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为准确探究运动副间隙影响下的四连杆打纬特性,文章将筘座上的打纬阻力以等效扭矩形式转化至摇轴,并通过Step函数模拟和加载等效扭矩。以运动副间隙矢量模型为依据,利用ADAMS/View对含间隙双侧四连杆打纬机构进行多体动力学建模,并在刚体接触条件下实现不同间隙机构的仿真分析。结果指出:筘座角加速度偏离幅度会随运动副间隙增大而增大,极小间隙(00.1 mm)时,不仅会产生较大的轴承碰撞力和机架冲击载荷,而且筘座角加速度和角位移也会发生明显偏离,容易造成织口布面振荡,不利于打紧纬纱和改良织物质量。通过研究可为含间隙四连杆打纬机构的仿真设计提供重要参考。 相似文献
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针对喷气织机四连杆打纬机构随着转速的不断提高会引起的强烈振动和噪音问题,采用理论分析、数值模拟和实验相结合的方法对打纬机构及墙板的振动特性进行研究。分析四连杆打纬机构的动力学特性,基于有限元法分析四连杆打纬力对织机墙板振动的影响,建立打纬机构的曲柄旋转角度与打纬力、织机墙板最大振动应力和加速度的关系,确定织机墙板上最大振动以及最大应力产生的位置。结果表明,墙板发生共振的频率约为44?5 Hz,与喷气织机主振频率非常接近,墙板的最大振动主要集中在打纬机构附近,而最大应力主要集中在墙板中部和下部,并非墙板的最大振动处。 相似文献
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四连杆打纬机构的优化设计 总被引:3,自引:0,他引:3
本文首先分析了有梭织机四连杆打纬机构与其他机构在运动配合上存在的问题,得出了具有急回特性的四连杆打纬机构能有效扩大梭子穿越梭口飞行角的结论。然后以1511织机为例,用机构优化设计方法重新设计了四连杆打纬机构,其结果可作为老机改造或新机设计的一个良好方案。 相似文献
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本文推导了四连杆打纬机构尺寸偏差和筘座在前止点时位置关系式。对Smit TP300织机的打纬机构及常用的各种四连杆打纬机构作了前止点位置时的位移误差分析,提出了四连杆打纬机构尺寸偏差的选择方法。 相似文献
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前言织机上的打纬机构大都采用四连杆型式的打纬机构。由于四连杆打纬机构结构简单,制造方便,运转灵活可靠,能较好地满足工艺要求,因此不仅在传统的有梭织机上使用, 相似文献
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1511-1515型系列的织机均为四连杆非轴向打纬机构,该机构的非轴向偏距e值表征了筘座的运动性能,在设计和运动分析时需加以精确计算,为此本文推导出适用于各种四连杆打纬机构的非轴向偏距e的计算公式。一、e值计算公式的推导四连杆打纬机构如附图所示,曲轴A回转时,曲柄AB通过牵手BC带动筘座脚CD,绕摇轴D作往复运动。当曲柄处于前、后止点时,牵手栓分别位于C、C′点,过A点作直线CC′的垂线交于 相似文献
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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. 相似文献
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John Gilbert Catherine Simoneau David Cote Achim Boenke 《Food Additives & Contaminants》2000,17(10):889-893
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. 相似文献
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Yoko Uematsu Keiko Hirata Kumi Suzuki Kenji Iida Kazuo Saito 《Food Additives & Contaminants》2001,18(2):177-185
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. 相似文献
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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. 相似文献
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Sophie Guillot Laurence Peytavi Sylvie Bureau Renaud Boulanger Jean-Paul Lepoutre Jean Crouzet Sabine Schorr-Galindo 《Food chemistry》2006
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. 相似文献
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Jesus Simal-Gandara Miguel Sarria-Vidal Arjen Koorevaar Rinus Rijk 《Food Additives & Contaminants》2000,17(8):703-711
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. 相似文献
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Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates 总被引:2,自引:0,他引:2
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. 相似文献
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Dupuis L Manfait M Serpier H Capon F Kalis B 《International journal of cosmetic science》1997,19(1):37-44
This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration. 相似文献
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《印刷工业》2014,(6):95-95
Operation of printing machine industry was still unsatisfactory in the first quarter of 2014.Analysis on operation of printing machine industry.a.Market demand was not strong;sales of product undulated and declined.According to the statistics,the total industrial output value fell by 19.28% in the first quarter of 2014 than the average quarter value in 2013; industrial added value decreased by 4.16%; sales revenue dropped by 22.83%. h. Business operation of enterprises was in poor condition. c. R&D of new products is an important transformation guarantee for enterprises. d. To take self explore new ways upgrading advantages,and explore new ways. 相似文献