Optimal synthesis of multi-plant heat exchanger networks considering both direct and indirect methods

Heat exchanger networks(HENs)in separated plants can be simultaneously synthesized through process streams directly or intermediate fluids indirectly.However,the direct and indirect methods are studied separately in most existing researches.As the result,conventional designs are probably suboptimal,because optimal solutions may call for hybrid approach wherein direct and indirect integration methods are used synchronously.To circumvent this drawback aforementioned,we propose in this research a novel methodology to synthesize multi-plant HENs considering both direct and indirect approaches.The methodology employs a novel superstructure covering most potential topologies for both interplant and intra-plant heat integration.We also take into account multiple kinds of intermediate fluids for indirect integration and this has not been fully addressed in previous research.A mixed-integer nonlinear programming(MINLP)is formulated to optimize multi-plant HENs involving indirect and direct methods.One example from existing literature and one industrial problem are solved to demonstrate the methodology’s capability.

MODELS OF THE SPATIAL EVOLUTION OF MULTI-PLANT ENTERPRISES

Since the 1970s, the studies on the geography of enterprise have become increasingly concerned with the spatial evolution of an enterprises in the West developed countries. However, little attention has so far been given to the spatial evolution of an enterprise in China. With China's ongoing economy and political reforms, a number of fundamental changes of enterprise behavior have occurred. These changes have certainly important influences on the evolution of industrial location. Therefore, there is a need for examining the spatial evolution of an enterprise in China. The purpose of the paper is to review the mapjor models of both the growth,and associated spatial evolution of an enterprise, with an illustrative case study of the HeaVy Automobile Enterprise Group of China. The paper is organized by three parts. The first examines the spoilal groWth and location adjustment of multi-plant enterprise. The second reviews mapjor models of the spatial evolution of an enterprise. And the third analyzes the spatial evolution, over a period of time, of a representative sample of the Heavy Automobile Enterprise Group of China, and illustrates the findings with case studies. It is suggested that the models of spatial evolution of an enterprise would provide more evidence about micro-mechanism for evolution of micro- regional economic systems.

A Comparison of Two Macroinvertebrate Multi-Plate Sampling Methods to Inform Great Lakes Monitoring and Remediation Efforts

Hester-Dendy (HD) multi-plate samplers have been widely used by state and federal government agencies for bioassessment of water quality through use of macroinvertebrate community data. To help guide remediation and restoration efforts at the Niagara River Great Lakes Area of Concern site, a multi-agency study was conducted in 2014 to assess the contribution of seven major urban tributaries on the US side of the river toward the impairment of the Niagara River. As part of this study, macroinvertebrate communities were sampled using two co-located versions of HD samplers: one version used by the New York State Department of Environmental Conservation (NYSDEC) and another by the US Environmental Protection Agency Office of Research and Development. Samplers were deployed in tributaries in highly developed watersheds with high percent impervious surface. The two sampling methods varied in terms of number and size of plates, between-plate spacing, and deployment method. Comparison of the similarity/grouping of communities with multivariate ordination techniques, Nonmetric Multidimensional Scaling and Multi-Response Permutation Procedure, showed that both methods were able to detect differences in communities at stations, despite some grouping by month and method. The indices and metrics derived from the two HD methods were found to give comparable but not identical assessments of water quality. Despite their differences, the methods were robust with respect to water quality categories derived from indices used nationally (HBI) and by NY state (BAP). For the common richness metrics, total taxa and EPT richness, there was no statistical difference between means from 3 samplings. Some metrics, especially percent tolerant collector-gatherer individuals, did show significant differences at certain stations. Indicator Species Analysis showed some taxa associated with each method. The observed community differences were thought mostly due to the difference in sampler deployment position. .

新能源多厂共站关口计量与自动化结算系统设计

现有技术中通常存在多个新能源发电厂使用同一个升压站而导致共站监控能力滞后等问题。为更好地监测共站的运行状态,设计了新能源多厂共站关口计量与自动化结算系统,并融入云计算技术进行电力数据的存储和处理。使用关口计量装置和采集终端完成实时数据采集。使用STM32F103RB单片机对关口计量监控装置运行状态进行计量。计量模块使用RN8302集成处理器,并设计有抗干扰模块和滤波网络。使用滑动滤波法和离散小波去噪法对输出的直流信号进行滤波处理,以加密方式提高计量保密程度。基于改进小波去噪的电能计量方法提高计量能力。试验结果表明,计量误差最低为0.11%。该系统的滤波效果较好,重构信号波形较紧密。

Temperature Distributions in Single Cell of Polymer Electrolyte Fuel Cell Simulated by an 1D Multi-plate Heat-Transfer Model and a 3D Numerical Simulation Model

The purpose of this study is to verify an 1D multi-plate heat-transfer model estimating the temperature distribution on the interface between polymer electrolyte membrane and catalyst layer at cathode in single cell of polymer electrolyte fuel cell, which is named as reaction surface in this study, with a 3D numerical simulation model solving many governing equations on the coupling phenomena in the cell. The results from both models/simulations agreed well. The effects of initial operation temperature, flow rate, and relative humidity of supply gas on temperature distribution on the reaction surface were also investigated. It was found in both 1D and 3D simulations that, the temperature rise （i.e., Treact-Tini） of the reaction surface from initial operation temperature at 70℃ was higher than that at 80℃ irrespective of flow rate of supply gas. The effect of relative humidity of supply gas on Treact- Tini near the inlet of the cell was small. Compared to the previous studies conducted under the similar operation conditions, the Treact - Tini calculated by 1D multi-plate heat-transfer model in this study as well as numerical simulation using 3D model was reasonable.

预言二十一世纪

预言二十一世纪金耀基美国历史学家保罗·肯尼迪（ＰａｕｌＫｅｎｎｅｄｙ）于１９８７年出版《世界强权的兴衰》（ＴｈｅＲｉｓｅａｎｄＦａＩｌｏｆｔｈｅＧｒｅａｔＰｏｗｅｒｓ），洛阳纸贵，名噪一时，当时在全美畅销书榜上名列前茅。由于肯尼迪谈到美国跨进２１世纪...

Allocation and Scheduling of Network Resource for Multiple Control Applications in SDN

The network resource allocation in SDN for control applications is becoming a key problem in the near future because of the conflict between the need of the flow-level flexibility control and the limited capacity of flow table.Based on the analysis of the difference of the definition of network resource between SDN and traditional IP network,the idea of the integrated allocation of link bandwidth and flow table for multiple control applications in SDN is proposed in this paper.Furthermore,a price-based joint allocation model of network resource in SDN is built by introducing the price for each of the resources,which can get the proportional fair allocation of link bandwidth and the minimum global delay at the same time.We have also designed a popular flow scheduling policy based on the proportional fair allocation of link bandwidth in order to achieve the minimum global delay.A flow scheduling module has been implemented and evaluated in Floodlight,named virtual forwarding space(VFS).VFS can not only implement the fair allocation of link bandwidth and minimum delay flow scheduling in data plane but also accelerate packet forwarding by looking up control rules in control plane.

Spatial distribution features of sequence types of moderate and strong earthquake in Chinese mainland

Based on 294 earthquake sequences with magnitude greater than or equal to 5.0 occurred in Chinese mainland since 1970, the spatial distribution features of sequence types have been studied. In southwestern China, it takes mainshock-aftershock sequence type （MAT） as the major in Chuan-Dian rhombic block and concerned Xianshuihe-Anninghe-Xiaojiang seismic belt, as well as in Jinshajiang-Honghe seismic belt. Multiple mainshock type （MMT） mainly distributes in western Yunnan, and Longlin and Lancang areas in Tengchong-Baoshan block in west of Nujiang-Lancangjiang fault zone. A few isolated earthquake type （IET） mainly occurred in northwestern Sichuan and there is no IET occurred in Yunnan region. In northwestern China, it takes mainshock-aftershock sequence type （MAT） as the major in west segment of South Tianshan in Xinjiang region. Some MMT also occurred in this area in the intersection of Kalpin block and the Puchang fault zone. It takes IET as the major in middle Tianshan in Xinjiang. Along the Qilianshan seismic belt, most of sequences are MAT. In Qinghai region, it takes MAT as the major, but the regional feature of the spatial distribution of sequence types is not very clear. In North China, it takes MAT as the major in Yinshan-Yanshan-Bohai seismic belt, north edge of North China, and in Hebei plain seismic belt, as well as in sub-plate of lower river area of Yangtze River. In intersection of north segment of Shanxi seismic belt and the NW-trending Yinshan-Yanshan-Bohai seismic belt, there are several moderate or strong MMT with magnitude from 5.0 to 6.0 occurred. In south of North China around the latitude line of 35°N, it takes IET as the major. The spatial distribution of sequence types is relevant to the patterns of tectonic movements. MAT is mostly produced by the ruptures of locked units or asperities or the neonatal separating segments inside the fault zones. MMT is generally relevant to the conjugate structures or intersection of many tectonic settings. Further extension of simple fault often produces IET. Spatial distribution of sequence types is also correlative to the regional and deep environment of crustal medium to some extent. MAT mainly distributes in high velocity area in upper crust or in the transition zone between high velocity area and low velocity area, MMT mostly occurred in the low velocity area in upper crust.

A REVIEW OF THE GEOGRAPHY OF ENTERPRISE

Since 1960 research in the geography of enterprise hasexpanded dramatically. This review gives a critical analysis of the geography of enterprise around five main facets. Firstly, it briefs five approaches adopted by the geography of enterprise. This is followed by an examination of its main development stops. The third section analyses its major research areas. Some new research trends make up the fourth section. Based on the above review many new theoretical and practical problems needed to be solved urgently for the geography of enterprise in China are posed.

Development of a high-productivity grafting robot for Solanaceae

Grafting is a green,environmentally friendly,and sustainable way to prevent soil-borne diseases.Although artificial grafting is the main grafting approach used for grafting production,it has some problems which are low productivity,unstable operating quality and labor-intensive.Hence,some countries have been engaged in the development of grafting robots for the past two decades;however,the productivity of these grafting robots has no advantage when compared to artificial grafting.This study aims to develop a high-productivity grafting robot(HPR)for Solanaceae.To improve grafting productivity,this paper adopted plug trays to feed crown-removed rootstocks automatically and carried out multi-plant simultaneous grafting to improve grafting productivity and extensibility.Manipulators were employed to take out rootstocks,increase the distance between them,and transfer them to transfer cups for the simultaneous multi-plant grafting.At the same time,negative pressure mechanisms were designed for speeding up the auxiliary feeding of root-removed scions.Although the HPR was designed in a two-operator mode,a one-operator mode can also be implemented by adjusting the control program.Tests were conducted by varying the artificial feeding speed to analyze the performance of the grafting robot.The results showed that the productivity of the robot in the two-operator mode was 2250 plants/h,and 1542 plants/h in one-operator mode;comparing the artificial feeding productivity with auto grafting productivity,it was found that the capacity of the grafting robot was higher than the feeding speed of the one-operator mode but lower than that of the two-operator mode.

A method to predict cooling load of large commercial buildings based on weather forecast and internal occupancy

Considering the fact that customers of large commercial buildings have the characteristics of the higher density and randomness, this paper presented an air- conditioning cooling load prediction method based on weather forecast and internal occupancy density. The multiple linear feedback regression model was applied to predict, with precision, the air conditioning cooling load. Case analysis showed that the largest mean relative error of hourly and the daily predicting cooling load maximum were 18.1% and 5.14%, respectively.