共查询到20条相似文献，搜索用时 15 毫秒
1.
A method of solving the problem of shoe leather lumen measurement in shoe CAD/CAM by industrial CT technology is introduced,X ray industrial CT technology is studied. The paper gives a rational scheme of system dispose. This scheme can be not only meet the need of shoe leather lumen measurement, but also achieve ordinary measurement. An uncomplicated and practicable movement control system are proposed also. This scheme achieves high precision of movement position without expensive direct current servo-control. A new simple method measurement is developed and accurate control of position in movement of detector data insert is achieved. The image resolving power can meet shoe leather lumen measurement. 相似文献
2.
In mechanical design and application, in order to calculate torsion angle and shear stresses of prismatic bars with seetorial cross-section undergoing extemal couples, the numerical method is presented. The torsion equation is nonhomogeneous partial differential equation. First, using the method of separation of variables, torsion stress function is acquired in polar coordinate. Then, the method of boundary collocation is improved to calculate the undetermined parameters. Finally,approximate numerical solutions of stress function and shear stresses in cross-section are obtained. It is given the several calculation results of shear stresses of prismatic bars with different vertex angles. These results show that the method has some precision and application feasibility in engineering design. The method of separation of variables is combinied with the method of boundary collocation simplified calculation process. 相似文献
3.
不同棱型大麦品种混种增产效果初探 总被引：1，自引：0，他引：1
为了探索不同棱型大麦品种混种的增产机理及效果,以保山市大面积推广的多棱品种保大麦14号、二棱品种82-1为材料,设5个处理,进行单种和混种比较试验,结果表明,混种能充分利用空间、利用光能,从而提高产量,产量比单种二棱矮秆品种增加139.5～719㎏/hm2,比单种多棱高秆品种增40.5～720㎏/hm2;产量构成因素中,有效穗与单种二棱品种(单种中有效穗最多)相近,穗实粒数比单种二棱矮秆品种增7.8～10.7粒,千粒重比单种多棱高秆品种增1.2～5.5g,同时,混种还能减轻倒伏;二棱品种82-1与多棱品种保大麦14号混种基本苗最佳比例为6:4(折合种子重量≈7:3)。 相似文献
4.
《Soil Technology》1989,2(3):221-241
A numerical method for determining the thermal conductivity of a soil in situ is proposed. It requires the measure of the temperature at three levels in the soil. From the knowledge of the boundary conditions (temperatures at the top and the bottom of the soil layer) and an estimation of the initial the mal profile, the temperature at the intermediate level can be calculated by integration of the monodimensional heat conduction equation with a numerical method (finite elements method). The boundary conditions are interpolated by the FOURIER series. The heat capacity is calculated according to the model of DE VRIES. The thermal conductivity is estimated by minimizing the residual sum of squares between calculated and measured temperatures at the intermediate level. The soil layer can be considered either homogeneous or stratified in two sub-layers. Using simulated temperature data, the optimal conditions of use of the method are defined and the sensitivity of the method to errors made on the measure of the temperature and on the position of the temperature probes is studied.In the case of an homogeneous soil layer, the method yields a good estimation of the thermal conductivity (error ≤1%) with a 4 hours period of estimation, whatever the position of the intermediate probe. The more precise estimation is obtained with an intermediate probe placed at the middle of the layer and with a high thermal amplitude. The method is not sensitive to errors made on temperature measures (biased or truncated measures) if the estimation is made on a period of 24 hours. It is highly sensitive to errors made on the position of the temperature probes.In the case of a stratified layer, the method allows to estimate the thermal conductivity of each sub-layer whatever the position of the intermediate probe if the period of estimation is at least 12 hours. The method is very sensitive to errors made on temperature measures (whatever the duration of the estimation period), on the position of the temperature probes and on the position of the limit between the two sub-layers. Therefore, its use for a stratified soil layer seems delicate. 相似文献
5.
为了探索江苏省洪泽湖农场土壤速效钾的空间分布规律,精确衡量其土壤速效钾的供应能力,通过网格取样方法、利用GPS定位取得该农场的180个耕层（0~20 cm）土壤样品,应用地统计学分析方法进行实验变差函数的计算和最适合模型的拟合,得出土壤速效钾最好的理论模型为球状模型,随后用普通克立格估值方法绘制了土壤速效钾的空间分布图。通过对不同阶数趋势的土壤速效钾克立格（Kriging）插值误差的综合比较,表明其趋势效应参数应选取二阶。克立格估值标准差（KSD）作为内插象素值的标准差,为提高速效钾的制图精度提供了有用的信息。应用地统计方法和GIS技术研究土壤养分的空间分布规律、衡量土壤养分的供应能力,其方法和结果对于在农业生产中合理施肥、探索发展精确农业、农业可持续发展等方面都有重要的参考价值。 相似文献
6.
The fuction and structure of the atrium are very complexity. If fire occurs,it will bring great loss. Forms of atrium and the characters of gas flow are analyzed, fire detectors are classified. Performance, applicability and the cause of wrong alarm of fire detector are compared comprehensively. According to the performance of detector, the shape of atrium and the character and possible danger of fire,a method of selecting fire detector to be applied to atrium is given. The validity of the method is explained clearly with an given example. 相似文献
7.
Numerical control last making machine is a machine that is used to process shoe last. A new principle of numerical control machining shoe last is put forward aiming at the deficiency of current carving last system. On the basis of the principle, the algorithm of cutter machining position during numerical controlled carving last is analyzed in detail. The complex problem of the calculation of cutter machining positiion is resolved by applying spherical milling cutter that is often used in machining free_curve surface today and taking account of practical situation of the shoe last_making machine. At the same time, the calculation of cutter machining position is realized by program using Visual C++6.0. As a result, the calculation time of cutter machining position is reduced greatly and the efficiency of design is improved. Moreover, the process of carving last is agile and precision of carving last is ensured. 相似文献
8.
为了解不同烟叶类型中碱性香味成分的差异,利用同时蒸馏萃取的前处理方法和配备氮—磷检测器的气相色谱仪,对碱性香味成分进行了分析鉴定;采用内标法对烟叶中的吡啶、2-甲基吡嗪、2,6-二甲基吡嗪、2-乙酰基吡啶等14种重要的碱性香味成分进行了定量分析。结果表明,分析方法的重复性好,前处理过程的回收率高,适用于烟叶中碱性香味成分的定性定量分析。 相似文献
9.
基质固相分散萃取-气相色谱法同时检测丹皮中有机氯和拟除虫菊酯农药残留的研究 总被引：1，自引：1，他引：0
采用基质固相分散萃取-气相色谱(MSPD-GC)技术,建立丹皮中有机氯和拟除虫菊酯农药多残留分析新方法。以回收率为指标,采用正交设计优化选择填料种类,样品与填料量的比例、淋洗液的极性。丹皮样品与中性氧化铝(m/m,1:2)充分研磨5 min后装入10 mL玻璃层析柱内,通过10 mL乙酸乙酯洗脱,11种农药在0.02、0.1、1 mg/kg 3个添加水平的平均回收率为77.69%~110.7%,相对标准偏差均低于11.6%,方法检出限在0.1~3.4 μg/kg范围。该方法可同时监测丹皮中有机氯、拟除虫菊酯类等农药的残留水平,方法简便。 相似文献
10.
该文首次利用高效液相色谱法时大白菜种子的水溶性蛋白质进行了分析,确定了适宜的色谱分析条件:选用径向加压型Nova-Pak C_(18)反相色谱柱(规格为8mm (?).d.×10cm length,填充颗粒为球形,直径4μm,Waters Co.)以甲醇水溶液进行洗脱,种子中各蛋白组分得到了比较好的分离。洗脱时采用混合梯度洗脱方式:0-20分钟,从9%甲醇水溶液(A)到35%甲醇 0.02%三氧乙酸(B)的线性梯度洗脱;20-45分钟,以B洗脱液进行等强度洗脱.流速均为0.8ml/min。洗脱后的各组分用紫外光/可见光检测器在280nm处进行监测。实验结果还表明:不同提取液对色谱分离的结果有一定的影响,用0.1%巯基乙醇水溶液提取时,色谱峰的分离效果较好,主要组分的色谱峰比较显著,因而比较适于大白菜种子的分析。 相似文献
11.
A new frequency synthesis method is presented in this paper. Its fundamental ideology is that for any frequency needed to be output,the controller sends a different group of dividing numbers to the feedback programmable divider of PLL by means of a special algorithm so as to make the interference frequency at the output of the phase detector and the frequency resolution indeqendent from each other. Therefore,high resolution and wide bandwidth are achieved simultaneously. 相似文献
12.
建立了一种操作简单、快速定性检测粒状口香糖和巧克力豆中的巴西棕榈蜡高温气相色谱分析法,标样溶液直接用三甲基硅烷(BSTFA)衍生,样品经超声加热充分提取后用BSTFA衍生,用氢火焰离子检测器(FID)直接检测,在检测的3种口香糖样品和2种巧克力豆样品中,均检测出巴西棕榈蜡相关成分,并对样品中的巴西棕榈蜡含量进行了粗略估算。 相似文献
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14.
Sun Renbo Wang Daiyu 《保鲜与加工》1988,(4)
In this paper, the solution of cylindrical bending problem for rectangular plates supported by elastic and tensile supports on particular deformation condition are derived from practical engineering problem. By examples, some considerable matters of analysing prismatic structures are suggested. The solutions are also studied when the tensions are to be determined. the results are simple and easy to be used. 相似文献
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16.
基于NC III和TTC设计的胚乳性状QTL区间作图方法 总被引：1，自引：1，他引：0
根据三倍体胚乳性状的遗传模型, 提出基于NC III以及TTC两种遗传设计的胚乳性状QTL作图新方法, 并通过计算机模拟数据, 对该方法的可行性和有效性进行了分析验证。模拟研究供试因素包括QTL遗传力、F2群体植株数和每家系混合样品测定的胚乳数。考察指标包括QTL的统计功效以及QTL位置和效应估计的准确度与精确度。结果表明, 2种设计均有较高的QTL统计功效, 在供试的大多数处理中, 即使QTL的遗传力只有5%, 其被发现能力也可达100%。两种设计均可有效区分胚乳QTL的各种遗传效应。基于TTC设计的胚乳QTL作图方法, 在QTL的统计功效、位置估计和效应估计上, 均优于NC III设计, 虽然这一优势随着QTL遗传力的提高以及样本容量的增大而有降低的趋势。 相似文献
17.
A method of constructing GPS-based positioning services system by means of JAVA technology is introduced in this paper. The position data, which are sent from GPS satellites, are received by GPS receiving terminal and are analyzed by mobile computing client developed on J2ME in accordance with the differential GPS algorithm. The client submits special position querying information to position server in way of wireless GPRS network. After computing and data querying, the server developed by J2EE returns results to the mobile device. Then, the mobile computing client displays the position map or carries out further processing. All of these form a highly precise location-based services system. 相似文献
18.
The general methods in reverse engineering cannot measure the inside of close parts. Traditional methods like Capture Geometrical Inside (CGI) would destroy the part. We used the industrial computer tomography (ICT) method to obtain accurate measurements of close parts. Based on the acquired computer tomography images, the size of an internal part was obtained through image measurement and subsequently edited, amended, and dimensioned in CAD software. First, the position and the pixel size of the circle were determined based on existence probability. Next, the actual size of one pixel was obtained based on the image size and the purview diameter. Finally, the actual circle size was calculated by multiplying the pixel size and the actual size of one pixel. A real part was measured using the method. The results show that the relative error of the measured circle radius and the actual size is less than 0.5% and the measuring time is several seconds. 相似文献
19.
In this paper the static stress distribution of closed valve during diastole under the peak across valve pressure difference is analyzed with nonlinear finite element method. We analyzed the three shapes i. e.,spherical,cylindrical and rotating paraboloid type valves, respectively as a result of computation, it is suggested that the maximum principal normal and shearing stress for rotating paraboloid type valve are smaller than those for the cylindrical and spherical type valves. It shows that there exist some similarities of the stress distribution among these three type valves. 相似文献
20.
GUAN Chun~ 《保鲜与加工》2004,(12):37-41
To control the complex powers emanating from a bus in power system, there are two solutions. The obvious solution is to equip each of the n lines radiating from the node with its own UPFC. The next evolution of the idea is to equip with a multi-terminal UPFC. First, the configuration and the principle of the Two-terminal UPFC (when n=2) are presented. In consideration of the existing shortages of output model-constructing method and topological model-constructing method for T-UPFC, a switching function mathematical model of this device is constructed by introducing the concept of switching function. It has more generality than the output and the topological model with the consideration of the internal switching character and the physical course of the T-UPFC. 相似文献