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Search Results: 1 - 10 of 327441 matches for " V. C.; "
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Steel Catenary Riser Fatigue Life Prediction Using Linearized Hydrodynamic Models  [PDF]
C. Ebunuoha, C. V. Ossia
World Journal of Engineering and Technology (WJET) , 2017, DOI: 10.4236/wjet.2017.54048
Abstract: Steel catenary risers, (SCR) usually installed between seabed wellhead and floating platform are subjected to vortex shedding. These impose direct forces, hence cyclic stresses, and fatigue damage on the SCR. Riser failure has both economic and environmental consequences; hence the design life is usually greater than the field life, which is significantly reduced by vortex induced vibration (VIV). In this study, SCR and metOcean data from a field in Offshore Nigeria were substituted into linearized hydrodynamic models for simulations. The results showed that the hang off and touchdown regions were most susceptible to fatigue failure. Further analysis using Miner-Palm green models revealed that the fatigue life reduced from a design value of 20-years to 17.04-years, shortened by 2.96-years due to VIV. Furthermore, a maximum wave load of 5.154 kN was observed. The wave loads results corroborated with those obtained from finite element Orca Flex software, yielding a correlation coefficient of 0.975.
A Low Power and High Speed Viterbi Decoder Based on Deep Pipelined, Clock Blocking and Hazards Filtering  [PDF]
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.26064
Abstract: A high speed and low power Viterbi decoder architecture design based on deep pipelined, clock gating and toggle filtering has been presented in this paper. The Add-Compare-Select (ACS) and Trace Back (TB) units and its sub circuits of the decoder have been operated in deep pipelined manner to achieve high transmission rate. The Power dissipation analysis is also investigated and compared with the existing results. The techniques that have been employed in our low-power design are clock-gating and toggle filtering. The synthesized circuits are placed and routed in the standard cell design environment and implemented on a Xilinx XC2VP2fg256-6 FPGA device. Power estimation obtained through gate level simulations indicated that the proposed design reduces the power dissipation of an original Viterbi decoder design by 68.82% and a speed of 145 MHz is achieved.
How and Why Do Gestational Trophoblastic Neoplasms Overproduce Human Chorionic Gonadotropin?  [PDF]
C. V. Rao
Open Journal of Obstetrics and Gynecology (OJOG) , 2015, DOI: 10.4236/ojog.2015.51001

From the published data, the present mini-review attempts to answer two fundamental questions about the gestational trophoblastic neoplasms. In addition, it extrapolates the findings to other cancers that produce small amounts of hCG and how a novel therapies could be developed.

An Integrated Drive for Two PMSMs Involved Automotive Applications and Development of Current Reference Expanded Two Arm Modulation Technique  [PDF]
V. Krishnakumar, V. Kamaraj, C. Adrien Perianayagam
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78155
Abstract: A five leg inverter (FLI) control is incorporated to drive two independent rated permanent magnet synchronous motors (PMSMs) for automotive applications. Literature evidences many attempts of employing the FLI for controlling two general purpose/special motors, where variety of modulation techniques has been practiced for performance enhancement. Also in these cases one leg of inverter is common to both the motors. The expanded two arm modulation (ETAM) has been generally engaged in FLI. In ETAM the percentage voltage utilization factor (VUF) is calculated based on “αmax”, where “αmax” is the maximum modulation index and equal to?and hence it restricts the VUF to 50%. This makes the FLI drives to use the dc link in inefficient way, which is due to the fact that conventional ETAM works with voltage reference. This paper modifies the ETAM in an ingenious way to improve the VUF further through current reference. In addition, the developed current reference expanded two arm modulation (CRETAM) minimizes the current harmonics and torque ripple as well. A detailed comparison of the CRETAM with the conventional ETAM and the competent digital counterpart, space vector pulse width modulation (SVPWM), is also presented. The enhancement in VUF, torque ripple minimization and current total harmonic distortion (THD) reduction are found in the MATLAB based simulation results.
Performance Metric of Z Source CHB Multilevel Inverter FED IM for Selective Harmonic Elimination and THD Reduction  [PDF]
V. Maheswari, V. Nandagopal, C. Kannan
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.711317
Abstract: This paper focuses on a Z source cascaded multilevel inverter which is designed to minimize harmonics in the output voltage. A balanced dc-link peak voltage can be achieved. The power generation module is built by PV panels which are connected to Z-Source Cascade H-bridge inverter. Cascaded multilevel inverter can achieve the distributed maximum power point tracking to increase the system efficiency and achieve high voltage/high power grid tie without a transformer. This paper analyzes the different PWM switching scheme and the operating states of a ZSI module and comparison is made with different PWM and total harmonic distortion of various PWM schemes.
Effect of Y on the Properties of Sm-Doped Ceria for IT-SOFC Applications  [PDF]
V. Venkatesh, C. Vishnuvardhan Reddy
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.411181

The co-doped ceria-based materials with general composition formula Ce0.8-xYxSm0.2O2-δ (x = 0, 0.02, 0.04, 0.06) were prepared through the sol-gel method. The single phase of the prepared materials was confirmed by X-ray diffraction (XRD). The lattice parameters were determined by least square fitting of UNIT CELL programme. The linear variation of lattice parameter with concentration of Y into the samarium doped ceria (SDC) indicates the validity of Vegard’s law. The crystallite size of the samples obtained by using of Scherrer formula is in the range from 34 nm to 49 nm. The thermal expansion studies were carried out by using dilatometric technique in the temperature range from room temperature to 1000°C. It was observed that the thermal expansion increased linearly with increasing temperature for all the samples. The electrical conductivity was studied using impedance spectroscopy. It was observed that the composition Ce0.74Y0.06Sm0.2O2-

Sinonasal Undifferentiated Carcinoma—A Case Report  [PDF]
C. Aparna, I. V. Renuka
International Journal of Otolaryngology and Head & Neck Surgery (IJOHNS) , 2014, DOI: 10.4236/ijohns.2014.36068
Abstract: Sinonasal tumors with neuroendocrine differentiation are uncommon. They arise from schneiderian epithelium. The authors reported a case in a fifty-six years old female patient who came with complaints of headache and epistaxis. Differential diagnosis and review of literature are presented in detail. This case is presented in view of its rarity.
Optimization of Friction and Wear Behaviour in Hybrid Metal Matrix Composites Using Taguchi Technique  [PDF]
V. C. Uvaraja, N. Natarajan
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2012, DOI: 10.4236/jmmce.2012.118063
Abstract: Al-7075 alloy-base matrix, reinforced with mixtures of silicon carbide (SiC) and boron carbide (B4C) particles, know as hybrid composites have been fabricated by stir casting technique (liquid metallurgy route) and optimized at different parameters like sliding speed, applied load, sliding time, and percentage of reinforcement by Taguchi method. The specimens were examined by Rockwell hardness test machine, Pin on Disc, Scanning Electron Microscope (SEM) and Optical Microscope. A plan of experiment generated through Taguchi’s technique is used to conduct experiments based on L27 orthogonal array. The developed ANOVA and the regression equations were used to find the optimum wear as well as co-efficient of friction under the influence of sliding speed, applied load, sliding time and percentage of reinforcement. The dry sliding wear resistance was analyzed on the basis of “smaller the best”. Finally, confirmation tests were carried out to verify the experimental results.
Influence of Ethylene Inhibitor Silver Nitrate on Direct Shoot Regeneration from in Vitro Raised Shoot Tip Explants of Sphaeranthus indicus Linn.—An Important Antijaundice Medicinal Plant  [PDF]
K. Harathi, C. V. Naidu
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.73046
Abstract: In the present investigation, an attempt has been made to study the influence of ethylene inhibitor silver nitrate on direct shoot regeneration in Sphaeranthus indicus, an important antijaundice medicinal plant, by using in vitro raised shoot tip explants. The effect of various concentrations of kinetin, BAP (0.5 - 3.0 mg/l), and NAA (0.1 - 0.5 mg/l) along with AgNO3 (0.1 - 1.0 mg/l) was studied. Among the combinations tested MS medium augmented with kinetin (1.0 mg/l), NAA (0.1 mg/l) and AgNO3 (0.4 mg/l) was found to be optimum for production of multiple shoots (34.3 ± 0.36). Addition of AgNO3 to the media not only increases shoot number in all the concentrations tested but also shoot length. AgNO3 at the concentration of 0.4 mg/l produced 35% more number of multiple shoots when compared to multiple shoots (10.8 ± 0.12) produced in control. In the present study by the addition of ethylene inhibitor silver nitrate and growth regulators, more number of multiple shoots (three folds) and shoot length was observed compared to control. These in vitro raised shoots were transferred to the rooting medium containing different concentrations of auxins such as NAA and IAA along with AgNO3 (0.1 - 0.6 mg/l). Better rooting response (21.6) was observed on NAA (2.0 mg/l) and AgNO3 (0.4 mg/l) containing media. The healthy rooted plantlets were transferred to polybags containing soil and vermiculate in 1:1 ratio for hardening. Finally the hardened plants were transferred to field environment for utmost survivability.
A proposed model for understanding human-bacterial interactions: Space-time approach on community Escherichia coli occurrence and resistance phenomenon  [PDF]
Carlos R. V. Kiffer, Antonio M. V. Monteiro, Eduardo C. G. Camargo, Antonio C. C. Pignatari
Advances in Bioscience and Biotechnology (ABB) , 2013, DOI: 10.4236/abb.2013.44066
Abstract: Due to ecological effect, it is expected that population exposures to antimicrobial drugs may lead to microorganisms’ modifications, occasionally leading to resistance emergence. The present review was based on previous empirical data and on related literature search for quantitative empirical models exploring the human-bacterial interactions. Our previous studies have shown the emergence of ciprofloxacin resistant (CIP-R) Escherichia coli significantly related to previous specific levels of ciprofloxacin consumption and to urban clusters of CIP-R E. coli. The evidence of significant spatial clustering of antimicrobial resistance (ciprofloxacin resistance E. coli) reinforces the ecological effect hypothesis as a major drive in resistance emergence. In other words, human populations submitted to a certain ciprofloxacin or quinolone usage level may affect neighbours within certain geographical areas, not necessarily due to individual antimicrobial intake, but as a driving pressure over a modified circulating E. coli population. Apparently quantitative spatial-temporal analytical frameworks may be better for understanding human-bacterial interactions based on any of their epiphenomena (antimicrobial consumption, antimicrobial resistance, geno/phenotypic characteristics).
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