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41.
税企博弈模型的再研究 总被引:6,自引:1,他引:5
刘京娟 《数学的实践与认识》1998,(4)
本文以文[1]基础,在更一般条件下提出了税企博弈模型,得到新的骗税罚款系数公式.从理论上证明了税务机关对企业抽样检查与全面检查具有相同的经济效果.最后,给出建模应注意的几个问题. 相似文献
42.
Measurements on seven rigid PVC compounds were carried out with a slit rheometer working in combination with an injection moulding machine. Plastication of the compounds occurred in the screw of the plastication unit, which also forced the melt through the die with a controlled forward velocity. The rectangular slit had a length of 90 mm and a widthB of 20 mm. The heightH could be varied between 0.8 and 3.3 mm. Pressures and temperatures were recorded at several positions in and before the die. Measurements were carried out at shear rates from 10 to 2000 s–1.When the reduced volume output
was plotted against the wall shear stress
W
, only four compounds showed master curves independent ofH, which is indicative of wall adhesion. In the other cases this plot did not produce such a master curve, but the plot of the mean velocity
against
W
was independent ofH (slip curve). This indicated that slip flow prevailed with a slip velocityv
G
When, in the case of wall slip, the smooth inner surfaces of the die were replaced by surfaces with grooves perpendicular to the direction of flow, slip flow was prevented and the flow curves
were shifted to much higher values of
Wc
Above a critical value of the wall shear stress (
Wc
) at which slip flow began, the output became nearly independent of
W
. From the measurements made below
Wc
a vs.
relation for the shear flow could be derived, which was used to calculate the superimposed shear flow
. Exact values of the slip velocity were then given by
. Wall slip only occurred for compounds with a high shear viscosity, which corresponds to a high molecular weight (K-value).Dedicated to Professor H. Janeschitz-Kriegl on the occasion of his 60th birthday. 相似文献
43.
A new modular slit die with optical windows in two different positions and three pressure transducers flush-mounted along the wall was built and coupled to the exit of a twin-screw extruder. Thus, the birefringence and the pressure drop of polystyrene were monitored inline during extrusion. Two experimental procedures were tested: steady-state and cessation of extruder feeding. The latter proved to be very useful in the case of polystyrene since the ratio between the birefringence and the pressure drop can be quantified for a wide range of steady-state conditions with a single experiment. In fact, down to relatively lower values of pressure drop, the birefringence proved to be a function of shear stress at the wall only, depending neither on the initial feeding rate nor on the aspect ratio of the slit die, for W/h down to 5, at least. 相似文献
44.
A method to measure the stress field at the fiber tip in the fiber pull out test was proposed by using a digital gradient sensing technique. First, the principle of digital gradient sensing is introduced, and the non-contact optical system of digital gradient sensing developed. Then, a fiber reinforced composite model specimen, where a nail was inserted in epoxy resin to act as a fiber, was performed, and a pull out test was conducted on the specimen using the digital gradient sensing technique. Finally, the angular deflections contour at the fiber tip was obtained, and the stress intensity factor was extracted from the angular deflections. The results show that the stress intensity factor at the fiber tip extracted from the angular deflections agreed with the results calculated by the finite element method. 相似文献
45.
《Journal of separation science》2017,40(14):2941-2949
A novel hollow‐fiber liquid‐phase microextraction based on oil‐in‐salt was proposed and introduced for the simultaneous extraction and enrichment of the main active compounds of hesperidin, honokiol, shikonin, magnolol, emodin, and β,β′‐dimethylacrylshikonin in a formula of Zi‐Cao‐Cheng‐Qi decoction and the single herb, Fructus Aurantii Immaturus , Cortex Magnoliae Officinalis , Radix et Rhizoma , and Lithospermum erythrorhizon , composing the formula prior to their analysis by high‐performance liquid chromatography. The results obtained by the proposed procedure were compared with those obtained by conventional hollow‐fiber liquid‐phase microextraction, and the proposed procedure mechanism was described. In the procedure, a hollow‐fiber segment was first immersed in organic solvent to fill the solvent in the fiber lumen and wall pore, and then the fiber was again immersed into sodium chloride solution to cover a thin salt membrane on the fiber wall pore filling organic solvent. Under the optimum conditions, the enrichment factors of the analytes were 0.6–109.4, linearities were 0.002–12 μg/mL with r 2 ≥ 0.9950, detection limits were 0.6–12 ng/mL, respectively. The results showed that oil‐in‐salt hollow‐fiber liquid‐phase microextraction is a simple and effective sample pretreatment procedure and suitable for the simultaneous extraction and concentration of trace‐level active compounds in traditional Chinese medicine. 相似文献
46.
In this paper, the rheological properties of an extrudable cement-based paste are investigated by means of an original ram
extrusion apparatus (capillary rheometer). The experimental results indicate that a careful measurement of the die pressure
is necessary to obtain a realistic viscosity vs shear rate curve, as required in extrusion technology. In particular, it is
shown that the optimal test configuration is when the pressure measurement is made directly inside the rheometer die. By applying
this rheological methodology in steady-state conditions, it has been observed that the extrudable cement-based material here
evaluated obeys to a simple power–law equation, in the range of shear rates investigated, which are suitable for an industrial
extrusion process.
This paper was presented at the third Annual European Rheology Conference (AERC) held in Hersonissos, Crete, Greece, April
24–27, 2006. 相似文献
47.
Anna Rudo Hans‐Ullrich Siehl Klaus‐Peter Zeller Stefan Berger Dieter Sicker 《Chemie in Unserer Zeit》2015,49(6):372-384
Diosgenin as a sapogenin is the aglycone of the saponine dioscin. It is occuring in plants such as yam, from which it is isolated on industrial scale since the 1940ies. Plant diosgenin is a starting substance for the synthesis of human, i.e. animal, hormones and “the pill”, which as a hormonal contraception represents a revolution in the control of human sexuality. History, isolation and spectroscopy of this complex sapogenin are reported. This article extends the briskly discussed feature “50 years pill in Germany” (Streller & Roth, ChiuZ, 2011 [( 1 ) ]) by a particular compound example. It belongs to the series on isolation and spectroscopy of natural products in this journal. 相似文献
48.
49.
挤出平缝口模通常用于加工膜和片材,对产品厚度的一致性有很高要求。本文给出了结合聚合物成型模拟技术、设计灵敏度分析和数值优化技术的口模形状优化设计方法。以最小压力降为目标函数,口模出口处任意点的速率与出口已知速率相对误差的平方和小于容许误差为约束函数,口模形状参数为优化设计变量,给出了目标函数的表达式,推导了日标函数、约束函数对优化设计变量的灵敏度公式。利用灵敏度分析和基于梯度的优化算法即序列二次规划算法(SQP法)求解最优设计参数。通过算例表明,应用该法进行口模优化设计可以减小压力降和口模出口速率变化率。 相似文献
50.