CN116301124A - Humidity control method, electronic equipment, medium and carbon dioxide incubator - Google Patents

Abstract

The invention relates to the technical field of biological culture equipment, in particular to a humidity control method, electronic equipment, a medium and a carbon dioxide incubator, and aims to solve the problem that the humidity in the carbon dioxide incubator is difficult to actively control. For this purpose, the humidity control method of the present invention comprises: acquiring the temperature in the incubator; and controlling the rotating speed of the speed-adjustable fan based on the temperature control so as to control the humidity in the incubator. According to the invention, the rotating speed of the adjustable speed fan is controlled based on the temperature in the carbon dioxide incubator, the condensation forming amount of the heat dissipation plate area is actively regulated, so that the control of the humidity in the incubator is realized, a humidity sensor is not required to be additionally arranged for feeding back the humidity, the open-loop control of the humidity is realized, the temperature is firstly controlled, then the humidity is controlled, the passive formation of the condensation in other positions in the incubator is systematically prevented, and the influence of the temperature on the humidity is reduced to the maximum extent; the humidity in the box can be controlled more accurately by adopting the technical effect of actively controlling the humidity, and the requirements of medical treatment and experiments are met.

Description

Humidity control method, electronic equipment, medium and carbon dioxide incubator

technical field

The invention relates to the technical field of biological cultivation equipment, and specifically provides a humidity control method, electronic equipment, a medium and a carbon dioxide incubator.

Background technique

As a high-end medical equipment, the carbon dioxide incubator can provide suitable temperature, humidity and carbon dioxide concentration for cultivating human tissues and cells. As a complex temperature control device, its temperature field and humidity field are superimposed together. There are heating wires on each side of the box for temperature control, and a certain amount of water is added to the bottom of the box for humidity control.

In the existing technology, the carbon dioxide incubator is basically a "passive humidification" type. The so-called passive means that during the temperature control process of the system, due to the temperature rise of the tank inner tank, the water will continue to evaporate, and the relative humidity will reach 90%, the highest. 96%, 97%, at this time, the condensation phenomenon is very easy to occur. The incubators on the market are basically based on temperature control, and there are few active humidity control solutions. Condensation is passively generated during the temperature control process. It is difficult to accurately control the temperature in the incubator simply by controlling the temperature to achieve humidity control.

Correspondingly, there is a need in the art for a new humidity control scheme for carbon dioxide incubators to solve the above problems.

Contents of the invention

In order to overcome the above-mentioned defects, the present invention is proposed to provide a humidity control method, a carbon dioxide incubator, electronic equipment and media to solve or at least partly solve the technical problem that the humidity in the carbon dioxide incubator is difficult to actively control.

In the first aspect, the present invention provides a method for controlling humidity, which is applied to a carbon dioxide incubator. The carbon dioxide incubator includes a cooling plate and an adjustable-speed fan, wherein the adjustable-speed fan passes through the heat dissipation provided on the incubator body. The plate blowing to adjust the temperature and heat dissipation efficiency of the heat dissipation plate includes: obtaining the temperature in the incubator; controlling the speed of the adjustable fan based on the temperature, so as to realize the control of the humidity in the incubator.

In a technical solution of the above humidity control method, controlling the speed of the adjustable fan based on the temperature to control the humidity in the incubator includes: when the temperature does not reach a preset threshold, the adjustable The speed-adjustable fan works at the maximum speed; when the temperature reaches a preset threshold, the speed-adjustable fan adjusts the speed according to the temperature fluctuation in the incubator.

In a technical solution of the above humidity control method, the method further includes obtaining the temperature fluctuation in the incubator at least through the following steps: taking the predetermined duration as a cycle, and measuring the temperature in the incubator multiple times in each cycle value, the interval between every two measurements is equal to the length of time; according to the temperature value in the incubator of multiple measurements, the average value of the temperature in the incubator of each cycle is obtained; the average value of the temperature in the incubator of each cycle is averaged Value, obtain the total average value; According to the average value and the total average value of the temperature in the incubator of each cycle, obtain the variance, and the value of the variance represents the temperature fluctuation degree in the incubator.

In a technical solution of the above humidity control method, the speed adjustment of the adjustable speed fan is realized by adjusting the output voltage of the controller, and the speed adjustment of the adjustable speed fan is performed according to the temperature fluctuation in the incubator, including: Adjusting the output voltage of the controller and measuring historical temperature data to obtain a linear relationship between the variance and the output voltage of the controller; adjusting the output voltage of the controller according to the current variance and the linear relationship.

In a technical solution of the above humidity control method, controlling the speed of the adjustable-speed fan based on the temperature to control the humidity in the incubator includes: controlling the speed of the adjustable-speed fan based on the temperature , to adjust the temperature and heat dissipation efficiency of the heat dissipation plate; when the temperature of the heat dissipation plate is lower than the temperature in the incubator, and the area near the heat dissipation plate reaches the saturated vapor pressure, the water vapor in the area near the heat dissipation plate Condensation is formed in the area of the heat dissipation plate; the water vapor in the incubator moves to the area near the heat dissipation plate, forms a certain amount of condensation, and then reaches the temperature and humidity balance, realizing the control of the humidity in the incubator.

In a technical solution of the above humidity control method, a heating wire for adjusting the temperature inside the incubator is arranged around the incubator body, and the temperature and humidity can be achieved by adjusting the power of the heating wire and the speed change of the speed-adjustable fan. The corresponding temperature and humidity at equilibrium.

In a second aspect, an electronic device is provided, the electronic device includes a processor and a memory, the memory is adapted to store a plurality of program codes, and the program code is adapted to be loaded and run by the processor to perform the above-mentioned humidity control The humidity control method described in any one of the technical solutions of the method.

In a third aspect, a computer-readable storage medium is provided, wherein a plurality of program codes are stored in the computer-readable storage medium, and the program codes are adapted to be loaded and run by a processor to perform the technical solution of the above-mentioned humidity control method The humidity control method described in any one technical solution.

In the fourth aspect, the present invention provides a carbon dioxide incubator, including an incubator body, a heat dissipation plate arranged on the incubator body, an adjustable-speed fan, a temperature collection device, a heating wire, and the above-mentioned electronic equipment, wherein the The temperature acquisition device is used to obtain the temperature in the incubator, the heating wire is used to adjust the temperature in the incubator, the adjustable-speed fan controls the speed of the adjustable-speed fan based on the temperature, and adjusts the temperature of the cooling plate. Temperature and heat dissipation efficiency to achieve the control of the humidity inside the incubator.

In a technical solution of the above-mentioned carbon dioxide incubator, the incubator further includes a controller, the controller is used to adjust the output voltage of the controller according to the temperature fluctuation in the incubator, so as to control the adjustable speed fan to adjust the rotation speed.

The above-mentioned one or more technical solutions of the present invention have at least one or more of the following

Beneficial effect:

In implementing the technical solution of the present invention, the speed of the adjustable fan is controlled based on the temperature in the carbon dioxide incubator, and the amount of condensation formed in the heat dissipation plate area is actively adjusted to realize the control of the humidity in the incubator, without additional humidity sensors Feedback on the humidity, realize open-loop control on the humidity, control the temperature first, then control the humidity, systematically prevent the passive formation of condensation in other positions in the incubator, and minimize the influence of temperature on the humidity; adopt the technical effect of actively controlling the humidity , can more accurately control the humidity in the box, to meet the needs of medical treatment and experiments.

In implementing the technical solution of the present invention, when the temperature reaches the preset threshold value, the speed-adjustable fan is adjusted according to the temperature fluctuation in the incubator, and the temperature and heat dissipation efficiency of the cooling plate are adjusted to achieve the temperature control of the incubator. Precise control of humidity balance.

Description of drawings

The disclosure of the present invention will become more comprehensible with reference to the accompanying drawings. Those skilled in the art can easily understand that: these drawings are only for the purpose of illustration, and are not intended to limit the protection scope of the present invention. In addition, like numerals are used to designate like parts in the drawings, wherein:

Fig. 1 is the flow chart of main steps of the humidity control method according to an embodiment of the present invention;

Fig. 2 is a detailed step flow chart corresponding to obtaining the temperature fluctuation degree in the incubator according to the humidity control method of the present invention;

Fig. 3 is a flow chart of detailed steps corresponding to controlling the speed of the adjustable-speed fan based on the temperature to realize the control of the humidity in the incubator according to the humidity control method of the present invention;

FIG. 4 is a main structural block diagram of an electronic device for performing the humidity control method of the present invention.

Detailed ways

Some embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention, and are not intended to limit the protection scope of the present invention.

In the description of the present invention, "module" and "processor" may include hardware, software or a combination of both. A module may include hardware circuits, various suitable sensors, communication ports, memory, and may also include software parts, such as program codes, or a combination of software and hardware. The processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor or any other suitable processor. The processor has data and/or signal processing functions. The processor can be implemented in software, hardware or a combination of both. The non-transitory computer readable storage medium includes any suitable medium that can store program code, such as magnetic disks, hard disks, optical disks, flash memory, read only memory, random access memory, and the like. The term "A and/or B" means all possible combinations of A and B, such as only A, only B or A and B. The term "at least one of A or B" or "at least one of A and B" has a similar meaning to "A and/or B" and may include only A, only B or both A and B. The terms "a" and "the" in the singular may also include plural forms.

The invention provides a humidity control method, which is applied to a carbon dioxide incubator. The carbon dioxide incubator includes a cooling plate and an adjustable-speed fan, wherein the adjustable-speed fan adjusts the Heat sink temperature and cooling efficiency.

Referring to accompanying drawing 1, Fig. 1 is a schematic flowchart of main steps of a humidity control method according to an embodiment of the present invention. As shown in FIG. 1 , the humidity control method in the embodiment of the present invention mainly includes the following steps S101 - S102.

Step S101, acquiring the temperature in the incubator.

In this embodiment, the temperature in the incubator is obtained through a temperature acquisition device installed in the incubator. Specifically, the temperature acquisition device is arranged inside the inner tank of the incubator, and when the temperature acquisition device uses a sensor probe to collect temperature data, the sensor probe does not directly contact the inner tank wall of the incubator, so that Accurately obtain the temperature of the gas in the incubator.

In one embodiment, multiple measurements are required to obtain the temperature in the incubator. Specifically, a predetermined period of time is taken as a cycle, and the temperature value in the incubator is measured multiple times in each cycle, and the acquisition of the temperature in the incubator is completed after multiple cycles of measurement.

Step S102, controlling the speed of the variable-speed fan based on the temperature, so as to control the humidity in the incubator.

In this embodiment, controlling the speed of the adjustable-speed fan based on the temperature to control the humidity in the incubator includes:

When the temperature does not reach the preset threshold, the adjustable speed fan works at the maximum speed;

When the temperature reaches the preset threshold, the speed-adjustable fan is adjusted according to the temperature fluctuation in the incubator.

Referring to accompanying drawing 2, Fig. 2 is a flow chart of detailed steps corresponding to obtaining temperature fluctuation in the incubator according to the humidity control method of the present invention. In one embodiment, the humidity control method further includes obtaining the temperature fluctuation in the incubator at least through the following steps S201-S204.

Step S201, taking the predetermined time length as a cycle, and measuring the temperature value in the incubator several times in each cycle, with an equal time interval between each two measurements.

Specifically, in one embodiment, the temperature value in the incubator is measured at an interval of 500 ms, and recorded 30 times in each period T, and the required duration of the 30 recordings is the predetermined duration. In actual operation, the predetermined duration, the number of measurements in each cycle, and the interval between each two measurements can be set by those skilled in the art according to the actual situation. The above-mentioned implementation is only an example and does not limit the scope of the present invention. .

Step S202, according to the temperature values in the incubator measured multiple times, the average value of the temperature in the incubator for each cycle is obtained.

In one embodiment, the average value of the temperature in the incubator in each cycle is the ratio of the sum of the temperature values measured each time in each cycle to the number of measurements in each cycle. The average value of the temperature in the first period box is recorded as aver1, the average value of the temperature in the second cycle box is recorded as aver2, and so on. In this embodiment, multiple cycles of temperature measurement are required to obtain the temperature fluctuation in the incubator.

In step S203, the average value of the temperature in the incubator in each period is averaged to obtain the total average value.

In one embodiment, if the number of cycles passed is N, the total average

Step S204, according to the average value and the total average value of the temperature in the incubator in each cycle, obtain the variance, and the value of the variance represents the temperature fluctuation in the incubator.

In one embodiment, the variance

Further, the speed adjustment of the adjustable-speed fan is realized by adjusting the output voltage of the controller, and it is characterized in that the speed-adjustable fan is adjusted according to the temperature fluctuation in the incubator, including:

Obtain the linear relationship between the variance and the output voltage of the controller according to the historical data of adjusting the output voltage of the controller multiple times and measuring the temperature;

The controller output voltage is adjusted according to the current variance and the linear relationship.

In one embodiment, the linear relationship is V=S ² *K+b(3), wherein V is the output voltage of the controller, K is a scaling factor, and b is a constant.

Specifically, in one embodiment, according to the historical data of adjusting the output voltage of the controller multiple times and measuring the temperature, a linear relationship V=6.5652*S ² +0.6802(4) is obtained; after obtaining the linear relationship, according to the current variance S ² and the linear relationship described in formula (4), adjust the output voltage V of the controller to dynamically adjust the temperature and heat dissipation efficiency of the cooling plate according to the temperature fluctuation, so as to realize humidity control. In actual operation, those skilled in the art can obtain different values of K and b according to the historical data of adjusting the output voltage of the controller multiple times and measuring the temperature, and bring them into the formula (3).

In one embodiment, the heat dissipation plate arranged on the incubator body, specifically, can be arranged on the side wall or the back plate of the incubator body, and the adjustable-speed fan is connected to the heat dissipation plate through an air duct. plate to blow air on it.

In implementing the technical solution of the present invention, when the temperature reaches the preset threshold value, the speed-adjustable fan is adjusted according to the temperature fluctuation in the incubator, and the temperature and heat dissipation efficiency of the cooling plate are adjusted to achieve the temperature control of the incubator. Precise control of humidity balance.

Specifically, the speed-adjustable fan is capable of stepless speed regulation. In one embodiment, the output voltage of the controller is steplessly regulated within the range of 0-10V, and the speed of the variable speed fan is steplessly regulated according to the output voltage of the controller, which can be accurately controlled as required .

Further, please refer to accompanying drawing 3. Fig. 3 is a flow chart of detailed steps corresponding to controlling the speed of an adjustable fan based on temperature to control the humidity in the incubator according to the humidity control method of the present invention. In one embodiment, controlling the speed of the adjustable fan based on the temperature to control the humidity in the incubator at least includes the following steps S301-S303.

Step S301, controlling the speed of the variable-speed fan based on the temperature to adjust the temperature and heat dissipation efficiency of the cooling plate.

The speed-adjustable fan blows air to the heat dissipation plate through the air duct to reduce the temperature of the heat dissipation plate; when the temperature of the heat dissipation plate is lower than the temperature in the incubator, the heat dissipation plate and the surrounding air are heated The heat dissipation efficiency of the exchange is also improved.

Step S302, when the temperature of the cooling plate is lower than the temperature in the incubator, and the area near the cooling plate reaches the saturated vapor pressure, the water vapor in the area near the cooling plate forms condensation in the area of the cooling plate .

In one embodiment, the area of the heat dissipation plate, that is, the area of the inner tank of the incubator corresponding to the heat dissipation plate, is the main area where condensation is formed, and is called an active condensation area. The setting of the active condensation area is used not only to adjust the humidity in the incubator, but also to prevent passive condensation in other positions in the incubator.

Step S303, the water vapor in the incubator moves to the area near the heat dissipation plate, forms a certain amount of condensation, and then reaches the temperature and humidity balance, so as to realize the control of the humidity in the incubator.

Specifically, heating wires are arranged around the incubator body to adjust the temperature in the incubator, and the temperature and humidity corresponding to temperature and humidity balance are achieved by adjusting the power of the heating wires and changing the speed of the speed-adjustable fan.

For the gas inside the incubator, the temperature of the cooling plate has little effect on the overall gas temperature inside, and the gas temperature is mainly adjusted by the heating wire; however, the cooling of the cooling plate will cause condensation in the active condensation area. The amount has a greater impact, so it plays a major role in the control of the humidity in the incubator.

In one embodiment, the heat dissipation plate is made of an aluminum plate, and the heat dissipation plate is arranged at a lower position on the back plate of the incubator body, so as to facilitate the inflow of condensation when condensation is formed in the inner tank of the incubator. In the tray at the bottom of the incubator.

Further, the position of the active condensation area is determined according to the installation position of the cooling plate in actual operation.

Based on the above step S101-step S102, in implementing the technical solution of the present invention, the speed of the adjustable fan is controlled based on the temperature in the carbon dioxide incubator, and the amount of condensation formed in the heat dissipation plate area is actively adjusted to realize the humidity in the incubator No need to set additional humidity sensor to feedback the humidity, realize open-loop control of humidity, first control temperature, then control humidity, systematically prevent passive condensation from forming in other positions in the incubator, and minimize the influence of temperature on humidity ; Adopting the technical effect of actively controlling the humidity, it can control the humidity in the box more accurately to meet the needs of medical treatment and experiments.

It should be pointed out that, although the steps are described in a specific order in the above embodiments, those skilled in the art can understand that in order to achieve the effect of the present invention, different steps do not have to be executed in this order. They can be performed simultaneously (parallel) or in other sequences, and these variations are within the protection scope of the present invention.

Those skilled in the art can understand that all or part of the process in the method of the above-mentioned embodiment of the present invention can also be completed by instructing related hardware through a computer program, and the computer program can be stored in a computer-readable In the storage medium, when the computer program is executed by the processor, the steps of the above-mentioned various method embodiments can be realized. Wherein, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device capable of carrying the computer program code, medium, U disk, removable hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electric carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable Storage media excludes electrical carrier signals and telecommunication signals.

Further, the present invention also provides an electronic device.

Referring to accompanying drawing 4, Fig. 4 is a main structural block diagram of electronic equipment for implementing the humidity control method of the present invention.

In an electronic device embodiment according to the present invention, the electronic device 400 includes a processor 401 and a memory, the memory 402 may be configured to store a program code 403 for executing the humidity control method of the above method embodiment, and the processor 401 may be configured to For executing the program code 403 in the memory, the program code 403 includes but not limited to the program code 403 for executing the humidity control method of the above method embodiment. For ease of description, only the parts related to the embodiments of the present invention are shown, and for specific technical details not disclosed, please refer to the method part of the embodiments of the present invention.

Further, the present invention also provides a computer-readable storage medium. In an embodiment of a computer-readable storage medium according to the present invention, the computer-readable storage medium may be configured to store a program for executing the humidity control method of the above-mentioned method embodiment, and the program may be loaded and run by a processor to realize the above-mentioned humidity control method. Control Method. For ease of description, only the parts related to the embodiments of the present invention are shown, and for specific technical details not disclosed, please refer to the method part of the embodiments of the present invention. The computer-readable storage medium may be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in this embodiment of the present invention is a non-transitory computer-readable storage medium.

Further, the present invention also provides a carbon dioxide incubator, including an incubator body, a cooling plate arranged on the incubator body, an adjustable-speed fan, a temperature collection device, a heating wire, and the above-mentioned electronic equipment, wherein the The temperature acquisition device is used to obtain the temperature in the incubator, the heating wire is used to adjust the temperature in the incubator, the adjustable-speed fan controls the speed of the adjustable-speed fan based on the temperature, and adjusts the temperature of the cooling plate. Temperature and heat dissipation efficiency to achieve the control of the humidity inside the incubator.

Specifically, the incubator further includes a controller, and the controller is used to adjust the output voltage of the controller according to the temperature fluctuation in the incubator, so as to adjust the speed of the adjustable-speed fan.

In one embodiment, the description of the specific humidity control function of the carbon dioxide incubator can refer to step S101-step S102.

Those skilled in the art can understand that each module in the carbon dioxide incubator can be split or combined adaptively. Such splitting or merging of specific modules will not cause the technical solution to deviate from the principle of the present invention, therefore, the technical solutions after splitting or merging will all fall within the protection scope of the present invention.

So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings, but those skilled in the art will easily understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims (10)

1. The utility model provides a humidity control method, is applied to carbon dioxide incubator, its characterized in that, carbon dioxide incubator includes heating panel and adjustable speed fan, and wherein adjustable speed fan is through to setting up in the heating panel of incubator body blowing in order to adjust the temperature and the radiating efficiency of heating panel, includes:

acquiring the temperature in the incubator;

and controlling the rotating speed of the adjustable speed fan based on the temperature so as to control the humidity in the incubator.

2. The method of claim 1, wherein controlling the adjustable fan speed based on the temperature to achieve control of humidity within the incubator comprises:

when the temperature does not reach the preset threshold value, the adjustable speed fan works at the maximum rotating speed;

when the temperature reaches a preset threshold value, the speed-adjustable fan adjusts the rotating speed according to the temperature fluctuation degree in the incubator.

3. The method according to claim 2, further comprising obtaining the temperature fluctuation in the incubator by at least the steps of:

taking a preset time length as a period, measuring the temperature value in the incubator for a plurality of times in each period, wherein the time length is equal to the interval between every two measurements;

obtaining an average value of temperatures in the incubator in each period according to the temperature values in the incubator which are measured for multiple times;

averaging the average value of the temperature in each period incubator to obtain a total average value;

and obtaining a variance according to the average value and the total average value of the temperature in the incubator in each period, wherein the value of the variance represents the temperature fluctuation degree in the incubator.

4. The method according to claim 3, wherein the speed adjustment of the adjustable speed fan is achieved by adjusting the output voltage of the controller, and the speed adjustment of the adjustable speed fan is performed according to the temperature fluctuation degree in the incubator, comprising:

according to historical data of regulating the output voltage of the controller and measuring the temperature for multiple times, obtaining a linear relation between the variance and the output voltage of the controller;

and adjusting the output voltage of the controller according to the current variance and the linear relation.

5. The method of claim 1, wherein controlling the adjustable fan speed based on the temperature to achieve control of humidity within the incubator comprises:

controlling the rotating speed of the speed-adjustable fan based on the temperature, and adjusting the temperature and the heat dissipation efficiency of the heat dissipation plate;

when the temperature of the radiating plate is lower than the temperature in the incubator and the area near the radiating plate reaches saturated vapor pressure, the vapor in the area near the radiating plate forms condensation in the area near the radiating plate;

the vapor in the incubator moves to the area near the heat dissipation plate to form a certain amount of condensation to reach temperature and humidity balance, so that the humidity in the incubator is controlled.

6. The method according to claim 5, wherein a heating wire for adjusting the temperature in the incubator is arranged around the incubator body, and the power of the heating wire and the rotation speed of the adjustable speed fan are adjusted to change the corresponding temperature and humidity when the temperature and humidity are balanced.

7. An electronic device comprising a processor and a memory, the memory being adapted to store a plurality of program codes, characterized in that the program codes are adapted to be loaded and executed by the processor to perform the humidity control method of any one of claims 1 to 6.

8. A computer readable storage medium, in which a plurality of program codes are stored, characterized in that the program codes are adapted to be loaded and executed by a processor to perform the humidity control method according to any one of claims 1 to 6.

9. The utility model provides a carbon dioxide incubator, its characterized in that, including incubator body, set up in heating panel, adjustable speed fan, temperature acquisition device, heater strip of incubator body and the electronic equipment of claim 7, wherein temperature acquisition device is used for acquireing incubator internal temperature, the heater strip is used for adjusting incubator internal temperature, adjustable speed fan is based on temperature control adjustable speed fan rotational speed adjusts the temperature and the radiating efficiency of heating panel, in order to realize to the control of incubator internal humidity.

10. The carbon dioxide incubator of claim 9, further comprising a controller configured to adjust the controller output voltage based on temperature fluctuations within the incubator to adjust the rotational speed of the adjustable speed fan.

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