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See detailOptimal Priority Assignment for Real-Time Systems: A Coevolution-Based Approach
Lee, Jaekwon UL; Shin, Seung Yeob UL; Nejati, Shiva et al

in Empirical Software Engineering (2022), 27

In real-time systems, priorities assigned to real-time tasks determine the order of task executions, by relying on an underlying task scheduling policy. Assigning optimal priority values to tasks is ... [more ▼]

In real-time systems, priorities assigned to real-time tasks determine the order of task executions, by relying on an underlying task scheduling policy. Assigning optimal priority values to tasks is critical to allow the tasks to complete their executions while maximizing safety margins from their specified deadlines. This enables real-time systems to tolerate unexpected overheads in task executions and still meet their deadlines. In practice, priority assignments result from an interactive process between the development and testing teams. In this article, we propose an automated method that aims to identify the best possible priority assignments in real-time systems, accounting for multiple objectives regarding safety margins and engineering constraints. Our approach is based on a multi-objective, competitive coevolutionary algorithm mimicking the interactive priority assignment process between the development and testing teams. We evaluate our approach by applying it to six industrial systems from different domains and several synthetic systems. The results indicate that our approach significantly outperforms both our baselines, i.e., random search and sequential search, and solutions defined by practitioners. Our approach scales to complex industrial systems as an offline analysis method that attempts to find near-optimal solutions within acceptable time, i.e., less than 16 hours. [less ▲]

Detailed reference viewed: 98 (31 UL)
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See detailOptimal Randomized Partial Checking for Decryption Mix Nets
Haines, Thomas; Mueller, Johannes UL

in Information Security and Privacy - 26th Australasian Conference, ACISP 2021, Virtual Event, December 1-3, 2021, Proceedings (2021)

Detailed reference viewed: 41 (0 UL)
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See detailOptimal rank-based inference for spherical location
Ley, Christophe; Swan, Yvik UL; Thiam, Baba et al

in Statistica Sinica (2013), 23

Detailed reference viewed: 41 (0 UL)
See detailOptimal rates, Fourth Moment Theorems and non-linear functionals of Brownian local times
Campese, Simon UL

Doctoral thesis (2014)

The present dissertation provides contributions to three distinct topics of modern stochastic analysis, namely: (a) optimal rates of convergence in multidimensional central limit theorems (CLTs) on a ... [more ▼]

The present dissertation provides contributions to three distinct topics of modern stochastic analysis, namely: (a) optimal rates of convergence in multidimensional central limit theorems (CLTs) on a Gaussian space, (b) Fourth Moment Theorems (and associated multidimensional generalisations) in the framework of the chaos of a Markov generator and (c) CLTs for non-linear functionals of Brownian local times. [less ▲]

Detailed reference viewed: 333 (42 UL)
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See detailOptimal Relay Selection Strategy for Joint Data and Energy Transfer in Wireless Systems
Gautam, Sumit UL; Lagunas, Eva UL; Chatzinotas, Symeon UL et al

Presentation (2018, April 17)

We study a problem of relay selection in a two-hop amplify-and-forward (AF) enabled relaying network for facilitating simultaneous Wireless Transmission of Information and Energy (Wi-TIE) to a destination ... [more ▼]

We study a problem of relay selection in a two-hop amplify-and-forward (AF) enabled relaying network for facilitating simultaneous Wireless Transmission of Information and Energy (Wi-TIE) to a destination able to perform both information processing and energy harvesting concurrently. Considering the time switching (TS) and power splitting (PS) based Wi-TIE schemes, we formulate an optimization problem to maximize the overall user data rate while ensuring a minimum harvested power. In this context, we obtain suitable closed form solution and demonstrate through simulation results the Rate-Energy (R-E) trade-off in two different scenarios: (i) with only the relay assisted link, and (ii) with the direct link together with the relay assisted link. [less ▲]

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See detailOptimal Resource Allocation for NOMA-Enabled Cache Replacement and Content Delivery
Lei, Lei UL; Vu, Thang Xuan UL; Xiang, Lin UL et al

in IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (IEEE PIMRC 2019) (2019, September)

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See detailAn Optimal Sensor Placement Algorithm taking into account Diagnosability Specifications
Yassine, Abed Alrahim; Rosich, Albert UL; Ploix, Stéphane

in Automation Quality and Testing Robotics (AQTR), 2010 IEEE International Conference on (Volume:2 (2010)

Suitable installed sensors in a industrial process is a necessary condition for fault diagnosis. Sensor placement for diagnosis purposes is to study which process variables have to be measured to satisfy ... [more ▼]

Suitable installed sensors in a industrial process is a necessary condition for fault diagnosis. Sensor placement for diagnosis purposes is to study which process variables have to be measured to satisfy diagnosis specifications (detectability, dis-criminability and diagnosability). This paper presents a method based on the study of the structural model properties and the Dulmage-Mendelsohn decomposition. Due to the use of structural models, the proposed approach can be applied to a wide variety of system (linear, algebraic, dynamics, etc.). Assuming that the cost of placing a sensor for each possible variable is defined, this method finds the minimal cost sensor configuration according to the diagnosability criteria. This method does not require the computation of testable subsystems [less ▲]

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See detailOptimal Sensor Placement for FDI using Binary Integer Linear Programming
Rosich, Albert UL; Sarrate, Ramon; Nejjari, Fatiha

in 20th International Workshop on Principles of Diagnosis (2009)

This work is devoted to find an optimal set of sensors for model-based FDI. The novelty is that linary integer linear programming is used in the optimization problem, leading to a formulation of the ... [more ▼]

This work is devoted to find an optimal set of sensors for model-based FDI. The novelty is that linary integer linear programming is used in the optimization problem, leading to a formulation of the detectability and isolability specifications as linear inequality constraints. Furthermore, a very detailed system model is not needed since the methodology handles structural models. The approach has been successfully applied to a two-tank system, as an illustrative example. [less ▲]

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See detailOptimal Sensor Placement For Fuel Cell System Diagnosis using BILP Formulation
Nejjari, Fatiha; Sarrate, Ramon; Rosich, Albert UL

in Control & Automation (MED), 2010 18th Mediterranean Conference on (2010)

This paper presents the application of a new methodology for Fault Detection and Isolation (FDI) to a Fuel Cell System. The work is devoted to find an optimal set of sensors for model-based FDI. The ... [more ▼]

This paper presents the application of a new methodology for Fault Detection and Isolation (FDI) to a Fuel Cell System. The work is devoted to find an optimal set of sensors for model-based FDI. The novelty is that binary integer linear programming (BILP) is used in the optimization formulation, leading to a reformulation of the detectability and isolability specifications as linear inequality constraints. The approach has been successfully applied to a Fuel Cell System. [less ▲]

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See detailOptimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms
Casillas, Myrna V.; Puig, Vicenç; Garza-Castañon, Luis E. et al

in 2nd International Conference on Control and Fault-Tolerant Systems (2013)

In this paper, a new approach for sensor placement in water distribution networks (WDN) is proposed. The sensor placement problem is formulated as an integer optimization problem. The optimization ... [more ▼]

In this paper, a new approach for sensor placement in water distribution networks (WDN) is proposed. The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the non-linear integer and large-scale nature of the resulting optimization problem, genetic algorithms (GA) are used as solution approach. To validate the results obtained, they are compared with exhaustive search methods with higher computational cost proving that GA allow to find near-optimal solutions with less computational load. The proposed sensor placement algorithm is combined with a projection-based isolation scheme. However, the proposed methodology does not depend on the isolation method chosen by the user and it could be easily adapted to any other isolation scheme. Experiments on a real network allow to evaluate the performance of such approach. [less ▲]

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See detailOptimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms
Casillas, Myrna V.; Puig, Vicenç; Garza-Castañon, Luis E. et al

in Sensors (2013), 13(11), 14984-15005

This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization ... [more ▼]

This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach. [less ▲]

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See detailOptimal Sensor Placement for Leakage Detection and Isolation in Water Distribution Networks
Rosich, Albert UL; Sarrate, Ramon; Nejjari, Fatiha

in Fault Detection, Supervision and Safety of Technical Processes, Volume# 8 | Part# 1 (2012)

In this paper, the problem of leakage detection and isolation in water distribution networks is addressed applying an optimal sensor placement methodology. The chosen technique is based on structural ... [more ▼]

In this paper, the problem of leakage detection and isolation in water distribution networks is addressed applying an optimal sensor placement methodology. The chosen technique is based on structural models and thus it is suitable to handle non-linear and large scale systems. A drawback of this technique arises when costs are assigned uniformly. A main contribution of this paper is the proposal of an iterative methodology that focuses on identifying essential sensors which ultimately leads to an improvement of the optimal search efficiency. The algorithm presented in this work is successfully applied to a District Metered Area (DMA) in the Barcelona water distribution network. [less ▲]

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See detailOptimal Sensor Placement for Model-Based Fault Detection and Isolation
Sarrate, Ramon; Puig, Vicenç; Escobet, Teresa et al

in Decision and Control, 2007 46th IEEE Conference on (2007)

The problem of optimal sensor placement for FDI consists in determining the set of sensors that minimizes a pre-defined cost function satisfying at the same time a pre- established set of FDI ... [more ▼]

The problem of optimal sensor placement for FDI consists in determining the set of sensors that minimizes a pre-defined cost function satisfying at the same time a pre- established set of FDI specifications for a given set of faults. The main contribution of this paper is to propose an algorithm for model-based FDI sensor placement based on formulating a mixed integer optimization problem. FDI specifications are translated into constraints of the optimization problem considering that the whole set of ARRs has been generated, under the assumption that all candidate sensors are installed. To show the effectiveness of this approach, an application based on a two-tanks system is proposed. [less ▲]

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See detailThe optimal size of a permit market
Krysiak, Frank C.; Schweitzer, Patrick UL

in Journal of Environmental Economics and Management (2010), 60(2), 133-143

Regulating the emissions of non-uniformly mixed pollutants with a permit market carries the risk of hot spot formation, which can be reduced by dividing the regulation area into trading zones. The trading ... [more ▼]

Regulating the emissions of non-uniformly mixed pollutants with a permit market carries the risk of hot spot formation, which can be reduced by dividing the regulation area into trading zones. The trading zone approach has been extensively discussed for the full-information case. We consider incomplete information concerning the emitters’ abatement costs, their locations, and pollution dispersion. We derive the optimal number of trading zones and the optimal number of permits per zone and analyze under which conditions a system of independent trading zones is superior to other policy measures. Our results show that appropriately sized permit markets are well-suited to regulating non-uniformly mixed pollutants under informational constraints if firms are not too heterogeneous. Only for substantial heterogeneity and a highly non-linear damage function can it be optimal to use command-and-control strategies. [less ▲]

Detailed reference viewed: 123 (4 UL)
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See detailOptimal station localization for bicycle sharing system
Medard de Chardon, Cyrille UL

Scientific Conference (2013, September 07)

Many urban planning strategies for sustainable cities (New Urbanism, Mixed Use Development and Compact City) tout the need for smaller more compact communities [1, 2, 3]. These urban forms depend on a ... [more ▼]

Many urban planning strategies for sustainable cities (New Urbanism, Mixed Use Development and Compact City) tout the need for smaller more compact communities [1, 2, 3]. These urban forms depend on a modal shift from automobiles to walking and cycling. As this shift is unlikely to be driven by the markets, increases in sustainable modal transport, infrastructure and disincentives for driving [4] are necessary [5]. In some cities, bicycle sharing systems (BSS) have been catalysts for increasing cycling through their ability to extend existing public transit systems, encourage cycling accessibility and visibility. Cycling has many direct and indirect health benefits such as cardiovascular and reduced CO emissions, compared to car transport, respectively as well as social and equity benefits [6, 5:123]. BSSs are composed of bicycles and spatially fixed stations containing a constant number of docks. Two important advantages of the current generation BSSs are simplicity and security [7]; bicycle theft is difficult yet subscribers may checkout bicycles quickly and without difficulty, allowing users to seamlessly transfer between transport modes. The central question of this research is determining whether a mismatch occurs between BSS’s stations’ optimal locations based on origin and destination demands of potential cyclists and the existing stations. Most BSSs are being managed by private corporations, which often use advertising to subsidize the systems. BSS stations, or kiosks, often have double purposes of providing BSS services, such as checking out a bike, and displaying advertising. Effectively locating BSS stations throughout an urban fabric is of crucial importance to the adoption of the BSS. The optimal locations for advertising billboards and BSS stations are unlikely to consistently correspond. This conflict of interest has been explicitly anticipated by at least one city developing a BSS [8]. The overlap between optimal advertiser locations and stations for BSSs are destinations of high traffic such as commercial and transportation hubs. Conversely, BSS stations may insufficiently serve residential areas far from or without through-roads due to having decreased traffic and therefore marketing potential. This project addresses the question in three steps. The first is the gathering of spatial and spatio-temporal data related to cycling demand in order to develop demand surfaces. Next, demand is contrasted against existing BSS station infrastructure. Assessment is complex due to the alternate realities between data, theory and the practical operations of placing stations within available space constraints and the varying BSS priorities, such as social or racial equity, of cities. Finally we develop a model that optimally locates BSS stations for public use across the urban fabric based on demand and network distances between stations. Performing this process across multiple cities with BSSs we bring insight into whether a localization bias exists towards high throughput and advertising valued locations. Bicycle sharing systems may become the first new ubiquitous ‘public’ transport system in over a century. However, the initial privatization of this new transport system, whose impacts and evolution are not yet completely understood, may result in inefficiencies with lasting negative outcomes. The inadequate development of a city’s BSS may cause it to fail and stigmatize a progressive sustainable transport alternative for a generation. [less ▲]

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See detailOptimal strategy for multiple-phase estimation under practical measurement with multimode NOON states
Ur Rehman, Junaid UL; Hong, Seongjin; Lee, Seung-Woo et al

in Physical Review. A. (2022), 106

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See detailOptimal Switching from Competition to Cooperation: A Preliminary Exploration
Boucekkine, Raouf; Camacho, Carmen; Zou, Benteng UL

in Haunschmied, Josef; Kovacevic, Raimund; Semmler, Willi (Eds.) et al Dynamic economic problems with regime switches (2020)

In this paper, we tackle a generic optimal regime switching problem where the decision making process is not the same from a regime to another. Precisely, we consider a simple model of optimal switching ... [more ▼]

In this paper, we tackle a generic optimal regime switching problem where the decision making process is not the same from a regime to another. Precisely, we consider a simple model of optimal switching from competition to cooperation. To this end, we solve a twostage optimal control problem. In the first stage, two players engage in a dynamic game with a common state variable and one control for each player. We solve for open-loop strategies with a linear state equation and linear-quadratic payoffs. More importantly, the players may also consider the possibility to switch at finite time to a cooperative regime with the associated joint optimization of the sum of the individual payoffs. Using theoretical analysis and numerical exercises, we study the optimal switching strategy from competition to cooperation. We also discuss the reverse switching. [less ▲]

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See detailOptimal Timing of Carbon Capture and Storage Policies - a Social Planner's View
Chen, Yiwen; Wan, Xi; Zou, Benteng UL

E-print/Working paper (2022)

Carbon capture and storage (CCS) is considered one of the most realistic and plausible options for reducing greenhouse gas (GHG) emissions from large pollution sources. However, CCS deployment is costly ... [more ▼]

Carbon capture and storage (CCS) is considered one of the most realistic and plausible options for reducing greenhouse gas (GHG) emissions from large pollution sources. However, CCS deployment is costly. This paper considers the social cost of CCS projects and GHG damage from a central planer's point of view, providing clear information about when each player should deploy CCS. The findings are twofold: (1) given the heterogeneity of players, it is not socially optimal for all players to start CCS projects at the same time; instead, the player that has a cost advantage should start first; (2) it may be socially desirable for the player with a cost disadvantage never starts CCS. We show the conditions that support both possibilities. The second finding provides a clear policy guideline for the decision-maker: reduce the costs of the high-cost player in order to reduce global GHG emissions, provided that is the aim of the supranational institute. [less ▲]

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See detailOptimal TNFS-secure pairings on elliptic curves with composite embedding degree
Fotiadis, Georgios UL; Martindale, Chloe

E-print/Working paper (2019)

Detailed reference viewed: 110 (4 UL)
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See detailOptimal TNFS-secure pairings on elliptic curves with even embedding degree
Fotiadis, Georgios UL; Martindale, Chloe

E-print/Working paper (2018)

Detailed reference viewed: 70 (8 UL)