Determination of multilayer soil parameters using Simulated Annealing algorithm
The paper presents a new method based on the Simulated Annealing Algorithm for the estimation of the parameters of multilayer soils. First the infinite integral of resistivity equation is approximated by use of complex image method. Then, Simulated Annealing Method is used to estimate the soil resistivity with the least error.
Parameter Estimation of Horizontal Multilayer Earth by Complex Image Method
How to correctly obtain the structure parameters of earth is the precondition of grounding system design. Based on the local searching algorithm, an efficient method for estimating earth structure with any number of layers from the test data by Wenner configuration method is presented. In each iterative procedure, earth apparent resistivities are calculated by complex image method. A new method to directly obtain the partial derivatives of the earth apparent resistivities with respect to the earth parameters from the results of the complex image method is presented, which is more efficient than the conventional methods that arduously calculate the improper integrals with a Bessel's function and an infinite limit of integration. At the same time, a method to determine suitable initial earth parameters for the local searching algorithm is also proposed. The validity of the method is shown by several applications.
The costs of identifying undiagnosed prostate cancer in asymptomatic men in New Zealand general practice
Background. Screening for prostate cancer (PCa) using the prostate-specific antigen (PSA) test is widespread in New Zealand. 3 informed testing history in 2007–09 were NZ$8887 compared to NZ$13 870 if the men had PSA tests in 2007–09. If we assumed a PSA test involved a full 15-minute general practice consultation, the estimated costs increased to NZ$26 877 per PCa identified. Conclusions. Screening of asymptomatic men for PCa is widely practiced. Most of the costs of screening were incurred in general practice. Calls for men to receive increased information on the harms and benefits of screening will substantially increase the costs. The current costs could be reduced by better targeting of screening.