Loading Situations Research Articles

Technoeconomic Analysis of Fuel Cell Vehicle‐to‐Grid (FCV2G) System Supported by Photovoltaic Energy

The investigation of fuel cell vehicles (FCVs) connected to grid (FCV2G) technology regarding the reduction of consumer costs is proposed. Herein, the key contribution is to investigate the energy and profit analysis aspects of an FCV2G system supported by photovoltaic (PV) panels for a 24 h operation. For this, an FCV in the rating of 100 kW is connected to the grid/homes, and a detailed analysis is performed for the FCV2G system supported by PV energy in the rating of 40 kW. The designed system is primarily tested for energy transfer from FCV/PV to grid/homes, and the results are verified for dynamic loading situations. It is observed that FCV + PV supply excess power to the grid during flexible hours of the day, and consumer homes use additional energy from the grid during peak hours. The profit analysis of the established FCV2G system is conducted using the load profile data for the 24 h situation. FCV2G supported by a PV system verifies that the homes' consumption cost is reduced significantly, and the remaining energy is utilized by selling the energy to the grid.

Moment gradient factor for steel I-beams with sinusoidal web openings

The moment gradient factor is an important parameter to be considered in the design of beams subjected to failure by Lateral-torsional Buckling. The analytical formulation to obtain the critical moment for the LTB is based on the assumption of applying a constant bending moment along the free span of the structural element. This loading situation is not usual in engineering projects, so it is necessary to correct the value of the critical moment according to the different loading situations that can be found in practical cases. Thus, many design codes worldwide assign values to perform this correction. The moment gradient factor, Cb, is determined by comparing the elastic critical moment of a beam subject to varying moment condition with that subject to a constant moment condition. When considering beams with web openings, there are currently no recommendations or proposals for calculating the moment gradient factor, considering loads applied outside the shear center. There are also no explicit recommendations in standards regarding the design of this type of structure. Recent research deals with the influence of cellular beam parameters on the moment gradient factor; however, they do not present explicit proposals for its calculation in structures of this nature. The research scenario in the literature becomes even more scarce when considering beams with sinusoidal web openings. Thus, the paper investigates this for a wide range of I-beams with openings, with the goal of analyzing the influence of the openings on the Cb, as well as proposing formulae for usual design situations. The proposals were obtained through prediction models derived from an extensive parametric study using the ABAQUS finite element software, in which 34,020 models were developed.

Autologous semitendinosus meniscus graft significantly improves knee joint kinematics and the tibiofemoral contact after complete lateral meniscectomy

PurposeThe purpose of this study was to investigate the potential of a doubled semitendinosus (ST) and a single gracilis tendon (GT) lateral meniscus autograft to restore the knee joint kinematics and tibiofemoral contact after total lateral meniscectomy (LMM).MethodsFourteen human knee joints were tested intact, after LMM and after ST and GT meniscus autograft treatment under an axial load of 200 N during full range of motion (0°–120°) and four randomised loading situations: without external moments, external rotation, valgus stress and a combination of external rotation and valgus stress using a knee joint simulator. Non-parametric statistical analyses were performed on joint kinematics and on the tibiofemoral contact mechanics.ResultsLMM led to significant rotational instability of the knee joints (p < 0.02), which was significantly improved after ST autograft application (p < 0.04), except for knee joint flexions > 60°. The GT autograft failed to restore the joint kinematics. LMM significantly increased the tibiofemoral contact pressure (p < 0.03), while decreasing the contact area (p < 0.05). The ST autograft was able to restore the contact mechanics after LMM (p < 0.02), while the GT replacement displayed only an improvement trend.ConclusionThe doubled ST lateral meniscus autograft improved the knee joint kinematics significantly and restored the tibiofemoral contact mechanics almost comparable to the native situation. Thus, from a biomechanical point of view, ST meniscus autografts might be a potential treatment alternative for patients who are indicated for meniscus allograft transplantation.

VSFPWM Based on Circulating Current Ripple Prediction for ZVS in Two Paralleled Grid-Tied Inverters With Coupled Inductors

Zero voltage switching (ZVS) control is an effective and promising way to further improve the power density, efficiency and electromagnetic interference for the two paralleled silicon carbide inverters with coupled inductors. In this article, focusing on the popular 180 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> interleaved pulsewidth modulation (PWM), the circulating current ripple prediction model is first derived as a function of operating conditions in the time-domain. With the assistance of this model, the actual trajectory of phase-leg currents can be reconstructed by superposition of sampling fundamental current and predicted circulating current ripple, without adding any high-frequency current sensor or auxiliary circuit. By carefully considering the ZVS requirement of all switches, a variable switching frequency PWM (VSFPWM) for full range ZVS control is proposed in this article. The proposed VSFPWM shows a good performance of ZVS realization in various load situations, as well as a good dynamic response of the inverter during current step change. In addition, due to the real-time variation of switching frequency, the proposed VSFPWM demonstrates the obvious advantage in conductive EMI reduction. Both the simulation and experimental results are presented to verify the effectiveness of the analysis and proposed method.

Thinned array ultrasonic imaging of debonding defects in discontinuous impedance bonded structures

Ballastless track is a typical bonding structure with discontinuous impedance. Under the influence of heavy load, deteriorating environment and other situations, the circumstance of debonding occurs frequently and seriously affects the safety of train operation. In this work, a high-precision array ultrasound fast imaging method is proposed. Based on the propagation path and time of sound wave in the medium obtained by ray tracing method, a theoretical model of sound velocity of discontinuous impedance bonding structure is established when the difference in sound velocity among dielectric layers is taken into account. High degree of freedom sparse array based on real number coding as well as synthetic aperture focusing technology (SAFT) imaging method is used to improve detection efficiency. The results of the experiments carried out on ballast less track structure are shown below. The ray tracing method can accurately calculate the propagation path and propagation time of ultrasonic wave and improve the detection accuracy. The optimized thinned array pattern has narrowed the main lobe width and low side lobe gain, which improves the detection efficiency and sound field directivity. The efficiency of thinned array SAFT imaging method is improved by 30.9% when the imaging error of debonding defects is within ±5%, which provides a theoretical support fordetecting such debonding defects.

Ant colony optimization technique optimized controller for frequency stabilization of an isolated power system with non-linearity

The load frequency control of a thermal power producing system, the ant colony optimization (ACO) approach adjusted proportional integral derivative (PID) controller is proposed. This work examines the single area thermal power system with /without generation rate constraint. For emergency situations, a PID controller is developed and used to regulate power system characteristics. This study uses the ACO method with the integral time absolute error objective function optimize controller gain values. In addition, the performance of the suggested approach is evaluated by introducing non-linearity components to the power-generating systems under study. Conventional, particle swarm optimization (PSO), and genetic algorithms (GA) approach tuned controller responses are compared with ACO. Fast settling with minimal peak and undershoots in the producing power supply of the system under emergency loading situations demonstrates the superiority of the proposed controller over competing controllers.

A Single-Source Switched-Capacitor 13-Level High Gain Inverter With Lower Switch Stress

A switched-capacitor based 13-level inverter with high gain and reduced switch stress is presented in this article. The 13-level single-phase ac output voltage is achieved with a voltage gain of 6 by utilizing a single dc source, 14 switches, 3 capacitors and 1 diode in the proposed converter. Self-voltage balancing is achieved for different types of loads without the use of complicated control schemes or supplementary circuitry. The proposed topology can generate negative polarity without a back-end H-bridge. Consequently, voltage stresses across the switches are reduced. The voltage stress across the switches is limited to 4 times the input DC voltage. Included also is an analysis of power loss for several components of the proposed converter. A comparison is made with contemporary topologies that require a single dc source at the input in terms of several performance characteristics. Resistive (R) and resistive plus inductive (R-L) loads are simulated in this study. To demonstrate the effectiveness of the suggested converter, a laboratory prototype is constructed. In order to demonstrate the viability of the suggested arrangement, the experimental results for step variation in load demand and variation in modulation index under practical loading situations are obtained.

Free-floating medial meniscus implant kinematics do not change after simulation of medial open-wedge high tibial osteotomy and notchplasty

PurposeThe purpose of this in-vitro study was to examine the kinematics of an artificial, free-floating medial meniscus replacement device under dynamic loading situations and different knee joint states.MethodsA dynamic knee simulator was used to perform dynamic loading exercises on three neutrally aligned and three 10° valgus aligned (simulating a medial openwedge high tibial osteotomy - MOWHTO) left human cadaveric knee joints. The knee joints were tested in three states (intact, conventional notchplasty, extended notchplasty) while 11 randomised exercises were simulated (jump landing, squatting, tibial rotation and axial ground impacts at 10°, 30° and 60° knee joint flexion) to investigate the knee joint and implant kinematics by means of rigidly attached reflective marker sets and an according motion analysis.ResultsThe maximum implant translation relative to the tibial plateau was < 13 mm and the maximum implant rotation was < 19° for all exercises. Both, the notchplasties and the valgus knee alignment did not affect the device kinematics.ConclusionsThe results of the present in-vitro study showed that the non-anchored free-floating device remains within the medial knee joint gap under challenging dynamic loading situations without indicating any luxation tendencies. This also provides initial benchtop evidence that the device offers suitable stability and kinematic behaviour to be considered a potential alternative to meniscus allograft transplantation in combination with an MOWHTO, potentially expanding the patient collective in the future.

A new resource sharing protocol in the light of token-based strategy for distributed system

One of the highly researched areas in distributed system is mutual exclusion. To avoid any inconsistent state of system, more than one processes executing on different processors are not allowed to invoke their critical sections simultaneously for the purpose of resource sharing. As a solution to such resource allocation issues, token-based strategy for distributed mutual exclusion algorithms as a prime classification of solutions is one of the most popular and significant ways to handle mutual exclusion in this field. Through this research article, we propose a novel token-based distributed mutual exclusion algorithm. The proposed solution is scalable and has better results in terms of message complexity compared to existing solutions. In this proposed art of work, the numbers of messages exchange per critical section invocation are 3(⌈log N⌉ - 1), 3⌈(⌈log (N + 1) ⌉ - 1)/2⌉ and 6[⌈log (N + 1)⌉ + 2(2(-⌈log (N+1)⌉) - 1)] in case of light load, medium load and high load situations respectively.

Finite element analysis and simulation of cargo fork dynamics

The forklift truck, as an industrial transport vehicle, is widely used in stations, workshops, warehouses, ports, and other places. At the same time, with the rapid development of today’s economy and the emergence of express industries, the number of forklifts in China is increasing by the day. At the same time, the accidents caused by forklifts are also increasing. The current research on forklifts mainly focuses on the dynamic and static analysis and structural optimization of the vehicle body and parts, among which there are few studies on a forklift. In order to verify the reliability of the forklift, this paper uses the function of SolidWorks Simulation to conduct finite element analysis on the dynamic characteristics of forklifts and sets the forklift’s mass as 2 tons to increase external irregular vibration. When the damping is 0.7, it is found that the maximum stress is 3333Pa. Based on the completion of the physical modeling, with the help of SolidWorks animation, the load situation of the forklift truck in different scenes is simulated. It is found that within the permissible range of strength, the greater the slope rate, the less the mass of the safe load.

Evaluation of SVC-Coupled Hybrid DSTATCOM using JLMS Algorithm for Enhancement of Power Quality

Abstract This research study explains the design and performance of a Static VAR Compensator (SVC) coupled Hybrid Distribution Static Compensator (DSTATCOM) for low voltage power distribution system (PDS). A comparative analysisis done between Voltage Source Inverter (VSI)-based DSTATCOM and SVC Hybrid DSTATCOM using Jordan Least Mean Square (JLMS) algorithm to alleviate the shunt-related power quality (PQ) glitches. The specific design is obtained as compared to the existing neural network toolbox algorithm to improve the estimation speed and accuracy. The main objective is to extract the tuned weighted values of fundamental active and reactive power components of distorted load currents for the switching signal generation using an adaptive JLMS algorithm.Several functions of DSTATCOM and hybrid DSTATCOM using this JLMS controller are showcased for harmonics curtailment, power factor (p.f.) improvement, load balancing, voltage regulation, etc. Simulation results on an SVC Hybrid DSTATCOM have shown an acceptable level of performance under unbalanced loading situations. Finally, some comparative results are provided to validate the feasibility and effectiveness of the suggested topology.

A new quasi-brittle damage model implemented under quasi-static condition using bond-based peridynamics theory for progressive failure

A novel quasi-brittle damage model implemented under quasistatic loading condition using bond-based peridynamics theory for progressive failure is proposed to better predict damage initiation and propagation in solid materials. Since peridynamics equation of motion was invented in dynamic configuration, this paper applies the adaptive dynamic relaxation equation to achieve steady-state in peridynamics formulation. To accurately characterise the progressive failure process in cohesive materials, we incorporate the dynamic equation with the novel damage model for quasi-brittle materials. Computational examples of 2D compressive and tensile problems using the proposed model are presented. This paper presents advancement by incorporating the adaptive dynamic equation approach into a new damage model for quasi-brittle materials. This amalgamation allows for a more accurate representation of the behavior of damaged materials, particularly in static or quasi-static loading situations, bringing the framework closer to reality. This research paves the way for the peridynamics formulation to be employed for a far broader class of loading condition behaviour than it is now able to.

Finite-Set Model Predictive Control for Hybrid Active Power Filter

A finite-set model predictive control (FS-MPC) with coupling capacitor voltage observer scheme is proposed for thyristor-controlled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -coupling hybrid active power filter (TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF) in this article. It ensures the fast transient response, low steady-state error, and good robustness under both inductive and capacitive load situations. Generally, the implementation of FS-MPC for TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF requires sensing of coupling capacitor voltage and thyristor-controlled reactor current in addition to sensing load voltage, load current, and compensation current, which increases the system complexity and cost. To relax this problem, the simplified predictive model is first proposed, thus reducing the required sensing signals and system order. Then, a coupling capacitor voltage observer is utilized to reduce the hardware costs, which can obtain a comparable performance with directly sensed capacitor voltage. The delay compensation is also considered for the control delay in practical realization. Finally, the effectiveness and performance of the FS-MPC with coupling capacitor voltage observer for TC <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -HAPF are verified by simulated and experimental results.

Design and Numerical-Method-Aided Optimization of a Novel Attachment System for Implant-Retained Dental Prostheses Using NiTi Shape Memory Alloys

While nickel-titanium (NiTi) is the primary shape memory alloy (SMA) used in endodontic instruments, restorative dental components so far have not been fabricated from SMAs. The flexibility of these materials may solve problems in implant prosthodontics resulting from non-parallel implant positions and transfer inaccuracies. Based on a prototype of a novel attachment system for implant overdentures, a finite element model was created and used for studying different loading situations and design parameters followed by numerical analysis aided design optimization. The results revealed that the basic design of the attachment is capable of compensating misalignments of supporting implants as well as transfer inaccuracies of a clinically relevant magnitude by accommodating the large deformations induced under masticatory loading upon martensitic phase transformation at almost constant stress. The application of NiTi resulted in the reduction of the reaction forces recorded in the surrounding of the supporting implant, as well, the reaction forces between male and female parts of the attachment system could be reduced which will minimize wear phenomena and subsequent maintenance costs. These effects were seen to be enhanced in the optimized design.

Occlusal load and biomechanics of implant-supported fixed partial dentures: bone stress analysis

Osseointegration emerged in the 1950s, created by Per-Ingvar Branemark, when it was conceptualized as an intimate connection between the implant and the surrounding bone, and with this discovery, it was proposed as a treatment for total or partial edentulism. implants supported. Excessive loads generated by poor adjustment of occlusal forces are recurrent and common, and may generate resorption in the supporting bone; in situations of excess occlusal load, when these loads are distributed at different intensities, on different dental occlusal tables, could this be a reason for the failure of implant-supported rehabilitation? What about the absence of occlusal loading? Could this be a reason for the failure of implant-supported prosthetic rehabilitation? What will be the way to avoid exacerbated stress on occlusal tables, leading to a better generation of treatment prognosis, especially in cases of Fixed Partial Dentures (FPD) with suspended artificial teeth? This study aims, using the finite element methodology, to build a clinical situation of an implant-supported partial denture (FPD) of fixation of 3 elements of regular length, where the location of the occlusal loads (newtons) (total 750N) in the (FPD) ( Fixed Partial Denture) defined in the experimental groups, with higher loads being selected on the occlusal surface of the molar tooth in relation to the premolar, and with different occlusal forces on adjacent teeth, according to an occlusal load proposed in the research. Thus, the occlusal load was distributed, in different intensities, between each tooth of the CAD (Computer Aided Design) model. The biomechanical behavior and stresses of the fragile structures analyzed vary according to the occlusal load exerted and, therefore, controlling such occlusal loads is very relevant. The tensions are always greater and more evident in the posterior regions, whether in the cortical bone or in the medullary bone, especially when occlusal loads are applied unevenly with overload on the posterior elements of the fixed partial denture; therefore, one should always try to preserve these more distal elements.

From Simulations to Accelerated Testing: Design of Experiments for Accelerated Load Testing of a Wind Turbine Drivetrain Based on Aeroelastic Multibody Simulation Data

The trend of increasing the power output and nominal load capacities of wind turbines (WT) over time has been driving the construction of testing facilities with increasing load capacities for testing WT drivetrain components prior to field deployment. Due to the high investment and operational costs of such facilities, a need exists to design accelerated tests that cover load situations corresponding to expected field conditions while maintaining high time-efficiency. This investigation addresses this need by presenting a methodology to achieve the following goals. Firstly, identifying ranges and combinations of WT 6-degree of freedom (6-DOF) rotor loads is to be expected in the field. This is achieved using aeroelastic multibody simulations (MBS) of an MBS WT model being subjected to simulated wind fields covering the design load cases outlined in the IEC 61400-1 standard and by analyzing the simulated time-series data to design accelerated tests that efficiently and realistically cover the design space of the variables, e.g., 6-DOF rotor loads, to be applied during WT drivetrain testing. The designed tests are to take place on a purpose-built test rig that allows for the application and control of the 6-DOF drivetrain input loads and rotational speed. Using the proposed method, accelerated tests were designed that efficiently cover load combinations within the realistic regions of the design space. A comparison with a full factorial design of experiments shows a significant (95+ %) reduction in total test time as well as the ability of the proposed method to help to avoid unsustainable and unrealistic load conditions within the design space that could result in costly, unintended drivetrain failures during testing.

The Peak Stress Method for fatigue lifetime assessment of fillet-welded attachments in steel subjected to variable amplitude in-phase multiaxial local stresses

The Peak Stress Method (PSM) for the fatigue strength assessment of welded joints has been recently generalised to account also for variable amplitude (VA) multiaxial loading situations. In the present study, the previously published VA PSM has been verified against new experimental results generated by fatigue testing non-load-carrying (nlc) fillet-welded double transverse or inclined attachments made of S355 structural steel subjected to variable amplitude in-phase multiaxial local stresses. Combined with Miner’s Linear Damage Rule (LDR), the PSM proved effective in predicting the crack initiation location and accurate in estimating the experimental fatigue results.

Influence of R-Ratio on Fatigue of Aluminum Bonding Wires

Bonding wires made of aluminum are the most used materials for the transmission of electrical signals in power electronic devices. During operation, different cyclic mechanical and thermal stresses can lead to fatigue loads and a failure of the bonding wires. A prediction or prevention of the wire failure is not yet possible by design for all cases. The following work presents meaningful fatigue tests in small wire dimensions and investigates the influence of the R-ratio on the lifetime of two different aluminum wires with a diameter of 300 µm each. The experiments show very reproducible fatigue results with ductile failure behavior. The endurable stress amplitude decreases linearly with an increasing stress ratio, which can be displayed by a Smith diagram, even though the applied maximum stresses exceed the initial yield stresses determined by tensile tests. A scaling of the fatigue results by the tensile strength indicates that the fatigue level is significantly influenced by the strength of the material. Due to the very consistent findings, the development of a generalized fatigue model for predicting the lifetime of bonding wires with an arbitrary loading situation seems to be possible and will be further investigated.

Validation of 2D Force Measurement Roller Ski and Practical Application.

Several methods could be used to measure the forces from skis or roller skis in cross-country skiing. Equipment that could measure medio-lateral forces may be of good help for investigating the relevant skating techniques. The aim of this study was to validate a pair of newly designed two-dimensional force measurement roller skis. The vertical and medio-lateral forces which were perpendicular to the body of the roller ski could be measured. Forces were resolved into the global coordinate system and compared with the force components measured by a force plate. A static and dynamic loading situation for the force measurement roller ski was performed to reveal the validity of the system. To demonstrate whether the force measurement roller ski would affect roller skiing performance on a treadmill, a maximum speed test with the V2 technique was performed by using both normal and force measurement roller skis. The force-time curves obtained by these two different force measurement systems were shown to have high similarity (coefficient of multiple correlations > 0.940). The absolute difference for the forces in the X and Z directions over one push-off cycle was 3.9−33.3 N. The extra weight (333 g) of the force measurement roller ski did not affect the performance of the skiers. Overall, the newly designed two-dimensional force measurement roller ski in this study is valid for use in future research during daily training for skate skiing techniques.

Transformer-Less Novel Hybrid Converter Based Solar PV fed UPS System

The uninterrupted power supply (UPS) plays a dominant role in domestic appliances and also the growth rate of solar roof top system implementation is massively increasing day by day. To minimize the cost on the converters, solar PV power is directly connected with existing UPS with separate MPPT controller. However, due to the presence of nominal frequency transformer, the size and cost of UPS becomes more. In addition, it consumes the power with poor power quality to charge the battery. Apart this, the current supplied from the battery is much higher due to the lower voltage level of battery, which makes voltage dip during peak load condition and resulting to shorten the battery life and degrades its performances. In order to overcome all these drawbacks, this particular paper proposes a transformer-less novel hybrid converter based solar PV fed UPS system. In the hybrid structure, the gain can be achieved higher with minimum components counts. The novelty of the proposed transformer-less hybrid converter is that the regeneration of switched capacitor voltage is applied to input of switched inductor network in DC–DC converter, due to this hybrid structure the gain has been extended drastically with minimum number of devices. Also the coordinated control algorithm is implemented in solar PV fed UPS to take the decision according to the situation of generation, load and battery back-up. The detailed operation of the proposed coordinated control algorithm has been addressed in this paper. Moreover, the detailed simulation study is carried out for each mode of operation and measured results are obtained and presented in this paper.