The paper presents a general grapho-analytical methodology for kinematical analysis of whichever plane cam mechanism. The main constructive solutions of plane cam mechanisms are reviewed and the solutions of kinematic...
The paper presents a general grapho-analytical methodology for kinematical analysis of whichever plane cam mechanism. The main constructive solutions of plane cam mechanisms are reviewed and the solutions of kinematical analysis are briefly presented. The most important difficulty in cam mechanisms analysis is the fact that when the follower has a curved face with random shape, the contact point between the cam and the follower has unknown trajectory. At the same time, the contact point moves both on the cam and on the follower contour, respectively. These displacements are required in the study of accelerations. The paper presents a method of analysis directly applicable for actual mechanism which allows finding all kinematical parameters of the mechanism. For structural reasons, there are separately approached the curved-face follower and the flat-face follower cases.
One of the improvements that can be made to internal combustion engines, without significantly altering the structural elements, is increasing the temperature in the combustion chamber by coating its component element...
One of the improvements that can be made to internal combustion engines, without significantly altering the structural elements, is increasing the temperature in the combustion chamber by coating its component elements with thermal barrier coatings (TBC). In this paper were analysed from the microstructure point of view the coating-substrate interfaces of three layers deposited by thermal spraying: S1 - Cr2C3 - NiCr, S2 - MgZrO - NiCr and S3 - ZrO - CaO. The investigations were performed by electronic microscopy on the cross sections taken from the samples after they were subjected to similar heating to the one produced during the operation. It has been observed that all three types of coatings have a much better density, are chemically stable and have good adhesion to the substrate, which recommends them for this type of use.
This paper uses optical whispering galley modes (WGM) cavities to construct a new electrical sensing interface between prosthetic limb and the brain. The sensing element will detect the action potential signal in the ...
This paper uses optical whispering galley modes (WGM) cavities to construct a new electrical sensing interface between prosthetic limb and the brain. The sensing element will detect the action potential signal in the neural membrane and the prosthetic limb will be actuated accordingly. The element is a WGM dielectric polymeric cavity. WGM based optical cavities can achieve very high values of sensitivity and quality factor; thus, any minute perturbations in the morphology of the cavity can be captured and measured. The action potential signal will produce an applied external electric field on the dielectric cavity causing it to deform due to the electrostriction effect. The resulting deformation will cause WGM shifts in the transmission spectrum of the cavity. Thus, the action potential or the applied electric field can be measured using these shifts. In this paper the action potential signal will be simulated through the use of a function generator and two metal electrodes. The sensing element will be situated between these electrodes to detect the electrical signal passing through. The achieved sensitivity is 27.5 pm/V in measuring the simulated action potential signal; and 0.32 pm/V.m-1 in measuring the applied electric field due to the passage of the simulated signal.
Since epicyclic gearboxes are broadly employed in mining and wind turbine industry, they are frequently subjected to highly non-stationary operation conditions, with harsh changes of load and input speed. Therefore, e...
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ISBN:
(纸本)9781510827936
Since epicyclic gearboxes are broadly employed in mining and wind turbine industry, they are frequently subjected to highly non-stationary operation conditions, with harsh changes of load and input speed. Therefore, epicyclic gearbox diagnostic methods should cover for at least three requirements: - Ability to work under rapidly changing speed and loading conditions, - Ability to work in conditions of low angular speed, - Ability to encompass and identify any faulty component of a gearbox. The most commonly used approach to epicyclic gearbox monitoring is based on acquisition of vibration signatures, due to low equipment cost and typically straightforward data acquisition procedures. Unfortunately, most of vibration signal processing and interpretation algorithms do not fulfill requirements enumerated above. This paper identifies and explains some challenges related to monitoring of epicyclic gear trains and provides concepts and solutions that are used to solve them. Capabilities and limitations of popular methods are addressed. Selected damage detection and identification methods including novelty detection approach and 2D representations of vibration signals are illustrated on the basis of data acquired on industrial gearboxes mounted on wind turbines.
In the last decades renewable energy domain has seen a significant development. The wind energy is one of the most important sources of renewable energy. Several research and development directions have been identifie...
In the last decades renewable energy domain has seen a significant development. The wind energy is one of the most important sources of renewable energy. Several research and development directions have been identified to continue installation of the wind turbines: off-shore areas, increased rotor dimensions and installation of small wind turbines. The main objective of this paper is to achieve information about torsional and bending resistance of prototype blade for a three-blade HWAT (Horizontal Wind Axis Turbine). The blade assembly is composed from: a metal hub, a stiffening I-shaped element and blade itself manufactured from composite material. Load condition was created with clamping hub, a concentrated moment on the tip of the blade and a concentred force at 300 mm from tip. Numerical simulations were performed on all three components of the assembly. Results of two cases of numerical simulation are presented for directional deflection on Y axis and equivalent von Mises stress for each component.
The paper deals with a tracking control for robotic manipulators, where the robot dynamics is described by means of Hamiltonian mechanics. This way leads to different physical descriptive quantities used in control de...
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The paper deals with a tracking control for robotic manipulators, where the robot dynamics is described by means of Hamiltonian mechanics. This way leads to different physical descriptive quantities used in control design. In the paper, the model-oriented Lyapunov-based control is considered. It is in-troduced in the novel formulation using Hamiltonian mechanics and compared with the conventional formulation based on Lagrangian mechanics. The theoretical results, generally applicable to usual articulated industrial robotic manipulators, are demonstrated on one specific robot arm with three degrees of freedom.
The T-junction microchannel device makes available a sharp edge to form micro-droplets from biomaterial solutions. This article investigates the effects of injection angle, flow rate ratio, density ratio,viscosity rat...
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The T-junction microchannel device makes available a sharp edge to form micro-droplets from biomaterial solutions. This article investigates the effects of injection angle, flow rate ratio, density ratio,viscosity ratio, contact angle, and slip length in the process of formation of uniform droplets in microfluidic T-junctions. The governing equations were solved by the commercial software. The results show that contact angle, slip length, and injection angles near the perpendicular and parallel conditions have an increasing effect on the diameter of generated droplets, while flow rate, density and viscosity ratios, and other injection angles had a decreasing effect on the diameter.
This study is aiming to emphasize the relation between the force at the paddle and the inclination angle of the support of the leg on the skiff, depending on the anthropometric dimensions of the sportsman. This angle,...
This study is aiming to emphasize the relation between the force at the paddle and the inclination angle of the support of the leg on the skiff, depending on the anthropometric dimensions of the sportsman. This angle, which is adjustable, makes the reaction force between the support and the leg to be decomposed into two components, namely: a horizontal component equivalent to the force at the paddle and a component along the support which is determining the sliding force between the leg and the support. The reaction force between the leg and the support depends also, on the anthropometric dimensions of the thigh and the shank as well as on the extension angles of the thigh and shank. The whole assembly formed of shank, thigh and the sliding chair on which the sportsman is sitting can be likened to an eccentric crank-piston mechanism. The numerical study emphasized that the increasing angle of inclination of the support produces the increasing of the horizontal component of the reaction force leg-support. On the other side, when the shank and the thigh are in prolongation, the inclination angle of the support has to be around 75 degrees so that the entire sole of the foot to be in contact with the support. Using the relations emphasized in the paper, there can be determined the optimum angle, personalized, for each sportsman.
Materials develop different type of behaviours based on environmental conditions, loading conditions and different processing methods. Following up a previous work, the authors noticed that a mainly ductile material h...
Materials develop different type of behaviours based on environmental conditions, loading conditions and different processing methods. Following up a previous work, the authors noticed that a mainly ductile material had features of brittle failure when the material was used for specimens with stress concentrators. Three types of specimens with stress concentrators were chosen and tests were carried out in order to develop a triaxial state of stress using a universal testing machine. After the failure, new specimens of the failure surface were debited and they were studied using SEM analysis. Elements of both brittle and ductile failures were identified and the study went further to verify the chemical composition of the material and the presence of impurities, if any. The authors concluded that the processing methods, the chemical composition and contamination of the material greatly influences the behaviour and type of failure of the specimens.
The most important part of wind turbine is the blade that must be tested during fabrication and functioning when can be damaged by moisture absorption, fatigue, wind gusts or lightning strikes. The common defects in t...
The most important part of wind turbine is the blade that must be tested during fabrication and functioning when can be damaged by moisture absorption, fatigue, wind gusts or lightning strikes. The common defects in turbine blades may be faulty microscopic and mesoscopic appeared in matrix, broken fibers can also appear and develop under moderated loads, or cracks and delaminations due to low energy impacts, etc. The paper propose to present the results obtained from testing and monitoring of a scalable wind turbine blade using different sensors placed on critical location which were determined by finite element method simulation. A comparison between the complementary methods is carried out.
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