Uneven frost heave deformation can shorten the operational lifespan of foundation engineering.Clarifying the mechanisms of uneven frost heave facilitates the targeted mitigation of frost damage.This study focused on a...Uneven frost heave deformation can shorten the operational lifespan of foundation engineering.Clarifying the mechanisms of uneven frost heave facilitates the targeted mitigation of frost damage.This study focused on a water conveyance channel in Jilin Province,northern China,and found after monitoring that the frost heave at the channel bottom lining exceeded that at the crest by 44.5 mm,with the freezing temperature at the bottom being over 2℃lower than that at the crest.Soil columns with an initial gravimetric moisture content of 12%,16%,18%,and 20%were then prepared.The effects of temperature and moisture content on frost heave were analyzed under two freezing conditions(-5℃and-10℃)through unidirectional freezing tests.A coupled thermo-hydro-mechanical(THM)frost heave model,validated by the test results,was further established.In the soil with an initial moisture content of 20%,the formation of ice lenses associated with substantial water migration contributed to a large temperature gradient,which can jointly induce frost heave.Under the-10℃condition,the temperature gradient in the soil column with a 20%initial moisture content reached 0.84℃/cm,the total water migration reached 10.72%,and the frost heave deformation was 1.86 mm.The THM coupling results indicated that,under the interaction of a large temperature gradient and moisture accumulation,the volumetric ice content remained high in the bottom soil during freezing and peaked at 0.36.The frost damage to the bottom soil was severe,and the maximum deformation reached 57 mm.展开更多
This paper deals with the design of bidirectional coupler for broadband power line communication and the impedance matching technique with the power line. This coupler can be used for both transmitting and receiving t...This paper deals with the design of bidirectional coupler for broadband power line communication and the impedance matching technique with the power line. This coupler can be used for both transmitting and receiving the data, acting as transceiver. The impedance mismatching problem is also solved here using line trap circuit. The coupler circuit is capable of transmitting or receiving modulated signals with carrier frequency of 15 MHz which can be used for domestic as well as distribution power networks. Laboratory prototype tested using power line network consists of electrical household appliances and results show that the circuit is able to facilitate bidirectional band pass transmission.展开更多
The global rise in energy demand, particularly in remote and sparsely populated regions, necessitates innovative and cost-effective electrical distribution solutions. Traditional Rural Electrification (RE) methods, li...The global rise in energy demand, particularly in remote and sparsely populated regions, necessitates innovative and cost-effective electrical distribution solutions. Traditional Rural Electrification (RE) methods, like Conventional Rural Electrification (CRE), have proven economically unfeasible in such areas due to high infrastructure costs and low electricity demand. Consequently, Unconventional Rural Electrification (URE) technologies, such as Capacitor Coupled Substations (CCS), are gaining attention as viable alternatives. This study presents the design and simulation of an 80 kW CCS system, which taps power directly from a 132 kV transmission line to supply low-voltage consumers. The critical components of the CCS, the capacitors are calculated, then a MATLAB/Simulink model with the attained results is executed. Mathematical representation and state-space representation for maintaining the desired tapped voltage area also developed. The research further explores the feasibility and operational performance of this CCS configuration, aiming to address the challenges of rural electrification by offering a sustainable and scalable solution. The results show that the desired value of the tapped voltage can be achieved at any level of High Voltage (HV) with the selection of capacitors that are correctly rated. With an adequately designed control strategy, the research also shows that tapped voltage can be attained under both steady-state and dynamic loads. By leveraging CCS technology, the study demonstrates the potential for delivering reliable electricity to underserved areas, highlighting the system’s practicality and effectiveness in overcoming the limitations of conventional distribution methods.展开更多
This paper discusses the numerical modeling of the dynamic coupled analysis of the floating platform and mooring/risers using the asynchronous coupling algorithm with the purpose to improve the computational efficienc...This paper discusses the numerical modeling of the dynamic coupled analysis of the floating platform and mooring/risers using the asynchronous coupling algorithm with the purpose to improve the computational efficiency when multiple lines are connected to the platform. The numerical model of the platform motion simulation in wave is presented. Additionally, how the asynchronous coupling algorithm is implemented during the dynamic coupling analysis is introduced. Through a comparison of the numerical results of our developed model with commercial software for a SPAR platform, the developed numerical model is checked and validated.展开更多
This paper reports a novel dual-band coupled-line bandpass filter.Comprising a quadruple-mode coupled-line resonator,this proposed filter could filter signals on two frequency bands.After introducing two varactors,one...This paper reports a novel dual-band coupled-line bandpass filter.Comprising a quadruple-mode coupled-line resonator,this proposed filter could filter signals on two frequency bands.After introducing two varactors,one of the four resonances could be continuously altered by changing the capacitance of the varactors,thus the two frequency bandwidths could be independently tunned.In this paper,the detailed explanation for its operation is given,and the agreement between the expected and practical performance sufficiently confirms the robustness and effectiveness of this proposed filter.展开更多
An atmosphere-ocean coupled mesoscale modeling system is developed and used to investigate the interactions between a squall line and the upper ocean observed over the western Paci?c warm pool during the Tropical Oc...An atmosphere-ocean coupled mesoscale modeling system is developed and used to investigate the interactions between a squall line and the upper ocean observed over the western Paci?c warm pool during the Tropical Ocean/Global Atmosphere Coupled Ocean and Atmosphere Response Experiment (TOGA-COARE). The modeling system is developed by coupling the Advanced Regional Prediction Sys- tem (ARPS) to the Princeton Ocean Model (POM) through precipitation and two-way exchanges of mo- mentum, heat, and moisture across the air-sea interface. The results indicate that the interaction between the squall-line and the upper ocean produced noticeable di?erences in the sensible and latent heat ?uxes, as compared to the uncoupled cases. Precipitation, which is often ignored in air-sea heat ?ux estimates, played a major role in the coupling between the mesoscale convective system and the ocean. Precipitation a?ected the air-sea interaction through both freshwater ?ux and sensible heat ?ux. The former led to the formation of a thin stable ocean layer underneath and behind the precipitating atmospheric convection. The presence of this stable layer resulted in a more signi?cant convection-induced sea surface temperature (SST) change in and behind the precipitation zone. However, convection-induced SST changes do not seem to play an important role in the intsensi?cation of the existing convective system that resulted in the SST change, as the convection quickly moved away from the region of original SST response.展开更多
A novel millimeter-wave waveguide-to-microstrip transition based on magnetic-coupling is presented in this paper.The mode conversion of electromagnetic field is realized with the ring strip line of arbitrary shape in ...A novel millimeter-wave waveguide-to-microstrip transition based on magnetic-coupling is presented in this paper.The mode conversion of electromagnetic field is realized with the ring strip line of arbitrary shape in the E-plane of rectangular waveguide and the eccentric quasi-coaxial line,which is partially filled with media and consists of outer and inner rectangular conductors.The structure has the advantages of low loss,wide bandwidth,compact structure,and avoiding debug.From 27 GHz to 40 GHz,the experiment results show that the insertion loss is less than 1.2 dB and the return loss is better than 13.5 dB for the back-to-back transition with semicircle ring strip lines.展开更多
A planar circuit structure, which is based on three cascaded pairs of coupled lines, an open stub, and an isolation resistor, is proposed in this paper to design a compact dual.band balun with high isolation. This cir...A planar circuit structure, which is based on three cascaded pairs of coupled lines, an open stub, and an isolation resistor, is proposed in this paper to design a compact dual.band balun with high isolation. This circuit features equal power division with out of phase, all ports matching, high isolation between two outputs, compact structure, and inherent impedance transformation. The closedform design equations are derived based on the traditional transmission.line theory and even.(odd.) mode analysis. A practical dual.band balun, which operates at 0.9/1.8GHz, is designed and fabricated to validate the function of equal power division with out of phase and high isolation between two outputs. The consistency between the simulated and measured results verify the design theory.展开更多
For the first lime, the pressure and flow pulse wave propagation phenomenon is studied in this paper on the basis of he cardiovascular dynamic coupling. E(t)-R model is adopted for left ventricle and T-Y tube model fo...For the first lime, the pressure and flow pulse wave propagation phenomenon is studied in this paper on the basis of he cardiovascular dynamic coupling. E(t)-R model is adopted for left ventricle and T-Y tube model for systemic arteries. Furthermore, impulse response method and Fourier analysis method are employed After reasonable cardiovascular parameters and their value have been selected, the pressure and flow waveforms ape obtained at any poing along the systemic arteries. The results fit measured data well. In addition, the influences of cardiovascular parameters on pulse wave propagation are studied. The work is useful in practice.展开更多
This paper presents a dual band Band Pass Filter (BPF) operating at both the downlink and uplink frequency bands for Ku-band satellite applications. The commonly used frequency band in mobile communications satellites...This paper presents a dual band Band Pass Filter (BPF) operating at both the downlink and uplink frequency bands for Ku-band satellite applications. The commonly used frequency band in mobile communications satellites is the Ku-band. These mobile satellite systems help connect remote regions, vehicles, ships, people and aircraft to other parts of the world and/or other mobile or stationary communications units, in addition to serving as navigation systems. The structure of the proposed filter is based on parallel coupled microstrip lines and four sections are used. Tuning the two operational bands can be achieved using two open-circuited stubs at the first and last sections of the parallel coupled microstrip lines. The proposed filter is adjusted to operate at 12.54 GHz and 14.14 GHz for downlink and uplink bands, respectively. The proposed dual band BPF is fabricated, measured, and good agreement is obtained between simulated and measured results.展开更多
A static security assessment approach considering electro-thermal coupling of transmission lines is proposed in this paper. Combined with the dynamic thermal rating technology and energy forecasting, the approach can ...A static security assessment approach considering electro-thermal coupling of transmission lines is proposed in this paper. Combined with the dynamic thermal rating technology and energy forecasting, the approach can track both the electrical variables and transmission lines’ temperature varying trajectory under anticipated contingencies. Accordingly, it identifies the serious contingencies by transmission lines’ temperature violation rather than its power flow, in this case the time margin of temperature rising under each serious contingency can be provided to operators as warning information and some unnecessary security control can also be avoided. Finally, numerical simulations are carried out to testify the validity of the proposed approach.展开更多
In this paper, a new idea of reconfigurable 3/6 dB branch line coupler is proposed. The proposed coupler is tuned through a simple open and short circuit at the coupler’s branches’ edges. At the short edges case, a ...In this paper, a new idea of reconfigurable 3/6 dB branch line coupler is proposed. The proposed coupler is tuned through a simple open and short circuit at the coupler’s branches’ edges. At the short edges case, a 3 dB branch line coupler is obtained. In this case, the coupler’s branches are considered as microstrip transmission lines with 0.3 mm slot width which is etched in each coupler’s branch. At the open edges case, the coupler’s branches are considered as asymmetric coupled microstrip lines. In this case, a 6 dB branch line coupler is obtained. Both CST and IE3D simulators are used to optimize the reconfigurable 3/6 dB branch line coupler dimensions. As a prototypes, two BLCs are designed, analyzed and tested at the “on” and “off” states at 2.5 GHz. The measured S-parameters confirm the proposed concept of the reconfigurable 3/6 dB branch line coupler.展开更多
This research presents a multi-band hybrid mobile phone antenna based on electromagnetic coupling,which can be applied to mobile handheld devices, occupying a small board space of 39.7 mm × 15.6 mm on the system ...This research presents a multi-band hybrid mobile phone antenna based on electromagnetic coupling,which can be applied to mobile handheld devices, occupying a small board space of 39.7 mm × 15.6 mm on the system circuit board. By adding resonant and coupled branch instead of multi-feed on the traditional bent antenna,this design provides four wide operating bands of 0.772—0.998 GHz, 1.540—1.600 GHz, 1.680—2.270 GHz and2.300—2.690 GHz with the hybrid feature of planar inverted-F antenna(PIFA), L-shape, U-shape and S-shape structures, which cover nine-band, i.e., GSM850, GSM900, GPS1575, DCS1800, PCS1900, IMT200, LTE2300,LTE2600 and Blue Tooth/Wi-Fi. Ansoft software HFSS is used in this research to make the antenna performance better and the operating principle of the proposed antenna is described in detail. Result of simulation reveals that the maximum gains of these four wide bands are 2.20,-0.99, 4.01 and 4.05 dBi, respectively. Moreover, this research also tests the return loss(S11) of the fabricated antenna with the vector network analyzer and the result is in accordance with the simulation result on the whole. There are four wide resonant frequencies which cover nine-band of wireless wide area network(WWAN), wireless local area network(WLAN) and long term evolution(LTE), when the available bandwidth is better than 6 d Bi return loss.展开更多
A quasi 0-dB coupler composed of a composite right-/left-handed transmission line (CRLH TL) and a conventional right-handed transmission line (RH TL) is presented. This coupler is shown to exhibit broad bandwidth and ...A quasi 0-dB coupler composed of a composite right-/left-handed transmission line (CRLH TL) and a conventional right-handed transmission line (RH TL) is presented. This coupler is shown to exhibit broad bandwidth and tight coupling char- acteristics. The circuit model and S-parameter results are also demonstrated. Another coupler with properly chosen loaded lumped-elements LL and CL in the CRLH TL is proposed to gain further understanding of the coupling mechanism. By adjusting the spacing between the CRLH TL and RH TL from 8 mm to 0.2 mm, it can be shown that backward coupling occurs in the left-handed region.展开更多
The access to electricity in rural areas is extremely limited, but it is crucial for all citizens. The population in rural areas of sub-Saharan African (SSA) countries is generally low, making it economically unfeasib...The access to electricity in rural areas is extremely limited, but it is crucial for all citizens. The population in rural areas of sub-Saharan African (SSA) countries is generally low, making it economically unfeasible to implement traditional rural electrification (CRE) projects due to the high cost of establishing the necessary distribution infrastructure. To address this cost issue, one alternative technology for rural electrification (URE) that can be explored is the Capacitor Coupled Substation (CCS) technology. CCS is a cost-effective solution for supplying electricity to rural areas. The research is necessitated by the need to offer a cost-effective technology for supplying electricity to sparsely populated communities. This paper examines the impact on the transmission network when a 400 kV/400V CCS is connected to it. The system response when a CCS is connected to the network was modeled using MATLAB/Si-mulink. The results, based on the fixed load of 80 kW, showed negligible interference on the transmission line voltage. However, there was minor impact on the parameters downstream of the tapping point. These findings were further supported by introducing a fault condition to the CCS, which showed that interferences with the CCS could affect the overall stability of the transmission network downstream of the tapping node, similar to the behavior of an unstable load.展开更多
A directional coupler in a miter bend was designed to monitor the microwave power of the transmission line in an electron cyclotron resonance heating（ECRH） system. It is based on aperture-coupling theory and simulat...A directional coupler in a miter bend was designed to monitor the microwave power of the transmission line in an electron cyclotron resonance heating（ECRH） system. It is based on aperture-coupling theory and simulation of an electromagnetic（EM） field to design and optimize the 140 GHz high-power directional coupler. In addition, we simulated the double-aperture directional coupler by using three-dimensional（3D） EM simulation software, in which the central frequency is 140 GHz, coupling factor is about –70 dB, and directivity is greater than 17 dB. The results show that such a coupler is a viable tool for power measurement in high-power transmission systems.展开更多
The purpose of this review is to summarise the existing literature on the operational systems as to explain the current state of understanding on the coupled operational systems.The review only considers the linear op...The purpose of this review is to summarise the existing literature on the operational systems as to explain the current state of understanding on the coupled operational systems.The review only considers the linear optimisation of the operational systems.Traditionally,the operational systems are classified as decoupled,tightly coupled,and loosely coupled.Lately,the coupled operational systems were classified as systems of time-sensitive and time-insensitive operational cycle,systems employing one mix and different mixes of factors of production,and systems of single-linear,single-linear-fractional,and multi-linear objective.These new classifications extend the knowledge about the linear optimisation of the coupled operational systems and reveal new objective-improving models and new state-of-the-art methodologies never discussed before.Business areas affected by these extensions include product assembly lines,cooperative farming,gas/oil reservoir development,maintenance service throughout multiple facilities,construction via different locations,flights traffic control in aviation,game reserves,and tramp shipping in maritime cargo transport.展开更多
We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with du...We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with dual tunable couplers,where each coupler comprises two 2×2 multimode interferometers and a MZI phase-tuning section.Experimental results demonstrate continuous delay tuning from 0 to 293 ps through synchronized control of coupling coefficients,corresponding to a 4 cm path difference between interferometer arms.The measured delay range exhibits excellent agreement with theoretical predictions derived from ODL waveguide parameters.This result addresses critical challenges in integrated photonic systems that require precise temporal control,particularly for applications in optical communications and quantum information processing,where a wide tuning range is paramount.展开更多
In theory,due to the fact that the grounding wire PE of wind turbine and the N-line(directly grounded)of the Y-shaped wiring on the low-voltage side of the box-type transformer share the grounding body,when the wind t...In theory,due to the fact that the grounding wire PE of wind turbine and the N-line(directly grounded)of the Y-shaped wiring on the low-voltage side of the box-type transformer share the grounding body,when the wind turbine is struck by lightning,the lightning current is directly conducted to the N-line on the low-voltage side of the box-type transformer(invasion mode of transformer synonym end).At the same time,conducted overvoltage pulse is generated in the three-phase winding on the low-voltage side,and coupled to the high-voltage side of the box-type transformer(Δconnection)to generate coupling overvoltage pulse.After investigation,the existing regulations on the tripping rate of power lines have not taken into account the impact of wind turbines being struck by lightning on line tripping,and the mechanism is still unclear.In order to further analyze the causes of lightning tripping of collection line circuit breakers in wind farms,it is necessary to study the physical process of how lightning current is conducted(coupled)to the collection line through the box-type transformer after lightning strikes on the wind turbines.In this paper,the test method of"conduction and coupling test of lightning current invading transformer N-line",and the waveform parameters(polarity,phase,amplitude,and transformation ratio)of the primary and secondary windings of the box-type transformer when lightning current invades the transformer N-line are introduced.It can provide assistance for operation and maintenance personnel to analyze the reasons for lightning tripping of 35 kV line circuit breakers in wind farms.展开更多
The exploration for renewable and clean energies has become crucial due to environmental issues such as global warming and the energy crisis. In recent years,floating offshore wind turbines(FOWTs) have attracted a con...The exploration for renewable and clean energies has become crucial due to environmental issues such as global warming and the energy crisis. In recent years,floating offshore wind turbines(FOWTs) have attracted a considerable amount of attention as a means to exploit steady and strong wind sources available in deep-sea areas. In this study, the coupled aero-hydrodynamic characteristics of a spar-type 5-MW wind turbine are analyzed. An unsteady actuator line model(UALM) coupled with a twophase computational fluid dynamics solver naoe-FOAM-SJTU is applied to solve three-dimensional Reynolds-averaged NavierStokes equations. Simulations with different complexities are performed. First, the wind turbine is parked. Second, the impact of the wind turbine is simplified into equivalent forces and moments. Third, fully coupled dynamic analysis with wind and wave excitation is conducted by utilizing the UALM. From the simulation, aerodynamic forces, including the unsteady aerodynamic power and thrust, can be obtained, and hydrodynamic responses such as the six-degrees-of-freedom motions of the floating platform and the mooring tensions are also available. The coupled responses of the FOWT for cases of different complexities are analyzed based on the simulation results. Findings indicate that the coupling effects between the aerodynamics of the wind turbine and the hydrodynamics of the floating platform are obvious. The aerodynamic loads have a significant effect on the dynamic responses of the floating platform, and the aerodynamic performance of the wind turbine has highly unsteady characteristics due to the motions of the floating platform. A spar-type FOWT consisting of NREL-5-MW baseline wind turbine and OC3-Hywind platform system is investigated. The aerodynamic forces can be obtained by the UALM. The 6 DoF motions and mooring tensions are predicted by the naoe-FOAM-SJTU. To research the coupling effects between the aerodynamics of the wind turbine and the hydrodynamics of the floating platform, simulations with different complexities are performed. Fully coupled aero-hydrodynamic characteristics of FOWTs, including aerodynamic loads, wake vortex, motion responses, and mooring tensions, are compared and analyzed.展开更多
基金funding support from the National Natural Science Foundation of China(Grants Nos.42330708 and 42302329)the Graduate Innovation Research Program of Jilin University(Grant No.2024CX118).
文摘Uneven frost heave deformation can shorten the operational lifespan of foundation engineering.Clarifying the mechanisms of uneven frost heave facilitates the targeted mitigation of frost damage.This study focused on a water conveyance channel in Jilin Province,northern China,and found after monitoring that the frost heave at the channel bottom lining exceeded that at the crest by 44.5 mm,with the freezing temperature at the bottom being over 2℃lower than that at the crest.Soil columns with an initial gravimetric moisture content of 12%,16%,18%,and 20%were then prepared.The effects of temperature and moisture content on frost heave were analyzed under two freezing conditions(-5℃and-10℃)through unidirectional freezing tests.A coupled thermo-hydro-mechanical(THM)frost heave model,validated by the test results,was further established.In the soil with an initial moisture content of 20%,the formation of ice lenses associated with substantial water migration contributed to a large temperature gradient,which can jointly induce frost heave.Under the-10℃condition,the temperature gradient in the soil column with a 20%initial moisture content reached 0.84℃/cm,the total water migration reached 10.72%,and the frost heave deformation was 1.86 mm.The THM coupling results indicated that,under the interaction of a large temperature gradient and moisture accumulation,the volumetric ice content remained high in the bottom soil during freezing and peaked at 0.36.The frost damage to the bottom soil was severe,and the maximum deformation reached 57 mm.
文摘This paper deals with the design of bidirectional coupler for broadband power line communication and the impedance matching technique with the power line. This coupler can be used for both transmitting and receiving the data, acting as transceiver. The impedance mismatching problem is also solved here using line trap circuit. The coupler circuit is capable of transmitting or receiving modulated signals with carrier frequency of 15 MHz which can be used for domestic as well as distribution power networks. Laboratory prototype tested using power line network consists of electrical household appliances and results show that the circuit is able to facilitate bidirectional band pass transmission.
文摘The global rise in energy demand, particularly in remote and sparsely populated regions, necessitates innovative and cost-effective electrical distribution solutions. Traditional Rural Electrification (RE) methods, like Conventional Rural Electrification (CRE), have proven economically unfeasible in such areas due to high infrastructure costs and low electricity demand. Consequently, Unconventional Rural Electrification (URE) technologies, such as Capacitor Coupled Substations (CCS), are gaining attention as viable alternatives. This study presents the design and simulation of an 80 kW CCS system, which taps power directly from a 132 kV transmission line to supply low-voltage consumers. The critical components of the CCS, the capacitors are calculated, then a MATLAB/Simulink model with the attained results is executed. Mathematical representation and state-space representation for maintaining the desired tapped voltage area also developed. The research further explores the feasibility and operational performance of this CCS configuration, aiming to address the challenges of rural electrification by offering a sustainable and scalable solution. The results show that the desired value of the tapped voltage can be achieved at any level of High Voltage (HV) with the selection of capacitors that are correctly rated. With an adequately designed control strategy, the research also shows that tapped voltage can be attained under both steady-state and dynamic loads. By leveraging CCS technology, the study demonstrates the potential for delivering reliable electricity to underserved areas, highlighting the system’s practicality and effectiveness in overcoming the limitations of conventional distribution methods.
基金Supported by the National Natural Science Foundation of China under Grant No.51109040
文摘This paper discusses the numerical modeling of the dynamic coupled analysis of the floating platform and mooring/risers using the asynchronous coupling algorithm with the purpose to improve the computational efficiency when multiple lines are connected to the platform. The numerical model of the platform motion simulation in wave is presented. Additionally, how the asynchronous coupling algorithm is implemented during the dynamic coupling analysis is introduced. Through a comparison of the numerical results of our developed model with commercial software for a SPAR platform, the developed numerical model is checked and validated.
基金supported by National Basic Research Program of China(973 Program)(No.2014CB339900)National Natural Science Foundations of China(No.61422103,and 61327806)
文摘This paper reports a novel dual-band coupled-line bandpass filter.Comprising a quadruple-mode coupled-line resonator,this proposed filter could filter signals on two frequency bands.After introducing two varactors,one of the four resonances could be continuously altered by changing the capacitance of the varactors,thus the two frequency bandwidths could be independently tunned.In this paper,the detailed explanation for its operation is given,and the agreement between the expected and practical performance sufficiently confirms the robustness and effectiveness of this proposed filter.
基金the Division of Atmospheric Sciences, National Science Foundation under Grant Nos. ATM-9632390 , ATM-0080088 the National Oceanic and Atmospheric Administration under Grant No.NA03-NES-4400015.
文摘An atmosphere-ocean coupled mesoscale modeling system is developed and used to investigate the interactions between a squall line and the upper ocean observed over the western Paci?c warm pool during the Tropical Ocean/Global Atmosphere Coupled Ocean and Atmosphere Response Experiment (TOGA-COARE). The modeling system is developed by coupling the Advanced Regional Prediction Sys- tem (ARPS) to the Princeton Ocean Model (POM) through precipitation and two-way exchanges of mo- mentum, heat, and moisture across the air-sea interface. The results indicate that the interaction between the squall-line and the upper ocean produced noticeable di?erences in the sensible and latent heat ?uxes, as compared to the uncoupled cases. Precipitation, which is often ignored in air-sea heat ?ux estimates, played a major role in the coupling between the mesoscale convective system and the ocean. Precipitation a?ected the air-sea interaction through both freshwater ?ux and sensible heat ?ux. The former led to the formation of a thin stable ocean layer underneath and behind the precipitating atmospheric convection. The presence of this stable layer resulted in a more signi?cant convection-induced sea surface temperature (SST) change in and behind the precipitation zone. However, convection-induced SST changes do not seem to play an important role in the intsensi?cation of the existing convective system that resulted in the SST change, as the convection quickly moved away from the region of original SST response.
基金supported by the National Natural Science Foundation of China under Grant No.61001027the Fundamental Research Funds for the Central Universities under Grant No.ZYGX2010J046+2 种基金the Research on Millimeter Wave Waveguide-to-Microstrip Transition Technology under Grant No.H04010401W0409100supporting this research by the project of the Study on Electromagnetic Characteristics of Metamaterials under the Grant No.Y02002010401062the Foundation of Study on Characteristic of Chiral Metamaterials sponsored by the School of Physical Electronics,University of Electronic Science and Technology of China
文摘A novel millimeter-wave waveguide-to-microstrip transition based on magnetic-coupling is presented in this paper.The mode conversion of electromagnetic field is realized with the ring strip line of arbitrary shape in the E-plane of rectangular waveguide and the eccentric quasi-coaxial line,which is partially filled with media and consists of outer and inner rectangular conductors.The structure has the advantages of low loss,wide bandwidth,compact structure,and avoiding debug.From 27 GHz to 40 GHz,the experiment results show that the insertion loss is less than 1.2 dB and the return loss is better than 13.5 dB for the back-to-back transition with semicircle ring strip lines.
基金supported by National Natural Science Foundations of China (No.61422103, and No.61671084)National Key Basic Research Program of China (973 Program) (No.2014CB339900)BUPT Excellent Ph.D. Students Foundation (CX2016303)
文摘A planar circuit structure, which is based on three cascaded pairs of coupled lines, an open stub, and an isolation resistor, is proposed in this paper to design a compact dual.band balun with high isolation. This circuit features equal power division with out of phase, all ports matching, high isolation between two outputs, compact structure, and inherent impedance transformation. The closedform design equations are derived based on the traditional transmission.line theory and even.(odd.) mode analysis. A practical dual.band balun, which operates at 0.9/1.8GHz, is designed and fabricated to validate the function of equal power division with out of phase and high isolation between two outputs. The consistency between the simulated and measured results verify the design theory.
文摘For the first lime, the pressure and flow pulse wave propagation phenomenon is studied in this paper on the basis of he cardiovascular dynamic coupling. E(t)-R model is adopted for left ventricle and T-Y tube model for systemic arteries. Furthermore, impulse response method and Fourier analysis method are employed After reasonable cardiovascular parameters and their value have been selected, the pressure and flow waveforms ape obtained at any poing along the systemic arteries. The results fit measured data well. In addition, the influences of cardiovascular parameters on pulse wave propagation are studied. The work is useful in practice.
文摘This paper presents a dual band Band Pass Filter (BPF) operating at both the downlink and uplink frequency bands for Ku-band satellite applications. The commonly used frequency band in mobile communications satellites is the Ku-band. These mobile satellite systems help connect remote regions, vehicles, ships, people and aircraft to other parts of the world and/or other mobile or stationary communications units, in addition to serving as navigation systems. The structure of the proposed filter is based on parallel coupled microstrip lines and four sections are used. Tuning the two operational bands can be achieved using two open-circuited stubs at the first and last sections of the parallel coupled microstrip lines. The proposed filter is adjusted to operate at 12.54 GHz and 14.14 GHz for downlink and uplink bands, respectively. The proposed dual band BPF is fabricated, measured, and good agreement is obtained between simulated and measured results.
文摘A static security assessment approach considering electro-thermal coupling of transmission lines is proposed in this paper. Combined with the dynamic thermal rating technology and energy forecasting, the approach can track both the electrical variables and transmission lines’ temperature varying trajectory under anticipated contingencies. Accordingly, it identifies the serious contingencies by transmission lines’ temperature violation rather than its power flow, in this case the time margin of temperature rising under each serious contingency can be provided to operators as warning information and some unnecessary security control can also be avoided. Finally, numerical simulations are carried out to testify the validity of the proposed approach.
文摘In this paper, a new idea of reconfigurable 3/6 dB branch line coupler is proposed. The proposed coupler is tuned through a simple open and short circuit at the coupler’s branches’ edges. At the short edges case, a 3 dB branch line coupler is obtained. In this case, the coupler’s branches are considered as microstrip transmission lines with 0.3 mm slot width which is etched in each coupler’s branch. At the open edges case, the coupler’s branches are considered as asymmetric coupled microstrip lines. In this case, a 6 dB branch line coupler is obtained. Both CST and IE3D simulators are used to optimize the reconfigurable 3/6 dB branch line coupler dimensions. As a prototypes, two BLCs are designed, analyzed and tested at the “on” and “off” states at 2.5 GHz. The measured S-parameters confirm the proposed concept of the reconfigurable 3/6 dB branch line coupler.
基金the Fund of Standardization for Technical Requirements of Industrial Networking and Test Verification System(No.2015ZXB004)
文摘This research presents a multi-band hybrid mobile phone antenna based on electromagnetic coupling,which can be applied to mobile handheld devices, occupying a small board space of 39.7 mm × 15.6 mm on the system circuit board. By adding resonant and coupled branch instead of multi-feed on the traditional bent antenna,this design provides four wide operating bands of 0.772—0.998 GHz, 1.540—1.600 GHz, 1.680—2.270 GHz and2.300—2.690 GHz with the hybrid feature of planar inverted-F antenna(PIFA), L-shape, U-shape and S-shape structures, which cover nine-band, i.e., GSM850, GSM900, GPS1575, DCS1800, PCS1900, IMT200, LTE2300,LTE2600 and Blue Tooth/Wi-Fi. Ansoft software HFSS is used in this research to make the antenna performance better and the operating principle of the proposed antenna is described in detail. Result of simulation reveals that the maximum gains of these four wide bands are 2.20,-0.99, 4.01 and 4.05 dBi, respectively. Moreover, this research also tests the return loss(S11) of the fabricated antenna with the vector network analyzer and the result is in accordance with the simulation result on the whole. There are four wide resonant frequencies which cover nine-band of wireless wide area network(WWAN), wireless local area network(WLAN) and long term evolution(LTE), when the available bandwidth is better than 6 d Bi return loss.
基金Project supported by the National Basic Research Program (973) of China (No. 2004CB719802) and the National Natural Science Foun-dation of China (No. 50477048)
文摘A quasi 0-dB coupler composed of a composite right-/left-handed transmission line (CRLH TL) and a conventional right-handed transmission line (RH TL) is presented. This coupler is shown to exhibit broad bandwidth and tight coupling char- acteristics. The circuit model and S-parameter results are also demonstrated. Another coupler with properly chosen loaded lumped-elements LL and CL in the CRLH TL is proposed to gain further understanding of the coupling mechanism. By adjusting the spacing between the CRLH TL and RH TL from 8 mm to 0.2 mm, it can be shown that backward coupling occurs in the left-handed region.
文摘The access to electricity in rural areas is extremely limited, but it is crucial for all citizens. The population in rural areas of sub-Saharan African (SSA) countries is generally low, making it economically unfeasible to implement traditional rural electrification (CRE) projects due to the high cost of establishing the necessary distribution infrastructure. To address this cost issue, one alternative technology for rural electrification (URE) that can be explored is the Capacitor Coupled Substation (CCS) technology. CCS is a cost-effective solution for supplying electricity to rural areas. The research is necessitated by the need to offer a cost-effective technology for supplying electricity to sparsely populated communities. This paper examines the impact on the transmission network when a 400 kV/400V CCS is connected to it. The system response when a CCS is connected to the network was modeled using MATLAB/Si-mulink. The results, based on the fixed load of 80 kW, showed negligible interference on the transmission line voltage. However, there was minor impact on the parameters downstream of the tapping point. These findings were further supported by introducing a fault condition to the CCS, which showed that interferences with the CCS could affect the overall stability of the transmission network downstream of the tapping node, similar to the behavior of an unstable load.
基金supported by International S&T Cooperation Program of China(No.2011DFA63190)National Natural Science Foundation of China(No.11275045)the International Cooperation Plan Program of Sichuan Province,China(No.M1701040113HH0001)
文摘A directional coupler in a miter bend was designed to monitor the microwave power of the transmission line in an electron cyclotron resonance heating（ECRH） system. It is based on aperture-coupling theory and simulation of an electromagnetic（EM） field to design and optimize the 140 GHz high-power directional coupler. In addition, we simulated the double-aperture directional coupler by using three-dimensional（3D） EM simulation software, in which the central frequency is 140 GHz, coupling factor is about –70 dB, and directivity is greater than 17 dB. The results show that such a coupler is a viable tool for power measurement in high-power transmission systems.
文摘The purpose of this review is to summarise the existing literature on the operational systems as to explain the current state of understanding on the coupled operational systems.The review only considers the linear optimisation of the operational systems.Traditionally,the operational systems are classified as decoupled,tightly coupled,and loosely coupled.Lately,the coupled operational systems were classified as systems of time-sensitive and time-insensitive operational cycle,systems employing one mix and different mixes of factors of production,and systems of single-linear,single-linear-fractional,and multi-linear objective.These new classifications extend the knowledge about the linear optimisation of the coupled operational systems and reveal new objective-improving models and new state-of-the-art methodologies never discussed before.Business areas affected by these extensions include product assembly lines,cooperative farming,gas/oil reservoir development,maintenance service throughout multiple facilities,construction via different locations,flights traffic control in aviation,game reserves,and tramp shipping in maritime cargo transport.
基金supported by the National Natural Science Foundation of China(Grant Nos.12192251,12334014,12404378,92480001,12134001,12174113,12174107,12474325,12404379,and 12474378)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301403)+1 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Fundamental Research Funds for the Central Universities,the Engineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(Grant No.2023nmc005).
文摘We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with dual tunable couplers,where each coupler comprises two 2×2 multimode interferometers and a MZI phase-tuning section.Experimental results demonstrate continuous delay tuning from 0 to 293 ps through synchronized control of coupling coefficients,corresponding to a 4 cm path difference between interferometer arms.The measured delay range exhibits excellent agreement with theoretical predictions derived from ODL waveguide parameters.This result addresses critical challenges in integrated photonic systems that require precise temporal control,particularly for applications in optical communications and quantum information processing,where a wide tuning range is paramount.
基金Supported by the Real-time Monitoring of Strong Electromagnetic Pulse Protection(Lightning)Effect and Grounding Resistance for Guangdong Yuedian Zhuhai Biqing Bay Sea Wind Farm(SFC/ZHW-ZX-FW-24-023)the Research on Key Technologies of Lightning Intelligent Protection System for Guangdong Energy Hehe Sea Wind Farm(SFC/QZW-ZX-XF-24-020).
文摘In theory,due to the fact that the grounding wire PE of wind turbine and the N-line(directly grounded)of the Y-shaped wiring on the low-voltage side of the box-type transformer share the grounding body,when the wind turbine is struck by lightning,the lightning current is directly conducted to the N-line on the low-voltage side of the box-type transformer(invasion mode of transformer synonym end).At the same time,conducted overvoltage pulse is generated in the three-phase winding on the low-voltage side,and coupled to the high-voltage side of the box-type transformer(Δconnection)to generate coupling overvoltage pulse.After investigation,the existing regulations on the tripping rate of power lines have not taken into account the impact of wind turbines being struck by lightning on line tripping,and the mechanism is still unclear.In order to further analyze the causes of lightning tripping of collection line circuit breakers in wind farms,it is necessary to study the physical process of how lightning current is conducted(coupled)to the collection line through the box-type transformer after lightning strikes on the wind turbines.In this paper,the test method of"conduction and coupling test of lightning current invading transformer N-line",and the waveform parameters(polarity,phase,amplitude,and transformation ratio)of the primary and secondary windings of the box-type transformer when lightning current invades the transformer N-line are introduced.It can provide assistance for operation and maintenance personnel to analyze the reasons for lightning tripping of 35 kV line circuit breakers in wind farms.
文摘The exploration for renewable and clean energies has become crucial due to environmental issues such as global warming and the energy crisis. In recent years,floating offshore wind turbines(FOWTs) have attracted a considerable amount of attention as a means to exploit steady and strong wind sources available in deep-sea areas. In this study, the coupled aero-hydrodynamic characteristics of a spar-type 5-MW wind turbine are analyzed. An unsteady actuator line model(UALM) coupled with a twophase computational fluid dynamics solver naoe-FOAM-SJTU is applied to solve three-dimensional Reynolds-averaged NavierStokes equations. Simulations with different complexities are performed. First, the wind turbine is parked. Second, the impact of the wind turbine is simplified into equivalent forces and moments. Third, fully coupled dynamic analysis with wind and wave excitation is conducted by utilizing the UALM. From the simulation, aerodynamic forces, including the unsteady aerodynamic power and thrust, can be obtained, and hydrodynamic responses such as the six-degrees-of-freedom motions of the floating platform and the mooring tensions are also available. The coupled responses of the FOWT for cases of different complexities are analyzed based on the simulation results. Findings indicate that the coupling effects between the aerodynamics of the wind turbine and the hydrodynamics of the floating platform are obvious. The aerodynamic loads have a significant effect on the dynamic responses of the floating platform, and the aerodynamic performance of the wind turbine has highly unsteady characteristics due to the motions of the floating platform. A spar-type FOWT consisting of NREL-5-MW baseline wind turbine and OC3-Hywind platform system is investigated. The aerodynamic forces can be obtained by the UALM. The 6 DoF motions and mooring tensions are predicted by the naoe-FOAM-SJTU. To research the coupling effects between the aerodynamics of the wind turbine and the hydrodynamics of the floating platform, simulations with different complexities are performed. Fully coupled aero-hydrodynamic characteristics of FOWTs, including aerodynamic loads, wake vortex, motion responses, and mooring tensions, are compared and analyzed.
