Addressing issues such as the disconnect between theory and practice and low student engagement in control system education,this paper uses the course“The Working Process of Open-Loop Control Systems”as a case study...Addressing issues such as the disconnect between theory and practice and low student engagement in control system education,this paper uses the course“The Working Process of Open-Loop Control Systems”as a case study to explore the integration of AI technology with the“project-guided and task-driven”teaching model.By constructing a four-dimensional teaching framework of“situation-task-activity-evaluation,”AI tools are embedded in project practices such as the construction of a mechanical timed flower watering device and the optimization of a digital timed flower watering device,achieving precision,interactivity,and personalization in the teaching process.Teaching practice demonstrates that this model significantly enhances students’technical awareness,materialization capabilities,and engineering thinking,providing a reference for the teaching reform of technical courses in high school education.展开更多
We present a gain adaptive tuning method for fiber Raman amplifier(FRA) using two-stage neural networks(NNs) and double weights updates. After training the connection weights of two-stage NNs separately in training ph...We present a gain adaptive tuning method for fiber Raman amplifier(FRA) using two-stage neural networks(NNs) and double weights updates. After training the connection weights of two-stage NNs separately in training phase, the connection weights of the unified NN are updated again in verification phase according to error between the predicted and target gains to eliminate the inherent error of the NNs. The simulation results show that the mean of root mean square error(RMSE) and maximum error of gains are 0.131 d B and 0.281 d B, respectively. It shows that the method can realize adaptive adjustment function of FRA gain with high accuracy.展开更多
Dear Editor,Obesity is an increasingly prevalent global metabolic disorder,yet effctive long-term interventions remain elusive.Recent studies have highlighted a novel peptide,Urocortin 3(UCN3),which shows potential fo...Dear Editor,Obesity is an increasingly prevalent global metabolic disorder,yet effctive long-term interventions remain elusive.Recent studies have highlighted a novel peptide,Urocortin 3(UCN3),which shows potential for obesity intervention[1].展开更多
Weizhou Island,located in Beihai,Guangxi Province,is recognized as the largest paleovolcanic island in China,characterized by its relatively young geological age.The development of island tourism has progressively est...Weizhou Island,located in Beihai,Guangxi Province,is recognized as the largest paleovolcanic island in China,characterized by its relatively young geological age.The development of island tourism has progressively established it as a significant tourist attraction within Beihai,transforming the area into a prominent leisure and tourism resort.As tourism on Weizhou Island continues to develop both in scope and in depth,it has increasingly influenced the sense of gain among the local community residents.Currently,in alignment with the strategic objective of achieving common prosperity,it is crucial to comprehend and enhance the sense of gain experienced by residents in island tourism destinations,as this is vital for the achievement of this overarching goal.Taking the residents of Weizhou Island in Beihai as the subjects,this paper constructs their sense of gain related to tourism,employing grounded theory.It posits that the residents’sense of gain comprises four primary dimensions:sense of economic gain,sense of social gain,sense of cultural gain,and sense of environmental gain.Additionally,the paper examines the factors that influence these dimensions.Based on this foundation,effective strategies are proposed to enhance the sense of gain among community residents in island tourism destinations,thereby promoting the sustainable development of island tourism.展开更多
Vibration-induced bias deviation,which is generated by intensity fluctuations and additional phase differences,is one of the vital errors for fiber optic gyroscopes(FOGs)operating in vibration environment and has seve...Vibration-induced bias deviation,which is generated by intensity fluctuations and additional phase differences,is one of the vital errors for fiber optic gyroscopes(FOGs)operating in vibration environment and has severely restricted the applications of high-precision FOGs.The conventional methods for suppressing vibration-induced errors mostly concentrate on reinforcing the mechanical structure and optical path as well as the compensation under some specific operation parameters,which have very limited effects for high-precision FOGs maintaining performances under vibration.In this work,a technique of suppressing the vibration-induced bias deviation through removing the part related to the varying gain from the rotation-rate output is put forward.Particularly,the loop gain is extracted out by adding a gain-monitoring wave.By demodulating the loop gain and the rotation rate simultaneously under distinct frequencies and investigating their quantitative relationship,the vibrationinduced bias error is compensated without limiting the operating parameters or environments,like the applied modulation depth.The experimental results show that the proposed method has achieved the reduction of bias error from about 0.149°/h to0.014°/h during the random vibration with frequencies from20 Hz to 2000 Hz.This technique provides a feasible route for enhancing the performances of high-precision FOGs heading towards high environmental adaptability.展开更多
The quality of spectrum sensing plays a significant role in determining the outage probability during the data transmission phase in an interweave cognitive radio network.If the secondary user(SU)fails to detect the p...The quality of spectrum sensing plays a significant role in determining the outage probability during the data transmission phase in an interweave cognitive radio network.If the secondary user(SU)fails to detect the primary user(PU)activity,it can re-sult in interference that limits the system performance.Additionally,since the wireless medium is broadcast in nature,there is a risk of eavesdroppers intercepting the cognitive users’data.Therefore,it is crucial to consider secrecy in the system analysis.In this paper,we analyze the secrecy outage probability(SOP)at the secondary receiver and derive the secret diversity gain for an interweave cognitive multiple-input multiple-output(MIMO)fading channel in the presence of an eavesdropper.Our study takes into account the ef-fects of the fading channel,the PU interference,and the eavesdropper on both spectrum sensing and data transmission phases.We demonstrate that utilizing all the antennas for sensing eliminates the limiting effects of missed detection probability and PU interference on the secret diversity gain.As a result,the cognitive user can achieve the same level of secret diversity gain as a conventional non-cognitive system(CNCS).Our an-alytical results are further validated through simula-tions.展开更多
To address the significant degradation of Space-Time Adaptive Processing(STAP)performance when the array elements have mutual coupling and gain/phase errors,a STAP algorithm with adaptive calibration for the above two...To address the significant degradation of Space-Time Adaptive Processing(STAP)performance when the array elements have mutual coupling and gain/phase errors,a STAP algorithm with adaptive calibration for the above two array errors is proposed in this article.First,based on a defined error matrix that simultaneously considers both array mutual coupling and gain/phase errors,a STAP signal model including these errors is given.Then,utilizing the defined signal model,it is demonstrated that the estimation of the defined error matrix can be formulized as a standard convex optimization problem with the low-rank structure of the clutter covariance matrix and the subspace projection theory.Once the defined error matrix is estimated by solving the convex optimization problem,it is illustrated that a STAP method with adaptive calibration of the mutual coupling and gain/phase errors is coined.Analyses also show that the proposed adaptive calibration algorithm only needs one training sample to construct the adaptive weight vector.Therefore,it can achieve a good detection performance even with severe non-homogeneous clutter environments.Finally,the simulation experiments verify the effectiveness of the proposed algorithm and the correctness of the analytical results.展开更多
This paper proposes a separated trajectory tracking controller for fishing ships at sea state level 6 to solve the trajectory tracking problem of a fishing ship in a 6-level sea state,and to adapt to different working...This paper proposes a separated trajectory tracking controller for fishing ships at sea state level 6 to solve the trajectory tracking problem of a fishing ship in a 6-level sea state,and to adapt to different working environments and safety requirements.The nonlinear feedback method is used to improve the closed-loop gain shaping algorithm.By introducing the sine function,the problem of excessive control energy of the system can be effectively solved.Moreover,an integral separation design is used to solve the influence of the integral term in conventional PID controllers on the transient performance of the system.In this paper,a common 32.98 m large fiberglass reinforced plastic(FRP)trawler is adopted for simulation research at the winds scale of Beaufort No.7.The results show that the track error is smaller than 3.5 m.The method is safe,feasible,concise and effective and has popularization value in the direction of fishing ship trajectory tracking control.This method can be used to improve the level of informatization and intelligence of fishing ships.展开更多
Objectives:This study was conducted to determine the effect of multidisciplinary nursing intervention(MNI)on interdialytic weight gain(IDWG)and quality of life(QoL)among chronic hemodialysis patients.Materials and Met...Objectives:This study was conducted to determine the effect of multidisciplinary nursing intervention(MNI)on interdialytic weight gain(IDWG)and quality of life(QoL)among chronic hemodialysis patients.Materials and Methods:Quantitative research approach with randomized-controlled,single-blind trial was conducted among 120 chronic hemodialysis patients in Institute of Medical Sciences and SUM Hospital Bhubaneswar,Odisha,India from February 2023 to February 2024.Participants were randomly assigned into the experimental group(n1=65)and control group(n2=55)by block randomization methods.The experimental group received the intervention phase up to the 6th week,along with the usual treatment,and the control group received only standard treatment up to the end of the study.After that,they received the diet chart plan and fluid distribution timetable.Results:Significant improvements were found in IDWG and QoL for the experimental group.The experimental group exhibited a sharp decline in weight gain within the group(F=20.05,P<0.001)between the group(F=13.02,P<0.001),interaction effects between the groups across the time point(F=5.67,P<0.005).Kidney disease QoL scores(KDQOL^(TM)36)increased from 49.38±9.56 to 58.63±6.04 in the experimental group,compared to an increase from 50.84±9.25 to 52.04±8.02 in the control group.Conclusion:This trial showed that MNIs significantly reduced IDWG and improved KDQOL^(TM)36 scores,with the experimental group outperforming the control,highlighting the intervention’s effectiveness.展开更多
The Ocean 4A scatterometer, expected to be launched in 2024, is poised to be the world’s first spaceborne microwave scatterometer utilizing a digital beamforming system. To ensure high-precision measurements and perf...The Ocean 4A scatterometer, expected to be launched in 2024, is poised to be the world’s first spaceborne microwave scatterometer utilizing a digital beamforming system. To ensure high-precision measurements and performance sta-bility across diverse environments, stringent requirements are placed on the dynamic range of its receiving system. This paper provides a detailed exposition of a field-programmable gate array (FPGA)-based automatic gain control (AGC) design for the spaceborne scatterometer. Implemented on an FPGA, the algo-rithm harnesses its parallel processing capabilities and high-speed performance to monitor the received echo signals in real time. Employing an adaptive AGC algorithm, the system gene-rates gain control codes applicable to the intermediate fre-quency variable attenuator, enabling rapid and stable adjust-ment of signal amplitudes from the intermediate frequency amplifier to an optimal range. By adopting a purely digital pro-cessing approach, experimental results demonstrate that the AGC algorithm exhibits several advantages, including fast con-vergence, strong flexibility, high precision, and outstanding sta-bility. This innovative design lays a solid foundation for the high-precision measurements of the Ocean 4A scatterometer, with potential implications for the future of spaceborne microwave scatterometers.展开更多
This research presents a compact,high-gain millimeter-wave antenna tailored for reliable 5 G communication in high-speed railway environments.The proposed antenna supports dual-band operation at 28 GHz(n257/n258)and 3...This research presents a compact,high-gain millimeter-wave antenna tailored for reliable 5 G communication in high-speed railway environments.The proposed antenna supports dual-band operation at 28 GHz(n257/n258)and 38 GHz(n260),enabling robust Vehicle-to-Infrastructure(V2I)links required for next-generation railway systems.The radiator occupies only 12 mm×8mm on a Rogers 6010LM substrate(ε_(r)=10.2,h=0.64 mm).A Metallic Ground-Backing(MGB)reflector,positioned 9mm behind the patch—λ/4 at 28 GHz—enhances forward radiation,suppresses back-lobes,and ensures highly directional coverage along railway tracks.The antenna achieves measured peak gains of 7.96 dBi at 28 GHz and 8.20 dBi at 38 GHz,with excellent impedance matching and stable radiation patterns under mobility scenarios.Its unique combination of compact footprint,reflectoraided gain enhancement,and stable dual-band performance under dynamic conditions distinguishes it from conventional millimeter-wave solutions,making it a strong candidate for 5G-based high-speed railway communication modules and arrays.展开更多
A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achie...A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achieve a low noise characteristic, careful optimizations of gate width are performed to reduce gate resistance. Absorption circuits and an elaborate bias structure with a resistor-capacitor network are employed to improve stability. Multiple resonance points and negative feedback technologies are used to widen the bandwidth. Measurements show a noise figure （NF） of less than 2.0dB,and the lowest NF is only 1.6dB at a frequency of 31GHz. In the whole operation band,the LNA has a gain of higher than 26dB,and an input return loss and output return loss of more than 11 and 13dB,respectively. The output power at ldB compression gain of 36GHz is about 14dBm. The chip area is 2.4mm ×1mm.展开更多
The rate equation model is setup for the signal gain, pump absorption and output noise spectrum of bidirectional EDFA (Bi EDFA) including numbers of signals, pumps of arbitrary direction, amplified spontaneous emissi...The rate equation model is setup for the signal gain, pump absorption and output noise spectrum of bidirectional EDFA (Bi EDFA) including numbers of signals, pumps of arbitrary direction, amplified spontaneous emission (ASE) and inherent loss. The influence of erbium doped fiber length, input signal power, pump style and pump power on the gain characteristics of Bi EDFA is analyzed. Forward and backward noise figure for different pump style versus bidirectional input signal power is investigated.展开更多
Using Harrison's model and anisotropic parabolic approximation,the band structure of In1- x- y Gay Alx As compressively strained quantum wells is calculated.To design lasers with1.55μm wavelength,it is necessary...Using Harrison's model and anisotropic parabolic approximation,the band structure of In1- x- y Gay Alx As compressively strained quantum wells is calculated.To design lasers with1.55μm wavelength,it is necessary to an- alyze the well width,differential gain,transparency carrier density and the characteristic gain for an arbitrary com- position.Some useful empirical formulas are also presented.展开更多
A novel wide-range CMOS variable gain amplifier （VGA） topology is presented. The proposed VGA is composed of a variable transconductor and a novel variable output resistor and can offer a high gain variation range o...A novel wide-range CMOS variable gain amplifier （VGA） topology is presented. The proposed VGA is composed of a variable transconductor and a novel variable output resistor and can offer a high gain variation range of 80dB while using a single variable-gain stage. Temperature-compensation and decibel-linear gain characteristic are achieved by using a control circuit that provides a gain error lower than ±1.5dB over the full temperature and gain ranges. Realized in 0.25μm CMOS technology, a prototype of the proposed VGA provides a total gain range of 64.5dB with 55.6dB-linear range,a P-1dB varying from - 17.5 to 11.5dBm,and a 3dB-bandwith varying from 65 to 860MHz while dissipating 16.5mW from a 2.5V supply voltage.展开更多
文摘Addressing issues such as the disconnect between theory and practice and low student engagement in control system education,this paper uses the course“The Working Process of Open-Loop Control Systems”as a case study to explore the integration of AI technology with the“project-guided and task-driven”teaching model.By constructing a four-dimensional teaching framework of“situation-task-activity-evaluation,”AI tools are embedded in project practices such as the construction of a mechanical timed flower watering device and the optimization of a digital timed flower watering device,achieving precision,interactivity,and personalization in the teaching process.Teaching practice demonstrates that this model significantly enhances students’technical awareness,materialization capabilities,and engineering thinking,providing a reference for the teaching reform of technical courses in high school education.
基金supported by the Natural Science Research Project of Colleges and Universities in Anhui Province (No.KJ2021A0479)the Science Research Program of Anhui University of Finance and Economics (No.ACKYC22082)。
文摘We present a gain adaptive tuning method for fiber Raman amplifier(FRA) using two-stage neural networks(NNs) and double weights updates. After training the connection weights of two-stage NNs separately in training phase, the connection weights of the unified NN are updated again in verification phase according to error between the predicted and target gains to eliminate the inherent error of the NNs. The simulation results show that the mean of root mean square error(RMSE) and maximum error of gains are 0.131 d B and 0.281 d B, respectively. It shows that the method can realize adaptive adjustment function of FRA gain with high accuracy.
基金supported by the Major Project of the Science and Technology Innovation 2030 of China(2021ZD0202103)the National Natural Science Foundation of China(82425023,82171492,and 32300846)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2023B1515040009)the Technology and Innovation Commission of Shenzhen(RCJC20200714114556103,ZDSYS20190902093601675 and JCYJ20230807120302004)the Yunnan Technological Innovation Centre of Drug Addiction Medicine(202305AK340001).
文摘Dear Editor,Obesity is an increasingly prevalent global metabolic disorder,yet effctive long-term interventions remain elusive.Recent studies have highlighted a novel peptide,Urocortin 3(UCN3),which shows potential for obesity intervention[1].
基金Sponsored by the Guangxi Philosophy and Social Sciences Research Annual Project(2024GLF036)Thousands of Young and Middle-aged Backbone Teachers Cultivation Program for Universities and Colleges in Guangxi(2021QGRW061).
文摘Weizhou Island,located in Beihai,Guangxi Province,is recognized as the largest paleovolcanic island in China,characterized by its relatively young geological age.The development of island tourism has progressively established it as a significant tourist attraction within Beihai,transforming the area into a prominent leisure and tourism resort.As tourism on Weizhou Island continues to develop both in scope and in depth,it has increasingly influenced the sense of gain among the local community residents.Currently,in alignment with the strategic objective of achieving common prosperity,it is crucial to comprehend and enhance the sense of gain experienced by residents in island tourism destinations,as this is vital for the achievement of this overarching goal.Taking the residents of Weizhou Island in Beihai as the subjects,this paper constructs their sense of gain related to tourism,employing grounded theory.It posits that the residents’sense of gain comprises four primary dimensions:sense of economic gain,sense of social gain,sense of cultural gain,and sense of environmental gain.Additionally,the paper examines the factors that influence these dimensions.Based on this foundation,effective strategies are proposed to enhance the sense of gain among community residents in island tourism destinations,thereby promoting the sustainable development of island tourism.
基金Fundamental Research Funds for the Central Universities(YWF-23-L-1225)National Natural Science Foundation of China(62201025)Chinese Aeronautical Establishment(2022Z037051001)。
文摘Vibration-induced bias deviation,which is generated by intensity fluctuations and additional phase differences,is one of the vital errors for fiber optic gyroscopes(FOGs)operating in vibration environment and has severely restricted the applications of high-precision FOGs.The conventional methods for suppressing vibration-induced errors mostly concentrate on reinforcing the mechanical structure and optical path as well as the compensation under some specific operation parameters,which have very limited effects for high-precision FOGs maintaining performances under vibration.In this work,a technique of suppressing the vibration-induced bias deviation through removing the part related to the varying gain from the rotation-rate output is put forward.Particularly,the loop gain is extracted out by adding a gain-monitoring wave.By demodulating the loop gain and the rotation rate simultaneously under distinct frequencies and investigating their quantitative relationship,the vibrationinduced bias error is compensated without limiting the operating parameters or environments,like the applied modulation depth.The experimental results show that the proposed method has achieved the reduction of bias error from about 0.149°/h to0.014°/h during the random vibration with frequencies from20 Hz to 2000 Hz.This technique provides a feasible route for enhancing the performances of high-precision FOGs heading towards high environmental adaptability.
文摘The quality of spectrum sensing plays a significant role in determining the outage probability during the data transmission phase in an interweave cognitive radio network.If the secondary user(SU)fails to detect the primary user(PU)activity,it can re-sult in interference that limits the system performance.Additionally,since the wireless medium is broadcast in nature,there is a risk of eavesdroppers intercepting the cognitive users’data.Therefore,it is crucial to consider secrecy in the system analysis.In this paper,we analyze the secrecy outage probability(SOP)at the secondary receiver and derive the secret diversity gain for an interweave cognitive multiple-input multiple-output(MIMO)fading channel in the presence of an eavesdropper.Our study takes into account the ef-fects of the fading channel,the PU interference,and the eavesdropper on both spectrum sensing and data transmission phases.We demonstrate that utilizing all the antennas for sensing eliminates the limiting effects of missed detection probability and PU interference on the secret diversity gain.As a result,the cognitive user can achieve the same level of secret diversity gain as a conventional non-cognitive system(CNCS).Our an-alytical results are further validated through simula-tions.
基金co-supported by the National Natural Science Foundation of China(No.12374431)。
文摘To address the significant degradation of Space-Time Adaptive Processing(STAP)performance when the array elements have mutual coupling and gain/phase errors,a STAP algorithm with adaptive calibration for the above two array errors is proposed in this article.First,based on a defined error matrix that simultaneously considers both array mutual coupling and gain/phase errors,a STAP signal model including these errors is given.Then,utilizing the defined signal model,it is demonstrated that the estimation of the defined error matrix can be formulized as a standard convex optimization problem with the low-rank structure of the clutter covariance matrix and the subspace projection theory.Once the defined error matrix is estimated by solving the convex optimization problem,it is illustrated that a STAP method with adaptive calibration of the mutual coupling and gain/phase errors is coined.Analyses also show that the proposed adaptive calibration algorithm only needs one training sample to construct the adaptive weight vector.Therefore,it can achieve a good detection performance even with severe non-homogeneous clutter environments.Finally,the simulation experiments verify the effectiveness of the proposed algorithm and the correctness of the analytical results.
基金supported by Liaoning Provincial Department of Education 2023 Basic Research Projects for Universities and Colleges(Grant No.JYTQN2023131)Liaoning Provincial Science and Technology Program:Cooperative Control and Recognition of Unmanned Vessels for Fishing Vessel Operation Scenarios(Grant No.600024003)Liaoning Provincial Department of Education Scientific Research Funding Project(Grant No.LJKZ0726).
文摘This paper proposes a separated trajectory tracking controller for fishing ships at sea state level 6 to solve the trajectory tracking problem of a fishing ship in a 6-level sea state,and to adapt to different working environments and safety requirements.The nonlinear feedback method is used to improve the closed-loop gain shaping algorithm.By introducing the sine function,the problem of excessive control energy of the system can be effectively solved.Moreover,an integral separation design is used to solve the influence of the integral term in conventional PID controllers on the transient performance of the system.In this paper,a common 32.98 m large fiberglass reinforced plastic(FRP)trawler is adopted for simulation research at the winds scale of Beaufort No.7.The results show that the track error is smaller than 3.5 m.The method is safe,feasible,concise and effective and has popularization value in the direction of fishing ship trajectory tracking control.This method can be used to improve the level of informatization and intelligence of fishing ships.
文摘Objectives:This study was conducted to determine the effect of multidisciplinary nursing intervention(MNI)on interdialytic weight gain(IDWG)and quality of life(QoL)among chronic hemodialysis patients.Materials and Methods:Quantitative research approach with randomized-controlled,single-blind trial was conducted among 120 chronic hemodialysis patients in Institute of Medical Sciences and SUM Hospital Bhubaneswar,Odisha,India from February 2023 to February 2024.Participants were randomly assigned into the experimental group(n1=65)and control group(n2=55)by block randomization methods.The experimental group received the intervention phase up to the 6th week,along with the usual treatment,and the control group received only standard treatment up to the end of the study.After that,they received the diet chart plan and fluid distribution timetable.Results:Significant improvements were found in IDWG and QoL for the experimental group.The experimental group exhibited a sharp decline in weight gain within the group(F=20.05,P<0.001)between the group(F=13.02,P<0.001),interaction effects between the groups across the time point(F=5.67,P<0.005).Kidney disease QoL scores(KDQOL^(TM)36)increased from 49.38±9.56 to 58.63±6.04 in the experimental group,compared to an increase from 50.84±9.25 to 52.04±8.02 in the control group.Conclusion:This trial showed that MNIs significantly reduced IDWG and improved KDQOL^(TM)36 scores,with the experimental group outperforming the control,highlighting the intervention’s effectiveness.
文摘The Ocean 4A scatterometer, expected to be launched in 2024, is poised to be the world’s first spaceborne microwave scatterometer utilizing a digital beamforming system. To ensure high-precision measurements and performance sta-bility across diverse environments, stringent requirements are placed on the dynamic range of its receiving system. This paper provides a detailed exposition of a field-programmable gate array (FPGA)-based automatic gain control (AGC) design for the spaceborne scatterometer. Implemented on an FPGA, the algo-rithm harnesses its parallel processing capabilities and high-speed performance to monitor the received echo signals in real time. Employing an adaptive AGC algorithm, the system gene-rates gain control codes applicable to the intermediate fre-quency variable attenuator, enabling rapid and stable adjust-ment of signal amplitudes from the intermediate frequency amplifier to an optimal range. By adopting a purely digital pro-cessing approach, experimental results demonstrate that the AGC algorithm exhibits several advantages, including fast con-vergence, strong flexibility, high precision, and outstanding sta-bility. This innovative design lays a solid foundation for the high-precision measurements of the Ocean 4A scatterometer, with potential implications for the future of spaceborne microwave scatterometers.
文摘This research presents a compact,high-gain millimeter-wave antenna tailored for reliable 5 G communication in high-speed railway environments.The proposed antenna supports dual-band operation at 28 GHz(n257/n258)and 38 GHz(n260),enabling robust Vehicle-to-Infrastructure(V2I)links required for next-generation railway systems.The radiator occupies only 12 mm×8mm on a Rogers 6010LM substrate(ε_(r)=10.2,h=0.64 mm).A Metallic Ground-Backing(MGB)reflector,positioned 9mm behind the patch—λ/4 at 28 GHz—enhances forward radiation,suppresses back-lobes,and ensures highly directional coverage along railway tracks.The antenna achieves measured peak gains of 7.96 dBi at 28 GHz and 8.20 dBi at 38 GHz,with excellent impedance matching and stable radiation patterns under mobility scenarios.Its unique combination of compact footprint,reflectoraided gain enhancement,and stable dual-band performance under dynamic conditions distinguishes it from conventional millimeter-wave solutions,making it a strong candidate for 5G-based high-speed railway communication modules and arrays.
文摘A four-stage monolithic microwave integrated circuits （MMIC） low noise amplifier （LNA） operating from 23 to 36GHz is reported using commercially available 0.15μm PHEMT technology. The LNA is self-biased. To achieve a low noise characteristic, careful optimizations of gate width are performed to reduce gate resistance. Absorption circuits and an elaborate bias structure with a resistor-capacitor network are employed to improve stability. Multiple resonance points and negative feedback technologies are used to widen the bandwidth. Measurements show a noise figure （NF） of less than 2.0dB,and the lowest NF is only 1.6dB at a frequency of 31GHz. In the whole operation band,the LNA has a gain of higher than 26dB,and an input return loss and output return loss of more than 11 and 13dB,respectively. The output power at ldB compression gain of 36GHz is about 14dBm. The chip area is 2.4mm ×1mm.
文摘The rate equation model is setup for the signal gain, pump absorption and output noise spectrum of bidirectional EDFA (Bi EDFA) including numbers of signals, pumps of arbitrary direction, amplified spontaneous emission (ASE) and inherent loss. The influence of erbium doped fiber length, input signal power, pump style and pump power on the gain characteristics of Bi EDFA is analyzed. Forward and backward noise figure for different pump style versus bidirectional input signal power is investigated.
文摘Using Harrison's model and anisotropic parabolic approximation,the band structure of In1- x- y Gay Alx As compressively strained quantum wells is calculated.To design lasers with1.55μm wavelength,it is necessary to an- alyze the well width,differential gain,transparency carrier density and the characteristic gain for an arbitrary com- position.Some useful empirical formulas are also presented.
文摘A novel wide-range CMOS variable gain amplifier （VGA） topology is presented. The proposed VGA is composed of a variable transconductor and a novel variable output resistor and can offer a high gain variation range of 80dB while using a single variable-gain stage. Temperature-compensation and decibel-linear gain characteristic are achieved by using a control circuit that provides a gain error lower than ±1.5dB over the full temperature and gain ranges. Realized in 0.25μm CMOS technology, a prototype of the proposed VGA provides a total gain range of 64.5dB with 55.6dB-linear range,a P-1dB varying from - 17.5 to 11.5dBm,and a 3dB-bandwith varying from 65 to 860MHz while dissipating 16.5mW from a 2.5V supply voltage.
