I received an M.S. degree in Computer Science and a Ph.D. degree in Electrical Engineering, both from the University of Southern California, Los Angeles, California, USA. I am currently a professor at the Department of Electronic Engineering, National Ilan University (NIU), Taiwan. I am the director of the Embedded Systems and Mobile Computing Laboratory at NIU. Prior to joining NIU, I had served at the Data Communication Institute, Ministry of Transportation and Communications as a senior technician. I have been a visiting scholar to the Next Generation Internet Research Center, Beijing Jiaotong University, Information Science Institute, Academia Sinica, and LNMIIT in Jaipur, India. My research interests are in wireless networks, mobile communications, embedded systems, machine learning, and innovative combination of information and communication technologies.
This paper presents an antenna system operating in the UHF band for RFID applications. The RFID m... more This paper presents an antenna system operating in the UHF band for RFID applications. The RFID module is deployed for LPG delivery and management and is incorporated as part of an embedded system. To reduce the space taken by the antenna, a folded meandered-patch monopole is adopted for the antenna of the handheld reader. On the tag side, in order to meet the low cost requirement, a printed dipole antenna is used with the passive tag. T-matching technique is employed to step up the input impedance so that the printed dipole antenna is conjugately matched with the RFID tag microchip manufactured by Texas Instrument (TI). The reader and tag antennas are designed and simulated using the HFSS software. Parameters including return loss, gain, and radar cross section of the antennas are evaluated. Then the simulated return loss of each antenna is compared with the measured result to verify the proposed design. In addition, radio link budgets that describe the backscatter power link of a passive RF tag are evaluated to estimate the read range of the RFID system.
Microwave and Optical Technology Letters, Mar 11, 2014
This article proposes a printed loop tag antenna placed near a human body for use on student radi... more This article proposes a printed loop tag antenna placed near a human body for use on student radio frequency identification cards. The proposed tag antenna printed on a polyvinylchloride card is a one-wavelength loop fed by a T-matching transformer. An equivalent lumped-circuit for the T-matching transformer is presented to synthesize the T-matching feeding structure. A four-layer stratified elliptical cylinder with physical parameters is utilized as a human model for EM simulations. The simulated bandwidth of the T-matching loop tag antenna is 91 MHz (866-957 MHz, 10%). The T-matching structure allows the loop antenna to have wideband characteristics. Experiments revealed that the reading distance ranges from about 3.3 to 26 m when the tag was placed in different positions on the human chest in the open space environment.
Microwave and Optical Technology Letters, Feb 5, 2018
This article presents a compact size and light weight PQHA for handheld UHF RFID reader applicati... more This article presents a compact size and light weight PQHA for handheld UHF RFID reader applications. Quarter-wavelength inverted-F resonators are employed as the basic radiation elements for the four arms of the QHA. The height of the designed reader antenna is only 27 mm so that it features compact size but still preserves satisfactory electrical performance. The antenna is fed by a fourport quadrature phase feeding system fabricated by only lumped elements. The feeding system printed on a FR4 substrate measures only 60 3 60 3 1.6 mm 3. The measured fractional bandwidth of the proposed PQHA system is about 21% and the 3-dB axial ratio bandwidth ranging from 800 to 1000 MHz covers the whole UHF RFID band. The measured maximum gain is around 3.2 dBic in the North American band and the 3-dB beamwidth is about 1208 at 920 MHz. The measured reading distance along line of sight is approximately 7.2 m using a commercial 4W EIRP reader and a standard tag. The advantages of the antenna are easy implementation, light weight and low cost, making it suitable for handheld UHF RFID reader applications. K E Y W O R D S handheld reader antenna, inverted-F antenna, printed quadrifilar helix antenna (PQHA), quadrature-phase feeder, UHF RFID reader antenna
This paper presents a one-wavelength loop antenna fed by an inductively coupled loop for on-body ... more This paper presents a one-wavelength loop antenna fed by an inductively coupled loop for on-body applications. An equivalent circuit for the inductively coupled loop antenna is proposed to synthesize the antenna system with a microchip. The designed tag is printed on a PVC substrate and placed close to a four-layer stratified elliptical cylinder human model. The card-type tag measures 85.5 × 54 × 0.76 mm 3 and is suitable for use on a student ID card for a broad range of applications. The impedance bandwidth of the inductively coupled loop tag antenna is 60 MHz (880-940 MHz, 6.6%), which covers the operating UHF bands in U.S. and Taiwan. The measured reading distance ranges from 2.7 to 5.7 meters when placed at different positions on the chest of a human body in the open site.
This paper presents a circularly polarized tag on a 3 × 3 AMC structure to obtain longer read ran... more This paper presents a circularly polarized tag on a 3 × 3 AMC structure to obtain longer read range for UHF RFID on-body applications. A modified T-matching transformer is employed to achieve conjugate matching with the Monza 4 microchip. To overcome the influence of lossy human body, a cross-dipole tag antenna is directly implemented on the phase-dependent AMC structure to achieve high gain and isolate the influence of the human body. Then, the tag is pasted on a lossy human model to investigate its performance. The study finds that the AMC can increase the antenna gain by 3.34 dB and help generate circularly polarized (CP) wave. The measured fractional bandwidth of impedance is 3.2% which can cover the UHF RFID bands of North America and Taiwan. The measured read range of the tag pasted on a human body reaches 15.7 meters when the reader has 4W EIRP, and the sensitivity of the microchip is −16.7 dBm.
IEEE Transactions on Parallel and Distributed Systems, 1995
In order to execute a parallel PDE (partial differential equation) solver on a shared-memory mult... more In order to execute a parallel PDE (partial differential equation) solver on a shared-memory multiprocessor, we have to avoid memory conflicts in accessing multidimensional data grids. A new multicoloring technique is proposed for speeding sparse matrix operations. The new technique enables parallel access of grid-structured data elements in the shared memory without causing conflicts. The coloring scheme is formulated as an algebraic mapping which can be easily implemented with low overhead on commercial multiprocessors. The proposed multicoloring scheme has been tested on an Alliant FW80 multiprocessor for solving 2D and 3D problem using the CGNR method. Compared to the results reported by Saad (1989) on an identical Alliant system, our results show a factor of 30 times higher performance in Mflops. Multicoloring transforms sparse matrices into ones with a diagonal diagonal block (DDB) structure, enabling parallel LU decomposition in solving PDE problems. The multicoloring technique can also be extended to solve other scientific problems characterized by sparse matrices.
Wireless Personal Multimedia Communications, Dec 31, 2012
This paper reports a four-element array tag antenna close to a human body for UHF Radio frequency... more This paper reports a four-element array tag antenna close to a human body for UHF Radio frequency identification (RFID) applications. The four-element array is based on PIFA grounded by vias, which can enhance the directive gain. The array antenna is fed by a four-port microstrip-line power divider. The input impedance of the power divider is designed to match with that of a Monza® 4 microchip. The parametric analysis of conjugate matching was performed and prototypes were fabricated to verify the simulated results. Experimental tests show that the maximum reading range achieved by an RFID tag equipped with the array antenna achieves about 3.9 m when the tag was mounted on a human body.
Microwave and Optical Technology Letters, Apr 26, 2013
The agreement between simulation and measured results is very good. PIN diode switches are used t... more The agreement between simulation and measured results is very good. PIN diode switches are used to tune the proposed reconfigurable antenna between the two operating frequency bands corresponding to 3G and 4G mobile communication technologies. The radiation pattern and the gain of the antenna have been also investigated and make it, together with its small size, a very good candidate for mobile 3G and 4G smart phones and tablets handsets.
Journal of Electromagnetic Waves and Applications, Apr 20, 2015
This paper presents a compact printed quadrifilar helix antenna (PQHA) for portable UHF RFID read... more This paper presents a compact printed quadrifilar helix antenna (PQHA) for portable UHF RFID reader applications. The circularly polarized PQHA is fed by a feeding network with quadrature-phase and equal amplitude output signals. The quadrature-phase feeding network is composed of a 180° power splitter and two wideband quadrature hybrid couplers implemented by lumped-element circuits. The miniaturized antenna is a one-wavelength resonance type and can preserve high antenna gain. Moreover, the bandwidths of impedance and axial ratio cover the global UHF RFID band (860–960 MHz). The measured impedance bandwidth is about 34.1% and the axial ratio bandwidth covers 700–1,000 MHz. The measured maximum gain is 5.8 dBic and the 3-dB beamwidth is 168°. The height of the entire system is only 79 mm, the radius is 35 mm, and the FR4 substrate for the feeding network is only 80 × 80 × 1.6 mm3. The proposed antenna is suitable for handheld UHF RFID reader applications.
This paper presents a circularly polarized tag on a 3 × 3 AMC structure to obtain longer read ran... more This paper presents a circularly polarized tag on a 3 × 3 AMC structure to obtain longer read range for UHF RFID on-body applications. A modified T-matching transformer is employed to achieve conjugate matching with the Monza 4 microchip. To overcome the influence of lossy human body, a cross-dipole tag antenna is directly implemented on the phase-dependent AMC structure to achieve high gain and isolate the influence of the human body. Then, the tag is pasted on a lossy human model to investigate its performance. The study finds that the AMC can increase the antenna gain by 3.34 dB and help generate circularly polarized (CP) wave. The measured fractional bandwidth of impedance is 3.2% which can cover the UHF RFID bands of North America and Taiwan. The measured read range of the tag pasted on a human body reaches 15.7 meters when the reader has 4W EIRP, and the sensitivity of the microchip is −16.7 dBm.
Epilepsy is one of the most common neurological disorders, which is characterized by unpredictabl... more Epilepsy is one of the most common neurological disorders, which is characterized by unpredictable brain seizure. About 30% of the patients are not even aware that they have epilepsy and many have to undergo surgeries to relieve the pain. Therefore, developing a robust brain-computer interface for seizure prediction can help epileptic patients significantly. In this paper, we propose a hybrid CNN-SVM model for better epileptic seizure prediction. A convolutional neural network (CNN) consists of a multilayer structure, which can be adapted and modified according to the requirement of different applications. A support vector machine is a discriminative classifier which can be described by a separating optimal hyperplane used for categorizing new samples. The combination of CNN and SVM is found to provide an effective way for epileptic prediction. Furthermore, the resulting model is made autonomous using edge computing services and is shown to be a viable seizure prediction method. The...
Journal of Electromagnetic Waves and Applications, 2015
This paper presents a compact printed quadrifilar helix antenna (PQHA) for portable UHF RFID read... more This paper presents a compact printed quadrifilar helix antenna (PQHA) for portable UHF RFID reader applications. The circularly polarized PQHA is fed by a feeding network with quadrature-phase and equal amplitude output signals. The quadrature-phase feeding network is composed of a 180° power splitter and two wideband quadrature hybrid couplers implemented by lumped-element circuits. The miniaturized antenna is a one-wavelength resonance type and can preserve high antenna gain. Moreover, the bandwidths of impedance and axial ratio cover the global UHF RFID band (860–960 MHz). The measured impedance bandwidth is about 34.1% and the axial ratio bandwidth covers 700–1,000 MHz. The measured maximum gain is 5.8 dBic and the 3-dB beamwidth is 168°. The height of the entire system is only 79 mm, the radius is 35 mm, and the FR4 substrate for the feeding network is only 80 × 80 × 1.6 mm3. The proposed antenna is suitable for handheld UHF RFID reader applications.
This paper presents an antenna system operating in the UHF band for RFID applications. The RFID m... more This paper presents an antenna system operating in the UHF band for RFID applications. The RFID module is deployed for LPG delivery and management and is incorporated as part of an embedded system. To reduce the space taken by the antenna, a folded meandered-patch monopole is adopted for the antenna of the handheld reader. On the tag side, in order to meet the low cost requirement, a printed dipole antenna is used with the passive tag. T-matching technique is employed to step up the input impedance so that the printed dipole antenna is conjugately matched with the RFID tag microchip manufactured by Texas Instrument (TI). The reader and tag antennas are designed and simulated using the HFSS software. Parameters including return loss, gain, and radar cross section of the antennas are evaluated. Then the simulated return loss of each antenna is compared with the measured result to verify the proposed design. In addition, radio link budgets that describe the backscatter power link of a passive RF tag are evaluated to estimate the read range of the RFID system.
Microwave and Optical Technology Letters, Mar 11, 2014
This article proposes a printed loop tag antenna placed near a human body for use on student radi... more This article proposes a printed loop tag antenna placed near a human body for use on student radio frequency identification cards. The proposed tag antenna printed on a polyvinylchloride card is a one-wavelength loop fed by a T-matching transformer. An equivalent lumped-circuit for the T-matching transformer is presented to synthesize the T-matching feeding structure. A four-layer stratified elliptical cylinder with physical parameters is utilized as a human model for EM simulations. The simulated bandwidth of the T-matching loop tag antenna is 91 MHz (866-957 MHz, 10%). The T-matching structure allows the loop antenna to have wideband characteristics. Experiments revealed that the reading distance ranges from about 3.3 to 26 m when the tag was placed in different positions on the human chest in the open space environment.
Microwave and Optical Technology Letters, Feb 5, 2018
This article presents a compact size and light weight PQHA for handheld UHF RFID reader applicati... more This article presents a compact size and light weight PQHA for handheld UHF RFID reader applications. Quarter-wavelength inverted-F resonators are employed as the basic radiation elements for the four arms of the QHA. The height of the designed reader antenna is only 27 mm so that it features compact size but still preserves satisfactory electrical performance. The antenna is fed by a fourport quadrature phase feeding system fabricated by only lumped elements. The feeding system printed on a FR4 substrate measures only 60 3 60 3 1.6 mm 3. The measured fractional bandwidth of the proposed PQHA system is about 21% and the 3-dB axial ratio bandwidth ranging from 800 to 1000 MHz covers the whole UHF RFID band. The measured maximum gain is around 3.2 dBic in the North American band and the 3-dB beamwidth is about 1208 at 920 MHz. The measured reading distance along line of sight is approximately 7.2 m using a commercial 4W EIRP reader and a standard tag. The advantages of the antenna are easy implementation, light weight and low cost, making it suitable for handheld UHF RFID reader applications. K E Y W O R D S handheld reader antenna, inverted-F antenna, printed quadrifilar helix antenna (PQHA), quadrature-phase feeder, UHF RFID reader antenna
This paper presents a one-wavelength loop antenna fed by an inductively coupled loop for on-body ... more This paper presents a one-wavelength loop antenna fed by an inductively coupled loop for on-body applications. An equivalent circuit for the inductively coupled loop antenna is proposed to synthesize the antenna system with a microchip. The designed tag is printed on a PVC substrate and placed close to a four-layer stratified elliptical cylinder human model. The card-type tag measures 85.5 × 54 × 0.76 mm 3 and is suitable for use on a student ID card for a broad range of applications. The impedance bandwidth of the inductively coupled loop tag antenna is 60 MHz (880-940 MHz, 6.6%), which covers the operating UHF bands in U.S. and Taiwan. The measured reading distance ranges from 2.7 to 5.7 meters when placed at different positions on the chest of a human body in the open site.
This paper presents a circularly polarized tag on a 3 × 3 AMC structure to obtain longer read ran... more This paper presents a circularly polarized tag on a 3 × 3 AMC structure to obtain longer read range for UHF RFID on-body applications. A modified T-matching transformer is employed to achieve conjugate matching with the Monza 4 microchip. To overcome the influence of lossy human body, a cross-dipole tag antenna is directly implemented on the phase-dependent AMC structure to achieve high gain and isolate the influence of the human body. Then, the tag is pasted on a lossy human model to investigate its performance. The study finds that the AMC can increase the antenna gain by 3.34 dB and help generate circularly polarized (CP) wave. The measured fractional bandwidth of impedance is 3.2% which can cover the UHF RFID bands of North America and Taiwan. The measured read range of the tag pasted on a human body reaches 15.7 meters when the reader has 4W EIRP, and the sensitivity of the microchip is −16.7 dBm.
IEEE Transactions on Parallel and Distributed Systems, 1995
In order to execute a parallel PDE (partial differential equation) solver on a shared-memory mult... more In order to execute a parallel PDE (partial differential equation) solver on a shared-memory multiprocessor, we have to avoid memory conflicts in accessing multidimensional data grids. A new multicoloring technique is proposed for speeding sparse matrix operations. The new technique enables parallel access of grid-structured data elements in the shared memory without causing conflicts. The coloring scheme is formulated as an algebraic mapping which can be easily implemented with low overhead on commercial multiprocessors. The proposed multicoloring scheme has been tested on an Alliant FW80 multiprocessor for solving 2D and 3D problem using the CGNR method. Compared to the results reported by Saad (1989) on an identical Alliant system, our results show a factor of 30 times higher performance in Mflops. Multicoloring transforms sparse matrices into ones with a diagonal diagonal block (DDB) structure, enabling parallel LU decomposition in solving PDE problems. The multicoloring technique can also be extended to solve other scientific problems characterized by sparse matrices.
Wireless Personal Multimedia Communications, Dec 31, 2012
This paper reports a four-element array tag antenna close to a human body for UHF Radio frequency... more This paper reports a four-element array tag antenna close to a human body for UHF Radio frequency identification (RFID) applications. The four-element array is based on PIFA grounded by vias, which can enhance the directive gain. The array antenna is fed by a four-port microstrip-line power divider. The input impedance of the power divider is designed to match with that of a Monza® 4 microchip. The parametric analysis of conjugate matching was performed and prototypes were fabricated to verify the simulated results. Experimental tests show that the maximum reading range achieved by an RFID tag equipped with the array antenna achieves about 3.9 m when the tag was mounted on a human body.
Microwave and Optical Technology Letters, Apr 26, 2013
The agreement between simulation and measured results is very good. PIN diode switches are used t... more The agreement between simulation and measured results is very good. PIN diode switches are used to tune the proposed reconfigurable antenna between the two operating frequency bands corresponding to 3G and 4G mobile communication technologies. The radiation pattern and the gain of the antenna have been also investigated and make it, together with its small size, a very good candidate for mobile 3G and 4G smart phones and tablets handsets.
Journal of Electromagnetic Waves and Applications, Apr 20, 2015
This paper presents a compact printed quadrifilar helix antenna (PQHA) for portable UHF RFID read... more This paper presents a compact printed quadrifilar helix antenna (PQHA) for portable UHF RFID reader applications. The circularly polarized PQHA is fed by a feeding network with quadrature-phase and equal amplitude output signals. The quadrature-phase feeding network is composed of a 180° power splitter and two wideband quadrature hybrid couplers implemented by lumped-element circuits. The miniaturized antenna is a one-wavelength resonance type and can preserve high antenna gain. Moreover, the bandwidths of impedance and axial ratio cover the global UHF RFID band (860–960 MHz). The measured impedance bandwidth is about 34.1% and the axial ratio bandwidth covers 700–1,000 MHz. The measured maximum gain is 5.8 dBic and the 3-dB beamwidth is 168°. The height of the entire system is only 79 mm, the radius is 35 mm, and the FR4 substrate for the feeding network is only 80 × 80 × 1.6 mm3. The proposed antenna is suitable for handheld UHF RFID reader applications.
This paper presents a circularly polarized tag on a 3 × 3 AMC structure to obtain longer read ran... more This paper presents a circularly polarized tag on a 3 × 3 AMC structure to obtain longer read range for UHF RFID on-body applications. A modified T-matching transformer is employed to achieve conjugate matching with the Monza 4 microchip. To overcome the influence of lossy human body, a cross-dipole tag antenna is directly implemented on the phase-dependent AMC structure to achieve high gain and isolate the influence of the human body. Then, the tag is pasted on a lossy human model to investigate its performance. The study finds that the AMC can increase the antenna gain by 3.34 dB and help generate circularly polarized (CP) wave. The measured fractional bandwidth of impedance is 3.2% which can cover the UHF RFID bands of North America and Taiwan. The measured read range of the tag pasted on a human body reaches 15.7 meters when the reader has 4W EIRP, and the sensitivity of the microchip is −16.7 dBm.
Epilepsy is one of the most common neurological disorders, which is characterized by unpredictabl... more Epilepsy is one of the most common neurological disorders, which is characterized by unpredictable brain seizure. About 30% of the patients are not even aware that they have epilepsy and many have to undergo surgeries to relieve the pain. Therefore, developing a robust brain-computer interface for seizure prediction can help epileptic patients significantly. In this paper, we propose a hybrid CNN-SVM model for better epileptic seizure prediction. A convolutional neural network (CNN) consists of a multilayer structure, which can be adapted and modified according to the requirement of different applications. A support vector machine is a discriminative classifier which can be described by a separating optimal hyperplane used for categorizing new samples. The combination of CNN and SVM is found to provide an effective way for epileptic prediction. Furthermore, the resulting model is made autonomous using edge computing services and is shown to be a viable seizure prediction method. The...
Journal of Electromagnetic Waves and Applications, 2015
This paper presents a compact printed quadrifilar helix antenna (PQHA) for portable UHF RFID read... more This paper presents a compact printed quadrifilar helix antenna (PQHA) for portable UHF RFID reader applications. The circularly polarized PQHA is fed by a feeding network with quadrature-phase and equal amplitude output signals. The quadrature-phase feeding network is composed of a 180° power splitter and two wideband quadrature hybrid couplers implemented by lumped-element circuits. The miniaturized antenna is a one-wavelength resonance type and can preserve high antenna gain. Moreover, the bandwidths of impedance and axial ratio cover the global UHF RFID band (860–960 MHz). The measured impedance bandwidth is about 34.1% and the axial ratio bandwidth covers 700–1,000 MHz. The measured maximum gain is 5.8 dBic and the 3-dB beamwidth is 168°. The height of the entire system is only 79 mm, the radius is 35 mm, and the FR4 substrate for the feeding network is only 80 × 80 × 1.6 mm3. The proposed antenna is suitable for handheld UHF RFID reader applications.
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