Variational approach for mechatronic tolerancing: application to a DC motor

2020 ◽  
Vol 21 (2) ◽  
pp. 206
Author(s):  
Hana Siala ◽  
Faïda Mhenni ◽  
Maher Barkallah ◽  
Jean-Yves Choley ◽  
Jamel Louati ◽  
...  
Keyword(s):  
Variational Approach ◽  
Dc Motor ◽  
Upper And Lower Bounds ◽  
Worst Case Analysis ◽  
System Quality ◽  
System Behavior ◽  
Mechatronic Systems ◽  
Worst Case ◽  
Target Values ◽  
The Impact

Having an increasingly complex set of inter-relations between several components from different domains, mechatronic systems become more and more complex. The behavior of such systems depends on the values of their parameters and variables. A deviation of these values from their expected values affects the overall functioning of the system, degrades the system quality, and may be a significant threat to safety. To reach an expected quality level, the deviations between actual and target values of parameters should be within specified tolerances. For this, two extreme limits (i.e. upper and lower bounds) of these values must be wisely determined. It is also important to know the impact of parameters deviations on system behavior. Furthermore, the margin of variables should be controlled to evaluate system performance with respect to the specifications, requirements and user needs. This paper describes a methodology based on a variational approach combined with Worst-Case Analysis and Monte Carlo Simulation to determine the impact of the parameters variation on the system behavior. It helps designers to analyze tolerances of mechatronic systems. Our proposed methodology is illustrated with a DC motor case study. The results show that the developed method provides a new way for mechatronic tolerancing.

A downward counter-factual climate risk analysis of the impact of tropical cyclones in the Caribbean islands

2020 ◽  
Author(s):  
Alessio Ciullo ◽  
Olivia Romppainen-Martius ◽  
Eric Strobl ◽  
David Bresch
Keyword(s):  
Risk Analysis ◽  
Tropical Cyclones ◽  
South Florida ◽  
Climate Risk ◽  
Worst Case Analysis ◽  
Worst Case ◽  
Analysis Study ◽  
Caribbean Islands ◽  
The Caribbean ◽  
The Impact

<p>Climate risk analysis and assessment studies are typically conducted relying on historical data. These data, however, represent just one single realization of the past, which could have unfolded differently. As an example, Hurricane Irma might had struck South Florida at Category 4 and, had it done so, damages could have been as high as 150 billion, about three times higher than damage estimated from the actual event. To explore the impacts of these potentially catastrophic near-misses, downward counter-factual risk analysis (Woo, Maynard and Seria, 2017) complements standard risk analysis by exploring alternative, plausible realization of past climatic events. As downward counter-factual risk analysis frames risk in an event-oriented manner, corresponding more closely to how people perceive risk, it is expected to increase climate risk awareness among people and policy makers (Shepherd et al., 2018).</p><p>We present a counter-factual risk analysis study of climate risk from tropical cyclones on the Caribbean islands. The analysis is conducted using the natcat impact model CLIMADA (Aznar-Siguan and Bresch, 2019). Impact is estimated based on forecasts of past tropical cyclones tracks from the THORPEX Interactive Grand Global Ensemble (TIGGE) dataset, as they all represent plausible alternative realizations of past tropical cyclones. The goal is to study whether, and to what extent, the estimated impacts from forecasts provide new insights than those provided by historical records in terms of e.g. cumulated annual damages, maximum annual damages and, in so doing, perform a worst-case analysis study to support climate risk management planning.</p><p><br>Aznar-Siguan, G. and Bresch, D. N.: CLIMADA v1: a global weather and climate risk assessment platform, Geosci. Model Dev., 12, 3085-3097, doi.org/10.5194/gmd-12-3085-2019, 2019.</p><p>Woo, G., Maynard, T., and Seria, J. Reimagining history. Counterfactual risk analysis. Retrieved from: https://www.lloyds.com/~/media/files/news-and-insight/risk-insight/2017/reimagining-history.pdf, 2017.</p><p>Shepherd, T.G., Boyd, E., Calel, R.A. et al.: Storylines: an alternative approach to representing uncertainty in physical aspects of climate change. Climatic Change 151, 555–571, doi.org/10.1007/s10584-018-2317-9 , 2018.</p>

Feasibility Analysis of Optical Wireless Communication for Indian Tropical and Subtropical Climates

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Gireesh Soni ◽  
Abhilash Mandloi ◽  
Shilpi Gupta
Keyword(s):  
Wireless Communication ◽  
Optical Radiation ◽  
Worst Case Analysis ◽  
Optical Wireless Communication ◽  
Optical Wireless ◽  
Worst Case ◽  
Communication Links ◽  
Recorded Data ◽  
High Precipitation ◽  
The Impact

AbstractThis work investigates the feasibility of terrestrial Optical wireless communication links under tropical and subtropical regions which are characterized by high precipitation. The impact of rain on propagating optical radiation is observed under controlled rainfall conditions using a laboratory testbed. Link degradation in terms of rain specific attenuation (RSA) is calculated experimentally and using known empirical models. A worst case analysis in terms of fade margin is carried out using measured and recorded data from Indian Meteorological Center to estimate the free space link feasibility for Indian tropical/subtropical climates.

scholarly journals Evaluation of OAR dose sparing and plan robustness of beam-specific PTV in lung cancer IMRT treatment

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Yu Chang ◽  
Feng Xiao ◽  
Hong Quan ◽  
Zhiyong Yang
Keyword(s):  
Lung Cancer ◽  
Intensity Modulated Radiotherapy ◽  
Incident Beam ◽  
Target Volume ◽  
Worst Case Analysis ◽  
Projection Area ◽  
Beam Direction ◽  
Worst Case ◽  
Lung Cancer Patients ◽  
The Impact

Abstract Purpose Margins are employed in radiotherapy treatment planning to mitigate the dosimetric effects of geometric uncertainties for the clinical target volume (CTV). Here, we proposed a margin concept that takes into consideration the beam direction, thereby generating a beam-specific planning target volume (BSPTV) on a beam entrance view. The total merged BSPTV was considered a target for optimization. We investigated the impact of this novel approach for lung intensity-modulated radiotherapy (IMRT) treatment, and compared the treatment plans generated using BSPTV with general PTV. Methods and materials We generated the BSPTV by expanding the CTV perpendicularly to the incident beam direction using the 2D version of van Herk’s margin concept. The BSPTV and general PTV margin were analyzed using digital phantom simulation. Fifteen lung cancer patients were used in the planning study. First, all patient targets were performed with the CTV projection area analysis to select the suitable beam angles. Then, BSPTV was generated according to the selected beam angles. IMRT plans were optimized with the general PTV and BSPTV as the target volumes, respectively. The dosimetry metrics were calculated and evaluated between these two plans. The plan robustness of both plans for setup uncertainties was evaluated using worst-case analysis. Results Both general PTV and BSPTV plans satisfied the CTV coverage. In addition, the BSPTV plans improved the sparing of high doses to target-surrounding lung tissues compared to the general PTV plans. Both Dmean of Ring PTV and Ring BSPTV were significantly lower in BSPTV plans (38.89 Gy and 39.43 Gy) compared to the general PTV plans (40.27 Gy and 40.68 Gy). The V20, V5, and mean lung dose of the affected lung were significant lower in BSPTV plans (16.20%, 28.75% and 8.93 Gy) compared to general PTV plans (16.69%, 29.22% and 9.18 Gy). In uncertainty scenarios, about 80% of target coverage was achieved for both general PTV and BSPTV plans. Conclusions The results suggested that plan robustness can be guaranteed in both the BSPTV and general PTV plans. However, the BSPTV plan spared normal tissues, such as the lungs, significantly better compared to the general PTV plans.

scholarly journals Evaluation of OAR sparing and plan robustness of beam-specific PTV in lung cancer IMRT treatment

2020 ◽  
Author(s):  
Yu Chang ◽  
Feng Xiao ◽  
Hong Quan ◽  
Zhiyong Yang
Keyword(s):  
Lung Cancer ◽  
Intensity Modulated Radiotherapy ◽  
Incident Beam ◽  
Target Volume ◽  
Worst Case Analysis ◽  
Projection Area ◽  
Beam Direction ◽  
Worst Case ◽  
Lung Cancer Patients ◽  
The Impact

Abstract Purpose: Margins are employed in radiotherapy treatment planning to mitigate the dosimetric effects of geometric uncertainties for the clinical target volume (CTV). Here, we proposed a margin concept that takes into consideration the beam direction, thereby generating a beam-specific planning target volume (BSPTV) on a beam entrance view. The total merged BSPTV was considered a target for optimization. We investigated the impact of this novel approach for lung intensity-modulated radiotherapy (IMRT) treatment, and compared the treatment plans generated using BSPTV with general PTV. Methods and Materials: We generated the BSPTV by expanding the CTV perpendicularly to the incident beam direction using the 2D version of van Herk’s margin concept. The BSPTV and general PTV margin were analyzed using digital phantom simulation. Fifteen lung cancer patients were used in the planning study. First, all patient targets were performed with the CTV projection area analysis to select the suitable beam angles. Then, BSPTV was generated according to the selected beam angles. IMRT plans were optimized with the general PTV and BSPTV as the target volumes, respectively. The dosimetry metrics were calculated and evaluated between these two plans. The plan robustness of both plans for setup uncertainties was evaluated using worst-case analysis. Results: Both general PTV and BSPTV plans satisfied the CTV coverage. In addition, the BSPTV plans improved the sparing of high doses to target-surrounding lung tissues compared to the general PTV plans. Both Dmean of Ring PTV and Ring BSPTV were significantly lower in BSPTV plans (38.89Gy and 39.43Gy) compared to the general PTV plans (40.27Gy and 40.68Gy). The V20, V5, and mean lung dose of the affected lung were significant lower in BSPTV plans (16.20%, 28.75% and 8.93Gy) compared to general PTV plans (16.69%, 29.22% and 9.18Gy). In uncertainty scenarios, about 80% of target coverage was achieved for both general PTV and BSPTV plans. Conclusions: The results suggested that plan robustness can be guaranteed in both the BSPTV and general PTV plans. However, the BSPTV plan spared normal tissues, such as the lungs, significantly better compared to the general PTV plans.

scholarly journals The Impact of Selfishness in Hypergraph Hedonic Games

2020 ◽  
Vol 34 (02) ◽  
pp. 1766-1773
Author(s):  
Alessandro Aloisio ◽  
Michele Flammini ◽  
Cosimo Vinci
Keyword(s):  
Social Welfare ◽  
Price Of Anarchy ◽  
Maximum Size ◽  
Upper And Lower Bounds ◽  
Worst Case ◽  
The Social ◽  
Worst Case Ratio ◽  
Distinct Node ◽  
Hedonic Games ◽  
The Impact

We consider a class of coalition formation games that can be succinctly represented by means of hypergraphs and properly generalizes symmetric additively separable hedonic games. More precisely, an instance of hypegraph hedonic game consists of a weighted hypergraph, in which each agent is associated to a distinct node and her utility for being in a given coalition is equal to the sum of the weights of all the hyperedges included in the coalition. We study the performance of stable outcomes in such games, investigating the degradation of their social welfare under two different metrics, the k-Nash price of anarchy and k-core price of anarchy, where k is the maximum size of a deviating coalition. Such prices are defined as the worst-case ratio between the optimal social welfare and the social welfare obtained when the agents reach an outcome satisfying the respective stability criteria. We provide asymptotically tight upper and lower bounds on the values of these metrics for several classes of hypergraph hedonic games, parametrized according to the integer k, the hypergraph arity r and the number of agents n. Furthermore, we show that the problem of computing the exact value of such prices for a given instance is computationally hard, even in case of non-negative hyperedge weights.

scholarly journals Evaluation of OAR sparing and plan robustness of beam-specific PTV in lung cancer IMRT treatment

2020 ◽  
Author(s):  
Yu Chang ◽  
Feng Xiao ◽  
Hong Quan ◽  
Zhiyong Yang
Keyword(s):  
Lung Cancer ◽  
Incident Beam ◽  
Target Volume ◽  
Worst Case Analysis ◽  
Projection Area ◽  
Beam Direction ◽  
Worst Case ◽  
Lung Cancer Patients ◽  
The Impact ◽  
Better Than

Abstract Purpose: Margins are employed in radiotherapy treatment planning to mitigate the dosimetric effects of geometric uncertainties for the clinical target volume (CTV). We propose a margin concept that takes the beam direction into consideration, generating a beam-specific PTV (BSPTV) on a beam entrance view. The total merged BSPTV was considered as target using for optimization. We investigated the impact of this novel approach when applied to lung IMRT treatments, and compared the treatment plans generated using BSPTV with conventional PTV. Methods and Materials: We margin the BSPTV by expanding the CTV perpendicularly to the incident beam direction using the 2D version of van Herk’s margin concept. The BSPTV and conventional PTV margin were first analyzed in digital phantom simulation. Then, fifteen lung cancer patients were used in this planning study. First, all patient targets were performed with the CTV projection area analysis to select the suitable beam angles. Then, BSPTV were margined according to the selected beam angles. IMRT plans were optimizted with the conventional PTV and BSPTV as the target volumes, respectively. The dosimetry metrics were calculated and evaluated between these two plans. The plan robustness of both plans for setup uncertainties was evaluated with worst-case analysis. Results: Both conventional PTV and BSPTV plans satisfied the CTV coverage. The BSPTV plans improved the sparing of high doses to target-surrounding lung tissues much better than the conventional PTV plans. Both Dmean of Ring PTV and Ring BSPTV were significantly lower in BSPTV plans (38.89Gy and 39.43Gy) than that in the conventional PTV plans (40.27Gy and 40.68Gy). The V20, V5 and mean lung dose of the affected lung were significant lower in BSPTV plans (16.20%, 28.75% and 8.93Gy) than that in the conventional PTV plans (16.69%, 29.22% and 9.18Gy). About 80% of target coverage in all uncertainty scenarios could be achieved for both conventional PTV and BSPTV plans. Conclusions: The results suggested that the plan robustness can be guaranteed in both the BSPTV and conventional PTV plans. However, the BSPTV plans can spare the normal tissues such as lungs significant better than the conventional PTV plans.

scholarly journals Adaptive Speed Control Design for Brushed Permanent Magnet DC Motor Based on Worst-Case Analysis Approach

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Sheng Zeng
Keyword(s):  
Control Problem ◽  
Permanent Magnet ◽  
Controller Design ◽  
Dc Motor ◽  
Robust Adaptive Control ◽  
Disturbance Attenuation ◽  
Worst Case Analysis ◽  
Theoretic Approach ◽  
Worst Case ◽  
Permanent Magnet Dc Motor

This paper presents the adaptive controller design for brushed permanent magnet DC motor used in velocity-tracking applications based on worst-case approach. We first formulate the robust adaptive control problem as a nonlinearH∞-control problem under imperfect state measurement, and then solve it using game-theoretic approach. The controller guarantees the boundedness of closed-loop signals with bounded exogenous disturbances, and achieves desired disturbance attenuation level with respect to the unmeasured exogenous disturbance inputs and the measured disturbance inputs. The strong robustness properties are illustrated by a simulation example.

scholarly journals Evaluation of OAR sparing and plan robustness of beam-specific PTV in lung cancer IMRT treatment

2020 ◽  
Author(s):  
Yu Chang ◽  
Feng Xiao ◽  
Hong Quan ◽  
Zhiyong Yang
Keyword(s):  
Lung Cancer ◽  
Incident Beam ◽  
Target Volume ◽  
Worst Case Analysis ◽  
Projection Area ◽  
Beam Direction ◽  
Worst Case ◽  
Lung Cancer Patients ◽  
The Impact ◽  
Better Than

Abstract Purpose: Margins are employed in radiotherapy treatment planning to mitigate the dosimetric effects of geometric uncertainties for the clinical target volume (CTV). We propose a margin concept that takes the beam direction into consideration, generating a beam-specific PTV (BSPTV) on a beam entrance view. The total merged BSPTV was considered as target using for optimization. We investigated the impact of this novel approach when applied to lung IMRT treatments, and compared the treatment plans generated using BSPTV with conventional PTV. Methods and Materials: We generated the BSPTV by expanding the CTV perpendicularly to the incident beam direction using the 2D version of van Herk’s margin concept. The BSPTV and conventional PTV margin were first analyzed in digital phantom simulation. Then, fifteen lung cancer patients were used in this planning study. First, all patient targets were performed with the CTV projection area analysis to select the suitable beam angles. Then, BSPTV were generated according to the selected beam angles. IMRT plans were optimizted with the conventional PTV and BSPTV as the target volumes, respectively. The dosimetry metrics were calculated and evaluated between these two plans. The plan robustness of both plans for setup uncertainties was evaluated with worst-case analysis. Results: Both conventional PTV and BSPTV plans satisfied the CTV coverage. The BSPTV plans improved the sparing of high doses to target-surrounding lung tissues much better than the conventional PTV plans. Both D mean of Ring PTV and Ring BSPTV were significantly lower in BSPTV plans (38.89Gy and 39.43Gy) than that in the conventional PTV plans (40.27Gy and 40.68Gy). The V20, V5 and mean lung dose of the affected lung were significant lower in BSPTV plans (16.20%, 28.75% and 8.93Gy) than that in the conventional PTV plans (16.69%, 29.22% and 9.18Gy). About 80% of target coverage in all uncertainty scenarios could be achieved for both conventional PTV and BSPTV plans. Conclusions: The results suggested that the plan robustness can be guaranteed in both the BSPTV and conventional PTV plans. However, the BSPTV plans can spare the normal tissues such as lungs significant better than the conventional PTV plans.

scholarly journals Reducing environmental impacts from garments through best practice garment use and care, using the example of a Merino wool sweater

2021 ◽  
Author(s):  
Stephen G. Wiedemann ◽  
Leo Biggs ◽  
Quan V. Nguyen ◽  
Simon J. Clarke ◽  
Kirsi Laitala ◽  
...  
Keyword(s):  
Environmental Impacts ◽  
Energy Demand ◽  
Best Practice ◽  
Western Europe ◽  
Impact Category ◽  
Fashion Industry ◽  
Worst Case ◽  
Multiple Users ◽  
Washing Machines ◽  
The Impact

Abstract Purpose Garment production and use generate substantial environmental impacts, and the care and use are key determinants of cradle-to-grave impacts. The present study investigated the potential to reduce environmental impacts by applying best practices for garment care combined with increased garment use. A wool sweater is used as an example because wool garments have particular attributes that favour reduced environmental impacts in the use phase. Methods A cradle-to-grave life cycle assessment (LCA) was used to compare six plausible best and worst-case practice scenarios for use and care of a wool sweater, relative to current practices. These focussed on options available to consumers to reduce impacts, including reduced washing frequency, use of more efficient washing machines, reduced use of machine clothing dryers, garment reuse by multiple users, and increasing number of garment wears before disposal. A sixth scenario combined all options. Worst practices took the worst plausible alternative for each option investigated. Impacts were reported per wear in Western Europe for climate change, fossil energy demand, water stress and freshwater consumption. Results and discussion Washing less frequently reduced impacts by between 4 and 20%, while using more efficient washing machines at capacity reduced impacts by 1 to 6%, depending on the impact category. Reduced use of machine dryer reduced impacts by < 5% across all indicators. Reusing garments by multiple users increased life span and reduced impacts by 25–28% across all indicators. Increasing wears from 109 to 400 per garment lifespan had the largest effect, decreasing impacts by 60% to 68% depending on the impact category. Best practice care, where garment use was maximised and care practices focussed on the minimum practical requirements, resulted in a ~ 75% reduction in impacts across all indicators. Unsurprisingly, worst-case scenarios increased impacts dramatically: using the garment once before disposal increased GHG impacts over 100 times. Conclusions Wool sweaters have potential for long life and low environmental impact in use, but there are substantial differences between the best, current and worst-case scenarios. Detailed information about garment care and lifespans is needed to understand and reduce environmental impacts. Opportunities exist for consumers to rapidly and dramatically reduce these impacts. The fashion industry can facilitate this through garment design and marketing that promotes and enables long wear life and minimal care.

Hierarchical Programming for Worst-Case Analysis of Power Grids

2018 ◽  
Author(s):  
Hatim Djelassi ◽  
Stephane Fliscounakis ◽  
Alexander Mitsos ◽  
Patrick Panciatici
Keyword(s):  
Case Analysis ◽  
Power Grids ◽  
Worst Case Analysis ◽  
Worst Case
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