Directed Graph Approach Research Articles

Normalization of drug and therapeutic concepts with Thera-Py.

The diversity of nomenclature and naming strategies makes therapeutic terminology difficult to manage and harmonize. As the number and complexity of available therapeutic ontologies continues to increase, the need for harmonized cross-resource mappings is becoming increasingly apparent. This study creates harmonized concept mappings that enable the linking together of like-concepts despite source-dependent differences in data structure or semantic representation. For this study, we created Thera-Py, a Python package and web API that constructs searchable concepts for drugs and therapeutic terminologies using 9 public resources and thesauri. By using a directed graph approach, Thera-Py captures commonly used aliases, trade names, annotations, and associations for any given therapeutic and combines them under a single concept record. We highlight the creation of 16069 unique merged therapeutic concepts from 9 distinct sources using Thera-Py and observe an increase in overlap of therapeutic concepts in 2 or more knowledge bases after harmonization using Thera-Py (9.8%-41.8%). We observe that Thera-Py tends to normalize therapeutic concepts to their underlying active ingredients (excluding nondrug therapeutics, eg, radiation therapy, biologics), and unifies all available descriptors regardless of ontological origin.

Analysis of Students Performance in Mathematics before and during Covid-19 Pandemic using PageRank: A Preliminary Study

In a normal situation, a university is constantly utilizing standard statistical analysis tools to provide a student's ranking through their academic achievement. The tools provides analysis of pairwise comparison among students on their academic performance but unfortunately visualization of the results is limited to the use of line graph, histogram, tables and boxplot which are not easily explained. In this study, another way of analyzing the pairwise comparison of academic performance on Mathematics among students is introduced that is by using interaction graph which is based on a weighted directed graph approach. The ranking of student’s performance in Mathematics is calculated using Page Rank (PR) algorithm. A sample of final examination result for twenty-one students whom enrolled in Mathematics courses in Fakulti Sains Komputer dan Matematik (FSKM), UiTM Shah Alam are investigated. Their performance by marks in two Mathematics courses taken before the pandemic and three Mathematics courses taken during the pandemic are analyzed. The graph with twenty-one nodes represent the students, while the directed links between two students represent the Mathematics relative performance is established. The rank of the students’ Mathematics performance is obtained from PR value of the graph. The largest PR value indicates the highest performance of the respective student. The result revealed that 62 percent of the students have shown better Mathematics performance even though the learning platforms before and during Covid-19 pandemic were drastically changed. Although this result does not indicate the whole picture of FSKM students' Mathematics performance, it gives a good insight to the academic administrator in making better decision. Besides, the interaction graph provides an easy way to explain the result only by looking into the graph.

Construction of Full Order-of-Addition Generalization Simplex-Centroid Designs by the Directed Graph Approach

The order-of-addition generalization simplex-centroid designs play a key role in mixture experiments, for example, the mixture experiments with process variables. The paper formally combines order-of-addition (OofA) with mixture components in the same experiment. This paper proposes a new algorithm which generates full OofA mth-degree generalization simplex-centroid designs for q components by a class of the direction graphs, and a series of examples also confirms the value of the proposed algorithm.

Novel Directed Graph Approach for Connection Optimization of the Asymmetric-Paths Winding

During the design process of the asymmetric-paths winding, the optimization between the asymmetric degree and the tidiness of end connections is still a difficulty for the existing methods. In this paper, the connection indices are proposed for the connection evaluation. In addition, a novel directed graph approach is provided for the connection optimization. It turns the connection design into the route optimization of the directed graph, including the modeling of the winding directed graph, the searching rules for a parallel path, and the matching rules between parallel paths. The winding design of a hydrogenerator is presented for the validation. The results show that the optimized scheme presents a tidy end connection, shorter circumferential busses, and a good performance in the electromagnetic field. This approach provides a new idea for the modeling of ac windings and the optimization design of the asymmetric-paths winding.

Environment-Smart Agriculture and Mapping of Interactions among Environmental Factors at the Farm Level: A Directed Graph Approach

Environment-smart agriculture (ESA) aims at sustaining increased agricultural production while limiting negative impacts on the environment. The present study develops an index of composite on-farm environmental impacts (COEI) as a proxy measure to evaluate ESA and validates the index by mapping interactions amongst agriculture related environmental impacts and potential constraints to practice ESA by using the directed graph approach. The cost of mitigation to practice ESA was calculated by estimating the cost of reducing on-farm environmental impacts by using the damage–cost method. The approach was empirically applied to a sample of 317 High Yielding Variety (HYV) rice farms from three intensive rice-growing regions of northwestern Bangladesh. Results showed that the use of chemical pesticides contributed towards higher level of uncertainty in practicing ESA than the use of chemical fertilizers, irrigation and household pollution. The combined effect of the influence from these factor interactions was estimated at 2.3, which falls in the critical region of influence and implies extreme level of uncertainty in practicing ESA. The cost of mitigating negative environmental impacts is higher for the problems of ‘decline in soil fertility’, ‘increases in crop diseases’ and ‘reduction in fish catch’ as compared to other soil and water related impacts. Policy implications include investments in addressing the problems of ‘soil fertility decline’, ‘increases in crop diseases’ and ‘reduction in fish catch’ and raising farmers’ awareness on using farm chemicals to promote ESA practices for HYV rice production.

Spatio-Temporal Complex Markov Chain (SCMC) Model Using Directed Graphs: Earthquake Sequencing

We construct a directed graph to represent a Markov chain of global earthquake sequences and analyze the statistics of transition probabilities linked to earthquake zones. We use a simplified plate boundary template for earthquake zonation. We generalize this Markov chain of earthquake sequences by including the recurrent events in space and time for each event in the record-breaking sense. The record-breaking recurrent events provide the basis for redefining the weights for the state-to-state transition probabilities. We use a distance-dependent look-up array for each zone to assign the distance-dependent weights for the recurring events. We present here details of the method and the preliminary results on the structure and properties of the directed graphs corresponding to a Markov chain model without and with the inclusion of record-breaking events. The underlying directed graph provides the framework for earthquake sequencing. We examine the properties of the directed graph without and with the inclusion of recurrences. We consider the present method easily expandable for forecasting work as catalogues are routinely updated with seismic events and, also, widely applicable to a study of both the regional and global seismicity. We demonstrate the applicability of the directed graph approach to forecasting using some of the properties of graphs that represent the Markov chain.

Modeling the Flow Pattern at the Fractured Granites in Porto Alegre, Brazil

The studied 25 by 30 km site of Porto Alegre Southern Brazil fractured granites, accounts for surface lineaments assumed to mimic its fractures. Observations address the lineaments spatial characteristics, significant deviations between stationary groundwater levels condensed at part of the domain while sparse at most of the area, and no pumping/injection rates. Fractured media feature, e.g., dead end pathways, lack of flow interconnections, and preferential infiltration paths. These characteristics are not in line with the implementation of continuum-based macroscopic balance equations. Subject to such data and the inherent features, the objective was to verify if with lumped parameter modeling (LPM) following a flow directed graph approach we can assess a groundwater flow pattern. We at first addressed the site lineaments layout for which the evaluation of the hydraulic heads revealed the existence of isolated lineament clusters, leading to flow or no-flow zones. Aiming at better spatial distribution of flow distributions and based on the site surface lineaments, we established a virtual fracture network (VFN) for which the domain was subdivided into representative elementary area (REA) cells. Each REA was chosen so that the ratio of all its lineament lengths over that of the cell area remained practically unchanged between two consecutive subdivisions. Within each REA, lineaments with similar geometrical characteristics were considered as segment groups. The VFN was established upon elongating segments that created intersection points with other stretched segments from cells at the circumference of a considered REA. The evaluated steady state hydraulic head was compared between two LPM solutions: (1) Referring to flow along the VFN branches between intersection points, and (2) Using a flux interconnected network (FIN) for which each REA was replaced by a pole communicating flow to other poles. Computation of the FIN approach was significantly less intense. Both of these approaches resolved with hydraulic head isolines consistently similar to those obtained by interpolation between the observed groundwater levels. One reported event of a Nitrate polluted well and its plausible contaminating source within the study domain, show that it is in line with the predicted resultant flow direction following the FIN map.

NextSlidePlease

Presentation support tools, such as Microsoft PowerPoint, pose challenges both in terms of creating linear presentations from complex data and fluidly navigating such linear structures when presenting to diverse audiences. NextSlidePlease is a slideware application that addresses these challenges using a directed graph structure approach for authoring and delivering multimedia presentations. The application combines novel approaches for searching and analyzing presentation datasets, composing meaningfully structured presentations, and efficiently delivering material under a variety of time constraints. We introduce and evaluate a presentation analysis algorithm intended to simplify the process of authoring dynamic presentations, and a time management and path selection algorithm that assists users in prioritizing content during the presentation process. Results from two comparative user studies indicate that the directed graph approach promotes the creation of hyperlinks, the consideration of connections between content items, and a richer understanding of the time management consequences of including and selecting presentation material.

A new directed graph approach for automated setup planning in CAPP

The task of setup planning is to determine the number and sequence of setups and the machining features or operations in each setup. Now there are three main methods for setup planning, i.e., the knowledge-based approach, the graph-based approach and the intelligence algorithm-based approach. In the knowledge-based and graph-based approaches reported in the literature, the main problem is that there is no guarantee that all precedence cycles between setups can be avoided during setup formation. The methods to break precedence cycles between setups are to split one setup into smaller setups. However, the implementation of this method is difficult and complex. In the intelligence algorithm-based approach, the method to handle the precedence constraints is a penalty strategy, which does not reflect the influence of precedence constraints on setup plans explicitly. To deal with the above deficiencies, a new directed graph approach is proposed to describe precedence constraints explicitly, which consists of three parts: (1) a setup precedence graph (SPG) to describe precedence constraints between setups. During the generation of the SPG, the minimal number of tolerance violations is guaranteed preferentially by the vertex clusters algorithm for serial vertices and the minimal number of setups is achieved by using variants of the breadth-first search. Precedence cycles between setups are avoided by checking whether two serial vertex clusters can generate a cycle; (2) operation sequencing to minimise tool changes in a setup; and (3) setup sequencing to generate optimal setup plans, which could be implemented by a topological sort. The new directed graph approach will generate many optimal or near-optimal setup plans and provide more flexibility required by different job shops. An example is illustrated to demonstrate the effect of the proposed approach.

LUBRES: An expert system development and implementation for real-time fault diagnosis of a lubricating oil refining process

An expert system LUBRES (LUBricating oil Refining Expert System) is introduced in this paper. It helps plant operators in monitoring and diagnosing of abnormal situations in refining process of lubricating oil. The LUBRES structure, the knowledge base, and the inference machine are presented in detail. A new strategy is proposed for conflicts resolution - the sorting strategy of antecedents, and a selection strategy of knowledge rules in the memory knowledge base. Knowledge acquisition mechanism is based on an empirical knowledge table, while knowledge verification is carried out based on the directed graph approach. C++Builder and SQL Server 2000 have been used in developing the proposed system. LUBRES has been successfully implemented in Microsoft Windows Server environment. For 1 year, LUBRES has been used for monitoring and diagnosing of refining process of the lubricating oil. The industrial application of LUBRES proved its high reliability and accuracy.

Lane-Based Network for Flow Analysis and Inventory Management of Transportation Networks

The widely accepted link–node centerline network model inhibits lane-based traffic analysis and inventory management, specifically the ability to represent the availability of lanes, individual lane properties, connectivity among parallel lanes and at turns, and lane movement restrictions. A lane-based network overcomes the limitations by maintaining lanes as independent topological objects and thus supports data management, decision making, and network analysis at the lane level. The data model for a lane-based network uses a directed graph approach in which a set of unidirectional lanes and nodes is used to model traffic flow connectivity. The model manages the continuous lateral connectivity between parallel lanes by specifying the relative lateral position of the lanes on their parent roadways. This approach provides an efficient way to maintain lane topology and eliminates the requirement of turntables. This paper presents the model along with guidelines for lane-based inventory management and strategies for discretizing continuous lateral connectivity between parallel lanes to enable the use of existing routing algorithms (e.g., Dijkstra's). Finally, the paper presents a practical implementation built on the linear location referencing system of a state department of transportation.

Lane-Based Network for Flow Analysis and Inventory Management of Transportation Networks

The widely accepted link-node centerline network model inhibits lanebased traffic analysis and inventory management, specifically the ability to represent the availability of lanes, individual lane properties, connectivity among parallel lanes and at turns, and lane movement restrictions. A lane-based network overcomes the limitations by maintaining lanes as independent topological objects and thus supports data management, decision making, and network analysis at the lane level. The data model for a lane-based network uses a directed graph approach in which a set of unidirectional lanes and nodes is used to model traffic flow connectivity. The model manages the continuous lateral connectivity between parallel lanes by specifying the relative lateral position of the lanes on their parent roadways. This approach provides an efficient way to maintain lane topology and eliminates the requirement of turntables. This paper presents the model along with guidelines for lane-based inventory management and strateg...

Non-Regular Maximum Likelihood Problems

SUMMARY Four non-regular estimation problems are reviewed and discussed. One (the unbounded likelihood problem) involves distributions with infinite spikes, for which maximum likelihood can fail to give consistent estimators. A comparison is made with modified likelihood and spacings methods which do give efficient estimators in this case. An application to the Box–Cox shifted power transform is given. The other three problems occur when the true parameter lies in some special subregion. In one (the constrained parameter problem) the subregion is a boundary. The other two (the embedded model and the indeterminate parameters problems) occur when the model takes on a special form in the subregion. These last two problems have previously been investigated separately. We show that they are equivalent in some situations. Both often arise in non-linear models and we give a directed graph approach which allows for their occurrence in nested model building. It is argued that many non-regular problems can be handled systematically without having to resort to elaborate technical assumptions. Relatively uncomplicated methods may be used provided that the underlying nature of the non-regularity is understood.

Production system design: A directed graph approach

Two approaches to computer aided process planning are defined—variant and generative. The variant approach retrieves existing plans for a similar part while the generative approach synthesizes plans from built-in knowledge. The generative approach to process planning is normally considered more complex and the more automated of the two approaches. This paper discusses a generative process planning system called Totally Integrated Process Planning System (TIPPS). TIPPS uses a computer aided design (CAD) model as direct input, eliminating part coding or description from the planning process. Currently, TIPPS is capable of planning prismatic parts with one access direction. Relevant issues encountered in constructing a generative process planning system as well as the TIPPS design philosophy are discussed. Process planning using TIPPS is illustrated. This paper also discusses future research directions in automated process planning.

Production system design: A directed graph approach

The problems of designing advanced production systems are considered from the viewpoints of two quite different social systems and found to be similar. The problems are characterized as being large, complex, and dynamic. Simulation is found to be a good general methodological approach, and directed graphs a particularly useful means of specifying production problem relationships for both analysis and simulation. The Appendices contain discussions of the computer systems, both based on directed graphs, in use in these countries.

A Directed Graph Approach to Locational Analysis of Fringe Residential Development

A Directed Graph Approach to Locational Analysis of Fringe Residential Development