Fabrication of nanoporous TiO2 films through Benard-Marangoni convection

Fabrication of nanoporous TiO₂ thin films through Benard-Marangoni convection is reported. Variation of pore size and morphology in the sol-gel deposited metal-oxide films is investigated as a function of ambient humidity and air flow velocity during film drying, sol concentration, and addition of water/acid to the sol. Received: 8 August 2001 / Accepted: 18 August 2001     

Burnout Heat Transfer in Boiling under Conditions of Stepwise Heat Generation

The results of experimental investigations on the time of the onset of boiling crisis in nonstationary heat generation are presented. A standard working formula is suggested for determining the time of the onset of burnout heat transfer in a wide range of heat loads, subcoolings, and pressures.     

An Oscillating Boundary Temperature Method for the Determination of Transient Thermal Conductivity and Internal Heat Generation with a Comparison to a Transient Hot-Wire Method

An oscillating boundary temperature (OBT) method is proposed to simultaneously determine transient thermal properties including thermal conductivity, thermal diffusivity, internal heat generation, and volumetric heat capacity for exothermic solids and semi-solids over a narrow, controlled temperature range by using internal temperature measurements of the thermal wave. A comparison of this method and a transient hot-wire (THW) method is conducted in the presence of heat generation using physical properties which change over time. The advantages and disadvantages of both methods are discussed. The OBT method is potentially useful for the analysis of exothermic solid or semi-solid materials such as hydrating (freshly mixed) cement and concrete, polymers and composites undergoing polymerization reactions, and biological tissues.     

Problems of Heat Conduction for an Angular Region with an Internal Source

Exact solutions of nonstationary problems of heat conduction have been obtained for an unbounded rectangular region when the opening angle is equal to /(2n + 1), where n is any natural number. By passage to the limit it has been shown that no stationary regime is possible for the rectangular region in the case of action of a constant internal source. The exact solution of the stationary problem for an angular region with an arbitrary opening angle ₀ has been given. It has been proved that in the presence of a constant heat source the stationary regime is possible just for the acute angle ₀ /2, while for the right or obtuse angles ₀ /2 the stationary regime is impossible, since the temperature increases without bound at internal points.     

Generation of Ripple-Size Internal Waves on a Fluidized Seafloor

Ripples produced on a fluidized seafloor have been observed in the field as well as in the laboratory. Because of their dynamic properties, they are sometimes referred to as transitional or ephemeral ripples, as they have been observed to go through cycles of forming and disappearing on the time scale of an individual wave period. The ripples also appear to go through a complex evolutionary sequence, occasionally leading to the spectacular event of sediment bursting from the seafloor. During bursting, loads of fluidized sediment will be ejected upward into the water column – in the form of intense sand plumes. Reproducing these ripples in the laboratory revealed that these ripples are actually a standing subharmonic internal wave on the water-sediment interface, produced by the water wave propagating above through an instability mechansim. In this paper an inviscid theory for the initial excitation of these dynamic ripples on a fluidized seafloor is presented.     

具有内外流的换热器管束动特性分析

利用大型有限元程序Ansys的参数化设计语言（APDL），对模型进行智能化网格剖分、材料参数设定、模型几何参数设置，完成了充满液体单管的建模和多种节径比的正方形排列管束的建模，并采用流固耦合法进行了动特性的计算。通过计算结果分析，得出了一些有价值的结论，可供从事换热器等化工设备设计的工程技术人员参考。     

Photon-Assisted Heat Generation in a Quantum Dot Device with the Charging Effect

Electrical current induced heat generation through an ultrasmall quantum dot–leads coupled system under AC fields is investigated by employing the nonequilibrium Green’s function technique. The external AC fields, charging energy and junction capacitances influence the heat generation sensitively. We find negative differential heat generation in our system. The reason for this is the Coulomb interaction, and the negative differential heat generation becomes larger as the frequency of AC fields $\omega $ increases. In addition, the peak caused by charging energy in $Q{/}\omega _0$ curve increases with $\omega $ rapidly. A region in which the value $Q{/}I$ is low emerges due to the charging effect. It is an ideal region for device operation. This region will enlarge as the parameter $R$ and the charging energy $E_c$ increase.     

具有外热阻内摩擦和冷头热漏制冷机的最大制冷系数

采用有限时间热力学研究了传热热阻，内部摩擦和冷头热漏三种不可逆损失对制冷机最优性能的影响。导出具有传热热阻，内部摩擦和冷头热漏不可逆损失的不可逆卡诺制冷机的最大制冷系数。     

External and Internal Knowledge in the Knowledge Generation Function

This paper explores the role of internal and external knowledge in the generation of new technological knowledge. It implements the notion of recombinant knowledge generation function with the appreciation of: (i) the complementary—as opposed to supplementary—role of external knowledge and (ii) the role of the size and composition of the internal stock of knowledge. The empirical section is based upon a panel of companies listed on the main European financial markets for the period 1995–2006. The econometric analysis is based on simultaneous equations. The results confirm that R&D efforts and external knowledge are indispensable inputs into the generation of new technological knowledge.     

Hydromagnetic Natural Convection from a Horizontal Porous Annulus with Heat Generation or Absorption

Journal of Engineering Physics and Thermophysics - This paper deals with a numerical study of free convection in a horizontal cylindrical annulus filled with a fluidsaturated porous medium in the...     

内压缩空分流程中主换热器的设计

介绍内压缩空分流程中主换热器的设计及方法,特别是针对超临界流体在板翅式换热器的设计。并结合板翅式换热器程序软件对多股流介质在设备中的传热及阻力进行分析,优化设计了设备结构。     

Disturbance in Thermo-Microstretch Elastic Medium With Internal Heat Source

The present investigation is aimed at studying the deformation in thermo-microstretch elastic medium occuping the region y ? 0 with a stable internal heat source. A nonviscous fluid layer of height h is overlying the thermoelastic medium and a mechanical source of constant magnitude is applied along the fluid/solid interface. The normal mode analysis is used to obtain the exact expressions for displacement components, force stress, and temperature distribution. The numerical results are given and presented graphically for the Green–Lindsay theory of thermoelasticity. The variations of the considered variables through the horizontal distance are illustrated graphically. Comparisons are made with the results in the presence and absence of microstretch and microrotation parameters.