557 research outputs found
Repetitive current control of two-level and interleaved three-phase PWM utility connected converters
No full textThis thesis is mainly concerned with investigations into digital repetitive current controlof two-level and interleaved utility connected PWM converters. The research ismotivated by the relatively poor performance of classical (PI) controllers when theutility voltage harmonic distortion is high. This is due to the low gain, and poordisturbance rejection of the PI controller at the utility harmonic frequencies. Repetitivefeedback controllers have the ability to track or reject periodic disturbances, such asutility harmonics, as they naturally have high gains at the utility voltage harmonicfrequencies, assuming that these frequencies do not change.Repetitive controllers (RC) are known for being sensitive to variations in systemparameters and disturbance frequency, which in practice renders them either ineffectiveor unstable. Another challenge arises from the memory requirements of RC in case ofthe absence of even harmonics, which can make its practical implementation difficultand expensive. In addition, another problem that has not been investigated extensivelyin the literature is that the effectiveness of RC is severely limited by the limitedbandwidth of the plant (the utility connected converter and its filter). Theoreticalanalysis and simulation results presented in this thesis show that RC could noteffectively reject disturbances at frequencies above the closed loop system bandwidth.The design of the converter's output filter bandwidth and the values of its componentsneed to be selected carefully, to enable RC to be used effectively.The research in this thesis focuses on investigating the practical implementation andperformance limits of two types of repetitive controllers (conventional and oddharmonics),used for current control of two-level utility connected converter with LCLoutput filter. The odd-harmonic repetitive controller halves the memory requirementand offers higher gains only at odd harmonic frequencies of interest. The overall controlscheme consists of the traditional classical tracking controller with a dual loop feedbacksystem and RC. The results indicate that the repetitive controller improves the steadystate error and the total harmonic distortion of the output current, provided that theplant's bandwidth is sufficiently large.Finally, a repetitive controller for an interleaved utility connected converter has beendesigned and investigated in this study. The interleaved converter system has higherbandwidth than the two-level converter, which improves the effectiveness of RC. Itprovides good disturbance rejection compared to classical controllers which results inlow output current THD. The RC was demonstrated to be robust despite uncertainty inutility impedance, while achieving a fast almost zero error convergence. The proposedRC has been experimentally implemented using a DSP and the results indicate that thequality of output current complies with international standards on harmonic limits andmatches simulation results obtained from the Matlab/Simulink model of the system
Dr. Jamil Jalibi: The Fragrence of Personal Relation and Research
No full textDr Jamil Jalibi (1929-2019) is a well-known writer, literary historian and critic. There are over thirty books on these genres, to his credit. He wrote a matchless History of Urdu Literature and edited a legendary literary magazine, Naya Daur, for many years. In this article, the author has remembered him, through his personal reflections. Unpublished letters of Dr Jamil Jalibi, addressed to the author, have also been produced here. These letters not only express his sentiments towards his addressee but also reflect his own personality through the words of affection and literature. Questions raised by the author are also answered by the literary genius. Issues requiring explanations have been expounded on, in the endnotes
Dr. Jamil Jalibi: The Fragrence of Personal Relation and Research
No full textDr Jamil Jalibi (1929-2019) is a well-known writer, literary historian and critic. There are over thirty books on these genres, to his credit. He wrote a matchless History of Urdu Literature and edited a legendary literary magazine, Naya Daur, for many years. In this article, the author has remembered him, through his personal reflections. Unpublished letters of Dr Jamil Jalibi, addressed to the author, have also been produced here. These letters not only express his sentiments towards his addressee but also reflect his own personality through the words of affection and literature. Questions raised by the author are also answered by the literary genius. Issues requiring explanations have been expounded on, in the endnotes
Dr. Jamil Jalibi: The Fragrence of Personal Relation and Research
No full textDr Jamil Jalibi (1929-2019) is a well-known writer, literary historian and critic. There are over thirty books on these genres, to his credit. He wrote a matchless History of Urdu Literature and edited a legendary literary magazine, Naya Daur, for many years. In this article, the author has remembered him, through his personal reflections. Unpublished letters of Dr Jamil Jalibi, addressed to the author, have also been produced here. These letters not only express his sentiments towards his addressee but also reflect his own personality through the words of affection and literature. Questions raised by the author are also answered by the literary genius. Issues requiring explanations have been expounded on, in the endnotes
Corrigendum
No full textBoyer TD, Medicis JJ, Pappas SC, Potenziano J, Jamil K. A randomized, placebo-controlled, double-blind study to confirm the reversal of hepatorenal syndrome type 1 with terlipressin: the REVERSE trial design. Open Access Journal of Clinical Trials. 2012;4:39–49.Dr Jamil’s first name was incorrectly spelt as Khuramm Jamil in the author list. The correct spelling is Khurram Jamil.Read the original articl
ڈاکٹرجمیل جالبی کا حاسئہ تحقیق : میرا جی، راشد اور میرکے خصوصی حوالےسے: SENSATION OF RESEARCH OF DR JAMIL JALBI:WITH SPECIAL REFERENCE TO MIRA.G, RASHID & MEER
No full textDr. Jamil Jalbi being an authentic reference of Urdu literature, Research and criticism has no alternative in Reseach specially. He has reviewed critically work of many literary personalites. Critical analysis of Mira.G, Rashid and Meer by Dr Jamil Jalbi are significantly known in Urdu literature. The purpose of this article is to explore Reseach expertise of Dr. Jamil Jalbi regarding Kulyat-e-Meera G, Noon-Meem Rashid-Aik Mutalia, Muhammad Taqi Meer. Author has concluded that criterion and standards of Research established by Dr. Jamil Jalbi are road map for new scholars and Researchers
ترجمےکافن اور ڈاکٹر جمیل جالبی کی ترجمہ نگاری: THE ART OF TRANSLATION AND THE RENDERINGS OF DR. JAMIL JALBI (WITH SPECIAL REFERENCE OF JANWARASTAN)
No full textTranslation and discourse analysis are the best sources of uniformity and conformity among societies and civilizations regarding meanings, ideologies, concepts and beliefs. Dr. Jamil Jalbi transforms from English language to Urdu aphoristically with same sense of meaning and context. The Researcher has critically evaluated translation of George Orwell’s novel “Animal Farm” in Urdu Language entitled “Janwarstan” by Dr. Jamil Jalbi where idioms, phrases, phrasal verbs and slangs have been transformed as Lingua Franca. The reader feels originality that is real sense of Dr. Jamil Jalbi. A sociological system allegorically has been revealed by the author and conveyed the 2nd language with contextual aspect of civilization. Political differences how run among societies are real theme and how the misuse of power handles the situations
MCL-1 localizes to sites of DNA damage and regulates DNA damage response
No full textMCL-1, a pro-survival member of the BCL-2 family, was previously shown to have functions in ATR-dependent Chk1 phosphorylation following DNA damage. To further delineate these functions, we explored possible differences in DNA damage response caused by lack of MCL-1 in mouse embryo fibroblasts (MEFs). As expected, Mcl-1(-/-) MEFs had delayed Chk1 phosphorylation following etoposide treatment, compared to wild type MEFs. However, their response to hydroxyurea, which causes a G(1)/S checkpoint response, was not significantly different. In addition, appearance of gamma-H2AX was delayed in the Mcl-1(-/-) MEFs treated with etoposide. We next investigated whether MCL-1 is present, together with other DNA damage response proteins, at the sites of DNA damage. Immunoprecipitation of etoposide-treated extracts with anti-MCL-1 antibody showed association of MCL-1 with gamma-H2AX as well as NBS1. Immunofluorescent staining for MCL-1 further showed increased co-staining of MCL-1 and NBS1 following DNA damage. By using a system that creates DNA double strand breaks at specific sites in the genome, we demonstrated that MCL-1 is recruited directly adjacent to the sites of damage. Finally, in a direct demonstration of the importance of MCL-1 in allowing proper repair of DNA damage, we found that treatment for two brief exposures to etoposide , followed by periods of recovery, which mimics the clinical situation of etoposide use, resulted in greater accumulation of chromosomal abnormalities in the MEFs that lacked MCL-1. Together, these data indicate an important role for MCL-1 in coordinating DNA damage mediated checkpoint response, and have broad implications for the importance of MCL-1 in maintenance of genome integrity.Peer reviewedfinal article publishedprotein complexchromosomesG2/McheckpointDNA repai
Developing Markers of Mechanical Dyssynchrony in Heart Failure: Implications for Research and Clinical Practice in Cardiac Resynchronisation Therapy
Get PDFThis thesis studies techniques for maximising the effects of Cardiac
Resynchronisation Therapy (CRT) which is a modern therapy for chronic heart
failure.
The ability of echocardiographic parameters of mechanical dyssynchrony to identify
suitable candidate patients for CRT, and subsequently to optimise the interventricular
delay, is disputed. In this study, I initially perform a systematic review to clarify the
nature and extent of this problem. I then perform detailed mathematical simulations to
understand what is feasible in an ideal setting.
I then evaluate the realistic potential of several non-invasive approaches of optimising
CRT devices by formal evaluation head-to-head. A fundamental requirement for any
marker in optimisation of CRT devices, or in selection of patients for implantation, is
that the marker must be reproducible and must change when the amount of
dyssynchrony changes.
I perform detailed experiments in patients where I interrogated a panel of
echocardiographic parameters to answer the questions relating to the sensitivity of
each parameter and looked at methods to improve this. I look at the effect of
spontaneous variability, and the impact on each echocardiographic method including
3D echocardiography, tissue Doppler imaging and pulsed Doppler techniques
including velocity time integrals and pre-ejection times.
Finally, I perform an invasive study of the beat to beat physiological changes which
occur after intra cardiac timings are altered, to evaluate alternative approaches to
changes in cardiac performance that might be easier to automate
The quantification of cardiac function
Get PDFQuantification of cardiac function is a crucial part of diagnosis, prognosis and ongoing management for many patients with heart disease. Clinical examination is an insensitive marker of cardiac dysfunction, resulting in echocardiography being an in-demand gold-standard test.
In recent years, there has been a revolution in point-of-care echocardiography, with the availability of affordable equipment with limited functionality capable of obtaining 2-dimensional pictures and limited measurements. This equipment is often used by non-specialists who make visual gradings or estimates of cardiac function.
In this thesis I showed that this approach is potentially flawed, in that operators find it difficult to agree with themselves (and consequently with each other) when reviewing the same images. Even when used as a “gatekeeper” test to differentiate normal from abnormal in triage for further testing, this thesis shows that operators frequently disagree with their original judgement when seeing the same images again on the question of normal versus abnormal.
I developed software to allow humans to make bias-resistant replicate measurements from Doppler traces blinded to their previous results and used this to investigate how operators make measurements of cardiac function and aortic stenosis. I show that the mechanism of disagreement in tracing velocity time integral is the difficulty in tracing steep slopes at the beginning and end of the trace. I also show that one of the reasons why dimensionless index is useful is that it is the ratio of correlated errors: operators tend to be systematic “over-readers” or “under-readers”.
Tissue Doppler imaging can be used to assess cardiac function, and because it encodes systolic and diastolic information efficiently, is ideal for automated image analysis. In this thesis I show that current clinical protocols capture most of the variability that arises on a beat to beat basis, but that subtle differences in optimal probe placement (unrecognised by an operator) are an unpredictable and potentially significant source of variability. Because beat to beat variation arises early on, extended multi-beat analysis is capable of generating high-precision measurements, which may be of value in research.
I go on to develop an image analysis algorithm to extract measurements from tissue Doppler traces, testing it against human operators. I show that the system can make measurements of systolic and diastolic function with less bias then humans show between each other. This system may be useful to allow rapid high-precision bias-resistant measurements of cardiac function.Open Acces
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