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621.
An energy‐dispersive system is described for elemental mapping by X‐ray fluorescence spectrometry. The present study describes the design of an X‐ray fluorescence spectrometer and presents its performance in elemental mapping applications. The spectrometer is based on a new ring‐shaped collimator with a pinhole in the center of it and a ring‐shaped Am‐241 isotope mounted in the collimator as a source for excitation of X‐ray fluorescence. The photons were detected by high‐resolution Si (Li) detector coupled to a multi‐channel analyser and cooled by liquid nitrogen. In this study, we used two samples; one of them was made from pure elemental powders, and the second one was a piece of a stone and three types of maps were plotted. In the maps type one, the areas of the elements were shown with a single color. These maps only show the location of the elements in the sample. In the maps type two, the area of each element was shown with different colors because of the count (intensity) related to the area. In the third type of the maps for each element, depending on the elements' position on the sample, the counts were plotted in three dimensions. The areas with higher intensity have greater height, and areas with lower intensity have lower altitude. These two last types of maps provide information about the homogeneity or heterogeneity of the elemental distribution in the samples. The spectrometer can perform non‐destructive analyses of samples and objects in the air. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
622.
This study reports the development of a production scheduling system for the integrated management of production in large-scale, high-volume electronic assembly lines. The development of the system incorporates control and planning considerations by addressing the interaction of various subsystems. Stochastic and deterministic aspects of the problem environment are appropriately handled via relevant simulation and analytic models. By effecting a hierarchical breakdown of the problem environment, the system produces information used in practical decision making for production planning and scheduling. Procedures used encompass and address considerations for management of work-in-process, optimization of the various subsystems' performance, minimization of setup time effect, and inventory carrying costs. 相似文献
623.
G. Ahmadi 《Journal of sound and vibration》1980,71(1):9-15
The non-stationary random response of non-linear systems is considered. The technique of equivalent linearization is generalized for application to non-stationary non-linear random systems and several approximate methods of solution are presented. The example of a Duffing oscillator is studied in detail and its mean square response is evaluated and discussed. 相似文献
624.
R. D. Golpasha D. Karami R. Ahmadi E. Bagherzadeh 《Reaction Kinetics and Catalysis Letters》1993,51(2):393-400
Catalytic oxidative coupling of methane over perovskite CaTiO3 prepared by modified ceramic method has been studied. The C2 yield was 13% at 830 °C and promotion with Na4P2O7 did not improve considerably the catalyst peformance. Regarding reactor test and mechanism studies it is believed that charge deficient, oxygen O– generated by transforming oxygen adsorbed on surface defects and dissolved into bulk vacancies is responsible for activating methane (active site). Adsorbed oxygen generates the oxidizing sites for actived methane. Strict conditions are required for generation and regeneration of the activating sites in lattice. 相似文献
625.
Gerhard Buchbauer Waltraud Pernold Monika Ittner Mohammad T. Ahmadi Renate Dobner Reinhold Reidinger 《Monatshefte für Chemie / Chemical Monthly》1985,116(10):1209-1220
The synthesis of two new bicyclic phenylethylamine derivatives with potentially simpathomimetic effects is described. The synthesis of the isocamphane analogous apoephedrine (4) starts from the bicyclic methylketone5 and leads via its -bromoderivative6 and the corresponding tosylamidoketone8 to4. The synthesis of the title compound2 has been accomplished by preparing the -oximinoketone19 from the bicyclic ethylketone15 with subsequent reduction to the amino alcohol derivative20 and final selective monomethylation by theJohnstone procedure via the corresponding trifluoroacetamide.
Herrn Prof. Dr.K. Kratzl mit den besten Wünschen zum 70. Geburtstag gewidmet. 相似文献
626.
In order to study the mass generation of the vector fields in the framework of a conformal invariant gravitational model,
the Weyl–Dirac theory is considered. The mass of the Weyl’s meson fields plays a principal role in this theory, it connects
basically the conformal and gauge symmetries. We estimate this mass by using the large-scale characteristics of the observed
universe. To do this we firstly specify a preferred conformal frame as a cosmological frame, then in this frame, we introduce
an exact possible solution of the theory. We also study the dynamical effect of the massive vector meson fields on the trajectories
of an elementary particle. We show that a local change of the cosmological frame leads to a Hamilton–Jacobi equation describing
a particle with an adjustable mass. The dynamical effect of the massive vector meson field presents itself in the form of
a correction term for the mass of the particle. 相似文献
627.
Gh. Solookinejad M. Jabbari E. Ahmadi Sangachin S. H. Asadpour 《International Journal of Theoretical Physics》2018,57(1):20-27
In this paper, we discuss the transmission properties of weak probe laser field propagate through slab cavity with defect layer of carbon-nanotube quantum dot (CNT-QD) nanostructure. We show that due to spin-orbit coupling, the double electromagnetically induced transparency (EIT) windows appear and the giant Kerr nonlinearity of the intracavity medium can lead to manipulating of transmission coefficient of weak probe light. The thickness effect of defect layer medium has also been analyzed on transmission properties of probe laser field. Our proposed model may be useful for integrated photonics devices based on CNT-QD for applications in all-optical systems which require multiple EIT effect. 相似文献
628.
Vahideh KhademHosseini Daryoosh Dideban MohammadTaghi Ahmadi Razali Ismail 《Brazilian Journal of Physics》2018,48(4):406-410
Single-electron transistors (SETs) are nano devices which can be used in low-power electronic systems. They operate based on coulomb blockade effect. This phenomenon controls single-electron tunneling and it switches the current in SET. On the other hand, co-tunneling process increases leakage current, so it reduces main current and reliability of SET. Due to co-tunneling phenomenon, main characteristics of fullerene SET with multiple islands are modelled in this research. Its performance is compared with silicon SET and consequently, research result reports that fullerene SET has lower leakage current and higher reliability than silicon counterpart. Based on the presented model, lower co-tunneling current is achieved by selection of fullerene as SET island material which leads to smaller value of the leakage current. Moreover, island length and the number of islands can affect on co-tunneling and then they tune the current flow in SET. 相似文献
629.
Yaser Ghazi Akbar Vaseghi Sepideh Ahmadi Fatemeh Haddadi 《Journal of fluorescence》2018,28(2):633-638
Gene expression analysis is considered to be extremely important in many different biological researches. DNA-based diagnostic test, which contributes to DNA identification, has higher specificity, cost, and speed than some biochemical and molecular methods. In this study, we try to use the novel nano technology approach with Multiplex RT-PCR and Gold nano particular probes (GNPs-probes) in order to get gene expression in Curcumas melons. We used Agrobacterium tumefactions for gene transfer and GUS reporter gene as a reporter. After cDNA synthesis, Multiplex PCR and Multiplex RT-PCR techniques were used. Finally, probes were designed for RNA of GUS and Actin genes, and then the analysis of the gene expression using the probes attached to GNPs was carried out and the color changes in the GNPs were applied. In the following, probes hybridization was checked with DNA between 400 to 700 nm wavelengths and the highest rate was observed in the 550 to 650 nm. The results show that the simultaneous use of GNP-attached detectors and Multiplex RT-PCRcan reduce time and costmore considerably than somelaboratory methods for gene expiration investigation. Additionally, it can be seen thatthere is an increase in sensitivity and specificity of our investigation. Based on our findings, this can bea novel study doneusingMultiplex RT-PCRand unmodified AuNPs for gene transfer and expression detection to plants. We can claim that this assay has a remarkable advantage including rapid, cost-effectiveness, specificity and accuracy to detect transfer and expression genes in plants. Also,we can use this technique from other gene expressionsin many different biology samples. 相似文献
630.
In this paper, we consider a repairable system with minimal repairs whose number of repairs is a positive random variable with a given probability vector. Some preservation theorems and aging properties of repairable systems are established. Under the condition that at time t the system is working, a new random variable for the residual lifetime of the system is proposed. Some stochastic ordering results among the lifetimes and residual lifetimes of two systems are obtained. Similar results for coherent systems with independent components and exchangeable components were obtained in the previous literature. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献