Building a highly available and intrusion tolerant database security and protection system (DSPS)

INTRODUCTIONHowtoprotectthedatabase ,thekernelre sourcesofinformationwarfare,isbecomingmoreandmoreimportantsincetherapiddevelopmentofcomputerandcommunicationtechnology .TheArtificialIntelligenceInstituteofZhejiangUni versityhasprototypedaDatabaseSecuritya…     

Mathematical Analysis of Energy Efficiency in IEEE 802.11 DCF

The standardized IEEE ,802. II distributed coordination function （ DCF） provides a contention-based distributed channel access mechanism for mobile stations to share the wireless medium. However, when stations are mobile or portable units, power consumption becomes a primary issue since terminals are usually battery driven. This paper proposes an analytical model that calculates the energy efficiency of both the basic and the RTS/CTS access mechanisms of the IEEE 802. II protocol. The model is validated with simulation results using NS-2 simulation package. The effects of the network size, the average packet length, the initial contention window and maximum backoff stages on the energy efficiency of both access mechanisms are also investigated. Results show that the basic scheme has low energy efficiency at large packet length and large network size, and depends strongly on the number of stations and the backoff procedure parameters. Conversely, the RTS/CTS mechanism provides higher energy efficiency when the network size is large, and is more robust to variations in the backoff procedure parameters.     

学习策略在英语教学中的地位和应用

近年来，学习策略已成了一个引人注目的研究领域。根据我们最近对学生的问卷调查，我们发现掌握好适合于自己的学习策略是提高学习效率，发展自主学习能力的保证。本从英语学习策略的基本理论出发，提出了在外语教学中，教师要重视对学生进行认知策略、记忆策略、元认知策略、情感策略和社交策略的培养。使学生用较少的“能源消耗”，来获取较多的知识。     

A novel method for mobile robot simultaneous localization and mapping

INTRODUCTION A key prerequisite for a truly autonomous robot is that it can simultaneously localize itself and accu-rately map its surroundings (Kortenkamp et al., 1998), which is known as Simultaneous Localization and Mapping (SLAM), which, when phrased as a state estimation problem, involves a variable number of dimensions. Murphy and Russell (2001) adopted Rao-Blackwellized particle filters (RBPFs) as an effective way for representing alternative hypotheses on robot paths and ass…     

认知突显视阈下英汉多义动词对比研究--基于语科的“run/跑”为例

动词表征事件,涉及到事件主体、方式、结果等因素,不同因素的突显是多义性产生的动因。基于认知语言学的图形背景以及运动事件理论,以英汉多义动词“run/跑”为例,两者都在共性突显运动目的、速度和结果方面延伸出了基本相同的义项;但是英语“run”在时间、位移、状态、路线,而汉语“跑”则在方式、方向方面进行个性突显,使两者有了不同的义项。同时由于英语“run”比汉语“跑”在突显时延伸出的语义更加具体,因而比汉语有更多的义项。     

风险认知与决策领域的研究现状分析

风险决策是指决策者在面临两个或两个以上不确定的决策后果,尤其是在面对伴有负面结果的可能性时,所产生的复杂心理过程.对个体风险知觉的探究主要包括风险认知与风险偏好两个方面.风险决策常常涉及多个不确定性的负面结果.因此,个体所知觉到的风险情景也不会是单一的,对动态决策模型的研究成为决策科学发展的一个重要方向.     

阮元教育思想探析

清代著名学者阮元,创办了新式书院诂经精舍和学海堂,旨在培养有"经世致用"、对社会有用的人才.书院提倡德才兼备;主张因材施教,自由探讨;强调实事求是,学以致用;学术研究和教学相结合;确立破旧立新、推举学长的教学体制.倡导了实践,培养了学生的实际能力.阮元的教育思想和实践对清末的教育界产生了深远的影响,为中国的教育事业做出了突出的贡献.     

EBF网络特征映射和恢复及其在鲁棒话者识别中的应用

The performance of speaker verification systems is often compromised under real-world environments. For example, variations in handset characteristics could cause severe performance degradation. This paper presents a novel method to overcome this problem by using a non-linear handset mapper. Under this method, a mapper is constructed by training an elliptical basis function network using distorted speech features as inputs and the corresponding clean features as the desired outputs. During feature recuperation, clean features are recovered by feeding the distorted features to the feature mapper. The recovered features are then presented to a speaker model as if they were derived from clean speech. Experimental evaluations based on 258 speakers of the TIMIT and NTIMIT corpuses suggest that the feature mappers improve the verification performance remarkably.     

5-溴水杨醛甘氨酸修饰碳糊电极测定微量Cu2+的研究

在pH=9.0 H3BO3-Na2B4O7缓冲体系中,以5-溴水杨醛甘氨酸修饰碳糊电极为工作电极,Cu2 于 120mV(vs.SCE)处产生一灵敏的吸附波,其二阶导数峰电流与Cu2 浓度在4.0×10-9~8.0×10-7mol.dm-3范围内呈良好的线性关系,相关系数为0.9964,检出限为6.0×10-10mol.dm-3(3倍信噪比)。应用该法测定发样中Cu2 的含量,结果令人满意。     

管理的个体分析

随着个体主体意识的回归，管理的个体分析作为西方实证主义管理的基础之一，将在我国的管理领域广泛应用。本从回顾西方管理领域关于个体分析的理论。进而考察我国管理个体分析的历史情况。分析我国转型期的社会关系、社会分层、“迟发展效果”等对于个体的影响；最后，提出我国现阶段借鉴、运用管理的个体分析应着重注意的三个方面：有区别地借鉴吸收西方管理思想中关于个体分析的理论研究；根据转型期的特殊国情，有针对性、分阶段地借鉴、运用管理的个体分析；以及重视个体与组织的互动关系，在管理中充分发挥组织的功能。