bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.