As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of ai...As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of aircraft structures. The assessment of electromagnetic SE for Slotted Composite Structures(SCSs) is particularly challenging due to their complex geometries and there remains a lack of suitable models for accurately predicting the SE performance of these intricate configurations. To address this issue, this paper introduces SCS-Net, a Deep Neural Network (DNN) method designed to accurately predict the SE of SCS. This method considers the impacts of various structural parameters, material properties and incident wave parameters on the SE of SCSs. In order to better model the SCS, an improved Nicolson-Ross-Weir (NRW) method is introduced in this paper to provide an equivalent flat structure for the SCS and to calculate the electromagnetic parameters of the equivalent structure. Additionally, the prediction of SE via DNNs is limited by insufficient test data, which hinders support for large-sample training. To address the issue of limited measured data, this paper develops a Measurement-Computation Fusion (MCF) dataset construction method. The predictions based on the simulation results show that the proposed method maintains an error of less than 0.07 dB within the 8–10 GHz frequency range. Furthermore, a new loss function based on the weighted L1-norm is established to improve the prediction accuracy for these parameters. Compared with traditional loss functions, the new loss function reduces the maximum prediction error for equivalent electromagnetic parameters by 47%. This method significantly improves the prediction accuracy of SCS-Net for measured data, with a maximum improvement of 23.88%. These findings demonstrate that the proposed method enables precise SE prediction and design for composite structures while reducing the number of test samples needed.展开更多
Intent detection and slot filling are two important components of natural language understanding.Because their relevance,joint training is often performed to improve performance.Existing studies mostly use a joint mod...Intent detection and slot filling are two important components of natural language understanding.Because their relevance,joint training is often performed to improve performance.Existing studies mostly use a joint model of multi-intent detection and slot-filling with unidirectional interaction,which improves the overall performance of the model by fusing the intent information in the slot-filling part.On this basis,in order to further improve the overall performance of the model by exploiting the correlation between the two,this paper proposes a joint multi-intent detection and slot-filling model based on a bidirectional interaction structure,which fuses the intent encoding information in the encoding part of slot filling and fuses the slot decoding information in the decoding part of intent detection.Experimental results on two public multi-intent joint training datasets,MixATIS and MixSNIPS,show that the bidirectional interaction structure proposed in this paper can effectively improve the performance of the joint model.In addition,in order to verify the generalization of the bidirectional interaction structure between intent and slot,a joint model for single-intent scenarios is proposed on the basis of the model in this paper.This model also achieves excellent performance on two public single-intent joint training datasets,CAIS and SNIPS.展开更多
To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,u...To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,utilizing the reflection of the grating to achieve the electromagnetic-like induced transparency effect at different wavelengths.The high slope characteristics of the EIT-like effect enabled a higher quality factor and sensitivity.The transmission principle of the structure was analyzed using the transmission matrix method,and the transmission spectrum and mode field distribution were simulated using the finite-difference time-domain(FDTD)method,and the device structure parameters were adjusted for optimization.Simulation results show that the proposed structure achieves an EIT-like effect with a quality factor of 59267.5.In the analysis of refractive index sensing characteristics,the structure exhibits a sensitivity of 408.57 nm/RIU and a detection limit of 6.23×10^(-5) RIU.Therefore,the proposed structure achieved both a high quality factor and refractive index sensitivity,demonstrating excellent sensing performance for applications in environmental monitoring,biomedical fields,and other areas with broad market potential.展开更多
Airports around the world commonly face challenges in managing airport slot allocation.Effective management of limited slot resources by civil aviation authority often requires redistributing requested slots among air...Airports around the world commonly face challenges in managing airport slot allocation.Effective management of limited slot resources by civil aviation authority often requires redistributing requested slots among airlines.The allocation process must operate within the prescribed capacity limits of the airport while adhering to established priorities and regulations.Additionally,ensuring market fairness is a key objective,as the value of airport slots plays a significant role in the adjustment process.This transforms the traditional time-shift-based problem into a complex multi-objective optimization problem.Addressing such complications is of significant importance to airlines,airports,and passengers alike.Due to the complexity of fairness metrics,traditional integer programming models encounter difficulties in finding effective solutions.This study proposes a neighborhood search strategy to tackle the single airport slot allocation,making it adaptable to both static and rolling capacity scenarios.Two Genetic Algorithms(GAs)are introduced,corresponding to time adjustment and sequence adjustment strategies,respectively.The GA based on the time adjustment strategy demonstrates high robustness,while the sequence adjustment strategy builds upon this GA to develop a simple heuristic algorithm that offers rapid convergence.Case studies conducted at seven airports in China confirm that all three algorithms yield high-quality adjustment solutions suitable for the majority of applications.Further,Pareto analysis reveals that these algorithms effectively balance the adjustment shifts and fairness metrics,demonstrating high practical value and broad applicability.展开更多
In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant ...In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant effects upon the traffic delay per- formance. This article proposes models to analyze the relationships among frame length, bandwidth assignment (assigned time slot count), time slot location in frame, and traffic delay performance for traffics of constant bit rate (CBR) and variable bit rate (...展开更多
A rigorous analysis of a broad wall slot coupler composed of two crossed rectangular waveguides by using FDTD method is presented. Two types of slots, a longitudinal/transverse slot and a centered-inclined slot, are a...A rigorous analysis of a broad wall slot coupler composed of two crossed rectangular waveguides by using FDTD method is presented. Two types of slots, a longitudinal/transverse slot and a centered-inclined slot, are analyzed. Coupling slot characteristics are obtained, including scattering parameters and the resonant length for different waveguide dimensions and frequencies. The numerical results are all in good agreement with those by the method of moments. A coupler system with a short circuit port is also analyzed to help designing the slot array.展开更多
A differential equation for calculating squeeze-film air damping in slotted plates is developed by modifying the Reynolds equation. A term is added to account for the effect of airflow through the slots on the air dam...A differential equation for calculating squeeze-film air damping in slotted plates is developed by modifying the Reynolds equation. A term is added to account for the effect of airflow through the slots on the air damping of the plate. The end effect of the airflow in the slots is also treated by substituting an effective channel length for the geometric channel length （i. e. the thickness of the plate）..The damping pressure distribution, damping force, and damping force coefficient of the slotted plates can be found by solving the equation under appropriate boundary conditions. With restrictions on the thickness and the lateral dimensions of the slotted plate removed,the equation provides a useful tool for analysing the squeeze-film air damping effect of slotted plates with finite thickness and finite lateral dimensions. For a typical slotted plate structure, the damping force coefficient obtained by this equation agrees well with that generated by ANSYS.展开更多
With the rural concealed communication cable as the study object, the shielding effectiveness of different slot shapes was analyzed by using LBEM （linear boundary element method）. The engineering example results sho...With the rural concealed communication cable as the study object, the shielding effectiveness of different slot shapes was analyzed by using LBEM （linear boundary element method）. The engineering example results showed that for twocore shielded cable, the coupling capacitance of trapezoid slots （asymmetric and symmetric） changed the most, followed by rectangular slots （asymmetric and symmetric）, and the changes of wedge slots were the smallest, but the change tenden- cies were consistent. In addition, with the increase of slot width of different slots, the coupling capacitance of tow-cored shielded cable showed small change.展开更多
Hydraulic slotting can induce drill spray in a gassy,low permeability coal seam.This then influences subsequent gas extraction.This paper describes the drill spray phenomenon from a mechanical perspective and analyzes...Hydraulic slotting can induce drill spray in a gassy,low permeability coal seam.This then influences subsequent gas extraction.This paper describes the drill spray phenomenon from a mechanical perspective and analyzes the effects of water jet damage during slotting.A simulation of the stresses around the drill hole and slot was prepared using FLAC-3D code.It helps explain the induction of drill spray during hydraulic slotting.The stress concentration around the bore increases as the diameter of the hole increases.As the hole enlarges the variation in stress also increases,which introduces an instability into the coal.This allows easy breaking and removal of the coal.Destruction of the coal structure by the water jet is the major factor causing drill spray.Energy stored as either strain or gas pressure is released by the water jet and this causes the coal to fracture and be expelled from the hole.Field tests showed the effect on gas extraction after slotting with drill spray.The concentration of gas increases after drilling.Compared to conventional techniques,the hydraulic slotted bore gives a gas concentration three times higher and has an effective range twice as far.This makes the gas extraction process more efficient and allows reduced construction effort.展开更多
A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were anal...A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were analysed to set up the failure criterion of coal containing water and gas, which could describe the destruction rule of coal containing gas under the hydraulic measures more accurately. Based on the theory of transient flow and fluid grid, the numerical calculation model of turbulence formed by high pressure oscillating water jet was used. With the high speed photography test, dynamic evolution and pulsation characteristics of water jet water analysed which laid a foundation for mechanism analysis of rock damage under water jet. Wave equation of oscillating water jet slotting was established and the mechanism of coal damage by the impact stress wave under oscillation jet was revealed. These provide a new method to study the mechanism of porosity and crack damage under high pressure jet.Fracture criterion by jet slotting was established and mechanism of crack development controlled by crack zone between slots was found. The fractures were induced to extend along pre-set direction,instead of being controlled by original stress field. The model of gas migration through coal seams after the hydraulic measures for grid slotting and fracking was established. The key technology and equipment for grid slotting and fracking with high-pressure oscillating jet were developed and applied to coal mines in Chongqing and Henan in China. The results show that the gas permeability of coal seam is enhanced by three orders of magnitude, efficiency of roadway excavation and mining is improved by more than 57%and the cost of gas control is reduced by 50%.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62101020 and 62141405)the Special Scientific Research Project of Civil Aircraft,China(No.MJZ5-2N22).
文摘As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of aircraft structures. The assessment of electromagnetic SE for Slotted Composite Structures(SCSs) is particularly challenging due to their complex geometries and there remains a lack of suitable models for accurately predicting the SE performance of these intricate configurations. To address this issue, this paper introduces SCS-Net, a Deep Neural Network (DNN) method designed to accurately predict the SE of SCS. This method considers the impacts of various structural parameters, material properties and incident wave parameters on the SE of SCSs. In order to better model the SCS, an improved Nicolson-Ross-Weir (NRW) method is introduced in this paper to provide an equivalent flat structure for the SCS and to calculate the electromagnetic parameters of the equivalent structure. Additionally, the prediction of SE via DNNs is limited by insufficient test data, which hinders support for large-sample training. To address the issue of limited measured data, this paper develops a Measurement-Computation Fusion (MCF) dataset construction method. The predictions based on the simulation results show that the proposed method maintains an error of less than 0.07 dB within the 8–10 GHz frequency range. Furthermore, a new loss function based on the weighted L1-norm is established to improve the prediction accuracy for these parameters. Compared with traditional loss functions, the new loss function reduces the maximum prediction error for equivalent electromagnetic parameters by 47%. This method significantly improves the prediction accuracy of SCS-Net for measured data, with a maximum improvement of 23.88%. These findings demonstrate that the proposed method enables precise SE prediction and design for composite structures while reducing the number of test samples needed.
基金Supported by the National Nature Science Foundation of China(62462037,62462036)Project for Academic and Technical Leader in Major Disciplines in Jiangxi Province(20232BCJ22013)+1 种基金Jiangxi Provincial Natural Science Foundation(20242BAB26017,20232BAB202010)Jiangxi Province Graduate Innovation Fund Project(YC2023-S320)。
文摘Intent detection and slot filling are two important components of natural language understanding.Because their relevance,joint training is often performed to improve performance.Existing studies mostly use a joint model of multi-intent detection and slot-filling with unidirectional interaction,which improves the overall performance of the model by fusing the intent information in the slot-filling part.On this basis,in order to further improve the overall performance of the model by exploiting the correlation between the two,this paper proposes a joint multi-intent detection and slot-filling model based on a bidirectional interaction structure,which fuses the intent encoding information in the encoding part of slot filling and fuses the slot decoding information in the decoding part of intent detection.Experimental results on two public multi-intent joint training datasets,MixATIS and MixSNIPS,show that the bidirectional interaction structure proposed in this paper can effectively improve the performance of the joint model.In addition,in order to verify the generalization of the bidirectional interaction structure between intent and slot,a joint model for single-intent scenarios is proposed on the basis of the model in this paper.This model also achieves excellent performance on two public single-intent joint training datasets,CAIS and SNIPS.
基金supported by Natural Science Foundation of Gansu Province(NO.21JR7RA289)。
文摘To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,utilizing the reflection of the grating to achieve the electromagnetic-like induced transparency effect at different wavelengths.The high slope characteristics of the EIT-like effect enabled a higher quality factor and sensitivity.The transmission principle of the structure was analyzed using the transmission matrix method,and the transmission spectrum and mode field distribution were simulated using the finite-difference time-domain(FDTD)method,and the device structure parameters were adjusted for optimization.Simulation results show that the proposed structure achieves an EIT-like effect with a quality factor of 59267.5.In the analysis of refractive index sensing characteristics,the structure exhibits a sensitivity of 408.57 nm/RIU and a detection limit of 6.23×10^(-5) RIU.Therefore,the proposed structure achieved both a high quality factor and refractive index sensitivity,demonstrating excellent sensing performance for applications in environmental monitoring,biomedical fields,and other areas with broad market potential.
基金supported in part by the National Natural Science Foundation of China(Nos.62167003,52302421)in part by the Diversified Investment Fund of Tianjin,China(No.23JCQNJC00210)。
文摘Airports around the world commonly face challenges in managing airport slot allocation.Effective management of limited slot resources by civil aviation authority often requires redistributing requested slots among airlines.The allocation process must operate within the prescribed capacity limits of the airport while adhering to established priorities and regulations.Additionally,ensuring market fairness is a key objective,as the value of airport slots plays a significant role in the adjustment process.This transforms the traditional time-shift-based problem into a complex multi-objective optimization problem.Addressing such complications is of significant importance to airlines,airports,and passengers alike.Due to the complexity of fairness metrics,traditional integer programming models encounter difficulties in finding effective solutions.This study proposes a neighborhood search strategy to tackle the single airport slot allocation,making it adaptable to both static and rolling capacity scenarios.Two Genetic Algorithms(GAs)are introduced,corresponding to time adjustment and sequence adjustment strategies,respectively.The GA based on the time adjustment strategy demonstrates high robustness,while the sequence adjustment strategy builds upon this GA to develop a simple heuristic algorithm that offers rapid convergence.Case studies conducted at seven airports in China confirm that all three algorithms yield high-quality adjustment solutions suitable for the majority of applications.Further,Pareto analysis reveals that these algorithms effectively balance the adjustment shifts and fairness metrics,demonstrating high practical value and broad applicability.
基金National Natural Science Foundation of China (60532030)National Natural Science Foundation for Distinguished Young Scholars (60625102)
文摘In digital video broadcasting and return channel via satellite (DVB-RCS) systems, the time slot location assigned to a given traffic in multiple frequency-time division multiple access (MF-TDMA) frame has significant effects upon the traffic delay per- formance. This article proposes models to analyze the relationships among frame length, bandwidth assignment (assigned time slot count), time slot location in frame, and traffic delay performance for traffics of constant bit rate (CBR) and variable bit rate (...
文摘A rigorous analysis of a broad wall slot coupler composed of two crossed rectangular waveguides by using FDTD method is presented. Two types of slots, a longitudinal/transverse slot and a centered-inclined slot, are analyzed. Coupling slot characteristics are obtained, including scattering parameters and the resonant length for different waveguide dimensions and frequencies. The numerical results are all in good agreement with those by the method of moments. A coupler system with a short circuit port is also analyzed to help designing the slot array.
文摘A differential equation for calculating squeeze-film air damping in slotted plates is developed by modifying the Reynolds equation. A term is added to account for the effect of airflow through the slots on the air damping of the plate. The end effect of the airflow in the slots is also treated by substituting an effective channel length for the geometric channel length （i. e. the thickness of the plate）..The damping pressure distribution, damping force, and damping force coefficient of the slotted plates can be found by solving the equation under appropriate boundary conditions. With restrictions on the thickness and the lateral dimensions of the slotted plate removed,the equation provides a useful tool for analysing the squeeze-film air damping effect of slotted plates with finite thickness and finite lateral dimensions. For a typical slotted plate structure, the damping force coefficient obtained by this equation agrees well with that generated by ANSYS.
基金Supported by the Science and Technology Program of the Education Department of Shaanxi Provincial Government(09JK378)the Key Scientific Research Fund of Shaanxi University of Technology(SLGKY12-02)~~
文摘With the rural concealed communication cable as the study object, the shielding effectiveness of different slot shapes was analyzed by using LBEM （linear boundary element method）. The engineering example results showed that for twocore shielded cable, the coupling capacitance of trapezoid slots （asymmetric and symmetric） changed the most, followed by rectangular slots （asymmetric and symmetric）, and the changes of wedge slots were the smallest, but the change tenden- cies were consistent. In addition, with the increase of slot width of different slots, the coupling capacitance of tow-cored shielded cable showed small change.
基金support provided by the State Key Basic Research Program of China(No.2011CB201205)the National Natural Science Foundation of China(No.51074161)+3 种基金the National Science and Technology Support Program(No.2012BAK04B07)the project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.CXZZ12_0958)the Open Foundation project of Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines(201201)support for the field application and tests of the technology
文摘Hydraulic slotting can induce drill spray in a gassy,low permeability coal seam.This then influences subsequent gas extraction.This paper describes the drill spray phenomenon from a mechanical perspective and analyzes the effects of water jet damage during slotting.A simulation of the stresses around the drill hole and slot was prepared using FLAC-3D code.It helps explain the induction of drill spray during hydraulic slotting.The stress concentration around the bore increases as the diameter of the hole increases.As the hole enlarges the variation in stress also increases,which introduces an instability into the coal.This allows easy breaking and removal of the coal.Destruction of the coal structure by the water jet is the major factor causing drill spray.Energy stored as either strain or gas pressure is released by the water jet and this causes the coal to fracture and be expelled from the hole.Field tests showed the effect on gas extraction after slotting with drill spray.The concentration of gas increases after drilling.Compared to conventional techniques,the hydraulic slotted bore gives a gas concentration three times higher and has an effective range twice as far.This makes the gas extraction process more efficient and allows reduced construction effort.
基金supported by the National Natural Science Foundation of China(Nos.51374258,51504046,51404045)Program for Changjiang Scholars and Innovative Research Team in University of China(No.IRT13043)the National Basic Research Program of China(No.2014CB239206)
文摘A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were analysed to set up the failure criterion of coal containing water and gas, which could describe the destruction rule of coal containing gas under the hydraulic measures more accurately. Based on the theory of transient flow and fluid grid, the numerical calculation model of turbulence formed by high pressure oscillating water jet was used. With the high speed photography test, dynamic evolution and pulsation characteristics of water jet water analysed which laid a foundation for mechanism analysis of rock damage under water jet. Wave equation of oscillating water jet slotting was established and the mechanism of coal damage by the impact stress wave under oscillation jet was revealed. These provide a new method to study the mechanism of porosity and crack damage under high pressure jet.Fracture criterion by jet slotting was established and mechanism of crack development controlled by crack zone between slots was found. The fractures were induced to extend along pre-set direction,instead of being controlled by original stress field. The model of gas migration through coal seams after the hydraulic measures for grid slotting and fracking was established. The key technology and equipment for grid slotting and fracking with high-pressure oscillating jet were developed and applied to coal mines in Chongqing and Henan in China. The results show that the gas permeability of coal seam is enhanced by three orders of magnitude, efficiency of roadway excavation and mining is improved by more than 57%and the cost of gas control is reduced by 50%.
