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Development of efficient and accurate skeletal mechanisms for hydrocarbon fuels and kerosene surrogate

Acta Mechanica Sinica 2015年第5期31卷 732-740页

作者： Fengquan Zhong Sugang Ma Xinyu Zhang chih-jen sung Kyle E.Niemeyer State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of Sciences Department of Mechanical Engineering University of Connecticut School of Mechanical Industrialand Manufacturing EngineeringOregon State University

In this paper,the methodology of the directed relation graph with error propagation and sensitivity analysis（DRGEPSA）,proposed by Niemeyer et al.（Combust Flame 157：1760-1770.2010）.and its differences to the original directed relation graph method are *** DRGEPSA,the detailed mechanism of ethylene containing 71 species and 395 reaction steps is reduced to several skeletal mechanisms with different error *** 25-species and 131-step mechanism and the 24-species and115-step mechanism are found to be accurate for the predictions of ignition delay time and laminar flame *** further reduction leads to a smaller skeletal mechanism with 19 species and 68 steps,it is no longer able to represent the correct reaction *** the DRGEPSA method,a detailed mechanism for n-dodecane considering low-temperature chemistry and containing 2115 species and8157 steps is reduced to a much smaller mechanism with249 species and 910 steps while retaining good *** considering only high-temperature（higher than 1000 K）applications,the detailed mechanism can be simplified to even smaller mechanisms with 65 species and 340 steps or48 species and 220 ***,a detailed mechanism for a kerosene surrogate having 207 species and 1592 steps is reduced with various error thresholds and the results show that the 72-species and 429-step mechanism and the66-species and 392-step mechanism are capable of predicting correct combustion properties compared to those of the detailed *** is well recognized that kinetic mechanisms can be effectively used in computations only after they are reduced to an acceptable size level for computation capacity and at the same time retaining ***,the skeletal mechanisms generated from the present work are expected to be useful for the application of kinetic mechanisms of hydrocarbons to numerical simulations of turbulent or supersonic combustion.

关键词： Reduced chemistry Hydrocarbons Directed relation graph Ignition delay time

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Performance of supersonic model combustors with staged injections of supercritical aviation kerosene

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Acta Mechanica Sinica 2010年第5期26卷 661-668页

作者： Feng-Quan Zhong Xue-Jun Fan Gong Yu Jian-Guo Li chih-jen sung LHD Institute of Mechanics Chinese Academy of Sciences100190 Beijing China University of Connecticut Storrs CT 06269 USA

Supersonic model combustors using two-stage injections of supercritical kerosene were experimentally investigated in both Mach 2.5 and 3.0 model combustors with stagnation temperatures of approximately 1,750 K. Supercritical kerosene of approximately 760 K was prepared and injected in the overall equivalence ratio range of 0.5-1.46. Two pairs of integrated injector/flameholder cavity modules in tandem were used to facilitate fuel-air mixing and stable combustion. For single-stage fuel injection at an upstream location, it was found that the boundary layer separation could propagate into the isolator with increasing fuel equivalence ratio due to excessive local heat release, which in turns changed the entry airflow conditions. Moving the fuel injection to a further downstream location could alleviate the problem, while it would result in a decrease in combustion efficiency due to shorter fuel residence time. With two-stage fuel injections the overall combustor performance was shown to be improved and kerosene injections at fuel rich conditions could be reached without the upstream propagation of the boundary layer separation into the isolator. Furthermore, effects of the entry Mach number and pilot hydrogen on combustion performance were also studied.

关键词： Supersonic combustion Staged injection Combustion efficiency Supercritical kerosene

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Fundamental investigations for lowering emissions and improving operability

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Propulsion and Power Research 2018年第3期7卷 197-204页

作者： Xiao Ren Xin Xue Kyle B.Brady chih-jen sung Hukam C.Mongia Department of Mechanical Engineering University of ConnecticutStorrsCT 06269USA National Research Council Air Force Research LaboratoryWPAFBOH 45433USA CSTI Associates LLCYardleyPA 19067USA

This paper first highlights recent developments in lean direct injection(LDI)combustion *** view of the needs and opportunities to lower emissions and expand the operability range of LDI,fundamental research has been undertaken to elucidate the effects of air swirler vane angle,air swirler rotation direction,and overall equivalence ratio on the LDI flow field and flame structure/***,additional investigation has been conducted to understand the fundamental differences between representative LDI and airblast injectors in order to highlight the importance of the flare feature to LDI venturi *** results of these fundamental studies are discussed to help identify possible areas for optimization to generic LDI designs that may improve individual swirler performance.

关键词： Gas turbine combustor Low emissions Lean direct injection Airblast injector Swirl-venturi configuration

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Rational Schur Superalgebras

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Algebra Colloquium 2024年第2期31卷 209-220页

作者： Andrew Riesen Shun-jen Cheng Department of Mathematical and Statistical Sciences University of Alberta 1132489 Ave NWEdmontonAlbertaCanada 不详

We develop and study the generalization of rational Schur algebras to the super *** to the classical case,this provides a new method for studying rational supermodules of the general linear supergroup GL(m|n).Furthermore,we establish a Schur-Weyl duality result for rational Schur superalgebras and conclude that under certain conditions these objects will be semisimple.

关键词： Schur algebra supermathematics general linear supergroup

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A Blade Altering Toolbox for Automating Rotor Design Optimization

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Communications on Applied Mathematics and Computation 2024年第1期6卷 688-704页

作者： Akiva Wernick jen-Ping Chen Mechanical and Aerospace Engineering The Ohio State University201 W.19th Ave.ColumbusOH43210USA

The Blade Altering Toolbox(BAT)described in this paper is a tool designed for fast reconstruction of an altered blade geometry for design optimization *** BAT algorithm is capable of twisting a given rotor’s angle of attack and stretching the chord length along the span of the *** test cases were run using the BAT’s *** BAT code’s twisting,stretching,and mesh reconstruction capabilities proved to be able to handle reasonably large geometric alterations to a provided input rotor *** test examples showed that the toolbox’s algorithm could handle any stretching of the blade’s chord as long as the blade remained within the original bounds of the unaltered *** algorithm appears to fail when the net twist angle applied the geometry exceeds approximately 30 degrees,however this limitation is dependent on the initial geometry and other input ***,the algorithm is a very powerful tool for automating a design optimization procedure.

关键词： Mesh reconstruction Mesh alteration Rotor alteration Design optimization

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Sutured scleral fixation of existing subluxated/dislocated acrylic one-piece intraocular lenses

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International Journal of Ophthalmology(English edition) 2024年第4期17卷 665-669页

作者： Wei-Yu Huang Yung-jen Chen Department of Ophthalmology Chi Mei Medical CenterTainan City 710TaiwanChina Department of Ophthalmology Chang Gung Memorial HospitalKaohsiung City 833TaiwanChina

AIM:To evaluate the visual and refractive outcomes in cases after sutured scleral fixation of existing subluxated or dislocated acrylic one-piece intraocular lenses(IOLs).METHODS:This study retrospectively enrolled a consecutive series of patients who underwent a surgery of sutured existing subluxated or dislocated IOLs from October 2018 to June *** patients underwent comprehensive preoperative and postoperative ophthalmologic examination,and data were collected including age,sex,surgical indications,best-corrected visual acuity,refractive error,intraocular *** of intraoperative and postoperative surgical complications was ***:A total of 20 consecutive cases were enrolled for analysis with mean final follow-up period 9.8±*** acuity improved from a mean of 0.35(0.46±0.32 logMAR)preoperatively to 0.61(0.21±0.18 logMAR)at the 3-month follow-up(P=0.002).The mean amount of preoperative keratometric astigmatism and total postoperative refractive astigmatism was-1.24±0.80 diopters(D)and-1.42±0.97 D,*** was no statistically significant difference between preoperative and postoperative astigmatism(P=0.156).The mean IOL-induced astigmatism was-0.23±0.53 *** mean spherical equivalent at the 3-month follow-up was-0.1±0.94 *** major complications were noted during the follow-up ***:Surgical techniques using sutured scleral fixation of existing subluxated or dislocated acrylic one-piece IOLs result in favorable visual and refractive outcomes without major complications.

关键词： intraocular lens dislocation intraocular lens subluxation lens dislocation lens subluxation scleral fixation

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Harnessing the power of pericytes and hypoxia-inducible factor-1 to modulate stroke outcome

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Neural Regeneration Research 2024年第3期19卷 473-474页

作者： Omolara O.Ogunshola chih-Chieh Tsao Institute of Veterinary Physiology Vetsuisse FacultyUniversity of ZurichZurichSwitzerland

The human brain has exceedingly high metabolic *** cerebral vasculature has the critical task of providing sufficient blood supply to meet this *** sudden interruption of blood flow to the brain,as observed during ischemic stroke,results in acute neurological injury with devastating consequences-a high rate of adult disability and *** stroke is thus a vascular disorder with a dramatic neurological *** is an urgent need for more effective disease management to combat stroke as current treatment paradigms,focusing on vascular recanalization and neuroprotection,have only limited clinical *** accumulating data suggests successful long-term neuroprotection is unlikely to be achievable without a functional microvascular network,strategies that reduce endothelial dysfunction could be ***,very recent evidence highlighted herein suggests protecting the humble pericyte may be a new approach to reaching this goal.

关键词： consequences exceeding herein

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Virtual Power Plants for Grid Resilience: A Concise Overview of Research and Applications

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 329-343页

作者： Yijing Xie Yichen Zhang Wei-jen Lee Zongli Lin Yacov A.Shamash IEEE Department of Electrical Engineering University of Texas at ArlingtonArlingtonTX 76019 USA Charles L.Brown Department of Electrical and Computer Engineering University of VirginiaCharlottesvilleVA 22904 USA Department of Electrical and Computer Engineering Stony Brook UniversityStony BrookNY 11794 USA

The power grid is undergoing a transformation from synchronous generators(SGs) toward inverter-based resources(IBRs). The stochasticity, asynchronicity, and limited-inertia characteristics of IBRs bring about challenges to grid resilience. Virtual power plants(VPPs) are emerging technologies to improve the grid resilience and advance the transformation. By judiciously aggregating geographically distributed energy resources(DERs) as individual electrical entities, VPPs can provide capacity and ancillary services to grid operations and participate in electricity wholesale markets. This paper aims to provide a concise overview of the concept and development of VPPs and the latest progresses in VPP operation, with the focus on VPP scheduling and control. Based on this overview, we identify a few potential challenges in VPP operation and discuss the opportunities of integrating the multi-agent system(MAS)-based strategy into the VPP operation to enhance its scalability, performance and resilience.

关键词： Climate change renewable energy resources resilience smart grids virtual power plants(VPPs)

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In-Depth Study of Potential-Based Routing and New Exploration of Its Scheduling Integration

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2891-2911页

作者： Jihoon sung Yeunwoong Kyung Department of Electrical Engineering Korea Advanced Institute of Science and TechnologyDaejeon34141Republic of Korea Division of Information&Communication Engineering Kongju National UniversityCheonan31080Republic of Korea

Industrial wireless mesh networks(WMNs)have been widely deployed in various industrial sectors,providing services such as manufacturing process monitoring,equipment control,and sensor data collection.A notable characteristic of industrial WMNs is their distinct traffic pattern,where the majority of traffic flows originate from mesh nodes and are directed towards mesh *** this context,this paper adopts and revisits a routing algorithm known as ALFA(autonomous load-balancing field-based anycast routing),tailored specifically for anycast(one-to-one-of-many)networking in WMNs,where traffic flows can be served through any one of multiple *** essence,the scheme is a hybrid-type routing strategy that leverages the advantages of both back-pressure routing and geographic ***,its novelty lies in being developed by drawing inspiration from another field,specifically from the movement of charges in an electrostatic potential *** on the previous work,this paper explores further in-depth discussions that were not previously described,including a detailed description of the analogy between an electrostatic system and a WMN system based on precise mapping perspectives derived from intensive analysis,as well as discussions on anycast,numerical methods employed in devising the ALFA scheme,its characteristics,and *** is worth noting that this paper addresses these previously unexplored aspects,representing significant contributions compared to previous *** a completely new exploration,a new scheduling strategy is proposed that is compatible with the routing approach by utilizing the potential-based metric not only in routing but also in *** assigns higher medium access priority to links with a larger potential *** simulation results demonstrate the superior performance of the proposed potential-based joint routing and scheduling scheme across various aspects within industrial WMN scenarios.

关键词： Potential-based routing potential differential scheduling industrial wireless mesh networks

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Identifying Brand Consistency by Product Differentiation Using CNN

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 685-709页

作者： Hung-Hsiang Wang chih-Ping Chen Department of Industrial Design National Taipei University of TechnologyTaipeiTaiwan Department of Product Design Ming Chuan UniversityTaoyuanTaiwan

This paper presents a new method of using a convolutional neural network(CNN)in machine learning to identify brand consistency by product appearance *** Experiment 1,we collected fifty mouse devices from the past thirty-five years from a renowned company to build a dataset consisting of product pictures with pre-defined design features of their appearance and *** show that it is a challenge to distinguish periods for the subtle evolution of themouse devices with such traditionalmethods as time series analysis and principal component analysis(PCA).In Experiment 2,we applied deep learning to predict the extent to which the product appearance variation ofmouse devices of various *** investigation collected 6,042 images ofmouse devices and divided theminto the Early Stage and the Late *** show the highest accuracy of 81.4%with the CNNmodel,and the evaluation score of brand style consistency is 0.36,implying that the brand consistency score converted by the CNN accuracy rate is not always perfect in the real *** relationship between product appearance variation,brand style consistency,and evaluation score is beneficial for predicting new product styles and future product style *** addition,the CNN heat maps highlight the critical areas of design features of different styles,providing alternative clues related to the blurred *** study provides insights into practical problems for designers,manufacturers,and marketers in product *** not only contributes to the scientific understanding of design development,but also provides industry professionals with practical tools and methods to improve the design process and maintain brand *** can use these techniques to find features that influence brand ***,capture these features as innovative design elements and maintain core brand values.

关键词： Machine learning product differentiation brand consistency principal component analysis convolutional neural network computer mouse

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