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61.
高温纵向压印过程的有限元热力耦合分析 总被引:1,自引:0,他引:1
利用作者开发的用于模拟二维(包括平面变形和轴对称变形)金属热塑性成形过程的有限元分析系统S-FORGE,对转子钢(25Cr2Ni4MoV)方坯高温纵向压印实验过程进行模拟,给出了模拟结果,并与实验结果进行对比,说明了S-FORGE系统的有效性。 相似文献
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保硬主元算法的数值报告 总被引:7,自引:2,他引:5
保硬主元算法是线性规划基线算法的一种很好的实现形式.在一张基线表格中可以同时实现原始可行和对偶可行.大量的数值实验表明保硬主元算法有稳健的收敛过程,与原始单纯形法相比,问题的规模越大,保硬主元算法的相对迭代次数越少,相对解题时间越短 相似文献
64.
板料变形中两种摩擦模型的比较 总被引:3,自引:0,他引:3
本文应用刚塑性有限元方法,分别采用修正的常剪应力摩擦模型和库仑摩擦模型,对板料在半球形冲头下的拉胀变形和在平底圆柱冲头下的拉延变形过程进行计算,并上述两种摩擦模型的作用机制以及它们板料塑成形过程的影响进行了研究。通过分析、比较与实验验证,表明库仑模型比常剪应力模型更为适合板料成形过程模拟的摩擦描述。 相似文献
65.
LIUChunlin RUANYing GUANChunyun 《科学通报(英文版)》2004,49(24):2643-2644
β-ocimene, a kind of monoterpene, was found recently as a plant communication signal molecule. It has two isomeric forms in nature: cis-β-ocimene and trans-β-ocimene. According to recent reports, all investigated plants, such as corn, cotton, lima bean, potato, tobacco, arabidopsis, and Mediterranean pine, could release the chemical component β-ocimene after fed by arthropod herbivores, 相似文献
66.
RuanKe XiaDe-lin YanPu-liu 《武汉大学学报:自然科学英文版》2004,9(2):193-197
The global characteristics of a fingerprint image such as the ridge shape and ridge topology are often ignored in most automatic fingerprint verification system.In this paper,a new representative method based on B-Spline curve is proposed to address this problem.The resultant B-Spline curves can represent the global characteristics completely and the curves are analyzable and precise.An algorithm is also proposed to extract the curves from the fingerprint image.In addition to preserve the most information of the fingerprint image,the knot-points number of the B-Spline curve is reduced to minimum in this algorithm. At the same time,the influence of the fingerprint image noise is discussed.In the end,an example is given to demonstrate the effectiveness of the representation method. 相似文献
67.
MRS study on lentiform nucleus in idiopathic Parkinson‘s disease with unilateral symptoms 总被引:5,自引:0,他引:5
OBJECTIVE: To investigate changes in magnetic resonance spectroscopy (MRS) of lentiform nucleus during the early stage of Parkinson's disease. METHODS: Twenty-five patients with idiopathic Parkinson disease with unilateral symptoms (IPDUS) and 25 healthy volunteers were enrolled in this study. MRS of the lentiform nucleus in each patient was taken and then concentrations of N-acetylaspartate (NAA), Creatine (Cr) and Choline (Cho) were calculated. RESULTS: Compared to that in the control, NAA/ (Cho+Cr) was significantly lower in the lentiform nucleus contralateral to symptoms and even that in the ipsilateral side in IPDUS patients (all P<0.05); while there was no difference between the two sides in the healthy volunteer (P>0.05). The ratio of NAA/(Cho+Cr) ipsilateral to the sympatomatic side of the patient was also lower than that of the control (P<0.05). CONCLUSIONS: There might be some changes with MRS on the lentiform nucleus during the early stage of idiopathic Parkinson's disease with unilateral symptom. MRS may be one of the reliable methods for early or even sub-clinical diagnosis. 相似文献
68.
Vetter DE Li C Zhao L Contarino A Liberman MC Smith GW Marchuk Y Koob GF Heinemann SF Vale W Lee KF 《Nature genetics》2002,31(4):363-369
Urocortin is a member of the corticotropin-releasing hormone peptide family and is found in many discrete brain regions. The distinct expression pattern of urocortin suggests that it influences such behaviors as feeding, anxiety and auditory processing. To better define the physiological roles of urocortin, we have generated mice carrying a null mutation of the urocortin gene. Urocortin-deficient mice have normal basal feeding behavior and stress responses, but show heightened anxiety-like behaviors in the elevated plus maze and open-field tests. In addition, hearing is impaired in the mutant mice at the level of the inner ear, suggesting that urocortin is involved in the normal development of cochlear sensory-cell function. These results provide the first example of a function for any peptidergic system in hearing. 相似文献
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70.
为实现大运河动态监测和管理,根据空间信息科学和历史文化遗产保护理论,探讨了基于空间信息技术的京杭大运河历史文化环境保护方法流程和技术路线,研制了大运河历史文化环境保护支持系统,并实际应用于南水北调东线一期工程的大运河历史文化环境保护研究工作,产生了一系列专题研究成果。结果表明,空间信息技术可以为历史文化环境保护提供强有力的技术支持和可靠保障,可以为缓解大运河历史文化环境保护与南水北调工程建设的矛盾、为大运河申报世界文化遗产作出重要贡献。 相似文献