FDI and Political Stability in India

Shekhar Kumar Patel(파텔 시카 쿠마) 충남대학교 사회과학연구소 2013 사회과학연구 Vol.24 No.1

Cone-beam computed tomography usage: An alert to the field of dentistry

Shekhar Bhatia,Shivani Kohli 대한영상치의학회 2016 Imaging Science in Dentistry Vol.46 No.2

A Case Study of Wear in a High Head Francis Turbine Due to Suspended Sediment and Secondary Flow in a Hydropower Plant of Nepal

Shekhar Aryal,Sailesh Chitrakar,Rajendra Shrestha,Ajay Kumar Jha 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.4

The hydropower plants under Himalayan basins are mostly characterized by heavy sediment load due to geographical and metamorphic constraints. Run-off-river projects with limited size of the desilting basins allow suspended sediments to get carried into the turbine components causing wear due to sediment erosion. In the case of high head power plants consisting of Francis turbines, a large portion of the hydraulic energy is transformed into kinetic energy within the guide vanes. This causes various instabilities in the flow due to high acceleration and velocity. Some recent studies have shown that due to the combined effect of the secondary flow around the guide vanes and sediment carrying flow, the size of the clearance gap increases, which further aggravates the performance of the turbine. This study takes a reference of one of the power plants in Nepal containing high head Francis turbines. An in-depth analysis of the effect of the sediment in this power plant and sediment erosion in the turbine components has been performed. A CFD analysis of the guide vanes and runner blades corresponding to the same turbine has been conducted and the results are used to analyze the erosion pattern on the actual turbine. The detailed erosion analysis is made possible with a 3D scanner, such that the eroded regions can be captured and classified based on the flow behavior at those regions. Guide vanes and runner blades are found to be the predominant components affected by erosion. It has been seen that most of the erosion affected regions are originated from increasing clearance gaps between guide vane and facing plates caused due to continuous leakage flow within the two sides of the guide vanes.

Extensive Analysis of Gate Leakage Current in Nano-Scale Multi-gate MOSFETs

Shekhar Yadav,Hemant Kumar,Chandra Mohan Singh Negi 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.6

Excessive gate leakage is crucial for nanoscale metal oxide semiconductor field-effect transistors (MOSFETs), resulting in unnecessary static power dissipation and switching delay. Herein, we used three-dimensional modeling to understand the gate leakage behavior of various nanoscale MOSFETs, including fin field-effect transistor and gate all around MOSFET. We used Wentzel–Kramers–Brillouin approximation to compute the direct quantum tunneling-based gate leakage current. We performed all computations of quantum transport for gate leakage current through the non-equilibrium Greens function approach. Among the MOSFET structures under study, the gate all around MOSFET demonstrates the most profound gate leakage deviation with the gate material work function and oxide thickness. A detailed analysis of the dependence of the gate leakage on the metal work function is presented, and the charge density model is used to explain this dependence. This work explores the possibilities of controlling the gate leakage through gate material variations in different nanoscale multi-gate MOSFET architectures.

Mapping nanoscale effects of localized noise-source activities on photoconductive charge transports in polymer-blend films

Shekhar, Shashank,Cho, Duckhyung,Cho, Dong-Guk,Yang, Myungjae,Hong, Seunghun IOP 2018 Nanotechnology Vol.29 No.20

<P>We develolped a method to directly image the nanoscale effects of localized noise-source activities on photoconducting charge transports in domain structures of phase-separated polymer-blend films of Poly(9,9-di-n-octylfluorenyl-2,7-diyl) and Poly(9,9-di<I>-n</I>-octylfluorene-<I>alt</I>-benzothiadiazole). For the imaging, current and noise maps of the polymer-blend were recorded using a conducting nanoprobe in contact with the surface, enabling the conductivity (<I>σ</I>) and noise-source density (<I>N</I> <SUB>T</SUB>) mappings under an external stimulus. The blend-films exhibited the phase-separation between the constituent polymers at domains level. Within a domain, high <I>σ</I> (low <I>N</I> <SUB>T</SUB>) and low <I>σ</I> (high <I>N</I> <SUB>T</SUB>) regions were observed, which could be associated with the ordered and disordered regions of a domain. In the <I>N</I> <SUB>T</SUB> maps, we observed that noise-sources strongly affected the conduction mechanism, resulting in a scaling behavior of <I>σ</I>?∝?<img ALIGN='MIDDLE' ALT='${{N}_{{\rm{T}}}}^{-0.5}$' SRC='http://ej.iop.org/images/0957-4484/29/20/205204/nanoaab2ddieqn1.gif'/> in both ordered and disordered regions. When a blend film was under an influence of an external stimulus such as a high bias or an illumination, an increase in the <I>σ</I> was observed, but that also resulted in increases in the <I>N</I> <SUB>T</SUB> as a trade-off. Interestingly, the Δ<I>σ </I>versus Δ<I>N</I> <SUB>T</SUB> plot exhibited an unusual scaling behavior of Δ<I>σ</I>?∝?<img ALIGN='MIDDLE' ALT='${\rm{\Delta }}{{N}_{{\rm{T}}}}^{0.5},$' SRC='http://ej.iop.org/images/0957-4484/29/20/205204/nanoaab2ddieqn2.gif'/> which is attributed to the de-trapping of carriers from deep traps by the external stimuli. In addition, we found that an external stimulus increased the conductivity at the interfaces without significantly increasing their <I>N</I> <SUB>T</SUB>, which can be the origin of the superior performances of polymer-blend based devices. These results provide valuable insight about the effects of noise-sources on nanoscale optoelectronic properties in polymer-blend films, which can be an important guideline for improving devices based on polymer-blend.</P>

Asia and Europe are Different? : Credit Reponse to Global Bank Deleveraging

( Shekhar Aiyar ),( Sonali Jain Chandra ) 세종대학교 경제통합연구소(구 세종대학교 국제경제연구소) 2013 Journal of Economic Integration Vol.28 No.2

During the global financial crisis, European banks sharply contracted foreign claims on recipient economies. This paper examines the impact of that deleveraging on credit supply in recipient economies, with a particular focus on Asia. Identification is achieved by exploiting heterogeneity in the ex-ante patterns of funding reliance on different European banking systems, and in variation in the ratio of local claims in local currency to total foreign claims in recipient economies. These sources of variation are used to create instruments for the deleveraging shock. We find that the contraction of foreign claims in European bank was associated with a substantial reduction in domestic credit supply in a broad sample of countries. However, the credit supply response in Asia was only about half the size of the response in non-Asian countries, possibly due to stronger policy response and healthier local bank balance sheets in the Asian countries at the outset of the crisis.

Studies on thermal and swelling properties of Poly (NIPAM-co-2-HEA) based hydrogels

Shekhar, Suman,Mukherjee, M.,Sen, Akhil Kumar Techno-Press 2012 Advances in materials research Vol.1 No.4

Thermoresponsive hydrogels based on N-Isopropylacrylamide (NIPAM) and 2-Hydroxyethylacrylate (HEA) were prepared by free radical polymerization. The hydrogels were characterized by elemental (CHN) analysis, differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). DSC thermogram showed two endothermic transitions which are due to hydration of water present in different environments. One near $0^{\circ}C$ called melting transition of ice and was used to calculate the quantitative determination of the amounts of freezing and non freezing water. The other transition above the ambient temperature was due to the combination of hydrophobic hydration and hydrophilic hydration which changes with the copolymer compositions. Swelling and deswelling studies of the hydrogels were carried out using the aqueous media, salt and urea solutions. The experimental results from swelling studies revealed that copolymers have lower rates of swelling and deswelling than the homopolymer.

Hyperbolic metamaterials: fundamentals and applications

Shekhar Prashant,Atkinson Jonathan,Jacob Zubin 나노기술연구협의회 2014 Nano Convergence Vol.1 No.14

Metamaterials are nano-engineered media with designed properties beyond those available in nature with applications in all aspects of materials science. In particular, metamaterials have shown promise for next generation optical materials with electromagnetic responses that cannot be obtained from conventional media. We review the fundamental properties of metamaterials with hyperbolic dispersion and present the various applications where such media offer potential for transformative impact. These artificial materials support unique bulk electromagnetic states which can tailor light-matter interaction at the nanoscale. We present a unified view of practical approaches to achieve hyperbolic dispersion using thin film and nanowire structures. We also review current research in the field of hyperbolic metamaterials such as sub-wavelength imaging and broadband photonic density of states engineering. The review introduces the concepts central to the theory of hyperbolic media as well as nanofabrication and characterization details essential to experimentalists. Finally, we outline the challenges in the area and offer a set of directions for future work.

Call Admission Control and Handoff Techniques for 3-G and Beyond Mobile Networks

Shekhar Verma,Geetam S. Tomar 사단법인 인문사회과학기술융합학회 2011 예술인문사회융합멀티미디어논문지 Vol.1 No.1

Cellular mobile communication Networks have many services and each type of Services has distinct characteristics and Quality of Service requirement. It is important issues in 3-G and beyond networks are to prepare a framework for multiple class service, which performs call admission and handoff efficiently. There have been handful existing mechanisms for improving Call Admission Control (CAC) and Handoff Techniques in mobile network but most of them have considered only single class of service or might have touched value of few classes but not beyond. In this paper we have considered 8 types of services, which are differentiated according to their: Acceptable delay in transmission, Buffering capacity, Transmission mode and Bit rate. In this approach CAC and Handoff issues are resolved by awarding calls with some Priority Number by which each call will be recognized. Another issue of collision in CAC and handoff will be resolved by priority and authority to access the channel. Performance of this frame- work for CAC and Handoff is evaluated by calculating Call Dropping probability and Call Completion probability in this paper.

Cervical Cancer Screening: Knowledge, Attitude and Practices among Nursing Staff in a Tertiary Level Teaching Institution of Rural India

Shekhar, Shashank,Sharma, Chanderdeep,Thakur, Sita,Raina, Nidhi Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.6

Background: Assessment of the nursing staff knowledge, attitude and practices about cervical cancer screening in a tertiary care teaching institute of rural India. Materials and Methods: A cross sectional, descriptive, interview-based survey was conducted with a pretested questionnaire among 262 staff nurses of a tertiary care teaching and research institute. Results: In this study 77% respondents knew that Pap smear is used for detection of cervical cancer, but less than half knew that Pap smear can detect even precancerous lesions of cervix. Only 23.4% knew human papilloma virus infection as a risk factor. Only 26.7% of the respondents were judged as having adequate knowledge based on scores allotted for questions evaluating knowledge about cervical cancer and screening. Only 17 (7%) of the staff nurses had themselves been screened by Pap smear, while 85% had never taken a Pap smear of a patient. Adequate knowledge of cervical cancer and screening, higher parity and age >30 years were significantly associated with self screening for cervical cancer. Most nurese held a view that Pap test is a doctor procedure, and nearly 90% of nurses had never referred a patient for Pap testing. Conclusions: The majority of nursing staff in rural India may have inadequate knowledge about cervical cancer screening, and their attitude and practices towards cervical cancer screening could not be termed positive.