Microtentacle Actuators Based on Shape Memory Alloy Smart Soft Composite

Recent advances in miniature robotics have brought promising improvements in performance by leveraging the latest developments in soft materials, new fabrication schemes, and continuum actuation. Such devices can be used for applications that need delicate manipulation such as microsurgery or investigation of small‐scale biological samples. The shape memory effect of certain alloys is one of the promising actuation mechanisms at small scales because of its high work density and simple actuation mechanism. However, for sub‐millimeter devices, it is difficult to achieve complex and large displacement with shape memory alloy actuators because of the limitation in the fabrication process. Herein, a fabrication scheme for miniaturized smart soft composite actuator is proposed by utilizing two‐photon polymerization. The morphing modes are varied by changing the direction of the scaffold lamination. In addition, the actuation is controlled via local resistive heating of a carbon nanotube layer deposited inside of the actuators. The proposed design can generate a 390 µN force and achieve a bending angle up to 80°. Applications of the actuators are demonstrated by grasping small and delicate objects with single and two finger devices.     

Covalent 0D–2D Heterostructuring of Co9S8–MoS2 for Enhanced Hydrogen Evolution in All pH Electrolytes

Ultrasmall Co₉S₈ nanoparticles are introduced on the basal plane of MoS₂ to fabricate a covalent 0D–2D heterostructure that enhances the hydrogen evolution reaction (HER) activity of electrochemical water splitting. In the heterostructure, separate phases of Co₉S₈ and MoS₂ are formed, but they are connected by Co–S–Mo type covalent bonds. The charge redistribution from Co to Mo occurring at the interface enhances the electron‐doped characteristics of MoS₂ to generate electron‐rich Mo atoms. Besides, reductive annealing during the synthesis forms S defects that activates adjacent Mo atoms for further enhanced HER activity as elucidated by the density functional theory (DFT) calculation. Eventually, the covalent Co₉S₈–MoS₂ heterostructure shows amplified HER activity as well as stability in all pH electrolytes. The synergistic effect is pronounced when the heterostructure is coupled with a porous Ni foam (NF) support to form Co₉S₈–MoS₂/NF that displays superior performance to those of the state‐of‐the‐art non‐noble metal electrocatalysts, and even outperforms a commercial Pt/C catalyst in a practically meaningful, high current density region in alkaline (>170 mA cm^?2) and neutral (>60 mA cm^?2) media. The high HER performance and stability of Co₉S₈–MoS₂ heterostructure make it a promising pH universal alternative to expensive Pt‐based electrocatalysts for practical water electrolyzers.     

Effect of IQ Mismatch Compensation in an Optical Coherent OFDM Receiver

The performance enhancement using the Gram–Schmidt orthogonalization procedure (GSOP) for compensating transmitter (Tx) and receiver (Rx) in-phase/quadrature (IQ) mismatch in the coherent optical orthogonal frequency-division-multiplexing system is investigated. The analytic result containing frequency offset is presented to describe the different behavior of Tx and Rx IQ mismatch. Bit-error-rate curves measured at back-to-back and 1040-km transmission over single-mode fiber indicate that the GSOP is more efficient to compensate of Rx IQ mismatch than Tx IQ mismatch.      

Plasmonic Light Beaming Manipulation and its Detection Using Holographic Microscopy

Plasmonic off axis beaming and focusing of light by the use of asymmetric or non-periodic dielectric gratings around a metallic slit are experimentally demonstrated. The far-field probing was done by holographic microscopy. While the conventional near-field microscopes can probe only near-fields, our four-step phase-shift interferometer provides an efficient way of probing and reconstructing light paths coming out from the plasmonic devices. We hope our experimental work contributes to the practical applications of plasmonics such as optical interconnection and optical data storage.      

High-Temperature Stability of Thermoelectric Skutterudite In0.25Co3FeSb12

The thermal stability of skutterudite-based thermoelectric modules is of great importance since they are used at elevated temperatures. This study examined the high-temperature stability of In-filled and Fe-doped skutterudites (In_0.25Co₃FeSb₁₂) as a function of the following aging variables: atmosphere (vacuum and air), temperature, and time. Sb-based oxides are produced preferentially on exposure to high temperatures in air. The oxide layer produced during aging at 823?K in air was much thinner than that produced during aging at 723?K in air. The formation of InSb is believed to retard the oxidation of Sb and act as an obstacle to the growth of the oxide layer. The CoSb₃-based skutterudites were stable at 823?K if they were not exposed to air, and InSb phases were not produced in the In_0.25Co₃FeSb₁₂ skutterudites.     

Fault-Tolerant UAV Data Acquisition Schemes

Wireless Personal Communications - Through the use of UAV, the functional lifetime of WSN can be elongated in exchange for higher data delivery latency as the UAV replaces the multi-hop...     

Evaluation of Feature Robustness Against Technical Parameters in CT Radiomics: Verification of Phantom Study with Patient Dataset

Recent advances in radiomics have shown promising results in prognostic and diagnostic studies with high dimensional imaging feature analysis. However, radiomic features are known to be affected by technical parameters and feature extraction methodology. We evaluate the robustness of CT radiomic features against the technical parameters involved in CT acquisition and feature extraction procedures using a standardized phantom and verify the feature robustness by using patient cases. ACR phantom was scanned with two tube currents, two reconstruction kernels, and two fields of view size. A total of 47 radiomic features of textures and first-order statistics were extracted on the homogeneous region from all scans. Intrinsic variability was measured to identify unstable features vulnerable to inherent CT noise and texture. Susceptibility index was defined to represent the susceptibility to the variation of a given technical parameter. Eighteen radiomic features were shown to be intrinsically unstable on reference condition. The features were more susceptible to the reconstruction kernel variation than to other sources of variation. The feature robustness evaluated on the phantom CT correlated with those evaluated on clinical CT scans. We revealed a number of scan parameters could significantly affect the radiomic features. These characteristics should be considered in a radiomic study when different scan parameters are used in a clinical dataset.

     

Effects of multiple threshold values in double dwell DS-SS codeacquisition systems

We describe a decision method using multiple threshold values for direct-sequence spread-spectrum (DS-SS) code acquisition systems. We apply this technique to a conventional double dwell serial search algorithm and analyze it in terms of mean code acquisition time. Numerical results show that our proposed scheme outperforms the conventional one by 0.2-0.5 sec with respect to the mean code acquisition time because multiple threshold values mitigate the possible decline in search performance caused by the use of a single threshold