Zero-static-power nonvolatile logic-in-memory circuits for flexible electronics

Flexible logic circuits and memory with ultra-low static power consumption are in great demand for battery-powered flexible electronic systems.Here,we show that a flexible nonvolatile logic-in-memory circuit enabling normally-off computing can be implemented using a poly(1,3,5-trivinyl-1,3,5-trimethyl cyclotrisiloxane) (pV3D3)-based memristor array.Although memristive logic-in-memory circuits have been previously reported,the requirements of additional components and the large variation of memristors have limited demonstrations to simple gates within a few operation cycles on rigid substrates only.Using memristor-aided logic (MAGIC) architecture requiring only memristors and pV3D3-memristor with good uniformity on a flexible substrate,for the first time,we experimentally demonstrated our implementation of MAGIC-NOT and-NOR gates during multiple cycles and even under bent conditions.Other functions,such as OR,AND,NAND,and a half adder,are also realized by combinations of NOT and NOR gates within a crossbar array.This research advances the development of novel computing architecture with zero static power consumption for batterypowered flexible electronic systems.     

Vision-Based Indoor Localization for Unmanned Aerial Vehicles

Small unmanned aerial vehicles are cost-effective and easy to operate, and especially suitable in dangerous indoor environments. However, because GPS is not available in an indoor environment, indoor localization is a crucial problem in developing small unmanned aerial vehicles (UAVs). This paper suggests vision-based indoor localization for UAVs in GPS-denied environments. Our approach is based on image matching by applying the scale invariant feature transform algorithm.     

Effective thermal conductivity of MgH2 compacts containing expanded natural graphite under a hydrogen atmosphere

Expanded natural graphite (ENG) was added to enhance the effective thermal conductivity of MgH₂, which is one of the important parameters in the design of MgH₂-based hydrogen storage tanks. Cylindrical MgH₂ compacts containing up to 20 wt% ENG flakes with various average sizes (20, 50, 200, 350 and 1200 μm) were fabricated to measure the effective thermal conductivity of MgH₂–ENG mixtures. The radial direction effective thermal conductivity of the compacts was measured under a hydrogen atmosphere up to 70 bar. The conductivity was significantly enhanced by the addition of ENG flakes, reaching 9.3 W m⁻¹ K⁻¹ at 20 wt% ENG at 1 bar of hydrogen. It was observed that hydrogen pressure and the size of ENG flakes influenced the conductivity together with the amount of ENG. As hydrogen pressure increased up to 20 bar, the conductivity continued to increase. On the other hand, the conductivity very slowly increased above 20 bar, exhibiting a saturation tendency. It relatively rapidly increased with increasing average flake size up to 200 μm and then gradually decreased with further increasing size up to 1200 μm, exhibiting the maximum value at an average flake size of 200 μm. This trend might be determined by the competition between the thermal resistance at ENG/MgH₂ interfaces and the formation of conductive networks of ENG flakes.     

Enhanced Luminescence of Ca14Mg2Si8O28+δN4−δ:Eu2+Phosphors by Codoping Ce3+, Mn2+ for White LEDs and Their Energy‐Transfer Mechanism

The Eu²⁺, M‐codoped(M = Ce³⁺, Mn²⁺) phosphor powders were prepared by a solid‐state reaction. The addition of Ce³⁺ in the Eu²⁺ sites in partially nitridated bredigite‐structure phosphor(CMSN) remarkably enhances the luminescent intensity by ~180% through sensitized luminescence. Dual band emission was observed for Eu, Mn‐codoped CMSN through energy transfer from Eu²⁺ to Mn²⁺. Ce³⁺–Eu²⁺ and Eu²⁺–Mn²⁺ energy‐transfer mechanism was investigated through decay profile analysis using Inokuti–Hirayama model and energy‐transfer parameters are determined. Interaction mechanism was identified as dipole–dipole interaction. In addition, phosphor in glass plates was prepared using the phosphor and its feasibility in white LED application was studied and is presented.     

Synthesis of Sr2Nb3O10 nanosheets and their application for growth of thin film using an electrophoretic method

K(Sr₂Nb₃)O₁₀ (KSN) ceramic without the secondary phase was obtained from a KSN + 0.05K₂O specimen sintered at 1350°C. This ceramic was used as the precursor to synthesize Sr₂Nb₃O₁₀^? (SNO^?) nanosheets, because it has a pure KSN phase with a large (002) plane. The SNO^? nanosheets were deposited on a Pt/Ti/SiO₂/Si substrate using the electrophoresis method at room temperature, and heated at various temperatures to get rid of the organic defects. The crystalline SNO phase without organic defects was formed in film annealed at 600°C. However, when the annealing temperature exceeded 600°C, the Pt electrode became unstable, resulting in degradation of the SNO film. Good electric properties were obtained from the SNO film annealed at 600°C: dielectric constant of 70, dielectric loss of 0.017 at 1.0 MHz, leakage current density of 3.5×10^?8 A/cm² at 0.2 MV/cm, and a breakdown electric field of 0.25 MV/cm.     

Effect of homogeneous Al(OH)3 covered MWCNT addition on the thermal conductivity of Al2O3/epoxy-terminated poly(dimethylsiloxane) composites

Aluminum hydroxide covered multiwalled carbon nanotubes (A-MWCNTs) were synthesized as a conducting additive to alumina-epoxy-terminated poly(dimethylsiloxane). The measured diffusivity and calculated conductivity exhibited dissimilar behavior between several Al₂O₃ concentrations as a function of A-MWCNT loading, which correlated with the interface density and interconnectivity of the structures. The fabricated heterostructured A-MWCNT did not have a significant effect on the thermal conductivity of the composite because of phonon scattering at the interface. A small amount of A-MWCNT was feasible for establishment of a heat conductive percolating network with the greatest enhancement of thermal conductivity and diffusivity at an A-MWCNT loading of 1.0 and 2.0 wt%. Continuously increasing thermal transport properties were observed with the 49.1 vol.% Al₂O₃ loading which derived from a lower interface density nanowire and polymer matrix with enhanced interconnectivity.     

GaN nanorods grown on Si (111) substrates and exciton localization

We have investigated exciton localization in binary GaN nanorods using micro- and time-resolved photoluminescence measurements. The temperature dependence of the photoluminescence has been measured, and several phonon replicas have been observed at the lower energy side of the exciton bound to basal stacking faults (I ₁). By analyzing the Huang-Rhys parameters as a function of temperature, deduced from the phonon replica intensities, we have found that the excitons are strongly localized in the lower energy tails. The lifetimes of the I ₁ and I ₂ transitions were measured to be < 100 ps due to enhanced surface recombination.