铸钢用呋喃树脂中氨氮含量的快速测定方法

介绍纳式试剂比色法测定呋喃树脂中氨氮含量的工作原理。用浓硫酸将树脂样品中的有机氮氧化为无机铵盐,并以30%过氧化氢催化,以加速样品消解速度,然后将纳式试剂与铵盐络合后通过测量吸光度计算出氨氮的含量。通过对不同含量的树脂样品进行测量试验,证明该方法具有较高的检测准确度和灵敏度,加标回收结果在96%~104%之间。     

微波消解-电感耦合等离子体质谱法测定铁矿石中的26种痕量元素

建立了一套完整的电感耦合等离子体质谱法测定铁矿石中26种痕量元素的检测分析方法。实验中,将微波消解与电感耦合等离子体质谱法相结合,优化了电感耦合等离子体质谱仪的仪器参数,利用基体匹配法和内标法校正基体效应。检出限、加标回收、精密度相关实验表明:该方法检出限在0.03～0.87μg/g之间;加标回收率在95～105%之间;精密度在0.1～3.0%之间。该方法简单、快速、高效,可满足目前市场上对铁矿石中杂质元素含量检测的需求。     

气相分子吸收光谱法测定奶粉中蛋白质的含量

建立了基于气相分子吸收光谱法测定奶粉中蛋白质(凯氏氮)含量的高灵敏分析方法。对方法的线性范围、检出限、精密度和加标回收率进行了研究,结果表明利用该方法测定奶粉中凯氏氮含量,线性相关系数良好,方法检出限分别可达到0.0191 mg/kg。加标回收率在96.35%～100.99%范围,相对标准偏差在0.49%～0.72%范围。该方法准确可靠,可以在奶粉中蛋白质检测领域推广应用。     

红外分光光度法测定处理后油气田含油污泥中石油类

建立了红外分光光度法测定油气田含油污泥中石油类的方法,并对方法中提取频率和时间、提取次数、硅酸镁吸附方式及填充高度、空白试验的制备进行优化。实验结果表明,方法检出限为0.02 mg/g,空白加标样品测定的精密度在2.2%~8.9%之间,加标回收率在92.5%~100%之间;实际样品测定相对标准偏差在2.4%~8.9%之间,加标回收率在88.2%~104%之间。本方法前处理操作简单,样品用量较少,测定结果的准确度和精密度较好,检出限低,可适用于处理后油气田含油污泥中石油类的准确测定。     

超高效液相色谱-四极杆/静电场轨道阱高分辨质谱快速筛查鱼和虾样品中200种药物残留

建立了超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法,快速筛查鱼和虾样品中200种药物残留。取均质后的鱼或虾样品,加入适量0.1 mol/L EDTA-Na₂溶液,分别用乙腈和乙酸乙酯超声提取,经Oasis PRiME HLB通过式固相萃取柱净化,以0.1%甲酸水溶液和0.1%甲酸-乙腈溶液为流动相,Thermo AccucoreaQ色谱柱(100 mm×2.1 mm×2.6 μm)分离;采用Full MS/dd-MS²模式采集数据,利用自建的包含化合物保留时间、母离子和子离子质荷比等信息的数据库定性,一级质谱全扫描母离子定量。结果表明,本方法的检出限为1~50 μg/kg,在不同的加标水平下,200种药物的加标回收率为30%~120%,精密度为5%~30%,其中,精密度在5%~15%、15%~20%和20%~30%的比例分别为70%、10%和20%,且精密度20%~30%主要分布于低加标水平样品。利用本方法对48个鱼和虾实际样品进行筛查,共定性确定9种药物,分别是乙氧喹啉、恩诺沙星、环丙沙星、氧氟沙星、诺氟沙星、甲氧苄啶、磺胺二甲基嘧啶、敌百虫和依维菌素。该方法前处理简单、可同时测定多种药物、检测效率高、筛查定性准确度高。     

微波消解-电感耦合等离子体质谱法测定铬铁合金中的10种痕量元素

将微波消解与电感耦合等离子体质谱法相结合,优化了铬铁合金溶解方法。优化电感耦合等离子体质谱仪的仪器参数,利用标准加入法校正基体效应。在此基础上,建立了一套电感耦合等离子体质谱法检测铬铁合金中砷、锡、锑、镉、汞、铅、镧、铈、铊、铋10种痕量元素的检测分析方法。检出限、加标回收、精密度相关实验表明:该方法检出限在0.04~0.3μg/L之间;加标回收率在85.6~114.1%%之间;精密度在1.4~3.5%之间。该方法简单、快速、高效,可满足铬铁合金市场上对杂质元素含量检测的需求。     

液液萃取-C18固相膜萃取-气相色谱/质谱联用测定地下水中半挥发性有机物

采用液液萃取法和C₁₈固相膜萃取法对水样进行前处理,利用气相色谱/质谱联用技术进行分析测定,通过回收率实验和精密度实验对两种前处理方法进行比较。在加标回收实验中，液液萃取法的加标回收率普遍低于65%，不符合US EPA标准（70%~130%），而C₁₈固相膜萃取法的加标回收率都在70%~120%之间，符合US EPA标准；在精密度实验中，液液萃取法的相对标准偏差在30%以内，而C₁₈固相膜萃取法的相对标准偏差均不超过20%，两者均符合US EPA标准（<30%），但是C₁₈固相膜萃取法的实验效果更好。从实验中得出，C₁₈固相膜萃取法是地下水样较好的前处理方法。利用所研究的方法分析了北京市某生活区的地下水样，在该水样中检出了63种有机化合物，包括1种酯类、1种醇类、2种酸类、2种酚类、2种氯代烃、25种苯系物、4种烯烃、14种烷烃和12种多环芳烃。     

茶水中铜含量分析方法研究

本文研究分光光度法测定茶水中铜含量的方法。在pH=3.92的缓冲溶液中,铜离子与间氯偶氮安替比林形成蓝色络合物,其λmax为624nm,铜离子含量在0~1.6μg/mL范围内符合朗伯-比耳定律,方法的表观摩尔吸光系数为4.0×104L/(mol·cm),相关系数r为0.9980,精密度(RSD)小于4.2%,检出限为0.047μg/mL,加标回收率在93%~103%之间,符合分析要求。     

氧弹燃烧-离子色谱法测定油基切削液中的卤素

建立了氧弹燃烧-离子色谱法测定油基切削液中卤素的分析方法。通过对氧弹燃烧装置条件优化,采用胶囊称取0.2g样品,充氧压力2.5 MPa,吸收液20mL,静置吸收时间20min。用离子色谱法测定吸收液中F-、Cl-、Br-的含量,结果表明,该方法定量检测限为5mg/kg^9mg/kg,在0.02mg/L^0.40mg/L线性范围良好,相关系数在0.9993~0.9996之间,精密度为3.6%~9.8%。不同浓度加标回收率在93.3%~104.0%之间,该方法快速、准确、回收率高,重复性好,能够满足对切削液质量控制的需求。     

植物油中角鲨烯的GC/MS分析

建立植物油中角鲨烯的GC/MS分析方法,植物油经KOH-甲醇法皂化和三氟化硼衍生,经HP-5MS毛细管柱分离,以二十四烷酸为内标,用GC/MS选择性离子监测对角鲨烯进行定量测定。方法在0.0625～2.00μg/mL范围内线性关系良好,相关系数r>0.9998;最低检测限为7.8ng/mL。日内精密度为1.63%~2.89%,日间精密度为1.70%~3.22%。加标平均回收率为89.58%～94.12%。用所建立的方法测定6种植物油中角鲨烯含量。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.