Low-complexity high-speed VLSI design of low-density parity-check decoders

Low-Density Parity-check (LDPC) codes have attracted considerable attention due to their capacity approaching performance over AWGN channel and highly parallelizable decoding schemes. They have been considered in a variety of industry standards for the next generation communication systems. In general, LDPC codes achieve outstanding performance with large codeword lengths (e.g., N>1000 bits), which lead to a linear increase of the size of memory for storing all the soft messages in LDPC decoding. In the next generation communication systems, the target data rates range from a few hundred Mbit/sec to several Gbit/sec. To achieve those very high decoding throughput, a large amount of computation units are required, which will significantly increase the hardware cost and power consumption of LDPC decoders. LDPC codes are decoded using iterative decoding algorithms. The decoding latency and power consumption are linearly proportional to the number of decoding iterations. A decoding approach with fast convergence speed is highly desired in practice. This thesis considers various VLSI design issues of LDPC decoder and develops efficient approaches for reducing memory requirement, low complexity implementation, and high speed decoding of LDPC codes. We propose a memory efficient partially parallel decoder architecture suited for quasi-cyclic LDPC (QC-LDPC) codes using Min-Sum decoding algorithm. We develop an efficient architecture for general permutation matrix based LDPC codes. We have explored various approaches to linearly increase the decoding throughput with a small amount of hardware overhead. We develop a multi-Gbit/sec LDPC decoder architecture for QC-LDPC codes and prototype an enhanced partially parallel decoder architecture for a Euclidian geometry based LDPC code on FPGA. We propose an early stopping scheme and an extended layered decoding method to reduce the number of decoding iterations for undecodable and decodable sequence received from channel. We also propose a low-complexity optimized 2-bit decoding approach which requires comparable implementation complexity to weighted bit flipping based algorithms but has much better decoding performance and faster convergence speed

Traffic Circle Administration Based on Circuit Principles and Marginal Benefit Theory

AbstractIn this paper, a comprehensive model is constructed aiming at solving traffic circle problem which greatly bothers the modern society. Firstly, the quantification approach to assess the clog degree is put forward according to the description of electrical power in circuit principles. Then making use of the economic concept of marginal cost and relationship between supply and demand, judgment can be made on the changing rule of marginal social benefit when every unit of money is spent on the issue to improve traffic circle conditions. The intersection point when marginal social benefit turns from positive to negative is the best point for government to invest on the road conditions. Combined with conflict degree, we determine using different methods under various circumstances: laying stop or yield sign, placing traffic lights, or limiting the highest speed. In addition, consulting the mechanism of primary response circuit, we establish the method to set time for traffic lights. At last, an instance analysis is set for Xiamen Lianban traffic circle and the result shows that our research can reasonably deal with the practical problem

Synthesis of Silver Nanowires with Reduced Diameters Using Benzoin-Derived Radicals to Make Transparent Conductors with High Transparency and Low Haze.

Reducing the diameter of silver nanowires has been proven to be an effective way to improve their optoelectronic performance by lessening light attenuation. The state-of-the-art silver nanowires are typically around 20 nm in diameter. Herein we report a modified polyol synthesis of silver nanowires with average diameters as thin as 13 nm and aspect ratios up to 3000. The success of this synthesis is based on the employment of benzoin-derived radicals in the polyol approach and does not require high-pressure conditions. The strong reducing power of radicals allows the reduction of silver precursors to occur at relatively low temperatures, wherein the lateral growth of silver nanowires is restrained because of efficient surface passivation. The optoelectronic performance of as-prepared 13 nm silver nanowires presents a sheet resistance of 28 Ω sq-1 at a transmittance of 95% with a haze factor of ∼1.2%, comparable to that of commercial indium tin oxide (ITO)

A Preliminary Impact Study of CYGNSS Ocean Surface Wind Speeds on Numerical Simulations of Hurricanes

The NASA Cyclone Global Navigation Satellite System (CYGNSS) was launched in December 2016, providing an unprecedented opportunity to obtain ocean surface wind speeds including wind estimates over the hurricane inner‐core region. This study demonstrates the influence of assimilating an early version of CYGNSS observations of ocean surface wind speeds on numerical simulations of two notable landfalling hurricanes, Harvey and Irma (2017). A research version of the National Centers for Environmental Prediction operational Hurricane Weather Research and Forecasting model and the Gridpoint Statistical Interpolation‐based hybrid ensemble three‐dimensional variational data assimilation system are used. It is found that the assimilation of CYGNSS data results in improved track, intensity, and structure forecasts for both hurricane cases, especially for the weak phase of a hurricane, implying potential benefits of using such data for future research and operational applications.Plain Language SummaryThe NASA Cyclone Global Navigation Satellite System (CYGNSS) was launched in December 2016. It provides an unprecedented opportunity to obtain ocean surface wind speeds over a hurricane inner‐core region. In this study, we combined the early version of CYGNSS data with all other observations that are currently available for operational forecasts to form initial conditions (inputs data) for a numerical weather prediction model. A research version of the National Oceanic and Atmospheric Administration operational hurricane forecast model named the Hurricane Weather Research and Forecast (HWRF) model is used. Results show that adding CYGNSS data into HWRF model results in improved track, intensity, and structure forecasts for two notable landfalling hurricanes, Harvey and Irma (2017), demonstrating the potential benefits of using CYGNSS data for future research and operational applications.Key PointsThe NASA Cyclone Global Navigation Satellite System (CYGNSS) provides an unprecedented opportunity to obtain ocean surface wind data over a hurricane inner‐core regionThis study found that the assimilation of CYGNSS data results in improved track, intensity, and structure forecasts for two notable landfalling hurricanes, Harvey and Irma (2017)Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148339/1/grl58695.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148339/2/grl58695_am.pd

Isolation and characterization of α-amylase from marine Pseudomonas sp. K6-28-040

The α-amylase of marine Pseudomonas sp. K6-28-040 was purified through a series of three steps and the purity of enzymes was checked by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results showed that, the enzyme was purified 4.7-fold with a specific activity of 134.6 U/mg protein and a yield of 44%. When it was subjected to SDS-PAGE, a single band near 58 kDa appeared. The optimum temperature and pH were 50°C and 7.0, respectively. The addition of Ca2+, Mn2+ and Co2+ could improve the enzyme activity, while Cu2+, Hg2+, Fe3+ and Al3+ decreased the activity. The enzyme was inhibited by ethylenediaminetetraacetic acid (EDTA), ethylenebis(oxonitrilo)]tetra-acetate (EGTA), SDS and dimethyl sulfoxide (DMSO), but was not affected by phenylmethane-sulfonyl fluoride (PMSF) and 1,4-dithiothreitol (DTT). Km and Vmax values of the purified enzyme for soluble starch were 1.73 ± 0.3 mg/ml and 1.24 ± 0.02 mg/ml/min, respectively. The degradation ability of wild type α amylase on starch granules was examined by thin layer chromatography. The final purified enzyme had an isoelectric point of 7.5-7.8 and α-helix of 28%, β-sheet of 32% and random coil of 40%.Keywords: α-Amylase; Pseudomonas sp., purification, enzyme characterizatio