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Automatic mesh generation is one of the most important parts in cims (Computer Integrated Manufacturing System). A method based on mesh grading propagation which automatically produces a triangular mesh in a multiply connected planar region is presented in this paper. Its core part is an algorithm for triangulating convex polygons. Making use of the shrinking polygons of a convex polygon and the mesh grading propagation rules, the algorithm automatically propagates boundary gradings into the interior of the region and generates meshes whose elements are close to the equilateral triangle in linear time, meanwhile sizes of elements between dense meshes and sparse meshes vary smoothly. The algorithm is incorporated with domain decomposition techniques to generate satisfactory quasi-uniform meshes for 2D arbitrary domains. Experiment results show that its running time is linear with both the number of nodes and the number of elements when generating meshes of different mesh densities for the same arbitrary domain.

From a simplified quantum-well model for a magnetic sandwich, it can be shown that in the variation of the number of occupied levels with the spacer layers, there exists an intrinsic periodicity, which leads the Fermi level to oscillate periodically. The intrinsic periodicity does not depend on the magnetic alignment but only on the quantum-well states themselves. The oscillation period can be approximately given by , where and are the effective masses of the electron in the lateral and perpendicular directions respectively, is the distance between the two neighbouring atomic layers, and is the electron density in the spacer layers. This makes one speculate that the long periodicity of the oscillatory coupling could be a result of the intrinsic periodicity, if and a small s-electron density are assumed. On the other hand, from the calculated energy bands for a thin film, it is found that the electronic structure is highly anisotropic, which is in agreement with this assumption. Therefore, it can be confirmed that the intrinsic periodicity plays an important role in the oscillatory coupling. An inverse photoemission experiment on Cu(100) films over Co can be explained quite well using this physical picture.

Automatic mesh generation is one of the most important parts in CIMS (Computer Integrated Manufacturing System). A method based on mesh grading propagation which automatically produces a triangular mesh in a multiply connected planar region is presented in this paper. The method decomposes the planar region into convex subregions, using algorithms which run in linear time. For every subregion, an algorithm is used to generate shrinking polygons according to boundary gradings and form Delaunay triangulation between two adjacent shrinking polygons, both in linear time. It automatically propagates boundary gradings into the interior of the region and produces satisfactory quasi-uniform mesh.

Water injection mode of molten fuel/coolant interaction is a key issue during the steam generator tube rupture in liquid metal reactors. The fragmentation behaviors of plunging water droplet into a high temperature molten tin liquid pool were studied by using a high speed video camera. Photographs of the water droplet configuration, the vaporization at the interface between the melt and water, and the vapor film disturbance were obtained. The results demonstrated that the water droplet in the molten tin pool was near spherical shape initially and the vapor was generated and accumulated in the bottom of the water droplet. The steam explosions happened when vapor film collapses finally.Copyright © 2012 by ASME

Melt-quenched compounds with Ag/(Ag+P) ratios from 0.5 to 0.67 form homogeneous glasses, while the 0.33 and 0.4 compositions show two amorphous phases. The 0.33 and 0.4 melt-quenched compounds were identified as glasses by x-ray diffraction, which was supported by differential scanning calorimetry and electric measurements. However, solid-state magic angle spinning-nuclear magnetic resonance at high speed (>8 kHz) revealed the existence of short-range ordered units in the 0.33 and 0.4 melt-quenched compounds. The electric conductivities, obtained by complex impedance analyses, of the melt-quenched compounds in the Ag-P-S system were studied along with glass transition temperature, T g , values and compared with Li + conductive sulfide glasses

Melt-quenched compounds with Ag/(Ag+P) ratios from 0.5 to 0.67 form homogeneous glasses, while the 0.33 and 0.4 compositions show two amorphous phases. The 0.33 and 0.4 melt-quenched compounds were identified as glasses by x-ray diffraction, which was supported by differential scanning calorimetry and electric measurements. However, solid-state magic angle spinning-nuclear magnetic resonance at high speed (>8 kHz) revealed the existence of short-range ordered units in the 0.33 and 0.4 melt-quenched compounds. The electric conductivities, obtained by complex impedance analyses, of the melt-quenched compounds in the Ag-P-S system were studied along with glass transition temperature, T g , values and compared with Li + conductive sulfide glasses

Leak Before Break (LBB) analysis is widely used to demonstrate system safety of pressurized equipments in nuclear plants. Developing a precise leak rate model for helium flow in complex geometry cracks is a key point for LBB analysis in Very High Temperature gas-cooled Reactor (VHTR). A literature study was firstly carried out concentrating on leak rate models proposed or used in LBB analysis. Helium leak rate experiments named DEDIFAR have been performed using elliptically converging and diverging artificial cracks in order to study the effect of the crack length ratio of a real through wall crack. Computational Fluid Dynamics (CFD) calculations of DEDIFAR experiments are presented to analyze the distributions and tendencies of flow parameters in converging cracks. Then, a parametric study was completed to investigate crack geometry effect on mass flow rate. Based on the results of these studies, the effects of upstream pressure and convergence ratio (inside over outside crack lengths) on mass flow rate are analyzed. The results show that the pressure loss mainly concentrates around the smallest exit crack area, and that when the convergence ratio equals or exceeds 20, flow parameters inside the crack domain remain almost the same.Copyright © 2010 by ASME

Glass formation and the local structure of ionically conductive crystalline and glassy compositions in the (Ag 2 S)(P x S 5 ) 1-x system have been investigated by 31 P magic-angle spinning (MAS) and spin-echo NMR. Glass formation encompasses the compositional range 0.5≤x≤0.67. 31 P MAS and spin-echo NMR data reveal striking differences in the local structures of the glasses and their crystalline counterparts. This result reinforces previous findings in related pseudobinary chalcogenide systems

This paper reports that the alternating current (ac) frequency responses for several sulfide ionically conductive glasses were investigated in the frequency range from 1 kHz to 1 GHz, which corresponds to the Larmor and probing frequencies for nuclear magnetic resonance (NMR) relaxation experiments. The additional conductivity under high frequency ac fields showed Arrhenius behavior in the temperature range studied (25 to 95{degrees}C). A frequency dependence of activation energy, E{sub tc}(f), for the additional conductivity was observed. E{sub tc}(f) showed a plateau region with an ac frequency range covering the NMR Larmor frequencies. NMR spin echo T{sub 2} experiments were carried out. The static quadrupolar and the heteronuclear dipolar contributions to the NMR lineshape were circumvented by the spin echo T{sub 2} experiments. The activation energies obtained, E{sub T2}, were consistent with E{sub tc}(f) plateau values for each glass composition. The consistency of these two experiments suggests that the additional conductivity is caused by the forced short-range motion of the mobile ions, while the NMR relaxation experiments characterize the short range thermal motion in the temperature range of 220 to 380 K.

Conflicting reports exist in the literature concerning the composition of thallium mercury iodide. Solid state synthesis with HgI2 and TlI has been reported to give Tl4HgI6 while synthesis from solution has been reported to give Tl2HgI4. In this report we show that the “orange compound” precipitating from solution is actually a 1:1 mole ratio mixture of Tl4HgI6 and HgI2. Pure Tl4HgI6, which is yellow, can be produced by heating the mixture at 100°C for several days to volatilize HgI2 or more simply, by adding Tl(I) to a solution containing 2:1 KI:K2HgI4 to provide the additional iodide ions needed for Tl4HgI6. Tl4HgI6, unlike Ag2HgI4 and Cu2HgI4, has no sharp thermochromic changes and has no measurable ionic conductivity. This provides another example of the significant role the metal ion plans in determining structure and properties of metal mercury iodide compounds.

The synthesis, characterization, and electrochemical properties of sulfide-based lithium glasses are reviewed. Special attention is given to the recent solid state NMR investigations shedding light on the network structure of these glasses and the role that conformers play in modifying the glass network. Electrochemical measurements show that some of these glasses are potentially useful in miniature and thin-film solid state batteries.

A glass processing method that employs a carbon-coated quartz container was used to study the B2S3 containing glasses i.e. (1−x) B2S3−xLi2S and 0.33[(1−y)B2S3−yP2S5]−0.67Li2S, which are extremely reactive towards quartz at temperatures above 400°C. This technique resulted in transparent glasses with a high Li2S content (0.5⩽x⩽0.75) for the (1−x)B2S3−xLi2S system. The glass forming region for the (1−x) P2S5−xLi2S glass system was expanded from 0.66⩽x⩽0.68 in previous studies to 0.5⩽x⩽0.7. The thermal behavior and the Li+ ionic conductivity of these glasses were analyzed. An exothermal peak was found during the glass transition for some B2S3 containing glasses, and the peak could be converted into a second glass transition by annealing at the peak temperature. The coformer sulfide glasses of the 0.33[(1−y)B2S3−yP2S5]−0.67Li2S system generally exhibited higher Li+ ionic conductivity than that of the single sulfide network former glasses, the room temperature conductivity of the glass with y=0.3 reached the value of 0.141 mS/cm.

Formular description of the magnetic field dependence of resistivity is of interest not only because of its theoretical importance, but also because it allows us to design magnetic-field-controlled devices. Using micromagnetic theory combined with charge carrier hopping and spin-polarized tunneling models, the magnetic field dependence of resistivity in half-metallic ferromagnet La 2/3 Sr 1/3 MnO 3 has been studied systematically. It has been shown that the resistivity is linearly dependent on magnetic field in a single grain. As for the resistivity of grain boundary (GB), namely the resistivity of spin transport across the boundary, it has an exponential relationship with magnetic field in the low-field region. Finally we give the analytical magnetoresistance formulas of polycrystalline, which agree well with the experimental results.

We investigate the magnetoelectric effect in Sr2CoGe2O7, which has a two-dimensional magnetic interaction between Co ions in the ab plane. This compound shows a weak magnetism and field-induced magnetic transition below the temperature of 7 K. It does not exhibit electric polarization under zero magnetic field. However, by applying an external magnetic field, the electric polarization is induced around its Neel temperature and increases with increasing magnetic field. The induced electric polarization in Sr2CoGe2O7 is almost two orders of magnitude smaller than that of Ba2CoGe2O7. This result suggests that the different ionic radius of the strontium and the barium anion plays a key role in determining the property of electric polarization. The origins of electric polarization and magnetoelectric effect are discussed.

The ideal battery separator would be infinitesimally thin, offer no resistance to ionic transport in electrolytes, provide infinite resistance to electronic conductivity for isolation of electrodes, be highly tortuous to prevent dendritic growths, and be inert to chemical reactions. Unfortunately, in the real world the ideal case does not exist. Real world separators are electronically insulating membranes whose ionic resistivity is brought to the desired range by manipulating the membranes thickness and porosity. It is clear that no single separator satisfies all the needs of battery designers, and compromises have to be made. It is ultimately the application that decides which separator is most suitable. We hope that this paper will be a useful tool and will help the battery manufacturers in selecting the most appropriate separators for their batteries and respective applications. The information provided is purely technical and does not include other very important parameters, such as cost of production, availability, and long-term stability. There has been a continued demand for thinner battery separators to increase battery power and capacity. This has been especially true for lithiumion batteries used in portable electronics. However, it is very important to ensure the continued safety of batteries, and this is where the role of the separator is greatest. Thus, it is essential to optimize all the components of battery to improve the performance while maintaining the safety of these cells. Separator manufacturers should work along with the battery manufacturers to create the next generation of batteries with increased reliability and performance, but always keeping safety in mind. This paper has attempted to present a comprehensive review of literature on separators used in various batteries. It is evident that a wide variety of separators are available and that they are critical components in batteries. In many cases, the separator is one of the major factors limiting the life and/or performance of batteries. Consequently, development of new improved separators would be very beneficial for the advanced high capacity batteries.

The absorption of light by photolytically generated silver colloid solutions is studied by thermal lens spectrophotometry. It is found that absorbance by silver nitrate solutions at 488 nm is a result of colloid formation. The absorbance is related to the particle size distribution and varies substantially from measurement to measurement even within the same colloidal solution. The shot-to-shot variance of the thermal lens signal is minimized by producing the colloid in a flowing AgNO3 solution, but still varies significantly from solution to solution at equal concentrations.

The ability of the 90 degrees-t1-180 degrees pulse sequence to produce accurate dipole-dipole coupling information in solids is investigated. To this end, the experimental 31P spin echo decays are measured for eighteen crystalline phosphides and phosphorus chalcogenides and compared with simulations, based on the known internuclear distances in these compounds. The experimental results are generally found accurate in compounds where the dominant contribution to the dipole-dipole coupling arises from nuclei in structurally inequivalent sites with large chemical shift anisotropies. For this situation, the quantum mechanical "flip-flop" term in the dipolar Hamiltonian is suppressed and the dipole-dipole coupling is entirely heteronuclear in character. All of those compounds that do not obey this condition show accelerated spin echo decays due to a fractional contribution of the flip-flop term and possibly incomplete refocusing of chemical shift terms on the time scale of the experiment. The results confirm on an empirical basis that the spin echo NMR technique can provide accurate dipole-dipole coupling information (and thus distance distributions) in disordered solids and glasses.

The synthesis, characterization, and electrochemical properties of sulfide-based lithiumglasses are briefly reviewed. Of the many probes that have been used to study these materials two will be discussed in more detail, namely solid state NMR and conductivity measurements at high frequency (106-109 Hz). Solid state NMR is particularly useful in understanding the network structure of these glasses and the role coformers play in modifying the glass network. Electrochemical measurements, including impedance at high frequency, give information concerning dynamic processes, and show that someof these glasses are potentially useful in miniature and thin-film solid state batteries.

Ionically conductive glasses have been synthesized using a 1:1 SiS2Li2S base glass and doping with lithium halides. The quenched glasses were ground to a powder and isostatically pressed into pellets with TiS2 electrodes. Conductivity was measured by complex impedance and the bulk resistance was obtained from an extrapolation of the straight line portion to the real axis. Conductivity of the base glass was 1.2×10−4 S-cm−1 at 25°C and increased several-fold when doped with lithium halide.

The local structure in Li2SSiS2LiIl glasses is investigated by solid state high resolution 6Li, 7Li, and 29Si NMR, using the technique of magic-angle sample spinning (MAS) in conjunction with absolute signal quantitation. Parallel studies of crystallized specimens indicate the presence of a crystalline compound with stoichiometry Li2SiS2, and a second phase with the likely stoichiometry Li4SiS4. Two distinct silicon environmentsare found in the latter phase. The 29Si MAS NMR spectra of crystalline lithium silicon sulfides are readily interpretable in terms of microstructures with differing fractions of non-bridging sulfur atoms attached to Si. In analogy to crystalline silicates, the 29Si resonance is shifted downfield with increasing numbers of non-bridging sulfur atoms, with an overall chemical shift range of ca. 30 ppm. In contrast, the 29Si MAS-NMR spectra of the glasses appear invariant over the entire region of glass formation, although the resolution would be sufficient to discern different distributions of microstructures if they weere present. Furthermore, in striking contrast to the oxide-analog system, no correspondence exists between the chemical shifts of the glasses and those observed in their crystalline counterparts. These highly unusual results suggest that the bonding concepts used to describe the local structures of oxidic glasses cannot be applied for the structural description of chalcogenide glasses, even if they are, as in the present case, stoichiometry-analog. Complementary information is provided by lithium NMR. The use of the rare isotope 6Li instead of 7Li offers the advantage of significantly improved spectroscopic resolution, and thus more accurate chemical shift determinations.

Non-oxide chalcogenide glasses based on more than one network former species have certain advantages for applications as solid electrolytes in batteries. To elucidate the influence of competitive glass-formation on the structural and motional properties of ionically conductive chalcogenide glasses, the system (Li2S)0.67[(B2S3)1−y (P2S5) y ]0.33 has been characterized comprehensively by DSC, electrical conductivity and6Li,7Li,31P, and11B solid state NMR techniques. The data obtained provide the first systematic characterization of the coformer effect in a chalcogenide glass system. Homogeneous glassy samples are formed fory=0.3 and 0.9≦y≦1.0, and microphase separated glasses for 0≦y≦0.2. The presence of a coformer leads to an increase in the electrical conductivity and a decrease of the activation energy, as compared to either binary system (Li2S-B2S3 or Li2S-P2S5), but only if homogeneous glasses are formed. The NMR data, in conjunction with systematic DSC and NMR studies of the binary systems (Li2S)x(B2S3)1−x (0.50≦x≦0.75) and (Li2S) x (P2S5)1−x (0.50≦x≦0.70), lead to the following conclusions: 1)11B MAS-NMR is well-suited to quantitate the amounts of three- and four coordinated boron atoms; in the binary glasses, the fraction of four-fold boron (N4) increases with decreasing Li2S/B2S3 ratio; in the ternary glasses N4 increases with increasingy. 2)31P MAS-NMR spectra of the binary glasses discriminate between three different phosphorus microenvironments, assigned to sulfide-analogs of metaphosphate, pyrophosphate, and orthophosphate species, respectively. These results suggest the applicability of network modification models originally developed for oxide glasses. For the ternary glasses, the DSC and NMR data of glasses with low phosphorus contents are consistent with a phase separation model involving a Li-rich thioborate glass that contains all of the phosphorus component and a glass phase less rich in lithium containing the four-fold boron atoms. In addition to the structural studies, the7Li spin-spin relaxation times (T 2) are used to characterize the mobility of the Li atoms. The activation energy of Li motion, determined from temperature dependentT 2 measurements and analyzed by using BPP theory differs from that determined from conductivity measurements by a factor of 2–3, possibly reflecting the inapplicability of this theory to the lithium diffusion process.

Glasses having the composition: have been prepared and glass transition temperatures, conductivity, and activation energies are reported. decreased from 337°C for to 208°C for while increased from 0.36 to 0.50 eV over this composition range. Measured conductivity reached a maximum value of 0.7 mS/cm at 25°C for . These glasses show promise as potential candidates as electrolytes for solid‐state batteries because the presence of phosphorus as a coformer increases the stability towards lithium metal.

A highly conductive glass with the composition: 0.14SiS 2 −0.09P 2 S 5 −0.47Li 2 S−0.30LiI has been synthesized at ambient pressure and quenching in liquid nitrogen. Its conductivity at 25°C was 2.1 mS/cm using lithium electrodes and exhibited dramatically improved stability towards lithium compared to SiS 2 -Li 2 S-LiI glasses. Glasses were also synthesized incorporating B 2 S 3 or Al 2 S 3 in place of P 2 S 5 in the SiS 2 -Li 2 S glass network. These, too, showed high conductivity and some improvement in stability towards lithium.

The utility of 29Si, 31 p, and 6.7 Li MAS-NMR at 7.05 T to provide structural information in non-oxide chalcogenide glasses is discussed in connection with experimental results obtained on the systems Li2 S-SiS2, Li2 S-SiS2 -P2S5, and Li2 S-P2 S5-B2 S329Si MAS-NMR data indicate that the principles governing glass formation in these systems are fundamentally different from those applicable to stoichiometry-analog oxide glasses. 31p MAS-NMR can be used to identify microphase-separation in glasses containing two network former constituents. The use of the rare isotope 6 Li instead of 7 Li offers the advantage of significantly improved spectroscopic resolution, enabling the presentation of the first comprehensive lithium NMR chemical shift scale in the solid state.