PLC在数控车床控制中的应用

本设计是对SIEMENS 802C数控车床中PLC程序的控制应用以及PLC在数控车床中的应用进行分析说明。设计首先针对PLC系统的组成、特点和应用领域进行介绍。对PLC在数控车床中的功能和应用进行了概述,然后主要针对SIEMENS 802C在数控车床中的几种应用方法和如何控制数控车床进行阐述与探讨。     

浅析西门子S7-200PLC实现PID功能的技巧

西门子S7-200系列PLC是一种可编程序逻辑控制器。强大的指令集、灵活的配置和紧凑的结构使S7-200PLC能够控制各种设备以实现自动化控制的需求。而在工业控制中,使用PLC对模拟量进行PID控制以其高性价比、强抗干扰能力以及便于用户操作等特点在使用计算机(包括PLC)的数字控制系统和使用模拟量控制器的模拟控制系统中都得到了广泛的应用。本文主要分析在以PLC为控制器的闭环系统中实现PID功能的技巧。     

皮带输送机中综合安全控制系统的PLC应用

现如今，随着科技的发展，计算机越来越多的进入到人们的生产生活中，但是一些需要功能相对简单、设备运行稳定的工作这可以用PLC进行替代使用，PLC属于简化版的工业用计算机，通过使用PLC内部的编程软件，能够极大的简化控制过程，提高控制的稳定性。现今，PLC应经广泛应用于生产生活中的方方面面。文章将就PLC的特点以及其在煤炭皮带运输中的控制应用进行介绍。     

强化木地板自动包装线控制系统设计

针对强化木地板自动包装线的特点,提出了一种基于PLC的包装线控制系统设计方法。在对包装线中自主研制装置控制系统设计的需求分析基础上,根据控制的逻辑要求,给出了基于S7-200PLC的I/O分配表和控制系统软件设计顺序功能图。根据S7-200 PLC的联网性能特点,采用计算机和Profi bus总线实现了包装线的集成控制。     

水厂自动化的PLC控制探析

PLC是以计算机技术为基础的可编程控制器,具有编程简单、使用灵活、能耗低、易维护的特点,是当前工业生产自动化控制领域常用的技术之一。由于其抗干扰能力强,对于多种工作环境都有着较好的适应性,所以应用范围十分广泛。文章针对自来水厂自动化系统PLC控制有关问题进行探讨。首先阐述了自来水厂自动化控制系统相关功能,介绍了水厂处理流程,最后对PLC技术在自来水水厂自动化控制的应用进行了分析。     

应用PLC构成的隧道照明自动控制系统分析

就当今我国高速公路隧道照明系统进行分析,结合隧道照明的特点,提出PLC系统在高速公路隧道照明自动控制系统中的应用,并将其与手动控制进行对比,对PLC系统的结构和功能做出详细阐述,同时对系统硬件配置、系统软件设计进行详细分析,得出PLC工作原理以及操作方式,并总结出PLC在使用过程中显示出的优点,希望对我国高速公路隧道照明工程提供一定帮助。     

基于PLC的自动门控制系统的设计

基于PLC可靠稳定的特点,对自动门的控制系统进行研究。首先根据自动门的控制要求,选取合适的PLC型号及各部分组成硬件;其次列出I/O分配表,绘制工作流程图;最后进行软件设计,利用梯形图语言编写相应程序,从而实现自动门的自动开闭功能。     

区域能源站自控系统的设计

文章设计的区域能源站自控系统对象为软件园5期能源站,使用PLC采集传感器及变频器的数据,传递给上位机Win CC进行显示、分析之后,进行集中调度和优化控制,并将控制指令下达给PLC,通过PLC控制现场设备。设计内容包括冷冻水系统方案设计和冷却水系统方案设计,设计功能包括系统及设备运行安全监控功能、设备优化调度功能、冷冻水系统PID控制、冷却水PID控制、运行参数记录及查询功能、参数超限报警功能等。     

PLC自动化控制的应用

随着现代化进程的加快,工业水平不断发展、革新的今天PLC的应用越来越广泛,文章即使从PLC的构成和功能的分析入手,对PLC在自动化控制中的应用进行分析探讨,希望能够对有关PLC在自动化控制领域的应用发展有所帮助。     

台达20PM PLC成功实现包装制袋旧设备改造

台达PM系列PLC是台达集团推出的专门用于2轴运动控制的一大精品力作,是可实现逻辑控制和运动控制的多功能PLC主机,其灵活、高速、精确的高速定位、双轴线性及圆弧差补、电子凸轮、飞剪、追剪等强大的控制功能,在众多双轴控制领域获得了广泛的良好应用。台达DVP-20PM00D是一款具有运动控制专用功能的可编程控制器,其最大特点是PLC主机直接提供电子凸轮功能,所以有些场所直接称呼DVP-20PM00D为台达20PM运动控制器。     

常用消毒灭菌法及其机理与应用

介绍了采用消毒灭菌方法,有加热消毒法,紫外线辐射法和化学药剂消毒法。常用化学药剂有醛类、含氯消毒剂、醇类消毒剂以及高锰酸钾、生石灰等,阐释了消毒与灭菌两个概念的区别。     

Probiotics and prebiotics--perspectives and challenges

Owing to their health benefits, probiotics and prebiotics are nowadays widely used in yogurts and fermented milks, which are leader products of functional foods worldwide. The world market for functional foods has grown rapidly in the last three decades, with an estimated size in 2003 of ca US$ 33 billion, while the European market estimation exceeded US$ 2 billion in the same year. However, the production of probiotics and prebiotics at industrial scale faces several challenges, including the search for economical and abundant raw materials for prebiotic production, the low-cost production of probiotics and the improvement of probiotic viability after storage or during the manufacturing process of the functional food. In this review, functional foods based on probiotics and prebiotics are introduced as a key biotechnological field with tremendous potential for innovation. A concise state of the art addressing the fundamentals and challenges for the development of new probiotic- and prebiotic-based foods is presented, the niches for future research being clearly identified and discussed.     

European citizen and consumer attitudes and preferences regarding beef and pork

This paper presents the combined mid-term findings of the consumer research components of two EU Sixth Framework Programme integrated projects concerning meat, ProSafeBeef and Q-PorkChains. The consumer pillar of ProSafeBeef carried out eight focus group discussions in May 2008, in France, Germany, Spain and the UK. Q-PorkChains conducted a large-scale, web-based, consumer survey in January 2008 in Belgium, Denmark, Germany, Greece and Poland. The first project provides a set of qualitative data from a small cohort of focus groups and the second a set of quantitative data from a larger consumer sample. This paper draws together the main findings of both projects and provides a comprehensive overview of European citizens’ and consumers’ attitudes towards and preferences regarding beef and pork. In general, consumers consider meat to be a healthy and important component of the diet. Consumers support the development of technologies that can improve the health attributes of meat products and guarantee eating quality, but they have a negative view of what they see to be excessive manipulation and lack of naturalness in the production and processing of beef products. In the Q-PorkChains study consumer and citizen segments are identified and profiled. Consumer segments were built upon the frequency and variety of pork consumption. The citizen segments were built upon their attitudes towards pig production systems. Overall, the relationship between individuals’ views as citizens and their behaviour as consumers was found to be quite weak and did not appear to greatly or systematically influence meat-buying habits. Future studies in both projects will concentrate on consumers’ acceptance of innovative meat product concepts and products, with the aim of boosting consumer trust and invigorating the European beef and pork industries.     

益生素、益生菌与结肠癌

介绍了益生素和益生菌及其作用机理。在动物模型中，有大量的数据证实益生素和益生菌能够预防癌症．而在人体内还没有直接实验证据。它们抑制癌症的确切机理目前尚不清楚，其抑制机理可能是：肠道菌群代谢活动的改变，肠道理化环境的改变，潜在的致癌物质的黏附和降解，肠道菌群的改变、抗癌或抗诱变物质的形成、提高宿主的免疫应答、影响宿主的生理活动以及发酵不能被消化的食物并形成有益代谢产物。     

节能节水型印染助剂和设备的现状

从节能、节水、缩短工艺流程和环保的角度出发，介绍了国内外研制开发的一系列新型节能、节水型印染助剂和染整设备。     

毛霉型低盐速成豆豉工业化生产工艺与设备

本文介绍了毛霉型低盐速成豆豉的工业化生产工艺及生产线的关键设备。     

组学技术与果蔬采后质量和安全控制

果蔬可以提供营养, 有利于人类健康, 而果蔬的后熟及其与环境的相互作用会影响果蔬采后的质量和安全。对果蔬生物学过程的了解和掌握是减少果蔬采后损失和保障果蔬采后质量和安全的关键。在过去的10多年, 基于组学技术的系统生物学在了解果蔬后熟及其与环境相互作用的分子机制方面得到了越来越多的应用。本文对此做了细致的总结, 指出了存在的不足, 并提出了未来的发展方向。     

Heritability and correlations for body condition score and dairy form within and across lactation and age

The objectives of the current study were to investigate the relationship between body condition score (BCS) and dairy form and changes in genetic parameters for BCS and dairy form within and across lactations and age. Body condition score and dairy form were obtained from the Holstein Association USA, Inc. Records were edited to include those cows classified between 24 and 60 mo of age and between 0 and 335 d in milk (DIM). A minimum of 20 daughters per sire and 15 cows per herd-classification visit were required. The dataset consisted of 135,178 records from 119,215 cows. Repeatability, multiple trait, and random regression models were used to analyze the data. All models included fixed effects for herd-classification visit, age within lactations 1, 2, and 3 or higher, and 5th-order polynomials for DIM. Random effects included sire and permanent environment for all models. Random regression models included age at classification nested within sire or DIM and lactation number nested within sire. Genetic variance for both BCS and dairy form was lowest in early lactation and highest in midlactation. Genetic correlations within and across lactations were high. The genetic correlation between DIM 0 in lactation 1 and DIM 305 in lactation 3 was estimated to be 0.77 for BCS and 0.60 for dairy form. The genetic correlation estimate between 30 mo of age at classification and 50 mo of age at classification was 0.94 for both dairy form and BCS. The repeatability models appeared to generate accurate evaluations for BCS or dairy form at all ages and stages of lactation.     

原花色素及其开发应用

对原花色素的结构、化学特性、制备、分析方法、应用前景作一综述,并重点讨论其生理功能,为在功能性食品、药物、化妆品等领域的深入研究和开发提供参考。     

酚类物质的结构与性质及其与葡萄及葡萄酒的关系

酚类物质是一类大而复杂的化合物。葡萄与葡萄酒中常见的酚类物质可分为类黄酮和非类黄酮两大类，它们是葡萄中重要的次生代谢产物，与葡萄的抗病性、采后生理、贮存、保鲜等密切相关。葡萄酒中的酚类物质来自于葡萄果实、果梗、酵母代谢以及橡木桶，参与形成葡萄酒的味道、骨架、结构和颜色等，对红葡萄酒的特征和质量尤其重要。