农用车变截面板簧变值轧制成形技术

变截面板簧是农用车辆悬挂系统中的一种新型弹性元件。提出了变值轧制的概念和工艺方法,研究了变值轧制成形工艺的基本原理、辊缝与轧件长度关系、咬入条件、金属的滑动、宽展控制方法、轧透条件等关键问题。给出了变截面板簧仿形变值轧制成形和电液伺服变值轧制成形方法的原理。     

农用车少片等长变截面钢板弹簧优化设计分析软件

介绍了等长少片变截面钢板弹簧优化设计软件,对企业有一定的指导意义。     

钢板弹簧的用与修

钢板弹簧是机动车车桥与车架 (或车厢 )之间的弹性连接件，它缓冲并吸收了车辆运行中的冲击和振动能量，是重要的减震装置。它的技术状态好坏，直接影响车辆行驶的平稳性，必须正确使 用与维修。 钢板的正确使用 　　(1)严格按规定要求装载，不得超载或偏载。因为钢板弹簧是按机动车辆的额定载重量设计的，超载后将使钢板弹簧在工作中产生较大的弯曲应力，易疲劳变软或折断。 　　(2)车辆如需停歇较长时间，而车厢里的重货一时不能卸下时，应用其它硬物将车厢支起，防止钢板长时间受重压造成强度降低而损环。 　　(3)在不平的路面上行驶时…     

钢板弹簧的用与修

钢板弹簧是机动车车桥与车架(或车厢)之间的弹性连接件,它缓冲并吸收车辆运行中的冲击和振动能量,是重要的减震装置。它的技术状态好坏,直接影响车辆行驶的平稳性,因此,必须正确使用与维修。     

钢板弹簧的用与修

钢板弹簧是机动车车桥与车架(或车厢)之间的弹性连接件,它缓冲并吸收了车辆运行中的冲击和振动能量,是重要的减震装置.它的技术状态好坏,直接影响车辆行驶的平稳性,必须正确使用与维修.     

用等效刚度法计算变截面梁的变形

按照变截面梁与等截面梁弯曲应变能等效的原则，求出变截面梁的等效刚度，然后采用等截面梁的计算公式来计算变截面梁的变形。     

用等效刚度法计算变截面梁的变形

按照变截面梁与等截面粱弯曲应变能等效的原则，求出变截面梁的等效刚度，然后采用等截面梁的计算公式来计算变截面梁的变形。     

钢板弹簧的热处理工艺控制

对汽车钢板弹簧生产中出现的问题进行分析,阐述了热处理设备的操作对钢板弹簧质量的影响,可对生 产起指导作用。     

农用运输车钢板弹簧的维修

钢板弹簧是农用运输车后桥与车架或与车厢之间的弹性连接件。钢板弹簧可缓冲并吸收车辆运行中的冲击振动能量，是重要的减振装置。它技术状态的好坏，直接影响车辆行驶的平稳性。钢板弹簧经长期使用后，会出现弹性减弱或折断等现象，必须及时修复或更换。１．钢板弹性减弱后的修复钢板弹簧弹性减弱，外观上表现为拱度减小。因此，一般只要检查钢板弹簧的拱度（钢板弹簧两端销孔中心线与第１片的距离），即可判断其弹性强弱。钢板弹簧的拱度可通过拉线用直尺测量，也可用新钢板弹簧片进行靠合检查。要求同一轮轴上左右两侧板簧总成片数相等，…     

补灌量和覆盖量耦合变化下旱地春小麦叶面积指数对产量的影响

[目的]免耕覆盖中补灌量和秸秆覆盖量耦合变化下春小麦叶面积指数对产量有较大影响。[方法]本研究以甘肃省定西市安定区1979—2019年历史气象数据为基础，运用APSIM模型对补灌量与覆盖量耦合变化时旱地春小麦的叶面积指数和产量及其构成因素进行模拟，并采用DPS软件进行分析实验，研究补灌量和覆盖量耦合下旱地春小麦叶面积指数对产量的影响机制。[结果]结果表明：在试验设计范围内, 不同春小麦叶面积指数对春小麦千粒质量的影响效应在开花-灌浆期为向上的二次抛物线变化。其他时期，不同春小麦叶面积指数对春小麦产量和千粒质量的影响效应为向下的二次抛物线变化, 不同春小麦叶面积指数对春小麦籽粒数的影响效应为向上的二次抛物线变化。试验变化范围内，各个时期春小麦千粒质量均未出现阈值，分蘖—拔节期，春小麦产量未出现阈值，春小麦籽粒数出现阈值，春小麦叶面积指数为1.72时春小麦籽粒数出现最小值为8716.59/m2 。其他时期，春小麦产量和籽粒数出现阈值，在春小麦叶面积指数为0.94，2.31，1.67，1.18，1.24，0.79时春小麦产量出现最大值为3818.71kg/hm2，3827.06kg/hm2，3851.41kg/hm2，3904.35kg/hm2，3819.03kg/hm2，3853.72kg/hm2。春小麦叶面积指数为0.77，2.01，1.44，1.07，1.00，0.70时春小麦籽粒数出现最小值为9579.34/m2，8745.26/m2，9638.01/m2，9050.71/m2，8554.04/m2，9038.38/m2。春小麦叶面积指数对产量和千粒质量呈正效应，对籽粒数呈负效应。[结论]合理调节春小麦叶面积指数，可以促进透光性速率的提高、光合产物的产生，对春小麦产量的提高具有积极的意义。     

营养液供液量与供液频率对冬春茬辣椒的影响

为了了解营养液不同供液量和供液频率对辣椒生长发育、果实品质和水分利用效率的影响,以“洋大帅”为试验材料,采用基质槽培的栽培方式进行试验.试验设置了3个不同供液量(在苗期,每株辣椒每天的供液量分别为W1:300 mL,W2:400 mL,W3:500 mL,开花坐果期每株辣椒每天的供液量加倍,结果期每天的供液量是苗期的3倍)和3个不同供液频率(整个生育期,每天的供液频率维持不变,即T1:2次/d,T2:3次/d,T3:4次/d).结果表明:当供液量为W2时,地上部分与地下部分相关性最好;处理W1T2水分利用效率最高,为18.13 kg/m³,但是其产量最低;处理W3T1的总根表面积最大,为754.54 cm³;处理W3T2辣椒生长最好,有最大的株高和茎粗,果实品质与水分利用效率也相对较好.因此,处理W3T2为试验条件下基质培冬春茬辣椒最佳的供液量和供液频率.     

Effects of frequency of irrigation and gypsum treatment on leaf water potential and leaf stomatal conductance of lucerne (Medicago sativa L.) grown on a heavy clay soil

Summary Concurrent diurnal measurements of water potential, osmotic potential and conductance were made on leaves of lucerne grown under weekly (W) and fortnightly (F) irrigation on gypsum-treated (G) and untreated soil (C). Measurements were made throughout the period of vegetative growth.Leaf water potentials were lower both at dawn and in the afternoon under fortnightly as compared to weekly irrigation. Gypsum application led to a slower decline in water potential under fortnightly irrigation, although the effect was small compared with more frequent irrigation. Stomatal conductance was reduced under treatments F_G and F_C during the later stages of vegetative growth, coinciding with leaf water potentials of less than c. –1.6 MPa.The relationship between leaf water potential and turgor potential changed with time such that positive turgor was maintained as leaf water potential declined. Turgor maintenance was achieved through a decrease in leaf osmotic potential. These data suggest that lucerne is capable of osmotic adjustment.Stomatal conductance declined rapidly below a leaf turgor potential of c. 0.1 MPa. It is hypothesised that osmotic adjustment enabled stomatal adjustment, which contributed to continued assimilation despite increasing soil moisture deficits.     

Water and salt transport,water uptake,and leaf water potentials during regular and suspended high frequency irrigation of citrus

High frequency irrigation of citrus was interrupted for up to 2 months to study the dynamics of salt and water transport in soil, water uptake distributions and leaf water potentials. Irrigation water was applied to less than half the surface area per tree. Water content profiles and chloride distributions indicated that of the water uptake below the irrigated area, about 80% took place above 0.60-m depth, and that considerable water was taken up from outside the irrigated area. The water for the latter was supplied by lateral flow, as evidenced by the hydraulic gradients, the relative extent of the lateral flow in summer and winter, and the fact that at 0.90-m depth water contents were uniform. In summer, the citrus showed signs of stress after about 4 weeks of suspended irrigation. At that time leaf water potentials did not recover any longer during the night. This study indicates that high frequency irrigation of citrus is not too vulnerable to temporary system breakdown and that deficit-irrigation could be practiced.     

贵州特色烟叶开发措施的探讨

针对贵州特色优质烟叶开发过程中存在的问题,提出了从科学合理规划入手,加强基地基础设施建设,完善组织形式,加强透明管理出发,完善单元基地建设.从加大自育品种推广,提高养分利用效率,优化烟株田间群体结构,提高烟叶成熟度和上部烟叶可用性完善烟叶生产技术体系.     

Determining the optimal size of water users' associations

In 1985 the General Irrigation Department (DGI) of the Province of Mendoza, Argentina, launched a water users' associations reorganization program to attain administratively more effective associations. At that time there were 760 water users' associations (WUAs) managing a total irrigated area of 360,000 ha. Under the reorganization program all water users' associations of less than 1000 ha were merged into larger organizations. The main obstacle to the viability of small WUAs was the lack of adequate funding to perform their irrigation water management responsibilities. At that time it was thought that the ideal administrative area should range from 10,000 to 15,000 ha. Eight years after the reorganization, the total number of WUAs was reduced to 360. This paper reviews the experience with the reorganization program. It concludes that the optimal size should be between 3000 and 10,000 ha to minimize management costs. This conclusion is based on the detailed budgets of nine new WUAs administering from 500 to 14,000 ha.     

一种判定喷油嘴内部金属类杂质堵塞物来源的方法

针对油嘴内部金属类杂质堵塞物,通过金相组织的比对分析,借此判定其堵塞物的来源。该方法简单快捷、易操作,且采用常规仪器就能实施检测判定,具有可推广的实用价值。     

基于Matlab的圆柱螺旋弹簧优化设计

按照机车车辆圆柱螺旋弹簧传统设计思路,建立了圆柱螺旋弹簧优化设计模型,并采用Matlab优化模块进行了实例分析,表明所建优化模型是合理的。     

导轴承刚度对水轮机轴系自振特性的影响

为研究水轮发电机组轴系横向自振特性,采用有限元方法对轴系进行离散,利用能量法获得运动方程,根据简化的实际机组轴系参数,采用Matlab软件计算机组轴系各阶的固有频率、主振型以及临界转速,分析导轴承刚度系数的变化对机组轴系临界转速和主振型的影响．计算结果表明:当仅改变其中1个导轴承刚度时,上导轴承对机组临界转速几乎没有影响,下导和水导轴承对临界转速的影响较大．当导轴承刚度达到一定值时,临界转速不再随其增大而增大,出现“饱和”现象;而同时增加3个导轴承的刚度,机组轴系的临界转速有较大的增大．上导轴承的改变对前三阶振型几乎没有影响,下导和水导轴承的改变会导致某一阶的振型与原振型相反．工程中估算机组临界转速时需充分考虑导轴承刚度对机组的影响．     

Water use of spring wheat to raise water productivity

In semi-arid environments with a shortage of water resources and a risk of overexplotation of water supplies, spring wheat (Triticum aestivum L.) is a crop that can reduce water use and increase water productivity, because it takes advantage of spring rainfall and is harvested before the evaporative demands of summer. We carried out an experiment in 2003 at “Las Tiesas” farm, located between Barrax and Albacete (Central Spain), to improve accuracy in the estimation of wheat evapotranspiration (ETc) by using a weighing lysimeter. The measured seasonal ETc averages (5.63 mm day⁻¹) measured in the lysimeter was 417 mm compared to the calculated ETc values (5.31 mm day⁻¹) calculated with the standard FAO methodology of 393 mm. The evapotranspiration crop coefficient (Kc) derived from lysimetric measurements was Kc-mid: 1.20 and Kc-end: 0.15. The daily lysimeter Kc values were fit to the evolution linearly related to the green cover fraction (fc), which follows the crop development pattern. Seasonal soil evaporation was estimated as 135 mm and the basal crop coefficient approach was calculated in this study, Kcb which separates crop transpiration from soil evaporation (evaporation coefficient, Ke) was calculated and related to the green cover fraction (fc) and the Normalized Difference Vegetation Index (NDVI) obtained by field radiometry in case of wheat. The results obtained by this research will permit the reduction of water use and improvement of water productivity for wheat, which is of vital importance in areas of limited water resources.