Assessment of Rainwater Harvesting Reticulation Systems to Reduce High Management Costs in Household Buildings

Rainwater harvesting?provides an important alternative source of water in household buildings which?increases water security in urban areas. However, high energy cost consumption by the rainwater harvesting systems results in higher management costs which may derail the investment viability of these systems in households. This prompted this study to establish ways through which the management cost of rainwater harvesting systems can be minimized in household buildings. A survey of 200 households from Greenspan, Komarock, Utawala, Kileleshwa and Runda in Nairobi?County was undertaken as?well?as?data?on?the?type?of?rainwater harvesting?systems, their operation and maintenance cost collected using observation checklists and questionnaires. The findings indicated that rainwater harvesting typologies 1, 2, 4 and 5 had their water pumped from first-level storage to the second-level storage then supplied to usage points by gravity. Whereas, typologies 3 and 6 had their water moved manually and by gravity respectively. On annual operation cost, 100% of households with typology 3 and 6 spent no money whereas, 100%, 75% and 70.6% with typology 4 and 5, 1 and 2 respectively spent Ksh. 1?-?5000. On annual maintenance cost, 100%, 93.7% and 77.8% of households with typology 5 and 6, 3 and 4 respectively spent Ksh. 1?-?5000 while 25% and 22.2% of households with typology 1 and 2 respectively spent Ksh. 5000?-?10,000. Advanced typology 6 with one-level storage point supplies rainwater to all parts of the household by gravity. This eliminates operation costs spent on energy consumption due to pumping of water,?thus minimizing overall management cost spent on rainwater harvesting systems in household buildings.

Ensuring water security by utilizing roof-harvested rainwater and lake water treated with a low-cost integrated adsorption-filtration system

Drinking water is supplied through a centralized water supply system and may not be accessed by communities in rural areas of Malaysia.This study investigated the performance of a low-cost, self-prepared combined activated carbon and sand filtration(CACSF) system for roofharvested rainwater and lake water for potable use. Activated carbon was self-prepared using locally sourced coconut shell and was activated using commonly available salt rather than a high-tech procedure that requires a chemical reagent. The filtration chamber was comprised of local,readily available sand. The experiments were conducted with varying antecedent dry intervals(ADIs) of up to 15 d and lake water with varying initial chemical oxygen demand(COD) concentration. The CACSF system managed to produce effluents complying with the drinking water standards for the parameters p H, dissolved oxygen(DO), biochemical oxygen demand(BOD5), COD, total suspended solids(TSS), and ammonia nitrogen(NH_3-N). The CACSF system successfully decreased the population of Escherichia coli(E. coli) in the influents to less than 30 CFU/m L. Samples with a higher population of E. coli(that is, greater than 30 CFU/m L) did not show 100% removal. The system also showed high potential as an alternative for treated drinking water for roof-harvested rainwater and class II lake water.

红枣两种不同采收方式生产效率及成本比较研究

【目的】红枣作为特色林果业,在全国很多地域都有栽植,但随着人工成本的大幅提高,使红枣种植收益变少,为此,通过对不同采收方式生产效率及成本的比较研究,找到了一种解决成本低、采收率高的方法。【方法】红枣采摘方式采取单因素试验设计,以红枣捡拾机采收为处理,以“吹风机+人工”采收方式为对照,分别调查其采收效率、采收成本。【结果】“吹风机+人工”采收方式采收率为1000 kg/d,红枣捡拾机采收效率更高,为5120 kg/d;每亩(667 m^(2))采收成本“吹风机+人工”采收为397.5元,红枣捡拾机为238.43元,红枣捡拾机采收成本更低,比“吹风机+人工”采收成本降低40%。【结论】红枣捡拾机采收效率更高,生产成本更低。但目前采收机械专利很少有在生产中能普及使用的,需要将损伤率降低到最小的情况下,找到高效实用的方法来加快红枣采收。

广西地区甘蔗机械化收割现状及分析

人工成本是甘蔗产业的主要成本来源之一,而收获环节的人工成本又占了总人工成本的绝大部分。机械化作业可以大大提高甘蔗收获的效率,大幅降低人工成本,因此机械化收获率的高低往往决定了产业成本的高低。广西甘蔗种植面积占全国甘蔗种植总面积的60%以上,全国排名第一,遥遥领先于其余各省。可以说,广西甘蔗机械化收割水平在一定程度上代表了我国的甘蔗机械化收割的总体水平。然而2020/2021榨季,广西地区甘蔗机械化收获率却远低于其他主要的甘蔗种植国家,这使得我国蔗糖产业的竞争力远低于其他主要的蔗糖生产国家。文章从耕地资源、规模特征、气候条件、机械化收获技术、收获设备、产业链内部矛盾等多个角度对广西甘蔗机械化收获率低的原因进行了一定的分析,并针对性地提出了一些解决的方案与措施,以期为提高广西地区甘蔗机械化收割率、降低成本、增强蔗糖产业的国际竞争力提供参考。

带茎采烤对上部烟叶产质量及采烤成本的影响

本研究将上部烟叶带茎采收烘烤(T_(1))与上部烟叶一次性摘叶编杆烘烤(T_(2))、常规采烤(CK)3种方式下烟叶产质量及采烤成本进行对比分析。结果表明:T_(1)处理烟叶各化学指标均处于适宜范围,其烤后烟叶总植物碱显著低于常规采烤,总糖含量显著高于其他两个处理;T_(1)处理烤后烟叶的外观质量和感官质量在3个处理中均为最优,烤后烟叶油分、柔软度、颜色和色度以及香气质、香气量均有提升;T_(1)处理产量低于其他两个处理,但烤后烟叶均价远高于另外两个处理,每房烤烟综合效益比T_(2)、CK分别高出1538.95、1089.40元。

Efficiency and Economy of a New Agricultural Rainwater Harvesting System

Shortage of water is the key limiting factor for agricultural development of Beijing.Rainwater harvesting(RWH) could provide an alternative water source for greenhouse agriculture,but local natural and socioeconomic conditions challenge the application of the technology.This article analyses the advantages and disadvantages of different types of greenhouse RWH in Beijing,and describes a new greenhouse RWH system demonstrated in 2008 in Huairou,a suburb district of Beijing.It analyses the efficiency,cost-benefit ratios and limiting factors of the new system.The results show that with the new system,RWH efficiency can be as high as 66%(of total rainfall) and the rainwater usage rate can reach 69% of total water usage.The ratio of benefit to cost of government investment can be 1.84,and the ratio of benefit to cost of a farmer's investment could be 1.68 provided the project is designed to save water and also increase income.However,the price of groundwater for agriculture directly influences the potential for applying and scaling up the project.If the RWH system does not increase the farmers' incomes at the current water price,they will not use it until the water price rises to a critical point,which is determined by external factors.This article also suggests a number of measures to increase the efficiency of the system in order to apply it on a large scale.

基于DCS技术的联合收割机作业路径控制研究

以联合收割机协同作业过程为研究对象,对多台联合收割机协同作业过程中的行进速度、作业幅宽及单台收割机作业成本等因素进行分析,提出了一种以收割成本控制为目标的联合收割机作业路径控制优化算法,并采用DCS技术搭建联合收割机系统作业调度控制系统。仿真实验结果表明:在协同收割作业时,收割机调度控制系统能够根据收割需求、按照最小收割成本进行联合收割机数量及收割机型的调度控制;收割机作业时,能够根据最优化路径进行作业,最大幅度地提高收割作业效率,同时确保收割作业成本最低。

Cost Minimization of Wireless Sensor Networks with Unlimited-lifetime Energy for Monitoring Oil Pipelines

Cyber-physical-system（CPS） has been widely used in both civil and military applications.Wireless sensor network（WSN） as the part and parcel of CPS faces energy problem because sensors are battery powered,which results in limited lifetime of the network.To address this energy problem,we take advantage of energy harvesting device（EHD） and study how to indefinitely prolong oil pipeline monitoring network lifetime by reasonable selecting EHD.Firstly,we propose a general strategy worst case-energy balance strategy（WC-EBS）,which defines worst case energy consumption（WCEC） as the maximum energy sensor node could expend for oil pipeline monitoring WSN.When the energy collected by EHD is equal or greater than WCEC,network can have an unlimited lifetime.However,energy harvesting rate is proportional to the price of EHD,WC-EBS will cause high network cost.To reduce network cost,we present two optimization strategies,optimization workloadenergy balance strategy（OW-EBS） and optimization first nodeenergy balance strategy（OF-EBS）.The main idea of OW-EBS is to cut down WCEC by reducing critical node transmission workload;OF-EBS confirms critical node by optimizing each sensor node transmission range,then we get the optimal energy harvesting rate in OF-EBS.The experimental results demonstrate that OF-EBS can indefinitely extend network lifetime with lower cost than WC-EBS and OW-EBS,and energy harvesting rate P in each strategy satisfies Pof-EBS≤P（OW-EBS）≤PWC-EBS.

Analysis of Rooftop Rainwater Harvesting in Kabul New City: A Case Study for Family Houses and Educational Facilities

The Afghan government has planned the project of Kabul New City (KNC) to cope with the rapid growth of Kabul, an existing capital city. Due to climatic and topographical reasons, it is supposed that KNC suffers from a water scarcity problem. This study investigates the feasibility of a rooftop rainwater harvesting system in KNC to relieve the water scarcity problem. An applicability of the rooftop rainwater harvesting system was discussed for several types of residential houses and schools, using 11 years rainfall data. This study also examined the cost-effectiveness of the system by considering the service life of the system. Furthermore, an optimal size of the rainwater storage tank was discussed based on the balance among harvested rainwater volume, non-potable water demand, and cost-effectiveness.

森林采运作业环境成本分析

为补偿森林采运作业对森林生态系统的经济效益与环境服务效能的负面影响 ,本文提出了森林采运作业“环境成本”问题 ,系统地分析了森林的经济产出与环境服务功能 ,总结了国内外森林环境服务功能价值的评价理论与方法 。

温室农业雨水集蓄利用工程规模优化

为了优化蓄水池最佳工程规模,该文通过构建雨水集蓄利用工程规模优化原理和方法,即工程效益最优法,并以北京某温室农业雨水集蓄利用工程为例对该方法进行了论证。研究结果表明地区日降雨规律以及集雨窖的规模对工程的集雨效率有很大影响,在降雨量、汇流总面积确定的情况下,集雨窖规模越大,可收集的雨量越多,但单位容积可收集的雨量随之减少;工程成本效益分析表明,设计日降雨量为25～40mm时,工程总效益/费用比值较高,全年可收集雨量与温室农业年用水量基本相当;在工程寿命期内,现有规模下的效益成本比值远低于最优规模时的效益成本比值。因此,适当降低集雨窖的规模可提高工程的经济性。该文论证的雨水集蓄利用工程规模优化方法能够为雨水工程的设计和应用提供理论依据和实践指导。

黄土高原西北部集雨水利用的投资与效益分析

以黄土高原西北部为研究区,通过中国科学院皋兰生态农业试验站2000-2001年雨水集流试验与春小麦、西瓜、西兰花和黄瓜的补灌试验,对各种集流场的年产流率和集流费用、蓄水窖(池)的贮水费用、作物产量和水分利用效率、以及各作物集雨微灌的投资、产值与单方水产值进行了比较分析。结果表明:各集流面平均集流费用和各蓄水窖(池)的平均贮水费用都很高,分别为1 07元/m3和5 08元/m3,且贮水费用显著高于集流费用。净产值和单方水产值的大小顺序依次为日光温室黄瓜、大田西兰花、砂田西瓜和大田小麦。如把人工计算在内,大田小麦不进行补灌,其净产值为负值,进而补灌导致了净产值的大幅度减小。集雨水用于微灌砂田西瓜、西兰花和日光温室黄瓜都能产生很好的经济效益。并提出了日光温室集水 贮水 高效用水的"一池一窖"模式。

4MG-275型自走式棉秆联合收割机作业成本分析

当前,在棉秆分散、收储季节性强、人工收集劳动强度大以及效率低等因素严重制约棉秆规模化工业利用发展的现状下,提出了开发4MG-275型自走式棉秆联合收割机的必要性;介绍了本设备的主要技术参数;分析了本设备的作业成本,并将其与传统人工收获方式进行了对比,得出了机械化收集的优越性,从而提出了利用机械化手段来支撑棉花秸秆规模化工业利用的必要性。

华北地区玉米机收籽粒与机收果穗性能及效益初析

华北地区玉米机收籽粒普及率非常低,人们对机收籽粒的认知水平不足。对玉米机收籽粒和机收果穗两种不同收获方式,从收获成本、时间、损失率、籽粒质量等多方面进行比较,结果表明,机收籽粒比机收果穗收获成本可以节省5.7%,时间可以节省50%以上,机收籽粒虽然破损率稍高(比机收果穗高6%),有待进一步改善,但是综合效果好,适合华北地区推广。

价格随供求变化经济捕获模型的定性分析

对单种群资源建立了一般生产函数下价格随供求变化的经济捕获模型,利用常微分方程稳定性和定性理论对该模型进行了定性分析,证明了系统极限环的不存在性,讨论了系统正平衡点的存在唯一性及其全局稳定性,并从生物经济学角度对主要结果作了解释,为生物资源的实际管理提供了理论依据。

具有密度制约和阶段结构的单种群模型

考虑了具有密度制约和阶段结构的单种群模型,通过动力学分析,得到了种群持久生存时捕获努力量应满足的条件、最大可持续产量下的最优捕获努力量.根据Gordon理论,以成年捕获系统为例,将机会成本、可变价格因素同时考虑,得到了政府应征税额度.

低成本省力化栽桑技术的研究进展

我国已育成了若干适合条桑育 ,适于扦插的桑品种及适于种子直播的杂交桑 ,为建立高密度低成本桑园打下了基础。研究推广了直接用袋接体 ,硬枝扦插和杂交种直播建园和初试了中晚秋条桑收获技术。今后的研究方向是选育发根性强 ,高产优质 。

海洋捕捞业与海洋生物多样性的持续有效发展——基于海洋生物经济学模型的分析

海洋捕捞业的经济有效性和海洋生物种群的保护是当前海洋渔业经济研究的重点,应该将相关海洋物种的捕捞和繁殖规律统筹考虑,提高海洋渔业资源的利用效率。通过对Flaaten的生物经济学模型的数理分析比较,提出经济鱼种的价格上涨并不会导致该鱼种生物种群存量下降,如果管理措施合理,鱼类种群存量依然存在上升的可能;并由此指出海洋捕捞必须考虑种群间相互关系,利用合理的生物经济学模型、建立明晰的海洋捕捞权等措施有助于海洋生物经济的持续有效发展。