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71.
Saied M. Abd El-atty Dimitrios N. Skoutas Angelos N. Rouskas George T. Karetsos 《Wireless Personal Communications》2008,46(1):33-45
In future wireless networks multimedia applications are expected to finally dominate the overall traffic volume. Shared channels
are more suitable for the transmission of this type of traffic, as they are able to periodically adjust their transmission
rate. In this paper, we introduce a cross-layer framework for WCDMA based networks which aims to make the packet scheduling
procedure more efficient. In addition to that, we further propose a traffic scheduling scheme which serves the connections
not only according to their delay sensitivity, but also according to the predicted state of their wireless channel. The efficiency
of the proposed scheme, in terms of average packet delay and channel utilization is verified via simulations. 相似文献
72.
This work describes the construction of a simple optical sensor for the rapid, selective and sensitive detection of urea in milk using air stable lipid films with incorporated urease. The lipid film is stabilized on a glass filter by polymerization using UV (ultra-violet) radiation prior its use. Methacrylic acid was the functional monomer, ethylene glycol dimethacrylate was the crosslinker and 2,2′-azobis-(2-methylpropionitrile) was the initiator. Urease is incorporated within this mixture prior to the polymerization. The presence of the enzyme in these films quenched this fluorescence and the colour became similar to that of the filters without the lipid films. A drop of aqueous solution of urea provided a “switching on” of the fluorescence which allows the rapid detection of this compound at the levels of 10−8 M concentrations. The investigation of the effect of potent interferences included a wide range of compounds usually found in foods and also of proteins and lipids. These lipid membranes were used for the rapid detection of urea in milk. 相似文献
73.
Mohamed Khairy Dimitrios K. Kampouris Rashid O. Kadara Craig E. Banks 《Electroanalysis》2010,22(21):2496-2501
Gold ensembles for the trace level sensing of arsenic(III) in the presence of copper(II) are reported. The gold ensembles are fabricated using citrate capped gold nanoparticles which are chemically synthesised in an aqueous solution with an aliquot of this simply cast onto an economical and disposable screen printed electrode. After drying at room temperature, the gold ensembles are ready for use. The gold ensembles are explored towards the sensing of arsenic(III) in the presence of copper(II) using anodic stripping voltammetry where the corresponding stripping peaks are well resolved and using this protocol it is possible to readily detect 3 µg L?1 (3 ppb) with a detection limit of 0.4 µg L?1 (0.4 ppb). Proof‐of‐concept is also shown for the sensing of arsenic(III) in a canal water sample. Given the low cost of the sensor and ease of fabrication, the gold ensembles hold promise for the sensing of arsenic(III) in water samples where copper(II) may be present. 相似文献
74.
In this paper, we address various aspects of packet data transmission in terrestrial trunked radio (TETRA) networks giving
particular emphasis on the performance of applications transmitting small messages between a number of radio terminals and
a fixed server. The utilization of such applications is constantly increasing in public safety networks and so does the need
to dimension and configure TETRA networks to meet their reliability, delay and loss requirements. We present simulation results
for a variety of practical scenarios such as loading the packet data channel (PDCH) with different mobile station (MS) populations
engaged in transmitting packet data (PD) at various rates. We quantify key performance indicators of the PDCH such as packet
delay and packet loss rate. Furthermore, we provide an in-depth analysis of the impact of non-PD MS population—i.e., the loading
of main control channel (MCCH)—on the average packet delay. Our results provide an insight of how network loading parameters
interact with the protocol performance and may help in dimensioning and planning TETRA networks, and in particular, in determining
the number of PD terminals that can be supported in a cell for a given traffic profile and QoS requirements. 相似文献
75.
Denys Dutykh Theodoros Katsaounis Dimitrios Mitsotakis 《Journal of computational physics》2011,230(8):3035-3061
Finite volume schemes are commonly used to construct approximate solutions to conservation laws. In this study we extend the framework of the finite volume methods to dispersive water wave models, in particular to Boussinesq type systems. We focus mainly on the application of the method to bidirectional nonlinear, dispersive wave propagation in one space dimension. Special emphasis is given to important nonlinear phenomena such as solitary waves interactions, dispersive shock wave formation and the runup of breaking and non-breaking long waves. 相似文献
76.
Temporal cleaning of a high-energy fiber-based ultrafast laser using cross-polarized wave generation
Zaouter Y Ramirez LP Papadopoulos DN Hönninger C Hanna M Druon F Mottay E Georges P 《Optics letters》2011,36(10):1830-1832
We report the use of cross-polarized wave generation to perform both pulse shortening and temporal cleaning of a high-energy ytterbium-doped fiber-based femtosecond laser system. The nonlinear processes allow both a highly efficient nonlinear conversion of 20% and a large compression ratio of 3.5, with inherently improved coherent and incoherent contrasts. This results in the generation of 37 μJ, 115 fs pulses at a repetition rate of 100 kHz with high temporal quality. 相似文献
77.
78.
Isothermal calorimetry approach to evaluate shelf life of foods 总被引:7,自引:0,他引:7
79.
Dimitrios Priftis Georgios Sakellariou Jimmy W. Mays Nikos Hadjichristidis 《Journal of polymer science. Part A, Polymer chemistry》2010,48(5):1104-1112
Diels–Alder cycloaddition reactions were used to functionalize multiwalled carbon nanotubes (MWNTs) with 1‐benzocylcobutene‐1′‐phenylethylene (BCB‐PE) or 4‐hydroxyethylbenzocyclobutene (BCB‐EO). The covalent functionalization of the nanotubes with these initiator precursors was verified by FTIR and thermogravimetric analysis (TGA). After appropriate transformations/additions, the functionalized MWNTs were used for surface initiated anionic and ring opening polymerizations of ethylene oxide and ε‐caprolactone (ε‐CL), respectively. The OH‐end groups were transformed to isopropylbromide groups by reaction with 2‐bromoisobutyryl bromide, for subsequent atom transfer radical polymerization of styrene or 2‐dimethylaminoethyl methacrylate to afford the final diblock copolymers. 1H NMR, differential scanning calorimetry (DSC), TGA, and transmission electron microscopy (TEM) were used for the characterization of the nanocomposite materials. TEM images showed the presence of a polymer layer around the MWNTs as well as the dissociation of MWNT bundles. Consequently, this general methodology, employing combinations of different polymerization techniques, increases the diversity of diblocks that can be grafted from MWNTs. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1104–1112, 2010 相似文献
80.