Experimental investigation on the breakage of hard rock by the PDC cutters with combined action modes

To verify the feasibility and efficiency of rotary-percussive drilling assisted by waterjets in very hard rocks, experiments on the performance of polycrystalline diamond compact (PDC) cutters resisting different combined loads of static thrust, impact, cutting and waterjets on Missouri red granite and Halston limestone were investigated. The experiments were conducted by means of a drop hammer and linear cutting-impact table. The effects of static thrust (WOB), impact energy, impact spacing and waterjets on the rate of penetration in hard rocks are described and the results are analyzed by measuring the depth of the craters or cuts penetrated by PDC cutters. Results from the study confirmed that the combined mode of cutting-impact is very effective in very hard rocks.     

A Windows computer application for long term data acquisition, storage and presentation of biological signals

We developed a windows application dedicated to recording, displaying and storing large amounts of biological signals on a standard PC. The application works in Matlab and uses an A/D-converter interface that enables a user to run the same software for signal acquisition, display and processing with different A/D-converter boards. The software program consists of three integrated modules, for setting the protocol for signal acquisition; for commands that can be accessed during data acquisition and for software routines that enable off-line viewing, pre-processing and processing of recorded data. It adapts to different computer hardware configurations by enabling the user to define file size, data resolution and file storage on local and network hard disks during signal acquisition.     

Static analysis of orthotropic curved bridge decks

The static analysis of orthotropic curved bridge decks with two radial edges simply supported and other two curved edges free are analysed, using a combination of Fourier series and finite difference technique. The governing fourth order partial differential equation of orthotropic plates in polar co-ordinates is first converted to an ordinary differential equation and subsequently solved by finite difference method. In order to estimate the accuracy and reliability of the present formulation an example of curved plate is solved and the results are compared with the existing solutions.     

Activity of Brassica oleracea leaf juice on foodborne pathogenic bacteria

Many vegetables of the Cruciferae family have been found to possess antimicrobial properties against several microorganisms of clinical importance. In this study, we reported the antibacterial effect of Brassica oleracea juice on several food-borne pathogens. The juice was found to be effective in inhibiting the growth of Salmonella Enteritidis, verotoxigenic Escherichia coli O157:H7, E. coli HB producing thermolabile toxin, nontoxigenic E. coli, and Listeria monocytogenes, but not Enterococcus faecalis. All cauliflower cultivars tested suppressed bacterial growth in a dose-dependent manner after 5 h of treatments, and the reduction in the number of viable cells ranged from 1 log with a 10% juice concentration to more than 3 log with a 20% juice concentration. The foodborne bacteria tested were also markedly reduced by isothiocyanates, natural components abundant in the genus Brassica, indicating that glucosinolate-derived isothiocyanates can play a major role in the antimicrobial activity of cauliflower. The antimicrobial effect of juice was reduced in presence of cysteine, suggesting that one mechanism of action of the juice involves blocking bacterial sulfhydryl groups.     

Genetic algorithms for optimality of data hiding in digital images

This paper investigates the scope of usage of Genetic Algorithms (GA) for data hiding in digital images. The tool has been explored in this topic of research to achieve an optimal solution in multidimensional nonlinear problem of conflicting nature that exists among imperceptibility, robustness, security and payload capacity. Two spatial domain data hiding methods are proposed where GA is used separately for (i) improvement in detection and (ii) optimal imperceptibility of hidden data in digital images respectively. In the first method, GA is used to achieve a set of parameter values (used as Key) to represent optimally the derived watermark in the form of approximate difference signal used for embedding. In the second method, GA is used for finding out values of parameters, namely reference amplitude (A) and modulation index (μ) both with linear and non linear transformation functions, for achieving the optimal data imperceptibility. Results on robustness for both the methods against linear, non linear filtering, noise addition, and lossy compression as well as statistical invisibility of the hidden data are reported here for some benchmark images.     

Physical Modeling of Fast p-i-n Diodes With Carrier Lifetime Zoning, Part I: Device Model

This paper presents the development and implementation of a physics-based diode model which can simulate aspects of high-voltage diodes such as snappy recovery during punch-through and the modified carrier density profile due to local lifetime control. It uses a Fourier series solution for the ambipolar diffusion equation in the lightly doped base region. The model is compared with finite-element device simulations. A parameter extraction procedure for the diode with lifetime control is proposed in Part II.     

Crystal Structures,Thermogravimetric and Magnetic Properties of Four Organodiamine Templated Vanadium Oxide Frameworks: Influences of Diaminoalkane Templates

Absract A series of four diaminoalkane templated vanadium oxide polymeric frameworks, [V₂^IVO₈V₂^VO₂](C₂H₁₀N₂), [V₂^IVO₈V₂^VO₂](C₃H₁₂N₂), [V₄^IVO₁₀V₂^VO₄](C₄H₁₄N₂) and [V₄^IVO₁₀V₂^VO₄](C₅H₁₆N₂), have been successfully prepared under hydrothermal conditions. The crystal structures are fully characterized revealing layered structures composed of common inorganic building units, namely {V^IVO₅} square pyramids and {V^VO₄} tetrahedra. The layer registries are different depending on the molecular structure of the diaminoalkanes, and can be accounted for by the organic-inorganic interface interactions. The analysis of hydrogen bonds indicates their important role in directing two- and three-dimensional structural architectures. The influences of different diaminoalkanes are also apparent in both thermogravimetric and complex magnetic behaviors, and are discussed in details.     

A multifrequency algorithm for the retrieval of soil moisture on alarge scale using microwave data from SMMR and SSM/I satellites

The sensitivity of microwave emission at different frequencies to soil moisture in bare and vegetated soils has been investigated using experimental data. Since the best frequency for the measurement of soil moisture (L-band) is absent in current satellite sensors, it is necessary to seek alternative solutions. An algorithm is proposed for the retrieval of soil moisture based on the sensitivity to moisture of both the brightness temperature and the polarization index at C-band, one that is able to correct for the effect of vegetation by means of the polarization index at X-band. The algorithm has been tested by using experimental data collected with airborne microwave radiometers on agricultural areas and validated by using the data sets of special sensor microwave/imager (SMM/I) and scanning multichannel microwave radiometer (SMMR). These research activities are planned in view of coming new satellites: AQUA (NASA) and ADEOS-II (NASDA), which will be launched by the end of 2001. These will have new generation microwave radiometers (AMSR-E and AMSR) onboard, which show much better characteristics with respect to the previous sensors, in particular an enhanced spatial resolution     

Optimized Spread Spectrum Watermarking for Fading-Like Collusion Attack with Improved Detection Performance

This paper proposes an optimized spread spectrum image watermarking scheme robust against fading-like collusion attack using genetic algorithms (GA) in multiband (M-band) wavelet decomposition. M-band decomposition of host data offers advantages in better scale-space tiling and good energy compactness. This makes watermarking robust against frequency selective fading-like attack gain. On the other hand, GA would determine a threshold value for the selection of host coefficients (process gain i.e. the length of spreading code) used in watermark casting along with the respective embedding strengths. We then consider colluder (random gain) identification as multiuser detection problem and use successive interference cancelation (SIC) to accurately detect weak (low gain) colluder and innocent users too. A weighted correlator is developed first where weight factors are calculated through training/learning using a neural network. A closed mathematical form of joint probability of error is developed with the objective of minimizing the probability of false detection i.e. a colluder is identified as an innocent user and an innocent user is identified as a colluder, for a set of colluders involved. Simulation results show the relative performance gain of the weighted correlator and SIC scheme compared to the existing works.     

An image-in-image communication scheme using secret sharing and M-ary spread spectrum watermarking

Microsystem Technologies - Secret image sharing is a means of secure transmission of images on an open network through meaningful share generation that reduces suspiciousness of conventional image...