基于模型切换的复杂多模型系统的建模与仿真原理

针对动力学系统的复杂性,引出了多模型的概念,提出模型自动切换的方法,论述了基于模型切换的复杂多模型系统的建模与仿真原理,并给出了在液位控制及五模型系统中的应用实例。     

PDM中一种有效的访问控制方法

实现高效可靠的访问控制是构建PDM系统的基础。本文讨论了PDM系统常用的访问控制模型及其优缺点,提出了一种基于角色——对象的访问控制模型,并说明了笔者在具体系统中实现该模型的设计思路、实现方法。该方法有效地实现了PDM系统的访问控制,增强了系统访问控制管理的灵活性和方便性。     

基于B/S和UML的网上考试系统建模

以网上考试系统的开发为背景，探讨了UML在网上考试系统建模中的应用，在对系统进行需求分析的基础上，用Rose构建了系统的需求模型、对象结构模型、行为模型和实现模型．     

基于链系统的酒精精馏控制技术的研究

针对酒精脱水制取过程中存在的温度流量等因素变化的滞后性、扰动性以及系统动态特性的复杂性等问题,利用链系统原理,建立了结构分散化的控制模型.通过分析无水酒精的制取过程,找出了酒精精馏脱水过程的基本控制关联关系,建立了一个拥有4个单元模型、2条控制关联链和2支链间关联的链系统模型,设计了无水酒精制取过程的链预估算法和控制系统模型.并进行了系统仿真.     

基于能量的包含OLTC的电力系统励磁控制研究

利用Hmihon函数方法,对基于能量的非线性微分代数系统控制进行了阐述,提出了非线性微分代数系统Hamihion实现步骤。建立了详细的发电机模型、励磁控制系统模型和OLTC模型。并利用Hamilton结构,完成了镇定控制器的设计。通过MATLAB仿真,证明了系统的稳定性。     

基于Simulink的经编机电子横移系统仿真

为解决经编电子横移系统电气与机械特性差异所导致的系统优化困难问题,根据电子横移系统的控制原理,分别对系统的各个部分进行建模,包括伺服驱动与电机模型、信号调节与反馈模型、机械传动机构模型,再通过传递函数的输入输出关系,建立了经编机电子横移系统的整体仿真模型。并使用MatLab/Simulink对仿真模型进行验证与对比,根据系统阶跃响应的仿真振荡逐渐收敛且迅速趋于稳定,验证了模型的准确性与系统的稳定性。为进一步优化系统的动静态特性,以速度调节器参数为例,分析不同速度比例增益下的系统阶跃响应,结果表明：增大速度比例增益有利于提高电子横移系统的动态响应性,但当增益增大到一定值,则会使系统振荡而无法使用。     

面向云计算平台的系统使用率的能耗模型分析

为了对云计算系统的能耗进行优化,文章提出了一种基于系统使用率的云计算平台能耗模型,并对其具体构建与设计进行了分析,测试结果表明该能耗模型可以有效降低系统能耗。     

基于ADAMS建模的浮筏隔振系统仿真研究

利用ADAMS软件与有限元软件相结合,建立刚柔耦合浮筏隔振系统模型。文章以功率流作为浮筏隔振系统的性能评价指标,研究了该模型在不同参数条件下的隔振性能,并与理论仿真结果进行对比分析,验证了模型的可靠性。对于构建复杂筏架的浮筏系统有一定的参考价值。     

定量系统的自适应Smith预估计偿控制

解决大延迟系统问题的经典Smith预估器要求系统的模型是精确的,否则由于模型偏差带来的补偿效果很差.本文记述在纸张生产过程中,应用自适应的Smith预估器进行定量控制,其补偿效果较好,有效地减小了定量系统模型偏差所带来的影响.     

基于IDEF的人力资源系统数据模型

针对重庆齿轮箱有限责任公司企业资源计划CCERP系统,采用IDEF0进行人力资源系统功能建模,用IDEF1x进行人力资源系统信息建模,开发了人力资源系统管理软件.给出了人力资源系统的功能模型、信息模型和具体实现方法.运行结果表明:依据所建立的人力资源数据模型开发的人力资源管理系统具有一定的实用价值,解决了企业手工管理人力资源的难题,提高了管理效率.     

Synergistic effects of insect-resistant maize and Teretrius nigrescens on the reduction of grain losses caused by Prostephanus truncatus (Horn.)

Prostephanus truncatus is a pest that causes serious losses in stored maize (Zea mays L.) especially in developing countries. This research was conducted to investigate the use of post-harvest insect resistance maize in combination with biological control of P. truncatus by the predator Teretrius nigrescens to reduce maize storage losses. We studied the population dynamics of P. truncatus with and without a predator in combination with susceptible maize and resistant maize to insects under laboratory conditions. This study confirms that P84c3 is a resistant variety against P. truncatus. Maize resistant kernels had a reduction of 30% losses in comparison with susceptible kernels. Significant and favorable interactions were observed between P84c3 maize and presence of T. nigrescens. A dramatic reduction of 80% in progeny number, 81% grain weight loss, and 75% frass production caused by P. truncatus was observed when the predator was used in combination with P84c3. Resistant maize reduced the prey development time and consequently the insect density allowing the predator to control more effectively the population. Prey/predator proportion on resistant maize was significantly higher in comparison with susceptible kernels; thus, giving a more effective pest population control by the predator. These results demonstrated that the combination of post-harvest insect resistance maize with the predator T. nigrescens reduces grain maize losses by P. truncatus.     

不同采收方式对雪茄烟上部叶晾制效果的影响

  目的  为了解不同采收方式对雪茄烟上部叶晾制效果的影响。  方法  以H382为实验材料,于海南五指山试验点设置了3种采收方式:带茎采收、一次性采收和逐片采收,研究不同采收方式对雪茄烟上部叶晾制过程中含水率、多酚氧化酶活性、多酚类物质含量、淀粉酶活性及内在化学成分的影响。  结果  （1）上部叶一次性采收烟叶含水率在晾制过程中较适宜烟叶生命活动的进行,逐片采收烟叶失水过快而带茎采收失水过慢。（2）晾制过程中以一次性采收烟叶PPO活性较好,带茎采收烟叶PPO活性较高,逐片采收烟叶PPO活性较低,均不利于烟叶品质的提升。（3）晾制结束后烟叶绿原酸、芸香苷和莨菪亭含量以一次性采收处理较高。（4）化学成分如烟碱、两糖比、钾氯比等以一次性采收烟叶中较为协调。  结论  相对于带茎采收和逐片采收,上部叶一次性采收可有效提高酶促棕色化反应对雪茄烟叶的有利影响,避免烟叶发黑,提高烟叶品质。      

周期logistic脉冲收获系统的优化控制策略

研究一类由周期logistic模型描述的种群系统的脉冲优化控制问题．在给定时刻对种群同时进行比例和常量脉冲收获,在系统保持周期变化的前提下,考虑收获成本因素,以最大经济净收益为目标,研究收获努力量及收获常数对收益的影响,并确定最优的脉冲收获控制策略．利用关于脉冲微分系统的极值原理和一些分析技巧,获得了最优控制策略及最优收益的确切表达式．     

一类具有Beddington-DeAngelis功能反应捕食系统收获模型的稳定性

研究一类具有双线性密度制约及Beddington-DeAngelis功能反应的捕食系统收获模型.运用微分方程定性稳定性理论讨论系统正平衡点的性态,得到其局部渐近稳定及全局渐近稳定的充分条件,利用Pontryagin最大值原理得到系统的最优收获策略.     

一种小型辅助人力甘蔗收割装置

目前我国的甘蔗收割仍靠人工,为了减轻人工收割甘蔗的劳动强度和提高效率,本文设计了一种小型的脚带式辅助人力收割甘蔗的装置。收割人员可通过下踩装置上的踏板达到剪切甘蔗的目的,代替了弯腰收割甘蔗的动作。本文对该装置进行了虚拟分析,以solidworks建模为基础,对装置进行了力、关键部件、位移分析,进行了样机的设计验证。     

Effects of Combine Harvesting on Head Rice Yield and Chaff Content of Long and Short Grain Paddy Harvest in Sri Lanka

Paddy harvesting is the process of collecting the mature rice crop from the field which consists of activities such as cutting, handling, threshing and cleaning. Cutting, threshing and cleaning plays an important role to reduce postharvest losses. Lower performance of traditional harvesting process, labour shortage, reduced turn-around time and use of high yielding varieties have inevitably forced farmers to shift into mechanical grain harvesting in Sri Lanka. Rice milling is carried out to produce an edible polished or white rice product from harvested rough rice. Head rice yield is considered for marketing purposes because broken rice has low price in the market. Field survey was conducted in Polonnaruwa, Ampara and Hambanthota districts to identify most popular types of combine harvesters operating in the above districts. Paddy samples were collected from harvest of two most popular models of combine harvester in triplicate. Paddy sample of 1m² area from every paddy field were harvested separately by manual harvesting followed by manual threshing and cleaning in laboratory as control sample of relevant paddy field. Moisture content of the paddy grains were measured in the paddy field using digital moisture meter before harvesting. Paddy samples were subjected to sun drying until the moisture content come down to 14±1% before the quality analysis in the laboratory. Each paddy sample was analyzed for moisture content, chaff percentage and head rice yield percentage (HRY). Paddy was milled using laboratory scale rubber roll sheller and abrasive polisher. Chaff content percentage was measured by adding 100 ml of paddy to water and volume of chaff was measured using graduated cylinder. HRY was calculated dividing the weight of grain partials, which are larger than the ³/₄ of the grain, by weight of paddy sample. HRY between the two combine harvesting machine models evaluated were not significantly different at p<0.05 and also it was not significantly dependent on the harvesting methods such as combine harvesting and manual harvesting. The chaff content was significantly higher in model-2 in comparison to control sample for long grain paddy while model-1 was not significantly different with control sample for short grain paddy.     

2种甘蔗收割机在甘蔗收获中的应用

国内甘蔗机械收割的应用与国外相比存在较大的差距。通过引进国外的甘蔗收割机,并在国内进行应用探索,分析不同甘蔗收割机的收割能力、除杂能力、对宿根的影响及成本,为甘蔗收割机在国内的应用提供参考,以加快国内甘蔗机械化收割的应用。     

油菜机械收获配套农艺技术研究：Ⅰ．不同油菜品种机械收获损失的差异

本文系统地研究了四个油菜品种在机械收获过程中各部位损失量的差异。结果表明：四个油菜品种机械收获损失主要发生在脱粒和清选过程中,占总损失量的80％左右;抗裂角性强的油菜品种可减少自然脱落和割台的损失,但增加了脱粒过程的损失;高产品种虽然机械化收获的损失量最高,但总收获损失率却最低。     

Research on New Technology of Fiber Flax Harvesting

Modifications of combine harvester were introduced. Flax harvesting with the modified combine harvester following the dessication with Roundup did not affect the yield and weight of flax seeds when compared to the conventional pulling harvesting. A new method lead to a reduction in the yield of homomorphic fiber but losses depend on the cutting height and with the normal plant heigh (over 700 mm) and stubble height below 80 mm could be reduced to less than 10%. Flax harvesting by mowing can reduce the total labor costs by 30% and the labor costs of harvesting by more than 42%. Mowing of fiber flax fiber can significantly reduce and simplify the entire production technology.     

我国整秆与切段2种甘蔗收获方式发展历程与前景分析

进入21世纪以来,甘蔗机械化收获技术在我国得到重视和发展。尽管整秆式收割机技术水平和可靠性在逐步提高,几家生产该类收割机的厂家仍相继陷入停产危机。进口切段式收割机价格昂贵,在我国使用中作业效率低,国产切段式收割机在性能和可靠性方面与进口同类机型还存在较大差距。甘蔗收割机生产企业、科研单位、甚至政府决策部门都面临着我国甘蔗收获技术应如何发展的困惑。本文在综述国内外甘蔗收获技术发展历程的基础上,结合我国甘蔗生产立地条件和经营模式,分析了整秆式与切段式2种技术路线在我国的发展前景,并提出相关建议。