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排序方式: 共有750条查询结果,搜索用时 15 毫秒
731.
Wireless Personal Communications - In this paper, a triangular complementary split ring resonator (TCSRR) based compact metamaterial antenna for multiband operation is presented. TCSRR is used to... 相似文献
732.
733.
This article presents a simple, compact, and lightweight substrate integrated waveguide (SIW) backed self‐quadruplexing antenna for quad‐band applications. The design procedure is straightforward. Topside of the SIW cavity is modified to form four patches of different lengths which are fed separately by four 50‐Ω microstrip feed lines and operate at 5.14, 5.78, 6.74, and 7.74. It attains 4.1, 4.96, 6.2, and 6.1 peak gain at the above frequencies, respectively. The observed front‐to‐back‐ratio is more than 17.5 dB and the isolation level is above 28 dB. This antenna topology allows to redesign each resonant frequencies as per application requirement using a single parameter and without disturbing other performances. Design guidelines for developing the proposed antenna are provided. A prototype antenna is fabricated using RT‐Duroid (5870) substrate and characterized for validation. The proposed antenna is suitable for handheld microwave devices for C‐band communication. 相似文献
734.
The present study was undertaken to evaluate the effect of dentifrices containing low fluoride concentrations on microhardness of sound enamel in 50 healthy young premolar teeth. They were divided into five different groups according to the concentrations of fluoride in dentifrice used. The Vickers hardness of enamel was measured using a Zwick microhardness tester under 1000 g load and a Vickers indenter before and after the application of fluoride dentifrices. The results of the present study suggest that low fluoride concentration dentifrices are as effective as the higher concentrations in increasing the hardness of enamel. 相似文献
735.
Alharbi F. F. Aman Salma Ahmad Naseeb Ejaz Syeda Rabia Khosa Rabia Yasmin Abbas Sajid Abid Abdul Ghafoor Al-Buriahi M. S. Alrowaili Z. A. Waheed Muhammad Suleman 《Journal of Materials Science: Materials in Electronics》2022,33(15):12147-12156
Journal of Materials Science: Materials in Electronics - Among ferrites materials, M-type hexaferrites are very important due to their excellent technological applications. In the present... 相似文献
736.
Sourabh Bharti Kiran K. Pattanaik 《International Journal of Communication Systems》2016,29(13):2015-2027
Accuracy of sensed data and reliable delivery are the key concerns in addition to several other network‐related issues in wireless sensor networks (WSNs). Early detection of outliers reduces subsequent unwanted transmissions, thus preserving network resources. Recent techniques on outlier detection in WSNs are computationally expensive and based on message exchange. Message exchange‐based techniques incur communication overhead and are less preferred in WSNs. On the other hand, machine learning‐based outlier detection techniques are computationally expensive for resource constraint sensor nodes. The novelty of this paper is that it proposes a simple, non message exchange based, in‐network, real‐time outlier detection algorithm based on Newton's law of gravity. The mechanism is evaluated for its accuracy in detecting outliers, computational cost, and its influence on the network traffic and delay. The outlier detection mechanism resulted in almost 100% detection accuracy. Because the mechanism involves no message exchanges, there is a significant reduction in network traffic, energy consumption and end‐to‐end delay. An extension of the proposed algorithm for transient data sets is proposed, and analytic evaluation justifies that the mechanism is reactive to time series data. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
737.
In this work, the secrecy of a typical wireless cooperative dual-hop non-orthogonal multiple access (NOMA)-enabled decode-and-forward (DF) relay network is investigated with the impact of collaborative and non-collaborative eavesdropping. The system model consists of a source that broadcasts the multiplexed signal to two NOMA users via a DF relay, and information security against the eavesdropper nodes is provided by a helpful jammer. The performance metric is secrecy rate and ergodic secrecy capacity is approximated analytically. In addition, a differential evolution algorithm-based power allocation scheme is proposed to find the optimal power allocation factors for relay, jammer, and NOMA users by employing different jamming schemes. Furthermore, the secrecy rate analysis is validated at the NOMA users by adopting different jamming schemes such as without jamming (WJ) or conventional relaying, jamming (J), and with control jamming (CJ). Simulation results demonstrate the superiority of CJ over the J and WJ schemes. Finally, the proposed power allocation outperforms the fixed power allocation under all conditions considered in this work. 相似文献
738.
Kiran M. Rege 《International Journal of Communication Systems》1995,8(5):313-323
As new broadband networks based on the asynchronous transfer mode (ATM) protocol emerge to support a variety of services, the need for analytical models and tools for sizing network components carrying mixtures of different kinds of traffic will be increasingly felt. This paper presents a simple, yet efficient algorithm for sizing trunks carrying mixtures of constant and variable bit rate traffic. It combines theoretical results for the multi-dimensional Erlang model and the concept of equivalent bandwidth with some heuristic arguments to produce an analytic method for sizing trunks subject to blocking and quality of service constraints for traffic classes. 相似文献
739.
Patruni Kiran P. Srinivasa Rao 《Sensing and Instrumentation for Food Quality and Safety》2016,10(3):411-424
Structural and rheological characterization of reconstituted hydrogels developed from A. vera non-fibrous alcohol insoluble residue (NFAIR) powder using different methods [viz., shaking (S), heating-shaking (HS), and heating (H)] and concentrations (viz., 0.2–1.6 %, w/v) was carried out. Functional group distribution by FTIR spectroscopy and Congo red (CR) method revealed the presence of acetylated acemannan in A. vera powder. Dynamic oscillation studies of A. vera (NFAIR) fluids at all concentrations of 0.2–1.6 %, w/v, showed gel strength in the order of H > HS > S method. However, in H method, increase in concentration from 0.2 to 1.6 %, w/v showed the conformational transition from semi-diluted solution to weak gel nature. Rheological models described the effect of heating temperatures (HT); 30–90 °C, and times (Ht); 15–60 min on viscoelastic behavior in reconstituted A. vera fluids. The reconstituted A. vera hydrogel prepared with a concentration of 1.6 %, w/v using 50 °C (HT) and 30 min (Ht) condition showed a good agreement with the Power law (storage modulus, G′) and Weak gel model (complex modulus, G*) fitted data (R2 > 0.94) resulting higher viscoelastic moduli intercepts; G′0 (71.5 Pa s n′), G″0 (33.5 Pa s n″), lower slopes; n′ (0.22), n″ (0.06), higher network strength (A F , 121.3 Pa s1/z ) and number of network (z, 5.3) values. The obtained results suggested that heating at 50 °C/30 min can develop aqueous weak gel networks of A. vera with enhanced gel strength which may be utilized as a novel gelling agent for wide variety of targeted applications in food and pharmaceutical sectors. 相似文献
740.
Kiran N Bhilegaonkar Adagonda T Sherikar Jayakumar B Khot Umesh D Karkare 《Journal of the science of food and agriculture》1990,51(4):545-553
The characteristics of heat-stable, ethanol-precipitable antigens (BE) of adrenals and muscle tissues of cattle, buffalo, sheep, goat and pig were studied. The antigens were subjected to protein analysis. The distribution patterns of the antigens employing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) as well as polyacrylarnide gel isoelectric focusing revealed that the heat-stable antigens of a dreds contained only one component corresponding to troponin T, whereas muscle BE showed associated low molecular weight components along with troponin T as major component. Negative results of thymol-H2SO4 staining of SDS-PAGE gels indicated that the thermostable antigens did not belong to the mucoprotein class. 相似文献