Browsing by Subject "Recovery"

Now showing 1 - 9 of 9

Open Access
Dispersion of beliefs bounds: sentimental recovery
(Institute for Operations Research and the Management Sciences (INFORMS), 2024-02-19) Pazarbaşı, Altan; Schneider, Paul; Vilkov, Grigory
We present a nonparametric method to recover a bound on ex ante dispersion of beliefs (DBB) from asset prices with minimal assumptions. DBB constrains the dispersion among all possible distributions in an economy, consistent with observed prices and subject to a good -deal bound. In model -based economies, DBB effectively tracks belief heterogeneity and serves as a diagnostic tool for evaluating model calibrations. Empirically, DBB relates to common proxies of belief dispersion, offering a real-time, market -implied disagreement measure. Our versatile approach applies to both complete and incomplete markets represented by any asset class.
Open Access
Effect of spatial distribution of partial information on the accurate recovery of optical wave fields
(Optical Society of America, 2017) Oktem, F. S.; Özaktaş, Haldun M.
We consider the problem of recovering a signal from partial and redundant information distributed over two fractional Fourier domains. This corresponds to recovering a wave field from two planes perpendicular to the direction of propagation in a quadratic-phase multilens system. The distribution of the known information over the two planes has a significant effect on our ability to accurately recover the field. We observe that distributing the known samples more equally between the two planes, or increasing the distance between the planes in free space, generally makes the recovery more difficult. Spreading the known information uniformly over the planes, or acquiring additional samples to compensate for the redundant information, helps to improve the accuracy of the recovery. These results shed light onto redundancy and information relations among the given data for a broad class of systems of practical interest, and provide a deeper insight into the underlying mathematical problem.
Open Access
Flight network-based approach for integrated airline recovery with cruise speed control
(Institute for Operations Research and the Management Sciences (I N F O R M S), 2017) Arıkan, U.; Gürel, S.; Aktürk, M. S.
Airline schedules are generally tight and fragile to disruptions. Disruptions can have severe effects on existing aircraft routings, crew pairings, and passenger itineraries that lead to high delay and recovery costs. A recovery approach should integrate the recovery decisions for all entities (aircraft, crew, passengers) in the system as recovery decisions about an entity directly affect the others' schedules. Because of the size of airline flight networks and the requirement for quick recovery decisions, the integrated airline recovery problem is highly complex. In the past decade, an increasing effort has been made to integrate passenger and crew related recovery decisions with aircraft recovery decisions both in practice and in the literature. In this paper, we develop a new flight network based representation for the integrated airline recovery problem. Our approach is based on the flowof each aircraft, crewmember, and passenger through the flight network of the airline. The proposed network structure allows common recovery decisions such as departure delays, aircraft/crew rerouting, passenger reaccommodation, ticket cancellations, and flight cancellations. Furthermore, we can implement aircraft cruise speed (flight time) decisions on the flight network. For the integrated airline recovery problem defined over this network, we propose a conic quadratic mixed integer programming formulation that can be solved in reasonable CPU times for practical size instances. Moreover, we place a special emphasis on passenger recovery. In addition to aggregation and approximation methods, our model allows explicit modeling of passengers and evaluating a more realistic measure of passenger delay costs. Finally, we propose methods based on the proposed network representation to control the problem size and to deal with large airline networks. © 2017 INFORMS.
Open Access
Flora: a framework for decomposing software architecture to introduce local recovery
(John Wiley & Sons Ltd., 2009-07) Sözer, H.; Tekinerdoǧan, B.; Akşit, M.
The decomposition of software architecture into modular units is usually driven by the required quality concerns. In this paper we focus on the impact of local recovery concern on the decomposition of the software system. For achieving local recovery, the system needs to be decomposed into separate units that can be recovered in isolation. However, it appears that this required decomposition for recovery is usually not aligned with the decomposition based on functional concerns. Moreover, introducing local recovery to a software system, while preserving the existing decomposition, is not trivial and requires substantial development and maintenance effort. To reduce this effort we propose a framework that supports the decomposition and implementation of software architecture for local recovery. The framework provides reusable abstractions for defining recoverable units and the necessary coordination and communication protocols for recovery. We discuss our experiences in the application and evaluation of the framework for introducing local recovery to the open-source media player called MPlayer. Copyright 2009 John Wiley & Sons, Ltd.
Open Access
Force and time-dependent self-assembly, disruption and recovery of supramolecular peptide amphiphile nanofibers
(Institute of Physics Publishing, 2018) Dikecoglu, F. B.; Topal, A. E.; Ozkan A.D.; Tekin, E. D.; Tekinay, A. B.; Güler, Mustafa O.; Dana, A.
Biological feedback mechanisms exert precise control over the initiation and termination of molecular self-assembly in response to environmental stimuli, while minimizing the formation and propagation of defects through self-repair processes. Peptide amphiphile (PA) molecules can self-assemble at physiological conditions to form supramolecular nanostructures that structurally and functionally resemble the nanofibrous proteins of the extracellular matrix, and their ability to reconfigure themselves in response to external stimuli is crucial for the design of intelligent biomaterials systems. Here, we investigated real-time self-assembly, deformation, and recovery of PA nanofibers in aqueous solution by using a force-stabilizing double-pass scanning atomic force microscopy imaging method to disrupt the self-assembled peptide nanofibers in a force-dependent manner. We demonstrate that nanofiber damage occurs at tip-sample interaction forces exceeding 1 nN, and the damaged fibers subsequently recover when the tip pressure is reduced. Nanofiber ends occasionally fail to reconnect following breakage and continue to grow as two individual nanofibers. Energy minimization calculations of nanofibers with increasing cross-sectional ellipticity (corresponding to varying levels of tip-induced fiber deformation) support our observations, with high-ellipticity nanofibers exhibiting lower stability compared to their non-deformed counterparts. Consequently, tip-mediated mechanical forces can provide an effective means of altering nanofiber integrity and visualizing the self-recovery of PA assemblies.
Open Access
Lessons learned from experiencing Mavi At Café (Blue Horse Café) during six years : a qualitative analysis of factors contributing to recovery from the perspective of schizophrenia patients
(Turkish Association of Nervous and Mental Health, 2017) Soygür, Haldun; Yüksel, M. Merve; Eraslan, Pınar; Attepe Özden, Seda
Objective: In recent years, the recovery-oriented approaches (along with experiences and thoughts of patients and patient's relatives) have been taken into account for establishing mental health services and policies. This study aims to identify the factors contributing to recovery, as observed from the perspective of schizophrenia patients working at The Blue Horse Café which was founded by the Federation of Schizophrenia Associations. Method: The sample for the study consisted of 24 patients who worked at The Blue Horse Café. A phenomenological approach was used in the study, whereby interviews with patients were analyzed qualitatively. Results: Certain common factors, which were expressed as having contributed to recovery, were identified from the perspective of schizophrenia patients. These factors are: 1-The fact that the setting is informal and welcoming without being constrictive; 2-Predominance of the human element; 3-Hope and encouragement; 4-Being cared about; 5-Being able to reach someone when in need of support; 6-Friendly sharing; 7-Having a purpose, assuming responsibility, and being motivated; and 8-Giving meaning to life. Conclusion: The findings may serve as a stimulus since schizophrenia patients that contribute to recovery give mental health professionals the opportunity to question there need for a change in their professional roles. Additionally, schizophrenia patients that have experienced The Blue Horse Café draw attention to certain points and these points can serve as a guide, especially for establishing the working methods of Community Mental Health Centers.
Open Access
Piloted evaluation of a control allocation technique to recover from pilot-induced oscillations
(American Institute of Aeronautics and Astronautics, 2015) Acosta, D. M.; Yıldız, Yıldıray; Craun, R. W.; Beard, S. D.; Leonard, M. W.; Hardy, G. H.; Weinstein, M.
This paper describes the maturation of a control allocation technique designed to assist pilots in recovery from pilot-induced oscillations. The control allocation technique to recover from pilot-induced oscillations is designed to enable next-generation high-efficiency aircraft designs. Energy-efficient next-generation aircraft require feedback control strategies that will enable lowering the actuator rate limit requirements for optimal airframe design. A common issue on aircraft with actuator rate limitations is they are susceptible to pilot-induced oscillations caused by the phase lag between the pilot inputs and control surface response. The control allocation technique to recover from pilot-induced oscillations uses real-time optimization for control allocation to eliminate phase lag in the system caused by control surface rate limiting. System impacts of the control allocator were assessed through a piloted simulation evaluation of a nonlinear aircraft model in the NASA Ames Research Center's Vertical Motion Simulator. Results indicate that the control allocation technique to recover from pilot-induced oscillations helps reduce oscillatory behavior introduced by control surface rate limiting, including the pilot-induced oscillation tendencies reported by pilots.
Open Access
Recovery of sparse perturbations in Least Squares problems
(IEEE, 2011) Pilanci, M.; Arıkan, Orhan
We show that the exact recovery of sparse perturbations on the coefficient matrix in overdetermined Least Squares problems is possible for a large class of perturbation structures. The well established theory of Compressed Sensing enables us to prove that if the perturbation structure is sufficiently incoherent, then exact or stable recovery can be achieved using linear programming. We derive sufficiency conditions for both exact and stable recovery using known results of ℓ 0/ℓ 1 equivalence. However the problem turns out to be more complicated than the usual setting used in various sparse reconstruction problems. We propose and solve an optimization criterion and its convex relaxation to recover the perturbation and the solution to the Least Squares problem simultaneously. Then we demonstrate with numerical examples that the proposed method is able to recover the perturbation and the unknown exactly with high probability. The performance of the proposed technique is compared in blind identification of sparse multipath channels. © 2011 IEEE.
Open Access
Resource recovery management using inventory models and supply contracts: An application to leaded waste recovery
(International Society for Environmental Information Sciences, 2005) Gunalay, Y.; Yeomans J.S.
Several recent studies have shown that significant quantities of leaded wastes recovered from the disposal of television cathode ray tubes (CRTs) will be entering the waste stream over the next 50 years in a form that is ideal for post-consumer remanufacturing. Furthermore, numerous countries have recently enacted legislation requiring industrial systems to engage in the practice of industrial ecology by having all discarded, returned, or otherwise spent products from manufacturing processes become raw material inputs in subsequent manufacturing operations. Therefore legislation banning CRT disposal together with mandated remanufacturing requirements could lead to numerous potentially attractive business ventures for reprocessing and recycling the high lead content found in this waste. This paper examines inventory issues related to the effective management of these leaded CRT wastes and the nature of the waste flows is considered from the perspective of different management options for inventory control through the use of supply contracts. An effective inventory management policy is extremely important when there is great uncertainty and variability in the year-to-year or within-year quantity of product available - as is the case with the supply of CRT wastes. If it is anticipated that a high percentage of the waste stream will be utilized, then an effective inventory policy proves absolutely essential - but also proves to be an extremely complex process. Consequently, the supply contract approach can be employed to reconcile different pricing preferences with the varying delivery time horizons of different customers. © 2005 ISEIS - International Society for Environmental Information Sciences .