Investigation of electron beam parameters in laser wakefield acceleration using skewed laser pulse and external magnetic field

Gopal K.,Gupta D.N.,Jain A.,Hur M.S.,Suk H. 한국물리학회 2021 Current Applied Physics Vol.25 No.-

We investigate the parameters of accelerated electron bunch in laser wakefield acceleration (LWFA), when a skewed laser pulse propagates through a plasma in the presence of a transverse magnetic field. Two dimensional particle-in-cell (2D-PIC) simulations have been performed under the consideration of pulse skewness parameter (sα = τl/τt) that is defined as the ratio of leading (τl) to trailing pulse edge (τt) duration. The injected charge is estimated as 23 pC for the laser strength parameter a0 = 2 when sα changes from 1 to 0.45 at a laser propagation distance of 1.5 mm with 50T magnetic field. The electron beam emittance reduces about 50% when leading edge of the pulse becomes two-fold sharper (sα = 0.45) with 50T magnetic field. Energy spread of accelerated electron bunch is also reduced from 18 to 6.6%. Hence, in the presence of a transverse magnetic field, the laser pulse skewness can significantly improve the quality of the accelerated electron bunch (i.e. charge, mean energy and emittance) in laser wakefield acceleration.

Reduction of noxious Cr(VI) ion to Cr(III) ion in aqueous solutions using H2O2 and UV/H2O2 systems

M.H. Dehghani,B. Heibati,A. Asadi,I. Tyagi,S. Agarwal,V.K. Gupta 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.33 No.-

Conversion of the toxic Cr(VI) to the less toxic Cr(III) in aqueous solutions by chemical andphotochemical reduction was carried out using H2O2 and UV radiation. The whole mechanism was wellelucidated and investigated using potassium dichromate (K2Cr2O7) as a standard model compound. Theeffects of potential factors affecting the reduction efficiency were well studied and optimized, theoptimized parameters such as concentration of H2O2 (from 0.5 to 1.5 M), pH (from 5 to 9), irradiationtime (0 to 140 min) and reaction time (0 to 120 min). Initial concentration of Cr(VI) in the solution wasvaried from 0.1 to 15 mg/L plays a significant role in the mechanism involves for the reduction of noxiousCr(VI) to less toxic Cr(III).

Anti-Allergic Effects of Herbal Product from Allium cepa (Bulb)

P. Kaiser,M.S. Youssouf,S.A. Tasduq,S. Singh,S.C. Sharma,G.D. Singh,V.K. Gupta,B.D. Gupta,R.K. Johri 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.2

Allium cepa (Family Liliaceae) is a reputed Indian medicinal herb that is prescribed as an effective remedy for several ailments in the Ayurvedic system of medicine. The aim of this study was to evaluate its efficacy against various events responsible for Type I allergic reactions. A herbal fraction (ALC-02) from A. cepa (bulb) inhibited histamine release and attenuated intracellular calcium levels in Compound 48/80-induced rat peritoneal mast cells. It also prevented Compound 48/80-mediated systemic anaphylaxis while lowering histamine levels in plasma. ALC-02 suppressed carrageenan-induced rat paw edema. It inhibited eosinophil peroxidase activity and protein content in bronchoalveolar lavage fluid (BALF) of ovalbumin-challenged mice. In this experiment ALC-02 also caused a substantial reduction in lipid peroxidation in BALF/lung tissue and augmented superoxide dismutase activity in lung tissue. ALC-02 suppressed erythrocytic lysis caused by Triton X-100. A significant quenching of 1,1-diphenyl-2-picrylhydrazyl radical by ALC-02 was observed. The results have shown a promising anti-allergic profile of ALC-02 that could be attributed to its potential antihistaminic, anti-inflammatory, and antioxidant activities.

Anti-Allergic Effects of Herbal Product from Allium cepa (Bulb)

Kaiser, P.,Youssouf, M.S.,Tasduq, S.A.,Singh, S.,Sharma, S.C.,Singh, G.D.,Gupta, V.K.,Gupta, B.D.,Johri, R.K. The Korean Society of Food Science and Nutrition 2009 Journal of medicinal food Vol.12 No.2

Allium cepa (Family Liliaceae) is a reputed Indian medicinal herb that is prescribed as an effective remedy for several ailments in the Ayurvedic system of medicine. The aim of this study was to evaluate its efficacy against various events responsible for Type I allergic reactions. A herbal fraction (ALC-02) from A. cepa (bulb) inhibited histamine release and attenuated intracellular calcium levels in Compound 48/80-induced rat peritoneal mast cells. It also prevented Compound 48/80-mediated systemic anaphylaxis while lowering histamine levels in plasma. ALC-02 suppressed carrageenan-induced rat paw edema. It inhibited eosinophil peroxidase activity and protein content in broncho alveolar lavage fluid (BALF) of ovalbumin-challenged mice. In this experiment ALC-02 also caused a substantial reduction in lipid peroxidation in BALF/lung tissue and augmented superoxide dismutase activity in lung tissue. ALC-02 suppressed erythrocytic lysis caused by Triton X-100. A significant quenching of 1,1-diphenyl-2-picrylhydrazyl radical by ALC-02 was observed. The results have shown a promising anti-allergic profile of ALC-02 that could be attributed to its potential antihistaminic, anti-inflammatory, and antioxidant activities.

High-Field Solenoid Development for Axion Dark Matter Search at CAPP/IBS

Gupta, R.,Anerella, M.,Ghosh, A.,Sampson, W.,Schmalzle, J.,Konikowska, D.,Semertzidis, Y. K.,Shin, Y. Institute of Electrical and Electronics Engineers 2016 IEEE transactions on applied superconductivity Vol.26 No.4

<P>Construction and test results of a 100-mm-bore solenoid made with the high-temperature superconductor (HTS) producing a peak field of over 10 T are presented. This is the first step toward building a very high field solenoid (35-40 T) one of the key components of the proposed state-of-the-art facility for dark matter search at the Center for Axion and Precision Physics Research, Institute for Basic Science in Korea. The coils made with HTS are expected to provide a field of similar to 25 T, and the coils made with low-temperature superconductors are expected to provide a field of 10-15 T. REBCO HTS tapes were provided by SuNAM along with the measurements at 20 K in 3.5- to 4-T applied field. The Brookhaven National Laboratory measured several samples at 4 K in the applied field of 4-8 T. This paper will present a series of test results of the conductor, six pancake coils, and the fully assembled solenoid.</P>

The Region of Positivity and Unimodality in the Truncated Series of a Nonparametric Kernel Density Estimator

Gupta, A.K.,Im, B.K.K. The Korean Statistical Society 1981 Journal of the Korean Statistical Society Vol.10 No.-

This paper approximates to a kernel density estimate by a truncated series of expansion involving Hermite polynomials, since this could ease the computing burden involved in the kernel-based density estimation. However, this truncated series may give a multimodal estimate when we are estiamting unimodal density. In this paper we will show a way to insure the truncated series to be positive and unimodal so that the approximation to a kernel density estimator would be maeningful.

An Improved Approach to Ranking Web Documents

Gupta, Pooja,Singh, Sandeep K.,Yadav, Divakar,Sharma, A.K. Korea Information Processing Society 2013 Journal of information processing systems Vol.9 No.2

Ranking thousands of web documents so that they are matched in response to a user query is really a challenging task. For this purpose, search engines use different ranking mechanisms on apparently related resultant web documents to decide the order in which documents should be displayed. Existing ranking mechanisms decide on the order of a web page based on the amount and popularity of the links pointed to and emerging from it. Sometime search engines result in placing less relevant documents in the top positions in response to a user query. There is a strong need to improve the ranking strategy. In this paper, a novel ranking mechanism is being proposed to rank the web documents that consider both the HTML structure of a page and the contextual senses of keywords that are present within it and its back-links. The approach has been tested on data sets of URLs and on their back-links in relation to different topics. The experimental result shows that the overall search results, in response to user queries, are improved. The ordering of the links that have been obtained is compared with the ordering that has been done by using the page rank score. The results obtained thereafter shows that the proposed mechanism contextually puts more related web pages in the top order, as compared to the page rank score.

An Improved Approach to Ranking Web Documents

Pooja Gupta,Sandeep K. Singh,Divakar Yadav,A. K. Sharma 한국정보처리학회 2013 Journal of information processing systems Vol.9 No.2

Ranking thousands of web documents so that they are matched in response to a user query is really a challenging task. For this purpose, search engines use different ranking mechanisms on apparently related resultant web documents to decide the order in which documents should be displayed. Existing ranking mechanisms decide on the order of a web page based on the amount and popularity of the links pointed to and emerging from it. Sometime search engines result in placing less relevant documents in the top positions in response to a user query. There is a strong need to improve the ranking strategy. In this paper, a novel ranking mechanism is being proposed to rank the web documents that consider both the HTML structure of a page and the contextual senses of keywords that are present within it and its back-links. The approach has been tested on data sets of URLs and on their back-links in relation to different topics. The experimental result shows that the overall search results, in response to user queries, are improved. The ordering of the links that have been obtained is compared with the ordering that has been done by using the page rank score. The results obtained thereafter shows that the proposed mechanism contextually puts more related web pages in the top order, as compared to the page rank score

Multi-Secondary Transformer: A Modeling Technique for Simulation - II

Patel, A.,Singh, N.P.,Gupta, L.N.,Raval, B.,Oza, K.,Thakar, A.,Parmar, D.,Dhola, H.,Dave, R.,Gupta, V.,Gajjar, S.,Patel, P.J.,Baruah, U.K. Journal of International Conference on Electrical 2014 Journal of international Conference on Electrical Vol.3 No.1

Power Transformers with more than one secondary winding are not uncommon in industrial applications. But new classes of applications where very large number of independent secondaries are used are becoming popular in controlled converters for medium and high voltage applications. Cascade H-bridge medium voltage drives and Pulse Step Modulation (PSM) based high voltage power supplies are such applications. Regulated high voltage power supplies (Fig. 1) with 35-100 kV, 5-10 MW output range with very fast dynamics (${\mu}S$ order) uses such transformers. Such power supplies are widely used in fusion research. Here series connection of isolated voltage sources with conventional switching semiconductor devices is achieved by large number of separate transformers or by single unit of multi-secondary transformer. Naturally, a transformer having numbers of secondary windings (~40) on single core is the preferred solution due to space and cost considerations. For design and simulation analysis of such a power supply, the model of a multi-secondary transformer poses special problem to any circuit analysis software as many simulation softwares provide transformer models with limited number (3-6) of secondary windings. Multi-Secondary transformer models with 3 different schemes are available. A comparison of test results from a practical Multi-secondary transformer with a simulation model using magnetic component is found to describe the behavior closer to observed test results. Earlier models assumed magnetising inductance in a linear loss less core model although in actual it is saturable core made-up of CRGO steel laminations. This article discusses a more detailed representation of flux coupled magnetic model with saturable core properties to simulate actual transformers very close to its observed parameters in test and actual usage.

Investigation of smart multifunctional optical sensor platform and its application in optical sensor networks

Pang, C.,Yu, M.,Gupta, A.K.,Bryden, K.M. Techno-Press 2013 Smart Structures and Systems, An International Jou Vol.12 No.1

In this article, a smart multifunctional optical system-on-a-chip (SOC) sensor platform is presented and its application for fiber Bragg grating (FBG) sensor interrogation in optical sensor networks is investigated. The smart SOC sensor platform consists of a superluminescent diode as a broadband source, a tunable microelectromechanical system (MEMS) based Fabry-P$\acute{e}$rot filter, photodetectors, and an integrated microcontroller for data acquisition, processing, and communication. Integrated with a wireless sensor network (WSN) module in a compact package, a smart optical sensor node is developed. The smart multifunctional sensor platform has the capability of interrogating different types of optical fiber sensors, including Fabry-P$\acute{e}$rot sensors and Bragg grating sensors. As a case study, the smart optical sensor platform is demonstrated to interrogate multiplexed FBG strain sensors. A time domain signal processing method is used to obtain the Bragg wavelength shift of two FBG strain sensors through sweeping the MEMS tunable Fabry-P$\acute{e}$rot filter. A tuning range of 46 nm and a tuning speed of 10 Hz are achieved. The smart optical sensor platform will open doors to many applications that require high performance optical WSNs.