工字钢腿腰延伸系数均匀分配的计算方法

对轧制工字钢采用一种新的腿腰划分方法，用计算机迭代计算，使腿腰延伸系数趋于均匀更趋于实际，使孔型设计更为合理。     

行列式制瓶机的使用与维护

本文以国产单滴行列式制瓶机为研究对象,对行列式制瓶机使用技术、维修技术进行较为全面的论述,探讨以提高行列式制瓶机完好率和利用率,降低故障停机时间,提高企业经济效益为目的的行列式制瓶机技术管理模式。     

关于I/O模拟的讨论

详细分析Windows的I/O机制,提出了分别在用户级、系统级、驱动级的I/O模拟操作,通过实际案例和源代码分享在I/O模拟上的得失,着重介绍鼠标与键盘的模拟。     

基于嵌入式技术的带式输送机控制系统

针对基于PLC的带式输送机控制系统存在体积大、PLC程序更改不方便、成本高等问题,提出了一种基于嵌入式技术的带式输送机控制系统的设计方案;详细介绍了该系统中嵌入式本质安全控制机、控制驱动器、远程I/O模块的硬件及软件设计。实际应用表明,该系统解决了基于PLC的带式输送机控制系统存在的问题,具有较好的稳定性、灵活性和友好性。     

基于I~2C总线的AD7745控制与读取方法

AD7745是一种响应快速兼超低功耗的高精度电容数字转换器,其采用的通信总线I2C是一种简单双向的两线制同步串行总线,它只需要一根数据线和一根时钟线即可实现连接器件之间的数据传送,但目前广泛应用的51系列单片机均不具有这种接口;文章详细研究了AD7745芯片内部的测量原理及寄存器配置方式,设计了其与单片机的硬件连接电路,使用STC89C52RC单片机的两条普通I/O线,通过软件编程模拟I2C总线所要求的操作时序,实现了对AD7745的控制与数据读取;同时,给出了其中关键程序,调试结果证明了该系统的有效性与稳定性。     

多虚拟机环境下磁盘写优化机制

在虚拟化环境下,如何在写直达法和写回法之间做出权衡以使系统既具有较好的可靠性又具有较高的磁盘读写性能,是一个亟待解决的问题。本文提出了基于XEN的兼有写直达法和写回法优点的磁盘数据写操作方法。通过修改虚拟机块设备前后端驱动程序,在虚拟机管理器中为每个虚拟机建立块级别的虚拟机磁盘缓存。虚拟机中的应用程序均采取写直达的方式,将数据直接写到位于虚拟机管理器的虚拟机磁盘缓存中。结果表明,该机制能为虚拟机提供高效率的磁盘读写操作,同时,在虚拟机系统突然宕机时也能保证用户数据的完整性和可靠性。     

Ethylene and Nitric Oxide Involvement in the Regulation of Fe and P Deficiency Responses in Dicotyledonous Plants

Iron (Fe) and phosphorus (P) are two essential elements for plant growth. Both elements are abundant in soils but with poor availability for plants, which favor their acquisition by developing morphological and physiological responses in their roots. Although the regulation of the genes related to these responses is not totally known, ethylene (ET) and nitric oxide (NO) have been involved in the activation of both Fe-related and P-related genes. The common involvement of ET and NO suggests that they must act in conjunction with other specific signals, more closely related to each deficiency. Among the specific signals involved in the regulation of Fe- or P-related genes have been proposed Fe-peptides (or Fe ion itself) and microRNAs, like miR399 (P), moving through the phloem. These Fe- or P-related phloem signals could interact with ET/NO and confer specificity to the responses to each deficiency, avoiding the induction of the specific responses when ET/NO increase due to other nutrient deficiencies or stresses. Besides the specificity conferred by these signals, ET itself could confer specificity to the responses to Fe- or P-deficiency by acting through different signaling pathways in each case. Given the above considerations, there are preliminary results suggesting that ET could regulate different nutrient responses by acting both in conjunction with other signals and through different signaling pathways. Because of the close relationship among these two elements, a better knowledge of the physiological and molecular basis of their interaction is necessary to improve their nutrition and to avoid the problems associated with their misuse. As examples of this interaction, it is known that Fe chlorosis can be induced, under certain circumstances, by a P over- fertilization. On the other hand, Fe oxides can have a role in the immobilization of P in soils. Qualitative and quantitative assessment of the dynamic of known Fe- and P-related genes expression, selected ad hoc and involved in each of these deficiencies, would allow us to get a profound knowledge of the processes that regulate the responses to both deficiencies. The better knowledge of the regulation by ET of the responses to these deficiencies is necessary to properly understand the interactions between Fe and P. This will allow the obtention of more efficient varieties in the absorption of P and Fe, and the use of more rational management techniques for P and Fe fertilization. This will contribute to minimize the environmental impacts caused by the use of P and Fe fertilizers (Fe chelates) in agriculture and to adjust the costs for farmers, due to the high prices and/or scarcity of Fe and P fertilizers. This review aims to summarize the latest advances in the knowledge about Fe and P deficiency responses, analyzing the similarities and differences among them and considering the interactions among their main regulators, including some hormones (ethylene) and signaling substances (NO and GSNO) as well as other P- and Fe-related signals.     

I.L.B.装置在小电网下大型管磨机启停控制中的应用

大型管磨机启停时电压会波动，常规方法是采用一台液体电阻启动器来保证电机启动过程平滑、无冲击。而在小电网下，此法却不尽人意。在越南某水泥粉磨站的水泥磨主电机的供电系统中，成功地将I.L.B装置与液体电阻启动器结合起来，收到事半功倍的效果。     

墩头超长实用堰泄洪安全分析及模型试验验证——以缅甸DAPEIN(Ⅰ)水电站工程为例

以缅甸DAPEIN(Ⅰ)水电站工程为例,论述了将WES实用堰的闸墩墩头向上游超长延伸之后,对泄洪安全所造成的影响。针对WES实用堰流量系数、堰面动水压力容易受边界因子影响的特点,对设计断面的堰顶布置和墩头形状进行了优化。根据堰面空化数计算公式及水流特性推导出计算的关键部位,对空化数进行计算。采用几何比尺为1∶60的物理模型对溢流堰的泄流能力和堰面动水压力进行了试验测试。试验结果表明:溢流堰的模型试验泄流能力和设计泄流能力非常相近。堰面动水压力除工况2的B4测点出现了-1.2 k Pa的微小负压值外,其余堰面时均压强值均大于0。从而,在泄流能力和堰面动水压力两方面都验证了这种设计方案的合理性。该工程所遇到的结构布置问题在中低溢流坝工程中属常见问题,解决思路可为今后类似工程建设借鉴参考。     

锦屏一级水电站左岸1601m廊道岩体质量指标研究

岩石质量指标(RQD)是评价岩体质量的一个重要参数,被广泛应用于岩石质量评价,但通过钻孔取芯方式获取RQD存在明显不足,给岩体质量评价带来了一定的误差。以锦屏一级水电站左岸廊道岩体为实例,结合结构面三维网络模拟技术,采用测线法研究了广义RQD_t随测线布置长度与角度的变化情况。在此基础上分析了岩体的尺寸效应和各向异性。研究结果表明:RQD_t存在显著的尺寸效应,随着测线长度增大至10 m,RQD_t收敛于一个稳定的值;随着测线倾向和倾角的变化,RQD_t沿空间不同方向呈现出不同的分布。研究发现锦屏一级水电站左岸1 601 m廊道岩体具有显著的尺寸效应和各向异性,基于广义RQD_t的岩石质量指标能克服传统RQD在这方面的不足。