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91.
通过对高密度面波勘探和台阵地脉动勘探的频散分析算法的理论分析,推导出了2种勘探数据频散分析目标函数的统一表达式.根据该结果,用加权函数将2个目标函数结合起来,联合分析2种数据得到一条由高频到低频的完整的频散曲线;反演该频散曲线就可得到由地表到大深度的地下构造.将该方法应用于松江古照壁文物保护之地基勘查,为建立地震响应分析模型提供了由地表到40 m深处的横波速度构造.该方法是一种简便快速并兼顾浅层精度和勘探深度的工程地质调查方法. 相似文献
92.
面向全自动控制交通系统的车辆调度算法 总被引:1,自引:0,他引:1
结合遗传算法和贪婪算法的优点,提出了聚类贪婪遗传算法,构建了一个全自动控制交通系统的仿真系统;针对遗传算法、贪婪算法和聚类贪婪遗传算法分别进行实验,并比较其实验结果.结果表明:当系统趋于稳定时,聚类贪婪遗传算法能够提高叫车请求的平均响应时间,从而避免叫车请求饿死的情况;聚类贪婪遗传算法可用于全自动控制交通系统车辆的调度. 相似文献
93.
运用ANSYS软件对大矢高脊线式叉筒网壳结构进行系统的静力性能分析,详细研究了结构跨度S、矢高f、环向区域份数Kn、径向节点圈数nx对结构静力性能的影响;在此基础上对结构进行自振特性分析和地震响应分析。探讨了跨度、矢高对结构基频的影响规律,及结构环向区域份数、径向节点圈数对结构震后最大位移的影响规律。研究结果表明:大矢高脊线式叉筒网壳静力性能良好,矢高对结构静力性能影响不大,环向区域份数、径向节点圈数对结构静力性能影响较复杂;结构自振频率分布和振型有很强的规律性,结构基频对跨度较敏感;结构抗震性能优越,结构环向区域份数对结构震后最大位移影响较大。 相似文献
94.
针对川东高陡地质构造复杂,钻井中深井、超深井机械钻速低,建井周期长,钻井成本过高的问题,分析了川东地区钻井速度低的原因,介绍了岩石的各种性质,钻头选型依据以及如何评判钻头井下使用情况等方面的知识,阐述了合理使用钻头的方法,提出了在川东地区高陡构造地层中提高钻井速度的三种措施:(1) 采用以偏轴-钟摆钻具组合为主的钻井方式进行钻进;(2) 开展喷射钻井,促进机械钻速提高;(3) 开展水力加压器的应用。以期不断优化和强化钻进技术来提高钻井速度确保井身质量。 相似文献
95.
在天然气水合物二维开采模拟系统基础上,进行了水合物原位生成及分解过程的实验研究,探讨了温度、压力及电容的变化特性;开展了天然气水合物降压开采二维实验研究,得到了二维开采过程中各参数的动态变化规律,并对敏感因素进行了评价。在水合物合成过程中,随水合物饱和度的增加,水量的不断减少,电容量总体减小趋势明显。降压开采表明在二维平面上存在一定的压差与温差,其中温降随与开采井的距离增大而减小。产气过程分为流动阻力控制、分解速率控制以及残余气体采出三个部分,主要受分解速率和流动阻力共同影响。 相似文献
96.
辽中凹陷锦州区块东营组发育三角洲滑塌浊积扇、远岸水下扇和近岸水下扇等重力流沉积。在高分辨率层序地层划分和对比的基础上,通过区域沉积体系分析,探讨了各类水下重力流沉积的形成条件,建立了相应的发育模式,分析认为:物源系统、坡折类型和湖平面变化的耦合关系决定着沉积体的基本特征,包括类型、层序位置、发育部位和规模大小等。进一步研究表明,各类重力流沉积内部构成差异明显,坡折类型及组合样式对其控制作用明显,表现为:坡折组合的规模和复杂状况决定了砂体平面展布的分异状况;坡折带的类型和坡度决定着沟道体系的发育情况;坡折下方微地貌构建的次级坡折带控制着砂体的分配,尤其是优质砂体的富集位置。沟道化是断陷湖盆重力流沉积的一大特色,探讨了其有别于经典海相重力流相模式的原因。对岩性圈闭的勘探有一定的借鉴意义。 相似文献
97.
Chen Z Cheng K Walton Z Wang Y Ebi H Shimamura T Liu Y Tupper T Ouyang J Li J Gao P Woo MS Xu C Yanagita M Altabef A Wang S Lee C Nakada Y Peña CG Sun Y Franchetti Y Yao C Saur A Cameron MD Nishino M Hayes DN Wilkerson MD Roberts PJ Lee CB Bardeesy N Butaney M Chirieac LR Costa DB Jackman D Sharpless NE Castrillon DH Demetri GD Jänne PA Pandolfi PP Cantley LC Kung AL Engelman JA Wong KK 《Nature》2012,483(7391):613-617
Targeted therapies have demonstrated efficacy against specific subsets of molecularly defined cancers. Although most patients with lung cancer are stratified according to a single oncogenic driver, cancers harbouring identical activating genetic mutations show large variations in their responses to the same targeted therapy. The biology underlying this heterogeneity is not well understood, and the impact of co-existing genetic mutations, especially the loss of tumour suppressors, has not been fully explored. Here we use genetically engineered mouse models to conduct a 'co-clinical' trial that mirrors an ongoing human clinical trial in patients with KRAS-mutant lung cancers. This trial aims to determine if the MEK inhibitor selumetinib (AZD6244) increases the efficacy of docetaxel, a standard of care chemotherapy. Our studies demonstrate that concomitant loss of either p53 (also known as Tp53) or Lkb1 (also known as Stk11), two clinically relevant tumour suppressors, markedly impaired the response of Kras-mutant cancers to docetaxel monotherapy. We observed that the addition of selumetinib provided substantial benefit for mice with lung cancer caused by Kras and Kras and p53 mutations, but mice with Kras and Lkb1 mutations had primary resistance to this combination therapy. Pharmacodynamic studies, including positron-emission tomography (PET) and computed tomography (CT), identified biological markers in mice and patients that provide a rationale for the differential efficacy of these therapies in the different genotypes. These co-clinical results identify predictive genetic biomarkers that should be validated by interrogating samples from patients enrolled on the concurrent clinical trial. These studies also highlight the rationale for synchronous co-clinical trials, not only to anticipate the results of ongoing human clinical trials, but also to generate clinically relevant hypotheses that can inform the analysis and design of human studies. 相似文献
98.
Chen J Badioli M Alonso-González P Thongrattanasiri S Huth F Osmond J Spasenović M Centeno A Pesquera A Godignon P Elorza AZ Camara N García de Abajo FJ Hillenbrand R Koppens FH 《Nature》2012,487(7405):77-81
The ability to manipulate optical fields and the energy flow of light is central to modern information and communication technologies, as well as quantum information processing schemes. However, because photons do not possess charge, a way of controlling them efficiently by electrical means has so far proved elusive. A promising way to achieve electric control of light could be through plasmon polaritons—coupled excitations of photons and charge carriers—in graphene. In this two-dimensional sheet of carbon atoms, it is expected that plasmon polaritons and their associated optical fields can readily be tuned electrically by varying the graphene carrier density. Although evidence of optical graphene plasmon resonances has recently been obtained spectroscopically, no experiments so far have directly resolved propagating plasmons in real space. Here we launch and detect propagating optical plasmons in tapered graphene nanostructures using near-field scattering microscopy with infrared excitation light. We provide real-space images of plasmon fields, and find that the extracted plasmon wavelength is very short—more than 40 times smaller than the wavelength of illumination. We exploit this strong optical field confinement to turn a graphene nanostructure into a tunable resonant plasmonic cavity with extremely small mode volume. The cavity resonance is controlled in situ by gating the graphene, and in particular, complete switching on and off of the plasmon modes is demonstrated, thus paving the way towards graphene-based optical transistors. This successful alliance between nanoelectronics and nano-optics enables the development of active subwavelength-scale optics and a plethora of nano-optoelectronic devices and functionalities, such as tunable metamaterials, nanoscale optical processing, and strongly enhanced light–matter interactions for quantum devices and biosensing applications. 相似文献
99.
100.
“发动机原理”课程中的均质充量压燃燃烧涉及大量化学动力学机理,学生理解较为困难,运用Chemkin软件搭建发动机均质充量压燃燃烧的仿真实验模型,通过修改相应参数,得到不同初始条件下的放热率、缸内温度、缸内压力等仿真结果,针对仿真结果进行分组讨论,得到相应结论,并将燃料扩展到天然气,分析参数变化对天然气发动机均质充量压燃燃烧的影响,激发了学生的兴趣,加深了学生对教学内容的理解。 相似文献