谈UV淋幕式平面涂装机的成幕

目前，UV淋幕式平面涂装机在我国尚处研制阶段，其成幕原理各说不一。就成幕而言，既可因重力自流而成，也可靠施加压力动压而成。本文根据分析计算和实例认为，适合竹木板材的UV油漆必须加压成幕。     

幸福堰引水工程中的双箱式取水及输水暗涵设计

 幸福堰引水工程的建设主要服务于巧家县金塘乡部分土地灌溉和人畜饮水，在整个工程中存在着许多特殊问题需要解决，其中，取水防沙是最关键的问题之一。介绍的设计方法成功地解决了取水、防沙等问题，为泥石流地区和水土流失严重地区取水防沙工程设计提供了好的参考。     

Cold tolerance in beans (Phaseolus spp.) as analyzed by their exotherms

Summary Cold tolerance of common bean (Phaseolus vulgaris L.), runner bean (P. coccineus L.) and several bean lines was evaluated under artificial conditions. Seedlings were exposed to –6°C gradually, then to –12°C rapidly in the growth chamber with copper-constantan thermocouples attached to various parts of the plant. Seedling freezing curves with exotherms were then analyzed. Three basic parameters were measured: time required for exotherm to appear, temperature of the appearance of the exotherm and temperature rise caused by the exotherm. Exotherm appearance in beans was related to freezing injury and death of the seedlings. Exotherms of the common bean variety Bush Blue Lake 92 seedling recorded at the stem, primary leaf base, tip and petiole and true leaf appeared at the same time, however their shape was different. Exotherms of stem appeared at higher temperature than those of primary leaves. Their shapes always followed the same pattern. Beans with cold tolerance were found to produce exotherms later than susceptible ones. Exposing 3 weeks old bean seedlings to 12°C delayed the time of exotherm appearance in the cold susceptible cultivar Bush Blue Lake 92. Some plants survived 2 hours exposure to –6°C in the growth chamber.     

压力传感器的计算机标定与测量

就流体技术领域中的压力传感器标定和测量方法进行了讨论，提出了工业现场情况下的采样技术，还对测量参数的非线性处理和计算机规范化进行了表述。     

超高压处理对鲜切山药片质量的影响

为研究适宜的鲜切山药片的保藏方法,采用超高压处理对鲜切山药片进行保鲜。将鲜切山药片分别采用0MPa、200MPa、400MPa和600MPa加压处理10min后,在4℃条件下贮藏9d,分析超高压处理对贮藏期间鲜切山药片中细菌总数、多酚氧化酶活性、褐变指数、可溶性固形物、总酸和维生素C含量的影响。结果表明:600MPa压力处理10min后,可抑制于褐变相关的多酚氧化酶,抑制微生物生长,产品在4℃条件下贮藏9d后,仍然可具有较好的理化指标,表明该法是一种较好的鲜切山药片的保藏方法。     

黑木耳块精加工工艺的研究

散装黑木耳容积林，重量轻，易破碎，是贮运的难题。本研究确定了黑木耳块的精加工工艺。通过软化，加压，干燥等项试验，分析了黑木耳的含水率，设备系统压力，环境温度等因素对黑木耳块加工的影响，确定了温度为１０－２５℃，含水率为２０％－２２％，压力为１１ＭＰａ是工艺最佳参数，根据此工艺，又确定了液压专用设备。     

磁控摆开式呼吸阀

机械呼吸阀是油罐的重要附件，几址年来我国油库使用的机械呼吸阀基本形式是阀盘在水平面内，靠自重或弹力控制罐内压力，阀盘工作时沿导杆升降。这种呼吸阀的主要问题是：沿导杆运动引起的机械故障多；阀盘自重大，使阀盘工作时开度小，通气量小，严重时造成油罐受损。     

不同径向间隙对离心泵动静干涉作用影响的数值模拟

通过改变蜗壳基圆直径改变叶轮与隔舌之间的间隙,采用SST模型对3个蜗壳基圆直径的离心泵全流道进行非定常数值模拟.3个蜗壳基圆直径分别为184、198和214 mm,其对应的间隙率为5.74％、13.79％和22.99％.通过非定常数值模拟获得了不同基圆直径离心泵的压力脉动特性、作用在叶轮上的径向力和扭矩特性,并对其进行比较分析.结果表明:不同测点的压力脉动、作用在叶轮上的径向力和扭矩呈周期波动,均以叶片通过频率为主;不同基圆直径泵叶轮上的径向力矢量图基本呈圆形分布;随着蜗壳基圆直径的增大,叶轮上的径向力先减小后增大,各测点压力脉动幅值逐渐减小,高频脉动也逐渐减少.同时针对蜗壳基圆直径为184 mm的泵进行数值模拟,并对该泵进行了性能试验,对比分析结果表明:数值模拟的结果是可信的.     

高压气动比例减压阀设计与仿真

提出一种高压气动比例减压阀,该阀由比例电磁铁控制的二位三通型滑阀式先导阀和活塞提升式主阀组成,通过压力传感器和控制器构成闭环电反馈控制,最高工作压力为31.5 MPa。该阀虽然存在少量先导耗气,但保证了压力调整的快速性和稳定性,克服了先导泄漏对减压阀的影响,避免了先导阀意外结冰的发生。在介绍结构及工作原理的基础上分析了该减压阀的特点,利用AMESim建立了考虑气源压力和负载流量波动的仿真模型。仿真结果表明:该阀在气源压力缓慢下降且负载流量大范围波动的情况下能实现稳定的压力输出,在不改变控制参数的前提下,当气源压力为31.5 MPa时输出压力可在1~30 MPa范围内稳定;先导阀预开口形式对压力精度影响较小,但应避免正开口以减少气体浪费;先导阀环形间隙高度控制在10μm左右较为合适。     

Uncertainties in static closed chamber measurements of the carbon isotopic ratio of soil-respired CO2

The δ¹³C of soil-respired CO₂ (δ_r) is frequently determined using static closed chamber methods. δ_r is obtained as the intercept of the least squares linear regression of δ vs 1/C*, where measured δ¹³C-CO₂ (δ) and volume fraction of CO₂ (C*) values of chamber headspace samples are used. Theoretically, we show that the variance of the estimate of δ_r can be reduced by extending the 1/C* interval of the regression towards (i) higher or (ii) lower values, or (iii) distributing the 1/C* values optimally within the pre-selected headspace CO₂ sampling time period. Experimental applications of these approaches indicated that: (1) lowering the initial CO₂ level, thereby increasing 1/C*, yielded a positive bias to the δ_r result. (2) It was feasible to obtain lower variance in the δ_r estimate by lowering 1/C* values through extended CO₂ sampling time. We also recommend that each chamber is sampled only once, mainly because this allows freedom to select the sampling times, in order to optimize the distribution of 1/C* values.