可程控制器及其在指接生产线上的应用

本文介绍了指接生产技术的国内外现状、发展趋势编程控制器的特点,并具体好可编程控制器在指接生产线开榫机上的应用。     

可编程控制器PLC在林产工业中的应用前景

作者详细地介绍了可编程控制器应用前景和发展趋势,通过具体实例分析比较了其功能性,可靠性及经济性。为推广使用可编程控制器提供理论依据。     

可编程控制器在自动灌溉系统中的应用

根据各种花卉栽培方式以及花卉的需水规律，应用可编程控制器自身的特点，对花卉进行合理的、有效的自动灌溉系统设计。简述了自动灌溉系统中常用的控制模式及分类，比较详细地介绍了应用可编程控制器的花卉自动灌溉系统的硬件设计方案、工作过程以及该系统的软件模块设计和设计说明。该系统应用可编程控制器，能简化硬件结构且达到节水目的。     

可编程控制器在指接设备中的应用

可编程控制器在指接设备中的应用（１５０８２２）黑龙江省方正林业造纸厂杨广武付东林（１５００８６）哈尔滨市电子计算技术研究所赵沛丰（１５００８６）林业部哈尔滨林机所毕武１前言目前，在国外进口的木材加工机械设备中，广泛采用可编程控制器来提高其控制系统的自...     

可编程控制器在林业中的应用

阐述了可编程控制器的定义，特点及应用范围，并列举了林业应用可编程控制器的实例。     

可编程控制器PLC在跳汰机风阀控制中的应用

介绍由可编程控制器PLC控制的跳汰机风阀控制系统,详细叙述了风阀自动控制的思想,以及各种跳汰参数的调整方法。     

结构用指接材的研究现状北大核心

通过对建筑材料结构用指接技术的研究,介绍了指接技术概念,概括了木材结构用指接材齿榫几何参数、指接形式、指榫嵌合齿类型、以及胶黏剂的选择、施胶情况、层间接头距离研究与发展现状,拓宽了指接用木材的适用范围,讨论了指接用木材的适用性,此指接材相关适用性内容包括:胶接性能好坏、木材本身强度对指接部位强度影响、胶层厚度对指接材强度影响、层间接头距离对整体指接构件影响,并探讨了结构用指接材今后可能的研发趋势。     

单自由度步进滑台控制系统关键技术

介绍一种基于FX2N可编程控制器和SH-20403步进电机控制器实现的单自由度步进滑台控制系统,并对其中的关键技术加以说明.实践证明,该控制方案经济、可靠、精确和实用,可广泛应用于各类单自由度控制系统.     

分段式精密卷绕控制系统在高速卷绕机上的应用

介绍了一种分段式精密卷绕控制系统。该系统采用日本明电舍公司生产的VT634精密卷绕控制器,内置变频驱动控制器和精密卷绕纺丝控制器,摩擦辊采用主动控制方式,配合西门子S7-200可编程控制器,完成全自动高速卷绕机的电机速度控制和机械动作逻辑控制。经过现场实际运行,证明整套系统具有系统响应速度快,速度控制精度高,丝束张力稳定,防叠丝效果好等特点。     

PLC在生物质燃料成型机液压系统的应用

介绍了利用西门子可编程控制器(PLC)与传感器相结合控制成型机液压系统,利用所编程序实现手动/自动双重控制.通过手动控制各个油缸动作,还可实现故障检测,增强了其可靠性及稳定性.     

集成材生产设备的选型和配属

以典型的集成材生产工艺流程为例,说明了集成材生产机的选型及生产能力平衡验算的方法,最后总结出配属的基本原则.     

集成材生产设备配属--布局和过程能力的验证

以典型示例说明了集成材生产设备布局的方法和过程能力的验证,并分析了影响过程能力指数的各变量之间的关系.     

Green gluing of oak wood (Quercus conferta L.) with a one-component polyurethane adhesive

Abstract

This research work presents a study on the properties of finger jointing green oak wood (Quercus conferta L.) using a one-component polyurethane adhesive. The effect of finger-joint orientation (vertical or horizontal fingers) was also examined. In general, the results from the measurements of modulus of rupture and modulus of elasticity of green-glued finger-jointed specimens indicated that the green gluing of a high-density species such as oak wood is feasible.     

The effect of number of joints on bending properties of laminated lumber made from poplar (Populus nigra)

Connection plays an important role in structural components and end jointing is one of the most common connections in structural applications.This study was designed to investigate some mechanical properties (MOE and MOR) of solid wood samples manufactured from poplar (Populus nigra),joined together through end jointing.As well,we studied combinations of lumber manufactured from 10-mm veneer,using a polyvinyl acetate adhesive.The results show that non-jointed lumber (control samples) have better bending properties (MOE and MOR) than jointed specimens and lumber made from laminated layers.On the whole,side-byside joints have a negative effect on the MOR and MOE of laminated products,which is more pronounced in the MOR.By increasing the number of joints,the properties of combination of three-ply,i.e.,bending strength and modulus of elasticity,decreased.     

软PLC开发平台总体设计及控制方案探讨

简述了软PLC的定义、特征及其系统的特点和组成,对PLC语言开发平台软件进行了需求分析,给出了用数据流图表示的软件逻辑模型、开发系统的总体设计结构,并探讨了软PLC技术在工业领域的应用控制方案,展望了软PLC技术的优势和发展趋势.     

PLC控制系统在MDF生产线中的应用

根据PLC控制系统在中纤板生产中的使用经验，比较了PLC控制与继电器控制的效果，简要分析了PLC控制对产品质量的影响，并提出了使用PLC系统应注意的事项及维护措施。     

Effects of summer drought and winter freezing on stem hydraulic conductivity of Rhododendron species from contrasting climates

We studied the limits to maximum water transport in three diffuse-porous evergreen shrubs exposed to frequent winter freeze-thaw events (Rhododendron maximum L. and R. catawbiense Michaux from the Appalachian Mountains) and to a severe summer drought (R. macrophyllum G. Don. from the Oregon Cascades). Percent loss of hydraulic conductivity (PLC), vulnerability curves to xylem embolism and freezing point temperatures of stems were measured over 2 years. Controlled freeze-thaw experiments were also conducted to determine the effect of thaw rate on PLC. During both years, native PLC was significantly higher in winter than in summer for R. macrophyllum. Seasonal changes in PLC were variable in both R. catawbiense and R. maximum. Only R. maximum plants growing in gaps or clearings showed higher PLC than understory plants. A rapid (2-4 day) natural recovery of high native PLC during the winter was observed in both R. maximum and R. macrophyllum. Compared with the bench-dehydration method, vulnerability curves based on the air-injection method consistently had less negative slopes and greater variation. Fifty percent PLC (PLC(50)) obtained from vulnerability curves based on the dehydration method occurred at -1.75, -2.42 and -2.96 MPa for R. catawbiense, R. maximum and R. macrophyllum, respectively. Among the study species, R. macrophyllum, which commonly experiences a summer drought, had the most negative water potential at PLC(50). In all species, stem freezing point temperatures were not consistently lower in winter than in summer. A single fast freeze-thaw event significantly increased PLC, and R. catawbiense had the highest PLC in response to freezing treatments. Recovery to control PLC values occurred if a low positive hydraulic pressure was maintained during thawing. Rhododendron macrophyllum plants, which commonly experience few freeze-thaw events, had large stem diameters, whereas plants of R. catawbiense, which had small stem diameters, suffered high embolism in response to a single freeze-thaw event. Both drought-induced and winter-induced embolism caused a significant reduction in hydraulic conductivity in all species during periods when drought or freeze-thaw events occurred in their native habitats. However, rapid recovery of PLC following freezing or drought maintained the species above their relatively low margins of safety for complete xylem dysfunction.     

浅谈沥青玛蹄脂碎石混合料SMA-13的施工

本文主要从沥青混合料的拌制、运输、摊铺、碾压成型、接缝等几方面对SMA路面施工进行了详细的论述,具有较高的实用价值。     

浅谈工程量清单报价势在必行

随着我国建设市场的快速发展,招标投标制、合同制的逐步推行,以及加入世界贸易组织（WTO）与国际接轨等要求,工程造价计价依据改革不断深化,实行工程量清单计价,是规范建设市场秩序,适应社会主义经济发展的需要。     

Finger joint performance of structural laminated bamboo member

The structural performance of finger-jointed laminated bamboo was investigated for two bamboo species by considering the finger length, profile orientation, lamination direction, culm growth height, and mechanical properties of bamboo materials. Based on the growth height variation and bamboo species, the best finger-jointed laminated bamboo was found for the lamina processed from the middle growth height of a moso bamboo culm with the finger profile shown on the width face of the beam. It was 38.7% higher in bending strength than the lowest group, with the lamina from the lower ma bamboo culm showing the finger profile on the thickness face of the beam. When considering the finger length and lamination orientation, the strongest finger-jointed laminated bamboo joined with an 18-mm finger, showing the finger profile on the width face of a vertically laminated beam was 50.1% higher in bending strength than the lowest group having a 12-mm finger showing the finger profile on the thickness face of a vertically laminated beam. The laminated ma bamboo showed higher finger-joint efficiency, 11.6%, than moso bamboo, and the members showing the finger profile on the width surface was 12.3% better in joint efficiency than that showing on the thickness surface of the beam.