Enhanced geometrical superresolved imaging with moving binary random mask

In this paper, we address the geometrical resolution limitation of an imaging sensor caused by the size of its pixels yielding insufficient spatial sampling of the image. The spatial blurring that is caused due to inadequate sampling can be resolved by placing a two-dimensional binary random mask in an intermediate image plane and shifting it along one direction while keeping the sensor as well as all other optical components fixed. Out of the set of images that are captured, a high resolution image can be decoded. In addition, this approach allows improved robustness to spatial noise.     

Training a network with ternary weights using the CHIR algorithm

A modification of the binary weight CHIR algorithm is presented, whereby a zero state is added to the possible binary weight states. This method allows solutions with reduced connectivity to be obtained, by offering disconnections in addition to the excitatory and inhibitory connections. The algorithm has been examined via extensive computer simulations for the restricted cases of parity, symmetry, and teacher problems, which show convergence rates similar to those presented for the binary CHIR2 algorithm, but with reduced connectivity. Moreover, this method expands the set of problems solvable via the binary weight network configuration with no additional parameter requirements.     

All-optical wavelength conversion using a pulse reformatting optical filter

We introduce a general concept for the design of all-optical wavelength converters with pulse reformatting functionality. The novel wavelength converters are based on a single semiconductor optical amplifier followed by an optical filter. A microelectromechanical system-based realization is shown and simultaneous 40 Gb/s wavelength conversion, switching and signal format conversion is demonstrated. The new pulse reformatting optical filter device outperforms current schemes with respect to input-power requirements, input-power dynamic range and signal quality.     

Swelling and hygroelasticiiy of polymeric composites

Investigated are the swelling and hygroelasticity of a unidirectional glass fiber-reinforced epoxy composite subjected to boiling water for 24 hrs. By analogy with thermoelasticity, a coefficient of hygroelasticity is defined and shown to be predictable from the coefficients of the constituent materials by Schapery's equations. A mechanism for water penetration into the composite which combines capillarity and diffusion is proposed on the basis of the results of the water take-up as a function of the composite specimen width (fiber length).     

Exceptional enhancement of ductility and toughness in poly(vinylidene fluoride)/carbon nanotubes composites

The reinforcement of mechanical properties of polymeric materials is often important for widening their applications; however, it remains a technical challenge to effectively increase toughness without degrading stiffness and strength of the polymers. In this work, by a facile methodology combining solution mixing and melt blending, poly(vinylidene fluoride)/multi‐walled carbon nanotubes (PVDF/MWCNTs) composite with exceptionally enhanced ductility and toughness are prepared. With only 0.2 wt % CNT loading, the elongation at break has increased from originally 138% to almost 500%, while toughness improved by as much as 386%, without compromising the stiffness and strength. Note that raw CNTs are directly dispersed in the matrix without any surface modification. In order to elucidate this novel enhancement of ductility of PVDF/MWCNTs composites, we carried out detailed analyses based on results from ultra‐small‐angle X‐ray scattering (USAXS), cryo‐fractured surface morphology, differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). It is proposed that the enhanced ductility are contributed by a synergistic combination of “void pinning effect” of CNT, as well as the formation of γ phase polymorph as the interphase in the PVDF/CNTs composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43610.     

The effect of transcrystallinity on the transverse mechanical properties of single-polymer polyethylene composites

The microstructure of polyethylene (PE)/PE composites, consisting of the high-density PE (HDPE) matrix and ultrahigh molecular-weight PE (UHMWPE) fibers, was investigated. Single-fiber composites were prepared and analyzed in a hot-stage crystallization unit attached to a polarizing microscope, aiming to find out how the conditions of crystallization affected the transcrystallinity (tc) growth at the fiber-matrix interface. Thermal treatments leading to two extreme microstructures, of either maximum or minimum thickness of the transcrystalline zone, were sought. It was found that a uniform transcrystalline layer was developed on the UHMWPE fiber from the HDPE melt under isothermal conditions, whereas rapid cooling from the melt prevented the generation of tc. The mechanical properties of unidirectional composite laminae either with or without the transcrystalline zone were measured. A comparison of the transverse strength predicted by theoretical models with the experimental values revealed good interfacial adhesion in the PE/PE system. It was shown that the tc growth had a negligible effect on the composite mechanical properties in the longitudinal direction, whereas it resulted in a 50% decrease of the transverse tensile strength and strain to failure. Scanning electron microscopy attributed that observation to premature brittle failure at tc/tc contact regions. © 1995 John Wiley & Sons, Inc.     

Failure modes and fracture mechanisms in flexure of Kevlar-epoxy composites

The results of testing in three-point bending of aramid fibre-reinforced epoxy composites are described. This loading mode has been chosen in order to increase the variety of failure modes and of fracture mechanisms. The main failure modes observed are tensile and delamination, with a transition at a fibre volume fraction of about 46%. This mode transition is detectable by monitoring various mechanical properties and acoustic emission data against the fibre volume fraction. The tensile mode comprises a fracture mechanism of fibre splitting and pull-out and the delamination comprises fibre bending, tearing off of fibre skin and shearing of individual filaments. Other effects such as the shifting of the neutral axis and the compressive failure at the compression side are also reported.     

Compact all-optical bypass-exchange switch

An electronically or optically addressed compact optical bypass-exchange switch is investigated and experimentally demonstrated.The switch is polarization based and consists of a controllable λ/2 platesandwiched between two polarizing beam displacers. The input and the output signals propagate normal to the switching array, which makes the switch extremely attractive for cascading switching arrays, as found in multistage interconnect networks. A complete, all-optical interconnection network is suggested.