Implementation of road horizontal alignment as a whole for CAD

Road horizontal alignment contains three elements: straight line,circular arc,and clothoid.In AutoCAD,clothoid can only be fitted by polyline or spline,and the graphics which are separated from the road data are independent of each other.Therefore,it is necessary to develop a new curve for road horizontal alignment.Firstly,the differential approximation and series integration methods for clothoid were discussed.Secondly,the geometric formulae for road line which contain the three elements were derived as a whole.Then,the advantages and feasibility of customizing a road line class,which was derived from the curve base class,were analyzed based on ObjectARX(AutoCAD Runtime eXtension) techniques.Finally,the data structure and operations for the road line class were stressed.The experimental results show that the road line can integrate the road elements,graphics and data to implement the graphics-oriented design,which can be widely used in road alignment design.

Tracking of horizontal alignment of the long and large diameter uncharged hole in NATM tunnel

The long and large diameter uncharged hole boring(LLB)method is a cut blasting method that minimizes blast-induced vibrations by creating long and large diameter uncharged holes at the excavation face of tunnels prior to tunnel excavation.Drilling in this method typically uses a 50 m long with a 382 mm diameter hammer bit in the horizontal direction at the tunnel face.However,the significant weight and uni-directional rotation of the rod head,as well as variables such as geological characteristics,machine conditions,and inexperienced operators result in significant deviation from the target borehole alignment that hinders the vibration-dampening effect of the uncharged holes.Furthermore,since there is no method to verify the alignment of the boreholes until main tunnel construction,borehole misalignment is often not discovered until weeks after construction,which requires tunnel construction to cease until the equipment can be remobilized and an additional borehole be created,causing significant delays and increased costs for the entire tunnel project.In this study,the borehole alignment tracking and ground exploration system(BGS)is developed to predict and monitor the quality and alignment of boreholes for cut blasting methods such as the LLB methods immediately after boring.The BGS was subsequently tested at a subway construction site to evaluate its performance in the field.The measurements yielded by the BGS were compared with manually measured boring positions at every 5 m along the borehole.Although the BGS showed a maximum deviation of approximately 12%at a local point where the hole surface was relatively rough,the accuracy for the final boring position was approximately 97%,demonstrating excellent precision of the alignment tracking system.The BGS demonstrates excellent performance in predicting ground conditions and the boring quality of a cut hole immediately after drilling,and shows promise in various other applications for monitoring borehole alignment.

Preparation of horizontally aligned single-walled carbon nanotubes with floating catalyst

A strategy to prepare horizontally aligned single-walled carbon nanotubes(SWNTs) at moderate temperatures(≤600 ℃) were developed.Using ferocene as the catalyst precursor,Fe nanoparticles are formed in the gaseous phase and catalyze the nucleation and growth of SWNTs in situ.Then the resultant SWNTs are deposited onto the substrates downstream and aligned by the surface lattice of the ST-cut single crystal quartz.The preparation of SWNT arrays at moderate temperatures is important for combining the tube growth with device fabrication.

Pave the way to the batch production of SWNT arrays for carbonbased electronic devices

Single-walled carbon nanotubes(SWNTs)have been regarded as one of the most promising candidates to supplement or even replace silicon in the post-Moore era.The requirement is to prepare the horizontally aligned SWNTs arrays(HASAs)with multiple indicators,including high density,high semiconducting purity,and wafer-scale uniformity.However,after all the fevered works being done in controlled synthesis,we still have a long way to go before realizing the application of SWNTs in highly performed electronic devices.The methods of batch production and high-throughput characterization techniques of the HASAs are the two main challenges.In this outlook,we first summarized the progresses in synthesis of HASAs with either high density or high semiconducting purity.Then the methods adopted in characterizing SWNTs and HASAs were discussed according to the different principles of characterization techniques.Afterwards,the development of carbon nanotube based electronic devices,specifically,the field effect transistors(FETs),was reviewed from three perspectives.The problems involved in electronic applications bring forward the higher request to the HASAs itself.Therefore,in the end of this outlook,we prospected the future of the synthesis and corresponding characterization of HASAs,and tried to provide our ideas about how to pave the way to the batch production of HASAs for carbon based electronic devices.