S.H. Khan

Timestamp authentication protocol for remote monitoring in eHealth

Remote monitoring is fundamental in eHealth and introducing mobile devices in the remote monitoring process can provide additional benefits to both patients and medical personnel. For mobile remote monitoring systems to be successful, however, the authentication process must be in place to prevent the misuse of the system. In this paper we analyse the use of timestamps in the authentication process, showing many advantages timestamps have over other authentication methods. The paper presents the design principles for timestamp based authentication protocols in remote monitoring systems and proposes a specific protocol to implement such a system.

Modeling in measurement and instrumentation: an overview

Abstract The paper presents an overview of the nature and application of models in measurement and instrumentation science and technology. It considers the nature of models and the modeling process as well as the role of computers. It reviews representation schemes and models appropriate to various levels of abstraction. It concludes by a consideration of applications of models to design and in model-based measurement.

Privacy in Mobile Web Services eHealth

There are many advantages to deploying mobile devices in eHealth systems. However; security is still an issue: in particular authentication and user privacy. In this paper we propose a novel architecture that integrates 3GPP UMTS mobile technology with Web services. This will help address authentication and privacy concern within eHealth environment. The architecture makes use of the generic authentication architecture from the 3GPP and the single sign-on system to authenticate mobile users to a health authentication server to give access to various eHealth service providers. The platform for Privacy Preferences Project is thus used to manage privacy in the system

Investigation of the effects of design parameters on output characteristics of capacitive angular displacement sensors by finite element field modelling

The effects of design parameters on performance characteristics of a capacitive angular displacement sensor used in limited angle torque motors are investigated. This is done by 2D finite element modelling and computation of electrostatic fields in the complex geometry of the sensor. Results are presented in terms of sensors output characteristic showing the effects of some of its material and geometric parameters. The output characteristic investigated is the variation of sensor output voltage V with angular position /spl theta/ of the motor rotor, V=f(/spl theta/). The design parameters used comprise permittivities of various dielectric materials and angular width w/sub 1/ of the sensor.

Finite element modelling of electrostatic fields in process tomography capacitive electrode systems for flow response evaluation

Various aspects and results of 2-D finite element (FE) modeling of electrostatic fields in 12-electrode capacitive systems for two-phase flow imaging are described. The capacitive technique relies on changes in capacitances between electrodes (mounted on the outer surface of the flow pipe) due to the change in permittivities of flow components. The measured capacitances between various electrode pairs and the field computation data are used to reconstruct the cross sectional image of the flow components. FE modeling of the electric field is necessary to optimize design variables and evaluate the system response to various flow regimes, likely to be encountered in practice. Results are presented in terms of normalized capacitances for various flow regimes. The effects of key geometric parameters of the electrode system are presented and analyzed. >

A Web Services Shopping Mall for Mobile Users

In this paper we present a platform for the direct consumption of Web services by a Mobile Station. We give an architectural solution where Mobile Operators play the role of Trusted Third Parties supplying service credentials that allow a co-located 3GPP network application function and liberty-enabled identity provider entity to implement a controlled shopping mall service to mobile stations from multiple trust domains. We consider both the protocol and the structure and syntax of the various tokens required to minimise service latency over the bandwidth and performance constrained mobile system, whilst providing adequate security services to protect against the perceived threat model. To validate our proposal we have developed code to create a Web service test scenario utilising readily available J2ME, Java Card, J2SE and J2EE platforms, Web services tools from Apache, the KTool-Bar emulator from Sun, and the JCOPS suite of tools for Java Card applet development

Methods of calculation of magnetic fields and static characteristics of linear step motors for control rod drives of nuclear reactors

The performance of linear step motors (LSM) which are now being developed for control rod drives (CRD) in nuclear reactors is governed by their static characteristics. The reliability of control rod drive mechanisms and the safety of the reactor depend on reliable performance of these motors. This paper describes methods of calculation of magnetic fields and static characteristics of LSM. Two methods have been developed approximate and accurate. The first method less computationally intensive could be used for small currents and weak iron saturation, the second based on accurate field modeling takes into account saturation effects which considerably affect motor performance.

Unbiased, optimal, and in-betweens: the trade-off in discrete finite impulse response filtering

In this survey, the authors examine the trade-off between the unbiased, optimal, and in-between solutions in finite impulse response (FIR) filtering. Specifically, they refer to linear discrete real-time invariant state-space models with zero mean noise sources having arbitrary covariances (not obligatorily delta shaped) and distributions (not obligatorily Gaussian). They systematically analyse the following batch filtering algorithms: unbiased FIR (UFIR) subject to the unbiasedness condition, optimal FIR (OFIR) which minimises the mean square error (MSE), OFIR with embedded unbiasedness (EU) which minimises the MSE subject to the unbiasedness constraint, and optimal UFIR (OUFIR) which minimises the MSE in the UFIR estimate. Based on extensive investigations of the polynomial and harmonic models, the authors show that the OFIR-EU and OUFIR filters have higher immunity against errors in the noise statistics and better robustness against temporary model uncertainties than the OFIR and Kalman filters.

Computation of 3-D Magnetic Field Distribution in Long-Lifetime Electromagnetic Actuators

This paper involves the computation of 3-D magnetic fields in high-performance, long-lifetime solenoid actuators by finite-element (FE) modeling. Operating at frequencies between 150 and 300 Hz, these actuators are unique in terms of the large force they produce (8-15 N) and their very long lifetime (over five billion continuous duty cycles). Their magnetic circuit typically operates at saturation and, because of the compact dimensions, the 3-D nature of the field distribution needs to be taken into account for their design. Results are presented in terms of the effects of design parameters on saturation and force calculation

General Unbiased FIR Filter With Applications to GPS-Based Steering of Oscillator Frequency

The general unbiased finite-impulse response (UFIR) filter proposed in this brief has important structural advantages against its basic predecessor. It can be applied to systems with or without the control input. We derive this filter in a batch form and then design its fast iterative Kalman-like algorithm using recursions. The iterative UFIR algorithm proposed is applied to the three-state polynomial model which is basic in clock synchronization. We test it by the global positioning system-based frequency steering of an oven-controlled crystal oscillator. Better robustness and higher accuracy of the UFIR filter against the Kalman filter are shown experimentally.