A novel technique called physical frame time-slot switching （PFTS） is discussed and its technical and application aspects are analyzed. The format of the ethernet media access control （MAC） frame is borrowed in de...A novel technique called physical frame time-slot switching （PFTS） is discussed and its technical and application aspects are analyzed. The format of the ethernet media access control （MAC） frame is borrowed in defining the physical frame for PFTS and the transmission time for the maximum size of the MAC frame is defined as a physical frame time-slot （PFT）. Consequently, user data can be fed into PFTS and switched in a single layer sub-network in an asynchronous mode.展开更多
This paper presents an option for modern dynamic terrestrial reference system realization in Uzbekistan for user needs. An additive model is explored to predict patterns of time series and investigate means of constru...This paper presents an option for modern dynamic terrestrial reference system realization in Uzbekistan for user needs. An additive model is explored to predict patterns of time series and investigate means of constructing forecast time series models in the future. The main components(trend, periodical, and irregular) of the KIUB(DORIS) and KIT3, TASH, MADK, and MTAL(GNSS) international stations coordinate time series were investigated. It was shown that seasonal nonlinear trends occurred both in the height(U) component of all stations and the east(E) component of high mountainous stations such as MTAL and MADK. The seasonal periodical portion of the time series determined from the additive model has a complicated pattern for all sites and can be explained as both hydrological signals in the region and improvement of observational quality. Amplitudes of the best-fitting sinusoids in the North component ranged between 1.73 and 8.76 mm; the East component ranged between 0.82 and 11.92 mm; and the Up component ranged between 3.11 and 40.81 mm. Regression analysis of the irregular portion of the height component of the two techniques at the Kitab station using tropospheric parameters(pressure and temperature) was confirmed as only 57% of the stochastic portion of the time series.展开更多
In Newton’s classical physics, space and time are treated as absolute quantities. Space and time are treated as independent quantities and can be discussed sepa-rately. With his theory of relativity, Einstein proved ...In Newton’s classical physics, space and time are treated as absolute quantities. Space and time are treated as independent quantities and can be discussed sepa-rately. With his theory of relativity, Einstein proved that space and time are de-pendent and must be treated inseparably. Minkowski adopted a four-dimensional space-time frame and indirectly revealed the dependency of space and time by adding a constraint for an event interval. Since space and time are inseparable, a three-dimensional space-time frame can be constructed by embedding time into space to directly show the interdependency of space and time. The formula for time dilation, length contraction, and the Lorenz transformation can be derived from graphs utilizing this new frame. The proposed three-dimensional space-time frame is an alternate frame that can be used to describe motions of objects, and it may improve teaching and learning Special Relativity and provide additional insights into space and time.展开更多
目的实时渲染图形程序(如游戏、虚拟现实等)对高分辨率和高刷新率的要求越来越高,因此,针对渲染图像的实时超分辨率技术在实时渲染中非常必要。然而,现有的视频超分算法和实时渲染处于不同的数据处理管线之中,这导致其难以直接应用到实...目的实时渲染图形程序(如游戏、虚拟现实等)对高分辨率和高刷新率的要求越来越高,因此,针对渲染图像的实时超分辨率技术在实时渲染中非常必要。然而,现有的视频超分算法和实时渲染处于不同的数据处理管线之中,这导致其难以直接应用到实时渲染管线里。方法对此,提出了一个基于帧循环结构的实时神经超采样方法。充分利用实时渲染管线中生成的低分辨场景几何数据,以提升超采样网络对于三维空间信息的感知力;将帧循环框架结合到超采样方法中,通过引入先前帧重建结果的特征来改善当前帧的重建结果,从而实现时间尺度上的稳定性;将重加权网络和注意力网络置于特征提取模块中,以提升提取到的特征的有效性。此外,本文还提出了一个面向神经超采样的实时渲染流程,该流程能够将超采样网络部署至图形计算管线之上,并与实时渲染管线相结合。结果与同样能够实时且效果较好的基准方法面向实时渲染的神经超采样(neural super-sampling for real-time rendering,NSRR)比较,本文方法在速度少许提升的前提下,图像质量指标峰值信噪比(peak signal to noise ratio,PSNR)平均提升了0.4 dB,并在部署到实时渲染管线后,通过轻量化裁剪继续保持实时性且部分场景效果仍然优于非实时的部署后NSRR;在网络模块的消融实验中也证明了各个子模块对于神经超采样任务的有效性。结论本文提出的神经超采样网络模型与搭建的神经超采样渲染流程,在取得更好效果的同时具有一定的实用价值。展开更多
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
基金Supported by National Natural Science Foundation of China (No. 60372065)
文摘A novel technique called physical frame time-slot switching （PFTS） is discussed and its technical and application aspects are analyzed. The format of the ethernet media access control （MAC） frame is borrowed in defining the physical frame for PFTS and the transmission time for the maximum size of the MAC frame is defined as a physical frame time-slot （PFT）. Consequently, user data can be fed into PFTS and switched in a single layer sub-network in an asynchronous mode.
基金funded by the research-applied project of the Astronomical Institute of Uzbekistan (FA-A5-F014)
文摘This paper presents an option for modern dynamic terrestrial reference system realization in Uzbekistan for user needs. An additive model is explored to predict patterns of time series and investigate means of constructing forecast time series models in the future. The main components(trend, periodical, and irregular) of the KIUB(DORIS) and KIT3, TASH, MADK, and MTAL(GNSS) international stations coordinate time series were investigated. It was shown that seasonal nonlinear trends occurred both in the height(U) component of all stations and the east(E) component of high mountainous stations such as MTAL and MADK. The seasonal periodical portion of the time series determined from the additive model has a complicated pattern for all sites and can be explained as both hydrological signals in the region and improvement of observational quality. Amplitudes of the best-fitting sinusoids in the North component ranged between 1.73 and 8.76 mm; the East component ranged between 0.82 and 11.92 mm; and the Up component ranged between 3.11 and 40.81 mm. Regression analysis of the irregular portion of the height component of the two techniques at the Kitab station using tropospheric parameters(pressure and temperature) was confirmed as only 57% of the stochastic portion of the time series.
文摘In Newton’s classical physics, space and time are treated as absolute quantities. Space and time are treated as independent quantities and can be discussed sepa-rately. With his theory of relativity, Einstein proved that space and time are de-pendent and must be treated inseparably. Minkowski adopted a four-dimensional space-time frame and indirectly revealed the dependency of space and time by adding a constraint for an event interval. Since space and time are inseparable, a three-dimensional space-time frame can be constructed by embedding time into space to directly show the interdependency of space and time. The formula for time dilation, length contraction, and the Lorenz transformation can be derived from graphs utilizing this new frame. The proposed three-dimensional space-time frame is an alternate frame that can be used to describe motions of objects, and it may improve teaching and learning Special Relativity and provide additional insights into space and time.
文摘目的实时渲染图形程序(如游戏、虚拟现实等)对高分辨率和高刷新率的要求越来越高,因此,针对渲染图像的实时超分辨率技术在实时渲染中非常必要。然而,现有的视频超分算法和实时渲染处于不同的数据处理管线之中,这导致其难以直接应用到实时渲染管线里。方法对此,提出了一个基于帧循环结构的实时神经超采样方法。充分利用实时渲染管线中生成的低分辨场景几何数据,以提升超采样网络对于三维空间信息的感知力;将帧循环框架结合到超采样方法中,通过引入先前帧重建结果的特征来改善当前帧的重建结果,从而实现时间尺度上的稳定性;将重加权网络和注意力网络置于特征提取模块中,以提升提取到的特征的有效性。此外,本文还提出了一个面向神经超采样的实时渲染流程,该流程能够将超采样网络部署至图形计算管线之上,并与实时渲染管线相结合。结果与同样能够实时且效果较好的基准方法面向实时渲染的神经超采样(neural super-sampling for real-time rendering,NSRR)比较,本文方法在速度少许提升的前提下,图像质量指标峰值信噪比(peak signal to noise ratio,PSNR)平均提升了0.4 dB,并在部署到实时渲染管线后,通过轻量化裁剪继续保持实时性且部分场景效果仍然优于非实时的部署后NSRR;在网络模块的消融实验中也证明了各个子模块对于神经超采样任务的有效性。结论本文提出的神经超采样网络模型与搭建的神经超采样渲染流程,在取得更好效果的同时具有一定的实用价值。
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.
