Ponències/Comunicacions de congressos
http://hdl.handle.net/2117/3323
2017-05-28T16:43:37ZA second order cone formulation of continuous CTA model
http://hdl.handle.net/2117/103229
A second order cone formulation of continuous CTA model
Lesaja, Goran; Castro Pérez, Jordi; Oganian, Anna
In this paper we consider a minimum distance Controlled Tabular Adjustment (CTA) model for statistical disclosure limitation (control) of tabular data. The goal of the CTA model is to find the closest safe table to some original tabular data set that contains sensitive information. The measure of closeness is usually measured using l1 or l2 norm; with each measure having its advantages and disadvantages. Recently, in [4] a regularization of the l1 -CTA using Pseudo-Huber func- tion was introduced in an attempt to combine positive characteristics of both l1 -CTA and l2 -CTA. All three models can be solved using appro- priate versions of Interior-Point Methods (IPM). It is known that IPM in general works better on well structured problems such as conic op- timization problems, thus, reformulation of these CTA models as conic optimization problem may be advantageous. We present reformulation of Pseudo-Huber-CTA, and l1 -CTA as Second-Order Cone (SOC) op- timization problems and test the validity of the approach on the small example of two-dimensional tabular data set.
The final publication is available at link.springer.com
2017-04-03T14:27:25ZLesaja, GoranCastro Pérez, JordiOganian, AnnaIn this paper we consider a minimum distance Controlled Tabular Adjustment (CTA) model for statistical disclosure limitation (control) of tabular data. The goal of the CTA model is to find the closest safe table to some original tabular data set that contains sensitive information. The measure of closeness is usually measured using l1 or l2 norm; with each measure having its advantages and disadvantages. Recently, in [4] a regularization of the l1 -CTA using Pseudo-Huber func- tion was introduced in an attempt to combine positive characteristics of both l1 -CTA and l2 -CTA. All three models can be solved using appro- priate versions of Interior-Point Methods (IPM). It is known that IPM in general works better on well structured problems such as conic op- timization problems, thus, reformulation of these CTA models as conic optimization problem may be advantageous. We present reformulation of Pseudo-Huber-CTA, and l1 -CTA as Second-Order Cone (SOC) op- timization problems and test the validity of the approach on the small example of two-dimensional tabular data set.Revisiting interval protection, a.k.a. partial cell suppression, for tabular data
http://hdl.handle.net/2117/103224
Revisiting interval protection, a.k.a. partial cell suppression, for tabular data
Castro Pérez, Jordi; Via Baraldés, Anna
Interval protection or partial cell suppression was introduced in “M. Fischetti, J.-J. Salazar, Partial cell suppression: A new methodology for statistical disclosure control, Statistics and Computing, 13, 13–21, 2003” as a “linearization” of the difficult cell suppression problem. Interval protection replaces some cells by intervals containing the original cell value, unlike in cell suppression where the values are suppressed. Although the resulting optimization problem is still huge—as in cell suppression, it is linear, thus allowing the application of efficient procedures. In this work we present preliminary results with a prototype implementation of Benders decomposition for interval protection. Although the above seminal publication about partial cell suppression applied a similar methodology, our approach differs in two aspects: (i) the boundaries of the intervals are completely independent in our implementation, whereas the one of 2003 solved a simpler variant where boundaries must satisfy a certain ratio; (ii) our prototype is applied to a set of seven general and hierarchical tables, whereas only three two-dimensional tables were solved with the implementation of 2003.
The final publication is available at link.springer.com
2017-04-03T13:07:52ZCastro Pérez, JordiVia Baraldés, AnnaInterval protection or partial cell suppression was introduced in “M. Fischetti, J.-J. Salazar, Partial cell suppression: A new methodology for statistical disclosure control, Statistics and Computing, 13, 13–21, 2003” as a “linearization” of the difficult cell suppression problem. Interval protection replaces some cells by intervals containing the original cell value, unlike in cell suppression where the values are suppressed. Although the resulting optimization problem is still huge—as in cell suppression, it is linear, thus allowing the application of efficient procedures. In this work we present preliminary results with a prototype implementation of Benders decomposition for interval protection. Although the above seminal publication about partial cell suppression applied a similar methodology, our approach differs in two aspects: (i) the boundaries of the intervals are completely independent in our implementation, whereas the one of 2003 solved a simpler variant where boundaries must satisfy a certain ratio; (ii) our prototype is applied to a set of seven general and hierarchical tables, whereas only three two-dimensional tables were solved with the implementation of 2003.An evaluation of urban consolidation centers through continuous analysis with non-equal market share companies
http://hdl.handle.net/2117/100390
An evaluation of urban consolidation centers through continuous analysis with non-equal market share companies
Roca Riu, Mireia; Estrada Romeu, Miguel Ángel; Fernández Aréizaga, Elena
This paper analyzes the logistic cost savings caused by the implementation of Urban Consolidation Centers (UCC) in a dense area of a city. In these urban terminals, freight flows from interurban carriers are consolidated and transferred to a neutral last-mile carrier to perform final deliveries. This operation would reduce both last-mile fleet size and average distance cost. Our UCC modeling approach is focused on continuous analytic models for the general case of carriers with different market shares. Savings are highly sensitive to the design of the system: the increment of capacity in interurban vehicles and the proximity of the UCC terminal to the area in relation to current distribution centers. An exhaustive collection of possible market shares distributions are discussed. Results show that market shares distribution does not affect cost savings significantly. The analysis of the proposed model also highlights the trade-off between savings in the system and a minimum market share per company when the consolidation center is established.
2017-01-31T15:28:37ZRoca Riu, MireiaEstrada Romeu, Miguel ÁngelFernández Aréizaga, ElenaThis paper analyzes the logistic cost savings caused by the implementation of Urban Consolidation Centers (UCC) in a dense area of a city. In these urban terminals, freight flows from interurban carriers are consolidated and transferred to a neutral last-mile carrier to perform final deliveries. This operation would reduce both last-mile fleet size and average distance cost. Our UCC modeling approach is focused on continuous analytic models for the general case of carriers with different market shares. Savings are highly sensitive to the design of the system: the increment of capacity in interurban vehicles and the proximity of the UCC terminal to the area in relation to current distribution centers. An exhaustive collection of possible market shares distributions are discussed. Results show that market shares distribution does not affect cost savings significantly. The analysis of the proposed model also highlights the trade-off between savings in the system and a minimum market share per company when the consolidation center is established.Diseño de rutas de recogida de residuos sólidos urbanos en el área metropolitana de Barcelona
http://hdl.handle.net/2117/90193
Diseño de rutas de recogida de residuos sólidos urbanos en el área metropolitana de Barcelona
Bautista Valhondo, Joaquín; Pereira Gude, Jordi; Fernández Aréizaga, Elena
Los problemas aso ciados a la recogida de residuos sólidos urbanos son muy variados. En este traba jo se presenta el problema de diseño de itinerarios de recogida y se muestran los resultados ofrecidos p or un pro cedimiento basado en colonias de hormigas a la recogida en un núcleo urbano del Área Metrop olitana de Barcelona.
2016-09-26T11:33:11ZBautista Valhondo, JoaquínPereira Gude, JordiFernández Aréizaga, ElenaLos problemas aso ciados a la recogida de residuos sólidos urbanos son muy variados. En este traba jo se presenta el problema de diseño de itinerarios de recogida y se muestran los resultados ofrecidos p or un pro cedimiento basado en colonias de hormigas a la recogida en un núcleo urbano del Área Metrop olitana de Barcelona.Numerical implementation and computational results of nonlinear network optimization with linear side constraints
http://hdl.handle.net/2117/89385
Numerical implementation and computational results of nonlinear network optimization with linear side constraints
Heredia, F.-Javier (Francisco Javier); Nabona Francisco, Narcís
2016-08-25T13:03:53ZHeredia, F.-Javier (Francisco Javier)Nabona Francisco, NarcísOptimal location of fast charging stations in Barcelona: a flow-capturing approach
http://hdl.handle.net/2117/89381
Optimal location of fast charging stations in Barcelona: a flow-capturing approach
Cruz Zambrano, Miguel; Corchero García, Cristina; Igualada González, Lucía; Bernardo, Valeria
The aim of this paper is to find the optimal location of electric vehicle (EV) fast charging stations by means of two methodologies: a classical flow-capturing optimization model involving only mobility needs, and an advanced flow-capturing optimization model including distribution network and location costs. While the first model aims to maximize the public service provided by the fast charging stations, the second also considers the incurred cost for providing it. Results from both models are compared in order to analyse the effect of both planning approaches in total cost of installation. As a case study it has been chosen the city of Barcelona.
2016-08-24T08:57:52ZCruz Zambrano, MiguelCorchero García, CristinaIgualada González, LucíaBernardo, ValeriaThe aim of this paper is to find the optimal location of electric vehicle (EV) fast charging stations by means of two methodologies: a classical flow-capturing optimization model involving only mobility needs, and an advanced flow-capturing optimization model including distribution network and location costs. While the first model aims to maximize the public service provided by the fast charging stations, the second also considers the incurred cost for providing it. Results from both models are compared in order to analyse the effect of both planning approaches in total cost of installation. As a case study it has been chosen the city of Barcelona.A stochastic programming model for the tertiary control of microgrids
http://hdl.handle.net/2117/87023
A stochastic programming model for the tertiary control of microgrids
Citores, Leire; Corchero García, Cristina; Heredia, F.-Javier (Francisco Javier)
In this work a scenario-based two-stage stochastic programming model is proposed to solve a microgrid’s tertiary control optimization problem taking into account some renewable energy resource’s uncertainty as well as uncertain energy deviation prices in the electricity market. Scenario generation methods for wind speed realizations are also studied. Results show that the introduction of stochastic programming represents a significant improvement over a deterministic model.
2016-05-12T14:15:37ZCitores, LeireCorchero García, CristinaHeredia, F.-Javier (Francisco Javier)In this work a scenario-based two-stage stochastic programming model is proposed to solve a microgrid’s tertiary control optimization problem taking into account some renewable energy resource’s uncertainty as well as uncertain energy deviation prices in the electricity market. Scenario generation methods for wind speed realizations are also studied. Results show that the introduction of stochastic programming represents a significant improvement over a deterministic model.Potential externalities savings due to electric vehicle smart charge
http://hdl.handle.net/2117/86395
Potential externalities savings due to electric vehicle smart charge
Benveniste Pérez, Gabriela; Corchero García, Cristina; Cruz Zambrano, Miguel
This work focuses on the analysis developed in order to demonstrate how smart charging, using tailored control algorithms, contributes to minimize the environmental impact and economic costs associated to the electric vehicles under an LCA perspective. The analysis considers the Spanish grid mix profile and specific charging patterns.The LCA methodology adopted implies a comprehensive assessment of the impacts and costs occurring upstream and downstream the charging event. For the environmental analysis, the LCA impact categories are considered, while for the economic assessment, data regarding the costs associated to the electricity price and the pollutants generation have been adopted.
2016-04-28T15:17:03ZBenveniste Pérez, GabrielaCorchero García, CristinaCruz Zambrano, MiguelThis work focuses on the analysis developed in order to demonstrate how smart charging, using tailored control algorithms, contributes to minimize the environmental impact and economic costs associated to the electric vehicles under an LCA perspective. The analysis considers the Spanish grid mix profile and specific charging patterns.The LCA methodology adopted implies a comprehensive assessment of the impacts and costs occurring upstream and downstream the charging event. For the environmental analysis, the LCA impact categories are considered, while for the economic assessment, data regarding the costs associated to the electricity price and the pollutants generation have been adopted.European electric vehicle fleet: driving and charging behaviors
http://hdl.handle.net/2117/86393
European electric vehicle fleet: driving and charging behaviors
Corchero García, Cristina
The electrification of vehicles would be a reality in the coming decades. Statistical results on real electric vehicle usage data is a key point in the development of the electro mobility. A large collection of electric vehicles and charging points have been monitored during three years and the results about the driving and charging patterns are shown in this work. These results may help to develop future policies on, for instance, charging infrastructure location, end-users incentives, or to allow different type of economic analysis such as an evaluation of the electric vehicle integration in the grid, smart-charge impact…
2016-04-28T15:10:46ZCorchero García, CristinaThe electrification of vehicles would be a reality in the coming decades. Statistical results on real electric vehicle usage data is a key point in the development of the electro mobility. A large collection of electric vehicles and charging points have been monitored during three years and the results about the driving and charging patterns are shown in this work. These results may help to develop future policies on, for instance, charging infrastructure location, end-users incentives, or to allow different type of economic analysis such as an evaluation of the electric vehicle integration in the grid, smart-charge impact…Using BCD-CTA for difficult tables: a practical experiment with a real Eurostat table
http://hdl.handle.net/2117/83503
Using BCD-CTA for difficult tables: a practical experiment with a real Eurostat table
Castro Pérez, Jordi; González Alastrué, José Antonio; Hundepool, Anco
CTA is a post-tabular perturbative approach for statistical disclosure control. Its purpose is to compute the closest safe table to the original data, using some distance.
Sensitive cells are adjusted either upwards or downwards (binary decision), and the resulting cells have to be accordingly (and minimally) modi_ed to preserve marginals. For real and large tables, CTA may result in a dicult mixed integer linear problem for some
weights in the objective function. In those situations the Block Coordinate Descent (BCD) heuristic for CTA|which is included in the Tau-Argus CTA distribution|may be used to quickly obtain a feasible, hopefully close to optimality, solution. We present a practical experiment using a large and di_cult real-world table from Eurostat. We will show that, for unitary weights, while the standard CTA can not obtain a solution in about half an hour, the BCD-CTA approach provides a solution in few seconds.
2016-02-26T15:41:16ZCastro Pérez, JordiGonzález Alastrué, José AntonioHundepool, AncoCTA is a post-tabular perturbative approach for statistical disclosure control. Its purpose is to compute the closest safe table to the original data, using some distance.
Sensitive cells are adjusted either upwards or downwards (binary decision), and the resulting cells have to be accordingly (and minimally) modi_ed to preserve marginals. For real and large tables, CTA may result in a dicult mixed integer linear problem for some
weights in the objective function. In those situations the Block Coordinate Descent (BCD) heuristic for CTA|which is included in the Tau-Argus CTA distribution|may be used to quickly obtain a feasible, hopefully close to optimality, solution. We present a practical experiment using a large and di_cult real-world table from Eurostat. We will show that, for unitary weights, while the standard CTA can not obtain a solution in about half an hour, the BCD-CTA approach provides a solution in few seconds.