Low-voltage CMOS transconductance cell based on parallel operationof triode and saturation transconductors

A new linearity improvement technique for CMOS triode transconductors is presented. The idea is based on the parallel operation of CMOS triode and saturation region transconductors. Simulation results indicate that 0.01% THD and linearity is possible with 800 mV peak-to-peak input differential signals and 1.5 V supply voltage     

Electromagnetic scattering from nonlinear anisotropic cylinders. I.Fundamental frequency

The solution of the problem of electromagnetic scattering of obliquely incident plane waves by homogeneous, nonlinear anisotropic cylindrical structures is obtained. The medium of the scatterer is characterized by Volterra-type integrals for the electric and magnetic flux density vectors D and B, respectively. The nonlinear problem is solved using the perturbation method. The effects of nonlinearities on the field properties both inside and outside the scatterer, together with the effect on the radar cross section, are investigated for the fundamental frequency components. To demonstrate the validity of the approach, the results obtained by the perturbation method are compared with those obtained using the plane wave representation method of D. Censor (1983), where the iteration method is used to solve the resulting dispersion equation. The results are in very good agreement in both amplitude and phase of the fields for the case of very weak nonlinearity. When the relative magnitude of the nonlinear component of the permittivity is increased, the iteration method shows a faster divergence of the phase from the linear phase     

A design of experiment analysis of serial EEPROM endurance

The results of a study using a design of experiments approach to examine the effects of environmental operating conditions on serial EEPROM endurance are presented. The conditions studied in the experiment were operating temperature, applied voltage, device type, array usage, write cycles per day, data pattern, and write pulse width. An ANOVA table showing the significant effects and an estimation of the value of the effects using an error minimization technique is presented. While the techniques presented are relatively simple, they may be useful as a quick check of acceleration effects in EEPROM endurance cycling, without the use of extensive factorial experiments. The results show temperature, array size and voltage to be the most important effects on EEPROM endurance cycling. The temperature effect matches other published data.     

Coulometric methods for uranium and plutonium determination

Data on coulometric methods for U and Pu determination in various nuclear materials are presented, analyzed, and summarized. Coulometric determination methods at controlled current and controlled potential are considered. The main principles of the U and Pu determination procedures based on the use of the UO₂ ²⁺/U⁴⁺, Pu⁴⁺/Pu³⁺, and PuO₂ ²⁺/Pu⁴⁺ redox couples are presented. Various methodical factors influencing the error of the U and Pu determination, such as sample weight; supporting electrolyte composition; oxidation and reduction potentials; current; electrode material, shape, and activation procedure; impurity elements, etc., are discussed. Procedures for joint coulometric determination of U and Pu are considered separately. The main methods used by the authors for eliminating the mutual effect of U and Pu in their joint determination are described.     

Heat and Particle Transport in the Initial Phase of Ohmic Discharges in the Globus-M Spherical Tokamak

Technical Physics Letters - The results of experiments and simulations of the transport of heat and particles in the Globus-M spherical tokamak are presented. Investigations were carried out in the...     

Spatially resolved electronic and vibronic properties of single diamondoid molecules

Diamondoids are a unique form of carbon nanostructure best described as hydrogen-terminated diamond molecules. Their diamond-cage structures and tetrahedral sp3 hybrid bonding create new possibilities for tuning electronic bandgaps, optical properties, thermal transport and mechanical strength at the nanoscale. The recently discovered higher diamondoids have thus generated much excitement in regards to their potential versatility as nanoscale devices. Despite this excitement, however, very little is known about the properties of isolated diamondoids on metal surfaces, a very relevant system for molecular electronics. For example, it is unclear how the microscopic characteristics of molecular orbitals and local electron-vibrational coupling affect electron conduction, emission and energy transfer in the diamondoids. Here, we report the first single-molecule study of tetramantane diamondoids on Au(111) using scanning tunnelling microscopy and spectroscopy. We find that the diamondoid electronic structure and electron-vibrational coupling exhibit unique and unexpected spatial correlations characterized by pronounced nodal structure across the molecular surfaces. Ab initio pseudopotential density functional calculations reveal that much of the observed electronic and vibronic properties of diamondoids are determined by surface hydrogen terminations, a feature having important implications for designing future diamondoid-based molecular devices.     

Stability of orthotropic thin-walled cylindrical shells under torsion. Part 1. Theory

An analytical solution to the problem of stability of orthotropic and structurally orthotropic cylindrical shells under torsion has been obtained using a small-parameter expansion method. The well-known classical solution is the first approximation for the above-mentioned solution. A detailed numerical analysis has been carried out for isotropic and orthotropic shells. It is demonstrated that for isotropic shells of small and medium length the error of the classical solution is 10–20%, while the classical solution for orthotropic shell gives usually a larger error which may range up to 40%. __________ Translated from Problemy Prochnosti, No. 3, pp. 17–28, May–June, 2008.