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51.
特征X射线能谱法测定Fe^+注入小麦种子的深度 总被引:5,自引:2,他引:3
用110keV Fe^+离子束垂直注入小麦种胚后,在扫描电子显微镜上沿种子纵沟剖面,在不同深度上测量Fe元素被激发出的特征X射线强度分布,结果表明分布呈指数衰减,与晶体中的热扩散分布相类似,并对此进行了讨论。 相似文献
52.
Bor -Yir Chen Wei -Hsiung Wu Jiann -Ruey Chen Chum -Sam Hong 《Journal of Materials Science》1995,30(9):2254-2256
The temperature dependence characteristics of hydrogenated amorphous silicon thin-film transistors were investigated. The results indicate that as the temperature was increased, the threshold voltage and the field-effect mobility were first increased, and then decreased, which may be controlled by different mechanisms at low and high temperatures. In addition, if the temperature was higher than 420 K, the Fermi level was promoted to the degenerate-like states, the current channel always existed due to the temperature effect, and the threshold voltage became negative. 相似文献
53.
Synchronization attacks like random cropping and time-scale modification are very challenging problems to audio watermarking techniques. To combat these attacks, a novel content-dependent localized robust audio watermarking scheme is proposed. The basic idea is to first select steady high-energy local regions that represent music edges like note attacks, transitions or drum sounds by using different methods, then embed the watermark in these regions. Such regions are of great importance to the understanding of music and will not be changed much for maintaining high auditory quality. In this way, the embedded watermark has the potential to escape all kinds of distortions. Experimental results show strong robustness against common audio signal processing, time-domain synchronization attacks, and most distortions introduced in Stirmark for Audio. 相似文献
54.
Stephen Shaoyi Liao Huai Qing Wang Qiu Dan Li Wei Yi Liu 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(3):660-671
This paper presents a new method for learning Bayesian networks from functional dependencies (FD) and third normal form (3NF) tables in relational databases. The method sets up a linkage between the theory of relational databases and probabilistic reasoning models, which is interesting and useful especially when data are incomplete and inaccurate. The effectiveness and practicability of the proposed method is demonstrated by its implementation in a mobile commerce system. 相似文献
55.
56.
本文用X射线研究了Cu-20Zn-6Al(wt%)合金中贝氏体结构的有序性,并与马氏体结构进行了比较,实验表明,从高温B2母相和低温L21母相生成的贝氏体中(115)和(205)衍射峰或(1210)和(2010)衍射峰是重叠的,对生成的贝氏体进行一段时间的保温或缓慢冷却处理,其衍射峰的特征并不改变,这与马氏体(115)和(205)衍射峰或(1210)和(2010)衍射峰的分离特性不相符合。说明贝氏体结构有序度与马氏体明显不同,它的形成不可能继承母相的有序度。 相似文献
58.
There are more than 660 thermal springs in West Yunnan Province, 30 of which are high-temperature hydrothermal systems with reservoir temperatures above 150°C.All thermal springs in West Yunnan are under the control of the tectonics, most of them being distributed at anticlinoria of metamorphic rocks and granites. This paper discusses the relationship between thermal areas and tectonics, the correlation between thermal springs in West Yunnan and North Thailand, and the geothermal prospects in West Yunnan. 相似文献
59.
60.
Distributed Denial-of-Service (DDoS) attacks pose a serious threat to Internet security. Most current research focuses on
detection and prevention methods on the victim server or source side. To date, there has been no work on defenses using valuable
information from the innocent client whose IP has been used in attacking packets. In this paper, we propose a novel cooperative
system for producing warning of a DDoS attack. The system consists of a client detector and a server detector. The client
detector is placed on the innocent client side and uses a Bloom filter-based detection scheme to generate accurate detection
results yet consumes minimal storage and computational resources. The server detector can actively assist the warning process
by sending requests to innocent hosts. Simulation results show that the cooperative technique presented in this paper can
yield accurate DDoS alarms at an early stage. We theoretically show the false alarm probability of the detection scheme, which
is insensitive to false alarms when using specially designed evaluation functions.
This work is partially supported by HK Polyu ICRG A-PF86 and CERG Polyu 5196/04E, and by the National Natural Science Foundation
of China under Grant No. 90104005. 相似文献