DELPHI中动态链接库调用之剖析

本文系统介绍了动态链接库（DYNAMIC LINK LIBRARY，简称DLL）的基本概念和对DLL的实现原理进行剖析，使我们对DLL文件的内部结构有一个全面的认识．并通过实例描述如何在DELPHI通过编程实现动态链接库调用过程。     

Demonstration and Analysis of Quadrupedal Passive Dynamic Walking

Animals, including human beings, can travel in a variety of environments adaptively. Legged locomotion makes this possible. However, legged locomotion is temporarily unstable and finding out the principle of walking is an important matter for optimum locomotion strategy or engineering applications. As one of the challenges, passive dynamic walking has been studied on this. Passive dynamic walking is a walking phenomenon in which a biped walking robot with no actuator walks down a gentle slope. The gait is very smooth (like a human) and much research has been conducted on this. Passive dynamic walking is mainly about bipedalism. Considering that there are more quadruped animals than bipeds and a four-legged robot is easier to control than a two-legged robot, quadrupedal passive dynamic walking must exist. Based on the above, we studied saggital plane quadrupedal passive dynamic walking simulation. However, it was not enough to attribute the result to the existence of quadrupedal passive dynamic walking. In this research, quadrupedal passive dynamic walking is experimentally demonstrated by the four-legged walking robot 'Quartet 4'. Furthermore, changing the type of body joint, slope angle, leg length and variety of gaits (characteristics in four-legged animals) was observed passively. Experimental data could not have enough walking time and could not change parameters continuously. Then, each gait was analyzed quantitatively by the experiment and three-dimensional simulation.     

Dynamic pressure in mould flux channel during mould non-sinusoidal oscillation

Abstract

Based on the lubrication theory of mould flux, a mathematical model of dynamic pressure in mould flux channel was developed, and the distribution of dynamic pressure and its variation during non-sinusoidal oscillation were investigated. The effects of casting speed and non-sinusoidal oscillation parameters, including the degree of non-sinusoidal operation (non-sinusoidal factor), amplitude and frequency of oscillation on the dynamic pressure in the mould flux channel, were studied. The results indicate that the maximum negative pressure is decreased, and the maximum positive pressure is increased with increasing non-sinusoidal factor. The optimum value of non-sinusoidal factor is ～0·2. With increasing amplitude and frequency of oscillation, both the negative and positive pressure are increased; moreover, the increment of positive pressure is obviously greater than that of negative pressure; especially when the oscillation frequency is increased, the increment of negative pressure is very little. When the casting speed is enhanced, the negative pressure is increased, but the positive pressure is decreased. Therefore, if the casting speed is increased, the oscillation amplitude needs to be increased, as well as the oscillation frequency needs to be decreased properly. With these adjustments, the positive pressure in mould flux channel is nearly unchanged. The actions of strand demoulding and cracks welding are kept effective. Moreover, the negative pressure in mould flux channel is increased properly, which causes the flux consumption to increase, so the mould lubrication is improved. Finally, the strand surface quality is improved greatly, and breakout can be avoided. The applicability of the optimised non-sinusoidal oscillation parameters for the two kinds of casting speed has been proven by industrial practice.     

Contact angle and IGC measurements for probing surface-chemical changes in the recycling of wood pulp fibers

The objective of this study was to use dynamic contact angle (DCA) analysis and inverse gas chromatography (IGC) to probe the surface-chemical changes in wood pulp fibers during recycling. A simplified wet-dry-rewet cycle was performed on hardwood bleached kraft fibers to represent the recycling process. The DCA measurements revealed that the overall effect of recycling was an increase in the non-polar (dispersive) component and a corresponding decrease in the polar component of the surface free energy, hence resulting in a total surface free energy that remained essentially unaltered. The DCA experiment also showed that virgin fibers lost both their electronaccepting (γ_S ⁺) and their electron-donating (γ_S ^-) characteristics when converted to paper. Upon rehydration, the fibers recovered some surface acidity (γ_S ⁺) but surface basicity (γ_S ^-) continued to decrease. The changes in polar surface free energy correlate well with the changes in hydroxyl number determined independently using the acetylation method. IGC could not detect changes in the dispersive component of the surface free energy induced by recycling. The acid-base (KA and KB) changes in the IGC measurements were also indistinguishable between virgin fibers and recycled fibers. This research concludes that DCA analysis is preferable to IGC in better reflecting the surface changes in fiber recycling, and γS-can at least be treated as an empirical parameter to complement the hydroxyl availability data in distinguishing among virgin, paper, and recycled fibers.     

Characteristic optimisation of dynamic process parameters in rapid solidified treatment

Abstract

The paper presents a Taguchi dynamic experiment applied in developing a robust, high efficiency electron beam surface hardening process (EBSH). In the present study, a two step parametric design is proposed with methodology using a non-linear system function. In the first step, the system function of the EBSH process is transformed into a linear function and then this model is applied to develop a robust heated treatment process that reduces the variability in maximising the S/N ratio for maximum robustness. In the second step, the ideal function is obtained by adjusting the sensitivity or the slope β of the linear function determined in the first step. The purpose is to adjust the product dimension EBSH machine using the optimised process parameters obtained in the two step design to achieve the desired dimension for the subsequent fine wear resistant surface processing. The results from the experiment show that using the Taguchi dynamic experimental non-linear system with the proposed two step design strategy is a simple, effective and efficient way to develop a robust, high efficiency EBSH process.     

Contact angle measurements and interpretation: wetting behavior and solid surface tensions for poly(alkyl methacrylate) polymers

Low-rate dynamic contact angles of a large number of liquids were measured on a poly(ethyl methacrylate) (PEMA) polymer using an automated axisymmetric drop shape analysis profile (ADSA-P). The results suggested that not all experimental contact angles can be used for the interpretation in terms of solid surface tensions: eight liquids yielded non-constant contact angles and/or dissolved the polymer on contact. From the experimental contact angles of the remaining four liquids, we found that the liquid-vapor surface tension times the cosine of the contact angle changes smoothly with the liquid-vapor surface tension, i.e. γlv cos ζ depends only on γlv for a given solid surface (or solid surface tension). This contact angle pattern is again in harmony with those from other methacrylate polymer surfaces of different compositions and side-chains. The solid-vapor surface tension of PEMA calculated from the equation-of-state approach for solid-liquid interfacial tensions was found to be 33.6 ± 0.5 mJ/m2 from the experimental contact angles of the four liquids. The experimental results also suggested that surface tension component approaches do not reflect physical reality. In particular, experimental contact angles of polar and nonpolar liquids on polar methacrylate polymers were employed to determine solid surface tension and solid surface tension components. Contrary to the results obtained from the equation-of-state approach, we obtained inconsistent values from the Lifshitz-van der Waals/acid-base (van Oss and Good) approach using the same sets of experimental contact angles.     

Simple model for consolidation of metal matrix coated SiC fibre composites

Abstract

A simple approach to modelling the consolidation of matrix coated fibre composites is presented. It employs an existing porous material constitutive model for monolithic materials. It is argued that in the consolidation of metal coated SiC fibres, the deformation primarily occurs in an outer layer of the fibre coating, and the internal core remains undeformed, largely because of the generally hydrostatic compressive loading, and because of the incompressible nature of the material in creep. The consolidation process is therefore not vastly different to that occurs for monolithic metal fibres, and similar equations can therefore be used for the composite consolidation. The constitutive equations have been implemented into general purpose non-linear finite element software within a large deformation formulation by means of two different user subroutines, one providing a general implementation, and the other a cpu time efficient approach. The manufacture and testing of SiC continuous fibre, Ti-6Al-4V metal matrix composite specimens is described and the results of the tests compared with the model calculations, showing that good agreement can be achieved with a simple model. The dependence of volume fraction of fibres and temperature can be introduced empirically through the specification of just two material constants. The model is therefore useful in the development of consolidation processes.     

Effect of dynamic strain aging on fatigue crack growth behaviour of reactor pressure vessel steels

Abstract

Fatigue tests under constant amplitude load were conducted on compact tension specimens of SA533B3 steels with four levels of sulphur content at different temperatures. A modified capacitance type crack opening displacement (COD) gauge was shown to be suitable for fatigue crack length measurement at high temperatures. Test results obtained with different measurement techniques show good consistency. The observation that the Young's moduli measured at a strain rate of 4 × 10^?3 s^?1 for the SA533B3 steels at 150 and 300°C do not decrease with increasing temperature seems to be related to the presence of dynamic strain aging. The fatigue crack growth rates at 150 and 300°C are about two and half times slower than those tested at 400°C because dynamic strain aging prevails at 150 and 300°C. Fractographic examination results suggest that inclusions embedded in secondary cracks enhanced the fatigue crack initiation rather than the fatigue crack growth.     

Corrosion resistance of AA2219 aluminium alloy: electrochemical polarisation and impedance study

Abstract

The addition of copper increases the strength of aluminium, but decreases the localised corrosion resistance of the metal to seawater as the copper containing intermetallics exhibit different electrochemical properties from the matrix. The main requirement of corrosion resistance could be met through the surface modification by removing the copper rich phase. The present work involves investigations of the influence of prior copper removal treatment on the pitting and general corrosion resistance of AA2219 alloy containing a high copper content in different initial thermal tempers. Significant improvement in the pitting and general corrosion resistance after surface copper removal treatment was evident from the results of electrochemical polarisation and the impedance tests. Attempts were also was made to modify the surface further, with a conversion layer of cerium as an alternative to the chromate coating.