人造板装备制造业最新进展及节能环保人造板设备研发方向

当今世界人造板制造基地发生转移,预示中国人造板装备市场将有突飞猛进的发展。我国人造板生产线劳动生产率的提高是永恒课题,节能环保是人造板装备的研发方向,人造板生产线无人化是未来技术进步的理想目标。     

基于自适应LS-SVM的柴油机废气再循环冷却控制系统设计

针对当前柴油机废气再循环冷却控制系统受到时滞问题影响,导致系统开度走势与设定走势不一致、废气再循环效果差的问题,提出基于自适应LS-SVM的柴油机废气再循环冷却控制系统;以AT89C51单片机40针作为电控单元核心部件,利用位置传感器向系统发送负载信号,利用温度传感器来传输信号并反馈至D/A转换器;在D/A转换器中,反馈信号以串行或并行方式进入寄存器,并在转换后输出电流电压,控制系统阀门在排气再循环时的开启;伺服泵采用冷却系统,为系统提供液压动力源;利用自适应LS-SVM原理计算柴油机废气再循环冷却控制目标边界值,在最小二乘支持向量机基础上,利用求解线性方程组进行优化,消除了控制误差;根据控制差的大小,调整控制系统的输出值;由试验结果可知,该系统开度走势与设定开度走势一致,且与设定开度误差为1开度,说明使用该系统具有良好稳态特性,有效克服了系统中时滞问题,废气再循环效果较好。     

复合材料翼盒壁板低速冲击接触力、凹坑特性及其模拟

为预测复合材料层合板的低速冲击特性,提出一种基于弹簧-质量模型的冲击分层响应模拟方法。首先根据假定的分层数量和分层面积计算分层前后的弯曲刚度与挠度变化,进而模拟出含分层过程的冲击头运动时间历程。然后,由冲击头的加速度计算接触力,并基于材料的弹-塑性接触定律计算出永久凹坑深度。随后,对共固化复合材料翼盒的壁板进行了低速冲击实验,冲击点分为3种类型:2个梁间蒙皮的中点位置、蒙皮与翼梁T型连接的胶接区边界和梁的正上方。接着,分析对比了不同冲击点的接触力、分层阈值力和凹坑深度的特点。最后,使用所提出的模型计算第1种冲击点的接触力、永久凹坑深度和吸收能量,并分析了矩形板长宽比对薄膜刚度及接触力的影响。结果表明:模拟的接触力与实测结果吻合良好,对永久凹坑深度和吸收能量的模拟精度也较高,所提模拟方法有效;随着长宽比的减小,薄膜刚度迅速增大,从而使接触力显著增大。      

论我国人造板生产企业对环境的污染及其治理

回顾了湿法纤维板生产的环境污染及其治理状况,认为其科研成果和经验对干法纤维板生产仍有很好的借鉴作用;指出在我国人造板蓬勃发展的今天,人们在重视产品的产量、质量和经济效益的同时,更应重视对环境的保护。     

脱胶缺陷尺寸对复合材料加筋板屈曲及后屈曲特性的影响

为确定脱胶缺陷对复合材料加筋板屈曲及后屈曲特性的影响,对含不同脱胶缺陷工型筋条的复合材料加筋板进行了压缩试验研究。结果表明,30 mm和50 mm的缺陷对试验件承载能力影响很小,当缺陷尺寸增至80 mm时,试验件后屈曲承载能力明显下降。借助超声检测技术对缺陷的扩展行为进行了监测,结果表明,当压缩载荷达到破坏载荷的85.3%时,预制缺陷的对角位置处出现扩展迹象。通过影像云纹法获得两半波和三半波失稳模态的形成过程。对失稳模态的监测结果还表明,随缺陷长度增加,该型加筋板的失稳模态从三半波向两半波转换。在试验基础上,利用ABAQUS软件建立有限元（FE）模型,依次进行了屈曲及后屈曲过程的数值模拟。屈曲分析用于获得试验件的失稳载荷及模态,在后屈曲分析中将失稳波形以几何扰动的形式引入FE模型,最终计算结果与试验结果基本吻合,表明该模型可以用于复合材料加筋板屈曲及后屈曲性能的预测。     

State-space approach for statics and dynamics of angle-ply laminated cylindrical panels in cylindrical bending

Elasticity method is developed to study the bending and free vibration of simply-supported angle-ply laminated cylindrical panels in cylindrical bending. The present analysis is completely based on the state-space formulations, which is very effective for laminated structural analysis. In particular, exact solution is derived for the static bending problem by virtue of a variable substitution technique. Approximate analytical solution is derived for dynamic problem by employing the layerwise method. Numerical results are finally presented. The current study should serve as a necessary supplement to related works in the literature.     

On crystal size and cooling rate

A theoretical model is proposed which is used to derive a quantitative relationship between the critical cooling rate and average crystal size at any location within a biological specimen of given shape subject to rapid freezing. The model is applicable to the slamming, plunging or spraying methods of cryofixation provided the ice crystal size is at least 5 times greater than the size of the critical nucleus. Complete vitrification of pure water or aqueous solutions is shown to take place at cooling rates in excess of about 3 × 10⁶ K/s.     

Development of a Knowledge-Based Process Planning System for an Auto Panel

Challenges and pressures from the growing globalisation of markets have made automotive enterprises shorten the product development cycle time and reduce costs through the increasing use of mathematics-based tools and processes. In order to bridge the gap between experience-based design and science-based engineering, this paper establishes a knowledge-based process planning system to fully support auto panel die development and design automation. The framework of this novel system is proposed, and key issues, such as knowledge acquisition, knowledge representation and knowledge-based design are described in detail. The function model of the system is proposed to illustrate the architecture and functionality of the system. The system provides users with just-in-time access to the appropriate knowledge and information to reduce the search burden. A practical example is used to show the great advantage of the knowledge-based process planning system.     

高性能图像传感器参考设计的核心集成与协作

ADI公司与滨松光电子公司合作,建立了高性能模拟前端(AFE)板,与Hamamatsu G920x线性阵列NIR/SWI InGaAs图像传感器系列接口。920x系列图像传感器包括一个集成热电冷却器(TEC),用于冷却光学探测器,支持超低噪声操作,这使其成为高性能NIR/SWIR光谱应用(如天然气和矿物鉴定)的理想选择。     

Evaluating the thermal reduction effect of plant layers on rooftops

This study examines the thermal reduction effect of plant layers on rooftops through experiments performed in a controlled environment. The relevant parameters are coverage ratio (CR) and total leaf thickness (TLT). Both parameters are positively correlated with thermal reduction ratio (TRR). The TRR data of all experiments were plotted on a grid system with CR on the x-axis and TLT on the y-axis. A TRR map was then drawn using the curve fitting process. The applicability of the TRR map drawn for Codiaeum variegatum (1) was further confirmed by performing experiments with Cordyline terminalis (1) and Ixora duffii (1) and by results of experiments on C. variegatum (2), C. terminalis (2), Duranta repens, and I. duffii (2) in outdoor environments. The TRR map provides quantitative and straightforward guidance on thermal reduction planting arrangements for green roofs.