Numerical Simulation of Multi-track and Multi-layer Temperature Field on Laser Direct Metal Shaping

To improve the mechanical properties of the parts fabricated by Laser Direct Metal Shaping(LDMS),it is of great significance to understand the distribution regularities of transient temperature field during LDMS process.Based on the“el- ement birth and death”technique of finite element method,a three-dimensional multi-track and multi-layer model for the transient temperature field analysis of LDMS is developed by ANSYS Parametric Design Language(APDL)for the first time.In the fab- ricated modal,X-direction parallel reciprocating scanning paths is introduced.Using the same process parameters,the simulation results show good agreement with the microstructure features of samples which fabricated by LDMS.     

Quantitative Relationship Between Multi-Angle Polarized Reflectance and BRDF of Rock

1 IntroductionWhile the multi-spectral, multi-temporal andhyper-spectral remote sensing data are applied toenhance the ability to recognize the targets onground, more and more investigators have realizedthe influence and contribution of the angle informa-tion, namely the 3D spectrum characteristics of thetargets in 2π space, for recognizing and classifyingimages in remote sensing. The traditional unidirec-tional remote sensing can only obtain one directionprojection of targets; therefore it l…     

Studies on the microstructure,optical and electrical properties of organic microcavity devices based on a porous silicon reflector

Due to its low-cost and mature technology, Si has consistently been the mostwidely used semiconductor in microelectronic industry. Nevertheless, as the photolitho-graphic line for integrated circuit devices becomes narrower and narrower, the quantumsize effect appearing in the devices will further limit the development of electronic in-dustry. Si-based optoelectronic integration can increase the operational velocity of inte-grated circuits because photon can propagate three orders faster than …     

Some key technics of drop tower experiment device of National Microgravity Laboratory (China) (NMLC)

Microgravity science and application pro-ject is a very important part of Chinese space effort. This area has been very active along with the international space activities in re-cent years and has got many important re-sults. The completion and running of the international space station will further pro-mote the research activities in the area of microgravity science and application. The National Microgravity Laboratory (China) (NMLC) was established in the mid-dle of the 1990s. Drop towe…     

Design and testing of micro fluidic chemical analysis chip integrated with micro valveless pump

Micro fluidic analysis technology has been developed rapidly since the 1990s. The essentials of the technology are fabricating the micron structure (usually net channels, 20―100 μm wide and 10―30 μm deep) in chips by micro processing, and analyzing the fluids of samples or reagents chemically when they are controlled to flow and to be mixed in the micro structures. The occurrence of the technology makes the miniaturiza-tion, integration and portability of chemical detecting devices possibl…     

Experimental investigation and numerical simulation on the effect of fissure water pressure in vertical sliding surface

1 Introduction Rock slopes usually contain many structural surfaces in geological engineering. However, the mechanism of rock slope failure has not been profoundly understood. Therefore, it is important to deeply analyze the failure mechanism and stability of such rock slopes through experimental investigation and numerical simulation. Previous site investigations show that water is one of the key factors to induce landslide[1―5]. “No landslide without water” vividly points out the importa…     

Experimental and discrete element numerical analysis of side slope instability induced by fissure water underlying impervious bed

1 Introduction The in situ observations and analysis on the landslide events indicate that water is one of the key factors which induce landslide of the mountain mass[1―8]. The mechanism offissure water inducing landslide can be generalized into three aspects: (1) the softening influence of water weakens the strength of materials on the slip surface[9―11]; (2) the cleft water pressure towards the slide slope free face increases sliding force[12―15]; (3) water pressure on the slip surface lo…     

Stochastic structural model of rock and soil aggregates by continuum-based discrete element method

Ancient slope[1], debris-flow deposit[2] and rock-filling dam[3] are usually made of rock and soil aggregates (RSA). The RSA is a typical inhomogeneous and discontinuous medium, and its main characteristics include: (i) loose piling up by blocks or particles, (ii) mixing of different blocks with a range of shapes and sizes, (iii) stochastic distribu- tion of blocks in space, (4) fillings often in between blocks. The mechanical properties of these rock and soil aggregates are commonly obtaine…     

Flume Experiment on Stream Blockage by the Debris Flow From Tributary

Stream blockage by the debris flow from tributary valleys is a common phenomenon in mountainous area,which takes place when large quantities of sediment transported by debris flow reaches a river channel causing its complete or partial blockage.The dam formed by debris flow may causes upstream and downstream flooding,and presents great threat to people and property.Because of the catastrophic influence on people and property,debris-flow dam has attracted many attentions from the researchers and local administration.But,lit- tle attention has been given to the quantitative interrelationships of the potential influential factors.In this pa- per,the interrelationships of important influential factors caused the stream blockage by debris flow were ana- lyzed through flume experiment,and a model to predict the blockage was presented.     

An Investigation of Stochastic Nature of Bed Load Motion in Chuanjiang River

Bed Load Motion and its transport rate is one of the basic issues in river dynamics.In this paper, the authors discussed the stochastic nature of bed load motion in Chuanjiang River in details.Chungjiang lies in the upstream reach of Yangtze River.Its stochastic nature is shown in the following four aspects.Firstly, even though all the conditions are the same,due to the fluctuation of the flow,the bed load discharge and the location and width of sediment transport belts are different.Secondly,during the process of bed load motion, pebbles show the strong nature of intermittence.Thirdly,the sediment discharges through upstream and down- stream reach are not equal,i.e.the pebble motion exists the discontinuity.Fourthly,annual mean transport rates of bed load for different stations are different and variation of transport rate of pebbles for a given station with year is large.The four aspects will be discussed one by one detailedly.