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Facing the demand of autonomous path correction of the road-header working underground, a control law was designed and simplified based on the position and orientation deviation model of the road-header against its aimed walking trajectory.Reasonable Lyapunov function is constructed to prove the convergence of the position and orientation deviation that resulted from the designed control law.Based on a certain real time position and orientation detection strategy for the road-header, the possible errors exist during posture adjustments are summarized and classified into two parts: one is the main execution error of the road-header and it is presented by the slip rate of tracks; the other is the main observation error and it is identified as the position and orientation measurement errors.This paper proposed to take advantages of the statistical characteristics of these errors, which is obtained by a certain number of experiments or deductions instead of rigorous theoretical analysis.The SVD-unscented Kalman Filtering is used to modify the commands that are given originally by the controller so as to deduce and reduce the influence of process error and observation error in the process of position and orientation adjusting.The simulation results show that the proposed path tracking control strategy can effectively realize the transition of the road-header to the target roadway in limited adjustment period, and the corresponding recommended speeds of the driving wheels vary continuously and stably in the whole process.The negative influence of process error and observation error is effectively weakened by commands modification based on SVD-unscented Kalman Filtering.The obtained moving trajectory of the road-header coincides with the planned path very well during the adjustment, which is of great repeatability.This proves that the proposed strategy is of great potential to be applied experimentally in underground real road heading scenario.

According to the working characteristics of the underground road-header, path planning and movements scheduling for path correction of the road-header is formulated.The position and orientation errors of the road-header during working are also presented based on its kinematic model.Taking the working speed and turning angular speed as control inputs, the control law is designed and simplified to ensure the convergence of position and orientation errors based on the theory of sliding mode control.The stability of the proposed control system is proved by using the principle of Lyapunov.The corresponding simulations show that the designed tracking control enables the road-header to come back to the aimed path within limited adjusting steps, The whole scheduling scheme introduced for path correction is reasonable and feasible, and can provide a positive foundation for further study of automatic mining in the coal industry.

In order to optimize the energy efficiency of a fixed-wing unmanned aerial vehicle(UAV) mobile relaying system, this paper proposes an energy-efficient flight scheme, where a straight trajectory is used, and the decode-andforward(DF) strategy and the time-division duplex(TDD) mode are employed. With the data received and forwarded at the relay sideseparately, the energy efficient optimization problem is transformed into two sub-problems. An iteration algorithm using the Dinkelbach method optimizes the UAV relay acceleration and figures out the optimal solution of the energy efficiency problem. The effectiveness of the algorithm is verified through numerical simulations.Simulation results show that compared with the traditional UAV relay flight scheme, the proposed scheme can significantly improve the energy efficiency performance. As the distance between the source and destination nodes increases,the performance advantage becomes more evident.

At present, detection error of pitch angle of roadheader is mainly compensated by manually controlling front blade and rear support of roadheader, the compensation range is very limited, and the efficiency, control precision and automation degree are low. In view of the above problem, mathematical model of pitch angle and actuator of boom roadheader were established, and the method was determined that adjusting position and posture of boom roadheader by using PID controller to control displacement of front shovel and rear support of the roadheader. AMESim was used to establish complete hydraulic model of actuator of the roadheader. The AMESim simulation shows that response time of the system is less than 3 s and the control error of hydraulic cylinder displacement is less than 2 mm, so the basic performance of the pitch angle control system is verified. The Simulink simulation results verify that the pitch angle control system has short response time, small tracking error, and good dynamic tracking performance.

In view of problem that it is difficult to extract vibration signal and carry out fault diagnosis of coal mine electromechanical equipment, intrinsically safe mine-used portable vibration recorder was applied to collect vibration signal of shearer cutting unit, and spectrum analysis and Hilbert demodulation technique were used to demodulate fault characteristic frequency of the vibration signal, so as to determine fault location, which provides reliable basis for fault diagnosis and maintenance of shearer.

Vibration monitoring test of underground belt conveyor gear reducer was conducted by use of vibration recorder. Analysis of changing trend and power spectrum of time-domain characteristic index of on-site vibration data indicates that input shaft of the gear reduer has severe wear and gear tooth breakage.Overhaul results verify correctness of the above analysis and validity of the data sampled by the recorder.

In view of problem that vibration signal of underground large equipments is difficult to be collected, a mine-used signal conditioning device of vibration acceleration sensor was designed. It introduced selection design of vibration acceleration sensor, design of power module, exciting circuit and filtering circuit of conditioning board of vibration signal and protection design of the device. The test result validates reliability and practicality of the device.

In this paper, seismic behavior of the shear link "fuse" used in the steel coupling beam was examined through quasi-static tests on twelve link specimens. The test variables included the steel type for web, link length ratio, stiffener configuration, and loading protocol. All link specimens yielded in shear, followed by two types of failure modes, i. e., link web fracture and fracture at the weld connecting link flange to end plate. The overstrength factors of the link specimens reached approximately 1.86, higher than a value of 1.5 recommended by Popov et al. The specimens had an inelastic rotation of approximately 0. 15 rad, much larger than 0. 08 rad required by the AISC 341-10 provisions. Using the low yield steel LY225 instead of Q235 steel for web increased the inelastic rotation of the links by 23% and the cumulative plastic rotation by 52%. Setting stiffeners on one side of the web only or on both sides of webs made very limited difference on the behavior of the links. Increase of the stiffener spacing led to early-stage web buckling and obvious strength degradation. The low-yield steel links are thus recommended to follow the requirements of stiffener details specified by AISC 341-10 and GB 50011-2010. The axial displacement that occurred during the specimens were subjected to cyclic shears included the geometrical displacement and inelastic axial deformation induced by shears. The inelastic axial deformation was found to be proportional to the cumulative plastic rotation of the links. [ABSTRACT FROM AUTHOR]

In variable rate networks, the source transmits different number of message packets to sinks at different time. If the maximum flow from source to a destination is not less than the information rate, the sink is required to retrieve all the message packets. Focusing on the issue, we deduce the global and local transfer matrix from the data transmission point of view. Moreover, we obtain the conditions of achieve successful communication in variable rate networks and get an approach of how to construct variable rate linear network code. What's more, our method can also be used to construct linear network codes for variable rate networks with link failure and guarantee the robustness of these networks. [ABSTRACT FROM AUTHOR]

Objective To observe the clinical efficacy of zoledronic acid injection in the treatment of senile osteoporosis patients with low back pain. Methods Sixty-one senile osteoporosis patients with low back pain, who were treated in our hospital from September 2011 to May 2012, were selected. All the patients were randomly divided into control group and treatment group. The treatment group had 29 patients, and the control group had 32 patients. Patients in the treatment group received an intravenous drip of 5mg zoledronic acid injection once a year. Sufficient supplementation of water during the treatment was performed, and the medication of non-steroidal anti-inflammatory drugs was also performed simultaneously. Patients in the control group received an intravenous drip of 250ml normal saline instead. All the patients took a long-term oral medication of 600mg Caltrate D twice a day and 0. 25 ug calcitriol once a day. VAS pain scores were evaluated through patients' self-assessment. The function was evaluated through pain assessment, physical examination assessment, and bone mineral density (BMD) detection. Results All the 61 patients, except for 1 patient in the control group died of heart disease during the follow-up period, received 6-9^nonth follow-up, with an average of 7. 8 months. Compared with that in the control group, the VAS scores of low back pain in the treatment group improved significantly (P < 0. 05), and BMD also increased significantly (P < 0. 05). Conclusion The short -term and long-term efficacy of zoledronic acid injection in the treatment of senile osteoporotic low back pain is obvious. The treatment can significantly relieve the pain. Therefore, it is worthy of recommendation in clinical application, but should be used with caution in the treatment of type I osteoporotic patients with low back pain. [ABSTRACT FROM AUTHOR]

This paper presents quasi-static tests of six large-scale steel tube-reinforced concrete (ST-RC) composite column specimens under high axial force ratio. The effects of the number of loading cycles and the volumetric transverse reinforcement ratio on cumulative damage performance of the ST-RC columns were investigated. The test results indicate that the number of loading cycles has minimal effect on the strength capacity of the specimens. The number of loading cycles has limited effect on the deformation capacity for the specimens of which the transverse reinforcement is designed based on the volume of all stirrup-confined concrete, while it obviously affects the deformation capacity for the counterpart specimens of which the transverse reinforcement is designed based only on the volume of the stirrup-confined concrete of RC encasement. When the lateral loading reverses ten cycles at each displacement level, the former specimen shows obviously larger deformation and cumulative energy dissipation capacities than the latter. The ultimate displacement and failure displacement of the former are 25% and 41% larger than those of the latter, and the total cumulative energy dissipated by the former is 2.8 times that of the latter. Allowing for the effect of cumulative damage of structures subjected to ground motions, the recommendation is made that the transverse reinforcement for the ST-RC columns should be designed based on the volume of all stirrup-confined concrete for ensuring adequate deformation capacity of the columns. [ABSTRACT FROM AUTHOR]

This paper proposed an innovative composite wall, named the steel tube-double plate-concrete composite shear wall, which is suited for use in the lower stories of super high-rise buildings. The seismic behavior of the composite walls was examined through results of an experimental research program where five rectangle-shaped wall specimens with a shear span ratio of 2.5 were tested. The test results indicate that the specimens fail in a flexural mode, characterized by local buckling of boundary steel tubes and steel plates, fracture of steel tubes, and compressive crushing of concrete at the wall base. The extent of concrete filled steel tubular (CFST) boundary elements significantly affects the deformation and energy dissipation capacities of the composite walls. The area ratio of steel plate has a minimal effect on the deformation capacity of the wall specimens. The addition of circular steel tubes embedded in the CFST boundary elements leads to an increase in the lateral load-carrying capacity of the composite walls, but it does not increase the wall's deformation capacity. When the CFST boundary element's extent is 0. 2 times the wall's sectional depth and the designed axial force ratio is 0.45, the wall specimen has a yield drift ratio of over 0. 005 rad and an ultimate drift ratio of 0. 030 rad. In addition, simplified formulas used to calculate the flexure strength of the composite walls were proposed. The evaluated results show good agreement with the test results, with errors no more than 10%. [ABSTRACT FROM AUTHOR]

This paper presents seismic retrofit for the single-story brick-wood structure representative of existing rural buildings in Beijing. The retrofitting effectiveness was examined through large-scale shaking table tests on the unretrofitted and retrofitted specimens. The test results indicate that, for the unretrofitted specimen, the front brick columns deform and damage severely when subjected to the longitudinal motions, because large of lateral stiffnesses difference exists between the front and back longitudinal walls. The brick gables experience significant out-of-plane deformation, resulting in diagonal cracks. The unretrofitted specimen is cracked under minor earthquakes, significantly damaged under design basis earthquakes, and approaches to collapse under rare earthquakes. The method of seismic retrofit was proposed based on the test results of the unretrofitted specimen, including the addition of a steel doorframe, steel window frames and steel plate collar beams, and the strengthening of the brick gables and columns by cement mortar reinforced with steel mesh. Shaking table test results show that the retrofit method significantly improves the earthquake-resistant capacity of the brick-wood building structure, and the retrofitted specimen can achieve the design objective of 'operational under minor earthquakes, repairable damage under design basis earthquakes, and collapse prevention under rare earthquakes'. [ABSTRACT FROM AUTHOR]

To study the seismic behavior of composite-sectioned high strength concrete filled steel tubular (CSCFT) columns, quasi-static tests on six specimens were conducted. The test variables included the axial force ratio, wall thickness and width-to-thickness ratio of square steel tube, confinement index of circular concrete filled steel tube (CFT). Test results indicate that the failure mode of the CSCKF column specimens is characterized by wall buckling of square steel tube and crushing of partial concrete between the square steel tube and the circular steel tube within a height of 300mm from the column base. The lateral force-displacement hysteretic loops are plump. At the peak lateral force, the drift ratio of one specimen is a little bit less than 1/100 since it has a design value of axial force ratio close to 1.0, and the drift ratios of other 5 specimens are larger than 1/100. As the wall width-to-thickness ratio of square steel tube reduced, or the confinement index of CFT increased, the initial secant stiffness and the ultimate drift ratio are increased. As the wall thickness of square steel tube increased, the bending strength of specimen under axial compressive force is enhanced. The bending strength of the specimens calculated by the superposition method and by the plane section assumption has good agreement with the test results. [ABSTRACT FROM AUTHOR]