农村户用分体式地源热泵系统运行特性分析及应用——以邯郸地区某示范项目为例

为了解决京津冀地区农村冬季采暖存在的环境污染问题,以邯郸地区示范项目典型农宅为例,提出了一种新型的分体式地源热泵系统。首先,利用TRNSYS软件建立分体式地源热泵系统模型,模拟分析了系统的长期运行特性;再通过费用年值法和污染物排放量计算,对比分析该地区常见的4种采暖方式的经济性和环境效益;最后选出最合理的运行系统。结果表明：1）分体式地源热泵系统运行高效且稳定,运行期间系统COP达3.5以上,热泵机组COP达4.0以上;2）在间歇运行方式下,土壤平均温度一年的降幅为0.8%,十年的降幅为3.6%;3）在4种采暖方式综合对比下,分体式地源热泵系统运行费用较低且环保性较好。分体式地源热泵系统的运行性能研究为户用分体式地源热泵系统在京津冀地区典型农宅的应用推广提供了参考借鉴。     

阶梯可调毛细管组件的应用研究

为实现设备出厂后毛细管组件可以根据现场工况阶梯调节,保证每台空调器工作性能达到最优,开发一种新型阶梯可调毛细管组件。对毛细管组进行了优化组合,确定了毛细管组件的尺寸。实验测得基于阶梯可调毛细管组件的2匹小型地源热泵在不同工况下的制热量与COP,较同型号的单一毛细管机组的制热量和COP最高可提高15%。     

一种清洁能源与市政热网互补的供热系统设计及模拟研究

北方地区的建筑供暖需求随着城市建筑面积的迅速增长而不断增加,而城市热网改扩建缓慢,供热能力不足,距城区较远的新建及改扩建小区的供暖需求面临挑战,并且供暖带来的高能耗及环境污染问题日益严峻。针对此类问题,提出了将太阳能、空气能与传统市政热网相结合、互为补充的清洁能源与市政热网多能互补的集中供热系统,利用TRNSYS软件建立系统模型,设计系统5种不同的运行模式及相应的运行控制策略,并以石家庄市某新建小区为例进行分析。模拟运行结果表明,在整个供暖季中,运行时间较长的是太阳能辅助双热源(水源)热泵供热模式和双热源(空气源)热泵供热模式,清洁能源的供热比例为82.15%,热泵机组效率高,平均COP为4.06,远高于常规的热泵机组。研究结果可为周边供热能力不足的新建及改扩建小区选择供热系统提供参考。     

过冷器前节流中间补气空气源热泵性能模拟研究

为了解决空气源热泵在低温工况下性能衰减、排气温度过高和制热不足等问题,以过冷器前节流中间补气空气源热泵循环系统为研究对象,建立了以带补气单螺杆压缩机为热力系的循环理论数学模型,给出了中间平衡补气压力的计算流程,并对系统参数进行了模拟计算。结果表明：与不补气压缩系统相比,补气对系统COP、制热量的提升具有明显作用;压缩机的补气口越靠近吸气结束位置,系统性能参数越好;在蒸发温度-25 ℃情况下,补气与过冷器过冷侧液体出口的温差降低6 ℃,压力损失系数从0.42增加到0.82,COP提升了14%左右。因此,在能够保证过冷器正常运行的情况下,尽可能减小补气口与过冷器过冷侧液体出口的温差,尽量减少补气过程中的压力损失,有利于补气热泵系统性能的提升。研究结果可为过冷器空气源热泵系统的设计提供理论支持。     

河北保定高速某服务区蓄联热泵清洁供暖技术改造研究[JP]

为了提升空气源热泵低温环境中的热效率,解决热泵冬季易结霜、故障率高等问题,提出一种利用相变蓄能装置将空气源热泵和水源热泵组合的蓄联热泵技术。以河北保定高速某服务区蓄联热泵的改造工程为例,设计了蓄联热泵系统改造方案,并将蓄联热泵联合供暖系统的实际运行数据与位于同一地区、相似建筑中使用单一热源供暖的空气源热泵系统运行数据进行对比,考察供水温度、室内温度、单位供暖面积的耗电量和COP值等因素的变化情况。研究结果表明,在相同室外气温、相同单位面积供暖热负荷的条件下,蓄联热泵供暖效果更稳定,室内温度更高,蓄联热泵每平方米耗能相比空气源热泵低15.5%,综合COP提高了20.68%,静态投资回收期为11.89年。蓄联热泵清洁供暖技术具有一定的可靠性和经济性,适用于低温持续时间较长的偏远山区等寒冷地区,研究结果对蓄联热泵的推广具有重要的借鉴意义与应用价值。     

模块组合式燃气热水锅炉在采暖中的应用

概述北京市东城区政府办公楼总建筑采暖面积 2 60 0 0m2 ,2 0 0 1年以前冬季采暖一直使用燃煤锅炉 ,随着市区内天然气的普及和北京市出台的四环以内取消燃煤锅炉政策的实施 ,2 0 0 1年 10月东城区政府取消了原燃煤锅炉 ,使用 4台美国尤提卡JC -3 0 0 0模块式燃气热水锅炉 ,经过一个采暖期 12 0天的使用表明 :该锅炉操作简便 ,安全可靠 ,随热负荷变化调整供热量快捷、灵活 ,燃烧性能稳定 ,平均热效率高 ,与目前使用的其它类燃气锅炉相比 ,节能效果明显 ,取得了良好的经济效益和社会效益。采暖系统中安装 4台模块式燃气锅炉 ,共投资 80余万元…     

太阳能-生物质能-谷电蓄热联合供暖系统研究

为了提高多种新能源组合供暖的热效率,考察太阳能-生物质能-谷电蓄热联合供暖系统的供暖效果,利用TRNSYS软件中的TRNbuild模块对实验室进行供暖期内逐时热负荷仿真计算,以动态负荷为基础搭建太阳能与生物质锅炉联合供暖系统的TRNSYS 模型,并对仿真结果进行了实验验证。研究结果表明：7种运行模式及控制策略联合互补,实现了各单元在供暖过程中不同时段的协调控制,保证了联合供暖系统的稳定运行;联合供暖系统供水温度从40 ℃升高至60 ℃,其供热效率降低了11.08%,太阳能保证率降低了23.35%;集热器面积从20 m²增大到40 m²时,太阳能保证率增加25.99%,供热效率降低了2.11%;集热水箱容积从1.5 m³增大到4 m³时,太阳能保证率增加8.67%,供热效率增加了4.31%;系统平均供热效率实验值与模拟值误差为4.29%,平均供热指标实验值与模拟值误差为6.15%;联合供暖系统测试日平均温度为19.76 ℃,能够达到寒冷地区冬季供暖室内温度18~24 ℃的采暖要求。联合供暖系统具有良好的热舒适性,研究结果可为北方地区多源互补供热系统工程优化设计提供依据。     

基于MATLAB改进的相变蓄热集热器在太阳能制冷系统中的性能分析

为提高太阳能制冷系统的性能参数,建立了集热蓄热一体化集热器模型,以进行应用计算。基于TRNSYS与MATLAB软件联合模拟运行的无辅助热源的太阳能吸收式制冷系统,分别对采用传统集热器的系统和采用改进后的相变蓄热集热器的系统的各部分参数的变化进行分析,对集热器的效率、系统制冷量和性能系数进行了对比。模拟结果表明,在太阳能吸收式制冷系统中,采用改进后的相变蓄热集热器,与传统的集热器相比,其集热效率提高约7.62%,系统制冷量增加约9.99%,系统的COP增加约23.60%。本模型能较好地应用于太阳能吸收式制冷系统的模拟。     

零碳建筑技术路线研究——以保定市某幼儿园为例

为实现零碳建筑的零碳排放和超低能耗目标,提出了零碳建筑的技术路线。利用负荷能耗指标作为技术评价标准,以保定市某幼儿园实际工程为例,通过DeST软件模拟,分析了本项目全年负荷变化,冷热负荷指标以及负荷能耗指标,然后通过正交试验与极差分析得出不同影响因素对建筑热负荷的影响程度。结果表明,零碳幼儿园全年累计热负荷指标为61.60 kW·h/m~2,全年累计冷负荷指标为75.99 kW·h/m~2,采暖季热负荷指标为18.36 W/m~2,空调季冷负荷指标为25.76 W/m~2;不同影响因素对建筑热负荷的影响程度从大到小依次为外墙传热系数人员密度设备功率屋顶传热系数,对建筑冷负荷影响程度从大到小依次为人员密度设备功率外墙传热系数屋顶传热系数。零碳建筑技术路线的运用对于降低建筑能耗、实现建筑零碳目标具有重要意义。     

零碳建筑技术路线研究

为实现零碳建筑的零碳排放和超低能耗目标,提出了零碳建筑的技术路线。利用负荷能耗指标作为技术评价标准,以保定市某幼儿园实际工程为例,通过DeST软件模拟,分析了本项目全年负荷变化,冷热负荷指标以及负荷能耗指标,然后通过正交试验与极差分析得出不同影响因素对建筑热负荷的影响程度。结果表明,零碳幼儿园全年累计热负荷指标为61.60 kW·h/m~2,全年累计冷负荷指标为75.99 kW·h/m~2,采暖季热负荷指标为18.36 W/m~2,空调季冷负荷指标为25.76 W/m~2;不同影响因素对建筑热负荷的影响程度从大到小依次为外墙传热系数>人员密度>设备功率>屋顶传热系数,对建筑冷负荷影响程度从大到小依次为人员密度>设备功率>外墙传热系数>屋顶传热系数。零碳建筑技术路线的运用对于降低建筑能耗、实现建筑零碳目标具有重要意义。     

Comparing FTTH access networks based on P2P and PMP fibre topologies

There is an ongoing discussion in the market which Next Generation Access (NGA) architecture best suits future needs and which investment and cost differences exist. The discussion can be subsumed as P2P vs. GPON, which is somewhat misleading as this article reveals. The discussion is driven by the fact that the high capital cost and the long asset life time of fibre mean that the technology choices made today will dominate the opportunities for telecommunication business of all market players, incumbents, competitors, content providers and business and residential users for many years in the future.The paper analyzes the cost and other differences between Fibre-to-the-Home (FTTH) access network architectures and their related different wholesale approaches by using the well-known and understood steady state approach applied in other NGA analyses in the past. In addition to the steady state analysis a dynamic cost evaluation is included taking into account the different investment behaviour of the FTTH architectures over time. The results describe investment and cost differences between architectures, incumbents and wholesale based competitive operators. The analysis has been performed for different geotypes (clusters) of decreasing population density in a representative European settlement structure.     

Indigenous peoples’ nutrition transition in a right to food perspective

In indigenous communities the nutrition transition characterized by a rapid westernization of diet and lifestyle is associated with rising prevalence of chronic disease. Field work and literature reviews from two different policy environments, Argentina (Jujuy) and Canada (Nunavut), identified factors that add to indigenous peoples’ disease risk. The analytical framework was the emerging human right to adequate food approach to policies and programmes. Indigenous peoples’ chronic disease risk tends to increase as a result of government policies that infringe on indigenous peoples’ livelihoods and territories, undermining their economic system, values and solidarity networks. Policies intended to increase food security, including food aid, may also fuel the nutrition transition. There is a need to explore further the connection between well-intended policies towards indigenous peoples and the development of chronic diseases, and to broaden the understanding of the role that different forms of discrimination play in the westernization of their lifestyles, values and food habits. Food policies that take due account of indigenous peoples’ human rights, including their right to enjoy their culture, may counteract the growth of chronic disease in these communities.     

A strategic skill based model of supplier integration and its effect on supply management performance

Supplier integration is a tool to help organizations gain competitive advantage. Strategic supply management skills and the supply management function's perceived status are hypothesized as antecedents to supplier integration leading to supply management performance. The sample for this study includes 152 executive level supply management professionals. The empirical results suggest that strategic skills and perceived status are essential antecedents to supplier integration and subsequent performance. Further, the relationship between strategic skills and performance is mediated by supplier integration. Results of a dominance analysis also suggest which strategic skills are most likely to explain status integration, and performance. These findings have significant implications for supply management theory and practice.     

Cost allocation of WCDMA and wholesale pricing for mVoIP and data services

This study estimates cost-based prices for wholesale voice and data services provided to 3G (WCDMA) MVNOs according to their distinct types. For estimation, 3G MVNOs are classified into different types, and the overall cost of WCDMA facilities are separated into voice and data components based on their subscriber rates, actual traffic rates, as well as efficiency consideration of traffic rates. The study then calculates cost-based wholesale prices of voice and data services for each of the 3G MVNO types. The result of this study shows that a cost-plus pricing scheme can help achieve the policy goals of the regulator, namely, lowering telecommunications tariffs and facilitating the introduction of new convergent-type services, far more effectively than the current retail-minus pricing scheme. The findings of this study may assist firms in developing business models based on 3G networks and telecom regulators in designing policies related to interconnection, mVoIP, prepaid calls, wholesale services, and network neutrality.     

Collectivism,individualism, and outgroup cooperation in a segmented China

A consistent theme in cross-cultural management research is that collectivists are more cooperative than individualists. We use Hofstede's measure for individualism–collectivism and combine it with an experimental measure of cooperation to test this relationship in China. In contrast to the established paradigm, we find that groups with higher individualistic scores are more cooperative than those groups with higher collectivistic scores. We attribute these results to groups being composed of outgroup members. In addition, we find that subjects from the more developed coastal area are more individualistic and cooperative than are subjects from inland China.

电子产品的电磁兼容性设计

首先介绍电磁兼容性的基本概念与研究领域,然后重点阐述电子产品的电磁兼容性设计与测量。     

SPYRO在烯烃原料生产方案测算中的应用

文章对SPYRO裂解模拟软件在石化企业烯烃生产原料优化方案测算中的应用进行了比较深度的概括分析.结合该软件在上海石化的实际应用,认为在劣质化原油加工份额不断增加的趋势下,SPYRO裂解模拟软件有助于石化企业在烯烃生产原料优化选择、生产计划合理安排、原油加工生产效益比较等方面为企业相关决策者提供有效地帮助.     

施工企业工程项目部的建设浅论

工程项目的一次性决定了工程项目部的一次性，而工程项目成本中心与企业利润中心地位又辱致工程项目部的临时性，在工程项目实践过程中，项目经理部的一次性在实现其功能的过程中可能会产生很多局限和负面影响，故项目部应具有相对的稳定性，在此基础上，本对工程项目部建设实践进行了初步总结并提出了建议。     

European consumer preferences for beef with nutrition and health claims: A multi-country investigation using discrete choice experiments

The European Union (EU) nutrition labelling policy aims to facilitate consumers’ food choice, stimulate innovation and facilitate the circulation of foods bearing claims across countries. However, the beef industry has not fully taken advantage of utilizing nutrition and health claims based on the EU nutrition labelling policy to differentiate beef products in the market. This study investigates consumer preferences for nutrition and health claims on lean beef steak. Two choice experiments were conducted among 2400 beef consumers in four EU countries (Belgium, France, the Netherlands, United and United Kingdom). Multinomial logit and error component models were estimated. Our results generally suggest that consumer valuation of nutritional and health claims varies across countries. In Belgium, the Netherlands and France, nutrition and health claims on saturated fat yielded higher utilities than claims on protein and/or iron, while the opposite was found among consumers in the UK. The results imply that marketing opportunities related to nutrition and health claims on beef are promising, but that different nutritional marketing strategies are necessary within different countries.     

Social media as a useful tool in food risk and benefit communication? A strategic orientation approach

Although considerable progress has been made in understanding the determinants of risk perception and in identifying the necessary components of effective food risk and benefit communication, this has not been matched with the development of efficient and appropriate communication tools. Little work has been done examining the implications of the explosion of new media and web technologies, which may offer potential for improving food risk and benefit communication. First, this study examines the views of stakeholders (n = 38) and experts (n = 33) in the food domain on the potential use of these emerging media for food risk/benefit communication. Based on in-depth interviews in six European countries (Belgium, Ireland, Italy, Latvia, Spain and The Netherlands), strengths, weaknesses, opportunities and threats (SWOT) of social media in food risk and benefit communication were identified. Second, a Strategic Orientation Round (SOR) was used to evaluate the relative importance of the SWOT components according to stakeholders (n = 10) and experts (n = 13). Results show that both stakeholders and experts confirm a future role of social media in food risk and benefit communication. Strengths as speed, accessibility and interaction make social media an interesting tool in crisis communication or issue awareness raising. Weaknesses as the lack of a filter, low trust, the risk of information overload and a communication preference for traditional media are acknowledged.