【摘要】 机群的服务规模不同,经济效益也不同。单位面积上机械作业的可变费用基本上为一常数,而分摊的固定费用则随服务面积的增大而减小。经过推导,单位面积上的机械作业费与服务面积间的关系图形为一双曲线。另一方面,关键作业项目若不能在适时期内完成,亩产量将受到损失,推导出的单位面积净产值与服务面积间的关系图形为一抛物线。在同一坐标图上,一般可得出两曲线的两个交点,交点对应的面积即为该机群服务范围的上下限,两曲线间的垂直距离表示单位面积的纯收益,也可在同一坐标图上用曲线Y表示,最大垂直距离的面积为最佳服务面积,此时Y=max。将全部可供选择的机群的Y曲线绘出后,对于给定服务面积A,可查出各机群对应的Y值,其中最大值所对应的机群,即为面积为A时的合理机群结构。本文用解析方法对上述思路作出推导,并用河北省晋县的实例对八种机群及不同规模进行了计算,得出不同规模时的配备方案,与晋县实际情况相当吻合。更多还原

【Abstract】 Profits of certain farm machinery group for variable service areas are also differeat. The variable machinery cost per unit area can be conceived as constant, while the fixed machinery cost per unit area will be drop down as the service area grows up. The. relationship between the machinery cost and service area can be shown as hyperbolic curve on coordinate diagram. If the essential farm op-eration can’t be performed in the due time period, timeliness loss will occur, the yield will drop. This paper derived analytically the relationship between the net production value per unit area and the service area. This relationship can also be shown in the same diagram as parabolic curve. This curve usually intersects with the said hyperbola at two points,the abscissas of these points indicate the lower and upper limit of the service areas of given machinery group, the perpendicular distances between two curves represent the net income per unit area. This net income can also be drawn as a curve Y on the same diagram. The poin ta twhich Y = max shows the optimum service area. Calculate and draw all the Y-curves for every possible machinery group, from these cur-ves, we can find a series values of Y for a given service area. Within these Y values, there will be a max. value, which is on the curve corresponding to reasonable machinery group for given area A. This paper derived all these me-ntioned calculating methods analytically. These methods are applied to Jia County, Hebei, on eight machinery groups for nine different service areas. The results of calculations on the machinery equipments are pretty close to the present real situations.更多还原