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981.
首先分析了辽河油田L46块的地质特征,然后分析和介绍了开发前的油藏工程,主要包括前期准备井的部署原则,实施要求,指出该块必须采用注水补充能量的开发方式进行开发,给出了合理的井冈井距、即合理井距为300m,采用正方形并网,确定了油井产能为平均单井产油10t/d,最后予测了年产原油6.6×104t/d,采油速度为2.20%.  相似文献   
982.
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   
983.
本文采用有限元法对正挤压凹模的应力状况进行了分析计算,根据计算结果,对BJ130汽车轮胎螺母终成形凹模进行了改进设计.实践证明,使用改进后的凹模结构,可使模具寿命提高五倍以上.  相似文献   
984.
用于语音识别的鲁棒自适应麦克风阵列算法   总被引:1,自引:0,他引:1  
对现实环境中存在的混响以及非平稳干扰语音信源等因素导致的算法性能下降,提出了一种用于语音识别的鲁棒旁瓣对消算法。讨论了旁瓣对消算法在自适应麦克风阵列中的应用,分析了算法在不同的混响条件下、不同的干扰源的噪声抑制能力。该算法通过分帧处理将输入信号划分为一系列短时平稳的信号片段。根据当前帧的信噪比决定自适应滤波器的权系数更新方式。采用一定的范数约束来限制自适应滤波器权系数的误调整。实验结果表明该麦克风阵列在混响的现实环境中能够有效抑制平稳噪声源和交叠谈话背景干扰,提高了语音识别器的抗噪性能。  相似文献   
985.
The expression of Arabidopsis PDF1.2 gene isregulated by jasmonic acid (JA) and ethylene (ET). It also has been well documented that GCC box is an element responsive to ET, however, the responsive mechanism of JA in such plant defense gene expression is unclear. In this paper, the authors define the essential cis-acting element in PDF1.2 promoter responsive to methyl jasmonate (MeJA) through fragment deletions and site-directed mutageneses combiningAgrobacterium-mediated transient reporter gene expression in tobacco leaves. Firstly, the MeJA inducible expression o fPDF1.2 was confirmed by using the upstream -1.86 kb fragment of PDFI.2 gene. Secondly, the upstream -300— -243 bp fragment of the promoter was evidenced to respond to MeJA. To further characterize this promoter region, three point mutations were introduced into the -300— -243 bp fragment of the promoter. This result showed that the mutation of GCC box abolished MeJA induction, whereas the mutations of the G box-like and the imperfect palindrome sequence did not significantly decrease MeJA inducible effect, indicating that GCC box in PDFI.2 is essential for MeJA induction. The sufficient responsiveness to MeJA of this GCC box was further investigated by 4xGCC fused upstream to the CaMV 35S minimal promoter. This result suggested that the fused promoter was able to activate reporter gene expression in response to MeJA. Thus these results indicate that the GCC box in PDFI.2 is an essential and sufficient element to confer MeJA induction.  相似文献   
986.
Elemental carbon?EC) is a C-rich, O-H-S-N-depleted substance that is necessarily produced in the process of combustion. Due to the logn-term use of fire by cave-inhabiting ape-men, considerable amounts of 揺lemen-tal carbon?would be necessarily left behind in the corre-sponding strata inside the cave. The sepaation of EC was effected by the chemical method and the contents of carbon were determined on an element analyser and a self-made measuring system. The concentration of Ec in the hearth,the exhibited ash samples collected from near the hearth un-earthed in the 1930s, and the three samples of accumulated material collected from the tenth bed are 43.74%, 1.77%,3.88%,1.87% and 1.11%,respectively; those of the equivalent samples from the tenth bed outside the cave and samples from the fourth and seventh beds are at least one order of magnitude lower than the former抯. The above re-sults show that the sampling location of the tenth bed may be close to the hearth. Sampling over a wider range may lead to the finding of a location where the concentrations of EC are corresponding to the maximum values of EC in the hearth. The determination and study of EC may provide new evi-dence for the use of fire by Peking Man.  相似文献   
987.
988.
Genesis of zircon and its constraints on interpretation of U-Pb age   总被引:242,自引:10,他引:232  
Zircon U-Pb dating is the most commonly used method for isotopic geochronology. However, it has been a difficult issue when relating zircon U-Pb ages to metamorphic conditions in complex metamorphic rocks. Much progress has been made in the past decade with respect to the genesis of zircon and its constraints on interpretation of U-Pb age. Three methods have been proposed to link zircon U-Pb age to metamorphic conditions: ( i ) internal structure; ( ii ) trace element feature; (iii) mineral inclusion composition. Magmatic zircon shows typical oscillatory zoning and/or sector zoning, whereas metamorphic zircon has internal structures such as no zoned, weakly zoned, cloudy zoned, sector zoned, planar zoned, and patched zoned ones. Zircons formed in different geological environments generally have characteristic internal structures. Magmatic zircons from different rock types have variable trace element abundances, with a general trend of increasing trace element abundances in zircons from ultramafic through mafic to granitic rocks. Zircons formed under different metamorphic conditions have different trace element characteristics that can be used to relate their formation to metamorphic conditions. It is an effective way to relate zircon growth to certain P-T conditions by studying the trace element partitioning between coexisting metamorphic zircon and garnet in high-grade metamorphic rocks containing both zircon and garnet. Primary mineral inclusions in zircon can also provide unambiguous constraints on its formation conditions. Therefore, interpretation of zircon U-Pb ages can be constrained by its internal structure, trace element composition, mineral inclusion and so on.  相似文献   
989.
基于定性映射的模式识别方法(Ⅱ)   总被引:7,自引:3,他引:4  
设MPα×β是(二维黑白图像)模式P所构成的α×β阶矩阵,若φ(MPα×β)=tPm,m=α×β,是MPα×β的特征向量抽取映射,则模式P的识别可转化为tPm的识别,并可用以向量tPm为基准的定性映射加以表示,当且仅当,抽取映射φ是可逆变换(或表示),且逆变换φ-1(tPm)=MPα×β是P的生成(或"涌现")映射.  相似文献   
990.
急倾斜煤层开采解放层防治冲击地压数值模拟   总被引:3,自引:0,他引:3  
采用反煤央等脆性材料破坏特征的五参数Wilianm-Warnke强度准则破坏模型,利用有限单元单元“处死”的功能真实模拟开挖过程,进行急倾斜煤层开采解放层防治冲击地压的数值模拟研究,揭示了急倾斜煤层开采解放层的煤岩层应力场、变形场等物理量的变化规律和解放范围以及解放程度,为急倾斜煤层开采解放层防治冲击地压制定较为合理的方案、安全技术措施等提供重要的依据和指导作用。  相似文献   
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