bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conjugate Mixed Convection in a Differentially Heated Lid-Driven Square Cavity With Rotating Cylinders
Authors: Paul Durjoy Kumar , Al Mehedi Abdullah , Chowdhury Emdadul Haque , Saha Sumon , Ali Mohammad , Amin M. Ruhul 
Published: February 2021

Abstract
Conjugate mixed convection in a lid-driven differentially heated square cavity with two heat-conducting rotating cylinders is numerically investigated. The right and the left walls of the enclosure, respectively, are maintained at a constant higher temperature (Th) and lower temperature (Tc), keeping the horizontal walls adiabatic. Both the cylinders are rotating in the counterclockwise direction. Only the left wall is moving downwards with a constant velocity. The governing nondimensional partial differential equations are resolved by means of Galerkin weighted residual finite element formulation. The average Nusselt number (Nu) is calculated along the right vertical heated wall. Flow and thermal fields are presented via streamlines and isotherms. Parametric simulations are performed for various pertinent parameters which are Grashof number (Gr), Reynolds number based on lid velocity (Re), Reynolds number based on cylinders’ peripheral velocity (Rec), and Richardson number (Ri). At first, the effects of variation of cylinders’ diameter are observed by considering six different cases for a particular peripheral velocity. It is found that the maximum Nu is obtained when the diameters of both cylinders are 0.1L. Further simulation is done for varying the Rec in the range of 5 to 50, to observe the effect of cylinders’ rotational speed. It has been found that for a particular Re, Nu increases with increasing rotational speed, but the effect is more pronounced at low Re. Finally, the combined effects of both Re and Gr on Nu have been investigated, keeping the Ri in the laminar mixed convection region. It has been demonstrated that when the Ri is increased from 0.1 to 10, the Nu enhances about 395.7%.
Assessment of Weld Bead Performance for Pulsed Gas Metal Arc Welding (P-GMAW) Using Acoustic Emission (AE) and Machine Vision (MV) Signals Through NDT Methods for SS 304 Material
Authors: Addamani Rudreshi , Ravindra Holalu Venkatdas , Gayathri Devi S. K. , Gonchikar Ugrasen 
Published: February 2021

Abstract
To gain high cost effective products along with quality and productivity, Pulsed Gas Metal Arc Welding (P-GMAW) process is used in many highly developed industries for fabrication of welded joints. The input parameters are the most important factors which affects the productivity, quality and cost effective for the welding process. The processes enable low net heat input, stable spray transfer and with low mean current. To enhance efficiencies with constant voltage GMAW process, P-GMAW is an outstanding substitute for those industries which are looking to improve quality of welds since the process helps over varying operator’s skills. It is essential to determine the input/output relationship parameters, in order to recognize and control the P-GMAW welding process. P-GMAW applies waveform control logic to fabricate a very precise control of the arc during speed range and a broad wire feed.
The power source switches between low background current and a high peak current between 30 to 400 times per second to obtain modified spray transfer process. The peak current pinches off wire droplets and drive it to the welded joints over this period. The process produces low heat input allowing weld pool to solidify, that metal transfer cannot occur but by the mean time, background current maintains the arc with stable spray transfer.
Trials have been conducted on SS 304 material using copper coated filler wire of size 1.4 mm based on the Taguchi’s L27 standard orthogonal array. Current, Gas Flow Rate (GFR) and Wire Feed Rate (WFR) with a constant speed are the input parameters considered to carry out trials. The output parameters are Yield strength (YS, N/mm2), percentage of elongation and Ultimate Tensile Strength (UTS, N/mm2). Indirect response parameters are Viz., AE signals such as welding AERMS, welding AEENERGY, tensile AERMS and tensile AEENERGY along with MV signals like area and height of the weld bead are considered to assess the performance of the weld bead joint. It is clearly observed from the obtained results that an excellent relationship exists between welding AERMS welding AEENERGY with tensile AERMS and tensile AEENERGY along with MV signals which were taken at the time of tensile test to evaluate the performance of the weld bead joint.
Verification of the results are carried out through performing different NDT testing methods on weld bead joint Viz., X–radiography, Scanning Electron Microscope (SEM) images to analyse external defects in the welded joints. On different zones of welded joint, Energy dispersive analysis (EDX) examination is carried out for elemental composition.
Experiment Study on the Current Density Distribution of PEMFC by Segmented Cell Technology
Authors: Miao Tianwei , Xie Xu , Tongsh Chasen , Liang Jinqiao , Liang Yiqi , Liu Zhi , Du Qing , Bai Fuqiang , Jiao Kui 
Published: February 2021

Abstract
The homogeneous of current density distribution is very important for performance and lifetime of proton exchange membrane fuel cell. In this study the current density distribution of a fuel cell with an active area of 108 cm2 has been investigated by using segmented cell technology. The σc is introduced to evaluate the homogeneity of current density and the smaller value of σc represents better homogeneity of current distribution. Under normal conditions, the experimental results show that the current density decreases progressively along the flow field at low cathode stoichiometry. It is also found that the homogeneity of current distribution has a strong correlation with the membrane hydration condition and always performs best at cathode relative humidity of 80% when anode condition keeps constant. The value of σc can be significantly reduced when cathode stoichiometry increases from 1.5 to 2.5, but it changes little when cathode stoichiometry continues to increase. During the cold start process, the evolutions of current density distribution are consistent with the temperature mappings. The form of stabilized heat core in the middle regions and homogeneous current density distribution are necessary for successful cold start. The value of σc also can be used to evaluate that the cold start succeeds or not.
Simulation and Visualization of Dynamic Systems in Virtual Reality Using SolidWorks, MATLAB/Simulink, and Unity
Authors: Akharas Ismail , Hennessey Michael P. , Tornoe Eric J. 
Published: February 2021

Abstract
This paper introduces a novel method for playing dynamic animations of rigid body assemblies with internal motions in virtual reality (VR). Through previous research over a decade ago, an inexpensive, relatively straight-forward process has been developed that entailed using SolidWorks, MATLAB/Simulink, and movie player software to permit one to view 2D MP4 files, such as on a laptop, smart phone, etc. Inspired by the usefulness of these previous results, the approach presented here targets a VR environment, clearly representing a technological leap over viewing 2D MP4 files. It’s made possible by recent advances in VR & gaming software (e.g. Unity) along with some unique software interfacing, including use of CADLink, to permit importation of CAD files, such as from SolidWorks, into Unity. Those interested in VR visualization of their dynamic system can use the step-by-step process presented as a manual to guide them through the hardware and software setup and ultimately learn how to use SolidWorks, MATLAB/Simulink, and Unity interactively to visualize their simulations in VR. Another key point is that the analyst has considerable control and access over each step in the process, including the dynamic modeling, unlike that commonly found in large, structured dynamic simulation software packages.
As an example to illustrate the process, a dynamic simulation of a classic pendulum/slider system was created using MATLAB/Simulink, which in effect numerically solves the ordinary differential equations of motion. The time-dependent displacement data for both the slider’s lateral movement and the pendulum’s angle, along with a time vector in incremental difference form, was saved as an Excel file. In turn, it was read by a C# script residing within Unity to permit an animation playback scenario of the SolidWorks CAD model of the entire pendulum/slider system (previously brought into Unity via CADLink with some reassembly), viewed more generally as an assembly with internal motions. Unity, a popular open-source piece of VR game development software used to produce both 2D and 3D video games and simulations, then serves as a platform to access the virtual world with the aid of an Oculus Rift (or Quest) VR headset and two hand controllers. In the end, the VR viewer can physically move around in the VR environment while at the same time view the playback motion of the pendulum/slider system from varying vantage points, just as one would expect in the real world. This work significantly advances the typical visualization experience with respect to dynamic system simulation & animation in addition to being widely applicable to generic mechanical assemblies.
Analysis and Design of an Auxiliary Catching Arm for an Apple Picking Robot
Authors: Porter Andrew , Alhamid Jassim , Mo Changki , Miller John , Iannelli Joseph , Honegger Marcel , Lichtensteiger Lukas 
Published: February 2021

Abstract
The newly designed 3-dimensional catching robot consists of three revolute joints where the forward linkage is a parallelogram mechanism for keeping the catching end-effector parallel to the picking manipulator’s base. A virtual apple field of 505 apples, designed to test the picking abilities of 7 DOF arm, was used to determine the capabilities of this new catching arm design. The target catching efficiency was 90% for the provided virtual apple field with a maximum drop height of 30 cm. The target coordinates for each virtual apple were found by computer simulation in MATLAB. Geometric parameters were selected such that the catching manipulator could reach every possible drop position in the picking manipulator’s workspace. The design was completed, fabricated, and validated, utilizing the elegant mechanical linkage design. The workspace analysis showed that it had an acceptable 93% catching efficiency, and as the drop height increased, the efficiency approaches 100%. Definitive inverse-kinematics provided exact joint angles required to catch all catchable apples inside of the workspace. Using these angles, the general equation of motion, using Lagrangian mechanics, yielded the required torque outputs of each of the three motors on the arm. Validation of these torques through laboratory experimentation was considered adequate.
Thermomechanical Formulation of Freezing Point Depression Behavior of Liquid on Solid Surface With Nanostructure
Authors: Hanawa Y. , Sasaki Y. , Uchida S. , Funayoshi T. , Otsuji M. , Takahashi H. , Sakuma A. 
Published: February 2021

Abstract
In this study, we investigated the freezing point depression of liquids in nanostructures using a new thermomechanical method. First, we experimentally determined the freezing points of water, cyclohexane, and a certain organic material (Chem.A) in nanoscale structures using DSC measurements. Thereafter, we formulated a new equation by improving the Gibbs–Thomson equation, which is the conventional formula for representing the freezing point depression of a liquid in nanostructures. We introduced a new term in this new equation to represent the increase in the kinetic energy of the liquid molecule as a result of collision between the liquid molecules and nanostructure walls. Subsequently, we evaluated the solid–liquid interface free energy of sublimation materials by fitting the theoretical freezing point derived from the new equation to experimental data. In this study, we succeeded in reproducing the experimental data of freezing point depression using the proposed equation. In particular, the freezing points of cyclohexane and Chem.A in the nanostructure were better fitted by this new equation at 10 nm or more compared with the conventional equation. Our results show that the interaction between the wall of the nanostructure and liquid molecules affects freezing point depression.
Efficient Spot Welding Sequence Simulation in Compliant Variation Simulation
Authors: Sadeghi Tabar Roham , Lorin Samuel , Cromvik Christoffer , Lindkvist Lars , Wärmefjord Kristina , Söderberg Rikard 
Published: February 2021

Abstract
Geometric variation is one of the sources of quality issues in a product. Spot welding is an operation that impacts the final geometric variation of a sheet metal assembly considerably. Evaluating the outcome of the assembly, considering the existing geometrical variation between the components can be achieved using the Method of Influence Coefficients (MIC), based on the Finite Element Method (FEM). The sequence, with which the spot welding operation is performed, influences the final geometric deformations of the assembly. Finding the optimal sequence that results in the minimum geometric deformation is a combinatorial problem that is experimentally and computationally expensive. For an assembly with N number of welds, there are N! possible sequences to perform the spot welding operation. Traditionally, spot welding optimization strategies have been to simulate the geometric variation of the spot-welded assembly after the assembly has been positioned in an inspection fixture, using an appropriate measure of variation. In this approach, the calculation of deformation after springback is one of the most time-consuming steps. In this paper, the cause of variation in the deformations after the springback, between different sequences is identified. The relative displacements of the weld points in the assembly fixture, when welded in a sequence, is the source of such behavior. Capturing these displacements leads to large time savings during sequence optimization. Moreover, this approach is independent of the inspection fixture.
The relative weld displacements have been evaluated on two sheet metal assemblies. The sequence optimization problem has been solved for the two assemblies using this approach. The optimal sequence, the corresponding final assembly deformations, and the time-consumption have been compared to the traditional approach. The results show a significant correlation between the weld relative displacements in the assembly fixture, and the assembly deformation in the inspection fixture. Considering the relative weld displacement makes each assembly evaluation less time-consuming, and thereby, sequence optimization time can be reduced up to 30%, compared to the traditional approach.
Design of a Compliant Based Biomimetic Planar Locomotive Mechanism
Authors: Loupe Dillon , Kim Hanseul , Tekes Ayse , Tekes Coskun , Ali Amiri Moghadam Amir 
Published: February 2021

Abstract
This paper presents the design, development, modeling and control of a biomimetic multi degree of freedom compliant locomotive mechanism that can follow a prescribed trajectory. The research objective of this study is the design of a high mobility and flexible planar locomotive mechanism incorporating large deflecting compliant hinges. The actuation is realized using servo motors. Mechanism is consisted of five sliding carts, rail, 3D-printed supplementary pieces to house motors and pins. Carts are connected by monolithically designed two arm links joined by a large deflecting flexure. Four servo motors are mounted on the driven carts. Since sliding carts are identical, forward motion is achieved by changing the friction of carts through the connecting pins. Dynamical model is created in Matlab Simulink using Euler’s laws of motion principle, pseudo rigid body modeling (PRBM), vector closure-loop equations and kinematic constraints. To robustly control the position of the mechanism, first its nonlinear dynamics replaced with a family of linear time invariant systems which have parameter uncertainty. Then a robust controller is designed based on the Quantitative Feedback Theory (QFT) for the desired robust tracking and stability bounds. QFT is one of the most powerful robust control techniques which can take into account both phase and magnitude information of the system and enables the designer to minimize the cost of feedback by clearly observing the design constraints through robust performance bounds. Finally, the performance of the designed controller is validated though nonlinear simulations using the nonlinear dynamics of the mechanism. It has been shown that the mechanism can consistently track the desired inputs both in frequency and time domains.
RPM-Synchronous Grinding: An Innovative and Efficient Manufacturing Method for the Production of Non-Circular Workpieces
Authors: Spenger Thomas , Haas Franz , Pichler Jonas , Weinzerl Martin , Eder Stefan J. , Weiß Markus 
Published: February 2021

Abstract
RPM-Synchronous Grinding (RSG) opens up a wide range of applications, as this manufacturing process enables the efficient production of components with a functional macro geometry as well as a functional micro geometry of the surface. Unlike conventional non-circular grinding approaches, the RSG process strategy requires no oscillation of the infeed axis of the grinding spindle generated by coupling the rotation with the workpiece spindle. By using a fixed ratio of grinding wheel and workpiece spindle speed in conjunction with a non-circular grinding wheel geometry, almost all workpiece macro geometries can be produced in a simple plunge grinding process. The topology of the grinding wheel, the kinematic parameters of the dressing and grinding process and the material parameters of the workpiece must be sensibly matched to each other for an advantageous application of the process. Experiments can help to identify relationships, but simulation tools are needed to derive general predictions. Therefore, Molecular Dynamics Simulation (MD) is used to analyze the material removal process. By considering synchronous grinding at this level, the microstructural development of the workpiece and the chip formation process follow directly from atomic interactions, thus yielding elementary relationships to describe grinding. In the presented application, a defined cam geometry for an established steel material is produced using a conventional vitrified grinding wheel in the RSG process. The surface quality and geometric accuracy of the manufactured workpieces are evaluated. A selection of the MD grinding simulation results (workpiece, abrasive, and their interactions) is presented, and their intended application to the grinding process is discussed.
The Condensation Heat Transfer Characteristics of Zeotropic Hydrocarbon Mixtures in a Helical Pipe
Authors: Li Shulei , Zhu Rui , Xie Gongnan , Jiang Yiqiang , Cai Weihua 
Published: February 2021

Abstract
In order to explore tube-side heat transfer characteristics in the spiral wound heat exchange (SWHE) used in liquid natural gas (LNG) plants, the study on zeotropic hydrocarbon mixtures condensation heat transfer in a helical pipe is proposed. Firstly, based on two-fluid model and thermal phase change model, a numerical method coupling with empirical correlations is established to predict condensation heat transfer for zeotropic mixtures, in which the mixed effects are taken into account. Meanwhile, the rationality of the above methods is verified based on existing experimental results. Then, the effects of refrigerant components and operating parameters on flow patterns, heat transfer coefficients and heat and mass transfer resistance are discussed as the ranges of mass flux, saturation pressure and vapor quality are 200–800 kg/(m2·s), 2–4MPa and 0.15–0.90, respectively. It can be found that the predicted results coincide with the experimental ones, with deviations within ±15%. For different zeotropic hydrocarbon mixtures, as the vapor quality increases, the stratified flow, half-annular flow and annular flow appears in turn. The condensation heat transfer coefficients are always smaller than film heat transfer coefficients owing to the existence of heat and mass transfer resistance in vapor core. Besides, both film and condensation heat transfer coefficients increase with the increase of vapor quality and mass flux, while decrease with the rise in saturation pressure. Further, heat and mass transfer resistances increase as the vapor quality and saturation pressure increase and the mass flux decreases. In addition, compared to methane/ethane/propane/nitrogen (65/25/5/5, mole%) mixture, the averaged heat transfer performance for methane/ethane (90/10, mole%) mixture improves by 19.55%, whereas, the average heat and mass transfer resistance decreases by 53.51%. This study is helpful for understanding the zeotropic mixtures condensation in tubes and gives some suggestions for the choice of refrigerant components used in LNG SWHE, to design more effective SWHE.
Reflector-Augmented Photovoltaic Power Output Incorporating Temperature-Dependent Photovoltaic Efficiency
Authors: Alasadi Habeeb , Mulford Rydge , Gilbert Robert 
Published: February 2021

Abstract
The power output produced by Photovoltaic (PV) panels depends on the quantity of solar energy incident on the PV surface, the surface area of the module and the efficiency of the system which is a function of the module’s surface temperature. Concentration of solar irradiation onto a PV surface augments the solar energy flux on the module surface as has been shown by published literature. However, concentrated solar irradiation increases the PV surface temperature, decreasing the efficiency of the module. The papers presented in the literature review do not exam the impact of PV models temperature on performance of PV efficiency. In this work, the influence of temperature-dependent module efficiency on the power extracted from a Reflector-Augmented Photovoltaic (PV) module is explored. A reflector-collector system is considered theoretically having a variable angle between the reflector and collector as well as a variable angle between the reflector and the horizontal axis. The hourly solar radiation incident on the PV module and the reflector are obtained using TMY3 data of Dayton. The total solar radiation (direct and reflected components) striking the collector is calculated on an hourly basis which is in turn used to determine the temperature of the PV module. The electrical power produced on an hourly basis is then calculated in Dayton, OH. In order to determine the influence of temperature-dependent PV efficiency on system behavior, this study determines the electrical power produced by the system for two separate cases: a constant PV efficiency (which does not vary with temperature) as well as a temperature-dependent PV efficiency. For both cases, four separate conditions are evaluated, being different combinations of reflector-collector angle as well as reflector-horizontal angle. Results indicate that the output power of a PV module with temperature-dependent efficiency is less than the output power of the same PV module having a constant efficiency. Monthly average power increase fractions variation of both cases follows a similar trend while power increase fractions are higher during summer times than winter times. Temperature-independent power increase fractions are also higher on average than temperature-dependent power increase fractions for all four conditions.