http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Dual-Transmission-Line Microstrip Equiripple Lowpass Filter with Sharp Roll-Off
Vamsi Krishna Velidi,Subrata Sanya 한국전자통신연구원 2011 ETRI Journal Vol.33 No.6
A novel application of a dual-transmission line is proposed to design a lowpass filter (LPF). The proposed structure uses only transmission line elements to produce an equiripple LPF response with sharp roll-off. Design equations are derived using a lossless transmission line model. Controlling the electrical lengths, three transmission-zeros are realized in the stopband to obtain a sharp roll-off rate and wide stopband bandwidth. A single unit microstrip LPF with a 3-dB cut-off frequency at 1.0 GHz having a roll-off of 135 dB/GHz along with a stopband bandwidth of 69.5% is designed for validation.
Vamsi Krishna Kukkapalli,Jin Ho Kim,Sunwoo Kim 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10
Two-phase closed thermosyphons have been employed in roadway embankments in the arctic regions to prevent permafrost from thawing. Thermosyphons installed in the embankment reject heat during the cold season and help maintain the ground temperature below freezing. Despite their proven effectiveness, the use of thermosyphons is limited due to high installation cost. In this research, roadway embankments in permafrost regions were numerically investigated to seek an optimal spacing between neighboring thermosyphons. First, this work focused on the conventional evaporator design of a horizontal straight pipe. Additionally, the constructal theory-inspired Y- and T-shaped evaporators were studied. The volumeaveraged ground temperature was computed for each design. The simulations showed that there exists an optimal spacing and that the proposed Y- and T-shaped designs outperform the conventional design. A Y- and T-shaped design with a higher bifurcation level showed better cooling performance than designs with a single bifurcation level.
Vamsi Krishna Velidi,Subrara Sanyal 한국전자통신연구원 2010 ETRI Journal Vol.32 No.1
This letter presents the design of a compact bandstop filter (BSF) operating at two frequencies. The proposed BSF consists of open-ended stepped impedance resonators (OSIR) and an end-shorted parallel-coupled microstrip line (E-PCML). The OSIRs are used to achieve the impedance-controlled stopband positions. The wide BSF bandwidths are achieved through enhanced coupling of the E-PCML. Explicit design guidelines are derived using a lossless transmission line model. To validate theoretical predictions, a prototype dual-band BSF operating at 900 MHz and 2,100 MHz with fractional bandwidths of 72% and 36%, respectively, is implemented in microstrip.
Microstrip Coupled-Line Lowpass Filter with Wide Stopband for RF/Wireless Systems
Vamsi Krishna Velidi,Subrara Sanyal,Mrinal Kanti Mandal 한국전자통신연구원 2009 ETRI Journal Vol.31 No.3
We present the design of a compact microstrip lowpass filter with a wide stopband which is up to ten times the cutoff frequency. The filter is based on a coupled-line configuration and shunt open stubs. The open stubs create additional transmission zeros, which are used to extend the stopband of the filter without any additional components or cascaded units. A prototype lowpass filter with a 3 dB cutoff frequency of 0.428 GHz and a 15 dB stopband extended up to 4.77 GHz is fabricated to validate the theoretical predictions.
Patient Reported Outcomes from Sacroiliac Joint Fusion
Vamsi K. Kancherla,Shane M. McGowan,Brittany N. Audley,Gbolabo Sokunbi,Steven T. Puccio 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.1
Study Design: Retrospective, case series. Purpose: The purpose of this study is to determine morbidity, complications, and patient reported outcomes from minimally invasive sacroiliac joint (SIJ) fusion. Overview of Literature: Lumbar back pain emanating from the SIJ can be surgically treated via a percutaneous approach in the appropriately selected patient with minimal morbidity and acceptable functional outcomes. Methods: Patients diagnosed by >2 physical examination maneuvers and subjective relief from a computed tomography–guided lidocaine-bupivacaine-steroid injection underwent SIJ fusion after failing conservative management with a combination of oral antiinflammatory medications, physical therapy, and pelvic belt stabilization. Perioperative data collected include estimated blood loss (EBL) and operative time. Oswestry disability index, 12-item short form health survey (SF-12), visual analogue score, and functional status were analyzed. All complications were noted. Results: The study cohort of 45 cases (69% female) achieved postoperative survey follow-up at 9.9 and 32.3 months. SF-12 physical component summary statistically improved while all other scores were equivalent. Mean EBL and operative time were 22 mL and 36 minutes, respectively. Initial survey showed that 64% of patients discontinued narcotics (29/45), 71% do not use an assistive device (32/45), and 15.6% do not work due to pain (7/45). 73% of patients stated they would have the surgery again (33/45). For the second survey, 65% of patients discontinued narcotics (26/40), 70% did not use an assistive device (28/40), and 17.5% did not work due to pain (7/40). A history of thoracolumbar instrumentation (16/45) did not significantly affect outcomes. Three complications described by screw malposition with neurologic deficit (6.7%) were treated with screw repositioning (1 case) and removal of a single superior implant (2 cases) with time to revision of 2.2 months. All three ultimately had resolution of radicular pain. Conclusions: Percutaneous SIJ fusion offers minimal morbidity and acceptable functional outcomes. While women and those with a prior history of lumbar instrumentation may be at increased risk of having SIJ dysfunction requiring surgical intervention, it was not found to affect postoperative functional outcomes when compared to the non-instrumented group.
Bulk electrolysis of Zn-phthalocyanine unveils self assembled nanospheres via anion binding
Narra Vamsi Krishna,Botta Bhavani,Madoori Mrinalini,K.S. Srivishnu,Lingamallu Giribabu,Seelam Prasanthkumar 한국물리학회 2020 Current Applied Physics Vol.20 No.6
Stimuli responsive π-conjugated macrocyclic systems has shown significant attention in organic electronics, however, amongst them, porphyrins and phthalocyanines unveiled remarkable growth towards materials and biological applications. Herein, we report bulk electrolysis of Zn-phthalocyanine system (ZnPc-OMe) under potential difference of 1.5 V in chloroform results anion binding mechanism directs the formation of self-assembled nanospheres by diffusion controlled approach. Electrochemical and UV–Vis absorption studies of ZnPc- OMe suggest that anion (Cl−) binding ability towards ‘Zn‘ whilst applied potential leads to the formation of H+[(Cl)ZnPc-OMe]- promote the enhanced current and charge generation. Microscopic analysis revealed that ZnPc-OMe and H+[(Cl)ZnPc-OMe]- exhibit the nanosheets and spheres with an average diameter of 0.5–1 μm and 300–500 nm, respectively. Powder X-ray diffraction analysis and raman spectra revealed the changes in crystalline phase transitions via ion-dipole and π-π stacking interactions. Thus, these unique features are atypical for phthalocyanine derivative hitherto unknown.
PN Vamsi Kiran,Nikhil Saxena 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.2
Read stability and write ability, or SNM (static noise margin) in total, of a SRAM cell is the effective tool to determine the practicability of the cell. Leakage current, read speed and read stability are few of the constrained parameters desired for any practical SRAM cell. The aim of this paper is to analyze the read behaviour of the multiple SRAM cell structures using cadence tool at 45nm technology and to compare the cells for read operation while keeping the read and write access time and the supply voltage as low as possible. In particular, the leakage currents, leakage power and read behaviour of each SRAM cells are examined . A 10T SRAM cell implementation is proposed here that results in reduced leakage power and leakage current, at the same time with increased read stability in comparision with the conventional 6T SRAM cell as well as 7T, 8T and 9T SRAM cells. As a result, the 10T SRAM always consumes lowest leakage power and leakage current; improve read stability as compared to the 6T, 7T, 8T and 9T SRAM cells. This paper is aimed to reduce the leakage power, leakage current and improve the read behaviour of the different SRAM cell structures using cadence tool at 45nm technology while keeping the read and write access time and the power as low as possible.
Biosorption of chromium onto Erythrina Variegata Orientalis leaf powder
Gannavarapu Venkata Vamsi Aditya,Paladugu Venkateswarlu,Bhagavatula Padma Pujitha,Nalluri Chitti Babu 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.1
The biosorption of chromium from an aqueous solution onto Erythrina Variegata Orientalis leaf powder was investigated in batch operations. The equilibrium agitation time was 180min. The extent of chromium biosorption increased from 74.2% to 86.4% with decrease in biosorbent size from 150 to 45 μm for a dosage of 30 g/L. The biosorption decreased from 99.1 (0.45 mg/g) to 45.5% (1.64 mg/g) with an increase in chromium initial concentration (Co) from 22.5 to 180 mg/L. The extent of biosorption was maximum at pH=3. The experimental data were well explained by Langmuir and Redlich-Peterson isotherm models. The biosorption data followed second-order kinetics with a rate constant of 0.078 g/mg-min for 50 g/L of 45 μm size biosorbent. The biosorption was exothermic and feasible. The biosorption was tending towards irreversibility with increasing temperature.