Nonnegative Matrix Inequalities and their Application to Nonconvex Power Control Optimization

Maximizing the sum rates in a multiuser Gaussian channel by power control is a nonconvex NP-hard problem that finds engineering application in code division multiple access (CDMA) wireless communication network. In this paper, we extend and apply several fundamental nonnegative matrix inequalities initiated by Friedland and Karlin in a 1975 paper to solve this nonconvex power control optimization problem. Leveraging tools such as the Perron–Frobenius theorem in nonnegative matrix theory, we (1) show that this problem in the power domain can be reformulated as an equivalent convex maximization problem over a closed unbounded convex set in the logarithmic signal-to-interference-noise ratio domain, (2) propose two relaxation techniques that utilize the reformulation problem structure and convexification by Lagrange dual relaxation to compute progressively tight bounds, and (3) propose a global optimization algorithm with ϵ-suboptimality to compute the optimal power control allocation. A byproduct of our analysis is the application of Friedland–Karlin inequalities to inverse problems in nonnegative matrix theory

Maximizing sum rate and minimizing MSE on multiuser downlink: Optimality, fast algorithms and equivalence via max-min SIR

Maximizing the minimum weighted SIR, minimizing the weighted sum MSE and maximizing the weighted sum rate in a multiuser downlink system are three important performance objectives in joint transceiver and power optimization, where all the users have a total power constraint. We show that, through connections with the nonlinear Perron-Frobenius theory, jointly optimizing power and beamformers in the max-min weighted SIR problem can be solved optimally in a distributed fashion. Then, connecting these three performance objectives through the arithmetic-geometric mean inequality and nonnegative matrix theory, we solve the weighted sum MSE minimization and weighted sum rate maximization in the low to moderate interference regimes using fast algorithms

A preliminary study on the relationship between psycho graphic factors and the purchase of life insurance

This was a preliminary study conducted to examine the relationship between psycho graphic factors (i.e., personal value, risk attitude, and trust) and the purchase of life insurance among Alor Setar city folks.A non-probability convenience sampling technique was used to collect data from early February to mid-March 2015.A sample comprising 108 respondents were subjected to binary logistic regression analysis. The major finding of this study showed that risk attitude has a significant and negative relationship with the purchase of life insurance.Respondents in Alor Setar who are more likely to involve in risky behaviours or activities tend not to buy life insurance.Risk taking individuals do not behave like risk averse individuals who tend to seek protection by buying life insurance as a method to cover their personal risks.Meanwhile, personal value and trust were found to have no significant relationship with the purchase of life insurance among respondents in Alor Setar.It is recommended that a comprehensive study covering wider areas with larger sample sizes be included in future studies to obtain more reliable results that would enable the generalisation of finding

Strongly Regular Graphs Constructed from pp-ary Bent Functions

In this paper, we generalize the construction of strongly regular graphs in [Y. Tan et al., Strongly regular graphs associated with ternary bent functions, J. Combin.Theory Ser. A (2010), 117, 668-682] from ternary bent functions to $p$-ary bent functions, where $p$ is an odd prime. We obtain strongly regular graphs with three types of parameters. Using certain non-quadratic $p$-ary bent functions, our constructions can give rise to new strongly regular graphs for small parameters.Comment: to appear in Journal of Algebraic Combinatoric

Openness to experience as mediator of the relationship between product creativity and purchase intention

Although past studies have found a positive relationship between product creativity and purchase in-tention, little is known about the underlying process behind this relationship. The present study ad-dressed this gap by examining the role of openness to experience in the relationship between product creativity and purchase intention. Participants (88 undergraduate students) evaluated creativity of a self-nominated product and reported the extent to which they are willing to buy the product, as well as their openness to experience. Analysis showed that there was a positive relationship between product creativity and openness to experience and these two variables were significantly correlated with pur-chase intention. Furthermore, mediation analysis supported that product creativity increases purchase intension indirectly through openness to experience. The findings shed light on the mechanism of how product creativity increases purchase intention and serve as an evidence for future studies to investigate how and what aspects of product creativity that enhance individual’s sense of openness and purchase intention

Development of Hole Recognition System Using Rule-Based Technique

The effective integration of CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) is a cornerstone of automation progress. The 'islands of automation' such as CAD, CAPP (Computer Aided Process Planning) and CAM are facing the ineffective communication problem. The CAM cannot be integrated directly into CAD due to the lower level geometrical data in CAD and the higher level manufacturing data in CAM. It is important that each 'island of automation' be linked together in order to achieve the goal of integrated CAD/CAM systems. For the past decades, feature-based representation has become a basic part of research in the CAD/CAM integration. The work on feature-based modelling has developed two main approaches, namely, design by features and feature recognition. The feature recognition approach is developed to extract the manufacturing information that is recognized from the CAD database into the CAM database. The features can be used to subtract higher level manufacturing data from lower level or geometrical computer aided data. The Hole Recognition System is developed to solve the communication problem between CAD and CAM. Kappa-PC expert system is used in developing the rule of holes. In this work, the Hole Recognition System is retrieves the geometrical data from the UniGraphics (UG) CAD/CAM system indirectly. The Hole Recognition System is designed to generalise and recognise the feature from neutral format file such as Data Exchange File (DXF), Initial Graphics Exchange Specification (IGES) and Standard for the Exchange of Product Model Data (STEP). The neutral format file can be created hy CAD/CAM system such as UG, CATIA, ProEngineer, etc. For this work, the neutral data transfer standards, namely STEP is used. The STEP file is post processed by UG CAD/CAM system after the solid model has been created. A filtering program is developed to extract the geometrical data feature recognition process. The filtering program has been developed because the Kappa-PC expert system cannot read the STEP file directly. The output from the filtering program is fed to the Hole Recognition System. The rule-based technique is applied to recognise holes. There are two features, namely, blind hole and through hole to be considered. The work presented in this thesis and the Hole Recognition System developed is able to overcome the communication problem in CAD/CAM. The output from the Hole Recognition System is useful for multiple downstream manufacturing activities such as machine tool selection and cutting tool selection