The control of vibration is important for four main reasons To improve crew efficiency, and hence safety of operation;2. To improve comfort of passengers;3. To improve the reliability of avionics and mechanical equipments;4. To improve the fatigue lives of airframe structural components Hence it is very important to control vibration throughout the design, development and in-service stages of a helicopter project 13 Examples of these passive vibration reductionstrategies include tuned-mass absorbers, isolators, and blade design optimizations.
Figure 3. Without adding mass, an aircraft battery may be usedas the mass in the absorber assembly. For example, a helicopter known as sea king uses its battery vibration absorber or the mass may be parasitic, as in certain models of the Boeing Vertol Chinook helicopter, where five vibration absorbers one in the nose, two under the cockpit floor and two inside the aft pylon are usedSea King battery vibration absorber Boeing-Vertol CH "Chinook"17 A centrifugal pendulum type of absorber mounted onthe rotor blade is another type.
This type of absorberhas been used on the Bolkow Bo and Hughes helicopters Next Figure shows the Hughes installation whichconsists of absorbers tuned to the 3 and 5excitation frequencies for the four-bladed rotorversion, 18 In general, an active vibration reductionsystem consists of four main components;sensors, actuators, a power supply unit,and a controller Figure Actuators Sensors Controlled Structure Controller The principle of operation is: based on the sensor input and a mathematical modelof the system, generates an anti vibration field, thatis, as closely as possible identical to the uncontrolledvibration field but with opposite phase 20 If these two vibration fields the uncontrolled and theactuator generated were identical in amplitude andhad exact the opposite phase, then the addition of thetwo fields would lead to complete elimination of thevibrations levelsAlso, the controller can be configured to adjust itselffor any possible change in operating conditions usingan adaptive control scheme.
Transducers mounted at key locations in the fuselagemeasure the vibration, and this data is analyzed by an onboardcomputerBased upon this data, the computer generates, using optimalcontrol techniques, signals which are transmitted to a set ofactuators 22 Instead of placing the actuators in the non- rotating frame HHC concept , the IBC approach uses actuators located in the rotating frame to provide, for example, blade pitch, active flap, and blade twist inputs for vibration reduction. Schemetics of Individual Blade Control IBC systems are shown below: a blade pitch, b active flap, and c blade twist controls 26 The calculated outputs will be fed toappropriate actuators, locatedthroughout the airframe, to produce thedesired active forcesFigure 3.
The basis of ACSR is that, if a force F is applied to astructure at a point P and an equal and opposite force the reaction is applied at a point Q, then the effectwill be to excite all the modes of vibration of thestructure which possess relative motion betweenpoints P and Q This requirement for relative motion in the modalresponse between the points where the actuator forcesare applied is an essential feature of ACSR. Commonly used force actuators include electro-hydraulic Piezoelectric, and inertial force actuators Extensive studies on ACSR system have beenconducted analytically and experimentally.
Semi-active Vibration Reduction TechnologySemi-active vibration reduction concepts aredeveloped to combine the advantages of both purelyactive as well as purely passive concepts. Semi-active strategies achieve vibration reduction bymodifying structural properties, stiffness or damping,of semi-active actuatorsSemi-active vibration reduction concepts have alreadybeen investigated in several engineering applicationsbut only very recently has there been any focus onusing them to reduce helicopter vibrationMajor differences between active and semi-activeconcepts are their actuators and associatedcontrollers.
Active actuators generally provide direct active force,while semi-active actuators generate indirect semi-active force through property modification. There are several advantages for using the semi-active concepts over the active concepts: 32 PartMaker Inc. The software automatically extracts critical manufacturing data to produce web-based reports and analytics on asset utilization, availability, performance, quality, and overall equipment effectiveness.
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The software integrates with ERP, MES, maintenance and quality business systems, and can be accessed via smartphone or tablet device. The Exerial 3D printing system allows customers to engage with indirect printing technology for industrial series production beyond rapid prototyping and small batch production. The printing system contains multiple industrial stations that allow for continuous production and simultaneous processing and is equipped with two job boxes, each 1.
The system offers a total build platform of 3,L and is expected to be capable of printing output rates nearly 4x faster than the S-Max. ExOne www. The MUV vertical machining center is suitable for 5-axis, multi-sided machining. The machine is available with a wide array of spindle options, providing a configuration for nearly any 5-axis job.
The design places the pallet changes at the back of the machine, allowing easy connection to a Palletace flexible manufacturing system or pallet pool, delivering high productivity and accuracy. The MUV has a rigid double column structure and low center of gravity in workpiece movement that enables heavy-duty cutting and high-speed finishing. Okuma America Corp. The 3D animations of CNC machining processes and work instruction sheets are directly accessible from the mobile application.
The LMWS laser marking workstation, designed for benchtop operation, features a fresh, industrial design, with improved functionality, narrow width for lean manufacturing, and CDRH Class 1 safety. Integrated with a fiber laser marker, the LMWS is capable of marking metals, ceramics, and many plastics, and also has cutting, drilling, and welding capabilities. Requiring minimal workspace, the updated unit works in low-volume production and research and development environments.
Miyachi America Corp. The ScopeCheck multisensor coordinate measuring machine CMM has a measurement range up to 3,mm in the X axis and 1,mm in the Y axis.
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Existing functions of the WinWerth 7. Temperature compensation is standard. Werth Inc. The Aspect delivers arc stability and uses AC Auto-Balance technology to adjust cleaning and penetration levels during aluminum welding. The system has Intellistart technology to automatically control arc starting intensity for thin or thick materials. Lincoln Electric www. The Federal Aviation Administration FAA has established an interim policy to speed up airspace authorizations for certain commercial unmanned aircraft UAS operators who obtain Section exemptions.
The interim policy bridges the gap between the past process, which evaluated every UAS operation individually, and future operations after the FAA issues its final version of the proposed small UAS rule, expected later this year. Previously, an operator had to apply for and receive a COA for a particular block of airspace, a process that can take 60 days. The agency expects the new policy will allow companies and individuals who want to use UAS within these limitations to start flying much more quickly.
Section exemption holders will automatically receive a blanket ft COA.
Most of these have been for UAS use in inspecting power transmission line, oil and gas, and electric grid infrastructures; wind turbine towers; photogrammetry; real estate and marine aerial photography; mapping; and precision agriculture. A balloon-assisted unmanned aerial vehicle UAV named Phoenix-S1, developed by Kyushu University and Fukuoka University, Japan, has successfully brought back stratospheric aerosol samples from an altitude of 22km and observed aerosol density 23km above Antarctica.
The observation on Jan. Yoshifumi Nogi. After the balloon burst at an altitude of 23km, the UAV descended by parachute, was released, and glided back to the launch site autonomously.
V-22 Osprey: Unlike any aircraft in the world
The researchers believe this is the highest observation altitude for a small UAV. They reported that the method was effective in retrieving the observation apparatus and aerosol samples from the upper atmosphere easily and at low cost. Under this contract, Raytheon will deliver one building-based and one mobile ground segment to locations in South Korea.
General Atomics Aeronautical Systems Inc. Predator B achieved this record on Feb.
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Predator B flight hours now account for approximately one-third of the 3. These aircraft support the U. Air Force, U. Missions include direct support to warfighters, assisting border agents, aiding first responders, and supporting Earth science missions. GA-ASI has delivered more than Predator B aircraft to date and is currently building three aircraft per month, with the capacity to more than double production if needed.
These capabilities are core in a world dominated by globally integrated enterprises. Pictometry, an EagleView Technology company, has received an unmanned aerial systems UAS research project to focus on the feasibility of using UAS to improve the overall safety and speed of routine and emergency surveys and inspections of gas utility pipelines.
The YF's Weapons Bay Layout Was One Of Its Best Features And One Of Its Worst - The Drive
The team will perform ongoing research experimentation in approved areas using a UAS with high-resolution cameras and potentially methane detection devices to enhance pipeline safety. UAV Turbines Inc. The engines offer increased reliability, flight duration, payloads, and operational ceilings, while reducing noise. Fuel consumption is low, using a variety of heavy fuels.
Based in Miami, Florida, privately held UAV Turbines is demonstrating prototypes of its engines to potential qualified buyers. What is an electromagnetic field? Control and planning Avionic systems contain a large number of on-board, frequency-generating systems including frequency synthesizers, digital circuits, telemetry, and switching power supplies. Board level shielding Available in a variety of sizes and heights, board level shielding BLS can be specified with any number of compartments. Gasketing Gaskets maintain shielding by properly treating seams.
Joana, V. Shieh, M. Smith, J. Summerskill, S. Wang, J. Wang, Y. Borgianni, Y. Zhang, J. Personalised recommendations. Cite paper How to cite? ENW EndNote.
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