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Design and construction of a new ultraviolet sensor using CsI deposition in the ionization chamber
R. Souri,A. Negarestani,S. Souri,M. Farzan,M. Mahani 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.5
In this article, a UV sensor that is an appropriate tool for fire detection has been designed and constructed. The structure of this UV sensor is an air-filled single-wire detector that is able to operate undernormal air condition. A reflective CsI photocathode is installed at the end of the sensor chamber togenerate photoelectrons in the ion chamber. An electric current is produced by accelerating photoelectronsto the anode in the electric field. The detector is able to measure the intensity of the incidentUV rays whenever the current is sufficiently high. Therefore, the sensitivity coefficient of this sensor isfound to be 7.67 10 6 V/photons/sec.
Souri, M.,Kim, B. H.,Gruenewald, J. H.,Connell, J. G.,Thompson, J.,Nichols, J.,Terzic, J.,Min, B. I.,Cao, G.,Brill, J. W.,Seo, A. American Physical Society 2017 Physical review. B Vol.95 No.23
<P>We have investigated the electronic and optical properties of (Sr1-xCax)(2)IrO4 (x = 0-0.375) and (Sr1-yBay)(2)IrO4 (y = 0-0.375) epitaxial thin films, in which the bandwidth is systematically tuned via chemical substitutions of Sr ions by Ca and Ba. Transport measurements indicate that the thin-film series exhibits insulating behavior, similar to the J(eff) = 1/2 spin-orbit Mott insulator Sr2IrO4. As the average A-site ionic radius increases from (Sr1-xCax)(2)IrO4 to (Sr1-yBay)(2)IrO4, optical conductivity spectra in the near-infrared region shift to lower energies, which cannot be explained by the simple picture of well-separated J(eff) = 1/2 and J(eff) = 3/2 bands. We suggest that the two-peak-like optical conductivity spectra of the layered iridates originates from the overlap between the optically forbidden spin-orbit exciton and the intersite optical transitions within the J(eff) = 1/2 band. Our experimental results are consistent with this interpretation as implemented by a multiorbital Hubbard model calculation: namely, incorporating a strong Fano-like coupling between the spin-orbit exciton and intersite d-d transitions within the J(eff) = 1/2 band.</P>
Souri, H.,Yu, J.,Jeon, H.,Kim, J.W.,Yang, C.M.,You, N.H.,Yang, B.J. Pergamon Press ; Elsevier Science Ltd 2017 Carbon Vol.120 No.-
<P>Herein, we report a theoretical study of polymeric nanocomposites to provide physical insight into complex material systems in elastic regions. A self-consistent scheme is adopted to predict piezoresistive characteristics, and the effects of the interface and of tunneling on the effective piezoresistive and electrical properties of the nanocomposites are simulated. The overall piezoresistive sensitivity is predicted to be reduced when the lower interfacial resistivity of multi-walled carbon nanotubes (MWCNTs) and the higher effective stiffness of nanocomposites are considered. In addition, thin film nanocomposites with various MWCNT weight percentages are manufactured and their electrical performance capabilities are measured to verify the predictive capability of the present simulation. From experimental tests, the nanocomposites show clear piezoresistive behaviors, exhibiting a percolation threshold at less than 0.5 wt% of the MWCNTs. Three sets of comparisons between the experimental data and the present predictions are conducted within an elastic range, and the resulting good correlations between them demonstrate the predictive capability of the present model. (C) 2017 Elsevier Ltd. All rights reserved.</P>
Souri, H.,Nam, I.W.,Lee, H.K. Elsevier 2015 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.134 No.-
<P><B>Abstract</B></P> <P>A zinc oxide (ZnO)/polyurethane (PU)-based generator composite was fabricated and its piezoelectric performances were examined in the present work. In addition, the influence of multi-wall carbon nanotubes (MWNTs) and copper powder incorporation on the piezoelectric performance of composites was also studied. The performance level of the composites with various ratios of the constituents was compared in terms of piezoelectric responses obtained from three different tests, i.e., foot stamping, vehicle loading, and cyclic wheel loading tests. The foot stamping and vehicle loading tests revealed that the generator composite solely embedded with ZnO nano materials exhibited the best performance among the others, while the influence of MWNT and copper powder addition on the performance was minor. The cyclic wheel loading test (durability test) demonstrated that the generator composite sustained 2000 cycles of 400kg-weighed wheel loading and a prominent output voltage peak produced was as high as 40.45V.</P>
Effect of Antimony on the Optical and Physical Properties of Sb-V2O5-TeO2 Glasses
Dariush Souri,Mousa Mohammadi,Hamideh Zaliani 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.6
Ternary glass systems of the form xSb-(60-x) V2O5-40TeO2 (Sx glasses) with 0 ≤ x ≤ 15 (in mol. %) have been prepared by using the normal melt quenching technique. The optical absorption spectra of these glasses have been recorded within wavelength range of 190 - 1100 nm. The absorption spectrum fitting method was employed to obtain the energy band gap. In this method, only the measurement of absorbance spectrum of the glass is needed. The position of the absorption edge and therefore the optical band gap values were found to be depend on glass composition. Results show that the optical band gap is in the range 1.57 - 2.14 eV. For each sample, the width of the band tail was determined. The densities of present glasses were measured and the molar volumes were calculated. Also, some thermal properties such as glass transition temperature (Tg) and crystallization temperature (TCr) were obtained by using differential scanning calorimetry (DSC) technique, and from which the glass thermal stability S and glass forming tendency Kgl were calculated. Results show that these glasses (specially for x ≥ 10 mol. %) have good stability and therefore good resistance against thermal shocks for technological applications in fiber devices. Also, Tg values indicate the rigidity and packing of the samples increase with increasing the Sb concentration as a network modifier.
Dariush Souri,Ali Reza Khezripour,Mehdi Molaei,Masoud Karimipour 한국물리학회 2017 Current Applied Physics Vol.17 No.1
The using of a reliable and accurate new method (called in literature as derivation of absorption spectrum fitting (DASF)) for evaluation of the optical band gap (Eg) and also the exact nature of charge carriers optical transitions, is investigated in ZnSe and ZnSe:Cu nanocrystals (NCs) synthesized by rapid microwave irradiation. This method can be performed by using the output of UVeVisible spectroscopy. The obtained Eg values are within the range of 2.985e3.261 eV, depending to the microwave irradiation time and Cu dopant percentage (decreasing trend with increasing of irradiation time and Cu content). The DASF-based obtained results for ZnSe and ZnSe:Cu nanoparticles, showed the more precise values of band gap, with the same trend of previously qualitative reported data on the same samples. Also, the direct gap nature of their optical transitions was justified. To perform the method, there is no any need to the concentration of solutions and merely one need the direct absorption or transmission spectra. In other word, DASF technique was employed on ZnSe NCs to confirm its validity and to avoid non-precise reports on optical band gap which can affect on the device optimizations based on these samples. Moreover, using the values of Eg, refractive index and dielectric constant of each sample were obtained at the absorption edge. Also, the width of the tailing states in the gap (Urbach energy: ETail) was estimated and were within the range of 0.049e0.122 eV, which their very small values in compare with Eg imply to the sharp valence and conduction band edges; it means the good crystallinity nature of the produced samples.
Comparative evaluation of age and weathering condition of the Sirvan river terraces in western Iran
Bubak Souri,Makiko Watanabe 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.1
Comparative evaluation of age and weathering condition of alluvial deposits which associate to some environmental settings during their formation is a matter of interest in various fields of studies. The aim of this study was to compare age and weathering of two strath terraces of the Sirvan river in western Iran at its three cut-banks (1, 2 and 3) accessible for sampling. AMS 14C dating revealed 15090 ± 50 and 18510 ± 60 yrs BP for terrace T1 at the cut-banks 1 and 2, respectively, and 10870 ± 40, 11300 ± 40 and 14610 ± 40 yrs BP for terrace T2 at the cut-banks 1, 2, and 3, respectively. Evaluation of weathering using some coordination systems, where crystallinity ratio of iron oxides was considered as x-axis and indexes of either Parker or Product were set as y-axis showed more intensive weathering among older deposits for each of terraces T1 and T2. However, weathering condition of the two terraces were incomparable mostly due to deeper deposits and finer particle size distribution of terrace T1 than terrace T2 and also colder climatic condition of terrace T1 before formation of terrace T2. It seems all of these differences have discouraged weathering processes in terrace T1 through reducing of weathering factors influences. Color parameters of a* and b* in CIE color standard explained the intensity of reddish and yellowish of crystalline iron oxides of the river deposits, which functioned to discuss the order of emergence of the river terraces in the studied area.