METHOD FOR ACQUIRING PARAMETERS OF DYNAMIC SIGNAL

The application discloses a method for acquiring parameters of a dynamic signal, including: selecting a dynamic sample signal sequence of a power grid to constitute an autocorrelation matrix; determining an effective rank of the autocorrelation matrix and the number of frequency components of the dynamic sample signal sequence; establishing an AR model, and solving a model parameter of the AR model; determining an expression and a complex sequence of the dynamic sample signal sequence by using a Prony algorithm, wherein the dynamic sample signal sequence is represented by the complex sequence with a minimum square error; and substituting a root of a characteristic polynomial corresponding to the model parameter into the complex sequence and solving various parameters of the dynamic sample signal sequence. In the application, with the idea of AR parameter model, a current signal is considered to be a linear combination of signals at previous time points. 1. A method for acquiring parameters of a dynamic signal , comprising:selecting a dynamic sample signal sequence of a power grid, and constituting an autocorrelation matrix by the dynamic sample signal sequence;determining an effective rank of the autocorrelation matrix, and determining the number of frequency components of the dynamic sample signal sequence based on the effective rank;establishing an AR model, and solving a model parameter of the AR model;representing the dynamic sample signal sequence as a set of sinusoidal components of a damping oscillation by using a Prony algorithm;determining a complex sequence of the dynamic sample signal sequence, wherein the dynamic sample signal sequence is represented by the complex sequence with a minimum square error; andsubstituting a root of a characteristic polynomial corresponding to the model parameter into the complex sequence, and solving various parameters of the dynamic sample signal sequence, wherein the various parameters comprises amplitude, phase, ...

INFORMATION SHARING METHOD, SYSTEM AND DEVICE AND COMPUTER STORAGE MEDIUM

An information sharing method, device and system, and a computer storage medium are described. The method includes: a server receiving user information change data and determining information change content; inquiring at least one pre-stored group according to the information change content, determining that a group corresponding to the information change content exists, and obtaining information about a target object of the group; and sending the information change content is sent to the target object.

SHORT CIRCUIT PROTECTION FOR DATA INTERFACE CHARGING

A switching power converter is provided with an overvoltage protection circuit that softly switches on a power bus switch during a soft-start period responsive to a device connecting to a data cable for receiving power over a power bus coupled to the power bus switch. 1. A method , comprising:detecting that a device has connected to data cable including a power bus for receiving power from the power bus;in a power converter, charging an output capacitor to a power supply voltage, the output capacitor being coupled to the power bus through a power bus switch that is off prior to the expiration of a de-bouncing period following the connection of the device to the data cable;softly switching on the power bus switch at a beginning of a soft-start period following the expiration of the de-bouncing period, wherein the power bus switch has a greater resistance while being softly-switched on than when full-switched on; andswitching the power bus switch off during the soft-start period responsive to a determination that the power supply voltage has dropped below a short circuit threshold voltage.2. The method of claim 1 , wherein softly switching on the power bus switch comprises switching on a soft-switch transistor to couple a gate of a power bus switch transistor through a soft-start resistor to a node charged to the power supply voltage.3. The method of claim 2 , further comprising:comparing the power supply voltage to a rise threshold voltage during the soft-start period; andfully switching on the power bus switch transistor responsive to the comparison indicating that the power supply voltage is greater than the rise voltage threshold.4. The method of claim 3 , wherein the data cable is a USB cable.5. The method of claim 4 , wherein the USB cable is a USB type C cable.6. The method of claim 1 , wherein charging the output capacitor to the power supply voltage comprises charging the output capacitor through a second stage of a flyback converter.7. The method of claim 1 ...

Image processing device, image processing method, and non-transitory computer-readable recording medium having stored therein image processing program

An image processing device includes: an acquisition unit that acquires a probability distribution of luminance of a pixel in a plurality of perspective images including the luminance of the pixel which is superposition of luminance components resulting from respective objects, based on an occurrence frequency of a perspective image in which the luminance of the pixel has respective values of a plurality of values; a distribution estimation unit that estimates a mixture distribution indicating the acquired probability distribution; a component estimation unit that estimates a component corresponding to a smallest expectation value distribution of which an expectation value is the smallest among a plurality of partial distributions that form the estimated mixture distribution, and forming at least a portion of the luminance of the pixel; a removal unit that removes the estimated component from the luminance of the pixel included in the perspective image.

Treatment method with iap inhibitor

Improved methods for treating hepatitis B (HB) in patients with (5S,5′S,8S,8′S,10aR,10a′R)-3,3′-(1,3-phenylenedisulfonyl)bis(N-benzhydryl-5-((S)-2-(methylamino)propanamido)-6-oxodecahydropyrrolo[1,2-a][1,5]diazocine-8-carboxamide) (Compound (I)) are disclosed herein. Dosing regimens of Compound (I) for the treatment of HBV infection are provided.

BISDIAZABICYCLO COMPOUND FOR TREATING AND/OR PREVENTING HEPATITIS VIRUS-RELATED DISEASES OR DISORDERS

Disclosed are a bisdiazabicyclo compound for treating and/or preventing hepatitis virus-related diseases or disorders, a method for treating and/or preventing hepatitis virus-related diseases or disorders by using the bisdiazabicyclo compound, and a use of the bisdiazabicyclo compound in the preparation of a drug for treating and/or preventing hepatitis virus-related diseases or disorders, and/or eliminating or mitigating hepatitis virus-related diseases or disorders. 135-. (canceled)36. A method of using a compound for treatment and/or prevention of a disease or disorder associated with a hepatitis virus , wherein the method comprises administering a therapeutically and/or prophylactically effective amount of the compound to a patient having the disease or disorder associated with a hepatitis virus , and the compound is a bisdiazabicyclo compound or a pharmaceutically acceptable salt thereof.50. The method according to claim 36 , wherein the disease or disorder associated with hepatitis virus is a disease or disorder associated with hepatitis A virus claim 36 , hepatitis B virus or hepatitis C virus.51. The method according to claim 36 , wherein the disease or disorder associated with hepatitis A claim 36 , hepatitis B claim 36 , hepatitis C claim 36 , and liver cirrhosis.52. The method according to claim 36 , wherein the compound treats and/or prevents the disease or disorder associated with hepatitis virus by modulating an immune response.53. The method according to claim 36 , wherein the method comprises using the compound in combination with a drug known to treat HBV. This application is a continuation of U.S. application Ser. No. 16/624,050, filed on Dec. 18, 2019, which is the U.S. national stage application of PCT International Application No. PCT/CN2018/116289, filed on Nov. 20, 2018, which claims the benefit of foreign priority of Chinese Patent Application No. 201711193388.1, filed on Nov. 24, 2017. The entire contents of the aforementioned applications ...

Method for On-Line Diagnosing Gradually-Changing Fault of Electronic Current Transformers

A method for on-line diagnosing gradually-changing fault of electronic current transformers comprises the following steps collecting output signals of electronic transformers of a whole transformer substation, calculating theoretical instantaneous values of the current at the tail ends of power transmission lines and on secondary sides of transformers at every moment, comparing the theoretical instantaneous values with the corresponding collected values, calculating residual errors of the electronic current transformers at the head and tail ends of each power transmission line and the primary and the secondary sides of each transformer respectively, judging whether gradually-changing fault occurs with the electronic current transformers by comparing the residual errors with preset threshold values, and simultaneously performing Kirchhoff detection by injecting current into a busbar to position a fault transformer. 1. A gradual failure online diagnosis method for an electronic current transformer , comprising:collecting, at the head of each transmission line of a substation, three-phase current instantaneous signals output by an electronic current transformer and three-phase voltage instantaneous signals output by an electronic voltage transformer;{'sub': 'out', 'computing theoretical three-phase current instantaneous values i(t) at the end of the transmission line based on the three-phase current instantaneous signals and the three-phase voltage instantaneous signals that are collected at the head of the transmission line;'}{'sub': 'n', 'collecting three-phase current instantaneous signals i(t) output by an electronic current transformer at the end of each transmission line;'}{'sub': a', 'n', 'out', 'a, 'computing a first residual ε=|i(t)−i(t)| between the current transformer at the head of the transmission line and the current transformer at the end of the transmission line based on the three-phase current instantaneous signals collected at the end of the ...

Portable electronic device

Embodiments of a portable electronic device are disclosed, the portable electronic device includes a housing, a hollow sleeve, a speaker assembly, and a keyboard module. The hollow sleeve is pivoted on the housing. The speaker assembly is movably disposed in the hollow sleeve. The keyboard module is movably disposed on the outer surface of the hollow sleeve. Through adjusting the position of the speaker assembly and the keyboard module relative to the housing, the usability of the portable electronic device is improved.

Sense resistor fault detection

A power system and related methods provide sense resistor fault detection and safe operation of switching power converters and connected devices such as portable electronic devices powered by the switching power converter. The power system detects an open circuit or short circuit condition of the sense resistor and controls output current of the switching power converter to ensure safe operating conditions of the power system and connected equipment. The power system can also detect initial inrush current of the connected equipment and detect a duty cycle of the switching power converter to positively detect a short circuit condition of the sense resistor.

METHOD FOR PRODUCING AN OPTICALLY ACTIVE PHOSPHINE

Process for producing optically active carboxylic acids and chiral ligands for this purpose

A process for the production of an optically active carboxylic acid (I), which comprises subjecting an olefinic carboxylic acid (II) to asymmetric hydrogenation using a complex as a catalyst consisting of an optically active phosphine (III) and a ruthenium compound. complex of with ruthenium compound According to the process of the present invention, optically active carboxylic acids can be produced with high yield. The compounds of formula (III) are also claimed.

A shock-resistant drill chunk of hand tightening type

A shock-resistant drill chunk of hand tightening type is disclosed, which comprises a rear cap, a body, a thrust ring, a ball supporting ring, balls, a threaded ring, clamping jaws, a front cap, and an end cap. The ball supporting ring is secured in body adjacent to the thrust ring, and 4-24 cylindrical through-holes are arranged at the end face of the ball supporting ring, a ball can spin freely in each cylindrical through-holes. The threaded ring located in the second middle groove of the body has a sloping ball-race surface facing the ball. During the end phase of the clamping process, the balls move radially along the sloping ball-race surface and abut against an inner wall of the cylindrical through-holes, so that a frictional force is produced between the balls and the inner wall of the cylindrical through-holes to prevent the ball from rotating. Therefore the reverse rotate of the threaded ring is suppressed and the loose of the tool under big shock is prevented.

A composition for treatment of diabetes mellitus and a preparation and an use thereof

The present invention relates to a composition for treating diabetes and a preparation method thereof as well as use thereof. The present invention provides a composition for treating diabetes, comprising the following active components based on the parts by weight: 10-100 parts of Pumpkin powder; 6-200 parts of spirulina; and 2-90 parts of Lychee Seed. The invention further provides the preparation method of the composition and the use of the medicament for treating diabetes. By taking the composition, the blood sugar concentration of diabetics can be effectively controlled, the complicating diseases of diabetics can be avoided, and the health of diabetics can be protected.

Production procedure of an optically active beta-amino acid

Un procedimiento de producción de un ß-aminoácido ópticamente activo de fórmula (2), **Fórmula** en la que b es 0 o 1; el símbolo * denota que el átomo de carbono es un carbono quiral; R1 es un átomo de hidrógeno, un grupo alquilo, un grupo alquilo sustituido, un grupo cicloalquilo, un grupo cicloalquilo sustituido, un grupo aralquilo, un grupo aralquilo sustituido, un grupo arilo, un grupo arilo sustituido, un grupo heterocíclico alifático, un grupo heterocíclico alifático sustituido, un grupo heterocíclico aromático, un grupo heterocíclico aromático sustituido, un grupo alcoxi, un grupo alcoxi sustituido, un grupo aralquiloxi, un grupo aralquiloxi sustituido, un grupo ariloxi o un grupo ariloxi sustituido; R2 es un átomo de hidrógeno, un grupo alquilo, un grupo alquilo sustituido, un grupo cicloalquilo, un grupo cicloalquilo sustituido, un grupo aralquilo, un grupo aralquilo sustituido, un grupo arilo, un grupo arilo sustituido, un grupo heterocíclico alifático, un grupo heterocíclico alifático sustituido, un grupo heterocíclico aromático, un grupo heterocíclico aromático sustituido, un grupo alcoxi, un grupo alcoxi sustituido, un grupo aralquiloxi, un grupo aralquiloxi sustituido, un grupo ariloxi, un grupo ariloxi sustituido, un grupo alquiloxicarbonilo o un grupo aralquiloxicarbonilo; R3 es un grupo alcoxi, un grupo alcoxi sustituido, un grupo aralquiloxi, un grupo aralquiloxi sustituido, un grupo ariloxi, un grupo ariloxi sustituido, un grupo amino o un grupo amino sustituido, X' es un ácido, y R1 y R2 o R2 y R3 pueden estar combinados conjuntamente para formar un anillo con la condición de que R1 y R2 no sean un átomo de hidrógeno simultáneamente, que comprende someter una enamina de fórmula (1) **Fórmula** en la que R1, R2, R3 y X' tienen los mismos significados que los descritos anteriormente, y a es 0 o 1, a una hidrogenación asimétrica, en el que la hidrogenación asimétrica se lleva a cabo en presencia de un catalizador para la hidrogenación asimé ...

Plasma igniter with assembled cathode

This invention relates to a plasma igniter for directly igniting the coal-powder furnace. Said plasma igniter consists of a plasma generator which includes a composite anode, an assembled cathode, an electromagnetic coil and a transmitting coil; a coal powder burner which comprises mutt-stage pipes for conveying igniting coal, an equipment for adjusting thickness of coal powder and a four-stage burner canister; and a generator brace. Said assembled cathode consists of a cathode plate, a fixation nut, a conductive pipe, a inflooding pipe, a inflooding guiding pipe, a cathode lid and a sealing spacer. The lining for generatoring electric arc is assembled with the front of cathode. An alloy plate is used as the cathode plate. The nozzle that used for cooling the cathode is first convergent and then expansive, and is placed in the middle of the conductive pipe. The plasma igniter has the advantage of stableburning. It can be used as not only a main burner for the boiler but also a igniting burner. Since oil is not used, lots of petroleum source is saved.

A shock-resistant drill chuck of hand tightening type

Handwriting input processing device and method

The present invention discloses a handwriting input processing device and method. The method comprises: determining time efficiency and space efficiency for sampling coordinate points on a touch screen according to the prestored configuration parameters; determining a time interval between strokes and a time interval between words of user writing according to the configuration parameters, and sampling and identifying user operations on the touch screen according to the determined time interval between strokes, time interval between words, time efficiency, and space efficiency.

Process for the preparation of optically active carboxylic acids and chiral ligants therefor

Method for producing an optically active beta-amino acid

The Problem to Be Solved: To provide a producing method of an optically active β-amino acid useful as intermediate for the production of medicines, agricultural chemicals and physiologically active substances, by means of a catalytic and asymmetric synthesis method of high performance and a high enantiomeric excess, without requiring additional procedures such as introduction and removal of protecting group and so on. Means to Solve the Problems: A producing method of an optically active β-amino acids which comprises subjecting an enamine to an asymmetric hydrogenation.

Bisdiazabicyclo compound for treating and/or preventing hepatitis virus-related diseases or disorders

Disclosed are a bisdiazabicyclo compound for treating and/or preventing hepatitis virus-related diseases or disorders, a method for treating and/or preventing hepatitis virus-related diseases or disorders by using the bisdiazabicyclo compound, and a use of the bisdiazabicyclo compound in the preparation of a drug for treating and/or preventing hepatitis virus-related diseases or disorders, and/or eliminating or mitigating hepatitis virus-related diseases or disorders.

Bisdiazabicyclo compound for treatment and/or prevention of hepatitis virus-related diseases or disorders

Disclosed are a bisdiazabicyclo compound for treating and/or preventing hepatitis virus-related diseases or disorders, a method for treating and/or preventing hepatitis virus-related diseases or disorders by using the bisdiazabicyclo compound, and a use of the bisdiazabicyclo compound in the preparation of a drug for treating and/or preventing hepatitis virus-related diseases or disorders, and/or eliminating or mitigating hepatitis virus-related diseases or disorders.

Bisdiazabicyclo compound for treatment and/or prevention of hepatitis virus-related diseases or disorders

Disclosed are a bisdiazabicyclo compound for treating and/or preventing hepatitis virus-related diseases or disorders, a method for treating and/or preventing hepatitis virus-related diseases or disorders by using the bisdiazabicyclo compound, and a use of the bisdiazabicyclo compound in the preparation of a drug for treating and/or preventing hepatitis virus-related diseases or disorders, and/or eliminating or mitigating hepatitis virus-related diseases or disorders.

A plasma ignition burner

Spandex maximum draft ratio tester

一种氨纶最大牵伸比测试仪，包括底座、安装支架、退绕单元、搭接单元、断丝感应单元、加速罗拉、转速感应器、分丝单元、收线罗拉、第二转动驱动装置、与第二转动驱动装置、转速感应器及断丝感应单元均连接的控制器；断丝感应单元包括设置于底座内部的气缸安装板、安装于气缸安装板上且位于底座内部的升降气缸、底面与升降气缸的输出轴连接的升降板、若干垂直连接于升降板的顶面上的安装块及安装于安装块上的断丝感应器。如此能够实现自动判断氨纶丝断裂、自动读取氨纶丝断裂时的转速、自动计算最大牵伸比。

Long-distance rock pipe jacking machine

本实用新型提出一种长距离岩石顶管机，包括壳体、刀盘、滚刀、刮刀、刀盘牛腿、锥筒破碎条、岩石破碎仓、摄像头、刀盘驱动系统、液压阀组、机内液压站、泥水阀组和纠偏装置，滚刀通过滚刀箱后置在刀盘上，刀盘牛腿和锥筒破碎条设置在岩石破碎仓中，锥筒破碎条环绕在刀盘牛腿的外侧，锥筒破碎条的后侧设置有水套，机头外壳的内部设置有回转支承传动系统和前置泥水循环系统，回转支撑传动系统包括中空的传动轴和前后仓门，前置泥水循环系统包括送水管和水套，水套的套壁上设置有冲水喷口。本实用新型便于工人进行检查和更换刀具，而且壳体管壁的阻力小，推进距离长，工作效率高，施工成本和风险低，并且设计合理、结构简单，适合大规模推广。

Switching power converter with secondary-side control

A flyback converter with secondary-side control includes a secondary-side controller configured to emulate a primary-winding current. Based upon the emulated primary-winding current, the secondary-side controller signals a primary-side controller through at least one isolation capacitor to switch off a power switch transistor.

Preparation method of strong-flavor blueberry red wine

Treatment method with iap inhibitor

Manual and sensor integrated kitchen tap and control method

Disclosed in the present invention is a manual and sensor integrated kitchen tap, comprising a valve seat, a water output nozzle and an infrared sensor, wherein the valve seat is provided with a cold water inlet and a hot water inlet; a manual water output temperature-adjusting valve core and a sensor water output temperature-adjusting valve core are mounted on the valve seat; a manual water output hole and a sensor water output hole are provided in the valve seat; the manual water output temperature-adjusting valve core mixes water discharged through the cold water inlet and the hot water inlet and then outputs same to the manual water output hole; the sensor water output temperature-adjusting valve core mixes water discharged through the cold water inlet and the hot water inlet and then outputs same to the sensor water output hole; the manual water output hole and the sensor water output hole respectively communicate with the water output nozzle; an electromagnetic valve is further provided between the sensor water output hole and the water output nozzle; and the infrared sensor receives a signal and controls the electromagnetic valve to act. The present invention has a compact structure, can achieve manual water output and automatic sensor water output, and further has a temperature adjustment function and good use effects.

Switching power converter with secondary-side control

A flyback converter with secondary-side control includes a secondary-side controller configured to emulate a primary-winding current. Based upon the emulated primary-winding current, the secondary-side controller signals a primary-side controller through at least one isolation capacitor to switch off a power switch transistor.

Cytosine analog as well as preparation method and application thereof

Separation method of special yeasts for blueberry wine fermentation

具有砝码保护功能的纱线耐磨测试仪

一种具有砝码保护功能的纱线耐磨测试仪，包括支架、转动设置于支架上的偏心接线单元、转动驱动单元、转动设置于支架上的若干第一转向辊及砝码；支架包括底座及与底座垂直连接的安装盒；若干第一转向辊包括第一辊、第二辊及第三辊，其中，第二辊位于第一辊与第三辊之间且第二辊距离底座的高度小于第一辊或第三辊距离底座的高度；纱线的第一端与偏心接线单元固定连接，第二端依次绕过第一辊、第二辊及第三辊并与砝码连接；在底座上且于第三辊的下方设置有一中空且圆柱形的砝码座，砝码座的内径大于砝码的直径，砝码座的底部设置有缓冲垫。如此可避免纱线断裂时砝码与底座刚性接触而对底座及底座中的部件造成撞击伤害、提高安全及可靠性。

Electrode sheet slotting method and device

The present disclosure discloses a method and device for forming a groove on an electrode plate. The method for forming a groove on an electrode plate includes: thinning an active material layer by a laser method, where the active material layer is located in a to-be-grooved area of the electrode plate; and removing the thinned active material layer by a physical removal method to form an accommodating groove that exposes the current collector layer. By adopting a combination of the laser method and the physical removal method, the present disclosure, the present disclosure, on the one hand, can quickly remove the active material layer in the to-be-grooved area, and on the other hand, can avoid damaging the current collector layer. This ensures the processing precision, speeds up the production and improves the product yield.

Method and device for forming groove on electrode plate

The present disclosure discloses a method and device for forming a groove on an electrode plate. The method for forming a groove on an electrode plate includes: thinning an active material layer by a laser method, where the active material layer is located in a to-be-grooved area of the electrode plate; and removing the thinned active material layer by a physical removal method to form an accommodating groove that exposes the current collector layer. By adopting a combination of the laser method and the physical removal method, the present disclosure, the present disclosure, on the one hand, can quickly remove the active material layer in the to-be-grooved area, and on the other hand, can avoid damaging the current collector layer. This ensures the processing precision, speeds up the production and improves the product yield.

Highly efficient tannin-degrading bacterium sl006 from rosa roxburghii and application thereof

A strain of highly efficient tannin-degrading bacterium SL006 from Rosa roxburghii and application thereof are disclosed in the present application, belonging to the technical field of biotechnology. The highly efficient tannin-degrading bacterium SL006 from Rosa roxburghii has a taxonomic designation of Penicillium adametzioides, and has been preserved in the China Center for Type Culture Collection (CCTCC), with a preservation number of CCTCC NO:M 20221946. The highly efficient tannin-degrading bacterium SL006 with high tannin degradation efficiency is separated, purified and screened from moldy Rosa roxburghii pomace.

A method for producing blueberry brandy based on secondary fermentation of blueberry pomace

Information sharing method, system and device and computer storage medium

Appareil pour capturer les animaux nuisibles et procédé de fabrication correspondant

一种新型高效的多通阀

本实用新型提出一种新型高效的多通阀，包括阀体，所述阀体的内部设置有阀芯，所述阀芯的顶部设置有阀杆，所述阀体的顶部设置有阀盖和压盖，所述阀盖的上方设置有旋转手柄，所述旋转手柄与阀杆连接，所述阀体的形状为圆筒形，所述阀体的底部设置有底盘，所述底盘为平面封闭结构，所述阀体的侧面设置有多个位于不同角度、不同高度的法兰接口，所述阀芯为空心结构且形状为圆筒形，所述阀芯的侧面至少设置有两个位于不同角度、不同高度的阀口。本实用新型设计合理、结构简单，体积小，可以适用于一进多出的管路系统中，空间利用率高，输送效率高且成本低，适合大规模推广。

Electrode sheet slotting method and device

Information sharing method, system and device, and computer storage medium

Backlight control circuit capable of distinguishin

Hand-Up Initiating and Responding Method and Interactive System in Multi-Party Video Activity

A hand-up initiating and responding method and interactive system in a multi-party video activity are disclosed. The hand-up initiating method in a multi-party video activity includes: step 1) pressing a hand-up button, sending a hand-up message, and updating a hand-up status in a local video window and hand-up statuses in a local roster; step 2) releasing the hand-up button, and starting countdown; step 3) sending a hand-up cancellation message and updating the hand-up status in the local video window and the hand-up statuses in the local roster at the end of the countdown; and step 4) if the hand-up button is pressed again within the countdown time, skipping to step 2) without sending a hand-up message. The present invention provides a special interactive mode, in which when a participant raises a question, an initiator can perceive in real time and respond in time.

Device and method for accurately monitoring angle of ranging arm of coal mining machine

The present invention relates to an apparatus and method for accurately monitoring an angle of an arm of a coal mining shearer. The apparatus for accurately monitoring the angle includes an arm pulley, a machine body pulley, a synchronous belt, a fixed 5 shaft and a rotation angle sensor, where the arm pulley is mounted on the arm of the coal mining shearer; a rotation central axis of the arm pulley is coaxial with a swing center line of the arm; the fixed shaft is mounted on a coal mining shearer body; the machine body pulley is rotationally supported on the fixed shaft; the rotation angle sensor is coaxially mounted relative to the machine body pulley; a diameter of the arm 10 pulley is larger than that of the machine body pulley; and the synchronous belt is wrapped around the arm pulley and the machine body pulley, so that the arm pulley and the machine body pulley rotate at a same linear speed. The method for accurately monitoring the angle implements monitoring by using the apparatus for accurately monitoring the angle. The present invention can solve the problems of low mining 15 height detection accuracy and poor reliability of the coal mining shearer. 9

Portable electronic device

Embodiments of a portable electronic device are disclosed, the portable electronic device includes a housing, a hollow sleeve, a speaker assembly, and a keyboard module. The hollow sleeve is pivoted on the housing. The speaker assembly is movably disposed in the hollow sleeve. The keyboard module is movably disposed on the outer surface of the hollow sleeve. Through adjusting the position of the speaker assembly and the keyboard module relative to the housing, the usability of the portable electronic device is improved.