New Constructions of Zero-Correlation Zone Sequences

In this paper, we propose three classes of systematic approaches for constructing zero correlation zone (ZCZ) sequence families. In most cases, these approaches are capable of generating sequence families that achieve the upper bounds on the family size ($K$) and the ZCZ width ($T$) for a given sequence period ($N$). Our approaches can produce various binary and polyphase ZCZ families with desired parameters $(N,K,T)$ and alphabet size. They also provide additional tradeoffs amongst the above four system parameters and are less constrained by the alphabet size. Furthermore, the constructed families have nested-like property that can be either decomposed or combined to constitute smaller or larger ZCZ sequence sets. We make detailed comparisons with related works and present some extended properties. For each approach, we provide examples to numerically illustrate the proposed construction procedure.Comment: 37 pages, submitted to IEEE Transactions on Information Theor

The Magnitude of Switching Costs for Corporate Antivirus Software Switching Decision

Today’s businesses environment is forcing companies to become increasingly more efficient in applying Internet technology to conduct transactions. AS the possibility of infection by computer virus is much greater now than ever before, businesses search for appropriate corporate antivirus software to safeguard their computer systems. This paper considers corporate antivirus software switching as one of the major security selection problem and proposes possible avenues for software switching decision and management. In conceptual model, we draw upon switching costs where transaction costs, learning costs, and artificial costs were examined as main costs for software switching decision. Our findings shown only two out of three types of switching costs have influence over corporate antivirus software switching decisions. Despite the existence of switching costs, businesses continue to repeat software switching because the perceived risks of security threats are much greater than the switching cost itself. Furthermore, we examine various approaches to the cost of switching and then propose an index map to evaluate switching decision. Five sets of propositions are advanced to help guide this research

Productivity Change in Taiwan's Farmers' Credit Unions: A Nonparametric Risk-Adjusted Malmquist Approach

This article proposes an extended three-stage DEA methodology similar to Fried et al. (2002) to improve the measurement of productivity growth then the assumption of free disposability of undesirable outpu t does not apply. A directional distance function is used to construct adjusted Malmquist-Luenberger productivity indexes which simultaneously account for the impacts of undesirable outputs, environmental variables, and statistical noise. Panel data for 264 farmers' credit unions (FCUs) in Taiwan covering the 1998-2000 period are employed to illustrate the advantages of this method. On average, the productivity of Taiwan's FCUs is found to have deteriorated over the 1998-2000 period. Although an improvement in efficiency has been observed, the major reason for the deterioration is found to be due to the regression of techno logy.Malmquist-Luenberger productivity index, three-stage DEA, undesirable outputs, directional distance function, Agricultural Finance, Productivity Analysis,