Fundamental limits of high-efficiency silicon and compound semiconductor power amplifiers in 100-300 GHz bands

This paper reviews the requirements for future digital arrays in terms of power amplifier requirements for output power and efficiency and the device technologies that will realize future energy-efficient communication and sensing electronics for the upper millimeter-wave bands (100-300 GHz). Fundamental device technologies are reviewed to compare the needs for compound semiconductors and silicon processes. Power amplifier circuit design above 100 GHz is reviewed based on load line and matching element losses. We present recently presented class-A and class-B PAs based on a InP HBT process that have demonstrated record efficiency and power around 140 GHz while discussing circuit techniques that can be applied in a variety of integrated circuits.

Unlocking inclusive growth by linking micro assets to anchor institutions: The case of skilled overseas migrants and refugees and hospital jobs

This paper contributes to anchor institution, migrant and refugee integration, skills utilisation and inclusive growth debates. Via a pioneering innovative approach to inclusive urban development linking together physical infrastructure development and neighbourhood management approaches to urban regeneration, it explores the potential for micro assets within communities to be linked to macro assets of large spatially immobile anchor institutions. Through a case study, it draws on experience, and identifies transferable learning points, from a skills-matching element of a large European Union funded project in a superdiverse inner-city deprived neighbourhood in Birmingham, UK. In contrast to the typical emphasis of area-based employment initiatives on people with low skills, the skills-matching initiative focuses specifically on connecting skilled overseas migrants and refugees to skilled and highly skilled jobs in a large local hospital. It underlines the central role of local partnership working and highlights the role of skills utilisation, not merely skills development, in inclusive growth. The evidence suggests that three components underlie success in unlocking and catalysing links between micro assets and a macro asset to realise anchor institution potential: (1) institutional entrepreneurship, which provides the strategic buy-in from the anchor institution; (2) innovative entrepreneurship, which provides the delegated responsibility for implementation; and (3) vision and place leadership, which provides the strategy and resources to build the bridge between the macro asset and the local community to help realise inclusive growth.

The color appearance of three-dimensional, curved, transparent objects

Studies on the perceived color of transparent objects have elucidated potential mechanisms but have mainly focused on flat filters that overlay a flat background. However, studies with flat filters have not captured all aspects of physical transparency, such as caustics, specular reflections/highlights, and shadows. Here, we investigate color matching experiments with three-dimensional transparent objects for different matching stimuli: a uniform patch and a flat filter overlaying a variegated background. Two different instructions were given to observers: change the color of the matching stimulus until it has the same color as the transparent object (for the patch and flat filter) or until it has the same color as the dye that was used to tint the transparent object (for the patch). Regardless of instruction or matching element, observers match the mean chromaticity of the glass object, but the luminance of matches depends on the backgrounds of the test image and the matching element, indicating that a color constancy-esque discounting operation is at work. We applied three models from flat filter studies to see if they generalize to our stimuli: the convergence model and the ratio of either the means (RMC) or standard deviations (RSD) of cone excitations. The convergence model does not generalize to our stimuli, but the RMC generalizes to a wider range of stimuli than the RSD. However, there is an edge case where RMC also breaks down and there may be additional features that trade-off with RMC when observers match the color of thick, curved transparent objects.

Quasi-self-complementary ultra-wideband antenna with band rejection characteristics

This article presents a compact novel quasi-self-complementary semi-octagonal-shaped antenna for ultra-wideband (UWB) application. The proposed novel structure is fed by a microstrip line where different rectangular truncation is etched to the ground plane as an impedance matching element, which results for much wider impedance bandwidth (VSWR<2) from 2.9 to 20 GHz. In order to obtain band-notched characteristics at 5.5 GHz, an open-ended, quarter wavelength, spiral-shaped stub is introduced in the vicinity of the truncated part of the ground plane. An equivalent circuit model is adopted to investigate the band rejection characteristics of the ground plane stub. Sharpness of the rejection band can be controlled by maintaining the gap between stub resonator and the slotted periphery of ground plane. The proposed antenna design is validated by experimental measurements.

A Hybrid Dense Matching Method for Satellite Images

To solve the dense matching problem for stereoscopic satellite images, a hybrid matching scheme integrating multiple methods is proposed. This scheme utilizes two types of matching element including grid points and edge points. First the geometrically constrained cross-correlation (GC3) method is used to extract matching grids. While in less textured regions using GC3 cannot get sufficient matching grids, so the local affine transformation is used to establish the region correspondence, and more matching grids can be generated. Edges are extracted by Canny operator and approximated with a series of straight edge segments using a polygon approximation. Based on these approximated edges, edge correspondences between image pairs are established using GC3. This scheme fuses the region based and the feature based matching methods. It has been tested with real satellite images and the results demonstrate its accuracy and efficiency.