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91.
The similarity between two nuclear systems is expressed by the representativity factors and maximizing its value to unity reduces the uncertainty from its existing value. As the representativity factor is a function of covariance matrix of neutron cross-sections, the inherent systematic uncertainty in neutron cross-sections inhibits it from approaching unity and hence statistical procedures have to be resorted to minimize the systematic uncertainty. As the conventional statistical techniques fail when systematic uncertainty is dominant, we propose an entropy based information theoretic approach of maximizing the mutual information by the knowledge of bounds for the correlated elements. We show that maximizing the mutual information and the representativity factors express the similar phenomena of uncertainty reduction. We estimated the bounds for the correlated elements of the correlation matrix for minor actinides and show how the systematic uncertainty is reduced when lower bound values are considered. These lower bound values aid in experimental planning for future measurement of cross-sections with reduced systematic uncertainty. 相似文献
92.
Kattel K Park JY Xu W Kim HG Lee EJ Bony BA Heo WC Lee JJ Jin S Baeck JS Chang Y Kim TJ Bae JE Chae KS Lee GH 《ACS applied materials & interfaces》2011,3(9):3325-3334
A facile one-pot synthesis of d-glucuronic acid-coated ultrasmall Ln(2)O(3) (Ln = Eu, Gd, Dy, Ho, and Er) nanoparticles is presented. Their water proton relaxivities were studied to address their possibility as a new potential MRI contrast agent. We focused on the d-glucuronic acid-coated ultrasmall Dy(2)O(3) nanoparticle because it showed the highest r(2) relaxivity among studied nanoparticles. Its performance as a T(2) MRI contrast agent was for the first time proved in vivo through its 3 T T(2) MR images of a mouse, showing that it can be further exploited for the rational design of a new T(2) MRI contrast agent at high MR fields. 相似文献
93.
Konapala Sambasiva Rao Dasari Madhava Prasad Prayaga Murali Krishna B. Hima Bindu K. Suneetha 《Journal of Materials Science》2007,42(17):7363-7374
Barium strontium gadolinium bismuth niobate (Ba0.1Sr0.81Gd0.06Bi2Nb2O9, BSGBN) ceramics were prepared by using the conventional solid-state reaction method. The dielectric permittivity, modulus and impedance spectroscopy studies on BSGBN were investigated in the frequency range, 45 Hz–5 MHz and in the temperature range from room temperature (RT) to 570 °C. The dielectric anomaly with a broad peak was observed at 470 °C. Simultaneous substitution of Ba2+ and Gd3+ increases the transition temperature of SrBi2Nb2O9 (SBN) from 392 to 470 °C. XRD studies in BSGBN revealed an orthorhombic structure with lattice parameters a = 5.4959 Å, b/a = 1.000, c = 25.0954 Å. Impedance and modulus plots were used as tools to analyse the sample behaviour as a function of frequency. Cole-Cole plots showed a non-Debye relaxation. Also, dc and ac conductivity measurements were performed on BSGBN. The electric impedance which describes the dielectric relaxation behaviour is fitted to the Kohlrausch exponential function. Near the phase transition temperature, a stretched exponential parameter β indicating the degree of distribution of the relaxation time has a small value. 相似文献
94.
No doubt that chlorination has been successfully used for the control of water borne infections diseases for more than a century. However identification of chlorination byproducts (CBPs) and incidences of potential health hazards created a major issue on the balancing of the toxicodynamics of the chemical species and risk from pathogenic microbes in the supply of drinking water. There have been epidemiological evidences of close relationship between its exposure and adverse outcomes particularly the cancers of vital organs in human beings. Halogenated trihalomethanes (THMs) and haloacetic acids (HAAs) are two major classes of disinfection byproducts (DBPs) commonly found in waters disinfected with chlorine. The total concentration of trihalomethanes and the formation of individual THM species in chlorinated water strongly depend on the composition of the raw water, on operational parameters and on the occurrence of residual chlorine in the distribution system. Attempts have been made to develop predictive models to establish the production and kinetics of THM formations. These models may be useful for operational purposes during water treatment and water quality management. It is also suggested to explore some biomarkers for determination of DBP production. Various methods have been suggested which include adsorption on activated carbons, coagulation with polymer, alum, lime or iron, sulfates, ion exchange and membrane process for the removal of DBPs. Thus in order to reduce the public health risk from these toxic compounds regulation must be inforced for the implementation of guideline values to lower the allowable concentrations or exposure. 相似文献
95.
Digital speckle photography combined with TV shearography is developed for precise measurement of the magnitude of the shear field in a linear shear configuration. As an application the method is implemented to determine the slope-change variations of a three-dimensional object with TV shearography in which the shear magnitude is obtained with the digital speckle photography technique. 相似文献
96.
Krishna C. Mandal Sung Hoon Kang Michael Choi Job Bello Lili Zheng Hui Zhang Michael Groza Utpal N. Roy Arnold Burger Gerald E. Jellison David E. Holcomb Gomez W. Wright Joseph A. Williams 《Journal of Electronic Materials》2006,35(6):1251-1256
High-quality, large (10 cm long and 2.5 cm diameter), nuclear spectrometer grade Cd0.9Zn0.1Te (CZT) single crystals have been grown by a controlled vertical Bridgman technique using in-house zone refined precursor
materials (Cd, Zn, and Te). A state-of-the-art computer model, multizone adaptive scheme for transport and phase-change processes
(MASTRAP), is used to model heat and mass transfer in the Bridgman growth system and to predict the stress distribution in
the as-grown CZT crystal and optimize the thermal profile. The model accounts for heat transfer in the multiphase system,
convection in the melt, and interface dynamics. The grown semi-insulating (SI) CZT crystals have demonstrated promising results
for high-resolution room-temperature radiation detectors due to their high dark resistivity (ρ≈2.8 × 1011 Θ cm), good charge-transport properties [electron and hole mobility-life-time product, μτe≈(2–5)×10−3 and μτh≈(3–5)×10−5 respectively, and low cost of production. Spectroscopic ellipsometry and optical transmission measurements were carried out
on the grown CZT crystals using two-modulator generalized ellipsometry (2-MGE). The refractive index n and extinction coefficient
k were determined by mathematically eliminating the ∼3-nm surface roughness layer. Nuclear detection measurements on the single-element
CZT detectors with 241Am and 137Cs clearly detected 59.6 and 662 keV energies with energy resolution (FWHM) of 2.4 keV (4.0%) and 9.2 keV (1.4%), respectively. 相似文献
97.
Qian Liu Shohei Kumagai Sergei Manzhos Yingqian Chen Indunil Angunawela Masrur Morshed Nahid Krishna Feron Steven E. Bottle John Bell Harald Ade Jun Takeya Prashant Sonar 《Advanced functional materials》2020,30(34)
To achieve semiconducting materials with high electron mobility in organic field‐effect transistors (OFETs), low‐lying energy levels (the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO)) and favorable molecular packing and ordering are two crucial factors. Here, it is reported that the incorporation of pyridine and selenophene into the backbone of a diketopyrrolopyrrole (DPP)‐based copolymer produces a high‐electron‐mobility semiconductor, PDPPy‐Se. Compared with analogous polymers based on other DPP derivatives and selenophene, PDPPy‐Se features a lower LUMO that can decrease the electron transfer barrier for more effective electron injection, and simultaneously a lower HOMO that, however, can increase the hole transfer barrier to suppress the hole injection. Combined with thermal annealing at 240 °C for thin film morphology optimization to achieve large‐scale crystallite domains with tight molecular packing for effective charge transport along the conducting channel, OFET devices fabricated with PDPPy‐Se exhibit an n‐type‐dominant performance with an electron mobility (μe) as high as 2.22 cm2 V?1 s?1 and a hole/electron mobility ratio (μh/μe) of 0.26. Overall, this study demonstrates a simple yet effective approach to boost the electron mobility in organic transistors by synergistic use of pyridine and selenophene in the backbone of a DPP‐based copolymer. 相似文献
98.
Gilja V Chestek CA Diester I Henderson JM Deisseroth K Shenoy KV 《IEEE transactions on bio-medical engineering》2011,58(7):1891-1899
Neural prosthetic systems aim to help disabled patients by translating neural signals from the brain into control signals for guiding computer cursors, prosthetic arms, and other assistive devices. Intracortical electrode arrays measure action potentials and local field potentials from individual neurons, or small populations of neurons, in the motor cortices and can provide considerable information for controlling prostheses. Despite several compelling proof-of-concept laboratory animal experiments and an initial human clinical trial, at least three key challenges remain which, if left unaddressed, may hamper the translation of these systems into widespread clinical use. We review these challenges: achieving able-bodied levels of performance across tasks and across environments, achieving robustness across multiple decades, and restoring able-bodied quality proprioception and somatosensation. We also describe some emerging opportunities for meeting these challenges. If these challenges can be largely or fully met, intracortically based neural prostheses may achieve true clinical viability and help increasing numbers of disabled patients. 相似文献
99.
Krishna Kanta Panthi Bjørn Nilsen 《Bulletin of Engineering Geology and the Environment》2006,65(1):57-63
Numerical modelling has been used for analyzing stresses and displacements for the very steep and more than 1,000 m high Heggura rock slope near Tafjord, Norway where a disastrous 3 million m3 rock slide occurred in 1934. It is shown that very anisotropic stresses exist near the slope surface and displacements of the remaining slope as result of the 1934 slide have been calculated to up to 210 mm. Such considerable displacements are believed to have a significant impact on the present and future stability of the Heggura slope. 相似文献
100.
Krishna Kanwar Bhati K.M. Gangotri 《International Journal of Electrical Power & Energy Systems》2011,33(2):155-158
Photogalvanic cells having different surfactants, reductants and photosensitizers have been tried to get the better electrical output and storage capacity. Through literature survey shows that system having NaLS as a surfactant, xylose as a reductant and methylene blue as a photosensitizer has not been explored to get the required results and achievements so the efforts have been made by the system in photogalvanic cell to get better electrical output (i.e. photopotential 834 mV, photocurrent 90 μA, power and power at power point are 75.06 μW and 32.72 μW) and also good storage capacity i.e. 55 min in dark. The observed conversion efficiency and fill factor for this is 0.31%, 0.363%. The effect of different parameter like pH, diffusion length on electrical output of the cell was also studied and tentative mechanism for the generation of photocurrent was also purposed. 相似文献