Analysis of Acceleration Effect in Data Dissemination in Vehicular Networks Using Rateless Codes

Mobility models of nodes have an important role in the evaluation of data dissemination protocols in vehicular ad hoc networks (VANETs). Many recent researches have used the constant velocity mobility models while vehicles have acceleration and their speeds change as they move. Because of the dynamic nature of VANETs, the network changes from a densely connected to the sparsely connected environment in a short time. In sparsely connected networks, it is said that vehicles move in clusters. In this paper, the constant acceleration mobility calculations for the sparsely connected network and its characteristics have been presented. These characteristics are usable for the evaluation of the data dissemination protocols in VANETs. The results show that acceleration affects the number of viewed clusters during the trip and the number of vehicles within a cluster. In fact, acceleration has a significant impact on the network sparsely connection. This matter shows that the appropriate data dissemination protocol should be used to study the acceleration effect which is applicable in sparse networks. The analysis in this research provides the necessary background for better understanding and accurate calculations for the evaluation of data dissemination in VANETs.     

FPGA based fast and high-throughput 2-slow retiming 128-bit AES encryption algorithm

This paper presents a high throughput digital design of the 128-bit Advanced Encryption Standard (AES) algorithm based on the 2-slow retiming technique on FPGA. The C-slow retiming is a well-known optimization and high performance technique. It can enhance designs with feedback loops and automatically rebalances the registers in the design. The C-slow retiming can break the critical path of the design into finer pieces to improve the throughput of the design. The complexity of the C-slow retiming on FPGA is to find the best register allocation in the data path of the design so that by increasing the number of registers, relocation of the registers to balance the AES architecture be in the best mode, and the critical path be optimally pipelined and improved. In this paper, architecture of the AES algorithm is implemented in the gate level by high-speed and breakable structures that are desirable for the 2-slow retiming. The Mix-columns transformation is implemented based on multiplication by constants 2 and 3 modules with combinational logic circuits. This work has been successfully verified and synthesized using Xilinx ISE 11 byVirtex-5, XC5VLX85 FPGA. The proposed implementation achieves a high throughput of 86 Gb/s and high maximum operation frequency of 671.524 MHz whereas the highest throughput and the highest operation frequency reported in the literature are 73.737 Gb/s and 576.07 MHz, respectively.     

Determination of pefloxacin and its main active metabolite in human serum by high-performance liquid chromatography

BACKGROUND: Investigation to see if there are key psychological risk indicators for autism in a random population study of children at 18 months of age; and to assess how well these discriminate children who receive a diagnosis of autism from other forms of developmental delay. METHOD: Sixteen thousand children in the southeast of England were screened for autism by their health visitor or GP, during their routine 18-month-old developmental check-up, using the CHAT (Checklist for Autism in Toddlers). From a previous high-risk study we predicted that children at 18 months of age who failed three items ('protodeclarative pointing', 'gaze-monitoring', and 'pretend play') would be at risk for receiving a diagnosis of autism. From other evidence, we further predicted that those 18-month-olds who failed one or two of the key items (either pretend play, or protodeclarative pointing and pretend play) would be at risk for developmental delay without autism. RESULTS: Twelve children out of the total population of 16,000 consistently failed the three key items. Of these, 10 (83.3%) received a diagnosis of autism. Thus, the false positive rate was 16.6% (2 out of 12 cases), and even these 2 cases were not normal. When the 10 children with autism were reassessed at 3.5 years of age, their diagnosis remained the same. Thus the false positive rate among the cases diagnosed with autism was zero. In contrast, of 22 children who consistently failed either protodeclarative pointing and/or pretend play, none received a diagnosis of autism, but 15 (68.2%) received a diagnosis of language delay. CONCLUSIONS: Consistent failure of the three key items from the CHAT at 18 months of age carries an 83.3% risk of autism; and this pattern of risk indicator is specific to autism when compared to other forms of developmental delay.     

Anodic behaviour of tin in maleic acid solution and the effect of some inorganic inhibitors

The anodic behaviour of a tin electrode in maleic acid solutions was investigated by potentiodynamic and chronopotentiometric methods. Measurements were conducted under different experimental conditions. The results demonstrated that the polarization curves exhibit active/passive transition. In active regions, tin dissolves as Sn²⁺ which is subsequently oxidized to Sn⁴⁺ and the dissolution process is controlled partly by diffusion of the solution species. The passivity is due to the presence of thin film of SnO₂ on the anode surface formed by dehydration of precipitated Sn(OH)₄. The active dissolution of tin increases with increasing acid concentration, temperature and scan rate. The potential transients showed that the passivation time decreases with increasing applied current density. The effect of adding increasing concentrations of CrO₄²⁻, MoO₄²⁻ and NO₂⁻ ions on the anodic behaviour of tin in maleic acid was studied. These ions inhibit the active dissolution of tin and promote the attainment of passivity. The extent of these changes depends upon the type and concentration of the inhibitor.     

Digital adaptive phase noise reduction in coherent optical links

Coherent optical links enable high-density constellations and, consequently, a higher throughput. However, the phase noise associated with the transmitter and the receiver lasers is a challenging issue in coherent lightwave systems. The authors present an approach that relies on using digital signal processing techniques to compensate for the laser phase-noise effects. The proposed approach exploits the digital processing power to address the problems arising from optical imperfections. The authors present an adaptive filtering scheme that reduces the effect of the laser phase noise and, consequently, relaxes the laser linewidth requirement. The proposed approach shows how the signal processing techniques can be exploited to compensate for the optical impairments by utilizing the continuing scale down in size and power in very large scale integration (VLSI) technology.     

Robust wireless location over fading channels

This paper develops an estimation algorithm for the time and amplitude of arrival of a known transmitted sequence over a single-path fading channel. The algorithm is optimized to enhance robustness to fast channel fading and low signal-to-noise ratio (SNR) conditions, which are common in wireless location applications. The paper also presents a noise and fading bias correction technique for amplitude of arrival estimation that improves the estimation accuracy significantly. The proposed algorithm is then applied to the case of code-division multiple-access (CDMA) wireless location finding for which the paper gives simulation results that demonstrate significant estimation accuracy improvement over known algorithms.     

Technetium-99m-MIBI myocardial SPECT: supine versus right lateral imaging and comparison with coronary arteriography

Myocardial perfusion SPECT using the prone position improves inferior wall counts and decreases motion problems as compared with the usual supine position. Nonetheless, it is not suitable for women. In addition, it is associated with artifactual anteroseptal defects and hot spots. METHODS: The right lateral (RL) position was evaluated instead of the prone position in 72 patients (26 women). RL imaging was performed immediately after the supine imaging during a routine 2-day 99mTc-sestamibi exercise protocol. The SPECT images were scored semiquantitatively by three physicians. Moreover, regional myocardial counts, as well as extent and severity of defects, were assessed by quantitative polar map analysis. RESULTS: All patients tolerated the RL position well and there was no significant patient movement in either position. Higher inferior myocardial counts per pixel were observed in the RL than in supine images. Inferior wall defects (especially mild ones) were more common in the supine than the RL images, whereas defects in other regions were not different. Quantitative analysis confirmed these findings. Analysis of 34 patients with recent coronary arteriography revealed an overall coronary artery disease (CAD) supine- and RL-imaging specificity of 50% and 75%, respectively, and the sensitivities of both were 93%. Right CAD sensitivity, specificity and normalcy rates for the supine position were 100%, 44% and 55%, whereas those of the RL position were 94%, 75% and 90%, respectively. CONCLUSION: The RL position improves CAD diagnostic accuracy, particularly right CAD, without significant artifacts in other myocardial regions. Unlike the prone position, the RL position is well tolerated by both women and men.     

Changes in blocking mechanisms during membrane processing of pomegranate juice

The effect of pressure, velocity, pretreatment, membrane type and pore size on fouling mechanisms were evaluated. Pomegranate juice was treated with polyvinylidene fluoride (PVDF) 0.22 μm and mixed cellulose ester (MCE) 0.1 μm at different pressures. Cake formation which was the dominant mechanism was formed in the first stages of process and, as the filtration proceeded, intermediate, standard, and complete blocking, respectively occurred at higher pressure (5 kPa). At lower pressure (0.5 kPa) the last mechanism did not occur. Results showed that cake formation was the only mechanism in MCE 0.22 μm, however, others occurred with MCE 0.1 μm and PVDF 0.22 μm. Using MCE 0.22 μm prior to MCE 0.025 μm can reduce the role of cake formation in pore blocking. Evaluation of the impact of velocity showed that at the higher velocity (0.53 m s⁻¹) the complete blocking occurred faster than at the lower velocity (0.09 m s⁻¹).