共查询到19条相似文献，搜索用时 281 毫秒
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一种新的农机折旧计算方法--定值递减法 总被引：3，自引：0，他引：3
针对余额递减法和双倍余额递减法存在的局限性,提出一种新的农机折旧方法－定值递减法。该方法既保持了余额递减法连续按比例递减,及折后余值和实际残值吻合的优点,又具有双倍余额递减法的某些特点。通过理论推导和实例验证,说明该方法是可行的。 相似文献
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基于双倍余额递减法的转换点规律，提出机械设备在折旧率是直线折旧的m倍时的高倍修正余额递减数学模型，并论证了残值为零时的转换点规律。 相似文献
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农业机器折旧中的双倍余额递减法改进研究 总被引：5，自引：0，他引：5
给出机器折旧费提取应满足的条件及其数学表达式。在此基础上，指出了双倍余额递减法一般数学模型的不足，并对它进行了改进，同时探讨了改进后的计算方法的规律性，最后进行了实例计算。 相似文献
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折旧是一定时期内(日、年)固定资产磨损价值转移到产品成本中去,以补偿固定资产所损耗的价值。随着社会经济的全球化发展,机械设备余额递减加速折旧的方法得到越来越广泛的使用。在此建立广义的余额递减法通用模型,提出了既适合于高倍余额递减法,又包含曾经已用的余额递减法和双倍余额递减法的模型,为农业机械费用的合理计算提供理论基础。 相似文献
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大中型拖拉机折旧方法选择的研究 总被引：1，自引：0，他引：1
以50种大中型拖拉机的样本数据为研究对象,采用双样本假设检验法对现有的大中型拖拉机的折旧方法进行了比较分析。给出了动态余额递减法更符合经济规律、金融规律和成本核算的原则,其次是动态双倍余额递减法、动态平均年限法的结论。通过对动态余额递减法和残值模型进行差异性分析后得出用动态余额递减法计算所得的折旧额和残值模型预测值都很接近,50个验证样本的折旧值与残值模型的预测值偏差均在±10%以内,验证样本最大偏差为5.59%,尤其是在经济寿命(3071.74～3334.24小时)之前,39个验证样本的折旧值与残值模型的预测值的最大偏差为-2.96%。进而确定动态余额递减法是最好的折旧模型。 相似文献
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水利行业固定资产折旧方法的合理选择 总被引：2，自引：0，他引：2
针对我国水利行业固定资产折旧现状，从其特点出发．对水利行业固定资产折旧方法的合理选择进行了分析研究，并提出了具体计算方法——动态余额递减一直线复合折旧方法。该法有利于水利行业固定资产的合理回收．从而保障水利行业的可持续发展。 相似文献
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提出了一种预测横流式风机内部流场的方法，适用于任意形状的叶片和涡壳。该方法假设流体无粘性，不可压缩，流动为二元流动，采用直接边界元法和离散旋涡法相结合的方法来计算风机的内部流场，同时考虑了涡室上部壁面边界层的影响。为了满足开尔文定理，叶片后缘处有尾涡放出，尾涡的运动用离散旋涡法计算。实际计算了两种不同涡壳的风机。 相似文献
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在对现有文献研究的基础上，对适时性损失计算中作业期最佳分布主其证明方法又作了进一步探讨，指出了单项作业时作业期最佳分布定理的局限性，并对其进行了修正。同时对有两项关键作业期最佳分布证明方法进行了剖析，指出了其存在的不足，并给出了一种新的证明方法。 相似文献
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横流式风机内部流动的研究 总被引：4，自引：1，他引：4
提出了一种直接边界元和离散旋涡法相结合的数值解析方法并对横流式风内部流动进行了计算，该方法不仅考察了叶轮的作用，同时也考虑了叶轮的作用，同时也考虑了涡室的影响。实测了横流式风机的内部流场并与计算结果作了比较，结果表明，该方法可望于流体机械的民。 相似文献
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农业机器动态折旧的研究 总被引：3，自引：0，他引：3
提出农业机器折旧应遵循等值原则，并运用资金时间价值分析法，给出了动态折旧的一组公式，省去了固定资金占用费的计算，化简了固定资金回收方法，保证了资金的足额回收 相似文献
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结合现有的折旧方法，研究了CAl090型货车折旧规律，为货运企业以及有运输部门的企业进行成本核算和固定资产评估提供依据。 相似文献
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Field experiments were conducted for 2 years to investigate the effects of various levels of nitrogen (N) and methods of cotton planting on yield, agronomic efficiency of N (AEN) and water use efficiency (WUE) in cotton irrigated through surface drip irrigation at Bathinda situated in semi-arid region of northwest India. Three levels of N (100, 75 and 50% of recommended N, 75 kg ha−1) were tested under drip irrigation in comparison to 75 kg of N ha−1 in check-basin. The three methods of planting tried were; normal sowing of cotton with row to row spacing of 67.5 cm (NS), normal paired row sowing with row to row spacing of 35 and 100 cm alternately (NP) and dense paired row sowing with row to row spacing of 35 and 55 cm alternately resulting in total number rows and plants to be 1.5 times (DP) than NS and NP. In NS there was one lateral along each row, but in paired sowings there was one lateral between each pair of rows. Consequently the number of laterals and quantity of water applied was 50 and 75% in NP and DP, respectively, as compared with NS in which irrigation water applied was equivalent to check-basin.Drip irrigation under NS resulted in an increase of 258 and 453 kg ha−1 seed cotton yield than check-basin during first and second year, respectively, when same quantity of water and N was applied. Drip irrigation under dense paired sowing (DP) in which the quantity of irrigation water applied was 75% as compared with NS, further increased the yield by 84 and 101 kg ha−1 than NS during first and second year, respectively. Drip irrigation under NP, in which the quantity of water applied and number of laterals used were 50% as compared with drip under NS, resulted in a reduction in seed cotton yield of 257 and 112 kg ha−1 than NS during first and second year, respectively. However, the yield obtained in NP under drip irrigation was equivalent to yield obtained in NS under check-basin during first year but 341 kg ha−1 higher yield was obtained during second year. The decrease in N applied, irrespective of methods of planting, caused a significant decline in seed cotton yield during both the years. Water use efficiency (WUE) under drip irrigation increased from 1.648 to 1.847 and from 0.983 to 1.615 kg ha−1 mm−1 during first and second year, respectively, when the same quantity of N and water was applied. The WUE further increased to 2.125 and 1.788 kg ha−1 mm−1 under DP during first and second year, respectively. The agronomic efficiency of nitrogen was higher in drip than check-basin during both the years when equal N was applied. The WUE decreased with decrease in the rate of N applied under fertigation but reverse was true for AEN. It is evident that DP under drip irrigation resulted in higher seed cotton yield, WUE and AEN than NS and also saved 25% irrigation water as well as cost of laterals. 相似文献
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农业机器经济寿命计算的研究现状及其分析 总被引：3，自引：2，他引：1
对现有文献给出的农业机器经济寿命计算方法，按追求的目标进行了分析归纳，认为应分为３类，其基本的计算方法有４种。在此基础上，分别给出了各种计算方法的通用数学模型，进而对其进行了分析，指出了目前研究存在的一些问题。 相似文献
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本文按照生产费用和耗能之和最小的原则,利用抛物线函数关系,对微灌系统干、支管的水力坡降进行了分析。分析结果表明:影响经济坡降的主要因素有流量、电价、系统的使用寿命、年运行时间、价格系数、以及机械效益等。最后并举例说明了该公式的应用。 相似文献
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Yield, water and nitrogen-use response of rice to zeolite and nitrogen fertilization in a semi-arid environment 总被引：1，自引：0，他引：1
Water scarcity and soil nitrogen (N) loss are important limitations for agricultural production in semi-arid region especially for rice production. Zeolite (Z) as a soil conditioner can be used to retrain water and nitrogen in near-surface soil layer in lowland rice production system. The objectives of this study were to investigate the effects of different application rates of natural zeolite (clinoptilolite) and nitrogen on rice yield, yield components, soil nitrogen, water use, water productivity in a silty clay soil in 2004 and 2005. Zeolite was only applied in the first year. In order to study the long-term and continuous effect of zeolite on the objectives of the study, no zeolite was applied in the second year and the study was conducted on the same land as the first year. Zeolite and N were applied at rates of 0, 2, 4, and 8 t ha−1 and 0, 20, 40, and 80 kg ha−1, respectively in 2004. In 2005, each plot received the same amount of N as received in 2004. It is concluded that by decreasing N application rates, higher Z application rate is needed to improve grain yield. Highest grain yield was obtained at N application rate of 80 kg ha−1 and Z application rate of 4 t ha−1. Higher grain yield was mostly attributed to lower unfilled grain percentage and higher 1000-grain weight that were a result of higher N application rate and N retention in soil due to Z application. Nitrogen and Z applications resulted in higher grain protein contents and nitrogen recovery efficiency (NRE). Based on these results and due to higher N retention in soil under Z application, improved grain yield quality, nitrogen-use efficiency (NUE), and nitrogen recovery efficiency (NRE) could be obtained at Z application rate of 8 t ha−1 and N application rate of 80 kg ha−1 or more. However, this was not satisfied for NUE. Moreover, it is found that at higher N application rates lower Z application rates are needed to effectively retain soil residual mineral nitrogen. Furthermore, at N application rates of 80 kg ha−1 or more, Z application increased soil water retention and resulted in lower seasonal water use and higher water productivity. In general, it was concluded that the effect of Z application in retaining soil N was also effective in the second year. 相似文献
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D. Bar L.W. Tauer G. Bennett R.N. González J.A. Hertl H.F. Schulte Y.H. Schukken F.L. Welcome Y.T. Gröhn 《Agricultural Systems》2008
This study discusses and demonstrates the construction and application of a specially structured dynamic programming replacement and insemination optimization and simulation model of the dairy cow that includes detailed representation of repeated episodes of clinical mastitis (CM). The application determined optimal individual cow decisions, which were then compared with mastitis culling rules of thumb to determine the deviation of these rules from optimality. Calculation of break-even values of applying a preventive measure to reduce CM incidence or severity in the form of two fictitious mastitis vaccines were also carried out. Model input parameters were based on data from five large dairy herds in New York State (about 16,000 lactations), but these parameters can be easily changed for other types of dairy operations. To demonstrate the usefulness of this model to assist individual cow CM treatment options, the cost of the decision to cull a third lactation cow, six months after calving, with the first case of CM, was negative $3 USD for a low milk producing open or pregnant cow (i.e. cull), and positive $850 USD for a high milk producing and pregnant cow (i.e. treat even with extremely high treatment cost). Compared with the model recommended optimal policy, a rule of thumb decision to routinely treat all cows with a first case of CM resulted in an additional cost of $2 per cow per year, a very low deviation from optimality and suggests all cows should be given a second chance. A policy of replacing all CM cows after their second CM case after treatment of the first CM incident resulted in an additional cost of $27 per cow per year. If the decision was to replace all cows only after their third CM case this cost estimate was $8. The cost-benefit of applying two fictitious vaccinations showed that a vaccination reducing the milk loss caused by Gram-negative CM by 50% had a break-even cost of $14 per cow per year. A vaccination that would result in additional reduction of the risk of CM by 50% had a break-even cost of $37 per cow per year. 相似文献