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125 results about "Rest frame" patented technology

In special relativity the rest frame of a particle is the coordinate system (frame of reference) in which the particle is at rest. The rest frame of compound objects (such as a fluid, or a solid made of many vibrating atoms) is taken to be the frame of reference in which the average momentum of the particles which make up the substance is zero (the particles may individually have momentum, but collectively have no net momentum). The rest frame of a container of gas, for example, would be the rest frame of the container itself, in which the gas molecules are not at rest, but are no more likely to be traveling in one direction than another. The rest frame of a river would be the frame of an unpowered boat, in which the mean velocity of the water is zero. This frame is also called the center-of-mass frame, or center-of-momentum frame.

Treadmill flat screen printing machine

The invention relates to the technical field of flat screen printing equipment and provides a treadmill flat screen printing machine. The treadmill flat screen printing machine comprises a treadmill frame, wherein running gears are arranged on the two sides of the treadmill frame; a treadmill station positioning device is arranged between the treadmill frame and two guide rails; a tool rest frame is arranged in the treadmill frame; a screen frame is rotationally arranged on the inner side of the tool rest frame; a screen frame positioning device is arranged between the screen frame and the guide rails; a scraper device driven by a scraper driving device is arranged on the tool rest frame in a sliding manner; lifting devices for driving the screen frame and the scraper device to rise or fall are arranged on the two sides of the treadmill frame respectively; the signal output terminal of the treadmill station positioning device is electrically connected with a signal processing unit; the signal output terminal of the signal processing unit is electrically connected with the signal input terminals of the running gears, the lifting devices and the scraper driving device respectively. According to the invention, effective and accurate walking and stopping movements can be realized when the treadmill flat screen printing machine walks between stations, and the screen frame can be accurately positioned on each station, so that the positioning accuracy of the treadmill flat screen printing machine is ensured.
Owner:王法聚

Deadbeat power control method for grid-side converter under network voltage unbalance

The invention belongs to the field of controlling power converters of wind power generation systems and relates to a deadbeat power control method for a grid-side converter under network voltage unbalance. The deadbeat power control method comprises the steps that three-phase network voltage, a three-phase alternating side current and direct current side voltage of the grid-side converter are detected, a network voltage sampling value and an alternating side current sampling value under a two-phase rest frame through 3/2 coordinate transformation, and network voltage retardation is obtained by delaying one fourth of a power grid period of the network voltage sampling value; an active power reference value is calculated, and an alternating side current reference value is calculated and obtained; transformer alternating current side voltage controlled by the deadbeat power is calculated; in order to compensate for time delay in the calculation and control process, the transformer alternating current side voltage at the next moment is predicted and serves as control voltage; a switch signal controlling a power switch component is obtained and is used for controlling on-off sequence and on-off time of the power switch component. According to the deadbeat power control method for the grid-side converter under network voltage unbalance, the grid-side converter can be effectively controlled to have good dynamic and static characteristics under the condition of network voltage unbalance, and reliable grid connection operation of a wind generating set is ensured.
Owner:TIANJIN UNIV

Fractional calculus-based PWM rectifier modeling method

InactiveCN105608266ATrue description of actual dynamic behaviorReflect the essential characteristicsSpecial data processing applicationsCapacitanceMathematical model
The invention discloses a fractional calculus-based PWM rectifier modeling method, and according to the method, a precise mathematic model of a single-phase PWM rectifier can be established on the basis of a fractional calculus theory and an instantaneous power theory defined by Caputo. The method comprises the following steps: firstly determining a voltage equation and a current equation of the single-phase PWM rectifier in a rest frame; defining and establishing a fractional order inductance equation and a fractional order capacitance equation of the single-phase PWM rectifier, and giving an input instantaneous power equation and an output instantaneous power equation of the single-phase PWM rectifier; and finally giving a direct-current component equation and an alternating-current component equation in an input instantaneous power and an output instantaneous power, and verifying the precision of the fractional calculus-based single-phase PWM rectifier fractional order model established on the basis of numerical simulation. According to the method, the fact that the capacitance and inductance are fractional orders in essence is considered in the modeling process, so that the modeling precision of the single-phase PWM rectifier.
Owner:HENAN POLYTECHNIC UNIV

Lower limb rehabilitation training elliptical machine device

The invention provides a lower limb rehabilitation training elliptical machine device which comprises a device rack, a driving transmission unit, an elliptical trajectory implementation unit and pedal plate connecting units, wherein the device rack comprises an arm-rest frame, a base and vertical plates; the driving transmission unit mainly comprises a drive motor, a small belt wheel, a big belt wheel and a synchronous belt; the elliptical trajectory implementation unit comprises a rotating disc, an elliptical sliding groove, a sliding block, a linear sliding rail and a group of guide wheels; the pedal plate connecting units comprise connecting pieces, pedal plates, flange plates and a bearing. According to the lower limb rehabilitation training elliptical machine device, provided by the invention, a patient is driven to be rehabilitated along the elliptical trajectory, which is more aligned with normal gait of people; besides, as the synchronous belt is in transmission connection with the linear guide rail, and the sliding block is matched with the elliptical sliding groove, the lower limbs can perform rehabilitation training along the elliptical trajectory, the machine device is compact in structure, the mechanism that forms the elliptical trajectory is driven in a single degree-of-freedom manner, and a better lower limb rehabilitation training effect is achieved.
Owner:HARBIN ENG UNIV

Four-wheel drive harvester for garlic

A four-wheel drive harvester for garlic comprises a rack, a power assembly is installed on the upper end face of the rack, and a front drive gearbox and a rear drive gearbox are installed in the middle of the rack. A front drive wheel and a rear drive wheel are installed on a power output shaft at the lower end of the front drive gearbox and a power output shaft at the lower end of the rear drive gearbox respectively. An eccentric wheel and a vibration frame are arranged at the rear end of the rack, wherein the eccentric wheel is connected with the vibration frame through a connecting rod. The two sides of the rear end of the vibration frame are respectively provided with a vibration shovel, and depth adjusting bolts are arranged at the connecting positions of handles of the vibration shovels and the vibration frame. An arm-rest frame support base is arranged between the upper side of the front drive gearbox and the upper side of the rear drive gearbox. An arm-rest frame is installed on the arm-rest frame support base, a height adjusting fluted disc is arranged at the connecting position, and a clutch handle and a throttle control handle are arranged on the arm-rest frame. The clutch handle is connected with a tensioning clutch device, and the throttle control handle is connected with the power assembly. Compared with the prior art, the four-wheel drive harvester has the advantages that the structure is compact, four-wheel drive is adopted, power is high, the drive wheels do not slip, operation is flexible, harvesting speed is high, harvesting efficiency is high, and the harvester is suitable for cultivated lands different in soil quality.
Owner:YISHUI SHUTUO MACHINERY

Processing technique for heavy crankshaft and shaft part milling frame stations and technique equipment

The invention discloses a processing technique for heavy crankshaft and shaft part milling frame stations and technique equipment, and belongs to the technical field of machinery manufacture. The processing technique equipment is separated from the supporting of a central frame and the processing of a large tonnage rough turning machine tool, a worm gear and a transmission gear are arranged in a rotating mechanism of the equipment, a motor drives the transmission gear in the rotating mechanism, and an apex is arranged on the inner sides of the rotating mechanism and a jacking mechanism respectively; a workpiece is arranged between the two apexes; a counterweight mechanism consists of a stud bolt, a T-shaped bolt, a counterweight block, a counterweight carcass, a closing bolt, a gland and a top tray; the counterweight block is fixed on the counterweight carcass through the stud bolt and the T-shaped bolt; the counterweight carcass is connected with the top tray through the closing bolt; and the left side of the workpiece is provided with a boring and milling power head, and the lower side and the outer side of the workpiece are provided with slide ways. A finished workpiece is obtained by adopting the tooling equipment and the processes of determining the position of a central hole, drilling the central hole, fixing the workpiece, determining the longitudinal position of the boring and milling power head, determining the transverse position of the boring and milling power head, processing the rest frame stations, checking and warehousing.
Owner:TONGYU HEAVY IND

Good-stability height ascending device for electric power projects

InactiveCN108793027AImprove skid resistanceConvenient for working on heightsLifting devicesRest frameEngineering
The invention belongs to the technical field of height ascending devices, in particular to a good-stability height ascending device for electric power projects. In order to solve the technical problems that time and labor are wasted during height ascending of a worker, and accidents are prone to occurrence when the worker moves on a working table, the good-stability height ascending device in thescheme comprises a base plate and a steel plate, two supporting plates are fixed to the outer wall of the top of the base plate through screws, one top plate is fixed to the outer walls of the tops ofthe two supporting plates through screws, a rotating round hole is formed in the position, close to the middle, of the outer wall of the top of the top plate, two first protection rods are fixed to one side of the outer wall of the top of the top plate through screws, and two second protection rods are fixed to the outer walls of one sides of the supporting plates through screws. The good-stability height ascending device is exquisite in appearance and convenient to operate; a height ascending ladder, a pedal plate, an anti-sliding block and an arm-rest frame are arranged, so that the workercan conveniently conduct height ascending work, the anti-sliding block has the very good anti-sliding effect, and safety of the height ascending work of the worker is improved.
Owner:南京奥新可工程科技有限公司

Multifunctional bionic tree tower

The invention provides a multifunctional bionic tree tower. The multifunctional bionic tree tower comprises a lightning rod, bionic branches, an upper tower pole, two or more retainer sleeves, a maintenance platform, a rain-proof shed, a maintenance ladder, a lower tower pole, a sightseeing platform, a support, a base, a crawling ladder, two arm-rest frames and a safety door; the upper tower pole is arranged at the lower end of the lightning rod, the retainer sleeves are installed on the upper tower pole, the bionic branches are installed at the upper ends of the retainer sleeves, the rain-proof shed is arranged at the lower end of the maintenance platform, the lower tower pole is installed in the middle of the lower end of the maintenance platform, the maintenance ladder is arranged on the lower tower pole, the support is arranged at the lower end of the sightseeing platform, the base is installed at the lower end of the support, the safety door is arranged on the right end face of the sightseeing platform, the crawling ladder is arranged at the lower end of the safety door, the arm-rest frames are symmetrically fixed at the front end and the rear end of the crawling ladder, and the top end of the crawling ladder is fixed at the right end of the sightseeing platform. The multifunctional bionic tree tower achieves the multifunctional effect, use is convenient, maintenance is convenient, the structure is simple, the functionality is improved, the stability is good, and the reliability is high.
Owner:HENGSHUI JIELIAN STEEL STRUCTURE
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