复卷机退卷张力自动控制系统设计

针对复卷机工作时退卷张力控制难的问题,在分析了退卷张力对纸幅质量影响的基础上,确定了退纸辊的控制要求并对控制方案进行合理选择,完成了复卷机退卷张力自动控制系统的硬件和软件设计。将公共直流母线结构应用于复卷机传动控制系统中,能充分利用再生能量,提高复卷机运行效率;对退纸辊控制部分进行软件模块化编程,使其具有普适性。该退卷张力自动控制系统在实际中的运用效果较好,适当改动即可适用于多种复卷场合下退卷张力的控制。     

交流复卷机退纸辊的控制策略

针对交流复卷机退纸辊传动的控制难点,分析了退纸辊电机的选型依据,提出了退纸辊正常运行时发电回馈的能量流向,建立了复卷机退卷纸幅张力控制的两种数学模型,并提出了两种退卷张力控制的方案。     

复卷机张力控制系统的设计及应用

针对复卷机退纸辊退卷张力控制系统中存在多扰动与非线性的问题,以退纸辊退卷张力为研究对象,提出一套完整的控制方案,在张力控制中引入了模糊PID算法,并加以应用。为解决交流传动下系统产生的回馈能量处理问题,对系统主电路硬件结构进行了公共直流母线设计,该设计已应用于浙江金华某纸厂复卷机项目的退纸辊退卷张力控制系统,取得了良好的控制效果。     

交流复卷机的间接张力控制

针对交流传动复卷机中影响间接张力控制的各因素进行了具体分析,给出了退纸辊交流电机在复卷机稳态运行和加减速运行时电磁转矩计算公式,利用现场总线技术控制退纸辊电机的变频器按照规定转矩运行就可以实现间接张力的控制。实际使用证明这种间接张力控制的方法可以接近直接张力控制的效果。     

再复卷机纸幅张力控制分析与应用

再复卷机退纸装置是由两台电机共同驱动一个退纸卷筒,针对再复卷机在复卷过程中车速增减以及退卷卷径的减小时对纸幅张力的影响,以退卷纸幅张力控制为研究对象,结合再复卷机工作原理,推导出退卷张力系统的数学模型。根据本次项目现场调试,提出再复卷机驱动退纸纸芯的两台电机采用主-从传动控制和光纤通讯。     

复卷机退纸辊转动惯量补偿问题的分析

复卷机退纸辊转动惯量的补偿可以保证张力恒定,从而保证了复卷的质量.分析了稳态和变速过程中造成张力波动的主要因素以及如何实时补偿转动惯量以保证恒张力控制,并提出了实际中基于欧陆590控制器的转动惯量补偿系统.     

国产机外高速涂布机自动接纸装置

设计了一种新型的高速自动接纸装置,采用双纸卷回转型退纸架和与纸卷不接触的新纸卷加速系统,通过进口气缸控制压辊动作及断纸,利用张力传感器或缓冲辊（浮动辊）来控制退卷张力。并采用多种形式的光电检测装置,在机外涂布机全速运行状况下,经一系列光电检测、PLC动作顺序控制、连锁控制,实现整个换卷过程的自动化。该高速自动接纸装置可以有效地保证机外涂布机的连续高车速生产,提高涂布机运行性能,已成功运用于国内20余台机外涂布机,实现了全速自动接纸,成功达95％以上。     

双底辊复卷装置的张力控制及其仿真

主要对双底辊复卷装置力学模型进行了分析，提出了前底辊半闭环张力控制和液压系统的控制方案，最后用双底辊复卷仿真系统完成模拟输入输出控制。     

Eurotech分条复卷与AVT100％全自动质量检测系统又一次成功落户苏州

近日，苏州某知名内资印刷企业成功安装第三台由博泰公司研发的Eurotech分条复卷与AVT100％全自动质量检测系统。Eurotech分条复卷检测系统采用闭环张力控制方式开卷，标准纠偏系统，纠偏及执行机构为欧洲原装进口品牌，高精度重型墙板，确保设备传动精密。Eurotech同时采用最先进的偏心式剪切分切刀辊，保证最精确的分切尺寸，     

Lenze EVF93变频器在罐蒸机上的应用

本文介绍了采用德国伦茨公司生产的EVF93变频器驱动罐蒸机上下辊筒,以实现包布恒线速度及张力、压力随上辊卷径按曲线变化控制的应用实例。     

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.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press