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31.
Erratum to: J Syst Sci Syst Eng DOI: ./s--- The presentation of Table in the original version of this article contained a few typos. The corrected Table is given below. …… 《系统科学与系统工程学报(英文版)》2008,17(2):255-256
Erratum to: J Syst Sci Syst Eng
DOI: 10.1007/s11518-007-5058-2
The presentation of Table 2 in the original version of this article contained a few typos. The corrected Table 2 is given below. 相似文献
32.
对巨大灾难的管理(包括自然和人为的灾难)要获得高效、取得成功,决策者必须要及时获取相关信息。德国早年的一些大规模的灾难,例如2002年8月易北河的大洪水、1999年12月发生在德国南部的Lothar暴风雪,都显示了灾难管理部门只获取了部分的必需信息,在联邦政府和受灾地区的灾难反应部门间的通讯信息流也是极度不足。有鉴于此,2001年夏天德国内政部门决定建立“危机预防信息系统”(GermanEmergencyPlanningInformationSystem/简称deNIS)。在此基础上开发的denISⅡ的目标则是为市 相似文献
33.
C.D.Gómez-Esparza R.Peréz-Bustamante J.M.Alvarado-Orozco J.Mu?oz-Salda?a R.Martínez-Sánchez J.M.Olivares-Ramírez A.Duarte-Moller 《北京科技大学学报》2019,(5)
An AlCoCuCrFeNiTi high-entropy alloy(HEA) was prepared by mechanical alloying and sintering to study the effect of Ti addition to the widely studied AlCoCuCrFeNi system. The structural and microstructural characteristics were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), and transmission electron microscopy(TEM). The formation of four micrometric phases was detected: a Cu-rich phase with a face-centered cubic(fcc) structure, a body-centered cubic(bcc) solid solution with Cu-rich plate-like precipitates(fcc), an ordered bcc phase, and a tetragonal structure. The XRD patterns corroborate the presence of a mixture of bcc-, fcc-, and tetragonal-structured phases. The Vickers hardness of the alloy under study was more than twice that of the AlCoCuCrFeNi alloy. Nanoindentation tests were performed to evaluate the mechanical response of the individual phases to elucidate the relationship between chemical composition, crystal structure, and mechanical performance of the multiphase microstructure of the AlCoCuCrFeNiTi HEA. 相似文献
34.
Tumour biology: senescence in premalignant tumours 总被引:1,自引:0,他引:1
Collado M Gil J Efeyan A Guerra C Schuhmacher AJ Barradas M Benguría A Zaballos A Flores JM Barbacid M Beach D Serrano M 《Nature》2005,436(7051):642
Oncogene-induced senescence is a cellular response that may be crucial for protection against cancer development, but its investigation has so far been restricted to cultured cells that have been manipulated to overexpress an oncogene. Here we analyse tumours initiated by an endogenous oncogene, ras, and show that senescent cells exist in premalignant tumours but not in malignant ones. Senescence is therefore a defining feature of premalignant tumours that could prove valuable in the diagnosis and prognosis of cancer. 相似文献
35.
Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia 总被引:2,自引:0,他引:2
JE Vonk L Sánchez-García BE van Dongen V Alling D Kosmach A Charkin IP Semiletov OV Dudarev N Shakhova P Roos TI Eglinton A Andersson O Gustafsson 《Nature》2012,489(7414):137-140
The future trajectory of greenhouse gas concentrations depends on interactions between climate and the biogeosphere. Thawing of Arctic permafrost could release significant amounts of carbon into the atmosphere in this century. Ancient Ice Complex deposits outcropping along the ~7,000-kilometre-long coastline of the East Siberian Arctic Shelf (ESAS), and associated shallow subsea permafrost, are two large pools of permafrost carbon, yet their vulnerabilities towards thawing and decomposition are largely unknown. Recent Arctic warming is stronger than has been predicted by several degrees, and is particularly pronounced over the coastal ESAS region. There is thus a pressing need to improve our understanding of the links between permafrost carbon and climate in this relatively inaccessible region. Here we show that extensive release of carbon from these Ice Complex deposits dominates (57?±?2 per cent) the sedimentary carbon budget of the ESAS, the world’s largest continental shelf, overwhelming the marine and topsoil terrestrial components. Inverse modelling of the dual-carbon isotope composition of organic carbon accumulating in ESAS surface sediments, using Monte Carlo simulations to account for uncertainties, suggests that 44?±?10 teragrams of old carbon is activated annually from Ice Complex permafrost, an order of magnitude more than has been suggested by previous studies. We estimate that about two-thirds (66?±?16 per cent) of this old carbon escapes to the atmosphere as carbon dioxide, with the remainder being re-buried in shelf sediments. Thermal collapse and erosion of these carbon-rich Pleistocene coastline and seafloor deposits may accelerate with Arctic amplification of climate warming. 相似文献
36.
Peña PV Davrazou F Shi X Walter KL Verkhusha VV Gozani O Zhao R Kutateladze TG 《Nature》2006,442(7098):100-103
37.
自主导航系统是高超声速飞行器自主控制性能的关键因素.合成孔径雷达(SAR)系统作为高超声速飞行器的关键导航设备,其获取的SAR图像受高超飞行器影响存在严重噪声干扰.在分析KAZE特征检测算法的基础上,针对KAZE算法计算复杂度高的问题,引入Fast Explicit Diffusion算法,设计了快速非线性尺度空间构建方法,并在此基础上提出了改进KAZE特征检测算法和基于改进KAZE算法的惯导/SAR组合导航景象匹配算法.通过仿真验证表明,提出的改进KAZE特征算法在保留KAZE算法噪声鲁棒性的同时,有效降低了KAZE算法的复杂度,其计算效率与SIFT算法相当,位置误差估计精度优于SIFT算法. 相似文献
38.
微气泡减阻的数值模拟方法及尺寸效应 总被引:2,自引:0,他引:2
分别采用混合物模型、欧拉双流体模型和相群平衡模型对底部通气的二维平板微气泡减阻效果进行了模拟分析,探讨了气泡直径、喷气速度对微气泡减阻率的影响,并对其尺度效应进行研究.结果表明:减小气泡直径可以增加微气泡减阻率;在一定的范围内,减阻率随着喷气速度的增加而增大,但喷气速度过小或过大都将影响减阻效果;相群平衡模型比其他2种模型的数值模拟结果更接近于试验结果;由于物体尺寸增加所致的雷诺数增大在一定程度上会降低微气泡减阻率. 相似文献
39.
If H is abialgebra B is a left H-module algebra a left H-comodule coalgebra the smash productalgebra structure the smash coproduct coalgebra structure over BH can form abialgebra in certain conditions called biproduct denoted by BH.We present theformulas of quasitrangular structure of biproduct if it contains a quasitrangularstructure.We obtain the necessary sufficient conditions for such that it becomes aquasitriangular bialgebra.…… 《河南师范大学学报(自然科学版)》2004,32(2):120-120
If H is a bialgebra, B is a left H-module algebra and a left H-comodule coalgebra, the smash product algebra structure and the smash coproduct coalgebra [1]structure over BH can form a bialgebra in certain conditions [2],called biproduct and denoted by BH.We present the formulas of quasitrangular structure of biproduct if it contains a quasitrangular structure.We obtain the necessary and sufficient conditions for such that it becomes a quasitriangular bialgebra. 相似文献
40.
分形图像压缩的一种改进算法 总被引:1,自引:0,他引:1
针对分形图像压缩的缺点,基于分形图像压缩的基本原理,对匹配搜索之前定义域块的采样方式提出了一种基于主对角线的计算方式.该计算方式取代了传统的取平均的方法,简化了计算的复杂度.实验结果表明,该方法在时间和峰值信噪比(PSNR)两个方面都取得了良好的效果. 相似文献