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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]

Inchworm piezoelectric actuators have attracted much attention in the field of precision positioning due to the advantages of a large stroke, high output force, and high resolution. However, traditional inchworm piezoelectric actuators use two sets of clamps and a set of drive structures to achieve stepping motion, which generally requires at least three piezoelectric stacks, resulting in a complex structure and the control system. Several methodologies have been advanced to minimize the utilization of piezoelectric stacks. However, there still exists the issue of excessive volume. Therefore, an inchworm piezoelectric actuator with a single-clamp and single drive structure is proposed in the study, which provides a compact size and smaller volume. The clamping mechanism comprises two sets of clamping feet with opposite displacement, which alternate contact with the guide frame and adjustable plate to ensure that the clamping mechanism always has frictional force and accomplishes the stepping motion. The testing of the actuator's step distance, output force, and other parameters was conducted utilizing a displacement sensor. Experimental results indicate that the actuator achieved a maximum speed of 174.3 μm/s and an output force of 8.6 N when the frequency and voltage were 19 Hz and 150 V. [ABSTRACT FROM AUTHOR]

Reaming is a crucial technology in finishing operations, demanding high stability in the machining process for optimal results. The clamping system significantly influences the dynamic properties of the system tool -- clamping - machine and is key in mitigating chatter. The introduction of new designs in clamping exchangeable reaming heads presents several challenges, particularly in terms of vibration suppression. This study explores various constructions of clamping bars, examining their dynamic properties in both static conditions and during machining. Through these evaluations, the research aims to understand how different designs impact the stability and effectiveness of reaming operations. The measured data from these experiments reveal how the construction of the holder influences machining process stability, providing insights into optimizing clamping system designs for improved reaming performance. the outcomes of this study contribute to the development of more effective and efficient clamping systems for finishing operations. [ABSTRACT FROM AUTHOR]

The reverse engineering (RE) process is often necessary in today's engineering and medical industries. Expertise in measurement technology, data processing, and CAD modeling is required to ensure accurate reconstruction of an object's geometry. However, errors are generated at every stage of geometric reconstruction, affecting the dimensional and geometric accuracy of the final 3D-CAD model. In this article, the geometry of reconstructed models was measured using contact and optical methods. The measurement data representing 2D profiles, 3D point clouds, and 2D images acquired in the reconstruction process were saved to a stereolithography (STL) model. The reconstructed models were then subjected to a CAD modeling process, and the accuracy of the parametric modeling was evaluated by comparing the 3D-CAD model to the 3D-STL model. Based on the results, the model used for clamping and positioning parts to perform the machining process and the connecting rod provided the most accurate mapping errors. These models represented deviations within ±0.02 mm and ±0.05 mm. The accuracy of CAD modeling for the turbine blade model and the pelvis part was comparable, presenting deviations within ±0.1 mm. However, the helical gear and the femur models showed the highest deviations of about ±0.2 mm. The procedures presented in the article specify the methods and resolution of the measurement systems and suggest CAD modeling strategies to minimize reconstruction errors. These results can be used as a starting point for further tests to optimize CAD modeling procedures based on the obtained measurement data. [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]

Silicon carbide fiber reinforced silicon carbide matrix (SiCf/SiC) composite is the key cladding material of nuclear fuel, which determines the safety and reliability of nuclear fuel storage and transportation. The replacement of its storage and transportation scenario needs to be completed by the manipulator, but the application of SiCf/SiC wear, fracture, and nuclear leakage in the snatching process of brittle-flexible-rigid contact in the irradiation environment has been seriously restricted due to unclear understanding of the damage mechanism. Therefore, the effects of irradiation dose and clamping load on the friction characteristics of the contact interface between SiCf/SiC clad tube are studied in this paper, and the effects of irradiation parameters and clamping force on the static friction coefficient of the contact interface between the clad tube and flexible nitrile are obtained. Based on the Greenwood-Williamson tribological model, a numerical model of the shape and structure of the contact micro-convex at the micro-scale of the clamping interface is constructed by introducing the multi-surface integral, and finally verified by experiments. The research results show that there is a unique "Irradiation suppression zone" under the clamping condition of SiCf/SiC cladding tube under the nuclear irradiation environment, and the growth of static friction coefficient slows down until stagnates after irradiation reaches a certain extent (600 kGy), and there will be a decline when the irradiation dose continues to increase, among which the clamping force of 15.2 N within the irradiation interval of 1,000 kGy can meet the safety of nuclear environment operation. The results of this paper can provide an important theoretical basis and application guidance for the safe operation of SiCf/SiC cladding tubes in the storage and transportation clamping process. [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]

This paper introduces a new single‐input multi‐output step‐up DC/DC converter with soft‐switching performance and low input current for renewable energy applications. The proposed topology uses a three‐winding coupled‐inductor (TWCI) and voltage multiplier circuits to achieve high voltage gains. The bipolar output voltages of the proposed converter can be varied independently by tuning the turns ratios of the TWCI. Due to the semi‐trans‐inverse specification of the suggested topology, high voltage gains can be obtained under a lower number of turns ratio in the magnetic device. Furthermore, a regenerative passive clamp technique mitigates the voltage stress on the single power switch. Additionally, the power dissipations are further reduced by considering a resonant tank in the circuit. In the converter, the parasitic leakage inductances of the TWCI windings help to provide the soft‐switching conditions for the switch and also to eliminate the reverse‐recovery loss for all converter diodes. The operating mode of the presented converter has been introduced and the steady state, along with the main operating equations have also been derived. Finally, the theoretical analysis is verified by a sample prototype 235 W at the input voltage 25 V and outputs of 200 V and −200 V. [ABSTRACT FROM AUTHOR]

In the present study, the effect of non-linear thickness variation and that of Winkler's foundation is investigated on radially symmetric vibrations of bi-directional FGM circular plates subjected to uniform in-plane peripheral loading. It is considered that the elastic modulus, as well as density of the FGM, varies in two mutually perpendicular directions (i.e., radial and transverse). This variation follows the power law. However, the variation in thickness of FGM plate varies along the radial direction and follows quadratic variation. Hamilton's principle is used to obtain the coupled differential equations governing the motion. The approximate solutions of these equations for simply supported and clamped edge conditions are obtained by an elegant numerical technique: the Harmonic differential quadrature method. The effect of density parameter, gradient index, heterogeneity parameter, taper parameters, and thickness parameter of the plate is analyzed on the vibration characteristics for the first two modes of vibration for different values of foundation parameter together with in-plane peripheral loading parameter. Furthermore, critical buckling loads in compression by taking the frequencies zero are evaluated for both plates. The validity of the current approach is established by comparing the frequency parameter with true values and with the results of other authors. [ABSTRACT FROM AUTHOR]

This article proposes a hierarchical control strategy to address semi-ABS control as well as the precise clamping force control problems for an integrated electric parking brake (iEPB) system. To this end, a detailed system model, including modeling of the motor, transmission mechanism, friction and braking torque, is constructed for controller and observer design, and a sliding-mode-based observer (SMO) is proposed to estimate the load torque by using the motor rotational speed without installing a force sensor. In addition, a stable and reliable tire–road friction coefficient (TRFC) estimation method is adopted, and the desired slip ratio (DSR) is observed as the target that the rear wheels cycle around. At the upper level of the hierarchical control structure, the desired clamping forces of the rear wheels are generated using a sliding mode control (SMC) technique, and the control objective is to track the DSR to make full use of the road condition. At the lower level, the motor is controlled to track the desired clamping force generated from the upper controller. The hardware-in-the-loop (HIL) experimental results demonstrate the effectiveness and high tracking precision of the proposed strategy under different road conditions, and the estimation parameters based on the proposed observers are timely and accurate to satisfy the control requirements. [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]

With the evolution of the aerospace industry, structures have become larger and more complex. These structures exhibit significant characteristics such as extensive flexibility, low natural frequencies, numerous modes, and minimal structural damping. Without implementing vibration control measures, the risk of premature structural fatigue failure becomes imminent. In present times, the installation of inertial actuators and control signal acquisition units typically requires independent setups, which can be cumbersome for practical engineering purposes. To address this issue, this study introduces a novel approach: an independent control unit combining a loudspeaker-based inertial actuator (LBIA) with an integrated piezoelectric ceramic sensor. This unit enables autonomous vibration control, offering the advantages of ease of use, low cost, and lightweight construction. Experimental verification was performed to assess the mechanical properties of the LBIA. Additionally, a mathematical model for the LBIA with an integrated piezoelectric ceramic sensor was developed, and its efficacy as a control unit for thin plate structure vibration control was experimentally validated, showing close agreement with numerical results. Furthermore, the LBIA's benefits as an actuator for low-frequency mode control were verified through experiments using external sensors. To further enhance control effectiveness, a mathematical model of the strain differential feedback controller based on multi-bandpass filtering velocity improvement was established and validated through experiments on the clamp–clamp thin plate structure. The experimental results demonstrate that the designed LBIA effectively reduces vibration in low-frequency bands, achieving vibration energy suppression of up to 12.3 dB and 23.6 dB for the first and second modes, respectively. Moreover, the LBIA completely suppresses the vibration of the fourth mode. Additionally, the improved control algorithm, employing bandpass filtering, enhances the effectiveness of the LBIA-integrated sensor, enabling accurate multimodal damping control of the structure's vibrations for specified modes. [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]

Clamping force control is one of the key technologies in the algorithm design and implementation of electro-mechanical braking system, whose control effects directly affect the vehicle braking performance and safety performance. In order to improve the clamping force control performance of electro-mechanical braking (EMB) system, an EMB clamping force control method based on Variable universe adaptive fuzzy PID (VUF-PID) controller is proposed, and stretching factors are added to the fuzzy PID control. According to the operation of the controlled object, the fuzzy theory domain can be adjusted in real time to keep the system in the proper parameter value and improve the adaptive ability of the system. The response characteristics and effectiveness of clamping force under step braking condition, gear switching braking condition and sine braking condition are verified by simulation experiments using MATLAB/Simulink. The results show that the proposed VUF-PID control method has strong tracking characteristics and stability characteristics, and meet the braking requirements under different braking conditions. [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]

Aiming at the problems of complex realization, single control target and difficulty in selecting the optimal zero sequence voltage when the traditional space vector PWM (SVPWM) algorithm is adopted in five‐level active neutral‐point‐clamp (5L‐ANPC) converter, a predictive control optimal switching sequence selection (PC‐OSSS) method is proposed. The method adopts the SVPWM control strategy base on the line voltage coordinate and then realizes the selection of optimal switching sequence through the multi‐objective predictive control method. Firstly, the principle of SVPWM based on line voltage coordinate is introduced, and all switching sequences that can be output are obtained. Secondly, the mathematical models of the floating capacitor (FC) voltage, the neutral point (NP) voltage and the common mode (CM) voltage corresponding to each switch sequence are established. Finally, the optimal switch sequence is selected by using the predictive control method based on priority ranking. Compared with traditional SVPWM, the outstanding advantage of this method is that the traditional qualitative comparison method is replaced by quantitative calculation. The multi‐objective control performance of the converter is improved while retaining the advantages of the traditional SVPWM fixed frequency. Finally, the practicability and effectiveness of the proposed control strategy are verified by simulation and experiment. [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]

Cantilever workpieces are widely used in the aerospace field; they produce vibrations easily and affect machining quality under the action of external forces. Enhancing the stiffness of the workpiece using a robot as a fixture is an effective means to solve this problem. However, the vibration suppression effect of the clamping system depends on the dynamics performance of different configurations of the robot. Therefore, in order to obtain the optimal clamping robot configuration, the system dynamics model composed of automated guided vehicle (AGV)-robot-gripper-workpiece (ARGW) is established based on the transfer matrix method of the multibody system (MSTMM), and the vibration responses of the workpiece under different configurations are analyzed. Then, a robot configuration optimization method based on workpiece response was proposed. Finally, the effectiveness of the optimization method is verified through simulations and experiments at different clamping robot configurations. The dynamics model and optimization method in this paper can be used to predict the workpiece vibration response and choose a reasonable clamping robot configuration, avoiding the reduction in workpiece machining quality due to the improper configuration of the clamping robot. [ABSTRACT FROM AUTHOR]

Manufacturing process accuracy is obtained by proper arrangement of fixture elements known as fixture layout. A N-3-2-1 method is used for sheet metals which requires (N + 3) fixture elements to constrain deformation normal to surface. Genetic Algorithm (GA) is used for fixture layout optimization, but it requires high computational effort due to large number of populations. A new method for fixture layout optimization is proposed by integrating topology optimization into GA. In this method, topology optimization reduces the population for GA. The objective function is to reduce the population for GA and minimize total deformation normal to the plane of workpiece. The proposed approach comprised three stages. In the first stage, the initial number of clamps are determined. In the second stage, the population is reduced for GA and the feasible area of clamps are identified using the topology optimization technique. In the third stage, the number and position of clamps, earlier identified in stage one, are optimized using GA. Two different case studies are solved by varying applied load position and magnitude. The proposed method results 47.5% and 65% decreases in the population for subcase 1 and subcase 2, respectively. However, in subcase 3 and subcase 4 the population reduced was 90% and 80%, respectively. The 25% of reduced population is used as the convergence criteria. Similarly, total deformation normal to the plane is reduced in each subcase, with the highest reduction of 86.31% in subcase 1 and lowest of 59.85% in subcase 4. The experiment is performed on the first case study to validate results. This concludes that the proposed method is valid and that optimal results are found. [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]

The development of adaptive and intelligent clamping devices allows for the reduction of rejects and defects based on weld discontinuities in laser-beam welding. The utilization of fixture-integrated sensors and actuators is a new approach, realizing adaptive clamping devices that enable in-process data acquisition and a time-dependent adjustment of process conditions and workpiece position by means of a closed-loop control. The present work focused on sensor and actuator integration for an adaptive clamping device utilized for laser-beam welding in a butt-joint configuration, in which the position and acting forces of the sheets to be welded can be adjusted during the process (studied welding speeds: 1 m/min, 5 m/min). Therefore, a novel clamping system was designed allowing for the integration of inductive probes and force cells for obtaining time-dependent data of the joint gap and resulting forces during welding due to the displacement of the sheets. A novel automation engineering concept allowed the communication between different sensors, actuators and the laser-beam welding setup based on an EtherCAT bus. The subsequent development of a position control and a force control and their combination was operated with a real time PC as master in the bus system and proved the feasibility of the approach based on proportional controllers. Finally, the scalability regarding higher welding speeds was demonstrated. [ABSTRACT FROM AUTHOR]

The aim of the study is to present a new approach to the analytical solution of the vibration and stability problem of clamped sandwich cylindrical shells (SCSs) covered by functionally graded (FG) coatings under an axial compressive load in the framework of shear deformation theory (ST). After modeling the micro and macro mechanical properties of FG coated SCSs with various configurations, the constitutive relations and basic equations are derived depending on the stress, deflection and two angles of rotation functions using modified Donnell type theory. An attempt is made to analytically solve the fundamental differential equations for SCSs covered by FG coatings using novel approximation functions satisfying the clamped boundary conditions. Three different shear stress functions (SSFs) such as parabolic shear stress function (Par-SSF), cosine-hyperbolic shear stress function (Cos-Hyp-SSF) and uniform shear stress function (U-SSF) are used in the analysis. After confirming the accuracy of the obtained results, the influences of coating profiles, volume fractions and layer arrangement variations on the critical parameters for three different transverse shear stress functions are investigated in detail. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

In this paper, we mainly aimed to design a reduced-order extended state observer-based active vibration controller for a structural vibration control system with total disturbances, i.e., model uncertainties, higher harmonics, and external excitations. A reduced-order extended state observer (RESO)-based nonsingular terminal sliding mode vibration control (RESO–NTSMVC) method is proposed for the vibration suppression of an all-clamped plate structure with an inertial actuator. First, a second-order state space model of the thin plate, with an inertial actuator, was established by solving the dynamic partial differential equation and analyzing the physical model. Second, the total disturbances, i.e., model uncertainties, higher harmonics, and external excitations, were estimated and compensated for by using a RESO via a feedforward part. Third, a NTSMVC based on an estimated value was designed to obtain a fast-tracking rate and effective vibration suppression performance. In addition, the stability of the closed-loop system was proven by using a Lyapunov stability criterion. Finally, a semi-physical experimental instrument was built based on the MATLAB/Simulink real-time environment and the NI-PCIE6343 acquisition card to verify strong anti-disturbance performance and effective vibration control performance of the designed method. The experimental comparison results showed that the vibration amplitudes of the proposed method could be reduced by 11.7 dB, when the traditional extended state observer-based nonsingular terminal sliding mode vibration control (ESO–NTSMVC) method achieved a control effect of only 6.5 dB. The comparative experimental results showed that the proposed method possessed better vibration suppression performance and anti-disturbance performance. [ABSTRACT FROM AUTHOR]

To improve the automation, welding efficiency, and welding quality of duckbill welding of the cotton seeder, this study designed a cotton seeder duckbill welding robot. According to the characteristics of the duckbill weldment and welding requirements, the overall structure of the welding robot was determined, including the girdle feeding mechanism, static duckbill feeding mechanism, hinge feeding mechanism, welding fixture, welding actuator, and control system. To realize the continuous automatic feeding, positioning, fixing, welding, and unloading of the workpiece in the duckbill welding, the feeding mechanism adopts the method of cooperative cooperation of inductive proximity switch, electromagnet, and cylinder. The main body of the welding fixture adopts the pneumatic clamping method; the welding actuator adopts the synchronous belt module electric drive so that the welding torch can move in a straight line along the X axis and the Z axis. The welding process of the duckbill was simulated by Simufact Welding software, and the deformation and stress changes of the weldment were compared and analyzed when the single-sided single welding, the bilateral symmetrical double welding torch, two welding forms, and two welding process parameters were used to determine the welding process parameters of the welding robot. The prototype was made and the welding test was carried out. The test results show that the duckbill welding robot of the cotton seeder has stable feeding, solid clamping, accurate positioning, and high welding efficiency. According to the national standard, the appearance of the duckbill weld is inspected. The surface of the duckbill weld and the heat-affected zone has no cracks, incomplete fusion, slag inclusion, crater, and porosity. The forming quality of the welded parts is good. The design of the duckbill welding robot for cotton seeder is helpful in solving the problems of cumbersome positioning and clamping and low efficiency in manual and semi-automatic duckbill welding robots, which provides a strong guarantee for the large-scale and standardized welding production of the dibbler duckbill. [ABSTRACT FROM AUTHOR]

The traditional clamping-sequence optimisation of sheet-metal parts requires many complicated finite element analyses, and clamping-sequence planning does not account for the springback from clamp-release. Therefore, this paper proposes a new optimisation method based on a heuristic algorithm. We first propose a new contact model of parts, clamps and supporting locators to analyse assembly deformation. Then, we use the distance between the actual and nominal positions to evaluate the clamp layout. Finally, we apply the heuristic algorithm to optimise the clamping sequence. We illustrate the proposed method with a case study of a taillight bracket, whose results show that the method of clamping-sequence optimisation can effectively decrease the deformation of sheet metal from clamping. [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]

A new piezoelectric inchworm actuator with screw clamping mechanisms has been developed recently for the wing folding mechanism of a small unmanned aircraft where the actuator power density is a great concern. Considering that the prototype actuator was designed just with engineering intuition and the performance optimization through experimental developments would take a vast amount of cost and time, a mathematical model was developed to investigate the actuator's critical design parameters and optimize its presently undesirable performance. Based on the lumped parameter method reported previously, and taking full account of the detailed modeling of the complex actuator housing and the actual nonlinear behaviors from the high-force contact and friction occurring at the screw-nut interface, as well as the output performance of the main drive elements including the piezoelectric stack and hollow ultrasonic motors (HUSMs), this model was built and then was experimentally verified for its accuracy and availability. Finally, nine design parameters were studied for their individual effect on the actuator's output using the proposed model. The simulation results indicate that the performance can be considerably improved by performing a slight modification to the prototype, and the dynamic modeling and parameter optimization methods used in this study can also serve as a useful reference for the design of similar piezoelectric inchworm actuators with intermittent clamping behaviors. [ABSTRACT FROM AUTHOR]

Clamping is the key factor that restricts the full-process mechanization of directional shrimp peeling. To solve the problem of difficult clamping caused by the uncertainty of shrimp position after orientation, a segmented shrimp clamping method was proposed by analyzing the relationship between shrimp conveying and clamping conditions. The contact force relationship on the shrimp meat was deduced based on mechanical analysis of the clamping process, and it was concluded that the number of segmented clamping units should be increased during the clamping process to reduce the pressure of the clamping units on the shrimp meat. A segmented shrimp clamping mechanism was designed for adaptive shrimp clamping, conveying and discharging. The profile curve model of the clamping surface was built by analyzing the shrimp section profile characteristics. According to ADAMS kinematics simulation analysis, no shrimp fell off or was damaged during the clamping process, which verified the design rationality of the segmented shrimp clamping mechanism. According to the single-factor test on a newly built shrimp clamping test bench, the optimal rotation speed range of the segmented clamping mechanism was found to be 10–20 r/min, the clamping success rate was over 92%, and the shrimp integrity rate was no less than 99%. The comparison test and performance test results showed that the segmented clamping mechanism had stronger adaptability and better clamping effect under the condition of variable interval feeding. Therefore, the segmented clamping mechanism is capable of practical application and can create stable clamping conditions for shrimp peeling. [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]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]