The
design of humidity actuators with high response sensitivity
(especially actuation time) while maintaining favorable mechanical
properties is important for advanced intelligent manufacturing, like
soft robotics and smart devices, but still remains a challenge. Here,
we fabricate a robust and conductive composite film-based humidity
actuator with synergetic benefits from one-dimensional cellulose nanofibers
(CNFs) and carbon nanotubes (CNTs) as well as two-dimensional graphene
oxide (GO) via an efficient vacuum-assisted self-assembly method.
Owing to the excellent moisture sensitivity of CNF and GO, the hydrophobic
CNT favoring rapid desorption of water molecules, and the unique porous
structure with numerous nanochannels for accelerating the water exchange
rate, this CNF/GO/CNT composite film delivers excellent actuation
including an ultrafast response/recovery (0.8/2 s), large deformation,
and sufficient cycle stability (no detectable degradation after 1000
cycles) in response to ambient gradient humidity. Intriguingly, the
actuator could also achieve a superior flexibility, a good mechanical
strength (201 MPa), a desirable toughness (6.6 MJ/m3),
and stable electrical conductivity. Taking advantage of these benefits,
the actuator is conceptually fabricated into various smart devices
including mechanical grippers, crawling robotics, and humidity control
switches, which is expected to hold great promise toward practical
applications.
Cooling technologies that address high-density and asymmetric heat dissipation in CPU packages of high-performance servers are discussed. Thermal management schemes and the development of associated technologies are reviewed from a viewpoint of industrial application. Particular attention is directed to heat conduction in the package and heat removal from the package/heat sink module. Power dissipation and package cooling characteristics of high-performance microprocessors are analyzed. The development of a new metallic thermal interface technology is introduced, where thermal and mechanical performance of an indium-silver alloy in the chip/heat spreader assembly was studied. The paper also reports on research on other thermal management materials, such as diamond composite heat-spreading materials. Some actual package designs are described to illustrate the enhanced heat spreading capability of heat pipes and vapor chambers.
Ionic conductive Li 0.33 La 0.56 TiO 3 (LLT) epitaxial thin films were grown on perovskite SrTiO 3 (100), NdGaO 3 (110), and (LaAlO 3 ) 0.3 -(SrAl 0.5 Ta 0.5 O 3 ) 0.7 (100) single crystal substrates by pulsed laser deposition. The use of Li-rich Li 0.84 La 0.56 TiO 3+δ target together with an optimized laser fluence resulted in the growth of phase pure LLT thin films with high growth rate of 2 nm/min. The a-axis and c-axis oriented films were selectively grown by choosing the substrates. Ionic conductivity at room temperature of LLT epitaxial film on NdGaO 3 (110) substrate was close to that of bulk previously reported, representing the highly crystalline quality. In addition, the unequally strained lattice due to different inplane lattice constants of orthorhombic NdGaO 3 substrate resulted in laterally anisotropic ionic conductivity with different activation energy perpendicular to NdGaO 3 [11̅ 0] and [001], 6.7 × 10 −4 S·cm −1 with 0.34 eV and 4.3 × 10 −4 S·cm −1 with 0.36 eV, respectively. This result suggests that the lattice engineering can provide a way to control Li ionic conduction.
Although
humidity-responsive actuators serve as a promising candidate
in smart wearables, artificial muscles, and biomimetic devices, most
of them derived from synthetic polymers could not simultaneously achieve
multifunctional properties. In this work, a cellulose nanofiber (CNF)-based
film actuator with high mechanical properties, excellent Joule heating,
and antibacterial capability is successfully constructed by integrating
with Ti3C2T
x
(MXene)
and tannic acid (TA) via a vacuum-assisted filtration approach. Owing
to the unique nacrelike structure and strong hydrogen bonds, the tensile
strength and toughness of the composite film could reach 275.4 MPa
and 10.2 MJ·m–3, respectively. Importantly,
the hydrophilic nature of CNFs and alterable interlayer spacing of
MXene nanosheets endow the composite film with sensitive humidity
response and extraordinary stability (1000 cycles). With the assistance
of MXene nanosheets and TA, the composite film could not only present
outstanding Joule heating but also possess remarkable antibacterial
properties against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Benefiting from the above merits, the proof-of-concept smart garment
is assembled by the as-prepared film and is capable of regulating
humidity and temperature.
To enhance yaw stability of the vehicle with Active Front Steering System, a vehicle two-degree-of-freedom simple model is set up. The feedback of the yaw rate is regarded as an input; we propose a yaw moment control based on fractionalorder PID controller, and parameters in-line setting in the process of control is realized. The developed controller generates the suitable yaw moment so that the vehicle follows the target values of the yaw rate. A simulation is performed at different conditions. The simulation results show that the yaw rate of controlled vehicle follow the target value of the desired yaw rate, degrading the values of the sideslip angle, when the vehicle is subject to different cornering maneuvers such as change line and step signal.
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