任意旋转壳的振动特性计算

本文由旋转薄壳的基本方程导出了一组等效的一阶微分方程,并采用离散变量法对其进行求解。对于子午线出现尖角及双层旋转壳相耦合的情况,推导了相应的计算公式。文末给出了算例。     

Determination of the kinetic curves of drying of blocks of adsorbents-dessicants with different cross sections of channels and of a granulated adsorbent on a change in the flow velocity

The kinetics of convective drying (regeneration) of different types of adsorbents-dessicants with different geometric parameters has been studied. It is shown that adsorbents of a “channel” (cellular) type have a long constant-rate stage of drying, whereas a granulated polydisperse adsorbent is mainly dried at a variable rate. Adsorbents having a maximum water yielding capacity have been revealed. It has been established that the velocity of a drying gas flow substantially influences the process of moisture extraction from all types of adsorbents. In order to describe the kinetic curves of the given phenomenon, a model of a relaxation kinetic equation that quite satisfactorily describes the kinetics of drying of the adsorbents studied was used. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 65–68, January–February, 2009.     

Analysis of the sensitivity properties of a model of vector-borne bubonic plague.

Model sensitivity is a key to evaluation of mathematical models in ecology and evolution, especially in complex models with numerous parameters. In this paper, we use some recently developed methods for sensitivity analysis to study the parameter sensitivity of a model of vector-borne bubonic plague in a rodent population proposed by Keeling & Gilligan. The new sensitivity tools are based on a variational analysis involving the adjoint equation. The new approach provides a relatively inexpensive way to obtain derivative information about model output with respect to parameters. We use this approach to determine the sensitivity of a quantity of interest (the force of infection from rats and their fleas to humans) to various model parameters, determine a region over which linearization at a specific parameter reference point is valid, develop a global picture of the output surface, and search for maxima and minima in a given region in the parameter space.     

陶瓷材料压痕韧性的统计性质

采用直接压痕法测定了钠钙硅酸盐玻璃和一种ＴｉＣ 颗粒增强Ａｌ_２Ｏ_３复合材料的断裂韧性．研究表明,在同一压痕压制荷载下测得的同一种材料的压痕韧性呈现出较大离散性,可以采用Ｗｅｉｂｕｌｌ分布加以较好地描述．对两种材料的试验数据的对比分析指出,压痕韧性测试值的离散性反映了材料显微结构的不均匀性对材料局部裂纹扩展阻力的影响．基于这一分析,本文建议采用直接压痕法测定材料断裂韧性时,应尽可能增大试验量,从而对压痕韧性测试结果的统计性质作出完整描述．     

Prediction of Performance of an Industrial Poittemill in Production of Limestone Powders

Experimental data were collected from tests using an industrial-scale high-pressure roller mill named the Poittemill grinding limestone materials for a range of parameters (such as force pressure, circumferential speed of roll, and feed size) in a Nordkalk AB plant located in Ignaberga, Sweden. These data were used to develop models of throughput, size reduction, and energy utilization with the parameters. A performance model with a correction coefficient, which has been developed, is able to describe the Poittemill throughput at various force pressures and circumferential speeds of rolls. The materials leaked beside the rolls are found to be empirically related to the circumferential speed of roll in a given force pressure. It is shown that two major parameters, force pressure and circumferential speed of roll, have an influence on the median size (d₅₀) of the ground product. Product fineness is decreased at a higher circumferential speed of roll or at a lower force pressure. The force pressure is the most dominant effect on energy utilization in the mill. The feed size used has a slight influence on the grinding results. Energy to the Poittemill for the comminution is utilized more efficiently at a lower force pressure or a higher circumferential speed of roll. Empirical models can predict the comminution characteristics with respect to the major parameters in the Poittemill system in dry mode. Product size-energy input relations have been also established, independent of the operating parameters used.     

Application of causality check and of the reduced variables method for experimental determination of Young''s modulus of a viscoelastic material

An accurate determination of the complex dynamic Young's modulus of a viscoelastic material, in a broad frequency range, is presented in this paper. Curves of Young's modulus of the tested material (a mixture of polypropylene and calcium carbonate), at different temperatures, are experimentally obtained by means of a laser sensor. The experimental curves are then gathered into a unique master curve, by applying the reduced variables method and a causality check on the curves. The master curve represents Young's modulus of the viscoelastic material over a much broader frequency range, with respect to the range of a single experimental curve.     

Development of a Magnetic Suspension Densimeter and Measurement of the Density of Toluene

The development of a magnetic suspension densimeter that has been built for measurement of the density of compressed liquid at pressures up to 30 MPa in the temperature range 20 to 150°C is described. The densimeter was first built by the author and his coworkers at NIST. We describe here further improvements made on a second system built at NMIJ based on the same principle. The densimeter uses a small coil suspended from an electronic balance. Within the coil is placed a sample cell in which the pressurized sample and a buoy, which is a permanent magnet, are enclosed. For measurement of density, balance readings are recorded (1) with the buoy at rest and (2) with the buoy in magnetic suspension. The measurement procedure is basically a hydrostatic weighing, which is simpler than those of conventional magnetic densimetry. As an example, measurements of toluene density performed as part of an inter-laboratory comparison are presented. The data agreed with reliable literature values to within a few hundredths of a per cent.     

Accuracy improvement of T-history method for measuring heat of fusion of various materials

T-history method, developed for measuring heat-of-fusion of phase change material (PCM) in sealed tubes, has the advantages of a simple experimental device and convenience with no sampling process. However, some improper assumptions in the original method, such as using a degree of supercooling as the end of latent heat period and neglecting sensible heat during phase change, can cause significant errors in determining the heat of fusion. This problem has been improved in order to predict better results by us. The present study shows that the modified T-history method is successfully applied to a variety of PCMs such as paraffin and lauric acid having no or a low degree of supercooling. Also it turned out that selected periods for sensible and latent heat do not significantly affect the accuracy of heat-of-fusion. As a result, the method can provide an appropriate means to assess a newly developed PCM by a cycle test even if a very accurate value cannot be obtained.     

Adiabatic description of superfocusing of femtosecond plasmon polaritons

A surface plasmon polariton is a collective oscillation of free electrons at a metal–dielectric interface. As wave phenomena, surface plasmon polaritons can be focused with the use of an appropriate excitation geometry of metal structures. In the adiabatic approximation, we demonstrate a possibility to control nanoscale short pulse superfocusing based on generation of a radially polarized surface plasmon polariton mode of a conical metal needle in view of wave reflection. The results of numerical simulations of femtosecond pulse propagation along a nanoneedle are discussed. The space–time evolution of a pulse for the near field strongly depends on a linear chirp of an initial laser pulse, which can partially compensate wave dispersion. The field distribution is calculated for different metals, chirp parameters, cone opening angles and propagation distances. The electric field near a sharp tip is described as a field of a fictitious time-dependent electric dipole located at the tip apex.     

Analysis of the Accuracy of Methods for the Direct Measurement of Emissivity

Emissivity measurements are of great interest for both theoretical studies and technological applications. Emissivity is a property that specifies how much radiation a real body emits as compared to a blackbody. The emissivity determination of a sample should be an easy task: a simple comparison between the sample and blackbody radiation at the same temperature. Unfortunately, when measuring the emissivity, some practical problems arise due to the differences between the true emitted radiation and the detected quantity. To clarify this point, an analysis of different direct methods for emissivity measurement is presented. Furthermore, a method that includes multiple reflections is developed. The systematic errors associated with each method are computed theoretically as a function of wavelength, sample temperature, and emissivity, and the surrounding enclosure temperature and emissivity. In general, the error is very high for small sample enclosures, but it strongly decreases when the enclosure area increases. Although at short wavelengths all the analyzed methods produce similar errors, noticeable differences appear under other conditions, and methods considering more radiation terms do not always produce lower errors.     

Model of directed crystallization of binary alloy

We consider a model of directed crystallization. We write the boundary-value problem to a curvilinear coordinate frame attached to the interface. The theory of perturbations is formulated for small perturbations of temperature and component concentration. We study stability of the interface of a binary alloy. In this paper, we show the manner in which the known phenomenon of the lamination of the components in a melt, result in formation of regular eutectic structure. We also give a conclusion of analytical expression for period of this structure.     

Slepian simulation of distributions of plastic displacements of earthquake excited shear frames with a large number of stories

The object of this study is a stationary Gaussian white noise excited plane multistory shear frame with a large number of rigid traverses. All the traverse-connecting columns have finite symmetrical yield limits except the columns in one or more of the bottom floors. The columns behave linearly elastic within the yield limits and ideally plastic outside these without accumulating eigenstresses. Within the elastic domain, the frame is modeled as a linearly damped oscillator. The white noise excitation acts on the mass of the first floor making the movement of the elastic bottom floors simulate a ground motion that interacts with the structure above the bottom floors. As in a recent work by the authors, the paper is about application of the so-called Slepian model simulation, but in this paper supplemented by a simplification principle that allows a manageable calculation for the considered type of elasto-plastic oscillator also when it has a large number of elasto-plastic columns.     

Intensification of vibration mixing of particulate solids by means of multi-layer loading of components

The objective of the study is to show how initial distribution of dissimilar particulate components influences the mixing time and mixture quality. The dissimilar components have a tendency to segregate in one another, and it is impossible to achieve the perfect mixture of them in industrial settings. Nevertheless, the situation can be improved if the components are loaded as a sequence of several sandwiches, each of these sandwiches containing layers of components that are proportional to their share in the mixture. In this case, a sort of pre-mixing occurs while still at the loading stage – which allows reducing the optimum mixing time and increasing the homogeneity of the mixture. The theory of Markov chains was used to simulate the mixing kinetics. It is shown that the number of loaded sandwiches has a very strong influence on the process efficiency. A loading device that can effectively realize multi-layer loading is proposed. The mixing kinetics for ternary mixture of glass beads was investigated experimentally at a lab scale vibration mixer. A one-time loading and a two-sandwich loading were compared. It was shown that the optimum mixing time and non-homogeneity of the mixture were reduced by half in the latter case.     

Effects of particle size of reactant on characteristics of combustion synthesis of TiC-Fe cermet

Four Ti-C-Fe powder mixtures, with a same molar ratio but a different particle size, were used for a combustion synthesis of TiC-Fe cermet to investigate effects of the particle size on the characteristics of the combustion synthesis. The results showed that the mixture with the finer Ti powder gave out a higher combustion temperature, a higher reaction velocity, a higher product density, a layer-shaped pore, and a greater size of TiC particles whether the Fe powder was finer or coarser. While in the case of the coarser Ti powder used, a small amount of residual phase remained in the product, and what is more interesting that the mixture with the finer Fe powder gave out a lower reaction velocity than that by the mixture with the coarser Fe powder. These effects were successfully explained with the previously proposed mechanisms of the combustion synthesis of TiC-Fe, and the mechanisms were proved to be valid thereby.     

Experimental evaluation of the interference method of measurement of displacements on the basis of illumination of the surface of a test object

Results from experimental studies of a laser displacement measurement device that implements a new interference method of measurement based on illumination of the surface of a test object are presented. Translated from Izmeritel’naya Tekhnika, No. 10, pp. 26–30, October, 2008.     

Recent development and prospect of electromagnetic processing of materials

Application of electromagnetic force to materials processing, so called Electromagnetic Processing of Materials (EPM) has been recognized as a cutting edge technology, especially in the fields of advanced materials processing. The backgroundto promote EPMis described. The present state of EPMis given through a brief introduction of several examples of the applications of a high frequency magnetic field, a DC magnetic field, DC magnetic and electric fields, and a traveling magneticfield. Furthermore, a high static magnetic field has been applied to generate compression waves in molten metals. As otherexamples of the application of a high static field, the crystal orientations in thin films in vapordeposition and electrodeposition processes and those in carbon fibers in a graphitization process are described. Finally the future view of EPM is revealed.     

Graphitization of inner surface of copper beam duct of KEKB positron ring

In order to evaluate the best technique to reduce electron cloud instability, we measured the electron cloud density in copper ducts coated with titanium nitride and non-evaporable getter used in the KEK B-factory (KEKB) positron ring. In this study, we developed a new system for the graphitization of copper beam ducts. The graphitization of a copper surface by intense electron bombardment resulted in the reduction in the secondary electron yield (SEY) to 1.0 in a laboratory experiment and to 1.1 in a real beam duct. The electron cloud density in the graphitized duct is 30% lower than that in an uncoated copper duct. Thus, it has been confirmed that the graphitization of a beam duct leads to a reduction in the electron cloud density in the duct.     

The solution of the inverse problem of gravitational potential using a set of measurements of different field elements

A numerical solution of the inverse problem of the gravitational field at a single point is obtained using six field elements for a point, a spherical cap, a differential spherical sector and a vertical segment. In the system of six equations obtained, the unknowns are the mass of the body, the depth of its center, and the second, third, and fourth degree moments. The accuracy of the solution of this system is ten times higher than when using three field elements. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 3–8, May, 2007.     

Analysis of a number of elements in the mechanism of mass entrainment of carbon material within the framework of the complete thermochemical model of its destruction

The results of a numerical solution of the equations constructed for a frozen boundary layer on the surface of a carbon material, with allowance for the complete thermochemical model of the entrainment of its mass, are presented. The results obtained are compared with the data that correspond to the use of the analogy between the processes of heat and mass transfer in a boundary layer and of the simplified model of the mass entrainment of the materials of the class considered. The results of comparison between experimental and calculated-theoretical data on the rate of destruction of the ATJ-grade graphite are also presented. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 127–133, January–February, 2009.     

干式变压器生产过程的工作研究

通过流程程序分析，对干式变压器生产过程中存在的重复、迂回和多余的内容进行了合并、简化或者取消，优化了生产工艺过程；通过操作分析和动作研究，对套装和叠铁等以手工操作为主的工序进行了改进，制定了标准操作法；通过时间研究，制定了各工序较为科学合理的时间定额。改进后，公司在不增加人员和设备的情况下，产品产量增加近1/3。