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排序方式: 共有183条查询结果,搜索用时 15 毫秒
1.
Jonathan Keller Damian Carr Frances Love Paul Grabill Hieu Ngo Perumal Shanthakumaran 《Journal of Intelligent Manufacturing》2012,23(2):205-211
The US Army has launched an aggressive program to implement condition based maintenance on its rotary wing assets. Condition
Based Maintenance takes advantage of technology developments in the areas of machinery monitoring, signal processing and fault
modeling to reduce the cost of ownership through improved maintenance procedures. Documenting the reduction in maintenance
burden, cost savings and increased safety through early detection of helicopter faults is an important step in justifying
the program. This paper describes a novel technique used to detect a serious fault in the accessory section of the AH-64D
Apache main transmission. The technique determines if the primary or secondary clutch system is driving the aircraft accessories
through a tachometer speed ratio. The method has identified three aircraft operating on the secondary system allowing Army
maintenance crews to replace the affected transmissions and quickly restore the aircraft to operational status. 相似文献
2.
This article proposes a wind velocity sensorless hill-climb searching algorithm in the grid-connected field-oriented controlled permanent magnet synchronous generator based wind energy conversion system. The proposed method improves the speed and accuracy of initial tracking. Pseudo-optimum points are used to track the exact optimum points using the power versus speed characteristics of a wind turbine for various wind velocities. This research emphasizes that the pseudo-optimum points using the power versus speed characteristics are always less than and much nearer to the exact optimum points. The small-step forward tracking after pseudo-optimum points improves the accuracy of this algorithm. Moreover, this method improves the tracking speed for various wind velocities. The system used for this research consists of a back-to-back sinusoidal pulse-width modulation converter between the generator and the grid. The performance of the proposed method is analyzed mathematically and verified by simulation using MATLAB/Simulink software (The Mathworks, Natick; Massachusetts, USA). 相似文献
3.
Markus Fröbel Ajay Perumal Tobias Schwab Malte C. Gather Björn Lüssem Karl Leo 《Organic Electronics》2013,14(3):809-813
We report efficient and bright organic light-emitting devices operated by capacitive energy coupling. In this approach, the organic layers are enclosed between sputter-deposited hafnium dioxide layers to prevent charge carrier injection. When a sinusoidal voltage signal is applied to the electrodes, the devices emit bright green light whereas no detectable emission is generated upon application of a constant voltage. The efficiency of the process depends heavily on the frequency of the applied voltage signal. By optimizing the driving scheme, a record luminous efficacy for AC driven OLEDs of 2.7 lm/W at 500 cd/m2 is achieved. 相似文献
4.
Maniyazagan Munisamy Hyeon-Woo Yang Naveenkumar Perumal Nayoung Kang Woo Seung Kang Sun-Jae Kim 《International journal of molecular sciences》2022,23(8)
The most pressing concerns in environmental remediation are the design and development of catalysts with benign, low-cost, and efficient photocatalytic activity. The present study effectively generated a flower-like indium oxide (In2O3-MF) catalyst employing a convenient MOF-based solvothermal self-assembly technique. The In2O3-MF photocatalyst exhibits a flower-like structure, according to morphology and structural analysis. The enhanced photocatalytic activity of the In2O3-MF catalyst for 4-nitrophenol (4-NP) and methylene blue (MB) is likely due to its unique 3D structure, which includes a large surface area (486.95 m2 g−1), a wide spectrum response, and the prevention of electron–hole recombination compared to In2O3-MR (indium oxide-micro rod) and In2O3-MD (indium oxide-micro disc). In the presence of NaBH4 and visible light, the catalytic performances of the In2O3-MF, In2O3-MR, and In2O3-MD catalysts for the reduction of 4-NP and MB degradation were investigated. Using In2O3-MF as a catalyst, we were able to achieve a 99.32 percent reduction of 4-NP in 20 min and 99.2 percent degradation of MB in 3 min. Interestingly, the conversion rates of catalytic 4-NP and MB were still larger than 95 and 96 percent after five consecutive cycles of catalytic tests, suggesting that the In2O3-MF catalyst has outstanding catalytic performance and a high reutilization rate. 相似文献
5.
Christina Jane Vellan Jaime Jacqueline Jayapalan Boon-Koon Yoong Azlina Abdul-Aziz Sarni Mat-Junit Perumal Subramanian 《International journal of molecular sciences》2022,23(4)
Pancreatic ductal adenocarcinoma (PDAC), a highly aggressive malignancy with a poor prognosis is usually detected at the advanced stage of the disease. The only US Food and Drug Administration-approved biomarker that is available for PDAC, CA 19-9, is most useful in monitoring treatment response among PDAC patients rather than for early detection. Moreover, when CA 19-9 is solely used for diagnostic purposes, it has only a recorded sensitivity of 79% and specificity of 82% in symptomatic individuals. Therefore, there is an urgent need to identify reliable biomarkers for diagnosis (specifically for the early diagnosis), ascertain prognosis as well as to monitor treatment response and tumour recurrence of PDAC. In recent years, proteomic technologies are growing exponentially at an accelerated rate for a wide range of applications in cancer research. In this review, we discussed the current status of biomarker research for PDAC using various proteomic technologies. This review will explore the potential perspective for understanding and identifying the unique alterations in protein expressions that could prove beneficial in discovering new robust biomarkers to detect PDAC at an early stage, ascertain prognosis of patients with the disease in addition to monitoring treatment response and tumour recurrence of patients. 相似文献
6.
John D. Rodney S. Deepapriya M. Cyril Robinson C. Justin Raj Suresh Perumal Byung Chul Kim S. Krishnan S. Jerome Das 《International Journal of Hydrogen Energy》2021,46(54):27585-27596
The production of hydrogen, a favourable alternative to an unsustainable fossil fuel remains as a significant hurdle with the pertaining challenge in the design of proficient, highly productive and sustainable electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, the dysprosium (Dy) doped copper oxide (Cu1-xDyxO) nanoparticles were synthesized via solution combustion technique and utilized as a non-noble metal based bi-functional electrocatalyst for overall water splitting. Due to the improved surface to volume ratio and conductivity, the optimized Cu1-xDyxO (x = 0.01, 0.02) electrocatalysts exhibited impressive HER and OER performance respectively in 1 M KOH delivering a current density of 10 mAcm?2 at a potential of ?0.18 V vs RHE for HER and 1.53 V vs RHE for OER. Moreover, the Dy doped CuO electrocatalyst used as a bi-functional catalyst for overall water splitting achieved a potential of 1.56 V at a current density 10 mAcm?2 and relatively high current density of 66 mAcm?2 at a peak potential of 2 V. A long term stability of 24 h was achieved for a cell voltage of 2.2 V at a constant current density of 30 mAcm?2 with only 10% of the initial current loss. This showcases the accumulative opportunity of dysprosium as a dopant in CuO nanoparticles for fabricating a highly effective and low-cost bi-functional electrocatalyst for overall water splitting. 相似文献
7.
This work is concerned with the application of the thermal lattice Boltzmann method (TLBM) to compute incompressible two- and three-dimensional flows in cavities. Two convection test cases, namely, the laminar flow in a differentially heated square cavity and a cubic cavity, are numerically analyzed through TLBM. The internal energy density distribution function approach with two three-dimensional particle velocity models, namely, the 15-velocity and the 19-velocity, and a two-dimensional model, namely, the nine-velocity, have been used in the present work. Computations are carried out for laminar flows in a differentially heated square cavity and a cubical cavity (Rayleigh numbers = 103 to 105). The boundary conditions used are stable and of good accuracy. To lend credibility to the thermal lattice Boltzmann model square cavity results, they are further compared with those obtained from a finite-difference-based code developed for this purpose. 相似文献
8.
Perumal Siddhuraju Klaus Becker 《Journal of the science of food and agriculture》2003,83(14):1517-1524
The antioxidant activities of a methanolic extract of mucuna beans (Mucuna pruriens var utilis) and several non‐protein amino/imino acids, namely L ‐3,4‐dihydroxyphenylalanine (L ‐dopa), L ‐3‐carboxy‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline (compound I), (?)‐1‐methyl‐3‐carboxy‐6,7‐dihydroxy‐1,2,3,4‐tetrahydroisoquinoline (compound II) and 5‐hydroxytryptophan (5‐HTP), were evaluated. By virtue of their hydrogen‐donating ability, all the tested compounds and the mucuna seed extract showed excellent reducing power, with the highest values being recorded for L ‐dopa in a dose‐dependent manner. Similarly, as compared with synthetic antioxidants (BHT and BHA) and quercetin, all the tested compounds and the seed extract were found to be more potent in free radical‐scavenging activity (P < 0.05) against α,α‐diphenyl‐β‐picrylhydrazyl (DPPH?) radicals. Hydroxyl radicals (OH?) and superoxide anion radicals (O2??) were effectively scavenged by the tested compounds, with the exception that no scavenging activity of 5‐HTP was observed on (O2??) up to a concentration of 2 mg ml?1, as was also the case for BHA. Among the tested non‐protein amino/imino acids and seed extract the highest peroxidation‐inhibiting activity (95%) was recorded for 5‐HTP. On the other hand, in the linoleic acid/β‐carotene‐bleaching system, L ‐dopa, compound I and compound II acted as pro‐oxidants, whereas the seed extract showed only weak antioxidant activity as in the linoleic acid emulsion system. Copyright © 2003 Society of Chemical Industry 相似文献
9.
10.
Muthupandi Nagaraj Devanathan Perumal Muthusamy Boominathan Nattamai Bhuvanesh 《Journal of Sulfur Chemistry》2014,35(1):24-30
The attempted selenium dioxide oxidation of substituted diphenacyl sulfides in anticipation of further functionalization led to a series of α -ketoacids 3 via oxidation followed by C?S bond cleavage. Two minor products, 5 and 6, have also been isolated and a mechanistic pathway for the formation of 3, 5 and 6 has been proposed. 相似文献