Given a basic compact semialgebraic set ${\bf K}\subset {\Bbb R}^{n}$, we introduce a methodology that generates a sequence converging to the volume of K. This sequence is obtained from optimal ...values of a hierarchy of either semidefinite or linear programs. Not only the volume but also every finite vector of moments of the probability measure that is uniformly distributed on K can be approximated as closely as desired, which permits the approximation of the integral on K of any given polynomial; the extension to integration against some weight functions is also provided. Finally, some numerical issues associated with the algorithms involved are briefly discussed.
The aim of this paper is to introduce a new method for the solution of optimal control problems for which the system is composed by many subsystems whose dynamics are coupled through input–ouput ...connections. The proposed approach can be regarded as a generalization of the direct multiple shooting method and exploits the structure of the problem to achieve a highly parallelizable algorithm. To demonstrate its effectiveness, the new method is applied to the control of a hydro power plant composed of several connected reaches.
Abstract
Background
Sports motoring and racing imply high physical and psychological stress, during pre-competition phases and the competition itself. Therefore, there is growing interest of racing ...teams for new technologies providing real-time monitoring of psychophysiological reactions of pilots to highly-demanding driving and vehicle dynamics, to improve personalized training, while reducing human risks and costs.
Professional Driving Simulators (PDS) are ideal to assess in real-time vehicle dynamics under any kind of programmable virtual driving conditions, but a direct connection with the driver's physiology is still limited. A novel wearable system and software have been developed, providing simultaneous assessment of pilot's stress reactions, by real-time calculation and monitoring of time-variant heart rate variability (TV-HRV) spectral parameters (SP) and of skin potential response (SPR), in correlation with vehicle's dynamics.
Purpose
This study aimed to demonstrate the reliability of the method in detecting the pilot's stress induced by different driving demands.
Methods
10 volunteers (age 26±2.3 years) were enrolled to pilot a racing car under realistic conditions simulated by the DIM® PDS (Vi-grade). The study protocol consisted of 5-minutes baseline rest, sitting in the cockpit; 5-minutes driving along a straight highway without obstacles; 6-minutes of medium-stress slalom between cones, avoiding collision; 8-minutes racing 4 laps on a race track, at maximum possible speed, but avoiding crashes. ECG and SPR signals were acquired (1 Khz sample rate), with the Vi-BioBox connected to textile wearable sensors. A proprietary software was developed to analyze and stream the TV-HRV and SPR data in real-time to WINTAX4 data logging software for automotive racing industry. Real-time assessment of the pilot's stress was based on the integration of transient changes of HRV-SP and of the Root Mean Square value of two SPR signals (SPRRMS). To validate the accuracy of the real-time HRV analysis, all data were analyzed also off-line with Kubios Premium 3.4.1. software.
Results
The Vi-BioBox signals were adequate for real-time calculation and monitoring of transient variations of HRV-SP. A good correlation was found between transient stress-induced increment of pilots' SPRRMS values and the occurrence of driving errors (pink-red spots automatically transferred onto the race track – Figure 1). A good match was found between the real-time HRV values calculated by the VI-BioSoft and their off-line calculation with Kubios (v. 3.4.1 Premium). Two pilots, suffering simulator sickness, had prodromal alteration of cardiac autonomic modulation.
Conclusion
The integration of a Vi-grade PDS with the novel system for real-time calculation and telemetric monitoring of time-variant HRV and SPRRMS provides immediate information about pilot's autonomic response to driving demands and emotional reaction to vehicle's dysfunction, driving errors and bad performance.
Funding Acknowledgement
Type of funding sources: None. Figure 1
Abstract
Background
Although clinical assessment of cardiac autonomic modulation (CAM) usually relies on off-line heart rate variability analysis (HRVa), measured under stationary conditions ...according to guidelines, there is a growing interest, in sports medicine and psychophysiology, for the reliable evaluation of acute changes of CAM occurring under real-world dynamics (i.e. acute stress induced by competitions or critical situations). The aim of this study was to test, with a standardized clinical protocol inducing enhancement of sympathetic/vagal modulation, the reliability of a novel system for continuous monitoring and telemetric transmission of transient CAM changes, provided by real-time calculation of time-variant HRV parameters (HRVp) and Skin Potential Response (SPR).
Methods
All measurements were performed in the laboratory for clinical electrophysiology. The Vi-BioBox system consists of a wearable wireless mini-recording device connected to a textile electrode garment and hands electrodes. 3 ECG and 2 SPR signals are continuously recorded (1 kHz sampling-rate) and streamed in real-time to Wintax4 (Magneti-Marelli) data logging for real-time calculation and monitoring of spectral HRVp and of the Root Mean Square value of two SPR signals (SPRRMS) with a proprietary custom software. 10 healthy volunteers (mean age 32.4±16.8 y, 50% males) underwent a 5-steps protocol: 1) 10-minutes baseline supine; 2) 10-minutes Head-up tilting 70° (HUTT); 3) 10-minutes supine recovery); 4) 20-minutes mental stress (“Mensa” preliminary Tests); 5) exercise-test at bicycle-ergometer. 12-lead ECG was continuously recorded also with Mortara Surveyor/X-Scribe and Time-variant HRVp were also calculated off-line with Kubios (3.0.2) software. Statistical analysis was performed with SPSS 21.
Results
The quality of the Vi-BioBox signals was optimal for reproducible real-time calculation and monitoring of time-variant HRV parameters. Baseline SPRRMS activity ranged between 0.01 and 0.8 mV, with wide interindividual variability. A significant (p<0.05) increment (up to 2.6 mV) was induced by HUTT (example in Figure 1), but not by physical exercise. SPRRMS and LF/HF had similar trend along test session. Good agreement was found between HRVp calculated in real-time, their off-line recalculation with Kubios software and those obtained from Mortara telemetry.
Conclusion
Real-time monitoring of time-variant spectral HRVp and of SPRRMS was reliable and reproducible. SPRRMS is an independent sensitive marker of sympathetic activation, which anticipates increments of VLF, LF and is useful to interpret CAM underlying of LF/HF changes. Real-time monitoring of CAM may be useful to improve the mechanistic understanding of acute psychophysiological stress-reactions, dysautonomic syncope, arrhythmic events initiation and for telemedicine (i.e. continuous remote monitoring of CAM in patients with heart failure).
Figure 1. Real-time monitoring of HRV-SPR
Funding Acknowledgement
Type of funding source: None
Abstract
Background
Nowadays research on Autonomous Driving Systems (ADS) and attention towards novel technology allowing real-time assessment of car drivers' psycho-physiological status is growing, ...to quantify driver's stress during semi-autonomous or autonomous driving assistance and to investigate human reaction to different types of ADS. We present a system for automatic stress detection with combined machine learning analysis of Skin Potential Response (SPR) and electrocardiographic (ECG) recordings to compare the driver's stress reaction during both manual and autonomous driving sessions carried out in a dynamic professional drive simulator (PDS).
Methods
All data were acquired after informed consent from 14 healthy volunteers (HVs) in the Vi-grade (Udine) PDS. Two SPR signals (one from each hand) and three chest ECG leads were recorded. A Motion Artifact (MA) removal algorithm was used to remove motion artifacts from SPR signals. A cleaned, single SPR signal, obtained as the RMS value by combining the two original signals, was then sent together with the time-variation of heart rate (HR) to a Machine Learning (ML) classification algorithm, i.e., a Support Vector Machine (SVM), based on some specific features of this signal. The output of the SVM provides a series of labels, that indicate the presence or lack of stress episodes during the driving experiment. Stress occurrence was also independently quantified with heart rate variability (HRV) analysis in the time (TD) and frequency (FD) domains and with non-linear (NL) methods.
Results
All participants completed the driving protocol consisting of two subsequent sessions, one with conventional manual (MD) and the other with autonomous (AD) driving settings, along a highway where some unexpected events occurred, inducing different level stress response.
Figure 1 shows an example of time variant changes of the RMS SPR signal and of the HR of one tested individual during both experimental settings. A simultaneous increase of both SPR and HR signal is apparent during the stress episodes correctly identified by the SVM (gray shadows). Discriminant analysis of FD (VLF, LF and HF) and NL (SD1, SD2, Entropy and Recurrence Plot) HRV parameters, independently assessed by two researchers blind to SVM results, differentiated between stress induced by MD and AD (accuracy: 88,4% cross-correlated) in good agreement with automatic SVM assessment. In general stress level was lower during the AD, being all HRV parameters not significantly modified from baseline rest. SPR amplitude eventually increased also during AD, but SVM efficiently differentiated between AD and MD stress anyhow.
Conclusions
The proposed method for automatic assessment of stress reactions of car drivers with SVM of SPR and HR signals is reliable, in both MD and AD scenarios. The results seem to evidence that MD is in general more demanding than AD inducing higher activation of sympathetic nervous system, especially in critical situations.
Figure 1. Time variance of SPR and HR.
Funding Acknowledgement
Type of funding source: None
This paper proposes an algorithmic framework for solving parametric optimization problems which we call adjoint-based predictor-corrector sequential convex programming. After presenting the ...algorithm, we prove a contraction estimate that guarantees the tracking performance of the algorithm. Two variants of this algorithm are investigated. The first one can be used to solve nonlinear programming problems while the second variant is aimed to treat online parametric nonlinear programming problems. The local convergence of these variants is proved. An application to a large-scale benchmark problem that originates from nonlinear model predictive control of a hydro power plant is implemented to examine the performance of the algorithms.
In this paper the indoor wireless localization problem is addressed both from the theoretical and application standpoints. The main result of the paper is on the theoretical side: the topological ...definition of regular and irregular nodes is introduced, and formal results are presented to support regularity as a desirable network property for the attainment of precise node localization. In force of this definition, a mixed convex/non-convex optimization approach has been derived for the solution of the positioning problem. The two procedures, suitably combined, allow the achievement of better convergence towards the best positioning of a multitude of blind wireless nodes. A completely decentralized, partially asynchronous algorithm is presented, which proceeds locally on each node based on the sole knowledge of the distances measured from, and of the estimated positions of the connected nodes only. Its repeated asynchronous application on each nodes guarantees the convergence of the algorithm to the positioning of the whole network, even in presence of a limited number of peripheral reference points. Indeed, no global information is required for the proper functioning of the algorithm. Simulations of relevant case studies have been performed to qualify the proposed scheme in realistic conditions, and the results are presented.
ABSTRACT While spiral and lenticular galaxies have large-scale disks extending beyond their bulges, and most local early-type galaxies with 1010 < M*/M < 2 × 1011 contain a disk (e.g., ATLAS3D), the ...early-type galaxies do possess a range of disk sizes. The edge-on, intermediate-scale disk in the "disky elliptical" galaxy NGC 1271 has led to some uncertainty regarding its spheroidal component. Walsh et al. reported a directly measured black hole mass of for this galaxy, which they remarked was an order of magnitude greater than what they expected based on their derivation of the host spheroid's luminosity. Our near-infrared image analysis supports a small embedded disk within a massive spheroidal component with (using from Walsh et al.). This places NGC 1271 just 1.6 above the near-linear Mbh-Msph,* relation for early-type galaxies. Therefore, past speculation that there may be a systematic difference in the black hole scaling relations between compact massive early-type galaxies with intermediate-scale disks, i.e., ES galaxies such as NGC 1271, and early-type galaxies with either no substantial disk (E) or a large-scale disk (S0) is not strongly supported by NGC 1271. We additionally (1) show how ES galaxies fit naturally in the ("bulge"-to-total)-(morphological-type) diagram, while noting a complication with recent revisions to the Hubble-Jeans tuning-fork diagram, (2) caution about claims of over-massive black holes in other ES galaxies if incorrectly modeled as S0 galaxies, and (3) reveal that the compact massive spheroid in NGC 1271 has properties similar to bright bulges in other galaxies, which have grown larger-scale disks.
The transfusion of stored RBCs decreases nitric oxide bioavailability, which may have an adverse effect on vascular function. We assessed the effects of RBC transfusion on coronary vascular function ...by evaluating the relationship between myocardial oxygen delivery and demand as evidenced by ST segment variability.
Retrospective case-control study.
Nine-hundred seventy-three-bed pediatric hospital with a 54-bed cardiovascular ICU.
Seventy-three neonates with hypoplastic left heart syndrome following the Norwood procedure, 38 with a Blalock-Taussig shunt and 35 with a right ventricle to pulmonary artery shunt.
RBC transfusion.
High-frequency physiologic data were captured 30 minutes prior to the initiation of (baseline) and during the 120 minutes of the transfusion. A rate pressure product was calculated for each subject and used as an indicator of myocardial oxygen demand. Electrocardiogram leads (aVL, V1, II) were used to construct a 3D ST segment vector to assess ST segment variability and functioned as a surrogate indicator of myocardial ischemia. One-hundred thirty-eight transfusions occurred in the Blalock-Taussig shunt group and 139 in the right ventricle to pulmonary artery shunt group. There was no significant change in the rate pressure product for either group; however, ST segment variability progressively increased for the entire cohort during the transfusion, becoming statistically significant by the end of the transfusion. Upon subgroup analysis, this finding was noted with statistical significance in the Blalock-Taussig shunt group and trending toward significance in the right ventricle to pulmonary artery shunt group.
We found a significant increase in the ST segment variability and evidence of myocardial ischemia temporally associated with RBC transfusions in neonates following the Norwood procedure, specifically among those in the Blalock-Taussig shunt group, which may impact immediate and long-term outcomes.
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