输气管道内壁涂漆的经济性

在输气管道内壁涂漆,半个多世纪以来进行了许多的实践和测量,其显著的经济效益已经为人们所认识.简要介绍了输气管道内壁的涂装工艺、质控标准及其测试结果,着重总结了它的优越性和经济性.     

Critical Factors in the Templated Grain Growth of Textured Reaction-Bonded Alumina

The Templated Grain Growth (TGG) of Al₂O₃ occurs in three stages: densification, radial growth of individual template grains until template impingement, and template grain thickening. Significant template growth occurs only after densification to ∼90% density. Template loading determines the inter-template spacing and, subsequently, the degree of growth. The spacing distance can be predicted from the initial template concentration and template dimensions. Thermodynamic conditions favorable for template growth occur when the size ratio between the template thickness and matrix grains is ≥1.5. The initial template concentration should be less than a critical template concentration, V _T,C, to achieve textured ceramics with a narrow orientation distribution. For this system, which uses 20 ± 5 μm × 2 μm template particles and uniaxial pressing as a forming technique, V _T,C is between 5 and 10 vol%.     

Heat exchange during a slow flow of a liquid between coaxial conical surfaces

The problem of convective heat transfer during a slow liquid flow in conical annular channels is considered. For third-kind thermal boundary conditions, the problem is solved by separation of variables. The temperature distribution is represented as the product of an infinite Whittaker-function series in lateral coordinate and an exponential of longitudinal coordinate. Heat transfer in a variable-width annular conical channel is analyzed by stepwise approximation. Optimization of the distributing sections of extruder dies is shown to be possible.     

Laboratory and Field Study of the Attraction of Male Pea Midges, Contarinia pisi, to Synthetic Sex Pheromone Components

Behavioral activity of the recently identified sex pheromone components of the pea midge, Contarinia pisi, (2S,11S)-diacetoxytridecane, (2S,12S)-diacetoxytridecane, and 2-acetoxytridecane, was tested in wind tunnel and field-trapping experiments. In the wind tunnel, the attractancy of the three-component blend in a 7 : 10 : 0.1 ratio (following the above order, mimicking the ratios found in gland extract) did not differ significantly from female gland extract, whereas a mixture of the two major components (7 : 10) only attracted 2% of the males to the source. In the field, traps baited with the three-component blend caught by far the largest number of males. Traps baited with the two major components only caught slightly more than the blank traps, and catches in traps baited with 2-acetoxytridecane alone did not differ from catches in the blank traps. Traps baited with the racemate of all three components did not catch more than the blank traps, indicating that some of the enantiomers are inhibitory.     

Damage monitoring of cement paste by electrical resistance measurement

Electrical resistance measurement is effective for monitoring damage (due to damage infliction and subsequent microcrack opening) and healing (due to microcrack closing) of cement pastes (plain, with silica-fume, and with latex) in real time during repeated compressive loading. Damage causes the resistance to increase; healing causes the resistance to decrease.     

Regularities of heat release in tungsten siliconizing in a gasless combustion wave

An electrothermographic method was used to study the regularities of heat release and formation of the microstructure of tungsten disilicide with wide variation in the temperature regime of sample heating, including conditions modeling combustion-wave propagation in mixtures of tungsten and silicon powders. Emphasis is on the heat-release stage due to the crystallization of the disilicide phase from a supersaturated melt of WSi₂-Si. At this stage of the process, self-acceleration of the heat release is observed even when the sample temperature decreases. Growth of tungsten disilicide crystals occurs only at the heat-release stage. When the system is kept at the maximum temperature of the thermogram, further crystal growth is not observed over a period of time exceeding the duration of heat release by a factor of 10–20. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 3, pp. 65–71, May–June, 2000.     

Study on the friction interface evolution during rotary friction welding of tube

In this study, evolution characteristics of the friction interface during rotary friction welding of tube were investigated. The friction interface that obtained at different welding stage were observed by confocal laser scanning microscopy. The results show that the friction interface transforms from sliding friction state to visco-plastic deformation state when the welding torque reaches the peak value. In addition, based on the thermodynamic framework extracted from the maximum entropy production principle, an analytical model for transition criterion from sliding friction to visco-plastic deformation was established. The model was verified by the corresponding experimental results of eight alloys, which indicated that the accuracy and generality of the model is satisfactory.     

Absorption of Nitrous Oxide from Air by Aqueous and Organic Solutions

Theoretical Foundations of Chemical Engineering - Findings from a study of the N2O absorption from an air flow in various aqueous and organic solutions at 293–298 K were reported. The maximum...     

DIFFUSION OF MOISTURE IN DRYING OF SUGAR CANE FIBERS AND BUNDLES

Sugar cane fibers and arrangements of fibers in cylindrical bundles were dried in a thermoanalyzer and their diffusive coefficients were calculated using the slope method. The effect of temperature, moisture content as well as structural changes were analyzed. Diffusion coefficients changed nanlineariy with moisture content and followed an Arrhenius-like functionality with temperature. The analysis of these effects suggested a liquid diffusion transport mechanism of moisture transfer inside sugar cane fibers and bundles.