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661.
在大多数电子设备中,对系统电压进行监视是非常重要的,这样可保证处理器和其它IC在系统上电时被复位,还可以监测到电压的下降,从而把代码执行过程中出现问题的概率降到最小,避免存储器发生冲突或者系统工作不正常。 相似文献
662.
Maxim L. Kulygin Gregory G. Denisov Alexey V. Chirkov Sergey V. Kuzikov 《Journal of Infrared, Millimeter and Terahertz Waves》2006,27(4):591-613
We study 3-dimensional asymmetric diffraction problems for waveguide-based electro-dynamic systems, radiating to infinite free space. For calculations we utilize the FDTD (Finite Difference Time Domain) numerical simulation method with the UPML (Unsplit Perfectly Matched Layer) absorbing boundary conditions. This paper states that the FDTD method, in spite of its relatively low calculation speed, has an approved ability of solving certain problems that cannot be solved by the other traditional numerical simulation methods (the method of integral equation, the method of scattering matrix). 相似文献
663.
Winston H Wu Alex A T Bui Maxim A Batalin Duo Liu William J Kaiser 《IEEE transactions on information technology in biomedicine》2007,11(5):553-562
This paper presents an incremental diagnosis method (IDM) to detect a medical condition with the minimum wearable sensor usage by dynamically adjusting the sensor set based on the patient's state in his/her natural environment. The IDM, comprised of a naive Bayes classifier generated by supervised training with Gaussian clustering, is developed to classify patient motion in-context (due to a medical condition) and in real-time using a wearable sensor system. The IDM also incorporates a utility function, which is a simple form of expert knowledge and user preferences in sensor selection. Upon initial in-context detection, the utility function decides which sensor is to be activated next. High-resolution in-context detection with minimum sensor usage is possible because the necessary sensor can be activated or requested at the appropriate time. As a case study, the IDM is demonstrated in detecting different severity levels of a limp with minimum usage of high diagnostic resolution sensors. 相似文献
664.
通用的开关电容电荷泵式电压转换器都能将一个正电压源的电压转换为负电压,或使之增加一倍。但是.某些完全由ECL(射极耦合逻辑)电路组成的设备。只能提供一个负电压,如-5.2V。图1说明如何用一只开关电容转换器来获得一个适宜为ECL-TTL电平转换器和其它电路供电的正电源电压。 相似文献
665.
666.
We report the first synthesis of doped exfoliated graphite through the electrochemical oxidation of natural graphite in aqueous nickel nitrate and cobalt nitrate solutions, followed by heat treatment. The solutions are found to differ in electrochemical behavior during the anodic oxidation of graphite. The thermal properties of the oxidized graphite prepared by this procedure and utilized as a precursor to exfoliated graphite are described. The exfoliated graphite obtained under optimal conditions contains 2–60 wt % metal oxide and has a specific surface of 60–160 m2/g and loose density of 1.5–5 g/l. 相似文献
667.
SS Kataev NS Vasil'eva VG Avdeev LL Gil'var VG Starodvortseva OV Za?rat'iants 《Canadian Metallurgical Quarterly》1993,71(6):37-42
Exocrinous performance of the pancreatic gland under secretin-pancreozymin stimulation was studied in 76 patients with chronic diffuse diseases of the liver who were distinguished into 6 groups: those who suffered from chronic persistent hepatitis of viral and alcohol origin, chronic active hepatitis of viral origin, cirrhosis of the liver of viral and alcohol origin, primary biliary hepatocirrhosis. The results obtained were correlated with those from 11 normal persons (controls). Out of 76 examinees the disorders of exocrinous performance of the pancreatic gland were revealed in 75 persons. The most characteristic features were: a decrease in the basal and an increase in the stimulated volume of the pancreatic juice; a reduction of both basal and stimulated production of bicarbonates; a decrease in the trypsin and amylase fasting levels and their increment in the stimulated juice of the pancreatic gland. Disorder in the production of bicarbonates was stated as a most characteristic feature in the patients both with viral and alcohol origin of the disease but it was mostly manifest in the patients with hepatocirrhosis. Pronounced elevation of the activity of amylase and trypsin in the pancreatic juice was observed in patients with very high activity of disease development and in the patients who continuously used large amounts of alcohol. The authors suspected that alcohol abuse and the effect of hepatitis virus had an equal pathogenic impact on the liver and pancreatic gland. 相似文献
668.
New Apatite‐Type Oxide Ion Conductor,Bi2La8[(GeO4)6]O3: Structure,Properties, and Direct Imaging of Low‐Level Interstitial Oxygen Atoms Using Aberration‐Corrected Scanning Transmission Electron Microscopy 下载免费PDF全文
Matthew L. Tate Douglas A. Blom Maxim Avdeev Helen E. A. Brand Garry J. McIntyre Thomas Vogt Ivana Radosavljevic Evans 《Advanced functional materials》2017,27(8)
The new solid electrolyte Bi2La8[(GeO4)6]O3 is prepared and characterized by variable‐temperature synchrotron X‐ray and neutron diffraction, aberration‐corrected scanning transmission electron microscopy, and physical property measurements (impedance spectroscopy and second harmonic generation). The material is a triclinic variant of the apatite structure type and owes its ionic conductivity to the presence of oxide ion interstitials. A combination of annular bright‐field scanning transmission electron microscopy experiments and frozen‐phonon multislice simulations enables direct imaging of the crucial interstitial oxygen atoms present at a level of 8 out of 1030 electrons per formula unit of the material, and crystallographically disordered, in the unit cell. Scanning transmission electron microscopy also leads to a direct observation of the local departures from the centrosymmetric average structure determined by diffraction. As no second harmonic generation signal is observed, these displacements are non‐cooperative on the longer length scales probed by optical methods. 相似文献
669.
Synthesis,Crystal Structure,and Enhanced Luminescence of Garnet‐Type Ca3Ga2Ge3O12:Cr3+ by Codoping Bi3+ 下载免费PDF全文
Chengyin Liu Zhiguo Xia Maxim S. Molokeev Quanlin Liu 《Journal of the American Ceramic Society》2015,98(6):1870-1876
Garnet‐type compound Ca3Ga2Ge3O12 and Cr3+‐doped or Cr3+/Bi3+ codped Ca3Ga2Ge3O12 phosphors were prepared by a solid‐state reaction. The crystal structure of Ca3Ga2Ge3O12 host was studied by X‐ray diffraction (XRD) analysis and further determined by the Rietveld refinement. Near‐infrared (NIR) photoluminescence (PL) and long‐lasting phosphorescence (LLP) emission can be observed from the Cr3+‐doped Ca3Ga2Ge3O12 sample, and the enhanced NIR PL emission intensity and LLP decay time can be realized in Cr3+/Bi3+ codped samples. The optimum concentration of Cr3+ in Ca3Ga2Ge3O12 phosphor was about 6 mol%, and optimum Bi3+ concentration induced the energy‐transfer (ET) process between Bi3+ and Cr3+ ions was about 30 mol%. Under different excitation wavelength from 280 to 453 nm, all the samples exhibit a broadband emission peaking at 739 nm and the intensity of NIR emission increases owing to the ET behavior from Bi3+ to Cr3+ ions. The critical ET distance has been calculated by the concentration‐quenching method. The thermally stable luminescence properties were also studied and the introduction of Bi3+ can also improve the thermal stability of the NIR emission. 相似文献
670.
Preparation,Structure, and Up‐Conversion Luminescence of Yb3+/Er3+ Codoped SrIn2O4 Phosphors 下载免费PDF全文
Ming Guan Hong Zheng Lefu Mei Maxim S. Molokeev Jing Xie Tao Yang Xiaowen Wu Saifang Huang Zhaohui Huang 《Journal of the American Ceramic Society》2015,98(4):1182-1187
SrIn2O4, which shows lower phonon energy than CaIn2O4, is not only a good photocatalyst but also can be an excellent up‐conversion (UC) host to exhibits UC luminescence. In this work, Yb3+ and/or Er3+ doped SrIn2O4 phosphors were synthesized, and their UC luminescence properties were studied and compared with those in the CaIn2O4 host. The structure of SrIn2O4: 0.01Er3+ and SrIn2O4: 0.1Yb3+/0.01Er3+ samples were refined by the Rietveld method and found to that SrIn2O4: 0.1Yb3+/0.01Er3+ showed increasing unit cell parameters and cell volume, indicating In3+ sites were substituted successfully by Yb3+ and/or Er3+ ions. From the UC luminescence spectra and diffuse reflection spectra, Er3+‐doped SrIn2O4 showed very weak luminescence due to ground state absorption of Er3+; Yb3+/Er3+ codoped SrIn2O4 presented strong green (550 nm) and red (663 nm) UC emissions which were assigned to energy transfer from Yb3+ transition 2F7/2→2F5/2 to the Er3+ transition 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2. Comparing with CaIn2O4, Yb3+/Er3+ codoped SrIn2O4 showed obvious advantages with higher UC luminescent intensity. The pumping powers study showed that UC emissions in Yb3+/Er3+ codoped SrIn2O4 were attributed to energy transfer of Yb3+→Er3+ with a two‐photon process. The possible UC luminescent mechanism of Yb3+/Er3+‐doped SrIn2O4 was discussed. 相似文献