Search

Gas overruns and explosions often occur in coal mining. To deal with this problem, the spatial structure model of a new non-ventilation excavation system is constructed. Combined with the model, a simulation experiment is conducted and the variations in gas concentration in each area of the system with variations in the amount of gas emission, drainage, and nitrogen curtain outlet velocity are obtained. The effectiveness of the gas barrier by the combined action of the gas drainage and nitrogen curtain is verified. This study provides the experimental basis for solving the problem of gas overruns and explosions, and is of great significance for realizing safe, efficient, and rapid excavation.

The discussion of stress evolution law and failure characteristics of rock mass in mining floor above confined water is the key to control the floor water inrush in deep mining. Based on analyzing the strike support pressure of working face, the mechanical model of coal floor above the confined water was established. Then, vertical, horizontal and shear stress distribution maps and the failure range morphological map of mining floor were calculated based on data processing software Origin. Then, with the similar simulation test bed for water inrush from coal seam floor, the fluid solid coupling simulation material was selected, and the stress evolution law and failure characteristics of coal seam mining floor were improved. The results showed that the vertical stress contour is a “semi-elliptical” shape distribution and the greater the floor depth, the smaller the affected degree, but the influenced range increased. The higher shear stress zone occurred in the vicinity of working face coal wall. The failure range morphological map of mining floor was approximately a spoon shape and maximum failure depth was 14.0 m based on the mechanical theory. The maximum failure depth of the floor was 13.4 m based on the similar simulation experiment. So, the experimental results are in agreement with the theoretical results. The results in this paper can provide theory basis for safety mining above confined water.

Since 2015, China has strengthened the control of NO x emissions, and put forward higher requirements for the denitrification efficiency of the original SCR. In the SCR denitration system of coal-fired power plants, the problems of high ammonia escape rate are common. The traditional automatic control system must be optimized to solve these problems. Automatic controlling for ammonia gas supply valve of denigration system is also one of the common problems during debugging. Mismanagement will bring excess ammonia spray, equipment operating safety hazard and the increase in the operating personnel workload easily. This paper describes the debugging process of ammonia gas supply valve. The suggestions for improvement is proposed to adjust the valve control strategies and reduce dead-zone valves.

Mining of the No. 15 seam in the Gushuyuan coal mine is threatened by water inrush from the underlying Ordovician limestone aquifer. Water pressure and yield of the aquifer, the equivalent thickness of the water-resisting layer(s), and the properties of geologic structures are the major factors that control water inrush. The water inrush risk was evaluated using the vulnerability index (VI) method, which couples GIS with the analytic hierarchy process. Comparing the results with that of the traditional water inrush coefficient method in a specific mining area clearly showed the advantage of the VI method, especially in mines underlain by a thin water-resisting layer.

Mine water accident due to the mining above confined water is one of the main factors which affects and threatens safety in the coal production, especially for deep mine. Finding out the mine hydrogeological conditions, deepening the research of water inrush mechanism, and taking the effective safety measures of water bursting prevention, are all the key issues of mining under water pressure safely. Based on fractured rock mass equivalent continuum theory, according to drilling imaging method and water pressure test in borehole, in this paper we focus on discussing the water inrush of the floor rock , determining the floor rock permeability tensor with correction method and simulating the floor inrush problem by coupling stress field and seepage field theory and using anisotropic seepage model with FLAC3D. The results show that, the depth of destroyed floor in normal area and fractured zone in fault are about 30m and 58m respectively. According to empirical equation and numerical simulation, we get the results that the effective protection layer thicknesses are 82m and 115m respectively, and it has presented dangers in fault fractured zone based on the water bursting coefficient method.

Based on equivalent continuum media theory of fractured rock mass, the author got the permeability tensor of floor strata in some mine according to core logging method, drilling imaging method and boring water injection method, and determined the floor rock permeability tensor using correction method. The author simulated the floor inrush problem by coupling fluid-solid theory and anisotropic flow model with FLAC3D software. The result shows that, the destroyed depth of floor and the confined water rising height are all slight when the coal mining workface is 150m apart from the fault, but they increase obviously when the coal mining workface is 30m apart from the fault, and are extremely easy to get through and casue water inrush through fault.

Summary Background: Both over- and undercorrection can occur in up to 10–15% of strabismus surgeries. Use of adjustable suture technique and an intraoperative awake test may decrease the incidence of over- or undercorrection. In this study, we investigated the ability to provide optimal conditions for intraoperative awake strabismus suture adjustment in children by means of target-controlled infusions (TCI) of propofol and remifentanil propofol compared with propofol and sufentanil. Methods: Forty-six ASA I–II patients undergoing strabismus surgery with intraoperative awakening were randomly assigned to anesthesia by TCI of propofol + sufentanil group (group SF) or propofol + remifentanil spontaneous breathing. Propofol was discontinued, and concentrations of the opioid TCIs were reduced to enable awake assessment of the mobility and position of the eye. Changes in intraocular pressure, respiratory function, hemodynamics, awakening time, and awaking quality were compared between the two groups. The degrees of sedation and analgesia were evaluated through the assessment of alertness and sedation scores (OAA/S) and visual analog scale scores (VAS). Results: There was no significant difference in intraocular pressure at three sampling points between two groups (P > 0.05). The heart rate (HR) and mean arterial blood pressure (MAP) in group SF were significantly lower than group RF during laryngeal mask insertion (P 0.05). There was no significant difference in the target effect-site concentration of propofol at T1–T10 between the groups (P > 0.05). The wake-up times in group SF were significantly longer than in group RF (P 0.05). Conclusion: Propofol combined with sufentanil or remifentanil can be suitable for planned intraoperative awakening for an adjustable suture technique in pediatric patients during strabismus surgery. Remifentanil has quicker wake-up time; however, sufentanil demonstrated an advantage in terms of better analgesia, more stable hemodynamics, and improved qualify of awakening.

Dexmedetomidine is a highly selective alpha-2 adrenergic agonist that has a sedative effect and has been shown to reduce anesthetic requirements. It also has a sympatholytic effect, which may prove useful when used to blunt the sympathetic surge during intubation and extubation. However, its effects on intraocular pressure, hemodynamic stability, attenuation of extubation response, and emergence agitation remain unclear for pediatric patients undergoing vitreoretinal surgery. We focused on these effects in this study.Sixty ASA I-II patients undergoing vitreoretinal surgery, were anesthetized with sevoflurane 1-2% end-tidal concentration in oxygen supplemented by remifentanil 0.2 μg/kg/min. Intraocular pressure was measured after inhalation of sevoflurane (IOP(Baseline)) and 10 min after intravenous administration of dexmedetomidine 0.5 μg/kg or normal saline (IOP(10min)), after induction of anesthesia. Blood pressure and heart rate were recorded every 5 min during surgery. The incidence and severity of coughing and emergence agitation and untoward airway events after extubation, for example breath holding, laryngospasm, bronchospasm, and oxygen desaturation, were assessed. Extubation time and emergence time were also documented.There was no significant difference in intraocular pressure at the two time points between the groups (p 0.05). In both groups mean arterial pressure and heart rate decreased from baseline after anesthetic induction (p 0.05). The increase from intraoperative values in mean arterial pressure and heart rate associated with extubation was diminished in the dexmedetomidine group compared with the control group (p 0.05). Coughing after extubation was less common (10 vs. 21) and less severe (3 moderate and 7 minimal; vs. 2 severe, 7 moderate and 12 minimal) in the dexmedetomidine group than in the control group (p 0.05). There were no significant differences between the groups in time to emergence or extubation (p 0.05). The dexmedetomidine group had a lower incidence of emergence agitation than the control group (10 vs. 43.3%, p 0.05). The incidence of breath holding, laryngospasm, bronchospasm and oxygen desaturation was not significantly different between the groups (p 0.05).Dexmedetomidine 0.5 µg/kg had no effect on intraoperative hemodynamics or intraocular pressure, but attenuated the hemodynamic response to extubation and diminished emergence agitation in pediatric patients undergoing vitreoretinal surgery.

The GlideScope (GS) video laryngoscope has been proven to be a suitable intubating device for a predicted difficult intubation. Patients with ankylosing spondylitis (AS) presented with particularly challenging airway management problems to the anesthesiologists. The benefits of using a GS in these patients have not been fully explored. The aim of this study was to evaluate the effectiveness of the GS, in comparison with the Macintosh laryngoscope, when performing nasotracheal intubation in patients with AS under general anesthesia.A total of 60 ASA I-II patients with AS were randomly assigned to undergo nasotracheal intubation using either the GS or the Macintosh laryngoscope. Preoperative airway assessments were performed in an attempt to predict the difficulty of tracheal intubation. Duration and number of intubation attempts, success rates, number of optimization maneuvers, Cormack and Lehane grades, Percentage of Glottic Opening (POGO) scores for each attempt, and difficulty of device use (VAS difficulty scores) were recorded. Complications associated with intubation were also recorded.The rate of successful nasotracheal intubation was lower with the Macintosh laryngoscope (70%) compared with the GS (96.7%). In comparison with the Macintosh laryngoscope, the GS significantly reduced the intubation difficulty score, duration of tracheal intubation attempts, need for optimization maneuvers, and improved the Cormack and Lehane grade obtained during laryngoscopy.The GS reduced the difficulty of tracheal intubation and provided a better laryngoscopic view with higher overall success rates and shorter duration of intubation attempts than the Macintosh laryngoscope. In our study, the GS proved to be a better alternative in most cases, compared with the Macintosh laryngoscope, for intubating AS patients who preferred their airway management under general anesthesia.

As a special education mode of graduate students in the development stage of exploration, the master of engineering education has distinct characteristics as applicability, practicality and so on. Based on the theory of WBS flow chart, this article has made establishment and analysis about the grading flow chart for the master of engineering’s training process, constructed the “Quaternity” master of engineering talents dynamic training mode system. This article realized the information platform function of master of engineering’s teaching and management system by using Java web technology and My SQL database programming technology.

In order to realize the systematization, informatization and high efficient of the petrochemical enterprise’s safety management, with the safety management principle as the theoretical basis and using the ASP.Net technology, this article researched and analyzed the system design of the petrochemical enterprise’s safety management informatization system and the function of each module, realized the information platform function of the petrochemical enterprise’s safety management informatization by using Java web technology and My SQL database programming technology.