SciCombinator

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Concept: Controllers

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Power and performance management problem in large scale computing systems like data centers has attracted a lot of interests from both enterprises and academic researchers as power saving has become more and more important in many fields. Because of the multiple objectives, multiple influential factors and hierarchical structure in the system, the problem is indeed complex and hard. In this paper, the problem will be investigated in a virtualized computing system. Specifically, it is formulated as a power optimization problem with some constraints on performance. Then, the adaptive controller based on least-square self-tuning regulator(LS-STR) is designed to track performance in the first step; and the resource solved by the controller is allocated in order to minimize the power consumption as the second step. Some simulations are designed to test the effectiveness of this method and to compare it with some other controllers. The simulation results show that the adaptive controller is generally effective: it is applicable for different performance metrics, for different workloads, and for single and multiple workloads; it can track the performance requirement effectively and save the power consumption significantly.

Concepts: Structure, Effectiveness, Hierarchy, Simulation, Operations research, Optimization, Controllers, Power

29

Motor-training software on tablets or smartphones (Apps) offer a low-cost, widely-available solution to supplement arm physiotherapy after stroke. We assessed the proportions of hemiplegic stroke patients who, with their plegic hand, could meaningfully engage with mobile-gaming devices using a range of standard control-methods, as well as by using a novel wireless grip-controller, adapted for neurodisability. We screened all newly-diagnosed hemiplegic stroke patients presenting to a stroke centre over 6 months. Subjects were compared on their ability to control a tablet or smartphone cursor using: finger-swipe, tap, joystick, screen-tilt, and an adapted handgrip. Cursor control was graded as: no movement (0); less than full-range movement (1); full-range movement (2); directed movement (3). In total, we screened 345 patients, of which 87 satisfied recruitment criteria and completed testing. The commonest reason for exclusion was cognitive impairment. Using conventional controls, the proportion of patients able to direct cursor movement was 38-48%; and to move it full-range was 55-67% (controller comparison: p>0.1). By comparison, handgrip enabled directed control in 75%, and full-range movement in 93% (controller comparison: p<0.001). This difference between controllers was most apparent amongst severely-disabled subjects, with 0% achieving directed or full-range control with conventional controls, compared to 58% and 83% achieving these two levels of movement, respectively, with handgrip. In conclusion, hand, or arm, training Apps played on conventional mobile devices are likely to be accessible only to mildly-disabled stroke patients. Technological adaptations such as grip-control can enable more severely affected subjects to engage with self-training software.

Concepts: Stroke, Disability, Smartphone, Controllers, Adaptation, Tablet, Graphical user interface, Windows Mobile

8

Draft regulatory guidance suggests that if the processing of a child’s personal data begins with the consent of a parent, then there is a need to find and defend an enduring consent through the child’s growing capacity and on to their maturity. We consider the implications for health research of the UK Information Commissioner’s Office’s (ICO) suggestion that the relevant test for maturity is the Gillick test, originally developed in the context of medical treatment. Noting the significance of the welfare principle to this test, we examine the implications for the responsibilities of a parent to act as proxy for their child. We argue, contrary to draft ICO guidance, that a data controller might legitimately continue to rely upon parental consent as a legal basis for processing after a child is old enough to provide her own consent. Nevertheless, we conclude that data controllers should develop strategies to seek fresh consent from children as soon as practicable after the data controller has reason to believe they are mature enough to consent independently. Techniques for effective communication, recommended to address challenges associated with Big Data analytics, might have a role here in addressing the dynamic relationship between data subject and processing. Ultimately, we suggest that fair and lawful processing of a child’s data will be dependent upon data controllers taking seriously the truism that consent is ongoing, rather than a one-time event: the core associated responsibility is to continue to communicate with a data subject regarding the processing of personal data.

Concepts: Psychology, Parent, Data analysis, Law, Suggestion, Controllers, Responsibility, Data Protection Act 1998

1

Many studies have aimed to identify the controllers of sweating using ventilated capsules with intradermal microdialysis. It is unclear, however, if the surface area covered by the capsule influences the observed response as a result of differences in the number of sweat glands affected by the infused pharmacological agent relative to the total glands captured by the capsule. We evaluated the area of skin perfused with agents delivered via microdialysis. Thereafter, we developed a specialized sweat capsule (1.1 cm(2)) and compared the sweating response with a classic capsule (2.8 cm(2)). InProtocol 1(n = 6), methacholine was delivered to forearm skin in a dose-dependent manner (1-2000 mmol L(-1)). The area of activated sweat glands was assessed via the modified iodine-paper technique. InProtocol 2(n = 6), the area of inhibited sweat glands induced by ouabain and atropine was assessed during moderate-intensity cycling. Marked variability in the affected skin area was observed (0.9 ± 0.4 to 5.2 ± 1.1 cm(2)). InProtocol 3(n = 6), we compared the attenuation in local sweat rate (LSR) induced by atropine between the new and classic capsule during moderate-intensity cycling. Atropine attenuated sweating as assessed using the new (control: 0.87 ± 0.23 mg min(-1) cm(-2)vs. atropine: 0.54 ± 0.22 mg min(-1) cm(-2);P < 0.01) and classic (control: 0.85 ± 0.33 mg min(-1) cm(-2)vs. atropine: 0.60 ± 0.26 mg min(-1) cm(-2);P = 0.05) capsule designs. Importantly, responses did not differ between capsule designs (P = 0.23). These findings provide critical information regarding the skin surface area perfused by microdialysis and suggest that use of a larger capsule does not alter the mechanistic insight into the sweating response gained when using microdialysis.

Concepts: Skin, Area, Perspiration, Controllers, Exocrine system

1

Emissions from 377 gas actuated (pneumatic) controllers were measured at natural gas production sites and a small number of oil production sites, throughout the United States. A small subset of the devices (19%), with whole gas emission rates in excess of 6 standard cubic feet per hour (scf/h), accounted for 95% of emissions. More than half of the controllers recorded emissions of 0.001 scf/h or less during 15 min of measurement. Pneumatic controllers in level control applications on separators and in compressor applications had higher emission rates than controllers in other types of applications. Regional differences in emissions were observed, with the lowest emissions measured in the Rocky Mountains and the highest emissions in the Gulf Coast. Average methane emissions per controller reported in this work are 17% higher than the average emissions per controller in the 2012 EPA greenhouse gas national emission inventory (2012 GHG NEI, released in 2014); the average of 2.7 controllers per well observed in this work is higher than the 1.0 controllers per well reported in the 2012 GHG NEI.

Concepts: Carbon dioxide, United States, Petroleum, Gulf War, Natural gas, Methane, Controllers, Greenhouse gas

0

Autonomous Underwater Vehicles (AUV) are proving to be a promising platform design for multidisciplinary autonomous operability with a wide range of applications in marine ecology and geoscience. Here, two novel contributions towards increasing the autonomous navigation capability of a new AUV prototype (the Guanay II) as a mix between a propelled vehicle and a glider are presented. Firstly, a vectorial propulsion system has been designed to provide full vehicle maneuverability in both horizontal and vertical planes. Furthermore, two controllers have been designed, based on fuzzy controls, to provide the vehicle with autonomous navigation capabilities. Due to the decoupled system propriety, the controllers in the horizontal plane have been designed separately from the vertical plane. This class of non-linear controllers has been used to interpret linguistic laws into different zones of functionality. This method provided good performance, used as interpolation between different rules or linear controls. Both improvements have been validated through simulations and field tests, displaying good performance results. Finally, the conclusion of this work is that the Guanay II AUV has a solid controller to perform autonomous navigation and carry out vertical immersions.

Concepts: Autonomous robot, Controllers, Horizontal plane, Geodesy, Vertical direction, Aircraft, Vertical plane

0

This paper investigates the tracking control problem of chained-form nonholonomic multiagent systems (MASs). In contrast to the existing works in which some algorithms have been designed for ideal conditions, the destructive factors including external disturbances and input delay are considered in the dynamics of the agents in this work. Two distributed controllers are proposed such that the states of the controlled agents can track the states of the target in the presence of external disturbances and input delay. For this purpose, a distributed controller is firstly suggested based on a switching method to solve the tracking control problem for nonholonomic MASs with external disturbances. Then, the proposed control law is extended based on a state predictor for the tracking control of agents in the presence of input delay. The stability analysis of the two distributed controllers is also provided. Simulation results show the promising performance of the proposed algorithms.

Concepts: U.S. state, Control theory, Cybernetics, The Target, Control, Tracking, Controllers, Multi-agent system

0

In this paper, a practical tuning technique is presented to obtain all stabilizing fractional order PIλ-PDμ controller parameters ensuring stability for processes with time delay using the stability boundary locus and the weighted geometrical center (WGC) methods. The method is based on obtaining of stability regions plotted by using the stability boundary locus in the (kd,kf)-plane and (kp,ki)-plane, and then computing the weighted geometrical centers of these regions. After obtaining PDμ controller parameters using the WGC method from the stability region, desired PIλ controller parameters are computed by the same procedure. This paper provides a simple and efficient tuning method to obtain stabilizing parameters of PIλ-PDμ controller for time delay systems. The important advantages of the method are both calculating of controller parameters without using any complex solution methods and ensuring the stability of closed loop system. Illustrative examples are given to demonstrate the benefits and the simplicity of the proposed method.

Concepts: Mathematics, C, Controllers, Region

0

The production of complex biomolecules by genetically engineered organisms is one of the most promising applications of metabolic engineering and synthetic biology. To obtain processes with high productivity, it is therefore crucial to design and implement efficient dynamic in-vivo regulation strategies. We consider here the microbial biofuel production model of Dunlop et al. (2010) for which we demonstrate that an antithetic dynamic integral control strategy can achieve robust perfect adaptation for the intracellular biofuel concentration in presence of poorly known network parameters and implementation errors in certain rate parameters of the controller. We also show that the maximum equilibrium extracellular biofuel productivity is fully defined by some of the network parameters and, in this respect, it can only be achieved when all the corresponding parameters are perfectly known. Since this optimum is a network property, it cannot be improved by the use of any controller that measures the intracellular biofuel concentration and acts on the production of pump proteins. Additional intrinsic fundamental properties for the process are also unveiled, the most important ones being the existence of a conservation relation between the productivity and the toxicity, a low sensitivity of the optimal productivity with respect to a poor implementation of the set-point for the intracellular biofuel, and a strong intrinsic robustness property of the optimal productivity with respect to poorly known parameters. Taken together, these results demonstrate that a high and robust equilibrium rate of production for the extracellular biofuel can be achieved when the parameters of the model are poorly known and those of the controllers are poorly implemented. Finally, several advantages of the proposed dynamic strategy over a static one are also emphasized.

Concepts: Molecular biology, Metabolism, Enzyme, Organism, Biochemistry, Control theory, Implementation, Controllers

0

Various physiological controllers for left ventricular assist devices (LVADs) have been developed to prevent flow conditions that may lead to left ventricular (LV) suction and overload. In the current study, we selected and implemented six of the most promising physiological controllers presented in literature. We tuned the controllers for the same objectives by using the loop-shaping method from control theory. The in vitro experiments were derived from literature and included different preload, afterload, and contractility variations. All experiments were repeated with an increased or decreased contractility from the baseline pathological circulation and with simulated sensor drift. The controller performances were compared with an LVAD operated at constant speed (CS) and a physiological circulation. During preload variations, all controllers resulted in a pump flow change that resembled the cardiac output response of the physiological circulation. For afterload variations, the response varied among the controllers, whereas some of them presented a high sensitivity to contractility or sensor drift, leading to LV suction and overload. In such cases, the need for recalibration of the controllers or the sensor is indicated. Preload-based physiological controllers showed their clinical significance by outperforming the CS operation and promise many benefits for the LVAD therapy. However, their clinical implementation in the near future for long-term use is highly dependent on the sensor technology and its reliability.

Concepts: Blood, Cardiology, Heart, In vitro, Control theory, Pump, Ventricular assist device, Controllers