On the statistical estimation of the lifetimes of charmed particles

Various statistical methods for the estimation of the mean lifetimes of charmed particles have been considered. It is shown that the usual estimates of the maximum likelihood in some cases do not exist or may have rather great positive bias, if the statistics are low. Alternative estimates of the mean lifetime τ are discussed. Among them the “jackknife” estimate of τ is considered. The minimum variance unbiased estimates of the average rate of decay have been derived for some particular cases. It is also shown that the usual estimate of the ratio of the mean lifetimes of different kinds of particles may also have a bias when the statistics are poor. Two methods of reducing this bias have been proposed.     

Effect of deformations in the bending of the shaft on the accuracy of torque measurements

Summary The above experimental and theoretical investigations have shown that in order to compensate for the error produced by the bending of the shaft in measurements of torque by means of strain gauges it is necessary to fix the transducers in positions which have the smallest bending strains and place them in strict conformity with the relations deduced above.     

Prediction of the Temperature and Density Dependences of the Parameters of the Average Effective Binary Mixture Pair Potential Using Only the LIR Equation of State

Recently, using the linear isotherm regularity (LIR) equation of state, the average effective pair potential parameters for dense fluids have been calculated, and it was shown that they are only temperature dependent. Those parameters were used to propose a strong principle of corresponding states. In the present work, the approach is extended to binary mixtures, from which we have found that the average effective pair potential parameters of mixtures depend on composition and temperature. We have also calculated the average effective unlike pair potential parameters of mixtures at various temperatures via the LIR parameters. The calculated like and unlike pair potential parameters of some mixtures have then been used to calculate their excess enthalpy. When the calculated average effective pair potential parameters of mixtures are used to reduce the LIR parameters, a strong principle of corresponding states has been observed for various mixtures with different compositions, as for the pure components. The calculated like and unlike pair potential parameters have been tested with different mixing rules based on the one-fluid approximation. The maximum differences of the calculated values with the mixing rules are lower than 10%.     

Practical aspects of the application of the universal algorithm for testing statistical hypotheses

Recommendations on the application of the universal algorithm for testing statistical hypotheses for the solution of important engineering problems are given. The simple problem of testing hypotheses has been considered in detail, solution algorithms have been constructed, and their properties have been investigated. For the differential problem of matching two distributions, the metrics of estimating the difference between them have been analyzed. On the basis of the metrics, the properties of the tools of parameterization of a set of arbitrary empirical distributions have been considered.     

A method for the determination of the parameters of the hysteresismodel of magnetic materials

Many methods have been proposed for the determination of the hysteresis loops of magnetic materials, and many mathematical approaches have been proposed to find a good model for the hysteresis phenomenon. However, very few attempts have been made to determine the parameters of the hysteresis model experimentally. This paper shows how, starting from a digital method for the experimental determination of the hysteresis loop under different maximum induction values, the parameters of a hysteresis model can be automatically estimated with good accuracy. Due to its good behavior in terms of accuracy and to the comparative ease in determining its parameters, the Preisach model for rate-independent hysteresis phenomena was chosen. Experimental determination of the model and consequent hysteresis loop computation were carried out. An accuracy below 1% was attained over the peak induction range from 0.49 T to 1.68 T and the frequency range from 50 Hz to 100 Hz     

Modelling the glacial isostatic adjustment of the UK region

The glacial isostatic adjustment of the UK region has been considered in a number of recent studies. We have revisited this problem in order to: (i) highlight some key issues with regard to limitations in the ice modelling approach adopted in these studies and (ii) consider the constraints provided from observations of crustal motion available via continuous global positioning system monitoring. With regard to the first aim, we have found that: (i) previous studies have significantly overestimated ice thicknesses in regions where trim line field constraints were adopted and (ii) the duration of the glaciation phase of the UK ice sheet is a critical aspect of the model and that discrepancies in this model component have led to inconsistent inferences of Earth model parameters. With regard to the second aim, we have found that predictions of horizontal velocities (relative to a chosen site) based on a UK ice model calibrated to fit the regional sea-level database capture the geometry of the signal well but only account for 10% of the magnitude (for a range of Earth models).     

Errors in the measurement of the steady-state flow of heat at the surface of a body

We have undertaken an analysis of the distortions in the flow of heat in an object, said distortions attributable to the presence of a heat-metering thermometer, and we have derived formulas to estimate this measurement error.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 4, pp. 667–674, October, 1989.     

Optical performances of the Ultraviolet Coronagraph Spectrometer of the Solar Heliospheric Observatory

The optical performances of the spectrometer assembly for the Ultraviolet Coronagraph Spectrometer of the Solar and Heliospheric Observatory mission have been tested. The flight unit of the spectrometer assembly, consisting of the structure equipped with the entrance slits assembly, the grating drive mechanisms mounting two toroidal gratings, and the photon-counting detectors, has been integrated and aligned; also the flight unit of the White Light Channel has been integrated and aligned in the spectrometer assembly. Tests with both visible and UV radiation have been performed. Aberration and stray-light measurements have shown that the instrument performs satisfactorily, almost in compliance with the scientific requirements; also some measurements of the polarimeter modulation curve and the relative error have shown performances within the specified requirements.     

Thermodynamics of the infiltration of nanodispersed materials

Thermodynamic studies of the infiltration of porous bodies formed from macro- or nanoparticles have been conducted. Thermodynamic functions that describe the infiltration have been derived and the criteria for the conditions for spontaneous infiltration of the porous materials under study have been substantiated.     

体验材料的表现力、发掘创造性思维--在立体构成教学中对材料感受的拓展

在立体构成课的造型训练中，利用简单的基本材料的限制，开发学生的创造性思雏，使非专业人员看来平淡无奇、能力有限的常规材料，在专业设计者手中成为表现力无限的常新材料。     

硝基苯及其衍生物在石墨表面的组装结构和硝基位置的确定

利用STM研究了硝基苯及其衍生物N-十八烷基-(4-硝基-苯亚甲基亚胺)在石墨表面的组装结构．实验结果表明，利用硬脂酸作为缓；中层可以使硝基苯分子稳定地吸附在石墨表面，形成二维有序的单层，在这种硝基苯的有序单层上利用STM得到了具有原子级分辨率的图像，这一方法为在大气务件下用STM表征小分子提供了一种可能的策略．通过标记官能团的引入，证明在硝基苯及其衍生物的组装结构中，硝基与苯环上的氢原子形成了分子间氢键．并且确定了硝基官能团的位置和分子间的连接方式。     

Characteristics of the wear process in the cutting of free-cutting steels

The paper brings some interesting results of the investigation of the cutting edge wear at cutting of free cutting steels by cemented carbide plates. These steels are characterized by the additions of sulphur and lead to increase machinability. The experimental results have shown that the additives of sulphur and lead can strongly affect not only chip generation but also the form and rate of wear. Previous investigations have indicated clearly that the criterion of wear on the clearance faces provides too little information on tool life. The experimental results have also shown that at equal wear on the clearance face the form and rate of wear on the rake face differ essentially.     

Investigation of the effect of the Prandtl number on the local properties of low-intensity convection in a rectangular region heated from below

Local heat transfer and temperature separation in the presence of steady-state natural thermal convection in a rectangular region heated from below have been numerically studied for various Prandtl numbers. The local features of the low-intensity convection have been analyzed. The dependences of the local effects on the Grashof and Prandtl numbers have been obtained. The effect of the Prandtl number on the boundaries of the convection regimes has been estimated.     

On the effect of quench rate on the structure of amorphous carbon

We have simulated, via tight binding molecular dynamics (TBMD), the process of the quench from a melt of an atomic scale system of carbon. We have correlated the local properties of the resulting structure to the quench rate used to bring the liquid phase beyond the glass transition temperature. Results have been analyzed also in terms of the hamiltonian model used to describe the simulated system. In this respect, amorphous structures generated via tight binding and ab initio molecular dynamics have been compared. Results indicate that quench rates as slow as 10¹⁴ K/s produce the onset of an increasingly high fraction of threefold coordinated sites in the structure. Moreover, it has been put in evidence the tendency of the tight binding approach to favor threefold coordinated sites with respect to fourfold coordinated, even in the fast quench rates domain.     

Geometries With the Demagnetizing Energy Independent of the Direction of Magnetization

We have studied single-domain particles of nonellipsoidal shape and of uniform magnetization and have found that the demagnetizing energy is independent of the direction of magnetization in bodies with certain symmetries. Our study used several symmetries containing rotation or rotoinversion in the calculation of demagnetizing energies in various directions of axis     

Mixed Projection-Mesh Scheme of the Finite-Element Method for the Solution of Problems of the Elasticity Theory

A mixed projection-mesh scheme for solving the boundary-value problems of the elasticity theory has been formulated. Correctness and convergence of the mixed approximations for strains and displacements are studied. Application of the numerical integration has been analyzed, and the obtained results are given. The theory of generalized functions and the functional analysis methods have been used for the convergence and accuracy estimates. Iteration algorithms for solving the discrete problems have been proposed.     

A fracture mechanics approach for the prediction of the failure time of polybutene pipes

In this work two grades of Isotactic polybutene-1 with a different degree of isotacticity have been investigated; fracture tests have been performed at various temperatures and testing speeds on DCB and SENB samples. Optical methods have been used to record crack advancement.Results of the tests have been interpreted using the fracture mechanics framework; a time–temperature superposition scheme has been adopted to describe crack propagation behaviour over several decades of time-scale. An analytical model has been applied to predict the lifetime of pressurised pipes from experimental fracture data. There is good agreement between model predictions and experimental data obtained from full-scale tests on real pipes.     

Investigation of the thermomechanical properties of industrial refractories: the French programme PROMETHEREF

This paper summarises the work that has been done in the framework of the French programme PROMETHEREF. This programme was concerned with the thermomechanical properties at high temperature of two industrial refractories: fused-cast materials for glass melting and alumina castables for steel production. At high temperature, both materials exhibit creep, that has been characterised by tension, compression and bending tests. The microstructural mechanisms of deformation have been investigated and allowed the macroscopic viscoplasticity to be understood. Both types of materials exhibit damage processes that have also been characterised mechanically and microstructurally. The nature and the adhesion of the aggregates have been shown to have a great influence on the mechanical behaviour of the castables, as well as the continuous zirconia skeleton observed in high-zirconia fused-cast refractories by X-rays tomography.     

On the maximum of the vertical fall velocity of a homogeneous sphere whose radius changes by the exponential law

The extreme properties of the vertical fall of a spherical body whose radius decreases with time by the exponential law have been investigated. The conditions under which the fall velocity has a maximum have been found.