Identification of a spatially efficient portfolio of priority conservation sites in marine and estuarine areas of Florida

• 1. A systematic conservation planning approach using benthic habitat and imperilled species data along with the site prioritization algorithm, MARXAN, was used to identify a spatially efficient portfolio of marine and estuarine sites around Florida with high biodiversity value.
• 2. Ensuring the persistence of an adequate geographic representation of conservation targets in a particular area is a key goal of conservation. In this context, development and testing of different approaches to spatially‐explicit marine conservation planning remains an important priority.
• 3. This detailed case study serves as a test of existing approaches while also demonstrating some novel ways in which current methods can be tailored to fit the complexities of marine planning.
• 4. The paper reports on investigations of the influence of varying several algorithm inputs on resulting portfolio scenarios including the conservation targets (species observations, habitat distribution, etc.) included, conservation target goals, and socio‐economic factors.
• 5. This study concluded that engaging stakeholders in the development of a site prioritization framework is a valuable strategy for identifying broadly accepted selection criteria; universal target representation approaches are more expedient to use as algorithm inputs, but may fall short in capturing the impact of historic exploitation patterns for some conservation targets; socio‐economic factors are best considered subsequent to the identification of priority conservation sites when biodiversity value is the primary driver of site selection; and the influence of surrogate targets on portfolio selection should be thoroughly investigated to ensure unintended effects are avoided.
• 6. The priority sites identified in this analysis can be used to guide allocation of limited conservation and management resources.

Copyright © 2008 John Wiley & Sons, Ltd.     

基于知识的变速箱齿轮虚拟设计研究

【目的】为解决农机变速箱虚拟设计与仿真过程中,齿轮零件复杂多变、知识重用率低的问题。【方法】在对变速箱齿轮知识进行分类的基础上,采用本体对齿轮设计知识进行描述,融合知识工程与参数化设计技术,提出了一种基于知识的齿轮虚拟设计方法。以拖拉机变速箱复杂花键齿轮设计为例对系统进行验证。【结果】以三维建模软件NX为平台开发了变速箱齿轮虚拟设计系统,通过人机系统界面获取齿轮设计需求,在齿轮设计知识库和模型库的支持下,利用知识重用推理出齿轮结构,在几何参数的驱动下,快速构建出符合设计需求的齿轮模型,实现了复杂结构齿轮的快速智能设计。验证结果表明,在人机界面进行设计需求录入,系统在数秒内自动输出花键齿轮详细结构模型。【结论】该系统可以较好地支持变速箱的虚拟设计与仿真,缩短了农机的开发周期,也可为其他机械产品的虚拟设计提供技术借鉴。     

基于压缩感知SAMP算法的改进

压缩感知是近年来兴起的以较大压缩比率并且能够以较好的效果恢复原始信号的一种新型理论。本文针对SAMP算法在重构精度相对较差以及运算时间较长的问题,提出一种新的SAMP改进算法。该算法首先将稀疏信号进行分块后再重构,其次在重构算法过程中开始对信号稀疏度进行初始估计,然后采取变步长增加稀疏度的方法逐步求出原始信号的最优估计值。理论分析和实验表明,改进后的算法减少运算时间,提高重构精度,增进实际使用价值。     

基于本体的故障诊断知识管理系统研究

针对目前企业内存在的故障诊断信息分散,不易共享和重用的问题,提出基于本体的故障诊断知识管理系统模型.根据故障诊断所涉及的源知识特点,建立了结构域、测试域和故障域3个异构领域本体模型,并根据各本体之间的连接关系给出了故障树生成算法,实现知识之间的共享和重用.以4L-20/8型两级空气压缩机为研究对象,开发了基于本体的故障诊断知识管理系统,该系统能为企业用户提供更精确的知识检索和诊断决策服务,为进一步的设备智能维护提供了条件.     

贵州不同产地烟叶油分的表征物质及化学成分含量

为探明贵州不同产地烟叶质量的风格特征,采取田间试验比较了贵州不同产地各部位烟叶油分的表征化学物质和常规化学成分含量差异。结果表明：1）贵州不同产地烟叶油分的表征化学物质总量为上部烟叶358．11～506．5μg/g、中部烟叶288．28～512．98μg/g、下部烟叶289．57～363．78μg/g,变异系数为7．4％～26．4％。其中,上部烟叶以都匀点最高,达506．50μg/g;正安点最低,为358．11μg/g。中部烟叶以正安点最高,达512．98μg/g;贵定点最低,为288．28μg/g。下部烟叶以贵定点最高,达363．78μg/g;都匀点最低,为289．57μg/g。从烟叶产区看,上部烟叶油分的表征化学物质总量为黔南烟区高于黔北烟区,平均高25．5％,中、下部烟叶油分的表征物质总量不同产区的变化规律不同。2）中、下部烟叶的总糖和还原糖含量均为黔北烟区高于黔南烟区,总糖含量分别高51．9％和109．9％,还原糖含量分别高40．8％和95．6％;总氮含量则是黔南烟区高于黔北烟区,分别高21．2％和25．3％。上部烟叶的总糖和还原糖含量为黔南烟区高于黔北烟区,分别高76．5％和84．2％。     

翻译中的理解与表达

翻译是把一种语言表达的思想用另一种语言重新表达出来的活动。翻译过程是一种艺术的再创造过程。它包含有理解与表达两个基本环节。理解是表达的基础 ,表达是理解的表现形式。本文从理解语言现象、了解背景知识、分析逻辑关系及具体语境等四个方面探讨正确理解原文对确切表达的重要性 ,并提出相应的表达时应注意的问题及对策     

新疆环塔里木稀植果林间套种牧草生产初步研究

研究了南疆环塔里木特色林果产区果林行间套种生产牧草的干草产量、根系分布、营养品质及土壤相关性状,探讨林下套种牧草的生产可行性及对果园土壤的影响.结果表明:高大成龄香梨果林套种高羊茅、鸭茅、黑麦草和苏丹草干草产量分别为5.45、3.62、4.71、11.12 t/hm2;低矮红枣果林行间套种草木樨、大叶苜蓿、苏丹草、一年生黑麦草一年内可刈割3次,其干草产量分别达到9.20、8.78、14.33、7.58 t/hm2,且供试牧草地下根量的90％以上都集中在20 cm土层以内,果园生草后土壤有机质和氮磷钾含量均高于清耕区;稀植果林套种牧草可以保证一定的牧草产量和品质,对果林根层土壤性状无明显负面影响.     

Application of supernodal sparse factorization and inversion to the estimation of (co)variance components by residual maximum likelihood

We demonstrated that supernodal techniques were more efficient than traditional methods for factorization and inversion of a coefficient matrix of mixed model equations (MME), which are often required in residual maximum likelihood (REML). Supernodal left‐looking and inverse multifrontal algorithms were employed for sparse factorization and inversion, respectively. The approximate minimum degree or multilevel nested dissection was used for ordering. A new computer package, Yet Another MME Solver (yams ), was developed and compared with fspak with respect to computing time and size of temporary memory for 13 test matrices. The matrices were produced by fitting animal models to dairy data and by using simulations from sire, sire–maternal grand sire, maternal and dominance models for phenotypic data and animal model for genomic data. The order of matrices ranged from 32 840 to 1 048 872. The yams software factorized and inverted the matrices up to 13 and 10 times faster than fspak , respectively, when an appropriate ordering strategy was applied. The yams package required at most 282 MB and 512 MB of temporary memory for factorization and inversion, respectively. Processing time per iteration in average information REML was reduced, using yams . The yams package is freely available on request by contacting the corresponding author.     

LP analysis in a tank irrigation system for near real representation and optimal allocation of area

There is a wide gap between an ideal situation and actual conditions existing in the field of irrigation management in any tank irrigation system in India. To bridge this gap, a near real time analysis through LP modeling of the existing situation and the best allocation policy is attempted for the Aralikottai tank system. The actual conditions are simulated at each sluice command level whereas the best operational policy is attempted for the entire system as a whole. The analysis is conducted separately for a drought year (1988) and a surplus year (1990) with the available five year data from 1988 to 1992. The major conclusions indicate that the late transplantations of the rice crop and the excess water application during the periods of water availability (leading to water stress during the last stages of crop maturity) are the causes of the meagre benefits in a drought year. Also, in a surplus year the excess water application over the entire cropping season resulted in under utilization of land resources and moderate benefits. The existing status of irrigation can be improved to obtain the maximum benefits from the tank command area based on the quantification done.     

黑果枸杞在格尔木地区不同土壤中造林试验

采用三种苗木（容器苗、移植苗和裸根苗）在格尔木地区三种不同的土壤类型（农耕地、撂荒地和稀疏林地）中进行了栽植试验,结果表明,苗高、地径和冠幅的增长量与土壤类型、苗木类型之间具有明显的关联性,相关系数为R（苗高）=0.910（R2=0.828）、R（地径年增长量）=0.903（R2=0.815）和R（冠幅年增长量）=0.909（R2=0.736）;苗高、地径和冠幅的增长量依土壤类型从大到小的排序为：农耕地〉撂荒地〉稀疏林地;依苗木类型从在到小的排序为：容器苗〉移植苗〉裸根苗;在格尔木地区土壤条件较差的撂荒地和稀疏林地,采用容器苗和移植苗栽植黑果枸杞,采用容器苗和移植苗可使造林成活率提高19.4～36.6个百分点,且苗木生长良好,可有效提高土地利用率。