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Search Results: 1 - 10 of 9542 matches for " Joe-Kai Tsay "
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Computational Security Analysis of the UMTS and LTE Authentication and Key Agreement Protocols
Joe-Kai Tsay,Stig Mj?lsnes
Computer Science , 2012,
Abstract: We present a computational security analysis of the Authentication and Key Agreement (AKA) protocols for both Long-Term Evolution (LTE) and Universal Mobile Telecommunications System (UMTS). This work constitutes the first security analysis of LTE AKA to date and the first computationally sound analysis of UMTS AKA. Our work is the first formal analysis to consider messages that are sent in the core network, where we take into account details of the carrying protocol (i.e., MAP or Diameter) and of the mechanism for secure transport (i.e., MAPsec/TCAPsec or IPsec ESP). Moreover, we report on a deficiency in the protocol specifications of UMTS AKA and LTE AKA and the specifications of the core network security (called network domain security), which may enable efficient attacks. The vulnerability allows an inside attacker not only to impersonate an honest protocol participant during a run of the protocol but also to subsequently use wireless services on his behalf. UMTS AKA run over MAP with MAPsec seems vulnerable in the most straight-forward application of the attack. On the other hand, our analysis shows that UMTS and LTE AKA over Diameter/IPsec and UMTS AKA over MAP/TCAPsec (with sufficiently long session identifiers) computationally satisfy intended authentication properties as well as some key secrecy properties, assuming that the used primitives meet standard cryptographic assumptions.
Informing patients of familial diabetes mellitus risk: How do they respond? A cross-sectional survey
Nadeem Qureshi, Joe Kai
BMC Health Services Research , 2008, DOI: 10.1186/1472-6963-8-37
Abstract: We conducted an analysis of the National Health Styles 2004 mail survey. All non-diabetic participants who responded to the question of whether their doctor had or had not informed them of their familial DM risk (n = 3,323) were compared for their risk-reducing behaviour and attitude to DM risk.Forty-one percent (n = 616) of the question responders that had DM family histories were informed by their doctors of their familial risk; the chance of being informed increased with the number of relatives that had the disease. Members of the informed group were more likely than those in the non-informed group to report lifestyle changes to prevent DM (odds ratio [OR] 4.3, 95% confidence interval [CI] 3.5–5.2) and being tested for DM (OR 2.9, 95% CI 2.4–3.6), although no significant improvement occurred in their U.S.-recommended exercise activity (OR 0.9, 95% CI 0.7–1.1). Overall, informed responders recognised both their familial and personal DM risk; most discussed diabetes with their family (69%), though less so with friends (42%); however, 44% of them still did not consider themselves to be at risk.Responders who were informed by their doctors of being at familial DM risk reported greater incidences of lifestyle changes, DM screening, and awareness of risk than non-informed responders. Doctors were more likely to inform patients with stronger DM family histories. Identifying this higher risk group, either in isolation or in combination with other recognised risk factors, offers doctors the opportunity to target limited health promotion resources efficiently for primary DM prevention.Diabetes mellitus (DM) rates continue to rise and are predicted to reach epidemic proportions among the U.S. population within the next 50 years [1]. This dramatic rise is a global phenomenon. Recognized, modifiable risk factors for type 2 DM include a diet high in fat and sugar, obesity, and lack of exercise. Non-modifiable risk factors include age, ethnicity, and family history. A growing b
A Directional Diffusion Algorithm for Inpainting
Jan Deriu,Rolf Jagerman,Kai-En Tsay
Computer Science , 2015,
Abstract: The problem of inpainting involves reconstructing the missing areas of an image. Inpainting has many applications, such as reconstructing old damaged photographs or removing obfuscations from images. In this paper we present the directional diffusion algorithm for inpainting. Typical diffusion algorithms are bad at propagating edges from the image into the unknown masked regions. The directional diffusion algorithm improves on the regular diffusion algorithm by reconstructing edges more accurately. It scores better than regular diffusion when reconstructing images that are obfuscated by a text mask.
Adaptive Piecewise Linear Controller for Servo Mechanical Control Systems  [PDF]
Tain-Sou Tsay
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.15013

In this paper, an adaptive piecewise linear control scheme is proposed for improving the performance and response time of servo mechanical control systems. It is a gain stabilized control technique. No large phase lead compensations or pole zero cancellations are needed for performance improvement. Large gain is used for large tracking error to get fast response. Small gain is used between large and small tracking error for good performance. Large gain is used again for small tracking error to cope with disturbance. It gives an almost command independent response. It can speed up the rise time while keeping robustness unchanged. The proposed control scheme is applied to a servo system with large time lag and a complicated electro-hydraulic velocity/position servo system. Time responses show that the proposed method gives significant improvements for response time and performance.

Imparting carrier status results detected by universal newborn screening for sickle cell and cystic fibrosis in England: a qualitative study of current practice and policy challenges
Hilda Parker, Nadeem Qureshi, Fiona Ulph, Joe Kai
BMC Health Services Research , 2007, DOI: 10.1186/1472-6963-7-203
Abstract: Thematic analysis of semi-structured interviews with Child Health Coordinators from all English Health Regions.Diverse methods for imparting carrier results, both within and between regions, and within and between conditions, were being implemented or planned. Models ranged from result by letter to in-person communication during a home visit. Non-specialists were considered the best placed professionals to give results and a similar approach for both conditions was emphasised. While national guidance has influenced choice of models, other factors contributed such as existing service structures and lack of funding. Challenges included uncertainty about guidance specifying face to face notification; how best to balance allaying parental anxiety by using familiar non-specialist health professionals with concerns about practitioner competence; and extent of information parents should be given. Inadequate consideration of resource and service workload was seen as the main policy obstacle. Clarification of existing guidance; more specific protocols to ensure consistent countrywide practice; integration of the two programmes; and 'normalising' carrier status were suggested as improvements.Differing models for communicating carrier results raise concerns about equity and clinical governance. However, this variation provides opportunity for evaluation. Timely and more detailed guidance on protocols with clarification of existing recommendations is needed.Part of the newborn bloodspot programme [1], universal newborn screening for sickle cell disorders (SCD) is now fully implemented across England [2] and will be for cystic fibrosis (CF) [3] by mid-2007. In addition, a linked antenatal haemoglobin disorder (HD) screening programme is being rolled out; universal in areas with a high prevalence and selective in low prevalence areas. High prevalence areas are those where sickle cell disease is estimated to affect more than 1.5 per 10,000 pregnancies and low prevalence those with
Availability and Quality of Coronary Heart Disease Family History in Primary Care Medical Records: Implications for Cardiovascular Risk Assessment
Paula Dhiman, Joe Kai, Laura Horsfall, Kate Walters, Nadeem Qureshi
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0081998
Abstract: Background The potential to use data on family history of premature disease to assess disease risk is increasingly recognised, particularly in scoring risk for coronary heart disease (CHD). However the quality of family health information in primary care records is unclear. Aim To assess the availability and quality of family history of CHD documented in electronic primary care records Design Cross-sectional study Setting 537 UK family practices contributing to The Health Improvement Network database. Method Data were obtained from patients aged 20 years or more, registered with their current practice between 1st January 1998 and 31st December 2008, for at least one year. The availability and quality of recorded CHD family history was assessed using multilevel logistic and ordinal logistic regression respectively. Results In a cross-section of 1,504,535 patients, 19% had a positive or negative family history of CHD recorded. Multilevel logistic regression showed patients aged 50–59 had higher odds of having their family history recorded compared to those aged 20–29 (OR:1.23 (1.21 to 1.25)), however most deprived patients had lower odds compared to those least deprived (OR: 0.86 (0.85 to 0.88)). Of the 140,058 patients with a positive family history recorded (9% of total cohort), age of onset was available in 45%; with data specifying both age of onset and relative affected available in only 11% of records. Multilevel ordinal logistic regression confirmed no statistical association between the quality of family history recording and age, gender, deprivation and year of registration. Conclusion Family history of CHD is documented in a small proportion of primary care records; and where positive family history is documented the details are insufficient to assess familial risk or populate cardiovascular risk assessment tools. Data capture needs to be improved particularly for more disadvantaged patients who may be most likely to benefit from CHD risk assessment.
Are the ASISA Standards with Respect to Unit Trust Classification Representative of Homogeneous Risk Classes?  [PDF]
Joe Kainja
Journal of Financial Risk Management (JFRM) , 2016, DOI: 10.4236/jfrm.2016.52008
Abstract: We examine the information content of South African (SA) equity unit trusts to investigate whether risk is heterogeneous between investment objective groups and homogeneous within groups because those characteristics are vital to proper investment decision making. We find risk differences within SA equity groups especially in the Equity-General and Equity-Growth. However, in the other categories, the systematic risk differences depended on the choice of benchmark. Those risk differences may have significant implications for investors. Examination of between-group risk revealed that not all the equity categories were heterogeneous. We also find that the choice of benchmark is critical when measuring and comparing performance characteristics of funds.
Automatic Regulation Time Series for Industry Processes
Tain-Sou Tsay
Mathematical Problems in Engineering , 2012, DOI: 10.1155/2012/710690
Abstract: A nonlinear digital control scheme is proposed for analyses and designs of stable industry processes. It is derived from the converging characteristic of a specified numerical time series. The ratios of neighbourhoods of the series are formulated as a function of the output of the plant and the reference input command and will be converted to be unities after the output has tracked the reference input command. Lead compensations are also found by another numerical time series to speed up the system responses on the online adjusting manner. A servosystem, a time-delay system, a high-order system, a very-high-order system, and a 2 × 2 multivariable aircraft gas turbine engine are used to illustrate effectiveness of the proposed nonlinear digital controller. Comparisons with other conventional methods are also made.
Limit Cycle Predictions of Nonlinear Multivariable Feedback Control Systems with Large Transportation Lags
Tain-Sou Tsay
Journal of Control Science and Engineering , 2011, DOI: 10.1155/2011/169848
Abstract: A practical method is developed for limit-cycle predictions in the nonlinear multivariable feedback control systems with large transportation lags. All nonlinear elements considered are linear independent. It needs only to check maximal or minimal frequency points of root loci of equivalent gains for finding a stable limit-cycle. This reduces the computation effort dramatically. The information for stable limit-cycle checking can be shown in the parameter plane also. Sinusoidal input describing functions with fundamental components are used to find equivalent gains of nonlinearities. The proposed method is illustrated by a simple numerical example and applied to one 2×2 and two 3×3 complicated nonlinear multivariable feedback control systems. Considered systems have large transportation lags. Digital simulation verifications give calculated results provide accurate limit cycle predictions of considered systems. Comparisons are made also with other methods in the current literature.
Data Preprocessing Circuit Designs and Analyses for Subsonic Cruise Missile Infrared Image Seeker
Tain-Sou Tsay
The Open Automation and Control Systems Journal , 2008, DOI: 10.2174/1874444300801010014]
Abstract: In this literature, a data pre-processing circuit designs and analyses for an infrared image seeker of a subsonic cruise missile are proposed. The flight speed of the missile is 250m/s. Therefore, automatic contrast control and automatic brightness control are usually needed to keep wanted contrast and brightness for best image properties in target recognition and tracking; especially for the missile at the terminal approaching phase to prevent signal saturation. Signal saturation implies target lost. The major parameters of imaging systems for contrast and brightness controls include average, maximum and minimum of gray level of the whole picture in the sampling interval. Therefore, the overall system is a complicated nonlinear sampled-data control system. It is difficult to describe, analyze and design the system. In this literature, the overall system is first decomposed into two linearized sampled-data control systems to get needed loop compensations, and verified by a special range-dependent testing signal to the overall system secondly. The controlled system is further verified by a thermal plate and real flight testing. Testing results give the proposed method can provide effective way to analyze and design the considered system.
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