Influenced by the dynamic pressure of the front abutment pressure and the lateral abutment pressure, large deformation of surrounding rock occurs advancing working face in the entry heading adjacent to the active longwall mining face. Based on the cause analysis of entry large deformation, a new technology was put forward to solve the problem, and the designing method of drilling hole parameters for directional hydraulic fracturing was formed. Holes are drilled in the entry or in the high drainage entry to a certain rock layer over the adjacent working face, hydraulic cutting or slotting at the bottom of a borehole were also applied in advance to guide the hydraulic fractures extend in expected direction, through which the hard roof above the coal pillar can be cut off directionally. As a result, the stress concentration around the entry was transferred, and the entry was located in a destressing area. The field test at Majialiang coal mine indicates that the propagation length of cracks in single borehole is more than 15 m. After hydraulic fracturing, the large deformation range of the entry is reduced by 45 m, the average floor heave is reduced by 70%, and the average convergence of the entry’s two sides is reduced by 65%. Directional hydraulic fracturing has a better performance to control the large deformation of the dynamic pressure of the entry heading adjacent to the advancing coal face. Besides, it can improve the performance of the safety production.

Inter-turn short circuit (ITSC) is a frequent fault of interior permanent magnet synchronous motors (IPMSM). If ITSC faults are not promptly monitored, it may result in secondary faults or even cause extensive damage to the entire motor. To enhance the reliability of IPMSMs, this paper introduces a fault diagnosis method specifically designed for identifying ITSC faults in IPMSMs. The sparse coefficients of phase current and torque are solved by clustering shrinkage stage orthogonal matching tracking (CcStOMP) in the greedy tracking algorithm.The CcStOMP algorithm can extract multiple target atoms at one time, which greatly improves the iterative efficiency. The multiple features are utilized as input parameters for constructing the random forest classifier. The constructed random forest model is used to diagnose ITSC faults with the results showing that the random forest model has a diagnostic accuracy of 98.61% using all features, and the diagnostic accuracy of selecting three of the most important features is still as high as 97.91%. The random forest classification model has excellent robustness that maintains high classification accuracy despite the reduction of feature vectors, which is a great advantage compared to other classification algorithms. The combination of greedy tracing and the random forest is not only a fast diagnostic model but also a model with good generalisation and anti-interference capability. This non-invasive method is applicable to monitoring and detecting failures in industrial PMSMs.

In this study, a pilot-scale subsurface wastewater infiltration system (SWIS) was deployed to study landscape water treatment. The goal of the study was to investigate the effects of hydraulic loading on pollutant removal and the spatial distribution of biofilm properties in SWIS. Results showed that the efficiencies of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal degraded as hydraulic loading increased. Furthermore, quantities of the biofilm properties parameter s increased with the hydraulic loading. Polysaccharide and protein levels ranged from 560 to 1110 μg/g filler and 60 to 190 μg/g filler, respectively, at a hydraulic loading of 0.2 m/d. At a hydraulic loading of 0.4 m/d, the quantities of polysaccharide and protein ranged from 1200 to 3300 μg/g filler and 80 to 290 μg/g filler, respectively. Biofilm intensity and biofilm activity per unit weight decreased with the increase in hydraulic loading.

This study presents the indoor soundscape framework in detail by describing the variables and factors that form an indoor soundscape study. The main objective is to introduce a new indoor soundscaping framework and systematically explain the variables that contribute to the overall evaluation of an indoor soundscape. Hence, the dependencies of physical and psychoacoustical factors of the sound environment and the spatial factors of the built entity are statistically tested. The new indoor soundscaping framework leads to an overarching evaluation perspective of enclosed sound environments, combining objective room acoustics research and noise control engineering with architectural analysis. Therefore, it is hypothesised that case spaces with certain plan organisations, volumetric relations, and spatial referencing lead to differentiated sound pressure level (SPL) and loudness (N) values. SPL and N parametric variances of the sound environments are discussed through the statistical findings with respect to the architectural characteristics of each library case space. The results show that the relation between crowd level variances and sound environment parametric values is statistically significant. It is also found that increasing the atrium height and atrium void volume, the atrium’s presence as a common architectural element, and its interpenetrating reference and domain containment results in unwanted variances and acoustic formations, leading to high SPL and N values.

This communication reports detection of somaclonal variation among tissue culture-raised plants of Amorphophallus rivieri Durieu, an economically important crop in China, with high content of glucomannan in its corms. A population of regenerated plants was obtained from a single donor plant of A. rivieri via corm organogenesis, and 28 plants were randomly selected as a representative sample and subjected to analysis of somaclonal variation using inter-simple sequence repeat (ISSR) markers. Of the 26 ISSR primers screened, 13 gave distinct and reproducible band patterns, yielding 131 bands with an average of 10.1 bands per primer. Ten primers were polymorphic and generated 16 polymorphic bands with 12.2% mean polymorphism. Based on the ISSR data from the regenerated plants and the donor plant, Jaccard's similarity coefficients were calculated; they ranged from 0.961 to 1.000 with a mean of 0.982. A dendrogram was constructed using the unweighted pair group method with arithmetic mean (Upgma); it showed that a majority of regenerated plants (including the donor plant) clustered closely, with a mean similarity coefficient of 0.987. Low somaclonal variation observed in the regenerated plants indicates that rapid propagation of A. rivieri via corm organogenesis is a practicable method with a low risk of genetic instability.

A novel in-phase disposition (IPD) SPWM pulse allocation strategy applied to a cascaded H-bridge (CHB) converter is presented in this paper. The reason causing the power of the CHB converter imbalance is analyzed according to the traditional structure, the conception of power imbalance degree is introduced and the principle of the novel in-phase disposition SPWM allocation strategy is deduced in detail. The new pulse allocation scheme can ensure the power balance in 3/4 cycles through interchanging the PWM pulse sequence of the different CHB cell, meanwhile it makes the full advantage of the IPD control strategy, lower the total harmonic distortion (THD) of line voltage compared to a carrier phase shifted (CPS) control strategy, which is verified by theoretical derivation. A seven-level cascaded inverter composed by three H-bridge cells is taken as the exam- ple. The simulation and experiment is performed. The results indicate the validity of the analysis and verify the effectiveness of the proposed SPWM allocation strategy.

A robust Kalman filter improved with IGG (Institute of Geodesy and Geophysics) scheme is proposed and used to resist the harmful effect of gross error from GPS observation in PPP/INS (precise point positioning/inertial navigation system) tightly coupled positioning. A new robust filter factor is constructed as a three-section function to increase the computational efficiency based on the IGG principle. The results of simulation analysis show that the robust Kalman filter with IGG scheme is able to reduce the filter iteration number and increase efficiency. The effectiveness of new robust filter is demonstrated by a real experiment. The results support our conclusion that the improved robust Kalman filter with IGG scheme used in PPP/INS tightly coupled positioning is able to remove the ill effect of gross error in GPS pseudorange observation. It clearly illustrates that the improved robust Kalman filter is very effective, and all simulated gross errors added to GPS pseudorange observation are successfully detected and modified.

With the continuous increase of output power ratings, multi-phase (multichannel) interleaved power factor corrector (IPFC) is gradually employed in domestic and commercial inverter air-conditioners. IPFC can solve several main problems, such as power rating increase, power device selection, input current ripple reduction as well as inductor on-board mounting. But for a multi-phase IPFC, the key problem is that it should show rapid dynamic responds and good current sharing capability, so in this paper the aim is to improve the dynamic performance and current sharing capability by means of passivity control theory. Considering the power circuit topology of a four-phase IPFC, an EL (Euler-Lagrange) mathematical model is established when the IPFC operates in continuous conduction mode (CCM). Then the passivity of the four-phase IPFC is proved, and the passivity-based controller using the state variables feedback and damping injection method is designed. The proposed control scheme, which is easy to control and needs no proportion integral controller, has strong robustness on disturbance from singlephase AC input voltage, the load as well as the parameters of the employed devices. Even in wide-range load condition, the mains current has a fast dynamic response and the average output voltage almost keep unchanged. As a result, the main functions of the four-phase IPFC are implemented including nearly unitary power factor and constant DC output voltage. Meanwhile, the four-phase IPFC acquires an excellent current sparing effect after using passivity-based controller. The above analysis has been proved with simulated results by means of MATLAB/SIMULINK and experimental results, showing that the passivity-based IPFC controller has superior performances and feasibility.

Real-time monitoring of deformation of large structure parts is of great significance and the deformation

of such structure parts is often accompanied with the change of curvature. The curvature can be obtained

by measuring changes of strain, surface curve and modal displacement of the structure. However, many

factors are faced with difficulty in measurement and low sensitivity at a small deformation level. In order

to measure curvature in an effective way, a novel fibre Bragg grating (FBG) curvature sensor is proposed,

which aims at removing the deficiencies of traditional methods in low precision and narrow adjusting. The

sensor combines two FBGs with a specific structure of stainless steel elastomer. The elastomer can transfer

the strain of the structure part to the FBG and then the FBG measures the strain to obtain the curvature.

The performed simulation and experiment show that the sensor can effectively amplify the strain to the

FBG through the unique structure of the elastomer, and the accuracy of the sensor used in the experiment is

increased by 14% compared with that of the FBG used for direct measurement.

In order to calibrate the stripe precision of a leveling rod, an automatic laser interferometer and a vision measurement system were designed by Xi’an University of Technology in China. The rod was driven by a closed-loop control and the data were collected at the stop state to ensure precision. The laser interferometer provided not only the long distance data but also a position feedback signal in the automatic control loop. CCD camera and a vision measurement method were used to inspect the stripe edge position and defect. A pixel-equivalent self-calibration method was designed to improve precision. ROI (regions of interest) method and an outline tracing method were designed to quickly extract multiple stripe edges. A combination of the image data with the interferometer data reduces control difficulty and ensures the measurement accuracy. The vision measurement method reached sub-pixel precision and the defective edges were reported. The system can automatically calibrate a stripe leveling rod with a high degree of efficiency and precision.