Robust estimation in flat fading channels under bounded channel uncertainties

We investigate channel equalization problem for time-varying flat fading channels under bounded channel uncertainties. We analyze three robust methods to estimate an unknown signal transmitted through a time-varying flat fading channel. These methods are based on minimizing certain mean-square error criteria that incorporate the channel uncertainties into their problem formulations instead of directly using the inaccurate channel information that is available. We present closed-form solutions to the channel equalization problems for each method and for both zero mean and nonzero mean signals. We illustrate the performances of the equalization methods through simulations.     

Use of ozone in detoxification of aflatoxin B1 in red pepper

Red pepper (Capsicum annuum) is one of the most important agricultural products of Turkey. For public health and export requirements, red pepper must be produced free of hazardous contaminants. However, previous investigations showed that red pepper could be contaminated by aflatoxin above the limits that may be critical for health. In this study, use of the high oxidising power of ozone achieved detoxification of aflatoxin. Samples were subjected to ozonation at various ozone concentrations (16, 33, 66 mg/l) and exposure times (7.5, 15, 30, 60 min). In summary, the reductions of content of aflatoxin B₁ in flaked and chopped red peppers were 80% and 93% after exposures to 33 mg/l ozone and 66 mg/l ozone for 60 min, respectively.     

A PML using a convolutional curl operator and a numerical reflection coefficient for general linear media

A general time domain representation of the Chew and Weedon [1994] stretched coordinate perfectly matched layer (PML) absorbing boundary condition is described. This new approach mathematically operates on the spatial field derivatives and allows the PML update equations to be trivially derived from any set of general linear medium update equations. A method for calculating the frequency dependent reflection coefficient for this form of the PML is derived for general linear media. Two and three dimensional numerical test results, which validate the calculation of the reflection coefficient, are presented. The range of numerical tests include the PML matching of free space, a magnetoplasma, and a free space waveguide. Improving the reflection coefficient is examined.     

ULF/ELF electromagnetic fields produced in a conducting medium of infinite extent by a linear current source of finite length

A linear current source of finite length embedded in a conducting medium of infinite extent is considered. Assuming a sea-water medium, the components of the electric and magnetic fields are numerically evaluated for two frequencies in the ULF/ELF range (frequencies less than 3 kHz). Comparison is made between the electric field vectors produced at the two different frequencies, and curves are plotted for one of the frequencies showing the variation with distance of the amplitudes of the electric and magnetic field components. A parametric approach is outlined that generalizes the field data presented in the figures and which enables the data to be extended to conducting media other than sea water and to other frequencies in the ULF/ELF range. Some practical applications of the data are discussed.     

Determination of optimal EDM machining parameters for machined pure titanium-porcelain adhesion

The objective of this experimental study is to determine electrical discharge machining (EDM) parameters that offer the best adhesion at the interface of a machined titanium–porcelain composite. First of all, with Taguchi method, machining parameters that will be effective in the bonding strength as well as their interactions on each other were determined in the test. Then, multiple level experiments were conducted to determine how the effective parameters varied over a wide area. Slopes of the curves obtained in these tests were studied, and then, final tests were conducted to obtain the best bonding strength possible. In this way, machining parameters that would offer the highest bonding strength of the titanium–porcelain matrix in a stepwise adjustable EDM machine were obtained. By taking into consideration the steps on the EDM machine where the tests were conducted, it is seen that, when a full factorial experiment is undertaken, 5 power?×?2 polarity?×?2 type of dielectric?×?2 sandblasting or non-sandblasting?×?2 kind of electrode?×?10 pulse-on time, it necessitates 800 different tests to be executed, but, with the applied method, 16?+?18?+?3 yields 37 different tests where the results that include all possible alternatives were obtained. As a result, EDM machining parameters that offer the highest adhesion and are relatively higher, 31.5 N/mm², than the acceptable minimum value of 25 N/mm² were specified.     

A hybrid breast cancer detection system via neural network and feature selection based on SBS, SFS and PCA

Two hybrid feature selection methods (SFSP and SBSP) which are composed by combining the sequential forward selection and the sequential backward selection together with the principal component analysis developed by utilizing quadratic discriminant analysis classification algorithmic criteria so as to utilize in the diagnosis of breast cancer fast and effectively are presented in this study. The tenfold cross-validation method has been applied in the algorithm, which is utilized as criteria during the selection of the features. The dimension of the feature space for input has been decreased from 9 to 4 thanks to the selection of these two hybrid features. The Artificial Neural Networks have been used as classifier. The cross-validation method has been preferred also in the phase of this classification as in the case of the selection of the feature in order to increase the reliability of the result. The Wisconsin Breast Cancer Database obtained from the UCI has been utilized so as to determine the correctness of the system suggested. The values of the average correctness of the classification obtained by utilizing a tenfold cross-validation of the two hybrid systems developed earlier are found, respectively, as follows: for SFSP + NN, 97.57 % and for SBSP + NN, 98.57 %. SBSP + NN system has been observed that, among the studies carried out by implementing the cross-validation method for the breast cancer, the result appears to be very promising. The acquired results have revealed that this hybrid system applied by means of reducing dimension is an utilizable system in order to diagnose the diseases faster and more successfully.     

Special singularity integral identity and its applications in electrical circuits

A new special singularity integral identity involving the product of the impulse symbol and the unit step function is proposed. A proof of this integral identity is provided followed by its application in the solution of a simple well-known ideal example problem in electrical circuits.