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121.
A cybernetics model of manufacturing execution system(MES CM) was proposed and studied from the viewpoint of cybernetics.Combining with the features of manufacturing system, the MES CM was modeled by"generalized modeling"method that is discussed in large-scale system theory.The mathematical model of MES CM was constructed by the generalized operator model, and the main characteristics of MES CM were analyzed. 相似文献
122.
通过工程设计对公路建设投资影响的分析,阐明了工程设计是影响建设投资的主要因素之一,并通过实例证明了合理选择设计方案和采用技术标准等办法是控制投资的一条有效途径,而合理选择设计方案和技术标准又受到各种因素的影响和限制,对影响合理选择设计方案的原因进行了具体分析,并就此提出了几点相应对策,供同行们参考. 相似文献
123.
A multi-try counter-meshing gears (CMG) discrimination device based on micro electromechani-cal system (MEMS) technology was designed for some specified information fields. The discrimination deviceconsists of two groups of metal CMG, two pawl/ratchet mechanisms, two driving micromotors and two re-setting micromotors, which make the CMG withdraw by raising the pawls. The energy-coupling element isa photoelectric sensor with a circular plate which is notched. Micromotor is fabricated using the ultravioletLiGA (UV-LiGA) fabrication process and precision mechanical engineering. The discrimination device has thefunction which can automatically reset, with the correct resetting code, it can be tried another times. 相似文献
124.
In order to analyze the failure data from repairable systems, the homogeneous Poisson process(HPP) is usually used. In general, HPP cannot be applied to analyze the entire life cycle of a complex, re-pairable system because the rate of occurrence of failures (ROCOF) of the system changes over time rather thanremains stable. However, from a practical point of view, it is always preferred to apply the simplest methodto address problems and to obtain useful practical results. Therefore, we attempted to use the HPP model toanalyze the failure data from real repairable systems. A graphic method and the Laplace test were also usedin the analysis. Results of numerical applications show that the HPP model may be a useful tool for the entirelife cycle of repairable systems. 相似文献
125.
Dynamic investigation on composite flexible multi-body system considering thermal effect 总被引:1,自引:0,他引:1
The dynamic performance of composite flexible multi-body system under the simultaneous action of thermal fields and driving
constraint is analyzed. Based on strain-displacement relation of the Mindlin plate theory which includes transverse shear
deformation, and considering thermal effect, variation equations of laminated plate are derived by the principle of virtual
work. The finite element method is used for discretization. According to kinematics constraint relation, dynamic equations
for spatial slider-crank system are established. Simulation results show that spatial deformation (torsion deformation) appears
in the multi-layered composite slider-crank mechanism which is simulated with planar motions. Furthermore, the influence of
coupling between thermal expansion and flexible deformations of non-symmetrical composite plates on the large overall motion
under the uniform temperature field is investigated. Finally, significant change in constraint force due to the spatial deformation
is shown. 相似文献
126.
Novel mesh technique and its application in the wind field simulation for flexible spatial structure
In this paper, novel mesh techniques are proposed for wind field simulation of flexible spatial structure. For mesh generation,
an interpolation strategy is presented to obtain a mesh system with variable density. Two spatial structure examples are used
to examine the efficiency and applicability of this technique. Then based on the structured mesh system generated by the technique,
the mesh nodal coordinates are updated to adapt the moving boundary conditions by means of the mapping interpolation functions
and some examples are given to verify the effectiveness. Furthermore, the constrained counterforce distribution technique
and projection interpolation strategy are developed to implement the data exchange on the interaction surface of wind and
structure. Finally, the computational accuracy is numerically validated. 相似文献
127.
Based on Navier-Stokes equation and renormalization group (RNG) onflow model, the 3D symmetrical impinging jet model of laser
cutting is established by adopting a taper nozzle and a convergence nozzle. Numerical simulation of gas flow in laser cutting
is used to investigate the effect of workpiece thickness on flow field of assist gas in cutting slot. The isolines of static
pressure as well as the distributions of static pressure and velocity are analyzed in details with different workpiece thickness,
and the trend of dynamics characteristics of gas jet is shown in the study. For taper nozzles and convergence nozzles, the
dynamic structure of assist gas being close to the lower surface of workpiece is exacerbated while the cutting quality and
cutting efficiency become worse with the increasing of workpiece thickness. The parallel degree between assist gas and the
axis of convergence nozzle is better than that of taper nozzle after the gas goes out of the nozzles. Two typical subsonic
nozzles are designed for the cutting experiment at the end of the paper. 相似文献
128.
To quantify mechanical effects of plantar fascia and ligaments on the arch structure, a 3D finite element model of the foot
was created to simulate the balanced standing posture. Four cases after individual releases of plantar fascia, spring ligament,
long and short plantar ligaments were simulated respectively to compare their consequences to the predictions of the intact
structure. It was founded that the foot arch didn’t collapse obviously after any individual release of these structures. As
plantar fascia was released, tensions of plantar ligaments were largely increased. Long and short plantar ligaments performed
mutual compensation functions. 相似文献
129.
目的 探讨不同抗原修复法对DA.1U大鼠肝组织内核受体检测结果的影响.方法 应用微波修复法、高压修复法、酶修复法和高压加酶修复法对DA.1U大鼠肝组织切片进行修复,然后进行免疫组化染色.结果 DA.1U大鼠肝组织内核受体LXR-α、LXR-β、PPAR-γ和FXR经高压抗原修复后,染色阳性强度较其他修复方法明显增强,而且定位较佳.结论 在核受体免疫组化染色中高压抗原修复法染色效果优于其他抗原修复法. 相似文献
130.
Mesh motion strategy is one of the key points in many fluid-structure interaction problems. One popular technique used to solve this problem is known as the spring analogy method. In this paper a new mesh update approach based on the spring analogy method is presented for the effective treatment of mesh moving boundary problems. The proposed mesh update technique is developed to avoid the generation of squashed invalid elements and maintain mesh quality by considering each element shape and grid scale to th... 相似文献