In view of the low ranging efficiency of the conventional fixed frame-length algorithm in the inter-satellite link,an adaptive frame-length algorithm is proposed. The frame length is adjusted adaptively according to t...In view of the low ranging efficiency of the conventional fixed frame-length algorithm in the inter-satellite link,an adaptive frame-length algorithm is proposed. The frame length is adjusted adaptively according to the results of ranging and velocity measuring to improve ranging efficiency. Buffers which enable the frame length to be selected discretely and adaptively are introduced to avoid frequent hopping of the frame-length.Frame length marker is created to automatically identify the frame-length for frame synchronization procedures in receivers. The feasibility and the validity of the proposed algorithm to improve the efficiency of ranging are verified through both theoretic analysis and simulation,and the efficiency improves up to 88% when there are five buffers. This improvement can be further enhanced by increasing the number of buffers. Proper allocation of inter-satellite buffers is required to make a balance between the ranging efficiency and the system complexity.展开更多
According to the issues that the predict errors of chaotic sequences rapidly accumulated in multi-step forecasting which affects the predict accuracy, we proposed a new predict algorithm based on local modeling with v...According to the issues that the predict errors of chaotic sequences rapidly accumulated in multi-step forecasting which affects the predict accuracy, we proposed a new predict algorithm based on local modeling with variable frame length and interpolation points. The core idea is that, using interpolation method to increase the available sample data, then modeling the chaos dynamics system with least square algorithm which based on the Bernstein polynomial to realize the forecasting. We use the local modeling method, looking for the optimum frame length and interpolation points in every frame to improve the predict peformance. The experimental results show that the proposed algorithm can improve the predictive ability effectively, decreasing the accumulation of iterative errors in multi-step prediction.展开更多
The fundamental frequency plays a significant part in understanding and perceiving the pitch of a sound. The pitch is a fundamental attribute employed in numerous speech-related works. For fundamental frequency extrac...The fundamental frequency plays a significant part in understanding and perceiving the pitch of a sound. The pitch is a fundamental attribute employed in numerous speech-related works. For fundamental frequency extraction, several algorithms have been developed which one to use relies on the signal’s characteristics and the surrounding noise. Thus, the algorithm’s noise resistance becomes more critical than ever for precise fundamental frequency estimation. Nonetheless, numerous state-of-the-art algorithms face struggles in achieving satisfying outcomes when confronted with speech recordings that are noisy with low signal-to-noise ratio (SNR) values. Also, most of the recent techniques utilize different frame lengths for pitch extraction. From this point of view, This research considers different frame lengths on male and female speech signals for fundamental frequency extraction. Also, analyze the frame length dependency on the speech signal analytically to understand which frame length is more suitable and effective for male and female speech signals specifically. For the validation of our idea, we have utilized the conventional autocorrelation function (ACF), and state-of-the-art method BaNa. This study puts out a potent idea that will work better for speech processing applications in noisy speech. From experimental results, the proposed idea represents which frame length is more appropriate for male and female speech signals in noisy environments.展开更多
To reach necessary end-to-end connectivity between the Internet and wireless sensor networks （WSNs）, the Internet Engineering Task Force （IETF） IPv6 over low power wireless personal area network （6LowPAN） workin...To reach necessary end-to-end connectivity between the Internet and wireless sensor networks （WSNs）, the Internet Engineering Task Force （IETF） IPv6 over low power wireless personal area network （6LowPAN） working group has been established and introduced an adaptation layer for integration of IEEE 802.15.4 physical layer/media access control （PHY/MAC） layers and the upper layers of any Intemet protocol （IP）-based networks, such as the Internet. The energy efficiency is one of the most important performance measures in WSNs because most sensor nodes are only battery powered so we should reduce the energy consumption to the lowest to extend the life of nodes. Therefore the determination of MAC frame length should be carefully considered since that the radio frequency （RF） module consumes most the energy of a sensor node meanwhile the MAC protocol is the direct controller of RF module. In this paper, we provide a star-shaped 6LowPAN non-beacon mode with unslotted carrier sense multiple access with collision avoidance （CSMA/CA） mechanism to access to the channel and model the stochastic behavior of a target end node as the M/G/1 queuing system. Analytical expressions for some parameters such as channel busy probability, packet loss probability and energy efficiency are obtained in this paper and our analytical results can clearly show the impact of MAC frame length on the energy efficiency of a target node in both ideal and lossy channel.展开更多
Four exterior joints with special-shaped columns which have different lengths of limbs are tested under low cyclic loading. Speeial-shaped columns adopted are L- and T-shaped in section. It can be concluded that crack...Four exterior joints with special-shaped columns which have different lengths of limbs are tested under low cyclic loading. Speeial-shaped columns adopted are L- and T-shaped in section. It can be concluded that crack pattern, failure mode and shear strength of joints are affected by the length of limb, and that shear strength and ductility increase with the length of limb; the joints with the flexural failure of the beam have better seismic behavior than those with the shear failure of the joint core.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
为提高射频识别(Radio frequency identification,RFID)标签的识别效率,本文针对RFID动态帧时隙ALOHA防冲突系统,提出了新的标签估计方法和帧长确定方案.标签估计中采用了不同的贝叶斯代价函数,提出了几种贝叶斯标签估计方法,它们的估...为提高射频识别(Radio frequency identification,RFID)标签的识别效率,本文针对RFID动态帧时隙ALOHA防冲突系统,提出了新的标签估计方法和帧长确定方案.标签估计中采用了不同的贝叶斯代价函数,提出了几种贝叶斯标签估计方法,它们的估计结果准确,而且通过减小标签数取值范围可使计算复杂度得到降低.随后,推导出一种根据标签数确定最优帧长的方案,它能使系统达到最大的信道利用率,该最大信道利用率要大于帧的时隙数等于标签数时所能达到的最大利用率.展开更多
基金Supported by the National High Technology Research and Development Program of China(2013AA1548)
文摘In view of the low ranging efficiency of the conventional fixed frame-length algorithm in the inter-satellite link,an adaptive frame-length algorithm is proposed. The frame length is adjusted adaptively according to the results of ranging and velocity measuring to improve ranging efficiency. Buffers which enable the frame length to be selected discretely and adaptively are introduced to avoid frequent hopping of the frame-length.Frame length marker is created to automatically identify the frame-length for frame synchronization procedures in receivers. The feasibility and the validity of the proposed algorithm to improve the efficiency of ranging are verified through both theoretic analysis and simulation,and the efficiency improves up to 88% when there are five buffers. This improvement can be further enhanced by increasing the number of buffers. Proper allocation of inter-satellite buffers is required to make a balance between the ranging efficiency and the system complexity.
文摘According to the issues that the predict errors of chaotic sequences rapidly accumulated in multi-step forecasting which affects the predict accuracy, we proposed a new predict algorithm based on local modeling with variable frame length and interpolation points. The core idea is that, using interpolation method to increase the available sample data, then modeling the chaos dynamics system with least square algorithm which based on the Bernstein polynomial to realize the forecasting. We use the local modeling method, looking for the optimum frame length and interpolation points in every frame to improve the predict peformance. The experimental results show that the proposed algorithm can improve the predictive ability effectively, decreasing the accumulation of iterative errors in multi-step prediction.
文摘The fundamental frequency plays a significant part in understanding and perceiving the pitch of a sound. The pitch is a fundamental attribute employed in numerous speech-related works. For fundamental frequency extraction, several algorithms have been developed which one to use relies on the signal’s characteristics and the surrounding noise. Thus, the algorithm’s noise resistance becomes more critical than ever for precise fundamental frequency estimation. Nonetheless, numerous state-of-the-art algorithms face struggles in achieving satisfying outcomes when confronted with speech recordings that are noisy with low signal-to-noise ratio (SNR) values. Also, most of the recent techniques utilize different frame lengths for pitch extraction. From this point of view, This research considers different frame lengths on male and female speech signals for fundamental frequency extraction. Also, analyze the frame length dependency on the speech signal analytically to understand which frame length is more suitable and effective for male and female speech signals specifically. For the validation of our idea, we have utilized the conventional autocorrelation function (ACF), and state-of-the-art method BaNa. This study puts out a potent idea that will work better for speech processing applications in noisy speech. From experimental results, the proposed idea represents which frame length is more appropriate for male and female speech signals in noisy environments.
基金Supported by the National Natural Science Foundation of China (61071090, 61171093)the National Science and Technology Major Projects (2011ZX03005-004-003)the Innovation Project of SCI and Tech for College Graduates of Jiangsu Province (CXLX12_0475)
文摘To reach necessary end-to-end connectivity between the Internet and wireless sensor networks （WSNs）, the Internet Engineering Task Force （IETF） IPv6 over low power wireless personal area network （6LowPAN） working group has been established and introduced an adaptation layer for integration of IEEE 802.15.4 physical layer/media access control （PHY/MAC） layers and the upper layers of any Intemet protocol （IP）-based networks, such as the Internet. The energy efficiency is one of the most important performance measures in WSNs because most sensor nodes are only battery powered so we should reduce the energy consumption to the lowest to extend the life of nodes. Therefore the determination of MAC frame length should be carefully considered since that the radio frequency （RF） module consumes most the energy of a sensor node meanwhile the MAC protocol is the direct controller of RF module. In this paper, we provide a star-shaped 6LowPAN non-beacon mode with unslotted carrier sense multiple access with collision avoidance （CSMA/CA） mechanism to access to the channel and model the stochastic behavior of a target end node as the M/G/1 queuing system. Analytical expressions for some parameters such as channel busy probability, packet loss probability and energy efficiency are obtained in this paper and our analytical results can clearly show the impact of MAC frame length on the energy efficiency of a target node in both ideal and lossy channel.
文摘Four exterior joints with special-shaped columns which have different lengths of limbs are tested under low cyclic loading. Speeial-shaped columns adopted are L- and T-shaped in section. It can be concluded that crack pattern, failure mode and shear strength of joints are affected by the length of limb, and that shear strength and ductility increase with the length of limb; the joints with the flexural failure of the beam have better seismic behavior than those with the shear failure of the joint core.
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.
文摘为提高射频识别(Radio frequency identification,RFID)标签的识别效率,本文针对RFID动态帧时隙ALOHA防冲突系统,提出了新的标签估计方法和帧长确定方案.标签估计中采用了不同的贝叶斯代价函数,提出了几种贝叶斯标签估计方法,它们的估计结果准确,而且通过减小标签数取值范围可使计算复杂度得到降低.随后,推导出一种根据标签数确定最优帧长的方案,它能使系统达到最大的信道利用率,该最大信道利用率要大于帧的时隙数等于标签数时所能达到的最大利用率.
