An approach to determining the workability diagram based on upsetting tests

To determine a workability diagram for bulk metal forming processes, it is proposed to use experiments in which fracture occurs at a free surface. A good example of such experiments is an upsetting test with profiled dies. An advantage of this method is that fracture conditions are formulated in terms of strain components whereas stresses are excluded using an exact theoretical solution. In the present study three axisymmetric upsetting tests, with flat dies and with conical dies, are carried out to determine the strain to fracture. The method proposed is then combined with these experimental data to find an approximation to the workability diagram of a tool steel.     

3-D NONLINEAR SUPERCAVITATING FLOW IN A GRAVITY FIELD

In this paper,perturbation method and Fourier-cosine-expansion method are used to solve a 3-D nonlinear problem of a supercavitating flow in an inclined field of gravity at large Froude numbers.By expanding the velocity potential into a power series of a small parameter,the original 3-D nonlinear problem is reduced to a number of 2-D ones. The solutions of the first three orders are derived in detail and expressed in terms of the complete elliptic integrals of the first and second kinds.Then the boundary integral equation method is applied to get the numerical solutions for each order.Computational results are provided for supercavitating flows past cones under various flow conditions.     

A conforming quadrilateral plate bending element revisited

A new formulation of a 16-degree-of-freedom conforming quadrilateral plate bending element using the Cartesian co-ordinates is presented. The displacement function w is taken as a slight modification of bicubic polynomial in the Cartesian co-ordinates. Use of this expression in the construction of finite element representations is expected to be useful specially for microcomputers. The simple stiffness matrix subroutine, coded in FORTRAN 77, for the general quadrilateral plate bending element is listed in the Appendix.     

Formation of Malonaldehyde, Formaldehyde, and Acetaldehyde in Apple Juice Induced by Ionizing Radiation

ABSTRACT: We investigated the effects of ionizing radiation on the formation of malonaldehyde (MA), formaldehyde (FA), and acetaldehyde (ACT) in apple juice. The formation of MA, FA, and ACT in both pasteurized and fresh juice increased with radiation dose. The G values (number of species formed per 100 eV absorbed) for MA, FA, and ACT in pasteurized juice were 0.0056, 0.061, and 0.044, respectively. MA concentration decreased rapidly during storage at 5°C, while ACT and FA did not. Irradiation-induced formation of MA, FA, and ACT decreased with decreasing irradiation temperature. Exclusion of oxygen during irradiation reduced formation of ACT and FA, but not MA. Adding 1000 ppm of ascorbate, sorbate, or sulfite to juice before irradiation also decreased MA formation.     

Quasi-steady state natural convection in a tilted porous layer

Quasi-steady state laminar natural convection in an inclined porous layer is studied analytically and numerically. On the basis of the Darcy-Oberbeck-Boussinesq equations, the problem is solved analytically in the limit of a thin porous layer heated on one side by a constant heat flux while the other boundaries are maintained adiabatic. For quasi-steady state, the flow and temperature fields and overall heat transfer rates are obtained in terms of the controlling parameters and the onset of convection in a bottom-heated horizontal system is predicted. It is also demonstrated for the case of a bottom-heated layer that for sufficiently small inclinations, multiple unicellular quasi-steady states exist, some of which are unstable. A numerical study of the same phenomenon, obtained by solving the complete system of governing equations, is conducted. Good agreement is found between the analytical predictions and the numerical simulation.     

无铅无DOP的PVC护套料配方的研究

介绍了不含铅等有害重金属和 DOP,而且符合美国 U L6 2柔软线及装配线要求的电缆料的研究过程 ,阐述了无铅无 DOP配方中 PVC、增塑剂、稳定剂、防火剂、抗氧剂、填充剂、着色剂等原料的选择要求及配方的安全性能     

阻燃电缆和耐火电缆的结构、特性及选用

介绍了阻燃电缆和耐火电缆的概念、特性、结构及分类，并针对不同类别电缆的具体特性结合现场供电要求提出了上述电缆在设计选用、订货及敷设施工中应注意的几个问题。     

无氟液相法制备骨架高硅沸石的研究

运用ＸＲＤ衍射、红外光谱、固体核磁共振、氨吸附差热、微型脉冲反应等手段对无氟液相法制备的高硅Ｙ沸石的结构性质、酸性及裂化活性进行研究，并与液相氟硅酸法制备的高硅Ｙ沸石进行比较。结果表明，用无氟液相法制备的产品重复性较好，具有与氟硅酸法制备的样品相似的补硅效果，并且其热、水热稳定性及裂化活性比氟硅酸法制备的产品更佳。     

复杂变截面梁的轴向自由振动分析的近似方法

介绍了带有附加影响的变截面梁轴向自由振动问题的求解方法－模态摄动法，这一方法在由等截面均匀梁低阶主模态函数组成的模态子空间中，将复杂梁的变系数微分方程的求解化为线性代数方程组的求解，从而简化了计算过程，通过与其它方法的比较，说明了本文方法的优越性。     

Nucleation Processes Close to the Spinodal

Using an analytical equation of state (EOS) which describes a system that can exist in a liquid or vapor phase, a generalized Landau free-energy expansion around any spinodal point is constructed. For this simple model, the critical exponents associated with the spinodal line are obtained, and the model reduces to the usual expansion around the critical point as a particular case. The approach may become an interesting starting point to study phase separation mechanisms, such as nucleation and spinodal decomposition, far from the critical point. The decay of deeply quenched metastable states close to the spinodal through a nucleation process is analyzed and their mean lifetime is obtained. The results are compared with those obtained through the use of the usual Landau free-energy expansion around the critical point.