Using landscape suitability models to reconcile conservation planning for two key forest predators

Protection of area-limited species is an important component of plans to conserve biodiversity, but the habitat needs of such species can be different and important habitats may not align with existing reserves. We used empirically derived landscape suitability models for the spotted owl and the fisher to evaluate the overlap in habitat suitability for these two old forest-associated predators in an area of northern California affected by the Northwest Forest Plan (NWFP), a bioregional conservation plan. The area includes designated Wilderness areas and new reserves (Late-Successional Reserves, LSRs) established under the NWFP. We used the site selection algorithm MARXAN to identify priority habitat areas for each species, and for both combined, and to compare these areas with reserves. Sites were selected under two constraints, to achieve a threshold proportion of total habitat value and to select new areas equal to the total current area in existing reserves. The rank correlation between predicted value for the two species was low (0.11), because areas of highest predicted habitat value were more widely distributed for the owl. This difference also meant that the sites selected to optimize habitat value were more aggregated for fishers than owls, resulting in greater overlap of owl habitat and current reserves. To capture 25%, 50% and 75% of total habitat value for the owl required 14.0%, 29.2%, and 47.3% of the planning units, respectively; capturing the same for the fisher required only 5.3%, 13.5%, and 27.2%. A combined owl-fisher scenario resulted in areas that overlapped only ∼50% of existing reserves. The current location of LSRs may not be the best solution to maintaining well-connected habitats for these area-limited species in northwestern California. Whether LSRs are a better solution to protecting the diversity of other lesser-known taxa (i.e., salamanders and mollusks) is the subject of related work.     

Modeling of arsenic immobilization by zero valent iron

Ground waters in geothermal regions contain arsenic concentrations that exceed the recommended drinking water standards. In addition, when these regions have agricultural activities, the waters also contain high levels of nitrates and phosphates. These contaminants can be removed from the water with the use of filters containing zero valent iron (ZVI). The objective of this study was to model the removal of arsenate (As(V)) and arsenite (As(III)) by ZVI and to model the effect of competing ions (phosphate and nitrate) on arsenate removal. Arsenic immobilization by ZVI columns was simulated by the HM-1D chemical transport and speciation model and an one-dimensional analytical solution model. Laboratory column studies were conducted in order to obtain representative experimental data for simulation with both models. Arsenic speciation and the presence of competing ions greatly affect arsenic removal by ZVI. Most arsenic is precipitated/co-precipitated on ZVI and on the corrosion products formed on ZVI. The simulations suggested that As(V) process parameters are higher than the As(III) parameters and that they are affected by the presence of nitrates and phosphates in the system. Such models can be used to design treatment units by incorporating the impact of nitrates and phosphates in the removal of arsenic by ZVI as well as the impact of temperature on the process.     

汽车动力总成液压悬置建模与仿真研究

介绍功率键合图在动态系统特性分析中的特点和优势,以此为理论基础建立汽车动力总成液压悬置的数学模型,并结合MATLAB进行仿真,为液压悬置的研究提供了一种高效的建模仿真方法。应用这种方法,可以在液阻悬置的设计开发阶段较精确地预测产品的性能和进行优化设计,有利于提高产品设计质量、缩短开发周期。     

不同贮藏条件下小麦和玉米种子的水分变化规律及其建模验证

种子平衡水分(EMC)是评价种子吸湿或解吸动态变化的重要指标。本研究以不同初始水分(IMC)小麦和玉米种子为试材,研究了不同贮藏条件下的吸湿解吸规律,并建模验证。结果表明,玉米种子在8.0%IMC、15℃、相对湿度(RH)<18.8%, 25°C或40℃和RH<48.1%条件下; 以及在13.5%IMC或18.0%IMC、15°C、25°C或40℃、RH<48.1%条件下呈解吸变化; 而在其他条件下均呈吸湿变化。小麦种子在贮温15、25和40℃时,8.0%IMC在RH≤18.8%、18.0%IMC在RH≤48.1%时解吸,其他条件下吸湿; 13.5%IMC在15℃和RH<48.1%以及25、40℃和RH<18.8%时解吸,其他条件下吸湿。小麦种子在15℃和RH=53.0%、25℃和RH=48.0%以及40℃和RH=43.0%时的安全水分(SWC)依次为13%、11%和9%; 玉米种子在15℃和RH=55.0%、25℃和RH=50.0%以及40℃和RH=40.0%时,其SWC依次为14%、12%和9%。小麦种子EMC在15℃和RH>50.0%、25℃和RH>50.0%、40℃和RH>48.0%时超过其对应条件下的SWC; 玉米种子EMC在15℃和RH>50.0%、25℃和RH>47.0%以及40℃和RH>47.0%时超过其对应条件下的SWC。玉米郑单958的平衡时间(d)与IMC(x)、RH(y)和温度(z)的预测模型为d = 35.34 + 4.32x - 0.28y - 0.35z - 0.031xy - 0.012xz - 0.0011yz + 0.003y²,农大108为d = 39.76 + 2.35x - 0.39y - 0.27z - 0.022xy - 0.014xz - 0.0057yz + 0.008y²,小麦山农15为d = 25.69 + 7.65x - 0.27y - 0.89z - 0.12xy - 0.07xz - 0.007yz + 0.006y²+ 0.04z²,泰农18为d = 46.67 + 0.39x - 0.28y - 1.72z - 0.006yz + 0.006y²+ 0.017z²。模型经验证,预测性良好。     

基于UML模型的图书资料管理系统的设计与实现

以阿克苏地委党校图书资料管理系统的设计与实现为例，讨论了统一建模语言UML的特征及其在信息系统开发过程中的应用．文中主要描述了用例图、类图等UML的主要组成。     

基于双向DC/DC变换器的无刷直流电机调速系统仿真

在分析电动汽车电源系统和无刷直流电机数学模型的基础上,提出一种基于双向DC/DC变换器的无刷直流电机调速系统。阐述了该系统中隔离型双向全桥DC/DC变换器工作原理,并利用Simulink和电气系统模块库相结合,采用模块化的方法,对该调速系统进行了建模和仿真。仿真结果表明,该系统具有良好的调速性能。     

Rhizobium and phosphorus influence on lentil seed protein and lipid

Root nodulation by rhizobial bacteria and P fertilization may affect seed protein and lipid composition in plants by altering nitrogen (N) and phosphorus (P) nutrition or by eliciting metabolic responses by the host plant. This study was conducted to determine the effects of rhizobium and P fertilization on seed protein and lipid contents and yield of lentil (Lens culinaris Medik). Lentil was grown to maturity in a greenhouse with P levels of 0 (low) and 50 (high) mg kg^‐1 soil with or without inoculation with Rhizobium bacteria. At the low level of P, protein and lipid concentrations and protein contents were significantly higher in inoculated than in uninoculated plants. Seed dry weight and protein concentrations and contents were higher in inoculated than in uninoculated plants at the high level of P. Seed protein/lipid (Pro/L) concentration ratios varied between inoculated and uninoculated plants at both P levels, and was related to the intensity of root nodulation. Lipid and protein contents were highly correlated with P content in lentil seeds. Seed lipid and protein contents were lower at the high level of P in uninoculated than inoculated plants. The data indicate different patterns of seed P accumulation and different relationships between seed P content and protein and lipid contents in inoculated and uninoculated plants. This might indicate that the intensity of nodulation altered the response of seed protein and lipid metabolism to increasing P availability, which affected protein and lipid ratios.     

Modeling Osmotic Salinity Effects on Yield Characteristics of Substrate-Grown Greenhouse Crops

Abstract

In a series of experiments with different osmotic potentials in the root environment, various vegetables, and ornamentals were grown in a substrate system. The osmotic potential was varied by addition of nutrients. Yield characteristics of the crop were related to the osmotic potential of the nutrient solution. Experimental results were fitted to a discontinuous piecewise linear response model introduced by Maas and Hoffman in 1977 and this study extended the investigation by introducing a polynomial and an exponential test model. The correlation coefficients for the polynomial and exponential model were generally higher than with the piecewise linear model. The polynomial model has the drawback that calculation of the salinity yield decrease (SYD) value is not possible. Salinity threshold values could be calculated with all models tested. The average values did not show great differences and the EC values found were 2.4, 2.1, and 2.2 dS m^?1 for the polynomial, exponential, and peace wise linear model, respectively. It is argued that the exponential equations showed the closest relationships between the EC in the root environment and the yield characteristics of the crops. Fifth order polynomial equations yielded at least equal or even higher correlation coefficients, but these equations are very responsive to accidental positions of observations. The traditional discontinuous linear fitting gave reasonable results, but only when experimental observations below the threshold value were selected and discarded. This undermines the power of this model, because exclusion of observations is always arbitrary. Furthermore, a discontinuous relationship between crop yield and EC in the root environment is not likely, because yield response is of biological nature. Nevertheless, when the number of observations is not sufficient for the quantification of the exponential equation, mostly reasonable estimations of the salinity parameters can be obtained with the Maas and Hoffman model.     

基于Maplesim挖掘机机构建模与仿真分析

农业问题是当今中国面临的最大问题,而挖掘机是当代农用机械中必不可少的农用机械之一.该文利用Maplesim软件建立一种农用挖掘机工作机构仿真模型,然后对该机构模型进行运动学仿真分析,从而得到该机构的运动规律,机构节点的位移,速度,加速度情况下随时间的变化规律,为以后结构尺寸的设计和优化设计提供了一种可行的方法.这也使得设计人员在制造物理样机之前,对挖掘机的性能、运动状况等情况有了直观的了解,从而提高了设计效率和产品质量,降低了设计的成本.     

论我国南北方家具设计中的文化元素差异

我国南北方的文化地缘差异较为明显,因此其文化基础在环境因素、人文因素方面也存在着一定的差异性。基于此,与民众日常生活息息相关的家具设计与应用也存在着一些较为明显的不同。简述了我国家具文化的形态,分析了南北家具设计文化元素差异,在此基础上,探讨了新时代南北家具设计理念融合的思路。