某金属矿山板裂围岩采场结构布设优化

为研究板裂围岩采场结构的合理布设方式,在对某金属矿山现场节理和采场破坏情况充分调研的基础上,通过对浅埋板裂结构岩体的力学分析,给出板裂围岩赋存条件下采场安全系数的计算式,计算出不同采场规格和板岩倾角条件下采场的安全系数,研究了浅埋板裂围岩采场的合理结构布设。利用数值分析和位移监测的方法,校验研究结果。研究结果表明:在板裂围岩条件下,采场规格一定时,随着板岩倾角从0°增大到90°,采场的稳定性逐渐增强;板岩倾角为0°时,应加强顶板支护;板岩倾角为45°左右时,采场斜顶须加强支护;板岩倾角为90°时,采场最稳定;沿着板岩倾角为90°左右方向的采场结构布设最为合理。研究结果可为类似金属矿山合理地布设浅埋板裂围岩采场结构提供参考。

发热电缆布设方式对桥面融冰化雪的影响分析

文章基于江苏徐州地区温度气候状况,利用ABAQUS建立以发热电缆为电加热介质的桥面温度场数值模型,研究了发热电缆融冰化雪工程中发热电缆布设方式对冬季桥面温度场的影响。结果表明:桥面的温度场分布和桥面升温时间受发热电缆的线功率、布设深度和布设间距影响较大;发热电缆周围温度梯度较大,增加发热电缆的线功率、减小布设深度和布设间距,可以加快桥面升温速度,从而提高融冰化雪效率。通过对融冰化雪效率、效果、经济性和施工便捷性的综合考虑,建议发热电缆布设的线功率采用28 W/m,布设深度为10 cm,布设间距为10 cm。

发热电缆铺设结构对桥面融冰化雪的影响

利用ABAQUS建立以发热电缆为电加热介质的桥面温度场数值模型,基于江苏徐州地区温度气候状况,研究了发热电缆融冰化雪工程中发热电缆线功率、布设深度和布设间距对冬季桥面温度场的影响。结果表明:温度梯度较大位置处于发热电缆周围。桥面的温度场分布和桥面升温时间受发热电缆的线功率、布设深度和布设间距影响较大;加快桥面升温速度可以增加发热电缆的线功率、减小布设深度和布设间距,从而提高融冰化雪效率。通过对融雪化雪效率效果、经济性和施工便捷性的综合考虑,建议发热电缆布设的线功率采用28 w/m,布设深度为10 cm,布设间距为10 cm。

不同天线组合对GPS姿态测量精度的影响分析

GPS姿态确定的精度不仅与单历元基线解算精度有关,还受基线长度和天线布设结构的影响。探讨了GPS姿态测量系统中基线长度和天线布设结构与姿态测量精度的关系。仿真结果表明:增加航向基线长度,能够提高航向角和俯仰角的精度,增加横向基线长度,能提高横滚角的精度;当基线长度一定时,将两基线正交布设,横滚角的精度最高。

Challenges to Data-Path Physical Design Inside SOC

Previously,a single data-path stack was adequate for data-path chips,and the complexity and size of the data-path was comparatively small.As current data-path chips,such as system-on-a-chip (SOC),become more complex,multiple data-path stacks are required to implement the entire data-path.As more data-path stacks are integrated into SOC,data-path is becoming a critical part of the whole giga-scale integrated circuits (GSI) design.The traditional physical design methodology can not satisfy the data-path performance requirements,because it can not accommodate the data-path bit-sliced structure and the strict performance (such as timing,coupling,and crosstalk) constraints.Challenges in the data-path physical design are addressed.The fundamental problems and key technologies in data-path physical design are analysed.The corresponding researches and solutions in this research field are also discussed.

Structural design and experimental research of microwave radiation heater for asphalt pavements

In order to improve the efficiency of heating and the uniformity of temperature distribution in recycling asphalt mixtures, a pyramidal radiation heater is designed. The principles of designing horn surface size and antenna length are established according to the law of energy conservation and microwave antenna radiation theory. Modeling and simulation are carried out using IE3D software. The simulation results demonstrate that, with a fixed horn surface size, the shortened electric antenna length is the main factor leading to the improved heating uniformity. On the other hand, with a fixed antenna length and diminished surface size, the standing wave ratio decreases with the improved radiation efficiency. Furthermore, the efficiency of radiation drops with increased distance between the horn surface and the asphalt pavement. Microwave heating experiments are carried out using this type of heater. The temperature distribution of asphalt samples is obtained by the grid temperature measurement method, and Matlab simulation is performed. The experimental results are in good agreement with the simulation.

Crest-Height Distribution of Nonlinear Random Waves

The wave crest is an important factor for the design of both fixed and floating marine structures.Wave crest height is a dominant parameter in assessing the likelihood of wave-in-deck impact and resultant severe damage.Many empirical and theoretical distribution functions for wave crest heights have been proposed,but there is a lack of agreement between them.It is of significance to develop a better new nonlinear wave crest height distribution model.The progress in the research of wave crest heights is reviewed in this paper.Based on Stokes' wave theory,an approximate nonlinear wave crest-height distribution formula with simple parameters is derived.Two sets of measured data are presented and compared with various theoretical distributions of wave crests obtained from nonlinear wave models and analysis of the comparison is given in detail.The new crest-height distribution model agrees well with observations.Also,the new theoretical distribution is more accurate than the other methods cited in this paper and has a greater range of applications.

A distributed software architecture design framework based on attributed grammar

Software architectures shift the focus of developers from lines-of-code to coarser-grained architectural elements and their overall interconnection structure. There are, however, many features of the distributed software that make the developing methods of distributed software quite different from the traditional ways. Furthermore, the traditional centralized ways with fixed interfaces cannot adapt to the flexible requirements of distributed software. In this paper, the attributed grammar (AG) is extended to refine the characters of distributed software, and a distributed software architecture description language (DSADL) based on attributed grammar is introduced, and then a model of integrated environment for software architecture design is proposed. It can be demonstrated by the practice that DSADL can help the programmers to analyze and design distributed software effectively, so the efficiency of the development can be improved greatly.

关于汽车车身结构的布设与安全性分析

随着我国汽车保有量的快速增长,以及公路交通建设尤其是高速公路建设的快速发展,车辆的运行速度不断加快且事故发生率也在不断提高,这些都对车身结构及其安全性提出了许多新的要求。本文对车身结构布设给汽车的性能及安全性造成的影响进行了分析,并在此基础上对车身结构布设的安全性优化措施进行了探讨。

Effect of Vibro-lnsulation on Restriction of Vibration Transfer from Subsoil into the Building

The solution of vibration transfer from the subsoil to the structure is demonstrated using the example of a multi-storey reinforced concrete building, founded on a dual foundation plate. An anti-vibration layer of rubber has been designed between the two plates. Two 3D numerical models of the building take into account the individual storeys, firstly together with the lay-out of the rubber distribution in the foundation pan and secondly without this rubber part. For response analysis, the measured time histories in the construction area were selected and then the typical response was used as an input for a dynamic analysis of the structure.

Distribution of electric field and design of devices in GaN avalanche photodiodes

We have investigated the distribution of the electric field in p-i-n GaN avalanche photodiodes under different reverse bias values. type and separate absorption and multiplication （SAM） type We have also analyzed the influences of the parameters of each layer, including width and concentration, on the distribution of the electric field, especially on the breakdown voltage. It is found that a relatively high concentration of p-GaN （higher than 1×10^18 cm-3） and low cartier concentration of i-GaN （lower than 5×1016 cm-3） are helpful to restrict the electric field and reduce the breakdown voltage. In a SAM （p-i-n-i-n） structure, a suitable choice should be made for the concentration and thickness of the intermediate n-GaN layer in order to decrease breakdown voltage and prevent the device from degenerating into a p-i-n structure. Finally, the optimized material parameters of each layer are proposed.

Research on failure scenarios of domes based on form vulnerability

In this paper, form vulnerability theory was applied to the analysis of the failure mechanisms of single-layer latticed spherical shells subjected to seismic excitations. Three 1/10 scale testing models were designed with characteristics as follows： Model 1 possesses overall uniform stiffness and is expected to collapse in the strength failure mode as some members become plastic; Model 2 possesses six man-made weak parts located on six radial main rib zones and is expected to collapse in the dynamic in- stability mode with all members still in the elastic stage; Model 3 strengthens the six weak zones of Model 2, and therefore, its stiffness is uniform. Model 3 is proposed to collapse in the strength failure mode when the members are still in the elastic stage By increasing the peak ground accelerations of seismic waves gradually, the shaking table tests were carried out until all three models collapsed （or locally collapsed）. On the basis of form vulnerability theory, topological hierarchy models of the test models were established through a clustering process, and various failure scenarios, including overall collapse scenarios and partial collapse scenarios, were identified by unzipping corresponding hierarchical models. By comparison of the failure scenarios based on theoretical analysis and experiments, it was found that vulnerability theory could effectively reflect the weak- ness zones in topological relations of the structures from the perspective of internal causes. The intemal mechanisms of the distinct failure characteristics of reticulated shells subjected to seismic excitations were also revealed in this process. The well-formedness of structural clusters, Q, is closely related to the collapse modes, i.e., uniform changes of Q indicate a uniform distribution of overall structural stiffness, which indicates that strength failure is likely to happen; conversely, non-uniform changes of Q indicate that weak zones exist in the structure, and dynamic instability is likely to occur.

Structural bionic design for high-speed machine tool working table based on distribution rules of leaf veins

High-speed machine tool working table restrains the machining accuracy and machining efficiency,so lightweight design of the table is an important issue.In nature,leaf has developed a plate structure that maximizes the surface-to-volume ratio.It can be seen as a plate structure stiffened by veins.Compared with a high-speed machine tool working table,leaf veins play a role of supporting part which is similar to that of stiffening ribs,and they can provide some new design ideas for lightweight design of the table.In this paper,distribution rules of leaf veins were investigated,and a structural bionic design for the table was achieved based on regulation of leaf veins.First,statistical analysis on geometric structure of leaf veins was carried out,and four distribution rules were obtained.Then,relevant mechanical models were developed and analyzed in finite element software.Based on the results from mechanical analysis on those relevant models,the four distribution rules were translated into the design rules and a structural bionic design for the working table was achieved.Both simulation and experimental verifications were carried out,and results showed that the average displacement of the working table was reduced by about 33.9%.