Effect of bolt rib spacing on load transfer mechanism

Rock bolting has firmly used as the coal mine roof reinforcement in underground coal mine. The bolting effect of fully grouted rebar bolt is closely related to the bolt surface profile. This paper provides an experimental study to confirm that bolt rib internal length has great influence on bolting effect. Pull-out tests were conducted using rebar bolt with different rib spacings of 12, 24, 36 and 48 mm representatively from steel tube and from concrete. Results show that peak load increases 25.3% for bolt with large rib spacing. For pull out using concrete block, the increment of peak load between large and small rib spacing is not significant, but the bolt with large rib spacing has great absorption of deformational energy than small rib spacing bolt. This study provides experimental evidence towards optimum design of rock bolt for understand coal mining industry.

A Development of Rom-Exercise Machine Using Linkages(Design of Leg Mechanism by Walking Simulation)

In this study, the design of an automatic ROM-Exercise machine that is constructed witha planar multililnk mechamsm consisting of only revolute pairs is investigated. Namely, equations thatdetermine the minimum moving spaces and relative positions of link required to construct the legmechanism are formulated with consideration of transform functions. For the leg mechanism that isconstructed with a planar eleven-link mechanism, arrangements of each link and optimum linkprofiles avoided mutual interferences among moving links are determined wb consideration of therelative locations of each link in the same plane during a cycle of motion of the mechanism. Based onthe above analytical results, an automatic ROM-Exercise machine that performs within a minimum moving spaces is proposed as a prachcal example. ms study is carried out as part of the students'computcr education to the graduation thesis, in order to improve their creativity and machine designtechnology skills in coniunction with educational advantages. Significam educational results areobtained by using the design techniques mentioned above.

From Nowhere Pioneer a New Path and Be of One Mind to Ascend the High——Profile of the Space Materials Research at Northwestern Polytechnical University

At the end of 2001 National Natural Science Foundation of China (NSFC) organized a laboratory evaluation for Creative Research Groups, a pilot program launched in 2000, in the northwestern area of China and the evaluating team was deeply impressed by a young group, around 30 of average age, with their work and achievements, with their effort in pursuit of scientific truth and with their teamwork spirits. They all acknowl-

The impact of space environment on gene expression in Arabidopsis thaliana seedlings

One of the important questions in space biology is the mechanisms underlying plant responses to an outer space environment,i.e.,how gene expression is altered in space.In this study,the transcriptome of Arabidopsis thaliana seedlings was analyzed as a part of Germany SIMBOX(science in microgravity box)spaceflight experiment on Shenzhou 8 spacecraft.This experiment involved the following treatments:spaceflight with microgravity(Fμg),spaceflight with 1g centrifugal force(F 1g),and ground 1g control(G 1g).Gene chips were used to screen gene expression differences in Arabidopsis thaliana seedlings among these treatments.Microarray analysis revealed that 621 genes were differentially expressed in samples Fμg vs.G 1g,249 genes in samples F 1g vs.G 1g,and 368 genes in samples Fμg vs.F 1g.Gene ontology analysis indicated that the genes were involved in metabolism of stress response,gravitropic response,and DNA damage and repair,suggesting that plants adjust these metabolic pathways to space environmental stress,microgravity,and radiation.