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Performance analysis of combined cycle power plant

Nikhil DEV,Rajesh ATTRI

《能源前沿（英文）》 2015年第9卷第4期页码 371-386 doi: 10.1007/s11708-015-0371-9

摘要： Combined cycle power plants (CCPPs) are in operation with diverse thermodynamic cycle configurations. Assortment of thermodynamic cycle for scrupulous locality is dependent on the type of fuel available and different utilities obtained from the plant. In the present paper, seven of the practically applicable configurations of CCPP are taken into consideration. Exergetic and energetic analysis of each component of the seven configurations is conducted with the help of computer programming tool, i.e., engineering equation solver (EES) at different pressure ratios. For Case 7, the effects of pressure ratio, turbine inlet temperature and ambient relative humidity on the first and second law is studied. The thermodynamics analysis indicates that the exergy destruction in various components of the combined cycle is significantly affected by the overall pressure ratio, turbine inlet temperature and pressure loss in air filter and less affected by the ambient relative humidity.

关键词： first-law second-law exergy destruction components

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分形方法导出改进的牛顿第二定律及万有引力定律

付昱华

《中国工程科学》 2003年第5卷第6期页码 55-58

摘要：

牛顿第二定律及万有引力定律是根据实验结果总结出来的。为了探讨从理论上导出这两个定律的可能性，根据能量守恒定律，给出用变维分形方法针对一个实例（小球沿长斜面滚下）导出改进的牛顿第二定律及万有引力定律的方法。具体给出了适用于实例的常维分形结果：改进的万有引力定律F=-GMm / r^1.99989和改进的牛顿第二定律F=ma^1.01458。

关键词：分形方法牛顿第二定律万有引力定律理论推导

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Exergy losses in premixed flames of dimethyl ether and hydrogen blends

Tongbin ZHAO, Jiabo ZHANG, Dehao JU, Zhen HUANG, Dong HAN

《能源前沿（英文）》 2019年第13卷第4期页码 658-666 doi: 10.1007/s11708-019-0645-8

摘要： A second-law thermodynamic analysis was conducted for stoichiometric premixed dimethyl ether (DME)/hydrogen (H )/air flames at atmospheric pressure. The exergy losses from the irreversibility sources, i.e., chemical reaction, heat conduction and species diffusion, and those from partial combustion products were analyzed in the flames with changed fuel blends. It is observed that, regardless of the fuel blends, chemical reaction contributes most to the exergy losses, followed by incomplete combustion, and heat conduction, while mass diffusion has the least contribution to exergy loss. The results also indicate that increased H substitution decreases the exergy losses from reactions, conduction, and diffusion, primarily because of the flame thickness reduction at elevated H substitution. The decreases in exergy losses by chemical reactions and heat conduction are higher, but the exergy loss reduction by diffusion is slight. However, the exergy losses from incomplete combustion increase with H substitution, because the fractions of the unburned fuels and combustion intermediates, e.g., H and OH radical, increase. The overall exergy losses in the DME/H flames decrease by about 5% with increased H substitution from 0% to 100%.

关键词： second law analysis flame dimethyl ether (DME) hydrogen binary fuels

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—A legal analysis on environmental acts of enterprises in China

DONG Hongwei

《环境科学与工程前沿（英文）》 2007年第1卷第4期页码 434-442 doi: 10.1007/s11783-007-0069-2

摘要： In the environmental protection field of China, due to lower law-breaking cost but higher law-abiding cost , it is a common case that the enterprise chooses to break through the law on purpose. The punishment to the unlawful pr

关键词： law-abiding punishment environmental protection law-breaking enterprise

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Emissions analysis on second generation biodiesel

Yuvarajan Devarajan,Ravi kumar Jayabal,Devanathan Ragupathy,Harish Venu

《环境科学与工程前沿（英文）》 2017年第11卷第1期 doi: 10.1007/s11783-017-0891-0

摘要： CNSBD can be used as a fuel without any modification in existing CI engine. Pentanol reduces HC, CO, NO and Smoke emissions significantly. New and next generation alternative fuel is employed. Blending of CNSBD with pentanol resulted in no separation of phases and found miscible. This work investigates the effect of adding pentanol with biodiesel derived from cashew nut shell on its emissions characteristics is conducted in stationery diesel engine. The main purpose of this work is intended to reduce the emissions by fuelling biodiesel derived from cashew nut shell and the pentanol blends. Cashew nut shell biodiesel is prepared by transesterification process. Oxygenated additive used in the work is Pentanol. The experiment is conducted using four test fuels such as, biodiesel derived from cashew nut shell (CNSBD), a fuel containing 90% cashew nut shell biodiesel and 10% pentanol (CNSBD90P10), a fuel containing 80% cashew nut shell biodiesel and 20% pentanol (CNSBD80P20) and neat diesel. Experimental work concluded that by adding 10% of pentanol to cashew nut shell biodiesel 10.1%, 2.6%, 5.1% and 2.1%reduction in CO, HC, NO and Smoke emissions were observed respectively. Further by fueling with these blends, no modifications in engines were required.

关键词： Pentanol Biodiesel Emissions

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First law-based thermodynamic analysis on Kalina cycle

ZHANG Ying, HE Maogang, JIA Zhen, LIU Xun

《能源前沿（英文）》 2008年第2卷第2期页码 145-151 doi: 10.1007/s11708-008-0021-6

摘要： Based on the first law of thermodynamics, and adopting the Peng-Robinson equation (P-R equation) as the basic equation for the properties of ammonia-water mixtures, a thermodynamic analysis on a single-stage distillation Kalina cycle is presented. A program to calculate the thermodynamic properties of ammonia-water mixtures, and that for calculating the performance of Kalina cycles, were developed, with which the heat-work conversion particulars of Kalina cycles were theoretically calculated. The influences on the cycle performance of key parameters, such as the pressure and temperature at the inlet of the turbine, the back pressure of the turbine, the concentration of the working solution, the concentration of the basic solution and the cycle multiplication ratio, were analyzed.

关键词： ammonia-water P-R single-stage distillation Peng-Robinson pressure

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Controllability analysis of second-ordermulti-agent systemswith directed andweighted interconnection

Di GUO,Rong-hao ZHENG,Zhi-yun LIN,Gang-feng YAN

《信息与电子工程前沿（英文）》 2015年第16卷第10期页码 838-847 doi: 10.1631/FITEE.1500069

摘要： This article investigates the controllability problem of multi-agent systems. Each agent is assumed to be governed by a second-order consensus control law corresponding to a directed and weighted graph. Two types of topology are considered. The first is concerned with directed trees, which represent the class of topology with minimum information exchange among all controllable topologies. A very simple necessary and sufficient condition regarding the weighting scheme is obtained for the controllability of double integrator multi-agent systems in this scenario. The second is concerned with a more general graph that can be reduced to a directed tree by contracting a cluster of nodes to a component. A similar necessary and sufficient condition is derived. Finally, several illustrative examples are provided to demonstrate the theoretical analysis results.

关键词： Multi-agent systems Controllability Directed tree

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UNREDUCED MEGAGAMETOPHYTE FORMATION VIA SECOND DIVISION RESTITUTION CONTRIBUTES TO TETRAPLOID PRODUCTION

《农业科学与工程前沿（英文）》 2021年第8卷第2期

摘要：

Seedless fruits are desirable in the citrus fresh fruit market. Triploid production via diploid × tetraploid interploidy crosses is thought to be the most efficient and widely-used strategy for the breeding of seedless citrus. Although ‘Orah’ mandarin has desirable organoleptic qualities, seeds in the fruits weaken its market competitiveness. To produce new seedless cultivars that are similar to ‘Orah’ mandarin, we performed three 2x × 4x crosses using ‘Orah’ mandarin as the seed parent to regenerate triploid plantlets. A total of 182 triploid and 36 tetraploid plantlets were obtained. By analyzing their genetic origins using nine novel single nucleotide polymorphism (SNP) markers, all of the triploids and tetraploids derived from these three crosses were proven to be hybrids. Also, we demonstrated that 2n megagametophyte formation in ‘Orah’ mandarin result in tetraploid production in these three interploidy crosses. These tetraploid plantlets were genotyped using eight pericentromeric SNP markers and nine centromere distal SNP markers. Based on the genotypes of the 2n megagametophytes, the parental heterozygosity rates in 16 SNP loci and all 2n megagametophytes were less than 50%, indicating that second division restitution was the mechanism underlying 2n megagametophyte formation at both the population and individual levels. These triploid hybrids enrich the germplasm available for seedless breeding. Moreover, the tetraploid hybrids are valuable as parents for ploidy breeding for the production of seedless citrus fruits.

关键词： Citrus / 2n gamete / interploidy hybridization / pericentromeric SNP marker / second division restitution

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High-order phase-field model with the local and second-order max-entropy approximants

Fatemeh AMIRI

《结构与土木工程前沿（英文）》 2019年第13卷第2期页码 406-416 doi: 10.1007/s11709-018-0475-5

摘要： We approximate the fracture surface energy functional based on phase-field method with smooth local maximum entropy (LME) and second-order maximum entropy (SME) approximants. The higher-order continuity of the meshfree methods such as LME and SME approximants allows to directly solve the fourth-order phase-field equations without splitting the fourth-order differential equation into two second-order differential equations. We will first show that the crack surface functional can be captured more accurately in the fourth-order model with smooth approximants such as LME, SME and B-spline. Furthermore, smaller length scale parameter is needed for the fourth-order model to approximate the energy functional. We also study SME approximants and drive the formulations. The proposed meshfree fourth-order phase-field formulation show more stable results for SME compared to LME meshfree methods.

关键词： second-order maximum entropy local maximum entropy second- and fourth-order phase-field models B-spline

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Analysis of nonlinear channel friction inverse problem

CHENG Weiping, LIU Guohua

《结构与土木工程前沿（英文）》 2007年第1卷第2期页码 205-210 doi: 10.1007/s11709-007-0024-0

摘要： Based on the Backus-Gilbert inverse theory, the singular value decomposition (SVD) for general inverse matrices and the optimization algorithm are used to solve the channel friction inverse problem. The resolution and covariance friction inverse model in matrix form is developed to examine the reliability of solutions. Theoretical analyses demonstrate that the convergence rate of the general Newton optimization algorithm is in the second-order. The Wiggins method is also incorporated into the algorithm. Using the method, noise can be suppressed effectively, and the results are close to accurate solutions with proper control parameters. Also, the numerical stability can be improved.

关键词： singular SVD second-order covariance Theoretical

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《网络安全法（草案二次审议稿）》第27条修改建议——以网络服务提供者协助解密义务为中心

崔聪聪,李欲晓,韩松

《中国工程科学》 2016年第18卷第6期页码 34-38 doi: 10.15302/J-SSCAE-2016.06.007

摘要：

网络服务提供者协助解密义务，隐含着公权力（侦查权）与私权利（通信秘密权、隐私权）之间的冲突。用户的非公开信息应该在可控、可追溯基础上，遵循必要性原则和比例原则，综合考虑执法成本，司法机关经由法律确定网络服务提供者履行协助解密义务获取，进而达到社会治理管控、公众安宁生活与网络服务提供者营业自由的综合效益最大化目标，避免落入公权力严重侵犯私权利的情形或者出现政府失效的无序状态。

关键词：协助解密义务必要性原则比例原则可控、可追溯救济措施

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Improving existing “reaching law” for better discrete control of seismically-excited building structures

Zhijun LI, Zichen DENG

《结构与土木工程前沿（英文）》 2009年第3卷第2期页码 111-116 doi: 10.1007/s11709-009-0022-5

摘要： In this paper, a novel “composite reaching law” was explained in details: 1) the equation of discrete motion for a control system; 2) the design of discrete-time variable structure control. In addition, the model of a three-storey shear-type building structure was used to verify the effectiveness of the discrete variable structure control method. The results of numerical example analysis of the model show that the control law can effectively reduce the peak value of seismic response of the building structure and the chattering effect of the control system.

关键词： discrete-time variable structure control composite reaching law chattering effect saturated control law

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高效节能计算的跨层设计：为实现每瓦特电力每秒千万亿次运算 Perspectives

Xiaobo Sharon HU, Michael NIEMIER

《信息与电子工程前沿（英文）》 2018年第19卷第10期页码 1209-1223 doi: 10.1631/FITEE.1800466

摘要：由于基于摩尔定律的器件缩小及其性能增长趋势正在放缓，实现快速和高效节能信息处理的新技术和计算模型越来越被关注。与此同时，越来越多证据表明，对于传统布尔电路和冯诺依曼处理器，超CMOS器件很难与CMOS技术竞争。开发利用新兴器件的独特性能，特别是在非传统电路和架构背景下，具有提供在功率、性能和能力方面数十或百、千倍的改进潜力。为充分发挥超CMOS器件的优势，从器件到电路到体系结架再到算法的跨层设计工作不可或缺。在此背景下，本文研究了嵌入式应用中的高性能神经网络加速器，重点阐述了基于非传统器件技术、电路样式到架构的跨层工作的几种深度神经网络加速器的设计，介绍了应用级基准验证研究工作。讨论表明，跨层设计工作的确可以在实现极大规模高效节能处理方面带来数量级的改进。

关键词：摩尔定律；高效节能技术；神经网络加速器；超CMOS器件

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How did Archimedes discover the law of buoyancy by experiment?

Hidetaka KUROKI

《机械工程前沿（英文）》 2016年第11卷第1期页码 26-32 doi: 10.1007/s11465-016-0368-z

摘要：

After Archimedes and Vitruvius era, for more than 2000 years, it has been believed that the displaced water measurement of golden crown is impossible, and at his Eureka moment, Archimedes discovered the law of buoyancy (Proposition 7 of his principles) and proved the theft of a goldsmith by weighing the golden crown in water.

A previous study showed that a small amount of displaced water was able to be measured with enough accuracy by the introduced method. Archimedes measured the weight of displaced water. He did not find the law of buoyancy but rather specific gravity of things at the moment.

After which, Archimedes continued to measure the specific gravity of various solids and fluids. Through these measurements, he reached the discovery of the law of buoyancy directly by experiment. In this paper, the process to the discovery of Archimedes’ principle (Proposition 5) is presented.

关键词： Archimedes’ principle buoyancy specific gravity Eureka Vitruvius displaced water balance floating body

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Nonlinear analysis of pre-tensioned glass wall facade by stability function with initial imperfection

Siu-Lai CHAN, Yaopeng LIU, Andy LEE,

《结构与土木工程前沿（英文）》 2010年第4卷第3期页码 376-382 doi: 10.1007/s11709-010-0086-2

摘要： Pre-tensioned high strength trusses using alloy steel bar are widely used as glass wall supporting systems because of the high degree of transparency. The breakage of glass panes in this type of system occurs occasionally, likely to be due to error in design and analysis in addition to other factors like glass impurity and stress concentration around opening in a spider system. Most design does not consider the flexibility of supports from finite stiffness of supporting steel or reinforced concrete beams. The resistance of lateral wind pressure of the system makes use of high tension force coupled with the large deflection effect, both of which are affected by many parameters not generally considered in conventional structures. In the design, one must therefore give a careful consideration on various effects, such as support settlement due to live loads and material creep, temperature change, pre-tension force, and wind pressure. It is not uncommon to see many similar glass wall systems fail in the wind load test chambers under a design wind speed. This paper presents a rigorous analysis and design of this type of structural systems used in a project in Hong Kong, China. The stability function with initial curvature is used in place of the cubic function, which is only accurate for linear analysis. The considerations and analysis techniques are believed to be of value to engineers involved in the design of the structural systems behaving nonlinearly.

关键词： tension system glass wall nonlinear analysis pre-tensioning second-order analysis