Gabriel Alves - Academia.edu (original) (raw)

Papers by Gabriel Alves

2018 Annual IEEE International Systems Conference (SysCon), 2018

Large cities have increasing mobility problems due to the large number of vehicles on the streets... more Large cities have increasing mobility problems due to the large number of vehicles on the streets, which results in traffic jams and thus a waste of time and money. An alternative to improve traffic is to prioritize the public transportation system. Several metropolises around the world are adopting Bus Rapid Transit (BRT) systems since they present compelling results considering the cost-benefit perspective. Evaluating metrics such as performance, dependability, and performability, aids in planning, monitoring, and optimizing BRT systems. This paper presents hierarchical models, using CTMC modeling techniques, to assess metrics such as performance and performability. Results show that these models pointed to the peak intervals that are more likely to arrive at the destination in a shorter time, in addition to showing the probability of the vehicle being affected by the failure at each interval. It was also possible to establish bases for the replication of the model in different sc...

International Journal of Data Mining, Modelling and Management, 2019

Large cities have increasing mobility problems due to the large number of vehicles on the streets... more Large cities have increasing mobility problems due to the large number of vehicles on the streets, which results in traffic jams and the eventual a waste of time and resources. An alternative to improve traffic is to prioritise the public transportation system. Several metropolises around the world are adopting bus rapid transit (BRT) systems since they present compelling results considering the cost-benefit perspective. The evaluating metrics such as performance, reliability, and performability aids in the planning, monitoring, and optimising of the BRT systems. This paper presents hierarchical models, using CTMC modelling techniques, to assess metrics such as performance and performability. The results show that these models pointed to the peak intervals that are more likely to arrive at the destination in a shorter time, in addition to

International Journal of Business Process Integration and Management, 2017

Over the years, there has been an increasing pressure to improve public service, most notably, th... more Over the years, there has been an increasing pressure to improve public service, most notably, the ones that directly interact with taxpayers. However, in emerging countries, public sector is ruled by a bureaucratic structure, which complicates coordination and execution of services. Stochastic modelling provides a prominent mechanism for assessing government processes, as different configurations can be evaluated in order to enable cost reduction as well as the maximisation of service performance. This work presents an approach based on stochastic Petri nets (SPNs) for performability evaluation of government process related to taxpayer assistance centre (TAC). A real-world case study demonstrates the practical suitability of the proposed approach.

Pervasive and Mobile Computing, 2017

Mobile computing devices have improved substantially. Such a development fosters the usage of tho... more Mobile computing devices have improved substantially. Such a development fosters the usage of those devices for various purposes, including health care as a prominent example. Mobile health (mHealth) is a subfield of electronic health (eHealth) that refers to the practice of medicine and public health supported by mobile devices. A specific concern for mHealth is the limitation of power supply for the mobile devices, since interruptions on power supply can result in critical situations. This paper proposes analytical models to identify the mean time of one life cycle of the battery, and thus identify the average battery lifetime considering some device utilization characteristics. We evaluate the impact of both network connectivity (local and wide areas) and communication protocols (Polling, Long polling, WebSockets, and XMPP) on the discharging rate, and subsequently on the lifetime of batteries with different power capacities. We observed a noteworthy impact of these factors on battery usage and, thus, on mHealth applications. We use a hierarchical modeling approach that enables efficient representation of system complexity and provides accurate results for planning the autonomy of mobile devices in an mHealth context.

2015 IEEE International Conference on Systems, Man, and Cybernetics, 2015

Large cities face growing mobility problems, due to the major traffic jams that result from high ... more Large cities face growing mobility problems, due to the major traffic jams that result from high numbers of vehicles on the roads. In response, city and national governments have invested in alternative means of urban passenger transit, such as subways, trains, as well as Bus Rapid Transit (BRT). This article aims to analyze the BRT system, by attempting to calculate the probability of reaching a destination at a specific time, thereby providing a tool that can be employed to improve the system and increase passenger confidence in it. To this end, a Continuous Time Markov Chain (CTMC) model is proposed to represent the bus stations and compute the probability metric for arrival at the destination within the specified time frame. The model allows a mathematical function to calculate the probabilities for the corresponding architecture. Two case studies were conducted in order to verify the model and illustrate its potential value in the planning of BRT systems.

Lecture Notes in Computer Science, 2005

Abstract. Embedded hard real-time systems have stringent timing con-straints that must be satisfi... more Abstract. Embedded hard real-time systems have stringent timing con-straints that must be satisfied for the correct functioning of the sys-tem. Additionally, there are systems where energy is another constraint that must also be satisfied. In order to satisfy such requirements, a pre-runtime ...

2009 IEEE Symposium on Computers and Communications, 2009

The electronic funds transfer (EFT) systems promote both financial benefits for the institutions ... more The electronic funds transfer (EFT) systems promote both financial benefits for the institutions that use them and potential conveniences for their customers. EFT Systems debiting and crediting individual bank accounts from points of sale (POS) terminals in different companies and providing cash on demand 24 hours a day through automatic tellers. In the EFT system, eventual workload peaks and fluctuations

2007 IEEE International Conference on Service Operations and Logistics, and Informatics, 2007

Abstract-The global competition between companies and the requisition of high service levels for ... more Abstract-The global competition between companies and the requisition of high service levels for customers, led them to invest in the supply chain management. The outbound logistics deals with the transportation and storage of finished goods from the end of the manufacturing to ...

Proceedings of the 2nd International ICST Conference on Performance Evaluation Methodologies and Tools, 2007

Page 1. Modeling and Evaluation of Supply Chains with GSPN Components GabrielAlves Jr. Centro de ... more Page 1. Modeling and Evaluation of Supply Chains with GSPN Components GabrielAlves Jr. Centro de Informatica - Universidade Federal de Pernambuco (UFPE) Recife-PE, Brazil gaaj@cin.ufpe.br Paulo Maciel Centro de ...

Supply Chain Management - Applications and Simulations, 2011

While economic and service level indicators were adequate to show the performance of supply chain... more While economic and service level indicators were adequate to show the performance of supply chains (SCs) in the past, nowadays, environment indicators are gradually becoming more relevant (Beamon, 1999). Many prominent companies and academic research groups around the world are making efforts to provide environmentally responsible products and services. These topics are subjects of intensive study not only due to the respective impact of the production and transport systems in our planet but also particularly related to the image these companies aim to project to the society (Beamon, 1999; Srivastava, 2007). Moreover, supply chains' managers must carry about optimizing an endless number of variables that might impact costs and operational performance. These variables usually get in conflict between themselves. For instance, increasing the amount of stored goods might reduce the lead time to customers, but also increase storage costs and environment impacting resources like energy. Modelling is quite often employed for quantitative analysis of SCs (Simchi-Levi et al., 2000). One of the main advantages in use modelling techniques is the possibility of analyse "what-if" questions. Thereby, it is possible to evaluate different scenarios looking for the most optimized ones. Although the strict mathematical modelling is one of the most used approaches in the evaluation of SCs (

2008 IEEE International Conference on Systems, Man and Cybernetics, 2008

This work proposes the use of pre-defined generalized stochastic Petri net (GSPN) components to m... more This work proposes the use of pre-defined generalized stochastic Petri net (GSPN) components to model and evaluate outbound logistics. The modeling process takes into account the automatic generation of these stochastic models from high-level end-user-oriented descriptions. The model resultant from this translation is guaranteed to have some expected Petri nets' properties. The Stochastic Logistics Optimizer Tool (SLOT) was implemented with

2007 IEEE International Conference on Systems, Man and Cybernetics, 2007

Abstract—The outbound logistics can determine the success or failure of an industry. It has a hig... more Abstract—The outbound logistics can determine the success or failure of an industry. It has a high participation in overall logistics costs and is a decisive factor for the Quality of Service (QoS). Measuring this activity and evaluating possible changes will help its management ...

Proceedings of the 2005 OOPSLA workshop on Eclipse technology eXchange - eclipse '05, 2005

The lack of a standard file format to represent Petri net limits the reuse of models among Petri ... more The lack of a standard file format to represent Petri net limits the reuse of models among Petri net tools. In order to reduce the impact of this limitation the Petri Net Markup Language (PNML) has been proposed. PNML is an interchange file format for Petri nets based on XML. This paper presents a framework, called EZPetri, based on PNML. EZPetri is a perspective and a set of plug-ins of the Eclipse platform. The union of Eclipse and PNML has demonstrated itself to be an effective instrument for integrating Petri net tools and applications. The paper discusses the principles of the EZPetri, and presents one application integrated into the framework: Power Consumption Analysis Framework. Such application has been developed with no knowledge about EZPetri. This is a demonstration of the integration facilities provided by the framework. EZPetri is thus a fertile ground for combining existing Petri net tools and applications into a single environment, offering the Petri net community a new perspective of integration.

2014 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2014

Over the years, inbound logistics has been prominent to many industries, as globalization has for... more Over the years, inbound logistics has been prominent to many industries, as globalization has forced companies to increase productivity while reducing costs. Transport modes considerably impact the costs, and a proper evaluation should consider performance, failures as well as sustainability issues. This paper presents an approach based on stochastic Petri nets (SPN) for assessing different transport modes in inbound logistics for coffee industry taking into account performability and sustainability.

International Journal of Services Operations and Informatics, 2008

The outbound logistics deals with the transportation and storage of finished goods. It is one of ... more The outbound logistics deals with the transportation and storage of finished goods. It is one of the most complex and expensive activity of the supply chain management and is decisive for the Quality of Service (QoS). This paper proposes the use of pre-defined Petri net components to model and evaluate this activity. The model that represents an outbound logistics scenario is obtained with a bottom-up approach, guaranteeing some expected Petri nets properties. Furthermore, the use of pre-defined, validated components allows modelling and evaluating the supply chain entities and processes through a systematic procedure. In the end of this paper, results related to a real case study, conducted by considering the proposed models, is depicted.

IEEE Transactions on Systems, Man, and Cybernetics - Part A: Systems and Humans, 2010

Abstract—This paper proposes a methodology for modeling and evaluating supply chains based on gen... more Abstract—This paper proposes a methodology for modeling and evaluating supply chains based on generalized stochastic Petri net (GSPN) components. The proposed modeling process is based on a bottom–up approach, which assures desirable model properties that start ...

Electronic Notes in Theoretical Computer Science, 2011

Supply chains (SCs) are one of the most environment impacting systems. Analysis of such systems s... more Supply chains (SCs) are one of the most environment impacting systems. Analysis of such systems should thus take into account not only performance but also environment indicators. The amount of energy consumed for producing goods and the total emissions of greenhouse gases (GHG) of an activity are examples of such indicators. This paper presents a framework for assessing performance as well as Global Warming Potential (GWP) and exergy indicators in SCs. In order, exergy accounting helps on finding reliable GWP indicators for different energy sources adopted in the supply chain. This framework supports the evaluation of supply chains' business and environment indicators trade-offs using a unified model. A real case study is conducted to demonstrate the application of the proposed modeling technique.

Page 1. IEEE Workshop on Performance evaluation of communications in distributed systems and Web ... more Page 1. IEEE Workshop on Performance evaluation of communications in distributed systems and Web based service architectures 2009 Table of Contents Comparison ofComputation Methods for the Steady-State Markov Modulated Fluid Queues Wassim Abbessi and Hedi Nabli. Stochastic Bounds for Performance Evaluation of Web Services 7 Jean-Michel Fourneau, Lynda Mokdad and Nihal Pekergin. Transcient States analysis diffusion approximation as an Alternative to markov chain fluid flow 13 ...

2018 Annual IEEE International Systems Conference (SysCon), 2018

Large cities have increasing mobility problems due to the large number of vehicles on the streets... more Large cities have increasing mobility problems due to the large number of vehicles on the streets, which results in traffic jams and thus a waste of time and money. An alternative to improve traffic is to prioritize the public transportation system. Several metropolises around the world are adopting Bus Rapid Transit (BRT) systems since they present compelling results considering the cost-benefit perspective. Evaluating metrics such as performance, dependability, and performability, aids in planning, monitoring, and optimizing BRT systems. This paper presents hierarchical models, using CTMC modeling techniques, to assess metrics such as performance and performability. Results show that these models pointed to the peak intervals that are more likely to arrive at the destination in a shorter time, in addition to showing the probability of the vehicle being affected by the failure at each interval. It was also possible to establish bases for the replication of the model in different sc...

International Journal of Data Mining, Modelling and Management, 2019

Large cities have increasing mobility problems due to the large number of vehicles on the streets... more Large cities have increasing mobility problems due to the large number of vehicles on the streets, which results in traffic jams and the eventual a waste of time and resources. An alternative to improve traffic is to prioritise the public transportation system. Several metropolises around the world are adopting bus rapid transit (BRT) systems since they present compelling results considering the cost-benefit perspective. The evaluating metrics such as performance, reliability, and performability aids in the planning, monitoring, and optimising of the BRT systems. This paper presents hierarchical models, using CTMC modelling techniques, to assess metrics such as performance and performability. The results show that these models pointed to the peak intervals that are more likely to arrive at the destination in a shorter time, in addition to

International Journal of Business Process Integration and Management, 2017

Over the years, there has been an increasing pressure to improve public service, most notably, th... more Over the years, there has been an increasing pressure to improve public service, most notably, the ones that directly interact with taxpayers. However, in emerging countries, public sector is ruled by a bureaucratic structure, which complicates coordination and execution of services. Stochastic modelling provides a prominent mechanism for assessing government processes, as different configurations can be evaluated in order to enable cost reduction as well as the maximisation of service performance. This work presents an approach based on stochastic Petri nets (SPNs) for performability evaluation of government process related to taxpayer assistance centre (TAC). A real-world case study demonstrates the practical suitability of the proposed approach.

Pervasive and Mobile Computing, 2017

Mobile computing devices have improved substantially. Such a development fosters the usage of tho... more Mobile computing devices have improved substantially. Such a development fosters the usage of those devices for various purposes, including health care as a prominent example. Mobile health (mHealth) is a subfield of electronic health (eHealth) that refers to the practice of medicine and public health supported by mobile devices. A specific concern for mHealth is the limitation of power supply for the mobile devices, since interruptions on power supply can result in critical situations. This paper proposes analytical models to identify the mean time of one life cycle of the battery, and thus identify the average battery lifetime considering some device utilization characteristics. We evaluate the impact of both network connectivity (local and wide areas) and communication protocols (Polling, Long polling, WebSockets, and XMPP) on the discharging rate, and subsequently on the lifetime of batteries with different power capacities. We observed a noteworthy impact of these factors on battery usage and, thus, on mHealth applications. We use a hierarchical modeling approach that enables efficient representation of system complexity and provides accurate results for planning the autonomy of mobile devices in an mHealth context.

2015 IEEE International Conference on Systems, Man, and Cybernetics, 2015

Large cities face growing mobility problems, due to the major traffic jams that result from high ... more Large cities face growing mobility problems, due to the major traffic jams that result from high numbers of vehicles on the roads. In response, city and national governments have invested in alternative means of urban passenger transit, such as subways, trains, as well as Bus Rapid Transit (BRT). This article aims to analyze the BRT system, by attempting to calculate the probability of reaching a destination at a specific time, thereby providing a tool that can be employed to improve the system and increase passenger confidence in it. To this end, a Continuous Time Markov Chain (CTMC) model is proposed to represent the bus stations and compute the probability metric for arrival at the destination within the specified time frame. The model allows a mathematical function to calculate the probabilities for the corresponding architecture. Two case studies were conducted in order to verify the model and illustrate its potential value in the planning of BRT systems.

Lecture Notes in Computer Science, 2005

Abstract. Embedded hard real-time systems have stringent timing con-straints that must be satisfi... more Abstract. Embedded hard real-time systems have stringent timing con-straints that must be satisfied for the correct functioning of the sys-tem. Additionally, there are systems where energy is another constraint that must also be satisfied. In order to satisfy such requirements, a pre-runtime ...

2009 IEEE Symposium on Computers and Communications, 2009

The electronic funds transfer (EFT) systems promote both financial benefits for the institutions ... more The electronic funds transfer (EFT) systems promote both financial benefits for the institutions that use them and potential conveniences for their customers. EFT Systems debiting and crediting individual bank accounts from points of sale (POS) terminals in different companies and providing cash on demand 24 hours a day through automatic tellers. In the EFT system, eventual workload peaks and fluctuations

2007 IEEE International Conference on Service Operations and Logistics, and Informatics, 2007

Abstract-The global competition between companies and the requisition of high service levels for ... more Abstract-The global competition between companies and the requisition of high service levels for customers, led them to invest in the supply chain management. The outbound logistics deals with the transportation and storage of finished goods from the end of the manufacturing to ...

Proceedings of the 2nd International ICST Conference on Performance Evaluation Methodologies and Tools, 2007

Page 1. Modeling and Evaluation of Supply Chains with GSPN Components GabrielAlves Jr. Centro de ... more Page 1. Modeling and Evaluation of Supply Chains with GSPN Components GabrielAlves Jr. Centro de Informatica - Universidade Federal de Pernambuco (UFPE) Recife-PE, Brazil gaaj@cin.ufpe.br Paulo Maciel Centro de ...

Supply Chain Management - Applications and Simulations, 2011

While economic and service level indicators were adequate to show the performance of supply chain... more While economic and service level indicators were adequate to show the performance of supply chains (SCs) in the past, nowadays, environment indicators are gradually becoming more relevant (Beamon, 1999). Many prominent companies and academic research groups around the world are making efforts to provide environmentally responsible products and services. These topics are subjects of intensive study not only due to the respective impact of the production and transport systems in our planet but also particularly related to the image these companies aim to project to the society (Beamon, 1999; Srivastava, 2007). Moreover, supply chains' managers must carry about optimizing an endless number of variables that might impact costs and operational performance. These variables usually get in conflict between themselves. For instance, increasing the amount of stored goods might reduce the lead time to customers, but also increase storage costs and environment impacting resources like energy. Modelling is quite often employed for quantitative analysis of SCs (Simchi-Levi et al., 2000). One of the main advantages in use modelling techniques is the possibility of analyse "what-if" questions. Thereby, it is possible to evaluate different scenarios looking for the most optimized ones. Although the strict mathematical modelling is one of the most used approaches in the evaluation of SCs (

2008 IEEE International Conference on Systems, Man and Cybernetics, 2008

This work proposes the use of pre-defined generalized stochastic Petri net (GSPN) components to m... more This work proposes the use of pre-defined generalized stochastic Petri net (GSPN) components to model and evaluate outbound logistics. The modeling process takes into account the automatic generation of these stochastic models from high-level end-user-oriented descriptions. The model resultant from this translation is guaranteed to have some expected Petri nets' properties. The Stochastic Logistics Optimizer Tool (SLOT) was implemented with

2007 IEEE International Conference on Systems, Man and Cybernetics, 2007

Abstract—The outbound logistics can determine the success or failure of an industry. It has a hig... more Abstract—The outbound logistics can determine the success or failure of an industry. It has a high participation in overall logistics costs and is a decisive factor for the Quality of Service (QoS). Measuring this activity and evaluating possible changes will help its management ...

Proceedings of the 2005 OOPSLA workshop on Eclipse technology eXchange - eclipse '05, 2005

The lack of a standard file format to represent Petri net limits the reuse of models among Petri ... more The lack of a standard file format to represent Petri net limits the reuse of models among Petri net tools. In order to reduce the impact of this limitation the Petri Net Markup Language (PNML) has been proposed. PNML is an interchange file format for Petri nets based on XML. This paper presents a framework, called EZPetri, based on PNML. EZPetri is a perspective and a set of plug-ins of the Eclipse platform. The union of Eclipse and PNML has demonstrated itself to be an effective instrument for integrating Petri net tools and applications. The paper discusses the principles of the EZPetri, and presents one application integrated into the framework: Power Consumption Analysis Framework. Such application has been developed with no knowledge about EZPetri. This is a demonstration of the integration facilities provided by the framework. EZPetri is thus a fertile ground for combining existing Petri net tools and applications into a single environment, offering the Petri net community a new perspective of integration.

2014 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2014

Over the years, inbound logistics has been prominent to many industries, as globalization has for... more Over the years, inbound logistics has been prominent to many industries, as globalization has forced companies to increase productivity while reducing costs. Transport modes considerably impact the costs, and a proper evaluation should consider performance, failures as well as sustainability issues. This paper presents an approach based on stochastic Petri nets (SPN) for assessing different transport modes in inbound logistics for coffee industry taking into account performability and sustainability.

International Journal of Services Operations and Informatics, 2008

The outbound logistics deals with the transportation and storage of finished goods. It is one of ... more The outbound logistics deals with the transportation and storage of finished goods. It is one of the most complex and expensive activity of the supply chain management and is decisive for the Quality of Service (QoS). This paper proposes the use of pre-defined Petri net components to model and evaluate this activity. The model that represents an outbound logistics scenario is obtained with a bottom-up approach, guaranteeing some expected Petri nets properties. Furthermore, the use of pre-defined, validated components allows modelling and evaluating the supply chain entities and processes through a systematic procedure. In the end of this paper, results related to a real case study, conducted by considering the proposed models, is depicted.

IEEE Transactions on Systems, Man, and Cybernetics - Part A: Systems and Humans, 2010

Abstract—This paper proposes a methodology for modeling and evaluating supply chains based on gen... more Abstract—This paper proposes a methodology for modeling and evaluating supply chains based on generalized stochastic Petri net (GSPN) components. The proposed modeling process is based on a bottom–up approach, which assures desirable model properties that start ...

Electronic Notes in Theoretical Computer Science, 2011

Supply chains (SCs) are one of the most environment impacting systems. Analysis of such systems s... more Supply chains (SCs) are one of the most environment impacting systems. Analysis of such systems should thus take into account not only performance but also environment indicators. The amount of energy consumed for producing goods and the total emissions of greenhouse gases (GHG) of an activity are examples of such indicators. This paper presents a framework for assessing performance as well as Global Warming Potential (GWP) and exergy indicators in SCs. In order, exergy accounting helps on finding reliable GWP indicators for different energy sources adopted in the supply chain. This framework supports the evaluation of supply chains' business and environment indicators trade-offs using a unified model. A real case study is conducted to demonstrate the application of the proposed modeling technique.

Page 1. IEEE Workshop on Performance evaluation of communications in distributed systems and Web ... more Page 1. IEEE Workshop on Performance evaluation of communications in distributed systems and Web based service architectures 2009 Table of Contents Comparison ofComputation Methods for the Steady-State Markov Modulated Fluid Queues Wassim Abbessi and Hedi Nabli. Stochastic Bounds for Performance Evaluation of Web Services 7 Jean-Michel Fourneau, Lynda Mokdad and Nihal Pekergin. Transcient States analysis diffusion approximation as an Alternative to markov chain fluid flow 13 ...