Similar admittance behavior of amorphous silicon carbide and nitride dielectrics within the MIS structure

PECVD grown a-SiNx:H and a-SiCx:H films were investigated as dielectric films in the form of metal/insulator/p-silicon (MIS) structures. AC admittance of MIS structures was measured as a function of dc gate bias voltages and frequencies (1-1000 kHz) of the superimposed ac bias voltage (10 mV). For each applied bias voltage (from accumulating to inverting bias regimes), temperature (T) dependence of both capacitance (C) and conductance (G/ω) were measured to investigate majority/minority carrier behavior under various frequencies ω (kHz-MHz) as parameters. C and G/ω-T-ω measurements reveal that observed pairs of capacitance steps and conductance peaks are related to traps lying on the same energy value, residing in the insulator and at the interface of insulator/semiconductor structure and differing only through capture cross-sections. On the other hand, surface band bending (ψ_s) of silicon and activation energy (E_A) deduced from the Arrhenius plot of the frequency vs. reciprocal temperature as a function of gate bias (V_G) seem linearly dependent, implying that E_A reflects the ψ_s variation.     

Improving the accuracy of contact-type drawbead elements in panel stamping analysis

A finite element modeling technique is proposed to improve the accuracy of contact-type drawbead elements in panel forming analyses, and a performance assessment in terms of part border and thickness predictions is presented in conjunction with panel stamping experiments of two automotive sheets. Inherent model limitations causing incorrect part geometry and thickness predictions are, firstly, evaluated considering blank deformations on a plain–strain section of a stamping die. The influence of omitted drawbead geometry and overestimated drawbead exit thickness are described analytically, and a closed form expression is obtained to correct draw-in model error. Then a sectional deformation model is used to calculate restraint force and drawbead exit thickness for a particular blank and drawbead design. The proposed technique is applied in process modeling of polygon shaped panels made of draw-quality and bake-hardenable steels. Three bead penetrations were investigated in process simulations as well as in stamping experiments. The same blankholder force was applied in all process conditions. Computed draw-in and thickness distributions were compared with on-part measurements using an experimental panel-draw die. It was determined that drawbead models based on force parameters only resulted in remarkably high thickness values at the die entry and mostly overestimated draw-in along panel border lines. An evaluation of thickness distributions computed with proposed technique showed an improved correlation with experiment results of both blank materials and confirmed the use of the drawbead exit thickness as a drawbead modeling parameter. Effects of bead penetration on panel border lines were also simulated in accord with stamping experiments.     

A Review of Dehydration of Various Industrial Sludges

Wastewater characteristics and sludge generation potential of point source categories are reviewed critically. Novel industry-specific sludge dewatering/drying solutions necessary to establish a sustainable model are examined through a detailed literature survey. Knowledge of sludge properties is one of the most critical issues needed to design dewatering/drying equipment. This study focuses on industrial wastewater/sludge characterization. In addition, a comprehensive review of current drying models and technologies is also presented. A summary of the results derived from a novel thin-film-based photonic sludge dewatering/drying study is outlined as an alternative approach for industrial sludge control. Sludge was dried in a tubular quartz reactor (TQR), the inner surface of which was coated with a TiO₂ thin film. The TQR was irradiated with UV A, UV B, and UV C lamps. The consumed and generated energy fluxes through endergonic and exergonic reactions driven by photolysis and photocatalysis were investigated. In addition, the variations in sludge dewatering/drying characteristics were also examined and compared with conventional methods to evaluate the energy requirements.     

Release of salicylic acid through poly(vinyl alcohol)/poly(vinyl pyrrolidone) and poly(vinyl alcohol‐g‐N‐vinyl‐2‐pyrrolidone) membranes

A controlled release profile of salicylic acid (SA) for transdermal administration has been developed. Poly (vinyl alcohol) (PVA) and Poly(vinyl alcohol)/Poly(vinyl pyrrolidone) (PVP) blended preparations were used to prepare the membranes by solvent‐casting technique. The release of the drug from the membranes was evaluated at in vitro conditions. The effects of PVA/PVP (v/v) ratio, pH, SA concentration and temperature were investigated. 60/40 (v/v) PVA/PVP ratio was found to be the best ratio for the SA release. Increase in pH and temperature was observed to increase the transport of SA. Instead of blending PVA with PVP, N‐Vinyl‐2‐pyrrolidone (VP) was grafted onto the PVA and the delivery performance for SA was compared with that of the blended PVA/PVP membranes. Grafted membranes gave higher transport percentages than the blended membranes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1244–1253, 2006     

Performance of ground blast furnace slag and ground basaltic pumice concrete against seawater attack

The aim of this research work is to investigate the seawater resistance of the concrete incorporating ground blast furnace slag (GBS) and ground basaltic pumice (GBP) each separately or both together. The variable investigated in this study is the level of fine aggregate replacement by GBS and GBP. Compressive strength measured on 150 mm cubes was used to assess the changes in the mechanical properties of concrete specimens exposed to seawater attack for 3 years.

Differential scanning calorimeter was used to evaluate the microstructure of the specimens under seawater attack. The effects of exposure were determined by direct measurement of the mass loss of steel bars, embedded in the mortar after 1, 2 and 3 years. The abrasion of concrete was also determined according to mass loss of specimens.

The test results showed that the presence of GBS and GBP had a beneficial effect on the compressive strength loss due to seawater attack and abrasion value. The results create perspectives of forecasting the durability of concrete depending on the types and amount of additives. Furthermore, specimen CSP80 was found to have higher seawater attack resistance than that of the reference concrete. This improvement can be explained partly by the decrease in the permeability of the specimen and partly by the seawater resistance of the additives. Additionally, the corrosion percentage obtained in the reference specimen was higher than all other specimens.     

Effect of wastewater composition on archaeal population diversity

Distribution and occurrence of Archaea and methanogenic activity in a laboratory scale, completely mixed anaerobic reactor treating pharmaceutical wastewaters were investigated and associated with reactor performance. The reactor was initially seeded with anaerobic digester sludge from an alcohol distillery wastewater treatment plant and was subjected to a three step feeding strategy. The feeding procedure involved gradual transition from a glucose containing feed to a solvent stripped pharmaceutical wastewater and then raw pharmaceutical wastewater. During the start-up period, over 90% COD removal efficiency at an organic loading rate (OLR) of 6 kg COD m(-3)d(-1) was achieved with glucose feeding, and acetoclastic methanogenic activity was 336 ml CH4 gTVS(-1)d(-1). At the end of the primary loading, when the feed contained solvent stripped pharmaceutical wastewater at full composition, 71% soluble COD removal efficiency was obtained and acetoclastic methanogenic activity decreased to half of the rate under glucose feed (166 ml CH4 gTVS(-1)d(-1)). At the end of secondary loading with 60% (w/v) raw pharmaceutical wastewater, COD removal dropped to zero and acetoclastic methanogenic activity fell to less than 10 ml CH4 gTVS(-1)d(-1). Throughout the course of the experiment, microbial community structure was monitored by DGGE analysis of 16S rRNA gene fragments. Five different archaeal taxa were identified and the predominant archaeal sequences belonged to methanogenic Archaea. Two of these showed greatest sequence identity with Methanobacterium formicicum and Methanosaeta concilii. The types of Archaea present changed little in response to changing feed composition but the relative contribution of different organisms identified in the archaeal DGGE profiles did change.     

Potential Anomaly Separation and Archeological Site Localization Using Genetically Trained Multi‐level Cellular Neural Networks

In this paper, a supervised algorithm for the evaluation of geophysical sites using a multi‐level cellular neural network (ML‐CNN) is introduced, developed, and applied to real data. ML‐CNN is a stochastic image processing technique based on template optimization using neighborhood relationships of the pixels. The separation/enhancement and border detection performance of the proposed method is evaluated by various interesting real applications. A genetic algorithm is used in the optimization of CNN templates. The first application is concerned with the separation of potential field data of the Dumluca chromite region, which is one of the rich reserves of Turkey; in this context, the classical approach to the gravity anomaly separation method is one of the main problems in geophysics. The other application is the border detection of archeological ruins of the Hittite Empire in Turkey. The Hittite civilization sites located at the Sivas‐Altinyayla region of Turkey are among the most important archeological sites in history, one reason among others being that written documentation was first produced by this civilization.     

NODIC: a novel distributed clustering routing protocol in WSNs by using a time-sharing approach for CH election

Wireless Networks - Due to the battery limitations, energy-efficient routing is one of the most important issues in WSNs. In this paper, a novel distributed clustering routing protocol (NODIC) is...     

Multipath channel identification by using global optimization in ambiguity function domain

A new transform domain array signal processing technique is proposed for identification of multipath communication channels. The received array element outputs are transformed to delay-Doppler domain by using the cross-ambiguity function (CAF) for efficient exploitation of the delay-Doppler diversity of the multipath components. Clusters of multipath components can be identified by using a simple amplitude thresholding in the delay-Doppler domain. Particle swarm optimization (PSO) can be used to identify parameters of the multipath components in each cluster. The performance of the proposed PSO-CAF technique is compared with the space alternating generalized expectation maximization (SAGE) technique and with a recently proposed PSO based technique at various SNR levels. Simulation results clearly quantify the superior performance of the PSO-CAF technique over the alternative techniques at all practically significant SNR levels.     

A simple simultaneous geometric and intensity correction method for echo-planar imaging by EPI-based phase modulation

A technique, based on Echo planar imaging (EPI)-based phase modulation factor maps, is described for correction of EPI distortions resulting from field inhomogeneity. In this paper, a phase modulation factor was employed to remove the distortions. The phase modulation factor was obtained experimentally by collecting EPI images with a spin-echo (TE) spacing, deltaTE, equal to the inter-echo time interval, T(i). Then, the distortions resulting from the field inhomogeneity were removed by modulating the kappa-space data with the phase modulation factor. One of the advantages of this method is that it requires only a few extra scans to collect the information on field inhomogeneity. The proposed method does not require a phase unwrapping procedure for field inhomogeneity correction and, hence, is easier to implement, compared to other techniques. In addition, it corrects geometric distortion as well as intensity distortions simultaneously, which is robust to external noise or estimation error in severely distorted images. In this work, we also compared the proposed technique with others including, a) interpolation method with EPI-based displacement maps, and b) modulation method with phase modulation factor maps generated from spin-echo images. The results suggest the proposed technique is superior in correcting severely distorted images.