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排序方式: 共有2197条查询结果,搜索用时 234 毫秒
991.
Igor R. Sagdeev Andrzej K. Drukier Dan J. Welsh 《Journal of Low Temperature Physics》1993,93(3-4):761-766
Progress in Ge detector technology has resulted in ultralow backgrounds of less than 0.3 counts keV–1 kg–1 d–1 at energies between 5 and 12 keV, and less than 1.0 counts kev–1 kg–1 d–1 for energies between 3 and 5 keV. Coupled with good energy resolution, 0.4 keV FWHM at 10 keV, this allows searches for DM particles with m 8 GeV/c2.Electromagnetic interference and acoustical pick-up are the main sources of background in the best Ge detectors. These problems are even more important in cryogenic WIMP detectors under development. A PC-based on line pulse shape analysis system is presented which permits rejection of about 95% percent of the EMI/ acoustical background. The hardware uses a low cost, commercially available digital storage oscilloscope. The software consists of about 20,000 lines of code in Pascal and assembly language. We tested this system using a low radioactive background Ge-system on the Earth's surface. For low energy events (27 keV photons) this system permits improvement in the background from 0.1 cpm to 2 cpd. 相似文献
992.
Franc Novak Igor MozetiČ Marina Santo-Zarnik Anton Biasizzo 《Analog Integrated Circuits and Signal Processing》1993,4(3):215-229
We describe a computer-aided approach to automatic fault isolation in active analog filters which enhances the design-for-test (DFT) methodology proposed by Soma (1990). His primary concern was in increased controllability and observability while the fault isolation procedure was sketched only in general terms. We operationalize and extend the DFT methodology by using CLP() to model analog circuits and by a model-based diagnosis approach to implement a diagnostic algorithm. CLP() is a logic programming language which combines symbolic and numeric computation. The diagnostic algorithm uses different DFT test modes and results of voltage measurements for different frequencies and computes a set of suspected components. Ranking of suspected components is based on a measure of (normalized) standard deviations from predicted mean values of component parameters. The diagnosis is performed incrementally, in each step reducing the set of potential candidates for the detected fault. Case studies show encouraging results in isolation of soft faults of a given low-pass biquad filter. 相似文献
993.
994.
Igor Aleksejev Sergei Devadze Artur Jutman Konstantin Shibin 《Journal of Electronic Testing》2016,32(3):245-255
This paper presents a method for optimization of board-level scan test with the help of reconfigurable scan-chains (RSCs) implemented in a programmable logic of FPGA. Despite that the RSC concept is a well-known solution for scan-based test time reduction, the usage of RSC may lead to un-acceptable hardware overhead. In our work, we are targeting a completely new approach of exploiting on-board FPGA resources that being unconfigured are typically available during the manufacturing test phase for carrying out tests using temporarily implemented virtual RSC structures. As the allocated FPGA logic is re-claimed for functional use after the test is finished, the presented method delivers all the advantages of RSCs at no extra hardware cost. Experimental results show that the proposed virtual RSCs can fit into all available commercial FPGAs providing a significant test time reduction in comparison with state-of-the-art Boundary Scan test tecnique. 相似文献
995.
Gorev Nikolai B. Gorev Vyacheslav N. Kodzhespirova Inna F. Shedlovsky Igor A. Sivakumar P. 《Water Resources Management》2022,36(5):1679-1691
Water Resources Management - This paper shows that the zero flow treatment algorithm and the convergence criteria of EPANET 2.2, the latest version of the EPANET 2 open-source software package, may... 相似文献
996.
Nekrasov Igor Ovchinnikov Sergei 《Journal of Superconductivity and Novel Magnetism》2022,35(4):959-963
Journal of Superconductivity and Novel Magnetism - The experimental discovery of the highest, up to 0 degree Celsius, superconducting transition temperatures T $$_c$$ in the class of so-called... 相似文献
997.
Yocefu Hattori Mohamed Abdellah Igor Rocha Mariia V. Pavliuk Daniel L.A. Fernandes Jacinto Sá 《Materials Today》2018,21(6):590-593
Light-driven proton-coupled electron transfer (PCET) reactions on nanoplasmonics would bring temporal control of their reactive pathways, in particular, prolong their charge separation state. Using a silver nano-hybrid plasmonic structure, we observed that optical excitation of Ag-localized surface plasmon instigated electron injection into TiO2 conduction band and oxidation of isopropanol alcoholic functionality. Femtosecond transient infrared absorption studies show that electron transfer from Ag to TiO2 occurs in ca. 650?fs, while IPA molecules near the Ag surface undergo an ultrafast bidirectional PCET step within 400?fs. Our work demonstrates that ultrafast PCET reaction plays a determinant role in prolonging charge separation state, providing an innovative strategy for visible-light photocatalysis with plasmonic nanostructures. 相似文献
998.
Dmitrii V Ludin Sergey D Zaitsev Alexey V Markin Ivan D Grishin Semen S Sologubov Tatyana A Kovylina Igor L Fedushkin 《Polymer International》2022,71(1):86-97
We developed a new approach to obtain polylactide hybrid block copolymers with vinyl monomers (styrene, methyl methacrylate, methyl acrylate) through the realization of a reaction sequence using triethylborane and various p-quinones. The method offered includes two stages. In the first stage, a chain-transfer agent was obtained by borylation of the terminal hydroxyl groups of polylactide. The second stage was vinyl monomer radical polymerization in the presence of p-quinone accompanied by SH2-substitution at the boron atom.1,4-Naphthoquinone, 2,3-dimethyl-1,4-benzoquinone, duroquinone and 2,5-di-tert-butyl-1,4-benzoquinone were used as synthetic polymer chain growth mediators. It is shown that 1,4-naphthoquinone and 2,3-dimethyl-1,4-benzoquinone, similar in their characteristics, are effective agents providing the realization of reversible-deactivation radical polymerization. Realization of reversible-deactivation radical polymerization was proved with the analysis of the kinetics of block copolymerization, molecular weight characteristics and compositional homogeneity of block copolymers as well as its further capability to elongate the polymer chain. Synthesized block copolymers have a high thermal stability compared to the initial borylated polylactide. © 2021 Society of Industrial Chemistry. 相似文献
999.
Mikhail A. Matsko Nina V. Semikolenova Vladimir A. Zakharov Igor E. Soshnikov Inna K. Shundrina Wen-Hua Sun 《应用聚合物科学杂志》2021,138(20):50436
Comparative data on the micro-structures and properties of branched polyethylenes (BPE) produced via ethylene homopolymerization over homogeneous N,N-α-diimine LNiBr2 complexes with different ligand composition (AlEt2Cl as a cocatalyst) and corresponding supported catalysts LNiBr2/SiO2(Al) (Al[iso-Bu]3 as a cocatalyst) are presented. Noticeable differences were observed between micro-structures of BPEs obtained using homo- and heterogeneous LNiBr2 complexes as catalysts. Supported catalysts produce BPEs with the majority of methyl branches (17–18 CH3(1000 C)−1 characterized by different molecular masses (1800–210 kg mol−1) and molecular weight distributions (Mw[Mn]−1 = 5.9 and 2.6). Thermal and mechanical properties of these BPE samples obtained over supported Ni catalysts are similar to those of commercial LLDPE samples prepared with metallocene and Ziegler-Natta catalysts. 相似文献
1000.
The paper focuses on experimental verification of a new approach to evaluate strength of structural elements via electrical resistance scanning. The approach utilizes explicit cross-property connections. In the case of multiple parallel cracks, we reconstruct certain characteristics of the microstructure from resistance measurements and evaluate the corresponding strength reduction. The results are compared to actual fracture tests of preconfigured specimens. Experimental strength measurements show strong correlation to the results predicted by the resistance scanning technique. 相似文献