With the development of research on integrated photonic quantum information processing,the integration level of the integrated quantum photonic circuits has been increasing continuously,which makes the calibration of ...With the development of research on integrated photonic quantum information processing,the integration level of the integrated quantum photonic circuits has been increasing continuously,which makes the calibration of the phase shifters on the chip increasingly difficult.For the calibration of multiple cascaded phase shifters that is not easy to be decoupled,the resources consumed by conventional brute force methods increase exponentially with the number of phase shifters,making it impossible to calibrate a relatively large number of cascaded phase shifters.In this work,we experimentally validate an efficient method for calibrating cascaded phase shifters that achieves an exponential increase in calibration efficiency compared to the conventional method,thus solving the calibration problem for multiple cascaded phase shifters.Specifically,we experimentally calibrate an integrated quantum photonic circuit with nine cascaded phase shifters and achieve a high-precision calibration with an average fidelity of 99.26%.展开更多
Silicon photonic platforms offer relevance to large markets in many applications,such as optical phased arrays,photonic neural networks,programmable photonic integrated circuits,and quantum computation devices.As one ...Silicon photonic platforms offer relevance to large markets in many applications,such as optical phased arrays,photonic neural networks,programmable photonic integrated circuits,and quantum computation devices.As one of the basic tuning devices,the thermo-optic phase shifter(TOPS)plays an important role in all these applications.A TOPS with the merits of easy fabrication,low power consumption,small thermal time constant,low insertion loss,small footprint,and low crosstalk,is needed to improve the performance and lower the cost of the above applications.To meet these demands,various TOPS have been proposed and experimentally demonstrated on different foundry platforms In this paper,we review the state-of-the-art of TOPS,including metal heater,doped silicon,silicide,with silicon substrate undercut for heat insulation,folded waveguide structure,and multi-pass waveguide structure.We further compare these TOPSs and propose the directions of the future developments on TOPS.展开更多
In this article,a single-layer symmetrical full-port quasi-absorptive filtering phase shifter is presented.The proposed phase shifter is composed of a main quasi-absorptive filtering branch,a reference quasi-absorptiv...In this article,a single-layer symmetrical full-port quasi-absorptive filtering phase shifter is presented.The proposed phase shifter is composed of a main quasi-absorptive filtering branch,a reference quasi-absorptive filtering branch,and two delay lines.The proposed phase shifter achieves both phase controlling function and quasi-absorptive filtering function for the first time.Each quasi-absorptive filtering branch can realize the quasi-absorptive filtering function.Meanwhile,the constant phase shift can be obtained by combining the two quasi-absorptive filtering branches and the two delay lines.The design formulas can be derived from the even-and odd-mode network analysis,and then two quasi-absorptive filtering phase shifters can be devised easily and quickly.For verification,a 90°quasi-absorptive filtering phase shifter,which is critical for circularly polarized antenna systems,is simulated,manufactured,and measured.展开更多
Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output system...Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.展开更多
Sentiment Analysis, an un-abating research area in text mining, requires a computational method for extracting useful information from text. In recent days, social media has become a really rich source to get informat...Sentiment Analysis, an un-abating research area in text mining, requires a computational method for extracting useful information from text. In recent days, social media has become a really rich source to get information about the behavioral state of people(opinion) through reviews and comments. Numerous techniques have been aimed to analyze the sentiment of the text, however, they were unable to come up to the complexity of the sentiments. The complexity requires novel approach for deep analysis of sentiments for more accurate prediction. This research presents a three-step Sentiment Analysis and Prediction(SAP) solution of Text Trend through K-Nearest Neighbor(KNN). At first, sentences are transformed into tokens and stop words are removed. Secondly, polarity of the sentence, paragraph and text is calculated through contributing weighted words, intensity clauses and sentiment shifters. The resulting features extracted in this step played significant role to improve the results. Finally, the trend of the input text has been predicted using KNN classifier based on extracted features. The training and testing of the model has been performed on publically available datasets of twitter and movie reviews. Experiments results illustrated the satisfactory improvement as compared to existing solutions. In addition, GUI(Hello World) based text analysis framework has been designed to perform the text analytics.展开更多
The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireles...The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireless services,including the sub-6 GHz band.In this work,we briefly review several existing designs of millimeter-wave phased arrays for 5G applications,beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one plane.We then move on to array systems that offer two-dimensional(2D)scan capability,which is highly desirable for a majority of 5G applications.Next,in the main body of the paper,we discuss two different strategies for designing scanning arrays,both of which circumvent the use of conventional phase shifters to achieve beam scanning.We note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly;furthermore,alternatives such as active phase shifters,which include radio frequency amplifiers,are both expensive and power-hungry.Given this backdrop,we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave range.The first of these is a Luneburg lens,which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan capability.Next,for second design,we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes,inserted between radiating slots in a waveguide to provide the desired phase shifts for scanning.Finally,we discuss several approaches to enhance the gain of the array by modifying the conventional array configurations.We describe novel techniques for realizing both one-dimensional(1D)and 2D scans by using a reconfigurable metasurface type of panels.展开更多
The feedback collection and analysis has remained an important subject matter for long.The traditional techniques for student feedback analysis are based on questionnaire-based data collection and analysis.However,the...The feedback collection and analysis has remained an important subject matter for long.The traditional techniques for student feedback analysis are based on questionnaire-based data collection and analysis.However,the student expresses their feedback opinions on online social media sites,which need to be analyzed.This study aims at the development of fuzzy-based sentiment analysis system for analyzing student feedback and satisfaction by assigning proper sentiment score to opinion words and polarity shifters present in the input reviews.Our technique computes the sentiment score of student feedback reviews and then applies a fuzzy-logic module to analyze and quantify student’s satisfaction at the fine-grained level.The experimental results reveal that the proposed work has outperformed the baseline studies as well as state-of-the-art machine learning classifiers.展开更多
To implement the multi-way phase shifting maintaining the compact size and simplicity in structure,the uniform reference line concept was proposed for the differential phase shifter.However,the performance in bandwidt...To implement the multi-way phase shifting maintaining the compact size and simplicity in structure,the uniform reference line concept was proposed for the differential phase shifter.However,the performance in bandwidth and phase range deteriorates with the additional requirements considered.To solve this problem,a quarter wavelength coupled line section loaded with open/short stubs is proposed as the basic element to implement the main line and also reference line.According to the theoretical analysis on this basic element,the loading stubs can be used to control the phase shift and also the phase slope of the basic element without affecting the amplitude property.With the predetermined parameters of the uniform reference line,only two parameters are required for the implementation of different differential phase shifts.This demonstrates the high simplicity of the proposed structure.For demonstration,an eight-way differential phase shifter operating at 3.5 GHz was implemented using the vertically installed planar structure.The prototype was further fabricated and measured.Good agreement between simulation and measurement can be observed.The implemented phase shifter can provide a wide range of phase shifting values from 45°to 315°with reference to the uniform reference line over a relative bandwidth of 62.3%.展开更多
A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the l...A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the linear frequency sweep light is generated by propagating an ultra-narrow-linewidth continuous-wave(CW)light through an electro-optic frequency shifter which consists of a dual-parallel Mach-Zehnder modulator(DPMZM)and an electronic 90°hybrid,where the electro-optic frequency shifter is driven by a linear frequency modulated signal generated by a direct digital synthesizer(DDS).Experimental results show that the spatial resolution and signal-to-noise ratio(SNR)of the proposed OFDR scheme without the nonlinear phase compensation are comparable to those of OFDR employing a commercial tunable laser source(TLS),an auxiliary interferometer,and a software-based nonlinear phase compensation method.The proposed OFDR scheme is helpful to reduce the complexity of the optical structure and eliminate the difficulty of developing the nonlinear phase compensation algorithm.展开更多
DSP operation in a Biomedical related therapeutic hardware need to beperformed with high accuracy and with high speed. Portable DSP hardware’s likepulse/heart beat detectors must perform with reduced operational powe...DSP operation in a Biomedical related therapeutic hardware need to beperformed with high accuracy and with high speed. Portable DSP hardware’s likepulse/heart beat detectors must perform with reduced operational power due to lack ofconventional power sources. This work proposes a hybrid biomedical hardware chip inwhich the speed and power utilization factors are greatly improved. Multipliers are thecore operational unit of any DSP SoC. This work proposes a LUT based unsignedmultiplication which is proven to be efficient in terms of high operating speed. For n bitinput multiplication n*n memory array of 2 n bit size is required to memorize all thepossible input and output combination. Various literature works claims to be achieve highspeed multiplication with reduced LUT size by integrating a barrel shifter mechanism.This paper work address this problem, by reworking the multiplier architecture with aparallel operating pre-processing unit which used to change the multiplier and multiplicandorder with respect to the number of computational addition and subtraction stages required.Along with LUT multiplier a low power bus encoding scheme is integrated to limit the powerconstraint of the on chip DSP unit. This paper address both the speed and power optimizationtechniques and tested with various FPGA device families.展开更多
A 60 GHz phased array system for mm wave frequency in 5G is introduced and a 5 bit digitally controlled phase shifter in 40 nm CMOS technology is presented.In a phased array system,the signal to noise ratio(SNR)of the...A 60 GHz phased array system for mm wave frequency in 5G is introduced and a 5 bit digitally controlled phase shifter in 40 nm CMOS technology is presented.In a phased array system,the signal to noise ratio(SNR)of the receiver is improved with the beaming forming function.Therefore,the communication data rate and distance are improved accordingly.The phase shifter is the key component for achieving the beam forming function,and its resolution and power consumption are also very critical.In the second half of this paper,an analysis of phase shifter is introduced,and a 60 GHz 5 bit digitally controlled phase shifter in 40 nm complementary metal oxide semiconductor(CMOS)technology is presented.In this presented phase shifter,a hybrid structure is implemented for its advantage on lower phase deviation while keeping comparable loss.Meanwhile,this digitally controlled phase shifter is much more compact than other works.For all 32 states,the minimum phase error is 1.5°,and the maximum phase error is 6.8°.The measured insertion loss is-20.9±1 dB including pad loss at 60 GHz and the return loss is more than 10 dB over 57-64 GHz.The total chip size is 0.24 mm^2 with 0 mW DC power consumption.展开更多
A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of ...A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of the code. Recently,the chaotic phase shifters were proposed to guarantee the orthogonality by different chaotic signals and spread the spectral content of the quantum states. In this letter, we propose to implement the code division multiple access quantum network by using chaotic phase shifters and synchronization. Due to the orthogonality of the different chaotic phase shifter, every pair of users can faithfully transmit quantum information through a common channel and have little crosstalk between different users. Meanwhile, the broadband spectra of chaotic signals efficiently help the quantum states to defend against channel loss and noise.展开更多
Scintillation light from a liquid noble gas during a neutrino or dark matter experiment lies typically within the vacuum ultraviolet region and might be strongly absorbed by surrounding materials such as light guides ...Scintillation light from a liquid noble gas during a neutrino or dark matter experiment lies typically within the vacuum ultraviolet region and might be strongly absorbed by surrounding materials such as light guides or photomultipliers.Tetraphenyl butadiene(TPB)is a fluorescent material,acts as a wavelength shifter,and can turn UV light into visible light at a peak wavelength of approximately 425 nm,enabling the light signals to be easily detected during physics studies.Compared with a traditional TPB coating method using vapor deposition,we propose an alternative technique applying a spin-coating procedure to facilitate the development of neutrino and dark matter detectors.This article introduces a method to fabricate a TPB film on an acrylic substrate by using a spincoating method,reports the measurements of the sample film thickness and roughness,demonstrates the reemission spectrum,and quantifies the wavelength shifting efficiency.展开更多
In order to improve the efficiency of gear shifter testing,a kind of shift robot with a special pas-sive joint is proposed to complete the human-like shifting operation automatically.The shift robot is mainly composed...In order to improve the efficiency of gear shifter testing,a kind of shift robot with a special pas-sive joint is proposed to complete the human-like shifting operation automatically.The shift robot is mainly composed of two prismatic pairs,a cylindrical pair and a passive joint.The two prismatic pairs act as actuators of the mechanism to complete a part of the shifting operation,and then the shift lever can be pulled into the accurate gear position by the shift torque of the gear shifter.However,the shifting lever may skip the target gear position into the next gear position.In order to solve the gear-skip phenomenon,a limit block is applied to the passive joint.Then,the shifting processes are simulated through the dynamic model of the shift robot.The optimal position of the limit block is de-termined based on its dynamic characteristics.展开更多
Reconfigurable intelligent surface(RIS)is considered as one of the key technologies for the next-generation mobile communication systems.The transmissive RIS is able to achieve dynamic beamforming capability while tra...Reconfigurable intelligent surface(RIS)is considered as one of the key technologies for the next-generation mobile communication systems.The transmissive RIS is able to achieve dynamic beamforming capability while transmitting an in-band RF signal through its aper-ture,and has promising prospects in various practical application scenarios.This paper reviews some of the latest developments of the trans-missive RIS.The approaches for transmissive RIS designs are classified and described briefly.Numerous designs with different phase resolu-tions,such as 1-bit,2-bit or continuous 360°phase shifts,are presented,with detailed discussions on their operating mechanisms and trans-mission performances.The design solutions for various transmissive RIS elements are summarized and compared.展开更多
New circuit implementations of electronically tunable first and second order allpass filter (AP) structures using a Multiplication Mode Current Conveyor (MMCC) building block are presented. The control voltage (V) of ...New circuit implementations of electronically tunable first and second order allpass filter (AP) structures using a Multiplication Mode Current Conveyor (MMCC) building block are presented. The control voltage (V) of the MMCC tunes the desired phase (θ) while the time constant (τ) is adjustable by a Differential Voltage Current Conveyor Transconductance Amplifier (DVCCTA)-based synthetic lossless grounded inductor (L). The circuits are analyzed taking into account the device imperfections which show low active sensitivity features of the designs. The effects of port transfer error (ε) and that of the parasitic capacitances of the active devices had been meticulously examined which indicated that certain deviations in nominal design equations occur;these however, could be minimized with appropriate choice of the circuit passive components. Readily available AD-844 type Current Feedback Amplifier (CFA) elements are utilized for the topology implementation. Satisfactory test results on electronic θ-tunability, upto about 300 KHz, had been verified by PSPICE simulation and with hardware experimentation.展开更多
The circular phased antenna array is commonly used for generating waves bearing Orbital Angular Momentum (OAM) in the radio frequency band, but it achieves a relatively low directivity. To overcome this drawback, we p...The circular phased antenna array is commonly used for generating waves bearing Orbital Angular Momentum (OAM) in the radio frequency band, but it achieves a relatively low directivity. To overcome this drawback, we present here a method to improve the directivity of an OAM circular phased antenna array by embedding it inside a Fabry-Perot cavity. The Fabry-Perot cavity contains three main parts: a partially reflecting surface (PRS), an air cavity and a ground plane. Simulation data show that the directivity of this new OAM antenna achieves an improvement of 8.2 dB over the original array. A prototype is realized and characterized. The simulated and measured characteristics are in good agreement.展开更多
With the increasing demand for high speed reliable communications, smart antennas, such as the Butler Matrix array, can be used to develop a system that increases the performance of a wireless system. The Butler matri...With the increasing demand for high speed reliable communications, smart antennas, such as the Butler Matrix array, can be used to develop a system that increases the performance of a wireless system. The Butler matrix is a switched beam array system which can produce orthogonal uniform beams. The main objective is to improve the efficiency of the power in a 90-degree bend. Also, the double-mitered bend is particularly interesting since it provides a substantially lower reflection coefficient and a lower value of S12 at a frequency of 2.4 GHz compared to an unmitered one. Therefore, this paper describes an optimum design using a double-mitered method with a 2 × 2 and a 4 × 4 Butler Matrix array, operating at 2.4 GHz which is used in wireless systems with an FR4 substrate.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0305200)the Key Research and Development Program of Guangdong Province,China(Grant Nos.2018B030329001 and 2018B030325001)the National Natural Science Foundation of China(Grant No.61974168)。
文摘With the development of research on integrated photonic quantum information processing,the integration level of the integrated quantum photonic circuits has been increasing continuously,which makes the calibration of the phase shifters on the chip increasingly difficult.For the calibration of multiple cascaded phase shifters that is not easy to be decoupled,the resources consumed by conventional brute force methods increase exponentially with the number of phase shifters,making it impossible to calibrate a relatively large number of cascaded phase shifters.In this work,we experimentally validate an efficient method for calibrating cascaded phase shifters that achieves an exponential increase in calibration efficiency compared to the conventional method,thus solving the calibration problem for multiple cascaded phase shifters.Specifically,we experimentally calibrate an integrated quantum photonic circuit with nine cascaded phase shifters and achieve a high-precision calibration with an average fidelity of 99.26%.
基金This work was supported by Chuan-Yu Cooperation Project(No.Cstc2020jscx-cy1hX0006)Chongqing Science and Technology Commission of China(Grant No.cstc2020jscx-msxm0099 and cstc2020jscx-msxm0100)Chongqing Natural Science Foundation of China(No.cstc2020jcyj-msxm3725).
文摘Silicon photonic platforms offer relevance to large markets in many applications,such as optical phased arrays,photonic neural networks,programmable photonic integrated circuits,and quantum computation devices.As one of the basic tuning devices,the thermo-optic phase shifter(TOPS)plays an important role in all these applications.A TOPS with the merits of easy fabrication,low power consumption,small thermal time constant,low insertion loss,small footprint,and low crosstalk,is needed to improve the performance and lower the cost of the above applications.To meet these demands,various TOPS have been proposed and experimentally demonstrated on different foundry platforms In this paper,we review the state-of-the-art of TOPS,including metal heater,doped silicon,silicide,with silicon substrate undercut for heat insulation,folded waveguide structure,and multi-pass waveguide structure.We further compare these TOPSs and propose the directions of the future developments on TOPS.
基金supported by National Natural Science Foundations of China(No.U20A20203,No.61971052,U21A20510)the Fundamental Research Funds for the Central Universities(2021XDA07-1)Key Research and Development Project of Guangdong Province(2020B0101080001)。
文摘In this article,a single-layer symmetrical full-port quasi-absorptive filtering phase shifter is presented.The proposed phase shifter is composed of a main quasi-absorptive filtering branch,a reference quasi-absorptive filtering branch,and two delay lines.The proposed phase shifter achieves both phase controlling function and quasi-absorptive filtering function for the first time.Each quasi-absorptive filtering branch can realize the quasi-absorptive filtering function.Meanwhile,the constant phase shift can be obtained by combining the two quasi-absorptive filtering branches and the two delay lines.The design formulas can be derived from the even-and odd-mode network analysis,and then two quasi-absorptive filtering phase shifters can be devised easily and quickly.For verification,a 90°quasi-absorptive filtering phase shifter,which is critical for circularly polarized antenna systems,is simulated,manufactured,and measured.
基金supported by NSFC (No. 61571055)fund of SKL of MMW (No. K201815)Important National Science & Technology Specific Projects (2017ZX03001028)
文摘Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.
文摘Sentiment Analysis, an un-abating research area in text mining, requires a computational method for extracting useful information from text. In recent days, social media has become a really rich source to get information about the behavioral state of people(opinion) through reviews and comments. Numerous techniques have been aimed to analyze the sentiment of the text, however, they were unable to come up to the complexity of the sentiments. The complexity requires novel approach for deep analysis of sentiments for more accurate prediction. This research presents a three-step Sentiment Analysis and Prediction(SAP) solution of Text Trend through K-Nearest Neighbor(KNN). At first, sentences are transformed into tokens and stop words are removed. Secondly, polarity of the sentence, paragraph and text is calculated through contributing weighted words, intensity clauses and sentiment shifters. The resulting features extracted in this step played significant role to improve the results. Finally, the trend of the input text has been predicted using KNN classifier based on extracted features. The training and testing of the model has been performed on publically available datasets of twitter and movie reviews. Experiments results illustrated the satisfactory improvement as compared to existing solutions. In addition, GUI(Hello World) based text analysis framework has been designed to perform the text analytics.
文摘The fifth generation(5G)network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range,which is impossible to achieve using current wireless services,including the sub-6 GHz band.In this work,we briefly review several existing designs of millimeter-wave phased arrays for 5G applications,beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one plane.We then move on to array systems that offer two-dimensional(2D)scan capability,which is highly desirable for a majority of 5G applications.Next,in the main body of the paper,we discuss two different strategies for designing scanning arrays,both of which circumvent the use of conventional phase shifters to achieve beam scanning.We note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly;furthermore,alternatives such as active phase shifters,which include radio frequency amplifiers,are both expensive and power-hungry.Given this backdrop,we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave range.The first of these is a Luneburg lens,which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan capability.Next,for second design,we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes,inserted between radiating slots in a waveguide to provide the desired phase shifts for scanning.Finally,we discuss several approaches to enhance the gain of the array by modifying the conventional array configurations.We describe novel techniques for realizing both one-dimensional(1D)and 2D scans by using a reconfigurable metasurface type of panels.
文摘The feedback collection and analysis has remained an important subject matter for long.The traditional techniques for student feedback analysis are based on questionnaire-based data collection and analysis.However,the student expresses their feedback opinions on online social media sites,which need to be analyzed.This study aims at the development of fuzzy-based sentiment analysis system for analyzing student feedback and satisfaction by assigning proper sentiment score to opinion words and polarity shifters present in the input reviews.Our technique computes the sentiment score of student feedback reviews and then applies a fuzzy-logic module to analyze and quantify student’s satisfaction at the fine-grained level.The experimental results reveal that the proposed work has outperformed the baseline studies as well as state-of-the-art machine learning classifiers.
基金The work described in this paper was supported by the National Natural Science Foundation of China(No.62071503).
文摘To implement the multi-way phase shifting maintaining the compact size and simplicity in structure,the uniform reference line concept was proposed for the differential phase shifter.However,the performance in bandwidth and phase range deteriorates with the additional requirements considered.To solve this problem,a quarter wavelength coupled line section loaded with open/short stubs is proposed as the basic element to implement the main line and also reference line.According to the theoretical analysis on this basic element,the loading stubs can be used to control the phase shift and also the phase slope of the basic element without affecting the amplitude property.With the predetermined parameters of the uniform reference line,only two parameters are required for the implementation of different differential phase shifts.This demonstrates the high simplicity of the proposed structure.For demonstration,an eight-way differential phase shifter operating at 3.5 GHz was implemented using the vertically installed planar structure.The prototype was further fabricated and measured.Good agreement between simulation and measurement can be observed.The implemented phase shifter can provide a wide range of phase shifting values from 45°to 315°with reference to the uniform reference line over a relative bandwidth of 62.3%.
基金the National Natural Science Foundation of China under Grants No.61927821 and No.61575037.
文摘A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the linear frequency sweep light is generated by propagating an ultra-narrow-linewidth continuous-wave(CW)light through an electro-optic frequency shifter which consists of a dual-parallel Mach-Zehnder modulator(DPMZM)and an electronic 90°hybrid,where the electro-optic frequency shifter is driven by a linear frequency modulated signal generated by a direct digital synthesizer(DDS).Experimental results show that the spatial resolution and signal-to-noise ratio(SNR)of the proposed OFDR scheme without the nonlinear phase compensation are comparable to those of OFDR employing a commercial tunable laser source(TLS),an auxiliary interferometer,and a software-based nonlinear phase compensation method.The proposed OFDR scheme is helpful to reduce the complexity of the optical structure and eliminate the difficulty of developing the nonlinear phase compensation algorithm.
文摘DSP operation in a Biomedical related therapeutic hardware need to beperformed with high accuracy and with high speed. Portable DSP hardware’s likepulse/heart beat detectors must perform with reduced operational power due to lack ofconventional power sources. This work proposes a hybrid biomedical hardware chip inwhich the speed and power utilization factors are greatly improved. Multipliers are thecore operational unit of any DSP SoC. This work proposes a LUT based unsignedmultiplication which is proven to be efficient in terms of high operating speed. For n bitinput multiplication n*n memory array of 2 n bit size is required to memorize all thepossible input and output combination. Various literature works claims to be achieve highspeed multiplication with reduced LUT size by integrating a barrel shifter mechanism.This paper work address this problem, by reworking the multiplier architecture with aparallel operating pre-processing unit which used to change the multiplier and multiplicandorder with respect to the number of computational addition and subtraction stages required.Along with LUT multiplier a low power bus encoding scheme is integrated to limit the powerconstraint of the on chip DSP unit. This paper address both the speed and power optimizationtechniques and tested with various FPGA device families.
基金supported by the National Science Foundation of China (No. 61828401)
文摘A 60 GHz phased array system for mm wave frequency in 5G is introduced and a 5 bit digitally controlled phase shifter in 40 nm CMOS technology is presented.In a phased array system,the signal to noise ratio(SNR)of the receiver is improved with the beaming forming function.Therefore,the communication data rate and distance are improved accordingly.The phase shifter is the key component for achieving the beam forming function,and its resolution and power consumption are also very critical.In the second half of this paper,an analysis of phase shifter is introduced,and a 60 GHz 5 bit digitally controlled phase shifter in 40 nm complementary metal oxide semiconductor(CMOS)technology is presented.In this presented phase shifter,a hybrid structure is implemented for its advantage on lower phase deviation while keeping comparable loss.Meanwhile,this digitally controlled phase shifter is much more compact than other works.For all 32 states,the minimum phase error is 1.5°,and the maximum phase error is 6.8°.The measured insertion loss is-20.9±1 dB including pad loss at 60 GHz and the return loss is more than 10 dB over 57-64 GHz.The total chip size is 0.24 mm^2 with 0 mW DC power consumption.
基金supported by the National Natural Science Foundation of China(Grant Nos.61475099 and 61102053)the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices(Grant No.KF201405)+1 种基金the Open Fund of IPOC(BUPT)(Grant No.IPOC2015B004)the Program of State Key Laboratory of Information Security(Grant No.2016-MS-05)
文摘A quantum access network has been implemented by frequency division multiple access and time division multiple access, while code division multiple access is limited for its difficulty to realize the orthogonality of the code. Recently,the chaotic phase shifters were proposed to guarantee the orthogonality by different chaotic signals and spread the spectral content of the quantum states. In this letter, we propose to implement the code division multiple access quantum network by using chaotic phase shifters and synchronization. Due to the orthogonality of the different chaotic phase shifter, every pair of users can faithfully transmit quantum information through a common channel and have little crosstalk between different users. Meanwhile, the broadband spectra of chaotic signals efficiently help the quantum states to defend against channel loss and noise.
基金supported in part by the Guangdong Basic and Applied Basic Research Foundation(No.2019A1515012216)the National Natural Science Foundation of China(No.11505301)the Innovation Training Program for bachelor students at the School of Physics in SYSU
文摘Scintillation light from a liquid noble gas during a neutrino or dark matter experiment lies typically within the vacuum ultraviolet region and might be strongly absorbed by surrounding materials such as light guides or photomultipliers.Tetraphenyl butadiene(TPB)is a fluorescent material,acts as a wavelength shifter,and can turn UV light into visible light at a peak wavelength of approximately 425 nm,enabling the light signals to be easily detected during physics studies.Compared with a traditional TPB coating method using vapor deposition,we propose an alternative technique applying a spin-coating procedure to facilitate the development of neutrino and dark matter detectors.This article introduces a method to fabricate a TPB film on an acrylic substrate by using a spincoating method,reports the measurements of the sample film thickness and roughness,demonstrates the reemission spectrum,and quantifies the wavelength shifting efficiency.
基金Supported by the National Natural Science Foundation of China(No.51975008)the Beijing Municipal Natural Science Foundation(No.3192002).
文摘In order to improve the efficiency of gear shifter testing,a kind of shift robot with a special pas-sive joint is proposed to complete the human-like shifting operation automatically.The shift robot is mainly composed of two prismatic pairs,a cylindrical pair and a passive joint.The two prismatic pairs act as actuators of the mechanism to complete a part of the shifting operation,and then the shift lever can be pulled into the accurate gear position by the shift torque of the gear shifter.However,the shifting lever may skip the target gear position into the next gear position.In order to solve the gear-skip phenomenon,a limit block is applied to the passive joint.Then,the shifting processes are simulated through the dynamic model of the shift robot.The optimal position of the limit block is de-termined based on its dynamic characteristics.
文摘Reconfigurable intelligent surface(RIS)is considered as one of the key technologies for the next-generation mobile communication systems.The transmissive RIS is able to achieve dynamic beamforming capability while transmitting an in-band RF signal through its aper-ture,and has promising prospects in various practical application scenarios.This paper reviews some of the latest developments of the trans-missive RIS.The approaches for transmissive RIS designs are classified and described briefly.Numerous designs with different phase resolu-tions,such as 1-bit,2-bit or continuous 360°phase shifts,are presented,with detailed discussions on their operating mechanisms and trans-mission performances.The design solutions for various transmissive RIS elements are summarized and compared.
文摘New circuit implementations of electronically tunable first and second order allpass filter (AP) structures using a Multiplication Mode Current Conveyor (MMCC) building block are presented. The control voltage (V) of the MMCC tunes the desired phase (θ) while the time constant (τ) is adjustable by a Differential Voltage Current Conveyor Transconductance Amplifier (DVCCTA)-based synthetic lossless grounded inductor (L). The circuits are analyzed taking into account the device imperfections which show low active sensitivity features of the designs. The effects of port transfer error (ε) and that of the parasitic capacitances of the active devices had been meticulously examined which indicated that certain deviations in nominal design equations occur;these however, could be minimized with appropriate choice of the circuit passive components. Readily available AD-844 type Current Feedback Amplifier (CFA) elements are utilized for the topology implementation. Satisfactory test results on electronic θ-tunability, upto about 300 KHz, had been verified by PSPICE simulation and with hardware experimentation.
文摘The circular phased antenna array is commonly used for generating waves bearing Orbital Angular Momentum (OAM) in the radio frequency band, but it achieves a relatively low directivity. To overcome this drawback, we present here a method to improve the directivity of an OAM circular phased antenna array by embedding it inside a Fabry-Perot cavity. The Fabry-Perot cavity contains three main parts: a partially reflecting surface (PRS), an air cavity and a ground plane. Simulation data show that the directivity of this new OAM antenna achieves an improvement of 8.2 dB over the original array. A prototype is realized and characterized. The simulated and measured characteristics are in good agreement.
文摘With the increasing demand for high speed reliable communications, smart antennas, such as the Butler Matrix array, can be used to develop a system that increases the performance of a wireless system. The Butler matrix is a switched beam array system which can produce orthogonal uniform beams. The main objective is to improve the efficiency of the power in a 90-degree bend. Also, the double-mitered bend is particularly interesting since it provides a substantially lower reflection coefficient and a lower value of S12 at a frequency of 2.4 GHz compared to an unmitered one. Therefore, this paper describes an optimum design using a double-mitered method with a 2 × 2 and a 4 × 4 Butler Matrix array, operating at 2.4 GHz which is used in wireless systems with an FR4 substrate.
