高温润滑脂轴承寿命试验台主轴临界转速分析

高温润滑脂轴承寿命试验台主轴需要确定其临界转速,以确保其在安全的转速范围工作,不发生共振。文章分析比较了常用的几种临界转速计算方法,采用有限元软件ANSYS对主轴临界转速进行计算。计算过程中考虑了轴承弹性支承对临界转速的影响,并使用弹簧阻尼单元模拟轴承弹性支承。结果表明,试验台最高工作转速远离临界转速,因而不会发生共振现象。     

不同径向载荷与转速下纺纱锭杆振动机理的仿真分析与试验

针对锭子高速运转时径向载荷过大、转速过高导致振动幅度过大,进而引起锭子失稳和磨损失效的问题,利用有限元模态分析与试验相结合的方法,研究径向载荷与转速对YD6103E型高速锭子振动特性的影响规律,阐明不同径向载荷与转速下纺纱锭杆的振动机理。结果显示,锭子转速为5 000 r/min时达到一阶临界转速,之后振幅逐渐衰减,10 000 r/min时达到一阶动态平衡状态,转速在10 000～15 000 r/min区间振幅逐渐增大,15 000 r/min时达到极大值后呈现下降趋势。这与有限元仿真结果基本一致。转速低于15 000 r/min时,5 kg的径向载荷可使锭子具有优异的振动性能,转速高于15 000 r/min时施加0.5 kg径向载荷的锭子具有更好的动平衡状态。     

立式碾米机主立轴的有限元分析

运用Solidworks软件建立碾米机主轴的实体模型,通过软件接口把模型导入到有限元分析软件ANSYS Workbench中,对碾米机主轴进行应力应变及模态研究,得到碾米机主轴的固有频率和振型,找出主立轴的应力分布规律和主要应力集中区域,分析了各阶振型得到碾米机主轴较为薄弱的地方和敏感部位,为后续的碾米机结构参数设计提供依据。     

基于有限元法的搅拌轴转子动力学分析

采用有限元方法对搅拌轴进行了临界转速计算以及模态分析,通过受力分析建立了搅拌轴简化的有限元计算模型的系统方程,对搅拌轴采用质点单元模型计算其临界转速并将结果与搅拌轴正常工作时的转速进行了比较,结果表明工作转速远离一阶临界转速,搅拌轴运转时工作平稳,振动幅度小;叶轮轮毂强度和加强板结构对桨叶的强度有较大影响。     

连续茶叶筛选和揉捻装置的评估(英文)

研究茶叶连续筛选、揉捻装置的设计、制造,并对其性能进行测试。在200℃条件下,分别将茶叶筛选装置和揉捻装置的转速设定在7～14r／min和34～68r／min范围内进行试验。结果显示最佳的试验条件是筛选装置转速10．8r／min,揉捻装置转速51r／min．当筛选量45kg／h和揉捻量18kg／g时,揉捻茶叶的产率最高,可以达到81％。     

木工安全平刨床噪声的初步探讨

木工机床的特点,是采用多刀多刃进行高速切削,特别是木工平刨床的主轴(刀轴)要达到4500-5000r/min,由于转速较     

基于ANSYS小型食品机械用电机转子模态分析

采用有限元方法对小型食品机械用电机转子进行了模态分析,得出该转子的固有频率,并相应求得该转子临界转速。将临界转速与工作转速进行比较,验证了该转子不易与其他部件发生共振,有较好的动态特性。     

不同玉米品种挤压膨化特性及工艺优化

采用均匀试验设计方法,应用响应面(RSM)分析了玉米品种、螺杆转速和物料水分含量对膨化率和挤压指数的影响,并建立了膨化率和挤压指数的二次多项式数学模型.根据此模型确定了最优的因素水平组合,工艺条件为:选择丹玉48,螺杆转速182 r/min,水分含量12%,可使膨化率达到4.0;选择玉米品种丹玉48,螺杆转速225 r/min,水分含量10%,可使挤压指数降低到66 cP.相关分析表明,螺杆转速和物料水分含量对挤压指数的影响比较显著.     

小型胚芽米碾米机工艺参数的试验研究

对影响胚芽米碾米效果的碾米机工艺参数进行了研究.以碾米辊转速、碾辊筋倾角和碾白室间隙为试验工艺参数,以留胚率、增碎率为评价指标,采用二次回归旋转试验设计,研究留胚率和增碎率在各参数影响下的变化规律.结果表明:碾米辊转速和碾白室间隙是影响碾米时留胚率和增碎率的两个主要因素,碾辊筋倾角次之;胚芽米碾米机最优工艺参数为碾米辊转速948 r/min、碾辊筋倾角0.86°、碾白室间隙11.2 mm.     

基于BP神经网络的花生挤压膨化参数优化研究

研究花生挤压膨化工艺参数对产品质量(粕残油率)的影响。通过建立BP神经网络模型,利用样本对其进行训练使其具有工艺参数-产品质量的映射能力,结合粒子群算法进行参数寻优,确定粕残油率最低时的最优参数组合。结果表明:建立了BP神经网络模型,相关的试验验证了仿真结果,表明BP神经网络模型在参数优化中的有效性和适应性;确定最优的参数组合为主轴转速55r/min、模孔直径12 mm、套筒温度105℃、喂料速度26 r/min、含水率11%和轴头间隙12 mm。在最优参数组合下,粕残油率为1.03%。模孔直径、主轴转速和套筒温度对产品质量的影响较大。     

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