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An indirect evaporative chiller

Xiaoyun XIE, Yi JIANG,

《能源前沿（英文）》 2010年 第4卷 第1期   页码 66-76 doi: 10.1007/s11708-010-0021-1

摘要： A novel indirect evaporative chiller driven by outdoor dry air to produce cold water as the cooling source for air conditioning systems is introduced, and the principle and the structure of the chiller is presented. The cold water can be produced almost reversibly under ideal working conditions, with its temperature infinitely close to the dew point temperature of the inlet air. The key components of the chiller are an air cooler and a padding tower. To improve the heat transfer performance inside the chiller, a quasi-countercurrent air cooler was designed; a subsection linear method was used for the mathematical model of the padding tower. The first indirect evaporative chiller, designed and developed in 2005, has been in use in Kairui Building, a big hotel in Shihezi, Xinjiang Autonomous Region. The tested temperature of the water produced is below the wet bulb temperature of outdoor air and reached the average value of the dew point temperature and the wet bulb temperature of outdoor air. As the running components are only pumps and fans, the COP (cooling energy for room divided by power cost) of this chiller is high, and the drier the outdoor air, the higher COP the chiller obtained. Since no CFCs are used in this chiller, it would not cause any pollution to the aerosphere. Finally, the application prospect of the indirect evaporative chiller in the world is presented.

关键词： indirect evaporative chiller     dry air     dew point temperature    

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Room temperature liquid metal: its melting point, dominating mechanism and applications

Junheng FU, Chenglin ZHANG, Tianying LIU, Jing LIU

《能源前沿（英文）》 2020年 第14卷 第1期   页码 81-104 doi: 10.1007/s11708-019-0653-8

摘要： The room temperature liquid metal (LM) is recently emerging as a new class of versatile materials with fascinating characteristics mostly originated from its simultaneous metallic and liquid natures. The melting point is a typical parameter to describe the peculiarity of LM, and a pivotal factor to consider concerning its practical applications such as phase change materials (PCMs) and advanced thermal management. Therefore, the theoretical exploration into the melting point of LM is an essential issue, which can be of special value for the design of new LM materials with desired properties. So far, some available strategies such as molecular dynamics (MD) simulation and classical thermodynamic theory have been applied to perform correlative analysis. This paper is primarily dedicated to performing a comprehensive overview regarding typical theoretical strategies on analyzing the melting points. It, then, presents evaluations on several factors like components, pressure, size and supercooling that may be critical for melting processes of liquid metal. After that, it discusses applications associated with the characteristic of low melting points of LM. It is expected that a great many fundamental and practical works are to be conducted in the coming future.

关键词： melting point     liquid metal     crystal     thermodynamics     molecular dynamics    

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Impacts of CO2 and H2S on the risk of hydrate formation during pipeline transport of natural gas

Solomon A. Aromada, Bjørn Kvamme

《化学科学与工程前沿（英文）》 2019年 第13卷 第3期   页码 616-627 doi: 10.1007/s11705-019-1795-2

摘要： Evaluation of maximum content of water in natural gas before water condenses out at a given temperature and pressure is the initial step in hydrate risk analysis during pipeline transport of natural gas. The impacts of CO and H S in natural gas on the maximum mole-fractions of water that can be tolerated during pipeline transport without the risk of hydrate nucleation has been studied using our novel thermodynamic scheme. Troll gas from the North Sea is used as a reference case, it contains very negligible amount of CO and no H S. Varying mole-fractions of CO and H S were introduced into the Troll gas, and the effects these inorganic impurities on the water tolerance of the system were evaluated. It is observed that CO does not cause any distinguishable impact on water tolerance of the system, but H S does. Water tolerance decreases with increase in concentration of H S. The impact of ethane on the system was also investigated. The maximum mole-fraction of water permitted in the gas to ensure prevention of hydrate formation also decreases with increase in the concentration of C H like H S. H S has the most impact, it tolerates the least amount of water among the components studied.

关键词： hydrate     hydrogen Sulphide     CO2     dew point     pipeline    

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Key point selection in large-scale FBG temperature sensors for thermal error modeling of heavy-duty CNC

Jianmin HU, Zude ZHOU, Quan LIU, Ping LOU, Junwei YAN, Ruiya LI

《机械工程前沿（英文）》 2019年 第14卷 第4期   页码 442-451 doi: 10.1007/s11465-019-0543-0

摘要： Thermal error is one of the main factors that influence the machining accuracy of computer numerical control (CNC) machine tools. It is usually reduced by thermal error compensation. Temperature field monitoring and key temperature measurement point (TMP) selection are the bases of thermal error modeling and compensation for CNC machine tools. Compared with small- and medium-sized CNC machine tools, heavy-duty CNC machine tools require the use of more temperature sensors to measure their temperature comprehensively because of their larger size and more complex heat sources. However, the presence of many TMPs counteracts the movement of CNC machine tools due to sensor cables, and too many temperature variables may adversely influence thermal error modeling. Novel temperature sensors based on fiber Bragg grating (FBG) are developed in this study. A total of 128 FBG temperature sensors that are connected in series through a thin optical fiber are mounted on a heavy-duty CNC machine tool to monitor its temperature field. Key TMPs are selected using these large-scale FBG temperature sensors by using the density-based spatial clustering of applications with noise algorithm to reduce the calculation workload and avoid problems in the coupling of TMPs for thermal error modeling. Back propagation neural network thermal error prediction models are established to verify the performance of the proposed TMP selection method. Results show that the number of TMPs is reduced from 128 to 5, and the developed model demonstrates good prediction effects and strong robustness under different working conditions of the heavy-duty CNC machine tool.

关键词： thermal error     heavy-duty CNC machine tools     FBG     key TMPs     prediction model    

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Effect of soil crust on evaporation and dew deposition in Mu Us sandy land, China

SUN Yongliang, LI Xiaoyan, XU Heye, YANG Zhipeng, TANG Jia, ZHANG Xiaoying

《环境科学与工程前沿（英文）》 2008年 第2卷 第4期   页码 480-486 doi: 10.1007/s11783-008-0034-8

摘要： The development of soil crust on sandy land may affect the surface hydrological process. This paper investigates the process of evaporation and dew deposition influenced by different soil surface types which were dominated by sand, primitive biotic crust, and advanced biotic crust, respectively, in the south fringe of Mu Us sandy land in Northwest China from July to September of 2006. The experimental results indicate that the advanced biotic crust could increase evaporation and dew deposition compared to the primitive biotic crust and bare sand although the differences between them were not significant. The average evaporation from advanced biotic crust, primitive biotic crust and sand was 6.8, 6.6, and 6.5 mm/d, respectively, and water content is around 16.2 % in the condition of initially identical soil. The average dew amount on advanced biotic crust was 0.116 mm/d with extreme 0.05 and 0.24 mm/d. The average values on primitive biotic crust and sand were 0.105 and 0.101 mm/d, respectively, with extreme 0.04 and 0.21 mm/d for both treatments. Also, the dew deposition on advanced biotic crust seemed stable and might rest for a longer time than that on primitive biotic crust and sand. The results suggest that the advanced biotic crust possibly facilitates evaporation and dew deposition. Therefore, the development of biotic crust may potentially enhance the hydrological circulation in the upper sand layer in sandy land.
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Analysis of energy saving optimization of campus buildings based on energy simulation

Dingding TONG, Jing ZHAO

《能源前沿（英文）》 2013年 第7卷 第3期   页码 388-398 doi: 10.1007/s11708-013-0273-7

摘要： The energy consumption of campus buildings has specific characteristics, because of the concentrated distribution of people’s working time and locations that change in line with distinct seasonal features. The traditional energy system design and operation for campus buildings is only based on the constant room temperature, such as 25°C in summer and 18°C in winter in China, not taking into consideration the real heating or cooling load characteristics of campus buildings with different functions during the whole day and whole year, which usually results in a lot of energy waste. This paper proposes to set different set-point temperatures in different operation stages of public and residential campus buildings to reduce the heating and cooling design load for energy station and total campus energy consumption for annual operation. Taking a campus under construction in Tianjin, China as an example, two kinds of single building models were established as the typical public building and residential building models on the campus. Besides, the models were simulated at both set-point room temperature and constant room temperature respectively. The comparison of the simulation results showed that the single building energy saving method of the peak load clipping could be used for further analysis of the annual energy consumption of campus building groups. The results proved that the strategy of set-point temperature optimization could efficiently reduce the design load and energy consumption of campus building groups.

关键词： campus buildings     set-point temperature     energy simulation     energy saving optimization    

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Liquid metal as energy transportation medium or coolant under harsh environment with temperature below

Yunxia GAO, Lei WANG, Haiyan LI, Jing LIU

《能源前沿（英文）》 2014年 第8卷 第1期   页码 49-61 doi: 10.1007/s11708-013-0285-3

摘要： The current highly integrated electronics and energy systems are raising a growing demand for more sophisticated thermal management in harsh environments such as in space or some other cryogenic environment. Recently, it was found that room temperature liquid metals (RTLM) such as gallium or its alloys could significantly reduce the electronics temperature compared with the conventional coolant, like water, oil or more organic fluid. However, most of the works were focused on RTLM which may subject to freeze under low temperature. So far, a systematic interpretation on the preparation and thermal properties of liquid metals under low temperature (here defined as lower than 0°C) has not yet been available and related applications in cryogenic field have been scarce. In this paper, to promote the research along this important direction and to overcome the deficiency of RTLM, a comprehensive evaluation was proposed on the concept of liquid metal with a low melting point below zero centigrade, such as mercury, alkali metal and more additional alloy candidates. With many unique virtues, such liquid metal coolants are expected to open a new technical frontier for heat transfer enhancement, especially in low temperature engineering. Some innovative ways for making low melting temperature liquid metal were outlined to provide a clear theoretical guideline and perform further experiments to discover new materials. Further, a few promising applied situations where low melting temperature liquid metals could play irreplaceable roles were detailed. Finally, some main factors for optimization of low temperature coolant were summarized. Overall, with their evident merits to meet various critical requirements in modern advanced energy and power industries, liquid metals with a low melting temperature below zero centigrade are expected to be the next-generation high-performance heat transfer medium in thermal managements, especially in harsh environment in space.

关键词： liquid metal     cryogenics     low melting point     thermal management     aircraft     liquid cooling     space exploration    

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STRENGTHENING NON-POINT SOURCE POLLUTION CONTROL TO PROMOTE AGRICULTURAL GREEN DEVELOPMENT

《农业科学与工程前沿（英文）》 2023年 第10卷 第4期   页码 503-509 doi: 10.15302/J-FASE-2023528

摘要：

STRENGTHENING NON-POINT SOURCE POLLUTION CONTROL TO PROMOTE AGRICULTURAL GREEN DEVELOPMENT

关键词： GREEN     AGRICULTURAL     PROMOTE     POLLUTION     SOURCE     DEVELOPMENT     POINT     STRENGTHENING     CONTROL    

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Trajectory planning of mobile robots using indirect solution of optimal control method in generalized point-to-point

M. NAZEMIZADEH, H. N. RAHIMI, K. AMINI KHOIY

《机械工程前沿（英文）》 2012年 第7卷 第1期   页码 23-28 doi: 10.1007/s11465-012-0304-9

摘要：

This paper presents an optimal control strategy for optimal trajectory planning of mobile robots by considering nonlinear dynamic model and nonholonomic constraints of the system. The nonholonomic constraints of the system are introduced by a nonintegrable set of differential equations which represent kinematic restriction on the motion. The Lagrange’s principle is employed to derive the nonlinear equations of the system. Then, the optimal path planning of the mobile robot is formulated as an optimal control problem. To set up the problem, the nonlinear equations of the system are assumed as constraints, and a minimum energy objective function is defined. To solve the problem, an indirect solution of the optimal control method is employed, and conditions of the optimality derived as a set of coupled nonlinear differential equations. The optimality equations are solved numerically, and various simulations are performed for a nonholonomic mobile robot to illustrate effectiveness of the proposed method.

关键词： mobile robot     trajectory planning     nonlinear dynamic     optimal control    

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Toward autonomous mining: design and development of an unmanned electric shovel via point cloud-based

《机械工程前沿（英文）》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0686-2

摘要： With the proposal of intelligent mines, unmanned mining has become a research hotspot in recent years. In the field of autonomous excavation, environmental perception and excavation trajectory planning are two key issues because they have considerable influences on operation performance. In this study, an unmanned electric shovel (UES) is developed, and key robotization processes consisting of environment modeling and optimal excavation trajectory planning are presented. Initially, the point cloud of the material surface is collected and reconstructed by polynomial response surface (PRS) method. Then, by establishing the dynamical model of the UES, a point to point (PTP) excavation trajectory planning method is developed to improve both the mining efficiency and fill factor and to reduce the energy consumption. Based on optimal trajectory command, the UES performs autonomous excavation. The experimental results show that the proposed surface reconstruction method can accurately represent the material surface. On the basis of reconstructed surface, the PTP trajectory planning method rapidly obtains a reasonable mining trajectory with high fill factor and mining efficiency. Compared with the common excavation trajectory planning approaches, the proposed method tends to be more capable in terms of mining time and energy consumption, ensuring high-performance excavation of the UES in practical mining environment.

关键词： autonomous excavation     unmanned electric shovel     point cloud     excavation trajectory planning    

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DITCHES AND PONDS CAN BE THE SOURCES OR SINKS OF NON-POINT SOURCE POLLUTION: OBSERVATIONS IN AN UPLAND

《农业科学与工程前沿（英文）》 2023年 第10卷 第4期   页码 607-626 doi: 10.15302/J-FASE-2023517

摘要：

As the common features of agroecosystems, ditches and ponds benefit the irrigation and drainage, as well as intercepting non-point source pollutants. However, most ditch-pond studies have been conducted in lowland areas. To test this source-sink assumption in upland areas, this study made observations on the ecological function of the ditch and pond system in a typical catchment in China. First, the changes in ponds in the catchment were analyzed using high-resolution remote sensing data. Then, the migration of agricultural pollutants in ditches and ponds were analyzed by field sampling and laboratory detection. The results showed that over the past 15 years the length of ditches in the catchment and the number of small ponds (< 500 m2) have increased by 32% and 75%, respectively. The rate of change in nutrient concentrations in the ditches and ponds were mostly from −20% to 20%, indicating ditches and ponds can be both sources and sinks for agricultural pollutants. Lastly, the contributing factors were explored and it was found that ditches and ponds are important sinks in dry season. However, during the rainy season, ditches and ponds become sources of pollutants, with the rapid drainage of ditches and the overflow of ponds in upland areas. The results of this study revealed that the ditches and ponds could be used for ecological engineering in upland catchments to balance drainage and intercept pollutants.

关键词： ditches     ponds     non-point source pollution     mountainous areas     nitrogen     phosphorus    

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A multiscale-contour-based interpolation framework for generating a time-varying quasi-dense point cloud

Chu-hua HUANG,Dong-ming LU,Chang-yu DIAO

《信息与电子工程前沿（英文）》 2016年 第17卷 第5期   页码 422-434 doi: 10.1631/FITEE.1500316

摘要： To speed up the reconstruction of 3D dynamic scenes in an ordinary hardware platform, we propose an efficient framework to reconstruct 3D dynamic objects using a multiscale-contour-based interpolation from multi-view videos. Our framework takes full advantage of spatio-temporal-contour consistency. It exploits the property to interpolate single contours, two neighboring contours which belong to the same model, and two contours which belong to the same view at different times, corresponding to point-, contour-, and model-level interpolations, respectively. The framework formulates the interpolation of two models as point cloud transport rather than non-rigid surface deformation. Our framework speeds up the reconstruction of a dynamic scene while improving the accuracy of point-pairing which is used to perform the interpolation. We obtain a higher frame rate, spatio-temporal-coherence, and a quasi-dense point cloud sequence with color information. Experiments with real data were conducted to test the efficiency of the framework.

关键词： Multi-view video     Free-viewpoint video     Point-pair     Multiscale-contour-based interpolation     Spatio-temporal-contour     Consistency     Time-varying point cloud sequence    

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Ceramic water filter for point-of-use water treatment in developing countries: Principles, challenges

Haiyan Yang, Shangping Xu, Derek E. Chitwood, Yin Wang

《环境科学与工程前沿（英文）》 2020年 第14卷 第5期 doi: 10.1007/s11783-020-1254-9

摘要： • CWF is a sustainable POU water treatment method for developing areas. • CWF manufacturing process is critical for its filtration performance. • Simultaneous increase of flow rate and pathogen removal is a challenge. • Control of pore size distribution holds promises to improve CWF efficiency. • Novel coatings of CWFs are a promising method to improve contaminant removal. Drinking water source contamination poses a great threat to human health in developing countries. Point-of-use (POU) water treatment techniques, which improve drinking water quality at the household level, offer an affordable and convenient way to obtain safe drinking water and thus can reduce the outbreaks of waterborne diseases. Ceramic water filters (CWFs), fabricated from locally sourced materials and manufactured by local labor, are one of the most socially acceptable POU water treatment technologies because of their effectiveness, low-cost and ease of use. This review concisely summarizes the critical factors that influence the performance of CWFs, including (1) CWF manufacturing process (raw material selection, firing process, silver impregnation), and (2) source water quality. Then, an in-depth discussion is presented with emphasis on key research efforts to address two major challenges of conventional CWFs, including (1) simultaneous increase of filter flow rate and bacterial removal efficiency, and (2) removal of various concerning pollutants, such as viruses and metal(loid)s. To promote the application of CWFs, future research directions can focus on: (1) investigation of pore size distribution and pore structure to achieve higher flow rates and effective pathogen removal by elucidating pathogen transport in porous ceramic and adjusting manufacture parameters; and (2) exploration of new surface modification approaches with enhanced interaction between a variety of contaminants and ceramic surfaces.

关键词： Point-of-use water treatment     Ceramic water filter     Bacterial removal     Surface modification     Water quality    

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Artificial bee colony optimization for economic dispatch with valve point effect

Yacine LABBI,Djilani Ben ATTOUS,Belkacem MAHDAD

《能源前沿（英文）》 2014年 第8卷 第4期   页码 449-458 doi: 10.1007/s11708-014-0316-8

摘要： In recent years, various heuristic optimization methods have been proposed to solve economic dispatch (ED) problem in power systems. This paper presents the well-known power system ED problem solution considering valve-point effect by a new optimization algorithm called artificial bee colony (ABC). The proposed approach has been applied to various test systems with incremental fuel cost function, taking into account the valve-point effects. The results show that the proposed approach is efficient and robust when compared with other optimization algorithms reported in literature.

关键词： artificial bee colony (ABC) algorithm     economic dispatch (ED)     valve-point effect     optimization    

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Removal of non-point pollutants from bridge runoff by a hydrocyclone using natural water head

Jianghua YU, Yeonseok KIM, Youngchul KIM

《环境科学与工程前沿（英文）》 2013年 第7卷 第6期   页码 886-895 doi: 10.1007/s11783-012-0449-0

摘要： A hydrocyclone using natural water head provided by bridge was operated for the treatment of stormwater runoff. The hydrocyclone was automatically controlled using electronic valve which is connected to a pressure meter. Normally the hydrocyclone was open during dry days, but it was closed after the capture of the first flush. The results indicated that the average pressure and the flow rate were directly affected by the rainfall intensity. The pressure head was more than 2 m when the rainfall intensity was above 5 mm·h . The percentage volume of underflow with high solids concentration decreased as the pressure and flow rate increased, but the percentage volume of overflow with almost no solids showed the opposite behavior. The total suspended solids (TSS) concentration ratio between the overflow and inflow (TSS /TSS ) decreased as a function of the operational pressure, while the corresponding ratio of underflow to inflow (TSS /TSS ) increased. The TSS separation efficiency was evaluated based on a mass balance. It ranged from 25% to 99% with the pressure head ranging from 1.4 to 9.7 m, and it was proportional to pressure and flow rate. Normally, the efficiency was more than 50% when the pressure was higher than 2 m. The analysis of the water budget indicated that around 13% of the total runoff was captured by the hydrocyclone as a first flush, and this runoff was separated as underflow and overflow with the respective percentage volumes of 29% and 71%. The pollutants budget was also examined based on a mass balance. The results showed that the percentage of TSS, chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) in underflow were 73%, 59%, 7.6%, and 49%, respectively. Thus, it can be concluded that the hydrocyclone worked well. It separated the first flush as solids-concentrated underflow and solids-absent overflow, and effectively reduced the runoff volume needing further treatment. Finally, four types of optional post treatment design are presented and compared.

关键词： first flush     hydrocyclone     non-point pollution     removal efficiency     stormwater runoff    

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标题 作者 时间 类型 操作

An indirect evaporative chiller

Xiaoyun XIE, Yi JIANG,

期刊论文

Room temperature liquid metal: its melting point, dominating mechanism and applications

Junheng FU, Chenglin ZHANG, Tianying LIU, Jing LIU

期刊论文

Impacts of CO2 and H2S on the risk of hydrate formation during pipeline transport of natural gas

Solomon A. Aromada, Bjørn Kvamme

期刊论文

Key point selection in large-scale FBG temperature sensors for thermal error modeling of heavy-duty CNC

Jianmin HU, Zude ZHOU, Quan LIU, Ping LOU, Junwei YAN, Ruiya LI

期刊论文

Effect of soil crust on evaporation and dew deposition in Mu Us sandy land, China

SUN Yongliang, LI Xiaoyan, XU Heye, YANG Zhipeng, TANG Jia, ZHANG Xiaoying

期刊论文

Analysis of energy saving optimization of campus buildings based on energy simulation

Dingding TONG, Jing ZHAO

期刊论文

Liquid metal as energy transportation medium or coolant under harsh environment with temperature below

Yunxia GAO, Lei WANG, Haiyan LI, Jing LIU

期刊论文

STRENGTHENING NON-POINT SOURCE POLLUTION CONTROL TO PROMOTE AGRICULTURAL GREEN DEVELOPMENT

期刊论文

Trajectory planning of mobile robots using indirect solution of optimal control method in generalized point-to-point

M. NAZEMIZADEH, H. N. RAHIMI, K. AMINI KHOIY

期刊论文

Toward autonomous mining: design and development of an unmanned electric shovel via point cloud-based

期刊论文

DITCHES AND PONDS CAN BE THE SOURCES OR SINKS OF NON-POINT SOURCE POLLUTION: OBSERVATIONS IN AN UPLAND

期刊论文

A multiscale-contour-based interpolation framework for generating a time-varying quasi-dense point cloud

Chu-hua HUANG,Dong-ming LU,Chang-yu DIAO

期刊论文

Ceramic water filter for point-of-use water treatment in developing countries: Principles, challenges

Haiyan Yang, Shangping Xu, Derek E. Chitwood, Yin Wang

期刊论文

Artificial bee colony optimization for economic dispatch with valve point effect

Yacine LABBI,Djilani Ben ATTOUS,Belkacem MAHDAD

期刊论文

Removal of non-point pollutants from bridge runoff by a hydrocyclone using natural water head

Jianghua YU, Yeonseok KIM, Youngchul KIM

期刊论文