Browsing by Author "Wang, Chieh-Min"

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A magnetic-piezoelectric smart material-structure utilizing magnetic force interaction to optimize the sensitivity of current sensing
(2016-01-01)
Yeh, Po-Chen
;
Chung, Tien-Kan
;
Lai, Chen-Hung
;
Wang, Chieh-Min
;
機械工程學系
This paper presents a magnetic-piezoelectric smart material-structure using a novel magnetic-force-interaction approach to optimize the sensitivity of conventional piezoelectric current sensing technologies. The smart material-structure comprises a CuBe-alloy cantilever beam, a piezoelectric PZT sheet clamped to the fixed end of the beam, and an NdFeB permanent magnet mounted on the free end of the beam. When the smart material-structure is placed close to an AC conductor, the magnet on the beam of the smart structure experiences an alternating magnetic attractive and repulsive force produced by the conductor. Thus, the beam vibrates and subsequently generates a strain in the PZT sheet. The strain produces a voltage output because of the piezoelectric effect. The magnetic force interaction is specifically enhanced through the optimization approach (i.e., achieved by using SQUID and machining method to reorient the magnetization to different directions to maximize the magnetic force interaction). After optimizing, the beam\'s vibration amplitude is significantly enlarged and, consequently, the voltage output is substantially increased. The experimental results indicated that the smart material-structure optimized by the proposed approach produced a voltage output of 4.01 V-rms with a sensitivity of 501 m V-rms/A when it was placed close to a conductor with a current of 8 A at 60 Hz. The optimized voltage output and sensitivity of the proposed smart structure were approximately 316 % higher than those (1.27 V-rms with 159 m V-rms/A) of representative piezoelectric-based current sensing technologies presented in other studies. These improvements can significantly enable the development of more self-powered wireless current sensing applications in the future.
A magnetic-piezoelectric smart material-structure utilizing magnetic force interaction to optimize the sensitivity of current sensing
(2016-01)
Yeh, Po-Chen
;
Chung, Tien-Kan
;
Lai, Chen-Hung
;
Wang, Chieh-Min
;
機械工程學系
This paper presents a magnetic-piezoelectric smart material-structure using a novel magnetic-force-interaction approach to optimize the sensitivity of conventional piezoelectric current sensing technologies. The smart material-structure comprises a CuBe-alloy cantilever beam, a piezoelectric PZT sheet clamped to the fixed end of the beam, and an NdFeB permanent magnet mounted on the free end of the beam. When the smart material-structure is placed close to an AC conductor, the magnet on the beam of the smart structure experiences an alternating magnetic attractive and repulsive force produced by the conductor. Thus, the beam vibrates and subsequently generates a strain in the PZT sheet. The strain produces a voltage output because of the piezoelectric effect. The magnetic force interaction is specifically enhanced through the optimization approach (i.e., achieved by using SQUID and machining method to reorient the magnetization to different directions to maximize the magnetic force interaction). After optimizing, the beam\'s vibration amplitude is significantly enlarged and, consequently, the voltage output is substantially increased. The experimental results indicated that the smart material-structure optimized by the proposed approach produced a voltage output of 4.01 V-rms with a sensitivity of 501 m V-rms/A when it was placed close to a conductor with a current of 8 A at 60 Hz. The optimized voltage output and sensitivity of the proposed smart structure were approximately 316 % higher than those (1.27 V-rms with 159 m V-rms/A) of representative piezoelectric-based current sensing technologies presented in other studies. These improvements can significantly enable the development of more self-powered wireless current sensing applications in the future.
A MAGNETIC/MECHANICAL APPROACH FOR OPTIMIZING A MINIATURE SELF-POWERED CURRENT SENSOR
(2014-01-01)
Chung, Tien-Kan
;
Yeh, Po-Chen
;
Wang, Chieh-Min
;
機械工程學系
;
Department of Mechanical Engineering
In this paper, we demonstrate a magnetic/mechanical approach for optimizing a miniature self-powered current sensor. The sensor consists of a piezoelectric PZT sheet, Cu Be cantilever beam, NdFeB magnet, and mechanical clamp. When the sensor is placed nearby an AC-current carrying wire from a breaker, the magnet fixed on the beam of the sensor experiences an alternative magnetic attractive and repulsive force produced by an AC magnetic field generated by the wire. Due to the alternative magnetic attractive and repulsive force, the magnet fixed on the beam is oscillated. The oscillating beam deforms the PZT sheet and subsequently produces strain in the PZT sheet. Due to the piezoelectric effect, the strain is converted to a voltage response. Through the optimized approach, the voltage output of the sensor is increased from 1.27 volts to 4.01 volts when the sensor is used to detect an AC current-carrying wire of 8 ampere at 60 Hz.
A Magnetic/Piezoelectric-Based Thermal Energy Harvester
(2013)
Chung, Tien-Kan
;
Shukla, Ujjwal
;
Tseng, Chia-Yuan
;
Chen, Chin-Chung
;
Wang, Chieh-Min
In this paper, we demonstrate a non-contact magnetic/piezoelectric-based thermal energy harvester utilizing an optimized thermal-convection mechanism to enhance the heat transfer in the energy harvesting/converting process in order to increase the power output. The harvester consists of a CuBe spring, Gadolinium soft magnet, NdFeB hard magnets, frame, and piezoelectric PZT cantilever beams. According to the configuration, the energy harvesting/converting process under a temperature-difference is cyclic. Thus, the piezoelectric beams continuously oscillate and subsequently produce voltage responses due to the piezoelectric effect. The maximum voltage response of the harvester under a temperature-difference of 25 degrees C is 16.6 mV with a cycling frequency of 0.58 Hz. In addition, we compare the testing result of the harvester utilizing the new thermal-convection mechanism reported in this paper and using previous thermal-convection mechanism reported elsewhere. According to the comparison, the results show the harvester utilizing the new thermal-convection mechanism has a higher cycling frequency resulting in a higher power output than the previous mechanism.
A MICRO KINETIC ENERGY HARVESTER DEMONSTRATING ENERGY HARVESTING FROM 3-D MECHANICAL MOTION AND POWER INCREASING THROUGH MAGNETIC-BASED FREQUENCY RECTIFICATION
(2012)
Chung, Tien-Kan
;
Wang, Chieh-Min
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Tseng, Chia-Yuan
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Liu, Tzu-Wei
;
Yeh, Po-Chen
In this paper, we report a micro 3-D kinetic energy harvester demonstrating an energy conversion from environmental mechanical-energy (3-D mechanical motion) to electrical energy (voltage output). In addition to energy harvesting/conversion from 3-D motion, we demonstrate a non-contact frequency-up rectification approach which converts an incoming lower vibration frequency to a higher frequency in order to increase the power output of the harvester.
A Miniature Mechanical-Piezoelectric-Configured Three-Axis Vibrational Energy Harvester
(2015-10-01)
Hung, Chiao-Fang
;
Chung, Tien-Kan
;
Yeh, Po-Chen
;
Chen, Chin-Chung
;
Wang, Chieh-Min
In this paper, we demonstrate a novel robust miniature three-axis vibrational energy-harvester using a mechanical-piezoelectric configuration. Using the configuration, the harvester employs Newton\'s law of inertia and the piezoelectric effect to convert either the x-axis or y-axis in-plane and z-axis out-of-plane ambient vibrations into piezoelectric voltage-responses. Under the x-axis vibration (sine-wave, 75 Hz, 3.5 g), our modeled, finite-element analyzed/simulated, and experimental root mean square voltage-response with power-outputs of the harvester (stimulated in resonant with the optimum load) is 525.36 mV with 0.477 mu W, 516.51 mV with 0.461 mu W, and 548 mV with 0.519 mu W, respectively. Under the z-axis vibration (sine-wave, 95 Hz, 3.8 g), the modeled, finite-element analyzed/simulated, and experimental root mean square voltage-response with power-output of the harvester (stimulated in resonant with the optimum load) is 157.35 mV with 0.066 mu W, 170.25 mV with 0.0772 mu W, and 168 mV with 0.075 mu W, respectively. These show that not only both of our modeling and finite-element analysis/simulation can successfully predict the experimental results, but also our harvester is capable of harnessing three-axial ambient vibrations. Moreover, through the piezoelectric lead-zirconate-titanate-connected-in-series approach, the voltage and power outputs are increased. According to these achievements, we believe that our harvester would be an important design reference in industry for future development of microfabrication-based (MEMS-based) three-axial piezoelectric energy harvesters and accelerometers.
A MINIATURE THREE-AXIS PIEZOELECTRIC ENERGY HARVESTER
(2014-01-01)
Hung, Chiao-Fang
;
Wang, Chieh-Min
;
Lin, Shin-Hung
;
Chung, Tien-Kan
;
機械工程學系
In this paper, we demonstrate a novel miniature three-axis piezoelectric energy harvester. The energy harvester consists of four piezoelectric lead zirconate titanate cantilever beams, connector, proof mass, and mechanic frame. Through the connector, a special configuration with a well-constrained mechanism of the energy harvester is achieved. Due to the configuration/mechanism of the energy harvester, the Newton\'s law of inertia and piezoelectric effect are utilized to convert the in-plane (either x-axis or y-axis) and out-of-plane (z-axis) environmental vibrations into voltage responses. This achieves energy harnessing from 3-axial environmental vibration.
A Three-Axial Frequency-Tunable Piezoelectric Energy Harvester Using a Magnetic-Force Configuration
(2014-09-01)
Chung, Tien-Kan
;
Wang, Chieh-Min
;
Yeh, Po-Chen
;
Liu, Tzu-Wei
;
Tseng, Chia-Yuan
To date, researchers have utilized energy harvesters to power wireless sensor nodes as self-powered wireless sensors to create many innovative wireless sensors network applications such as medical monitoring, machining-condition monitoring, and structural-health monitoring. Regarding to energy harvesters, some researchers demonstrated wideband or frequency up-converted vibrational energy harvesters using magnetic force together with piezoelectric materials. However, these harvesters are not able to harness 3-D or three-axial mechanical energy through using one single mechanism or configuration. To address this problem, we report a novel magnetic-force-configured three-axial frequency-tunable piezoelectric energy harvester in this paper. Due to the magnetic-force configuration, the harvester converts ambient three-axial mechanical vibration/motion to piezoelectric voltage-response (i.e., three-axial energy harvesting). Simultaneously, the harvester also converts the ambient vibration/motion at a lower frequency to higher frequency without mechanical wear-out (i.e., noncontact frequency up-conversion). Through modifying the configuration, the oscillating frequency is tunable. By frequency tuning, the harvester\'s oscillating frequency and ambient vibration frequency are able to be matched to maximize the power output. Experimental results show the peak voltage, peak power, and frequency conversion of one single piezoelectric beam of the harvester under an in-plane and out-of-plane vibration is up to 800 mV, 640 nW, and from 7 to 56 Hz, and 27 mV, 729 pW, and from 1 to 294 Hz, respectively. These results confirm the harvester is capable of harnessing energy from 3-D and three-axial mechanical motion/vibration, addressing frequency-mismatching issue, avoiding mechanical wear-out problems, and producing a stable voltage output. Due to these, the energy-harvesting approach will enable more novel and practical wireless sensors network applications in the future.
An Attachable Electromagnetic Energy Harvester Driven Wireless Sensing System Demonstrating Milling-Processes and Cutter-Wear/Breakage-Condition Monitoring
(2016-03-01)
Chung, Tien-Kan
;
Yeh, Po-Chen
;
Lee, Hao
;
Lin, Cheng-Mao
;
Tseng, Chia-Yung
An attachable electromagnetic-energy-harvester driven wireless vibration-sensing system for monitoring milling-processes and cutter-wear/breakage-conditions is demonstrated. The system includes an electromagnetic energy harvester, three single-axis Micro Electro-Mechanical Systems (MEMS) accelerometers, a wireless chip module, and corresponding circuits. The harvester consisting of magnets with a coil uses electromagnetic induction to harness mechanical energy produced by the rotating spindle in milling processes and consequently convert the harnessed energy to electrical output. The electrical output is rectified by the rectification circuit to power the accelerometers and wireless chip module. The harvester, circuits, accelerometer, and wireless chip are integrated as an energy-harvester driven wireless vibration-sensing system. Therefore, this completes a self-powered wireless vibration sensing system. For system testing, a numerical-controlled machining tool with various milling processes is used. According to the test results, the system is fully self-powered and able to successfully sense vibration in the milling processes. Furthermore, by analyzing the vibration signals (i.e., through analyzing the electrical outputs of the accelerometers), criteria are successfully established for the system for real-time accurate simulations of the milling-processes and cutter-conditions (such as cutter-wear conditions and cutter-breaking occurrence). Due to these results, our approach can be applied to most milling and other machining machines in factories to realize more smart machining technologies.
Application Execution Time Prediction for Effective CPU Provisioning in Virtualization Environment
(2017-11-01)
Li, Hong-Wei
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Wu, Yu-Sung
;
Chen, Yi-Yung
;
Wang, Chieh-Min
;
Huang, Yen-Nun
Provisioning of hardware resources through virtual machines (VMs) has been widely used for supporting server consolidation and infrastructure-as-a-cloud computing. We propose NICBLE to support accurate CPU resource provisioning for application workload running on VMs. While CPU is essential for any application workload, not every workload requires the same level of CPU resource. The VM tenants may also have different expectations of application performance and preferences. NICBLE models the execution of an application workload and employs a simulation-based algorithm to predict the impact on application execution time for a hypothetical VM configuration change on the number of CPUs. One may use NICBLE to reason about whether changing the number of CPUs will significantly affect the application performance. We built the NICBLE prototype on top of the Xen hypervisor [1]. NICBLE does not require modification to the guest systems. The performance overhead on the guest system is negligible. Our evaluation indicates that NICBLE is able to provide accurate prediction with an average error rate of less than 15 percent for non-adaptive application workload.
DESIGN, FABRICATION, AND TESTING OF A THERMAL/MECHANICAL/MAGNETIC HYBRID ENERGY MICRO-HARVESTER
(2012)
Chung, Tien-Kan
;
Tseng, Chia-Yuan
;
Chen, Chin-Chung
;
Wang, Chieh-Min
;
機械工程學系
In this paper, we report a novel hybrid energy micro-harvester. The harvester utilizes ferromagnetic materials combined with piezoelectric cantilever beams to harvest the energy from a thermal, mechanical, and magnetic energy sources and subsequently convert the energy to an electrical output. In addition to energy-harvesting, the harvester utilizes a non-contact approach in its structure to avoid the wear problem which frequently occurs in conventional structural-contact approaches.
FUSION: A Unified Application Model for Virtual Mobile Infrastructure
(2017-01-01)
Wang, Chieh-Min
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Wu, Yu-Sung
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Chung, Hsing-Hsuan
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資訊工程學系
;
Department of Computer Science
We proposed a unified application model for virtual mobile infrastructure called FUSION. FUSION bridges the gap between the remote VMI server and the client-side mobile device via supporting bi-directional IPC(inter-process communication) and loosely synchronized file system. FUSION classifies IPC events into two types: IPC events without accessing local resources and IPC events accessing local resource. For IPC events without accessing local resources, FUSION simply hooks the IPC events, forwards them to the remote peer and replays them in the remote environment. For complex IPC events involving with accessing files located in the local device, FUSION will analyze each individual IPC event and transmit the corresponding files to the remote peer with respect to each IPC event. Once the remote application completes its job and the user tries to disconnect with the remote peer, FUSION will synchronize those files back to the local side. The synchronization makes the file changes updated by the remote application visible to the local side. Base on our experimental results, FUSION incurs less than 1% overhead on the system. For simple IPC events without local resource access, FUSION can transmit those IPC events to the remote peer under various network conditions in less than 1200ms. For complex IPC events involving local resource access, FUSION can also serialize and transmit the files efficiently.
Self-Powered Wireless Vibration-Sensing System for Machining Monitoring
(2013)
Chung, Tien-Kan
;
Lee, Hao
;
Tseng, Chia-Yung
;
Lo, Wen-Tuan
;
Wang, Chieh-Min
In this paper, we demonstrate an attachable energy-harvester-powered wireless vibration-sensing module for milling-process monitoring. The system consists of an electromagnetic energy harvester, MEMS accelerometer, and wireless module. The harvester consisting of an inductance and magnets utilizes the electromagnetic-induction approach to harvest the mechanical energy from the milling process and subsequently convert the mechanical energy to an electrical energy. Furthermore, through an energy-storage/rectification circuit, the harvested energy is capable of steadily powering both the accelerometer and wireless module. Through integrating the harvester, accelerometer, and wireless module, a self-powered wireless vibration-sensing system is achieved. The test result of the system monitoring the milling process shows the system successfully senses the vibration produced from the milling and subsequently transmits the vibration signals to the terminal computer. Through analyzing the vibration data received by the terminal computer, we establish a criterion for reconstructing the status, condition, and operating-sequence of the milling process. The reconstructed status precisely matches the real status of the milling process. That is, the system is capable of demonstrating a real-time monitoring of the milling process.
Smartphone Virtualization
(2016)
Chiueh, Tzi-cker
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Lin, Houcheng
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Chao, Ares
;
Anthony
;
Wu, Tan-Gen
Virtualization plays a pivotal role in the success of cloud computing service models and is applied extensively in modern public and private data centers. However, its adoption on end user devices such as laptop/desktop computers and cell phones is relatively scarce, mainly because convincing use cases for client device virtualization have proven elusive so far. As smartphones emerge as the linchpin of everyday computing and communication for regular people and application download becomes a fact of life, the Bring Your Own Cloud (BYOD) problem, in which corporate employees connect their own smartphones to the corporate networks for office work, has put most enterprises in an unenvious position of making a difficult choice between corporate security and employee productivity. One effective solution to the BYOD problem is smartphone virtualization, which provides multiple virtual smartphones on a physical smartphone, and enables a user to use a highly secure but not so flexible virtual smartphone in the work environment and a less secure but more flexible virtual smartphone when outside the work environment. This paper describes the design and implementation of a comprehensive smartphone virtualization system called Brahma, which consists of a virtualized smartphone element and a virtual mobility infrastructure element, and presents the detailed evaluation results of the first Brahma prototype on a commercial smartphone.