三峡水库成库期间鱼类空间分布的水声学研究

２００７年４月１８日～５月１日,利用ＳＩＭＲＡＤＥＹ６０回声探测仪（又称鱼探仪）对三峡水库坝前到丰都干流以及９条主要支流进行了水声学探测。采用垂直探测结合“之”字形路线的方法对库区整个水体鱼类的分布状况进行了研究。调查水域长度约有６００ｋｍ,回波数据分成１２３２个片段进行分析。结果表明：在５ｍ以下水层,体长大于６ｃｍ的鱼类在该区域平均密度为５６７．６８尾／ｄａｍ３,且鱼类分布不均匀。在巫山至奉节江段鱼类的密度最低, 密度的平均值和标准误（ｍｅａｎ±Ｓ．Ｅ）为（８．１±０．４７）尾／ｄａｍ３;在忠县到丰都江段密度最高,平均值和标准误（ｍｅａｎ±Ｓ．Ｅ）为（２５９７．０６±１５４．０８）尾／ｄａｍ３。从坝前到丰都,干流鱼类资源量总体上呈现逐步增加的趋势。支流资源量要比干流高。目标强度在－６０～－５０ｄＢ的鱼体大小差异不显著,大于－５０ｄＢ鱼体的平均目标强度在巴东－巫山江段最高,巫山－奉节江段及抱龙河次之。小型鱼体的大小在各江段没有统计学差异,中型和大型鱼体在巴东－巫山江段鱼体个体相对最大,万州－忠县江段以及小江、长滩河等水域鱼类个体相对较小。     

Predicting the Stiffness of Sawn Products by X-ray Scanning of Norway Spruce Saw Logs

The aim of the study was to investigate the possibility of strength grading Norway spruce [Picea abies (L.) Karst.] saw logs on the basis of simulated X-ray LogScanner measurements and to evaluate the potential accuracy of X-ray LogScanner measurements of green heartwood density and percentage of heartwood. The study was based on 272 logs for strength grading and 29 logs for measurements of green heartwood density and percentage of heartwood. The logs were scanned using computed tomography (CT). After sawing, the modulus of elasticity (MOE) of the centre boards was measured using a strength-grading machine. The CT images were used for simulations of an X-ray LogScanner, resulting in simulated measurements of different variables such as diameter, taper, percentage of heartwood, density and density variations. Multivariate models for prediction of MOE were then calibrated using partial least squares (PLS) regression. The MOE of a log was defined as the mean value of the MOE of the two centre boards. The study showed that the simulated X-ray LogScanner measured the percentage of heartwood and green heartwood density with relatively high accuracy (R ² = 0.94 and R ² = 0.73, respectively, after removing two outliers) and that these and other variables measured by the simulated X-ray LogScanner could be used to predict the stiffness of the centre boards. These predictions were used to sort the logs according to the predicted MOE. When sorting out 50% of the logs (''high-strength'' logs), the percentage of C30 boards increased from 73% (all logs in the study) to 100% (only ''high-strength'' logs). The rest of the logs could then be divided into two groups, one of them with 100% C24 and C30 boards.     

辽东山区落叶松大径材林抚育间伐研究

对落叶松大径材人工林抚育间伐进行实地调查研究,确定了正确的抚育间伐时间、间隔期、强度和方法,并对抚育间伐产生的经济效益进行了分析。     

ZS1105型柴油机机体改进设计

应用PRO/E三维造型软件和ANSYS有限元分析软件,建立了ZS1105柴油机机体的有限元模型,并对其进行结构强度的分析,找出应力集中的危险截面,得到了最佳设计方案,为该机体的改进设计提供了依据。     

油缸未焊接部位强度近似设计式的确定

为确立一种对复杂形状裂纹体强度设计式的推导方法，利用正交法确定了解析条件，以回归式的形式得出了设计式。运用此方法和数次数值解析，获得了有足够精度的油缸底盖与缸体间未焊接部位的强度设计式。     

链条联结牢固度对疲劳性能的影响

通过大量试验，分析研究了链条的联结牢固度对疲劳性能的影响，找出了它们之间的相互关系，并得出了二者相互关系曲线，结果表明提高联结牢固度能够提高疲劳强度。同时验证了内、外链节联结牢固度对疲劳性能的影响是相同的。     

林区某工程本体取样检验C50混凝土强度的折算分析

针对本体取样法在检验结构混凝土强度的应用,采用了误差理论对取样强度值进行数据处理.由此计算修正系数和回归分析,探寻本体取样与标养试件混凝土强度之间的折算关系,并对两种修正结果进行了比较分析,得出回归方程更精确的结论.     

用禽流感H9SD株适时强免对提高蛋鸡生产性能的影响

为了防控低致病性禽流感引发的产蛋下降症,在用禽流感H9HL株免疫(对照组)的同时,再用H9SD696株强化免疫2次(试验组)。结果显示,不同时期抗体效价试验组比对照组平均高出0.66个滴度;平均周产蛋率高出1.25%;死淘率降低2.78%,生产性能和经济效益显著提高。用不同毒株的疫苗免疫鸡群在防控低致病性禽流感的实践中能发挥协同防患的作用,具有一定推广价值。     

不同浓度营养液对油麦菜生长的影响

以油麦菜为试验材料,设计3种日本园试营养液配方浓度,研究其对油麦菜无土栽培生长及产量的影响.研究结果表明,在园试标准营养液配方1/8～1,2浓度范围内,随着营养液浓度的提高,油麦菜各植株鲜质量、小区产量及植株的叶长、株高、叶数、株干质量、根干质量均有不同程度的增加,其中园试标准营养液配方1,2浓度处理最高.     

水泵涡壳强度校核程序设计

水泵关键零件的强度计算与校核直接关系着整机的性能、使用寿命及可靠性,传统的水泵零件强度校核方法在精度、效率等方面已远远满足不了生产要求.在探讨涡壳强度校核理论的基础上,建立了涡壳强度校核应用程序的校核模型,并对该应用程序的开发平台、开发工具、关键技术以及具体实现方式进行了阐述和分析.实例验证的结果表明效果良好,具有较好的推广应用前景.