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One of the most important problems is the stripping of the rope, which is a part of the drum-rope mechanisms required in the weight lifting operations used in today's crane systems, from the drum rope clamps under load. This article is a new study in the literature. In this study, the focus is on investigating the design and process parameters of the drum rope clamps used on the drum mechanisms in overhead cranes, simplifying and improving the production. In order to fulfil this objective, firstly, a prototype table-top experimental system that constructs a drum-rope connection has been established. In the experimental study, flat and radius clamps were used as design parameters and the squeezing forces of the bolts connecting the clamps to the drum were considered as process parameters. The tensile force to be applied throughout the study was obtained by making various mathematical calculations. Finally, it was concluded that design and process parameters have significant effects on crane drum-rope systems and comparisons were made on drum rope clamp designs. In addition, it is seen from the experimental results that it has an impact on cost and operational efficiency. [ABSTRACT FROM AUTHOR]

This study presents an improved maximum boost control (MBC) method for three-level impedance source inverter. This technique offers removal of sixth frequency component from the inductor current present in the existing MBC technique of ZSI (Impedance Source Inverter). In addition, the proposed technique reduces the common mode voltage to 1/6th of dc bus voltage. The conventional zero vectors of three-level switching diagram are suitably modified and implemented for the case of 3L-CDBCZSI (three level controlled diode bridge clamped based impedance source inverter). It offers increased switching frequency of impedance network and reduces the size of passive components. On the basis of the proposed technique, the merits offered by 3L-CDBCZSI are highlighted and compared with T-type and diode clamped based ZSI. Simulation and experimental results are presented to verify the correctness of the proposed method. [ABSTRACT FROM AUTHOR]

• A semi-analytical method is adopted for arbitrary fluid-conveying spatial pipeline. • The actual flexible-bracket clamp stiffness is considered. • Virtual springs are used for the straight-curved connection. In-depth research is imperative for complex spatial pipelines with fluid-structure interaction. A comprehensive and universal three-dimensional semi-analytical modeling method is first established for complex fluid-conveying spatial pipelines under the base excitation with arbitrary connections and configurations under different boundary conditions. The virtual spring technology is used to connect the straight and curved pipeline segments with spatial angles and simulate boundary conditions. For a thorough analysis, the actual stiffness of the bracket-clamp system is experimentally measured for the first time. The multi-level coupling dynamic model of part, component, and system levels under actual boundary conditions is established. An efficient method for solving the fluid-structure coupling pipeline system dynamics considering the base excitation is proposed based on energy method. The mid-plane displacement function of the Fourier series is introduced and solved using the principle of modal superposition. Hammer impact modal experiments, ANSYS software and vibration response experiments are performed on spatial pipelines supported by flexible bracket-clamps; the numerical and experimental results support the semi-analytical results. The degenerate model is verified with the simple plane pipelines in other references, and the errors are less than 5 %. The proposed method exhibits broad applicability and generalizability, making it suitable for various configurations and boundary conditions. [ABSTRACT FROM AUTHOR]

Summary: The four‐level hybrid clamp converter (4L‐HCC) is one of the next‐generation multilevel topologies due to its simplified structure and excellent performance. However, it consists of several DC‐link and flying capacitors, which must be precharged to the rated voltage before the normal operation. Without proper control, those internal capacitors could easily induce inrush currents and cause system fatal failure due to the unsymmetrical circuit structure. This paper proposes soft start‐up control methods for both single‐phase and three‐phase HCCs. The precharging mathematical models of DC‐link and flying capacitors are established. A straightforward algorithm using the selected switching states and rotating regions is developed to build precharging circuits properly. A full‐scale simulation model and a downscale laboratory prototype of the 4L‐HCC are established to validate the superiority of the proposed method. Results demonstrate that the proposed approach is effective in charging all capacitors through internal elements rapidly with suppressed and controllable charging currents. [ABSTRACT FROM AUTHOR]

Microgrippers offer better operational flexibility in biological micromanipulation. However, they face challenges in size miniaturization and environmental adaptability (especially in biological liquid environments). To overcome these challenges, a novel pneumatic microgripper is proposed with a thin-walled multi-airbag structure that directly drives the clamping jaws in motion, with a simple and compact overall construction. The microgripper has a maximum clamping range of 925 μm and can provide a clamping force exceeding 25 mN, capable of lifting loads over 300 times its weight. The microgripper is integrative and can be mass-produced with biocompatible resins in a single-step high-precision 3D printing process. The pneumatic microgripper is utilized to achieve the sorting and assisted injection of mouse oocytes (60–80 μm), assisted cutting of porcine oocytes (100–120 μm), and microscopic threading (10–15 μm) operation with two-finger cooperation. These demonstrations confirm it can operate fine manipulation of microscopic biological structures in air and liquid, and has good biocompatibility and cooperative operational ability. The developed pneumatic microgripper shows broad application prospects in biomedical applications such as microsurgery, micro biopsy, and assisted reproduction. [Display omitted] • A structurally integrated pneumatic microgripper is proposed for fine biological micromanipulation. • Micromanipulations of tiny biological structures are performed in air and liquid. • Innovative structural design enables a small structure while combining a large clamping range and high clamping force. • The microgripper is fabricated in a single-step high-precision 3D printing process. [ABSTRACT FROM AUTHOR]

The classical model predictive control (MPC) usually aims to minimize the current error at the end of the control period. This method is equivalent to minimizing the current total harmonic distortion (THD) when the control period tends to be infinitely small. However, due to the limitations of hardware in practice, the optimization effect of current THD is not obvious. Aiming at the above problem, an improved double-vector model predictive control method is proposed for the single-phase active-neutral-point-clamped five-level (ANPC-5L) inverter. Two voltage vectors in each control cycle are used in this method to reduce the current THD by minimizing the area enclosed by the actual and reference current. In addition, a capacitor voltage control method is designed for the problem of multiple control objectives coupling in this structure. In this method, an idea of hierarchy is designed for voltage jump and switching transition limits, neutral point (NP) voltage, and flying capacitor (FC) voltage, achieving the effect of weightless factor and good dynamic and static performance. Finally, the effectiveness of the proposed method is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

Off-clamp partial nephrectomy represents one of the latest developments in nephron-sparing surgery, with the goal of preserving renal function and reducing ischemia time. The aim of this study was to evaluate and compare the functional, oncologic, and perioperative outcomes between off-clamp robot-assisted partial nephrectomy (off-C RAPN) and off-clamp open partial nephrectomy (off-C OPN) through a propensity score-matched (PSM) analysis. A 1:1 PSM analysis was used to balance variables potentially affecting postoperative outcomes. To report surgical quality, 1 year trifecta was used. Univariable Cox regression analysis was performed to identify predictors of trifecta achievement. The Kaplan–Meier method was used to compare cancer-specific survival (CSS), overall survival (OS), disease-free survival (DFS), and metastasis-free survival (MFS) probabilities between groups. Overall, 542 patients were included. After PSM analysis, two homogeneous cohorts of 147 patients were obtained. The off-C RAPN cohort experienced shorter length of stay (LoS) (3.4 days vs. 5.4 days; p < 0.001), increased likelihoods of achieving 1 year trifecta (89.8% vs. 80.3%; p = 0.03), lower postoperative Clavien–Dindo ≤ 2 complications (1.3% vs. 18.3%, p < 0.001), and lower postoperative transfusion rates (3.4% vs. 12.2%, p = 0.008). At univariable analysis, the surgical approach (off-C RAPN vs. off-C OPN, OR 2.22, 95% CI 1.09–4.46, p = 0.02) was the only predictor of 1 year trifecta achievement. At Kaplan–Meier analysis, no differences were observed between the two groups in terms of OS (log-rank p = 0.451), CSS (log-rank p = 0.476), DFS (log-rank p = 0.678), and MFS (log-rank p = 0.226). Comparing RAPN and OPN in a purely off-clamp scenario, the minimally invasive approach proved to be a feasible and safe surgical approach, with a significantly lower LoS and minor rate of postoperative complications and transfusions as a result of improved surgical quality expressed by higher 1 year trifecta achievement. [ABSTRACT FROM AUTHOR]

Clamping precision as a key factor of precision injection molding of high-quality plastic parts is restricted by low-precision clamping systems. Herein, a novel clamping method capable of sensing mold misalignment and self-adjusting mold position and attitude through floating structures is proposed to eliminate the restriction of clamping system, thereby achieving high clamping precision. The innovative clamping method possesses prestress steel wire-winding frames and rubber capsules filled with hydraulic oil, which ensures the floating structures work. Meanwhile, the hydraulic oil provides isostatic pressure to clamp the mold. The working space of the floating structures and the loading of the prestress steel wire-winding frames have been modeled to confirm their feasibility in the self-adaptive clamping method. Based on the modeling activities, a prototype injection molding machine was developed to evaluate the clamping precision. The experimental results indicate that the parallelism between the mold plates is 0.031 mm, far superior to that in China Machinery Industry Standards, and the uneven clamping force rate on mold cavity surface is 1.3 %. Moreover, the clamping force repeatability is only 0.14 %, superior to toggle and two-platen clamping systems. This method offers a new chance for the development of precision injection molding. • A novel clamping method capable of sensing mold misalignment and self-adjusting mold position and attitude. • The clamping method utilizes capsule with hydraulic oil to provide isostatic pressure and ensure floating structures work. • The prestress steel wire-winding frames in the clamping system cannot restrict degree of freedom of floating structures. • The developed clamping system is verified that the clamping precision is superior to traditional clamping systems. [ABSTRACT FROM AUTHOR]

Consideration of an eccentric load introduction in the buckling check acc. to the reduced stress method in EN 1993‐1‐5 – part 2: numerical studies Part 1 of this article describes the large‐scale buckling tests under biaxial loading carried out at the Technical University of Munich in the course of projects, as well as their recalculation and modeling using the finite element method. The numerical model described in part 1 was extended and slightly adapted for the following parameter study. The flange is taken into account in the modeling so that the clamping effect of the freely rotating flange is included. Without the connection of a bottom plate or flange, no eccentric load can be introduced into the web, so some clamping effect is essential and therefore the assumption of Navier's support at the edge of the eccentric load introduction does not apply. The results of the numerical parameter study with the model are briefly summarized in this part 2. These are then compared and evaluated with the reduced stresses method acc. to DIN EN 1993‐1‐5:2019. The comparison shows that an enormous economic potential for the buckling analysis can already be achieved by considering a freely rotating flange for I‐sections. Therefore, an approach is developed and presented that allows the consideration of an eccentric load introduction in the buckling analysis and at the same time conservatively accounts for the clamping effects that occur. [ABSTRACT FROM AUTHOR]

Soft actuators capable of remote-controlled guidance and manipulation within complex constrained spaces hold great promise in various fields, especially in medical fields such as minimally invasive surgery. However, most current magnetic drive soft actuators only have the functions of position control and guidance, and it is still challenging to achieve more flexible operations on different targets within constrained spaces. Herein, we propose a multifunctional flexible magnetic drive gripper that can be steered within complex constrained spaces and operate on targets of various shapes. On the one hand, changing the internal pressure of the magnetic gripper can achieve functions such as suction or injection of liquid and transportation of targets with smooth surfaces. On the other hand, with the help of slit structures in the constrained environment, by simply changing the position and orientation of the permanent magnet in the external environment, the magnetic gripper can be controlled to clamp and release targets of linear, flaked, and polyhedral shapes. The full flexibility and multifunctionality of the magnetic gripper suggest new possibilities for precise remote control and object transportation in constrained spaces, so it could serve as a direct contact operation tool for hazardous drugs in enclosed spaces or a surgical tool in human body cavities. [ABSTRACT FROM AUTHOR]

Although strain engineering and soft-clamping techniques for attaining high Q-factors in nanoresonators have received much attention, their impact on nonlinear dynamics is not fully understood. In this study, we show that nonlinearity of high-Q Si3N4 nanomechanical string resonators can be substantially tuned by support design. Through careful engineering of support geometries, we control both stress and mechanical nonlinearities, effectively tuning nonlinear stiffness of two orders of magnitude. Our approach also allows control over the sign of the Duffing constant resulting in nonlinear softening of the mechanical mode that conventionally exhibits hardening behavior. We elucidate the influence of support design on the magnitude and trend of the nonlinearity using both analytical and finite element-based reduced-order models that validate our experimental findings. Our work provides evidence of the role of soft-clamping on the nonlinear dynamic response of nanoresonators, offering an alternative pathway for nullifying or enhancing nonlinearity in a reproducible and passive manner. In the design optimization of resonance frequencies and Q-factor of nanomechanical resonators, the influence of geometric design on the nonlinear dynamics has been rarely investigated. Here, the authors tune the stress field via soft-clamping, simultaneously increasing both the Q-factor and the onset of nonlinearity of a Si3N4 string resonator. [ABSTRACT FROM AUTHOR]

An investigation is performed in this paper to analyze the nonlinear thermo-electro-mechanical response of long sandwich cylindrical shells with functionally graded porous (FGP) core and thin piezoelectric actuator layers. The FGP core of the sandwich shell is assumed to be temperature- and microstructure-dependent. It is assumed that the sandwich shell is subjected to uniform lateral pressure loading in a thermo-electrical environment. The equilibrium equations of the shell with infinite length are established with the aid of the virtual displacement principle and von Kármán kinematic assumptions. The governing equations are obtained in terms of displacement components based on the first-order shear deformation model of shallow cylindrical shells and the modified couple stress theory. These nonlinear differential equations are analytically solved for a sandwich shell having both the simply-supported and clamped–clamped edge conditions by employing a two-step perturbation technique. Analytical closed-form solutions are determined as a relationship including the load parameter and the mid-span deflection. The comparison examples are made with the existing results in the literature for a simple functionally graded shell, where good agreement is obtained. It is shown that the nonlinear response of the sandwich shell is highly dependent upon the temperature variation, power law index, porosity coefficient, couple stress parameter, piezoelectric layers, and geometrical parameters of the shell. [ABSTRACT FROM AUTHOR]

In this paper, a new high step-up converter with a simple structure is presented. The auxiliary circuit of the proposed converter is in the form of active clamp, which provides soft switching condition under zero voltage for the main and auxiliary switches, hence the converter has high efficiency. Since the auxiliary switch added in the converter works as an active clamp and has a complementary command with the main switch, the proposed converter is not complicated in terms of the control circuit and does not need to design a new control circuit. This converter has a high voltage gain that provides a high output voltage with a lower duty cycle, so it is suitable for a new energy production system such as a solar system. The proposed converter has been fully analyzed and in order to prove the theoretical analysis, an experimental prototype has been implemented and tested at a power of 500 W, which in this power an efficiency of about 97.3% has been obtained. [ABSTRACT FROM AUTHOR]

There is accelerating demand for energy-absorbing structures fabricated from lightweight materials with idealized, near-constant force responses to simultaneously resolve the engineering challenges of vehicle mass reduction and improved occupant safety. A novel compounded energy dissipation system composed of AA6061-T6 and AA6061-T4 tubing subjected to hybrid cutting/clamping and H130, H200 and H250 PVC foam compression was investigated utilizing quasi-static experiments, finite element simulations and theoretical modeling. Identical structures were also subjected to axial crushing to compare with the current state of the art. The novel cutting/foam crushing system exhibited highly stable collapse mechanisms that were uniquely insensitive to the tube/foam material configuration, despite the disparate material properties, and exceeded the energy-absorbing capacity and compressive force efficiency of the axial crushing mode by 14% and 44%, respectively. The simulated deformation profiles and force responses were consistent with the experiments and were predicted with an average error of 12.4%. The validated analytical models identified numerous geometric/material configurations with superior performance for the compounded AA6061/PVC foam cutting/foam crushing system compared to axial crushing. An Ashby plot comparing the newly obtained results to several findings from the open literature highlighted the potential for the compounded cutting/foam crushing system to significantly outperform several alternative lightweight safety systems. [ABSTRACT FROM AUTHOR]

Magnetoelectric thin-film cantilevers consisting of strain-coupled magnetostrictive and piezoelectric layers are promising candidates for magnetic field measurements in biomedical applications. In this study, we investigate magnetoelectric cantilevers that are electrically excited and operated in a special mechanical mode with resonance frequencies above 500 kHz. In this particular mode, the cantilever bends in the short axis, forming a distinctive U-shape and exhibiting high-quality factors and a promising limit of detection of 70 p T / Hz 1/2 at 10 Hz. Despite this U mode, the sensors show a superimposed mechanical oscillation along the long axis. The induced local mechanical strain in the magnetostrictive layer results in magnetic domain activity. Due to this, the mechanical oscillation may cause additional magnetic noise, deteriorating the limit of detection of such sensors. We compare finite element method simulations with measurements of magnetoelectric cantilevers in order to understand the presence of oscillations. From this, we identify strategies for eliminating the external effects that affect sensor operation. Furthermore, we investigate the influence of different design parameters, in particular the cantilever length, material parameters and the type of clamping, on the amplitude of the undesired superimposed oscillations. We propose design guidelines to minimize the unwanted oscillations. [ABSTRACT FROM AUTHOR]

Current automotive brake systems (pneumatic/hydraulic) are based on a split design: a central unit providing pressure and brake calipers transforming this pressure into clamping forces. Existing electromechanical brake calipers work without a central unit; but despite their simplicity they are not yet used. One major reason is the need of high forces and high electrical power for loading brake pads and calipers during braking. A possible solution is the application of a statically balanced spring mechanism; it stores elastic energy in a preloaded reversible spring mechanism integrated in the caliper. Using a nonlinear linkage mechanism, the stored energy transfers back and forth to and from the elastic parts of the brake caliper. Consequently, the additional power needed for applying and releasing the brake reduces significantly. The article analyzes the basic feasibility of such an actuator based on a double slider crank mechanism, which is determined for an application in a typical automotive disk brake caliper with high clamping forces of 20 kN. Experimental results from a demonstrator under real friction and stiffness conditions are presented and analyzed based on a theoretical model. The results prove the benefits of reducing driving power and also reveal critical points of the design. [ABSTRACT FROM AUTHOR]

In this study, a resonant single-wing bionic piezoelectric motor based on a biasing self-clamping mechanism inspired by dragonfly flight was designed, assembled, and tested. The main mechanism of the designed piezoelectric motor includes a mover (including a vibrator, clamping foot, bionic pedestal, etc.), a stator, and other auxiliary components. The clamping foot of the mover contacts the side of the stator to form a biasing self-clamping mechanism, which can achieve a clamping effect within half a cycle of the vibrator's resonant vibration. The piezoelectric plate on the vibrator receives a single harmonic excitation from the signal generator, causing the base plate to bend and distort. The base plate drives the clamping foot to move regularly, causing the mover to perform a linear motion. Moreover, repeated single harmonic excitations can realize the continuous movement of the mover. The structure of the piezoelectric motor was optimized using COMSOL6.0, which is a finite element analysis software. The first-order bending vibration of the vibrator was chosen as the working mode through finite element simulation, and an experimental platform was built. The performance of the prototype piezoelectric motor was tested and verified on the experimental platform. The final experimental data show that under the conditions of 300 Vp–p excitation voltage and 109 Hz driving frequency, the maximum no-load speed of the prototype reaches 6.184 mm/s, and the maximum load of the motor is 4 g. [ABSTRACT FROM AUTHOR]

A new three‐phase two‐switch voltage clamping buck Power Factor Correction (PFC) is presents in this paper. The principle and equations of operations are described in detail. Based on the volt‐second balance principle of input inductance in the new converter, this paper gives the design method of the circuit's key components, with voltage and current stresses analyzed. On the basis of the theory above, a prototype with parameters of a 5 kW is designed. Problems of extremely high switch peak voltage stress in the conventional one are solved. The manufacturing cost of high power three phase rectifier has been significantly decreased. A 5 kW experimental prototype with unity power factor, 4.4% input line current THD, 200 Vdc output, and system efficiency of 96% at full load under 380 Vrms input line‐to‐line voltage has been successfully implemented. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Due to the widespread use of static power converters in various industries and sensitive applications such as ground power units (GPUs), it is essential that the inverters have high reliability. A failure in the inverters can cause undesirable consequences such as low performance, shutting down the system, and losing the stability of the entire system. On the other hand, in some critical industrial processes with high standstill costs and safety‐aspect concerns, such as aircraft, high reliability, and survivability of the system, are very important. Therefore, the use of fault‐tolerant (FT) inverters is inevitable in such applications. In this paper, using a three‐level fault‐tolerant neutral point clamped (FT‐NPC) inverter, the reliability of the GPUs is increased and it results in higher availability and continuous system performance. Furthermore, a simple automatic fault detection (FD) algorithm is presented by taking the inverter pole voltage as a FD parameter. The inverter is analyzed for open‐circuit fault in the switches, and the reliability of the FT‐NPC inverter is compared with the classic inverter. The simulation and experimental results of the 2‐kVA converter prototype are presented to confirm the FT inverter performance and the proposed method. [ABSTRACT FROM AUTHOR]

A glass fiber reinforced elastomer (FRE) sheet is used to design a simple clamping mechanism for prospective engineering applications. The mechanism is based on the phenomena of snap‐through buckling of a segment of a shallow cylindrical shell. It is simply supported at the straight edges and actuated by edge moments. The main objective of such a mechanism is the resulting clamping force, being related to the response of the material under bending. Bending includes compressive stresses, and since the fibers are embedded in a very soft matrix, it is important to understand their contribution to the compressive stiffness of the FRE sheet. For this purpose, numerical simulations by means of the Finite Element Method are performed and a simulation strategy for predicting the clamping force of the mechanism is presented. The clamping forces predicted for FRE composites with and without the contribution of fibers to the compressive stiffness are compared to that of the pure elastomer. The results illustrate the potential of FRE based structures in mechanism‐like applications. If an adequate clamping force is desired, the pure elastomer is not suitable for being used in this kind of clamping mechanism and the fiber reinforcement is necessary. If the fibers contribute to the compressive stiffness, a significantly higher clamping force is predicted. Furthermore, the FRE based structure shows a complex snap‐through deformation pattern, which has to be taken into account in the design of the mechanism and which requires non‐trivial simulation strategies. [ABSTRACT FROM AUTHOR]

In this article, the problem of the free vibration behavior of a cantilever Euler-Bernoulli beam with various non-classical boundary conditions, such as rotational, translational spring, and attached mass is investigated. For describing the differential equation of the system. An analytical procedure is proposed firstly, and a numerical method based on the differential transform method DTM is developed in order to validate the obtained results. A parametric study for various degenerate cases is presented with the aim to analyze the influence of rotational stiffness, vertical stiffness, and mass ratio on the free vibration response of the beam, particularly on its modal characteristics. The results show that the non-classical boundary conditions significantly affect the natural frequency and mode shapes of the studied beam system in comparison to the case of a classical boundary conditions such as Simply supported, clamped-clamped, etc. The comparison between the obtained results based on the proposed analytical solution and numerical scheme, and those available in the literature shows an excellent agreement. [ABSTRACT FROM AUTHOR]

Background: Metal lattice structures obtained through Selective Laser Melting may increase the strength-to-weight ratio of advanced 3D printed parts, as well as their damping properties. Recent experimental results showed that AlSi10Mg and AISI 316L lattices are characterized by higher Rayleigh damping coefficients with respect to the fully dense material. However, some unclear or contradictory results were found, depending on the experimental setup adopted for modal analysis. Objective: In this work the influence of the experimental setup when performing modal analysis on different SLM AISI 316L lattice structures was deeply investigated. The study provides a critical comparison of various experimental modal analysis approaches, allowing to evaluate the influence of external damping sources and material internal damping phenomena. Methods: The dynamic behaviour of SLM AISI 316L specimens incorporating lattice structures was estimated by means of pulse testing and sinusoidal excitation through an electromagnetic shaker. The validity of the viscous damping model was assessed by means of sinusoidal excitation with different levels of vibration velocity. Moreover, the influence of experimental setup on modal analysis results was critically evaluated, by considering different actuators, contact and non-contact sensors and boundary/clamping conditions. Results: The classical viscous damping model describes with good approximation the damping properties of SLM lattice structures. When exciting single specimens in free-free conditions, those embedding lattice structure and unmelted metal powder filler were characterized by superior internal damping properties with respect to the specimens incorporating the lattice structure without any filler, which was however more effective than the full density equivalent material. Most of the other experimental setups introduced additional external damping sources, that could alter this important outcome. Conclusions: SLM lattice structures embedded into 3D printed components provide superior damping properties against mechanical and acoustic vibrations and the metal powder filler does significantly enhance such damping capacity. A correct estimation of material internal damping was achieved by applying non-contact sensors and free-free boundary conditions, whereas other experimental setups were partly inadequate. [ABSTRACT FROM AUTHOR]

Recently, integrated gate-commutated thyristors (IGCTs) have shown a great potential for the soft-switching dc transformer applications based on LLC resonant converter. The zero-voltage switching that is present in this converter topology enables an operation of IGCTs without clamping circuit and with significantly higher switching frequencies, while maintaining the exceptionally low conduction losses. The high voltage and current ratings of the IGCTs make them a preferred choice for an efficient bulk power transmission. This article shows how gate units for IGCTs can be optimized for this soft-switching application. It presents a simplification of the driving topology and the design process for high switching frequencies. This results in low power consumption and a very small size of the gate unit. The prototype of the gate unit is built and experimentally validated in a 2.5 kV 0.75 kA resonant operation of the IGCT. [ABSTRACT FROM AUTHOR]

In this study, we propose a bidirectional high-speed inchworm actuator driven by two PZT stacks by employing innovative flexible symmetric clamp feet with a multilayer structure design, where the switching of the clamp feet is performed by a single PZT. In addition, the symmetric clamp foot design synchronizes the clamping forces and improves the efficiency of the driving mechanism. The drive principle is analyzed, and a model on the clamping performance with respect to the single-step length is developed based on the compliance matrix method. A numerical analysis is conducted to verify the proposed model and optimize driving performance. The experimental results demonstrate that the proposed actuator achieves high-speed and stable bidirectional motion with a maximum speed of 43.8 mm/s and a maximum driving force of 3 N at a driving frequency of 150 Hz, which significantly outperforms existing results. The experiments also demonstrate that the motion resolution of the proposed actuator is 1.57 nm with a large travel range (25 mm in this particular design). The innovative design of the PZT inchworm actuator promises various applications in precision engineering with high-speed and large range nanomanipulatons. [ABSTRACT FROM AUTHOR]

This article evaluates the model‐free predictive current control for three‐level inverter‐fed permanent magnet synchronous motor drives based on a full‐update technique of dq‐axes current variations. The proposed method is implemented in three steps. First, the defined feature current variations are calculated relying on the projection relationship between the corresponding voltage vectors and are assigned to obtain the other current variations of the same category to enhance the updating frequency of dq‐axes current variations and the current quality as well. Second, a voltage pre‐selection is conducted in the predictive current control by virtue of the applied voltage vector. In this case, the enumeration of all available vectors is effectively omitted, yielding the reduced computational burden. At last, the unbalanced neutral‐point voltage of three‐level inverter is eliminated to improve the control performance. Experimental and simulated results have been employed to highlight the favorable performance of the proposed control strategy. [ABSTRACT FROM AUTHOR]

The requirements of large thrust in bidirectional motion, high specific power (power/weight ratio), reliable self-locking at power off state, and compact size envelope for various applications of existing piezoelectric actuators are still urgent. To address these challenges, this study makes full use of the piezoelectric material's excellent dynamic performance, robust force output, and high energy density to propose a novel inchworm piezoelectric actuator, which relies on the alternate clamping of two nuts independently rotated by two ultrasonic motors on a feed-screw in accordance with a piezoelectric stack (piezo-stack) excitation to accumulate the piezo-stack's electric field-induced strain periodically and realize power output. The operation principle and design process of the presented actuator were elaborated, and a prototype was fabricated and experimented. Results indicate that the actuator has achieved an expected bidirectional motion for powering the tensile load and compressive load, attained a micrometer-sized step resolution, produced a 3.08 mm/s free speed, a 700 N stall load, and a 1.34 W/kg specific power, and shown a favorable prospect for further development. [ABSTRACT FROM AUTHOR]

Soft nonlinear support is a major engineering project, but there are few relevant studies. In this paper, a dynamic pipeline model with soft nonlinear supports at both ends is established. By considering the influence of the Coriolis force and centrifugal force, the dynamical coupling equation of fluid-structure interaction is derived with extended Hamilton's principle. Then, the approximate analytical solutions are sought via the harmonic balance method. The amplitude-frequency response curves show that different effects can be determined by approximate analysis. It is demonstrated that the increase in the fluid velocity can increase the amplitude of the pipeline system. The frequency range of unstable response increases when the fluid pressure raises. The combination of the soft nonlinear clamp and the large geometrical deformation of the pipeline affects the nonlinear vibration characteristic of the system, and the external excitation force and damping have significant effects on the stability. [ABSTRACT FROM AUTHOR]

The clamping mechanism plays an important role in obtaining high-quality products of the injection molding process. The clamping mechanism of the five-point double-toggle has been widely used for the high-speed plastics injection molding machine. The purpose of this paper is to optimize the five-point double-toggle clamping mechanism through multi-body dynamics analysis. This work also provides guidelines and a clear understanding for designing the clamping system in an injection molding machine with various clamping forces. The theoretical calculation has been handled first and then the computational model has been verified in this study. In addition, the effects of clamping forces on the main dimensions, including movable-fixed plate thickness, tie-bar diameter, and average link cross-section have been investigated theoretically and numerically. The results show that the optimal design allows reaching a high force amplified ratio and that the obtained mechanism has good kinematic performance and works steadily with lower energy consumption and lower cost than the preliminary design. Moreover, the relationships between the parameters such as the critical angles of the double-toggle clamping mechanism, the ratio of force amplification, and the stroke of movable mold have been found in this work. The optimized parameters will yield useful knowledge to design and manufacture the clamping mechanism of the microinjection molding machine in practice. [ABSTRACT FROM AUTHOR]

A new multimodal bidirectional linear inertial impact motor with bidirectional motion based on self-clamping control driven by a single-harmonic signal was designed and manufactured. By applying driving signals of different resonant frequencies to the piezoelectric plate of a piezoelectric motor combined with the unique structural design of the motor, the piezoelectric motor has multiple modes and has the ability of two-way movement. First, the overall structure of the motor is introduced, and its working principle and theoretical displacement characteristics are presented through the periodic motion diagram of the piezoelectric motor. Second, the simulation analysis is carried out to determine the working modal of the proposed motor with COMSOL5.2. Finally, a motor prototype is developed, and the accuracy of the working principle and the simulation analysis is verified through experimental tests. When the motor has no load, the driving voltage is 200 Vp–p. The maximum speed when moving to the right reached 3.125 mm/s when the preload is 2 N, and the driving frequency is 96 Hz. The maximum speed when moving to the left reached 4.301 mm/s when the preload is 4 N, and the driving frequency is 148 Hz. In the load capacity test of the motor prototype, the maximum load of the piezoelectric motor prototype moving to the right and left can reach 0.4 and 0.6 N, respectively. Compared with similar inertial impact motors, the proposed motor achieves flexible control of driving and switching of two-way movement conveniently and has a certain driving ability. [ABSTRACT FROM AUTHOR]

Flexible Roll Forming (FRF) allows the forming of components with a variable cross section along the length of the component. However, the process has only limited application in the automotive industry due to wrinkling in the flange which currently prevents the forming of high strength steels and limits the part shape complexity. This paper presents a new forming technology, Incremental Shape Rolling (ISR), where a pre-cut blank is clamped between two dies, and then a single forming roll is used to incrementally form the material to the desired shape. The new process is similar to some Incremental Sheet Forming (ISF) approaches but with the difference that Incremental Shape Rolling (ISR) allows the manufacture of longitudinal components from high strength metal sheets. In this work, a numerical model of the ISR of a straight section is developed. Experimental prototyping trials are performed and are used to validate the numerical model which is then applied to analyse the new forming process. The results show that in ISR, tensile residual strains are developed in the flange. Flange wrinkling is observed and directly linked to the number of forming passes that are used in the process. [ABSTRACT FROM AUTHOR]

The paper presents tribological tests of selected materials used as liners in a composite hydraulic cylinder. Three coating materials were used for the analysis: Sika F180 polyurethane, Huntsman Araldite LY1564 with Aradur 3487 amine hardener and Bezlona 1111 Super Metal. In addition, uncoated carbon epoxy laminate (CFRP) samples were used as reference material. The instantaneous course of the friction force, its maximum and average value, were the analysed parameters. Ball-on-disk tests were performed on a specialised tester that allows, among other things, to control the operating conditions (clamping force, operating temperature, speed, friction path) and measurement of the instantaneous value of the friction force. After these tests, the friction paths were observed using a Leica DCM8 contactless profilometer with an EPI 20x lens. The amount of energy dissipated due to friction was also determined. The conducted tests and comparative analyses allowed to conclude that the F180 material is the most desirable in terms of tribological properties. [ABSTRACT FROM AUTHOR]

This paper deals with the modelling and stabilization of a flexible clamped beam controlled with a piezoelectric actuator in the self-sensing configuration. We derive the model starting from general principles, using the general laws of piezoelectricity. The obtained model is composed by a PDE, describing the flexible deformations dynamics, interconnected with an ODE describing the electric charge dynamics. Firstly, we show that the derived linear model is well-posed and the origin is globally asymptotically stable when a voltage control law, containing the terms estimated in the self-sensing configuration, is applied. Secondly, we make the more realistic assumption of the presence of hysteresis in the electrical domain. Applying a passive control law, we show the well-posedness and the origin’s global asymptotic stability of the nonlinear closed-loop system. [ABSTRACT FROM AUTHOR]

Aiming at the technical requirements of pipeline repair with serious damage, such as small holes and cracks, the design of enhanced pipeline repair clamp is carried out. The different structure forms of enhanced structure are analyzed, and the enhanced structure used in the design is determined. Aiming at the reinforcement structure of pipeline repair clamp, the enhanced theory research is carried out, and the theoretical formula of the relationship between the axial reinforcement force and the bolt pre-tightening force is obtained. The finite element simulation of typical angle tooth shape is carried out by using the finite element software, and the corresponding stress of tooth top is obtained. Considering the influence of friction coefficient, the stress of isosceles triangle and non-isosceles triangle are analyzed. The results show that the stress of isosceles triangle tooth is better than that of non-isosceles triangle tooth, 90° isosceles triangle tooth angle and the isosceles triangle tooth with friction coefficient of 0.8 between slip and pipe can be used to design slip when processing conditions permit. The above work can provide a reference for the enhanced structure design of pipeline repair clamp. [ABSTRACT FROM AUTHOR]

Analysis of nonlinear response of thick FGM beams subjected to either thermal or mechanical load is performed. Beam is in contact with a three-parameter elastic foundation. Nonlinear component of the foundation may be of the hardening or softening type. Equilibrium equations of the clamped beam are obtained within the framework of von Karman assumptions and third-order shear deformation theory and solved using the two-step perturbation technique. It is shown that when the FGM beam is in contact with a sufficiently soft foundation, the post-buckling path of the heated/compressed FGM beam is unstable and therefore, the structure is imperfection sensitive. Communicated by Chandrika Prakash Vyasarayani [ABSTRACT FROM AUTHOR]

This paper proposes a disturbance rejection method with extended state observer (ESO) and a tracking differentiator (TD) to realize vibration suppression of all-clamped plate structure in the presence of lumped disturbance, i.e. internal dynamic uncertainties, unknown external forces and accelerometer measurement noises. First, the structure is modeled as two degrees of freedom system based on vibration characteristics. Second, an ESO is employed to ensure the vibration suppression performance by estimating the lumped disturbances and compensating these disturbances via real-time feedforward mechanism. Meanwhile, a TD is introduced to eliminate the influence of the measurement noises. Moreover, the stability of the closed-loop system is discussed in detail. Finally, the proposed controller is verified on the hardware-in-loop plat-form based on NI PCIe-6343 data acquisition card. Theoretical analysis and experimental results show that the proposed method possesses good vibration suppression performance. [ABSTRACT FROM AUTHOR]

According to the need of cable force monitoring of space cable structure, a new fiber Bragg grating monitoring method is proposed by analyzing the mechanism, advantages and disadvantages and application scope of existing cable force monitoring methods. The results of practical engineering show that: the mechanism of this method is clear and easy to implement; the advantages of clamp cable, tension meter, and Jack monitoring method are fully used to avoid their disadvantages; in the mutual check stage of Jack and clamp cable tension meter, the monitoring data error of the two testing methods is less than 5%, which indicates that the clamp strain gauge is accurate and effective; this method has little influence on construction, and can make full use of the engineering project The clamp cable tension meter is arranged in the process of cable tension in stages, which can realize the implementation without affecting the original construction process. It provides an experience reference for similar cable tension process and cable force control in service stage in the future. [ABSTRACT FROM AUTHOR]

This article presents novel control strategies for a seven-level (7L) T-type active neutral-point-clamped (T-ANPC) converter based on the level-shifted pulse width modulation (LS-PWM) technique. Compared with classical 7L topologies, such as NPC, flying capacitor converter, and cascaded H-bridge converter, the 7L T-ANPC converter can reduce the device requirements while reserving the advantages of high redundancy and low conduction losses. Furthermore, the internal switching state redundancy provides freedom to balance the flying capacitor (FC) voltage and realize the fault-tolerant operation flexibly. The control strategy with modified LS-PWM technique is developed for the T-ANPC to obtain desired outputs under normal and switch open fault modes. The proposed control strategy considers the complete balancing of dc-link neutral-point voltage and FC voltages. The feasibility of the proposed 7L T-ANPC and control strategy is evaluated by simulations and experimental tests under steady-state and several typical transient operating conditions. [ABSTRACT FROM AUTHOR]

Summary: The present study aims to present a new interleaved soft‐switched high step‐up DC–DC converter, which is suitable for renewable energy sources, by integrating built‐in transformer. A high conversion ratio is achieved by adjusting the turns ratio of the built‐in transformer and duty cycle. The proposed converter uses active clamped circuit, which provides zero‐voltage switching (ZVS) and a zero‐current switching (ZCS) operation for all switches and diodes, respectively. Therefore, the losses caused by reverse recovery are considerably alleviated by providing ZCS condition in the diodes. The proposed structure has some advantages such as low‐voltage stress across power switches, very low‐input current ripple, fewer components, and lower cost. The MOSFET with low drain‐source resistance can be used due to the low‐voltage stress, which could reduce conduction losses. Furthermore, a 500‐W, 48‐V input to 380‐V output laboratory prototype is built and tested to validate the performance of the proposed topology. [ABSTRACT FROM AUTHOR]

• We proposed an innovative clamp reinforcing technique for the main leg and diagonal members of operational transmission towers. • We conducted an experiment on transmission tower reinforced with clamps. • We analyzed the synergy between the original and retrofitting members in the reinforced transmission tower. • We analyzed the failure modes of a transmission towers under wind loads based on an experiment, and compared the numerical simulation and experimental results. • Further, We developed formulas for computing the ultimate loads of reinforced compound members under eccentric compression. Transmission towers frequently collapse under extreme weather conditions such as strong winds. To ensure the stability of existing transmission towers, we propose an innovative clamp reinforcing technique for the main leg and diagonal members of operational transmission towers. This technique employs star-shaped plates with stiffeners, angle steel clamps, connecting plates, and bolts to connect the reinforcing members to the original members of the transmission tower without drilling or welding. It was demonstrated by performing sub-assemblage tests that the ultimate bearing capacity of the reinforced structure can be enhanced by 21.96% compared with the original structure while maintaining a strong synergy between the reinforcing and original members. Finally, a formula for computing the ultimate loads of reinforced compound members under eccentric compression is proposed along with a method for calculating the section coefficient, and 40 sets of eccentric compressed members were employed as samples for verification. The findings of the study can serve as a theoretical analysis basis for the retrofitting design of transmission towers. [ABSTRACT FROM AUTHOR]

Bamboo is a rapid-growing plant that is a sustainable candidate to replace highly contaminating materials in housing projects. Bamboo slats are a promising alternative to using bamboo culms, as they have a higher bulk density, can be easily extracted from defective culms, and have a geometry that can be more easily controlled to standard dimensions. This study proposes joints for bamboo slats to be used in the frameworks of shear walls. To this end, three connections for Guadua bamboo slats were proposed and tested under monotonic loading to determine their moment-rotation behavior. A first joint to connect two slats was composed of two platens that compressed the slats along their wall thickness by tightening bolts. Monotonic tests of this joint showed its high ductility (range 9.5 – 38.8) and results dependent on bolt grade since the rotational stiffness and the ductility for grade-2 bolts were about 1.3 and 2.0 times significantly different than those for the specimens with grade-5. Two other proposed joints for multiple-slat members were composed of bamboo pins, platens, bolts, wood wedges, stainless steel sheets, and self-tapping screws. Significant differences were not found in the ductility and rotational stiffness of these two joints, which were in the range of 1.7–4.2, and 4954–8984 N-m/rad, respectively. However, the maximum moment (range 1172–1362 N-m) for the joint with a cedar wedge was around 1.5 times significantly higher than that (range 782–942 N-m) with a steel clamp. The multiple-slat joints displayed a relatively high ductility, while other mechanical parameters were similar to those reported in the literature for joints connecting members of substantially higher cross sections. The use of moment-resistant joints may improve the mechanical performance of shear-wall frameworks under seismic loading, enhancing the versatility of the system and providing alternatives to extend the application of bamboo for housing. • One single-slat and two multiple-slat joints for shear wall frames were proposed. • The single-slat joint under bending displayed high ductility and efficiency. • The multiple-slat joints showed the capacity to transmit moments and were ductile. • Longitudinal fissuring was the predominant failure mode. • The proposed joints can enhance the versatility of shear wall systems. [ABSTRACT FROM AUTHOR]

The rapid rate of charging and discharging, along with the high power density exhibited by dielectric energy storage films, has attracted considerable attention. However, the limited energy density hinders the broader utilization of dielectric energy storage films. The clamping relationship between the intensity of polarization and the breakdown electric field imposes a clear constraint on further enhancing the energy storage density in dielectric films for energy storage. We inserted BiMg 2/3 Nb 1/3 O 3 into Bi 4 Ti 3 O 12 , thereby promoting the formation of a defect dipole system characterized by an enhanced polarization intensity to address the aforementioned issues. Furthermore, the incorporation of La3+ ions intensified defect polarization intensity in Bi 5 Ti 3 Mg 2/3 Nb 1/3 O 15 film, optimized relaxation behavior, widened the band gap, and reduced oxygen vacancy concentration. The synergistic enhancement of polarization intensity, breakdown of electric field, and relaxation behavior can be achieved. The clamping relationship among polarization intensity, breakdown electric field and relaxation behavior is resolved within a specific range in this study. Finally, the Bi 4 LaTi 3 Mg 2/3 Nb 1/3 O 15 film enables the achievement of a high recyclable energy density (96.3 J/cm3 @ 3137 kV/cm) and superior energy efficiency (η ∼ 82.2 %). The present study introduces a novel idea to overcome the clamping relationship and attain improved energy storage performance. [Display omitted] • The Bi 5 Ti 3 Mg 2/3 Nb 1/3 O 15 films were designed by incorporating a layer of Bi(Mg 2/3 Nb 1/3)O 3 into the matrix of Bi 4 Ti 3 O 12. • By incorporating La3+ ions as dopants to regulate the defect dipole, dipole-dipole interaction, band gap, and grain size. • The relaxation performance, BEF and polarization intensity in the BL x TMN (x = 1.0) film are all enhanced. • The BL x TMN (x = 1.0) film achieves an impressive energy density of 96.3 J/cm3 and maintains a high efficiency of 82.2%. [ABSTRACT FROM AUTHOR]

• Analysis of the effect of axial constraint force on the bending energy absorption of square tubes based on three-point-bending and fully clamped bending experiments. • FE models of square tubes under variable axial constraint condition are established and verified. • Deformation and energy adsorption effect of square tubes under variable axial constraint condition. • Theoretical analysis is conducted on square tubes under three different types of variable axial constraint properties. Thin-walled tubes in the actual engineering structure (e.g., autobody) are usually connected to other structure, and the boundary constraint condition at both ends of tubes are usually very complex when bending deformation occurs under transverse loading. This paper aims at the effect and mechanism of axial constraint on the bending energy absorption effect of thin-walled tube under limited and variable axial constraint condition at both ends. A typical of thin-walled tube, square tube, is taken as an example. Firstly, we compare the experiment results of square tube under transverse loading with three-point-bending condition and fully clamped condition, revealing that the axial constraint force has a significant effect on the energy absorption effect. After that, a FE model of the square tube under variable axial constraint condition at both ends is established and validated based on experiment. Based on the validated FE model, the effect of different sizes of axial constraint stiffness on the bending energy absorption of square tube are investigated, and it is found that it has a significant effect on the deformation mode and bending energy absorption. With the increase of axial constraint stiffness, it will mainly affect the latter segment of the force–displacement curve in the bending process, which increases the bending energy absorption. Finally, theoretical models are developed to predict the force–displacement curves and bending energy absorption of the square tube under three different types of variable axial constraint properties: linear axial constraint, unequal linear axial constraint and nonlinear axial constraint. [Display omitted] [ABSTRACT FROM AUTHOR]

Closed-form unified solutions using the distributed transfer functions (DTFs) method are presented for the first time for the static short/open-circuit sensing and voltage/charge actuation of moderately thick beam cantilevers with co-localized surface-bonded piezoelectric patches. For this purpose, the smart beam is divided into three segments, of which the clamp and free sides parts are elastic, while the middle one is made of an elastic core sandwiched between two electroded piezoelectric patches. The latter can be different in material properties and thickness but should have the same length, and their widths can be different from the host elastic beam. The theoretical formulation is based on Timoshenko's first-order shear deformation theory for the kinematics and piezoelectric constitutive equations and the principle of virtual works for the variational equations. The latter integrate explicitly the physical equipotential constraints on the patches electrodes. The balance equations and boundary conditions are derived for the three segments independently and then connected at their interfaces by the equilibrium equations and continuity conditions. The unified static solutions for the resulting four problems are derived analytically in closed form using the DTF approach. These are validated against only open literature benchmarks having tabulated results or analytical formulas in order to avoid curves induced inherent additional deviations. Very good correlations were obtained in comparison with the found reference two-dimensional (2D) plane strain/stress analytical and 2D plane strain/stress and three-dimensional finite element results. [ABSTRACT FROM AUTHOR]

Summary: This paper develops model predictive control with a finite control set (FCS‐MPC) for a static synchronous compensator (STATCOM) based on hybrid cascaded H‐bridge and neutral point clamped (HC‐HNPC) multilevel inverter. By applying FCS‐MPC to basic multilevel structures such as the cascaded H‐bridge (CHB), the dynamic performance is improved; but, as the number of output voltage levels increases, the method suffers from a high computation burden as a result of a significant number of switching states. In HC‐HNPC based STATCOM, the number of power switches and switching states is reduced compared to CHB STATCOM for an equal number of output voltage levels. As a result, while keeping the number of output voltage levels the same as CHB, the FCS‐MPC computational burden decreases, and the control objectives are achieved easier. Furthermore, HC‐HNPC STATCOM as a hybrid multilevel STATCOM contains different types of cells with different capacitors voltage. Utilizing the introduced FCS‐MPC, each capacitor voltage is kept balanced without using a complex balancing system. For a detailed investigation, a single‐phase 9‐level HC‐HNPC is employed in this research. The FCS‐MPC control is developed for 9‐level HC‐HNPC STATCOM and the mathematical equations are extracted. Finally, the control performance is verified by simulation and validated with experimental results. [ABSTRACT FROM AUTHOR]

Support-induced membrane action can enhance the resistance, while altering the failure pattern, of reinforced concrete (RC) members under static/dynamic loadings. Nevertheless, the membrane effect on the load-response is regarded as a safety factor in current design guides, hence, a thorough understanding of the resistance capability of RC members in the presence of membrane actions is considered essential. To quantitatively depict the membrane behavior and its influence on the blast-resistance and failure pattern of Hybrid Fiber Reinforced-Lightweight Aggregate Concrete (HFR-LWC) beams, a specially built end-constraint clamp is developed to provide membrane actions on the structural component subjected to the blast load simultaneously. A series of field tests are conducted to investigate the dynamic behaviors of the HFR-LWC beams under close-range detonations. Overpressure-time histories of shock waves induced by the close-range explosive charge are captured. Then the deflection-responses and failure modes of the HFR-LWC beams are further investigated. The responses of the clamped HFR-LWC beam under blast loadings can be well simulated, and the blast-resistances of the beam-type members with membrane action are evaluated reasonably. The results show that membrane action is beneficial for the bridging effects of hybrid fibers and the interlocking effects of coarse aggregate, thereby giving rise to the ductile failures of HFR-LWC beam. The maximum deflections of the clamped HFR-LWC beam decrease by about 60% compared with simply-supported HFR-LWC beam in this paper, illustrating that the blast-resistance may be seriously underestimated if the membrane effects are ignored in structural design. [ABSTRACT FROM AUTHOR]

The present work attempts to investigate the influence of hygrothermal environments on the buckling of soft‐core sandwich plates with laminated composite face sheets. The stability equations are derived based on piecewise low‐order shear deformation theory (PLSDT) and then solved using different methods, depending on the boundary conditions. For fully simply supported sandwich plates, an analytical method is developed which results in some closed‐form solutions. For sandwich plates with two parallel simply supported edges and two clamped edges, a semi‐analytical solution is established using one‐dimensional generalized differential quadrature (GDQ) technique. Finally, for fully clamped sandwich plates, two‐dimensional GDQ approach is applied to the governing equations. To validate the results of proposed methods, a comparative study with various examples is carried out verifying that the methods in the present work can accurately predict the buckling load of sandwich plates in hot and wet environments. Then, a comprehensive parametric study is performed to show the effects of temperature and moisture content on the buckling of sandwich plates for different parameters such as length‐to‐thickness ratio, core thickness, and boundary conditions. It is concluded that both temperature and moisture content have significant influences on the buckling behavior of sandwich plates. [ABSTRACT FROM AUTHOR]

Exotic domain-wall phenomena make ferroelectrics the candidates for nanoelectronics. The local symmetry and structure anomalies at domain walls have raised interest in the unusual functionalities, such as domain wall chirality and conductivity. Especially, the spontaneous lattice distortion and symmetry breaking at domain walls activate them as the location of structural transformation. However, the routes to achieve ferroelectric-antiferroelectric phase transition via ferroelectric domain walls remain challenging, which are important to develop materials for energy storage and conversion. Here, we have observed stepwise antiferroelectric phase transition in strained pure BiFeO 3 ultrathin films derived from ferroelectric domain walls. Aberration-corrected transmission electron microscopy observation reveals that the resultant phase transition is mediated by dense 180° domain walls via providing the antiparallel cation displacement, cooperating with the enhanced interfacial oxygen octahedral clamping. First-principles calculations further confirm the critical role of interfacial oxygen octahedral coupling during this transition. These findings report an alternative route for antiferroelectric phase transition. Besides, our results provide fresh insights into functionalities of ferroelectric domain walls and open a venue for developing energy-storage materials based on domain engineering. Image, graphical abstract [ABSTRACT FROM AUTHOR]

This article provides a summary of the design and operating parameters for an emergency conveyor belt clamp. The static clamp is hydraulically opened and spring control closed to apply a braking force to a belt when there is no hydraulic pressure keeping the clamp faces apart. The braking force is either on or off and not continuously variable during operation. The clamp is designed to be 'fail safe' with the clamp closing when hydraulic pressure is lost. Hand calculations were used along with finite element analysis to determine the structural stresses induced by the combined clamping force and belt tension. A twenty Metric Tonne belt capacity (196.1kN lateral load) has been nominated for design purposes. A belt thickness of 50mm has been assumed as a worst case for design purposes. In addition, a dynamic coefficient of friction of 0.2 has been assumed for the contact surfaces between the belt and the clamping beam surfaces. AS1418.1 - Cranes, Hoists and Winches General and AS3990 Mechanical Equipment - Steelwork have been utilized for determining the suitability of the design. The design meets the requirements of the standards for the proposed clamping loads and belt tensions. The combined stresses do not exceed allowable stress or displacement recommendations. [ABSTRACT FROM AUTHOR]

The contact pressure distributions are initially analyzed by conducting structural simulations on a single cell and a 40-cell stack of proton exchange membrane fuel cell (PEMFC) at various clamping pressures. The corresponding experimental pressure-sensitive film distributions are obtained that shows a good agreement with the simulation results. Then, the experimental and simulation data are compared by transforming images of pressure-sensitive film from experiments into detailed contact pressure data. The contact pressure uniformity of the simulation and experiment are compared by introducing mean pressure error and fluctuating intensity, and the optimal pressure range for best contact pressure uniformity is determined to be between 1.25 MPa and 1.67 MPa. Finally, CFD simulation approach is utilized to assess the electrical output performance. When comparing interface contact resistance (ICR) to porosity, the results indicate a reduction in power density of 5.1% and 1.2% at low clamping pressure compared to the case without taking ICR and porosity into account, while it decreases by 7.5% and 6.3% under high clamping pressure, respectively. It also deduced that there exists an optimal clamping pressure range for the best electrical output performance. The optimal clamping pressure is approximately 1.33 MPa, which is consistent with the previous structural results. In summary, experiments and numerical calculations of structure and fluid are carried out in this study to comprehensively evaluate the influence of clamping pressure on the structural and electrical performance of the PEMFC, the methods of experiments and simulations can offer guidance on the stack assembly process in practical applications. • Contact pressure uniformity is comprehensively analyzed by simulation and experimental methods. • Fitting relationship between grayscale of experimental data and contact pressure is established. • The electrical output power density considering interfacial contact resistance is determined. • The optimal clamping pressure are systematically analyzed by structural and fluid simulation. [ABSTRACT FROM AUTHOR]

Resonant sensors are widely used, especially in microsystems, for their high sensitivity, dynamic range, and resolution. In a typical resonant sensor, the measurand is converted to an axial force on a resonating beam, affecting its effective stiffness and consequently causing a shift in its resonance frequency. For a given operating frequency, it is desired to maximize the sensitivity of the resonance frequency to this axial force. In this paper, we propose new structural designs that significantly improve the sensitivity of resonant sensors to axial force. Our approach relies on structural modifications to resonant beams, including their boundary conditions, and hence, is amiable for implementation in different microfabrication processes. We present a mathematical model which is confirmed through simulations. Test devices were fabricated and used to validate the design principles. Our experimental findings indicate a sensitivity improvement of over four-fold for the test devices compared to the standard clamped-clamped beam structure. Without any modification to a fabrication process, the design principles presented in this work can be utilized to improve the performance of most micro- and nano-device designs that rely on conventional resonant beam force sensors. [Display omitted] • New micromechanical design approach proposed for resonant sensors. • These designs yield significant improvement in sensitivity to axial force. • Design principle modifies boundary conditions for resonant force sensors and is proven through modelling and simulations. • Sample devices fabricated and tested, supporting the proposed approach's utility. • Applicable to most device designs as direct replacements for the conventional resonance clamped-clamped beam force sensor. [ABSTRACT FROM AUTHOR]