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Practices and attitudes towards early user involvement in information symbol design process: an implication for teaching
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Investigation of low-frequency noise in van der Waals epitaxies
No full textWe report the growth of high quality SnS van der Waals epitaxies (vdWEs) on mica by molecular beam epitaxy (MBE). Record low rocking curve FWHM for the SnS (001) and SnSe (001) epilayers were observed. Detailed investigations of the film morphology indicate layer-by-layer growth mode expected for 2D layered structure. The characteristic structural symmetry of the mica surface leads to the nucleation of crystallites with different lateral orientations. This results in high concentration of grain boundaries and high level of low-frequency excess noise. We investigated the growth mechanisms of the vdWEs and suggested a novel growth technique in which a SnSe buffer layer is utilized to reduce the concentration of the grain boundary. The idea is tested experimentally and significant reduction in the low-frequency noise is observed suggesting the use of the buffer layer had resulted in the reduction in the possible growth orientations of the top SnS epilayer and thereby reducing the grain boundary concentration
Tradition and future: VET in Hong Kong, a new perspective
Get PDFAs the Hong Kong economy had experienced several rounds of structural changes during the past 30 years, the vocational education and training (VET) systems in Hong Kong had also undergone much transformation throughout the same period. In particular, modern VET in Hong Kong, which started to take root in mid-2000s, has gradually evolved through a series of well-planned, pro-active and concerted efforts masterminded by the Vocational Training Council (VTC) of Hong Kong.
VTC turned out a quarter of a million trainees per year to meet industries’ need at the craftsman, technician and technologist level. Riding on a conceptual framework of VET principles, VTC aims to solve the imminent labour mismatch problem, enhance Hong Kong’s manpower competitiveness as well as extend its presence as a VET pioneer/leader in the regional context.
Modern VET in Hong Kong operates hypothetically on three structural building blocks, viz., the system of qualification standards, the collaborated model of VET assessment and the integrated model of VET delivery. The system of qualification standards mainly comprises the Qualification Framework (QF) benchmarked against international standards and the Specifications of Competency Standard developed and recognized by local industries. The collaborative VET model is actualized through various initiatives such as the “oneexamination oneexamination- multiple-certifications” scheme as well as the “one-course-dual-qualifications” system, which enable practitioners’ qualifications to be recognized and certified in Mainland China and overseas hence realizing portability of qualifications at both national and international level.
The integrated VET model combines on-the-job training at the workplace and off-the-job vocational education at the campus. Together with the process of “workplace recognition”, a trainee undergoes an “integrated” package of training and attains one total and integrated qualification under an increasingly popular “earn and learn” mode of VET. It helps trainees to master the required practical and vocational competencies through workplace training effectively while at the same time acquire the corresponding qualifications recognizable by the industry
A Method to Deal with Prospective Risks at Home in Robotic Observations by Using a Brain-Inspired Model
No full textHome robotics is a continuously growing field in academic research as well as commercial market. People are becoming more interested in advanced intelligent robots that can do housework and take care of children and elderly. A brain-inspired intelligent system is a possible solution to make the robot capable of learning and predicting risks at home. In order to solve difficult problems such as ambiguous situations and unclear causality, we propose a robotic system inspired from human working memory functions, which consists of an Event Map for storing observed information, and a Causality Map for representing causal relationships through supervised learning. The two maps couple together to enable the robot to evaluate various situations based on the appropriate context. More importantly, the Causality Map takes into account the dynamical aspects of physical attributes (e.g. the decreasing temperature of a hot pot). Our case studies showed that this is a satisfactory solution for predicting many risky situations at home
Spiking neural network model for memorizing sequences with forward and backward recall
No full textWe present an oscillatory network of conductance based spiking neurons of Hodgkin–Huxley type as a model of memory storage and retrieval of sequences of events (or objects). The model is inspired by psychological and neurobiological evidence on sequential memories. The building block of the model is an oscillatory module which contains excitatory and inhibitory neurons with all-to-all connections. The connection architecture comprises two layers. A lower layer represents consecutive events during their storage and recall. This layer is composed of oscillatory modules. Plastic excitatory connections between the modules are implemented using an STDP type learning rule for sequential storage. Excitatory neurons in the upper layer project star-like modifiable connections toward the excitatory lower layer neurons. These neurons in the upper layer are used to tag sequences of events represented in the lower layer. Computer simulations demonstrate good performance of the model including difficult cases when different sequences contain overlapping events. We show that the model with STDP type or anti-STDP type learning rules can be applied for the simulation of forward and backward replay of neural spikes respectively
Synthesis, characterization, and photophysical studies of neutral rhenium(I) luminophores with anionic isocyanoborate ligands
No full textKinetic models and process parameters for ultrasound-assisted extraction of water-soluble components and polysaccharides from a medicinal fungus
No full textThis study was on the kinetics and process parameters for ultrasound-assisted extraction (UAE) of water-soluble components and polysaccharides (PS) from the dry mycelium of a medicinal fungus, Cordyceps sinensis Cs-HK1. Four process variables (factors) were evaluated at different levels, ultrasound intensity (2.44–44.1W/cm2), temperature (40–70°C), solid particle size (156.5–750μm), and solid-to-liquid ratio (1/30–1/70g/mL). The experimental data of yields versus time in most cases were fitted closely to two empirical kinetic models for solid–liquid extraction, parabolic diffusion equation (y=yo+y1t1/2) and power law (y=βtn) with high correlation coefficients (R2) of 0.95–0.99 for total extract yield, and 0.90–0.96 for PS yield. The PS yield was increased more significantly than the total extract yield with the ultrasound intensity. Reducing the particle size and increasing the extraction temperature led to a higher yield and extraction rate; increasing the solid-to-liquid ratio (or decreasing the liquid volume) increased the PS yield and extraction rate but had little influence on the total extract. Significant correlations were found between extraction rate (dy/dt) and ultrasound power density (P/V), and between extract yield (y) and energy density (Pt/V). The kinetic and process parameters are useful for rational design and efficient operation of UAE processes
Synthesis and photocatalytic activity of boron and fluorine codoped TiO2 nanosheets with reactive facets
No full textIn this study, TiO2 nanosheets codoped with boron and fluorine were prepared by a one-pot hydrothermal method and investigated for photocatalytic dye degradation and disinfection. The as-prepared TiO2 materials were characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). The results indicate that the as-prepared TiO2 are of nanosheet morphology with anatase phase. The best degradation performance was obtained for square TiO2 nanosheet sized 10nm long on the side and 2.5nm thick. Methylene blue was degraded by 95% in concentration under visible light irradiation for 5h. In addition, TiO2 nanosheets showed good stability after eight cycles of photocatalytic testing. The disinfection study implied that B,F-codoped TiO2 nanosheets could effectively inactivate bacteria within 15min under visible light. The performance of B,F-codoped TiO2 nanosheets is clearly much better than that of F-doped TiO2 nanosheets and commercial Degussa P25