A simplified cell for triaxial testing of soil samples has been developed. The apparatus allows the initial volume of the sample and the changes in volume that take place during both hydrostatic and ...triaxial compression tests to be measured, with an accuracy of 0.1
cm
3. All samples prepared have been obtained and precompacted using a standardized procedure and the results plotted in diagrams. Thus, the behaviour of agricultural soil and how it reacts to principal stress could be determined. The results of triaxial tests on different samples, specifically prepared with loose sandy soil of given composition and water content, using the simplified apparatus, are examined. The equipment was not expensive and easy to use and it also had the same degree of accuracy as other commercially available equipment.
An implementation of Central Force Optimization (CFO) utilizing variable initial probes and decision space adaptation is presented. The algorithm is tested against a suite of benchmark functions and ...CFO’s results compared to those of other algorithms. CFO performs well against the benchmarks, and also in scalability tests in 300-dimensions.
The objective of this investigation was to study and simulate the plough mouldboard soil interaction phenomena. A numerical simulation of the interaction between the soil and the plough mouldboard ...was performed by utilising the ‘finite volumes’ numerical approach. Simulation was carried out by utilising a three-dimensional free-surface model as well as a soil medium with the constitutive relationship of a non-Newtonian pseudo-plastic material. Such a ‘virtual’ material could properly simulate the global effects of the plough mouldboard – soil interaction of the test soil (sandy loam). Field tests were performed to validate the model using piezo-resistive transducers to detect the normal stresses on 14 points located on the working surface of a plough mouldboard. The stress distribution was then derived by using spatial interpolation and the results compared with the numerical simulation data. The maximum error detected by comparing numerical results with the experimental data set was less than 10%.
Various intragastric balloons have been used in obese patients for temporary weight loss. Recently, a new balloon, the Heliosphere Bag, was proposed. In a preliminary study, we evaluated the safety ...and efficacy of this device.
The Heliosphere Bag was used in 10 patients, selected according to the guidelines for obesity surgery. The manufacturer's instructions were followed in positioning the device. Heliosphere Bag positioning was performed, after diagnostic endoscopy, under unconscious sedation. After placement, the balloon was slowly inflated with 840-960 cc of air, which gives the inflated final volume of 650-700 cc of air, as the air is compressed. On the first and second post-treatment day, intravenous saline (30-35 ml/kg/d) with omeprazole (20 mg/d), ondansetron (8 mg/d) and butylscopolamine bromide (20 mg t.i.d.) were given to all patients. All patients from day 3 after placement began liquid diet and were discharged home on day 4 on a 1000 kcal diet (carbohydrate 146 g, lipid 68 g, protein 1 g/kg ideal weight). After 6 months, the Heliosphere Bag was removed. The patients were followed monthly, and complications and their treatment, post-placement symptoms, BMI and %EWL were recorded. Data were expressed as mean +/- SD.
From Sept-Dec 2004, 10 patients (5M/5F) underwent Heliosphere Bag placement, with age 35.2 +/- 15.7 years (17-49), BMI 43.3 +/- 8.1 kg/m(2) (35-51.2), and weight 126.8 +/- 23.7 kg (98.4-148). Heliosphere Bag positioning was quite difficult in all patients due to low pliancy and large size of the bag, causing patient discomfort. System failure at time of Heliosphere Bag positioning was observed in 5/10 patients (50%). At time of removal, the Heliosphere Bag was not found in the stomach in one patient. In 3 other patients, the balloon was found partially deflated. At the time of balloon removal after 6 months, BMI was 37.4 +/- 13.4 (28.9-42.1) and %EWL was 29.1 +/- 20.1 (9.0-57.4). BMI loss was 5.2 +/- 13.1 (1.9-11.2) and mean weight loss was 17.5 +/- 16.2 kg (5-33).
Although weight loss was satisfactory, this device cannot be considered an advance for the temporary treatment of morbid obesity. This balloon still has some instrumental and technical problems that need to be solved: high rate of system failure at positioning, high rate of spontaneous deflation, absence of a marker such as methylene blue, and large size with low pliability that cause significant patient discomfort.
This paper presents extended artificial physics optimization (EAPO), a population-based, stochastic, evolutionary algorithm (EA) for multidimensional search and optimization. EAPO extends the ...physicomimetics-based Artificial Physics Optimization (APO) algorithm by including each individual’s best fitness history. Including the history improves EAPO’s search capability compared to APO. EAPO and APO invoke a gravitational metaphor in which the force of gravity may be attractive or repulsive, the aggregate effect of which is to move individuals toward local and global optima. A proof of convergence is presented that reveals the conditions under which EAPO is guaranteed to converge. Discrete-time linear system theory is used to develop a second-order difference equation for an individual’s stochastic position vector as a function of time step. Stable solutions require eigenvalues inside the unit circle, leading to explicit convergence criteria relating the run parameters {
m
i
,
w,
G}. EAPO is tested against several benchmark functions with excellent results. The algorithm converges more quickly than APO and with better diversity.
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