Exact and approximate analytic solutions of the nonlinear convective fin problem with temperature-dependent thermal conductivity

This article shows that the well-known nonlinear boundary value problem of the differential equation for temperature distribution of convective straight fins with temperature-dependent thermal conductivity is exactly solvable in an implicit form. Furthermore, an exact solution in an explicit form is derived. Also, an accurate analytic solution (series solution) is obtained by a new variation of the Adomian decomposition method.     

Individual Influence of Climate Variability Indices on Annual Maximum Precipitation Across the Global Scale

Water Resources Management - Studying the influence of climate variability indices on extreme precipitation will help to understand the variability of extreme precipitation. However, the influence...     

Persistence of the saddle-node bifurcation for nonlinear systems with slow unmodeled dynamics

This paper investigates the robustness of the saddle-node bifurcation for nonlinear systems under the addition of slow unmodeled dynamics. The robustness is examined in terms of existence and system behavior after bifurcation. Under fairly general conditions, it is shown that if the reduced model of a physical system encounters a saddle-node bifurcation due to a varying parameter, then the original model which includes small unmodeled dynamics will also encounter a saddle-node bifurcation. An error bound is derived between the bifurcation values and the bifurcation points of the reduced model and that of the original model. Furthermore, it is shown that the dynamics after the saddle-node bifurcation of the reduced model and that of the original model are approximately the same. The persistence and non-persistence of saddle-node bifurcations are illustrated by several examples.This work was supported in part by the NSF under grant numbers ECS-8957878 and ECS-8913074, by EPRI contract RP8010-8, and by Taipower Company.     

An efficient hardware implementation of parallel EBCOT algorithm for JPEG 2000

With the augmentation in multimedia technology, demand for high-speed real-time image compression systems has also increased. JPEG 2000 still image compression standard is developed to accommodate such application requirements. Embedded block coding with optimal truncation (EBCOT) is an essential and computationally very demanding part of the compression process of JPEG 2000 image compression standard. Various applications, such as satellite imagery, medical imaging, digital cinema, and others, require high speed and performance EBCOT architecture. In JPEG 2000 standard, the context formation block of EBCOT tier-1 contains high complexity computation and also becomes the bottleneck in this system. In this paper, we propose a fast and efficient VLSI hardware architecture design of context formation for EBCOT tier-1. A high-speed parallel bit-plane coding (BPC) hardware architecture for the EBCOT module in JPEG 2000 is proposed and implemented. Experimental results show that our design outperforms well-known techniques with respect to the processing time. It can reach 70 % reduction when compared to bit plane sequential processing.     

An evaluation of the cooling effect efficiency of the oasis structure in a Saharan town through remotely sensed data

This paper reports a study of how vegetation affects the formation of an Oasis Cool Island (OCI) in a dry climate, and aims to quantify the effectiveness of the oasis structure on the cooling effect by a comparative analysis of two oasis models: traditional oasis and modern oasis. The Landsat8 data of the hottest summer day was required, treated and analysed. In addition, all palm groves were classed and mapped using the ArcGIS 10.2 platform. Our results show that the traditional oasis has the lowest values of Land Surface Temperature (LST) which generates a strong cooling intensity (OCI = ?7.95 °C). Furthermore, the study suggests that Planting Density (PD) is a determining factor of OCI rather than the size of vegetation cover. Thus, the study provides information for urban planners seeking to create a favourable microclimate through vegetation management.     

High efficiency slotted photonic crystal waveguides for the determination of gases using mid-infrared spectroscopy

We present the design and analysis of a high efficiency slotted photonic crystal waveguide for gas sensing applications in the mid-infrared wavelength range. We designed the slotted photonic crystal waveguide structure by engineering the interfaces between the input and output slot waveguides and a resonant coupler. Coupling and transmission spectra of the sensor have been modeled using the three-dimensional finite-difference time domain method. The sensing principle is based on the shift of the upper band edge of the sensor output transmission spectrum which arises due to changes in the ambient refractive index. Transmission spectrum and sensitivity of the proposed sensor are analyzed by tuning the radii of the air holes localized on each side of the slot. The results show that a change of the refractive index of the gas by 10^?4 leads to a shift of the upper band edge wavelength by 540?pm which corresponding to a sensitivity of 1720?nm per refractive index unit. The proposed design may be an ideal platform for developing mid-infrared gas sensing devices characterized by high coupling efficiencies and high sensitivities.     

Implicit consensus clustering from multiple graphs

Data Mining and Knowledge Discovery - Dealing with relational learning generally relies on tools modeling relational data. An undirected graph can represent these data with vertices depicting...     

A novel multilevel carrier-based PWM-control method for GTO inverter in low index modulation region

Gate turn offs (GTOs) have an inherent minimum ON-OFF time, which is needed for their safe operation. For GTO-based three-level or neutral-point-clamped (NPC) inverters, this minimum ON-OFF pulsewidth limitation results in a distortion of the output voltage and current waveforms, especially in the low index modulation region. Some approaches have been previously proposed to compensate for the minimum ON pulse. However, these methods increase the inverter switching losses. Two new methods of pulsewidth-modulation (PWM) control based on: 1) adding a bias to the reference voltage of the inverter and 2) switching patterns are presented. The former method improves the output waveforms, but increases the switching losses; while the latter improves the output waveforms without increasing the switching losses. The fluctuations of the neutral-point voltage are also reduced using this method. The theoretical and practical aspects as well as the experimental results are presented in this paper.     

Removal of lead(II) from water using activated carbon developed from jujube stones,a low-cost sorbent

The preparation of activated carbon from jujube stones with H₂SO₄ activation and its ability to remove lead from aqueous solutions were reported in this study. The surface structure of the activated carbon was characterized by various physico-chemical methods. Sorption studies were carried out by varying the initial metal ion and the pH: the amount of sorbed Pb(II) ions increased with increasing pH and initial Pb(II) ions concentration. The removal of lead ions was rapid and the kinetic of sorption can be well described by pseudo-second order modelling. The Langmuir model conveniently fits the data of isotherm experiments and the monolayer sorption capacity of Pb(II) ions was determined as 71.43 mg/g at pH 6.0 and 25°C. These results showed that activated carbon prepared from jujube stones could be considered for application as a potential sorbent for the removal of lead from wastewaters.     

Natural occurrence of ochratoxin A in Tunisian cereals

Ochratoxin A (OTA) is a mycotoxin produced by several fungal species from Aspergillus and Penicillium genera. It is widespread in food and feed and its occurrence has been reported in cereals, cereal-derived products, dried fruits and spices. This mycotoxin was implicated in several human and animal pathologies such as the Balkan Endemic Nephropathy (BEN) and the Tunisian Chronic Interstitial Nephropathy (CIN) of unknown cause. In Tunisia, a clear correlation has been established between the consumption of OTA contaminated food and the induction of specific pathologies. Thereby, OTA was detected in human blood and tissues. The aim of our study was to investigate the presence of OTA in widely consumed cereals commercialized in Tunisia. The analytical methods used in our study involved the extraction of OTA by acidified toluene, immunoaffinity (IAC) clean-up and HPLC quantification with fluorescence detection. Levels and percentages of OTA contamination in different types of cereals, 110 wheat, 103 barley, 113 sorghum and 96 rice samples, were evaluated with incidences of 38%, 40%, 38% and 28%, respectively. The average of contamination by OTA found were 55, 96, 44 and 117 μg/kg, respectively, for wheat, barley, rice and sorghum. Our results showed that contamination percentages and levels in the period from 2004 to 2005 were higher then usual norms (5.0 μg OTA/kg) established by the European commission in 2002. The present report is the first one ever carried out on the natural occurrence of OTA in cereals, largely consumed by the Tunisian population.