A Role-Based Service Level NFC Ecosystem Model

Near Field Communication (NFC) is a short range wireless communication technology allowing to communicate mobile devices within close proximity. It provides opportunity for service providers to offer various value added services to customers. NFC technology allows the usage of wide range of applications and eliminates the obligation to carry additional components other than the mobile device such as credit or payment cards, tickets, identification cards or keys. Despite its technological advantages over alternative ones, the NFC business ecosystems and services are yet to take off. The problems mainly arise with the business issues triggered by different and mostly conflicting needs of many actors in the ecosystem and several additional technical issues. In this study, by adopting a role-based service ecosystem modeling, we propose an NFC ecosystem model which perfectly specifies the roles in the ecosystem, and defines set of activities for each role, and communication structure. We analyzed NFC ecosystem in three phases as pre-installation, installation, and service usage. We have defined the activities and communication structure in the first two phases, and finally investigated the service usage phase in three different operating modes of NFC. After giving the details of the proposed ecosystem model, two use cases are given to validate the developed ecosystem model. We complete our study by discussing the requirement satisfaction.     

A mathematical characterization and analysis of a feedforward circuit for CDMA applications

Feedforward is known to be one of the best methods for power amplifier linearization due to its superior linearization performance albeit with relatively poor power efficiency. Here we present the derived closed-form expressions, which relate the main channel power and distortion products at the output of a simple feedforward circuitry to the circuit parameters. Consequently, a mathematical handy tool is achieved toward specifying the circuit parameters rapidly for optimum linearity performance and efficiency. The main and error amplifiers used in the feedforward are assumed to have a third-order AM/AM nonlinearity. The derived expressions are verified by simulation. The conditions for the validity of the model choice are highlighted. For the matched and lossless case, a compact relationship is obtained, which clearly demonstrates the tradeoff between nonlinearities of main and error amplifier for a given system linearity and output power. Delay mismatch is also included in the analysis.     

Ozone Consumption in Natural Waters: Effects of Background Organic Matter,pH and Carbonate Species

It was demonstrated that, in natural waters, the overall kineticsof dissolved ozone consumption can be characterized by the “specific ozone utilization rate”, w[time ^?1]. The dependency of w on the chemical quality of the raw water was analyzed. And, the variation of w values measured in different water samples was explained in terms of the pH, alkalinity, and total organic carbon content of the solution matrix.