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Heating energy performance and part load ratio characteristics of boiler staging in an office building

Da Young LEE, Byeong Mo SEO, Yeo Beom YOON, Sung Hyup HONG, Jong Min CHOI, Kwang Ho LEE

《能源前沿（英文）》 2019年 第13卷 第2期   页码 339-353 doi: 10.1007/s11708-018-0596-5

摘要： Commercial buildings account for significant portions of the total building energy in South Korea and thus a variety of research on the boiler operation related to heating energy in office buildings has been carried out thus far. However, most of the researches have been conducted on the boiler itself, i.e., the part load ratio characteristics and the corresponding gas energy consumption patterns are not analyzed in the existing studies. In this study, the part load ratio and the operating characteristics of gas boiler have been analyzed within an office building equipped with the conventional variable air volume system. In addition, the gas consumption among different boiler staging schemes has been comparatively analyzed. As a result, significant portions of total operating hours, heating load and energy consumption has been found to be in a part load ratio range of 0 through 40% and thus energy consumption is significantly affected by boiler efficiency at low part load conditions. This suggests that boiler operation at the part load is an important factor in commercial buildings. In addition, utilizing sequential boiler staging scheme can save a gas usage of about 7%. For annual heating energy saving, applying the sequential control boiler with a 3:7 proportion staging is considered to be the optimal control algorithm for maximum efficiency of boilers.

关键词： EnergyPlus     boiler     part load ratio     gas consumption     office building     boiler staging    

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Improvement of part-load performance of gas turbine by adjusting compressor inlet air temperature and

《能源前沿（英文）》 2022年 第16卷 第6期   页码 1000-1016 doi: 10.1007/s11708-021-0746-z

摘要： A novel adjusting method for improving gas turbine (GT) efficiency and surge margin (SM) under part-load conditions is proposed. This method adopts the inlet air heating technology, which uses the waste heat of low-grade heat source and the inlet guide vane (IGV) opening adjustment. Moreover, the regulation rules of the compressor inlet air temperature and the IGV opening are studied comprehensively to optimize GT performance. A model and calculation method for an equilibrium running line is adopted based on the characteristic curves of the compressor and turbine. The equilibrium running lines calculated through the calculation method involve three part-load conditions and three IGV openings with different inlet air temperatures. The results show that there is an optimal matching relationship between IGV opening and inlet air temperature. For the best GT performance of a given load, the IGV could be adjusted according to inlet air temperature. In addition, inlet air heating has a considerable potential for the improvement of part-load performance of GT due to the increase in compressor efficiency, combustion efficiency, and turbine efficiency as well as turbine inlet temperature, when inlet air temperature is lower than the optimal value with different IGV openings. Further, when the IGV is in a full opening state and an optimal inlet air temperature is achieved by using the inlet air heating technology, GT efficiency and SM can be obviously higher than other IGV openings. The IGV can be left unadjusted, even when the load is as low as 50%. These findings indicate that inlet air heating has a great potential to replace the IGV to regulate load because GT efficiency and SM can be remarkably improved, which is different from the traditional viewpoints.

关键词： inlet air temperature     inlet guide vane (IGV) opening     part-load     equilibrium running line     gas turbine (GT) efficiency     surge margin (SM)    

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Part-load, startup, and shutdown strategies of a solid oxide fuel cell-gas turbine hybrid system

Yang LI, Yiwu WENG, Shilie WENG

《能源前沿（英文）》 2011年 第5卷 第2期   页码 181-194 doi: 10.1007/s11708-011-0149-7

摘要： Current work on the performance of a solid oxide fuel cell (SOFC) and gas turbine hybrid system is presented. Each component model developed and applied is mathematically defined. The electrochemical performance of single SOFC with different fuels is tested. Experimental results are used to validate the SOFC mathematical model. Based on the simulation model, a safe operation regime of the hybrid system is accurately plotted first. Three different part-load strategies are introduced and used to analyze the part-load performance of the hybrid system using the safe regime. Another major objective of this paper is to introduce a suitable startup and shutdown strategy for the hybrid system. The sequences for the startup and shutdown are proposed in detail, and the system responses are acquired with the simulation model. Hydrogen is used instead of methane during the startup and shutdown process. Thus, the supply of externally generated steam is not needed for the reforming reaction. The gas turbine is driven by complementary fuel and supplies compressed air to heat up or cool down the SOFC stack operating temperature. The dynamic simulation results show that smooth cooling and heating of the cell stack can be accomplished without external electrical power.

关键词： solid oxide fuel cell (SOFC)     hybrid system     part-load strategy     startup     shutdown    

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Interaction behavior and load sharing pattern of piled raft using nonlinear regression and LM algorithm-based

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1181-1198 doi: 10.1007/s11709-021-0744-6

摘要： In the recent era, piled raft foundation (PRF) has been considered an emergent technology for offshore and onshore structures. In previous studies, there is a lack of illustration regarding the load sharing and interaction behavior which are considered the main intents in the present study. Finite element (FE) models are prepared with various design variables in a double-layer soil system, and the load sharing and interaction factors of piled rafts are estimated. The obtained results are then checked statistically with nonlinear multiple regression (NMR) and artificial neural network (ANN) modeling, and some prediction models are proposed. ANN models are prepared with Levenberg–Marquardt (LM) algorithm for load sharing and interaction factors through backpropagation technique. The factor of safety (FS) of PRF is also estimated using the proposed NMR and ANN models, which can be used for developing the design strategy of PRF.

关键词： interaction     load sharing ratio     piled raft     nonlinear regression     artificial neural network    

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DSM in an area consisting of residential, commercial and industrial load in smart grid

Balasubramaniyan SARAVANAN

《能源前沿（英文）》 2015年 第9卷 第2期   页码 211-216 doi: 10.1007/s11708-015-0351-0

摘要： With the latest introduction of the demand side management (DSM) in smart grids, the power distribution units are able to modify the load schedules of the consumers. This involves a co-operative interaction of the utility and the consumers so as to achieve customer load modifications in which the customer, utility and society all are benefited. The interaction is performed with the help of the devices known as the smart meter. This paper shows the use of game theory and logical mathematical expressions in order to achieve the objectives. The objectives are to minimize the peak to average ratio (PAR) and the energy cost. The outcome of the game between supplier and customers helps to shape the load profile. The design proposed in this paper is very user-friendly and is based on simple logarithmic programming computations. In this paper, residential, commercial and industrial types of loads are taken into account. A basic 24 h load schedule along with the fluctuating prices at each hour of the day is forecasted by the supplier of the various shiftable and non-shiftable loads and then that schedule is conveyed to the user. The users are encouraged to shift their high load devices to off-peak hours which will not only reduce their electricity costs but also substantially reduce the PAR in the load demand.

关键词： demand side management (DSM)     smart grids     peak to average ratio (PAR)     smart meters and logarithmic price function    

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Heat prices for public buildings in Tianjin

Boyuan HAO,Zhe TIAN,Yan DING,Peng PENG

《能源前沿（英文）》 2016年 第10卷 第3期   页码 249-259 doi: 10.1007/s11708-016-0412-z

摘要： Energy-saving awareness of heat users and heating enterprises can be stimulated by implementing heat metering for public buildings and by establishing scientific and reasonable policies for heat prices in China. In this paper, a two-part heat price for public buildings in Tianjin is introduced, which divides the heat price into a basic part and a metering part. According to the statistical analysis of information collected from two pilot heating enterprises, the specific heat load for public buildings in Tianjin is calculated, and three candidate schemes of heat price are proposed. A simulation of heat cost is also conducted, and the benefits for both heat users and heating enterprises are balanced. Finally, the two-part heat price for public buildings in Tianjin is determined: the basic heat price is recommended to be 20 CNY/m , and the metering heat price is recommended to be 76.10 CNY/GJ. Such a price could be implemented in the initial stage of heat metering for public buildings in Tianjin.

关键词： heat metering     public buildings     two-part heat price     specific heat load    

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掺砂率及初始干密度对改良膨胀土无荷膨胀率影响研究

杨俊,杨志,张国栋,唐云伟,陈红萍

《中国工程科学》 2014年 第16卷 第2期   页码 73-78

摘要：

本文通过室内无荷膨胀率试验，对宜昌市某一级公路改建工程项目路段的膨胀土进行了研究。重点分析了无荷膨胀率与时间、掺砂比例、初始干密度之间的关系，试验研究表明：无荷膨胀变形主要分为快速膨胀、减速膨胀和最终稳定3 个阶段；在初始干密度一定时，风化砂改性土的无荷膨胀率会随着掺砂比例的增大先迅速降低然后缓慢降低，风化砂改性土的无荷膨胀率对较大的掺砂量不敏感；在相同的掺砂比例下，风化砂改性土的无荷膨胀率随着初始干密度的增大会迅速增大，它们之间有很好的线性相关性，膨胀土在进行路基填筑时，控制初始干密度有助于减小其膨胀变形，保证路基填土的稳定性。

关键词： 膨胀土     风化砂     初始干密度     掺砂比例     无荷膨胀率    

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Influence of loading ratio on flat slab connections at elevated temperature: A numerical study

Rwayda Kh. S. AL-HAMD, Martin GILLIE, Safaa Adnan MOHAMAD, Lee S. CUNNINGHAM

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 664-674 doi: 10.1007/s11709-020-0620-9

摘要： For reinforced concrete members subjected to high temperature, the degree of in-service loading, commonly expressed as the loading ratio, can be highly influential on the structural behavior. In particular, the loading ratio may be pivotal in relation to the phenomenon of load-induced thermal strain. Despite its potentially pivotal role, to date, the influence of the loading ratio on both material and structural behavior has not been explored in detail. In practice, real structures experience variation in imposed loading during their service life and it is important to understand the likely response at elevated temperatures across the loading envelope. In this paper, the effect of the loading ratio is numerically investigated at both material and structural level using a validated finite element model. The model incorporates a proposed constitutive model accounting for load-induced thermal strain and this is shown to outperform the existing Eurocode 2 model in terms of accuracy. Using the validated model, the specific case of flats slabs and the associated connections to supporting columns at various loading ratios are explored. For the cases examined, a marked difference in the structural behavior including displacement direction was captured from low to high loading ratios consistent with experimental observations.

关键词： concrete     finite elements     fire     load-induced thermal strain     punching shear    

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Residual stresses in coating-based systems, part I: Mechanisms and analytical modeling

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

《机械工程前沿（英文）》 2007年 第2卷 第1期   页码 1-12 doi: 10.1007/s11465-007-0001-2

摘要： Thin films and multi-layered coatings comprised of different classes of materials are often used for various functional devices. The thermo-mechanical integrity of these systems is becoming a major concern and is strongly related to the residual stresses because of the fabrication processes. In this paper, the sources of the residual stresses in the coating-based systems and the concept of misfit strain were briefly reviewed. Analytical models were developed to predict the residual stresses in multi-layered film structures or coating-based systems using the force and moment balances. In addition, the residual stress distributions in the func tionally and compositionally graded coatings were also analyzed.

关键词： briefly     different     thermo-mechanical integrity     addition     residual    

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Process development for green part printing using binder jetting additive manufacturing

Hadi MIYANAJI, Morgan ORTH, Junaid Muhammad AKBAR, Li YANG

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 504-512 doi: 10.1007/s11465-018-0508-8

摘要：

Originally developed decades ago, the binder jetting additive manufacturing (BJ-AM) process possesses various advantages compared to other additive manufacturing (AM) technologies such as broad material compatibility and technological expandability. However, the adoption of BJ-AM has been limited by the lack of knowledge with the fundamental understanding of the process principles and characteristics, as well as the relatively few systematic design guideline that are available. In this work, the process design considerations for BJ-AM in green part fabrication were discussed in detail in order to provide a comprehensive perspective of the design for additive manufacturing for the process. Various process factors, including binder saturation, in-process drying, powder spreading, powder feedstock characteristics, binder characteristics and post-process curing, could significantly affect the printing quality of the green parts such as geometrical accuracy and part integrity. For powder feedstock with low flowability, even though process parameters could be optimized to partially offset the printing feasibility issue, the qualities of the green parts will be intrinsically limited due to the existence of large internal voids that are inaccessible to the binder. In addition, during the process development, the balanced combination between the saturation level and in-process drying is of critical importance in the quality control of the green parts.

关键词： binder jetting     additive manufacturing     green part     process optimization     process development    

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以东为鉴 秀丽晚成——西部风景园林开发浅议

孟兆祯

《中国工程科学》 2000年 第2卷 第10期   页码 56-58

摘要：

首先我们要站在人类社会生产与自然环境协调的可持续发展的高度着手综合的国土规划，建立从总体到单体的规划设计科学序列。现阶段城市的本质应为人类聚居并藉以生存的生活环境。城市化进程与自然环境间并非针锋相对的破坏关系。城市形象不仅仅是建筑加道路的形象，而是以人工美入自然，将城市和建筑融汇到自然环境中的形象。我们美好的前景是将城市和建筑建在绿色环境中。风景名胜区和城市园林的建设当前仍须将保护自然资源放在首位。要创造特色，从各市的自然环境和人文脉络中捕捉城市风景园林的特色，不要盲目跟风。秀丽山川，大器晚成。扎实积累，功到必成。

关键词： 城市化进程     风景名胜区     城市园林    

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油压极值比与极值比效率

齐茂林

《中国工程科学》 2001年 第3卷 第4期   页码 73-75

摘要：

文章应用基础公式，推导液压系统油压极值比与极值比效率之间的关系式。该式说明，油压极值比越大，极值比效率就越低。提出了油压极值比是可以设计和选择的。

关键词： 油压极值比     极值比效率     液压系统    

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Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

《能源前沿（英文）》 2015年 第9卷 第4期   页码 472-485 doi: 10.1007/s11708-015-0373-7

摘要： It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors (IMs) are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词： isolated hybrid power system (IHPS)     composite load model     static load     dynamic load     induction motor load model     aggregate load    

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Residual stresses in coating-based systems, part II: Optimal designing methodologies

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

《机械工程前沿（英文）》 2007年 第2卷 第2期   页码 125-136 doi: 10.1007/s11465-007-0022-x

摘要： In this part of the work, different cases are studied to illustrate the implementation of the analytical models that have been developed in Part I [Front. Mech. Eng. China, 2007, 2(1): 1 12]. Different topics are involved in the optimal design of coating-based systems. Some essential relations among material properties and dimensions of the coating and substrate and the residual stress variations are reflected. For the multilayered coating-based systems, some optimal design methodologies are proposed, such as the decrease in stress discontinuity at the interface between the adjacent layers, the curvature as a function of the coating thickness, the effect of the interlayer on the residual stress redistribution, and so on. For the single-layered coating-based systems, some typical approximations that are often used to predict the residual stresses in the coating-based system or bilayer structure are corrected. A simplified model for predicting the quenching stress in a coating is also developed.

关键词： function     different     substrate     interlayer     implementation    

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Current progress on internal medicine in China—2006 Part II

YAO Dingkang, ZHU Liang, YU Renqian, MEI Changlin

《医学前沿（英文）》 2007年 第1卷 第4期   页码 343-351 doi: 10.1007/s11684-007-0066-7

摘要： A lot of progress has been made on internal medicine in the past year. Here a great deal of data were collected about internal medicine in China by searching for some most important medicine magazines published in China in 2006. Because there are so many articles on internal medicine, some representative reports were selected and further reviewed. In the part II, a summary of advances made in four branches includes nephrology, hematology, endocrinology and metabolism, rheumatology.

关键词： endocrinology     rheumatology     hematology     nephrology     representative    

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标题 作者 时间 类型 操作

Heating energy performance and part load ratio characteristics of boiler staging in an office building

Da Young LEE, Byeong Mo SEO, Yeo Beom YOON, Sung Hyup HONG, Jong Min CHOI, Kwang Ho LEE

期刊论文

Improvement of part-load performance of gas turbine by adjusting compressor inlet air temperature and

期刊论文

Part-load, startup, and shutdown strategies of a solid oxide fuel cell-gas turbine hybrid system

Yang LI, Yiwu WENG, Shilie WENG

期刊论文

Interaction behavior and load sharing pattern of piled raft using nonlinear regression and LM algorithm-based

期刊论文

DSM in an area consisting of residential, commercial and industrial load in smart grid

Balasubramaniyan SARAVANAN

期刊论文

Heat prices for public buildings in Tianjin

Boyuan HAO,Zhe TIAN,Yan DING,Peng PENG

期刊论文

掺砂率及初始干密度对改良膨胀土无荷膨胀率影响研究

杨俊,杨志,张国栋,唐云伟,陈红萍

期刊论文

Influence of loading ratio on flat slab connections at elevated temperature: A numerical study

Rwayda Kh. S. AL-HAMD, Martin GILLIE, Safaa Adnan MOHAMAD, Lee S. CUNNINGHAM

期刊论文

Residual stresses in coating-based systems, part I: Mechanisms and analytical modeling

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

期刊论文

Process development for green part printing using binder jetting additive manufacturing

Hadi MIYANAJI, Morgan ORTH, Junaid Muhammad AKBAR, Li YANG

期刊论文

以东为鉴 秀丽晚成——西部风景园林开发浅议

孟兆祯

期刊论文

油压极值比与极值比效率

齐茂林

期刊论文

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

期刊论文

Residual stresses in coating-based systems, part II: Optimal designing methodologies

ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou

期刊论文

Current progress on internal medicine in China—2006 Part II

YAO Dingkang, ZHU Liang, YU Renqian, MEI Changlin

期刊论文