200 research outputs found
Effects of Internal Resistance on Performance of Batteries for Electric Vehicles
No full textABSTRACT Effects of Internal Resistance on Performance of Batteries for Electric Vehicles by Rohit A Ugle The University of Wisconsin-Milwaukee, 2013 Under the Supervision of Professor Anoop K. Dhingra An ever increasing acceptance of electric vehicles as passenger cars relies on better operation and control of large battery packs. The individual cells in large battery packs do not have identical characteristics and may degrade differently due to their manufacturing variability and other factors. It is beneficial to evaluate the performance gain by replacing certain battery modules/cells during actual driving. The following are the objectives of our research. We will develop an on-line battery module degradation diagnostic scheme using the intrinsic signals of a battery pack equalization circuit. Therefore, a battery "health map" can be constructed and updated in real time. Next based on the derived battery health map, the performance of the battery pack will be evaluated a user specified trip so as to evaluate the "worthiness of replacing" certain modules/cells. Different electric vehicles have different performance for the same driving cycle. These variations are due to variation in driving patterns, traffic, different light patterns, random behavior of the drivers etc. To account for this random behavior of the electric vehicle performance we generate 100 random trip cycles. We aim to model the behavior of the driving cycle and battery behavior. Finally, the thesis also explores the possibility of energy exchange between the battery packs and the smart grid. In the smart grid scenario where we have the knowledge of the electricity price and the load patterns on the grid, it is beneficial for the user to schedule charging and discharging patterns for electric vehicles. Our research will define charging and discharging patterns throughout the life of the battery. We will optimize the charging and discharging times and define the opportunity cost for each day during summer and winter months. The objective is to maximize the profit earned by selling excess energy in the battery to the grid and minimize the charging cost for the electric vehicle
Who Changed Delhi's Air? The Roles of the Court and the Executive in Environmental Decisionmaking
Get PDFAlthough there is general public approval of the improvements in Delhi’s air quality in the recent years, the process by which this change was brought about has been criticized. A common perception is that air quality policies were prescribed by the Supreme Court, and not by an institution with the mandate for making environmental policy. A careful review of the policy process in Delhi suggests otherwise. We find that the government was intimately involved in policymaking and that the main role of the Supreme Court was to force the government to implement previously announced policies. A good understanding of what happened is essential, as the Delhi experience for instituting change has become a model for other Indian cities as well as neighboring countries.air quality, Supreme Court, compressed natural gas, Delhi
Influence of the glide path on various parameters of root canal prepared with WaveOne reciprocating file using cone beam computed tomography
No full textBackground: Nickel-titanium (NiTi) rotary instrumentation carries a risk of fracture, mainly as a result of flexural (fatigue fracture) and torsional (shear failure) stresses. This risk might be reduced by creating a glide path before NiTi rotary instrumentation. The aim of this study was to compare various root canal parameters with the new WaveOne single-file reciprocating system in mesial canals of mandibular molars with and without glide path using cone beam computed tomography (CBCT).
Materials and Methods: One hundred mandibular molar teeth with canal curvature between 20° and 30° were divided into two groups of 50 teeth each. In Group 1, no glide path was created, whereas in Group 2, a glide path was created with PathFiles at working length (WL). In both groups, canals were shaped with WaveOne primary reciprocating files to the WL. Canals were scanned in a CBCT unit before and after instrumentation. Postinstrumentation changes in canal curvature, cross-sectional area, centric ability, residual dentin thickness, and the extent of canal transportation were calculated using image analysis software and subjected to statistical analysis. Data were analyzed using Student′s t-test and Mann-Whitney U-test (P < 0.05).
Results: The mean difference of root canal curvature, cross-sectional area, centric ability, and residual dentin thickness increased, whereas it reduced significantly for canal transportation in Group 2.
Conclusion: WaveOne NiTi files appeared to maintain the original canal anatomy and the presence of a glide path further improves their performance and was found to be beneficial for all the parameters tested in this study
Self-assembled strained nanostructures for light emission grown using molecular beam epitaxy
Get PDFIII-V nanostructures are widely researched for applications in dislocation-resistant light emitters for photonic integrated circuits, quantum computing and single photon emitters. The 0D nanostructures include quantum dots (QDs), dot in a well (DWELLs), sub-monolayer QDs and droplet epitaxy QDs, while 1D elongated structures include quantum dashes and nanowires (NWs). The optical properties of nanostructures can be controlled through size, composition, strain and band-offsets during epitaxial growth and can be tailored precisely to emit light with photon energies suited to the application, spanning 0.2-2.0 eV. This thesis explores two novel QD based light emitters in the visible and near-infrared wavelength regime. In the first part of the thesis, we demonstrate the growth and characterization of tensile strained Ge QDs and Ge NWs phase segregated in the III-V matrix via Volmer-Weber growth mode emitting at 1200 nm. The second part of the thesis demonstrates the dislocation tolerance of compressively strained InP QDs grown on lattice-matched GaAs and lattice-mismatched Si substrate via Stranski-Krastanov growth mode emitting at 713 nm.
The first part of the thesis explores the growth of tensile strained Ge QDs and NWs phase segregated in the III-V matrix. Epitaxial growth of phase segregated Ge nanostructures embedded within III-V compound semiconductors is a promising way to achieve a high biaxial tensile strain along with precise control of nanostructure density, size and morphology. Here we demonstrate growth of phase-segregated Ge quantum dots (QDs) and compare them to our previously reported Ge nanowires (NWs); both are strained to an In0.52Al0.48As matrix with a high biaxial tensile strain of 3.6%. Despite the similar growth conditions, there exist pronounced differences in the lateral size and planar density of Ge QDs and Ge NWs, with Ge QDs showing significantly larger size, lower density and structural anisotropy along the in-plane [1-10] direction. In addition to the difference in morphology, Ge QDs are shown to be more prone to plastic relaxation by formation of dislocations and stacking faults, which we attribute to their larger in-plane size. Finally, tensile Ge QDs are shown to exhibit strong room-temperature photoluminescence at 1176 nm, which is blueshifted from the case of Ge NWs.
In the second part of the thesis, we demonstrate epitaxial InP QDs on GaAs on Si virtual substrates with room-temperature photoluminescence (PL) intensity nearly identical to those grown on GaAs substrates. The similarity in PL characteristics is remarkable considering that the active region on the GaAs/Si virtual substrate has a threading dislocation density (TDD) of ~3×10^7 cm-2, as compared to the bulk GaAs substrate with TDD 50× improvement in the luminescence intensity of InP QDs annealed at ~700⁰C for 100 minutes without observable structural degradation or blue-shift in the PL spectrum.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-05-01The student, Pankul Dhingra, accepted the attached license on 2019-04-25 at 12:06.The student, Pankul Dhingra, submitted this Thesis for approval on 2019-04-25 at 12:16.This Thesis was approved for publication on 2019-04-25 at 14:10.DSpace SAF Submission Ingestion Package generated from Vireo submission #13914 on 2019-08-22 at 16:23:56Made available in DSpace on 2019-08-23T20:48:26Z (GMT). No. of bitstreams: 2
DHINGRA-THESIS-2019.pdf: 2735717 bytes, checksum: 55584f4a818d3f00a92b3ad38753e24d (MD5)
LICENSE.txt: 4211 bytes, checksum: 108fd1426b2a5d615ea1ebad7d58e69f (MD5)
Previous issue date: 2019-04-25Embargo set by: Seth Robbins for item 112387
Lift date: 2021-08-23T20:48:32Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 112387 on 2021-08-24T09:15:38Z
Rotavirus Diarrhea and its Determinants Among Under-Five Children Admitted in a Tertiary Care Hospital of Southern Haryana, India
No full textThis is the accepted manuscript version of the work published in its final form as Goel, A.K., Chawla, S., Dhingra, A. et al. Rotavirus Diarrhea and its Determinants Among Under-Five Children Admitted in a Tertiary Care Hospital of Southern Haryana, India. Indian J Pediatr 88, 16–21 (2021). https://doi.org/10.1007/s12098-020-03616-1.
Deposited by shareyourpaper.org and openaccessbutton.org. We've taken reasonable steps to ensure this content doesn't violate copyright. However, if you think it does you can request a takedown by emailing [email protected]
Performance Optimization of Onboard Lithium Ion Batteries for Electric Vehicles
No full textNext generation of transportation in the form of electric vehicles relies on better operation and control of large battery packs. The individual modules in large battery packs generally do not have identical characteristics and may degrade differently due to manufacturing variability and other factors. Degraded battery modules waste more power, affecting the performance and economy for the whole battery pack. Also, such impact varies with different trip patterns. It will be cost effective if we evaluate the performance of the battery modules prior to replacing the complete battery pack. The knowledge of the driving cycle and battery internal resistance will help to make decision to replace the worst battery modules and directly cut down on user expenditure to replace the battery. Also, optimizing the performance of battery during the driving trip is the challenging task to achieve. The knowledge of energy prices of the grid, internal resistance of the lithium ion battery pack on the electric vehicle, the age of the battery and distance travelled by the electric vehicle are very important factors on which the cost of daily driving cycle is dependent. In near future, the energy consumed by the electric vehicles will create a major consumer market for the smart grids. The smart grid system is complemented by the renewable energy sources that contribute and support the grid. The electric vehicles are not only predicted as energy consumers but also as dynamic sources of energy. These vehicles can now travel more than 100 miles with a single charging cycle whereas average day to day commute is well below the maximum capacity of these vehicles. This leaves the driver with the extra energy on the battery pack which can be used later for supporting energy requirement from the grid. As we know that cells/modules in large battery packs do not have identical properties and these degrade at different rates during the course of their lifespan. It is beneficial for the user to quantify the amount of energy that can be used to support the grid. The improvement of the electric grid to the next generation infrastructure ie ‘Smart Grid’ will enable diverse opportunities to contribute the energy and balance the load on the grid. The information about the grid like price quality, load etc will be available to the people very easily. This information can be useful to make the energy grid more economical and environment friendly. We have used the information for price of energy on the grid to optimize the cost of daily driving cycle. The goal of this research is to accurately predict the battery behavior for the daily driving cycle. The prediction of battery behavior will help the driver to decide the optimum charging patterns, energy consumed during driving and the surplus energy available in the batteries. The prior knowledge of the battery behavior, price of the energy on the grid and the trip travel will help the driver to minimize the cost of travel on daily basis as well as throughout the life of the battery
Accelerating (Compressed) SENSE Scans in MRI
No full textMagnetic Resonance Imaging is a painless procedure to produce high-resolution diagnostic images. Today, it is one of the essential clinical imaging modalities. One of the major challenges involved with this imaging modality is its long scanning time. Parallel imaging in combination with compressed sensing has overcome this challenge to a great extent. As a quid pro quo for this reduced scan time is the increase in image reconstruction time. An extensive research is focused to develop algorithms to make the image reconstruction faster. Fast Iterative Shrinkage Threshold algorithm is one of these algorithms (which is clinically viable) that speeds up the image reconstruction process. The present project focuses to speed up the particular algorithm, fast iterative shrinkage threshold algorithm, by preconditioning the convex optimization problem. This work proposes two new preconditioners, specifically in the context of the given algorithm, but otherwise can be used with different frameworks solving similar problems. The first preconditioner is a degree one polynomial of the system matrix and the second preconditioner is a block diagonal matrix where each block is a circulant matrix. The preconditioners are evaluated using two stopping criteria: residual error and relative error. The computation complexity of both the preconditioners are evaluated by measuring the floating point operations and total time consumption. Additionally, the simulations are performed by undersampling the data at two factors r=2 and r=4. The results indicate that the polynomial preconditioner reduces the overall time by a factor of 0.25 however is computationally expensive to construct. On the other side, block diagonal circulant preconditioner is extremely cheap to construct and evaluate on a vector but does not provide the desired results within the current framework. The study concludes that a suitable preconditioner for FISTA is the one that without affecting the largest eigenvalue of the system matrix improves the condition number and simultaneously is cheap to construct and evaluate.Electrical Engineerin
Understanding Non-Photochemical Laser Induced Nucleation
No full textNucleation is the initial step for the creation of new crystalline phase. A precise control over nucleation and its kinetics is important for both research and industries. Thus, alternative methods are sought after to extend the toolbox for controlling nucleation. In the 1990's, Non-Photochemical Laser Induced Nucleation (NPLIN) was suggested as a promising method to alter the nucleation kinetics. Since then, several reports have demonstrated that NPLIN dramatically reduces the nucleation induction time and controls polymorphism of various fine chemicals relevant for industrial practice. Although different hypotheses have been proposed in literature to explain the experimental observations, the mechanism behind NPLIN is still unknown.The objective of this work is to extend the mechanistic understanding of NPLIN. This has been approached by qualitatively studying the effect of different factors on the nucleation efficiency of the non-photochemical process using unfocused pulsed laser in aqueous supersaturated solution of KCl. The factors investigated include wavelength, peak intensity, supersaturation, mixing, and impurity level of the solution. Each of these parameters are studied using high number of samples (80-100) to generate a robust set of results and to avoid the stochastic nature of nucleation.In a separate series of experiments, an acoustic wave was detected in the solution due to the non-linear interaction of the unfocused laser with the system by measuring the pressure signal with a piezo-electric transducer placed just below the air-liquid interface. Further experiments were executed to understand the nature of the acoustic wave and its influence on NPLIN. The results show that laser could induce nucleation at significantly low peak intensities, much below the previously reported intensity threshold in literature. It is also observed that NPLIN shows a strong dependence on peak intensity, supersaturation, impurity level, and mixing of the solution while the dependence on wavelength was found to be weak. Furthermore, the acoustic wave experiments show that the laser induced pressure fluctuations do not affect the nucleation efficiency of the process. Overall, the results suggest that several mechanisms play a role during laser induced nucleation. To summarize, the research provides a robust analysis of different factors that can influence NPLIN. The results can be further utilized to enhance the understanding and applicability of the process
- …
