248 results about "Water dynamics" patented technology

The stereo in-situ ecological urban water system repairing process tackles polluted water via the quantitative analysis on the water. The technological scheme includes physical simulation and mathematic model analysis, microbe inoculation and culture, constituting refluxing ecological filter bed, purification with biocarrier, artificial aeration, purifying upper water, pre-treatment in the blow down port, establishing water ecological system balance, perfecting water environment data, etc. The present invention realizes the comprehensive tackling of urban water system.

The invention relates to a method and system for establishing a multilayer oil pool inter-well connectivity model. The multilayer oil pool inter-well connectivity model capable of simulating oil and water dynamic states is established oriented to the limitation that by means of a current connectivity model, only the dynamic change of production liquid can be predicted, the dynamic states of the oil phase and the water phase cannot be calculated respectively, and connectivity analysis cannot be carried out layer by layer. According to the model, an oil pool system is layered and scattered into a series of inter-well communication units, matter balance equation calculation is carried out with the inter-well communication units as simulating objects, pressure solving and inter-well flow calculation are achieved, an inter-well saturation degree tracking calculating method is established with the combination of the lead edge boosting theory, and the output dynamic states of oil and water of all layers at well points are obtained; a model parameter inversion method is established in a fitting mode through dynamic states based on a random disturbance approximation method, a projection gradient method and the like. Layered inter-well flow distribution coefficients, single well longitudinal production liquid and production oil splitting coefficients and other information can be obtained in real time, the oil pool plane, the longitudinal oil and water flow relation and the production measure change can be more accurately reflected to guide the practical production of an oil field.

The invention provides a decision-making method for soil moisture monitoring and intelligent irrigation of the root zone of crop. The method comprises three steps of (1) acquiring soil moisture data by using soil moisture sensors based on the theory of time domain reflection or frequency domain reflection; (2) establishing a soil moisture mathematical model by adopting the numerical simulation method based on a dynamic data driving application system to correct the soil moisture value; and (3) comparing the soil moisture value, obtained by a hydrodynamic model, of the root zone of crop with the set irrigation threshold value of crop, and making the irrigation data decision. According to the method, simulated forecast on soil moisture is made by taking the dynamic data driving application system as a technological paradigm, various updated actually measured meteorological data as basis, and actually measured initial soil moisture and real-time surface soil moisture state, growing state of crop and the like as base; therefore, the dynamic property and the real-time property of the soil moisture forecast are improved, which has great significance for making a water plan.

The invention discloses a construction method of a flat shoal flow prediction model based on joint control of upstream-downstream borders over a lower reach. The construction method specifically comprises the steps of adopting a one-dimensional hydrodynamic model to calculate and study a water level-flow relation curve of each fixed section in the reach; determining flat shoal flow in each section according to flat shoal elevation in each fixed section; adopting a method based on the combination of geometric average of logarithmic transformation and weighted average of section spacing to calculate the flat shoal flow of reach dimension; analyzing a response relationship of the flat shoal flow adjustment on an upstream water-sediment condition and downstream water level change, and constructing the prediction model based on joint control of the upstream-downstream borders over the lower reach. According to the construction method of the flat shoal flow prediction model based on joint control of the upstream-downstream borders over the lower reach, the calculated and obtained flat shoal flow of reach dimension is capable of better describing the flow passing capacity of the whole reach, and thus the flat shoal flow is more representative; the constructed flat shoal flow prediction model is capable of well reflecting the variation trend of the flat shoal flow along with the upstream water-sediment condition when the downstream water level changes sharply, and thus the constructed flat shoal flow prediction model has a guidance significance in the flood prevention and riverway management.

The invention relates to the technical field of hydrodynamic experiment and search, and more specifically, relates to a nonlinear and multidirectional irregular wave and internal wave generating system and a control method therefor, wherein the system is used for generating high-precision nonlinear multidirectional irregular waves and internal waves in a pool. The system based on vertical multilayer and horizontal multi-plate control comprises a test pool (comprising a wave absorbing segment), a computer control drive system, a mechanical transmission system, a wave generating plate system (vertical multiple plates and horizontal multiple groups), and a wave height monitoring system. There are two fluid layers with different densities in the test pool during wave generating, or there is one fluid layer in the test pool otherwise. The system achieves the simulation of the nonlinear and multidirectional irregular waves and internal waves in the pool through the simultaneous control of a plurality of groups of horizontally arranged vertical multi-plate wave generating mechanisms and the different nonlinear vertical speed distribution of the two fluid layers or the single fluid layer, is higher in accuracy and precision, and meets the requirements of different tests.

A measuring device of fluid frictional resistance on flat plate wall surface is prepared as connecting buffer water tank to water pool and to water flow pipe separately; connecting water flow pipe to water pool through elbow; forming water flow pipe by reducing section, developing section and testing section with rectangular cross ¿C section; placing flat plate to be measured in testing section and using flat plate as plate wall of testing section for carrying out frictional resistance test on wall surface.

The present invention relates to a deep water flow flow-rate measuring system. Said system includes the following several portions: a mobile device, a fixing frame, a computer, an A / D conversion card, a D / A conversion card, an ac servo-driver, an ac motor, a coder, a speed reducer, a vertical lifting device and a probe. Said invention also provides the concrete action of the above-mentioned every portion and concrete connection relationship of all the above-mentioned portions. Besides, said invention also provides the working principle of said system.

The invention discloses a cascaded multi-ditch gate lockage discharge coefficient calibration method, and relates to the field of hydrodynamic parameter identification. The method comprises the steps of building a hydrodynamic simulating and forecasting model of a researching channel section; combining flow measured values and water level measured values of all gates in the researching channel section, and using a Kalman filtering assimilation algorithm to obtain a real-time analysis water level sequence; utilizing a Saint-Venant equation to deduce and obtain an analysis flow sequence of a ditch gamma according to the real-time analysis water level sequence of the gates of any ditch gamma in the researching channel section; deducing and obtaining a ditch gamma lockage discharge coefficient by utilizing the real-time analysis water level sequence of the gates of the ditch gamma and the analysis flow sequence of the ditch gamma. By means of the cascaded multi-ditch gate lockage discharge coefficient calibration method, the precision of the hydrodynamic simulating and forecasting model is sharply improved, and the accuracy of a forecasting value is improved.

The invention belongs to the technical field of hydrological water resources, and discloses a water resource simulation method based on SWMM and MODFLOW coupling, which comprises the following steps:collecting research area space geographic data, meteorological data, rainfall-related hydrological data and hydrogeological basic data; constructing an SWMM and MODFLOW coupling model suitable for theresearch area in combination with the collected data; constructing different rainfall scenarios, and analyzing the dynamic change of the surface water under the different rainfall scenarios in combination with the SWMM model; different rainfall supply scenes are constructed in combination with an SWMM model simulation result, and underground water dynamic changes under the situation that different rainfall is not given are analyzed in combination with an MODFLOW model. According to the coupled water resource simulation method provided by the invention, the problems of local waterlogging, serious river water quality pollution, water body ecological environment deterioration and other urban rainwater in a traditional water treatment mode of a quick drainage mode in an extreme weather in a region with higher urbanization are effectively avoided, and the drainage intensity of a city is improved.

The invention provides a three-dimensional simulation device for coal seam group mining and water dynamic seepage in the roof and goaf, including a test bench, a rock-soil layer for testing, a mobile observation device for the ground surface, and a water source supply for the aquifer of the rock-soil layer For the device, the upper coal seam and the lower coal seam of the rock and soil layer used for the test are replaced by a hydraulic pillow structure and / or a jacking jack structure, and the hydraulic pillow structure realizes the mining of the simulated coal seam through a side pulling power device arranged outside the test bench. The present invention is provided with a hydraulic pillow structure replacing the upper layer coal and mining and a lifting jack structure replacing the lowermost layer coal and mining in the test frame, which can accurately grasp the direction and tendency of the upper layer coal and the lower layer coal after mining. The law of supporting pressure distribution; The water replenishment structure provides the required amount of water for the aquifer, so that the coal mining and the continuous water supply of the aquifer can be carried out simultaneously, and the effects of effectively simulating the three-dimensional roof dynamic movement damage and fracture seepage of multi-coal seam mining in the area can be realized.

A periodical injection-production method of water-injected sandstone oil field utilizes well area selection, periodical water injection mode, and water interval injection period, water injection ratio recovery to form an optimized technical scheme for saving the amount of water injection and for controlling decreasing amplitude of production output.

The invention relates to the technical field of hydrodynamic experimental researches, in particular to a vertical multi-plate wave maker. The vertical multi-plate wave maker comprises a water tank, a hydraulic station, a computer control system, a support, an actuator and a wave-making plate, wherein the hydraulic station is arranged on the water tank; the computer control system is used for generating nolinear wave control signals; the actuator is connected with the support; the wave-making plate is hinged with the actuator; the computer control system is electrically connected with the hydraulic station; the hydraulic station is connected with an actuator; the actuator is used for driving the wave-making plate to perform reciprocating motion; and the wave-making plate is formed by hinging a plurality of independent wave-making plates. According to the vertical multi-plate wave maker, vertical speed distribution can be accurately input, waves which are more complex and more variable than those produced by a vertical single-plate wave maker can be produced, and the wave-making accuracy is improved; an embedded system, a programmable logic controller or an industrial personal computer can be selected as a computer control unit, and the quantity and the size of required split plates are selected according to different application requirements of control accuracy, response speed, stability and the like; and on the premise that high accuracy and high response speed are guaranteed, the flexibility and the stability of system operation are enhanced, and the repairing and maintenance costs are reduced.

The invention discloses a ship sailing aiding and formation commanding method. When a destination and formation type is determined, a flagship plans ships to arriving set positions at set time; each ship treat a water dynamic system as a black box to invert resultant force stressed by the ship along the set sailing trajectory, sailing trajectory of each ship at the next time period is predicted according to current real-time sailing parameters and historical sailing state parameters of the ship, the predicted sailing trajectories, the planned sailing curves and real-time sailing curves are drawn together on a real-time sailing interface map, and the ships are controlled to sail along the predicted sailing trajectories; and real-time positions and real-time sailing parameters of the ships are monitored and used as the historical sailing parameters to feed back to be used for predicting sailing trajectories of the ships, and the real-time saving parameters are drawn into operation vectors tangent to the predicted sailing curves. The ship sailing aiding and formation commanding method uses a distributed control system, is flexible to control, convenient to operate, and has high fault tolerance and extensibility.

A submarine with duck-type layout features that its floatage is close to and slightly greater than its gravitation to make the central point of floatage action is above its gravitational center, and 4 linked elevating rudders are arranged at both sides of submarine to make their total vertical action line coincides with the gravitation line of submarine. A method for controlling its navigation depth features used of a closed-loop negative feedback control system to control the deflection angle of 4 elevating rudders. A method for suspending it at a given position in seawater features use of at least two closed-loop negative feedback control systems for the distance and depth control to regulate the direction and speed of propeller and the deflection angle of elevating rudders. It is more suitable for robot submarine or toy.

The invention provides an object-oriented hydrodynamic modeling element management method. The method comprises the steps of obtaining multi-class basic data of hydrodynamic modeling, and building an object-oriented model element of flood analysis modeling according to the multi-class basic data, wherein the object-oriented model element comprises a one-dimensional river network model element, a two-dimensional shallow water model element and a city pipe network model element, the one-dimensional river network model element comprises one-dimensional river network data and a hydrology sequence, the two-dimensional shallow water model element comprises two-dimensional grid data and a time sequence, and the city pipe network model element comprises a subsidiary catchment area, a pipe section, a node, a hydrology station network, a curve set, a time mode and LID control; providing creating, deleting, drawing and importing functions for each model element. According to the object-oriented hydrodynamic modeling element management method, by obtaining basic data related to flood, a one-dimensional city pipe network, a two-dimensional city pipe network, a one-two dimension-coupled city pipe network and a pipe network two-dimensional model element are built, so that a flood analysis model which is suitable for country pipe networks and city pipe networks is conveniently put up, and the flood analysis model is suitable for subsequent flood analysis of different areas.

The present invention discloses a heat energy recycling device for an engine and a two-stroke engine using the same, which recycles the heat energy of the exhaust gas of a two-stroke engine and uses a technology of directly injecting high-pressure and high-temperature water into the cylinder. At an appropriate timing, fuel supply is intermitted, and high-pressure and high-temperature water is injected into the cylinder before or at the beginning of the explosion stroke. The high-pressure and high-temperature water vaporizes instantly inside the cylinder because the saturation temperature at the pressure is much lower than the temperature of the water. The water vapor pushes the piston to move and generates a water dynamic stroke. During the water dynamic stroke, the gas inside the cylinder expands, and the temperature thereof decreases. Thus, the gas inside the cylinder has a temperature lower than that of the cylinder and absorbs heat from the cylinder wall. Then, more heat of the cylinder is recycled, and the urgency of installing a heat-dissipation system is decreased. The present invention recycles heat energy from waste gas and the heat-dissipation system to generate dynamic power and realizes a low-fuel consumption and high-compression ratio two-stroke engine.

The invention relates to a dynamic visualization observing device for a displacement experiment. The dynamic visualization observing device comprises a fluid pumping-in device, a middle piston container I, a middle piston container II, a rock core slice, a fluid collecting container, a dynamic visualization micro model and an observing assembly. The middle piston container I and the middle piston container II are connected in parallel between the fluid pumping-in device and the rock core slice, and the rock core slice is arranged inside the dynamic visualization micro model. The dynamic visualization micro model is prepared from polydimethysiloxane, an oil and water injection opening and a liquid discharging opening are formed in the parts, with the equal distance to the center, on the two sides of the center of an upper model body respectively, the rock core slice is embedded in the center of a lower model body in a pressing mode, and thus a groove with the shape and dimension the same with those of the rock core slice is formed. The device is simple in structure and convenient to operate; the rock core slice is fixed by heating and softening the lower model body, the oil and water dynamic moving rules and distribution situations of different reservoir types are observed through different rock core slices, and then schemes for exploiting oil pools and increasing the oil recovery are made in a targeted mode.

The invention discloses a working ROV (Remotely Operated Vehicle) training simulator motion control simulation system, comprising an ROV body hydrodynamic system model, a seabed flow field disturbance speed model, a manipulator working disturbing force and moment model, an umbilical disturbing force and moment model, an ROV six-degree-of-freedom PID controller module, an overdriven thrust distribution module, a hydraulic airscrew propeller simulation control module, an eight-propeller thrust and moment model for thrust synthesizing six degrees of freedom, a six-degree-of-freedom thrust and moment and external disturbing force and moment synthesis module, an ROV automatic control function module and a four-degree-of-freedom ROV operation handle module. The system has the characteristics of simple structures and clear levels, and can truly describe the internal control system structure of a working ROV, accurately stimulate the real underwater motion control function and process of the working ROV, and realistically output motion and control parameter change processes of the working ROV.

The invention discloses a shallow lake group water quality, water quantity and water ecological coupling scheduling analysis method. The method comprises the following steps of 1) collecting researcharea data; 2) establishing a shallow lake group hydrodynamic model; 3) constructing a shallow lake group water quality model; 4) coupling of a hydrodynamic water quality model; 5) constructing a shallow lake group water ecological model; 6) constructing a shallow lake group hydrodynamic water quality and water ecological coupling model; 7) carrying out the parameter calibration of the model; 8) scheduling and analyzing. According to the analysis method, the regional water environment treatment scheme of water quality, water quantity and water ecological coupling dispatching is considered fromthe perspective of the whole lake group, the shallow lake group is dispatched, and the self-cleaning capacity of lake group water bodies can be utilized to reduce the pollutant concentration of a heavy pollution region to the maximum extent.

The invention relates to a simulation experimental method of a pollution source of the earth surface and the water-bearing stratum based on an underground water dynamic simulation experimental platform. The method particularly comprises the following steps: firstly, arranging the underground water dynamic simulation experimental platform; then filling the underground water dynamic simulation experimental platform with an aeration zone and a water-bearing stratum medium for simulating a typical hydrogeological unit; and finally carrying out an underground water level simulation experiment on the underground water dynamic simulation experimental platform. According to the method, different reagents can enter the aeration zone and the water-bearing stratum medium in a box type shell by multiple modes, and powdered reagents are added by virtue of a raining simulation device, so that the process that how the reagents penetrate the aeration zone from the earth surface and enter the water-bearing stratum and how the reagents are migrated and transformed in the water-bearing stratum can be observed. By adopting the method, the fidelity of simulation experiments can be improved, the cost of simulation experiments can be reduced, and a reliable experiment foundation is provided for an in-situ chemical oxidation technology, an in-situ biological repairing technology, a permeable reactive barrier process, a soil in-situ leaching remediation process and other research experiment projects.

The invention relates to the field of coal exploitation, in particular to a prevention and treatment method for coal seam roof separation water. According to the method, in the process of advancing of a work face of a coal seam, a plurality of ground straight-through type water draining holes are formed from the ground to the coal seam, and full-hole penetrating of the straight-through type water draining holes is completed before the work face advances to the position 50 m away from the ground straight-through type water draining holes; and upper openings of the ground straight-through type water draining holes communicate with the ground, and final hole positions should completely exceed a fissure zone and extend to a caving zone, so that the separation water can be drained effectively. Surging disasters of the accumulated separation water can be effectively prevented, intra-hole overlying stratum deformation dynamic observation, fissure zone searching, underground water dynamic monitoring and the like can be carried out, the problem of the accumulated separation water is solved, the capacity of water draining equipment is guaranteed, and an emergency working function is achieved.

The invention provides a pollution risk evaluation method for an underground water type drinking water source region, wherein the pollution risk of the underground water type drinking water source region can be evaluated at a time aspect and a space aspect. The pollution risk evaluation method comprises the steps of acquiring an underground water inherent vulnerability evaluation result and a pollution source damage grade at an area with the underground water type drinking water source region; combining the underground water inherent vulnerability of the area with the pollution source damage grade, and performing preliminary evaluation on an area pollution risk; combining underground water dynamic change information with an exploitation condition on a preliminary evaluation result, thereby obtaining a water resource region pollution risk evaluation on the exploitation condition; based on the water resource region pollution risk evaluation result on the exploitation condition, combining underground water value information for performing secondary evaluation on the area pollution risk; and performing migration simulation on characteristic pollutants on the exploitation condition of the water source region based on the secondary evaluation result, thereby finishing pollution risk evaluation on the underground water type drinking water source region. The pollution risk evaluation method is suitable for the technical field of environmental science and environment risk.

The invention relates to a treatment method for determining the position of a landslide drainage water line simultaneously on the basis of the underground water level and displacement monitoring data and coupling analysis. The method for determining the side slope critical drainage water line on the basis of monitoring comprises a first step of landslide monitoring section and monitoring point selection and determination, a second step of installation and arrangement of landslide underground water level and displacement monitoring devices, a third step of real-time monitoring and treatment of the underground water level and displacement, a fourth step of determination of the landslide underground water dynamic increment displacement response rate, a fifth step of determination of a landslide underground water dynamic increment displacement response ratio and a time sequence curve of the landslide underground water dynamic increment displacement response ratio and a sixth step of determination of the landslide critical underground water drainage water line. The landslide drainage water line is obtained by utilizing underground water dynamic increment displacement response ratio parameters so as to treat landslide with underground water serving as a leading trigger factor, the relations between the real landslide water line and a landslide stability state can be reflected visually, and effectiveness and practicality of the method are embodied.

The invention relates to a simulating and monitoring device for health status of a wetland water ecological system, which is characterized by comprising a wetland environment information collection and adjustment and control device, a wetland ecological system simulating device, a wetland water dynamic environment simulating device and a water ecological health monitoring device, wherein the wetland environment information collection and adjustment and control device comprises a greenhouse, the peripheral wall of the greenhouse is provided with a greenhouse inlet, a fan and a side window, a skylight, a fluorescent lamp, a temperature sensor and an illumination sensor are arranged on a ceiling, a heating device is arranged inside the greenhouse, and a control cabinet and a computer are arranged outside the greenhouse; the wetland ecological system simulating device comprises a planting trough arranged in the greenhouse, the planting trough is connected with a drainage pipe, and an automatic water makeup system is arranged at the outer side of the planting trough; the wetland water dynamic environment simulating device comprises an automatic lifting power device and a water flow propeller; and the water ecological health monitoring device comprises an automatic lifting power device and a biological membrane culture device. The two automatic lifting power devices respectively comprise a motor arranged on the ceiling of the greenhouse; the motors are connected with a suspension cable winding shaft through a gearbox; a suspension cable is wound on the suspension cable winding shaft, and the other end of the suspension cable droops and is connected with the water flow propeller or the biological membrane culture device.

The invention relates to a coupling method and system for a one-dimensional hydrodynamic model and a two-dimensional hydrodynamic model. The method comprises steps that the one-dimensional hydrodynamic model is constructed; wherein the one-dimensional hydrodynamic model comprises a one-dimensional river network water flow mathematical model; a two-dimensional hydrodynamic model is constructed to simulate two-dimensional shallow water flow of an earth surface; and according to the one-dimensional hydrodynamic model and the two-dimensional hydrodynamic model, a corresponding one-dimensional andtwo-dimensional hydrodynamic model coupling mode is carried out for various river section forms. According to the method, a one-dimensional and two-dimensional coupled hydrodynamic model is adopted, the influence of urban buildings, trees and other plants on flood propagation can be fully considered, and hydrodynamic models of different scales and different dimensions are coupled according to theone-dimensional flow characteristics of a river channel and the two-dimensional flow characteristics of a lake; and flood influence degree and range simulation and prediction under different flood frequencies are carried out. The urban water regime situation can be perceived, the water level information is collected in combination with an upstream sensing instrument, and the aims of reducing the discharge peak flow and achieving flood recycling are achieved in combination with gate dam dispatching.

The invention relates to the technical field of water conservancy research, in particular to a tree-shaped river network cascade reservoir hydrodynamic water quality and sediment coupling simulation method and system, and aims to solve the problem of integrity and reliability of river channel terrain sections and control line hydrological station data. After the cascade reservoirs are added, how to solve the problem of joint solution of the river network and the cascade reservoirs is solved, and a Western River midstream river network overall hydrodynamic simulation calculation platform integrating a cascade reservoir scheduling mode and a one-dimensional river network hydrodynamic model is established by relying on latest actually-measured water depth topographic data of the main and branch river channels. Model calculation is based on a one-dimensional Cherry View South Range. a calculation sequence for establishing a model from four levels of a river network, a sub-river network, ariver channel and nodes is provided. The river network and the cascade reservoirs are generalized. The river network and the cascade reservoirs are connected into a whole through the transmission relation of the water conservancy project scheduling mode and the external boundary conditions. All river segments are connected into a calculation whole, synchronous real-time simulation and calculationare achieved, and the research means of river network cascade reservoir scheduling is enriched.

The invention discloses a method for constructing an adjustment and prediction model for the low-flow channel morphology of an alluvial navigable channel. The method comprises the steps that S1, historical post-flood topographic data of all fixed sections of a channel segment and historical average-daily hydrologic data of (1) a trunk stream water level and a hydrologic station and (2) a branch stream water level and hydrologic station along the channel segment are collected; S2, based on the historical post-flood topographic data of all the fixed sections, a one-dimensional hydrodynamic model is adopted to calculate the water level flow relation curve of all the fixed sections; S3, according to the low-flow flow of the channel segment, through the water level flow relation curve of the fixed sections, the low-flow levels of all the fixed sections are determined, and low-flow channel morphology parameters of all the fixed sections are obtained according to the low-flow levels; S4, low-flow channel morphology parameters of the channel segment are calculated; and S5, the adjustment and prediction model for the low-flow channel morphology of the large-scale alluvial navigable channel is constructed. The adjustment tendency of the low-flow channel morphology of the large-scale alluvial navigable channel along with the flow-sediment condition can be well predicted, and the guiding significance is achieved for treatment of the low-flow channel.

The invention relates to a visualized test device for simulating the underground coalbed methane occurrence and desorption process. The device includes: a visualized simulation subsystem, a gas injection control subsystem, a constant pressure and constant speed pump, and a gas-water separation metering subsystem. The visualized simulation subsystem is used for visualized simulation of the gas-water dynamic change situation of the underground coalbed methane occurrence and desorption process, the gas injection control subsystem is used for supercharging or vacuum pumping of the injected gas ofthe visualized simulation subsystem, the constant pressure and constant speed pump is used for injecting water or extraneous liquid to the visualized simulation subsystem to construct an underground hydrodynamic field or extraneous engineering fluid affected environment, and a gas-water separation metering apparatus of the gas-water separation metering subsystem is used for separation metering ofgas-water mixed fluid discharged by the visualized simulation subsystem. The design environment provided by the invention comprehensively reflects the influence of the underground initial temperaturefield, hydrodynamic field, extraneous engineering fluid and the like on the underground coalbed methane occurrence and desorption law, and more truly reproduces the output change process of gas and water phases in the drainage and pressure reduction exploitation process of underground coal seams.