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81.
A.M. Reda 《Radiation measurements》2011,46(10):1187-1193
Shielding for a D–T sealed neutron generator has been designed using the MCNP5 Monte Carlo radiation transport code. The neutron generator will be used in field for the detection of explosives, landmines, drugs and other ‘threat’ materials. The optimization of the detection of buried objects was started by studying the signal-to-noise ratio for different geometric conditions. 相似文献
82.
A comparative study was conducted to study the effects that two different polymerization solvents would have on the properties of imprinted polymer microparticles prepared using precipitation polymerization. Microparticles prepared in chloroform, which previous results indicated was the optimal solvent for molecular imprinting of nitroaromatic explosive compounds, were compared to water, which was hypothesized to decrease water swelling of the polymer and allow enhanced rebinding of aqueous template. The microparticles were characterized and were integrated into a fluorescence sensing mechanism for detection of nitroaromatic explosive compounds. The performance of the sensing mechanisms was compared to illustrate which polymerization solvent produced optimal imprinted polymer microparticles for detection of nitroaromatic molecules. Results indicated that the structures of microparticles synthesized in chloroform versus water varied greatly. Sensor performance studies showed that the microparticles prepared in chloroform had greater imprinting efficiency and higher template rebinding than those prepared in water. For detection of 2,4,6-trinitrotoluene, the chloroform-based fluorescent microparticles achieved a lower limit of detection of 0.1 μM, as compared to 100 μM for the water-based fluorescent microparticles. Detection limits for 2,4-dinitrotoluene, as well as time response studies, also demonstrated that the chloroform-based particles are more effective for detection of nitroaromatic compounds than water-based particles. These results illustrate that the enhanced chemical properties of using the experimentally determined optimal polymerization solvent overcome deformation of imprinted binding sites by water swelling and benefits of using the polymerization solvent for rebinding of the template. 相似文献
83.
炸药爆温的光纤测温法测量 总被引:3,自引:0,他引:3
本文阐述了光纤测温技术依据的原理,给出了多通道瞬时光纤测温装置的构成。利用该装置对液体炸药硝基甲烷的实际爆轰温度及其光谱发射率进行了实验测量,结果分别为3700±100(K)和0.71±0.15。 相似文献
84.
Hamdi Fathallah 《随机分析与应用》2013,31(2):238-257
In this article, we establish the almost-sure central limit theorem (ASCLT) for a quasi-left continuous vector martingale with explosive and mixed (regular and explosive) growth. We also prove a quadratic extension and establish several new central limit theorems associated with the obtained ASCLT. Finally, we study the problem of parameter estimation in the particular case of multidimensional diffusion processes, which illustrates in a concrete manner the use of our results. 相似文献
85.
《Wave Motion》2018
In this paper, we theoretically describe a magnetoelastic system with an explosive instability in which the magnetic energy can be converted into the mechanical one via an extremely efficient channel. The principle is based on the amplification of acoustic waves traveling in an antiferromagnetic crystal under the action of transversal electromagnetic pumping. It is known that such parametric interaction can produce an exponential acoustic wave amplification. Our finding consists in the addition of another pumping channel by means of a discrete resonant acoustic mode whose impact is similar to the Feshbach resonance observed in another physical system (ultra-cold gazes). The addition of the second pumping mechanism results in the explosive instability having the dynamics of a singularity at a finite time instead of the exponential growth. In our example the traveling waves are Lamb waves in an antiferromagnetic plate, and the additional pumping is a shear resonance. We establish equations governing the considered three-phonon parametric instability, theoretically analyze the instability conditions, and give a relevant numerical example illustrating the explosive magneto-acoustic dynamics. It is shown that the explosive scenario can occur with a very low signal level i.e. Lamb waves amplitudes comparable to spontaneous noise in the system. 相似文献
86.
W.D. Liu K.X. Liu Q.Y. Chen J.T. Wang H.H. Yan X.J. Li 《Applied Surface Science》2009,255(23):9343-9347
Using an adjusted explosive welding technique, an aluminum plate has been coated by a Fe-based metallic glass foil in this work. Scanning electronic micrographs reveal a defect-free metallurgical bonding between the Fe-based metallic glass foil and the aluminum plate. Experimental evidence indicates that the Fe-based metallic glass foil almost retains its amorphous state and mechanical properties after the explosive welding process. Additionally, the detailed explosive welding process has been simulated by a self-developed hydro-code and the bonding mechanism has been investigated by numerical analysis. The successful welding between the Fe-based metallic glass foil and the aluminum plate provides a new way to obtain amorphous coating on general metal substrates. 相似文献
87.
The possible manifestations of thermodynamical instability (explosive vaporisation) are discussed for different regimes of laser heating of the metal/transparent liquid system. The present calculations show that the explosive vaporisation in the metastable region may occur if the nucleation rate is high enough. This condition is achievable if the surface tension of the superheated liquid tends to zero near the spinodal. It is also shown that the dependence of the phase explosion time on laser intensity markedly changes its behaviour when the water temperature reaches the spinodal. 相似文献
88.
The interaction between TNT and a vitally significant biological molecule, epinephrine, was investigated at the level of density functional theory. Two models are constructed; (i) an intimate pair of TNT and epinephrine and (ii) a π complex of them. The calculations (in vacuo conditions) have showed that these molecules in the intimate pair model orient themselves in an angular arrangement, whereas a π complex formation between these molecules is quite likely in the case of parallel arrangement of aromatic rings. The calculated electrostatic charges, UV and NMR spectra support the idea of a strong interaction between TNT and epinephrine whatever the type of interaction is. 相似文献
89.
Robert G. Ewing Melanie J. Waltman 《International Journal for Ion Mobility Spectrometry》2009,12(2):65-72
In an effort to better understand the formation of negative reactant ions in air produced by an atmospheric pressure corona
discharge source, the neutral vapors generated by the corona were introduced in varying amounts into the ionization region
of an ion mobility spectrometer/mass spectrometer containing a 63Ni ionization source. With no discharge gas the predominant ions were O2
−, however, upon the introduction of low levels of discharge gas the NO2
− ion quickly became the dominant species. As the amount of discharge gas increased the appearance of CO3
− was observed followed by the appearance of NO3
−. At very high levels, NO3
− species became effectively the only ion present and appeared as two peaks in the IMS spectrum, NO3
− and the NO3
−·HNO3 adduct, with separate mobilities. Since explosive compounds typically ionize in the presence of negative reactant ions, the
ionization of an explosive, RDX, was examined in order to investigate the ionization properties with these three primary ions.
It was found that RDX forms a strong adduct with both NO2
− and NO3
− with reduced mobility values of 1.49 and 1.44 cm2V−1 s−1, respectively. No adduct was observed for RDX with CO3
− although this adduct has been observed with a corona discharge mass spectrometer. It is believed that this adduct, although
formed, does not have a sufficiently long lifetime (greater than 10 ms) to be observed in an ion mobility spectrometer. 相似文献
90.
Ahmed Hamydy 《Journal of Mathematical Analysis and Applications》2010,371(2):534-169
Assume that Ω is a bounded domain in RN (N?3) with smooth boundary ∂Ω. In this work, we study existence and uniqueness of blow-up solutions for the problem −Δp(u)+c(x)|∇u|p−1+F(x,u)=0 in Ω, where 2?p. Under some conditions related to the function F, we give a sufficient condition for existence and nonexistence of nonnegative blow-up solutions. We study also the uniqueness of these solutions. 相似文献