A high efficiency on‐chip reconfigurable Doherty power amplifier for LTE communication cells

Kumar, Rajesh,Kanuajia, Binod Kumar,Dwari, Santanu,Kumar, Sandeep,song, Hanjung John Wiley Sons, Inc. 2018 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.60 No.10

<P><B>Abstract</B></P><P>In this paper, a high efficiency on‐chip reconfigurable Doherty power amplifier (DPA) with proposed topology is proposed for LTE or 4G communication cells. The proposed DPA consists of input driver topology, hybrid coupler, asymmetric amplifiers, and 1:1 balun filtered network. The proposed input driver circuit provides wide amplified signal operation within range of 2.3GHz to 6GHz with flat gain of 33 dB. The amplified signal is unsteadily divided into two paths toward the carrier and the power amplifier by 90<SUP>0</SUP> hybrid couplers and demonstrates 27.6 dB and 28.3 dB of gain along with 83.2% and 84.5% of power added efficiency at average output power of 40 dBm. The high efficiency and almost flatness in gain stability of proposed DPA providing better solution in order to overcome the interference and the broadband issues for LTE communication cells. The balun‐filtered network is employed for combined the two outputs of carrier and peak amplifiers that provides more uniform desired band of operation in the frequency responses. The proposed DPA circuit are implemented and optimized by using advanced design RF simulator platform. The fabricated chip is made by using 0.13 μm GaN HEMT on Si‐Nitride monolithic microwave integrated circuit die process. The fabricated chip of DPA provides 85% of PAE with 28 dB gain which are made close agreement with simulation results. The size of chip is 2.8*1.2mm<SUP>2</SUP> which occupies less die area as compared to existing DPAs.</P>

Parametric resonance of composite skew plate under non-uniform in-plane loading

Rajesh Kumar,Abhinav Kumar,Sarat Kumar Panda 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.2

Parametric resonance of shear deformable composite skew plates subjected to non-uniform (parabolic) and linearly varying periodic edge loading is studied for different boundary conditions. The skew plate structural model is based on higher order shear deformation theory (HSDT), which accurately predicts the numerical results for thick skew plate. The total energy functional is derived for the skew plates from total potential energy and kinetic energy of the plate. The strain energy which is the part of total potential energy contains membrane energy, bending energy, additional bending energy due to additional change in curvature and shear energy due to shear deformation, respectively. The total energy functional is solved using Rayleigh-Ritz method in conjunction with boundary characteristics orthonormal polynomials (BCOPs) functions. The orthonormal polynomials are generated for unit square domain using Gram- Schmidt orthogonalization process. Bolotin method is followed to obtain the boundaries of parametric resonance region with higher order approximation. These boundaries are traced by the periodic solution of Mathieu-Hill equations with period T and 2T. Effect of various parameters like skew angle, span-tothickness ratio, aspect ratio, boundary conditions, static load factor on parametric resonance of skew plate have been investigated. The investigation also includes influence of different types of linearly varying loading and parabolically varying bi-axial loading.

Investigation of Ionic Transport Through Track-Etched Conical Nanopores of PET Membrane

Sushil Kumar,Rajesh Kumar,Sushil Kumar,Narinder Kumar,S. K. Chakarvarti 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.1

The control of ionic transportation inside the multi asymmetric conical nanopores in polyethylene terephthalate (PET) membrane was investigated. The conical nanopores were prepared by chemical etching in irradiated PET foil using etchant (9 M NaOH) and stopping solution (1 M NaCl + 1 M HCOOH). The behavior of ionic current was recorded under stepping voltage - 2 V to +2 V at different molar concentrations of potassium halides (KCl, KBr and KI) under symmetric bathing condition in electrochemical cell. It is found that the presence of multiple ionic species and the occurrence of counterion condensation of charge regulated polyelectrolyte play an effective role in ionic current rectification (ICR). The electrical conductance of conical nanopores may be estimated by measuring the ionic current rectification properties of track-etched nanopores. The charge transport properties vary with molar concentration and pH of electrolyte. Moreover, ICR may be used as a voltage gating phenomena with wide technological applications.

Heat Flux Measurements in High Velocity Oxygen-Fuel Torch Flow for Testing High Thermal Materials

Rajesh Kumar Chinnaraj,Seong Man Choi(최성만),Seong Min Hong(홍성민) 한국추진공학회 2020 한국추진공학회 학술대회논문집 Vol.2020 No.7

고열 재료를 시험평가 하기 위한 HVOF 흐름에서 가든 게이지(Gardon gauge)를 이용하여 열유속을 측정하였다. 노즐 출구로부터 4 개의 다른 위치에서 열유속 측정을 수행하였다. 실험 중 가든 게이지를 수냉시켰다. 유효한 가정을 적용하여 열량 열유속(Calorimetric heat flux)을 계산하고 가든 게이지의 열유속 측정 결과와 잘 일치하는 것으로 나타났으며, 따라서 서로를 검증했습니다. A Gardon gauge was used to measure heat fluxes in a HVOF flow intended for testing high thermal materials. The measurements were taken at four different locations from the nozzle exit. The Gardon gauge was water cooled during the experiments. Applying valid assumptions, the calorimetric heat fluxes were calculated and were shown to be in good agreement with Gardon gauge heat flux results, thus validating each other.

Rare Earths Recovery from Waste Permanent Magnets (WPMs) by Hydrometallurgical Methods

( Rajesh Kumar Jyothi ),( Jin-young Lee ),( Kyeong Woo Chung ),( Jong Hyuk Jeon ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

Rare earths are a series of 17 elements (the lanthanides, yttrium, and scandium) which are key components in the current lifestyle. Those metals have multiple applications in different areas especially in the electrical and electronics fields alongside being key materials for green energy production. To recover rare earths from primary (ores) and secondary sources (scraps, spent magnets, etc.) the economically sound and most convenient technology involves liquid- liquid extraction. Several countries, such as South Korea, lack of primary sources of these important metals, therefore they must recur to recycling -or importation (fluctuating depending on the market supply and demand)- to fulfill the demand necessary for their growing high-tech industries, dedicated primarily to the manufacture of electrical and electronic items used in the daily life. In addition, after electronic and industrial goods are used they must be discarded usually in landfills, which in small countries with high population density is a great economic, social and environmental burden. The countries with the highest population densities according to the economic co-operation and development (OECD) organization records (year 2012) are South Korea, The Netherlands, Belgium, Israel, Japan, UK, Germany, Luxemburg, Italy and Switzerland (http://www.un.org/en/development/desa/population/publications/trends/wpp2012. The market trade of rare earths is a monopoly controlled by China, followed by a small supply from India, Australia, Malaysia, Brazil, USA and Russia. China’s monopoly of the RE trade can be seen as detrimental for the free economy of these goods having applications widely in the metallurgy, permanent magnets, electronics, fabrication of household items, glass, alloys, petroleum refining catalysts, among others. The major rare earth consuming industrial products are magnets 26%, metal alloys 19%, polishing 16.5%, catalysts 15%, glass/phosphors 6% and ceramics/others 5.5%, which shows the necessity of an industrial and economically feasible process to recover REEs from waste or secondary resources. The Department of Energy in the United States recognize four elements as critical due to their multiple industrial applications: neodymium, praseodymium, dysprosium and terbium. When talking about green economy, the first option that must be considered is the minimization of the consumption of the elements or the minimization of waste production. The second option to be considered is the reuse, recycling and recovery of the waste produced in the fabrication process of consumer products. Finally, the least favored option is the disposal of waste, which must overcome the landfill challenge. By reusing and recycling rare earth elements from secondary sources the national demand of these metals can be reached without consuming primary resources and having and environmental friendly process.

Functions of Nitric Oxide and Superoxide Anion in the Growth and Antioxidant Enzyme Activity of Adventitious Roots of Panax ginseng C.A. Mayer

Rajesh Kumar Tewari,Eun-Joo Hahn,Kee-Yoeup Paek 한국원예학회 2007 한국원예학회 학술발표요지 Vol.2007 No.6

Molecular fossils “pseudogenes” as functional signature in biological system

Rajesh Kumar Singh,Divya Singh,Arpana Yadava,Akhileshwar Kumar Srivastava 한국유전학회 2020 Genes & Genomics Vol.42 No.6

Pseudogenes have been known as non-functional molecular relics developed from inactivated genomic mutations while evolution. However, they have a various function at distinct molecular stages (DNA, RNA and protein) in different biological events including in cancer and associated with parental-gene-dependently and parental-gene independently. The interactions of pseudogenes with ancestor genes or other genes alter in their sequences and transcriptional processes. Pseudogene of RNA sequences have multiple functions in post-transcriptional activities as antisense RNAs, endogenous small-interference RNAs, and competing endogenous RNAs. Moreover, it also plays vital roles in controlling of its parent genes and other pseudogenes transcribing into RNA. Pseudogene transcripts make small interfering RNA or decline cellular miRNA level. The current review focuses on pseudogene functional signature in human genome by regulating the gene expression.

Application and Environmental Risks of Livestock Manure

Kumar, Ramasamy Rajesh,Park, Bong Ju,Cho, Jae Young The Korean Society for Applied Biological Chemistr 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.6

Over the past few decades, livestock production has undergone an industrial revolution, resulting in the large-scale generation of livestock manure. Livestock manure has many beneficial nutrients, which can improve agricultural crop production, and is an organic alternative to chemical fertilizers. Livestock manure requires proper treatment before application to agricultural land, because it contains toxic heavy metals and pathogenic microorganisms. When improperly treated, stored or used, livestock manure can pollute rivers, soil ecosystems, and underground drinking water, thereby affecting all living organisms nearby. In this article, we illustrate the land applications and environmental risks associated with the use of livestock manure.

Performance Prediction and QoS Based Resource Selection in Grid

Rajesh Kumar Bawa,Mr. Gaurav Sharma 보안공학연구지원센터(IJGDC) 2012 International Journal of Grid and Distributed Comp Vol.5 No.3

Are exchange rates interdependent? Evidence using wavelet analysis

Kumar, Satish,Pathak, Rajesh,Tiwari, Aviral Kumar,Yoon, Seong-Min Taylor Francis 2017 Applied Economics Vol.49 No.33