Design of PID control algorithm on large diameter tiled-grating

To realize the long-time dynamic stability for the tiled-grating control system,a PID algorithm based on the analysis of the four-dimensional degree of freedom mathematical model for the tiled-grating is developed. Two improvements are made in incremental PID algorithm. The latches compensation method is used to avoid saturated loss,and the four-point center difference method is applied to avoid interference. The splicing spot photos of the tiled-grating’s closed-loop control experiments demonstrate that the tiled-grating which employs the improved PID algorithm can acquire a long-time stability as well as the stability can keep one hour.     

可降解育苗容器成型机的研制

阐述了可降解育苗容器成型机的结构、工作原理及设计要点。该机采用一体化设计,实现基质输送、容器成型、基质装填、育苗容器切割一次完成。摒弃传统的螺杆出料方式,创新性地采用电磁震动、自重落料的方式实现装填成型,解决了采用螺杆出料方式的容器成型机工作时易堵塞基质、故障率高的技术难题。该机对装填的育苗基质含土量无限制,可实现不同土壤含量育苗容器的装填成型,可广泛应用于林木、果蔬和花卉的育苗容器生产。     

我国天然橡胶进口贸易波动因素分析——基于恒定市场份额模型

在运用恒定市场份额模型（CMS模型）对2000--2011年间我国天然橡胶进口贸易波动的成因进行了实证分析。结果表明：国内宏观经济决定的天然橡胶进151引力是左右我国天然橡胶进口贸易的核心因素;世界经济因素与我国天然橡胶进口贸易的发展密切相关;不合理的进口商品结构影响着我国天然橡胶进口贸易。     

基于GIS的2010年中国人口分布与耕地利用状况研究

根据2010年全国分县行政区划电子地图、第六次人口普查结果等数据,运用地理信息系统和理论性演绎分析等手段分析中国人口分布、流动趋势与耕地利用情况.结果表明,2010年中国人口分布特点为东密西疏,东南部人口密中有疏,西北部人口疏中有密,人口分布格局没有明显变化,人口集中程度高;2000 ～2010年全国人均耕地面积由0.103 hm2/人下降到0.091 hm2/人,耕地利用率下降,同时不同海拔阶梯地区农业生产效率不同,第二阶梯最高,第三阶梯最低;人均耕地面积的减少使得人口压力增加,第三阶梯人口压力明显高于第一、二阶梯,在农业生产效率提高的因素下第三阶梯地区人口会向较低人口压力的第一、二阶梯地区流动,即中国东南半壁范围向西北方向扩散.     

苹果绵蚜试验种群的建立

为明确苹果绵蚜接种单株苹果苗后的定殖、扩展过程机制。在严格控制的条件下,选择3a生矮化红富士苹果苗,分别单株接蚜1、3、5、10、15、20和25头,观察苹果绵蚜在入侵定殖时种群繁殖和扩散情况。结果表明,除单株接蚜1、3头外,其他处理均能定殖成功,且接蚜量与种群数量达到最大值所需要的时间呈显著线性相关,连续阴雨天气对苹果绵蚜种群数量有明显抑制作用。以成蚜为初始种群,当单株接蚜15头以上时定殖可能性较大,并随接蚜量增加,种群具有更高的稳定性。     

设施蚕豆群体结构消长的影响因素

研究了不同架膜时间、播期和密度三因素对鲜食蚕豆品种通鲜2号群体结构消长的影响,结果表明:(1)单因素:随架膜时间的推迟,单株分枝数增加;随播期的推迟,单株分枝数减少;随密度的增加,单株总分枝数和一、二级分枝数减少,三级分枝和无效分枝数则相应增加。(2)双因素互作:同一架膜时间,随密度的增加,单株总分枝数及一、二级分枝数减少,无效分枝增加;随播期的推迟,单株各类分枝数均减少。同一播期,随架膜时间的推迟,一级分枝数减少,其他分枝数均增加;随密度的增加,单株各类分枝数均减少。同一密度,随架膜时间的推迟,单株一级分枝数减少,其他分枝数均增加;随播期的推迟,各类分枝数均递减。(3)三因素互作:在相同架膜时间、相同密度下,随播期的推迟,单株分枝减少;在相同架膜时间、相同播期条件下,随密度的增加,单株分枝数减少;在相同播期、相同密度下,随架膜时间的推迟,单株分枝数减少。     

A mathematical model of the dynamics of Mongolian livestock populations

Subsistence livestock herding is an important component of livestock production in Mongolia. However, pasture degradation, extreme weather, desertification, livestock overpopulation, infectious diseases and limited government support increasingly threaten this livelihood. To better assess these afflictions, understanding the population dynamics of livestock is critical. Towards this goal, we developed a model of Mongolian livestock populations. Using the Leslie–Gower difference equation competition model, a discrete analog of the continuous Lotka–Volterra 2-species model, Mongolian livestock population dynamics were simulated in MATLAB. The model encompasses four species and is stratified by age and sex. Calibration of parameters is accomplished using official population data from 1970 to 2010; a turbulent time period that includes the socialist to capitalist market transition and two growth periods both followed by two dzuds (severe winter storms). Herders were surveyed and herd structures were sampled for parameter and model initial value estimation. The current model simulates the Töv aimag (province) goat, sheep, cattle and horse populations. However, with more data collection, the intention would be to simulate all species populations in any aimag or soum (province subdivision). A ten-year simulation of future livestock populations predicts a more than two-fold increase in goat and sheep populations, a slight increase in cattle populations and a slight decline in horse populations. Preliminary validation with 2011 population data shows accurate estimation. Furthermore, a stable future livestock population was attained with the implementation of more than double the current culling rate. The model can be integrated in infectious disease transmission modeling, used as a tool for predicting the economic potential and support requirements of the livestock sector and used to illustrate the urgency of fostering sustainable management of livestock populations in Mongolia. This story of Mongolian pastoral life presents an excellent opportunity to study a social-ecological system as well as to contribute in creating a sustainable, healthy and efficient Mongolian livelihood.     

仙翁山国家森林公园蝶类资源调查

仙翁山国家森林公园地理环境优美,生物资源丰富。通过多年对仙翁山国家森林公园中蝶类进行资源调查,共采集蝶类55属、73种共1 235只。通过调查掌握了仙翁山国家森林公园蝶类的种群结构,分析蝶类发生与环境的相互关系,可为分析黑龙江省东部地区蝶类资源提供了技术参考。     

25个油棕SSR标记的开发及应用这些标记评估油棕资源的遗传多样性

应用NCBI网站上公布的EST序列,挖掘SSR位点,并根据SSR位点的侧翼序列设计引物,对18份油棕资源的DNA进行了PCR扩增,扩增结果显示,在72对引物的PCR扩增中,25对引物具有多态性特征,并且其杂合度在0.1049和0.6605之间,平均杂合度为0.4702,这暗示了这些标记具有中度的多样性。同时,应用这些有多态性的标记评估了这些油棕资源的遗传多样性和群体结构,分析结构显示:椰子研究所油棕资源圃的遗传多样性最为丰富,此外,聚类分析表明不同位置来源的油棕资源展现了显著的遗传差异。本研究开发的SSR标记将能被应用到油棕的遗传育种研究中。     

强制性与自发性:农村生态环境忧思——苏南S村与皖中Z村的对比研究

通过对苏南S村和皖中Z村进行实地调研,采用半结构式访谈和文献分析法,厘清了这2种"生态村"类型对生态环境产生的正面或负面影响,并提出了构建"生态村"的2种范式。