Centrifugal compressor controller for minimizing power consumption while avoiding surge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haley, P.F.; Junk, B.S.; Renaud, M.A.

1987-08-18

For use with a variable capacity centrifugal compressor driven by an electric motor, a controller is described for adjusting the capacity of the compressor to satisfy a demand, minimize electric power consumption and avoid a surge condition. The controller consists of: a. means for sensing an operating parameter that is indicative of the capacity of the compressor; b. means for setting a selected setpoint that represents a desired value of the operating parameter; c. surge sensing means for detecting an impending surge by sensing fluctuation in the electric current supplied to the compressor motor, wherein an impending surge is detectedmore » whenever fluctuations in excess of a predetermined amplitude occur in excess of a predetermined frequency; and d. control means, responsive to the operating parameter sensing means, the setpoint setting means, and the surge sensing means, for controlling the compressor, such that its capacity is minimally above a level that would cause a surge condition yet is sufficient to maintain the operating parameter at the setpoint.« less

A Dynamic Neural Network Approach to CBM

DTIC Science & Technology

2011-03-15

high efficiency water cooled heat exchanger positioned on the side of the engine. The air temperature was controlled at the desired set-point by...regulating the inlet water flow in the heat exchanger. The temperature of the cooling water was not regulated. The typical set-point for the air charge...temperature was 127 degF, as used in other durability tests carried out in these facilities. Because the heat exchanger controller was optimized for

California DREAMing: The design of residential demand responsive technology with people in mind

NASA Astrophysics Data System (ADS)

Peffer, Therese Evelyn

Electrical utilities worldwide are exploring "demand response" programs to reduce electricity consumption during peak periods. Californian electrical utilities would like to pass the higher cost of peak demand to customers to offset costs, increase reliability, and reduce peak consumption. Variable pricing strategies require technology to communicate a dynamic price to customers and respond to that price. However, evidence from thermostat and energy display studies as well as research regarding energy-saving behaviors suggests that devices cannot effect residential demand response without the sanction and participation of people. This study developed several technologies to promote or enable residential demand response. First, along with a team of students and professors, I designed and tested the Demand Response Electrical Appliance Manager (DREAM). This wireless network of sensors, actuators, and controller with a user interface provides information to intelligently control a residential heating and cooling system and to inform people of their energy usage. We tested the system with computer simulation and in the laboratory and field. Secondly, as part of my contribution to the team, I evaluated machine-learning to predict a person's seasonal temperature preferences by analyzing existing data from office workers. The third part of the research involved developing an algorithm that generated temperature setpoints based on outdoor temperature. My study compared the simulated energy use using these setpoints to that using the setpoints of a programmable thermostat. Finally, I developed and tested a user interface for a thermostat and in-home energy display. This research tested the effects of both energy versus price information and the context of sponsorship on the behavior of subjects. I also surveyed subjects on the usefulness of various displays. The wireless network succeeded in providing detailed data to enable an intelligent controller and provide feedback to the users. The learning algorithm showed mixed results. The adaptive temperature setpoints saved energy in both annual and summertime simulations. The context in which I introduced the DREAM interface affected behavior, but the type of information displayed did not. The subjects responded that appliance-level feedback and tools that provided choices would be useful in a dynamic tariff environment.

Review of Findings for Human Performance Contribution to Risk in Operating Events

DTIC Science & Technology

2002-03-01

and loss of DC power. Key to this event was failure to control setpoints on safety-related equipment and failure to maintain the load tap changer...34 Therefore, "to optimize task execution at the job site, it is important to align organizational processes and values." Effective team skills are an...reactor was blocked and the water level rapidly dropped to the automatic low-level scram setpoint . Human Performance Issues Control rods were fully

Neural network-based nonlinear model predictive control vs. linear quadratic gaussian control

USGS Publications Warehouse

Cho, C.; Vance, R.; Mardi, N.; Qian, Z.; Prisbrey, K.

1997-01-01

One problem with the application of neural networks to the multivariable control of mineral and extractive processes is determining whether and how to use them. The objective of this investigation was to compare neural network control to more conventional strategies and to determine if there are any advantages in using neural network control in terms of set-point tracking, rise time, settling time, disturbance rejection and other criteria. The procedure involved developing neural network controllers using both historical plant data and simulation models. Various control patterns were tried, including both inverse and direct neural network plant models. These were compared to state space controllers that are, by nature, linear. For grinding and leaching circuits, a nonlinear neural network-based model predictive control strategy was superior to a state space-based linear quadratic gaussian controller. The investigation pointed out the importance of incorporating state space into neural networks by making them recurrent, i.e., feeding certain output state variables into input nodes in the neural network. It was concluded that neural network controllers can have better disturbance rejection, set-point tracking, rise time, settling time and lower set-point overshoot, and it was also concluded that neural network controllers can be more reliable and easy to implement in complex, multivariable plants.

A Time-Domain CMOS Oscillator-Based Thermostat with Digital Set-Point Programming

PubMed Central

Chen, Chun-Chi; Lin, Shih-Hao

2013-01-01

This paper presents a time-domain CMOS oscillator-based thermostat with digital set-point programming [without a digital-to-analog converter (DAC) or external resistor] to achieve on-chip thermal management of modern VLSI systems. A time-domain delay-line-based thermostat with multiplexers (MUXs) was used to substantially reduce the power consumption and chip size, and can benefit from the performance enhancement due to the scaling down of fabrication processes. For further cost reduction and accuracy enhancement, this paper proposes a thermostat using two oscillators that are suitable for time-domain curvature compensation instead of longer linear delay lines. The final time comparison was achieved using a time comparator with a built-in custom hysteresis to generate the corresponding temperature alarm and control. The chip size of the circuit was reduced to 0.12 mm2 in a 0.35-μm TSMC CMOS process. The thermostat operates from 0 to 90 °C, and achieved a fine resolution better than 0.05 °C and an improved inaccuracy of ± 0.6 °C after two-point calibration for eight packaged chips. The power consumption was 30 μW at a sample rate of 10 samples/s. PMID:23385403

Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger

NASA Technical Reports Server (NTRS)

Ungar, Eugene K.; Schunk, Richard G.

2011-01-01

An active thermal control system architecture has been modified to include a regenerative heat exchanger (regenerator) inboard of the radiator. Rather than using a radiator bypass valve a regenerative heat exchanger is placed inboard of the radiators. A regenerator cold side bypass valve is used to set the return temperature. During operation, the regenerator bypass flow is varied, mixing cold radiator return fluid and warm regenerator outlet fluid to maintain the system setpoint. At the lowest heat load for stable operation, the bypass flow is closed off, sending all of the flow through the regenerator. This lowers the radiator inlet temperature well below the system set-point while maintaining full flow through the radiators. By using a regenerator bypass flow control to maintain system setpoint, the required minimum heat load to avoid radiator freezing can be reduced by more than half compared to a radiator bypass system.

The Development of a Control System for a 5 Kilowatt Free Piston Stirling Space Convertor

NASA Technical Reports Server (NTRS)

Kirby, Raymond L.; Vitale, Nicholas

2008-01-01

The new NASA Vision for Exploration, announced by President Bush in January 2004, proposes an ambitious program that plans to return astronauts to the moon by the 2018 time frame. A recent NASA study entitled "Affordable Fission Surface Power Study" recommended a 40 kWe, 900 K, NaK-cooled, Stirling conversion for 2020 launch. Use of two of the nominal 5 kW converters allows the system to be dynamically balanced. A group of four dual-converter combinations that would yield 40 kWe can be tested to validate the viability of Stirling technology for space fission surface power systems. The work described in this paper deals specifically with the control system for the 5 kW convertor described in the preceding paragraph. This control system is responsible for maintaining piston stroke to a setpoint in the presence of various disturbances including electrical load variations. Pulse starting of the FSPE convertor is also an inherent part of such a control system. Finally, the ability to throttle the engine to match the required output power is discussed in terms of setpoint control. Several novel ideas have been incorporated into the piston stroke control strategy that will engender a stable response to disturbances in the presence of midpoint drift while providing useful data regarding the position of both the power piston and displacer.

The Development of a Control System for a 5 Kilowatt Free Piston Stirling Engine Convertor

NASA Technical Reports Server (NTRS)

Kirby, Raymond L.; Vitale, Nick

2008-01-01

The new NASA Vision for Exploration, announced by President Bush in January 2004, proposes an ambitious program that plans to return astronauts to the moon by the 2018 time frame. A recent NASA study entitled "Affordable Fission Surface Power Study" recommended a 40 kWe, 900 K, NaK-cooled, Stirling convertors for 2020 launch. Use of two of the nominal 5 kW convertors allows the system to be dynamically balanced. A group of four dual-convertor combinations that would yield 40 kWe can be tested to validate the viability of Stirling technology for space fission surface power systems. The work described in this paper deals specifically with the control system for the 5 kW convertor described in the preceding paragraph. This control system is responsible for maintaining piston stroke to a setpoint in the presence of various disturbances including electrical load variations. Pulse starting of the Free Piston Stirling Engine (FPSE) convertor is also an inherent part of such a control system. Finally, the ability to throttle the engine to match the required output power is discussed in terms of setpoint control. Several novel ideas have been incorporated into the piston stroke control strategy that will engender a stable response to disturbances in the presence of midpoint drift while providing useful data regarding the position of both the power piston and displacer.

Electrothermal adsorption and desorption of volatile organic compounds on activated carbon fiber cloth.

PubMed

Son, H K; Sivakumar, S; Rood, M J; Kim, B J

2016-01-15

Adsorption is an effective means to selectively remove volatile organic compounds (VOCs) from industrial gas streams and is particularly of use for gas streams that exhibit highly variable daily concentrations of VOCs. Adsorption of such gas streams by activated carbon fiber cloths (ACFCs) and subsequent controlled desorption can provide gas streams of well-defined concentration that can then be more efficiently treated by biofiltration than streams exhibiting large variability in concentration. In this study, we passed VOC-containing gas through an ACFC vessel for adsorption and then desorption in a concentration-controlled manner via electrothermal heating. Set-point concentrations (40-900 ppm(v)) and superficial gas velocity (6.3-9.9 m/s) were controlled by a data acquisition and control system. The results of the average VOC desorption, desorption factor and VOC in-and-out ratio were calculated and compared for various gas set-point concentrations and superficial gas velocities. Our results reveal that desorption is strongly dependent on the set-point concentration and that the VOC desorption rate can be successfully equalized and controlled via an electrothermal adsorption system. Copyright © 2015 Elsevier B.V. All rights reserved.

Control of electrothermal heating during regeneration of activated carbon fiber cloth.

PubMed

Johnsen, David L; Mallouk, Kaitlin E; Rood, Mark J

2011-01-15

Electrothermal swing adsorption (ESA) of organic gases generated by industrial processes can reduce atmospheric emissions and allow for reuse of recovered product. Desorption energy efficiency can be improved through control of adsorbent heating, allowing for cost-effective separation and concentration of these gases for reuse. ESA experiments with an air stream containing 2000 ppm(v) isobutane and activated carbon fiber cloth (ACFC) were performed to evaluate regeneration energy consumption. Control logic based on temperature feedback achieved select temperature and power profiles during regeneration cycles while maintaining the ACFC's mean regeneration temperature (200 °C). Energy requirements for regeneration were independent of differences in temperature/power oscillations (1186-1237 kJ/mol of isobutane). ACFC was also heated to a ramped set-point, and the average absolute error between the actual and set-point temperatures was small (0.73%), demonstrating stable control as set-point temperatures vary, which is necessary for practical applications (e.g., higher temperatures for higher boiling point gases). Additional logic that increased the maximum power application at lower ACFC temperatures resulted in a 36% decrease in energy consumption. Implementing such control logic improves energy efficiency for separating and concentrating organic gases for post-desorption liquefaction of the organic gas for reuse.

Comparative study of a learning fuzzy PID controller and a self-tuning controller.

PubMed

Kazemian, H B

2001-01-01

The self-organising fuzzy controller is an extension of the rule-based fuzzy controller with an additional learning capability. The self-organising fuzzy (SOF) is used as a master controller to readjust conventional PID gains at the actuator level during the system operation, copying the experience of a human operator. The application of the self-organising fuzzy PID (SOF-PID) controller to a 2-link non-linear revolute-joint robot-arm is studied using path tracking trajectories at the setpoint. For the purpose of comparison, the same experiments are repeated by using the self-tuning controller subject to the same data supplied at the setpoint. For the path tracking experiments, the output trajectories of the SOF-PID controller followed the specified path closer and smoother than the self-tuning controller.

Development of an Open Building Automation System Specification Based on ANSI/ASHRAE 135-2004 (BACnet(R) Communications Protocol: A Technical Assessment

DTIC Science & Technology

2007-02-01

on/off control), trending and trend reports, load shedding/load manage- ment, remote setpoint adjustment, initial diagnosis of a service call and...building-specific operational data such as on/off scheduling com- mands, setpoints , and outside air temperature. With help from several other agencies and...interface for monitoring 3. Provide one interface for device/system management/configuration 4. ( Optimally ) provide one interface for device

Development of an Open Building Automation System Specification Based on ANSI/ASHRAE 135-2004 (BACnet(Registered) Communications Protocol): A Technical Assessment

DTIC Science & Technology

2007-02-01

on/off control), trending and trend reports, load shedding/load manage- ment, remote setpoint adjustment, initial diagnosis of a service call and...building-specific operational data such as on/off scheduling com- mands, setpoints , and outside air temperature. With help from several other agencies and...interface for monitoring 3. Provide one interface for device/system management/configuration 4. ( Optimally ) provide one interface for device

Control of gravitropic orientation. I. Non-vertical orientation by primary roots of maize results from decay of competence for orthogravitropic induction

NASA Technical Reports Server (NTRS)

LaMotte, Clifford E.; Pickard, Barbara G.

2004-01-01

Plant organs may respond to gravity by vertical (orthogravitropic), oblique (plagiogravitropic) or horizontal (diagravitropic) growth. Primary roots of maize (Zea mays L.) provide a good system for studying such behaviours because they are reportedly capable of displaying all three responses. In current work using maize seedlings of the Silver Queen cultivar, stabilisation of growth at an oblique orientation was commonplace. Hypothetically, plagiogravitropism may be accomplished either by a process we call graded orthogravitropism or by hunting about a sensed non-vertical setpoint. In graded orthotropism primary bending is unidirectional and depends on facilitative stimuli that determine its extent. The hallmark of the setpoint mechanism is restorative curvature of either sign following a displacement; both diagravitropism and orthogravitropism are based on setpoints. Roots settled in a plagiogravitropic orientation were tested with various illumination and displacement protocols designed to distinguish between these two hypotheses. The tests refuted the setpoint hypothesis and supported that of graded orthotropism. No evidence of diagravitropism could be found, thus, earlier claims were likely based on inadequately controlled observations of graded orthotropism. We propose that orthotropism is graded by the sequential action of dual gravity receptors: induction of a vectorial gravitropic response requires gravitational induction of a separate facilitative response, whose decay in the absence of fresh stimuli can brake gravitropism at plagiotropic angles.

Tuning maps for setpoint changes and load disturbance upsets in a three capacity process under multivariable control

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Smith, Ira C.

1991-01-01

Tuning maps are an aid in the controller tuning process because they provide a convenient way for the plant operator to determine the consequences of adjusting different controller parameters. In this application the maps provide a graphical representation of the effect of varying the gains in the state feedback matrix on startup and load disturbance transients for a three capacity process. Nominally, the three tank system, represented in diagonal form, has a Proportional-Integral control on each loop. Cross coupling is then introduced between the loops by using non-zero off-diagonal proportional parameters. Changes in transient behavior due to setpoint and load changes are examined by varying the gains of the cross coupling terms.

Systems and methods for energy cost optimization in a building system

DOEpatents

Turney, Robert D.; Wenzel, Michael J.

2016-09-06

Methods and systems to minimize energy cost in response to time-varying energy prices are presented for a variety of different pricing scenarios. A cascaded model predictive control system is disclosed comprising an inner controller and an outer controller. The inner controller controls power use using a derivative of a temperature setpoint and the outer controller controls temperature via a power setpoint or power deferral. An optimization procedure is used to minimize a cost function within a time horizon subject to temperature constraints, equality constraints, and demand charge constraints. Equality constraints are formulated using system model information and system state information whereas demand charge constraints are formulated using system state information and pricing information. A masking procedure is used to invalidate demand charge constraints for inactive pricing periods including peak, partial-peak, off-peak, critical-peak, and real-time.

Design Guidance for Command, Control, Communications, and Intelligence (C3I) Facility Cooling Systems

DTIC Science & Technology

1989-05-01

Typical ranges are from 50 to 70 OF. If a chiller is dedicated to serving water-cooled electronic equipment, the chilled water temperature setpoint can...can be satisfied with 50 OF chilled water. The COP of the dedicated chiller is improved by raising the chilled water setpoint , and the total life-cycle...USACERL TECHNICAL REPORT E-89/10 May 1989 Studies in Optimizing HVAC Hardware for C31 Facilities US Army Corps of Engineers Construction Engineering

Parametric Analysis of Energy Consumption in Army Buildings by the Building Loads Analysis and System Thermodynamics (BLAST) Computer Program.

DTIC Science & Technology

1980-08-01

orientation, and HVAC systems have on three Army buildings in five different climatic regions. f Optimization of EnerV Usage in Military Facilities...The clinic’s environment is maintained by a multizone air-handling unit served by its own boiler and chiller . The building was modeled with 30... setpoints for the space temperature. This type of throttling range allows the heating system to control around a throttling range of 67 to 69oF (19 to 200

Robust guaranteed cost tracking control of quadrotor UAV with uncertainties.

PubMed

Xu, Zhiwei; Nian, Xiaohong; Wang, Haibo; Chen, Yinsheng

2017-07-01

In this paper, a robust guaranteed cost controller (RGCC) is proposed for quadrotor UAV system with uncertainties to address set-point tracking problem. A sufficient condition of the existence for RGCC is derived by Lyapunov stability theorem. The designed RGCC not only guarantees the whole closed-loop system asymptotically stable but also makes the quadratic performance level built for the closed-loop system have an upper bound irrespective to all admissible parameter uncertainties. Then, an optimal robust guaranteed cost controller is developed to minimize the upper bound of performance level. Simulation results verify the presented control algorithms possess small overshoot and short setting time, with which the quadrotor has ability to perform set-point tracking task well. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Control methods and systems for indirect evaporative coolers

DOEpatents

Woods, Jason; Kozubal, Erik

2015-09-22

A control method for operating an indirect evaporative cooler to control temperature and humidity. The method includes operating an airflow control device to provide supply air at a flow rate to a liquid desiccant dehumidifier. The supply air flows through the dehumidifier and an indirect evaporative cooler prior to exiting an outlet into a space. The method includes operating a pump to provide liquid desiccant to the liquid desiccant dehumidifier and sensing a temperature of an airstream at the outlet of the indirect evaporative cooler. The method includes comparing the temperature of the airstream at the outlet to a setpoint temperature at the outlet and controlling the pump to set the flow rate of the liquid desiccant. The method includes sensing space temperature, comparing the space temperature with a setpoint temperature, and controlling the airflow control device to set the flow rate of the supply air based on the comparison.

Tool for the Integrated Dynamic Numerical Propulsion System Simulation (NPSS)/Turbine Engine Closed-Loop Transient Analysis (TTECTrA) User's Guide

NASA Technical Reports Server (NTRS)

Chin, Jeffrey C.; Csank, Jeffrey T.

2016-01-01

The Tool for Turbine Engine Closed-Loop Transient Analysis (TTECTrA ver2) is a control design tool thatenables preliminary estimation of transient performance for models without requiring a full nonlinear controller to bedesigned. The program is compatible with subsonic engine models implemented in the MATLAB/Simulink (TheMathworks, Inc.) environment and Numerical Propulsion System Simulation (NPSS) framework. At a specified flightcondition, TTECTrA will design a closed-loop controller meeting user-defined requirements in a semi or fully automatedfashion. Multiple specifications may be provided, in which case TTECTrA will design one controller for each, producing acollection of controllers in a single run. Each resulting controller contains a setpoint map, a schedule of setpointcontroller gains, and limiters; all contributing to transient characteristics. The goal of the program is to providesteady-state engine designers with more immediate feedback on the transient engine performance earlier in the design cycle.

Variable current speed controller for eddy current motors

DOEpatents

Gerth, H.L.; Bailey, J.M.; Casstevens, J.M.; Dixon, J.H.; Griffith, B.O.; Igou, R.E.

1982-03-12

A speed control system for eddy current motors is provided in which the current to the motor from a constant frequency power source is varied by comparing the actual motor speed signal with a setpoint speed signal to control the motor speed according to the selected setpoint speed. A three-phase variable voltage autotransformer is provided for controlling the voltage from a three-phase power supply. A corresponding plurality of current control resistors is provided in series with each phase of the autotransformer output connected to inputs of a three-phase motor. Each resistor is connected in parallel with a set of normally closed contacts of plurality of relays which are operated by control logic. A logic circuit compares the selected speed with the actual motor speed obtained from a digital tachometer monitoring the motor spindle speed and operated the relays to add or substract resistance equally in each phase of the motor input to vary the motor current to control the motor at the selected speed.

Photovoltaic Inverter Controllers Seeking AC Optimal Power Flow Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Dhople, Sairaj V.; Giannakis, Georgios B.

This paper considers future distribution networks featuring inverter-interfaced photovoltaic (PV) systems, and addresses the synthesis of feedback controllers that seek real- and reactive-power inverter setpoints corresponding to AC optimal power flow (OPF) solutions. The objective is to bridge the temporal gap between long-term system optimization and real-time inverter control, and enable seamless PV-owner participation without compromising system efficiency and stability. The design of the controllers is grounded on a dual ..epsilon..-subgradient method, while semidefinite programming relaxations are advocated to bypass the non-convexity of AC OPF formulations. Global convergence of inverter output powers is analytically established for diminishing stepsize rules formore » cases where: i) computational limits dictate asynchronous updates of the controller signals, and ii) inverter reference inputs may be updated at a faster rate than the power-output settling time.« less

Center for the Built Environment: Setpoint Energy Savings Calculator

Science.gov Websites

. Arens, and H. Zhang, 2014. Extending air temperature setpoints: Simulated energy savings and design Near-ZNE Buildings Setpoint Energy Savings Calculator UFAD Case Studies UFAD Cooling Design Tool UFAD Cost Analysis UFAD Design Guide UFAD East End UFAD Energy Modeling UFAD Plenum Performance UFAD

Definition of a Robust Supervisory Control Scheme for Sodium-Cooled Fast Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponciroli, R.; Passerini, S.; Vilim, R. B.

In this work, an innovative control approach for metal-fueled Sodium-cooled Fast Reactors is proposed. With respect to the classical approach adopted for base-load Nuclear Power Plants, an alternative control strategy for operating the reactor at different power levels by respecting the system physical constraints is presented. In order to achieve a higher operational flexibility along with ensuring that the implemented control loops do not influence the system inherent passive safety features, a dedicated supervisory control scheme for the dynamic definition of the corresponding set-points to be supplied to the PID controllers is designed. In particular, the traditional approach based onmore » the adoption of tabulated lookup tables for the set-point definition is found not to be robust enough when failures of the implemented SISO (Single Input Single Output) actuators occur. Therefore, a feedback algorithm based on the Reference Governor approach, which allows for the optimization of reference signals according to the system operating conditions, is proposed.« less

Teleoperation of steerable flexible needles by combining kinesthetic and vibratory feedback.

PubMed

Pacchierotti, Claudio; Abayazid, Momen; Misra, Sarthak; Prattichizzo, Domenico

2014-01-01

Needle insertion in soft-tissue is a minimally invasive surgical procedure that demands high accuracy. In this respect, robotic systems with autonomous control algorithms have been exploited as the main tool to achieve high accuracy and reliability. However, for reasons of safety and responsibility, autonomous robotic control is often not desirable. Therefore, it is necessary to focus also on techniques enabling clinicians to directly control the motion of the surgical tools. In this work, we address that challenge and present a novel teleoperated robotic system able to steer flexible needles. The proposed system tracks the position of the needle using an ultrasound imaging system and computes needle's ideal position and orientation to reach a given target. The master haptic interface then provides the clinician with mixed kinesthetic-vibratory navigation cues to guide the needle toward the computed ideal position and orientation. Twenty participants carried out an experiment of teleoperated needle insertion into a soft-tissue phantom, considering four different experimental conditions. Participants were provided with either mixed kinesthetic-vibratory feedback or mixed kinesthetic-visual feedback. Moreover, we considered two different ways of computing ideal position and orientation of the needle: with or without set-points. Vibratory feedback was found more effective than visual feedback in conveying navigation cues, with a mean targeting error of 0.72 mm when using set-points, and of 1.10 mm without set-points.

Design of set-point weighting PIλ + Dμ controller for vertical magnetic flux controller in Damavand tokamak.

PubMed

Rasouli, H; Fatehi, A

2014-12-01

In this paper, a simple method is presented for tuning weighted PI(λ) + D(μ) controller parameters based on the pole placement controller of pseudo-second-order fractional systems. One of the advantages of this controller is capability of reducing the disturbance effects and improving response to input, simultaneously. In the following sections, the performance of this controller is evaluated experimentally to control the vertical magnetic flux in Damavand tokamak. For this work, at first a fractional order model is identified using output-error technique in time domain. For various practical experiments, having desired time responses for magnetic flux in Damavand tokamak, is vital. To approach this, at first the desired closed loop reference models are obtained based on generalized characteristic ratio assignment method in fractional order systems. After that, for the identified model, a set-point weighting PI(λ) + D(μ) controller is designed and simulated. Finally, this controller is implemented on digital signal processor control system of the plant to fast/slow control of magnetic flux. The practical results show appropriate performance of this controller.

40 CFR 86.1868-12 - CO2 credits for improving the efficiency of air conditioning systems.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Creditvalue (g/mi) Reduced reheat, with externally-controlled, variable-displacement compressor (e.g. a compressor that controls displacement based on temperature setpoint and/or cooling demand of the air...-controlled, fixed-displacement or pneumatic variable displacement compressor (e.g. a compressor that controls...

Automated force controller for amplitude modulation atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyagi, Atsushi, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr; Scheuring, Simon, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr

Atomic Force Microscopy (AFM) is widely used in physics, chemistry, and biology to analyze the topography of a sample at nanometer resolution. Controlling precisely the force applied by the AFM tip to the sample is a prerequisite for faithful and reproducible imaging. In amplitude modulation (oscillating) mode AFM, the applied force depends on the free and the setpoint amplitudes of the cantilever oscillation. Therefore, for keeping the applied force constant, not only the setpoint amplitude but also the free amplitude must be kept constant. While the AFM user defines the setpoint amplitude, the free amplitude is typically subject to uncontrollablemore » drift, and hence, unfortunately, the real applied force is permanently drifting during an experiment. This is particularly harmful in biological sciences where increased force destroys the soft biological matter. Here, we have developed a strategy and an electronic circuit that analyzes permanently the free amplitude of oscillation and readjusts the excitation to maintain the free amplitude constant. As a consequence, the real applied force is permanently and automatically controlled with picoNewton precision. With this circuit associated to a high-speed AFM, we illustrate the power of the development through imaging over long-duration and at various forces. The development is applicable for all AFMs and will widen the applicability of AFM to a larger range of samples and to a larger range of (non-specialist) users. Furthermore, from controlled force imaging experiments, the interaction strength between biomolecules can be analyzed.« less

Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger with Bypass Setpoint Temperature Control

NASA Technical Reports Server (NTRS)

Ungar, Eugene K.

2008-01-01

Spacecraft radiators are sized for their maximum heat load in their warmest thermal environment, but must operate at reduced heat loads and in colder environments. For systems where the radiator environment can be colder than the working fluid freezing temperature, radiator freezing becomes an issue. Radiator freezing has not been a major issue for the Space Shuttle and the International Space Station (ISS) active thermal control systems (ATCSs) because they operate in environments that are warm relative to the freezing point of their external coolants (Freon-21 and ammonia, respectively). For a vehicle that lands at the Lunar South Pole, the design thermal environment is 215K, but the radiator working fluid must also be kept from freezing during the 0 K sink of transit. A radiator bypass flow control design such as those used on the Space Shuttle and ISS requires more than 30% of the design heat load to avoid radiator freezing during transit - even with a very low freezing point working fluid. By changing the traditional ATCS architecture to include a regenerating heat exchanger inboard of the radiator and by using a regenerator bypass flow control valve to maintain system setpoint, the required minimum heat load can be reduced by more than half. This gives the spacecraft much more flexibility in design and operation. The present work describes the regenerator bypass ATCS setpoint control methodology. It includes analytical results comparing the performance of this system to the traditional radiator bypass system. Finally, a summary of the advantages of the regenerator bypass system are presented.

40 CFR 86.1868-12 - CO2 credits for improving the efficiency of air conditioning systems.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., engine displacement, transmission class and configuration, interior volume, climate control system type... Creditvalue (g/mi) Reduced reheat, with externally-controlled, variable-displacement compressor (e.g. a compressor that controls displacement based on temperature setpoint and/or cooling demand of the air...

The optimal dissolved oxygen profile in a nitrifying activated sludge process - comparisons with ammonium feedback control.

PubMed

Amand, L; Carlsson, B

2013-01-01

Ammonium feedback control is increasingly used to determine the dissolved oxygen (DO) set-point in aerated activated sludge processes for nitrogen removal. This study compares proportional-integral (PI) ammonium feedback control with a DO profile created from a mathematical minimisation of the daily air flow rate. All simulated scenarios are set to reach the same treatment level of ammonium, based on a daily average concentration. The influent includes daily variations only and the model has three aerated zones. Comparisons are made at different plant loads and DO concentrations, and the placement of the ammonium sensor is investigated. The results show that ammonium PI control can achieve the best performance if the DO set-point is limited at a maximum value and with little integral action in the controller. Compared with constant DO control the best-performing ammonium controller can achieve 1-3.5% savings in the air flow rate, while the optimal solution can achieve a 3-7% saving. Energy savings are larger when operating at higher DO concentrations.

Low phosphate alters lateral root setpoint angle and gravitropism.

PubMed

Bai, Hanwen; Murali, Bhavna; Barber, Kevin; Wolverton, Chris

2013-01-01

Lateral roots, responsible for water and nutrient uptake, maintain nonvertical angles throughout development. Soil phosphate is one limiting nutrient for plant growth that is known to induce changes to root system architecture, such as increased lateral root formation. This study seeks to determine whether phosphate concentration affects lateral root orientation in addition to its previously described influences on root architecture. Images of intact Arabidopsis root systems were recorded for 24 h, and lateral root tip angles were measured for wild-type and mutant pgm-1 and pin3-1 roots on a full or low phosphate medium. Setpoint angles of unstimulated root systems were determined, as were gravitropic responses of lateral roots over time. The root system setpoint angles of wild-type and mutant pin3-1 roots showed a shift toward a more vertical orientation on low orthophosphate (Pi) medium. The gravitropic responses of both pgm-1 and pin3-1 roots on low Pi medium was elevated relative to control Pi medium. Mutations in two phosphate transporters with high levels of expression in the root showed a gravitropic response similar to wild-type roots grown on low Pi, supporting a role for Pi status in regulating lateral root gravitropism. Lateral root orientation and gravitropism are affected by Pi status and may provide an important additional parameter for describing root responses to low Pi. The data also support the conclusion that gravitropic setpoint angle reacts to nutrient status and is under dynamic regulation.

Design of set-point weighting PI{sup λ} + D{sup μ} controller for vertical magnetic flux controller in Damavand tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasouli, H.; Fatehi, A.

2014-12-15

In this paper, a simple method is presented for tuning weighted PI{sup λ} + D{sup μ} controller parameters based on the pole placement controller of pseudo-second-order fractional systems. One of the advantages of this controller is capability of reducing the disturbance effects and improving response to input, simultaneously. In the following sections, the performance of this controller is evaluated experimentally to control the vertical magnetic flux in Damavand tokamak. For this work, at first a fractional order model is identified using output-error technique in time domain. For various practical experiments, having desired time responses for magnetic flux in Damavand tokamak,more » is vital. To approach this, at first the desired closed loop reference models are obtained based on generalized characteristic ratio assignment method in fractional order systems. After that, for the identified model, a set-point weighting PI{sup λ} + D{sup μ} controller is designed and simulated. Finally, this controller is implemented on digital signal processor control system of the plant to fast/slow control of magnetic flux. The practical results show appropriate performance of this controller.« less

Advances in thermal control and performance of the MMT M1 mirror

NASA Astrophysics Data System (ADS)

Gibson, J. D.; Williams, G. G.; Callahan, S.; Comisso, B.; Ortiz, R.; Williams, J. T.

2010-07-01

Strategies for thermal control of the 6.5-meter diameter borosilicate honeycomb primary (M1) mirror at the MMT Observatory have included: 1) direct control of ventilation system chiller setpoints by the telescope operator, 2) semiautomated control of chiller setpoints, using a fixed offset from the ambient temperature, and 3) most recently, an automated temperature controller for conditioned air. Details of this automated controller, including the integration of multiple chillers, heat exchangers, and temperature/dew point sensors, are presented here. Constraints and sanity checks for thermal control are also discussed, including: 1) mirror and hardware safety, 2) aluminum coating preservation, and 3) optimization of M1 thermal conditions for science acquisition by minimizing both air-to-glass temperature differences, which cause mirror seeing, and internal glass temperature gradients, which cause wavefront errors. Consideration is given to special operating conditions, such as high dew and frost points. Precise temperature control of conditioned ventilation air as delivered to the M1 mirror cell is also discussed. The performance of the new automated controller is assessed and compared to previous control strategies. Finally, suggestions are made for further refinement of the M1 mirror thermal control system and related algorithms.

Touch and gravitropic set-point angle interact to modulate gravitropic growth in roots

NASA Technical Reports Server (NTRS)

Massa, G. D.; Gilroy, S.

2003-01-01

Plant roots must sense and respond to a variety of environmental stimuli as they grow through the soil. Touch and gravity represent two of the mechanical signals that roots must integrate to elicit the appropriate root growth patterns and root system architecture. Obstacles such as rocks will impede the general downwardly directed gravitropic growth of the root system and so these soil features must be sensed and this information processed for an appropriate alteration in gravitropic growth to allow the root to avoid the obstruction. We show that primary and lateral roots of Arabidopsis do appear to sense and respond to mechanical barriers placed in their path of growth in a qualitatively similar fashion. Both types of roots exhibited a differential growth response upon contacting the obstacle that directed the main axis of elongation parallel to the barrier. This growth habit was maintained until the obstacle was circumvented, at which point normal gravitropic growth was resumed. Thus, the gravitational set-point angle of the primary and lateral roots prior to encountering the barrier were 95 degrees and 136 degrees respectively and after growing off the end of the obstacle identical set-point angles were reinstated. However, whilst tracking across the barrier, quantitative differences in response were observed between these two classes of roots. The root tip of the primary root maintained an angle of 136 degrees to the horizontal as it traversed the barrier whereas the lateral roots adopted an angle of 154 degrees. Thus, this root tip angle appeared dependent on the gravitropic set-point angle of the root type with the difference in tracking angle quantitatively reflecting differences in initial set-point angle. Concave and convex barriers were also used to analyze the response of the root to tracking along a continuously varying surface. The roots maintained the a fairly fixed angle to gravity on the curved surface implying a constant resetting of this tip angle/tracking response as the curve of the surface changed. We propose that the interaction of touch and gravity sensing/response systems combine to strictly control the tropic growth of the root. Such signal integration is likely a critical part of growth control in the stimulus-rich environment of the soil. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Exponentially Stabilizing Robot Control Laws

NASA Technical Reports Server (NTRS)

Wen, John T.; Bayard, David S.

1990-01-01

New class of exponentially stabilizing laws for joint-level control of robotic manipulators introduced. In case of set-point control, approach offers simplicity of proportion/derivative control architecture. In case of tracking control, approach provides several important alternatives to completed-torque method, as far as computational requirements and convergence. New control laws modified in simple fashion to obtain asymptotically stable adaptive control, when robot model and/or payload mass properties unknown.

A simple model-based control for Pichia pastoris allows a more efficient heterologous protein production bioprocess.

PubMed

Cos, Oriol; Ramon, Ramon; Montesinos, José Luis; Valero, Francisco

2006-09-05

A predictive control algorithm coupled with a PI feedback controller has been satisfactorily implemented in the heterologous Rhizopus oryzae lipase production by Pichia pastoris methanol utilization slow (Mut(s)) phenotype. This control algorithm has allowed the study of the effect of methanol concentration, ranging from 0.5 to 1.75 g/L, on heterologous protein production. The maximal lipolytic activity (490 UA/mL), specific yield (11,236 UA/g(biomass)), productivity (4,901 UA/L . h), and specific productivity (112 UA/g(biomass)h were reached for a methanol concentration of 1 g/L. These parameters are almost double than those obtained with a manual control at a similar methanol set-point. The study of the specific growth, consumption, and production rates showed different patterns for these rates depending on the methanol concentration set-point. Results obtained have shown the need of implementing a robust control scheme when reproducible quality and productivity are sought. It has been demonstrated that the model-based control proposed here is a very efficient, robust, and easy-to-implement strategy from an industrial application point of view. (c) 2006 Wiley Periodicals, Inc.

Control strategy optimization of HVAC plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Facci, Andrea Luigi; Zanfardino, Antonella; Martini, Fabrizio

In this paper we present a methodology to optimize the operating conditions of heating, ventilation and air conditioning (HVAC) plants to achieve a higher energy efficiency in use. Semi-empiric numerical models of the plant components are used to predict their performances as a function of their set-point and the environmental and occupied space conditions. The optimization is performed through a graph-based algorithm that finds the set-points of the system components that minimize energy consumption and/or energy costs, while matching the user energy demands. The resulting model can be used with systems of almost any complexity, featuring both HVAC components andmore » energy systems, and is sufficiently fast to make it applicable to real-time setting.« less

Control Strategies for Reducing Heating, Ventilating, and Air Conditioning (HVAC) Energy Consumption in Single Buildings.

DTIC Science & Technology

1983-03-01

economizer and enthalpy cycles, scheduled temperature reset, chiller control and chilled water reset, boiler control and hot water temperature reset...temperature reset, chiller control and chilled water reset, boiler control and hot water temperature reset, and condenser water temperature reset. Recent...day-night setback. Day-night setback is the strategy of reducing the heating space temperature setpoint or raising the cooling space temperature

Control of liquid cooling garments: technical control of body heat storage.

PubMed

Hexamer, M; Werner, J

1996-07-01

This paper describes a concept of how liquid cooling garments (LCG) can be automatically controlled by the objective physiological state. The technically controlled parameter was mean body temperature which was calculated from the measured rectal and mean skin temperature. This was motivated by the fact that mean body temperature is the basis for estimating body heat storage, a commonly used measure of thermal strain. Here the setpoint of mean body temperature was the individual value taken in a preceeding resting period and it was the task of the technical controller to keep the actual value of mean body temperature as close as possible to the setpoint. The most important tuning parameters of the controller were the weighting coefficients for rectal and mean skin temperature in the calculation for mean body temperature. The ratio of these two coefficients determined the degree of compensation for any rectal temperature shift by changing mean skin temperature. Test experiments were carried out (n = 5) in which the controller was able to clamp mean body temperature to the setpoint thereby preventing heat storage. Although exercise rate (75 W) was the same, sweating and warm discomfort occurred in some cases due to the individual rectal temperature rise. Another source of discomfort were delays or paradoxical time courses of rectal temperature at the start or end of exercise which were responsible for a delayed onset of cooling or heating. To avoid these effects, the oxygen consumption signal, which is very fast and directly correlated to the exercise rate, was added to the control loop. Each increase of this parameter above its resting level lowered suit temperature. As heat storage should not be completely rejected by this new signal pathway, the controller for mean body temperature still remained active. The repetition of the experiments showed that the load error in the control loop was smaller and the comfort level in transient phases higher. For a further improvement of this concept it is recommended that the weighting coefficients be tuned to the individual requirements.

Viral genetic variation accounts for a third of variability in HIV-1 set-point viral load in Europe.

PubMed

Blanquart, François; Wymant, Chris; Cornelissen, Marion; Gall, Astrid; Bakker, Margreet; Bezemer, Daniela; Hall, Matthew; Hillebregt, Mariska; Ong, Swee Hoe; Albert, Jan; Bannert, Norbert; Fellay, Jacques; Fransen, Katrien; Gourlay, Annabelle J; Grabowski, M Kate; Gunsenheimer-Bartmeyer, Barbara; Günthard, Huldrych F; Kivelä, Pia; Kouyos, Roger; Laeyendecker, Oliver; Liitsola, Kirsi; Meyer, Laurence; Porter, Kholoud; Ristola, Matti; van Sighem, Ard; Vanham, Guido; Berkhout, Ben; Kellam, Paul; Reiss, Peter; Fraser, Christophe

2017-06-01

HIV-1 set-point viral load-the approximately stable value of viraemia in the first years of chronic infection-is a strong predictor of clinical outcome and is highly variable across infected individuals. To better understand HIV-1 pathogenesis and the evolution of the viral population, we must quantify the heritability of set-point viral load, which is the fraction of variation in this phenotype attributable to viral genetic variation. However, current estimates of heritability vary widely, from 6% to 59%. Here we used a dataset of 2,028 seroconverters infected between 1985 and 2013 from 5 European countries (Belgium, Switzerland, France, the Netherlands and the United Kingdom) and estimated the heritability of set-point viral load at 31% (CI 15%-43%). Specifically, heritability was measured using models of character evolution describing how viral load evolves on the phylogeny of whole-genome viral sequences. In contrast to previous studies, (i) we measured viral loads using standardized assays on a sample collected in a strict time window of 6 to 24 months after infection, from which the viral genome was also sequenced; (ii) we compared 2 models of character evolution, the classical "Brownian motion" model and another model ("Ornstein-Uhlenbeck") that includes stabilising selection on viral load; (iii) we controlled for covariates, including age and sex, which may inflate estimates of heritability; and (iv) we developed a goodness of fit test based on the correlation of viral loads in cherries of the phylogenetic tree, showing that both models of character evolution fit the data well. An overall heritability of 31% (CI 15%-43%) is consistent with other studies based on regression of viral load in donor-recipient pairs. Thus, about a third of variation in HIV-1 virulence is attributable to viral genetic variation.

B-Plant Canyon Ventilation Control System Description

DOE Office of Scientific and Technical Information (OSTI.GOV)

MCDANIEL, K.S.

1999-08-31

Project W-059 installed a new B Plant Canyon Ventilation System. Monitoring and control of the system is implemented by the Canyon Ventilation Control System (CVCS). This document describes the CVCS system components which include a Programmable Logic Controller (PLC) coupled with an Operator Interface Unit (OIU) and application software. This document also includes an Alarm Index specifying the setpoints and technical basis for system analog and digital alarms.

Manufacturing Research: Self-Directed Control

DTIC Science & Technology

1991-01-01

reduce this sensitivity. SDO is performing Taguchi’s parameter design . 1-13 Statistical Process Control SPC techniques will be used to monitor the process...Florida,R.E. Krieger Pub. Co., 1988. Dehnad, Khowrow, Quality Control . Robust Design . and the Taguchi Method, Pacific Grove, California, Wadsworth... control system. This turns out to be a non -trivial exercise. A human operator can see an event occur (such as the vessel pressurizing above its setpoint

Alternatives for jet engine control

NASA Technical Reports Server (NTRS)

Leake, R. J.; Sain, M. K.

1978-01-01

General goals of the research were classified into two categories. The first category involves the use of modern multivariable frequency domain methods for control of engine models in the neighborhood of a quiescent point. The second category involves the use of nonlinear modelling and optimization techniques for control of engine models over a more extensive part of the flight envelope. In the frequency domain category, works were published in the areas of low-interaction design, polynomial design, and multiple setpoint studies. A number of these ideas progressed to the point at which they are starting to attract practical interest. In the nonlinear category, advances were made both in engine modelling and in the details associated with software for determination of time optimal controls. Nonlinear models for a two spool turbofan engine were expanded and refined; and a promising new approach to automatic model generation was placed under study. A two time scale scheme was developed to do two-dimensional dynamic programming, and an outward spiral sweep technique has greatly speeded convergence times in time optimal calculations.

Control of gravitropic orientation. II. Dual receptor model for gravitropism

NASA Technical Reports Server (NTRS)

LaMotte, Clifford E.; Pickard, Barbara G.

2004-01-01

Gravitropism of vascular plants has been assumed to require a single gravity receptor mechanism. However, based on the evidence in Part I of this study, we propose that maize roots require two. The first mechanism is without a directional effect and, by itself, cannot give rise to tropism. Its role is quantitative facilitation of the second mechanism, which is directional like the gravitational force itself and provides the impetus for tropic curvature. How closely coupled the two mechanisms may be is, as yet, unclear. The evidence for dual receptors supports a general model for roots. When readiness for gravifacilitation, or gravifacilitation itself, is constitutive, orthogravitropic curvature can go to completion. If not constitutively enabled, gravifacilitation can be weak in the absence of light and water deficit or strong in the presence of light and water deficit. In either case, it can decay and permit roots to assume reproducible non-vertical orientations (plagiogravitropic or plagiotropic orientations) without using non-vertical setpoints. In this way roots are deployed in a large volume of soil. Gravitropic behaviours in shoots are more diverse than in roots, utilising oblique and horizontal as well as vertical setpoints. As a guide to future experiments, we assess how constitutive v. non-constitutive modes of gravifacilitation might contribute to behaviours based on each kind of setpoint.

Systems and methods for controlling energy use during a demand limiting period

DOEpatents

Wenzel, Michael J.; Drees, Kirk H.

2016-04-26

Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A feedback controller is used to generate a manipulated variable based on an energy use setpoint and a measured energy use. The manipulated variable may be used for adjusting the operation of an HVAC device.

Supervisory Control System Architecture for Advanced Small Modular Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cetiner, Sacit M; Cole, Daniel L; Fugate, David L

2013-08-01

This technical report was generated as a product of the Supervisory Control for Multi-Modular SMR Plants project within the Instrumentation, Control and Human-Machine Interface technology area under the Advanced Small Modular Reactor (SMR) Research and Development Program of the U.S. Department of Energy. The report documents the definition of strategies, functional elements, and the structural architecture of a supervisory control system for multi-modular advanced SMR (AdvSMR) plants. This research activity advances the state-of-the art by incorporating decision making into the supervisory control system architectural layers through the introduction of a tiered-plant system approach. The report provides a brief history ofmore » hierarchical functional architectures and the current state-of-the-art, describes a reference AdvSMR to show the dependencies between systems, presents a hierarchical structure for supervisory control, indicates the importance of understanding trip setpoints, applies a new theoretic approach for comparing architectures, identifies cyber security controls that should be addressed early in system design, and describes ongoing work to develop system requirements and hardware/software configurations.« less

An alternate protocol to achieve stochastic and deterministic resonances

NASA Astrophysics Data System (ADS)

Tiwari, Ishant; Dave, Darshil; Phogat, Richa; Khera, Neev; Parmananda, P.

2017-10-01

Periodic and Aperiodic Stochastic Resonance (SR) and Deterministic Resonance (DR) are studied in this paper. To check for the ubiquitousness of the phenomena, two unrelated systems, namely, FitzHugh-Nagumo and a particle in a bistable potential well, are studied. Instead of the conventional scenario of noise amplitude (in the case of SR) or chaotic signal amplitude (in the case of DR) variation, a tunable system parameter ("a" in the case of FitzHugh-Nagumo model and the damping coefficient "j" in the bistable model) is regulated. The operating values of these parameters are defined as the "setpoint" of the system throughout the present work. Our results indicate that there exists an optimal value of the setpoint for which maximum information transfer between the input and the output signals takes place. This information transfer from the input sub-threshold signal to the output dynamics is quantified by the normalised cross-correlation coefficient ( | CCC | ). | CCC | as a function of the setpoint exhibits a unimodal variation which is characteristic of SR (or DR). Furthermore, | CCC | is computed for a grid of noise (or chaotic signal) amplitude and setpoint values. The heat map of | CCC | over this grid yields the presence of a resonance region in the noise-setpoint plane for which the maximum enhancement of the input sub-threshold signal is observed. This resonance region could be possibly used to explain how organisms maintain their signal detection efficacy with fluctuating amounts of noise present in their environment. Interestingly, the method of regulating the setpoint without changing the noise amplitude was not able to induce Coherence Resonance (CR). A possible, qualitative reasoning for this is provided.

The Design of Artificial Intelligence Robot Based on Fuzzy Logic Controller Algorithm

NASA Astrophysics Data System (ADS)

Zuhrie, M. S.; Munoto; Hariadi, E.; Muslim, S.

2018-04-01

Artificial Intelligence Robot is a wheeled robot driven by a DC motor that moves along the wall using an ultrasonic sensor as a detector of obstacles. This study uses ultrasonic sensors HC-SR04 to measure the distance between the robot with the wall based ultrasonic wave. This robot uses Fuzzy Logic Controller to adjust the speed of DC motor. When the ultrasonic sensor detects a certain distance, sensor data is processed on ATmega8 then the data goes to ATmega16. From ATmega16, sensor data is calculated based on Fuzzy rules to drive DC motor speed. The program used to adjust the speed of a DC motor is CVAVR program (Code Vision AVR). The readable distance of ultrasonic sensor is 3 cm to 250 cm with response time 0.5 s. Testing of robots on walls with a setpoint value of 9 cm to 10 cm produce an average error value of -12% on the wall of L, -8% on T walls, -8% on U wall, and -1% in square wall.

Individual set-point and gain of emmetropization in chickens.

PubMed

Tepelus, Tudor Cosmin; Schaeffel, Frank

2010-01-01

During the developmental process of emmetropization evidence shows that visual feedback guides the eye as it approaches a refractive state close to zero, or slightly hyperopic. How this "set-point" is internally defined, in the presence of continuous shifts of the focal plane with different viewing distances and accommodation, remains unclear. Minimizing defocus blur over time should produce similar end-point refractions in different individuals. However, we found that individual chickens display considerable variability in their set-point refractive states, despite that they all had the same visual experience. This variability is not random since the refractions in both eyes were highly correlated - even though it is known that they can emmetropize independently. Furthermore, if chicks underwent a period of experimentally induced ametropia, they returned to their individual set-point refractions during recovery (correlation of the refractions before treatment versus after recovery: n=19 chicks, 38 eyes, left eyes: slope 1.01, R=0.860; right eyes: slope 0.85, R=0.610, p<0.001, linear regression). Also, the induced deprivation myopia was correlated in both eyes (n=18 chicks, 36 eyes, p<0.01, orthogonal regression). If chicks were treated with spectacle lenses, the compensatory changes in refraction were, on average, appropriate but individual chicks displayed variable responses. Again, the refractions of both eyes remained correlated (negative lenses, n=18 chicks, 36 eyes, slope 0.89, R=0.504, p<0.01, positive lenses: n=21 chicks, 42 eyes, slope 1.14, R=0.791, p<0.001). The amount of deprivation myopia that developed in two successive treatment cycles, with an intermittent period of recovery, was not correlated; only vitreous chamber growth was almost significantly correlated in both cycles (n=7 chicks, 14 eyes; p<0.05). The amounts of ametropia and vitreous chamber changes induced in two successive cycles of treatment, first with lenses and then with diffusers, were also not correlated, suggesting that the "gains of lens compensation" are different from those in deprivation myopia. In summary, (1) there appears to be an endogenous, possibly genetic, definition of the set-point of emmetropization in each individual, which is similar in both eyes, (2) visual conditions that induce ametropia produce variable changes in refractions, with high correlations between both eyes, (3) overall, the "gain of emmetropization" appears only weakly controlled by endogenous factors.

Systems and methods for controlling energy use in a building management system using energy budgets

DOEpatents

Wenzel, Michael J; Drees, Kirk H

2014-09-23

Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A feedback controller is used to generate a manipulated variable based on an energy use setpoint and a measured energy use. The manipulated variable may be used for adjusting the operation of an HVAC device.

Automatic Strain-Rate Controller,

DTIC Science & Technology

1976-12-01

D—AO37 9~e2 ROME AIR DEVELOPMENT CENTER GRIFFISS AFB N 1’ FIG 13/ 6AUTOMATIC STRAIN—RATE CONTROLLER, (U) DEC 76 R L HUNTSINGER. J A ADAMSK I...goes to zero. CONTROLLER, Leeds and Northrup Series 80 CAT with proportional band , rate , reset, and approach controls . Input from deviation output...8) through ( 16) . (8) Move the set-point slowl y up to 3 or 4. (9) If the recorder po inter hunts , adjust the func t ion controls on tine Ser

Viral genetic variation accounts for a third of variability in HIV-1 set-point viral load in Europe

PubMed Central

Wymant, Chris; Cornelissen, Marion; Gall, Astrid; Bakker, Margreet; Bezemer, Daniela; Hall, Matthew; Hillebregt, Mariska; Ong, Swee Hoe; Albert, Jan; Bannert, Norbert; Fellay, Jacques; Fransen, Katrien; Gourlay, Annabelle J.; Grabowski, M. Kate; Gunsenheimer-Bartmeyer, Barbara; Günthard, Huldrych F.; Kivelä, Pia; Kouyos, Roger; Laeyendecker, Oliver; Liitsola, Kirsi; Meyer, Laurence; Porter, Kholoud; Ristola, Matti; van Sighem, Ard; Vanham, Guido; Berkhout, Ben; Kellam, Paul; Reiss, Peter; Fraser, Christophe

2017-01-01

HIV-1 set-point viral load—the approximately stable value of viraemia in the first years of chronic infection—is a strong predictor of clinical outcome and is highly variable across infected individuals. To better understand HIV-1 pathogenesis and the evolution of the viral population, we must quantify the heritability of set-point viral load, which is the fraction of variation in this phenotype attributable to viral genetic variation. However, current estimates of heritability vary widely, from 6% to 59%. Here we used a dataset of 2,028 seroconverters infected between 1985 and 2013 from 5 European countries (Belgium, Switzerland, France, the Netherlands and the United Kingdom) and estimated the heritability of set-point viral load at 31% (CI 15%–43%). Specifically, heritability was measured using models of character evolution describing how viral load evolves on the phylogeny of whole-genome viral sequences. In contrast to previous studies, (i) we measured viral loads using standardized assays on a sample collected in a strict time window of 6 to 24 months after infection, from which the viral genome was also sequenced; (ii) we compared 2 models of character evolution, the classical “Brownian motion” model and another model (“Ornstein–Uhlenbeck”) that includes stabilising selection on viral load; (iii) we controlled for covariates, including age and sex, which may inflate estimates of heritability; and (iv) we developed a goodness of fit test based on the correlation of viral loads in cherries of the phylogenetic tree, showing that both models of character evolution fit the data well. An overall heritability of 31% (CI 15%–43%) is consistent with other studies based on regression of viral load in donor–recipient pairs. Thus, about a third of variation in HIV-1 virulence is attributable to viral genetic variation. PMID:28604782

40 CFR 1033.140 - Rated power.

Code of Federal Regulations, 2011 CFR

2011-07-01

... value to the nearest whole horsepower. Generally, this will be the brake power of the engine in notch 8... each possible operator demand setpoint or “notch”. See 40 CFR 1065.1001 for the definition of operator... discrete operator demand setpoints, or notches, the nominal power curve would be a series of eight power...

Mitochondrial flashes regulate ATP homeostasis in the heart

PubMed Central

Wang, Xianhua; Zhang, Xing; Wu, Di; Huang, Zhanglong; Hou, Tingting; Jian, Chongshu; Yu, Peng; Lu, Fujian; Zhang, Rufeng; Sun, Tao; Li, Jinghang; Qi, Wenfeng; Wang, Yanru; Gao, Feng; Cheng, Heping

2017-01-01

The maintenance of a constant ATP level (‘set-point’) is a vital homeostatic function shared by eukaryotic cells. In particular, mammalian myocardium exquisitely safeguards its ATP set-point despite 10-fold fluctuations in cardiac workload. However, the exact mechanisms underlying this regulation of ATP homeostasis remain elusive. Here we show mitochondrial flashes (mitoflashes), recently discovered dynamic activity of mitochondria, play an essential role for the auto-regulation of ATP set-point in the heart. Specifically, mitoflashes negatively regulate ATP production in isolated respiring mitochondria and, their activity waxes and wanes to counteract the ATP supply-demand imbalance caused by superfluous substrate and altered workload in cardiomyocytes. Moreover, manipulating mitoflash activity is sufficient to inversely shift the otherwise stable ATP set-point. Mechanistically, the Bcl-xL-regulated proton leakage through F1Fo-ATP synthase appears to mediate the coupling between mitoflash production and ATP set-point regulation. These findings indicate mitoflashes appear to constitute a digital auto-regulator for ATP homeostasis in the heart. DOI: http://dx.doi.org/10.7554/eLife.23908.001 PMID:28692422

The Effect of an Amino Acid Infusion on Central Thermoregulatory Control in Humans

PubMed Central

Nakajima, Yasufumi; Takamata, Akira; Matsukawa, Takashi; Sessler, Daniel I.; Kitamura, Yoshihiro; Ueno, Hiroshi; Tanaka, Yoshifumi; Mizobe, Toshiki

2005-01-01

Background Administration of protein or amino acids enhances thermogenesis, presumably by stimulating oxidative metabolism. However, hyperthermia results even when thermoregulatory responses are intact, suggesting that amino acids also alter central thermoregulatory control. We thus tested the hypothesis that amino acid infusion increases the thermoregulatory setpoint. Methods Nine male volunteers each participated on four study days in randomized order: 1) intravenous amino acids infused at 4 kJ·kg−1·hr−1 for 2.5 h combined with skin-surface warming; 2) amino acid infusion combined with cutaneous cooling; 3) a saline infusion combined with skin-surface warming; and, 4) saline infusion combined with cutaneous cooling. Results Amino acid infusion increased resting core temperature by 0.3 ± 0.1°C (mean ± SD) and oxygen consumption by 18 ± 12%. Furthermore, amino acid infusion increased the calculated core temperature threshold (triggering core temperature at a designated mean-skin temperature of 34°C) for active cutaneous vasodilation by 0.3 ± 0.3°C, for sweating by 0.2 ± 0.2°C, for thermoregulatory vasoconstriction by 0.3 ± 0.3°C, and for thermogenesis by 0.4 ± 0.5°C. Amino acid infusion did not alter the incremental response intensity (i.e., gain) of thermoregulatory defenses. Conclusions Amino acid infusion increased the metabolic rate and resting core temperature. However, amino acids also produced a synchronous increase in all major autonomic thermoregulatory defense thresholds; the increase in core temperature was identical to the setpoint increase — even in a cold environment with amble potential to dissipate heat. In subjects with intact thermoregulatory defenses, amino acid-induced hyperthermia appears to result from an elevated setpoint increase rather than increased metabolic rate per se. PMID:15108979

Proportional plus integral MIMO controller for regulation and tracking with anti-wind-up features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puleston, P.F.; Mantz, R.J.

1993-11-01

A proportional plus integral matrix control structure for MIMO systems is proposed. Based on a standard optimal control structure with integral action, it permits a greater degree of independence of the design and tuning of the regulating and tracking features, without considerably increasing the controller complexity. Fast recovery from load disturbances is achieved, while large overshoots associated with set-point changes and reset wind-up problems can be reduced. A simple effective procedure for practical tuning is introduced.

Feed-Back Moisture Sensor Control for the Delivery of Water to Plants Cultivated in Space

NASA Technical Reports Server (NTRS)

Levine, Howard G.; Prenger, Jessica J.; Rouzan, Donna T.; Spinale, April C.; Murdoch, Trevor; Burtness, Kevin A.

2005-01-01

The development of a spaceflight-rated Porous Tube Insert Module (PTIM) nutrient delivery tray has facilitated a series of studies evaluating various aspects of water and nutrient delivery to plants as they would be cultivated in space. We report here on our first experiment using the PTIM with a software-driven feedback moisture sensor control strategy for maintaining root zone wetness level set-points. One-day-old wheat seedlings (Tritium aestivum cv Apogee; N=15) were inserted into each of three Substrate Compartments (SCs) pre-packed with 0.25-1 . mm Profile(TradeMark) substrate and maintained at root zone relative water content levels of 70, 80 and 90%. The SCs contained a bottom-situated porous tube around which a capillary mat was wrapped. Three Porous Tubes. were planted using similar protocols (but without the substrate) and also maintained at these three moisture level set-points. Half-strength modified Hoagland's nutrient solution was used to supply water and nutrients. Results on hardware performance, water usage rates and wheat developmental differences between the different experimental treatments are presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano

Past works that focused on addressing power-quality and reliability concerns related to renewable energy resources (RESs) operating with business-as-usual practices have looked at the design of Volt/VAr and Volt/Watt strategies to regulate real or reactive powers based on local voltage measurements, so that terminal voltages are within acceptable levels. These control strategies have the potential of operating at the same time scale of distribution-system dynamics, and can therefore mitigate disturbances precipitated fast time-varying loads and ambient conditions; however, they do not necessarily guarantee system-level optimality, and stability claims are mainly based on empirical evidences. On a different time scale, centralizedmore » and distributed optimal power flow (OPF) algorithms have been proposed to compute optimal steady-state inverter setpoints, so that power losses and voltage deviations are minimized and economic benefits to end-users providing ancillary services are maximized. However, traditional OPF schemes may offer decision making capabilities that do not match the dynamics of distribution systems. Particularly, during the time required to collect data from all the nodes of the network (e.g., loads), solve the OPF, and subsequently dispatch setpoints, the underlying load, ambient, and network conditions may have already changed; in this case, the DER output powers would be consistently regulated around outdated setpoints, leading to suboptimal system operation and violation of relevant electrical limits. The present work focuses on the synthesis of distributed RES-inverter controllers that leverage the opportunities for fast feedback offered by power-electronics interfaced RESs. The overarching objective is to bridge the temporal gap between long-term system optimization and real-time control, to enable seamless RES integration in large scale with stability and efficiency guarantees, while congruently pursuing system-level optimization objectives. The design of the control framework is based on suitable linear approximations of the AC power-flow equations as well as Lagrangian regularization methods. The proposed controllers enable an update of the power outputs at a time scale that is compatible with the underlying dynamics of loads and ambient conditions, and continuously drive the system operation towards OPF-based solutions.« less

76 FR 30206 - Southern Nuclear Operating Company, Inc., Vogtle Electric Generating Plant, Unit 1 and 2; Notice...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-24

... High-High, Nominal Trip Setpoint (NTSP) and Allowable Value. The Steam Generator Water Level High-High... previously evaluated is not increased. The Steam Generator Water Level High-High function revised values..., Steam Generator Water Level High-High, Nominal Trip Setpoint (NTSP) and Allowable Value. Function 5c...

Towards a framework for selection of supervisory control for commercial buildings: HVAC system energy efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramachandran, Thiagarajan; Kundu, Soumya; Chen, Yan

This paper develops and utilizes an optimization based framework to investigate the maximal energy efficiency potentially attainable by HVAC system operation in a non-predictive context. Performance is evaluated relative to the existing state of the art set-point reset strategies. The expected efficiency increase driven by operation constraints relaxations is evaluated.

Real-time plasma control in a dual-frequency, confined plasma etcher

NASA Astrophysics Data System (ADS)

Milosavljević, V.; Ellingboe, A. R.; Gaman, C.; Ringwood, J. V.

2008-04-01

The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O2 flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor signals onto the control inputs, allowing compensation of the interaction between control paths. The compensated sensor signals and compensated set-points are then used as inputs to proportional-integral-derivative controllers to adjust radio frequency power and oxygen flow to yield the desired ion flux and chemical density. To illustrate the methodology, model-based real-time control is realized in a commercial semiconductor dielectric etch chamber. The two radio frequency symmetric diode operates with typical commercial fluorocarbon feed-gas mixtures (Ar/O2/C4F8). Key parameters for dielectric etching are known to include ion flux to the surface and surface flux of oxygen containing species. Control is demonstrated using diagnostics of electrode-surface ion current, and chemical densities of O, O2, and CO measured by optical emission spectrometry and/or mass spectrometry. Using our model-based real-time control, the set-point tracking accuracy to changes in chemical species density and ion flux is enhanced.

Electronic field permeameter

DOEpatents

Chandler, Mark A.; Goggin, David J.; Horne, Patrick J.; Kocurek, Gary G.; Lake, Larry W.

1989-01-01

For making rapid, non-destructive permeability measurements in the field, a portable minipermeameter of the kind having a manually-operated gas injection tip is provided with a microcomputer system which operates a flow controller to precisely regulate gas flow rate to a test sample, and reads a pressure sensor which senses the pressure across the test sample. The microcomputer system automatically turns on the gas supply at the start of each measurement, senses when a steady-state is reached, collects and records pressure and flow rate data, and shuts off the gas supply immediately after the measurement is completed. Preferably temperature is also sensed to correct for changes in gas viscosity. The microcomputer system may also provide automatic zero-point adjustment, sensor calibration, over-range sensing, and may select controllers, sensors, and set-points for obtaining the most precise measurements. Electronic sensors may provide increased accuracy and precision. Preferably one microcomputer is used for sensing instrument control and data collection, and a second microcomputer is used which is dedicated to recording and processing the data, selecting the sensors and set-points for obtaining the most precise measurements, and instructing the user how to set-up and operate the minipermeameter. To provide mass data collection and user-friendly operation, the second microcomputer is preferably a lap-type portable microcomputer having a non-volatile or battery-backed CMOS memory.

Model Predictive Control of HVAC Systems: Implementation and Testing at the University of California, Merced

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haves, Phillip; Hencey, Brandon; Borrell, Francesco

2010-06-29

A Model Predictive Control algorithm was developed for the UC Merced campus chilled water plant. Model predictive control (MPC) is an advanced control technology that has proven successful in the chemical process industry and other industries. The main goal of the research was to demonstrate the practical and commercial viability of MPC for optimization of building energy systems. The control algorithms were developed and implemented in MATLAB, allowing for rapid development, performance, and robustness assessment. The UC Merced chilled water plant includes three water-cooled chillers and a two million gallon chilled water storage tank. The tank is charged during themore » night to minimize on-peak electricity consumption and take advantage of the lower ambient wet bulb temperature. The control algorithms determined the optimal chilled water plant operation including chilled water supply (CHWS) temperature set-point, condenser water supply (CWS) temperature set-point and the charging start and stop times to minimize a cost function that includes energy consumption and peak electrical demand over a 3-day prediction horizon. A detailed model of the chilled water plant and simplified models of the buildings served by the plant were developed using the equation-based modeling language Modelica. Steady state models of the chillers, cooling towers and pumps were developed, based on manufacturers performance data, and calibrated using measured data collected and archived by the control system. A detailed dynamic model of the chilled water storage tank was also developed and calibrated. Simple, semi-empirical models were developed to predict the temperature and flow rate of the chilled water returning to the plant from the buildings. These models were then combined and simplified for use in a model predictive control algorithm that determines the optimal chiller start and stop times and set-points for the condenser water temperature and the chilled water supply temperature. The report describes the development and testing of the algorithm and evaluates the resulting performance, concluding with a discussion of next steps in further research. The experimental results show a small improvement in COP over the baseline policy but it is difficult to draw any strong conclusions about the energy savings potential for MPC with this system only four days of suitable experimental data were obtained once correct operation of the MPC system had been achieved. These data show an improvement in COP of 3.1% {+-} 2.2% relative to a baseline established immediately prior to the period when the MPC was run in its final form. This baseline includes control policy improvements that the plant operators learned by observing the earlier implementations of MPC, including increasing the temperature of the water supplied to the chiller condensers from the cooling towers. The process of data collection and model development, necessary for any MPC project, resulted in the team uncovering various problems with the chilled water system. Although it is difficult to quantify the energy savings resulting from these problems being remedied, they were likely on the same order as the energy savings from the MPC itself. Although the types of problems uncovered and the level of energy savings may differ significantly from other projects, some of the benefits of detecting and diagnosing problems are expected from the use of MPC for any chilled water plant. The degree of chiller loading was found to be a key factor for efficiency. It is more efficient to operate the chillers at or near full load. In order to maximize the chiller load, one would maximize the temperature difference across chillers and the chilled water flow rate through the chillers. Thus, the CHWS set-point and the chilled water flow-rate can be used to limit the chiller loading to prevent chiller surging. Since the flow rate has an upper bound and the CHWS set point has a lower bound, the chiller loading is constrained and often determined by the chilled water return temperature (CHWR). The CHWR temperature is primarily comprised of warm water from the top of the TES tank. The CHWR temperature falls substantially as the thermocline approaches the top of the tank, which reduces the chiller loading. As a result, it has been determined that overcharging the TES tank can be detrimental to the chilled water plant efficiency. The resulting MPC policy differs from the current practice of fully charging the TES tank. A heuristic rule could possible avoid this problem without using predictive control. Similarly, the COP improvements from the change in CWS set-point were largely captured by a static set-point change by the operators. Further research is required to determine how much of the MPC savings could be garnered through simplified rules (based on the MPC study), with and without prediction.« less

Comparative study of control strategies for hybrid GSHP system in the cooling dominated climate

DOE PAGES

Wang, Shaojie; Liu, Xiaobing; Gates, Steve

2015-01-06

The ground source heat pump (GSHP) system is one of the most energy efficient HVAC technologies in the current market. However, the heat imbalance may degrade the ability of the ground loop heat exchanger (GLHX) to absorb or reject heat. The hybrid GSHP system, which combines a geothermal well field with a supplemental boiler or cooling tower, can balance the loads imposed on the ground loop heat exchangers to minimize its size while retaining superior energy efficiency. This paper presents a recent simulation-based study with an intention to compare multiple common control strategies used in hybrid GSHP systems, including fixedmore » setpoint, outside air reset, load reset, and wetbulb reset. A small office in Oklahoma City conditioned by a hybrid GSHP system was simulated with the latest version of eQUEST 3.7 [1]. In the end, the simulation results reveal that the hybrid GSHP system has the excellent capability to meet the cooling and heating setpoints during the occupied hours, balance thermal loads on the ground loop, as well as improve the thermal comfort of the occupants with the reduced size well field.« less

An Improved Formulation of Hybrid Model Predictive Control With Application to Production-Inventory Systems.

PubMed

Nandola, Naresh N; Rivera, Daniel E

2013-01-01

We consider an improved model predictive control (MPC) formulation for linear hybrid systems described by mixed logical dynamical (MLD) models. The algorithm relies on a multiple-degree-of-freedom parametrization that enables the user to adjust the speed of setpoint tracking, measured disturbance rejection and unmeasured disturbance rejection independently in the closed-loop system. Consequently, controller tuning is more flexible and intuitive than relying on objective function weights (such as move suppression) traditionally used in MPC schemes. The controller formulation is motivated by the needs of non-traditional control applications that are suitably described by hybrid production-inventory systems. Two applications are considered in this paper: adaptive, time-varying interventions in behavioral health, and inventory management in supply chains under conditions of limited capacity. In the adaptive intervention application, a hypothetical intervention inspired by the Fast Track program, a real-life preventive intervention for reducing conduct disorder in at-risk children, is examined. In the inventory management application, the ability of the algorithm to judiciously alter production capacity under conditions of varying demand is presented. These case studies demonstrate that MPC for hybrid systems can be tuned for desired performance under demanding conditions involving noise and uncertainty.

An Improved Formulation of Hybrid Model Predictive Control With Application to Production-Inventory Systems

PubMed Central

Nandola, Naresh N.; Rivera, Daniel E.

2013-01-01

We consider an improved model predictive control (MPC) formulation for linear hybrid systems described by mixed logical dynamical (MLD) models. The algorithm relies on a multiple-degree-of-freedom parametrization that enables the user to adjust the speed of setpoint tracking, measured disturbance rejection and unmeasured disturbance rejection independently in the closed-loop system. Consequently, controller tuning is more flexible and intuitive than relying on objective function weights (such as move suppression) traditionally used in MPC schemes. The controller formulation is motivated by the needs of non-traditional control applications that are suitably described by hybrid production-inventory systems. Two applications are considered in this paper: adaptive, time-varying interventions in behavioral health, and inventory management in supply chains under conditions of limited capacity. In the adaptive intervention application, a hypothetical intervention inspired by the Fast Track program, a real-life preventive intervention for reducing conduct disorder in at-risk children, is examined. In the inventory management application, the ability of the algorithm to judiciously alter production capacity under conditions of varying demand is presented. These case studies demonstrate that MPC for hybrid systems can be tuned for desired performance under demanding conditions involving noise and uncertainty. PMID:24348004

Tensiometer-Based Irrigation Management of Subirrigated Soilless Tomato: Effects of Substrate Matric Potential Control on Crop Performance

PubMed Central

Montesano, Francesco F.; Serio, Francesco; Mininni, Carlo; Signore, Angelo; Parente, Angelo; Santamaria, Pietro

2015-01-01

Automatic irrigation scheduling based on real-time measurement of soilless substrate water status has been recognized as a promising approach for efficient greenhouse irrigation management. Identification of proper irrigation set points is crucial for optimal crop performance, both in terms of yield and quality, and optimal use of water resources. The objective of the present study was to determine the effects of irrigation management based on matric potential control on growth, plant–water relations, yield, fruit quality traits, and water-use efficiency of subirrigated (through bench system) soilless tomato. Tensiometers were used for automatic irrigation control. Two cultivars, “Kabiria” (cocktail type) and “Diana” (intermediate type), and substrate water potential set-points (−30 and −60 hPa, for “Diana,” and −30, −60, and −90 hPa for “Kabiria”), were compared. Compared with −30 hPa, water stress (corresponding to a −60 hPa irrigation set-point) reduced water consumption (14%), leaf area (18%), specific leaf area (19%), total yield (10%), and mean fruit weight (13%), irrespective of the cultivars. At −60 hPa, leaf-water status of plants, irrespective of the cultivars, showed an osmotic adjustment corresponding to a 9% average osmotic potential decrease. Total yield, mean fruit weight, plant water, and osmotic potential decreased linearly when −30, −60, and −90 hPa irrigation set-points were used in “Kabiria.” Unmarketable yield in “Diana” increased when water stress was imposed (187 vs. 349 g·plant−1, respectively, at −30 and −60 hPa), whereas the opposite effect was observed in “Kabiria,” where marketable yield loss decreased linearly [by 1.05 g·plant−1 per unit of substrate water potential (in the tested range from −30 to −90 hPa)]. In the second cluster, total soluble solids of the fruit and dry matter increased irrespective of the cultivars. In the seventh cluster, in “Diana,” only a slight increase was observed from −30 vs. −60 hPa (3.3 and 1.3%, respectively, for TSS and dry matter), whereas in “Kabiria,” the increase was more pronounced (8.7 and 12.0%, respectively, for TSS and dry matter), and further reduction in matric potential from −60 to −90 hPa confirmed the linear increase for both parameters. Both glucose and fructose concentrations increased linearly in “Kabiria” fruits on decreasing the substrate matric potential, whereas in “Diana,” there was no increase. It is feasible to act on matric potential irrigation set-points to control plant response in terms of fruit quality parameters. Precise control of substrate water status may offer the possibility to steer crop response by enhancing different crop-performance components, namely yield and fruit quality, in subirrigated tomato. Small-sized fruit varieties benefit more from controlled water stress in terms of reduced unmarketable yield loss and fruit quality improvements. PMID:26779189

Effects of a PID Control System on Electromagnetic Fields in an nEDM Experiment

NASA Astrophysics Data System (ADS)

Molina, Daniel

2017-09-01

The Kellogg Radiation Laboratory is currently testing a prototype for an experiment that hopes to identify the electric dipole moment of the neutron. As part of this testing, we have developed a PID (proportional, integral, derivative) feedback system that uses large coils to fix the value of local external magnetic fields, up to linear gradients. PID algorithms compare the current value to a set-point and use the integral and derivative of the field with respect to the set-point to maintain constant fields. We have also developed a method for zeroing linear gradients within the experimental apparatus. In order to determine the performance of the PID algorithm, measurements of both the internal and external fields were obtained with and without the algorithm running, and these results were compared for noise and time stability. We have seen that the PID algorithm can reduce the effect of disturbance to the field by a factor of 10.

Obesity Energetics: Body Weight Regulation and the Effects of Diet Composition

PubMed Central

Hall, Kevin D.; Guo, Juen

2017-01-01

Weight changes are accompanied by imbalances between calorie intake and expenditure. This fact is often misinterpreted to suggest that obesity is caused by gluttony and sloth and can be treated by simply advising people to eat less and move more. However, various components of energy balance are dynamically interrelated and weight loss is resisted by counterbalancing physiological processes. While low-carbohydrate diets have been suggested to partially subvert these processes by increasing energy expenditure and promoting fat loss, our meta-analysis of 32 controlled feeding studies with isocaloric substitution of carbohydrate for fat found that both energy expenditure (26 kcal/d; P <.0001) and fat loss (16 g/d; P <.0001) were greater with lower fat diets. We review the components of energy balance and the mechanisms acting to resist weight loss in the context of static, settling point, and set-point models of body weight regulation, with the set-point model being most commensurate with current data. PMID:28193517

AZ-101 Mixer Pump Test Qualification Test Procedures (QTP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

THOMAS, W.K.

2000-01-10

Describes the Qualification test procedure for the AZ-101 Mixer Pump Data Acquisition System (DAS). The purpose of this Qualification Test Procedure (QTP) is to confirm that the AZ-101 Mixer Pump System has been properly programmed and hardware configured correctly. This QTP will test the software setpoints for the alarms and also check the wiring configuration from the SIMcart to the HMI. An Acceptance Test Procedure (ATP), similar to this QTP will be performed to test field devices and connections from the field.

Scenario-based, closed-loop model predictive control with application to emergency vehicle scheduling

NASA Astrophysics Data System (ADS)

Goodwin, Graham. C.; Medioli, Adrian. M.

2013-08-01

Model predictive control has been a major success story in process control. More recently, the methodology has been used in other contexts, including automotive engine control, power electronics and telecommunications. Most applications focus on set-point tracking and use single-sequence optimisation. Here we consider an alternative class of problems motivated by the scheduling of emergency vehicles. Here disturbances are the dominant feature. We develop a novel closed-loop model predictive control strategy aimed at this class of problems. We motivate, and illustrate, the ideas via the problem of fluid deployment of ambulance resources.

Software design to calculate and simulate the mechanical response of electromechanical lifts

NASA Astrophysics Data System (ADS)

Herrera, I.; Romero, E.

2016-05-01

Lift engineers and lift companies which are involved in the design process of new products or in the research and development of improved components demand a predictive tool of the lift slender system response before testing expensive prototypes. A method for solving the movement of any specified lift system by means of a computer program is presented. The mechanical response of the lift operating in a user defined installation and configuration, for a given excitation and other configuration parameters of real electric motors and its control system, is derived. A mechanical model with 6 degrees of freedom is used. The governing equations are integrated step by step through the Meden-Kutta algorithm in the MATLAB platform. Input data consists on the set point speed for a standard trip and the control parameters of a number of controllers and lift drive machines. The computer program computes and plots very accurately the vertical displacement, velocity, instantaneous acceleration and jerk time histories of the car, counterweight, frame, passengers/loads and lift drive in a standard trip between any two floors of the desired installation. The resulting torque, rope tension and deviation of the velocity plot with respect to the setpoint speed are shown. The software design is implemented in a demo release of the computer program called ElevaCAD. Further on, the program offers the possibility to select the configuration of the lift system and the performance parameters of each component. In addition to the overall system response, detailed information of transients, vibrations of the lift components, ride quality levels, modal analysis and frequency spectrum (FFT) are plotted.

Controlling Wind Turbines for Secondary Frequency Regulation: An Analysis of AGC Capabilities Under New Performance Based Compensation Policy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aho, Jacob; Pao, Lucy Y.; Fleming, Paul

2014-11-13

As wind energy becomes a larger portion of the world's energy portfolio there has been an increased interest for wind turbines to control their active power output to provide ancillary services which support grid reliability. One of these ancillary services is the provision of frequency regulation, also referred to as secondary frequency control or automatic generation control (AGC), which is often procured through markets which recently adopted performance-based compensation. A wind turbine with a control system developed to provide active power ancillary services can be used to provide frequency regulation services. Simulations have been performed to determine the AGC trackingmore » performance at various power schedule set-points, participation levels, and wind conditions. The performance metrics used in this study are based on those used by several system operators in the US. Another metric that is analyzed is the damage equivalent loads (DELs) on turbine structural components, though the impacts on the turbine electrical components are not considered. The results of these single-turbine simulations show that high performance scores can be achieved when there are insufficient wind resources available. The capability of a wind turbine to rapidly and accurately follow power commands allows for high performance even when tracking rapidly changing AGC signals. As the turbine de-rates to meet decreased power schedule set-points there is a reduction in the DELs, and the participation in frequency regulation has a negligible impact on these loads.« less

Predictions of Energy Savings in HVAC Systems by Lumped Models (Preprint)

DTIC Science & Technology

2010-04-14

various control devices into a simulated HVAC system. Con- trols contain a setpoint of 26.7oC. The adjustable damper, variable chiller work input, and variable fanspeed contain values of αP of -1.0, 0.1, and 1.0, respectively. 25 ...Villanova, PA 19085 bCode 985, Naval System Warfare Center, Carderock Division, Philadelphia, PA 19112 Abstract An approach to optimizing the energy...suggest an order of mag- nitude greater energy savings using a variable chiller power control approach compared to control damper and variable-drive

Investigation of energy management strategies for photovoltaic systems - A predictive control algorithm

NASA Technical Reports Server (NTRS)

Cull, R. C.; Eltimsahy, A. H.

1983-01-01

The present investigation is concerned with the formulation of energy management strategies for stand-alone photovoltaic (PV) systems, taking into account a basic control algorithm for a possible predictive, (and adaptive) controller. The control system controls the flow of energy in the system according to the amount of energy available, and predicts the appropriate control set-points based on the energy (insolation) available by using an appropriate system model. Aspects of adaptation to the conditions of the system are also considered. Attention is given to a statistical analysis technique, the analysis inputs, the analysis procedure, and details regarding the basic control algorithm.

Superior Control of HIV-1 Replication by CD8+ T Cells Targeting Conserved Epitopes: Implications for HIV Vaccine Design

PubMed Central

Kunwar, Pratima; Hawkins, Natalie; Dinges, Warren L.; Liu, Yi; Gabriel, Erin E.; Swan, David A.; Stevens, Claire E.; Maenza, Janine; Collier, Ann C.; Mullins, James I.; Hertz, Tomer; Yu, Xuesong; Horton, Helen

2013-01-01

A successful HIV vaccine will likely induce both humoral and cell-mediated immunity, however, the enormous diversity of HIV has hampered the development of a vaccine that effectively elicits both arms of the adaptive immune response. To tackle the problem of viral diversity, T cell-based vaccine approaches have focused on two main strategies (i) increasing the breadth of vaccine-induced responses or (ii) increasing vaccine-induced responses targeting only conserved regions of the virus. The relative extent to which set-point viremia is impacted by epitope-conservation of CD8+ T cell responses elicited during early HIV-infection is unknown but has important implications for vaccine design. To address this question, we comprehensively mapped HIV-1 CD8+ T cell epitope-specificities in 23 ART-naïve individuals during early infection and computed their conservation score (CS) by three different methods (prevalence, entropy and conseq) on clade-B and group-M sequence alignments. The majority of CD8+ T cell responses were directed against variable epitopes (p<0.01). Interestingly, increasing breadth of CD8+ T cell responses specifically recognizing conserved epitopes was associated with lower set-point viremia (r = - 0.65, p = 0.009). Moreover, subjects possessing CD8+ T cells recognizing at least one conserved epitope had 1.4 log10 lower set-point viremia compared to those recognizing only variable epitopes (p = 0.021). The association between viral control and the breadth of conserved CD8+ T cell responses may be influenced by the method of CS definition and sequences used to determine conservation levels. Strikingly, targeting variable versus conserved epitopes was independent of HLA type (p = 0.215). The associations with viral control were independent of functional avidity of CD8+ T cell responses elicited during early infection. Taken together, these data suggest that the next-generation of T-cell based HIV-1 vaccines should focus on strategies that can elicit CD8+ T cell responses to multiple conserved epitopes of HIV-1. PMID:23741326

Actively controlled shaft seals for aerospace applications

NASA Technical Reports Server (NTRS)

Salant, Richard F.

1994-01-01

This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100 C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changed suddenly.

Fundamentals of SCADA and automated meter reading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwok, A.

1992-02-01

This paper discusses SCADA systems allow users to control and acquire data from remote facilities such as compressors, pressure-regulating stations, control valves and measurement stations. In general, a SCADA system performs functions in sequential control, continuous control, supervisory setpoint control and data acquisitions. AMR systems allow users to obtain up-to-date information on their gas demand. When AMR was in its infancy, equipment was designed only to read and record gas consumption values. The basic function of an early AMR system was to read gas volume at a fixed interval and record the data in its memory until it communicated withmore » a central receiving facility.« less

Demand response-enabled model predictive HVAC load control in buildings using real-time electricity pricing

NASA Astrophysics Data System (ADS)

Avci, Mesut

A practical cost and energy efficient model predictive control (MPC) strategy is proposed for HVAC load control under dynamic real-time electricity pricing. The MPC strategy is built based on a proposed model that jointly minimizes the total energy consumption and hence, cost of electricity for the user, and the deviation of the inside temperature from the consumer's preference. An algorithm that assigns temperature set-points (reference temperatures) to price ranges based on the consumer's discomfort tolerance index is developed. A practical parameter prediction model is also designed for mapping between the HVAC load and the inside temperature. The prediction model and the produced temperature set-points are integrated as inputs into the MPC controller, which is then used to generate signal actions for the AC unit. To investigate and demonstrate the effectiveness of the proposed approach, a simulation based experimental analysis is presented using real-life pricing data. An actual prototype for the proposed HVAC load control strategy is then built and a series of prototype experiments are conducted similar to the simulation studies. The experiments reveal that the MPC strategy can lead to significant reductions in overall energy consumption and cost savings for the consumer. Results suggest that by providing an efficient response strategy for the consumers, the proposed MPC strategy can enable the utility providers to adopt efficient demand management policies using real-time pricing. Finally, a cost-benefit analysis is performed to display the economic feasibility of implementing such a controller as part of a building energy management system, and the payback period is identified considering cost of prototype build and cost savings to help the adoption of this controller in the building HVAC control industry.

Feedforward/feedback control synthesis for performance and robustness

NASA Technical Reports Server (NTRS)

Wie, Bong; Liu, Qiang

1990-01-01

Both feedforward and feedback control approaches for uncertain dynamical systems are investigated. The control design objective is to achieve a fast settling time (high performance) and robustness (insensitivity) to plant modeling uncertainty. Preshapong of an ideal, time-optimal control input using a 'tapped-delay' filter is shown to provide a rapid maneuver with robust performance. A robust, non-minimum-phase feedback controller is synthesized with particular emphasis on its proper implementation for a non-zero set-point control problem. The proposed feedforward/feedback control approach is robust for a certain class of uncertain dynamical systems, since the control input command computed for a given desired output does not depend on the plant parameters.

Temporal heating profile influence on the immediate bond strength following laser tissue soldering.

PubMed

Rabi, Yaron; Katzir, Abraham

2010-07-01

Bonding of tissues by laser heating is considered as a future alternative to sutures and staples. Increasing the post-operative bond strength remains a challenging issue for laser tissue bonding, especially in organs that have to sustain considerable tension or pressure. In this study, we investigated the influence of different temporal heating profiles on the strength of soldered incisions. The thermal damage following each heating procedure was quantified, in order to assess the effect of each heating profile on the thermal damage. Incisions in porcine bowel tissue strips (1 cmx4 cm) were soldered, using a 44% liquid albumin mixed with indocyanine green and a temperature controlled laser (830 nm) tissue bonding system. Heating was done either with a linear or a step temporal heating profile. The incisions were bonded by soldering at three points, separated by 2 mm. Set-point temperatures of T(set) = 60, 70, 80, 90, 100, 110, 150 degrees C and dwell times of t(d) = 10, 20, 30, 40 seconds were investigated. The bond strength was measured immediately following each soldering by applying a gradually increased tension on the tissue edges until the bond break. Bonds formed by linear heating were stronger than the ones formed by step heating: at T(set) = 80 degrees C the bonds were 40% stronger and at T(set) = 90 degrees C the bonds strength was nearly doubled. The bond strength difference between the heating methods was larger as T(set) increased. Linear heating produced stronger bonds than step heating. The difference in the bond strength was more pronounced at high set-point temperatures and short dwell times. The bond strength could be increased with either higher set-point temperature or a longer dwell time.

Electromechanical analogs of human reflexes.

PubMed

Littman, M G; Liker, M; Stubbeman, W; Russakow, J; McGee, C; Gelfand, J; Call, B J

1989-01-01

The conclusion to be drawn from our modeling is that the combined stretch and tendon reflexes alone can endow artificial muscle with a springlike feel as well as give it a baseline tone. In response to questions that motor physiologists often ask as to what variables the system controls, the answer here is clear: the stretch and tendon reflexes act together to maintain both a tension set-point and a length set-point, but in so doing they also give the system a springlike feel because of the existence of a servo error. The main goal of our studies is to understand the integration of reflexes, and thus far we have only begun to explore the two lowest-level spinal reflexes. We are in the process of expanding this work by developing a much more refined arm explicitly modeled after the human arm. This new arm is to be activated by a minimum of 10 muscles, each of which is reflexively driven, and it will allow us to explore the integration of higher-level reflex action such as automatic inhibition of antagonists and facilitation of synergists.

Direct manipulation of metallic nanosheets by shear force microscopy.

PubMed

Bi, Z; Cai, W; Wang, Y; Shang, G

2018-05-15

Micro/nanomanipulation is a rapidly growing technology and holds promising applications in various fields, including photonic/electronic devices, chemical/biosensors etc. In this work, we present that shear force microscopy (ShFM) can be exploited to manipulate metallic nanosheets besides imaging. The manipulation is realized via controlling the shear force sensor probe position and shear force magnitude based on our homemade ShFM system under an optical microscopy for in situ observation. The main feature of the ShFM system is usage of a piezoelectric bimorph sensor, which has the ability of self-excitation and detection. Moreover, the shear force magnitude as a function of the spring constant of the sensor and setpoint is obtained, which indicates that operation modes can be switched between imaging and manipulation through designing the spring constant before experiment and changing the setpoint during manipulation process, respectively. We believe that this alternative manipulation technique could be used to assemble other nanostructures with different shapes, sizes and compositions for new properties and wider applications. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

GUI for Computational Simulation of a Propellant Mixer

NASA Technical Reports Server (NTRS)

Figueroa, Fernando; Richter, Hanz; Barbieri, Enrique; Granger, Jamie

2005-01-01

Control Panel is a computer program that generates a graphical user interface (GUI) for computational simulation of a rocket-test-stand propellant mixer in which gaseous hydrogen (GH2) is injected into flowing liquid hydrogen (LH2) to obtain a combined flow having desired thermodynamic properties. The GUI is used in conjunction with software that models the mixer as a system having three inputs (the positions of the GH2 and LH2 inlet valves and an outlet valve) and three outputs (the pressure inside the mixer and the outlet flow temperature and flow rate). The user can specify valve characteristics and thermodynamic properties of the input fluids via userfriendly dialog boxes. The user can enter temporally varying input values or temporally varying desired output values. The GUI provides (1) a set-point calculator function for determining fixed valve positions that yield desired output values and (2) simulation functions that predict the response of the mixer to variations in the properties of the LH2 and GH2 and manual- or feedback-control variations in valve positions. The GUI enables scheduling of a sequence of operations that includes switching from manual to feedback control when a certain event occurs.

Crystal Growth Control

NASA Technical Reports Server (NTRS)

Duval, Walter M. B.; Batur, Celal; Bennett, Robert J.

1997-01-01

We present an innovative design of a vertical transparent multizone furnace which can operate in the temperature range of 25 C to 750 C and deliver thermal gradients of 2 C/cm to 45 C/cm for the commercial applications to crystal growth. The operation of the eight zone furnace is based on a self-tuning temperature control system with a DC power supply for optimal thermal stability. We show that the desired thermal profile over the entire length of the furnace consists of a functional combination of the fundamental thermal profiles for each individual zone obtained by setting the set-point temperature for that zone. The self-tuning system accounts for the zone to zone thermal interactions. The control system operates such that the thermal profile is maintained under thermal load, thus boundary conditions on crystal growth ampoules can be predetermined prior to crystal growth. Temperature profiles for the growth of crystals via directional solidification, vapor transport techniques, and multiple gradient applications are shown to be easily implemented. The unique feature of its transparency and ease of programming thermal profiles make the furnace useful for scientific and commercial applications for the determination of process parameters to optimize crystal growth conditions.

Improved spectrophotometric cell for hydrothermal solutions

USGS Publications Warehouse

Susak, N.J.; Crerar, D.A.; Forseman, T.C.; Haas, J.L.

1981-01-01

A simple, inexpensive spectrophotometric cell was designed for use with aqueous solutions for which temperature is a maximum of 325??C and pressure, 28 MPa. The cell has an internal volume of 5 ml and a path length of 1.31 cm. Each furnace assembly is 120 mm in diameter ?? 150 mm high and will fit into most commercial spectrophotometers. Temperature is controlled by a standard set-point controller and a balancing circuit that is used to maintain the temperature of the sample and reference cell within 1??C of each other at any temperature.

Monitoring System and Temperature Controlling on PID Based Poultry Hatching Incubator

NASA Astrophysics Data System (ADS)

Shafiudin, S.; Kholis, N.

2018-04-01

Poultry hatching cultivation is essential to be observed in terms of temperature stability by using artificial penetration incubator which applies On/Off control. The On/Off control produces relatively long response time to reach steady-state conditions. Moreover, how the system works makes the component worn out because the lamp is on-off periodically. Besides, the cultivation in the market is less suitable to be used in an environment which has fluctuating temperature because it may influence plant’s temperature stability. The study aims to design automatic poultry hatching cultivation that can repair the temperature’s response of plant incubator to keep stable and in line with the intended set-point temperature value by using PID controller. The method used in PID controlling is designed to identify plant using ARX (Auto Regressive eXogenous) MATLAB which is dynamic/non-linear to obtain mathematical model and PID constants value that is appropriate to system. The hardware design for PID-based egg incubator uses Arduino Uno R3, as the main controller that includes PID source, and PWM, to keep plant temperature stability, which is integrated with incandescent light actuators and sensors where DHTI 1 sensor as the reader as temperature condition and plant humidity. The result of the study showed that PID constants value of each plant is different. For parallel 15 Watt plant, Kp = 3.9956, Ki = 0.361, Kd = 0, while for parallel 25 Watt plant, the value of Kp = 5.714, Ki = 0.351, Kd = 0. The PID constants value were capable to produce stable system response which is based on set-point with steady state error’s value is around 5%, that is 2.7%. With hatching percentage of 70-80%, the hatching process is successful in air-conditioned environment (changeable).

Conversion and control of an all-terrain vehicle for use as an autonomous mobile robot

NASA Astrophysics Data System (ADS)

Jacob, John S.; Gunderson, Robert W.; Fullmer, R. R.

1998-08-01

A systematic approach to ground vehicle automation is presented, combining low-level controls, trajectory generation and closed-loop path correction in an integrated system. Development of cooperative robotics for precision agriculture at Utah State University required the automation of a full-scale motorized vehicle. The Triton Predator 8- wheeled skid-steering all-terrain vehicle was selected for the project based on its ability to maneuver precisely and the simplicity of controlling the hydrostatic drivetrain. Low-level control was achieved by fitting an actuator on the engine throttle, actuators for the left and right drive controls, encoders on the left and right drive shafts to measure wheel speeds, and a signal pick-off on the alternator for measuring engine speed. Closed loop control maintains a desired engine speed and tracks left and right wheel speeds commands. A trajectory generator produces the wheel speed commands needed to steer the vehicle through a predetermined set of map coordinates. A planar trajectory through the points is computed by fitting a 2D cubic spline over each path segment while enforcing initial and final orientation constraints at segment endpoints. Acceleration and velocity profiles are computed for each trajectory segment, with the velocity over each segment dependent on turning radius. Left and right wheel speed setpoints are obtained by combining velocity and path curvature for each low-level timestep. The path correction algorithm uses GPS position and compass orientation information to adjust the wheel speed setpoints according to the 'crosstrack' and 'downtrack' errors and heading error. Nonlinear models of the engine and the skid-steering vehicle/ground interaction were developed for testing the integrated system in simulation. These test lead to several key design improvements which assisted final implementation on the vehicle.

Availability of activated CD4+ T cells dictates the level of viremia in naturally SIV-infected sooty mangabeys.

PubMed

Klatt, Nichole R; Villinger, Francois; Bostik, Pavel; Gordon, Shari N; Pereira, Lara; Engram, Jessica C; Mayne, Ann; Dunham, Richard M; Lawson, Benton; Ratcliffe, Sarah J; Sodora, Donald L; Else, James; Reimann, Keith; Staprans, Silvija I; Haase, Ashley T; Estes, Jacob D; Silvestri, Guido; Ansari, Aftab A

2008-06-01

Naturally SIV-infected sooty mangabeys (SMs) remain asymptomatic despite high virus replication. Elucidating the mechanisms underlying AIDS resistance of SIV-infected SMs may provide crucial information to better understand AIDS pathogenesis. In this study, we assessed the determinants of set-point viremia in naturally SIV-infected SMs, i.e., immune control of SIV replication versus target cell limitation. We depleted CD4+ T cells in 6 naturally SIV-infected SMs by treating with humanized anti-CD4 mAb (Cdr-OKT4A-huIgG1). CD4+ T cells were depleted almost completely in blood and BM and at variable levels in mucosal tissues and LNs. No marked depletion of CD14+ monocytes was observed. Importantly, CD4+ T cell depletion was associated with a rapid, significant decline in viral load, which returned to baseline level at day 30-45, coincident with an increased fraction of proliferating and activated CD4+ T cells. Throughout the study, virus replication correlated with the level of proliferating CD4+ T cells. CD4+ T cell depletion did not induce any changes in the fraction of Tregs or the level of SIV-specific CD8+ T cells. Our results suggest that the availability of activated CD4+ T cells, rather than immune control of SIV replication, is the main determinant of set-point viral load during natural SIV infection of SMs.

Cerebrospinal fluid neopterin decay characteristics after initiation of antiretroviral therapy.

PubMed

Yilmaz, Aylin; Yiannoutsos, Constantin T; Fuchs, Dietmar; Price, Richard W; Crozier, Kathryn; Hagberg, Lars; Spudich, Serena; Gisslén, Magnus

2013-05-10

Neopterin, a biomarker of macrophage activation, is elevated in the cerebrospinal fluid (CSF) of most HIV-infected individuals and decreases after initiation of antiretroviral therapy (ART). We studied decay characteristics of neopterin in CSF and blood after commencement of ART in HIV-infected subjects and estimated the set-point levels of CSF neopterin after ART-mediated viral suppression. CSF and blood neopterin were longitudinally measured in 102 neurologically asymptomatic HIV-infected subjects who were treatment-naïve or had been off ART for ≥ 6 months. We used a non-linear model to estimate neopterin decay in response to ART and a stable neopterin set-point attained after prolonged ART. Seven subjects with HIV-associated dementia (HAD) who initiated ART were studied for comparison. Non-HAD patients were followed for a median 84.7 months. Though CSF neopterin concentrations decreased rapidly after ART initiation, it was estimated that set-point levels would be below normal CSF neopterin levels (<5.8 nmol/L) in only 60/102 (59%) of these patients. Pre-ART CSF neopterin was the primary predictor of set-point (P <0.001). HAD subjects had higher baseline median CSF neopterin levels than non-HAD subjects (P <0.0001). Based on the non-HAD model, only 14% of HAD patients were predicted to reach normal levels. After virologically suppressive ART, abnormal CSF neopterin levels persisted in 41% of non-HAD and the majority of HAD patients. ART is not fully effective in ameliorating macrophage activation in CNS as well as blood, especially in subjects with higher pre-ART levels of immune activation.

Personality and serotonin transporter genotype interact with social context to affect immunity and viral set-point in simian immunodeficiency virus disease

PubMed Central

Capitanio, John P.; Abel, Kristina; Mendoza, Sally P.; Blozis, Shelley A.; McChesney, Michael B.; Cole, Steve W.; Mason, William A.

2008-01-01

From the beginning of the AIDS epidemic, stress has been a suspected contributor to the wide variation seen in disease progression, and some evidence supports this idea. Not all individuals respond to a stressor in the same way, however, and little is known about the biological mechanisms by which variations in individuals’ responses to their environment affect disease-relevant immunologic processes. Using the simian immunodeficiency virus/rhesus macaque model of AIDS, we explored how personality (sociability) and genotype (serotonin transporter promoter) independently interact with social context (stable or unstable social conditions) to influence behavioral expression, plasma cortisol concentrations, SIV-specific IgG, and expression of genes associated with Type I interferon early in infection. SIV viral RNA set-point was strongly and negatively correlated with survival as expected. Set-point was also associated with expression of interferon-stimulated genes, with CXCR3 expression, and with SIV-specific IgG titers. Poorer immune responses, in turn, were associated with display of sustained aggression and submission. Personality and genotype acted independently as well as in interaction with social condition to affect behavioral responses. Together, the data support an “interactionist” perspective (Eysenck, 1991) on disease. Given that an important goal of HIV treatment is to maintain viral set-point as low as possible, our data suggest that supplementing anti-retroviral therapy with behavioral or pharmacologic modulation of other aspects of an organism’s functioning might prolong survival, particularly among individuals living under conditions of threat or uncertainty. PMID:17719201

Continuous Firefly Algorithm for Optimal Tuning of Pid Controller in Avr System

NASA Astrophysics Data System (ADS)

Bendjeghaba, Omar

2014-01-01

This paper presents a tuning approach based on Continuous firefly algorithm (CFA) to obtain the proportional-integral- derivative (PID) controller parameters in Automatic Voltage Regulator system (AVR). In the tuning processes the CFA is iterated to reach the optimal or the near optimal of PID controller parameters when the main goal is to improve the AVR step response characteristics. Conducted simulations show the effectiveness and the efficiency of the proposed approach. Furthermore the proposed approach can improve the dynamic of the AVR system. Compared with particle swarm optimization (PSO), the new CFA tuning method has better control system performance in terms of time domain specifications and set-point tracking.

Effectiveness of Modal Decomposition for Tapping Atomic Force Microscopy Microcantilevers in Liquid Environment.

PubMed

Kim, Il Kwang; Lee, Soo Il

2016-05-01

The modal decomposition of tapping mode atomic force microscopy microcantilevers in liquid environments was studied experimentally. Microcantilevers with different lengths and stiffnesses and two sample surfaces with different elastic moduli were used in the experiment. The response modes of the microcantilevers were extracted as proper orthogonal modes through proper orthogonal decomposition. Smooth orthogonal decomposition was used to estimate the resonance frequency directly. The effects of the tapping setpoint and the elastic modulus of the sample under test were examined in terms of their multi-mode responses with proper orthogonal modes, proper orthogonal values, smooth orthogonal modes and smooth orthogonal values. Regardless of the stiffness of the microcantilever under test, the first mode was dominant in tapping mode atomic force microscopy under normal operating conditions. However, at lower tapping setpoints, the flexible microcantilever showed modal distortion and noise near the tip when tapping on a hard sample. The stiff microcantilever had a higher mode effect on a soft sample at lower tapping setpoints. Modal decomposition for tapping mode atomic force microscopy can thus be used to estimate the characteristics of samples in liquid environments.

Generalized compliant motion primitive

NASA Technical Reports Server (NTRS)

Backes, Paul G. (Inventor)

1994-01-01

This invention relates to a general primitive for controlling a telerobot with a set of input parameters. The primitive includes a trajectory generator; a teleoperation sensor; a joint limit generator; a force setpoint generator; a dither function generator, which produces telerobot motion inputs in a common coordinate frame for simultaneous combination in sensor summers. Virtual return spring motion input is provided by a restoration spring subsystem. The novel features of this invention include use of a single general motion primitive at a remote site to permit the shared and supervisory control of the robot manipulator to perform tasks via a remotely transferred input parameter set.

Robust control of flexible space vehicles with minimum structural excitation: On-off pulse control of flexible space vehicles

NASA Technical Reports Server (NTRS)

Wie, Bong; Liu, Qiang

1992-01-01

Both feedback and feedforward control approaches for uncertain dynamical systems (in particular, with uncertainty in structural mode frequency) are investigated. The control objective is to achieve a fast settling time (high performance) and robustness (insensitivity) to plant uncertainty. Preshaping of an ideal, time optimal control input using a tapped-delay filter is shown to provide a fast settling time with robust performance. A robust, non-minimum-phase feedback controller is synthesized with particular emphasis on its proper implementation for a non-zero set-point control problem. It is shown that a properly designed, feedback controller performs well, as compared with a time optimal open loop controller with special preshaping for performance robustness. Also included are two separate papers by the same authors on this subject.

Genetic analysis of the gravitropic set-point angle in lateral roots of Arabidopsis

NASA Technical Reports Server (NTRS)

Mullen, J. L.; Hangarter, R. P.; Kiss, J. Z. (Principal Investigator)

2003-01-01

Research on gravity responses in plants has mostly focused on primary roots and shoots, which typically orient to a vertical orientation. However, the distribution of lateral organs and their characteristically non-vertical growth orientation are critical for the determination of plant form. For example, in Arabidopsis, when lateral roots emerge from the primary root, they grow at a nearly horizontal orientation. As they elongate, the roots slowly curve until they eventually reach a vertical orientation. The regulation of this lateral root orientation is an important component affecting overall root system architecture. We found that this change in orientation is not simply due to the onset of gravitropic competence, as non-vertical lateral roots are capable of both positive and negative gravitropism. Thus, the horizontal growth of new lateral roots appears to be determined by what is called the gravitropic set-point angle (GSA). This developmental control of the GSA of lateral roots in Arabidopsis provides a useful system for investigating the components involved in regulating gravitropic responses. Using this system, we have identified several Arabidopsis mutants that have altered lateral root orientations but maintain normal primary root orientation. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Constrained tracking control for nonlinear systems.

PubMed

Khani, Fatemeh; Haeri, Mohammad

2017-09-01

This paper proposes a tracking control strategy for nonlinear systems without needing a prior knowledge of the reference trajectory. The proposed method consists of a set of local controllers with appropriate overlaps in their stability regions and an on-line switching strategy which implements these controllers and uses some augmented intermediate controllers to ensure steering the system states to the desired set points without needing to redesign the controller for each value of set point changes. The proposed approach provides smooth transient responses despite switching among the local controllers. It should be mentioned that the stability regions of the proposed controllers could be estimated off-line for a range of set-point changes. The efficiencies of the proposed algorithm are illustrated via two example simulations. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

An improved PID switching control strategy for type 1 diabetes.

PubMed

Marchetti, Gianni; Barolo, Massimiliano; Jovanovic, Lois; Zisser, Howard; Seborg, Dale E

2006-01-01

In order for an "artificial pancreas" to become a reality for ambulatory use, a practical closed-loop control strategy must be developed and critically evaluated. In this paper, an improved PID control strategy for blood glucose control is proposed and evaluated in silico using a physiologic model of Hovorka et al. The key features of the proposed control strategy are: (i) a switching strategy for initiating PID control after a meal and insulin bolus; (ii) a novel time-varying setpoint trajectory, (iii) noise and derivative filters to reduce sensitivity to sensor noise, and (iv) a systematic controller tuning strategy. Simulation results demonstrate that the proposed control strategy compares favorably to alternatives for realistic conditions that include meal challenges, incorrect carbohydrate meal estimates, changes in insulin sensitivity, and measurement noise.

Method and apparatus for adaptive force and position control of manipulators

NASA Technical Reports Server (NTRS)

Seraji, Homayoun (Inventor)

1989-01-01

The present invention discloses systematic methods and apparatus for the design of real time controllers. Real-time control employs adaptive force/position by use of feedforward and feedback controllers, with the feedforward controller being the inverse of the linearized model of robot dynamics and containing only proportional-double-derivative terms is disclosed. The feedback controller, of the proportional-integral-derivative type, ensures that manipulator joints follow reference trajectories and the feedback controller achieves robust tracking of step-plus-exponential trajectories, all in real time. The adaptive controller includes adaptive force and position control within a hybrid control architecture. The adaptive controller, for force control, achieves tracking of desired force setpoints, and the adaptive position controller accomplishes tracking of desired position trajectories. Circuits in the adaptive feedback and feedforward controllers are varied by adaptation laws.

Neural dynamic programming and its application to control systems

NASA Astrophysics Data System (ADS)

Seong, Chang-Yun

There are few general practical feedback control methods for nonlinear MIMO (multi-input-multi-output) systems, although such methods exist for their linear counterparts. Neural Dynamic Programming (NDP) is proposed as a practical design method of optimal feedback controllers for nonlinear MIMO systems. NDP is an offspring of both neural networks and optimal control theory. In optimal control theory, the optimal solution to any nonlinear MIMO control problem may be obtained from the Hamilton-Jacobi-Bellman equation (HJB) or the Euler-Lagrange equations (EL). The two sets of equations provide the same solution in different forms: EL leads to a sequence of optimal control vectors, called Feedforward Optimal Control (FOC); HJB yields a nonlinear optimal feedback controller, called Dynamic Programming (DP). DP produces an optimal solution that can reject disturbances and uncertainties as a result of feedback. Unfortunately, computation and storage requirements associated with DP solutions can be problematic, especially for high-order nonlinear systems. This dissertation presents an approximate technique for solving the DP problem based on neural network techniques that provides many of the performance benefits (e.g., optimality and feedback) of DP and benefits from the numerical properties of neural networks. We formulate neural networks to approximate optimal feedback solutions whose existence DP justifies. We show the conditions under which NDP closely approximates the optimal solution. Finally, we introduce the learning operator characterizing the learning process of the neural network in searching the optimal solution. The analysis of the learning operator provides not only a fundamental understanding of the learning process in neural networks but also useful guidelines for selecting the number of weights of the neural network. As a result, NDP finds---with a reasonable amount of computation and storage---the optimal feedback solutions to nonlinear MIMO control problems that would be very difficult to solve with DP. NDP was demonstrated on several applications such as the lateral autopilot logic for a Boeing 747, the minimum fuel control of a double-integrator plant with bounded control, the backward steering of a two-trailer truck, and the set-point control of a two-link robot arm.

The Design of a Transparent Vertical Multizone Furnace: Application to Thermal Field Tuning and Crystal Growth

NASA Technical Reports Server (NTRS)

Duvual, Walter M. B.; Batur, Celal; Bennett, Robert J.

1998-01-01

We present an innovative design of a vertical transparent multizone furnace which can operate in the temperature range of 25 C to 750 C and deliver thermal gradients of 2 C/cm to 45 C/cm for the commercial applications to crystal growth. The operation of the eight zone furnace is based on a self-tuning temperature control system with a DC power supply for optimal thermal stability. We show that the desired thermal profile over the entire length of the furnace consists of a functional combination of the fundamental thermal profiles for each individual zone obtained by setting the set-point temperature for that zone. The self-tuning system accounts for the zone to zone thermal interactions. The control system operates such that the thermal profile is maintained under thermal load, thus boundary conditions on crystal growth ampoules can be predetermined prior to crystal growth. Temperature profiles for the growth of crystals via directional solidification, vapor transport techniques, and multiple gradient applications are shown to be easily implemented. The unique feature of its transparency and ease of programming thermal profiles make the furnace useful in scientific and commercial applications for determining the optimized process parameters for crystal growth.

Systems and methods for controlling energy use in a building management system using energy budgets

DOEpatents

Wenzel, Michael J.

2012-06-17

Systems and methods for limiting power consumption by a heating, ventilation, and air conditioning (HVAC) subsystem of a building are shown and described. A mathematical linear operator is found that transforms the unused or deferred cooling power usage of the HVAC system based on pre-determined temperature settings to a target cooling power usage. The mathematical operator is applied to the temperature settings to create a temperature setpoint trajectory expected to provide the target cooling power usage.

Adaptive hybrid control of manipulators

NASA Technical Reports Server (NTRS)

Seraji, H.

1987-01-01

Simple methods for the design of adaptive force and position controllers for robot manipulators within the hybrid control architecuture is presented. The force controller is composed of an adaptive PID feedback controller, an auxiliary signal and a force feedforward term, and it achieves tracking of desired force setpoints in the constraint directions. The position controller consists of adaptive feedback and feedforward controllers and an auxiliary signal, and it accomplishes tracking of desired position trajectories in the free directions. The controllers are capable of compensating for dynamic cross-couplings that exist between the position and force control loops in the hybrid control architecture. The adaptive controllers do not require knowledge of the complex dynamic model or parameter values of the manipulator or the environment. The proposed control schemes are computationally fast and suitable for implementation in on-line control with high sampling rates.

Bacterial adhesion force quantification by fluidic force microscopy

NASA Astrophysics Data System (ADS)

Potthoff, Eva; Ossola, Dario; Zambelli, Tomaso; Vorholt, Julia A.

2015-02-01

Quantification of detachment forces between bacteria and substrates facilitates the understanding of the bacterial adhesion process that affects cell physiology and survival. Here, we present a method that allows for serial, single bacterial cell force spectroscopy by combining the force control of atomic force microscopy with microfluidics. Reversible bacterial cell immobilization under physiological conditions on the pyramidal tip of a microchanneled cantilever is achieved by underpressure. Using the fluidic force microscopy technology (FluidFM), we achieve immobilization forces greater than those of state-of-the-art cell-cantilever binding as demonstrated by the detachment of Escherichia coli from polydopamine with recorded forces between 4 and 8 nN for many cells. The contact time and setpoint dependence of the adhesion forces of E. coli and Streptococcus pyogenes, as well as the sequential detachment of bacteria out of a chain, are shown, revealing distinct force patterns in the detachment curves. This study demonstrates the potential of the FluidFM technology for quantitative bacterial adhesion measurements of cell-substrate and cell-cell interactions that are relevant in biofilms and infection biology.Quantification of detachment forces between bacteria and substrates facilitates the understanding of the bacterial adhesion process that affects cell physiology and survival. Here, we present a method that allows for serial, single bacterial cell force spectroscopy by combining the force control of atomic force microscopy with microfluidics. Reversible bacterial cell immobilization under physiological conditions on the pyramidal tip of a microchanneled cantilever is achieved by underpressure. Using the fluidic force microscopy technology (FluidFM), we achieve immobilization forces greater than those of state-of-the-art cell-cantilever binding as demonstrated by the detachment of Escherichia coli from polydopamine with recorded forces between 4 and 8 nN for many cells. The contact time and setpoint dependence of the adhesion forces of E. coli and Streptococcus pyogenes, as well as the sequential detachment of bacteria out of a chain, are shown, revealing distinct force patterns in the detachment curves. This study demonstrates the potential of the FluidFM technology for quantitative bacterial adhesion measurements of cell-substrate and cell-cell interactions that are relevant in biofilms and infection biology. Electronic supplementary information (ESI) available: Video S1. Detachment of a S. pyogenes cell chain from glass substrate. The cantilever is approached on the outermost adherent cell of a chain and four bacteria were then sequentially detached. The sequential cell detachment suddenly stopped after four bacteria. This possibly occurred because bacteria-glass interactions became too strong or the maximal probe retraction was reached. The cells spontaneously detached from the cantilever flipping back on the surface. Fig. S1. (A) Adhesion force-distance and (B) adhesion force-detaching work correlation of E.coli on PLL for setpoints of 1 and 10 nN. Circle: 1 nN setpoint, square: 10 nN. See DOI: 10.1039/c4nr06495j

Control of Adventitious Root Architecture in Rice by Darkness, Light, and Gravity1[OPEN

PubMed Central

2018-01-01

Rice (Oryza sativa) is a semiaquatic plant that is well adapted to partial flooding. Rice stems develop adventitious root (AR) primordia at each node that slowly mature but emerge only when the plant gets flooded, leading to the formation of a whole new secondary root system upon flooding. AR growth is induced by ethylene that accumulates in submerged plant tissues due to its lowered diffusion rate in water. Here, we report that the architecture of the secondary root system in flooded rice plants is controlled not only by altered gas diffusion but also by gravity and light. While ethylene promotes the emergence and growth of ARs, gravity and light determine their gravitropic setpoint angle (i.e. the deviation of growth direction relative to vertical). ARs grow upward at about 120° in the dark and downward at 54° in the light. The upward growth direction is conserved in indica and japonica rice varieties, suggestive of a conserved trait in rice. Experiments with a klinostat and with inverted stem orientation revealed that gravity promotes upward growth by about 10°. Red, far-red, and blue light lead to negative phototropism in a dose-dependent manner, with blue light being most effective, indicating that phytochrome and blue light signaling control AR system architecture. The cpt1 (coleoptile phototropism1) mutant, which lacks one of the phototropin-interacting CPT proteins, shows reduced sensitivity to blue light. Hence, the gravitropic setpoint angle of rice ARs is controlled by genetic and environmental factors that likely balance the need for oxygen supply (upward growth) with avoidance of root desiccation (downward growth). PMID:29242375

Control of Adventitious Root Architecture in Rice by Darkness, Light, and Gravity.

PubMed

Lin, Chen; Sauter, Margret

2018-02-01

Rice ( Oryza sativa ) is a semiaquatic plant that is well adapted to partial flooding. Rice stems develop adventitious root (AR) primordia at each node that slowly mature but emerge only when the plant gets flooded, leading to the formation of a whole new secondary root system upon flooding. AR growth is induced by ethylene that accumulates in submerged plant tissues due to its lowered diffusion rate in water. Here, we report that the architecture of the secondary root system in flooded rice plants is controlled not only by altered gas diffusion but also by gravity and light. While ethylene promotes the emergence and growth of ARs, gravity and light determine their gravitropic setpoint angle (i.e. the deviation of growth direction relative to vertical). ARs grow upward at about 120° in the dark and downward at 54° in the light. The upward growth direction is conserved in indica and japonica rice varieties, suggestive of a conserved trait in rice. Experiments with a klinostat and with inverted stem orientation revealed that gravity promotes upward growth by about 10°. Red, far-red, and blue light lead to negative phototropism in a dose-dependent manner, with blue light being most effective, indicating that phytochrome and blue light signaling control AR system architecture. The cpt1 ( coleoptile phototropism1 ) mutant, which lacks one of the phototropin-interacting CPT proteins, shows reduced sensitivity to blue light. Hence, the gravitropic setpoint angle of rice ARs is controlled by genetic and environmental factors that likely balance the need for oxygen supply (upward growth) with avoidance of root desiccation (downward growth). © 2018 American Society of Plant Biologists. All Rights Reserved.

Dissecting HIV Virulence: Heritability of Setpoint Viral Load, CD4+ T-Cell Decline, and Per-Parasite Pathogenicity.

PubMed

Bertels, Frederic; Marzel, Alex; Leventhal, Gabriel; Mitov, Venelin; Fellay, Jacques; Günthard, Huldrych F; Böni, Jürg; Yerly, Sabine; Klimkait, Thomas; Aubert, Vincent; Battegay, Manuel; Rauch, Andri; Cavassini, Matthias; Calmy, Alexandra; Bernasconi, Enos; Schmid, Patrick; Scherrer, Alexandra U; Müller, Viktor; Bonhoeffer, Sebastian; Kouyos, Roger; Regoes, Roland R

2018-01-01

Pathogen strains may differ in virulence because they attain different loads in their hosts, or because they induce different disease-causing mechanisms independent of their load. In evolutionary ecology, the latter is referred to as "per-parasite pathogenicity". Using viral load and CD4+ T-cell measures from 2014 HIV-1 subtype B-infected individuals enrolled in the Swiss HIV Cohort Study, we investigated if virulence-measured as the rate of decline of CD4+ T cells-and per-parasite pathogenicity are heritable from donor to recipient. We estimated heritability by donor-recipient regressions applied to 196 previously identified transmission pairs, and by phylogenetic mixed models applied to a phylogenetic tree inferred from HIV pol sequences. Regressing the CD4+ T-cell declines and per-parasite pathogenicities of the transmission pairs did not yield heritability estimates significantly different from zero. With the phylogenetic mixed model, however, our best estimate for the heritability of the CD4+ T-cell decline is 17% (5-30%), and that of the per-parasite pathogenicity is 17% (4-29%). Further, we confirm that the set-point viral load is heritable, and estimate a heritability of 29% (12-46%). Interestingly, the pattern of evolution of all these traits differs significantly from neutrality, and is most consistent with stabilizing selection for the set-point viral load, and with directional selection for the CD4+ T-cell decline and the per-parasite pathogenicity. Our analysis shows that the viral genotype affects virulence mainly by modulating the per-parasite pathogenicity, while the indirect effect via the set-point viral load is minor. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Dissecting HIV Virulence: Heritability of Setpoint Viral Load, CD4+ T-Cell Decline, and Per-Parasite Pathogenicity

PubMed Central

Bertels, Frederic; Marzel, Alex; Leventhal, Gabriel; Mitov, Venelin; Fellay, Jacques; Günthard, Huldrych F; Böni, Jürg; Yerly, Sabine; Klimkait, Thomas; Aubert, Vincent; Battegay, Manuel; Rauch, Andri; Cavassini, Matthias; Calmy, Alexandra; Bernasconi, Enos; Schmid, Patrick; Scherrer, Alexandra U; Müller, Viktor; Bonhoeffer, Sebastian; Kouyos, Roger; Regoes, Roland R

2018-01-01

Abstract Pathogen strains may differ in virulence because they attain different loads in their hosts, or because they induce different disease-causing mechanisms independent of their load. In evolutionary ecology, the latter is referred to as “per-parasite pathogenicity”. Using viral load and CD4+ T-cell measures from 2014 HIV-1 subtype B-infected individuals enrolled in the Swiss HIV Cohort Study, we investigated if virulence—measured as the rate of decline of CD4+ T cells—and per-parasite pathogenicity are heritable from donor to recipient. We estimated heritability by donor–recipient regressions applied to 196 previously identified transmission pairs, and by phylogenetic mixed models applied to a phylogenetic tree inferred from HIV pol sequences. Regressing the CD4+ T-cell declines and per-parasite pathogenicities of the transmission pairs did not yield heritability estimates significantly different from zero. With the phylogenetic mixed model, however, our best estimate for the heritability of the CD4+ T-cell decline is 17% (5–30%), and that of the per-parasite pathogenicity is 17% (4–29%). Further, we confirm that the set-point viral load is heritable, and estimate a heritability of 29% (12–46%). Interestingly, the pattern of evolution of all these traits differs significantly from neutrality, and is most consistent with stabilizing selection for the set-point viral load, and with directional selection for the CD4+ T-cell decline and the per-parasite pathogenicity. Our analysis shows that the viral genotype affects virulence mainly by modulating the per-parasite pathogenicity, while the indirect effect via the set-point viral load is minor. PMID:29029206

Cerebrospinal fluid neopterin decay characteristics after initiation of antiretroviral therapy

PubMed Central

2013-01-01

Background Neopterin, a biomarker of macrophage activation, is elevated in the cerebrospinal fluid (CSF) of most HIV-infected individuals and decreases after initiation of antiretroviral therapy (ART). We studied decay characteristics of neopterin in CSF and blood after commencement of ART in HIV-infected subjects and estimated the set-point levels of CSF neopterin after ART-mediated viral suppression. Methods CSF and blood neopterin were longitudinally measured in 102 neurologically asymptomatic HIV-infected subjects who were treatment-naïve or had been off ART for ≥ 6 months. We used a non-linear model to estimate neopterin decay in response to ART and a stable neopterin set-point attained after prolonged ART. Seven subjects with HIV-associated dementia (HAD) who initiated ART were studied for comparison. Results Non-HAD patients were followed for a median 84.7 months. Though CSF neopterin concentrations decreased rapidly after ART initiation, it was estimated that set-point levels would be below normal CSF neopterin levels (<5.8 nmol/L) in only 60/102 (59%) of these patients. Pre-ART CSF neopterin was the primary predictor of set-point (P <0.001). HAD subjects had higher baseline median CSF neopterin levels than non-HAD subjects (P <0.0001). Based on the non-HAD model, only 14% of HAD patients were predicted to reach normal levels. Conclusions After virologically suppressive ART, abnormal CSF neopterin levels persisted in 41% of non-HAD and the majority of HAD patients. ART is not fully effective in ameliorating macrophage activation in CNS as well as blood, especially in subjects with higher pre-ART levels of immune activation. PMID:23664008

Field Test of Boiler Primary Loop Temperature Controller

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glanville, P.; Rowley, P.; Schroeder, D.

Beyond these initial system efficiency upgrades are an emerging class of Advanced Load Monitoring (ALM) aftermarket controllers that dynamically respond to the boiler load, with claims of 10% to 30% of fuel savings over a heating season. For hydronic boilers specifically, these devices perform load monitoring, with continuous measurement of supply and, in some cases, return water temperatures. Energy savings from these ALM controllers are derived from dynamic management of the boiler differential, where a microprocessor with memory of past boiler cycles prevents the boiler from firing for a period of time, to limit cycling losses and inefficient operation duringmore » perceived low load conditions. These differ from OTR controllers, which vary boiler setpoint temperatures with ambient conditions while maintaining a fixed differential.« less

Internal combustion engine control for series hybrid electric vehicles by parallel and distributed genetic programming/multiobjective genetic algorithms

NASA Astrophysics Data System (ADS)

Gladwin, D.; Stewart, P.; Stewart, J.

2011-02-01

This article addresses the problem of maintaining a stable rectified DC output from the three-phase AC generator in a series-hybrid vehicle powertrain. The series-hybrid prime power source generally comprises an internal combustion (IC) engine driving a three-phase permanent magnet generator whose output is rectified to DC. A recent development has been to control the engine/generator combination by an electronically actuated throttle. This system can be represented as a nonlinear system with significant time delay. Previously, voltage control of the generator output has been achieved by model predictive methods such as the Smith Predictor. These methods rely on the incorporation of an accurate system model and time delay into the control algorithm, with a consequent increase in computational complexity in the real-time controller, and as a necessity relies to some extent on the accuracy of the models. Two complementary performance objectives exist for the control system. Firstly, to maintain the IC engine at its optimal operating point, and secondly, to supply a stable DC supply to the traction drive inverters. Achievement of these goals minimises the transient energy storage requirements at the DC link, with a consequent reduction in both weight and cost. These objectives imply constant velocity operation of the IC engine under external load disturbances and changes in both operating conditions and vehicle speed set-points. In order to achieve these objectives, and reduce the complexity of implementation, in this article a controller is designed by the use of Genetic Programming methods in the Simulink modelling environment, with the aim of obtaining a relatively simple controller for the time-delay system which does not rely on the implementation of real time system models or time delay approximations in the controller. A methodology is presented to utilise the miriad of existing control blocks in the Simulink libraries to automatically evolve optimal control structures.

An optimization-based approach for facility energy management with uncertainties, and, Power portfolio optimization in deregulated electricity markets with risk management

NASA Astrophysics Data System (ADS)

Xu, Jun

Topic 1. An Optimization-Based Approach for Facility Energy Management with Uncertainties. Effective energy management for facilities is becoming increasingly important in view of the rising energy costs, the government mandate on the reduction of energy consumption, and the human comfort requirements. This part of dissertation presents a daily energy management formulation and the corresponding solution methodology for HVAC systems. The problem is to minimize the energy and demand costs through the control of HVAC units while satisfying human comfort, system dynamics, load limit constraints, and other requirements. The problem is difficult in view of the fact that the system is nonlinear, time-varying, building-dependent, and uncertain; and that the direct control of a large number of HVAC components is difficult. In this work, HVAC setpoints are the control variables developed on top of a Direct Digital Control (DDC) system. A method that combines Lagrangian relaxation, neural networks, stochastic dynamic programming, and heuristics is developed to predict the system dynamics and uncontrollable load, and to optimize the setpoints. Numerical testing and prototype implementation results show that our method can effectively reduce total costs, manage uncertainties, and shed the load, is computationally efficient. Furthermore, it is significantly better than existing methods. Topic 2. Power Portfolio Optimization in Deregulated Electricity Markets with Risk Management. In a deregulated electric power system, multiple markets of different time scales exist with various power supply instruments. A load serving entity (LSE) has multiple choices from these instruments to meet its load obligations. In view of the large amount of power involved, the complex market structure, risks in such volatile markets, stringent constraints to be satisfied, and the long time horizon, a power portfolio optimization problem is of critical importance but difficulty for an LSE to serve the load, maximize its profit, and manage risks. In this topic, a mid-term power portfolio optimization problem with risk management is presented. Key instruments are considered, risk terms based on semi-variances of spot market transactions are introduced, and penalties on load obligation violations are added to the objective function to improve algorithm convergence and constraint satisfaction. To overcome the inseparability of the resulting problem, a surrogate optimization framework is developed enabling a decomposition and coordination approach. Numerical testing results show that our method effectively provides decisions for various instruments to maximize profit, manage risks, and is computationally efficient.

Availability of activated CD4+ T cells dictates the level of viremia in naturally SIV-infected sooty mangabeys

PubMed Central

Klatt, Nichole R.; Villinger, Francois; Bostik, Pavel; Gordon, Shari N.; Pereira, Lara; Engram, Jessica C.; Mayne, Ann; Dunham, Richard M.; Lawson, Benton; Ratcliffe, Sarah J.; Sodora, Donald L.; Else, James; Reimann, Keith; Staprans, Silvija I.; Haase, Ashley T.; Estes, Jacob D.; Silvestri, Guido; Ansari, Aftab A.

2008-01-01

Naturally SIV-infected sooty mangabeys (SMs) remain asymptomatic despite high virus replication. Elucidating the mechanisms underlying AIDS resistance of SIV-infected SMs may provide crucial information to better understand AIDS pathogenesis. In this study, we assessed the determinants of set-point viremia in naturally SIV-infected SMs, i.e., immune control of SIV replication versus target cell limitation. We depleted CD4+ T cells in 6 naturally SIV-infected SMs by treating with humanized anti-CD4 mAb (Cdr-OKT4A-huIgG1). CD4+ T cells were depleted almost completely in blood and BM and at variable levels in mucosal tissues and LNs. No marked depletion of CD14+ monocytes was observed. Importantly, CD4+ T cell depletion was associated with a rapid, significant decline in viral load, which returned to baseline level at day 30–45, coincident with an increased fraction of proliferating and activated CD4+ T cells. Throughout the study, virus replication correlated with the level of proliferating CD4+ T cells. CD4+ T cell depletion did not induce any changes in the fraction of Tregs or the level of SIV-specific CD8+ T cells. Our results suggest that the availability of activated CD4+ T cells, rather than immune control of SIV replication, is the main determinant of set-point viral load during natural SIV infection of SMs. PMID:18497876

Pulse-modulated dual-gas control subsystem for space cabin atmosphere

NASA Technical Reports Server (NTRS)

Jackson, J. K.

1974-01-01

An atmosphere control subsystem (ACS) was developed for use in a closed manned cabin, such as the Space Shuttle Orbiter. This subsystem uses the Perkin Elmer mass spectrometer for continuous measurement of major atmospheric constituents (H2, H2O, N2, O2, and CO2). The O2 and N2 analog signals are used as inputs to the controller, which produces a pulse-frequency-modulated output to operate the N2 gas admission solenoid valve and an on-off signal to operate the O2 valve. The proportional controller characteristic results in improved control accuracy as compared with previously used on-off controllers having significant dead-band. A 60-day evaluation test was performed on the ACS during which operation was measured at various values of control setpoint and simulated cabin leakage.

Actively Controlled Shaft Seals for Aerospace Applications

NASA Technical Reports Server (NTRS)

Salant, Richard F.; Wolff, Paul

1995-01-01

This study experimentally investigates an actively controlled mechanical seal for aerospace applications. The seal of interest is a gas seal, which is considerably more compact than previous actively controlled mechanical seals that were developed for industrial use. In a mechanical seal, the radial convergence of the seal interface has a primary effect on the film thickness. Active control of the film thickness is established by controlling the radial convergence of the seal interface with a piezoelectric actuator. An actively controlled mechanical seal was initially designed and evaluated using a mathematical model. Based on these results, a seal was fabricated and tested under laboratory conditions. The seal was tested with both helium and air, at rotational speeds up to 3770 rad/sec, and at sealed pressures as high as 1.48 x 10(exp 6) Pa. The seal was operated with both manual control and with a closed-loop control system that used either the leakage rate or face temperature as the feedback. The output of the controller was the voltage applied to the piezoelectric actuator. The seal operated successfully for both short term tests (less than one hour) and for longer term tests (four hours) with a closed-loop control system. The leakage rates were typically 5-15 slm (standard liters per minute), and the face temperatures were generally maintained below 100C. When leakage rate was used as the feedback signal, the setpoint leakage rate was typically maintained within 1 slm. However, larger deviations occurred during sudden changes in sealed pressure. When face temperature was used as the feedback signal, the setpoint face temperature was generally maintained within 3 C, with larger deviations occurring when the sealed pressure changes suddenly. the experimental results were compared to the predictions from the mathematical model. The model was successful in predicting the trends in leakage rate that occurred as the balance ratio and sealed pressure changed, although the leakage rates were not quantitatively predicted with a high degree of accuracy. This model could be useful in providing valuable design information for future actively controlled mechanical seals.

Decentralized Optimal Dispatch of Photovoltaic Inverters in Residential Distribution Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Dhople, Sairaj V.; Johnson, Brian B.

Summary form only given. Decentralized methods for computing optimal real and reactive power setpoints for residential photovoltaic (PV) inverters are developed in this paper. It is known that conventional PV inverter controllers, which are designed to extract maximum power at unity power factor, cannot address secondary performance objectives such as voltage regulation and network loss minimization. Optimal power flow techniques can be utilized to select which inverters will provide ancillary services, and to compute their optimal real and reactive power setpoints according to well-defined performance criteria and economic objectives. Leveraging advances in sparsity-promoting regularization techniques and semidefinite relaxation, this papermore » shows how such problems can be solved with reduced computational burden and optimality guarantees. To enable large-scale implementation, a novel algorithmic framework is introduced - based on the so-called alternating direction method of multipliers - by which optimal power flow-type problems in this setting can be systematically decomposed into sub-problems that can be solved in a decentralized fashion by the utility and customer-owned PV systems with limited exchanges of information. Since the computational burden is shared among multiple devices and the requirement of all-to-all communication can be circumvented, the proposed optimization approach scales favorably to large distribution networks.« less

Design and Testing of a Variable Pressure Regulator for the Constellation Space Suit

NASA Technical Reports Server (NTRS)

Gill, Larry; Campbell, Colin

2008-01-01

The next generation space suit requires additional capabilities for controlling and adjusting internal pressure than previous design suits. Next generation suit pressures will range from slight pressure, for astronaut prebreath comfort, to hyperbaric pressure levels for emergency medical treatment. Carleton was awarded a contract in 2008 to design and build a proof of concept bench top demonstrator regulator having five setpoints which are selectable using input electronic signaling. Although the basic regulator architecture is very similar to the existing SOP regulator used in the current EMU, the major difference is the electrical selectivity of multiple setpoints rather than the mechanical On/Off feature found on the SOP regulator. The concept regulator employs a linear actuator stepper motor combination to provide variable compression to a custom design main regulator spring. This concept allows for a continuously adjustable outlet pressures from 8.2 psid (maximum) down to "firm" zero thus effectively allowing it to serve as a shutoff valve. This paper details the regulator design and presents test results on regulation band width, command set point accuracy; slue rate and regulation stability, particularly when the set point is being slued. Projections for a flight configuration version are also offered for performance, architectural layout and weight.

Balance between transmitted HLA preadapted and nonassociated polymorphisms is a major determinant of HIV-1 disease progression.

PubMed

Mónaco, Daniela C; Dilernia, Dario A; Fiore-Gartland, Andrew; Yu, Tianwei; Prince, Jessica L; Dennis, Kristine K; Qin, Kai; Schaefer, Malinda; Claiborne, Daniel T; Kilembe, William; Tang, Jianming; Price, Matt A; Farmer, Paul; Gilmour, Jill; Bansal, Anju; Allen, Susan; Goepfert, Paul; Hunter, Eric

2016-09-19

HIV-1 adapts to a new host through mutations that facilitate immune escape. Here, we evaluate the impact on viral control and disease progression of transmitted polymorphisms that were either preadapted to or nonassociated with the new host's HLA. In a cohort of 169 Zambian heterosexual transmission pairs, we found that almost one-third of possible HLA-linked target sites in the transmitted virus Gag protein are already adapted, and that this transmitted preadaptation significantly reduced early immune recognition of epitopes. Transmitted preadapted and nonassociated polymorphisms showed opposing effects on set-point VL and the balance between the two was significantly associated with higher set-point VLs in a multivariable model including other risk factors. Transmitted preadaptation was also significantly associated with faster CD4 decline (<350 cells/µl) and this association was stronger after accounting for nonassociated polymorphisms, which were linked with slower CD4 decline. Overall, the relative ratio of the two classes of polymorphisms was found to be the major determinant of CD4 decline in a multivariable model including other risk factors. This study reveals that, even before an immune response is mounted in the new host, the balance of these opposing factors can significantly influence the outcome of HIV-1 infection. © 2016 Mónaco et al.

Computer software configuration description, 241-AY and 241-AZ tank farm MICON automation system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winkelman, W.D.

This document describes the configuration process, choices and conventions used during the configuration activities, and issues involved in making changes to the configuration. Includes the master listings of the Tag definitions, which should be revised to authorize any changes. Revision 2 incorporates minor changes to ensure the document setpoints accurately reflect limits (including exhaust stack flow of 800 scfm) established in OSD-T-151-00019. The MICON DCS software controls and monitors the instrumentation and equipment associated with plant systems and processes.

Integration of Energy/Sustainable Practices into Standard Army MILCON Designs: Energy and Sustainability Study

DTIC Science & Technology

2010-11-30

approved climate zones) ► Dual flush toilets ► 1.5 GPM flow shower heads ► 0.5 GPM flow faucets ► Rainwater harvesting ► Permeable asphalt, permeable...for system with indirect evaporative pre-cooling Sustainability Measures ► Dual flush toilets ► 1.5 GPM flow shower heads, 0.5 GPM flow faucets...daylighting controls with 500 lux setpoint ► Dual flush toilets ►Waterless urinals ► 0.5 GPM flow faucets ► Rainwater harvesting ► Enhanced Commissioning

Dynamic optimization of CELSS crop photosynthetic rate by computer-assisted feedback control

NASA Astrophysics Data System (ADS)

Chun, C.; Mitchell, C. A.

1997-01-01

A procedure for dynamic optimization of net photosynthetic rate (Pn) for crop production in Controlled Ecological Life-Support Systems (CELSS) was developed using leaf lettuce as a model crop. Canopy Pn was measured in real time and fed back for environmental control. Setpoints of photosynthetic photon flux (PPF) and CO_2 concentration for each hour of the crop-growth cycle were decided by computer to reach a targeted Pn each day. Decision making was based on empirical mathematical models combined with rule sets developed from recent experimental data. Comparisons showed that dynamic control resulted in better yield per unit energy input to the growth system than did static control. With comparable productivity parameters and potential for significant energy savings, dynamic control strategies will contribute greatly to the sustainability of space-deployed CELSS.

Stability, resolution, and ultra-low wear amplitude modulation atomic force microscopy of DNA: Small amplitude small set-point imaging

NASA Astrophysics Data System (ADS)

Santos, Sergio; Barcons, Victor; Christenson, Hugo K.; Billingsley, Daniel J.; Bonass, William A.; Font, Josep; Thomson, Neil H.

2013-08-01

A way to operate fundamental mode amplitude modulation atomic force microscopy is introduced which optimizes stability and resolution for a given tip size and shows negligible tip wear over extended time periods (˜24 h). In small amplitude small set-point (SASS) imaging, the cantilever oscillates with sub-nanometer amplitudes in the proximity of the sample, without the requirement of using large drive forces, as the dynamics smoothly lead the tip to the surface through the water layer. SASS is demonstrated on single molecules of double-stranded DNA in ambient conditions where sharp silicon tips (R ˜ 2-5 nm) can resolve the right-handed double helix.

Alternatives for jet engine control

NASA Technical Reports Server (NTRS)

Sain, M. K.

1979-01-01

The research is classified in two categories: (1) the use of modern multivariable frequency domain methods for control of engine models in the neighborhood of a set-point, and (2) the use of nonlinear modelling and optimization techniques for control of engine models over a more extensive part of the flight envelope. Progress in the first category included the extension of CARDIAD (Complex Acceptability Region for Diagonal Dominance) methods developed with the help of the grant to the case of engine models with four inputs and four outputs. A suitable bounding procedure for the dominance function was determined. Progress in the second category had its principal focus on automatic nonlinear model generation. Simulations of models produced satisfactory results where compared with the NASA DYNGEN digital engine deck.

Performance and power regulation characteristics of two aileron-controlled rotors and a pitchable tip-controlled rotor on the Mod-O turbine

NASA Technical Reports Server (NTRS)

Corrigan, Robert D.; Ensworth, Clinton B. F., III; Miller, Dean R.

1987-01-01

Tests were conducted on the DOE/NASA mod-0 horizontal axis wind turbine to compare and evaluate the performance and the power regulation characteristics of two aileron-controlled rotors and a pitchable tip-controlled rotor. The two aileron-controlled rotor configurations used 20 and 38 percent chord ailerons, while the tip-controlled rotor had a pitchable blade tip. The ability of the control surfaces to regulate power was determined by measuring the change in power caused by an incremental change in the deflection angle of the control surface. The data shows that the change in power per degree of deflection angle for the tip-controlled rotor was four times the corresponding value for the 2- percent chord ailerons. The root mean square power deviation about a power setpoint was highest for the 20 percent chord aileron, and lowest for the 38 percent chord aileron.

Fatigue minimising power reference control of a de-rated wind farm

NASA Astrophysics Data System (ADS)

Jensen, T. N.; Knudsen, T.; Bak, T.

2016-09-01

Modern wind farms (cluster of wind turbines) can be required to control the total power output to meet a set-point, and would then profit by minimising the structural loads and thereby the cost of energy. In this paper, we propose a new control strategy for a derated wind farm with the objective of maintaining a desired reference power production for the wind farm, while minimising the sum of fatigues on the wind turbines in steady-state. The controller outputs a vector of power references for the individual turbines. It exploits the positive correlation between fatigue and added turbulence to minimise fatigue indirectly by minimising the added turbulence. Simulated results for a wind farm with three turbines demonstrate the efficacy of the proposed solution by assessing the damage equivalent loads.

Nutrigenomics of Body Weight Regulation: A Rationale for Careful Dissection of Individual Contributors

PubMed Central

Keijer, Jaap; Hoevenaars, Femke P. M.; Nieuwenhuizen, Arie; van Schothorst, Evert M.

2014-01-01

Body weight stability may imply active regulation towards a certain physiological condition, a body weight setpoint. This interpretation is ill at odds with the world-wide increase in overweight and obesity. Until now, a body weight setpoint has remained elusive and the setpoint theory did not provide practical clues for body weight reduction interventions. For this an alternative theoretical model is necessary, which is available as the settling point model. The settling point model postulates that there is little active regulation towards a predefined body weight, but that body weight settles based on the resultant of a number of contributors, represented by the individual’s genetic predisposition, in interaction with environmental and socioeconomic factors, such as diet and lifestyle. This review refines the settling point model and argues that by taking body weight regulation from a settling point perspective, the road will be opened to careful dissection of the various contributors to establishment of body weight and its regulation. This is both necessary and useful. Nutrigenomic technologies may help to delineate contributors to body weight settling. Understanding how and to which extent the different contributors influence body weight will allow the design of weight loss and weight maintenance interventions, which hopefully are more successful than those that are currently available. PMID:25338273

Nutrigenomics of body weight regulation: a rationale for careful dissection of individual contributors.

PubMed

Keijer, Jaap; Hoevenaars, Femke P M; Nieuwenhuizen, Arie; van Schothorst, Evert M

2014-10-21

Body weight stability may imply active regulation towards a certain physiological condition, a body weight setpoint. This interpretation is ill at odds with the world-wide increase in overweight and obesity. Until now, a body weight setpoint has remained elusive and the setpoint theory did not provide practical clues for body weight reduction interventions. For this an alternative theoretical model is necessary, which is available as the settling point model. The settling point model postulates that there is little active regulation towards a predefined body weight, but that body weight settles based on the resultant of a number of contributors, represented by the individual's genetic predisposition, in interaction with environmental and socioeconomic factors, such as diet and lifestyle. This review refines the settling point model and argues that by taking body weight regulation from a settling point perspective, the road will be opened to careful dissection of the various contributors to establishment of body weight and its regulation. This is both necessary and useful. Nutrigenomic technologies may help to delineate contributors to body weight settling. Understanding how and to which extent the different contributors influence body weight will allow the design of weight loss and weight maintenance interventions, which hopefully are more successful than those that are currently available.

Nonlinear Adaptive PID Control for Greenhouse Environment Based on RBF Network

PubMed Central

Zeng, Songwei; Hu, Haigen; Xu, Lihong; Li, Guanghui

2012-01-01

This paper presents a hybrid control strategy, combining Radial Basis Function (RBF) network with conventional proportional, integral, and derivative (PID) controllers, for the greenhouse climate control. A model of nonlinear conservation laws of enthalpy and matter between numerous system variables affecting the greenhouse climate is formulated. RBF network is used to tune and identify all PID gain parameters online and adaptively. The presented Neuro-PID control scheme is validated through simulations of set-point tracking and disturbance rejection. We compare the proposed adaptive online tuning method with the offline tuning scheme that employs Genetic Algorithm (GA) to search the optimal gain parameters. The results show that the proposed strategy has good adaptability, strong robustness and real-time performance while achieving satisfactory control performance for the complex and nonlinear greenhouse climate control system, and it may provide a valuable reference to formulate environmental control strategies for actual application in greenhouse production. PMID:22778587

Evidence from catch-up growth and hoarding behavior of rats that exposure to hypobaric air lowers the body-mass set point.

PubMed

Bozzini, Carlos E; Lezón, Christian E; Norese, María F; Conti, María I; Martínez, María P; Olivera, María I; Alippi, Rosa M

2005-01-01

The depression of body growth rate and the reduction of body mass for chronological age and gender in growing experimental animals exposed to hypobaric air (simulated high altitude = SHA) have been associated with hypophagia because of reduced appetite. Catch-up growth during protein recovery after a short period of protein restriction only occurs if food intake becomes super-normal, which should not be possible under hypoxic conditions if the set-point for appetite is adjusted by the level of SHA. The present investigation was designed to test the hypothesis that growth retardation during exposure to SHA is due to an alteration of the neural mechanism for setting body mass size rather than a primary alteration of the central set-point for appetite. One group of female rats aged 35 d were exposed to SHA (5460m) in a SHA chamber for 27 d (HX rats). Other group was maintained under local barometric pressure conditions (NX rats). One half of both NX and HX rats were fed a protein-free diet for the initial 9 d of the experimental period. From this time on, they were fed a diet containing 20% protein, as were the remaining rats of both groups during the entire experimental period. The growth rates of both mass and length of the body were significantly depressed in well-nourished rats exposed to SHA during the entire observation period when compared to normoxic ones. At its end, body mass and body length were 24% and 21% less in HX than in NX rats. Growth rates were negatively affected by protein restriction in both NX and HX rats. During protein recovery, they reached supernormal values in response to supernormal levels of energy intake that allowed a complete catch-up of both body mass and length. The finding that energy intake during the period of protein rehabilitation in HX rats previously stunted by protein restriction was markedly higher than in HX control ones at equal levels of hypoxia demonstrates that the degree of hypoxia does not determine directly the degree of appetite and energy intake. Furthermore, the finding that catch-up growth in the stunted HX rats returns the animal only to the stunted size appropriate for the hypoxic animal supports the hypothesis that hypoxia lowers the set-point for body mass size, which is reached by inhibition of appetite. Confirmation of the hypothesis was done by assessment of the set-point of body mass by the behavioral method of the weight threshold to hoard food. It was lowered by 17.0% in HX rats.

Economic-Oriented Stochastic Optimization in Advanced Process Control of Chemical Processes

PubMed Central

Dobos, László; Király, András; Abonyi, János

2012-01-01

Finding the optimal operating region of chemical processes is an inevitable step toward improving economic performance. Usually the optimal operating region is situated close to process constraints related to product quality or process safety requirements. Higher profit can be realized only by assuring a relatively low frequency of violation of these constraints. A multilevel stochastic optimization framework is proposed to determine the optimal setpoint values of control loops with respect to predetermined risk levels, uncertainties, and costs of violation of process constraints. The proposed framework is realized as direct search-type optimization of Monte-Carlo simulation of the controlled process. The concept is illustrated throughout by a well-known benchmark problem related to the control of a linear dynamical system and the model predictive control of a more complex nonlinear polymerization process. PMID:23213298

Swift BAT Thermal Recovery After Loop Heat Pipe #0 Secondary Heater Controller Failure in October 2015

NASA Technical Reports Server (NTRS)

Choi, Michael K.

2016-01-01

The Swift BAT LHP #0 primary heater controller failed on March 31, 2010. It has been disabled. On October 31, 2015, the secondary heater controller of this LHP failed. On November 1, 2015, the LHP #0 CC temperature increased to as 18.6 C, despite that the secondary heater controller set point was 8.8 C. It caused the average DM XA1 temperature to increase to 25.9 C, which was 5 C warmer than nominal. As a result, the detectors became noisy. To solve this problem, the LHP #1 secondary heater controller set point was decreased in 0.5 C decrements to 2.2 C. The set-point decrease restored the average DM XA1 temperature to a nominal value of 19.7 C on November 21.

Optimal Power Flow Pursuit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Simonetto, Andrea

This paper considers distribution networks featuring inverter-interfaced distributed energy resources, and develops distributed feedback controllers that continuously drive the inverter output powers to solutions of AC optimal power flow (OPF) problems. Particularly, the controllers update the power setpoints based on voltage measurements as well as given (time-varying) OPF targets, and entail elementary operations implementable onto low-cost microcontrollers that accompany power-electronics interfaces of gateways and inverters. The design of the control framework is based on suitable linear approximations of the AC power-flow equations as well as Lagrangian regularization methods. Convergence and OPF-target tracking capabilities of the controllers are analytically established. Overall,more » the proposed method allows to bypass traditional hierarchical setups where feedback control and optimization operate at distinct time scales, and to enable real-time optimization of distribution systems.« less

An on-line modified least-mean-square algorithm for training neurofuzzy controllers.

PubMed

Tan, Woei Wan

2007-04-01

The problem hindering the use of data-driven modelling methods for training controllers on-line is the lack of control over the amount by which the plant is excited. As the operating schedule determines the information available on-line, the knowledge of the process may degrade if the setpoint remains constant for an extended period. This paper proposes an identification algorithm that alleviates "learning interference" by incorporating fuzzy theory into the normalized least-mean-square update rule. The ability of the proposed methodology to achieve faster learning is examined by employing the algorithm to train a neurofuzzy feedforward controller for controlling a liquid level process. Since the proposed identification strategy has similarities with the normalized least-mean-square update rule and the recursive least-square estimator, the on-line learning rates of these algorithms are also compared.

TREAT Reactor Control and Protection System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipinski, W.C.; Brookshier, W.K.; Burrows, D.R.

1985-01-01

The main control algorithm of the Transient Reactor Test Facility (TREAT) Automatic Reactor Control System (ARCS) resides in Read Only Memory (ROM) and only experiment specific parameters are input via keyboard entry. Prior to executing an experiment, the software and hardware of the control computer is tested by a closed loop real-time simulation. Two computers with parallel processing are used for the reactor simulation and another computer is used for simulation of the control rod system. A monitor computer, used as a redundant diverse reactor protection channel, uses more conservative setpoints and reduces challenges to the Reactor Trip System (RTS).more » The RTS consists of triplicated hardwired channels with one out of three logic. The RTS is automatically tested by a digital Dedicated Microprocessor Tester (DMT) prior to the execution of an experiment. 6 refs., 5 figs., 1 tab.« less

A systems biology approach uncovers cellular strategies used by Methylobacterium extorquens AM1 during the switch from multi- to single-carbon growth.

PubMed

Skovran, Elizabeth; Crowther, Gregory J; Guo, Xiaofeng; Yang, Song; Lidstrom, Mary E

2010-11-24

When organisms experience environmental change, how does their metabolic network reset and adapt to the new condition? Methylobacterium extorquens is a bacterium capable of growth on both multi- and single-carbon compounds. These different modes of growth utilize dramatically different central metabolic pathways with limited pathway overlap. This study focused on the mechanisms of metabolic adaptation occurring during the transition from succinate growth (predicted to be energy-limited) to methanol growth (predicted to be reducing-power-limited), analyzing changes in carbon flux, gene expression, metabolites and enzymatic activities over time. Initially, cells experienced metabolic imbalance with excretion of metabolites, changes in nucleotide levels and cessation of cell growth. Though assimilatory pathways were induced rapidly, a transient block in carbon flow to biomass synthesis occurred, and enzymatic assays suggested methylene tetrahydrofolate dehydrogenase as one control point. This "downstream priming" mechanism ensures that significant carbon flux through these pathways does not occur until they are fully induced, precluding the buildup of toxic intermediates. Most metabolites that are required for growth on both carbon sources did not change significantly, even though transcripts and enzymatic activities required for their production changed radically, underscoring the concept of metabolic setpoints. This multi-level approach has resulted in new insights into the metabolic strategies carried out to effect this shift between two dramatically different modes of growth and identified a number of potential flux control and regulatory check points as a further step toward understanding metabolic adaptation and the cellular strategies employed to maintain metabolic setpoints.

Improvements to Fidelity, Generation and Implementation of Physics-Based Lithium-Ion Reduced-Order Models

NASA Astrophysics Data System (ADS)

Rodriguez Marco, Albert

Battery management systems (BMS) require computationally simple but highly accurate models of the battery cells they are monitoring and controlling. Historically, empirical equivalent-circuit models have been used, but increasingly researchers are focusing their attention on physics-based models due to their greater predictive capabilities. These models are of high intrinsic computational complexity and so must undergo some kind of order-reduction process to make their use by a BMS feasible: we favor methods based on a transfer-function approach of battery cell dynamics. In prior works, transfer functions have been found from full-order PDE models via two simplifying assumptions: (1) a linearization assumption--which is a fundamental necessity in order to make transfer functions--and (2) an assumption made out of expedience that decouples the electrolyte-potential and electrolyte-concentration PDEs in order to render an approach to solve for the transfer functions from the PDEs. This dissertation improves the fidelity of physics-based models by eliminating the need for the second assumption and, by linearizing nonlinear dynamics around different constant currents. Electrochemical transfer functions are infinite-order and cannot be expressed as a ratio of polynomials in the Laplace variable s. Thus, for practical use, these systems need to be approximated using reduced-order models that capture the most significant dynamics. This dissertation improves the generation of physics-based reduced-order models by introducing different realization algorithms, which produce a low-order model from the infinite-order electrochemical transfer functions. Physics-based reduced-order models are linear and describe cell dynamics if operated near the setpoint at which they have been generated. Hence, multiple physics-based reduced-order models need to be generated at different setpoints (i.e., state-of-charge, temperature and C-rate) in order to extend the cell operating range. This dissertation improves the implementation of physics-based reduced-order models by introducing different blending approaches that combine the pre-computed models generated (offline) at different setpoints in order to produce good electrochemical estimates (online) along the cell state-of-charge, temperature and C-rate range.

Tramadol reduces the sweating, vasoconstriction, and shivering thresholds.

PubMed

De Witte, J L; Kim, J S; Sessler, D I; Bastanmehr, H; Bjorksten, A R

1998-07-01

The analgesic tramadol inhibits the neuronal reuptake of norepinephrine and 5-hydroxytryptamine, facilitates 5-hydroxytryptamine release, and activates mu-opioid receptors. Each of these actions is likely to influence thermoregulatory control. We therefore tested the hypothesis that tramadol inhibits thermoregulatory control. Eight volunteers were evaluated on four study days, on which they received no drugs, tramadol 125 mg, tramadol 250 mg, and tramadol 250 mg with naloxone, respectively. Skin and core temperatures were gradually increased until sweating was observed and then decreased until vasoconstriction and shivering were detected. The core temperature triggering each response defined its threshold. Tramadol decreased the sweating threshold by -1.03 +/- 0.67 degrees C microgram-1.mL (r2 = 0.90 +/- 0.12). Tramadol also decreased the vasoconstriction threshold by -3.0 +/- 4.0 degrees C microgram-1.mL (r2 = 0.94 +/- 0.98) and the shivering threshold by -4.2 +/- 4.0 degrees C microgram-1.mL(r2 = 0.98 +/- 0.98). The sweating to vasoconstriction interthreshold range nearly doubled from 0.3 +/- 0.4 degree C to 0.7 +/- 0.6 degree C during the administration of large-dose tramadol (P = 0.04). The addition of naloxone only partially reversed the thermoregulatory effects of tramadol. The thermoregulatory effects of tramadol thus most resemble those of midazolam, another drug that slightly decreases the thresholds triggering all three major autonomic thermoregulatory defenses. In this respect, both drugs reduce the "setpoint" rather than produce a generalized impairment of thermoregulatory control. Nonetheless, tramadol nearly doubled the interthreshold range at a concentration near 200 ng/mL. This indicates that tramadol slightly decreases the precision of thermoregulatory control in addition to reducing the setpoint. The authors evaluated the effects of the analgesic tramadol on the three major thermoregulatory responses: sweating, vasoconstriction, and shivering. Tramadol had only slight thermoregulatory effects. Its use is thus unlikely to provoke hypothermia or to facilitate fever.

Response Time Analysis and Test of Protection System Instrument Channels for APR1400 and OPR1000

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Chang Jae; Han, Seung; Yun, Jae Hee

2015-07-01

Safety limits are required to maintain the integrity of physical barriers designed to prevent the uncontrolled release of radioactive materials in nuclear power plants. The safety analysis establishes two critical constraints that include an analytical limit in terms of a measured or calculated variable, and a specific time after the analytical limit is reached to begin protective action. Keeping with the nuclear regulations and industry standards, satisfying these two requirements will ensure that the safety limit will not be exceeded during the design basis event, either an anticipated operational occurrence or a postulated accident. Various studies on the setpoint determinationmore » methodology for the safety-related instrumentation have been actively performed to ensure that the requirement of the analytical limit is satisfied. In particular, the protection setpoint methodology for the advanced power reactor 1400 (APP1400) and the optimized power reactor 1000 (OPR1000) has been recently developed to cover both the design basis event and the beyond design basis event. The developed setpoint methodology has also been quantitatively validated using specific computer programs and setpoint calculations. However, the safety of nuclear power plants cannot be fully guaranteed by satisfying the requirement of the analytical limit. In spite of the response time verification requirements of nuclear regulations and industry standards, it is hard to find the studies on the systematically integrated methodology regarding the response time evaluation. In cases of APR1400 and OPR1000, the response time analysis for the plant protection system is partially included in the setpoint calculation and the response time test is separately performed via the specific plant procedure. The test technique has a drawback which is the difficulty to demonstrate completeness of timing test. The analysis technique has also a demerit of resulting in extreme times that not actually possible. Thus, the establishment of the systematic response time evaluation methodology is needed to justify the conformance to the response time requirement used in the safety analysis. This paper proposes the response time evaluation methodology for APR1400 and OPR1000 using the combined analysis and test technique to confirm that the plant protection system can meet the analytical response time assumed in the safety analysis. In addition, the results of the quantitative evaluation performed for APR1400 and OPR1000 are presented in this paper. The proposed response time analysis technique consists of defining the response time requirement, determining the critical signal path for the trip parameter, allocating individual response time to each component on the signal path, and analyzing the total response time for the trip parameter, and demonstrates that the total analyzed response time does not exceed the response time requirement. The proposed response time test technique is composed of defining the response time requirement, determining the critical signal path for the trip parameter, determining the test method for each component on the signal path, performing the response time test, and demonstrates that the total test result does not exceed the response time requirement. The total response time should be tested in a single test that covers from the sensor to the final actuation device on the instrument channel. When the total channel is not tested in a single test, separate tests on groups of components or single components including the total instrument channel shall be combined to verify the total channel response. For APR1400 and OPR1000, the ramp test technique is used for the pressure and differential pressure transmitters and the step function testing technique is applied to the signal processing equipment and final actuation device. As a result, it can be demonstrated that the response time requirement is satisfied by the combined analysis and test technique. Therefore, the proposed methodology in this paper plays a crucial role in guaranteeing the safety of the nuclear power plants systematically satisfying one of two critical requirements from the safety analysis. (authors)« less

Unified dead-time compensation structure for SISO processes with multiple dead times.

PubMed

Normey-Rico, Julio E; Flesch, Rodolfo C C; Santos, Tito L M

2014-11-01

This paper proposes a dead-time compensation structure for processes with multiple dead times. The controller is based on the filtered Smith predictor (FSP) dead-time compensator structure and it is able to control stable, integrating, and unstable processes with multiple input/output dead times. An equivalent model of the process is first computed in order to define the predictor structure. Using this equivalent model, the primary controller and the predictor filter are tuned to obtain an internally stable closed-loop system which also attempts some closed-loop specifications in terms of set-point tracking, disturbance rejection, and robustness. Some simulation case studies are used to illustrate the good properties of the proposed approach. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Imaging contrast and tip-sample interaction of non-contact amplitude modulation atomic force microscopy with Q-control

NASA Astrophysics Data System (ADS)

Shi, Shuai; Guo, Dan; Luo, Jianbin

2017-10-01

Active quality factor (Q) exhibits many promising properties in dynamic atomic force microscopy. Energy dissipation and image contrasts are investigated in the non-contact amplitude modulation atomic force microscopy (AM-AFM) with an active Q-control circuit in the ambient air environment. Dissipated power and virial were calculated to compare the highly nonlinear interaction of tip-sample and image contrasts with different Q gain values. Greater free amplitudes and lower effective Q values show better contrasts for the same setpoint ratio. Active quality factor also can be employed to change tip-sample interaction force in non-contact regime. It is meaningful that non-destructive and better contrast images can be realized in non-contact AM-AFM by applying an active Q-control to the dynamic system.

Combination of Methoprene and Controlled Aeration to Manage Insects in Stored Wheat.

PubMed

Liu, Samuel S; Arthur, Frank H; VanGundy, Douglas; Phillips, Thomas W

2016-06-17

A commercial formulation of the insect growth regulator methoprene was applied to wheat stored in small bins either alone or in combination with controlled aeration of the bins, to lower grain temperature for insect pest management of stored wheat. Grain temperatures were monitored and modified by a computer-controlled thermocouple system that also activated the aeration system at programmed set-points to move cool ambient air through the grain mass to lower grain temperature. Results from sampling insect populations in experimental storage bins along with laboratory mortality bioassays of insects placed on wheat taken from the bins over the course of the storage period showed that methoprene was very effective in controlling infestation by the externally-feeding stored grain insects Plodia interpunctella (Hübner), the Indian meal moth Tribolium castaneum (Herbst), the red flour beetle, Cryptolestes ferrugineus (Stephens), the rusty grain beetle, and also for the internal-feeding pest Rhyzopertha dominica( Fauvel), the lesser grain borer. Methoprene did not give good control of the internal-feeding pest Sitophilus oryzae (L.), the rice weevil. Aeration alone was somewhat effective in suppressing insect population development, while methoprene alone or when combined with aeration greatly enhanced insect control. Commercial grain grading for industry quality standards at the end of the storage period confirmed the impact of insect suppression on maintaining high quality of the stored wheat. This field experiment shows that methoprene combined with aeration to cool grain can be effective for pest management of stored wheat in the southern plains of the United States of America.

Hybrid intelligent control of substrate feeding for industrial fed-batch chlortetracycline fermentation process.

PubMed

Jin, Huaiping; Chen, Xiangguang; Yang, Jianwen; Wu, Lei; Wang, Li

2014-11-01

The lack of accurate process models and reliable online sensors for substrate measurements poses significant challenges for controlling substrate feeding accurately, automatically and optimally in fed-batch fermentation industries. It is still a common practice to regulate the feeding rate based upon manual operations. To address this issue, a hybrid intelligent control method is proposed to enable automatic substrate feeding. The resulting control system consists of three modules: a presetting module for providing initial set-points; a predictive module for estimating substrate concentration online based on a new time interval-varying soft sensing algorithm; and a feedback compensator using expert rules. The effectiveness of the proposed approach is demonstrated through its successful applications to the industrial fed-batch chlortetracycline fermentation process. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Using Dynamic Simulation to Evaluate Attemperator Operation in a Natural Gas Combined Cycle With Duct Burners in the Heat Recovery Steam Generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liese, Eric; Zitney, Stephen E.

A generic training simulator of a natural gas combined cycle was modified to match operations at a real plant. The objective was to use the simulator to analyze cycling operations of the plant. Initial operation of the simulator revealed the potential for saturation conditions in the final high pressure superheater as the attemperator tried to control temperature at the superheater outlet during gas turbine loading and unloading. Subsequent plant operational data confirmed simulation results. Multiple simulations were performed during loading and unloading of the gas turbine to determine operational strategies that prevented saturation and increased the approach to saturation temperature.more » The solutions included changes to the attemperator temperature control setpoints and strategic control of the steam turbine inlet pressure control valve.« less

Coordinated Dynamic Behaviors for Multirobot Systems With Collision Avoidance.

PubMed

Sabattini, Lorenzo; Secchi, Cristian; Fantuzzi, Cesare

2017-12-01

In this paper, we propose a novel methodology for achieving complex dynamic behaviors in multirobot systems. In particular, we consider a multirobot system partitioned into two subgroups: 1) dependent and 2) independent robots. Independent robots are utilized as a control input, and their motion is controlled in such a way that the dependent robots solve a tracking problem, that is following arbitrarily defined setpoint trajectories, in a coordinated manner. The control strategy proposed in this paper explicitly addresses the collision avoidance problem, utilizing a null space-based behavioral approach: this leads to combining, in a non conflicting manner, the tracking control law with a collision avoidance strategy. The combination of these control actions allows the robots to execute their task in a safe way. Avoidance of collisions is formally proven in this paper, and the proposed methodology is validated by means of simulations and experiments on real robots.

Deep Space One High-Voltage Bus Management

NASA Technical Reports Server (NTRS)

Rachocki, Ken; Nieraeth, Donald

1999-01-01

The design of the High Voltage Power Converter Unit on DS1 allows both the spacecraft avionics and ion propulsion to operate in a stable manner near the PPP of the solar array. This approach relies on a fairly well-defined solar array model to determine the projected PPP. The solar array voltage set-points have to be updated every week to maintain operation near PPP. Stable operation even to the LEFT of the Peak Power Point is achievable so long as you do not change the operating power level of the ion engine. The next step for this technology is to investigate the use of onboard autonomy to determine the optimum SA voltage regulation set-point (i.e. near the PPP); this is for future missions that have one or more ion propulsion subsystems.

Thermal analysis of HGFQ using FIDAP(trademark): Solidification front motion

NASA Technical Reports Server (NTRS)

Woodbury, Keith A.

1996-01-01

The High Gradient Furnace with Quench (HGFQ) is being designed by NASA/MSFC for flight on the International Space Station. The furnace is being designed specifically for solidification experiments in metal and metallic alloy systems. The HGFQ Product development Team (PDT) has been active since January 1994 and their effort is now in early Phase B. Thermal models have been developed both by NASA and Sverdrup (support contractor) to assist in the HGFQ design effort. Both these models use SINDA as a solution engine, but the NASA model was developed using PATRAN and includes more detail than the Sverdrup model. These models have been used to guide design decisions and have been validated through experimentation on a prototypical 'Breadboard' furnace at MSFC. One facet of the furnace operation of interest to the designers is the sensitivity of the solidification interface location to changes in the furnace setpoint. Specifically of interest is the motion (position and velocity) of the solidification front due to a small perturbation in the furnace temperature. FIDAP(TM) is a commercially available finite element program for analysis of heat transfer and fluid flow processes. Its strength is in solution of the Navier-Stokes equations for incompressible flow, but among its capabilities is the analysis of transient processes involving radiation and solidification. The models presently available from NASA and Sverdrup are steady-state models and are incapable of computing the motion of the solidification front. The objective of this investigation is to use FIDAP(TM) to compute the motion of the solidification interface due to a perturbation in the furnace setpoint.

A genuine nonlinear approach for controller design of a boiler-turbine system.

PubMed

Yang, Shizhong; Qian, Chunjiang; Du, Haibo

2012-05-01

This paper proposes a genuine nonlinear approach for controller design of a drum-type boiler-turbine system. Based on a second order nonlinear model, a finite-time convergent controller is first designed to drive the states to their setpoints in a finite time. In the case when the state variables are unmeasurable, the system will be regulated using a constant controller or an output feedback controller. An adaptive controller is also designed to stabilize the system since the model parameters may vary under different operating points. The novelty of the proposed controller design approach lies in fully utilizing the system nonlinearities instead of linearizing or canceling them. In addition, the newly developed techniques for finite-time convergent controller are used to guarantee fast convergence of the system. Simulations are conducted under different cases and the results are presented to illustrate the performance of the proposed controllers. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

A Systems Biology Approach Uncovers Cellular Strategies Used by Methylobacterium extorquens AM1 During the Switch from Multi- to Single-Carbon Growth

PubMed Central

Skovran, Elizabeth; Crowther, Gregory J.; Guo, Xiaofeng; Yang, Song; Lidstrom, Mary E.

2010-01-01

Background When organisms experience environmental change, how does their metabolic network reset and adapt to the new condition? Methylobacterium extorquens is a bacterium capable of growth on both multi- and single-carbon compounds. These different modes of growth utilize dramatically different central metabolic pathways with limited pathway overlap. Methodology/Principal Findings This study focused on the mechanisms of metabolic adaptation occurring during the transition from succinate growth (predicted to be energy-limited) to methanol growth (predicted to be reducing-power-limited), analyzing changes in carbon flux, gene expression, metabolites and enzymatic activities over time. Initially, cells experienced metabolic imbalance with excretion of metabolites, changes in nucleotide levels and cessation of cell growth. Though assimilatory pathways were induced rapidly, a transient block in carbon flow to biomass synthesis occurred, and enzymatic assays suggested methylene tetrahydrofolate dehydrogenase as one control point. This “downstream priming” mechanism ensures that significant carbon flux through these pathways does not occur until they are fully induced, precluding the buildup of toxic intermediates. Most metabolites that are required for growth on both carbon sources did not change significantly, even though transcripts and enzymatic activities required for their production changed radically, underscoring the concept of metabolic setpoints. Conclusions/Significance This multi-level approach has resulted in new insights into the metabolic strategies carried out to effect this shift between two dramatically different modes of growth and identified a number of potential flux control and regulatory check points as a further step toward understanding metabolic adaptation and the cellular strategies employed to maintain metabolic setpoints. PMID:21124828

Biomass Production System (BPS) plant growth unit.

PubMed

Morrow, R C; Crabb, T M

2000-01-01

The Biomass Production System (BPS) was developed under the Small Business Innovative Research (SBIR) program to meet science, biotechnology and commercial plant growth needs in the Space Station era. The BPS is equivalent in size to a double middeck locker, but uses its own custom enclosure with a slide out structure to which internal components mount. The BPS contains four internal growth chambers, each with a growing volume of more than 4 liters. Each of the growth chambers has active nutrient delivery, and independent control of temperature, humidity, lighting, and CO2 set-points. Temperature control is achieved using a thermoelectric heat exchanger system. Humidity control is achieved using a heat exchanger with a porous interface which can both humidify and dehumidify. The control software utilizes fuzzy logic for nonlinear, coupled temperature and humidity control. The fluorescent lighting system can be dimmed to provide a range of light levels. CO2 levels are controlled by injecting pure CO2 to the system based on input from an infrared gas analyzer. The unit currently does not scrub CO2, but has been designed to accept scrubber cartridges. In addition to providing environmental control, a number of features are included to facilitate science. The BPS chambers are sealed to allow CO2 and water vapor exchange measurements. The plant chambers can be removed to allow manipulation or sampling of specimens, and each chamber has gas/fluid sample ports. A video camera is provided for each chamber, and frame-grabs and complete environmental data for all science and hardware system sensors are stored on an internal hard drive. Data files can also be transferred to 3.5-inch disks using the front panel disk drive.

Biomass Production System (BPS) Plant Growth Unit

NASA Astrophysics Data System (ADS)

Morrow, R. C.; Crabb, T. M.

The Biomass Production System (BPS) was developed under the Small Business Innovative Research (SBIR) program to meet science, biotechnology and commercial plant growth needs in the Space Station era. The BPS is equivalent in size to a double middeck locker, but uses it's own custom enclosure with a slide out structure to which internal components mount. The BPS contains four internal growth chambers, each with a growing volume of more than 4 liters. Each of the growth chambers has active nutrient delivery, and independent control of temperature, humidity, lighting, and CO2 set-points. Temperature control is achieved using a thermoelectric heat exchanger system. Humidity control is achieved using a heat exchanger with a porous interface which can both humidify and dehumidify. The control software utilizes fuzzy logic for nonlinear, coupled temperature and humidity control. The fluorescent lighting system can be dimmed to provide a range of light levels. CO2 levels are controlled by injecting pure CO2 to the system based on input from an infrared gas analyzer. The unit currently does not scrub CO2, but has been designed to accept scrubber cartridges. In addition to providing environmental control, a number of features are included to facilitate science. The BPS chambers are sealed to allow CO2 and water vapor exchange measurements. The plant chambers can be removed to allow manipulation or sampling of specimens, and each chamber has gas/fluid sample ports. A video camera is provided for each chamber, and frame-grabs and complete environmental data for all science and hardware system sensors are stored on an internal hard drive. Data files can also be transferred to 3.5-inch disks using the front panel disk drive

Enhanced polyhydroxyalkanoate production from organic wastes via process control.

PubMed

Vargas, Alejandro; Montaño, Liliana; Amaya, Rodolfo

2014-03-01

This work explores the use of a model-based control scheme to enhance the productivity of polyhroxyalkanoate (PHA) production in a mixed culture two-stage system fed with synthetic wastewater. The controller supplies pulses of substrate while regulating the dissolved oxygen (DO) concentration and uses the data to fit a dynamic mathematical model, which in turn is used to predict the time until the next pulse addition. Experiments in a bench scale system first determined the optimal DO set-point and initial substrate concentration. Then the proposed feedback control strategy was compared with a simpler empiric algorithm. The results show that a substrate conversion rate of 1.370±0.598mgPHA/mgCOD/d was achieved. The proposed strategy can also indicate when to stop the accumulation of PHA upon saturation, which occurred with a PHA content of 71.0±7.2wt.%. Copyright © 2014 Elsevier Ltd. All rights reserved.

Tuning rules for robust FOPID controllers based on multi-objective optimization with FOPDT models.

PubMed

Sánchez, Helem Sabina; Padula, Fabrizio; Visioli, Antonio; Vilanova, Ramon

2017-01-01

In this paper a set of optimally balanced tuning rules for fractional-order proportional-integral-derivative controllers is proposed. The control problem of minimizing at once the integrated absolute error for both the set-point and the load disturbance responses is addressed. The control problem is stated as a multi-objective optimization problem where a first-order-plus-dead-time process model subject to a robustness, maximum sensitivity based, constraint has been considered. A set of Pareto optimal solutions is obtained for different normalized dead times and then the optimal balance between the competing objectives is obtained by choosing the Nash solution among the Pareto-optimal ones. A curve fitting procedure has then been applied in order to generate suitable tuning rules. Several simulation results show the effectiveness of the proposed approach. Copyright © 2016. Published by Elsevier Ltd.

Gravity response mechanisms of lateral organs and the control of plant architecture in Arabidopsis

NASA Astrophysics Data System (ADS)

Mullen, J.; Hangarter, R.

Most research on gravity responses in plants has focused on primary roots and shoots, which typically grow in a vertical orientation. However, the patterns of lateral organ formation and their growth orientation, which typically are not vertical, govern plant architecture. For example, in Arabidopsis, when lateral roots emerge from the primary root, they grow at a nearly horizontal orientation. As they elongate, the roots slowly curve until they eventually reach a vertical orientation. The regulation of this lateral root orientation is an important component affecting the overall root system architecture. We have found that this change in orientation is not simply due to the onset of gravitropic competence, as non-vertical lateral roots are capable of both positive and negative gravitropism. Thus, the horizontal growth of the new lateral roots is determined by what is called the gravitropic set-point angle (GSA). In Arabidopsis shoots, rosette leaves and inflorescence branches also display GSA-dependent developmental changes in their orientation. The developmental control of the GSA of lateral organs in Arabidopsis provides us with a useful system for investigating the components involved in regulating directionality of tropistic responses. We have identified several Arabidopsis mutants that have either altered lateral root orientations, altered orientation of lateral organs in the shoot, or both, but maintain normal primary organ orientation. The mgsa ({m}odified {g}ravitropic {s}et-point {a}ngle) mutants with both altered lateral root and shoot orientation show that there are common components in the regulation of growth orientation in the different organs. Rosette leaves and lateral roots also have in common a regulation of positioning by red light. Further molecular and physiological analyses of the GSA mutants will provide insight into the basis of GSA regulation and, thus, a better understanding of how gravity controls plant architecture. [This work was supported by the National Aeronautics and Space Administration through grant no. NCC 2-1200.

Geoscience Laser Altimetry System (GLAS) Loop Heat Pipe Anomaly and On Orbit Testing

NASA Technical Reports Server (NTRS)

Baker, Charles; Butler, Dan; Grob, Eric; Jester, Peggy

2011-01-01

The Geoscience Laser Altimetry System (GLAS) is the sole instrument on the ICESat Satellite. On day 230 of 2003, the GLAS Component Loop Heat Pipe (CLHP) entered a slow circulation mode that resulted in the main electronics box reaching its hot safing temperature, after which the entire instrument was turned off. The CLHP had a propylene working fluid and was actively temperature controlled via a heater on the compensation chamber. The slow circulation mode happened right after a planned propulsive yaw maneuver with the spacecraft. It took several days to recover the CLHP and ensure that it was still operational. The recovery occurred after the entire instrument was cooled to survival temperatures and the CLHP compensation chamber cycled on a survival heater. There are several theories as to why this slow circulation mode exhibited itself, including: accumulation of Non-Condensible Gas (NCG), the secondary wick being under designed or improperly implemented, or an expanded (post-launch) leak across the primary wick. Each of these is discussed in turn, and the secondary wick performance is identified as the most likely source of the anomalous behavior. After the anomaly, the CLHP was controlled to colder temperatures to improve its performance (as the surface tension increases with lower temperature, as does the volume of liquid in the compensation chamber) and only precursor pulses occurred later in the mission. After GLAS s last laser failed, in late 2009, a decision was made to conduct engineering tests of both LHPs to try and duplicate this flight anomaly. The engineering tests consisted of control setpoint changes, sink changes, and one similar propulsive Yaw maneuver. The only test that showed any similar anomaly precursors on the CLHP was the propulsive maneuver followed by a setpoint increase. The ICESat Satellite was placed in a decaying orbit and ended its mission on August 30, 2010 in Barents Sea.

Low-temperature overpressurization protection system setpoint analysis using RETRAN-02/MOD5 for Salem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodson, R.J.; Feltus, M.A.

The low-temperature overpressurization protection system (LTOPS) is designed to protect the reactor pressure vessel (RPV) from brittle failure during startup and cooldown maneuvers in Westinghouse pressurized water reactors. For the Salem power plants, the power-operated relief valves (PORVs) mitigate pressure increases above a setpoint where an operational startup transient may put the RPV in the embrittlement fracture zone. The Title 10, Part 50, Code of Federal Regulations Appendix G limit, given by plant technical specifications, conservatively bounds the maximum pressure allowed during those transients where the RPV can suffer brittle fracture (usually below 350{degrees}F). The Appendix G limit is amore » pressure versus temperature curve that is more restrictive at lower RPV temperatures and allows for higher pressures as the temperature approaches the upper bounding fracture temperature.« less

Robust interval-based regulation for anaerobic digestion processes.

PubMed

Alcaraz-González, V; Harmand, J; Rapaport, A; Steyer, J P; González-Alvarez, V; Pelayo-Ortiz, C

2005-01-01

A robust regulation law is applied to the stabilization of a class of biochemical reactors exhibiting partially known highly nonlinear dynamic behavior. An uncertain environment with the presence of unknown inputs is considered. Based on some structural and operational conditions, this regulation law is shown to exponentially stabilize the aforementioned bioreactors around a desired set-point. This approach is experimentally applied and validated on a pilot-scale (1 m3) anaerobic digestion process for the treatment of raw industrial wine distillery wastewater where the objective is the regulation of the chemical oxygen demand (COD) by using the dilution rate as the manipulated variable. Despite large disturbances on the input COD and state and parametric uncertainties, this regulation law gave excellent performances leading the output COD towards its set-point and keeping it inside a pre-specified interval.

Rapid determination of vial heat transfer parameters using tunable diode laser absorption spectroscopy (TDLAS) in response to step-changes in pressure set-point during freeze-drying.

PubMed

Kuu, Wei Y; Nail, Steven L; Sacha, Gregory

2009-03-01

The purpose of this study was to perform a rapid determination of vial heat transfer parameters, that is, the contact parameter K(cs) and the separation distance l(v), using the sublimation rate profiles measured by tunable diode laser absorption spectroscopy (TDLAS). In this study, each size of vial was filled with pure water followed by a freeze-drying cycle using a LyoStar II dryer (FTS Systems) with step-changes of the chamber pressure set-point at to 25, 50, 100, 200, 300, and 400 mTorr. K(cs) was independently determined by nonlinear parameter estimation using the sublimation rates measured at the pressure set-point of 25 mTorr. After obtaining K(cs), the l(v) value for each vial size was determined by nonlinear parameter estimation using the pooled sublimation rate profiles obtained at 25 to 400 mTorr. The vial heat transfer coefficient K(v), as a function of the chamber pressure, was readily calculated, using the obtained K(cs) and l(v) values. It is interesting to note the significant difference in K(v) of two similar types of 10 mL Schott tubing vials, primary due to the geometry of the vial-bottom, as demonstrated by the images of the contact areas of the vial-bottom. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

The influence of hypoxia on the thermal sensitivity of skin colouration in the bearded dragon, Pogona vitticeps.

PubMed

de Velasco, Jesus Barraza; Tattersall, Glenn J

2008-09-01

One physiological mechanism used by reptiles to remain within thermal optima is their ability to reversibly alter skin colour, imparting changes in overall reflectance, and influencing the rate of heat gain from incident radiation. The ability to lighten or darken their skin is caused by the movement of pigment within the dermal chromatophore cells. Additionally, lizards, as ectotherms, significantly lower their preferred body temperatures when experiencing stressors such as hypoxia. This decrease in preferred temperature has been proposed to be the result of a downward adjustment of the thermal set-point, the temperature around which the body temperature is typically defended. We tested the hypothesis that lightening of the skin in lizards would be modified by hypoxia in a manner consistent with the known reduction in preferred temperatures. Skin colouration values of the dorsal skin of bearded dragons were analysed at three different levels of oxygen (20.8, 9.9 and 4.9 kPa) and at temperatures spanning the preferred temperature range (30, 32, 34, 36, 38 and 40 C). Hypoxic lizards lightened their skin at lower ambient temperatures more than normoxic ones, and in an oxygen-dependent fashion. The orchestrated adjustment of skin reflectance suggests that this physiological trait is being regulated at a new and lower set-point. Evidence from this study demonstrates that skin colouration plays a role in body temperature regulation and that the reduction in temperature set-point so prevalent in hypoxia is also manifested in this physiological trait.

Eigenstrain as a mechanical set-point of cells.

PubMed

Lin, Shengmao; Lampi, Marsha C; Reinhart-King, Cynthia A; Tsui, Gary; Wang, Jian; Nelson, Carl A; Gu, Linxia

2018-02-05

Cell contraction regulates how cells sense their mechanical environment. We sought to identify the set-point of cell contraction, also referred to as tensional homeostasis. In this work, bovine aortic endothelial cells (BAECs), cultured on substrates with different stiffness, were characterized using traction force microscopy (TFM). Numerical models were developed to provide insights into the mechanics of cell-substrate interactions. Cell contraction was modeled as eigenstrain which could induce isometric cell contraction without external forces. The predicted traction stresses matched well with TFM measurements. Furthermore, our numerical model provided cell stress and displacement maps for inspecting the fundamental regulating mechanism of cell mechanosensing. We showed that cell spread area, traction force on a substrate, as well as the average stress of a cell were increased in response to a stiffer substrate. However, the cell average strain, which is cell type-specific, was kept at the same level regardless of the substrate stiffness. This indicated that the cell average strain is the tensional homeostasis that each type of cell tries to maintain. Furthermore, cell contraction in terms of eigenstrain was found to be the same for both BAECs and fibroblast cells in different mechanical environments. This implied a potential mechanical set-point across different cell types. Our results suggest that additional measurements of contractility might be useful for monitoring cell mechanosensing as well as dynamic remodeling of the extracellular matrix (ECM). This work could help to advance the understanding of the cell-ECM relationship, leading to better regenerative strategies.

Management of laser welding based on analysis informative signals

NASA Astrophysics Data System (ADS)

Zvezdin, V. V.; Rakhimov, R. R.; Saubanov, Ruz R.; Israfilov, I. H.; Akhtiamov, R. F.

2017-09-01

Features of formation precision weld of metal were presented. It has been shown that the quality of the welding process depends not only on the energy characteristics of the laser processing facility, the temperature of the surface layer, but also on the accuracy of positioning laser focus relative to seam and the workpiece surface. So the laser focus positioning accuracy is an estimate of the quality of the welding process. This approach allows to build a system automated control of the laser technological complex with the stabilization of the setpoint accuracy of of positioning of the laser beam relative to the workpiece surface.

Quick generation of Raman spectroscopy based in-process glucose control to influence biopharmaceutical protein product quality during mammalian cell culture.

PubMed

Berry, Brandon N; Dobrowsky, Terrence M; Timson, Rebecca C; Kshirsagar, Rashmi; Ryll, Thomas; Wiltberger, Kelly

2016-01-01

Mitigating risks to biotherapeutic protein production processes and products has driven the development of targeted process analytical technology (PAT); however implementing PAT during development without significantly increasing program timelines can be difficult. The development of a monoclonal antibody expressed in a Chinese hamster ovary (CHO) cell line via fed-batch processing presented an opportunity to demonstrate capabilities of altering percent glycated protein product. Glycation is caused by pseudo-first order, non-enzymatic reaction of a reducing sugar with an amino group. Glucose is the highest concentration reducing sugar in the chemically defined media (CDM), thus a strategy controlling glucose in the production bioreactor was developed utilizing Raman spectroscopy for feedback control. Raman regions for glucose were determined by spiking studies in water and CDM. Calibration spectra were collected during 8 bench scale batches designed to capture a wide glucose concentration space. Finally, a PLS model capable of translating Raman spectra to glucose concentration was built using the calibration spectra and spiking study regions. Bolus feeding in mammalian cell culture results in wide glucose concentration ranges. Here we describe the development of process automation enabling glucose setpoint control. Glucose-free nutrient feed was fed daily, however glucose stock solution was fed as needed according to online Raman measurements. Two feedback control conditions were executed where glucose was controlled at constant low concentration or decreased stepwise throughout. Glycation was reduced from ∼9% to 4% using a low target concentration but was not reduced in the stepwise condition as compared to the historical bolus glucose feeding regimen. © 2015 American Institute of Chemical Engineers.

Analysis of PV Advanced Inverter Functions and Setpoints under Time Series Simulation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seuss, John; Reno, Matthew J.; Broderick, Robert Joseph

Utilities are increasingly concerned about the potential negative impacts distributed PV may have on the operational integrity of their distribution feeders. Some have proposed novel methods for controlling a PV system's grid - tie inverter to mitigate poten tial PV - induced problems. This report investigates the effectiveness of several of these PV advanced inverter controls on improving distribution feeder operational metrics. The controls are simulated on a large PV system interconnected at several locations within two realistic distribution feeder models. Due to the time - domain nature of the advanced inverter controls, quasi - static time series simulations aremore » performed under one week of representative variable irradiance and load data for each feeder. A para metric study is performed on each control type to determine how well certain measurable network metrics improve as a function of the control parameters. This methodology is used to determine appropriate advanced inverter settings for each location on the f eeder and overall for any interconnection location on the feeder.« less

Reference governors for controlled belt restraint systems

NASA Astrophysics Data System (ADS)

van der Laan, E. P.; Heemels, W. P. M. H.; Luijten, H.; Veldpaus, F. E.; Steinbuch, M.

2010-07-01

Today's restraint systems typically include a number of airbags, and a three-point seat belt with load limiter and pretensioner. For the class of real-time controlled restraint systems, the restraint actuator settings are continuously manipulated during the crash. This paper presents a novel control strategy for these systems. The control strategy developed here is based on a combination of model predictive control and reference management, in which a non-linear device - a reference governor (RG) - is added to a primal closed-loop controlled system. This RG determines an optimal setpoint in terms of injury reduction and constraint satisfaction by solving a constrained optimisation problem. Prediction of the vehicle motion, required to predict future constraint violation, is included in the design and is based on past crash data, using linear regression techniques. Simulation results with MADYMO models show that, with ideal sensors and actuators, a significant reduction (45%) of the peak chest acceleration can be achieved, without prior knowledge of the crash. Furthermore, it is shown that the algorithms are sufficiently fast to be implemented online.

Nonlinear predictive control of a boiler-turbine unit: A state-space approach with successive on-line model linearisation and quadratic optimisation.

PubMed

Ławryńczuk, Maciej

2017-03-01

This paper details development of a Model Predictive Control (MPC) algorithm for a boiler-turbine unit, which is a nonlinear multiple-input multiple-output process. The control objective is to follow set-point changes imposed on two state (output) variables and to satisfy constraints imposed on three inputs and one output. In order to obtain a computationally efficient control scheme, the state-space model is successively linearised on-line for the current operating point and used for prediction. In consequence, the future control policy is easily calculated from a quadratic optimisation problem. For state estimation the extended Kalman filter is used. It is demonstrated that the MPC strategy based on constant linear models does not work satisfactorily for the boiler-turbine unit whereas the discussed algorithm with on-line successive model linearisation gives practically the same trajectories as the truly nonlinear MPC controller with nonlinear optimisation repeated at each sampling instant. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

L-Band High Power Amplifiers for CEBAF Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fugitt, Jock; Killion, Richard; Nelson, Richard

1990-09-01

The high power portion of the CEBAF RF system utilizes 340 5kW klystrons providing 339 separately controlled outputs. Modulating anodes have been included in the klystron design to provide for economically efficient operation. The design includes shunt regulator-type modulating anode power supplies running from the cathode power supply, and switching filament power supplies. Remotely programmable filament voltage allows maximum cathode life to be realized. Klystron operating setpoint and fast klystron protection logic are provided by individual external CEBAF RF control modules. A single cathode power supply powers a block of eight klystrons. The design includes circulators and custom extrusion andmore » hybrid waveguide components which have allowed reduced physical size and lower cost in the design of the WR-650 waveguide transmission system.« less

Experimental comparison of conventional and nonlinear model-based control of a mixing tank

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haeggblom, K.E.

1993-11-01

In this case study concerning control of a laboratory-scale mixing tank, conventional multiloop single-input single-output (SISO) control is compared with model-based'' control where the nonlinearity and multivariable characteristics of the process are explicitly taken into account. It is shown, especially if the operating range of the process is large, that the two outputs (level and temperature) cannot be adequately controlled by multiloop SISO control even if gain scheduling is used. By nonlinear multiple-input multiple-output (MIMO) control, on the other hand, very good control performance is obtained. The basic approach to nonlinear control used in this study is first to transformmore » the process into a globally linear and decoupled system, and then to design controllers for this system. Because of the properties of the resulting MIMO system, the controller design is very easy. Two nonlinear control system designs based on a steady-state and a dynamic model, respectively, are considered. In the dynamic case, both setpoint tracking and disturbance rejection can be addressed separately.« less

Multi-load Groups Coordinated Load Control Strategy Considering Power Network Constraints

NASA Astrophysics Data System (ADS)

Liu, Meng; Zhao, Binchao; Wang, Jun; Zhang, Guohui; Wang, Xin

2017-05-01

Loads with energy storage property can actively participate in power balance for power systems, this paper takes air conditioner as a controllable load example, proposing a multi-load groups coordinated load control strategy considering power network constraints. Firstly, two load control modes considering recovery of load diversity are designed, blocking power oscillation of aggregated air conditioners. As the same time, air conditioner temperature setpoint recovery control strategy is presented to avoid power recovery peak. Considering inherent characteristics of two load control modes, an coordinated load control mode is designed by combining the both. Basing on this, a multi-load groups coordinated load control strategy is proposed. During the implementing of load control, power network constraints should be satisfied. An indice which can reflect the security of power system operating is defined. By minimizing its value through optimization, the change of air conditioning loads’ aggregated power on each load bus can be calculated. Simulations are conducted on an air conditioners group and New England 10-generator 39-bus system, verifying the effectiveness of the proposed multi-load groups coordinated load control strategy considering power network constraints.

Design of Distributed Controllers Seeking Optimal Power Flow Solutions Under Communication Constraints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Simonetto, Andrea; Dhople, Sairaj

This paper focuses on power distribution networks featuring inverter-interfaced distributed energy resources (DERs), and develops feedback controllers that drive the DER output powers to solutions of time-varying AC optimal power flow (OPF) problems. Control synthesis is grounded on primal-dual-type methods for regularized Lagrangian functions, as well as linear approximations of the AC power-flow equations. Convergence and OPF-solution-tracking capabilities are established while acknowledging: i) communication-packet losses, and ii) partial updates of control signals. The latter case is particularly relevant since it enables asynchronous operation of the controllers where DER setpoints are updated at a fast time scale based on local voltagemore » measurements, and information on the network state is utilized if and when available, based on communication constraints. As an application, the paper considers distribution systems with high photovoltaic integration, and demonstrates that the proposed framework provides fast voltage-regulation capabilities, while enabling the near real-time pursuit of solutions of AC OPF problems.« less

Design of Distributed Controllers Seeking Optimal Power Flow Solutions under Communication Constraints: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Simonetto, Andrea; Dhople, Sairaj

This paper focuses on power distribution networks featuring inverter-interfaced distributed energy resources (DERs), and develops feedback controllers that drive the DER output powers to solutions of time-varying AC optimal power flow (OPF) problems. Control synthesis is grounded on primal-dual-type methods for regularized Lagrangian functions, as well as linear approximations of the AC power-flow equations. Convergence and OPF-solution-tracking capabilities are established while acknowledging: i) communication-packet losses, and ii) partial updates of control signals. The latter case is particularly relevant since it enables asynchronous operation of the controllers where DER setpoints are updated at a fast time scale based on local voltagemore » measurements, and information on the network state is utilized if and when available, based on communication constraints. As an application, the paper considers distribution systems with high photovoltaic integration, and demonstrates that the proposed framework provides fast voltage-regulation capabilities, while enabling the near real-time pursuit of solutions of AC OPF problems.« less

Development of Low-Cost Microcontroller-Based Interface for Data Acquisition and Control of Microbioreactor Operation.

PubMed

Husain, Abdul Rashid; Hadad, Yaser; Zainal Alam, Muhd Nazrul Hisham

2016-10-01

This article presents the development of a low-cost microcontroller-based interface for a microbioreactor operation. An Arduino MEGA 2560 board with 54 digital input/outputs, including 15 pulse-width-modulation outputs, has been chosen to perform the acquisition and control of the microbioreactor. The microbioreactor (volume = 800 µL) was made of poly(dimethylsiloxane) and poly(methylmethacrylate) polymers. The reactor was built to be equipped with sensors and actuators for the control of reactor temperature and the mixing speed. The article discusses the circuit of the microcontroller-based platform, describes the signal conditioning steps, and evaluates the capacity of the proposed low-cost microcontroller-based interface in terms of control accuracy and system responses. It is demonstrated that the proposed microcontroller-based platform is able to operate parallel microbioreactor operation with satisfactory performances. Control accuracy at a deviation less than 5% of the set-point values and responses in the range of few seconds have been recorded. © 2015 Society for Laboratory Automation and Screening.

A Combined Adaptive Neural Network and Nonlinear Model Predictive Control for Multirate Networked Industrial Process Control.

PubMed

Wang, Tong; Gao, Huijun; Qiu, Jianbin

2016-02-01

This paper investigates the multirate networked industrial process control problem in double-layer architecture. First, the output tracking problem for sampled-data nonlinear plant at device layer with sampling period T(d) is investigated using adaptive neural network (NN) control, and it is shown that the outputs of subsystems at device layer can track the decomposed setpoints. Then, the outputs and inputs of the device layer subsystems are sampled with sampling period T(u) at operation layer to form the index prediction, which is used to predict the overall performance index at lower frequency. Radial basis function NN is utilized as the prediction function due to its approximation ability. Then, considering the dynamics of the overall closed-loop system, nonlinear model predictive control method is proposed to guarantee the system stability and compensate the network-induced delays and packet dropouts. Finally, a continuous stirred tank reactor system is given in the simulation part to demonstrate the effectiveness of the proposed method.

Analytical design of modified Smith predictor for unstable second-order processes with time delay

NASA Astrophysics Data System (ADS)

Ajmeri, Moina; Ali, Ahmad

2017-06-01

In this paper, a modified Smith predictor using three controllers, namely, stabilising (Gc), set-point tracking (Gc1), and load disturbance rejection (Gc2) controllers is proposed for second-order unstable processes with time delay. Controllers of the proposed structure are tuned using direct synthesis approach as this method enables the user to achieve a trade-off between the performance and robustness by adjusting a single design parameter. Furthermore, suitable values of the tuning parameters are recommended after studying their effect on the closed-loop performance and robustness. This is the main advantage of the proposed work over other recently published manuscripts, where authors provide only suitable ranges for the tuning parameters in spite of giving their suitable values. Simulation studies show that the proposed method results in satisfactory performance and improved robustness as compared to the recently reported control schemes. It is observed that the proposed scheme is able to work in the noisy environment also.

A Method for Exploiting Redundancy to Accommodate Actuator Limits in Multivariable Systems

NASA Technical Reports Server (NTRS)

Litt, Jonathan; Roulette, Greg

1995-01-01

This paper introduces a new method for accommodating actuator saturation in a multivariable system with actuator redundancy. Actuator saturation can cause significant deterioration in control system performance because unmet demand may result in sluggish transients and oscillations in response to setpoint changes. To help compensate for this problem, a technique has been developed which takes advantage of redundancy in multivariable systems to redistribute the unmet control demand over the remaining useful effectors. This method is not a redesign procedure, rather it modifies commands to the unlimited effectors to compensate for those which are limited, thereby exploiting the built-in redundancy. The original commands are modified by the increments due to unmet demand, but when a saturated effector comes off its limit, the incremental commands disappear and the original unmodified controller remains intact. This scheme provides a smooth transition between saturated and unsaturated modes as it divides up the unmet requirement over any available actuators. This way, if there is sufficiently redundant control authority, performance can be maintained.

[Fever of unknown origin (febris continua e causa ignota)].

PubMed

Hansen, T H; Seidenfaden-Lassen, M

1992-02-10

Fever can be recognized as a higher set-point of the normal temperature regulation which is controlled by the center in the anterior part of hypothalamus. The change in this set-point is induced by interleukin-1 (IL-1) which is the common mediator of exogenic and endogenic pyrogenic factors. IL-1 is believed to act through an induction of a prostaglandin E cascade. The normal diurnal variation in temperature can often be recognized in infectious diseases but not always in non-infectious conditions. Four different fever curves can be defined but are without differential diagnostic importance, however, septic fever curves are more likely to occur in bacteremic patients. Comparison of the most important investigations about PUO since 1960 shows that the follow-up investigations revealed a high percentage of undiagnosed cases and that the mortality due to conditions related to PUO was 6-8%. Among the other investigations, a total of 83% were diagnosed: 23% had cancer, 33% had infections, 11% had collagenic diseases, 17% had other causes and 16% were undiagnosed. To establish the diagnosis in cases of PUO, liver biopsy can be of diagnostic value especially in patients with hepatomegaly. Abdominal CT-scan, ultrasonography and Gallium 67 scintigraphy are equal in sensitivity and specificity and can supplement each other with diagnostic information. Leucocyte scintigraphy can detect local inflammatory processes. Laparotomy or laparoscopy have high diagnostic values and can be considered in patients with signs of involvement of abdominal organs if no diagnosis has been established after noninvasive investigations. Lymphography gives only limited diagnostic information in cases of PUO.

Input Shaping enhanced Active Disturbance Rejection Control for a twin rotor multi-input multi-output system (TRMS).

PubMed

Yang, Xiaoyan; Cui, Jianwei; Lao, Dazhong; Li, Donghai; Chen, Junhui

2016-05-01

In this paper, a composite control based on Active Disturbance Rejection Control (ADRC) and Input Shaping is presented for TRMS with two degrees of freedom (DOF). The control tasks consist of accurately tracking desired trajectories and obtaining disturbance rejection in both horizontal and vertical planes. Due to un-measurable states as well as uncertainties stemming from modeling uncertainty and unknown disturbance torques, ADRC is employed, and feed-forward Input Shaping is used to improve the dynamical response. In the proposed approach, because the coupling effects are maintained in controller derivation, there is no requirement to decouple the TRMS into horizontal and vertical subsystems, which is usually performed in the literature. Finally, the proposed method is implemented on the TRMS platform, and the results are compared with those of PID and ADRC in a similar structure. The experimental results demonstrate the effectiveness of the proposed method. The operation of the controller allows for an excellent set-point tracking behavior and disturbance rejection with system nonlinearity and complex coupling conditions. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Digitally controlled analog proportional-integral-derivative (PID) controller for high-speed scanning probe microscopy

NASA Astrophysics Data System (ADS)

Dukic, Maja; Todorov, Vencislav; Andany, Santiago; Nievergelt, Adrian P.; Yang, Chen; Hosseini, Nahid; Fantner, Georg E.

2017-12-01

Nearly all scanning probe microscopes (SPMs) contain a feedback controller, which is used to move the scanner in the direction of the z-axis in order to maintain a constant setpoint based on the tip-sample interaction. The most frequently used feedback controller in SPMs is the proportional-integral (PI) controller. The bandwidth of the PI controller presents one of the speed limiting factors in high-speed SPMs, where higher bandwidths enable faster scanning speeds and higher imaging resolution. Most SPM systems use digital signal processor-based PI feedback controllers, which require analog-to-digital and digital-to-analog converters. These converters introduce additional feedback delays which limit the achievable imaging speed and resolution. In this paper, we present a digitally controlled analog proportional-integral-derivative (PID) controller. The controller implementation allows tunability of the PID gains over a large amplification and frequency range, while also providing precise control of the system and reproducibility of the gain parameters. By using the analog PID controller, we were able to perform successful atomic force microscopy imaging of a standard silicon calibration grating at line rates up to several kHz.

Digitally controlled analog proportional-integral-derivative (PID) controller for high-speed scanning probe microscopy.

PubMed

Dukic, Maja; Todorov, Vencislav; Andany, Santiago; Nievergelt, Adrian P; Yang, Chen; Hosseini, Nahid; Fantner, Georg E

2017-12-01

Nearly all scanning probe microscopes (SPMs) contain a feedback controller, which is used to move the scanner in the direction of the z-axis in order to maintain a constant setpoint based on the tip-sample interaction. The most frequently used feedback controller in SPMs is the proportional-integral (PI) controller. The bandwidth of the PI controller presents one of the speed limiting factors in high-speed SPMs, where higher bandwidths enable faster scanning speeds and higher imaging resolution. Most SPM systems use digital signal processor-based PI feedback controllers, which require analog-to-digital and digital-to-analog converters. These converters introduce additional feedback delays which limit the achievable imaging speed and resolution. In this paper, we present a digitally controlled analog proportional-integral-derivative (PID) controller. The controller implementation allows tunability of the PID gains over a large amplification and frequency range, while also providing precise control of the system and reproducibility of the gain parameters. By using the analog PID controller, we were able to perform successful atomic force microscopy imaging of a standard silicon calibration grating at line rates up to several kHz.

Multicoordination Control Strategy Performance in Hybrid Power Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pezzini, Paolo; Bryden, Kenneth M.; Tucker, David

This paper evaluates a state-space methodology of a multi-input multi-output (MIMO) control strategy using a 2 × 2 tightly coupled scenario applied to a physical gas turbine fuel cell hybrid power system. A centralized MIMO controller was preferred compared to a decentralized control approach because previous simulation studies showed that the coupling effect identified during the simultaneous control of the turbine speed and cathode airflow was better minimized. The MIMO controller was developed using a state-space dynamic model of the system that was derived using first-order transfer functions empirically obtained through experimental tests. The controller performance was evaluated in termsmore » of disturbance rejection through perturbations in the gas turbine operation, and setpoint tracking maneuver through turbine speed and cathode airflow steps. The experimental results illustrate that a multicoordination control strategy was able to mitigate the coupling of each actuator to each output during the simultaneous control of the system, and improved the overall system performance during transient conditions. On the other hand, the controller showed different performance during validation in simulation environment compared to validation in the physical facility, which will require a better dynamic modeling of the system for the implementation of future multivariable control strategies.« less

Multicoordination Control Strategy Performance in Hybrid Power Systems

DOE PAGES

Pezzini, Paolo; Bryden, Kenneth M.; Tucker, David

2018-04-11

This paper evaluates a state-space methodology of a multi-input multi-output (MIMO) control strategy using a 2 × 2 tightly coupled scenario applied to a physical gas turbine fuel cell hybrid power system. A centralized MIMO controller was preferred compared to a decentralized control approach because previous simulation studies showed that the coupling effect identified during the simultaneous control of the turbine speed and cathode airflow was better minimized. The MIMO controller was developed using a state-space dynamic model of the system that was derived using first-order transfer functions empirically obtained through experimental tests. The controller performance was evaluated in termsmore » of disturbance rejection through perturbations in the gas turbine operation, and setpoint tracking maneuver through turbine speed and cathode airflow steps. The experimental results illustrate that a multicoordination control strategy was able to mitigate the coupling of each actuator to each output during the simultaneous control of the system, and improved the overall system performance during transient conditions. On the other hand, the controller showed different performance during validation in simulation environment compared to validation in the physical facility, which will require a better dynamic modeling of the system for the implementation of future multivariable control strategies.« less

A hybrid intelligent controller for a twin rotor MIMO system and its hardware implementation.

PubMed

Juang, Jih-Gau; Liu, Wen-Kai; Lin, Ren-Wei

2011-10-01

This paper presents a fuzzy PID control scheme with a real-valued genetic algorithm (RGA) to a setpoint control problem. The objective of this paper is to control a twin rotor MIMO system (TRMS) to move quickly and accurately to the desired attitudes, both the pitch angle and the azimuth angle in a cross-coupled condition. A fuzzy compensator is applied to the PID controller. The proposed control structure includes four PID controllers with independent inputs in 2-DOF. In order to reduce total error and control energy, all parameters of the controller are obtained by a RGA with the system performance index as a fitness function. The system performance index utilized the integral of time multiplied by the square error criterion (ITSE) to build a suitable fitness function in the RGA. A new method for RGA to solve more than 10 parameters in the control scheme is investigated. For real-time control, Xilinx Spartan II SP200 FPGA (Field Programmable Gate Array) is employed to construct a hardware-in-the-loop system through writing VHDL on this FPGA. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

THE EFFECTS OF CHRONIC EXERCISE CONDITIONING ON THERMOREGULATORY RESPONSE TO CHLORPYRIFOS IN FEMALE RATS.

EPA Science Inventory

Chronic exercise conditioning has been shown to alter basal thermoregulatory processes (change in thermoregulatory set-point) as well as the response to infectious fever. Chlorpyrifos (CHP), an organophosphate pesticide, causes an acute period of hypothermia followed by a delaye...

A transmission-virulence evolutionary trade-off explains attenuation of HIV-1 in Uganda

PubMed Central

Blanquart, François; Grabowski, Mary Kate; Herbeck, Joshua; Nalugoda, Fred; Serwadda, David; Eller, Michael A; Robb, Merlin L; Gray, Ronald; Kigozi, Godfrey; Laeyendecker, Oliver; Lythgoe, Katrina A; Nakigozi, Gertrude; Quinn, Thomas C; Reynolds, Steven J; Wawer, Maria J; Fraser, Christophe

2016-01-01

Evolutionary theory hypothesizes that intermediate virulence maximizes pathogen fitness as a result of a trade-off between virulence and transmission, but empirical evidence remains scarce. We bridge this gap using data from a large and long-standing HIV-1 prospective cohort, in Uganda. We use an epidemiological-evolutionary model parameterised with this data to derive evolutionary predictions based on analysis and detailed individual-based simulations. We robustly predict stabilising selection towards a low level of virulence, and rapid attenuation of the virus. Accordingly, set-point viral load, the most common measure of virulence, has declined in the last 20 years. Our model also predicts that subtype A is slowly outcompeting subtype D, with both subtypes becoming less virulent, as observed in the data. Reduction of set-point viral loads should have resulted in a 20% reduction in incidence, and a three years extension of untreated asymptomatic infection, increasing opportunities for timely treatment of infected individuals. DOI: http://dx.doi.org/10.7554/eLife.20492.001 PMID:27815945

Closed-loop control of artificial pancreatic Beta -cell in type 1 diabetes mellitus using model predictive iterative learning control.

PubMed

Wang, Youqing; Dassau, Eyal; Doyle, Francis J

2010-02-01

A novel combination of iterative learning control (ILC) and model predictive control (MPC), referred to here as model predictive iterative learning control (MPILC), is proposed for glycemic control in type 1 diabetes mellitus. MPILC exploits two key factors: frequent glucose readings made possible by continuous glucose monitoring technology; and the repetitive nature of glucose-meal-insulin dynamics with a 24-h cycle. The proposed algorithm can learn from an individual's lifestyle, allowing the control performance to be improved from day to day. After less than 10 days, the blood glucose concentrations can be kept within a range of 90-170 mg/dL. Generally, control performance under MPILC is better than that under MPC. The proposed methodology is robust to random variations in meal timings within +/-60 min or meal amounts within +/-75% of the nominal value, which validates MPILC's superior robustness compared to run-to-run control. Moreover, to further improve the algorithm's robustness, an automatic scheme for setpoint update that ensures safe convergence is proposed. Furthermore, the proposed method does not require user intervention; hence, the algorithm should be of particular interest for glycemic control in children and adolescents.

Operating boundaries of full-scale advanced water reuse treatment plants: many lessons learned from pilot plant experience.

PubMed

Bele, C; Kumar, Y; Walker, T; Poussade, Y; Zavlanos, V

2010-01-01

Three Advanced Water Treatment Plants (AWTP) have recently been built in South East Queensland as part of the Western Corridor Recycled Water Project (WCRWP) producing Purified Recycled Water from secondary treated waste water for the purpose of indirect potable reuse. At Luggage Point, a demonstration plant was primarily operated by the design team for design verification. The investigation program was then extended so that the operating team could investigate possible process optimisation, and operation flexibility. Extending the demonstration plant investigation program enabled monitoring of the long term performance of the microfiltration and reverse osmosis membranes, which did not appear to foul even after more than a year of operation. The investigation primarily identified several ways to optimise the process. It highlighted areas of risk for treated water quality, such as total nitrogen. Ample and rapid swings of salinity from 850 to 3,000 mg/l-TDS were predicted to affect the RO process day-to-day operation and monitoring. Most of the setpoints used for monitoring under HACCP were determined during the pilot plant trials.

40 CFR 1066.135 - Linearity verification.

Code of Federal Regulations, 2014 CFR

2014-07-01

... CVS, double-dilution, and partial-flow systems. (3) PM sample. (4) Chiller sample, for gaseous sampling systems that use thermal chillers to dry samples, and that use chiller temperature to calculate dewpoint at the chiller outlet. For testing, if you choose to use the high alarm temperature setpoint for...

Advanced multivariable control of a turboexpander plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altena, D.; Howard, M.; Bullin, K.

1998-12-31

This paper describes an application of advanced multivariable control on a natural gas plant and compares its performance to the previous conventional feed-back control. This control algorithm utilizes simple models from existing plant data and/or plant tests to hold the process at the desired operating point in the presence of disturbances and changes in operating conditions. The control software is able to accomplish this due to effective handling of process variable interaction, constraint avoidance and feed-forward of measured disturbances. The economic benefit of improved control lies in operating closer to the process constraints while avoiding significant violations. The South Texasmore » facility where this controller was implemented experienced reduced variability in process conditions which increased liquids recovery because the plant was able to operate much closer to the customer specified impurity constraint. An additional benefit of this implementation of multivariable control is the ability to set performance criteria beyond simple setpoints, including process variable constraints, relative variable merit and optimizing use of manipulated variables. The paper also details the control scheme applied to the complex turboexpander process and some of the safety features included to improve reliability.« less

Control and materials characterization System for 6T Superconducting Cryogen Free Magnet Facility at IUAC, New Delhi

NASA Astrophysics Data System (ADS)

Dutt, R. N.; Meena, D. K.; Kar, S.; Soni, V.; Nadaf, A.; Das, A.; Singh, F.; Datta, T. S.

2017-02-01

A system for carrying out automatic experimental measurements of various electrical transport characteristics and their relation to magnetic fields for samples mounted on the sample holder on a Variable Temperature Insert (VTI) of the Cryogen Free Superconducting Magnet System (CFMS) has been developed. The control and characterization system is capable of monitoring, online plotting and history logging in real-time of cryogenic temperatures with the Silicon (Si) Diode and Zirconium Oxy-Nitride sensors installed inside the magnet facility. Electrical transport property measurements have been automated with implementation of current reversal resistance measurements and automatic temperature set-point ramping with the parameters of interest available in real-time as well as for later analysis. The Graphical User Interface (GUI) based system is user friendly to facilitate operations. An ingenious electronics for reading Zirconium Oxy-Nitride temperature sensors has been used. Price to performance ratio has been optimized by using in house developed measurement techniques mixed with specialized commercial cryogenic measurement / control equipment.

Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System.

PubMed

Cai, Xiang; Walgenbach, Martin; Doerpmond, Malte; Schulze Lammers, Peter; Sun, Yurui

2016-01-20

To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS) by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV) was utilized for injecting chemicals, driven by a pulse-width modulation (PWM) signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID) method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input-output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy.

76 FR 40937 - Biweekly Notice; Applications and Amendments to Facility Operating Licenses Involving No...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-12

... Generator Water Level High-High'' instrument setpoint and associated allowable value. The proposed change is... [Pressurized-Water Reactor] PWR Operability Requirements and Actions for RCS Leakage Instrumentation''. Basis... monitor is the containment atmospheric gaseous radiation monitor. The monitoring of RCS leakage is not a...

Measuring School Readiness: Conceptual and Practical Considerations

ERIC Educational Resources Information Center

Snow, Kyle L.

2006-01-01

Recent interest and investment in early childhood education as a means of promoting children's school readiness has prompted the need for clear definitions of school readiness. Traditionally school readiness has been viewed within a maturationist frame, based on a chronological set-point, which led to the emergence of readiness testing. Following…

Analysis of Energy Conservation Alternatives for Standard Army Building

DTIC Science & Technology

1983-03-01

existing system because of the constant cooling and heating required. The fixed set-point with a temperature ecnomizer me, ECIP criteria in the colder... essential to completing other portions of the project. Care must, be taken to ensure that energy savings are not duplicated between projects or portions of

G T-Mohr Start-up Reactivity Insertion Transient Analysis Using Simulink

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fard, Mehdi Reisi; Blue, Thomas E.; Miller, Don W.

2006-07-01

As a part of a Department of Energy-Nuclear Engineering Research Initiative (NERI) Project, we at OSU are investigating SiC semiconductor detectors as neutron power monitors for Generation IV power reactors. As a part of this project, we are investigating the power monitoring requirements for a specific type of Generation IV reactor, namely the GT-MHR. To evaluate the power monitoring requirements for the GT-MHR that are most demanding for a SiC diode power monitor, we have developed a Simulink model to study the transient behavior of the GT-MHR. In this paper, we describe the application of the Simulink code to themore » analysis of a series of Start-up Reactivity Insertion Transients (SURITs). The SURIT is considered to be a limiting protectable accident in terms of establishing the dynamic range of a SiC power monitor because of the low count rate of the detector during the start-up and absence of the reactivity feedback mechanism at the beginning of transient. The SURIT is studied with the ultimate goal of identifying combinations of 1) reactor power scram setpoints and 2) cram initiation times (the time in which a scram must be initiated once the setpoint is exceeded) for which the GT-MHR core is protected in the event of a continuous withdrawal of a control rod bank from the core from low powers. The SURIT is initiated by withdrawing a rod bank when the reactor is cold (300 K) and sub-critical at the BOEC (Beginning of Equilibrium Cycle) condition. Various initial power levels have been considered corresponding to various degrees of sub-criticality and various source strengths. An envelope of response is determined to establish which initial powers correspond to the worst case SURIT. (authors)« less

Prevalence of seroconversion symptoms and relationship to set point viral load: Findings from a subtype C epidemic, 1995–2009

PubMed Central

Sullivan, Patrick S.; Fideli, Ulgen; Wall, Kristin M.; Chomba, Elwyn; Vwalika, Cheswa; Kilembe, William; Tichacek, Amanda; Luisi, Nicole; Mulenga, Joseph; Hunter, Eric; Boeras, Debrah; Allen, Susan

2013-01-01

Objective To describe symptoms, physical exam findings, and set point viral load associated with acute HIV seroconversion in a heterosexual cohort of discordant couples in Zambia. Design We followed HIV serodiscordant couples in Lusaka, Zambia from 1995–2009 with HIV testing of negative partners and symptom inventories 3-monthly, and physical examinations annually. Methods We compared prevalence of self-reported or treated symptoms (malaria syndrome, chronic diarrhea, asthenia, night sweats, and oral candidiasis) and annual physical exam [PE] findings (unilateral or bilateral neck, axillary, or inguinal adenopathy; and dermatosis) in seroconverting versus HIV-negative or HIV-positive intervals, controlling for repeated observations, age, and sex. A composite score comprised of significant symptoms and PE findings predictive of seroconversion versus HIV-negative intervals was constructed. We modeled the relationship between number of symptoms and PE findings at seroconversion and log set-point viral load [VL] using linear regression. Results 2,388 HIV-negative partners were followed for a median of 18 months; 429 seroconversions occurred. Neither symptoms nor PE findings were reported for most seroconverters. Seroconversion was significantly associated with malaria syndrome among non-diarrheic patients (adjusted odds ratio [aOR]=4.0) night sweats (aOR=1.4), and bilateral axillary (aOR = 1.6), inguinal (aOR=2.2), and neck (aOR=2.2) adenopathy relative to HIV-negative intervals. Median number of symptoms was positively associated with set-point VL (p<0.001). Conclusions Though most acute and early infections were asymptomatic, malaria syndrome was more common and more severe during seroconversion compared with HIV-negative and HIV-positive intervals. When present, symptoms and physical exam findings were non-specific and associated with higher set point viremia. PMID:22089380

A Comparative study between MPC and PI controller to control vacuum distillation unit for producing LVGO, MVGO, and HVGO

NASA Astrophysics Data System (ADS)

Wahid, A.; Prasetyo, A. P.

2018-03-01

This study describes the selection of controllers in the vacuum distillation unit (VDU) between a model predictive control (MPC) and a proportional-integral (PI) controller by comparing the integral square error (ISE) values. Design of VDU in this simulation is based on modified Metso Automation Inc. scheme. Controlled variables in this study are feed flow rate, feed temperature, top stage pressure, condenser level, bottom stage temperature, LVGO (light vacuum gas oil), MVGO (medium vacuum gas oil), and HVGO (heavy vacuum gas oil) flow rate. As a result, control performance improvements occurred as using MPC compared to PI controllers, when testing a set-point change, of feed flow rate control, feed temperature, top-stage pressure, bottom-stage temperature and flow rate of LVGO, MVGO, and HVGO, respectively, 36%, 6%, 92%, 53%, 90%, 96% and 88%. Only on condenser level control PI performs much better than the MPC. So PI controller is used for level condenser control. While for the test of disturbance rejection, by changing feed flow rate by 10%, there is improvement of control performance using MPC compared to PI controller on feed temperature control, top-stage pressure, bottom-stage temperature and flow rate LVGO, MVGO and HVGO 0.3%, 0.7%, 14%, 2.7%, 10.6% and 4.3%, respectively.

Internal model control for industrial wireless plant using WirelessHART hardware-in-the-loop simulator.

PubMed

Tran, Chung Duc; Ibrahim, Rosdiazli; Asirvadam, Vijanth Sagayan; Saad, Nordin; Sabo Miya, Hassan

2018-04-01

The emergence of wireless technologies such as WirelessHART and ISA100 Wireless for deployment at industrial process plants has urged the need for research and development in wireless control. This is in view of the fact that the recent application is mainly in monitoring domain due to lack of confidence in control aspect. WirelessHART has an edge over its counterpart as it is based on the successful Wired HART protocol with over 30 million devices as of 2009. Recent works on control have primarily focused on maintaining the traditional PID control structure which is proven not adequate for the wireless environment. In contrast, Internal Model Control (IMC), a promising technique for delay compensation, disturbance rejection and setpoint tracking has not been investigated in the context of WirelessHART. Therefore, this paper discusses the control design using IMC approach with a focus on wireless processes. The simulation and experimental results using real-time WirelessHART hardware-in-the-loop simulator (WH-HILS) indicate that the proposed approach is more robust to delay variation of the network than the PID. Copyright © 2017. Published by Elsevier Ltd.

A flatness-based control approach to drug infusion for cardiac function regulation

NASA Astrophysics Data System (ADS)

Rigatos, Gerasimos; Zervos, Nikolaos; Melkikh, Alexey

2016-12-01

A new control method based on differential flatness theory is developed in this article, aiming at solving the problem of regulation of haemodynamic parameters, Actually control of the cardiac output (volume of blood pumped out by heart per unit of time) and of the arterial blood pressure is achieved through the administered infusion of cardiovascular drugs, such as dopamine and sodium nitroprusside. Time delays between the control inputs and the system's outputs are taken into account. Using the principle of dynamic extension, which means that by considering certain control inputs and their derivatives as additional state variables, a state-space description for the heart's function is obtained. It is proven that the dynamic model of the heart is a differentially flat one. This enables its transformation into a linear canonical and decoupled form, for which the design of a stabilizing feedback controller becomes possible. The proposed feedback controller is of proven stability and assures fast and accurate tracking of the reference setpoints by the outputs of the heart's dynamic model. Moreover, by using a Kalman Filter-based disturbances' estimator, it becomes possible to estimate in real-time and compensate for the model uncertainty and external perturbation inputs that affect the heart's model.

Control strategies for nitrous oxide emissions reduction on wastewater treatment plants operation.

PubMed

Santín, I; Barbu, M; Pedret, C; Vilanova, R

2017-11-15

The present paper focused on reducing greenhouse gases emissions in wastewater treatment plants operation by application of suitable control strategies. Specifically, the objective is to reduce nitrous oxide emissions during the nitrification process. Incomplete nitrification in the aerobic tanks can lead to an accumulation of nitrite that triggers the nitrous oxide emissions. In order to avoid the peaks of nitrous oxide emissions, this paper proposes a cascade control configuration by manipulating the dissolved oxygen set-points in the aerobic tanks. This control strategy is combined with ammonia cascade control already applied in the literature. This is performed with the objective to take also into account effluent pollutants and operational costs. In addition, other greenhouse gases emissions sources are also evaluated. Results have been obtained by simulation, using a modified version of Benchmark Simulation Model no. 2, which takes into account greenhouse gases emissions. This is called Benchmark Simulation Model no. 2 Gas. The results show that the proposed control strategies are able to reduce by 29.86% of nitrous oxide emissions compared to the default control strategy, while maintaining a satisfactory trade-off between water quality and costs. Copyright © 2017 Elsevier Ltd. All rights reserved.

ATLAS LTCS Vertically Challenged System Lessons Learned

NASA Technical Reports Server (NTRS)

Patel, Deepak; Garrison, Matt; Ku, Jentung

2014-01-01

Re-planning of LTCS TVAC testing and supporting RTA (Receiver Telescope Assembly) Test Plan and Procedure document preparation. The Laser Thermal Control System (LTCS) is designed to maintain the lasers onboard Advanced Topographic Laser Altimeter System (ATLAS) at their operational temperatures. In order to verify the functionality of the LTCS, a thermal balance test of the thermal hardware was performed. During the first cold start of the LTCS, the Loop Heat Pipe (LHP) was unable to control the laser mass simulators temperature. The control heaters were fully on and the loop temperature remained well below the desired setpoint. Thermal analysis of the loop did not show these results. This unpredicted behavior of the LTCS was brought up to a panel of LHP experts. Based on the testing and a review of all the data, there were multiple diagnostic performed in order to narrow down the cause. The prevailing theory is that gravity is causing oscillating flow within the loop, which artificially increased the control power needs. This resulted in a replan of the LTCS test flow and the addition of a GSE heater to allow vertical operation.

Design of neural network model-based controller in a fed-batch microbial electrolysis cell reactor for bio-hydrogen gas production

NASA Astrophysics Data System (ADS)

Azwar; Hussain, M. A.; Abdul-Wahab, A. K.; Zanil, M. F.; Mukhlishien

2018-03-01

One of major challenge in bio-hydrogen production process by using MEC process is nonlinear and highly complex system. This is mainly due to the presence of microbial interactions and highly complex phenomena in the system. Its complexity makes MEC system difficult to operate and control under optimal conditions. Thus, precise control is required for the MEC reactor, so that the amount of current required to produce hydrogen gas can be controlled according to the composition of the substrate in the reactor. In this work, two schemes for controlling the current and voltage of MEC were evaluated. The controllers evaluated are PID and Inverse neural network (NN) controller. The comparative study has been carried out under optimal condition for the production of bio-hydrogen gas wherein the controller output is based on the correlation of optimal current and voltage to the MEC. Various simulation tests involving multiple set-point changes and disturbances rejection have been evaluated and the performances of both controllers are discussed. The neural network-based controller results in fast response time and less overshoots while the offset effects are minimal. In conclusion, the Inverse neural network (NN)-based controllers provide better control performance for the MEC system compared to the PID controller.

The Effects of Prior Knowledge Activation on Free Recall and Study Time Allocation.

ERIC Educational Resources Information Center

Machiels-Bongaerts, Maureen; And Others

The effects of mobilizing prior knowledge on information processing were studied. Two hypotheses, the cognitive set-point hypothesis and the selective attention hypothesis, try to account for the facilitation effects of prior knowledge activation. These hypotheses predict different recall patterns as a result of mobilizing prior knowledge. In…

Center for the Built Environment: UFAD Cooling Load Design Tool

Science.gov Websites

Energy Publications Project Title: Underfloor Air Distribution (UFAD) Cooling Load Design Tool Providing . Webster, 2010. Development of a simplified cooling load design tool for underfloor air distribution Near-ZNE Buildings Setpoint Energy Savings Calculator UFAD Case Studies UFAD Cooling Design Tool UFAD

Center for the Built Environment: Research on Building HVAC Systems

Science.gov Websites

, and lessons learned. Underfloor Air Distribution (UFAD) Cooling Airflow Design Tool Developing simplified design tools for optimization of underfloor systems. Underfloor Air Distribution (UFAD) Cost Near-ZNE Buildings Setpoint Energy Savings Calculator UFAD Case Studies UFAD Cooling Design Tool UFAD

75 FR 81667 - Biweekly Notice; Applications and Amendments to Facility Operating Licenses Involving No...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-28

...-Filing system does not support unlisted software, and the NRC Meta System Help Desk will not be able to... Setpoint Methodology for LSSS [Limiting Safety System Setting] Functions,'' which included the instrument... System Instrumentation,'' Function 3, Condensate Storage Tank Level--Low. The supporting TS Bases will...

78 FR 38078 - Biweekly Notice; Applications and Amendments to Facility Operating Licenses and Combined Licenses...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-25

... SFP Purification Loop and recirculation and purification of the RWST water using the BARS is not... revise the minimum volume and low level setpoint on the Refueling Water Storage Tank. Because the... proposed change would revise Technical Specification 3.5.4, ``Refueling Water Storage Tank (RWST)'' such...

Life Goals Matter to Happiness: A Revision of Set-Point Theory

ERIC Educational Resources Information Center

Headey, Bruce

2008-01-01

Using data from the long-running German Socio-Economic Panel Survey (SOEP), this paper provides evidence that life goals matter substantially to subjective well-being (SWB). Non-zero sum goals, which include commitment to family, friends and social and political involvement, promote life satisfaction. Zero sum goals, including commitment to career…

A CPS Based Optimal Operational Control System for Fused Magnesium Furnace

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chai, Tian-you; Wu, Zhi-wei; Wang, Hong

Fused magnesia smelting for fused magnesium furnace (FMF) is an energy intensive process with high temperature and comprehensive complexities. Its operational index namely energy consumption per ton (ECPT) is defined as the consumed electrical energy per ton of acceptable quality and is difficult to measure online. Moreover, the dynamics of ECPT cannot be precisely modelled mathematically. The model parameters of the three-phase currents of the electrodes such as the molten pool level, its variation rate and resistance are uncertain and nonlinear functions of the changes in both the smelting process and the raw materials composition. In this paper, an integratedmore » optimal operational control algorithm proposed is composed of a current set-point control, a current switching control and a self-optimized tuning mechanism. The tight conjoining of and coordination between the computational resources including the integrated optimal operational control, embedded software, industrial cloud, wireless communication and the physical resources of FMF constitutes a cyber-physical system (CPS) based embedded optimal operational control system. Successful application of this system has been made for a production line with ten fused magnesium furnaces in a factory in China, leading to a significant reduced ECPT.« less

Algorithms for a Closed-Loop Artificial Pancreas: The Case for Model Predictive Control

PubMed Central

Bequette, B. Wayne

2013-01-01

The relative merits of model predictive control (MPC) and proportional-integral-derivative (PID) control are discussed, with the end goal of a closed-loop artificial pancreas (AP). It is stressed that neither MPC nor PID are single algorithms, but rather are approaches or strategies that may be implemented very differently by different engineers. The primary advantages to MPC are that (i) constraints on the insulin delivery rate (and/or insulin on board) can be explicitly included in the control calculation; (ii) it is a general framework that makes it relatively easy to include the effect of meals, exercise, and other events that are a function of the time of day; and (iii) it is flexible enough to include many different objectives, from set-point tracking (target) to zone (control to range). In the end, however, it is recognized that the control algorithm, while important, represents only a portion of the effort required to develop a closed-loop AP. Thus, any number of algorithms/approaches can be successful—the engineers involved in the design must have experience with the particular technique, including the important experience of implementing the algorithm in human studies and not simply through simulation studies. PMID:24351190

Actuator stiction compensation via variable amplitude pulses.

PubMed

Arifin, B M S; Munaro, C J; Angarita, O F B; Cypriano, M V G; Shah, S L

2018-02-01

A novel model free stiction compensation scheme is developed which eliminates the oscillations and also reduces valve movement, allowing good setpoint tracking and disturbance rejection. Pulses with varying amplitude are added to the controller output to overcome stiction and when the error becomes smaller than a specified limit, the compensation ceases and remains in a standby mode. The compensation re-starts as soon as the error exceeds the user specified threshold. The ability to cope with uncertainty in friction is a feature achieved by the use of pulses of varying amplitude. The algorithm has been evaluated via simulation and by application on an industrial DCS system interfaced to a pilot scale process with features identical to those found in industry including a valve positioner. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Optimal supplementary frequency controller design using the wind farm frequency model and controller parameters stability region.

PubMed

Toulabi, Mohammadreza; Bahrami, Shahab; Ranjbar, Ali Mohammad

2018-03-01

In most of the existing studies, the frequency response in the variable speed wind turbines (VSWTs) is simply realized by changing the torque set-point via appropriate inputs such as frequency deviations signal. However, effective dynamics and systematic process design have not been comprehensively discussed yet. Accordingly, this paper proposes a proportional-derivative frequency controller and investigates its performance in a wind farm consisting of several VSWTs. A band-pass filter is deployed before the proposed controller to avoid responding to either steady state frequency deviations or high rate of change of frequency. To design the controller, the frequency model of the wind farm is first characterized. The proposed controller is then designed based on the obtained open loop system. The stability region associated with the controller parameters is analytically determined by decomposing the closed-loop system's characteristic polynomial into the odd and even parts. The performance of the proposed controller is evaluated through extensive simulations in MATLAB/Simulink environment in a power system comprising a high penetration of VSWTs equipped with the proposed controller. Finally, based on the obtained feasible area and appropriate objective function, the optimal values associated with the controller parameters are determined using the genetic algorithm (GA). Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Definition and dynamic control of a continuous chromatography process independent of cell culture titer and impurities.

PubMed

Chmielowski, Rebecca A; Mathiasson, Linda; Blom, Hans; Go, Daniel; Ehring, Hanno; Khan, Heera; Li, Hong; Cutler, Collette; Lacki, Karol; Tugcu, Nihal; Roush, David

2017-12-01

Advances in cell culture technology have enabled the production of antibody titers upwards of 30g/L. These highly productive cell culture systems can potentially lead to productivity bottlenecks in downstream purification due to lower column loadings, especially in the primary capture chromatography step. Alternative chromatography solutions to help remedy this bottleneck include the utilization of continuous processing systems such as periodic counter-current chromatography (PCC). Recent studies have provided methods to optimize and improve the design of PCC for cell culture titers up to about 3g/L. This paper defines a continuous loading strategy for PCC that is independent of cell culture background and encompasses cell culture titers up to about 31g/L. Initial experimentation showed a challenge with determining a difference in change in UV280nm signal (ie. ΔUV) between cell culture feed and monoclonal antibody (mAb) concentration. Further investigation revealed UV280nm absorbance of the cell culture feedstock without antibody was outside of the linear range of detection for a given cell pathlength. Additional experimentation showed the difference in ΔUV for various cell culture feeds can be either theoretically predicted by Beer's Law given a known absorbance of the media background and impurities or experimentally determined using various UV280nm cell pathlengths. Based on these results, a 0.35mm pathlength at UV280nm was chosen for dynamic control to overcome the background signal. The pore diffusion model showed good agreement with the experimental frontal analysis data, which resulted in definition of a ΔUV setpoint range between 20 and 70% for 3C-PCC experiments. Product quality of the elution pools was acceptable between various cell culture feeds and titers up to about 41g/L. Results indicated the following ΔUV setpoints to achieve robust dynamic control and maintain 3C-PCC yield: ∼20-45% for titers greater than 10g/L depending on UV absorbance of the HCCF and ∼45-70% for titers of up to 10g/L independent of UV absorbance of the HCCF. The strategy and results presented in this paper show column loading in a continuous chromatography step can be dynamically controlled independent of the cell culture feedstock and titer, and allow for enhanced process control built into the downstream continuous operations. Copyright © 2017 Elsevier B.V. All rights reserved.

Genomic Programming of Human Neonatal Dendritic Cells in Congenital Systemic and In Vitro Cytomegalovirus Infection Reveal Plastic and Robust Immune Pathway Biology Responses

PubMed Central

Dantoft, Widad; Martínez-Vicente, Pablo; Jafali, James; Pérez-Martínez, Lara; Martin, Kim; Kotzamanis, Konstantinos; Craigon, Marie; Auer, Manfred; Young, Neil T.; Walsh, Paul; Marchant, Arnaud; Angulo, Ana; Forster, Thorsten; Ghazal, Peter

2017-01-01

Neonates and especially premature infants are highly susceptible to infection but still can have a remarkable resilience that is poorly understood. The view that neonates have an incomplete or deficient immune system is changing. Human neonatal studies are challenging, and elucidating host protective responses and underlying cognate pathway biology, in the context of viral infection in early life, remains to be fully explored. In both resource rich and poor settings, human cytomegalovirus (HCMV) is the most common cause of congenital infection. By using unbiased systems analyses of transcriptomic resources for HCMV neonatal infection, we find the systemic response of a preterm congenital HCMV infection, involves a focused IFN regulatory response associated with dendritic cells. Further analysis of transcriptional-programming of neonatal dendritic cells in response to HCMV infection in culture revealed an early dominant IFN-chemokine regulatory subnetworks, and at later times the plasticity of pathways implicated in cell-cycle control and lipid metabolism. Further, we identify previously unknown suppressed networks associated with infection, including a select group of GPCRs. Functional siRNA viral growth screen targeting 516-GPCRs and subsequent validation identified novel GPCR-dependent antiviral (ADORA1) and proviral (GPR146, RGS16, PTAFR, SCTR, GPR84, GPR85, NMUR2, FZ10, RDS, CCL17, and SORT1) roles. By contrast a gene family cluster of protocadherins is significantly differentially induced in neonatal cells, suggestive of possible immunomodulatory roles. Unexpectedly, programming responses of adult and neonatal dendritic cells, upon HCMV infection, demonstrated comparable quantitative and qualitative responses showing that functionally, neonatal dendritic cell are not overly compromised. However, a delay in responses of neonatal cells for IFN subnetworks in comparison with adult-derived cells are notable, suggestive of subtle plasticity differences. These findings support a set-point control mechanism rather than immaturity for explaining not only neonatal susceptibility but also resilience to infection. In summary, our findings show that neonatal HCMV infection leads to a highly plastic and functional robust programming of dendritic cells in vivo and in vitro. In comparison with adults, a minimal number of subtle quantitative and temporal differences may contribute to variability in host susceptibility and resilience, in a context dependent manner. PMID:28993767

Genomic Programming of Human Neonatal Dendritic Cells in Congenital Systemic and In Vitro Cytomegalovirus Infection Reveal Plastic and Robust Immune Pathway Biology Responses.

PubMed

Dantoft, Widad; Martínez-Vicente, Pablo; Jafali, James; Pérez-Martínez, Lara; Martin, Kim; Kotzamanis, Konstantinos; Craigon, Marie; Auer, Manfred; Young, Neil T; Walsh, Paul; Marchant, Arnaud; Angulo, Ana; Forster, Thorsten; Ghazal, Peter

2017-01-01

Neonates and especially premature infants are highly susceptible to infection but still can have a remarkable resilience that is poorly understood. The view that neonates have an incomplete or deficient immune system is changing. Human neonatal studies are challenging, and elucidating host protective responses and underlying cognate pathway biology, in the context of viral infection in early life, remains to be fully explored. In both resource rich and poor settings, human cytomegalovirus (HCMV) is the most common cause of congenital infection. By using unbiased systems analyses of transcriptomic resources for HCMV neonatal infection, we find the systemic response of a preterm congenital HCMV infection, involves a focused IFN regulatory response associated with dendritic cells. Further analysis of transcriptional-programming of neonatal dendritic cells in response to HCMV infection in culture revealed an early dominant IFN-chemokine regulatory subnetworks, and at later times the plasticity of pathways implicated in cell-cycle control and lipid metabolism. Further, we identify previously unknown suppressed networks associated with infection, including a select group of GPCRs. Functional siRNA viral growth screen targeting 516-GPCRs and subsequent validation identified novel GPCR-dependent antiviral (ADORA1) and proviral (GPR146, RGS16, PTAFR, SCTR, GPR84, GPR85, NMUR2, FZ10, RDS, CCL17, and SORT1) roles. By contrast a gene family cluster of protocadherins is significantly differentially induced in neonatal cells, suggestive of possible immunomodulatory roles. Unexpectedly, programming responses of adult and neonatal dendritic cells, upon HCMV infection, demonstrated comparable quantitative and qualitative responses showing that functionally, neonatal dendritic cell are not overly compromised. However, a delay in responses of neonatal cells for IFN subnetworks in comparison with adult-derived cells are notable, suggestive of subtle plasticity differences. These findings support a set-point control mechanism rather than immaturity for explaining not only neonatal susceptibility but also resilience to infection. In summary, our findings show that neonatal HCMV infection leads to a highly plastic and functional robust programming of dendritic cells in vivo and in vitro . In comparison with adults, a minimal number of subtle quantitative and temporal differences may contribute to variability in host susceptibility and resilience, in a context dependent manner.

Proportional and Integral Thermal Control System for Large Scale Heating Tests

NASA Technical Reports Server (NTRS)

Fleischer, Van Tran

2015-01-01

The National Aeronautics and Space Administration Armstrong Flight Research Center (Edwards, California) Flight Loads Laboratory is a unique national laboratory that supports thermal, mechanical, thermal/mechanical, and structural dynamics research and testing. A Proportional Integral thermal control system was designed and implemented to support thermal tests. A thermal control algorithm supporting a quartz lamp heater was developed based on the Proportional Integral control concept and a linearized heating process. The thermal control equations were derived and expressed in terms of power levels, integral gain, proportional gain, and differences between thermal setpoints and skin temperatures. Besides the derived equations, user's predefined thermal test information generated in the form of thermal maps was used to implement the thermal control system capabilities. Graphite heater closed-loop thermal control and graphite heater open-loop power level were added later to fulfill the demand for higher temperature tests. Verification and validation tests were performed to ensure that the thermal control system requirements were achieved. This thermal control system has successfully supported many milestone thermal and thermal/mechanical tests for almost a decade with temperatures ranging from 50 F to 3000 F and temperature rise rates from -10 F/s to 70 F/s for a variety of test articles having unique thermal profiles and test setups.

On the Application of Different Event-Based Sampling Strategies to the Control of a Simple Industrial Process

PubMed Central

Sánchez, José; Guarnes, Miguel Ángel; Dormido, Sebastián

2009-01-01

This paper is an experimental study of the utilization of different event-based strategies for the automatic control of a simple but very representative industrial process: the level control of a tank. In an event-based control approach it is the triggering of a specific event, and not the time, that instructs the sensor to send the current state of the process to the controller, and the controller to compute a new control action and send it to the actuator. In the document, five control strategies based on different event-based sampling techniques are described, compared, and contrasted with a classical time-based control approach and a hybrid one. The common denominator in the time, the hybrid, and the event-based control approaches is the controller: a proportional-integral algorithm with adaptations depending on the selected control approach. To compare and contrast each one of the hybrid and the pure event-based control algorithms with the time-based counterpart, the two tasks that a control strategy must achieve (set-point following and disturbance rejection) are independently analyzed. The experimental study provides new proof concerning the ability of event-based control strategies to minimize the data exchange among the control agents (sensors, controllers, actuators) when an error-free control of the process is not a hard requirement. PMID:22399975

Model Based Predictive Control of Multivariable Hammerstein Processes with Fuzzy Logic Hypercube Interpolated Models

PubMed Central

Coelho, Antonio Augusto Rodrigues

2016-01-01

This paper introduces the Fuzzy Logic Hypercube Interpolator (FLHI) and demonstrates applications in control of multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) processes with Hammerstein nonlinearities. FLHI consists of a Takagi-Sugeno fuzzy inference system where membership functions act as kernel functions of an interpolator. Conjunction of membership functions in an unitary hypercube space enables multivariable interpolation of N-dimensions. Membership functions act as interpolation kernels, such that choice of membership functions determines interpolation characteristics, allowing FLHI to behave as a nearest-neighbor, linear, cubic, spline or Lanczos interpolator, to name a few. The proposed interpolator is presented as a solution to the modeling problem of static nonlinearities since it is capable of modeling both a function and its inverse function. Three study cases from literature are presented, a single-input single-output (SISO) system, a MISO and a MIMO system. Good results are obtained regarding performance metrics such as set-point tracking, control variation and robustness. Results demonstrate applicability of the proposed method in modeling Hammerstein nonlinearities and their inverse functions for implementation of an output compensator with Model Based Predictive Control (MBPC), in particular Dynamic Matrix Control (DMC). PMID:27657723

Enhancing dissolved oxygen control using an on-line hybrid fuzzy-neural soft-sensing model-based control system in an anaerobic/anoxic/oxic process.

PubMed

Huang, Mingzhi; Wan, Jinquan; Hu, Kang; Ma, Yongwen; Wang, Yan

2013-12-01

An on-line hybrid fuzzy-neural soft-sensing model-based control system was developed to optimize dissolved oxygen concentration in a bench-scale anaerobic/anoxic/oxic (A(2)/O) process. In order to improve the performance of the control system, a self-adapted fuzzy c-means clustering algorithm and adaptive network-based fuzzy inference system (ANFIS) models were employed. The proposed control system permits the on-line implementation of every operating strategy of the experimental system. A set of experiments involving variable hydraulic retention time (HRT), influent pH (pH), dissolved oxygen in the aerobic reactor (DO), and mixed-liquid return ratio (r) was carried out. Using the proposed system, the amount of COD in the effluent stabilized at the set-point and below. The improvement was achieved with optimum dissolved oxygen concentration because the performance of the treatment process was optimized using operating rules implemented in real time. The system allows various expert operational approaches to be deployed with the goal of minimizing organic substances in the outlet while using the minimum amount of energy.

Enhanced IMC design of load disturbance rejection for integrating and unstable processes with slow dynamics.

PubMed

Liu, Tao; Gao, Furong

2011-04-01

In view of the deficiencies in existing internal model control (IMC)-based methods for load disturbance rejection for integrating and unstable processes with slow dynamics, a modified IMC-based controller design is proposed to deal with step- or ramp-type load disturbance that is often encountered in engineering practices. By classifying the ways through which such load disturbance enters into the process, analytical controller formulae are correspondingly developed, based on a two-degree-of-freedom (2DOF) control structure that allows for separate optimization of load disturbance rejection from setpoint tracking. An obvious merit is that there is only a single adjustable parameter in the proposed controller, which in essence corresponds to the time constant of the closed-loop transfer function for load disturbance rejection, and can be monotonically tuned to meet a good trade-off between disturbance rejection performance and closed-loop robust stability. At the same time, robust tuning constraints are given to accommodate process uncertainties in practice. Illustrative examples from the recent literature are used to show effectiveness and merits of the proposed method for different cases of load disturbance. Copyright © 2010. Published by Elsevier Ltd.

Increased Coal Plant Flexibility Can Improve Renewables Integration |

Science.gov Websites

practices that enable lower turndowns, faster starts and stops, and faster ramping between load set-points faster ramp rates and faster and less expensive starts. Flexible Load - Demand Response Resources Demand response (DR) is a load management practice of deliberately reducing or adding load to balance the system

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2013 CFR

2013-01-01

... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of pool...

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2012 CFR

2012-01-01

... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of pool...

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2011 CFR

2011-01-01

... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of pool...

10 CFR 36.59 - Detection of leaking sources.

Code of Federal Regulations, 2014 CFR

2014-01-01

... alarm set-point to a higher level if necessary to operate the pool water purification system to clean up... certificate from a transferor that leak test has been done within the 6 months before the transfer. Water from... either by using a radiation monitor on a pool water circulating system or by analysis of a sample of pool...

Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System

PubMed Central

Cai, Xiang; Walgenbach, Martin; Doerpmond, Malte; Schulze Lammers, Peter; Sun, Yurui

2016-01-01

To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS) by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV) was utilized for injecting chemicals, driven by a pulse-width modulation (PWM) signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID) method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input–output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy. PMID:26805833

Modelica buildings library

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wetter, Michael; Zuo, Wangda; Nouidui, Thierry S.

This paper describes the Buildings library, a free open-source library that is implemented in Modelica, an equation-based object-oriented modeling language. The library supports rapid prototyping, as well as design and operation of building energy and control systems. First, we describe the scope of the library, which covers HVAC systems, multi-zone heat transfer and multi-zone airflow and contaminant transport. Next, we describe differentiability requirements and address how we implemented them. We describe the class hierarchy that allows implementing component models by extending partial implementations of base models of heat and mass exchangers, and by instantiating basic models for conservation equations andmore » flow resistances. We also describe associated tools for pre- and post-processing, regression tests, co-simulation and real-time data exchange with building automation systems. Furthermore, the paper closes with an example of a chilled water plant, with and without water-side economizer, in which we analyzed the system-level efficiency for different control setpoints.« less

A versatile small form factor twisted-pair TFC FMC for MTCA AMCs

NASA Astrophysics Data System (ADS)

Meder, L.; Lebedev, J.; Becker, J.

2017-03-01

In continuous readout systems of particle physics experiments, the provision of a common clock and time reference and the distribution of critical low latency messages to the processing and fronted layers of the readout are crucial tasks. In the context of the Compressed Baryonic Matter (CBM) experiment, a versatile small form factor Timing and Fast-Control (TFC) interfacing FPGA Mezzanine Card (FMC) was developed, offering bidirectional twisted-pair (TP) links for the communication between TFC nodes. Also a versatile clocking including voltage controlled oscillators and a connection to the telecommunication clock lines of mTCA crates are available. Being designed for both TFC Master and Slaves, the card allows rapid system developments without additional Slave hardware circuits. Measurements show that it is possible to transmit over cable lengths of 25 m at a rate of 240 Mbit/s for all data channels simultaneously. A TFC Master-Slave system using two of these cards can be synchronized with a precision of ±10 ps to an user-defined phase setpoint.

Modelica buildings library

DOE PAGES

Wetter, Michael; Zuo, Wangda; Nouidui, Thierry S.; ...

2013-03-13

This paper describes the Buildings library, a free open-source library that is implemented in Modelica, an equation-based object-oriented modeling language. The library supports rapid prototyping, as well as design and operation of building energy and control systems. First, we describe the scope of the library, which covers HVAC systems, multi-zone heat transfer and multi-zone airflow and contaminant transport. Next, we describe differentiability requirements and address how we implemented them. We describe the class hierarchy that allows implementing component models by extending partial implementations of base models of heat and mass exchangers, and by instantiating basic models for conservation equations andmore » flow resistances. We also describe associated tools for pre- and post-processing, regression tests, co-simulation and real-time data exchange with building automation systems. Furthermore, the paper closes with an example of a chilled water plant, with and without water-side economizer, in which we analyzed the system-level efficiency for different control setpoints.« less

Opportunities and constraints of presently used thermal manikins for thermo-physiological simulation of the human body.

PubMed

Psikuta, Agnes; Kuklane, Kalev; Bogdan, Anna; Havenith, George; Annaheim, Simon; Rossi, René M

2016-03-01

Combining the strengths of an advanced mathematical model of human physiology and a thermal manikin is a new paradigm for simulating thermal behaviour of humans. However, the forerunners of such adaptive manikins showed some substantial limitations. This project aimed to determine the opportunities and constraints of the existing thermal manikins when dynamically controlled by a mathematical model of human thermal physiology. Four thermal manikins were selected and evaluated for their heat flux measurement uncertainty including lateral heat flows between manikin body parts and the response of each sector to the frequent change of the set-point temperature typical when using a physiological model for control. In general, all evaluated manikins are suitable for coupling with a physiological model with some recommendations for further improvement of manikin dynamic performance. The proposed methodology is useful to improve the performance of the adaptive manikins and help to provide a reliable and versatile tool for the broad research and development domain of clothing, automotive and building engineering.

A new modelling and identification scheme for time-delay systems with experimental investigation: a relay feedback approach

NASA Astrophysics Data System (ADS)

Pandey, Saurabh; Majhi, Somanath; Ghorai, Prasenjit

2017-07-01

In this paper, the conventional relay feedback test has been modified for modelling and identification of a class of real-time dynamical systems in terms of linear transfer function models with time-delay. An ideal relay and unknown systems are connected through a negative feedback loop to bring the sustained oscillatory output around the non-zero setpoint. Thereafter, the obtained limit cycle information is substituted in the derived mathematical equations for accurate identification of unknown plants in terms of overdamped, underdamped, critically damped second-order plus dead time and stable first-order plus dead time transfer function models. Typical examples from the literature are included for the validation of the proposed identification scheme through computer simulations. Subsequently, the comparisons between estimated model and true system are drawn through integral absolute error criterion and frequency response plots. Finally, the obtained output responses through simulations are verified experimentally on real-time liquid level control system using Yokogawa Distributed Control System CENTUM CS3000 set up.

A linear quadratic Gaussian with loop transfer recovery proximity operations autopilot for spacecraft. M.S. Thesis - MIT

NASA Technical Reports Server (NTRS)

Chen, George T.

1987-01-01

An automatic control scheme for spacecraft proximity operations is presented. The controller is capable of holding the vehicle at a prescribed location relative to a target, or maneuvering it to a different relative position using straight line-of-sight translations. The autopilot uses a feedforward loop to initiate and terminate maneuvers, and for operations at nonequilibrium set-points. A multivariate feedback loop facilitates precise position and velocity control in the presence of sensor noise. The feedback loop is formulated using the Linear Quadratic Gaussian (LQG) with Loop Transfer Recovery (LTR) design procedure. Linear models of spacecraft dynamics, adapted from Clohessey-Wiltshire Equations, are augmented and loop shaping techniques are applied to design a target feedback loop. The loop transfer recovery procedure is used to recover the frequency domain properties of the target feedback loop. The resulting compensator is integrated into an autopilot which is tested in a high fidelity Space Shuttle Simulator. The autopilot performance is evaluated for a variety of proximity operations tasks envisioned for future Shuttle flights.

The concept of "buffering" in systems and control theory: from metaphor to math.

PubMed

Schmitt, Bernhard M

2004-10-04

The paradigm of "buffering" is used increasingly for the description of diverse "systemic" phenomena encountered in evolutionary genetics, ecology, integrative physiology, and other areas. However, in this new context, the paradigm has not yet matured into a truly quantitative concept inasmuch as it lacks a corresponding quantitative measure of "systems-level buffering strength". Here, I develop such measures on the basis of a formal and general approach to the quantitation of buffering action. "Systems-level buffering" is shown to be synonymous with "disturbance rejection" in feedback-control systems, and can be quantitated by means of dimensionless proportions between partial flows in two-partitioned systems. The units allow either the time-independent, "static" buffering properties or the time-dependent, "dynamic" ones to be measured. Analogous to this "resistance to change", one can define and measure the "conductance to change"; this quantity corresponds to "set-point tracking" in feedback-control systems. Together, these units provide a systematic framework for the quantitation of buffering action in systems biology, and reveal the common principle behind systems-level buffering, classical acid-base buffering, and multiple other manifestations of buffering.

Human location estimation using thermopile array sensor

NASA Astrophysics Data System (ADS)

Parnin, S.; Rahman, M. M.

2017-11-01

Utilization of Thermopile sensor at an early stage of human detection is challenging as there are many things that produce thermal heat other than human such as electrical appliances and animals. Therefrom, an algorithm for early presence detection has been developed through the study of human body temperature behaviour with respect to the room temperature. The change in non-contact detected temperature of human varied according to body parts. In an indoor room, upper parts of human body change up to 3°C whereas lower part ranging from 0.58°C to 1.71°C. The average changes in temperature of human is used as a conditional set-point value in the program algorithm to detect human presence. The current position of human and its respective angle is gained when human is presence at certain pixels of Thermopile’s sensor array. Human position is estimated successfully as the developed sensory system is tested to the actuator of a stand fan.

Controlling the nitrite:ammonium ratio in a SHARON reactor in view of its coupling with an Anammox process.

PubMed

Volcke, E I P; van Loosdrecht, M C M; Vanrolleghem, P A

2006-01-01

The combined SHARON-Anammox process for treating wastewater streams with high ammonia load is the focus of this paper. In particular, partial nitritation in the SHARON reactor should be performed to such an extent that a nitrite:ammonium ratio is generated which is optimal for full conversion in an Anammox process. In the simulation studies performed in this contribution, the nitrite:ammonium ratio produced in a SHARON process with fixed volume, as well as its effect on the subsequent Anammox process, is examined for realistic influent conditions and considering both direct and indirect pH effects on the SHARON process. Several possible operating modes for the SHARON reactor, differing in control strategies for O2, pH and the produced nitrite:ammonium ratio and based on regulating the air flow rate and/or acid/base addition, are systematically evaluated. The results are quantified through an operating cost index. Best results are obtained by means of cascade feedback control of the SHARON effluent nitrite:ammonium ratio through setting an O2 set-point that is tracked by adjusting the air flow rate, combined with single loop pH control through acid/base addition.

Bypass apparatus and method for series connected energy storage devices

DOEpatents

Rouillard, Jean; Comte, Christophe; Daigle, Dominik

2000-01-01

A bypass apparatus and method for series connected energy storage devices. Each of the energy storage devices coupled to a common series connection has an associated bypass unit connected thereto in parallel. A current bypass unit includes a sensor which is coupled in parallel with an associated energy storage device or cell and senses an energy parameter indicative of an energy state of the cell, such as cell voltage. A bypass switch is coupled in parallel with the energy storage cell and operable between a non-activated state and an activated state. The bypass switch, when in the non-activated state, is substantially non-conductive with respect to current passing through the energy storage cell and, when in the activated state, provides a bypass current path for passing current to the series connection so as to bypass the associated cell. A controller controls activation of the bypass switch in response to the voltage of the cell deviating from a pre-established voltage setpoint. The controller may be included within the bypass unit or be disposed on a control platform external to the bypass unit. The bypass switch may, when activated, establish a permanent or a temporary bypass current path.

Explaining happiness

PubMed Central

Easterlin, Richard A.

2003-01-01

What do social survey data tell us about the determinants of happiness? First, that the psychologists' setpoint model is questionable. Life events in the nonpecuniary domain, such as marriage, divorce, and serious disability, have a lasting effect on happiness, and do not simply deflect the average person temporarily above or below a setpoint given by genetics and personality. Second, mainstream economists' inference that in the pecuniary domain “more is better,” based on revealed preference theory, is problematic. An increase in income, and thus in the goods at one's disposal, does not bring with it a lasting increase in happiness because of the negative effect on utility of hedonic adaptation and social comparison. A better theory of happiness builds on the evidence that adaptation and social comparison affect utility less in the nonpecuniary than pecuniary domains. Because individuals fail to anticipate the extent to which adaptation and social comparison undermine expected utility in the pecuniary domain, they allocate an excessive amount of time to pecuniary goals, and shortchange nonpecuniary ends such as family life and health, reducing their happiness. There is need to devise policies that will yield better-informed individual preferences, and thereby increase individual and societal well-being. PMID:12958207

Pinning effects from substrate and AFM tip surfaces on interfacial nanobubbles

NASA Astrophysics Data System (ADS)

Teshima, Hideaki; Takahashi, Koji; Takata, Yasuyuki; Nishiyama, Takashi

2017-11-01

Measurement accuracy of atomic force microscopy (AFM) is vital to understand the mechanism of interfacial nanobubbles. In this study, we report the influence of pinning derived from both substrate and AFM tip surfaces on the measured shape of interfacial nanobubbles in peak force tapping mode. First, we pushed the nanobubbles using the AFM tip with high peak force setpoint. As a result, the deformed nanobubbles kept their flat shape for several tens of minutes. We quantitatively discuss the pinning force from substrate surface, which retains the flat shape enhancing the stability of nanobubbles. Next, we prepared three AFM tips with different wettability and measured the nanobubbles with an identical setpoint. By comparing the force curves obtained during the measurements, it seems that the (middle-)hydrophobic tips penetrated the liquid/gas interface and received repulsive force resulting from positive meniscus formed by pinning at the tip surface. In contrast, hydrophilic tip didn't penetrate the interface and received the force from the deformation of the interface of the nanobubbles. In addition, the measurements using the (middle-)hydrophobic tips led to the underestimation of the nanobubbles profile corresponding to the pinning position at the tip surfaces.

Shape Comparison Between 0.4–2.0 and 20–60 lm Cement Particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holzer, L.; Flatt, R; Erdogan, S

Portland cement powder, ground from much larger clinker particles, has a particle size distribution from about 0.1 to 100 {micro}m. An important question is then: does particle shape depend on particle size? For the same cement, X-ray computed tomography has been used to examine the 3-D shape of particles in the 20-60 {micro}m sieve range, and focused ion beam nanotomography has been used to examine the 3-D shape of cement particles found in the 0.4-2.0 {micro}m sieve range. By comparing various kinds of computed particle shape data for each size class, the conclusion is made that, within experimental uncertainty, bothmore » size classes are prolate, but the smaller size class particles, 0.4-2.0 {micro}m, tend to be somewhat more prolate than the 20-60 {micro}m size class. The practical effect of this shape difference on the set-point was assessed using the Virtual Cement and Concrete Testing Laboratory to simulate the hydration of five cement powders. Results indicate that nonspherical aspect ratio is more important in determining the set-point than are the actual shape details.« less

PKPD model of interleukin-21 effects on thermoregulation in monkeys--application and evaluation of stochastic differential equations.

PubMed

Overgaard, Rune Viig; Holford, Nick; Rytved, Klaus A; Madsen, Henrik

2007-02-01

To describe the pharmacodynamic effects of recombinant human interleukin-21 (IL-21) on core body temperature in cynomolgus monkeys using basic mechanisms of heat regulation. A major effort was devoted to compare the use of ordinary differential equations (ODEs) with stochastic differential equations (SDEs) in pharmacokinetic pharmacodynamic (PKPD) modelling. A temperature model was formulated including circadian rhythm, metabolism, heat loss, and a thermoregulatory set-point. This model was formulated as a mixed-effects model based on SDEs using NONMEM. The effects of IL-21 were on the set-point and the circadian rhythm of metabolism. The model was able to describe a complex set of IL-21 induced phenomena, including 1) disappearance of the circadian rhythm, 2) no effect after first dose, and 3) high variability after second dose. SDEs provided a more realistic description with improved simulation properties, and further changed the model into one that could not be falsified by the autocorrelation function. The IL-21 induced effects on thermoregulation in cynomolgus monkeys are explained by a biologically plausible model. The quality of the model was improved by the use of SDEs.

BiliChek transcutaneous bilirubin meter overestimates serum bilirubin as measured by the Doumas reference method.

PubMed

Karon, Brad S; Wickremasinghe, Andrea C; Lo, Stanley F; Saenger, Amy K; Cook, Walter J

2010-08-01

To determine the relationship between BiliChek TcB (Respironics, Marietta GA) and Doumas reference serum or plasma total bilirubin (TSB). Pooled samples with values assigned by the Doumas reference method were used to establish the relationship between a local laboratory and reference Doumas TSB. We then established the relationship between TcB and TSB in the 3 months before and after reassignment of calibrator setpoints undertaken to match the local laboratory to Doumas reference bilirubin values. Before calibrator setpoint reassignment TSB as measured in our laboratory overestimated Doumas reference bilirubin. After calibrator adjustment laboratory TSB was within 1.7-6.8 micromol/L (0.1-0.4 mg/dL) of Doumas reference values. Mean bias between BiliChek TcB and TSB was 42.8+/-22.2 micromol/L (2.5+/-1.3mg/dL) (n=94) before and 49.6+/-22.2 micromol/L (2.9+/-1.3mg/dL) (n=115) after calibration adjustment. BiliChek TcB significantly overestimates TSB as measured by the Doumas reference method. 2010 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bartolac, S; Letourneau, D; University of Toronto, Toronto, Ontario

Purpose: Application of process control theory in quality assurance programs promises to allow earlier identification of problems and potentially better quality in delivery than traditional paradigms based primarily on tolerances and action levels. The purpose of this project was to characterize underlying seasonal variations in linear accelerator output that can be used to improve performance or trigger preemptive maintenance. Methods: Review of runtime plots of daily (6 MV) output data acquired using in house ion chamber based devices over three years and for fifteen linear accelerators of varying make and model were evaluated. Shifts in output due to known interventionsmore » with the machines were subtracted from the data to model an uncorrected scenario for each linear accelerator. Observable linear trends were also removed from the data prior to evaluation of periodic variations. Results: Runtime plots of output revealed sinusoidal, seasonal variations that were consistent across all units, irrespective of manufacturer, model or age of machine. The average amplitude of the variation was on the order of 1%. Peak and minimum variations were found to correspond to early April and September, respectively. Approximately 48% of output adjustments made over the period examined were potentially avoidable if baseline levels had corresponded to the mean output, rather than to points near a peak or valley. Linear trends were observed for three of the fifteen units, with annual increases in output ranging from 2–3%. Conclusion: Characterization of cyclical seasonal trends allows for better separation of potentially innate accelerator behaviour from other behaviours (e.g. linear trends) that may be better described as true out of control states (i.e. non-stochastic deviations from otherwise expected behavior) and could indicate service requirements. Results also pointed to an optimal setpoint for accelerators such that output of machines is maintained within set tolerances and interventions are required less frequently.« less

Stability analysis of a controlled mechanical system with parametric uncertainties in LuGre friction model

NASA Astrophysics Data System (ADS)

Sun, Yun-Hsiang; Sun, Yuming; Wu, Christine Qiong; Sepehri, Nariman

2018-04-01

Parameters of friction model identified for a specific control system development are not constants. They vary over time and have a significant effect on the control system stability. Although much research has been devoted to the stability analysis under parametric uncertainty, less attention has been paid to incorporating a realistic friction model into their analysis. After reviewing the common friction models for controller design, a modified LuGre friction model is selected to carry out the stability analysis in this study. Two parameters of the LuGre model, namely σ0 and σ1, are critical to the demonstration of dynamic friction features, yet the identification of which is difficult to carry out, resulting in a high level of uncertainties in their values. Aiming at uncovering the effect of the σ0 and σ1 variations on the control system stability, a servomechanism with modified LuGre friction model is investigated. Two set-point position controllers are synthesised based on the servomechanism model to form two case studies. Through Lyapunov exponents, it is clear that the variation of σ0 and σ1 has an obvious effect on the stabiltiy of the studied systems and should not be overlooked in the design phase.

Temperature control during regeneration of activated carbon fiber cloth with resistance-feedback.

PubMed

Johnsen, David L; Rood, Mark J

2012-10-16

Electrothermal swing adsorption (ESA) of organic compounds from gas streams with activated carbon fiber cloth (ACFC) reduces emissions to the atmosphere and recovers feedstock for reuse. Local temperature measurement (e.g., with a thermocouple) is typically used to monitor/control adsorbent regeneration cycles. Remote electrical resistance measurement is evaluated here as an alternative to local temperature measurement. ACFC resistance that was modeled based on its physical properties was within 10.5% of the measured resistance values during electrothermal heating. Resistance control was developed based on this measured relationship and used to control temperature to within 2.3% of regeneration set-point temperatures. Isobutane-laden adsorbent was then heated with resistance control. After 2 min of heating, the temperature of the adsorbent with isobutane was 13% less than the adsorbent without isobutane. This difference decreased to 2.1% after 9 min of heating, showing desorption of isobutane. An ACFC cartridge was also heated to 175 °C for 900 cycles with its resistance and adsorption capacity values remaining within 3% and 2%, respectively. This new method to control regeneration power application based on rapid sensing of the adsorbent's resistance removes the need for direct-contact temperature sensors providing a simple, cost-efficient, and long-term regeneration technique for ESA systems.

Generator voltage stabilisation for series-hybrid electric vehicles.

PubMed

Stewart, P; Gladwin, D; Stewart, J; Cowley, R

2008-04-01

This paper presents a controller for use in speed control of an internal combustion engine for series-hybrid electric vehicle applications. Particular reference is made to the stability of the rectified DC link voltage under load disturbance. In the system under consideration, the primary power source is a four-cylinder normally aspirated gasoline internal combustion engine, which is mechanically coupled to a three-phase permanent magnet AC generator. The generated AC voltage is subsequently rectified to supply a lead-acid battery, and permanent magnet traction motors via three-phase full bridge power electronic inverters. Two complementary performance objectives exist. Firstly to maintain the internal combustion engine at its optimal operating point, and secondly to supply a stable 42 V supply to the traction drive inverters. Achievement of these goals minimises the transient energy storage requirements at the DC link, with a consequent reduction in both weight and cost. These objectives imply constant velocity operation of the internal combustion engine under external load disturbances and changes in both operating conditions and vehicle speed set-points. An electronically operated throttle allows closed loop engine velocity control. System time delays and nonlinearities render closed loop control design extremely problematic. A model-based controller is designed and shown to be effective in controlling the DC link voltage, resulting in the well-conditioned operation of the hybrid vehicle.

High-stroke silicon-on-insulator MEMS nanopositioner: Control design for non-raster scan atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maroufi, Mohammad, E-mail: Mohammad.Maroufi@uon.edu.au; Fowler, Anthony G., E-mail: Anthony.Fowler@uon.edu.au; Bazaei, Ali, E-mail: Ali.Bazaei@newcastle.edu.au

A 2-degree of freedom microelectromechanical systems nanopositioner designed for on-chip atomic force microscopy (AFM) is presented. The device is fabricated using a silicon-on-insulator-based process and is designed as a parallel kinematic mechanism. It contains a central scan table and two sets of electrostatic comb actuators along each orthogonal axis, which provides displacement ranges greater than ±10 μm. The first in-plane resonance modes are located at 1274 Hz and 1286 Hz for the X and Y axes, respectively. To measure lateral displacements of the stage, electrothermal position sensors are incorporated in the design. To facilitate high-speed scans, the highly resonant dynamics ofmore » the system are controlled using damping loops in conjunction with internal model controllers that enable accurate tracking of fast sinusoidal set-points. To cancel the effect of sensor drift on controlled displacements, washout controllers are used in the damping loops. The feedback controlled nanopositioner is successfully used to perform several AFM scans in contact mode via a Lissajous scan method with a large scan area of 20 μm × 20 μm. The maximum scan rate demonstrated is 1 kHz.« less

Analysis of Control-Oriented Wake Modeling Tools Using Lidar Field Results

DOE PAGES

Annoni, Jennifer; Fleming, Paul; Scholbrock, Andrew; ...

2018-02-08

Wind turbines in a wind farm operate individually to maximize their own performance regardless of the impact of aerodynamic interactions on neighboring turbines. Wind farm controls can be used to increase power production or reduce overall structural loads by properly coordinating turbines. One wind farm control strategy that is addressed in literature is known as wake steering, wherein upstream turbines operate in yaw misaligned conditions to redirect their wakes away from downstream turbines. The National Renewable Energy Laboratory (NREL) in Golden, CO conducted a demonstration of wake steering on a single utility-scale turbine. In this study, the turbine was operatedmore » at various yaw misalignment setpoints while a lidar mounted on the nacelle scanned five downstream distances. The lidar measurements were combined with turbine data, as well as measurements of the inflow made by a highly instrumented meteorological mast upstream. The full-scale measurements are used to validate controls-oriented tools, including wind turbine wake models, used for wind farm controls and optimization. This paper presents a quantitative comparison of the lidar data and controls-oriented wake models under different atmospheric conditions and turbine operation. The results show good agreement between the lidar data and the models under these different conditions.« less

Analysis of Control-Oriented Wake Modeling Tools Using Lidar Field Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Annoni, Jennifer; Fleming, Paul; Scholbrock, Andrew

Wind turbines in a wind farm operate individually to maximize their own performance regardless of the impact of aerodynamic interactions on neighboring turbines. Wind farm controls can be used to increase power production or reduce overall structural loads by properly coordinating turbines. One wind farm control strategy that is addressed in literature is known as wake steering, wherein upstream turbines operate in yaw misaligned conditions to redirect their wakes away from downstream turbines. The National Renewable Energy Laboratory (NREL) in Golden, CO conducted a demonstration of wake steering on a single utility-scale turbine. In this study, the turbine was operatedmore » at various yaw misalignment setpoints while a lidar mounted on the nacelle scanned five downstream distances. The lidar measurements were combined with turbine data, as well as measurements of the inflow made by a highly instrumented meteorological mast upstream. The full-scale measurements are used to validate controls-oriented tools, including wind turbine wake models, used for wind farm controls and optimization. This paper presents a quantitative comparison of the lidar data and controls-oriented wake models under different atmospheric conditions and turbine operation. The results show good agreement between the lidar data and the models under these different conditions.« less

Feedback Linearization in a Six Degree-of-Freedom MAG-LEV Stage

NASA Technical Reports Server (NTRS)

Ludwick, Stephen J.; Trumper, David L.; Holmes, Michael L.

1996-01-01

A six degree-of-freedom electromagnetically suspended motion control stage (the Angstrom Stage) has been designed and constructed for use in short-travel, high-resolution motion control applications. It achieves better than 0.5 nm resolution over a 100 micron range of travel. The stage consists of a single moving element (the platen) floating in an oil filled chamber. The oil is crucial to the stage's operation since it forms squeeze film dampers between the platen and the frame. Twelve electromagnetic actuators provide the forces necessary to suspend and servo the platen, and six capacitance probes measure its position relative to the frame. The system is controlled using a digital signal processing board residing in a '486 based PC. This digital controller implements a feedback linearization algorithm in real-time to account for nonlinearities in both the magnetic actuators and the fluid film dampers. The feedback linearization technique reduces a highly nonlinear plant with coupling between the degrees of freedom into one that is linear, decoupled, and setpoint independent. The key to this procedure is a detailed plant model. The operation of the feedback linearization procedure is transparent to the outer loop of the controller, and so a proportional controller is sufficient for normal operation. We envision applications of this stage in scanned probe microscopy and for integrated circuit measurement.

Control strategies for wind farm power optimization: LES study

NASA Astrophysics Data System (ADS)

Ciri, Umberto; Rotea, Mario; Leonardi, Stefano

2017-11-01

Turbines in wind farms operate in off-design conditions as wake interactions occur for particular wind directions. Advanced wind farm control strategies aim at coordinating and adjusting turbine operations to mitigate power losses in such conditions. Coordination is achieved by controlling on upstream turbines either the wake intensity, through the blade pitch angle or the generator torque, or the wake direction, through yaw misalignment. Downstream turbines can be adapted to work in waked conditions and limit power losses, using the blade pitch angle or the generator torque. As wind conditions in wind farm operations may change significantly, it is difficult to determine and parameterize the variations of the coordinated optimal settings. An alternative is model-free control and optimization of wind farms, which does not require any parameterization and can track the optimal settings as conditions vary. In this work, we employ a model-free optimization algorithm, extremum-seeking control, to find the optimal set-points of generator torque, blade pitch and yaw angle for a three-turbine configuration. Large-Eddy Simulations are used to provide a virtual environment to evaluate the performance of the control strategies under realistic, unsteady incoming wind. This work was supported by the National Science Foundation, Grants No. 1243482 (the WINDINSPIRE project) and IIP 1362033 (I/UCRC WindSTAR). TACC is acknowledged for providing computational time.

Software architecture for a distributed real-time system in Ada, with application to telerobotics

NASA Technical Reports Server (NTRS)

Olsen, Douglas R.; Messiora, Steve; Leake, Stephen

1992-01-01

The architecture structure and software design methodology presented is described in the context of telerobotic application in Ada, specifically the Engineering Test Bed (ETB), which was developed to support the Flight Telerobotic Servicer (FTS) Program at GSFC. However, the nature of the architecture is such that it has applications to any multiprocessor distributed real-time system. The ETB architecture, which is a derivation of the NASA/NBS Standard Reference Model (NASREM), defines a hierarchy for representing a telerobot system. Within this hierarchy, a module is a logical entity consisting of the software associated with a set of related hardware components in the robot system. A module is comprised of submodules, which are cyclically executing processes that each perform a specific set of functions. The submodules in a module can run on separate processors. The submodules in the system communicate via command/status (C/S) interface channels, which are used to send commands down and relay status back up the system hierarchy. Submodules also communicate via setpoint data links, which are used to transfer control data from one submodule to another. A submodule invokes submodule algorithms (SMA's) to perform algorithmic operations. Data that describe or models a physical component of the system are stored as objects in the World Model (WM). The WM is a system-wide distributed database that is accessible to submodules in all modules of the system for creating, reading, and writing objects.

Is there resetting of central venous pressure in microgravity?

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Ludwig, D. A.; Elliott, J. J.; Wade, C. E.

2001-01-01

In the early phase of the Space Shuttle program, NASA flight surgeons implemented a fluid-loading countermeasure in which astronauts were instructed to ingest eight 1-g salt tablets with 960 ml of water approximately 2 hours prior to reentry from space. This fluid loading regimen was intended to enhance orthostatic tolerance by replacing circulating plasma volume reduced during the space mission. Unfortunately, fluid loading failed to replace plasma volume in groundbased experiments and has proven minimally effective as a countermeasure against post-spaceflight orthostatic intolerance. In addition to the reduction of plasma volume, central venous pressure (CVP) is reduced during exposure to actual and groundbased analogs of microgravity. In the present study, we hypothesized that the reduction in CVP due to exposure to microgravity represents a resetting of the CVP operating point to a lower threshold. A lower CVP 'setpoint' might explain the failure of fluid loading to restore plasma volume. In order to test this hypothesis, we conducted an investigation in which we administered an acute volume load (stimulus) and measured responses in CVP, plasma volume and renal functions. If our hypothesis is true, we would expect the elevation in CVP induced by saline infusion to return to its pre-infusion levels in both HDT and upright control conditions despite lower vascular volume during HDT. In contrast to previous experiments, our approach is novel in that it provides information on alterations in CVP and vascular volume during HDT that are necessary for interpretation of the proposed CVP operating point resetting hypothesis.

An Analysis of Electrical Consumption at Representative Army Installations.

DTIC Science & Technology

1980-05-01

can be done by analyzing and optimizing HVAC system and building operation. For example, if the minimum hourly usage (demand) of a typical bachelor...equipment. (Major candidates for scheduling are air-handler motors, chillers , air compressors, exhaust fans, exterior lights, hot water heaters, and hot...location: Thermostats Setpoint Measured Limiters Setback Area Temperature Temperature Yes No Yes No Are night setback thermostats recommended? Yes _ No

Automated Continuous Commissioning of Commercial Buildings

DTIC Science & Technology

2011-10-01

energy annually at the building level on two demonstration sites. Some faults would also cause issues related to thermal comfort . 2 $ Economizer...Unit (AHU) discharge air temperatures and room temperatures to deviate from their respective setpoints. This causes building thermal comfort issues...annual expenditure savings over the next three to five years. At the same time, the thermal comfort in DoD buildings would be improved to result in

Building America Case Study: Residential Mechanical Precooling, Roseville, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

A. German and M. Hoeschele

2017-05-01

Precooling is an operational strategy with potentially no up-front cost that cools occupied spaces earlier in the day to minimize or avoid afternoon air conditioner operation. In its simplest form, precooling can be implemented by scheduling air conditioner operation to reduce thermostat setpoints between 2 degrees and 6 degrees F below typical comfort settings in advance of the on-peak time period.

Building America Case Study: Residential Mechanical Precooling, Roseville, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

2017-05-08

Precooling is an operational strategy with potentially no up-front cost that cools occupied spaces earlier in the day to minimize or avoid afternoon air conditioner operation. In its simplest form, precooling can be implemented by scheduling air conditioner operation to reduce thermostat setpoints between 2 degrees and 6 degrees F below typical comfort settings in advance of the on-peak time period.

40 CFR Appendix B to Part 50 - Reference Method for the Determination of Suspended Particulate Matter in the Atmosphere (High...

Code of Federal Regulations, 2013 CFR

2013-07-01

... filters used are specified to have a minimum collection efficiency of 99 percent for 0.3 µm (DOP... electronic timers have much better set-point resolution than mechanical timers, but require a battery backup... Collection efficiency: 99 percent minimum as measured by the DOP test (ASTM-2986) for particles of 0.3 µm...

40 CFR Appendix B to Part 50 - Reference Method for the Determination of Suspended Particulate Matter in the Atmosphere (High...

Code of Federal Regulations, 2014 CFR

2014-07-01

... filters used are specified to have a minimum collection efficiency of 99 percent for 0.3 µm (DOP... electronic timers have much better set-point resolution than mechanical timers, but require a battery backup... Collection efficiency: 99 percent minimum as measured by the DOP test (ASTM-2986) for particles of 0.3 µm...

Predictive Optimal Control of Active and Passive Building Thermal Storage Inventory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gregor P. Henze; Moncef Krarti

2005-09-30

Cooling of commercial buildings contributes significantly to the peak demand placed on an electrical utility grid. Time-of-use electricity rates encourage shifting of electrical loads to off-peak periods at night and weekends. Buildings can respond to these pricing signals by shifting cooling-related thermal loads either by precooling the building's massive structure or the use of active thermal energy storage systems such as ice storage. While these two thermal batteries have been engaged separately in the past, this project investigated the merits of harnessing both storage media concurrently in the context of predictive optimal control. To pursue the analysis, modeling, and simulationmore » research of Phase 1, two separate simulation environments were developed. Based on the new dynamic building simulation program EnergyPlus, a utility rate module, two thermal energy storage models were added. Also, a sequential optimization approach to the cost minimization problem using direct search, gradient-based, and dynamic programming methods was incorporated. The objective function was the total utility bill including the cost of reheat and a time-of-use electricity rate either with or without demand charges. An alternative simulation environment based on TRNSYS and Matlab was developed to allow for comparison and cross-validation with EnergyPlus. The initial evaluation of the theoretical potential of the combined optimal control assumed perfect weather prediction and match between the building model and the actual building counterpart. The analysis showed that the combined utilization leads to cost savings that is significantly greater than either storage but less than the sum of the individual savings. The findings reveal that the cooling-related on-peak electrical demand of commercial buildings can be considerably reduced. A subsequent analysis of the impact of forecasting uncertainty in the required short-term weather forecasts determined that it takes only very simple short-term prediction models to realize almost all of the theoretical potential of this control strategy. Further work evaluated the impact of modeling accuracy on the model-based closed-loop predictive optimal controller to minimize utility cost. The following guidelines have been derived: For an internal heat gain dominated commercial building, reasonable geometry simplifications are acceptable without a loss of cost savings potential. In fact, zoning simplification may improve optimizer performance and save computation time. The mass of the internal structure did not show a strong effect on the optimization. Building construction characteristics were found to impact building passive thermal storage capacity. It is thus advisable to make sure the construction material is well modeled. Zone temperature setpoint profiles and TES performance are strongly affected by mismatches in internal heat gains, especially when they are underestimated. Since they are a key factor in determining the building cooling load, efforts should be made to keep the internal gain mismatch as small as possible. Efficiencies of the building energy systems affect both zone temperature setpoints and active TES operation because of the coupling of the base chiller for building precooling and the icemaking TES chiller. Relative efficiencies of the base and TES chillers will determine the balance of operation of the two chillers. The impact of mismatch in this category may be significant. Next, a parametric analysis was conducted to assess the effects of building mass, utility rate, building location and season, thermal comfort, central plant capacities, and an economizer on the cost saving performance of optimal control for active and passive building thermal storage inventory. The key findings are: (1) Heavy-mass buildings, strong-incentive time-of-use electrical utility rates, and large on-peak cooling loads will likely lead to attractive savings resulting from optimal combined thermal storage control. (2) By using economizer to take advantage of the cool fresh air during the night, the building electrical cost can be reduced by using less mechanical cooling. (3) Larger base chiller and active thermal storage capacities have the potential of shifting more cooling loads to off-peak hours and thus higher savings can be achieved. (4) Optimal combined thermal storage control with a thermal comfort penalty included in the objective function can improve the thermal comfort levels of building occupants when compared to the non-optimized base case. Lab testing conducted in the Larson HVAC Laboratory during Phase 2 showed that the EnergyPlus-based simulation was a surprisingly accurate prediction of the experiment. Therefore, actual savings of building energy costs can be expected by applying optimal controls from simulation results.« less

Robust model predictive control for optimal continuous drug administration.

PubMed

Sopasakis, Pantelis; Patrinos, Panagiotis; Sarimveis, Haralambos

2014-10-01

In this paper the model predictive control (MPC) technology is used for tackling the optimal drug administration problem. The important advantage of MPC compared to other control technologies is that it explicitly takes into account the constraints of the system. In particular, for drug treatments of living organisms, MPC can guarantee satisfaction of the minimum toxic concentration (MTC) constraints. A whole-body physiologically-based pharmacokinetic (PBPK) model serves as the dynamic prediction model of the system after it is formulated as a discrete-time state-space model. Only plasma measurements are assumed to be measured on-line. The rest of the states (drug concentrations in other organs and tissues) are estimated in real time by designing an artificial observer. The complete system (observer and MPC controller) is able to drive the drug concentration to the desired levels at the organs of interest, while satisfying the imposed constraints, even in the presence of modelling errors, disturbances and noise. A case study on a PBPK model with 7 compartments, constraints on 5 tissues and a variable drug concentration set-point illustrates the efficiency of the methodology in drug dosing control applications. The proposed methodology is also tested in an uncertain setting and proves successful in presence of modelling errors and inaccurate measurements. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

TFTR neutral beam control and monitoring for DT operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

O`Connor, T.; Kamperschroer, J.; Chu, J.

1995-12-31

Record fusion power output has recently been obtained in TFTR with the injection of deuterium and tritium neutral beams. This significant achievement was due in part to the controls, software, and data processing capabilities added to the neutral beam system for DT operations. Chief among these improvements was the addition of SUN workstations and large dynamic data storage to the existing Central Instrumentation Control and Data Acquisition (CICADA) system. Essentially instantaneous look back over the recent shot history has been provided for most beam waveforms and analysis results. Gas regulation controls allowing remote switchover between deuterium and tritium were alsomore » added. With these tools, comparison of the waveforms and data of deuterium and tritium for four test conditioning pulses quickly produced reliable tritium setpoints. Thereafter, all beam conditioning was performed with deuterium, thus saving the tritium supply for the important DT injection shots. The lookback capability also led to modifications of the gas system to improve reliability and to control ceramic valve leakage by backbiasing. Other features added to improve the reliability and availability of DT neutral beam operations included master beamline controls and displays, a beamline thermocouple interlock system, a peak thermocouple display, automatic gas inventory and cryo panel gas loading monitoring, beam notching controls, a display of beam/plasma interlocks, and a feedback system to control beam power based on plasma conditions.« less

Direct energy balance based active disturbance rejection control for coal-fired power plant.

PubMed

Sun, Li; Hua, Qingsong; Li, Donghai; Pan, Lei; Xue, Yali; Lee, Kwang Y

2017-09-01

The conventional direct energy balance (DEB) based PI control can fulfill the fundamental tracking requirements of the coal-fired power plant. However, it is challenging to deal with the cases when the coal quality variation is present. To this end, this paper introduces the active disturbance rejection control (ADRC) to the DEB structure, where the coal quality variation is deemed as a kind of unknown disturbance that can be estimated and mitigated promptly. Firstly, the nonlinearity of a recent power plant model is analyzed based on the gap metric, which provides guidance on how to set the pressure set-point in line with the power demand. Secondly, the approximate decoupling effect of the DEB structure is analyzed based on the relative gain analysis in frequency domain. Finally, the synthesis of the DEB based ADRC control system is carried out based on multi-objective optimization. The optimized ADRC results show that the integrated absolute error (IAE) indices of the tracking performances in both loops can be simultaneously improved, in comparison with the DEB based PI control and H ∞ control system. The regulation performance in the presence of the coal quality variation is significantly improved under the ADRC control scheme. Moreover, the robustness of the proposed strategy is shown comparable with the H ∞ control. Copyright © 2017. Published by Elsevier Ltd.

An algorithm for minimum-cost set-point ordering in a cryogenic wind tunnel

NASA Technical Reports Server (NTRS)

Tripp, J. S.

1981-01-01

An algorithm for minimum cost ordering of set points in a cryogenic wind tunnel is developed. The procedure generates a matrix of dynamic state transition costs, which is evaluated by means of a single-volume lumped model of the cryogenic wind tunnel and the use of some idealized minimum-costs, which is evaluated by means of a single-volume lumped model of the cryogenic wind tunnel and the use of some idealized minimum-cost state-transition control strategies. A branch and bound algorithm is employed to determine the least costly sequence of state transitions from the transition-cost matrix. Some numerical results based on data for the National Transonic Facility are presented which show a strong preference for state transitions that consume to coolant. Results also show that the choice of the terminal set point in an open odering can produce a wide variation in total cost.

Physiological mechanisms of thermoregulation in reptiles: a review.

PubMed

Seebacher, Frank; Franklin, Craig E

2005-11-01

The thermal dependence of biochemical reaction rates means that many animals regulate their body temperature so that fluctuations in body temperature are small compared to environmental temperature fluctuations. Thermoregulation is a complex process that involves sensing of the environment, and subsequent processing of the environmental information. We suggest that the physiological mechanisms that facilitate thermoregulation transcend phylogenetic boundaries. Reptiles are primarily used as model organisms for ecological and evolutionary research and, unlike in mammals, the physiological basis of many aspects in thermoregulation remains obscure. Here, we review recent research on regulation of body temperature, thermoreception, body temperature set-points, and cardiovascular control of heating and cooling in reptiles. The aim of this review is to place physiological thermoregulation of reptiles in a wider phylogenetic context. Future research on reptilian thermoregulation should focus on the pathways that connect peripheral sensing to central processing which will ultimately lead to the thermoregulatory response.

On-Line Control of Glucose Concentration in High-Yielding Mammalian Cell Cultures Enabled Through Oxygen Transfer Rate Measurements.

PubMed

Goldrick, Stephen; Lee, Kenneth; Spencer, Christopher; Holmes, William; Kuiper, Marcel; Turner, Richard; Farid, Suzanne S

2018-04-01

Glucose control is vital to ensure consistent growth and protein production in mammalian cell cultures. The typical fed-batch glucose control strategy involving bolus glucose additions based on infrequent off-line daily samples results in cells experiencing significant glucose concentration fluctuations that can influence product quality and growth. This study proposes an on-line method to control and manipulate glucose utilizing readily available process measurements. The method generates a correlation between the cumulative oxygen transfer rate and the cumulative glucose consumed. This correlation generates an on-line prediction of glucose that has been successfully incorporated into a control algorithm manipulating the glucose feed-rate. This advanced process control (APC) strategy enables the glucose concentration to be maintained at an adjustable set-point and has been found to significantly reduce the deviation in glucose concentration in comparison to conventional operation. This method has been validated to produce various therapeutic proteins across cell lines with different glucose consumption demands and is successfully demonstrated on micro (15 mL), laboratory (7 L), and pilot (50 L) scale systems. This novel APC strategy is simple to implement and offers the potential to significantly enhance the glucose control strategy for scales spanning micro-scale systems through to full scale industrial bioreactors. © 2018 The Authors. Biotechnology Journal Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Open source software to control Bioflo bioreactors.

PubMed

Burdge, David A; Libourel, Igor G L

2014-01-01

Bioreactors are designed to support highly controlled environments for growth of tissues, cell cultures or microbial cultures. A variety of bioreactors are commercially available, often including sophisticated software to enhance the functionality of the bioreactor. However, experiments that the bioreactor hardware can support, but that were not envisioned during the software design cannot be performed without developing custom software. In addition, support for third party or custom designed auxiliary hardware is often sparse or absent. This work presents flexible open source freeware for the control of bioreactors of the Bioflo product family. The functionality of the software includes setpoint control, data logging, and protocol execution. Auxiliary hardware can be easily integrated and controlled through an integrated plugin interface without altering existing software. Simple experimental protocols can be entered as a CSV scripting file, and a Python-based protocol execution model is included for more demanding conditional experimental control. The software was designed to be a more flexible and free open source alternative to the commercially available solution. The source code and various auxiliary hardware plugins are publicly available for download from https://github.com/LibourelLab/BiofloSoftware. In addition to the source code, the software was compiled and packaged as a self-installing file for 32 and 64 bit windows operating systems. The compiled software will be able to control a Bioflo system, and will not require the installation of LabVIEW.

Open Source Software to Control Bioflo Bioreactors

PubMed Central

Burdge, David A.; Libourel, Igor G. L.

2014-01-01

Bioreactors are designed to support highly controlled environments for growth of tissues, cell cultures or microbial cultures. A variety of bioreactors are commercially available, often including sophisticated software to enhance the functionality of the bioreactor. However, experiments that the bioreactor hardware can support, but that were not envisioned during the software design cannot be performed without developing custom software. In addition, support for third party or custom designed auxiliary hardware is often sparse or absent. This work presents flexible open source freeware for the control of bioreactors of the Bioflo product family. The functionality of the software includes setpoint control, data logging, and protocol execution. Auxiliary hardware can be easily integrated and controlled through an integrated plugin interface without altering existing software. Simple experimental protocols can be entered as a CSV scripting file, and a Python-based protocol execution model is included for more demanding conditional experimental control. The software was designed to be a more flexible and free open source alternative to the commercially available solution. The source code and various auxiliary hardware plugins are publicly available for download from https://github.com/LibourelLab/BiofloSoftware. In addition to the source code, the software was compiled and packaged as a self-installing file for 32 and 64 bit windows operating systems. The compiled software will be able to control a Bioflo system, and will not require the installation of LabVIEW. PMID:24667828

Improving a free air breathing proton exchange membrane fuel cell through the Maximum Efficiency Point Tracking method

NASA Astrophysics Data System (ADS)

Higuita Cano, Mauricio; Mousli, Mohamed Islam Aniss; Kelouwani, Sousso; Agbossou, Kodjo; Hammoudi, Mhamed; Dubé, Yves

2017-03-01

This work investigates the design and validation of a fuel cell management system (FCMS) which can perform when the fuel cell is at water freezing temperature. This FCMS is based on a new tracking technique with intelligent prediction, which combined the Maximum Efficiency Point Tracking with variable perturbation-current step and the fuzzy logic technique (MEPT-FL). Unlike conventional fuel cell control systems, our proposed FCMS considers the cold-weather conditions, the reduction of fuel cell set-point oscillations. In addition, the FCMS is built to respond quickly and effectively to the variations of electric load. A temperature controller stage is designed in conjunction with the MEPT-FL in order to operate the FC at low-temperature values whilst tracking at the same time the maximum efficiency point. The simulation results have as well experimental validation suggest that propose approach is effective and can achieve an average efficiency improvement up to 8%. The MEPT-FL is validated using a Proton Exchange Membrane Fuel Cell (PEMFC) of 500 W.

Hypothermic and antipyretic effects of ACTH (1-24) and alpha-melanotropin in guinea-pigs

NASA Technical Reports Server (NTRS)

Kandasamy, S. B.; Williams, B. A.

1984-01-01

Intracerebroventricular administration of adrenocorticotropin (ACTH 1-24) and alpha-melanotropin (alpha-MSH), peptides which occur naturally in brain induced dose-related hypothermia in guinea-pigs at room temperature (21 C) and also produced greater hypothermia at low (10 C) ambient temperature. However, when the experiments were repeated in a warm (30 C) environment, no effect on body temperature was observed. These results indicate that the peptides did not reduce the central set-point of temperature control. The hypothermia induced by ACTH and alpha-MSH was not mediated via histamine H1- or H2-receptors and serotonin since the H1-receptor antagonist, mepyramine, the H2-receptor antagonist, cimetidine, and the serotonin antagonist, methysergide, had no antagonistic effects. The peptides were antipyretic since they reduced pyrogen-induced-fever and hyperthermia due to prostaglandin E2, norepinephrine and dibutyryl cAMP, at a dose which did not affect normal body temperature. The powerful central effects of these peptides on normal body temperature, fever and hyperthermia, together with their presence of the brain regions important to temperature control, suggest that they participate in thermoregulation.

High Temperature Tribometer. Phase 1

DTIC Science & Technology

1989-06-01

13 Figure 2.3.2 Setpoint and Gain Windows in FW.EXE ......... . Figure 2.4.1 Data-Flow Diagram for Data-Acquisition Module ..... .. 23 I Figure...mounted in a friction force measuring device. Optimally , material testing results should not be test machine sensitiye; but due to equipment variables...fixed. The friction force due to sliding should be continuously measured. This is optimally done in conjunction with the normal force measurement via

Energy Conservation: Heating Navy Hangars

DTIC Science & Technology

1984-07-01

temperature, IF Tf Inside air temperature 1 foot above the floor, OF T. Inside design temperature, IF To Hot water temperature setpoint , OF TON Chiller ...systems capable of optimizing energy usage base-wide. An add-on to an existing large scale EMCS is probably the first preference, followed by single...the building comfort conditions are met during hours of building occupancy. 2. Optimized Start/Stop turns on equipment at the latest possible time and

Warming up human body by nanoporous metallized polyethylene textile.

PubMed

Cai, Lili; Song, Alex Y; Wu, Peilin; Hsu, Po-Chun; Peng, Yucan; Chen, Jun; Liu, Chong; Catrysse, Peter B; Liu, Yayuan; Yang, Ankun; Zhou, Chenxing; Zhou, Chenyu; Fan, Shanhui; Cui, Yi

2017-09-19

Space heating accounts for the largest energy end-use of buildings that imposes significant burden on the society. The energy wasted for heating the empty space of the entire building can be saved by passively heating the immediate environment around the human body. Here, we demonstrate a nanophotonic structure textile with tailored infrared (IR) property for passive personal heating using nanoporous metallized polyethylene. By constructing an IR-reflective layer on an IR-transparent layer with embedded nanopores, the nanoporous metallized polyethylene textile achieves a minimal IR emissivity (10.1%) on the outer surface that effectively suppresses heat radiation loss without sacrificing wearing comfort. This enables 7.1 °C decrease of the set-point compared to normal textile, greatly outperforming other radiative heating textiles by more than 3 °C. This large set-point expansion can save more than 35% of building heating energy in a cost-effective way, and ultimately contribute to the relief of global energy and climate issues.Energy wasted for heating the empty space of the entire building can be saved by passively heating the immediate environment around the human body. Here, the authors show a nanophotonic structure textile with tailored infrared property for passive personal heating using nanoporous metallized polyethylene.

Criticality as a Set-Point for Adaptive Behavior in Neuromorphic Hardware

PubMed Central

Srinivasa, Narayan; Stepp, Nigel D.; Cruz-Albrecht, Jose

2015-01-01

Neuromorphic hardware are designed by drawing inspiration from biology to overcome limitations of current computer architectures while forging the development of a new class of autonomous systems that can exhibit adaptive behaviors. Several designs in the recent past are capable of emulating large scale networks but avoid complexity in network dynamics by minimizing the number of dynamic variables that are supported and tunable in hardware. We believe that this is due to the lack of a clear understanding of how to design self-tuning complex systems. It has been widely demonstrated that criticality appears to be the default state of the brain and manifests in the form of spontaneous scale-invariant cascades of neural activity. Experiment, theory and recent models have shown that neuronal networks at criticality demonstrate optimal information transfer, learning and information processing capabilities that affect behavior. In this perspective article, we argue that understanding how large scale neuromorphic electronics can be designed to enable emergent adaptive behavior will require an understanding of how networks emulated by such hardware can self-tune local parameters to maintain criticality as a set-point. We believe that such capability will enable the design of truly scalable intelligent systems using neuromorphic hardware that embrace complexity in network dynamics rather than avoiding it. PMID:26648839

Performance comparison of optimal fractional order hybrid fuzzy PID controllers for handling oscillatory fractional order processes with dead time.

PubMed

Das, Saptarshi; Pan, Indranil; Das, Shantanu

2013-07-01

Fuzzy logic based PID controllers have been studied in this paper, considering several combinations of hybrid controllers by grouping the proportional, integral and derivative actions with fuzzy inferencing in different forms. Fractional order (FO) rate of error signal and FO integral of control signal have been used in the design of a family of decomposed hybrid FO fuzzy PID controllers. The input and output scaling factors (SF) along with the integro-differential operators are tuned with real coded genetic algorithm (GA) to produce optimum closed loop performance by simultaneous consideration of the control loop error index and the control signal. Three different classes of fractional order oscillatory processes with various levels of relative dominance between time constant and time delay have been used to test the comparative merits of the proposed family of hybrid fractional order fuzzy PID controllers. Performance comparison of the different FO fuzzy PID controller structures has been done in terms of optimal set-point tracking, load disturbance rejection and minimal variation of manipulated variable or smaller actuator requirement etc. In addition, multi-objective Non-dominated Sorting Genetic Algorithm (NSGA-II) has been used to study the Pareto optimal trade-offs between the set point tracking and control signal, and the set point tracking and load disturbance performance for each of the controller structure to handle the three different types of processes. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Integrated energy system for a high performance building

NASA Astrophysics Data System (ADS)

Jaczko, Kristen

Integrated energy systems have the potential to reduce of the energy consumption of residential buildings in Canada. These systems incorporate components to meet the building heating, cooling and domestic hot water load into a single system in order to reduce energy losses. An integrated energy system, consisting of a variable speed heat pump, cold and hot thermal storage tanks, a photovoltaic/thermal (PV/T) collector array and a battery bank, was designed for the Queen's Solar Design Team's (QSDT) test house. The system uses a radiant floor to provide space- heating and sensible cooling and a dedicated outdoor air system provides ventilation and dehumidifies the incoming fresh air. The test house, the Queen's Solar Education Centre (QSEC), and the integrated energy system were both modelled in TRNSYS. Additionally, a new TRNSYS Type was developed to model the PV/T collectors, enabling the modeling of the collection of energy from the ambient air. A parametric study was carried out in TRNSYS to investigate the effect of various parameters on the overall energy performance of the system. These parameters included the PV/T array size and the slope of the collectors, the heat pump source and load-side inlet temperature setpoints, the compressor speed control and the size of the thermal storage tanks and the battery bank. The controls of the heat pump were found to have a large impact on the performance of the integrated energy system. For example, a low evaporator setpoint improved the overall free energy ratio (FER) of the system but the heat pump performance was lowered. Reducing the heat loss of the PV/T panels was not found to have a large effect on the system performance however, as the heat pump is able to lower the inlet collector fluid temperature, thus reducing thermal losses. From the results of the sensitivity study, a recommended system model was created and this system had a predicted FER of 77.9% in Kingston, Ontario, neglecting the energy consumption of circulation pumps and fans. Simulations of the recommended integrated energy system were also performed in several other Canadian cities and the predicted FER was above 60% in all except for the most northern city investigated, Yellowknife. Thus, the integrated energy system has the potential of reducing the energy consumption of residential buildings in Canada.

Suction prevention and physiologic control of continuous flow left ventricular assist devices using intrinsic pump parameters.

PubMed

Wang, Yu; Koenig, Steven C; Slaughter, Mark S; Giridharan, Guruprasad A

2015-01-01

The risk for left ventricular (LV) suction during left ventricular assist devices (LVAD) support has been a clinical concern. Current development efforts suggest LVAD suction prevention and physiologic control algorithms may require chronic implantation of pressure or flow sensors, which can be unreliable because of baseline drift and short lifespan. To overcome this limitation, we designed a sensorless suction prevention and physiologic control (eSPPC) algorithm that only requires LVAD intrinsic parameters (pump speed and power). Two gain-scheduled, proportional-integral controllers maintain a differential pump speed (ΔRPM) above a user-defined threshold to prevent LV suction while maintaining an average reference differential pressure (ΔP) between the LV and aorta. ΔRPM is calculated from noisy pump speed measurements that are low-pass filtered, and ΔP is estimated using an extended Kalman filter. Efficacy and robustness of the eSPPC algorithm were evaluated in silico during simulated rest and exercise test conditions for 1) excessive ΔP setpoint (ES); 2) rapid eightfold increase in pulmonary vascular resistance (PVR); and 3) ES and PVR. Simulated hemodynamic waveforms (LV pressure and volume; aortic pressure and flow) using only intrinsic pump parameters showed the feasibility of our proposed eSPPC algorithm in preventing LV suction for all test conditions.

Field Test of Boiler Primary Loop Temperature Controller

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glanville, P.; Rowley, P.; Schroeder, D.

Beyond these initial system efficiency upgrades are an emerging class of Advanced Load Monitoring (ALM) aftermarket controllers that dynamically respond to the boiler load, with claims of 10% to 30% of fuel savings over a heating season. For hydronic boilers specifically, these devices perform load monitoring, with continuous measurement of supply and in some cases return water temperatures. Energy savings from these ALM controllers are derived from dynamic management of the boiler differential, where a microprocessor with memory of past boiler cycles prevents the boiler from firing for a period of time, to limit cycling losses and inefficient operation duringmore » perceived low load conditions. These differ from OTR controllers, which vary boiler setpoint temperatures with ambient conditions while maintaining a fixed differential. PARR installed and monitored the performance of one type of ALM controller, the M2G from Greffen Systems, at multifamily sites in the city of Chicago and its suburb Cary, IL, both with existing OTR control. Results show that energy savings depend on the degree to which boilers are over-sized for their load, represented by cycling rates. Also savings vary over the heating season with cycling rates, with greater savings observed in shoulder months. Over the monitoring period, over-sized boilers at one site showed reductions in cycling and energy consumption in line with prior laboratory studies, while less over-sized boilers at another site showed muted savings.« less

Standardized EMCS Energy Savings Calculations.

DTIC Science & Technology

1982-09-01

Reset 56 4.12 Boiler Optimization 57 4.13 Chiller Optimization 58 4.14 Chiller Water Temperature Reset 58 4.15 Condenser Water Temperature.Reset 59...gal, Btu/kwh, etc. (See page 32) 4.13 CHILLER OPTIMIZATION These savings are applicable only to chilled water plants with multiple chillers . The...temperature at end of shutdown period in OF To = hot water temperature setpoint in °F TON = chiller capacity in tons Ts = average temperature of surroundings in

Circadian Variation in Host Defense.

DTIC Science & Technology

1987-05-21

block fevers by Inhibiting the production of prostaglandins of the E series (PGE) In the hypothalamus , our data suggest to us that there is a circadian...Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP Key words: Interleukin-l, fever , circadian, rhythm, 08 body...to a rhythm in the thermoregulatory "set-point". The overall goal of our research was to determine whether this represents a circadian " fever ". If

Effect of human behavior on economizer efficacy and thermal comfort in southern California

NASA Astrophysics Data System (ADS)

Lanning, TIghe Glennon

California has set a zero net-energy conservation goal for the residential sector that is to be achieved by 2020 (California Energy Commission 2011). To reduce energy consumption in the building sector, modern buildings should fundamentally incorporate sustainable performance standards, involving renewable systems, climate-specific strategies, and consideration of a variety of users. Building occupants must operate in concert with the buildings they inhabit in order to maximize the potential of the building, its systems, and their own comfort. In climates with significant diurnal temperature swings, environmental controls designed to capitalize on this should be considered to reduce cooling-related loads. One specific strategy is the air-side economizer, which uses daily outdoor temperature swings to reduce indoor temperature swings. Traditionally a similar effect could be achieved by using thermal mass to buffer indoor temperature swings through thermal lag. Economizers reduce the amount of thermal mass typically required by naturally ventilated buildings. Fans are used to force cool nighttime air deep into the building, allowing lower mass buildings to take advantage of nighttime cooling. Economizers connect to a thermostat, and when the outdoor temperature dips below a programmed set-point the economizer draws cool air from outside, flushing out the warmed interior air. This type of system can be simulated with reasonable accuracy by energy modeling programs; however, because the system is occupant-driven (as opposed to a truly passive mass-driven system) any unpredictable occupant behavior can reduce its effectiveness and create misleading simulation results. This unpredictably has helped prevent the spread of economizers in the residential market. This study investigated to what extent human behavior affected the performance of economizer-based HVAC systems, based on physical observations, environmental data collections, and energy simulations of a residential building in Los Angeles, California. Tangible measures for alleviating problems, such as user-friendly interface design and the incorporation of human behavior into energy models are recommended based on these observations.

Circulating GLP-1 in infants born small-for-gestational-age: breast-feeding versus formula-feeding.

PubMed

Díaz, M; Bassols, J; Sebastiani, G; López-Bermejo, A; Ibáñez, L; de Zegher, F

2015-10-01

Prenatal growth restraint associates with the risk for later diabetes, particularly if such restraint is followed by postnatal formula-feeding (FOF) rather than breast-feeding (BRF). Circulating incretins can influence the neonatal programming of hypothalamic setpoints for appetite and energy expenditure, and are thus candidate mediators of the long-term effects exerted by early nutrition. We have tested this concept by measuring (at birth and at age 4 months) the circulating concentrations of glucagon-like peptide-1 (GLP-1) in BRF infants born appropriate-for-gestational-age (AGA; n=63) and in small-for-gestational-age (SGA) infants receiving either BRF (n=28) or FOF (n=26). At birth, concentrations of GLP-1 were similar in AGA and SGA infants. At 4 months, pre-feeding GLP-1 concentrations were higher than at birth; SGA-BRF infants had GLP-1 concentrations similar to those in AGA-BRF infants but SGA-FOF infants had higher concentrations. In conclusion, nutrition appears to influence the circulating GLP-1 concentrations in SGA infants and may thereby modulate long-term diabetes risk.

Composite hot drape forming

NASA Technical Reports Server (NTRS)

Ott, Thomas

1994-01-01

This program was initiated to replace labor-intensive ply-by-ply layup of composite I-beam posts and angle stiffeners used in the Space Station Freedom (SSF) rack structure. Hot drape forming (HDF) has been successfully implemented by BCAG for 777 composite I-stringers and by Bell Helicopter/Textron for the V-22 I-stingers. The two companies utilize two vastly different approaches to the I-beam fabrication process. A drape down process is used by Bell Helicopter where the compacted ply charge is placed on top of a forming mandrel and heated. When the heated ply charge reached a set temperature, vacuum pressure is applied and the plies are formed over the mandrel. The BCAG 777 process utilizes an inverted forming process where the ply stack is placed on a forming table and the mandrel is inverted and placed upon the ply stack. A heating and vacuum bladder underneath the ply stack form the play stack up onto the mandrels after reaching the temperature setpoint. Both methods have their advantages, but the drape down process was selected for SSF because it was more versatile and could be fabricated from readily available components.

Designing a Polymerase Chain Reaction Device Working with Radiation and Convection Heat Transfer

NASA Astrophysics Data System (ADS)

Madadelahi, M.; Kalan, K.; Shamloo, A.

2018-05-01

Gene proliferation is vital for infectious and genetic diseases diagnosis from a blood sample, even before birth. In addition, DNA sequencing, genetic finger-print analyzing, and genetic mutation detecting can be mentioned as other procedures requiring gene reproduction. Polymerase chain reaction, briefly known as PCR, is a convenient and effective way to accomplish this task; where the DNA containing sample faces three temperature phases alternatively. These phases are known as denaturation, annealing, and elongation/extension which in this study -regarding the type of the primers and the target DNA sequence- are set to occur at 95, 58, and 72 degrees of Celsius. In this study, a PCR device has been designed and fabricated which uses radiation and convection heat transfer at the same time to set and control the mentioned thermal sections. A 300W incandescent light bulb able to immediately turn off and on along with two 8×8 cm DC fans, controlled by a microcontroller as well as PID and PD controller codes are used to monitor the applied thermal cycles. In designing the controller codes it has been concerned that they not only control the temperature over the set-points as well as possible, but also increase the temperature variation rate between each two phases. The temperature data were plotted and DNA samples were used to assess the device function.

Theoretical Tools and Software for Modeling, Simulation and Control Design of Rocket Test Facilities

NASA Technical Reports Server (NTRS)

Richter, Hanz

2004-01-01

A rocket test stand and associated subsystems are complex devices whose operation requires that certain preparatory calculations be carried out before a test. In addition, real-time control calculations must be performed during the test, and further calculations are carried out after a test is completed. The latter may be required in order to evaluate if a particular test conformed to specifications. These calculations are used to set valve positions, pressure setpoints, control gains and other operating parameters so that a desired system behavior is obtained and the test can be successfully carried out. Currently, calculations are made in an ad-hoc fashion and involve trial-and-error procedures that may involve activating the system with the sole purpose of finding the correct parameter settings. The goals of this project are to develop mathematical models, control methodologies and associated simulation environments to provide a systematic and comprehensive prediction and real-time control capability. The models and controller designs are expected to be useful in two respects: 1) As a design tool, a model is the only way to determine the effects of design choices without building a prototype, which is, in the context of rocket test stands, impracticable; 2) As a prediction and tuning tool, a good model allows to set system parameters off-line, so that the expected system response conforms to specifications. This includes the setting of physical parameters, such as valve positions, and the configuration and tuning of any feedback controllers in the loop.

Fabrication Equipment for Periodic Material Assemblies and Ph Assemblies and Photonic Crystals (DURIP FY06)

DTIC Science & Technology

2008-04-29

An exhaust hood is necessary for binder removal. Cooling requires a fan at a second speed setpoint . Firing profiles need to be precisely...29,935.06 from Ohio match. Plasmalab 80 Plus Compact etching system (left) and heater/ chiller unit (right). CAHN TherMax 500 High Pressure TGA...the current research is aimed to optimize parameters of the structure, in order to improve the resonant properties of the periodic layered structures

Computer software configuration description, 241-AY and 241 AZ tank farm MICON automation system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Winkelman, W.D.

This document describes the configuration process, choices and conventions used during the Micon DCS configuration activities, and issues involved in making changes to the configuration. Includes the master listings of the Tag definitions, which should be revised to authorize any changes. Revision 3 provides additional information on the software used to provide communications with the W-320 project and incorporates minor changes to ensure the document alarm setpoint priorities correctly match operational expectations.

Steady-State and Dynamic Desorption of Organic Vapor From Activated Carbon With Electrothermal Swing Adsorption

DTIC Science & Technology

2007-06-01

41, 5063-5069 10.1021/es0703022 CCC: $37.00  2007 American Chemical Society VOL. 41, NO. 14, 2007 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 5063...system. 5064 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 41, NO. 14, 2007 occurred with variable pre-defined set-points ranging from 250 to 5000 ppmv...and (d) power and cumulative energy deposited to the ACFC. 5066 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 41, NO. 14, 2007 (Figure 4). Maximum

Simulation of process identification and controller tuning for flow control system

NASA Astrophysics Data System (ADS)

Chew, I. M.; Wong, F.; Bono, A.; Wong, K. I.

2017-06-01

PID controller is undeniably the most popular method used in controlling various industrial processes. The feature to tune the three elements in PID has allowed the controller to deal with specific needs of the industrial processes. This paper discusses the three elements of control actions and improving robustness of controllers through combination of these control actions in various forms. A plant model is simulated using the Process Control Simulator in order to evaluate the controller performance. At first, the open loop response of the plant is studied by applying a step input to the plant and collecting the output data from the plant. Then, FOPDT of physical model is formed by using both Matlab-Simulink and PRC method. Then, calculation of controller’s setting is performed to find the values of Kc and τi that will give satisfactory control in closed loop system. Then, the performance analysis of closed loop system is obtained by set point tracking analysis and disturbance rejection performance. To optimize the overall physical system performance, a refined tuning of PID or detuning is further conducted to ensure a consistent resultant output of closed loop system reaction to the set point changes and disturbances to the physical model. As a result, the PB = 100 (%) and τi = 2.0 (s) is preferably chosen for setpoint tracking while PB = 100 (%) and τi = 2.5 (s) is selected for rejecting the imposed disturbance to the model. In a nutshell, selecting correlation tuning values is likewise depended on the required control’s objective for the stability performance of overall physical model.

Differential flatness properties and adaptive control of the hypothalamic-pituitary-adrenal axis model

NASA Astrophysics Data System (ADS)

Rigatos, Gerasimos

2016-12-01

It is shown that the model of the hypothalamic-pituitary-adrenal gland axis is a differentially flat one and this permits to transform it to the so-called linear canonical form. For the new description of the system's dynamics the transformed control inputs contain unknown terms which depend on the system's parameters. To identify these terms an adaptive fuzzy approximator is used in the control loop. Thus an adaptive fuzzy control scheme is implemented in which the unknown or unmodeled system dynamics is approximated by neurofuzzy networks and next this information is used by a feedback controller that makes the state variables (CRH - corticotropin releasing hormone, adenocortocotropic hormone - ACTH, cortisol) of the hypothalamic-pituitary-adrenal gland axis model converge to the desirable levels (setpoints). This adaptive control scheme is exclusively implemented with the use of output feedback, while the state vector elements which are not directly measured are estimated with the use of a state observer that operates in the control loop. The learning rate of the adaptive fuzzy system is suitably computed from Lyapunov analysis, so as to assure that both the learning procedure for the unknown system's parameters, the dynamics of the observer and the dynamics of the control loop will remain stable. The performed Lyapunov stability analysis depends on two Riccati equations, one associated with the feedback controller and one associated with the state observer. Finally, it is proven that for the control scheme that comprises the feedback controller, the state observer and the neurofuzzy approximator, an H-infinity tracking performance can be succeeded.

A Smart Power Electronic Multiconverter for the Residential Sector.

PubMed

Guerrero-Martinez, Miguel Angel; Milanes-Montero, Maria Isabel; Barrero-Gonzalez, Fermin; Miñambres-Marcos, Victor Manuel; Romero-Cadaval, Enrique; Gonzalez-Romera, Eva

2017-05-26

The future of the grid includes distributed generation and smart grid technologies. Demand Side Management (DSM) systems will also be essential to achieve a high level of reliability and robustness in power systems. To do that, expanding the Advanced Metering Infrastructure (AMI) and Energy Management Systems (EMS) are necessary. The trend direction is towards the creation of energy resource hubs, such as the smart community concept. This paper presents a smart multiconverter system for residential/housing sector with a Hybrid Energy Storage System (HESS) consisting of supercapacitor and battery, and with local photovoltaic (PV) energy source integration. The device works as a distributed energy unit located in each house of the community, receiving active power set-points provided by a smart community EMS. This central EMS is responsible for managing the active energy flows between the electricity grid, renewable energy sources, storage equipment and loads existing in the community. The proposed multiconverter is responsible for complying with the reference active power set-points with proper power quality; guaranteeing that the local PV modules operate with a Maximum Power Point Tracking (MPPT) algorithm; and extending the lifetime of the battery thanks to a cooperative operation of the HESS. A simulation model has been developed in order to show the detailed operation of the system. Finally, a prototype of the multiconverter platform has been implemented and some experimental tests have been carried out to validate it.

A Smart Power Electronic Multiconverter for the Residential Sector

PubMed Central

Guerrero-Martinez, Miguel Angel; Milanes-Montero, Maria Isabel; Barrero-Gonzalez, Fermin; Miñambres-Marcos, Victor Manuel; Romero-Cadaval, Enrique; Gonzalez-Romera, Eva

2017-01-01

The future of the grid includes distributed generation and smart grid technologies. Demand Side Management (DSM) systems will also be essential to achieve a high level of reliability and robustness in power systems. To do that, expanding the Advanced Metering Infrastructure (AMI) and Energy Management Systems (EMS) are necessary. The trend direction is towards the creation of energy resource hubs, such as the smart community concept. This paper presents a smart multiconverter system for residential/housing sector with a Hybrid Energy Storage System (HESS) consisting of supercapacitor and battery, and with local photovoltaic (PV) energy source integration. The device works as a distributed energy unit located in each house of the community, receiving active power set-points provided by a smart community EMS. This central EMS is responsible for managing the active energy flows between the electricity grid, renewable energy sources, storage equipment and loads existing in the community. The proposed multiconverter is responsible for complying with the reference active power set-points with proper power quality; guaranteeing that the local PV modules operate with a Maximum Power Point Tracking (MPPT) algorithm; and extending the lifetime of the battery thanks to a cooperative operation of the HESS. A simulation model has been developed in order to show the detailed operation of the system. Finally, a prototype of the multiconverter platform has been implemented and some experimental tests have been carried out to validate it. PMID:28587131

Cost optimisation and minimisation of the environmental impact through life cycle analysis of the waste water treatment plant of Bree (Belgium).

PubMed

De Gussem, K; Wambecq, T; Roels, J; Fenu, A; De Gueldre, G; Van De Steene, B

2011-01-01

An ASM2da model of the full-scale waste water plant of Bree (Belgium) has been made. It showed very good correlation with reference operational data. This basic model has been extended to include an accurate calculation of environmental footprint and operational costs (energy consumption, dosing of chemicals and sludge treatment). Two optimisation strategies were compared: lowest cost meeting the effluent consent versus lowest environmental footprint. Six optimisation scenarios have been studied, namely (i) implementation of an online control system based on ammonium and nitrate sensors, (ii) implementation of a control on MLSS concentration, (iii) evaluation of internal recirculation flow, (iv) oxygen set point, (v) installation of mixing in the aeration tank, and (vi) evaluation of nitrate setpoint for post denitrification. Both an environmental impact or Life Cycle Assessment (LCA) based approach for optimisation are able to significantly lower the cost and environmental footprint. However, the LCA approach has some advantages over cost minimisation of an existing full-scale plant. LCA tends to chose control settings that are more logic: it results in a safer operation of the plant with less risks regarding the consents. It results in a better effluent at a slightly increased cost.

In situ combustion measurements of CO, H2O, and temperature with a 1.58-microm diode laser and two-tone frequency modulation.

PubMed

Nikkari, Jason J; Di, LorioJoannaM; Thomson, Murray J

2002-01-20

An optical near-infrared process sensor for electric are furnace pollution control and energy efficiency is proposed. A near-IR tunable diode laser has performed simultaneous in situ measurements of CO (1,577.96 nm), H2O (1,577.8 and 1,578.1 nm), and temperature in the exhaust gas region above a laboratory burner fueled with methane and propane. The applicable range of conditions tested is representative of those found in a commercial electric arc furnace and includes temperatures from 1,250 to 1,750 K, CO concentrations from 0 to 10%, and H20 concentrations from 3 to 27%. Two-tone frequency modulation was used to increase the detection sensitivity. An analysis of the method's accuracy has been conducted with 209 calibration and 105 unique test burner setpoints. Based on the standard deviation of differences between optical predictions and independently measured values, the minimum accuracy of the technique has been estimated as 36 K for temperature, 0.5% for CO, and 3% for H2O for all 105 test data points. This accuracy is sufficient for electric arc furnace control. The sensor's ability to nonintrusively measure CO and temperature in real time will allow for improved process control in this application.

Interpreting lateral dynamic weight shifts using a simple inverted pendulum model.

PubMed

Kennedy, Michael W; Bretl, Timothy; Schmiedeler, James P

2014-01-01

Seventy-five young, healthy adults completed a lateral weight-shifting activity in which each shifted his/her center of pressure (CoP) to visually displayed target locations with the aid of visual CoP feedback. Each subject's CoP data were modeled using a single-link inverted pendulum system with a spring-damper at the joint. This extends the simple inverted pendulum model of static balance in the sagittal plane to lateral weight-shifting balance. The model controlled pendulum angle using PD control and a ramp setpoint trajectory, and weight-shifting was characterized by both shift speed and a non-minimum phase (NMP) behavior metric. This NMP behavior metric examines the force magnitude at shift initiation and provides weight-shifting balance performance information that parallels the examination of peak ground reaction forces in gait analysis. Control parameters were optimized on a subject-by-subject basis to match balance metrics for modeled results to metric values calculated from experimental data. Overall, the model matches experimental data well (average percent error of 0.35% for shifting speed and 0.05% for NMP behavior). These results suggest that the single-link inverted pendulum model can be used effectively to capture lateral weight-shifting balance, as it has been shown to model static balance. Copyright © 2014 Elsevier B.V. All rights reserved.

Does carbon reduction increase sustainability? A study in wastewater treatment.

PubMed

Sweetapple, Christine; Fu, Guangtao; Butler, David

2015-12-15

This study investigates the relationships between carbon reduction and sustainability in the context of wastewater treatment, focussing on the impacts of control adjustments, and demonstrates that reducing energy use and/or increasing energy recovery to reduce net energy can be detrimental to sustainability. Factorial sampling is used to derive 315 control options, containing two different control strategies and a range of sludge wastage flow rates and dissolved oxygen setpoints, for evaluation. For each, sustainability indicators including operational costs, net energy and multiple environmental performance measures are calculated. This enables identification of trade-offs between different components of sustainability which must be considered before implementing energy reduction measures. In particular, it is found that the impacts of energy reduction measures on sludge production and nitrogen removal must be considered, as these are worsened in the lowest energy solutions. It also demonstrates that a sufficiently large range of indicators need to be assessed to capture trade-offs present within the environmental component of sustainability. This is because no solutions provided a move towards sustainability with respect to every indicator. Lastly, it is highlighted that improving the energy balance (as may be considered an approach to achieving carbon reduction) is not a reliable means of reducing total greenhouse gas emissions. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Behavioral thermoregulation by juvenile spring and fall chinook salmon, Oncorhynchus tshawytscha, during smoltification

USGS Publications Warehouse

Sauter, S.T.; Crawshaw, L.I.; Maule, A.G.

2001-01-01

Fall chinook salmon evolved to emigrate during the summer months. The shift in the temperature preference we observed in smolting fall chinook but not spring chinook salmon may reflect a phylogenetic adaptation to summer emigration by (1) providing directional orientation as fall chinook salmon move into the marine environment, (2) maintaining optimal gill function during emigration and seawater entry, and/or (3) resetting thermoregulatory set-points to support physiological homeostasis once smolted fish enter the marine environment. Phylogenetically determined temperature adaptations and responses to thermal stress may not protect fall chinook salmon from the recent higher summer water temperatures, altered annual thermal regimes, and degraded cold water refugia that result from hydropower regulation of the Columbia and Snake rivers. The long-term survival of fall chinook salmon will likely require restoration of normal annual thermographs and rigorous changes in land use practices to protect critical thermal refugia and control maximum summer water temperatures in reservoirs.

Equalizer system and method for series connected energy storing devices

DOEpatents

Rouillard, Jean; Comte, Christophe; Hagen, Ronald A.; Knudson, Orlin B.; Morin, Andre; Ross, Guy

1999-01-01

An apparatus and method for regulating the charge voltage of a number of electrochemical cells connected in series is disclosed. Equalization circuitry is provided to control the amount of charge current supplied to individual electrochemical cells included within the series string of electrochemical cells without interrupting the flow of charge current through the series string. The equalization circuitry balances the potential of each of the electrochemical cells to within a pre-determined voltage setpoint tolerance during charging, and, if necessary, prior to initiating charging. Equalization of cell potentials may be effected toward the end of a charge cycle or throughout the charge cycle. Overcharge protection is also provided for each of the electrochemical cells coupled to the series connection. During a discharge mode of operation in accordance with one embodiment, the equalization circuitry is substantially non-conductive with respect to the flow of discharge current from the series string of electrochemical cells. In accordance with another embodiment, equalization of the series string of cells is effected during a discharge cycle.

Building America Case Study: Advanced Boiler Load Monitoring Controllers, Chicago, Illinois (Fact Sheet)

DOE Office of Scientific and Technical Information (OSTI.GOV)

PARR

Beyond these initial system efficiency upgrades are an emerging class of Advanced Load Monitoring (ALM) aftermarket controllers that dynamically respond to the boiler load, with claims of 10% to 30% of fuel savings over a heating season. For hydronic boilers specifically, these devices perform load monitoring, with continuous measurement of supply and in some cases return water temperatures. Energy savings from these ALM controllers are derived from dynamic management of the boiler differential, where a microprocessor with memory of past boiler cycles prevents the boiler from firing for a period of time, to limit cycling losses and inefficient operation duringmore » perceived low load conditions. These differ from OTR controllers, which vary boiler setpoint temperatures with ambient conditions while maintaining a fixed differential. PARR installed and monitored the performance of one type of ALM controller, the M2G from Greffen Systems, at multifamily sites in the city of Chicago and its suburb Cary, IL, both with existing OTR control. Results show that energy savings depend on the degree to which boilers are over-sized for their load, represented by cycling rates. Also savings vary over the heating season with cycling rates, with greater savings observed in shoulder months. Over the monitoring period, over-sized boilers at one site showed reductions in cycling and energy consumption in line with prior laboratory studies, while less over-sized boilers at another site showed muted savings.« less

Cost optimization for buildings with hybrid ventilation systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Kun; Lu, Yan

A method including: computing a total cost for a first zone in a building, wherein the total cost is equal to an actual energy cost of the first zone plus a thermal discomfort cost of the first zone; and heuristically optimizing the total cost to identify temperature setpoints for a mechanical heating/cooling system and a start time and an end time of the mechanical heating/cooling system, based on external weather data and occupancy data of the first zone.

Intracerebroventricular Injection of Rats. A Sensitive Assay Method for Endogenous Pyrogen Circulating in Rats (41015)

DTIC Science & Technology

1981-01-01

Rats:1A Sensitive Assay Method for Endogenous Pyrogen Circulating in Rats (41015)1-- / WALTER J.CRITZ ~fI~ U.S. Army Medical Resetirch Inshfute- riak...8217ohn iases. F’oPy Detrick, Frederick. Maryland 21701 OI! Abstract, Intracerebroventricular tics) injection of endogenous pyrogen (EPI into rats causes...the lower the con- in an alteration of the "set-point" for body centration at which the pyrogen can be temperature (2). Endogenous pyrogen is a

Probabilistic Description of Fatigue Crack Growth Under Constant-and Variable-Amplitude Loading

DTIC Science & Technology

1989-03-01

plane, see figure 14. The length of the defected crack component and its angle, b and q, respectively, in Figure 15 were found to depend on the crack...length at which the defection occurs; as the crack length increases, b increases while q decreases. Due to the orientation of the deflected component...Breakpoint Voltage to Fun. Generator Output Setpoint Voltage Take Function Generator Gate High Start Test LNext page 153 Q! ~From last ag lastr DMAe 70

Flatness-based control in successive loops for stabilization of heart's electrical activity

NASA Astrophysics Data System (ADS)

Rigatos, Gerasimos; Melkikh, Alexey

2016-12-01

The article proposes a new flatness-based control method implemented in successive loops which allows for stabilization of the heart's electrical activity. Heart's pacemaking function is modeled as a set of coupled oscillators which potentially can exhibit chaotic behavior. It is shown that this model satisfies differential flatness properties. Next, the control and stabilization of this model is performed with the use of flatness-based control implemented in cascading loops. By applying a per-row decomposition of the state-space model of the coupled oscillators a set of nonlinear differential equations is obtained. Differential flatness properties are shown to hold for the subsystems associated with the each one of the aforementioned differential equations and next a local flatness-based controller is designed for each subsystem. For the i-th subsystem, state variable xi is chosen to be the flat output and state variable xi+1 is taken to be a virtual control input. Then the value of the virtual control input which eliminates the output tracking error for the i-th subsystem becomes reference setpoint for the i + 1-th subsystem. In this manner the control of the entire state-space model is performed by successive flatness-based control loops. By arriving at the n-th row of the state-space model one computes the control input that can be actually exerted on the aforementioned biosystem. This real control input of the coupled oscillators' system, contains recursively all virtual control inputs associated with the previous n - 1 rows of the state-space model. This control approach achieves asymptotically the elimination of the chaotic oscillation effects and the stabilization of the heart's pulsation rhythm. The stability of the proposed control scheme is proven with the use of Lyapunov analysis.

System properties, feedback control and effector coordination of human temperature regulation.

PubMed

Werner, Jürgen

2010-05-01

The aim of human temperature regulation is to protect body processes by establishing a relative constancy of deep body temperature (regulated variable), in spite of external and internal influences on it. This is basically achieved by a distributed multi-sensor, multi-processor, multi-effector proportional feedback control system. The paper explains why proportional control implies inherent deviations of the regulated variable from the value in the thermoneutral zone. The concept of feedback of the thermal state of the body, conveniently represented by a high-weighted core temperature (T (c)) and low-weighted peripheral temperatures (T (s)) is equivalent to the control concept of "auxiliary feedback control", using a main (regulated) variable (T (c)), supported by an auxiliary variable (T (s)). This concept implies neither regulation of T (s) nor feedforward control. Steady-states result in the closed control-loop, when the open-loop properties of the (heat transfer) process are compatible with those of the thermoregulatory processors. They are called operating points or balance points and are achieved due to the inherent property of dynamical stability of the thermoregulatory feedback loop. No set-point and no comparison of signals (e.g. actual-set value) are necessary. Metabolic heat production and sweat production, though receiving the same information about the thermal state of the body, are independent effectors with different thresholds and gains. Coordination between one of these effectors and the vasomotor effector is achieved by the fact that changes in the (heat transfer) process evoked by vasomotor control are taken into account by the metabolic/sweat processor.

Heating, ventilation and air conditioning system optimization: a study of the effect of climate, building design, system selection and control strategy on the energy consumption of a typical office building in London and Athens

NASA Astrophysics Data System (ADS)

Spasis, Georgios

The increasing demand for air conditioning in commercial buildings imposes a serious threat to Europe's CO2 reduction targets. Architects and engineers are therefore in a key position to help reduce the impact of buildings on the environment by taking appropriate decisions concerning the design of the building and the associated heating, ventilation and air conditioning (HVAC) system. The thesis studies the effect of a number of building and HVAC system related design factors on the energy performance of a notional air-conditioned office building employing either a variable air volume (VAV) system with terminal re-heaters, or a four-pipe fan coil unit (FCU) system with fresh air supply from a central plant, using mainly a dynamic simulation tool and the response surface methodology. The evaluation of the energy performance of the HVAC systems is for two types of climate, using typical weather data for London (UK) and Athens (Greece). It has been found that the design variables associated with the solar radiation through the transparent building elements and the internal heat gains should be the main concern of the building designer. On the other hand, the HVAC system engineer should give emphasis to the parameters associated with the plant performance and operation, as well as the temperature control set-points. It has been shown that it is possible to reduce the carbon emissions of the base case scenario by up to 88% depending on the HVAC system and the climate for which it is simulated. The carbon savings, however, are reduced by up to 22% where humidification is provided. This reduction differs depending on the HVAC system and the climatic conditions. The VAV system is more energy efficient than the FCU system, mainly due to the exploitation of the free cooling capacity of the outdoor air. The difference in carbon emissions between the two systems drops when both of them are simulated for the Athens as opposed to the London typical weather conditions. It has been found that it is possible to turn the carbon scales in favour of the FCU system when humidification to a high RH set-point is provided throughout the year, since the adjustment of the RH of the air is particularly energy wasteful for the VAV system.

Genome-wide scan for commons SNPs affecting bovine leukemia virus infection level in dairy cattle.

PubMed

Carignano, Hugo A; Roldan, Dana L; Beribe, María J; Raschia, María A; Amadio, Ariel; Nani, Juan P; Gutierrez, Gerónimo; Alvarez, Irene; Trono, Karina; Poli, Mario A; Miretti, Marcos M

2018-02-13

Bovine leukemia virus (BLV) infection is omnipresent in dairy herds causing direct economic losses due to trade restrictions and lymphosarcoma-related deaths. Milk production drops and increase in the culling rate are also relevant and usually neglected. The BLV provirus persists throughout a lifetime and an inter-individual variation is observed in the level of infection (LI) in vivo. High LI is strongly correlated with disease progression and BLV transmission among herd mates. In a context of high prevalence, classical control strategies are economically prohibitive. Alternatively, host genomics studies aiming to dissect loci associated with LI are potentially useful tools for genetic selection programs tending to abrogate the viral spreading. The LI was measured through the proviral load (PVL) set-point and white blood cells (WBC) counts. The goals of this work were to gain insight into the contribution of SNPs (bovine 50KSNP panel) on LI variability and to identify genomics regions underlying this trait. We quantified anti-p24 response and total leukocytes count in peripheral blood from 1800 cows and used these to select 800 individuals with extreme phenotypes in WBCs and PVL. Two case-control genomic association studies using linear mixed models (LMMs) considering population stratification were performed. The proportion of the variance captured by all QC-passed SNPs represented 0.63 (SE ± 0.14) of the phenotypic variance for PVL and 0.56 (SE ± 0.15) for WBCs. Overall, significant associations (Bonferroni's corrected -log 10 p > 5.94) were shared for both phenotypes by 24 SNPs within the Bovine MHC. Founder haplotypes were used to measure the linkage disequilibrium (LD) extent (r 2  = 0.22 ± 0.27 at inter-SNP distance of 25-50 kb). The SNPs and LD blocks indicated genes potentially associated with LI in infected cows: i.e. relevant immune response related genes (DQA1, DRB3, BOLA-A, LTA, LTB, TNF, IER3, GRP111, CRISP1), several genes involved in cell cytoskeletal reorganization (CD2AP, PKHD1, FLOT1, TUBB5) and modelling of the extracellular matrix (TRAM2, TNXB). Host transcription factors (TFs) were also highlighted (TFAP2D; ABT1, GCM1, PRRC2A). Data obtained represent a step forward to understand the biology of BLV-bovine interaction, and provide genetic information potentially applicable to selective breeding programs.

A Simple Rule for Dendritic Spine and Axonal Bouton Formation Can Account for Cortical Reorganization after Focal Retinal Lesions

PubMed Central

Butz, Markus; van Ooyen, Arjen

2013-01-01

Lasting alterations in sensory input trigger massive structural and functional adaptations in cortical networks. The principles governing these experience-dependent changes are, however, poorly understood. Here, we examine whether a simple rule based on the neurons' need for homeostasis in electrical activity may serve as driving force for cortical reorganization. According to this rule, a neuron creates new spines and boutons when its level of electrical activity is below a homeostatic set-point and decreases the number of spines and boutons when its activity exceeds this set-point. In addition, neurons need a minimum level of activity to form spines and boutons. Spine and bouton formation depends solely on the neuron's own activity level, and synapses are formed by merging spines and boutons independently of activity. Using a novel computational model, we show that this simple growth rule produces neuron and network changes as observed in the visual cortex after focal retinal lesions. In the model, as in the cortex, the turnover of dendritic spines was increased strongest in the center of the lesion projection zone, while axonal boutons displayed a marked overshoot followed by pruning. Moreover, the decrease in external input was compensated for by the formation of new horizontal connections, which caused a retinotopic remapping. Homeostatic regulation may provide a unifying framework for understanding cortical reorganization, including network repair in degenerative diseases or following focal stroke. PMID:24130472

Towards a quantitative description of tunneling conductance of superconductors: Application to LiFeAs

DOE PAGES

Kreisel, A.; Nelson, R.; Berlijn, T.; ...

2016-12-27

Since the discovery of iron-based superconductors, a number of theories have been put forward to explain the qualitative origin of pairing, but there have been few attempts to make quantitative, material-specific comparisons to experimental results. The spin-fluctuation theory of electronic pairing, based on first-principles electronic structure calculations, makes predictions for the superconducting gap. Within the same framework, the surface wave functions may also be calculated, allowing, e.g., for detailed comparisons between theoretical results and measured scanning tunneling topographs and spectra. We present such a comparison between theory and experiment on the Fe-based superconductor LiFeAs. Our results for the homogeneous surfacemore » as well as impurity states are presented as a benchmark test of the theory. For the homogeneous system, we argue that the maxima of topographic image intensity may be located at positions above either the As or Li atoms, depending on tip height and the setpoint current of the measurement. We further report the experimental observation of transitions between As- and Li-registered lattices as functions of both tip height and setpoint bias, in agreement with this prediction. Next, we give a detailed comparison between the simulated scanning tunneling microscopy images of transition-metal defects with experiment. Finally, we discuss possible extensions of the current framework to obtain a theory with true predictive power for scanning tunneling microscopy in Fe-based systems.« less

Towards a quantitative description of tunneling conductance of superconductors: Application to LiFeAs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kreisel, A.; Nelson, R.; Berlijn, T.

Since the discovery of iron-based superconductors, a number of theories have been put forward to explain the qualitative origin of pairing, but there have been few attempts to make quantitative, material-specific comparisons to experimental results. The spin-fluctuation theory of electronic pairing, based on first-principles electronic structure calculations, makes predictions for the superconducting gap. Within the same framework, the surface wave functions may also be calculated, allowing, e.g., for detailed comparisons between theoretical results and measured scanning tunneling topographs and spectra. We present such a comparison between theory and experiment on the Fe-based superconductor LiFeAs. Our results for the homogeneous surfacemore » as well as impurity states are presented as a benchmark test of the theory. For the homogeneous system, we argue that the maxima of topographic image intensity may be located at positions above either the As or Li atoms, depending on tip height and the setpoint current of the measurement. We further report the experimental observation of transitions between As- and Li-registered lattices as functions of both tip height and setpoint bias, in agreement with this prediction. Next, we give a detailed comparison between the simulated scanning tunneling microscopy images of transition-metal defects with experiment. Finally, we discuss possible extensions of the current framework to obtain a theory with true predictive power for scanning tunneling microscopy in Fe-based systems.« less

Wnt/Notum spatial feedback inhibition controls neoblast differentiation to regulate reversible growth of the planarian brain

PubMed Central

Hill, Eric M.; Petersen, Christian P.

2015-01-01

Mechanisms determining final organ size are poorly understood. Animals undergoing regeneration or ongoing adult growth are likely to require sustained and robust mechanisms to achieve and maintain appropriate sizes. Planarians, well known for their ability to undergo whole-body regeneration using pluripotent adult stem cells of the neoblast population, can reversibly scale body size over an order of magnitude by controlling cell number. Using quantitative analysis, we showed that after injury planarians perfectly restored brain:body proportion by increasing brain cell number through epimorphosis or decreasing brain cell number through tissue remodeling (morphallaxis), as appropriate. We identified a pathway controlling a brain size set-point that involves feedback inhibition between wnt11-6/wntA/wnt4a and notum, encoding conserved antagonistic signaling factors expressed at opposite brain poles. wnt11-6/wntA/wnt4a undergoes feedback inhibition through canonical Wnt signaling but is likely to regulate brain size in a non-canonical pathway independently of beta-catenin-1 and APC. Wnt/Notum signaling tunes numbers of differentiated brain cells in regenerative growth and tissue remodeling by influencing the abundance of brain progenitors descended from pluripotent stem cells, as opposed to regulating cell death. These results suggest that the attainment of final organ size might be accomplished by achieving a balance of positional signaling inputs that regulate the rates of tissue production. PMID:26525673

Effects of skylight parameters on daylighting energy savings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arasteh, D.; Johnson, R.; Selkowitz, S.

1985-05-01

Skylight parameters that affect lighting, cooling, heating, fan, and total energy use in office buildings are examined using the state-of-the-art building energy analysis computer code, DOE-2.1B. The lighting effects of skylight spatial distribution, skylight area, skylight visible transmission, well factor, illumination setpoint, interior partitions, ceiling height, and glazing characteristics are discussed. This study serves as the foundation for the creation of a DOE-2.1B data base and design tools for estimating daylighting energy savings from skylights. 13 refs., 9 figs., 1 tab.

Design of a Pilot Plant for Vacuum Infusion of High Lipoidal Liquids into Dried Foods

DTIC Science & Technology

1988-07-01

on a conveyor belt equipped with a chiller hood. /". 20 DISTRIBUTION’AVAILABILITY OF ABSTRACT SUNCLASSlFlEn’VL’V’S:» Q jwj AS RB" U DtiC US...design is an optimization of design criteria, shown in Figure I. In addition to the basic design criteria, the equipment must operate within a...the desired setpoint . 2.2 Lipoidal Liquid Systems; The lipoidal liquid is provided at the proper conditions to the immersion dish from an

Integrally regulated solar array demonstration using an Intel 8080 microprocessor

NASA Technical Reports Server (NTRS)

Petrik, E. J.

1977-01-01

A concept for regulating the voltage of a solar array by using a microprocessor to effect discrete voltage changes was demonstrated. Eight shorting switches were employed to regulate a simulated array at set-point voltages between 10,000 and 15,000 volts. The demonstration showed that the microprocessor easily regulated the solar array output voltage independently of whether or not the switched cell groups were binary sized in voltage. In addition, the microprocessor provided logic memory capability to perform additional tasks such as locating and insolating a faulty switch.

Simulation of future global warming scenarios in rice paddies with an open-field warming facility

PubMed Central

2011-01-01

To simulate expected future global warming, hexagonal arrays of infrared heaters have previously been used to warm open-field canopies of upland crops such as wheat. Through the use of concrete-anchored posts, improved software, overhead wires, extensive grounding, and monitoring with a thermal camera, the technology was safely and reliably extended to paddy rice fields. The system maintained canopy temperature increases within 0.5°C of daytime and nighttime set-point differences of 1.3 and 2.7°C 67% of the time. PMID:22145582

Depot- and sex-specific effects of maternal obesity in offspring's adipose tissue.

PubMed

Lecoutre, Simon; Deracinois, Barbara; Laborie, Christine; Eberlé, Delphine; Guinez, Céline; Panchenko, Polina E; Lesage, Jean; Vieau, Didier; Junien, Claudine; Gabory, Anne; Breton, Christophe

2016-07-01

According to the Developmental Origin of Health and Disease (DOHaD) concept, alterations of nutrient supply in the fetus or neonate result in long-term programming of individual body weight (BW) setpoint. In particular, maternal obesity, excessive nutrition, and accelerated growth in neonates have been shown to sensitize offspring to obesity. The white adipose tissue may represent a prime target of metabolic programming induced by maternal obesity. In order to unravel the underlying mechanisms, we have developed a rat model of maternal obesity using a high-fat (HF) diet (containing 60% lipids) before and during gestation and lactation. At birth, newborns from obese dams (called HF) were normotrophs. However, HF neonates exhibited a rapid weight gain during lactation, a key period of adipose tissue development in rodents. In males, increased BW at weaning (+30%) persists until 3months of age. Nine-month-old HF male offspring was normoglycemic but showed mild glucose intolerance, hyperinsulinemia, and hypercorticosteronemia. Despite no difference in BW and energy intake, HF adult male offspring was predisposed to fat accumulation showing increased visceral (gonadal and perirenal) depots weights and hyperleptinemia. However, only perirenal adipose tissue depot exhibited marked adipocyte hypertrophy and hyperplasia with elevated lipogenic (i.e. sterol-regulated element binding protein 1 (Srebp1), fatty acid synthase (Fas), and leptin) and diminished adipogenic (i.e. peroxisome proliferator-activated receptor gamma (Pparγ), 11β-hydroxysteroid dehydrogenase type 1 (11β-Hds1)) mRNA levels. By contrast, very few metabolic variations were observed in HF female offspring. Thus, maternal obesity and accelerated growth during lactation program offspring for higher adiposity via transcriptional alterations of visceral adipose tissue in a depot- and sex-specific manner. © 2016 Society for Endocrinology.

An analog RF gap voltage regulation system for the Advanced Photon Source storage ring.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horan, D.

1999-04-13

An analog rf gap voltage regulation system has been designed and built at Argonne National Laboratory to maintain constant total storage ring rf gap voltage, independent of beam loading and cavity tuning effects. The design uses feedback control of the klystron mod-anode voltage to vary the amount of rf power fed to the storage ring cavities. The system consists of two independent feedback loops, each regulating the combined rf gap voltages of eight storage ring cavities by varying the output power of either one or two rf stations, depending on the mode of operation. It provides full operator control andmore » permissive logic to permit feedback control of the rf system output power only if proper conditions are met. The feedback system uses envelope-detected cavity field probe outputs as the feedback signal. Two different methods of combining the individual field probe signals were used to generate a relative DC level representing one-half of the total storage ring rf voltage, an envelope-detected vector sum of the field probe rf signals, and the DC sum of individual field probe envelope detector outputs. The merits of both methods are discussed. The klystron high-voltage power supply (HVPS) units are fitted with an analog interface for external control of the mod-anode voltage level, using a four-quadrant analog multiplier to modulate the HVPS mod-anode voltage regulator set-point in response to feedback system commands.« less

Fuzzy control for a nonlinear mimo-liquid level problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R. E.; Mortensen, F. N.; Wantuck, P. J.

2001-01-01

Nonlinear systems are very common in the chemical process industries. Control of these systems, particularly multivariable systems, is extremely difficult. In many chemical plants, because of this difficulty, control is seldom optimal. Quite often, the best control is obtained in the manual mode using experienced operators. Liquid level control is probably one of the most common control problems in a chemical plant. Liquid level is important in heat exchanger control where heat and mass transfer rates can be controlled by the amount of liquid covering the tubes. Distillation columns, mixing tanks, and surge tanks are other examples where liquid levelmore » control is very important. The problem discussed in this paper is based on the simultaneous level control of three tanks connected in series. Each tank holds slightly less than 0.01 m{sup 3} of liquid. All three tanks are connected, Liquid is pumped into the first and the third tanks to maintain their levels. The third tank in the series drains to the system exit. The levels in the first and third tank control the level in the middle tank. The level in the middle tank affects the levels in the two end tanks. Many other chemical plant systems can be controlled in a manner similar to this three-tank system. For example, in any distillation column liquid level control problems can be represented as a total condenser with liquid level control, a reboiler with liquid level control, with the interactive column in between. The solution to the three-tank-problem can provide insight into many of the nonlinear control problems in the chemical process industries. The system was tested using the fuzzy logic controller and a proportional-integral (PI) controller, in both the setpoint tracking mode and disturbance rejection mode. The experimental results are discussed and comparisons between fuzzy controller and the standard PI controller are made.« less

Monitoring soft tissue coagulation by optical spectroscopy

NASA Astrophysics Data System (ADS)

Lihachev, A.; Lihacova, I.; Heinrichs, H.; Spigulis, J.; Trebst, T.; Wehner, M.

2017-12-01

Laser tissue welding (LTW) or laser tissue soldering (LTS) is investigated since many years for treatment of incisions, wound closure and anastomosis of vessels [1, 2]. Depending on the process, a certain temperature in the range between 65 °C to 85 °C must be reached and held for a few seconds. Care has to be taken not to overheat the tissue, otherwise necrosis or tissue carbonization may occur and will impair wound healing. Usually the temperature is monitored during the process to control the laser power [3]. This requires either bulky equipment or expensive and fragile infrared fibers to feed the temperature signal to an infrared detector. Alternatively, changes in tissue morphology can be directly observed by analysis of spectral reflectance. We investigate spectral changes in the range between 400 nm to 900 nm wavelength. Characteristic spectral changes occur when the temperature of tissue samples increase above 70 °C which is a typical setpoint value for temperature control of coagulation. We conclude that simple spectroscopy in the visible range can provide valuable information during LTS and LTW and probably replace the delicate measurement of temperature. A major advantage is that optical measurements can be performed using standard optical fibers and can be easily integrated into a surgical tool.

Modelling energy costs for different operational strategies of a large water resource recovery facility.

PubMed

Póvoa, P; Oehmen, A; Inocêncio, P; Matos, J S; Frazão, A

2017-05-01

The main objective of this paper is to demonstrate the importance of applying dynamic modelling and real energy prices on a full scale water resource recovery facility (WRRF) for the evaluation of control strategies in terms of energy costs with aeration. The Activated Sludge Model No. 1 (ASM1) was coupled with real energy pricing and a power consumption model and applied as a dynamic simulation case study. The model calibration is based on the STOWA protocol. The case study investigates the importance of providing real energy pricing comparing (i) real energy pricing, (ii) weighted arithmetic mean energy pricing and (iii) arithmetic mean energy pricing. The operational strategies evaluated were (i) old versus new air diffusers, (ii) different DO set-points and (iii) implementation of a carbon removal controller based on nitrate sensor readings. The application in a full scale WRRF of the ASM1 model coupled with real energy costs was successful. Dynamic modelling with real energy pricing instead of constant energy pricing enables the wastewater utility to optimize energy consumption according to the real energy price structure. Specific energy cost allows the identification of time periods with potential for linking WRRF with the electric grid to optimize the treatment costs, satisfying operational goals.

Ballistocraft: a novel facility for microgravity research.

PubMed

Mesland, D; Paris, D; Huijser, R; Lammertse, P; Postema, R

1995-05-01

One of ESA's aims is to provide the microgravity research community with various microgravity exposure facilities. Those facilities include drop towers, sounding rockets, and parabolic flights on board aircraft, in addition to orbital spacecraft. Microgravity flights are usually achieved using large aircraft like the French 'Caravelle' that offer a large payload volume and where a person can be present to perform the experiments and to participate as a human test-subject. However, the microgravity community is also very interested in a flexible, complementary facility that would allow frequent and repetitive exposure to microgravity for a laboratory-type of payload. ESA has therefore undertaken a study of the potential of using a 'ballistocraft', a small unmanned aircraft, to provide a low-cost facility for short-duration (30-40 seconds) microgravity experimentation. Fokker Space & Systems performed the study under an ESA contract, supported by Dutch national funding. To assess the ballistocraft, a simple breadboard of the facility was built and flight tests were performed. The ability of the on-board controller to achieve automated parabolic flights was demonstrated, and the performance of the controller in one-g level flights, and in flights with both zero-g and partial-g setpoints, was evaluated. The partial-g flights are a unique and valuable feature of the facility.

Performance of a Heating Block System Designed for Studying the Heat Resistance of Bacteria in Foods

NASA Astrophysics Data System (ADS)

Kou, Xiao-Xi; Li, Rui; Hou, Li-Xia; Huang, Zhi; Ling, Bo; Wang, Shao-Jin

2016-07-01

Knowledge of bacteria’s heat resistance is essential for developing effective thermal treatments. Choosing an appropriate test method is important to accurately determine bacteria’s heat resistances. Although being a major factor to influence the thermo-tolerance of bacteria, the heating rate in samples cannot be controlled in water or oil bath methods due to main dependence on sample’s thermal properties. A heating block system (HBS) was designed to regulate the heating rates in liquid, semi-solid and solid foods using a temperature controller. Distilled water, apple juice, mashed potato, almond powder and beef were selected to evaluate the HBS’s performance by experiment and computer simulation. The results showed that the heating rates of 1, 5 and 10 °C/min with final set-point temperatures and holding times could be easily and precisely achieved in five selected food materials. A good agreement in sample central temperature profiles was obtained under various heating rates between experiment and simulation. The experimental and simulated results showed that the HBS could provide a sufficiently uniform heating environment in food samples. The effect of heating rate on bacterial thermal resistance was evaluated with the HBS. The system may hold potential applications for rapid and accurate assessments of bacteria’s thermo-tolerances.

Sex hormone effects on autonomic mechanisms of thermoregulation in humans.

PubMed

Charkoudian, Nisha; Stachenfeld, Nina

2016-04-01

Autonomic mechanisms are fundamental to human physiological thermoregulation, and female reproductive hormones have substantial influences on several aspects of these mechanisms. Of these, the best recognized are the thermoregulatory responses that occur at menopause (hot flushes) and the changes in body temperature within the menstrual cycle which may help couples predict ovulation. Our goal in this brief review is to summarize current knowledge regarding the influences of reproductive hormones on autonomic mechanisms in human thermoregulation. In general, estrogens tend to promote lower body temperatures via augmentation of heat dissipation responses, whereas progesterone tends to promote higher body temperatures. Recent evidence suggests specific influences of estrogens on central autonomic nuclei involved in control of skin blood flow and sweating. Estrogens also augment vasodilation by direct effects on peripheral blood vessels. Influences of progesterone are less well understood, but include both centrally regulated changes in thermoregulatory set-point as well as and peripheral effects, including augmented vasoconstriction in the skin. We conclude with a brief discussion of thermoregulatory adjustments associated with changing hormone levels during menopause, pregnancy and polycystic ovary syndrome. Published by Elsevier B.V.

Predicting lettuce canopy photosynthesis with statistical and neural network models

NASA Technical Reports Server (NTRS)

Frick, J.; Precetti, C.; Mitchell, C. A.

1998-01-01

An artificial neural network (NN) and a statistical regression model were developed to predict canopy photosynthetic rates (Pn) for 'Waldman's Green' leaf lettuce (Latuca sativa L.). All data used to develop and test the models were collected for crop stands grown hydroponically and under controlled-environment conditions. In the NN and regression models, canopy Pn was predicted as a function of three independent variables: shootzone CO2 concentration (600 to 1500 micromoles mol-1), photosynthetic photon flux (PPF) (600 to 1100 micromoles m-2 s-1), and canopy age (10 to 20 days after planting). The models were used to determine the combinations of CO2 and PPF setpoints required each day to maintain maximum canopy Pn. The statistical model (a third-order polynomial) predicted Pn more accurately than the simple NN (a three-layer, fully connected net). Over an 11-day validation period, average percent difference between predicted and actual Pn was 12.3% and 24.6% for the statistical and NN models, respectively. Both models lost considerable accuracy when used to determine relatively long-range Pn predictions (> or = 6 days into the future).

Crosstalk of clock gene expression and autophagy in aging

PubMed Central

Kalfalah, Faiza; Janke, Linda; Schiavi, Alfonso; Tigges, Julia; Ix, Alexander; Ventura, Natascia; Boege, Fritz; Reinke, Hans

2016-01-01

Autophagy and the circadian clock counteract tissue degeneration and support longevity in many organisms. Accumulating evidence indicates that aging compromises both the circadian clock and autophagy but the mechanisms involved are unknown. Here we show that the expression levels of transcriptional repressor components of the circadian oscillator, most prominently the human Period homologue PER2, are strongly reduced in primary dermal fibroblasts from aged humans, while raising the expression of PER2 in the same cells partially restores diminished autophagy levels. The link between clock gene expression and autophagy is corroborated by the finding that the circadian clock drives cell-autonomous, rhythmic autophagy levels in immortalized murine fibroblasts, and that siRNA-mediated downregulation of PER2 decreases autophagy levels while leaving core clock oscillations intact. Moreover, the Period homologue lin-42 regulates autophagy and life span in the nematode Caenorhabditis elegans, suggesting an evolutionarily conserved role for Period proteins in autophagy control and aging. Taken together, this study identifies circadian clock proteins as set-point regulators of autophagy and puts forward a model, in which age-related changes of clock gene expression promote declining autophagy levels. PMID:27574892

Crosstalk of clock gene expression and autophagy in aging.

PubMed

Kalfalah, Faiza; Janke, Linda; Schiavi, Alfonso; Tigges, Julia; Ix, Alexander; Ventura, Natascia; Boege, Fritz; Reinke, Hans

2016-08-28

Autophagy and the circadian clock counteract tissue degeneration and support longevity in many organisms. Accumulating evidence indicates that aging compromises both the circadian clock and autophagy but the mechanisms involved are unknown. Here we show that the expression levels of transcriptional repressor components of the circadian oscillator, most prominently the human Period homologue PER2 , are strongly reduced in primary dermal fibroblasts from aged humans, while raising the expression of PER2 in the same cells partially restores diminished autophagy levels. The link between clock gene expression and autophagy is corroborated by the finding that the circadian clock drives cell-autonomous, rhythmic autophagy levels in immortalized murine fibroblasts, and that siRNA-mediated downregulation of PER2 decreases autophagy levels while leaving core clock oscillations intact. Moreover, the Period homologue lin-42 regulates autophagy and life span in the nematode Caenorhabditis elegans , suggesting an evolutionarily conserved role for Period proteins in autophagy control and aging. Taken together, this study identifies circadian clock proteins as set-point regulators of autophagy and puts forward a model, in which age-related changes of clock gene expression promote declining autophagy levels.

Line-of-sight pointing accuracy/stability analysis and computer simulation for small spacecraft

NASA Astrophysics Data System (ADS)

Algrain, Marcelo C.; Powers, Richard M.

1996-06-01

This paper presents a case study where a comprehensive computer simulation is developed to determine the driving factors contributing to spacecraft pointing accuracy and stability. The simulation is implemented using XMATH/SystemBuild software from Integrated Systems, Inc. The paper is written in a tutorial manner and models for major system components are described. Among them are spacecraft bus, attitude controller, reaction wheel assembly, star-tracker unit, inertial reference unit, and gyro drift estimators (Kalman filter). THe predicted spacecraft performance is analyzed for a variety of input commands and system disturbances. The primary deterministic inputs are desired attitude angles and rate setpoints. The stochastic inputs include random torque disturbances acting on the spacecraft, random gyro bias noise, gyro random walk, and star-tracker noise. These inputs are varied over a wide range to determine their effects on pointing accuracy and stability. The results are presented in the form of trade-off curves designed to facilitate the proper selection of subsystems so that overall spacecraft pointing accuracy and stability requirements are met.

Vascular remodeling: A redox-modulated mechanism of vessel caliber regulation.

PubMed

Tanaka, Leonardo Y; Laurindo, Francisco R M

2017-08-01

Vascular remodeling, i.e. whole-vessel structural reshaping, determines lumen caliber in (patho)physiology. Here we review mechanisms underlying vessel remodeling, with emphasis in redox regulation. First, we discuss confusing terminology and focus on strictu sensu remodeling. Second, we propose a mechanobiological remodeling paradigm based on the concept of tensional homeostasis as a setpoint regulator. We first focus on shear-mediated models as prototypes of remodeling closely dominated by highly redox-sensitive endothelial function. More detailed discussions focus on mechanosensors, integrins, extracellular matrix, cytoskeleton and inflammatory pathways as potential of mechanisms potentially coupling tensional homeostasis to redox regulation. Further discussion of remodeling associated with atherosclerosis and injury repair highlights important aspects of redox vascular responses. While neointima formation has not shown consistent responsiveness to antioxidants, vessel remodeling has been more clearly responsive, indicating that despite the multilevel redox signaling pathways, there is a coordinated response of the whole vessel. Among mechanisms that may orchestrate redox pathways, we discuss roles of superoxide dismutase activity and extracellular protein disulfide isomerase. We then discuss redox modulation of aneurysms, a special case of expansive remodeling. We propose that the redox modulation of vascular remodeling may reflect (1) remodeling pathophysiology is dominated by a particularly redox-sensitive cell type, e.g., endothelial cells (2) redox pathways are temporospatially coordinated at an organ level across distinct cellular and acellular structures or (3) the tensional homeostasis setpoint is closely connected to redox signaling. The mechanobiological/redox model discussed here can be a basis for improved understanding of remodeling and helps clarifying mechanisms underlying prevalent hard-to-treat diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

AIDS vaccines and preexposure prophylaxis: is synergy possible?

PubMed

Excler, Jean-Louis; Rida, Wasima; Priddy, Frances; Gilmour, Jill; McDermott, Adrian B; Kamali, Anatoli; Anzala, Omu; Mutua, Gaudensia; Sanders, Eduard J; Koff, Wayne; Berkley, Seth; Fast, Patricia

2011-06-01

While the long-term goal is to develop highly effective AIDS vaccines, first generation vaccines may be only partially effective. Other HIV prevention modalities such as preexposure prophylaxis with antiretrovirals (PrEP) may have limited efficacy as well. The combined administration of vaccine and PrEP (VAXPREP), however, may have a synergistic effect leading to an overall benefit that is greater than the sum of the individual effects. We propose two test-of-concept trial designs for an AIDS vaccine plus oral or topical ARV. In one design, evidence that PrEP reduces the risk of HIV acquisition is assumed to justify offering it to all participants. A two-arm study comparing PrEP alone to VAXPREP is proposed in which 30 to 60 incident infections are observed to assess the additional benefit of vaccination on risk of infection and setpoint viral load. The demonstrated superiority of VAXPREP does not imply vaccine alone is efficacious. Similarly, the lack of superiority does not imply vaccine alone is ineffective, as antagonism could exist between vaccine and PrEP. In the other design, PrEP is assumed not to be in general use. A 2 × 2 factorial design is proposed in which high-risk individuals are randomized to one of four arms: placebo vaccine given with placebo PrEP, placebo vaccine given with PrEP, vaccine given with placebo PrEP, or VAXPREP. Between 60 and 210 infections are required to detect a benefit of vaccination with or without PrEP on risk of HIV acquisition or setpoint viral load, with fewer infections needed when synergy is present.

Predictive Trip Detection for Nuclear Power Plants

NASA Astrophysics Data System (ADS)

Rankin, Drew J.; Jiang, Jin

2016-08-01

This paper investigates the use of a Kalman filter (KF) to predict, within the shutdown system (SDS) of a nuclear power plant (NPP), whether safety parameter measurements have reached a trip set-point. In addition, least squares (LS) estimation compensates for prediction error due to system-model mismatch. The motivation behind predictive shutdown is to reduce the amount of time between the occurrence of a fault or failure and the time of trip detection, referred to as time-to-trip. These reductions in time-to-trip can ultimately lead to increases in safety and productivity margins. The proposed predictive SDS differs from conventional SDSs in that it compares point-predictions of the measurements, rather than sensor measurements, against trip set-points. The predictive SDS is validated through simulation and experiments for the steam generator water level safety parameter. Performance of the proposed predictive SDS is compared against benchmark conventional SDS with respect to time-to-trip. In addition, this paper analyzes: prediction uncertainty, as well as; the conditions under which it is possible to achieve reduced time-to-trip. Simulation results demonstrate that on average the predictive SDS reduces time-to-trip by an amount of time equal to the length of the prediction horizon and that the distribution of times-to-trip is approximately Gaussian. Experimental results reveal that a reduced time-to-trip can be achieved in a real-world system with unknown system-model mismatch and that the predictive SDS can be implemented with a scan time of under 100ms. Thus, this paper is a proof of concept for KF/LS-based predictive trip detection.

Temperature and food mediate long-term thermotactic behavioral plasticity by association-independent mechanisms in C. elegans.

PubMed

Chi, Cynthia A; Clark, Damon A; Lee, Stella; Biron, David; Luo, Linjiao; Gabel, Christopher V; Brown, Jeffrey; Sengupta, Piali; Samuel, Aravinthan D T

2007-11-01

Thermotactic behavior in the nematode Caenorhabditis elegans exhibits long-term plasticity. On a spatial thermal gradient, C. elegans tracks isotherms near a remembered set-point (T(S)) corresponding to its previous cultivation temperature. When navigating at temperatures above its set-point (T>T(S)), C. elegans crawls down spatial thermal gradients towards the T(S) in what is called cryophilic movement. The T(S) retains plasticity in the adult stage and is reset by approximately 4 h of sustained exposure to a new temperature. Long-term plasticity in C. elegans thermotactic behavior has been proposed to represent an associative learning of specific temperatures conditioned in the presence or absence of bacterial food. Here, we use quantitative behavioral assays to define the temperature and food-dependent determinants of long-term plasticity in the different modes of thermotactic behavior. Under our experimental conditions, we find that starvation at a specific temperature neither disrupts T(S) resetting toward the starvation temperature nor induces learned avoidance of the starvation temperature. We find that prolonged starvation suppresses the cryophilic mode of thermotactic behavior. The hen-1 and tax-6 genes have been reported to affect associative learning between temperature and food-dependent cues. Under our experimental conditions, mutation in the hen-1 gene, which encodes a secreted protein with an LDL receptor motif, does not significantly affect thermotactic behavior or long-term plasticity. Mutation in the tax-6 calcineurin gene abolishes thermotactic behavior altogether. In summary, we do not find evidence that long-term plasticity requires association between temperature and the presence or absence of bacterial food.

mGluR7 genetics and alcohol: intersection yields clues for addiction.

PubMed

Gyetvai, Beatrix; Simonyi, Agnes; Oros, Melinda; Saito, Mariko; Smiley, John; Vadász, Csaba

2011-06-01

Development of addiction to alcohol or other substances can be attributed in part to exposure-dependent modifications at synaptic efficacy leading to an organism which functions at an altered homeostatic setpoint. Genetic factors may also influence setpoints and the stability of the homeostatic system of an organism. Quantitative genetic analysis of voluntary alcohol drinking, and mapping of the involved genes in the quasi-congenic Recombinant QTL Introgression strain system, identified Eac2 as a Quantitative Trait Locus (QTL) on mouse chromosome 6 which explained 18% of the variance with an effect size of 2.09 g/kg/day alcohol consumption, and Grm7 as a quantitative trait gene underlying Eac2 [Vadasz et al. in Neurochem Res 32:1099-1112, 100, Genomics 90:690-702, 102]. In earlier studies, the product of Grm7 mGluR7, a G protein-coupled receptor, has been implicated in stress systems [Mitsukawa et al. in Proc Natl Acad Sci USA 102:18712-18717, 63], anxiety-like behaviors [Cryan et al. in Eur J Neurosci 17:2409-2417, 14], memory [Holscher et al. in Learn Mem 12:450-455, 26], and psychiatric disorders (e.g., [Mick et al. in Am J Med Genet B Neuropsychiatr Genet 147B:1412-1418, 61; Ohtsuki et al. in Schizophr Res 101:9-16, 72; Pergadia et al. in Paper presented at the 38th Annual Meeting of the Behavior Genetics Association, Louisville, Kentucky, USA, 76]. Here, in experiments with mice, we show that (1) Grm7 knockout mice express increased alcohol consumption, (2) sub-congenic, and congenic mice carrying a Grm7 variant characterized by higher Grm7 mRNA drink less alcohol, and show a tendency for higher circadian dark phase motor activity in a wheel running paradigm, respectively, and (3) there are significant genetic differences in Grm7 mRNA abundance in the mouse brain between congenic and background mice identifying brain areas whose function is implicated in addiction related processes. We hypothesize that metabotropic glutamate receptors may function as regulators of homeostasis, and Grm7 (mGluR7) is involved in multiple processes (including stress, circadian activity, reward control, memory, etc.) which interact with substance use and the development of addiction. In conclusion, we suggest that mGluR7 is a significant new therapeutic target in addiction and related neurobehavioral disorders.

The evolution of subtype B HIV-1 tat in the Netherlands during 1985-2012.

PubMed

van der Kuyl, Antoinette C; Vink, Monique; Zorgdrager, Fokla; Bakker, Margreet; Wymant, Chris; Hall, Matthew; Gall, Astrid; Blanquart, François; Berkhout, Ben; Fraser, Christophe; Cornelissen, Marion

2018-05-02

For the production of viral genomic RNA, HIV-1 is dependent on an early viral protein, Tat, which is required for high-level transcription. The quantity of viral RNA detectable in blood of HIV-1 infected individuals varies dramatically, and a factor involved could be the efficiency of Tat protein variants to stimulate RNA transcription. HIV-1 virulence, measured by set-point viral load, has been observed to increase over time in the Netherlands and elsewhere. Investigation of tat gene evolution in clinical isolates could discover a role of Tat in this changing virulence. A dataset of 291 Dutch HIV-1 subtype B tat genes, derived from full-length HIV-1 genome sequences from samples obtained between 1985-2012, was used to analyse the evolution of Tat. Twenty-two patient-derived tat genes, and the control Tat HXB2 were analysed for their capacity to stimulate expression of an LTR-luciferase reporter gene construct in diverse cell lines, as well as for their ability to complement a tat-defective HIV-1 LAI clone. Analysis of 291 historical tat sequences from the Netherlands showed ample amino acid (aa) variation between isolates, although no specific mutations were selected for over time. Of note, however, the encoded protein varied its length over the years through the loss or gain of stop codons in the second exon. In transmission clusters, a selection against the shorter Tat86 ORF was apparent in favour of the more common Tat101 version, likely due to negative selection against Tat86 itself, although random drift, transmission bottlenecks, or linkage to other variants could also explain the observation. There was no correlation between Tat length and set-point viral load; however, the number of non-intermediate variants in our study was small. In addition, variation in the length of Tat did not significantly change its capacity to stimulate transcription. From 1985 till 2012, variation in the length of the HIV-1 subtype B tat gene is increasingly found in the Dutch epidemic. However, as Tat proteins did not differ significantly in their capacity to stimulate transcription elongation in vitro, the increased HIV-1 virulence seen in recent years could not be linked to an evolving viral Tat protein. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Efficient multi-scenario Model Predictive Control for water resources management with ensemble streamflow forecasts

NASA Astrophysics Data System (ADS)

Tian, Xin; Negenborn, Rudy R.; van Overloop, Peter-Jules; María Maestre, José; Sadowska, Anna; van de Giesen, Nick

2017-11-01

Model Predictive Control (MPC) is one of the most advanced real-time control techniques that has been widely applied to Water Resources Management (WRM). MPC can manage the water system in a holistic manner and has a flexible structure to incorporate specific elements, such as setpoints and constraints. Therefore, MPC has shown its versatile performance in many branches of WRM. Nonetheless, with the in-depth understanding of stochastic hydrology in recent studies, MPC also faces the challenge of how to cope with hydrological uncertainty in its decision-making process. A possible way to embed the uncertainty is to generate an Ensemble Forecast (EF) of hydrological variables, rather than a deterministic one. The combination of MPC and EF results in a more comprehensive approach: Multi-scenario MPC (MS-MPC). In this study, we will first assess the model performance of MS-MPC, considering an ensemble streamflow forecast. Noticeably, the computational inefficiency may be a critical obstacle that hinders applicability of MS-MPC. In fact, with more scenarios taken into account, the computational burden of solving an optimization problem in MS-MPC accordingly increases. To deal with this challenge, we propose the Adaptive Control Resolution (ACR) approach as a computationally efficient scheme to practically reduce the number of control variables in MS-MPC. In brief, the ACR approach uses a mixed-resolution control time step from the near future to the distant future. The ACR-MPC approach is tested on a real-world case study: an integrated flood control and navigation problem in the North Sea Canal of the Netherlands. Such an approach reduces the computation time by 18% and up in our case study. At the same time, the model performance of ACR-MPC remains close to that of conventional MPC.

A global bioheat model with self-tuning optimal regulation of body temperature using Hebbian feedback covariance learning.

PubMed

Ong, M L; Ng, E Y K

2005-12-01

In the lower brain, body temperature is continually being regulated almost flawlessly despite huge fluctuations in ambient and physiological conditions that constantly threaten the well-being of the body. The underlying control problem defining thermal homeostasis is one of great enormity: Many systems and sub-systems are involved in temperature regulation and physiological processes are intrinsically complex and intertwined. Thus the defining control system has to take into account the complications of nonlinearities, system uncertainties, delayed feedback loops as well as internal and external disturbances. In this paper, we propose a self-tuning adaptive thermal controller based upon Hebbian feedback covariance learning where the system is to be regulated continually to best suit its environment. This hypothesis is supported in part by postulations of the presence of adaptive optimization behavior in biological systems of certain organisms which face limited resources vital for survival. We demonstrate the use of Hebbian feedback covariance learning as a possible self-adaptive controller in body temperature regulation. The model postulates an important role of Hebbian covariance adaptation as a means of reinforcement learning in the thermal controller. The passive system is based on a simplified 2-node core and shell representation of the body, where global responses are captured. Model predictions are consistent with observed thermoregulatory responses to conditions of exercise and rest, and heat and cold stress. An important implication of the model is that optimal physiological behaviors arising from self-tuning adaptive regulation in the thermal controller may be responsible for the departure from homeostasis in abnormal states, e.g., fever. This was previously unexplained using the conventional "set-point" control theory.

Real-time Control of sewer pumps by using ControlNEXT to smooth inflow at Waste Water Treatment Plant Garmerwolde

NASA Astrophysics Data System (ADS)

van Heeringen, Klaas-Jan; van Nooijen, Ronald; Kooij, Kees; Postma, Bokke

2016-04-01

The Garmerwolde waste water treatment plant (WWTP) in the Groningen area of the Netherlands, receives waste water from a large area. That waste water is collected from many sewer systems and transported to the WWTP through pressurized pipes. The supply of waste water to the WWTP is relatively low and very irregular during dry-weather conditions, resulting in a random pattern of flows. This irregularity is the effect of the local control of the pumps, where the pumps are individually operated as an on/off control based on the water levels in the connected sewer system. The influent may change from zero to high values in a few minutes. The treatment processes at the WWTP are negatively influenced by this irregularity, which ends in high costs for energy and use of chemicals. The ControlNEXT central control system is used to control the 5 largest pump stations, such that the total inflow at the WWTP becomes much smoother. This results in a reduction of operational costs of about 10%. The control algorithm determines whether the actual condition is dry or wet, based on real-time radar precipitation images and the rainfall forecast product HiRLAM. All actual data is also collected and validated, like water levels, pump operations and pump availability. This data management is done using Delft-FEWS. If the situation is identified as "wet", the sewer systems are emptied as far as possible to create maximum storage. If the situation is "dry" (and of course there is a dead band between dry and wet), the pumps are operated such that the total inflow into the WWTP is smoothed. This is done with a Greedy algorithm, developed by Delft University of Technology. The algorithm makes a plan for the next 24 hours (as the daily inflow has a typical daily pattern) and generally stores some water volume in the sewer systems during the day to be able to continue operations during the night. The pumps are controlled with a time step of 5 minutes, where ControlNEXT manages the communication of pump operation setpoints to the SCADA system. In case of failing communication, backup procedures are programmed in the PLC of the pump stations. In that case the old on/off operation based on local water levels will be used. The system has been operational since January 2016 and has been monitored since then. In addition to monitoring the positive effect on the inflow at the WWTP, an important issue is the possible sedimentation in the sewer systems. This will be monitored too.

Distributed Smart Grid Asset Control Strategies for Providing Ancillary Services

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalsi, Karanjit; Zhang, Wei; Lian, Jianming

2013-10-30

With large-scale plans to integrate renewable generation driven mainly by state-level renewable portfolio requirements, more resources will be needed to compensate for the uncertainty and variability associated with intermittent generation resources. Distributed assets can be used to mitigate the concerns associated with renewable energy resources and to keep costs down. Under such conditions, performing primary frequency control using only supply-side resources becomes not only prohibitively expensive but also technically difficult. It is therefore important to explore how a sufficient proportion of the loads could assume a routine role in primary frequency control to maintain the stability of the system atmore » an acceptable cost. The main objective of this project is to develop a novel hierarchical distributed framework for frequency based load control. The framework involves two decision layers. The top decision layer determines the optimal gain for aggregated loads for each load bus. The gains are computed using decentralized robust control methods, and will be broadcast to the corresponding participating loads every control period. The second layer consists of a large number of heterogeneous devices, which switch probabilistically during contingencies so that aggregated power change matches the desired amount according to the most recently received gains. The simulation results show great potential to enable systematic design of demand-side primary frequency control with stability guarantees on the overall power system. The proposed design systematically accounts for the interactions between the total load response and bulk power system frequency dynamics. It also guarantees frequency stability under a wide range of time varying operating conditions. The local device-level load response rules fully respect the device constraints (such as temperature setpoint, compressor time delays of HVACs, or arrival and departure of the deferrable loads), which are crucial for implementing real load control programs. The promise of autonomous, Grid Friendly™ response by smart appliances in the form of under-frequency load shedding was demonstrated in the GridWise Olympic Peninsula Demonstration in 2006. Each controller monitored the power grid voltage signal and requested that electrical load be shed by its appliance whenever electric power-grid frequency fell below 59.95 Hz. The controllers and their appliances responded reliably to each shallow under-frequency event, which was an average of one event per day and shed their loads for the durations of these events. Another objective of this project was to perform extensive simulation studies to investigate the impact of a population of Grid Friendly™ Appliances (GFAs) on the bulk power system frequency stability. The GFAs considered in this report are represented as demonstration units with water heaters individually modeled.« less

Servo-control for maintaining abdominal skin temperature at 36C in low birth weight infants.

PubMed

Sinclair, J C

2000-01-01

Randomized trials have shown that the neonatal mortality rate of low birth-weight babies can be reduced by keeping them warm. For low birth-weight babies nursed in incubators, warm conditions may be achieved either by heating the air to a desired temperature, or by servo-controlling the baby's body temperature at a desired set-point. In low birth weight infants, to determine the effect on death and other important clinical outcomes of targeting body temperature rather than air temperature as the end-point of control of incubator heating. Standard search strategy of the Cochrane Neonatal Collaborative Review Group. Randomized or quasi-randomized trials which test the effects of having the heat output of the incubator servo-controlled from body temperature compared with setting a constant incubator air temperature. Trial methodologic quality was systematically assessed. Outcome measures included death, timing of death, cause of death, and other clinical outcomes. Categorical outcomes were analyzed using relative risk and risk difference. Meta-analysis assumed a fixed effect model. Compared to setting a constant incubator air temperature of 31.8C, servo-control of abdominal skin temperature at 36C reduces the neonatal death rate among low birth weight infants: relative risk 0.72 (95% CI 0.54, 0.97); risk difference -12.7% (95% CI -1.6, -23.9). This effect is even greater among VLBW infants. During at least the first week after birth, low birth weight babies should be provided with a carefully regulated thermal environment that is near the thermoneutral point. For LBW babies in incubators, this can be achieved by adjusting incubator temperature to maintain an anterior abdominal skin temperature of at least 36C, using either servo-control or frequent manual adjustment of incubator air temperature.

Bio-inspired control of joint torque and knee stiffness in a robotic lower limb exoskeleton using a central pattern generator.

PubMed

Schrade, Stefan O; Nager, Yannik; Wu, Amy R; Gassert, Roger; Ijspeert, Auke

2017-07-01

Robotic lower limb exoskeletons are becoming increasingly popular in therapy and recreational use. However, most exoskeletons are still rather limited in their locomotion speed and the activities of daily live they can perform. Furthermore, they typically do not allow for a dynamic adaptation to the environment, as they are often controlled with predefined reference trajectories. Inspired by human leg stiffness modulation during walking, variable stiffness actuators increase flexibility without the need for more complex controllers. Actuation with adaptable stiffness is inspired by the human leg stiffness modulation during walking. However, this actuation principle also introduces the stiffness setpoint as an additional degree of freedom that needs to be coordinated with the joint trajectories. As a potential solution to this issue a bio-inspired controller based on a central pattern generator (CPG) is presented in this work. It generates coordinated joint torques and knee stiffness modulations to produce flexible and dynamic gait patterns for an exoskeleton with variable knee stiffness actuation. The CPG controller is evaluated and optimized in simulation using a model of the exoskeleton. The CPG controller produced stable and smooth gait for walking speeds from 0.4 m/s up to 1.57 m/s with a torso stabilizing force that simulated the use of crutches, which are commonly needed by exoskeleton users. Through the CPG, the knee stiffness intrinsically adapted to the frequency and phase of the gait, when the speed was changed. Additionally, it adjusted to changes in the environment in the form of uneven terrain by reacting to ground contact forces. This could allow future exoskeletons to be more adaptive to various environments, thus making ambulation more robust.

Decentralized Energy Management System for Networked Microgrids in Grid-connected and Islanded Modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhaoyu; Chen, Bokan; Wang, Jianhui

This paper proposes a decentralized energy management system (EMS) for the coordinated operation of networked Microgirds (MGs) in a distribution system. In the grid-connected mode, the distribution network operator (DNO) and each MG are considered as distinct entities with individual objectives to minimize their own operation costs. It is assumed that both dispatchable and renewable energy source (RES)-based distributed generators (DGs) exist in the distribution network and the networked MGs. In order to coordinate the operation of all entities, we apply a decentralized bi-level algorithm to solve the problem with the first level to conduct negotiations among all entities andmore » the second level to update the non-converging penalties. In the islanded mode, the objective of each MG is to maintain a reliable power supply to its customers. In order to take into account the uncertainties of DG outputs and load consumption, we formulate the problems as two-stage stochastic programs. The first stage is to determine base generation setpoints based on the forecasts and the second stage is to adjust the generation outputs based on the realized scenarios. Case studies of a distribution system with networked MGs demonstrate the effectiveness of the proposed methodology in both grid-connected and islanded modes.« less

A unified model of shoot tropism in plants: photo-, gravi- and Propio-ception.

PubMed

Bastien, Renaud; Douady, Stéphane; Moulia, Bruno

2015-02-01

Land plants rely mainly on gravitropism and phototropism to control their posture and spatial orientation. In natural conditions, these two major tropisms act concurrently to create a photogravitropic equilibrium in the responsive organ. Recently, a parsimonious model was developed that accurately predicted the complete gravitropic and proprioceptive control over the movement of different organs in different species in response to gravitational stimuli. Here we show that the framework of this unifying graviproprioceptive model can be readily extended to include phototropism. The interaction between gravitropism and phototropism results in an alignment of the apical part of the organ toward a photogravitropic set-point angle. This angle is determined by a combination of the two directional stimuli, gravity and light, weighted by the ratio between the gravi- and photo-sensitivities of the plant organ. In the model, two dimensionless numbers, the graviproprioceptive number B and the photograviceptive number M, control the dynamics and the shapes of the movement. The extended model agrees well with two sets of detailed quantitative data on photogravitropic equilibrium in oat coleoptiles. It is demonstrated that the influence of light intensity I can be included in the model in a power-law-dependent relationship M(I). The numbers B and M and the related photograviceptive number D are all quantitative genetic traits that can be measured in a straightforward manner, opening the way to the phenotyping of molecular and mechanical aspects of shoot tropism.

Effects of neonatal hyperthyroidism on the development of the hypothalamic-pituitary-thyroid axis in the rat.

PubMed

Dussault, J H; Coulombe, P; Walker, P

1982-03-01

The acute and latent effects of neonatal hyperthyroidism (NH) on the hypothalamic-pituitary-thyroid axis were studied in the rat after treatment of newborn animals with L-T4 (0.4 microgram/g BW, daily) for a period of 12 days. NH was associated with a permanent reduction in body weight in both male and female rats, in addition to a delay in the attainment of peak concentrations of hypothalamic TRH and pituitary and serum TSH. Serum TSH, T4, and T3 concentrations also were significantly and permanently reduced in NH animals (P less than 0.01) after cessation of L-T4 treatment. The serum TSH secretory response to 1 microgram synthetic TRH also was evaluated in 120-day-old control and NH rats, before and after the administration of L-T4 (0.6 microgram/100 g BW for 7 days) or propylthiouracil (0.05% in the drinking water for 14 days). In the baseline state, adult NH rats had a net secretory response similar to that of controls (189.0 +/- 31.3 vs. 227.0 +/- 29.3 microgram/ml . min). Administration of T4 significantly decreased while propylthiouracil treatment significantly increased the net TSH secretory response of NH rats compared to similarly treated control rats. These data are compatible with the hypothesis that NH leads to a permanent resetting of the regulatory set-point for pituitary TSH secretion and to increased sensitivity to the feedback inhibitory effects of thyroid hormones.

A Unified Model of Shoot Tropism in Plants: Photo-, Gravi- and Propio-ception

PubMed Central

Bastien, Renaud; Douady, Stéphane; Moulia, Bruno

2015-01-01

Land plants rely mainly on gravitropism and phototropism to control their posture and spatial orientation. In natural conditions, these two major tropisms act concurrently to create a photogravitropic equilibrium in the responsive organ. Recently, a parsimonious model was developed that accurately predicted the complete gravitropic and proprioceptive control over the movement of different organs in different species in response to gravitational stimuli. Here we show that the framework of this unifying graviproprioceptive model can be readily extended to include phototropism. The interaction between gravitropism and phototropism results in an alignment of the apical part of the organ toward a photogravitropic set-point angle. This angle is determined by a combination of the two directional stimuli, gravity and light, weighted by the ratio between the gravi- and photo-sensitivities of the plant organ. In the model, two dimensionless numbers, the graviproprioceptive number B and the photograviceptive number M, control the dynamics and the shapes of the movement. The extended model agrees well with two sets of detailed quantitative data on photogravitropic equilibrium in oat coleoptiles. It is demonstrated that the influence of light intensity I can be included in the model in a power-law-dependent relationship M(I). The numbers B and M and the related photograviceptive number D are all quantitative genetic traits that can be measured in a straightforward manner, opening the way to the phenotyping of molecular and mechanical aspects of shoot tropism. PMID:25692607

Vaccine-induced, simian immunodeficiency virus-specific CD8+ T cells reduce virus replication but do not protect from simian immunodeficiency virus disease progression.

PubMed

Engram, Jessica C; Dunham, Richard M; Makedonas, George; Vanderford, Thomas H; Sumpter, Beth; Klatt, Nichole R; Ratcliffe, Sarah J; Garg, Seema; Paiardini, Mirko; McQuoid, Monica; Altman, John D; Staprans, Silvija I; Betts, Michael R; Garber, David A; Feinberg, Mark B; Silvestri, Guido

2009-07-01

Our limited understanding of the interaction between primate lentiviruses and the host immune system complicates the design of an effective HIV/AIDS vaccine. To identify immunological correlates of protection from SIV disease progression, we immunized two groups of five rhesus macaques (RMs) with either modified vaccinia Ankara (MVA) or MVADeltaudg vectors that expressed SIVmac239 Gag and Tat. Both vectors raised a SIV-specific CD8(+) T cell response, with a magnitude that was greater in mucosal tissues than in peripheral blood. After challenge with SIVmac239, all vaccinated RMs showed mucosal and systemic CD8(+) T cell recall responses that appeared faster and were of greater magnitude than those in five unvaccinated control animals. All vaccinated RMs showed a approximately 1-log lower peak and early set-point SIV viral load than the unvaccinated animals, and then, by 8 wk postchallenge, exhibited levels of viremia similar to the controls. We observed a significant direct correlation between the magnitude of postchallenge SIV-specific CD8(+) T cell responses and SIV viral load. However, vaccinated RMs showed no protection from either systemic or mucosal CD4(+) T cell depletion and no improved survival. The observation that vaccine-induced, SIV-specific CD8(+) T cells that partially control SIVmac239 virus replication fail to protect from immunological or clinical progression of SIV infection underscores both the complexity of AIDS pathogenesis and the challenges of properly assessing the efficacy of candidate AIDS vaccines.

Immunologic and Virologic Mechanisms for Partial Protection from Intravenous Challenge by an Integration-Defective SIV Vaccine †

PubMed Central

Wang, Chu; Jiang, Chunlai; Gao, Nan; Zhang, Kaikai; Liu, Donglai; Wang, Wei; Cong, Zhe; Qin, Chuan; Ganusov, Vitaly V.; Ferrari, Guido; LaBranche, Celia; Montefiori, David C.; Kong, Wei; Yu, Xianghui; Gao, Feng

2017-01-01

The suppression of viral loads and identification of selection signatures in non-human primates after challenge are indicators for effective human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) vaccines. To mimic the protective immunity elicited by attenuated SIV vaccines, we developed an integration-defective SIV (idSIV) vaccine by inactivating integrase, mutating sequence motifs critical for integration, and inserting the cytomegalovirus (CMV) promoter for more efficient expression in the SIVmac239 genome. Chinese rhesus macaques were immunized with idSIV DNA and idSIV particles, and the cellular and humoral immune responses were measured. After the intravenous SIVmac239 challenge, viral loads were monitored and selection signatures in viral genomes from vaccinated monkeys were identified by single genome sequencing. T cell responses, heterologous neutralization against tier-1 viruses, and antibody-dependent cellular cytotoxicity (ADCC) were detected in idSIV-vaccinated macaques post immunization. After challenge, the median peak viral load in the vaccine group was significantly lower than that in the control group. However, this initial viral control did not last as viral set-points were similar between vaccinated and control animals. Selection signatures were identified in Nef, Gag, and Env proteins in vaccinated and control macaques, but these signatures were different, suggesting selection pressure on viruses from vaccine-induced immunity in the vaccinated animals. Our results showed that the idSIV vaccine exerted some pressure on the virus population early during the infection but future modifications are needed in order to induce more potent immune responses. PMID:28574482

Microgravity does not alter plant stand gas exchange of wheat at moderate light levels and saturating CO2 concentration.

PubMed

Monje, O; Stutte, G; Chapman, D

2005-10-01

Plant stand gas exchange was measured nondestructively in microgravity during the Photosynthesis Experiment Subsystem Testing and Operations experiment conducted onboard the International Space Station. Rates of evapotranspiration and photosynthesis measured in space were compared with ground controls to determine if microgravity directly affects whole-stand gas exchange of Triticum aestivum. During six 21-day experiment cycles, evapotranspiration was determined continuously from water addition rates to the nutrient delivery system, and photosynthesis was determined from the amount of CO2 added to maintain the chamber CO2 concentration setpoint. Plant stand evapotranspiration, net photosynthesis, and water use efficiency were not altered by microgravity. Although leaf area was significantly reduced in microgravity-grown plants compared to ground control plants, leaf area distribution was not affected enough to cause significant differences in the amounts of light absorbed by the flight and ground control plant stands. Microgravity also did not affect the response of evapotranspiration to changes in chamber vapor pressure difference of 12-day-old wheat plant stands. These results suggest that gravity naïve plants grown at moderate light levels (300 micromol m(-2) s(-1)) behave the same as ground control plants. This implies that future plant-based regenerative life support systems can be sized using 1 g data because water purification and food production rates operate at nearly the same rates as in 1 g at moderate light levels. However, it remains to be verified whether the present results are reproducible in plants grown under stronger light levels.

Energy-Efficient and Comfortable Buildings through Multivariate Integrated Control (ECoMIC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birru, Dagnachew; Wen, Yao-Jung; Rubinstein, Francis M.

2013-10-28

This project aims to develop an integrated control solution for enhanced energy efficiency and user comfort in commercial buildings. The developed technology is a zone-based control framework that minimizes energy usage while maintaining occupants’ visual and thermal comfort through control of electric lights, motorized venetian blinds and thermostats. The control framework is designed following a modular, scalable and flexible architecture to facilitate easy integration with exiting building management systems. The control framework contains two key algorithms: 1) the lighting load balancing algorithm and 2) the thermostat control algorithm. The lighting load balancing algorithm adopts a model-based closed-loop control approach tomore » determine the optimal electric light and venetian blind settings. It is formulated into an optimization problem with minimizing lighting-related energy consumptions as the objective and delivering adequate task light and preventing daylight glare as the constraints. The thermostat control algorithm is based on a well-established thermal comfort model and formulated as a root-finding problem to dynamically determine the optimal thermostat setpoint for both energy savings and improved thermal comfort. To address building-wide scalability, a system architecture was developed for the zone-based control technology. Three levels of services are defined in the architecture: external services, facility level services and zone level services. The zone-level service includes the control algorithms described above as well as the corresponding interfaces, profiles, sensors and actuators to realize the zone controller. The facility level services connect to the zones through a backbone network, handle supervisory level information and controls, and thus facilitate building-wide scalability. The external services provide communication capability to entities outside of the building for grid interaction and remote access. Various aspects of the developed control technology were evaluated and verified through both simulations and testbed implementations. Simulations coupling a DOE medium office reference building in EnergyPlus building simulation software and a prototype controller in Matlab were performed. During summer time in a mixed-humid climate zone, the simulations revealed reductions of 27% and 42% in electric lighting load and cooling load, respectively, when compared to an advanced base case with daylight dimming and blinds automatically tilted to block direct sun. Two single-room testbeds were established. The testbed at Philips Lighting business building (Rosemont, IL) was designed for quantifying energy performance of integrated controls. This particular implementation achieved 40% and 79% savings on lighting and HVAC energy, respectively, compared to a relatively simple base case operated on predefined schedules. While the resulting energy savings was very encouraging, it should be noted that there may be several caveats associated with it. 1) The test was run during late spring and early summer, and the savings numbers might not be directly used to extrapolate the annual energy savings. 2) Due to the needs for separate control and metering of the small-scale demonstrator within a large building, the HVAC system, hence the corresponding savings, did not represent a typical energy code-compliant design. 3) The light level in the control case was regulated at a particular setpoint, which was lower than then the full-on light level in the base case, and the savings resulted from tuning down the light level to the setpoint was not attributable to the contribution of the developed technology. The testbed at the Lawrence Berkeley National Laboratory (Berkeley, CA) specifically focused on glare control integration, and has demonstrated the feasibility and capability of the glare detection and prevention technique. While the short one-month test in this testbed provided a functional indication of the developed technology, and it would require at least a full solstice-to-solstice cycle to ruinously quantify the performance, which was not possible within the project timeframe. There are certain limitations inherited from the operational assumptions, which could potentially affect the effectiveness and applicability of the developed control technologies. The system takes a typical ceiling-mounting approach for the photosensor locations, and therefore, the control performance relies on proper commissioning or the built-in intelligence of the photosensor for pertinent task light level estimations. For spaces where daylight penetration diminishes significantly deeper into the zone, certain modification to the control algorithms is required to accommodate multiple lighting control subzones and the corresponding sensors for providing a more uniform light level across the entire zone. Integrated control of visual and thermal comfort requires the lighting control zone and thermal control zone to coincide with each other. In other words, the area illuminated by a lighting circuit needs to be the same area served by the thermostat. Thus, the original zoning will potentially constrain the applicability of this technology in retrofitting projects. This project demonstrated the technical feasibility of a zone-based integrated control technology. From the simulation results and testbed implementations, up to 60% lighting energy savings in daylit areas relative to a “no-controls” case can easily be achieved. A 20% reduction of whole building energy consumption is also attainable. In the aspect of occupant comfort, the testbed demonstrated the ability to maintain specified light level on the workplane while promptly mitigate daylight glare 90% of the time. The control system also managed to maintain the thermal environment at a comfortable level 90% of the time. The aspect of system scalability was guaranteed by the system architecture design, based on which the testbeds were instantiated. Analysis on the aspect of economic benefit has yielded an about 6-year payback time for a medium-sized building, including the installation of all hardware and software, such as motorized blinds and LED luminaires. The payback time can be significantly reduced if part of the hardware is already in place for retrofitting projects. It needs to be noted that since the payback analysis was partly based on the testbed performance results, it is constrained by the caveats associated with the testbed implementations. The main uncertainty lies in the contribution from the space conditioning energy savings as it was non-trivial to realistically configure a room-size HVAC system for directly extrapolating whole-building HVAC energy savings. It is recommended to further evaluate the developed technology at a larger scale, where the lighting and HVAC energy consumption can be realistically measured at the building level, to more rigorously quantify the performance potentials.« less

Seasonal thermoregulatory responses in mammals.

PubMed

Lovegrove, Barry G

2005-05-01

This study examined the proportional seasonal winter adjustments of total and mass-specific basal power (watts and watts g-1, respectively), thermal conductance (watts g-1 degrees C-1), non-shivering thermogenesis capacity (ratio of NST/basal power), body temperature ( degrees C), and body mass (g) of mammals. The responses are best summarized for three different body size classes; small mammals (<100 g), intermediate-sized mammals (0.1-10 kg), and large mammals (>10 kg). The principal adjustments of the small mammals center on energy conservation, especially the Dehnel Effect, the winter reduction in body size of as much as 50%, accompanied by reductions in mass-specific basal power. On average, these reductions reduce the total basal power approximately in direct proportion to the mass reductions. Reductions in mass-specific basal power are matched by concomitant reductions in conductance to maintain the setpoint body temperature during winter. The overall thermoregulatory adjustments in small mammals serve to (a) lower overall winter power consumption, (b) maintain the setpoint body temperature, and (c) lower the lower critical limit of thermoneutrality and hence thermoregulatory costs. In intermediate-size mammals, the seasonal response is centered more on increasing thermogenic capacity by increasing basal power and NST capacity, accompanied by predictable and large reductions in conductance. The Dehnel effect is negligible. Very large mammals undergo the largest reductions in total and mass-specific basal power and conductance. However, there are too few data to resolve whether the reductions in total basal power can be attributed to the Dehnel effect, because the moderate decreases in body mass may also be caused by nutritional stress. Apart from the seasonal changes in basal power, these observations are consistent with the predictions of Heldmaier's seasonal acclimatization model.

Resource Management in Constrained Dynamic Situations

NASA Astrophysics Data System (ADS)

Seok, Jinwoo

Resource management is considered in this dissertation for systems with limited resources, possibly combined with other system constraints, in unpredictably dynamic environments. Resources may represent fuel, power, capabilities, energy, and so on. Resource management is important for many practical systems; usually, resources are limited, and their use must be optimized. Furthermore, systems are often constrained, and constraints must be satisfied for safe operation. Simplistic resource management can result in poor use of resources and failure of the system. Furthermore, many real-world situations involve dynamic environments. Many traditional problems are formulated based on the assumptions of given probabilities or perfect knowledge of future events. However, in many cases, the future is completely unknown, and information on or probabilities about future events are not available. In other words, we operate in unpredictably dynamic situations. Thus, a method is needed to handle dynamic situations without knowledge of the future, but few formal methods have been developed to address them. Thus, the goal is to design resource management methods for constrained systems, with limited resources, in unpredictably dynamic environments. To this end, resource management is organized hierarchically into two levels: 1) planning, and 2) control. In the planning level, the set of tasks to be performed is scheduled based on limited resources to maximize resource usage in unpredictably dynamic environments. In the control level, the system controller is designed to follow the schedule by considering all the system constraints for safe and efficient operation. Consequently, this dissertation is mainly divided into two parts: 1) planning level design, based on finite state machines, and 2) control level methods, based on model predictive control. We define a recomposable restricted finite state machine to handle limited resource situations and unpredictably dynamic environments for the planning level. To obtain a policy, dynamic programing is applied, and to obtain a solution, limited breadth-first search is applied to the recomposable restricted finite state machine. A multi-function phased array radar resource management problem and an unmanned aerial vehicle patrolling problem are treated using recomposable restricted finite state machines. Then, we use model predictive control for the control level, because it allows constraint handling and setpoint tracking for the schedule. An aircraft power system management problem is treated that aims to develop an integrated control system for an aircraft gas turbine engine and electrical power system using rate-based model predictive control. Our results indicate that at the planning level, limited breadth-first search for recomposable restricted finite state machines generates good scheduling solutions in limited resource situations and unpredictably dynamic environments. The importance of cooperation in the planning level is also verified. At the control level, a rate-based model predictive controller allows good schedule tracking and safe operations. The importance of considering the system constraints and interactions between the subsystems is indicated. For the best resource management in constrained dynamic situations, the planning level and the control level need to be considered together.

A boundary PDE feedback control approach for the stabilization of mortgage price dynamics

NASA Astrophysics Data System (ADS)

Rigatos, G.; Siano, P.; Sarno, D.

2017-11-01

Several transactions taking place in financial markets are dependent on the pricing of mortgages (loans for the purchase of residences, land or farms). In this article, a method for stabilization of mortgage price dynamics is developed. It is considered that mortgage prices follow a PDE model which is equivalent to a multi-asset Black-Scholes PDE. Actually it is a diffusion process evolving in a 2D assets space, where the first asset is the house price and the second asset is the interest rate. By applying semi-discretization and a finite differences scheme this multi-asset PDE is transformed into a state-space model consisting of ordinary nonlinear differential equations. For the local subsystems, into which the mortgage PDE is decomposed, it becomes possible to apply boundary-based feedback control. The controller design proceeds by showing that the state-space model of the mortgage price PDE stands for a differentially flat system. Next, for each subsystem which is related to a nonlinear ODE, a virtual control input is computed, that can invert the subsystem's dynamics and can eliminate the subsystem's tracking error. From the last row of the state-space description, the control input (boundary condition) that is actually applied to the multi-factor mortgage price PDE system is found. This control input contains recursively all virtual control inputs which were computed for the individual ODE subsystems associated with the previous rows of the state-space equation. Thus, by tracing the rows of the state-space model backwards, at each iteration of the control algorithm, one can finally obtain the control input that should be applied to the mortgage price PDE system so as to assure that all its state variables will converge to the desirable setpoints. By showing the feasibility of such a control method it is also proven that through selected modification of the PDE boundary conditions the price of the mortgage can be made to converge and stabilize at specific reference values.

Water Phase Change Heat Exchanger System Level Analysis for Low Lunar Orbit

NASA Technical Reports Server (NTRS)

Navarro, Moses; Ungar, Eugene; Sheth, Rubik; Hansen, Scott

2016-01-01

In low Lunar orbit (LLO) the thermal environment is cyclic - extremely cold in the eclipse and as warm as room temperature near the subsolar point. Phase change material heat exchangers (PCHXs) are the best option for long term missions in these environments. The Orion spacecraft will use a n-pentadecane wax PCHX for its envisioned mission to LLO. Using water as a PCM material is attractive because its higher heat of fusion and greater density result in a lighter, more compact PCHX. To assess the use of a water PCHX for a human spacecraft in a circular LLO, a system level analysis was performed for the Orion spacecraft. Three cases were evaluated: 1) A one-to-one replacement of the wax PCHX on the internal thermal control loop with a water PCHX (including the appropriate control modifications), 2) reducing the radiator return setpoint temperature below Orion's value to enhance PCHX freezing, and 3) placing the water PCM on the external loop. The model showed that the water PCHX could not be used as a drop-in replacement for the wax PCHX. It did not freeze fully during the eclipse owing to its low freezing point. To obtain equivalent performance, 40% more radiator area than the Orion baseline was required. The study shows that, although water PCHXs are attractive at a component level, system level effects mean that they are not the best choice for LLO.

GNOCIS an update of the generic NO{sub x} control intelligent system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmes, R.; Mayes, I.; Irons, R.

1996-01-01

GNOCIS is an on-line enhancement to existing power plant Digital Control Systems (DCS) designed to reduce NO{sub x} emissions while meeting other operational constraints, such as heat rate and CO emissions. It can also be used to minimize unburned carbon while meeting a specified NO{sub x} limit, or any combination of emissions/performance variables that can be quantified by a common metric and are affected by DCS - adjustable parameters. The core of the system is an adaptive neural network model of the NO{sub x} generation characteristics of the boiler. The software applies an optimizing procedure to identify the best setpointsmore » for the plant. The recommended setpoints can be either conveyed to the operator via the DCS in an advisory mode, or implemented automatically in a closed-loop mode. GNOCIS is designed to run on a stand-alone workstation connected to the DCS via the data highway. Sensor validation techniques have been incorporated. The goal for GNOSIS is to deliver 10-35% reductions in NO{sub x} from baseline conditions while maintaining or improving other operational constraints. Preliminary results are presented for demonstrations at two power plants: (1) 500-MW T-fired boiler at PowerGen`s Kingsnorth Station, (2) 250-MW Opposed-fired boiler at Alabama Power Company`s Gaston Station.« less

Allostatic Self-efficacy: A Metacognitive Theory of Dyshomeostasis-Induced Fatigue and Depression.

PubMed

Stephan, Klaas E; Manjaly, Zina M; Mathys, Christoph D; Weber, Lilian A E; Paliwal, Saee; Gard, Tim; Tittgemeyer, Marc; Fleming, Stephen M; Haker, Helene; Seth, Anil K; Petzschner, Frederike H

2016-01-01

This paper outlines a hierarchical Bayesian framework for interoception, homeostatic/allostatic control, and meta-cognition that connects fatigue and depression to the experience of chronic dyshomeostasis. Specifically, viewing interoception as the inversion of a generative model of viscerosensory inputs allows for a formal definition of dyshomeostasis (as chronically enhanced surprise about bodily signals, or, equivalently, low evidence for the brain's model of bodily states) and allostasis (as a change in prior beliefs or predictions which define setpoints for homeostatic reflex arcs). Critically, we propose that the performance of interoceptive-allostatic circuitry is monitored by a metacognitive layer that updates beliefs about the brain's capacity to successfully regulate bodily states (allostatic self-efficacy). In this framework, fatigue and depression can be understood as sequential responses to the interoceptive experience of dyshomeostasis and the ensuing metacognitive diagnosis of low allostatic self-efficacy. While fatigue might represent an early response with adaptive value (cf. sickness behavior), the experience of chronic dyshomeostasis may trigger a generalized belief of low self-efficacy and lack of control (cf. learned helplessness), resulting in depression. This perspective implies alternative pathophysiological mechanisms that are reflected by differential abnormalities in the effective connectivity of circuits for interoception and allostasis. We discuss suitably extended models of effective connectivity that could distinguish these connectivity patterns in individual patients and may help inform differential diagnosis of fatigue and depression in the future.

Allostatic Self-efficacy: A Metacognitive Theory of Dyshomeostasis-Induced Fatigue and Depression

PubMed Central

Stephan, Klaas E.; Manjaly, Zina M.; Mathys, Christoph D.; Weber, Lilian A. E.; Paliwal, Saee; Gard, Tim; Tittgemeyer, Marc; Fleming, Stephen M.; Haker, Helene; Seth, Anil K.; Petzschner, Frederike H.

2016-01-01

This paper outlines a hierarchical Bayesian framework for interoception, homeostatic/allostatic control, and meta-cognition that connects fatigue and depression to the experience of chronic dyshomeostasis. Specifically, viewing interoception as the inversion of a generative model of viscerosensory inputs allows for a formal definition of dyshomeostasis (as chronically enhanced surprise about bodily signals, or, equivalently, low evidence for the brain's model of bodily states) and allostasis (as a change in prior beliefs or predictions which define setpoints for homeostatic reflex arcs). Critically, we propose that the performance of interoceptive-allostatic circuitry is monitored by a metacognitive layer that updates beliefs about the brain's capacity to successfully regulate bodily states (allostatic self-efficacy). In this framework, fatigue and depression can be understood as sequential responses to the interoceptive experience of dyshomeostasis and the ensuing metacognitive diagnosis of low allostatic self-efficacy. While fatigue might represent an early response with adaptive value (cf. sickness behavior), the experience of chronic dyshomeostasis may trigger a generalized belief of low self-efficacy and lack of control (cf. learned helplessness), resulting in depression. This perspective implies alternative pathophysiological mechanisms that are reflected by differential abnormalities in the effective connectivity of circuits for interoception and allostasis. We discuss suitably extended models of effective connectivity that could distinguish these connectivity patterns in individual patients and may help inform differential diagnosis of fatigue and depression in the future. PMID:27895566

FIRST BEAM TESTS OF THE APS MBA UPGRADE ORBIT FEEDBACK CONTROLLER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sereno, N. S.; Arnold, N.; Brill, A.

The new orbit feedback system required for the APS multi-bend acromat (MBA) ring must meet challenging beam stability requirements. The AC stability requirement is to correct rms beam motion to 10 % the rms beam size at the insertion device source points from 0.01 to 1000 Hz. The vertical plane represents the biggest challenge for AC stability which is required to be 400 nm rms for a 4 micron vertical beam size. In addition long term drift over a period of 7 days is required to be 1 micron or less at insertion de- vice BPMs and 2 microns formore » arc bpms. We present test re- sults of theMBA prototype orbit feedback controller (FBC) in the APS storage ring. In this test, four insertion device BPMs were configured to send data to the FBC for process- ing into four fast corrector setpoints. The configuration of four bpms and four fast correctors creates a 4-bump and the configuration of fast correctors is similar to what will be implemented in the MBA ring. We report on performance benefits of increasing the sampling rate by a factor of 15 to 22.6 kHz over the existing APS orbit feedback system, lim- itations due to existing storage ring hardware and extrapo- lation to theMBA orbit feedback design. FBC architecture, signal flow and processing design will also be discussed.« less

Atomic force microscopy imaging of macromolecular complexes.

PubMed

Santos, Sergio; Billingsley, Daniel; Thomson, Neil

2013-01-01

This chapter reviews amplitude modulation (AM) AFM in air and its applications to high-resolution imaging and interpretation of macromolecular complexes. We discuss single DNA molecular imaging and DNA-protein interactions, such as those with topoisomerases and RNA polymerase. We show how relative humidity can have a major influence on resolution and contrast and how it can also affect conformational switching of supercoiled DNA. Four regimes of AFM tip-sample interaction in air are defined and described, and relate to water perturbation and/or intermittent mechanical contact of the tip with either the molecular sample or the surface. Precise control and understanding of the AFM operational parameters is shown to allow the user to switch between these different regimes: an interpretation of the origins of topographical contrast is given for each regime. Perpetual water contact is shown to lead to a high-resolution mode of operation, which we term SASS (small amplitude small set-point) imaging, and which maximizes resolution while greatly decreasing tip and sample wear and any noise due to perturbation of the surface water. Thus, this chapter provides sufficient information to reliably control the AFM in the AM AFM mode of operation in order to image both heterogeneous samples and single macromolecules including complexes, with high resolution and with reproducibility. A brief introduction to AFM, its versatility and applications to biology is also given while providing references to key work and general reviews in the field.

Continuous Modeling of Calcium Transport Through Biological Membranes

NASA Astrophysics Data System (ADS)

Jasielec, J. J.; Filipek, R.; Szyszkiewicz, K.; Sokalski, T.; Lewenstam, A.

2016-08-01

In this work an approach to the modeling of the biological membranes where a membrane is treated as a continuous medium is presented. The Nernst-Planck-Poisson model including Poisson equation for electric potential is used to describe transport of ions in the mitochondrial membrane—the interface which joins mitochondrial matrix with cellular cytosis. The transport of calcium ions is considered. Concentration of calcium inside the mitochondrion is not known accurately because different analytical methods give dramatically different results. We explain mathematically these differences assuming the complexing reaction inside mitochondrion and the existence of the calcium set-point (concentration of calcium in cytosis below which calcium stops entering the mitochondrion).

Space Suit Portable Life Support System (PLSS) 2.0 Pre-Installation Acceptance (PIA) Testing

NASA Technical Reports Server (NTRS)

Watts, Carly; Vogel, Matthew

2016-01-01

Following successful completion of the space suit Portable Life Support System (PLSS) 1.0 development and testing in 2011, the second system-level prototype, PLSS 2.0, was developed in 2012 to continue the maturation of the advanced PLSS design which is intended to reduce consumables, improve reliability and robustness, and incorporate additional sensing and functional capabilities over the current Space Shuttle/International Space Station Extravehicular Mobility Unit (EMU) PLSS. PLSS 2.0 represents the first attempt at a packaged design comprising first generation or later component prototypes and medium fidelity interfaces within a flight-like representative volume. Pre-Installation Acceptance (PIA) is carryover terminology from the Space Shuttle Program referring to the series of test sequences used to verify functionality of the EMU PLSS prior to installation into the Space Shuttle airlock for launch. As applied to the PLSS 2.0 development and testing effort, PIA testing designated the series of 27 independent test sequences devised to verify component and subsystem functionality, perform in situ instrument calibrations, generate mapping data to define set-points for control algorithms, evaluate hardware performance against advanced PLSS design requirements, and provide quantitative and qualitative feedback on evolving design requirements and performance specifications. PLSS 2.0 PIA testing was carried out from 3/20/13 - 3/15/14 using a variety of test configurations to perform test sequences that ranged from stand-alone component testing to system-level testing, with evaluations becoming increasingly integrated as the test series progressed. Each of the 27 test sequences was vetted independently, with verification of basic functionality required before completion. Because PLSS 2.0 design requirements were evolving concurrently with PLSS 2.0 PIA testing, the requirements were used as guidelines to assess performance during the tests; after the completion of PIA testing, test data served to improve the fidelity and maturity of design requirements as well as plans for future advanced PLSS functional testing.

Space Suit Portable Life Support System (PLSS) 2.0 Pre-Installation Acceptance (PIA) Testing

NASA Technical Reports Server (NTRS)

Anchondo, Ian; Cox, Marlon; Meginnis, Carly; Westheimer, David; Vogel, Matt R.

2016-01-01

Following successful completion of the space suit Portable Life Support System (PLSS) 1.0 development and testing in 2011, the second system-level prototype, PLSS 2.0, was developed in 2012 to continue the maturation of the advanced PLSS design. This advanced PLSS is intended to reduce consumables, improve reliability and robustness, and incorporate additional sensing and functional capabilities over the current Space Shuttle/International Space Station Extravehicular Mobility Unit (EMU) PLSS. PLSS 2.0 represents the first attempt at a packaged design comprising first generation or later component prototypes and medium fidelity interfaces within a flight-like representative volume. Pre-Installation Acceptance (PIA) is carryover terminology from the Space Shuttle Program referring to the series of test sequences used to verify functionality of the EMU PLSS prior to installation into the Space Shuttle airlock for launch. As applied to the PLSS 2.0 development and testing effort, PIA testing designated the series of 27 independent test sequences devised to verify component and subsystem functionality, perform in situ instrument calibrations, generate mapping data, define set-points, evaluate control algorithms, evaluate hardware performance against advanced PLSS design requirements, and provide quantitative and qualitative feedback on evolving design requirements and performance specifications. PLSS 2.0 PIA testing was carried out in 2013 and 2014 using a variety of test configurations to perform test sequences that ranged from stand-alone component testing to system-level testing, with evaluations becoming increasingly integrated as the test series progressed. Each of the 27 test sequences was vetted independently, with verification of basic functionality required before completion. Because PLSS 2.0 design requirements were evolving concurrently with PLSS 2.0 PIA testing, the requirements were used as guidelines to assess performance during the tests; after the completion of PIA testing, test data served to improve the fidelity and maturity of design requirements as well as plans for future advanced PLSS functional testing.

Atomic Force Microscopy of Isolated Nanostructures: Biomolecular Imaging in Hydrated Environments - Status and Future Prospects

NASA Astrophysics Data System (ADS)

Santos, Sergio; Thomson, Neil H.

The use of the atomic force microscope (AFM) in ambient conditions has some key advantages for characterising isolated nanostructures over other operating environments. The lack of a bulk liquid environment minimises motion of the sample to maximise resolution, while humidity control allows retention of surface water, keeping biomolecules sufficiently hydrated. The use of relatively stiff cantilevers in air (k > 10 N/m) prevents significant energy being transferred to higher modes or frequencies. This enables reliable modelling of the cantilever dynamics with relatively straightforward point mass and spring models. We show herein that combining modelling with experiment leads to robust interpretation of dynamic AFM in air. This understanding has led to new ways of operation, including a true non-contact mode in ambient and small amplitude small set-point (SASS) modes. These modes will be important to gain quantitative information about structure and processes on the nanoscale. We also discuss interpretation of height information obtained from AFM on the nanoscale and summarise a framework for recovery of apparent height loss for nanostructures. A combination of these methods will lead to a new era of quantitative AFM for nanoscience and nanotechnology.

Model-based optimal design of active cool thermal energy storage for maximal life-cycle cost saving from demand management in commercial buildings

DOE PAGES

Cui, Borui; Gao, Dian-ce; Xiao, Fu; ...

2016-12-23

This article provides a method in comprehensive evaluation of cost-saving potential of active cool thermal energy storage (CTES) integrated with HVAC system for demand management in non-residential building. The active storage is beneficial by shifting peak demand for peak load management (PLM) as well as providing longer duration and larger capacity of demand response (DR). In this research, a model-based optimal design method using genetic algorithm is developed to optimize the capacity of active CTES aiming for maximizing the life-cycle cost saving concerning capital cost associated with storage capacity as well as incentives from both fast DR and PLM. Inmore » the method, the active CTES operates under a fast DR control strategy during DR events while under the storage-priority operation mode to shift peak demand during normal days. The optimal storage capacities, maximum annual net cost saving and corresponding power reduction set-points during DR event are obtained by using the proposed optimal design method. Lastly, this research provides guidance in comprehensive evaluation of cost-saving potential of CTES integrated with HVAC system for building demand management including both fast DR and PLM.« less

Model-based optimal design of active cool thermal energy storage for maximal life-cycle cost saving from demand management in commercial buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Borui; Gao, Dian-ce; Xiao, Fu

This article provides a method in comprehensive evaluation of cost-saving potential of active cool thermal energy storage (CTES) integrated with HVAC system for demand management in non-residential building. The active storage is beneficial by shifting peak demand for peak load management (PLM) as well as providing longer duration and larger capacity of demand response (DR). In this research, a model-based optimal design method using genetic algorithm is developed to optimize the capacity of active CTES aiming for maximizing the life-cycle cost saving concerning capital cost associated with storage capacity as well as incentives from both fast DR and PLM. Inmore » the method, the active CTES operates under a fast DR control strategy during DR events while under the storage-priority operation mode to shift peak demand during normal days. The optimal storage capacities, maximum annual net cost saving and corresponding power reduction set-points during DR event are obtained by using the proposed optimal design method. Lastly, this research provides guidance in comprehensive evaluation of cost-saving potential of CTES integrated with HVAC system for building demand management including both fast DR and PLM.« less

Iron and fibroblast growth factor 23 in X-linked hypophosphatemia

PubMed Central

Imel, Erik A.; Gray, Amie; Padgett, Leah; Econs, Michael J.

2014-01-01

Background Excess fibroblast growth factor 23 (FGF23) causes hypophosphatemia in autosomal dominant hypophosphatemic rickets (ADHR) and X-linked hypophosphatemia (XLH). Iron status influences C-terminal FGF23 (incorporating fragments plus intact FGF23) in ADHR and healthy subjects, and intact FGF23 in ADHR. We hypothesized that in XLH serum iron would inversely correlate to C-terminal FGF23, but not to intact FGF23, mirroring the relationships in normal controls. Methods Subjects included 25 untreated outpatients with XLH at a tertiary medical center and 158 healthy adult controls. Serum iron and plasma intact FGF23 and C-terminal FGF23 were measured in stored samples. Results Intact FGF23 was greater than the control mean in 100% of XLH patients, and >2SD above the control mean in 88%, compared to 71% and 21% respectively for C-terminal FGF23. In XLH, iron correlated negatively to log-C-terminal FGF23 (r= −0.523, p<0.01), with a steeper slope than in controls (p<0.001). Iron was not related to log-intact FGF23 in either group. The log-ratio of intact FGF23 to C-terminal FGF23 was higher in XLH (0.00 ± 0.44) than controls (−0.28 ± 0.21, p<0.01), and correlated positively to serum iron (controls r= 0.276, p<0.001; XLH r= 0.428, p<0.05), with a steeper slope in XLH (p<0.01). Conclusion Like controls, serum iron in XLH is inversely related to C-terminal FGF23 but not intact FGF23. XLH patients are more likely to have elevated intact FGF23 than C-terminal FGF23. The relationships of iron to FGF23 in XLH suggest altered regulation of FGF23 cleaving may contribute to maintaining hypophosphatemia around an abnormal set-point. PMID:24325979

The laboratory environmental algae pond simulator (LEAPS) photobioreactor: Validation using outdoor pond cultures of Chlorella sorokiniana and Nannochloropsis salina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huesemann, M.; Williams, P.; Edmundson, S.

A bench-scale photobioreactor system, termed Laboratory Environmental Algae Pond Simulator (LEAPS), was designed and constructed to simulate outdoor pond cultivation for a wide range of geographical locations and seasons. The LEAPS consists of six well-mixed glass column photobioreactors sparged with CO2-enriched air to maintain a set-point pH, illuminated from above by a programmable multicolor LED lighting (0 to 2,500 µmol/m2-sec), and submerged in a temperature controlled water-bath (-2 °C to >60 °C). Measured incident light intensities and water temperatures deviated from the respective light and temperature set-points on average only 2.3% and 0.9%, demonstrating accurate simulation of light and temperaturemore » conditions measured in outdoor ponds. In order to determine whether microalgae strains cultured in the LEAPS exhibit the same linear phase biomass productivity as in outdoor ponds, Chlorella sorokiniana and Nannochloropsis salina were cultured in the LEAPS bioreactors using light and temperature scripts measured previously in the respective outdoor pond studies. For Chlorella sorokiniana, the summer season biomass productivity in the LEAPS was 6.6% and 11.3% lower than in the respective outdoor ponds in Rimrock, Arizona, and Delhi, California; however, these differences were not statistically significant. For Nannochloropsis salina, the winter season biomass productivity in the LEAPS was statistically significantly higher (15.2%) during the 27 day experimental period than in the respective outdoor ponds in Tucson, Arizona. However, when considering only the first 14 days, the LEAPS biomass productivity was only 9.2% higher than in the outdoor ponds, a difference shown to be not statistically significant. Potential reasons for the positive or negative divergence in LEAPS performance, relative to outdoor ponds, are discussed. To demonstrate the utility of the LEAPS in predicting productivity, two other strains – Scenedesmus obliquus and Stichococcus minor – were evaluated using the summer season script for Rimrock, Arizona. For both strains, the productivity was around 11.6 g/m2-day at a 25 cm culture depth. In conclusion, the LEAPS is an accurate pond simulator and thus offers a reliable, fast, and cost-effective way for screening microalgae strains and operating conditions for high biomass productivity and co-product yields, using sunlight intensity and water temperature scripts generated by the Biomass Assessment Tool for any geographic location of choice where meteorological data are available.« less

Heat regulation: homeostasis of central temperature in man.

PubMed

Benzinger, T H

1969-10-01

Focus is on the concept of the quantitative thermostat or setpoint as it evolved experimentally, not theoretically, from measurements of central temperature at the tympanic membrane and from measurements of physiological responses by human gradient layer calorimetry and continuous analysis of oxygen consumption. Heat-flow responses as they relate to stimuli by which they are evoked -- peripheral or central temperatures at thermoreceptive sites -- and discussed, and individual systems of reflex action are described. These systems are then correlated with what is known of their tangible components -- sensory receptors, effector organs, nervous centers, and afferent or efferent nervous pathways -- classically derived from anatomical studies, lesion experiments, recording of action currents, or electrical or thermal stimulation of pertinent structures. Such as correlation is a crucial test, and when the results are consistent, they provide independent, mutual confirmation via the 2 approaches. Doubts are then removed that lesions or interferences, which are unavoidable with most neurophysiological methods, may have produced artifacts. Conversely, calorimetry allows one to observe and analyze thermoregulation in process in a human subject without disturbing normal structures or functions other than by the stresses to which the body is made to respond. Prior to a description of experimental findings, the essential methods are reviewed. With the methods of gradient layer calorimetry, tympanic (eardrum) thermonetry, and indirect calorimetry, thermoregulatory responses -- by chemical overproduction of metabolic heat -- were observed in transient states as a result of a stimulus of cold impinging on peripheral neurons or warm-inhibition removed from central structures. With tympanic thermometry permitting for the 1st time om humans the continuous recording of central thermal stimulation, and with gradient calorimetry permitting the continuous recording (with insignificant inertial distortion) of the sweating responses in precisely controlled environments of a large variety and under conditions where complete evaporation of sweat is ensured by strong but smooth air convection, a new study of physical thermoregulation was initiated in 1958. The experimental results did not support the expection that sweating would follow the average temperature of the skin in the classical tradition, with skin warm-receptors as the hypothetical origin of exciting warm-impulses and cenral temperature as a participant prescribing the action of the "thermoregulator" in some as yet undetermined, additive, manner. Vasomotor mechanisms to human thermoregulation can be assessed in quantitative manner only by whole-body calorimetry. Mechanisms of thermal homeostasis also considered include hormonal regulation, transmitter substances, conscious sensation of warmth and coordinations of behavioral and autonomic mechanisms, setpoint and its variations, and fever.

Information spread in networks: Games, optimal control, and stabilization

NASA Astrophysics Data System (ADS)

Khanafer, Ali

This thesis focuses on designing efficient mechanisms for controlling information spread in networks. We consider two models for information spread. The first one is the well-known distributed averaging dynamics. The second model is a nonlinear one that describes virus spread in computer and biological networks. We seek to design optimal, robust, and stabilizing controllers under practical constraints. For distributed averaging networks, we study the interaction between a network designer and an adversary. We consider two types of attacks on the network. In Attack-I, the adversary strategically disconnects a set of links to prevent the nodes from reaching consensus. Meanwhile, the network designer assists the nodes in reaching consensus by changing the weights of a limited number of links in the network. We formulate two problems to describe this competition where the order in which the players act is reversed in the two problems. Although the canonical equations provided by the Pontryagin's Maximum Principle (MP) seem to be intractable, we provide an alternative characterization for the optimal strategies that makes connection to potential theory. Further, we provide a sufficient condition for the existence of a saddle-point equilibrium (SPE) for the underlying zero-sum game. In Attack-II, the designer and the adversary are both capable of altering the measurements of all nodes in the network by injecting global signals. We impose two constraints on both players: a power constraint and an energy constraint. We assume that the available energy to each player is not sufficient to operate at maximum power throughout the horizon of the game. We show the existence of an SPE and derive the optimal strategies in closed form for this attack scenario. As an alternative to the "network designer vs. adversary" framework, we investigate the possibility of stabilizing unknown network diffusion processes using a distributed mechanism, where the uncertainty is due to an attack on the network. To this end, we propose a distributed version of the classical logic-based supervisory control scheme. Given a network of agents whose dynamics contain unknown parameters, the distributed supervisory control scheme is used to assist the agents to converge to a certain set-point without requiring them to have explicit knowledge of that set-point. Unlike the classical supervisory control scheme where a centralized supervisor makes switching decisions among the candidate controllers, in our scheme, each agent is equipped with a local supervisor that switches among the available controllers. The switching decisions made at a certain agent depend only on the information from its neighboring agents. We provide sufficient conditions for stabilization and apply our framework to the distributed averaging problem in the presence of large modeling uncertainty. For infected networks, we study the stability properties of a susceptible-infected-susceptible (SIS) diffusion model, so-called the n-intertwined Markov model, over arbitrary network topologies. Similar to the majority of infection spread dynamics, this model exhibits a threshold phenomenon. When the curing rates in the network are high, the all-healthy state is the unique equilibrium over the network. Otherwise, an endemic equilibrium state emerges, where some infection remains within the network. Using notions from positive systems theory, we provide conditions for the global asymptotic stability of the equilibrium points in both cases over strongly and weakly connected directed networks based on the value of the basic reproduction number, a fundamental quantity in the study of epidemics. Furthermore, we demonstrate that the n-intertwined Markov model can be viewed as a best-response dynamical system of a concave game among the nodes. This characterization allows us to cast new infection spread dynamics; additionally, we provide a sufficient condition, for the global convergence to the all-healthy state, that can be checked in a distributed fashion. Moreover, we investigate the problem of stabilizing the network when the curing rates of a limited number of nodes can be controlled. In particular, we characterize the number of controllers required for a class of undirected graphs. We also design optimal controllers capable of minimizing the total infection in the network at minimum cost. Finally, we outline a set of open problems in the area of information spread control.

Servo-control for maintaining abdominal skin temperature at 36C in low birth weight infants.

PubMed

Sinclair, J C

2002-01-01

Randomized trials have shown that the neonatal mortality rate of low birth-weight babies can be reduced by keeping them warm. For low birth-weight babies nursed in incubators, warm conditions may be achieved either by heating the air to a desired temperature, or by servo-controlling the baby's body temperature at a desired set-point. In low birth weight infants, to determine the effect on death and other important clinical outcomes of targeting body temperature rather than air temperature as the end-point of control of incubator heating. Standard search strategy of the Cochrane Neonatal Review Group. Searches were made of the Cochrane Controlled Trials Register (CCTR) (Cochrane Library, Issue 4, 2001) and MEDLINE, 1966 to November 2001. Randomized or quasi-randomized trials which test the effects of having the heat output of the incubator servo-controlled from body temperature compared with setting a constant incubator air temperature. Trial methodologic quality was systematically assessed. Outcome measures included death, timing of death, cause of death, and other clinical outcomes. Categorical outcomes were analyzed using relative risk and risk difference. Meta-analysis assumed a fixed effect model. Two eligible trials were found. In total, they included 283 babies and 112 deaths. Compared to setting a constant incubator air temperature of 31.8C, servo-control of abdominal skin temperature at 36C reduces the neonatal death rate among low birth weight infants: relative risk 0.72 (95% CI 0.54, 0.97); risk difference -12.7% (95% CI -1.6, -23.9). This effect is even greater among VLBW infants. During at least the first week after birth, low birth weight babies should be provided with a carefully regulated thermal environment that is near the thermoneutral point. For LBW babies in incubators, this can be achieved by adjusting incubator temperature to maintain an anterior abdominal skin temperature of at least 36C, using either servo-control or frequent manual adjustment of incubator air temperature.

Anomaly Detection in Power Quality at Data Centers

NASA Technical Reports Server (NTRS)

Grichine, Art; Solano, Wanda M.

2015-01-01

The goal during my internship at the National Center for Critical Information Processing and Storage (NCCIPS) is to implement an anomaly detection method through the StruxureWare SCADA Power Monitoring system. The benefit of the anomaly detection mechanism is to provide the capability to detect and anticipate equipment degradation by monitoring power quality prior to equipment failure. First, a study is conducted that examines the existing techniques of power quality management. Based on these findings, and the capabilities of the existing SCADA resources, recommendations are presented for implementing effective anomaly detection. Since voltage, current, and total harmonic distortion demonstrate Gaussian distributions, effective set-points are computed using this model, while maintaining a low false positive count.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yijian; Hong, Mingyi; Dall'Anese, Emiliano

This paper considers power distribution systems featuring renewable energy sources (RESs), and develops a distributed optimization method to steer the RES output powers to solutions of AC optimal power flow (OPF) problems. The design of the proposed method leverages suitable linear approximations of the AC-power flow equations, and is based on the Alternating Direction Method of Multipliers (ADMM). Convergence of the RES-inverter output powers to solutions of the OPF problem is established under suitable conditions on the stepsize as well as mismatches between the commanded setpoints and actual RES output powers. In a broad sense, the methods and results proposedmore » here are also applicable to other distributed optimization problem setups with ADMM and inexact dual updates.« less

The quantitation of buffering action II. Applications of the formal & general approach.

PubMed

Schmitt, Bernhard M

2005-03-16

The paradigm of "buffering" originated in acid-base physiology, but was subsequently extended to other fields and is now used for a wide and diverse set of phenomena. In the preceding article, we have presented a formal and general approach to the quantitation of buffering action. Here, we use that buffering concept for a systematic treatment of selected classical and other buffering phenomena. H+ buffering by weak acids and "self-buffering" in pure water represent "conservative buffered systems" whose analysis reveals buffering properties that contrast in important aspects from classical textbook descriptions. The buffering of organ perfusion in the face of variable perfusion pressure (also termed "autoregulation") can be treated in terms of "non-conservative buffered systems", the general form of the concept. For the analysis of cytoplasmic Ca++ concentration transients (also termed "muffling"), we develop a related unit that is able to faithfully reflect the time-dependent quantitative aspect of buffering during the pre-steady state period. Steady-state buffering is shown to represent the limiting case of time-dependent muffling, namely for infinitely long time intervals and infinitely small perturbations. Finally, our buffering concept provides a stringent definition of "buffering" on the level of systems and control theory, resulting in four absolute ratio scales for control performance that are suited to measure disturbance rejection and setpoint tracking, and both their static and dynamic aspects. Our concept of buffering provides a powerful mathematical tool for the quantitation of buffering action in all its appearances.

On-Orbit and Ground Performance of the PGBA Plant Growth Facility

NASA Technical Reports Server (NTRS)

Hoehn, A.; Chamberlain, D. J.; Forsyth, S. W.; Hanna, D. S.; Scovazzo, P.; Stodieck, L. S.; Heyenga, G.; Kliss, Mark

1997-01-01

PGBA, a plant growth facility developed for commercial space biotechnology research, successfully grew a total of 30 plants (6 species) for 10 days on board the Space Shuttle Endeavour (STS-77) and is scheduled for reflight on board MSL-1 (STS-83) for a 16 day flight. The PGBA life support systems provide atmospheric, thermal, and humidity control as well as lighting and nutrient supply in a 23.6 liter chamber. Atmosphere treatment includes ethylene and other hydrocarbon removal, CO2 replenishment, and O2 control. The normally closed system uses controlled CO2 replenishment from the crew cabin as required by the plants. Temperature is controlled (1 C) at user-specified setpoints between 20-32 C, using water-filled coolant loops, solid state Peltier thermoelectric devices, and liquid heat exchangers. The thermoelectric cooling systems were optimized for low power consumption and high cooling efficiencies. Relative humidity is maintained between 60-100% using a cooled porous metal plate to remove water vapor from the air stream without cooling the bulk air below the dew point. The lighting system utilizes three compact fluorescent bi-axial lights with variable lighting control and light intensity (PAR) between 220 and 330 micromol/sq m/s at a distance of 20 cm in spaceflight configuration (on orbit power limited to 230 Watt for entire payload). A ground, up to 550 micromol/sq m/s light intensity can be achieved with 330 Watt payload power consumption. Plant water and nutrient support is sustained via the 'Nutrient Pack' system including the passive or active 'Water Replenishable Nutrient Pack.' The root matrix material (soil or Agar) and nutrient formulation of each pack is prepared according to plant species and experimental requirements. These systems were designed by NASA Ames personnel. Data acquisition and control systems provide 32 channels of environmental data as well as digitized or analog video signals for downlink.

Probing the lithium-response pathway in hiPSCs implicates the phosphoregulatory set-point for a cytoskeletal modulator in bipolar pathogenesis.

PubMed

Tobe, Brian T D; Crain, Andrew M; Winquist, Alicia M; Calabrese, Barbara; Makihara, Hiroko; Zhao, Wen-Ning; Lalonde, Jasmin; Nakamura, Haruko; Konopaske, Glenn; Sidor, Michelle; Pernia, Cameron D; Yamashita, Naoya; Wada, Moyuka; Inoue, Yuuka; Nakamura, Fumio; Sheridan, Steven D; Logan, Ryan W; Brandel, Michael; Wu, Dongmei; Hunsberger, Joshua; Dorsett, Laurel; Duerr, Cordulla; Basa, Ranor C B; McCarthy, Michael J; Udeshi, Namrata D; Mertins, Philipp; Carr, Steven A; Rouleau, Guy A; Mastrangelo, Lina; Li, Jianxue; Gutierrez, Gustavo J; Brill, Laurence M; Venizelos, Nikolaos; Chen, Guang; Nye, Jeffrey S; Manji, Husseini; Price, Jeffrey H; McClung, Colleen A; Akiskal, Hagop S; Alda, Martin; Chuang, De-Maw M; Coyle, Joseph T; Liu, Yang; Teng, Yang D; Ohshima, Toshio; Mikoshiba, Katsuhiko; Sidman, Richard L; Halpain, Shelley; Haggarty, Stephen J; Goshima, Yoshio; Snyder, Evan Y

2017-05-30

The molecular pathogenesis of bipolar disorder (BPD) is poorly understood. Using human-induced pluripotent stem cells (hiPSCs) to unravel such mechanisms in polygenic diseases is generally challenging. However, hiPSCs from BPD patients responsive to lithium offered unique opportunities to discern lithium's target and hence gain molecular insight into BPD. By profiling the proteomics of BDP-hiPSC-derived neurons, we found that lithium alters the phosphorylation state of collapsin response mediator protein-2 (CRMP2). Active nonphosphorylated CRMP2, which binds cytoskeleton, is present throughout the neuron; inactive phosphorylated CRMP2, which dissociates from cytoskeleton, exits dendritic spines. CRMP2 elimination yields aberrant dendritogenesis with diminished spine density and lost lithium responsiveness (LiR). The "set-point" for the ratio of pCRMP2:CRMP2 is elevated uniquely in hiPSC-derived neurons from LiR BPD patients, but not with other psychiatric (including lithium-nonresponsive BPD) and neurological disorders. Lithium (and other pathway modulators) lowers pCRMP2, increasing spine area and density. Human BPD brains show similarly elevated ratios and diminished spine densities; lithium therapy normalizes the ratios and spines. Consistent with such "spine-opathies," human LiR BPD neurons with abnormal ratios evince abnormally steep slopes for calcium flux; lithium normalizes both. Behaviorally, transgenic mice that reproduce lithium's postulated site-of-action in dephosphorylating CRMP2 emulate LiR in BPD. These data suggest that the "lithium response pathway" in BPD governs CRMP2's phosphorylation, which regulates cytoskeletal organization, particularly in spines, modulating neural networks. Aberrations in the posttranslational regulation of this developmentally critical molecule may underlie LiR BPD pathogenesis. Instructively, examining the proteomic profile in hiPSCs of a functional agent-even one whose mechanism-of-action is unknown-might reveal otherwise inscrutable intracellular pathogenic pathways.

DNA G-segment bending is not the sole determinant of topology simplification by type II DNA topoisomerases.

PubMed

Thomson, Neil H; Santos, Sergio; Mitchenall, Lesley A; Stuchinskaya, Tanya; Taylor, James A; Maxwell, Anthony

2014-08-21

DNA topoisomerases control the topology of DNA. Type II topoisomerases exhibit topology simplification, whereby products of their reactions are simplified beyond that expected based on thermodynamic equilibrium. The molecular basis for this process is unknown, although DNA bending has been implicated. To investigate the role of bending in topology simplification, the DNA bend angles of four enzymes of different types (IIA and IIB) were measured using atomic force microscopy (AFM). The enzymes tested were Escherichia coli topo IV and yeast topo II (type IIA enzymes that exhibit topology simplification), and Methanosarcina mazei topo VI and Sulfolobus shibatae topo VI (type IIB enzymes, which do not). Bend angles were measured using the manual tangent method from topographical AFM images taken with a novel amplitude-modulated imaging mode: small amplitude small set-point (SASS), which optimises resolution for a given AFM tip size and minimises tip convolution with the sample. This gave improved accuracy and reliability and revealed that all 4 topoisomerases bend DNA by a similar amount: ~120° between the DNA entering and exiting the enzyme complex. These data indicate that DNA bending alone is insufficient to explain topology simplification and that the 'exit gate' may be an important determinant of this process.

Metal site occupancy and allosteric switching in bacterial metal sensor proteins.

PubMed

Guerra, Alfredo J; Giedroc, David P

2012-03-15

All prokaryotes encode a panel of metal sensor or metalloregulatory proteins that govern the expression of genes that allows an organism to quickly adapt to toxicity or deprivation of both biologically essential transition metal ions, e.g., Zn, Cu, Fe, and heavy metal pollutants. As such, metal sensor proteins can be considered arbiters of intracellular transition metal bioavailability and thus potentially control the metallation state of the metalloproteins in the cell. Metal sensor proteins are specialized allosteric proteins that regulate transcription as a result direct binding of one or two cognate metal ions, to the exclusion of all others. In most cases, the binding of the cognate metal ion induces a structural change in a protein oligomer that either activates or inhibits operator DNA binding. A quantitative measure of the degree to which a particular metal drives metalloregulation of operator DNA-binding is the allosteric coupling free energy, ΔGc. In this review, we summarize recent work directed toward understanding metal occupancy and metal selectivity of these allosteric switches in selected families of metal sensor proteins and examine the structural origins of ΔGc in the functional context a thermodynamic "set-point" model of intracellular metal homeostasis. Copyright © 2011 Elsevier Inc. All rights reserved.

Model Development and Experimental Validation of the Fusible Heat Sink Design for Exploration Vehicles

NASA Technical Reports Server (NTRS)

Cognata, Thomas J.; Leimkuehler, Thomas O.; Sheth, Rubik B.; Le,Hung

2012-01-01

The Fusible Heat Sink is a novel vehicle heat rejection technology which combines a flow through radiator with a phase change material. The combined technologies create a multi-function device able to shield crew members against Solar Particle Events (SPE), reduce radiator extent by permitting sizing to the average vehicle heat load rather than to the peak vehicle heat load, and to substantially absorb heat load excursions from the average while constantly maintaining thermal control system setpoints. This multi-function technology provides great flexibility for mission planning, making it possible to operate a vehicle in hot or cold environments and under high or low heat load conditions for extended periods of time. This paper describes the model development and experimental validation of the Fusible Heat Sink technology. The model developed was intended to meet the radiation and heat rejection requirements of a nominal MMSEV mission. Development parameters and results, including sizing and model performance will be discussed. From this flight-sized model, a scaled test-article design was modeled, designed, and fabricated for experimental validation of the technology at Johnson Space Center thermal vacuum chamber facilities. Testing showed performance comparable to the model at nominal loads and the capability to maintain heat loads substantially greater than nominal for extended periods of time.

Model Development and Experimental Validation of the Fusible Heat Sink Design for Exploration Vehicles

NASA Technical Reports Server (NTRS)

Cognata, Thomas J.; Leimkuehler, Thomas; Sheth, Rubik; Le, Hung

2013-01-01

The Fusible Heat Sink is a novel vehicle heat rejection technology which combines a flow through radiator with a phase change material. The combined technologies create a multi-function device able to shield crew members against Solar Particle Events (SPE), reduce radiator extent by permitting sizing to the average vehicle heat load rather than to the peak vehicle heat load, and to substantially absorb heat load excursions from the average while constantly maintaining thermal control system setpoints. This multi-function technology provides great flexibility for mission planning, making it possible to operate a vehicle in hot or cold environments and under high or low heat load conditions for extended periods of time. This paper describes the modeling and experimental validation of the Fusible Heat Sink technology. The model developed was intended to meet the radiation and heat rejection requirements of a nominal MMSEV mission. Development parameters and results, including sizing and model performance will be discussed. From this flight-sized model, a scaled test-article design was modeled, designed, and fabricated for experimental validation of the technology at Johnson Space Center thermal vacuum chamber facilities. Testing showed performance comparable to the model at nominal loads and the capability to maintain heat loads substantially greater than nominal for extended periods of time.

DNA G-segment bending is not the sole determinant of topology simplification by type II DNA topoisomerases

NASA Astrophysics Data System (ADS)

Thomson, Neil H.; Santos, Sergio; Mitchenall, Lesley A.; Stuchinskaya, Tanya; Taylor, James A.; Maxwell, Anthony

2014-08-01

DNA topoisomerases control the topology of DNA. Type II topoisomerases exhibit topology simplification, whereby products of their reactions are simplified beyond that expected based on thermodynamic equilibrium. The molecular basis for this process is unknown, although DNA bending has been implicated. To investigate the role of bending in topology simplification, the DNA bend angles of four enzymes of different types (IIA and IIB) were measured using atomic force microscopy (AFM). The enzymes tested were Escherichia coli topo IV and yeast topo II (type IIA enzymes that exhibit topology simplification), and Methanosarcina mazei topo VI and Sulfolobus shibatae topo VI (type IIB enzymes, which do not). Bend angles were measured using the manual tangent method from topographical AFM images taken with a novel amplitude-modulated imaging mode: small amplitude small set-point (SASS), which optimises resolution for a given AFM tip size and minimises tip convolution with the sample. This gave improved accuracy and reliability and revealed that all 4 topoisomerases bend DNA by a similar amount: ~120° between the DNA entering and exiting the enzyme complex. These data indicate that DNA bending alone is insufficient to explain topology simplification and that the `exit gate' may be an important determinant of this process.

Lithium-associated primary hyperparathyroidism complicated by nephrogenic diabetes insipidus.

PubMed

Aksakal, Nihat; Erçetin, Candaş; Özçınar, Beyza; Aral, Ferihan; Erbil, Yeşim

2015-01-01

Lithium-associated hyperparathyroidism is the leading cause of hypercalcemia in lithium-treated patients. Lithium may lead to exacerbation of pre-existing primary hyperparathyroidism or cause an increased set-point of calcium for parathyroid hormone suppression, leading to parathyroid hyperplasia. Lithium may cause renal tubular concentration defects directly by the development of nephrogenic diabetes insipidus or indirectly by the effects of hypercalcemia. In this study, we present a female patient on long-term lithium treatment who was evaluated for hypercalcemia. Preoperative imaging studies indicated parathyroid adenoma and multinodular goiter. Parathyroidectomy and thyroidectomy were planned. During the postoperative course, prolonged intubation was necessary because of agitation and delirium. During this period, polyuria, severe dehydration, and hypernatremia developed, which responded to controlled hypotonic fluid infusions and was unresponsive to parenteral desmopressin. A diagnosis of nephrogenic diabetes insipidus was apparent. A parathyroid adenoma and multifocal papillary thyroid cancer were detected on histopathological examination. It was thought that nephrogenic diabetes insipidus was masked by hypercalcemia preoperatively. A patient on lithium treatment should be carefully followed up during or after surgery to prevent life-threatening complications of previously unrecognized nephrogenic diabetes insipidus, and the possibility of renal concentrating defects on long-term lithium use should be sought, particularly in patients with impaired consciousness.

Low-Pressure Long-Term Xenon Storage for Electric Propulsion

NASA Technical Reports Server (NTRS)

Back, Dwight D.; Ramos, Charlie; Meyer, John A.

2001-01-01

This Phase 2 effort demonstrated an alternative Xe storage and regulation system using activated carbon (AC) as a secondary storage media (ACSFR). This regulator system is nonmechanical, simple, inexpensive, and lighter. The ACSFR system isolates the thruster from the compressed gas tank, and allows independent multiple setpoint thruster operation. The flow using an ACSFR can also be throttled by applying increments in electrical power. Primary storage of Xe by AC is not superior to compressed gas storage with regard to weight, but AC storage can provide volume reduction, lower pressures in space, and potentially in situ Xe purification. With partial fill designs, a primary AC storage vessel for Xe could also eliminate problems with two-phase storage and regulate pressure. AC could also be utilized in long-term large quantity storage of Xe serving as a compact capture site for boil-off. Several Xe delivery ACSFR protocols between 2 and 45 sccm, and 15 min to 7 hr, were tested with an average flow variance of 1.2 percent, average power requirements of 5 W, and repeatability s of about 0.4 percent. Power requirements are affected by ACSFR bed sizing and flow rate/ duration design points, and these flow variances can be reduced by optimizing PID controller parameters.

A biomimetic vision-based hovercraft accounts for bees' complex behaviour in various corridors.

PubMed

Roubieu, Frédéric L; Serres, Julien R; Colonnier, Fabien; Franceschini, Nicolas; Viollet, Stéphane; Ruffier, Franck

2014-09-01

Here we present the first systematic comparison between the visual guidance behaviour of a biomimetic robot and those of honeybees flying in similar environments. We built a miniature hovercraft which can travel safely along corridors with various configurations. For the first time, we implemented on a real physical robot the 'lateral optic flow regulation autopilot', which we previously studied computer simulations. This autopilot inspired by the results of experiments on various species of hymenoptera consists of two intertwined feedback loops, the speed and lateral control loops, each of which has its own optic flow (OF) set-point. A heading-lock system makes the robot move straight ahead as fast as 69 cm s(-1) with a clearance from one wall as small as 31 cm, giving an unusually high translational OF value (125° s(-1)). Our biomimetic robot was found to navigate safely along straight, tapered and bent corridors, and to react appropriately to perturbations such as the lack of texture on one wall, the presence of a tapering or non-stationary section of the corridor and even a sloping terrain equivalent to a wind disturbance. The front end of the visual system consists of only two local motion sensors (LMS), one on each side. This minimalistic visual system measuring the lateral OF suffices to control both the robot's forward speed and its clearance from the walls without ever measuring any speeds or distances. We added two additional LMSs oriented at +/-45° to improve the robot's performances in stiffly tapered corridors. The simple control system accounts for worker bees' ability to navigate safely in six challenging environments: straight corridors, single walls, tapered corridors, straight corridors with part of one wall moving or missing, as well as in the presence of wind.

High efficiency digital cooler electronics for aerospace applications

NASA Astrophysics Data System (ADS)

Kirkconnell, C. S.; Luong, T. T.; Shaw, L. S.; Murphy, J. B.; Moody, E. A.; Lisiecki, A. L.; Ellis, M. J.

2014-06-01

Closed-cycle cryogenic refrigerators, or cryocoolers, are an enabling technology for a wide range of aerospace applications, mostly related to infrared (IR) sensors. While the industry focus has tended to be on the mechanical cryocooler thermo mechanical unit (TMU) alone, implementation on a platform necessarily consists of the combination of the TMU and a mating set of command and control electronics. For some applications the cryocooler electronics (CCE) are technologically simple and low cost relative to the TMU, but this is not always the case. The relative cost and complexity of the CCE for a space-borne application can easily exceed that of the TMU, primarily due to the technical constraints and cost impacts introduced by the typical space radiation hardness and reliability requirements. High end tactical IR sensor applications also challenge the state of the art in cryocooler electronics, such as those for which temperature setpoint and frequency must be adjustable, or those where an informative telemetry set must be supported, etc. Generally speaking for both space and tactical applications, it is often the CCE that limits the rated lifetime and reliability of the cryocooler system. A family of high end digital cryocooler electronics has been developed to address these needs. These electronics are readily scalable from 10W to 500W output capacity; experimental performance data for nominally 25W and 100W variants are presented. The combination of a FPGA-based controller and dual H-bridge motor drive architectures yields high efficiency (>92% typical) and precision temperature control (+/- 30 mK typical) for a wide range of Stirling-class mechanical cryocooler types and vendors. This paper focuses on recent testing with the AIM INFRAROT-MODULE GmbH (AIM) SX030 and AIM SF100 cryocoolers.

Application of phase matching autofocus in airborne long-range oblique photography camera

NASA Astrophysics Data System (ADS)

Petrushevsky, Vladimir; Guberman, Asaf

2014-06-01

The Condor2 long-range oblique photography (LOROP) camera is mounted in an aerodynamically shaped pod carried by a fast jet aircraft. Large aperture, dual-band (EO/MWIR) camera is equipped with TDI focal plane arrays and provides high-resolution imagery of extended areas at long stand-off ranges, at day and night. Front Ritchey-Chretien optics is made of highly stable materials. However, the camera temperature varies considerably in flight conditions. Moreover, a composite-material structure of the reflective objective undergoes gradual dehumidification in dry nitrogen atmosphere inside the pod, causing some small decrease of the structure length. The temperature and humidity effects change a distance between the mirrors by just a few microns. The distance change is small but nevertheless it alters the camera's infinity focus setpoint significantly, especially in the EO band. To realize the optics' resolution potential, the optimal focus shall be constantly maintained. In-flight best focus calibration and temperature-based open-loop focus control give mostly satisfactory performance. To get even better focusing precision, a closed-loop phase-matching autofocus method was developed for the camera. The method makes use of an existing beamsharer prism FPA arrangement where aperture partition exists inherently in an area of overlap between the adjacent detectors. The defocus is proportional to an image phase shift in the area of overlap. Low-pass filtering of raw defocus estimate reduces random errors related to variable scene content. Closed-loop control converges robustly to precise focus position. The algorithm uses the temperature- and range-based focus prediction as an initial guess for the closed-loop phase-matching control. The autofocus algorithm achieves excellent results and works robustly in various conditions of scene illumination and contrast.

Neural network feedforward control of a closed-circuit wind tunnel

NASA Astrophysics Data System (ADS)

Sutcliffe, Peter

Accurate control of wind-tunnel test conditions can be dramatically enhanced using feedforward control architectures which allow operating conditions to be maintained at a desired setpoint through the use of mathematical models as the primary source of prediction. However, as the desired accuracy of the feedforward prediction increases, the model complexity also increases, so that an ever increasing computational load is incurred. This drawback can be avoided by employing a neural network that is trained offline using the output of a high fidelity wind-tunnel mathematical model, so that the neural network can rapidly reproduce the predictions of the model with a greatly reduced computational overhead. A novel neural network database generation method, developed through the use of fractional factorial arrays, was employed such that a neural network can accurately predict wind-tunnel parameters across a wide range of operating conditions whilst trained upon a highly efficient database. The subsequent network was incorporated into a Neural Network Model Predictive Control (NNMPC) framework to allow an optimised output schedule capable of providing accurate control of the wind-tunnel operating parameters. Facilitation of an optimised path through the solution space is achieved through the use of a chaos optimisation algorithm such that a more globally optimum solution is likely to be found with less computational expense than the gradient descent method. The parameters associated with the NNMPC such as the control horizon are determined through the use of a Taguchi methodology enabling the minimum number of experiments to be carried out to determine the optimal combination. The resultant NNMPC scheme was employed upon the Hessert Low Speed Wind Tunnel at the University of Notre Dame to control the test-section temperature such that it follows a pre-determined reference trajectory during changes in the test-section velocity. Experimental testing revealed that the derived NNMPC controller provided an excellent level of control over the test-section temperature in adherence to a reference trajectory even when faced with unforeseen disturbances such as rapid changes in the operating environment.

Heel and toe driving on fuel cell vehicle

DOEpatents

Choi, Tayoung; Chen, Dongmei

2012-12-11

A system and method for providing nearly instantaneous power in a fuel cell vehicle. The method includes monitoring the brake pedal angle and the accelerator pedal angle of the vehicle, and if the vehicle driver is pressing both the brake pedal and the accelerator pedal at the same time and the vehicle is in a drive gear, activating a heel and toe mode. When the heel and toe mode is activated, the speed of a cathode compressor is increased to a predetermined speed set-point, which is higher than the normal compressor speed for the pedal position. Thus, when the vehicle brake is removed, the compressor speed is high enough to provide enough air to the cathode, so that the stack can generate nearly immediate power.

Regulation of Renewable Energy Sources to Optimal Power Flow Solutions Using ADMM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall-Anese, Emiliano; Zhang, Yijian; Hong, Mingyi

This paper considers power distribution systems featuring renewable energy sources (RESs), and develops a distributed optimization method to steer the RES output powers to solutions of AC optimal power flow (OPF) problems. The design of the proposed method leverages suitable linear approximations of the AC-power flow equations, and is based on the Alternating Direction Method of Multipliers (ADMM). Convergence of the RES-inverter output powers to solutions of the OPF problem is established under suitable conditions on the stepsize as well as mismatches between the commanded setpoints and actual RES output powers. In a broad sense, the methods and results proposedmore » here are also applicable to other distributed optimization problem setups with ADMM and inexact dual updates.« less

Obesity Impairs the Action of the Neuroendocrine Ghrelin System

PubMed Central

Zigman, Jeffrey M.; Bouret, Sebastien G.; Andrews, Zane B.

2016-01-01

Ghrelin is a metabolic hormone that promotes energy conservation by regulating appetite and energy expenditure. Although some studies suggest that antagonizing ghrelin function attenuates body weight gain and glucose intolerance on a high calorie diet, there is little information about the metabolic actions of ghrelin in the obese state. In this review, we discuss the novel concept of obesity-induced central ghrelin resistance in neural circuits regulating behavior, and impaired ghrelin secretion from the stomach. Interestingly, weight loss restores ghrelin secretion and function, and we hypothesize that ghrelin resistance is a mechanism designed to protect a higher body weight set-point established during times of food availability, to maximize energy reserves during a time of food scarcity. PMID:26542050

HIV and host immunogenetics: unraveling the role of HLA-C.

PubMed

Bardeskar, N S; Mania-Pramanik, J

2016-11-01

Host genetic factors play a major role in determining the outcome of many infections including human immunodeficiency virus (HIV). Multiple host factors have been studied till date showing their varied role in susceptibility or resistance to HIV infection. HLA-C, however, has been recently started gaining interest in researchers mind revealing its polymorphisms to have an important effect on viral load set-points, disease progression as well as transmission. In this review report, we have compiled these significant findings of HLA-C in HIV infection, in an attempt to highlight the need for further research in the area in different ethnic population to establish its role in the infection. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Optimization of a mainstream nitritation-denitritation process and anammox polishing.

PubMed

Regmi, Pusker; Holgate, Becky; Fredericks, Dana; Miller, Mark W; Wett, Bernhard; Murthy, Sudhir; Bott, Charles B

2015-01-01

This paper deals with an almost 1-year long pilot study of a nitritation-denitritation process that was followed by anammox polishing. The pilot plant treated real municipal wastewater at ambient temperatures. The effluent of high-rate activated sludge process (hydraulic retention time, HRT=30 min, solids retention time=0.25 d) was fed to the pilot plant described in this paper, where a constant temperature of 23 °C was maintained. The nitritation-denitritation process was operated to promote nitrite oxidizing bacteria out-selection in an intermittently aerated reactor. The intermittent aeration pattern was controlled using a strategy based on effluent ammonia and nitrate+nitrite concentrations. The unique feature of this aeration control was that fixed dissolved oxygen set-point was used and the length of aerobic and anoxic durations were changed based on the effluent ammonia and nitrate+nitrite concentrations. The anaerobic ammonia oxidation (anammox) bacteria were adapted in mainstream conditions by allowing the growth on the moving bed bioreactor plastic media in a fully anoxic reactor. The total inorganic nitrogen (TIN) removal performance of the entire system was 75±15% during the study at a modest influent chemical oxygen demand (COD)/NH4+-N ratio of 8.9±1.8 within the HRT range of 3.1-9.4 h. Anammox polishing contributed 11% of overall TIN removal. Therefore, this pilot-scale study demonstrates that application of the proposed nitritation-denitritation system followed by anammox polishing is capable of relatively high nitrogen removal without supplemental carbon and alkalinity at a low HRT.

Decreased precision contributes to the hypoxic thermoregulatory response in lizards.

PubMed

Cadena, Viviana; Tattersall, Glenn J

2009-01-01

The decrease in body temperature (T(b)) observed in most vertebrate classes in response to hypoxia has been attributed to a regulated decrease in set-point, protecting organs against tissue death due to oxygen depletion. Hypoxia, however, imparts particular challenges to metabolic function which may, in turn, affect thermoregulation. In ectotherms, where thermoregulation is mainly behavioural, stressors that influence the propensity to move and respond to temperature gradients are expected to have an impact on thermoregulatory control. Using low oxygen as a potent stressor, we evaluated the variability and level of thermoregulation of inland bearded dragons. To examine the source of thermoregulatory variability, we studied their behaviour in an electronically controlled temperature-choice shuttle box, a constant temperature dual-choice shuttle box, and a linear thermal gradient. A significant increase in the size of the T(b) range was observed at the lowest oxygen concentration (4% O(2)), reflecting a decrease in thermoregulatory precision in the temperature-choice shuttle box. This was also accompanied by a drop of approximately 2-4 degrees C in T(b), the drop being greatest in situations where T(b) must be actively defended. Situations that force the lizards to continually choose temperatures, rather than passively remain at a given temperature, lead to an increase in the variability in the manifested T(b), which is further exaggerated in hypoxia. This study reveals that a decrease in thermoregulatory precision caused by a diminished propensity to move or effect appropriate thermoregulatory responses may be a contributing component in the lowering of selected body temperatures observed in many hypoxic ectotherms.

It was a first class start which laid the basis for a promising future: Experience from comparative studies on gravity related behavior in animals and consequences for future experiments

NASA Astrophysics Data System (ADS)

Horn, Eberhard R.

2000-01-01

The main title was chosen in imitation of the headline of a lecture given by H. S. Wolff at the ESA-Symposium ``Life Odyssey'' in Maastricht/NL (1999) to contrast his pessimistic view of the science output from biological microgravity studies during the past 25 years with an optimistic view of the author who had the opportunity for studies on the gravity sensory systems of developing vertebrates and insects during the space missions STS-55, STS-84, and STS-90, and who was stimulated by this experience to undertake any effort to extend these studies on the International Space Station ISS. We studied compensatory eye and head movements induced by a lateral roll of the animals, and we found that exposure to both microgravity and hypergravity affect their development. Future studies have to consider long-term exposures to altered gravitational conditions to find answers to two questions, the mechanisms of adaptation during exposure, and the degree of residual effects after becoming an adult animal and also after re-entry to IG-conditions. The main hypothesis on the development of animals in space is that a fertilized egg will be converted to a normal adult animal guided by physiological and morphological set-points which represent the genetic program. In case of developmental retardations or accelerations or otherwise occurring deviations from normal structural and physiological development during specific periods of the embryonic and postembryonic life, these genetically defined supervisors activate readaptive mechanisms which direct the developmental processes towards normality, i.e., stability. Thus, an orbit-stabilized organism will be dramatically disturbed after return to Earth. Because this failure will need support to reach neuronal stability, research has also to consider the analysis of mechanisms which are able to overcome these disturbances. This research will open the door to applications because it forms a bridge to human medicine with its analytical research on control procedures over neuropathological mechanisms. .

Improving electrical power systems reliability through locally controlled distributed curtailable load

NASA Astrophysics Data System (ADS)

Dehbozorgi, Mohammad Reza

2000-10-01

Improvements in power system reliability have always been of interest to both power companies and customers. Since there are no sizable electrical energy storage elements in electrical power systems, the generated power should match the load demand at any given time. Failure to meet this balance may cause severe system problems, including loss of generation and system blackouts. This thesis proposes a methodology which can respond to either loss of generation or loss of load. It is based on switching of electric water heaters using power system frequency as the controlling signal. The proposed methodology encounters, and the thesis has addressed, the following associated problems. The controller must be interfaced with the existing thermostat control. When necessary to switch on loads, the water in the tank should not be overheated. Rapid switching of blocks of load, or chattering, has been considered. The contributions of the thesis are: (A) A system has been proposed which makes a significant portion of the distributed loads connected to a power system to behave in a predetermined manner to improve the power system response during disturbances. (B) The action of the proposed system is transparent to the customers. (C) The thesis proposes a simple analysis for determining the amount of such loads which might be switched and relates this amount to the size of the disturbances which can occur in the utility. (D) The proposed system acts without any formal communication links, solely using the embedded information present system-wide. (E) The methodology of the thesis proposes switching of water heater loads based on a simple, localized frequency set-point controller. The thesis has identified the consequent problem of rapid switching of distributed loads, which is referred to as chattering. (F) Two approaches have been proposed to reduce chattering to tolerable levels. (G) A frequency controller has been designed and built according to the specifications required to switch electric water heater loads in response to power system disturbances. (H) A cost analysis for building and installing the distributed frequency controller has been carried out. (I) The proposed equipment and methodology has been implemented and tested successfully. (Abstract shortened by UMI.)

Effects of wireless packet loss in industrial process control systems.

PubMed

Liu, Yongkang; Candell, Richard; Moayeri, Nader

2017-05-01

Timely and reliable sensing and actuation control are essential in networked control. This depends on not only the precision/quality of the sensors and actuators used but also on how well the communications links between the field instruments and the controller have been designed. Wireless networking offers simple deployment, reconfigurability, scalability, and reduced operational expenditure, and is easier to upgrade than wired solutions. However, the adoption of wireless networking has been slow in industrial process control due to the stochastic and less than 100% reliable nature of wireless communications and lack of a model to evaluate the effects of such communications imperfections on the overall control performance. In this paper, we study how control performance is affected by wireless link quality, which in turn is adversely affected by severe propagation loss in harsh industrial environments, co-channel interference, and unintended interference from other devices. We select the Tennessee Eastman Challenge Model (TE) for our study. A decentralized process control system, first proposed by N. Ricker, is adopted that employs 41 sensors and 12 actuators to manage the production process in the TE plant. We consider the scenario where wireless links are used to periodically transmit essential sensor measurement data, such as pressure, temperature and chemical composition to the controller as well as control commands to manipulate the actuators according to predetermined setpoints. We consider two models for packet loss in the wireless links, namely, an independent and identically distributed (IID) packet loss model and the two-state Gilbert-Elliot (GE) channel model. While the former is a random loss model, the latter can model bursty losses. With each channel model, the performance of the simulated decentralized controller using wireless links is compared with the one using wired links providing instant and 100% reliable communications. The sensitivity of the controller to the burstiness of packet loss is also characterized in different process stages. The performance results indicate that wireless links with redundant bandwidth reservation can meet the requirements of the TE process model under normal operational conditions. When disturbances are introduced in the TE plant model, wireless packet loss during transitions between process stages need further protection in severely impaired links. Techniques such as retransmission scheduling, multipath routing and enhanced physical layer design are discussed and the latest industrial wireless protocols are compared. Published by Elsevier Ltd.

Effects of Wireless Packet Loss in Industrial Process Control Systems

PubMed Central

Liu, Yongkang; Candell, Richard; Moayeri, Nader

2017-01-01

Timely and reliable sensing and actuation control are essential in networked control. This depends on not only the precision/quality of the sensors and actuators used but also on how well the communications links between the field instruments and the controller have been designed. Wireless networking offers simple deployment, reconfigurability, scalability, and reduced operational expenditure, and is easier to upgrade than wired solutions. However, the adoption of wireless networking has been slow in industrial process control due to the stochastic and less than 100 % reliable nature of wireless communications and lack of a model to evaluate the effects of such communications imperfections on the overall control performance. In this paper, we study how control performance is affected by wireless link quality, which in turn is adversely affected by severe propagation loss in harsh industrial environments, co-channel interference, and unintended interference from other devices. We select the Tennessee Eastman Challenge Model (TE) for our study. A decentralized process control system, first proposed by N. Ricker, is adopted that employs 41 sensors and 12 actuators to manage the production process in the TE plant. We consider the scenario where wireless links are used to periodically transmit essential sensor measurement data, such as pressure, temperature and chemical composition to the controller as well as control commands to manipulate the actuators according to predetermined setpoints. We consider two models for packet loss in the wireless links, namely, an independent and identically distributed (IID) packet loss model and the two-state Gilbert-Elliot (GE) channel model. While the former is a random loss model, the latter can model bursty losses. With each channel model, the performance of the simulated decentralized controller using wireless links is compared with the one using wired links providing instant and 100 % reliable communications. The sensitivity of the controller to the burstiness of packet loss is also characterized in different process stages. The performance results indicate that wireless links with redundant bandwidth reservation can meet the requirements of the TE process model under normal operational conditions. When disturbances are introduced in the TE plant model, wireless packet loss during transitions between process stages need further protection in severely impaired links. Techniques such as retransmission scheduling, multipath routing and enhanced physical layer design are discussed and the latest industrial wireless protocols are compared. PMID:28190566

Energy Performance and Optimal Control of Air-conditioned Buildings Integrated with Phase Change Materials

NASA Astrophysics Data System (ADS)

Zhu, Na

This thesis presents an overview of the previous research work on dynamic characteristics and energy performance of buildings due to the integration of PCMs. The research work on dynamic characteristics and energy performance of buildings using PCMs both with and without air-conditioning is reviewed. Since the particular interest in using PCMs for free cooling and peak load shifting, specific research efforts on both subjects are reviewed separately. A simplified physical dynamic model of building structures integrated with SSPCM (shaped-stabilized phase change material) is developed and validated in this study. The simplified physical model represents the wall by 3 resistances and 2 capacitances and the PCM layer by 4 resistances and 2 capacitances respectively while the key issue is the parameter identification of the model. This thesis also presents the studies on the thermodynamic characteristics of buildings enhanced by PCM and on the investigation of the impacts of PCM on the building cooling load and peak cooling demand at different climates and seasons as well as the optimal operation and control strategies to reduce the energy consumption and energy cost by reducing the air-conditioning energy consumption and peak load. An office building floor with typical variable air volume (VAV) air-conditioning system is used and simulated as the reference building in the comparison study. The envelopes of the studied building are further enhanced by integrating the PCM layers. The building system is tested in two selected cities of typical climates in China including Hong Kong and Beijing. The cold charge and discharge processes, the operation and control strategies of night ventilation and the air temperature set-point reset strategy for minimizing the energy consumption and electricity cost are studied. This thesis presents the simulation test platform, the test results on the cold storage and discharge processes, the air-conditioning energy consumption and demand reduction potentials in typical air-conditioning seasons in typical China cites as well as the impacts of operation and control strategies.

Modelling and regulating of cardio-respiratory response for the enhancement of interval training

PubMed Central

2014-01-01

Background The interval training method has been a well known exercise protocol which helps strengthen and improve one’s cardiovascular fitness. Purpose To develop an effective training protocol to improve cardiovascular fitness based on modelling and analysis of Heart Rate (HR) and Oxygen Uptake (VO2) dynamics. Methods In order to model the cardiorespiratory response to the onset and offset exercises, the (K4b2, Cosmed) gas analyzer was used to monitor and record the heart rate and oxygen uptake for ten healthy male subjects. An interval training protocol was developed for young health users and was simulated using a proposed RC switching model which was presented to accommodate the variations of the cardiorespiratory dynamics to running exercises. A hybrid system model was presented to describe the adaptation process and a multi-loop PI control scheme was designed for the tuning of interval training regime. Results By observing the original data for each subject, we can clearly identify that all subjects have similar HR and VO2 profiles. The proposed model is capable to simulate the exercise responses during onset and offset exercises; it ensures the continuity of the outputs within the interval training protocol. Under some mild assumptions, a hybrid system model can describe the adaption process and accordingly a multi-loop PI controller can be designed for the tuning of interval training protocol. The self-adaption feature of the proposed controller gives the exerciser the opportunity to reach his desired setpoints after a certain number of training sessions. Conclusions The established interval training protocol targets a range of 70-80% of HRmax which is mainly a training zone for the purpose of cardiovascular system development and improvement. Furthermore, the proposed multi-loop feedback controller has the potential to tune the interval training protocol according to the feedback from an individual exerciser. PMID:24499131

The application of the electrodynamic separator in minerals beneficiation

NASA Astrophysics Data System (ADS)

Skowron, M.; Syrek, P.; Surowiak, A.

2017-05-01

The aim of presented paper is elaboration of methodology of upgrading natural minerals in example of chalcocite and bornite sample. The results were obtained by means of laboratory drum separator. This device operates in accordance to properties of materials, which in this case was electrical conductivity. The study contains the analysis of the forces occurring inside of electrodynamic separator chamber, that act on the particles of various electrical properties. Both, the potential and electric field strength distributions were calculated, with set of separators setpoints. Theoretical analysis influenced on separator parameters, and hence impacted the empirical results too. Next, the authors conducted empirical research on chalcocite and bornite beneficiation by means of electrodynamic separation. The results of this process were shown graphically in form of upgrading curves of chalcocite considering elementary copper and lead.

Minimizing N2O emissions and carbon footprint on a full-scale activated sludge sequencing batch reactor.

PubMed

Rodriguez-Caballero, A; Aymerich, I; Marques, Ricardo; Poch, M; Pijuan, M

2015-03-15

A continuous, on-line quantification of the nitrous oxide (N2O) emissions from a full-scale sequencing batch reactor (SBR) placed in a municipal wastewater treatment plant (WWTP) was performed in this study. In general, N2O emissions from the biological wastewater treatment system were 97.1 ± 6.9 g N2O-N/Kg [Formula: see text] consumed or 6.8% of the influent [Formula: see text] load. In the WWTP of this study, N2O emissions accounted for over 60% of the total carbon footprint of the facility, on average. Different cycle configurations were implemented in the SBR aiming at reaching acceptable effluent values. Each cycle configuration consisted of sequences of aerated and non-aerated phases of different time length being controlled by the ammonium set-point fixed. Cycles with long aerated phases showed the largest N2O emissions, with the consequent increase in carbon footprint. Cycle configurations with intermittent aeration (aerated phases up to 20-30 min followed by short anoxic phases) were proven to effectively reduce N2O emissions, without compromising nitrification performance or increasing electricity consumption. This is the first study in which a successful operational strategy for N2O mitigation is identified at full-scale. Copyright © 2014 Elsevier Ltd. All rights reserved.

Technical Basis for Evaluating Software-Related Common-Cause Failures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muhlheim, Michael David; Wood, Richard

2016-04-01

The instrumentation and control (I&C) system architecture at a nuclear power plant (NPP) incorporates protections against common-cause failures (CCFs) through the use of diversity and defense-in-depth. Even for well-established analog-based I&C system designs, the potential for CCFs of multiple systems (or redundancies within a system) constitutes a credible threat to defeating the defense-in-depth provisions within the I&C system architectures. The integration of digital technologies into the I&C systems provides many advantages compared to the aging analog systems with respect to reliability, maintenance, operability, and cost effectiveness. However, maintaining the diversity and defense-in-depth for both the hardware and software within themore » digital system is challenging. In fact, the introduction of digital technologies may actually increase the potential for CCF vulnerabilities because of the introduction of undetected systematic faults. These systematic faults are defined as a “design fault located in a software component” and at a high level, are predominately the result of (1) errors in the requirement specification, (2) inadequate provisions to account for design limits (e.g., environmental stress), or (3) technical faults incorporated in the internal system (or architectural) design or implementation. Other technology-neutral CCF concerns include hardware design errors, equipment qualification deficiencies, installation or maintenance errors, instrument loop scaling and setpoint mistakes.« less

Influence of Applied Thermal Gradients and a Static Magnetic Field on Bridgman-Grown GeSi Alloys

NASA Technical Reports Server (NTRS)

Volz, M. P.; Szofran, F. R.; Cobb, S. D.; Ritter, T. M.

1999-01-01

The effect of applied axial and radial thermal gradients and an axial static magnetic field on the macrosegregation profiles of Bridgman-grown GeSi alloy crystals has been assessed. The axial thermal gradients were adjusted by changing the control setpoints of a seven-zone vertical Bridgman furnace. The radial thermal gradients were affected by growing samples in ampoules with different thermal conductivities, namely graphite, hot-pressed boron nitride (BN), and pyrolytic boron nitride (PBN). Those samples grown in a graphite ampoule exhibited radial profiles consistent with a highly concave interface and axial profiles indicative of complete mixing in the melt. The samples grown in BN and PBN ampoules had less radial variation. Axial macrosegregation profiles of these samples fell between the predictions for a completely mixed melt and one where solute transport is dominated by diffusion. All of the samples were grown on Ge seeds. This resulted in a period of free growth until the Si concentration in the solid was in equilibrium with the Si concentration in the liquid. The length of crystal grown during this period was inversely proportional to the applied axial thermal gradient. Several samples were grown in an axial 5 Tesla magnetic field. Measured macroscopic segregation profiles on these samples indicate that the magnetic field did not, in general, reduce the melt flow velocities to below the growth velocities.

Selection and Application of Sulfide Oxidizing Microorganisms Able to Withstand Thiols in Gas Biodesulfurization Systems.

PubMed

Roman, Pawel; Klok, Johannes B M; Sousa, João A B; Broman, Elias; Dopson, Mark; Van Zessen, Erik; Bijmans, Martijn F M; Sorokin, Dimitry Y; Janssen, Albert J H

2016-12-06

After the first commercial applications of a new biological process for the removal of hydrogen sulfide (H 2 S) from low pressure biogas, the need arose to broaden the operating window to also enable the removal of organosulfur compounds from high pressure sour gases. In this study we have selected microorganisms from a full-scale biodesulfurization system that are capable of withstanding the presence of thiols. This full-scale unit has been in stable operation for more than 10 years. We investigated the microbial community by using high-throughput sequencing of 16S rRNA gene amplicons which showed that methanethiol gave a competitive advantage to bacteria belonging to the genera Thioalkalibacter (Halothiobacillaceae family) and Alkalilimnicola (Ectothiorhosdospiraceae family). The sulfide-oxidizing potential of the acclimatized population was investigated under elevated thiol loading rates (4.5-9.1 mM d -1 ), consisting of a mix of methanethiol, ethanethiol, and propanethiol. With this biomass, it was possible to achieve a stable bioreactor operation at which 80% of the supplied H 2 S (61 mM d -1 ) was biologically oxidized to elemental sulfur. The remainder was chemically produced thiosulfate. Moreover, we found that a conventionally applied method for controlling the oxygen supply to the bioreactor, that is, by maintaining a redox potential set-point value, appeared to be ineffective in the presence of thiols.

Calibration improvements to electronically scanned pressure systems and preliminary statistical assessment

NASA Technical Reports Server (NTRS)

Everhart, Joel L.

1996-01-01

Orifice-to-orifice inconsistencies in data acquired with an electronically-scanned pressure system at the beginning of a wind tunnel experiment forced modifications to the standard, instrument calibration procedures. These modifications included a large increase in the number of calibration points which would allow a critical examination of the calibration curve-fit process, and a subsequent post-test reduction of the pressure data. Evaluation of these data has resulted in an improved functional representation of the pressure-voltage signature for electronically-scanned pressures sensors, which can reduce the errors due to calibration curve fit to under 0.10 percent of reading compared to the manufacturer specified 0.10 percent of full scale. Application of the improved calibration function allows a more rational selection of the calibration set-point pressures. These pressures should be adjusted to achieve a voltage output which matches the physical shape of the pressure-voltage signature of the sensor. This process is conducted in lieu of the more traditional approach where a calibration pressure is specified and the resulting sensor voltage is recorded. The fifteen calibrations acquired over the two-week duration of the wind tunnel test were further used to perform a preliminary, statistical assessment of the variation in the calibration process. The results allowed the estimation of the bias uncertainty for a single instrument calibration; and, they form the precursor for more extensive and more controlled studies in the laboratory.

Thermal comfort in naturally ventilated and air-conditioned buildings in humid subtropical climate zone in China

NASA Astrophysics Data System (ADS)

Yang, Wei; Zhang, Guoqiang

2008-05-01

A thermal comfort field study has been carried out in five cities in the humid subtropical climate zone in China. The survey was performed in naturally ventilated and air-conditioned buildings during the summer season in 2006. There were 229 occupants from 111 buildings who participated in this study and 229 questionnaire responses were collected. Thermal acceptability assessment reveals that the indoor environment in naturally ventilated buildings could not meet the 80% acceptability criteria prescribed by ASHRAE Standard 55, and people tended to feel more comfortable in air-conditioned buildings with the air-conditioned occupants voting with higher acceptability (89%) than the naturally ventilated occupants (58%). The neutral temperatures in naturally ventilated and air-conditioned buildings were 28.3°C and 27.7°C, respectively. The range of accepted temperature in naturally ventilated buildings (25.0˜31.6°C) was wider than that in air-conditioned buildings (25.1˜30.3°C), which suggests that occupants in naturally ventilated buildings seemed to be more tolerant of higher temperatures. Preferred temperatures were 27.9°C and 27.3°C in naturally ventilated and air-conditioned buildings, respectively, both of which were 0.4°C cooler than neutral temperatures. This result suggests that people of hot climates may use words like “slightly cool” to describe their preferred thermal state. The relationship between draught sensation and indoor air velocity at different temperature ranges indicates that indoor air velocity had a significant influence over the occupants’ comfort sensation, and air velocities required by occupants increased with the increasing of operative temperatures. Thus, an effective way of natural ventilation which can create the preferred higher air movement is called for. Finally, the indoor set-point temperature of 26°C or even higher in air-conditioned buildings was confirmed as making people comfortable, which supports the regulation in China that in public and office buildings the set-point temperature of air-conditioning system should not be lower than 26°C.

The selfish brain: competition for energy resources.

PubMed

Fehm, H L; Kern, W; Peters, A

2006-01-01

Although the brain constitutes only 2% of the body mass, its metabolism accounts for 50% of total body glucose utilization. This delicate situation is aggravated by the fact that the brain depends on glucose as energy substrate. Thus, the contour of a major problem becomes evident: how can the brain maintain constant fluxes of large amounts of glucose to itself in the presence of powerful competitors as fat and muscle tissue. Activity of cortical neurons generates an "energy on demand" signal which eventually mediates the uptake of glucose from brain capillaries. Because energy stores in the circulation (equivalent to ca. 5 g glucose) are also limited, a second signal is required termed "energy on request"; this signal is responsible for the activation of allocation processes. The term "allocation" refers to the activation of the "behavior control column" by an input from the hippocampus-amygdala system. As far as eating behavior is concerned the behavior control column consists of the ventral medial hypothalamus (VMH) and periventricular nucleus (PVN). The PVN represents the central nucleus of the brain's stress systems, the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS). Activation of the sympatico-adrenal system inhibits glucose uptake by peripheral tissues by inhibiting insulin release and inducing insulin resistance and increases hepatic glucose production. With an inadequate "energy on request" signal neuroglucopenia would be the consequence. A decrease in brain glucose can activate glucose-sensitive neurons in the lateral hypothalamus (LH) with the release of orexigenic peptides which stimulate food intake. If the energy supply of the brain depends on activation of the LH rather than on increased allocation to the brain, an increase in body weight is evitable. An increase in fat mass will generate feedback signals as leptin and insulin, which activate the arcuate nucleus. Activation of arcuate nucleus in turn will stimulate the activity of the PVN in a way similar to the activation by the hippocampus-amydala system. The activity of PVN is influenced by the hippocampal outflow which in turn is the consequence of a balance of low-affinity and high-affinity glucocorticoid receptors. This set-point can permanently be displaced by extreme stress situations, by starvation, exercise, hormones, drugs or by endocrine-disrupting chemicals. Disorders in the "energy on request" process will influence the allocation of energy and in so doing alter the body mass of the organism. In this "selfish brain theory" the neocortex and the limbic system play a central role in the pathogenesis of diseases, such as anorexia nervosa, obesity and diabetes mellitus type II. From these considerations it appears that the primary disturbance in obesity is a displacement of the hippocampal set-point of the system. The resulting permanent activation of the feedback system must result in a likewise permanent activation of the sympatico-adrenal system, which induces insulin resistance, hypertension and the other components of the metabolic syndrome. Available therapies for treatment of the metabolic syndrome (blockade of alpha- and beta-adrenergic receptors, insulin and insulin secretagogues) interfere with mechanisms, which must be considered compensatory. This explains why these therapies are disappointing in the long run. New therapeutic strategies based on the "selfish brain theory" will be discussed.

Use of DAC-Hours for Radiation Work Permit Suspension Guides and Validation of Respiratory Equipment Selection at the Savannah River Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hadlock, D.J.

Historically, the Savannah River Site, like many Department of Energy sites, has used some multiple of the expected Derived Air Concentration (DAC) of a radionuclide as a suspension guide for Radiological Work Permits (RWP) or validation of selected respiratory protection equipment. The term DAC expresses the concentration of a radionuclide in air, typically in mCi/cc. Even though the term DAC is derived from an intake of radioactivity (Annual Limit on Intake) that would result in defined estimated dose to a worker, knowing only the DAC value does not allow a worker's potential dose to be determined. Recently, the Savannah Rivemore » Site has converted to the use of DAC-hours for RWP suspension guides and respiratory equipment validation. The term DAC-hr takes into account not only the concentration of the radionuclide in air (DAC) but also the time the individual was exposed allowing an estimate of a worker's dose to be determined. The conversion to DAC-hrs resulted in four benefits to the radiation protection program without increasing the risk to workers; (1) consistency with the constant air monitor (CAM) alarm setpoint protocol; (2) consistency with Internal Dosimetry terminology; (3) an a priori determination of the potential risk to a worker; and (4) reduced complexity/error in field calculations. This paper outlines the justification for the conversion to DAC-hrs, the protocols used for field and count room calculations, and the implementation process utilized at the Savannah River Site« less

Physiological Disorders in Closed Environment-Grown Crops for Space Life Support

NASA Astrophysics Data System (ADS)

Wheeler, Raymond; Morrow, Robert

Crop production for life support systems in space will require controlled environments where temperature, humidity, CO2, and light might differ from natural environments where plants evolved. Physiological disorders, i.e., abnormal plant growth and development, can occur under these controlled environments. Among the most common of these disorders are Ca deficiency injuries such as leaf tipburn (e.g., lettuce), blossom-end-rot in fruits (e.g., tomato and pepper), and internal tissue necrosis in fruits or tubers (e.g., cucumber and potato). Increased Ca nutrition to the plants typically has little effect on these disorders, but slowing overall growth or providing better air circulation to increase transpiration can be effective. A second common disorder is oedema or intumescence, which appears as callus-like growth or galls on leaves (e.g., sweetpotato, potato, pepper, and tomato). This disorder can be reduced by increasing the near UV radiation ( 300-400 nm) to the plants. Leaf injury and necrosis can occur under long photoperiods (e.g., tomato, potato, and pepper) and at super-elevated (i.e., ¿ than 4000 mol mol-1) CO2 concentrations (e.g., soybean, potato, and radish), and these can be managed by reducing the photoperiod and CO2 concentration, respectively. Lack of blue light in the spectrum (e.g., under red LEDs or LPS lamps) can result in leggy growth and/or leaves lacking in chlorophyll (e.g., wheat, bean, and radish). Volatile organic compounds (VOCs), most commonly ethylene, can accumulate in tightly closed systems and result in a variety of negative responses. Most of these disorders can be mitigated by altering the environmental set-points or by using more resistant cultivars.

Traceable quantum sensing and metrology relied up a quantum electrical triangle principle

NASA Astrophysics Data System (ADS)

Fang, Yan; Wang, Hengliang; Yang, Xinju; Wei, Jingsong

2016-11-01

Hybrid quantum state engineering in quantum communication and imaging1-2 needs traceable quantum sensing and metrology, which are especially critical to quantum internet3 and precision measurements4 that are important across all fields of science and technology-. We aim to set up a mode of traceable quantum sensing and metrology. We developed a method by specially transforming an atomic force microscopy (AFM) and a scanning tunneling microscopy (STM) into a conducting atomic force microscopy (C-AFM) with a feedback control loop, wherein quantum entanglement enabling higher precision was relied upon a set-point, a visible light laser beam-controlled an interferometer with a surface standard at z axis, diffractometers with lateral standards at x-y axes, four-quadrant photodiode detectors, a scanner and its image software, a phase-locked pre-amplifier, a cantilever with a kHz Pt/Au conducting tip, a double barrier tunneling junction model, a STM circuit by frequency modulation and a quantum electrical triangle principle involving single electron tunneling effect, quantum Hall effect and Josephson effect5. The average and standard deviation result of repeated measurements on a 1 nm height local micro-region of nanomedicine crystal hybrid quantum state engineering surface and its differential pA level current and voltage (dI/dV) in time domains by using C-AFM was converted into an international system of units: Siemens (S), an indicated value 0.86×10-12 S (n=6) of a relative standard uncertainty was superior over a relative standard uncertainty reference value 2.3×10-10 S of 2012 CODADA quantized conductance6. It is concluded that traceable quantum sensing and metrology is emerging.

Homeostatic theory of obesity

PubMed Central

2015-01-01

Health is regulated by homeostasis, a property of all living things. Homeostasis maintains equilibrium at set-points using feedback loops for optimum functioning of the organism. Imbalances in homeostasis causing overweight and obesity are evident in more than 1 billion people. In a new theory, homeostatic obesity imbalance is attributed to a hypothesized ‘Circle of Discontent’, a system of feedback loops linking weight gain, body dissatisfaction, negative affect and over-consumption. The Circle of Discontent theory is consistent with an extensive evidence base. A four-armed strategy to halt the obesity epidemic consists of (1) putting a stop to victim-blaming, stigma and discrimination; (2) devalorizing the thin-ideal; (3) reducing consumption of energy-dense, low-nutrient foods and drinks; and (4) improving access to plant-based diets. If fully implemented, interventions designed to restore homeostasis have the potential to halt the obesity epidemic. PMID:28070357

Radiative human body cooling by nanoporous polyethylene textile.

PubMed

Hsu, Po-Chun; Song, Alex Y; Catrysse, Peter B; Liu, Chong; Peng, Yucan; Xie, Jin; Fan, Shanhui; Cui, Yi

2016-09-02

Thermal management through personal heating and cooling is a strategy by which to expand indoor temperature setpoint range for large energy saving. We show that nanoporous polyethylene (nanoPE) is transparent to mid-infrared human body radiation but opaque to visible light because of the pore size distribution (50 to 1000 nanometers). We processed the material to develop a textile that promotes effective radiative cooling while still having sufficient air permeability, water-wicking rate, and mechanical strength for wearability. We developed a device to simulate skin temperature that shows temperatures 2.7° and 2.0°C lower when covered with nanoPE cloth and with processed nanoPE cloth, respectively, than when covered with cotton. Our processed nanoPE is an effective and scalable textile for personal thermal management. Copyright © 2016, American Association for the Advancement of Science.

Temperature-dependent thermal conductivity of silicone-Al2O3 nanocomposites

NASA Astrophysics Data System (ADS)

Moreira, D. C.; Braga Junior, N. R.; Benevides, R. O.; Sphaier, L. A.; Nunes, L. C. S.

2015-11-01

This paper presents an experimental investigation of thermophysical properties of elastomeric nano-composites. Spherical alumina nanoparticles with a diameter of 150 nm were added to polydimethylsiloxane (PDMS), and batches of nanocomposites with different volume concentrations (up to 5 %) were produced. The thermal conductivity of the samples was acquired through the guarded heat flow meter method at nine temperature setpoints, ranging from 0 to 80 °C, and density measurements were carried out, in order to evaluate the composition of the samples. The results showed a significant increase in the thermal conductivity of PDMS with small additions of alumina nanoparticles. In addition, a notable linear decrease in conductivity was observed with increasing temperature. Finally, classical models were fitted to the experimental data and a discussion about the physical meaning of the adjusted parameters was carried out.

Plasma Viral Loads During Early HIV-1 Infection Are Similar in Subtype C– and Non-Subtype C–Infected African Seroconverters

PubMed Central

Campbell, Mary S.; Kahle, Erin M.; Celum, Connie; Lingappa, Jairam R.; Kapiga, Saidi; Mujugira, Andrew; Mugo, Nelly R.; Fife, Kenneth H.; Mullins, James I.; Baeten, Jared M.; Celum, Connie; Wald, Anna; Lingappa, Jairam; Baeten, Jared M.; Campbell, Mary S.; Corey, Lawrence; Coombs, Robert W.; Hughes, James P.; Magaret, Amalia; McElrath, M. Juliana; Morrow, Rhoda; Mullins, James I.; Coetzee, David; Fife, Kenneth; Were, Edwin; Essex, Max; Makhema, Joseph; Katabira, Elly; Ronald, Allan; Allen, Susan; Kayitenkore, Kayitesi; Karita, Etienne; Bukusi, Elizabeth; Cohen, Craig; Allen, Susan; Kanweka, William; Allen, Susan; Vwalika, Bellington; Kapiga, Saidi; Manongi, Rachel; Farquhar, Carey; John-Stewart, Grace; Kiarie, James; Allen, Susan; Inambao, Mubiana; Farm, Orange; Delany-Moretlwe, Sinead; Rees, Helen; de Bruyn, Guy; Gray, Glenda; McIntyre, James; Mugo, Nelly Rwamba

2013-01-01

Recent data suggest that infection with human immunodeficiency virus type 1 (HIV-1) subtype C results in prolonged high-level viremia (>5 log10 copies/mL) during early infection. We examined the relationship between HIV-1 subtype and plasma viremia among 153 African seroconverters. Mean setpoint viral loads were similar for C and non-C subtypes: 4.36 vs 4.42 log10 copies/mL (P = .61). The proportion of subtype C–infected participants with viral loads >5 log10 copies/mL was not greater than the proportion for those with non-C infection. Our data do not support the hypothesis that higher early viral load accounts for the rapid spread of HIV-1 subtype C in southern Africa. PMID:23315322

DOE Office of Scientific and Technical Information (OSTI.GOV)

March-Leuba, J.A.

Nuclear plants of the 21st century will employ higher levels of automation and fault tolerance to increase availability, reduce accident risk, and lower operating costs. Key developments in control algorithms, fault diagnostics, fault tolerance, and communication in a distributed system are needed to implement the fully automated plant. Equally challenging will be integrating developments in separate information and control fields into a cohesive system, which collectively achieves the overall goals of improved performance, safety, reliability, maintainability, and cost-effectiveness. Under the Nuclear Energy Research Initiative (NERI), the U. S. Department of Energy is sponsoring a project to address some of themore » technical issues involved in meeting the long-range goal of 21st century reactor control systems. This project, ''A New Paradigm for Automated Development Of Highly Reliable Control Architectures For Future Nuclear Plants,'' involves researchers from Oak Ridge National Laboratory, University of Tennessee, and North Carolina State University. This paper documents a research effort to develop methods for automated generation of control systems that can be traced directly to the design requirements. Our final goal is to allow the designer to specify only high-level requirements and stress factors that the control system must survive (e.g. a list of transients, or a requirement to withstand a single failure.) To this end, the ''control engine'' automatically selects and validates control algorithms and parameters that are optimized to the current state of the plant, and that have been tested under the prescribed stress factors. The control engine then automatically generates the control software from validated algorithms. Examples of stress factors that the control system must ''survive'' are: transient events (e.g., set-point changes, or expected occurrences such a load rejection,) and postulated component failures. These stress factors are specified by the designer and become a database of prescribed transients and component failures. The candidate control systems are tested, and their parameters optimized, for each of these stresses. Examples of high-level requirements are: response time less than xx seconds, or overshoot less than xx% ... etc. In mathematical terms, these types of requirements are defined as ''constraints,'' and there are standard mathematical methods to minimize an objective function subject to constraints. Since, in principle, any control design that satisfies all the above constraints is acceptable, the designer must also select an objective function that describes the ''goodness'' of the control design. Examples of objective functions are: minimize the number or amount of control motions, minimize an energy balance... etc.« less

Calibrating Physical Parameters in House Models Using Aggregate AC Power Demand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yannan; Stevens, Andrew J.; Lian, Jianming

For residential houses, the air conditioning (AC) units are one of the major resources that can provide significant flexibility in energy use for the purpose of demand response. To quantify the flexibility, the characteristics of all the houses need to be accurately estimated, so that certain house models can be used to predict the dynamics of the house temperatures in order to adjust the setpoints accordingly to provide demand response while maintaining the same comfort levels. In this paper, we propose an approach using the Reverse Monte Carlo modeling method and aggregate house models to calibrate the distribution parameters ofmore » the house models for a population of residential houses. Given the aggregate AC power demand for the population, the approach can successfully estimate the distribution parameters for the sensitive physical parameters based on our previous uncertainty quantification study, such as the mean of the floor areas of the houses.« less

Pretest analysis document for Test S-NH-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Owca, W.A.

This report documents the pretest analysis calculation completed with the RELAP5/MOD2/CY3601 code for Semiscale MOD-2C Test S-NH-1. The test will simulate the shear of a small diameter penetration of a cold leg, equivalent to 0.5% of the cold leg flow area. The high pressure injection system is assumed to be inoperative throughout the transient. The recovery procedure consists of latching open both steam generator ADV's while feeding with auxiliary feedwater, and accumulator operation. Recovery will be initiated upon a peak cladding temperature of 811 K (1000/sup 0/F). The test will be terminated when primary pressure has been reduced to themore » low pressure injection system setpoint of 1.38 MPa (200 psia). The calculated results indicate that the test objectives can be achieved and the proposed test scenario poses no threat to personnel or to plant integrity. 12 figs.« less

Homeostatic reinforcement learning for integrating reward collection and physiological stability.

PubMed

Keramati, Mehdi; Gutkin, Boris

2014-12-02

Efficient regulation of internal homeostasis and defending it against perturbations requires adaptive behavioral strategies. However, the computational principles mediating the interaction between homeostatic and associative learning processes remain undefined. Here we use a definition of primary rewards, as outcomes fulfilling physiological needs, to build a normative theory showing how learning motivated behaviors may be modulated by internal states. Within this framework, we mathematically prove that seeking rewards is equivalent to the fundamental objective of physiological stability, defining the notion of physiological rationality of behavior. We further suggest a formal basis for temporal discounting of rewards by showing that discounting motivates animals to follow the shortest path in the space of physiological variables toward the desired setpoint. We also explain how animals learn to act predictively to preclude prospective homeostatic challenges, and several other behavioral patterns. Finally, we suggest a computational role for interaction between hypothalamus and the brain reward system.

Tuning pathological brain oscillations with neurofeedback: a systems neuroscience framework

PubMed Central

Ros, Tomas; J. Baars, Bernard; Lanius, Ruth A.; Vuilleumier, Patrik

2014-01-01

Neurofeedback (NFB) is emerging as a promising technique that enables self-regulation of ongoing brain oscillations. However, despite a rise in empirical evidence attesting to its clinical benefits, a solid theoretical basis is still lacking on the manner in which NFB is able to achieve these outcomes. The present work attempts to bring together various concepts from neurobiology, engineering, and dynamical systems so as to propose a contemporary theoretical framework for the mechanistic effects of NFB. The objective is to provide a firmly neurophysiological account of NFB, which goes beyond traditional behaviorist interpretations that attempt to explain psychological processes solely from a descriptive standpoint whilst treating the brain as a “black box”. To this end, we interlink evidence from experimental findings that encompass a broad range of intrinsic brain phenomena: starting from “bottom-up” mechanisms of neural synchronization, followed by “top-down” regulation of internal brain states, moving to dynamical systems plus control-theoretic principles, and concluding with activity-dependent as well as homeostatic forms of brain plasticity. In support of our framework, we examine the effects of NFB in several brain disorders, including attention-deficit hyperactivity (ADHD) and post-traumatic stress disorder (PTSD). In sum, it is argued that pathological oscillations emerge from an abnormal formation of brain-state attractor landscape(s). The central thesis put forward is that NFB tunes brain oscillations toward a homeostatic set-point which affords an optimal balance between network flexibility and stability (i.e., self-organised criticality (SOC)). PMID:25566028

Micro-incubator for bacterial biosensing applications

NASA Astrophysics Data System (ADS)

Clasen, Estine; Land, Kevin; Joubert, Trudi-Heleen

2016-02-01

The presence of Escherichia coli (E. coli ) is a commonly used indicator micro-organism to determine whether water is safe for human consumption.1 This paper discusses the design of a micro-incubator that can be applied to concentrate bacteria prior to environmental water quality screening tests. High sensitivity and rapid test time is essential and there is a great need for these tests to be implemented on-site without the use of a laboratory infrastructure. In the light of these requirements, a mobile micro-incubator was designed, manufactured and characterised. A polydimethylsiloxane (PDMS) receptacle has been designed to house the 1-5 ml cell culture sample.2 A nano-silver printed electronics micro-heater has been designed to incubate the bacterial sample, with an array of temperature sensors implemented to accurately measure the sample temperature at various locations in the cell culture well. The micro-incubator limits the incubation temperature range to 37+/-3 °C in order to ensure near optimal growth of the bacteria at all times.3 The incubation time is adjustable between 30 minutes and 9 hours with a maximum rise time of 15 minutes to reach the set-point temperature. The surface area of the printed nano silver heating element is 500 mm2. Electrical and COMSOL Multiphysics simulations are included in order to give insight on micro-incubator temperature control. The design and characterization of this micro-incubator allows for further research in biosensing applications.

Subjective time runs faster under the influence of bright rather than dim light conditions during the forenoon.

PubMed

Morita, Takeshi; Fukui, Tomoe; Morofushi, Masayo; Tokura, Hiromi

2007-05-16

The study investigated if 6 h morning bright light exposure, compared with dim light exposure, could influence time sense (range: 5-15 s). Eight women served as participants. The participant entered a bioclimatic chamber at 10:00 h on the day before the test day, where an ambient temperature and relative humidity were controlled at 25 degrees C and 60%RH. She sat quietly in a sofa in 50 lx until 22:00 h, retired at 22:00 h and then slept in total darkness. She rose at 07:00 h the following morning and again sat quietly in a sofa till 13:00 h, either in bright (2500 lx) or dim light (50 lx), the order of light intensities between the two occasions being randomized. The time-estimation test was performed from 13:00 to 13:10 h in 200 lx. The participant estimated the time that had elapsed between two buzzers, ranging over 5-15 s, and inputting the estimate into a computer. The test was carried out separately upon each individual. Results showed that the participants estimated higher durations of the given time intervals after previous exposure to 6 h of bright rather than dim light. The finding is discussed in terms of different load errors (difference between the actual core temperature and its thermoregulatory set-point) following 6-h exposure to bright or dim light in the morning.

The impact of oxygen on the transcriptome of recombinant S. cerevisiae and P. pastoris - a comparative analysis.

PubMed

Baumann, Kristin; Dato, Laura; Graf, Alexandra B; Frascotti, Gianni; Dragosits, Martin; Porro, Danilo; Mattanovich, Diethard; Ferrer, Pau; Branduardi, Paola

2011-05-09

Saccharomyces cerevisiae and Pichia pastoris are two of the most relevant microbial eukaryotic platforms for the production of recombinant proteins. Their known genome sequences enabled several transcriptomic profiling studies under many different environmental conditions, thus mimicking not only perturbations and adaptations which occur in their natural surroundings, but also in industrial processes. Notably, the majority of such transcriptome analyses were performed using non-engineered strains.In this comparative study, the gene expression profiles of S. cerevisiae and P. pastoris, a Crabtree positive and Crabtree negative yeast, respectively, were analyzed for three different oxygenation conditions (normoxic, oxygen-limited and hypoxic) under recombinant protein producing conditions in chemostat cultivations. The major differences in the transcriptomes of S. cerevisiae and P. pastoris were observed between hypoxic and normoxic conditions, where the availability of oxygen strongly affected ergosterol biosynthesis, central carbon metabolism and stress responses, particularly the unfolded protein response. Steady state conditions under low oxygen set-points seemed to perturb the transcriptome of S. cerevisiae to a much lesser extent than the one of P. pastoris, reflecting the major tolerance of the baker's yeast towards oxygen limitation, and a higher fermentative capacity. Further important differences were related to Fab production, which was not significantly affected by oxygen availability in S. cerevisiae, while a clear productivity increase had been previously reported for hypoxically grown P. pastoris. The effect of three different levels of oxygen availability on the physiology of P. pastoris and S. cerevisiae revealed a very distinct remodelling of the transcriptional program, leading to novel insights into the different adaptive responses of Crabtree negative and positive yeasts to oxygen availability. Moreover, the application of such comparative genomic studies to recombinant hosts grown in different environments might lead to the identification of key factors for efficient protein production.

Hydrogen and Oxygen Gas Monitoring System Design and Operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee C. Cadwallader; Kevin G. DeWall; J. Stephen Herring

2007-06-01

This paper describes pertinent design practices of selecting types of monitors, monitor unit placement, setpoint selection, and maintenance considerations for gas monitors. While hydrogen gas monitors and enriched oxygen atmosphere monitors as they would be needed for hydrogen production experiments are the primary focus of this paper, monitors for carbon monoxide and carbon dioxide are also discussed. The experiences of designing, installing, and calibrating gas monitors for a laboratory where experiments in support of the DOE Nuclear Hydrogen Initiative (NHI) are described along with codes, standards, and regulations for these monitors. Information from the literature about best operating practices ismore » also presented. The NHI program has two types of activities. The first, near-term activity is laboratory and pilot-plant experimentation with different processes in the kilogram per day scale to select the most promising types of processes for future applications of hydrogen production. Prudent design calls for indoor gas monitors to sense any hydrogen leaks within these laboratory rooms. The second, longer-term activity is the prototype, or large-scale plants to produce tons of hydrogen per day. These large, outdoor production plants will require area (or “fencepost”) monitoring of hydrogen gas leaks. Some processes will have oxygen production with hydrogen production, and any oxygen releases are also safety concerns since oxygen gas is the strongest oxidizer. Monitoring of these gases is important for personnel safety of both indoor and outdoor experiments. There is some guidance available about proper placement of monitors. The fixed point, stationary monitor can only function if the intruding gas contacts the monitor. Therefore, monitor placement is vital to proper monitoring of the room or area. Factors in sensor location selection include: indoor or outdoor site, the location and nature of potential vapor/gas sources, chemical and physical data of the gases or vapors, liquids with volatility need sensors near the potential sources of release, nature and concentration of gas releases, natural and mechanical ventilation, detector installation locations not vulnerable to mechanical or water damage from normal operations, and locations that lend themselves to convenient maintenance and calibration. The guidance also states that sensors should be located in all areas where hazardous accumulations of gas may occur. Such areas might not be close to release points but might be areas with restricted air movement. Heavier than air gases are likely to accumulate in pits, trenches, drains, and other low areas. Lighter than air gases are more likely to accumulate in overhead spaces, above drop ceilings, etc. In general, sensors should be located close to any potential sources of major release of gas. The paper gives data on monitor sensitivity and expected lifetimes to support the monitor selection process. Proper selection of indoor and outdoor locations for monitors is described, accounting for the vapor densities of hydrogen and oxygen. The latest information on monitor alarm setpoint selection is presented. Typically, monitors require recalibration at least every six months, or more frequently for inhospitable locations, so ready access to the monitors is an important issue to consider in monitor siting. Gas monitors, depending on their type, can be susceptible to blockages of the detector element (i.e., dus« less

Anti-inflammatory salicylate treatment alters the metabolic adaptations to lactation in dairy cattle

PubMed Central

Farney, Jaymelynn K.; Mamedova, Laman K.; Coetzee, Johann F.; KuKanich, Butch; Sordillo, Lorraine M.; Stoakes, Sara K.; Minton, J. Ernest; Hollis, Larry C.

2013-01-01

Adapting to the lactating state requires metabolic adjustments in multiple tissues, especially in the dairy cow, which must meet glucose demands that can exceed 5 kg/day in the face of negligible gastrointestinal glucose absorption. These challenges are met through the process of homeorhesis, the alteration of metabolic setpoints to adapt to a shift in physiological state. To investigate the role of inflammation-associated pathways in these homeorhetic adaptations, we treated cows with the nonsteroidal anti-inflammatory drug sodium salicylate (SS) for the first 7 days of lactation. Administration of SS decreased liver TNF-α mRNA and marginally decreased plasma TNF-α concentration, but plasma eicosanoids and liver NF-κB activity were unaltered during treatment. Despite the mild impact on these inflammatory markers, SS clearly altered metabolic function. Plasma glucose concentration was decreased by SS, but this was not explained by a shift in hepatic gluconeogenic gene expression or by altered milk lactose secretion. Insulin concentrations decreased in SS-treated cows on day 7 compared with controls, which was consistent with the decline in plasma glucose concentration. The revised quantitative insulin sensitivity check index (RQUICKI) was then used to assess whether altered insulin sensitivity may have influenced glucose utilization rate with SS. The RQUICKI estimate of insulin sensitivity was significantly elevated by SS on day 7, coincident with the decline in plasma glucose concentration. Salicylate prevented postpartum insulin resistance, likely causing excessive glucose utilization in peripheral tissues and hypoglycemia. These results represent the first evidence that inflammation-associated pathways are involved in homeorhetic adaptations to lactation. PMID:23678026

High-speed adaptive contact-mode atomic force microscopy imaging with near-minimum-force

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Juan; Zou, Qingze, E-mail: qzzou@rci.rutgers.edu

In this paper, an adaptive contact-mode imaging approach is proposed to replace the traditional contact-mode imaging by addressing the major concerns in both the speed and the force exerted to the sample. The speed of the traditional contact-mode imaging is largely limited by the need to maintain precision tracking of the sample topography over the entire imaged sample surface, while large image distortion and excessive probe-sample interaction force occur during high-speed imaging. In this work, first, the image distortion caused by the topography tracking error is accounted for in the topography quantification. Second, the quantified sample topography is utilized inmore » a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line topography is integrated to the topography feeedback loop to enhance the sample topography tracking. The proposed approach is demonstrated and evaluated through imaging a calibration sample of square pitches at both high speeds (e.g., scan rate of 75 Hz and 130 Hz) and large sizes (e.g., scan size of 30 μm and 80 μm). The experimental results show that compared to the traditional constant-force contact-mode imaging, the imaging speed can be increased by over 30 folds (with the scanning speed at 13 mm/s), and the probe-sample interaction force can be reduced by more than 15% while maintaining the same image quality.« less

The Empower project - a new way of assessing and monitoring test comparability and stability.

PubMed

De Grande, Linde A C; Goossens, Kenneth; Van Uytfanghe, Katleen; Stöckl, Dietmar; Thienpont, Linda M

2015-07-01

Manufacturers and laboratories might benefit from using a modern integrated tool for quality management/assurance. The tool should not be confounded by commutability issues and focus on the intrinsic analytical quality and comparability of assays as performed in routine laboratories. In addition, it should enable monitoring of long-term stability of performance, with the possibility to quasi "real-time" remedial action. Therefore, we developed the "Empower" project. The project comprises four pillars: (i) master comparisons with panels of frozen single-donation samples, (ii) monitoring of patient percentiles and (iii) internal quality control data, and (iv) conceptual and statistical education about analytical quality. In the pillars described here (i and ii), state-of-the-art as well as biologically derived specifications are used. In the 2014 master comparisons survey, 125 laboratories forming 8 peer groups participated. It showed not only good intrinsic analytical quality of assays but also assay biases/non-comparability. Although laboratory performance was mostly satisfactory, sometimes huge between-laboratory differences were observed. In patient percentile monitoring, currently, 100 laboratories participate with 182 devices. Particularly, laboratories with a high daily throughput and low patient population variation show a stable moving median in time with good between-instrument concordance. Shifts/drifts due to lot changes are sometimes revealed. There is evidence that outpatient medians mirror the calibration set-points shown in the master comparisons. The Empower project gives manufacturers and laboratories a realistic view on assay quality/comparability as well as stability of performance and/or the reasons for increased variation. Therefore, it is a modern tool for quality management/assurance toward improved patient care.

Complete nutrient recovery from source-separated urine by nitrification and distillation.

PubMed

Udert, K M; Wächter, M

2012-02-01

In this study we present a method to recover all nutrients from source-separated urine in a dry solid by combining biological nitrification with distillation. In a first process step, a membrane-aerated biofilm reactor was operated stably for more than 12 months, producing a nutrient solution with a pH between 6.2 and 7.0 (depending on the pH set-point), and an ammonium to nitrate ratio between 0.87 and 1.15 gN gN(-1). The maximum nitrification rate was 1.8 ± 0.3 gN m(-2) d(-1). Process stability was achieved by controlling the pH via the influent. In the second process step, real nitrified urine and synthetic solutions were concentrated in lab-scale distillation reactors. All nutrients were recovered in a dry powder except for some ammonia (less than 3% of total nitrogen). We estimate that the primary energy demand for a simple nitrification/distillation process is four to five times higher than removing nitrogen and phosphorus in a conventional wastewater treatment plant and producing the equivalent amount of phosphorus and nitrogen fertilizers. However, the primary energy demand can be reduced to values very close to conventional treatment, if 80% of the water is removed with reverse osmosis and distillation is operated with vapor compression. The ammonium nitrate content of the solid residue is below the limit at which stringent EU safety regulations for fertilizers come into effect; nevertheless, we propose some additional process steps that will increase the thermal stability of the solid product. Copyright © 2011 Elsevier Ltd. All rights reserved.

A hedging point strategy--balancing effluent quality, economy and robustness in the control of wastewater treatment plants.

PubMed

Ingildsen, P; Olsson, G; Yuan, Z

2002-01-01

An operational space map is an efficient tool to compare a large number of operational strategies to find an optimal choice of setpoints based on a multicriterion. Typically, such a multicriterion includes a weighted sum of cost of operation and effluent quality. Due to the relative high cost of aeration such a definition of optimality result in a relatively high fraction of the effluent total nitrogen in the form of ammonium. Such a strategy may however introduce a risk into operation because a low degree of ammonium removal leads to a low amount of nitrifiers. This in turn leads to a reduced ability to reject event disturbances, such as large variations in the ammonium load, drop in temperature, the presence of toxic/inhibitory compounds in the influent etc. Hedging is a risk minimisation tool, with the aim to "reduce one's risk of loss on a bet or speculation by compensating transactions on the other side" (The Concise Oxford Dictionary (1995)). In wastewater treatment plant operation hedging can be applied by choosing a higher level of ammonium removal to increase the amount of nitrifiers. This is a sensible way to introduce disturbance rejection ability into the multi criterion. In practice, this is done by deciding upon an internal effluent ammonium criterion. In some countries such as Germany, a separate criterion already applies to the level of ammonium in the effluent. However, in most countries the effluent criterion applies to total nitrogen only. In these cases, an internal effluent ammonium criterion should be selected in order to secure proper disturbance rejection ability.

Renal Response to Chronic Centrifugation in Rats

NASA Technical Reports Server (NTRS)

Ortiz, Rudy M.; Wang, T. J.; Corbin, B. J.; Wade, C. E.; Hargens, Alan R. (Technical Monitor)

1996-01-01

Previously reported effects of chronic centrifugation on renal function in mammals are contradictory. The present study was conducted as an effort to provide a comprehensive analysis of renal response to chronic centrifugation (12 days at +2 Gz). Sixteen male Sprague-Dawley rats (210-230 g) were used: eight centrifuged (EC) and eight off centrifuge controls (OCC). During centrifugation EC had lower body weight and food consumption. EC showed a decrease (72%) in water intake for the first two days (T1 and T2) followed by significant increases from T4-T6. EC urine output increased two-fold over the first four days, returning to baseline by T9. EC urea excretion was elevated on T3 through T5. Creatinine, Na(+), K(+), and osmolar excretion were lower than OCC over the last four days of the study. Assuming constant plasma osmolarity and creatinine levels, EC free water clearance (C(sub H2O)) was elevated significantly on T4 when the peak urine output was exhibited. EC also had a greater C(sub H2O) over the last four days, associated with a significantly lower osmolar clearance and GFR. The initial diuresis exhibited during centrifugation can be attributed to a reduced water resorption and increased urea excretion. This diuresis was mediated independent of changes in GFR over the first eight days. However, differences in excretion seen after eight days of centrifugation are probably GFR mediated which would imply animals established a new homeostatic setpoint by that time. Centrifugation elicites an acute alteration in fluid homeostasis followed by adaptation within a week.

High-speed adaptive contact-mode atomic force microscopy imaging with near-minimum-force.

PubMed

Ren, Juan; Zou, Qingze

2014-07-01

In this paper, an adaptive contact-mode imaging approach is proposed to replace the traditional contact-mode imaging by addressing the major concerns in both the speed and the force exerted to the sample. The speed of the traditional contact-mode imaging is largely limited by the need to maintain precision tracking of the sample topography over the entire imaged sample surface, while large image distortion and excessive probe-sample interaction force occur during high-speed imaging. In this work, first, the image distortion caused by the topography tracking error is accounted for in the topography quantification. Second, the quantified sample topography is utilized in a gradient-based optimization method to adjust the cantilever deflection set-point for each scanline closely around the minimal level needed for maintaining stable probe-sample contact, and a data-driven iterative feedforward control that utilizes a prediction of the next-line topography is integrated to the topography feeedback loop to enhance the sample topography tracking. The proposed approach is demonstrated and evaluated through imaging a calibration sample of square pitches at both high speeds (e.g., scan rate of 75 Hz and 130 Hz) and large sizes (e.g., scan size of 30 μm and 80 μm). The experimental results show that compared to the traditional constant-force contact-mode imaging, the imaging speed can be increased by over 30 folds (with the scanning speed at 13 mm/s), and the probe-sample interaction force can be reduced by more than 15% while maintaining the same image quality.

Magnesium deficiency induces anxiety and HPA axis dysregulation: Modulation by therapeutic drug treatment

PubMed Central

Sartori, S.B.; Whittle, N.; Hetzenauer, A.; Singewald, N.

2012-01-01

Preclinical and some clinical studies suggest a relationship between perturbation in magnesium (Mg2+) homeostasis and pathological anxiety, although the underlying mechanisms remain largely unknown. Since there is evidence that Mg2+ modulates the hypothalamic-pituitary adrenal (HPA) axis, we tested whether enhanced anxiety-like behaviour can be reliably elicited by dietary Mg2+ deficiency and whether Mg2+ deficiency is associated with altered HPA axis function. Compared with controls, Mg2+ deficient mice did indeed display enhanced anxiety-related behaviour in a battery of established anxiety tests. The enhanced anxiety-related behaviour of Mg2+ deficient mice was sensitive to chronic desipramine treatment in the hyponeophagia test and to acute diazepam treatment in the open arm exposure test. Mg2+ deficiency caused an increase in the transcription of the corticotropin releasing hormone in the paraventricular hypothalamic nucleus (PVN), and elevated ACTH plasma levels, pointing to an enhanced set-point of the HPA axis. Chronic treatment with desipramine reversed the identified abnormalities of the stress axis. Functional mapping of neuronal activity using c-Fos revealed hyper-excitability in the PVN of anxious Mg2+ deficient mice and its normalisation through diazepam treatment. Overall, the present findings demonstrate the robustness and validity of the Mg2+ deficiency model as a mouse model of enhanced anxiety, showing sensitivity to treatment with anxiolytics and antidepressants. It is further suggested that dysregulations in the HPA axis may contribute to the hyper-emotionality in response to dietary induced hypomagnesaemia. This article is part of a Special Issue entitled ‘Anxiety and Depression’. PMID:21835188

IDO2 in Immunomodulation and Autoimmune Disease

PubMed Central

Prendergast, George C.; Metz, Richard; Muller, Alexander J.; Merlo, Lauren M. F.; Mandik-Nayak, Laura

2014-01-01

IDO2 is a relative of IDO1 implicated in tryptophan catabolism and immune modulation but its specific contributions to normal physiology and pathophysiology are not known. Evolutionary genetic studies suggest that IDO2 has a unique function ancestral to IDO1. In mice, IDO2 gene deletion does not appreciably affect embryonic development or hematopoiesis, but it leads to defects in allergic or autoimmune responses and in the ability of IDO1 to influence the generation of T regulatory cells. Gene expression studies indicate that IDO2 is a basally and more narrowly expressed gene than IDO1 and that IDO2 is uniquely regulated by AhR, which serves as a physiological receptor for the tryptophan catabolite kynurenine. In the established KRN transgenic mouse model of rheumatoid arthritis, where IDO1 gene deletion has no effect, IDO2 deletion selectively blunts responses to autoantigen but has no effect on responses to neoantigen challenge. In human populations, natural variations in IDO2 gene sequence that attenuate enzymatic activity have been reported to influence brain cancer control and adaptive immune responses to the IDO2 protein itself, consistent with the concept that IDO2 is involved in shaping immune tolerance in human beings. Biochemical and pharmacological studies provide further evidence of differences in IDO2 enzymology and function relative to IDO1. We suggest that IDO2 may act in a distinct manner from IDO1 as a set-point for tolerance to “altered-self” antigens along the self-non-self continuum where immune challenges from cancer and autoimmunity may arise. PMID:25477879

IDO2 in Immunomodulation and Autoimmune Disease.

PubMed

Prendergast, George C; Metz, Richard; Muller, Alexander J; Merlo, Lauren M F; Mandik-Nayak, Laura

2014-01-01

IDO2 is a relative of IDO1 implicated in tryptophan catabolism and immune modulation but its specific contributions to normal physiology and pathophysiology are not known. Evolutionary genetic studies suggest that IDO2 has a unique function ancestral to IDO1. In mice, IDO2 gene deletion does not appreciably affect embryonic development or hematopoiesis, but it leads to defects in allergic or autoimmune responses and in the ability of IDO1 to influence the generation of T regulatory cells. Gene expression studies indicate that IDO2 is a basally and more narrowly expressed gene than IDO1 and that IDO2 is uniquely regulated by AhR, which serves as a physiological receptor for the tryptophan catabolite kynurenine. In the established KRN transgenic mouse model of rheumatoid arthritis, where IDO1 gene deletion has no effect, IDO2 deletion selectively blunts responses to autoantigen but has no effect on responses to neoantigen challenge. In human populations, natural variations in IDO2 gene sequence that attenuate enzymatic activity have been reported to influence brain cancer control and adaptive immune responses to the IDO2 protein itself, consistent with the concept that IDO2 is involved in shaping immune tolerance in human beings. Biochemical and pharmacological studies provide further evidence of differences in IDO2 enzymology and function relative to IDO1. We suggest that IDO2 may act in a distinct manner from IDO1 as a set-point for tolerance to "altered-self" antigens along the self-non-self continuum where immune challenges from cancer and autoimmunity may arise.

Perceptual evaluation of visual alerts in surveillance videos

NASA Astrophysics Data System (ADS)

Rogowitz, Bernice E.; Topkara, Mercan; Pfeiffer, William; Hampapur, Arun

2015-03-01

Visual alerts are commonly used in video monitoring and surveillance systems to mark events, presumably making them more salient to human observers. Surprisingly, the effectiveness of computer-generated alerts in improving human performance has not been widely studied. To address this gap, we have developed a tool for simulating different alert parameters in a realistic visual monitoring situation, and have measured human detection performance under conditions that emulated different set-points in a surveillance algorithm. In the High-Sensitivity condition, the simulated alerts identified 100% of the events with many false alarms. In the Lower-Sensitivity condition, the simulated alerts correctly identified 70% of the targets, with fewer false alarms. In the control condition, no simulated alerts were provided. To explore the effects of learning, subjects performed these tasks in three sessions, on separate days, in a counterbalanced, within subject design. We explore these results within the context of cognitive models of human attention and learning. We found that human observers were more likely to respond to events when marked by a visual alert. Learning played a major role in the two alert conditions. In the first session, observers generated almost twice as many False Alarms as in the No-Alert condition, as the observers responded pre-attentively to the computer-generated false alarms. However, this rate dropped equally dramatically in later sessions, as observers learned to discount the false cues. Highest observer Precision, Hits/(Hits + False Alarms), was achieved in the High Sensitivity condition, but only after training. The successful evaluation of surveillance systems depends on understanding human attention and performance.

Waste retrieval sluicing system data acquisition system acceptance test report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bevins, R.R.

1998-07-31

This document describes the test procedure for the Project W-320 Tank C-106 Sluicing Data Acquisition System (W-320 DAS). The Software Test portion will test items identified in the WRSS DAS System Description (SD), HNF-2115. Traceability to HNF-2115 will be via a reference that follows in parenthesis, after the test section title. The Field Test portion will test sensor operability, analog to digital conversion, and alarm setpoints for field instrumentation. The W-320 DAS supplies data to assist thermal modeling of tanks 241-C-106 and 241-AY-102. It is designed to be a central repository for information from sources that would otherwise have tomore » be read, recorded, and integrated manually. Thus, completion of the DAS requires communication with several different data collection devices and output to a usable PC data formats. This test procedure will demonstrate that the DAS functions as required by the project requirements stated in Section 3 of the W-320 DAS System Description, HNF-2115.« less

The use KPI's to determine the waste in production process

NASA Astrophysics Data System (ADS)

Borsos, G.; Iacob, C. C.; Calefariu, G.

2016-11-01

In theory and practice of management is well-known Lean approach about forms of waste from production processes (Muda) and the method VSM (Value Stream Map), one of the most effective methods for determining the activities generating value within industrial companies. It is also obvious concern of the specialists for performance measurement regardless of purview of the organizations. The literature review has shown that the link between performance indicators and the objectives of the companies is researched in detail. However, the correlation between indicators and the forms of waste that generate deviations from the setpoints is rather nature practical and it depends on the talent and managerial skills of those directing production processes. The paper presents the results of a applied study, performed by the authors, through which it was has sought to will create a system of performance indicators specific to manufacturing activity that to be a useful tool to quantify the losses and to determining ways to improve default losses.

Definition and means of maintaining the supply ventilation system seismic shutdown portion of the PFP safety envelope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keck, R.D.

1997-01-21

The purpose of this document is to record the technical evaluation of the Limiting Condition for Operation (LCO) described in the Plutonium Finishing Plant (PFP) Operational Safety Requirements, WHC-SD-CP-OSR- 010, Rev. 0. Kay 1994, Section 3.2.3, `Supply Ventilation System Seismic Shutdown.` This document, with its appendices, provides the following: 1. The system functional requirements for determining system operability (Section 3). 2. Evaluations of equipment to determine the safety boundary for the system (Section 4). 3. A list of annotated drawings which show the safety envelope boundaries (Appendix C). 4. A list of the safety envelope equipment (Appendix B). 5. Functionalmore » requirements for the individual safety envelope equipment, including appropriate setpoints and process parameters (Section 4.1). 6. A list of the operational, maintenance and surveillance procedures necessary to operate and maintain the system equipment within the safety envelope (Sections 5 and 6 and Appendix A).« less

Experimental evaluation of automotive air-conditioning using HFC-134a and HC-134a

NASA Astrophysics Data System (ADS)

Nasution, Henry; Zainudin, Muhammad Amir; Aziz, Azhar Abdul; Latiff, Zulkarnain Abdul; Perang, Mohd Rozi Mohd; Rahman, Abd Halim Abdul

2012-06-01

An experimental study to evaluate the energy consumption of an automotive air conditioning is presented. In this study, these refrigerants will be tested using the experimental rig which simulated the actual cars as a cabin complete with a cooling system component of the actual car that is as the blower, evaporator, condenser, radiators, electric motor, which acts as a vehicle engine, and then the electric motor will operate the compressor using a belt and pulley system, as well as to the alternator will recharge the battery. The compressor working with the fluids HFC-134a and HC-134a and has been tested varying the speed in the range 1000, 1500, 2000 and 2500 rpm. The measurements taken during the one hour experimental periods at 2-minutes interval times for temperature setpoint of 20°C with internal heat loads 0, 500, 700 and 1000 W. The final results of this study show an overall better energy consumption of the HFC-134a compared with the HC-134a.

Transcriptional regulation of PIN genes by FOUR LIPS and MYB88 during Arabidopsis root gravitropism.

PubMed

Wang, Hong-Zhe; Yang, Ke-Zhen; Zou, Jun-Jie; Zhu, Ling-Ling; Xie, Zi Dian; Morita, Miyo Terao; Tasaka, Masao; Friml, Jiří; Grotewold, Erich; Beeckman, Tom; Vanneste, Steffen; Sack, Fred; Le, Jie

2015-11-18

PIN proteins are auxin export carriers that direct intercellular auxin flow and in turn regulate many aspects of plant growth and development including responses to environmental changes. The Arabidopsis R2R3-MYB transcription factor FOUR LIPS (FLP) and its paralogue MYB88 regulate terminal divisions during stomatal development, as well as female reproductive development and stress responses. Here we show that FLP and MYB88 act redundantly but differentially in regulating the transcription of PIN3 and PIN7 in gravity-sensing cells of primary and lateral roots. On the one hand, FLP is involved in responses to gravity stimulation in primary roots, whereas on the other, FLP and MYB88 function complementarily in establishing the gravitropic set-point angles of lateral roots. Our results support a model in which FLP and MYB88 expression specifically determines the temporal-spatial patterns of PIN3 and PIN7 transcription that are closely associated with their preferential functions during root responses to gravity.

Potassium: friend or foe?

PubMed

Rodan, Aylin R

2017-07-01

The kidney plays an essential role in maintaining homeostasis of ion concentrations in the blood. Because the concentration gradient of potassium across the cell membrane is a key determinant of the membrane potential of cells, even small deviations in serum potassium level from the normal setpoint can lead to severe muscle dysfunction, resulting in respiratory failure and cardiac arrest. Less severe hypo- and hyperkalemia are also associated with morbidity and mortality across various patient populations. In addition, deficiencies in potassium intake have been associated with hypertension and adverse cardiovascular and renal outcomes, likely due in part to the interrelated handling of sodium and potassium by the kidney. Here, data on the beneficial effects of potassium on blood pressure and cardiovascular and renal outcomes will be reviewed, along with the physiological basis for these effects. In some patient populations, however, potassium excess is deleterious. Risk factors for the development of hyperkalemia will be reviewed, as well as the risks and benefits of existing and emerging therapies for hyperkalemia.

Laser bandwidth interlock capable of single pulse detection and rejection

DOEpatents

Armstrong, James P; Telford, Steven James; Lanning, Rodney Kay; Bayramian, Andrew James

2012-10-09

A pulse of laser light is switched out of a pulse train and spatially dispersed into its constituent wavelengths. The pulse is collimated to a suitable size and then diffracted by high groove density multilayer dielectric gratings. This imparts a different angle to each individual wavelength so that, when brought to the far field with a lens, the colors have spread out in a linear arrangement. The distance between wavelengths (resolution) can be tailored for the specific laser and application by altering the number of times the beam strikes the diffraction gratings, the groove density of the gratings and the focal length of the lens. End portions of the linear arrangement are each directed to a respective detector, which converts the signal to a 1 if the level meets a set-point, and a 0 if the level does not. If both detectors produces a 1, then the pulse train is allowed to propagate into an optical system.

Homeostatic reinforcement learning for integrating reward collection and physiological stability

PubMed Central

Keramati, Mehdi; Gutkin, Boris

2014-01-01

Efficient regulation of internal homeostasis and defending it against perturbations requires adaptive behavioral strategies. However, the computational principles mediating the interaction between homeostatic and associative learning processes remain undefined. Here we use a definition of primary rewards, as outcomes fulfilling physiological needs, to build a normative theory showing how learning motivated behaviors may be modulated by internal states. Within this framework, we mathematically prove that seeking rewards is equivalent to the fundamental objective of physiological stability, defining the notion of physiological rationality of behavior. We further suggest a formal basis for temporal discounting of rewards by showing that discounting motivates animals to follow the shortest path in the space of physiological variables toward the desired setpoint. We also explain how animals learn to act predictively to preclude prospective homeostatic challenges, and several other behavioral patterns. Finally, we suggest a computational role for interaction between hypothalamus and the brain reward system. DOI: http://dx.doi.org/10.7554/eLife.04811.001 PMID:25457346

Low-Pressure Generator Makes Cleanrooms Cleaner

NASA Technical Reports Server (NTRS)

2005-01-01

Scientists at NASA's Kennedy Space Center work in cleanrooms: laboratories with high degrees of cleanliness provided by strict control of particles such as dust, lint, or human skin. They are contaminant-free facilities, where the air is repeatedly filtered, and surfaces are smooth to prevent particles from getting lodged. Technicians working in these environments wear specially designed cleanroom "bunny suits" and booties over their street clothes, as well as gloves and face masks to avoid any contamination that may be imparted from the outside world. Even normal paper is not allowed in cleanrooms, only cleanroom low-particulate paper. These are sensitive environments where precision work, like the production of silicon chips or hard disk drives, is performed. Often in cleanrooms, positive air pressure is used to force particles outside of the isolated area. The air pressure in the Kennedy cleanrooms is monitored using high-accuracy, low-differential pressure transducers that require periodic calibration. Calibration of the transducers is a tricky business. In prior years, the analysis was performed by sending the transducers to the Kennedy Standards Laboratory, where a very expensive cross-floated, labor- intensive, dead-weight test was conducted. In the early 1990s, scientists at Kennedy determined to develop a technique and find equipment to perform qualification testing on new low-differential pressure transducers in an accurate, cost-effective manner onsite, without requiring an environmentally controlled room. They decided to use the highly accurate, cost-effective Setra Model C264 as the test transducer. For qualification testing of the Setra, though, a portable, lower-cost calibrator was needed that could control the differential pressure to a high degree of resolution and transfer the accuracy of the Standards Laboratory testing to the qualification testing. The researchers decided that, to generate the low-differential pressure setpoints needed for qualification testing, very small gas volume changes could be made against the test article, and a corresponding pressure change would be detected by a pressure standard. This allowed the researchers to recreate cleanroom air pressure settings without the use of a cleanroom. Thus was born the low-differential pressure generator. In 1993, a prototype was developed using a pair of PVC tanks, a volume controller, and a 1-pound-per-square-inch pressure standard. By 1995, the prototype was perfected into the unit that is still used today.

The MSFC Program Control Development Program

NASA Technical Reports Server (NTRS)

1994-01-01

It is the policy of the Marshall Space Flight Center (MSFC) that employees be given the opportunity to develop their individual skills and realize their full potential consistent with their selected career path and with the overall Center's needs and objectives. The MSFC Program Control Development Program has been designed to assist individuals who have selected Program Control or Program Analyst Program Control as a career path to achieve their ultimate career goals. Individuals selected to participate in the MSFC Program Control Development Program will be provided with development training in the various Program Control functional areas identified in the NASA Program Control Model. The purpose of the MSFC Program Control Development Program is to develop individual skills in the various Program Control functions by on-the-job and classroom instructional training on the various systems, tools, techniques, and processes utilized in these areas.

Worms on the International Space Station

NASA Technical Reports Server (NTRS)

Szewczyk, Nate; Kirven-Brooks, Melissa; Conley, Cassie

2002-01-01

C. elegans was proposed as a model system for space biology studies in 1991 and has since flown on STS-42, STS-76, and STS-95. Data obtained from these flights have confirmed that C. elegans requires adequate in flight oxygenation and displays an increased rate of mutation, much like other organisms in space. Unlike vertebrates, C. elegans has been observed to successfully complete two continuous full life cycles in space without gross developmental abnormalities. These observations, could with the utility of C. elegans as a terrestrial, fully sequenced, model system make C. elegans a good candidate for long term research onboard the International Space Station (ISS). We are currently working on technology to support biological studies aboard the ISS. A component of this effort is in the development of the Space Station Biological Research Program (SSBRP) Incubator which will be able to house organisms at a constant temperature setpoint ranging from 4deg C to 45deg C. The SSBRP Incubator provides air exchange, power, data and video ports and, when placed in the collaborative NASA/NASDA 2.5M centrifuge rotor, will be capable of providing a lg gravity control. Current plans for validation of the Incubator include video monitoring and periodic sampling of C. elegans in the Incubator onboard the ISS. Once returned to earth, samples will be distributed for analysis via a specimen sharing plan and analyzed for gene expression and other parameters of growth and development in space flight. These data should provide the C. elegans research community with a baseline from which to propose studies for future flights. We have also been developing an appropriate method of culturing C. elegans in liquid media in order to remove the need for the crew to assure that strains are properly fed. Currently, we are growing strains in the chemically defined, axenic, media developed by Dr. Nancy Lu. Wild-type animals complete multiple generations and appear generally healthy after being grown in unchanged media for a minimum of three to four weeks. To assure proper oxygenation we have chosen to grow animals in ten milliliter OptiCells(TradeMark). The choice of the OptiCell(TradeMark) also allows for automation of culturing as demonstrated for cell cultures grown in the OptiCell(TradeMark). Arrangements have been made for the liquid media to be commercially produced by Mediatech, Inc. and OptiCells(TradeMark) are available from BioCrystal Ltd.

Dermal Aged and Fetal Fibroblasts Realign in Response to Mechanical Strain

NASA Technical Reports Server (NTRS)

Sawyer, Christine; Grymes, Rose; Alvarez, Teresa (Technical Monitor)

1994-01-01

Integrins specifically recognize and bind extracellular matrix components, providing physical anchor points and functional setpoints. Focal adhesion complexes, containing integrin and cytoskeletal proteins, are potential mechanoreceptors, poised to distribute applied forces through the cytoskeleton. Pursuing the hypothesis that cells both perceive and respond to external force, we applied a stretch/relaxation regimen to normal human fetal and aged dermal fibroblast monolayers cultured on flexible membranes. The frequency and magnitude of the applied force is precisely controlled by the Flexercell Unit(Trademark). A protocol of stretch (20% elongation of the monolayer) at a frequency of 6 cycles/min caused a progressive change from a randomly distributed pattern of cells to a symmetric, radial distribution with cells aligned parallel to the applied force. We have coined the term 'orienteering' as the process of active alignment of cells in response to applied force. Cytochalasin D was added in graded doses to investigate the role of the actin cytoskeleton in force perception and transmission. A clear dose response was found; at high concentrations orienteering was abolished; and the drug's impact was reversible. The two cell strains used were similar in their alignment behavior and in their responses to cytochalasin D. Orienteering was influenced by cell density, and the cell strains studied differed in this respect. Fetal cells, unlike their aged counterparts, failed to orient at high cell density. In both cell strains, mid-density cultures aligned rapidly and sparse cultures lagged. These results indicate that both cell-cell adhesion and cytoskeleton integrity are critical in mediating the orienteering response. Differences between these two cell strains may relate to their expression of extracellular matrix molecules (fibronectin, collagen type 1) integrins and their relative binding affinities.

Effect of temperature on removal of trace organic chemicals in managed aquifer recharge systems.

PubMed

Alidina, Mazahirali; Shewchuk, Justin; Drewes, Jörg E

2015-03-01

This study was undertaken to investigate whether changes in temperature experienced in MAR systems affect attenuation of trace organic chemicals (TOrCs). A set of laboratory-scale soil columns were placed in a temperature-controlled environmental chamber and operated at five different temperature set-points (30, 20, 10, 8 and 4°C) covering the range of typical groundwater temperatures in cold, moderate and arid climate regions. Removal of bulk organic carbon both in the infiltration zone as well as during deeper infiltration was independent of temperature. Of the 22 TOrCs investigated, only six chemicals exhibited changes in attenuation as a function of temperature. Attenuation of four of the compounds (diclofenac, gemfibrozil, ketoprofen and naproxen) decreased as the temperature was reduced from 30°C to 4°C, likely due to decreased microbial activity at lower temperatures. As the temperature was decreased, however, attenuation of oxybenzone and trimethoprim were noted to increase. This increased attenuation was likely due to more efficient sorption at lower temperatures, though possible changes in the microbial composition as the temperature decreased may also have contributed to this change. Changes in rate constants of attenuation (ka) for the biotransformed TOrCs with temperature suggested the existence of a critical temperature at 10°C for three of the four TOrCs, where significant changes to rates of attenuation occurred. Results from this study indicated that for most TOrCs, changes in temperature do not impact their attenuation. Thus, seasonal changes in temperature are not considered to be a major concern for attenuation of most TOrCs in MAR systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pharmacological and clinical properties of calcimimetics: calcium receptor activators that afford an innovative approach to controlling hyperparathyroidism.

PubMed

Nagano, Nobuo

2006-03-01

Circulating levels of calcium ion (Ca2+) are maintained within a narrow physiological range mainly by the action of parathyroid hormone (PTH) secreted from parathyroid gland (PTG) cells. PTG cells can sense small fluctuations in plasma Ca2+ levels by virtue of a cell surface Ca2+ receptor (CaR) that belongs to the superfamily of G protein-coupled receptors (GPCR). Compounds that activate the CaR and inhibit PTH secretion are termed 'calcimimetics' because they mimic or potentiate the effects of extracellular Ca2+ on PTG cell function. Preclinical studies with NPS R-568, a first generation calcimimetic compound that acts as a positive allosteric modulator of the CaR, have demonstrated that oral administration decreases serum levels of PTH and calcium, with a leftward shift in the set-point for calcium-regulated PTH secretion in normal rats. NPS R-568 also suppresses the elevation of serum PTH levels and PTG hyperplasia and can improve bone mineral density (BMD) and strength in rats with chronic renal insufficiency (CRI). Clinical trials with cinacalcet hydrochloride (cinacalcet), a compound with an improved metabolic profile, have shown that long-term treatment continues to suppress the elevation of serum levels of calcium and PTH in patients with primary hyperparathyroidism (1HPT). Furthermore, clinical trials in patients with uncontrolled secondary hyperparathyroidism (2HPT) have demonstrated that cinacalcet not only lowers serum PTH levels, but also the serum phosphorus and calcium x phosphorus product; these are a hallmark of an increased risk of cardiovascular disease and mortality in dialysis patients with end-stage renal disease. Indeed, cinacalcet has already been approved for marketing in several countries. Calcimimetic compounds like cinacalcet have great potential as an innovative medical approach to manage 1HPT and 2HPT.

On-Orbit Performance of the Helioseismic and Magnetic Imager Instrument onboard the Solar Dynamics Observatory

NASA Astrophysics Data System (ADS)

Hoeksema, J. T.; Baldner, C. S.; Bush, R. I.; Schou, J.; Scherrer, P. H.

2018-03-01

The Helioseismic and Magnetic Imager (HMI) instrument is a major component of NASA's Solar Dynamics Observatory (SDO) spacecraft. Since commencement of full regular science operations on 1 May 2010, HMI has operated with remarkable continuity, e.g. during the more than five years of the SDO prime mission that ended 30 September 2015, HMI collected 98.4% of all possible 45-second velocity maps; minimizing gaps in these full-disk Dopplergrams is crucial for helioseismology. HMI velocity, intensity, and magnetic-field measurements are used in numerous investigations, so understanding the quality of the data is important. This article describes the calibration measurements used to track the performance of the HMI instrument, and it details trends in important instrument parameters during the prime mission. Regular calibration sequences provide information used to improve and update the calibration of HMI data. The set-point temperature of the instrument front window and optical bench is adjusted regularly to maintain instrument focus, and changes in the temperature-control scheme have been made to improve stability in the observable quantities. The exposure time has been changed to compensate for a 20% decrease in instrument throughput. Measurements of the performance of the shutter and tuning mechanisms show that they are aging as expected and continue to perform according to specification. Parameters of the tunable optical-filter elements are regularly adjusted to account for drifts in the central wavelength. Frequent measurements of changing CCD-camera characteristics, such as gain and flat field, are used to calibrate the observations. Infrequent expected events such as eclipses, transits, and spacecraft off-points interrupt regular instrument operations and provide the opportunity to perform additional calibration. Onboard instrument anomalies are rare and seem to occur quite uniformly in time. The instrument continues to perform very well.

The pH dependency of N-converting enzymatic processes, pathways and microbes: effect on net N2 O production.

PubMed

Blum, Jan-Michael; Su, Qingxian; Ma, Yunjie; Valverde-Pérez, Borja; Domingo-Félez, Carlos; Jensen, Marlene Mark; Smets, Barth F

2018-05-01

Nitrous oxide (N 2 O) is emitted during microbiological nitrogen (N) conversion processes, when N 2 O production exceeds N 2 O consumption. The magnitude of N 2 O production vs. consumption varies with pH and controlling net N 2 O production might be feasible by choice of system pH. This article reviews how pH affects enzymes, pathways and microorganisms that are involved in N-conversions in water engineering applications. At a molecular level, pH affects activity of cofactors and structural elements of relevant enzymes by protonation or deprotonation of amino acid residues or solvent ligands, thus causing steric changes in catalytic sites or proton/electron transfer routes that alter the enzymes' overall activity. Augmenting molecular information with, e.g., nitritation or denitrification rates yields explanations of changes in net N 2 O production with pH. Ammonia oxidizing bacteria are of highest relevance for N 2 O production, while heterotrophic denitrifiers are relevant for N 2 O consumption at pH > 7.5. Net N 2 O production in N-cycling water engineering systems is predicted to display a 'bell-shaped' curve in the range of pH 6.0-9.0 with a maximum at pH 7.0-7.5. Net N 2 O production at acidic pH is dominated by N 2 O production, whereas N 2 O consumption can outweigh production at alkaline pH. Thus, pH 8.0 may be a favourable pH set-point for water treatment applications regarding net N 2 O production. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

Obese super athletes: fat-fueled migration in birds and bats.

PubMed

Guglielmo, Christopher G

2018-03-07

Migratory birds are physiologically specialized to accumulate massive fat stores (up to 50-60% of body mass), and to transport and oxidize fatty acids at very high rates to sustain flight for many hours or days. Target gene, protein and enzyme analyses and recent -omic studies of bird flight muscles confirm that high capacities for fatty acid uptake, cytosolic transport, and oxidation are consistent features that make fat-fueled migration possible. Augmented circulatory transport by lipoproteins is suggested by field data but has not been experimentally verified. Migratory bats have high aerobic capacity and fatty acid oxidation potential; however, endurance flight fueled by adipose-stored fat has not been demonstrated. Patterns of fattening and expression of muscle fatty acid transporters are inconsistent, and bats may partially fuel migratory flight with ingested nutrients. Changes in energy intake, digestive capacity, liver lipid metabolism and body temperature regulation may contribute to migratory fattening. Although control of appetite is similar in birds and mammals, neuroendocrine mechanisms regulating seasonal changes in fuel store set-points in migrants remain poorly understood. Triacylglycerol of birds and bats contains mostly 16 and 18 carbon fatty acids with variable amounts of 18:2n-6 and 18:3n-3 depending on diet. Unsaturation of fat converges near 70% during migration, and unsaturated fatty acids are preferentially mobilized and oxidized, making them good fuel. Twenty and 22 carbon n-3 and n-6 polyunsaturated fatty acids (PUFA) may affect membrane function and peroxisome proliferator-activated receptor signaling. However, evidence for dietary PUFA as doping agents in migratory birds is equivocal and requires further study. © 2018. Published by The Company of Biologists Ltd.

EEAP boiler and chiller study II at Fort Sam Houston, San Antonio, Texas. Volume II

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

The following assumptions and estimates were used in the modeling of the existing buildings which are served by the boilers and chillers included in this study. (1) The Trace 600 weather data for San Antonio, Texas was used in all of the computer simulations. (2) The Trace 600 computer simulations were performed for the months of January through December to determine annual HVAC equipment energy consumptions. (3) A special holiday schedule was created to incorporate the additional holidays that military personnel living in the area 1300 barracks buildings receive. This schedule includes the seven standard holidays plus the period frommore » December 17 through 31. The standard seven day holiday schedule was used for all other areas. (4) All building dimensions and construction data were determined from as-built drawings when available, or from field measurements taken during the site visit. (5) Design room temperatures for comfort conditions (thermostat setpoints) were obtained from CEMP-E (9 December 1991) Chapter 13, Section 3. These temperatures were 78 deg F, 50% relative humidity for cooling and 70 deg F for heating. No cooling or heating temperature setback control was included in the simulations. The design room conditions for the hospital were determined as follows: Surgery / Critical Care 68 deg F, 55%; Ancillary 72 deg F, 50%; Nursing / Patient Care 76 deg F, 50%; and Computer Room 72 deg F, 50%. (6) The shading coefficient for all windows with interior shading devices was estimated at 0.67 per ASHRAE data. (7) The number of people in each building or room was estimated from interviews with post personnel or field notes taken during the site visit. The sensible and latent heat gain rates used for the people in each room were taken from ASHRAE data.« less

Definition and means of maintaining the criticality detectors and alarms portion of the PFP safety envelope

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, W.F.

The purpose of this document is to provide the definition and means of maintaining the Safety Envelope (SE) related to the Criticality Alarm System (CAS). This document provides amplification of the Limiting Condition for Operation (LCO) described in the Plutonium Finishing Plant (PFP) Operational Safety Requirements (OSR), WHC-SD-CP-OSR-010, Rev. 0, 1994, Section 3.1.2, Criticality Detectors and Alarms. This document, with its appendices, provides the following: (1) System functional requirements for determining system operability (Section 3); (2) A list of annotated system block diagrams which indicate the safety envelope boundaries (Appendix C); (3) A list of the Safety Class 1 andmore » 2 Safety Envelope (SC-1/2 SE) equipment for input into the Master Component Index (Appendix B); (4) Functional requirements for individual SC-1/2 SE components, including appropriate setpoints and process parameters (Section 6 and Appendix A); (5) A list of the operational, maintenance and surveillance procedures necessary to operate and maintain the SC-1/2 SE components as required by the LCO (Section 6 and Appendix A).« less

In situ electrical resistivity measurements of vanadium thin films performed in vacuum during different annealing cycles

NASA Astrophysics Data System (ADS)

Pedrosa, Paulo; Cote, Jean-Marc; Martin, Nicolas; Arab Pour Yazdi, Mohammad; Billard, Alain

2017-02-01

The present study describes a sputtering and in situ vacuum electrical resistivity setup that allows a more efficient sputtering-oxidation coupling process for the fabrication of oxide compounds like vanadium dioxide, VO2. After the sputtering deposition of pure V thin films, the proposed setup enables the sample holder to be transferred from the sputtering to the in situ annealing + resistivity chamber without venting the whole system. The thermal oxidation of the V films was studied by implementing two different temperature cycles up to 550 °C, both in air (using a different resistivity setup) and vacuum conditions. Main results show that the proposed system is able to accurately follow the different temperature setpoints, presenting clean and low-noise resistivity curves. Furthermore, it is possible to identify the formation of different vanadium oxide phases in air, taking into account the distinct temperature cycles used. The metallic-like electrical properties of the annealed coatings are maintained in vacuum whereas those heated in air produce a vanadium oxide phase mixture.

In situ electrical resistivity measurements of vanadium thin films performed in vacuum during different annealing cycles.

PubMed

Pedrosa, Paulo; Cote, Jean-Marc; Martin, Nicolas; Arab Pour Yazdi, Mohammad; Billard, Alain

2017-02-01

The present study describes a sputtering and in situ vacuum electrical resistivity setup that allows a more efficient sputtering-oxidation coupling process for the fabrication of oxide compounds like vanadium dioxide, VO 2 . After the sputtering deposition of pure V thin films, the proposed setup enables the sample holder to be transferred from the sputtering to the in situ annealing + resistivity chamber without venting the whole system. The thermal oxidation of the V films was studied by implementing two different temperature cycles up to 550 °C, both in air (using a different resistivity setup) and vacuum conditions. Main results show that the proposed system is able to accurately follow the different temperature setpoints, presenting clean and low-noise resistivity curves. Furthermore, it is possible to identify the formation of different vanadium oxide phases in air, taking into account the distinct temperature cycles used. The metallic-like electrical properties of the annealed coatings are maintained in vacuum whereas those heated in air produce a vanadium oxide phase mixture.

Performance of Radiant Heating Systems of Low-Energy Buildings

NASA Astrophysics Data System (ADS)

Sarbu, Ioan; Mirza, Matei; Crasmareanu, Emanuel

2017-10-01

After the introduction of plastic piping, the application of water-based radiant heating with pipes embedded in room surfaces (i.e., floors, walls, and ceilings), has significantly increased worldwide. Additionally, interest and growth in radiant heating and cooling systems have increased in recent years because they have been demonstrated to be energy efficient in comparison to all-air distribution systems. This paper briefly describes the heat distribution systems in buildings, focusing on the radiant panels (floor, wall, ceiling, and floor-ceiling). Main objective of this study is the performance investigation of different types of low-temperature heating systems with different methods. Additionally, a comparative analysis of the energy, environmental, and economic performances of floor, wall, ceiling, and floor-ceiling heating using numerical simulation with Transient Systems Simulation (TRNSYS) software is performed. This study showed that the floor-ceiling heating system has the best performance in terms of the lowest energy consumption, operation cost, CO2 emission, and the nominal boiler power. The comparison of the room operative air temperatures and the set-point operative air temperature indicates also that all radiant panel systems provide satisfactory results without significant deviations.

Computational modeling of cardiovascular response to orthostatic stress

NASA Technical Reports Server (NTRS)

Heldt, Thomas; Shim, Eun B.; Kamm, Roger D.; Mark, Roger G.

2002-01-01

The objective of this study is to develop a model of the cardiovascular system capable of simulating the short-term (< or = 5 min) transient and steady-state hemodynamic responses to head-up tilt and lower body negative pressure. The model consists of a closed-loop lumped-parameter representation of the circulation connected to set-point models of the arterial and cardiopulmonary baroreflexes. Model parameters are largely based on literature values. Model verification was performed by comparing the simulation output under baseline conditions and at different levels of orthostatic stress to sets of population-averaged hemodynamic data reported in the literature. On the basis of experimental evidence, we adjusted some model parameters to simulate experimental data. Orthostatic stress simulations are not statistically different from experimental data (two-sided test of significance with Bonferroni adjustment for multiple comparisons). Transient response characteristics of heart rate to tilt also compare well with reported data. A case study is presented on how the model is intended to be used in the future to investigate the effects of post-spaceflight orthostatic intolerance.

Mechanism and design of intermittent aeration activated sludge process for nitrogen removal.

PubMed

Hanhan, Oytun; Insel, Güçlü; Yagci, Nevin Ozgur; Artan, Nazik; Orhon, Derin

2011-01-01

The paper provided a comprehensive evaluation of the mechanism and design of intermittent aeration activated sludge process for nitrogen removal. Based on the specific character of the process the total cycle time, (T(C)), the aerated fraction, (AF), and the cycle time ratio, (CTR) were defined as major design parameters, aside from the sludge age of the system. Their impact on system performance was evaluated by means of process simulation. A rational design procedure was developed on the basis of basic stochiometry and mass balance related to the oxidation and removal of nitrogen under aerobic and anoxic conditions, which enabled selected of operation parameters of optimum performance. The simulation results indicated that the total nitrogen level could be reduced to a minimum level by appropriate manipulation of the aerated fraction and cycle time ratio. They also showed that the effluent total nitrogen could be lowered to around 4.0 mgN/L by adjusting the dissolved oxygen set-point to 0.5 mg/L, a level which promotes simultaneous nitrification and denitrification.

Time- and polarity-dependent proteomic changes associated with homeostatic scaling at central synapses

PubMed Central

Schanzenbächer, Christoph T

2018-01-01

In homeostatic scaling at central synapses, the depth and breadth of cellular mechanisms that detect the offset from the set-point, detect the duration of the offset and implement a cellular response are not well understood. To understand the time-dependent scaling dynamics we treated cultured rat hippocampal cells with either TTX or bicucculline for 2 hr to induce the process of up- or down-scaling, respectively. During the activity manipulation we metabolically labeled newly synthesized proteins using BONCAT. We identified 168 newly synthesized proteins that exhibited significant changes in expression. To obtain a temporal trajectory of the response, we compared the proteins synthesized within 2 hr or 24 hr of the activity manipulation. Surprisingly, there was little overlap in the significantly regulated newly synthesized proteins identified in the early- and integrated late response datasets. There was, however, overlap in the functional categories that are modulated early and late. These data indicate that within protein function groups, different proteomic choices can be made to effect early and late homeostatic responses that detect the duration and polarity of the activity manipulation. PMID:29447110

Experimental reconstitution of chronic ER stress in the liver reveals feedback suppression of BiP mRNA expression

PubMed Central

Gomez, Javier A; Rutkowski, D Thomas

2016-01-01

Endoplasmic reticulum (ER) stress is implicated in many chronic diseases, but very little is known about how the unfolded protein response (UPR) responds to persistent ER stress in vivo. Here, we experimentally reconstituted chronic ER stress in the mouse liver, using repeated injection of a low dose of the ER stressor tunicamycin. Paradoxically, this treatment led to feedback-mediated suppression of a select group of mRNAs, including those encoding the ER chaperones BiP and GRP94. This suppression was due to both silencing of the ATF6α pathway of UPR-dependent transcription and enhancement of mRNA degradation, possibly via regulated IRE1-dependent decay (RIDD). The suppression of mRNA encoding BiP was phenocopied by ectopic overexpression of BiP protein, and was also observed in obese mice. Our findings suggest that persistent cycles of UPR activation and deactivation create an altered, quasi-stable setpoint for UPR-dependent transcriptional regulation—an outcome that could be relevant to conditions such as metabolic syndrome. DOI: http://dx.doi.org/10.7554/eLife.20390.001 PMID:27938665

Energy Efficient Operation of Ammonia Refrigeration Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammed, Abdul Qayyum; Wenning, Thomas J; Sever, Franc

Ammonia refrigeration systems typically offer many energy efficiency opportunities because of their size and complexity. This paper develops a model for simulating single-stage ammonia refrigeration systems, describes common energy saving opportunities, and uses the model to quantify those opportunities. The simulation model uses data that are typically available during site visits to ammonia refrigeration plants and can be calibrated to actual consumption and performance data if available. Annual electricity consumption for a base-case ammonia refrigeration system is simulated. The model is then used to quantify energy savings for six specific energy efficiency opportunities; reduce refrigeration load, increase suction pressure, employmore » dual suction, decrease minimum head pressure set-point, increase evaporative condenser capacity, and reclaim heat. Methods and considerations for achieving each saving opportunity are discussed. The model captures synergistic effects that result when more than one component or parameter is changed. This methodology represents an effective method to model and quantify common energy saving opportunities in ammonia refrigeration systems. The results indicate the range of savings that might be expected from common energy efficiency opportunities.« less

Pretest analysis document for Test S-NH-2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Streit, J.E.; Owca, W.A.

This report documents the pretest analysis calculation completed with the RELAP5/MOD2/CY3601 code for Semiscale MOD-2C Test S-NH-2. The test will simulate the transient that results from the shear in a small diameter penetration of a cold leg, equivalent to 2.1% of the cold leg flow area. The high pressure injection system is assumed to be inoperative throughout the transient. The recovery procedure consists of latching open both steam generator atmospheric dump valves, supplying both steam generators with auxiliary feedwater system is assumed to be partially inoperative so the auxiliary feedwater flow is degraded. Recovery will be initiated upon a peakmore » cladding temperature of 811/sup 0/K (1000/sup 0/F). The test will be terminated when primary pressure has been reduced to the low pressure injection system setpoint of 1.38 MPa (200 psia). The calculated results indicate that the test objectives can be achieved and the proposed test scenario poses no threat to personnel or to plant integrity. 7 refs., 16 figs., 2 tabs.« less

Strategies for enhanced deammonification performance and reduced nitrous oxide emissions.

PubMed

Leix, Carmen; Drewes, Jörg E; Ye, Liu; Koch, Konrad

2017-07-01

Deammonification's performance and associated nitrous oxide emissions (N 2 O) depend on operational conditions. While studies have investigated factors for high performances and low emissions separately, this study investigated optimizing deammonification performance while simultaneously reducing N 2 O emissions. Using a design of experiment (DoE) method, two models were developed for the prediction of the nitrogen removal rate and N 2 O emissions during single-stage deammonification considering three operational factors (i.e., pH value, feeding and aeration strategy). The emission factor varied between 0.7±0.5% and 4.1±1.2% at different DoE-conditions. The nitrogen removal rate was predicted to be maximized at settings of pH 7.46, intermittent feeding and aeration. Conversely, emissions were predicted to be minimized at the design edges at pH 7.80, single feeding, and continuous aeration. Results suggested a weak positive correlation between the nitrogen removal rate and N 2 O emissions, thus, a single optimizing operational set-point for maximized performance and minimized emissions did not exist. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analgesia and hyperalgesia from GABA-mediated modulation of the cerebral cortex.

PubMed

Jasmin, Luc; Rabkin, Samuel D; Granato, Alberto; Boudah, Abdennacer; Ohara, Peter T

2003-07-17

It is known that pain perception can be altered by mood, attention and cognition, or by direct stimulation of the cerebral cortex, but we know little of the neural mechanisms underlying the cortical modulation of pain. One of the few cortical areas consistently activated by painful stimuli is the rostral agranular insular cortex (RAIC) where, as in other parts of the cortex, the neurotransmitter gamma-aminobutyric acid (GABA) robustly inhibits neuronal activity. Here we show that changes in GABA neurotransmission in the RAIC can raise or lower the pain threshold--producing analgesia or hyperalgesia, respectively--in freely moving rats. Locally increasing GABA, by using an enzyme inhibitor or gene transfer mediated by a viral vector, produces lasting analgesia by enhancing the descending inhibition of spinal nociceptive neurons. Selectively activating GABA(B)-receptor-bearing RAIC neurons produces hyperalgesia through projections to the amygdala, an area involved in pain and fear. Whereas most studies focus on the role of the cerebral cortex as the end point of nociceptive processing, we suggest that cerebral cortex activity can change the set-point of pain threshold in a top-down manner.

Quadratic Programming for Allocating Control Effort

NASA Technical Reports Server (NTRS)

Singh, Gurkirpal

2005-01-01

A computer program calculates an optimal allocation of control effort in a system that includes redundant control actuators. The program implements an iterative (but otherwise single-stage) algorithm of the quadratic-programming type. In general, in the quadratic-programming problem, one seeks the values of a set of variables that minimize a quadratic cost function, subject to a set of linear equality and inequality constraints. In this program, the cost function combines control effort (typically quantified in terms of energy or fuel consumed) and control residuals (differences between commanded and sensed values of variables to be controlled). In comparison with prior control-allocation software, this program offers approximately equal accuracy but much greater computational efficiency. In addition, this program offers flexibility, robustness to actuation failures, and a capability for selective enforcement of control requirements. The computational efficiency of this program makes it suitable for such complex, real-time applications as controlling redundant aircraft actuators or redundant spacecraft thrusters. The program is written in the C language for execution in a UNIX operating system.

Dispatching power system for preventive and corrective voltage collapse problem in a deregulated power system

NASA Astrophysics Data System (ADS)

Alemadi, Nasser Ahmed

Deregulation has brought opportunities for increasing efficiency of production and delivery and reduced costs to customers. Deregulation has also bought great challenges to provide the reliability and security customers have come to expect and demand from the electrical delivery system. One of the challenges in the deregulated power system is voltage instability. Voltage instability has become the principal constraint on power system operation for many utilities. Voltage instability is a unique problem because it can produce an uncontrollable, cascading instability that results in blackout for a large region or an entire country. In this work we define a system of advanced analytical methods and tools for secure and efficient operation of the power system in the deregulated environment. The work consists of two modules; (a) contingency selection module and (b) a Security Constrained Optimization module. The contingency selection module to be used for voltage instability is the Voltage Stability Security Assessment and Diagnosis (VSSAD). VSSAD shows that each voltage control area and its reactive reserve basin describe a subsystem or agent that has a unique voltage instability problem. VSSAD identifies each such agent. VS SAD is to assess proximity to voltage instability for each agent and rank voltage instability agents for each contingency simulated. Contingency selection and ranking for each agent is also performed. Diagnosis of where, why, when, and what can be done to cure voltage instability for each equipment outage and transaction change combination that has no load flow solution is also performed. A security constrained optimization module developed solves a minimum control solvability problem. A minimum control solvability problem obtains the reactive reserves through action of voltage control devices that VSSAD determines are needed in each agent to obtain solution of the load flow. VSSAD makes a physically impossible recommendation of adding reactive generation capability to specific generators to allow a load flow solution to be obtained. The minimum control solvability problem can also obtain solution of the load flow without curtailing transactions that shed load and generation as recommended by VSSAD. A minimum control solvability problem will be implemented as a corrective control, that will achieve the above objectives by using minimum control changes. The control includes; (1) voltage setpoint on generator bus voltage terminals; (2) under load tap changer tap positions and switchable shunt capacitors; and (3) active generation at generator buses. The minimum control solvability problem uses the VSSAD recommendation to obtain the feasible stable starting point but completely eliminates the impossible or onerous recommendation made by VSSAD. This thesis reviews the capabilities of Voltage Stability Security Assessment and Diagnosis and how it can be used to implement a contingency selection module for the Open Access System Dispatch (OASYDIS). The OASYDIS will also use the corrective control computed by Security Constrained Dispatch. The corrective control would be computed off line and stored for each contingency that produces voltage instability. The control is triggered and implemented to correct the voltage instability in the agent experiencing voltage instability only after the equipment outage or operating changes predicted to produce voltage instability have occurred. The advantages and the requirements to implement the corrective control are also discussed.

Breathing regulation and blood gas homeostasis after near complete lesions of the retrotrapezoid nucleus in adult rats.

PubMed

Souza, George M P R; Kanbar, Roy; Stornetta, Daniel S; Abbott, Stephen B G; Stornetta, Ruth L; Guyenet, Patrice G

2018-04-18

The retrotrapezoid nucleus (RTN) is one of several CNS nuclei that contribute, in various capacities (e.g. CO 2 detection, neuronal modulation) to the central respiratory chemoreflex (CRC). Here we test how important the RTN is to PCO 2 homeostasis and breathing during sleep or wake. RTN Nmb positive neurons were killed with targeted microinjections of substance-P-saporin conjugate in adult rats. Under normoxia, rats with large RTN lesions (92 ± 4 % cell loss) had normal blood pressure (BP) and arterial pH but were hypoxic (-8 mmHg PaO 2 ) and hypercapnic (+10 mmHg PaCO 2 ). In resting conditions, minute-volume (V E ) was normal but breathing frequency (f R ) was elevated and tidal volume (V T ) reduced. Resting O 2 consumption and CO 2 production were normal. The hypercapnic ventilatory reflex in 65% FiO 2 had an inverse exponential relationship with the number of surviving RTN neurons and was decreased by up to 92%. The hypoxic ventilatory reflex (HVR; FiO 2 21-10%) persisted after RTN lesions, hypoxia-induced sighing was normal and hypoxia-induced hypotension reduced. In rats with RTN lesions, breathing was lowest during slow-wave sleep (SWS), especially under hyperoxia, but apneas and sleep-disordered breathing were not observed. In conclusion, near complete RTN destruction in rats virtually eliminates the CRC but HVR persists and sighing and the state-dependence of breathing are unchanged. Under normoxia, RTN lesions cause no change in V E but alveolar ventilation is reduced by at least 21%, probably because of increased physiological dead volume. RTN lesions do not cause sleep apnea during SWS, even under hyperoxia. Background: the retrotrapezoid nucleus (RTN) drives breathing proportionally to brain PCO 2 but its role during various states of vigilance needed clarification. New result: Under normoxia, RTN lesions increase the arterial PCO 2 set-point, lower the PO 2 set-point and reduce alveolar ventilation relative to CO 2 production. Tidal volume is reduced and breathing frequency increased to a comparable degree during wake, slow-wave sleep and REM sleep. RTN lesions do not produce apneas or disordered breathing during sleep. New result: RTN lesions in rats virtually eliminate the central respiratory chemoreflex (CRC) while preserving the cardiorespiratory responses to hypoxia; the relationship between CRC and number of surviving RTN Nmb neurons is an inverse exponential. the CRC does not function without the RTN. In the quasi-complete absence of the RTN and CRC, alveolar ventilation is reduced despite an increased drive to breathe from the carotid bodies. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Program control for mission success

NASA Technical Reports Server (NTRS)

Longanecker, G. W.

1994-01-01

This article suggests that in order to be able to exercise control over a particular program, the program itself must be controllable. A controllable program therefore, according to the author, is one that has been properly scoped technically, realistically scheduled, and adequately budgeted. The article delves indepth into each of the above aspects of a controllable program and discusses both the pros and cons of each.

Endocan, TGF-beta, and ADMA as Risk Factors for Endothelial Dysfunction and Possible Vascular Disease in Patients with Subclinical Hypothyroidism.

PubMed

Arpaci, Dilek; Karakece, Engin; Tocoglu, Aysel Gurkan; Ergenc, Hasan; Gurol, Gonul; Ciftci, Ihsan Hakki; Tamer, Ali

2016-12-01

Although the relationship between atherosclerosis and overt hypothyroidism has been confirmed, it remains controversial in cases of subclinical hypothyroidism. Higher TSH and similar T4 suggest differences in set-points or differences due to diagnostic limitations regarding subclinical hypothyroidism. Endothelial dysfunction (ED) is a marker rather than a precursor of cardiovascular disease. Asymmetric dimethylarginine (ADMA) and endocan are known as novel markers of ED in various diseases. Transforming growth factor-beta (TGF-β) has a protective role against autoimmune diseases such as thyroiditis. This study aimed to determine the relationships between serum ADMA, endocan, TGF-β, and the high-sensitivity C-reactive protein (hs-CRP) levels, a proven indicator of ED, in patients with SH. Thirty-five patients with SH and 21 age- and sex-matched euthyroid subjects were included in the study. The levels of TSH, FT4, lipid parameters, endocan, ADMA, TGF-β, and hs-CRP were measured. No significant differences in age or sex were found between the patient and control groups (p=0.294 and 0.881, respectively). Mean TSH level was higher in the patient group (p=0.005), whereas mean fT4 level was similar in two groups (p=0.455). The average hs-CRP, endocan, TGF-β l level in the patient group was higher than control group (p=0.001; P=0.012; P=0.025; P<0.01 respectively). A positive correlation was found between the endocan and ADMA levels (r=0.760, p=0.000). ADMA levels also were positively correlated with hs-CRP. Both the TSH and low-density lipoprotein cholesterol (LDL-C) levels were positively correlated with the hs-CRP level. Subclinical hypothyroidism is associated with increased levels of serum endocan, ADMA, and TGF-β, which are new markers for ED. In particular, ADMA was correlated with both endocan and hs-CRP levels. These findings are suggestive for increased risk of ED and subsequent development of atherosclerosis in patients with SH. © 2016 by the Association of Clinical Scientists, Inc.

Intranasal Administration of a Therapeutic HIV Vaccine (Vacc-4x) Induces Dose-Dependent Systemic and Mucosal Immune Responses in a Randomized Controlled Trial

PubMed Central

Brekke, Kristin; Lind, Andreas; Holm-Hansen, Carol; Haugen, Inger Lise; Sørensen, Birger; Sommerfelt, Maja; Kvale, Dag

2014-01-01

Background Vacc-4x, a Gag p24-based therapeutic HIV vaccine, has been shown to reduce viral load set-points after intradermal administration. In this randomized controlled pilot study we investigate intranasal administration of Vacc-4x with Endocine as adjuvant. Methods Safety and immunogenicity were tested in patients on effective ART. They were randomized to low, medium or high dose Vacc-4x or adjuvant alone, administered four times at weekly intervals with no booster. Vacc-4x-specific T cell responses were measured in vitro by proliferation and in vivo by a single DTH skin test at the end of study. Nasal and rectal mucosal secretions were analyzed for Vacc-4x-specific antibodies by ELISA. Immune regulation induced by Vacc-4x was assessed by functional blockade of the regulatory cytokines IL-10 and TGF-β. Results Vacc-4x proliferative T cell responses increased only among the vaccinated (p≤0.031). The low dose group showed the greatest increase in Vacc-4x CD8+T cell responses (p = 0.037) and developed larger DTH (p = 0.005) than the adjuvant group. Rectal (distal) Vacc-4x IgA and IgG antibodies also increased (p = 0.043) in this group. In contrast, the high dose generated higher nasal (local) Vacc-4x IgA (p = 0.028) and serum IgG (p = 0.030) antibodies than the adjuvant. Irrespective of dose, increased Vacc-4x CD4+T cell responses were associated with low proliferation (r = −0.82, p<0.001) and high regulation (r = 0.61, p = 0.010) at baseline. Conclusion Intranasal administration of Vacc-4x with Endocine was safe and induced dose-dependent vaccine-specific T cell responses and both mucosal and systemic humoral responses. The clinical significance of dose, immune regulation and mucosal immunity warrants further investigation. Trial Registration ClinicalTrials.gov NCT01473810 PMID:25398137

Vector control activities: Fiscal Year, 1986

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1987-04-01

The program is divided into two major components - operations and support studies. The support studies are designed to improve the operational effectiveness and efficiency of the control program and to identify other vector control problems requiring TVA attention and study. Nonchemical methods of control are emphasized and are supplemented with chemical measures as needed. TVA also cooperates with various concerned municipalities in identifying blood-sucking arthropod pest problems and demonstrating control techniques useful in establishing abatement programs, and provides technical assistance to other TVA programs and organizations. The program also helps Land Between The Lakes (LBL) plan and conduct vectormore » control operations and tick control research. Specific program control activities and support studies are discussed.« less

48 CFR 519.7014 - Internal controls.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 48 Federal Acquisition Regulations System 4 2012-10-01 2012-10-01 false Internal controls. 519... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS GSA Mentor-Protégé Program 519.7014 Internal controls. (a) The GSA Mentor-Protégé Program Manager will manage the Program. Internal controls will be established by...

48 CFR 519.7014 - Internal controls.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Internal controls. 519... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS GSA Mentor-Protégé Program 519.7014 Internal controls. (a) The GSA Mentor-Protégé Program Manager will manage the Program. Internal controls will be established by...

48 CFR 519.7014 - Internal controls.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false Internal controls. 519... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS GSA Mentor-Protégé Program 519.7014 Internal controls. (a) The GSA Mentor-Protégé Program Manager will manage the Program. Internal controls will be established by...

48 CFR 519.7014 - Internal controls.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 48 Federal Acquisition Regulations System 4 2013-10-01 2013-10-01 false Internal controls. 519... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS GSA Mentor-Protégé Program 519.7014 Internal controls. (a) The GSA Mentor-Protégé Program Manager will manage the Program. Internal controls will be established by...

48 CFR 519.7014 - Internal controls.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false Internal controls. 519... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS GSA Mentor-Protégé Program 519.7014 Internal controls. (a) The GSA Mentor-Protégé Program Manager will manage the Program. Internal controls will be established by...

Hopewell Beneficial CO2 Capture for Production of Fuels, Fertilizer and Energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

UOP; Honeywell Resins & Chemicals; Honeywell Process Solutions

2010-09-30

For Phase 1 of this project, the Hopewell team developed a detailed design for the Small Scale Pilot-Scale Algal CO2 Sequestration System. This pilot consisted of six (6) x 135 gallon cultivation tanks including systems for CO2 delivery and control, algal cultivation, and algal harvesting. A feed tank supplied Hopewell wastewater to the tanks and a receiver tank collected the effluent from the algal cultivation system. The effect of environmental parameters and nutrient loading on CO2 uptake and sequestration into biomass were determined. Additionally the cost of capturing CO2 from an industrial stack emission at both pilot and full-scale wasmore » determined. The engineering estimate evaluated Amine Guard technology for capture of pure CO2 and direct stack gas capture and compression. The study concluded that Amine Guard technology has lower lifecycle cost at commercial scale, although the cost of direct stack gas capture is lower at the pilot scale. Experiments conducted under high concentrations of dissolved CO2 did not demonstrate enhanced algae growth rate. This result suggests that the dissolved CO2 concentration at neutral pH was already above the limiting value. Even though dissolved CO2 did not show a positive effect on biomass growth, controlling its value at a constant set-point during daylight hours can be beneficial in an algae cultivation stage with high algae biomass concentration to maximize the rate of CO2 uptake. The limited enhancement of algal growth by CO2 addition to Hopewell wastewater was due at least in part to the high endogenous CO2 evolution from bacterial degradation of dissolved organic carbon present at high levels in the wastewater. It was found that the high level of bacterial activity was somewhat inhibitory to algal growth in the Hopewell wastewater. The project demonstrated that the Honeywell automation and control system, in combination with the accuracy of the online pH, dissolved O2, dissolved CO2, turbidity, Chlorophyll A and conductivity sensors is suitable for process control of algae cultivation in an open pond systems. This project concluded that the Hopewell wastewater is very suitable for algal cultivation but the potential for significant CO2 sequestration from the plant stack gas emissions was minimal due to the high endogenous CO2 generation in the wastewater from the organic wastewater content. Algae cultivation was found to be promising, however, for nitrogen remediation in the Hopewell wastewater.« less

Propulsion control experience used in the Highly Integrated Digital Electronic Control (HIDEC) program

NASA Technical Reports Server (NTRS)

Myers, L. P.; Burcham, F. W., Jr.

1984-01-01

The highly integrated digital electronic control (HIDEC) program will integrate the propulsion and flight control systems on an F-15 airplane at NASA Ames Research Center's Dryden Flight Research Facility. Ames-Dryden has conducted several propulsion control programs that have contributed to the HIDEC program. The digital electronic engine control (DEEC) flight evaluation investigated the performance and operability of the F100 engine equipped with a full-authority digital electronic control system. Investigations of nozzle instability, fault detection and accommodation, and augmentor transient capability provided important information for the HIDEC program. The F100 engine model derivative (EMD) was also flown in the F-15 airplane, and airplane performance was significantly improved. A throttle response problem was found and solved with a software fix to the control logic. For the HIDEC program, the F100 EMD engines equipped with DEEC controls will be integrated with the digital flight control system. The control modes to be implemented are an integrated flightpath management mode and an integrated adaptive engine control system mode. The engine control experience that will be used in the HIDEC program is discussed.

Generic command interpreter for robot controllers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Werner, J.

1991-04-09

Generic command interpreter programs have been written for robot controllers at Sandia National Laboratories (SNL). Each interpreter program resides on a robot controller and interfaces the controller with a supervisory program on another (host) computer. We call these interpreter programs monitors because they wait, monitoring a communication line, for commands from the supervisory program. These monitors are designed to interface with the object-oriented software structure of the supervisory programs. The functions of the monitor programs are written in each robot controller's native language but reflect the object-oriented functions of the supervisory programs. These functions and other specifics of the monitormore » programs written for three different robots at SNL will be discussed. 4 refs., 4 figs.« less

Assessing the present state and potential of Medicaid controlled substance lock-in programs.

PubMed

Roberts, Andrew W; Skinner, Asheley Cockrell

2014-05-01

Nonmedical use of prescription medications--particularly controlled substances--has risen dramatically in recent decades, resulting in alarming increases in overdose-related health care utilization, costs, and mortality. The Centers for Disease Control and Prevention estimate that 80% of abused and misused controlled substances originate as legal prescriptions. As such, policymakers and payers have the opportunity to combat nonmedical use by regulating controlled substance accessibility within legal prescribing and dispensing processes. One common policy strategy is found in Medicaid controlled substance lock-in programs. Lock-in programs identify Medicaid beneficiaries exhibiting high-risk controlled substance seeking behavior and "lock in" these patients to, typically, a single prescriber and pharmacy from which they may obtain Medicaid-covered controlled substance prescriptions. Lock-in restrictions are intended to improve care coordination between providers, reduce nonmedical use behaviors, and limit Medicaid costs stemming from nonmedical use and diversion. Peer-reviewed and gray literature have been examined to assess the current prevalence and design of Medicaid lock-in programs, as well as the current evidence base for informing appropriate program design and understanding program effectiveness. Forty-six state Medicaid agencies currently operate lock-in programs. Program design varies widely between states in terms of defining high-risk controlled substance use, the scope of actual lock-in restrictions, and length of program enrollment. Additionally, there is a remarkable dearth of peer-reviewed literature evaluating the design and effectiveness of Medicaid lock-in programs. Nearly all outcomes evidence stemmed from publicly accessible internal Medicaid program evaluations, which largely investigated cost savings to the state. Lock-in programs are highly prevalent and poised to play a meaningful role in curbing the prescription drug abuse epidemic. However, achieving these ends requires a concerted effort from the academic and policy communities to rigorously evaluate the effect of lock-in programs on patient outcomes, determine optimal program design, and explore opportunities to enhance lock-in program impact through coordination with parallel controlled substance policy efforts, namely prescription drug-monitoring programs.

7 CFR 58.147 - Insect and rodent control program.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false Insect and rodent control program. 58.147 Section 58... Service 1 Operations and Operating Procedures § 58.147 Insect and rodent control program. In addition to... made responsible for the performance of a regularly scheduled insect and rodent control program...

48 CFR 819.7112 - Internal controls.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Internal controls. 819... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS VA Mentor-Protégé Program 819.7112 Internal controls. (a) OSDBU... Program objectives. OSDBU will establish internal controls as checks and balances applicable to the...

48 CFR 819.7112 - Internal controls.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Internal controls. 819... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS VA Mentor-Protégé Program 819.7112 Internal controls. (a) OSDBU... Program objectives. OSDBU will establish internal controls as checks and balances applicable to the...

48 CFR 819.7112 - Internal controls.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Internal controls. 819... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS VA Mentor-Protégé Program 819.7112 Internal controls. (a) OSDBU... Program objectives. OSDBU will establish internal controls as checks and balances applicable to the...

48 CFR 819.7112 - Internal controls.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Internal controls. 819... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS VA Mentor-Protégé Program 819.7112 Internal controls. (a) OSDBU... Program objectives. OSDBU will establish internal controls as checks and balances applicable to the...

7 CFR 58.147 - Insect and rodent control program.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 3 2011-01-01 2011-01-01 false Insect and rodent control program. 58.147 Section 58... Service 1 Operations and Operating Procedures § 58.147 Insect and rodent control program. In addition to... made responsible for the performance of a regularly scheduled insect and rodent control program...