Lime requirement studies on selected soils

It is recognized that there are important relationships of lime to soil fertility and crop production and that soils differ in related chemical and physical properties. Recommendations for applications of lime in Tennessee are made for both field and horticultural crops on soils of widely differing properties including differences in parent material, texture, humus content, and clay mineral type. At present, state recommendations for applications of lime are made largely on a basis of pH of the surface soil alone without considering texture, organic matter content, or other soil properties. A rule of thumb is used to recommend 2 tons of ground limestone per acre for each pH unit increase desired. This system includes a lime factor of about 2, recommending twice the required amount of calcium carbonate to compensate for coarseness, mixing, time required for reaction, and other factors which would limit the completeness of the reaction. In the future some soils not now used may be needed for agricultural production, or a more intensive management may be required on many soils than is now practiced. Either situation would tend to require a more precise system of making lime recommendations. The present distribution of soil samples may not represent all the soil conditions of the state, or the degree their future use might indicate. Some reports indicate that following present recommendations does not accomplish the pH adjustment desired. Liming recommendations should give some consideration to the sub-surface layers of soils within the rooting depths of commonly grown crops. These possibilities coupled with the considerable differences among soils indicate the desirability of a study of the surface and sub-surface layers of certain differing soils with respect to characteristics affecting lime relationships

Idealization in Scientific Explanation

Many phenomena pose interesting “fundamental” questions for both physics and philosophy of science. Understanding and explanation often seem to require non-Galilean, essential idealizations. But idealizations are false. This fact suggests that we need to give up on the view that truth is a necessary condition for explanation

Displacement sensing using bi-modal resonance in over-coupled inductors

This paper presents the theory and key experimental findings for an investigation into the generation of bimodal resonance (frequency splitting) phenomena in mutually over-coupled inductive sensors, and its exploitation to evaluate relative separation and angular displacement between coils. This innovative measurement technique explores the bimodal resonant phenomena observed between two coil designs - solenoid and planar coil geometries. The proposed sensors are evaluated against first-order analytical functions and finite element models, before experimentally validating the predicted phenomenon for the different sensor configurations. The simulated and experimental results show excellent agreement and first-order best-fit functions are employed to predict displacement variables experimentally. Co-planar separation and angular displacement are shown to be experimentally predictable to within $\pm1mm$ and $\pm1^o$ using this approach. This study validates the first-order physics-based models employed, and demonstrates the first proof-of-principle for using resonant phenomena in inductive array sensors for evaluating relative displacement between array elements

Deterministic epidemic models overestimate the basic reproduction number of observed outbreaks

The basic reproduction number, $R_0$, is a well-known quantifier of epidemic spread. However, a class of existing methods for estimating this quantity from epidemic incidence data can lead to an over-estimation of this quantity. In particular, when fitting deterministic models to estimate the rate of spread, we do not account for the stochastic nature of epidemics and that, given the same system, some outbreaks may lead to epidemics and some may not. Typically, an observed epidemic that we wish to control is a major outbreak. This amounts to implicit selection for major outbreaks which leads to the over-estimation problem. We show that by conditioning a `deterministic' model on major outbreaks, we can more reliably estimate the basic reproduction number from an observed epidemic trajectory

Displacement sensing using bi-modal resonance in over-coupled inductors

This paper presents the theory and key experimental findings for an investigation into the generation of bimodal resonance (frequency splitting) phenomena in mutually over-coupled inductive sensors, and its exploitation to evaluate relative separation and angular displacement between coils. This innovative measurement technique explores the bimodal resonant phenomena observed between two coil designs - solenoid and planar coil geometries. The proposed sensors are evaluated against first-order analytical functions and finite element models, before experimentally validating the predicted phenomenon for the different sensor configurations. The simulated and experimental results show excellent agreement and first-order best-fit functions are employed to predict displacement variables experimentally. Co-planar separation and angular displacement are shown to be experimentally predictable to within $\pm1mm$ and $\pm1^o$ using this approach. This study validates the first-order physics-based models employed, and demonstrates the first proof-of-principle for using resonant phenomena in inductive array sensors for evaluating relative displacement between array elements

Development of a 1 kW, 200 C Mapham Inventor

Electronic systems and components are often exposed to high temperature environment in space-based applications, nuclear power facilities, and geothermal energy extraction fields. A key requirement for these systems is, therefore, to withstand the high temperature exposure while maintaining efficient and reliable operation. Efforts were taken to design and develop a high temperature power inverter capable of 200 C operation. A 1 kW, 20 kHz Mapham inverter was designed and evaluated as a function of temperature at different load levels. The inverter system, excluding its input, control, and logic circuits, was characterized at temperatures from ambient to 200 C at 0%, 50%, and 100% resistive loading. With an applied input voltage of 75 VDC, the inverter produced an output of 250 VAC. The results obtained, which indicate good operational characteristics of the inverter up to 200 C, are presented and discussed