基于三菱L02型PLC的污水处理控制系统设计

使用三菱L02型PLC作为新污水处理控制系统的主站,并基于CC-Link通信协议扩展从站FX3U型PLC。罗茨风机、自吸泵、搅拌器和螺杆泵等使用变频器进行驱动,所有变频器由FX3U型PLC运用三菱通信协议控制。污水的MBR工艺和SBR工艺使用PLC流程控制,并采用触摸屏组态和办公室上位机组态画面同时操作,并行响应输出。远程监控模块连接触摸屏通信口获取污水状态数据,可发送远程报警短信并通过网页远程监控污水处理站。这种新的污水处理控制系统运用了4类通信技术,降低了布线成本且简化了污水处理系统调试过程,从而提高了污水处理系统的闭环控制和远程监控能力,显著提高了污水处理的运行稳定性。     

基于USS协议的多电动机同步调速系统

介绍了一个由贝加莱的PCC与西门子交流变频器联网组成的多电动机调速控制系统。采用基于RS-485接口的USS协议实现了PCC与多台交流变频器的串行通信控制。该系统可以对各变频器的运行参数进行在线监测,并进行远程控制,能有效地减少系统布线、提高系统的抗干扰能力,为印染自动化提供了一个低成本和高性能的方案。     

钢丝表面处理生产线恒线速恒张力控制

钢丝表面处理生产线主要由放线机、清洗槽、张力机构和收线机组成,根据工艺要求,生产过程必须保证线速度和张力恒定。该生产线控制系统主要由汇川MD320变频器、光洋TRD-2T1000BF编码器、兰宝LR30CN15LIM位移传感器、NPN型接近开关组成。分述各组成部分的功能,说明生产线线速度和张力恒定的控制过程以及实现方法,线速度控制主要是通过安装在张力机构定轮的编码器检测的线速度与给定的线速度比较运算后实现,张力控制主要是通过安装在张力机构的位移传感器检测张力杆的位置,控制放线机的运行速度实现张力控制。给出生产线示意图、控制系统控制框图、变频器的参数设定。运行表明该系统稳定可靠,实用性强。     

浅析DCS与PLC通信

越来越多的现代化企业广泛应用DCS完成生产线的控制和操作,由于生产设备供应厂商不同,一条生产线可能会有超过两套控制系统。为了实现对整个生产线的完全控制和操作,不同的控制系统之间需要数据交换来完成系统之间的融合。本文就西门子S7-400与METSO DNA系统之间的通信,介绍了通过DP/DP耦合器来实现DCS与PLC间通信的方法。     

钢丝清洗生产线的电气控制

钢丝清洗生产线主要由放线机、张力架、清洗槽、烘干机、牵引机和收线机组成,收、放线的恒张力运行是电气控制的关键。电气控制系统主要由PLC、变频器、触摸屏、位移传感器、接近开关等组成,说明组成系统的硬件元件型号,论述收、放线的张力控制过程和实现方法,给出生产线示意图、控制系统框图、变频器的参数设定表及参数输入界面,运行表明,该系统稳定可靠,维修量少,实用性强。     

1880/150特种纸生产线自控系统设计

总结了1880/150特种纸生产线项目的自动控制系统设计及实施方案。该项目控制系统主要由冷凝水自动排放系统、自动配酸系统、中和水自动控制系统组成,实现了对液位的实时监测与联锁,从而实现对设备的自动控制。。     

基于INTERNET的现代造纸传动远程控制系统

在现代交／直流调速系统的基础上，结合电力电子技术、计算机网络技术、通信技术。实现由单机通讯控制、多机通讯控制到远程控制，对现代造纸传动系统进行远程控制和远程决策。     

纸机传动系统中Profibus-DP总线技术的应用

随着控制计算机通信、网络等技术的发展,引起了自动化系统的变革,逐步形成了以网络集成自动化系统为基础的企业信息系统.现场总线导致传统系统结构的变革,形成新型网络集成式全分布控制系统--现场总线控制系统(FCS).现场总线是控制系统与现场设备之间建立的一种开放、全数字化、双向、多位的通信系统.     

基于RFID和ZigBee技术的服装吊挂系统生产线设计

为提高服装吊挂系统的信息化水平,解决厂房布线繁琐问题,加强系统对生产线上各工作站的控制,提出一种融合射频识别(RFID)技术和ZigBee网络的服装吊挂系统生产线设计方法.系统利用超高频RFID读写器收集各工作站中的衣架数量及编号等信息,由ZigBee网络传送至上位机,根据后台数据库中衣架编号与服装裁片的对应关系,实时掌握服装吊挂生产线的各工序进展情况.实验结果表明,该系统可有效提高服装吊挂生产线的工作效率及管理水平.     

基于物联网的纺织空调智能化监控系统设计

传统纺织企业空调系统温湿度调节主要依靠操作人员的经验,自动化程度低,控制误差较大,通信联网功能弱,信息管理相对滞后。现代纺织企业对温湿度控制信息化水平的要求日益提高,构建了现代纺织温湿度控制物联网结构,设计了一种基于物联网的温湿度监控系统。系统由远程监控子系统、数据库子系统和现场监控子系统三部分组成。系统采用基于分布式CC-LINK现场总线、GPRS通信和计算机网络等技术,可现场和远程对环境数据进行采集与控制。结果表明,系统可稳定实现温湿度集中与远程控制,提高了企业生产和信息化管理水平,降低了劳动力成本,节能降耗效果明显。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the