A hybrid tubular standing support for underground mines:Compressive behaviour

This paper presents the development of an innovative standing support for underground mines.The main feature of this standing support is its exterior container,a combination of polyvinyl chloride(PVC)with large rupture strain and fibre-reinforced polymer(FRP)with high strength-to-weight ratio.To demonstrate the advantages of this cementitious grout filled PVC-FRP tubular(PFT)standing support,a series of compression tests were conducted.Test variables included the strength of cementitious grout infill material and the thickness of FRP jacket.Compression tests were also conducted on cementitious grout-filled PVC tubular(PT)support and cementitious grout-filled FRP tubular(FT)support.These tests showed that PFT support presents a typical strain-hardening behaviour together with an outstanding axial deformation ability(>20%of the overall height of the support).In addition,the maximum compressive strength of PFT support is much higher than that of the corresponding PT support and FT support.Furthermore,using thicker FRP jacket or high strength cementitious grout material can enhance the load carrying capacity of PFT support.These comparative results indicated that the high performance of PFT support is mainly attributed to the combination of confining constituents(i.e.PVC and FRP)and infill material.

Evaluation of the Performance of the GSSM Under Vibration Based on Normalized Point Source Sensitivity

Giant Steerable Science Mirror( GSSM) is the tertiary mirror of the Thirty Meter Telescope( TMT).To evaluate the performance of the GSSM under the mechanical vibration,the Normalized Point Source Sensitivity( PSSn) is used to understand and characterize the optical performance degradation. First and foremost,the definition of the PSSn is shown and the calculation procedure of the PSSn at the work condition where the telescope aberration is much smaller than seeing is presented to reveal the relationship between PSSn and seeing.Then,the optical degradation due to vibration is achieved by the two methods: one is the statistics moment for the arbitrary froms of vibration and other one is spectrum method for wind load. After the theoretical presence,the simulation is processed. The multi-axis-accelerometers are used to achieve the motion of the mirror. After integrated to displacement signal,the measured signal is applied to the mathematical model of the GSSM and the optical performance degradation under certain mechanical vibration can be achieved. The PSSN flows from 0.996 to 0.994 under some dynamic vibration. And then,the wind load is applied to the mathematical model using spectrum method with the PSSN flows from 0.996 to 0.991. This paper can help the system engineers to predict the performance of the GSSM in various work condition. What is more,PSSn is able to be combined just by simple multiplication,so the optical performance degradation can be easily co-considered with other error sources.

TMT Tertiary Mirror Optical Jitter Model Metrology

To measure the jitter performance of the Tirthy Meter Telescope tertary mirror( TMT M3),the model of jitter based on the accerleration signal is established. First and foremost,the procedure TMT required to processs the jitter data is presented. Then,the jitter of the system is divided into two parts: powered jitter and unpowered jitter. The metric of the jitter is required to be in the form of displacement or angle. So the frequency integration is involved to minify the error source introduced by the tending iterm in the time domain integration.In the evaluation of the power jitter,the accelerometers are used to obtain the rigid body motion of the tertiary mirror. The random decrement technique and dominated mode theory are applied to obtain the model of unpowered jitter. A classical telescope performances a 1. 6"RMS jitter metric; for a four meter scale system,the resonance frequency is around 107 Hz,powering,with 0. 14% damping. Consequently,the tip( 183 Hz,0.6%) and tilt( 193 Hz,0.19%) are both be measured. Using this model,the system engineers can estimate the unpowered jitter when the system is presented in the distortion.

Analysis on Self-compatibility of Artificially Synthesized Brassica napus Lines from Different Cross Combinations

Brassica rapa cuhivars Qinghaidahuang and Menyuan small rape were used as female parents and separately interspecifically hybridized with Zhongchijie- lan to artificially synthesize a number of Brasica napus resources. Observation of meiosis, pollen fertility and pollen tube germination and analysis of self-compati- bility index of these artificial B. napus varieties were conducted. Results showed that pollen mother cells of artificial B. napus lines from two cross combinations all had normal chromosome behavior and high pollen fertility, but the selfing seed-setting and self-compatibility index varied extremely significantly; B. napus lines from cross combination Qinghaidahuang x Zhongchijidan are highly self-compatible, while B. napus lines from cross combination Menyuan small rape x Zhongchijielan are highly self-incompatible. This study analyzed the heredity laws of self-incompatibility trait in artificially synthesized lines and discussed applica- tion prospects of artificially synthesized self-incompatible B. napus lines in rapeseed production.