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Gaurav Sharma

Other affiliations: Northeastern University, D. E. Shaw & Co., Hewlett-Packard  ...read more
Bio: Gaurav Sharma is an academic researcher from Shenzhen University. The author has contributed to research in topics: Medicine & Photocatalysis. The author has an hindex of 82, co-authored 1244 publications receiving 31482 citations. Previous affiliations of Gaurav Sharma include Northeastern University & D. E. Shaw & Co..


Papers
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Journal ArticleDOI
TL;DR: The UR-SolarCap system is designed for high efficiency and controllability and, importantly, supports auto-wakeup from a state of complete energy depletion, and is available for download as an archive containing design schematics, Printed Circuit Board files, firmware code, and a component list for assembly of the system.
Abstract: Energy harvesting systems that couple solar panels with supercapacitor buffers offer an attractive option for powering computational systems deployed in field settings, where power infrastructure is inaccessible. Supercapacitors offer a particularly compelling advantage over electrochemical batteries for such settings because of their ability to survive many more charge–discharge cycles. We share UR-SolarCap—a versatile open source design for such a harvesting system that targets embedded system applications requiring power in the 1–10 W range. Our system is designed for high efficiency and controllability and, importantly, supports auto-wakeup from a state of complete energy depletion. This paper summarizes our design methodology, and the rationale behind our design and configuration decisions. Results from the operation and testing of a system realized with our design demonstrate: 1) an achievable harvester efficiency of 85%; 2) the ability to maintain sustained operation over a two week period when the solar panel and buffer are sized appropriately; and 3) a robust auto-wakeup functionality that resumes system operation upon the availability of harvestable energy after a period in which the system has been forced into a dormant state because of a lack of usable energy. To facilitate the use of the system by researchers exploring embedded system applications in environments that lack a power infrastructure, our designs are available for download as an archive containing design schematics, Printed Circuit Board (PCB) files, firmware code, and a component list for assembly of the system. In addition, a limited number of pre-assembled kits are available upon request.

44 citations

Proceedings ArticleDOI
26 May 2009
TL;DR: In this paper, a series of parametric studies are performed by changing the die thickness, die pitch distance and top mold chaste compression velocity to predict the die shift during compression molding.
Abstract: The increased functionality of cellular phones and handheld devices requires system level integration. Thus there is a strong demand in cell phone maker to move to embedded micro wafer level packaging (EMWLP). But the major problem encountered is die shift during compression molding. This paper presents a novel method to predict the die shift during wafer level molding process. A series of parametric studies are performed by changing the die thickness, die pitch distance and top mold chaste compression velocity. The effect of thinning down the chip thickness affects the pressure difference and local shear rate on the chip surfaces. The rate of change of epoxy mold compound fluid pressure across the die top surfaces is not constant. The local shear rate is increasing linearly from the centre of the wafer to the outermost die. From the parametric studies, the die shift is inversely proportional to the die thickness for wafer level molding. Such a phenomenon will reduce the lithography alignment error in the next process. This paper also shows that by reducing die pitch distance of a 5 × 5 mm2, 500 µm thick chip, the die shift decreases by a factor of 12%. In addition, the top mold chaste compression velocity contributes to the die shift by as much as 28% when the velocity is reduced by 50% from 100 µm/sec to 50 µm/sec Finally it is observed from experiment result that the die shift is not constant in all directions.

43 citations

01 Sep 2013
TL;DR: In this article, the adsorption capacity of activated carbon prepared from guava fruit peel waste has been studied for congo dye removal using batch adaption experiments and the nonlinear Langmuir and Frendulich isotherm models are used to stimulate the equilibrium data.
Abstract: The adsorption capacity of activated carbon prepared from guava fruit peel waste has been studied for congo dye. The activation process is carried out under microwave radiations in the presence of KOH. The guava peel based activated carbon (GPAC) and unactivated carbon (GPUC) have been characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. The comparative adsorption behavior of GPAC, GPUC and commercially activated carbon (CAC) has been studied for the congo red dye removal using batch adsorption experiments. The non-linear Langmuir and Frendulich isotherm models are used to stimulate the equilibrium data. The equilibrium data is represented by the Langmuir isotherm model. The kinetic model shows that pseudo second order kinetics has best fit to the experimental data (R 2 >0.90). Thermodynamic studies conclude that adsorption process is spontaneous and endothermic in nature. GPAC has emerged as efficient adsorbent for congo dye as compared to GPUC and CAC. Further, desorption studies show that 35.74 % of metal ions can be recovered by desorption in first cycle and adsorbent can be reused.

43 citations

Journal ArticleDOI
TL;DR: In this article, a dual-function facile heterojunction and investigation of role of the charge transfer dynamism between individual semiconductor components for superior photocatalytic and electrochemical sensing application is reported.

43 citations

Journal ArticleDOI
TL;DR: Objective, noninvasive assessment of the deep venous system can be an excellent diagnostic aid, particularly when ventilation/perfusion scanning or pulmonary angiography is not readily available.
Abstract: The recent development of relatively noninvasive, sensitive and specific procedures has been responsible for new information in the pathophysiology and epidemiology of venous thrombosis. Primary emphasis has been placed on detection of thrombosis with the radioactive fibrinogen leg scan, Doppler ultrasonic recording and, more recently, electrical impedance plethysmography. The latter procedure is easily performed by trained technicians; it is also sensitive and specific and provides an immediate answer. In 95 percent of patients with angiographically confirmed pulmonary embolism, results of impedance plethysmography were abnormal, indicating deep vein thrombosis and thus establishing the relation between the site of thrombus formation and pulmonary embolism. In 90 percent of patients suspected of having pulmonary embolism, when the plethysmogram indicated deep vein thrombosis, pulmonary anglograms revealed pulmonary embolism; similarly, when the plethysmogram was normal, pulmonary angiograms revealed normal findings in 90 percent of the patients. Hence, objective, noninvasive assessment of the deep venous system can be an excellent diagnostic aid, particularly when ventilation/perfusion scanning or pulmonary angiography is not readily available. The most widely studied measure to prevent venous thrombosis has been treatment with subcutaneous small dose heparin. Although extremely effective in patients undergoing elective general surgery, this treatment has not been as effective or as appropriate in high risk patients, such as those undergoing hip, urologie or neurosurgical procedures, or in patients with malignancy. Among medically treated patients, it has been quite effective in those with acute myocardial infarction. Dextran has not been very effective in patients undergoing general surgery, although its use with relatively large volumes has resulted in favorable results in patients having hip surgery. Platelet antiaggregating agents have generally been disappointing prophylactic agents. The most recent and promising technique is intermittent pneumatic boot compression of the calves, which does not require medications that may alter blood coagulation. The results of this procedure have been impressive in general surgical, neurosurgical and urologie patients, conflicting in patients with hip surgery and poor in patients with malignancy undergoing surgery. In these groups of high risk patients, further investigations with new agents or methods or combined techniques are indicated.

42 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

01 Jun 2012
TL;DR: SPAdes as mentioned in this paper is a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler and on popular assemblers Velvet and SoapDeNovo (for multicell data).
Abstract: The lion's share of bacteria in various environments cannot be cloned in the laboratory and thus cannot be sequenced using existing technologies. A major goal of single-cell genomics is to complement gene-centric metagenomic data with whole-genome assemblies of uncultivated organisms. Assembly of single-cell data is challenging because of highly non-uniform read coverage as well as elevated levels of sequencing errors and chimeric reads. We describe SPAdes, a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler (specialized for single-cell data) and on popular assemblers Velvet and SoapDeNovo (for multicell data). SPAdes generates single-cell assemblies, providing information about genomes of uncultivatable bacteria that vastly exceeds what may be obtained via traditional metagenomics studies. SPAdes is available online ( http://bioinf.spbau.ru/spades ). It is distributed as open source software.

10,124 citations

Journal ArticleDOI

7,335 citations

Journal ArticleDOI

6,278 citations