Ultimately short ballistic vertical graphene Josephson junctions

Much efforts have been made for the realization of hybrid Josephson junctions incorporating various materials for the fundamental studies of exotic physical phenomena as well as the applications to superconducting quantum devices. Nonetheless, the efforts have been hindered by the diffusive nature of the conducting channels and interfaces. To overcome the obstacles, we vertically sandwiched a cleaved graphene monoatomic layer as the normal-conducting spacer between superconducting electrodes. The atomically thin single-crystalline graphene layer serves as an ultimately short conducting channel, with highly transparent interfaces with superconductors. In particular, we show the strong Josephson coupling reaching the theoretical limit, the convex-shaped temperature dependence of the Josephson critical current and the exceptionally skewed phase dependence of the Josephson current; all demonstrate the bona fide short and ballistic Josephson nature. This vertical stacking scheme for extremely thin transparent spacers would open a new pathway for exploring the exotic coherence phenomena occurring on an atomic scale.open113435sciescopu

System-level key performance indicators for building performance evaluation

Quantifying building energy performance through the development and use of key performance indicators (KPIs) is an essential step in achieving energy saving goals in both new and existing buildings. Current methods used to evaluate improvements, however, are not well represented at the system-level (e.g., lighting, plug-loads, HVAC, service water heating). Instead, they are typically only either measured at the whole building level (e.g., energy use intensity) or at the equipment level (e.g., chiller efficiency coefficient of performance (COP)) with limited insights for benchmarking and diagnosing deviations in performance of aggregated equipment that delivers a specific service to a building (e.g., space heating, lighting). The increasing installation of sensors and meters in buildings makes the evaluation of building performance at the system level more feasible through improved data collection. Leveraging this opportunity, this study introduces a set of system-level KPIs, which cover four major end-use systems in buildings: lighting, MELs (Miscellaneous Electric Loads, aka plug loads), HVAC (heating, ventilation, and air-conditioning), and SWH (service water heating), and their eleven subsystems. The system KPIs are formulated in a new context to represent various types of performance, including energy use, peak demand, load shape, occupant thermal comfort and visual comfort, ventilation, and water use. This paper also presents a database of system KPIs using the EnergyPlus simulation results of 16 USDOE prototype commercial building models across four vintages and five climate zones. These system KPIs, although originally developed for office buildings, can be applied to other building types with some adjustment or extension. Potential applications of system KPIs for system performance benchmarking and diagnostics, code compliance, and measurement and verification are discussed

Using the simple peel test to measure the adhesive fracture energy, Ga

The adhesive fracture energy of structural adhesive joints may be readily ascertained from linear-elastic fracture-mechanics (LEFM) methods, and indeed an ISO Test Method (ISO 25217: 2009) now exists for the LEFM Mode I value, Gc, as a result of the efforts of the European Structural Integrity Society (ESIS) ‘TC4 Committee’ [1,2]. These LEFM test methods involve the preparation and testing of adhesively-bonded double-cantilever beam (DCB) and tapered double-cantilever beam (TDCB) specimens [3,4]. Notwithstanding the sound and reproducible results that may be obtained from such methods, the LEFM test specimens are relatively complex and expensive to make and test, and many industries would far prefer to deduce the value of the adhesive fracture energy from the very common and widely-used ‘peel test’. (In the present paper, for clarity, the adhesive fracture energy is termed GA when deduced from a peel test.) Indeed, the peel test is an attractive test method to assess the fracture performance of a wide range of structural adhesive joints and flexible laminates. However, although it is a relatively simple test to undertake, it is often a complex test to analyse and thus obtain a characteristic measure of the toughness of the adhesive joint, or laminate

Strategies for optimising domestic solid waste management systems in urban areas of Australia and South Korea

University of Technology, Sydney. Faculty of Engineering.In today’s world, with rapidly developing technologies and booming population, solid waste management has become a major concern. In general, awareness of this problem could lead to the development of improved pollution control technologies and rigorous policies for solid waste handling systems and disposal, in order to minimise the environmental impacts of this waste. In addition, policy-makers need to develop and implement effective municipal solid waste management strategies, taking into account all economic, technical, and environmental objectives and factors. As the population continues to increase in both Australia and South Korea, the need for strategies to optimise municipal solid waste systems and manage waste is becoming more urgent. It is important to understand that solid waste management is a complex task, which depends as much upon organisation and cooperation between households, communities, private enterprises and government at all levels as it does upon recycling and disposal systems. A conventional view is that either private or public management is more efficient for managing municipal solid waste systems, irrespective of the nature of the resource, or the socio-economic situation of the people. However, because many local governments lack the appropriate financial, technical and human resources, they are neither able nor willing to manage these systems. Industrialised countries such as Australia and South Korea produce millions of tonnes of municipal solid waste every year, which deplete the world’s natural resources and have negative consequences for the environment. In recognition of this problematic global trend, the question of environmental protection for the world’s sustainable development through solid waste management systems has been given special attention by many countries, including Australia and South Korea. This study has sought to provide the cities of Sydney and Seoul with tools that will enable them to evaluate the environmental and economic performance of the various elements of their existing or proposed waste management systems. The tools are based on the best information publicly available at the present time, with a commitment to revise this information periodically to ensure that it is up-to-date. The tools are intended as guides only; they do not prescribe the best system for each city. The determination of the best system for a community must take into account several factors, including social and political considerations. A survey was designed and conducted with the purpose of collecting information on the attitudes of the residents of Sydney and Seoul about municipal solid waste management, how they perceive the current programs of their respective cities in terms of collection, processing and disposal, and how they believe the waste management programs of their cities could be improved in terms of decreasing the amounts of waste generated and effectively managing the collected wastes. The researcher applied the second version of the White model, the Integrated Municipal Waste (IMW-2) model. The application of the MSW analysis to the two different cities provided an interesting comparison of economic cost, environmental cost and disposal cost. For example, the cost of disposal is quite similar between the two cities. The result does not clearly confirm the environmental superiority of the incineration over the landfill. However, if an incineration facility is introduced in Sydney, an increase of the economic cost of the system will occur. Even though these comparisons are not 100% rigorous, this analysis is still useful for giving some estimation of future MSW management strategies. The study has used a structured focused comparison to investigate the prevailing waste management programs of Sydney and Seoul and determine the strengths, weaknesses, opportunities and threats in each, in order to develop a waste management model that can be utilised in each city. To achieve optimal results, solid waste management programs must be based on the life-cycle philosophy, filling in the gaps to assess the economic affordability of waste systems, to evaluate the environmental effects involving a product or process, to implement ways to improve or lessen these impacts, and to call for greater public participation in the solid waste management program

COMPUTER-GENERATED HOLOGRAM ETCHED IN GAAS FOR OPTICAL INTERCONNECTION OF VLSI CIRCUITS

By integrating, on a wafer plane, GaAs semiconductor optoelectronic modulators and detectors with computer-generated holograms between then, the potential for in-plane interconnections is proposed. We report the fabrication and characterisation of a binary-phase relief hologram etched in a GaAs wafer using an averaged Fresnel zone plate design to focus light to 2 x 2 spots for array interconnection. Efficiencies of 28% for this design of binary CGH etched in GaAs have been achieved, close to the theoretical maximum

Cug2 is essential for normal mitotic control and CNS development in zebrafish.

Background: We recently identified a novel oncogene, Cancer-upregulated gene 2 (CUG2), which is essential for kinetochore formation and promotes tumorigenesis in mammalian cells. However, the in vivo function of CUG2 has not been studied in animal models. Results: To study the function of CUG2 in vivo, we isolated a zebrafish homologue that is expressed specifically in the proliferating cells of the central nervous system (CNS). Morpholino-mediated knockdown of cug2 resulted in apoptosis throughout the CNS and the development of neurodegenerative phenotypes. In addition, cug2-deficient embryos contained mitotically arrested cells displaying abnormal spindle formation and chromosome misalignment in the neural plate. Conclusions: Therefore, our findings suggest that Cug2 is required for normal mitosis during early neurogenesis and has functions in neuronal cell maintenance, thus demonstrating that the cug2 deficient embryos may provide a model system for human neurodegenerative disorders

Complete gate control of supercurrent in graphene p-n junctions

In a conventional Josephson junction of graphene, the supercurrent is not turned off even at the charge neutrality point, impeding further development of superconducting quantum information devices based on graphene. Here we fabricate bipolar Josephson junctions of graphene, in which a p-n potential barrier is formed in graphene with two closely spaced superconducting contacts, and realize supercurrent ON/OFF states using electrostatic gating only. The bipolar Josephson junctions of graphene also show fully gate-driven macroscopic quantum tunnelling behaviour of Josephson phase particles in a potential well, where the confinement energy is gate tuneable. We suggest that the supercurrent OFF state is mainly caused by a supercurrent dephasing mechanism due to a random pseudomagnetic field generated by ripples in graphene, in sharp contrast to other nanohybrid Josephson junctions. Our study may pave the way for the development of new gate-tuneable superconducting quantum information devices.open114344sciescopu

Effects of floor impact noise on psychophysiological responses

The present study analysed the effects of floor impact noise on humans using both psychological and physiological methods. Floor impact noises caused by a standard impact source (i.e. impact ball) and five real impact sources (e.g., human footsteps and dropped objects) were recorded as sound stimuli. During the laboratory experiments, two factors that impact psychophysiological responses were considered: (1) types of impact sources (standard or real sources) and (2) the levels of floor impact noise ranging from 31.5 to 63 dBA in terms of A-weighted maximum sound pressure level (LAFmax). Twenty-one normal-hearing subjects were then asked to judge the noticeability and annoyance caused by the floor impact noises. Meanwhile, the subjects' physiological responses (heart rate: HR, electrodermal activity: EDA, and respiration rate: RR) were monitored throughout the experiments. Noise annoyance and noticeability increased with increases in noise levels, the impact ball resulted in higher noticeability and annoyance ratings than real sources. All physiological measures varied significantly with noise exposure; HR decreased, whereas EDA and RR increased. The results show that the physiological responses were not affected by the type of noise source. In addition, the noise level was found to be significantly related to EDA and RR changes, whereas the relationship between the noise level and HR was not found to be significant

Effects of non-acoustic factors on annoyance caused by floor impact sounds: A structural equation analysis

Previous research studies have addressed the relevance of non-acoustic factors in the perception of noise. However, the majority of these studies have focused on environmental noise, such as road traffic, railway and aircraft noises, and no attempt has been made to investigate the impact of building noises. In this paper, a conceptual model which explains the annoyance caused by floor impact sounds in apartment buildings was proposed based on previous findings and is subject to empirical testing. Online and paper questionnaire surveys were conducted in Korea and the questionnaire included questions designed to assess the impact of non-acoustic factors on annoyance caused by floor impact sounds, such as noise sensitivity and neighbourhood satisfaction. The structural equation model developed from the survey indicated that a negative relationship with neighbours resulted in greater annoyance, while a greater sensitivity to noise leaded to a greater perception of disturbance from noise. The various types of noises also produced different effects on relationship between noise annoyance and relationship with neighbours