30000kN纵梁压机分立同步系统的研制

为满足大型汽车纵梁成形工艺要求,用六台5000kN四柱液压机组装成30000kN纵梁压机。该机长达10m,六段横梁同步平移。该机采用分立同步方案。以电液比例阀、位移传感器和集成油路等元件控制各分立系统的流量关系,将各单机系统的位移信号输送到比例模拟放大器,进行整理发出误差信号,反馈到各机进行修正,进而控制活塞作同步动作。实验证明,同步精度达到了预想的结果。分立同步系统特别适用于中小型单机的组合。它既能发挥原机的功能,又不破坏原机的安装,实现不同的组合、形成不同吨级、不同尺寸的压机。     

Influence of the position relationship between gas–liquid interface and laser focus on plasma evolution characteristics in jet LIBS technology

In order to understand the characteristics of breakdown process, plasma evolution and spectral emission in liquid jets laser-induced breakdown spectroscopy methods under the influence of the position variation between laser focus and gas–liquid interface, this work takes the plasma generated by laser-induced liquid jets as the object of study and discusses the changes in the spatial and temporal evolution characteristics and spectral radiation of the plasma when the position parameters between t...     

我国畜牧业连续十七年步步登高

我国畜牧业连续十七年步步登高１９９５年肉类总产量５０００万吨，生猪存栏４．１４亿头，羊存栏２．７３亿只，大牲畜存栏１．５９亿头日前公布的国家统计局关于１９９５年国民经济和社会发展的统计公报表明，我国畜牧业生产连续十七年持续增长，肉类总产量明显增加，但...     

松下NV-A5EN摄录一体机故障检修两例

<正> [例1]故障现象 电源打不开,指示灯不亮。 分析与检修 整机加电不工作,说明电源和系统控制电路存在故障。首先拆机检查电源电路和系统控制电路的供电电压均正常,说明电源电路基本正常,而故障主要在系统控制电路。系统控制电路IC6001(MN6755486)正常工作,除供电电源正常外,还必须有正常的复位脉冲,为此,检测IC6001复位(25)脚电压是否正常(电路如图1),测得(25)脚电压为1V,     

胶原蛋白吹破美丽神话

胶原蛋白,是影响人体成长环境所必需的一种生物性高分子物质。近年来之所以被很多消费者所熟知,主要是因为它在改善皮肤水分等方面显现出的一定功效,而由此衍生出的胶原蛋白产品,尤其受到广大女性消费者的青睐。然而,随着市场需求的日益增长,一些不良商家开始在利益的驱使下做出种种不良举动,严重误导了消费者。7月5日,中央电视台新闻频道,深入报道了近期我国胶原蛋白市场出现的种种乱象,并对目前市面上很多不良商家以普通胶原蛋白食品冒充保健品销售,以及肆意宣扬养颜、祛斑等美容功效的行为进行了披露,引发大众强烈关注。其中,在多个检测样品中仅一家产品合格,令不少消费者为之震惊。     

丝胶蛋白性能及美白防晒乳的研制

以水溶性天然丝胶蛋白为主要原料,辅以甘油、脂肪醇、维生素E油、乳化剂等,研制对紫外线有吸收作用的丝胶美白防晒乳.经理化指标和卫生指标测试,结果符合卫生部<化妆品卫生规范>(2007)和轻工行业标准规定:毒理试验,皮肤过敏、刺激性试验结果表明,该产品安全可靠,并获卫生部特殊用途化妆品批号.介绍了水溶性天然丝胶蛋白的提取及丝胶美白防晒乳的研制过程和检测结果.     

鸡精标准出台一年大部分企业并未采用

尽管中国鸡精行业标准颁布实施已有一年,但据了解,中国鸡精四大巨头中除了负责起草该标准的太太乐在执行该标准,其他的三大巨头尚未采用该标准。而据了解,目前市场上在售的约十几种鸡精品牌中仅有不超过5种品牌鸡精标注“符合中国鸡精行业标准”标志。在北京一家超市,货架上在售的9种鸡精品牌中只有2种品     

Ultrasonic Nebulizer Assisted LIBS: a Promising Metal Elements Detection Method for Aqueous Sample Analysis

A newly developed approach for trace metal elements detection for aqueous samples analysis is presented in this paper. The idea of this approach is to improve ablation efficiency by transforming the liquid sample into a dense cloud of droplets using an ultrasonic nebulizer. The resulting droplets are then subjected to analysis by laser induced breakdown spectroscopy (LIBS). A purpose-built ultrasonic nebulizer assisted LIBS (UN-LIBS) system has been applied to the analysis of aqueous samples at trace levels of concentration. Experimental investigations of solution samples were carried out with various dissolved trace metal elements (Mn, Zn, Cu, Pb, Fe, Mg and Na) using this approach. The characteristics of UN-LIBS signal of the elements were investigated regarding the lifetime and S/B ratio and the calibration curves for trace metal elements analyses. The obtained LODs are comparable or much better than the LODS of the reported signal enhancement approaches when the laser pulse energy was as low as 30 mJ. The good linearity of calibration curves and the low LODs shows the potential ability of this method for metal elements analysis application. The density of the electrons was calculated by measuring the Stark width of the line of Hα. The possible mechanism of the LIBS signal enhancement of this approach was briefly discussed.