泉州平原作物生长季和夏旱期降水量叠加预测模式及其应用

采用时间序列分析方法，对最能代表整个泉州平原降水情况的晋江气象站１９６０～１９９６ 年共３７ ａ 中３～１１ 月（作物生长季）和７～９ 月（夏旱期）２ 段时间的降水量资料进行统计，同时分析了该地区的降水量变化规律，获得了该地区上述２ 段时间的降水量模式，进而提出了防御干旱的措施，     

Annual weather variability and its influence on the population dynamics of Calanus finmarchicus

The reaction of the population of Calanus finmarchicus to relatively extreme annual cycles of weather in the North Sea was investigated by one-dimensional model simulations. A population dynamics model for C. finmarchicus was coupled with a physical and a biological upper-layer model for phosphate, phytoplankton and detritus to simulate the development of the successive stages of C. finmarchicus. Observed annual weather cycles were used to drive the physical water column model, the results of which were then input to the plankton model. The simulations yielded the temporal development of all stages of C. finmarchicus over an annual cycle in terms of numbers and weights. Compared with the results reported for 1984 by Carlotti and Radach (1996; Limnol . Oceanogr . 41: 522–539), it appears that the temporal range for the occurrence of the peak concentration of C. finmarchicus may be 2 weeks in the northern North Sea. The simulated variability is in accordance with observations. Years with more continuous primary production such as the year 1984, which was cloudy and windy during the summer, may then provide the optimum conditions with respect to producing an abundance of zooplankton during the following year.     

基于PLUS空间决策模型的城镇与农业空间协调布局优化

正确处理好农业空间与城镇空间之间的矛盾，对保障国家粮食安全、促进城镇可持续发展具有重要意义。该研究以江西省赣州市南康区为例，应用GIS技术，在耕地与建设用地适宜性评价的基础上，引入PLUS模型、凸壳模型预测城市扩张范围及类型，初步划定城镇开发边界与永久基本农田布局，并根据城市发展规律和冲突矛盾协调原则，对永久基本农田和城镇开发边界进行优化。结果表明：1）南康区综合质量高的耕地主要集中于唐江镇、镜坝镇、凤岗镇等乡镇；建设开发适宜性评价综合得分由高到低呈现出中心城区向四周乡镇圈层式扩散的分布情况，东山街道、蓉江街道的分值最高。2）PLUS模型预测至2035年南康区新增建设用地为3362.85 hm²（其中城镇建设用地2023.06 hm²），凸壳模型得出南康区扩张类型属于外延型，蓉江街道和东山街道是未来城区扩张发展的重点区域。3）以耕地国家利用等平均值为标准，将农业空间划分为保护区、储备区与一般耕地，当城镇开发边界与保护区发生空间冲突时，调整城镇开发边界，优先保护农田；当城镇开发边界与储备区、一般耕地发生空间冲突时，调出农田，保障城镇发展。研究结果可为耕地资源保护提供参考，为永久基本农田与城镇开发边界优化协调提供借鉴。     

Patterns and drivers of seasonal water sources for artificial sand-fixing plants in the northeastern Mu Us sandy land, Northwest China

Understanding plant water-use patterns is important for improving water-use efficiency and for sustainable vegetation restoration in arid and semi-arid regions. However, seasonal variations in water sources and their control by different sand-fixing plants in water-limited desert ecosystems remain poorly understood. In this study, stable isotopic ratios of hydrogen (δ²H) and oxygen (δ¹⁸O) in precipitation, soil water, groundwater, and xylem water were determined to document seasonal changes in water uptake by three representative plant species (Pinus sylvestris var. mongolica Litv., Amygdalus pedunculata Pall., and Salix psammophila) in the northeastern Mu Us sandy land, Northwest China. Based on the depth distribution and temporal variation of measured gravimetric soil water content (SWC), the soil water profile of the three species stands was divided into active (0.01 g g^-1 < SWC < 0.08 g g^-1, 20% < coefficient of variation (CV) < 45%), stable (0.02 g g^-1 < SWC < 0.05 g g^-1, CV < 20%), and moist (0.08 g g^-1 < SWC < 0.20 g g^-1, CV > 45%) layers. Annually, P. sylvestris, A. pedunculata, and S. psammophila obtained most water from deep (59.2% ±9.7%, moist layer and groundwater), intermediate (57.4% ±9.8%, stable and moist layers), and shallow (54.4% ±10.5%, active and stable layers) sources, respectively. Seasonally, the three plant species absorbed more than 60% of their total water uptake from the moist layer and groundwater in the early (June) dry season; then, they switched to the active and stable layers in the rainy season (July–September) for water resources (50.1%–62.5%). In the late (October–November) dry season, P. sylvestris (54.5%–66.2%) and A. pedunculata (52.9%–63.6%) mainly used water from stable and moist layers, whereas S. psammophila (52.6%–70.7%) still extracted water predominantly from active and stable layers. Variations in the soil water profile induced by seasonal fluctuations in precipitation and groundwater levels and discrepancies in plant phenology, root distribution, and water demand are the main factors affecting the seasonal water-use patterns of artificial sand-fixing plants. Our study addresses the issue of plant water uptake with knowledge of proportional source-water use and reveals important implications for future vegetation restoration and water management in the Mu Us sandy land and similar desert regions around the world.     

畜群规模的结构决策研究

结构和规模是影响草地放牧生态系统功能实现的重要因素。本文通过建立和分析畜群种群动态模型， 揭示了母畜结构参数是影响畜群规模唯一因素的一般规律：（１） 当１２ ∑ｒｉ＝ １ｂｉ ∏ｉｊ＝ １ ｑｉ，ｊ－ １ｐｉ，ｊ－ １ （１ － ｓｉ，ｊ－ １）（１ － （１ － ｑｉ，ｊ－ １） ｐｉ，ｊ－ １ （１ － ｓｉ，ｊ－ １）） ＝ １ 时， 畜群规模稳定， 基本保持不变；（２） 当１２ ∑ｒｉ＝ １ｂｉ ∏ｉｊ＝ １ ｑｉ，ｊ－ １ｐｉ，ｊ－ １ （１ － ｓｉ，ｊ－ １）（１ － （１ － ｑｉ，ｊ－ １） ｐｉ，ｊ － １ （１ － ｓｉ，ｊ－ １）） ＜ １ 时， 畜群规模呈下降趋势，最终趋近于零；（３） 当１２ ∑ｒｉ＝１ｂｉ ∏ｉｊ＝ １ ｑｉ，ｊ－ １ｐｉ，ｊ－ １ （１ － ｓｉ，ｊ－ １）（１ － （１ － ｑｉ ，ｊ－ １） ｐｉ，ｊ－ １ （１ － ｓｉ，ｊ－ １）） ＞ １ 时， 畜群规模随年度不断膨胀， 并最终突破系统的承载能力。     

基于BTO多目标遗传算法的播种机性能优化设计

受播种地形和地域的影响,大部分播种机的播种质量、播种效率和能耗不能发挥到最佳状态,为了提高播种机的作业性能,深入挖掘了按顾客订单生产(Build-to-Order,BTO)模式的一般性意义,并将该模式引入到了播种机的优化设计中,提出了一种基于BTO模式的多目标速度控制遗传算法优化模型。根据播种质量、效率和能耗的要求,首先确定了BTO模式下播种机性能优化的初始参数,利用多目标函数确定了播种机的速度控制模型,并利用遗传算法进行了优化设计。最后,通过试验样机对播种机的播种性能进行了测试,结果表明:使用多目标遗传算法对播种机的性能进行优化后,播种机的播种质量、播种效率和播种能耗有了明显的改善,为新型播种机的研发提供了较有价值的参考。     

Thermal degradation modeling of flexural strength of wood after exposure to elevated temperatures

Abstract

Wood is being used heavily in single-family residential dwellings. Therefore, it is important to categorize their response when exposed to elevated temperatures for a sustained period of time. An important aspect of structural fire design is to assess postfire residual strength of existing structures. This study addresses this issue by developing models to predict strength degradation of wood after exposure to elevated temperature. The objectives were to (a) study the effect of exposure time on bending strength [Modulus of Rupture (MOR)] of wood at elevated temperatures, (b) interpret any relationships between different temperature and time of exposure using kinetics and a statistical approach, and (c) compare the two approaches. Two hundred thirty-two samples in total were tested in flexure as a function of exposure time and several temperatures. MOR of wood decreased as a function of temperature and exposure time. Rate of degradation was higher at higher temperatures. These results were fit to a simple kinetics model, based on the assumption of degradation kinetics following an Arrhenius activation energy model with apparent activation energy of 37.4 kJ/mol. A regression-based statistical model was also developed. The kinetics-based model fit the data better with one less parameter and predictions consistently matched the observed values, making the model preferred over the regression approach.     

能源价格促进能源效率提升的实证分析

基于向量自回归模型,通过协整分析、Granger因果检验、脉冲响应分析和方差分解分析,实证研究了能源价格与能源效率之间的关系。研究结果表明:从长期来看,中国能源价格的上涨能促进能源效率的提升。从短期来看,中国能源价格的上涨是促进能源效率提升的原因,但反之不成立。能源价格的正向冲击会促使能源效率提升,这种效应在短期内增长较快并能够长期保持。     

基于智能手机平台的猪饲料配方系统设计与实现

设计依猪只个体日龄、体重等参数而异的饲料配方是实现猪精细饲养的关键，目前已有很多具备此功能的饲料配方软件，但它们大多数基于PC平台。结合智能手机便于携带、可移动性好等优点开发的基于智能手机平台的猪饲料配方软件，便于携带且操作简单，使用NRC1998模型精确预测了猪营养需要量，配方结果更准确科学，饲料原料营养成分数据用XML文件贮存，数据读取方便，有效地降低了系统开发成本。     

基于网络平台的农民技术教育新模式

系统总结了宝鸡市农民技术教育网络平台建设的最新进展,基本实现了卫星电视网络、计算机网络和省市县乡村五级办学体系网络的有机结合,具有天网、地网和体系网＂三网合一＂的特征,初步形成了现代化、开放式的农民技术教育新模式。深刻分析了新教学模式的几条实现途径及其在农民技术教育中的优势和潜力,根据存在的主要问题,有针对性地提出了网络环境下大规模、高性能地开展农民技术教育的对策。