Wi-Fi devices have limited battery life because of which conserving battery life is imperative. The 802.11 Wi-Fi standard provides power management feature that allows stations(STAs) to enter into sleep state to prese...Wi-Fi devices have limited battery life because of which conserving battery life is imperative. The 802.11 Wi-Fi standard provides power management feature that allows stations(STAs) to enter into sleep state to preserve energy without any frame losses. After the STA wakes up, it sends a null data or PS-Poll frame to retrieve frame(s) buffered by the access point(AP), if any during its sleep period. An attacker can launch a power save denial of service(PS-DoS) attack on the sleeping STA(s) by transmitting a spoofed null data or PS-Poll frame(s) to retrieve the buffered frame(s) of the sleeping STA(s) from the AP causing frame losses for the targeted STA(s). Current approaches to prevent or detect the PS-DoS attack require encryption,change in protocol or installation of proprietary hardware. These solutions suffer from expensive setup, maintenance, scalability and deployment issues. The PS-DoS attack does not differ in semantics or statistics under normal and attack circumstances.So signature and anomaly based intrusion detection system(IDS) are unfit to detect the PS-DoS attack. In this paper we propose a timed IDS based on real time discrete event system(RTDES) for detecting PS-DoS attack. The proposed DES based IDS overcomes the drawbacks of existing systems and detects the PS-DoS attack with high accuracy and detection rate. The correctness of the RTDES based IDS is proved by experimenting all possible attack scenarios.展开更多
认知语义学创始人Leonard Talmy(2000:117)提出了著名的语言两分法理论,认为:语言可以分为动词框架语言和卫星语框架语言,并进一步指出现代汉语属于卫星语框架语言。这一理论适用于整个宏事件所属的五类不同的框架事件,即运动事件、体...认知语义学创始人Leonard Talmy(2000:117)提出了著名的语言两分法理论,认为:语言可以分为动词框架语言和卫星语框架语言,并进一步指出现代汉语属于卫星语框架语言。这一理论适用于整个宏事件所属的五类不同的框架事件,即运动事件、体相事件、状态变化事件、关联事件和实现事件。关于现代汉语是否属于卫星语框架语言,学界有较大争论,目前大多数研究集中在运动事件。本文将研究视角转向状态变化事件(event of state change),旨在通过实证研究,从不同的视角探究现代汉语的词汇化模式,从而为现代汉语的准确定位提供更多依据。作为对状态变化事件的初步探索,文章集中研究存在性状态变化这一分类,通过图片描述的方式收集口语语料。语料分析发现存在性状态可以分为致使性和非致使性两种事件,致使性事件编码为卫星语框架结构,而非致使性事件中动词框架结构和卫星语框架结构呈现2:1的比例。本文最终结论认为:1)存在性状态变化事件呈现互补型模式;2)非致使性存在性状态变化事件的表征呈现两种框架结构并行合并模式。展开更多
Leonard Talmy在词汇化模式的研究中提出:语言可以划分为动词框架语言和卫星框架语言。在这种两分法中,现代汉语和英语一样都属于卫星框架语言。本文通过实证研究搜集了描述三类典型位移性运动事件的口语语料(火灾逃生、矿难升井、火山...Leonard Talmy在词汇化模式的研究中提出:语言可以划分为动词框架语言和卫星框架语言。在这种两分法中,现代汉语和英语一样都属于卫星框架语言。本文通过实证研究搜集了描述三类典型位移性运动事件的口语语料(火灾逃生、矿难升井、火山爆发),通过实证研究,对现代汉语路径语义要素的词汇化模式进行了分类研究。结果发现:本研究语料支持汉语是动词框架语言,不支持Talmy关于汉语是卫星框架语言的论断;研究不同的事件语域,会得出汉语是不同类型的结论。因此本文建议对现代汉语不同的语域做详尽的语言分析,寻找规律,不建议用卫星框架语言和动词框架语言这种过于笼统的概念给汉语定性。展开更多
基金supported by TATA Consultancy Servies(TCS)Research Fellowship Program,India
文摘Wi-Fi devices have limited battery life because of which conserving battery life is imperative. The 802.11 Wi-Fi standard provides power management feature that allows stations(STAs) to enter into sleep state to preserve energy without any frame losses. After the STA wakes up, it sends a null data or PS-Poll frame to retrieve frame(s) buffered by the access point(AP), if any during its sleep period. An attacker can launch a power save denial of service(PS-DoS) attack on the sleeping STA(s) by transmitting a spoofed null data or PS-Poll frame(s) to retrieve the buffered frame(s) of the sleeping STA(s) from the AP causing frame losses for the targeted STA(s). Current approaches to prevent or detect the PS-DoS attack require encryption,change in protocol or installation of proprietary hardware. These solutions suffer from expensive setup, maintenance, scalability and deployment issues. The PS-DoS attack does not differ in semantics or statistics under normal and attack circumstances.So signature and anomaly based intrusion detection system(IDS) are unfit to detect the PS-DoS attack. In this paper we propose a timed IDS based on real time discrete event system(RTDES) for detecting PS-DoS attack. The proposed DES based IDS overcomes the drawbacks of existing systems and detects the PS-DoS attack with high accuracy and detection rate. The correctness of the RTDES based IDS is proved by experimenting all possible attack scenarios.
文摘认知语义学创始人Leonard Talmy(2000:117)提出了著名的语言两分法理论,认为:语言可以分为动词框架语言和卫星语框架语言,并进一步指出现代汉语属于卫星语框架语言。这一理论适用于整个宏事件所属的五类不同的框架事件,即运动事件、体相事件、状态变化事件、关联事件和实现事件。关于现代汉语是否属于卫星语框架语言,学界有较大争论,目前大多数研究集中在运动事件。本文将研究视角转向状态变化事件(event of state change),旨在通过实证研究,从不同的视角探究现代汉语的词汇化模式,从而为现代汉语的准确定位提供更多依据。作为对状态变化事件的初步探索,文章集中研究存在性状态变化这一分类,通过图片描述的方式收集口语语料。语料分析发现存在性状态可以分为致使性和非致使性两种事件,致使性事件编码为卫星语框架结构,而非致使性事件中动词框架结构和卫星语框架结构呈现2:1的比例。本文最终结论认为:1)存在性状态变化事件呈现互补型模式;2)非致使性存在性状态变化事件的表征呈现两种框架结构并行合并模式。
