等螺旋角圆锥压缩螺簧的计算方法

在建立基本方程的前提下,给出了等螺旋角圆锥压缩螺旋弹簧的设计计算方法,其中包括载荷-变形特性、各圈压并载荷、各圈最大应力、各种相关参数,以及螺旋角和圆锥角的影响等。并给出了计算实例。     

甘蔗分段收获经济效益分析

介绍了由4GZ-9型甘蔗割铺机、6BZ-5型甘蔗剥叶机以及7TS-15型甘蔗装载机组成的最小甘蔗收获系统,并对该系统进行了应用效益分析。通过分析说明采用分段式甘蔗收获技术在经济上是可行的,在目前国情下宜以分段收获作为切入点,促进我国甘蔗收获逐步实现机械化作业。     

用随机发育模型预测马尾松毛虫的发生期

用马尾松毛虫各龄虫口密度的定期调查资料和积温资料,拟合Logistic随机发育模型,结果表明,该模型能精确地描述马尾松毛虫第1代1～6龄幼虫的发育进程。对各龄虫口的时间分布,模型预测值和观察值的吻合程度达90%。对模型参数进行比较表明,除了温度(积温)以外,还有另外一些因素影响着马尾松毛虫的发育进程。     

刚果12号桉W5无性系与尾叶桉U6无性系胶合板材立木

利用雷州林业局刚果12号桉W5无性系林分中胸径8～18 cm径阶，树高11～23 m的样木1 207株和尾叶桉U6无性系林分中胸径8～18 cm径阶，树高10～21 m的样木784株，按材种规格标准造材实测材积，且分别建立刚果12号桉W5无性系和尾叶桉U6无性系胶合板材立木出材量二元回归方程，经检验精度可靠，可供参考使用。     

甩挂运输车队运营组织模式分析

甩挂运输作为一种节能减排、低碳高效的运输方式,也是我国目前大力倡导推行的运输方式之一,甩挂运输不仅是发展低碳物流的手段,也是企业提高工作效率,获得更大的经济效益和社会效益的可行之举.在国家政策和行业发展的推动下,甩挂运输必将成为运输行业的发展趋势.本文对甩挂运输的工作原理进行介绍,并针对甩挂运输的车队运营组织模式进行分析,将其分为4大类.结合图像对每一类运营组织模式的特点进行研究,并通过实例分析,得出该类模式的适用情况.通过系统的比较和分析这4种不同的车队组织运营模式,从理论上为物流运输企业开展甩挂运输的车队运营组织模式选择提供决策依据.     

Soil water affects transpiration response to rainfall and vapor pressure deficit in poplar plantation

Influences of environmental factors on transpiration are interactive. Sensitivities of transpiration responses to both evaporative demand and rainfall under contrasting soil water conditions constitute the physiological basis of the drought tolerance of trees. Such knowledge is practically significant for plantation management, especially for irrigation management. We therefore conducted a 6-year study on the transpiration of a poplar plantation in temperate China to elucidate the existence and pattern of the influence of the soil water over stand transpiration responses to (1) vapor pressure deficit (VPD), the major indicator of air dryness and (2) the rainfall, in terms of total amount and event size. The results showed that the response of plantation transpiration (E _c ) to VPD was conditioned by soil moisture. There was a significant difference in the frequency distribution of maximum sap flux under contrasting soil relative extractable water. E _c after rainfall of different sizes varied under similar VPD. The increasing occurrences of only large rainfall events led to enhanced total E _c during the growing season, but prolonged rainless intervals did not lead to a continuous decrease of E _c , suggesting appreciable supplements from the soil water were present to sustain transpiration. In addition, the balance of soil water between replenishment and extraction also conditioned the influence of rainfall over subsequent E _c during the respective rainless intervals. Based on the E _c responses to VPD and rainfall under different soil moisture levels, irrigation that directly replenishes the deep soil layers in order to alleviate water stress on transpiration during the small-rain event-dominated growing season is an effective and water-saving approach to guarantee trees survival during drought period.     

Prediction of bending properties for structural glulam using optimized distributions of knot characteristics and laminar MOE

This study established a prediction model for bending properties of glued-laminated timber (glulam) using optimized knot and modulus of elasticity (MOE) distributions of lumber laminate as the main input variables. For this purpose, knot and MOE data were investigated for all pieces of lumber that were prepared for glulam manufacturing, and statistical distributions of knot size, knot number in one lumber, and MOE of each laminate were optimized as distribution functions. These knot and MOE data were used as input variables in the prediction model for bending properties, and were also used in generating virtual glulam using the inverse transform method. Prediction of bending properties for glulam was carried out using the transformed section method, which is partially provided in ASTM D 3737 (Annex A4). Predicted values were compared with those from full-scale four-point bending tests for 60 six-layered glulams with 10 different laminar combinations. Finally, the allowable bending properties of glulam for each specific laminate combination were determined by calculating the fifth percentile of the modulus of rupture and the average modulus of elasticity from virtual test results of more than 1000 virtual glulams. From the results of this study, predicted bending properties for glulam and their distributions could be used for structural design in both allowable stress design and limit state design.     

文心兰茎尖离体培养研究

文心兰茎尖培养的研究，试验结果表明：文心兰茎尖在MS BA2mg／L NAA0．5mg／L培养基上，离体培养1个月后产生原球茎．改良KC基本培养较适原球茎的增殖；用BAI．5mg／L NAA0．2mg／L的激素配比，原球茎月增殖宰可达332．5％；CW可以减少原球茎褐死现象和促进原球茎的增殖：壮苗阶段，以附加NAA0．5% 10％香蕉汁的效果较好．水苔是良好的移栽基质，成活率在85．3％．     

Early growth analysis and evaluation of 21 Eucalyptus clones in Leizhou Peninsula

The growth, morphology, and wind resistance of 21 Eucalyptus clones were investigated and analyzed in Leizhou Peninsula, Zhanjiang city. The results showed that coefficient of variation of each index phenotype varied from 15.21%-42.46%. There were significant differences among the clones in growth indexes. The top five clones with high individual volume were JJ144, 2#, 28#, 9#, and JJ197. The morphological indexes were significantly different among the clones. There were also significant differences among the clones in wind resistance index, and the clones with good wind resistance were 28#, JJ162, JJ195 and JJ215, their preservation rate were more than 80%. It was found that tree height and DBH significantly correlated to individual volume, and stem form was significantly related to branch. Using the principal component analysis, it was determined that JJ144, 2#, 28#, 9# and JJ162 were the excellent clones with good performance in the Leizhou area.     

尾叶桉等植物叶提取液对几种植物插条生根和种子萌发的影响

尾叶桉等植物叶提取液对几种植物插条生根和种子萌发的影响＊黄卓烈林韶湘谭绍满林松煜杨国清莫晓勇关键词尾叶桉落地生根紫竹梅水竹草插条生根种子萌发桉树是相当难生根的植物。当用桉树的成熟枝条扦插时成功率极低［１］，甚至成活率为零［２］。柳树和杨树则是较容易生...