原料基地的战略价值研究--期权定价模型的应用

在市场风险下 ,加工企业控制一定比例的原料供应 ,相当于购买了一种期权 ,这种期权对林工联合体有着不可忽视的战略价值 ,它可大大减少加工企业的市场风险暴露。本文应用期权定价模型对这种战略价值进行定量研究 ,敏感分析表明 :当木材市场价格水平、长期资本利率水平越高 ,木材价格波动率越大 ,加工企业拥有原料基地的战略价值越大。期权定价模型的应用为正确认识原料基地的战略价值 ,分析木材限额采伐政策等提供了良好的基础。     

柔性非光滑减粘脱附的自卸车模型试验研究

在柔性非光滑典型生物体表的仿生研究基础上，提出了一种自卸车装卸粘性土时解决其减粘脱附问题的新方法—柔性仿生减粘技术，对其减粘脱附作用进行了模型试验研究，优选了柔性仿生减粘技术方案，为在自卸车上的应用试验奠定了基础。     

对求解超静定结构几个问题的探讨

在对超静定结构进行分析计算时。常常会出现一些诸如“超静定次数判定”等问题。初学者往往对较复杂的超静定次数的判定感到无从下手。另外,本文对力法方程中的柔度系数做了进一步的探讨。     

Simulation of automatic control of an irrigation canal

Improved water management and efficient investment in the modernization of irrigation schemes are essential measures in many countries to satisfy the increasing demand for water. Automatic control of the main canals is one method for increasing the efficiency and flexibility of irrigation systems. In 2005, one canal in the irrigation scheme ‘Sector B-XII del Bajo Guadalquivir’ was monitored. This canal is representative of irrigation schemes in Southern Spain; it is divided into four pools and supplies an area of 5154 ha. Ultrasonic sensors and pressure transducers were used to record the gate opening and water levels at the upstream and downstream ends of each canal pool. Using the recorded data and the SIC (Simulation of Irrigation Canals) hydraulic model, two canal control options (local upstream control and distant downstream control) were evaluated using a PI (Proportional-Integral) control algorithm. First, the SIC model was calibrated and validated under steady-state conditions. Then the proportional and integral gains of the PI algorithm were calibrated. The controllers were tested using theoretical demand changes (constant outflow followed by a sudden demand increase or decrease) and real demand changes generated on the basis of a spatially distributed crop water balance that included a number of sources of variability (random and not random) in the determination of field irrigation timing and depth. The results obtained show that only the distant downstream controller was able to adjust quickly and automatically the canal dynamics to the varying water demands; it achieved this efficiently and with few spills at the canal tail, even when there were sudden and significant flow variations.     

仿生柔性非光滑表面减粘降阻的试验研究

对绒布,帆布、钢布,尼龙布,钢链等仿生柔性非光滑表面与田鼠毛皮、４５钢进行了法向粘附力和滑动阻力的对比试验。结果表明,在同样条件下,仿生柔性非光滑表面的粘附力是４５钢的１６％－４０％,滑动阻力是４５钢的３０％－５０％,具有十分明显的减粘附阻效果,为仿生柔性非光滑表面在工程技术上的应用开发创造了条件。     

基于ELES模型的广西城镇居民不同收入群体消费结构的对比分析

根据2009年《广西统计年鉴》中城镇居民家庭消费的截面数据,利用扩展的线性支出系统需求函数模型（ELES）,对2008年广西城镇居民消费结构、消费倾向和消费弹性进行了分析。结果表明,广西城镇居民呈现出较低的消费倾向,而且大部分居民消费还集中在衣、食、住等生存性消费方面,尤其是中、低收入家庭,这3项的消费支出占据了其收入的大半。在此基础上提出了扩大广西城镇居民消费需求的相应建议：应加大收入再分配的调节力度,努力缩小居民之间的贫富差距,促进整体消费水平的提升;培育广西居民消费热点,积极引导享受性消费。     

Numerical model of an aquaculture structure under oscillatory flow

Marine aquaculture is widely distributed in coastal areas. The aquaculture farms generate drag resistance to fluid motion and alter ambient hydrodynamics. Meanwhile, aquacultural structures are subjected to complex flow conditions including waves and currents. With the expansion to more open areas with severe flow field conditions, marine aquacultural structures face greater challenges and risks of damage. Culture unit is an important component of aquacultural structures and shows flexibility in both field observations and laboratory measurements. Underestimating or overestimating the drag resistance of culture units under the action of fluid flow can lead to damage risks or overdesign of the structure. A dynamic model is developed to estimate the deflection of flexible culture units and is incorporated into an aquacultural structure numerical model in this paper. Critical factors for safety as well as routine operation of aquacultural structures are considered including structural responses and mooring line forces. A suspended mussel long line system is taken as an example, and the results show that the calculated value (9.2 kN) of the maximum tension of the north mooring line is in good agreement with the measured data (9.8 kN) under the action of tide flow. The influence of different flow field parameters on structural dynamic responses is investigated. The numerical results indicate that decreasing wave height can reduce maximum mooring line tension and longitudinal and vertical motion amplitude of the main line. The maximum tension of the mooring line generally decreases with the increase of the angle between the main line and the inflow direction under the action of waves and tide flows. In structural design, the arrangement angle of structures can be determined according to the force calculation of mooring lines based on the numerical model. The spacing of culture units and the distance between adjacent long lines can be determined by referring to the motion calculation of structures to avoid damage due to intertwinement of structural components.     

旋切机上动力压辊正压力的计算

本文应用弹性理论中的虚位移原理计算木段挠度,使挠度等于0,从而确定单板旋切机上动力压辊装置的正压力等基本参数,并进一步确定动力压辊油缸尺寸,为动力压辊装置的结构设计提供重要的技术参数。     

乡镇土地利用总体规划的“刚性”与“弹性”问题探讨——以桃源县漳江镇为例

在桃源县漳江镇土地利用总体规划修编工作的基础上,对规划中存在的＂刚性＂与＂弹性＂问题进行了探讨,并且重点论述了两者结合的思路和方法等问题。