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Signature characters of invariant Hermitian forms on irreducible Verma modules and Hall-Littlewood polynomials

MATHEMATISCHE ZEITSCHRIFT 2019年第1-2期292卷 267-305页

作者： Yee, Wai Ling Univ Windsor Dept Math & Stat Windsor ON Canada

The Unitary Dual Problem is one of mathematics' most important open problems: classify the irreducible unitary representations of a group. The general approach has been to classify all representations admitting non-degenerate invariant Hermitian forms, compute the signatures of those forms, and then determine which forms are positive definite. Signature character algorithms and formulas arising from deforming representations and analysing changes at reducibility points, as in Adams et al. (Unitary representations of real reductive groups (ArXiv e-prints), 2012) and Yee (Represent Theory 9:638-677, 2005), produce very complicated formulas or algorithms from the resulting recursion. This paper shows that in the case of irreducible Verma modules all of the complexity can be encapsulated by the affine Hecke algebra: for compact real forms and for alcoves corresponding to translations of the fundamental alcove by a regular weight, signature characters of irreducible Verma modules are in fact "negatives" of Hall-Littlewood polynomial summands evaluated at times a version of the Weyl denominator, establishing a simple signature character formula and drawing an important connection between signature characters and the affine Hecke algebra. Signature characters of irreducible highest weight modules are shown to be related to Kazhdan-Lusztig basis elements. This paper also handles noncompact real forms. The current state of the art for the unitary dual is a computer algorithm for determining if a given representation is unitary. These results suggest the potential to move the state of the art to a closed form classification for the entire unitary dual.

关键词： representations signatures state of the art Hermitian conjugate Irreducible computer algorithms Alcoves formula Unitary

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Virtual reality simulation of robotic transsphenoidal brain tumor resection: Evaluating dynamic motion scaling in a master-slave system

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INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND computer ASSISTED SURGERY 2019年第1期15卷 e1953-e1953页

作者： Heredia-Perez, Saul A. Harada, Kanako Padilla-Castaneda, Miguel A. Marques-Marinho, Murilo Marquez-Flores, Jorge A. Mitsuishi, Mamoru Univ Nacl Autonoma Mexico Appl Sci & Technol Inst Mexico City DF Mexico Univ Tokyo Sch Engn Dept Mech Engn Tokyo Japan

Background Integrating simulators with robotic surgical procedures could assist in designing and testing of novel robotic control algorithms and further enhance patient-specific pre-operative planning and training for robotic surgeries. Methods A virtual reality simulator, developed to perform the transsphenoidal resection of pituitary gland tumours, tested the usability of robotic interfaces and control algorithms. It used position-based dynamics to allow soft-tissue deformation and resection with haptic feedback;dynamic motion scaling control was also incorporated into the simulator. Results Neurosurgeons and residents performed the surgery under constant and dynamic motion scaling conditions (CMS vs DMS). DMS increased dexterity and reduced the risk of damage to healthy brain tissue. Post-experimental questionnaires indicated that the system was well-evaluated by experts. Conclusion The simulator was intuitively and realistically operated. It increased the safety and accuracy of the procedure without affecting intervention time. Future research can investigate incorporating this simulation into a real micro-surgical robotic system.

关键词： brain tissue Brain Neoplasms virtual reality Scaling control master-slave system ectomy simulator dexterity cancer surgery Surgery computer algorithms

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Experimental Optimal Choice Of Initial Candidate Inliers Of The Feature Pairs With Well-Ordering Property For The Sample Consensus Method In The Stitching Of Drone-based Aerial Images

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KSII TRANSACTIONS ON INTERNET AND INFORMATION SYSTEMS 2020年第4期14卷 1648-1672页

作者： Shin, Byeong-Chun Seo, Jeong-Kweon Chonnam Natl Univ Dept Math Gwangju South Korea

There are several types of image registration in the sense of stitching separated images that overlap each other. One of these is feature-based registration by a common feature descriptor. In this study, we generate a mosaic of images using feature-based registration for drone aerial images. As a feature descriptor, we apply the scale-invariant feature transform descriptor. In order to investigate the authenticity of the feature points and to have the mapping function, we employ the sample consensus method;we consider the sensed image's inherent characteristic such as the geometric congruence between the feature points of the images to propose a novel hypothesis estimation of the mapping function of the stitching via some optimally chosen initial candidate inliers in the sample consensus method. Based on the experimental results, we show the efficiency of the proposed method compared with benchmark methodologies of random sampling consensus method (RANSAC);the well-ordering property defined in the context and the extensive stitching examples have supported the utility. Moreover, the sample consensus scheme proposed in this study is uncomplicated and robust, and some fatal miss stitching by RANSAC is remarkably reduced in the measure of the pixel difference.

关键词： computer algorithms Scale-invariant feature transform Feature matching Stitching images Drone-based aerial image

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computerized algorithms compared with a nephrologist's diagnosis of acute kidney injury in the emergency department

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EUROPEAN JOURNAL OF INTERNAL MEDICINE 2019年 60卷 78-82页

作者： Jonsson, Arnar Jan Kristjansdottir, Ingibjorg Lund, Sigrun Helga Palsson, Runolfur Indridason, Olafur S. Univ Iceland Reykjavik Iceland Landspitali Natl Univ Hosp Iceland Internal Med Serv Reykjavik Iceland Landspitali Natl Univ Hosp Iceland Div Nephrol Off 11-H IS-101 Reykjavik Iceland

Background: The aim of this study was to examine acute kidney injury (AKI) diagnosis based on different computerized algorithms compared with a nephrologists diagnosis in patients visiting an emergency department (ED) of a university hospital. Methods: In this retrospective study, we used electronic medical records at the University Hospital in Reykjavik to identify all patients aged >= 18 years, who presented to the ED in the year 2010 with an elevated serum creatinine (SCr) level. All SCr values were reviewed and a nephrologist determined whether AKI was present using the KDIGO SCr criteria and clinical data. computerized algorithms based on the KDIGO SCr criteria, accounting for various time intervals for baseline SCr and changes in follow-up SCr, were constructed using the statiscal software R. Results: At 53,816 ED visits, SCr was measured in 15,588 patients for a total of 21,559 measurements. Elevated SCr was observed in 2878 (18.4%) patients. Strict adherence to the KDIGO SCr criteria yielded a 79% sensitivity, 94% specificity, 68% positive predictive value (PPV) and 96% negative predictive value (NPV) for the diagnosis of AKI. Allowing for a longer time frame (> 365 days) for baseline SCr, resulted in 93% sensitivity, 96% specificity, 80% PPV and 99% NPV. The algorithms which included a decrease in SCr from the index ED value yielded a sensitivity of 97% but lower specificity, 74% and 80%. Conclusions: The algorithms that perform best yield excellent sensitivity and specificity and could be used to identify patients with AKI in the ED to enhance early diagnosis and treatment.

关键词： Acute kidney injury Serum creatinine Diagnosis computer algorithms KDIGO criteria

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Shift, rotation and scale invariant optical fingerprint verification system with double random phase encoding

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JOURNAL OF ENGINEERING-JOE 2020年第13期2020卷 476-481页

作者： Zhuo, Shengkai Jiao, Shuming Zou, Wenbin Wang, Na Li, Xia Shenzhen Univ Coll Elect & Informat Engn Guangdong Prov Key Lab Intelligent Informat Proc Shenzhen Peoples R China Shenzhen Univ Shenzhen Key Lab Adv Machine Learning & Applicat Shenzhen Peoples R China Shenzhen Univ Coll Optoelect Engn Nanophoton Res Ctr Shenzhen Peoples R China

Biometric features such as fingerprint images can be authenticated by not only computer algorithms but also optical systems. In previous works, double random phase encoding (DRPE) optical lens system is employed for fingerprint verification. However, such a system can yield authentication failure when the key is generated from a slightly distorted fingerprint image. In this work, a fingerprint image pre-processing scheme for DRPE fingerprint optical authentication system is proposed. Simulated experimental results demonstrate the proposed method has significantly better robustness to shift, rotation and scale variance than some of the conventional DRPE-based approaches.

关键词： encoding fingerprint identification image coding cryptography biometrics (access control) scale variance DRPE fingerprint optical authentication system fingerprint image pre-processing scheme slightly distorted fingerprint image authentication failure double random phase encoding optical lens system optical systems computer algorithms fingerprint images biometric features scale invariant optical fingerprint verification system

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Utilizing Mobile Nodes for Congestion Control in Wireless Sensor Networks 30

Utilizing Mobile Nodes for Congestion Control in Wireless Se...

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30th IEEE Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Nicolaou, Antonia Temene, Natalie Sergiou, Charalampos Georgiou, Chryssis Vassiliou, Vasos Univ Cyprus Dept Comp Sci Nicosia Cyprus RISE Res Ctr Interact Media Smart Syst & Emerging Nicosia Cyprus

ISBN: (纸本)9781538681107

Congestion control and avoidance in Wireless Sensor Networks (WSNs) is a subject that has attracted a lot of research attention in the last decade. Besides rate and resource control, the utilization of mobile nodes has also been suggested as a way to control congestion. In this work, we present a Mobile Congestion Control (MobileCC) algorithm with two variations, to assist existing congestion control algorithms in facing congestion in WSNs. The first variation employs mobile nodes that create locally-significant alternative paths leading to the sink. The second variation employs mobile nodes that create completely individual (disjoint) paths to the sink. Simulation results show that both variations can significantly contribute to the alleviation of congestion in WSNs.

关键词： Wireless sensor networks Mobile nodes computer algorithms Sinks EMPLOYMENT Standing Orders Paths first variation Avoidance

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Safe Spacecraft Rendezvous Using Dual Quaternions on Time-Dependent Trajectories Generated by Model Predictive Control

Safe Spacecraft Rendezvous Using Dual Quaternions on Time-De...

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AIAA Science and Technology (SciTech) Forum and Exposition

作者： Buyukkocak, Ali Tevfik Tekinalp, Ozan Middle East Tech Univ Dept Aerosp Engn TR-06800 Ankara Turkey

ISBN: (数字)9781624105784

ISBN: (纸本)9781624105784

Rendezvous and docking (R-D) problem of a pair of low Earth orbit spacecraft is addressed. Two different sets of equations for the nonlinear orbital relative motion of spacecraft are derived, and simulation codes for this motion are developed. First, Hill-Clohessy-Wiltshire (HCW) equations are used in chaser-target spacecraft configuration with Model Predictive Control (MPC) algorithm including several safety considerations such as debris avoidance, approach direction constraint and slow impact requirement. The HCW equations are linearized assuming a circular orbit. All authority is given to the chaser spacecraft, and the target is kept passive. The safe trajectory generated by MPC approach is also tracked by a novel Lyapunov based control algorithm. The algorithm is based on dual quaternions for the motion parametrization and provides a combined control of both translational and rotational motions. An error dual quaternion and its derivative are found from desired attitude and position information. As desired attitude trajectory is a time-dependent polynomial function, position trajectory is retrieved from MPC solution directly. Two control approaches are compared. Simulation results are given and discussed.

关键词： Quaternion Spacecraft trajectory SPACE RENDEZVOUS Model predictive control combined control Predictive control Maximum Allowable Concentration distributed model predictive control nonlinear model predictive control computer algorithms Dual

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Experimental Results with the Set-Theoretic Model Reference Adaptive Control Architecture on an Aerospace Testbed

Experimental Results with the Set-Theoretic Model Reference ...

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AIAA Science and Technology (SciTech) Forum and Exposition

作者： Arabi, Ehsan Yucelen, Tansel Univ S Florida Dept Mech Engn Tampa FL 33620 USA Univ S Florida Lab Auton Control Informat & Syst LACIS Tampa FL 33620 USA Missouri Univ Sci & Technol Dept Mech & Aerosp Engn Rolla MO 65409 USA Amer Inst Aeronaut & Astronaut Reston VA USA Natl Acad Inventors Tampa FL USA

ISBN: (数字)9781624105784

ISBN: (纸本)9781624105784

In this paper, we present experimental results of a recently developed set-theoretic model reference adaptive control architecture on an aerospace testbed, which is configured as a conventional dual-rotor helicopter. The key feature of this architecture allows the system error bound between the state of an uncertain dynamical system and the state of a reference model, which captures a desired closed-loop system performance, to be less than a-priori, user-defined worst-case performance bound. This means that this proposed architecture is suitable for enforcing strict performance guarantees during the transient and steady-state response of the adaptation process. Specifically, we first experimentally demonstrate the practical capabilities of this adaptive control algorithm with constant performance bounds on the considered testbed. We then consider the time-varying performance bounds, where we highlight how a control designer is empowered by the set-theoretic model reference adaptive control architecture to control the closed-loop system performance as desired on different time intervals (e.g. transient time interval and steady-state time interval) and also how to handle a possible system initialization error that can happen in practice.

关键词： Control Architecture model reference adaptive control Building construction ARCHITECTURE Systematic errors Time intervals reference model System performance aerospace Bound computer algorithms

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Dynamics and Estimation of Origami-Inspired Deployable Space Structures: A Review

Dynamics and Estimation of Origami-Inspired Deployable Space...

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AIAA Science and Technology (SciTech) Forum and Exposition

作者： McPherson, Brandi N. Kauffman, Jeffrey L. Univ Cent Florida Mech & Aerosp Engn Dept Orlando FL 32816 USA

ISBN: (数字)9781624105784

ISBN: (纸本)9781624105784

Large precision deployable structures are an increasingly popular solution to the challenges posed by deep space missions. Deployable structures, such as booms or solar arrays, are packaged to satisfy launch vehicle storage constraints and optimized for later deployment in orbit. The majority of literature in the field of deployables investigates structural design and the kinematics associated with unique packaging techniques such as origami. However, to increase reliability of such structures for implementation into future missions, the complex nonlinear dynamics of deployment should be further investigated. Additionally, more accurate on-orbit shape and dynamics estimation methods are needed for implementation into control algorithms and overall monitoring of the structure. The primary goal of this paper is to review current work in the field of deployable structure dynamics and prediction, with a special interest in origami-inspired engineering. Areas for future work are identified through gaps in the literature, and possible solutions for current deployable structure challenges are presented.

关键词： dynamics Solar cell arrays BOOMS deployment Nonlinear Dynamics computer algorithms Structural design Religious Missions Literature Packaging Fields kinematics

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Achieving Fairness in the Tangle through an Adaptive Rate Control Algorithm 1

Achieving Fairness in the Tangle through an Adaptive Rate Co...

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1st IEEE International Conference on Blockchain and Cryptocurrency (IEEE ICBC)

作者： Vigneri, Luigi Welz, Wolfgang Gal, Alon Dimitrov, Vassil IOTA Fdn D-10405 Berlin Germany

ISBN: (纸本)9781728113289

Throughput is a key property for any distributed ledger technology. However, limited resources, such as bandwidth or node computational power, can lead to network congestion when nodes try to issue more transactions than the network can handle. Consequently, priority criteria are necessary to determine whether a transaction should be accepted or not. In this paper, we present a novel adaptive rate control algorithm for the Tangle, a new-generation distributed ledger allowing large throughput. Our approach combines various concepts, such as resource tests and Proof-of-Work with dynamic difficulty. Our algorithm not only serves as an anti-spam mechanism, but also achieves fair representation. This is to be contrasted with pure Proof-of-Work blockchains, which lead to wasteful mining races.

关键词： cryptocurrencies financial data processing Financial data processing computer algorithms rate adaptive tangling Throughput Network Congestion

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