Rate-compatible spatially coupled repeat-accumulate codes via successive extension

A rate-compatible spatially coupled repeat-accumulate (RC-SC-RA) code is proposed. Its protograph is obtained by extending a given (J, K, L) SC-RA coupled chain (denoted as the mother chain) with extra check nodes and parity bit nodes T times. At each time, the extension is realized via coupling the message bits in the same way as that in the mother chain. Rate-compatibility is achieved by adjusting the extension parameters and applying random puncturing technique. Density evolution analysis shows that the iterative decoding thresholds of all the member codes in the proposed RC-SC-RA code family are very close to Shannon limits over the binary erasure channel. Finite length simulation results are consistent with the thresholds well. Moreover, the proposed RC-SC-RA codes perform better than spatially coupled low density parity check (SC-LDPC) codes in decoding performance especially in lower-rate region.

Visuospatial properties of caudal area 7b in Macaca fascicularis

To proceed from sensation to movement,integration and transformation of information from different senses and reference frames are required.Several brain areas are involved in this transformation process,but previous neuroanatomical and neurophysiological studies have implicated the caudal area 7b as one particular component of this transformation system.In this study,we present the first quantitative report on the spatial coding properties of caudal area 7b.The results showed that neurons in this area had intermediate component characteristics in the transformation system;the area contained bimodal neurons,and neurons in this area encode spatial information using a hybrid reference frame.These results provide evidence that caudal area 7b may belong to the reference frame transformation system,thus contributing to our general understanding of the transformation system.

Visuospatial properties of caudal area 7b in Macaca fascicularis

To proceed from sensation to movement, integration and transformation of information from different senses and reference frames are required. Several brain areas are involved in this transformation process, but previous neuroanatomical and neurophysiological studies have implicated the caudal area 7b as one particular component of this transformation system. In this study, we present the first quantitative report on the spatial coding properties of caudal area 7b. The results showed that neurons in this area had intermediate component characteristics in the transformation system; the area contained bimodal neurons, and neurons in this area encode spatial information using a hybrid reference frame. These results provide evidence that caudal area 7b may belong to the reference frame transformation system, thus contributing to our general understanding of the transformation system.

Low-Density Parity-Check Codes: Research Status and Development Direction

In this paper, we conclude five kinds of methods for construction of the regular low-density parity matrix H and three kinds of methods for the construction of irregular low-density parity-check matrix H. Through the analysis of the code rate and parameters of these eight kinds of structures, we find that the construction of low-density parity-check matrix tends to be more flexible and the parameter variability is enhanced. We propose that the current development cost should be lower with the progress of electronic technology and we need research on more practical Low-Density Parity-Check Codes (LDPC). Combined with the application of the quantum distribution key, we urgently need to explore the research direction of relevant theories and technologies of LDPC codes in other fields of quantum information in the future.

Influence of Solid Rocket Motor Slag on the Space Debris Environment

The resulting slag particles from solid rocket motor( SRM) firings are an important component of space debris environment. Slag sizes as large as 1 cm have been witnessed in ground tests,and comparable sizes have been also estimated via observations of sub-orbital tail-off events. We achieve slag initial data based on MASTER slag model and SRM historical launch data,and propagate slag long-term orbital evolution taking into account the zonal harmonics J2,atmospheric drag,solar radiation pressure and luni-solar attraction to discuss the slag size distribution and orbital characteristics. Finally,future slag debris environment is evaluated based on two different launch rate assumptions. The result shows that current launch frequency will make the slag population sustain growth and the population will not decrease at once even if there are no more launches in the future.

Encoding Spatial Context for Large-Scale Partial-Duplicate Web Image Retrieval

Many recent state-of-the-art image retrieval approaches are based on Bag-of-Visual-Words model and represent an image with a set of visual words by quantizing local SIFT（scale invariant feature transform） features. Feature quantization reduces the discriminative power of local features and unavoidably causes many false local matches between images, which degrades the retrieval accuracy. To filter those false matches, geometric context among visual words has been popularly explored for the verification of geometric consistency. However, existing studies with global or local geometric verification are either computationally expensive or achieve limited accuracy. To address this issue, in this paper, we focus on partialduplicate Web image retrieval, and propose a scheme to encode the spatial context for visual matching verification. An efficient affine enhancement scheme is proposed to refine the verification results. Experiments on partial-duplicate Web image search, using a database of one million images, demonstrate the effectiveness and efficiency of the proposed approach.Evaluation on a 10-million image database further reveals the scalability of our approach.

Semi-LDPC Convolutional Codes:Construction and Low-Latency Windowed List Decoding

This paper presents a new coding scheme called semi-low-density parity-check convolutional code(semi-LDPC-CC),whose parity-check matrix consists of both sparse and dense sub-matrices,a feature distinguished from the conventional LDPC-CCs.We propose sliding-window list(SWL)decoding algorithms with a fixed window size of two,resulting in a low decoding latency but a competitive error-correcting performance.The performance can be predicted by upper bounds derived from the first event error probability and by genie-aided(GA)lower bounds estimated from the underlying LDPC block codes(LDPC-BCs),while the complexity can be reduced by truncating the list with a threshold on the difference between the soft metrics in the serial decoding implementation.Numerical results are presented to validate our analysis and demonstrate the performance advantage of the semi-LDPC-CCs over the conventional LDPC-CCs.

Dynamics about Neural Array with Simple Lateral Inhibitory Connections

Lateral inhibitory effect is a well-known feature of information processing in neural systems.This paper presents a neural array model with simple lateral inhibitory connections.After detailed examining into the dynamics of this kind of neural array,the author gives the sufficient conditions under which the outputs of the network will tend to a special stable pattern called spatial sparse pattern in which if the output of a neuron is 1,then the outputs of the neurons in its neighborhood are 0.This ability called spatial sparse coding plays an important role in self-coding,self-organization and associative memory for patterns and pattern sequences.The main conclusions about the dynamics of this kind of neural array which is related to spatial sparse coding are introduced.