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Control of peak pressures of an HCCI engine under varying swirl and operating parameters

T. KARTHIKEYA SHARMA,G. AMBA PRASAD RAO,K. MADHU MURTHY

《能源前沿（英文）》 2016年第10卷第3期页码 337-346 doi: 10.1007/s11708-016-0401-2

摘要： The major advantages of homogeneous charge compression ignition (HCCI) are high efficiency in combination with low NO -emissions. However, one of the major challenges with HCCI is the control of higher peak pressures which may damage the engine, limiting the HCCI engine life period. In this paper, an attempt is made to analyze computationally the effect of induction swirl in controlling the peak pressures of an HCCI engine under various operating parameters. A single cylinder 1.6 L reentrant piston bowl diesel engine is chosen. For computational analysis, the ECFM-3Z model of STAR –CD is considered because it is suitable for analyzing the combustion processes in SI and CI engines. As an HCCI engine is a hybrid version of SI and CI engines, the ECFM-3Z model with necessary modifications is used to analyze the peak pressures inside the combustion chamber. The ECFM-3Z model for HCCI mode of combustion is validated with the existing literature to make sure that the results obtained are accurate. Numerical experiments are performed to study the effect of varying properties like speed of the engine, piston bowl geometry, exhaust gas recirculation (EGR) and equivalence ratio under different swirl ratios in controlling the peak pressures inside the combustion chamber. The results show that the swirl ratio has a considerable impact on controlling the peak pressures of HCCI engine. A reduction in peak pressures are observed with a swirl ratio of 4 because of reduced in cylinder temperatures. The combined effect of four operating parameters, i.e., the speed of the engine, piston bowl geometry, EGR, and equivalence ratio with swirl ratios suggest that lower intake temperatures, reentrant piston bowl, higher engine speeds and higher swirl ratios are favorable in controlling the peak pressures.

关键词： HCCI engine ECFM-3Z Swirl ratio peak pressures engine speed piston bowl geometry

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Z-scheme CdS/WO on a carbon cloth enabling effective hydrogen evolution

《能源前沿（英文）》 2021年第15卷第3期页码 678-686 doi: 10.1007/s11708-021-0768-6

摘要： Photocatalytic water splitting for hydrogen (H₂) generation is a potential strategy to solve the problem of energy crisis and environmental deterioration. However, powder-like photocatalysts are difficult to recycle, and the agglomeration of particles would affect the photocatalytic activity. Herein, a direct Z-scheme CdS/WO₃ composite photocatalyst was fabricated based on carbon cloth through a two-step process. With the support of carbon cloth, photocatalysts tend to grow uniformly for further applications. The experimental results showed that the H₂ yield of adding one piece of CdS/WO₃ composite material was 17.28 μmol/h, which was 5.5 times as compared to that of pure CdS-loaded carbon cloth material. A cycle experiment was conducted to verify the stability of the as-prepared material and the result demonstrated that the H₂ generation performance of CdS/WO₃ decreased slightly after 3 cycles. This work provides new ideas for the development of recyclable photocatalysts and has a positive significance for practical applications.

关键词： photocatalysis CdS/WO₃ carbon cloth Z-scheme hydrogen evolution

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Improvement in the synthesis of 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic acid 2-benzothiazolyl

GAO Shihao, SUN Chenghui, ZHAO Xinqi, GAO Changquan

《化学科学与工程前沿（英文）》 2008年第2卷第1期页码 80-84 doi: 10.1007/s11705-008-0017-0

摘要： 2-(5-Amino-1,2,4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic acid 2-benzothiazolyl thioester(III), an important intermediate of the fourth generation cephalosporins, was efficiently synthesized by reacting 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(Z)-methoxyiminoacetic acid (I) with 2,2′-dibenzothiazole disulfide (II) in the presence of triphenylphosphine. Effects of reaction time, temperature, solvents, catalysts and feeding molar ratio on the yield and quality of products were investigated, and an improved procedure suitable for industrial production was established. Using 1,2-dichloroethane as solvent, triphenylphosphine as reducer, and triethylamine as catalyst, (I) : (II) : (triphenylphosphine) = 1.0 : 1.0 : 1.0, the product was obtained at room temperature in 98.1% yield. The purity of the product without further purification is 98.7% determined by HPLC method. This procedure could be a suitable alternative to the traditional processes because of its easy handling, high yield and low cost.

关键词： 5-Amino-1 2 4-thiadiazol-3-yl 1 2-dichloroethane important intermediate 2-benzothiazolyl thioester temperature

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Z源逆变器在异步电动机中的应用

朱红,祝龙记,夏若飞

《中国工程科学》 2014年第16卷第3期页码 86-91

摘要：本文采用IFOC技术来控制异步电机的速度大小，并使用Z源逆变器，即在逆变器主电路前加上一对阻抗（LC）网络，通过控制直通占空比，可以实现升/降压功能、提高异步电机的效率。

关键词： IFOC 异步电机 Z源逆变器

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Exergy analysis of R1234ze(Z) as high temperature heat pump working fluid with multi-stage compression

WANG, R.Z. WANG

《能源前沿（英文）》 2017年第11卷第4期页码 493-502 doi: 10.1007/s11708-017-0510-6

摘要： In this paper, the simulation approach and exergy analysis of multi-stage compression high temperature heat pump (HTHP) systems with R1234ze(Z) working fluid are conducted. Both the single-stage and multi-stage compression cycles are analyzed to compare the system performance with 120°C pressurized hot water supply based upon waste heat recovery. The exergy destruction ratios of each component for different stage compression systems are compared. The results show that the exergy loss ratios of the compressor are bigger than that of the evaporator and the condenser for the single-stage compression system. The multi-stage compression system has better energy and exergy efficiencies with the increase of compression stage number. Compared with the single-stage compression system, the coefficient of performance (COP) improvements of the two-stage and three-stage compression system are 9.1% and 14.6%, respectively. When the waste heat source temperature is 60°C, the exergy efficiencies increase about 6.9% and 11.8% for the two-stage and three-stage compression system respectively.

关键词： multi-stage compression high temperature heat pump heat recovery exergy destruction R1234ze(Z) working fluid

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基于Z数的TODIM与TOPSIS方法 None

Renato A. KROHLING, André G. C. PACHECO, Guilherme A. dos SANTOS

《信息与电子工程前沿（英文）》 2019年第20卷第2期页码 283-291 doi: 10.1631/FITEE.1700434

摘要：提出一种针对多标准决策问题处理Z数的方法。使用模糊数A和B的有序对Z=(A, B)定义Z数，其中A是兴趣变量的语言值，B是A的概率测度语言值。将Z数转化为模糊数，Z-TODIM和Z-TOPSIS分别是模糊TODIM和模糊TOPSIS的直接扩展。将提出的方法应用于两个案例并与使用精确数的标准方法比较，结果证明其可行。

关键词：多标准决策；TODIM；TOPSIS；模糊数；Z数

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快Z-箍缩——有前景的聚变能源新途径

彭先觉,华欣生

《中国工程科学》 2008年第10卷第1期页码 47-53

摘要：

简要介绍了快Z-箍缩的基本概念；综述了快Z-箍缩等离子体研究及其作为高能密度物理与惯性约束聚变（ICF），尤其作为低成本聚变能源研究的最新进展；探讨了快Z-箍缩驱动ICF作为聚变能源可能遇到的技术问题及应用前景。

关键词：快Z-箍缩内爆高能密度物理惯性约束聚变聚变能源

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Z干扰信道下非正则信号的最佳设计策略 Article

Dan LI, Shan WANG, Fang-lin GU

《信息与电子工程前沿（英文）》 2017年第18卷第11期页码 1900-1912 doi: 10.1631/FITEE.1700030

摘要：本文提出一种用于在干扰被视为加性高斯噪声的假设下在Z干扰信道（z-interference channel, Z-IC）上实现非正则高斯信号（IGS）的Pareto边界（可实现速率区域的边界）。

关键词： Z干扰信道；非正则信号；和速率；帕累托边界；协方差；伪协方差

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三维仿生支架平台的刚度和层尺寸对癌细胞分离的影响 Article

张维冠, 刘子玉, 彭慧芝

《工程（英文）》 2021年第7卷第10期页码 1426-1435 doi: 10.1016/j.eng.2020.09.010

摘要：本研究根据精确控制的设计参数（包括刚度、层数和结构布局），开发了三维（3D）仿生支架平台，用于分离鼻咽癌（NPC43）细胞与永生化鼻咽上皮（NP460）细胞。使用这些3D仿生平台进行研究发现，在较硬的双层支架平台[顶层为40/10 μm沟脊/沟槽（R/T）栅格，底层为20/10 μm R/T网格]上，NPC43细胞与NP460细胞的分离效率可达89%

关键词：细胞分离细胞迁移鼻咽癌（NPC） 3D支架平台

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Fire hazard in transportation infrastructure: Review, assessment, and mitigation strategies

Z. NASER

《结构与土木工程前沿（英文）》 2021年第15卷第1期页码 46-60 doi: 10.1007/s11709-020-0676-6

摘要： This paper reviews the fire problem in critical transportation infrastructures such as bridges and tunnels. The magnitude of the fire problem is illustrated, and the recent increase in fire problems in bridges and tunnels is highlighted. Recent research undertaken to address fire problems in transportation structures is reviewed, as well as critical factors governing the performance of those structures. Furthermore, key strategies recommended for mitigating fire hazards in bridges and tunnels are presented, and their applicability to practical situations is demonstrated through a practical case study. Furthermore, research needs and emerging trends for enhancing the “state-of-the-art” in this area are discussed.

关键词： fire hazard bridges tunnels fire resistance mitigation strategies transportation infrastructure

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硅微z轴谐振陀螺仪负电刚度效应分析及实验验证

夏敦柱,周百令,王寿荣

《中国工程科学》 2007年第9卷第8期页码 66-68

摘要：

介绍了在开环工作状态下硅微z轴谐振陀螺仪由于加工工艺缺陷所导致的误差机理。通过对硅微z轴陀螺仪敏感模态的反馈力与谐振频率的关系分析，间接得出了在敏感方向上电负刚度与力矩器所施电压的内在联系，并在实验上进一步验证电刚度效应。这将为下一步闭环控制方案的设计奠定重要基础。

关键词：硅微z轴陀螺仪负电刚度力矩反馈器微机电系统

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非线性因果效应分析中的因果域 Correspondence

王爱国1,刘礼2,杨矫云3,李廉3

《信息与电子工程前沿（英文）》 2022年第23卷第8期页码 1277-1286 doi: 10.1631/FITEE.2200165

摘要：与线性因果相比，非线性因果具有更复杂的特点和内涵。本文主要讨论非线性因果中的若干个问题，并着重强调因果域的概念。本文基于广泛应用的计算模型和方法，围绕非线性因果分析与计算以及因果域的识别问题提出相应观点和建议，并通过几个具体案例揭示非线性因果在处理复杂因果推断问题中的重要性和现实意义。

关键词：非线性因果效应；因果域；z-特异性因果效应；正向因果；负向因果；空因果

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直接驱动Z箍缩的FLTD型脉冲功率源的发展

孙凤举,邱爱慈,曾正中,曾江涛,丛培天

《中国工程科学》 2009年第11卷第11期页码 56-63

摘要：

介绍了快直线型变压器（FLTD）脉冲源的技术特点；概述了美国圣地亚国家实验室与俄罗斯强流电子学研究所合作研制的FLTD－Z模块的新进展，基于FLTD拟重复频率运行的针对聚变能源（IFE）应用的原理性样机Z－POP装置，以及下一代惯性约束核聚变（ICF）和IFE用的指标为6 MV,60 MA/90 MA和100 ns FLTD型直接驱动脉冲源的概念设想

关键词：快Z箍缩直接驱动 FLTD型脉冲加速器高功率脉冲加速器概念设计

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ZnFe₂O₄/BiVO₄ Z-scheme heterojunction for efficient visible-light photocatalytic

《化学科学与工程前沿（英文）》 2023年第17卷第11期页码 1728-1740 doi: 10.1007/s11705-023-2322-z

摘要： A novel Z-scheme ZnFe₂O₄/BiVO₄ heterojunction photocatalyst was successfully synthesized using a convenient solvothermal method and applied in the visible light photocatalytic degradation of ciprofloxacin, which is a typical antibiotic contaminant in wastewater. The heterostructure of as-synthesized catalysts was confirmed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy characterizations. Compared with the single-phase counterparts, ZnFe₂O₄/BiVO₄ demonstrated considerably enhanced photogenerated charge separation efficiencies because of the Z-scheme transfer mechanism of electrons between the composite photocatalysts. Consequently, the 30% ZnFe₂O₄/BiVO₄ catalyst afforded a degradation rate of up to 97% of 20 mg/L ciprofloxacin under 30 min of visible light irradiation with a total organic carbon removal rate of 50%, which is an excellent activity compared with ever reported BiVO₄-based catalysts. In addition, the liquid chromatography-mass spectrometry and quantitative structure-activity relationships model analyses demonstrated that the toxicity of the intermediates was lower than that of the parent ciprofloxacin. Moreover, the as-synthesized ZnFe₂O₄/BiVO₄ heterojunctions were quite stable and could be reused at least four times. This study thus provides a promising Z-scheme heterojunction photocatalyst for the efficient removal and detoxication of antibiotic pollutants from wastewater.

关键词： ZnFe₂O₄/BiVO₄ Z-scheme heterojunction photocatalytic degradation ciprofloxacin

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Upgrading of derived pyrolysis vapors for the production of biofuels from corncobs

Liaoyuan Mao, Yanxin Li, Z. Conrad Zhang

《化学科学与工程前沿（英文）》 2018年第12卷第1期页码 50-58 doi: 10.1007/s11705-017-1685-4

摘要： A bubbling fluidized bed pyrolyzer was integrated with an honeycomb as a catalytic upgrading zone for the conversion of biomass to liquid fuels. In the upgrading zone, zeolite coated ceramic honeycomb (ZCCH) catalysts consisting of ZSM-5 (Si/Al=25) were stacked and N or recycled non-condensable gas was used as a carrier gas. Ground corncob particles were fast pyrolyzed in the bubbling bed using fine sand particles as a heat carrier and the resulting pyrolysis vapors were passed on-line over the catalytic upgrading zone. The influence of carrier gas, temperature, and weight hourly space velocity (WHSV) of catalyst on the oil product properties, distribution and mass balance were studied. Using ZCCH effectively increased the hydrocarbon yield and the heating value of the dry oil, especially in the presence of the recycled noncondensable gas. Even a low usage of zeolite catalyst at WSHV of 180 h was effective in upgrading the pyrolysis oil and other light olefins. The highest hydrocarbon (≥C2) and liquid aromatics yields reached to 14.23 and 4.17 wt-%, respectively. The undesirable products including light oxygenates, furans dramatically decreased in the presence of the ZCCH catalyst.

关键词： corncob monolith upgrading pyrolysis