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951.
952.
Suresh Kumar Jangid Mrityunjay Kumar Singh Vasant Jadavji Solanki Mahadev Bhimappa Talawar Tribhuvan Nath Rabindra Kumar Sinha Srinandan Asthana 《Propellants, Explosives, Pyrotechnics》2016,41(2):377-382
A plastic‐bonded explosive (PBX) in the form of a sheet was formulated comprising of 1,3,5‐trinitroperhydro‐1,3,5‐triazine (RDX) and an hybrid binder system containing a linear thermoplastic polyurethane and a fluoroelastomer (Viton). The effect of a fluoroelastomer on the explosive as well as mechanical properties and thermal behavior of sheet explosive formulations were investigated and compared with a control formulation containing 90 % of RDX and 10 % of natural rubber (ISNR‐5). The replacement of 10 % natural rubber by a hybrid binder system led to an increase in the velocity of detonation (VOD) of the order of 250–950 m s−1 and better mechanical properties in terms of tensile strength (1.9–2.5 MPa) compared to the control formulation (RDX/ISNR‐5 (90/10)). The compatibility of ingredients and thermal decomposition kinetics of selected sheet explosive formulations were investigated by vacuum stability tests and differential scanning calorimetry (DSC). The results suggested better compatibility of RDX with the hybrid binder system (polyurethane/Viton), which is useful to reduce potential hazards in handling, processing, and storage. 相似文献
953.
954.
955.
Mahendra Nath Roy Milan Chandra Roy Saptarshi Basak 《International Journal of Thermophysics》2014,35(5):853-864
Qualitative and quantitative analysis of molecular interaction prevailing in glycine, l-alanine, l-valine, and aqueous solution of ionic liquid (IL) [1-ethylpyridinium tetrafluoroborate ( \(\mathrm{EPyBF}_{4})\) ] have been investigated by thermophysical properties. The apparent molar volume ( \(\phi _{V}\) ), viscosity \(B\) -coefficient, molal refraction ( \(R_{\mathrm{M}}\) ), and adiabatic compressibility ( \(\phi _{ K} )\) of glycine, l-alanine, and l-valine have been studied in 0.001 mol \({\cdot }\, \mathrm{dm}^{-3}\) , 0.003 mol \({\cdot }\, \mathrm{dm}^{-3}\) , and 0.005 mol \({\cdot } \,\mathrm{dm}^{-3}\) aqueous 1-ethylpyridinium tetrafluoroborate [ \(\mathrm{EPyBF}_{4}\) ] solutions at 298.15 K from the values of densities \((\rho )\) , viscosities ( \(\eta \) ), refractive index ( \(n_{\mathrm{D}})\) , and speed of sound \((u)\) , respectively. The extent of interaction, i.e., the solute–solvent interaction is expressed in terms of the limiting apparent molar volume ( \(\phi _{V}^0 )\) , viscosity \(B\) -coefficient, and limiting apparent molar adiabatic compressibility ( \(\phi _{K}^0)\) . The limiting apparent molar volumes ( \(\phi _{V}^0 )\) , experimental slopes ( \(S_{V}^*)\) derived from the Masson equation, and viscosity \(A\) - and \(B\) -coefficients using the Jones–Dole equation have been interpreted in terms of ion–ion and ion–solvent interactions, respectively. Molal refractions ( \(R_{\mathrm{M}})\) have been calculated with the help of the Lorentz–Lorenz equation. The role of the solvent (aqueous IL solution) and the contribution of solute–solute and solute–solvent interactions to the solution complexes have also been analyzed through the derived properties. 相似文献
956.
Jae Hong Park Imali A. Mudunkotuwa Jong Sung Kim Aditya Stanam Peter S. Thorne Vicki H. Grassian 《Aerosol science and technology》2014,48(7):768-776
This study introduces a spark discharge system (SDS) as a way to simulate welding fumes. The SDS was developed using welding rods as electrodes with an optional coagulation chamber. The size, morphology, composition, and concentration of the fume produced and the concentration of ozone (O3) and nitrogen oxides (NOX) were characterized. The number median diameter (NMD) and total number concentration (TNC) of fresh fume particles were ranged 10–23 nm and 3.1×107 ? 6×107 particles/cm3, respectively. For fresh fume particles, the total mass concentration (TMC) measured gravimetrically ranged 85–760 μg/m3. The size distribution was stable over a period of 12 h. The NMD and TNC of aged fume particles were ranged 81–154 nm and 1.5×106?2.7×106 particles/cm3, respectively. The composition of the aged fume particles was dominated by Fe and O with an estimated stoichiometry between that of Fe2O3 and Fe3O4. Concentrations of O3 and NOX were ranged 0.07–2.2 ppm and 1–20 ppm, respectively. These results indicate that the SDS is capable of producing stable fumes over a long-period that are similar to actual welding fumes. This system may be useful in toxicological studies and evaluation of instrumentation.
Copyright 2014 American Association for Aerosol Research 相似文献
957.
Nizar Bouguila Mukti Nath Ghimire 《Journal of Visual Communication and Image Representation》2010,21(7):613-626
Discrete data are an important component in many image processing and computer vision applications. In this work we propose an unsupervised statistical approach to learn structures of this kind of data. The central ingredient in our model is the introduction of the generalized Dirichlet distribution as a prior to the multinomial. An estimation algorithm, based on leave-one-out likelihood and empirical Bayesian inference, for the parameters is developed. This estimation algorithm can be viewed as a hybrid expectation–maximization (EM) which alternates EM iterations with Newton–Raphson iterations using the Hessian matrix. We propose then the use of our model as a parametric basis for support vector machines within a hybrid generative/discriminative framework. In a series of experiments involving scene modeling and classification using visual words, and color texture modeling we show the efficiency of the proposed approach. 相似文献
958.
Sintered tungsten carbide (WC) is a versatile metal matrix composite (MMC) material widely used in the tool manufacturing industries. Machining of this material with conventional cutting (CC) method is a real challenge compared to other difficult-to-cut materials. Ultrasonic elliptical vibration cutting (UEVC) method is a novel and non-conventional cutting technique which has been successfully applied to machine such intractable materials for the last decade. However, few studies have been conducted on cutting of WC using single point diamond tool (SPDT) applying the UEVC technique. This paper presents an experimental study on UEVC of sintered WC (~15% Co) using polycrystalline diamond (PCD) tools. Firstly, experiments have been carried out to investigate the effect of cutting parameters in the UEVC method in terms of cutting force, flank wear, surface finish while cutting sintered WC. The tests have revealed that the PCD tools in cutting of WC by the UEVC method results in better cutting performance at 4 μm depth of cut (DOC) as compared to both a lower DOC (e.g. 2 μm) and a higher DOC (e.g. 6 or 8 μm). Moreover, the cutting performance improves with the decrease in both the feed rate and cutting speed in the UEVC method like conventional turning (CT) method. A minimum surface roughness, Ra of 0.036 μm has been achieved on an area of about 1257 mm2 with the UEVC performance. The CT method has also been employed to compare its cutting performance against the UEVC method. It has been observed that the UEVC method results in better cutting performances in all aspects compared to the CT method. Theoretical analysis on the UEVC method and analysis of the experimental results have been carried out to explain the reasons of better surface finish at 4 μm DOC and better cutting performance of the UEVC method. 相似文献
959.
The bending piezoelectric coefficients β331 have been calculated (~1.5, 8.3, 10.0 μm) for various cases of unstretched and stretched, unpoled and corona poled, films of SAN. For the ABS films the value of β331~2.6 nC/m was obtained for unstretched and unpoled film, and 4.4 nC/m for corona poled films. A linear relation between β331 and d31 for the heat-treated samples indicates that the major contribution to bending piezoelectricity comes from the dipolar polarization 相似文献
960.
Nicholas A. Polomoff Ramesh Nath Premnath James L. Bosse Bryan D. Huey 《Journal of Materials Science》2009,44(19):5189-5196
High speed piezo force microscopy (HSPFM) is employed to investigate ferroelectric domain nucleation and growth of an exposed
PZT film. Twenty nanometer spatial and 10 ns temporal resolution is achieved using a pump:probe methodology, allowing area
switching and individual domain dynamics to be monitored. Two complementary investigations are performed, mapping switching
in either a single 2 μm × 2 μm area for 4.2 V pulses with durations ranging from 20 to 60 ns, or for 10 ns pulses with amplitudes
varying from −4 to −4.7 V. In this manner, nascent domains, as well as long-term growth, are efficiently quantified with substantial
statistical significance due to the hundreds of images that can reasonably be acquired in a practical experimental session.
The switching mechanism, areal switching rate, domain nucleation time, and domain wall velocity are each clearly independent
of pulse width. In contrast, these parameters are strongly influenced by increasing pulse heights, including a faster switching
rate, shorter nucleation times, and additional nucleation sites. This suggests a spatially and energetically heterogeneous
landscape of activation energies for domain reversal sites, only some of which can therefore participate in switching with
weak pulses but many of which are activated for strong pulses. These quantitative results, and the spatial, temporal, and
statistical benefits provided by HSPFM combined with pump:probe techniques, have important implications for determining ultimate
switching speeds, ideal device geometries, and optimal materials selection and processing. 相似文献