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F. Garcia J. Mesa O. Helene F. Milian T.E. Rodrigues 《Computer Physics Communications》2007,176(5):347-361
The code STATFLUX, implementing a new and simple statistical procedure for the calculation of transfer coefficients in radionuclide transport to animals and plants, is proposed. The method is based on the general multiple-compartment model, which uses a system of linear equations involving geometrical volume considerations. Flow parameters were estimated by employing two different least-squares procedures: Derivative and Gauss-Marquardt methods, with the available experimental data of radionuclide concentrations as the input functions of time. The solution of the inverse problem, which relates a given set of flow parameter with the time evolution of concentration functions, is achieved via a Monte Carlo simulation procedure.
Program summary
Title of program:STATFLUXCatalogue identifier:ADYS_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADYS_v1_0Program obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandLicensing provisions: noneComputer for which the program is designed and others on which it has been tested:Micro-computer with Intel Pentium III, 3.0 GHzInstallation:Laboratory of Linear Accelerator, Department of Experimental Physics, University of São Paulo, BrazilOperating system:Windows 2000 and Windows XPProgramming language used:Fortran-77 as implemented in Microsoft Fortran 4.0. NOTE: Microsoft Fortran includes non-standard features which are used in this program. Standard Fortran compilers such as, g77, f77, ifort and NAG95, are not able to compile the code and therefore it has not been possible for the CPC Program Library to test the program.Memory required to execute with typical data:8 Mbytes of RAM memory and 100 MB of Hard disk memoryNo. of bits in a word:16No. of lines in distributed program, including test data, etc.:6912No. of bytes in distributed program, including test data, etc.:229 541Distribution format:tar.gzNature of the physical problem:The investigation of transport mechanisms for radioactive substances, through environmental pathways, is very important for radiological protection of populations. One such pathway, associated with the food chain, is the grass-animal-man sequence. The distribution of trace elements in humans and laboratory animals has been intensively studied over the past 60 years [R.C. Pendlenton, C.W. Mays, R.D. Lloyd, A.L. Brooks, Differential accumulation of iodine-131 from local fallout in people and milk, Health Phys. 9 (1963) 1253-1262]. In addition, investigations on the incidence of cancer in humans, and a possible causal relationship to radioactive fallout, have been undertaken [E.S. Weiss, M.L. Rallison, W.T. London, W.T. Carlyle Thompson, Thyroid nodularity in southwestern Utah school children exposed to fallout radiation, Amer. J. Public Health 61 (1971) 241-249; M.L. Rallison, B.M. Dobyns, F.R. Keating, J.E. Rall, F.H. Tyler, Thyroid diseases in children, Amer. J. Med. 56 (1974) 457-463; J.L. Lyon, M.R. Klauber, J.W. Gardner, K.S. Udall, Childhood leukemia associated with fallout from nuclear testing, N. Engl. J. Med. 300 (1979) 397-402]. From the pathways of entry of radionuclides in the human (or animal) body, ingestion is the most important because it is closely related to life-long alimentary (or dietary) habits. Those radionuclides which are able to enter the living cells by either metabolic or other processes give rise to localized doses which can be very high. The evaluation of these internally localized doses is of paramount importance for the assessment of radiobiological risks and radiological protection. The time behavior of trace concentration in organs is the principal input for prediction of internal doses after acute or chronic exposure. The General Multiple-Compartment Model (GMCM) is the powerful and more accepted method for biokinetical studies, which allows the calculation of concentration of trace elements in organs as a function of time, when the flow parameters of the model are known. However, few biokinetics data exist in the literature, and the determination of flow and transfer parameters by statistical fitting for each system is an open problem.Restriction on the complexity of the problem:This version of the code works with the constant volume approximation, which is valid for many situations where the biological half-live of a trace is lower than the volume rise time. Another restriction is related to the central flux model. The model considered in the code assumes that exist one central compartment (e.g., blood) that connect the flow with all compartments, and the flow between other compartments is not included.Typical running time:Depends on the choice for calculations. Using the Derivative Method the time is very short (a few minutes) for any number of compartments considered. When the Gauss-Marquardt iterative method is used the calculation time can be approximately 5-6 hours when ∼15 compartments are considered. 相似文献2.
In this paper, we investigate the effect of water (H2O) molecules evolving from silicon dioxide (SiO2) film deposited by low pressure chemical vapor deposition (LPCVD) at 670 °C on the transistor characteristic of an electrically erasable programmable read only memory (EEPROM) cell. Fourier Transform Infra red (FT-IR) analysis reveals that H2O is captured during film deposition and diffused to silicon surface during high thermal processing. The diffused H2O molecules lower threshold voltage (Vt) of cell transistor and, thus, leakage current of the cell transistor is increased. In erased cell, Vt lowering is 0.25 V in which it increases leakage current of cell transistor from 1 to 100 pA. This results in the lowering of high voltage margin of a 512 Kb EEPROM from 2.8 to 2.6 V at 85 °C. 相似文献
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FPGA已经被广泛用于实现大规模的数字电路和系统,随着CMOS工艺发展到深亚微米,芯片的静态功耗已成为关键挑战之一。文章首先对FPGA的结构和静态功耗在FPGA中的分布进行了介绍。接下来提出了晶体管的漏电流模型,并且重点对FPGA中漏电流单元亚阈值漏电流和栅漏电流进行了详细的分析。最后根据FPGA的特点采用双阈值电压晶体管,关键路径上的晶体管采用低阈值电压栅的晶体管,非关键路径上的晶体管采用高阈值电压栅的晶体管,以此来降低芯片的静态功耗。 相似文献
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Koichi Sakita Kunio Takayama Kenji Awamoto Yasunobu Hashimoto 《Journal of the Society for Information Display》2003,11(1):139-144
Abstract— A simple model to calculate changes in wall voltage during weak discharge in three‐electrode ACPDPs was developed. A change in the wall voltage vector has an intrinsic direction for each discharge, which not only reveals the basis of problems in the ramp setup but also simplifies the analysis of cell operation during setup. New ramp‐setup waveforms designed for this model widened the operating margin. 相似文献
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本文提出了一种电源波动影响弱、低温飘、微功耗(〈1μw)的CMOS电压型积分器电路。它利用自偏置的恒流源电路结构以及MOSFETs的亚阈值特性产生一个nA级的恒流源,通过控制电路实现对电容充放电来获得积分电压。并且对电路结构、器件类型和器件尺寸进行了优化。仿真结果表明,得到了独立于电源电压、低温度系数、微功耗的积分电压。 相似文献
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介绍在等离子工艺中的等离子充电损伤,并且利用相应的反应离子刻蚀(RIE)Al的工艺试验来研究在nMOSFET器件中的性能退化。通过分析天线比(AR)从100:1到10000:1的nMOSFET器件的栅隧穿漏电流,阈值Vt漂移,亚阈值特性来研究由Al刻蚀工艺导致的损伤。试验结果表明在阈值Vt漂移中没有发现与天线尺寸相关的损伤,而在栅隧穿漏电流和低源漏电场下亚阈值特性中发现了不同天线比的nMOS器件有相应的等离子充电损伤。在现有的理解上对在RIEAl中nMOS器件等离子充电损伤进行了讨论,并且基于这次试验结果对减小等离子损伤提出了一些建议。 相似文献
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Rajesh Kumar S. Gautam In-Chul Hwang Jae Rhung Lee Nagesh Thakur 《Materials Letters》2009,63(12):1047-1050
Polyhedral nanocrystals of α-Fe2O3 are successfully synthesized by annealing FeCl3 on silicon substrate at 1000 °C in the presence of H2 gas diluted with argon (Ar). Uniformly shaped polyhedral nanoparticles (diameter ~ 50-100 nm) are observed at 1000 °C and gases flow rate such as; Ar = 200 ml/min and H2 = 150 ml/min. Non-uniform shaped nanoparticles (diameter ~ 20-70 nm) are also observed at an annealing temperature of 950 °C with lower gases flow rate (Ar = 100 ml/min and H2 = 75 ml/min). Nanoparticles are characterized in detail by field-emission electron microscopy (FE-SEM), energy dispersive X-ray (EDX) and high resolution transmission electron microscopy (HRTEM) techniques. HRTEM study shows well resolved (110) fringes corresponding to α-Fe2O3, and selected area diffraction pattern (SADP) confirms the crystalline nature of α-Fe2O3 polyhedral nanoparticles. It is observed that polyhedral formation of α-Fe2O3 nanocrystals depends upon annealing temperature and the surface morphology highly rely on the gas flow rate inside the reaction chamber. 相似文献
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A β-N-acetylhexosaminidase (β-NAHA) (EC 3.2.1.52) with molecular mass of 64.1 kDa and isoelectric point of 5.5 was purified from a commercial papaya latex preparation. The optimum pH for p-nitrophenyl-N-acetyl-β-d-glucosaminide (pNP-β-GlcNAc) hydrolysis was five; the optimum temperature was 50 °C; the Km was 0.18 mM, Vmax was 37.6 μmol min−1 mg−1 and activation energy (Ea) was 10.3 kcal/mol. The enzyme was thermally stable after holding at 30–45 °C for 40 min, but its activity decreased significantly when the temperature exceeded 50 °C. Heavy metal ions, Ag+ and Hg2+, at a concentration of 0.25 mM and Zn2+ and Cu2+, at a concentration of 0.5 mM, significantly inhibited enzyme activity. The β-NAHA had only one active site for binding both pNP-β-GlcNAc and p-nitrophenyl-N-acetyl-β-d-galactosaminide (pNP-β-GalNAc). A prototropic group with pKa value of about five on the enzyme may be involved in substrate binding and transformation, as examined by Dixon–Webb plots. 相似文献
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Abstract— Driving waveforms having both high‐speed address and low background were developed using Vt closed curve analysis. To prevent a misfired discharge during a sustain period, the voltage difference at the end of the ramp setup between the X‐Y electrodes remains constant. Because background luminance becomes higher (although the address discharge time lag becomes shorter) as the voltage difference between the A‐Y electrodes becomes larger, a low reset voltage and an address bias voltage were adopted during the ramp‐up period. 相似文献
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Thomas Benoist Claire Fenouillet-Beranger Pierre Perreau Christel Buj Philippe GalyDavid Marin-Cudraz Olivier FaynotSorin Cristoloveanu Pierre Gentil 《Microelectronic Engineering》2011,88(7):1276-1279
In this article, the impact in FDSOI technology, of ground plane and buried oxide (BOX) size on the robustness and on the NMOS triggering voltage (Vt1) is shown. We show experimentally that firstly thin BOX devices are more robust than thick BOX devices and secondly with a higher Vt1, thin BOX device purposes a larger range to trigger ESD network and to optimize design. 相似文献
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