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Articles 61831 - 61860 of 302772

Full-Text Articles in Physical Sciences and Mathematics

Seismic Attenuation, Time Delays And Raypath Bending Of Teleseisms Beneath Uturuncu Volcano, Bolivia, Alexandra K. Farrell Mar 2021

Seismic Attenuation, Time Delays And Raypath Bending Of Teleseisms Beneath Uturuncu Volcano, Bolivia, Alexandra K. Farrell

USF Tampa Graduate Theses and Dissertations

A set of 14 teleseismic earthquakes was studied to determine how wave propagation was affected by a presumed magma body beneath Uturuncu volcano, Bolivia. Teleseisms are suitable for study because they are relatively long period, contain purely P waves, and have near-vertical incidence angles. The number of events is small but the events have good signal-to-noise ratios and very similar waveforms for each event so that reliable measurements could be made of arrival times and amplitudes. Attenuation of amplitudes occurs in a NW-SE trend beneath the volcano, 14 by 34 km (long axis NW-SE). Calculated values of the quality factor …

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Building And Characterizing A Lab-Scaled Aquifer Storage And Recovery System, Murat Can Kayabas Mar 2021

Building And Characterizing A Lab-Scaled Aquifer Storage And Recovery System, Murat Can Kayabas

USF Tampa Graduate Theses and Dissertations

To use Aquifer Storage and Recovery (ASR) as a water treatment and storage method, we must understand the fate and behavior of potential contaminants in the system. Knowing more about the aquifer properties such as dispersivity will enable us to assess how the target chemicals behave in the system. Characterizing the aquifer by using a tracer is a good way to estimate dispersivity since the tracer is not adsorbed or degraded. This study aims to build a lab-scale physical model of a confined aquifer to simulate an ASR system, verify its hydraulic functionality, and characterize the hydraulics of the aquifer …

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Computational Development Of A Miniature Quantum Dot Spectrometer For Use In Space, Joseph Richardson Mar 2021

Computational Development Of A Miniature Quantum Dot Spectrometer For Use In Space, Joseph Richardson

Undergraduate Honors Theses

Miniature spectrometers are of great interest to NASA as necessary instrumentation is scaled down and optimized for specific space application. Semiconductor nanocrystals called quantum dots (QD) are being used to create a miniature high-resolution filter-based spectrometer, with the goal of use in space within 5 years. Computational imaging techniques— such as automated image analysis and mathematical spectrum reconstruction algorithms—are key to making the QD spectrometer a reality. This thesis will discuss the process of developing these computational methods, along with the improvements that have occurred from previous work.

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Efficient Hardware Constructions For Error Detection Of Post-Quantum Cryptographic Schemes, Alvaro Cintas Canto Mar 2021

Efficient Hardware Constructions For Error Detection Of Post-Quantum Cryptographic Schemes, Alvaro Cintas Canto

USF Tampa Graduate Theses and Dissertations

Quantum computers are presumed to be able to break nearly all public-key encryption algorithms used today. The National Institute of Standards and Technology (NIST) started the process of soliciting and standardizing one or more quantum computer resistant public-key cryptographic algorithms in late 2017. It is estimated that the current and last phase of the standardization process will last till 2022-2024. Among those candidates, code-based and multivariate-based cryptography are a promising solution for thwarting attacks based on quantum computers. Nevertheless, although code-based and multivariate-based cryptography, e.g., McEliece, Niederreiter, and Luov cryptosystems, have good error correction capabilities, research has shown their hardware …

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A Comparative Study Of Male And Female Undergraduate Computer Science Students’ Educational Pathways, Stephanie Fitzsimmons Mar 2021

A Comparative Study Of Male And Female Undergraduate Computer Science Students’ Educational Pathways, Stephanie Fitzsimmons

USF Tampa Graduate Theses and Dissertations

Science, Technology, Engineering and Mathematics (STEM), including Computer Science (CS) are fields that are in great demand globally. This study’s purpose was to explore the nature of the educational pathways, critical factors and commonalities/differences leading to CS undergraduate enrollment through the male and female perspectives focusing on personal/home, academic/attitude and psychological factors underlying the Social Cognitive Career Theory factors. Purposive sampling method was used for this multi-case study, comprised of CS undergraduate upperclassman. Participants shared their perspectives on their CS educational pathway via three interviews and journals. Thematic analysis of narrative for both individual and cumulative group analysis, plus researcher …

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A Gravitational-Wave Measurement Of The Hubble Constant Following The Second Observing Run Of Advanced Ligo And Virgo, Ligo Scientific Collaboration, Virgo Collaboration, Tiffany Z. Summerscales Mar 2021

A Gravitational-Wave Measurement Of The Hubble Constant Following The Second Observing Run Of Advanced Ligo And Virgo, Ligo Scientific Collaboration, Virgo Collaboration, Tiffany Z. Summerscales

Faculty Publications

This paper presents the gravitational-wave measurement of the Hubble constant (H0) using the detections from the first and second observing runs of the Advanced LIGO and Virgo detector network. The presence of the transient electromagnetic counterpart of the binary neutron star GW170817 led to the first standard-siren measurement of H0. Here we additionally use binary black hole detections in conjunction with galaxy catalogs and report a joint measurement. Our updated measurement is H0 = km s−1 Mpc−1 (68.3% of the highest density posterior interval with a flat-in-log prior) which is an improvement by a factor of …

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Common-Spectrum Process Versus Cross-Correlation For Gravitational-Wave Searches Using Pulsar Timing Arrays, Joseph D. Romano, ‪Jeffrey S. Hazboun, X. Siemens, Anne M. Archibald Mar 2021

Common-Spectrum Process Versus Cross-Correlation For Gravitational-Wave Searches Using Pulsar Timing Arrays, Joseph D. Romano, ‪Jeffrey S. Hazboun, X. Siemens, Anne M. Archibald

Physics and Astronomy Faculty Publications and Presentations

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has recently reported strong statistical evidence for a common-spectrum red-noise process for all pulsars, as seen in their 12.5-yr analysis for an isotropic stochastic gravitational-wave signal. However, there is currently very little evidence for quadrupolar spatial correlations across the pulsars in the array, which is needed to make a confident claim of detection of a stochastic gravitational-wave background. In this paper, we provide a “back-of-the-envelope” illustration of the NANOGrav 12.5-yr results for the nonexpert reader, using a very simple signal+noise model and frequentist statistics. We show that the current lack of …

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Acknowledge Of Reviewers Mar 2021

Acknowledge Of Reviewers

Journal of Sustainable Mining

No abstract provided.

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A Systematic Multiscale Investigation Of Nanoparticle-Assisted Co2 Enhanced Oil Recovery (Eor) Process For Shale Oil Reservoirs, Dayo A. Afekare Mar 2021

A Systematic Multiscale Investigation Of Nanoparticle-Assisted Co2 Enhanced Oil Recovery (Eor) Process For Shale Oil Reservoirs, Dayo A. Afekare

LSU Doctoral Dissertations

Shale oil reservoirs are prolific on the short term due to hydraulic fracturing and horizontal drilling but experience significant production decline, leading to poor ultimate recovery and leaving billions of barrels of oil buried in the ground. In this study, a systematic multi-scale investigation of an enhanced oil recovery (EOR) process using relatively inexpensive silicon dioxide nanoparticles and carbon dioxide for shale oil reservoirs was conducted. Using the Tuscaloosa Marine Shale (TMS) as a case study, aqueous dispersions of nanosilica in conjunction with CO2 were investigated at nano-to-core scales. At the nanoscale, atomic force microscope was used to investigate …

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Plant Community Response To The Combined Effects Of Elevation, And Simulated Nutrient And Sediment Loading In Sagittaria Lancifolia-Dominated Wetlands, Donnie Day Mar 2021

Plant Community Response To The Combined Effects Of Elevation, And Simulated Nutrient And Sediment Loading In Sagittaria Lancifolia-Dominated Wetlands, Donnie Day

LSU Master's Theses

Coastal wetlands are experiencing threats to their long-term sustainability brought about by the combined effects of relative sea-level rise and human modifications to hydrology, sediment delivery and nutrient loading. Restoration and management strategies can include adding sediment to the surface of deteriorating marshes to facilitate positive feedbacks among elevation, plant productivity, sediment trapping, and accretion; however, if delivered using nitrate-enriched river waters, belowground biomass and soil organic matter pools may be negatively affected, resulting in the acceleration of wetland loss. Overall, there is limited information on the combined effects of nutrient loading, sedimentation, and flooding dynamics in regulating feedbacks among …

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Accelerated Gradient Descent Methods For The Uniaxially Constrained Landau-De Gennes Model, Edison E. Chukwuemeka Mar 2021

Accelerated Gradient Descent Methods For The Uniaxially Constrained Landau-De Gennes Model, Edison E. Chukwuemeka

LSU Master's Theses

Liquid crystal models with the capability of capturing defects has been one of the main focus in modeling the behavior of such phase mathematically. A uni-axially constrained Landau-de Gennes one-constant model, which has this capability was modeled using three minimization schemes - standard gradient descent, Nesterov accelerated gradient descent, and heavy-ball accelerated gradient descent. The uni-axially constrained Landau-de Gennes energy is discretized using finite element method and the performance of the minimization schemes are measured using the classical gradient descent scheme as the baseline. The numerical experiments conducted indicated that the accelerated gradient descent schemes improved the convergence rate and …

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Relation Of Endogenous Hormone And Creeping‐Rooted Character Performance In Alfalfa, Tiemei Wang, Jingni Zhang Mar 2021

Relation Of Endogenous Hormone And Creeping‐Rooted Character Performance In Alfalfa, Tiemei Wang, Jingni Zhang

IGC Proceedings (1993-2023)

No abstract provided.

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Study On Salt Tolerance Of 9 Varieties Of Lolium Spp. In Germination And Seedling Stage, Kongchen Li Mar 2021

Study On Salt Tolerance Of 9 Varieties Of Lolium Spp. In Germination And Seedling Stage, Kongchen Li

IGC Proceedings (1993-2023)

No abstract provided.

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Technology Evolution Network Model And Simulation Based On Patent Citation Network, You Ge, Guo Hao, Liu Xiang Mar 2021

Technology Evolution Network Model And Simulation Based On Patent Citation Network, You Ge, Guo Hao, Liu Xiang

Journal of System Simulation

Abstract: On the basis of on the patent citation network and complex networks, a technology evolution network model is constrcucted, which revealed the topology structure, evolution rules and dynamics of the technology evolution network. By introducing time and fitness preferential attachments mechanism, the effect of time factor and selection law of “survival of the fittest” on evolution of network structure during the technology evolution is studied. The results showed that the technology evolution network had the characteristic of scale-free, which is the result of global selection of “survival of the fittest” in the process of technology accumulation; The effect of …

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Research On The Method Of Operational Concept Description Based On Sysml, Siming Peng, Xiao Gang, Qingzhang Yu, Zeming Li Mar 2021

Research On The Method Of Operational Concept Description Based On Sysml, Siming Peng, Xiao Gang, Qingzhang Yu, Zeming Li

Journal of System Simulation

Abstract: For the convenience of understanding and communication between researchers among different domains, the standardized method for operational concept description is preferred. Hence, based on the principles of systems architecture, the System Model Language (SysML) is proposed for the visualized and standardized description of operational concept. The form of combination for Department of Defense Architecture Framework (DoDAF) and SysML during the description of operational concept is analyzed, and the multi-view point products are used to descript the operational background, capability requirement and systems architecture as well as the operational activity of operational concept. The "Distributed Lethality" is utilized as an …

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Modeling And Analysis Of Nonstationary Gas Filtration Under Gas Dynamic Parameters Variation, N Ravshanov, Elmira Nazirova Mar 2021

Modeling And Analysis Of Nonstationary Gas Filtration Under Gas Dynamic Parameters Variation, N Ravshanov, Elmira Nazirova

Bulletin of TUIT: Management and Communication Technologies

A mathematical model that describes a partial differential equation with boundary, internal and initial conditions was developed in the article, to study the gas-dynamic parameters of the gas filtration process in a porous medium under isothermal conditions. The study was performed based on the reviews of research works related to mathematical modeling in recent years. Computational experiments (CE) were conducted on a computer to determine the response of the main parameters on the process of gas filtration in a porous medium on the basis of the developed mathematical tool (model, numerical algorithm, and software). The results of numerical calculations were …

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Comparative Study Of Energy Management Strategy Based On Value Loss Of Tram Hybrid Power System, Guo Ai, Chen Chao, Junjie Shi, Zhengjie Liu, Weirong Chen, Jiayi Liang, Liu Nan Mar 2021

Comparative Study Of Energy Management Strategy Based On Value Loss Of Tram Hybrid Power System, Guo Ai, Chen Chao, Junjie Shi, Zhengjie Liu, Weirong Chen, Jiayi Liang, Liu Nan

Journal of System Simulation

Abstract: In order to comprehensively evaluate the economy of fuel cell hybrid power system for tram and improve its durability, a value loss function based on the life of fuel cell and lithium battery in hybrid system is proposed. The demanded power in actual conditions is adopted and the value loss function is used to analyze the three energy policies including the state machine, power following, and minimum equivalent hydrogen consumption. The simulation results show that the value loss of state machine strategy is the smallest, and compared with power following and equivalent hydrogen consumption minimization strategies, this method …

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Acoustic Orbital Angular Momentum Hall Effect And Realization Using A Metasurface, Xu Dong Fan, Likun Zhang Mar 2021

Acoustic Orbital Angular Momentum Hall Effect And Realization Using A Metasurface, Xu Dong Fan, Likun Zhang

Faculty and Student Publications

Vortex beams with a twisted wavefront possess both intrinsic and extrinsic orbital angular momenta. Their coupling (viz. orbital-orbital coupling) leads to an orbital angular momentum Hall effect previously found in light, providing applications in light manipulation. Here an analogous orbital Hall effect in acoustics is reported via modeling vortex beam propagation in an inhomogeneous medium. A shift of the beam center perpendicular to the inhomogeneous direction is numerically observed to follow a path predicted by ray theory in the weak inhomogeneity approximation where the coupling and conservation of total angular momenta are identified. Experimental observation of the acoustic phenomenon with …

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Regional Integrated Energy System Model Based On Seasonal Load Difference, Songzhi Zhang Mar 2021

Regional Integrated Energy System Model Based On Seasonal Load Difference, Songzhi Zhang

Journal of System Simulation

Abstract: In order to study the coupling of electricity, heat and natural gas in the integrated regional comprehensive energy system, proposes a general energy hub model considering the load difference between winter and summer is proposed. The establishes the coupling matrix under the model is established, combined with, and combines the steady-state calculation method of natural gas network and distribution network, and develops different operation modes are developed to restrain the fluctuation of distribution network voltage and natural gas network pressure. The simulation is carried out on MATLAB/Simulink platform. The results show that the proposed model and calculation …

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Study On Navigation Simulation Method Of Crude Oil Fleet In Bridge Area, Chunhui Zhou, Hongxun Huang, Wanxia Yi, Lijia Chen, Yuanqiao Wen, Linxu Tan Mar 2021

Study On Navigation Simulation Method Of Crude Oil Fleet In Bridge Area, Chunhui Zhou, Hongxun Huang, Wanxia Yi, Lijia Chen, Yuanqiao Wen, Linxu Tan

Journal of System Simulation

Abstract: In view of the safety of over-scale fleet sailing through bridge, the water area of Wuhan Yangtze River Bridge is taken as the research area. Numerical simulation of flow field is conducted based on MIKE software to analyze the changes of water flow in different water periods and their effects on ship navigation. On this basis, according to the simulation results of the flow field, several test conditions are set up by using the Large Ship Maneuvering Simulator to carry out the simulation test of over-scale fleet sailing through the bridge. The results show that under the preset wind …

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Research On Indoor Emergency Evacuation Simulation Of Multi-Exit Based On Social Force Model, Haixiang Guo, Zeng Yang, Weiming Chen Mar 2021

Research On Indoor Emergency Evacuation Simulation Of Multi-Exit Based On Social Force Model, Haixiang Guo, Zeng Yang, Weiming Chen

Journal of System Simulation

Abstract: With the frequent occurrence of emergencies, how to evacuate dense pedestrians safely from indoor space with limited export is the key and difficult point of emergency evacuation research. Taking a university auditorium as an example to simulate through Anylogic, and the degree of consciousness is introduced to comprehensively reflect the safety education, safety training and familiarity of pedestrians and the expected speed of pedestrians in the primary social force model is improved. To solve the problem of uneven utilization of exports in multi-exit indoor, optimization plans including partition guidance and change the structure of exports are proposed. Simulation results …

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Intelligent Genetic Algorithm For Workforce Scheduling Considering Service Level In It Maintenance Service, Ruiying Chen, Chengtao Wang, Zhenyuan Liu Mar 2021

Intelligent Genetic Algorithm For Workforce Scheduling Considering Service Level In It Maintenance Service, Ruiying Chen, Chengtao Wang, Zhenyuan Liu

Journal of System Simulation

Abstract: Aiming at resolving the faults quickly and effectively with limited human resource,an IT maintenance service model with the consideration of service level is proposed, A knowledge model is proposed,a variety of mutation operators and crossover operators are designed. and the improved genetic algorithm (IGA), the intelligent genetic algorithm based on knowledge model (KIGA) and the adaptive intelligent genetic algorithm based on knowledge model (KAIGA) are formed. The results show that the adaptive mutation and crossover probability can accelerate the convergence speed of the solution, and the knowledge model can also improve the optimization effect of the solution

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The Bluff River Trail: A Community Land Ethic, Kelly F. Davis Mar 2021

The Bluff River Trail: A Community Land Ethic, Kelly F. Davis

Language, Literacy, and Sociocultural Studies ETDs

The Bluff River Trail (BRT) is a future 10+ mile trail along the San Juan River corridor in the 4-Corners region of the Southwestern United States. By asking, what is the land ethic of the Bluff Community? this qualitative study identifies behaviors and beliefs, or land ethics, between seven Bluff residents and the San Juan River corridor. A land ethic contributes to the social re/production of space; therefore, third space theory contextualizes intersecting and contradicting spatialities evidenced in data. Data collection consisted of semi-structured interviews, questionnaires and focus groups. I used a qualitative content analysis pulling from grounded theory to …

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Guaranteed Cost Preview And Repetitive Control For Uncertain Linear Discrete Time-Delay Systems, Yonghong Lan, Jinlin He Mar 2021

Guaranteed Cost Preview And Repetitive Control For Uncertain Linear Discrete Time-Delay Systems, Yonghong Lan, Jinlin He

Journal of System Simulation

Abstract: For a class of uncertain linear discrete time-delay systems, a design method for guaranteed cost preview and repetitive controller is proposed . By introducing a repetitive controller in the forward channel to improve the tracking accuracy of the system, L-order difference operators are used to construct an augmented error system that contains preview information but does not include time delay, and the design problem of guaranteed cost preview and repetitive controller is converted into an output feedback adjustment problem. Using the Lyapunov stability theory and the linear matrix inequality method, the sufficient conditions for guaranteeing the asymptotic stability of …

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Network Traffic Anomaly Detection Method For Imbalanced Data, Shuqin Dong, Bin Zhang Mar 2021

Network Traffic Anomaly Detection Method For Imbalanced Data, Shuqin Dong, Bin Zhang

Journal of System Simulation

Abstract: Aiming at the poor detection performances caused by the low feature extraction accuracy of rare traffic attacks from scarce samples, a network traffic anomaly detection method for imbalanced data is proposed. A traffic anomaly detection model is designed, in which the traffic features in different feature spaces are learned by alternating activation functions, architectures, corrupted rates and dropout rates of stacked denoising autoencoder (SDA), and the low accuracy in extracting features of rare traffic attacks in a single space is solved. A batch normalization algorithm is designed, and the Adam algorithm is adopted to train parameters of …

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Research On Generation Technology Of Computer Generated Force In Lvc Training System, Gao Ang, Zhiming Dong, Guohui Zhang, Liang Tao, Qisheng Guo Mar 2021

Research On Generation Technology Of Computer Generated Force In Lvc Training System, Gao Ang, Zhiming Dong, Guohui Zhang, Liang Tao, Qisheng Guo

Journal of System Simulation

Abstract: LVC training system of the combat equipment under the condition of confrontation is an effective means of training, aiming at the problem that in LVC training system, computer generated forces are difficult to meet the demand of training problems. The concept of LVC training and LVC training system is clarified, according to the relationship between model and system structure, the corresponding modeling technology requirements of three different hierarchical models, namely logical range entity configuration, command entity and combat entity, are expounded. According to the specific requirements, four computer-generated force generation methods are proposed, namely, logical target range virtual and …

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Recognizing Emotion In The Wild Using Multimodal Data, Shivam Srivastava Mar 2021

Recognizing Emotion In The Wild Using Multimodal Data, Shivam Srivastava

USF Tampa Graduate Theses and Dissertations

In this work, I will present our approach of using multi-modal data for recognizing human emotion and behavior in the wild. The study is divided into four tasks: group emotion recognition, driver gaze prediction, student engagement prediction, and emotion recognition using physiological signals. We explore multiple approaches including classical machine learning tools such as random forests, state-of-the-art deep neural networks, and multiple fusion and ensemble-based approaches. We also show that similar approaches can be used across tracks as many of the features generalize well to the different problems (e.g. facial features).

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Strategies In Botnet Detection And Privacy Preserving Machine Learning, Di Zhuang Mar 2021

Strategies In Botnet Detection And Privacy Preserving Machine Learning, Di Zhuang

USF Tampa Graduate Theses and Dissertations

Peer-to-peer (P2P) botnets have become one of the major threats in network security for serving as the infrastructure that responsible for various of cyber-crimes. Though a few existing work claimed to detect traditional botnets effectively, the problem of detecting P2P botnets involves more challenges. In this dissertation, we present two P2P botnet detection systems, PeerHunter and Enhanced PeerHunter. PeerHunter starts from a P2P hosts detection component. Then, it uses mutual contacts as the main feature to cluster bots into communities. Finally, it uses community behavior analysis to detect potential botnet communities and further identify bot candidates. Enhanced PeerHunter is an …

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Simulation Platform For Source-Load Control Of Active Power Based On Modular Architecture, Hu Yang, Wenying Liu, Liping Zhu, Li Xiao, Weizhou Wang Mar 2021

Simulation Platform For Source-Load Control Of Active Power Based On Modular Architecture, Hu Yang, Wenying Liu, Liping Zhu, Li Xiao, Weizhou Wang

Journal of System Simulation

Abstract: The integrated proportion of wind power is increasing year by year, and the source-load coordinated control of active power can effectively improve the level of wind power consumption. In order to ensure the effective application of the strategy, a simulation platform based on modular architecture is developed for source-load control of active power, including SQL Server database, timing control module of data interaction, calculation module of source-load control strategy, and output display module. The simulation platform solves the automatic control of data interaction timing in the process of source-load control, and visualizes the effect of the source-load control, so …

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Path Designing Of Multi-Omnidirectional Wheel Collaborative Sorting Platform, Li Qi, Wang Wei Mar 2021

Path Designing Of Multi-Omnidirectional Wheel Collaborative Sorting Platform, Li Qi, Wang Wei

Journal of System Simulation

Abstract: Aiming at the problems of low efficiency, high labor cost and low flexibility of traditional logistics sorting system, an automatic logistics sorting system is designed. The improved A* algorithm and the artificial potential field method are used to realize the automatic path planning of the system by taking the transportation path as the research object. The A* algorithm is improved by adjusting the weights of actual cost and estimated cost, and the artificial potential field method is improved by adding virtual sub-target points and adjusting adaptive parameters, so as to complete the function of path planning of goods. Simulation …

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