Infiltration of Water into Soil with Cracks

This paper presents the physical basis of the FRACTURE submodel for simulating infiltration of precipitation∕irrigation water into relatively dry, cracked, fine-textured soils. The FRACTURE submodel forms part of the HYDRUS-ET variably saturated flow∕transport model. Infiltration into the soil matrix is formally divided into two components: (1) Vertical infiltration through the soil surface; and (2) lateral infiltration via soil cracks. The first component is described and solved using the 1D Richards' equation. Excess water that does not infiltrate through the soil surface is either considered to be runoff, if no soil cracks are present, or routed into soil cracks from where it may laterally infiltrate into the soil matrix. Horizontal infiltration from soil cracks into the soil matrix is calculated using the Green-Ampt approach and incorporated as a positive source∕sink term Sf in the Richards' equation describing flow in the matrix. In addition to the hydraulic properties of the soil matrix, the FRACTURE submodel requires parameters characterizing the soil cracks, notably the specific crack length per surface area lc and the relationship between crack porosity Pc and the gravimetric soil water content w. An example problem shows that infiltration from soil cracks can be an important process affecting the soil water regime of cracked soils. A comparison with the more traditional approach, involving surface infiltration only, indicates important differences in the soil water content distribution during a rainfall∕irrigation event. This extension of the classical approach to include crack infiltration significantly improves the identification and prediction of the soil water regime.     

A Study of the Properties of Compacts from Silicified Microcrystalline Celluloses

ABSTRACT

The paper deals with a study of tensile strength and disintegration time of compacts made from silicified microcrystalline celluloses, Prosolv SMCC 90, and Prosolv HD 90, in dependence on compression force, addition of two types of lubricants, and two active ingredients. The lubricants were magnesium stearate and sodium stearyl fumarate in a concentration of 0.5%, the active ingredients being ascorbic acid and acetylsalicylic acid in a concentration of 50%.

Prosolv SMCC 90 proved to be better compatible than Prosolv HD 90; the compacts were of higher strength, which was markedly increased with increasing compression force. Prosolv HD 90 was more sensitive to additions of lubricants, and a greater decrease in strength was recorded due to the influence of sodium stearyl fumarate. The effect of lubricants on the strength of compacts in the presence of active ingredients was not identical. The disintegration time of compacts from Prosolv HD 90 without as well as with lubricants was shorter than from Prosolv SMCC 90 and was increasing with increasing compression force. Disintegration time was increased with added lubricants, and it was markedly shortened by addition of active ingredients. Compacts containing ascorbic acid possessed a shorter disintegration time than those containing acetylsalicylic acid, and it was not markedly influenced by the presence of lubricants.     

Geometric Bone Modeling: From Macro to Micro Structures

There is major interest within the bio-engineering community in developing accurate and non-invasive means for visualizing, modeling and analyzing bone micro-structures. Bones are composed of hierarchical bio-composite materials characterized by complex multi-scale structural geometry. The process of reconstructing a volumetric bone model is usually based upon CT/MRI scanned images. Meshes generated by current commercial CAD systems cannot be used for further modeling or analysis. Moreover, recently develop...     

Visualization of trends using RadViz

Data mining is sometimes treating data consisting of items representing measurements of a single property taken in different time points. In this case data can be understood as a time series of one feature. It is no exception when the clue for evaluation of such data is related to their development trends as observed in several successive time points. From the qualitative point of view one can distinguish three basic types of behaviour between two neighbouring time points: the value of the feature is stable (remains the same), it grows or it falls. This paper is concerned with identification of typical qualitative development patterns as they appear in the windows of given length in the considered time-stamped data and their utilization for specification of interesting subgroups.     

Anisotropic Magnetoresistance of GaMnAs Ferromagnetic Semiconductors

The angular dependence of the magnetoresistance has been studied for two sets of samples: annealed and hydrogenated, respectively. Different behavior of magnetoresistance anisotropy has been discussed in terms of change of scattering rate and/or introduction of strain during treatment.     

GYO reductions,canonical connections,tree and cyclic schemas,and tree projections

Database schemas may be partitioned into two subclasses: three schemas and cyclic schemas. The analysis of tree vs . cyclic schemas introduced the concepts of GYO reductions, canonical connections, and tree projections. This paper investigates the intricate relationships among these concepts in the context of universal relation databases.     

Performance intensification of Prague wastewater treatment plant.

Prague wastewater treatment plant was intensified during 1994--1997 by construction of new regeneration tank and four new secondary settling tanks. Nevertheless, more stringent effluent limits and operational problems gave rise to necessity for further intensification and optimisation of plant performance. This paper describes principal operational problems of the plant and shows solutions and achieved results that have lead to plant performance stabilisation. The following items are discussed: low nitrification capacity, nitrification bioaugmentation, activated sludge bulking, insufficient sludge disposal capacity, chemical precipitation of raw wastewater, simultaneous precipitation, sludge chlorination, installation of denitrification zones, sludge rising in secondary settling tanks due to denitrification, dosage of cationic polymeric organic flocculant to secondary settling tanks, thermophilic operation of digestors, surplus activated sludge pre-thickening, mathematical modelling.     

Auditory nerve representation as a front-end for speech recognition in a noisy environment

We describe here a computational model based upon the temporal characteristics of the information in the auditory nerve-fiber firing patterns. The model produces a frequency domain representation of the input signal in terms of the ensemble histogram of the inverse of the interspike intervals, measured from firing patterns generated by a simulated nerve-fiber array. The nerve-fiber mechanism is modeled by a multi-level-crossing detector at the output of each cochlear filter. We use 85 cochlear filters, equally spaced on a log-frequency scale from 200 Hz to 3200 Hz, and the level crossings are measured at positive threshold levels which are uniformly distributed in log scale. The resulting Ensemble Interval Histogram (EIH) pseudo spectrum shares two main properties: (1) fine spectral details are well preserved in the low-frequency region but become fuzzy at the high-frequency end; (2) the EIH spectrum is more robust in noise, compared with the traditional Fourier spectrum. This representation of the speech has been used as a front-end to a Dynamic Time Warping (DTW), speaker-dependent, isolated word recognizer. The database consisted of a 39-word alpha-digits vocabulary spoken by two male and two female speakers, in different levels of additive white noise. In the noise-free case, the performance of the EIH-based front-end is comparable to a conventional Fourier Transform (FFT)-based front-end. In the presence of noise, however, the EIH-based front-end is more robust. Compared with the FFT-based front-end, with increasing noise the recognition scores drop more slowly, the resulting gap increases as the SNR values decreases. Quantitatively, with the EIH-based front-end the recognizer achieves a given recognition score with global-SNR values which are between 5 dB and 15 dB lower.     

First Hungarian experiences with positron emission tomography (PET) studies. Members of the PET working group

Diagnostic investigations commenced on the 28th of June 1994 in Hungary's and Central Europe's first PET Centre at the University Medical School of Debrecen. The Centre is equipped with a GE 4096 Plus whole body PET scanner. A metabolic tracer, 18F-deoxy-D-glucose (FDG), was used in the investigations. During the first 15 months 249 PET investigations were made in the Centre of which 242 were diagnostic and 7 normal subjects served as control for the patient studies with brain scans. The number of oncological indications (intra- and extracranial tumours, Hodgkin's lymphomas) was n = 105 (43.4% of the 242 diagnostic examinations), neurological investigations (without intracranial tumours) formed the dominant group (n = 117; 48.3%), whereas the number of cardiological indications was 20 (8.3%). The oncological studies included those of intracranial tumours (n = 76; 31.4%); thyroid tumours (n = 9; 3.7%); Hodgkin's lymphomas (n = 7; 2.9%) and other extracranial tumours (n = 13; 5.4%). The distribution of different neurological and psychiatric investigations was as follows: localization of focal epileptogen zone (n = 60; 24.8%); differential diagnosis of dementias (n = 30; 12.4%); exploration of cerebrovascular diseases (n = 10; 4.1%); and other neurological diseases (n = 17; 7.0%). The main objective of the cardiological PET investigations was the exploration of viable myocardium. The present paper overviews both the procedures (including administrative issues, as well) and the results of the first 249 FDG-PET investigations.