从无序到有序，从耗散结构到混沌

研究了非线性科学中耗散结构和混沌的机理和特点，探讨了远离平衡态的非线性开放系统在自组织作用下的演变规律，从而得出了宇宙从无序到有序，从耗散结构到混沌演化的结论。     

从原子到星系

力学是研究各种对象的运动和平衡的科学。它是全部技术、工业、建筑工程的基础科学,特别是建造各种陆、水、空(包括航空和空间技术)运输工具的科学基础。不仅如此,自然科学的主要学科,包括数学、物理学、天文学、化学、生物学,都通过共同的自然规律和研究方法联系起来,都应用着共同的概念体系,而这些概念中许多都带有力学的特性。     

经典力学从牛顿到伯克霍夫

本文简述经典力学从牛顿力学到伯克霍夫力学的发展过程,以及各阶段的内容和意义     

从绊马索到航母的拦阻索

叙述航母舰载飞机被拦阻索协助降落的运动过程, 作简单的力学分析.     

从主轴表示到抽象表示

本文提供一个系统的方法,将主轴法的结果转换为不依赖于主标架的抽象表示,从而把主轴法结果的进一步应用向前推进了一大步。      

从符号动力学到语法复杂性

本文介绍符号动力学和语法复杂性的一概念，并以单峰映为主的对象综述这方面的研究情况，对其中的部分结果作出严格和证明，对于所涉及的问题列出较丰富的文献以供参考。     

从牛顿力学到狭义相对论

本文概要地介绍了爱因斯坦狭义相对论的产生的历史背景及其运动学的内容和结论，特别强调了修改牛顿绝对同时性定义是狭义相对论得以产生的关键．此外，简要介绍了相对论动力学及其成就，这些成就也是对狭义相对论的检验．最后，阐述了狭义相对论的未来发展方向．     

从生物力学到力学生物学的进展

本文介绍了现代生物力学的发展历程和冯元帧先生的贡献、力学生物学的概念与发展以及我国生物力学的发展历程和力学生物学的研究新进展;思考了从生物力学到力学生物学的进展与现状;展望了我国生物力学学科发展的愿景.     

从竹蜻蜓到直升机旋翼系统

通过对蜻蜓目昆虫的古文献记载、蜻蜓的飞行特点以及葛洪在《抱朴子》中有关“飞车” 记载的分析,指出现有文献中关于“竹蜻蜓” 起源说法的不当之处．在分析竹蜻蜓的直升飞行状态和倾斜飞行的进动特性的基础上,阐述了直升机旋翼系统与竹蜻蜓的不同之处．指出直升机旋翼系统的拉力产生原理虽近似于竹蜻蜓,但现今已发展成为一个非常复杂的系统,科技含量远高于竹蜻蜓. 古代的发明是由生活经验促成,与现代许多发明之原理相近,但是没有及时形成知识体系,仅停留在个案层面,不易推而广之;需要把经验逻辑化、体系化,才便于指导工程实践,形成良性循环.     

从生物力学到力学生物学的进展

本文介绍了现代生物力学的发展历程和冯元帧先生的贡献、力学生物学的概念与发展以及我国生物力学的发展历程和力学生物学的研究新进展;思考了从生物力学到力学生物学的进展与现状;展望了我国生物力学学科发展的愿景.     

Mixed convection from upward flow of hot air to a cooled vertical pipe

An experimental study had been carried out to investigate the buoyancy-opposed mixed convection from an upward flow of hot air to a vertical pipe with a cooled surface. The investigation covered a wide range of flow regime, ranging from the “free convection significant” to the “forced convection significant” conditions. Reynolds number of the flow extended from 966 to 14780, whereas the Buoyancy parameter, Ω [=Gr_d/(Re_d)²], varied from 0.008 to 2.77. A steady stream of hot air at a moderate pressure and a Prandtl number of 0.707 was arranged to flow upward through a vertical steel pipe, whose external wall was cooled uniformly by ambient air at 20°C. Test section of the vertical pipe was 1625 mm long with an internal diameter of 156 mm and an external diameter of 166 mm. Air temperature at inlet of the test section was varied from 40°C to 70°C. Both radial temperature and velocity profiles of the airflow were measured at inlet and exit of the test section respectively. Temperatures along the pipe wall were also measured. Non-dimensional expression for the prediction of the average heat transfer coefficient of the mixed convection from an upward flow of hot air to a vertical pipe with a cooled surface was developed from the experimental results. Convection heat transfer was found to impair when the flow is laminar and was enhanced for turbulent flow condition. Received on 20 July 1998     

Drift of large-scale hot thermals in stratified air flows

A difference method developed for the calculation of the three-dimensional unsteady flows of a viscous heat-conducting gas is used to investigate the influence of a horizontal wind, stratified with respect to height, on the motion of the eruption clouds of a volcano. It is shown that as the intensity of the air flow rises and its stratification increases the rate of ascent of the thermal decreases. Data are obtained for the features of the motion of the vortex rings formed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 173–176, November–December, 1984.     

Simulation of glass cutting with an impinging hot air jet

Thermal cutting of glass sheet due to an impinging hot air jet is simulated and analyzed. Induced thermal stresses due to the moving heat source can be used to stably initiate and attract a crack toward the jet axis. Relative motion between the jet and glass sheet then can be used to cut the glass sheet. This paper presents a theoretical study of this process for straight cuts. Process simulation is accomplished by analyzing the coupled temperature and stress fields together with the fracture mechanics criteria for the crack growth.A finite element remeshing technique is employed for the analysis and singular elements are used around the crack tip for a more precise computing of the stress intensity factor. It is shown that a certain minimum air jet temperature for a given nozzle velocity and a certain maximum air jet velocity for a given temperature are required for continuous cutting. The results of the simulation show a good agreement with the published results in the literature. However a variating nature is detected for the distance between the crack tip and the air jet nozzle from a starting value to the steady-state one.     

Limited-view optical tomography technique and its application to temperature field measurement in flow of hot air

In this paper, a limited-view optical tomography technique is presented, which contains an orthographic holography system, an image processing system and the simultaneous algebraic reconstruction technique (SART). Using this technique, the temperature field of a cross section in the flow of hot air from a nozzle is measured. The measured results are satisfactory. The project supported by the National Natural Science Foundation and the State Science and Technology Commission of China     

Gas temperature in the trace of water droplets streamlined by hot air flow

In order to obtain the knowledge necessary for developing new effective fire extinguishing technologies, we determined experimentally the gas temperature in the trace of water droplets streamlined by hot air flow. It was important to establish how much the temperature in the droplet trace decreases and how fast it recovery to the initial temperature field after the droplet evaporation. The following parameters were varied: droplet size from 1.3 mm to 1.7 mm, velocity from 1 m/s to 5 m/s, initial airflow temperature from 473 K to 773 K, number of droplets (one or two), and the arrangement of droplets relative to the hot inflow (serial or parallel). The study proves the theoretical hypothesis about a significant influence of evaporation on the temperature in the water droplet trace. When a temperature trace of water droplets is formed, irrespective of their arrangement, the role of the evaporation process strengthens with the gas flow temperature rising. Furthermore, the study specifies typical longitudinal dimensions of the aerodynamic and temperature traces of water droplets. It has been established that when droplets are located in series and in parallel, their combined impact on the temperature and velocity of the gas flow in the medium differs rather considerably.     

Heat and mass transfer characteristics of air bubbles and hot water by direct contact

 This paper has dealt with direct contact heat and mass transfer characteristics of air bubbles in a hot water layer. The experiments were carried out by bubbling air in the hot water layer under some experimental conditions of air flow rate, inlet air temperature and humidity as a dispersion fluid, and hot water temperature and hot water layer depth as a continuous fluid. Heat transfer and evaporation of water vapor from hot water to air bubbles occurred during air bubbles ascending into the hot water. Air bubble flow patterns were classified into three regions of independent air bubble flow, transition and air bubble combination growth. Non-dimensional correlation equations of direct contact heat and mass transfer between air bubbles and hot water were derived by some non- dimensional parameters for three regions of bubble flow pattern. Received on 14 July 2000 / Published online: 29 November 2001     

Ultra fast cooling of hot steel plate by air atomized spray with salt solution

In the present study, the applicability of air atomized spray with the salt added water has been studied for ultra fast cooling (UFC) of a 6 mm thick AISI-304 hot steel plate. The investigation includes the effect of salt (NaCl and MgSO₄) concentration and spray mass flux on the cooling rate. The initial temperature of the steel plate before the commencement of cooling is kept at 900 °C or above, which is usually observed as the “finish rolling temperature” in the hot strip mill of a steel plant. The heat transfer analysis shows that air atomized spray with the MgSO₄ salt produces 1.5 times higher cooling rate than atomized spray with the pure water, whereas air atomized spray with NaCl produces only 1.2 times higher cooling rate. In transition boiling regime, the salt deposition occurs which causes enhancement in heat transfer rate by conduction. Moreover, surface tension is the governing parameter behind the vapour film instability and this length scale increases with increase in surface tension of coolant. Overall, the achieved cooling rates produced by both types of salt added air atomized spray are found to be in the UFC regime.