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Leveraging advances in shape memory alloys (SMAs) and flexible thermoelectric devices (f-TEDs), this paper presents a structural and functional integrity composite sheet to address the inefficient and bulky activation of 2-D SMAs. A series of experimental tests were performed to reveal the generation, change, and transfer mechanisms of different types of electrically-induced heat in the f-TED, as well as the temperature-induced SMA phase transformation behaviors. The results show that the composite sheet exhibited good bidirectional thermal management capacity. The austenite deformation can be completed within 10s at an operating current of 2 A. The cooling recovery, in particular, performs much better than in conventional modes (the temperature declines exponentially with time). Finally, through two functional prototypes, a light switch and a flexible gripper, the application potential of the proposed composite was further experimentally demonstrated. [ABSTRACT FROM AUTHOR]

The attitude determination and control subsystem is tasked with identifying the location and the orientation of the satellite at all times during the mission. Momentum exchange actuators such as reaction wheels are mounted on the satellites to transfer some of their torque, turning them through its centre of mass along each of three axes. In this paper, the design process of a momentum exchange actuator is presented, which has been designed and manufactured in Space Research Laboratory. This device named as RW2000 is the engineering model of reaction wheel for the satellite control simulator. In this approach in designing, design parameters related to the manoeuvrability of the system are considered as the inputs of the design process. After presenting the overall concept of the design process along with constrains, the general analysis of the actuator’s performance is investigated and the related equations are derived. Using the derived equations, the design process is developed. Finally, the engineering model of reaction wheel is designed using the proposed algorithm. The results of the performance test of the manufactured actuator accredit the accuracy and the correctness of the proposed design algorithm. [ABSTRACT FROM PUBLISHER]

This paper presents the results of modeling, simulation and experimental research of the bulk material flow on the electromagnetic vibratory feeder (EVF). The model of the EVF was implemented in Simulink/Matlab and verified in the experimental research. It has been experimentally confirmed that the bulk material flow rate has its maximal value as far as excitation frequency is equal to the EVF mechanical resonant frequency. For certain bulk material flow rate, average value of excitation coil current of EVF has minimal value when named frequencies are equal. In addition to modeling of the EVF, the main contribution of this paper is implementation of flow control algorithm of bulk material on EVF, experimental verification of the adopted model and defines parameters that enable the selection of energy-efficient operating point of the EVF. [ABSTRACT FROM AUTHOR]

In this paper different electrostatic interdigitated comb designs for the new concept of MEMS based DC-AC capacitive power inverter for the solar photovoltaic applications has been compared and tested on the basis of different structures and materials used as a frame for the proposed model. To obtain better the performance and power conversion efficiency of the interdigitated comb drive capacitive DC/AC inverter at very low input voltage some structural parameters of the proposed model has been varied such as increase the number of comb fingers; reduced the gap between the fingers of the interdigitated comb with increase in thickness of the fingers and made uniformly tapered at its edges. As a structural material for the proposed model the polysilicon and indium antimonite has been employed, simulated, compared and tested and in COMSOL Metaphysics 5.0 environment with different comb structure to get better performances for solar photo voltaic application. The proposed MEMS DC/AC power inverter model can easily compete with the commercially available semiconductor inverters once it is implemented with efficient fabrication technology due to its certain merits over semiconductor power inverter in terms of miniaturized size, pure sinusoidal output voltage and current, regulated output frequency, ultra low power consumption, very low cost and off course very small or minimal power loss. [ABSTRACT FROM AUTHOR]

We report the synthesis of cellulose membranes from balsa wood with an exceptionally high responsivity to humidity change by chemical processing and mechanical compression. By varying the ambient humidity, the produced cellulose membranes can provide a variety of predetermined deformations, such as curve, s-like deformation and curl. The high humidity responsivity is originated from a self-maintained moisture gradient induced by an asymmetrical design of membrane surfaces, aided by the hygroscopic swelling of the cellulose. The moisture-driven actuators are then demonstrated as a three-finger gripper that can grab, hold and release objects 40 times the weight of its own. The combination of natural wood and stimuli-responsive behavior open a way to designing smart structures, actuators and soft robots with environmentally friendly, recyclable and biocompatible materials. [ABSTRACT FROM AUTHOR]

We have developed stacked nanocarbon polymer actuators that are composed of several nanocarbon polymer actuator films using nonwoven fabric as insulation layers. The nonwoven fabric prepared through electrospinning methods has extremely-low-density structures, which do not significantly prevent the motions of each nanocarbon actuator layer. Therefore, stacking several thin nanocarbon polymer actuators using nonwoven fabric as insulation layers is expected to increase generated force without decreasing the displacement of a one-layer actuator. We have prepared stacked actuators with one, two, three, four, and seven layers using this method. The displacement and blocking force of these actuators are measured and compared with those of one-layer actuators of different thicknesses. Displacement is weakly dependent on the thickness of the actuator films of the stacked actuators. On the contrary, it decreases considerably as the thickness of the actuator film of the one-layer actuator increases. In both cases, blocking force is proportional to the thickness of actuator films. We have developed a stacked actuator model based on a trilayer actuator model and confirmed the experimental results using the model. [ABSTRACT FROM AUTHOR]

Dielectric elastomers are widely investigated as soft electromechanically active polymers (EAPs) for actuators, stretch/force sensors, and mechanical energy harvesters to generate electricity. Although the performance of such devices is limited by the dielectric strength of the constitutive material, the electrical breakdown of soft elastomers for electromechanical transduction is still scarcely studied. Here, we describe a custom-made setup to measure electrical breakdown of soft EAPs, and we present data for a widely studied acrylic elastomer (VHB 4905 from 3M). The elastomer was electrically stimulated via a planar and a hemispherical metal electrode. The breakdown was characterized under different conditions to investigate the effects of the radius of curvature and applied force of the hemispherical electrode. With a given radius of curvature, the breakdown field increased by about 50% for a nearly 10-fold increase of the applied mechanical stress, while with a given mechanical stress the breakdown field increased by about 20% for an approximately twofold increase of the radius of curvature. These results indicate that the breakdown field is highly dependent on the boundary conditions, suggesting the need for reporting breakdown data always in close association with the measurement conditions. These findings might help future investigations in elucidating the ultimate breakdown mechanism/s of soft elastomers. [ABSTRACT FROM AUTHOR]