Abstract: In this paper, we propose to extend SPARQL functions for querying Industry Foundation Classes (IFC) building data. The official IFC documentation and BIM requirement checking use cases are used to drive the development of the proposed functionality. By extending these functions, we aim to (1) simplify writing queries and (2) retrieve useful information implied in 3D geometry data according to requirement checking use cases. Extended functions are modelled as RDF vocabularies and classified into groups for further extensions. We combine declarative rules with procedural programming to implement extended functions. Realistic requirement checking scenarios are used to evaluate and demonstrate the…effectiveness of this approach and indicate query performance. Compared with query techniques developed in the conventional Building Information Modeling domain, we show the added value of such approach by providing an application example of querying building and regulatory data, where spatial and logic reasoning can be applied and data from multiple sources are required. Based on the implementation and evaluation work, we discuss the advantages and applicability of this approach, current issues and future challenges.
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Keywords: BimSPARQL, IFC, ifcOWL, SPARQL, function
DOI: 10.3233/SW-180297
Citation: Semantic Web,
vol. 9, no. 6, pp. 829-855, 2018
Abstract: This paper presents a three-link direct drive robot arm for wafer handling application. This robot arm is directly driven by three permanent magnet synchronous motors which are designed with flat structures and large rated torques. The mechanical structures of the presented robot arm and the PM motors are introduced and their dynamic models are derived. The frequency responses obtained from experimental tests reveal serious coupling effect of the system. A decoupling method based on computed torque control is proposed and the test results validate the effectiveness of this method. Robust SISO controllers are developed to control the PM motors after…the decoupling. The experimental results demonstrate satisfying dynamic, settling and static performances with the proposed robust decoupling control.
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Abstract: A permanent magnet synchronous motor and an induction motor both having dual air-gap, axial flux configurations have been designed. Both of these two type motors have twin stators and double-side single rotor that is sandwiched between these two stators. On the double surfaces of both disk-type rotors, the permanent magnets are mounted and copper rotor-bars are filled in the slots respectively. The mathematical models of these two type motors have been derived, and the performances of the motors are compared mathematically. Three-dimensional finite element method (FEM) is implemented to analyze the characteristics of these motors and make comparison between them.…The analysis results support the feasibility of the motor structures and prove that the PM motor has higher torque density and efficiency when the same dimension is assigned to both motors.
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Keywords: Axial flux motor, axial flux PM motor, axial flux induction motor, 3D FEM analysis
Abstract: This paper presents a nonlinear iterative magnetic equivalent circuit (MEC) model for a novel counter-rotation dual-rotor axial flux permanent magnet synchronous machine (CRDR-AFPMSM). The proposed machine mainly consists of two rotors with opposite rotation directions, two sets of concentrated windings and a stator core sandwiched in between the two rotors. The model takes into account of the nonlinear characteristics of the saturable permeance in the stator core, and the permeance matrix is updated by an iterative procedure to accurately illustrate its nonlinear feature. The air gap flux density, back electromotive force (EMF) and torque are predicted by the model. Based…on the nonlinear model, the thickness of the stator yoke is determined. All of the results obtained by the proposed model match with finite element analysis (FEA) results closely, thus the validity of the proposed MEC model is verified.
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Keywords: Counter-rotation dual-rotor flux permanent magnet synchronous machine (CRDR-AFPMSM), nonlinear magnetic equivalent (MEC), saturable permeance, finite element analysis (FEA)
Abstract: Structural health monitoring plays a crucial role in maintaining the long lifespan of large-scale infrastructure. In this paper, a new type of sensing technique for localized structural damage is proposed. This technology can be adopted to measure cracks by using a transparent capacitive sensor. The capacitive sensor is fabricated using a dielectric elastomer with attached stretchable transparent electrodes. The electrodes are ionic conductors. The materials of the sensor are transparent and inexpensive, which make the sensory sheets a feasible application for large surfaces without impeding optical signals. The performance transparency of the sensor is beneficial to visually detect the expansion…of cracks through other non-destructive testing technologies. An experiment was conducted to determine the robustness of the capacitive sensor. Tests on perspex sheet and over-reinforced concrete beam demonstrated the ability of the sensor to detect strains and cracks over the surface that it covered.
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Keywords: Capacitive sensor, structure health monitoring, ionic skin
Abstract: The anatomic variation of Circle of Willis (CoW) has great impact on its compensatory capacity during stroke and cerebral ischemia. In the present study, a series of lumped parameter models were developed and used to simulate the effect of postural changes on the cerebral blood flow in ICA stenosis patients with different anatomic variants of the CoW. The results showed that the asymmetric distribution of cerebral blood flow caused by stenosis was attenuated in standing position in complete and half-complete CoW. However, in incomplete CoW, the decrease in blood flow in the ipsilateral cerebral arteries caused by unilateral ICA stenosis…was dramatic in both supine and standing positions, a likely result of inadequate collateral circulation within the CoW. In conclusion, the anatomic variation of CoW plays a significant role in maintaining the balance of cerebral blood supply in patients with ICA stenosis, especially during postural change.
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Keywords: Circle of Willis, internal carotid artery stenosis, anatomic variation, lumped parameter model, posture change
Abstract: A compact flywheel energy storage system assisted by axial-flux partially-self-bearing permanent magnet motor has been proposed by the authors. The proposed machine combines axial magnetic bearing and motoring functionality into a single magnetic actuator, which not only spins the rotor-flywheel but also generates a levitation force to overcome the gravity. The mathematical model of the levitation force and stiffness of the active magnetic bearing are developed. The relationships between the stiffness and the key motor parameters are studied. High stiffness can be achieved for the special motor design. The derived force model is validated by finite element analysis. The control…system of the levitation force is designed and experimental setup is built. The test results prove the correctness of the mathematical analysis and feasibility of the designed control system.
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Keywords: Stiffness analysis, active magnetic bearing, levitation force control, flywheel energy storage system, partially-self-bearing motor
Abstract: This paper presents a novel expert system based on electroencephalogram (EEG) and demonstrates the process of knowledge acquisition and inference. As we known, the problem-solving mode of expert brains is: They judge the current situation (learn about the problem), and then generate operational decisions to solve problems. However, the experts have difficulty in explaining what they know and how they gain the knowledge. Their perfect performance may be difficult to replicate. The EEG signal may be one of the most predictive and reliable measurements to acquire the expert knowledge as it reflects directly human brain activity. It is supposed that…EEG is a manifestation of the experts' thinking. By the analysis of EEG, we found the regularity of EEG features of the experts in a well-defined problem domain and used the features to reflect the learning and decision-making information of the expert brains to establish the EEG-based expert system. The knowledge base of the EEG-based expert system stores the features that reflect the learning and decision-making activities of the expert brains respectively. Based on the relationship between the two kinds of the EEG features, inference engine of the EEG-based expert system makes an inference to obtain the features that reflect the decisions of the experts. When we encounter the same problem, the brains make the same judgement (learning). After the EEG data acquisition, through the EEG-based expert system, we can get the expert decisions (operations). If we interpret the decisions into actual operations or control, we can solve the problem with the expert performance or control machines more intelligently. In this paper, game experiments have been designed. We used the solution to the operation problem of a game as the basis to establish the model of the EEG-based expert system. The inputs of the system are the collected EEG signals of the users. The outputs are the operations (decisions) of the experts. The results of the EEG analysis show that the activity appeared in the corresponding brain regions and the probability density function (PDF) of the EEG features is concentrated when the experts performed the task (playing the game). By using the sample entropy (SampEn) and Lempel-Ziv complexity (LZC) algorithm, the EEG features of the experts' learning activities and operating activities were extracted respectively. Then, with applying the probability density functions of the features to output PDF control, the mathematical model of the EEG-based expert system was established. In the EEG-based expert system, inference means controlling the feature vectors which reflect the users' learning information from the current situation to get the feature vectors which reflect the operating information of the experts. Finally, the expert system model has been tested on a simulated example and encouraging results have been obtained. The EEG-based expert system can forecast the operating features of the experts. The output of the EEG-based expert system is in accord with the expert mode and the operating curve represented by the physiological signal features can reflect the actual operating information.
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Keywords: Expert system, EEG, sample entropy, Lempel-Ziv complexity, PDF control
Abstract: BACKGROUND: The imaging photoplethysmography (IPPG) technology has been demonstrated to be an effective method for heart rate (HR) monitoring. However, some interference caused by the ambient illumination variation and facial motion severely influences the accuracy of the HR measurement. Some color spaces and color formats are assumed to reduce the interference, and enhance the accuracy of HR estimation. OBJECTIVE: The aim is to identify the optimal color space and format for IPPG based HR measurement. METHODS: Six color spaces and 3 color formats are compared in this study, based on an IPPG based HR measurement system. 424 pieces of videos…captured by the system are used for the selection of the optimal color channel and color space; while 10 pieces of videos are for the identification of the optimal color format. RESULTS: The results shows that the green channel of RGB space is the optimal color channel, and RGB is the optimal color space, in respect of the mean squared error of HR estimation. BayerBG 8bit is found to be the optimal color format for video recording, which can significantly reduce the HR estimation error. CONCLUSIONS: BayerBG 8bit color format for video recording, and RGB color space for video analysis is suggested for the IPPG based HR measurement system. The suitable configuration of color space and format could enhance the accuracy of HR measurement.
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Keywords: Heart rate, color space, color format, IPPG, independent component analysis
Abstract: As promising non-destructive testing (NDT) method, magnetic flux leakage (MFL) testing has been widely applied for steel structure detection. However, magnetic flux leakage (MFL) signal collected by the sensors is weak, especially for the small diameter wire rope. The methods of using the traditional circular coil sensors, or increasing the number of magnets is ineffective in some situations. This study proposes a new method of highly sensitive long-strip-shape coil sensors with an analogue signal processing circuit used to detect wire rope in the timing belt of wind turbines. It is investigated by theory analysis, circuit simulation, and experiment conduction. The…circuit is used to amplify the weak signal and filter high-frequency noise to obtain a high signal-to-noise ratio (SNR). Experiments show that the resolution of the method can reach 3 broken wires of 0.1 mm wire diameter, and the method can not only obtain a high SNR signal but also have good repeatability. Meanwhile, this method will have great significance in practical applications and provide some solutions for other similar NDT projects.
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Keywords: Non-destructive testing (NDT), magnetic flux leakage (MFL), wire rope, coil sensors, analog signal processing circuit