Automated analysis for scintigraphic evaluation of gastric emptying using invariant moments

This study introduces a method for automated analysis of the standard solid-meal gastric emptying test. The purpose was to develop a diagnostic tool to characterize more reproducibly abnormalities of solid-phase gastric emptying. The processing of gastric emptying is automated using geometrical moments that are invariant to scaling, rotation, and shift. Twenty subjects were studied. The first step was to obtain images of the stomach using a nuclear gamma camera immediately after the subject had eaten a radio-labeled meal. The second step was to process and analyze the images by a recently developed automated gastric emptying analysis (AGEA) method, which determines the gastric contour and the geometrical properties include such parameters as area, centroid, orientation, and moments of inertia. Statistical tests showed that some of the moments were sensitive to the patient's gastric status (normal versus abnormal). The difference between the normal and abnormal patients became noticeable approximately 1 h after meal ingestion.     

Target image tracking using a nonlinear filter based on Pontryagin minimum principle

The major contribution of this technical note is the introduction of a new nonlinear filter, based on Pontryagin minimum principle and the method of invariant imbedding, as applied to spatial filtering of FLIR image sequences. This filler is used to improve the signal-to-noise ratio (SNR) of each frame. The target center is then estimated using different approaches. It is shown, through Monte Carlo simulation, that the proposed methods improve the accuracy of the estimate of the target center by 100 pecent on the average, compared to the correlation algorithm.     

Improvement in adaptive noise canceling using a nonlinear filter based on the pontryagin minimum principle

This paper introduces a new nonlinear filter that is used for adaptive noise canceling. The derivation and convergence properties of the filter are presented. The performance, as measured by the root mean square error between the signal and its estimate, is compared with that of the commonly used least mean square (LMS) algorithm. It is shown, through simulation, that the proposed nonlinear noise canceler has, on the average, better performance than the LMS canceler. The proposed adaptive noise canceler is based on the Pontryagin minimum principle and the method of invariant imbedding. The computational time for the proposed method is about 10% of that of the LMS, in the studied cases, which is a substantial improvement.     

Some aspects of the electrical and thermal properties of ammonium hydrogen tartrate

The relative permittivity (?) and the electrical resistivity (?) were measured at varying temperature from 310 up to 490 K for polycrystalline samples of ammonium hydrogen tartrate (AHT), NH₄HC₄H₄O₆. The measured parameters revealed that the compound undergoes successive solid-state structural phase transitions at ~ 368 K, 428 K and ~ 473 K, in addition to a probable change in the conduction mechanism at ~ 333 K. A differential thermal analysis (DTA) thermogram and a thermogravimetric analysis (TGA) plot were also performed from room temperature (~ 300 K) up to the melting point. The DTA results strongly support the existence of the above-mentioned solid-state phase transitions, whereas the TGA plot indicates the absence of any actual loss in weight in the transition temperature regions. The data are correlated to the reorientational motion of the NH₄ ⁺ ion, combined with the arrangement of the molecules in their crystals and in particular the hydrogen bonding system.     

An Updated Comprehensive Literature Review of Phenol Hydrogenation Studies

Catalysis Letters - Cyclohexanone is an important industrial intermediate to produce nylons. The main industrial routes for cyclohexanone manufacture used cyclohexane and phenol as feedstock. The...     

Location update optimization in personal communication systems

Mobility tracking is concerned with finding a mobile subscriber (MS) within the area serviced by the wireless network. The two basic operations for tracking an MS, location updating and paging, constitute additional load on the wireless network. The total cost of updating and paging can be minimized by optimally dividing the service area into location registration (LR) areas. There are various factors affecting this cost, including the mobility and call patterns of the individual MS, the shape, size and orientation of the LR area, and the method of searching for the MS within the LR area. Based on various mobility patterns of users and network architecture, the design of the LR area is formulated as a combinatorial optimization problem. The objective is to minimize the location update cost subject to a constraint on the size of the LR area. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fabrication of electrospun nickel sulphide nanoparticles onto carbon nanofibers for efficient urea electro-oxidation in alkaline medium

To design and synthesize a noble-metal free electrocatalyst with increased efficiency and stability during urea electro-oxidation in alkaline solution is still an important challenge in the electrocatalytic field. In this work, carbon nanofibers were decorated with nickel sulphide nanoparticles [NiS@CNFs] through the electrospinning technique with subsequent heating into an argon atmosphere at 900 °C for 2 h. This formed nanomaterial was extensively characterized through X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Raman spectroscopy and N₂ adsorption-desorption measurements. A conductive network of intertwined CNFs was clearly detected by FE-SEM analysis technique with varied diameters in the range of 0.6–1 μm. A highly porous nature could be suggested after incorporating NiS nanospecies resulting in increased specific surface area and valuable electrocatalytic activity for urea molecules electro-oxidation. The pore size distribution curves showed a decreased average pore diameter for NiS@CNFs nanocomposite by 2.53 folds when compared to that at CNFs. The electroactivity of NiS@CNFs nanomaterial for catalyzing urea electro-oxidation was investigated using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy measurements. Increased activity of this nanocatalyst was registered when urea molecules were added in increased concentrations into KOH solution. Lowered resistance values were also obtained describing the charge transfer process to confirm the feasibility of the studied reaction at NiS@CNFs surface. Moreover, its drawn chronoamperogram showed a stable performance during operation for long periods revealing a lowered catalytic decay. Accordingly, the aforementioned results of our fabricated nanomaterial could provide a good guide for fabricating suitable electrocatalysts for various electrocatalytic purposes.     

A tracking filter for maneuvering sources

An adaptive filter that is based on the Pontryagin minimum principle and the method of invariant imbedding is introduced and applied to the problem of tracking maneuvering sources. The major advantages of this approach are: (1) no model for the target dynamics is required, and (2) the signal-to-noise ratio of the observation and stations need to be known. The performance of the proposed approach (with unknown system dynamics) is compared to that of the extended Kalman filter (with known system dynamics) for the maneuvering reentry vehicle. Examples are given for different target scenarios