低合金钢靶板受尖头弹冲击的变形与断裂

研究了低合金钢板在尖头弹冲击条件下的侵彻过程,讨论了应力条件和材料冶金质量对损伤和断裂的影响。结果表明,在侵彻过程前期靶材主要表现为三向压应力下的塑性流动;中期,靶材挤压流动,靶材内部的流速差造成剪切变形,并导致沿轧制偏析带的开裂;后期,靶材在剧烈剪切作用下剪切变形、局部失稳、形成剪切带和沿剪切带的开裂或撕裂。断裂按微孔聚集型机制进行。通常所谓花瓣型开裂实质上就是上述在切应力作用下的剪切撕裂。     

Combining Digital and Traditional Visualisation Techniques in Community-Based Planning and Design

Public participation is a key component in environmental planning and design. Yet too often, architects and planners are not equipped with effective tools and visualisation techniques to generate meaningful public input. Architects and planners are increasingly turning to computer technology; computer imaging can be used to support exploration of alternatives by enabling community members to visualise opportunities and scenarios before committing to a course of action (McClure, 1997). This paper explains how a Geographic Information System (GIS) and an artist played critical roles in a participatory planning process in Chicago's Pilsen neighbourhood. The GIS provided community leaders, planners, architects and designers with an interactive visualisation of the neighbourhood context. It also provided examples of design prototypes in relation to their geographic context. The artist, on the other hand, translated neighbourhood residents' ideas into quick sketches, merging their ideas and thoughts into a shared neighbourhood vision. Both of these elements – the GIS and the human artist – provided a means for residents to visualise past, present, and future neighbourhood conditions, enabling them to have a greater voice in the design of their neighbourhood. Our findings suggest that effective visualisation may be achieved through combining traditional and computerised visualisation tools, and that effective visualisation could assist in bridging the gap between professional designers and non-designers.     

Exploring interactivity: user ability and the Chinese diaspora

Abstract

This paper focuses on two areas of enquiry, the phenomenon of interactivity and how ideas from outside of interaction design can expand our understanding of interactivity. Although generally seen as the user's ability to access information, interactivity's capacity can extend to the shaping of content and meaning. The paper proposes that visualities produced by diasporic individuals reveal the potential of users for reflexivity and intervention. It draws on theories of postcolonial identity and the mixing of cultural meanings of diasporic people to highlight the importance of allowing users to experience autonomy, agency and self-determination in digital media.     

Proposals for creative uses of computer graphics in architectural design

Computer graphics are used by architects mainly for presentation purposes. However, the rapid pace of the development of computer technology enables more creative applications. This research proposes the use of dynamically simulated computer graphics as an evaluation tool for architectural design. Since buildings are living entities, whole life cycles of buildings should be dynamically simulated in highly visualised virtual environments to evaluate the future performance of prospective designs. Two areas that seem especially promising for near future (evaluation of user-building interaction and visualisation of environmental factors) are mentioned and some proposals are presented for the future use of dynamic simulations in virtual environments.     

IGC synthesis of tin nanophase particles Part I: Study on convection gas currents in IGC chamber

Abstract

In order to optimise process variables during the synthesis of tin nanophase particles in an inert gas condensation (IGC) chamber, a two-dimensional finite difference method (FDM) simulation on convection gas currents is proposed and calculated for various boundary conditions. The convection gas velocity and temperature for the 95×105 positions in the chamber were calculated by simulation and compared with experimental results. In the FDM simulation, the governing equations consisted of continuity, momentum, and energy equations. The effects of convection gas pressure, evaporation temperature, position of the evaporation source, and chamber size on the formation of convection currents were investigated by the FDM simulation and experiments. It turned out that among various process variables, the convection gas pressure played the most important role in the formation of the convection gas current that gave rise to an impact on the shape and size of synthesised tin nanophase particles.     

Study on Thermal Deformation Behavior and Properties of Vacuum Hot-press Sintered W(50)/Cu-Al_2O_3 Composite

In this work, the tungsten particulate reinforced Al2O3 dispersion strengthened copper base composites were successfully fabricated by using a vacuum hot-press sintering method. With the test temperature varying from 650 to 950 ℃ and the strain rate varying from 0.01 to 5 s-1, the W(50)/Cu-Al2O3 composites were isothermally compressed on a Gleeble-1500D thermal simulator. The true stress-strain curves of the W(50)/Cu-Al2O3 under different test conditions were obtained. The dynamic recrystallization of the W...     

钛合金焊接件密封问题研究

水下大功率振源体的质量关键除了焊接质量就是密封面的密封性,特别是焊接结构的强振体能否达到良好的密封性是工艺结构的一大难点。根据我们现有的机械加工设备能力和振源体结构特点,无法对振源体组焊件整体真空消应热处理后进行密封面的加工。文中介绍了采用修配座圈窗盖和增大O形圈截面直径的方法,提高了振源体组件的密封性。     

Modeling of Mechanical Characteristics in Hot Deformation of 4130 Steel

In this investigation, hot compression tests were performed at 900 °C ? 1100 °C and strain rate of 0.001 ? 0.1 s^?1 to study hot deformation behavior and flow stress model of 4130 steel. Based on the classical stress–dislocation relations and the kinematics of the dynamic recrystallization, the flow stress constitutive equations of the work hardening‐dynamical recovery period and dynamical recrystallization period were established for 4130 steel, respectively. The validity of the model was demonstrated by comparing the experimental data with the numerical results. The agreement of this comparison is quite reasonable.     

Research on forecasting model of sandstone deformation rate during sine wave loading segment under the lag effect

To reduce data variance caused by individual differences of different samples,a new experimental method is proposed by loading and unloading the axial forces with different frequencies and different waves of a certain load amplitude to the same rock sample without damaging it.Lag time segments are defined and fractionized into segments I and Ⅱ.Criterions for seg-mentation,definitions of relevant parameters and empirical analysis are also offered afterwards.In the course of sinusoidal loading,the serious pea...