氮肥对挖沙废弃地能源草生长特性与生物质产量的影响

能源草是目前最具发展潜力的生物质资源之一,为获得能源草在华北地区边际土地种植过程中肥料效应方面的基础数据,在京郊挖沙废弃地上开展了能源草柳枝稷(Panicum virgatum L.)、荻(Triarrhena sacchariflora(Maxim.) Nakai)和芦竹(Arundo donax L.)的氮肥效应试验。结果表明:氮肥对边际土地上种植的3种能源草的株高、分蘖数量、叶片SPAD值和生物质产量均具有显著的促进作用(P<0.05);生物质产量与土壤氮素浓度之间的回归分析表明,在挖沙废弃地上获得柳枝稷、荻和芦竹最高生物质产量的适宜土壤氮素浓度分别为115.1mg·kg^-1、131.0mg·kg^-1、125.1mg·kg^-1。     

Power Output Improvement of PV Module for Agricultural Use by Using Inexpensive Sunlight Concentrator

PV modules are used as stand alone power sources for agricultural equipments such as lifting pumps in farms, where the power infrastructure is not yet improved. In order to expand the agricultural use of PV module, the cost of PV generation should be reduced. In this paper, the power output performance of a commercial PV module was improved by using a sunlight concentrator that could be assembled inexpensively and a simple sun-tracking method.     

Logistic模型法和恢复费用法估算城市生活污水的价值损失

分别采用Logistic模型法和恢复费用法估算了2001～2008年滨州市生活污水由于COD的污染而造成的价值损失,发现2种方法的估算结果差别较大,年平均损失分别为5287.78万和2663.10万元,前者比后者多了近1倍,认为Logistic模型法的估算结果更加接近实际;2种方法估算的2001～2008年滨州市生活污水价值损失总体变化趋势一致,其中2002年最高,之后开始降低,2006年达到最低,之后又升高。     

天津设施西红柿成本及效益分析

对天津市设施西红柿的历史变化及成本构成进行了研究,结果表明,天津市设施西红柿成本自1991年以来有较大幅度增长;在成本构成中,劳动力工价、农膜、化肥、农家肥对总成本影响大;对成本收益的比较分析表明,西红柿收益处于4种设施蔬菜中游水平。     

基于道路网络影响的物流运输成本研究

物流一直被认为是企业利润的重要来源.随着我国城市化进程的加快,道路网络相应地发生了变化,物流运输成本也随之而变.文章重点分析了道路等级和路网结构对物流运输成本的影响,以优化物流企业的运输路径,增加其经济利润.     

关于设计人员做好电力工程造价管理的几点经验总结

我国电力工程项目仍普遍存在严重的概算超估算、预算超概算、决算超预算的“三超”造价失控现象,严重影响了国家电力建设工程的经济效益,文章从如何控制工程造价,优化电力工程设计方案进行相关总结探讨.     

黄河三角洲可吸入颗粒物造成的居民健康经济损失估算

采用泊松回归比例危险模型,选用国内外meta分析结果的污染物暴露-反应关系系数,参考相关健康效应终点的统计资料,估算了黄河三角洲地区归因于可吸入颗粒物的居民健康经济损失。结果表明,2010年可吸入颗粒物（PM10,参考浓度取40μg /m3）造成的人群急性健康经济损失为16313.69万元,超额死亡经济损失为3347.42万元,合计19661.11万元,占该地区当年GDP的0.036%,对该地区居民健康造成的影响不容忽视。     

“80后”农民工教育培训成本补偿机制研究

为了解决“80后”农民工教育培训经费不足的困境,并研究其教育培训成本补偿不足的问题。结合“80后”农民工教育收益率,着重分析其教育培训成本分担主体构成以及成本补偿的原则,从四方面构建“80后”农民工教育培训成本补偿机制,为相关部门的农民工教育培训投资决策提供一定参考价值。     

Production and application of on‐grown Artemia in freshwater ornamental fish farm

Abstract

This paper describes a pilot culture system for the production of on‐grown Artemia in freshwater ornamental fish farms. The system had 21 culture units, each consisting essentially of three components: an oval‐shaped raceway, an air‐water lift system and two waste collectors. Using artificial seawater at 20 ppt for culture and at a mean production rate of 3 kg/m³ of water in a 12‐day cycle, the system had a production capacity of 8 metric tons of on‐grown Artemia a year. Biochemical analyses were preformed to evaluate the nutritional value of the on‐grown Artemia against three conventional live feeds, viz. live Artemia nauplii, live Moina and frozen bloodworms. Cost‐benefit analysis showed that with a capital investment of US$ 82,000 and an annual cost of production of US$ 81,000, the system achieved a high internal rate of return of 88% over a 10‐year period and a short payback period of 1.23 years. The availability of on‐grown Artemia would not only offer farmers and exporters a better alternative live food organism for feeding to their fish, but more importantly the possibility of enhancing the fish performance and quality through bioencapsulation.     

ASSESSING HAWAII'S AQUACULTURE FARM AND INDUSTRY PERFORMANCE

This investigation uses farm-level data from the U.S. Census of Agriculture to evaluate the economic performance of the aquaculture industry in Hawaii. We first examine the entire aquaculture industry by assessing its profitability, efficiency, and input cost structure over time and across economic farm sizes; we then proceed to analyze the farms at the individual subsector levels of crustacean, Chinese catfish, other foodfish, and ornamental farms. The results reveal a wide variation in performance across farms, even within the same subsectors. In 2007, 57.6% of the aquafarms generated a profit; however 39.4% of the farms were found unable to cover their variable cash expenses. The presence of significant economies of scales were detected in performance with full-time operations being found more profitable and efficient than part-time operations. Finally, Hawaii's labor cost share for aquaculture enterprises is about 3.5 times greater than that found on the continental United States.