- 标题
- 摘要
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- 实验方案
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Remote Spatio-Temporal Focusing over Multimode Fiber Enabled by Single-Ended Channel Estimation
摘要： Interest in deep probabilistic graphical models has increased in recent years, due to their state-of-the-art performance on many machine learning applications. Such models are typically trained with the stochastic gradient method, which can take a significant number of iterations to converge. Since the computational cost of gradient estimation is prohibitive even for modestly sized models, training becomes slow and practically usable models are kept small. In this paper we propose a new, largely tuning-free algorithm to address this problem. Our approach derives novel majorization bounds based on the Schatten- norm. Intriguingly, the minimizers of these bounds can be interpreted as gradient methods in a non-Euclidean space. We thus propose using a stochastic gradient method in non-Euclidean space. We both provide simple conditions under which our algorithm is guaranteed to converge, and demonstrate empirically that our algorithm leads to dramatically faster training and improved predictive ability compared to stochastic gradient descent for both directed and undirected graphical models.
关键词： Monte Carlo simulation methods,graphical models,Boltzmann distributions,Gradient methods,maximum likelihood estimation
更新于2025-09-23 15:19:57
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Numerical simulation for optimization of an ultra-thin n-type WS2/p-type c-Si heterojunction solar cells
摘要： Recently, ultra-thin tungsten disul?de (WS2) has become one of the hot spots in the research of solar cell materials due to its excellent optical and electrical properties. In this study, we use AFORS-HET software version 2.5 at air mass 1.5 to simulate the structure of n-type WS2/p-type c-Si heterojunction solar cells. Our goal is to ?nd an appropriate way to improve the performance of n-type WS2/p-type c-Si heterojunction solar cells by simulation. Through optimizing the parameters of both WS2 layer and Si layer, we obtain a maximum photovoltaic conversion e?ciency of 20.57%. Subsequently, we investigate the in?uence of the ITO work function and the interface states on the performance of n-type WS2/p-type c-Si heterojunction solar cells. It’s found that through selecting the suitable ITO work function and decreasing the interface defect density, solar cell’s performance can be further improved. Our result indicates that ultra-thin WS2 is a promising photovoltaic material for the application in solar cells.
关键词： Work function,Heterojunction solar cells,Numerical simulation,Tungsten disul?de,Interface states
更新于2025-09-23 15:19:57
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An Efficient Non-Invasive Method to Fabricate In-Fiber Microcavities Using a Continuous-Wave Laser
摘要： Natural ecosystems exhibit complex dynamics of interacting species. Man-made ecosystems exhibit similar dynamics and, in the case of mobile app stores, can be said to perform optimization as developers seek to maximize app downloads. This work aims to understand stability and instability within app store dynamics and how it affects ?tness. The investigation is carried out with AppEco, a model of the iOS App Store, which was extended for this paper and updated to model the store from 2008 to 2014. AppEco models apps containing features, developers who build the apps, users who download apps according to their preferences, and an app store that presents apps to the users. It also models developers who use commonly observed strategies to build their apps: innovator, milker, optimizer, copycat, and ?exible (the ability to choose any strategy). Results show that despite the success of the copycat strategy, there is a clear stable state for low proportion of copycats in developer populations, mirroring results in theoretical biology for producer–scrounger systems. The results also show that the best ?tness is achieved when the evolutionary optimizer (as producer) and copycat (as scrounger) strategies coexist together in stable proportions.
关键词： mobile app developers,Agent-based simulation,evolutionary ecosystem model,genetic algorithms,app stores,producer–scrounger systems,computational modeling
更新于2025-09-23 15:19:57
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Evaluation of the Impact of MZM Frequency Response on BER Performance of PAM-4 Modulated WDM-PON
摘要： Continuous growth of data tra?c in optical access networks is driving the increase of utilized data rates even up to 25 Gbit/s per wavelength. While due to utilization of signals with large electrical bandwidth, requirements on the bandwidth of electrical and electro-optical components increase signi?cantly. Addressing that, the feasibility of application of the minimal transmitter and receiver bandwidth has received considerable attention. In this research, via numerical simulation in VPI Photonics Design Suite software we evaluate the impact of the shape of MZM frequency response based on amplitude frequency response (S21) from commercial MZM speci?cation. Moreover, addressing the requirements on numerical simulation models that ensure simulation of MZM frequency response curve for prediction of the overall system performance, we have also evaluated several analytical frequency responses (corresponding to the responses of 1 and 4-pole, Bessel and Gaussian ?lters) with di?erent 3-dB bandwidth values. Based on the obtained results, we propose the approach for the simulation of MZM frequency response that is the most relevant for our utilized PAM-4 modulated WDM-PON system with 25 Gbit/s bitrate per channel.
关键词： MZM frequency response,PAM-4 modulated WDM-PON,numerical simulation,VPI Photonics Design Suite,BER performance
更新于2025-09-23 15:19:57
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ANFIS Based Voltage Determination for Photovoltaic Systems According to the Specific Cell Parameters, and a Simulation for the Non-Isolated High Gain DCa??DC Boost Converter Control Regard to Voltage Fluctuations
摘要： In this study, a solar panel is modeled and parametric simulation studies are performed with Ansys-Electronics 2019 R2 software according to atmospheric and temperature coefficient parameters that affect the efficiency of electrical energy produced in photovoltaic (PV) systems. Based on parametric simulation studies, 482 data of the voltage value of the electrical energy produced were obtained. Then a certain part of this data was used for training in Adaptive Network Fuzzy Inference System (ANFIS) algorithms and the system was tested with the estimated values produced. Thus, in the generation of solar and electrical energy, the duty ratio controller performance designed with an uninsulated DC–DC converter circuit proposed to generate a 400 V constant value DC bus voltage at the output due to voltage changes at the input is reported.
关键词： Non-Isolated High Gain converter,photovoltaic (PV) systems,parametric simulation,Adaptive Network Fuzzy Inference System (ANFIS)
更新于2025-09-23 15:19:57
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Supervised Learning of Natural-Terrain Traversability with Synthetic 3D Laser Scans
摘要： Autonomous navigation of ground vehicles on natural environments requires looking for traversable terrain continuously. This paper develops traversability classifiers for the three-dimensional (3D) point clouds acquired by the mobile robot Andabata on non-slippery solid ground. To this end, different supervised learning techniques from the Python library Scikit-learn are employed. Training and validation are performed with synthetic 3D laser scans that were labelled point by point automatically with the robotic simulator Gazebo. Good prediction results are obtained for most of the developed classifiers, which have also been tested successfully on real 3D laser scans acquired by Andabata in motion.
关键词： 3D laser scanner,field robotics,sensor simulation,traversability,supervised machine learning
更新于2025-09-23 15:19:57
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A scan-wise adaptive remeshing framework for thermal simulation of the selective laser melting process
摘要： Physics-based thermal simulation of laser powder bed fusion can greatly help understanding the process and reducing time and cost associated with experimental approaches. Numerical methods including the finite element method have been widely used to predict parts thermal-structural history during the build process. However, the simulation has scalability issues because both layer thickness and laser spot diameter are too tiny compared to the part-scale. Therefore, it is only feasible to run these simulations with massive computational resources or if the boundary conditions are simplified, which inevitably reduces the prediction accuracy. This paper proposes a tetrahedral element-based scan-wise adaptive remeshing framework for thermal simulation of the selective laser melting (SLM) process. Results show that a significant reduction of the computational time and resources can be achieved due to the reduction of the number of nodes. The proposed framework enables part-scale thermal modeling of the SLM process with detailed thermal history without sacrificing the accuracy. The effectiveness of the proposed framework is demonstrated through a large size cantilever problem.
关键词： Selective laser melting,Melt pool,Adaptive remeshing,Thermal simulation
更新于2025-09-23 15:19:57
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The Integration of Photonic Crystal Waveguides with Atom Arrays in Optical Tweezers
摘要： Integrating nanophotonics and cold atoms has drawn increasing interest in recent years due to diverse applications in quantum information science and the exploration of quantum many-body physics. For example, dispersion-engineered photonic crystal waveguides (PCWs) permit not only stable trapping and probing of ultracold neutral atoms via interactions with guided-mode light, but also the possibility to explore the physics of strong, photon-mediated interactions between atoms, as well as atom-mediated interactions between photons. While diverse theoretical opportunities involving atoms and photons in 1D and 2D nanophotonic lattices have been analyzed, a grand challenge remains the experimental integration of PCWs with ultracold atoms. Here, an advanced apparatus that overcomes several significant barriers to current experimental progress is described, with the goal of achieving strong quantum interactions of light and matter by way of single-atom tweezer arrays strongly coupled to photons in 1D and 2D PCWs. Principal technical advances relate to efficient free-space coupling of light to and from guided modes of PCWs, silicate bonding of silicon chips within small glass vacuum cells, and deterministic, mechanical delivery of single-atom tweezer arrays to the near fields of photonic crystal waveguides.
关键词： atoms and nanophotonics,quantum simulation,quantum dielectrics,quantum information science
更新于2025-09-23 15:19:57
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Self-assembled nanorods in YBCO matrix a?? a computational study of their effects on critical current anisotropy
摘要： In order to understand how the doping with self-assembled nanorods of different sizes and concentrations as well as applied magnetic fields affect the critical current anisotropy in YBa2Cu3O7?x (YBCO) thin films close to YBCO c-axis, we present an extensive and systematic computational study done by molecular dynamics simulation. the simulations are also used to understand experimentally measured Jc(θ) curves for BaHfO3, BaZrO3 and BaSnO3 doped YBCO thin films with the help of nanorod parameters obtained from transmission electron microscopy measurements. our simulations reveal that the relation between applied and matching field plays a crucial role in the formation of Jc(θ)-peak around YBCO c-axis (c-peak) due to vortex-vortex interactions. We also find how different concentrations of different size nanorods effect the shape of the c-peak and explain how different features, such as double c-peak structures, arise. In addition to this, we have quantitatively explained that, even in an ideal superconductor, the overdoping of nanorods results in decrease of the critical current. our results can be widely used to understand and predict the critical current anisotropy of YBco thin films to improve and develop new pinscapes for various transport applications.
关键词： critical current anisotropy,molecular dynamics simulation,YBCO,flux pinning,self-assembled nanorods
更新于2025-09-23 15:19:57
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Semi-Lagrangian Vlasov simulation of the interaction between femtosecond chirped and double laser pulses with a thin plasma slab
摘要： The wakefield generation and electrons acceleration in the interaction of femtosecond chirped and double laser pulses with an underdense thin plasma slab is examined by numerical solution of the relativistic Vlasov-Maxwell system of equations using the backward semi-Lagrangian method (BSL). Unlike particle-in-cell methods, the BSL method is free of numerical noise and provides an accurate representation of the distribution function, even in very low density regions of phase space where acceleration and trapping occur. The effect of density fluctuations in low density regions of phase space are important, since they affect the acceleration processes over the following interactions. Therefore, a detailed structure of the distribution function is needed to investigate this process in these regions, which only can be obtained by Vlasov codes. Excitation of wakefields by chirped, chirp free, and double pulse lasers in an underdense plasma slab are simulated using the BSL code and the results are compared. It is shown that by making use of chirped laser pulses, the mean kinetic energy of plasma electrons can be enhanced up to 40% compared with the chirp free case. The investigation of wakefield generation by double laser pulses with a time repetition equal to one plasma period, exhibits amplification of wakefield amplitude after the entrance of the second laser pulse into plasma slab.
关键词： chirped laser pulse,wakefield acceleration,thin plasma layer,semi-Lagrangian Vlasov simulation
更新于2025-09-23 15:19:57