Low-Density Arrays of Circulant Matrices: Rank and Row-Redundancy Analysis, and Quasi-Cyclic LDPC Codes

This paper is concerned with general analysis on the rank and row-redundancy of an array of circulants whose null space defines a QC-LDPC code. Based on the Fourier transform and the properties of conjugacy classes and Hadamard products of matrices, we derive tight upper bounds on rank and row-redundancy for general array of circulants, which make it possible to consider row-redundancy in constructions of QC-LDPC codes to achieve better performance. We further investigate the rank of two types of construction of QC-LDPC codes: constructions based on Vandermonde Matrices and Latin Squares and give combinatorial expression of the exact rank in some specific cases, which demonstrates the tightness of the bound we derive. Moreover, several types of new construction of QC-LDPC codes with large row-redundancy are presented and analyzed.Comment: arXiv admin note: text overlap with arXiv:1004.118

LITHIUM ISOTOPIC CONSTRAINTS ON THE ORIGIN OF I- AND A-TYPE GRANITES FROM EAST JUNGGAR (NW CHINA) OF THE CENTRAL ASIAN OROGENIC BELT: IMPLICATIONS FOR LI ISOTOPIC FRACTIONATION DURING CRUSTAL ANATEXIS

Though Li isotope fractionation during mantle melting and differentiation of basaltic melts have been proved insignificant, Li isotopic systems during crustal processes remain unclear. To study this, we report combined petrological, Nd-Sr and Li isotopic data for the late Paleozoic coexisting I- and A-type granites in the East Junggar orogen of the Central Asian Orogenic Belt. The granites were formed responding to underplating of mafic magmas in the lower crust in a postcollisional, extensional regime, and intruded into the Paleozoic foldbelts that formed due to extensive oceanic subduction-accretion processes.Though Li isotope fractionation during mantle melting and differentiation of basaltic melts have been proved insignificant, Li isotopic systems during crustal processes remain unclear. To study this, we report combined petrological, Nd-Sr and Li isotopic data for the late Paleozoic coexisting I- and A-type granites in the East Junggar orogen of the Central Asian Orogenic Belt. The granites were formed responding to underplating of mafic magmas in the lower crust in a postcollisional, extensional regime, and intruded into the Paleozoic foldbelts that formed due to extensive oceanic subduction-accretion processes

Human Resource Management & Knowledge-Based Management -- A study of HR practices in performance-related knowledge management

Human resource management has increasingly become to a significant part of organizational management. The existing literatures related to Strategic HRM currently are closely referred to the resource-based view of the firm to explain and analyze the correlation between human capital and the sustention of competitive advantage. In view of resource-based development under the competitive dynamic environment, the economy has changed from the product-based to mainly knowledge-based. Knowledge-related resource has become to one of the key source in managerial strategy and significantly influences organizations productivity and business performance. Accordingly, knowledge and knowledge workers are highly required by organizations to abreast with the rapid innovation of information technology. Effective knowledge management together with strategic HR practices therefore assists organizations to enhance ability to achieve expected business performance. HR practices in the way of knowledge-based management in this study is related to the adoption of recruitment and selection, training and development, career planning and retention, knowledge sharing, and motivation for work performance. The aims and objectives of this study, consequently, are firstly via a methodic literature review to understand the general theories and perspectives of HRM, knowledge management, the implementation of HR practices, and the adoption of HRM in Chinese enterprises. Furthermore, primary research via interviews of three Chinese knowledge-intensive enterprises mainly focus on investigating and analyzing how HR managers use such practices to manage knowledge workers, and how knowledge workers respond organizational management, based on existing theories and conceptions. From this study, in view of the phenomenon of developing human resource in order for competitive advantage and business performance, organizations in China increasingly become conscious of the importance of HRM. The use of HR practices based on Chinese enterprises particular cultures and business strategies, however, is essentially different from the general conceptions and practices in Western organizations

Element Replacement Approach by Reaction with Lewis Acidic Molten Salts to Synthesize Nanolaminated MAX Phases and MXenes

Nanolaminated materials are important because of their exceptional properties and wide range of applications. Here, we demonstrate a general approach to synthesize a series of Zn-based MAX phases and Cl-terminated MXenes originating from the replacement reaction between the MAX phase and the late transition metal halides. The approach is a top-down route that enables the late transitional element atom (Zn in the present case) to occupy the A site in the pre-existing MAX phase structure. Using this replacement reaction between Zn element from molten ZnCl2 and Al element in MAX phase precursors (Ti3AlC2, Ti2AlC, Ti2AlN, and V2AlC), novel MAX phases Ti3ZnC2, Ti2ZnC, Ti2ZnN, and V2ZnC were synthesized. When employing excess ZnCl2, Cl terminated MXenes (such as Ti3C2Cl2 and Ti2CCl2) were derived by a subsequent exfoliation of Ti3ZnC2 and Ti2ZnC due to the strong Lewis acidity of molten ZnCl2. These results indicate that A-site element replacement in traditional MAX phases by late transition metal halides opens the door to explore MAX phases that are not thermodynamically stable at high temperature and would be difficult to synthesize through the commonly employed powder metallurgy approach. In addition, this is the first time that exclusively Cl-terminated MXenes were obtained, and the etching effect of Lewis acid in molten salts provides a green and viable route to prepare MXenes through an HF-free chemical approach.Comment: Title changed; experimental section and discussion revise

CAT: Learning to Collaborate Channel and Spatial Attention from Multi-Information Fusion

Channel and spatial attention mechanism has proven to provide an evident performance boost of deep convolution neural networks (CNNs). Most existing methods focus on one or run them parallel (series), neglecting the collaboration between the two attentions. In order to better establish the feature interaction between the two types of attention, we propose a plug-and-play attention module, which we term "CAT"-activating the Collaboration between spatial and channel Attentions based on learned Traits. Specifically, we represent traits as trainable coefficients (i.e., colla-factors) to adaptively combine contributions of different attention modules to fit different image hierarchies and tasks better. Moreover, we propose the global entropy pooling (GEP) apart from global average pooling (GAP) and global maximum pooling (GMP) operators, an effective component in suppressing noise signals by measuring the information disorder of feature maps. We introduce a three-way pooling operation into attention modules and apply the adaptive mechanism to fuse their outcomes. Extensive experiments on MS COCO, Pascal-VOC, Cifar-100, and ImageNet show that our CAT outperforms existing state-of-the-art attention mechanisms in object detection, instance segmentation, and image classification. The model and code will be released soon.Comment: 8 pages, 5 figure

Efficient Approximation Algorithms for Adaptive Seed Minimization

As a dual problem of influence maximization, the seed minimization problem asks for the minimum number of seed nodes to influence a required number $\eta$ of users in a given social network $G$. Existing algorithms for seed minimization mostly consider the non-adaptive setting, where all seed nodes are selected in one batch without observing how they may influence other users. In this paper, we study seed minimization in the adaptive setting, where the seed nodes are selected in several batches, such that the choice of a batch may exploit information about the actual influence of the previous batches. We propose a novel algorithm, ASTI, which addresses the adaptive seed minimization problem in $O\Big(\frac{\eta \cdot (m+n)}{\varepsilon^2}\ln n \Big)$ expected time and offers an approximation guarantee of $\frac{(\ln \eta+1)^2}{(1 - (1-1/b)^b) (1-1/e)(1-\varepsilon)}$ in expectation, where $\eta$ is the targeted number of influenced nodes, $b$ is size of each seed node batch, and $\varepsilon \in (0, 1)$ is a user-specified parameter. To the best of our knowledge, ASTI is the first algorithm that provides such an approximation guarantee without incurring prohibitive computation overhead. With extensive experiments on a variety of datasets, we demonstrate the effectiveness and efficiency of ASTI over competing methods.Comment: A short version of the paper appeared in 2019 International Conference on Management of Data (SIGMOD '19), June 30--July 5, 2019, Amsterdam, Netherlands. ACM, New York, NY, USA, 18 page