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41.
Most mobile radio networks have been planned based on the classical cellular concept. However, alternative planning strategies
that lead to more efficient network configurations are necessary due to the fact that the traffic density is generally far
from constant throughout the service area, making necessary the relocation of base stations inside the traffic hotspots. If
the traffic is characterized in a discrete way, the optimization of base stations location resembles vector quantization,
a well-known problem in signal processing. In this paper, we use this analogy to propose a mobile radio network planning algorithm.
Simulation results show that higher trunking efficiency as well as improved frequency assignment can be obtained if an existing
mobile radio network is redesigned using the presented strategy.
Raúl Chávez-Santiago was born in Oaxaca City, Mexico. He obtained the B.Sc. degree in communications and electronics engineering in 1997 from
the School of Mechanical and Electrical Engineering (ESIME-IPN), and the M.Sc. degree in electrical engineering in 2001 from
the Center of Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV-IPN) in Mexico City.
He has professional experience as Computer Networking Engineer, and Research and Teaching Assistant. Currently, he is completing
his studies toward the Ph.D. degree at Ben-Gurion University (BGU) of the Negev, Israel. In 2002, he received the URSI Young
Scientist Award. His main research interests are the optimal planning of radio communication networks, the electromagnetic
compatibility of terrestrial and satellite radio systems, and the efficient use of the radio spectrum. He is an IEEE and IEICE
student member, and a URSI radio scientist.
Avi Raymond was born in Yavne, Israel. He received the B.Sc. and M.Sc. degrees in electrical engineering from Ben-Gurion University (BGU)
of the Negev in 2000 and 2005, respectively.
He worked for two years in a communication company in the field of Telephony and Broadband Services. He also worked as a Research
Assistant in the communications laboratory at BGU. He currently works at Elta Electronic Industries Ltd. as System Engineer
and pursues studies toward a second M.Sc. degree in systems engineering at the Technion Institute of Technology, Haifa, Israel.
His research interests are the optimization algorithms for frequency assignment in cellular networks.
Vladimir Lyandres was born in 1944, in Vologda, Russia. He received the M.Sc. degree in communications engineering in 1966 and the Ph.D. degree
in communications theory in 1972 from the State University of Telecommunications (SUT), Saint Petersburg, Russia. He was with
SUT until 1990 holding a position of Senior Scientific Associate and working on research and development of digital transmission
systems, modeling of radio communication channels and algorithms of frequency planning for broadcasting and cellular systems.
Since 1991 he holds a position of Researcher at the communications laboratory and Professor at the Department of Electrical
and Computer Engineering, Ben-Gurion University (BGU) of the Negev, Israel. His research interests include synthesis of Markov
models, combinatorial optimization, and adaptive power loading. He is a senior member of IEEE and member of IEICE. 相似文献
42.
Manohar Chaudhari Pavlina Koleva Vladimir Poulkov Oleg Asenov 《Wireless Personal Communications》2017,97(2):1729-1752
In this paper a new power efficient routing algorithm for MANETs with self-organizing and self-routing features is described and its performance analyzed in different simulation scenarios. The algorithm has the logic of a non-cooperative routing algorithm based on the evaluation of a weight parameter, the latter being a function of properties of the MANET nodes related to the nominal available power and the transmission range. A self-estimation of this weight parameter for each node is introduced in the routing process based on the status and functional history of the node. The routing is based on network layering, formation of service areas in each layer and choice of nodes from these areas to have the functionality of default gateways. The proposed algorithm, named service zone gateway prediction (SZGP), is a hybrid type of routing mechanism, incorporating pre-computed multipath hop-by-hop distributed routing, with a periodically updated hierarchical multilayered structure. The results from the simulation experiments show that the performance of the proposed SZGP algorithm in relation to the basic performance parameters such as packet delivery ratio, delay and throughput are similar to those of the well-known AODV algorithm, but in relation to power efficiency the proposed algorithm outperforms AODV significantly. This is due to the fact that such an approach reduces the overall number of broadcasts in the network and ensures a reliable and energy efficient connection by balancing the load among the nodes. 相似文献
43.
Bostanov V 《IEEE transactions on bio-medical engineering》2004,51(6):1057-1061
The t-CWT, a novel method for feature extraction from biological signals, is introduced. It is based on the continuous wavelet transform (CWT) and Student's t-statistic. Applied to event-related brain potential (ERP) data in brain-computer interface (BCI) paradigms, the method provides fully automated detection and quantification of the ERP components that best discriminate between two samples of EEG signals and are, therefore, particularly suitable for classification of single-trial ERPs. A simple and fast CWT computation algorithm is proposed for the transformation of large data sets and single trials. The method was validated in the BCI Competition 2003, where it was a winner (provided best classification) on two data sets acquired in two different BCI paradigms, P300 speller and slow cortical potential (SCP) self-regulation. These results are presented here. 相似文献
44.
Dejan Reljic Vladimir Katic Veran Vasic 《电力电子》2005,3(2):59-62,75
因为人们越来越多地使用非线性负载,电网中就存在电源质量问题。在交流传动系统中广泛使用功率变换器,由于其非线性的工作运行状态,导致电压发生畸变,从而影响敏感设备的性能。本文试图分析由功率变换器供电的电梯交流传动系统对电源质量的影响。敏感电气设备和电梯交流传动系统都连接到0.4kV输电线路上。因功率逆变器导致的电压畸变能够导致系统故障甚至电气设备中部分元件的损坏。 相似文献
45.
Maxim L. Kulygin Gregory G. Denisov Vladimir V. Kocharovsky 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(1):31-40
Problems of high-power microwaves penetrating into and reflecting from a semiconductor (silicon) plate with non-stationary
processes are investigated. The plate is the basis of switches activated by laser-driven photoconductivity which changes its
properties when heated by the switched microwave power. Analytical criteria for the stationary solutions of the activated
(quasi-metallic) and deactivated (dielectric) states of the switch under the conditions of high-power microwave heating and
external cooling are found. Results of numerical simulations are also given for the problems of the switch activation by microwave
heating initiated by pulsed laser radiation, which increases the carrier density rapidly. Numerical simulations are carried
out using the finite-difference time-domain method with the unsplit perfectly matched layer absorbing boundary conditions.
We demonstrate various types of solutions depending on the basic parameters of the problems - microwave field intensity, laser
pulse energy and semiconductor doping. 相似文献
46.
Venema B Blanik N Blazek V Gehring H Opp A Leonhardt S 《IEEE transactions on bio-medical engineering》2012,59(7):2003-2010
Pulse oximetry is a well-established, noninvasive photoplethysmographic method to monitor vital signs. It allows us to measure cardiovascular parameters, such as heart rate and arterial oxygen saturation, and is considered an essential monitoring tool in clinical routine. However, since many of the conventional systems work in transmission mode, they can only be applied to the thinner or peripheral parts of the body, such as a finger tip. This has the major disadvantage that, in case of shock-induced centralization and a resulting drop in perfusion, such systems cannot ensure valid measurements. Therefore, we developed a reflective in-ear sensor system that can be worn in the ear channel like a headphone. Because the sensor is integrated in an ear mold and positioned very close to the trunk, reliable measurement is expected even in case of centralization. An additional advantage is that the sensor is comfortable to wear and has considerable resistance to motion artifacts. In this paper, we report on hypoxia studies with ten healthy participants which were performed to analyze the system with regard to the detection of heart rate and arterial oxygen saturation. It was shown earlier that, due to the high signal quality, heart rate can easily be detected. Using the conventional calculation principle, based on Beer-Lambert's law combined with a single-point calibration method, we now demonstrate that the detection of arterial oxygen saturation in the human ear canal is possible using reflective saturation sensors. 相似文献
47.
Evidence for biotic control of Australian reservoir phytoplankton communities and the potential for applied biomanipulation 总被引:1,自引:0,他引:1
Vladimir Matveev 《Lakes & Reservoirs: Research and Management》1998,3(2):105-111
Although some concerns have been expressed with respect to the applicability of biomanipulation to Australian reservoirs and other inland waters, no major obstacles were found in this review. The previous doubts stimulated research, which has provided evidence for unexpected mechanisms of food web interactions, such as positive effects of small copepods on planktonic algae, higher than usual grazing potential of cladoceran communities, and direct positive effects of planktivores on phytoplankton. Further research into zooplankton-cyanobacteria interactions should indicate how widespread is the previously reported ability of some southern hemisphere crustaceans to benefit at a population level from feeding on cyanobacteria. Quantitative fisheries acoustics, which has not been widely used in biomanipulation trials before, is a promising new tool in the assessment of the biomass of planktivorous fish in the pelagic zone of reservoirs. 相似文献
48.
Ggoch Ddeul Han William R. Collins Trisha L. Andrew Vladimir Bulović Timothy M. Swager 《Advanced functional materials》2013,23(24):3061-3069
New tetraalkylcyclobutadiene–C60 adducts are developed via Diels–Alder cycloaddition of C60 with in situ generated cyclobutadienes. The cofacial π‐orbital interactions between the fullerene orbitals and the cyclobutene are shown to decrease the electron affinity and thereby increase the lowest unoccupied molecular orbital (LUMO) energy level of C60 significantly (ca. 100 and 300 meV for mono‐ and bisadducts, respectively). These variations in LUMO levels of fullerene can be used to generate higher open‐circuit voltages (VOC) in bulk heterojunction polymer solar cells. The tetramethylcyclobutadiene–C60 monoadduct displays an open‐circuit voltage (0.61 V) and a power conversion efficiency (2.49%) comparable to the widely used P3HT/PCBM (poly(3‐hexylthiophene/([6,6]‐phenyl‐C61‐butyric acid methyl ester) composite (0.58 V and 2.57%, respectively). The role of the cofacial π‐orbital interactions between C60 and the attached cyclobutene group was probed chemically by epoxidation of the cyclobutene moiety and theoretically through density functional theory calculations. The electrochemical, photophysical, and thermal properties of the newly synthesized fullerene derivatives support the proposed effect of functionalization on electron affinities and photovoltaic performance. 相似文献
49.
Vladimir Svrcek Katerina Dohnalova Davide Mariotti Minh Tuan Trinh Rens Limpens Somak Mitra Tom Gregorkiewicz Koiji Matsubara Michio Kondo 《Advanced functional materials》2013,23(48):6051-6058
Substantial improvements of the absolute photoluminescence quantum yield (QY) for surfactant‐free silicon nanocrystals (Si‐ncs) by atmospheric pressure microplasma 3‐dimensional surface engineering are reported. The effect of surface characteristics on carrier multiplication mechanisms is explored using transient induced absorption and photoluminescence QY. Surface engineering of Si‐ncs is demonstrated to lead to more than 120 times increase in the absolute QY (from 0.1% up to 12%) within an important spectral range of the solar emission (2.3–3 eV). The Si‐ncs QY is shown to be stable when Si‐ncs are stored in ethanol at ambient conditions for three months. 相似文献
50.
Srinivasa R Raghavan Vladimir Ladik Klemens B Meyer 《IEEE transactions on information technology in biomedicine》2005,9(2):229-238
The complexity, variability, quantitative nature, and data density of treatment for chronic kidney failure make dialysis information systems excellent candidates for computerized decision support. We describe the development of an intelligent system building on existing knowledge and susceptible to reconfiguration on the basis of knowledge acquired during the use of the system. Various decision support techniques were used to design and develop the decision support modules. This paper briefly reviews the literature on clinical decision support, discusses some of the problems faced by practitioners in managing chronic kidney failure (end-stage renal disease) patients, and sets forth the decision support techniques used in developing a dialysis decision support system. 相似文献