Economic Viability of Smallholder Agroforestry and Beekeeping Projects in Uluguru Mountains, Tanzania: A Cost Benefit Analysis

Agroforestry and beekeeping are widely promoted as prospective Nature- Based Income Generating Activities (NIGAs) to improve livelihoods while at the same time enhancing biodiversity conservation in degrading agro-ecologies. These activities can diversify and increase famers’ incomes and support instinctive biota and fauna resilience. However, evidence to showcase and compare their long-term benefits is scant. We use the case of Uluguru Mountains in Tanzania to evaluate and compare viability of agroforestry and beekeeping projects using the Cost Benefit Analysis (CBA) approach. The results of analysis yielded positive NPVs for both agroforestry and beekeeping projects at discount rates not higher than 8.2% and 8.5% respectively. Overall, the comparison of economic viability between agroforestry and beekeeping projects revealed that the former was relatively more profitable than the later in terms of both the NPV and Benefit Cost Ratio (BCR) criteria. However, the Internal Rate of Return (IRR) for beekeeping was slightly higher than that of agroforestry. Yet, we underscore the fact that these two projects can jointly be implemented to enhance livelihoods of farmers and support biodiversity conservation in the study area and other parts with similar agro-ecologies in developing countries. However, farmers in these agro-ecologies need to be supported by governments and non-government development partners in terms of training and inspiration to shift from orthodox farming to sustainable NIGAs.

Benefit-cost analysis of raising Pinus wallichiana seedlings in different capacities/sizes of root trainers in the nursery

Modern nursery methods of seedling production in different sized root trainers, were compared by raising seedlings of Pinus wallichiana involving costs incurred and benefits received. In order to provide a common basis for the comparisons, the study involved the raising of 1000 seedlings annually on a continuous basis for seven years. A relative economic analysis of raising P. wallichiana seedlings in 300, 150 and 100 cm^3 root trainers was carried out and we estimated that the root trainers of 300 cm^3 capacity recorded the highest total input cost of Rs. 35571 and Rs. 40018 for 1000 seedlings produced annually at discount rates of 12% and 6%. Seedlings raised in 100 cm^3 root trainers recorded the lowest total input cost of Rs. 23390 and Rs. 27737 per 1000 seedlings annually at discount rates of 12% and 6%. Hence, returns per rupee invested in raising seedlings in the 100 cm^3 root trainers accounted for the maximum benefit-cost ratio （i.e., 1.56 and 1.61） at discount rates of 12% and 6%. Thus seedlings raised in 100 cm^3 and 150 cm^3 root trainers were found to be most cost effective when compared with seedlings grown in 300 cm^3 root trainers. The results can be attributed to the larger number of cells per tray （higher growth density） in the 100 and 150 cm^3 root trainers, compared to the number of seedlings in the 300 cm^3 root trainers.

Operation Benefit of Fruit Dealers in Shizishan Street Farm market

This paper mainly discussed the operation benefits of fruit dealers in farm market. Taking fruit dealers in Shizishan Street Farm market in Wuhan City as the research object,this paper introduced current operation situation of fruit dealers and made a descriptive statistical analysis on characteristics of operators,operation situation,and cognitive status. Besides,it introduced the concept of net cost-benefit ratio to reflect the operation benefits. From further analysis on the operation benefits of fruit dealers,it found that there is little difference in the costbenefit ratio between dealers in the farm market. The average net cost-benefit ratio was 11. 94%. Specifically,if the total cost is 100 yuan,the dealer can obtain 12 yuan net profit. In order to find out how cost factors affect the operation benefits,it established a regression model for cost factors and net cost-benefit ratio. According to the survey results,when the wholesale cost increases 10000 yuan,the cost-benefit ratio will increase by 1. 454 percentage points,thus increasing the wholesale investment is helpful for increasing the net cost-benefit ratio; when the loss cost increases 10000 yuan,the cost-benefit ratio will increase by 7. 501 percentage points,thus the dealers can increase the operation benefits through controlling the loss cost and reducing the operation cost. Finally,it came up policy recommendations from the perspective of government and operators.

新业态从业人员参加养老保险的成本收益与收入再分配效应——基于共同富裕视角

基于个人和社会角度,意在探讨哪种参保选择能同时满足个人的“成本收益”效应最大化和社会的“收入再分配”效应最大化,以达到推进共同富裕的效果。采用2018年中国劳动力动态调查微观数据(CLDS),构建精算模型研究发现:新业态从业人员基本养老保险全覆盖可使养老金成本收益比增加,使养老金基尼系数减小;养老金成本收益比随城职保参保率提高而增大,基尼系数随城职保参保率提高而减小;提升城职保参保率与增加缴费指数相结合的政策可以发挥更大的成本收益效应和收入再分配效应。为实现共同富裕的伟大目标,应加快推进新业态从业人员社会保险全覆盖,鼓励新业态从业人员参加城职保。

住房价格与养老保障水平对人口出生率的影响——基于2019~2023年我国省际面板数据的实证分析

目的:基于孩子成本——效益理论,分析住房价格与养老保障水平对人口出生率的影响,为提高我国生育水平,推动我国人口长期均衡发展、优化人口结构提出对策建议。方法:利用2019年~2023年31个省的宏观数据,采用房价收入比和基本养老保险覆盖率作为住房价格和养老保障水平的衡量指标,通过面板固定效应模型进行实证分析,考察住房价格与养老保障水平对人口出生率的影响。结果:基准回归结果表明,作为生育成本的房价收入比(β=-0.201,P<0.001)和作为生育保障收益替代的基本养老保险覆盖率(β=-11.832,P<0.001)对人口出生率都有显著的负向影响,加入双向固定效应后的结果与基准回归结果保持一致。异质性回归结果表明,住房价格与养老保障对人口出生率的影响会因城镇化率和养老金发放标准的不同存在差异。结论:我国应当通过调控房价收入比、改革基本养老保险制度、加强正确婚恋观和家庭观引导以及均衡教育与医疗资源等措施,增大生育收益与成本之差,提高生育意愿和人口出生率。

基于全寿命效费比的地铁上盖隔震(振)结构优化设计方法

隔震(振)技术是提升地铁上盖建筑抗震性能和舒适度的有效措施,优化此类结构设计方法具有现实意义和紧迫性。提出了适用于地铁上盖隔震(振)结构的全寿命效费比评估模型;采用基于结构响应的全寿命评估方法,研究了周期比、质量比、隔震层刚度及阻尼等关键结构参数对地铁上盖隔震(振)结构效益的影响;基于遗传算法提出了地铁上盖隔震(振)结构优化设计方法。研究结果表明:增加隔震层后结构地震损失主要集中于下部结构,上、下部结构质量比越大地震损失越小;上下部结构周期比越大,地震损失越小;隔振层刚度与隔振效益呈正相关;采用提出的优化算法对原型结构优化后,地震损失费用可减小30%,竖向振动加速度级可减小2 dB,验证了该方法的可行性。

基于性能和寿命周期成本的路面预防性养护措施选择

为践行《广东省“十四五”干线公路养护管理提升行动方案》,在归纳总结近年来高速公路沥青路面预防性养护成功经验的基础上,结合某高速公路沥青路面实际技术状况检测结果,探索以养护措施性能和寿命周期费用为指标的最佳预防性养护方案的确定方法。研究结果有益于完善全寿命周期效益最优的公路养护科学决策体系,规范现有高速公路预防性养护措施选择程序,为高速公路预防性养护方案和施工图设计提供科学依据。

基于遗传算法的路网级桥梁养护与安全分析

随着交通网络的发展和桥梁结构的老化,养护工作变得更加重要,而传统的养护决策存在工作繁琐、效率低下的问题。因此,研究提出建立桥梁安全风险分析体系,并借助带精英策略的非支配排序遗传算法进行路网级桥梁养护决策。试验结果显示,研究方法在150次迭代后完成收敛,共得出100种有关竹埠港湘江大桥养护的决策。选择其中具有代表性的决策进行分析,考虑次要结构时最优决策经费为252万元,效益费用比达到0.99,不考虑次要结构的最优决策经费为129万元,效益费用比为1.60。且养护后撞击力降低了44.91%,吸收撞击能量提高了38.13%。研究为路网级桥梁的养护与安全风险分析提供了系统、科学的方法,对于提高桥梁养护效益、减少养护成本,以及确保桥梁结构安全具有积极意义。

Dry Season Feeding Technologies: Assessing the Nutritional and Economic Benefits of Feeding Hay and Silage to Dairy Cattle in South-Western Uganda

South-western Uganda annually experiences prolonged drought that results in dramatic drop in milk production of dairy cattle. This study was conducted to assess the nutritional value and economic benefits of feeding silage and hay to dairy cattle in the sub-region. The cross-sectional study covered seven districts with 105 farmers interviewed during the wet and 45 others in the dry season. Up to 88 soil samples were collected and analyzed for soil texture, soil pH, organic matter and total Nitrogen, Phosphorus, Potassium, Calcium, Sodium and Magnesium. Likewise, 148 forage (105 fresh, 25 silage and 18 hay) tissues from 21 pasture species were collected and analyzed for nutritional values. Using a questionnaire, data on production costs and milk revenues were collected for cost-benefit analysis. Results showed that silage of Napier grass treated with molasses (10.2 MJ/kg) and hay of naturally established pastures (10.6 MJ/kg) had the highest metabolisable energy (ME) values, while the lowest (8.30 MJ/kg) was for star grass. Hay of star grass presented the highest level of crude protein (21.4%) with maize (corn) showing the lowest (9.38%). Digestibility of hay of naturally established mixed pastures was the highest (64.4%), followed by that of silage of Napier grass treated with molasses (62.0%), while star grass hay had the lowest (52.6%). With exception of silage made from maize, all the other six forms of silage had a good crude protein (CP) content. Regardless of the good CP content (≥9.9%), all silage untreated with additives was poor in quality since its ME was less than 9.9 MJ ME/kg and ration digestibility less than 67%. Nonetheless, feeding of silage and hay increased milk yield and farm productivity with a benefit-cost ratio of 5.5 and 2.7 for silage and hay respectively.

2001—2020年我国甜菜成本收益动态演变与原因探究

本文基于《全国农产品成本收益资料汇编》的单位面积成本和收益数据,采用趋势分析法和比较分析法探究了2001—2020年我国和新疆、内蒙古、黑龙江三个主产区甜菜总成本和收益的变化规律,进一步探究了甜菜成本收益动态演变的驱动因素。结果表明:(1)2001—2020年我国甜菜总成本逐步提高,2018年达到高位后有所回落,20年年均增长率为7.45%,从成本增长的绝对数额来看,物质与服务费用和人工成本居前两位;从年均增速来看,地租和人工成本增速居前两位。(2)2020年物质与服务费用、劳动力成本、土地成本分别占甜菜总成本的45.33%、35.76%和18.91%。(3)从三个主产区20年成本均值看,新疆总成本最高、内蒙古其次、黑龙江最低;单产由高到低依次为新疆、内蒙古、黑龙江;从甜菜成本内部结构来看,新疆物质与服务费用占比最高,内蒙古人工成本占比最高,黑龙江土地成本占比最高。(4)三大主产区总成本总体呈上升趋势,新疆、内蒙古增量明显高于黑龙江;而黑龙江增速最快、内蒙古其次。(5)我国甜菜成本利润率呈先增、后降、再震荡回升态势,经历了三个周期和一个未完成周期,2011年达到最高,2016年处于最低,近20年成本利润率均值为26.51%,2020年成本利润率约为9.53%。(6)内蒙古化肥投入数量呈现先增(2010—2017年)后降(2018—2020年)态势,化肥农药“零增长”政策在内蒙古初现效果。(7)成本收益变动的主要影响因素包括劳动力成本和物质与服务费用快速增加,使得甜菜比较效益不高,异常气候频发、重迎茬和除草剂残留问题影响单产和甜菜收益,副产品综合利用不高,甜菜种子价格偏高且主要依靠进口。这些研究结论为推动我国甜菜产业高质量发展提供现实依据。

基于含权k-壳分解的分组教学虚拟网络映射算法

提出一种两阶段的基于含权k-壳分解的分组教学虚拟网络映射算法。该算法根据含权k-壳分解法对底层网络进行预处理,然后沿着节点间的最短路径映射链路,并结合分组教学优化模型的分组、教学、自学与互学的优化策略,实现节点和链路的协调映射,从而进一步提高解的质量。仿真结果表明,所提算法作为一种多目标的虚拟网络映射算法,能够有效减少链路开启量,提升虚拟网络请求接受率及长期收益成本比。

Cassava Groundnut Intercropping: A Sustainable Land Management Practice for Increasing Crop Productivity and Organic Carbon Stock on Smallholder Farms

Cassava-groundnut intercropping is not a common practice among smallholder farmers in Sierra Leone even though both crops are well suited for intercropping. On-farm trials were conducted in three locations (Bai Largor, Bassah, and Njala Kanima) in the Moyamba district during the 2021 cropping season to investigate the efficacy of cassava-groundnut intercropping for increasing crop productivity and soil organic carbon stock on smallholder farms in the Moyamba district, Southern Sierra Leone. The experimental design was a randomized complete block design in three replications with treatments of sole groundnut, sole cassava and cassava-groundnut intercropping. Data on the yield and yield components of cassava and groundnut were analysed using the PROC MIXED procedure of SAS 9.4 and means were compared using the standard error of difference (SED). The above-ground biomass, number of roots per plant, and fresh root yield of cassava were not significantly (p > 0.05) affected by the cassava-based cropping system. Averaged across locations, intercropping cassava with groundnut decreased the above-ground biomass, the number of roots per plant, and fresh root yield of cassava by 17%, 11%, and 17%, respectively. The above-ground biomass, number of pods per plant and fresh pod yield of groundnut were significantly (p 1), the highest net revenue and benefit-cost ratio. The benefit-cost ratio was also favourable for the sole cassava (BCR > 1) but not favourable for the sole groundnut (BCR < 1). Averaged across locations, intercropping cassava with groundnut increased the benefit-cost ratio by 121% and 13% when compared to the sole groundnut and sole cassava. In the event of a 40% yield loss for the cassava and groundnut, the benefit-cost ratio was favourable (1.12) only for the cassava groundnut intercropping system. The net soil organic carbon stock was favourable only for the cassava-groundnut intercrop. Averaged across locations, the net soil organic carbon for the cassava-groundnut intercropping increased by 3.4% when compared to the baseline within one cropping cycle of the cassava (12 months). The results confirm that cassava-groundnut intercropping is a sustainable land management practice that could enhance crop productivity and soil organic carbon stock on smallholder farms.

分布式光伏发电并网的成本/效益分析

在全球节能减排、能源安全的巨大挑战下,发展可再生能源成为推动后危机时代经济转型、发展低碳经济的重要手段。而国家发改委发改价格[2013]1638号文的出台,使众多光伏企业看到了国内市场开始启动的迹象。文章分析了目前国内光伏发电的主要运营模式,提出分布式光伏发电并网的经济性评价流程,建立了不同运营模式下光伏发电的全寿命周期成本/效益计算方法与模型,并分析了不同运营模式下分布式光伏发电的两种并网设计方案。最后综合考虑运营管理模式、发改价格[2013]1638号文规定的补贴方式,对某实际案例进行成本效益分析。结果表明,对于分布式光伏发电项目,电价补贴方式的成本效益优于建设补贴方式,因此发改价格[2013]1638号文的出台,必将激励国内光伏市场的启动。研究成果有助于解决光伏发电并网成本效益的问题,为光伏发电并网及运营管理模式等相关配套政策的制定奠定理论基础。

峰谷分时电价的成本效益分析模型及其应用

针对“厂网分开”后我国电力市场的现状分析了与峰谷分时电价相关的各方成本和效益,分别建立了电网公司、电力用户、发电公司和全社会的成本效益分析模型,并详细介绍了成本效益分析的计算流程。算例分析结果表明利用所提出的成本效益分析模型可得出确保各参与方的益本比均大于或等于1的“削峰填谷”电量临界值。研究成果可为各参与方分析峰谷分时电价方案的可行性提供参考。

北京市新生儿乙肝疫苗免疫策略成本效益分析

目的 分析北京市新生儿乙肝疫苗免疫策略所取得的经济效益。方法 以北京市疾病预防控制中心报告资料为基础 ,采用在自然人群中分层多级抽样和医院内随机抽样相结合的方法 ,收集HBV感染相关肝病患者和表面抗原携带者作为费用调查的对象 ,运用成本效益分析方法进行综合评价。结果 现行北京市新生儿乙肝疫苗免疫策略使得 1992年出生的新生儿 90 776人一生中避免发生急性乙肝 1779例、慢性乙肝 15 0 7例、乙肝后肝硬化 381例、肝癌 12 4 4例、表面抗原携带 335 9例。可获得 85 83 37万元的净效益 ,效益成本比为 13 33。结论 北京市新生儿乙肝疫苗免疫策略可获得巨大的经济效益 ,应继续巩固和完善该策略。

高剂量乙肝疫苗免疫策略成本效益分析

目的 探讨我国经济发达地区乙肝疫苗接种的最佳免疫策略。方法 以北京市东城区防疫站 1991～ 1998年乙肝疫苗免疫接种及乙肝发病、死亡资料及费用调查为基础 ,对新生儿高剂量的免疫策略进行成本效益分析。结果 1991年对全部新生儿实施预防接种 ,投入疫苗接种成本 34 2 4万元 ,因免疫接种而避免急、慢性乙肝及肝癌而节省费用 5 91 79万元 ,可获 4 99 2万元的净效益 (NB) ,效益成本比 (BCR)为 15 5 8。结论 现行免疫接种方案经济效益显著 ,建议经济发达地区仍实行高剂量免疫策略。

基于风险量化的事故备用容量协调分配方法

备用容量在区域电网间如何分配将影响电力系统的可靠性和经济性。基于此研究了备用配置方案的风险量化评价指标,进而提出了一种计及成本效益比的电网事故备用容量风险量化协调分配方法。该方法首先分析了区域成本效益比、功率缺额事故发生概率、备用成本、缺电成本等因素对系统备用分配的影响,并对事故备用配置及备用配置不足所带来的风险分别进行了量化,然后基于量化结果重新分配区域电网的事故备用容量。最后基于IEEE 118节点系统进行了仿真计算,验证了本文所提方法的有效性和合理性。

玉米秸秆蒸汽爆破用于厌氧发酵的技术评价

蒸汽爆破可破坏木质纤维素结构,提高纤维素、半纤维素的转化利用率,是秸秆类物质利用的一种有效预处理方式。作者研究了玉米秸秆蒸汽爆破处理及其厌氧发酵过程中的能量平衡关系,结果表明相同维压时间下蒸汽爆破处理后玉米秸秆厌氧发酵过程中的能源转化率随着压力增大而增大,而在相同压力条件下均在90s维压时间时得到最大能源转化率。玉米秸秆蒸汽爆破后在常温条件下厌氧发酵的最小和最大能源转化率分别为8.39%和11.68%,是对照组的1.38倍和1.92倍。但对蒸汽爆破玉米秸秆厌氧发酵的增量效益-费用比分析表明,因玉米秸秆蒸汽爆破处理而引起厌氧发酵产气量增加所形成产气的能量增加量小于蒸汽爆破处理所消耗的能量,从能量转换角度来说蒸汽爆破并不是玉米秸秆厌氧发酵的最经济处理方式。

基于区间数和价值理论的配电网可靠性评估

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