The backward-facing step is a critical problem existing in many engineering and industrial applications.In this study,a semi-porous baffle(the root of the baffle is a porous medium and the tip is solid) is placed behi...The backward-facing step is a critical problem existing in many engineering and industrial applications.In this study,a semi-porous baffle(the root of the baffle is a porous medium and the tip is solid) is placed behind the step.The effects of the length of the porous part,and the baffle location on the energy transfer and pressure drop are studied in different Reynolds numbers(Re=100,200,300,400,500).The effect of the Darcy number of the porous medium on the aforementioned parameters is also investigated.Both the local maximum and average relative Nusselt numbers(divided by the Nusselt of the base case with no baffle at the same Reynolds) and relative pressure drop(calculated as the relative Nusselt number) are reported.The results show that by adoption of the proper length of the porous medium,the average relative and maximum local Nusselt numbers could be enhanced by 20% and 90%,respectively.Low permeable porous media give better energy transfer.For example,porous media with Da=10^(-5) give 30% better maximum local Nusselt number and about 7% higher average Nusselt number with respect to the same case with Da=10^(-2).展开更多
The Acoustic Sodar is widely used in the probe of the atmospheric boundary layer. We will use the Phase Locked Tracking Filter (PLTF) as the total program to measure the Doppler frequency deviation signal f_d of rando...The Acoustic Sodar is widely used in the probe of the atmospheric boundary layer. We will use the Phase Locked Tracking Filter (PLTF) as the total program to measure the Doppler frequency deviation signal f_d of random weak signal under the condition of an interference of strong noise and also we will use the transformation method of展开更多
To reduce decoding delay of a communication scheme which is backward-decoding-based and achievable Chong Motani-Garg capacity bounds, a novel forward-sliding-window decoding-based communication scheme is proposed. In ...To reduce decoding delay of a communication scheme which is backward-decoding-based and achievable Chong Motani-Garg capacity bounds, a novel forward-sliding-window decoding-based communication scheme is proposed. In this scheme, if w = （w1, w2） is the message to be sent in block b, the relay will decode message w1 and generate a new message z at the end of block b, and the receiver will decode message w1 at the end of block b ＋ 1 and decode message z and w2 at the end of block b ＋ 2. Analysis results show that this new communication scheme can achieve the same Chong-Motani-Garg bounds and the decoding delay is only two blocks which is much shorter than that of backward decoding. Therefore, Chong-Motani-Garg bounds can be achieved by a forward decoding-based communication scheme with short decoding delay.展开更多
A design method of a negative refractive index for free surface water waves in deep water is presented. To obtain a condition of a negative index, an analogy between water waves in a water channel and electric waves i...A design method of a negative refractive index for free surface water waves in deep water is presented. To obtain a condition of a negative index, an analogy between water waves in a water channel and electric waves in an electric circuit is employed. An analytical solution of waves around a periodic array of rectangular columns is obtained by a circuit analysis. Attention is not focused on columns but a space among columns, and then the space is regarded as the water channel. Therefore, the circuit analysis can be applied to water waves. One channel is treated as a unit structure and a number of channels are periodically cascaded as a network. The negative refraction and backward waves by a network of the water channels are shown. Since the negative refraction might occur even around simple periodic structures, it is meaningful to understand wave phenomenon around offshore structures and develop innovative technology.展开更多
安胜安全操作系统是自主研制的基于 Linux 的高安全等级安全操作系统,包括安全内核,安全架构与安全模型.总结了对该系统进行的隐蔽通道分析方法,首次报道基于 Linux 内核开发的安全操作系统的隐蔽通道分析结果.应用新型的“回溯方法”...安胜安全操作系统是自主研制的基于 Linux 的高安全等级安全操作系统,包括安全内核,安全架构与安全模型.总结了对该系统进行的隐蔽通道分析方法,首次报道基于 Linux 内核开发的安全操作系统的隐蔽通道分析结果.应用新型的“回溯方法”发现了某些新的隐蔽通道.对被标识的隐蔽通道,准确地计算了它们的带宽,并进行了适当的隐蔽通道处理.展开更多
文摘The backward-facing step is a critical problem existing in many engineering and industrial applications.In this study,a semi-porous baffle(the root of the baffle is a porous medium and the tip is solid) is placed behind the step.The effects of the length of the porous part,and the baffle location on the energy transfer and pressure drop are studied in different Reynolds numbers(Re=100,200,300,400,500).The effect of the Darcy number of the porous medium on the aforementioned parameters is also investigated.Both the local maximum and average relative Nusselt numbers(divided by the Nusselt of the base case with no baffle at the same Reynolds) and relative pressure drop(calculated as the relative Nusselt number) are reported.The results show that by adoption of the proper length of the porous medium,the average relative and maximum local Nusselt numbers could be enhanced by 20% and 90%,respectively.Low permeable porous media give better energy transfer.For example,porous media with Da=10^(-5) give 30% better maximum local Nusselt number and about 7% higher average Nusselt number with respect to the same case with Da=10^(-2).
文摘The Acoustic Sodar is widely used in the probe of the atmospheric boundary layer. We will use the Phase Locked Tracking Filter (PLTF) as the total program to measure the Doppler frequency deviation signal f_d of random weak signal under the condition of an interference of strong noise and also we will use the transformation method of
基金The Free Research Fund of National Mobile Communi-cations Research Laboratory of Southeast University(No.2008B06)the Na-tional Basic Research Program of China (973 Program)(No.2007CB310603)
文摘To reduce decoding delay of a communication scheme which is backward-decoding-based and achievable Chong Motani-Garg capacity bounds, a novel forward-sliding-window decoding-based communication scheme is proposed. In this scheme, if w = （w1, w2） is the message to be sent in block b, the relay will decode message w1 and generate a new message z at the end of block b, and the receiver will decode message w1 at the end of block b ＋ 1 and decode message z and w2 at the end of block b ＋ 2. Analysis results show that this new communication scheme can achieve the same Chong-Motani-Garg bounds and the decoding delay is only two blocks which is much shorter than that of backward decoding. Therefore, Chong-Motani-Garg bounds can be achieved by a forward decoding-based communication scheme with short decoding delay.
文摘A design method of a negative refractive index for free surface water waves in deep water is presented. To obtain a condition of a negative index, an analogy between water waves in a water channel and electric waves in an electric circuit is employed. An analytical solution of waves around a periodic array of rectangular columns is obtained by a circuit analysis. Attention is not focused on columns but a space among columns, and then the space is regarded as the water channel. Therefore, the circuit analysis can be applied to water waves. One channel is treated as a unit structure and a number of channels are periodically cascaded as a network. The negative refraction and backward waves by a network of the water channels are shown. Since the negative refraction might occur even around simple periodic structures, it is meaningful to understand wave phenomenon around offshore structures and develop innovative technology.
文摘安胜安全操作系统是自主研制的基于 Linux 的高安全等级安全操作系统,包括安全内核,安全架构与安全模型.总结了对该系统进行的隐蔽通道分析方法,首次报道基于 Linux 内核开发的安全操作系统的隐蔽通道分析结果.应用新型的“回溯方法”发现了某些新的隐蔽通道.对被标识的隐蔽通道,准确地计算了它们的带宽,并进行了适当的隐蔽通道处理.
