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1.
铅是一种易于沉积在骨骼中造成中毒的重金属。介绍了玉米汁的加工发展现状、铅的危害,论述了玉米汁饮料中铅的来源及检测方法。对最佳试验条件进行了优化,确定了氢化物发生原子荧光光谱法的最佳工作条件:灯电流80 mA,光电倍增管负高压-320 V,主气流量(载气)500 mL/min,屏蔽气流量(辅气)800 mL/min,泵速70 r/min,最后测定了长春市市售玉米汁中的铅的含量并进行了分析。  相似文献   

2.
Photoacoustic spectroscopy (PAS) is a highly sensitive gas analyzing method without the shortcoming of gas consumption, which can be used in transformer oil trace gases dissolved in on line monitoring. The photoacoustic signal is detected with a microphone, which is the only feature in gas concentration analysis. A portable and tunable experimental setup has been developed based on the photoacoustic spectroscopy fundamental. Through the photoacoustic signal stimulate mechanism analysis, this paper thoroughly discusses the influences of gas pressure, temperature, laser power, gas concentration, background gas, chopped frequency and the resonant frequency drift on the gas photoacoustic signal. The theoretical and experimental results supply reference and technical support for further improvements in oil gas photoacoustic spectroscopy of on-line monitoring system.  相似文献   

3.
The burning rate of hydrogen air pre mixture on meso scale is mainly determined by its chemical reaction rate. So a Laminar Finite Rate Model, the gas phase reaction mechanism for the combustion of hydrogen air mixture which consists of 19 reversible elementary reactions and the dynamic mesh method are adopted to simulate the combustion of hydrogen air mixture in a meso scale IC engine which operates a quasi gas power cycle under ultrahigh combustion load. The combustion of hydrogen air mixture on meso scale in the micro combustion chamber with moving boundary can be stable. The complete thermodynamic process of heat addition, internal energy increasing, and a boundary work output producing during expansion can be perfectly achieved in the closed combustion system of the meso scaled IC engine igniting the hydrogen air mixture by wire surface of high temperature. However, running parameters such as cycle period, initial pressure and fuel/air ratio have complex effects on the hydrogen air combustion of micro closed container with moving boundary.  相似文献   

4.
Office supplies and people may shade illuminance sensors installed on the table, thus the lighting dimming control system is not able to act correctly. Based on the illuminance ratio model, an index of illuminance-variation transfer ratio and an approach using sensors installed on wall instead of table are proposed. The point of this approach is to choose an appropriate illuminance-variation transfer ratio between vertical illuminance on wall and horizontal illuminance on table. The effects of the location of sensor and controlled lighting on the illuminance-variation transfer ratio are investigated by simulations and experiments. Two constraint conditions are presented for determining the location and number of sensors in an office or reading room. As an example, the proposed approach was applied to a lighting dimming control system in classroom, which confirmed the validity of the proposed approach.  相似文献   

5.
The conventional mechanical transmissions can be retro fitted to carry out the gearshift automatically.Their shifts must be detected by the sensors and controlled by the actuators.The method in detecting the shift with non contacted photoelectricity elements is proposed.For 5 speed gearboxes,two photoelectricity elements are used to detect three gear selecting positions,the other are used to two detect three gear shifting positions.The appropriate arrangement of switch inputs can make the nine shifts of a 5 speed gearbox be detected by four photoelectricity elements.Therefore the necessary switch numbers decrease,the necessary hardware is more simple and the control software is easy.The principle of shift detection and the program flow chart of shift control are given.  相似文献   

6.
After analyzing target recognition and tracking technique, a method of developing specifically target tacking system is proposed, which uses digital image manipulation to target recognition. Software and hardware design of intelligent vehicle are presented in detail. The system uses digital image manipulation technology to cognize the certain target through a pickup camera installed on the front of the intelligent vehicle. When the target is moving, singlechip receives the commands from the computer and then control the vehicle to trace target. The system can run by itself, regardless of artificial control. This design provides a platform for the research of Growing Machine Intelligence system.  相似文献   

7.
焦炉集气管压力是炼焦生产过程中重要的工艺参数,其值是否稳定,直接影响到煤气质量、焦炉寿命、焦炭质量和生产环境。针对焦炉集气管压力系统是一个强干扰、非线性和多变量耦合的复杂系统,采用LS-SVM辨识出焦炉集气管压力系统的逆系统模型,并将其串联在原系统之前,运用逆系统的方法将集气管压力系统解耦成2个相互独立的单输入单输出伪线性子系统。同时,对解耦后的系统采用非线性内模控制策略以保证系统的鲁棒性和稳定性。仿真和应用结果表明该控制策略的解耦控制效果较好,提高了系统的快速调节能力和跟踪精度,而且增强了系统的鲁棒性,可以保证焦炉集气管压力稳定在现场工艺要求的范围内。  相似文献   

8.
The treatment of wastewater is a complicated biological and chemical process, which can not be described precisely with a mathematical model. It is almost impossible to get a satisfactory control result when a traditional PID control method is adopted, for the parameters of the activated-sludge process are uncertain. The paper takes DO parameter controlling as an example, and proposes a human-simulated intelligent control strategy to reduce the fluctuation problem of DO parameter. Both the control rules and the structure of control system are presented. The simulation experiments shows that the control effect of activated-sludge process by HSIC is much better than PID control.  相似文献   

9.
随着科学技术的发展,农业的发展越来越趋于信息化、现代化,智慧农业是未来农业发展的必然趋势。温室控制系统是智慧设施农业的核心,是实现设施农业规模化发展、集约化生产的关键。本研究综述了温室控制相关研究进展,以期在今后的研究中起到一定的作用。温室控制系统自20世纪70年代发展至今越来越成熟,本研究对比了温室控制系统的控制算法、主控芯片、各种传感器,通过对近些年来包括控制系统在内的感知层、传输层和应用层等组成部分综述,并介绍了市面上比较主流的传感器、网络传输技术以及主控芯片,旨在为温室控制系统的设计提供一种可选择的方案,并对温室设施农业中存在的问题和未来的发展方向进行了分析和展望。  相似文献   

10.
氮气储粮技术在黄淮地区的应用   总被引:2,自引:1,他引:1  
粮食在保管过程中,往往遇到病虫害及微生物的侵扰,引起发热、霉变现象,粮食质量变差。采用传统的熏蒸技术,容易引起药剂残留,在生成食品后带来健康方面危害,对接触药剂人员造成身体伤害。氮气是一种高效无残留的气体,采用技术工艺在空气中即可获得,具有杀虫抑霉、无毒无污染[1]、供试粮食品质良好及使用方便等优点,深受广大用户好评,徐州直属库结合本库特点,在浅圆仓开展氮气储粮应用方面,取得了一定实践经验。  相似文献   

11.
Gas pressure distribution in landfills is of great importance to control hazards and improve recovery of landfill gas. An one-dimensional steady-state model and its solving approach are presented for gas pressure distribution in layered waste landfills. The model can be used to investigate the gas pressure distribution of the landfill with horizontal gas collection layers having specified pressure or flux. The influences of layered properties, horizontal permeable layer under final cover and horizontal gas collection layers and bottom leachate drainage systems dually serving as gas collection layers on gas pressure distribution are investigated. The results of parameter analyses using the presented model show that the assumption that homogenizations of gas generation rate and gas permeability through a landfill considerably overestimate gas pressure in landfill; horizontal permeable layer under final cover and horizontal gas collection layers can effectively reduce gas pressure in landfills; the bottom leachate drainage systems dually serving as gas collection layers can significantly reduce the gas pressure in the lower portion of landfills. The presented model provides a useful tool in the designing of landfill gas collection systems, such as, the positions and spacing of horizontal gas collection layers and pump section.  相似文献   

12.
微肥和有机肥对保山红土晒烟品质的影响   总被引:3,自引:1,他引:2  
为研究中微肥和有机肥对红土晒烟外观和内在品质的影响,探索提高和改善红土晒烟品质的有效途径,试验在基肥中加入有机肥,和大田生长期在叶面喷施中微量元素肥料,结果表明:施用有机肥的处理与对照相比,产量增加7.3%~20.9%,产值增加8.8%~25.3%,以厩肥+菜籽饼处理的效果最好;四个喷施微肥的处理其产量和产值均超过了喷清水的对照,其中产量增加6.7%~15.6%,产值增加6.8%~20.5%,以喷施镁肥的增幅最大。另外,喷施硼肥的处理与对照相比,烟碱降低了29.5%,总糖提高了20.9%;施用有机肥的处理,上部叶总糖、还原糖、总氮和蛋白质含量比对照增加,但烟碱变化不大。因此,红土晒烟生产上控制在适宜用量范围内使用有机肥是可行的。此外,施用有机肥还使红土晒烟的评吸质量获得提高。在团棵期和旺长期喷施硼肥,掌握在适宜用量的范围不仅可有效降低红土晒烟的烟碱含量,使烟丝化学成分更趋协调,而且改善了红土晒烟的香气品质,使整体内在质量获得提高。  相似文献   

13.
The CMOS image sensor has developed from passive pixel sensors and active pixel sensors to digital pixel sensors(DPS),which is the trend of image sensors.The advantage of DPS is that the imaging system can be integrated on a chip as imaging system-on-a-chip,decreasing the cost and power consumption,improving the imaging quality.The A/D conversion is the key component of the CMOS sensor.The authors analyze and compare the theories,performances and features of the chip level,column level and pixel level integrated ADC of the image sensor.They present the present and the future trend of the development about digital image sensor in the home and abroad.  相似文献   

14.
建立了茶叶中有机氯农药DDT残留量的大体积进样GC/MS选择离子分析方法。样品以丙酮提取,提取液以浓硫酸净化,采用DB—5MS石英毛细管柱,大体积进样,选择离子监测检测市售茶叶中DDT残留量,检出限比常规不分流检出限提高2个数量级,最低检测浓度约为0.8μg/kg。  相似文献   

15.
In order to realize early warning of coal and gas outbursts, and take timely emergency response, the technology of coal and gas outburst early warning and emergency response decision support is brought forward. The characteristics of abnormal gas outburst are specially analyzed, thus methods are given to monitor and identify the coal and gas outburst disaster. Combined with existing safety monitoring system in the mine, researches of such techniques are carried out as outburst gas content predicting, spread range forecasting and regions of power cutoff. Through those techniques, the Daping coal mine gas explosion disaster is retrieved. In the process of simulation, gas spreading early warning and related emergency response proposals can be issued before the gas arrive.  相似文献   

16.
有机微量元素化学结构稳定、生物效价高,可提高鸡的抗病、抗应激能力,减少环境污染。介绍了5种有机微量元素铜、铁、锰、锌、硒的生物学功能及有机微量元素在鸡生产上的应用情况。有机微量元素在吸收利用率、对鸡的生产性能和蛋品质改善等方面明显优于无机微量元素。但是由于微量元素产业的快速发展和相对滞后的生产水平之间的矛盾,导致有机微量元素在生产应用方面存在很多问题。本研究为找到有机微量元素在鸡生产上的最佳用量,减少微量元素对鸡产品和环境的污染,以及相关研究提供参考。  相似文献   

17.
Because of the high altitude of Qinghai, its air pressure is 0.77 atm which is lower than the atmospheric pressure. Therefore, an analysis is done for carbochlorination reaction of flyash for the extraction of aluminum in such an environment. The phase diagrams and predominance area diagram on chlorides are calculated and drawn and the equilibrium compositions of complex system composed of multi-components are simulated by Factsage software. Results show that, carbochlorination reaction converts Al2O3 and SiO2 which can not directly react with chlorine gas originally to chloride completely, and this demonstrates the thermodynamics feasibility of carbochlorination process. The ratio of FeCl3(Fe2Cl6) to FeCl2 changes with the amount of carbon and chlorine gas. The catalysts like Na2CO3, CaCO3 and B2O3 have some side effects in the aspect of thermodynamics such as consuming chlorine gas and carbon. The volatility of AlCl3(Al2Cl6) is affected by other chlorides. Compared with the normal pressure region, there are advantages and disadvantages to carbochlorination reaction under the pressure below the normal. The work provides thermodynamic data for the process.  相似文献   

18.
A DSP-based experimental system with real-time finger joint angle detection and prosthetic finger control is designed here. The prototype system is mainly composed of four parts: real-time finger posture detection, joint angle analysis, control pulse encode, and underactuated prosthetic hand with three individually active fingers, i.e. thumb, index finger and middle finger. The real-time finger joint movement is detected by acceleration sensor ADXL330, and the microprocessor DSPTMS320F2812 is used to collect the output of acceleration sensor and calculate angle changes of the finger joint instantaneously. Then, the angle changes are encoded to PWM pulse sequence to control the stepper motor, which drove the rotation of prosthetic finger joint. Preliminary tests are given to multi-finger motion detection and real-time prosthetic finger control, respectively. The experimental results show that the acceleration sensor ADXL330 can be used to reliably detect the gesture of finger movements, it can effectively drive flexion movement and extension movement of prosthetic finger, and the grip action can be completed with the coordination of thumb, index finger, and middle finger.  相似文献   

19.
王耘 《中国农学通报》2016,32(11):49-55
检测元件的实质是待测靶标的受体,在免疫分析、生物传感器等检测手段中已被广泛运用。目前新型检测元件越来越受到人们的关注,主要包括噬菌体展示多肽、亲和体、纳米抗体和分子印迹聚合物等,这些元件除了亲和力和特异性好,还可以通过直接合成或体外筛选获得,且可以固定于纳米材料表面,因此更利于在传感器中使用。文章概括了上述4种新型检测元件的特性以及其组建的传感器在食品检测领域中的热点应用方向,以期更加广泛地开发利用新型检测元件。  相似文献   

20.
用火焰原子吸收光谱法分别测定糯米糍荔枝皮、肉、核中钾(K)、镁(Mg)、铁(Fe)、锌(Zn)、锰(Mn)、铜(Cu)6种微量元素含量。结果表明,糯米糍荔枝中各元素含量丰富,而且荔枝皮中各元素的含量最高。  相似文献   

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