空分设备加温流程的优化与应用

介绍了兖矿鲁南化肥厂3套空分设备停车加温流程存在的问题,针对3套空分设备的特点,充分利用资源,将其加温流程连通改造。改造投用后经济效益明显,达到了资源互补、节能降耗的目的。     

加热方式对渗透汽化过程的影响

利用渗透汽化平板膜浓度剖面和温度剖面的计算模型对乙醇脱水进行了模拟计算,计算了外源不加热,恒温加热,恒功率加热,恒温差级间加热和恒膜面积级间加热5种加热方式对水浓度剖面和温度剖面的影响,并比较了不同方式所需的单位面积加热功率,结果表明,当料液中水含量较高时,外源加热是必须的;一般地讲,恒温加热和恒功率加热较级间加热和恒功率较级间加热所需的膜面积小,但单位面积的加热功率相对较大。     

On the numerical treatment of initial strains in biological soft tissues

In this paper, different methodologies to enforce initial stresses or strains in finite strain problems are compared. Since our main interest relies on the simulation of living tissues, an orthotropic hyperelastic constitutive model has been used to describe their passive material behaviour. Different methods are presented and discussed. Firstly, the initial strain distribution is obtained after deformation from a previously assumed to be known stress‐free state using an appropriate finite element approach. This approach usually involves important mesh distortions. The second method consists on imposing the initial strain field from the definition of an initial incompatible ‘deformation gradient’ field obtained from experimental data. This incompatible tensor field can be imposed in two ways, depending on the origin of the experimental tests. In some cases as ligaments, the experiment is carried out from the stress‐free configuration, while in blood vessels the starting point is usually the load‐free configuration with residual stresses. So the strain energy function would remain the same for the whole simulation or redefined from the new origin of the experiment. Some validation and realistic examples are presented to show the performance of the strategies and to quantify the errors appearing in each of them. Copyright © 2006 John Wiley & Sons, Ltd.     

Quasistationary temperature stresses in multiply connected plates in the process of heating

We present an algorithm for the evaluation of quasistationary temperature stresses in multiply connected plates with heat transfer heated by heat sources. For the solution of the problem, we use the Laplace transformation, improved formulas of its numerical inversion, and the method of integral equations. We present several examples of the numerical evaluation of nonstationary temperatures and temperature-induced stresses in plates of various shapes. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 42, No. 6, pp. 27–33, November–December, 2006.     

Contact atomic force microscopy of biological tissues

The forces of adhesion of the normal and tumor cells of the human stomach epithelium to the probe of an atomic force microscope have been measured for the first time. It is established that the adhesion and contact stiffness of malignant cells are significantly lower than those of the normal cells.     

Thermal model of local ultrasound heating of biological tissue

Possibilities of creation of controlled temperature fields in deep-seated biological tissue with the use of an endocavity ultrasound applicator with surface cooling are considered. Mathematical models are proposed and calculated that make it possible to construct acoustic and thermal fields in biotissues depending on the thermophysical and ultrasound characteristics of the medium being irradiated and to reveal situations and effects that are important for solving problems of practical medicine in the field of local ultrasound hyperthermia and thermotherapy of tissue. Kiev Polythechnical Institute, Kiev, Ukraine. Institute of Experimental Pathology, Oncology, and Radiobiology, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 5, pp. 779–784, September–October, 1996.     

Measurement and simulation of light distribution in biological tissues

Lateral light-distribution images of biologic tissues were used to study the tissues' optical characteristics. Monte Carlo simulation with the same conditions was performed to simulate the light distribution for comparison. Simulation results showed that the lateral light distribution was similar to the internal light distribution in biologic tissue. The direction of muscle fibers and the temperature both affect the near-field light distribution in tissue. The lateral view distribution can be both measured and simulated to study photon migration in tissue. It can also be used to estimate or verify the optical coefficients of tissue.     

Frequency doubling of ultrashort laser pulses in biological tissues

Theoretical and experimental studies of second-harmonic generation (SHG) in biological tissues was performed by use of ultrashort laser pulses (<1 ps). A simplified one-dimensional model for the generation and the propagation of frequency-doubled light inside tissue was developed. This model was tested in vitro against measurements of pig and chicken tissue and human tooth. The experimental results indicate that the intensity of SHG varies significantly among tissue types and between test sites in individual tissue. Possibilities of using this nonlinear tissue property in imaging and diagnostics are discussed.     

Simulation of the temperature field in the surface layer under pulsed electron-beam heating

This paper presents the results of the numerical simulation of the temperature field in single-and double-layer materials under electron-beam heating in stationary and pulsed modes and analyzes the conditions under which control of the heat-treated-layer parameters by varying the duration, the off-duty ratio, and the number of heating pulses is provided. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 2, pp. 20–24, March–April, 2007.     

The microscopic nonequilibrium process in solids under transient heating

A brief review of studies on the dynamic process of thermal expansion since the eighties is given. A magnitude of difference of one to two orders between the results of theoretical calculations and experimental observations of the characteristic time is discussed. The nonequilibrium localized phonon gas in a “hot spot” is studied using the Boltzmann equation, leading to a soliton-like solution. It gives the way to fill the gap of the above-mentioned difference between theory and experiment. The lattice relaxation of a laser rod is developed theoretically and verified experimentally. Different expansion processes of a high-T _c superconductor below and aboveT _c imply the existence of some new features of excitons in the high-T _c state. Keynote lecture presented at the Fourth Asian Thermophysical Properties Conference, September 5–8, 1995, Tokyo, Japan.     

陶瓷加热圆棒瓷体强度工艺探究

本文通过对一种可用于电子恒温器、空调机辅助加热、热吹风、汽车尾气处理器等领域,军民两用的新型发热元件—陶瓷加热圆棒瓷体强度的关键技术流延浆料的分散、烧结等工艺的介绍和分析,对影响陶瓷加热圆棒瓷体强度的难点和关键点做出了说明和探究。     

Light propagation in biological tissues containing an absorbing plate

We study light propagation in biological tissue containing an absorbing obstacle. In particular, we solve the infinite-domain problem in which an absorbing plate of negligible thickness prevents a portion of the light from the source from reaching the detector plane. Inasmuch as scattering in the medium is sharply peaked in the forward direction, we replace the governing radiative transport equation with the Fokker-Planck equation. The problem is solved first by application of the Kirchhoff approximation to determine the secondary source distribution over the surface of the plate. That result is propagated to the detector plane by use of Green's function. The Green's function is given as an expansion of plane-wave modes that are calculated numerically. The radiance is shown to obey Babinet's principle. Results from numerical computations that demonstrate this theory are shown.     

Simultaneous determination of thermal characteristics for disperse materials in the process of heating

A relative method is proposed for the direct determination of the set of thermal characteristics for the free-flowing masses of materials in the process of heating, said method based on the application of the principle of a diathermic shell.     

Time-gated transillumination of biological tissues and tissuelike phantoms

The applicability and limits of time-resolved transillumination to determine the internal details of biological tissues are investigated by phantom experiments. By means of line scans across a sharp edge, the spatial resolution (Δx) and its dependence on the time-gate width (Δt) can be determined. Additionally, measurements of completely absorbing bead pairs embedded in a turbid medium demonstrate the physical resolution in a more realistic case. The benefit of time resolution is especially high for a turbid medium with a comparatively small reduced scattering coefficient of approximately μ(s)' = 0.12 mm(-1). Investigations with partially absorbing beads and filled plastic tubes demonstrate the high sensitivity of time-resolving techniques with respect to spatial variations in scattering or absorption coefficients that are due to the embedded disturber. In particular, it is shown that time gating is sensitive to variations in scattering coefficients.     

Improvement in the resolving power of impedance thermo- and tomography of biological tissues

We analyzed the possibility for measuring the temperature of the internal structures of a body by using low-frequency currents. We show ways for solving the problem of the limited resolving power of the impedance thermo- and tomography method and present the results of the experiments conducted. National Technical University, Kiev, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 3, pp. 467–471, May–June, 1996.