A Simplified Min-Sum Decoding Algorithm for Non-Binary LDPC Codes

Non-binary low-density parity-check codes are robust to various channel impairments. However, based on the existing decoding algorithms, the decoder implementations are expensive because of their excessive computational complexity and memory usage. Based on the combinatorial optimization, we present an approximation method for the check node processing. The simulation results demonstrate that our scheme has small performance loss over the additive white Gaussian noise channel and independent Rayleigh fading channel. Furthermore, the proposed reduced-complexity realization provides significant savings on hardware, so it yields a good performance-complexity tradeoff and can be efficiently implemented.Comment: Partially presented in ICNC 2012, International Conference on Computing, Networking and Communications. Accepted by IEEE Transactions on Communication

A Method for Measurement of Workpiece form Deviations Based on Machine Vision

Machine vision has been studied for measurements of workpiece form deviations due to its ease of automation. However, the measurement accuracy limits its wide implementation in industrial applications. In this study, a method based on machine vision for measurement of straightness, roundness, and cylindricity of a workpiece is presented. A subsumed line search algorithm and an improved particle swarm optimization algorithm are proposed to evaluate the straightness and roundness deviations of the workpiece. Moreover, an image evaluation method of cylindricity deviation by the least-square fitting of the circle’s center coordinates is investigated. An image acquisition system incorporating image correction and sub-pixel edge positioning technology is developed. The performance of the developed system is evaluated against the measurement results of the standard cylindricity measuring instrument. The differences in the measurement of straightness, roundness, and cylindricity are −4.69 μm, 3.87 μm, and 8.51 μm, respectively. The proposed method would provide a viable industrial solution for the measurement of workpiece form deviations

Zero-sequence Current Suppressing Strategy for Dual Three-phase Permanent Magnet Synchronous Machines Connected with Single Neutral Point

Dual three-phase permanent-magnet synchronous machines (DTP-PMSM) connected with a single neutral point provide a loop for zero-sequence current (ZSC). This paper proposes a novel space vector pulse width modulation (SVPWM) strategy to suppress the ZSC. Five vectors are selected as basic voltage vectors in one switching period. The fundamental and harmonic planes and the zero-sequence plane are taken into consideration to synthesis the reference voltage vector. To suppress the ZSC, a non-zero zero-sequence voltage (ZSV) is generated to compensate the third harmonic back-EMF. Rather than triangular carrier modulation, the sawtooth carrier modulation strategy is used to generate asymmetric PWM signals. The modulation range is investigated to explore the variation of modulation range caused by considering the zero-sequence plane. With the proposed method, the ZSC can be considerably reduced. The simulated and experimental results are presented to validate the effectiveness of the proposed modulation strategy

BDNF/Trk/KCC2 pathway in nicotine withdrawal-induced hyperalgesia

Purpose: To investigate the effect of brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase (Trk) on potassium chloride cotransporter 2 (KCC2) in rats following nicotine withdrawal and the roles played by BDNF/Trk/KCC2 pathway in nicotine withdrawal-induced hyperalgesia. Methods: Seventy-eight rats were randomly assigned to five groups: control group (n = 12) without any treatment, normal saline group (NS group, n = 12) and nicotine withdrawal group (NW group, n = 30) receiving a subcutaneous injection of saline or nicotine for 7 days, respectively. The NW + dimethyl sulfoxide (DMSO) (n = 12) and NW+ Trk antagonist K252a groups (n = 12) received an intrathecal injection of DMSO (10 μl) and K252a (10 μg/10 μl) for 3 days after nicotine withdrawal, respectively. Nicotine withdrawal was precipitated by subcutaneous injection of nonselective and noncompetitive antagonist of nicotinic acetylcholine receptors mecamylamine. Pain was tested using thermal withdrawal latency (TWL). A Western blot was used to examine the expression of BDNF and KCC2. Results: The TWL was significantly decreased in NW group relative to control and NS groups (P < 0.01). Compared with the NW group, the NW+K252a group manifested a significantly higher latency (P < 0.01). The BDNF expression was increased and KCC2 was decreased in NW group compared with the control group (P < 0.01). K252a reduced KCC2 downregulation. Conclusion: BDNF/Trk signaling may contribute to nicotine withdrawal-induced hyperalgesia via downregulation of KCC2

Biomarker characteristics and oil accumulation period of Well Sutan 1 in Qaidam Basin, China

The hydrocarbon accumulation history of 2536.5 m–2697.0 m of Well Sutan 1was studied, and the geological and geochemical data including the homogenization temperature of fluid inclusion and the geochemical characteristics of the crude oil were analyzed. The results showed that the crude oil had the properties of a high degree of evolution. The precursor type was mainly high terrestrial plants. Among them, crude oil from depths of 2620.67 m, 3640.57 m and 2697 m had been charged with crude oil with aquatic organism. The crude oil was deposited in weak oxidizing to oxidizing environment with fresh to slight saline water, which is better for preservation and transformation of organics. The characteristic of fluid inclusion with Well Sutan 1 showed that there were at least three occasions of filling of oil and one of filling of gas. Also, petroleum accumulation existed in the crude oil on two occasions. The reservoir forming time of the first charge with oil was about 142 Ma, and the second charge with oil was about 107 Ma, which is tectonic inversion of the Yanshanian Orogenic Movement in the Late-Early Cretaceous

Low Complexity Encoder of High Rate Irregular QC-LDPC Codes for Partial Response Channels

High rate irregular QC-LDPC codes based on circulant permutation matrices, for efficient encoder implementation, are proposed in this article. The structure of the code is an approximate lower triangular matrix. In addition, we present two novel efficient encoding techniques for generating redundant bits. The complexity of the encoder implementation depends on the number of parity bits of the code for the one-stage encoding and the length of the code for the two-stage encoding. The advantage of both encoding techniques is that few XOR-gates are used in the encoder implementation. Simulation results on partial response channels also show that the BER performance of the proposed code has gain over other QC-LDPC codes