122 research outputs found
Improved Understanding of Standing Waves in Single Layer Coils and Elegant Methods to Estimate Transformer Winding Parameters
No full textAnalyzing the effect of impulse voltages (like lightning, switching) on transformer winding has occupied centerstage in core electrical engineering research for over a century. These investigations gather great significance and relevance as it eventually governs the design of insulation in the winding. Notwithstanding the colossal contribution this domain has witnessed from stalwarts in the past century, a closer scrutiny surprisingly reveals that there still exists tiny grey areas that demands attention. Pursuing this line of thought, the first part of this thesis aims to clearly describe what this grey area is and resolving it would provide a deeper insight about fundamental understanding of surge response in transformer windings – with special emphasis on its standing wave phenomenon. Following this, in the latter part, elegant procedures are stitched together to determine a few electrical parameters of the transformer winding equivalent circuit that have the potential to help in assessing mechanical status of windings. Objectives of the thesis are -
1. Formulate an analytical method to determine the exact shape of standing waves for all modes in a uniform single layer coil as a solution of its governing partial differential equation
2. Estimate series capacitance of a uniform transformer winding from its measured driving point impedance
3. Determine effective air-core inductance of an iron-core uniform winding as a function of its axial length from measured driving point impedance
First part of the thesis revisits a century-old classical theory of standing waves on uniform single layer coils. Accurate information about natural frequencies and shapes of the corresponding standing waves are essential for gaining a deeper understanding of the response of coils to impulse excitations. Analytical studies on coils have largely been based on the assumption that standing waves are sinusoids in both space and time. However, this contradicts the results from numerical circuit analysis and practical measurements. So, this thesis attempts to bridge this discrepancy by revisiting the classical standing wave phenomena in coils. It not only assesses the reason for the aforementioned inconsistency, but also makes a contribution by analytically deriving the exact mode shape of standing waves for both neutral open/short conditions. For this, the coil is modelled as a distributed network of elemental inductances and capacitances, while an exponential function describes the spatial variation of mutual inductance between turns. Initially, an elegant derivation of the governing partial differential equation (in terms of voltage as the variable instead of flux) for surge distribution is presented and to the best of our knowledge, for the first time, an analytical solution for the same has been found by the variable-separable method to find the complete solution (sum of time and spatial terms). Hyperbolic terms in the spatial part of the solution have always been neglected but are included here, thus, yielding the exact mode shapes. For verification, both voltage and current standing waves computed from the analytical solution were plotted and compared with PSPICE simulation results on a 100-section ladder network representing a uniform single-layer coil. Then, practical measurements were made on a tailor-made large-sized single layer coil with a length of 2.02 m, diameter of ~1 m and having 640 turns. It turns out that even in such simple single layer coils, the shape of standing waves of all modes deviates considerably from being sinusoidal. It was further observed that this deviation depends on spatial variation of mutual inductance, capacitive coupling, and order of the standing waves.
In the second part, an elegant method for determining the series capacitance (Cs) and air-core equivalent inductance of a uniform winding as a function of its axial length (termed as M0x in this thesis) of a uniform transformer winding, from its measured DPI magnitude, is discussed. Knowledge about the series capacitance of the winding is essential, which along with shunt capacitance, determines the initial impulse voltage distribution when a surge impinges on the winding. Unlike previously published approaches, the proposed method does not involve any cumbersome and time-consuming curve-fitting or running of optimization/search algorithms. Neither does it require winding geometry data. The proposed procedure for finding series capacitance relies on a property that is observable in the driving point impedance (DPI) function of a lossless winding with an open neutral condition, viz., the ratio of the product of squares of open circuit natural frequencies to the product of squares of short circuit natural frequencies bears a particular relation to the coefficients of the DPI function. A simple procedure involving a deft manipulation and combination of a few well-known properties that correlate the roots of a polynomial to its coefficients are then utilized for determining series capacitance.
Knowledge about equivalent air-core inductance distribution as a function of its axial length (i.e., M0x) is useful for localizing a minor/incipient mechanical fault in the winding. A physically realizable empirical relationship to estimate M0x is initially proposed. The corresponding constants of the empirical relationship are then calculated from the measured DPI. The proposed method requires three DPI measurements: one with neutral-end open and the other with neutral-end shorted. The third DPI is measured with a known external lumped capacitance connected between the neutral and ground. This method requires only the first few dominant natural frequencies observable in the first two of the DPIs.
Feasibility of proposed methods for estimating Cs and M0x was initially verified by simulation on an N-section ladder network and then by experiments on small-sized continuous-disk and interleaved-disk windings, and finally on a large-sized 33 kV, 3.5 MVA continuous-disk winding. Salient features of the proposed methods are – they are simple, elegant and involve minimum post-processing after measuring the DPI. Given its inherent simplicity and their relevance, the author is hopeful that industry will come forward to implement these procedures on an existing FRA measuring instruments – thus opening a new dimension to FRA measurements
Python Indian Weather Radar Toolkit (pyiwr): An Open-Source Python Library for Analyzing & Visualizing Weather Radar Data
No full text<p>pyiwr is an advanced open-source library developed by researchers at the SIGMA Research Lab at IIT Indore. This powerful tool is designed to effortlessly convert raw ISRO Doppler Weather Radar (DWR) data files and Restructure open source dual-pol radar NetCDF files into Py-ART compatible NetCDF files. pyiwr also provides a range of useful tools and visualization functions to facilitate working with and analyzing weather radar data. It uses Pyart to create radar objects and gridded data, so please remember to cite <strong>Py-ART</strong> as well.</p>
<p><strong>Installing from source:</strong></p>
<p>Installing pyiwr from source is the only way to get the latest updates and enhancement to the software that have not yet made it into a release. The latest source code for pyiwr can be obtained from the GitHub repository, <a href="https://github.com/syedhamidali/PyScanCf.git">https://github.com/nitigsingh/pyiwr.git</a>. For further information about how to use pyiwr, please consult the documentation available at <a href="https://nitigsingh.github.io/pyiwr">https://nitigsingh.github.io/pyiwr</a>.</p>
<p><strong>To install pyiwr, follow these steps:</strong></p>
<ul>
<li>Create a new Conda environment (named <code>pyiwr</code> in this example) with the required dependencies:</li>
</ul>
<pre><code>conda create -n pyiwr python=3.9 jupyter git -c conda-forge</code>
</pre>
<ul>
<li>Activate the newly created Conda environment:</li>
</ul>
<pre><code>conda activate pyiwr</code>
</pre>
<ul>
<li>Install pyiwr using pip:</li>
</ul>
<pre><code>pip install git+https://github.com/nitigsingh/pyiwr.git</code>
</pre>
<p><strong>Citation:</strong></p>
<p>Singh Nitig, Tyagi Vaibhav, Das Saurabh, Sahoo Udaya Kumar, Kundu Shyam Sundar. (2023). Python Indian Weather Radar Toolkit (pyiwr): An Open-Source Python Library for Analyzing & Visualizing Weather Radar Data. Zenodo. <a href="https://doi.org/10.5281/zenodo.8192061">https://doi.org/10.5281/zenodo.8192061</a></p>Developers
1. Nitig Singh, MS Research, SIGMA Research Lab, IIT Indore
2. Vaibhav Tyagi, Ph.D. Research Scholar, SIGMA Research Lab, IIT Indor
A clinical study of early manifestations of dengue fever and outcome in children
Get PDFBackground: In the past few decades the incidence,
distribution, and clinical severity of Dengue have increased
dramatically. Population growth in the tropics provides many
susceptible hosts. Uncontrolled urbanization leads to
inadequate management of water and waste, providing a range
of large water stores and disposable, non-biodegradable
containers that become habitats for the larvae. Children are
now being increasingly affected by this disease. We in this
present study tried to study clinical, hematological, and hepatic
dysfunction in the early course of the disease.
Methods: The present prospective observational study was
conducted at Prathima Institute of Medical Sciences, Nagnur,
Karimnagar. N=75 children between the age group of 6 months
to 15 yrs presenting with symptoms and signs suggestive of
dengue fever as per WHO criteria were included in the study.
Complete history and clinical examination were done.
Investigations were performed as per the proforma.
Results: From n=75 children n=56 (75%) belongs to dengue
with warning signs and severe dengue whereas n=19 cases
(25%) belong to mild dengue group. the symptoms recorded
out of n=75 (100%) children presented with fever as the
predominant complaint followed by vomiting (49%), Retroorbital pain (28%), Abdominal pain (26%), Edema (25%),
Bleeding (19%) and rashes (12%), body ache (8%). The range
of platelet count at admission was 4,000 – 98,000/cmm, with
a mean value of 53,000 (P>0.05). The WHO criteria of a low
platelet count of < 100,000/cmm were seen in all cases (100%).
Conclusion: in children, importance should be given to
symptoms like fever, vomiting, bleeding, musculoskeletal pain,
flushing, and abdominal pain. If these are associated with
hepatomegaly, positive tourniquet test, low platelet count, and
elevated liver enzymes, a strong possibility of dengue to be
considered, especially during an epidemic. During the
epidemic, dengue should be considered on the differential
diagnosis of any child presenting with fever
A study of clinical, bacteriological and radiological profile of severe pneumonia in children
Get PDFPneumonia continues to pose a threat to health of children in
developed and developing countries despite improvements in
socioeconomic status, immunization and early diagnosis and
treatment. Universality, vulnerability and frequency of
occurrence of ALRTI in children are well recognized all over
the world.
Methods: This prospective clinical study of severe pneumonia
conducted on n=150 children who were admitted to pediatric
wards and PICU in PIMS, Nagunoor, Karimnagar. A detailed
examination of each child including anthropometry was carried
out. During the general physical examination, emphasis was
laid on assessing general condition of the child, respiratory
rate (counted over 1 minute), presence of fever and other signs
such as cyanosis and pallor. Detailed systematic examination
of the respiratory, cardiovascular and central nervous system
was done. Any associated illness such as septicemia, meningitis
and congestive cardiac failure if present was noted.
Result: In this prospective study, n=150 cases of severe
pneumonia were studied. In the present study, majority of
cases (53%) were less than one year of age. majority of the
cases were diagnosed as Bronchopneumonia (66.67%), Lobar
pneumonia was diagnosed in 18.6% of cases and pneumonia
and its complications in 9.3% of cases. In the present study,
radiological findings were present in 80.66% of cases Bacterial
pneumonia was detected in 62.67%, viral pneumonia in 14%.
Culture was positive in only of cases. S. pneumonia was the
most common organism isolated (6 cases) followed by S. aureus
(n=5 cases) and Klebsiella (n=3 case). n the present study,
antibiotics were given in all cases.
Conclusion : In this study we found Bronchopneumonia is the
predominant form of presentation in infants and preschool
children. Among the risk factors studied, previous history of
similar illness, inappropriate immunization for age, anemia,
PEM grade 3 and 4, were found significant causes for severe
pneumoni
Serum Procalcitonin and C Reactive Protein in as early markers neonatal sepsis- A prospective study
Get PDFNeonatal sepsis is one of the commonest causes of morbidity
and mortality in neonates in India compared to the developed
countries. Aim: To evaluate the Procalcitonin level this is an
early marker in the diagnosis of neonatal sepsis and to assess
the suitability of this test in the diagnosis of early-onset sepsis.
Method: The prospective study was conducted in the Neonatal
Division of Department of Pediatrics, Prathima Institute of
Medical Sciences over a period of one year. The blood samples
from 100 babies meeting the inclusion and exclusion criteria
constituted the material for study.
Result: Among the n=100 cases n=39 were procalcitonin
positive, compared with gestational age 10 (43.5%) cases were
positive with a gestation of <37 weeks and 24 (31.2%) cases
positive of cases >37 weeks and there was no statistical
significance concerning gestational age the association of
material characteristics with procalcitonin positive and CRP
positive levels. Blood culture was positive in n=9 (9%) of babies
with (90% CI, 5.3-14.9) and negative in n=91 (91%) of babies
with (90% CI, 85.2-94.7).
Conclusion: A positive blood culture is the only definitive and
gold standard for confirming a case of sepsis. Since the culture
and sensitivity test requires a minimum period of 48 hours
which is a precious time in deciding on the treatment of sepsis
in the newborn. Rapid diagnosis by using Procalcitonin and
CRP gives a reasonable degree of accuracy in diagnosing
neonatal sepsis and will also guide antibiotic therapy.
Procalcitonin in comparison with CRP has better sensitivity and
hence can detect most cases of neonatal sepsis and better
negative predictive value
All-Pairs Shortest-Paths Problem for Unweighted Graphs in O(n2 log n) Time
No full textGiven a simple connected unweighted undirected graph G = (V (G), E(G)) with |V (G)| = n and |E(G)| = m, we present a new algorithm for the all-pairs shortest-path (APSP) problem. The running time of our algorithm is in O(n2 log n). This bound is an improvement over previous best known O(n2.376) time bound of Raimund Seidel (1995) for general graphs. The algorithm presented does not rely on fast matrix multiplication. Our algorithm with slight modifications, enables us to compute the APSP problem for unweighted directed graph in time O(n2 log n), improving a previous best known O(n2.575) time bound of Uri Zwick (2002)
N-Hydroxypyridine-2-thione carbamates. VII. Intermolecular addition and addition-cyclization reactions of aminium cation radicals
No full textAnalysis of functional domains of Par-4
No full textPar-4 is a tumor suppressor protein with pro-apoptotic function. Sequence analysis and secondary structure predictions indicated the presence of coiled coil domain with leucine heptad repeat and a SAC domain with a NLS which is of pharmaceutical interest because it induces apoptosis selectively in cancer cells but not in normal cells. Previously it was shown to be an intrinsically disordered protein. Apparently the full length Par-4 does not fold properly and is subsequently prone to aggregation. Therefore the protein was divided into two functional domains which were investigated separately. The CC domain was purified and crystallized to obtain diffracting crystals. For the determination of experimental phases SeMet labeled CC domain was crystallized. MAD data sets were useful to 2.9 Å. The space group determination was complicated by the presence of merohedral twinning. Also non-merohedral twinning of isomorphous subgroups was investigated. Consequently models were built in three space groups and refined. From the results of the refinements it was concluded based on the free R-value of 34 % that the proper space group is P4. All models showed the presence of parallel running dimeric canonical coiled coil domains with a leucine zipper sub-domain. SAC domain purification was cloned and purified. CD experiments showed the presence of residual structure with predominant random coil profile. Among the prepared phosphorylation mimicking mutants, SAC-T155E was found to have different properties than the native protein. It was shown to be shifted towards the pre-molten globular state by CD spectroscopy. 2D H-N HSQC NMR experiments also showed shifts for some peaks which reflects the change in the surrounding environment of the amino acid residues, proving a weak but consistent change. First crystallization experiments of SAC domain with a Bcl-2 DNA fragment were performed. The observed dimerization behavior of the CC domain and the SAC domain can explain apparently contradicting results reported from in vivo experiments: in the light of these experiments the functional apoptosis inducing unit appears to be the SAC domain dimer which requires the CC domain for dimerization
IONIC LIQUID CATALYSIS TO PRODUCE COTTONSEED OIL BY TRANSESTERIFICATION AND PERFORMANCE TEST IN DIESEL ENGINE
No full textThis work is based on the performance of biodiesel blends with diesel in providing for a suitable alternative fuel. There are various methods in which the biodiesel blends are made. Every approach uses the preparation of biofuel initially from a parent oil blend. Here cottonseed oil is taken to make biodiesel. For the conversion ionic liquids have been used as catalysts. The process of transesterification has shorter reaction times with ionic liquid usage. Then subsequently test is made on a diesel engine particularly suited for alternative fuels to find out the biodiesel performance. All the tests to find the suitability of the transesterified biofuel for use in a diesel engine have been done and results presented. The performance graphs show B30 to be the optimum based biofuel blend for which maximum efficiency has been found
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