341 research outputs found
Stream-based Hebbian Eigenfilter for real-time neuronal spike discrimination
No full textBackground Principal component analysis (PCA) has been widely employed for automatic neuronal spike sorting. Calculating principal components (PCs) is computationally expensive, and requires complex numerical operations and large memory resources. Substantial hardware resources are therefore needed for hardware implementations of PCA. General Hebbian algorithm (GHA) has been proposed for calculating PCs of neuronal spikes in our previous work, which eliminates the needs of computationally expensive covariance analysis and eigenvalue decomposition in conventional PCA algorithms. However, large memory resources are still inherently required for storing a large volume of aligned spikes for training PCs. The large size memory will consume large hardware resources and contribute significant power dissipation, which make GHA difficult to be implemented in portable or implantable multi-channel recording micro-systems. Method In this paper, we present a new algorithm for PCA-based spike sorting based on GHA, namely stream-based Hebbian eigenfilter, which eliminates the inherent memory requirements of GHA while keeping the accuracy of spike sorting by utilizing the pseudo-stationarity of neuronal spikes. Because of the reduction of large hardware storage requirements, the proposed algorithm can lead to ultra-low hardware resources and power consumption of hardware implementations, which is critical for the future multi-channel micro-systems. Both clinical and synthetic neural recording data sets were employed for evaluating the accuracy of the stream-based Hebbian eigenfilter. The performance of spike sorting using stream-based eigenfilter and the computational complexity of the eigenfilter were rigorously evaluated and compared with conventional PCA algorithms. Field programmable logic arrays (FPGAs) were employed to implement the proposed algorithm, evaluate the hardware implementations and demonstrate the reduction in both power consumption and hardware memories achieved by the streaming computing Results and discussion Results demonstrate that the stream-based eigenfilter can achieve the same accuracy and is 10 times more computationally efficient when compared with conventional PCA algorithms. Hardware evaluations show that 90.3% logic resources, 95.1% power consumption and 86.8% computing latency can be reduced by the stream-based eigenfilter when compared with PCA hardware. By utilizing the streaming method, 92% memory resources and 67% power consumption can be saved when compared with the direct implementation of GHA. Conclusion Stream-based Hebbian eigenfilter presents a novel approach to enable real-time spike sorting with reduced computational complexity and hardware costs. This new design can be further utilized for multi-channel neuro-physiological experiments or chronic implants.Engineering and Physical Sciences Research Council (EPSRC grant EP/E044662/1)National Natural Science Foundation (China) ( grant 61006021)National Natural Science Foundation (China) (grant 4112029)National Institutes of Health (U.S.) (Grant HL067966)National Institutes of Health (U.S.) (Grant RR028241
Use of accelerated carbonation technique to enhance the properties of recycled aggregate concrete
No full textAbstract only. - In Hong Kong, huge quantities of construction and demolition (C&D) wastes (57,000 tonper- day) are produced representing the largest fraction of the total solid waste stream. The disposal of the wastes has become a severe social and environmental problem in the territory. Government sources have indicated that there are acute shortages of both public filling areas (reclamation sites) and landfill space in Hong Kong. Hong Kong’s three mega landfills are expected to be full within 5-6 years’ time. The possibility of reducing and recycling these wastes is thus of prime importance. The Hong Kong Polytechnic University has been conducting research on methods to recycle construction waste. The potential applications of the recycled materials are in road pavements, concrete, concrete blocks and mortars. Some of the developed techniques have been commercially utilized in industry. This presentation summarizes the major findings of the research conducted, and introduces some case studies on utilizing accelerated carbonation technique to enhance the properties of recycled aggregate concrete In recent years, adopting the accelerated carbonation technique to improve the quality of recycled concrete wastes as well as to capture and store CO2 has been investigated by a number of researchers including our group at PolyU. The potential CO2 capture ability of recycled concrete aggregates (RCAs) was related to the carbonation conditions and the characteristics of RCAs. It was found that a moderate relative humidity, a CO2 concentration higher than 10%, a slight positive pressure or a gas flow rate of > 5 L/min were optimal to accelerate the RCAs carbonation. The properties of RCAs were improved after the carbonation treatment. The reduction of water absorption was up to 16.7%. There was about 4.0% increase of 10% fine value and a 26% reduction of crushing value. This resulted in performance enhancement of the new concrete prepared with the carbonated RCAs, especially an obvious increase of the mechanical strengths and an even more significant improvement of durability properties. In addition, the replacement percentage of natural aggregates by the carbonated RCAs can be increased to 60% with an insignificant reduction in the mechanical properties of the new concrete. Additionally, the potential utilization of fresh concrete slurry waste (CSW), which is sourced from dewatered solid cement residues after washing out over-ordered/rejected fresh concrete and concrete trucks in concrete batching plants, has been investigated. Due to its rich calcium-silicate content and cementitious feature, it was considered as a cementitious paste as well as a CO2 capture medium to produce new products. Subjecting to accelerated carbonation, rapid initial strength development and lower drying shrinkage for the prepared concrete mixture were achieved. Moreover, the production of the concrete mixtures for partition wall blocks using the developed technique can be considered as carbon neutral
Real-time FPGA-based multichannel spike sorting using Hebbian eigenfilters
No full textReal-time multichannel neuronal signal recording has spawned broad applications in neuro-prostheses and neuro-rehabilitation. Detecting and discriminating neuronal spikes from multiple spike trains in real-time require significant computational efforts and present major challenges for hardware design in terms of hardware area and power consumption. This paper presents a Hebbian eigenfilter spike sorting algorithm, in which principal components analysis (PCA) is conducted through Hebbian learning. The eigenfilter eliminates the need of computationally expensive covariance analysis and eigenvalue decomposition in traditional PCA algorithms and, most importantly, is amenable to low cost hardware implementation. Scalable and efficient hardware architectures for real-time multichannel spike sorting are also presented. In addition, folding techniques for hardware sharing are proposed for better utilization of computing resources among multiple channels. The throughput, accuracy and power consumption of our Hebbian eigenfilter are thoroughly evaluated through synthetic and real spike trains. The proposed Hebbian eigenfilter technique enables real-time multichannel spike sorting, and leads the way towards the next generation of motor and cognitive neuro-prosthetic devices
Comparing the effectiveness of physical exercise intervention and melatonin supplement in improving sleep quality in children with ASD
No full textPurpose: previous studies have demonstrated that physical exercise can modulate the endogenous melatonin level in children with autism spectrum disorder (ASD) and improve their sleep quality. However, it remains unclear whether physical exercise or melatonin supplement, or a combination of both, is more effective in improving sleep quality in this population. The purpose of this study is to answer this research question by comparing the effectiveness of three types of interventions (physical exercise vs. melatonin supplement or a combination of both) in improving sleep quality in children with ASD.Methods: sixty-two (62) children diagnosed with ASD were randomly assigned to one of four groups: cycling (n = 18), melatonin supplement (n = 14), a combination of both (n = 12), and placebo control group (n = 18). Four (4) sleep parameters (sleep efficiency, sleep onset latency, sleep duration, and wake after sleep onset) were assessed.Results: the results revealed a significant improvement in sleep efficiency, sleep onset latency, and sleep duration in all of the interventions, but not in the placebo control group. However, no significant group differences were found among the interventions (ps >.05).Conclusion: our findings suggest similar effectiveness of physical exercise and melatonin supplementation in improving sleep quality in children with ASD.</p
Upcycling Waste for a Carbon-Neutral Tomorrow
No full textIn English, with English and Chinese subtitles202312 bcwhVersion of RecordPublished103515Publisher permissio
Design issues of using prefabrication in Hong Kong building construction
No full textPrefabrication techniques have been adopted for the last two decades in public housing projects in Hong Kong, but the use of prefabrication in the private sector was encouraged only after the implementation of the Joint Practices Notes which promote its use. Although previous studies acknowledge the environmental benefits of using prefabrication, only a few studies have addressed sustainable design concepts (closed‐loop) in the adoption of precast construction. A questionnaire survey was administered to experienced Hong Kong construction professionals, and case studies of recently completed building projects were compiled to ascertain the use of prefabrication with reference to life cycle approach. The findings revealed that prefabrication, combined with modular design and standard components, saved time and construction/design costs, as buildings systems were used across projects. However, in some projects, specific site conditions restricted the use of similar prefabricated building systems across projects. Surprisingly only a few participants addressed life cycle design concepts such as design for deconstruction when adopting precast construction. Also, although it is common knowledge that flexible and demountable prefabricated building systems would result in efficient use of resources, their use is seldom practised in Hong Kong.Hong Kong, life cycle design, prefabrication, precast concrete, sustainable construction,
Utilization of recycled glass derived from cathode ray tube glass as fine aggregate in cement mortar
No full textRapid advances in the electronic industry led to an excessive amount of early disposal of older electronic devices such as computer monitors and old televisions (TV) before the end of their useful life. The management of cathode ray tubes (CRT), which have been a key component in computer monitors and TV sets, has become a major environmental problem worldwide. Therefore, there is a pressing need to develop sustainable alternative methods to manage hazardous CRT glass waste. This study assesses the feasibility of utilizing CRT glass as a substitute for natural aggregates in cement mortar. The CRT glass investigated was an acid-washed funnel glass of dismantled CRT from computer monitors and old TV sets. The mechanical properties of mortar mixes containing 0%, 25%, 50%, 75% and 100% of CRT glass were investigated. The potential of the alkali-silica reaction (ASR) and leachability of lead were also evaluated. The results confirmed that the properties of the mortar mixes prepared with CRT glass was similar to that of the control mortar using sand as fine aggregate, and displayed innocuous behaviour in the ASR expansion test. Incorporating CRT glass in cement mortar successfully prevented the leaching of lead. We conclude that it is feasible to utilize CRT glass in cement mortar production.Department of Civil and Environmental Engineerin
A comparative study on the properties of the mortar with the cathode ray tube funnel glass sand at different treatment methods
No full textComparative studies on the effects of sewage sludge ash and fly ash on cement hydration and properties of cement mortars
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