Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 15481 - 15510 of 302428

Full-Text Articles in Physical Sciences and Mathematics

Research On Unmanned Swarm Combat System Adaptive Evolution Model Simulation, Zhiqiang Li, Yuanlong Li, Laixiang Yin, Xiangping Ma Apr 2023

Research On Unmanned Swarm Combat System Adaptive Evolution Model Simulation, Zhiqiang Li, Yuanlong Li, Laixiang Yin, Xiangping Ma

Journal of System Simulation

Abstract: Aiming at the fact that the intelligent unmanned swarm combat system is mainly composed of large-scale combat individuals with limited behavioral capabilities and has limited ability to adapt to the changes of battlefield environment and combat opponents, a learning evolution method combining genetic algorithm and reinforcement learning is proposed to construct an individual-based unmanned bee colony combat system evolution model. To improve the adaptive evolution efficiency of bee colony combat system, an improved genetic algorithm is proposed to improve the learning and evolution speed of bee colony individuals by using individual-specific mutation optimization strategy. Simulation experiment on …


Research Progress Of Opponent Modeling Based On Deep Reinforcement Learning, Haotian Xu, Long Qin, Junjie Zeng, Yue Hu, Qi Zhang Apr 2023

Research Progress Of Opponent Modeling Based On Deep Reinforcement Learning, Haotian Xu, Long Qin, Junjie Zeng, Yue Hu, Qi Zhang

Journal of System Simulation

Abstract: Deep reinforcement learning is an agent modeling method with both deep learning feature extraction ability and reinforcement learning sequence decision-making ability, which can make up for the depleted non-stationary adaptation, complex feature selection and insufficient state-space representation ability of traditional opponent modeling. The deep reinforcement learning-based opponent modeling methods are divided into two categories, explicit modeling and implicit modeling, and the corresponding theories, models, algorithms and applicable scenarios are sorted out according to the categories. The applications of deep reinforcement learning-based opponent modeling techniques on different fields are introduced. The key problems and future development are summarized to provide …


Predicting Groundwater Spring Locations From Topographic And Climatic Data Using Maxent Modeling, Ayten Ece Koc Apr 2023

Predicting Groundwater Spring Locations From Topographic And Climatic Data Using Maxent Modeling, Ayten Ece Koc

USF Tampa Graduate Theses and Dissertations

The World Resources Institute reveals that 17 countries face extremely high levels of water stress. Moreover, with increasing population and industrialization, the gap between water supply and demand increases day by day around the world. Groundwater is a key freshwater source, and springs are important resources as they enable to access groundwater. Therefore, it is crucial to monitor, protect, and manage groundwater springs. The first step in spring management is to recognize and define freshwater resources and to determine the locations of groundwater springs that serve as natural discharge points. Traditionally, field studies have been employed to determine the locations …


Deficit Irrigation Management For Irrigated Corn In Nebraska: Economically Viable?, Lia Nogueira, Cory Walters, Emily O'Donnell, Wesley Peterson, Suat Irmak Apr 2023

Deficit Irrigation Management For Irrigated Corn In Nebraska: Economically Viable?, Lia Nogueira, Cory Walters, Emily O'Donnell, Wesley Peterson, Suat Irmak

Cornhusker Economics

In this study we determine the economic value of deficit irrigation management using both technological and methodological advancements. The use of soil moisture probes represents the technological improvement. We provide improvements in the methodology as follows. Regarding data, we employ a field-size study, instead of plots, where the irrigation decision is determined by the moisture level in the soil measured through a soil moisture probe. Regarding the understanding of the yield response to water, although we examine the commonly used quadratic function, we improve upon this specification by also examining an alternative response function, the linear response stochastic plateau. Our …


Trajectory Control Of Crawler Robot Based On Lstm And Smc, Dongyang Liu, Wenwen Zha, Liang Tao, Cheng Zhu, Lichuan Gu, Jun Jiao Apr 2023

Trajectory Control Of Crawler Robot Based On Lstm And Smc, Dongyang Liu, Wenwen Zha, Liang Tao, Cheng Zhu, Lichuan Gu, Jun Jiao

Journal of System Simulation

Abstract: Trajectory tracking is an important part of mobile robot control technology and possesses prospect. Highly nonlinear dynamic characteristics are the main obstacles of controller design. A SMC method based on LSTM and quasi-sliding mode is proposed. The kinematics model and dynamics model of the tracked vehicle are given, and the sliding mode control system is established based on the dynamics model. LSTM network based on deep learning method is designed to control and compensate the unknown interference items, reduce the influence of external interference, and reduce the tremor phenomenon by combining the advantages of LSTM network and quasi-sliding …


Dynamics Modeling And Online Prediction Of Energy Consumption Of Discrete Manufacturing System, Wei Chen, Yan Wang, Zhicheng Ji Apr 2023

Dynamics Modeling And Online Prediction Of Energy Consumption Of Discrete Manufacturing System, Wei Chen, Yan Wang, Zhicheng Ji

Journal of System Simulation

Abstract: Aiming at the traditional energy consumption modeling methods of discrete manufacturing system being difficult to adapt to the complexity and variability of working conditions, an online dynamic energy consumption modeling method based on real-time data is proposed. The energy consumption affecting factors are determined by analyzing the operation mechanism of the discrete manufacturing system and equipment. An online sequential extreme learning machine algorithm that can dynamically adjust the number of hidden layer nodes is proposed to construct the energy consumption model. The real-time data can update the model quickly. Bernstein's inequality is introduced to improve the model data screening …


Knowledge Graph-Based Process Knowledge Reasoning Method For Intelligent Production System, Weikai Yang, Yan Wang, Zhicheng Ji Apr 2023

Knowledge Graph-Based Process Knowledge Reasoning Method For Intelligent Production System, Weikai Yang, Yan Wang, Zhicheng Ji

Journal of System Simulation

Abstract: Aiming at the disadvantages of high redundancy and weakness between knowledge and data in intelligent production system, and the difficulty to perform knowledge reasoning, a process knowledge reasoning method for knowledge maps is proposed. The input information is semantically labeled and classified, the characteristics of the information match are extracted, the extracted local feature and global feature are associated through graph convolution method, and the feature of the difference value information is integrated and mapped with the constructed knowledge graph. Different reasoning rules are used according to different reasoning types, and the association and topology information between instances are …


Multi-Agent Cooperative Combat Simulation In Naval Battlefield With Reinforcement Learning, Ding Shi, Xuefeng Yan, Lina Gong, Jingxuan Zhang, Donghai Guan, Mingqiang Wei Apr 2023

Multi-Agent Cooperative Combat Simulation In Naval Battlefield With Reinforcement Learning, Ding Shi, Xuefeng Yan, Lina Gong, Jingxuan Zhang, Donghai Guan, Mingqiang Wei

Journal of System Simulation

Abstract: Due to the rapidly-changed situations of future naval battlefields, it is urgent to realize the high-quality combat simulation in naval battlefields based on artificial intelligence to comprehensively optimize and improve the combat effectiveness of our army and defeat the enemy. The collaboration of combat units is the key point and how to realize the balanced decision-making among multiple agents is the first task. Based on decoupling priority experience replay mechanism and attention mechanism, a multi-agent reinforcement learning-based cooperative combat simulation (MARL-CCSA) network is proposed. Based on the expert experience, a multi-scale reward function is designed, on which a naval …


Voltage And Reactive Power Combinational Evaluation Of Regional Power Grid Based On Ewm-Ahp-Bp Neural Network, Yuqi Ji, Huan Xie, Shaoyu Shi, Ping He, Nan Jin, Huili Wang Apr 2023

Voltage And Reactive Power Combinational Evaluation Of Regional Power Grid Based On Ewm-Ahp-Bp Neural Network, Yuqi Ji, Huan Xie, Shaoyu Shi, Ping He, Nan Jin, Huili Wang

Journal of System Simulation

Abstract: In order to quantitatively evaluate the influence of renewable energy access on voltage and reactive power operation, a combinational evaluation method of voltage and reactive power based on EWM-AHP-BP neural network is proposed to carry out the multi-objective evaluation weight calculation. Considering voltage qualified rate, voltage fluctuation, power factor qualified rate and reactive power reserve, the comprehensive evaluation model is established. The operation data of renewable energy and power load are clustered to divide the typical scenarios and the evaluation model under multiple scenarios is scored by the combination method of entropy weight method and analytic hierarchy process. The …


Research On Workshop Logic Modeling And Simulation Based On Finite State Machine, Mingyuan Liu, Jiaxiang Xie, Hao Wu, Jianlin Fu, Guofu Ding Apr 2023

Research On Workshop Logic Modeling And Simulation Based On Finite State Machine, Mingyuan Liu, Jiaxiang Xie, Hao Wu, Jianlin Fu, Guofu Ding

Journal of System Simulation

Abstract: Discrete manufacturing is common in aircraft, ships, electronic equipment, automobile and other manufacturing industries. To ensure the correctness and flexibility of the modeling and simulation process of discrete manufacturing workshops, a logical modeling and simulation method for the production process of discrete manufacturing workshop is proposed. Based on the theory of discrete event dynamic systems and finite-state machines, the attributes and behaviors of the key elements of the discrete manufacturing workshop are abstracted into a unified logic model, and the function of various elements are realized through inheritance. A production process simulation algorithm is designed for the unified model …


Construction Technology Of Hand Posture Dataset Based On Virtual Simulation Method, Jiaxin Chen, Guohui Zhou, Jianbai Yang Apr 2023

Construction Technology Of Hand Posture Dataset Based On Virtual Simulation Method, Jiaxin Chen, Guohui Zhou, Jianbai Yang

Journal of System Simulation

Abstract: Hand posture is an important carrier of human-computer interaction, and the acquisition and recognition of posture information largely depends on the hand posture dataset. Existing datasets can be divided into two categories, real datasets and synthetic datasets. As real data is limited by equipment, environment, and other factors, the classification of hand posture is insufficient and the annotation is mixed with a lot of manual errors. The existing synthetic data can solve the data scale problem of real data, but the synthetic hand posture volume is limited and with some unreasonable kinematic postures of which the data form are …


Cyber Security In Cyber Space, James D. Lee Jr. Apr 2023

Cyber Security In Cyber Space, James D. Lee Jr.

Cybersecurity Undergraduate Research Showcase

For almost twenty years, the Internet has been a driving force in global communication and an integral part of people's everyday lives. As a result of technical developments and declining prices, over 3 billion people worldwide now utilize the Internet. The Internet has created a global infrastructure, and it is worth billions of dollars annually to the global economy (Judge et al.). Today's economic, commercial, cultural, social, and governmental activities and exchanges occur in Cyberspace, involving individuals, enterprises, non-profit organizations, and government and governmental agencies (Aghajani and Ghadimi 220). Cyberspace is the birthplace of much of the world's most essential …


Carbonate Microfacies Of The Middle To Upper Pennsylvanian Cache Creek Group At Meadow Lake, British Columbia, Canada, Brennen Leidy Apr 2023

Carbonate Microfacies Of The Middle To Upper Pennsylvanian Cache Creek Group At Meadow Lake, British Columbia, Canada, Brennen Leidy

Undergraduate Research Conference

No abstract provided.


Functional Fluorescent Silver Nanoclusters On Single Stranded Dna Scaffolds, Ravyn Solis, Angel Torres, Brock Gascon Apr 2023

Functional Fluorescent Silver Nanoclusters On Single Stranded Dna Scaffolds, Ravyn Solis, Angel Torres, Brock Gascon

Undergraduate Research Conference

The aim of the present study is to determine the effectiveness of silver nanocluster (Ag NC) against biofilm of Bacillus Thuringiensis ( and Pseudomonas Aeruginosa ( A 60 base long DNA aptamer specific for BT tied to the 5 end of a 16 base cytosine rich DNA oligonucleotide is chosen as the template for growing the Ag NC Two DNA aptamers specific for PA and part of their sequences were chosen as templates for growing the Ag NC Circular dichroism ( studies determined the presence of secondary structures In addition, UV/Vis absorption and fluorescence spectroscopic studies confirmed the formation of …


Effectiveness Of Sansevieria Plants To Purify The Vocs In Air Caused By The Use Of Febreeze And Diffuser Contaminants, Garrett Hacker, Quinn Whidden, Alayna Wagner, Zach Palmer, Brystal Beyer Apr 2023

Effectiveness Of Sansevieria Plants To Purify The Vocs In Air Caused By The Use Of Febreeze And Diffuser Contaminants, Garrett Hacker, Quinn Whidden, Alayna Wagner, Zach Palmer, Brystal Beyer

Undergraduate Research Conference

Volatile organic compounds (VOCs) are a danger to every household that has access to chemical products such as air fresheners or select cleaning products. VOCs are dangerous when people are around high concentrations for any extended period. This experiment was conducted to examine the ability of sansevieria plants to filter VOCs added from normal household products. The plants used in this experiment were propagated into smaller pieces in order to fit into capsules. To begin testing, the contaminants were added to the capsules and the VOC levels were measured overtime with the Ion Science Tiger sensor. The basic trend of …


Determination Of The Cation Exchange Capacity In Smectite Clays, Allison Swaim Apr 2023

Determination Of The Cation Exchange Capacity In Smectite Clays, Allison Swaim

Undergraduate Research Conference

No abstract provided.


Air Pollutants Around An Animal Feed Processing Facility In Nacogdoches, Tx: A Study On Their Effect On Local Outdoor Air Quality, Reyna Burns, Remigio Casanova, Cari Mitchell, Caroline Moore, Kaylee Zirlott Apr 2023

Air Pollutants Around An Animal Feed Processing Facility In Nacogdoches, Tx: A Study On Their Effect On Local Outdoor Air Quality, Reyna Burns, Remigio Casanova, Cari Mitchell, Caroline Moore, Kaylee Zirlott

Undergraduate Research Conference

In this exploratory study, different odorous compounds were measured near TFP Nutrition to better understand the impact of odor on local outdoor air quality. TFP Nutrition produces pet feed, livestock feed, and agricultural fertilizer for local brand Lone Star Feeds. It is known in the Nacogdoches area for producing powerful odors near its facilities. It is in the downtown area of the city and in proximity to an elementary school, recreational softball fields, and residential homes. Odors can be connected to the presence of air pollutants. This study on air quality was performed to quantify this data on odors for …


Computer Modelling Of The Interaction Between Cerme-8 J Domain And Cehsp70-1, Grace Thornhill, Cole Easley Apr 2023

Computer Modelling Of The Interaction Between Cerme-8 J Domain And Cehsp70-1, Grace Thornhill, Cole Easley

Undergraduate Research Conference

Abstract: Rme-81 is a J domain-containing plasma membrane protein that is required for endocytosis in various cells2. The J domain is a characteristic structural motif found mainly in heat shock protein 40 (Hsp40 or DnaJ) and other proteins such as Rme-83. Within the J domain is a tripeptide, the HPD motif, that is required by the J-domain protein to interact with and stimulate the ATPase activity of Hsp70, a major cellular chaperone4. The Rme-8 protein in C. elegans, CeRme-8, has not been identified with a particular Hsp70 partner. CeHsp70-1 is the only cytosolic Hsp70 in C. elegans, therefore, we hypothesize …


Detection Of Carbamazepine, Diclofenac, And Ketoprofen Via A Spe-Hplc-Pda Method In A Municipal Wastewater Treatment Plant In East Texas, Usa, Gary Lopez, Anthony Broom Apr 2023

Detection Of Carbamazepine, Diclofenac, And Ketoprofen Via A Spe-Hplc-Pda Method In A Municipal Wastewater Treatment Plant In East Texas, Usa, Gary Lopez, Anthony Broom

Undergraduate Research Conference

Pharmaceutical compounds are introduced into the environment and may pose adverse environmental and human health effects. The sources of pharmaceuticals include sewage, animal waste, and/or improper disposal from homes and hospitals. In this study, the spectroscopic, and chromatographic properties of carbamazepine (CBZ), diclofenac (DF), and ketoprofen (KT) were analyzed by using UV-Vis, fluorescence and HPLC. Via UV-VIS spectroscopy, CBZ, DF, and KT exhibited absorption peaks at 285 nm, 284 nm and 255.6 nm, respectively. The determined fluorescence quantum yield (Ff) for CBZ, DF, and KT were Ff = 0.226, 0.287, and 0.327, respectively. Retention times was observed at 3.84 (CBZ), …


Beer We Go! A Study Of Carbonated And Nitrogenated Beers, Sadie Atkins, Holly S. Gibson Apr 2023

Beer We Go! A Study Of Carbonated And Nitrogenated Beers, Sadie Atkins, Holly S. Gibson

Undergraduate Research Conference

A flavorful crisp beer is a popular, worldwide beverage. Beer can be either carbonated or nitrogenated, each giving a different sensory outcome. Carbonated beer, such as Budweiser, has a crispy and light texture, whereas nitrogenated beer, such as Guinness, has a creamy, smooth mouthfeel. A comparison study of these two different beer types was done using a Packaged Beverage Analyzer (PBA). The PBA is used to analyze the density, CO CO2, O 2, N 2, and alcohol content of various beverages, such as beer, sparkling water, and soda. The parameters assigned to the carbonated beer were container type and temperature …


Over-Determined Control Systems On Time Scales, Danian Castillo, Drew Barnes, Nick Wintz Apr 2023

Over-Determined Control Systems On Time Scales, Danian Castillo, Drew Barnes, Nick Wintz

2023 Student Academic Showcase

Control theory is a branch of mathematics focused on observing or controlling a process governed by a dynamic equation. We use state-space notation to represent all meaningful information about our process. This means our processes are expressed in vector form. Typically, the state matrix is square. In this project, we consider a control system where the corresponding state is over-determined, meaning there are more rows than columns. In addition, our state equation is on a time scale T, which allows us to consider discrete, continuous, or hybrid measurements. Here, we offer two methods to solve the dynamic system. Finally, we …


Telescope Restoration, Aidan Tueller Apr 2023

Telescope Restoration, Aidan Tueller

Student Research Symposium

In partnership with Dr. Jan Sojka, head of the Physics Department, a plan was created to make the telescope on top of the Engineering Lab building operational again for either staff, students, classes, or labs to use. The telescope was purchased through funds by Utah NASA Space Grant Consortium. This presentation will give a recap of how the restoration went and plans for future use of the telescope.


Identifying Overwash Layers In Marsh Sediment, Charles Mina Apr 2023

Identifying Overwash Layers In Marsh Sediment, Charles Mina

Undergraduate Research Competition

Hurricanes have become one of the most researched topics in recent years, due to their damage costs and their uncertain correlations with climate change. Much of the research for this topic has come from direct interaction with storms, such as damage reports and land surveys. However, there is a gap in the historical record of hurricanes, as most historical record is only written. These records can be biased and are too short of a record to identify a pattern of climate change. Grain size analysis, where sizes of sediment grains are measured, can be used to identify the storm events …


Comparative Analysis Of Implementing Solar Energy In South Carolina, Paige Huntzberry, Jo Whitney Apr 2023

Comparative Analysis Of Implementing Solar Energy In South Carolina, Paige Huntzberry, Jo Whitney

Undergraduate Research Competition

Solar energy is becoming an increasingly popular method of providing energy to homes and businesses all over the world. Converting to solar energy is a huge step in reducing our carbon footprint, a driving force of global climate change. While this type of energy production provides an eco-friendly approach to power, requiring minimal maintenance and virtually no additional infrastructure, many are still opposed to the implementation due to financial reservations. The aim of this project is to design a solar array for installation on a building at the Medical University of South Carolina, providing a cost effective and practical approach …


The Impact Of Prc Language Policies On Minority Languages Of China, Margaret Shoop Apr 2023

The Impact Of Prc Language Policies On Minority Languages Of China, Margaret Shoop

Undergraduate Research Competition

While language is often used as a tool to bring people together and celebrate differences, language can also be weaponized and used to suppress minority groups of people. There are over three hundred unique languages and dialects spoken in Mainland China, with Mandarin Chinese being the most widely spoken of the languages. Mandarin is the official state language of the People’s Republic of China (PRC), and it is also the primary language taught in schools across the country. Despite official Chinese policy of teaching Mandarin Chinese alongside local dialects, Mandarin is favored over minority languages. The unequal emphasis on Mandarin …


Seasonal Fluctuation Of Nutrients That Lead To Microcystis Bloom Development In Wall Pond, Coastal Carolina University, Alyssa Antolak Apr 2023

Seasonal Fluctuation Of Nutrients That Lead To Microcystis Bloom Development In Wall Pond, Coastal Carolina University, Alyssa Antolak

Undergraduate Research Competition

The harmful cyanobacteria Microcystis globally dominates eutrophic freshwater systems. Eutrophication leading to nitrogen and phosphorus loading into aquatic systems is increasing bloom propagation and shifting diatom/dinoflagellate dominated systems to cyanobacteria dominated systems. Understanding seasonal variability and environmental parameters combined with nutrient loading will allow for better understanding of what factors are influencing Microcystis blooms. Biweekly plankton samples, environmental parameters, and nutrients were collected from Wall Pond from spring 2022-spring 2023. Nitrogen and phosphate limitation was examined by performing seasonal nutrient limitation experiments. Early results show that yearly plankton samples shifted from diatom dominated in the late summer-early fall to Microcystis …


"Challenging The Known." 16th Annual Research Week: Event Proceedings, University Of The Incarnate Word Apr 2023

"Challenging The Known." 16th Annual Research Week: Event Proceedings, University Of The Incarnate Word

Research Week Archived Proceedings

Presentations of completed and ongoing research activity conducted by graduate students, undergraduate students, and faculty at University of the Incarnate Word. Includes poster, podium, visual arts, interactive demo, and creative and performing arts presentations. Coordinated and presented by the Office of Research and Graduate Studies.


Fast Computation Of Friction Stir Welding Process With Model Order Reduction And Machine Learning, Joshua Kay Apr 2023

Fast Computation Of Friction Stir Welding Process With Model Order Reduction And Machine Learning, Joshua Kay

Student Research Symposium

Joining aluminum alloys and other metal workpieces is a typical manufacturing process, which can be accomplished by various welding techniques. Friction stir welding (FSW), a relatively new technology patented in 1991, has many advantages over conventional welding processes. For the FSW process, it is desirable to determine an optimal set of parameters to avoid product defects in the joints. Modeling and simulating the FSW process is computationally expensive which creates a bottleneck in searching for optimal operating parameters. Reduced order modeling techniques will be used to significantly reduce computation time for FSW models while maintaining accuracy. In addition, machine learning …


Spot-Fire Distance Increases Disproportionately For Wildfires Compared To Prescribed Fires As Grasslands Transition To Juniperus Woodlands, Victoria M. Donovan, Dillon T. Fogarty, Dirac L. Twidwell Jr Apr 2023

Spot-Fire Distance Increases Disproportionately For Wildfires Compared To Prescribed Fires As Grasslands Transition To Juniperus Woodlands, Victoria M. Donovan, Dillon T. Fogarty, Dirac L. Twidwell Jr

School of Natural Resources: Faculty Publications

Woody encroachment is one of the greatest threats to grasslands globally, depleting a suite of ecosystem services, including forage production and grassland biodiversity. Recent evidence also suggests that woody encroachment increases wildfire danger, particularly in the Great Plains of North America, where highly volatile Juniperus spp. convert grasslands to an alternative woodland state. Spot-fire distances are a critical component of wildfire danger, describing the distance over which embers from one fire can cause a new fire ignition, potentially far away from fire suppression personnel. We assess changes in spot-fire distances as grasslands experience Juniperus encroachment to an alternative woodland state …


Exploring The Association Of Brownfield Remediation Status With Socioeconomic Conditions In Wayne County, Mi, Brendan F. O'Leary, Alex B. Hill, Colleen Linn, Mei Lu, Carol J. Miller, Andrew Newman, F. Gianluca Sperone, Qiong Zhang Apr 2023

Exploring The Association Of Brownfield Remediation Status With Socioeconomic Conditions In Wayne County, Mi, Brendan F. O'Leary, Alex B. Hill, Colleen Linn, Mei Lu, Carol J. Miller, Andrew Newman, F. Gianluca Sperone, Qiong Zhang

Urban Studies and Planning Faculty Research Publications

Urban neighborhoods with locations of environmental contamination, known as brownfields, impact entire neighborhoods, but corrective environmental remedial action on brownfields is often tracked on an individual property basis, neglecting the larger neighborhood-level impact. This study addresses this impact by examining spatial differences between brownfields with unmitigated environmental concerns (open site) and sites that are considered fully mitigated or closed in urban neighborhoods (closed site) on the US census tract scale in Wayne County, MI. Michigan’s Department of Environment, Great Lakes, and Energy’s leaking underground storage tank (LUST) database provided brownfield information for Wayne County. Local indicators of spatial association (LISA) …