On A New Approach to Model Reference Adaptive Control

The objective of adaptive control is to design a controller that can adjust its behaviour to tolerate uncertain or time-varying parameters. An adaptive controller typically consists of a linear time-invariant (LTI) compensator together with a tuning mechanism which adjusts the compensator parameters and yields a nonlinear controller. Because of the nonlinearity, the transient closed-loop behaviour is often poor and the control signal may become unduly large. Although the initial objective of adaptive control was to deal with time-varying plant parameters, most classical adaptive controllers cannot handle rapidly changing parameters. Recently, the use of a linear periodic (LP) controller has been proposed as a new approach in the field of model reference adaptive control [1]. In this new approach, instead of estimating plant parameters, the “ideal control signal” (what the control signal would be if the plant parameters and states were measurable) is estimated. The resulting controller has a number of desirable features: (1) it handles rapid changes in the plant parameters, (2) it provides nice transient behaviour of the closed-loop system, (3) it guarantees that the effect of the initial conditions declines to zero exponentially, and (4) it generates control signals which are modest in size. Although the linear periodic controller (LPC) has the above advantages, it has some imperfections. In order to achieve the desirable features, a rapidly varying control signal and a small sampling period are used. The rapidly time-varying control signal requires fast actuators which may not be practical. The second weakness of the LPC [1] is poor noise rejection behaviour. The small sampling period results in large controller gains and correspondingly poor noise sensitivity, since there is a clear trade-off between tracking and noise tolerance. As the last drawback, this controller requires knowledge of the exact plant relative degree. Here we extend this work in several directions: (i) In [1], the infinity-norm is used to measure the signal size. Here we redesign the controller to yield a new version which provides comparable results when the more common 2-norm is used to measure signal size, (ii) A key drawback of the controller of [1] is that the control signal moves rapidly. Here we redesign the control law to significantly alleviate this problem, (iii) The redesigned controller can handle large parameter variation and in the case that the sign of high frequency gain is known, the closed-loop system is remarkably noise-tolerant, (iv) We prove that in an important special case, we can replace the requirement of knowledge of the exact relative degree with that of an upper bound on the relative degree, at least from the point of view of providing stability, and (v) A number of approaches to improve the noise behaviour of the controller are presented. Reference: [1] D. E. Miller, “A New Approach to Model Reference Adaptive Control”, IEEE Transaction on Automatic Control, Vol. 48, No. 5, pages 743-756, May 2003

The change in attitude and knowledge of health care personnel and general population following trainings provided during integration of mental health in Primary Health Care in Iran: a systematic review

<p>Abstract</p> <p>Background</p> <p>Mental health has been integrated in the primary health care program in small cities and villages of Iran in a national level since the late 1980s. We performed a systematic review of literature to investigate the effect of education on change in attitude and knowledge of mental health care providers and the population covered in the program during the recent two decades in Iran.</p> <p>Methods</p> <p>Electronic bibliographic databases including Pubmed, PsycINFO and EMBase as well as the main Iranian databases (Scientific Information Database, IranMedex, IranPsych, and IranDoc) were searched. Additionally, hand searching, personal contacts and tracking of reference lists were performed. All of the studies which compared the attitude and knowledge of the related population before and after an educational intervention were recruited.</p> <p>Results</p> <p>Six articles met the inclusion criteria and entered the review. All of these studies showed an improvement in the attitude and knowledge of the studied population. Although the studies were different in many respects, a meta-analysis on the two more similar studies showed a significant effect of training on long term improvement of the knowledge and attitude of the population.</p> <p>Conclusion</p> <p>A short term training improved knowledge and attitude of the population and health personnel immediately after the intervention. There is also evidence for a long term change in the attitude and knowledge of general population after short term training.</p

Case finding in integration of Mental Health Services into Primary Health Care System: systematic review of the studies conducted in Iran in recent two decades

"n "n "nObjective: This study aims at conducting a systematic review of the researches performed to determine case finding rates throughout the integration of Mental Health Services into PHC over recent twenty years . "n "n "nMethod : Through electronic search, major national and international databases including Pubmed, PsychInfo, and EMBase were investigated. All original studies and researches in Persian or English, which had described psychiatric case finding in the PHC, classified as severe and mild mental disorders,epilepsy, mental retardation, and other disorders, were included in the study and were qualitatively assessed. Subsequent to data extraction, heterogeneity test was carried out on all of the studies and each subgroup. Meta-analysis was not applicable as a result of the wide range and heterogeneity of the reported results. "n "n "nResults: Overall, ten studies were included. Case finding rate ranged from 0.07 to 2.04 per thousand for severe mental disorders, 0.5 to 7.6 per thousand for mild mental disorders, 0.5 to 3.9 per thousand for epilepsy, and 0.64 to 3.94 per thousand for mental retardation. "n "n "nConclusion: Case finding rates reported in the selected studies are highly different from the prevalence of the disorders throughout the&nbsp; ountry. It seems that the program has been functioning more effectively in case of some of the disorders such as mental retardation, while it has been less efficient in finding mild mental disorder cases. These results reflect the fact that despite its partial achievements in the field of case finding, the integration program is still far from the desirable rates and there is need for revision of its content of the integration program especially screening and diagnostic tools, training contents, and implementation methods

Prevalence of psychiatric disorders in Iran: A systematic review

"n Objective:Taking the diversity of the methodologies applied in prevalence studies of psychiatric disorders in Iran and their heterogeneous results into consideration, there seems to be need for a systematic review in order to compile the findings and seek appropriate recommendations for future studies. This study aims at systematically identifying studies conducted in Iran describing the prevalence of psychiatric disorders in general population, and to summarize the findings of these studies. "n "n Method:To identify the relevant studies, several databases including Pubmed Medline, ISI Web of Science, PsychINFO, CINAHL, EMBASE, Irandoc, IranPsych, IranMedex, Scientific Information Database as well as reference lists of the accessed documents, unpublished reports, conference proceedings and dissertations were searched. In the next step, the original studies which contained an estimation of prevalence of "any psychiatric disorder" (overall prevalence) among a sample of general population in the country were selected. This was followed by data extraction, presentation of the results, quality assessment and quantitative pooling of estimated rates of prevalence of psychiatric disorders. Results:A total number of 35 studies were included. Estimations provided for prevalence rates in different groups illustrate diversity and heterogeneity; the rates varied in the range of 1.9-58.8%. Most of the studies had assessed the point prevalence of the disorders conducted using screening instruments. The median point prevalence has been reported to be 28.70% in screening studies, and 18.60% in studies using diagnostic interviews. Pooled estimates obtained through meta-analysis for screening and diagnostic studies were 29.1% and 21.9%,respectively. The results of the studies which have used diagnostic interviews as their data collection tool showed less heterogeneity than the ones using screening instruments. In quality assessment of the studies, only one third proved to be of high quality. "nConclusion: Even though the pooled rates for prevalence of psychiatric disorders are comparable to the rates in many other countries, the most important finding of this study is the diversity of the prevalence rates among different communities in Iran. This diversity does not seem to be attributed solely to the different time frames and geographical locations of the studies. It might also have resulted from differences in methodologies (e.g., using different tools), study procedures and study quality