A MRF model-based segmentation approach to classification formultispectral imagery

An unsupervised segmentation approach to classification of multispectral image is suggested here in Markov random field (MRF) frame work. This work generalizes the work of Sarkar et al. (2000) on gray value images for multispectral images and is extended for landuse classification. The essence of this approach is based on capturing intrinsic characters of tonal and textural regions of any multispectral image. The approach takes an initially oversegmented image and the original. multispectral image as the input and defines a MRF over region adjacency graph (RAG) of the initially segmented regions. Energy function minimization associated with the MRF is carried out by applying a multivariate statistical test. A cluster validation scheme is outlined after obtaining optimal segmentation. Quantitative evaluation of classification accuracy of test data for three illustrations are shown and compared with conventional maximum likelihood procedure. Comparison of the proposed methodology with a recent work of texture segmentation in the literature has also been provided. The findings of the proposed method are found to be encouraging     

Transhorizon VHF TV signal propagation over mixed land-sea paths

The propagation characteristics of Rupavahini TV transmissions originating from Sri Lanka on channels 5 and 8 and monitored in southern India are studied. The receiving sites are chosen to provide mixed land-sea paths. The propagation characteristics of these mixed paths are influenced by sea-surface refractivity gradients and land-sea interactions. The analysis of the data indicates that different propagation mechanisms prevail for various percentages of time. Sometimes signal levels on the order of 10-dB below free space level are also observed, particularly in premonsoon months, which is due to the occurrence of ducting conditions prevailing in this region. Some observations of the distance dependence of the channel 5 signal show that the path loss increases by 10 dB for every 100 km of distance     

A model of front-illuminated n+-p-p+high-efficiency silicon solar cell

A realistic model of a front-illuminated n⁺-p-p⁺ silicon solar cell is developed by solving the current continuity equations for minority carriers in the quasi-neutral regions in steady state, assuming the light in the cell is trapped as a result of multiple reflections at the front and the back of the cell. This model is used to study the effects of the front emitter thickness and doping level and the light trapping on the J-V characteristic and thereby on the open-circuit voltage, short-circuit current density, curve factor, and the efficiency of the cell. A textured cell with an emitter thickness in the range of 0.3-1.0 μm with its doping ≈5×10¹⁸ cm^-3 and the recombination velocities of minority carriers as large as 200 cm/s at the n⁺ front surface and 10 cm/s at the back of the p base can exhibit an efficiency in excess of 26% (under AM 1.5 sunlight of 100 mW/cm² intensity) at 25°C if the light reflection losses at the front surface can be made small     

Analysis of joule heating in electrophoretic processes

Joule heating appears to be the most limiting factor in the scale-up of many electrophoretic processes. The heat equation is solved for the case of Counteracting Chromatographic Electrophoresis (cylindrical gel) and the importance of autothermal heating effect is emphasized.     

Comparison of lantadenes content and toxicity of different taxa of the lantana plant

Three taxa of the lantana plant (Lantana camara var.Aculeata) I (white-pink), II (yellow-pink), and III (yellow-red)-differed in the content of lantadenes and compounds X, Y, and Z. Lantadene A, lantadene B, and lantadene C were the major lantadenes of taxon III. It contained small amounts of lantadene D. Taxa I and II contained very small amounts of lantadene A and lantadene B. Compounds X, Y, and Z were the major constituents of taxa I and II, and they constituted 59% and 92% of the total constituents in these taxa, respectively. Ingestion of lantana leaf powder of taxon III by male guinea pigs caused severe hepatotoxicity. Taxon I elicited mild hepatotoxicity in one out of six animals while taxon II was nontoxic. The biological and ecological significance of the presence of high amounts of compounds X, Y, and Z in taxa I and n is not known.     

Comprehensive microstructural characterization in modified 9Cr-1Mo ferritic steel by ultrasonic measurements

Modified 9Cr-1Mo ferritic steel (T91/P91) has been subjected to a series of heat treatments consisting of soaking for 5 minutes at the selected temperatures, starting from the α-phase region (1073 K) to the γ + δ-phase region (1623 K), followed by oil quenching. Hardness measurements, microstructural features, and grain-size measurements by the linear-intercept method have been used for correlating them with the ultrasonic parameters. Ultrasonic velocity and attenuation measurements, and spectral analysis of the first backwall echo have been used for characterization of the microstructures obtained by various heat treatments. As the soaking temperature increased above Ac ₁, the ultrasonic velocity decreased because of the increase in the volume fraction of martensite in the structure. There were sharp changes in the ultrasonic velocities corresponding to the two critical temperatures, Ac ₁ and Ac ₃. Ultrasonic longitudinal- and shear-wave velocities were found to be useful in identifying the Ac ₁ and Ac ₃ temperatures and for the determination of hardness in the intercritical region. However, ultrasonic attenuation and spectral analysis of the first backwall echo were found to be useful to characterize the variation in the prior-austenitic grain size and formation of δ ferrite above the Ac ₄ temperature. The scattering coefficients have been experimentally determined for various microstructures and compared with the theoretically calculated value of the scattering coefficients for iron reported in literature.     

Colorectal manifestations of endocrine disease

PURPOSE: The aim of this review is to alert the colon and rectal surgeon to the colorectal manifestations of endocrine disease. METHODS: This report was obtained by a review of the medical literature. Endocrine disease may initially present as a symptom felt to be referable to colorectal disease. Furthermore symptoms of well-established endocrine disorders may have refractory colorectal symptoms. RESULTS: Constipation is the most common gastrointestinal symptom of diabetics; however, in patients with brittle diabetes, diarrhea may be chronic and intermittent. Unexplained diarrhea, despite an exhaustive work-up for an etiology, should alert the clinician to the possibility of a pancreatic endocrine tumor. Thyroid disorders, depending on activity of the gland, may have refractory constipation, diarrhea, or steatorrhea as the only presenting symptoms. Constipation is a common symptom of hypercalcemia, secondary to hyperparathyroidism. Primary hyperparathyroidism has been associated with increased incidence of malignancies, specifically of colonic origin. In patients with acromegaly a threefold to eightfold increased risk of colon carcinoma or adenomatous polyps is seen. Chronic adrenal insufficiency may present initially as diarrhea and malabsorption. The adrenal gland is a frequent site of metastases from colorectal cancer. Pheochromocytomas may be a cause of occult gastrointestinal bleeding or ischemic colitis. CONCLUSION: Unexplained symptoms referable to the colon and rectum should alert the clinician to the possibility of an underlying endocrine disorder.