bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Transition From Regular to Mach Reflection Over a Moving Wedge
Authors: Margha Lubna , Hamada Ahmed A. , Knight Doyle D. , Eltaweel Ahmed 
Published: January 2022

Abstract
The transition between the Regular Reflection (RR) and Mach Reflection (MR) phenomenon impacts the design of the supersonic and hypersonic air-breathing vehicles. The aim of this paper is to numerically investigate the dynamic transition from RR to MR of unsteady supersonic flow over a two-dimensional wedge, whose trailing edge moves along the x-direction upstream with a velocity, V(t) at a free-stream Mach number of M∞ = 3. The simulation is conducted using the unsteady compressible inviscid flow solver, which is implemented in OpenFOAM®, the open-source CFD tool. Further, the wedge motion is applied by moving the mesh boundary, performing the Arbitrary Lagrangian-Eulerian (ALE) technique. In addition, the sonic and the detachment criteria are used to define the dynamic transition from RR to MR during the increase of the wedge angle. Different reduced frequencies, κ, in the range of [0.1–2] for the moving wedge are applied to study the lag in the dynamic transition from the steady-state condition. The results show that the critical value of κ = 0.4 distinguishes between the rapid and gradual lag in the transition from RR to MR. In addition, the transition from RR to MR occurs above the Dual Solution Domain (DSD), since the shock is curved downstream during the rapid motion of the wedge.
Algorithm to Avoid Normal Tissue Sacrifice and Thermal Injury of Neighbouring Organs During Radiofrequency Ablation of HCC Tumours Treated Using a Multi-Tine Electrode With Separately Controlled Tines
Authors: Dhiman Manoj , Repaka Ramjee 
Published: January 2022

Abstract
Radiofrequency ablation of Hepatocellular Carcinomas lacks electrode level feature to (a) avoid the risk of thermal injury to the neighbouring organs and (b) avoid the sacrifice of normal hepatic tissue. The absence of such a feature causes additional intrusion of the human body to overcome the first problem, while there is no solution for the latter problem. An algorithm has been developed and implemented using an unconventional multi-tine RFA electrode to incur ablations specific to the shape and position of target tumours to solve these problems. Further, this algorithm can suggest the best insertion angle for the trocar, such that minimum normal tissue is sacrificed. This suggestion is made quickly with the help of a pre-simulated database. For verification of the algorithm, pre-segmented tumours have been used as inputs and damages incurred with and without algorithm have been compared.
Effect of Process Parameters on the Microstructure of Closed-Open Cross Wedge Rolling
Authors: Shu Xuedao , Wang Jitai , Han Sutao , Wei Yilun 
Published: January 2022

Abstract
Microstructure is one of the key factors determining the mechanical properties of an axle, which requires to obtain fine and uniform grain structure. This research work aims to explore the influence of different process parameters on the average grain size and distribution uniformity of the rolled piece during the closed-open cross wedge rolling (CWR) process, so as to improve the micro quality of the rolled piece by adjusting the process parameters. Firstly, an automobile oil pump axle made of 42Crmo is considered as a research object, and a 3D thermal-mechanical-microstructure coupled finite element model of closed-open CWR is established by adopting software DEFORM. Secondly, three points are uniformly selected along the central axis of the rolled piece as observation points, and the variation law of the average grain size at different positions with time is studied. Thirdly, the effects of the reduction of area, the diameter of the rolled piece, the forming angle of the wedge section and the stretching section on the average grain size of the rolled piece and the uniformity of the grain distribution are studied separately. Finally, combined with the closed-open CWR experiment, the influence of different billet diameter on the average grain size is consistent with the simulation results, which verifies the reliability of the model.
Performance Analysis of Zeotropic Organic Rankine Cycle for Marine Diesel Exhaust Heat Recovery
Authors: Gao Qizhi , Yuan Han 
Published: January 2022

Abstract
Marine diesel engine plays the dominate role on the merchant ship power supply field, which is responsible for 3.1% of global CO2 emissions. As one third of the energy is wasted along with the exhaust gas, heat recovery of marine diesel exhaust is an effective way of improving the thermal efficiency of entire power system. The temperature of marine diesel exhaust ranges from 250°C to 550°C, and this medium/low-grade heat source can be recovered by thermodynamic cycle technology. The Organic Rankine Cycle (ORC) is most commonly used in medium/low-grade waste heat recovery because of its simple structure. However, ORC utilizes the pure organic compound as the working fluid, and the evaporation of the pure organic compound experiences with isothermal and isobaric process, resulting in a relatively high temperature difference of heat transfer between the heating source and working fluid, which ultimately limits the thermal efficiency of ORC. In comparison, the Zeotropic Organic Rankine Cycle (ZORC), which utilizes the zeotropic mixture and working fluid, is proved competitive for the temperature slip phenomenon in its evaporation process. Besides, the heat transfer in the condenser will get worse due to the liquid accumulating on the condensation wall, leading to a larger heat exchange area requirement. Therefore, the liquid-separation condensation method is investigated to reduce the heat exchange area of condenser. In this study, both the multi-pressure evaporation and liquid-separation condensation processes are introduced to improve the ZORC performance. Working fluid selection for the ORC and ZORC with a wide range of marine diesel exhaust temperature is conducted, with corresponding evaporation temperature ranges between 100°C and 200°C. The proportion analysis for different kinds of zeotropic organic mixture is made to obtain the optimized working fluid under the given evaporation temperature by 200°C. Cyclopentane-toluene (0.55–0.45) can reach the highest efficiency with 19.76%. Moreover, thermodynamic analysis based on the first law and second law of thermodynamics are made to reveal the thermal efficiency, output work and exergy efficiency of these cycle, as well as the exergy destruction in each component. In addition, the dryness of mixture at the liquid-separation point in the condensation process, which reveals the position of the liquid-separation outlet in the condenser, is discussed. The results show that the major exergy destruction occur in the evaporation and condensation processes. With the assistance of multi-pressure evaporation and liquid-separation condensation processes, the exergy destruction in the heat exchangers is decreased by 17.09%∼21.61%.
Study on the Operation Strategy Based on Multi-Objective Optimization Considering Power and Emission Performance for a Gas Turbine
Authors: Li Bei , Chen Jinwei , Zhang Huisheng 
Published: January 2022

Abstract
The control strategy of a gas turbine is usually to maintain the turbine outlet temperature by adjustable inlet guide vane (IGV), thereby ensuring that the gas turbine operates in an efficient region, however, this method is difficult to optimize the power and emission performance simultaneously for the gas turbine at a specific operating power. In this study, a thermodynamic model suitable for the gas turbine dynamic performance and a NOx emission model based on least squares support vector machine are established, then the relationship between gas turbine thermal efficiency, emission and state trajectories is determined by a gas turbine multi-objective optimization method. The optimization framework adopts multi-objective particle swarm optimization algorithm, targeting efficiency and NOx emission, using operating power as a constraint to make the multi-objective analysis of the gas turbine operation process, which provides guidance for the development of multi-objective optimization control strategies for gas turbines.
Effect of Particle Overlapping Impacts in Erosion Process
Authors: Zang Xuerui , Cao Xuewen , Xie Zhenqiang , Zhang Jun , Li Yijie 
Published: January 2022

Abstract
To improve the accuracy of the erosion prediction, it is necessary to consider the influences of adjacent particles in the calculations. Therefore, in the present work Johnson-Cook hardening criterion and Johnson-Cook damage criterion are used in ABAQUS software to study erosion crater morphology and stress distribution on target materials subjected to overlapping impacts of spherical particles. The results show that the impact location of the adjacent particles, which is defined as the horizontal distance between the solid particle impacting spot, can significantly affect the erosion magnitude and pattern. As the horizontal distance between two impacts increases from 0 to 0.6 times the particle diameter, the interaction of the craters gradually decreases. When the horizontal distance is beyond 0.6 times the particle diameter, the interaction between two craters is disappeared. Furthermore, the depth difference between two craters is increased under the impact of adjacent particles. As the impact velocity increases from 14 m/s to 22 m/s, the difference between the depth of two craters is increased from 3.23 μm to 14.7 μm. When the impact angle increases from 25° to 85°, the depth difference between the two craters is increased from 0.11 μm to 14.40 μm. The numerical simulation of erosion process can provide a scientific basis for more elaborate erosion modeling.
A Numerical Study on Effect of Tool Roller Rotation on Channel Springback
Authors: Nikhare Chetan P. 
Published: January 2022

Abstract
The current work is an extension of the work published at IMECE2020. The study presents the innovative patented technique to reduce the springback in channel deformation. Springback is one of the common defects in sheet metal forming and is a constant research area due to continuous push on lightweight to decrease the fuel consumption and decrease the environmental impact. To follow the federal environmental guidelines the option is either use the lower density material or use the lower gages of advance high strength materials. In both cases springback will be an issue as the lower density material will be having lower modulus of elasticity and even the elastic values are higher in the higher strength material, with respect to strength the elastic recovery increases. With these many challenges with the materials and their properties which influences the springback, other possible innovative forming processes are applying electricity through the material after forming and before the release of the load, performing warm or hot forming, die compensation, etc. One such innovative and patented process which is studied in the paper is using rollers in the tool i.e., in die and punch during the forming process. During the channel deformation process the punch and die rollers rotate with a given rotations. The rollers are also set to rotate in either clockwise or counterclockwise direction. In IMECE2020 the work was published on considering the single roller rotation value in all cases i.e., from Case3 to 10. In this paper, four more roller rotations were studied to see the effect of tool roller rotation on the springback. The process was simulated in ABAQUS finite element software. The springback profile, springback angle and stresses in the channel were studied. It was found that with increasing the roller rotations the springback decreases.
Experimental Study of Gas-Liquid Displacement in a Porous Media Microchip by Digital Image Analysis Method
Authors: Yang Shuo , Kong Gaopan , Wu Zan 
Published: January 2022

Abstract
Gas-liquid displacement is still a complex and challenging topic in the field of nonequilibrium physics and many industrial applications. In this study, pore-scale displacement of gas-liquid flow in a porous medium was investigated. A digital image analysis method was used to process the images captured by a high-speed camera. The invasion pattern demonstrated that an increase in viscosity of the displaced liquid tends to decrease the finger width and the number of fingers. The effect of liquid viscosity on the invasion velocity was also investigated. The invasion velocity changes monotonously with the viscosity, showing an opposite trend at high and low gas flow rates, which is attributed to the viscous resistance of the liquid phase and the mass balance of the gas phase. Then the invasion area was measured and the N2 displacement ratio was used to estimate the injection efficiency. The displacement ratio decreases with the increase of liquid viscosity and gas flow rate. Finally, the invasion dynamics was studied. It revealed that the gas tip moves in a stepwise way, i.e., the tip goes forward, and then it stays there for a while and then goes forward again. The gas tip splits and expands in side directions and also moves backward when the gas pressure is not high enough to overcome the forward capillary pressure, which can be found for all the displaced liquids in this study.
Generation and Parameterization of Forced Isotropic Turbulent Flow Using Autoencoders and Generative Adversarial Networks
Authors: Kanishk  , Nandal Tanishk , Tyagi Prince , Singh Raj Kumar 
Published: January 2022

Abstract
Autoencoders and generative neural network models have recently gained popularity in fluid mechanics due to their spontaneity and low processing time instead of high fidelity CFD simulations. Auto encoders are used as model order reduction tools in applications of fluid mechanics by compressing input high-dimensional data using an encoder to map the input space into a lower-dimensional latent space. Whereas, generative models such as Variational Auto-encoders (VAEs) and Generative Adversarial Networks (GANs) are proving to be effective in generating solutions to chaotic models with high ‘randomness’ such as turbulent flows. In this study, forced isotropic turbulence flow is generated by parameterizing into some basic statistical characteristics. The models trained on pre-simulated data from dependencies on these characteristics and the flow generation is then affected by varying these parameters. The latent vectors pushed along the generator models like the decoders and generators contain independent entries which can be used to create different outputs with similar properties. The use of neural network-based architecture removes the need for dependency on the classical mesh-based Navier-Stoke equation estimation which is prominent in many CFD softwares.
Developing HVAC System Terminal Units Control Sequence Utilizing Game Theory Rules
Authors: Khazaii Javad , Khazaei Ali 
Published: January 2022

Abstract
Human thermal comfort depends on multiple factors such as temperature, humidity ratio, air velocity, metabolism etc. Two of the most important of these parameters that are being controlled simultaneously via air conditioning system in spaces are temperature and humidity ratio. Achieving thermal comfort in multi-occupancy spaces occupied with people with different levels of acceptable thermal comfort not only can help creating more desirable experience for majority of the occupants in these spaces, but also can save energy by optimizing the operation of the air conditioning system and avoiding unnecessary energy consumption when there is no need for controlling temperature and humidity at pre-selected values. Meanwhile, research shows current measures of thermal comfort are at best 30–40% accurate, since they have been developed decades ago and based on the desired references of a specific group of people in that time. Space control algorithms that are generally written to hold temperature and humidity ratio based on a typical human response to parameters affecting thermal comfort should be customized to provide the optimum comfort level for people with different thermal comfort preferences occupying the same offices or spaces. Such optimization can be achieved via utilizing rules of game theory — which is a strategic method of decision making among competing or cooperating decision makers — to help finding the best combination of the temperature and humidity ratio. This helps to create thermal comfort for different combinations of occupants in the space with different thermal comfort preference. This work represents a new way of writing sequence of controls for air handling units, to maximize thermal comfort of all the occupants and at the same time creates opportunity for saving energy by avoiding single set-point for delivering air temperature and humidity ratio.
Cascade Utilization of Geothermal Waste Heat for Enhanced Outdoor Crop Production
Authors: Mignano Christopher , Dushaj Enea , Unnthorsson Rúnar , Dell Robert 
Published: January 2022

Abstract
Iceland’s harsh climate limits the number of harvestable cultivars that can be grown outdoors. While Icelandic heated greenhouses enable a larger variety of crops to be grown, their upkeep is labor and resource intensive, and the associated costs can be prohibitive. Professor Robert Dell, Director of the Laboratory for Energy Reclamation and Innovation (LERI) at the Cooper Union has developed an intensive cascade utilization system using waste steam condensate and hot water as a working fluid that creates an outdoor shallow network of plastic pipes for heating garden soil. This research and development, which began in 2007 in New York City and 2009 in Iceland, compares plant growth between heated and control gardens. Previous studies’ test beds used municipal district heated wastewater, waste fluid from a geothermal heated swimming pool, and waste hot water from a traditional heated greenhouse. This paper analyzes the results of enhanced outdoor crop production using a new small-scale, high yield garden from the 2019 growing season at the Agricultural University of Iceland (Landbúnaðarháskóli Islands). The plants studied include turnips, zucchinis, tomatoes, oregano, and a variety of peppers. A plant growth index was developed for analytical purposes. It takes the weighted average of measurements of plant height and the two widest stem spread diameters to quantify growth before the harvest. The plants in heated gardens grew approximately 45% taller and wider on average than those in unheated beds.
Experimental Investigation of Multi-Component Emulsion Fuel Stability
Authors: Hentges Nicholas , Parveg A. S. M. Sazzad , Ratner Albert 
Published: January 2022

Abstract
The emulsification of water with liquid fuels to modify combustion characteristics has been of great interest to the combustion research community for some time. The emulsions are usually comprised of only water combined via ultrasonification (or other mechanical methods) with a base hydrocarbon fuel. These emulsions show improved combustion characteristics, such as lower combustion temperatures, and lower emissions. One of the main issues with these emulsions, however, is that these emulsions are not stable and are prone to phase separation over time, which inhibit the economic viability and practical application of these fuels. There are a multitude of ways being researched to improve fluid stability, including new mixing techniques, the addition of nanoparticles, as well as the addition of other fluids. The addition of ethanol to water-based emulsions has been shown to decrease the size of water droplets in the emulsion, allowing for a more homogenous mixture. With the aviation industry being a sizeable source of the global emissions caused by transportation, methods of lowering the emissions of aviation fuels as well as greener alternatives are needed. Present research quantitatively studies how the addition of ethanol to water and jet fuel emulsions affects the stability of the emulsion. A non-invasive, quantitative, and economical method for determining phase separation is used to study the stability of these multi-component mixtures. The system periodically measures the phase separation of the fluid column by automatically shining light through the fluid and detecting how much interference is created by the fluid. The system does this at five different depths of the fluid so the phase separation of the emulsion can be tracked in more detail. Ethanol and water are studied at mixtures of 5%, 10%, 15%, and 20% ethanol by weight and 5% and 10% water by weight emulsified with jet fuel. It is expected that the present research will lay additional foundation for the future study of fuel emulsion stability, as well as spark additional interest in utilizing emulsions to improve fuels.
Development of Single Piece Designed Compliant Locomotive Mechanism
Authors: Rouse Ciaphus , Estrada Benjamin , Sailors Caleb , Schneider Christian , Henderson Sean , Tekes Ayse 
Published: January 2022

Abstract
Biomimetic robots have been the focus of many studies for the last decades since the motion in nature is accomplished through the bending of the flexible arms once subjected to an input force, displacement or torque as opposed to their rigid body counterparts thereby increasing the workspace. This study presents the design, analysis, and modeling of a novel monolithically designed compliant mechanism. The mechanism consists of two translational springs, three sliding carts, housing for the two servo motors, and two rigid-flexure-rigid (RFR) arms. While the main body of the biomimetic robot can be 3D printed using polyethylene terephthalate glycol (PETG), the RFR links are 3D printed in thermoplastic polyurethane (TPU) to prevent yielding when loaded. The mechanism model is derived using D’Alembert’s principles, pseudo rigid body modeling, and kinematic constraints. Finite element analysis is performed in MSC Adams and simulation model outputs are validated through experimental data for forward motion.
A Study of Stress Intensity Factors in Lozenge Pattern of Joints
Authors: Hithendra K. , Prakash Raghu V. 
Published: January 2022

Abstract
Riveted joints are very crucial in many industrial applications. Several studies have been carried out to understand the response of lap joints and butt joints with single and double row of rivets emphasizing on total fatigue life and residual stress evaluation. Studies that deal with initial crack and stress intensity factors (SIF) during its progress are very less. In addition, there is very less data on joints formed with Lozenge pattern. The present work aims to bridge this gap with studies on the Lozenge pattern of rivets with focus on the SIF in strap plates, given the fact that the initial cracks appear on them when the strap thickness is less than or equal to the plate thickness. The strap plate considered has six joints in Lozenge pattern in 3-2-1 fashion. Cracks were induced at different joint locations and variation of the stress intensity factor with progress in crack size was evaluated using Finite Element Analysis. Studies were conducted for various interference levels of practical interest. The most critical location of the crack and the most beneficial levels of interference were identified. Limits of interference, beyond which SIF increases drastically, were identified. Combined influence of interference and neighboring geometrical aspects such as holes and boundaries was recorded. Studies were also conducted to evaluate if there is a need for uniform interference at all joint locations. Also, to simulate the real world scenario, several combinations of random interference were induced at the joints and the SIF results were compared with that of uniform interference values. Finally, the effect of change in back pitch of the joints was also studied.