We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio th...We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .展开更多
Methods for the approximation of solution of nonlinear system of equations often fail when the Jacobians of the systems are singular at iteration points. In this paper, multi-step families of quadrature based iterativ...Methods for the approximation of solution of nonlinear system of equations often fail when the Jacobians of the systems are singular at iteration points. In this paper, multi-step families of quadrature based iterative methods for approximating the solution of nonlinear system of equations with singular Jacobian are developed using decomposition technique. The methods proposed in this study are of convergence order , and require only the evaluation of first-order Frechet derivative per iteration. The approximate solutions generated by the proposed iterative methods in this paper compared with some existing contemporary methods in literature, show that methods developed herein are efficient and adequate in approximating the solution of nonlinear system of equations whose Jacobians are singular and non-singular at iteration points.展开更多
AIM: To establish an ultrasonographic classification based on a large sample of patients with confirmed hepatic alveolar echinococcosis(AE).METHODS: Clinical data and ultrasonography(US) findings of 185 patients(100 m...AIM: To establish an ultrasonographic classification based on a large sample of patients with confirmed hepatic alveolar echinococcosis(AE).METHODS: Clinical data and ultrasonography(US) findings of 185 patients(100 males; 85 females; mean age at diagnosis: 51.4 ± 17.6 years; mean age at time of US examination: 58.7 ± 18.2 years) were retrospectively reviewed with respect to the US morphology of hepatic AE lesions. The sonomorphological findings were grouped according to a five-part classification scheme.RESULTS: Application of the new classification resulted in the following distribution of sonomorphological patterns among the patients examined: hailstorm(54.1%); pseudocystic(13.5%); ossification(13.0%); hemangioma-like(8.1%); and metastasis-like(6.5%). Only 4.9% of lesions could not be assigned to a sonomorphological pattern.CONCLUSION: The sonomorphological classification proposed in the present study facilitates the diagnosis,interpretation and comparison of hepatic alveolar echinococcosis in routine practice and in the context of scientific studies.展开更多
This paper deals with multiobjective programming problems with support functions under （G, C, ρ）-convexity assumptions. Not only sufficient but also necessary optimality conditions for this kind of multiobjective p...This paper deals with multiobjective programming problems with support functions under （G, C, ρ）-convexity assumptions. Not only sufficient but also necessary optimality conditions for this kind of multiobjective programming problems are established from a viewpoint of （G, C, ρ）-convexity. When the sufficient conditions are utilized, the corresponding duality theorems are derived for general Mond-Weir type dual program.展开更多
This paper introduces two source models: MAP(Markovian arrival process) model for the traffic with correlation and burst, e.g., voice, video, etc. and PAP(Poisson arrival process) model for the traffic with non-correl...This paper introduces two source models: MAP(Markovian arrival process) model for the traffic with correlation and burst, e.g., voice, video, etc. and PAP(Poisson arrival process) model for the traffic with non-correlation, such as data, etc. Then a movable boundary bandwidth access policy is chosen.Basing on above model, the performance measures, e.g., mean waiting time and loss probability,especially the queue length time distribution are obtained. Finally, a number of numerical results are provided and shown through simulation.展开更多
<div style="text-align:justify;"> Electric field superposition principle and Gauss’s law are the basis of electrostatics. By extended analysis on the electric field lines of a charge, it is shown that...<div style="text-align:justify;"> Electric field superposition principle and Gauss’s law are the basis of electrostatics. By extended analysis on the electric field lines of a charge, it is shown that electric field superposition principle and Gauss’s law are not tenable in some states, involving the electric field of ion atmosphere that is a key concept in Debye-Hückel theory of electrolyte solution and plasma. Unveiling Debye shield, ion atmosphere (Debye spherical layer 1) actually is equivalent to continue to transmit the electric field originated from the central ion, just changing the direction of the electric field. Debye spherical layer 2 and multiple Debye spherical layers generate in the transmission. Due to the effect of the multiple Debye spherical layers of charged particles in the universe, gravitation originates from electric force. </div>展开更多
Extensive excavations at the site of Ashur allowed Olaf Pedersén to reconstruct, to a considerable level of detail, the many archives and libraries in official and private collections that existed at ancient Ashu...Extensive excavations at the site of Ashur allowed Olaf Pedersén to reconstruct, to a considerable level of detail, the many archives and libraries in official and private collections that existed at ancient Ashur through the展开更多
Internet of Things (IoT) is ubiquitous, including objects or devices communicating through heterogenous wireless networks. One of the major challenges in mobile IoT is an efficient vertical handover decision (VHD) tec...Internet of Things (IoT) is ubiquitous, including objects or devices communicating through heterogenous wireless networks. One of the major challenges in mobile IoT is an efficient vertical handover decision (VHD) technique between heterogenous networks for seamless connectivity with constrained resources. The conventional VHD approach is mainly based on received signal strength (RSS). The approach is inefficient for vertical handover, since it always selects the target network with the strongest signal without taking into consideration of factors such as quality of service (QoS), cost, delay, etc. In this paper, we present a hybrid approach by integrating the multi-cri- teria based VHD (MCVHD) technique and an algorithm based on fuzzy logic for efficient VHD among Wi-Fi, Radio and Satellite networks. The MCVHD provides a lightweight solution that aims to achieving seamless connectivity for mobile IoT Edge Gateway over a set of heterogeneous networks. The proposed solution is evaluated in real time using a testbed containing real IoT devices. Further, the testbed is integrated with lightweight and efficient software techniques, e.g., microservices, containers, broker, and Edge/Cloud techniques. The experimental results show that the proposed approach is suitable for an IoT environment and it outperforms the conventional RSS Quality based VHD by minimizing handover failures, unnecessary handovers, handover time and cost of service.展开更多
A practical image reconstruction method for multi-source quantitative photoacoustic tomography （QPAT） is proposed in this work with the consideration of detector response function and limited-view scanning. First, t...A practical image reconstruction method for multi-source quantitative photoacoustic tomography （QPAT） is proposed in this work with the consideration of detector response function and limited-view scanning. First, the correct detector response function, i.e., spa- tim impulse response （SIR） and acousto-electric impulse response （EIR）, is considered for the ultrasonic transducer to accurately model the acoustic measurement; second, acoustic data is only measured near optical sources with meaningful signal-to-noise ratio （SNR）, i.e., the limited-view scanning, which also reduces the data acquisition time for point trans- ducer. However, due to the incomplete limited-view data, a two-step image reconstruction method （i.e., to first reconstruct initial acoustic pressure and then reconstruct optical coef- ficients） no longer applies, since it is neither possible nor necessary to robustly reconstruct initial acoustic pressure with limited-view data. Therefore, here we propose a direct image reconstruction method that incorporates SIR, EIR and limited-view scanning in a coupled opto-acoustic forward model, regularizes the framelet sparsity, and then solves the QPAT alternating direction method of multipliers. nonlinear QPAT data fidelity with tensor problem with Quasi-Newton method based展开更多
现代飞行程序设计受地形、障碍物、空域和飞行性能等多种因素的影响,设计过程中需进行大量针对设计细节有效性的评估工作;设计完毕的飞行程序还需专业的飞行试飞人员进行模拟机和真机试飞,耗费大量的人力、经济成本。如果试飞前缺少针...现代飞行程序设计受地形、障碍物、空域和飞行性能等多种因素的影响,设计过程中需进行大量针对设计细节有效性的评估工作;设计完毕的飞行程序还需专业的飞行试飞人员进行模拟机和真机试飞,耗费大量的人力、经济成本。如果试飞前缺少针对性的分析评估,一方面会增加试飞成本的支出,另一方面也会导致真机试飞环节存在安全隐患。针对上述问题,利用深度强化学习技术,提出一种在满足飞行程序设计规范条件下,面向飞行程序有效性和可行性验证的离场航迹自动生成方法。首先,利用空气动力学原理,建立考虑飞行性能和障碍物超障因素的基本飞行动力学模型,并借助Unity3D引擎构建三维可视化的训练平台;其次,在PyTorch深度学习框架中,利用Mlagents强化学习平台构建航空器在飞行时各个阶段的试飞训练模型,设计包括起飞、转弯、巡航和降落这4个目标的场景和奖励函数。以离场飞行程序试飞为例,采用厦门高崎机场某PBN(Performance Based Navigation)离场程序进行实例训练验证,并利用动态时间规整(DTW)距离量化实际生成航迹与标称航迹之间的偏离度。实验结果显示,偏差度满足飞行程序超障保护区的限制要求。上述训练模型在其他离场程序的实验结果也验证了模型具有较好的泛化能力。展开更多
文摘We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .
文摘Methods for the approximation of solution of nonlinear system of equations often fail when the Jacobians of the systems are singular at iteration points. In this paper, multi-step families of quadrature based iterative methods for approximating the solution of nonlinear system of equations with singular Jacobian are developed using decomposition technique. The methods proposed in this study are of convergence order , and require only the evaluation of first-order Frechet derivative per iteration. The approximate solutions generated by the proposed iterative methods in this paper compared with some existing contemporary methods in literature, show that methods developed herein are efficient and adequate in approximating the solution of nonlinear system of equations whose Jacobians are singular and non-singular at iteration points.
文摘AIM: To establish an ultrasonographic classification based on a large sample of patients with confirmed hepatic alveolar echinococcosis(AE).METHODS: Clinical data and ultrasonography(US) findings of 185 patients(100 males; 85 females; mean age at diagnosis: 51.4 ± 17.6 years; mean age at time of US examination: 58.7 ± 18.2 years) were retrospectively reviewed with respect to the US morphology of hepatic AE lesions. The sonomorphological findings were grouped according to a five-part classification scheme.RESULTS: Application of the new classification resulted in the following distribution of sonomorphological patterns among the patients examined: hailstorm(54.1%); pseudocystic(13.5%); ossification(13.0%); hemangioma-like(8.1%); and metastasis-like(6.5%). Only 4.9% of lesions could not be assigned to a sonomorphological pattern.CONCLUSION: The sonomorphological classification proposed in the present study facilitates the diagnosis,interpretation and comparison of hepatic alveolar echinococcosis in routine practice and in the context of scientific studies.
基金supported by the Natural Science Foundation of Guangdong Province under Grant No.S2013010013101the Science Foundations of Hanshan Normal University under Grant Nos.QD20131101and LZ201403
文摘This paper deals with multiobjective programming problems with support functions under （G, C, ρ）-convexity assumptions. Not only sufficient but also necessary optimality conditions for this kind of multiobjective programming problems are established from a viewpoint of （G, C, ρ）-convexity. When the sufficient conditions are utilized, the corresponding duality theorems are derived for general Mond-Weir type dual program.
基金Supported by the National Natural Science Foundation of China
文摘This paper introduces two source models: MAP(Markovian arrival process) model for the traffic with correlation and burst, e.g., voice, video, etc. and PAP(Poisson arrival process) model for the traffic with non-correlation, such as data, etc. Then a movable boundary bandwidth access policy is chosen.Basing on above model, the performance measures, e.g., mean waiting time and loss probability,especially the queue length time distribution are obtained. Finally, a number of numerical results are provided and shown through simulation.
文摘<div style="text-align:justify;"> Electric field superposition principle and Gauss’s law are the basis of electrostatics. By extended analysis on the electric field lines of a charge, it is shown that electric field superposition principle and Gauss’s law are not tenable in some states, involving the electric field of ion atmosphere that is a key concept in Debye-Hückel theory of electrolyte solution and plasma. Unveiling Debye shield, ion atmosphere (Debye spherical layer 1) actually is equivalent to continue to transmit the electric field originated from the central ion, just changing the direction of the electric field. Debye spherical layer 2 and multiple Debye spherical layers generate in the transmission. Due to the effect of the multiple Debye spherical layers of charged particles in the universe, gravitation originates from electric force. </div>
文摘Extensive excavations at the site of Ashur allowed Olaf Pedersén to reconstruct, to a considerable level of detail, the many archives and libraries in official and private collections that existed at ancient Ashur through the
文摘Internet of Things (IoT) is ubiquitous, including objects or devices communicating through heterogenous wireless networks. One of the major challenges in mobile IoT is an efficient vertical handover decision (VHD) technique between heterogenous networks for seamless connectivity with constrained resources. The conventional VHD approach is mainly based on received signal strength (RSS). The approach is inefficient for vertical handover, since it always selects the target network with the strongest signal without taking into consideration of factors such as quality of service (QoS), cost, delay, etc. In this paper, we present a hybrid approach by integrating the multi-cri- teria based VHD (MCVHD) technique and an algorithm based on fuzzy logic for efficient VHD among Wi-Fi, Radio and Satellite networks. The MCVHD provides a lightweight solution that aims to achieving seamless connectivity for mobile IoT Edge Gateway over a set of heterogeneous networks. The proposed solution is evaluated in real time using a testbed containing real IoT devices. Further, the testbed is integrated with lightweight and efficient software techniques, e.g., microservices, containers, broker, and Edge/Cloud techniques. The experimental results show that the proposed approach is suitable for an IoT environment and it outperforms the conventional RSS Quality based VHD by minimizing handover failures, unnecessary handovers, handover time and cost of service.
文摘A practical image reconstruction method for multi-source quantitative photoacoustic tomography （QPAT） is proposed in this work with the consideration of detector response function and limited-view scanning. First, the correct detector response function, i.e., spa- tim impulse response （SIR） and acousto-electric impulse response （EIR）, is considered for the ultrasonic transducer to accurately model the acoustic measurement; second, acoustic data is only measured near optical sources with meaningful signal-to-noise ratio （SNR）, i.e., the limited-view scanning, which also reduces the data acquisition time for point trans- ducer. However, due to the incomplete limited-view data, a two-step image reconstruction method （i.e., to first reconstruct initial acoustic pressure and then reconstruct optical coef- ficients） no longer applies, since it is neither possible nor necessary to robustly reconstruct initial acoustic pressure with limited-view data. Therefore, here we propose a direct image reconstruction method that incorporates SIR, EIR and limited-view scanning in a coupled opto-acoustic forward model, regularizes the framelet sparsity, and then solves the QPAT alternating direction method of multipliers. nonlinear QPAT data fidelity with tensor problem with Quasi-Newton method based
文摘现代飞行程序设计受地形、障碍物、空域和飞行性能等多种因素的影响,设计过程中需进行大量针对设计细节有效性的评估工作;设计完毕的飞行程序还需专业的飞行试飞人员进行模拟机和真机试飞,耗费大量的人力、经济成本。如果试飞前缺少针对性的分析评估,一方面会增加试飞成本的支出,另一方面也会导致真机试飞环节存在安全隐患。针对上述问题,利用深度强化学习技术,提出一种在满足飞行程序设计规范条件下,面向飞行程序有效性和可行性验证的离场航迹自动生成方法。首先,利用空气动力学原理,建立考虑飞行性能和障碍物超障因素的基本飞行动力学模型,并借助Unity3D引擎构建三维可视化的训练平台;其次,在PyTorch深度学习框架中,利用Mlagents强化学习平台构建航空器在飞行时各个阶段的试飞训练模型,设计包括起飞、转弯、巡航和降落这4个目标的场景和奖励函数。以离场飞行程序试飞为例,采用厦门高崎机场某PBN(Performance Based Navigation)离场程序进行实例训练验证,并利用动态时间规整(DTW)距离量化实际生成航迹与标称航迹之间的偏离度。实验结果显示,偏差度满足飞行程序超障保护区的限制要求。上述训练模型在其他离场程序的实验结果也验证了模型具有较好的泛化能力。
