Quality of service management for IPTV services support in VANETs: a performance evaluation study

In order to deliver a qualitative Internet Protocol Television (IPTV) service over vehicular ad hoc networks (VANETs), a quality of service (QoS) mechanism is needed to manage the allocate of network resources to the diverse IPTV application traffic demands. Unlike other mobile network, VANETs have certain unique characteristic that presents several difficulties in providing an effective QoS. Similarly, IPTV requires a constant stream for QoS which at the moment is quite difficult due to the inherent VANET characteristics. To provide an effective QoS that will meet the IPTV application service demands, VANETs, must satisfy the compelling real-time traffic streaming QoS requirement (i.e., minimum bandwidth allocation, packet loss and jitter). In this report, we evaluate via simulation the feasibility of deploying quality IPTV services over VANETs, by characterizing the association between the IPTV streaming quality determining factors (i.e., throughput, delay, loss, jitter) and the IPTV quality degradation, with respect to node density and node velocity. Furthermore, we used an objective QoS metric (Media-Delivery-Index) to identify, locate and address the loss or out-of-order packet. We outline how, using these information’s can support in shaping network parameters to optimize service flows. The implementation assures a priority for handling IPTV traffic, such that maximise the usage of VANETs resources, and opens the possibility that loss and delay can be minimised to a degree that could guarantee quality IPTV service delivery among vehicle in a vehicular network system.

     

Benard convection in a non-linear magnetic fluid under the influence of a non-vertical magnetic field

This work examines the convective instability of a horizontal layer of magnetohydrodynamic fluid of variable permeability when subjected to a non-vertical magnetic field. We use a model proposed by P. H. Roberts [9] in the context of neutron stars but the results obtained are aso relevant to the area of ferromagnetic fluids. The presence of the variable permeability has no effect on the development of instabilities through the mechanism of stationary convection but influences the threshold of overstable convection which is often the preferred mechanism in non-terrestrial applications. In the context of ferromagnetic fluids, both stationary and overstable instability can be expected to be realisable possibilities.     

B(E2) value of even-even ~(108-112)Pd isotopes by interacting boson model-1

This work studies the systematic reduced transition probabilities B(E2)↓,intrinsic quadrupole moments and deformation parameters of Pd isotopes with even neutrons from N=62 to 66.The downward reduced transition probabilities B(E2)↓from gamma transition 8+to 6+,6+to 4+,4+to 2+and 2+to 0+states of even-even108 112Pd isotopes were calculated by the Interacting Boson Model(IBM-1)and compared with the available previous experimental results.The ratio of the excitation energies of the first 4+and the first 2+excited states,R4/2,is also studied for the classification of symmetry of these nuclei.Furthermore we have studied systematically the transition rate R=B(E2:L+→(L 2)+)/B(E2:2+→0+)of some of the low-lying quadrupole collective states in comparison with the available experimental data.The associated quadrupole moments and deformation parameters have been calculated.The results of this calculation are in good agreement with the corresponding available experimental data.The108 112Pd isotopes show the O(6)symmetry.     

Monolithic QW laser beam steering and wavelength tunability

We demonstrate a monolithic tunable laser on a QW structure by integrating an optical beam steering section with an area-selectively intermixed QW gain section. Wavelength switching is achieved by steering the laser beam over an optical gain medium that consists of two laterally adjacent quantum well regions selectively intermixed to varying extents. The device output had a total of 10 nm wavelength tuning that was controlled by injecting separate electrical current values to each of the steering contacts and the amplifier contact.     

Analyses for various doping structures of SOI-based optical phase modulator using free carrier dispersion effect

This paper highlights the study on various structure of silicon-on-insulator (SOI) optical phase modulators based on free carrier dispersion effect. The proposed modulators employ the forward biased P-I-N diode structure integrated in the waveguide and will be working at 1.55 μm optical telecommunications wavelength. Three kinds of structure are compared systematically where the p+ and n+ doping positions are varied. The modeling and characterization of the SOI phase modulators was carried out by 3D numerical simulation package. Our results show that the position of doping regions have a great influences to the device performance. It was discovered that the best structure in this work demonstrated modulation efficiency of 0.015 V cm with a length of 155 μm.     

Measurements of Young’s and shear moduli of rail steel at elevated temperatures

The design and modelling of the buckling effect of Continuous Welded Rail (CWR) requires accurate material constants, especially at elevated temperatures. However, such material constants have rarely been found in literature. In this article, the Young’s moduli and shear moduli of rail steel at elevated temperatures are determined by a new sonic resonance method developed in our group. A network analyser is used to excite a sample hanged inside a furnace through a simple tweeter type speaker. The vibration signal is picked up by a Polytec OFV-5000 Laser Vibrometer and then transferred back to the network analyser. Resonance frequencies in both the flexural and torsional modes are measured, and the Young’s moduli and shear moduli are determined through the measured resonant frequencies. To validate the measured elastic constants, the measurements have been repeated by using the classic sonic resonance method. The comparisons of obtained moduli from the two methods show an excellent consistency of the results. In addition, the material elastic constants measured are validated by an ultrasound test based on a pulse-echo method and compared with previous published results at room temperature. The measured material data provides an invaluable reference for the design of CWR to avoid detrimental buckling failure.     

A comprehensive study of optimization algorithm for wireless coverage in indoor area

Coverage optimization using minimum number of transmitters is critical to service providers and vendors that need to control the coverage as well as the huge costs involved. In this regards, an existing coverage algorithm for determining the minimum number of transmitting antennas as well as their appropriate locations to provide the optimized wireless coverage for indoor environment is studied in this paper. The algorithm uses ray-tracing to predict the signal distribution from the transmitter to the sampling points (receivers) and genetic algorithm to determine the minimum number of transmitters and their corresponding locations to achieve the optimum wireless coverage. The complexity and performance of the algorithm are also analyzed and it is found that it has exponentially increasing complexity of $2^{n}$ and the change of computation time is greater with small change of the number of receiving points. Moreover, under the multi-transmitter scenario (real case), the accuracy achieved by fading, coverage ability, and signal to noise ratio is in the range of 96–99 %.     

B（E2） value of even-even ^108-112Pd isotopes by interacting boson model-1

This work studies the systematic reduced transition probabilities B（E2）↓, intrinsic quadrupole moments and deformation parameters of Pd isotopes with even neutrons from N =62 to 66. The downward reduced transition probabilities B（E2）↓from gamma transition 8^＋to 6^＋, 6^＋ to 4^＋, 4^＋ to 2^＋ and 2^＋ to 0＋states of even-even108 112Pd isotopes were calculated by the Interacting Boson Model（IBM-1） and compared with the available previous experimental results. The ratio of the excitation energies of the first 4＋and the first 2＋excited states, R4/2, is also studied for the classification of symmetry of these nuclei. Furthermore we have studied systematically the transition rate R = B（E2： L＋ →（L 2）＋）/B（E2 ： 2＋ →0＋） of some of the low-lying quadrupole collective states in comparison with the available experimental data. The associated quadrupole moments and deformation parameters have been calculated. The results of this calculation are in good agreement with the corresponding available experimental data. The108 112Pd isotopes show the O（6） symmetry.     

Effects of polarization force and nonthermal ions on dust-acoustic (DA) shock waves in a strongly coupled dusty plasma with positively charged dust

The nonlinear propagation of the dust-acoustic (DA) waves in a strongly coupled dusty plasma containing Maxwellian electrons, nonthermal ions, and positively charged dust is theoritically investigated by a Burgers equation. The effects of the polarization force (which arises due to the interaction between electrons and highly positively charged dust grains) and nonthermal ions are studied. DA shock waves are found to exist with positive potential only. It represents that the strong correlation among the charged dust grains is a source of dissipation, and is responsible for the formation of DA shock waves. The effects of polarization force and nonthermal ions significantly modified the basic features of DA shock waves in strongly coupled dusty plasma.