拖拉机驾驶室的综合降噪

在对拖拉机驾驶室声学特性及噪声源进行分析的基础上,通过隔声、减振、吸声和控制部分噪声源等综合降噪措施,取得了降低驾驶员耳旁噪声１０．８ｄＢ（Ａ）的良好效果     

A Comparative Economic Analysis of Smallholder Cattle and Small Ruminant Production Systems in Botswana

Cattle rearing is the single most important activity in the agricultural sector of Botswana, and cattle enjoy a high status among both rural and urban dwellers. In recent years, farmers have begun to intensify the production of small ruminants owing to an increasing recognition by policy makers that they are a potential alternative source of farm income. However, as yet, small ruminants have not approached the social importance of cattle. This may be attributable to several factors, including economic considerations. The present study focused on the economic factor. It comprised a comparative economic assessment of cattle- and goat-rearing enterprises for an average smallholder farm-household to throw light on their relative economic efficiency. It was concluded that rearing either cattle or small ruminants is economically viable in the study area. The net profit measured as the net margin either per enterprise or per animal was far higher for a cattle-rearing enterprise. Nevertheless, when expressed in terms of the return on the capital invested in each enterprise, cattle rearing had only a slight edge (1.93%) over rearing of small ruminants     

六旋翼植保无人机飞行框架的结构设计与试验

为了达到无人机轻量化的要求，以碳纤维材质为机身主体，设计了一套六旋翼植保无人机的飞行框架。基于ANSYS对该框架关键结构部件的刚度和强度进行了静力学分析，根据分析结果，将单层中心固定板改为了双层结构并在机臂之间加入了加强筋。分析表明：优化设计后，无人机中心板形变量降低了104.36倍，最大应力降低了13.15倍，而质量仅增加了1.9%。最后通过实际飞行振动试验，基于LabVIEW对植保无人机机身3个不同位置竖直方向的振动信号进行小波变换降噪处理和时、频域计算评估，振动最大RMS值为1.69 g，小于飞行控制系统振动报警阈值2.5 g，表明其在稳定性和操控能力上具有良好的表现。     

基于模糊理论的城市交通生态环境综合评价模型研究

根据城市交通生态环境系统的复杂性,对影响城市交通生态环境质量的指标因素进行提炼,确定了指标因素的隶属度函数,建立了基于不同模糊算子的城市交通生态环境质量多阶模糊综合评价模型.针对合肥市4条道路的交通环境质量监测数据,利用建立的评价模型,采用不同的模糊算子进行分析优化.此模型也可用于其他城市交通生态环境质量的评价.