F. Antonio Medrano | Texas A&M University - Corpus Christi (original) (raw)
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Papers by F. Antonio Medrano
Academia letters, Mar 22, 2022
The corridor location problem for determining good route alternatives for developing new infrastr... more The corridor location problem for determining good route alternatives for developing new infrastructure often requires generating many viable alternatives which may be later evaluated in public discourse. One method for generating large sets of least cost paths is by solving the kshortest path problem on a terrain network, but its usage in the literature on finding route alternatives has been limited to routing over sparse road or communication networks. We explored the use of k-shortest path techniques on the denser graph structures of GIS terrain data to examine if they are an efficient approach for corridor location problems. We found that the exponential nature of the k-shortest path problem makes this an overwhelming approach, both in terms of memory and computation time. Future work should focus on finding smart methods of reducing the problem size while retaining optimal solutions, as well as modifying the algorithms to run on high performance supercomputers in order to solve...
EURO Journal on Computational Optimization, 2020
The vertex p-center problem consists of locating p facilities among a set of M potential sites su... more The vertex p-center problem consists of locating p facilities among a set of M potential sites such that the maximum distance from any demand to its closest located facility is minimized. The complete vertex p-center problem solves the p-center problem for all p from 1 to the total number of sites, resulting in a multi-objective tradeoff curve between the number of facilities and the service distance required to achieve full coverage. This trade-off provides a reference to planners and decision-makers, enabling them to easily visualize the consequences of choosing different coverage design criteria for the given spatial configuration of the problem. We present two fast algorithms for solving the complete p-center problem, one using the classical formulation but trimming variables while still maintaining optimality, the other converting the problem to a location set covering problem and solving for all distances in the distance matrix. We also discuss scenarios where it makes sense to solve the problem via brute-force enumeration. All methods result in significant speed-ups, with the set covering method reducing computation times by many orders of magnitude.
Academia Letters, 2022
Blockchain technology has a decentralized and distributed structure enabling secure and transpare... more Blockchain technology has a decentralized and distributed structure enabling secure and transparent transactions. This technology is no longer just speculation but over the past few years has moved on to a wide range of real-world applications in finance, energy, security, and identity management. Researchers are enthusiastic about the use of its features such as decentralized storage and authentication in the healthcare industry, particularly for data management and access. Considering the different types of blockchain frameworks available (Private, Public), a private blockchain instance requiring all participants to be known would be ideal in the case of medical records. A permissioned Hyperledger such as the one implemented in Swiss hospitals to fight medical counterfeit scandals [1] is studied in case studies concerning Blockchain for health care management [2][4] support the general researcher consensus that Blockchain is indeed a great candidate for healthcare record management over traditional DBMS. A blockchain deployment would effectively enable the creation of a single means for record creation and storage. Not to mention the fact that inherent blockchain characteristics effectively meet all of the demands that the modern healthcare industry requires in terms of data storage-Security, Interoperability, Data sharing, and access.[3] This work describes the creation of a blockchain-based patient health record creation and retrieval framework 1 that will overhaul current systems in place at the same time meeting standards put in place for ensuring health data security and integrity.
pNISE is a parallelized NISE algorithm applied toward biobjective shortest path analysis on raste... more pNISE is a parallelized NISE algorithm applied toward biobjective shortest path analysis on raster grids used in Medrano & Church (2015). Serial NISE was originally published in Cohon <em>et al.</em> (1979) This is the first release intended to enable public archiving. The repository is publicly accessible at https://github.com/antoniomedrano/pNISE
This report summarizes a two-day expert meeting on “Spatial Discovery,” organized jointly by the ... more This report summarizes a two-day expert meeting on “Spatial Discovery,” organized jointly by the Library and the Center for Spatial Studies of the University of California, Santa Barbara (UCSB), and held on June 16–17, 2015 at the Upham Hotel, in Santa Barbara. The 24 participants contributed expertise in Library Science, as well as knowledge pertaining to spatial information and relevant research on data-seeking behavior. Five keynote addresses as well as several plenary and break-out discussions explored the challenges, best practices, and potential strategies associated with the cross-platform discovery of spatial data in the context of modern libraries.
Spatial analysis extracts meaning and insights from spatially referenced data, where the results ... more Spatial analysis extracts meaning and insights from spatially referenced data, where the results are highly dependent on the quality of the data used and the manipulations on the data when preparing it for analysis. Users should understand the impacts that data representations may have on their results in order to prevent distortions in their outcomes. We study the consequences of two common data preparations when locating a linear feature performing shortest path analysis on raster terrain data: 1) the connectivity of the network generated by connecting raster cells to their neighbors, and 2) the range of the attribute scale for assigning costs. Such analysis is commonly used to locate transmission lines, where the results could have major implications on project cost and its environmental impact. Experiments in solving biobjective shortest paths show that results are highly dependent on the parameters of the data representations, with exceedingly variable results based on the choi...
Geographic Information Science & Technology Body of Knowledge
Transactions in GIS, 2016
Academic libraries have always supported research across disciplines by integrating access to div... more Academic libraries have always supported research across disciplines by integrating access to diverse contents and resources. They now have the opportunity to reinvent their role in facilitating interdisciplinary work by offering researchers new ways of sharing, curating, discovering, and linking research data. Spatial data and metadata support this process because location often integrates disciplinary perspectives, enabling researchers to make their own research data more discoverable, to discover data of other researchers, and to integrate data from multiple sources. The Center for Spatial Studies at the University of California, Santa Barbara (UCSB) and the UCSB Library are undertaking joint research to better enable the discovery of research data and publications. The research addresses the question of how to spatially enable data discovery in a setting that allows for mapping and analysis in a GIS while connecting the data to publications about them. It suggests a framework for an integrated data discovery mechanism and shows how publications may be linked to associated data sets exposed either directly or through metadata on Esri's Open Data platform. The results demonstrate a simple form of linking data to publications through spatially referenced metadata and persistent identifiers. This linking adds value to research products and increases their discoverability across disciplinary boundaries.
Journal of Multi-Criteria Decision Analysis, 2015
Modern Accelerator Technologies for Geographic Information Science, 2013
Journal of Geographical Systems, 2014
ABSTRACT The problem of corridor location can be found in a number of fields including power tran... more ABSTRACT The problem of corridor location can be found in a number of fields including power transmission, highways, and pipelines. It involves the placement of a corridor or rights-of-way that traverses a landscape starting at an origin and ending at a destination. Since most systems are subject to environmental review, it is important to generate competitive, but different alternatives. This paper addresses the problem of generating efficient, spatially different alternatives to the corridor location problem. We discuss the weaknesses in current models and propose a new approach which is designed to overcome many of these problems. We present an application of this model to a real landscape and compare the results to past work. Overall, the new model called the multi-gateway shortest path problem can generate a wide variety of efficient alignments, which eclipse what could be generated by past work.
International Regional Science Review, 2014
Corridor location for developing new infrastructure such as transmission lines, roadways, and pip... more Corridor location for developing new infrastructure such as transmission lines, roadways, and pipelines over terrain must consider numerous factors when determining the set of optimal route candidates. Previous researchers have cast this problem as a multiobjective least cost path problem, where competing objectives represent cost, environmental impact, and other major noncommensurate objectives. To fully characterize the optimal trade-off solution set, one must be able to generate both supported and unsupported nondominated solutions. Fortunately, the supported, nondominated solutions are relatively easy to identify by using a single-objective shortest path algorithm in conjunction with the noninferior set estimation method of Cohon, Church, and Sheer. But, finding the unsupported nondominated solutions can be nondeterministic polynomial time hard. This article proposes a heuristic approach that is capable of determining a Pareto frontier that is very near exact in polynomial time....
The Complete Vertex p-Center Problem, 2020
The vertex p-center problem consists of locating p facilities among a set of M potential sites su... more The vertex p-center problem consists of locating p facilities among a set of M potential sites such that the maximum distance from any demand to its closest located facility is minimized. The complete vertex p-center problem solves the p-center problem for all p from 1 to the total number of sites, resulting in a multi-objective trade-off curve between the number of facilities and the service distance required to achieve full coverage. This trade-off provides a reference to planners and decision makers, enabling them to easily visualize the consequences of choosing different coverage design criteria for the given spatial configuration of the problem. We present two fast algorithms for solving the complete p-center problem: one using the classical formulation but trimming variables while still maintaining optimality and the other converting the problem to a location set covering problem and solving for all distances in the distance matrix. We also discuss scenarios where it makes sense to solve the problem via brute-force enumeration. All methods result in significant speedups, with the set covering method reducing computation times by many orders of magnitude.
Academia letters, Mar 22, 2022
The corridor location problem for determining good route alternatives for developing new infrastr... more The corridor location problem for determining good route alternatives for developing new infrastructure often requires generating many viable alternatives which may be later evaluated in public discourse. One method for generating large sets of least cost paths is by solving the kshortest path problem on a terrain network, but its usage in the literature on finding route alternatives has been limited to routing over sparse road or communication networks. We explored the use of k-shortest path techniques on the denser graph structures of GIS terrain data to examine if they are an efficient approach for corridor location problems. We found that the exponential nature of the k-shortest path problem makes this an overwhelming approach, both in terms of memory and computation time. Future work should focus on finding smart methods of reducing the problem size while retaining optimal solutions, as well as modifying the algorithms to run on high performance supercomputers in order to solve...
EURO Journal on Computational Optimization, 2020
The vertex p-center problem consists of locating p facilities among a set of M potential sites su... more The vertex p-center problem consists of locating p facilities among a set of M potential sites such that the maximum distance from any demand to its closest located facility is minimized. The complete vertex p-center problem solves the p-center problem for all p from 1 to the total number of sites, resulting in a multi-objective tradeoff curve between the number of facilities and the service distance required to achieve full coverage. This trade-off provides a reference to planners and decision-makers, enabling them to easily visualize the consequences of choosing different coverage design criteria for the given spatial configuration of the problem. We present two fast algorithms for solving the complete p-center problem, one using the classical formulation but trimming variables while still maintaining optimality, the other converting the problem to a location set covering problem and solving for all distances in the distance matrix. We also discuss scenarios where it makes sense to solve the problem via brute-force enumeration. All methods result in significant speed-ups, with the set covering method reducing computation times by many orders of magnitude.
Academia Letters, 2022
Blockchain technology has a decentralized and distributed structure enabling secure and transpare... more Blockchain technology has a decentralized and distributed structure enabling secure and transparent transactions. This technology is no longer just speculation but over the past few years has moved on to a wide range of real-world applications in finance, energy, security, and identity management. Researchers are enthusiastic about the use of its features such as decentralized storage and authentication in the healthcare industry, particularly for data management and access. Considering the different types of blockchain frameworks available (Private, Public), a private blockchain instance requiring all participants to be known would be ideal in the case of medical records. A permissioned Hyperledger such as the one implemented in Swiss hospitals to fight medical counterfeit scandals [1] is studied in case studies concerning Blockchain for health care management [2][4] support the general researcher consensus that Blockchain is indeed a great candidate for healthcare record management over traditional DBMS. A blockchain deployment would effectively enable the creation of a single means for record creation and storage. Not to mention the fact that inherent blockchain characteristics effectively meet all of the demands that the modern healthcare industry requires in terms of data storage-Security, Interoperability, Data sharing, and access.[3] This work describes the creation of a blockchain-based patient health record creation and retrieval framework 1 that will overhaul current systems in place at the same time meeting standards put in place for ensuring health data security and integrity.
pNISE is a parallelized NISE algorithm applied toward biobjective shortest path analysis on raste... more pNISE is a parallelized NISE algorithm applied toward biobjective shortest path analysis on raster grids used in Medrano & Church (2015). Serial NISE was originally published in Cohon <em>et al.</em> (1979) This is the first release intended to enable public archiving. The repository is publicly accessible at https://github.com/antoniomedrano/pNISE
This report summarizes a two-day expert meeting on “Spatial Discovery,” organized jointly by the ... more This report summarizes a two-day expert meeting on “Spatial Discovery,” organized jointly by the Library and the Center for Spatial Studies of the University of California, Santa Barbara (UCSB), and held on June 16–17, 2015 at the Upham Hotel, in Santa Barbara. The 24 participants contributed expertise in Library Science, as well as knowledge pertaining to spatial information and relevant research on data-seeking behavior. Five keynote addresses as well as several plenary and break-out discussions explored the challenges, best practices, and potential strategies associated with the cross-platform discovery of spatial data in the context of modern libraries.
Spatial analysis extracts meaning and insights from spatially referenced data, where the results ... more Spatial analysis extracts meaning and insights from spatially referenced data, where the results are highly dependent on the quality of the data used and the manipulations on the data when preparing it for analysis. Users should understand the impacts that data representations may have on their results in order to prevent distortions in their outcomes. We study the consequences of two common data preparations when locating a linear feature performing shortest path analysis on raster terrain data: 1) the connectivity of the network generated by connecting raster cells to their neighbors, and 2) the range of the attribute scale for assigning costs. Such analysis is commonly used to locate transmission lines, where the results could have major implications on project cost and its environmental impact. Experiments in solving biobjective shortest paths show that results are highly dependent on the parameters of the data representations, with exceedingly variable results based on the choi...
Geographic Information Science & Technology Body of Knowledge
Transactions in GIS, 2016
Academic libraries have always supported research across disciplines by integrating access to div... more Academic libraries have always supported research across disciplines by integrating access to diverse contents and resources. They now have the opportunity to reinvent their role in facilitating interdisciplinary work by offering researchers new ways of sharing, curating, discovering, and linking research data. Spatial data and metadata support this process because location often integrates disciplinary perspectives, enabling researchers to make their own research data more discoverable, to discover data of other researchers, and to integrate data from multiple sources. The Center for Spatial Studies at the University of California, Santa Barbara (UCSB) and the UCSB Library are undertaking joint research to better enable the discovery of research data and publications. The research addresses the question of how to spatially enable data discovery in a setting that allows for mapping and analysis in a GIS while connecting the data to publications about them. It suggests a framework for an integrated data discovery mechanism and shows how publications may be linked to associated data sets exposed either directly or through metadata on Esri's Open Data platform. The results demonstrate a simple form of linking data to publications through spatially referenced metadata and persistent identifiers. This linking adds value to research products and increases their discoverability across disciplinary boundaries.
Journal of Multi-Criteria Decision Analysis, 2015
Modern Accelerator Technologies for Geographic Information Science, 2013
Journal of Geographical Systems, 2014
ABSTRACT The problem of corridor location can be found in a number of fields including power tran... more ABSTRACT The problem of corridor location can be found in a number of fields including power transmission, highways, and pipelines. It involves the placement of a corridor or rights-of-way that traverses a landscape starting at an origin and ending at a destination. Since most systems are subject to environmental review, it is important to generate competitive, but different alternatives. This paper addresses the problem of generating efficient, spatially different alternatives to the corridor location problem. We discuss the weaknesses in current models and propose a new approach which is designed to overcome many of these problems. We present an application of this model to a real landscape and compare the results to past work. Overall, the new model called the multi-gateway shortest path problem can generate a wide variety of efficient alignments, which eclipse what could be generated by past work.
International Regional Science Review, 2014
Corridor location for developing new infrastructure such as transmission lines, roadways, and pip... more Corridor location for developing new infrastructure such as transmission lines, roadways, and pipelines over terrain must consider numerous factors when determining the set of optimal route candidates. Previous researchers have cast this problem as a multiobjective least cost path problem, where competing objectives represent cost, environmental impact, and other major noncommensurate objectives. To fully characterize the optimal trade-off solution set, one must be able to generate both supported and unsupported nondominated solutions. Fortunately, the supported, nondominated solutions are relatively easy to identify by using a single-objective shortest path algorithm in conjunction with the noninferior set estimation method of Cohon, Church, and Sheer. But, finding the unsupported nondominated solutions can be nondeterministic polynomial time hard. This article proposes a heuristic approach that is capable of determining a Pareto frontier that is very near exact in polynomial time....
The Complete Vertex p-Center Problem, 2020
The vertex p-center problem consists of locating p facilities among a set of M potential sites su... more The vertex p-center problem consists of locating p facilities among a set of M potential sites such that the maximum distance from any demand to its closest located facility is minimized. The complete vertex p-center problem solves the p-center problem for all p from 1 to the total number of sites, resulting in a multi-objective trade-off curve between the number of facilities and the service distance required to achieve full coverage. This trade-off provides a reference to planners and decision makers, enabling them to easily visualize the consequences of choosing different coverage design criteria for the given spatial configuration of the problem. We present two fast algorithms for solving the complete p-center problem: one using the classical formulation but trimming variables while still maintaining optimality and the other converting the problem to a location set covering problem and solving for all distances in the distance matrix. We also discuss scenarios where it makes sense to solve the problem via brute-force enumeration. All methods result in significant speedups, with the set covering method reducing computation times by many orders of magnitude.