Wide Range Of Laboratory Data Research Articles

Apparent friction coefficient in straight compound channels

In compound open channel flow, the strong interaction between the main channel and the shallow floodplains affects considerably the discharge capacity. Since this phenomenon was identified, many authors have estimated experimentally the flow interaction in terms of an apparent shear stress acting at the vertical interface between the main channel and the floodplains. Empirical formulae have been developed to quantify this apparent shear stress, yet without general applicability. Herein, a dimensionally sound expression, depending on the square of the velocity gradient between the main channel and the floodplains, and on the so called “apparent friction coefficient”, is proposed. Its variation with the geometrical and roughness ratios is analysed herein. A generalized formulation to predict the apparent shear stress is presented and validated for a wide range of laboratory data. These include small-scale flumes and the large-scale flood channel facility, with both smooth and rough floodplains.

Study on The Angle of Repose of Nonuniform Sediment

A conception of exposure degree is used in this article to account for the hiding and exposure mechanism of nonuniform sediment transport. The force arms of particles on the bed slope are assumed to be a function of the exposure degree, which is stochastically related to the size and gradation of bed materials. Based on this conception, the formula for the angle of repose of nonuniform sediment is developed. The angle of repose of nonuniform sediment is experimentally investigated in rotation drum at the rolling motion of sediment particles. The nonuniform sediment is gotten from the mixture of two kinds of uniform sediment with different weight ratios and two experimental plans that one for changing the weight ratio of two kinds of uniform sediment from 1:9 to 9:1 and the other changing the uniform sediment size and weight ratio are used. The effect of the rotation speed and the filling degree on the angle of repose is investigated, too. Finally, the formula has been tested against a wide range of laboratory data, the prediction by the newly proposed formulas is very good.

G-CSF treatment of canine cyclical neutropenia: A comprehensive mathematical model

To study the effects of different G-CSF temporal treatment schemes using a comprehensive mathematical model of the mammalian hematopoietic system that couples the pharmacokinetics of granulocyte colony-stimulating factor (G-CSF) to the hematopoietic stem cell, neutrophil, platelet, and erythrocyte dynamics. Data from cyclical neutropenic (CN) grey collies are used to build an extended model that reproduces the dynamics of circulating blood cells found in laboratory data from the dogs with and without daily G-CSF therapy. The effects of varying the treatment initiation time, and whether injections are given daily, every other day, or every three days, are examined. The mathematical model is able to reproduce the large variation in data that occurs from one dog to another. Different drug delivery times, with no other changes in the model parameters, can have significant long-term effects on neutrophil numbers. The frequency of drug delivery also has long-term effects on the oscillations. Using a realistic representation of the effects of G-CSF on the tissue-level hematopoietic system, the model matches a wide range of laboratory data. This implies that it would be possible to generate individualized predictions for specific dogs if data were available in real time. The proposed interventions are practical and may reduce the amount of G-CSF required while potentially maintaining or even improving the treatment effects.

Making contact to aged surfaces

A Monte Carlo analysis of aged crossed rod copper (Cu) contacts was conducted to evaluate the effects from a number of variables such as film thickness, contact force, microhardness and geometry. The analysis was conducted using two previously developed models that employ material properties and design parameters as constraints in a statistical model of degradation. It was shown, using a power law model to describe the surface concentration of oxides, that the degradation model could be calibrated to produce results that showed good agreement with a wide range of laboratory data. In addition it was found that the recently observed difference in performance of soft and hard Cu contacts could be explained within the framework of the degradation model. It was concluded that the mechanism which causes oxide accumulation in the surface layer is affected by microhardness in a way which is less favorable to the performance of soft Cu contacts. The reason for this type of behavior was not determined and warrants further investigation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Delayed linear growth in children with enterocystoplasties.

A series of 60 children whose urine was stored in pouches formed in whole or in part from bowel were reviewed to establish the effect on growth in height and weight. The mean age at operation was 7.8 years (range 0.9-14.1). Patients were included only if there were at least 2 measurements of both parameters pre-operatively and 2 post-operatively over a minimum follow-up of 2.5 years. Delayed growth in height alone occurred in 12 children (20%), with a mean loss of 25 percentile points (range 10-50). Delayed growth in height and weight occurred in 4. Accelerated growth in height alone, weight alone and in both occurred in 2, 7 and 7 respectively. There was no difference in a wide range of laboratory data between any of these groups. Although changes in growth rate (for better or worse) may occur for a variety of reasons after major surgery, delayed linear growth in isolation is an unusual and worrying finding that suggests a major alteration in bone development.

An advanced integral model for cooling tower plume dispersion

An advanced integral model is developed for predicting cooling tower plume rise from single natural draft cooling towers. The theoretical formulation of the model is aimed at avoiding many of the pitfalls and unnecessary assumptions of existing models. The model is based on a careful integration of the three-dimensional partial differential equations of conservation across the plume cross-section; radial profiles of temperature, velocity, and total water are assumed to be Gaussian in shape. The model includes a treatment of plume thermodynamics and tower downwash effects. The model has been calibrated with a wide range of laboratory data. Verification of the model with single-tower field data from Chalk Point, Paradise, Lünen, Gardanne and Philippsburg reveals good results.