6,789 research outputs found
Pilot-optimal multivariable control synthesis by output feedback
A control system design approach for optimal stability augmentation, systems, using limited state feedback theory with the specific inclusion of the human pilot in the loop is presented. The methodology is especially suitable for application to flight vehicles exhibiting nonconventional dynamic characteristics and for which quantitative handling qualities specifications are not available. The design is based on a correlation between pilot ratings and objective function of the optimal control model of the human pilot. Simultaneous optimization for augmentation and pilot gains are required
Optimal cooperative control synthesis applied to a control-configured aircraft
A multivariable control augmentation synthesis method is presented that is intended to enable the designer to directly optimize pilot opinion rating of the augmented system. The approach involves the simultaneous solution for the augmentation and predicted pilot's compensation via optimal control techniques. The methodology is applied to the control law synthesis for a vehicle similar to the AFTI F16 control-configured aircraft. The resulting dynamics, expressed in terms of eigenstructure and time/frequency responses, are presented with analytical predictions of closed loop tracking performance, pilot compensation, and other predictors of pilot acceptance
Theoretical Zero Age Main Sequences revisited
Zero Age Main Sequence (ZAMS) models with updated physical inputs are
presented for selected assumptions about the chemical composition, covering the
ranges 0.6 < M/Mo < 1.2, 0.0001 < Z < 0.04, 0.23 < Y < 0.34.The HR diagram
location of the ZAMS as a function of Y and Z is discussed both in the
theoretical and in the observational HR diagrams, showing that the V magnitude
presents an increased dependence on Z to be taken into account when discussing
observational evidences. Analytical relations quantifying both these
dependences are derived. Implications for the galactic helium to heavier
elements enrichment are finally discussed.Comment: 4 pages, 4 postscript figures, accepted for publication on Astronomy
& Astrophysic
Gynecomastia and Chest Masculinization: An Updated Comprehensive Reconstructive Algorithm
Background: Gynecomastia is a common finding in males. Clinical aspect varies widely in world populations showing peculiar hallmarks according to different body shapes reflecting personal expectations; therefore, a surgical plan must be tailored on individual basis to all type of patients. Materials and Method: A total of 522 patients, treated for bilateral gynecomastia from January 2007 to January 2019, were included and reviewed in this retrospective study. Considering physical status BMI, muscular trophism, hypertrophy of the mammary region, nipple–areola disorder, gland and skin cover consistency, a four-tier classification system has been used to classify the deformity and to assess a surgical plan. In all cases, a subcutaneous mastectomy was performed under direct vision. Results: No recurrence of the deformity was observed as well as major complications such as necrosis, and high level of satisfaction was observed in all groups. No breast cancer was found at the histological examinations Operative time ranged from 25 minutes up to 120 minutes and hospitalization time ranged from 1 to 3 days. Conclusion: Since the physical status is strictly related to the clinical features of the disorder, a comprehensive classification system and a reconstructive algorithm are proposed. Level of Evidence IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/0026
A model for liquid-striped liquid phase separation in liquids of anisotropic polarons
The phase separation between a striped polaron liquid at the particular
density and a high density polaron liquid is described by a modified Van der
Waals scheme. The striped polaron liquid represents the pseudo gap matter or
Wigner-like polaron phase at 1/8 doping in cuprate superconductors. The model
includes the tendency of pseudo- Jahn-Teller polarons to form anisotropic
directional bonds at a preferential volume with the formation of different
liquid phases. The model gives the coexistence of a first low density polaron
striped liquid and a second high density liquid that appears in cuprate
superconductors for doping larger than 1/8. We discuss how the strength of
anisotropic bonds controls the variation the phase separation scenarios for
complex systems in the presence of a quantum critical point where the phase
separation vanishes.Comment: 10 pages, 3 figure
Assessing digital preservation frameworks: the approach of the SHAMAN project
How can we deliver infrastructure capable of supporting the
preservation of digital objects, as well as the services that can be applied to those digital objects, in ways that future unknown systems will understand? A critical problem in developing systems is the process of validating whether the delivered solution effectively reflects the validated requirements. This is a challenge also for the EU-funded SHAMAN project, which aims to develop an integrated preservation framework using grid-technologies for distributed networks of digital preservation systems, for managing the storage, access, presentation, and manipulation of digital objects over time. Recognising this, the project team ensured that alongside the user requirements an assessment framework was developed. This paper presents the assessment of the SHAMAN demonstrators for the memory institution, industrial design and engineering and eScience domains, from the point of view of
user’s needs and fitness for purpose. An innovative synergistic use of TRAC criteria, DRAMBORA risk registry and mitigation strategies, iRODS rules and information system models requirements has been designed, with the underlying goal to define associated policies, rules and state information, and make them wherever possible machine-encodable and enforceable. The described assessment framework can be valuable not only for the implementers of this project preservation framework, but for the wider digital preservation community, because it provides a
holistic approach to assessing and validating the preservation of digital libraries, digital repositories and data centres
Accelerometer-based navigation in total knee arthroplasty for the management of extra-articular deformity and retained femoral hardware: Analysis of component alignment
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