哈迪-温伯格平衡检验及其基因频率的估计

哈迪-温伯格平衡定律（Hardy-Weinberg equilibrium,HWE）是群体遗传学中最重要的原理,是群体有性繁殖上下代之间基因频率与基因型频率是否保持平衡的检验尺度。在HWE检验时通常需要对各基因频率作估计。研究了存在显隐性时基因频率的极大似然估计值的牛顿迭代算法,牛顿迭代算法的收敛速度快于EM算法;讨论了最小Pearson χ^2统计量估计与极大似然法估计的近似关系。推荐极大似然估计牛顿迭代法和最小Pearson χ^2估计法。     

市场化阶段的中国水产品供求问题研究

进入市场化改革体制之后,中国水产品供求关系从非均衡趋向基本均衡,凸现阶段性的供求结构和供求特性。文章首先通过对20余年的水产品供求演进及其背景分析,归纳出水产品供求特性;其次,构建水产品供求的计量经济模型,对其结构进行剖析;最后,从“食物体系”的观点论析水产品供求均衡动向,并为达成未来的供求均衡提出一些政策性建议。     

基于Nash均衡的多学科设计优化求解方法

结合Nash均衡理论,把各学科的设计目标作为博弈方,提出了一种易于解决冲突的多学科设计优化求解方法.各个学科可以采用不同的优化方法,并行地进行优化和设计;无系统协调模型,各个学科之间的信息交互简单.用实例证明了方法的有效性.     

基于Buck变换器的光伏发电系统MPPT 控制

研究由单个风险中性的供应商与多个竞争的损失厌恶零售商组成的两阶段供应链,在回购契约中考察竞争和零售商的损失厌恶态度对其最优订购决策和整个供应链协调性的影响.应用博弈论的方法,证明了该供应链博弈存在唯一的纯策略Nash均衡,而且竞争使得零售商的总订购量上升,而损失规避使得总订购量下降.竞争的存在削弱了损失厌恶效应对整个供应链协调性的影响.研究还发现,零售商的最优订购量随供应商的批发价增大而增大,随回购价格的增大而减少,并且在一定条件下回购契约可以使得供应链达到协调.     

落实“草畜平衡制度” 发挥草原生态服务功能——以甘肃甘南黄河重要水源补给生态功能区为例

由国家正式批准实施的甘肃甘南藏族自治州黄河重要水源补给生态功能区生态保护与建设项目,为保护已列入全国50个水源涵养区的海东——甘南高寒草甸草原水源涵养三级功能区迈出了坚实有力的步伐。但项目区由草原、森林和湿地组成的完整水源涵养体系,由于草原的退化、沙化和盐渍化(草原"三化")而严重受损。其中,草畜失衡是造成草原"三化"的主要根源之一。本研究在分析和论证草原"三化"及其生态功能衰退影响的基础上,强调应充分利用甘南黄河补水项目实施的绝佳契机,就如何落实草原"草畜平衡制度"提出了具体对策建议。     

Direct Measurement of CO2 Retention in Arable Soils with pH Above 6.5 During Barometric Process Separation Incubation

The barometric process separation(BaPS)technique is a well-established incubation method to simultaneously measure gross nitrification and respiration rates in soil.Its application,however,is still critical in soils with pH above 6.5.Here,a substantial part of microbial CO_2 production is retained in soil solution(CO_2,aq)due to shifts in the carbonate equilibrium.This may lead to substantial errors in gas balance calculation.Yet,utilization of the BaPS technique is only reliable if the critical term is adequately quantified.We present an easy,inexpensive,and direct method,the sterilization-CO_2-injection(SCI)method,to measure CO_2 retention during soil incubation.Sterilized soil was incubated in the BaPS system,and defined volumes of CO_2 were injected to stepwise increase CO_2partial pressure(p CO_2)inside the chamber and to analyse the physicochemical equilibration process.Five exemplary agricultural soils from Northeast China and Southwest Germany were used for method establishment,presenting pH values between 4.4 and 7.6 and carbonate contents between 0% and 3.9%.We observed that in soils with pH6.5,70%–90% of the injected CO_2 was taken up by the soil until the equilibrium inside the chamber was re-established.As expected,in soils with low pH(6.5),measured CO_2 retention was low.CO_2 retention patterns were sensitive to incubation temperature with tri-fold dissolution capacity at 5~?C compared to 25?C,but insensitive to variations in soil water content.The resulting soil-specific relationship between p CO_2 and CO_2,aq concentration allowed the quantification of CO_2,aq concentration as a function of headspace p CO_2.     

不同核背景的萝卜细胞质雄性不育与内源激素关系的研究

利用酶联免疫测定技术研究了萝卜金花薹细胞质雄性不育系75A和87A及其保持系75B和87B在花蕾中内源激素含量及激素之间平衡与不同核背景的关系。试验结果表明:不同核背景的不育系与保持系之间、不育系之间及保持系之间内源激素含量均有差异,除个别时期外,IAA和ZR含量为75B>75A、87A>87B、87A>75A和75B>87B;ABA和GA含量为75A>75B、87A>87B、75A>87A和75B>87B;此外IAA、ABA、ZR和GA之间的平衡也受到破坏。可见,萝卜雄性不育系内源激素的含量高低受核基因影响很大。     

流域尺度农业“水-土-经济”要素耦合机制与行为调控系统效应模拟

农业系统的“水-土-经济”要素是刻画人类活动与生态-水文过程互馈效应耦合的关键界面之一。本研究以局部均衡理论为依据，基于栅格尺度的水、土、作物的空间分布数据与行政区尺度的粮食生产、消费与贸易数据嵌套，构建了行政区-栅格跨尺度的农业部门局部均衡分析“水-土-经济”要素耦合模型（Water-Land-Economic nexus Model，WLEM）。研究以黑河流域“粮改饲”补贴政策为例，模拟种植与加工环节的农机设备补贴下水土资源消耗强度与空间布局的变化，刻画农业“水-土-经济”要素的耦合机制与政策干预下行为调控的资源消耗及经济产出的系统效应。模拟发现，对种植环节的大型农机补贴增加了非水土自然要素的投入，降低了生产成本，有助于增加青贮玉米种植面积。而对加工环节进行农机补贴，可通过提高青贮技术直接影响青贮玉米作为饲料的投入，与种植环节补贴相比，其对青贮玉米产量的拉动作用较大。种植与加工环节叠加补贴在鼓励青贮玉米生产的同时，一定程度减少了籽粒玉米种植面积，符合“粮改饲”政策目标。结果表明，在政策补贴过程中需重视加工环节的农业机械设备补贴，并完善种植补贴和加工补贴两种政策的优势互补机制。从生产和加工两个环节补贴的空间效益来看，青贮玉米与籽粒玉米在畜牧业投入上的竞争关系使作物种植过程中水土资源要素投入呈现出空间异质性特征，这与栅格尺度上水土资源要素作为农产品成本的占比以及要素供给和替代弹性差异直接相关。该研究为制定合理的水土资源配置方案与农业发展政策，实现流域水-生态-经济协同发展提供了科学依据。     

Analysis on the Quasi Monte-Carlo Method and its Application in the Slope Reliability

The critical reliability slip surface with minimum value of reliability index is difficult to be obtained by the Monte-Carlo method. The simplified Bishop method was adopted to calculate the factor of safety for given circular slip surface thereby defining the performance function in reliability analysis. Six variance values of random variables were designed and four sample ranges were assumed. A quasi-Monte Carlo method was defined with fow samples. One hundred and thirty-two potential slip surfaces were randomly generated. The reliability indexes regarding those slip surfaces were calculated by Monte-Carlo method and quasi-Monte Carlo method, respectively. The comparative results show that in the case of one random variable, the reliability index from Monte Carlo method is found to be linear with that from quasi-Monte Carlo method. In the similar conditions, the wider the sample range, the smaller the tangent value of line, and Vice versa. In addition, the bigger the sample number, the bigger the tangent value of line. The Quasi-Monte Carlo method is approved to be practicable for the determination of critical reliability slip surface for homogeneous slope.