Targetry for the cyclotron production of short-lived radionuclides for medical use

Solid, liquid and gas targets for the production of short-lived radionuclides for medical use are discussed: liquid and gas targets have important advantages compared to solid targets. Target systems for the production of ¹¹C, ¹³N, ^15O, ³⁸K and ⁸¹Rb and the experimental optimization of gas target systems are described.     

Numerical solution for the steady-state coefficients of the inverse heat-transfer problem for stratified media

Problems of the uniqueness of the inverse heat transfer problem for stratified media are considered and algorithms for computing approximate solutions are discussed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 3, pp. 509–513, March, 1989.     

Simple technique for increasing the conductivity of copper for current lead conductors

Current leads are used mainly as conductors for electrical current to be supplied to superconducting magnets. Low liquid helium losses in the current leads are of great importance and therefore the geometry of the current lead must correspond to a specific optimized current. Here it is shown that, by altering the residual resistivity of the conductor material, one can modify the optimized current of the current lead without changing its original geometry. A relatively easy technique for decreasing the resistivity of commercial electrolytic tough-pitch copper is described. Experimental results of copper annealing in a vacuum of 2.7 × 10⁻³ Pa (2 × 10⁻⁵ torr) in the temperature range of 295–703 K are discussed.     

Some Grubbs-Type Statistics for the Detection of Several Outliers

Several widely used tests for outlying observations are reviewed. Problems of repeated application and “masking” are described. Suggested as appropriate to over-come these problems are two new statistics: L_k which is based on the k largest (observed) values and E_k which is based on the k largest (in absolute value) residuals. Tables of approximate critical values for these statistics are given for 0.01, .025,0.05, and 0.10 levels of significance and for sample size n = 3 (1) 20 (5) 50.     

Primary Radiometry for the Mise-en-Pratique for the Definition of the Kelvin: The Hybrid Method

A task group of CCT-WG5 (radiation thermometry) was established in May 2008 to write text for the mise-en-pratique for the definition of the kelvin (MeP-K) for high temperatures. This task group reviewed and gave summaries for the existing techniques for filter radiometry as a means of determining the absolute radiance, and hence the thermodynamic temperature of a blackbody source. Three approaches were described??the radiance method, which calibrates the radiation thermometer for radiance responsivity, the irradiance method, which calibrates a filter radiometer for irradiance responsivity and then measures the source through two apertures, and the hybrid method that introduces a lens to the irradiance method. In the ??hybrid method?? the radiation thermometer consists of a filter radiometer, a double aperture system, and a lens. The lens allows the instrument to view a small area blackbody source. The system is calibrated ??in parts????i.e., the filter radiometer is calibrated for irradiance responsivity, and the transmittance of the lens and the geometric factor are determined separately. The main drawbacks of this single lens instrument are its high size-of-source effect (~0.2 %), and that this effect has to be determined in an ??absolute?? sense??relative to a theoretical infinite source. However, although the correction is large, with careful evaluation, the associated uncertainty can be made sufficiently small to measure the temperature of fixed-point cell transitions with low uncertainties. This article reviews the hybrid method and gives a comprehensive discussion of the associated uncertainty components.     

Criteria for the Evaluation of Photographic Lenses

Simplified test conditions for the evaluation of lenses based on MTF measurements are described, and criteria for interchangeable lenses for 35 mm cameras are proposed. Measurements are to be made for white light, at the infinite conjugate plane, on axis and at 0·7 field (15 mm off axis) positions, at full aperture and ?/5·6. The focus is to be adjusted at each aperture so as to give the best MTF response at 30 lines/mm on axis. The MTF responses at 15 and 30 lines/mm are to be examined for the evaluation of the lenses. Simple criteria based on the experimental data for about 100 different types of interchangeable lenses are proposed.     

A new method for the numerical solution of the Reynolds equation for gas-lubricated slider bearings

Summary The steady-state Reynolds equation for gas lubricating leads to a quasilinear boundary-value problem in two dimensions. This equation contains a first-order derivative term whose coefficient is nonlinear and also large for most of the practical cases. Thus, this becomes a quasilinear singular perturbation problem. Existing numerical schemes are faced with the failure of convergence as well as numerical instability which often results in overshooting the answers. Asymptotic approximations also give poor results if the film-thickness ratios are not small. In this paper an accurate and reliable numerical scheme is presented. Convergence is proved independent of the bearing numbers and film-thickness ratios. A weighted upwind-difference form is used to discretize the differential equation. Theory of M-matrices and associated inequalities are employed to prove the ensuing monotonicity. The analysis presented in this paper can be extended to a more general class of singular-perturbation quasilinear boundary-value problems. Numerical results and graphs for pressure distributions and bearing loads are provided for the parabolic slider. Comparisons are made with other existing results concerning numerical as well as asymptotic analysis.     

Electrode materials for the photoelectrolysis of water

There has recently been a renewed interest in photoelectrochemical processes at semiconductor-electrolyte interfaces for possible applications in solar conversion. In particular, the photoelectrolysis of water by sunlight in electrochemical cells to produce the fuel H₂ has resulted in considerable research. In this paper, the concepts of photoelectrolysis are used as a guide for deriving the physical and chemical properties necessary for materials to be efficient electrodes in such cells. Presently available materials are considered in this context along with prospects for the future.     

Methods for the detection of changes of interference order for interference refractometers

Conventional methods for detecting the fractional and integer parts of an interference order are described, and they are subjected to a comparative analysis from the standpoint of precision, reliability, and speed of acquisition of measurement data. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 20–26, May, 1995.     

Theory for Optimal Test Plans for the Random Fatigue-Limit Model

This article presents methodology for planning life tests based on the random fatigue-limit model (RFLM). The RFLM describes the relationship between fatigue life and the applied load in the presence of fatigue limits. A standardization of the RFLM is presented, and corresponding expressions for the elements of the Fisher information matrix are given. Different test plan criteria that express various objectives that the practitioner may have in conducting experiments under the RFLM are discussed. These criteria include estimation of life quantiles, estimation of stress/strain levels that yield a specific life quantile, estimation of fatigue-limit quantiles, and D and D_s optimality. Equivalence theorems used to verify optimality of test plans are also presented. The methods are sufficiently general so they can be applied to criteria based on any function of the model parameters. They are demonstrated using a nickel-base superalloy experiment.     

Dynamical criteria for reproducibility of the structure of solid materials

Reasons for the irreproducibility of the structure of solid materials grown under the same technological conditions are examined. Dynamical criteria for irreproducibility are developed, and a fundamental limit on the irreproducibility and its dependence on the dimensions of the system are determined. Pis’ma Zh. Tekh. Fiz. 23, 81–84 (October 12, 1997)     

The Roles of the Mise en Pratique for the Definition of the Kelvin

The mise en pratique (“practical realization”) for the definition of the kelvin (MeP-K) was created by the Consultative Committee for Thermometry (CCT) in 2006 to give practitioners of thermometry a guide to the realization of the kelvin, i.e., measurement of temperature in kelvins, in accord with the International System of Units. In this article, the present and the future content of the MeP-K, the relationship of the MeP-K to other documents relevant to thermometry, the categorization of thermometry techniques in the MeP-K, and the benefits of proposed additions to the 2006 version of the MeP-K are discussed. The three categories of measurements within the MeP-K are: (1) primary methods for measuring thermodynamic temperature T; (2) formal approximations to T, in particular, the International Temperature Scale of 1990 (ITS-90) and the Provisional Low Temperature Scale from 0.9 mK to 1 K (PLTS-2000); and (3) indirect approximation methods that are neither primary nor defined on a temperature scale, yet capable of exceptionally low uncertainties or increased reliability. By providing a framework for primary methods and indirect methods, the MeP-K will foster development and application of new methods, such as the use of absolute radiometry or high-temperature fixed points. The MeP-K provides the CCT with a mechanism to update and to expand the thermometric methods in common use, without imposing on industry the high costs of changing the International Temperature Scale.     

Confidence intervals for the comparison of variability estimates for a mixed model

In this paper, we develop methods for generating confidence intervals for the comparison of variability estimates in a mixed‐effects model. A generalized confidence interval (GCI) is developed and contrasted to the modified large sample (MLS) method with an adjustment for a fixed effect. The methods are assessed using a computer simulation. Recommendations are provided for selecting an appropriate method. Copyright © 2007 John Wiley & Sons, Ltd.     

Microprocessor instruments for measuring nonlinear distortions; algorithms for digital processing of the measurement signal and an estimate of the errors

Rational algorithms for measuring the harmonic coefficient in microprocessor instruments for measuring nonlinear distortions based on digital processing of the codes of the instantaneous values of the signal being investigated are described and the errors of such instruments are obtained.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 56–59, April, 1995.     

A Chebyshev collocation method for computing the eigenvalues of the Laplacian

Chebyshev collocation techniques are developed in this paper to compute the eigenvalues of the Laplacian based on a boundary integral formulation for two-dimensional domains with piecewise smooth boundaries. Unlike the traditional domain methods (for example, the finite element method) which discretizes the eigenfunctions on the two-dimensional domain, only a one-dimensional function defined on the boundary is discretized. Global expansions in terms of Chebyshev polynomials are used in each smooth piece of the boundary to solve the integral equation. Comparing with the boundary element method, this method obtains higher accuracy for a smaller discretized matrix. Finally, an efficient algorithm for generating the discretized matrix (say, n × n) is developed that requires only O(n² log n) operations.     

An improved technique for the solution of edge crack problem for finite plate

This paper provides a detailed examination for the edge crack problem of finite plate. The Williams expansion for the crack problem is used first. Secondly, the complex potentials for the central crack problem are used in the present study, which is called the improved technique hereafter. In both techniques, the eigenfunction expansion variational method (EEVM) is used for evaluating the undetermined coefficients in the expansion form. The ratio of height versus width of plate (h/w) is varying from 1.5, 1.0, 0.75, 0.5, 0.4, 0.3 to 0.25. The ratio of edge crack length versus width of plate (a/w) takes two sets: (1) a/w = 0.1, 0.2, … to 0.9, (2) a/w = 0.01, 0.02, … to 0.09. The detailed computation proves that for moderate cases of the a/w ratio, for example, 0.2 < a/w < 08, the deviations for SIFs and T-stress from two techniques are minor. However, for the case of short edge crack length, for example, a/w < 0.05, the deviations for SIFs and T-stress from two techniques are significant. It is found that the Williams expansion may not be suitable for the short edge crack, for example, a/w < 0.05.     

Spectral-ratio pyrometer for measuring the temperature of carbon steels

The salient features of a spectral-ratio pyrometer for measuring the true temperature of metal steam pipes in the range from 700 to 1100°C are considered. Experimental data on the monochromatic emissivity of a carbonsteel surface during oxidation at 1000°C are given. Optimal spectral regions are chosen for a spectral-ratio pyrometer, the pyrometer is described briefly, and the results of tests with the instrument are reported. Translated from Izmeritel'naya Tekhnika, No. 2, pp. 23–25, February, 1997.     

On the use of the Goodman diagram for high cycle fatigue design

Materials in rotating machinery are typically subjected to vibratory loading from a number of sources which, in turn, is superimposed on mean stresses which result primarily from steady-state centrifugal loads. In addition, components subjected to vibratory stresses can sustain damage during manufacturing, break-in cycles, or during service such as from foreign objects, fretting, or other types of wear. The combination of vibratory and ‘steady’ stress levels can, for certain load levels, produce low cycle fatigue damage in addition to the damage produced from the high frequency (HCF) vibratory loading since the ‘steady’ stresses are actually low cycle fatigue (LCF) which results in one cycle for every startup and shutdown operation. Design for HCF is generally based on a Goodman diagram which takes into account the vibratory as well as the steady stress amplitudes for fatigue runout or fatigue under a given number of cycles. It does not, however, take into account the combined effects of LCF and HCF. In this investigation, the combined effects are demonstrated analytically by numerical examples which consider both the initiation and propagation phases of fatigue. In addition to the analysis of LCF/HCF interactions, considerations which must be accounted for in design are reviewed in light of a number of failures of components in service in U.S. Air Force fighter engines. A critical assessment of the concepts embedded in the use of the Goodman diagram is presented. Comments on the limitations on the use of a Goodman diagram for design are provided. Some suggestions are offered for the improvement of the design methodology for HCF which involve both damage tolerance considerations and methods for assessing and improving the margin of safety.     

Statistical Evaluation of the Results Obtained with the Analytical Methods used for the Quality Control of Medicines

Abstract

To improve the way by which the quality control of medicines is carried out, general statistical concepts and methods are discussed for the evaluation of the analytical results obtained for judging the adequacy of drug substances and products for Pharmacopoeia requirements.

Statistical procedures to be adopted by the producer and the controller in the determination of characteristics are suggested when the drug substance is or is not homogeneous and when the precision of the analytical method is known or unknown.

For each of these cases, detailed numerical examples are given.     

Two derivations of the Feynman formulae for the fields of a moving charge

Abstract

The Feynman expressions for the electric and magnetic fields of a charge moving on an arbitrary trajectory are found by two simple methods. The first involves a direct integration of Maxwell's time-dependent equations. The second is based on the formalism of quantum optics which uses the first order equations of motion for creation and annihilation operators. As an illustration of the simplicity of these methods, the fields of an oscillating electric dipole are obtained.