation of the transporter-erector unit (TEU) lifting process with the launch vehicle (LV) by the finite element method (FEM) with variable matrices was carried out for two calculated cases characterized by an abrupt change in the system parameters: the initial moment (corresponding to the PS highest loading) of the rocket lifting into a vertical position, and the moment (corresponding to the change in the load torque direction) acting on the TEU (with LV) during the verticalization process. According to the calculation results, the dependences of the PS forces for a wide range of winding ropes on the winch drums speed values, calculation of the TEU rigid frame total structural strength was carried out. It is concluded that it is necessary to introduce additional control devices in the lifting mechanisms to maintain the ropes in a tight condition throughout the verticalization process. The research results can be useful in the designing the actuators for lifting mechanisms of the rope system.

With the aim of further understanding the seismic performance of extradosed cable-stayed bridges, this paper presents an experimental investigation of a three-pylon rigid-frame extradosed cable-stayed bridge by conducting 1/20 scaled longitudinal shake tables model tests at the laboratory of Tongji University, Shanghai, China. The design, construction and testing protocol of the test model are firstly introduced. Observation of the seismic damage situation and empirical data on the seismic responses of the test model are then provided. The test results show that: (1) severe seismic damage appeared at the bottom and upper parts of piers and damage at the bottom parts were much heavier; (2) no damage was observed on short pylons; (3) structural stiffness degradation occurred when PGA≥0.4g; (4) the vibration of the short pylon almost has no contribution in the displacement at the pylon top.

Arslan, Mehmet Emin/0000-0002-7582-638X WOS: 000466999500078 The main purpose of this study is to examine the behavior of the brick masonry and infill walls under cyclic horizontal loads, irrespective of reinforced concrete frames. For this purpose, the test walls, which are produced as non-plastered (plane), two side plastered and two side plastered and strengthened with zinc coated steel wire mesh by using vertical and horizontal hollow brick walls were tested in a rigid hinged steel loading frame under lateral cyclic loading. The findings were evaluated in terms of load carrying capacity, ductility and energy dissipation capacities. The tests carried out showed that the expected increases were provided any type of plastered walls in terms of stiffness with respect to the reference non-plastered walls. Besides this, wired mesh used in plastered walls increased significantly the ductility and consequently the energy dissipation capacity of the walls by maintaining wall integrity in an advanced stage of the loading. Also, both hollow brick and vertical brick infill walls strengthening with wired mesh increase load carrying capacity of the wall test specimens. Load carrying and energy dissipation capacities of wire meshed specimens almost five times more than those of plane test walls. (C) 2019 Elsevier Ltd. All rights reserved.

A fully integral bridge that is restrained at both ends by the abutments has been proposed to form a monolithic rigid frame structure. Thus, the feasible horizontal force effect due to an earthquake or vehicle braking is mainly prevented by the end-restraining abutments. In a recent study, a fully integral bridge with appropriate end-restraining abutment stiffness was derived for a multispan continuous railroad bridge based on linear elastic behavior. Therefore, this study aims to investigate the nonlinear behavior and seismic capacity of the fully integral bridge and then to assess the appropriate stiffness of the end-restraining abutment to sufficiently resist design earthquake loadings through a rigorous parametric study. The finite element modeling and analyses are performed using OpenSees. In order to obtain the force-deflection curves of the models, nonlinear static pushover analysis is performed. It is confirmed that the fully integral bridge prototype in the study meets the seismic performance criteria specified by Caltrans. The nonlinear static pushover analysis results reveal that, due to the end-restraining effect of the abutment, the lateral displacement of the fully integral bridge is reduced, and the intermediate piers sustain less lateral force and displacement. Then, the sectional member forces are well controlled in the intermediate piers by a proper application of the end-restraining abutments.

CNC machine tools are currently predominating in the machine-building industry. Generally, these machine tools are equipped with control systems supplied by the world's leading manufacturers, such as Siemens, Fanuc or HeidenHein, and are very expensive. In parallel, many cheap amateur and semi-professional CNC machine tool solutions are being developed. Below, a CNC milling machine of welded construction is described, which is intended to be, at the same time, a test stand. The design of the milling machine is based on steel closed sections of a large cross-section and a big wall thickness. This has allowed a rigid frame structure to be obtained. To obtain high displacement accuracy, high-accuracy profiled rail slideways have been used, along which pre-stressed linear ball bearings move. The machine tool has been furnished with a fourth numerically controlled axis, which is demountable.