Fast handover solution for network-based distributed mobility management in intelligent transportation systems

The current IP mobility protocols are called centralized mobility management (CMM) solutions, in which all data traffic and management signaling messages must be forwarded to an anchor entity. In some vehicle scenarios, vehicles may move as a group from one roadside unit to another (i.e., after traffic lights or traffic jams). This causes data traffic and exchanged mobility messages to peak at the anchor entity and, consequently, affects the network performance. A new design paradigm aimed at addressing the anchor entity issue is called distributed mobility management (DMM); it is an IETF proposal that is still being actively discussed by the IETF DMM working group. Nevertheless, network-based DMM is designed based on the well-known network-based CMM protocol Proxy Mobile IPv6 (PMIPv6). There is no significant difference between network-based DMM and PMIPv6 in terms of handover latency and packet loss. Because vehicles change their roadside unit frequently in this context, the IP addresses of mobile users (MUs) require fast IP handover management to configure a new IP address without disrupting ongoing sessions. Thus, this paper proposes the Fast handover for network-based DMM (FDMM) based on the Fast Handover for PMIPv6 (PFMIPv6). Several modifications to PFMIPv6 are required to adapt this protocol to DMM. This paper specifies the necessary extensions to support the scenario in which an MU has old IP flows and hence has multiple anchor entities. In addition, the analytic expressions required to evaluate and compare the handover performance of the proposed FDMM and the IETF network-based DMM have been derived. The numerical results show that FDMM outperforms the IETF network-based DMM in terms of handover latency, session recovery and packet loss at the cost of some extra signaling.     

A novel fair random access scheme with throughput optimization using fuzzy controller for wireless systems

Good backoff algorithms should be able to achieve high channel throughput while maintaining fairness among active nodes. In this paper, we propose a novel backoff algorithm to improve the fairness of random access channels, while maximizing channel throughput. The mechanism of the proposed backoff algorithm uses backoff delay (retransmission delay) and channel‐offered traffic to dynamically control the backoff interval, so that each active node increases its backoff interval in the case of collision by a factor which exponentially decreases as the backoff delay increases, and decreases its backoff interval in the case of successful transmission by a factor which exponentially decreases as the backoff delay of previous retransmission attempts increases. Also, the backoff interval is controlled according to the channel offered, traffic using a fuzzy controller to maximize channel throughput. Furthermore, the operation of the proposed backoff algorithm does not depend on knowledge of the number of active nodes. A computer simulation is developed using MATLAB to evaluate the performance of the proposed backoff algorithm and compare it with the binary exponential backoff (BEB) scheme, which is widely used owing to its high channel throughput, while its fairness is relatively poor. It is shown that the proposed backoff algorithm significantly outperforms the BEB scheme in terms of improving the performance of fairness, and converges to the ideal performance as the minimum backoff interval increases, while achieving high channel throughput. Copyright © 2008 John Wiley & Sons, Ltd.     

Modelling and simulation of saturation region in double gate graphene nanoribbon transistors

Novel analytical models for surface field distribution and saturation region length for double gate graphene nanoribbon transistors are proposed. The solutions for surface potential and electric field are derived based on Poisson equation. Using the proposed models, the effects of several parameters such as drain-source voltage, oxide thickness and channel length on the length of saturation region and electric field near the drain are studied.     

A study of conversion coating development on aluminium in chromate/fluoride solutions using secondary ion mass spectrometry

A Cameca Ion Analyzer has been used to examine aluminium surfaces, covered by 73 nm thick barrier type anodic films, after natural immersion for 1–15 min in a chromate/fluoride conversion coating solution at 293 K. The conversion coating produced is essentially amorphous chromium-containing material, probably largely hydrated chromic oxide, but contains a cellular-type structure with aluminium and fluoride, probably as complex oxyfluoride, concentrated in the inter-cellular regions. The major role of the F^? ion is to remove the initial oxide film, maintain the surface active and permit nucleation and lateral growth of the conversion coating over it. The F^? ion is more aggressive towards anodic and other alumina than CrO₄^2? and PO₄^3? ions, without appearing to enter the anodic film material per se, but is also more aggressive towards the aluminium substrate than C1^? ion, acting initially at flaws and undermining the film.     

Measurement and Explanation of DC/RF Power Loci of an Active Patch Antenna

A case study of an active transmitting patch antenna revealed a characteristic loop locus of DC power versus RF output power as drive frequency was varied, with an operational bandwidth substantially smaller than the impedance bandwidth of the radiator. An approximate simulation technique, based on separation of the output capacitance of the power transistor, yielded easily visualized plots of power dependence on internal load impedance, and a simple interpretation of the experimental results in terms of a near‐resonance condition between the output capacitance and output packaging inductance.     

Health monitoring scheme‐based Forster resonance energy transfer nanocommunications in the Internet of Biological Nanothings

In this paper, a health monitoring approach for a targeted drug delivery (TDD) system taking into consideration the binding of drug to a target cell is proposed. The proposed scheme is mainly based on Forster resonance energy transfer (FRET) nanocommunications and the physical phenomenon such as protein–protein interactions in biological systems, in order to propose a molecular communication system with various forms for single and/or multiple ligand–receptor binding. Inspired by classical wireless communication system, the analysis of proposed scheme in terms of bit error rate (BER) and mutual information between the transmitter nanomachine (TN) and receiver nanomachine (RN) is presented. Subsequently, we are able to obtain a closed‐form expression for BER for the proposed scheme. The proposed scheme can be employed in the promising Internet of Biological Nanothings (IoBNT) paradigm. The numerical results reveal that the proposed scheme with multiple donors multiple acceptors system analogous to multiple input multiple output (MIMO) communication system is a superior scheme for transmission therapeutic drug information with achievable BER.     

Relation between hydrocarbon saturation and pore pressure evaluation for the Amal Field area,Gulf of Suez,Egypt

The study area is located between latitudes 28° 4′ 12″ to 28° 4′ 50″?N and longitudes 33° 35′ 12″ to 33° 35′ 34″?E mainly in the Amal Field, the offshore southern Gulf of Suez basin. Kareem Formation which is subdivided into Shagar and Markha members is the object of study through integrating the subsurface geologic studies, well log evaluation and the petrophysical laboratory measurements in order to better understand hydrocarbon potentialities of Kareem Formation in Amal Field, using ten wells (Amal-5, Amal-9, Amal-10AST, Amal-11, Amal-12, Amal-13ST, Amal-15ST, Amal-17ST, Amal-18, and Amal-19) different types of open hole well logs for petrophysical parameters (shale content, porosity and fluid saturation) determination. Also the porosities were determined by using the available sonic, density and neutron logs. Four wells (Amal-15 ST, Amal-17 ST, Amal-18 and Amal-19) have been selected for evaluating the pore pressure for Kareem Formation based on corrected drilling exponent (Dxc) calculation, flow line temperature data, background gases, mud density, hole configuration data and wireline logs. A matching was observed between pore pressure values and hydrocarbon saturation in the studied area.     

Synthesis and characterization of polymeric additives based on α-Olefin as pour point depressant for Egyptian waxy crude oil

Several strategies have been utilized to minimize the problems that causes losses of billions of dollars per year to the petroleum industry. Octadecene (OD) copolymerizes with styrene (S) at variable ratios of 1:1, 1:2, and its copolymers were obtained from alkylation by Friedel-Craft followed by esterification and amidation. Infrared spectra (IR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR) spectroscopy were performed to characterize the end products. Waxy crude oil (Blank PPT = 27°C) from NQ7 well, Qarun Petroleum Company, Western Desert, Egypt, was studied, and the results indicate that crude oil treated with the prepared copolymers at dosage 2,000 ppm depresses PPT to 6°C and enhances the paraffin inhibition (PI) to 80% compared with blank. Good results are obtained by using the highest molecular weight copolymer compared with others.     

Investigating Thermal Parameters of PVDF Sensor in the Front Pyroelectric Configuration

A metalized PVDF pyroelectric (PE) sensor was used as an optically opaque sensor and in a thermally thick regime for both sensor and sample, instead of a very thick sensor in the conventional front PE configuration. From the frequency dependence measurements, the normalized amplitude and phase signal were independently analyzed to obtain the thermal effusivity of the sensor. The differential normalized amplitude measured with water as a substrate was analyzed to determine the sensor thermal diffusivity. The PVDF thermal diffusivity and thermal effusivity agree with literature values. Then, from the known thermal parameters of the sensor, the thermal effusivity of a standard liquid sample, glycerol, and other liquids were obtained by the similar procedure.     

Oxidation Resistance of the Aluminide Coating Formed on Carbon Steels

Low and medium carbon steels were aluminized by the pack aluminizing technique using halideactivated pure-Al and Fe-Al packs. The effect of mixture composition, aluminizing temperatureand time and C content of the steel substrate on the structure and thickness of the aluminidelayer, and on the oxidation resistance was investigated. The optimum oxidation resistance canbe achieved with a low carbon steel substrate when the intermetallic phases Fe3Al and FeAlform the surface of the aluminide layer. In this case, the Al concentration at the surface of thealuminide coating is at least ≥15 wt pct. Formation of high Al concentration phases (FeAl3 andFe2Al5) during aluminizing should be avoided as they tend to embrittle the aluminide layer andreduce its oxidation resistance.