This paper analyzes the content shortage problems faced by museums, art galleries, private cinemas, various types of experience museums and other cultural complexes, and finds that it is mainly due to the high production cost caused by the existing production pattern of creating and producing cultural products entirely on its own. With the help of artificial intelligence technology, this paper puts forward a solution to realize the convergence of online and offline media, that is, using software technology such as video understanding and video enhancement and collecting a wide variety of audio and video programs on the Internet. Then we integrate, optimize and re-create them to overcome the defects of fragmentation and poor quality, so that the quality of cultural products can reach the level of high resolution, high color depth and high frame rate, and the cost is not so high. To meet the sustainable needs of new era cultural complex for high-quality cultural products in low price.

In our previous work, we have revealed the phenomenon of mainlobe orientation reversal (MOR) suffered by the first-order steerable differential array (FOSDA) due to microphone phase errors. However, only a deterministic analysis is conducted in that work. To provide useful guidance for practical FOSDA design, this paper further studies the problem of MOR in the presence of uncertain microphone phase errors from two perspectives, i.e., interval analysis and statistical analysis. In particular, two criteria are derived to facilitate the FOSDA design in order to avoid undesirable MOR.

It is known that differential microphone arrays are sensitive to microphone mismatches. This paper studies the effects of microphone mismatches on the directivity factor (DF) of the first-order steerable differential array (FOSDA) whose response is constructed by a linear combination of monopole and two orthogonal dipoles via a small four-microphone array. In particular, the DF of the FOSDA is studied from two perspectives, i.e., a deterministic analysis for deterministic microphone gain/phase errors, and a worst-case analysis for uncertain microphone gain/phase errors. Based on the theoretical analysis, several interesting properties are revealed, which are helpful to better understand the robustness characteristics of the FOSDA. Moreover, by worst-case analysis, it provides a useful guidance for robust FOSDA design, i.e., how to determine array size and select microphones with required characteristics such that a desired DF value can be guaranteed. In addition, the effect of sensor self-noise on the DF of the FOSDA is also discussed.

Directivity factor (DF) is a fundamental performance measure of microphone arrays. This paper studies the DF of the first-order steerable differential array (FOSDA) whose response is constructed by a linear combination of monopole and two orthogonal dipoles using a four-element square array. The DF of the ideal FOSDA and the DFs of the FOSDA with microphone gain/phase errors are derived, all in closed forms. Based on the theoretical analysis, several findings regarding the properties of the DF of the FOSDA are obtained.

To propose a synchronous and multi-domain feature extraction method of electroencephalogram (EEG) and surface electromyogram (sEMG) signals is of great significance to power-assist rehabilitation robot control with humancomputer interface (HCI). In this paper, nonnegative Tucker decomposition which is one model of nonnegative tensor factorization (NTF) is used to fuse two kinds of bioelectricity signals (EEG and sEMG) and extract multi-domain features of EEG and sEMG signals for classification which contain time, frequency, and space domains. In the first step the EEG and sEMG data are transformed into multidimensional information using continuous wavelet transform and the 4-D EEG-sEMG tensor is established. Then the tensor is decomposed into four components (spatial components, spectral components, temporal components and category components) and the core tensor is the feature extracted. The feature after being eliminated and compressed are fed into KNN, LDA and SVM classifiers for pattern recognition, and a comparison is done in single EEG analysis, single sEMG analysis and both EEG and sEMG analysis. An experiment about 10 healthy participants' upper limb movements was carried out to verify the validity of this algorithm. The result implied that NTF is a meaningful and valuable synchronous and multi-domain feature extraction method which may be promising in power-assist rehabilitation robot control.

This letter studies the mainlobe misorientation problem of the First-Order Steerable Differential Array (FOSDA) in the presence of microphone gain and phase errors, whose response is constructed by a linear combination of monopole and two orthogonal dipoles using a four-element square array. It is shown that the mainlobe orientation of the FOSDA will be undesiredly reversed in the presence of microphone phase errors if the array directivity controlling parameter is less than the corresponding lower bound. In contrast, the effect of microphone gain errors makes little difference when the array directivity controlling parameter varies. Some numerical examples are presented to evaluate the theoretical analysis.

The passive dynamic walking model, which can only depend on the gravity and its own inertia, presents stable, high-efficient, natural periodic gait on a slight slope. The stable periodic gait of the robot has a delicate balance of energy conversion, which makes the gait adjust itself as the parameters of the model change. In our work, the cell mapping method is combined with Newton-Raphson iteration to obtain the limit cycle of the periodic gait in the model, the track stability of the limit cycle is analyzed, and the eigenvalues change rule of Poincare Jacobi matrix is deduced. The influence of changing parameters on the gait is analyzed and discussed by simulations on the model with different sets of parameters. The result suggests that, the location of the center of leg mass too high or too low, foot radius increase or decrease, the slope or moment of inertia increase, will lead to the occurrence of bifurcation of the gait period and chaos; while the way the gait enters chaos from period doubling bifurcation, which results from different parameters change, obeys the law all the period doubling bifurcation share, that is, it has the same Feigenbaum constant. Furthermore, the dynamic features of the robot at the entrance of the chaos are obtained by the rule of the period doubling bifurcation of the gait; meanwhile, it can be found by the analysis of the gait features in the chaos area that there is also certain periodic law in the chaotic gait.

Orthogonal frequency division multiplexing (OFDM) is robust against frequency selective fading due to the increase of the symbol duration. As the symbol duration increases, the OFDM systems become more susceptible to time-variations. Users moving at a quite high speed suffer the inter-carrier interference caused by the time varying (TV) channels. Meanwhile, users at the cell boundary are known to experience a large inter-cell interference in a fully-loaded OFDM cellular environment with a frequency reuse factor equal to 1. In this paper, the design of pilots in the downlink at the cell boundary is addressed, aiming at mitigating the inter-cell interference under TV channel. The properties of these pilots are described, and the simulation results are presented.

This paper presents a high speed decoder architecture for irregular structured low density parity check (LDPC) codes and its field programmable gate array (FPGA) implementation. Algorithm transformation and architectural level optimizations are employed to reduce the critical path. The enhanced semi-parallel architecture is easily scalable and reconfigurable for larger block sizes and can be well suited for achieving high decoding throughput. Based on the proposed architecture, a (10240, 5120) irregular structured LDPC decoder is implemented on Xilinx FPGA Virtex-4 VLX80, the FPGA implementation results show that the irregular LDPC decoder can achieve a maximum (information data) decoding throughput of 223 Mbps at 18 iterations.

Orthogonal frequency division multiplexing (OFDM) systems encounter performance degradations due to the time varying (TV) channels in wireless environments. As delay spread increases, symbol duration should also increase, and then OFDM systems become more susceptible to time-variations. Time-variations introduce inter-carrier interference (ICI), which must be mitigated to improve the performance in high delay and Doppler spread environments. In this paper, a pilot design scheme for multiple input multiple output (MIMO) OFDM system is proposed under TV channels. The properties of these pilots are described, and the simulation results are presented.

Multiple input multiple output (MIMO) systems provide dramatic capacity gain through an increased spatial dimension. However, the capacity gain is reduced if the channel state information (CSI) is not perfect. The more exact the CSI is, the higher capacity gain we can obtain. In order to obtain higher capacity gain, this paper analyzes the two factors which mainly affect the reliability of CSI: the quality of channel estimation and the feedback delay, and proposes a channel modification strategy, which can optimally reduce the effect of the two factors and obtain more exact CSI. Simulation shows that the channel modification strategy is effective.

The traditional channel estimation for orthogonal frequency division multiplexing (OFDM) systems over fast-varying fading channels is usually carried out in two steps. Firstly obtain the least-square (LS) estimate over the pilot sub-carriers, and then interpolate it over the entire frequency-domain. In this paper, we propose a high precision channel estimation method by adding an intermediate step, which is based on the strong correlation in each path of the channel during the coherent time and can distinguish valid path taps and noise taps effectively, to improve the accuracy of the preliminary estimate over the pilot sub-carriers. The simulation results in the frequency band of 2.4 GHz show that the proposed method can obtain refined channel functions more efficiently and achieve a good bit error rate (BER) performance close to the theoretical bound of ideal channel estimation.

This paper presents a manageable overlay network architecture SVCP2P for live scalable media streaming. Every peer in SVCP2P periodically exchanges data availability information with one of distributed central servers which act as the centralized index for storing peer list, program list and buffer information of peers. An efficient scheduling algorithm is proposed, which achieves real-time and continuous transmission of the scalable streaming. There are three characteristics of this architecture: 1) easy management; 2) efficient to heterogeneous network because of the scalable media streaming adapting to the heterogeneous demand; and 3) robust and resilient. We have examined the SVCP2P which has been implemented based on the IP Internet over LAN, and the results demonstrate the efficiency of SVCP2P.

Orthogonal frequency division multiplexing (OFDM) systems encounter performance degradations due to the time varying (TV) channels in wireless environments. As delay spread increases, symbol duration should also increase, and then OFDM systems become more susceptible to time-variations. Time-variations introduce inter-carrier interference (ICI), which must be mitigated to improve the performance in high delay and Doppler spread environments. In this paper, we propose a method to estimate the TV channel. The method is designed for the comb pilot pattern. It performs a multi- symbol processing of the LS estimate over the pilot sub- carriers to detect the active paths of the channel and uses a piece-wise linear model to approximate the time-variations characteristic of each active path during each OFDM symbol to mitigate ICI. Theoretical analysis and simulation result show performance improvement in high delay and Doppler spread environments.

The Non-Line-of-Sight (NLOS) propagation effect has been considered as one of the most important issues in the location estimation especially in urban environment with serious blocking of direct paths. In this paper, we develop a new algorithm to mitigate the NLOS errors in location estimation by distributed multi-antenna. Utilizing the relativity between TOAs obtained from different antennas in a multi-antenna array, the positions of scatterers that cause the NLOS propagation, as well as the distances between mobile stations (MSs) and scatterers, are estimated. Then with appropriate location algorithm, the locations of MSs are obtained with information of scatterers. Simulation results show that this algorithm can mitigate NLOS errors effectively and improve the performance of TOA/TDOA based location algorithm in NLOS environment significantly.