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101.
In this paper, a fault direction estimation algorithm is proposed for a double-circuit line with thyristor controlled series capacitor (TCSC) using principal component analysis (PCA)-based technique. In case of PCA, an orthogonal transformation is used to convert correlated variables into linearly uncorrelated variables called principal components. Fault in such a compensated line leads to voltage inversion, current inversion, and subsynchronous resonance situations, which affect the performance of the conventional direction estimation process. Transients associated with metal oxide varistor (MOV) operation and control action associated with TCSC, further modulate equivalent impedance of TCSC and MOV combination. In the proposed approach, PCA of angles between positive and negative sequence components of voltage current has been carried out to extract the pattern and to declare the fault direction accurately. The double-circuit line with TCSC is simulated using PSCAD/EMTDC software. The performance of the proposed technique is tested for numerous test cases, and it was found to be accurate. 相似文献
102.
Illumination with solid state lighting technology 总被引:13,自引:0,他引:13
Steigerwald D.A. Bhat J.C. Collins D. Fletcher R.M. Holcomb M.O. Ludowise M.J. Martin P.S. Rudaz S.L. 《IEEE journal of selected topics in quantum electronics》2002,8(2):310-320
High-power light-emitting diodes (LEDs) have begun to differentiate themselves from their more common cousins the indicator LED. Today these LEDs are designed to generate 10-100 lm per LED with efficiencies that surpass incandescent and halogen bulbs. After a summary of the motivation for the development of the high-power LED and a look at the future markets, we describe the current state of high-power LED technology and the challenges that lay ahead for development of a true "solid state lamp." We demonstrate record performance and reliability for high-power colored and white LEDs and show results from the worlds first 100-plus lumen white LED lamp, the solid state equivalent of Thomas Edison's 20-W incandescent lightbulb approximately one century later 相似文献
103.
Priyal Sharma Mahesh Kumar Saini Jagdish Prasad Vinod Singh Gour 《Journal of surfactants and detergents》2019,22(2):403-408
Balanites aegyptiaca (L.) Del. is a widely distributed xerophytic multipurpose tree. The mesocarp of the fruit of B. aegyptiaca has detergent properties due to the presence of saponins. The stability potential of this biosurfactant at varying pH, temperature, and salinity has not been explored so far. In the present study, the relative surface tensions of five different concentrations of the biosurfactant were studied at different temperatures, salinity, and under pH conditions. This study reveals that this biosurfactant retains its activity over a wide range of pH (3–11) and at high salinity (7% NaCl). It is a thermostable cationic surfactant; surfactant activity was recorded even at 100 °C with the lowest relative surface tension of 0.47. High oil displacement (18.00 mm) was observed when studied with petrol. This biosurfactant was found to have a high emulsification index (E24) of 70% with mustard oil. These results indicate that biosurfactant derived from B. aegyptiaca may find use in a wide range of sectors such as textile, food, cosmetics, oil recovery, and healthcare under a wide range of physical and chemical conditions. It offers an efficient, economically viable, and plant-derived alternative to synthetic detergents and adds a way to maintain a sustainable environment. 相似文献
104.
Quaternized poly(phenylene oxide) anion exchange membrane for alkaline direct methanol fuel cells in KOH‐free media 下载免费PDF全文
A series of anion exchange membrane (AEM) electrolytes with quaternary ammonium moiety are fabricated from poly (phenylene oxide) for its application in alkaline direct methanol fuel cells (ADMFCs). In the first step, poly(phenylene oxide) (PPO) is successfully chloromethylated by substituting chloromethyl groups in the aryl position of polymer. In the second step, the chloromethylated PPO (CPPO) is further homogeneously quaternized and ion‐exchanged to form an AEM. From the second step, series of AEMs are prepared by changing the mole ratio of amine in relation to CPPO. The presence of quaternary ammonium group in the membrane was confirmed by elemental analysis. The fabricated membranes are subjected to cell polarization studies in ADMFCs, wherein quaternized poly(2,6‐dimethyl‐1,4‐phenylene oxide) (CPPO:amine of 1:8) membrane exhibits higher peak power density of 3.5 mW cm?2 when compared with the other ratios of CPPO:amine in the absence of KOH solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43693. 相似文献
105.
Kaustubh S. Phanse Aniket Bhat Luiz A. DaSilva 《Journal of Network and Systems Management》2006,14(2):261-278
The ability to dynamically configure mobile ad-hoc network (MANET) devices is critical for supporting complex services such as quality of service (QoS), security and access control in these networks. In our work, we address the problem of policy distribution and provisioning in MANETs. Previously, we have proposed a policy provisioning architecture that enables the operator, e.g., a military command and control center, to maintain a logically centralized control of the network as a whole, while allowing a physically decentralized and self-managing implementation essential for a MANET environment. In this paper, we present an analytical model of the availability of the policy distribution service in a MANET and analyze the performance using stochastic Petri nets (SPNs). We develop the model at two levels of complexity: as a simple Markovian model with Poisson assumptions and as a more accurate non-Markovian model with general distributions obtained using statistical parameterization. We compare and cross-validate the analytical results with simulation and experimental results. Finally, we illustrate the effectiveness of the architecture for managing QoS for soft real-time applications, using an emulated mobile ad-hoc network testbed. 相似文献
106.
M. I. Bhat 《Journal of Petroleum Geology》1983,5(4):389-400
Carbonate deposition through the Earth's history shows two distinct changes in terms of volume and chemistry. Whereas carbonates comprise a very small percentage of the total sedimentary rocks in the Proterozoic, they constitute 20–25% at the present time. From the Archaean to Early Palaeozoic, carbonates are dominantly dolomites, whereas afterwards they are dominantly limestone. 87 Sr/86 Sr, δ18 0 and δ13 C trends show an increase with decreasing age.
All these features of carbonate rocks are explicable as being related to the increased episodic outgassing of CO2 and CH4 from the upper mantle throughout the Earth's history.
The Mesozoic carbonates of Himalaya are correlatable with the CO2 outgassing associated with rifting and magmatism during the birth of the Tethys ocean. 相似文献
All these features of carbonate rocks are explicable as being related to the increased episodic outgassing of CO
The Mesozoic carbonates of Himalaya are correlatable with the CO
107.
Sneha M. Kumar A. Keerthan Hegde Nikhil V. Anish A. S. Shobha G. 《International Journal of Information Security》2023,22(6):1881-1891
International Journal of Information Security - Software-defined networks (SDN) are no more a new technology as many industries are adopting it in a hybrid or full stack mode. SDN has already... 相似文献
108.
The mountain clustering method and the subtractive clustering method are useful methods for finding cluster centers based on local density in object data. These methods have been extended to shell clustering. In this article, we propose a relational mountain clustering method (RMCM), which produces a set of (proto) typical objects as well as a crisp partition of the objects generating the relation, using a new concept that we call relational density. We exemplify RMCM by clustering several relational data sets that come from object data. Finally, RMCM is applied to web log analysis, where it produces useful user profiles from web log data. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 375–392, 2005. 相似文献
109.
Multimedia Tools and Applications - Cryptography is the process by which a readable message is converted into cipher-text unintelligible to an eavesdropper. With the advent of the internet,... 相似文献
110.
Several power system networks exhibit bifurcation, chaos and instability behavior for some specific values of initial conditions and parameters. Angle and voltage instability behavior of power system is prone to such specific values and parameter variation. This paper proposes fractional order proportional integral controller (FOPI) based state feedback for precise and robust control of such undesirable behavior. This paper proposes first ever use of FOPI for precise rotor angle control leading to instability in power system dynamic behavior. FOPI controller is applied on generator connected to IEEE‐14 bus benchmark model. The ripple frequency of turbine torque is chosen as one of the cause of instability behavior of power system, which has the potential possibility to push system behavior to chaos and instability mode. The proposed FOPI controller design will inhibit the dynamic behavior of power system to safe and stable bounds. Proposed strategy can be applied to other large power system models as well due to its simplicity in design philosophy. Several phase plane trajectories with and without FOPI controller are used to support the viewpoint. 相似文献