Potential-based integral equations are being explored to develop numerical methods that avoid low frequency breakdown issues and are better suited to couple to quantum physics computations. Important classes of quantum electrodynamics problems are typically formulated in the radiation gauge, leading to interest in efficient numerical solutions able to be performed directly in this gauge. This work presents time domain integral equations for penetrable regions that are developed in the radiation gauge. An appropriate marching-on-in-time discretization scheme is developed that fully conforms to the spatial and temporal Sobolev space properties of the integral equations. It is shown that following this approach leads to a discrete system with improved stability properties that produces accurate results down to very low frequencies. The accuracy and stability of this formulation at low frequencies are shown through numerical results.
{"title":"RADIATION GAUGE POTENTIAL-BASED TIME DOMAIN INTEGRAL EQUATIONS FOR PENETRABLE REGIONS","authors":"T. Roth, W. Chew","doi":"10.2528/pier20072801","DOIUrl":"https://doi.org/10.2528/pier20072801","url":null,"abstract":"Potential-based integral equations are being explored to develop numerical methods that avoid low frequency breakdown issues and are better suited to couple to quantum physics computations. Important classes of quantum electrodynamics problems are typically formulated in the radiation gauge, leading to interest in efficient numerical solutions able to be performed directly in this gauge. This work presents time domain integral equations for penetrable regions that are developed in the radiation gauge. An appropriate marching-on-in-time discretization scheme is developed that fully conforms to the spatial and temporal Sobolev space properties of the integral equations. It is shown that following this approach leads to a discrete system with improved stability properties that produces accurate results down to very low frequencies. The accuracy and stability of this formulation at low frequencies are shown through numerical results.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"8 1","pages":"73-86"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85578946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fluorescence confocal laser scanning endomicroscopy is a novel tool combining confocal microscopy and endoscopy for in-vivo subcellular structure imaging with comparable resolution as the traditional microscope. In this paper, we propose a three-channel fluorescence confocal microscopy system based on fiber bundle and two excitation laser lines of 488 nm and 650 nm. Three fluorescent photomultiplier detecting channels of red, green and blue can record multi-color fluorescence signals from single sample site simultaneously. And its ability for in-vivo multi-channel fluorescence detection at subcellular level is verified. Moreover, the system has achieved an effective field of view of 154 μm in diameter with high resolution. With its multi-laser scanning, multi-channel detection, flexible probing, and in-vivo imaging abilities it will become a powerful tool in bio-chemical research and diagnostics, such as the investigation of the transport mechanism of nano-drugs in small animals.
{"title":"MULTI-LASER SCANNING CONFOCAL FLUORESCENT ENDOSCOPY SCHEME FOR SUBCELLULAR IMAGING (INVITED)","authors":"Xiaomin Zheng, Xiang Li, Qiaowen Lin, Jiajie Chen, Yueqing Gu, Yonghong Shao","doi":"10.2528/pier20092201","DOIUrl":"https://doi.org/10.2528/pier20092201","url":null,"abstract":"Fluorescence confocal laser scanning endomicroscopy is a novel tool combining confocal microscopy and endoscopy for in-vivo subcellular structure imaging with comparable resolution as the traditional microscope. In this paper, we propose a three-channel fluorescence confocal microscopy system based on fiber bundle and two excitation laser lines of 488 nm and 650 nm. Three fluorescent photomultiplier detecting channels of red, green and blue can record multi-color fluorescence signals from single sample site simultaneously. And its ability for in-vivo multi-channel fluorescence detection at subcellular level is verified. Moreover, the system has achieved an effective field of view of 154 μm in diameter with high resolution. With its multi-laser scanning, multi-channel detection, flexible probing, and in-vivo imaging abilities it will become a powerful tool in bio-chemical research and diagnostics, such as the investigation of the transport mechanism of nano-drugs in small animals.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"51 1","pages":"17-23"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88291389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years, deep learning (DL) is becoming an increasingly important tool for solving inverse scattering problems (ISPs). This paper reviews methods, promises, and pitfalls of deep learning as applied to ISPs. More specifically, we review several state-of-the-art methods of solving ISPs with DL, and we also offer some insights on how to combine neural networks with the knowledge of the underlying physics as well as traditional non-learning techniques. Despite the successes, DL also has its own challenges and limitations in solving ISPs. These fundamental questions are discussed, and possible suitable future research directions and countermeasures will be suggested.
{"title":"A REVIEW OF DEEP LEARNING APPROACHES FOR INVERSE SCATTERING PROBLEMS (INVITED REVIEW)","authors":"Xudong Chen, Zhun Wei, Maokun Li, P. Rocca","doi":"10.2528/pier20030705","DOIUrl":"https://doi.org/10.2528/pier20030705","url":null,"abstract":"In recent years, deep learning (DL) is becoming an increasingly important tool for solving inverse scattering problems (ISPs). This paper reviews methods, promises, and pitfalls of deep learning as applied to ISPs. More specifically, we review several state-of-the-art methods of solving ISPs with DL, and we also offer some insights on how to combine neural networks with the knowledge of the underlying physics as well as traditional non-learning techniques. Despite the successes, DL also has its own challenges and limitations in solving ISPs. These fundamental questions are discussed, and possible suitable future research directions and countermeasures will be suggested.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"4 1","pages":"67-81"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83686657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years, electrical impedance tomography (EIT) has attracted intensive interests due to its noninvasive, ionizing radiation-free, and low-cost advantages, which is promising for both biomedical imaging and industry nondestructive tests. The purpose of this paper is to review state-ofthe-art methods including both algorithms and hardware implementations in EIT. More specifically, for the advanced reconstruction algorithms in mainstream, we offer some insights on classification and comparison. As for the measurement equipment, the structure, configuration modes, and typical systems are reviewed. Furthermore, we discuss the limitations and challenges in EIT technique, such as low-spatial resolution and nonlinear-inversion problems, where future directions, such as solving EIT problems with deep learning, have also been addressed.
{"title":"A REVIEW OF ALGORITHMS AND HARDWARE IMPLEMENTATIONS IN ELECTRICAL IMPEDANCE TOMOGRAPHY (INVITED)","authors":"Zheng Zong, Yusong Wang, and Zhun Wei","doi":"10.2528/pier20120401","DOIUrl":"https://doi.org/10.2528/pier20120401","url":null,"abstract":"In recent years, electrical impedance tomography (EIT) has attracted intensive interests due to its noninvasive, ionizing radiation-free, and low-cost advantages, which is promising for both biomedical imaging and industry nondestructive tests. The purpose of this paper is to review state-ofthe-art methods including both algorithms and hardware implementations in EIT. More specifically, for the advanced reconstruction algorithms in mainstream, we offer some insights on classification and comparison. As for the measurement equipment, the structure, configuration modes, and typical systems are reviewed. Furthermore, we discuss the limitations and challenges in EIT technique, such as low-spatial resolution and nonlinear-inversion problems, where future directions, such as solving EIT problems with deep learning, have also been addressed.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"16 1","pages":"59-71"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79141930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new design for a cylindrical dielectric resonator antenna (DRA) with a capability of switching between circular, linear horizontal and linear vertical polarizations is introduced. The DRA, operating at the center frequency of 3.25 GHz, is fed by a microstrip line through two dog-bone slots. In this design, only two PIN diodes are employed as switching elements which significantly decreases the complexity of DC biasing circuits compared to existing designs. The PIN diodes are embedded in transformers connected to the feeding microstrip lines. This technique conveniently allows to make compensations for parasitic effects of the PIN diodes junction capacitors on the antenna matching bandwidth. The circular, linear horizontal and linear vertical polarizations have a bandwidth of 22%, 17% and 18%, respectively. The 3-dB axial ratio bandwidth for the circular polarization is 12%. The measured results obtained from prototyped antenna agree well with simulated results of the designed antenna system, which confirms the validity of the design process.
{"title":"POLARIZATION RECONFIGURABLE SLOT-FED CYLINDRICAL DIELECTRIC RESONATOR ANTENNA","authors":"M. Esmaeili, J. Laurin","doi":"10.2528/pier20041203","DOIUrl":"https://doi.org/10.2528/pier20041203","url":null,"abstract":"A new design for a cylindrical dielectric resonator antenna (DRA) with a capability of switching between circular, linear horizontal and linear vertical polarizations is introduced. The DRA, operating at the center frequency of 3.25 GHz, is fed by a microstrip line through two dog-bone slots. In this design, only two PIN diodes are employed as switching elements which significantly decreases the complexity of DC biasing circuits compared to existing designs. The PIN diodes are embedded in transformers connected to the feeding microstrip lines. This technique conveniently allows to make compensations for parasitic effects of the PIN diodes junction capacitors on the antenna matching bandwidth. The circular, linear horizontal and linear vertical polarizations have a bandwidth of 22%, 17% and 18%, respectively. The 3-dB axial ratio bandwidth for the circular polarization is 12%. The measured results obtained from prototyped antenna agree well with simulated results of the designed antenna system, which confirms the validity of the design process.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"17 1","pages":"61-71"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78764591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhang Yiming, Hui Liu, Chenyang Meng, Yuxin Lin, Y. Zhang, E. Forsberg, Sailing He
A periodic millimeter wave leaky-wave antenna (LWA), which has two different types of radiator elements that enable backward to forward radiation, is proposed. The unit-cell of the LWA consists of two quarter-wavelength microstrip lines and two corrugated substrate integrated waveguide (CSIW) cells with S-shaped quarter-wavelength open-circuit stubs. In addition to two parallel edge radiators, a single etched transverse slot with a tilt angle acts as an ancillary radiator, which ensures impedance matching in a large frequency range and achieves the backward to forward scanning. We analyze the proposed design through simulations, characterize a fabricated prototype, and find it to have good radiation properties including broad impedance bandwidth. The measurement results show a high peak gain from 11 to 15.8 dBi with a large scanning angle range from −34◦ to +22◦ in the K-band operating frequency range.
{"title":"A NOVEL MILLIMETER-WAVE BACKWARD TO FORWARD SCANNING PERIODIC LEAKY-WAVE ANTENNA BASED ON TWO DIFFERENT RADIATOR TYPES","authors":"Zhang Yiming, Hui Liu, Chenyang Meng, Yuxin Lin, Y. Zhang, E. Forsberg, Sailing He","doi":"10.2528/pier20072202","DOIUrl":"https://doi.org/10.2528/pier20072202","url":null,"abstract":"A periodic millimeter wave leaky-wave antenna (LWA), which has two different types of radiator elements that enable backward to forward radiation, is proposed. The unit-cell of the LWA consists of two quarter-wavelength microstrip lines and two corrugated substrate integrated waveguide (CSIW) cells with S-shaped quarter-wavelength open-circuit stubs. In addition to two parallel edge radiators, a single etched transverse slot with a tilt angle acts as an ancillary radiator, which ensures impedance matching in a large frequency range and achieves the backward to forward scanning. We analyze the proposed design through simulations, characterize a fabricated prototype, and find it to have good radiation properties including broad impedance bandwidth. The measurement results show a high peak gain from 11 to 15.8 dBi with a large scanning angle range from −34◦ to +22◦ in the K-band operating frequency range.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"33 1","pages":"31-38"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90697724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Arya, S. Kim, Sungik Park, Donghoon Kim, Rehab S. Hassan, Kyeongjun Ko, Sanghoek Kim
This paper presents a design study of a shark-fin antenna for future railway communications. Three specific bands are considered here as LTE-R (700 MHz), LTE (2100 MHz), and Lower 5G band (3500 MHz). A 3-D metallic structure using the 3D printing technique has been designed and fabricated for the consideration of the required bands. The volume size of the antenna element is 163 × 61.9 × 10 mm3. The multi-physical simulations in terms of the smooth air flow and lower drag coefficient are performed for analyzing the need of shark-fin radome cover. More than 70 MHz bandwidth was observed for the LTE-R band and also a wide band response from 1.4 GHz to 4.2 GHz was observed that cover the required bands well, i.e., the LTE, and Lower 5G band. The proposed shark-fin antenna results in the expected omnidirectional radiation pattern in the horizontal plane, with the radiation efficiency of 71.7%, 92.6%, and 96.4% in the railway environment for the LTE-R, LTE, and Lower 5G band frequency, respectively.
{"title":"SHARK-FIN ANTENNA FOR RAILWAY COMMUNICATIONS IN LTE-R, LTE, AND LOWER 5G FREQUENCY BANDS","authors":"A. Arya, S. Kim, Sungik Park, Donghoon Kim, Rehab S. Hassan, Kyeongjun Ko, Sanghoek Kim","doi":"10.2528/pier20040201","DOIUrl":"https://doi.org/10.2528/pier20040201","url":null,"abstract":"This paper presents a design study of a shark-fin antenna for future railway communications. Three specific bands are considered here as LTE-R (700 MHz), LTE (2100 MHz), and Lower 5G band (3500 MHz). A 3-D metallic structure using the 3D printing technique has been designed and fabricated for the consideration of the required bands. The volume size of the antenna element is 163 × 61.9 × 10 mm3. The multi-physical simulations in terms of the smooth air flow and lower drag coefficient are performed for analyzing the need of shark-fin radome cover. More than 70 MHz bandwidth was observed for the LTE-R band and also a wide band response from 1.4 GHz to 4.2 GHz was observed that cover the required bands well, i.e., the LTE, and Lower 5G band. The proposed shark-fin antenna results in the expected omnidirectional radiation pattern in the horizontal plane, with the radiation efficiency of 71.7%, 92.6%, and 96.4% in the railway environment for the LTE-R, LTE, and Lower 5G band frequency, respectively.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"11 1","pages":"83-94"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82064648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new compressive sensing-based direction of arrival (DOA) estimation technique for source signal detection in the presence of unknown noise, based on the generalized correlation decomposition (GCD) algorithm, is presented. The proposed algorithm does not depend on the singular value decomposition nor on the orthogonality of the signal and the noise subspaces. Hence, the DOA estimation can be done without an a priori knowledge of the number of sources. The proposed algorithm can estimate more sources than the number of physical sensors used without any constraints or assumptions about the nature of the signal sources. It can estimate coherent source signals as well as closely-spaced sources using a small number of snapshots.
{"title":"COMPRESSED SENSING DOA ESTIMATION IN THE PRESENCE OF UNKNOWN NOISE","authors":"A. A. Salama, M. Ahmad, M. Swamy","doi":"10.2528/pierc20031204","DOIUrl":"https://doi.org/10.2528/pierc20031204","url":null,"abstract":"A new compressive sensing-based direction of arrival (DOA) estimation technique for source signal detection in the presence of unknown noise, based on the generalized correlation decomposition (GCD) algorithm, is presented. The proposed algorithm does not depend on the singular value decomposition nor on the orthogonality of the signal and the noise subspaces. Hence, the DOA estimation can be done without an a priori knowledge of the number of sources. The proposed algorithm can estimate more sources than the number of physical sensors used without any constraints or assumptions about the nature of the signal sources. It can estimate coherent source signals as well as closely-spaced sources using a small number of snapshots.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"112 1","pages":"47-62"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79355835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The zeroing of second order correlation functions between output fields after interferences in a 50/50 beam splitter has been accepted decades-long in the quantum optics community as an indicator of the quantum nature of lights. But, a recent work [1] presented some notable discussions and experiments that classical electromagnetic fields can still exhibit the zero correlation under specific conditions. Here, we examine analytically classical and quantum electromagnetic field interferences in a 50/50 beam splitter in the context of the second order correlation function for various input conditions. Adopting the Heisenberg picture in quantum electromagnetics, we examine components of four-term interference terms in the numerator of second order correlation functions and elucidate their physical significance. As such, we reveal the fundamental difference between the classical and quantum interference as illustrated by the Hong-Ou-Mandel (HOM) effect. The quantum HOM effect is strongly associated with: (1) the commutator relation that does not have a classical analogue; (2) the property of Fock states needed to stipulate the one-photon quantum state of the system; and (3) a destructive wave interference effect. Here, (1) and (2) imply the indivisibility of a photon. On the contrary, the classical HOM effect requires the presence of two destructive wave interferences without the need to stipulate a quantum state.
{"title":"CLASSICAL AND QUANTUM ELECTROMAGNETIC INTERFERENCES: WHAT IS THE DIFFERENCE?","authors":"D. Na, W. Chew","doi":"10.2528/pier20060301","DOIUrl":"https://doi.org/10.2528/pier20060301","url":null,"abstract":"The zeroing of second order correlation functions between output fields after interferences in a 50/50 beam splitter has been accepted decades-long in the quantum optics community as an indicator of the quantum nature of lights. But, a recent work [1] presented some notable discussions and experiments that classical electromagnetic fields can still exhibit the zero correlation under specific conditions. Here, we examine analytically classical and quantum electromagnetic field interferences in a 50/50 beam splitter in the context of the second order correlation function for various input conditions. Adopting the Heisenberg picture in quantum electromagnetics, we examine components of four-term interference terms in the numerator of second order correlation functions and elucidate their physical significance. As such, we reveal the fundamental difference between the classical and quantum interference as illustrated by the Hong-Ou-Mandel (HOM) effect. The quantum HOM effect is strongly associated with: (1) the commutator relation that does not have a classical analogue; (2) the property of Fock states needed to stipulate the one-photon quantum state of the system; and (3) a destructive wave interference effect. Here, (1) and (2) imply the indivisibility of a photon. On the contrary, the classical HOM effect requires the presence of two destructive wave interferences without the need to stipulate a quantum state.","PeriodicalId":54551,"journal":{"name":"Progress in Electromagnetics Research-Pier","volume":"55 29 1","pages":"1-13"},"PeriodicalIF":6.7,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75481307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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