Selection of organic Rankine cycle working fluid based on unit-heat-exchange-area net power

To improve energy conversion efficiency, optimization of the working fluids in organic Rankine cycles(ORCs) was explored in the range of low-temperature heat sources. The concept of unit-heat-exchange-area(UHEA) net power, embodying the cost/performance ratio of an ORC system, was proposed as a new indicator to judge the suitability of ORC working fluids on a given condition. The heat exchange area was computed by an improved evaporator model without fixing the minimum temperature difference between working fluid and hot fluid, and the flow pattern transition during heat exchange was also taken into account. The maximum UHEA net powers obtained show that dry organic fluids are more suitable for ORCs than wet organic fluids to recover low-temperature heat. The organic fluid 1-butene is recommended if the inlet temperature of hot fluid is 353.15-363.15 K or443.15-453.15 K, heptane is more suitable at 373.15-423.15 K, and R245 ca is a good option at 483.15-503.15 K.

Working in Remote Areas Services are scarce in mountainous regions

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Factors Influencing Migrant Workers' Urban Labor Patterns: Willing Working Time in Urban Areas as the Mediator

China is witnessing a very complicated economic development environment.Migrant workers'working patterns will directly affect their income level and the realization of many economic and social development goals.This paper collects relevant data from three places:Shanghai,Lanzhou and Chengdu for empirical research whose results show that determinants of migrant worker's willing working time in urban areas mainly include the“income-consumption difference”,“urban-rural consumption difference”and their“urban income and expenditure uncertainty”.These factors directly affect their effective working time in the city,and determine their choice of choosing corresponding work patterns.From the significant differences of these factors,we can see that migrant workers in China is still struggling to solve their material needs under the pressure of livelihood,and less attention is paid to their spiritual needs and the pursuit of quality of life.

Driving factors and the implications of work choices of rural laborers in ecologically vulnerable areas in North China

Using rural survey data for the year 2009,we provide evidence of work choices of rural laborers in ecologically vulnerable areas in North China,and model these choices as a function of characteristics of individuals,households,and land endowments.The findings reveal large differences between males and females,and between non-farm employment and part-time farming engagement Land scarcity is still an important driving factor in non-farming participation of rural laborers in the study area;and in the current case of land productivity and the total amount of land,there are still surplus rural labor forces in the study area.Diversification of livelihood reduces the pressure on land,thus facilitating ecosystem conservation.So,the paper concludes with the argument that establishing coordination mechanisms among non-farm employment of rural laborers,agricultural production,and restoration of ecosystems are essential for mitigating the conflicts of ecological security,agricultural production,and rural development in mis area.

Christian Faith Rush in Rural Areas and Social Work Intervention

To make the public have rational knowledge of the Christian faith rush in rural areas and guide coordinated development of Christianity with the socialist society, we analyzed reasons and complex influence on rural social development from aspects of society and individual and attraction of Christianity by the Literature Analysis Method. In view of its negative effect, we put forward several countermeasures from the perspective of social work intervention, such as improving farmers' overall qualities, promoting effective implementation of social security system, and correcting believers' understanding of Christianity. Finally, we introduced situation of Christian faith in other countries and reference and directive significance to China.

Active protection of work area against explosion of dust-gas mixture

Potentially explosive atmosphere can occur not only in the production systems of the food,energy,chemical and petrochemical industries but also in the production processes of the mining industry.Gases,vapours,mists and dusts arise can escape in an uncontrolled way during production,processing,transportation and storage of flammable substances.In combination with oxygen,they create explosive atmospheres that,if ignited,lead to an explosion causing catastrophic damage to peopled lives and property.To protect against the results of hazardous dust-gas mixtures explosions in a confined work space,where employees can stay,various control and protection mechanisms are used in the form of an active explosion-proof system.The article presents the results of tests on an active system for limiting the effects of ignition of gas and/or dust based on a highly efficient explosion suppression system-equipped with an ignition detection system,high-pressure fire extinguisher and a power supply and trigger system.Smokeless powder was used as the explosive charge and sodium bicarbonate as the suppressive material.Tests of the effectiveness of the active explosion suppression system were carried out on two devices:a small-size dry dust collector and a zone extinguishing system adapted for direct explosion suppression in closed working spaces.In both cases,the explosion suppression process took place through the action of extinguishing powder blown out of the fire extinguisher after membrane perforation by compressed combustion products.

Wireless Regional Area Networks and Cognitive Radio(1)

IEEE has set up in October 2004 the IEEE802.22 Working Group—Wireless Regional Area Network (WRAN) Task Force to work out air interface standard based on Cognitive Radio (CR) technologies. The standard includes Physical Layer (PHY) and Media Access Control (MAC),to use the already allocated fallow spectrums to broadcast TV in a non-interference way. The WRAN employs CR technologies to sense and estimate the television frequencies and use the technologies of dynamic spectrum management to find and then allocate idle spectrums. The CR technologies are representing one of the major trends for future wireless communications. This article on WRANs and CR technologies will be divided into two issues. In this issue,WRANs and IEEE 802.22,CR technologies are introduced. And the second part in the next issue will analyze the applications of CR technologies.

Ground stability of new surface buildings erected on site above worked-out area

The subsided area caused by mining is expanding gradually in coal mining areas. In order to occupy less or no farmland, many mining areas are constructing or intend to erect new buildings (structures) on the ground sites above the worked-out areas. The long-term safety of the new buildings is of great importance. This matter should be, therefore, handled with great care. Following an analysis of the different conditions of the worked-out areas, and the characteristics of the failure of different types of worked-out areas and their overlying strata, the cause for the occurrence of residual deformation of the surface above the worked-out area was explained. The techniques for (evaluating) the stability of ground site for erecting new buildings above worked-out area, and the technical measures for protecting such buildings were proposed. The ground stability evaluation techniques were introduced by reference to specific cases.

Analysis of Air Exchange System Influence on Thermal and Concentration Modes in the Local Working Area under Radiant Heating Conditions

One of the effective options for energy saving in terms of heat costs for the formation of routine thermal conditions of working areas of large-sized industrial premises is the replacement of traditional convective(water)heating systems with systems,the main part of which are gas infrared emitters.But the mass introduction of such systems based on emitters was held back until recently by the lack of scientific and technical foundations for ensuring not only the routine thermal conditions of local working areas,but also ensuring acceptable concentrations of carbon dioxide,which is formed during the operation of a gas emitter.Solving the latter problem by the method of experimental selection of heating and air exchange modes is practically impossible due to the multivariate nature of possible solutions to this problem.Therefore,the purpose of the work is to analyze the results of theoretical studies of the possibility of ensuring an acceptable level of carbon dioxide concentrations in local working areas during the operation of gas infrared emitters and an air exchange system.Numerical modeling of heat and mass transfer processes under such conditions was performed in a fairly wide range of the main significant factors:air flow rate in the air exchange system from 0.01 to 0.04 kg/s,the position of the air inlet and outlet channels relative to the radiator and the local workplace(height from 0.3 to 4.1 m).It was found that by varying the numerical values of these factors,it is possible to ensure carbon dioxide concentrations in the local working area within the permissible limits of up to 1400 ppm.

残膜回收机有效作业面积监测系统设计研究

为便于新疆棉田残膜回收的精准作业收费和补贴,设计了一种残膜回收机有效作业面积监测系统。通过仿真试验对比锁相放大器降噪前后残膜回收机作业时经纬度数据,得出锁相滤波对于噪声环境有较好的抗干扰性能;采用高斯投影正算方法将降噪后经纬度数据转化为平面坐标,得出1.5°带的高斯投影的相对误差相较于3°带降低了0.01%。同时,利用卡尔曼滤波算法和构成角方法筛选有效作业轨迹,使用缓冲区法计算重复作业面积,最终利用轨迹算法精准获取残膜回收机有效作业面积,得出所设计的残膜回收机有效作业面积监测系统对于大块农田测量时相对误差为2.6%,对于小块农田测量时相对误差为3.3%。研究结果表明:所设计的残膜回收机有效作业面积监测系统可以精确计算出残膜回收机的有效作业面积,为残膜回收机作业质量评估提供了一定的理论基础。

认知功能损伤对双任务站立影响的中枢机制:功能性近红外脑成像系统分析

背景:轻度认知障碍老年人由于认知功能下降,姿势控制能力下降,易发生跌倒。双任务范式由于更贴近日常生活,常被用于评估姿势控制能力,但以往对于轻度认知障碍老年人的认知与姿势控制双任务研究主要探讨姿势控制的外在表现特征,中枢神经机制的直接证据依然缺乏。目的:探讨轻度认知障碍老年人在执行站立姿势控制-空间工作记忆双任务时大脑躯体感觉运动皮质激活特征。方法:采用蒙特利尔认知量表(MoCA-B)筛选受试者,共纳入轻度认知障碍老年人16人、认知功能正常老年人17人,进行5种任务测试,分别为空间工作记忆(SIT)、双足平衡站立(SD)、Romberg站立(SR)、双足平衡站立-空间工作记忆双任务(DD)、Romberg站立-空间工作记忆双任务(DR);同时使用功能性近红外脑成像系统和三维测力台收集躯体感觉运动皮质(20个通道)的血液动力学、足底压力中心(COP)摆动轨迹数据。结果与结论:①在Romberg站立、双足平衡站立-空间工作记忆双任务、Romberg站立-空间工作记忆双任务下,轻度认知障碍老年人前后、内外方向足底压力中心位移均显著大于认知功能正常老年人(P<0.05);②在双足平衡站立-空间工作记忆双任务下,轻度认知障碍老年人15通道(右侧前运动皮质/辅助运动区)的氧合血红蛋白变化量值显著大于认知功能正常老年人(P<0.05);在Romberg站立-空间工作记忆双任务下,轻度认知障碍老年人15,17通道(右侧前运动皮质/辅助运动区)的氧合血红蛋白变化量值均显著大于认知功能正常老年人(P<0.05);③在Romberg站立-空间工作记忆双任务下,轻度认知障碍老年人内外方向足底压力中心位移与15通道的氧合血红蛋白变化量存在显著正相关(r=0.659,P<0.05),认知功能正常老年人内外方向足底压力中心位移与15通道的氧合血红蛋白变化量存在高度正相关(r=0.840,P<0.05)。结果表明,与认知功能正常老年人相比,轻度认知障碍老年人在站立姿势控制-空间工作记忆双任务中站立姿势控制能力较弱,右侧前运动皮质与辅助运动区激活水平更高,更多的脑资源用于侧向姿势控制,可能是轻度认知障碍老年人认知衰退导致站立姿势控制能力变弱的大脑补偿机制。

强震区隧道洞口段新型墙-板抗减震措施的效果分析

为了进一步提高强震区铁路隧道的安全以及抗震性能,依托包银铁路甘德尔山隧道,运用数值模拟软件FLAC 3D,针对强震区隧道洞口段墙-板和墙-板-减震层的抗减震作用效果进行研究。研究结果表明,与不采用抗减震措施相比较,采取墙-板抗震措施后,横向位移减小了5.95%,竖向位移减小了45.87%,最小安全系数增大了40.91%~49.25%,最大主应力的抗震作用效果达到了63.56%,最小主应力的抗震作用效果为4.04%,最大剪应力抗震作用效果为8.35%;采取墙-板-减震层减震措施后,横向位移减小了13.11%,竖向位移减小了43.88%,最小安全系数增大了65.82%~74.50%,最大主应力的减震作用效果达到了75.11%,最小主应力的减震作用效果为10.21%,最大剪应力减震作用效果为12.80%。采用墙-板-减震层的抗减震措施优于墙-板结构。推荐采用墙-板-减震层措施对甘德尔山隧道进行抗减震加固设计。

Assessment of the Protected Areas Strategy in Togo under Sustainable Management: The Case Study of Oti-Keran, Togodo, and Abdoulaye Faunal Reserve

This study aims to identify the drivers of environmental degradation due to the dependency of surrounding residents on three protected areas in Togo, Africa (Oti-Keran, Togodo, and Abdoulaye national parks (abbr. OTA national parks)). Surveys of villagers conducted in and around the OTA national parks added to data downloaded from Indexmundi data portal. National-level trend analysis results indicated: 1) the number of terrestrial protected areas showed an upward trend, while savannah and forest cover showed alarming decrease trends. 2) At the local level, supplying socio-economic needs in the three selected protected areas directly resulted in biodiversity degradation through animal grazing, hunting and farming. 3) Over 70% of the respondent’s livelihoods consisted of farming and related dependencies on the protected areas for timber and non-timber forest products and income despite the protected status hold by these classified areas. 4) The OTA national parks have been experiencing an increase of anthropogenic pressure such as uncontrolled tree logging and hunting, which seriously impacts animal and vegetation biodiversity. 5) Policymakers should invest more resources in implementing an integrated management system based not only on a holistic vision of the PA that includes participatory management but also accounts for multi-dimensional principles to enable anthropogenic activities in and around the protected areas to satisfy sustainable development requirements.

Yangtze River Delta,The Works of Nature

The Yangtze River Delta or Yangtze Delta.also called Chang Jiang Delta,or the Golden Triangle of the Yangtze,genelallv comprises the triangular-shaped territory of Wu-speaking Shanghai,southern Jiangsu province and northern Zhejiang province of China.The area lies at the heart of the region traditionally called Jiangnan.The Yangtze River drains into the East China Sea.

软土地区基坑前排倾斜双排桩支护现场试验及工作机理

基坑倾斜桩支护大幅提高了无支撑支护结构的适用深度,具有造价低、施工便捷、绿色低碳、变形控制好等特点,然而目前研究多集中在单排倾斜桩,对前排倾斜双排桩支护的试验、理论与应用的研究均较少。针对前排倾斜双排桩支护基坑开展了现场试验,同时采用有限元方法分别从前排斜桩、桩顶连梁及桩间土体作用3个方面深入探究了前排倾斜双排桩支护的工作机理,进一步分析了直斜桩长度和排距对前排倾斜双排桩支护结构受力变形性能的影响。结果表明,相比传统竖直双排桩,前排倾斜双排桩支护结构的支护性能显著提升,前排斜桩主要发挥“斜撑”作用,连梁主要起到将直斜桩及冠梁连接成一个空间刚架的作用,桩间土体能够提高桩土摩阻力,进而有效减小前排倾斜双排桩变形。研究成果有助于前排倾斜双排桩的推广和应用。

Public Space Demand and Adaptive Behavior of Residents in Old Residential Area of Ancient City: Based on Qingyi Garden of Beirenyi Hutong in Kaifeng

The majority of the literature on the transformation of cultural promotion space in old residential areas in the United States and abroad is written from the top-down perspective of God,such as architects,planners,developers,and even government officials,and only a few of them examine the designer’s work from the perspective of aborigines.To sample life and gain insight into human nature,find another means to be as near to the public as possible,listen to the voice of users,and conduct an in-depth examination of the freestyle works altered by the old residential districts through the“people’s architectural planner.”

2024年中央一号文件的突出亮点

2024年中央一号文件以习近平新时代中国特色社会主义思想为指导,为2024年乃至今后一段时期的“三农”工作进行了系统部署和具体安排,呈现了一系列突出亮点。即:凸显了贯彻中央经济工作会议精神和深化对“三农”工作的规律性认识,明确了学习运用“千万工程”经验引领乡村全面振兴的要求,重视运用战略思维和改革创新,统筹强化软政策引领与硬政策支撑作用,坚持守正创新,确保国家粮食安全有新招,确保不发生规模性返贫底线更明确措施更有力,强调以坚持“三个提升”为重点建设宜居宜业和美乡村。

由强省到强国:省级政府推进特色农业强国政策体系的异质性研究

农业强省是农业强国的有机组成部分,地方政府对农业强国战略的推进是农业强国建设的重要环节。农业强国的政策体系主要以政策背景、政策手段和政策目标三大要素来构成。其中,政策背景作为出发点,分别从制度空间、经济空间、社会空间描绘出现实图景。各省以构建保障体系、产业体系、支持体系和创新体系的政策手段来贯彻落实农业强国战略,勾勒出鲜明的农业强国建设着力点。政策目标是政策体系的归宿点,央地政策的精准匹配体现出协同治理的思想。在建设农业强国的实践中,各省级政府要统筹发挥好不同体系的作用,打造具有弹性的特色农业强国建设体系,协调好中央与地方治理的关系,实现央地协同发展。

乡村振兴背景下社会工作参与农村社区治理的路径探究

乡村振兴的实现是中国现代化进程中的关键环节。农村社区的治理不只是社会治理结构中最基础的部分,同时也是构成国家治理体系和治理能力现代化的关键支柱。党的十八大以来,党中央对我国农村社区治理问题高度重视,提出许多新观点和新思路。社会工作在推动农村社区治理、促进乡村振兴的过程中起着不可替代的作用。该文探讨在乡村振兴的背景下,社会工作参与农村社区治理的可行性、困境、提升策略等问题,期望进一步增强农村社区的治理能力,确保农村社区治理的高效性,并最终达到农村社区的良好治理目标。

民族地区地方性医学院校研究生导师指导研究生开展科研工作调查分析——以右江民族医学院为例

目的:分析民族地区地方性医学院研究生导师指导研究生的科研工作情况,为研究生导师队伍管理提供参考依据。方法:参考相关文献和学校研究生培养相关管理规章制度制定调查问卷,对76名硕士研究生导师进行问卷调查。结果:在指导研究生开展科研工作中,98.68%的导师选择与研究生面谈的交流方式;89.47%的导师选择让学生参与自己的课题研究;81.58%的导师每年投入的累计时间大于3个月;77.63%的导师每学期与研究生见面次数在6次及以上;89.48%的导师跟研究生见面时交流时间大于0.5小时;38.16%的导师对研究生投入的科研经费2.0万元以上。97.37%的导师认为研究生参与科研工作积极性高;90.79%的导师认为研究生有学术责任感;76.32%的导师认为研究生思考问题不全面,69.74%的导师认为研究生的基础知识不牢固。结论:该校应加强管理,确保导师在研究生科研素质培养中的时间、经费等的投入,同时导师应要求学生重视科研思维的培养和基础知识的学习。