State feedback linearized model for phase-controlled series-parallel resonant converters

This paper proposes a linearized large-signal state space model for phase-controlled series-parallel resonant converter. The model combines multiple-frequency and average state-space modeling techniques to generate a universal model with DC state variables that are easier to control compared to the fast resonant tank dynamics. In order to perform linearization, the proposed model utilizes a state feedback scheme from output filter inductor current. The model also serves as a tool for large signal prediction/estimation of converter state variables. The model accuracy was verified by comparing with a detailed switching model of the converter built in MATLAB simulation environment

Psychosocial Stressors and Major Depression, Schizophrenia, and Schizophreniform Disorder

This study explored the relationship between the severity and types of psychosocial stressors and three major mental disorders. The data were derived from the field trials of the third edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-III), in which over 12,000 patients from all over the country were evaluated by over 500 clinicians. Two hundred forty-seven patients with Major Depression and 247 with Schizophrenia were randomly selected for this study, along with all 112 patients given the diagnosis of Schizophreniform Disorder, a disorder similar to Schizophrenia except for its brief duration. The number of psychosocial stressors recorded by the evaluating clinician for each subject was examined, and each stressor was classified according to whether it represented an entrance into or exit from the social field of the subject, whether or not it was desirable, whether or not its occurrence had been under the control of the subject, the number of Life Change Units it entailed, and what area of the subject's life is affected. These variables were then compared across diagnostic groups, for individuals with and without associated Personality Disorders. In addition, for each diagnostic group, the relationship between the subjects' highest mean level of adaptive functioning and the mean severity of their psychosocial stressors was examined, using the multiaxial system of DSM-III. Major findings that replicated those reported in the literature include that a greater proportion of individuals with Major Depression were reported to have experienced a greater number of stressors, undesirable events, entrances, and uncontrollable events, than individuals with Schizophrenia. Significant new findings include that, for Schizophrenia, the highest level of adaptive functioning in the past year and level of severity of stressors experienced prior to episode onset are positively correlated, while for Major Depression these variables are negatively correlated. The results for Schizophreniform Disorder are equivocal, with similar results to Major Depression for some stressor dimensions, and midway between the other groups on others. The implications for social work practice of these findings and further study of life events are great, for primary, secondary, and tertiary prevention of mental illness

Comparison between flying capacitor and modular multilevel inverter

The paper describes the operational principle of flying capacitor and modular multilevel inverters. The detailed discussions of dc link capacitors voltage balancing methods for both inverters are given in order to enable fair comparison. The causes of dc link capacitors voltage imbalance in flying capacitor multilevel inverter with more than three levels are highlighted. Computer simulation is used to compare the performance of both inverters under several operating conditions

Comparison between two VSC-HVDC transmission systems technologies : modular and neutral point clamped multilevel converter

The paper presents a detail comparison between two voltage source converter high voltage dc transmission systems, the first is based on neutral point-clamped (also known as HVDC-Light) and the second is based on innovative modular multilevel converter (known as HVDC-Plus). The comparison focuses on the reliability issues of both technologies such as fault ride-through capability and control flexibility. To address these issues, neutral point-clamped and three-level modular converters are considered in both stations of the dc transmission system, and several operating conditions are considered, including, symmetrical and asymmetrical faults. Computer simulation in Matlab-Simulink environment has been used to confirm the validity of the results

The impacts of informality on enterprise innovation, survival and performance: Some evidence from Pakistan

The aim of this paper is to evaluate the relationship between informality, innovation and firm survival. To do so, a study of a cluster of electrical fittings firms in Pakistan is reported. Reporting bivariate and multivariate probit models to analyze two surveys conducted between 2008 and 2017, the finding is that there is a significant relationship between informality and the extent of innovation, firm survival and firm performance. Informality has an adverse negative effect on firm-level innovation, firm survival and firm performance. Given that formal enterprises in this cluster are better performing in terms of innovation, survival and employment growth than informal businesses, the paper concludes by discussing the theoretical, policy and research implications

Environmental data management at Fernald

FERMCO supports DOE`s ongoing initiatives for the continuous improvement of site restoration through the development and application of innovative technologies. A major thrust of FERMCO`s efforts has been the enhancement of environmental data management technology for the site. The understanding of environmental data is the fundamental basis for determining the need for environmental restoration, developing and comparing remedial alternatives, and reaching a decision on how to clean up a site. Environmental data management at Fernald is being focused on two major objectives: to improve the efficiency of the data management process, and to provide a better understanding of the meaning of the data at the earliest possible time. Environmental data at Fernald is typically a soil or groundwater sample collected by one of the field geologists. These samples are then shipped to one or more laboratories for analysis. After the analyses are returned from the laboratories the data are reviewed and qualified for usability. The data are then used by environmental professionals for determining nature and extent of contamination. Additionally, hazardous waste materials whether generated during production or during cleanup, may be sampled to characterize the waste before shipment or treatment. The data management process, which uses four major software systems, is presented graphically

The response to high magnetic fields of the vacuum phototriodes for the compact muon solenoid endcap electromagnetic calorimeter

The endcap electromagnetic calorimeter of the Compact Muon Solenoid (CMS) detects particles with the dense fast scintillator lead tungstate (PbWO4). Due to the low light yield of this scintillator photodetectors with internal gain are required. Silicon avalanche photodiodes cannot be used in the endcap region due to the intense neutron flux. Following an extensive R&D programme 26 mm diameter single-stage photomultipliers (vacuum phototriodes) have been chosen as the photodetector in the endcap region. The first 1400 production devices are currently being evaluated following recent tests of a pre-production batch of 500 tubes. Tubes passing our acceptance tests have responses, averaged over the angular acceptance of the endcap calorimeter, corresponding to the range 20 to 55 electrons per MeV deposited in PbWO4. These phototriodes operate, with a typical gain of 10, in magnetic fields up to 4T.PPARC, EC(INTAS-CERN scheme 99-424

Randomized Clinical-Trial of Manipulative Therapy and Physiotherapy for Persistent Back and Neck Complaints - Results of One Year Follow-Up

Objective - To compare the effectiveness of manipulative therapy, physiotherapy, treatment by the general practitioner, and placebo therapy in patients with persistent non-specific back and neck complaints. Design - Randomised clinical trial. Setting-Primary health care in the Netherlands. Patients-256 patients with non-specific back and neck complaints of at least six weeks' duration who had not received physiotherapy or manipulative therapy in the past two years. Interventions - At the discretion of the manipulative therapists, physiotherapists, and general practitioners. Physiotherapy consisted of exercises, massage, and physical therapy (heat, electrotherapy, ultrasound, shortwave diathermy). Manipulative therapy consisted of manipulation and mobilisation of the spine. Treatment by general practitioners consisted of drugs (for example, analgesics), advice about posture, home exercises, and (bed)rest. Placebo treatment consisted of detuned shortwave diathermy (10 minutes) and detuned ultrasound (10 minutes). Main outcome measures - Changes in severity of the main complaint and limitation of physical functioning measured on 10 point scales by a blinded research assistant and global perceived effect measured on a 6 point scale by the patients. Results - Many patients in the general practitioner and placebo groups received other treatment during follow up. Improvement in the main complaint was larger with manipulative therapy (4·5) than with physiotherapy (3·8) after 12 months' follow up (difference 0·9; 95% confidence interval 0·1 to 1·7). Manipulative therapy also gave larger improvements in physical functioning (difference 0·6; -0·1 to 1·3). The global perceived effect after six and 12 months' follow up was similar for both treatments. Conclusions - Manipulative therapy and physiotherapy are better than general practitioner and placebo treatment. Furthermore, manipulative therapy is slightly better than physiotherapy after 12 months