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International Conference on Cognitive Radio Oriented Wireless Networks and Communications

作者： Khalid A. Qaraqe Zied Bouida Mohamed Abdallah Mohamed-Slim Alouini Department of Electrical and Computer Engineering Texas A&M University at Qatar Doha Qatar Electrical Engineering Program KAUST Mekkah Province Saudi Arabia

Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to minimize the average number of switched branches at the secondary transmitter while increasing the capacity of the secondary link. The proposed switching efficient scheme (SES) uses the scan and wait (SWC) combining technique where a transmission occurs only when a branch with an acceptable performance is found, otherwise data is buffered. In our scheme, the modulation constellation size and the used transmit branch are determined to achieve the highest spectral efficiency with a minimum processing power, given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. Selected numerical examples show that the SES scheme minimizes the average number of switched branches for the average and the high secondary signal-to-noise ratio range. This improvement comes at the expense of a small delay introduced by the SWC technique. For reference, we also compare the performance of the SES scheme to the selection diversity scheme (SDS) where the best branch verifying the modulation mode and the interference constraint is always selected.

关键词： Switches Modulation Signal to noise ratio Diversity reception Interference constraints Fading Bit error rate

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Spectrally Efficient Switched Transmit Diversity for Spectrum Sharing Systems

Spectrally Efficient Switched Transmit Diversity for Spectru...

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IEEE Conference on Vehicular Technology (VTC)

作者： Zied Bouida Mohamed Abdallah Khalid A. Qaraqe Mohamed-Slim Alouini Department of Electrical and Computer Engineering Texas A&M University Qatar Doha Qatar Electrical Engineering Program KAUST Thuwal Mekkah Saudi Arabia

Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to increase the spectral efficiency of the secondary link. The proposed bandwidth efficient scheme (BES) uses the scan and wait (SWC) combining technique where a transmission occurs only when a branch with an acceptable performance is found, otherwise data is buffered. In our scheme, the modulation constellation size and the used transmit branch are determined to achieve the highest spectral efficiency given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. Selected numerical examples show that the BES scheme increases the capacity of the secondary link when compared to an existing switching efficient scheme (SES). This spectral efficiency comes at the expense of an increased average number of switched branches and thus an increased average delay.

关键词： Switches Modulation Signal to noise ratio Interference constraints Diversity reception Fading Delay

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Minimum time control of helicopter UAVs using computational dynamic optimization

Minimum time control of helicopter UAVs using computational ...

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9th IEEE International Conference on Control and Automation, ICCA 2011

作者： Tang, K. Wang, B. Kang, W. Chen, B. Internship Program Naval Postgraduate School Monterey CA 93943 United States Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore Department of Applied Mathematics Naval Postgraduate School Monterey CA 93943 United States

ISBN: (纸本)9781457714757

This paper focuses on the problem of minimum time trajectory planning for helicopter UAVs. It is formulated as a nonlinear optimal control subject to the dynamics and limitations of helicopter UAVs. The dynamical system is defined by a set of fifteen states nonlinear differential equations developed for HeLion, a UAV helicopter constructed in National University of Singapore (NUS). The problem is then solved numerically using pseudospectral method for dynamic optimization. The results show that minimum time trajectories are highly nonlinear that require complicated maneuvering. © 2011 IEEE.

关键词： Nonlinear equations

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Photoactivity tests of TiO2 and ZnO sunscreen ingredients

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MRS Online Proceedings Library 2011年第1期1413卷 1-6页

作者： Lewicka, Zuzanna. A. Colvin, Vicki. L. Applied Physics Program Department of Electrical and Computer Engineering Rice University Houston USA Department of Chemistry Rice University Rice University Houston USA

Nanosized titanium dioxide (TiO2) and zinc oxide (ZnO) are widely used as inorganic sunscreen pigments. However, these metal oxide particles may also be photocatalytic and generate DNA-damaging reactive oxygen species. Therefore, we evaluated the photochemical properties of the whole sunscreen emulsions that contained nanoscale components and the inorganic particles derived from these sunscreens using several assays such as dichlorofluorescein fluorescence, the decolorization of Congo red dye and DMPO spin trap electron paramagnetic resonant spectroscopy. The results of these three tests showed that samples with ZnO nanoscale materials were more photoactive than the samples that contained TiO2 nanoparticles.

关键词： photochemical nanostructure nanoscale

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Handling failures of static sensor nodes in wireless sensor network by use of mobile sensors

Handling failures of static sensor nodes in wireless sensor ...

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25th IEEE International Conference on Advanced Information Networking and Applications Workshops, WAINA 2011

作者： Pignaton De Freitas, Edison Heimfarth, Tales Netto, Ivayr Farah Pereira, Carlos Eduardo Ferreira, Armando Morado Wagner, Flávio Rech Larsson, Tony IDE Halmstad University Halmstad Sweden Institute of Informatics Federal University of Rio Grande Do Sul Porto Alegre Brazil Computer Science Department Federal University of Lavras Lavras Brazil Electrical Engineering Department Federal University of Rio Grande Do Sul Porto Alegre Brazil Defense Engineering Graduate Program Military Institute of Engineering Rio de Janeiro Brazil

ISBN: (纸本)9780769543383

Node failures in Wireless Sensor Networks composed by static sensor nodes are common due to the nature of the sensor devices and the usually harsh environments in which they are deployed. Node failures can diminish the performance of the network as a whole, thus affecting its functionality in delivering the desired services. For instance, significant regions can become uncovered due to failure of several nearby nodes. This paper reports a study about the use of mobile sensor nodes acting in cooperation with static ones in order to fill gaps created by faulty static nodes. The proposed fault handling mechanism presents alternative policies with pros and cons, depending on the user priorities imposed to the system and the occurrence of failures. A discussion about this topic is presented based on results obtained by simulation of the proposed mechanisms. © 2011 IEEE.

关键词： Sensor nodes

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Automatic Generation of Balletic Motions

Automatic Generation of Balletic Motions

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IEEE/ACM International Conference on Cyber-Physical Systems (ICCPS)

作者： Amy LaViers Magnus Egerstedt Yushan Chen Calin Belta School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA Department of Electrical and Computer Engineering Boston University Boston MA USA Department of Mechanical Engineering Division of Systems Engineering and the Bioinformatics Graduate Program Boston University MA USA

As cyber-physical systems become more prevalent, specifications for these systems must be formulated in a more nuanced manner. This paper presents a particular instantiation of such specification by proposing a framework that endows robotic motions with a sense of aesthetic style. Drawing inspiration from classical ballet, poses are cast as discrete states and movements as the transitions between these states. Thus, a given movement style is encoded in the availability of transitions at each state, and the dynamics of a complex physical trajectory are abstracted as a system which moves between these states. Using Linear Temporal Logic (LTL), we are able to further constrain the set of possible sequences through the transition system and thus prevent it from evolving through a sequence of states that is physically impossible or aesthetically undesirable. Our overarching objective is to facilitate subtle degrees of control over systems as such subtleties are required, more and more, to interact in a social and aesthetically driven world.

关键词： Automata Leg Legged locomotion Humans Trajectory Hip

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Parameter Estimation of Biological Phenomena Modeled by S-systems: An Extended Kalman Filter Approach

Parameter Estimation of Biological Phenomena Modeled by S-sy...

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IEEE Conference on Decision and Control

作者： N. Meskin H. Nounou M. Nounou A. Datta E. R. Dougherty Electrical Engineering Department Qatar University Doha Qatar Electrical and Computer Engineering Program Texas A&M University at Qatar Doha Qatar Chemical Engineering Program Texas A&M University at Qatar Doha Qatar Department of Electrical and Computer Engineering Texas A&M University College Station TX 77843 USA Department of Electrical and Computer Engineering Texas A&M University College Station TX 77843 USA

ISBN: (纸本)9781612848006

Recent advances in high-throughput technologies for biological data acquisition have spurred a broad interest in the development of mathematical models for biological phenomena. S-systems, which offer a good compromise between accuracy and mathematical flexibility, are a promising framework for modeling the dynamical behavior of genetic regulatory networks (GRNs), as well as that of biochemical pathways. In the S-system modeling framework, the number of unknown parameters is much more than the number of metabolites and this makes the parameter estimation task a challenging one. In this paper, a new parameter estimation algorithm is developed based on the Extended Kalman filter (EKF) approach. It is first shown that the conventional EKF approach is not capable of estimating the unknown parameters of S-systems. To remedy this problem, a new iterative extended Kalman Filtering algorithm is developed in which the EKF algorithm is applied iteratively to the available noisy time profiles of the metabolites. The proposed estimation algorithm is applied to a generic branched pathway and the Cad system of ***. The simulation results demonstrate the effectiveness of the proposed scheme.

关键词： Parameter estimation Unknown parameter Biological Phenomena Extended Kalman filters Biochemical Pathway metabolites

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Theoretical and Experimental Study of Barium Zinc-Cadmium Tantalate-based Microwave Dielectrics

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MRS Online Proceedings Library (OPL) 2011年第1期783卷 B4.7-B4.7页

作者： Shaojun Liu Mark Van Schilfgaarde Jian Sun Louisa Badd David Smith Novak S. Petrovixc R. Taylor N. Newman Chemical and Materials Engineering Department Science and Engineering of Materials Program Center for Solid State Science Arizona State University Tempe AZ 85287–6006 Electrical and Computer Engineering Department Queens land University Paddington Australia 4064

Single-phase Ba(Cd1/3Ta2/3)O3 ceramics have been produced using conventional powder processing methods. In our initial investigations, 2wt% ZnO powder was added to act as a sintering aid since a high-density ceramic was not formed from solid-state diffusion alone. The resulting Ba(Cd0.327Zn0.006Ta2/3)O3 material sintered at 1550° C exhibits a dielectric constant of ∼33 and loss tangent of <5×10−5 at 2 GHz. In our more recent work, we have used boron as a sintering aid to facilitate sintering at temperatures as low as 1300° C, enhance the structural quality and improve the microwave properties of Ba(Cd1/3Ta2/3)O3 dielectrics. TEM results indicate that the liquid sintering mechanism is an important factor for boron concentrations exceeding 0.5wt%, while a point defect mechanism plays the dominant role at lower boron concentrations. The presence of superstructure peaks and splitting of the (220) and (214) peaks in X-ray diffraction spectra are direct evidence for the distortion from cubic symmetry as a result of Cd and Ta ordering on the ***-initio electronic structure calculations within the local density functional approximation have been used to give insight into the unusual properties of this class of materials. In both Ba(Zn1/3Ta2/3)O3 and Ba(Cd/3Ta2/3)O3, the conduction band maximum and valence band minimum are composed of mostly weakly itinerant Ta 5d-and Zn-3d/Cd-4d levels, respectively. The covalent nature of the directional d-electron bonding in these high-Z oxides plays an important role in producing a more rigid lattice with higher melting points and enhanced phonon energies, and possibly inherently lower intrinsic microwave loss than comparable ionic materials.

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Temporal dietary patterns using kernel k-means clustering

Temporal dietary patterns using kernel k-means clustering

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13th IEEE International Symposium on Multimedia, ISM 2011

作者： Khanna, Nitin Eicher-Miller, Heather A. Boushey, Carol J. Gelfand, Saul B. Delp, Edward J. School of Electrical and Computer Engineering Purdue University West Lafayette IN United States Department of Nutrition Science Purdue University West Lafayette IN United States Epidemiology Program University of Hawaii Cancer Center Honolulu HI United States

ISBN: (纸本)9780769545899

Chronic diseases, such as heart disease, diabetes, and obesity, have been linked with diet. Nutrient intake is also associated with diet. However, much of the research completed to elucidate these associations has not incorporated the concept of time. This paper introduces the concept of temporal dietary patterns and demonstrates a novel construct of 24-hour temporal dietary patterns for energy intake, present in a sample of the adult U.S. population 20 years and older (NHANES 1999-2004 dataset). An appropriate distance metric is proposed for comparing 24-hour diet records and is used with kernel k-means clustering to identify the temporal dietary patterns. © 2011 IEEE.

关键词： Diseases

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GaN-Based Neutron Scintillators with a 6 LiF Conversion Layer

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MRS Online Proceedings Library 2011年第1期1396卷 130-133页

作者： Andrew G. Melton Eric Burgett Nolan Hertel Ian T. Ferguson Department of Electrical and Computer Engineering University of North Carolina at Charlotte Charlotte USA Nuclear Engineering Program Idaho State University Pocatello USA Nuclear Engineering and Radiological Engineering Program George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta USA

Thin film gallium nitride (GaN) scintillators have been produced by MOCVD and made neutron-sensitive by applying an enriched lithium-6 fluoride (6LiF) conversion layer. The 6Li(n,α) reaction produces both alpha and triton particles, which have very penetration depths in GaN. The range and energy deposition characteristics of these particles in GaN have been simulated. Alpha-induced scintillation was measured in silicon-doped GaN using an americium-241 (241Am) source. The thermal neutron responses of the 6LiF-coated GaN scintillator were tested using two thermal neutron sources, an 241Am-Be source inside a graphite pile and a reactor source. The scintillator was found to have a linear response to thermal neutron flux level over a range of more than three orders of magnitude.

关键词： Ga neutron irradiation nitride

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