Dynamic Design Using the Kalman Filter for Flexible Systems With Epistemic Uncertainty

2015 ◽  
Author(s):  
Elham Keshavarzi ◽  
Matthew McIntire ◽  
Christopher Hoyle
Keyword(s):  
Kalman Filter ◽  
Epistemic Uncertainty ◽  
Time Frame ◽  
Flexible Systems ◽  
Dynamic Markets ◽  
Wide Range ◽  
Engineered Systems ◽  
Filter Approach ◽  
Reliability And Robustness ◽  
High Degree

Most engineered systems have to exhibit a high degree of reliability and robustness. They are high in cost and complexity and often incorporate highly sophisticated materials, components, design and other technologies. Therefore, they face uncertainties in categories ranging from technical issues to market changes. This includes a wide range of epistemic uncertainties, such as demand or budget uncertainty; due to increasingly dynamic markets it has become important for systems to cope with these uncertainties. In this paper, a Kalman filter approach is applied to control the design as uncertainties are resolved in a discrete time frame. It is shown how the Kalman filter approach treats the design as a stochastic control problem, in which the design is controlled throughout its lifecycle to compensate for sources of epistemic uncertainty, as the uncertainties are resolved. The proposed method is applicable to flexible systems where changing the design is possible. A design framework is proposed encompassing a set of definitions, metrics, the methodology, and a case study of a spaceborne system.

Investigation on the scattering characteristics and unsupervised clustering of 3D printed samples

2020 ◽  
Vol 12 (9) ◽  
pp. 862-869
Author(s):  
Mostafa Elsaadouny ◽  
Jan Barowski ◽  
Jochen Jebramcik ◽  
Ilona Rolfes
Keyword(s):  
Unsupervised Learning ◽  
Matched Filter ◽  
Median Filter ◽  
Image Interpretation ◽  
Radar Sensors ◽  
Learning Techniques ◽  
Wide Range ◽  
3D Printed ◽  
Filter Approach ◽  
High Degree

AbstractIn this work, the scattering characteristics of 3D-printed samples are being investigated by using a single-polarized and a cross-polarized radar system. The 3D-printed technology participates in a wide range of applications nowadays. The idea of synthetic aperture radar (SAR) has been utilized to investigate the reflected electromagnetic energy from the 3D-printed samples by setting each of the radar systems in a fixed position and the mounting sample on an x-y positioning table which has been used to achieve rectangular-scan mode for SAR. The data have been ported and processed by the matched filter approach. For better image interpretation, the data have been further processed by the median filter in order to reduce noise level while preserving the main image details. Afterwards, the data have been further investigated for determining and classifying any possible defects. This process has been accomplished by deploying the unsupervised learning concept to cluster the SAR responses into two groups, compromising the defected positions responses and the non-defected responses. The obtained results of both radar sensors have been compared and evaluated using different quality assessment factors. Moreover, unsupervised learning techniques have been investigated and the obtained results show a high degree of efficiency in clustering the SAR responses.

A dynamic design approach using the Kalman filter for uncertainty management

2017 ◽  
Vol 31 (2) ◽  
pp. 161-172 ◽  
Author(s):  
Elham Keshavarzi ◽  
Matthew McIntire ◽  
Christopher Hoyle
Keyword(s):  
Kalman Filter ◽  
Life Cycle ◽  
System Design ◽  
Satellite System ◽  
Life Cycles ◽  
Design Approach ◽  
Complex Engineered Systems ◽  
New States ◽  
Engineered Systems ◽  
Filter Approach

AbstractIt is desirable for complex engineered systems to be resilient to various sources of uncertainty throughout their life cycle. Such systems are high in cost and complexity, and often incorporate highly sophisticated materials, components, design, and other technologies. There are many uncertainties such systems will face throughout their life cycles due to changes in internal and external conditions, or states of interest, to the designer, such as technology readiness, market conditions, or system health. These states of interest affect the success of the system design with respect to the main objectives and application of the system, and are generally uncertain over the life cycle of the system. To address such uncertainties, we propose a resilient design approach for engineering systems. We utilize a Kalman filter approach to model the uncertain future states of interest. Then, based upon the modeled states, the optimal change in the design of the system is achieved to respond to the new states. This resilient method is applicable in systems when the ability to change is embedded in the system design. A design framework is proposed encompassing a set of definitions, metrics, and methodologies. A case study of a communication satellite system is presented to illustrate the features of the approach.

scholarly journals Generic SDE and GA-based workload modeling for cloud systems

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Cédric St-Onge ◽  
Souhila Benmakrelouf ◽  
Nadjia Kara ◽  
Hanine Tout ◽  
Claes Edstrom ◽  
...  
Keyword(s):  
Kalman Filter ◽  
User Behavior ◽  
Support Vector ◽  
Application Behavior ◽  
Load Fluctuation ◽  
Wide Range ◽  
Cloud Environments ◽  
High Degree ◽  
Workload Models

AbstractWorkload models are typically built based on user and application behavior in a system, limiting them to specific domains. Undoubtedly, such a practice creates a dilemma in a cloud computing (cloud) environment, where a wide range of heterogeneous applications are running and many users have access to these resources. The workload model in such an infrastructure must adapt to the evolution of the system configuration parameters, such as job load fluctuation. The aim of this work is to propose an approach that generates generic workload models (1) which are independent of user behavior and the applications running in the system, and can fit any workload domain and type, (2) model sharp workload variations that are most likely to appear in cloud environments, and (3) with high degree of fidelity with respect to observed data, within a short execution time. We propose two approaches for workload estimation, the first being a Hull-White and Genetic Algorithm (GA) combination, while the second is a Support Vector Regression (SVR) and Kalman-filter combination. Thorough experiments are conducted on real CPU and throughput datasets from virtualized IP Multimedia Subsystem (IMS), Web and cloud environments to study the efficiency of both propositions. The results show a higher accuracy for the Hull-White-GA approach with marginal overhead over the SVR-Kalman-Filter combination.

Understanding Conformational Entropy in Small Molecules

2020 ◽  
Author(s):  
Lucian Chan ◽  
Garrett Morris ◽  
Geoffrey Hutchison
Keyword(s):  
Small Molecules ◽  
Degrees Of Freedom ◽  
Absolute Error ◽  
Low Energy ◽  
Standard Entropy ◽  
Free Energies ◽  
Conformational Entropy ◽  
Wide Range ◽  
High Degree ◽  
Empirical Corrections

The calculation of the entropy of flexible molecules can be challenging, since the number of possible conformers grows exponentially with molecule size and many low-energy conformers may be thermally accessible. Different methods have been proposed to approximate the contribution of conformational entropy to the molecular standard entropy, including performing thermochemistry calculations with all possible stable conformations, and developing empirical corrections from experimental data. We have performed conformer sampling on over 120,000 small molecules generating some 12 million conformers, to develop models to predict conformational entropy across a wide range of molecules. Using insight into the nature of conformational disorder, our cross-validated physically-motivated statistical model can outperform common machine learning and deep learning methods, with a mean absolute error ≈4.8 J/mol•K, or under 0.4 kcal/mol at 300 K. Beyond predicting molecular entropies and free energies, the model implies a high degree of correlation between torsions in most molecules, often as- sumed to be independent. While individual dihedral rotations may have low energetic barriers, the shape and chemical functionality of most molecules necessarily correlate their torsional degrees of freedom, and hence restrict the number of low-energy conformations immensely. Our simple models capture these correlations, and advance our understanding of small molecule conformational entropy.

Cerebellotrigeminal Dermal Dysplasia (Gómez-López-Hernández Syndrome)

2018 ◽  
Vol 16 (05) ◽  
pp. 362-368 ◽  
Author(s):  
Federica Sullo ◽  
Agata Polizzi ◽  
Stefano Catanzaro ◽  
Selene Mantegna ◽  
Francesco Lacarrubba ◽  
...  
Keyword(s):  
De Novo ◽  
Chromosomal Rearrangements ◽  
Number Of Patients ◽  
Wide Range ◽  
Visual Problems ◽  
Neurodevelopmental Abnormalities ◽  
Clinical Triad ◽  
High Degree ◽  
Motor Handicap

Cerebellotrigeminal dermal (CTD) dysplasia is a rare neurocutaneous disorder characterized by a triad of symptoms: bilateral parieto-occipital alopecia, facial anesthesia in the trigeminal area, and rhombencephalosynapsis (RES), confirmed by cranial magnetic resonance imaging. CTD dysplasia is also known as Gómez-López-Hernández syndrome. So far, only 35 cases have been described with varying symptomatology. The etiology remains unknown. Either spontaneous dominant mutations or de novo chromosomal rearrangements have been proposed as possible explanations. In addition to its clinical triad of RES, parietal alopecia, and trigeminal anesthesia, CTD dysplasia is associated with a wide range of phenotypic and neurodevelopmental abnormalities.Treatment is symptomatic and includes physical rehabilitation, special education, dental care, and ocular protection against self-induced corneal trauma that causes ulcers and, later, corneal opacification. The prognosis is correlated to the mental development, motor handicap, corneal–facial anesthesia, and visual problems. Follow-up on a large number of patients with CTD dysplasia has never been reported and experience is limited to few cases to date. High degree of suspicion in a child presenting with characteristic alopecia and RES has a great importance in diagnosis of this syndrome.

scholarly journals Controlling Teleportation-Based Locomotion in Virtual Reality with Hand Gestures: A Comparative Evaluation of Two-Handed and One-Handed Techniques

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 715
Author(s):  
Alexander Schäfer ◽  
Gerd Reis ◽  
Didier Stricker
Keyword(s):  
Virtual Reality ◽  
Virtual Worlds ◽  
User Preferences ◽  
Interaction Techniques ◽  
Hand Gestures ◽  
Wide Range ◽  
Effectiveness And Efficiency ◽  
High Degree ◽  
Additional Hardware ◽  
Comprehensive Study

Virtual Reality (VR) technology offers users the possibility to immerse and freely navigate through virtual worlds. An important component for achieving a high degree of immersion in VR is locomotion. Often discussed in the literature, a natural and effective way of controlling locomotion is still a general problem which needs to be solved. Recently, VR headset manufacturers have been integrating more sensors, allowing hand or eye tracking without any additional required equipment. This enables a wide range of application scenarios with natural freehand interaction techniques where no additional hardware is required. This paper focuses on techniques to control teleportation-based locomotion with hand gestures, where users are able to move around in VR using their hands only. With the help of a comprehensive study involving 21 participants, four different techniques are evaluated. The effectiveness and efficiency as well as user preferences of the presented techniques are determined. Two two-handed and two one-handed techniques are evaluated, revealing that it is possible to move comfortable and effectively through virtual worlds with a single hand only.

scholarly journals Design of a high-stability heterogeneous clock system for small satellites in LEO

GPS Solutions ◽  
2021 ◽  
Vol 25 (3) ◽  
Author(s):  
Damon Van Buren ◽  
Penina Axelrad ◽  
Scott Palo
Keyword(s):  
Low Power ◽  
High Stability ◽  
Time Frame ◽  
System Stability ◽  
Small Satellite ◽  
Crystal Oscillator ◽  
Small Satellites ◽  
Clock System ◽  
Wide Range

AbstractWe describe our investigation into the performance of low-power heterogeneous timing systems for small satellites, using real GPS observables from the GRACE Follow-On mission. Small satellites have become capable platforms for a wide range of commercial, scientific and defense missions, but they are still unable to meet the needs of missions that require precise timing, on the order of a few nanoseconds. Improved low-power onboard clocks would make small satellites a viable option for even more missions, enabling radio aperture interferometry, improved radio occultation measurements, high altitude GPS navigation, and GPS augmentation missions, among others. One approach for providing improved small satellite timekeeping is to combine a heterogeneous group of oscillators, each of which provides the best stability over a different time frame. A hardware architecture that uses a single-crystal oscillator, one or more Chip Scale Atomic Clocks (CSACs) and the reference time from a GPS receiver is presented. The clocks each contribute stability over a subset of timeframes, resulting in excellent overall system stability for timeframes ranging from less than a second to several days. A Kalman filter is used to estimate the long-term errors of the CSACs based on the CSAC-GPS time difference, and the improved CSAC time is used to discipline the crystal oscillator, which provides the high-stability reference clock for the small satellite. Simulations using GRACE-FO observations show time error standard deviations for the system range from 2.3 ns down to 1.3 ns for the clock system, depending on how many CSACs are used. The results provide insight into the timing performance which could be achieved on small LEO spacecraft by a low power timing system.

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