bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrocaloric Cooling Prototype Using Lead-Free Barium Titanate Multilayer Capacitors and Heat Transfer Fluid Motion
Authors: Bellafkih S. , Hadj Sahraoui A. , Kulinski P. , Dumoulin P. , Longuemart S.
Published: November 2021

In this paper, we describe the realization and the testing of an electrocaloric effect based refrigeration prototype. The prototype makes use of Active Electrocaloric Regenerator (AER) made of commercially available MultiLayer ceramics and exploits the oscillating motion of a heat transfer fluid in a thermodynamic refrigeration cycle. The setup allows the adjustment of various parameters and the effect of the frequency of the cycle as well as the volume displaced of the heat transfer fluid has been evidenced. An amplification regenerative factor of 1.25 has been reached, comparable to those of previously proposed electrocaloric refrigerator prototypes.
Performance Analysis of Single-Phase Space Thermal Radiators and Optimization Through Taguchi-Neuro-Genetic Approach
Authors: Chiranjeevi P. B. , Ashok V. , Srinivasan K. , Sundararajan T.
Published: November 2021

In the thermal management of spacecraft, space thermal radiators play a vital role as heat sinks. A serial radiator with proven advantages in ground applications is proposed and analyzed for space applications. From the performance analysis, specific heat rejection (SHR) of serial radiator is found to be higher than parallel radiator by 80% for maximum diameter of the tube, 47% for maximum thickness of the fin, and 75% for maximum pitch of the tubes under consideration. Also, serial radiator requires four times higher pumping power than parallel radiator with geometric parameters and a maximum mass flowrate under consideration. In serial radiators, the cross conduction between the fins has a significant effect on its thermal performance. Thus, conjugate heat transfer simulations and optimization operations are to be performed iteratively to optimize the serial radiator, which is computationally costly. To reduce the computational time, artificial neural network (ANN) is trained using conjugate heat transfer simulations data and combined with the genetic algorithm (GA) to perform optimization. Taguchi’s orthogonal arrays provided the partial fraction of conjugate heat transfer simulations set to train the ANN. Taguchi-Neuro-Genetic approach, a process that combines the features of three powerful techniques in different optimization phases, is used to optimize both parallel and serial radiators. The optimization aims to obtain a configuration that provides the lowest mass and lowest pumping power requirement for given heat rejection. Optimization results show that the conventional parallel radiator is about 20% heavier and requires about 35% more pumping power than the proposed serial radiator.
Stochastic Crashworthiness Optimization Accounting for Simulation Noise
Authors: Ahmadisoleymani Seyed Saeed , Missoum Samy
Published: November 2021

Finite element-based crashworthiness optimization is extensively used to improve the safety of motor vehicles. However, the responses of crash simulations are characterized by a high level of numerical noise, which can hamper the blind use of surrogate-based design optimization methods. It is therefore essential to account for the noise-induced uncertainty when performing optimization. For this purpose, a surrogate, referred to as Non-Deterministic Kriging (NDK), can be used. It models the noise as a non-stationary stochastic process, which is added to a traditional deterministic kriging surrogate. Based on the NDK surrogate, this study proposes an optimization algorithm tailored to account for both epistemic uncertainty, due to the lack of data, and irreducible aleatory uncertainty, due to the simulation noise. The variances are included within an extension of the well-known expected improvement infill criterion referred to as Modified Augmented Expected Improvement (MAEI). Because the proposed optimization scheme requires an estimate of the aleatory variance, it is approximated through a regression kriging, which is iteratively refined. The proposed algorithm is tested on a set of analytical functions and applied to the optimization of an Occupant Restraint System (ORS) during a crash.
Sensor Fusion and On-Line Monitoring of Friction Stir Blind Riveting for Lightweight Materials Manufacturing
Authors: Gao Zhe , Khan Haris Ali , Li Jingjing , (Grace) Guo Weihong
Published: November 2021

This research focused on developing a hybrid quality monitoring model through combining the data-driven and key engineering parameters to predict the friction stir blind riveting (FSBR) joint quality. The hybrid model was formulated through utilizing the in situ processing and joint property data. The in situ data involved sensor fusion (force and torque signals) and key processing parameters (spindle speed, feed rate, and stacking sequence) for data-driven modeling. The quality of the FSBR joints was defined by the tensile strength. Furthermore, the joint cross-sectional analysis and failure modes in lap shear tests were employed to confirm the efficacy of the proposed model and development of the process–structure–property relationship.
Rotary Engine Rotor Side Seals Using New Machining Processes
Authors: Hsieh Yu-Yuan , Tsai Ming-Yi , Xu Zhi-Zhe
Published: November 2021

This study has developed a new machining process for the side seal components of gray cast iron alloy of rotor engine, which is different from the traditional wire electrical discharge machining (WEDM) process. The new manufacturing process (milling + grinding process) will save 78% of the cost and 83% of the time for making each side seal component, and the accuracy of the average surface roughness of the component will be 2.1 times that of the traditional manufacturing method. If the components are polished with a self-made polishing rod, the accuracy will be increased by almost 20 times compared with the new manufacturing process.
Laser Shock Peening Induced Back Stress Mitigation in Rolled Stainless Steel
Authors: Over Veronica , Lawrence Yao Y.
Published: November 2021

Laser shock peening (LSP) is investigated as a potential tool for reducing tensile back stress, shown here applied to rolled and annealed 304L austenitic steel. The back stress of treated and untreated dog-bone samples is extracted from hysteresis tensile testing. Electron back-scatter diffraction (EBSD) and orientation imaging microscopy (OIM) analysis quantify the geometrically necessary dislocation (GND) density distribution of unstrained and strained as well as unpeened and peened conditions. Finite element analysis (FEA) simulation models back stress and residual stress development through tensile testing and LSP treatment using known LSP pressure models and Ziegler's nonlinear kinematic hardening law. Nonlinear regression fitting of tensile testing stress–strain in as-received specimens extracts the kinematic hardening parameters that are used in numerical study. This research shows LSP may be used to overcome manufacturing design challenges presented by yield asymmetry due to back stress in rolled steel.
Performance, Combustion, and Emission Evaluation of Ethanol-Gasoline Blends Ignited by Diesel in Dual-Fuel Intelligent Charge Compression Ignition (ICCI) Engine
Authors: Zhang Yaoyuan , Zhao Wenbin , Wu Haoqing , He Zhuoyao , Qian Yong , Lu Xingcai
Published: November 2021

A recent proposed dual-fuel combustion mode, intelligent charge compression ignition (ICCI), realizes the high-efficiency and clean combustion by organizing continuous stratification in a wide range of engine load. The paper investigated the performance of alcohol blended gasoline as low-reactivity fuel (LRF) in ICCI combustion mode. Pure ethanol named E100 was also tested as LRF for comparison. To emphasize the differences of LRF properties and exclude the effect of the heat release phasing, the diesel injection timing was adjusted to maintain the same combustion phasing (CA50) at various LRF ratios under medium load. The results showed that E100 and E85 (ethanol ratio in gasoline-ethanol blend) promoted the degree of homogeneous combustion and eradicated soot emissions despite a slight increase of NOx. The maximum indicated thermal efficiency (ITE) was over 51.1% using E85, followed by 50.5% of E50. The perfect substitution ratio at the maximum ITE decreased from more than 80% to about 65% when increasing the ethanol ratio in LRF from 10% to 100%. The unregulated emissions such as aldehydes, ethylene, and methane, produced from incomplete combustion of ethanol were inhabited by E85, while the formation of toluene attributed to the appropriate carbon chain length of gasoline diminished when using E85 and E100.
Semi-Analytical Model for the Transient Analysis of the Pressure in Vertically Fractured Wells in Reservoirs Considering the Influence of Natural Fractures
Authors: Chen Yiming , Zhang Qiushi , Zhao Zhiming , Li Cunlei , Wang Bo
Published: November 2021

In addition to artificial fractures generated by hydraulic fracturing technology, natural fractures distributed in reservoirs will also affect the fluid flow process. To study the transient behavior of the pressure in fluid flows in reservoirs containing natural fractures, a semi-analytical model for vertically fractured wells with complex natural fracture networks was established. This model was based on the linear source function theory and the fracture discretization and coupling methods. It was solved by the Stehfest numerical inversion and the matrix transformation. The results of the study on the fluid flow stages in a reservoir with natural fractures indicated that the presence of natural fractures increased natural fracture flows. These flows were dominated by natural fractures and fracture interference stages and were different from the fluid flows observed in vertically fractured wells with a single main fracture. The sensitivity analysis on the influences of the fluid flow factors in the reservoirs with three types of natural fractures could provide a more detailed reference for the identification of the reservoir parameters and the transient characteristics of the flow stage. The different characteristic curves of the fluid flow in the reservoirs with different scale natural fractures could also provide a theoretical basis for determining the distribution of natural fractures in reservoirs.
Multi-Model Structured H-Infinity Design of a Robust and Aggressive Turbofan Jet Engine Controller
Authors: Authié Patrick
Published: November 2021

Jet engine control comprises tracking either the fan speed or engine pressure ratio setpoints. Further, safe operation entails maintaining several additional parameters, such as high-pressure turbine temperature, combustor pressure, core shaft acceleration, and other ones within prescribed limits. A Min-Max selector that features proportional-integral (PI) controllers is frequently used to handle these requirements. However, this arrangement is overly conservative in the limits management, which unnecessarily slows down the engine response. To overcome this shortcoming, a new controller that adopts the traditional Min-Max structure in combination with the Ndot control, the Conditionally Active and the Conditioning Technique approaches is developed. PI regulators are replaced by dynamic output feedback controllers, which are designed according to a multi-model structured H-infinity methodology. This approach makes it possible to marry robustness with performance, which are two conflicting objectives. Singular value analysis tools demonstrate the robustness of the resulting design. Linear and nonlinear simulations indicate that the proposed controller optimizes the engine response time under the constraint of keeping a set of parameters within prescribed bounds. The features of the proposed design are lucrative for actual implementation in the industry.
Evaluation of Arc Stability in Double-Wire DP-GMAW of Aluminum Alloy Based on U-I Graph
Authors: Wu Kaiyuan , Zhang Mingjin , Zeng Yucai , Hong Xiaobin , Xie Peimin
Published: November 2021

Severe arc interference in double-wire double pulsed gas metal arc welding (DP-GMAW) can affect the stability of the welding process. In this study, voltage and current waveforms during double-wire DP-GMAW of aluminum (Al) alloy in the 0 deg and 180 deg phase shift modes were recorded. The relationship between arc voltage and welding current was investigated through the output voltage-current (U-I) graph. In addition, arc load characteristics and variation of voltage and current during the DP switching process were analyzed. The arc behavior was recorded throughout the welding process using a high-speed photography system, and the relationship between the U-I graph characteristics and arc stability was further investigated. The experimental results demonstrate that the arc is more stable in the 180 deg phase shift mode. In both phases, the leading arc impedance is more capacitive, and the trailing arc impedance is more resistive.
On Force–Displacement Characteristics and Surface Deformation in Piezo Vibration Striking Treatment
Authors: Chen Jisheng , Xu Yang , Sandoval Juan , Kwon Patrick , Guo Yang
Published: November 2021

This paper presents an experimental study on a novel mechanical surface treatment process, namely piezo vibration striking treatment (PVST), which is realized by a piezo stack vibration device installed on a computer numerical control (CNC) machine. Unlike other striking-based surface treatments, PVST employs non-resonant mode piezo vibration to induce controllable tool strikes on the workpiece surface. In this study, an experimental setup of PVST is implemented. Four types of experiments, i.e., tool-surface approaching, single-spot striking, one-dimensional (1D) scan striking, and 2D scan striking, are conducted to investigate the relationships among the striking force, tool vibration displacement, and surface deformation in PVST. The study shows that PVST can induce strikes with consistent intensity in each cycle of tool vibration. Both the striking intensity and striking location can be well controlled. Such process capability is particularly demonstrated by the resulting texture and roughness of the treated surfaces. Moreover, two linear force relationships have been found in PVST. The first linear relationship is between the striking force and the reduction in vibration amplitude during striking. The second one is between the striking force and the permanent indentation depth created by the strike. These linear force relationships offer the opportunity to realize real-time monitoring and force-based feedback control of PVST. This study is the first step toward developing PVST as a more efficient deformation-based surface modification process.
Sliding Wear Characteristics of a-C:H:SiOx Coatings
Authors: Grenadyorov A. S. , Solovyev A. A. , Oskomov K. V.
Published: November 2021

The paper presents the experimental study of the friction and wear characteristics of amorphous carbon coating containing hydrogen and SiOx (a-C:H:SiOx) deposited onto WC-8Co cemented carbide substrates. A 5 µm thick a-C:H:SiOx coating was fabricated using plasma-assisted chemical vapor deposition (PACVD). The tribological properties of the a-C:H:SiOx coating sliding in contact with WC–8Co, ZrO2, SiC, Si3N4 counter bodies are examined using the ball-on-disc method at different normal loads and sliding speeds. Tribology testing shows that the minimum values of the friction coefficient (0.044) and the wear-rate (9.3 × 10−8 mm3/N·m) are observed when using a counter body made of silicon nitride at a 5 N indentation load. The load increase from 5 to 12 N raises the friction coefficient up to 0.083 and the wear-rate up to 46 × 10−8 mm3/N·m. When the sliding speed reaches its critical value, the coating friction provides the transition from sp3 hybridized to sp2 hybridized and polymeric carbon, which is accompanied by the reduction in the friction coefficient. The a-C:H:SiOx coating provides an increase in the critical sliding speed up to 50–75 mm/s, which exceeds that of nonalloyed (a-C and a-C:H) diamond-like carbon coatings as a result of doping by silicon and oxygen.
Mechanism of Band Gaps in Self-Similar Triangular Lattice With Koch Fractal
Authors: Zhao Pengcheng , Zhang Kai , Zhao Cheng , Deng Zichen
Published: November 2021

Fractal lattice is a kind of lattices with multifunctional physical characteristics and superior mechanical properties. The wave propagation of the triangular lattice with Koch fractal is calculated by the finite element method and Bloch theorem. The effects of the iteration number on the band gaps and the band edge modes are studied. The finite element software was used to simulate the dynamic response of the triangular lattice with Koch fractal for verifying the vibration suppression performance. The results show that the triangular lattice with Koch fractal can produce multiple and low-frequency band gaps. As an increase of the iteration number, the band gap gradually shifts to a lower frequency. By comparing and analyzing the band edge modes and the eigenmodes of Koch fractal, the mechanisms of the band gaps within the low-frequency ranges are analyzed and discussed in detail. Additionally, the band edge modes exhibit similar vibration modes. Finally, the simulation results of the finite lattice verify the broadband vibration suppression performance of the triangular lattice with Koch fractal. This work provides insights into the lattice dynamic behavior adjusted by Koch fractal, which is beneficial to the periodic lattice for suppressing vibration in engineering applications.
Distributed Dynamic Signal Analysis of Piezoelectric Laminated Linear and Nonlinear Toroidal Shells
Authors: Tzou H. S. , Wang D. W. , Hagiwara I.
Published: November 2021

Toroidal shells belong to the shells of revolution family. Dynamic sensing signals and their distributed characteristics of spatially distributed sensors or neurons laminated on thin toroidal shell structures are investigated in this study. Spatially distributed modal voltages and signal patterns are related to the meridional and circumferential membrane/bending strains, based on the direct piezoelectricity, the Gauss theorem, the Maxwell principle and the open-circuit assumption. Linear and nonlinear toroidal shells are defined based on the thin shell theory and the von Karman geometric nonlinearity. With the simplified mode shape functions defined by the Donnell-Mushtari-Vlasov theory, modal dependent distributed signals and detailed signal components of spatially distributed sensors or neurons are defined and these signals are quantitatively illustrated. Signal distributions basically reveal distinct modal characteristics of toroidal shells. Parametric studies suggest that the dominating signal component originates from the meridional membrane strains. Shell dimensions, materials, boundary conditions, natural modes, sensor locations/distributions/sizes, modal strain components, etc. all influence the spatially distributed modal voltages and signal generations.
Optimal Piezoelectric Actuator Sizing Based on Random Disturbance Data
Authors: Zaki A. S. , Ghandi K. , Bent A. A.
Published: November 2021

In general, active damping actuators are sized to induce a prescribed level of damping in the structure in the presence of specified disturbance. Unfortunately, structural disturbances cannot be measured directly. Instead, the effect of disturbances on structural response (e.g. deflection, strain, acceleration, etc.) are quantified either in a stochasitic (i.e. spectral data such as autospectrum) or deterministic (i.e. time history data).

In this paper, a technique for sizing actuators based on stochastic disturbance information is presented. From the power spectral density of the response, the peak disturbance at each structural mode of interest can be computed as well as the total RMS of the response. A structural dynamic model is synthesized using either finite element analysis or Rayleigh-Ritz formulation. Based on this information, the disturbances can be estimated which is later used to determine whether the actuator size and configuration are sufficient to introduce the prescribed level of damping.

The above algorithm is used to design and compare actuators configuration to reduce the vibration on F18 tail model. A comparison between active fiber composite (AFC) actuators and regular d31 actuators is presented. Simulation results show that the AFCs have more authority than the regular d31 actuator.
Application of Kautz Models for Adaptive Vibration Control
Authors: Mayer Dirk , Herold Sven , Hanselka Holger
Published: November 2021

Both for active noise control (ANC) and active vibration control (AVC) the well known F-X-LMS-algorithm can be used. This approach requires a proper model of the path from the actuator to the error sensor, preferably received with an on-line identification. In the field of ANC adaptive finite impulse response (FIR) filters work well for this task, but for lightly damped mechanical systems with long impulse responses FIR filters with up to several thousand coefficients would have to be used. One alternative are adaptive IIR filters, but these can get unstable while adapting or the adapting process can get stuck in local minima. In this work, adaptive Kautz models are introduced, which need some a priori knowledge about the poles of the system. On the other hand, they represent an infinite impulse response while maintaining the transversal structure of the adaptive filter. This is reached by generalization of the FIR filter, for which the delay operator is substituted by discrete allpass filters, the Kautz filters. The adaptive filter bank is implemented by means of the straightforward LMS algorithm in the Matlab/Simulink environment. As an example, system identification with Kautz models and their usage in AVC for a simple mechanical system will be studied.
Design and Experimental Validation of Adaptive Neurocontroller for Beam Vibration Suppression Using Piezoelectric Actuators
Authors: Jha Ratneshwar , He Chengli
Published: November 2021

A neural network based adaptive controller for smart structures is designed and validated experimentally. For a truly adaptive control system, the neurocontroller learns online in real time. The Levernberg-Marquardt backpropagation algorithm is implemented for fast learning. Piezoelectric actuators are employed to suppress the vibrations of a cantilevered beam subject to impulse, sine wave, and band-limited white noise disturbances. Experimental results demonstrate excellent closed-loop performance and robustness of the adaptive neurocontroller.
Stress Effects in Ferroelectric Thin Films
Authors: Lian L. , Sottos N. R.
Published: November 2021

PZT (52/48) film response is measured as a function of externally applied mechanical stress using a double-beam laser-Doppler heterodyne interferometer. One laser beam is focused on the front film surface and a second is focused on the back of the substrate. This arrangement successfully eliminates any displacement contribution from flexural vibration of the substrate and enables measurement of the strain–electric field hysteresis loops as a function of applied stress. The field-induced strain in the PZT film increases as the applied uniaxial compressive stress increases, and the opposite trend is observed for applied tensile stress. The dependence of electromechanical response on the external stress is attributed to the initial tensile residual stress state in the film. Tensile stress creates an in-plane clamping effect on the domains in the film, hindering polarization switching. The application of a compressive stress reduces the tensile residual stress in the film and the constraint on the domains, hence more 90° polarization switches are allowed to occur under applied electric field, leading to higher field-induced strains. Applied tensile stress amplifies the clamping effect, leading to lower field-induced strains.
Temperature Rise in the Reacted Zone of Electrochemical Devices With Porous Electrodes
Authors: Hall Carsie A. , Russo Edwin P. , Mackie Calvin
Published: November 2021

A model to predict the temperature rise in the reacted zone of discharging electrochemical devices has been developed. The model assumes that electrode kinetics are fast and concentration gradients are negligible. In the model, the temperature rise is predicted using the one-dimensional heat diffusion equation for a porous medium. The instantaneous power per unit area dissipated in the reacted zone is used as a source term in the heat diffusion equation. With fixed parameters such as discharge current density, charge capacity per unit volume, electrode electrical conductivity, electrode porosity, and thermophysical properties of the pore-space fluid and electrode, the transient temperature distribution in the reacted zone is calculated as a function of time. An analytical solution is derived for the transient temperature distribution in the reacted zone. Subsequently, the maximum electrode temperature is readily obtained, and the maximum electrode temperature at complete discharge is derived.
Application of Computational Fluid Dynamics in Reciprocating Compressor Design
Authors: Possamai Fabricio C. , Fagotti Fabian
Published: November 2021

Heat and mass transfer processes are of paramount importance when designing some important compressor components, specially the ones that perform flow control, noise suppression and the compression process itself. In general, pressure losses, flow pulsation and heat exchanges must be minimized to achieve high efficiencies. On the other hand, the optimization of those parameters are subject to a compromise among noise generation, component manufacturing costs and reliability, hence the bigger is the amount of (correct) information available, the higher is the probability of a successful project. In this scenario, the use of Computational Fluid Dynamics (CFD) plays an important role in the development phase, since it allows the analysis of more options, faster and at lower expenses comparing to the “prototype-and-test” approach. It also spreads possibilities of alternatives prone to be considered in a technical trade-off and anticipates problems and design constrains prior to prototyping. This paper focus on case studies and designing problems solved by the authors using different CFD based approaches. The problems are described in terms of the approach used in the solution, boundary conditions, models adopted and results obtained.
Multi-Element Unstructured Methodology for Turbomachinery Applications
Authors: Ahuja V. , Arunajatesan S. , Hosangadi A.
Published: November 2021

Simulations for turbomachinery applications in various flow regimes are presented using a multi-element unstructured CFD code CRUNCH. The unstructured framework permits the generation of a contiguous grid without internal boundaries between different components of a turbomachinery system, and provides good local resolution in regions where the flow physics becomes important. The increased numerical stability resulting from these factors coupled with the parallel solution framework yields an efficient solution procedure for complex turbomachinery flows. Numerical results are presented for a transonic diffuser-volute configuration and rotor stator interaction.
Unstructured Rotor-Stator Analysis of Axial Turbomachinery Using a Pressure Based Method
Authors: Yu Wen-Sheng , Kunz Robert F. , Ettorre Stephen M. , Antal Steven P.
Published: November 2021

An implicit, unstructured, parallel CFD formulation is presented for the analysis of multistage turbomachinery flow fields. The differential model employed is the compressible Reynolds averaged Navier-Stokes equations. A cell-centered finite-volume pressure based scheme is employed. The use of hybrid unstructured grids, second order discretization numerics and an interface sliding algorithm enable efficient and accurate resolution of wake decay and wake-blade interaction physics. Specifically, stationary-rotating reference frame interfaces can be easily placed very close to the leading edge of downstream blade rows. Also, a large number of elements can be used to resolve the wake and down-stream blade inlet regions without an attendant increase in the total number of elements associated with block and overset structured mesh schemes.

In this paper, details of the CFD formulation and physical modeling are first summarized, with emphasis placed on unstructured, rotor-stator and parallel processing elements. Results are presented for the analyses of a single stage axial turbine and a single stage axial pump, both of which have been the subject of numerous experimental and computational studies.
Energy and Exergy Analyses of the Pulse Detonation Engine
Authors: Hutchins Timothy E. , Metghalchi Mohamad
Published: November 2021

Energy and exergy analyses have been performed on a pulse detonation engine. A pulse detonation engine is a promising new engine, which uses a detonation wave instead of a deflagration wave for the combustion process. The high-speed supersonic combustion wave reduces overall combustion duration resulting in a nearly constant volume energy release process compared to the constant pressure process of gas turbine engines. Gas mixture in a pulse detonation engine has been modeled to execute the Humphrey cycle. The cycle includes four processes: isentropic compression, constant volume combustion, isentropic expansion and isobaric compression. Working fluid is a fuel-air mixture for unburned gases and products of combustion for burned gases. Different fuels such as methane and JP10 have been used. It is assumed that burned gases are in chemical equilibrium states. Both thermal efficiency and effectiveness (exergetic efficiency) have been calculated for the pulse detonation engine and simple gas turbine engine. Comparison shows that for the same pressure ratio pulse detonation engine has better efficiency and effectiveness than the gas turbine system.
Rational Design of Vehicles: II — Subsystem Decomposition
Authors: Paulus David M. , Gaggioli Richard A.
Published: November 2021

Overall vehicle design entails the subsidiary design — concurrent engineering — of the numerous subsystems that make up the vehicle. The engineer(s) in charge of the overall design must coordinate the work and integrate the designs of several “independent” subsystem design teams. That coordination and integration is achieved by specification of a particular set of constraints, imposed upon each design team. As the overall design proceeds, as a result of feedback from and review of the work of the individual teams, these constraints may be adjusted. Then many of the subsystems need to be re-designed. This procedure is carried out, iteratively, until “convergence” is achieved. That is, until the overall design is “suitable and satisfactory” in the judgment of the engineer in charge of the overall design, in consultation — directly or indirectly — with the “customer(s).” Better yet, the iterative procedure is continued until a rational objective function for the overall vehicle is optimized. In order to facilitate this concurrent engineering process, it is desirable that the design decisions, being made by the subsystem design teams, explicitly take into account the customers’ weighted desiderata for the overall system. In this paper, it is shown how the methods of thermoeconomic decomposition can be applied (in conjunction with the rational objective function for the overall design presented in Part I) to deduce objective functions for optimizing the design of energy-conversion subsystems. An illustrative case study is presented, for the design-selection of an engine and a generator for a light aircraft.
Integration of Fuel Cell Technology Into Engineering Thermodynamic Textbooks
Authors: Chen Eric L. , Chen Pah I.
Published: November 2021

The time has come for engineering thermodynamic texts to look beyond the limitations of heat engines. As different power generation technologies are implemented, texts should reflect the changes. In doing so, students will be better prepared to contribute to those new fields in industry or academia. An example is fuel cell technology, a field that is making rapid progress toward commercialization, but one that still requires more research and development. Now is the time to include fuel cell technology in thermodynamic texts, introducing students to the basic science and engineering principles.

This paper proposes that fuel cell technology be integrated into textbooks with examples and applications included in certain chapters. The fundamental principles of fuel cells are presented, along with the most suitable chapter in which the material should appear. Students will benefit from the material because fuel cells will add variety to the examples, extending the thermodynamic principles to other applications. Instructors, however, will have to decide if their syllabi can accommodate the extra material.
Exergetic and Thermoeconomic Analysis of a 200-KW Phosphoric Acid Fuel Cell Plant
Authors: Kwak Ho-Young , Lee Hyun-Soo , Jeon Jin-Seok , Choi Dongsoo
Published: November 2021

Exergetic and thermoeconomic analysis were performed for a 200-kW Phosphoric Acid Fuel Cell (PAFC) plant which offers advantage for cogeneration in the aspect of high electrical efficiency and low emission. This analytical study was based on data obtained by in-field measurement of PC25C fuel cell plant to find whether this system is viable. For 100% load condition, the electrical efficiency and the unit cost of electricity are about 45% and 0.032 $/kWh respectively, which turn out to be much better than those for a 1000-kW gas turbine cogeneration plant. Further, at lower loads, the unit costs of electricity and hot water increase slightly and consequently more economic operation is possible at any loads.
On- and Off-Design Performance of the Feedwater Heating Combined Cycle
Authors: Zhang Na , Cai Ruixian
Published: November 2021

Feedwater heating combined cycle is one of the CC-repowering means for the conventional PC power station improvement. The preferable characteristics of such combined cycle to be used in China and other developing countries for repowering are its comparably lower investment, less oil/gas consumption, especially its low technical difficulties and easier accomplishment. The concise performance expressions for the existing steam station repowering are derived, and highlight is put to the combined cycle off-design performance study. It is pointed out that there are some problems deserving more attention for the part-load operation. The performances of several different operating scenarios are analyzed, and the better one is recommended based on the comparison.
Effect of Graft Material on Anterior Cruciate Ligament Reconstruction: A 3D Computational Simulation
Authors: Suggs Jeremy F. , Li Guoan
Published: November 2021

The effect of graft materials on knee kinematics after ACL reconstruction was investigated parametrically using a 3D finite element knee joint model. The results demonstrated that a stiff graft, such as the current BPTB graft, may overcorrect the kinematics of an ACL deficient knee. A less stiff graft, under appropriate initial tension, may better restore the intact kinematics.
Rising Crack-Growth-Resistance Behavior in Cortical Bone: Implications for Toughness Measurements
Authors: Vashishth Deepak
Published: November 2021

Application of fracture mechanics to bone was undertaken to provide a better estimate of bone’s resistance to fracture as traditional strength of materials tests failed to provide a realistic measure due to the presence of inherent flaws and fatigue microcracks in bone (1). Consequently, over the last decade a number of fracture mechanics studies have characterized bone’s resistance to fracture in terms of critical stress intensity factor and critical strain energy release rate measured at the onset of a fracture crack (1–3). These studies, although useful, provide a limited insight into fracture behavior of bone as, unlike classical brittle materials, bone is a microcracking solid that derives its resistance to fracture during the process of crack propagation from microfracture mechanisms occurring behind the advancing crack front (4). More significantly age and disease-related alterations in the content and arrangement of bone, that cause reduced post-yield properties, are unlikely to be realized from initiation tests as such tests are limited to events at yielding.
Numerical Simulation and Evaluation of the Reduced-Platen Compression Test for Estimating Cancellous Bone Mechanical Properties in the Rat
Authors: Hogan Harry A. , Harms Kent D. , Sampson H. Wayne
Published: November 2021

Animal models are utilized in numerous research studies aimed at better understanding skeletal biology, bone biomechanics, and many orthopedic diseases or pathologies. Prominent among these animal models are rodents, most commonly rats and mice. In estimating bone mechanical properties in these animals, cortical bone is routinely assessed by bending one of the long bones such as the femur or tibia, which targets the mid-diaphysis region. Testing specimens of isolated cancellous bone is exceedingly challenging, however, even for the larger rat skeleton. Recognizing the prominence and importance of cancellous bone mechanical properties has led to increased mechanical testing of vertebra and femoral neck specimens in skeletal research employing rats and mice. The specimens in these tests actually consist of a combination of both cortical and cancellous tissue, however. In an attempt to more closely approximate the ideal of isolated cancellous bone specimens a method has been developed recently for testing specimens from the proximal tibia metaphysis and distal femoral metaphysis [1]. In either case, the specimen in this so-called “reduced-platen compression” (RPC) test consists of a section of the metaphysis containing both cortical and cancellous bone. The specimen and test configuration are illustrated schematically in Fig. 1.
Predicting a Power Law Between Elastic Modulus and Porosity in Cortical Bone: A Micromechanics Model
Authors: Dong X. Neil , Guo X. Edward
Published: November 2021

Age-related changes in microstructure and composition of bone tissue are becoming increasing important as people continue to live longer. The cortical porosity increases with age in both men and women [1]. Age related increases in Haversian canal size and Haversian canal number contribute to the increasing porosity of cortical bone for the elderly men and women [2, 3]. The number of osteoclastic resorption space is also greater in the old men than in the young men [3]. The increased porosity and the higher prevalence of giant Haverian canals have a markedly negative influence on the ability of the cortical shell to withstand mechanical loads associated with a fall [4].
Measurement of the Spatial Motion of the Ankle-Subtalar Complex
Authors: Ying Ning , Kim Wangdo
Published: November 2021

A modified Euler angles method, dual Euler angles approach, has been proposed to describe exact joint motion. In the dual Euler angles method, joint motion is considered as three successive screw motions with respect to the axes of the moving segment coordinate system and the screw motion displacements are represented by dual angles accordingly. The algorithm for calculating dual Euler angles from coordinates of markers on joint segments has also been provided. In this paper, the dual Euler angles method is applied to describe the motion of ankle joint during dorsiflexion-plantarflexion. Due to the difficulty in tracking the motion of the talus segment in vivo, only the overall motion of the ankle-subtalar complex, that is, the relative motion of the foot with respect to the shank, was measured in the present study.
Local Force on Cell Cytoskeletons Causes Binding of Focal Contact Proteins Dependent Upon Tyrosine Phosphatase/Kinases
Authors: Sheetz M. P.
Published: November 2021

Cellular responses to mechanical force are critical for the shaping of cells and for many physiological functions that need to be satisfied in functionally engineered tissues. From several recent observations, there is the suggestion that physical force developed by a cell or its environment can signal to the cell through oncogenic tyrosine kinase/phosphatase pathways and alter the program of the cell. These responses occur in seconds and lead to the localization of focal contact proteins at the sites of maximum force on the cytoskeleton. We suggest that forces directly applied to cytoskeleton proteins cause the activation of the cellular responses.
Design of a V-Plate-Wire Mandibular Fixation System
Authors: Trabia Mohamed B. , Zobotkin Konstantin G. , Wang Robert C.
Published: November 2021

This paper presents a novel method for internal fixation of unstable mandibular fractures. The fixation method uses a three-screw V-shaped plate and a wire. Two screws are placed normal to the fracture line. The plate is first attached to one of the screws. A wire is then passed around the plate and the opposite screw and tightened to bring the two sides of the fracture together and align them. The plate is then fixed to the other side of the fracture using two additional screws. The fixation system is designed such that the plate carries most of the load. Finite element modeling of the system shows that the method is reliable, producing low stresses. The proposed method presents a simple and quick alternative to the usual plates currently used for mandibular fixation.
Customized Resurfacing of the Knee: Design of the Shell Knee Replacement
Authors: Duncan Naphysah O. , Walker Peter S. , Potter Hollis G.
Published: November 2021

Current total knee replacements have been successful in relieving the pain associated with arthritis, as well as increasing patient mobility and allowing them to partake in sports activities to a limited degree. In the elderly patient group, the ten-year survivorship has been as high as 95%. Approximately, one-third of the patients who are candidates for total knee replacement fall into the younger patient group category. In this group, where life expectancy can exceed 20 years[1], the survivorship of a TKR is limited. This becomes an important issue since one or more revision surgeries may be necessary. As a result, the chances of infection, pain associated with surgery and rehabilitation, and loss of viable bone are increased. Achieving a high degree of mobility is also a priority for this group since they tend to lead a more active lifestyle.
A Total Knee Replacement Model for Evaluation of Joint Mechanics
Authors: Halloran Jason P. , Rullkoetter Paul J.
Published: November 2021

The success of current total knee replacement (TKR) devices is contingent on the kinematics and contact mechanics during in vivo physiological activity. A great deal of research has gone into determining parameters important to proper long-term joint function. Indicators of potential wear performance in ultra-high molecular weight polyethylene (UHMWPE) total joint replacement components include contact stress and area due to articulations, and tibio-femoral and patello-femoral kinematics. All have been used to compare implant designs and serve as a basis for differentiation of systems.
FEA Optimization of Pedorthic Treatment for Podalgia
Authors: Houston Vern L. , Luo Gangming , Mason Carl P. , Mussman Martin , Garbarini MaryAnne , Beattie Aaron C. , Thongpop Chaiya
Published: November 2021

Foot problems are quite common. Epidemiological studies have shown as many as 86% of elderly individuals report having problems with their feet, ranging from calluses, cracking and ingrown nails to inflammation, swelling, ischemia, ulceration, and gangrenous necrosis [1]. Persons suffering chronic Diabetes Mellitus are at particular risk of trauma to their feet because of peripheral neuropathy, plantar fat pad and muscle atrophy, and vascular insufficiency. Half of all lower limb amputations each year in the United States are performed on diabetics because of foot and ankle injuries that fail to heal [2]. At the very least, podalgia and pedal trauma restrict person’s mobility and limit their independence, impacting their fiscal as well as their physical well-being. With the exception of memorable catastrophic events, the etiopathogenesis of podalgia and other problems contributing to pedal trauma are generally not well understood. In work with Hansen’s disease and diabetic patients, Brand et al. [3] showed that stresses as small as 1/2 psi could produce trauma in the foot fat pads of even healthy animals, if chronically and repetitively applied without adequate time for tissues to recover and rest, Pedorthic insoles (often with orthopedic shoes) are prescribed for curative as well as prophylactic treatment of podalgia and pedal trauma, especially for diabetic patients with peripheral vascular disease, and arthritic patients with osseous deformity. There are hundreds of such devices commercially available, that range in composition and mechanical characteristics from extremely soft silicone elastomers to stiff plastic and metal plates. They maybe thin or thick, flat or custom milled with precision CAD/CAM systems using 3D laser scans of the individual’s feet to match their pedal contours. Although numerous studies [4, 5, 6] have been conducted, measuring pedal plantar interface stresses, no general quantitative principles for design, performance assessment, or prescription have been developed. These procedures remain highly subjective, and quite variable, depending upon the training, experience, and skill of the patient’s pedorthotist, podiatrist, and/or physcian. The objective of this study was to investigate the stresses and strains incurred in the soft plantar tissues of the foot as a function of insole material and design geometry to enhance understanding of footwear biomechanics and contribute to development of quantitative criteria for prescription, design, and performance assessment of pedorthic footwear.
Obstruction Detection in the Upper Airways Using Input Impedance in the Frequency Domain
Authors: Al-Jumaily A. M. , Du Y.
Published: November 2021

This research focuses on establishing an appropriate theoretical technique for identifying an obstruction in a flexible compliant tube such as the trachea. The input impedance frequency spectrums for both a healthy and an obstructed airway are used as a signature to determine and examine the constriction location, severity and degree. Uniform and gradual types of constriction are considered and the results demonstrate that the input impedance resonant frequencies can map the location, severity and degree of an obstruction.
Simulated Mucus Clearance in Horizontal vs. Vertically Inclined Rigid Tracheal Model
Authors: Evrensel Cahit A. , Öz Halil R. , Krumpe Peter E. , Hassan Amgad A.
Published: November 2021

Epithelia of conducting airways is lined with a layer of mucus above a layer of serous fluid. Mucus is a viscoelastic gel, while the serous layer is identified as “watery”. In normal airways, the mucociliary transport system forms the primary basis for clearance of mucus. Dehydration results in the disappearance of serous layer and impairs the mucociliary clearance. For these persons two-phase gas-liquid flow and cough become the dominant mechanisms.
Left Ventricular Filling Dynamics: Particle Image Velocimetry and Ultrasound Color M-Mode Imaging
Authors: Shandas Robin , Hertzberg Jean R. , Cooke Jason E. , Boardman Matthieu
Published: November 2021

Studies have shown that left ventricular diastolic function is an important indicator of overall cardiac health [1,2]. Quantitation of diastolic function using non-invasive imaging techniques continues to be a long-standing goal for clinicians. The recent development of ultrasound Doppler color M-mode imaging techniques to measure the speed of flow propagation within the ventricle during diastole appears promising in this regard. However, significant subjectivity in measuring flow propagation speed exists. One reason for this is that the relationship between clinically derived parameters such as color M-mode flow propagation and underlying fluid mechanics of diastolic filling is still unclear.