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排序方式: 共有871条查询结果,搜索用时 31 毫秒
81.
Heather F. Jackson Daniel D. Jayaseelan William E. Lee Michael J. Reece Fawad Inam Dario Manara Carlo Perinetti Casoni Franck De Bruycker Konstantinos Boboridis 《International Journal of Applied Ceramic Technology》2010,7(3):316-326
Melting temperatures of zirconium carbide were investigated in validating a novel thermal analysis technique for refractory materials. Commercial ZrC0.96 powder was densified by spark plasma sintering to >96% relative density after 6–30 min at 2173–2453 K under 40–100 MPa. Sintered ceramics were heated to >4000 K via pulsed laser heating. Mean values for solidus and liquidus transitions were 3451 and 3608 K, respectively, in fair agreement with the present phase diagram. Postmelting analysis revealed dendritic microstructure and composition consistent with single-phase ZrC. Subsurface gas porosity and ZrC–C eutectic indicate complex processes occurring during melting and freezing. 相似文献
82.
83.
The performance of mixed bi-material electrodes composed of the battery material, LiMn2O4, and the electrochemical capacitor material, activated carbon, for hybrid electrochemical energy storage devices is investigated by galvanostatic charge/discharge and pulsed discharge experiments. Both, a high and a low conductivity lithium-containing electrolyte are used. The specific charge of the bi-material electrode is the linear combination of the specific charges of LiMn2O4 and activated carbon according to the electrode composition at low discharge rates. Thus, the specific charge of the bi-material electrode falls between the specific charge of the activated carbon electrode and the LiMn2O4 battery electrode. The bi-material electrodes have better rate capability than the LiMn2O4 battery electrode. For high current pulsed applications the bi-material electrodes typically outperform both the battery and the capacitor electrode. 相似文献
84.
A demand-assignment algorithm based on a Markov modulated chain prediction model for satellite bandwidth allocation 总被引:1,自引:0,他引:1
This article deals with the problem of the design of a control-based demand-assignment algorithm for a satellite access network
using a Markov modulated chain traffic prediction model. The objective is to guarantee a target Quality of Service (QoS) to
Internet traffic, while efficiently exploiting the air interface. The proposed algorithm is in charge of dynamically partitioning
the uplink bandwidth capacity in a satellite spotbeam among the in-progress connections. Such partition is performed aiming
at matching the QoS requirements of each connection and maximizing the satellite bandwidth exploitation. A closed-loop Control
Theory approach is adopted to efficiently tackle the problem of the delay between bandwidth requests and bandwidth assignments,
while minimizing the signaling overhead caused by control messages. The algorithm efficiently copes with both the satellite
propagation delay and the delays inherent in the periodic nature of the bandwidth request mechanism. The proposed demand-assignment
algorithm and Markov chain traffic prediction model are shown to improve the overall satellite network performance through
extensive simulation experiments. 相似文献
85.
Steerable miniature jumping robot 总被引:2,自引:0,他引:2
Mirko Kovač Manuel Schlegel Jean-Christophe Zufferey Dario Floreano 《Autonomous Robots》2010,28(3):295-306
Jumping is used in nature by many small animals to locomote in cluttered environments or in rough terrain. It offers small
systems the benefit of overcoming relatively large obstacles at a low energetic cost. In order to be able to perform repetitive
jumps in a given direction, it is important to be able to upright after landing, steer and jump again. In this article, we
review and evaluate the uprighting and steering principles of existing jumping robots and present a novel spherical robot
with a mass of 14 g and a size of 18 cm that can jump up to 62 cm at a take-off angle of 75°, recover passively after landing,
orient itself, and jump again. We describe its design details and fabrication methods, characterize its jumping performance,
and demonstrate the remote controlled prototype repetitively moving over an obstacle course where it has to climb stairs and
go through a window. (See videos 1–4 in the electronic supplementary material.) 相似文献
86.
Weiting Liu Fei Li Cesare Stefanini Dajing Chen Paolo Dario 《Robotics and Autonomous Systems》2010,58(10):1138-1148
This paper focuses on the development of biomimetic sensory abilities for an undulatory soft-body lamprey-like robot, which has been designed to replicate the locomotion mechanisms of living lamprey in order to address useful applications wherever locomotion in unstructured environments is required. The compliant sensory elements are piezo-resistive and made from compliant material called a quantum tunneling composite by mixing micro/nano carbon black particles into a highly soft silicone rubber matrix. The relationship of the composite strip between piezo-resistivity and mechanical strain is investigated by a universal strain–stress tensiometer through resistivity monitoring. Increasing and decreasing resitivity both appears during elongation and retraction, suggesting that piezo-resistivity in the composite material is governed by both percolation theory and quantum tunneling effects. Dynamic tests on the bench shows that the compliant stretch receptor is able to follow the stimulations under fairly wide frequency ranges, exceeding initial estimations. In addition, the compliant artificial stretch receptor has enough sensitivity to detect the local actuations and the actions generated by neighboring actuators in the segmented robotic structure. Finally, the experiments on biomimetic cilia-based cupula receptor show that a low cost flexible/compliant biomimetic sensor is able to detect medium fluidic speeds ranging from 0.05 m/s to 0.6 m/s. 相似文献
87.
M. Del Maestro F. Cecchi S.M. Serio C. Laschi P. Dario 《Sensors and actuators. A, Physical》2011,165(2):155-163
The study and measurement of grasping actions and forces in humans is important in a variety of contexts. In infants, it can give insights on the neuro-motor development and on pathological dysfunctions, while it poses functional and operative requirements that are not fully matched by current sensing technology. Novel approaches for measuring infants’ grasping actions are based on sensorized toys usable in natural settings. In this paper, we present a sensing device for measuring grasping force in 4–9-month-old infants. Starting from technical and clinical specifications, we designed and developed a novel device made by silicone, shaped as a ring toy and equipped with a pressure sensor, able to measure the pressure exerted by the infant's hand in the range of 0–5 psi. A mechanical model of the material has been developed and tensile compression tests have been executed in order to assess the mechanical and electrical characteristics of the sensing device. The proposed device complies with the (technical and clinical) specifications and results suitable for measuring the grasping forces of the targeted infants, and finally for monitoring infants’ motor development. The theoretical model developed and the methodology for designing and characterizing the sensing device allow for easy re-design and adaptation of the sensing device and consideration of a variety of possible applications. 相似文献
88.
89.
Tobias Schröder Satya Narayan Sahu Dario Anselmetti Jochen Mattay 《Israel journal of chemistry》2011,51(7):725-742
Self-assembly by H-bonding and by metal-coordination of functionalized calix[4]arenes and cavitands to large supramolecular capsules is described. In addition, a new method of analyzing supramolecular recognition processes at the single molecule level is discussed. By measuring interaction forces in a hydrogen-bonded assembly using single-molecule force spectroscopy (SMFS), the dynamics of the self-assembly process can be evaluated. In the future, consequent application of this new technique will influence supramolecular design principles and the use of non-covalent interactions as construction elements in the field of nanotechnology. 相似文献
90.