Autonomic Power Research Articles

Orthostatic intolerance after acute mild hypovolemia: incidence, pathophysiologic hemodynamics, and heart-rate variability analysis—a prospective observational cohort study

PurposeEarly postoperative mobilization can be hindered by orthostatic intolerance (OI). Postoperative OI has multifactorial pathogenesis, possibly involving both postoperative hypovolemia and autonomic dysfunction. We aimed to investigate the effect of mild acute blood loss from blood donation simulating postoperative hypovolemia, on both autonomic function and OI, thus eliminating confounding perioperative factors such as inflammation, residual anesthesia, pain, and opioids.MethodsThis prospective observational cohort study included 26 blood donors. Continuous electrocardiogram data were collected during mobilization and night sleep, both before and after blood donation. A Valsalva maneuver and a standardized mobilization procedure were performed immediately before and after blood donation, during which cardiovascular and tissue oxygenation variables were continuously measured by LiDCOrapid™ and Massimo Root™, respectively. The incidence of OI, hemodynamic responses during mobilization and Valsalva maneuver, as well as heart rate variability (HRV) responses during mobilization and sleep were compared before and 15 min after blood donation.ResultsPrior to blood donation, no donors experienced OI during mobilization. After blood donation, 6/26 (23%; 95% CI, 9 to 44) donors experienced at least one OI symptom. Three out of 26 donors (12%; 95% CI, 2 to 30) terminated the mobilization procedure prematurely because of severe OI symptoms. Cardiovascular and cerebral tissue oxygenation responses were reduced in patients with severe OI. After blood loss, HRV indices of total autonomic power remained unchanged but increased sympathetic and decreased parasympathetic outflow was observed during mobilization, but also during sleep, indicating a prolonged autonomic effect of hypovolemia.ConclusionWe describe a specific hypovolemic component of postoperative OI, independent of postoperative autonomic dysfunction, inflammation, opioids, and pain.Study registrationClinicalTrials.gov (NCT04499664); registered 5 August 2020.

Spectral analysis of cardiovascular oscillations in the 7-day regimen of losartan administration with and without cold stress.

Spectral analysis of heart rate (HR) and blood pressure (BP) variabilities (BPV and HRV) is widely available and utilized in understanding the dynamic cardiovascular autonomic regulation in a variety of pathophysiological conditions. In conscious cold-stressed (CS) rats, we examined the effect of a 7-day regimen administration of losartan, a selective nonpeptide angiotensin AT1 receptor blockade, on BPV and HRV at three frequency components: very-low frequency (VLF), low frequency (LF), and high frequency (HF). Key findings in changes of systolic BP (SBP), HR, and spectral power densities for cardiopulmonary oscillations (HF), sympathetic oscillations (LF), cardiovascular myogenic oscillations (VLF), and overall autonomic activity total power (TP) showed: (I) In the resting PreCS trial, compared with the saline, losartan increased HFBPV, TPHRV, all three HRV frequency powers, and the occurrence of the dicrotic notch (DN). However, it decreased SBP, HR, and the LFBPV frequency power. (II) In the CS trial, losartan significantly decreased SBP and DN occurrence and HR and LF/HFHRV but significantly increased HFHRV, TPBPV, and all three BPV frequency powers. In addition, similar to the saline, losartan showed positively correlated LFBPV and VLFBPV. Conversely, losartan converted the original inverse correlations between LFHRV and LFBPV of CS to a positive correlation. (III) Compared with saline in PreCS and CS trials, losartan detached the corresponding sympathetic oscillations between LFBPV and LFHRV. The overall result indicates that endogenous angiotensin II, through stimulation of the AT1 receptor, augments sympathetic tone but attenuates sympathetic oscillations in rats, particularly under the stressful cooling impacts.

Normative data on cardiovascular autonomic function in Greenlandic Inuit

IntroductionDiabetes is increasing among Greenlandic Inuit; however, the prevalence of cardiovascular autonomic neuropathy (CAN) is yet unknown. The assessment of CAN requires an ability to differentiate between normal and abnormal....

Derating of an Induction Machine under Voltage and Frequency Deviation

One of the most frequently appearing power quality disturbances is voltage deviation. In addition in autonomic power systems, e.g. in ships, frequency deviation often occurs. It causes additional power losses and increase in thermal loads of induction machines. This paper deals with an effect of voltage and frequency deviation on derating.

The Spectrum of Autonomic Dysfunction in Myasthenic Crisis.

Background:Autoimmune autonomic dysfunction is described in Myasthenia Gravis. In myasthenic crisis, the spectrum of autonomic dysfunction is hitherto uncharacterized.Objective:The objective of this study is to describe the spectrum of autonomic dysfunction in myasthenic crises using the composite autonomic symptom scale 31 (COMPASS 31) autonomic symptom questionnaire and power spectral analysis of heart rate variability (HRV), which is a simple way of estimating general autonomic dysfunction.Methods:Adult patients with myasthenic crisis from January 1, 2014 to March 15, 2015, were prospectively included in this study. The COMPASS 31 questionnaire for symptoms of autonomic dysfunction and power spectral analysis of HRV were assessed. These were compared with the patient's demographic and clinical parameters and with previous literature. IRB approval was obtained.Results:Sixteen patients were included (M:F 3:1). 15/16 patents (93%) had autonomic dysfunction on COMPASS 31 questionnaire. The domains of involvement were gastrointestinal (80%), orthostatic (67.7%), pupillomotor (67.7%); sudomotor (33.3%), and vasomotor (13.3%). Parasympathetic dysfunction predominance was suggested by the symptom profile. HRV analysis showed a low frequency (LF) spectral shift suggesting slowed parasympathetic responsiveness (LF normalized unit (nu): high frequency [HF] nu mean 8.35, standard deviation ± 5.4, 95% confidence interval 2.2–12.5), which significantly exceeded the mean LF nu: HF nu ratios of the majority of previously reported noncrises myasthenic populations.Conclusions:Myasthenic crisis has autonomic dysfunction involving multiple organ systems. Increased latency of parasympathetic reflexes is suggested. A comprehensive management protocol addressing different autonomic domains is required for holistic patient care.

The Study of Permanent Magnets Synchronous Machine (PMSM) of the Autonomous Electric Power Supply System (ASE), compatible with the Concept of a More Electric Aircraft (MEA)

Based on the analysis and mathematical models of synchronous electric machines (motor/generator), basing on permanent magnets, presented in this paper, the main importance of alternator AC power sources in the form of starter/generator (for conventional aircraft) and in the form of integrated unit starter (motor)/AC synchronous generator S/G AC (with respect to advanced aircraft concept in terms of more electric aircraft) was highlighted. Additionally, through the analysis and selected simulations of the on-board autonomous power supply system of the modern aircrafts, sources of electrical energy (synchronous motor/generator, integrated unit starter/AC generator) were located in board autonomic power system ASE (EPS, PES). Main components of this system are the electro-energetic power system EPS and the energo-electronic power system PES. In addition, the analysis and exemplary simulations of main electricity sources based on mathematical models have contributed to highlighting the main practical applications in accordance with the concept of MEA.

PERSONALIZED EXERCISE TRAINING PROGRAM AS A COUNTERMEASURE TO ORTHOSTATIC INTOLERANCE AFTER SPACE FLIGHTS.

PERSONALIZED EXERCISE TRAINING PROGRAM AS A COUNTERMEASURE TO ORTHOSTATIC INTOLERANCE AFTER SPACE FLIGHTS.

Model and Simulation of Permanent Magnets Synchronous Machine (PMSM) of the Electric Power Supply System (EPS), in Accordance with the Concept of a More Electric Aircraft (MEA)

Based on the mathematical model of synchronous electric machine, basing on permanent magnets, presented in this paper, the key importance of alternator AC power sources in the form of generator (for conventional aircraft) and in the form of integrated unit starter/AC synchronous generator S/G AC (with respect to advanced aircraft concept in the field of more/all electric power MEA/AEA) was highlighted. In addition, through the analysis and selected simulations of the power supply system of a modern aircrafts, sources of onboard electrical energy (synchronous generator, integrated unit starter/AC generator) were located in board autonomic power system ASE (EPS, PES). Key components of this system are the electro-energetic power system EPS and the energo-electronic power system PES. Additionally, the analysis and exemplary simulations of key electricity sources based on mathematical models have contributed to highlighting the main practical applications in line with the trend of a more electric aircraft.

Challenges, innovative architectures and control strategies for future networks: the Web-of-Cells, fractal grids and other concepts

The large-scale deployment of distributed generation including intermittent renewable energy sources introduces several challenges to power systems operation and planning. Although power systems often evolve in a fairly incremental way to meet these challenges, the ambitious objectives for RES development in the next decades (2030-2050), together with the deployment of storage options and active demand, indicate that a more essential paradigm change shift may be required. This paper presents the future challenges and the state of the art of research works that study new concepts for the power systems of the future, with a particular focus on the Web-of-Cells concept, multi-microgrids, the fractal grid approach and autonomic power systems.

Autonomic Performance and Power Control for Co-Located Web Applications in Virtualized Datacenters

In a datacenter, complex and time-varying interactions between various tiers and services of web applications, and the contention of shared resources among co-located virtual machines have significant impact on the user perceived performance and power consumption of the underlying system. We propose and develop APPLEware, an autonomic middleware for joint performance and power control of co-located web applications in virtualized datacenters. It features a distributed control structure that provides predictable performance and energy efficiency for large complex systems. It applies machine learning based self-adaptive modeling to capture the complex and time-varying relationship between the application performance and allocation of resources to various application components, in the face of highly dynamic and bursty workloads. The distributed controllers coordinate with each other and allocate resources to meet the service level agreements of applications in an agile and energy-efficient manner. Experimental results based on a testbed implementation with benchmark applications and large scale simulations demonstrate APPLEware's effectiveness, energy efficiency and scalability.

A New Smart Grid Control and Operation Concept - Autonomic Power System

As the distributed energy resource (DER) penetrance increasing, future power system will be more large-scale with much complexity and uncertainty. Taking an active approach, active distribution network (ADN) can deal with future complex and uncertain challenges to some extent. However, too much re-lying on information exchange of each layer, ADN will lack global adaptability and stability. To make up for the deficiency, this paper proposes a new smart grid control and operation concept, namely autonomic power system (APS). Based on goal-directed mechanism, APS obtains global self-adaptive management. Meanwhile, under the concept of distributed coordination and autonomic control, autonomic units (AUs) in APS coordinate each other and make their own autonomic operation. APS takes not only an optimally and co-ordinately active control of power system, but also brings more intelligence with characteristics of self-configuration, self-optimization, self-protection and self-healing, i.e. self-management and overall self-adaption. Thus, APS completes real-time dynamic goals and makes the operation of future power system more intelligent, effective, safe and reliable.

Autonomic power management with self-healing in server clusters under QoS constraints

The increasing use of server clusters has made their energy consumption an important issue. To address it, several power management techniques are being developed. In order to be useful, these techniques must address the performance and availability implications of reducing energy consumption. This paper presents a power management technique that maintains the quality of service (QoS) levels specified with service level agreements expressed as a threshold for a percentile of the response time. In addition, it provides self-healing by identifying when servers fail and automatically provisioning new servers. The technique is based on balancing the load so that it is concentrated in a small number of servers. For this, it only requires two utilization thresholds and models of performance and power consumption for the application executed in the server. It works in heterogeneous servers and provides overload protection. Several experiments carried out on a prototype show that the technique reduces energy consumption (up to 57.59 % compared to an always-on policy) while providing self-healing and maintaining the QoS.

OPTIMIZING PEAK-HOLDING CONTROLLER SOLAR BATTERY AUTONOMOUS ENERGY INSTALLATION

There is research autonomic power plant with extreme regulation of power solar panels. It is shown that the extreme jog lever, which is part of the controller battery charge, allows the selection of solar battery power more than 98% of the maximum value at step changes in the voltage of the solar battery does not exceed 2 V. The system of the automatic solar tracking the sun uses less than 1% of the daily value of energy produced.

Autonomic dysfunction independently predicts poor cardiovascular outcomes in asymptomatic individuals with type 2 diabetes in the DIAD study.

Objective:The primary aim of this secondary analysis was to determine whether cardiac autonomic neuropathy independently predicted adverse cardiac outcomes in asymptomatic individuals with type 2 diabetes. Additional aims include the determination of the correlation of standard autonomic testing measures and power spectral analysis of heart rate variability, and the association of diabetes-related and cardiac risk factors with cardiac autonomic neuropathy measures.Methods:Cardiac autonomic neuropathy was assessed at the study entry into the Detection of Ischemia in Asymptomatic Diabetics study, using autonomic heart rate and blood pressure testing, and power spectral analysis of heart rate variability. All participants were prospectively followed for the composite clinical outcome of cardiac death, acute coronary syndromes, heart failure, or coronary revascularization.Results:Over 5 years of follow-up, 94 of 1119 (8.4%) subjects developed symptomatic cardiac disease. In unadjusted bivariate analyses, abnormalities in several cardiac autonomic neuropathy tests, including lower Valsalva and Standing Heart Rate Ratios, higher resting Heart Rate, greater systolic blood pressure decrease on standing, and lower low-frequency power, were predictive of symptomatic disease. Independent predictors of poor cardiac outcome were a lower Valsalva Heart Rate Ratio, non-Black ethnicity, longer diabetes duration, higher glycated hemoglobin (HbA1c), insulin use, reported numbness in the extremities, higher pulse pressure, family history of coronary artery disease, and higher waist-to-hip ratio. Clinical factors independently associated with a lower Valsalva Heart Rate Ratio were insulin use, clinical proteinuria, higher pulse pressure, use of angiotensin-converting enzyme inhibitor and non-Black ethnicity.Conclusion:Cardiac autonomic neuropathy predicted adverse cardiac outcomes in asymptomatic type 2 diabetes without known cardiac disease. Clinical variables may help to identify patients who might have cardiac autonomic neuropathy and warrant consideration for autonomic testing.

Portable device for the detection of nitro-explosives based on optical properties of sensor's material

The aim of this study was to design a device for explosives detection. The study design is based on excited steady-state luminescence quenching registration. Sensor's material luminescence intensity reduction occurs due to an interaction of explosives vapours contained in the air. The decrease rate of the luminescence intensity indicates the concentration of vapours. To study the luminescent properties of the sensor element, its luminescence spectra excited by photons with energies in the range 280 - 425 nm were measured. The excitation photoluminescence spectra for luminescence bands of the sensor element were also measured. Excitation source was light emitting diode (375 nm) and luminescent signal receiver was a photodiode (430 - 650 nm) in device designed. The device is operated under control of a program. The algorithm provides multiple operating modes (configuration, calibration, measurement etc.). Thus this device is referred to the class of devices with increased sensitivity to the explosives vapors. The advantages of device are autonomic power, small weight and sizes, simplicity of device operation for measurements.

An integrated lookahead control-based adaptive supervisory framework for autonomic power system applications

Management of the power system infrastructure is a challenge due to its complex dynamics, size, deregulated operation, quality of service demands, and stability concerns. Autonomic computing has recently gained interest on power systems arena for self-healing, self-configuration, self-optimization, and self-protection schemes. Robustness and reliability of the power system can be enhanced with appropriate autonomic control action following the disturbances. Predictive optimal tuning of real time control parameters from the finite set of control actions is considered in this paper to prevent from impending system deterioration. We present the formulation of a generic, higher layer model-based Limited Lookahead Control (LLC) approach that can be applied to a variety of power system applications. The system model, including the lower level controller, load dynamics, and a network assists the controller action. Discrete time control decisions are made based on the optimization of the predicted response to a limited horizon from the developed model. Heuristics based A* algorithm is integrated into the framework to reduce the control overhead for real-time operation. Finally, we present a case studies on Matlab, and RTDS® to demonstrate the applicability of the proposed framework. A nine bus multi-machine power system benchmark is considered for voltage control application with the finite set of capacitor tuning.

Autonomic Performance and Power Control on Virtualized Servers: Survey, Practices, and Trends

Modern datacenter servers hosting popular Internet services face significant and multi-facet challenges in performance and power control. The user-perceived performance is the result of a complex interaction of complex workloads in a very complex underlying system. Highly dynamic and bursty workloads of Internet services fluctuate over multiple time scales, which has a significant impact on processing and power demands of datacenter servers. High-density servers apply virtualization technology for capacity planning and system manageability. Such virtualized computer systems are increasingly large and complex. This paper surveys representative approaches to autonomic performance and power control on virtualized servers, which control the quality of service provided by virtualized resources, improve the energy efficiency of the underlying system, and reduce the burden of complex system management from human operators. It then presents three designed self-adaptive resource management techniques based on machine learning and control for percentile-based response time assurance, non-intrusive energy-efficient performance isolation, and joint performance and power guarantee on virtualized servers. The techniques were implemented and evaluated in a testbed of virtualized servers hosting benchmark applications. Finally, two research trends are identified and discussed for sustainable cloud computing in green datacenters.

Self-organized algorithm in LTE networks: A utility function based optimal power control scheme

In this paper, transmission power control problem for uplink LTE network is investigated and a new autonomic uplink power control scheme was proposed based on utility function, which is a self-organized algorithm. The whole approach is based on the economic concept named utility function. Then a self-organized algorithm is distributed in each mobile users to control the transmission power and to maximize the transmission utility. The proposed scheme is solved through the Lagrange multiplier technique. It is proved that the utility function based algorithm is applicable and the optimal power level can be achieved based on our model.

Autonomic Power Aware Cloud Resources Orchestration Architecture for Web Applications

Endless resources provisioning illusion is the mainstay for cloud computing paradigm. However, the unpredictable volatility nature involving web applications workload demand would highly hinder cloud computing platforms performance, furthermore, expose cloud resources for possible devastation. Accordingly, this work proposes autonomic power aware SLA-oriented cloud resources orchestration two-tier architecture. Despite complexity and uncertainties of the workload fluctuations, the proposed architecture geared for leveraging cloud system resources utilization, ensuring explicit guarantees on web applications’ responsiveness obligations, meanwhile achieving power consumption minimization objectives. The proposed architecture consolidates heuristic methodologies along with control theory approaches in a resource orchestration hierarchical structure. Firstly, an autonomic global controller is presented. The proposed global controller exploits heuristic methodology for mapping virtual machines (VMs) to the appreciate cloud resources in accordance to heuristic multidimensional objectives based placement strategy. Secondly, a proactive fuzzy-logic based local controller is proposed. The proposed local controller aimed at in confronting workloads' sustainable fluctuations via proactive amendment for the placement and provisioning schedules. Furthermore, the proposed local controller oriented towards maintaining active power management policy especially during transient peak of usage, thereby mitigating overall costs, and extending resources capacity and performance capabilities. Simulation results and comparisons demonstrate that the proposed architecture significantly surpasses previous approaches in terms of total energy consumption, furthermore maintaining web applications SLAs objectives despite dynamic workload scenarios.

Autonomic dysfunction in different subtypes of post-acute ischemic stroke

ObjectivesCentral autonomic impairment is frequent in ischemic stroke at acute or chronic stages. The mechanism by which these symptoms occur in patients with ischemic stroke has not been elucidated. This study sought to investigate cardiovascular autonomic function in patients with different subtypes of post-acute ischemic stroke. Methods77 ischemic stroke patients [50 patients with large-artery atherosclerosis (LAA) and 27 patients with small-vessel occlusion (SVO), average 6months after stroke onset] and 37 elderly controls were recruited. All performed Ewing's battery autonomic function tests and power spectral analysis of heart rate variability (HRV). ResultsStroke patients with both LAA and SVO had significantly lower low frequency power spectral density than controls. The prevalence of autonomic dysfunction in both groups (82.0% patients with LAA and 63.0% with SVO) was higher than that in controls (21.6%). Patients with LAA showed impairment of all parasympathetic tests (all P<0.05) and one of the sympathetic tests (mean fall in systolic blood pressure on standing: P=0.058) and those with SVO only showed impairment in two parasympathetic tests (heart rate response to deep breathing: P=0.010; heart rate response to standing: P=0.004) in comparison with controls. Patients with LAA had significantly more impairment than those with SVO in some autonomic parameters (Valsalva ratio: P=0.039; mean fall in systolic blood pressure on standing: P=0.015). ConclusionsIrrespective of the subtype of the ischemia, post-acute stroke patients showed a parasympathetic cardiac deficit. Additionally, parasympathetic and sympathetic cardiovascular modulations were more severely impaired in patients with LAA.