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81.
Abdullah Al-Hadi Azremi Janne Ilvonen Risto Valkonen Jari Holopainen Outi Kivekäs Clemens Icheln Pertti Vainikainen 《International Journal of Wireless Information Networks》2011,18(3):146-157
This paper presents a comprehensive simulation study on the performance of coupling element-based dual-antenna structures
on a mobile terminal at the 2,000 MHz Universal Mobile Telecommunications System (UMTS) frequency band with varying two significant
hand effects; vertical position of hand along terminal chassis, and distance between hand palm and terminal chassis. The results
reveal that in uniformly distributed isotropic environment, there exists a gain imbalance between antenna elements due to
hand effects and it is shown that a gain imbalance of 3.7 dB lead to a reduction of 1.9 dB in diversity gain at 99% reliability
level using maximal ratio combining (MRC) technique. For a dual-antenna configuration, the impact of gain imbalance on diversity
gain is more significant when only one antenna element is in close proximity to the hand, compared to when both antenna elements
are in the presence of the hand. It is also shown that a dual-antenna structure with elements vertically oriented along the
edges of a small 100 mm × 40 mm mobile terminal chassis achieves better performance in port-to-port isolation, gain imbalance
and diversity gain compared to other studied dual-antenna configurations when the user’s hand is present. 相似文献
82.
We consider infrastructure-based amplify-and-forward (AF) relaying for extending downlink and uplink coverage areas of a cellular
base station. The base station serves multiple mobile users via a multi-hop backhaul relay link by sharing out access link
channel resources with maximum signal-to-noise ratio (SNR) scheduling. We analyze the performance of the system by deriving
closed-form expressions for outage probability, outage capacity, ergodic capacity, average end-to-end SNR and amount of fading
(AoF). These measures show that maximum SNR scheduling of multiple users in a cellular relay link offers significant diversity,
capacity and SNR improvement over single-user transmission and round robin scheduling. We also relate performance of the relay
link to that of a distributed antenna system (DAS), and show that the noisy wireless backhaul relay link induces tolerable
performance deterioration compared to deploying a cable-connected distributed antenna. 相似文献
83.
A measurement method and apparatus was developed to measure continuously toxic metal compounds in industrial water samples. The method was demonstrated by using copper as a sample metal. Water was injected into the sample line and subsequently into a nitrogen plasma jet, in which the samples comprising the metal compound dissolved in water were decomposed. The transmitted monochromatic light was detected and the absorbance caused by copper atoms was measured. The absorbance and metal concentration were used to calculate sensitivity and detection limits for the studied metal. The sensitivity, limit of detection, and quantification for copper were 0.45 ± 0.02, 0.25 ± 0.01, and 0.85 ± 0.04 ppm, respectively. 相似文献
84.
Talyzin AV Anoshkin IV Krasheninnikov AV Nieminen RM Nasibulin AG Jiang H Kauppinen EI 《Nano letters》2011,11(10):4352-4356
A novel material, graphene nanoribbons encapsulated in single-walled carbon nanotubes (GNR@SWNT), was synthesized using confined polymerization and fusion of polycyclic aromatic hydrocarbon (PAH) molecules. Formation of the GNR is possible due to confinement effects provided by the one-dimensional space inside nanotubes, which helps to align coronene or perylene molecules edge to edge to achieve dimerization and oligomerization of the molecules into long nanoribbons. Almost 100% filling of SWNT with GNR is achieved while nanoribbon length is limited only by the length of the encapsulating nanotube. The PAH fusion reaction provides a very simple and easily scalable method to synthesize GNR@SWNT in macroscopic amounts. First-principle simulations indicate that encapsulation of the GNRs is energetically favorable and that the electronic structure of the encapsulated GNRs is the same as for the free-standing ones, pointing to possible applications of the GNR@SWNT structures in photonics and nanoelectronics. 相似文献
85.
A methodology is proposed for systematic map assessment to contribute to landscape-change research. Two major topic areas are dealt with, namely: content, quality and usefulness of landscape information on different maps; and methods used in the spatial conversion of maps into digital systems (e.g. geographical information systems). The major focus is on information about physical landscape characteristics (e.g. land cover) and land uses. The approach was tested using a sequence of nine large- and medium-scale basic maps of the island of Ruissalo in SW Finland from between 1690 and 1998. Fundamental differences were found in the thematic consistency of landscape information, mainly related to the scale, purpose and generalization of landscape information on different maps. Spatial matching was tested for a set of three old maps using four image rectification functions. The results showed that spatial matching of old maps is difficult, and success in rectification is influenced by many factors. Evaluation and selective transformation of landscape information from maps and the use of supportive information from other sources can assist in landscape-change analysis based on map sequences. 相似文献
86.
87.
Cellular access control and charging for mobile operator wireless local area networks 总被引:1,自引:0,他引:1
This article presents a system architecture, design considerations, and rationale for a mobile operator wireless LAN. The article also discusses the system implementation and performance issues. The system presented reuses GSM and GPRS mechanisms for user authentication, access control, subscriber management, operator roaming, and billing, while still being compatible with wireless Internet service provider networks and IETF and IEEE protocols such as RADIUS, EAP, and IEEE 802.1x. The architecture is a result of research carried out by Nokia between 1999 and 2002. The designed architecture has also been verified in a complete system implementation. 相似文献
88.
Temperature Coefficient of Microwave Resonance Frequency of a Low-Temperature Cofired Ceramic (LTCC) System 总被引:2,自引:1,他引:1
Heli Jantunen Antti Uusimäki Risto Rautioaho Seppo Leppävuori 《Journal of the American Ceramic Society》2002,85(3):697-699
A family of low-temperature cofired ceramics (LTCC) based on mixtures of a commercial dielectric, MgTiO3 –CaTiO3 (designated MMT-20) and ZnO, SiO2 , and B2 O3 , has been investigated for microwave applications. The main objective was to optimize the three key properties—relative permittivity (ɛr ), dissipation factor (DF), and the temperature dependence of the microwave resonance frequency (τf )—through adjustment of the composition. A further objective was to estimate the limits on compositional variability while maintaining acceptable properties. The developed microstructures, after firing at 900°C, were studied using X-ray diffractometry and scanning electron microscopy/energy dispersive spectrometry techniques and compared with the dielectric parameters. The optimum composition (wt%) was found to lie in the ranges 45.8–44.9, ZnO; 17.25–17.55, B2 O3 ; 6.95–7.05, SiO2 ; and 30–30.5, MMT-20, yielding values of ɛr = 8.5–9.5, DF < 0.93 × 10−3 ppm/K, and τf < ±10 ppm/K. 相似文献
89.
Caroline Darbos Ferran Albajar Tullio Bonicelli Giuseppe Carannante Mario Cavinato Fabio Cismondi Grigory Denisov Daniela Farina Mario Gagliardi Franco Gandini Thibault Gassmann Timothy Goodman Gregory Hanson Mark A. Henderson Ken Kajiwara Karen McElhaney Risto Nousiainen Yasuhisa Oda Toshimichi Omori Alexander Oustinov Darshankumar Parmar Vladimir L. Popov Dharmesh Purohit Shambhu Laxmikanth Rao David Rasmussen Vipal Rathod Dennis M. S. Ronden Gabriella Saibene Keishi Sakamoto Filippo Sartori Theo Scherer Narinder Pal Singh Dirk Strauß Koji Takahashi 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(1):4-20
90.
A methodology is proposed for systematic map assessment to contribute to landscape-change research. Two major topic areas are dealt with, namely: content, quality and usefulness of landscape information on different maps; and methods used in the spatial conversion of maps into digital systems (e.g. geographical information systems). The major focus is on information about physical landscape characteristics (e.g. land cover) and land uses. The approach was tested using a sequence of nine large- and medium-scale basic maps of the island of Ruissalo in SW Finland from between 1690 and 1998. Fundamental differences were found in the thematic consistency of landscape information, mainly related to the scale, purpose and generalization of landscape information on different maps. Spatial matching was tested for a set of three old maps using four image rectification functions. The results showed that spatial matching of old maps is difficult, and success in rectification is influenced by many factors. Evaluation and selective transformation of landscape information from maps and the use of supportive information from other sources can assist in landscape-change analysis based on map sequences. 相似文献