基于ESO的小径木双面连续式纵向刨切机切削机构的结构优化设计

在结构设计中,为了解决寻求改变结构的厚度提高机构固有频率的最适宜部位、总体质量最小的问题,文章分别提出基于刚度或位移约束的机构拓扑优化、基于应变的结构拓扑优化的方法。首先提出通过ESO评价出了在静态结构中各单元对整体刚度灵敏度以及应变灵敏度,建立刚度-应变-质量的结构拓扑优化模型。通过ANSYS对小径木双面连续式纵向刨切机切削机构模态分析,得到其各阶固有频率,并通过此优化模型对机构进行优化,得到质量最小且机构工作频段远离固有频率的机构结构。并通过ANSYS对调整前后结构参数对比,验证此模型的有效性,对结构设计具有一定的指导意义,免去了繁琐高频次的实验解法,高效准确地提供了有效的优化方案。     

木质家具拓扑优化设计研究

减重以及探索新型结构,是家具结构设计中的重要问题,也是将增材制造应用于家具生产制造中的前提。在一定的外载荷和合理的约束下,减少家具的重量以及获得最优的材料分布,最广泛使用的方法就是拓扑优化设计方法。本文利用Solid Thinking inspire拓扑优化软件,对靠背椅三维模型施加有效的载荷和合理的约束,得到6种不同的靠背椅概念结构雏形,用于后期产品方案的深化以及对接增材制造。研究表明,拓扑优化是创新家具结构和家具设计方法的有效途径,可以为家具生产厂家开发新产品提供思路。另外,对家具产品三维模型外载荷和约束的正确施加,是得到最优拓扑设计的关键,也是研究的难点之一。     

齿啮式快开门装置上法兰的拓扑优化

为设计出更合理的快开门装置上法兰结构,文章利用拓扑优化技术对上法兰结构进行优化设计。根据快开门上法兰的受力与约束情况,对某蒸压釜上法兰的原始结构进行了静力分析,并根据分析结果建立上法兰的拓扑优化概念模型;在上法兰拓扑优化结果的基础上,根据加工制造要求对上法兰进行了二次设计;将二次设计后的上法兰新结构与原始结构进行对比分析。结果表明:新结构在最危险截面处一次局部薄膜应力和一次加二次应力均有所下降;并且,质量较原始结构减轻了23.2%。     

家具产品拓扑优化研究

中国正在由家具制造大国向制造强国迈进,传统家具结构设计方法已满足不了当今设计的需要,亟需采用更加科学高效的新方法,计算机技术的迅速发展及拓扑优化的出现,使这种需求成为可能。本文介绍了家具产品拓扑优化的的研究现状,分析了拓扑优化对家具减重、探索家具新结构、创新家具设计方法、对接增材制造的意义,介绍了家具产品拓扑优化的一般步骤,总结了家具产品拓扑优化目前存在的问题和未来发展趋势。     

新型直压式弹簧加压摇架的研制

介绍了普通弹簧加压摇架的结构特点及存在的不足,分析了新型直压式弹簧加压摇架的结构及在加压组件、锁紧机构、紧固机构、调压方式、掀起角度方面进行的改进及其优点。指出:新型直压式弹簧加压摇架具有结构简单、安装方便、压力稳定一致等优点,是弹簧加压摇架的发展方向;必须保证新型摇架各零部件选材、制造精度及装配精度达到要求,才能发挥其优良性能。     

经纱张力调节机构的拓扑优化设计与疲劳分析

为提升经纱张力调节机构的动态补偿能力，适应三维间隔织物剑杆织机的高速化织造需要，引入可吸收应力的变刚度气动肌腱作为原动件，设计了一种新型经纱张力调节机构。采用有限元技术对该机构进行了静力学分析和模态分析，得到其静态特性及前六阶固有频率阵型，在此基础上采用变密度法对机构进行拓扑优化，随后根据优化结果在SW中进行结构优化并采用有限元仿真实验进行验证。结果表明：拓扑优化后的机构可以减重13.32%,同时应力、应变和固有频率等静动态性能均有较大提升，其最小疲劳寿命可达17.91年，满足织机使用年限的需要。最后在VSI系列样机上进行了对比实验，分析优化前后的张力采样曲线。实验结果表明优化后的织机经纱张力波动更加平稳，机构动态特性有效提升。     

超高速硬盒包装机的多工位转盘拓扑优化设计

针对超高速硬盒包装机多工位转盘在自重较大、超高速及多工位复杂载荷的条件下,其运动惯性冲击大和结构动态特性要求高的问题,分析了在额定工况下多工位转盘的工作载荷与约束,利用ANSYS Workbench平台对原型结构进行了有限元分析模型的构建,通过拓扑优化技术计算了多工位转盘在设计域中的最优拓扑优化材料分布特征,并以拓扑优化迭代结果的密度云图和几何模型为指导,运用梯度环形带与加强筋和梯度弧形槽与减重孔两种设计思路获得具有对称结构的多工位转盘优化设计方案。结果表明：梯度环形带与加强筋结构优化方案可同时满足静力学及结构固有频率要求,该优化方案质量较原型减少了16.33%,最大等效应力降低了11.25%,动态比刚度效能提高了4.14%。     

基于Autodesk Inventor ANSYS的汽车曲柄连杆传动件有限元分析

曲柄连杆传动件是汽车的动力传递关键机构,其设计质量的好坏直接关系到发动机传递动力的效率,而且传动件承受交变的机械载荷和热载荷作用,是汽车部件中工作条件最恶劣的零件。通过应用Autodesk Inventor ANSYS系统对已构建的机构进行模拟实际环境的应力分析,确定危险应力及应力集中位置,实现了对曲柄连杆传动件结构的优化设计。该方法对于提高曲柄连杆传动件的设计质量,延长使用寿命具有重要的作用。     

梳理机工作辊结构的优化设计

为提高国内梳理机工作辊在缠绕针布和重力作用工况下的直线度,采用ANSYS软件对现有国产某型号工作辊的机械结构进行研究和分析,并在此基础上对梳理机工作辊进行优化设计。首先建立工作辊拓扑优化和尺寸优化数学模型,推导拓扑优化数学模型中目标函数对设计变量的敏度。然后根据分析研究结果,针对工作辊机械结构提出二步优化方案,基于ANSYS软件采用自编优化程序对工作辊进行拓扑优化和尺寸优化。研究结果表明:优化后的工作辊材料分布达到最优;在满足应力约束的条件下,工作辊最大挠度由原结构的0.33 mm减少到优化后的0.11 mm,减少了67%,优化后工作辊直线度和性能得到提升。     

改进整体式尼龙调节架

介绍细纱机中锭带张力的形成及相关部件结构,对支臂、调节架等主要零件的工艺性进行了分析,提出了结构优化设计的方案;通过实测试制件的变形量,探讨整体式尼龙调节架的结构和特点;指出,采用尼龙一次注塑成形的支臂和调节架,避免了切削加工等工作,脱膜便利,结构精致,降低成本,节能降耗,符合绿色制造的现代理念。     

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.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.     

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%.