42results about How to "Avoid spending" patented technology

The invention discloses a data processing method and device. The data processing method comprises the steps that first attitude data of a one-dimensional beam corresponding to a flexible rod cylinder assembly, first grid data of a three-dimensional surface grid of the flexible rod cylinder assembly and fluid parameters associated with fluid acting on the flexible rod cylinder assembly are obtained; calculating a current hydrodynamic load based on the first attitude data, the first grid data and the fluid parameters; acquiring second attitude data of a one-dimensional beam corresponding to the flexible rod cylinder assembly deformed by applying the current hydrodynamic force load; and on the basis of the first attitude data, the first grid data and the second attitude data, a deformation vector of a three-dimensional surface grid of the flexible rod cylinder assembly deformed by applying the current hydrodynamic force load is calculated, and the deformation vector is used for representing the deformation degree of the flexible rod cylinder assembly.

The utility model relates to the technical field of electroplating rollers, in particular to electroplating roller equipment with high spraying efficiency, which comprises an electroplating box body placed on the ground, the outer wall of the electroplating box body is fixedly connected with a first motor, and the first motor is connected with a lifting block through a lifting structure; and the outer wall of the lifting block on the right side is fixedly connected with a mounting frame, the top end of the mounting frame is fixedly connected with a second motor, the second motor comprises an electroplating roller through a rotating structure, and a hollow cover is arranged on the electroplating roller. According to the electroplating device, the lifting structure and the rotating structure are matched with each other, so that the top threaded rod of the electroplating roller can be driven by the first motor to rotate so as to push the lifting block and the electroplating roller to move up and down, and the mounting frame fixed beside the lifting block can drive the rotating structure to move up and down at the same time; therefore, the problem that the electroplating roller cannot be lifted is solved, the production efficiency is greatly improved, and the production cost of a factory is greatly reduced.

The utility model relates to the technical field of agricultural product screening devices, and discloses an agricultural product primary processing screening device convenient to clean, which comprises a shell I, a screen is arranged in an inner cavity of the shell I, a vibration motor is fixedly mounted at the bottom of the screen, and fillets are fixedly mounted at the bottom of the screen and located on the left side and the right side of the vibration motor respectively. Grooves are formed in the bottoms of the fillets, sliding grooves are symmetrically formed in the left portion and the right portion of an inner cavity of the first shell, cavities are formed in the bottoms of the sliding grooves, electromagnets are fixedly installed at the bottoms of inner cavities of the cavities, springs are fixedly installed at the positions, located on the left sides and the right sides of the electromagnets, of the bottoms of the inner cavities of the cavities correspondingly, and movable plates are fixedly installed at the telescopic ends of the springs; and through clamping of an electromagnet power-on and power-off adjusting limiting block and a groove, the screen mesh is convenient to disassemble and assemble, so that the screening mechanism is cleaned, a large amount of time is prevented from being consumed, the working efficiency of the device is prevented from being influenced, maintenance of the device is facilitated, the maintenance efficiency is improved, and the failure rate of the device is reduced.

The application discloses a kind of photovoltaic module laminating edge trimming shaping mechanism, including the base of the center groove being set in the center of top, the liftable platform is arranged in the center groove, lifting cylinder is installed in the platform lower side, the mounting seat of two groups of side channel is slidably installed in the base top, the sliding block of the mounting seat bottom is clamped in the sliding slot of base top, the transverse moving cylinder is connected in the sliding block side, the edge trimming mechanism is arranged in the channel.The application can conveniently replace and install edge trimming cutter, reduce the operation difficulty, and the device is provided with two groups of edge trimming mechanism in a unit, when one group of edge trimming cutter is damaged, the purpose of automatic reversing can be realized by the adjustment of rotary motor, so that the processing can be continued by the other group of edge trimming cutter for standby, so that the processing efficiency can be effectively guaranteed.

The utility model discloses winnowing drying equipment for powder coating, which relates to the technical field of winnowing drying equipment and comprises a fixing ring, a heat preservation drying structure and an adjusting structure. A sealing cover is rotated to be separated from a feeding pipe, then the powder coating is poured into a feeding box from the feeding pipe, and the powder coating in the feeding box enters a discharging box through a third filtering plate, enters the upper end of a second filtering plate through a first filtering plate on an upper fixing circular ring and finally falls into a heat preservation box. The powder coating in the heat preservation box is dried through the electric heating wire, heat preservation is conducted on the heat preservation box through the heat preservation plate, after the powder coating in the heat preservation box is dried, a handle is pulled, then a baffle is driven to be opened, and the powder coating can slide out of a discharging opening; when the powder coating falls on the first filter plate, the rotating handle is rotated, the rotation of the rotating handle drives the second filter plate to rotate, and when the second filter plate rotates by a certain angle, the falling amount of the powder coating can be blocked.

The invention discloses an image rendering method and device, a storage medium and electronic equipment. The method comprises the steps that baking operation is conducted on a virtual object model based on the light source direction of a virtual light source, a first color map, a first depth map and a first coordinate set are obtained, the virtual object model is a three-dimensional model, and the virtual object model is within the shooting range of a first virtual camera; coordinates of all points in the virtual object model under the target coordinate system are obtained, and a second coordinate set is obtained; according to the first depth map, the first coordinate set and the second coordinate set, shadow information corresponding to the virtual object model is determined, and the shadow information is used for representing shadow values of all points in the virtual object model under the target coordinate system; and according to the first color map, the first coordinate set and the shadow information, performing rendering processing on the virtual object model to obtain a first target rendering image. The technical problem of low efficiency in the image rendering process is solved.

The present disclosure provides a high-rate lithium iron phosphate positive electrode material comprising lithium iron phosphate and carbon coated on a surface of the lithium iron phosphate, wherein a primary particle of the material has a particle size of 30-70 nm. The material of the present disclosure has a small and uniform primary particle size, no large single crystal particles, and a high specific surface area, and the battery prepared with the material has a high capacity, good cycle performance, excellent rate performance and low temperature performance. The present disclosure also provides a method for preparing the high-rate lithium iron phosphate positive electrode material, which has a simple process, is environmentally friendly, does not need precursors or expensive equipment, and has low cost.

The application provides a thyristor-based multi-port hybrid DC circuit breaker and a control method, comprising: a plurality of main branches and a shared branch; all the main branches are connected to the shared branch; the shared branch comprises a first thyristor branch, a power supply side circuit breaker unit and a fault side circuit breaker unit, the thyristor branch is used for bearing fault current in the process of breaking of a fast mechanical switch in the main branch; the fault side circuit breaker unit is composed of a first capacitor, a first discharge resistor and a first lightning arrester element in parallel connection; the power supply side circuit breaker unit is composed of a second thyristor branch, a current limiting resistor, a second capacitor, a second discharge resistor and a second lightning arrester, wherein the second capacitor, the second discharge resistor and the second lightning arrester are connected in parallel to form a second branch, the thyristor branch and the current limiting resistor are connected in series to form a first branch, and the first branch is connected in series to the second branch.

A water circuit switching plug and a constant temperature reverse water inlet switching structure, the water circuit switching plug is composed of a switching plug A and a switching plug B, respectively, the switching plug A comprises a mounting base and a circular block, the circular block is connected to the mounting base, and a sealing ring is provided on the outer periphery of the circular block; the switching plug B comprises a mounting base and a circular block, the circular block is connected to the mounting base via a thin diameter rod, the diameter of the thin diameter rod is smaller than the diameter of the mounting base, and at least one sealing ring is provided on the outer periphery of the circular block; the diameter of the mounting base is greater than or equal to the circular block, the outer diameters of the circular blocks of the switching plug A and the switching plug B are the same, the water inlet direction of cold and hot water can be easily changed by using the switching plug A and the switching plug B interchangeably, without the need to disassemble and reinstall in the event of a wrong direction.

The utility model provides a knee joint assembly and an exoskeleton device. The knee joint assembly comprises a base, a transmission shaft, a gear and a locking piece. A mounting hole is formed in the base, and a plurality of positioning grooves are formed in the inner wall of the mounting hole; a convex positioning part is arranged on the transmission shaft; the gear is arranged on the transmission shaft; and the locking piece is movably arranged on the base and is clamped with a tooth groove of the gear so as to lock the transmission shaft in the mounting hole. According to the knee joint assembly, the locking piece and the gear structure are matched to lock the transmission shaft, and then the locking angle between the two leg assemblies of the lower limb assembly of the exoskeleton is locked, so that the knee joint of an employee is supported, and the situation that the knee joint of the employee is frequently bent, so that a large amount of physical strength is consumed, and cartilage is damaged is avoided; and the positioning part and the positioning groove can improve the position stability between the base and the transmission shaft, the stress of the locking piece is reduced, and the stability of the locking piece for locking the gear can be improved.

According to the hydraulic drive-by-wire multi-shaft steering system and the control method thereof, when it is detected that a vehicle is in a high-pressure state, all constant displacement pumps are controlled to be in an open state; if the steering request is received and all the metering pumps are in the open state, all the stop valves are controlled to be in the closed state, and the total flow of hydraulic oil needed for steering is determined according to the steering request; the total flow of hydraulic oil required by steering is distributed to all the metering pumps; controlling each constant displacement pump to extract hydraulic oil from the oil tank; and according to the opening degrees of all the proportional valves in the executing mechanism, all the extracted hydraulic oil is distributed to steering oil cylinders corresponding to all the proportional valves to control a wheel steering mechanism to rotate. The stop valve is controlled to be in a closed state only when steering is needed, so that redundant electric energy is prevented from being consumed during straight driving, and the economical efficiency of the system is improved; the flow of the hydraulic oil is accurately controlled through a plurality of metering pumps; effective switching of hydraulic oil ways is achieved based on the multiple stop valves, and the reliability and safety of the system are improved.

The invention provides a method for preparing a multifunctional composite flocculant from pyrolysis carbonized slag, and relates to the technical field of solid waste treatment. The method comprises three steps of magnetic separation, catalytic activation and acid dissolution oxidation. The method comprises the following steps: firstly, removing impurities in the pyrolysis carbide slag through magnetic separation; then, adding an activating agent zinc chloride solution and a catalyst, and carrying out high-temperature reaction in an inert atmosphere to obtain iron-containing activated carbon; and finally, carrying out acid dissolution oxidation, and adding iron-containing waste hydrochloric acid and an oxidizing agent to prepare the multifunctional composite flocculant. The flocculant has double effects of adsorption and flocculation, is particularly suitable for treating high-COD and high-chroma wastewater, can effectively improve the COD removal rate and the decoloration effect, and has obvious advantages in removal effect compared with a conventional ferric chloride water treatment agent. The method provided by the invention not only has low energy and high efficiency, but also prepares the water treatment flocculant which can be directly applied, and realizes efficient and clean utilization of solid waste.

The utility model relates to the technical field of fixed pivot, and disclose a kind of fixed pivot device convenient for reuse, including connector, connector outer edge rotatably installed with connecting sleeve one and connecting sleeve two, the one end of connecting sleeve one away from connector is fixedly installed with fixed sleeve one, the inner thread one is set in the inner side of fixed sleeve one, the threaded hole one is set in the outer side of fixed sleeve one, the one end of connecting sleeve two away from connector is fixedly installed with fixed sleeve two, the inner thread two is set in the inner side of fixed sleeve two, the threaded hole two is set in the outer side of fixed sleeve two.The fixed pivot device convenient for reuse, by the design of inner thread one and inner thread two, connecting sleeve one and connecting sleeve two can be threadedly connected with pivot, before experiment, avoid consuming more manpower and material resources, and after experiment is completed, the quick disassembly of connecting sleeve one and connecting sleeve two can be realized, and subsequent reuse can be facilitated.

This utility model discloses an automatic sludge airlift collection device, relating to the field of sludge collection technology. It includes a water tank, with first chutes extending through the upper ends of both the front and rear sides. Slide plates are slidably connected inside the two sets of first chutes. A first push rod is fixedly installed on the upper right side of the water tank. A second chutes extend through the upper side of the slide plates, with an I-shaped slider slidably connected inside the second chutes. Connecting plates are fixedly connected to both ends of the slide plates, extending through the interior of the first chutes. A second push rod is fixedly installed on the front side of the front connecting plate. An airlift pipe is rotatably connected to the upper center of the I-shaped slider. This utility model, by setting up the first chutes, second chutes, slide plates, I-shaped sliders, first push rods, second push rods, and a sludge suction nozzle, can effectively collect sludge from all locations at the bottom of the water tank, preventing excessive sludge residue in certain areas, ensuring wastewater treatment efficiency, and reducing the workload of subsequent wastewater treatment.

The utility model relates to building steel structure technical field especially relates to a kind of center support frame structure that avoids hole and is easily repaired, including frame beam, frame column and center support;Two parallel frame beams and two parallel frame columns constitute square frame, one frame beam includes durable section and vulnerable section, and durable section and vulnerable section are hinged connection;The center support includes support section and avoidance section, the support section is arranged obliquely, and support section is connected with the connecting point of frame beam and frame column, the avoidance section is connected with the connecting point of diagonal frame beam and frame column, and avoidance section is installed in the vulnerable section, for avoiding the hole in square frame. Through the utility model, the problem that traditional center support oblique support section hinders door and window hole and traffic streamline and the problem that it is difficult to repair after damage are solved.

The embodiment of the present application discloses a method and device for determining the amount of fluid to be returned during the braking process of a vehicle. The method at least includes: determining the driving distance corresponding to the consumption of all brake fluid by the vehicle during the deceleration process of the vehicle; determining the current speed and current deceleration of the vehicle when the anti-lock braking system (ABS) of the vehicle is triggered; calculating the braking distance required for the vehicle to stop from the current speed according to the current deceleration; determining the total amount of brake fluid in the vehicle, and calculating the amount of fluid to be returned required by the vehicle according to the total amount of brake fluid, the driving distance and the braking distance. By applying the solution provided in the embodiment of the present application, the amount of brake fluid that needs to be returned can be determined according to the actual driving conditions during the braking process of the vehicle, thereby avoiding the process of returning too much brake fluid, which takes a long time. Therefore, the braking time of the vehicle can be shortened and the braking efficiency can be improved.

The present application provides a carbon material, a preparation method therefor and the use thereof, a negative electrode plate, a secondary battery, and a power consuming device. The carbon material comprises a porous carbon substrate and an amorphous carbon layer provided on at least part of a surface of the porous carbon substrate. When the carbon material is used as a negative electrode active material, it can make full use of the abundant porous structures in the porous carbon substrate for lithium / sodium precipitation or lithium / sodium intercalation and avoid the side reactions due to the contact between the abundant active sites on the surface of the porous carbon substrate and an electrolyte solution, such that the initial coulombic efficiency and the actual capacity of a secondary battery can be improved.

The application discloses a host risk evaluation method and an evaluation device. The evaluation method comprises the following steps: obtaining historical data in a host cycle, wherein the historical data comprises static data and dynamic index data; inputting the static data and the dynamic index data into a trained risk prediction model, and predicting a risk evaluation value of the host by using the risk prediction model, wherein the risk prediction model is used for evaluating the risk of the host according to the static data and the dynamic index data; and obtaining a prediction result output by the risk prediction model, and obtaining the risk evaluation value of the host.

The present application provides an object grasping method based on object poses, which comprises: obtaining a first object pose of a first target object, wherein the first target object comprises an object determined from N objects to be grasped; calculating a pose distance between the first object pose and at least one of M second object poses, wherein the M second object poses comprise object poses of M objects that fail to be grasped from the N objects to be grasped, M or N is an integer greater than or equal to 1, and M is less than or equal to N; and stopping grasping the first target object if any of the calculated pose distances is less than a first distance threshold. The present application also provides an object grasping device based on object poses, an electronic device and a storage medium.

The application provides a method for preparing multifunctional composite flocculants by using pyrolysis carbonized slag, and relates to the technical field of solid waste treatment. The method comprises three steps of magnetic separation, catalytic activation and acid dissolution oxidation. First, impurities in the pyrolysis carbonized slag are removed through magnetic separation; then, an activator zinc chloride solution and a catalyst are added, and a high-temperature reaction is carried out under an inert atmosphere to obtain iron-containing activated carbon; finally, acid dissolution oxidation is carried out, iron-containing waste hydrochloric acid and an oxidizing agent are added, and multifunctional composite flocculants are prepared. The flocculants have the dual effects of adsorption and flocculation, and are particularly suitable for treating high-COD and high-color wastewater, can effectively improve the COD removal rate and the decolorization effect, and have obvious advantages compared with the removal effect of conventional ferric chloride water treatment agents. The method provided by the application is low-energy and high-efficiency, and a water treatment flocculant that can be directly applied is prepared, and efficient and clean utilization of solid waste is realized.

The utility model relates to the technical field of soil detection, and discloses a soil quick-drying device for soil detection, the top end of a vibrating plate is provided with a supporting mechanism, the supporting mechanism is internally provided with a moisture absorption mechanism for assisting soil quick-drying, the top end of the vibrating plate is provided with a water storage assembly for receiving water, and the water storage assembly is internally provided with a moisture absorption mechanism for assisting soil quick-drying. According to the soil quick-drying device, through cooperation of the moisture absorption mechanism and the drying mechanism, preliminary moisture absorption pretreatment can be conducted on wet soil through the conical moisture absorption pad, the quick-drying speed of the soil is increased, and the subsequent quick-drying efficiency of the drying mechanism on the soil is improved; and after moisture absorption of the wet soil is achieved, the draught fan and the electric heating box are started, after the electric heating box heats air, the draught fan blows hot air into the annular box through the bent pipe, at the moment, the vibrating wet soil can be matched with moisture absorption of the conical moisture absorption pad and drying of the hot air, and the quick drying speed of the soil is increased.

The invention discloses a power grid enterprise power purchase and sale joint strategy optimization method and system based on MADDPG, and the method comprises the steps: constructing a power purchase decision model of a power grid company in a spot market and a supply model of the power grid company at a user side, and considering the power supply deviation loss of the power grid company, and obtaining a joint decision objective function of the power grid company; and on the premise that the intelligent agents are trained through a multi-intelligent-agent algorithm, optimal strategies for power purchase and load prediction are given respectively, and a reinforcement learning algorithm MADDPG is adopted, so that the objective fact that a power grid company is difficult to obtain all user information is met, and meanwhile, a large amount of calculation power consumed by modeling prediction is avoided; through mutual strategy approximation of the two agents, the dynamic stability of the agent training process is ensured, and the algorithm efficiency and the model solving effect are improved.

The invention relates to the technical field of energy supply, and discloses a plateau village and town wind, light, generation and storage multi-energy complementary micro-grid dynamic optimization system and method, and the system comprises a photovoltaic power generation module which employs solar energy to generate power so as to supplement daytime load demands; the wind power generation module converts wind energy into electric energy as renewable energy source base load; the biomass energy module is used for generating power by utilizing agricultural wastes so as to provide controllable base load; the energy storage module is used for stabilizing power fluctuation, storing surplus electric energy and releasing the surplus electric energy at a load peak; the dynamic complementation module is used for generating biomass energy generating capacity, energy storage charging and discharging capacity and interaction capacity with a large power grid on the basis of wind speed / illumination prediction and a load curve of the next day by taking minimization of total cost as a principle; the technical problems that in plateau villages and towns, wind power and photovoltaic power generation are intermittent and unstable, and stable energy supply cannot be met are solved.

The utility model belongs to the technical field of sorting devices, and particularly relates to a tobacco leaf weighing and sorting device which comprises a step-shaped table body, a motor frame and a supporting frame, the motor frame and the supporting frame are both fixedly connected to one side of the upper end of the step-shaped table body, the sorting device further comprises a conveying mechanism, and the conveying mechanism is located on the step-shaped table body. The conveying mechanism is used for conveying the sorted tobacco leaves; the sorting mechanism is located at the upper end of the stepped table body, the sorting mechanism is used for screening tobacco leaves, and the conveying mechanism comprises two connecting shafts, two rotating sleeves, a transmission belt, a stepping motor, a weight sensing unit and a storage box; according to the tobacco leaf sorting device, through mutual cooperation of the conveying mechanism and the sorting mechanism, excessive consumption of manpower can be effectively avoided, and the situation that a worker pays attention to tobacco leaves all the time and consumes a large amount of energy is effectively avoided.

The present application provides a data processing method and storage system, which relate to the field of storage. The method includes: a metadata server receives a first instruction from a recycle bin management server; based on the first instruction, the first data is identified as an abnormal state; when the system overhead meets a preset condition, the first data identified as an abnormal state is cleared from the recycle bin. Based on the data processing method provided by the present application, expired but not cleared data is identified as an abnormal state and is not included in the tenant's billing space, and when the system overhead meets the preset condition, the data identified as an abnormal state is cleared. Therefore, the strategy of clearing expired data in the recycle bin is optimized, while reducing the impact on system performance, without increasing the tenant's storage space occupation time, avoiding unnecessary expenses for the tenant.

The invention discloses a feeding device of a sampling pipe and a detection system, and relates to the technical field of grain detection, the feeding device comprises a storage disc, a telescopic assembly, a clamping assembly and a driving assembly, the telescopic assembly comprises a first arm body and a second arm body which are connected with each other, and the second arm body is slidably arranged relative to the first arm body; the clamping assembly is slidably connected with the second arm body, the driving assembly is fixed to the first arm body, and the material storage disc can contain a sampling pipe. When the telescopic assembly is idle, other space except the containing space is not occupied, and the size of the feeding device is not affected. When the telescopic assembly works, the telescopic assembly can enable the clamping assembly to complete multi-section movement in the first direction or the second direction through the multi-stage telescopic structure of the first arm body and the second arm body, and the carrying range of the clamping assembly is farther. The multi-stage telescopic arrangement improves the integration level of the feeding device, reduces the size of the feeding device and expands the application range of the feeding device on the premise of ensuring that the clamping assembly has an enough carrying range.

The present invention belongs to the technical field of information management in the completion and closing stage, and relates to an information management system for the completion and closing stage based on engineering projects. The present invention increases the transparency and traceability of engineering projects by analyzing the file flow compliance indicators and file content compliance indicators of each type of files corresponding to each file of the target engineering project, which is conducive to timely discovering and correcting non-compliant behaviors in the information management of engineering project files, ensuring the professionalism, accuracy and readability of engineering project files, and improving the compliance and quality of engineering projects. By analyzing the change gap indicators and expected gap indicators of each change file corresponding to each type of file of the target engineering project, it is helpful to timely discover and solve problems in engineering project management, and help project managers to effectively control multiple angles such as cost, project progress, engineering quality and risk management, avoiding unnecessary waste and expenditure, and improving engineering quality.

The invention discloses a heald frame positioning and installing device which comprises a main body frame, a power and guide assembly and a positioning assembly, the power and guide assembly comprises a jack, a jack top plate, a guide shaft and a heald frame top plate, the jack is fixedly installed at the bottom in the main body frame, and the jack top plate is fixedly installed at the top end of an ejector rod of the jack; the guide shaft is fixedly mounted on the jack top plate and upwards penetrates through the top plate of the main body frame, and a heald frame top plate is fixedly mounted at the top end; the positioning assembly comprises a positioning rod, a positioning plate and a locking sleeve, the positioning rod is installed between the heald frame top plate and the jack top plate, the positioning rod is sleeved with the positioning plate and the locking sleeve, and the locking sleeve is located below the positioning plate. The device is simple in structure and convenient to operate, can assist manpower in completing height positioning installation of the heald frame, greatly reduces the physical labor of installation personnel, avoids operation danger, can reduce half of the installation personnel, improves the installation efficiency and precision, and ensures the product quality and consistency of the air jet loom.

This invention discloses an improved method for integrating electrocardiogram (ECG) and electroencephalogram (EEG) into one. Based on the existing ECG DB15 wiring sequence multiplexing circuit, it fully utilizes the reserved empty pins (NC pins) in the wiring sequence without changing the core definition of the original DB15 wiring sequence or affecting the original 12-lead ECG signal acquisition function. This achieves integrated reuse of the ECG / EEG interface and circuit, eliminating the need for an additional independent EEG interface and complex circuitry. Furthermore, this invention, through a built-in recognition module, can automatically identify whether the user has inserted an ECG or EEG cable and quickly switch the corresponding signal acquisition parameters, filtering modes, and data processing logic. This enables automatic switching between ECG and EEG acquisition functions without manual adjustment, making operation convenient and efficient. It effectively reduces the operational difficulty for medical personnel and minimizes detection errors caused by human error.

The invention relates to the technical field of heating equipment, and provides fast food heating equipment based on hot air. Comprising a box body assembly, a heating chamber assembly and a hot air machine assembly are arranged in the box body assembly, and a plurality of heating tray assemblies are arranged in the heating chamber assembly up and down; an air outlet in the hot air machine assembly is communicated with an air inlet of each heating tray assembly through the splitter plate assembly; the air outlet hole of each heating tray assembly is formed downwards, and hot air flowing out of the air outlet holes passes through the space between every two adjacent heating tray assemblies and then is collected into the air return duct. The heating tray assembly has the beneficial effects that the flow of hot air entering each heating tray assembly in unit time is equal through the splitter plate assembly, heat brought by the hot air entering each heating tray assembly can heat food on the upper portion through the bottom plate and can also flow out through the air outlet plate to heat food below the heating tray assembly, the food is evenly heated, and the heating efficiency is improved. And the food is uniformly heated from the upper direction and the lower direction, and the heating efficiency is high.