Transformable structures in architecture can adapt their shape or function offering dynamic answers to modern problems, such as deployement for creating temporary spaces, responsiveness to climatic influences and chan...
Transformable structures in architecture can adapt their shape or function offering dynamic answers to modern problems, such as deployement for creating temporary spaces, responsiveness to climatic influences and change of use, in a society which embraces the concept of sustainable design. Depending on how the transformation is carried out, transformable structures can be deployable or demountable, as a kit-parts system. According to their structural system, deployable structures can also be classified in four main groups: spatial bar structures; foldable plate structures; tensegrity structures; and membrane structures. In this paper, a review on the deployable structures based on foldable plate structures will be done.
These mechanisms have gained prowess because of the benefits they offer, especially obtaining high reduction ratios in one reduction step. In addition, there is no longer the risk of trochoid interference that may occ...
These mechanisms have gained prowess because of the benefits they offer, especially obtaining high reduction ratios in one reduction step. In addition, there is no longer the risk of trochoid interference that may occur in the case of the internal cylindrical gears when the teeth numbers difference is small. Since the satellite performs a nutation motion, these gears are also called nutation gears. The purpose of this paper is to propose some new nutation geared mechanisms using bevel internal gears having small difference in numbers of teeth. Based on these mechanisms, some robotic wrists will be proposed in another paper of the same journal.
This article presents the design methodology, optimization, and computational verification of a compact, high-gain planar XY flexure mechanism. The presented mechanism consists of a decoupled XY mechanism, and a modif...
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ISBN:
(纸本)9781538603475
This article presents the design methodology, optimization, and computational verification of a compact, high-gain planar XY flexure mechanism. The presented mechanism consists of a decoupled XY mechanism, and a modified Scott-Russel mechanism, which maintain linear XY motion, and amplify the input piezoelectric actuator (PEA) displacement respectively. Each mechanism offers the potential for use in isolation. When operated together, the combined mechanism is capable of nanometer scale precision and millimeter scale range in a vacuum-compatible design. The presented mechanism could therefore be used in micro-assembly operations including those performed in electron microscopes. The design methodology and mechanism models are presented, with the selected design computationally optimized and analyzed. By using a broad design space, and minimizing assumptions, the optimized mechanism produces workspace of approximately 930 × 940 μm 2 from 15 μm of input displacement.
Growth can be defined as an increment in biomass or an increment in weight or height of the organs of the plant influenced by physiological *** of these processes have their limits genetically determined,but climate a...
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Growth can be defined as an increment in biomass or an increment in weight or height of the organs of the plant influenced by physiological *** of these processes have their limits genetically determined,but climate and irrigation play an important *** of its importance,microclimate has been extensively studied in the modeling as a surrounding condition which is imposed by the exterior *** main objective of this work was to develop a temperature model based on the energy balance dynamics at two different greenhouse locations-South-eastern Spain and Northern China,and the traditional structures of Chinese solar greenhouse and Almería-type multi-span greenhouse were taken into *** final model was developed by combining the external conditions,the actuator influence and the crop growth,where the temperature is influenced by soil,crop,cover,actuators,back wall and greenhouse *** model took into account the energy lost by convective and conductive fluxes,as well as the energy supplied by solar radiation and heating *** soil and the back wall are the main media for energy *** temperature dynamic was determined by a physical model,which considered the energy balance from a holistic point of view-as a sub-model for a customizable interface among the external climate,the plant and the greenhouse *** influences of different subsystems included in the temperature model were analyzed and *** results showed a high R^(2)value of 0.94 for Beijing and 0.95 for Almeria,and the average error was low,of which the MAE and RMSE were 0.71 and 1.365 for Almeria and 0.62 and 1.102 for Beijing,***,the model can be considered as a powerful tool for control design purposes in microclimate systems.
The paper deals with a combined approach to approximation of velocity fields and minimization the objective functional in solving viscous fluids flow problems. The mathematical formulation of the problem is presented ...
The paper deals with a combined approach to approximation of velocity fields and minimization the objective functional in solving viscous fluids flow problems. The mathematical formulation of the problem is presented in the form of a generalized Lagrange functional. The flow function is designed using a feed forward artificial neural network with one hidden layer and with logistic activation function. The boundary values of the flow function are determined using the fluid flow rate. Thus, the problem of determination the velocity field is reduced to the problem of finding the network weights by minimizing the generalized Lagrange functional.
Passivity has been the most common tool to achieve stability in haptic and teleoperation systems; however passivity-based approaches suffer from the conservativism of passivity criteria. Therefore, it is essential to ...
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Passivity has been the most common tool to achieve stability in haptic and teleoperation systems; however passivity-based approaches suffer from the conservativism of passivity criteria. Therefore, it is essential to have an approach which is less conservative than conventional approaches, enabling the user to have an immersive experience when interacting with the virtual or remote environment. This paper proposes a Lyapunov observed and controller (LOLC) which has an improved transparency as it uses the Lyapunov boundedness theorem that is less conservative than passivity theorem. The proposed approach also gives the user the freedom to define a relaxed Lyapunov candidate regarding state stability to be chosen. Moreover, the application of the proposed control architecture is not limited to haptic interfaces, and the proposed control methodology could be used to stabilize any control systems. The advantages of the proposed approach to the passivity observer and controller are highlighted via numerical evaluations.
The paper represents an extension of researches in this field, started and published by authors many years ago. The central idea of these research series is notion of structural group, used in forces transmission desc...
The paper represents an extension of researches in this field, started and published by authors many years ago. The central idea of these research series is notion of structural group, used in forces transmission description and also in singularities study. Thus, problems regarding forces transmission indices were presented until now referring to mechanisms containing usual structural groups: 0/2/2 (dyad type – in all their 5 aspects), 0/3/3 with revolute joints and 0/4/2 with revolute joints. For these structural groups were presented both theoretical basis and applications. Naturally, with this paper, we pass to a more complex mechanisms category – six bar planar chains Watt and Stephenson.
Robotic rehabilitation devices are able to meet certain requirements for long time rehabilitation, such as compact design, repeatability and storage patients' evolution. As ankle injuries have a high incidence amo...
Robotic rehabilitation devices are able to meet certain requirements for long time rehabilitation, such as compact design, repeatability and storage patients' evolution. As ankle injuries have a high incidence among the population, regardless of their age or activity, the need for an easy to manufacture rehabilitation device emerges. The proposed design offers two degrees of freedom, required for a full recovery of the ankle joint and programmable exercises. Although a safety button can be included in the electronic system that can be operated by the patient, extra safety measures are required in order not to damage furthermore the rehabilitated limb. A compliant mechanism that can bear the extra load from the motors' crank, in case of overloading of the joint, is required. In this paper some design requirements and systematic synthesis methods for a compliant mechanism are presented.
Based on the biodegradable biomaterial development, there are numerous studies demonstrating partial or total aspects that have ultimately led to their use in many fields, especialy in medicine. This study summarizes ...
Based on the biodegradable biomaterial development, there are numerous studies demonstrating partial or total aspects that have ultimately led to their use in many fields, especialy in medicine. This study summarizes the latest information on the development of degradable biomaterials based on magnesium, especially used in in vivo tissue compatibility assessment. The biomaterial compatibility assessment combines with the development of medical devices, this study following evolutionary parameters and integration of implants for human use. One of the most important parameters is the efficiency with which the medical device works near to the maximum potential. In conclusion, our study aims to broadly present the in vivo analysis of biodegradable biomaterials based on magnesium.
Friction torque in an angular contact ball bearing is dependent on the motion of the balls, lubricant viscosity and quantity, rotational speed and applied loads. To evaluate the friction torque in a ball bearing, the ...
Friction torque in an angular contact ball bearing is dependent on the motion of the balls, lubricant viscosity and quantity, rotational speed and applied loads. To evaluate the friction torque in a ball bearing, the SKF methodology includes the geometrical parameters, lubricant viscosity and type of lubrication, operation speeds and applied loads (radial and axial). As is indicated in the SKF catalogue, the above-mentioned methodology can be used for applied loads equal to or larger than the recommended minimum load indicated. For very low applied loads and for dry or limit conditions, the SKF catalogue doesn't indicate the adequate models to estimate the friction torque. Also, the presence of the cage is not directly included in the SKF methodology. Based on the spin down methodology, the authors performed experimental investigations on a 7205B modified angular contact ball bearing, by using only three balls with and without the cage. Experimental friction torques on the outer race has been obtained in dry conditions and the results were compared with the results obtained from the SKF catalogue. Important differences have been obtained. Also, it was evidenced that at very low loads the presence of the cage leads to an increase in the friction torque with more than one order of magnitude.
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