基于PROFINET总线的造纸机传动系统设计

把PROFINET总线应用到纸机控制系统中,通过硬件设计实现整个控制系统的PLC配线和与变频器的总线通讯硬件连接,同时根据功能连接和总线通信的需要对变频器进行相关参数设置。在此基础上对纸机传动控制系统的软件编程思想进行设计,实现纸机传动中加减速等基本操作控制和速度链控制、负荷分配、张力控制等功能。     

基于PLC和触摸屏技术的纸机多段速度控制系统设计

设计了一种基于PLC和触摸屏技术的纸机多段速度控制系统.该系统以PLC为核心,对传感器采集的纸机实时数据进行存储、计算及传输,控制纸机的运行状态.同时与触摸屏进行通信,将纸机运行数据以动态图的形式显示,并接受触摸屏给定的工艺参数来控制执行元件,实现了操作人员与纸机的人机对话功能.通过模拟调试,该系统操作简单,智能化程度高,提高了产品质量及生产效率,并在一定程度上降低了能耗.     

纸机传动控制系统的配置与控制原理

针对纸机日益高速化、大型化的发展趋势,设计了国内先进的全数字化通信网络传动控制系统.系统采用西门子全集成自动化解决方案,实现造纸生产过程的全线集成控制.高可靠的工业现场总线PROFIBUS-DP和工业以太网相结合的网络结构,有效地实现了数据共享,全面解决了整个工艺过程的控制.文章详细介绍了控制系统的配置和功能,重点阐述...     

纸机横向定量控制系统中的数据交换方法

针对纸机横向定量控制系统,对其中存在的定量数据获取及控制输出数据的传送问题进行了分析,以VB软件作为工具开发上位机软件,基于OPC技术实现了与纵向定量控制系统之间的数据交换,并基于开放系统互联简化模型自定义通信协议,利用RS485串行接口通信实现了与执行机构之间的数据交换,从而对稀释水阀开度进行调节,实现对纸张横向定量的自动控制。     

造纸机控制系统及QCS、DCS的选择

对纸机控制系统作了简要论述，介绍了QCS系统技术参数，并从通信网络，操作站、控制站、I/O、工程师站及软件组态工具等方面对DCS系统作了一般技术性论述，指出纸机集成自动化控制系统是现代纸机的首选控制方案。     

SIEMENS传动在高速卷烟纸机系统的应用

介绍高速卷烟纸机传动控制特点,以西门子矢量控制变频器6SE70为驱动装置、PCS7为控制核心、TP200为显示单元,根据西门子PROFIBUS通讯协议,实现PLC与6SE70变频器的通信、纸机速度链、负荷分配等控制功能.在纸机控制系统中取得较高的控制精度和控制稳定性,充分满足生产过程需要.     

基于DeviceNet的纸机传动控制系统设计及应用

通过对纸机传动控制系统存在问题的分析,设计了以DeviceNet现场总线为通信方式、PLC为控制单元、操作屏为人机界面、PF700变频器为传动单元的纸机传动控制系统。具体探讨了系统中DeviceNet硬件组态、速度链控制、负荷分配计算等原理及应用。此系统在实际工程项目中得到验证,取得良好效果,解决了传动控制系统存在的问题。     

可编程计算机控制器在纸机传动系统中的应用

针对纸机的工艺特点，提出了以可编程计算机控制器(PCC)来实现传动控制系统的设计方案。这种方法充分利用了PCC的特点组成分层递阶式交流变频网络控制系统，大大节约了设计时间；由于PCC具有高的响应速度，强大的通信功能，并采用分时多任务处理方式，因而提高了纸机传动控制系统通信速度与质量，使得系统稳定性高、实时性好且易于扩展。     

微型断路壳上料控制系统设计

针对微型断路器装配过程中存在生产效率低、一致性差等缺点,提出了基于PLC控制器的微型断路壳上料控制系统。课题组设计了上料控制系统的机械结构,介绍了上料机构的组成和连接方式;采用伺服电机实现上料机构的精确控制;设计了上料控制系统的硬件组成以及工作原理;采用以太网的通信方式提高数据的传输速率;设计了控制系统的上位机显示界面。控制系统运行结果表明,断路壳上料机运行稳定、结构简单、成本低,有效提高了整个装配生产线的装配效率。     

Powerlink在纸机传动控制系统中的应用

介绍了一种确定性工业以太网Ethernet Powerlink,并利用贝加莱可编程计算机控制器(PCC)和伺服控制系统(ACOPOS),通过Powerlink,建立了纸机分层递阶式网络控制系统.经B&R Automation Studio软件编程,实现了多电机速度链同步传动控制.Powerlink的引入,大大提高了系统现场层和控制层的通信速率,降低了接线成本,减少了维护费用.实际运行结果表明,其控制稳定性好、可靠性高,较好地满足了高速纸机传动控制的精度和稳定性要求.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

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

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status