Physical Model Experimental Study on the Coalface Overburden Movement Law on the End-slope of an Open-pit Mine

Due to technology and safety limitations, the amount of coal resources overlying slopes in open pit coal mines is immense. In recent years, this problem has gradually attracted the attention of researchers. How to realize the efficient recovery of the side overburden resources with the premise of ensuring the stability and safety of the slope has become an important topic for the development of opencast mining technology in China. To study the yield failure characteristics of coal pillars and the rock mass migration law of the end slope mining field under the mining condition of the end slope shearer, 2D/3D, integrated, simulation experimental equipment is developed based on similarity theory and efficient region theory. This equipment overcomes the technical problem that the internal failure of the rock mass is invisible and that deformation data are not easily obtained during the simulation of end slope coal mining on an existing experimental platform. Based on the engineering geological conditions of the Ordos mining area in China, a typical engineering geological model of the slope near the horizontal condition is constructed to simulate the process “formation of mining cave group -failure of support coal pillars - instability of slope rock mass”. Based on laser positioning technology and multiangle, oblique photography technology, a panoramic phase 3D laser scanner, high-resolution digital camera and deep space micromonitoring system are comprehensively employed to carry out the whole process tracking monitoring and analysis of the deformation and failure of the supporting coal pillars and slope rock mass. The experiment is verified by numerical simulation. The results show that under the experimental conditions, with an increase in mining cave depth, the vertical stress of the supporting coal pillar increases linearly. At a certain distance before reaching the end of the mining cave, the peak value is reached. At this time, the depth continues to increase, and the stress value decreases sharply. The vertical stress gradually decreases to the original rock stress after a certain distance beyond the end of the mining cave. A certain length of supporting coal pillar from the end of the mining cave will never collapse, which is approximately 2.5~3 times the width of the mining cave. The triggering condition of slope deformation and failure is under the combined action of dynamic and static loads. The actual stress of the supporting coal pillar in the deep part of the geometric centre along the slope of the mining cave group is greater than the ultimate stress, and then large discontinuous deformation of multiple adjacent coal pillars around the central coal pillar is caused by compressive shear failure. The boundary of the final collapse plane range of the roadway group is approximately a closed curve formed by two paraboloids, which are axisymmetric with the No. Ⅳ coal pillar and open opposite. The parabola opening in the shallow part of the slope area is small, and the parabola opening in the deep part of the slope area is large. There is a significant space-time correspondence between the failure of supporting coal pillars and the deformation of the slope surface. According to the failure process of the rock mass structure and the movement and deformation characteristics of the slope surface, the slope after failure can be divided into three areas, and the upper part of the slope is the key area of deformation and instability of the overlying rock mass in the end-slope mining field. The research results provide a theoretical basis for scientific monitoring and stability control of slope deformation coal mining conditions in open-pit mines.

STMO-7 Usefulness of NU-KNIT in retractorless surgery for malignant glioma

On the removal of the brain tumor, securing of appropriate working corridor and the maintenance of the visibility are one of the most relevant elements regardless of tumor local existence. This is unchangeable extract in these days when a support apparatus such as navigation system and the nerve monitoring was enriched, and, in the malignant glioma that a tumor border is relatively indistinct, the importance does not change either.At our hospital, I protect the access route by two folds of coating of absorbable hemostat(Surgical NU-KNIT) and neurosurgical patties (Delicot) on the removal of the malignant brain tumor in the brain deep part instead without using as possible fixed retractor for the purpose of securing of working corridor under minimum retraction and extract deep part tumor. In this way, normal real protection, wet maintenance, maintenance of the visibility by the control of the bleeding and pressure reduction of the neighborhood organization extracting are provided, and postoperative function recovery gets an early impression. About a method of the securing of working corridor at our hospital, I inspect the usefulness and limit by showing representative cases and want to have an opinion, criticism.

A computational study on the optimization of transcranial temporal interfering stimulation with high-definition electrode using unsupervised neural network

Transcranial temporal interfering stimulation (tTIS) can focally stimulate deep parts of the brain, which are related to specific functions, by using beats at two high AC frequencies that do not affect the human brain. However, it has limitations in terms of calculation time and precision for optimization because of its complexity and non-linearity. We aimed to propose a method using an unsupervised neural network (USNN) for tTIS to optimize quickly the interfering current value of high-definition electrodes, which can finely stimulate the deep part of the brain, and analyze the performance and characteristics of tTIS. A computational study was conducted using 16 realistic head models. This method generated the strongest stimulation on the target, even when targeting deep areas or multi-target stimulation. The tTIS was robust with target depth compared with transcranial alternating current stimulation, and mis-stimulation could be reduced compared with the case of using two-pair inferential stimulation. Optimization of a target could be performed in 3 min. By proposing the USNN for tTIS, we showed that the electrode currents of tTIS can be optimized quickly and accurately, and the possibility of stimulating the deep part of the brain precisely with transcranial electrical stimulation was confirmed.

How the Earth Recycles

Recycling is not just for plastic. Did you know that the Earth recycles? Recycling happens because the outer part of the planet is made up of large moving pieces of rock. Some of these pieces, called tectonic plates, sink deep down into the Earth. The deeper they go, the more heat and pressure they experience. This causes chemical reactions, including melting of the minerals that make up the rocks. Elements and water trapped inside the melting minerals are released and erupt from volcanoes, returning to the surface. The Earth has recycled! In this article, we present new research on a mineral called lawsonite. Lawsonite only forms in plates that dive into the Earth. Lawsonite has returned to the Earth’s surface in a few rare places where we can collect and analyze it. The composition of elements inside the lawsonite mineral help us understand the deep part of the Earth recycling system.

Research on Performance Evaluation of PPG/Polymer Flooding System

Aiming at the PPG/polymer flooding system developed by Daqing Exploration and Development Research Institute, this paper conducts research on its viscosity increasing, viscosity stability, rheological properties, viscoelasticity and seepage ability. The experimental results show that:PPG has a thickening effect on the system, and the thickening range is between 37% and 66%;the viscosity retention rate of the PPG/polymer system is higher (88%) than the ordinary 25 million polymer solution (75%) ); Under the same shear rate conditions, the apparent viscosity of the PPG/polymer system is higher than 25 million pure polymer; the PPG/polymer system has a resilience effect, and its G’ and G” values are greater than that of a pure polymer solution;PPG/The polymer system can migrate to the deep part of the oil layer and still maintain high seepage resistance, which can realize deep profile control.

A Computational Study On The Optimization of Transcranial Temporal Interfering Stimulation With High-Definition Electrode Using Unsupervised Neural Network

Transcranial temporal interfering stimulation (tTIS) can focally stimulate deep parts of the brain, which are related to specific functions, by using beats at two high AC frequencies that do not affect the human brain. However, it has limitations in terms of calculation time and precision for optimization because of its complexity and non-linearity. We aimed to propose a method using an unsupervised neural network (USNN) for tTIS to optimize quickly the interfering current value of high-definition electrodes, which can finely stimulate the deep part of the brain, and analyze the performance and characteristics of tTIS. A computational study was conducted using 16 realistic head models. This method generated the strongest stimulation on the target, even when targeting deep areas or multi-target stimulation. The tTIS was robust with target depth compared with transcranial alternating current stimulation, and mis-stimulation could be reduced compared with the case of using two-pair inferential stimulation. Optimization of a target could be performed in 3 min. By proposing the USNN for tTIS, we showed that the electrode currents of tTIS can be optimized quickly and accurately, and the possibility of stimulating the deep part of the brain precisely with transcranial electrical stimulation was confirmed.

Difference in Movement between Superficial and Deep Parts of the Infrapatellar Fat Pad during Knee Extension

(1): The superficial and deep parts of the infrapatellar fat pat (IFP) have different morphological and functional characteristics. Knee pain often occurs during movement, and it is important to clarify the movement of the IFP during knee joint movement. The purpose of this study is to clarify that the movement of the superficial and deep parts of the IFP are different during knee extension in vivo using ultrasonography (US). (2): US was performed on 15 knees of 15 healthy adults. The probe was placed longitudinally at the center of the patellar tendon and the IFP was imaged. Measurements were taken during active extension of the knee from 90 degrees to 10 degrees of knee flexion at a rate of 30 times/min. The captured US videos were analyzed using Flow particle image velocimetry (Flow PIV) fluid measurement software. The region-of-interest (ROI) was set at the superficial part and the deep part of the IFP, and the flow velocity was calculated for each. (3): The flow velocity of the deep part (1.37 ± 0.13 cm/s) of the IFP was significantly faster than that of the superficial part (0.80 ± 0.23 cm/s). (4): Our results show that the flow velocity of the IFP is different between the superficial and deep parts and that US may be a better assessment tool for the movement of the IFP.

Flow Field Investigation in Draft Tube of Francis Turbine at Off-Design Operation Using a Vortex Identification Algorithm

At off-design operations, flow instabilities such as vortex breakdown, reverse flows, and stagnant regions are observed in Francis turbines. The present work shows the numerical flow field investigations of a Francis turbine at two different part loads (PL) by employing a vortex identification algorithm. The analysis has been performed at various locations in the draft tube by extracting the velocity fields at different time steps of the simulation. The first operating point involves a fully developed rotating vortex rope (RVR) in the draft tube, which precesses at a frequency of 0.28 times of the runner rotation. The present algorithm is able to identify the regions along with the eccentric local rotation center. The second operating regime shows characteristics of deep part load with central solid body rotation in the draft tube flow field. The results show highly swirling flows with very low axial velocity. The flow is confined primarily near the walls. The analysis shows that the extent of stagnation region at deep part load is more and no inner shear layer is present as compared to the part-load operation. The spatial harmonic decomposition (SHD) of the pressure data is also performed to evaluate the synchronous and asynchronous components of pressure pulsations.