36results about How to "Meet noise requirements" patented technology

The invention discloses an air duct system of a reliability test bed for a drive line of a high-speed motor train unit, aiming at solving the problem that the service life of the test bed is greatly influenced when heat cannot be exhausted and dissipated timely. The air duct system of the reliability test bed for the drive line of the high-speed motor train unit comprises an air duct cement foundation (A), a cooling fan system (B), an air inlet cylinder system (C) and an air outlet cylinder system (D). The air inlet cylinder system (C) is fixedly arranged on the right end of the air duct cement foundation (A) by an air-inlet pre-embedded anchor hook square-shaped plate (h) pre-cast in the air duct cement foundation (A), the cooling air system (B) is arranged on a middle position of the air duct cement foundation (A) by a fan interface fixing frame assembly body (c) and a cooling fan damper assembly body (b) which are pre-cast in the air duct cement foundation (A), and the air outlet cylinder system (D) is arranged on the left end of the air duct cement foundation (A) through an air outlet duct welding plate (k) pre-cast in the air duct cement foundation (A).

The invention provides a noise prediction and layout optimization method for a flat terrain wind power plant. The noise prediction and optimization layout method for the flat terrain wind power plantcomprises the following steps that 1, on the basis of a wind power plant engineering wake flow model, generating the incoming flow wind speed of each wind turbine in the wind power plant, and calculating the aerodynamic noise source of each wind turbine; 2, simplifying the three-dimensional PE parabolic equation, and calculating a wind turbine noise propagation database based on a two-dimensionalnoise propagation equation of a single wind turbine; Step 3, according to the wind turbine noise propagation database obtained in the step 2, carrying out wind power plant noise numerical simulation calculation by using a wind power plant noise propagation multidimensional interpolation formula; And 4, optimizing the optimized layout of the wind power plant meeting the sound pressure level contourline by adopting a maximum sound pressure boundary value taking method.

Embodiments of the present application provide a control method, device, terminal, and medium for a graphics card fan, which relate to a graphics card heat dissipation technology, and are used to overcome the problem that it is difficult to achieve both good heat dissipation effect and noise reduction in related technologies. The control method includes: obtaining the current temperature of the graphics card, determining the current temperature deviation of the graphics card; the current temperature deviation is the difference between the current temperature and the set temperature; determining the pulse width modulation PWM duty cycle according to the current temperature deviation Duty ratio: when the PWM duty ratio exceeds the maximum duty ratio corresponding to the noise requirement, the speed of the graphics card fan is controlled according to the maximum duty ratio.

The invention discloses a composite cold pressing, synthesizing and cementing carrier roller which comprises combination sealing devices, a pipe base, check rings, bearings, spacer rings and a shaft. The shaft penetrates the pipe base, the spacer rings and the bearings are arranged at the two ends of the shaft, and the bearings are fixed to the two ends of the shaft through the check rings. The combination sealing devices penetrate the shaft to be in interference connection with the pipe base to be arranged at the two ends of the shaft. The pipe base is formed by connecting a pipe and bearing pedestals into a whole in a cold pressing, synthesizing and cementing manner, the pipe is made of a straight-line electric welding steel pipe special for an ultrahigh-precision carrier roller through inner and outer pipe rust prevention treatment. The bearing pedestals are made of polyformaldehyde through one-time injection moulding. The production procedure of the bearing pedestals is simplified, the precision of the finished bearing pedestals is improved, the weight is low, and strength is high; and the assembling mode of the bearing pedestals and the steel pipe is simplified, noise is lowered, and the carrier roller is applied to the field of bulk material conveying equipment.

The invention provides a spacecraft ultra-quiet environment simulating and testing system, which includes a crane, a sound absorbing structure, a sound insulation wall, a mass block, an air spring isolator, a vibration isolation track, a laboratory ground base, a sound insulation door, a maintenance channel, a vibration isolation channel, and a fine sand cushion. The sound insulation wall and the laboratory ground base are connected through the vibration isolation track; the mass block and the laboratory ground base are connected through the air spring isolator; the sound absorbing structure and the sound insulation wall are fixedly connected; the crane is located above the mass block; the internal part of the laboratory ground base is provided with the maintenance channel; the sound insulation wall and the sound absorbing structure are connected; the vibration isolation channel is connected with the fine sand cushion. The system of the invention is capable of increasing isolation effect of ground vibration and transverse vibration, increasing the sound insulation effect of the wall, enhancing the isolation effect of air and sound, effectively reducing the background noise in a testing area, meeting the background noise requirement in micro-vibration test and the environmental interference suppression requirement, increasing the isolation effect of the testing area to sounds of solid objects and providing advanced micro-vibration testing means to a high precision large scale spacecraft.

The embodiment of the invention provides a switching frequency control method and device of an inverter and a computer readable storage medium. The method comprises the steps: controlling the switching frequency of the inverter to perform random frequency conversion within the frequency conversion range corresponding to the current cycle within the current cycle; obtaining the operating noise amplitude of the inverter in the preset period of the current cycle; increasing the frequency conversion range corresponding to the next cycle when the operating noise amplitude is higher than the presetnoise amplitude threshold; and using the frequency conversion range of the current cycle as the frequency conversion range corresponding to the next cycle when the operating noise amplitude is lower than or equal to the noise amplitude threshold. The frequency conversion range which meets the noise requirement can be found by continuously cycling so that the switching frequency of the inverter israndomly converted within the frequency conversion range which meets the noise requirement, the noise requirement can be met and thus the noise generated by the inverter can be effectively reduced without changing the structure of the inverter or additionally arranging sound isolation and absorption measures.

The invention provides a low-noise friction material and a preparation method thereof, which solves the problem that the existing brake pad friction material will generate relatively large noise during the braking process, control the braking noise is unstable, and cannot fully meet the performance requirements of automobiles technical issues. Its components include polytetrafluoroethylene powder and filler material, the filler material includes inorganic filler and polymer filler, the inorganic filler is a solid lubricant, and the polymer material is a material that does not damage the dual surface and is easy to be machined. . The invention can be widely used in braking system.

The invention provides a noise assessment and noise optimization method and device for an electric reactor. The noise assessment method for the electric reactor comprises the steps that basic parameter information of each coil in a to-be-measured electric reactor is acquired; according to the basic parameter information, the maximum displacement of each coil is calculated respectively; according to the maximum displacement and the basic parameter information, an effective value of the vibration velocity of each coil is calculated; according to the effective value of the vibration velocity of each coil, the noise level of the to-be-measured electric reactor is evaluated. The noise assessment and noise optimization method and device for the electric reactor have the advantages that the problem that the noise cannot be evaluated in the early design phase of the electric reactor, the assessment method is simple and effective, a basis is provided for performing noise optimization on the electric reactor subsequently, and the noise assessment and noise optimization method and device have guiding significance for noise reduction design of a smoothing reactor.

The invention discloses a fine dimming device for a light emitting diode (LED) module. According to the device, a first pulse width modulation (PWM) signal output interface of the central processing unit (CPU) is connected with a signal input end of a first field-effect transistor; a signal output end of the first field-effect transistor is connected with a control end of the LED module through a current-limiting module; a second PWM signal output interface of the CPU is connected with a signal input end of a second field-effect transistor; and a signal output end of the second field-effect transistor is connected with the control end of the LED module. A dimming method comprises the following steps of: 1, judging whether luminosity corresponding to the light illumination which is required to be output by the LED module is greater than 5 percent of the maximum luminosity of the LED module; 2, if the luminosity is not greater than 5 percent of the maximum luminosity of the LED module, controlling the LED module to illuminate through a first PWM control signal by the CPU; and 3, if the luminosity is greater than 5 percent of the maximum luminosity of the LED module, controlling the LED module to illuminate after the first PWM control signal and the second PWM control signal which are sent by the CPU are superposed. According to the method, the ratio of the minimum illumination output to the maximum illumination output exceeds 1:10,000, so the dimming fineness of the LED module is guaranteed.

The invention relates to an ultra-thin, low-noise, energy-saving window-sill air supply system for improving the indoor environment. The air supply unit includes a cabinet-shaped outer cover and a fan coil unit built in the outer cover; The air outlet panel is horizontally set on the upper end surface of the outsourcing steel frame; the decorative plate is vertically set in front of the outsourcing steel frame, and there is a return air panel hanging on the outsourcing steel frame below it; the fan coil unit includes a bottom bracket, erected on The fan coil body on the bracket and the air-conditioning water pipe protruding from the fan coil, and a storage cabinet is arranged between two adjacent fan coil bodies. The advantages of the present invention are: the air supply units are arranged in a row along the curtain wall, and the air outlets thereof face upward, which can effectively remove the water mist on the glass curtain wall, and the air-conditioning water pipes are arranged in the storage cabinet between the two air supply units. It no longer occupies the space on the back of the fan coil unit, greatly increases the effective area of ​​the room, and reduces the thickness of the air supply device.