Theoretical analysis on the deformation characteristics of coal wall in a longwall top coal caving face

Against the background of analyzing coal wall stability in 14101 fully mechanized longwall top coal caving face in Majialiang coal mine,based on the torque equilibrium of the coal wall,shield support and the roof strata,an elastic mechanics model was established to calculate the stress applied on the coal wall.The displacement method was used to obtain the stress and deformation distributions of the coal wall.This study also researched the influence of support resistance,protective pressure to the coal wall,fracture position of the main roof and mining height on the coal wall deformation.The following conclusions are drawn:(1) The shorter the distance from the longwall face,the greater the vertical compressive stress and horizontal tensile stress borne by the coal wall.The coal wall is prone to failure in the form of compressive-shear and tension;(2) With increasing support resistance,the revolution angle of the main roof decreases linearly.As the support resistance and protective force supplied by the face guard increases,the maximum deformation of the coal wall decreases linearly;(3) As the face approaches the fracture position of the main roof,coal wall horizontal deformation increases significantly,and the coal wall is prone to instability;and(4) The best mining height of 14101 longwall face is 3.0 m.

Measuring 3D face deformations from RGB images of expression rehabilitation exercises

Background The accurate(quantitative)analysis of 3D face deformation is a problem of increasing interest in many applications.In particular,defining a 3D model of the face deformation into a 2D target image to capture local and asymmetric deformations remains a challenge in existing literature.A measure of such local deformations may be a relevant index for monitoring the rehabilitation exercises of patients suffering from Par-kinson’s or Alzheimer’s disease or those recovering from a stroke.Methods In this paper,a complete framework that allows the construction of a 3D morphable shape model(3DMM)of the face is presented for fitting to a target RGB image.The model has the specific characteristic of being based on localized components of deformation.The fitting transformation is performed from 3D to 2D and guided by the correspondence between landmarks detected in the target image and those manually annotated on the average 3DMM.The fitting also has the distinction of being performed in two steps to disentangle face deformations related to the identity of the target subject from those induced by facial actions.Results The method was experimentally validated using the MICC-3D dataset,which includes 11 subjects.Each subject was imaged in one neutral pose and while performing 18 facial actions that deform the face in localized and asymmetric ways.For each acquisition,3DMM was fit to an RGB frame whereby,from the apex facial action and the neutral frame,the extent of the deformation was computed.The results indicate that the proposed approach can accurately capture face deformation,even localized and asymmetric deformations.Conclusion The proposed framework demonstrated that it is possible to measure deformations of a reconstructed 3D face model to monitor facial actions performed in response to a set of targets.Interestingly,these results were obtained using only RGB targets,without the need for 3D scans captured with costly devices.This paves the way for the use of the proposed tool in remote medical rehabilitation monitoring.

高转速浮装式机械密封端面变形影响因素分析及优化

Floating mechanical seals play an important part in the high-speed rotating machine,and its face deformation will lead to seal failure,also directly affects the device operation performance and service life.In this paper,based on the finite element method,a two-dimensional model of the thermal coupling numerical analysis high speed floating mechanical seal was established,and the influence of different parameters such as rotating speed,pressure,temperature and axial compression force on the deformation of seal face is analyzed.It is found that the dynamic and static face deformation increases exponentially with the increase of rotational speed.At high speed,with the increase of working pressure and temperature,the sealing face deformation increases linearly.When the working pressure reaches 8MPa,the sealing face is in dynamic balance,and no further deformation occurs.Under the condition of high speed and negative temperature difference,the deformation of the sealing end face is positive,with the increase of the axial compression force,the end face shrinked inward,and the deformation rate sudden decrease when the force reaches 4MPa.On the contrary,while the temperature difference is positive,the deformation of the seal end face is negative,and the end face expands outward,meanwhile the expansion of deformation are posi-tively correlated with the axial compression force.According to the analysis results,the control optimization method of the end face deformation is put forward,and the accuracy of the numerical analysis results is verified by the high-speed floating mechanical seal test platform,which provides theoretical guidance for the design and use of high-speed floating sealing ring.

Mechanical Deformation of Ship Stern-Shaft Mechanical Face Seals

In ship propeller shaft systems, the shaft seal is a mechanical face seal, which includes a sta-tionary metal seal ring and a rotating ring. The seal faces are deformed with different loads. The deformation of the seal faces affects the performance of mechanical face seals, which leads to water leakage, so the seal face deformation must be analyzed. A mechanics model with deformation equations was developed to describe ship stern-shaft seals. An example was given to verify the deformation equations. The solution of the deformation equations gives a theoretical basis for the analysis of seal leakage and improvements of seal structures.