117results about How to "Low synchronization requirement" patented technology

The invention relates to a speaker clustering method for a distributed microphone, which comprises the following steps: firstly performing pretreatment on signals acquired by the distributed microphone, further adopting the time delay estimation method for calculation against sound source signal fragments, getting a corresponding time delay estimation vector, then ruling out wrong data, performing speaker segmentation, and finally performing speaker clustering according to the speaker segmentation result. The distributed microphone is used as a signal acquisition and output device for calculating the time delay vector of the voice signal fragments, the time delay estimation precision is improved by ruling out the wrong data, and clustering algorithm is adopted for the time delay vector so as to respectively classify the voice signal fragments according to identities of speakers; furthermore, the device has the advantages of low price and convenience in use, and the speaker clustering method can be applied in a multi-person multi-party dialogue scene under a complex acoustic environment.

The invention discloses an acoustic source spatial positioning method for a distributed asynchronous acoustic sensor. The method comprises the following steps of: calculating a spatial coordinate under an assumed condition; transmitting a correcting signal to calculate a structure of the distributed asynchronous acoustic sensor; preprocessing the signal acquired by the distributed asynchronous acoustic sensor; calculating an acoustic source signal by a time delay estimation method to acquire a corresponding time delay estimated value; and finally calculating a spatial position coordinate of each acoustic source according to the time delay estimated value. The acoustic sensor is arranged and spaced without any limitation, signals acquired by the acoustic sensor are incompletely synchronousin a time domain, and the method has the advantages of low cost, convenience of use and the like and can be applied to a multi-person multi-party dialogue scene under a complex acoustic environment.

The invention discloses a method for detecting a fault of a power transmission line based on a random matrix, and the method comprises the steps: respectively obtaining three-phase currents of n sample values at two ends of the line, calculating and obtaining a sequences of positive sequence current fault components, negative sequence components and zero sequence components; respectively performing copying and translation processing of each sequence, and carrying out the expansion to form a matrix of each sequence, and then performing the superimposition of a noise matrix to form an original random matrix of each sequence; employing the random matrix theory for transforming the original random matrixes into a standard matrix product; calculating a complex eigenvalue of the standard matrixproduct, calculating and obtaining the average spectral radius of the current component sequence of the line according to the eigenvalue; constructing two criteria for fault detection of the power transmission line, determining a threshold value, and determining that the line whose average spectral radius is less than the threshold value as a faulty line. The method can accurately detect the faulty line, is not affected by the position of the fault point, the fault type, a system operation mode, power flow shift and the system oscillation, can identify a high-resistance ground fault, and has better resistance to abnormal data.

The invention discloses a train axle temperature sensor fault detection method and an apparatus. The method comprises the following steps that in a normal operating condition of an axle temperature sensor, training data of the axle temperature sensor is acquired; pretreatment is performed on the training data so that time of the training data is synchronous and the training data is low-noise and smooth and steady; according to the training data, a principal component analysis method is used to establish a principal component model and generate a square prediction error control limit; real-time monitoring is performed and measurement data of the axle temperature sensor is acquired; pretreatment is performed on the measurement data; according to the measurement data, the principal component analysis method is used to generate square prediction error statistics; whether the square prediction error statistics is less than or equal to the square prediction error control limit is determined; if the square prediction error statistics is less than or equal to the square prediction error control limit, the axle temperature sensor works normally; if the square prediction error statistics is greater than the square prediction error control limit, the axle temperature sensor has a fault and fault alarm is performed. By using the method and the apparatus of the invention, a data state of the sensor is detected in real time; a hidden trouble is found out timely and the fault sensor is detected so that axle temperature data collected in a normal state is guaranteed to be reliable.

The invention relates to the technical field of signal transmission, and discloses a frequency division multiple access method of a variable-bandwidth FMT (frequency modulated transmitter) based on single-carrier transmission. The frequency division multiple access method comprises the following steps: S1. different users transmit variable-bandwidth subcarrier signals synchronously at the transmitting end, wherein the subcarrier signals are obtained through filtering of original data to be transmitted by the users; and S2. the signals sent from different users are received in parallel at the receiving end. In the frequency division multiple access method disclosed by the invention, (1) the bandwidth of subcarriers transmitted by each user is variable (subcarriers of different bandwidth have different resistance to time selective fading and frequency selective fading), and the bandwidth of the subcarriers needs to meet a certain condition; (2) the variable-bandwidth subcarriers are filtered single-carrier signals; and (3) a transmitter transmits data synchronously, and the data is demodulated in parallel by a receiver, thus the realizing complexity of the transmitter and the receiver is reduced, the requirement of the system on synchronization and the peak-to-average power ratio of the system are reduced, and the resource allocation efficiency is improved simultaneously.

The invention relates to a track step driller mover, wherein it is formed by translate guider and lifter; the translate guider is formed by two tracks (1), guide block (2), and translate cylinder (3); two tracks (1) via front connecting beam (4), support rod (5), and back connecting beam (6) are fixed together; the guide block (2) can slide on the tracks (1), to connect the base of object (7); two ends of translate cylinder (4) are hinged to the base of object (7) and front connecting beam (4); the lifting cylinder (8) of lifter is fixed on the fixed base (9); the piston via pin (11) is connected to the beam (10); the beam (10) is fixed on the base of object (7). The length of track will not be affected by the base structure of object. And it uses long track and translate cylinder with long strike, to reduce the cost, only with two translate cylinders.

A wide area backup protection method based on a fault voltage ratio and a multi-information fusion provided by the invention comprises the following steps: (1) detecting a fault area of wide area protection; (2) obtaining a fault probability of a line according to the fault voltage ratio; (3) obtaining a fault probability of the line according to the multi-information fusion method; and (4) obtaining a synthetical fault probability of the line through weighting and synthesizing the fault probability in the step (2) and the fault probability in the step (3). According to the invention, the wide area protection is able to have a good motion performance in complex conditions, with a high fault tolerance.

The invention belongs to the field of intelligent transformer substations, and particularly relates to a station domain backup protection method for an intelligent transformer substation. The stationdomain backup protection method includes: obtaining the voltage and current sampling values acquired by merging units in the station through an SV network in a transformer substation process layer; acquiring position information of circuit breakers in the station and action information of all the main protections through a GOOSE network in the process layer; and acquiring the circuit breaker position information of a line-to-end substation, the main protection action information, and the action information of opposite terminal station domain backup protection through inter-station data channels. The invention is scientific and reasonable, and has a high speed, high sensitivity and high reliability.

The invention discloses an indoor mobile phone positioning method based on TDOA (Time difference of Arrival). Sound wave beacons and wireless beacons are transmitted and received through utilization of a microphone and a wireless network card built in a smart phone; distance measurement and positioning are carried out according to the time difference of transmission of the wireless signals and the sound wave signals; positioning base stations periodically transmit and broadcast the sound wave beacons and the wireless beacons and record transmitting time stamps of the signals through a drive layer; a positioning mobile phone receives the wireless beacons and the sound wave beacons of the nearby positioning base stations and records the arrival time stamps of the beacons through the drive layer; on the basis of the four time stamps, the positioning mobile phone can calculate the distance to the positioning base stations; frequency modulation is carried out on the sound wave beacons based on an MAC address; the modulation method can be used for identifying source addresses of the beacons; and the positioning mobile phone can calculate own position coordinate through adoption of a maximum likelihood method when measuring the arrival distance of the three positioning base stations. The method is independent of special hardware, time synchronization does not need to be carried out between system nodes, and the method has the advantages of simplicity, feasibility, high positioning precision and high stability.

The present invention relates to a translational vulcanizer, including a translational mechanism, a translational frame, an upper vulcanizing chamber, a lower vulcanizing chamber, a device for assembling and disassembling a tyre, a radial parting mould, a stand body, a second stand, a switching mould oil cylinder and a translational oil cylinder. The translational frame and the switching mould oil cylinder are arranged on the translational mechanism, the upper vulcanizing chamber is arranged on a piston rod of the switching mould oil cylinder, the lower vulcanizing chamber is arranged on the stand body, and the device for assembling and disassembling the tyre is arranged on the second stand. The radial parting mould is divided into an upper mould and a lower mould, the lower mould is arranged in the lower vulcanizing chamber, and the upper mould is fixed below the upper vulcanizing chamber. Left and right supports of the translational mechanism are provided with three to five wheeled kinematic mechanisms locating below the support separately, and each wheeled kinematic mechanism is arranged on a wheeled guide rail fixed on the supports locating on the right and left sides of a stand component. the vulcanizer is used for vulcanizing a giant engineering tyre, has a stable and smooth operation by employing the wheeled kinematic mechanism, is not easy to break a movable member, reduces the cost and time for maintenance, and has a long service life.

The invention belongs to a method for locating indoor wireless propagated signal source, comprising the following steps of: adopting a database-setting signal source to set up a location database, defining a frequency domain amplitude response parameter between each receiver and each target, and defining the position of the targets which are to be located. Because the invention adopts a signal with the shape of normalized gammagram as a database-setting signal to define a normalized frequency domain amplitude response parameter of wireless propagation channel between each node and each receiver, define a first location parameter corresponding thereto and the database for setting up location, and locate the targets which are to be located, and uses the space difference of multipath propagation and indirect wave propagation between the targets which are to be located and each signal receiver in the location method to conquer negative effects, the invention has the advantages that the sensitivity to position difference in location area can be effectively improved, time synchronicity demand and location cost can be reduced, as well as location accuracy and location precision can be promoted, etc.

The invention discloses a tracked and wheeled switchable traveling chassis. The tracked and wheeled switchable traveling chassis comprises a travelling crane frame, a power system, a control system, travelling wheel groups and two tracks, wherein the power system, the control system, the travelling wheel groups and the two tracks are mounted on the travelling crane frame; the travelling wheel groups and the tracks are respectively arranged at the two sides of the travelling crane frame, the power system is connected with the travelling wheel groups and the tracks respectively, and the control system is connected with the power system. According to the tracked and wheeled switchable traveling chassis disclosed by the invention, the quick switchover of two traveling manners, namely the travelling wheel groups and the tracks, is realized, and the shortcomings and deficiencies of the existing wheeled and tracked traveling mechanisms are overcome; the wheeled moving manner is selected when a vehicle travels on a flat road for a long distance, so that the moving speed can be increased, and the fuel consumption can be lowered; the tracked moving manner is selected when the vehicle travels on special grounds, so that the passing performance of the vehicle can be improved.

A system for a two dimension bar code for synchronous omni-directional information and its identifying method are disclosed with advantages of simple in identifying, low requirement on scanner synchronization and high in ability to identifying with anti-aberration. The system for the two dimension bar code is composed of units aligned in a matrix form and comprises a pair of vertical synchronous information units at two opposing borders in said matrix; a pair of horizontal synchronous information units at another two opposing border in said matrix; a directing information unit having a characteristic shape and / or optic characteristics for identifying a scanning direction and having a specific relative positional relationship between said vertical information synchronous units and horizontal information synchronous units; and a coding information unit inside said matrix, wherein the base of each unit is in the vicinity of the intersection of the central linking line of a pair of the vertical synchronous information units and the central linking line of a pair of horizontal synchronous information units.

The invention discloses a post-processing system for phase polarization joint modulation QKD. The system comprises a sender and a receiver. Each of the sender and the receiver comprises an informationinteraction unit, a parameter estimation unit, an error correction unit and a confidentiality amplification unit which are connected in sequence. The information interaction unit, the parameter estimation unit, the error correction unit and the confidentiality amplification unit of the sender are respectively connected with the information interaction unit, the parameter estimation unit, the error correction unit and the confidentiality amplification unit of the receiver in a one-to-one correspondence manner through channels. According to the invention, aiming at the characteristics of a phase polarization joint modulation QKD system and a double-speed protocol used by the phase polarization joint modulation QKD system, a traditional transceiver base vector comparison step is not needed in the information interaction unit, so that the information interaction amount is reduced, and the post-processing efficiency is improved; and the parameter estimation unit estimates the bit error rate of the key by using a packet parity check method, and selects a reasonable error correction method and a secrecy amplification method after estimating channel parameters, so that the correctness andthe safety of quantum key distribution are improved by the steps.

The invention discloses a signal generation method of a low-interference multispeed multi-cell quasi-synchronous code division multiple access (CDMA) communication system. The method comprises the steps: a spread spectrum sequence code group is an Hadamard matrix set with certain idealized characteristics formed by Bent functions and a Walsh-Hadamard orthogonal sequence set; a sequence set with the characteristic of a similar zero correlation zone (ZCZ) sequence is obtained by calculating with a pair of complementary sequence sets by utilizing the Hadamard matrix set; and a plurality groups of sequence sets with the similar ZCZ sequence characteristics are obtained by carrying out Cartesian convolution operation with the orthogonal sequence set by utilizing the similar ZCZ sequence set. When a system maximum synchronization error and a channel maximum multipath delay spread are in the stated range, the system interference can be reduced greatly. The parameters of the spread spectrum sequence code group and the system efficiency can be adjusted and flexibly selected according to the practical factors. Therefore, the requirements of power control and synchronization by the CDMA communication system are reduced, and the complexity of system realization is lowered.

The invention relates to a cross-layer wireless sensor network MAC protocol communication method and system and belongs to the technical field of wireless sensor networks. A network is divided into zones of different classes according to different skip distances between nodes and SINK nodes. A working manner that periodic scheduling is performed on nodes in all regions is adopted and each period is divided into a periodic data receiving time frame, a periodic data transmitting time frame and a periodic sleep time frame. Periodic scheduling of nodes of adjacent zones is set in a staggered mode and data are transmitted to nodes at the low class until the SINK nodes. The requirement for synchronization of the network nodes is lowered and waiting time delay of data transmission of each skip is reduced. The class of the nodes is used for selecting receiving nodes in the data transmission process and an MAC and a router of data transmission are combined together. Thus, support of an upper-layer routing protocol is not needed, control expenses are reduced and the cross-layer wireless sensor network MAC protocol communication method and system are easy to achieve.

The invention discloses a compound mode solid pulse source. The compound mode solid pulse source comprises a power system, a control system, a signal conversion system and a high-voltage formation system. The high-voltage formation system comprises multiple levels; each level comprises a Marx circuit and a LTD circuit. The Marx circuit is connected with a power source. A control signal which is input through the signal conversion system drives the Marx circuit and the LTD circuit. The LTD circuit is equivalent to a transformer. At the same level, the output end of the Marx circuit is connected with the primary side of the LTD circuit; and the secondary side of the LTD circuit at each level is connected in series and in sequence. By combining the respective advantages of the Marx circuit and the LTD circuit, relatively good balance can be achieved in the aspects of the voltage and current of the output pulse, and the application range of the compound mode solid pulse source is enabled to become wider. According to the pulse source, a relatively low power supply voltage can be adopted, and a relatively high output voltage peak value can be obtained after the voltage superposition of the Marx circuit and the LTD circuit. Through a flexible drive control mode, functions such as an output amplitude adjustment, a repeated frequency adjustment, output pulse width adjustment and output waveform adjustment also can be realized.

The invention provides a distributed power supply-containing petal-type urban power grid regional backup protection method, and the method comprises the steps: enabling two ends of each line on a petal-type urban power grid trunk line to be provided with a protection device and a circuit breaker, and enabling each petal-type looped network trunk line to be provided with an even number of protection devices; setting each petal of the petal type urban power grid as an area, and setting an information processing center at each transformer substation; when a three-phase earth fault occurs on a trunk line of a petal type urban power grid containing a plurality of distributed power supplies, determining a fault section or a fault line step by step according to a comparison result of amplitudes of currents flowing through protections on two sides of a grid-connected point of the distributed power supplies; in the prior art, secondary equipment current transformers in a petal type urban powergrid are broken, so that the current at the current transformers cannot be obtained, maloperation or refusal of a protection device is possibly caused, heavy losses are further caused, and different countermeasures should be taken for the broken current transformers at different positions according to the situation.

The invention relates to a petal type urban power grid grounding fault accurate positioning method based on multi-line zero-sequence current information. Single-phase and two-phase earth fault characteristic analysis is carried out on a petal type urban power grid, and a foundation is laid for simply and effectively realizing accurate positioning of a fault position by utilizing a zero-sequence current association relationship presented by connecting two ends of a trunk line of a single petal ring network to the same bus. Accurate grounding fault positioning can be realized only after the centralized information processing center receives the zero-sequence current steady-state values of the protections on the trunk line, a traveling wave measuring device and the like are not required to beadditionally arranged; and the method has the characteristics of low required communication traffic, low requirement on information synchronism and the like and is reliable in performance, simple andeasy to implement.

The invention discloses a method for generating ultra-wideband optical radiation based on a chirp pulse optical parametric oscillator. The method includes as the steps of: determining pump light of acorresponding wave band and corresponding second-order nonlinear crystal according to the wavelength of required ultra-wideband optical radiation; determining the length of the second-order nonlinearcrystal according to the bandwidth of the required ultra-wideband optical radiation, and determining the pulse width of the pump light according to the second-order nonlinear crystal; designing a third-order nonlinear optical parametric oscillator (OPO) to ensure the existence of self-phase modulation (SPM) in the OPO cavity, so as to obtain the spectral broadening. By introducing enough third-order nonlinear effect into the resonant cavity to make the optical parametric oscillator work in the mode of chirped pulse, and precisely controlling the intracavity net dispersion through a dispersionadjusting element in the cavity, the optical parametric oscillator outputs ultra-wideband optical radiation close to the second-order nonlinear crystal phase matching bandwidth.

The invention discloses a method for generating a signal for an interference-free quasi-synchronous CDMA communication system, comprising the following steps: a spectrum spreading sequence encode block is a similarly generalized double displacement orthogonal sequence set generated by a Z-complementation sequence set and an orthogonal sequence set; the number of the sequences and the lengths of the sequences are increased by the operation of the Walsh-Hadamard extension; and a zero related area is realized by the related operations such as removing the odd displacement. When the maximum synchronous error of the system and the maximum multipath delay of the channel are extended within the regulated range, the interference-free transmission is realized. The parameter of the spectrum spreading sequence encode block and the efficiency of the system can be adjusted in real time according to practical factors and to select flexibly. The method lowers the requirement of the CDMA communication system on the power control and the synchronization, and reduces the complexity of realizing the system.

The invention belongs to the technical field of an FPGA (field-programmable gate array) and in particular relates to an FPGA interconnection structure supporting the time division switching. On the basis of the structure of an assembly line, time division multiplexing and source-synchronous interconnection, the time slot switching principle which is commonly used in a communication system is combined for providing a novel FPGA interconnection resource structure, the time division switching is used for replacing an original traditional space switching interconnection structure, and the structure adds part of time slot switching on a switching matrix in time division multiplexing interconnection resources, thereby being capable of greatly simplifying the switching matrix and the design of an input and output selector. The novel FPGA interconnection structure can reduce the area of the interconnection resources and improve the logic density of the FPGA, and has the characteristics of being high in performances, reducing the complexity in design, improving the reliability and being low in power consumption.

The invention discloses a neighborhood distance based transmission line fault detection method, and relates to the technical field of fault detection of power transmission lines. The method includes extracting the three-phase current sampling values on the two sides of a line, utilizing abnormal data detection and mean value correction methods, and performing rejecting and correction on abnormal data; performing normalization processing on a current waveform rejecting the abnormal data; extracting the A phase, B phase and C phase current sampling values on the two sides of the line of the last cycle of each sampling point to form the phase current sets on the two sides of the sampling points, and constructing and calculating the neighborhood distances between each phase current set on the two sides; judging the line is failed when one or more neighborhood distances of the line are greater than a protection threshold value; and backward moving a sampling point, and detecting that the line is failed when line fault is continuously judged for three times.

The invention discloses an electronic-control backlash eliminating gear pair with variable tooth thickness. The gear pair comprises a tooth thickness variable gear I, a tooth thickness variable gear II and an electronic-control backlash eliminating system, wherein the tooth thickness variable gear II is meshed with the tooth thickness variable gear I, the electronic-control backlash eliminating system comprises at least an electronic-control power device used for exerting backlash-regulating axial mechanical force on the tooth thickness variable gear I and the tooth thickness variable gear II, and the direction of the backlash-regulating axial mechanical force is a direction for backlash elimination between the tooth thickness variable gear I and the tooth thickness variable gear II. According to the gear pair, real-time control of axial displacement is achieved through electronic control, then the tooth backlash can be regulated in real time according to backlash regulation requirements, the response is rapid, the transmission accuracy is improved, the volume is small, the structure is simple, the synchronism requirement for control is low, the cost is low, the assembling requirements are easy to satisfy, the tooth backlash and the return difference can be eliminated or reduced timely, the transmission error during reversing can be reduced, therefore the operation and the control are simple and fast, and high adaptability is provided at occasions with high requirements for the integral structure.

The present invention is a kind of electrified railway power quality conditioner, comprises single-phase multi-winding transformer, single-phase single-winding transformer, converter (I, II) and electric capacity; One end of the converter I is connected in series, the other end of the converter I is connected in parallel with the capacitor and then connected back to back with the converter II, and the converters II are connected in a chain structure and then connected in series with the single-phase single-winding primary winding. The present invention adopts a single-phase transformer and a chain structure, which can reduce switching loss, improve device operation efficiency and reliability, reduce the number of device links, reduce the complexity of device structure, improve control accuracy, and reduce the pulse output to the control system Synchronization requirements. The invention solves the problems of negative sequence, reactive power and harmonic exceeding standard in the traction station of the electric railway, and has the advantages of small occupied area of ​​the device, small loss, simple control, low cost and high reliability.

The invention provides a multi-hop broadband wireless communication system and a wireless node device thereof. The system comprises a console and a plurality of wireless node devices which are in tree-shaped or chain-shaped wireless network connection, wherein the wireless node devices at least include a data transmission control unit, a child-phase wireless transceiver unit and / or father-phase wireless transceiver unit; the child-phase / father-phase wireless transceiver units are used for sending downlink / uplink data to adjacent sub nodes, for receiving downlink / uplink data from adjacent sub nodes, and extracting a physical layer service data block and the corresponding destination address from the data, and then sending the information to a data transmission control unit; and the data transmission control unit is used for receiving uplink / downlink physical layer service data block and the corresponding destination address from the child-phase / father-phase wireless transceiver units, and for controlling and forwarding the data according to the destination address. Due to the adoption of the system, the delay of the relay data forwarding is reduced, and the flexibility and efficiency of the relay transmission are improved.

The invention discloses a binary space chaos laser communication system based on a first-order transverse mode and relates to the field of chaos laser communication. The system comprises a transmitting module and a receiving module. The transmitting module is used for coupling signal light composed of two modes of lasers with a carrier, forming an overlapped signal and transmitting the overlappedsignal. The receiving module is used for receiving and demodulating the overlapped signal, detecting power at different locations on the same section of the signal and further identifying a mode. According to encryption mode provided by the invention, a chaos system monitoring mode for laser signal power detection is bypassed, so the confidentiality of a chaos system is improved. A high-order modehas relatively high coupling capability. The coupling loss among devices can be reduced. The transmission precision degree can be improved.

The invention discloses a novel motor train unit bogie replacing unit which comprises a main body framework, a supporting head mechanism and a ballast bed mechanism. A supporting head can be driven byitself along a supporting head walking rail so as to be aligned with a motor train unit lifting point. The ballast bed mechanism comprises a ballast bed and a lifting mechanism; the ballast bed is provided with a rail; and the lifting mechanism drives the ballast bed to reciprocate in a height direction so that the rail is selectively in butt joint with the fixed rail to form a continuous rail oris in butt joint with a negative working layer. When the lifting mechanism drives the ballast bed to be in a lifting state, the rail and the fixed rail are in butt joint to form the continuous rail.When the lifting mechanism drives the ballast bed to descend from the lifting state to a first descending state, the rail is in butt joint with the negative working layer, and the supporting head lifts a carriage. Synchronous lifting is easy to control, the unit is suitable for replacement operation of motor train unit bogies of all types, and an underground space can be effectively utilized for maintenance operation.

The invention discloses double planetary transmission hoisting mechanisms for a ladle crane, comprising two sets of driving systems and steel wire rope systems, wherein the steel wire rope systems are respectively composed of a fixed pulley block, a winding drum group, a steel wire rope and a movable pulley block on a lifting appliance; the driving systems respectively comprise two electromotors,two service brakes, an emergency brake and a reducer with a planetary packet; the electromotors are connected with a reducer by a coupling; an output shaft of the reducer is connected with the coupling of a winding drum; the coupling of the winding drum is connected with the winding drum group; and one side, which closes to the reducer, of the winding drum group is provided with a gear pair. The double planetary transmission hoisting mechanisms for a ladle crane is characterized in that two low-speed ends of the two sets of driving systems are rigidly connected by the gear pair; the output shafts of the electromotors are provided with the service brake respectively; and the emergency brake is connected with or arranged on a planet carrier shaft by a pair of overdrive gears. The double planetary transmission hoisting mechanisms for a ladle crane have the advantages of being simple in control and light in weight, improved safety, reduced cost, and being more convenient to maintain.