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The containment of radionuclides over very long periods of time is based on the interposition of a multi-barrier system between the waste and the biosphere. A performance allocation study is usually conducted for each barrier. Each barrier is then designed, in terms of geometry and composition, to cope with the performance it has been allocated. However geochemical interactions will occur between the different barriers. An alkaline plume will be generated by cement materials, a redox front will be generated by container corrosion and geochemical gradients will be generated by the dissolution of artificial barriers by natural groundwater. Radionuclide retention mechanisms are strongly pH and Eh dependent, therefore the impact of these geochemical transients on retention must be quantitatively evaluated to check the performance of each barrier for realistic in-situ situations. To assess this impact, two types of engineered barriers (clay and cement) for a spent fuel repository are simulated with a coupled hydrogeochemical model. Comparisons between hydraulic heterogeneous (fractured) and simple homogeneous systems are also carried out in terms of waste dissolution.
In this paper, structural modelling and dynamic analysis methods reflecting the characteristics of a liquid propellant were developed for a pogo analysis. The pogo phenomenon results from the complex interaction between the vehicle structural vibration in the longitudinal direction and the propulsion system. Thus, for an accurate vibration analysis of a liquid propellant launch vehicle, both the consumption of the liquid propellant and the change in the stiffness reflecting the nonlinear hydroelastic effect were simultaneously considered. A complete vehicle structure, including the liquid propellant tanks, was analytically modelled while focusing on pogo. In addition, a feasible liquid propellant tank modelling method was established to obtain an one-dimensional complete vehicle model. With these methods, comparative studies of the hydroelastic effect were conducted. Evaluations of the dynamic analysis of a reference vehicle were also conducted during the first burning stage. The numerical results obtained with the present orthotropic model and the dynamic analysis method were found to be in good agreement with the natural vibration characteristics according to previous analyses and experiments. Additionally, the reference vehicle showed the estimated occurrence of pogo in the first structural mode when compared with the frequencies of the propellant feeding system. In conclusion, the present structural modelling and modal analysis procedures can be effectively used to analyse dynamic characteristics of liquid propellant launch vehicles. These techniques are also capable of identifying the occurrence of pogo and providing design criteria related to pogo instability.
The Korean native chicken (KNC) is believed to have existed in the Korean Peninsula more than 1,400 years ago. Since then, KNC have been bred only by private farmers in rural areas of Korea. In 1994, a KNC conservation program was established by the Korean government and, as a result, five lines were restored. KNC are considered to have a unique taste and texture that is more attractive to Korean consumers than meat from commercial broilers. However, the price of KNC is relatively high, which is mainly due to the breed's low growth rate, hence the limitations for industrial applications. In addition, their unique taste and texture in comparison with that of other broilers has been evaluated by scientists over the past few years. The general composition, physiochemical traits, content of taste-active and endogenous bioactive compounds and sensory quality of KNC meat, as well as breeding history are reviewed in this paper. The information from this review can be used for the development of commercial KNC breeds and can be applied to models for the commercialisation of native chicken breeds in developing countries.
A new approach is proposed to analyze Bremsstrahlung X-rays that are emitted from laser-produced plasmas (LPP) and are measured by a stack type spectrometer. This new method is based on a spectral tomographic reconstruction concept with the variational principle for optimization, without referring to the electron energy distribution of a plasma. This approach is applied to the analysis of some experimental data obtained at a few major laser facilities to demonstrate the applicability of the method. Slope temperatures of X-rays from LPP are determined with a two-temperature model, showing different spectral characteristics of X-rays depending on laser properties used in the experiments.
RZ Cas is an Algol-type eclipsing binary system where the primary component was recently discovered as a δ Set pulsator. A three-continent multisite photometric campaign was carried out during 1999. Preliminary results are reported here indicating a semi-detached system where the secondary fills its Roche lobe. The light curves also suggest a hot spot on the surface of the primary component as a consequence of the impact of the mass stream from the secondary. The pulsational behaviour can be well described with only one frequency.
Recent progress has been achieved in the identification of quantitative trait loci (QTLs) and candidate genes, and they have been found to be very important for the production of chickens with more desirable meat characteristics. The major economic traits of chicken meat production were divided into two major categories, namely growth and carcass condition. In this paper, the QTL locations and candidate genes for the above mentioned traits are reviewed. The results presented here will provide guidelines for the selection of high quality and highly productive chickens through the marker assisted selection (MAS), which should be extensively used by poultry breeders and companies.
Solid phase amorphization has been found to occur in all refractory metal and a number of rare—earth and platinum group metal thin film on silicon systems. For Ti/Si, Zr/Si, Hf/Si, V/Si, Nb/Si and Ta/Si systems, the growth of amorphous interlayer (a—interlayer) was found to follow a linear law in the initial stage. Si atom was found to be the dominant diffusing species in the solid phase amorphization in Ti/Si, Zr/Si and Hf/Si systems. For the Y/Si system, the stability of amorphous interlayer depends critically on the composition of the amorphous films.
Auto–correlation function analysis was utilized to determine the structure of the amorphous interlayers. HRTEM in conjunction with the fast Fourier transform were applied to determine the first nucleated crystalline phase. Simultaneous presence of multiphases was observed to occur in a number of refractory metal/Si systems. Interesting electrical properties of amorphous interlayers were found for Ti/Si, Zr/Si and Hf/Si systems.
When an elastic half-space is subjected to both normal and tangential contact, the ratio of normal and tangential contact stiffnesses can be measured by various scanning force microscopy techniques. For elastically isotropic solids, this stiffness ratio depends on Poisson’s ratio as given by the Mindlin solution. An anisotropic elastic contact analysis here shows the difference between the effective Poisson’s ratio as defined from the stiffness ratio and its uniaxial counterpart with respect to various crystal structures and various normal/tangential contact directions. Closed-form analytical solutions of effective indentation moduli are derived for materials with at least one plane of transverse isotropy. Since the Sneddon (normal contact) and Mindlin (lateral contact) solutions are derived under different frictional conditions, finite element simulations were performed which show that the effects of elastic dissimilarity and contact shape are generally small but not negligible. The predicted dependence on crystallographic orientation and elastic anisotropy has been compared favorably with previously reported multiaxial contact experiments for a number of cubic single crystals. Implications for atomic force microscopy based experiments are also discussed.
The study of dislocation nucleation has gained increasing attentions recently primarily due to the advancement of small scale mechanical testing methods. Based on the classic Rice model of dislocation nucleation from a crack tip in which the dislocation core is modeled by a continuous slip field, a nonlinear finite element method can be formulated with the interplanar potential as the input, and the development of interplanar slip field can be solved from the resulting boundary value problems. The effects of geometric boundary conditions, loading patterns, etc. can be conveniently determined, as opposed to the time consuming molecular simulations. To validate the method, we compare the simulations results of homogeneous dislocation nucleation and heterogeneous dislocation nucleation from a two-dimensional crack tip to the literature results. As proposed by Rice and Beltz (J. Mech. Phys. Solids, 1994), the activation energy for dislocation nucleation from a three-dimensional crack tip depends on the finite thickness in the direction parallel to the crack tip, which has been successfully reproduced in the finite element simulation results reported here.
The change in dielectric constant relaxation time over temperature (35–590 °C) and frequency (45 Hz–5 MHz) in ceramics of Pb0.77K0.115Gd0.115Nb2O6 (PKGN, Tc = 340 °c) has been studied. Powder X-ray diffraction revealed the single-phase formation with orthorhombic crystal structure. The P-E hysteresis loop parameters are Ps = 21.77 μC/cm2, Pr = 17.09 μC/cm2, Ec = 11.86 kV/cm; the piezoelectric constants, Kp = 31.7%, Kt = 47%, d33 = 115 × 10−12 C/N, d31 = −41 × 10−12 C/N, are determined in the material and some transducer applications are discussed. Cole-Cole (Zll vs. Zl) plots showed a non-Debye type relaxation. Conductivity obeyed Jonscher’s universal power law, σ = σ0 + Aωn. The theoretical values of εl and σ are computed using the parameters ‘A(T)’ and ‘n(T)’ (0 < n < 1) and are well fitted with the experimental data. The hopping ion frequency (ωp) and charge carrier concentration (Kl) have been analyzed using Almond-West formalism. The dielectric relaxation processes are associated with localized oxygen vacancies conduction at high frequency region. A long-range conductivity by Gd3+ ions is found to be predominant at low frequency region. The activation energies from impedance and modulus formalisms revealed the ionic type conduction in PKGN.
Limited research has been conducted to understand the relationship between heat wave warnings with public awareness and behavioral changes in the Asian population. The Hong Kong Observatory introduced the “very hot weather warning” in 2000 to alert the public of heatstroke and sunburn in Hong Kong. However, the population's behavioral responses to these weather alerts is unclear. Moreover, the relationship between perceived health risks and behavioral changes has not been examined. The goal of this study is to examine the health risk perceptions and behavioral changes following public heat wave warnings in Hong Kong.
A cross-sectional, population-based, telephone survey, using the last-birthday method was conducted within two weeks following a heat wave warning in 2009. A heat warning and a health study instrument, based on Intergovernmental Panel on Climate Change (IPCC) guidelines and related literature was developed and validated. Descriptive and multivariate logistic regression analyses were conducted.
The questionnaire was completed by 1,123 individuals whose socio-demographic characteristics were comparable to 2009 Hong Kong population census data. Of respondents, 83.6% were aware of the heat wave weather warning. Multivariate logistic regression of socio-demographic factors indicated that being female, those in middle age groups, and those with higher educational attainment was significantly associated with heat wave warning awareness. Among those aware of the public warning, the majority were unconcerned about potential adverse health effects, < 40% were aware of the community heat-related preparedness plans, and < 50% changed their behavior to mitigate the potential adverse health impacts of hot weather.
This is the first study to examine climate change and health behavioral responses in an urban Chinese population. Future research direction should further investigate correlations between awareness and health protective actions, as well as the drivers for health behavioral changes that mitigate the impact of climate change.
With advancement of infrared space telescopes during the past decade, infrared wavelength
regime has been a focal point to study various properties of galaxies with respect to
evolution of galaxies. Polycyclic Aromatic Hydrocarbons (PAHs) have emerged as one of the
most important features since these features dominate the mid-infrared spectra of
galaxies. These PAH features provide a great handle to calibrate star formation rates and
diagnose ionized states of grains. However, the PAH 3.3 μm feature has
not been studied as much as other PAH features since it is weaker than others and resides
outside of Spitzer capability, although it will be the only PAH feature accessible by JWST
for high-z galaxies. AKARI mJy Unbiased Survey of Extragalactic Sources in 5MUSES (AMUSES)
intends to take advantage of AKARI capability of spectroscopy in the
2 ~ 5 μm to provide an unbiased library of 44 sample
galaxies selected from a parent sample of 5MUSES, one of Spitzer legacy projects. For
these 3.6 μm flux limited sample galaxies whose redshifts range between
0 < z < 1, AMUSES will calibrate PAH 3.3
μm as a star formation rate (SFR) indicator while measuring ratios
between PAH features. We present preliminary results of AMUSES.
SiB6 has proved to a potentially useful material because of its excellent thermoelectrical properties above 700°C, low specific gravity, high degree of hardness, and moderate melting point. SiB6, which has poor sinterability with a conventional sintering technique due to the covalent characteristic, has been successfully densified fully using a spark plasma sintering(SPS) method. The SPS-processed specimens consisted of SiB6, SiB4 and SixBy phases. Pure SiB6 powder were densified fully at the sintering temperature of 1600°C. In particular, it was found that the rare earth element was very effective in evolving the microstructure of SiB6 phase, resulting in reducing the sintering temperature and controlling grain growth. These effects were discussed in details in terms of microstructure evolution during the SPS process.
Spark plasma sintering method was applied to Al-Cu-Fe and Al-Si-Cu-Fe gas-atomized powders to prepare almost pore-free cylindrical specimens with icosahedral and 1/1 cubic approximant phases, respectively. This investigation has revealed that a high density could be obtained despite the short period and low temperature imposed during spark plasma sintering. In comparison to hot press technique, these conditions are favorable since they limit the formation of secondary phases and avoid exaggerated grain growth. The Vickers microhardness and fracture toughness of these two alloy systems were found to be larger than those obtained from cast and hot pressed samples, which could be attributed to a strong bonding between powder particles and the small-grained microstructure of the bulk SPS quasicrystalline specimens.
The electrical and mechanical properties in indium-tin-oxide films deposited on polymer substrate were examined. The materials of substrates are polyethersulfone(PES), polycarbonate(PC), polyethylene terephthalate(PET) which have gas barrier layer and anti-glare coating for plastic-based devices. The experiments were performed by rf-magnetron sputtering using a special instrument and buffer layers. Therefore, we obtained a very flat polymer substrate deposited ITO film and investigated the effects of buffer layers, in addition to the instrument. Moreover, the influences of an oxygen partial pressure and post-deposition annealing in ITO films deposited on polymer substrates were clarified. X-ray diffraction observation, measurement of electrical property, and optical microscope observation were performed for the investigation of micro-structure and electro-mechanical properties. They indicated that as-deposited ITO thin films are amorphous and become quasi-crystalline after adjustment of oxygen partial pressure and thermal annealing above 180 °C. As the results, we obtained 20-25 Ω/ of ITO films with a good transmittance (above 80%) under 0.2 % oxygen contents and vacuum annealing. Furthermore, using organic buffer layer, we obtained ITO films which have rather high electrical resistance (40-45 Ω/ ) but have improved optical (more than 85%) and mechanical characteristics compared to the counterparts.
We studied on the effect of a deposition condition of precursor a-Si thin films on the shape and micro-structure of MILC. The a-Si thin films were prepared by Plasma Enhanced Chemical Vapor Deposition (PECVD) with silane and hydrogen as a source gas and the deposition temperature was varied from 100 to 400∼. The a-Si films deposited at a lower temperature showed a tendency to (111) crystals and leaving some a-Si residues in MILC region, while those with higher deposition temperature tended to be crystallized to (110). These differences were explained in terms of original hydrogen content and following structural changes by the dehydrogenation during annealing.