Taiwan Association of Engineering and Technology Innovation: E-Journals
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Optimization of Ducted Propeller Design for the ROV (Remotely Operated Vehicle) using CFD
Get PDFThe development of underwater robot technology is growing rapidly. For reaching the best performance, it is important that the innovation on ROV should be focused on the thruster and propeller.
In this research, the ducted propeller thruster is used while three types of SHUSKHIN nozzle are selected. The design is compared in accordance with the thruster that has been made as the propulsion device of underwater robots. Each type of the thruster model indicates different force and torque. For the analysis, each model is built in Computer Aided Design (Rhinoceros) program packages and Computational Fluid Dynamics (CFD) to find the most optimal model which can produce the highest thrust. Among the entire model, the Kaplan series (Ka5-75) with the type C of nozzle has the highest thrust which is 2.53 N or 25.24% of extra thrust.
For the optimization of thrust, genetic Algorithms (GA) is used. The GA can search for parameters in large multi-dimensional design space. Thus, the principle can be applied for determining the initial propeller that produces optimum thrust of ROV. The GA has successfully shown able to obtain an optimal set parameters for propeller characteristics with the best performance
Experimental Study of Progressive Compression Method of Resin Delivery in Liquid Composite Molding
Get PDFA new technique of resin delivery, which we refer to as the progressive compression method (PCM), has been invented to reduce filling time associated with the vacuum assisted resin transfer molding (VARTM) process. In the method, the bag is divided into several segments. During infusion, all segmented bags are pulled away from the preform by the vacuum. Hence, resin is easily infused into the loose preform. Once enough volume of resin is infused, the vacuum within the segmented bags is released in a step-wise manner. The atmospheric pressure of the heated air is progressively applied on the segmented bag that is inflated to compact the wetted preform and drive the resin through the remaining dry preform. The resin flow is enhanced since the dry preform remains loose during the filling process. The research aims to investigate the effect of seven process parameters on the PCM complete filling process by applying Taguchi’s method. All chosen factors are designed with two levels. Experimental results show that the predicted optimum settings are higher vacuum pressure, more compression segment, later initiation of the next compression segment, higher air temperature, later introduction of the heated air, lower initial height of the cavity and less excess infused resin for reducing the filling time. Compared with typical VARTM without flow enhancement, PCM at the optimum settings reduces the filling time by 72.85%
Performance Improvement of a Feedback Control System Using an Accelerometer-Enhanced Velocity Observer
Get PDFThe paper shows how an accelerometer- enhanced velocity estimator can be used to improve the tracking performance of a feedback control system. In contrast to conventional velocity estimators that use positional information only, the accelerometer-enhanced velocity estimator fuses the position sensor and the accelerometer together to produce an improved velocity estimation. Experimental results are presented to show the effectiveness of the accelerometer-enhanced velocity estimator on improving the tracking performance of a linear motion stage
The Realization of Healthcare Combined with Bluetooth and NFC Technology
Get PDFThe quality of life and function are enhanced with the superior technologies integrated and applied to meet the demands of daily life, achieving lower social costs and ensuring the well-being of the social public. Furthermore, to achieve the goals of enhancing the leisure industry and extending parenting education, so as to facilitate users’ physical and mental health, broaden their horizons toward quality life, enhance their cultural standing, and enable them to appropriately stretch outwards in a safe and secure setting, in this paper, the single-chip microcontroller with integrated control of radio frequency identification was combined with the global GPS system, the USB pedometer, and the Bluetooth wireless sensory technology and applied in tourist rolls and the basic physical and mental health care system in travel. Through the technological integration, the wireless sensor Bluetooth device featuring node transfer function and near field communication (NFC) application sends information of the tourist reaching the designated position and corresponding activity range data to the handheld platform of the main controller (leader) inquiring about the personal health information of the user (tourist), thereby enhancing the security of group activities and even allowing the leader to grasp and offer prompt assistance to the tourist should any accident take place
Reduction of Residual Stresses in Sapphire Cover Glass Induced by Mechanical Polishing and Laser Chamfering Through Etching
Get PDFSapphire is a hard and anti-scratch material commonly used as cover glass of mobile devices such as watches and mobile phones. A mechanical polishing using diamond slurry is usually necessary to create mirror surface. Additional chamfering at the edge is sometimes needed by mechanical grinding. These processes induce residual stresses and the mechanical strength of the sapphire work piece is impaired. In this study wet etching by phosphate acid process is applied to relief the induced stress in a 1” diameter sapphire cover glass. The sapphire is polished before the edge is chamfered by a picosecond laser. Residual stresses are measured by laser curvature method at different stages of machining. The results show that the wet etching process effectively relief the stress and the laser machining does not incur serious residual stress
Energy Efficient Fault Tolerant Sensor Node Failure Detection in WSNs
Get PDFIn WSNs, the large numbers of portable sensor nodes are deployed randomly and can fail due to battery problem, environmental conditions or are unattended. Faulty sensor node detection techniques are mainly affected due to energy consumption of sensor nodes in WSNs. Therefore, the primary goal of this investigation is to design energy efficient fault tolerant sensor node failure detection. A faulty sensor node is detected by measuring the Round Trip Delay (RTD) times of Round Trip Paths (RTPs) in WSNs. Fault tolerance is achieved by assigning unique source node or Cluster Head (CH) for each RTP in WSNs. Energy consumed by individual sensor node is minimized due to optimal involvement of sensor nodes in the detection process. The proposed method is implemented and tested on WSNs with six sensor nodes
Performance Evaluations for IEEE 802.15.4-based IoT Smart Home Solution
Get PDFThe Internet of Things (IoT) is going to be a market-changing force for a variety of real-time applications such as e-healthcare, home automation, environmental monitoring, and industrial automation. Low power wireless communication protocols offering long lifetime and high reliability such as the IEEE 802.15.4 standard have been a key enabling technology for IoT deployments and are deployed for home automation recently. The issues of the IEEE 802.15.4 networks have moved from theory to real world deployments. The work presented herein intends to demonstrate the use of the IEEE 802.15.4 standard in recent IoT commercial products for smart home applications: the Smart Home Starter Kit. The contributions of the paper are twofold. First, the paper presents how the IEEE 802.15.4 standard is employed in Smart Home Starter Kit. In particular, network topology, network operations, and data transfer mode are investigated. Second, network performance metrics such as end-to-end (E2E) delay and frame reception ratio (FRR) are evaluated by experiments. In addition, the paper discusses several directions for future improvements of home automation commercial products
Biosignal –Based Multimodal Biometric System
Get PDFThis study concerns personal identification based on electrocardiogram (ECG) and photoplethysmogram (PPG) signals. We manufactured a bio-signal measurement system that can simultaneously measure ECG and PPG signals, using which three channels of ECG signal and one channel of PPG signal were acquired from the right-hand index finger of a total of 33 subsets for 3 minutes. Lead-I signal of the three-channel ECG signal and the one-channel PPG signal were selected for recognition. For each subject, 160 heartbeats were automatically separated from the acquired bio-signals, and a total of 21 features, comprising 15 ECG features, 4 ECG-related PPG features, and 2 features concerning PPG only, were extracted from each heartbeat. Letting the 21 features form a single data point, heartbeat features of each subset were used as the training data for a support vector machine (SVM) classifier, with the number of data points being adjusted from 10 to 80, and the data points (80 - 150) other than the training data were used as the testing data, in order to investigate the recognition performance indices. As a result, the proposed algorithm showed high recognition performance of 99.28% accuracy, 0.88% FRR, 0.85% FAR, 99.28% sensitivity, and 99.31% specificity, when there are 80 training data points. Moreover, even when there are 10 training data points, the proposed algorithm showed the performance of 92.77% accuracy, 7.23% FRR, 6.29% FAR, 92.77% sensitivity, and 93.21% specificity, which can be evaluated as an extremely high recognition performance considering that there was a total of 4,950 testing data points
Secure Data Exchange in Environmental Health Monitoring System through Wireless Sensor Network
Get PDFRecently, disseminating latest sensory information regarding the status of environmental health in the surroundings of human life is one of very important circumstances which must be known by everyone. These circumstances should be accessible at anytime and anywhere by everyone through any type of end-user devices, both fixed and mobile devices, i.e., Desktop PCs, Laptop PCs, and Smartphones. Wireless Sensor Network (WSN) is one of the networks which deals with data sensors distribution from sensor nodes to the gateway node toward a Data Center Server. However, there is a big possibility for many adversaries to intercept and even manipulate data sensors crossing the network. Hence, a secure data sensor exchange in the system would be strongly desirable. In this research, we propose an environmental health conditions monitoring system through WSN and its implementation with considering secure data sensor exchange within the network and secure data sensor access. This work may contribute to support a part of smart cities and take in part the Internet of Thing (IoT) technology. In our proposed system, we collect some environmental health information such as temperature, humidity, luminosity, noise, carbon monoxide (CO) and carbon dioxide (CO2) from sensor nodes. We keep the confidentiality and integrity of transmitted data sensors propagating through IEEE802.15.4-based communication toward a gateway node. Further, the collected data sensors in the gateway are synchronized to the Data Center Server through a secure TCP/IP connection for permanently storing. At anytime and anywhere, only legitimated users who successfully pass-through an attribute-based authentication system are able to access the data sensors
Obtaining the Knowledge of a Server Performance from Non-Intrusively Measurable Metrics
Get PDFMost network services are provided by server computers. To provide these services with good quality, the server performance must be managed adequately. For the server management, the performance information is commonly obtained from the operating system (OS) and hardware of the managed computer. However, this method has a disadvantage. If the performance is degraded by excessive load or hardware faults, it becomes difficult to collect and transmit information. Thus, it is necessary to obtain the information without interfering with the server’s OS and hardware. This paper investigates a technique that utilizes non-intrusively measureable metrics that are obtained through passive traffic monitoring and electric currents monitored by the sensors attached to the power supply. However, these metrics do not directly represent the performance experienced by users. Hence, it is necessary to discover the complicated function that maps the metrics to the true performance information. To discover this function from the measured samples, a machine learning technique based on a decision tree is examined. The technique is important because it is applicable to the power management of server clusters and the immigration control of virtual servers