热压温度及板材密度对竹木复合层积材顺纹抗压强度的影响     

张晓春  蒋身学  张齐生 《林业科技开发》2011,25(2):45-47

通过单因变量两因素重复试验,以毛竹竹篾和桦木单板为原料,使用酚醛树脂胶黏剂压制竹木复合层积材,分析热压温度及板材密度对竹木复合层积材顺纹抗压强度的影响。结果表明,在试验选定因素水平范围内,热压温度和板材密度对竹木复合层积材顺纹抗压强度影响显著,板材顺纹抗压强度随热压温度的升高而增强,但145℃与160℃两水平之间差异并不显著;不同密度对板材顺纹抗压强度的影响差异显著,板材的顺纹抗压强度随板材密度的增大而增大;在其他工艺参数相对不变的情况下,热压温度与板材密度的交互作用对板材顺纹抗压强度的影响并无显著的影响。  相似文献   

裁板锯偏转机构运动关系的反求设计与仿真   总被引：1，自引：1，他引：0  

程朋乐  谭月胜  许亚东 《林业机械与木工设备》2011,39(8)

针对裁板锯锯片偏转系统运动关系复杂不易于单片机编程的问题,提出了应用反求设计开发模式求出连杆与丝杠系统的伸长量X和与之对应锯片偏转角度θ之间的函数关系。从采用Lagrange插值仿真得到的系统仿真曲线可知,四次多项式传递函数可以满足运动关系的精度要求,采用Matlab仿真最终确定二者之间的关系为一次函数。通过实验得出当偏转角为10°和35°时计算得到的直线误差最小,据此设计的裁板锯MJ6130Z已经批量生产。

Abstract：

In view of the problem that complicated motion relationship of the blade deflection system of board cutting saws makes MPU programming difficult,the function relation between the extension volume of the connecting rod and screw rod system and the correspo  相似文献   

Influence of tillage practices and nutrient management on crack parameters in a Vertisol of central India   总被引：5，自引：0，他引：5  

K. K. Bandyopadhyay  M. Mohanty  D. K. Painuli  A. K. Misra  K. M. Hati  K. G. Mandal  P. K. Ghosh  R. S. Chaudhary  C. L. Acharya 《Soil & Tillage Research》2003,71(2):133-142

The frequency, size and rate of development of cracks influence the transport of water, nutrients and gases in the soil profile and plant growth processes in Vertisols. Despite their importance, studies on characterising cracks in Vertisols of India are limited. This study attempts to evaluate the influence of different tillage practices, nutrient management and cropping systems on cracking behaviour of a Vertisol in central India. The length, depth, width, area and volume of cracks were recorded after the harvest of the wet season crops, i.e. soybean (Glycine max L.) and rice (Oryza sativa L.) from three ongoing tillage experiments with three different cropping systems, i.e. soybean–wheat (Triticum aestivum L.), soybean–linseed (Linum usitatissimum L.) and rice–wheat. The results revealed that all the crack parameters were significantly negatively correlated with the water content of the 0–15 cm soil layer and, crack width and crack volume were significantly positively correlated with the bulk density of the 0–15 cm soil layer. Gravimetric water content and bulk density of the 0–15 cm soil layer together explained 79% variation in the crack volume. The crack volume was significantly negatively correlated (r=0.86,P=0.01) with the root length density of the previous soybean crop. Rice grown under puddled condition significantly enhanced different crack parameters viz., length, depth, width, surface area and volume of the cracks over nonpuddled direct seeded rice. Sub-soiling practised in soybean under the soybean–linseed system significantly reduced the width, depth, length and surface area of cracks by 12.5, 10, 5 and 12%, respectively, over conventional tillage. No tillage practised in soybean under soybean–wheat system resulted in significant increase in width, depth and volume of the cracks but decrease in length and surface area of cracks over conventional tillage and mould board tillage practice. Application of manure reduced the magnitude of different crack parameters in soybean–linseed cropping system. Thus cracking in Vertisols can be favourably managed by the selection of proper tillage practice, cropping system and organic manure amendments.  相似文献   

Analysis of embedded gas detection system based on nano-porphyrin arrays     

LUO Xiao gang  BAI Xing hong  HOU Chang jun  HUO Dan qun  FA Huan bao  YANG Mei 《保鲜与加工》2011,(12):48-53

In view of the necessity of gas detection in environment, an embedded gas detection system is designed based on the basic principles of chromatography change of chemical reaction between nano-porphyrin arrays and micro-gas, which takes ARM9 S3C2440A as the core and nano-porphyrin array as the sensors. The overall program, the circuit organization and control software of the main function module such as spectrum signal acquisition, processing and monitoring are presented. With energy conservation differential equation, the control model of temperature and flow rate in the sample chamber is established, which can precisely control the detection conditions of chemical sensors. Some typical trace gases such as ammonia, enanthaldehyde, cyclohexane and hexanal are tested by the system, and the results show that the system can achieve rapid and accurate detection of trace volatile gas.  相似文献   

独立董事制度质疑与公司监控机制的完善     

张纯  向景 《湖南农业大学学报(自然科学版)》2002,(3)

我国证券管理机构在上市公司中推行独立董事制度的意向 ,忽略了不同国家的法律文化、法律传统等方面的制度差异 ,也缺乏相应的配套制度。要从根本上改变我国上市公司监控失灵、法人治理水平落后的局面 ,必须优化监事会功能 ,进行监督制度的创新 ,实现监控模式由内部单边监控向内部和外部多边监控的转变。  相似文献   

渠道预制混凝土板配合比设计研究     

杨晶杰  孙兆雄  葛毅雄  努尔开力  于玲 《新疆农业大学学报》2002,25(2):66-69

在大量试验基础上，对预制板混凝土配合比进行研究。研究表明复合掺用引气剂和减永剂是提高混凝土耐久性的有效措施，使混凝土抗冻等级大于F200，抗渗等级大于W10。预制混凝土板宜采用较高砂率，试验采用36％的砂率，使混凝土板质量得到保证。  相似文献   

新型OSB拌胶机工作参数对OSB力学性能的影响     

谢敏芳  谢拥群  林铭  魏起华 《福建林学院学报》2007,27(3):240-243

研究新型定向刨花板拌胶机的不同工作参数对拌胶刨花压制成的OSB板子性能的影响,试验结果表明:拌胶机滚筒的装载量以刨花占滚筒容积15%为宜,最佳转速为13 r.min-1,采用抄板气流流态控制和针滚机械干涉方法,均能使刨花处于良好的受胶状态,胶液均匀分布,提高板子的力学性能。  相似文献   

集材50A拖拉机搭载板升降机构的改进研究     

齐兴  刘长海 《吉林林学院学报》1994,10(3):194-198

对集材５０Ａ拖拉机搭载板升降机构进行牵引力及升降阻力的力学分析，揭示了原机构动力性与经济性不佳的设计问题，本着原机构变动不大的原则，把两只ＹＧ１１０／４０型液压油缸，改为一只ＨＳＧ１００／５Ｏ型油缸；把ＣＢ４６型油泵。改为ＣＢ－３２型油泵。改进结果表明简化了机构，优化了动力性，提高了牵引效率，每年可以使林业生产节约大量经营费用。  相似文献   

实验仿真板在毕业设计教学中的应用     

蒋淑霞 《中南林学院学报》2006,26(5):125-128

工科类单片机毕业设计中由于实验设备不足，不可能让每个设计都通过单片机的实验来验证，达不到毕业设计应有的效果．提出一种单片机实验仿真板Ledkey和Simboard并应用毕业设计教学中，以交通运输专业的单片机系统开发设计为例加以说明．结果表明，设计手段形象直观，设计成本低、效果好．该仿真实验板在单片机系统开发毕业设计中有着广泛的应用前景．  相似文献   

在Word与AutoCAD之间交换数据的研究     

张利军 《农业网络信息》2005,(11):109-111

Microsoft Word、AutoCAD是常用的文字处理软件和计算机绘图软件,它们的功能非常强大.本文主要介绍采用AutoCAD计算机绘图软件绘制的图形,转换到Word文字处理软件的常用方法.  相似文献