客车车身振动仿真分析

首先建立了汽车车身结构的有限元模型,并进行了有限元计算模态分析;通过比较计算模态和试验模态,验证了车身结构有限元模型的正确性;基于模态分析的结果,提出了车身减振的改进方案,并且对改进前后的车身结构进行动态特性仿真分析,仿真分析结果表明,该改进方案能有效减轻车身结构的振动,可以作为控制车身振动,进而控制车内低频噪声的一条途径。     

基于PLC的挂面称重控制的设计

目前国内的大部分挂面包装都是由手工完成,只有很少一部分是用塑料热合包装,但采用塑料包装成本较高,而且易污染环境,同时热合包装为散包装,不利于运输。为了使包装设备自动化,采用三菱可编程控制器(PLC)、步进电机、称重传感器、A/D转换器及气压传动等实现电气控制,能与生产线配套作业,对挂面进行定量纸包装,克服了效率低、成本高、噪音大等缺点,并且具有很高的性价比。设备结构简单,体积小,生产成本降低,工作性能稳定,包装速度快,每分钟可达8.57kg,包装整齐牢固。     

不同供水量对绿豆苗期生物产量的影响

为研究供水量对绿豆的影响,确定适宜绿豆苗期生长的水分条件,在绿豆生长季节模拟降水量设4种不同供水量处理,测定绿豆苗期生长形态指标和各器官干物质积累。结果表明,供水量不足时,绿豆株高降低,叶片减少,地上部、地下部和总生物量均降低;绿豆虽然比较耐旱,适当增加供水量有利于苗期生长,综合长势和生物量,绿豆生长季节降水量350 mm比较适宜,绿豆地上部与地下部生长协调,各器官物质分配合理,为绿豆进一步分枝、结荚等生殖生长和提高经济产量奠定基础。     

甘蔗收获机切割系统负载压力影响因素的试验研究

针对甘蔗收获机在入土切割时无法根据地形精确控制切割器入土切割深度的问题,通过理论分析甘蔗收割机入土切割时影响切割系统负载压力的因素,并通过试验探究各因素对切割系统负载压力的影响规律。试验结果表明:影响切割系统负载压力的主要因素有入土深度、土槽进给速度、甘蔗密度、刀盘转速、土壤含水率和土壤密度,随着入土切割深度、土槽进给速度、甘蔗密度和刀盘转速的增加,切割系统的负载压力整体均呈逐渐增大的趋势,并得出各因素对切割系统负载压力影响的显著性及先后顺序。该研究为建立甘蔗收获机械切割系统的负载压力与切刀入土切割深度的关系数据库提供了数据支持。     

预切组合式香蕉茎秆粉碎还田机的设计

针对中国热带、亚热带农业区香蕉茎秆粗大、含水率高、富含植物纤维等特点,为解决香蕉茎秆粉碎过程中纤维缠绕严重、粉碎效果差的难题,设计了一种预切组合式香蕉茎秆粉碎还田机,并确定了该机的主要部件结构及总体方案。该机结构简单新颖、工作可靠、效率高,能够避免香蕉茎秆纤维对机具的缠绕,大幅降低劳动强度,适宜香蕉主产区的香蕉茎秆粉碎还田作业,有利于热区农业发展。     

农作物秸秆计量检测技术

中国是农业大国,秸秆资源的蕴藏量极其丰富。为实现农作物秸秆资源利用的最大化,必须对秸秆收集、储藏以及利用过程中各成分、物理特性的变化进行实时监测。因此,对农作物秸秆计量检测技术的需求不断增长,其研究和应用极具价值。介绍了中国农作物秸秆资源的现状以及秸秆的使用价值,主要针对秸秆水分含量、元素含量、木质纤维素含量以及热值这4种参数指标的计量检测技术进行了综述,同时也探讨了有关秸秆物理特性的检测方法。     

卷盘式喷灌机卷盘驱动负载计算与分析

为优化卷盘式喷灌机驱动结构,研制高效卷盘喷灌机驱动器,需要对卷盘式喷灌机的卷盘负载情况进行计算和分析。为此,以软管牵引式卷盘喷灌机为对象,建立了卷盘负载转矩计算的物理模型,理论推导了在运行时的卷盘负载转矩数学计算模型。以JP50和JP75型卷盘式喷灌机为例,按推导所得数学模型进行计算,得到了运行时卷盘负载转矩随已回卷PE管长度的变化规律和估计值。计算结果表明:JP50型卷盘式喷灌机运行时最大负载转矩约为960N·m,JP75型为6 001N·m;卷盘负载转矩随已回卷长度的增加而减小,且当卷盘回卷半径变化时,负载转矩将突然变大;负载转矩的大小和变化规律只与喷灌机的参数和运行条件有关,与运行时的速度无关。     

铵态氮素促进甘薯块根形成的解剖特征及其IbEXP1基因的表达

This study chose Shangshu 19 (S19) and Jixu 23 (J23) categorized by valid tuber root number per plant as analyzing varieties and arranged treatment combinations consisted of two nitrogen forms ammonium nitrogen (A_N) and amide nitrogen (X_N) integrated with two nitrogen rates 60 kg hm^-2 (L_N60) and 180 kg hm^-2 (H_N180), using field and pot trial assays, plus a check treatment received no nitrogen supply in order to make research on the anatomical observation on sweet potato tuber root differentiation and expression characteristics of IbEXP1 gene associated with tuber root formation in ammonia nitrogen in 2014 and 2015. Our results showed that the storage root yield of Shangshu 19 associated with more valid tuber root number per plant was significantly higher than Jixu 23 at harvest stage, which was significant difference compared with each other. In addition, nitrogen levels and nitrogen forms had significant interaction effects. The 60 kg hm^-2 ammonium nitrogen treatment in two sweet potato genotypes achieved the highest final storage root yield in field experiment and showed higher valid tuber root number per plant, which attributed to the younger tubers whose root diameter between 0.5 cm and 5.0 cm during the canopy closure period. It had been observed that 60 kg hm^-2 ammonium nitrogen treatment possessed the most vessels in the primary xylem bundle and the lignified parenchyma cells of the stele tissues in the pre-cambial period, followed with possessing high level expression of IbEXP1 gene, the biggest root diameter and stele diameter and the most number of primary and secondary xylem bundles in the course of primary cambium growth. As the vascular cambium was initiated, relative expression of IbEXP1 gene at 60 kg hm^-2ammonium nitrogen treatment and the degree of parenchyma cells lignification were intermediate between no nitrogen application and high nitrogen treatments, however, the diameter of root and stele and the ratio of them were highest, which achieved the perfect harmony in lignification and division of parenchyma cells in tuberization.     

Real Estate Administration by Internet

The government plays an important role in modern economic life. The administration by Internet is ranked first among the IT highway's five application areas. The author of this paper introduced the status of China's real estate administration by Internet, analyzed the problems existed and constructed a framework of real estate administration by Internet, which will facilitate China's real estate administration and modernization.     

Submicron Particles Sizing Methods and Measurement Techniques

Due to a series of wonderful characteristics, submicron particles are of high value in national economy, defense modernization and high technology fields, with wide application prospects. Submicron particle sizing methods and techniques are difficult problems in particle research field. Modern methods for particle sizing are stated and analyzed. Some problems are discussed when these methods are used for submicron particles.