160 results about "Stability parameter" patented technology

The present invention relates to a method and device for improving concealment of frame erasure caused by frames of an encoded sound signal erased during transmission from an encoder (106) to a decoder (110), and for accelerating recovery of the decoder after non erased frames of the encoded sound signal have been received. For that purpose, concealment / recovery parameters are determined in the encoder or decoder. When determined in the encoder (106), the concealment / recovery parameters are transmitted to the decoder (110). In the decoder, erasure frame concealment and decoder recovery is conducted in response to the concealment / recovery parameters. The concealment / recovery parameters may be selected from the group consisting of: a signal classification parameter, an energy information parameter and a phase information parameter. The determination of the concealment / recovery parameters comprises classifying the successive frames of the encoded sound signal as unvoiced, unvoiced transition, voiced transition, voiced, or onset, and this classification is determined on the basis of at least a part of the following parameters: a normalized correlation parameter, a spectral tilt parameter, a signal-to-noise ratio parameter, a pitch stability parameter, a relative frame energy parameter, and a zero crossing parameter.

The present invention relates to a method and device for improving concealment of frame erasure caused by frames of an encoded sound signal erased during transmission from an encoder (106) to a decoder (110), and for accelerating recovery of the decoder after non erased frames of the encoded sound signal have been received. For that purpose, concealment / recovery parameters are determined in the encoder or decoder. When determined in the encoder (106), the concealment / recovery parameters are transmitted to the decoder (110). In the decoder, erasure frame concealment and decoder recovery is conducted in response to the concealment / recovery parameters. The concealment / recovery parameters may be selected from the group consisting of: a signal classification parameter, an energy information parameter and a phase information parameter. The determination of the concealment / recovery parameters comprises classifying the successive frames of the encoded sound signal as unvoiced, unvoiced transition, voiced transition, voiced, or onset, and this classification is determined on the basis of at least a part of the following parameters: a normalized correlation parameter, a spectral tilt parameter, a signal-to-noise ratio parameter, a pitch stability parameter, a relative frame energy parameter, and a zero crossing parameter.

Improved methods and devices are provided for detecting and / or predicting the onset of an undesirable physiological event or neural state, such as an epileptic seizure, to facilitate rapid intervention with a treatment therapy such as neurostimulation or drug therapy. The methods and devices involve monitoring the patient's body temperature, preferably by an implanted temperature sensor, to detect a change in a body temperature parameter over a first time period. The temperature parameter change may comprise an increase or decrease in the patient's body temperature over a first time period, time rate of change of body temperature over a first time period, a moving average temperature over a first time period, an increase or decrease in body temperature exceeding a target temperature over a first time period, an elevated or reduced body temperature over first time period, or a temperature stability parameter over a first time period. The sampling period at which body temperature measurements are made may be changed manually or depending upon a sensed body parameter, including temperature. When a parameter change is detected that exceeds a threshold, neurostimulation therapy is delivered to a neural structure of the patient.

Methods for fragmenting ions in an ion trap are described. These methods involve a) selecting parent ions for fragmentation; b) retaining the parent ions within the ion trap for a retention time interval, the ion trap having an operating pressure of less than about 1×10-4 Torr; c) providing a RF trapping voltage to the ion trap to provide a Mathieu stability parameter q at an excitement level during an excitement time interval within the retention time interval; d) providing a resonant excitation voltage to the ion trap during the excitement time interval to excite and fragment the parent ions; e) providing a non-steady-state pressure increase of at least 10% of the operating pressure within the ion trap by delivering a neutral gas into the ion trap for at least a portion of the retention time interval to raise the pressure in the ion trap to a varying first elevated-pressure in the range between about 6×10-5 Torr to about 5×10-4 Torr for a first elevated-pressure duration; and f within the retention time interval and after the excitement time interval, terminating the resonant excitation voltage and changing the RF trapping voltage applied to the ion trap to reduce the Mathieu stability parameter q to a hold level less than the excitement level to retain fragments of the parent ions within the ion trap. The excitation time interval and the first elevated-pressure duration substantially overlap in time.

The invention relates to an automobile stability parameter test bench and a test method using the same, which are used for integrally testing automobile mass parameters, centroid position parameters and anti-tipping angle parameters. The automobile stability parameter test bench of the invention comprises a measuring platform, four platform balances, platform supporting columns, a foundation, three hydraulic cylinders, an inclination angle measuring device, hydraulic sensors, a pump station and a computer, wherein the four platform balances are installed on the measuring platform and are supported by a weighting sensor; the supporting points of the platform supporting columns are distributed in rectangular peaks; the foundation is used for bearing the supporting columns and the platform; the three hydraulic cylinders are arranged between the platform and the foundation and can enable the platform to incline longitudinally or laterally; the inclination angle measuring device is fixed on the platform; the hydraulic sensors are installed in the positions of the upper cavity and the lower cavity of the two hydraulic cylinders which enable the platform to incline longitudinally; the pump station is connected with the hydraulic cylinders; and the computer is used for acquiring and calculating the data of the weighing sensor, the oil pressure of the hydraulic cylinders and the inclination angle data of the platform. Compared with the existing test equipment, the invention can finish tests of automobile total mass, axle loads, wheel loads, centroid positions, anti-tipping angles and the like, so that the test workload and the test cost of the parameter tests are greatly reduced.

The invention discloses a multi-disciplinary optimization design method for the airfoil profile of a wind turbine. According to performance requirements for blade enlargement and operating environment diversification of the wind turbine, aerodynamic performance, structure attributes and acoustic characteristics of the airfoil profile are optimized at the same time, various performance requirements of the airfoil profile are parameterized, a multi-disciplinary optimal objection function of the airfoil profile is established in combination with a weight coefficient method, and an optimization design system of the airfoil profile of the wind turbine is established in combination with an optimization algorithm. Numerical prediction indicates that multiple aspects of aerodynamic efficiency, off-design point performance, variable working condition stability and the structure of the novel airfoil profile designed according to the multi-disciplinary optimization design method for the airfoil profile of the wind turbine are promoted under the condition that the aerodynamic sound pressure level is not increased obviously, meanwhile, the working range of the airfoil profile is optimized, and the airfoil profile has low stalling characteristic parameters and performance stability parameters.

The invention discloses a stability parameter test board for an automobile and belongs to the technical field of measurement. The test board is used for integrally testing a quality parameter, a mass center position parameter and an anti-rollover angle parameter of the automobile. The stability parameter test board consists of a measuring table board, four platform scales, a table board pillar, a foundation, three hydraulic cylinders, an inclination angle measuring device, hydraulic sensors, a pumping station and a computer, wherein the platform scales are arranged on the measuring table board and supported by a weighing sensor; supporting points of the table board pillar are distributed in a form of rectangular top points; the foundation is used for supporting the pillar and the table board; the three hydraulic cylinders are arranged between the table board and the foundation and can make the table board incline longitudinally or laterally; the inclination angle measuring device is fixed on the table board; the hydraulic sensors are arranged at upper and lower cavity positions of two hydraulic cylinders which make the table board incline longitudinally; the pumping station is connected with the hydraulic cylinders; and the computer is used for acquiring data of the weighing sensor, oil pressures of the hydraulic cylinders and the inclination angle of the table board and performing an operation. The table board has the advantage that: compared with a conventional test device, the device can complete tests on the total mass, the axle load, the wheel load, the mass center position, the anti-overturn angle and the like of the automobile, so the test workload and the test cost of the parameter test are lowered.

Disclosed herein is a method of estimating sediment content of a hydroprocessed hydrocarbon-containing feedstock. The method involves the steps of: (a) precipitating an amount of asphaltenes from a liquid sample of a first hydroprocessed hydrocarbon-containing feedstock having solvated asphaltenes therein with one or more first solvents in a column; (b) determining one or more solubility characteristics of the precipitated asphaltenes; (c) analyzing the one or more solubility characteristics of the precipitated asphaltenes; (d) determining asphaltene content of the liquid sample from the results of analyzing the one or more solubility characteristics of the precipitated asphaltenes; (e) determining one or more asphaltene stability parameters of the liquid sample from the results of analyzing the one or more solubility characteristics of the precipitated asphaltenes; and (f) correlating the asphaltene content and one of the asphaltene stability parameters of the liquid sample to estimate sediment content of the liquid sample.

The invention discloses a pump storage unit operation stability deterioration early warning method and a pump storage unit operation stable state deterioration early warning system. The pump storage unit operation stable state deterioration early warning method comprises the steps that stability real-time monitoring of a pump storage unit is carried out to acquire a monitoring value of a stability parameter; according to the working condition parameter of the pump storage unit, an upper limit value and a lower limit value, which are corresponding to a current working condition and a currently-compared stability parameter, are searched in a pre-established numerical early warning model; when the monitoring value is greater than or equal to the lower limit value, and is smaller than or equal to the upper limit value, the stability state of the pump storage unit is determined to be normal, and the monitoring value is stored in a normal state record library; when the monitoring value is smaller than the lower limit value or greater than the upper limit value, early warning information is output, and the monitoring value is stored in an abnormal state record library. By additionally providing the working condition parameter, and the pre-established early warning model is used to provide different alarming limit values for the different working conditions of the pump storage unit, and therefore the effective early warning in different working conditions is realized, the stability problem of the pump storage unit is discovered timely, and the precision of the early warning is improved.

The invention discloses a simulation method for detecting the side direction stability of a directly paved submarine pipeline and a simulation device; the invention firstly prepares a soil sample to simulate a seabed, mounts a test pipeline, releases the pipeline to lead the pipeline to generate initial sedimentation under the action of self-gravity when the pipeline is just contacted with the seabed and simultaneously adopts a laser displacement sensor to measure the initial sedimentation amount of the pipeline in a soil body, applies an incline pull to the pipeline through a stepping motor to simulate the actions of a horizontal daggling force and a vertical lifting force of a sea flow to the pipeline, and simultaneously measures the pull of the stepping motor, a horizontal displacement and an additive sedimentation amount during the side direction destabilization process of the pipeline, a displacement field of the soil body at the lower side during the side direction destabilization process of the pipeline, and a soil pressure of the side direction. The utilization of the simulation method and the simulation device of the invention can effectively simulate a bearing soil body, the horizontal dragging force and the vertical lifting force of the single-direction sea flow to the pipeline, etc., of the directly paved submarine pipeline and can monitor the stability parameters like the limit side direction soil resistance of a pipeline foundation in real time, thus being capable of simulating the side stability of the directly paved submarine pipeline.

A method, apparatus and program product may determine load stability for a load to be wrapped based upon sensing the response or reaction of the load to a disturbance applied to the load, e.g., through intentionally moving, shaking, tilting, pushing, impacting or otherwise applying an input force to the load and sensing the response using one or more sensors. The sensed response may then be used to determine a load stability parameter that may be used in the control of a load wrapping apparatus when wrapping the load.

A method of controlling an AC machine that includes a stator and a rotor. The method includes observing a stability parameter that is indicative of the stability of the AC machine and dependent on a current state of the AC machine; and controlling the AC machine based on the observed stability parameter so as to promote stable operation of the AC machine. The method may include controlling the AC machine to operate as a motor or as a generator. The AC machine may be a permanent magnet synchronous machine. A controller suitable for performing the method is also disclosed.

The embodiment of the invention discloses a coding method for voice frequency signals, which includes the steps of: obtaining the stability parameter of a current frame voice frequency signal and extracting time domain envelope information with the corresponding number from the current frame voice frequency signal according to the stability parameter of the signal; carrying out quantization coding on the extracted time domain envelope information and obtaining the coding code word of the time domain envelope; obtaining the quantization value of the time domain envelope information and utilizing the quantization value to carry out normalization processing on the current frame voice frequency signal; and carrying out transformation coding on the current frame voice frequency signal after normalization processing and a previous frame voice frequency signal. Besides, the invention also discloses a decoding method for voice frequency signals and a coding and decoding device. While getting rid of noise leakage problem caused by a transient signal, the invention also saves the resource of coding and decoding.

The invention provides an apparatus for measuring three-degree-of-freedom dynamic stability parameters of an aircraft in a high-speed wind tunnel. A pitching exciting piezoelectric ceramic vibration exciter is arranged in a support sting, one end of the vibration exciter is connected with the support sting, the other end is connected with a frame in parallel and is then connected with the rear end of a first connecting rod in a hinged manner, the central part of the first connecting rod is supported on the support sting through an elastic hinge, the front end of the first connecting rod is connected with a vibration cylinder in a hinged manner, an inner cavity of the vibration cylinder is provided with a T-shaped support rod, two ends of a vertical shaft of the T-shaped support rod are connected with the vibration cylinder in a hinged manner, two ends of a horizontal shaft of the T-shaped support rod is connected with a cylindrical balance in a hinged manner, a first yawing / rolling piezoelectric ceramic vibration exciter and a second yawing / rolling piezoelectric ceramic vibration exciter are arranged in the cylindrical balance, one ends of the first yawing / rolling piezoelectric ceramic vibration exciter and the second yawing / rolling piezoelectric ceramic vibration exciter are fixed to the vibration cylinder, and the other ends are connected with a corresponding second connecting rod in a hinged manner. The apparatus is arranged in the wind tunnel, and can accurately measure the three-degree-of-freedom dynamic stability parameters of the aircraft in the high-speed wind tunnel.

The invention discloses a method for parameter testing the performance of a wing profile special for a horizontal axis wind turbine. The method comprises the following steps of: firstly, acquiring the wing profile and aerodynamic data thereof; secondly, analyzing the geometry parameter of the wing profile and dividing the wing profile into a thin type and a thick type according to different relative thicknesses; thirdly, obtaining a design point performance parameter item, a non-design point performance parameter item, a stalling characteristic parameter item and a stability parameter item of the wing profile; fourthly, comparing with the performance reference index of the wing profile to obtain a relative value and judging the performance level of the wing profile; and finally, endowing the wing profile with different weight coefficients according to different types of the wing profiles, and calculating an overall performance evaluation value of the wing profile based on the relative value to judge the performance level of the wing profile of the wind turbine. The invention can provide a judging basis and a method for selecting different wing profiles on different parts when wind turbine blades are designed or can be used for evaluating the performance of an intermediate wing profile during design and optimization of new wing profiles.

The invention discloses an electro-osmosis consolidation shearing device. The electro-osmosis consolidation shearing device comprises a frame, a vertical loading system, a horizontal shearing loading system and an electric insulation experiment box, wherein the frame comprises a bottom frame and a portal frame; the bottom frame is fixedly connected with the portal frame; the vertical loading system is fixedly connected to the upper wall of the portal frame, and comprises a shaft pressure air cylinder, a shaft pressure displacement electronic sensor and a shaft force sensor; the electric insulation experiment box comprises electrode tubes, an upper shearing box and a lower shearing box; during an electro-osmosis experiment, soil is placed in the upper shearing box and the lower shearing box, and the electrode tubes are inserted into the soil. The electro-osmosis consolidation shearing device is high in experiment efficiency, small in occupation area, convenient to operate, compact in structure, accurate and reliable in determination result, and applicable to an indoor or field experiment for the electro-osmosis test on soft clay and mucky soil in eastern coastal regions and the Pearl River Delta region, and serves for solving the related engineering problems of foundation deformation and stability parameter determination in geotechnical engineering problems of foundation treatment, coastal reclamation, port revetment and the like.

The invention provides a trace metal element chelation fertilizer in lignin and application thereof. The trace metal element chelation fertilizer in the lignin is a mixture of lignosulfonate and metal element chelates and shows the following physical-chemical characteristics of: 1, appearance: white powder; and 2, stability parameters of chelate: the average coordination number x is between 0.9 and 1.95 and the stability constant 1gK is between 0.6 and 2.10; and 3, the metallic chelation rate is 10 to 13.55 percent. The lignosulfonate-metal element chelation fertilizer is prepared by performing oxidative modification reaction on paper-making waste liquid lignosulfonate and metal elements such as iron, zinc and copper which serve as raw materials, and the chelation property of lignin ammonium is quantitatively described by measuring the stability of the chelates of lignin ammonium-Fe and lignin ammonium-Zn. The industrial lignin and the metal elements form the 'lignin-metal elements' chelates, and the obtained chelates are dried to form solid products or the obtained chelates after proper concentration can be mixed with other kinds of fertilizers to prepare various compound fertilizers.

The invention discloses the method for picking-up and monitoring the character of on-line stability of the half speed whirl for the on-the-fly machine. The electric whirl displacement sensor of non-contacted type obtains the vibration displacement signal of the rotator. The vibration displacement signal is preprocessed through the FIR filter technique so as to reserve the component near the half-frequency and filter out other interference component. Then, the RDT techniques pick-up the stability parameter of the system is obtained through the genetic algorithm. The trend map between the stability parameter and time can be drawn out.

The invention discloses an online identification method of small-disturbance stability parameters based on PMU measurement data. The method includes: according to a linearization state matrix, with the combination of the PMU measurement data (generator angular velocity, power angle and internal potential trend data) of an electric power system, the matrix operation form of the ordinary least squares solution of to-be-estimated parameters (conductance, susceptance, and generator time constant and damping coefficient) is deduced. The beneficial effects of the method are that the current operation state can be accurately reflected through abundant measurement data, and a great help is provided for the improvement of the accuracy of practical parameters of the electric power system.

The invention discloses a stability measurement and calculation method for a viscous debris flow entity silt arrester, and aiming at avoiding the defect that a conventional measurement and calculation method only draws the most extreme situations into consideration and cannot demonstrate the dynamic change process of the stability of the silt arrester in the debris flow process, provides the stability measurement and calculation method which can reflect the dynamic change process of the stability of the silt arrester in the process that the entity silt arrester intercepts debris flow. The stability measurement and calculation method comprises the following steps: firstly, investigating and determining that the entity silt arrester belongs to an empty reservoir overflowing working condition or a half reservoir overflowing working condition; determining engineering parameters through field investigation, indoor soil tests and silt arrester design projects; and measuring and calculating the stability of the silt arrester by use of calculation methods of anti-slip stability parameters Kc(n-1) and stability against overturning parameters Ky(n-1) under different working conditions. The stability measurement and calculation method can be used for particularly measuring and calculating the stability of the silt arrester in the full reservoir overflowing state, can provide scientific basis and references for parameter optimal design, structural safety checkup and the like of debris flow control projects, avoids waste of the construction cost, is closer to the project reality and conforms to the requirements of actual engineering.

The invention relates to 3 mu m luminous rare earth ion doped fluorophosphates laser glass and a preparation method thereof. The glass comprises the following components by molar percent: 15-20% of Al(PO3)3, 13-17% of MgF2, 5-25% of CaF2, 5-25% of SrF2, 17-22% of BaF2, 18-22% of NaF and 3-5% of RF3 (R can be rare-earth elements such as Er, Pr, Tm, Ho, or Nd). The glass is prepared by using a platinum crucible and a silicon carbide rod electric furnace fusion method. The glass in the invention is transparent, has no crystallization, has high infrared transmissivity at the vicinity of 3 mu m wave band, good physical and chemical properties and stability parameter delta T of more than or equal to 150 DEG C and can obtain strong 3 mu m fluorescence under the pumping of a laser diode with a wavelength of 980 nm, and the method is suitable for preparation and application of 3 mu m luminous rare earth ion doped special glass and optical fiber materials.

The invention discloses a method for designing stability parameters of a self-adapting filter of a self-balancing system of a magnetic suspension rotor. The method comprises the following steps of establishing a radial rotation dynamics differential equation model of the self-balancing system of the magnetic suspension rotor with a gyroscopic effect; converting a real coefficient bivariate gyroscopic coupling system into a complex coefficient univariate equivalent system through complex transformation; calculating a closed-loop transfer function of the complex coefficient univariate equivalent system; determining a start angle range of a root locus, which meets the stability requirement of the self-balancing system, at a critical stable point of an imaginary axis; resolving a stability parameter intersection of the self-adapting filter; finally, determining the stability parameters of the self-adapting filter. While the rotor speed is estimated and tracked in real time so as to improve the self-balancing precision, the stability of the self-balancing system of the magnetic suspension rotor with the gyroscopic effect within a full speed range is ensured. The method disclosed by the invention is simpler and more convenient than other methods, and is especially suitable for practical magnetic suspension rotor systems.

The invention discloses a double-air-spring comprehensive performance test bench, belonging to the technical field of vehicle engineering. The dynamics problems of key components which are a height valve, a pressure valve and an anti-rolling torsion bar in an air spring in the process of vehicle running can be effectively simulated. The double-air-spring comprehensive performance test bench comprises a multi-direction actuator working table, an additional air chamber, an air inflation and exhaustion system and counterweights, and an upper end counterweight only limits longitudinal motion. Multi-dimensional and multiphase excitations are applied to double air springs, under the different temperature conditions, the load, deflection change, and vehicle lateral and vertical acceleration and displacements of the air springs under different physical parameter conditions are measured, the dynamical parameters of the air spring such as every direction dynamic rigidity, a damping ratio, a displacement transfer ratio and an acceleration transfer ratio are calculated according to vibration performance parameters, two-point control and four-point control are compared, thus an air spring dynamics performance test is completed, and the operation stability parameters of the vehicle is obtained. The double-air-spring comprehensive performance test bench is mainly used for a double-air-spring comprehensive performance test.

The invention provides a unit speed regulation system control parameter setting method considering frequency modulation and stability constraints. The method comprises the following steps: S1) carrying out analysis on stability of a possible isolated-network-operation hydropower unit speed regulation control system; S2) obtaining a range of control parameters with primary frequency modulation performance constraint of a unit being taken into consideration; S3) under the premise of meeting small disturbance stability, giving a range of control parameters of the unit speed regulation system; S4) obtaining unit prime motor and speed regulation system measured parameters through actual measurement modeling, and obtaining overlap based on the ranges of the control parameters and applying the data to simulation analysis verification instances of the setting method; and S5) for a primary frequency modulation parameter setting range and a small interference stability parameter stability range, carrying out overall consideration, and finally, obtaining a parameter value range capable of meeting both frequency modulation performance requirements and small interference stability requirements, and carrying out setting on the unit speed regulation system model parameters. The method can obtain parameter values meeting both requirements under the premise of meeting double-term index requirements.

The invention discloses a hydroelectric generating set starting process stability state evaluation method. The method comprises the steps of S1 obtaining the health samples of hydroelectric generatingsets working at different water heads in the normal starting process, wherein the health samples comprise working condition parameter data and N types of stability parameter data; S2 dividing workingwater head intervals of the hydroelectric generating set, and arranging health samples of the normal starting process of the hydroelectric generating set in each water head interval according to eachwater head interval; S3 extracting health samples in each water head interval, and drawing a stability parameter peak-to-peak health region corresponding to each type of stability parameters in eachwater head interval; and S4 monitoring the starting process of the hydroelectric generating set to be evaluated in real time, and calculating the overall stability state evaluation index of the starting process of the hydroelectric generating set to be evaluated. According to the method, the starting process of the hydroelectric generating set can be effectively monitored, and the stable state degree of the starting process of the set is quantitatively evaluated, so that the stable operation of the set is guaranteed, and the guidance suggestions are provided for stable operation of the starting process of the hydroelectric generating set.

The invention relates to a an electric arc welding method, wherein an electrode assembly (100) comprises at least two fusible continuous electrodes (110, 112, 114, 116, 118) acting on a workpiece (10) for generating a weld pool (12) via electric arcs, wherein the at least two electrodes (110, 112, 114, 116, 118) are arranged in sequential order relative to a welding direction (30) and laterally separated relative to each other, wherein steps are performed of monitoring at least one stability parameter (Stab_par) for each electrode (110, 112, 114, 116, 118) of the electrode assembly (100); determining if one electrode (116) of the electrode assembly (100) violates a stability criterion (Crit); separating at least temporarily the one electrode (116) violating the stability criterion (Crit) from one or more adjacent electrodes (110, 112, 114, 118) when a violation of the stability criterion (Crit) of the one electrode (116) is detected.

This thick steel sheet contains prescribed steel components, the Di value composed of the steel components is 2.5 or greater, the residual austenite phase (residual (γ)) remaining at -196°C is 2.0 to 12.0% by volume fraction, and the residual (γ) stability parameter composed of the components contained in the residual austenite at -196°C satisfies the condition of 3.1 or greater.

The invention discloses an application program test method and device. The method comprises the following steps of: operating a target application program, wherein the target application program is ato-be-tested application program, a target code is injected in the target application program, and a target application process is generated in a process of operating the target application program; monitoring operation data of the target application process, wherein the operation data comprises normal exit data and abnormal exit data of the target application process; determining a stability parameter of the target application process according to the normal exit data and the abnormal exit data; judging whether the stability parameter satisfies a preset condition or not; and under the condition that the stability parameter does not satisfy the preset condition, deleting the target code from the target application program. According to the method and device, the technical problem that thetest of application programs is low in correctness in the prior art is solved.

The invention discloses a shallow-buried close-range room and pillar type goaf uplink mining rock stratum stability analysis method, which is characterized by comprising the following steps of: 1, constructing a box girder bridge model; Step 2, determining basic parameters of the box girder; and 3, analyzing the stability of the box girder bridge according to the structural characteristics of thebox girder bridge, wherein the analysis comprises discrimination of the stability of a structural web of the box girder bridge and discrimination of the stability of a room column. According to an existing mechanical theory and a mine pressure theory, the shallow-buried close-range room column type goaf uplink mining system is subjected to mechanical analysis and research according to the box girder bridge structure model, and scientificity, practicability and rationality of determination of stability parameters of the shallow-buried close-range room column type goaf uplink mining system are ensured.

The invention relates to 2 mu m fluo-phosphate laser glass with a low-phosphorous content and a preparation method thereof. The glass has the composition by molar percentages as following: 3 to 6 molar percentages of Al(PO3)3, 30 to 35 molar percentages of AlF3, 9 to 12 molar percentages of MgF2, 14 to 18 molar percentages of CaF2, 5 to 8 molar percentages of SrF2, 9 to 14 molar percentages of BaF2, 8 to 11 molar percentages of NaF, 0 to 6 molar percentages of LaF3, and 4 to 10 molar percentages of RF3, wherein R is rare earth elements, such as Yb, Er, Tm and Ho. A melting method is used for preparing the fluo-phosphate glass, and the prepared glass has good physical and chemical properties, the stability parameter delta T being more than or equal to 100 DEG C. Strong 2 mu m fluorescence can be obtained by a laser diode pump with the wave length of 980 nm or 800 nm. The invention is suitable for the preparation and the application of the 2 mu m luminous specific glass and the optical-fiber material which are mixed with rare earth ions.