Improved Successive Cancellation Decoding of Polar Codes

As improved versions of successive cancellation (SC) decoding algorithm, successive cancellation list (SCL) decoding and successive cancellation stack (SCS) decoding are used to improve the finite-length performance of polar codes. Unified descriptions of SC, SCL and SCS decoding algorithms are given as path searching procedures on the code tree of polar codes. Combining the ideas of SCL and SCS, a new decoding algorithm named successive cancellation hybrid (SCH) is proposed, which can achieve a better trade-off between computational complexity and space complexity. Further, to reduce the complexity, a pruning technique is proposed to avoid unnecessary path searching operations. Performance and complexity analysis based on simulations show that, with proper configurations, all the three improved successive cancellation (ISC) decoding algorithms can have a performance very close to that of maximum-likelihood (ML) decoding with acceptable complexity. Moreover, with the help of the proposed pruning technique, the complexities of ISC decoders can be very close to that of SC decoder in the moderate and high signal-to-noise ratio (SNR) regime.Comment: This paper is modified and submitted to IEEE Transactions on Communication

Are Smell-Based Metrics Actually Useful in Effort-Aware Structural Change-Proneness Prediction? An Empirical Study

Bad code smells (also named as code smells) are symptoms of poor design choices in implementation. Existing studies empirically confirmed that the presence of code smells increases the likelihood of subsequent changes (i.e., change-proness). However, to the best of our knowledge, no prior studies have leveraged smell-based metrics to predict particular change type (i.e., structural changes). Moreover, when evaluating the effectiveness of smell-based metrics in structural change-proneness prediction, none of existing studies take into account of the effort inspecting those change-prone source code. In this paper, we consider five smell-based metrics for effort-aware structural change-proneness prediction and compare these metrics with a baseline of well-known CK metrics in predicting particular categories of change types. Specifically, we first employ univariate logistic regression to analyze the correlation between each smellbased metric and structural change-proneness. Then, we build multivariate prediction models to examine the effectiveness of smell-based metrics in effort-aware structural change-proneness prediction when used alone and used together with the baseline metrics, respectively. Our experiments are conducted on six Java open-source projects with up to 60 versions and results indicate that: (1) all smell-based metrics are significantly related to structural change-proneness, except metric ANS in hive and SCM in camel after removing confounding effect of file size; (2) in most cases, smell-based metrics outperform the baseline metrics in predicting structural change-proneness; and (3) when used together with the baseline metrics, the smell-based metrics are more effective to predict change-prone files with being aware of inspection effort

The Supplemental Nutrition Assistance Program (SNAP): An analysis of changing political climates, welfare policies, and their subsequent impacts on immigrants and their families in San Diego, California

This study examines the current political climate's effect on perceptions revolving around the SNAP (Supplemental Nutrition Assistance Program), also known as CalFresh, among immigrant groups located in San Diego County, California. Through a review of background information, primary source analysis (qualitative semi-structured interviews with officials, non-profit organization leaders and employees) and analysis of existing secondary research (nationwide and California-specific SNAP enrollment numbers), this study examines how the hostility and changing policies around welfare policy and SNAP impacts immigrant groups and their willingness to enroll in the program. It also examines the historical circumstances that affect perceptions towards the SNAP program today. This research provides planners with an understanding of the additional difficulties that immigrant groups face that can help aid and inform food policy and other related decisions with economic development, our built environment and social equity

The Impact on Portfolio Credit Risk with Different Correlation Assumptions

The main idea of this paper is to apply default analysis to the Student Investment Advisory Service (SIAS) fixed income portfolio, which contains 19 bonds. The portfolio credit risk analysis includes default probability, simulation of default time by using Gaussian copula and t copula, Economic Capital, Credit Value at Risk (VaR) and Expected Tail Loss (ETL)

A model‐data study of the 1999 St. Lawrence Island polynya in the Bering Sea

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95536/1/jgrc12221.pd

Fabricating hemocompatible bi-continuous PEGylated PVDF membranes via vapor-induced phase inversion

Lack of knowledge on their hemocompatibility limit the use of PVDF membranes in biomedical applications. Herein, we investigated the in situ modification of PVDF membranes by a PEGylated copolymer (PS60-b-PEGMA108) using vapor-induced phase separation (VIPS) process. Efforts were first oriented toward the characterization of the effect of copolymer on membrane formation, membranes physical properties and membranes surface chemistry. Then, biofouling was investigated before moving onto the hemocompatibility of membranes. Membranes structure tended to evolve from nodular to bi-continuous with PS60-b-PEGMA108 content, evidencing a change of dominating phenomena during phase inversion (crystallization-gelling vs. non-crystallization gelling), associated to a change of prevailing crystalline polymorph (β-polymorph vs. α-polymorph). Furthermore, the hydration of membranes was importantly enhanced, affecting nano-biofouling: bovine serum albumin, lysozyme and fibrinogen adsorption were drastically reduced, despite rough surfaces, highlighting the efficiency of the copolymer. Bacterial attachment tests revealed that macro-biofouling was inhibited as well. Results of erythrocytes, leukocytes, and thrombocytes adhesion indicated that membranes prepared from a casting solution containing 5 wt% copolymer are highly hemocompatible, result supported by low hemolysis ratio (1%) and delay of plasma clotting time. Overall, this study unveils that in situ modification coupled to the VIPS method can readily lead to hemocompatible PVDF membranes

Insights into high temperature pretreatment on cellulase processing of bamboo

Bamboo processing was performed with commercial cellulase. The properties of cellulase and the effect of high temperature pretreatment on cellulase hydrolysis of bamboo were investigated. Results indicated that cellulase hydrolysis performed fast and dramatically within 30 minutes, and then gradually reached its balance. It was found that pretreatment played an active role in cellulase processing, which enhanced the saccharification of bamboo and benefited high-molecular-weight lignin degradation and removal. Additionally, a better performance of bamboo processing was achieved under the cellulase concentration of 15IU in total reaction system of 100 ml at 50°C, pH 4.8, together with the high temperature pretreatment of 120°C for 15 minutes