Method and apparatus for controlling fluid flow

DOEpatents

Miller, J.R.

1980-06-27

A method and apparatus for precisely controlling the rate (and hence amount) of fluid flow are given. The controlled flow rate is finely adjustable, can be extremely small (on the order of microliter-atmospheres per second), can be adjusted to zero (flow stopped), and is stable to better than 1% with time. The dead volume of the valve can be made arbitrarily small, in fact essentially zero. The valve employs no wearing mechanical parts (including springs, stems, or seals). The valve is finely adjustable, has a flow rate dynamic range of many decades, can be made compatible with any fluid, and is suitable for incorporation into an open or closed loop servo-control system.

Interactive grid generation for turbomachinery flow field simulations

NASA Technical Reports Server (NTRS)

Choo, Yung K.; Eiseman, Peter R.; Reno, Charles

1988-01-01

The control point form of algebraic grid generation presented provides the means that are needed to generate well structured grids for turbomachinery flow simulations. It uses a sparse collection of control points distributed over the flow domain. The shape and position of coordinate curves can be adjusted from these control points while the grid conforms precisely to all boundaries. An interactive program called TURBO, which uses the control point form, is being developed. Basic features of the code are discussed and sample grids are presented. A finite volume LU implicit scheme is used to simulate flow in a turbine cascade on the grid generated by the program.

Interactive grid generation for turbomachinery flow field simulations

NASA Technical Reports Server (NTRS)

Choo, Yung K.; Reno, Charles; Eiseman, Peter R.

1988-01-01

The control point form of algebraic grid generation presented provides the means that are needed to generate well structured grids of turbomachinery flow simulations. It uses a sparse collection of control points distributed over the flow domain. The shape and position of coordinate curves can be adjusted from these control points while the grid conforms precisely to all boundaries. An interactive program called TURBO, which uses the control point form, is being developed. Basic features of the code are discussed and sample grids are presented. A finite volume LU implicit scheme is used to simulate flow in a turbine cascade on the grid generated by the program.

Biofilm development of an opportunistic model bacterium analysed at high spatiotemporal resolution in the framework of a precise flow cell

PubMed Central

Lim, Chun Ping; Mai, Phuong Nguyen Quoc; Roizman Sade, Dan; Lam, Yee Cheong; Cohen, Yehuda

2016-01-01

Life of bacteria is governed by the physical dimensions of life in microscales, which is dominated by fast diffusion and flow at low Reynolds numbers. Microbial biofilms are structurally and functionally heterogeneous and their development is suggested to be interactively related to their microenvironments. In this study, we were guided by the challenging requirements of precise tools and engineered procedures to achieve reproducible experiments at high spatial and temporal resolutions. Here, we developed a robust precise engineering approach allowing for the quantification of real-time, high-content imaging of biofilm behaviour under well-controlled flow conditions. Through the merging of engineering and microbial ecology, we present a rigorous methodology to quantify biofilm development at resolutions of single micrometre and single minute, using a newly developed flow cell. We designed and fabricated a high-precision flow cell to create defined and reproducible flow conditions. We applied high-content confocal laser scanning microscopy and developed image quantification using a model biofilm of a defined opportunistic strain, Pseudomonas putida OUS82. We observed complex patterns in the early events of biofilm formation, which were followed by total dispersal. These patterns were closely related to the flow conditions. These biofilm behavioural phenomena were found to be highly reproducible, despite the heterogeneous nature of biofilm. PMID:28721252

A High Precision $3.50 Open Source 3D Printed Rain Gauge Calibrator

NASA Astrophysics Data System (ADS)

Lopez Alcala, J. M.; Udell, C.; Selker, J. S.

2017-12-01

Currently available rain gauge calibrators tend to be designed for specific rain gauges, are expensive, employ low-precision water reservoirs, and do not offer the flexibility needed to test the ever more popular small-aperture rain gauges. The objective of this project was to develop and validate a freely downloadable, open-source, 3D printed rain gauge calibrator that can be adjusted for a wide range of gauges. The proposed calibrator provides for applying low, medium, and high intensity flow, and allows the user to modify the design to conform to unique system specifications based on parametric design, which may be modified and printed using CAD software. To overcome the fact that different 3D printers yield different print qualities, we devised a simple post-printing step that controlled critical dimensions to assure robust performance. Specifically, the three orifices of the calibrator are drilled to reach the three target flow rates. Laboratory tests showed that flow rates were consistent between prints, and between trials of each part, while the total applied water was precisely controlled by the use of a volumetric flask as the reservoir.

Precision control of eluted activity from a Sr/Rb generator for cardiac positron emission tomography.

PubMed

Klein, R; Adler, A; Beanlands, R S; deKemp, R A

2004-01-01

A rubidium-82 (/sup 82/Rb) elution system is described for use with clinical positron emission tomography. The system is self-calibrating with 1.4% repeatability, independent of generator activity and elution flow rate. Saline flow is switched between a /sup 82/Sr//sup 82/Rb generator and a bypass line to achieve a constant activity elution of /sup 82/Rb. In the present study, pulse width modulation (PWM) of a solenoid valve is compared to simple threshold control as a means to simulate a proportional valve. A predictive-corrective control algorithm is developed which produces a constant activity elution within the constraints of long feedback delay and short elution time. Accurate constant-activity elutions of 10-70% of the total generator activity were demonstrated using the threshold comparison control. The adaptive-corrective control of the PWM valve provided a substantial improvement in precision of the steady-state output.

Precise nanoliter fluid handling system with integrated high-speed flow sensor.

PubMed

Haber, Carsten; Boillat, Marc; van der Schoot, Bart

2005-04-01

A system for accurate low-volume delivery of liquids in the micro- to nanoliter range makes use of an integrated miniature flow sensor as part of an intelligent feedback control loop driving a micro-solenoid valve. The flow sensor is hydraulically connected with the pressurized system liquid in the dispensing channel and located downstream from the pressure source, above the solenoid valve. The sensor operates in a differential mode and responds in real-time to the internal flow-pulse resulting from the brief opening interval of the solenoid valve leading to a rapid ejection of a fluid droplet. The integral of the flow-pulse delivered by the sensor is directly proportional to the volume of the ejected droplet from the nozzle. The quantitative information is utilized to provide active control of the effectively dispensed or aspirated volume by adjusting the solenoid valve accordingly. This process significantly enhances the precision of the fluid delivery. The system furthermore compensates automatically for any changes in the viscosity of the dispensed liquid. The data delivered by the flow sensor can be saved and backtracked in order to confirm and validate the aspiration and dispensing process in its entirety. The collected dispense information can be used for quality control assessments and automatically be made part of an electronic record.

High precision high flow range control valve

DOEpatents

McCray, J.A.

1999-07-13

A fluid control valve is described having a valve housing having first and second valve housing openings for the ingress and egress of fluid through the control valve. Disposed within a void formed by the control valve is a sleeve having at least one sleeve opening to permit the flow of fluid therethrough. A flow restricter travels within the sleeve to progressively block off the sleeve opening and thereby control flow. A fluid passageway is formed between the first valve housing opening and the outer surface of the sleeve. A second fluid passageway is formed between the inside of the sleeve and the second valve housing opening. Neither fluid passageway contains more than one 90 [degree] turn. In the preferred embodiment only one of the two fluid passageways contains a 90[degree] turn. In another embodiment, the control valve housing is bifurcated by a control surface having control surface opening disposed therethrough. A flow restricter is in slidable contact with the control surface to restrict flow of fluid through the control surface openings. 12 figs.

High precision high flow range control valve

DOEpatents

McCray, John A.

1999-01-01

A fluid control valve is described having a valve housing having first and second valve housing openings for the ingress and egress of fluid through the control valve. Disposed within a void formed by the control valve is a sleeve having at least one sleeve opening to permit the flow of fluid therethrough. A flow restricter travels within the sleeve to progressively block off the sleeve opening and thereby control flow. A fluid passageway is formed between the first valve housing opening and the outer surface of the sleeve. A second fluid passageway is formed between the inside of the sleeve and the second valve housing opening. Neither fluid passageway contains more than one 90.degree. turn. In the preferred embodiment only one of the two fluid passageways contains a 90.degree. turn. In another embodiment, the control valve housing is bifurcated by a control surface having control surface opening disposed therethrough. A flow restricter is in slidable contact with the control surface to restrict flow of fluid through the control surface openings.

Tuning-free controller to accurately regulate flow rates in a microfluidic network

NASA Astrophysics Data System (ADS)

Heo, Young Jin; Kang, Junsu; Kim, Min Jun; Chung, Wan Kyun

2016-03-01

We describe a control algorithm that can improve accuracy and stability of flow regulation in a microfluidic network that uses a conventional pressure pump system. The algorithm enables simultaneous and independent control of fluid flows in multiple micro-channels of a microfluidic network, but does not require any model parameters or tuning process. We investigate robustness and optimality of the proposed control algorithm and those are verified by simulations and experiments. In addition, the control algorithm is compared with a conventional PID controller to show that the proposed control algorithm resolves critical problems induced by the PID control. The capability of the control algorithm can be used not only in high-precision flow regulation in the presence of disturbance, but in some useful functions for lab-on-a-chip devices such as regulation of volumetric flow rate, interface position control of two laminar flows, valveless flow switching, droplet generation and particle manipulation. We demonstrate those functions and also suggest further potential biological applications which can be accomplished by the proposed control framework.

Tuning-free controller to accurately regulate flow rates in a microfluidic network

PubMed Central

Heo, Young Jin; Kang, Junsu; Kim, Min Jun; Chung, Wan Kyun

2016-01-01

We describe a control algorithm that can improve accuracy and stability of flow regulation in a microfluidic network that uses a conventional pressure pump system. The algorithm enables simultaneous and independent control of fluid flows in multiple micro-channels of a microfluidic network, but does not require any model parameters or tuning process. We investigate robustness and optimality of the proposed control algorithm and those are verified by simulations and experiments. In addition, the control algorithm is compared with a conventional PID controller to show that the proposed control algorithm resolves critical problems induced by the PID control. The capability of the control algorithm can be used not only in high-precision flow regulation in the presence of disturbance, but in some useful functions for lab-on-a-chip devices such as regulation of volumetric flow rate, interface position control of two laminar flows, valveless flow switching, droplet generation and particle manipulation. We demonstrate those functions and also suggest further potential biological applications which can be accomplished by the proposed control framework. PMID:26987587

Design of an FPGA-based electronic flow regulator (EFR) for spacecraft propulsion system

NASA Astrophysics Data System (ADS)

Manikandan, J.; Jayaraman, M.; Jayachandran, M.

2011-02-01

This paper describes a scheme for electronically regulating the flow of propellant to the thruster from a high-pressure storage tank used in spacecraft application. Precise flow delivery of propellant to thrusters ensures propulsion system operation at best efficiency by maximizing the propellant and power utilization for the mission. The proposed field programmable gate array (FPGA) based electronic flow regulator (EFR) is used to ensure precise flow of propellant to the thrusters from a high-pressure storage tank used in spacecraft application. This paper presents hardware and software design of electronic flow regulator and implementation of the regulation logic onto an FPGA.Motivation for proposed FPGA-based electronic flow regulation is on the disadvantages of conventional approach of using analog circuits. Digital flow regulation overcomes the analog equivalent as digital circuits are highly flexible, are not much affected due to noise, accurate performance is repeatable, interface is easier to computers, storing facilities are possible and finally failure rate of digital circuits is less. FPGA has certain advantages over ASIC and microprocessor/micro-controller that motivated us to opt for FPGA-based electronic flow regulator. Also the control algorithm being software, it is well modifiable without changing the hardware. This scheme is simple enough to adopt for a wide range of applications, where the flow is to be regulated for efficient operation.The proposed scheme is based on a space-qualified re-configurable field programmable gate arrays (FPGA) and hybrid micro circuit (HMC). A graphical user interface (GUI) based application software is also developed for debugging, monitoring and controlling the electronic flow regulator from PC COM port.

Control of DC gas flow in a single-stage double-inlet pulse tube cooler

NASA Astrophysics Data System (ADS)

Wang, C.; Thummes, G.; Heiden, C.

The use of double-inlet mode in the pulse tube cooler opens up a possibility of DC gas flow circulating around the regenerator and pulse tube. Numerical analysis shows that effects of DC flow in a single-stage pulse tube cooler are different in some aspects from that in a 4 K pulse tube cooler. For highest cooler efficiency, DC flow should be compensated to a small value, i.e. DC flow over average AC flow at regenerator inlet should be in the range -0.0013 to +0.00016. Dual valves with reversed asymmetric geometries were used for the double-inlet bypass to control the DC flow in this paper. The experiment, performed in a single-stage double-inlet pulse tube cooler, verified that the cooler performance can be significantly improved by precisely controlling the DC flow.

Evaluating Modern Defenses Against Control Flow Hijacking

DTIC Science & Technology

2015-09-01

unsound and could introduce false negatives (opening up another possible set of attacks). CFG Construction using DSA We next evaluate the precision of CFG...Evaluating Modern Defenses Against Control Flow Hijacking by Ulziibayar Otgonbaatar Submitted to the Department of Electrical Engineering and...Computer Science in partial fulfillment of the requirements for the degree of Master of Science in Computer Science and Engineering at the MASSACHUSETTS

Advanced technologies and devices for inhalational anesthetic drug dosing.

PubMed

Meyer, J-U; Kullik, G; Wruck, N; Kück, K; Manigel, J

2008-01-01

Technological advances in micromechanics, optical sensing, and computing have led to innovative and reliable concepts of precise dosing and sensing of modern volatile anesthetics. Mixing of saturated desflurane flow with fresh gas flow (FGF) requires differential pressure sensing between the two circuits for precise delivery. The medical gas xenon is administered most economically in a closed circuit breathing system. Sensing of xenon in the breathing system is achieved with miniaturized and unique gas detector systems. Innovative sensing principles such as thermal conductivity and sound velocity are applied. The combination of direct injection of volatile anesthetics and low-flow in a closed circuit system requires simultaneous sensing of the inhaled and exhaled gas concentrations. When anesthetic conserving devices are used for sedation with volatile anesthetics, regular gas concentration monitoring is advised. High minimal alveolar concentration (MAC) of some anesthetics and low-flow conditions bear the risk of hypoxic gas delivery. Oxygen sensing based on paramagnetic thermal transduction has become the choice when long lifetime and one-time calibration are required. Compact design of beam splitters, infrared filters, and detectors have led to multiple spectra detector systems that fit in thimble-sized housings. Response times of less than 500 ms allow systems to distinguish inhaled from exhaled gas concentrations. The compact gas detector systems are a prerequisite to provide "quantitative anesthesia" in closed circuit feedback-controlled breathing systems. Advanced anesthesia devices in closed circuit mode employ multiple feedback systems. Multiple feedbacks include controls of volume, concentrations of anesthetics, and concentration of oxygen with a corresponding safety system. In the ideal case, the feedback system delivers precisely what the patient is consuming. In this chapter, we introduce advanced technologies and device concepts for delivering inhalational anesthetic drugs. First, modern vaporizers are described with special attention to the particularities of delivering desflurane. Delivery of xenon is presented, followed by a discussion of direct injection of volatile anesthetics and of a device designed to conserve anesthetic drugs. Next, innovative sensing technologies are presented for reliable control and precise metering of the delivered volatile anesthetics. Finally, we discuss the technical challenges of automatic control in low-flow and closed circuit breathing systems in anesthesia.

Design and Implementation of Automatic Air Flow Rate Control System

NASA Astrophysics Data System (ADS)

Akbar, A.; Saputra, C.; Munir, M. M.; Khairurrijal

2016-08-01

Venturimeter is an apparatus that can be used to measure the air flow rate. In this experiment we designed a venturimeter which equipped with a valve that is used to control the air flow rate. The difference of pressure between the cross sections was measured with the differential pressure sensor GA 100-015WD which can calculate the difference of pressures from 0 to 3737.33 Pa. A 42M048C Z36 stepper motor was used to control the valve. The precision of this motor rotation is about 0.15 °. A Graphical User Interface (GUI) was developed to monitor and set the value of flow rate then an 8-bit microcontroller was used to process the control system In this experiment- the venturimeter has been examined to get the optimal parameter of controller. The results show that the controller can set the stable output air flow rate.

System automatically supplies precise analytical samples of high-pressure gases

NASA Technical Reports Server (NTRS)

Langdon, W. M.

1967-01-01

High-pressure-reducing and flow-stabilization system delivers analytical gas samples from a gas supply. The system employs parallel capillary restrictors for pressure reduction and downstream throttling valves for flow control. It is used in conjunction with a sampling valve and minimizes alterations of the sampled gas.

Silicon microfluidic flow focusing devices for the production of size-controlled PLGA based drug loaded microparticles.

PubMed

Keohane, Kieran; Brennan, Des; Galvin, Paul; Griffin, Brendan T

2014-06-05

The increasing realisation of the impact of size and surface properties on the bio-distribution of drug loaded colloidal particles has driven the application of micro fabrication technologies for the precise engineering of drug loaded microparticles. This paper demonstrates an alternative approach for producing size controlled drug loaded PLGA based microparticles using silicon Microfluidic Flow Focusing Devices (MFFDs). Based on the precise geometry and dimensions of the flow focusing channel, microparticle size was successfully optimised by modifying the polymer type, disperse phase (Qd) flow rate, and continuous phase (Qc) flow rate. The microparticles produced ranged in sizes from 5 to 50 μm and were highly monodisperse (coefficient of variation <5%). A comparison of Ciclosporin (CsA) loaded PLGA microparticles produced by MFFDs vs conventional production techniques was also performed. MFFDs produced microparticles with a narrower size distribution profile, relative to the conventional approaches. In-vitro release kinetics of CsA was found to be influenced by the production technique, with the MFFD approach demonstrating the slowest rate of release over 7 days (4.99 ± 0.26%). Finally, MFFDs were utilised to produce pegylated microparticles using the block co-polymer, PEG-PLGA. In contrast to the smooth microparticles produced using PLGA, PEG-PLGA microparticles displayed a highly porous surface morphology and rapid CsA release, with 85 ± 6.68% CsA released after 24h. The findings from this study demonstrate the utility of silicon MFFDs for the precise control of size and surface morphology of PLGA based microparticles with potential drug delivery applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Precision forging technology for aluminum alloy

NASA Astrophysics Data System (ADS)

Deng, Lei; Wang, Xinyun; Jin, Junsong; Xia, Juchen

2018-03-01

Aluminum alloy is a preferred metal material for lightweight part manufacturing in aerospace, automobile, and weapon industries due to its good physical properties, such as low density, high specific strength, and good corrosion resistance. However, during forging processes, underfilling, folding, broken streamline, crack, coarse grain, and other macro- or microdefects are easily generated because of the deformation characteristics of aluminum alloys, including narrow forgeable temperature region, fast heat dissipation to dies, strong adhesion, high strain rate sensitivity, and large flow resistance. Thus, it is seriously restricted for the forged part to obtain precision shape and enhanced property. In this paper, progresses in precision forging technologies of aluminum alloy parts were reviewed. Several advanced precision forging technologies have been developed, including closed die forging, isothermal die forging, local loading forging, metal flow forging with relief cavity, auxiliary force or vibration loading, casting-forging hybrid forming, and stamping-forging hybrid forming. High-precision aluminum alloy parts can be realized by controlling the forging processes and parameters or combining precision forging technologies with other forming technologies. The development of these technologies is beneficial to promote the application of aluminum alloys in manufacturing of lightweight parts.

Spontaneous oscillations in microfluidic networks

NASA Astrophysics Data System (ADS)

Case, Daniel; Angilella, Jean-Regis; Motter, Adilson

2017-11-01

Precisely controlling flows within microfluidic systems is often difficult which typically results in systems being heavily reliant on numerous external pumps and computers. Here, I present a simple microfluidic network that exhibits flow rate switching, bistablity, and spontaneous oscillations controlled by a single pressure. That is, by solely changing the driving pressure, it is possible to switch between an oscillating and steady flow state. Such functionality does not rely on external hardware and may even serve as an on-chip memory or timing mechanism. I use an analytic model and rigorous fluid dynamics simulations to show these results.

MASS SPECTROMETER LEAK

DOEpatents

Shields, W.R.

1960-10-18

An improved valve is described for precisely regulating the flow of a sample fluid to be analyzed, such as in a mass spectrometer, where a gas sample is allowed to "leak" into an evacuated region at a very low, controlled rate. The flow regulating valve controls minute flow of gases by allowing the gas to diffuse between two mating surfaces. The structure of the valve is such as to prevent the corrosive feed gas from contacting the bellows which is employed in the operation of the valve, thus preventing deterioration of the bellows.

Composite adaptive control of belt polishing force for aero-engine blade

NASA Astrophysics Data System (ADS)

Zhsao, Pengbing; Shi, Yaoyao

2013-09-01

The existing methods for blade polishing mainly focus on robot polishing and manual grinding. Due to the difficulty in high-precision control of the polishing force, the blade surface precision is very low in robot polishing, in particular, quality of the inlet and exhaust edges can not satisfy the processing requirements. Manual grinding has low efficiency, high labor intensity and unstable processing quality, moreover, the polished surface is vulnerable to burn, and the surface precision and integrity are difficult to ensure. In order to further improve the profile accuracy and surface quality, a pneumatic flexible polishing force-exerting mechanism is designed and a dual-mode switching composite adaptive control(DSCAC) strategy is proposed, which combines Bang-Bang control and model reference adaptive control based on fuzzy neural network(MRACFNN) together. By the mode decision-making mechanism, Bang-Bang control is used to track the control command signal quickly when the actual polishing force is far away from the target value, and MRACFNN is utilized in smaller error ranges to improve the system robustness and control precision. Based on the mathematical model of the force-exerting mechanism, simulation analysis is implemented on DSCAC. Simulation results show that the output polishing force can better track the given signal. Finally, the blade polishing experiments are carried out on the designed polishing equipment. Experimental results show that DSCAC can effectively mitigate the influence of gas compressibility, valve dead-time effect, valve nonlinear flow, cylinder friction, measurement noise and other interference on the control precision of polishing force, which has high control precision, strong robustness, strong anti-interference ability and other advantages compared with MRACFNN. The proposed research achieves high-precision control of the polishing force, effectively improves the blade machining precision and surface consistency, and significantly reduces the surface roughness.

Design of a Single-Cell Positioning Controller Using Electroosmotic Flow and Image Processing

PubMed Central

Ay, Chyung; Young, Chao-Wang; Chen, Jhong-Yin

2013-01-01

The objective of the current research was not only to provide a fast and automatic positioning platform for single cells, but also improved biomolecular manipulation techniques. In this study, an automatic platform for cell positioning using electroosmotic flow and image processing technology was designed. The platform was developed using a PCI image acquisition interface card for capturing images from a microscope and then transferring them to a computer using human-machine interface software. This software was designed by the Laboratory Virtual Instrument Engineering Workbench, a graphical language for finding cell positions and viewing the driving trace, and the fuzzy logic method for controlling the voltage or time of an electric field. After experiments on real human leukemic cells (U-937), the success of the cell positioning rate achieved by controlling the voltage factor reaches 100% within 5 s. A greater precision is obtained when controlling the time factor, whereby the success rate reaches 100% within 28 s. Advantages in both high speed and high precision are attained if these two voltage and time control methods are combined. The control speed with the combined method is about 5.18 times greater than that achieved by the time method, and the control precision with the combined method is more than five times greater than that achieved by the voltage method. PMID:23698272

Nanophotonic Trapping for Precise Manipulation of Biomolecular Arrays

PubMed Central

Soltani, Mohammad; Lin, Jun; Forties, Robert A.; Inman, James T.; Saraf, Summer N.; Fulbright, Robert M.; Lipson, Michal; Wang, Michelle D.

2014-01-01

Optical trapping is a powerful manipulation and measurement technique widely employed in the biological and materials sciences1–8. Miniaturizing optical trap instruments onto optofluidic platforms holds promise for high throughput lab-on-chip applications9–16. However, a persistent challenge with existing optofluidic devices has been controlled and precise manipulation of trapped particles. Here we report a new class of on-chip optical trapping devices. Using photonic interference functionalities, an array of stable, three-dimensional on-chip optical traps is formed at the antinodes of a standing-wave evanescent field on a nanophotonic waveguide. By employing the thermo-optic effect via integrated electric microheaters, the traps can be repositioned at high speed (~ 30 kHz) with nanometer precision. We demonstrate sorting and manipulation of individual DNA molecules. In conjunction with laminar flows and fluorescence, we also show precise control of the chemical environment of a sample with simultaneous monitoring. Such a controllable trapping device has the potential for high-throughput precision measurements on chip. PMID:24776649

Nanophotonic trapping for precise manipulation of biomolecular arrays.

PubMed

Soltani, Mohammad; Lin, Jun; Forties, Robert A; Inman, James T; Saraf, Summer N; Fulbright, Robert M; Lipson, Michal; Wang, Michelle D

2014-06-01

Optical trapping is a powerful manipulation and measurement technique widely used in the biological and materials sciences. Miniaturizing optical trap instruments onto optofluidic platforms holds promise for high-throughput lab-on-a-chip applications. However, a persistent challenge with existing optofluidic devices has been achieving controlled and precise manipulation of trapped particles. Here, we report a new class of on-chip optical trapping devices. Using photonic interference functionalities, an array of stable, three-dimensional on-chip optical traps is formed at the antinodes of a standing-wave evanescent field on a nanophotonic waveguide. By employing the thermo-optic effect via integrated electric microheaters, the traps can be repositioned at high speed (∼30 kHz) with nanometre precision. We demonstrate sorting and manipulation of individual DNA molecules. In conjunction with laminar flows and fluorescence, we also show precise control of the chemical environment of a sample with simultaneous monitoring. Such a controllable trapping device has the potential to achieve high-throughput precision measurements on chip.

A completely automated flow, heat-capacity, calorimeter for use at high temperatures and pressures

NASA Astrophysics Data System (ADS)

Rogers, P. S. Z.; Sandarusi, Jamal

1990-11-01

An automated, flow calorimeter has been constructed to measure the isobaric heat capacities of concentrated, aqueous electrolyte solutions using a differential calorimetry technique. The calorimeter is capable of operation to 700 K and 40 MPa with a measurement accuracy of 0.03% relative to the heat capacity of the pure reference fluid (water). A novel design encloses the calorimeter within a double set of separately controlled, copper, adiabatic shields that minimize calorimeter heat losses and precisely control the temperature of the inlet fluids. A multistage preheat train, used to efficiently heat the flowing fluid, includes a counter-current heat exchanger for the inlet and outlet fluid streams in tandem with two calorimeter preheaters. Complete system automation is accomplished with a distributed control scheme using multiple processors, allowing the major control tasks of calorimeter operation and control, data logging and display, and pump control to be performed simultaneously. A sophisticated pumping strategy for the two separate syringe pumps allows continuous fluid delivery. This automation system enables the calorimeter to operate unattended except for the reloading of sample fluids. In addition, automation has allowed the development and implementation of an improved heat loss calibration method that provides calorimeter calibration with absolute accuracy comparable to the overall measurement precision, even for very concentrated solutions.

Droplet-counting Microtitration System for Precise On-site Analysis.

PubMed

Kawakubo, Susumu; Omori, Taichi; Suzuki, Yasutada; Ueta, Ikuo

2018-01-01

A new microtitration system based on the counting of titrant droplets has been developed for precise on-site analysis. The dropping rate was controlled by inserting a capillary tube as a flow resistance in a laboratory-made micropipette. The error of titration was 3% in a simulated titration with 20 droplets. The pre-addition of a titrant was proposed for precise titration within an error of 0.5%. The analytical performances were evaluated for chelate titration, redox titration and acid-base titration.

Preliminary control system design and analysis for the Space Station Furnace Facility thermal control system

NASA Technical Reports Server (NTRS)

Jackson, M. E.

1995-01-01

This report presents the Space Station Furnace Facility (SSFF) thermal control system (TCS) preliminary control system design and analysis. The SSFF provides the necessary core systems to operate various materials processing furnaces. The TCS is defined as one of the core systems, and its function is to collect excess heat from furnaces and to provide precise cold temperature control of components and of certain furnace zones. Physical interconnection of parallel thermal control subsystems through a common pump implies the description of the TCS by coupled nonlinear differential equations in pressure and flow. This report formulates the system equations and develops the controllers that cause the interconnected subsystems to satisfy flow rate tracking requirements. Extensive digital simulation results are presented to show the flow rate tracking performance.

Quantifying the Hydraulic Roughness of Vegetation using Physical Modelling and Through-Water Terrestrial Laser Scanning.

NASA Astrophysics Data System (ADS)

Vasilopoulos, G.; Leyland, J.; Nield, J. M.

2016-12-01

Plants function as large-scale, flexible obstacles that exert additional drag on water flows, affecting local scale turbulence and the structure of the boundary layer. Hence, vegetation plays a significant role controlling surface water flows and modulating geomorphic change. This makes it an important, but often under considered, component when undertaking flood or erosion control actions, or designing river restoration strategies. Vegetative drag varies depending on flow conditions and the associated vegetation structure and temporary reconfiguration of the plant. Whilst several approaches have been developed to describe this relationship, they have been limited due to the difficulty of accurately and precisely characterising the vegetation itself, especially when it is submerged in flow. In practice, vegetative drag is commonly expressed through bulk parameters that are typically derived from lookup tables. Terrestrial Laser Scanning (TLS) has the ability to capture the surface of in situ objects as 3D point clouds, at high resolution (mm), precision and accuracy, even when submerged in water. This allows for the development of workflows capable of quantifying vegetation structure in 3D from dense TLS point cloud data. A physical modelling experiment investigated the impact of a series of structurally variable plants on flow at three different velocities. Acoustic Doppler Velocimetry (ADV) was employed to measure the velocity field and the corresponding fluvial drag of the vegetation was estimated using a bulk roughness function calculated from precise measurements of the water surface slope. Simultaneously, through-water TLS was employed to capture snapshots of plant deformation and distinguish plant structure during flow, using a porosity approach. Although plant type is important, we find a good relationship between plant structure, drag and adjustments of the velocity field.

Continuous flow chemistry: a discovery tool for new chemical reactivity patterns.

PubMed

Hartwig, Jan; Metternich, Jan B; Nikbin, Nikzad; Kirschning, Andreas; Ley, Steven V

2014-06-14

Continuous flow chemistry as a process intensification tool is well known. However, its ability to enable chemists to perform reactions which are not possible in batch is less well studied or understood. Here we present an example, where a new reactivity pattern and extended reaction scope has been achieved by transferring a reaction from batch mode to flow. This new reactivity can be explained by suppressing back mixing and precise control of temperature in a flow reactor set up.

Three dimensional drop tracking flow chamber for coalescence studies

DOE PAGES

Grillet, Anne M.; Brooks, Carlton F.; Bourdon, Chris J.; ...

2007-09-12

Here, we have developed a novel flow chamber which imposes a controlled axisymmetric stagnation flow to enable the study of external flow effects on coalescence dynamics. This system allows for the first time the precise positioning of a drop in a three dimensional flow and additionally enforces a highly symmetric flow around the drop. We focus on the study of a single drop approaching a stationary flat plane as this is analogous to two drops approaching each other. A single drop is created and then guided along the unsteady center line of a stagnation flow. The real time computer controlmore » algorithm analyzes video images of the drop in two orthogonal planes and manipulates flow restricting valves along the four outlets of the flow. We demonstrate using particle image velocimetry that the computer control not only controls the drop position but also ensures a symmetric flow inside the flow chamber. Finally, this chamber will enable a detailed investigation of the drainage of the thin film between the drop and the lower surface in order to probe the effect of external flow on coalescence.« less

Active porous transition towards spatiotemporal control of molecular flow in a crystal membrane

NASA Astrophysics Data System (ADS)

Takasaki, Yuichi; Takamizawa, Satoshi

2015-11-01

Fluidic control is an essential technology widely found in processes such as flood control in land irrigation and cell metabolism in biological tissues. In any fluidic control system, valve function is the key mechanism used to actively regulate flow and miniaturization of fluidic regulation with precise workability will be particularly vital in the development of microfluidic control. The concept of crystal engineering is alternative to processing technology in microstructure construction, as the ultimate microfluidic devices must provide molecular level control. Consequently, microporous crystals can instantly be converted to microfluidic devices if introduced in an active transformability of porous structure and geometry. Here we show that the introduction of a stress-induced martensitic transition mechanism converts a microporous molecular crystal into an active fluidic device with spatiotemporal molecular flow controllability through mechanical reorientation of subnanometre channels.

Molecular transport through capillaries made with atomic-scale precision

NASA Astrophysics Data System (ADS)

Radha, B.; Esfandiar, A.; Wang, F. C.; Rooney, A. P.; Gopinadhan, K.; Keerthi, A.; Mishchenko, A.; Janardanan, A.; Blake, P.; Fumagalli, L.; Lozada-Hidalgo, M.; Garaj, S.; Haigh, S. J.; Grigorieva, I. V.; Wu, H. A.; Geim, A. K.

2016-10-01

Nanometre-scale pores and capillaries have long been studied because of their importance in many natural phenomena and their use in numerous applications. A more recent development is the ability to fabricate artificial capillaries with nanometre dimensions, which has enabled new research on molecular transport and led to the emergence of nanofluidics. But surface roughness in particular makes it challenging to produce capillaries with precisely controlled dimensions at this spatial scale. Here we report the fabrication of narrow and smooth capillaries through van der Waals assembly, with atomically flat sheets at the top and bottom separated by spacers made of two-dimensional crystals with a precisely controlled number of layers. We use graphene and its multilayers as archetypal two-dimensional materials to demonstrate this technology, which produces structures that can be viewed as if individual atomic planes had been removed from a bulk crystal to leave behind flat voids of a height chosen with atomic-scale precision. Water transport through the channels, ranging in height from one to several dozen atomic planes, is characterized by unexpectedly fast flow (up to 1 metre per second) that we attribute to high capillary pressures (about 1,000 bar) and large slip lengths. For channels that accommodate only a few layers of water, the flow exhibits a marked enhancement that we associate with an increased structural order in nanoconfined water. Our work opens up an avenue to making capillaries and cavities with sizes tunable to ångström precision, and with permeation properties further controlled through a wide choice of atomically flat materials available for channel walls.

Generation of Microbubbles with Applications to Industry and Medicine

NASA Astrophysics Data System (ADS)

Rodríguez-Rodríguez, Javier; Sevilla, Alejandro; Martínez-Bazán, Carlos; Gordillo, José Manuel

2015-01-01

We provide a comprehensive and systematic description of the diverse microbubble generation methods recently developed to satisfy emerging technological, pharmaceutical, and medical demands. We first introduce a theoretical framework unifying the physics of bubble formation in the wide variety of existing types of generators. These devices are then classified according to the way the bubbling process is controlled: outer liquid flows (e.g., coflows, cross flows, and flow-focusing flows), acoustic forcing, and electric fields. We also address modern techniques developed to produce bubbles coated with surfactants and liquid shells. The stringent requirements to precisely control the bubbling frequency, the bubble size, and the properties of the coating make microfluidics the natural choice to implement such techniques.

The NASA Langley Research Center 0.3-meter transonic cryogenic tunnel T-P/Re-M controller manual

NASA Technical Reports Server (NTRS)

Balakrishna, S.; Kilgore, W. Allen

1989-01-01

A new microcomputer based controller for the 0.3-m Transonic Cryogenic Tunnel (TCT) has been commissioned in 1988 and has reliably operated for more than a year. The tunnel stagnation pressure, gas stagnation temperature, tunnel wall structural temperature and flow Mach number are precisely controlled by the new controller in a stable manner. The tunnel control hardware, software, and the flow chart to assist in calibration of the sensors, actuators, and the controller real time functions are described. The software installation details are also presented. The report serves as the maintenance and trouble shooting manual for the 0.3-m TCT controller.

Design and Evaluation of a Proxy-Based Monitoring System for OpenFlow Networks.

PubMed

Taniguchi, Yoshiaki; Tsutsumi, Hiroaki; Iguchi, Nobukazu; Watanabe, Kenzi

2016-01-01

Software-Defined Networking (SDN) has attracted attention along with the popularization of cloud environment and server virtualization. In SDN, the control plane and the data plane are decoupled so that the logical topology and routing control can be configured dynamically depending on network conditions. To obtain network conditions precisely, a network monitoring mechanism is necessary. In this paper, we focus on OpenFlow which is a core technology to realize SDN. We propose, design, implement, and evaluate a network monitoring system for OpenFlow networks. Our proposed system acts as a proxy between an OpenFlow controller and OpenFlow switches. Through experimental evaluations, we confirm that our proposed system can capture packets and monitor traffic information depending on administrator's configuration. In addition, we show that our proposed system does not influence significant performance degradation to overall network performance.

Design and Evaluation of a Proxy-Based Monitoring System for OpenFlow Networks

PubMed Central

Taniguchi, Yoshiaki; Tsutsumi, Hiroaki; Iguchi, Nobukazu; Watanabe, Kenzi

2016-01-01

Software-Defined Networking (SDN) has attracted attention along with the popularization of cloud environment and server virtualization. In SDN, the control plane and the data plane are decoupled so that the logical topology and routing control can be configured dynamically depending on network conditions. To obtain network conditions precisely, a network monitoring mechanism is necessary. In this paper, we focus on OpenFlow which is a core technology to realize SDN. We propose, design, implement, and evaluate a network monitoring system for OpenFlow networks. Our proposed system acts as a proxy between an OpenFlow controller and OpenFlow switches. Through experimental evaluations, we confirm that our proposed system can capture packets and monitor traffic information depending on administrator's configuration. In addition, we show that our proposed system does not influence significant performance degradation to overall network performance. PMID:27006977

Enabling Technologies for Microfluidic Flow Control and Detection

NASA Astrophysics Data System (ADS)

Leslie, Daniel Christopher

Advances in microfluidic technologies have expanded conventional chemical and biological techniques to the point where we can envision rapid, inexpensive and portable analysis. Among the numerous challenges in the development of portable, chip-based technologies are simple flow control and detection strategies, which will be essential to widespread acceptance and implementation at both the point-of-care and in locales with limited facilities/resources. The research presented in this dissertation is focused on the development of precise flow control techniques and new, simplified detection technologies aimed at addressing these challenges. An introduction to the concepts important to microfluidics and a brief history to the field are presented in Chapter 1. Chapter 2 will present the development of a technique for the precise control of small volumes of liquids, where well-studied electrical circuit concepts are employed to create frequency-dependent microfluidic circuits. In this system, elastomeric thin films act as fluidic capacitors and diodes, which, when combined with resistors (channels), make fluidic circuits that are described by analytical models. Metering of two separate chemical inputs with a single oscillatory pneumatic control line is demonstrated by combining simple fluidic circuits (i.e., band-pass filters) to significantly reduce the external hardware required for microfluidic flow control. In order to quantify multiple flow profiles in microfluidic circuits, a novel multiplexed flow measurement method using visible dyes is introduced in Chapter 3 and rapidly determines individual flow in connected channels, post-fabrication device quality and solution viscosity. Another thrust of this dissertation research has been to develop miniaturized bioanalytical systems. Chapter 4 describes the adaption of a nucleic-acid-tagged antibody protein detection reaction to a microfluidic platform for detection of down to 5 E. coli O157:H7 cells. Furthermore, a completely non-contact temperature control platform is developed in Chapter 5 for forensic human identification reactions, based on interferometric temperature sensing and infrared-mediated heating, which simplifies the microfluidic device and its operation. Finally, possible future directions are outlined in Chapter 6 including further simplification of microfluidic instrumentation.

End-to-End Flow Control for Visual-Haptic Communication under Bandwidth Change

NASA Astrophysics Data System (ADS)

Yashiro, Daisuke; Tian, Dapeng; Yakoh, Takahiro

This paper proposes an end-to-end flow controller for visual-haptic communication. A visual-haptic communication system transmits non-real-time packets, which contain large-size visual data, and real-time packets, which contain small-size haptic data. When the transmission rate of visual data exceeds the communication bandwidth, the visual-haptic communication system becomes unstable owing to buffer overflow. To solve this problem, an end-to-end flow controller is proposed. This controller determines the optimal transmission rate of visual data on the basis of the traffic conditions, which are estimated by the packets for haptic communication. Experimental results confirm that in the proposed method, a short packet-sending interval and a short delay are achieved under bandwidth change, and thus, high-precision visual-haptic communication is realized.

The CO2 stimulus for cerebrovascular reactivity: Fixing inspired concentrations vs. targeting end-tidal partial pressures.

PubMed

Fisher, Joseph A

2016-06-01

Cerebrovascular reactivity (CVR) studies have elucidated the physiology and pathophysiology of cerebral blood flow regulation. A non-invasive, high spatial resolution approach uses carbon dioxide (CO2) as the vasoactive stimulus and magnetic resonance techniques to estimate the cerebral blood flow response. CVR is assessed as the ratio response change to stimulus change. Precise control of the stimulus is sought to minimize CVR variability between tests, and show functional differences. Computerized methods targeting end-tidal CO2 partial pressures are precise, but expensive. Simpler, improvised methods that fix the inspired CO2 concentrations have been recommended as less expensive, and so more widely accessible. However, these methods have drawbacks that have not been previously presented by those that advocate their use, or those that employ them in their studies. As one of the developers of a computerized method, I provide my perspective on the trade-offs between these two methods. The main concern is that declaring the precision of fixed inspired concentration of CO2 is misleading: it does not, as implied, translate to precise control of the actual vasoactive stimulus - the arterial partial pressure of CO2 The inherent test-to-test, and therefore subject-to-subject variability, precludes clinical application of findings. Moreover, improvised methods imply widespread duplication of development, assembly time and costs, yet lack uniformity and quality control. A tabular comparison between approaches is provided. © The Author(s) 2016.

Testing of active heat sink for advanced high-power laser diodes

NASA Astrophysics Data System (ADS)

Vetrovec, John; Copeland, Drew A.; Feeler, Ryan; Junghans, Jeremy

2011-03-01

We report on the development of a novel active heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink employs convective heat transfer by a liquid metal flowing at high speed inside a miniature sealed flow loop. Liquid metal flow in the loop is maintained electromagnetically without any moving parts. Thermal conductance of the heat sink is electronically adjustable, allowing for precise control of diode temperature and the laser light wavelength. This paper presents the principles and challenges of liquid metal cooling, and data from testing at high heat flux and high heat loads.

Study on the Automatic Detection Method and System of Multifunctional Hydrocephalus Shunt

NASA Astrophysics Data System (ADS)

Sun, Xuan; Wang, Guangzhen; Dong, Quancheng; Li, Yuzhong

2017-07-01

Aiming to the difficulty of micro pressure detection and the difficulty of micro flow control in the testing process of hydrocephalus shunt, the principle of the shunt performance detection was analyzed.In this study, the author analyzed the principle of several items of shunt performance detection,and used advanced micro pressure sensor and micro flow peristaltic pump to overcome the micro pressure detection and micro flow control technology.At the same time,This study also puted many common experimental projects integrated, and successfully developed the automatic detection system for a shunt performance detection function, to achieve a test with high precision, high efficiency and automation.

Precision Adjustable Liquid Regulator (ALR)

NASA Astrophysics Data System (ADS)

Meinhold, R.; Parker, M.

2004-10-01

A passive mechanical regulator has been developed for the control of fuel or oxidizer flow to a 450N class bipropellant engine for use on commercial and interplanetary spacecraft. There are several potential benefits to the propulsion system, depending on mission requirements and spacecraft design. This system design enables more precise control of main engine mixture ratio and inlet pressure, and simplifies the pressurization system by transferring the function of main engine flow rate control from the pressurization/propellant tank assemblies, to a single component, the ALR. This design can also reduce the thermal control requirements on the propellant tanks, avoid costly Qualification testing of biprop engines for missions with more stringent requirements, and reduce the overall propulsion system mass and power usage. In order to realize these benefits, the ALR must meet stringent design requirements. The main advantage of this regulator over other units available in the market is that it can regulate about its nominal set point to within +/-0.85%, and change its regulation set point in flight +/-4% about that nominal point. The set point change is handled actively via a stepper motor driven actuator, which converts rotary into linear motion to affect the spring preload acting on the regulator. Once adjusted to a particular set point, the actuator remains in its final position unpowered, and the regulator passively maintains outlet pressure. The very precise outlet regulation pressure is possible due to new technology developed by Moog, Inc. which reduces typical regulator mechanical hysteresis to near zero. The ALR requirements specified an outlet pressure set point range from 225 to 255 psi, and equivalent water flow rates required were in the 0.17 lb/sec range. The regulation output pressure is maintained at +/-2 psi about the set point from a P (delta or differential pressure) of 20 to over 100 psid. Maximum upstream system pressure was specified at 320 psi. The regulator is fault tolerant in that it was purposely designed with no shutoff capability, such that the minimum flow position of the poppet still allows the subsystem to provide adequate flow to the main engine for basic operation.

Bumblebee flight performance in environments of different proximity.

PubMed

Linander, Nellie; Baird, Emily; Dacke, Marie

2016-02-01

Flying animals are capable of navigating through environments of different complexity with high precision. To control their flight when negotiating narrow tunnels, bees and birds use the magnitude of apparent image motion (known as optic flow) generated by the walls. In their natural habitat, however, these animals would encounter both cluttered and open environments. Here, we investigate how large changes in the proximity of nearby surfaces affect optic flow-based flight control strategies. We trained bumblebees to fly along a flight and recorded how the distance between the walls--from 60 cm to 240 cm--affected their flight control. Our results reveal that, as tunnel width increases, both lateral position and ground speed become increasingly variable. We also find that optic flow information from the ground has an increasing influence on flight control, suggesting that bumblebees measure optic flow flexibly over a large lateral and ventral field of view, depending on where the highest magnitude of optic flow occurs. A consequence of this strategy is that, when flying in narrow spaces, bumblebees use optic flow information from the nearby obstacles to control flight, while in more open spaces they rely primarily on optic flow cues from the ground.

An automatic bolus injector for use in radiotracer studies of blood flow: design and evaluation.

PubMed

Snyder, R E; Overton, T R; Boisvert, D P; Petruk, K C

1976-12-01

An electromechanical device is described which automatically injects the radiotracer bolus used in the measurement of cerebral blood flow. It consists of two electronically controlled, solenoid operated syringes, one containing the radiotracer solution and the other heparinized saline. Results are presented which show that use of the automatic bolus injector in place of hand injection leads to an improvement in the precision of measured flow values. Additional advantages of the device are discussed.

Periodicity and chaos from switched flow systems - Contrasting examples of discretely controlled continuous systems

NASA Technical Reports Server (NTRS)

Chase, Christopher; Serrano, Joseph; Ramadge, Peter J.

1993-01-01

We analyze two examples of the discrete control of a continuous variable system. These examples exhibit what may be regarded as the two extremes of complexity of the closed-loop behavior: one is eventually periodic, the other is chaotic. Our examples are derived from sampled deterministic flow models. These are of interest in their own right but have also been used as models for certain aspects of manufacturing systems. In each case, we give a precise characterization of the closed-loop behavior.

Particulate Characterization and Control Evaluation for Carbon Fiber Composite Aircraft Crash Recovery Operations

DTIC Science & Technology

2010-03-01

Advanced Composite Office, Wright-Patterson BEE Flight, and USAFSAM for their help procuring the materials and supplies needed to perform this study...through the cyclone. (Cohen & Charles S . McCammonn, 2001) The major limitation of the cyclone is that the cut curve of the cyclone does not precisely...If the pump is not precisely calibrated to the specified flow the cut point will be altered. (Cohen & Charles S . McCammonn, 2001) Once the sample

Liquid Bismuth Feed System for Electric Propulsion

NASA Technical Reports Server (NTRS)

Markusic, T. E.; Polzin, K. A.; Stanojev, B. J.

2006-01-01

Operation of Hall thrusters with bismuth propellant has been shown to be a promising path toward high-power, high-performance, long-lifetime electric propulsion for spaceflight missions. For example, the VHITAL project aims td accurately, experimentally assess the performance characteristics of 10 kW-class bismuth-fed Hall thrusters - in order to validate earlier results and resuscitate a promising technology that has been relatively dormant for about two decades. A critical element of these tests will be the precise metering of propellant to the thruster, since performance cannot be accurately assessed without an accurate accounting of mass flow rate. Earlier work used a pre/post-test propellant weighing scheme that did not provide any real-time measurement of mass flow rate while the thruster was firing, and makes subsequent performance calculations difficult. The motivation of the present work was to develop a precision liquid bismuth Propellant Management System (PMS) that provides real-time propellant mass flow rate measurement and control, enabling accurate thruster performance measurements. Additionally, our approach emphasizes the development of new liquid metal flow control components and, hence, will establish a basis for the future development of components for application in spaceflight. The design of various critical components in a bismuth PMS are described - reservoir, electromagnetic pump, hotspot flow sensor, and automated control system. Particular emphasis is given to material selection and high-temperature sealing techniques. Open loop calibration test results are reported, which validate the systems capability to deliver bismuth at mass flow rates ranging from 10 to 100 mg/sec with an uncertainty of less than +/- 5%. Results of integrated vaporizer/liquid PMS tests demonstrate all of the necessary elements of a complete bismuth feed system for electric propulsion.

Observing polymersome dynamics in controlled microscale flows

NASA Astrophysics Data System (ADS)

Kumar, Subhalakshmi; Shenoy, Anish; Schroeder, Charles

2015-03-01

Achieving an understanding of single particle rheology for large yet deformable particles with controlled membrane viscoelasticity is major challenge in soft materials. In this work, we directly visualize the dynamics of single polymersomes (~ 10 μm in size) in an extensional flow using optical microscopy. We generate polymer vesicular structures composed of polybutadiene-block-polyethylene oxide (PB-b-PEO) copolymers. Single polymersomes are confined near the stagnation point of a planar extensional flow using an automated microfluidic trap, thereby enabling the direct observation of polymersome dynamics under fluid flows with controlled strains and strain rates. In a series of experiments, we investigate the effect of varying elasticity in vesicular membranes on polymersome deformation, along with the impact of decreasing membrane fluidity upon increasing diblock copolymer molecular weight. Overall, we believe that this approach will enable precise characterization of the role of membrane properties on single particle rheology for deformable polymersomes.

A cautionary note on the use of some mass flow controllers

NASA Astrophysics Data System (ADS)

Weinheimer, Andrew J.; Ridley, Brian A.

1990-06-01

Commercial mass flow controllers are widely used in atmospheric research where precise and constant gas flows are required. We have determined, however, that some commonly used controllers are far more sensitive to ambient pressure than is acknowledged in the literature of the manufacturers. Since a flow error can lead directly to a measurement error of the same magnitude, this is a matter of great concern. Indeed, in our particular application, were we not aware of this problem, our measurements would be subject to a systematic error that increased with altitude (i.e., a drift), up to a factor of 2 at the highest altitudes (˜37 km). In this note we present laboratory measurements of the errors of two brands of flow controllers when operated at pressures down to a few millibars. The errors are as large as a factor of 2 to 3 and depend not simply on the ambient pressure at a given time, but also on the pressure history. In addition there is a large dependence on flow setting. In light of these flow errors, some past measurements of chemical species in the stratosphere will need to be revised.

Achieving high time-resolution with a new flow-through type analyzer for total inorganic carbon in seawater.

PubMed

Kimoto, Hideshi; Nozaki, Ken; Kudo, Setsuko; Kato, Ken; Negishi, Akira; Kayanne, Hajime

2002-03-01

A fully automated, continuous-flow-through type analyzer was developed to observe rapid changes in the concentration of total inorganic carbon (CT) in coastal zones. Seawater and an H3PO4 solution were fed into the analyzer's mixing coil by two high-precision valveless piston pumps. The CO2 was stripped from the seawater and moved into a carrier gas, using a newly developed continuous-flow-through CO2 extractor. A mass flow controller was used to assure a precise flow rate of the carrier gas. The CO2 concentration was then determined with a nondispersive infrared gas analyzer. This analyzer achieved a time-resolution of as good as 1 min. In field experiments on a shallow reef flat of Shiraho (Ishigaki Island, Southwest Japan), the analyzer detected short-term, yet extreme, variations in CT which manual sampling missed. Analytical values obtained by the analyzer on the boat were compared with those determined by potentiometric titration with a closed cell in a laboratory: CT(flow-through) = 0.980 x CT(titration) + 38.8 with r2 = 0.995 (n = 34; September 1998).

Microscale fluid transport using optically controlled marangoni effect

DOEpatents

Thundat, Thomas G [Knoxville, TN; Passian, Ali [Knoxville, TN; Farahi, Rubye H [Oak Ridge, TN

2011-05-10

Low energy light illumination and either a doped semiconductor surface or a surface-plasmon supporting surface are used in combination for manipulating a fluid on the surface in the absence of any applied electric fields or flow channels. Precise control of fluid flow is achieved by applying focused or tightly collimated low energy light to the surface-fluid interface. In the first embodiment, with an appropriate dopant level in the semiconductor substrate, optically excited charge carriers are made to move to the surface when illuminated. In a second embodiment, with a thin-film noble metal surface on a dispersive substrate, optically excited surface plasmons are created for fluid manipulation. This electrode-less optical control of the Marangoni effect provides re-configurable manipulations of fluid flow, thereby paving the way for reprogrammable microfluidic devices.

Precision-controlled elution of a 82Sr/82Rb generator for cardiac perfusion imaging with positron emission tomography

NASA Astrophysics Data System (ADS)

Klein, R.; Adler, A.; Beanlands, R. S.; de Kemp, R. A.

2007-02-01

A rubidium-82 (82Rb) elution system is described for use with positron emission tomography. Due to the short half-life of 82Rb (76 s), the system physics must be modelled precisely to account for transport delay and the associated activity decay and dispersion. Saline flow is switched between a 82Sr/82Rb generator and a bypass line to achieve a constant-activity elution of 82Rb. Pulse width modulation (PWM) of a solenoid valve is compared to simple threshold control as a means to simulate a proportional valve. A predictive-corrective control (PCC) algorithm is developed which produces a constant-activity elution within the constraints of long feedback delay and short elution time. The system model parameters are adjusted through a self-tuning algorithm to minimize error versus the requested time-activity profile. The system is self-calibrating with 2.5% repeatability, independent of generator activity and elution flow rate. Accurate 30 s constant-activity elutions of 10-70% of the total generator activity are achieved using both control methods. The combined PWM-PCC method provides significant improvement in precision and accuracy of the requested elution profiles. The 82Rb elution system produces accurate and reproducible constant-activity elution profiles of 82Rb activity, independent of parent 82Sr activity in the generator. More reproducible elution profiles may improve the quality of clinical and research PET perfusion studies using 82Rb.

Precision-controlled elution of a 82Sr/82Rb generator for cardiac perfusion imaging with positron emission tomography.

PubMed

Klein, R; Adler, A; Beanlands, R S; Dekemp, R A

2007-02-07

A rubidium-82 ((82)Rb) elution system is described for use with positron emission tomography. Due to the short half-life of (82)Rb (76 s), the system physics must be modelled precisely to account for transport delay and the associated activity decay and dispersion. Saline flow is switched between a (82)Sr/(82)Rb generator and a bypass line to achieve a constant-activity elution of (82)Rb. Pulse width modulation (PWM) of a solenoid valve is compared to simple threshold control as a means to simulate a proportional valve. A predictive-corrective control (PCC) algorithm is developed which produces a constant-activity elution within the constraints of long feedback delay and short elution time. The system model parameters are adjusted through a self-tuning algorithm to minimize error versus the requested time-activity profile. The system is self-calibrating with 2.5% repeatability, independent of generator activity and elution flow rate. Accurate 30 s constant-activity elutions of 10-70% of the total generator activity are achieved using both control methods. The combined PWM-PCC method provides significant improvement in precision and accuracy of the requested elution profiles. The (82)Rb elution system produces accurate and reproducible constant-activity elution profiles of (82)Rb activity, independent of parent (82)Sr activity in the generator. More reproducible elution profiles may improve the quality of clinical and research PET perfusion studies using (82)Rb.

Design and Evaluation of the Terminal Area Precision Scheduling and Spacing System

NASA Technical Reports Server (NTRS)

Swenson, Harry N.; Thipphavong, Jane; Sadovsky, Alex; Chen, Liang; Sullivan, Chris; Martin, Lynne

2011-01-01

This paper describes the design, development and results from a high fidelity human-in-the-loop simulation of an integrated set of trajectory-based automation tools providing precision scheduling, sequencing and controller merging and spacing functions. These integrated functions are combined into a system called the Terminal Area Precision Scheduling and Spacing (TAPSS) system. It is a strategic and tactical planning tool that provides Traffic Management Coordinators, En Route and Terminal Radar Approach Control air traffic controllers the ability to efficiently optimize the arrival capacity of a demand-impacted airport while simultaneously enabling fuel-efficient descent procedures. The TAPSS system consists of four-dimensional trajectory prediction, arrival runway balancing, aircraft separation constraint-based scheduling, traffic flow visualization and trajectory-based advisories to assist controllers in efficient metering, sequencing and spacing. The TAPSS system was evaluated and compared to today's ATC operation through extensive series of human-in-the-loop simulations for arrival flows into the Los Angeles International Airport. The test conditions included the variation of aircraft demand from a baseline of today's capacity constrained periods through 5%, 10% and 20% increases. Performance data were collected for engineering and human factor analysis and compared with similar operations both with and without the TAPSS system. The engineering data indicate operations with the TAPSS show up to a 10% increase in airport throughput during capacity constrained periods while maintaining fuel-efficient aircraft descent profiles from cruise to landing.

Development of a Mechatronic Syringe Pump to Control Fluid Flow in a Microfluidic Device Based on Polyimide Film

NASA Astrophysics Data System (ADS)

Sek Tee, Kian; Sharil Saripan, Muhammad; Yap, Hiung Yin; Fhong Soon, Chin

2017-08-01

With the advancement in microfluidic technology, fluid flow control for syringe pump is always essential. In this paper, a mechatronic syringe pump will be developed and customized to control the fluid flow in a poly-dimethylsiloxane (PDMS) microfluidic device based on a polyimide laminating film. The syringe pump is designed to drive fluid with flow rates of 100 and 1000 μl/min which intended to drive continuous fluid in a polyimide based microfluidic device. The electronic system consists of an Arduino microcontroller board and a uni-polar stepper motor. In the system, the uni-polar stepper motor was coupled to a linear slider attached to the plunger of a syringe pump. As the motor rotates, the plunger pumps the liquid out of the syringe. The accuracy of the fluid flow rate was determined by adjusting the number of micro-step/revolution to drive the stepper motor to infuse fluid into the microfluidic device. With the precise control of the electronic system, the syringe pump could accurately inject fluid volume at 100 and 1000 μl/min into a microfluidic device.

An Investigation of Slurry Fuel Combustion.

DTIC Science & Technology

1981-01-01

tit Lil’ sitas wtae f).4 mm ap.art. w w =Q L-1~ rAn Li w > 0 0- - q The propane gas flow rate was metered withi a Matlieson Model 604 rotameter and...controlled by a Harris Model 2515 pressure regulator with an output capacity of 0-0.69 MPa. The flow rate of the iydrog’en gas was metered with a...propane 3nd hydrogen flows were calibrated with a Precision Scientific Companv wet-test meter (2.83 ml/rev). The fuel drops were mounted with a

Simulation of proportional control of hydraulic actuator using digital hydraulic valves

NASA Astrophysics Data System (ADS)

Raghuraman, D. R. S.; Senthil Kumar, S.; Kalaiarasan, G.

2017-11-01

Fluid power systems using oil hydraulics in earth moving and construction equipment have been using proportional and servo control valves for a long time to achieve precise and accurate position control backed by system performance. Such valves are having feedback control in them and exhibit good response, sensitivity and fine control of the actuators. Servo valves and proportional valves are possessing less hysteresis when compared to on-off type valves, but when the servo valve spools get stuck in one position, a high frequency called as jitter is employed to bring the spool back, whereas in on-off type valves it requires lesser technology to retract the spool. Hence on-off type valves are used in a technology known as digital valve technology, which caters to precise control on slow moving loads with fast switching times and with good flow and pressure control mimicking the performance of an equivalent “proportional valve” or “servo valve”.

Experimental research on mathematical modelling and unconventional control of clinker kiln in cement plants

NASA Astrophysics Data System (ADS)

Rusu-Anghel, S.

2017-01-01

Analytical modeling of the flow of manufacturing process of the cement is difficult because of their complexity and has not resulted in sufficiently precise mathematical models. In this paper, based on a statistical model of the process and using the knowledge of human experts, was designed a fuzzy system for automatic control of clinkering process.

Modeling fluid transport in 2d paper networks

NASA Astrophysics Data System (ADS)

Tirapu Azpiroz, Jaione; Fereira Silva, Ademir; Esteves Ferreira, Matheus; Lopez Candela, William Fernando; Bryant, Peter William; Ohta, Ricardo Luis; Engel, Michael; Steiner, Mathias Bernhard

2018-02-01

Paper-based microfluidic devices offer great potential as a low-cost platform to perform chemical and biochemical tests. Commercially available formats such as dipsticks and lateral-flow test devices are widely popular as they are easy to handle and produce fast and unambiguous results. While these simple devices lack precise control over the flow to enable integration of complex functionality for multi-step processes or the ability to multiplex several tests, intense research in this area is rapidly expanding the possibilities. Modeling and simulation is increasingly more instrumental in gaining insight into the underlying physics driving the processes inside the channels, however simulation of flow in paper-based microfluidic devices has barely been explored to aid in the optimum design and prototyping of these devices for precise control of the flow. In this paper, we implement a multiphase fluid flow model through porous media for the simulation of paper imbibition of an incompressible, Newtonian fluid such as when water, urine or serum is employed. The formulation incorporates mass and momentum conservation equations under Stokes flow conditions and results in two coupled Darcy's law equations for the pressures and saturations of the wetting and non-wetting phases, further simplified to the Richard's equation for the saturation of the wetting fluid, which is then solved using a Finite Element solver. The model tracks the wetting fluid front as it displaces the non-wetting fluid by computing the time-dependent saturation of the wetting fluid. We apply this to the study of liquid transport in two-dimensional paper networks and validate against experimental data concerning the wetting dynamics of paper layouts of varying geometries.

Flow control for a paper-based microfluidic device by adjusting permeability of paper

NASA Astrophysics Data System (ADS)

Jang, Ilhoon; Kim, Gangjune; Song, Simon

2014-11-01

The paper-based microfluidics has attracted intensive attention as a prospective substitute for conventional microfluidic substrates used for a point-of-care diagnostics due to its superior advantages such as the cost effectiveness and production simplicity. Generally, a paper-based microfluidic device utilizes capillary force to drive a flow. Recent studies on flow control in such a device aimed at obtaining accurate and quantitative results by varying a channel geometry like width and length. According to the Darcy's law describing a flow in a porous media like paper, a flow rate can be adjusted the permeability of paper. In this study, we investigate a flow control method by adjusting the permeability of paper. We utilize the wax printing for the adjustment and the fabrication of paper channels. A rectangular wax pattern was printed on one inlet channel of a Y-channel geometry. By varying the brightness of the wax pattern, a relationship between the flow rate and permeability changes due to the wax was investigated. As a result, we obtained an effective permeability contour with respect to the wax pattern length and brightness. In addition, we developed a paper-based micromixer of which the mixing ratio was controlled precisely by adjusting the permeability.

Combinational concentration gradient confinement through stagnation flow.

PubMed

Alicia, Toh G G; Yang, Chun; Wang, Zhiping; Nguyen, Nam-Trung

2016-01-21

Concentration gradient generation in microfluidics is typically constrained by two conflicting mass transport requirements: short characteristic times (τ) for precise temporal control of concentration gradients but at the expense of high flow rates and hence, high flow shear stresses (σ). To decouple the limitations from these parameters, here we propose the use of stagnation flows to confine concentration gradients within large velocity gradients that surround the stagnation point. We developed a modified cross-slot (MCS) device capable of feeding binary and combinational concentration sources in stagnation flows. We show that across the velocity well, source-sink pairs can form permanent concentration gradients. As source-sink concentration pairs are continuously supplied to the MCS, a permanently stable concentration gradient can be generated. Tuning the flow rates directly controls the velocity gradients, and hence the stagnation point location, allowing the confined concentration gradient to be focused. In addition, the flow rate ratio within the MCS rapidly controls (τ ∼ 50 ms) the location of the stagnation point and the confined combinational concentration gradients at low flow shear (0.2 Pa < σ < 2.9 Pa). The MCS device described in this study establishes the method for using stagnation flows to rapidly generate and position low shear combinational concentration gradients for shear sensitive biological assays.

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

Britten, J

WET-ETCH FIGURING (WEF) is an automated method of precisely figuring optical materials by the controlled application of aqueous etchant solution. This technology uses surface-tension-gradient-driven flow to confine and stabilize a wetted zone of an etchant solution or other aqueous processing fluid on the surface of an object. This wetted zone can be translated on the surface in a computer-controlled fashion for precise spatial control of the surface reactions occurring (e.g. chemical etching). WEF is particularly suitable for figuring very thin optical materials because it applies no thermal or mechanical stress to the material. Also, because the process is stress-free themore » workpiece can be monitored during figuring using interferometric metrology, and the measurements obtained can be used to control the figuring process in real-time--something that cannot be done with traditional figuring methods.« less

Biology-Inspired Autonomous Control

DTIC Science & Technology

2011-08-31

from load sensing in a turbulent flow field with high levels of plant uncertainty and optical feedback latency. The results of this paper suggest... Mimicry of biological systems, in the form of precise mathematical or physical dynamical modeling, is yielding impressive insight into the underlying...processing and plants , the aerospace industry has been slow to accept adaptive control. In the past decade however, newer methods for design of adaptive

Detecting and Characterizing Semantic Inconsistencies in Ported Code

NASA Technical Reports Server (NTRS)

Ray, Baishakhi; Kim, Miryung; Person, Suzette J.; Rungta, Neha

2013-01-01

Adding similar features and bug fixes often requires porting program patches from reference implementations and adapting them to target implementations. Porting errors may result from faulty adaptations or inconsistent updates. This paper investigates (I) the types of porting errors found in practice, and (2) how to detect and characterize potential porting errors. Analyzing version histories, we define five categories of porting errors, including incorrect control- and data-flow, code redundancy, inconsistent identifier renamings, etc. Leveraging this categorization, we design a static control- and data-dependence analysis technique, SPA, to detect and characterize porting inconsistencies. Our evaluation on code from four open-source projects shows thai SPA can dell-oct porting inconsistencies with 65% to 73% precision and 90% recall, and identify inconsistency types with 58% to 63% precision and 92% to 100% recall. In a comparison with two existing error detection tools, SPA improves precision by 14 to 17 percentage points

Detecting and Characterizing Semantic Inconsistencies in Ported Code

NASA Technical Reports Server (NTRS)

Ray, Baishakhi; Kim, Miryung; Person,Suzette; Rungta, Neha

2013-01-01

Adding similar features and bug fixes often requires porting program patches from reference implementations and adapting them to target implementations. Porting errors may result from faulty adaptations or inconsistent updates. This paper investigates (1) the types of porting errors found in practice, and (2) how to detect and characterize potential porting errors. Analyzing version histories, we define five categories of porting errors, including incorrect control- and data-flow, code redundancy, inconsistent identifier renamings, etc. Leveraging this categorization, we design a static control- and data-dependence analysis technique, SPA, to detect and characterize porting inconsistencies. Our evaluation on code from four open-source projects shows that SPA can detect porting inconsistencies with 65% to 73% precision and 90% recall, and identify inconsistency types with 58% to 63% precision and 92% to 100% recall. In a comparison with two existing error detection tools, SPA improves precision by 14 to 17 percentage points.

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

Alhroob, M.; Boyd, G.; Hasib, A.

Precision ultrasonic measurements in binary gas systems provide continuous real-time monitoring of mixture composition and flow. Using custom micro-controller-based electronics, we have developed an ultrasonic instrument, with numerous potential applications, capable of making continuous high-precision sound velocity measurements. The instrument measures sound transit times along two opposite directions aligned parallel to - or obliquely crossing - the gas flow. The difference between the two measured times yields the gas flow rate while their average gives the sound velocity, which can be compared with a sound velocity vs. molar composition look-up table for the binary mixture at a given temperature andmore » pressure. The look-up table may be generated from prior measurements in known mixtures of the two components, from theoretical calculations, or from a combination of the two. We describe the instrument and its performance within numerous applications in the ATLAS experiment at the CERN Large Hadron Collider (LHC). The instrument can be of interest in other areas where continuous in-situ binary gas analysis and flowmetry are required. (authors)« less

Micro flow-through PCR in a PMMA chip fabricated by KrF excimer laser.

PubMed

Yao, Liying; Liu, Baoan; Chen, Tao; Liu, Shibing; Zuo, Tiechuan

2005-09-01

As the third PCR technology, micro flow-through PCR chip can amplify DNA specifically in an exponential fashion in vitro. Nowadays many academies in the world have successfully amplified DNA using their own-made flow-through PCR chip. In this paper, the ablation principle of PMMA at 248 nm excimer laser was studied, then a PMMA based flow-through PCR chip with 20 cycles was fabricated by excimer laser at 19 kv and 18 mm/min. The chip was bonded together with another cover chip at 105( composite function)C, 160 N and 20 minutes. In the end, it was integrated with electrical thermal thin films and Pt 100 temperature sensors. The temperature controllers was built standard PID digital temperature controller, the temperature control precision was +/- 0.2( composite function)C. The temperature grads between the three temperature zones were 16.5 and 22.2( composite function)C respectively, the gaps between the temperature zones could realize heat insulation.

Gene delivery by direct injection (microinjection) using a controlled-flow system.

PubMed

Dean, David A

2006-12-01

INTRODUCTIONThis protocol describes a method for constant-flow microinjection using the Pneumatic PicoPump (World Precision Instruments). This type of system is very simple and can be assembled on a relatively low budget. In this method, a constant flow of sample is delivered from the tip of the pipette, and the amount of sample injected into the cell is determined by how long the pipette remains in the cell. A typical system is composed of a pressure regulator that can be adjusted for two pressures (back pressure and injection pressure), a capillary holder, and a coarse and fine micromanipulator.

Applications of Sharp Interface Method for Flow Dynamics, Scattering and Control Problems

DTIC Science & Technology

2012-07-30

Reynolds number, Advances in Applied Mathematics and Mechanics, to appear. 17. K. Ito and K. Kunisch, Optimal Control of Parabolic Variational ...provides more precise and detailed sensitivity of the solution and describes the dynamical change due to the variation in the Reynolds number. The immersed... Inequalities , Journal de Math. Pures et Appl, 93 (2010), no. 4, 329-360. 18. K. Ito and K. Kunisch, Semi-smooth Newton Methods for Time-Optimal Control for a

Electro-osmotically driven liquid delivery method and apparatus

DOEpatents

Rakestraw, David J.; Anex, Deon S.; Yan, Chao; Dadoo, Rajeev; Zare, Richard N.

1999-01-01

Method and apparatus for controlling precisely the composition and delivery of liquid at sub-.mu.L/min flow rate. One embodiment of such a delivery system is an electro-osmotically driven gradient flow delivery system that generates dynamic gradient flows with sub-.mu.L/min flow rates by merging a plurality of electro-osmotic flows. These flows are delivered by a plurality of delivery arms attached to a mixing connector, where they mix and then flow into a receiving means, preferably a column. Each inlet of the plurality of delivery arms is placed in a corresponding solution reservoir. A plurality of independent programmable high-voltage power supplies is used to apply a voltage program to each of the plurality of solution reservoirs to regulate the electro-osmotic flow in each delivery arm. The electro-osmotic flow rates in the delivery arms are changed with time according to each voltage program to deliver the required gradient profile to the column.

Upgrade of the gas flow control system of the resistive current leads of the LHC inner triplet magnets: Simulation and experimental validation

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

Perin, A.; Casas-Cubillos, J.; Pezzetti, M.

2014-01-29

The 600 A and 120 A circuits of the inner triplet magnets of the Large Hadron Collider are powered by resistive gas cooled current leads. The current solution for controlling the gas flow of these leads has shown severe operability limitations. In order to allow a more precise and more reliable control of the cooling gas flow, new flowmeters will be installed during the first long shutdown of the LHC. Because of the high level of radiation in the area next to the current leads, the flowmeters will be installed in shielded areas located up to 50 m away frommore » the current leads. The control valves being located next to the current leads, this configuration leads to long piping between the valves and the flowmeters. In order to determine its dynamic behaviour, the proposed system was simulated with a numerical model and validated with experimental measurements performed on a dedicated test bench.« less

Identification of two-phase flow regime based on electrical capacitance tomography and soft-sensing technique

NASA Astrophysics Data System (ADS)

Zhao, Ming-fu; Hu, Xin-Yu; Shao, Yun; Luo, Bin-bin; Wang, Xin

2008-10-01

This article analyses nowadays in common use of football robots in China, intended to improve the football robots' hardware platform system's capability, and designed a football robot which based on DSP core controller, and combined Fuzzy-PID control algorithm. The experiment showed, because of the advantages of DSP, such as quickly operation, various of interfaces, low power dissipation etc. It has great improvement on the football robot's performance of movement, controlling precision, real-time performance.

Laser-assisted chemical vapor deposition setup for fast synthesis of graphene patterns

NASA Astrophysics Data System (ADS)

Zhang, Chentao; Zhang, Jianhuan; Lin, Kun; Huang, Yuanqing

2017-05-01

An automatic setup based on the laser-assisted chemical vapor deposition method has been developed for the rapid synthesis of graphene patterns. The key components of this setup include a laser beam control and focusing unit, a laser spot monitoring unit, and a vacuum and flow control unit. A laser beam with precision control of laser power is focused on the surface of a nickel foil substrate by the laser beam control and focusing unit for localized heating. A rapid heating and cooling process at the localized region is induced by the relative movement between the focalized laser spot and the nickel foil substrate, which causes the decomposing of gaseous hydrocarbon and the out-diffusing of excess carbon atoms to form graphene patterns on the laser scanning path. All the fabrication parameters that affect the quality and number of graphene layers, such as laser power, laser spot size, laser scanning speed, pressure of vacuum chamber, and flow rates of gases, can be precisely controlled and monitored during the preparation of graphene patterns. A simulation of temperature distribution was carried out via the finite element method, providing a scientific guidance for the regulation of temperature distribution during experiments. A multi-layer graphene ribbon with few defects was synthesized to verify its performance of the rapid growth of high-quality graphene patterns. Furthermore, this setup has potential applications in other laser-based graphene synthesis and processing.

Motorization of a surgical microscope for intra-operative navigation and intuitive control.

PubMed

Finke, M; Schweikard, A

2010-09-01

During surgical procedures, various medical systems, e.g. microscope or C-arm, are used. Their precise and repeatable manual positioning can be very cumbersome and interrupts the surgeon's work flow. Robotized systems can assist the surgeon but they require suitable kinematics and control. However, positioning must be fast, flexible and intuitive. We describe a fully motorized surgical microscope. Hardware components as well as implemented applications are specified. The kinematic equations are described and a novel control concept is proposed. Our microscope combines fast manual handling with accurate, automatic positioning. Intuitive control is provided by a small remote control mounted to one of the surgical instruments. Positioning accuracy and repeatability are < 1 mm and vibrations caused by automatic movements fade away in about 1 s. The robotic system assists the surgeon, so that he can position the microscope precisely and repeatedly without interrupting the clinical workflow. The combination of manual und automatic control guarantees fast and flexible positioning during surgical procedures. Copyright 2010 John Wiley & Sons, Ltd.

High precision innovative micropump for artificial pancreas

NASA Astrophysics Data System (ADS)

Chappel, E.; Mefti, S.; Lettieri, G.-L.; Proennecke, S.; Conan, C.

2014-03-01

The concept of artificial pancreas, which comprises an insulin pump, a continuous glucose meter and a control algorithm, is a major step forward in managing patient with type 1 diabetes mellitus. The stability of the control algorithm is based on short-term precision micropump to deliver rapid-acting insulin and to specific integrated sensors able to monitor any failure leading to a loss of accuracy. Debiotech's MEMS micropump, based on the membrane pump principle, is made of a stack of 3 silicon wafers. The pumping chamber comprises a pillar check-valve at the inlet, a pumping membrane which is actuated against stop limiters by a piezo cantilever, an anti-free-flow outlet valve and a pressure sensor. The micropump inlet is tightly connected to the insulin reservoir while the outlet is in direct communication with the patient skin via a cannula. To meet the requirement of a pump dedicated to closed-loop application for diabetes care, in addition to the well-controlled displacement of the pumping membrane, the high precision of the micropump is based on specific actuation profiles that balance effect of pump elasticity in low-consumption push-pull mode.

Three-dimensional microbubble streaming flows

NASA Astrophysics Data System (ADS)

Rallabandi, Bhargav; Marin, Alvaro; Rossi, Massimiliano; Kaehler, Christian; Hilgenfeldt, Sascha

2014-11-01

Streaming due to acoustically excited bubbles has been used successfully for applications such as size-sorting, trapping and focusing of particles, as well as fluid mixing. Many of these applications involve the precise control of particle trajectories, typically achieved using cylindrical bubbles, which establish planar flows. Using astigmatic particle tracking velocimetry (APTV), we show that, while this two-dimensional picture is a useful description of the flow over short times, a systematic three-dimensional flow structure is evident over long time scales. We demonstrate that this long-time three-dimensional fluid motion can be understood through asymptotic theory, superimposing secondary axial flows (induced by boundary conditions at the device walls) onto the two-dimensional description. This leads to a general framework that describes three-dimensional flows in confined microstreaming systems, guiding the design of applications that profit from minimizing or maximizing these effects.

Development of a radiative heating facility for studying flow and heat transfer in hydrocarbon-cooled structures

NASA Astrophysics Data System (ADS)

Dong, Da; Lu, Yang; Yuan, Yueming; Fan, Xuejun

2018-06-01

An experimental facility was designed to simulate the heat exchange between the hot gas and the fuel-cooled wall in a scramjet combustor. Thermal radiation from an electrically heated graphite plate is employed to unilaterally heat up a multi-channeled cooling plate. A maximum heat flux of over 0.8 MW/m2 was achieved for an effective heating area up to 1000 mm × 40 mm. Precise control of the back pressure of a coolant (up to 5 MPa) in a unique way was also demonstrated. With this facility, studies of flow and heat transfer in hydrocarbon-cooled structures can be performed under a well-controlled manner.

In-plane cost-effective magnetically actuated valve for microfluidic applications

NASA Astrophysics Data System (ADS)

Pugliese, Marco; Ferrara, Francesco; Bramanti, Alessandro Paolo; Gigli, Giuseppe; Maiorano, Vincenzo

2017-04-01

We present a new in-plane magnetically actuated microfluidic valve. Its simple design includes a circular area joining two channels lying on the same plane. The area is parted by a septum lying on and adhering to a magneto-active polymeric ‘floor’ membrane, keeping the channels normally separated (valve closed). Under the action of a magnetic field, the membrane collapses, letting the liquid flow below the septum (valve open). The valve was extensively characterized experimentally, and modeled and optimized theoretically. The growing interest in lab on chips, especially for diagnostics and precision medicine, is driving researchers towards smart, efficient and low cost solutions to the management of biological samples. In this context, the valve developed in this work represents a useful building-block for microfluidic applications requiring precise flow control, its main features being easy and rapid manufacturing, biocompatibility and low cost.

Optimization and Control of Acoustic Liner Impedance with Bias Flow

NASA Technical Reports Server (NTRS)

Wood, Houston; Follet, Jesse

2000-01-01

Because communities are impacted by steady increases in aircraft traffic, aircraft noise continues to be a growing problem for the growth of commercial aviation. Research has focused on improving the design of specific high noise source areas of aircraft and on noise control measures to alleviate noise radiated from aircraft to the surrounding environment. Engine duct liners have long been a principal means of attenuating engine noise. The ability to control in-situ the acoustic impedance of a liner would provide a valuable tool to improve the performance of liners. The acoustic impedance of a liner is directly related to the sound absorption qualities of that liner. Increased attenuation rates, the ability to change liner acoustic impedance to match various operating conditions, or the ability to tune a liner to more precisely match design impedance represent some ways that in-situ impedance control could be useful. With this in mind, the research to be investigated will focus on improvements in the ability to control liner impedance using a mean flow through the liner which is referred to as bias flow.

Low-noise humidity controller for imaging water mediated processes in atomic force microscopy

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

Gaponenko, I., E-mail: iaroslav.gaponenko@unige.ch; Gamperle, L.; Herberg, K.

2016-06-15

We demonstrate the construction of a novel low-noise continuous flow humidity controller and its integration with a commercial variable-temperature atomic force microscope fluid cell, allowing precise control of humidity and temperature at the sample during nanoscale measurements. Based on wet and dry gas mixing, the design allows a high mechanical stability to be achieved by means of an ultrasonic atomiser for the generation of water-saturated gas, improving upon previous bubbler-based architectures. Water content in the flow is measured both at the inflow and outflow of the fluid cell, enabling the monitoring of water condensation and icing, and allowing controlled variationmore » of the sample temperature independently of the humidity. To benchmark the performance of the controller, the results of detailed noise studies and time-based imaging of the formation of ice layers on highly oriented pyrolytic graphite are shown.« less

Flow-induced fiber deformation in a confined microchannel: in situ mechanical testing of gels

NASA Astrophysics Data System (ADS)

Duprat, Camille; Berthet, Helene; Wexler, Jason; Du Roure, Olivia; Lindner, Anke

2014-11-01

Photopolymerized hydrogels are a functional template for micro-particle fabrication, microflowsensors and microbiology experiments. The control and knowledge of their mechanical properties are paramount to many applications. We have designed a novel robust method to determine these properties. We measure the deformation of a gel beam of precisely controlled shape, under a controlled flow forcing, which provides a direct measurement of the Young's modulus of the gel upon its fabrication. We then use this method to determine the mechanical properties of the commonly used poly(ethylene glycol) diacrylate (PEGDA) under various experimental conditions. The mechanical properties of the gel can be highly tuned, yielding two orders of magnitude in the Young's modulus. We provide a simple control parameter, the UV exposure time, to have a great control over the network properties, and rationalize these observations by studying the kinetics of the polymerization reaction.

The use of temperature programmable flow tubes for the study of atmospheric aerosols

NASA Astrophysics Data System (ADS)

Khalizov, A.; Sloan, J. J.

2003-04-01

In order to understand the response of atmospheric aerosols to changes they encounter in the natural atmosphere, it is usually necessary to observe models of these aerosol systems under carefully controlled laboratory conditions. This is particularly difficult for the condensed phase, for which agglomeration, gas-particle exchange and gravitational settling affect the composition and limit the observation time. Traditionally, studies of this kind have been carried out in large static chambers and flow tubes. While large chambers provide relatively long observations times, they afford the experimenter less direct control over the environment of the particles. Flow tubes, on the other hand provide very precise control of the experimental conditions, but a much shorter contact time. We have used temperature programmable flow tubes for the past decade to study the composition, size and phase changes that occur when aerosols are exposed to variations in the temperature and composition of the surrounding atmosphere. In many cases, our measurements also yield accurate rate constants for the nucleation of solids in liquid droplets. In this presentation, we will illustrate the capabilities of this method using results obtained from a new temperature programmable flow tube recently built in our laboratory.

"Off-the-shelf" 3-D microfluidic nozzle.

PubMed

Terray, Alex; Hart, Sean J

2010-07-07

We present the construction and operation of a microfluidic nozzle created using several standard fluidic parts available commercially. By elegantly combining several pieces from a standard assembly, a capillary and a few other standard parts, we were able to develop a novel device. Using this device, precise axisymmetric flow focusing of particles was achieved and observed at the exit of the nozzle and within a connected microfluidic device several centimetres away. Sheath and core flow rates were varied to show influence and control over the width of the focused particles.

Compact and Integrated Liquid Bismuth Propellant Feed System

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Stanojev, Boris; Korman, Valentin; Gross, Jeffrey T.

2007-01-01

Operation of Hall thrusters with bismuth propellant has been shown to be a promising path toward high-power, high-performance, long-lifetime electric propulsion for spaceflight missions [1]. There has been considerable effort in the past three years aimed at resuscitating this promising technology and validating earlier experimental results indicating the advantages of a bismuth-fed Hall thruster. A critical element of the present effort is the precise metering of propellant to the thruster, since performance cannot be accurately assessed without an accurate accounting of mass flow rate. Earlier work used a pre./post-test propellant weighing scheme that did not provide any real-time measurement of mass flow rate while the thruster was firing, and makes subsequent performance calculations difficult. The motivation of the present work is to develop a precision liquid bismuth Propellant Management System (PMS) that provides hot, molten bismuth to the thruster while simultaneously monitoring in real-time the propellant mass flow rate. The system is a derivative of our previous propellant feed system [2], but the present system represents a more compact design. In addition, all control electronics are integrated into a single unit and designed to reside on a thrust stand and operate in the relevant vacuum environment where the thruster is operating, significantly increasing the present technology readiness level of liquid metal propellant feed systems. The design of various critical components in a bismuth PMS are described. These include the bismuth reservoir and pressurization system, 'hotspot' flow sensor, power system and integrated control system. Particular emphasis is given to selection of the electronics employed in this system and the methods that were used to isolate the power and control systems from the high-temperature portions of the feed system and thruster. Open loop calibration test results from the 'hotspot' flow sensor are reported, and results of integrated thruster/PMS tests demonstrate operation of the feed system in the relevant environment.

Fabrication and Operation of Microfluidic Hanging-Drop Networks.

PubMed

Misun, Patrick M; Birchler, Axel K; Lang, Moritz; Hierlemann, Andreas; Frey, Olivier

2018-01-01

The hanging-drop network (HDN) is a technology platform based on a completely open microfluidic network at the bottom of an inverted, surface-patterned substrate. The platform is predominantly used for the formation, culturing, and interaction of self-assembled spherical microtissues (spheroids) under precisely controlled flow conditions. Here, we describe design, fabrication, and operation of microfluidic hanging-drop networks.

Effect of cleaning status on accuracy and precision of oxygen flowmeters of various ages.

PubMed

Fissekis, Stephanie; Hodgson, David S; Bello, Nora M

2017-07-01

To evaluate oxygen flowmeters for accuracy and precision, assess the effects of cleaning and assess conformity to the American Society for Testing Materials (ASTM) standards. Experimental study. The flow of oxygen flowmeters from 31 anesthesia machines aged 1-45 years was measured before and after cleaning using a volumetric flow analyzer set at 0.5, 1.0, 2.0, 3.0, and 4.0 L minute -1 . A general linear mixed models approach was used to assess flow accuracy and precision. Flowmeters 1 year of age delivered accurate mean oxygen flows at all settings regardless of cleaning status. Flowmeters ≥5 years of age underdelivered at flows of 3.0 and 4.0 L minute -1 . Flowmeters ≥12 years underdelivered at flows of 2.0, 3.0 and 4.0 L minute -1 prior to cleaning. There was no evidence of any beneficial effect of cleaning on accuracy of flowmeters 5-12 years of age (p > 0.22), but the accuracy of flowmeters ≥15 years of age was improved by cleaning (p < 0.05). Regardless of age, cleaning increased precision, decreasing flow variability by approximately 17%. Nine of 31 uncleaned flowmeters did not meet ASTM standards. After cleaning, a different set of nine flowmeters did not meet standards, including three that had met standards prior to cleaning. Older flowmeters were more likely to underdeliver oxygen, especially at higher flows. Regardless of age, cleaning decreased flow variability, improving precision. However, flowmeters still may fail to meet ASTM standards, regardless of cleaning status. Cleaning anesthesia machine oxygen flowmeters improved precision for all tested machines and partially corrected inaccuracies in flowmeters ≥15 years old. A notable proportion of flowmeters did not meet ASTM standards. Cleaning did not ensure that they subsequently conformed to ASTM standards. We recommend annual flow output validation to identify whether flowmeters are acceptable for continued clinical use. Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

Electro-osmotically driven liquid delivery method and apparatus

DOEpatents

Rakestraw, D.J.; Anex, D.S.; Yan, C.; Dadoo, R.; Zare, R.N.

1999-08-24

Method and apparatus are disclosed for controlling precisely the composition and delivery of liquid at sub-{micro}L/min flow rate. One embodiment of such a delivery system is an electro-osmotically driven gradient flow delivery system that generates dynamic gradient flows with sub-{micro}L/min flow rates by merging a plurality of electro-osmotic flows. These flows are delivered by a plurality of delivery arms attached to a mixing connector, where they mix and then flow into a receiving means, preferably a column. Each inlet of the plurality of delivery arms is placed in a corresponding solution reservoir. A plurality of independent programmable high-voltage power supplies is used to apply a voltage program to each of the plurality of solution reservoirs to regulate the electro-osmotic flow in each delivery arm. The electro-osmotic flow rates in the delivery arms are changed with time according to each voltage program to deliver the required gradient profile to the column. 4 figs.

Improved sulfide mitigation in sewers through on-line control of ferrous salt dosing.

PubMed

Ganigué, Ramon; Jiang, Guangming; Liu, Yiqi; Sharma, Keshab; Wang, Yue-Cong; Gonzalez, José; Nguyen, Tung; Yuan, Zhiguo

2018-05-15

Water utilities worldwide spend annually billions of dollars to control sulfide-induced corrosion in sewers. Iron salts chemically oxidize and/or precipitate dissolved sulfide in sewage and are especially used in medium- and large-size sewers. Iron salt dosing rates are defined ad hoc, ignoring variation in sewage flows and sulfide levels. This often results in iron overdosing or poor sulfide control. Online dosing control can adjust the chemical dosing rates to current (and future) state of the sewer system, allowing high-precision, stable and cost-effective sulfide control. In this paper, we report a novel and robust online control strategy for the dosing of ferrous salt in sewers. The control considers the fluctuation of sewage flow, pH, sulfide levels and also the perturbation from rainfall. Sulfide production in the pipe is predicted using auto-regressive models (AR) based on current flow measurements, which in turn can be used to determine the dose of ferrous salt required for cost-effective sulfide control. Following comprehensive model-based assesment, the control was successfully validated and its effectiveness demonstrated in a 3-week field trial. The online control algorithm controlled sulfide below the target level (0.5 mg S/L) while reducing chemical dosing up to 30%. Copyright © 2018 Elsevier Ltd. All rights reserved.

An Experimental Approach to Controllably Vary Protein Oxidation While Minimizing Electrode Adsorption for Boron-Doped Diamond Electrochemical Surface Mapping Applications

PubMed Central

McClintock, Carlee S; Hettich, Robert L.

2012-01-01

Oxidative protein surface mapping has become a powerful approach for measuring the solvent accessibility of folded protein structures. A variety of techniques exist for generating the key reagent – hydroxyl radicals – for these measurements; however, these approaches range significantly in their complexity and expense of operation. This research expands upon earlier work to enhance the controllability of boron-doped diamond (BDD) electrochemistry as an easily accessible tool for producing hydroxyl radicals in order to oxidize a range of intact proteins. Efforts to modulate oxidation level while minimizing the adsorption of protein to the electrode involved the use of relatively high flow rates to reduce protein residence time inside the electrochemical flow chamber. Additionally, a different cell activation approach using variable voltage to supply a controlled current allowed us to precisely tune the extent of oxidation in a protein-dependent manner. In order to gain perspective on the level of protein adsorption onto the electrode surface, studies were conducted to monitor protein concentration during electrolysis and gauge changes in the electrode surface between cell activation events. This report demonstrates the successful use of BDD electrochemistry for greater precision in generating a target number of oxidation events upon intact proteins. PMID:23210708

Automated single cell microbioreactor for monitoring intracellular dynamics and cell growth in free solution†

PubMed Central

Johnson-Chavarria, Eric M.; Agrawal, Utsav; Tanyeri, Melikhan; Kuhlman, Thomas E.

2014-01-01

We report an automated microfluidic-based platform for single cell analysis that allows for cell culture in free solution with the ability to control the cell growth environment. Using this approach, cells are confined by the sole action of gentle fluid flow, thereby enabling non-perturbative analysis of cell growth away from solid boundaries. In addition, the single cell microbioreactor allows for precise and time-dependent control over cell culture media, with the combined ability to observe the dynamics of non-adherent cells over long time scales. As a proof-of-principle demonstration, we used the platform to observe dynamic cell growth, gene expression, and intracellular diffusion of repressor proteins while precisely tuning the cell growth environment. Overall, this microfluidic approach enables the direct observation of cellular dynamics with exquisite control over environmental conditions, which will be useful for quantifying the behaviour of single cells in well-defined media. PMID:24836754

Development of a low-cost mini environment chamber for precision instruments

NASA Astrophysics Data System (ADS)

Feng, Jian; Li, Rui-Jun; He, Ya-Xiong; Fan, Kuang-Chao

2016-01-01

The wavelength of laser interferometer used widely in precision measurement instrument is affected by the refractive index of surrounding air, which depends on the temperature, relative humidity (RH) and air pressure. A low-cost mini chamber based on the natural convection principle with high-precision temperature-controlled and humidity-suppressed is proposed in this paper. The main chamber is built up by acrylic walls supported by aluminum beam column and are tailored according to the required space. A thin layer of vacuum insulation panel (VIP) with an ultralow thermal conductivity coefficient is adhered around the walls so as to prevent heat exchange with room air. A high-precision temperature sensor measuring the temperature near the instrument's measuring point provides a feedback signal to a proportional-integral-derivative (PID) controller. Several thermoelectric coolers uniformly arranged on the ceiling of the chamber to cool the air inside the chamber directly without any air supply system, yielding a vibration-free cooling system. A programmable power supply is used as the driver for the coolers to generate different cooling capacities. The down-flowing cool air and the up-flowing hot air form a natural convection, and the air temperature in the chamber gradually becomes stable and finally reaches the temperature set by the PID controller. Recycled desiccant contained silica gels that have high affinity for water is used as a drying agent. Experimental results show that in about two hours the system's steady state error is 0.003°C on average, and the variation range is less than ± 0.02°C when the set temperature is 20°C, the RH is reduced from 66% to about 48%. This innovative mini chamber has the advantages of low-cost, vibration-free, and low energy-consumption. It can be used for any micro/nanomeasurement instrument and its volume can be customer-designed.

Active Control of Unsteady Gasdynamics for Shock Compression and Turbulence Generation

DTIC Science & Technology

2012-09-13

lens has a specified register, which is the distance from the mounting ring to the focal point of the lens. This value is extremely precise and must be...J., “Air Flow Modulation for Refined Control of the Combustion Dynamics Using a Novel Actuator,” Journal of Engineering for Gas Turbines and Power...Cycle (RBCC) system; if done with a turbine engine, a Turbine -Based Combined Cycle (TBCC) system. However, carrying two entire propulsion systems

Zero Boil-Off Tank (ZBOT) Experiment

NASA Technical Reports Server (NTRS)

Mcquillen, John

2016-01-01

The Zero-Boil-Off Tank (ZBOT) experiment has been developed as a small scale ISS experiment aimed at delineating important fluid flow, heat and mass transport, and phase change phenomena that affect cryogenic storage tank pressurization and pressure control in microgravity. The experiments use a simulant transparent low boiling point fluid (PnP) in a sealed transparent Dewar to study and quantify: (a) fluid flow and thermal stratification during pressurization; (b) mixing, thermal destratification, depressurization, and jet-ullage penetration during pressure control by jet mixing. The experiment will provide valuable microgravity empirical two-phase data associated with the above-mentioned physical phenomena through highly accurate local wall and fluid temperature and pressure measurements, full-field phase-distribution and flow visualization. Moreover, the experiments are performed under tightly controlled and definable heat transfer boundary conditions to provide reliable high-fidelity data and precise input as required for validation verification of state-of-the-art two-phase CFD models developed as part of this research and by other groups in the international scientific and cryogenic fluid management communities.

Doppler flowmeter

DOEpatents

Karplus, H.H.B.; Raptis, A.C.

1981-11-13

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

Doppler flowmeter

DOEpatents

Karplus, Henry H. B.; Raptis, Apostolos C.

1983-01-01

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

Droplets Formation and Merging in Two-Phase Flow Microfluidics

PubMed Central

Gu, Hao; Duits, Michel H. G.; Mugele, Frieder

2011-01-01

Two-phase flow microfluidics is emerging as a popular technology for a wide range of applications involving high throughput such as encapsulation, chemical synthesis and biochemical assays. Within this platform, the formation and merging of droplets inside an immiscible carrier fluid are two key procedures: (i) the emulsification step should lead to a very well controlled drop size (distribution); and (ii) the use of droplet as micro-reactors requires a reliable merging. A novel trend within this field is the use of additional active means of control besides the commonly used hydrodynamic manipulation. Electric fields are especially suitable for this, due to quantitative control over the amplitude and time dependence of the signals, and the flexibility in designing micro-electrode geometries. With this, the formation and merging of droplets can be achieved on-demand and with high precision. In this review on two-phase flow microfluidics, particular emphasis is given on these aspects. Also recent innovations in microfabrication technologies used for this purpose will be discussed. PMID:21731459

An integrated laser trap/flow control video microscope for the study of single biomolecules.

PubMed Central

Wuite, G J; Davenport, R J; Rappaport, A; Bustamante, C

2000-01-01

We have developed an integrated laser trap/flow control video microscope for mechanical manipulation of single biopolymers. The instrument is automated to maximize experimental throughput. A single-beam optical trap capable of trapping micron-scale polystyrene beads in the middle of a 200-microm-deep microchamber is used, making it possible to insert a micropipette inside this chamber to hold a second bead by suction. Together, these beads function as easily exchangeable surfaces between which macromolecules of interest can be attached. A computer-controlled flow system is used to exchange the liquid in the chamber and to establish a flow rate with high precision. The flow and the optical trap can be used to exert forces on the beads, the displacements of which can be measured either by video microscopy or by laser deflection. To test the performance of this instrument, individual biotinylated DNA molecules were assembled between two streptavidin beads, and the DNA elasticity was characterized using both laser trap and flow forces. DNA extension under varying forces was measured by video microscopy. The combination of the flow system and video microscopy is a versatile design that is particularly useful for the study of systems susceptible to laser-induced damage. This capability was demonstrated by following the translocation of transcribing RNA polymerase up to 650 s. PMID:10920045

Advances in colloidal manipulation and transport via hydrodynamic interactions.

PubMed

Martínez-Pedrero, F; Tierno, P

2018-06-01

In this review article, we highlight many recent advances in the field of micromanipulation of colloidal particles using hydrodynamic interactions (HIs), namely solvent mediated long-range interactions. At the micrsocale, the hydrodynamic laws are time reversible and the flow becomes laminar, features that allow precise manipulation and control of colloidal matter. We focus on different strategies where externally operated microstructures generate local flow fields that induce the advection and motion of the surrounding components. In addition, we review cases where the induced flow gives rise to hydrodynamic bound states that may synchronize during the process, a phenomenon essential in different systems such as those that exhibit self-assembly and swarming. Copyright © 2018 Elsevier Inc. All rights reserved.

A self-adaptive-grid method with application to airfoil flow

NASA Technical Reports Server (NTRS)

Nakahashi, K.; Deiwert, G. S.

1985-01-01

A self-adaptive-grid method is described that is suitable for multidimensional steady and unsteady computations. Based on variational principles, a spring analogy is used to redistribute grid points in an optimal sense to reduce the overall solution error. User-specified parameters, denoting both maximum and minimum permissible grid spacings, are used to define the all-important constants, thereby minimizing the empiricism and making the method self-adaptive. Operator splitting and one-sided controls for orthogonality and smoothness are used to make the method practical, robust, and efficient. Examples are included for both steady and unsteady viscous flow computations about airfoils in two dimensions, as well as for a steady inviscid flow computation and a one-dimensional case. These examples illustrate the precise control the user has with the self-adaptive method and demonstrate a significant improvement in accuracy and quality of the solutions.

Screw-actuated displacement micropumps for thermoplastic microfluidics.

PubMed

Han, J Y; Rahmanian, O D; Kendall, E L; Fleming, N; DeVoe, D L

2016-10-05

The fabrication of on-chip displacement pumps integrated into thermoplastic chips is explored as a simple and low cost method for achieving precise and programmable flow control for disposable microfluidic systems. The displacement pumps consist of stainless steel screws inserted into threaded ports machined into a thermoplastic substrate which also serve as on-chip reagent storage reservoirs. Three different methods for pump sealing are investigated to enable high pressure flows without leakage, and software-defined control of multiple pumps is demonstrated in a self-contained platform using a compact and self-contained microcontroller for operation. Using this system, flow rates ranging from 0.5-40 μl min -1 are demonstrated. The pumps are combined with on-chip burst valves to fully seal multiple reagents into fabricated chips while providing on-demand fluid distribution in a downstream microfluidic network, and demonstrated for the generation of size-tunable water-in-oil emulsions.

Automatic Control by Microprocessor of a Patient's Weight Loss During an Extrarenal Purification Session by Hemofiltration

PubMed Central

Faucheux, F.; L'Huillier, J.P.; Rouillion, P.; Yvroud, E.; Kessler, M.; Huriet, C.

1982-01-01

The extranephric cleaning by means of hemofiltration and generally operations in extracorporal circulation requires the blood derivation towards a treatment apparatus: filtration by means of hemodialysis, oxygenation. The working principle of the treatment apparatuses does not simply allow to connect the blood flow taken from the patient. A control of the patient is therefore necessary to have a treatment performed in good conditions. The method that we propose consists in weighting the variable containing unit of the apparatus and in subjecting this weight to a value determined by the physician. This value is programmed on the machine before the treatment session. The control is performed by means of an action on the differential flow and allow a precise control of the weight loss of the patient during a treatment in extranephric cleaning by means of hemofiltration.

Shape-Controlled Synthesis of Hybrid Nanomaterials via Three-Dimensional Hydrodynamic Focusing

PubMed Central

2015-01-01

Shape-controlled synthesis of nanomaterials through a simple, continuous, and low-cost method is essential to nanomaterials research toward practical applications. Hydrodynamic focusing, with its advantages of simplicity, low-cost, and precise control over reaction conditions, has been used for nanomaterial synthesis. While most studies have focused on improving the uniformity and size control, few have addressed the potential of tuning the shape of the synthesized nanomaterials. Here we demonstrate a facile method to synthesize hybrid materials by three-dimensional hydrodynamic focusing (3D-HF). While keeping the flow rates of the reagents constant and changing only the flow rate of the buffer solution, the molar ratio of two reactants (i.e., tetrathiafulvalene (TTF) and HAuCl4) within the reaction zone varies. The synthesized TTF–Au hybrid materials possess very different and predictable morphologies. The reaction conditions at different buffer flow rates are studied through computational simulation, and the formation mechanisms of different structures are discussed. This simple one-step method to achieve continuous shape-tunable synthesis highlights the potential of 3D-HF in nanomaterials research. PMID:25268035

Shape-controlled synthesis of hybrid nanomaterials via three-dimensional hydrodynamic focusing.

PubMed

Lu, Mengqian; Yang, Shikuan; Ho, Yi-Ping; Grigsby, Christopher L; Leong, Kam W; Huang, Tony Jun

2014-10-28

Shape-controlled synthesis of nanomaterials through a simple, continuous, and low-cost method is essential to nanomaterials research toward practical applications. Hydrodynamic focusing, with its advantages of simplicity, low-cost, and precise control over reaction conditions, has been used for nanomaterial synthesis. While most studies have focused on improving the uniformity and size control, few have addressed the potential of tuning the shape of the synthesized nanomaterials. Here we demonstrate a facile method to synthesize hybrid materials by three-dimensional hydrodynamic focusing (3D-HF). While keeping the flow rates of the reagents constant and changing only the flow rate of the buffer solution, the molar ratio of two reactants (i.e., tetrathiafulvalene (TTF) and HAuCl4) within the reaction zone varies. The synthesized TTF-Au hybrid materials possess very different and predictable morphologies. The reaction conditions at different buffer flow rates are studied through computational simulation, and the formation mechanisms of different structures are discussed. This simple one-step method to achieve continuous shape-tunable synthesis highlights the potential of 3D-HF in nanomaterials research.

Algorithm of dynamic regulation of a system of duct, for a high accuracy climatic system

NASA Astrophysics Data System (ADS)

Arbatskiy, A. A.; Afonina, G. N.; Glazov, V. S.

2017-11-01

Currently, major part of climatic system, are stationary in projected mode only. At the same time, many modern industrial sites, require constant or periodical changes in technological process. That is 80% of the time, the industrial site is not require ventilation system in projected mode and high precision of climatic parameters must maintain. While that not constantly is in use for climatic systems, which use in parallel for different rooms, we will be have a problem for balance of duct system. For this problem, was created the algorithm for quantity regulation, with minimal changes. Dynamic duct system: Developed of parallel control system of air balance, with high precision of climatic parameters. The Algorithm provide a permanent pressure in main duct, in different a flow of air. Therefore, the ending devises air flow have only one parameter for regulation - flaps open area. Precision of regulation increase and the climatic system provide high precision for temperature and humidity (0,5C for temperature, 5% for relative humidity). Result: The research has been made in CFD-system - PHOENICS. Results for velocity of air in duct, for pressure of air in duct for different operation mode, has been obtained. Equation for air valves positions, with different parameters for climate in room’s, has been obtained. Energy saving potential for dynamic duct system, for different types of a rooms, has been calculated.

Functional importance of blood flow dynamics and partial oxygen pressure in the anterior pituitary.

PubMed

Schaeffer, Marie; Hodson, David J; Lafont, Chrystel; Mollard, Patrice

2010-12-01

The pulsatile release of hormone is obligatory for the control of a range of important body homeostatic functions. To generate these pulses, endocrine organs have developed finely regulated mechanisms to modulate blood flow both to meet the metabolic demand associated with intense endocrine cell activity and to ensure the temporally precise uptake of secreted hormone into the bloodstream. With a particular focus on the pituitary gland as a model system, we review here the importance of the interplay between blood flow regulation and oxygen tensions in the functioning of endocrine systems, and the known regulatory signals involved in the modification of flow patterns under both normal physiological and pathological conditions. © 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes

NASA Astrophysics Data System (ADS)

Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

2015-12-01

Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.

A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes.

PubMed

Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

2015-12-01

Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well.

Magnetic Control of Lateral Migration of Ellipsoidal Microparticles in Microscale Flows

NASA Astrophysics Data System (ADS)

Zhou, Ran; Sobecki, Christopher A.; Zhang, Jie; Zhang, Yanzhi; Wang, Cheng

2017-08-01

Precise manipulations of nonspherical microparticles by shape have diverse applications in biology and biomedical engineering. Here, we study lateral migration of ellipsoidal paramagnetic microparticles in low-Reynolds-number flows under uniform magnetic fields. We show that magnetically induced torque alters the rotation dynamics of the particle and results in shape-dependent lateral migration. By adjusting the direction of the magnetic field, we demonstrate versatile control of the symmetric and asymmetric rotation of the particles, thereby controlling the direction of the particle's lateral migration. The particle rotations are experimentally measured, and their symmetry or asymmetry characteristics agree well with the prediction from a simple theory. The lateral migration mechanism is found to be valid for nonmagnetic particles suspended in a ferrofluid. Finally, we demonstrate shape-based sorting of microparticles by exploiting the proposed migration mechanism.

Synthetic Capillaries to Control Microscopic Blood Flow.

PubMed

Sarveswaran, K; Kurz, V; Dong, Z; Tanaka, T; Penny, S; Timp, G

2016-02-24

Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using "live cell lithography"(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision-no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100-1000 cells, organized hierarchically to express a predictable function.

Parallel Estimation and Control Architectures for Deep-Space Formation Flying Spacecraft

NASA Technical Reports Server (NTRS)

Hadaegh, Fred Y.; Smith, Roy S.

2006-01-01

The formation flying of precisely controlled spacecraft in deep space can be used to implement optical instruments capable of imaging planets in other solar systems. The distance of the formation from Earth necessitates a significant level of autonomy and each spacecraft must base its actions on its estimates of the location and velocity of the other spacecraft. Precise coordination and control is the key requirement in such missions and the flow of information between spacecraft must be carefully designed. Doing this in an efficient and optimal manner requires novel techniques for the design of the on-board estimators. The use of standard Kalman filter-based designs can lead to unanticipated dynamics--which we refer to as disagreement dynamics--in the estimators' errors. We show how communication amongst the spacecraft can be designed in order to control all of the dynamics within the formation. We present several results relating the topology of the communication network to the resulting closed-loop control dynamics of the formation. The consequences for the design of the control, communication and coordination are discussed.

Arrival Metering Precision Study

NASA Technical Reports Server (NTRS)

Prevot, Thomas; Mercer, Joey; Homola, Jeffrey; Hunt, Sarah; Gomez, Ashley; Bienert, Nancy; Omar, Faisal; Kraut, Joshua; Brasil, Connie; Wu, Minghong, G.

2015-01-01

This paper describes the background, method and results of the Arrival Metering Precision Study (AMPS) conducted in the Airspace Operations Laboratory at NASA Ames Research Center in May 2014. The simulation study measured delivery accuracy, flight efficiency, controller workload, and acceptability of time-based metering operations to a meter fix at the terminal area boundary for different resolution levels of metering delay times displayed to the air traffic controllers and different levels of airspeed information made available to the Time-Based Flow Management (TBFM) system computing the delay. The results show that the resolution of the delay countdown timer (DCT) on the controllers display has a significant impact on the delivery accuracy at the meter fix. Using the 10 seconds rounded and 1 minute rounded DCT resolutions resulted in more accurate delivery than 1 minute truncated and were preferred by the controllers. Using the speeds the controllers entered into the fourth line of the data tag to update the delay computation in TBFM in high and low altitude sectors increased air traffic control efficiency and reduced fuel burn for arriving aircraft during time based metering.

Effective Light Directed Assembly of Building Blocks with Microscale Control.

PubMed

Dinh, Ngoc-Duy; Luo, Rongcong; Christine, Maria Tankeh Asuncion; Lin, Weikang Nicholas; Shih, Wei-Chuan; Goh, James Cho-Hong; Chen, Chia-Hung

2017-06-01

Light-directed forces have been widely used to pattern micro/nanoscale objects with precise control, forming functional assemblies. However, a substantial laser intensity is required to generate sufficient optical gradient forces to move a small object in a certain direction, causing limited throughput for applications. A high-throughput light-directed assembly is demonstrated as a printing technology by introducing gold nanorods to induce thermal convection flows that move microparticles (diameter = 40 µm to several hundreds of micrometers) to specific light-guided locations, forming desired patterns. With the advantage of effective light-directed assembly, the microfluidic-fabricated monodispersed biocompatible microparticles are used as building blocks to construct a structured assembly (≈10 cm scale) in ≈2 min. The control with microscale precision is approached by changing the size of the laser light spot. After crosslinking assembly of building blocks, a novel soft material with wanted pattern is approached. To demonstrate its application, the mesenchymal stem-cell-seeded hydrogel microparticles are prepared as functional building blocks to construct scaffold-free tissues with desired structures. This light-directed fabrication method can be applied to integrate different building units, enabling the bottom-up formation of materials with precise control over their internal structure for bioprinting, tissue engineering, and advanced manufacturing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care.

PubMed

Ciaffoni, Luca; O'Neill, David P; Couper, John H; Ritchie, Grant A D; Hancock, Gus; Robbins, Peter A

2016-08-01

There are no satisfactory methods for monitoring oxygen consumption in critical care. To address this, we adapted laser absorption spectroscopy to provide measurements of O2, CO2, and water vapor within the airway every 10 ms. The analyzer is integrated within a novel respiratory flow meter that is an order of magnitude more precise than other flow meters. Such precision, coupled with the accurate alignment of gas concentrations with respiratory flow, makes possible the determination of O2 consumption by direct integration over time of the product of O2 concentration and flow. The precision is illustrated by integrating the balance gas (N2 plus Ar) flow and showing that this exchange was near zero. Measured O2 consumption changed by <5% between air and O2 breathing. Clinical capability was illustrated by recording O2 consumption during an aortic aneurysm repair. This device now makes easy, accurate, and noninvasive measurement of O2 consumption for intubated patients in critical care possible.

In-airway molecular flow sensing: A new technology for continuous, noninvasive monitoring of oxygen consumption in critical care

PubMed Central

Ciaffoni, Luca; O’Neill, David P.; Couper, John H.; Ritchie, Grant A. D.; Hancock, Gus; Robbins, Peter A.

2016-01-01

There are no satisfactory methods for monitoring oxygen consumption in critical care. To address this, we adapted laser absorption spectroscopy to provide measurements of O2, CO2, and water vapor within the airway every 10 ms. The analyzer is integrated within a novel respiratory flow meter that is an order of magnitude more precise than other flow meters. Such precision, coupled with the accurate alignment of gas concentrations with respiratory flow, makes possible the determination of O2 consumption by direct integration over time of the product of O2 concentration and flow. The precision is illustrated by integrating the balance gas (N2 plus Ar) flow and showing that this exchange was near zero. Measured O2 consumption changed by <5% between air and O2 breathing. Clinical capability was illustrated by recording O2 consumption during an aortic aneurysm repair. This device now makes easy, accurate, and noninvasive measurement of O2 consumption for intubated patients in critical care possible. PMID:27532048

Development of a split-flow system for high precision variable sample introduction in supercritical fluid chromatography.

PubMed

Sakai, Miho; Hayakawa, Yoshihiro; Funada, Yasuhiro; Ando, Takashi; Fukusaki, Eiichiro; Bamba, Takeshi

2017-09-15

In this study, we propose a novel variable sample injection system based on full-loop injection, named the split-flow sample introduction system, for application in supercritical fluid chromatography (SFC). In this system, the mobile phase is split by the differential pressure between two back pressure regulators (BPRs) after full-loop injection suitable for SFC, and this differential pressure determines the introduction rate. Nine compounds with a wide range of characteristics were introduced with high reproducibility and universality, confirming that a robust variable sample injection system was achieved. We also investigated the control factors of our proposed system. Sample introduction was controlled by the ratio between the column-side pressure drops in splitless and split flow, ΔP columnsideinsplitless and ΔP columnsideinsplit , respectively, where ΔP columnsideinsplitless is related to the mobile phase flow rate and composition and the column resistance. When all other conditions are kept constant, increasing the make-up flow induces an additional pressure drop on the column side of the system, which leads to a reduced column-side flow rate, and hence decreased the amount of sample injected, even when the net pressure drop on the column side remains the same. Thus, sample introduction could be highly controlled at low sample introduction rate, regardless of the introduction conditions. This feature is advantageous because, as a control factor, the solvent in the make-up pump is independent of the column-side pressure drop. Copyright © 2017. Published by Elsevier B.V.

Assessment of coarse sediment mobility in the Black Canyon of the Gunnison River, Colorado.

PubMed

Dubinski, Ian M; Wohl, Ellen

2007-07-01

The Gunnison River in the Black Canyon of the Gunnison National Park (BCNP) near Montrose, Colorado is a mixed gravel and bedrock river with ephemeral side tributaries. Flow rates are controlled immediately upstream by a diversion tunnel and three reservoirs. The management of the hydraulic control structures has decreased low-frequency, high-stage flows, which are the dominant geomorphic force in bedrock channel systems. We developed a simple model to estimate the extent of sediment mobilization at a given flow in the BCNP and to evaluate changes in the extent and frequency of sediment mobilization for flow regimes before and after flow regulation in 1966. Our methodology provides a screening process for identifying and prioritizing areas in terms of sediment mobility criteria when more precise systematic field data are unavailable. The model uses the ratio between reach-averaged bed shear stress and critical shear stress to estimate when a particular grain size is mobilized for a given reach. We used aerial photography from 1992, digital elevation models, and field surveys to identify individual reaches and estimate reach-averaged hydraulic geometry. Pebble counts of talus and debris fan deposits were used to estimate regional colluvial grain-size distributions. Our results show that the frequency of flows mobilizing river bank sediment along a majority of the Gunnison River in the BCNP has significantly declined since 1966. The model results correspond well to those obtained from more detailed, site-specific field studies carried out by other investigators. Decreases in the frequency of significant sediment-mobilizing flows were more pronounced for regions within the BCNP where the channel gradient is lower. Implications of these results for management include increased risk of encroachment of vegetation on the active channel and long-term channel narrowing by colluvial deposits. It must be recognized that our methodology represents a screening of regional differences in sediment mobility. More precise estimates of hydraulic and sediment parameters would likely be required for dictating quantitative management objectives within the context of sediment mobility and sensitivity to changes in the flow regime.

Locations of ectopic beats coincide with spatial gradients of NADH in a regional model of low-flow reperfusion.

PubMed

Kay, Matthew; Swift, Luther; Martell, Brian; Arutunyan, Ara; Sarvazyan, Narine

2008-05-01

We studied the origins of ectopic beats during low-flow reperfusion after acute regional ischemia in excised rat hearts. The left anterior descending coronary artery was cannulated. Perfusate was delivered to the cannula using an high-performance liquid chromatography pump. This provided not only precise control of flow rate but also avoided mechanical artifacts associated with vessel occlusion and deocclusion. Optical mapping of epicardial transmembrane potential served to identify activation wavefronts. Imaging of NADH fluorescence was used to quantify local ischemia. Our experiments suggest that low-flow reperfusion of ischemic myocardium leads to a highly heterogeneous ischemic substrate and that the degree of ischemia between adjacent patches of tissue changes in time. In contrast to transient ectopic activity observed during full-flow reperfusion, persistent ectopic arrhythmias were observed during low-flow reperfusion. The origins of ectopic beats were traceable to areas of high spatial gradients of changes in NADH fluorescence caused by low-flow reperfusion.

[Feasibility Study on Digital Signal Processor and Gear Pump of Uroflowmeter Calibration Device].

PubMed

Yuan, Qing; Ji, Jun; Gao, Jiashuo; Wang, Lixin; Xiao, Hong

2016-08-01

It will cause hidden trouble on clinical application if the uroflowmeter is out of control.This paper introduces a scheme of uroflowmeter calibration device based on digital signal processor(DSP)and gear pump and shows studies of its feasibility.According to the research plan,we analyzed its stability,repeatability and linearity by building a testing system and carried out experiments on it.The flow test system is composed of DSP,gear pump and other components.The test results showed that the system could produce a stable water flow with high precision of repeated measurement and different flow rate.The test system can calibrate the urine flow rate well within the range of 9~50mL/s which has clinical significance,and the flow error is less than 1%,which meets the technical requirements of the calibration apparatus.The research scheme of uroflowmeter calibration device on DSP and gear pump is feasible.

Detachably assembled microfluidic device for perfusion culture and post-culture analysis of a spheroid array.

PubMed

Sakai, Yusuke; Hattori, Koji; Yanagawa, Fumiki; Sugiura, Shinji; Kanamori, Toshiyuki; Nakazawa, Kohji

2014-07-01

Microfluidic devices permit perfusion culture of three-dimensional (3D) tissue, mimicking the flow of blood in vascularized 3D tissue in our body. Here, we report a microfluidic device composed of a two-part microfluidic chamber chip and multi-microwell array chip able to be disassembled at the culture endpoint. Within the microfluidic chamber, an array of 3D tissue aggregates (spheroids) can be formed and cultured under perfusion. Subsequently, detailed post-culture analysis of the spheroids collected from the disassembled device can be performed. This device facilitates uniform spheroid formation, growth analysis in a high-throughput format, controlled proliferation via perfusion flow rate, and post-culture analysis of spheroids. We used the device to culture spheroids of human hepatocellular carcinoma (HepG2) cells under two controlled perfusion flow rates. HepG2 spheroids exhibited greater cell growth at higher perfusion flow rates than at lower perfusion flow rates, and exhibited different metabolic activity and mRNA and protein expression under the different flow rate conditions. These results show the potential of perfusion culture to precisely control the culture environment in microfluidic devices. The construction of spheroid array chambers allows multiple culture conditions to be tested simultaneously, with potential applications in toxicity and drug screening. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flow-injection analysis of catecholamine secretion from bovine adrenal medulla cells on microbeads.

PubMed

Herrera, M; Kao, L S; Curran, D J; Westhead, E W

1985-01-01

Bovine adrenal medullary cells have been cultured on microbeads which are placed in a low-volume flow system for measurements of stimulation-response parameters. Electronically controlled stream switching allows stimulation of cells with pulse lengths from 1 s to many minutes; pulses may be repeated indefinitely. Catecholamines secreted are detected by an electrochemical detector downstream from the cells. This flow-injection analysis technique provides a new level of sensitivity and precision for measurement of kinetic parameters of secretion. A manual injection valve allows stimulation by higher levels of stimulant in the presence of constant low levels of stimulant. Such experiments show interesting differences between the effects of K+ and acetylcholine on cells partially desensitized to acetylcholine.

Determination of the precision error of the pulmonary artery thermodilution catheter using an in vitro continuous flow test rig.

PubMed

Yang, Xiao-Xing; Critchley, Lester A; Joynt, Gavin M

2011-01-01

Thermodilution cardiac output using a pulmonary artery catheter is the reference method against which all new methods of cardiac output measurement are judged. However, thermodilution lacks precision and has a quoted precision error of ± 20%. There is uncertainty about its true precision and this causes difficulty when validating new cardiac output technology. Our aim in this investigation was to determine the current precision error of thermodilution measurements. A test rig through which water circulated at different constant rates with ports to insert catheters into a flow chamber was assembled. Flow rate was measured by an externally placed transonic flowprobe and meter. The meter was calibrated by timed filling of a cylinder. Arrow and Edwards 7Fr thermodilution catheters, connected to a Siemens SC9000 cardiac output monitor, were tested. Thermodilution readings were made by injecting 5 mL of ice-cold water. Precision error was divided into random and systematic components, which were determined separately. Between-readings (random) variability was determined for each catheter by taking sets of 10 readings at different flow rates. Coefficient of variation (CV) was calculated for each set and averaged. Between-catheter systems (systematic) variability was derived by plotting calibration lines for sets of catheters. Slopes were used to estimate the systematic component. Performances of 3 cardiac output monitors were compared: Siemens SC9000, Siemens Sirecust 1261, and Philips MP50. Five Arrow and 5 Edwards catheters were tested using the Siemens SC9000 monitor. Flow rates between 0.7 and 7.0 L/min were studied. The CV (random error) for Arrow was 5.4% and for Edwards was 4.8%. The random precision error was ± 10.0% (95% confidence limits). CV (systematic error) was 5.8% and 6.0%, respectively. The systematic precision error was ± 11.6%. The total precision error of a single thermodilution reading was ± 15.3% and ± 13.0% for triplicate readings. Precision error increased by 45% when using the Sirecust monitor and 100% when using the Philips monitor. In vitro testing of pulmonary artery catheters enabled us to measure both the random and systematic error components of thermodilution cardiac output measurement, and thus calculate the precision error. Using the Siemens monitor, we established a precision error of ± 15.3% for single and ± 13.0% for triplicate reading, which was similar to the previous estimate of ± 20%. However, this precision error was significantly worsened by using the Sirecust and Philips monitors. Clinicians should recognize that the precision error of thermodilution cardiac output is dependent on the selection of catheter and monitor model.

Fast Gas Replacement in Plasma Process Chamber by Improving Gas Flow Pattern

NASA Astrophysics Data System (ADS)

Morishita, Sadaharu; Goto, Tetsuya; Akutsu, Isao; Ohyama, Kenji; Ito, Takashi; Ohmi, Tadahiro

2009-01-01

The precise and high-speed alteration of various gas species is important for realizing precise and well-controlled multiprocesses in a single plasma process chamber with high throughput. The gas replacement times in the replacement of N2 by Ar and that of H2 by Ar are measured in a microwave excited high-density and low electron-temperature plasma process chamber at various working pressures and gas flow rates, incorporating a new gas flow control system, which can avoid overshoot of the gas pressure in the chamber immediately after the valve operation, and a gradational lead screw booster pump, which can maintain excellent pumping capability for various gas species including lightweight gases such as H2 in a wide pressure region from 10-1 to 104 Pa. Furthermore, to control the gas flow pattern in the chamber, upper ceramic shower plates, which have thousands of very fine gas injection holes (numbers of 1200 and 2400) formed with optimized allocation on the plates, are adopted, while the conventional gas supply method in the microwave-excited plasma chamber uses many holes only opened at the sidewall of the chamber (gas ring). It has been confirmed that, in the replacement of N2 by Ar, a short replacement time of approximately 1 s in the cases of 133 and 13.3 Pa and approximately 3 s in the case of 4 Pa can be achieved when the upper shower plate has 2400 holes, while a replacement time longer than approximately 10 s is required for all pressure cases where the gas ring is used. In addition, thanks to the excellent pumping capability of the gradational lead screw booster pump for lightweight gases, it has also been confirmed that the replacement time of H2 by Ar is almost the same as that of N2 by Ar.

Morphological tuning of polymeric nanoparticles via microfluidic platform for fuel cell applications.

PubMed

Hasani-Sadrabadi, Mohammad Mahdi; Majedi, Fatemeh Sadat; VanDersarl, Jules John; Dashtimoghadam, Erfan; Ghaffarian, S Reza; Bertsch, Arnaud; Moaddel, Homayoun; Renaud, Philippe

2012-11-21

At nanoscale length scales, the properties of particles change rapidly with the slightest change in dimension. The use of a microfluidic platform enables precise control of sub-100 nm organic nanoparticles (NPs) based on polybenzimidazole. Using hydrodynamic flow focusing, we can control the size and shape of the NPs, which in turn controls a number of particle material properties. The anhydrous proton-conducting nature of the prepared NPs allowed us to make a high-performance ion exchange membrane for fuel cell applications, and microfluidic tuning of the NPs allowed us subsequently to tune the fuel cell performance.

Multiparametric Flow System for the Automated Determination of Sodium, Potassium, Calcium, and Magnesium in Large-Volume Parenteral Solutions and Concentrated Hemodialysis Solutions

PubMed Central

Pistón, Mariela; Dol, Isabel

2006-01-01

A multiparametric flow system based on multicommutation and binary sampling has been designed for the automated determination of sodium, potassium, calcium, and magnesium in large-volume parenteral solutions and hemodialysis concentrated solutions. The goal was to obtain a computer-controlled system capable of determining the four metals without extensive modifications. The system involved the use of five solenoid valves under software control, allowing the establishment of the appropriate flow conditions for each analyte, that is, sample size, dilution, reagent addition, and so forth. Detection was carried out by either flame atomic emission spectrometry (sodium, potassium) or flame atomic absorption spectrometry (calcium, magnesium). The influence of several operating parameters was studied. Validation was carried out by analyzing artificial samples. Figures of merit obtained include linearity, accuracy, precision, and sampling frequency. Linearity was satisfactory: sodium, r 2 >0.999 ( 0.5 – 3.5 g/L), potassium, r 2 >0.996 (50–150 mg/L), calcium, r 2 >0.999 (30–120 mg/L), and magnesium, r 2 >0.999 (20–40 mg/L). Precision ( s r , %, n=5 ) was better than 2.1 %, and accuracy (evaluated through recovery assays) was in the range of 99.8 %– 101.0 % (sodium), 100.8 – 102.5 % (potassium), 97.3 %– 101.3 % (calcium), and 97.1 %– 99.8 % (magnesium). Sampling frequencies ( h −1 ) were 70 (sodium), 75 (potassium), 70 (calcium), and 58 (magnesium). According to the results obtained, the use of an automated multiparametric system based on multicommutation offers several advantages for the quality control of large-volume parenteral solutions and hemodialysis concentrated solutions. PMID:17671619

[Application of asymmetrical flow field-flow fractionation for size characterization of low density lipoprotein in egg yolk plasma].

PubMed

Zhang, Wenhui; Cai, Chunxue; Wang, Jing; Mao, Zhen; Li, Yueqiu; Ding, Liang; Shen, Shigang; Dou, Haiyang

2017-08-08

Home-made asymmetrical flow field-flow fractionation (AF4) system, online coupled with ultraviolet/visible (UV/Vis) detector was employed for the separation and size characterization of low density lipoprotein (LDL) in egg yolk plasma. At close to natural condition of egg yolk, the effects of cross flow rate, sample loading, and type of membrane on the size distribution of LDL were investigated. Under the optimal operation conditions, AF4-UV/Vis provides the size distribution of LDL. Moreover, the precision of AF4-UV/Vis method proposed in this work for the analysis of LDL in egg yolk plasma was evaluated. The intra-day precisions were 1.3% and 1.9% ( n =7) and the inter-day precisions were 2.4% and 2.3% ( n =7) for the elution peak height and elution peak area of LDL, respectively. Results reveal that AF4-UV/Vis is a useful tool for the separation and size characterization of LDL in egg yolk plasma.

Preferential paths in yield stress fluid flow through a porous medium

NASA Astrophysics Data System (ADS)

Guasto, Jeffrey; Waisbord, Nicolas; Stoop, Norbert; Dunkel, Jörn

2016-11-01

A broad range of biological, geological, and industrial materials with complex rheological properties are subjected to flow through porous media in applications ranging from oil recovery to food manufacturing. In this experimental study, we examine the flow of a model yield stress fluid (Carbopol micro-gel) through a quasi-2D porous medium, fabricated in a microfluidic channel. The flow is driven by applying a precisely-controlled pressure gradient and measured by particle tracking velocimetry, and our observations are complemented by a pore-network model of the yield stress fluid flow. While remaining unyielded at small applied pressure, the micro-gel begins to yield at a critical pressure gradient, exhibiting a single preferential flow path that percolates through the porous medium. As the applied pressure gradient increases, we observe a subsequent coarsening and invasion of the yielded, fluidized network. An examination of both the yielded network topology and pore-scale flow reveal that two cooperative phenomena are involved in sculpting the preferential flow paths: (1) the geometry of the porous microstructure, and (2) the adhesive surface interactions between the micro-gel and substrate. NSF CBET-1511340.

Speed tracking control of pneumatic motor servo systems using observation-based adaptive dynamic sliding-mode control

NASA Astrophysics Data System (ADS)

Chen, Syuan-Yi; Gong, Sheng-Sian

2017-09-01

This study aims to develop an adaptive high-precision control system for controlling the speed of a vane-type air motor (VAM) pneumatic servo system. In practice, the rotor speed of a VAM depends on the input mass air flow, which can be controlled by the effective orifice area (EOA) of an electronic throttle valve (ETV). As the control variable of a second-order pneumatic system is the integral of the EOA, an observation-based adaptive dynamic sliding-mode control (ADSMC) system is proposed to derive the differential of the control variable, namely, the EOA control signal. In the ADSMC system, a proportional-integral-derivative fuzzy neural network (PIDFNN) observer is used to achieve an ideal dynamic sliding-mode control (DSMC), and a supervisor compensator is designed to eliminate the approximation error. As a result, the ADSMC incorporates the robustness of a DSMC and the online learning ability of a PIDFNN. To ensure the convergence of the tracking error, a Lyapunov-based analytical method is employed to obtain the adaptive algorithms required to tune the control parameters of the online ADSMC system. Finally, our experimental results demonstrate the precision and robustness of the ADSMC system for highly nonlinear and time-varying VAM pneumatic servo systems.

Precision toxicology based on single cell sequencing: an evolving trend in toxicological evaluations and mechanism exploration.

PubMed

Zhang, Boyang; Huang, Kunlun; Zhu, Liye; Luo, Yunbo; Xu, Wentao

2017-07-01

In this review, we introduce a new concept, precision toxicology: the mode of action of chemical- or drug-induced toxicity can be sensitively and specifically investigated by isolating a small group of cells or even a single cell with typical phenotype of interest followed by a single cell sequencing-based analysis. Precision toxicology can contribute to the better detection of subtle intracellular changes in response to exogenous substrates, and thus help researchers find solutions to control or relieve the toxicological effects that are serious threats to human health. We give examples for single cell isolation and recommend laser capture microdissection for in vivo studies and flow cytometric sorting for in vitro studies. In addition, we introduce the procedures for single cell sequencing and describe the expected application of these techniques to toxicological evaluations and mechanism exploration, which we believe will become a trend in toxicology.

Solenoid Driven Pressure Valve System: Toward Versatile Fluidic Control in Paper Microfluidics.

PubMed

Kim, Taehoon H; Hahn, Young Ki; Lee, Jungmin; van Noort, Danny; Kim, Minseok S

2018-02-20

As paper-based diagnostics has become predominantly driven by more advanced microfluidic technology, many of the research efforts are still focused on developing reliable and versatile fluidic control devices, apart from improving sensitivity and reproducibility. In this work, we introduce a novel and robust paper fluidic control system enabling versatile fluidic control. The system comprises a linear push-pull solenoid and an Arduino Uno microcontroller. The precisely controlled pressure exerted on the paper stops the flow. We first determined the stroke distance of the solenoid to obtain a constant pressure while examining the fluidic time delay as a function of the pressure. Results showed that strips of grade 1 chromatography paper had superior reproducibility in fluid transport. Next, we characterized the reproducibility of the fluidic velocity which depends on the type and grade of paper used. As such, we were able to control the flow velocity on the paper and also achieve a complete stop of flow with a pressure over 2.0 MPa. Notably, after the actuation of the pressure driven valve (PDV), the previously pressed area regained its original flow properties. This means that, even on a previously pressed area, multiple valve operations can be successfully conducted. To the best of our knowledge, this is the first demonstration of an active and repetitive valve operation in paper microfluidics. As a proof of concept, we have chosen to perform a multistep detection system in the form of an enzyme-linked immunosorbent assay with mouse IgG as the target analyte.

Propellant Feed Subsystem for a 26 kW flight arcjet propulsion system

NASA Astrophysics Data System (ADS)

Vaughan, C. E.; Morris, J. P.

1993-06-01

The USAF arcjet ATTD program demanded the development of a low-cost ammonia Propellant Feed Subsystem (PFS). A flow rate of 240 +/- 5 mg/sec during a total of ten 15-min ammonia outflows was required for the flight mission. The precision of the flow tolerance required a departure from the design of previous ammonia propellant feed systems. Since a propellant management device was not used, thermocapillary forces were explored as a means to limit outflow of liquid phase ammonia. A high energy density feedline heater with an internal wick was developed to guarantee that only gas phase propellant would reach the arcjet. A digital control algorithm was developed to implement bang-bang control of mass flow rate metered by a sonic venturi. Development tests of this system have been completed. The system is capable of continuous gas phase outflows regardless of orientation. Integrated tests with the arcjet and power conditioning unit have also been successfully completed.

Adaptive Grid Generation Using Elliptic Generating Equations with Precise Coordinate Controls

DTIC Science & Technology

1986-07-08

nonhomogeneous terms, which are strong eration that are of critical importance in choosing a and typically greatly slow the iterative convergence grid...computational mechan- calcuiauons. particulary three-dimensionai turbuient studies. ics in October 1989. 1 do not : hink that the overall cost of -te...flow in gas turbine diffusers, and from the National Science Foundation (Mathematics Division) on "Robust and Fast Numerical Grid Generation". The

Comparison of Models for Spacer Grid Pressure Loss in Nuclear Fuel Bundles for One and Two-Phase Flows

NASA Astrophysics Data System (ADS)

Maskal, Alan B.

Spacer grids maintain the structural integrity of the fuel rods within fuel bundles of nuclear power plants. They can also improve flow characteristics within the nuclear reactor core. However, spacer grids add reactor coolant pressure losses, which require estimation and engineering into the design. Several mathematical models and computer codes were developed over decades to predict spacer grid pressure loss. Most models use generalized characteristics, measured by older, less precise equipment. The study of OECD/US-NRC BWR Full-Size Fine Mesh Bundle Tests (BFBT) provides updated and detailed experimental single and two-phase results, using technically advanced flow measurements for a wide range of boundary conditions. This thesis compares the predictions from the mathematical models to the BFBT experimental data by utilizing statistical formulae for accuracy and precision. This thesis also analyzes the effects of BFBT flow characteristics on spacer grids. No single model has been identified as valid for all flow conditions. However, some models' predictions perform better than others within a range of flow conditions, based on the accuracy and precision of the models' predictions. This study also demonstrates that pressure and flow quality have a significant effect on two-phase flow spacer grid models' biases.

Building SDN-Based Agricultural Vehicular Sensor Networks Based on Extended Open vSwitch.

PubMed

Huang, Tao; Yan, Siyu; Yang, Fan; Pan, Tian; Liu, Jiang

2016-01-19

Software-defined vehicular sensor networks in agriculture, such as autonomous vehicle navigation based on wireless multi-sensor networks, can lead to more efficient precision agriculture. In SDN-based vehicle sensor networks, the data plane is simplified and becomes more efficient by introducing a centralized controller. However, in a wireless environment, the main controller node may leave the sensor network due to the dynamic topology change or the unstable wireless signal, leaving the rest of network devices without control, e.g., a sensor node as a switch may forward packets according to stale rules until the controller updates the flow table entries. To solve this problem, this paper proposes a novel SDN-based vehicular sensor networks architecture which can minimize the performance penalty of controller connection loss. We achieve this by designing a connection state detection and self-learning mechanism. We build prototypes based on extended Open vSwitch and Ryu. The experimental results show that the recovery time from controller connection loss is under 100 ms and it keeps rule updating in real time with a stable throughput. This architecture enhances the survivability and stability of SDN-based vehicular sensor networks in precision agriculture.

Building SDN-Based Agricultural Vehicular Sensor Networks Based on Extended Open vSwitch

PubMed Central

Huang, Tao; Yan, Siyu; Yang, Fan; Pan, Tian; Liu, Jiang

2016-01-01

Software-defined vehicular sensor networks in agriculture, such as autonomous vehicle navigation based on wireless multi-sensor networks, can lead to more efficient precision agriculture. In SDN-based vehicle sensor networks, the data plane is simplified and becomes more efficient by introducing a centralized controller. However, in a wireless environment, the main controller node may leave the sensor network due to the dynamic topology change or the unstable wireless signal, leaving the rest of network devices without control, e.g., a sensor node as a switch may forward packets according to stale rules until the controller updates the flow table entries. To solve this problem, this paper proposes a novel SDN-based vehicular sensor networks architecture which can minimize the performance penalty of controller connection loss. We achieve this by designing a connection state detection and self-learning mechanism. We build prototypes based on extended Open vSwitch and Ryu. The experimental results show that the recovery time from controller connection loss is under 100 ms and it keeps rule updating in real time with a stable throughput. This architecture enhances the survivability and stability of SDN-based vehicular sensor networks in precision agriculture. PMID:26797616

A site-specific slurry application technique on grassland and on arable crops.

PubMed

Schellberg, Jürgen; Lock, Reiner

2009-01-01

There is evidence that unequal slurry application on agricultural land contributes to N losses to the environment. Heterogeneity within fields demands adequate response by means of variable rate application. A technique is presented which allows site-specific application of slurry on grassland and arable land based on pre-defined application maps. The system contains a valve controlling flow rate by an on-board PC. During operation, flow rate is measured and scaled against set point values given in the application map together with the geographic position of the site. The systems worked sufficiently precise at a flow rate between 0 and 25 l s(-1) and an offset of actual slurry flow from set point values between 0.33 and 0.67 l s(-1). Long-term experimentation is required to test if site-specific application de facto reduces N surplus within fields and so significantly contributes to the unloading of N in agricultural areas.

Sewage Monitors

NASA Technical Reports Server (NTRS)

1987-01-01

Every U.S. municipality must determine how much waste water it is processing and more importantly, how much is going unprocessed into lakes and streams either because of leaks in the sewer system or because the city's sewage facilities were getting more sewer flow than they were designed to handle. ADS Environmental Services, Inc.'s development of the Quadrascan Flow Monitoring System met the need for an accurate method of data collection. The system consists of a series of monitoring sensors and microcomputers that continually measure water depth at particular sewer locations and report their findings to a central computer. This provides precise information to city managers on overall flow, flow in any section of the city, location and severity of leaks and warnings of potential overload. The core technology has been expanded upon in terms of both technical improvements, and functionality for new applications, including event alarming and control for critical collection system management problems.

Pressure data for four analytically defined arrow wings in supersonic flow. [Langley Unitary Plan Wind Tunnel tests

NASA Technical Reports Server (NTRS)

Townsend, J. C.

1980-01-01

In order to provide experimental data for comparison with newly developed finite difference methods for computing supersonic flows over aircraft configurations, wind tunnel tests were conducted on four arrow wing models. The models were machined under numeric control to precisely duplicate analytically defined shapes. They were heavily instrumented with pressure orifices at several cross sections ahead of and in the region where there is a gap between the body and the wing trailing edge. The test Mach numbers were 2.36, 2.96, and 4.63. Tabulated pressure data for the complete test series are presented along with selected oil flow photographs. Comparisons of some preliminary numerical results at zero angle of attack show good to excellent agreement with the experimental pressure distributions.

Continuous hyperpolarization with parahydrogen in a membrane reactor

NASA Astrophysics Data System (ADS)

Lehmkuhl, Sören; Wiese, Martin; Schubert, Lukas; Held, Mathias; Küppers, Markus; Wessling, Matthias; Blümich, Bernhard

2018-06-01

Hyperpolarization methods entail a high potential to boost the sensitivity of NMR. Even though the "Signal Amplification by Reversible Exchange" (SABRE) approach uses para-enriched hydrogen, p-H2, to repeatedly achieve high polarization levels on target molecules without altering their chemical structure, such studies are often limited to batch experiments in NMR tubes. Alternatively, this work introduces a continuous flow setup including a membrane reactor for the p-H2, supply and consecutive detection in a 1 T NMR spectrometer. Two SABRE substrates pyridine and nicotinamide were hyperpolarized, and more than 1000-fold signal enhancement was found. Our strategy combines low-field NMR spectrometry and a membrane flow reactor. This enables precise control of the experimental conditions such as liquid and gas pressures, and volume flow for ensuring repeatable maximum polarization.

In Situ Spatiotemporal Mapping of Flow Fields around Seeded Stem Cells at the Subcellular Length Scale

PubMed Central

Song, Min Jae; Dean, David; Knothe Tate, Melissa L.

2010-01-01

A major hurdle to understanding and exploiting interactions between the stem cell and its environment is the lack of a tool for precise delivery of mechanical cues concomitant to observing sub-cellular adaptation of structure. These studies demonstrate the use of microscale particle image velocimetry (μ-PIV) for in situ spatiotemporal mapping of flow fields around mesenchymal stem cells, i.e. murine embryonic multipotent cell line C3H10T1/2, at the subcellular length scale, providing a tool for real time observation and analysis of stem cell adaptation to the prevailing mechanical milieu. In the absence of cells, computational fluid dynamics (CFD) predicts flow regimes within 12% of μ-PIV measures, achieving the technical specifications of the chamber and the flow rates necessary to deliver target shear stresses at a particular height from the base of the flow chamber. However, our μ-PIV studies show that the presence of cells per se as well as the density at which cells are seeded significantly influences local flow fields. Furthermore, for any given cell or cell seeding density, flow regimes vary significantly along the vertical profile of the cell. Hence, the mechanical milieu of the stem cell exposed to shape changing shear stresses, induced by fluid drag, varies with respect to proximity of surrounding cells as well as with respect to apical height. The current study addresses a previously unmet need to predict and observe both flow regimes as well as mechanoadaptation of cells in flow chambers designed to deliver precisely controlled mechanical signals to live cells. An understanding of interactions and adaptation in response to forces at the interface between the surface of the cell and its immediate local environment may be key for de novo engineering of functional tissues from stem cell templates as well as for unraveling the mechanisms underlying multiscale development, growth and adaptation of organisms. PMID:20862249

Portable Dew Point Mass Spectrometry System for Real-Time Gas and Moisture Analysis

NASA Technical Reports Server (NTRS)

Arkin, C.; Gillespie, Stacey; Ratzel, Christopher

2010-01-01

A portable instrument incorporates both mass spectrometry and dew point measurement to provide real-time, quantitative gas measurements of helium, nitrogen, oxygen, argon, and carbon dioxide, along with real-time, quantitative moisture analysis. The Portable Dew Point Mass Spectrometry (PDP-MS) system comprises a single quadrupole mass spectrometer and a high vacuum system consisting of a turbopump and a diaphragm-backing pump. A capacitive membrane dew point sensor was placed upstream of the MS, but still within the pressure-flow control pneumatic region. Pressure-flow control was achieved with an upstream precision metering valve, a capacitance diaphragm gauge, and a downstream mass flow controller. User configurable LabVIEW software was developed to provide real-time concentration data for the MS, dew point monitor, and sample delivery system pressure control, pressure and flow monitoring, and recording. The system has been designed to include in situ, NIST-traceable calibration. Certain sample tubing retains sufficient water that even if the sample is dry, the sample tube will desorb water to an amount resulting in moisture concentration errors up to 500 ppm for as long as 10 minutes. It was determined that Bev-A-Line IV was the best sample line to use. As a result of this issue, it is prudent to add a high-level humidity sensor to PDP-MS so such events can be prevented in the future.

Multinode acoustic focusing for parallel flow cytometry

PubMed Central

Piyasena, Menake E.; Suthanthiraraj, Pearlson P. Austin; Applegate, Robert W.; Goumas, Andrew M.; Woods, Travis A.; López, Gabriel P.; Graves, Steven W.

2012-01-01

Flow cytometry can simultaneously measure and analyze multiple properties of single cells or particles with high sensitivity and precision. Yet, conventional flow cytometers have fundamental limitations with regards to analyzing particles larger than about 70 microns, analyzing at flow rates greater than a few hundred microliters per minute, and providing analysis rates greater than 50,000 per second. To overcome these limits, we have developed multi-node acoustic focusing flow cells that can position particles (as small as a red blood cell and as large as 107 microns in diameter) into as many as 37 parallel flow streams. We demonstrate the potential of such flow cells for the development of high throughput, parallel flow cytometers by precision focusing of flow cytometry alignment microspheres, red blood cells, and the analysis of CD4+ cellular immunophenotyping assay. This approach will have significant impact towards the creation of high throughput flow cytometers for rare cell detection applications (e.g. circulating tumor cells), applications requiring large particle analysis, and high volume flow cytometry. PMID:22239072

Microfluidic Chips Controlled with Elastomeric Microvalve Arrays

PubMed Central

Li, Nianzhen; Sip, Chris; Folch, Albert

2007-01-01

Miniaturized microfluidic systems provide simple and effective solutions for low-cost point-of-care diagnostics and high-throughput biomedical assays. Robust flow control and precise fluidic volumes are two critical requirements for these applications. We have developed microfluidic chips featuring elastomeric polydimethylsiloxane (PDMS) microvalve arrays that: 1) need no extra energy source to close the fluidic path, hence the loaded device is highly portable; and 2) allow for microfabricating deep (up to 1 mm) channels with vertical sidewalls and resulting in very precise features. The PDMS microvalves-based devices consist of three layers: a fluidic layer containing fluidic paths and microchambers of various sizes, a control layer containing the microchannels necessary to actuate the fluidic path with microvalves, and a middle thin PDMS membrane that is bound to the control layer. Fluidic layer and control layers are made by replica molding of PDMS from SU-8 photoresist masters, and the thin PDMS membrane is made by spinning PDMS at specified heights. The control layer is bonded to the thin PDMS membrane after oxygen activation of both, and then assembled with the fluidic layer. The microvalves are closed at rest and can be opened by applying negative pressure (e.g., house vacuum). Microvalve closure and opening are automated via solenoid valves controlled by computer software. Here, we demonstrate two microvalve-based microfluidic chips for two different applications. The first chip allows for storing and mixing precise sub-nanoliter volumes of aqueous solutions at various mixing ratios. The second chip allows for computer-controlled perfusion of microfluidic cell cultures. The devices are easy to fabricate and simple to control. Due to the biocompatibility of PDMS, these microchips could have broad applications in miniaturized diagnostic assays as well as basic cell biology studies. PMID:18989408

Further experiments for mean velocity profile of pipe flow at high Reynolds number

NASA Astrophysics Data System (ADS)

Furuichi, N.; Terao, Y.; Wada, Y.; Tsuji, Y.

2018-05-01

This paper reports further experimental results obtained in high Reynolds number actual flow facility in Japan. The experiments were performed in a pipe flow with water, and the friction Reynolds number was varied up to Reτ = 5.3 × 104. This high Reynolds number was achieved by using water as the working fluid and adopting a large-diameter pipe (387 mm) while controlling the flow rate and temperature with high accuracy and precision. The streamwise velocity was measured by laser Doppler velocimetry close to the wall, and the mean velocity profile, called log-law profile U+ = (1/κ) ln(y+) + B, is especially focused. After careful verification of the mean velocity profiles in terms of the flow rate accuracy and an evaluation of the consistency of the present results with those from previously measurements in a smaller pipe (100 mm), it was found that the value of κ asymptotically approaches a constant value of κ = 0.384.

Flux-Feedback Magnetic-Suspension Actuator

NASA Technical Reports Server (NTRS)

Groom, Nelson J.

1990-01-01

Flux-feedback magnetic-suspension actuator provides magnetic suspension and control forces having linear transfer characteristics between force command and force output over large range of gaps. Hall-effect devices used as sensors for electronic feedback circuit controlling currents flowing in electromagnetic windings to maintain flux linking suspended element at substantially constant value independent of changes in length of gap. Technique provides effective method for maintenance of constant flux density in gap and simpler than previous methods. Applications include magnetic actuators for control of shapes and figures of antennas and of precise segmented reflectors, magnetic suspensions in devices for storage of angular momentum and/or kinetic energy, and systems for control, pointing, and isolation of instruments.

A highly versatile and easily configurable system for plant electrophysiology.

PubMed

Gunsé, Benet; Poschenrieder, Charlotte; Rankl, Simone; Schröeder, Peter; Rodrigo-Moreno, Ana; Barceló, Juan

2016-01-01

In this study we present a highly versatile and easily configurable system for measuring plant electrophysiological parameters and ionic flow rates, connected to a computer-controlled highly accurate positioning device. The modular software used allows easy customizable configurations for the measurement of electrophysiological parameters. Both the operational tests and the experiments already performed have been fully successful and rendered a low noise and highly stable signal. Assembly, programming and configuration examples are discussed. The system is a powerful technique that not only gives precise measuring of plant electrophysiological status, but also allows easy development of ad hoc configurations that are not constrained to plant studies. •We developed a highly modular system for electrophysiology measurements that can be used either in organs or cells and performs either steady or dynamic intra- and extracellular measurements that takes advantage of the easiness of visual object-oriented programming.•High precision accuracy in data acquisition under electrical noisy environments that allows it to run even in a laboratory close to electrical equipment that produce electrical noise.•The system makes an improvement of the currently used systems for monitoring and controlling high precision measurements and micromanipulation systems providing an open and customizable environment for multiple experimental needs.

The Azimuth Structure of Nuclear Collisions — I

NASA Astrophysics Data System (ADS)

Trainor, Thomas A.; Kettler, David T.

We describe azimuth structure commonly associated with elliptic and directed flow in the context of 2D angular autocorrelations for the purpose of precise separation of so-called nonflow (mainly minijets) from flow. We extend the Fourier-transform description of azimuth structure to include power spectra and autocorrelations related by the Wiener-Khintchine theorem. We analyze several examples of conventional flow analysis in that context and question the relevance of reaction plane estimation to flow analysis. We introduce the 2D angular autocorrelation with examples from data analysis and describe a simulation exercise which demonstrates precise separation of flow and nonflow using the 2D autocorrelation method. We show that an alternative correlation measure based on Pearson's normalized covariance provides a more intuitive measure of azimuth structure.

A novel planar flow cell for studies of biofilm heterogeneity and flow-biofilm interactions

PubMed Central

Zhang, Wei; Sileika, Tadas S.; Chen, Cheng; Liu, Yang; Lee, Jisun; Packman, Aaron I.

2012-01-01

Biofilms are microbial communities growing on surfaces, and are ubiquitous in nature, in bioreactors, and in human infection. Coupling between physical, chemical, and biological processes is known to regulate the development of biofilms; however, current experimental systems do not provide sufficient control of environmental conditions to enable detailed investigations of these complex interactions. We developed a novel planar flow cell that supports biofilm growth under complex two-dimensional fluid flow conditions. This device provides precise control of flow conditions and can be used to create well-defined physical and chemical gradients that significantly affect biofilm heterogeneity. Moreover, the top and bottom of the flow chamber are transparent, so biofilm growth and flow conditions are fully observable using non-invasive confocal microscopy and high-resolution video imaging. To demonstrate the capability of the device, we observed the growth of Pseudomonas aeruginosa biofilms under imposed flow gradients. We found a positive relationship between patterns of fluid velocity and biofilm biomass because of faster microbial growth under conditions of greater local nutrient influx, but this relationship eventually reversed because high hydrodynamic shear leads to the detachment of cells from the surface. These results reveal that flow gradients play a critical role in the development of biofilm communities. By providing new capability for observing biofilm growth, solute and particle transport, and net chemical transformations under user-specified environmental gradients, this new planar flow cell system has broad utility for studies of environmental biotechnology and basic biofilm microbiology, as well as applications in bioreactor design, environmental engineering, biogeochemistry, geomicrobiology, and biomedical research. PMID:21656713

Simple and ultra-fast recognition and quantitation of compounded monoclonal antibodies: Application to flow injection analysis combined to UV spectroscopy and matching method.

PubMed

Jaccoulet, E; Schweitzer-Chaput, A; Toussaint, B; Prognon, P; Caudron, E

2018-09-01

Compounding of monoclonal antibody (mAbs) constantly increases in hospital. Quality control (QC) of the compounded mAbs based on quantification and identification is required to prevent potential errors and fast method is needed to manage outpatient chemotherapy administration. A simple and ultra-fast (less than 30 s) method using flow injection analysis associated to least square matching method issued from the analyzer software was performed and evaluated for the routine hospital QC of three compounded mAbs: bevacizumab, infliximab and rituximab. The method was evaluated through qualitative and quantitative parameters. Preliminary analysis of the UV absorption and second derivative spectra of the mAbs allowed us to adapt analytical conditions according to the therapeutic range of the mAbs. In terms of quantitative QC, linearity, accuracy and precision were assessed as specified in ICH guidelines. Very satisfactory recovery was achieved and the RSD (%) of the intermediate precision were less than 1.1%. Qualitative analytical parameters were also evaluated in terms of specificity, sensitivity and global precision through a matrix of confusion. Results showed to be concentration and mAbs dependant and excellent (100%) specificity and sensitivity were reached within specific concentration range. Finally, routine application on "real life" samples (n = 209) from different batch of the three mAbs complied with the specifications of the quality control i.e. excellent identification (100%) and ± 15% of targeting concentration belonging to the calibration range. The successful use of the combination of second derivative spectroscopy and partial least square matching method demonstrated the interest of FIA for the ultra-fast QC of mAbs after compounding using matching method. Copyright © 2018 Elsevier B.V. All rights reserved.

Sensitivity analysis for the control of supersonic impinging jet noise

NASA Astrophysics Data System (ADS)

Nichols, Joseph W.; Hildebrand, Nathaniel

2016-11-01

The dynamics of a supersonic jet that impinges perpendicularly on a flat plate depend on complex interactions between fluid turbulence, shock waves, and acoustics. Strongly organized oscillations emerge, however, and they induce loud, often damaging, tones. We investigate this phenomenon using unstructured, high-fidelity Large Eddy Simulation (LES) and global stability analysis. Our flow configurations precisely match laboratory experiments with nozzle-to-wall distances of 4 and 4.5 jet diameters. We use multi-block shift-and-invert Arnoldi iteration to extract both direct and adjoint global modes that extend upstream into the nozzle. The frequency of the most unstable global mode agrees well with that of the emergent oscillations in the LES. We compute the "wavemaker" associated with this mode by multiplying it by its corresponding adjoint mode. The wavemaker shows that this instability is most sensitive to changes in the base flow slightly downstream of the nozzle exit. By modifying the base flow in this region, we then demonstrate that the flow can indeed be stabilized. This explains the success of microjets as an effective noise control measure when they are positioned around the nozzle lip. Computational resources were provided by the Argonne Leadership Computing Facility.

Effect of travel speed on the visual control of steering toward a goal.

PubMed

Chen, Rongrong; Niehorster, Diederick C; Li, Li

2018-03-01

Previous studies have proposed that people can use visual cues such as the instantaneous direction (i.e., heading) or future path trajectory of travel specified by optic flow or target visual direction in egocentric space to steer or walk toward a goal. In the current study, we examined what visual cues people use to guide their goal-oriented locomotion and whether their reliance on such visual cues changes as travel speed increases. We presented participants with optic flow displays that simulated their self-motion toward a target at various travel speeds under two viewing conditions in which we made target egocentric direction available or unavailable for steering. We found that for both viewing conditions, participants did not steer along a curved path toward the target such that the actual and the required path curvature to reach the target would converge when approaching the target. At higher travel speeds, participants showed a faster and larger reduction in target-heading angle and more accurate and precise steady-state control of aligning their heading specified by optic flow with the target. These findings support the claim that people use heading and target egocentric direction but not path for goal-oriented locomotion control, and their reliance on heading increases at higher travel speeds. The increased reliance on heading for goal-oriented locomotion control could be due to an increased reliability in perceiving heading from optic flow as the magnitude of flow increases with travel speed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Study on Controls of Fluids in Nanochannel via Hybrid Surface

NASA Astrophysics Data System (ADS)

Ye, Ziran

This thesis contributes to the investigation of controls of nanofluidic fluids by utilizing hybrid surface patterns in nanochannel. Nanofluidics is a core and interdisciplinary research field which manipulates, controls and analyzes fluids in nanoscale and develop potential bio/chemical applications. This thesis studies the surface-induced phenomena in nanofluidics, we use surface decoration on nanochannel walls to investigate the influences on fluid motion and further explore the fundamental physical principle of this behavior. To begin with, we designed and fabricated the nanofluidic mixer for the first time, which comprised hybrid surface patterns with different wettabilities on both top and bottom walls of nanochannel. Although microfluidic mixers have been intensively investigated, nanofluidic mixer has never been reported. Without any inside geometric structure of nanochannel, the mixing phenomenon can be achieved by the surface patterns and the mixing length can be significantly shortened comparing with micromixer. We attribute this achievement to the chaotic flows of two fluids induced by the patterned surface. The surface-related phenomena may not be so prominent on large scale, however, it is pronounced when the scale shrinks down to nanometer due to the large surface-to-volume ratio in nanochannel. In the second part of this work, based on the technology of nanofabrication and similar principle, we built up another novel method to control the speed of capillary flow in nanochannel in a quantitative manner. Surface patterns were fabricated on the nanochannel walls to slow down the capillary flow. The flow speed can be precisely controlled by modifying hydrophobicity ratio. Under the extreme surface-to-volume ratio in nanochannel, the significant surface effect on the fluid effectively reduced the speed of capillary flow without any external energy source and equipment. Such approach may be adopted for a wide variety of nanofluidicsbased biochemical analysis systems.

Liquefied Natural Gas Transfer

NASA Technical Reports Server (NTRS)

1980-01-01

Chicago Bridge & Iron Company's tanks and associated piping are parts of system for transferring liquefied natural gas from ship to shore and storing it. LNG is a "cryogenic" fluid meaning that it must be contained and transferred at very low temperatures, about 260 degrees below Fahrenheit. Before the LNG can be pumped from the ship to the storage tanks, the two foot diameter transfer pipes must be cooled in order to avoid difficulties associated with sharp differences of temperature between the supercold fluid and relatively warm pipes. Cooldown is accomplished by sending small steady flow of the cryogenic substance through the pipeline; the rate of flow must be precisely controlled or the transfer line will be subjected to undesirable thermal stress.

Note: Automated electrochemical etching and polishing of silver scanning tunneling microscope tips.

PubMed

Sasaki, Stephen S; Perdue, Shawn M; Rodriguez Perez, Alejandro; Tallarida, Nicholas; Majors, Julia H; Apkarian, V Ara; Lee, Joonhee

2013-09-01

Fabrication of sharp and smooth Ag tips is crucial in optical scanning probe microscope experiments. To ensure reproducible tip profiles, the polishing process is fully automated using a closed-loop laminar flow system to deliver the electrolytic solution to moving electrodes mounted on a motorized translational stage. The repetitive translational motion is controlled precisely on the μm scale with a stepper motor and screw-thread mechanism. The automated setup allows reproducible control over the tip profile and improves smoothness and sharpness of tips (radius 27 ± 18 nm), as measured by ultrafast field emission.

Controlled and tunable polymer particles' production using a single microfluidic device

NASA Astrophysics Data System (ADS)

Amoyav, Benzion; Benny, Ofra

2018-04-01

Microfluidics technology offers a new platform to control liquids under flow in small volumes. The advantage of using small-scale reactions for droplet generation along with the capacity to control the preparation parameters, making microfluidic chips an attractive technology for optimizing encapsulation formulations. However, one of the drawback in this methodology is the ability to obtain a wide range of droplet sizes, from sub-micron to microns using a single chip design. In fact, typically, droplet chips are used for micron-dimension particles, while nanoparticles' synthesis requires complex chips design (i.e., microreactors and staggered herringbone micromixer). Here, we introduce the development of a highly tunable and controlled encapsulation technique, using two polymer compositions, for generating particles ranging from microns to nano-size using the same simple single microfluidic chip design. Poly(lactic-co-glycolic acid) (PLGA 50:50) or PLGA/polyethylene glycol polymeric particles were prepared with focused-flow chip, yielding monodisperse particle batches. We show that by varying flow rate, solvent, surfactant and polymer composition, we were able to optimize particles' size and decrease polydispersity index, using simple chip designs with no further related adjustments or costs. Utilizing this platform, which offers tight tuning of particle properties, could offer an important tool for formulation development and can potentially pave the way towards a better precision nanomedicine.

ARM Airborne Continuous carbon dioxide measurements

DOE Data Explorer

Biraud, Sebastien

2013-03-26

The heart of the AOS CO2 Airborne Rack Mounted Analyzer System is the AOS Manifold. The AOS Manifold is a nickel coated aluminum analyzer and gas processor designed around two identical nickel-plated gas cells, one for reference gas and one for sample gas. The sample and reference cells are uniquely designed to provide optimal flushing efficiency. These cells are situated between a black-body radiation source and a photo-diode detection system. The AOS manifold also houses flow meters, pressure sensors and control valves. The exhaust from the analyzer flows into a buffer volume which allows for precise pressure control of the analyzer. The final piece of the analyzer is the demodulator board which is used to convert the DC signal generated by the analyzer into an AC response. The resulting output from the demodulator board is an averaged count of CO2 over a specified hertz cycle reported in volts and a corresponding temperature reading. The system computer is responsible for the input of commands and therefore works to control the unit functions such as flow rate, pressure, and valve control.The remainder of the system consists of compressors, reference gases, air drier, electrical cables, and the necessary connecting plumbing to provide a dry sample air stream and reference air streams to the AOS manifold.

Design of a new controller to treat the obstructive sleep apnea

NASA Astrophysics Data System (ADS)

Netzel, Thomas

2002-06-01

The obstructive sleep apnoea (OSA) is a sleep related breathing disorder caused by a relaxation of the upper airway structure during the sleep that leads to a complete closure of the upper airway. The most successful therapy is the nasal continuous positive airway pressure (nCPAP) treatment that keeps the airway opened. More recent devices use an automatic adaptation of the applied pressure. Either the forced oscillation technique (FOT) or the evaluation of the inspiration flow contour are used to evaluate the severity of obstructions. Both methods have disadvantages that may lead to wrong applied pressures. Based on the precise measurement of airflow and mask pressure during nCPAP with a Weinmann SOMNOsmart and additional polysomnography a new parameter set is presented that uses the advantage of both methods to detect the obstructive sleep apnoea. To evaluate the applicability of this parameter set to control Auto-nCPAP-devices a fuzzy-controller is designed under MATLAB/Simulink using an A/D-D/A-converter to control the blower of the SOMNOsmart during Auto-nCPAP-therapy. Obstructive events are detected and treated with a rise of nCPAP-pressure depending on the inspiratory flow requirement. The pressure is lowered after the end of flow limited phases. Although temporary low pressures no oxygen desaturation is recognized by the pulse oxymeter.

Measuring the mechanical efficiency of a working cardiac muscle sample at body temperature using a flow-through calorimeter.

PubMed

Taberner, Andrew J; Johnston, Callum M; Pham, Toan; June-Chiew Han; Ruddy, Bryan P; Loiselle, Denis S; Nielsen, Poul M F

2015-08-01

We have developed a new `work-loop calorimeter' that is capable of measuring, simultaneously, the work-done and heat production of isolated cardiac muscle samples at body temperature. Through the innovative use of thermoelectric modules as temperature sensors, the development of a low-noise fluid-flow system, and implementation of precise temperature control, the heat resolution of this device is 10 nW, an improvement by a factor of ten over previous designs. These advances have allowed us to conduct the first flow-through measurements of work output and heat dissipation from cardiac tissue at body temperature. The mechanical efficiency is found to vary with peak stress, and reaches a peak value of approximately 15 %, a figure similar to that observed in cardiac muscle at lower temperatures.

Development of a custom on-line ultrasonic vapour analyzer and flow meter for the ATLAS inner detector, with application to Cherenkov and gaseous charged particle detectors

NASA Astrophysics Data System (ADS)

Alhroob, M.; Bates, R.; Battistin, M.; Berry, S.; Bitadze, A.; Bonneau, P.; Bousson, N.; Boyd, G.; Bozza, G.; Crespo-Lopez, O.; Degeorge, C.; Deterre, C.; DiGirolamo, B.; Doubek, M.; Favre, G.; Godlewski, J.; Hallewell, G.; Hasib, A.; Katunin, S.; Langevin, N.; Lombard, D.; Mathieu, M.; McMahon, S.; Nagai, K.; O'Rourke, A.; Pearson, B.; Robinson, D.; Rossi, C.; Rozanov, A.; Strauss, M.; Vacek, V.; Zwalinski, L.

2015-03-01

Precision sound velocity measurements can simultaneously determine binary gas composition and flow. We have developed an analyzer with custom microcontroller-based electronics, currently used in the ATLAS Detector Control System, with numerous potential applications. Three instruments monitor C3F8 and CO2 coolant leak rates into the nitrogen envelopes of the ATLAS silicon microstrip and Pixel detectors. Two further instruments will aid operation of the new thermosiphon coolant recirculator: one of these will monitor air leaks into the low pressure condenser while the other will measure return vapour flow along with C3F8/C2F6 blend composition, should blend operation be necessary to protect the ATLAS silicon tracker under increasing LHC luminosity. We describe these instruments and their electronics.

Ultrafast dynamic computed tomography myelography for the precise identification of high-flow cerebrospinal fluid leaks caused by spiculated spinal osteophytes.

PubMed

Thielen, Kent R; Sillery, John C; Morris, Jonathan M; Hoxworth, Joseph M; Diehn, Felix E; Wald, John T; Rosebrock, Richard E; Yu, Lifeng; Luetmer, Patrick H

2015-03-01

Precise localization and understanding of the origin of spontaneous high-flow spinal CSF leaks is required prior to targeted treatment. This study demonstrates the utility of ultrafast dynamic CT myelography for the precise localization of high-flow CSF leaks caused by spiculated spinal osteophytes. This study reports a series of 14 patients with high-flow CSF leaks caused by spiculated spinal osteophytes who underwent ultrafast dynamic CT myelography between March 2009 and December 2010. There were 10 male and 4 female patients, with an average age of 49 years (range 37-74 years). The value of ultrafast dynamic CT myelography in depicting the CSF leak site was qualitatively assessed. In all 14 patients, ultrafast dynamic CT myelography was technically successful at precisely demonstrating the site of the CSF leak, the causative spiculated osteophyte piercing the dura, and the relationship of the implicated osteophyte to adjacent structures. Leak sites included 3 cervical, 11 thoracic, and 0 lumbar levels, with 86% of the leaks occurring from C-5 to T-7. Information obtained from the ultrafast dynamic CT myelogram was considered useful in all treated CSF leaks. Spinal osteophytes piercing the dura are a more frequent cause of high-flow CSF leaks than previously recognized. Ultrafast dynamic CT myelography adds value beyond standard dynamic myelography or digital subtraction myelography in the diagnosis and anatomical characterization of high-flow spinal CSF leaks caused by these osteophytes. This information allows for appropriate planning for percutaneous or surgical treatment.

Real-Time Variable Rate Spraying in Orchards and Vineyards: A Review

NASA Astrophysics Data System (ADS)

Wandkar, Sachin Vilas; Bhatt, Yogesh Chandra; Jain, H. K.; Nalawade, Sachin M.; Pawar, Shashikant G.

2018-06-01

Effective and efficient use of pesticides in the orchards is of concern since many years. With the conventional constant rate sprayers, equal dose of pesticide is applied to each tree. Since, there is great variation in size and shape of each tree in the orchard, trees gets either oversprayed or undersprayed. Real-time variable rate spraying technology offers pesticide application in accordance with tree size. With the help of suitable sensors, tree characteristics such as canopy volume, foliage density, etc. can be acquired and with the micro-processing unit coupled with proper algorithm, flow of electronic proportional valves can be controlled thus, controlling the flow rate of nozzles according to tree characteristics. Also, sensors can help in the detection of spaces in-between trees which allows to control the spray in spaces. Variable rate spraying helps in achieving precision in spraying operation especially inside orchards. This paper reviews the real-time variable rate spraying technology and efforts made by the various researchers for real-time variable application in the orchards and vineyards.

Real-Time Variable Rate Spraying in Orchards and Vineyards: A Review

NASA Astrophysics Data System (ADS)

Wandkar, Sachin Vilas; Bhatt, Yogesh Chandra; Jain, H. K.; Nalawade, Sachin M.; Pawar, Shashikant G.

2018-02-01

Effective and efficient use of pesticides in the orchards is of concern since many years. With the conventional constant rate sprayers, equal dose of pesticide is applied to each tree. Since, there is great variation in size and shape of each tree in the orchard, trees gets either oversprayed or undersprayed. Real-time variable rate spraying technology offers pesticide application in accordance with tree size. With the help of suitable sensors, tree characteristics such as canopy volume, foliage density, etc. can be acquired and with the micro-processing unit coupled with proper algorithm, flow of electronic proportional valves can be controlled thus, controlling the flow rate of nozzles according to tree characteristics. Also, sensors can help in the detection of spaces in-between trees which allows to control the spray in spaces. Variable rate spraying helps in achieving precision in spraying operation especially inside orchards. This paper reviews the real-time variable rate spraying technology and efforts made by the various researchers for real-time variable application in the orchards and vineyards.

Precision control of drying using rhythmic dancing of sessile nanoparticle laden droplets

NASA Astrophysics Data System (ADS)

Sanyal, Apratim; Basu, Saptarshi; Chowdhuri, Subham; Kabi, Prasenjit; Chaudhuri, Swetaprovo

2014-04-01

This work analyses the unique spatio-temporal alteration of the deposition pattern of evaporating nanoparticle laden droplets resting on a hydrophobic surface through targeted low frequency substrate vibrations. External excitation near the lowest resonant mode (n = 2) of the droplet initially de-pins and then subsequently re-pins the droplet edge creating pseudo-hydrophilicity (low contact angle). Vibration subsequently induces droplet shape oscillations (cyclic elongation and flattening) resulting in strong flow recirculation. This strong radially outward liquid flow augments nanoparticle transport, vaporization, and agglomeration near the pinned edge resulting in much reduced drying time under certain characteristic frequency of oscillations. The resultant deposit exhibits a much flatter structure with sharp, defined peripheral wedge topology as compared to natural drying. Such controlled manipulation of transport enables tailoring of structural and topological morphology of the deposits and offers possible routes towards controlling the formation and drying timescales which are crucial for applications ranging from pharmaceutics to surface patterning.

Airborne Precision Spacing: A Trajectory-based Approach to Improve Terminal Area Operations

NASA Technical Reports Server (NTRS)

Barmore, Bryan

2006-01-01

Airborne Precision Spacing has been developed by the National Aeronautics and Space Administration (NASA) over the past seven years as an attempt to benefit from the capabilities of the flight deck to precisely space their aircraft relative to another aircraft. This development has leveraged decades of work on improving terminal area operations, especially the arrival phase. With APS operations, the air traffic controller instructs the participating aircraft to achieve an assigned inter-arrival spacing interval at the runway threshold, relative to another aircraft. The flight crew then uses airborne automation to manage the aircraft s speed to achieve the goal. The spacing tool is designed to keep the speed within acceptable operational limits, promote system-wide stability, and meet the assigned goal. This reallocation of tasks with the controller issuing strategic goals and the flight crew managing the tactical achievement of those goals has been shown to be feasible through simulation and flight test. A precision of plus or minus 2-3 seconds is generally achievable. Simulations of long strings of arriving traffic show no signs of instabilities or compression waves. Subject pilots have rated the workload to be similar to current-day operations and eye-tracking data substantiate this result. This paper will present a high-level review of research results over the past seven years from a variety of tests and experiments. The results will focus on the precision and accuracy achievable, flow stability and some major sources of uncertainty. The paper also includes a summary of the flight crew s procedures and interface and a brief concept overview.

Quantitative passive soil vapor sampling for VOCs--Part 4: Flow-through cell.

PubMed

McAlary, Todd; Groenevelt, Hester; Seethapathy, Suresh; Sacco, Paolo; Crump, Derrick; Tuday, Michael; Schumacher, Brian; Hayes, Heidi; Johnson, Paul; Parker, Louise; Górecki, Tadeusz

2014-05-01

This paper presents a controlled experiment comparing several quantitative passive samplers for monitoring concentrations of volatile organic compound (VOC) vapors in soil gas using a flow-through cell. This application is simpler than conventional active sampling using adsorptive tubes because the flow rate does not need to be precisely measured and controlled, which is advantageous because the permeability of subsurface materials affects the flow rate and the permeability of geologic materials is highly variable. Using passive samplers in a flow-through cell, the flow rate may not need to be known exactly, as long as it is sufficient to purge the cell in a reasonable time and minimize any negative bias attributable to the starvation effect. An experiment was performed in a 500 mL flow-through cell using a two-factor, one-half fraction fractional factorial test design with flow rates of 80, 670 and 930 mL min(-1) and sample durations of 10, 15 and 20 minutes for each of five different passive samplers (passive Automatic Thermal Desorption Tube, Radiello®, SKC Ultra, Waterloo Membrane Sampler™ and 3M™ OVM 3500). A Summa canister was collected coincident with each passive sampler and analyzed by EPA Method TO-15 to provide a baseline for comparison of the passive sampler concentrations. The passive sampler concentrations were within a factor of 2 of the Summa canister concentrations in 32 of 35 cases. Passive samples collected at the low flow rate and short duration showed low concentrations, which is likely attributable to insufficient purging of the cell after sampler placement.

Spatial Manipulation of Heat Flow by Surface Boundaries at the Nanoscale

NASA Astrophysics Data System (ADS)

Malhotra, Abhinav; Maldovan, Martin

The precise manipulation of phonon transport properties is central to controlling thermal transport in semiconductor nanostructures. The physical understanding, prediction, and control of thermal phonon heat spectra and thermal conductivity accumulation functions - which establish the proportion of heat transported by phonons with different frequencies and mean-free-paths - has attracted significant attention in recent years. In this talk, we advance the possibilities of manipulating heat by spatially modulating thermal transport in nanostructures. We show that phonon scattering at interfaces impacts the most preferred physical pathway used by heat energy flow in thermal transport in nanostructures. The role of introducing boundaries with different surface conditions on resultant thermal flux is presented and methodologies to enhance these spatial modulations are discussed. This talk aims to advance the fundamental understanding on the nature of heat transport at nanoscale with potential applications in multiple research areas ranging from energy materials to optoelectronics.

LabVIEW-based control software for para-hydrogen induced polarization instrumentation.

PubMed

Agraz, Jose; Grunfeld, Alexander; Li, Debiao; Cunningham, Karl; Willey, Cindy; Pozos, Robert; Wagner, Shawn

2014-04-01

The elucidation of cell metabolic mechanisms is the modern underpinning of the diagnosis, treatment, and in some cases the prevention of disease. Para-Hydrogen induced polarization (PHIP) enhances magnetic resonance imaging (MRI) signals over 10,000 fold, allowing for the MRI of cell metabolic mechanisms. This signal enhancement is the result of hyperpolarizing endogenous substances used as contrast agents during imaging. PHIP instrumentation hyperpolarizes Carbon-13 ((13)C) based substances using a process requiring control of a number of factors: chemical reaction timing, gas flow, monitoring of a static magnetic field (Bo), radio frequency (RF) irradiation timing, reaction temperature, and gas pressures. Current PHIP instruments manually control the hyperpolarization process resulting in the lack of the precise control of factors listed above, resulting in non-reproducible results. We discuss the design and implementation of a LabVIEW based computer program that automatically and precisely controls the delivery and manipulation of gases and samples, monitoring gas pressures, environmental temperature, and RF sample irradiation. We show that the automated control over the hyperpolarization process results in the hyperpolarization of hydroxyethylpropionate. The implementation of this software provides the fast prototyping of PHIP instrumentation for the evaluation of a myriad of (13)C based endogenous contrast agents used in molecular imaging.

LabVIEW-based control software for para-hydrogen induced polarization instrumentation

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

Agraz, Jose, E-mail: joseagraz@ucla.edu; Grunfeld, Alexander; Li, Debiao

2014-04-15

The elucidation of cell metabolic mechanisms is the modern underpinning of the diagnosis, treatment, and in some cases the prevention of disease. Para-Hydrogen induced polarization (PHIP) enhances magnetic resonance imaging (MRI) signals over 10 000 fold, allowing for the MRI of cell metabolic mechanisms. This signal enhancement is the result of hyperpolarizing endogenous substances used as contrast agents during imaging. PHIP instrumentation hyperpolarizes Carbon-13 ({sup 13}C) based substances using a process requiring control of a number of factors: chemical reaction timing, gas flow, monitoring of a static magnetic field (B{sub o}), radio frequency (RF) irradiation timing, reaction temperature, and gas pressures.more » Current PHIP instruments manually control the hyperpolarization process resulting in the lack of the precise control of factors listed above, resulting in non-reproducible results. We discuss the design and implementation of a LabVIEW based computer program that automatically and precisely controls the delivery and manipulation of gases and samples, monitoring gas pressures, environmental temperature, and RF sample irradiation. We show that the automated control over the hyperpolarization process results in the hyperpolarization of hydroxyethylpropionate. The implementation of this software provides the fast prototyping of PHIP instrumentation for the evaluation of a myriad of {sup 13}C based endogenous contrast agents used in molecular imaging.« less

Multiphase flow microfluidics for the production of single or multiple emulsions for drug delivery.

PubMed

Zhao, Chun-Xia

2013-11-01

Considerable effort has been directed towards developing novel drug delivery systems. Microfluidics, capable of generating monodisperse single and multiple emulsion droplets, executing precise control and operations on these droplets, is a powerful tool for fabricating complex systems (microparticles, microcapsules, microgels) with uniform size, narrow size distribution and desired properties, which have great potential in drug delivery applications. This review presents an overview of the state-of-the-art multiphase flow microfluidics for the production of single emulsions or multiple emulsions for drug delivery. The review starts with a brief introduction of the approaches for making single and multiple emulsions, followed by presentation of some potential drug delivery systems (microparticles, microcapsules and microgels) fabricated in microfluidic devices using single or multiple emulsions as templates. The design principles, manufacturing processes and properties of these drug delivery systems are also discussed and compared. Furthermore, drug encapsulation and drug release (including passive and active controlled release) are provided and compared highlighting some key findings and insights. Finally, site-targeting delivery using multiphase flow microfluidics is also briefly introduced. Copyright © 2013 Elsevier B.V. All rights reserved.

Numerical simulation of polishing U-tube based on solid-liquid two-phase

NASA Astrophysics Data System (ADS)

Li, Jun-ye; Meng, Wen-qing; Wu, Gui-ling; Hu, Jing-lei; Wang, Bao-zuo

2018-03-01

As the advanced technology to solve the ultra-precision machining of small hole structure parts and complex cavity parts, the abrasive grain flow processing technology has the characteristics of high efficiency, high quality and low cost. So this technology in many areas of precision machining has an important role. Based on the theory of solid-liquid two-phase flow coupling, a solid-liquid two-phase MIXTURE model is used to simulate the abrasive flow polishing process on the inner surface of U-tube, and the temperature, turbulent viscosity and turbulent dissipation rate in the process of abrasive flow machining of U-tube were compared and analyzed under different inlet pressure. In this paper, the influence of different inlet pressure on the surface quality of the workpiece during abrasive flow machining is studied and discussed, which provides a theoretical basis for the research of abrasive flow machining process.

Respiratory mechanics by least squares fitting in mechanically ventilated patients: application on flow-limited COPD patients.

PubMed

Volta, Carlo A; Marangoni, Elisabetta; Alvisi, Valentina; Capuzzo, Maurizia; Ragazzi, Riccardo; Pavanelli, Lina; Alvisi, Raffaele

2002-01-01

Although computerized methods of analyzing respiratory system mechanics such as the least squares fitting method have been used in various patient populations, no conclusive data are available in patients with chronic obstructive pulmonary disease (COPD), probably because they may develop expiratory flow limitation (EFL). This suggests that respiratory mechanics be determined only during inspiration. Eight-bed multidisciplinary ICU of a teaching hospital. Eight non-flow-limited postvascular surgery patients and eight flow-limited COPD patients. Patients were sedated, paralyzed for diagnostic purposes, and ventilated in volume control ventilation with constant inspiratory flow rate. Data on resistance, compliance, and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn) obtained by applying the least squares fitting method during inspiration, expiration, and the overall breathing cycle were compared with those obtained by the traditional method (constant flow, end-inspiratory occlusion method). Our results indicate that (a) the presence of EFL markedly decreases the precision of resistance and compliance values measured by the LSF method, (b) the determination of respiratory variables during inspiration allows the calculation of respiratory mechanics in flow limited COPD patients, and (c) the LSF method is able to detect the presence of PEEPi,dyn if only inspiratory data are used.

Experimental and Computational Investigation of Microbubble Production in Microfluidic Flow-Focusing Devices

NASA Astrophysics Data System (ADS)

Weber, Michael; Shandas, Robin

2005-11-01

Micron-sized bubbles have been effectively used as contrast agents in ultrasound imaging systems and have the potential for many other applications including targeted drug delivery and tumor destruction. The further development of these applications is dependent on precise control of bubble size. Recently, microfluidic flow-focusing systems have emerged as a viable means of producing microbubbles with monodisperse size distributions. These systems focus co-flowing liquid streams surrounding a gas stream through a narrow orifice, producing bubbles in very reproducible manner. In this work, a photopolymerization technique has been used to produce microfludicic flow-focusing devices which were successfully used to produce micron-sized bubbles. The flow dynamics involved in these devices has also been simulated using a volume-of-fluid approach to simultaneously solve the equations of motion for both the gas and liquid phases. Simulations were run with several variations of the flow-focuser geometry (gas inlet width, orifice length, gas-liquid approach angle, etc.) in an effort to produce smaller bubbles and increase the working range of liquid and gas flow rates. These findings are being incorporated into the production of actual devices in an effort to improve the overall effectiveness of the bubble production process.

A quantified dosing ALD reactor with in-situ diagnostics for surface chemistry studies

NASA Astrophysics Data System (ADS)

Larrabee, Thomas J.

A specialized atomic layer deposition (ALD) reactor has been constructed to serve as an instrument to simultaneously study the surface chemistry of the ALD process, and perform ALD as is conventionally done in continuum flow of inert gas. This reactor is uniquely useful to gain insight into the ALD process because of the combination of its precise, controllable, and quantified dosing/microdosing capability; its in-situ quadrupole mass spectrometer for gas composition analysis; its pair of highly-sensitive in-situ quartz crystal microbalances (QCMs); and its complete spectrum of pressures and operating conditions --- from viscous to molecular flow regimes. Control of the dose is achieved independently of the conditions by allowing a reactant gas to fill a fixed volume and measured pressure, which is held at a controlled temperature, and subsequently dosed into the system by computer controlled pneumatic valves. Absolute reactant exposure to the substrate and QCMs is unambiguously calculated from the molecular impingement flux, and its relationship to dose size is established, allowing means for easily intentionally reproducing specific exposures. Methods for understanding atomic layer growth and adsorption phenomena, including the precursor sticking probability, dynamics of molecular impingement, size of dose, and other operating variables are for the first time quantitatively related to surface reaction rates by mass balance. Extensive characterization of the QCM as a measurement tool for adsorption under realistic ALD conditions has been examined, emphasizing the state-of-the-art and importance of QCM system features required. Finally, the importance of dose-quantification and microdosing has been contextualized in view of the ALD literature, underscoring the significance of more precise condition specification in establishing a better basis for reactor and reactant comparison.

Laser Doppler imaging of cutaneous blood flow through transparent face masks: a necessary preamble to computer-controlled rapid prototyping fabrication with submillimeter precision.

PubMed

Allely, Rebekah R; Van-Buendia, Lan B; Jeng, James C; White, Patricia; Wu, Jingshu; Niszczak, Jonathan; Jordan, Marion H

2008-01-01

A paradigm shift in management of postburn facial scarring is lurking "just beneath the waves" with the widespread availability of two recent technologies: precise three-dimensional scanning/digitizing of complex surfaces and computer-controlled rapid prototyping three-dimensional "printers". Laser Doppler imaging may be the sensible method to track the scar hyperemia that should form the basis of assessing progress and directing incremental changes in the digitized topographical face mask "prescription". The purpose of this study was to establish feasibility of detecting perfusion through transparent face masks using the Laser Doppler Imaging scanner. Laser Doppler images of perfusion were obtained at multiple facial regions on five uninjured staff members. Images were obtained without a mask, followed by images with a loose fitting mask with and without a silicone liner, and then with a tight fitting mask with and without a silicone liner. Right and left oblique images, in addition to the frontal images, were used to overcome unobtainable measurements at the extremes of face mask curvature. General linear model, mixed model, and t tests were used for data analysis. Three hundred seventy-five measurements were used for analysis, with a mean perfusion unit of 299 and pixel validity of 97%. The effect of face mask pressure with and without the silicone liner was readily quantified with significant changes in mean cutaneous blood flow (P < .5). High valid pixel rate laser Doppler imager flow data can be obtained through transparent face masks. Perfusion decreases with the application of pressure and with silicone. Every participant measured differently in perfusion units; however, consistent perfusion patterns in the face were observed.

Dynamically formed admicelle layer to control the amplitude of cathodic electroosmotic flow.

PubMed

Erny, Guillaume L; Gonçalves, Bruna M; Esteves, Valdemar I

2012-09-21

In this manuscript, a method to precisely adjust the amplitude of a cathodic electroosmotic flow is described. The method uses a capillary pre-coated with a cationic polymer (polybrene), in presence of an anionic surfactant such as sodium dodecyl sulfate. At low concentration of surfactant, molecules will self-assemble to form an immobilized hemimicelle layer with the anionic "head" in contact with the cationic coating and the hydrophobic tail reaching into the background electrolyte. At higher concentration, surfactant molecules in solution will then interact, via hydrophobic interactions, to form an admicelle layer. It has been demonstrated that the admicelle layer can be constructed with either pure anionic surfactant (SDS), or a mixture of anionic and neutral surfactants. Admicelle coatings can be used to control the electroosmotic flow (EOF). While at low surfactant concentration the amplitude of the EOF depends on the concentration of the surfactants concentration, when this concentration reaches the critical admicelle concentration the EOF becomes near constant. The amplitude of the EOF can also be adjusted via the relative proportion of neutral and ionic surfactant in solution. Using this approach, the EOF was varied from 0.450 to 3.848 × 10(-8)m(2)V(-1)s(-1) with a precision below 0.050 × 10(-8)m(2)V(-1)s(-1) (standard deviation measured with three replicates). The coating has been tested using a mix of triazines (atrazine, simazine and terbuthylazine) and a beer sample. With the beer sample an average relative standard deviation of 1.5% for the migration time and of 2.2% for the corrected peak area was obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

Robust post-stall perching with a simple fixed-wing glider using LQR-Trees.

PubMed

Moore, Joseph; Cory, Rick; Tedrake, Russ

2014-06-01

Birds routinely execute post-stall maneuvers with a speed and precision far beyond the capabilities of our best aircraft control systems. One remarkable example is a bird exploiting post-stall pressure drag in order to rapidly decelerate to land on a perch. Stall is typically associated with a loss of control authority, and it is tempting to attribute this agility of birds to the intricate morphology of the wings and tail, to their precision sensing apparatus, or their ability to perform thrust vectoring. Here we ask whether an extremely simple fixed-wing glider (no propeller) with only a single actuator in the tail is capable of landing precisely on a perch from a large range of initial conditions. To answer this question, we focus on the design of the flight control system; building upon previous work which used linear feedback control design based on quadratic regulators (LQR), we develop nonlinear feedback control based on nonlinear model-predictive control and 'LQR-Trees'. Through simulation using a flat-plate model of the glider, we find that both nonlinear methods are capable of achieving an accurate bird-like perching maneuver from a large range of initial conditions; the 'LQR-Trees' algorithm is particularly useful due to its low computational burden at runtime and its inherent performance guarantees. With this in mind, we then implement the 'LQR-Trees' algorithm on real hardware and demonstrate a 95 percent perching success rate over 147 flights for a wide range of initial speeds. These results suggest that, at least in the absence of significant disturbances like wind gusts, complex wing morphology and sensing are not strictly required to achieve accurate and robust perching even in the post-stall flow regime.

Treatment of High Flow Arteriovenous Fistulas after Successful Renal Transplant Using a Simple Precision Banding Technique.

PubMed

Gkotsis, Georgios; Jennings, William C; Malik, Jan; Mallios, Alexandros; Taubman, Kevin

2016-02-01

Observation versus ligation of a functional arteriovenous fistula (AVF) after successful renal transplantation (SRT) has been a controversial topic of debate. Congestive heart failure and pulmonary hypertension are common in dialysis patients, and more frequent when vascular access flow is excessive. Renal transplant failure may occur in up to 34% of patients after 5 years, therefore maintaining a moderate flow AVF appears warranted. We review SRT patients with high flow-AVFs (HF-AVF) and clinical signs of heart failure where a modified precision banding procedure was used for access flow reduction. Patients referred for HF-AVF evaluation after SRT were identified and records reviewed retrospectively. In addition to recording clinical signs of heart failure, each patient had ultrasound AVF flow measurement before and after temporary AVF occlusion of the access by digital compression. Pulse rate and the presence or absence of a cardiac murmur was noted before and after AVF compression. Adequacy of access flow restriction was evaluated intraoperatively using ultrasound flow measurements, adjusting the banding diameter in 0.5 mm increments to achieve the targeted AVF flow. Twelve patients were evaluated over a 19-month period. Eight (66%) were male and one (8%) obese. Ages were 15-73 years (mean = 42). The AVFs were established 24-86 months previously. The mean pulse rate declined after AVF compression from 90/min to 72/min (range 110-78). Six patients had a precompression cardiac flow murmur that disappeared with temporary AVF compression. One patient with poor cardiac function underwent immediate AVF ligation with dramatic improvement in cardiac status. All other patients underwent a precision banding procedure with real-time flow monitoring. Mean access flow was 2,280 mL/min (1,148-3,320 mL/min) before access banding and was 598 mL/min (481-876) after flow reduction. The clinical signs of heart failure disappeared in all patients. All AVFs remained patent although one individual later requested ligation for cosmesis. Two patients had renal transplant failure and later successfully used the AVF. Follow-up postbanding was 1-18 months (mean = 12). Patients with successful renal transplants and HF-AVFs had resolution of heart failure findings and maintenance of access patency using a modified precision banding procedure. Flow reduction in symptomatic renal transplant patients with elevated access flow is recommended. Further study is warranted to substantiate these recommendations and clarify the appropriate thresholds for such interventions. Copyright © 2016 Elsevier Inc. All rights reserved.

Discrete adjoint of fractional step Navier-Stokes solver in generalized coordinates

NASA Astrophysics Data System (ADS)

Wang, Mengze; Mons, Vincent; Zaki, Tamer

2017-11-01

Optimization and control in transitional and turbulent flows require evaluation of gradients of the flow state with respect to the problem parameters. Using adjoint approaches, these high-dimensional gradients can be evaluated with a similar computational cost as the forward Navier-Stokes simulations. The adjoint algorithm can be obtained by discretizing the continuous adjoint Navier-Stokes equations or by deriving the adjoint to the discretized Navier-Stokes equations directly. The latter algorithm is necessary when the forward-adjoint relations must be satisfied to machine precision. In this work, our forward model is the fractional step solution to the Navier-Stokes equations in generalized coordinates, proposed by Rosenfeld, Kwak & Vinokur. We derive the corresponding discrete adjoint equations. We also demonstrate the accuracy of the combined forward-adjoint model, and its application to unsteady wall-bounded flows. This work has been partially funded by the Office of Naval Research (Grant N00014-16-1-2542).

Flow cytometry as a tool for analyzing changes in Plasmodium falciparum cell cycle following treatment with indol compounds.

PubMed

Schuck, Desirée Cigaran; Ribeiro, Ramira Yuri; Nery, Arthur A; Ulrich, Henning; Garcia, Célia R S

2011-11-01

Melatonin and its derivatives modulate the Plasmodium falciparum and Plasmodium chabaudi cell cycle. Flow cytometry was employed together with the nucleic acid dye YOYO-1 allowing precise discrimination between mono- and multinucleated forms of P. falciparum-infected red blood cell. The use of YOYO-1 permitted excellent discrimination between uninfected and infected red blood cells as well as between early and late parasite stages. Fluorescence intensities of schizont-stage parasites were about 10-fold greater than those of ring-trophozoite form parasites. Melatonin and related indolic compounds including serotonin, N-acetyl-serotonin and tryptamine induced an increase in the percentage of multinucleated forms compared to non-treated control cultures. YOYO-1 staining of infected erythrocyte and subsequent flow cytometry analysis provides a powerful tool in malaria research for screening of bioactive compounds. Copyright © 2011 International Society for Advancement of Cytometry.

Cell-flow technique.

PubMed

Hess, George P; Lewis, Ryan W; Chen, Yongli

2014-10-01

Various devices have been used to flow neurotransmitter solutions over cells containing receptors (e.g., ligand-gated ion channels) for whole-cell current recordings. With many of the devices, the orientation between the porthole of the flow device and the cell is not maintained absolutely constant. Orientation is critical for reproducibility in kinetic experiments. To be able to change the composition of the flowing solution during an experiment and still maintain a constant orientation, we use the cell-flow device described here. A peristaltic pump, a stainless steel U-tube, two different sizes of peristaltic tubing, and a solenoid valve are required to create a simple solution exchange system that can rapidly apply and remove solutions over the surface of a cell in tens of milliseconds. This system allows one to test multiple conditions on a cell containing the receptor of interest while constantly "washing" the cell with extracellular buffer solution between experimental applications. The use of the solenoid valve allows for the application of solutions to be precisely timed and controlled by a computer during electrophysiological current recording. © 2014 Cold Spring Harbor Laboratory Press.

Amplatzer vascular plug as an embolic agent in different vascular pathologies: A pictorial essay

PubMed Central

Tresley, Jonathan; Bhatia, Shivank; Kably, Issam; Poozhikunnath Mohan, Prasoon; Salsamendi, Jason; Narayanan, Govindarajan

2016-01-01

The Amplatzer Vascular Plug (AVP) is a cylindrical plug made of self-expanding nitinol wire mesh with precise delivery control, which can be used for a variety of vascular pathologies. An AVP is an ideal vascular occlusion device particularly in high-flow vessels, where there is high risk of migration and systemic embolization with traditional occlusion devices. We performed 28 embolizations using the AVP from 2009 to 2014 and achieved complete occlusion without complications. PMID:27413276

Continuing Experiments on the Receptivity of Transient Disturbances to Surface Roughness and Freestream Turbulence

DTIC Science & Technology

2008-09-28

rotating the spindle of the angle controller with a precision of 0.2°. The multiple-hotwire holder is designed to carry four hotwires. One hotwire is a...section and a maximum operating speed of 25 m/s. The tunnel’s design follows the recommendations of Reshotko et al. (1997) for flow quality. Operating at...This sting assembly includes a shaft that rotates in a streamlined casing and allows angular calibration of slanted hotwires. Outside the test

Very high precision and accuracy analysis of triple isotopic ratios of water. A critical instrumentation comparison study.

NASA Astrophysics Data System (ADS)

Gkinis, Vasileios; Holme, Christian; Morris, Valerie; Thayer, Abigail Grace; Vaughn, Bruce; Kjaer, Helle Astrid; Vallelonga, Paul; Simonsen, Marius; Jensen, Camilla Marie; Svensson, Anders; Maffrezzoli, Niccolo; Vinther, Bo; Dallmayr, Remi

2017-04-01

We present a performance comparison study between two state of the art Cavity Ring Down Spectrometers (Picarro L2310-i, L2140-i). The comparison took place during the Continuous Flow Analysis (CFA) campaign for the measurement of the Renland ice core, over a period of three months. Instant and complete vaporisation of the ice core melt stream, as well as of in-house water reference materials is achieved by accurate control of microflows of liquid into a homemade calibration system by following simple principles of the Hagen-Poiseuille law. Both instruments share the same vaporisation unit in a configuration that minimises sample preparation discrepancies between the two analyses. We describe our SMOW-SLAP calibration and measurement protocols for such a CFA application and present quality control metrics acquired during the full period of the campaign on a daily basis. The results indicate an unprecedented performance for all 3 isotopic ratios (δ2H, δ17O, δ18O ) in terms of precision, accuracy and resolution. We also comment on the precision and accuracy of the second order excess parameters of HD16O and H217O over H218O (Dxs, Δ17O ). To our knowledge these are the first reported CFA measurements at this level of precision and accuracy for all three isotopic ratios. Differences on the performance of the two instruments are carefully assessed during the measurement and reported here. Our quality control protocols extend to the area of low water mixing ratios, a regime in which often atmospheric vapour measurements take place and Cavity Ring Down Analysers show a poorer performance due to the lower signal to noise ratios. We address such issues and propose calibration protocols from which water vapour isotopic analyses can benefit from.

Simple Perfusion Apparatus (SPA) for Manipulation, Tracking and Study of Oocytes and Embryos

PubMed Central

Angione, Stephanie L.; Oulhen, Nathalie; Brayboy, Lynae M.; Tripathi, Anubhav; Wessel, Gary M.

2016-01-01

Objective To develop and implement a device and protocol for oocyte analysis at a single cell level. The device must be capable of high resolution imaging, temperature control, perfusion of media, drugs, sperm, and immunolabeling reagents all at defined flow-rates. Each oocyte and resultant embryo must remain spatially separated and defined. Design Experimental laboratory study Setting University and Academic Center for reproductive medicine. Patients/Animals Women with eggs retrieved for ICSI cycles, adult female FVBN and B6C3F1 mouse strains, sea stars. Intervention Real-time, longitudinal imaging of oocytes following fluorescent labeling, insemination, and viability tests. Main outcome measure(s) Cell and embryo viability, immunolabeling efficiency, live cell endocytosis quantitation, precise metrics of fertilization and embryonic development. Results Single oocytes were longitudinally imaged following significant changes in media, markers, endocytosis quantitation, and development, all with supreme control by microfluidics. Cells remained viable, enclosed, and separate for precision measurements, repeatability, and imaging. Conclusions We engineered a simple device to load, visualize, experiment, and effectively record individual oocytes and embryos, without loss of cells. Prolonged incubation capabilities provide longitudinal studies without need for transfer and potential loss of cells. This simple perfusion apparatus (SPA) provides for careful, precise, and flexible handling of precious samples facilitating clinical in vitro fertilization approaches. PMID:25450296

High-performance holographic technologies for fluid-dynamics experiments

PubMed Central

Orlov, Sergei S.; Abarzhi, Snezhana I.; Oh, Se Baek; Barbastathis, George; Sreenivasan, Katepalli R.

2010-01-01

Modern technologies offer new opportunities for experimentalists in a variety of research areas of fluid dynamics. Improvements are now possible in the state-of-the-art in precision, dynamic range, reproducibility, motion-control accuracy, data-acquisition rate and information capacity. These improvements are required for understanding complex turbulent flows under realistic conditions, and for allowing unambiguous comparisons to be made with new theoretical approaches and large-scale numerical simulations. One of the new technologies is high-performance digital holography. State-of-the-art motion control, electronics and optical imaging allow for the realization of turbulent flows with very high Reynolds number (more than 107) on a relatively small laboratory scale, and quantification of their properties with high space–time resolutions and bandwidth. In-line digital holographic technology can provide complete three-dimensional mapping of the flow velocity and density fields at high data rates (over 1000 frames per second) over a relatively large spatial area with high spatial (1–10 μm) and temporal (better than a few nanoseconds) resolution, and can give accurate quantitative description of the fluid flows, including those of multi-phase and unsteady conditions. This technology can be applied in a variety of problems to study fundamental properties of flow–particle interactions, rotating flows, non-canonical boundary layers and Rayleigh–Taylor mixing. Some of these examples are discussed briefly. PMID:20211881

Theory and applications survey of decentralized control methods

NASA Technical Reports Server (NTRS)

Athans, M.

1975-01-01

A nonmathematical overview is presented of trends in the general area of decentralized control strategies which are suitable for hierarchical systems. Advances in decentralized system theory are closely related to advances in the so-called stochastic control problem with nonclassical information pattern. The basic assumptions and mathematical tools pertaining to the classical stochastic control problem are outlined. Particular attention is devoted to pitfalls in the mathematical problem formulation for decentralized control. Major conclusions are that any purely deterministic approach to multilevel hierarchical dynamic systems is unlikely to lead to realistic theories or designs, that the flow of measurements and decisions in a decentralized system should not be instantaneous and error-free, and that delays in information exchange in a decentralized system lead to reasonable approaches to decentralized control. A mathematically precise notion of aggregating information is not yet available.

Preservation of renal blood flow by the antioxidant EUK-134 in LPS-treated pigs.

PubMed

Magder, Sheldon; Parthenis, Dimitrios G; Ghouleh, Imad Al

2015-03-25

Sepsis is associated with an increase in reactive oxygen species (ROS), however, the precise role of ROS in the septic process remains unknown. We hypothesized that treatment with EUK-134 (manganese-3-methoxy N,N'-bis(salicyclidene)ethylene-diamine chloride), a compound with superoxide dismutase and catalase activity, attenuates the vascular manifestations of sepsis in vivo. Pigs were instrumented to measure cardiac output and blood flow in renal, superior mesenteric and femoral arteries, and portal vein. Animals were treated with saline (control), lipopolysaccharide (LPS; 10 µg·kg-1·h-1), EUK-134, or EUK-134 plus LPS. Results show that an LPS-induced increase in pulmonary artery pressure (PAP) as well as a trend towards lower blood pressure (BP) were both attenuated by EUK-134. Renal blood flow decreased with LPS whereas superior mesenteric, portal and femoral flows did not change. Importantly, EUK-134 decreased the LPS-induced fall in renal blood flow and this was associated with a corresponding decrease in LPS-induced protein nitrotyrosinylation in the kidney. PO2, pH, base excess and systemic vascular resistance fell with LPS and were unaltered by EUK-134. EUK-134 also had no effect on LPS-associated increase in CO. Interestingly, EUK-134 alone resulted in higher CO, BP, PAP, mean circulatory filling pressure, and portal flow than controls. Taken together, these data support a protective role for EUK-134 in the renal circulation in sepsis.

Myocardial blood flow quantification by Rb-82 cardiac PET/CT: A detailed reproducibility study between two semi-automatic analysis programs.

PubMed

Dunet, Vincent; Klein, Ran; Allenbach, Gilles; Renaud, Jennifer; deKemp, Robert A; Prior, John O

2016-06-01

Several analysis software packages for myocardial blood flow (MBF) quantification from cardiac PET studies exist, but they have not been compared using concordance analysis, which can characterize precision and bias separately. Reproducible measurements are needed for quantification to fully develop its clinical potential. Fifty-one patients underwent dynamic Rb-82 PET at rest and during adenosine stress. Data were processed with PMOD and FlowQuant (Lortie model). MBF and myocardial flow reserve (MFR) polar maps were quantified and analyzed using a 17-segment model. Comparisons used Pearson's correlation ρ (measuring precision), Bland and Altman limit-of-agreement and Lin's concordance correlation ρc = ρ·C b (C b measuring systematic bias). Lin's concordance and Pearson's correlation values were very similar, suggesting no systematic bias between software packages with an excellent precision ρ for MBF (ρ = 0.97, ρc = 0.96, C b = 0.99) and good precision for MFR (ρ = 0.83, ρc = 0.76, C b = 0.92). On a per-segment basis, no mean bias was observed on Bland-Altman plots, although PMOD provided slightly higher values than FlowQuant at higher MBF and MFR values (P < .0001). Concordance between software packages was excellent for MBF and MFR, despite higher values by PMOD at higher MBF values. Both software packages can be used interchangeably for quantification in daily practice of Rb-82 cardiac PET.

Immersed Boundary Models for Quantifying Flow-Induced Mechanical Stimuli on Stem Cells Seeded on 3D Scaffolds in Perfusion Bioreactors.

PubMed

Guyot, Yann; Smeets, Bart; Odenthal, Tim; Subramani, Ramesh; Luyten, Frank P; Ramon, Herman; Papantoniou, Ioannis; Geris, Liesbet

2016-09-01

Perfusion bioreactors regulate flow conditions in order to provide cells with oxygen, nutrients and flow-associated mechanical stimuli. Locally, these flow conditions can vary depending on the scaffold geometry, cellular confluency and amount of extra cellular matrix deposition. In this study, a novel application of the immersed boundary method was introduced in order to represent a detailed deformable cell attached to a 3D scaffold inside a perfusion bioreactor and exposed to microscopic flow. The immersed boundary model permits the prediction of mechanical effects of the local flow conditions on the cell. Incorporating stiffness values measured with atomic force microscopy and micro-flow boundary conditions obtained from computational fluid dynamics simulations on the entire scaffold, we compared cell deformation, cortical tension, normal and shear pressure between different cell shapes and locations. We observed a large effect of the precise cell location on the local shear stress and we predicted flow-induced cortical tensions in the order of 5 pN/μm, at the lower end of the range reported in literature. The proposed method provides an interesting tool to study perfusion bioreactors processes down to the level of the individual cell's micro-environment, which can further aid in the achievement of robust bioprocess control for regenerative medicine applications.

In microfluidico: Recreating in vivo hemodynamics using miniaturized devices

PubMed Central

Zhu, Shu; Herbig, Bradley A.; Li, Ruizhi; Colace, Thomas V.; Muthard, Ryan W.; Neeves, Keith B.; Diamond, Scott L.

2016-01-01

Microfluidic devices create precisely controlled reactive blood flows and typically involve: (i) validated anticoagulation/pharmacology protocols, (ii) defined reactive surfaces, (iii) defined flow-transport regimes, and (iv) optical imaging. An 8-channel device can be run at constant flow rate or constant pressure drop for blood perfusion over a patterned collagen, collagen/kaolin, or collagen/tissue factor (TF) to measure platelet, thrombin, and fibrin dynamics during clot growth. A membrane-flow device delivers a constant flux of platelet agonists or coagulation enzymes into flowing blood. A trifurcated device sheaths a central blood flow on both sides with buffer, an ideal approach for on-chip recalcification of citrated blood or drug delivery. A side-view device allows clotting on a porous collagen/TF plug at constant pressure differential across the developing clot. The core-shell architecture of clots made in mouse models can be replicated in this device using human blood. For pathological flows, a stenosis device achieves shear rates of >100,000 s−1 to drive plasma von Willebrand factor (VWF) to form thick long fibers on collagen. Similarly, a micropost-impingement device creates extreme elongational and shear flows for VWF fiber formation without collagen. Overall, microfluidics are ideal for studies of clotting, bleeding, fibrin polymerization/fibrinolysis, cell/clot mechanics, adhesion, mechanobiology, and reaction-transport dynamics. PMID:26600269

Free-surface microfluidics for detection of airborne explosives

NASA Astrophysics Data System (ADS)

Meinhart, Carl; Piorek, Brian; Banerjee, Sanjoy; Lee, Seung Joon; Moskovits, Martin

2008-11-01

A novel microfluidic, remote-sensing, chemical detection platform has been developed for real-time sensing of airborne agents. The key enabling technology is a newly developed concept termed Free-Surface Fluidics (FSF), where one or more fluidic surfaces of a microchannel flow are confined by surface tension and exposed to the surrounding atmosphere. The result is a unique open channel flow environment that is driven by pressure through surface tension, and not subject to body forces, such as gravity. Evaporation and flow rates are controlled by microchannel geometry, surface chemistry and precisely-controlled temperature profiles. The free-surface fluidic architecture is combined with Surface-Enhanced Raman Spectroscopy (SERS) to allow for real-time profiling of atmospheric species and detection of airborne agents. The aggregation of SERS nanoparticles is controlled using microfluidics, to obtain dimer nanoparticle clusters at known streamwise positions in the microchannel. These dimers form SERS hot-spots, which amplify the Raman signal by 8 -- 10 orders of magnitude. Results indicate that explosive agents such as DNT, TNT, RDX, TATP and picric acid in the surrounding atmosphere can be readily detected by the SERS system. Due to the amplification of the SERS system, explosive molecules with concentrations of parts per trillion can be detected, even in the presence of interferent molecules having six orders of magnitude higher concentration.

Confocal Microscopy and Flow Cytometry System Performance: Assessment of QA Parameters that affect data Quanitification

EPA Science Inventory

Flow and image cytometers can provide useful quantitative fluorescence data. We have devised QA tests to be used on both a flow cytometer and a confocal microscope to assure that the data is accurate, reproducible and precise. Flow Cytometry: We have provided two simple perform...

Design and Fabrication of a MEMS Flow Sensor and Its Application in Precise Liquid Dispensing

PubMed Central

Liu, Yaxin; Chen, Liguo; Sun, Lining

2009-01-01

A high speed MEMS flow sensor to enhance the reliability and accuracy of a liquid dispensing system is proposed. Benefitting from the sensor information feedback, the system can self-adjust the open time of the solenoid valve to accurately dispense desired volumes of reagent without any pre-calibration. First, an integrated high-speed liquid flow sensor based on the measurement of the pressure difference across a flow channel is presented. Dimensions of the micro-flow channel and two pressure sensors have been appropriately designed to meet the static and dynamic requirements of the liquid dispensing system. Experiments results show that the full scale (FS) flow measurement ranges up to 80 μL/s, with a nonlinearity better than 0.51% FS. Secondly, a novel closed-loop control strategy is proposed to calculate the valve open time in each dispensing cycle, which makes the system immune to liquid viscosity, pressure fluctuation, and other sources of error. Finally, dispensing results show that the system can achieve better dispensing performance, and the coefficient of variance (CV) for liquid dispensing is below 3% at 1 μL and below 4% at 100 nL. PMID:22408517

Design and Fabrication of a MEMS Flow Sensor and Its Application in Precise Liquid Dispensing.

PubMed

Liu, Yaxin; Chen, Liguo; Sun, Lining

2009-01-01

A high speed MEMS flow sensor to enhance the reliability and accuracy of a liquid dispensing system is proposed. Benefitting from the sensor information feedback, the system can self-adjust the open time of the solenoid valve to accurately dispense desired volumes of reagent without any pre-calibration. First, an integrated high-speed liquid flow sensor based on the measurement of the pressure difference across a flow channel is presented. Dimensions of the micro-flow channel and two pressure sensors have been appropriately designed to meet the static and dynamic requirements of the liquid dispensing system. Experiments results show that the full scale (FS) flow measurement ranges up to 80 μL/s, with a nonlinearity better than 0.51% FS. Secondly, a novel closed-loop control strategy is proposed to calculate the valve open time in each dispensing cycle, which makes the system immune to liquid viscosity, pressure fluctuation, and other sources of error. Finally, dispensing results show that the system can achieve better dispensing performance, and the coefficient of variance (CV) for liquid dispensing is below 3% at 1 μL and below 4% at 100 nL.

Two-Dimensional Automatic Measurement for Nozzle Flow Distribution Using Improved Ultrasonic Sensor

PubMed Central

Zhai, Changyuan; Zhao, Chunjiang; Wang, Xiu; Wang, Ning; Zou, Wei; Li, Wei

2015-01-01

Spray deposition and distribution are affected by many factors, one of which is nozzle flow distribution. A two-dimensional automatic measurement system, which consisted of a conveying unit, a system control unit, an ultrasonic sensor, and a deposition collecting dish, was designed and developed. The system could precisely move an ultrasonic sensor above a pesticide deposition collecting dish to measure the nozzle flow distribution. A sensor sleeve with a PVC tube was designed for the ultrasonic sensor to limit its beam angle in order to measure the liquid level in the small troughs. System performance tests were conducted to verify the designed functions and measurement accuracy. A commercial spray nozzle was also used to measure its flow distribution. The test results showed that the relative error on volume measurement was less than 7.27% when the liquid volume was 2 mL in trough, while the error was less than 4.52% when the liquid volume was 4 mL or more. The developed system was also used to evaluate the flow distribution of a commercial nozzle. It was able to provide the shape and the spraying width of the flow distribution accurately. PMID:26501288

A COMPREHENSIVE STUDY OF HOURLY AND DAILY SEWAGE FLOW RATES IN FLORIDA PUBLIC SCHOOLS.

ERIC Educational Resources Information Center

FOGARTY, WILLIAM J.; REEDER, MILTON E.

A DETERMINATION OF THE HOURLY AND DAILY SEWAGE FLOW RATES IN FLORIDA PUBLIC SCHOOLS WAS MADE TO IDENTIFY THE FLOW CHARACTERISTICS AND TO PROVIDE A MORE PRECISE BASIS FOR THE ESTABLISHMENT OF DESIGN CRITERIA FOR SEWAGE DISPOSAL FACILITIES IN SCHOOLS. WATER FLOW DATA WAS COLLECTED FOR 158 SCHOOLS AND SEWAGE FLOW DATA FROM 42 SCHOOLS. THE FINDINGS…

Evaluation of four fast-response flow measurement devices

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

Gero, A.J.; Suppers, K.L.; Tomb, T.F.

1988-01-01

The Federal Mine Safety and Health Act of 1977 requires that sampling of dust in coal mine environments be conducted with an approved sampler operating at a flow rate of 2.0 liters of air per minute or at such other flow rate as prescribed by the Secretaries of Labor and of Health and Human Services. Standard procedures for calibration of these samplers within the Mine Safety and Health Administration utilize either a 3.0 liter capacity wet test meter or a 1.0 liter soap film calibrator. Several new flow calibrating devices have become commercially available. This paper describes an evaluation conductedmore » on four such devices: the Mast Model 823-2 bubble flowmeter, the Buck Calibrator, the Kurz Model 541S mass flowmeter and the Kurz Pocket Calibrator. The precision of a series of measurements made with each instrument was compared to the precision of a series of measurements made with the wet test meter. The comparison showed that the variability of calibration measurements obtained with the fast response flow calibrators was between 1.5 and 4.5 times larger than that obtained with the WTM; however, with all of the calibration devices evaluated, three repetitive measurements were sufficient to obtain a precision of {plus minus}0.1 liters per minute. 4 refs., 2 figs., 1 tab.« less

Utilization of photoinduced charge-separated state of donor-acceptor-linked molecules for regulation of cell membrane potential and ion transport.

PubMed

Numata, Tomohiro; Murakami, Tatsuya; Kawashima, Fumiaki; Morone, Nobuhiro; Heuser, John E; Takano, Yuta; Ohkubo, Kei; Fukuzumi, Shunichi; Mori, Yasuo; Imahori, Hiroshi

2012-04-11

The control of ion transport across cell membranes by light is an attractive strategy that allows targeted, fast control of precisely defined events in the biological membrane. Here we report a novel general strategy for the control of membrane potential and ion transport by using charge-separation molecules and light. Delivery of charge-separation molecules to the plasma membrane of PC12 cells by a membranous nanocarrier and subsequent light irradiation led to depolarization of the membrane potential as well as inhibition of the potassium ion flow across the membrane. Photoregulation of the cell membrane potential and ion transport by using charge-separation molecules is highly promising for control of cell functions. © 2012 American Chemical Society

Development of a cerebral circulation model for the automatic control of brain physiology.

PubMed

Utsuki, T

2015-01-01

In various clinical guidelines of brain injury, intracranial pressure (ICP), cerebral blood flow (CBF) and brain temperature (BT) are essential targets for precise management for brain resuscitation. In addition, the integrated automatic control of BT, ICP, and CBF is required for improving therapeutic effects and reducing medical costs and staff burden. Thus, a new model of cerebral circulation was developed in this study for integrative automatic control. With this model, the CBF and cerebral perfusion pressure of a normal adult male were regionally calculated according to cerebrovascular structure, blood viscosity, blood distribution, CBF autoregulation, and ICP. The analysis results were consistent with physiological knowledge already obtained with conventional studies. Therefore, the developed model is potentially available for the integrative control of the physiological state of the brain as a reference model of an automatic control system, or as a controlled object in various control simulations.

Precision Departure Release Capability (PDRC) Final Report

NASA Technical Reports Server (NTRS)

Engelland, Shawn A.; Capps, Richard; Day, Kevin Brian; Kistler, Matthew Stephen; Gaither, Frank; Juro, Greg

2013-01-01

After takeoff, aircraft must merge into en route (Center) airspace traffic flows that may be subject to constraints that create localized demand/capacity imbalances. When demand exceeds capacity, Traffic Management Coordinators (TMCs) and Frontline Managers (FLMs) often use tactical departure scheduling to manage the flow of departures into the constrained Center traffic flow. Tactical departure scheduling usually involves a Call for Release (CFR) procedure wherein the Tower must call the Center to coordinate a release time prior to allowing the flight to depart. In present-day operations release times are computed by the Center Traffic Management Advisor (TMA) decision support tool, based upon manual estimates of aircraft ready time verbally communicated from the Tower to the Center. The TMA-computed release time is verbally communicated from the Center back to the Tower where it is relayed to the Local controller as a release window that is typically three minutes wide. The Local controller will manage the departure to meet the coordinated release time window. Manual ready time prediction and verbal release time coordination are labor intensive and prone to inaccuracy. Also, use of release time windows adds uncertainty to the tactical departure process. Analysis of more than one million flights from January 2011 indicates that a significant number of tactically scheduled aircraft missed their en route slot due to ready time prediction uncertainty. Uncertainty in ready time estimates may result in missed opportunities to merge into constrained en route flows and lead to lost throughput. Next Generation Air Transportation System plans call for development of Tower automation systems capable of computing surface trajectory-based ready time estimates. NASA has developed the Precision Departure Release Capability (PDRC) concept that improves tactical departure scheduling by automatically communicating surface trajectory-based ready time predictions and departure runway assignments to the Center scheduling tool. The PDRC concept also incorporates earlier NASA and FAA research into automation-assisted CFR coordination. The PDRC concept reduces uncertainty by automatically communicating coordinated release times with seconds-level precision enabling TMCs and FLMs to work with target times rather than windows. NASA has developed a PDRC prototype system that integrates the Center's TMA system with a research prototype Tower decision support tool. A two-phase field evaluation was conducted at NASA's North Texas Research Station in Dallas/Fort Worth. The field evaluation validated the PDRC concept and demonstrated reduced release time uncertainty while being used for tactical departure scheduling of more than 230 operational flights over 29 weeks of operations. This paper presents research results from the PDRC research activity. Companion papers present the Concept of Operations and a Technology Description.

Precision Departure Release Capability (PDRC) Technology Description

NASA Technical Reports Server (NTRS)

Engelland, Shawn A.; Capps, Richard; Day, Kevin; Robinson, Corissia; Null, Jody R.

2013-01-01

After takeoff, aircraft must merge into en route (Center) airspace traffic flows which may be subject to constraints that create localized demand-capacity imbalances. When demand exceeds capacity, Traffic Management Coordinators (TMCs) often use tactical departure scheduling to manage the flow of departures into the constrained Center traffic flow. Tactical departure scheduling usually involves use of a Call for Release (CFR) procedure wherein the Tower must call the Center TMC to coordinate a release time prior to allowing the flight to depart. In present-day operations release times are computed by the Center Traffic Management Advisor (TMA) decision support tool based upon manual estimates of aircraft ready time verbally communicated from the Tower to the Center. The TMA-computed release is verbally communicated from the Center back to the Tower where it is relayed to the Local controller as a release window that is typically three minutes wide. The Local controller will manage the departure to meet the coordinated release time window. Manual ready time prediction and verbal release time coordination are labor intensive and prone to inaccuracy. Also, use of release time windows adds uncertainty to the tactical departure process. Analysis of more than one million flights from January 2011 indicates that a significant number of tactically scheduled aircraft missed their en route slot due to ready time prediction uncertainty. Uncertainty in ready time estimates may result in missed opportunities to merge into constrained en route flows and lead to lost throughput. Next Generation Air Transportation System (NextGen) plans call for development of Tower automation systems capable of computing surface trajectory-based ready time estimates. NASA has developed the Precision Departure Release Capability (PDRC) concept that uses this technology to improve tactical departure scheduling by automatically communicating surface trajectory-based ready time predictions to the Center scheduling tool. The PDRC concept also incorporates earlier NASA and FAA research into automation-assisted CFR coordination. The PDRC concept helps reduce uncertainty by automatically communicating coordinated release times with seconds-level precision enabling TMCs to work with target times rather than windows. NASA has developed a PDRC prototype system that integrates the Center's TMA system with a research prototype Tower decision support tool. A two-phase field evaluation was conducted at NASA's North Texas Research Station (NTX) in Dallas-Fort Worth. The field evaluation validated the PDRC concept and demonstrated reduced release time uncertainty while being used for tactical departure scheduling of more than 230 operational flights over 29 weeks of operations. This paper presents the Technology Description. Companion papers include the Final Report and a Concept of Operations.

Precision Departure Release Capability (PDRC): NASA to FAA Research Transition

NASA Technical Reports Server (NTRS)

Engelland, Shawn; Davis, Thomas J.

2013-01-01

After takeoff, aircraft must merge into en route (Center) airspace traffic flows which may be subject to constraints that create localized demand-capacity imbalances. When demand exceeds capacity, Traffic Management Coordinators (TMCs) and Frontline Managers (FLMs) often use tactical departure scheduling to manage the flow of departures into the constrained Center traffic flow. Tactical departure scheduling usually involves use of a Call for Release (CFR) procedure wherein the Tower must call the Center to coordinate a release time prior to allowing the flight to depart. In present-day operations release times are computed by the Center Traffic Management Advisor (TMA) decision support tool based upon manual estimates of aircraft ready time verbally communicated from the Tower to the Center. The TMA-computed release time is verbally communicated from the Center back to the Tower where it is relayed to the Local controller as a release window that is typically three minutes wide. The Local controller will manage the departure to meet the coordinated release time window. Manual ready time prediction and verbal release time coordination are labor intensive and prone to inaccuracy. Also, use of release time windows adds uncertainty to the tactical departure process. Analysis of more than one million flights from January 2011 indicates that a significant number of tactically scheduled aircraft missed their en route slot due to ready time prediction uncertainty. Uncertainty in ready time estimates may result in missed opportunities to merge into constrained en route flows and lead to lost throughput. Next Generation Air Transportation System plans call for development of Tower automation systems capable of computing surface trajectory-based ready time estimates. NASA has developed the Precision Departure Release Capability (PDRC) concept that improves tactical departure scheduling by automatically communicating surface trajectory-based ready time predictions and departure runway assignments to the Center scheduling tool. The PDRC concept also incorporates earlier NASA and FAA research into automation-assisted CFR coordination. The PDRC concept reduces uncertainty by automatically communicating coordinated release times with seconds-level precision enabling TMCs and FLMs to work with target times rather than windows. NASA has developed a PDRC prototype system that integrates the Center's TMA system with a research prototype Tower decision support tool. A two-phase field evaluation was conducted at NASA's North Texas Research Station in Dallas-Fort Worth. The field evaluation validated the PDRC concept and demonstrated reduced release time uncertainty while being used for tactical departure scheduling of more than 230 operational flights over 29 weeks of operations.

Precision Departure Release Capability (PDRC) Concept of Operations

NASA Technical Reports Server (NTRS)

Engelland, Shawn; Capps, Richard A.; Day, Kevin Brian

2013-01-01

After takeoff, aircraft must merge into en route (Center) airspace traffic flows which may be subject to constraints that create localized demandcapacity imbalances. When demand exceeds capacity Traffic Management Coordinators (TMCs) often use tactical departure scheduling to manage the flow of departures into the constrained Center traffic flow. Tactical departure scheduling usually involves use of a Call for Release (CFR) procedure wherein the Tower must call the Center TMC to coordinate a release time prior to allowing the flight to depart. In present-day operations release times are computed by the Center Traffic Management Advisor (TMA) decision support tool based upon manual estimates of aircraft ready time verbally communicated from the Tower to the Center. The TMA-computed release is verbally communicated from the Center back to the Tower where it is relayed to the Local controller as a release window that is typically three minutes wide. The Local controller will manage the departure to meet the coordinated release time window. Manual ready time prediction and verbal release time coordination are labor intensive and prone to inaccuracy. Also, use of release time windows adds uncertainty to the tactical departure process. Analysis of more than one million flights from January 2011 indicates that a significant number of tactically scheduled aircraft missed their en route slot due to ready time prediction uncertainty. Uncertainty in ready time estimates may result in missed opportunities to merge into constrained en route flows and lead to lost throughput. Next Generation Air Transportation System (NextGen) plans call for development of Tower automation systems capable of computing surface trajectory-based ready time estimates. NASA has developed the Precision Departure Release Capability (PDRC) concept that uses this technology to improve tactical departure scheduling by automatically communicating surface trajectory-based ready time predictions to the Center scheduling tool. The PDRC concept also incorporates earlier NASA and FAA research into automation-assisted CFR coordination. The PDRC concept helps reduce uncertainty by automatically communicating coordinated release times with seconds-level precision enabling TMCs to work with target times rather than windows. NASA has developed a PDRC prototype system that integrates the Center's TMA system with a research prototype Tower decision support tool. A two-phase field evaluation was conducted at NASA's North Texas Research Station (NTX) in DallasFort Worth. The field evaluation validated the PDRC concept and demonstrated reduced release time uncertainty while being used for tactical departure scheduling of more than 230 operational flights over 29 weeks of operations. This paper presents the Concept of Operations. Companion papers include the Final Report and a Technology Description. ? SUBJECT:

Dynamics of Reactive Microbial Hotspots in Concentration Gradient.

NASA Astrophysics Data System (ADS)

Hubert, A.; Farasin, J.; Tabuteau, H.; Dufresne, A.; Meheust, Y.; Le Borgne, T.

2017-12-01

In subsurface environments, bacteria play a major role in controlling the kinetics of a broad range of biogeochemical reactions. In such environments, nutrients fluxes and solute concentrations needed for bacteria metabolism may be highly variable in space and intermittent in time. This can lead to the formation of reactive hotspots where and when conditions are favorable to particular microorganisms, hence inducing biogeochemical reaction kinetics that differ significantly from those measured in homogeneous model environments. To investigate the impact of chemical gradients on the spatial structure and temporal dynamics of subsurface microorganism populations, we develop microfluidic cells allowing for a precise control of flow and chemical gradient conditions, as well as quantitative monitoring of the bacteria's spatial distribution and biofilm development. Using the non-motile Escherichia coli JW1908-1 strain and Gallionella capsiferriformans ES-2 as model organisms, we investigate the behavior and development of bacteria over a range of single and double concentration gradients in the concentrations of nutrients, electron donors and electron acceptors. We measure bacterial activity and population growth locally in precisely known hydrodynamic and chemical environments. This approach allows time-resolved monitoring of the location and intensity of reactive hotspots in micromodels as a function of the flow and chemical gradient conditions. We compare reactive microbial hotspot dynamics in our micromodels to classic growth laws and well-known growth parameters for the laboratory model bacteria Escherichia coli.We also discuss consequences for the formation and temporal dynamics of biofilms in the subsurface.

Space Technology for Medical Aids

NASA Technical Reports Server (NTRS)

1982-01-01

Under one of the earliest contracts awarded in the Apollo lunar landing program, Parker Hannifin Corporation developed and produced equipment for controlling the flow of propellants into the mammoth engines of the Saturn moonbooster. Today, Parker is supplying the huge valves that control propellant flow from the Space Shuttle's external fuel tank to the engines of the Shuttle Orbiter as well as the "peanut valve," named for its small size. In 1977, NASA, recognizing the company's special expertise in miniature systems, asked Parker to participate in the development of an implantable artificial sphincter for control of urinary incontinence. The company's peanut valve experience provided an ideal base for a new biomedical project, the Programmable Implantable Medication System (PIMS) for continuous, computer-directed delivery of precisely metered medication -- insulin, for example -- within a patient's body. The work on PIMS also inspired development of Micromed, a related programmable medication device for external, rather than implantable use. The Biomedical Products Division has also applied its fluid handling expertise to a drugless therapy system called Cryomax for the treatment of such disorders as rheumatoid arthritis and lupus.

Scheduling Mission-Critical Flows in Congested and Contested Airborne Network Environments

DTIC Science & Technology

2018-03-01

precision agriculture [64–71]. However, designing, implementing, and testing UAV networks poses numerous interdisciplinary challenges because the...applications including search and rescue, disaster relief, precision agriculture , environmental monitoring, and surveillance. Many of these applications...monitoring enabling precision agriculture ,” in Automation Science and Engineering (CASE), 2015 IEEE International Conference on. IEEE, 2015, pp. 462–469. [65

Miniature Flow-Direction/Pitot-Static Pressure Probes

NASA Technical Reports Server (NTRS)

Ashby, George C., Jr.; Coombs, David S.; Eves, John W.; Price, Howard E.; Vasquez, Peter

1989-01-01

Precision flow-direction/pitot-static pressure probes, ranging from 0.035 to 0.090 inch (0.89 to 2.29 mm) in outside diameter, successfully fabricated and calibrated for use in Langley 20-inch Mach 6 Tunnel. Probes simultaneously measure flow direction and static and pitot pressures in flow fields about configurations in hypersonic flow at temperatures up to 500 degree F (260 degree C).

A flow-free droplet-based device for high throughput polymorphic crystallization.

PubMed

Yang, Shih-Mo; Zhang, Dapeng; Chen, Wang; Chen, Shih-Chi

2015-06-21

Crystallization is one of the most crucial steps in the process of pharmaceutical formulation. In recent years, emulsion-based platforms have been developed and broadly adopted to generate high quality products. However, these conventional approaches such as stirring are still limited in several aspects, e.g., unstable crystallization conditions and broad size distribution; besides, only simple crystal forms can be produced. In this paper, we present a new flow-free droplet-based formation process for producing highly controlled crystallization with two examples: (1) NaCl crystallization reveals the ability to package saturated solution into nanoliter droplets, and (2) glycine crystallization demonstrates the ability to produce polymorphic crystallization forms by controlling the droplet size and temperature. In our process, the saturated solution automatically fills the microwell array powered by degassed bulk PDMS. A critical oil covering step is then introduced to isolate the saturated solution and control the water dissolution rate. Utilizing surface tension, the solution is uniformly packaged in the form of thousands of isolating droplets at the bottom of each microwell of 50-300 μm diameter. After water dissolution, individual crystal structures are automatically formed inside the microwell array. This approach facilitates the study of different glycine growth processes: α-form generated inside the droplets and γ-form generated at the edge of the droplets. With precise temperature control over nanoliter-sized droplets, the growth of ellipsoidal crystalline agglomerates of glycine was achieved for the first time. Optical and SEM images illustrate that the ellipsoidal agglomerates consist of 2-5 μm glycine clusters with inner spiral structures of ~35 μm screw pitch. Lastly, the size distribution of spherical crystalline agglomerates (SAs) produced from microwells of different sizes was measured to have a coefficient variation (CV) of less than 5%, showing crystal sizes can be precisely controlled by microwell sizes with high uniformity. This new method can be used to reliably fabricate monodispersed crystals for pharmaceutical applications.

Application of simple adaptive control to water hydraulic servo cylinder system

NASA Astrophysics Data System (ADS)

Ito, Kazuhisa; Yamada, Tsuyoshi; Ikeo, Shigeru; Takahashi, Koji

2012-09-01

Although conventional model reference adaptive control (MRAC) achieves good tracking performance for cylinder control, the controller structure is much more complicated and has less robustness to disturbance in real applications. This paper discusses the use of simple adaptive control (SAC) for positioning a water hydraulic servo cylinder system. Compared with MRAC, SAC has a simpler and lower order structure, i.e., higher feasibility. The control performance of SAC is examined and evaluated on a water hydraulic servo cylinder system. With the recent increased concerns over global environmental problems, the water hydraulic technique using pure tap water as a pressure medium has become a new drive source comparable to electric, oil hydraulic, and pneumatic drive systems. This technique is also preferred because of its high power density, high safety against fire hazards in production plants, and easy availability. However, the main problems for precise control in a water hydraulic system are steady state errors and overshoot due to its large friction torque and considerable leakage flow. MRAC has been already applied to compensate for these effects, and better control performances have been obtained. However, there have been no reports on the application of SAC for water hydraulics. To make clear the merits of SAC, the tracking control performance and robustness are discussed based on experimental results. SAC is confirmed to give better tracking performance compared with PI control, and a control precision comparable to MRAC (within 10 μm of the reference position) and higher robustness to parameter change, despite the simple controller. The research results ensure a wider application of simple adaptive control in real mechanical systems.

Determination by flow cytometry polyploidy inducing-capacity of colchicine in Cajanus cajan (L.) Mill sp.

PubMed

Udensi, O U; Ontui, V

2013-07-01

The need to optimize flow cytometric analysis for the determination of ploidy level is a worthwhile venture to precisely know at what concentration of a mutagen and at what time of exposure polyploidy could be induced. Flow cytometry was used to determine the polyploidy inducing-capacity of colchicine in pigeon pea (Cajanus cajan (L.) Mill sp). Seeds of pigeon pea were soaked in three different concentrations of colchicine-5 mg, 10 and 15 mg L(-1) for 24, 48 and 72 h, respectively, while the control group was soaked in water. Treated seeds and those from the control were planted in a greenhouse using a Completely Randomized Design (CRD). Results show that colchicine induced tetraploids (4n) and mixoploids (2n+ 4n) as the concentration of colchicine increased and soaking duration. Days to seedling emergence increased as concentration of colchicine and duration of soaking increased while germination rate decreased proportionately with the increase in colchicine concentration and soaking duration but did not significantly affect percentage seedling survival. Explicitly, colchicine has the capacity of inducing polyploidy; especially tetraploids on the seeds of pigeon pea, which obviously could be harnessed for further breeding and improvement of the pigeon pea.

Novel electrospun gas diffusion layers for polymer electrolyte membrane fuel cells: Part II. In operando synchrotron imaging for microscale liquid water transport characterization

NASA Astrophysics Data System (ADS)

Chevalier, S.; Ge, N.; Lee, J.; George, M. G.; Liu, H.; Shrestha, P.; Muirhead, D.; Lavielle, N.; Hatton, B. D.; Bazylak, A.

2017-06-01

This is the second paper in a two-part series in which we investigate the impact of the gas diffusion layer structure on the liquid water distribution in an operating polymer electrolyte membrane (PEM) fuel cell through the procedures of design, fabrication, and testing of novel hydrophobic electrospun gas diffusion layers (eGDLs). In this work, fibre diameters and alignment in eGDLs are precisely controlled, and concurrent synchrotron X-ray radiography and electrochemical impedance spectroscopy (EIS) are used to evaluate the influence of the controlled eGDL parameters on the liquid water distribution and on membrane liquid water content. For eGDLs with small fibre diameters (150-200 nm) and correspondingly smaller pore sizes, reduced liquid water accumulation under the flow field ribs is observed. However, more liquid water is pinned onto the eGDL - at the interface with flow field channels. Orienting fibre alignment perpendicular to the flow field channel direction leads to improved eGDL-catalyst layer contact and prevents rib-channel membrane deformation. On the other hand, eGDLs facilitate significant membrane dry-out, even under highly humidified operating conditions at high current densities.

A multi-functional bubble-based microfluidic system

PubMed Central

Khoshmanesh, Khashayar; Almansouri, Abdullah; Albloushi, Hamad; Yi, Pyshar; Soffe, Rebecca; Kalantar-zadeh, Kourosh

2015-01-01

Recently, the bubble-based systems have offered a new paradigm in microfluidics. Gas bubbles are highly flexible, controllable and barely mix with liquids, and thus can be used for the creation of reconfigurable microfluidic systems. In this work, a hydrodynamically actuated bubble-based microfluidic system is introduced. This system enables the precise movement of air bubbles via axillary feeder channels to alter the geometry of the main channel and consequently the flow characteristics of the system. Mixing of neighbouring streams is demonstrated by oscillating the bubble at desired displacements and frequencies. Flow control is achieved by pushing the bubble to partially or fully close the main channel. Patterning of suspended particles is also demonstrated by creating a large bubble along the sidewalls. Rigorous analytical and numerical calculations are presented to describe the operation of the system. The examples presented in this paper highlight the versatility of the developed bubble-based actuator for a variety of applications; thus providing a vision that can be expanded for future highly reconfigurable microfluidics. PMID:25906043

[Implementation of precision control to achieve the goal of schistosomiasis elimination in China].

PubMed

Zhou, Xiao-nong

2016-02-01

The integrated strategy for schistosomiasis control with focus on infectious source control, which has been implemented since 2004, accelerated the progress towards schistosomiasis control in China, and achieved transmission control of the disease across the country by the end of 2015, which achieved the overall objective of the Mid- and Long-term National Plan for Prevention and Control of Schistosomiasis (2004-2015) on schedule. Then, the goal of schistosomiasis elimination by 2025 was proposed in China in 2014. To achieve this new goal on schedule, we have to address the key issues, and implement precision control measures with more precise identification of control targets, so that we are able to completely eradicate the potential factors leading to resurgence of schistosomiasis transmission and enable the achievement of schistosomiasis elimination on schedule. Precision schistosomiasis control, a theoretical innovation of precision medicine in schistosomiasis control, will provide new insights into schistosomiasis control based on the conception of precision medicine. This paper describes the definition, interventions and the role of precision schistosomiasis control in the elimination of schistosomiasis in China, and demonstrates that sustainable improvement of professionals and integrated control capability at grass-root level is a prerequisite to the implementation of schistosomiasis control, precision schistosomiasis control is a key to the further implementation of the integrated strategy for schistosomiasis control with focus on infectious source control, and precision schistosomiasis control is a guarantee of curing schistosomiasis patients and implementing schistosomiasis control program and interventions.

Advanced optical measuring systems for measuring the properties of fluids and structures

NASA Technical Reports Server (NTRS)

Decker, A. J.

1986-01-01

Four advanced optical models are reviewed for the measurement of visualization of flow and structural properties. Double-exposure, diffuse-illumination, holographic interferometry can be used for three-dimensional flow visualization. When this method is combined with optical heterodyning, precise measurements of structural displacements or fluid density are possible. Time-average holography is well known as a method for displaying vibrational mode shapes, but it also can be used for flow visualization and flow measurements. Deflectometry is used to measure or visualize the deflection of light rays from collimation. Said deflection occurs because of refraction in a fluid or because of reflection from a tilted surface. The moire technique for deflectometry, when combined with optical heterodyning, permits very precise measurements of these quantities. The rainbow schlieren method of deflectometry allows varying deflection angles to be encoded with colors for visualization.

High thermal conductivity liquid metal pad for heat dissipation in electronic devices

NASA Astrophysics Data System (ADS)

Lin, Zuoye; Liu, Huiqiang; Li, Qiuguo; Liu, Han; Chu, Sheng; Yang, Yuhua; Chu, Guang

2018-05-01

Novel thermal interface materials using Ag-doped Ga-based liquid metal were proposed for heat dissipation of electronic packaging and precision equipment. On one hand, the viscosity and fluidity of liquid metal was controlled to prevent leakage; on the other hand, the thermal conductivity of the Ga-based liquid metal was increased up to 46 W/mK by incorporating Ag nanoparticles. A series of experiments were performed to evaluate the heat dissipation performance on a CPU of smart-phone. The results demonstrated that the Ag-doped Ga-based liquid metal pad can effectively decrease the CPU temperature and change the heat flow path inside the smart-phone. To understand the heat flow path from CPU to screen through the interface material, heat dissipation mechanism was simulated and discussed.

Thermal rectification in mass-graded next-nearest-neighbor Fermi-Pasta-Ulam lattices

NASA Astrophysics Data System (ADS)

Romero-Bastida, M.; Miranda-Peña, Jorge-Orlando; López, Juan M.

2017-03-01

We study the thermal rectification efficiency, i.e., quantification of asymmetric heat flow, of a one-dimensional mass-graded anharmonic oscillator Fermi-Pasta-Ulam lattice both with nearest-neighbor (NN) and next-nearest-neighbor (NNN) interactions. The system presents a maximum rectification efficiency for a very precise value of the parameter that controls the coupling strength of the NNN interactions, which also optimizes the rectification figure when its dependence on mass asymmetry and temperature differences is considered. The origin of the enhanced rectification is the asymmetric local heat flow response as the heat reservoirs are swapped when a finely tuned NNN contribution is taken into account. A simple theoretical analysis gives an estimate of the optimal NNN coupling in excellent agreement with our simulation results.

Sound-induced Interfacial Dynamics in a Microfluidic Two-phase Flow

NASA Astrophysics Data System (ADS)

Mak, Sze Yi; Shum, Ho Cheung

2014-11-01

Retrieving sound wave by a fluidic means is challenging due to the difficulty in visualizing the very minute sound-induced fluid motion. This work studies the interfacial response of multiphase systems towards fluctuation in the flow. We demonstrate a direct visualization of music in the form of ripples at a microfluidic aqueous-aqueous interface with an ultra-low interfacial tension. The interface shows a passive response to sound of different frequencies with sufficiently precise time resolution, enabling the recording of musical notes and even subsequent reconstruction with high fidelity. This suggests that sensing and transmitting vibrations as tiny as those induced by sound could be realized in low interfacial tension systems. The robust control of the interfacial dynamics could be adopted for droplet and complex-fiber generation.

Finite element analysis of displacement actuator based on giant magnetostrictive thin film

NASA Astrophysics Data System (ADS)

Yu, Shaopeng; Wang, Bowen; Zhang, Changgeng; Cui, Baozhi

2018-05-01

With the rapid development of science and technology, mechanical and electrical equipment become more and more miniature. In order to achieve precise control in less than 1cm3, the giant magnetostrictive thin film has become a research hotspot. The micro displacement actuator with planar and arc film is designed by the dynamic coupling model based on J-A model and magneto-mechanical effect method which is proposed in this paper. The different structure and thickness of films are analyzed by COMSOL Multiphysics software when the current flows through driving coil. After comparing the simulation results with the test ones, it can be seen that the coupling model is accurate and the structure is reliable. At the same time, MATLAB is used to fit the current density-displacement curve and higher order equation is obtained, and then the feasibility of design can be verified. The actuator with arc structure had advantages of small volume, fast response, high precision, easy integration, etc., which has a broad application prospect in the field of vibration control, micro positioning, robot and so on.

Highly conductive ribbons prepared by stick-slip assembly of organosoluble gold nanoparticles.

PubMed

Lawrence, Jimmy; Pham, Jonathan T; Lee, Dong Yun; Liu, Yujie; Crosby, Alfred J; Emrick, Todd

2014-02-25

Precisely positioning and assembling nanoparticles (NPs) into hierarchical nanostructures is opening opportunities in a wide variety of applications. Many techniques employed to produce hierarchical micrometer and nanoscale structures are limited by complex fabrication of templates and difficulties with scalability. Here we describe the fabrication and characterization of conductive nanoparticle ribbons prepared from surfactant-free organosoluble gold nanoparticles (Au NPs). We used a flow-coating technique in a controlled, stick-slip assembly to regulate the deposition of Au NPs into densely packed, multilayered structures. This affords centimeter-scale long, high-resolution Au NP ribbons with precise periodic spacing in a rapid manner, up to 2 orders-of-magnitude finer and faster than previously reported methods. These Au NP ribbons exhibit linear ohmic response, with conductivity that varies by changing the binding headgroup of the ligands. Controlling NP percolation during sintering (e.g., by adding polymer to retard rapid NP coalescence) enables the formation of highly conductive ribbons, similar to thermally sintered conductive adhesives. Hierarchical, conductive Au NP ribbons represent a promising platform to enable opportunities in sensing, optoelectronics, and electromechanical devices.

A novel approach for determination of free fatty acids in vegetable oils by a flow injection system with manual injection.

PubMed

Ayyildiz, H Filiz; Kara, Huseyin; Sherazi, S T H

2011-12-01

A non-aqueous flow injection method for determining free fatty acid (FFA) content in corn and sunflower oil samples was developed. A single-line manifold system was built by modification of an HPLC for flow injection analysis (FIA). Without pre-treatment, oil samples were injected into a n-propanol solution containing KOH and phenolphthalein (PHP). The main parameters, such as flow rate of carrier phase, length, geometry, inner diameters of the coils and reagent concentration were all optimized. The proposed FIA method was validated for precision, accuracy, linear region, limit of detection (LOD) and limit of quantification (LOQ). The intra- and inter-day measurements of the precision of the method were found to be within the limits of acceptance criteria (RSD < 1%), and were rugged when the method was performed by a different analyst. The linear concentration range was calculated as 0.09-1.50 and 0.07-1.40 FFA% for corn and sunflower oils, correspondingly. The LOD and LOQ were found to be 7.53 × 10(-4)-2.28 × 10(-3) oleic acid % and 7.11 × 10(-4)-2.23 × 10(-3) oleic acid % for corn and sunflower oils, respectively. The results were compared with those obtained by the AOCS (Ca-5a-40) method using statistical t and F tests, and a significant difference was not observed between the methods at a 95% confidence level. The proposed method is suitable for quality control of routine applications due to its simplicity, high sample throughput, and economy of solvents and sample, offering considerable promise as a low cost analytical system that needs minimum human intervention over long periods of time.

Enhancements to the GRIDGEN structured grid generation system for internal and external flow applications

NASA Technical Reports Server (NTRS)

Steinbrenner, John P.; Chawner, John R.

1992-01-01

GRIDGEN is a government domain software package for interactive generation of multiple block grids around general configurations. Though it has been freely available since 1989, it has not been widely embraced by the internal flow community due to a misconception that it was designed for external flow use only. In reality GRIDGEN has always worked for internal flow applications, and GRIDGEN ongoing enhancements are increasing the quality of and efficiency with which grids for external and internal flow problems may be constructed. The software consists of four codes used to perform the four steps of the grid generation process. GRIDBLOCK is first used to decompose the flow domain into a collection of component blocks and then to establish interblock connections and flow solver boundary conditions. GRIDGEN2D is then used to generate surface grids on the outer shell of each component block. GRIDGEN3D generates grid points on the interior of each block, and finally GRIDVUE3D is used to inspect the resulting multiple block grid. Three of these codes (GRIDBLOCK, GRIDGEN2D, and GRIDVUE3D) are highly interactive and graphical in nature, and currently run on Silicon Graphics, Inc., and IBM RS/6000 workstations. The lone batch code (GRIDGEN3D) may be run on any of several Unix based platforms. Surface grid generation in GRIDGEN2D is being improved with the addition of higher order surface definitions (NURBS and parametric surfaces input in IGES format and bicubic surfaces input in PATRAN Neutral File format) and double precision mathematics. In addition, two types of automation have been added to GRIDGEN2D that reduce the learning curve slope for new users and eliminate work for experienced users. Volume grid generation using GRIDGEN3D has been improved via the addition of an advanced hybrid control function formulation that provides both orthogonality and clustering control at the block faces and clustering control on the block interior.

Flagella, flexibility and flow: Physical processes in microbial ecology

NASA Astrophysics Data System (ADS)

Brumley, D. R.; Rusconi, R.; Son, K.; Stocker, R.

2015-12-01

How microorganisms interact with their environment and with their conspecifics depends strongly on their mechanical properties, on the hydrodynamic signatures they generate while swimming and on fluid flows in their environment. The rich fluid-structure interaction between flagella - the appendages microorganisms use for propulsion - and the surrounding flow, has broad reaching effects for both eukaryotic and prokaryotic microorganisms. Here, we discuss selected recent advances in our understanding of the physical ecology of microorganisms, which have hinged on the ability to directly interrogate the movement of individual cells and their swimming appendages, in precisely controlled fluid environments, and to image them at appropriately fast timescales. We review how a flagellar buckling instability can unexpectedly serve a fundamental function in the motility of bacteria, we elucidate the role of hydrodynamics and flexibility in the emergent properties of groups of eukaryotic flagella, and we show how fluid flows characteristic of microbial habitats can strongly bias the migration and spatial distribution of bacteria. The topics covered here are illustrative of the potential inherent in the adoption of experimental methods and conceptual frameworks from physics in understanding the lives of microorganisms.

Chemically generated convective transport in microfluidic system

NASA Astrophysics Data System (ADS)

Shklyaev, Oleg; Das, Sambeeta; Altemose, Alicia; Shum, Henry; Balazs, Anna; Sen, Ayusman

High precision manipulation of small volumes of fluid, containing suspended micron sized objects like cells, viruses, and large molecules, is one of the main goals in designing modern lab-on-a-chip devices which can find a variety of chemical and biological applications. To transport the cargo toward sensing elements, typical microfluidic devices often use pressure driven flows. Here, we propose to use enzymatic chemical reactions which decompose reagent into less dense products and generate flows that can transport particles. Density variations that lead to flow in the assigned direction are created between the place where reagent is fed into the solution and the location where it is decomposed by enzymes attached to the surface of the microchannel. When the reagent is depleted, the fluid motion stops and particles sediment to the bottom. We demonstrate how the choice of chemicals, leading to specific reaction rates, can affect the transport properties. In particular, we show that the intensity of the fluid flow, the final location of cargo, and the time for cargo delivery are controlled by the amount and type of reagent in the system.

Bonding thermoplastic polymers

DOEpatents

Wallow, Thomas I [Fremont, CA; Hunter, Marion C [Livermore, CA; Krafcik, Karen Lee [Livermore, CA; Morales, Alfredo M [Livermore, CA; Simmons, Blake A [San Francisco, CA; Domeier, Linda A [Danville, CA

2008-06-24

We demonstrate a new method for joining patterned thermoplastic parts into layered structures. The method takes advantage of case-II permeant diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. It is capable of producing bonds characterized by cohesive failure while preserving the fidelity of patterned features in the bonding surfaces. This approach is uniquely suited to production of microfluidic multilayer structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometer length scales. The bond enhancing procedure is easily integrated in standard process flows and requires no specialized equipment.

Automatic cytometric device using multiple wavelength excitations

NASA Astrophysics Data System (ADS)

Rongeat, Nelly; Ledroit, Sylvain; Chauvet, Laurence; Cremien, Didier; Urankar, Alexandra; Couderc, Vincent; Nérin, Philippe

2011-05-01

Precise identification of eosinophils, basophils, and specific subpopulations of blood cells (B lymphocytes) in an unconventional automatic hematology analyzer is demonstrated. Our specific apparatus mixes two excitation radiations by means of an acousto-optics tunable filter to properly control fluorescence emission of phycoerythrin cyanin 5 (PC5) conjugated to antibodies (anti-CD20 or anti-CRTH2) and Thiazole Orange. This way our analyzer combining techniques of hematology analysis and flow cytometry based on multiple fluorescence detection, drastically improves the signal to noise ratio and decreases the spectral overlaps impact coming from multiple fluorescence emissions.

Doppler Global Velocimeter Development for the Large Wind Tunnels at Ames Research Center

NASA Technical Reports Server (NTRS)

Reinath, Michael S.

1997-01-01

Development of an optical, laser-based flow-field measurement technique for large wind tunnels is described. The technique uses laser sheet illumination and charged coupled device detectors to rapidly measure flow-field velocity distributions over large planar regions of the flow. Sample measurements are presented that illustrate the capability of the technique. An analysis of measurement uncertainty, which focuses on the random component of uncertainty, shows that precision uncertainty is not dependent on the measured velocity magnitude. For a single-image measurement, the analysis predicts a precision uncertainty of +/-5 m/s. When multiple images are averaged, this uncertainty is shown to decrease. For an average of 100 images, for example, the analysis shows that a precision uncertainty of +/-0.5 m/s can be expected. Sample applications show that vectors aligned with an orthogonal coordinate system are difficult to measure directly. An algebraic transformation is presented which converts measured vectors to the desired orthogonal components. Uncertainty propagation is then used to show how the uncertainty propagates from the direct measurements to the orthogonal components. For a typical forward-scatter viewing geometry, the propagation analysis predicts precision uncertainties of +/-4, +/-7, and +/-6 m/s, respectively, for the U, V, and W components at 68% confidence.

Polymer relaxation and stretching dynamics in semi-dilute DNA solutions: a single molecule study

NASA Astrophysics Data System (ADS)

Hsiao, Kai-Wen; Brockman, Christopher; Schroeder, Charles

2015-03-01

In this work, we study polymer relaxation and stretching dynamics in semi-dilute DNA solutions using single molecule techniques. Using this approach, we uncover a unique scaling relation for longest polymer relaxation time that falls in the crossover regime described by semi-flexible polymer solutions, which is distinct from truly flexible polymer chains. In addition, we performed a series of step-strain experiments on single polymers in semi-dilute solutions in planar extensional flow using an automated microfluidic trap. In this way, we are able to precisely control the flow strength and the amount of strain applied to single polymer chains, thereby enabling direct observation of the full stretching and relaxation process in semi-dilute solutions during transient start-up and flow cessation. Interestingly, we observe polymer individualism in the conformation of single chains in semi-dilute solutions, which to our knowledge has not yet been observed. In addition, we observe the relaxation data can be explained by a multi-exponential decay process after flow cessation in semi-dilute solutions. Overall, our work reports key advance in non-dilute polymer systems from a molecular perspective via direct observation of dynamics in strong flows. DOW fellowship.

Application of Dynamic Mode Decomposition: Temporal Evolution of Flow Structures in an Aneurysm

NASA Astrophysics Data System (ADS)

Conlin, William; Yu, Paulo; Durgesh, Vibhav

2017-11-01

An aneurysm is an enlargement of a weakened arterial wall that can be fatal or debilitating on rupture. Aneurysm hemodynamics is integral to developing an understanding of aneurysm formation, growth, and rupture. The flow in an aneurysm exhibits complex fluid dynamics behavior due to an inherent unsteady inflow condition and its interactions with large-scale flow structures present in the aneurysm. The objective of this study is to identify the large-scale structures in the aneurysm, study temporal behavior, and quantify their interaction with the inflow condition. For this purpose, detailed Particle Image Velocimetry (PIV) measurements were performed at the center plane of an idealized aneurysm model for a range of inflow conditions. Inflow conditions were precisely controlled using a ViVitro SuperPump system. Dynamic Modal Decomposition (DMD) of the velocity field was used to identify coherent structures and their temporal behavior. DMD was successful in capturing the large-scale flow structures and their temporal behavior. A low dimensional approximation to the flow field was obtained with the most relevant dynamic modes and was used to obtain temporal information about the coherent structures and their interaction with the inflow, formation, evolution, and growth.

Keep-Left Behavior Induced by Asymmetrically Profiled Walls

NASA Astrophysics Data System (ADS)

Oliveira, C. L. N.; Vieira, A. P.; Helbing, D.; Andrade, J. S.; Herrmann, H. J.

2016-01-01

We show, computationally and analytically, that asymmetrically shaped walls can organize the flow of pedestrians driven in opposite directions through a corridor. Precisely, a two-lane ordered state emerges in which people always walk on the left-hand side (or right-hand side), controlled by the system's parameters. This effect depends on features of the channel geometry, such as the asymmetry of the profile and the channel width, as well as on the density and the drift velocity of pedestrians, and the intensity of noise. We investigate in detail the influence of these parameters on the flow and discover a crossover between ordered and disordered states. Our results show that an ordered state only appears within a limited range of drift velocities. Moreover, increasing noise may suppress such flow organization, but the flow is always sustained. This is in contrast with the "freezing by heating" phenomenon according to which pedestrians tend to clog in smooth channels for strong noise [Phys. Rev. Lett. 84, 1240 (2000)]. Therefore, the ratchetlike effect proposed here acts on the system not only to induce a "keep-left" behavior but also to prevent the freezing by heating clogging phenomenon. Besides pedestrian flow, this new phenomenon has other potential applications in microfluidics systems.

A microfluidic system with integrated molecular imprinting polymer films for surface plasmon resonance detection

NASA Astrophysics Data System (ADS)

Huang, Shih-Chiang; Lee, Gwo-Bin; Chien, Fan-Ching; Chen, Shean-Jen; Chen, Wen-Janq; Yang, Ming-Chang

2006-07-01

This paper presents a novel microfluidic system with integrated molecular imprinting polymer (MIP) films designed for surface plasmon resonance (SPR) biosensing of multiple nanoscale biomolecules. The innovative microfluidic chip uses pneumatic microvalves and micropumps to transport a precise amount of the biosample through multiple microchannels to sensing regions containing the locally spin-coated MIP films. The signals of SPR biosensing are basically proportional to the number of molecules adsorbed on the MIP films. Hence, a precise control of flow rates inside microchannels is important to determine the adsorption amount of the molecules in the SPR/MIP chips. The integration of micropumps and microvalves can automate the sample introduction process and precisely control the amount of the sample injection to the microfluidic system. The proposed biochip enables the label-free biosensing of biomolecules in an automatic format, and provides a highly sensitive, highly specific and high-throughput detection performance. Three samples, i.e. progesterone, cholesterol and testosterone, are successfully detected using the developed system. The experimental results show that the proposed SPR/MIP microfluidic chip provides a comparable sensitivity to that of large-scale SPR techniques, but with reduced sample consumption and an automatic format. As such, the developed biochip has significant potential for a wide variety of nanoscale biosensing applications. The preliminary results of the current paper were presented at Transducers 2005, Seoul, Korea, 5-9 June 2005.

Triggering of frequent turbidity currents in Monterey Canyon and the role of antecedent conditioning

NASA Astrophysics Data System (ADS)

Clare, M. A.; Rosenberger, K. J.; Talling, P.; Barry, J.; Maier, K. L.; Parsons, D. R.; Simmons, S.; Gales, J. A.; Gwiazda, R.; McGann, M.; Paull, C. K.

2017-12-01

Turbidity currents pose a hazard to seafloor infrastructure, deliver organic carbon and nutrients to deep-sea communities, and form economically important deposits. Thus, determining the tempo of turbidity current activity and whether different triggers result in different flow modes is important. Identification of specific triggers is challenging, however, because most studies of turbidity currents are based on their deposits. New direct monitoring of flows and environmental conditions provides the necessary temporal constraints to identify triggering mechanisms. The Coordinated Canyon Experiment (CCE) in Monterey Canyon, offshore California is the most ambitious attempt yet to measure turbidity flows and their triggers. The CCE provides precise constraint on flow timing, initiation, and potential triggers based on measurements at 7 different instrumented moorings and 2 metocean buoys. Fifteen turbidity flows were measured in 18 months; with recorded velocities >8 m/s and run-outs of up to 50 km. Presence of live estuarine foraminifera within moored sediment traps suggests that that flows originated in water depths of <10 m, but it is unclear specifically how these flows were triggered. Turbidity currents are thought to be triggered by processes including earthquakes, river floods and storm waves. Here we analyse seismicity, local river discharge, internal tides, wave height, direction and period data. We identify no clear control of any of these individual variables on flow timing. None of the recorded earthquakes (

Programmable controller system for wind tunnel diversion vanes

NASA Technical Reports Server (NTRS)

King, R. F.

1982-01-01

A programmable controller (PC) system automatic sequence control, which acts as a supervisory controller for the servos, selects the proper drives, and automatically sequences the vanes, was developed for use in a subsonic wind tunnel. Tunnel modifications include a new second test section (80 ft x 100 ft with a maximum air speed capability of 110 knots) and an increase in maximum velocity flow from 200 knots to 300 knots. A completely automatic sequence control is necessary in order to allow intricate motion of the 14 triangularly arranged vanes which can be as large as 70 ft high x 35 ft wide and which require precise acceleration and deceleration control. Rate servos on each drive aid in this control, and servo cost was minimized by using four silicon controlled rectifier controllers to control the 20 dc drives. The PC has a programming capacity which facilitated the implementation of extensive logic design. A series of diagrams sequencing the vanes and a block diagram of the system are included.

Characterization of the supersonic flowing microwave discharge using two dimensional plasma tomography

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

Nikolic, M.; Samolov, A.; Popovic, S.

2013-03-14

A tomographic numerical method based on the two-dimensional Radon formula for a cylindrical cavity has been employed for obtaining spatial distributions of the argon excited levels. The spectroscopy measurements were taken at different positions and directions to observe populations of excited species in the plasmoid region and the corresponding excitation temperatures. Excited argon states are concentrated near the tube walls, thus, confirming the assumption that the post discharge plasma is dominantly sustained by travelling surface wave. An automated optical measurement system has been developed for reconstruction of local plasma parameters of the plasmoid structure formed in an argon supersonic flowingmore » microwave discharge. The system carries out angle and distance measurements using a rotating, flat mirror, as well as two high precision stepper motors operated by a microcontroller-based system and several sensors for precise feedback control.« less

Mass Separation by Metamaterials

PubMed Central

Restrepo-Flórez, Juan Manuel; Maldovan, Martin

2016-01-01

Being able to manipulate mass flow is critically important in a variety of physical processes in chemical and biomolecular science. For example, separation and catalytic systems, which requires precise control of mass diffusion, are crucial in the manufacturing of chemicals, crystal growth of semiconductors, waste recovery of biological solutes or chemicals, and production of artificial kidneys. Coordinate transformations and metamaterials are powerful methods to achieve precise manipulation of molecular diffusion. Here, we introduce a novel approach to obtain mass separation based on metamaterials that can sort chemical and biomolecular species by cloaking one compound while concentrating the other. A design strategy to realize such metamaterial using homogeneous isotropic materials is proposed. We present a practical case where a mixture of oxygen and nitrogen is manipulated using a metamaterial that cloaks nitrogen and concentrates oxygen. This work lays the foundation for molecular mass separation in biophysical and chemical systems through metamaterial devices. PMID:26912419

Two Phase Admission Control for QoS Mobile Ad Hoc Networks

NASA Astrophysics Data System (ADS)

Chen, Chien-Sheng; Su, Yi-Wen; Liu, Wen-Hsiung; Chi, Ching-Lung

In this paper a novel and effective two phase admission control (TPAC) for QoS mobile ad hoc networks is proposed that satisfies the real-time traffic requirements in mobile ad hoc networks. With a limited amount of extra overhead, TPAC can avoid network congestions by a simple and precise admission control which blocks most of the overloading flow-requests in the route discovery process. When compared with previous QoS routing schemes such as QoS-aware routing protocol and CACP protocols, it is shown from system simulations that the proposed scheme can increase the system throughput and reduce both the dropping rate and the end-to-end delay. Therefore, TPAC is surely an effective QoS-guarantee protocol to provide for real-time traffic.

Hydrodynamic fabrication of structurally gradient ZnO nanorods.

PubMed

Kim, Hyung Min; Youn, Jae Ryoun; Song, Young Seok

2016-02-26

We studied a new approach where structurally gradient nanostructures were fabricated by means of hydrodynamics. Zinc oxide (ZnO) nanorods were synthesized in a drag-driven rotational flow in a controlled manner. The structural characteristics of nanorods such as orientation and diameter were determined by momentum and mass transfer at the substrate surface. The nucleation of ZnO was induced by shear stress which plays a key role in determining the orientation of ZnO nanorods. The nucleation and growth of such nanostructures were modeled theoretically and analyzed numerically to understand the underlying physics of the fabrication of nanostructures controlled by hydrodynamics. The findings demonstrated that the precise control of momentum and mass transfer enabled the formation of ZnO nanorods with a structural gradient in diameter and orientation.

Impact of sediment load on manning coefficient in supercritical shallow flow on steep slopes

USDA-ARS?s Scientific Manuscript database

The Manning equation is one of the most widely used formulas for calculating velocity of overland flow in hydrological and erosion models. Precise estimation of the Manning’s friction coefficient (n) is critical to simulate the processes of overland flow and soil erosion. Few studies were conducted ...

Computerized microfluidic cell culture using elastomeric channels and Braille displays.

PubMed

Gu, Wei; Zhu, Xiaoyue; Futai, Nobuyuki; Cho, Brenda S; Takayama, Shuichi

2004-11-09

Computer-controlled microfluidics would advance many types of cellular assays and microscale tissue engineering studies wherever spatiotemporal changes in fluidics need to be defined. However, this goal has been elusive because of the limited availability of integrated, programmable pumps and valves. This paper demonstrates how a refreshable Braille display, with its grid of 320 vertically moving pins, can power integrated pumps and valves through localized deformations of channel networks within elastic silicone rubber. The resulting computerized fluidic control is able to switch among: (i) rapid and efficient mixing between streams, (ii) multiple laminar flows with minimal mixing between streams, and (iii) segmented plug-flow of immiscible fluids within the same channel architecture. The same control method is used to precisely seed cells, compartmentalize them into distinct subpopulations through channel reconfiguration, and culture each cell subpopulation for up to 3 weeks under perfusion. These reliable microscale cell cultures showed gradients of cellular behavior from C2C12 myoblasts along channel lengths, as well as differences in cell density of undifferentiated myoblasts and differentiation patterns, both programmable through different flow rates of serum-containing media. This technology will allow future microscale tissue or cell studies to be more accessible, especially for high-throughput, complex, and long-term experiments. The microfluidic actuation method described is versatile and computer programmable, yet simple, well packaged, and portable enough for personal use.

Computerized microfluidic cell culture using elastomeric channels and Braille displays

PubMed Central

Gu, Wei; Zhu, Xiaoyue; Futai, Nobuyuki; Cho, Brenda S.; Takayama, Shuichi

2004-01-01

Computer-controlled microfluidics would advance many types of cellular assays and microscale tissue engineering studies wherever spatiotemporal changes in fluidics need to be defined. However, this goal has been elusive because of the limited availability of integrated, programmable pumps and valves. This paper demonstrates how a refreshable Braille display, with its grid of 320 vertically moving pins, can power integrated pumps and valves through localized deformations of channel networks within elastic silicone rubber. The resulting computerized fluidic control is able to switch among: (i) rapid and efficient mixing between streams, (ii) multiple laminar flows with minimal mixing between streams, and (iii) segmented plug-flow of immiscible fluids within the same channel architecture. The same control method is used to precisely seed cells, compartmentalize them into distinct subpopulations through channel reconfiguration, and culture each cell subpopulation for up to 3 weeks under perfusion. These reliable microscale cell cultures showed gradients of cellular behavior from C2C12 myoblasts along channel lengths, as well as differences in cell density of undifferentiated myoblasts and differentiation patterns, both programmable through different flow rates of serum-containing media. This technology will allow future microscale tissue or cell studies to be more accessible, especially for high-throughput, complex, and long-term experiments. The microfluidic actuation method described is versatile and computer programmable, yet simple, well packaged, and portable enough for personal use. PMID:15514025

Impact of Inflow Conditions on Coherent Structures in an Aneurysm

NASA Astrophysics Data System (ADS)

Yu, Paulo; Durgesh, Vibhav; Johari, Hamid

2017-11-01

An aneurysm is an enlargement of a weakened arterial wall that can be debilitating or fatal on rupture. Studies have shown that hemodynamics is integral to developing an understanding of aneurysm formation, growth, and rupture. This investigation focuses on a comprehensive study of the impact of varying inflow conditions and aneurysm shapes on spatial and temporal behavior of flow parameters and structures in an aneurysm. Two different shapes of an idealized rigid aneurysm model were studied and the non-dimensional frequency and Reynolds number were varied between 2-5 and 50-250, respectively. A ViVitro Labs SuperPump system was used to precisely control inflow conditions. Particle Image Velocimetry (PIV) measurements were performed at three different locations inside the aneurysm sac to obtain detailed velocity flow field information. The results of this study showed that aneurysm morphology significantly impacts spatial and temporal behavior of large-scale flow structures as well as wall shear stress distribution. The flow behavior and structures showed a significant difference with change in inflow conditions. A primary fluctuating flow structure was observed for Reynolds number of 50, while for higher Reynolds numbers, primary and secondary flow structures were observed. Furthermore, the paths of these coherent structures were dependent on aneurysm shape and inflow parameters.

Inhibition of viscous fluid fingering: A variational scheme for optimal flow rates

NASA Astrophysics Data System (ADS)

Miranda, Jose; Dias, Eduardo; Alvarez-Lacalle, Enrique; Carvalho, Marcio

2012-11-01

Conventional viscous fingering flow in radial Hele-Shaw cells employs a constant injection rate, resulting in the emergence of branched interfacial shapes. The search for mechanisms to prevent the development of these bifurcated morphologies is relevant to a number of areas in science and technology. A challenging problem is how best to choose the pumping rate in order to restrain growth of interfacial amplitudes. We use an analytical variational scheme to look for the precise functional form of such an optimal flow rate. We find it increases linearly with time in a specific manner so that interface disturbances are minimized. Experiments and nonlinear numerical simulations support the effectiveness of this particularly simple, but not at all obvious, pattern controlling process. J.A.M., E.O.D. and M.S.C. thank CNPq/Brazil for financial support. E.A.L. acknowledges support from Secretaria de Estado de IDI Spain under project FIS2011-28820-C02-01.

Stability of sulfur slopes on Io

NASA Technical Reports Server (NTRS)

Clow, G. D.; Carr, M. H.

1980-01-01

The mechanical properties of elemental sulfur are such that the upper crust of Io cannot be primarily sulfur. For heat flows in the range 100-1000 ergs/sq cm sec sulfur becomes ductile within several hundred meters of the surface and would prevent the formation of calderas with depths greater than this. However, the one caldera for which precise depth data are available is 2 km deep, and this value may be typical. A study of the mechanical equilibrium of simple slopes shows that the depth to the zone of rapid ductile flow strongly controls the maximum heights for sulfur slopes. Sulfur scarps with heights greater than 1 km will fail for all heat flows greater than 180 ergs/sq cm sec and slope angles greater than 22.5 deg. The observed relief on Io is inconsistent with that anticipated for a predominantly sulfur crust. However, a silicate crust with several percent sulfur included satisfies both the mechanical constraints and the observed presence of sulfur on Io.

Monitoring the orientation of rare-earth-doped nanorods for flow shear tomography.

PubMed

Kim, Jongwook; Michelin, Sébastien; Hilbers, Michiel; Martinelli, Lucio; Chaudan, Elodie; Amselem, Gabriel; Fradet, Etienne; Boilot, Jean-Pierre; Brouwer, Albert M; Baroud, Charles N; Peretti, Jacques; Gacoin, Thierry

2017-09-01

Rare-earth phosphors exhibit unique luminescence polarization features originating from the anisotropic symmetry of the emitter ion's chemical environment. However, to take advantage of this peculiar property, it is necessary to control and measure the ensemble orientation of the host particles with a high degree of precision. Here, we show a methodology to obtain the photoluminescence polarization of Eu-doped LaPO 4 nanorods assembled in an electrically modulated liquid-crystalline phase. We measure Eu 3+ emission spectra for the three main optical configurations (σ, π and α, depending on the direction of observation and the polarization axes) and use them as a reference for the nanorod orientation analysis. Based on the fact that flowing nanorods tend to orient along the shear strain profile, we use this orientation analysis to measure the local shear rate in a flowing liquid. The potential of this approach is then demonstrated through tomographic imaging of the shear rate distribution in a microfluidic system.

Brief Communication: A low-cost Arduino®-based wire extensometer for earth flow monitoring

NASA Astrophysics Data System (ADS)

Guerriero, Luigi; Guerriero, Giovanni; Grelle, Gerardo; Guadagno, Francesco M.; Revellino, Paola

2017-06-01

Continuous monitoring of earth flow displacement is essential for the understanding of the dynamic of the process, its ongoing evolution and designing mitigation measures. Despite its importance, it is not always applied due to its expense and the need for integration with additional sensors to monitor factors controlling movement. To overcome these problems, we developed and tested a low-cost Arduino-based wire-rail extensometer integrating a data logger, a power system and multiple digital and analog inputs. The system is equipped with a high-precision position transducer that in the test configuration offers a measuring range of 1023 mm and an associated accuracy of ±1 mm, and integrates an operating temperature sensor that should allow potential thermal drift that typically affects this kind of systems to be identified and corrected. A field test, conducted at the Pietrafitta earth flow where additional monitoring systems had been installed, indicates a high reliability of the measurement and a high monitoring stability without visible thermal drift.

Syringe Pump Performance Maintained with IV Filter Use During Low Flow Rate Delivery for Pediatric Patients.

PubMed

Chau, Destiny F; Vasilopoulos, Terrie; Schoepf, Miriam; Zhang, Christina; Fahy, Brenda G

2016-09-01

Complex surgical and critically ill pediatric patients rely on syringe infusion pumps for precise delivery of IV medications. Low flow rates and in-line IV filter use may affect drug delivery. To determine the effects of an in-line filter to remove air and/or contaminants on syringe pump performance at low flow rates, we compared the measured rates with the programmed flow rates with and without in-line IV filters. Standardized IV infusion assemblies with and without IV filters (filter and control groups) attached to a 10-mL syringe were primed and then loaded onto a syringe pump and connected to a 16-gauge, 16-cm single-lumen catheter. The catheter was suspended in a normal saline fluid column to simulate the back pressure from central venous circulation. The delivered infusate was measured by gravimetric methods at predetermined time intervals, and flow rate was calculated. Experimental trials for initial programmed rates of 1.0, 0.8, 0.6, and 0.4 mL/h were performed in control and filter groups. For each trial, the flow rate was changed to double the initial flow rate and was then returned to the initial flow rate to analyze pump performance for titration of rates often required during medication administration. These conditions (initial rate, doubling of initial rate, and return to initial rate) were analyzed separately for steady-state flow rate and time to steady state, whereas their average was used for percent deviation analysis. Differences between control and filter groups were assessed using Student t tests with adjustment for multiplicity (using n = 3 replications per group). Mean time from 0 to initial flow (startup delay) was <1 minute in both groups with no statistical difference between groups (P = 1.0). The average time to reach steady-state flow after infusion startup or rate changes was not statistically different between the groups (range, 0.8-5.5 minutes), for any flow rate or part of the trial (initial rate, doubling of initial rate, and return to initial rate), although the study was underpowered to detect small time differences. Overall, the mean steady-state flow rate for each trial was below the programmed flow rate with negative mean percent deviations for each trial. In the 1.0-mL/h initial rate trial, the steady-state flow rate attained was lower in the filter than the control group for the initial rate (P = 0.04) and doubling of initial rate (P = 0.04) with a trend during the return to initial rate (P = 0.06), although this same effect was not observed when doubling the initial rate trials of 0.8 or 0.6 mL/h or any other rate trials compared with the control group. With low flow rates used in complex surgical and pediatric critically ill patients, the addition of IV filters did not confer statistically significant changes in startup delay, flow variability, or time to reach steady-state flow of medications administered by syringe infusion pumps. The overall flow rate was lower than programmed flow rate with or without a filter.

The Precision Field Lysimeter Concept

NASA Astrophysics Data System (ADS)

Fank, J.

2009-04-01

The understanding and interpretation of leaching processes have improved significantly during the past decades. Unlike laboratory experiments, which are mostly performed under very controlled conditions (e.g. homogeneous, uniform packing of pre-treated test material, saturated steady-state flow conditions, and controlled uniform hydraulic conditions), lysimeter experiments generally simulate actual field conditions. Lysimeters may be classified according to different criteria such as type of soil block used (monolithic or reconstructed), drainage (drainage by gravity or vacuum or a water table may be maintained), or weighing or non-weighing lysimeters. In 2004 experimental investigations have been set up to assess the impact of different farming systems on groundwater quality of the shallow floodplain aquifer of the river Mur in Wagna (Styria, Austria). The sediment is characterized by a thin layer (30 - 100 cm) of sandy Dystric Cambisol and underlying gravel and sand. Three precisely weighing equilibrium tension block lysimeters have been installed in agricultural test fields to compare water flow and solute transport under (i) organic farming, (ii) conventional low input farming and (iii) extensification by mulching grass. Specific monitoring equipment is used to reduce the well known shortcomings of lysimeter investigations: The lysimeter core is excavated as an undisturbed monolithic block (circular, 1 m2 surface area, 2 m depth) to prevent destruction of the natural soil structure, and pore system. Tracing experiments have been achieved to investigate the occurrence of artificial preferential flow and transport along the walls of the lysimeters. The results show that such effects can be neglected. Precisely weighing load cells are used to constantly determine the weight loss of the lysimeter due to evaporation and transpiration and to measure different forms of precipitation. The accuracy of the weighing apparatus is 0.05 kg, or 0.05 mm water equivalent respectively. The different soil horizons in the lysimeters are equipped with sensors to measure soil temperature, water content and soil tension. Suction cups are used to get soil water samples. The lower boundary of the lysimeter is designed to maintain equilibrium between the suction applied to the leachate collection system and soil matrix potential thus the suction applied may vary depending on natural conditions - measured using tensiometers - in the field. The lysimeters are built in directly in a test area of 1000 m2 with the same vegetation to prevent island effects on evotranspiration. The topmost part of the lysimeter is realized as a removable ring that mechanical cultivation is possible in the same manner as at the test field. In this presentation the concept and the implementation of the Precision Field Lysimeter is shown. First results on water and solute balances of a 4 years investigation period are discussed.

Hierarchical Biomolecular Emulsions Using 3-D Microfluidics with Uniform Surface Chemistry.

PubMed

Toprakcioglu, Zenon; Levin, Aviad; Knowles, Tuomas P J

2017-11-13

Microfluidic devices can be used to produce single, double and higher order emulsions, where droplet sizes can be precisely controlled and modulated. Such emulsions have great potential for the storage and study of biomolecules, including peptides and proteins. However, advancement of this technique has remained challenging due to the tendency of various biomolecules to adhere to the surface of the formed channels, resulting in changes in surface wetting and fouling on the micrometer scale. Thus, precise control of surface wettability plays a crucial role in the processes that govern droplet formation. Here, we report an approach for producing both water-oil-water (w/o/w) and oil-water-oil (o/w/o) double emulsions without any need for surface modification, an enabling feature for biomolecular encapsulation. Using this strategy, we show that the number of monodisperse encapsulated internal droplets can be controlled systematically and reproducibly by suitable adjustment of the relevant flow rates, and ranges from 1 to 40 in the case of w/o/w emulsions. We further demonstrate that the number of internal droplets scales linearly with the reciprocal flow rate of the outer continuous phase, when the inner and middle phase flow rates are kept constant. We demonstrate that this approach is suitable for forming double emulsions where the inner phase consists of reconstituted silk protein solution whereby incubation of the internal droplets can be induced to form a gel resulting in silk fibroin microgels surrounded by an external oil shell. Finally, for o/w/o emulsions, we show that single or multiple monodisperse internal droplets can be encapsulated with a size that ranges over 1 order of magnitude, from ca. 10 μm to >100 μm. Moreover, o/w/o emulsions where the middle phase consists of silk fibroin solution were prepared and by allowing the protein to aggregate, a core-shell structure was formed. This microfluidic strategy allows for multiple emulsions to be generated drop by drop for biomolecular solutions with potential applications in the biomedical and pharmaceutical fields.

Methods for stable recording of short-circuit current in a Na+-transporting epithelium.

PubMed

Gondzik, Veronika; Awayda, Mouhamed S

2011-07-01

Epithelial Na(+) transport as measured by a variety of techniques, including the short-circuit current technique, has been described to exhibit a "rundown" phenomenon. This phenomenon manifests as time-dependent decrease of current and resistance and precludes the ability to carry out prolonged experiments aimed at examining the regulation of this transport. We developed methods for prolonged stable recordings of epithelial Na(+) transport using modifications of the short-circuit current technique and commercial Ussing-type chambers. We utilize the polarized MDCK cell line expressing the epithelial Na(+) channel (ENaC) to describe these methods. Briefly, existing commercial chambers were modified to allow continuous flow of Ringer solution and precise control of such flow. Chamber manifolds and associated plumbing were modified to allow precise temperature clamp preventing temperature oscillations. Recording electrodes were modified to eliminate the use of KCl and prevent membrane depolarization from KCl leakage. Solutions utilized standard bicarbonate-based buffers, but all gasses were prehydrated to clamp buffer osmolarity. We demonstrate that these modifications result in measurements of current and resistance that are stable for at least 2 h. We further demonstrate that drifts in osmolarity similar to those obtained before prior to our modifications can lead to a decrease of current and resistance similar to those attributed to rundown.

Precision and accuracy of clinical quantification of myocardial blood flow by dynamic PET: A technical perspective.

PubMed

Moody, Jonathan B; Lee, Benjamin C; Corbett, James R; Ficaro, Edward P; Murthy, Venkatesh L

2015-10-01

A number of exciting advances in PET/CT technology and improvements in methodology have recently converged to enhance the feasibility of routine clinical quantification of myocardial blood flow and flow reserve. Recent promising clinical results are pointing toward an important role for myocardial blood flow in the care of patients. Absolute blood flow quantification can be a powerful clinical tool, but its utility will depend on maintaining precision and accuracy in the face of numerous potential sources of methodological errors. Here we review recent data and highlight the impact of PET instrumentation, image reconstruction, and quantification methods, and we emphasize (82)Rb cardiac PET which currently has the widest clinical application. It will be apparent that more data are needed, particularly in relation to newer PET technologies, as well as clinical standardization of PET protocols and methods. We provide recommendations for the methodological factors considered here. At present, myocardial flow reserve appears to be remarkably robust to various methodological errors; however, with greater attention to and more detailed understanding of these sources of error, the clinical benefits of stress-only blood flow measurement may eventually be more fully realized.

Crafting threads of diblock copolymer micelles via flow-enabled self-assembly.

PubMed

Li, Bo; Han, Wei; Jiang, Beibei; Lin, Zhiqun

2014-03-25

Hierarchically assembled amphiphilic diblock copolymer micelles were exquisitely crafted over large areas by capitalizing on two concurrent self-assembling processes at different length scales, namely, the periodic threads composed of a monolayer or a bilayer of diblock copolymer micelles precisely positioned by flow-enabled self-assembly (FESA) on the microscopic scale and the self-assembly of amphiphilic diblock copolymer micelles into ordered arrays within an individual thread on the nanometer scale. A minimum spacing between two adjacent threads λmin was observed. A model was proposed to rationalize the relationship between the thread width and λmin. Such FESA of diblock copolymer micelles is remarkably controllable and easy to implement. It opens up possibilities for lithography-free positioning and patterning of diblock copolymer micelles for various applications in template fabrication of periodic inorganic nanostructures, nanoelectronics, optoelectronics, magnetic devices, and biotechnology.

Mechanobiology of Platelets: Techniques to Study the Role of Fluid Flow and Platelet Retraction Forces at the Micro- and Nano-Scale

PubMed Central

Feghhi, Shirin; Sniadecki, Nathan J.

2011-01-01

Coagulation involves a complex set of events that are important in maintaining hemostasis. Biochemical interactions are classically known to regulate the hemostatic process, but recent evidence has revealed that mechanical interactions between platelets and their surroundings can also play a substantial role. Investigations into platelet mechanobiology have been challenging however, due to the small dimensions of platelets and their glycoprotein receptors. Platelet researchers have recently turned to microfabricated devices to control these physical, nanometer-scale interactions with a higher degree of precision. These approaches have enabled exciting, new insights into the molecular and biomechanical factors that affect platelets in clot formation. In this review, we highlight the new tools used to understand platelet mechanobiology and the roles of adhesion, shear flow, and retraction forces in clot formation. PMID:22272117

Counting RG flows

DOE PAGES

Gukov, Sergei

2016-01-05

Here, interpreting renormalization group flows as solitons interpolating between different fixed points, we ask various questions that are normally asked in soliton physics but not in renormalization theory. Can one count RG flows? Are there different "topological sectors" for RG flows? What is the moduli space of an RG flow, and how does it compare to familiar moduli spaces of (supersymmetric) dowain walls? Analyzing these questions in a wide variety of contexts -- from counting RG walls to AdS/CFT correspondence -- will not only provide favorable answers, but will also lead us to a unified general framework that is powerfulmore » enough to account for peculiar RG flows and predict new physical phenomena. Namely, using Bott's version of Morse theory we relate the topology of conformal manifolds to certain properties of RG flows that can be used as precise diagnostics and "topological obstructions" for the strong form of the C-theorem in any dimension. Moreover, this framework suggests a precise mechanism for how the violation of the strong C-theorem happens and predicts "phase transitions" along the RG flow when the topological obstruction is non-trivial. Along the way, we also find new conformal manifolds in well-known 4d CFT's and point out connections with the superconformal index and classifying spaces of global symmetry groups.« less

Research on single-chip microcomputer controlled rotating magnetic field mineralization model

NASA Astrophysics Data System (ADS)

Li, Yang; Qi, Yulin; Yang, Junxiao; Li, Na

2017-08-01

As one of the method of selecting ore, the magnetic separation method has the advantages of stable operation, simple process flow, high beneficiation efficiency and no chemical environment pollution. But the existing magnetic separator are more mechanical, the operation is not flexible, and can not change the magnetic field parameters according to the precision of the ore needed. Based on the existing magnetic separator is mechanical, the rotating magnetic field can be used for single chip microcomputer control as the research object, design and trial a rotating magnetic field processing prototype, and through the single-chip PWM pulse output to control the rotation of the magnetic field strength and rotating magnetic field speed. This method of using pure software to generate PWM pulse to control rotary magnetic field beneficiation, with higher flexibility, accuracy and lower cost, can give full play to the performance of single-chip.

[An experimental study of the computer-controlled equipment for delivering volatile anesthetic agent].

PubMed

Sun, B; Li, W Z; Yue, Y; Jiang, C W; Xiao, L Y

2001-11-01

Our newly-designed computer-controlled equipment for delivering volatile anesthetic agent uses the subminiature singlechip processor as the central controlling unit. The variables, such as anesthesia method, anesthetic agent, the volume of respiratory loop, age of patient, sex, height, weight, environment temperature and the grade of ASA are all input from the keyboard. The anesthetic dosage, calculated by the singlechip processor, is converted into the signals controlling the pump to accurately deliver anesthetic agent into respiratory loop. We have designed an electrocircuit for the equipment to detect the status of the pump's operation, so we can assure of the safety and the stability of the equipment. The output precision of the equipment, with a good anti-jamming capability, is 1-2% for high flow anesthesia and 1-5% for closed-circuit anesthesia and its self-detecting working is reliable.

The ASLOTS concept: An interactive, adaptive decision support concept for Final Approach Spacing of Aircraft (FASA). FAA-NASA Joint University Program

NASA Technical Reports Server (NTRS)

Simpson, Robert W.

1993-01-01

This presentation outlines a concept for an adaptive, interactive decision support system to assist controllers at a busy airport in achieving efficient use of multiple runways. The concept is being implemented as a computer code called FASA (Final Approach Spacing for Aircraft), and will be tested and demonstrated in ATCSIM, a high fidelity simulation of terminal area airspace and airport surface operations. Objectives are: (1) to provide automated cues to assist controllers in the sequencing and spacing of landing and takeoff aircraft; (2) to provide the controller with a limited ability to modify the sequence and spacings between aircraft, and to insert takeoffs and missed approach aircraft in the landing flows; (3) to increase spacing accuracy using more complex and precise separation criteria while reducing controller workload; and (4) achieve higher operational takeoff and landing rates on multiple runways in poor visibility.

Precision increase in electric drive speed loop of robotic complexes and process lines

NASA Astrophysics Data System (ADS)

Tulegenov, E.; Imanova, A. A.; Platonov, V. V.

2018-05-01

The article presents the principles of synthesis of control structures for highprecision electric drives of robotic complexes and manipulators. It has been theoretically shown and experimentally confirmed that improved characteristics of speed maintenance in the zone of significant overloads are achieved in systems of series excitation. They are achieved due to the redistribution of control signals both in the zone of setting the armature current and in the excitation currents. At the same time, the characteristic of the electromagnetic torque becomes linear because the demagnetizing effect of the armature response is compensated by the setting of the excitation current. It is recommended in those cases when it is necessary to extend the range of speed control with a significant reduction in load to apply structures with two-zone speed control. The regulation of the weakening of the excitation flow is more convenient as a function of the voltage in the armature windings.

A novel jet-based nano-hydroxyapatite patterning technique for osteoblast guidance

PubMed Central

Li, Xiang; Koller, Garrit; Huang, Jie; Di Silvio, Lucy; Renton, Tara; Esat, Minoo; Bonfield, William; Edirisinghe, Mohan

2010-01-01

Surface topography is well known to play a crucial role in influencing cellular responses to an implant material and is therefore important in bone tissue regeneration. A novel jet-based patterning technique, template-assisted electrohydrodynamic atomization spraying, was recently devised to control precisely the surface structure as well as its dimensions. In the present study, a detailed investigation of this patterning process was carried out. A range of nano-hydroxyapatite (nHA) line-shaped patterns <20 µm in width were successfully deposited on a commercially pure Ti surface by controlling the flow of an nHA suspension in an electric field. In vitro studies showed that the nHA patterns generated are capable of regulating the human osteoblast cell attachment and orientation. PMID:19493897

Phase Grouping of Larmor Electrons by a Synchronous Wave in Controlled Magnetrons

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

Kazakevich, G.; Johnson, R.; Lebedev, V.

A simplified analytical model based on the charge drift approximation has been developed. It considers the resonant interaction of the synchronous wave with the flow of Larmor electrons in a magnetron. The model predicts stable coherent generation of the tube above and below the threshold of self-excitation. This occurs if the magnetron is driven by a sufficient resonant injected signal (up to -10 dB). The model substantiates precise stability, high efficiency and low noise at the range of the magnetron power control over 10 dB by variation of the magnetron current. The model and the verifying experiments with 2.45 GHz,more » 1 kW magnetrons are discussed.« less

Ligament flow during drop-on-demand inkjet printing of bioink containing living cells

NASA Astrophysics Data System (ADS)

Zhang, Mengyun; Krishnamoorthy, Srikumar; Song, Hongtao; Zhang, Zhengyi; Xu, Changxue

2017-03-01

Organ printing utilizes tissue spheroids or filaments as building blocks to fabricate three-dimensional (3D) functional tissues and organs based on a layer-by-layer manufacturing mechanism. These fabricated tissues and organs are envisioned as alternatives to replace the damaged human tissues and organs, which is emerging as a promising solution to solve the organ donor shortage problem being faced all over the world. Inkjetting, one of the key technologies in organ printing, has been widely developed because of its moderate fabrication cost, good process controllability, and scale-up potentials. There are several key steps towards inkjet-based organ printing: generation of droplets from bioink, fabrication of 3D cellular structures, and post-printing tissue fusion and maturation. The droplet formation process is the first step, affecting the overall feasibility of the envisioned organ printing technology. This paper focuses on the ligament flow of the droplet formation process during inkjet printing of bioink containing living cells and its corresponding effect on post-printing cell viability and cell distribution. It is found that (1) two types of ligament flow are observed: at 30 V (Type I), the ligament flow has two different directions at the locations near the nozzle orifice and the forming droplet; at 60 V (Type II), the ligament flow directions are the same at both locations; (2) compared to Type II, fewer cells are ejected into the primary droplets in Type I, because some cells move back into the nozzle driven by the ligament flow in the positive z direction; and (3) cell viability in both Type I and Type II is around 90% without a significant difference. The resulting knowledge will benefit precise control of printing dynamics during inkjet printing of viscoelastic bioink for 3D biofabrication applications.

Effects of solvent evaporation conditions on solvent vapor annealed cylinder-forming block polymer thin films

NASA Astrophysics Data System (ADS)

Grant, Meagan; Jakubowski, William; Nelson, Gunnar; Drapes, Chloe; Baruth, A.

Solvent vapor annealing is a less time and energy intensive method compared to thermal annealing, to direct the self-assembly of block polymer thin films. Periodic nanostructures have applications in ultrafiltration, magnetic arrays, or other structures with nanometer dimensions, driving its continued interest. Our goal is to create thin films with hexagonally packed, perpendicular aligned cylinders of poly(lactide) in a poly(styrene) matrix that span the thickness of the film with low anneal times and low defect densities, all with high reproducibility, where the latter is paramount. Through the use of our computer-controlled, pneumatically-actuated, purpose-built solvent vapor annealing chamber, we have the ability to monitor and control vapor pressure, solvent concentration within the film, and solvent evaporation rate with unprecedented precision and reliability. Focusing on evaporation, we report on two previously unexplored areas, chamber pressure during solvent evaporation and the flow rate of purging gas aiding the evaporation. We will report our exhaustive results following atomic force microscopy analysis of films exposed to a wide range of pressures and flow rates. Reliably achieving well-ordered films, while occurring within a large section of this parameter space, was correlated with high-flow evaporation rates and low chamber pressures. These results have significant implications on other methods of solvent annealing, including ``jar'' techniques.

The perceptual control of goal-directed locomotion: a common control architecture for interception and navigation?

PubMed

Chardenon, A; Montagne, G; Laurent, M; Bootsma, R J

2004-09-01

Intercepting a moving object while locomoting is a highly complex and demanding ability. Notwithstanding the identification of several informational candidates, the role of perceptual variables in the control process underlying such skills remains an open question. In this study we used a virtual reality set-up for studying locomotor interception of a moving ball. The subject had to walk along a straight path and could freely modify forward velocity, if necessary, in order to intercept-with the head-a ball moving along a straight path that led it to cross the agent's displacement axis. In a series of experiments we manipulated a local (ball size) and a global (focus of expansion) component of the visual flow but also the egocentric orientation of the ball. The experimental observations are well captured by a dynamic model linking the locomotor acceleration to properties of both global flow and egocentric direction. More precisely the changes in locomotor velocity depend on a linear combination of the change in bearing angle and the change in egocentric orientation, allowing the emergence of adaptive behavior under a variety of circumstances. We conclude that the mechanisms underlying the control of different goal-directed locomotion tasks (i.e. steering and interceptive tasks) could share a common architecture.

Semiautomated solid-phase extraction manifold with a solvent-level sensor.

PubMed

Orlando, R M; Rath, S; Rohwedder, J J R

2013-11-15

A semiautomated solid-phase extraction manifold for multiple extractions is presented. The manifold utilizes commercial solid-phase syringe cartridges and automatically introduces and elutes all the solvents during the extraction, reducing the typical workload and stress of the analyst. The manifold consists of a peristaltic pump with solenoid valves in a flow circuit that contains transmissive photomicrosensors. The photomicrosensors were used to control the solvent dispenser and the solvent level inside the cartridge. As solvent-level sensors, the photomicrosensors determined the exact time the solvent reached the top frit to avoid sorbent drying and accurately perform the solvent exchange. The repeatability of the manifold to introduce a particular volume of solvent into the cartridges was measured, and the precisions were between 0.05 and 2.89% (RSD). To evaluate the manifold, the amount of two fluoroquinolones in a fortified blank milk sample was determined. The results of the intra- and inter-day precision of multiple extractions from the fortified milk samples resulted in precisions better than 9.0% (RSD) and confirmed that the arrangement of the semiautomated manifold could adequately be used in solid-phase extraction with commercial cartridges. Copyright © 2013 Elsevier B.V. All rights reserved.

Ontology-based coupled optimisation design method using state-space analysis for the spindle box system of large ultra-precision optical grinding machine

NASA Astrophysics Data System (ADS)

Wang, Qianren; Chen, Xing; Yin, Yuehong; Lu, Jian

2017-08-01

With the increasing complexity of mechatronic products, traditional empirical or step-by-step design methods are facing great challenges with various factors and different stages having become inevitably coupled during the design process. Management of massive information or big data, as well as the efficient operation of information flow, is deeply involved in the process of coupled design. Designers have to address increased sophisticated situations when coupled optimisation is also engaged. Aiming at overcoming these difficulties involved in conducting the design of the spindle box system of ultra-precision optical grinding machine, this paper proposed a coupled optimisation design method based on state-space analysis, with the design knowledge represented by ontologies and their semantic networks. An electromechanical coupled model integrating mechanical structure, control system and driving system of the motor is established, mainly concerning the stiffness matrix of hydrostatic bearings, ball screw nut and rolling guide sliders. The effectiveness and precision of the method are validated by the simulation results of the natural frequency and deformation of the spindle box when applying an impact force to the grinding wheel.

Uncertainty of the peak flow reconstruction of the 1907 flood in the Ebro River in Xerta (NE Iberian Peninsula)

NASA Astrophysics Data System (ADS)

Ruiz-Bellet, Josep Lluís; Castelltort, Xavier; Balasch, J. Carles; Tuset, Jordi

2017-02-01

There is no clear, unified and accepted method to estimate the uncertainty of hydraulic modelling results. In historical floods reconstruction, due to the lower precision of input data, the magnitude of this uncertainty could reach a high value. With the objectives of giving an estimate of the peak flow error of a typical historical flood reconstruction with the model HEC-RAS and of providing a quick, simple uncertainty assessment that an end user could easily apply, the uncertainty of the reconstructed peak flow of a major flood in the Ebro River (NE Iberian Peninsula) was calculated with a set of local sensitivity analyses on six input variables. The peak flow total error was estimated at ±31% and water height was found to be the most influential variable on peak flow, followed by Manning's n. However, the latter, due to its large uncertainty, was the greatest contributor to peak flow total error. Besides, the HEC-RAS resulting peak flow was compared to the ones obtained with the 2D model Iber and with Manning's equation; all three methods gave similar peak flows. Manning's equation gave almost the same result than HEC-RAS. The main conclusion is that, to ensure the lowest peak flow error, the reliability and precision of the flood mark should be thoroughly assessed.

Generation and precise control of dynamic biochemical gradients for cellular assays

NASA Astrophysics Data System (ADS)

Saka, Yasushi; MacPherson, Murray; Giuraniuc, Claudiu V.

2017-03-01

Spatial gradients of diffusible signalling molecules play crucial roles in controlling diverse cellular behaviour such as cell differentiation, tissue patterning and chemotaxis. In this paper, we report the design and testing of a microfluidic device for diffusion-based gradient generation for cellular assays. A unique channel design of the device eliminates cross-flow between the source and sink channels, thereby stabilizing gradients by passive diffusion. The platform also enables quick and flexible control of chemical concentration that makes highly dynamic gradients in diffusion chambers. A model with the first approximation of diffusion and surface adsorption of molecules recapitulates the experimentally observed gradients. Budding yeast cells cultured in a gradient of a chemical inducer expressed a reporter fluorescence protein in a concentration-dependent manner. This microfluidic platform serves as a versatile prototype applicable to a broad range of biomedical investigations.

Double-Balloon-Assisted n-Butyl-2-Cyanoacrylate Embolization of Intrahepatic Arterioportal Shunt Prior to Chemoembolization of Hepatocellular Carcinoma

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

Takao, Hidemasa, E-mail: takaoh-tky@umin.ac.jp; Shibata, Eisuke; Ohtomo, Kuni

A case of multiple hepatocellular carcinomas with a severe intrahepatic arterioportal shunt that was successfully embolized with n-butyl-2-cyanoacrylate with coaxial double-balloon occlusion prior to transcatheter arterial chemoembolization is presented. A proximal balloon positioned at the proper hepatic artery was used for flow control, and a coaxial microballoon, positioned in the closest of three arterial feeding branches to the arterioportal shunt, was used to control the delivery of n-butyl-2-cyanoacrylate. This coaxial double-balloon technique can prevent proximal embolization and distal migration of n-butyl-2-cyanoacrylate and enable precise control of the distribution of n-butyl-2-cyanoacrylate. It could also be applicable to n-butyl-2-cyanoacrylate embolization for othermore » than intrahepatic arterioportal shunt.« less

Closed-loop control of renal perfusion pressure in physiological experiments.

PubMed

Campos-Delgado, D U; Bonilla, I; Rodríguez-Martínez, M; Sánchez-Briones, M E; Ruiz-Hernández, E

2013-07-01

This paper presents the design, experimental modeling, and control of a pump-driven renal perfusion pressure (RPP)-regulatory system to implement precise and relatively fast RPP regulation in rats. The mechatronic system is a simple, low-cost, and reliable device to automate the RPP regulation process based on flow-mediated occlusion. Hence, the regulated signal is the RPP measured in the left femoral artery of the rat, and the manipulated variable is the voltage applied to a dc motor that controls the occlusion of the aorta. The control system is implemented in a PC through the LabView software, and a data acquisition board NI USB-6210. A simple first-order linear system is proposed to approximate the dynamics in the experiment. The parameters of the model are chosen to minimize the error between the predicted and experimental output averaged from eight input/output datasets at different RPP operating conditions. A closed-loop servocontrol system based on a pole-placement PD controller plus dead-zone compensation was proposed for this purpose. First, the feedback structure was validated in simulation by considering parameter uncertainty, and constant and time-varying references. Several experimental tests were also conducted to validate in real time the closed-loop performance for stepwise and fast switching references, and the results show the effectiveness of the proposed automatic system to regulate the RPP in the rat, in a precise, accurate (mean error less than 2 mmHg) and relatively fast mode (10-15 s of response time).

High Power Helicon Plasma Source for Plasma Processing

NASA Astrophysics Data System (ADS)

Prager, James; Ziemba, Timothy; Miller, Kenneth E.

2015-09-01

Eagle Harbor Technologies (EHT), Inc. is developing a high power helicon plasma source. The high power nature and pulsed neutral gas make this source unique compared to traditional helicon source. These properties produce a plasma flow along the magnetic field lines, and therefore allow the source to be decoupled from the reaction chamber. Neutral gas can be injected downstream, which allows for precision control of the ion-neutral ratio at the surface of the sample. Although operated at high power, the source has demonstrated very low impurity production. This source has applications to nanoparticle productions, surface modification, and ionized physical vapor deposition.

Methods of and apparatus for levitating an eddy current probe

DOEpatents

Stone, William J.

1988-05-03

An eddy current probe is supported against the force of gravity with an air earing while being urged horizontally toward the specimen being examined by a spring and displaced horizontally against the force of the spring pneumatically. The pneumatic displacement is accomplished by flowing air between a plenum chamber fixed with respect to the probe and the surface of the specimen. In this way, the surface of the specimen can be examined without making mechanical contact therewith while precisely controlling the distance at which the probe stands-off from the surface of the specimen.

Oxygen-Mass-Flow Calibration Cell

NASA Technical Reports Server (NTRS)

Martin, Robert E.

1996-01-01

Proposed calibration standard for mass flow rate of oxygen based on conduction of oxygen ions through solid electrolyte membrane made of zirconia and heated to temperature of 1,000 degrees C. Flow of oxygen ions proportional to applied electric current. Unaffected by variations in temperature and pressure, and requires no measurement of volume. Calibration cell based on concept used to calibrate variety of medical and scientific instruments required to operate with precise rates of flow of oxygen.

A new model for turbidity current behavior based on integration of flow monitoring and precision coring in a submarine canyon

USGS Publications Warehouse

Symons, William O.; Sumner, Esther J.; Paull, Charles K.; Cartigny, Matthieu J.B.; Xu, Jingping; Maier, Katherine L.; Lorenson, Thomas; Talling, Peter J.

2017-01-01

Submarine turbidity currents create some of the largest sediment accumulations on Earth, yet there are few direct measurements of these flows. Instead, most of our understanding of turbidity currents results from analyzing their deposits in the sedimentary record. However, the lack of direct flow measurements means that there is considerable debate regarding how to interpret flow properties from ancient deposits. This novel study combines detailed flow monitoring with unusually precisely located cores at different heights, and multiple locations, within the Monterey submarine canyon, offshore California, USA. Dating demonstrates that the cores include the time interval that flows were monitored in the canyon, albeit individual layers cannot be tied to specific flows. There is good correlation between grain sizes collected by traps within the flow and grain sizes measured in cores from similar heights on the canyon walls. Synthesis of flow and deposit data suggests that turbidity currents sourced from the upper reaches of Monterey Canyon comprise three flow phases. Initially, a thin (38–50 m) powerful flow in the upper canyon can transport, tilt, and break the most proximal moorings and deposit chaotic sands and gravel on the canyon floor. The initially thin flow front then thickens and deposits interbedded sands and silty muds on the canyon walls as much as 62 m above the canyon floor. Finally, the flow thickens along its length, thus lofting silty mud and depositing it at greater altitudes than the previous deposits and in excess of 70 m altitude.

Precision digital control systems

NASA Astrophysics Data System (ADS)

Vyskub, V. G.; Rozov, B. S.; Savelev, V. I.

This book is concerned with the characteristics of digital control systems of great accuracy. A classification of such systems is considered along with aspects of stabilization, programmable control applications, digital tracking systems and servomechanisms, and precision systems for the control of a scanning laser beam. Other topics explored are related to systems of proportional control, linear devices and methods for increasing precision, approaches for further decreasing the response time in the case of high-speed operation, possibilities for the implementation of a logical control law, and methods for the study of precision digital control systems. A description is presented of precision automatic control systems which make use of electronic computers, taking into account the existing possibilities for an employment of computers in automatic control systems, approaches and studies required for including a computer in such control systems, and an analysis of the structure of automatic control systems with computers. Attention is also given to functional blocks in the considered systems.

New fully automated software for assessment of brachial artery flow- mediated dilation with advantages of continuous measurement.

PubMed

Ercan, Ertuğrul; Kırılmaz, Bahadır; Kahraman, İsmail; Bayram, Vildan; Doğan, Hüseyin

2012-11-01

Flow-mediated dilation (FMD) is used to evaluate endothelial functions. Computer-assisted analysis utilizing edge detection permits continuous measurements along the vessel wall. We have developed a new fully automated software program to allow accurate and reproducible measurement. FMD has been measured and analyzed in 18 coronary artery disease (CAD) patients and 17 controls both by manually and by the software developed (computer supported) methods. The agreement between methods was assessed by Bland-Altman analysis. The mean age, body mass index and cardiovascular risk factors were higher in CAD group. Automated FMD% measurement for the control subjects was 18.3±8.5 and 6.8±6.5 for the CAD group (p=0.0001). The intraobserver and interobserver correlation for automated measurement was high (r=0.974, r=0.981, r=0.937, r=0.918, respectively). Manual FMD% at 60th second was correlated with automated FMD % (r=0.471, p=0.004). The new fully automated software© can be used to precise measurement of FMD with low intra- and interobserver variability than manual assessment.

Oxidative coupling of methane using inorganic membrane reactor

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

Ma, Y.H.; Moser, W.R.; Dixon, A.G.

1995-12-31

The goal of this research is to improve the oxidative coupling of methane in a catalytic inorganic membrane reactor. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and relatively higher yields than in fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gasmore » phase reactions, which are believed to be a main route for formation of CO{sub x} products. Such gas phase reactions are a cause for decreased selectivity in oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Modeling work which aimed at predicting the observed experimental trends in porous membrane reactors was also undertaken in this research program.« less

Harnessing wake vortices for efficient collective swimming via deep reinfrcement learning

NASA Astrophysics Data System (ADS)

Verma, Siddartha; Novati, Guido; Koumoutsakos, Petros; ChairComputing Science Team

2017-11-01

Collective motion may bestow evolutionary advantages to a number of animal species. Soaring flocks of birds, teeming swarms of insects, and swirling masses of schooling fish, all to some extent enjoy anti-predator benefits, increased foraging success, and enhanced problem-solving abilities. Coordinated activity may also provide energetic benefits, as in the case of large groups of fish where swimmers exploit unsteady flow-patterns generated in the wake. Both experimental and computational investigations of such scenarios are hampered by difficulties associated with studying multiple swimmers. Consequentially, the precise energy-saving mechanisms at play remain largely unknown. We combine high-fidelity numerical simulations of multiple, self propelled swimmers with novel deep reinforcement learning algorithms to discover optimal ways for swimmers to interact with unsteady wakes, in a fully unsupervised manner. We identify optimal flow-interaction strategies devised by the resulting autonomous swimmers, and use it to formulate an effective control-logic. We demonstrate, via 3D simulations of controlled groups that swimmers exploiting the learned strategy exhibit a significant reduction in energy-expenditure. ERC Advanced Investigator Award 341117.

Combining Whispering-Gallery Mode Optical Biosensors with Microfluidics for Real-Time Detection of Protein Secretion from Living Cells in Complex Media.

PubMed

Chen, Ying-Jen; Schoeler, Ulrike; Huang, Chung-Hsuan Benjamin; Vollmer, Frank

2018-05-01

The noninvasive monitoring of protein secretion of cells responding to drug treatment is an effective and essential tool in latest drug development and for cytotoxicity assays. In this work, a surface functionalization method is demonstrated for specific detection of protein released from cells and a platform that integrates highly sensitive optical devices, called whispering-gallery mode biosensors, with precise microfluidics control to achieve label-free and real-time detection. Cell biomarker release is measured in real time and with nanomolar sensitivity. The surface functionalization method allows for antibodies to be immobilized on the surface for specific detection, while the microfluidics system enables detection in a continuous flow with a negligible compromise between sensitivity and flow control over stabilization and mixing. Cytochrome c detection is used to illustrate the merits of the system. Jurkat cells are treated with the toxin staurosporine to trigger cell apoptosis and cytochrome c released into the cell culture medium is monitored via the newly invented optical microfluidic platform. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fuzzy neural network for flow estimation in sewer systems during wet weather.

PubMed

Shen, Jun; Shen, Wei; Chang, Jian; Gong, Ning

2006-02-01

Estimation of the water flow from rainfall intensity during storm events is important in hydrology, sewer system control, and environmental protection. The runoff-producing behavior of a sewer system changes from one storm event to another because rainfall loss depends not only on rainfall intensities, but also on the state of the soil and vegetation, the general condition of the climate, and so on. As such, it would be difficult to obtain a precise flowrate estimation without sufficient a priori knowledge of these factors. To establish a model for flow estimation, one can also use statistical methods, such as the neural network STORMNET, software developed at Lyonnaise des Eaux, France, analyzing the relation between rainfall intensity and flowrate data of the known storm events registered in the past for a given sewer system. In this study, the authors propose a fuzzy neural network to estimate the flowrate from rainfall intensity. The fuzzy neural network combines four STORMNETs and fuzzy deduction to better estimate the flowrates. This study's system for flow estimation can be calibrated automatically by using known storm events; no data regarding the physical characteristics of the drainage basins are required. Compared with the neural network STORMNET, this method reduces the mean square error of the flow estimates by approximately 20%. Experimental results are reported herein.

Polarization selective phase-change nanomodulator

PubMed Central

Appavoo, Kannatassen; Haglund Jr., Richard F.

2014-01-01

Manipulating optical signals below the diffraction limit is crucial for next-generation data-storage and telecommunication technologies. Although controlling the flow of light around nanoscale waveguides was achieved over a decade ago, modulating optical signals at terahertz frequencies within nanoscale volumes remains a challenge. Since the physics underlying any modulator relies on changes in dielectric properties, the incorporation of strongly electron-correlated materials (SECMs) has been proposed because they can exhibit orders of magnitude changes in electrical and optical properties with modest thermal, electrical or optical trigger signals. Here we demonstrate a hybrid nanomodulator of deep sub-wavelength dimensions with an active volume of only 0.002 µm3 by spatially confining light on the nanometre length scale using a plasmonic nanostructure while simultaneously controlling the reactive near-field environment at its optical focus with a single, precisely positioned SECM nanostructure. Since the nanomodulator functionality hinges on this near-field electromagnetic interaction, the modulation is also selectively responsive to polarization. This architecture suggests one path for designing reconfigurable optoelectronic building blocks with responses that can be tailored with exquisite precision by varying size, geometry, and the intrinsic materials properties of the hybrid elements. PMID:25346427

Polarization selective phase-change nanomodulator

DOE PAGES

Appavoo, Kannatassen; Haglund Jr., Richard F.

2014-10-27

Manipulating optical signals below the diffraction limit is crucial for next-generation data-storage and telecommunication technologies. Although controlling the flow of light around nanoscale waveguides was achieved over a decade ago, modulating optical signals at terahertz frequencies within nanoscale volumes remains a challenge. Since the physics underlying any modulator relies on changes in dielectric properties, the incorporation of strongly electron-correlated materials (SECMs) has been proposed because they can exhibit orders of magnitude changes in electrical and optical properties with modest thermal, electrical or optical trigger signals. Here we demonstrate a hybrid nanomodulator of deep sub-wavelength dimensions with an active volume ofmore » only 0.002 µm 3 by spatially confining light on the nanometre length scale using a plasmonic nanostructure while simultaneously controlling the reactive near-field environment at its optical focus with a single, precisely positioned SECM nanostructure. Since the nanomodulator functionality hinges on this near-field electromagnetic interaction, the modulation is also selectively responsive to polarization. Lastly, this architecture suggests one path for designing reconfigurable optoelectronic building blocks with responses that can be tailored with exquisite precision by varying size, geometry, and the intrinsic materials properties of the hybrid elements.« less

Theoretical insights into multiscale electronic processes in organic photovoltaics

NASA Astrophysics Data System (ADS)

Tretiak, Sergei

Present day electronic devices are enabled by design and implementation of precise interfaces that control the flow of charge carriers. This requires robust and predictive multiscale approaches for theoretical description of underlining complex phenomena. Combined with thorough experimental studies such approaches provide a reliable estimate of physical properties of nanostructured materials and enable a rational design of devices. From this perspective I will discuss first principle modeling of small-molecule bulk-heterojunction organic solar cells and push-pull chromophores for tunable-color organic light emitters. The emphasis is on electronic processes involving intra- and intermolecular energy or charge transfer driven by strong electron-phonon coupling inherent to pi-conjugated systems. Finally I will describe how precise manipulation and control of organic-organic interfaces in a photovoltaic device can increase its power conversion efficiency by 2-5 times in a model bilayer system. Applications of these design principles to practical architectures like bulk heterojunction devices lead to an enhancement in power conversion efficiency from 4.0% to 7.0%. These interface manipulation strategies are universally applicable to any donor-acceptor interface, making them both fundamentally interesting and technologically important for achieving high efficiency organic electronic devices.

Using femtosecond laser to fabricate highly precise interior three-dimensional microstructures in polymeric flow chip

PubMed Central

Lee, Chia-Yu; Chang, Ting-Chou; Wang, Shau-Chun; Chien, Chih-Wei; Cheng, Chung-Wei

2010-01-01

This paper reports using femtosecond laser marker to fabricate the three-dimensional interior microstructures in one closed flow channel of plastic substrate. Strip-like slots in the dimensions of 800 μm×400 μm×65 μm were ablated with pulse Ti:sapphire laser at 800 nm (pulse duration of ∼120 fs with 1 kHz repetition rate) on acrylic slide. After ablation, defocused beams were used to finish the surface of microstructures. Having finally polished with sonication, the laser fabricated structures are highly precise with the arithmetic roughness of 1.5 and 4.5 nm. Fabricating such highly precise microstructures cannot be accomplished with nanosecond laser marking or other mechanical drilling methods. In addition, since laser ablation can directly engrave interior microstructures in one closed chip, glue smearing problems to damage molded microstructures possibly to occur during the chip sealing procedures can be avoided too. PMID:21079695

Using femtosecond laser to fabricate highly precise interior three-dimensional microstructures in polymeric flow chip.

PubMed

Lee, Chia-Yu; Chang, Ting-Chou; Wang, Shau-Chun; Chien, Chih-Wei; Cheng, Chung-Wei

2010-10-18

This paper reports using femtosecond laser marker to fabricate the three-dimensional interior microstructures in one closed flow channel of plastic substrate. Strip-like slots in the dimensions of 800 μm×400 μm×65 μm were ablated with pulse Ti:sapphire laser at 800 nm (pulse duration of ∼120 fs with 1 kHz repetition rate) on acrylic slide. After ablation, defocused beams were used to finish the surface of microstructures. Having finally polished with sonication, the laser fabricated structures are highly precise with the arithmetic roughness of 1.5 and 4.5 nm. Fabricating such highly precise microstructures cannot be accomplished with nanosecond laser marking or other mechanical drilling methods. In addition, since laser ablation can directly engrave interior microstructures in one closed chip, glue smearing problems to damage molded microstructures possibly to occur during the chip sealing procedures can be avoided too.

Investigation of flow in data rack

NASA Astrophysics Data System (ADS)

Manoch, Lukáš; Nožička, Jiří; Pohan, Petr

2012-04-01

The main purpose of this paper was to set up a functioning numerical model of data rack verified by an experimental measurement. The verification of the numerical model was carried out by means of the PIV method (Particle Image Velocimetry). The numerical model was "found" while using the assumed and preset values from the experimental measurement which represent boundary conditions. The server model was conceived as a four-channel with a controlled flow rate without simulation of heat transfer. The flow rate in each channel was implemented by means of pressure loss. The numerical model was further used for simulation of several phases and configurations of data rack (21U rack space) fitted with two server workstations Dell Precision R5400. The flow field in the inlet of data rack in the front of the workstations were observed and evaluated in such a way that a 2U-dimensional free space between the workstations was being left and the remaining inlet space was blanked-off/fully opened. The results of this paper will serve for designing optimization treatment of data rack from the viewpoint of cooling efficiency both within the data rack and within the data center design.

Determination of mercury by multisyringe flow injection system with cold-vapor atomic absorption spectrometry.

PubMed

Leal, L O; Elsholz, O; Forteza, R; Cerdà, V

2006-07-28

A new software-controlled time-based multisyringe flow injection system for mercury determination by cold-vapor atomic absorption spectrometry is proposed. Precise known volumes of sample, reducing agent (1.1% SnCl2 in 3% HCl) and carrier (3% HCl) are dispensed into a gas-liquid separation cell with a multisyringe burette coupled with one three-way solenoid valve. An argon flow delivers the reduced mercury to the spectrometer. The optimization of the system was carried out testing reaction coils and gas-liquid separators of different design as well as changing parameters, such as sample and reagents volumes, reagent concentrations and carrier gas flow rate, among others. The analytical curves were obtained within the range 50-5000 ng L(-1). The detection limit (3sigma(b)/S) achieved is 5 ng L(-1). The relative standard deviation (R.S.D.) was 1.4%, evaluated from 16 successive injections of 250 ng L(-1) Hg standard solution. The injection and sample throughput per hour were 44 and 11, respectively. This technique was validated by means of solid and water reference materials with good agreement with the certified values and was successfully applied to fish samples.

Dynamic characteristics of hydrocarbon fuel within the channel at supercritical and pyrolysis condition

NASA Astrophysics Data System (ADS)

Yu, Bin; Zhou, Weixing; Qin, Jiang; Bao, Wen

2017-12-01

Regenerative cooling with fuel as the coolant is used in the scramjet engine. In order to grasp the dynamic characteristics of engine fuel supply processes, this article studies the dynamic characteristics of hydrocarbon fuel within the channel. A one-dimensional dynamic model was proved, the thermal energy storage effect, fuel volume effect and chemical dynamic effect have been considered in the model, the ordinary differential equations were solved using a 4th order Runge-Kutta method. The precision of the model was validated by three groups of experimental data. The effects of input signal, working condition, tube size on the dynamic characteristics of pressure, flow rate, temperature have been simulated. It is found that cracking reaction increased the compressibility of the fuel pyrolysis mixture and lead to longer responding time of outlet flow. The responding time of outlet flow can reach 3s when tube is 5m long which will greatly influence the control performance of the engine thrust system. Meanwhile, when the inlet flow rate appears the step change, the inlet pressure leads to overshoot, the overshoot can reach as much as 100%, such highly transient impulse will result in detrimental effect on fuel pump.

Multiple pathways for woody plant establishment on floodplains at local to regional scales

USGS Publications Warehouse

Cooper, D.J.; Andersen, D.C.; Chimner, Rodney A.

2003-01-01

1. The structure and functioning of riverine ecosystems is dependent upon regional setting and the interplay of hydrologic regime and geomorphologic processes. We used a retrospective analysis to study recruitment along broad, alluvial valley segments (parks) and canyon segments of the unregulated Yampa River and the regulated Green River in the upper Colorado River basin, USA. We precisely aged 811 individuals of Populus deltoides ssp. wislizenii (native) and Tamarix ramosissima (exotic) from 182 wooded patches and determined the elevation and character of the germination surface for each. We used logistic regression to relate recruitment events (presence or absence of cohort) to five flow and two weather parameters.2. Woody plant establishment occurred via multiple pathways at patch, reach and segment scales. Recruitment occurred through establishment on (1) vertically accreting bars in the unregulated alluvial valley, (2) high alluvial floodplain surfaces during rare large flood events, (3) vertically accreting channel margin deposits in canyon pools and eddies, (4) vertically accreting intermittent/abandoned channels, (5) low elevation gravel bars and debris fans in canyons during multi-year droughts, and (6) bars and channels formed prior to flow regulation on the dammed river during controlled flood events.3. The Yampa River's peak flow was rarely included in models estimating the likelihood that recruitment would occur in any year. Flow variability and the interannual pattern of flows, rather than individual large floods, control most establishment.4. Regulation of the Green River flow since 1962 has had different effects on woody vegetation recruitment in canyons and valleys. The current regime mimics drought in a canyon setting, accelerating Tamarix invasion whereas in valleys the ongoing geomorphic adjustment of the channel, combined with reduced flow variability, has nearly eliminated Populus establishment.5. A single year's flow or a particular pattern of flows over a sequence of years, whether natural or man-made, produces different recruitment opportunities in alluvial and canyon reaches, in diverse landforms within a particular river reach, and for Populus and Tamarix. The design of flows to restore riparian ecosystems must consider these multiple pathways and adjust the seasonal timing, magnitude and interannual frequency of flows to match the desired outcome.

Granular flow in a rotating drum: Experiments and theory

NASA Astrophysics Data System (ADS)

Hung, C. Y.; Stark, C. P.; Capart, H.; Li, L.; Smith, B.; Grinspun, E.

2015-12-01

Erosion at the base of a debris flow fundamentally controls how large the flow will become and how far it will travel. Experimental observations of this important phenomenon are rather limited, and this lack has led theoretical treatments to making ad hoc assumptions about the basal process. In light of this, we carried out a combination of laboratory experiments and theoretical analysis of granular flow in a rotating drum, a canonical example of steady grain motion in which entrainment rates can be precisely controlled. Our main result is that basal sediment is entrained as the velocity profile adjusts to imbalance in the flow of kinetic energy.Our experimental apparatus consisted of a 40cm-diameter drum, 4cm-deep, half-filled with 2.3mm grains. Rotation rates varied from 1-70 rpm. We varied the effective scale by varying effective gravity from 1g to 70g on a geotechnical centrifuge. The field of grain motion was recorded using high-speed video and mapped using particle tracking velocimetry. In tandem we developed a depth-averaged theory using balance equations for mass, momentum and kinetic energy. We assumed a linearized GDR Midi granular rheology [da Cruz, 2005] and a Coulomb friction law along the sidewalls [Jop et al., 2005]. A scaling analysis of our equations yields a dimensionless "entrainment number" En, which neatly parametrizes the flow geometry in the drum for a wide range of variables, e.g., rotation rate and effective gravity. At low En, the flow profile is planar and kinetic energy is balanced locally in the flow layer. At high En, the flow profile is sigmoidal (yin-yang shaped) and the kinetic energy is dominated by longitudinal, streamwise transfer. We observe different scaling behavior under each of these flow regimes, e.g., between En and kinetic energy, surface slope and flow depth. Our theory correctly predicts their scaling exponents and the value of En at which the regime transition takes place. We are also able to make corrections for Coriolis and dilation effects that improve the match between theory and experiment.

Flow cytometry as a method for the evaluation of raw material, product and process in the dairy industry.

PubMed

Ruszczyńska, A; Szteyn, J; Wiszniewska-Laszczych, A

2007-01-01

Producing dairy products which are safe for consumers requires the constant monitoring of the microbiological quality of raw material, the production process itself and the end product. Traditional methods, still a "gold standard", require a specialized laboratory working on recognized and validated methods. Obtaining results is time- and labor-consuming and do not allow rapid evaluation. Hence, there is a need for a rapid, precise method enabling the real-time monitoring of microbiological quality, and flow cytometry serves this function well. It is based on labeling cells suspended in a solution with fluorescent dyes and pumping them into a measurement zone where they are exposed to a precisely focused laser beam. This paper is aimed at presenting the possibilities of applying flow cytometry in the dairy industry.

Surveillance of hemodialysis vascular access with ultrasound vector flow imaging

NASA Astrophysics Data System (ADS)

Brandt, Andreas H.; Olesen, Jacob B.; Hansen, Kristoffer L.; Rix, Marianne; Jensen, Jørgen A.; Nielsen, Michael B.

2015-03-01

The aim of this study was prospectively to monitor the volume flow in patients with arteriovenous fistula (AVF) with the angle independent ultrasound technique Vector Flow Imaging (VFI). Volume flow values were compared with Ultrasound dilution technique (UDT). Hemodialysis patients need a well-functioning vascular access with as few complications as possible and preferred vascular access is an AVF. Dysfunction due to stenosis is a common complication, and regular monitoring of volume flow is recommended to preserve AVF patency. UDT is considered the gold standard for volume flow surveillance, but VFI has proven to be more precise, when performing single repeated instantaneous measurements. Three patients with AVF were monitored with UDT and VFI monthly for five months. A commercial ultrasound scanner with a 9 MHz linear array transducer with integrated VFI was used to obtain data. UDT values were obtained with Transonic HD03 Flow-QC Hemodialysis Monitor. Three independent measurements at each scan session were obtained with UDT and VFI each month. Average deviation of volume flow between UDT and VFI was 25.7 % (Cl: 16.7% to 34.7%) (p= 0.73). The standard deviation for all patients, calculated from the mean variance of each individual scan sessions, was 199.8 ml/min for UDT and 47.6 ml/min for VFI (p = 0.002). VFI volume flow values were not significantly different from the corresponding estimates obtained using UDT, and VFI measurements were more precise than UDT. The study indicates that VFI can be used for surveillance of volume flow.

Flow-Centric, Back-in-Time Debugging

NASA Astrophysics Data System (ADS)

Lienhard, Adrian; Fierz, Julien; Nierstrasz, Oscar

Conventional debugging tools present developers with means to explore the run-time context in which an error has occurred. In many cases this is enough to help the developer discover the faulty source code and correct it. However, rather often errors occur due to code that has executed in the past, leaving certain objects in an inconsistent state. The actual run-time error only occurs when these inconsistent objects are used later in the program. So-called back-in-time debuggers help developers step back through earlier states of the program and explore execution contexts not available to conventional debuggers. Nevertheless, even Back-in-Time Debuggers do not help answer the question, “Where did this object come from?” The Object-Flow Virtual Machine, which we have proposed in previous work, tracks the flow of objects to answer precisely such questions, but this VM does not provide dedicated debugging support to explore faulty programs. In this paper we present a novel debugger, called Compass, to navigate between conventional run-time stack-oriented control flow views and object flows. Compass enables a developer to effectively navigate from an object contributing to an error back-in-time through all the code that has touched the object. We present the design and implementation of Compass, and we demonstrate how flow-centric, back-in-time debugging can be used to effectively locate the source of hard-to-find bugs.

Palaeomagnetic refinement of the eruption ages of Holocene lava flows, and implications for the eruptive history of the Tongariro Volcanic Centre, New Zealand

NASA Astrophysics Data System (ADS)

Greve, Annika; Turner, Gillian M.; Conway, Chris E.; Townsend, Dougal B.; Gamble, John A.; Leonard, Graham S.

2016-11-01

We present a detailed palaeomagnetic study from 35 sites on Holocene lava flows of the Tongariro Volcanic Centre, central North Island, New Zealand. Prior to the study the eruption ages of these flows were constrained to within a few thousand years by recently published high-precision 40Ar/39Ar geochronological data and tephrostratigraphic controls. Correlation of flow mean palaeomagnetic directions with a recently published continuous sediment record from Lake Mavora, Fiordland, allows us to reduce the age uncertainty to 300-500 yr in some cases. Our refined ages significantly improve the chronology of Holocene effusive eruptions of the volcanoes of the Tongariro Volcanic Centre. For instance, differences in the palaeomagnetic directions recorded by lavas from the voluminous Iwikau and Rangataua members suggest that individual effusive periods lasted up to thousands of years and that these bursts have been irregularly spaced over time. While over the last few millennia the effusive eruptive activity from Mt Ruapehu has been relatively quiet, the very young age (200-500 BP) of a Red Crater sourced flow suggests that effusive activity around Mt Tongariro lasted into the past few centuries. This adds an important hazard context to the historical record, which has otherwise comprised frequent relatively small, tephra producing, explosive eruptions without the production of lava flows.

Tidal reversal and flow velocities using temperature and specific conductance in a small wetland creek

NASA Astrophysics Data System (ADS)

Eaton, Timothy T.

2016-11-01

Characterizing flow dynamics in very small tidal creeks is complicated and not well suited to methods developed for upland streams or coastal estuaries, due to low flows, bidirectionality and shallow waters. Simple instrumentation enables thermal and salinity signals to be used to observe flow directions and estimate velocities in these settings. Using multiple inexpensive sensors over 500 m along a tidally influenced wetland creek, I demonstrate how advection of temperature and specific conductance pulses reveal flood and ebb tides and the temporary reversal of flow by warmer, estuarine water from the receiving embayment. The sequential rise of temperature upstream was most evident under hot and dry conditions, after daily peak air temperatures of 25 °C or above, and was subdued or disrupted under cooler or rainy conditions in summertime. Changes in specific conductance at successive sites upstream were less susceptible to environmental influences and confirm tidal flood velocity of between 0.07 and 0.37 m/s. The tidally-induced flow reversal suggests that periodic high tide conditions can interfere with rapid dispersal of pollution discharges, such as from the combined sewer overflow (CSO) located upstream of the studied creek reach. This low-cost approach of temperature and specific conductance sensing in vegetated coastal wetlands where access, precise elevation control and creek discharge measurements are difficult, provides a simple way of tracking water masses when sufficient contrast exists between water sources.

Minimum data requirement for neural networks based on power spectral density analysis.

PubMed

Deng, Jiamei; Maass, Bastian; Stobart, Richard

2012-04-01

One of the most critical challenges ahead for diesel engines is to identify new techniques for fuel economy improvement without compromising emissions regulations. One technique is the precise control of air/fuel ratio, which requires the measurement of instantaneous fuel consumption. Measurement accuracy and repeatability for fuel rate is the key to successfully controlling the air/fuel ratio and real-time measurement of fuel consumption. The volumetric and gravimetric measurement principles are well-known methods for measurement of fuel consumption in internal combustion engines. However, the fuel flow rate measured by these methods is not suitable for either real-time control or real-time measurement purposes because of the intermittent nature of the measurements. This paper describes a technique that can be used to find the minimum data [consisting of data from just 2.5% of the non-road transient cycle (NRTC)] to solve the problem concerning discontinuous data of fuel flow rate measured using an AVL 733S fuel meter for a medium or heavy-duty diesel engine using neural networks. Only torque and speed are used as the input parameters for the fuel flow rate prediction. Power density analysis is used to find the minimum amount of the data. The results show that the nonlinear autoregressive model with exogenous inputs could predict the particulate matter successfully with R(2) above 0.96 using 2.5% NRTC data with only torque and speed as inputs.

Calibration of silicone rubber rods as passive samplers for pesticides at two different flow velocities: Modeling of sampling rates under water boundary layer and polymer control.

PubMed

Martin, Alexis; Margoum, Christelle; Jolivet, Antoine; Assoumani, Azziz; El Moujahid, Bachir; Randon, Jérôme; Coquery, Marina

2018-04-01

There is a need to determine time-weighted average concentrations of polar contaminants such as pesticides by passive sampling in environmental waters. Calibration data for silicone rubber-based passive samplers are lacking for this class of compounds. The calibration data, sampling rate (R s ), and partition coefficient between silicone rubber and water (K sw ) were precisely determined for 23 pesticides and 13 candidate performance reference compounds (PRCs) in a laboratory calibration system over 14 d for 2 water flow velocities, 5 and 20 cm s -1 . The results showed that an in situ exposure duration of 7 d left a silicone rubber rod passive sampler configuration in the linear or curvilinear uptake period for 19 of the pesticides studied. A change in the transport mechanism from polymer control to water boundary layer control was observed for pesticides with a log K sw of approximately 3.3. The PRC candidates were not fully relevant to correct the impact of water flow velocity on R s . We therefore propose an alternative method based on an overall resistance to mass transfer model to adjust R s from laboratory experiments to in situ hydrodynamic conditions. We estimated diffusion coefficients (D s ) and thickness of water boundary layer (δ w ) as adjustable model parameters. Log D s values ranged from -12.13 to -10.07 m 2  s -1 . The estimated δ w value showed a power function correlation with water flow velocity. Environ Toxicol Chem 2018;37:1208-1218. © 2017 SETAC. © 2017 SETAC.

Concentration gradient induced morphology evolution of silica nanostructure growth on photoresist-derived carbon micropatterns

NASA Astrophysics Data System (ADS)

Liu, Dan; Shi, Tielin; Xi, Shuang; Lai, Wuxing; Liu, Shiyuan; Li, Xiaoping; Tang, Zirong

2012-09-01

The evolution of silica nanostructure morphology induced by local Si vapor source concentration gradient has been investigated by a smart design of experiments. Silica nanostructure or their assemblies with different morphologies are obtained on photoresist-derived three-dimensional carbon microelectrode array. At a temperature of 1,000°C, rope-, feather-, and octopus-like nanowire assemblies can be obtained along with the Si vapor source concentration gradient flow. While at 950°C, stringlike assemblies, bamboo-like nanostructures with large joints, and hollow structures with smaller sizes can be obtained along with the Si vapor source concentration gradient flow. Both vapor-liquid-solid and vapor-quasiliquid-solid growth mechanisms have been applied to explain the diverse morphologies involving branching, connecting, and batch growth behaviors. The present approach offers a potential method for precise design and controlled synthesis of nanostructures with different features.

Self-powered enzyme micropumps

NASA Astrophysics Data System (ADS)

Sengupta, Samudra; Patra, Debabrata; Ortiz-Rivera, Isamar; Agrawal, Arjun; Shklyaev, Sergey; Dey, Krishna K.; Córdova-Figueroa, Ubaldo; Mallouk, Thomas E.; Sen, Ayusman

2014-05-01

Non-mechanical nano- and microscale pumps that function without the aid of an external power source and provide precise control over the flow rate in response to specific signals are needed for the development of new autonomous nano- and microscale systems. Here we show that surface-immobilized enzymes that are independent of adenosine triphosphate function as self-powered micropumps in the presence of their respective substrates. In the four cases studied (catalase, lipase, urease and glucose oxidase), the flow is driven by a gradient in fluid density generated by the enzymatic reaction. The pumping velocity increases with increasing substrate concentration and reaction rate. These rechargeable pumps can be triggered by the presence of specific analytes, which enables the design of enzyme-based devices that act both as sensor and pump. Finally, we show proof-of-concept enzyme-powered devices that autonomously deliver small molecules and proteins in response to specific chemical stimuli, including the release of insulin in response to glucose.

Control system of water flow and casting speed in continuous steel casting

NASA Astrophysics Data System (ADS)

Tirian, G. O.; Gheorghiu, C. A.; Hepuţ, T.; Chioncel, C.

2017-05-01

This paper presents the results of research based on real data taken from the installation process at Arcelor Mittal Hunedoara. Using Matlab Simulink an intelligent system is made that takes in data from the process and makes real time adjustments in the rate of flow of the cooling water and the speed of casting that eliminates fissures in the poured material from the secondary cooling of steel. Using Matlab Simulink simulation environment allowed for qualitative analysis for various real world situations. Thus, compared to the old method of approach for the problem of cracks forming in the crust of the steel in the continuous casting, this new method, proposed and developed, brings safety and precision in this complex process, thus removing any doubt on the existence or non-existence of cracks and takes the necessary steps to prevent and correct them.

Searching for order in atmospheric pressure plasma jets

NASA Astrophysics Data System (ADS)

Schäfer, Jan; Sigeneger, Florian; Šperka, Jiří; Rodenburg, Cornelia; Foest, Rüdiger

2018-01-01

The self-organized discharge behaviour occurring in a non-thermal radio-frequency plasma jet in rare gases at atmospheric pressure was investigated. The frequency of the azimuthal rotation of filaments in the active plasma volume and their inclination were measured along with the gas temperature under varying discharge conditions. The gas flow and heating were described theoretically by a three-dimensional hydrodynamic model. The rotation frequencies obtained by both methods qualitatively agree. The results demonstrate that the plasma filaments forming an inclination angle α with the axial gas velocity u z are forced to a transversal movement with the velocity {u}φ =\\tan (α )\\cdot {u}z, which is oriented in the inclination direction. Variations of {u}φ in the model reveal that the observed dynamics minimizes the energy loss due to convective heat transfer by the gas flow. The control of the self-organization regime motivates the application of the plasma jet for precise and reproducible material processing.

Development of an economical, autonomous pHstat system for culturing phytoplankton under steady state or dynamic conditions.

PubMed

Golda, Rachel L; Golda, Mark D; Hayes, Jacqueline A; Peterson, Tawnya D; Needoba, Joseph A

2017-05-01

Laboratory investigations of physiological processes in phytoplankton require precise control of experimental conditions. Chemostats customized to control and maintain stable pH levels (pHstats) are ideally suited for investigations of the effects of pH on phytoplankton physiology, for example in context of ocean acidification. Here we designed and constructed a simple, flexible pHstat system and demonstrated its operational capabilities under laboratory culture conditions. In particular, the system is useful for simulating natural cyclic pH variability within aquatic ecosystems, such as diel fluctuations that result from metabolic activity or tidal mixing in estuaries. The pHstat system operates in two modes: (1) static/set point pH, which maintains pH at a constant level, or (2) dynamic pH, which generates regular, sinusoidal pH fluctuations by systematically varying pH according to user-defined parameters. The pHstat is self-regulating through the use of interchangeable electronically controlled reagent or gas-mediated pH-modification manifolds, both of which feature flow regulation by solenoid valves. Although effective pH control was achieved using both liquid reagent additions and gas-mediated methods, the liquid manifold exhibited tighter control (±0.03pH units) of the desired pH than the gas manifold (±0.10pH units). The precise control provided by this pHstat system, as well as its operational flexibility will facilitate studies that examine responses by marine microbiota to fluctuations in pH in aquatic ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

A precise pointing nanopipette for single-cell imaging via electroosmotic injection.

PubMed

Lv, Jian; Qian, Ruo-Can; Hu, Yong-Xu; Liu, Shao-Chuang; Cao, Yue; Zheng, Yong-Jie; Long, Yi-Tao

2016-11-24

The precise transportation of fluorescent probes to the designated location in living cells is still a challenge. Here, we present a new addition to nanopipettes as a powerful tool to deliver fluorescent molecules to a given place in a single cell by electroosmotic flow, indicating favorable potential for further application in single-cell imaging.

Applications of low altitude photogrammetry for morphometry, displacements, and landform modeling

NASA Astrophysics Data System (ADS)

Gomez, F. G.; Polun, S. G.; Hickcox, K.; Miles, C.; Delisle, C.; Beem, J. R.

2016-12-01

Low-altitude aerial surveying is emerging as a tool that greatly improves the ease and efficiency of measuring landforms for quantitative geomorphic analyses. High-resolution, close-range photogrammetry produces dense, 3-dimensional point clouds that facilitate the construction of digital surface models, as well as a potential means of classifying ground targets using spatial structure. This study presents results from recent applications of UAS-based photogrammetry, including high resolution surface morphometry of a lava flow, repeat-pass applications to mass movements, and fault scarp degradation modeling. Depending upon the desired photographic resolution and the platform/payload flown, aerial photos are typically acquired at altitudes of 40 - 100 meters above the ground surface. In all cases, high-precision ground control points are key for accurate (and repeatable) orientation - relying on low-precision GPS coordinates (whether on the ground or geotags in the aerial photos) typically results in substantial rotations (tilt) of the reference frame. Using common ground control points between repeat surveys results in matching point clouds with RMS residuals better than 10 cm. In arid regions, the point cloud is used to assess lava flow surface roughness using multi-scale measurements of point cloud dimensionality. For the landslide study, the point cloud provides a basis for assessing possible displacements. In addition, the high resolution orthophotos facilitate mapping of fractures and their growth. For neotectonic applications, we compare fault scarp modeling results from UAV-derived point clouds versus field-based surveys (kinematic GPS and electronic distance measurements). In summary, there is a wide ranging toolbox of low-altitude aerial platforms becoming available for field geoscientists. In many instances, these tools will present convenience and reduced cost compared with the effort and expense to contract acquisitions of aerial imagery.

Fluid-flow-rate metrology: laboratory uncertainties and traceabilities

NASA Astrophysics Data System (ADS)

Mattingly, G. E.

1991-03-01

Increased concerns for improved fluid flowrate measurement are driving the fluid metering community-meter manufacturers and users alike-to search for better verification and documentation for their fluid measurements. These concerns affect both our domestic and international market places they permeate our technologies - aerospace chemical processes automotive bioengineering etc. They involve public health and safety and they impact our national defense. These concerns are based upon the rising value of fluid resources and products and the importance of critical material accountability. These values directly impact the accuracy needs of fluid buyers and sellers in custody transfers. These concerns impact the designers and operators of chemical process systems where control and productivity optimization depend critically upon measurement precision. Public health and safety depend upon the quality of numerous pollutant measurements - both liquid and gaseous. The performance testing of engines - both automotive and aircraft are critically based upon accurate fuel measurements - both liquid and oxidizer streams. Fluid flowrate measurements are established differently from counterparts in length and mass measurement systems because these have the benefits of " identity" standards. For rate measurement systems the metrology is based upon " derived standards" . These use facilities and transfer standards which are designed built characterized and used to constitute basic measurement capabilities and quantify performance - accuracy and precision. Because " identity standards" do not exist for flow measurements facsimiles or equivalents must

Etching radical controlled gas chopped deep reactive ion etching

DOEpatents

Olynick, Deidre; Rangelow, Ivo; Chao, Weilun

2013-10-01

A method for silicon micromachining techniques based on high aspect ratio reactive ion etching with gas chopping has been developed capable of producing essentially scallop-free, smooth, sidewall surfaces. The method uses precisely controlled, alternated (or chopped) gas flow of the etching and deposition gas precursors to produce a controllable sidewall passivation capable of high anisotropy. The dynamic control of sidewall passivation is achieved by carefully controlling fluorine radical presence with moderator gasses, such as CH.sub.4 and controlling the passivation rate and stoichiometry using a CF.sub.2 source. In this manner, sidewall polymer deposition thicknesses are very well controlled, reducing sidewall ripples to very small levels. By combining inductively coupled plasmas with controlled fluorocarbon chemistry, good control of vertical structures with very low sidewall roughness may be produced. Results show silicon features with an aspect ratio of 20:1 for 10 nm features with applicability to nano-applications in the sub-50 nm regime. By comparison, previous traditional gas chopping techniques have produced rippled or scalloped sidewalls in a range of 50 to 100 nm roughness.

Regimes of Two-Phase Flow in Short Rectangular Channel

NASA Astrophysics Data System (ADS)

Chinnov, Evgeny A.; Guzanov, Vladimir V.; Cheverda, Vyacheslav; Markovich, Dmitry M.; Kabov, Oleg A.

2009-08-01

Experimental study of two-phase flow in the short rectangular horizontal channel with height 440 μm has been performed. Characteristics of liquid motion inside the channel have been registered and measured by the Laser Induced Fluorescence technique. New information has allowed determining more precisely the characteristics of churn regime and boundaries between different regimes of two-phase flow. It was shown that formation of some two-phase flow regimes and transitions between them are determined by instability of the flow in the lateral parts of the channel.

Development of a New Fundamental Measuring Technique for the Accurate Measurement of Gas Flowrates by Means of Laser Doppler Anemometry

NASA Astrophysics Data System (ADS)

Dopheide, D.; Taux, G.; Krey, E.-A.

1990-01-01

In the Physikalisch-Technische Bundesanstalt (PTB), a research test facility for the accurate measurement of gas (volume and mass) flowrates has been set up in the last few years on the basis of a laser Doppler anemometer (LDA) with a view to directly measuring gas flowrates with a relative uncertainty of only 0,1%. To achieve this, it was necessary to develop laser Doppler anemometry into a precision measuring technique and to carry out detailed investigations on stationary low-turbulence nozzle flow. The process-computer controlled test facility covers the flowrate range from 100 to 4000 m3/h (~0,03 - 1,0 m3/s), any flowrate being measured directly, immediately and without staggered arrangement of several flow meters. After the development was completed, several turbine-type gas meters were calibrated and international comparisons carried out. The article surveys the most significant aspects of the work and provides an outlook on future developments with regard to the miniaturization of optical flow and flowrate sensors for industrial applications.

Integrated titer plate-injector head for microdrop array preparation, storage and transfer

DOEpatents

Swierkowski, Stefan P.

2000-01-01

An integrated titer plate-injector head for preparing and storing two-dimensional (2-D) arrays of microdrops and for ejecting part or all of the microdrops and inserting same precisely into 2-D arrays of deposition sites with micrometer precision. The titer plate-injector head includes integrated precision formed nozzles with appropriate hydrophobic surface features and evaporative constraints. A reusable pressure head with a pressure equalizing feature is added to the titer plate to perform simultaneous precision sample ejection. The titer plate-injector head may be utilized in various applications including capillary electrophoresis, chemical flow injection analysis, microsample array preparation, etc.

High spatial and temporal resolution cell manipulation techniques in microchannels.

PubMed

Novo, Pedro; Dell'Aica, Margherita; Janasek, Dirk; Zahedi, René P

2016-03-21

The advent of microfluidics has enabled thorough control of cell manipulation experiments in so called lab on chips. Lab on chips foster the integration of actuation and detection systems, and require minute sample and reagent amounts. Typically employed microfluidic structures have similar dimensions as cells, enabling precise spatial and temporal control of individual cells and their local environments. Several strategies for high spatio-temporal control of cells in microfluidics have been reported in recent years, namely methods relying on careful design of the microfluidic structures (e.g. pinched flow), by integration of actuators (e.g. electrodes or magnets for dielectro-, acousto- and magneto-phoresis), or integrations thereof. This review presents the recent developments of cell experiments in microfluidics divided into two parts: an introduction to spatial control of cells in microchannels followed by special emphasis in the high temporal control of cell-stimulus reaction and quenching. In the end, the present state of the art is discussed in line with future perspectives and challenges for translating these devices into routine applications.

Asymmetrical reverse vortex flow due to induced-charge electro-osmosis around carbon stacking structures.

PubMed

Sugioka, Hideyuki

2011-05-01

Broken symmetry of vortices due to induced-charge electro-osmosis (ICEO) around stacking structures is important for the generation of a large net flow in a microchannel. Following theoretical predictions in our previous study, we herein report experimental observations of asymmetrical reverse vortex flows around stacking structures of carbon posts with a large height (~110 μm) in water, prepared by the pyrolysis of a photoresist film in a reducing gas. Further, by the use of a coupled calculation method that considers boundary effects precisely, the experimental results, except for the problem of anomalous flow reversal, are successfully explained. That is, unlike previous predictions, the precise calculations here show that stacking structures accelerate a reverse flow rather than suppressing it for a microfluidic channel because of the deformation of electric fields near the stacking portions; these structures can also generate a large net flow theoretically in the direction opposite that of a previous prediction for a standard vortex flow. Furthermore, by solving the one-dimensional Poisson-Nernst-Plank (PNP) equations in the presence of ac electric fields, we find that the anomalous flow reversal occurs by the phase retardation between the induced diffuse charge and the tangential electric field. In addition, we successfully explain the nonlinearity of the flow velocity on the applied voltage by the PNP analysis. In the future, we expect to improve the pumping performance significantly by using stacking structures of conductive posts along with a low-cost process. © 2011 American Physical Society

Simultaneous determination of diclofenac potassium and methocarbamol in ternary mixture with guaifenesin by reversed phase liquid chromatography.

PubMed

Elkady, Ehab F

2010-09-15

New, simple, rapid and precise reversed phase liquid chromatographic (RP-LC) method has been developed for the simultaneous determination of diclofenac potassium (DP) and methocarbamol (MT) in ternary mixture with guaifenesin (GF), degradation product of methocarbamol. Chromatographic separation was achieved on a Symmetry Waters C18 column (150 mm x 4. 6mm, 5 microm). Gradient elution based on phosphate buffer pH (8)-acetonitrile at a flow rate of 1 mL min(-1) was applied. The UV detector was operated at 282 nm for DP and 274 nm for MT and GF. Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 0.05-16, 0.5-160 and 0.5-160 microg mL(-1) for DP, MT and GF, respectively. The optimized method proved to be specific, robust and accurate for the quality control of the cited drugs in pharmaceutical preparation. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Determination of three steroidal saponins from Ophiopogon japonicus (Liliaceae) via high-performance liquid chromatography with mass spectrometry.

PubMed

Wang, Yongyi; Xu, Jinzhong; Qu, Haibin

2013-01-01

A simple and accurate analytical method was developed for simultaneous quantification of three steroidal saponins in the roots of Ophiopogon japonicus via high-performance liquid chromatography (HPLC) with mass spectrometry (MS) in this study. Separation was performed on a Tigerkin C(18) column and detection was performed by mass spectrometry. A mobile phase consisted of 0.02% formic acid in water (v/v) and 0.02% formic acid in acetonitrile (v/v) was used with a flow rate of 0.5 mL min(-1). The quantitative HPLC-MS method was validated for linearity, precision, repeatability, stability, recovery, limits of detection and quantification. This developed method provides good linearity (r >0.9993), intra- and inter-day precisions (RSD <4.18%), repeatability (RSD <5.05%), stability (RSD <2.08%) and recovery (93.82-102.84%) for three steroidal saponins. It could be considered as a suitable quality control method for O. japonicus.

Adding-point strategy for reduced-order hypersonic aerothermodynamics modeling based on fuzzy clustering

NASA Astrophysics Data System (ADS)

Chen, Xin; Liu, Li; Zhou, Sida; Yue, Zhenjiang

2016-09-01

Reduced order models(ROMs) based on the snapshots on the CFD high-fidelity simulations have been paid great attention recently due to their capability of capturing the features of the complex geometries and flow configurations. To improve the efficiency and precision of the ROMs, it is indispensable to add extra sampling points to the initial snapshots, since the number of sampling points to achieve an adequately accurate ROM is generally unknown in prior, but a large number of initial sampling points reduces the parsimony of the ROMs. A fuzzy-clustering-based adding-point strategy is proposed and the fuzzy clustering acts an indicator of the region in which the precision of ROMs is relatively low. The proposed method is applied to construct the ROMs for the benchmark mathematical examples and a numerical example of hypersonic aerothermodynamics prediction for a typical control surface. The proposed method can achieve a 34.5% improvement on the efficiency than the estimated mean squared error prediction algorithm and shows same-level prediction accuracy.

VALVES FOR THE HIGH PRESSURE-HIGH TEMPERATURE (HP-HT) FLUORINATION SYSTEM. (Engineering Materials)

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

None

1963-10-31

This package contains two drawings of valves which eliminate errors in the gravimetric oxide dilution procedure of U/sup 235/ measurement. Isotopic contaminatioNonen in the high pressure fluorination reactor was corrected by changing the manner in which the Cu tubing joins the valve and by modification of the bellows. The compact inlet system was modified to improve the precision of the spectrometer analyses. Changes were raade in the basic leak and the air operator, which is a diaphragm-type valve, so that the setting of the flow level is controlled by the closure spring adjustment screw. This capillary-type leak has increased controlmore » range and sraooth control characteristics. It is simple to construct, is remotely operated and is free from corrosion failure. (F.S.)« less

Automatic Detection and Positioning of Ground Control Points Using TerraSAR-X Multiaspect Acquisitions

NASA Astrophysics Data System (ADS)

Montazeri, Sina; Gisinger, Christoph; Eineder, Michael; Zhu, Xiao xiang

2018-05-01

Geodetic stereo Synthetic Aperture Radar (SAR) is capable of absolute three-dimensional localization of natural Persistent Scatterer (PS)s which allows for Ground Control Point (GCP) generation using only SAR data. The prerequisite for the method to achieve high precision results is the correct detection of common scatterers in SAR images acquired from different viewing geometries. In this contribution, we describe three strategies for automatic detection of identical targets in SAR images of urban areas taken from different orbit tracks. Moreover, a complete work-flow for automatic generation of large number of GCPs using SAR data is presented and its applicability is shown by exploiting TerraSAR-X (TS-X) high resolution spotlight images over the city of Oulu, Finland and a test site in Berlin, Germany.

Use of instantaneous streamflow measurements to improve regression estimates of index flow for the summer month of lowest streamflow in Michigan

USGS Publications Warehouse

Holtschlag, David J.

2011-01-01

In Michigan, index flow Q50 is a streamflow characteristic defined as the minimum of median flows for July, August, and September. The state of Michigan uses index flow estimates to help regulate large (greater than 100,000 gallons per day) water withdrawals to prevent adverse effects on characteristic fish populations. At sites where long-term streamgages are located, index flows are computed directly from continuous streamflow records as GageQ50. In an earlier study, a multiple-regression equation was developed to estimate index flows IndxQ50 at ungaged sites. The index equation explains about 94 percent of the variability of index flows at 147 (index) streamgages by use of six explanatory variables describing soil type, aquifer transmissivity, land cover, and precipitation characteristics. This report extends the results of the previous study, by use of Monte Carlo simulations, to evaluate alternative flow estimators, DiscQ50, IntgQ50, SiteQ50, and AugmQ50. The Monte Carlo simulations treated each of the available index streamgages, in turn, as a miscellaneous site where streamflow conditions are described by one or more instantaneous measurements of flow. In the simulations, instantaneous flows were approximated by daily mean flows at the corresponding site. All estimators use information that can be obtained from instantaneous flow measurements and contemporaneous daily mean flow data from nearby long-term streamgages. The efficacy of these estimators was evaluated over a set of measurement intensities in which the number of simulated instantaneous flow measurements ranged from 1 to 100 at a site. The discrete measurement estimator DiscQ50 is based on a simple linear regression developed between information on daily mean flows at five or more streamgages near the miscellaneous site and their corresponding GageQ50 index flows. The regression relation then was used to compute a DiscQ50 estimate at the miscellaneous site by use of the simulated instantaneous flow measurement. This process was repeated to develop a set of DiscQ50 estimates for all simulated instantaneous measurements, a weighted DiscQ50 estimate was formed from this set. Results indicated that the expected value of this weighted estimate was more precise than the IndxQ50 estimate for all measurement intensities evaluated. The integrated index-flow estimator, IntgQ50, was formed by computing a weighted average of the index estimate IndxQ50 and the DiscQ50 estimate. Results indicated that the IntgQ50 estimator was more precise than the DiscQ50 estimator at low measurement intensities of one to two measurements. At greater measurement intensities, the precision of the IntgQ50 estimator converges to the DiscQ50 estimator. Neither the DiscQ50 nor the IntgQ50 estimators provided site-specific estimates. In particular, although expected values of DiscQ50 and IntgQ50 estimates converge with increasing measurement intensity, they do not necessarily converge to the site-specific value of Q50. The site estimator of flow, SiteQ50, was developed to facilitate this convergence at higher measurement intensities. This is accomplished by use of the median of simulated instantaneous flow values for each measurement intensity level. A weighted estimate of the median and information associated with the IntgQ50 estimate was used to form the SiteQ50 estimate. Initial simulations indicate that the SiteQ50 estimator generally has greater precision than the IntgQ50 estimator at measurement intensities greater than 3, however, additional analysis is needed to identify streamflow conditions under which instantaneous measurements will produce estimates that generally converge to the index flows. A preliminary augmented index regression equation was developed, which contains the index regression estimate and two additional variables associated with base-flow recession characteristics. When these recession variables were estimated as the medians of recession parameters compute

Optical flows method for lightweight agile remote sensor design and instrumentation

NASA Astrophysics Data System (ADS)

Wang, Chong; Xing, Fei; Wang, Hongjian; You, Zheng

2013-08-01

Lightweight agile remote sensors have become one type of the most important payloads and were widely utilized in space reconnaissance and resource survey. These imaging sensors are designed to obtain the high spatial, temporary and spectral resolution imageries. Key techniques in instrumentation include flexible maneuvering, advanced imaging control algorithms and integrative measuring techniques, which are closely correlative or even acting as the bottle-necks for each other. Therefore, mutual restrictive problems must be solved and optimized. Optical flow is the critical model which to be fully represented in the information transferring as well as radiation energy flowing in dynamic imaging. For agile sensors, especially with wide-field-of view, imaging optical flows may distort and deviate seriously when they perform large angle attitude maneuvering imaging. The phenomena are mainly attributed to the geometrical characteristics of the three-dimensional earth surface as well as the coupled effects due to the complicated relative motion between the sensor and scene. Under this circumstance, velocity fields distribute nonlinearly, the imageries may badly be smeared or probably the geometrical structures are changed since the image velocity matching errors are not having been eliminated perfectly. In this paper, precise imaging optical flow model is established for agile remote sensors, for which optical flows evolving is factorized by two forms, which respectively due to translational movement and image shape changing. Moreover, base on that, agile remote sensors instrumentation was investigated. The main techniques which concern optical flow modeling include integrative design with lightweight star sensors along with micro inertial measurement units and corresponding data fusion, the assemblies of focal plane layout and control, imageries post processing for agile remote sensors etc. Some experiments show that the optical analyzing method is effective to eliminate the limitations for the performance indexes, and succeeded to be applied for integrative system design. Finally, a principle prototype of agile remote sensor designed by the method is discussed.

Design, construction, and testing a purpose-built climate-controlled solvent vapor annealing chamber for guided self-assembly of block polymer thin films

NASA Astrophysics Data System (ADS)

Gnabasik, Ryan; Haase, Rustin; Baruth, Andrew

2014-03-01

Despite its efficacy to produce well-ordered, periodic nanostructures, the intricate role multiple parameters play in solvent vapor annealing has not been fully established. In solvent vapor annealing a thin polymer film is exposed to the vapors of a solvent(s) thus forming a swollen and mobile layer to direct the self-assembly process at the nanoscale. Recent developments in both theory and experiment have directly identified critical parameters, but controlling them in any systematic way has proven non-trivial. These identified parameters include vapor pressure, solvent concentration in the film, and, critically, the solvent evaporation rate. To explore their role, a purpose-built solvent vapor annealing chamber was designed and constructed. The all-metal chamber is inert to solvent exposure and pneumatically actuated valves allow for precision timing in the introduction and withdrawal of solvent vapor. Furthermore, the mass flow controlled inlet, chamber pressure gauges, in situ spectral reflectance-based thickness monitoring, and high precision micrometer relief valve, give real-time monitoring and control during the annealing and evaporation phases. Using atomic force microscopy to image the annealed films, we are able to map out the parameter space for a series of polystyrene- b-polylactide (Mn = 75 kg/mol and fPLA = 0.28) block polymer thin films with an intrinsic cylindrical morphology and identify their role in directed assembly. Funded by Creighton University Summer Research Grant.

Techniques used for the analysis of oculometer eye-scanning data obtained from an air traffic control display

NASA Technical Reports Server (NTRS)

Crawford, Daniel J.; Burdette, Daniel W.; Capron, William R.

1993-01-01

The methodology and techniques used to collect and analyze look-point position data from a real-time ATC display-format comparison experiment are documented. That study compared the delivery precision and controller workload of three final approach spacing aid display formats. Using an oculometer, controller lookpoint position data were collected, associated with gaze objects (e.g., moving aircraft) on the ATC display, and analyzed to determine eye-scan behavior. The equipment involved and algorithms for saving, synchronizing with the ATC simulation output, and filtering the data are described. Target (gaze object) and cross-check scanning identification algorithms are also presented. Data tables are provided of total dwell times, average dwell times, and cross-check scans. Flow charts, block diagrams, file record descriptors, and source code are included. The techniques and data presented are intended to benefit researchers in other studies that incorporate non-stationary gaze objects and oculometer equipment.

Engineering Heteromaterials to Control Lithium Ion Transport Pathways

DOE PAGES

Liu, Yang; Vishniakou, Siarhei; Yoo, Jinkyoung; ...

2015-12-21

Safe and efficient operation of lithium ion batteries requires precisely directed flow of lithium ions and electrons to control the first directional volume changes in anode and cathode materials. Understanding and controlling the lithium ion transport in battery electrodes becomes crucial to the design of high performance and durable batteries. Some recent work revealed that the chemical potential barriers encountered at the surfaces of heteromaterials play an important role in directing lithium ion transport at nanoscale. We utilize in situ transmission electron microscopy to demonstrate that we can switch lithiation pathways from radial to axial to grain-by-grain lithiation through themore » systematic creation of heteromaterial combinations in the Si-Ge nanowire system. Furthermore, our systematic studies show that engineered materials at nanoscale can overcome the intrinsic orientation-dependent lithiation, and open new pathways to aid in the development of compact, safe, and efficient batteries.« less

Compact and controlled microfluidic mixing and biological particle capture

NASA Astrophysics Data System (ADS)

Ballard, Matthew; Owen, Drew; Mills, Zachary Grant; Hesketh, Peter J.; Alexeev, Alexander

2016-11-01

We use three-dimensional simulations and experiments to develop a multifunctional microfluidic device that performs rapid and controllable microfluidic mixing and specific particle capture. Our device uses a compact microfluidic channel decorated with magnetic features. A rotating magnetic field precisely controls individual magnetic microbeads orbiting around the features, enabling effective continuous-flow mixing of fluid streams over a compact mixing region. We use computer simulations to elucidate the underlying physical mechanisms that lead to effective mixing and compare them with experimental mixing results. We study the effect of various system parameters on microfluidic mixing to design an efficient micromixer. We also experimentally and numerically demonstrate that orbiting microbeads can effectively capture particles transported by the fluid, which has major implications in pre-concentration and detection of biological particles including various cells and bacteria, with applications in areas such as point-of-care diagnostics, biohazard detection, and food safety. Support from NSF and USDA is gratefully acknowledged.

Photodrive of magnetic bubbles via magnetoelastic waves

PubMed Central

Ogawa, Naoki; Koshibae, Wataru; Beekman, Aron Jonathan; Nagaosa, Naoto; Kubota, Masashi; Kawasaki, Masashi; Tokura, Yoshinori

2015-01-01

Precise control of magnetic domain walls continues to be a central topic in the field of spintronics to boost infotech, logic, and memory applications. One way is to drive the domain wall by current in metals. In insulators, the incoherent flow of phonons and magnons induced by the temperature gradient can carry the spins, i.e., spin Seebeck effect, but the spatial and time dependence is difficult to control. Here, we report that coherent phonons hybridized with spin waves, magnetoelastic waves, can drive magnetic bubble domains, or curved domain walls, in an iron garnet, which are excited by ultrafast laser pulses at a nonabsorbing photon energy. These magnetoelastic waves were imaged by time-resolved Faraday microscopy, and the resultant spin transfer force was evaluated to be larger for domain walls with steeper curvature. This will pave a path for the rapid spatiotemporal control of magnetic textures in insulating magnets. PMID:26150487

Photodrive of magnetic bubbles via magnetoelastic waves.

PubMed

Ogawa, Naoki; Koshibae, Wataru; Beekman, Aron Jonathan; Nagaosa, Naoto; Kubota, Masashi; Kawasaki, Masashi; Tokura, Yoshinori

2015-07-21

Precise control of magnetic domain walls continues to be a central topic in the field of spintronics to boost infotech, logic, and memory applications. One way is to drive the domain wall by current in metals. In insulators, the incoherent flow of phonons and magnons induced by the temperature gradient can carry the spins, i.e., spin Seebeck effect, but the spatial and time dependence is difficult to control. Here, we report that coherent phonons hybridized with spin waves, magnetoelastic waves, can drive magnetic bubble domains, or curved domain walls, in an iron garnet, which are excited by ultrafast laser pulses at a nonabsorbing photon energy. These magnetoelastic waves were imaged by time-resolved Faraday microscopy, and the resultant spin transfer force was evaluated to be larger for domain walls with steeper curvature. This will pave a path for the rapid spatiotemporal control of magnetic textures in insulating magnets.

Engineering Heteromaterials to Control Lithium Ion Transport Pathways

PubMed Central

Liu, Yang; Vishniakou, Siarhei; Yoo, Jinkyoung; Dayeh, Shadi A.

2015-01-01

Safe and efficient operation of lithium ion batteries requires precisely directed flow of lithium ions and electrons to control the first directional volume changes in anode and cathode materials. Understanding and controlling the lithium ion transport in battery electrodes becomes crucial to the design of high performance and durable batteries. Recent work revealed that the chemical potential barriers encountered at the surfaces of heteromaterials play an important role in directing lithium ion transport at nanoscale. Here, we utilize in situ transmission electron microscopy to demonstrate that we can switch lithiation pathways from radial to axial to grain-by-grain lithiation through the systematic creation of heteromaterial combinations in the Si-Ge nanowire system. Our systematic studies show that engineered materials at nanoscale can overcome the intrinsic orientation-dependent lithiation, and open new pathways to aid in the development of compact, safe, and efficient batteries. PMID:26686655

Novel HPLC Analysis of Hydrocortisone in Conventional and Controlled-Release Pharmaceutical Preparations.

PubMed

Adi-Dako, Ofosua; Oppong Bekoe, Samuel; Ofori-Kwakye, Kwabena; Appiah, Enoch; Peprah, Paul

2017-01-01

An isocratic sensitive and precise reverse phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the determination and quantification of hydrocortisone in controlled-release and conventional (tablets and injections) pharmaceutical preparations. Chromatographic separation was achieved on an ODS (C18), 5  μ m, 4.6 × 150 mm, with an isocratic elution using a freshly prepared mobile phase of composition methanol : water : acetic acid (60 : 30 : 10, v/v/v) at a flow rate of 1.0 ml/min. The detection of the drug was successfully achieved at a wavelength of 254 nm. The retention time obtained for the drug was 2.26 min. The proposed method produced linear detectable responses in the concentration range of 0.02 to 0.4 mg/ml of hydrocortisone. High recoveries of 98-101% were attained at concentration levels of 80%, 100%, and 120%. The intraday and interday precision (RSD) were 0.19-0.55% and 0.33-0.71%, respectively. A comparison of hydrocortisone analyses data from the developed method and the official USP method showed no significant difference ( p > 0.05) at a 95% confidence interval. The method was successfully applied to the determination and quantification of hydrocortisone in six controlled-release and fifteen conventional release pharmaceutical preparations.

Novel HPLC Analysis of Hydrocortisone in Conventional and Controlled-Release Pharmaceutical Preparations

PubMed Central

Oppong Bekoe, Samuel; Appiah, Enoch; Peprah, Paul

2017-01-01

An isocratic sensitive and precise reverse phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the determination and quantification of hydrocortisone in controlled-release and conventional (tablets and injections) pharmaceutical preparations. Chromatographic separation was achieved on an ODS (C18), 5 μm, 4.6 × 150 mm, with an isocratic elution using a freshly prepared mobile phase of composition methanol : water : acetic acid (60 : 30 : 10, v/v/v) at a flow rate of 1.0 ml/min. The detection of the drug was successfully achieved at a wavelength of 254 nm. The retention time obtained for the drug was 2.26 min. The proposed method produced linear detectable responses in the concentration range of 0.02 to 0.4 mg/ml of hydrocortisone. High recoveries of 98–101% were attained at concentration levels of 80%, 100%, and 120%. The intraday and interday precision (RSD) were 0.19–0.55% and 0.33–0.71%, respectively. A comparison of hydrocortisone analyses data from the developed method and the official USP method showed no significant difference (p > 0.05) at a 95% confidence interval. The method was successfully applied to the determination and quantification of hydrocortisone in six controlled-release and fifteen conventional release pharmaceutical preparations. PMID:28660092

Evaluating the Impact of Global Warming on Water Balance of Maize by High-precision Controlled Experiment and MLCan model

NASA Astrophysics Data System (ADS)

Ma, Y.; Song, X.; Kumar, P.; Wu, Y.; Woo, D.; Le, P. V.; Ma, C.

2016-12-01

Increased temperature affects the agricultural hydrologic cycle not only by changing precipitation levels, evapotranspiration and the magnitude and timing of run-off, but also by impacting water flows and soil water dynamics. Accurate prediction of hydrologic change under global warming requires high-precision experiment and mathematical model to determine water interaction between interfaces in the soil-plant-atmosphere continuum. In this study, the weighting lysimeter and chamber were coupled to monitor water balance component dynamics of maize under controlled ambient temperature and elevated temperature of 2°C conditions. A mechanistic multilayer canopy-soil-root system model (MLCan) was used to predict hydrologic fluxes variation under different elevated temperature scenarios after calibration with experimental results. The results showed that maize growth period reduced 8 days under increased temperature of 2°C. The mean daily evapotranspiration, soil water storage change, and drainage was 2.66 mm, -2.75 mm, and 0.22 mm under controlled temperature condition, respectively. When temperature was elevated by 2°C, the average daily ET for maize significantly increased about 6.7% (p<0.05). However, there were non-significant impacts of increased temperature on the daily soil water storage change and drainage (p>0.05). Quantification of changes in water balance components induced by temperature increase for maize is critical for optimizing irrigation water management practices and improving water use efficiency.

NASA Tech Briefs, November 2005

NASA Technical Reports Server (NTRS)

2005-01-01

Topics covered include: Laser System for Precise, Unambiguous Range Measurements; Flexible Cryogenic Temperature and Liquid-Level Probes; Precision Cryogenic Dilatometer; Stroboscopic Interferometer for Measuring Mirror Vibrations; Some Improvements in H-PDLCs; Multiple-Bit Differential Detection of OQPSK; Absolute Position Encoders With Vertical Image Binning; Flexible, Carbon-Based Ohmic Contacts for Organic Transistors; GaAs QWIP Array Containing More Than a Million Pixels; AutoChem; Virtual Machine Language; Two-Dimensional Ffowcs Williams/Hawkings Equation Solver; Full Multigrid Flow Solver; Doclet To Synthesize UML; Computing Thermal Effects of Cavitation in Cryogenic Liquids; GUI for Computational Simulation of a Propellant Mixer; Control Program for an Optical-Calibration Robot; SQL-RAMS; Distributing Data from Desktop to Hand-Held Computers; Best-Fit Conic Approximation of Spacecraft Trajectory; Improved Charge-Transfer Fluorescent Dyes; Stability-Augmentation Devices for Miniature Aircraft; Tool Measures Depths of Defects on a Case Tang Joint; Two Heat-Transfer Improvements for Gas Liquefiers; Controlling Force and Depth in Friction Stir Welding; Spill-Resistant Alkali-Metal-Vapor Dispenser; A Methodology for Quantifying Certain Design Requirements During the Design Phase; Measuring Two Key Parameters of H3 Color Centers in Diamond; Improved Compression of Wavelet-Transformed Images; NASA Interactive Forms Type Interface - NIFTI; Predicting Numbers of Problems in Development of Software; Hot-Electron Photon Counters for Detecting Terahertz Photons; Magnetic Variations Associated With Solar Flares; and Artificial Intelligence for Controlling Robotic Aircraft.

A sliding plate microgap rheometer for the simultaneous measurement of shear stress and first normal stress difference

NASA Astrophysics Data System (ADS)

Baik, Seung Jae; Moldenaers, Paula; Clasen, Christian

2011-03-01

A new generation of the "flexure-based microgap rheometer" (the N-FMR) has been developed which is also capable of measuring, in addition to the shear stress, the first normal stress difference of micrometer thin fluid films. This microgap rheometer with a translation system based on compound spring flexures measures the rheological properties of microliter samples of complex fluids confined in a plane couette configuration with gap distances of h = 1-400 μm up to shear rates of dot γ = 3000 s-1. Feed back loop controlled precise positioning of the shearing surfaces with response times <1 ms enables to control the parallelism within 1.5 μrad and to maintain the gap distance within 20 nm. This precise gap control minimizes squeeze flow effects and allows therefore to measure the first normal stress difference N1 of the thin film down to a micrometer gap distance, with a lower limit of {{N_1 }/{dot γ }} = 9.375 × 10^{ - 11} {η/{h^2 }} that depends on the shear viscosity η and the squared inverse gap. Structural development of complex fluids in the confinement can be visualized by using a beam splitter on the shearing surface and a long working distance microscope. In summary, this new instrument allows to investigate the confinement dependent rheological and morphological evolution of micrometer thin films.

Sheathless Size-Based Acoustic Particle Separation

PubMed Central

Guldiken, Rasim; Jo, Myeong Chan; Gallant, Nathan D.; Demirci, Utkan; Zhe, Jiang

2012-01-01

Particle separation is of great interest in many biological and biomedical applications. Flow-based methods have been used to sort particles and cells. However, the main challenge with flow based particle separation systems is the need for a sheath flow for successful operation. Existence of the sheath liquid dilutes the analyte, necessitates precise flow control between sample and sheath flow, requires a complicated design to create sheath flow and separation efficiency depends on the sheath liquid composition. In this paper, we present a microfluidic platform for sheathless particle separation using standing surface acoustic waves. In this platform, particles are first lined up at the center of the channel without introducing any external sheath flow. The particles are then entered into the second stage where particles are driven towards the off-center pressure nodes for size based separation. The larger particles are exposed to more lateral displacement in the channel due to the acoustic force differences. Consequently, different-size particles are separated into multiple collection outlets. The prominent feature of the present microfluidic platform is that the device does not require the use of the sheath flow for positioning and aligning of particles. Instead, the sheathless flow focusing and separation are integrated within a single microfluidic device and accomplished simultaneously. In this paper, we demonstrated two different particle size-resolution separations; (1) 3 μm and 10 μm and (2) 3 μm and 5 μm. Also, the effects of the input power, the flow rate, and particle concentration on the separation efficiency were investigated. These technologies have potential to impact broadly various areas including the essential microfluidic components for lab-on-a-chip system and integrated biological and biomedical applications. PMID:22368502

Study of nanometer-level precise phase-shift system used in electronic speckle shearography and phase-shift pattern interferometry

NASA Astrophysics Data System (ADS)

Jing, Chao; Liu, Zhongling; Zhou, Ge; Zhang, Yimo

2011-11-01

The nanometer-level precise phase-shift system is designed to realize the phase-shift interferometry in electronic speckle shearography pattern interferometry. The PZT is used as driving component of phase-shift system and translation component of flexure hinge is developed to realize micro displacement of non-friction and non-clearance. Closed-loop control system is designed for high-precision micro displacement, in which embedded digital control system is developed for completing control algorithm and capacitive sensor is used as feedback part for measuring micro displacement in real time. Dynamic model and control model of the nanometer-level precise phase-shift system is analyzed, and high-precision micro displacement is realized with digital PID control algorithm on this basis. It is proved with experiments that the location precision of the precise phase-shift system to step signal of displacement is less than 2nm and the location precision to continuous signal of displacement is less than 5nm, which is satisfied with the request of the electronic speckle shearography and phase-shift pattern interferometry. The stripe images of four-step phase-shift interferometry and the final phase distributed image correlated with distortion of objects are listed in this paper to prove the validity of nanometer-level precise phase-shift system.

Tunable osteogenic differentiation of hMPCs in tubular perfusion system bioreactor.

PubMed

Nguyen, Bao-Ngoc B; Ko, Henry; Fisher, John P

2016-08-01

The use of bioreactors for bone tissue engineering has been widely investigated. While the benefits of shear stress on osteogenic differentiation are well known, the underlying effects of dynamic culture on subpopulations within a bioreactor are less evident. In this work, we explore the influence of applied flow in the tubular perfusion system (TPS) bioreactor on the osteogenic differentiation of human mesenchymal progenitor cells (hMPCs), specifically analyzing the effects of axial position along the growth chamber. TPS bioreactor experiments conducted with unidirectional flow demonstrated enhanced expression of osteogenic markers in cells cultured downstream from the inlet flow. We utilized computational fluid dynamic modeling to confirm uniform shear stress distribution on the surface of the scaffolds and along the length of the growth chamber. The concept of paracrine signaling between cell populations was validated with the use of alternating flow, which diminished the differences in osteogenic differentiation between cells cultured at the inlet and outlet of the growth chamber. After the addition of controlled release of bone morphogenic protein-2 (BMP-2) into the system, osteogenic differentiation among subpopulations along the growth chamber was augmented, yet remained homogenous. These results allow for greater understanding of axial bioreactor cultures, their microenvironment, and how well-established parameters of osteogenic differentiation affect bone tissue development. With this work, we have demonstrated the capability of tuning osteogenic differentiation of hMPCs through the application of fluid flow and the addition of exogenous growth factors. Such precise control allows for the culture of distinct subpopulation within one dynamic system for the use of complex engineered tissue constructs. Biotechnol. Bioeng. 2016;113: 1805-1813. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Gauge-invariant flow equation

NASA Astrophysics Data System (ADS)

Wetterich, C.

2018-06-01

We propose a closed gauge-invariant functional flow equation for Yang-Mills theories and quantum gravity that only involves one macroscopic gauge field or metric. It is based on a projection on physical and gauge fluctuations. Deriving this equation from a functional integral we employ the freedom in the precise choice of the macroscopic field and the effective average action in order to realize a closed and simple form of the flow equation.

Micromixer-based time-resolved NMR: applications to ubiquitin protein conformation.

PubMed

Kakuta, Masaya; Jayawickrama, Dimuthu A; Wolters, Andrew M; Manz, Andreas; Sweedler, Jonathan V

2003-02-15

Time-resolved NMR spectroscopy is used to studychanges in protein conformation based on the elapsed time after a change in the solvent composition of a protein solution. The use of a micromixer and a continuous-flow method is described where the contents of two capillary flows are mixed rapidly, and then the NMR spectra of the combined flow are recorded at precise time points. The distance after mixing the two fluids and flow rates define the solvent-protein interaction time; this method allows the measurement of NMR spectra at precise mixing time points independent of spectral acquisition time. Integration of a micromixer and a microcoil NMR probe enables low-microliter volumes to be used without losing significant sensitivity in the NMR measurement. Ubiquitin, the model compound, changes its conformation from native to A-state at low pH and in 40% or higher methanol/water solvents. Proton NMR resonances of the His-68 and the Tyr-59 of ubiquitin are used to probe the conformational changes. Mixing ubiquitin and methanol solutions under low pH at microliter per minute flow rates yields both native and A-states. As the flow rate decreases, yielding longer reaction times, the population of the A-state increases. The micromixer-NMR system can probe reaction kinetics on a time scale of seconds.

Precision control of multiple quantum cascade lasers for calibration systems

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

Taubman, Matthew S., E-mail: Matthew.Taubman@pnnl.gov; Myers, Tanya L.; Pratt, Richard M.

We present a precision, 1-A, digitally interfaced current controller for quantum cascade lasers, with demonstrated temperature coefficients for continuous and 40-kHz full-depth square-wave modulated operation, of 1–2 ppm/ °C and 15 ppm/ °C, respectively. High precision digital to analog converters (DACs) together with an ultra-precision voltage reference produce highly stable, precision voltages, which are selected by a multiplexer (MUX) chip to set output currents via a linear current regulator. The controller is operated in conjunction with a power multiplexing unit, allowing one of three lasers to be driven by the controller, while ensuring protection of controller and all lasers during operation, standby,more » and switching. Simple ASCII commands sent over a USB connection to a microprocessor located in the current controller operate both the controller (via the DACs and MUX chip) and the power multiplexer.« less

High Precision 40Ar/39Ar Geochronology of Servilleta Basalts of the Rio Grande Gorge, New Mexico

NASA Astrophysics Data System (ADS)

Cosca, M. A.; Thompson, R. A.; Turner, K. J.

2014-12-01

New geologic mapping and high-precision 40Ar/39Ar geochronology within the Taos Plateau in northern New Mexico indicate a period of vigorous volcanic activity between ~5.5 and ~1 Ma. Over 50 visible volcanic centers formed during this time together with an unresolved number of vents, fissures, and volcanic centers buried by intercalated volcanic rock and sedimentary basin fill. Defining the volcanic stratigraphy is essential for models of regional groundwater flow and for understanding the geologic evolution of the Pliocene to Recent Rio Grande rift. A spectacular stratigraphic section of volcanic rock related to Rio Grande rifting is visible from the High Bridge, just a few miles outside of Taos, NM, where a 240 m canyon is incised through the basal, middle, and upper Servilleta basalt flow packages (Dungan et al., 1984). Fresh basalt from a vertical transect of the canyon near the High Bridge were analyzed by 40Ar/39Ar methods on ~3 mm3 rock fragments using an ARGUS VI mass spectrometer and the resulting 40Ar/39Ar ages define a precise emplacement chronology of the entire stratigraphic section. The basal flow package records ages of 4.78 ± 0.03 Ma (relative to FCT sanidine = 28.204 Ma; all errors 2 sigma) at river level, 4.77 ± 0.03 Ma at mid flow, and 4.50 ± 0.04 Ma at the top of the flow. The middle flow package records ages of 4.11 ± 0.03 Ma at the base of the flow, 4.08 ± 0.04 Ma mid flow, and 4.02 ± 0.06 Ma at the top of the flow. The upper basalt package records ages of 3.69 ± 0.06 Ma at the base of the flow and 3.59 ± 0.08 Ma at the top of the flow. These data support rapid effusion of voluminous lava flows on time scales of 100-200 ka. Two reddish paleosols separating the Servilleta packages each developed during a 400 ka period of volcanic quiescence. First order calculations using exposed lava thicknesses in the gorge and areal exposures suggest each flow package represents emplacement of ~200 km3 of basalt. Because no exposed vent of appropriate age has been identified that could produce such basalt volumes, the Servilleta basalts probably erputed from buried vents and/or fissures, possibly oriented along the northwest trending fault systems defining the Rio Grande rift graben.

Software for real-time control of a tidal liquid ventilator.

PubMed

Heckman, J L; Hoffman, J; Shaffer, T H; Wolfson, M R

1999-01-01

The purpose of this project was to develop and test computer software and control algorithms designed to operate a tidal liquid ventilator. The tests were executed on a 90-MHz Pentium PC with 16 MB RAM and a prototype liquid ventilator. The software was designed using Microsoft Visual C++ (Ver. 5.0) and the Microsoft Foundation Classes. It uses a graphic user interface, is multithreaded, runs in real time, and has a built-in simulator that facilitates user education in liquid-ventilation principles. The operator can use the software to specify ventilation parameters such as the frequency of ventilation, the tidal volume, and the inspiratory-expiratory time ratio. Commands are implemented via control of the pump speed and by setting the position of two two-way solenoid-controlled valves. Data for use in monitoring and control are gathered by analog-to-digital conversion. Control strategies are implemented to maintain lung volumes and airway pressures within desired ranges, according to limits set by the operator. Also, the software allows the operator to define the shape of the flow pulse during inspiration and expiration, and to optimize perfluorochemical liquid transfer while minimizing airway pressures and maintaining the desired tidal volume. The operator can stop flow during inspiration and expiration to measure alveolar pressures. At the end of expiration, the software stores all user commands and 30 ventilation parameters into an Excel spreadsheet for later review and analysis. Use of these software and control algorithms affords user-friendly operation of a tidal liquid ventilator while providing precise control of ventilation parameters.

Automated analysis of flow cytometric data for measuring neutrophil CD64 expression using a multi-instrument compatible probability state model.

PubMed

Wong, Linda; Hill, Beth L; Hunsberger, Benjamin C; Bagwell, C Bruce; Curtis, Adam D; Davis, Bruce H

2015-01-01

Leuko64™ (Trillium Diagnostics) is a flow cytometric assay that measures neutrophil CD64 expression and serves as an in vitro indicator of infection/sepsis or the presence of a systemic acute inflammatory response. Leuko64 assay currently utilizes QuantiCALC, a semiautomated software that employs cluster algorithms to define cell populations. The software reduces subjective gating decisions, resulting in interanalyst variability of <5%. We evaluated a completely automated approach to measuring neutrophil CD64 expression using GemStone™ (Verity Software House) and probability state modeling (PSM). Four hundred and fifty-seven human blood samples were processed using the Leuko64 assay. Samples were analyzed on four different flow cytometer models: BD FACSCanto II, BD FACScan, BC Gallios/Navios, and BC FC500. A probability state model was designed to identify calibration beads and three leukocyte subpopulations based on differences in intensity levels of several parameters. PSM automatically calculates CD64 index values for each cell population using equations programmed into the model. GemStone software uses PSM that requires no operator intervention, thus totally automating data analysis and internal quality control flagging. Expert analysis with the predicate method (QuantiCALC) was performed. Interanalyst precision was evaluated for both methods of data analysis. PSM with GemStone correlates well with the expert manual analysis, r(2) = 0.99675 for the neutrophil CD64 index values with no intermethod bias detected. The average interanalyst imprecision for the QuantiCALC method was 1.06% (range 0.00-7.94%), which was reduced to 0.00% with the GemStone PSM. The operator-to-operator agreement in GemStone was a perfect correlation, r(2) = 1.000. Automated quantification of CD64 index values produced results that strongly correlate with expert analysis using a standard gate-based data analysis method. PSM successfully evaluated flow cytometric data generated by multiple instruments across multiple lots of the Leuko64 kit in all 457 cases. The probability-based method provides greater objectivity, higher data analysis speed, and allows for greater precision for in vitro diagnostic flow cytometric assays. © 2015 International Clinical Cytometry Society.

Proliferation of Precision Strike: Issues for Congress

DTIC Science & Technology

2012-05-14

industrial base. Finally, should Congress legislate requirements for DOD to develop precision strike countermeasures and then provide funding for that...Defense, Part 187 – Environmental Effects Abroad of Major Department of Defense Actions, Section 187.3: Definitions. 32 Bryan Clark and Dan Whiteneck...so many missiles ... referring to reports of Venezuelan arms flowing to Colombian guerrillas.... The Chavez regime also has close ties with

Numerical Study Comparing RANS and LES Approaches on a Circulation Control Airfoil

NASA Technical Reports Server (NTRS)

Rumsey, Christopher L.; Nishino, Takafumi

2011-01-01

A numerical study over a nominally two-dimensional circulation control airfoil is performed using a large-eddy simulation code and two Reynolds-averaged Navier-Stokes codes. Different Coanda jet blowing conditions are investigated. In addition to investigating the influence of grid density, a comparison is made between incompressible and compressible flow solvers. The incompressible equations are found to yield negligible differences from the compressible equations up to at least a jet exit Mach number of 0.64. The effects of different turbulence models are also studied. Models that do not account for streamline curvature effects tend to predict jet separation from the Coanda surface too late, and can produce non-physical solutions at high blowing rates. Three different turbulence models that account for streamline curvature are compared with each other and with large eddy simulation solutions. All three models are found to predict the Coanda jet separation location reasonably well, but one of the models predicts specific flow field details near the Coanda surface prior to separation much better than the other two. All Reynolds-averaged Navier-Stokes computations produce higher circulation than large eddy simulation computations, with different stagnation point location and greater flow acceleration around the nose onto the upper surface. The precise reasons for the higher circulation are not clear, although it is not solely a function of predicting the jet separation location correctly.

Generation of Monodisperse Liquid Droplets in a Microfluidic Chip Using a High-Speed Gaseous Microflow

NASA Astrophysics Data System (ADS)

Tirandazi, Pooyan; Hidrovo, Carlos

2015-11-01

Over the last few years, microfluidic systems known as Lab-on-a-Chip (LOC) and micro total analysis systems (μTAS) have been increasingly developed as essential components for numerous biochemical applications. Droplet microfluidics, however, provides a distinctive attribute for delivering and processing discrete as well as ultrasmall volumes of fluid, which make droplet-based systems more beneficial over their continuous-phase counterparts. Droplet generation in its conventional scheme usually incorporates the injection of a liquid (water) into a continuous immiscible liquid (oil) medium. In this study we demonstrate a novel scheme for controlled generation of monodisperse droplets in confined gas-liquid microflows. We experimentally investigate the manipulation of water droplets in flow-focusing configurations using a high inertial air stream. Different flow regimes are observed by varying the gas and liquid flow rates, among which, the ``dripping regime'' where monodisperse droplets are generated is of great importance. The controlled size and generation rate of droplets in this region provide the capability for precise and contaminant-free delivery of microliter to nanoliter volumes of fluid. Furthermore, the high speed droplets generated in this method represent the basis for a new approach based on droplet pair collisions for fast efficient micromixing which provides a significant development in modern LOC and μTAS devices. This project is currently being supported by an NSF CAREER Award grant CBET-1151091.

Additively manufactured MEMS multiplexed coaxial electrospray sources for high-throughput, uniform generation of core-shell microparticles.

PubMed

Olvera-Trejo, D; Velásquez-García, L F

2016-10-18

This study reports the first MEMS multiplexed coaxial electrospray sources in the literature. Coaxial electrospraying is a microencapsulation technology based on electrohydrodynamic jetting of two immiscible liquids, which allows precise control with low size variation of the geometry of the core-shell particles it generates, which is of great importance in numerous biomedical and engineering applications, e.g., drug delivery and self-healing composites. By implementing monolithic planar arrays of miniaturized coaxial electrospray emitters that work uniformly in parallel, the throughput of the compound microdroplet source is greatly increased, making the microencapsulation technology compatible with low-cost commercial applications. Miniaturized core-shell particle generators with up to 25 coaxial electrospray emitters (25 emitters cm -2 ) were fabricated via stereolithography, which is an additive manufacturing process that can create complex microfluidic devices at a small fraction of the cost per device and fabrication time associated with silicon-based counterparts. The characterization of devices with the same emitter structure but different array sizes demonstrates uniform array operation. Moreover, the data demonstrate that the per-emitter current is approximately proportional to the square root of the flow rate of the driving liquid, and it is independent of the flow rate of the driven liquid, as predicted by the theory. The core/shell diameters and the size distribution of the generated compound microparticles can be modulated by controlling the flow rates fed to the emitters.

SPARK GAP SWITCH

DOEpatents

Neal, R.B.

1957-12-17

An improved triggered spark gap switch is described, capable of precisely controllable firing time while switching very large amounts of power. The invention in general comprises three electrodes adjustably spaced and adapted to have a large potential impressed between the outer electrodes. The central electrode includes two separate elements electrically connected togetaer and spaced apart to define a pair of spark gaps between the end electrodes. Means are provided to cause the gas flow in the switch to pass towards the central electrode, through a passage in each separate element, and out an exit disposed between the two separate central electrode elements in order to withdraw ions from the spark gap.

Autonomous unmanned air vehicles (UAV) techniques

NASA Astrophysics Data System (ADS)

Hsu, Ming-Kai; Lee, Ting N.

2007-04-01

The UAVs (Unmanned Air Vehicles) have great potentials in different civilian applications, such as oil pipeline surveillance, precision farming, forest fire fighting (yearly), search and rescue, boarder patrol, etc. The related industries of UAVs can create billions of dollars for each year. However, the road block of adopting UAVs is that it is against FAA (Federal Aviation Administration) and ATC (Air Traffic Control) regulations. In this paper, we have reviewed the latest technologies and researches on UAV navigation and obstacle avoidance. We have purposed a system design of Jittering Mosaic Image Processing (JMIP) with stereo vision and optical flow to fulfill the functionalities of autonomous UAVs.

Routine Clinical Quantitative Rest Stress Myocardial Perfusion for Managing Coronary Artery Disease: Clinical Relevance of Test-Retest Variability.

PubMed

Kitkungvan, Danai; Johnson, Nils P; Roby, Amanda E; Patel, Monika B; Kirkeeide, Richard; Gould, K Lance

2017-05-01

Positron emission tomography (PET) quantifies stress myocardial perfusion (in cc/min/g) and coronary flow reserve to guide noninvasively the management of coronary artery disease. This study determined their test-retest precision within minutes and daily biological variability essential for bounding clinical decision-making or risk stratification based on low flow ischemic thresholds or follow-up changes. Randomized trials of fractional flow reserve-guided percutaneous coronary interventions established an objective, quantitative, outcomes-driven standard of physiological stenosis severity. However, pressure-derived fractional flow reserve requires invasive coronary angiogram and was originally validated by comparison to noninvasive PET. The time course and test-retest precision of serial quantitative rest-rest and stress-stress global myocardial perfusion by PET within minutes and days apart in the same patient were compared in 120 volunteers undergoing serial 708 quantitative PET perfusion scans using rubidium 82 (Rb-82) and dipyridamole stress with a 2-dimensional PET-computed tomography scanner (GE DST 16) and University of Texas HeartSee software with our validated perfusion model. Test-retest methodological precision (coefficient of variance) for serial quantitative global myocardial perfusion minutes apart is ±10% (mean ΔSD at rest ±0.09, at stress ±0.23 cc/min/g) and for days apart is ±21% (mean ΔSD at rest ±0.2, at stress ±0.46 cc/min/g) reflecting added biological variability. Global myocardial perfusion at 8 min after 4-min dipyridamole infusion is 10% higher than at standard 4 min after dipyridamole. Test-retest methodological precision of global PET myocardial perfusion by serial rest or stress PET minutes apart is ±10%. Day-to-different-day biological plus methodological variability is ±21%, thereby establishing boundaries of variability on physiological severity to guide or follow coronary artery disease management. Maximum stress increases perfusion and coronary flow reserve, thereby reducing potentially falsely low values mimicking ischemia. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Bubble Generation in a Continuous Liquid Flow Under Reduced Gravity Conditions

NASA Technical Reports Server (NTRS)

Pais, Salvatore Cezar

1999-01-01

The present work reports a study of bubble generation under reduced gravity conditions for both co-flow and cross-flow configurations. Experiments were performed aboard the DC-9 Reduced Gravity Aircraft at NASA Glenn Research Center, using an air-water system. Three different flow tube diameters were used: 1.27, 1.9, and 2.54 cm. Two different ratios of air injection nozzle to tube diameters were considered: 0.1 and 0.2. Gas and liquid volumetric flow rates were varied from 10 to 200 ml/s. It was experimentally observed that with increasing superficial liquid velocity, the bubbles generated decreased in size. The bubble diameter was shown to increase with increasing air injection nozzle diameters. As the tube diameter was increased, the size of the detached bubbles increased. Likewise, as the superficial liquid velocity was increased, the frequency of bubble formation increased and thus the time to detach forming bubbles decreased. Independent of the flow configuration (for either single nozzle or multiple nozzle gas injection), void fraction and hence flow regime transition can be controlled in a somewhat precise manner by solely varying the gas and liquid volumetric flow rates. On the other hand, it is observed that uniformity of bubble size can be controlled more accurately by using single nozzle gas injection than by using multiple port injection, since this latter system gives rise to unpredictable coalescence of adjacent bubbles. A theoretical model, based on an overall force balance, is employed to study single bubble generation in the dynamic and bubbly flow regime. Under conditions of reduced gravity, the gas momentum flux enhances bubble detachment; however, the surface tension forces at the nozzle tip inhibits bubble detachment. Liquid drag and inertia can act either as attaching or detaching force, depending on the relative velocity of the bubble with respect to the surrounding liquid. Predictions of the theoretical model compare well with performed experiments. However, at higher superficial,liquid velocities, the bubble neck length begins to significantly deviate from the value of the air injection nozzle diameter and thus the theory no longer predicts the experiment behavior. Effects of fluid properties, injection geometry and flow conditions on generated bubble size are investigated using the theoretical model. It is shown that bubble diameter is larger in a reduced gravity environment than in a normal gravity environment at similar flow condition and flow geometry.

A novel microfluidic system for the mass production of Inertial Fusion Energy shells

NASA Astrophysics Data System (ADS)

Inoue, N. T.

2016-04-01

A system which can mass produce millimetre sized spherical polymer shells economically and with high precision will be a great step towards the Inertial Fusion Energy goal. Microfluidics has shown itself to be a disruptive technology, where a rapid and continuous production of compound emulsions can be processed into such shells. Planar emulsion generators co-flow-focus in one step (COFON) and cascaded co-flow- focus (COFUS) enable millimetre compound emulsions to be produced using a one or two step formation process respectively. The co-flow-focus geometry uses symmetric and curved carrier fluid entrance walls to create a focusing orifice-minima and a carrier flow which aids movement and shaping of the dispersed fluid(s) towards the outlet, whilst maintaining operation in the dripping regime. Precision concentric alignment of these compound emulsions remains one of the greatest challenges. However steps to solve this passively using curved channel modulation to perturbate the emulsion have shown that rapid alignment can be achieved. Issues with satellite droplet formation, repeatability of the emulsion generation and cost are also addressed.

One-dimensional acoustic standing waves in rectangular channels for flow cytometry.

PubMed

Austin Suthanthiraraj, Pearlson P; Piyasena, Menake E; Woods, Travis A; Naivar, Mark A; Lόpez, Gabriel P; Graves, Steven W

2012-07-01

Flow cytometry has become a powerful analytical tool for applications ranging from blood diagnostics to high throughput screening of molecular assemblies on microsphere arrays. However, instrument size, expense, throughput, and consumable use limit its use in resource poor areas of the world, as a component in environmental monitoring, and for detection of very rare cell populations. For these reasons, new technologies to improve the size and cost-to-performance ratio of flow cytometry are required. One such technology is the use of acoustic standing waves that efficiently concentrate cells and particles to the center of flow channels for analysis. The simplest form of this method uses one-dimensional acoustic standing waves to focus particles in rectangular channels. We have developed one-dimensional acoustic focusing flow channels that can be fabricated in simple capillary devices or easily microfabricated using photolithography and deep reactive ion etching. Image and video analysis demonstrates that these channels precisely focus single flowing streams of particles and cells for traditional flow cytometry analysis. Additionally, use of standing waves with increasing harmonics and in parallel microfabricated channels is shown to effectively create many parallel focused streams. Furthermore, we present the fabrication of an inexpensive optical platform for flow cytometry in rectangular channels and use of the system to provide precise analysis. The simplicity and low-cost of the acoustic focusing devices developed here promise to be effective for flow cytometers that have reduced size, cost, and consumable use. Finally, the straightforward path to parallel flow streams using one-dimensional multinode acoustic focusing, indicates that simple acoustic focusing in rectangular channels may also have a prominent role in high-throughput flow cytometry. Copyright © 2012 Elsevier Inc. All rights reserved.

FLEET Velocimetry Measurements on a Transonic Airfoil

NASA Technical Reports Server (NTRS)

Burns, Ross A.; Danehy, Paul M.

2017-01-01

Femtosecond laser electronic excitation tagging (FLEET) velocimetry was used to study the flowfield around a symmetric, transonic airfoil in the NASA Langley 0.3-m TCT facility. A nominal Mach number of 0.85 was investigated with a total pressure of 125 kPa and total temperature of 280 K. Two-components of velocity were measured along vertical profiles at different locations above, below, and aft of the airfoil at angles of attack of 0 deg, 3.5 deg, and 7deg. Measurements were assessed for their accuracy, precision, dynamic range, spatial resolution, and overall measurement uncertainty in the context of the applied flowfield. Measurement precisions as low as 1 m/s were observed, while overall uncertainties ranged from 4 to 5 percent. Velocity profiles within the wake showed sufficient accuracy, precision, and sensitivity to resolve both the mean and fluctuating velocities and general flow physics such as shear layer growth. Evidence of flow separation is found at high angles of attack.

Estimation of suspended-sediment rating curves and mean suspended-sediment loads

USGS Publications Warehouse

Crawford, Charles G.

1991-01-01

A simulation study was done to evaluate: (1) the accuracy and precision of parameter estimates for the bias-corrected, transformed-linear and non-linear models obtained by the method of least squares; (2) the accuracy of mean suspended-sediment loads calculated by the flow-duration, rating-curve method using model parameters obtained by the alternative methods. Parameter estimates obtained by least squares for the bias-corrected, transformed-linear model were considerably more precise than those obtained for the non-linear or weighted non-linear model. The accuracy of parameter estimates obtained for the biascorrected, transformed-linear and weighted non-linear model was similar and was much greater than the accuracy obtained by non-linear least squares. The improved parameter estimates obtained by the biascorrected, transformed-linear or weighted non-linear model yield estimates of mean suspended-sediment load calculated by the flow-duration, rating-curve method that are more accurate and precise than those obtained for the non-linear model.

Repeatability and oblique flow response characteristics of current meters

USGS Publications Warehouse

Fulford, Janice M.; Thibodeaux, Kirk G.; Kaehrle, William R.; ,

1993-01-01

Laboratory investigation into the precision and accuracy of various mechanical-current meters are presented. Horizontal-axis and vertical-axis meters that are used for the measurement of point velocities in streams and rivers were tested. Meters were tested for repeatability and response to oblique flows. Both horizontal- and vertical-axis meters were found to under- and over-register oblique flows with errors generally increasing as the velocity and angle of flow increased. For the oblique flow tests, magnitude of errors were smallest for horizontal-axis meters. Repeatability of all meters tested was good, with the horizontal- and vertical-axis meters performing similarly.

The very local Hubble flow: Computer simulations of dynamical history

NASA Astrophysics Data System (ADS)

Chernin, A. D.; Karachentsev, I. D.; Valtonen, M. J.; Dolgachev, V. P.; Domozhilova, L. M.; Makarov, D. I.

2004-02-01

The phenomenon of the very local (≤3 Mpc) Hubble flow is studied on the basis of the data of recent precision observations. A set of computer simulations is performed to trace the trajectories of the flow galaxies back in time to the epoch of the formation of the Local Group. It is found that the ``initial conditions'' of the flow are drastically different from the linear velocity-distance relation. The simulations enable one also to recognize the major trends of the flow evolution and identify the dynamical role of universal antigravity produced by the cosmic vacuum.

Visualization of a Capsule Entry Vehicle Reaction-Control System (RCS) Thruster

NASA Technical Reports Server (NTRS)

Danehy, P. M.; Wilkes, J. A.; Brauckmann, G. J.; Alderfer, D. W.; Jones, S. B.; Patry, D. P.

2006-01-01

Planar laser-induced fluorescence (PLIF) was used to visualize the reaction control system (RCS) jet flow emanating from the aft-body of an Apollo-geometry capsule test article in the NASA Langley Research Center 31-Inch Mach 10 Air wind tunnel. The RCS jet was oriented normal to the aft surface of the model and had a nominal Mach number of 2.94. The composition of the jet gas by mass was 95% nitrogen (N2) and 5% nitric oxide (NO). The RCS jet flowrate varied between zero and 0.5 standard liters per minute and the angle of attack and tunnel stagnation pressure were also varied. PLIF was used to excite the NO molecules for flow visualization. These flow visualization images were processed to determine the trajectory and to quantify the flapping of the RCS jet. The spatial resolution of the jet trajectory measurement was about 1 mm and the single-shot precision of the measurement was estimated to be 0.02 mm in the far field of the jet plume. The jet flapping, measured by the standard deviation of the jet centerline position was as large as 0.9 mm, while the jet was 1.5-4 mm in diameter (full width at half maximum). Schlieren flow visualization images were obtained for comparison with the PLIF. Surface pressures were also measured and presented. Virtual Diagnostics Interface (VIDI) technology developed at NASA Langley was used to superimpose and visualize the data sets. The measurements demonstrate some of the capabilities of the PLIF method while providing a test case for computational fluid dynamics (CFD) validation.

Development and Operation of an Automatic Rotor Trim Control System for the UH-60 Individual Blade Control Wind Tunnel Test

NASA Technical Reports Server (NTRS)

Theodore, Colin R.; Tischler, Mark B.

2010-01-01

An automatic rotor trim control system was developed and successfully used during a wind tunnel test of a full-scale UH-60 rotor system with Individual Blade Control (IBC) actuators. The trim control system allowed rotor trim to be set more quickly, precisely and repeatably than in previous wind tunnel tests. This control system also allowed the rotor trim state to be maintained during transients and drift in wind tunnel flow, and through changes in IBC actuation. The ability to maintain a consistent rotor trim state was key to quickly and accurately evaluating the effect of IBC on rotor performance, vibration, noise and loads. This paper presents details of the design and implementation of the trim control system including the rotor system hardware, trim control requirements, and trim control hardware and software implementation. Results are presented showing the effect of IBC on rotor trim and dynamic response, a validation of the rotor dynamic simulation used to calculate the initial control gains and tuning of the control system, and the overall performance of the trim control system during the wind tunnel test.

Infrared Chemiluminescence Studies of Ion-Molecule Reactions in a Flowing Afterglow.

DTIC Science & Technology

1982-01-01

reaction rate constants and branching ratios have been addressed in drift tubes and flow drift systems, and the translational energy distribution of atomic...composed of about 40 thin cylindrical sections of flow tube , separated by mylar spacers and connected by precision resistors. In the region of LIF... tube radius (Albritton, 1967). For proper operation of a drift tube , ionic species of only one polarity can be present. Efficient separation of

Analysis of Active Lava Flows on Kilauea Volcano, Hawaii, Using SIR-C Radar Correlation Measurements

NASA Technical Reports Server (NTRS)

Zebker, H. A.; Rosen, P.; Hensley, S.; Mouginis-Mark, P. J.

1995-01-01

Precise eruption rates of active pahoehoe lava flows on Kilauea volcano, Hawaii, have been determined using spaceborne radar data acquired by the Space Shuttle Imaging Radar-C (SIR-C). Measurement of the rate of lava flow advance, and the determination of the volume of new material erupted in a given period of time, are among the most important observations that can be made when studying a volcano.

Model-based development of low-level control strategies for transient operation of solid oxide fuel cell systems

NASA Astrophysics Data System (ADS)

Sorrentino, Marco; Pianese, Cesare

The exploitation of an SOFC-system model to define and test control and energy management strategies is presented. Such a work is motivated by the increasing interest paid to SOFC technology by industries and governments due to its highly appealing potentialities in terms of energy savings, fuel flexibility, cogeneration, low-pollution and low-noise operation. The core part of the model is the SOFC stack, surrounded by a number of auxiliary devices, i.e. air compressor, regulating pressure valves, heat exchangers, pre-reformer and post-burner. Due to the slow thermal dynamics of SOFCs, a set of three lumped-capacity models describes the dynamic response of fuel cell and heat exchangers to any operation change. The dynamic model was used to develop low-level control strategies aimed at guaranteeing targeted performance while keeping stack temperature derivative within safe limits to reduce stack degradation due to thermal stresses. Control strategies for both cold-start and warmed-up operations were implemented by combining feedforward and feedback approaches. Particularly, the main cold-start control action relies on the precise regulation of methane flow towards anode and post-burner via by-pass valves; this strategy is combined with a cathode air-flow adjustment to have a tight control of both stack temperature gradient and warm-up time. Results are presented to show the potentialities of the proposed model-based approach to: (i) serve as a support to control strategies development and (ii) solve the trade-off between fast SOFC cold-start and avoidance of thermal-stress caused damages.

High precision locating control system based on VCM for Talbot lithography

NASA Astrophysics Data System (ADS)

Yao, Jingwei; Zhao, Lixin; Deng, Qian; Hu, Song

2016-10-01

Aiming at the high precision and efficiency requirements of Z-direction locating in Talbot lithography, a control system based on Voice Coil Motor (VCM) was designed. In this paper, we built a math model of VCM and its moving characteristic was analyzed. A double-closed loop control strategy including position loop and current loop were accomplished. The current loop was implemented by driver, in order to achieve the rapid follow of the system current. The position loop was completed by the digital signal processor (DSP) and the position feedback was achieved by high precision linear scales. Feed forward control and position feedback Proportion Integration Differentiation (PID) control were applied in order to compensate for dynamic lag and improve the response speed of the system. And the high precision and efficiency of the system were verified by simulation and experiments. The results demonstrated that the performance of Z-direction gantry was obviously improved, having high precision, quick responses, strong real-time and easily to expend for higher precision.

All optical quantum control of a spin-quantum state and ultrafast transduction into an electric current.

PubMed

Müller, K; Kaldewey, T; Ripszam, R; Wildmann, J S; Bechtold, A; Bichler, M; Koblmüller, G; Abstreiter, G; Finley, J J

2013-01-01

The ability to control and exploit quantum coherence and entanglement drives research across many fields ranging from ultra-cold quantum gases to spin systems in condensed matter. Transcending different physical systems, optical approaches have proven themselves to be particularly powerful, since they profit from the established toolbox of quantum optical techniques, are state-selective, contact-less and can be extremely fast. Here, we demonstrate how a precisely timed sequence of monochromatic ultrafast (~ 2-5 ps) optical pulses, with a well defined polarisation can be used to prepare arbitrary superpositions of exciton spin states in a semiconductor quantum dot, achieve ultrafast control of the spin-wavefunction without an applied magnetic field and make high fidelity read-out the quantum state in an arbitrary basis simply by detecting a strong (~ 2-10 pA) electric current flowing in an external circuit. The results obtained show that the combined quantum state preparation, control and read-out can be performed with a near-unity (≥97%) fidelity.

High perfomance liquid chromatography fingerprint analysis for quality control of brotowali (Tinospora crispa)

NASA Astrophysics Data System (ADS)

Syarifah, V. B.; Rafi, M.; Wahyuni, W. T.

2017-05-01

Brotowali (Tinospora crispa) is widely used in Indonesia as ingredient of herbal medicine formulation. To ensure the quality, safety, and efficacy of herbal medicine products, its chemical constituents should be continuously evaluated. High performance liquid chromatography (HPLC) fingerprint is one of powerful technique for this quality control process. In this study, HPLC fingerprint analysis method was developed for quality control of brotowali. HPLC analysis was performed in C18 column and detection was performed using photodiode array detector. The optimum mobile phase for brotowali fingerprint was acetonitrile (ACN) and 0.1% formic acid in gradient elution mode at a flow rate of 1 mL/min. The number of peaks detected in HPLC fingerprint of brotowali was 32 peaks and 23 peaks for stems and leaves, respectively. Berberine as marker compound was detected at retention time of 20.525 minutes. Evaluation of analytical performance including precision, reproducibility, and stability prove that this HPLC fingerprint analysis was reliable and could be applied for quality control of brotowali.

Chocolate Classification by an Electronic Nose with Pressure Controlled Generated Stimulation

PubMed Central

Valdez, Luis F.; Gutiérrez, Juan Manuel

2016-01-01

In this work, we will analyze the response of a Metal Oxide Gas Sensor (MOGS) array to a flow controlled stimulus generated in a pressure controlled canister produced by a homemade olfactometer to build an E-nose. The built E-nose is capable of chocolate identification between the 26 analyzed chocolate bar samples and four features recognition (chocolate type, extra ingredient, sweetener and expiration date status). The data analysis tools used were Principal Components Analysis (PCA) and Artificial Neural Networks (ANNs). The chocolate identification E-nose average classification rate was of 81.3% with 0.99 accuracy (Acc), 0.86 precision (Prc), 0.84 sensitivity (Sen) and 0.99 specificity (Spe) for test. The chocolate feature recognition E-nose gives a classification rate of 85.36% with 0.96 Acc, 0.86 Prc, 0.85 Sen and 0.96 Spe. In addition, a preliminary sample aging analysis was made. The results prove the pressure controlled generated stimulus is reliable for this type of studies. PMID:27775628

Chocolate Classification by an Electronic Nose with Pressure Controlled Generated Stimulation.

PubMed

Valdez, Luis F; Gutiérrez, Juan Manuel

2016-10-20

In this work, we will analyze the response of a Metal Oxide Gas Sensor (MOGS) array to a flow controlled stimulus generated in a pressure controlled canister produced by a homemade olfactometer to build an E-nose. The built E-nose is capable of chocolate identification between the 26 analyzed chocolate bar samples and four features recognition (chocolate type, extra ingredient, sweetener and expiration date status). The data analysis tools used were Principal Components Analysis (PCA) and Artificial Neural Networks (ANNs). The chocolate identification E-nose average classification rate was of 81.3% with 0.99 accuracy (Acc), 0.86 precision (Prc), 0.84 sensitivity (Sen) and 0.99 specificity (Spe) for test. The chocolate feature recognition E-nose gives a classification rate of 85.36% with 0.96 Acc, 0.86 Prc, 0.85 Sen and 0.96 Spe. In addition, a preliminary sample aging analysis was made. The results prove the pressure controlled generated stimulus is reliable for this type of studies.

Development of N_2O-MTV for low-speed flow and in-situ deployment to an integral effect test facility

NASA Astrophysics Data System (ADS)

André, Matthieu A.; Burns, Ross A.; Danehy, Paul M.; Cadell, Seth R.; Woods, Brian G.; Bardet, Philippe M.

2018-01-01

A molecular tagging velocity (MTV) technique is developed to non-intrusively measure velocity in an integral effect test (IET) facility simulating a high-temperature helium-cooled nuclear reactor in accident scenarios. In these scenarios, the velocities are expected to be low, on the order of 1 m/s or less, which forces special requirements on the MTV tracer selection. Nitrous oxide (N_2O) is identified as a suitable seed gas to generate NO tracers capable of probing the flow over a large range of pressure, temperature, and flow velocity. The performance of N_2O-MTV is assessed in the laboratory at temperature and pressure ranging from 295 to 781 K and 1 to 3 atm. MTV signal improves with a temperature increase, but decreases with a pressure increase. Velocity precision down to 0.004 m/s is achieved with a probe time of 40 ms at ambient pressure and temperature. Measurement precision is limited by tracer diffusion, and absorption of the tag laser beam by the seed gas. Processing by cross-correlation of single-shot images with high signal-to-noise ratio reference images improves the precision by about 10% compared to traditional single-shot image correlations. The instrument is then deployed to the IET facility. Challenges associated with heat, vibrations, safety, beam delivery, and imaging are addressed in order to successfully operate this sensitive instrument in-situ. Data are presented for an isothermal depressurized conduction cooldown. Velocity profiles from MTV reveal a complex flow transient driven by buoyancy, diffusion, and instability taking place over short (<1 s) and long (>30 min) time scales at sub-meter per second speed. The precision of the in-situ results is estimated at 0.027, 0.0095, and 0.006 m/s for a probe time of 5, 15, and 35 ms, respectively.

Evaluation of a novel wind tunnel for the measurement of the kinetics of odour emissions from piggery effluent.

PubMed

Sohn, J H; Smith, R; Yoong, E; Hudson, N; Kim, T I

2004-01-01

A novel laboratory wind tunnel, with the capability to control factors such as air flow-rate, was developed to measure the kinetics of odour emissions from liquid effluent. The tunnel allows the emission of odours and other volatiles under an atmospheric transport system similar to ambient conditions. Sensors for wind speed, temperature and humidity were installed and calibrated. To calibrate the wind tunnel, trials were performed to determine the gas recovery efficiency under different air flow-rates (ranging from 0.001 to 0.028m3/s) and gas supply rates (ranging from 2.5 to 10.0 L/min) using a standard CO gas mixture. The results have shown gas recovery efficiencies ranging from 61.7 to 106.8%, while the average result from the trials was 81.14%. From statistical analysis, it was observed that the highest, most reliable gas recovery efficiency of the tunnel was 88.9%. The values of air flow-rate and gas supply rate corresponding to the highest gas recovery efficiency were 0.028 m3/s and 10.0 L/min respectively. This study suggested that the wind tunnel would provide precise estimates of odour emission rate. However, the wind tunnel needs to be calibrated to compensate for errors caused by different air flow-rates.

Continuous-Flow Production of Injectable Liposomes via a Microfluidic Approach

PubMed Central

Zizzari, Alessandra; Bianco, Monica; Perrone, Elisabetta; Amato, Francesco; Maruccio, Giuseppe; Rendina, Filippo; Arima, Valentina

2017-01-01

Injectable liposomes are characterized by a suitable size and unique lipid mixtures, which require time-consuming and nonstraightforward production processes. The complexity of the manufacturing methods may affect liposome solubility, the phase transition temperatures of the membranes, the average particle size, and the associated particle size distribution, with a possible impact on the drug encapsulation and release. By leveraging the precise steady-state control over the mixing of miscible liquids and a highly efficient heat transfer, microfluidic technology has proved to be an effective and direct methodology to produce liposomes. This approach results particularly efficient in reducing the number of the sizing steps, when compared to standard industrial methods. Here, Microfluidic Hydrodynamic Focusing chips were produced and used to form liposomes upon tuning experimental parameters such as lipids concentration and Flow-Rate-Ratios (FRRs). Although modelling evidenced the dependence of the laminar flow on the geometric constraints and the FRR conditions, for the specific formulation investigated in this study, the lipids concentration was identified as the primary factor influencing the size of the liposomes and their polydispersity index. This was attributed to a predominance of the bending elasticity modulus over the vesiculation index in the lipid mixture used. Eventually, liposomes of injectable size were produced using microfluidic one-pot synthesis in continuous flow. PMID:29232873

A method of calibrating wind velocity sensors with a modified gas flow calibrator

NASA Technical Reports Server (NTRS)

Stump, H. P.

1978-01-01

A procedure was described for calibrating air velocity sensors in the exhaust flow of a gas flow calibrator. The average velocity in the test section located at the calibrator exhaust was verified from the mass flow rate accurately measured by the calibrator's precision sonic nozzles. Air at elevated pressures flowed through a series of screens, diameter changes, and flow straighteners, resulting in a smooth flow through the open test section. The modified system generated air velocities of 2 to 90 meters per second with an uncertainty of about two percent for speeds below 15 meters per second and four percent for the higher speeds. Wind tunnel data correlated well with that taken in the flow calibrator.

Low noise lead screw positioner

NASA Technical Reports Server (NTRS)

Perkins, Gerald S. (Inventor)

1986-01-01

A very precise and low noise lead screw positioner, for positioning a retroreflector in an interferometer is described. A gas source supplies inert pressurized gas, that flows through narrow holes into the clearance space between a nut and the lead screw. The pressurized gas keeps the nut out of contact with the screw. The gas flows axially along the clearance space, into the environment. The small amount of inert gas flowing into the environment minimizes pollution. By allowing such flow into the environment, no seals are required between the end of the nut and the screw.

Synthetic Capillaries to Control Microscopic Blood Flow

NASA Astrophysics Data System (ADS)

Sarveswaran, K.; Kurz, V.; Dong, Z.; Tanaka, T.; Penny, S.; Timp, G.

2016-02-01

Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using “live cell lithography”(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision—no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100-1000 cells, organized hierarchically to express a predictable function.

Vapourisers: Physical Principles and Classification

PubMed Central

Dhulkhed, Vithal; Shetti, Akshaya; Naik, Shraddha; Dhulkhed, Pavan

2013-01-01

Vapourisers have evolved from rudimentary inhalers to the microprocessor controlled, temperature compensated and flow sensing devices, which are universal today. The improvements in the design was influenced by the development of potent inhalational anaesthetics, unique properties of some agents, a deeper understanding of their mechanism of action, inherent flaws in the older vapourisers, mechanical problems due to thymol deposition, factors influencing their output such as temperature and pressure variations. It is important to review the principles governing the design of the vapouriser to gain insight into their working. It is fascinating to know how some of the older vapourisers, popularly used in the past, functioned. The descendant of Oxford Miniature Vapourizer, the Triservice vapouriser is still a part of the military anaesthesia draw over equipment meant for field use whereas the Copper Kettle the first precision device is the fore-runner of the Tec 6 and Aladdin cassette vapouriser. Anaesthesia trainees if exposed to draw over techniques get a deeper understanding of equipment and improved skills for disaster situations. In the recent advanced versions of the vapouriser a central processing unit in the anaesthetic machine controls the operation by continuously monitoring and adjusting fresh gas flow through the vapouriser to maintain desired concentration of the vapour. PMID:24249878

More Efficient Power Conversion for EVs: Gallium-Nitride Advanced Power Semiconductor and Packaging

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

None

2010-02-01

Broad Funding Opportunity Announcement Project: Delphi is developing power converters that are smaller and more energy efficient, reliable, and cost-effective than current power converters. Power converters rely on power transistors which act like a very precisely controlled on-off switch, controlling the electrical energy flowing through an electrical circuit. Most power transistors today use silicon (Si) semiconductors. However, Delphi is using semiconductors made with a thin layer of gallium-nitride (GaN) applied on top of the more conventional Si material. The GaN layer increases the energy efficiency of the power transistor and also enables the transistor to operate at much higher temperatures,more » voltages, and power-density levels compared to its Si counterpart. Delphi is packaging these high-performance GaN semiconductors with advanced electrical connections and a cooling system that extracts waste heat from both sides of the device to further increase the device’s efficiency and allow more electrical current to flow through it. When combined with other electronic components on a circuit board, Delphi’s GaN power transistor package will help improve the overall performance and cost-effectiveness of HEVs and EVs.« less

Improvement of a Pneumatic Control Valve with Self-Holding Function

NASA Astrophysics Data System (ADS)

Dohta, Shujiro; Akagi, Tetsuya; Kobayashi, Wataru; Shimooka, So; Masago, Yusuke

2017-10-01

The purpose of this study is to develop a small-sized, lightweight and low-cost control valve with low energy consumption and to apply it to the assistive system. We have developed some control valves; a tiny on/off valve using a vibration motor, and an on/off valve with self-holding function. We have also proposed and tested the digital servo valve with self-holding function using permanent magnets and a small-sized servo motor. In this paper, in order to improve the valve, an analytical model of the digital servo valve is proposed. And the simulated results by using the analytical model and identified parameters were compared with the experimental results. Then, the improved digital servo valve was designed based on the calculated results and tested. As a result, we realized the digital servo valve that can control the flow rate more precisely while maintaining its volume and weight compared with the previous valve. As an application of the improved valve, a position control system of rubber artificial muscle was built and the position control was performed successfully.

A Novel Hybrid Error Criterion-Based Active Control Method for on-Line Milling Vibration Suppression with Piezoelectric Actuators and Sensors

PubMed Central

Zhang, Xingwu; Wang, Chenxi; Gao, Robert X.; Yan, Ruqiang; Chen, Xuefeng; Wang, Shibin

2016-01-01

Milling vibration is one of the most serious factors affecting machining quality and precision. In this paper a novel hybrid error criterion-based frequency-domain LMS active control method is constructed and used for vibration suppression of milling processes by piezoelectric actuators and sensors, in which only one Fast Fourier Transform (FFT) is used and no Inverse Fast Fourier Transform (IFFT) is involved. The correction formulas are derived by a steepest descent procedure and the control parameters are analyzed and optimized. Then, a novel hybrid error criterion is constructed to improve the adaptability, reliability and anti-interference ability of the constructed control algorithm. Finally, based on piezoelectric actuators and acceleration sensors, a simulation of a spindle and a milling process experiment are presented to verify the proposed method. Besides, a protection program is added in the control flow to enhance the reliability of the control method in applications. The simulation and experiment results indicate that the proposed method is an effective and reliable way for on-line vibration suppression, and the machining quality can be obviously improved. PMID:26751448

Actuated forebody strake controls for the F-18 high alpha research vehicle

NASA Technical Reports Server (NTRS)

Murri, Daniel G.; Shah, Gautam H.; Dicarlo, Daniel J.; Trilling, Todd W.

1993-01-01

A series of ground-based studies have been conducted to develop actuated forebody strake controls for flight test evaluations using the NASA F-18 High-Alpha Research Vehicle. The actuated forebody strake concept has been designed to provide increased levels of yaw control at high angles of attack where conventional rudders become ineffective. Results are presented from tests conducted with the flight-test strake design, including static and dynamic wind-tunnel tests, transonic wind-tunnel tests, full-scale wind-tunnel tests, pressure surveys, and flow visualization tests. Results from these studies show that a pair of conformal actuated forebody strakes applied to the F-18 HARV can provide a powerful and precise yaw control device at high angles of attack. The preparations for flight testing are described, including the fabrication of flight hardware and the development of aircraft flight control laws. The primary objectives of the flight tests are to provide flight validation of the groundbased studies and to evaluate the use of this type of control to enhance fighter aircraft maneuverability.

System precisely controls oscillation of vibrating mass

NASA Technical Reports Server (NTRS)

Hancock, D. J.

1967-01-01

System precisely controls the sinusoidal amplitude of a vibrating mechanical mass. Using two sets of coils, the system regulates the drive signal amplitude at the precise level to maintain the mechanical mass when it reaches the desired vibration amplitude.

[HPLC fingerprint chromatogram of Polygonum multiflorum from Guizhou].

PubMed

Li, Yan; Wang, Hui-Juan; Lin, Bing; Zhao, Zhi; Zhou, Ying

2012-12-01

To establish the fingerprint of Polygonum multiflorum from Guizhou and provide a standard for its quality control. HPLC analysis was performed on Agillent ZABAX-C18 (4.6 mm x 250 mm, 5 microm), gradient eluted composed of acetonitrile-0.4% water solution of phosphoric acid. Column temperature was set at 25 degrees C and the flow rate was 1 mL/min. The detection wavelength was 280 nm and the analysis time was 60 min. 9 common peaks were identified. The RSD of the relative retention time and the relative peak area were less than 3% in analyzing its precision, stability and repeatability of the common peaks, and the similarity of the 16 batches of sample was more than 0.9. The method is simple and reliable, and it can provide a standard and guidance for quality control of Polygonum multiflorum.

CARMENES: an overview six months after first light

NASA Astrophysics Data System (ADS)

Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Mundt, R.; Reiners, A.; Ribas, I.; Seifert, W.; Abril, M.; Aceituno, J.; Alonso-Floriano, F. J.; Anwand-Heerwart, H.; Azzaro, M.; Bauer, F.; Barrado, D.; Becerril, S.; Bejar, V. J. S.; Benitez, D.; Berdinas, Z. M.; Brinkmöller, M.; Cardenas, M. C.; Casal, E.; Claret, A.; Colomé, J.; Cortes-Contreras, M.; Czesla, S.; Doellinger, M.; Dreizler, S.; Feiz, C.; Fernandez, M.; Ferro, I. M.; Fuhrmeister, B.; Galadi, D.; Gallardo, I.; Gálvez-Ortiz, M. C.; Garcia-Piquer, A.; Garrido, R.; Gesa, L.; Gómez Galera, V.; González Hernández, J. I.; Gonzalez Peinado, R.; Grözinger, U.; Guàrdia, J.; Guenther, E. W.; de Guindos, E.; Hagen, H.-J.; Hatzes, A. P.; Hauschildt, P. H.; Helmling, J.; Henning, T.; Hermann, D.; Hernández Arabi, R.; Hernández Castaño, L.; Hernández Hernando, F.; Herrero, E.; Huber, A.; Huber, K. F.; Huke, P.; Jeffers, S. V.; de Juan, E.; Kaminski, A.; Kehr, M.; Kim, M.; Klein, R.; Klüter, J.; Kürster, M.; Lafarga, M.; Lara, L. M.; Lamert, A.; Laun, W.; Launhardt, R.; Lemke, U.; Lenzen, R.; Llamas, M.; Lopez del Fresno, M.; López-Puertas, M.; López-Santiago, J.; Lopez Salas, J. F.; Magan Madinabeitia, H.; Mall, U.; Mandel, H.; Mancini, L.; Marin Molina, J. A.; Maroto Fernández, D.; Martín, E. L.; Martín-Ruiz, S.; Marvin, C.; Mathar, R. J.; Mirabet, E.; Montes, D.; Morales, J. C.; Morales Muñoz, R.; Nagel, E.; Naranjo, V.; Nowak, G.; Palle, E.; Panduro, J.; Passegger, V. M.; Pavlov, A.; Pedraz, S.; Perez, E.; Pérez-Medialdea, D.; Perger, M.; Pluto, M.; Ramón, A.; Rebolo, R.; Redondo, P.; Reffert, S.; Reinhart, S.; Rhode, P.; Rix, H.-W.; Rodler, F.; Rodríguez, E.; Rodríguez López, C.; Rohloff, R. R.; Rosich, A.; Sanchez Carrasco, M. A.; Sanz-Forcada, J.; Sarkis, P.; Sarmiento, L. F.; Schäfer, S.; Schiller, J.; Schmidt, C.; Schmitt, J. H. M. M.; Schöfer, P.; Schweitzer, A.; Shulyak, D.; Solano, E.; Stahl, O.; Storz, C.; Tabernero, H. M.; Tala, M.; Tal-Or, L.; Ulbrich, R.-G.; Veredas, G.; Vico Linares, J. I.; Vilardell, F.; Wagner, K.; Winkler, J.; Zapatero Osorio, M.-R.; Zechmeister, M.; Ammler-von Eiff, M.; Anglada-Escudé, G.; del Burgo, C.; Garcia-Vargas, M. L.; Klutsch, A.; Lizon, J.-L.; Lopez-Morales, M.; Ofir, A.; Pérez-Calpena, A.; Perryman, M. A. C.; Sánchez-Blanco, E.; Strachan, J. B. P.; Stürmer, J.; Suárez, J. C.; Trifonov, T.; Tulloch, S. M.; Xu, W.

2016-08-01

The CARMENES instrument is a pair of high-resolution (R> 80,000) spectrographs covering the wavelength range from 0.52 to 1.71 μm, optimized for precise radial velocity measurements. It was installed and commissioned at the 3.5m telescope of the Calar Alto observatory in Southern Spain in 2015. The first large science program of CARMENES is a survey of 300 M dwarfs, which started on Jan 1, 2016. We present an overview of all subsystems of CARMENES (front end, fiber system, visible-light spectrograph, near-infrared spectrograph, calibration units, etalons, facility control, interlock system, instrument control system, data reduction pipeline, data flow, and archive), and give an overview of the assembly, integration, verification, and commissioning phases of the project. We show initial results and discuss further plans for the scientific use of CARMENES.

Development of variable-width ribbon heating elements for liquid-metal and gas-cooled fast breeder reactor fuel-pin simulators

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

McCulloch, R.W.; Post, D.W.; Lovell, R.T.

1981-04-01

Variable-width ribbon heating elements that provide a chopped-cosine variable heat flux profile have been fabricated for fuel pin simulators used in test loops by the Breeder Reactor Program Thermal-Hydraulic Out-of-Reactor Safety test facility and the Gas-Cooled Fast Breeder Reactor-Core Flow Test Loop. Thermal, mechanical, and electrical design considerations are used to derive an analytical expression that precisely describes ribbon contour in terms of the major fabrication parameters. These parameters are used to generate numerical control tapes that control ribbon cutting and winding machines. Infrared scanning techniques are developed to determine the optimum transient thermal profile of the coils and relatemore » this profile to that generated by the coils in completed fuel pin simulators.« less

Simulation evaluation of TIMER, a time-based, terminal air traffic, flow-management concept

NASA Technical Reports Server (NTRS)

Credeur, Leonard; Capron, William R.

1989-01-01

A description of a time-based, extended terminal area ATC concept called Traffic Intelligence for the Management of Efficient Runway scheduling (TIMER) and the results of a fast-time evaluation are presented. The TIMER concept is intended to bridge the gap between today's ATC system and a future automated time-based ATC system. The TIMER concept integrates en route metering, fuel-efficient cruise and profile descents, terminal time-based sequencing and spacing together with computer-generated controller aids, to improve delivery precision for fuller use of runway capacity. Simulation results identify and show the effects and interactions of such key variables as horizon of control location, delivery time error at both the metering fix and runway threshold, aircraft separation requirements, delay discounting, wind, aircraft heading and speed errors, and knowledge of final approach speed.

A high precision dual feedback pump for unsteady perfusion of small organs.

PubMed

Sutton, D W; Mead, E H; Schmid-Schönbein, G W

1989-01-01

A dynamic pump system is described for perfusion of small organs with whole blood. The pump system was designed with the following aims: Very low flowrates to perfuse single organs in small rodents; high dynamic response for pressure or flow to permit experimenting with a harmonic signal at frequencies up to 20 Hz or by way of sharp step transients in less than 10 msec; high precision to allow detection of fine physiological details, and minimum blood cell trauma or cell activation by use of a piston principle. Representative pressure-flow curves are shown for the rat gracilis muscle after vasodilation. The curves are highly reproducible and serve as a complimentary dataset for microvascular observations in the same organ.

Photographic techniques for enhancing ERTS MSS data for geologic information

NASA Technical Reports Server (NTRS)

Yost, E.; Geluso, W.; Anderson, R.

1974-01-01

Satellite multispectral black-and-white photographic negatives of Luna County, New Mexico, obtained by ERTS on 15 August and 2 September 1973, were precisely reprocessed into positive images and analyzed in an additive color viewer. In addition, an isoluminous (uniform brightness) color rendition of the image was constructed. The isoluminous technique emphasizes subtle differences between multispectral bands by greatly enhancing the color of the superimposed composite of all bands and eliminating the effects of brightness caused by sloping terrain. Basaltic lava flows were more accurately displayed in the precision processed multispectral additive color ERTS renditions than on existing state geological maps. Malpais lava flows and small basaltic occurrences not appearing on existing geological maps were identified in ERTS multispectral color images.

Characterization of a Combined CARS and Interferometric Rayleigh Scattering System

NASA Technical Reports Server (NTRS)

Tedder, Sarah A.; Bivolaru, Daniel; Danehy, Paul M.; Weikl, M. C.; Beyrau, F.; Seeger, T.; Cutler, Andrew D.

2007-01-01

This paper describes the characterization of a combined Coherent anti-Stokes Raman Spectroscopy and Interferometric Rayleigh Scattering (CARS-IRS) system by reporting the accuracy and precision of the measurements of temperature, species mole fraction of N2, O2, and H2, and two-components of velocity. A near-adiabatic H2-air Hencken burner flame was used to provide known properties for measurements made with the system. The measurement system is also demonstrated in a small-scale Mach 1.6 H2-air combustion-heated supersonic jet with a co-flow of H2. The system is found to have a precision that is sufficient to resolve fluctuations of flow properties in the mixing layer of the jet.

Tidal current energy potential of Nalón river estuary assessment using a high precision flow model

NASA Astrophysics Data System (ADS)

Badano, Nicolás; Valdés, Rodolfo Espina; Álvarez, Eduardo Álvarez

2018-05-01

Obtaining energy from tide currents in onshore locations is of great interest due to the proximity to the points of consumption. This opens the door to the feasibility of new installations based on hydrokinetic microturbines even in zones of moderate speed. In this context, the accuracy of energy predictions based on hydrodynamic models is of paramount importance. This research presents a high precision methodology based on a multidimensional hydrodynamic model that is used to study the energetic potential in estuaries. Moreover, it is able to estimate the flow variations caused by microturbine installations. The paper also shows the results obtained from the application of the methodology in a study of the Nalón river mouth (Asturias, Spain).

Isentropic fluid dynamics in a curved pipe

NASA Astrophysics Data System (ADS)

Colombo, Rinaldo M.; Holden, Helge

2016-10-01

In this paper we study isentropic flow in a curved pipe. We focus on the consequences of the geometry of the pipe on the dynamics of the flow. More precisely, we present the solution of the general Cauchy problem for isentropic fluid flow in an arbitrarily curved, piecewise smooth pipe. We consider initial data in the subsonic regime, with small total variation about a stationary solution. The proof relies on the front-tracking method and is based on [1].

Spike-timing dependent inhibitory plasticity to learn a selective gating of backpropagating action potentials.

PubMed

Wilmes, Katharina Anna; Schleimer, Jan-Hendrik; Schreiber, Susanne

2017-04-01

Inhibition is known to influence the forward-directed flow of information within neurons. However, also regulation of backward-directed signals, such as backpropagating action potentials (bAPs), can enrich the functional repertoire of local circuits. Inhibitory control of bAP spread, for example, can provide a switch for the plasticity of excitatory synapses. Although such a mechanism is possible, it requires a precise timing of inhibition to annihilate bAPs without impairment of forward-directed excitatory information flow. Here, we propose a specific learning rule for inhibitory synapses to automatically generate the correct timing to gate bAPs in pyramidal cells when embedded in a local circuit of feedforward inhibition. Based on computational modeling of multi-compartmental neurons with physiological properties, we demonstrate that a learning rule with anti-Hebbian shape can establish the required temporal precision. In contrast to classical spike-timing dependent plasticity of excitatory synapses, the proposed inhibitory learning mechanism does not necessarily require the definition of an upper bound of synaptic weights because of its tendency to self-terminate once annihilation of bAPs has been reached. Our study provides a functional context in which one of the many time-dependent learning rules that have been observed experimentally - specifically, a learning rule with anti-Hebbian shape - is assigned a relevant role for inhibitory synapses. Moreover, the described mechanism is compatible with an upregulation of excitatory plasticity by disinhibition. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

High-resolution flying-PIV with optical fiber laser delivery

NASA Astrophysics Data System (ADS)

Weichselbaum, Noah A.; André, Matthieu A.; Rahimi-Abkenar, Morteza; Manzari, Majid T.; Bardet, Philippe M.

2016-05-01

Implementation of non-intrusive optical measurement techniques, such as particle image velocimetry (PIV), in harsh environments requires specialized techniques for introducing controlled laser sheets to the region of interest. Large earthquake shake tables are a particularly challenging environment. Lasers must be mounted away from the table, and the laser sheet has to be delivered precisely and stably to the measurement station. Here, high-power multi-mode step-index fiber optics enable introduction of light from an Nd:YLF pulsed laser to a remote test section. Such lasers are suitable for coupling to optical fibers, which presents a portable, flexible, and safe manner to deliver a PIV light sheet. Best practices for their implementation are reviewed. Particular attention is focused on obtaining a collimated beam of acceptable quality at the output of the fiber. To achieve high spatial resolution, the PIV camera is directly mounted on the moving shake table with care to minimize its vibrations. A special arrangement of PIV planes is deployed for precise in-situ PIV alignment and to monitor and account for residual structure vibrations and beam wandering. The design of the instruments is detailed. Here, an experimental facility for the study of nuclear fuel bundle response to seismic forcing near prototypical conditions is instrumented. Only through integration of a high-resolution flying-PIV system can velocity fields be acquired. Data indicate that in the presence of a mean axial flow, a secondary oscillatory flow develops as the bundle oscillates. Instantaneous, phase-averaged, and fluctuating velocity fields illustrate this phenomenon.

Oxidative induction time -- A review of DSC experimental effects

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

Blaine, R.L.; Lundgren, C.J.; Harris, M.B.

1997-12-31

Over the past several years, a number of ASTM committees have explored a wide variety of experimental parameters affecting the oxidative induction time (OIT) test method in an attempt to improve its intra- and inter-laboratory precision. These studies have identified test temperature precision as a key parameter affecting OIT precision. Other parameters of importance are oxygen flow rate, specimen size, specimen pan type, oxygen pressure and catalyst effects. The work of Kuck, Bowmer, Riga, Tikuisis and Thomas are reviewed as well as the collective work of ASTM Committees E37, D2, D9 and D35.

The progress on time & frequency during the past 5 decades

NASA Astrophysics Data System (ADS)

Wang, Zheng-Ming

2002-06-01

The number and variety of applications using precise timing are astounding and increasing along with the new technology in communication, computer science, space science as well as in other fields. The world has evolved into the information age, and precise timing is at the heart of managing the flow of that information, which prompts the progress on precise timing itself rapidly. The development of time scales, UT1 determination, frequency standards, time transfer and the time dissemination for the past half century in the world and in China are described in this paper. The expectation in this field is discussed.

Implementing oxygen control in chip-based cell and tissue culture systems.

PubMed

Oomen, Pieter E; Skolimowski, Maciej D; Verpoorte, Elisabeth

2016-09-21

Oxygen is essential in the energy metabolism of cells, as well as being an important regulatory parameter influencing cell differentiation and function. Interest in precise oxygen control for in vitro cultures of tissues and cells continues to grow, especially with the emergence of the organ-on-a-chip and the desire to emulate in vivo conditions. This was recently discussed in this journal in a Critical Review by Brennan et al. (Lab Chip (2014). DOI: ). Microfluidics can be used to introduce flow to facilitate nutrient supply to and waste removal from in vitro culture systems. Well-defined oxygen gradients can also be established. However, cells can quickly alter the oxygen balance in their vicinity. In this Tutorial Review, we expand on the Brennan paper to focus on the implementation of oxygen analysis in these systems to achieve continuous monitoring. Both electrochemical and optical approaches for the integration of oxygen monitoring in microfluidic tissue and cell culture systems will be discussed. Differences in oxygen requirements from one organ to the next are a challenging problem, as oxygen delivery is limited by its uptake into medium. Hence, we discuss the factors determining oxygen concentrations in solutions and consider the possible use of artificial oxygen carriers to increase dissolved oxygen concentrations. The selection of device material for applications requiring precise oxygen control is discussed in detail, focusing on oxygen permeability. Lastly, a variety of devices is presented, showing the diversity of approaches that can be employed to control and monitor oxygen concentrations in in vitro experiments.

A Formalisation of Adaptable Pervasive Flows

NASA Astrophysics Data System (ADS)

Bucchiarone, Antonio; Lafuente, Alberto Lluch; Marconi, Annapaola; Pistore, Marco

Adaptable Pervasive Flows is a novel workflow-based paradigm for the design and execution of pervasive applications, where dynamic workflows situated in the real world are able to modify their execution in order to adapt to changes in their environment. In this paper, we study a formalisation of such flows by means of a formal flow language. More precisely, we define APFoL (Adaptable Pervasive Flow Language) and formalise its textual notation by encoding it in Blite, a formalisation of WS-BPEL. The encoding in Blite equips the language with a formal semantics and enables the use of automated verification techniques. We illustrate the approach with an example of a Warehouse Case Study.

Evaluation of the FIR Example using Xilinx Vivado High-Level Synthesis Compiler

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

Jin, Zheming; Finkel, Hal; Yoshii, Kazutomo

Compared to central processing units (CPUs) and graphics processing units (GPUs), field programmable gate arrays (FPGAs) have major advantages in reconfigurability and performance achieved per watt. This development flow has been augmented with high-level synthesis (HLS) flow that can convert programs written in a high-level programming language to Hardware Description Language (HDL). Using high-level programming languages such as C, C++, and OpenCL for FPGA-based development could allow software developers, who have little FPGA knowledge, to take advantage of the FPGA-based application acceleration. This improves developer productivity and makes the FPGA-based acceleration accessible to hardware and software developers. Xilinx Vivado HLSmore » compiler is a high-level synthesis tool that enables C, C++ and System C specification to be directly targeted into Xilinx FPGAs without the need to create RTL manually. The white paper [1] published recently by Xilinx uses a finite impulse response (FIR) example to demonstrate the variable-precision features in the Vivado HLS compiler and the resource and power benefits of converting floating point to fixed point for a design. To get a better understanding of variable-precision features in terms of resource usage and performance, this report presents the experimental results of evaluating the FIR example using Vivado HLS 2017.1 and a Kintex Ultrascale FPGA. In addition, we evaluated the half-precision floating-point data type against the double-precision and single-precision data type and present the detailed results.« less

Low-Amplitude Topographic Features and Textures on the Moon: Initial Results from Detrended Lunar Orbiter Laser Altimeter (LOLA) Topography

NASA Technical Reports Server (NTRS)

Kreslavsky, Mikhail A.; Head, James W.; Neumann, Gregory A.; Zuber, Maria T.; Smith, David E.

2016-01-01

Global lunar topographic data derived from ranging measurements by the Lunar Orbiter Laser Altimeter (LOLA) onboard LRO mission to the Moon have extremely high vertical precision. We use detrended topography as a means for utilization of this precision in geomorphological analysis. The detrended topography was calculated as a difference between actual topography and a trend surface defined as a median topography in a circular sliding window. We found that despite complicated distortions caused by the non-linear nature of the detrending procedure, visual inspection of these data facilitates identification of low-amplitude gently-sloping geomorphic features. We present specific examples of patterns of lava flows forming the lunar maria and revealing compound flow fields, a new class of lava flow complex on the Moon. We also highlight the identification of linear tectonic features that otherwise are obscured in the images and topographic data processed in a more traditional manner.

Automation of flow injection gas diffusion-ion chromatography for the nanomolar determination of methylamines and ammonia in seawater and atmospheric samples

PubMed Central

Gibb, Stuart W.; Wood, John W.; Fauzi, R.; Mantoura, C.

1995-01-01

The automation and improved design and performance of Flow Injection Gas Diffusion-Ion Chromatography (FIGD-IC), a novel technique for the simultaneous analysis of trace ammonia (NH3) and methylamines (MAs) in aqueous media, is presented. Automated Flow Injection Gas Diffusion (FIGD) promotes the selective transmembrane diffusion of MAs and NH3 from aqueous sample under strongly alkaline (pH > 12, NaOH), chelated (EDTA) conditions into a recycled acidic acceptor stream. The acceptor is then injected onto an ion chromatograph where NH3 and the MAs are fully resolved as their cations and detected conductimetrically. A versatile PC interfaced control unit and data capture unit (DCU) are employed in series to direct the selonoid valve switching sequence, IC operation and collection of data. Automation, together with other modifications improved both linearily (R2 > 0.99 MAs 0-100 nM, NH3 0-1000 nM) and precision (<8%) of FIGD-IC at nanomolar concentrations, compared with the manual procedure. The system was successfully applied to the determination of MAs and NH3 in seawater and in trapped particulate and gaseous atmospheric samples during an oceanographic research cruise. PMID:18925047

Continuous inertial microparticle and blood cell separation in straight channels with local microstructures.

PubMed

Wu, Zhenlong; Chen, Yu; Wang, Moran; Chung, Aram J

2016-02-07

Fluid inertia which has conventionally been neglected in microfluidics has been gaining much attention for particle and cell manipulation because inertia-based methods inherently provide simple, passive, precise and high-throughput characteristics. Particularly, the inertial approach has been applied to blood separation for various biomedical research studies mainly using spiral microchannels. For higher throughput, parallelization is essential; however, it is difficult to realize using spiral channels because of their large two dimensional layouts. In this work, we present a novel inertial platform for continuous sheathless particle and blood cell separation in straight microchannels containing microstructures. Microstructures within straight channels exert secondary flows to manipulate particle positions similar to Dean flow in curved channels but with higher controllability. Through a balance between inertial lift force and microstructure-induced secondary flow, we deterministically position microspheres and cells based on their sizes to be separated downstream. Using our inertial platform, we successfully sorted microparticles and fractionized blood cells with high separation efficiencies, high purities and high throughputs. The inertial separation platform developed here can be operated to process diluted blood with a throughput of 10.8 mL min(-1)via radially arrayed single channels with one inlet and two rings of outlets.

A supercritical airfoil experiment

NASA Technical Reports Server (NTRS)

Mateer, G. G.; Seegmiller, H. L.; Hand, L. A.; Szodruck, J.

1994-01-01

The purpose of this investigation is to provide a comprehensive data base for the validation of numerical simulations. The objective of the present paper is to provide a tabulation of the experimental data. The data were obtained in the two-dimensional, transonic flowfield surrounding a supercritical airfoil. A variety of flows were studied in which the boundary layer at the trailing edge of the model was either attached or separated. Unsteady flows were avoided by controlling the Mach number and angle of attack. Surface pressures were measured on both the model and wind tunnel walls, and the flowfield surrounding the model was documented using a laser Doppler velocimeter (LDV). Although wall interference could not be completely eliminated, its effect was minimized by employing the following techniques. Sidewall boundary layers were reduced by aspiration, and upper and lower walls were contoured to accommodate the flow around the model and the boundary-layer growth on the tunnel walls. A data base with minimal interference from a tunnel with solid walls provides an ideal basis for evaluating the development of codes for the transonic speed range because the codes can include the wall boundary conditions more precisely than interference connections can be made to the data sets.

A Microfluidic System with Surface Patterning for Investigating Cavitation Bubble(s)-Cell Interaction and the Resultant Bioeffects at the Single-cell Level.

PubMed

Li, Fenfang; Yuan, Fang; Sankin, Georgy; Yang, Chen; Zhong, Pei

2017-01-10

In this manuscript, we first describe the fabrication protocol of a microfluidic chip, with gold dots and fibronectin-coated regions on the same glass substrate, that precisely controls the generation of tandem bubbles and individual cells patterned nearby with well-defined locations and shapes. We then demonstrate the generation of tandem bubbles by using two pulsed lasers illuminating a pair of gold dots with a few-microsecond time delay. We visualize the bubble-bubble interaction and jet formation by high-speed imaging and characterize the resultant flow field using particle image velocimetry (PIV). Finally, we present some applications of this technique for single cell analysis, including cell membrane poration with macromolecule uptake, localized membrane deformation determined by the displacements of attached integrin-binding beads, and intracellular calcium response from ratiometric imaging. Our results show that a fast and directional jetting flow is produced by the tandem bubble interaction, which can impose a highly localized shear stress on the surface of a cell grown in close proximity. Furthermore, different bioeffects can be induced by altering the strength of the jetting flow by adjusting the standoff distance from the cell to the tandem bubbles.

Photoinitated charge separation in a hybrid titanium dioxide metalloporphyrin peptide material

NASA Astrophysics Data System (ADS)

Fry, H. Christopher; Liu, Yuzi; Dimitrijevic, Nada M.; Rajh, Tijana

2014-08-01

In natural systems, electron flow is mediated by proteins that spatially organize donor and acceptor molecules with great precision. Achieving this guided, directional flow of information is a desirable feature in photovoltaic media. Here, we design self-assembled peptide materials that organize multiple electronic components capable of performing photoinduced charge separation. Two peptides, c16-AHL3K3-CO2H and c16-AHL3K9-CO2H, self-assemble into fibres and provide a scaffold capable of binding a metalloporphyrin via histidine axial ligation and mineralize titanium dioxide (TiO2) on the lysine-rich surface of the resulting fibrous structures. Electron paramagnetic resonance studies of this self-assembled material under continuous light excitation demonstrate charge separation induced by excitation of the metalloporphyrin and mediated by the peptide assembly structure. This approach to dye-sensitized semiconducting materials offers a means to spatially control the dye molecule with respect to the semiconducting material through careful, strategic peptide design.

A "Dual-acceptor Channel" Membraneless Gas-diffusion Unit for Simultaneous Determination of Ethanol and Acetaldehyde in Liquors Using Reverse Flow Injection.

PubMed

Choengchan, Nathawut; Poontong, Bangerdsuk; Mathaweesansurn, Arjnarong; Maneerat, Noppadol; Motomizu, Shoji; Ratanawimarnwong, Nuanlaor; Nacapricha, Duangjai

2018-01-01

A new design of membraneless gas-diffusion unit with dual acceptor channels for separation, collection and simultaneous determination of two volatile analytes in liquid sample is presented. The unit is comprised of three parallel channels in a closed module. A sample is aspirated into the central channel and two kinds of reagents are introduced into the other two channels. Two analytes are isolated from the sample matrix by diffusion into head-space and absorbed into the specific reagents. Non-absorbed vapor is released by opening the programmable controlled lid. The unit was applied to liquors for measurement of ethanol and acetaldehyde using reverse flow injection. Dichromate and nitroprusside were exploited as reagents for colorimetric detection of ethanol and acetaldehyde, respectively. Good linearity ranges (r 2 >0.99) with high precision (RSD <2%) and high accuracy (recovery: 90 - 105%) were achieved. The results were compared to the results by GC-FID and no significant difference was observed by paired t-test (95% confidence).

Microfluidics for producing poly (lactic-co-glycolic acid)-based pharmaceutical nanoparticles.

PubMed

Li, Xuanyu; Jiang, Xingyu

2017-12-24

Microfluidic chips allow the rapid production of a library of nanoparticles (NPs) with distinct properties by changing the precursors and the flow rates, significantly decreasing the time for screening optimal formulation as carriers for drug delivery compared to conventional methods. The batch-to-batch reproducibility which is essential for clinical translation is achieved by precisely controlling the precursors and the flow rate, regardless of operators. Poly (lactic-co-glycolic acid) (PLGA) is the most widely used Food and Drug Administration (FDA)-approved biodegradable polymers. Researchers often combine PLGA with lipids or amphiphilic molecules to assemble into a core/shell structure to exploit the potential of PLGA-based NPs as powerful carriers for cancer-related drug delivery. In this review, we discuss the advantages associated with microfluidic chips for producing PLGA-based functional nanocomplexes for drug delivery. These laboratory-based methods can readily scale up to provide sufficient amount of PLGA-based NPs in microfluidic chips for clinical studies and industrial-scale production. Copyright © 2017. Published by Elsevier B.V.

On-chip generation of microbubbles as a practical technology for manufacturing contrast agents for ultrasonic imaging

PubMed Central

Hettiarachchi, Kanaka; Talu, Esra; Longo, Marjorie L.; Dayton, Paul A.; Lee, Abraham P.

2007-01-01

This paper presents a new manufacturing method to generate monodisperse microbubble contrast agents with polydispersity index (σ) values of <2% through microfluidic flow-focusing. Micron-sized lipid shell-based perfluorocarbon (PFC) gas microbubbles for use as ultrasound contrast agents were produced using this method. The poly(dimethylsiloxane) (PDMS)-based devices feature expanding nozzle geometry with a 7 μm orifice width, and are robust enough for consistent production of microbubbles with runtimes lasting several hours. With high-speed imaging, we characterized relationships between channel geometry, liquid flow rate Q, and gas pressure P in controlling bubble sizes. By a simple optimization of the channel geometry and Q and P, bubbles with a mean diameter of <5 μm can be obtained, ideal for various ultrasonic imaging applications. This method demonstrates the potential of microfluidics as an efficient means for custom-designing ultrasound contrast agents with precise size distributions, different gas compositions and new shell materials for stabilization, and for future targeted imaging and therapeutic applications. PMID:17389962

Braking and cornering studies on an air cushion landing system

NASA Technical Reports Server (NTRS)

Daugherty, R. H.

1983-01-01

An experimental investigation was conducted to evaluate several concepts for braking and steering a vehicle equipped with an air cushion landing system (ACLS). The investigation made use of a modified airboat equipped with an ACLS. Braking concepts were characterized by the average deceleration of the vehicle. Reduced lobe flow and cavity venting braking concepts were evaluated in this program. The cavity venting braking concept demonstrated the best performance, producing decelerations on the test vehicle on the same order as moderate braking with conventional wheel brakes. Steering concepts were evaluated by recording the path taken while attempting to follow a prescribed maneuver. The steering concepts evaluated included using rudders only, using differential lobe flow, and using rudders combined with a lightly loaded, nonsteering center wheel. The latter concept proved to be the most accurate means of steering the vehicle on the ACLS, producing translational deviations two to three times higher than those from conventional nose-gear steering. However, this concept was still felt to provide reasonably precise steering control for the ACLS-equipped vehicle.

Preferential pathways in complex fracture systems and their influence on large scale transport

NASA Astrophysics Data System (ADS)

Willmann, M.; Mañé, R.; Tyukhova, A.

2017-12-01

Many subsurface applications in complex fracture systems require large-scale predictions. Precise predictions are difficult because of the existence of preferential pathways at different scales. The intrinsic complexity of fracture systems increases within fractured sedimentary formations, because also the coupling of fractures and matrix has to be taken into account. This interplay of fracture system and the sedimentary matrix is strongly controlled by the actual fracture aperture of an individual fracture. And an effective aperture cannot be easily be determined because of the preferential pathways along the fracture plane. We investigate the influence of these preferential pathways on large scale solute transport and upscale the aperture. By explicitly modeling flow and particle tracking in individual fractures, we develop a new effective transport aperture, which is weighted by the aperture along the preferential paths, a Lagrangian aperture. We show that this new aperture is consistently larger than existing definitions of effective flow and transport apertures. Finally, we apply our results to a fractured sedimentary formation in Northern Switzerland.

[Determination of trace amounts of zinc in nickel electrolyte by flow injection on-line enrichment].

PubMed

Zhou, Z; Wang, Y; Dong, Z; Tong, K; Guo, X; Guo, X

1999-10-01

A method for the determination of trace amount of zinc in nickel electrolyte utilizing the flow injection on-line enrichment technique is reported in this paper. Atomic absorption spectrometer was used as detector. Zinc was separated from large amounts of nickel andother components in the electrolyte by absorption its chlorocomplex on a mini-column packed with strongly basic anion exchangers. It was found that sodium chloride containing in the electrolyte offered a sufficient chloride concentration needed for the formation of the zinc chlorocomplex and thus no additional reagent was required for the determination. The throughput of the method is 30 determinations per hour. The detection limit of the method is 0.002 microg x mL(-1) and the precision is 1.9% (RSD). The proposed method is rapid and cost-effective. It has been used for almost three years in the quality control of the electrolyte in the factory with great success.

Simultaneous determination of six active components by a single standard to determine multicomponents combined with fingerprint analysis for the quality control of Rhizoma Chuanxiong.

PubMed

He, Yufei; Li, Qing; Bi, Kaishun

2015-04-01

To control the quality of Rhizoma Chuanxiong, a method based on high-performance liquid chromatography method coupled with diode array detection was developed for the quantitative analysis of six active ingredients using a single standard to determine multi-components and chemical fingerprint analysis for the first time. The separation was performed on an Agilent Zorbax SB-C18 column by gradient elution with methanol and aqueous phase (containing 0.5% glacial acetic acid) at a flow rate of 1.0 mL/min. The UV wavelength was set at 274 nm. This assay was fully validated with respect to precision, repeatability, and accuracy. All calibration curves showed good linearity (R(2) > 0.9994) within test ranges. The limit of detection and limit of quantification were lower than 0.01 and 0.03 μg/mL, respectively. The relative standard deviation for repeatability and the intermediate precision of six analytes were less than 1.6 and 2.5%, respectively, the overall recovery was 96.1-103.1%. In addition, fingerprint chromatography using hierarchical clustering analysis and similarity analysis was performed to differentiate and classify the samples. The method described here could provide a more comprehensive and reasonable scientific assessment of the quality of Rhizoma Chuanxiong. Therefore, the strategy is feasible, credible, and is easily and effectively adapted for evaluating the quality control of Rhizoma Chuanxiong. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Precise spatial control of cavitation erosion in a vessel phantom by using an ultrasonic standing wave.

PubMed

Shi, Aiwei; Huang, Peixuan; Guo, Shifang; Zhao, Lu; Jia, Yingjie; Zong, Yujin; Wan, Mingxi

2016-07-01

In atherosclerotic inducement in animal models, the conventionally used balloon injury is invasive, produces excessive vessel injuries at unpredictable locations and is inconvenient in arterioles. Fortunately, cavitation erosion, which plays an important role in therapeutic ultrasound in blood vessels, has the potential to induce atherosclerosis noninvasively at predictable sites. In this study, precise spatial control of cavitation erosion for superficial lesions in a vessel phantom was realised by using an ultrasonic standing wave (USW) with the participation of cavitation nuclei and medium-intensity ultrasound pulses. The superficial vessel erosions were restricted between adjacent pressure nodes, which were 0.87 mm apart in the USW field of 1 MHz. The erosion positions could be shifted along the vessel by nodal modulation under a submillimetre-scale accuracy without moving the ultrasound transducers. Moreover, the cavitation erosion of the proximal or distal wall could be determined by the types of cavitation nuclei and their corresponding cavitation pulses, i.e., phase-change microbubbles with cavitation pulses of 5 MHz and SonoVue microbubbles with cavitation pulses of 1 MHz. Effects of acoustic parameters of the cavitation pulses on the cavitation erosions were investigated. The flow conditions in the experiments were considered and discussed. Compared to only using travelling waves, the proposed method in this paper improves the controllability of the cavitation erosion and reduces the erosion depth, providing a more suitable approach for vessel endothelial injury while avoiding haemorrhage. Copyright © 2015 Elsevier B.V. All rights reserved.

Systems-oriented survey of noncontact temperature measurement techniques for rapid thermal processing

NASA Astrophysics Data System (ADS)

Peyton, David; Kinoshita, Hiroyuki; Lo, G. Q.; Kwong, Dim-Lee

1991-04-01

Rapid Thermal Processing (RTP) is becoming a popular approach for future ULSI manufacturing due to its unique low thermal budget and process flexibility. Furthermore when RTP is combined with Chemical Vapor Deposition (CVD) the so-called RTP-CVD technology it can be used to deposit ultrathin films with extremely sharp interfaces and excellent material qualities. One major consequence of this type of processing however is the need for extremely tight control of wafer temperature both to obtain reproducible results for process control and to minimize slip and warpage arising from nonuniformities in temperature. Specifically temperature measurement systems suitable for RiP must have both high precision--within 1-2 degrees--and a short response time--to output an accurate reading on the order of milliseconds for closedloop control. Any such in-situ measurement technique must be non-contact since thermocouples cannot meet the response time requirements and have problems with conductive heat flow in the wafer. To date optical pyrometry has been the most widely used technique for RiP systems although a number of other techniques are being considered and researched. This article examines several such techniques from a systems perspective: optical pyrometry both conventional and a new approach using ellipsometric techniques for concurrent emissivity measurement Raman scattering infrared laser thermometry optical diffraction thermometry and photoacoustic thermometry. Each approach is evaluated in terms of its actual or estimated manufacturing cost remote sensing capability precision repeatability dependence on processing history range

Improving probabilistic prediction of daily streamflow by identifying Pareto optimal approaches for modeling heteroscedastic residual errors

NASA Astrophysics Data System (ADS)

McInerney, David; Thyer, Mark; Kavetski, Dmitri; Lerat, Julien; Kuczera, George

2017-03-01

Reliable and precise probabilistic prediction of daily catchment-scale streamflow requires statistical characterization of residual errors of hydrological models. This study focuses on approaches for representing error heteroscedasticity with respect to simulated streamflow, i.e., the pattern of larger errors in higher streamflow predictions. We evaluate eight common residual error schemes, including standard and weighted least squares, the Box-Cox transformation (with fixed and calibrated power parameter λ) and the log-sinh transformation. Case studies include 17 perennial and 6 ephemeral catchments in Australia and the United States, and two lumped hydrological models. Performance is quantified using predictive reliability, precision, and volumetric bias metrics. We find the choice of heteroscedastic error modeling approach significantly impacts on predictive performance, though no single scheme simultaneously optimizes all performance metrics. The set of Pareto optimal schemes, reflecting performance trade-offs, comprises Box-Cox schemes with λ of 0.2 and 0.5, and the log scheme (λ = 0, perennial catchments only). These schemes significantly outperform even the average-performing remaining schemes (e.g., across ephemeral catchments, median precision tightens from 105% to 40% of observed streamflow, and median biases decrease from 25% to 4%). Theoretical interpretations of empirical results highlight the importance of capturing the skew/kurtosis of raw residuals and reproducing zero flows. Paradoxically, calibration of λ is often counterproductive: in perennial catchments, it tends to overfit low flows at the expense of abysmal precision in high flows. The log-sinh transformation is dominated by the simpler Pareto optimal schemes listed above. Recommendations for researchers and practitioners seeking robust residual error schemes for practical work are provided.

New horizons in local anesthesia.

PubMed

Lackey, A D

1998-08-01

The computer-controlled local anesthesia system and the TEA system present 21st-century alternatives to the traditional syringe. The TEA system is a non-invasive form of anesthesia that blocks pain electronically, using the same cellular mechanism as local chemical anesthesia. Targeted electronic anesthesia provides pain control for restorative dental procedures without the use of needles or postoperative discomfort, numbness, and swelling. The computer-assisted system outperforms syringes for traditional injections. This new system generates a precisely controlled anesthetic flow rate that eliminates the need for the operator to use thumb pressure to administer the injection. The lightweight pen-grasp handle results in greater tactile feedback, precision, operator ease, and patient comfort. The greatest advantage may be in the new techniques that it makes available. With these techniques, a dentist can target the teeth to achieve profound pulpal anesthesia, often without the annoying side effects of facial numbness. With this new advanced system in the maxillary arch, the AMSA injection offers clinical advantages over traditional anesthesia techniques, according to Dr. Mark Friedman, whom I consulted with earlier this year. In the mandibular arch, a safe and predictable PDL injection technique may replace the need for an inferior alveolar block in numerous clinical situations. The use of these modified injection techniques can have a positive influence on patient safety, patient comfort, and office productivity. Both of these systems take the fear and anxiety out of dental injections. They offer exciting advanced technology for local pain control. Significantly, if patient stress and anxiety are reduced, the operator immediately benefits. New horizons in local anesthesia offer improved opportunities for patient comfort using computer-controlled local anesthetic systems and TEA.

Biomimetic engineering of a generic cell-on-membrane architecture by microfluidic engraving for on-chip bioassays.

PubMed

Lee, Sang-Wook; Noh, Ji-Yoon; Park, Seung Chul; Chung, Jin-Ho; Lee, Byoungho; Lee, Sin-Doo

2012-05-22

We develop a biomimetic cell-on-membrane architecture in close-volume format which allows the interfacial biocompatibility and the reagent delivery capability for on-chip bioassays. The key concept lies in the microfluidic engraving of lipid membranes together with biological cells on a supported substrate with topographic patterns. The simultaneous engraving process of a different class of fluids is promoted by the front propagation of an air-water interface inside a flow-cell. This highly parallel, microfluidic cell-on-membrane approach opens a door to the natural biocompatibility in mimicking cellular stimuli-response behavior essential for diverse on-chip bioassays that can be precisely controlled in the spatial and temporal manner.

SAR operational aspects

NASA Astrophysics Data System (ADS)

Holmdahl, P. E.; Ellis, A. B. E.; Moeller-Olsen, P.; Ringgaard, J. P.

1981-12-01

The basic requirements of the SAR ground segment of ERS-1 are discussed. A system configuration for the real time data acquisition station and the processing and archive facility is depicted. The functions of a typical SAR processing unit (SPU) are specified, and inputs required for near real time and full precision, deferred time processing are described. Inputs and the processing required for provision of these inputs to the SPU are dealt with. Data flow through the systems, and normal and nonnormal operational sequence, are outlined. Prerequisites for maintaining overall performance are identified, emphasizing quality control. The most demanding tasks to be performed by the front end are defined in order to determine types of processors and peripherals which comply with throughput requirements.

Enumeration of residual white blood cells in leukoreduced blood products: Comparing flow cytometry with a portable microscopic cell counter.

PubMed

Castegnaro, Silvia; Dragone, Patrizia; Chieregato, Katia; Alghisi, Alberta; Rodeghiero, Francesco; Astori, Giuseppe

2016-04-01

Transfusion of blood components is potentially associated to the risk of cell-mediated adverse events and current guidelines require a reduction of residual white blood cells (rWBC) below 1 × 10(6) WBC/unit. The reference method to enumerate rare events is the flow cytometry (FCM). The ADAM-rWBC microscopic cell counter has been proposed as an alternative: it measures leukocytes after their staining with propidium iodide. We have tested the Adam-rWBC for the ability to enumerate rWBC in red blood cells and concentrates. We have validated the flow cytometry (FCM) for linearity, precision accuracy and robustness and then the ADAM-rWBC results have been compared with the FCM. Our data confirm the linearity, accuracy, precision and robustness of the FCM. The ADAM-rWBC has revealed an adequate precision and accuracy. Even if the Bland-Altman analysis of the paired data has indicated that the two systems are comparable, it should be noted that the rWBC values obtained by the ADAM-rWBC were significantly higher compared to FCM. In conclusion, the Adam-rWBC cell counter could represent an alternative where FCM technology expertise is not available, even if the risk that borderline products could be misclassified exists. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modeling and Positioning of a PZT Precision Drive System.

PubMed

Liu, Che; Guo, Yanling

2017-11-08

The fact that piezoelectric ceramic transducer (PZT) precision drive systems in 3D printing are faced with nonlinear problems with respect to positioning, such as hysteresis and creep, has had an extremely negative impact on the precision of laser focusing systems. To eliminate the impact of PZT nonlinearity during precision drive movement, mathematical modeling and theoretical analyses of each module comprising the system were carried out in this study, a micro-displacement measurement circuit based on Position Sensitive Detector (PSD) is constructed, followed by the establishment of system closed-loop control and creep control models. An XL-80 laser interferometer (Renishaw, Wotton-under-Edge, UK) was used to measure the performance of the precision drive system, showing that system modeling and control algorithms were correct, with the requirements for precision positioning of the drive system satisfied.

Modeling and Positioning of a PZT Precision Drive System

PubMed Central

Liu, Che; Guo, Yanling

2017-01-01

The fact that piezoelectric ceramic transducer (PZT) precision drive systems in 3D printing are faced with nonlinear problems with respect to positioning, such as hysteresis and creep, has had an extremely negative impact on the precision of laser focusing systems. To eliminate the impact of PZT nonlinearity during precision drive movement, mathematical modeling and theoretical analyses of each module comprising the system were carried out in this study, a micro-displacement measurement circuit based on Position Sensitive Detector (PSD) is constructed, followed by the establishment of system closed-loop control and creep control models. An XL-80 laser interferometer (Renishaw, Wotton-under-Edge, UK) was used to measure the performance of the precision drive system, showing that system modeling and control algorithms were correct, with the requirements for precision positioning of the drive system satisfied. PMID:29117140

Pulse mode readout techniques for use with non-gridded industrial ionization chambers

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

Popov, Vladimir E.; Degtiarenko, Pavel V.

2011-10-01

Highly sensitive readout technique for precision long-term radiation measurements has been developed and tested in the Radiation Control Department at Jefferson Lab. The new electronics design is used to retrieve ionization data in a pulse mode. The dedicated data acquisition system works with M=Audio Audiophile 192 High-Definition 24-bit/192 kHz audio cards, taking data in continuous waveform recording mode. The on-line data processing algorithms extract signals of the ionization events from the data flow and measure the ionization value for each event. Two different ion chambers are evaluated. The first is a Reuter-Stokes Argon-filled (at 25 atm) High Pressure Ionization Chambermore » (HPIC), commonly used as a detector part in many GE Reuter-Stokes instruments of the RSS series. The second is a VacuTec Model 70181, 5 atm Xenon-filled ionization chamber. Results for both chambers indicate that the techniques allow using industrial ICs for high sensitivity and precision long-term radiation measurements, while at the same time providing information about spectral characteristics of the radiation fields.« less

Epidermal devices for noninvasive, precise, and continuous mapping of macrovascular and microvascular blood flow

PubMed Central

Webb, R. Chad; Ma, Yinji; Krishnan, Siddharth; Li, Yuhang; Yoon, Stephen; Guo, Xiaogang; Feng, Xue; Shi, Yan; Seidel, Miles; Cho, Nam Heon; Kurniawan, Jonas; Ahad, James; Sheth, Niral; Kim, Joseph; Taylor VI, James G.; Darlington, Tom; Chang, Ken; Huang, Weizhong; Ayers, Joshua; Gruebele, Alexander; Pielak, Rafal M.; Slepian, Marvin J.; Huang, Yonggang; Gorbach, Alexander M.; Rogers, John A.

2015-01-01

Continuous monitoring of variations in blood flow is vital in assessing the status of microvascular and macrovascular beds for a wide range of clinical and research scenarios. Although a variety of techniques exist, most require complete immobilization of the subject, thereby limiting their utility to hospital or clinical settings. Those that can be rendered in wearable formats suffer from limited accuracy, motion artifacts, and other shortcomings that follow from an inability to achieve intimate, noninvasive mechanical linkage of sensors with the surface of the skin. We introduce an ultrathin, soft, skin-conforming sensor technology that offers advanced capabilities in continuous and precise blood flow mapping. Systematic work establishes a set of experimental procedures and theoretical models for quantitative measurements and guidelines in design and operation. Experimental studies on human subjects, including validation with measurements performed using state-of-the-art clinical techniques, demonstrate sensitive and accurate assessment of both macrovascular and microvascular flow under a range of physiological conditions. Refined operational modes eliminate long-term drifts and reduce power consumption, thereby providing steps toward the use of this technology for continuous monitoring during daily activities. PMID:26601309

Pressurized reactor system and a method of operating the same

DOEpatents

Isaksson, J.M.

1996-06-18

A method and apparatus are provided for operating a pressurized reactor system in order to precisely control the temperature within a pressure vessel in order to minimize condensation of corrosive materials from gases on the surfaces of the pressure vessel or contained circulating fluidized bed reactor, and to prevent the temperature of the components from reaching a detrimentally high level, while at the same time allowing quick heating of the pressure vessel interior volume during start-up. Super-atmospheric pressure gas is introduced from the first conduit into the fluidized bed reactor and heat derived reactions such as combustion and gasification are maintained in the reactor. Gas is exhausted from the reactor and pressure vessel through a second conduit. Gas is circulated from one part of the inside volume to another to control the temperature of the inside volume, such as by passing the gas through an exterior conduit which has a heat exchanger, control valve, blower and compressor associated therewith, or by causing natural convection flow of circulating gas within one or more generally vertically extending gas passages entirely within the pressure vessel (and containing heat exchangers, flow rate control valves, or the like therein). Preferably, inert gas is provided as a circulating gas, and the inert gas may also be used in emergency shut-down situations. In emergency shut-down reaction gas being supplied to the reactor is cut off, while inert gas from the interior gas volume of the pressure vessel is introduced into the reactor. 2 figs.

Pressurized reactor system and a method of operating the same

DOEpatents

Isaksson, Juhani M.

1996-01-01

A method and apparatus are provided for operating a pressurized reactor system in order to precisely control the temperature within a pressure vessel in order to minimize condensation of corrosive materials from gases on the surfaces of the pressure vessel or contained circulating fluidized bed reactor, and to prevent the temperature of the components from reaching a detrimentally high level, while at the same time allowing quick heating of the pressure vessel interior volume during start-up. Superatmospheric pressure gas is introduced from the first conduit into the fluidized bed reactor and heat derived reactions such as combustion and gassification are maintained in the reactor. Gas is exhausted from the reactor and pressure vessel through a second conduit. Gas is circulated from one part of the inside volume to another to control the temperature of the inside volume, such as by passing the gas through an exterior conduit which has a heat exchanger, control valve, blower and compressor associated therewith, or by causing natural convection flow of circulating gas within one or more generally vertically extending gas passages entirely within the pressure vessel (and containing heat exchangers, flow rate control valves, or the like therein). Preferably, inert gas is provided as a circulating gas, and the inert gas may also be used in emergency shut-down situations. In emergency shut-down reaction gas being supplied to the reactor is cut off, while inert gas from the interior gas volume of the pressure vessel is introduced into the reactor.

Evaluation of Flight Deck-Based Interval Management Crew Procedure Feasibility

NASA Technical Reports Server (NTRS)

Wilson, Sara R.; Murdoch, Jennifer L.; Hubbs, Clay E.; Swieringa, Kurt A.

2013-01-01

Air traffic demand is predicted to increase over the next 20 years, creating a need for new technologies and procedures to support this growth in a safe and efficient manner. The National Aeronautics and Space Administration's (NASA) Air Traffic Management Technology Demonstration - 1 (ATD-1) will operationally demonstrate the feasibility of efficient arrival operations combining ground-based and airborne NASA technologies. The integration of these technologies will increase throughput, reduce delay, conserve fuel, and minimize environmental impacts. The ground-based tools include Traffic Management Advisor with Terminal Metering for precise time-based scheduling and Controller Managed Spacing decision support tools for better managing aircraft delay with speed control. The core airborne technology in ATD-1 is Flight deck-based Interval Management (FIM). FIM tools provide pilots with speed commands calculated using information from Automatic Dependent Surveillance - Broadcast. The precise merging and spacing enabled by FIM avionics and flight crew procedures will reduce excess spacing buffers and result in higher terminal throughput. This paper describes a human-in-the-loop experiment designed to assess the acceptability and feasibility of the ATD-1 procedures used in a voice communications environment. This experiment utilized the ATD-1 integrated system of ground-based and airborne technologies. Pilot participants flew a high-fidelity fixed base simulator equipped with an airborne spacing algorithm and a FIM crew interface. Experiment scenarios involved multiple air traffic flows into the Dallas-Fort Worth Terminal Radar Control airspace. Results indicate that the proposed procedures were feasible for use by flight crews in a voice communications environment. The delivery accuracy at the achieve-by point was within +/- five seconds and the delivery precision was less than five seconds. Furthermore, FIM speed commands occurred at a rate of less than one per minute, and pilots found the frequency of the speed commands to be acceptable at all times throughout the experiment scenarios.

A programmable droplet-based microfluidic device applied to multiparameter analysis of single microbes and microbial communities

PubMed Central

Leung, Kaston; Zahn, Hans; Leaver, Timothy; Konwar, Kishori M.; Hanson, Niels W.; Pagé, Antoine P.; Lo, Chien-Chi; Chain, Patrick S.; Hallam, Steven J.; Hansen, Carl L.

2012-01-01

We present a programmable droplet-based microfluidic device that combines the reconfigurable flow-routing capabilities of integrated microvalve technology with the sample compartmentalization and dispersion-free transport that is inherent to droplets. The device allows for the execution of user-defined multistep reaction protocols in 95 individually addressable nanoliter-volume storage chambers by consecutively merging programmable sequences of picoliter-volume droplets containing reagents or cells. This functionality is enabled by “flow-controlled wetting,” a droplet docking and merging mechanism that exploits the physics of droplet flow through a channel to control the precise location of droplet wetting. The device also allows for automated cross-contamination-free recovery of reaction products from individual chambers into standard microfuge tubes for downstream analysis. The combined features of programmability, addressability, and selective recovery provide a general hardware platform that can be reprogrammed for multiple applications. We demonstrate this versatility by implementing multiple single-cell experiment types with this device: bacterial cell sorting and cultivation, taxonomic gene identification, and high-throughput single-cell whole genome amplification and sequencing using common laboratory strains. Finally, we apply the device to genome analysis of single cells and microbial consortia from diverse environmental samples including a marine enrichment culture, deep-sea sediments, and the human oral cavity. The resulting datasets capture genotypic properties of individual cells and illuminate known and potentially unique partnerships between microbial community members. PMID:22547789

Slow-Frequency Pulsed Transcranial Electrical Stimulation for Modulation of Cortical Plasticity Based on Reciprocity Targeting with Precision Electrical Head Modeling

PubMed Central

Luu, Phan; Essaki Arumugam, Easwara Moorthy; Anderson, Erik; Gunn, Amanda; Rech, Dennis; Turovets, Sergei; Tucker, Don M.

2016-01-01

In pain management as well as other clinical applications of neuromodulation, it is important to consider the timing parameters influencing activity-dependent plasticity, including pulsed versus sustained currents, as well as the spatial action of electrical currents as they polarize the complex convolutions of the cortical mantle. These factors are of course related; studying temporal factors is not possible when the spatial resolution of current delivery to the cortex is so uncertain to make it unclear whether excitability is increased or decreased with anodal vs. cathodal current flow. In the present study we attempted to improve the targeting of specific cortical locations by applying current through flexible source-sink configurations of 256 electrodes in a geodesic array. We constructed a precision electric head model for 12 healthy individuals. Extraction of the individual’s cortical surface allowed computation of the component of the induced current that is normal to the target cortical surface. In an effort to replicate the long-term depression (LTD) induced with pulsed protocols in invasive animal research and transcranial magnetic stimulation studies, we applied 100 ms pulses at 1.9 s intervals either in cortical-surface-anodal or cortical-surface-cathodal directions, with a placebo (sham) control. The results showed significant LTD of the motor evoked potential as a result of the cortical-surface-cathodal pulses in contrast to the placebo control, with a smaller but similar LTD effect for anodal pulses. The cathodal LTD after-effect was sustained over 90 min following current injection. These results support the feasibility of pulsed protocols with low total charge in non-invasive neuromodulation when the precision of targeting is improved with a dense electrode array and accurate head modeling. PMID:27531976

Automatic Stem Cell Detection in Microscopic Whole Mouse Cryo-imaging

PubMed Central

Wuttisarnwattana, Patiwet; Gargesha, Madhusudhana; Hof, Wouter van’t; Cooke, Kenneth R.

2016-01-01

With its single cell sensitivity over volumes as large as or larger than a mouse, cryo-imaging enables imaging of stem cell biodistribution, homing, engraftment, and molecular mechanisms. We developed and evaluated a highly automated software tool to detect fluorescently labeled stem cells within very large (~200GB) cryo-imaging datasets. Cell detection steps are: preprocess, remove immaterial regions, spatially filter to create features, identify candidate pixels, classify pixels using bagging decision trees, segment cell patches, and perform 3D labeling. There are options for analysis and visualization. To train the classifier, we created synthetic images by placing realistic digital cell models onto cryo-images of control mice devoid of cells. Very good cell detection results were (precision=98.49%, recall=99.97%) for synthetic cryo-images, (precision=97.81%, recall=97.71%) for manually evaluated, actual cryo-images, and <1% false positives in control mice. An α-multiplier applied to features allows one to correct for experimental variations in cell brightness due to labeling. On dim cells (37% of standard brightness), with correction, we improved recall (49.26%→99.36%) without a significant drop in precision (99.99%→99.75%). With tail vein injection, multipotent adult progenitor cells in a graft-versus-host-disease model in the first days post injection were predominantly found in lung, liver, spleen, and bone marrow. Distribution was not simply related to blood flow. The lung contained clusters of cells while other tissues contained single cells. Our methods provided stem cell distribution anywhere in mouse with single cell sensitivity. Methods should provide a rational means of evaluating dosing, delivery methods, cell enhancements, and mechanisms for therapeutic cells. PMID:26552080

Microfluidic device to control interstitial flow-mediated homotypic and heterotypic cellular communication.

PubMed

Alonzo, Luis F; Moya, Monica L; Shirure, Venktesh S; George, Steven C

2015-09-07

Tissue engineering can potentially recreate in vivo cellular microenvironments in vitro for an array of applications such as biological inquiry and drug discovery. However, the majority of current in vitro systems still neglect many biological, chemical, and mechanical cues that are known to impact cellular functions such as proliferation, migration, and differentiation. To address this gap, we have developed a novel microfluidic device that precisely controls the spatial and temporal interactions between adjacent three-dimensional cellular environments. The device consists of four interconnected microtissue compartments (~0.1 mm(3)) arranged in a square. The top and bottom pairs of compartments can be sequentially loaded with discrete cellularized hydrogels creating the opportunity to investigate homotypic (left to right or x-direction) and heterotypic (top to bottom or y-direction) cell-cell communication. A controlled hydrostatic pressure difference across the tissue compartments in both x and y direction induces interstitial flow and modulates communication via soluble factors. To validate the biological significance of this novel platform, we examined the role of stromal cells in the process of vasculogenesis. Our device confirms previous observations that soluble mediators derived from normal human lung fibroblasts (NHLFs) are necessary to form a vascular network derived from endothelial colony forming cell-derived endothelial cells (ECFC-ECs). We conclude that this platform could be used to study important physiological and pathological processes that rely on homotypic and heterotypic cell-cell communication.

Potentiometric flow injection system for determination of reductants using a polymeric membrane permanganate ion-selective electrode based on current-controlled reagent delivery.

PubMed

Song, Wenjing; Ding, Jiawang; Liang, Rongning; Qin, Wei

2011-10-17

A polymeric membrane permanganate-selective electrode has been developed as a current-controlled reagent release system for potentiometric detection of reductants in flow injection analysis. By applying an external current, diffusion of permanganate ions across the polymeric membrane can be controlled precisely. The permanganate ions released at the sample-membrane interface from the inner filling solution of the electrode are consumed by reaction with a reductant in the sample solution thus changing the measured membrane potential, by which the reductant can be sensed potentiometrically. Ascorbate, dopamine and norepinephrine have been employed as the model reductants. Under the optimized conditions, the potential peak heights are proportional to the reductant concentrations in the ranges of 1.0×10(-5) to 2.5×10(-7)M for ascorbate, of 1.0×10(-5) to 5.0×10(-7)M for dopamine, and of 1.0×10(-5) to 5.0×10(-7)M for norepinephrine, respectively with the corresponding detection limits of 7.8×10(-8), 1.0×10(-7) and 1.0×10(-7)M. The proposed system has been successfully applied to the determination of reductants in pharmaceutical preparations and vegetables, and the results agree well with those of iodimetric analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

Vascular endothelial function and oxidative stress mechanisms in patients with Behçet's syndrome.

PubMed

Chambers, J C; Haskard, D O; Kooner, J S

2001-02-01

We sought to test the hypothesis that vascular endothelial function is impaired in Behçet's syndrome and reflects increased levels of oxidative stress. Behçet's syndrome is a multisystem inflammatory disorder commonly complicated by vascular thrombosis and arterial aneurysm formation. The precise mechanisms underlying vascular disease in Behçet's syndrome are not known. We studied 19 patients with Behçet's syndrome (18 to 50 years old, 9 men) and 21 healthy volunteers (18 to 50 years old, 10 men). Brachial artery flow-mediated dilation (endothelium-dependent), and nitroglycerin (NTG)-induced dilation (endothelium-independent) were measured. To investigate oxidative stress mechanisms, vascular studies were repeated 1 h after administration of vitamin C (1 g, intravenous) in 12 patients and 12 control subjects. Flow-mediated dilation was reduced in patients with Behcet's syndrome as compared with control subjects (0.7 +/- 0.9% vs. 5.7 +/- 0.9%, p = 0.001). In contrast, there were no significant differences in the brachial artery diameter (4.2 +/- 0.2 vs. 4.0 +/- 0.2 mm, p = 0.47) or NTG-induced dilation (19.7 +/- 1.9% vs. 19.7 +/- 1.2%, p = 0.98). In regression analysis, Behçet's syndrome was associated with impaired flow-mediated dilation independent of age, gender, brachial artery diameter, blood pressure, cholesterol and glucose. Vitamin C increased flow-mediated dilation in Behçet's syndrome (0.2 +/- 0.7% to 3.5 +/- 1.0%, p = 0.002), but not in control subjects (4.3 +/- 0.6% to 4.7 +/- 0.4%, p = 0.51). In both groups, NTG-induced dilation and brachial artery diameter were unchanged after vitamin C treatment. Vascular endothelial function is impaired in Behcet's syndrome and can be rapidly improved by vitamin C treatment. Our results support a role for oxidative stress in the pathophysiology of Behçet's syndrome and provide a rationale for therapeutic studies aimed at reducing vascular complications in this disorder.

High Sensitive Precise 3D Accelerometer for Solar System Exploration with Unmanned Spacecrafts

NASA Astrophysics Data System (ADS)

Savenko, Y. V.; Demyanenko, P. O.; Zinkovskiy, Y. F.

Solutions of several space and geophysical tasks require creating high sensitive precise accelerometers with sensitivity in order of 10 -13 g. These several tasks are following: inertial navigation of the Earth and Space; gravimetry nearby the Earth and into Space; geology; geophysics; seismology etc. Accelerometers (gravimeters and gradientmeters) with required sensitivity are not available now. The best accelerometers in the world have sensitivity worth on 4-5 orders. It has been developed a new class of fiber-optical sensors (FOS) with light pulse modulation. These sensors have super high threshold sensitivity and wide (up to 10 orders) dynamic range, and can be used as a base for creating of measurement units of physical values as 3D superhigh sensitive precise accelerometers of linear accelerations that is suitable for highest requirements. The principle of operation of the FOS is organically combined with a digital signal processing. It allows decreasing hardware of the accelerometer due to using a usual air-borne or space-borne computer; correcting the influence of natural, design, technological drawbacks of FOS on measured results; neutralising the influence of extraordinary situations available during using of FOS; decreasing the influence of internal and external destabilising factors (as for FOS), such as oscillation of environment temperature, instability of pendulum cycle frequency of sensitive element of the accelerometer etc. We were conducted a quantitative estimation of precise opportunities of analogue FOS in structure of fiber optical measuring devices (FOMD) for elementary FOMD with analogue FOS built on modern element basis of fiber optics (FO), at following assumptions: absolute parameter stability of devices of FOS measuring path; single transmission band of registration path; maximum possible inserted in optical fiber (OF) a radiated power. Even at such idealized assumptions, a calculated value in limit reached minimum inaccuracy of measuring, by analogue FOS, has been ˜ 10-4 %. Substantially accessible values are yet worse on 2-3 order. The reason of poor precise performances of measurers on the basis of analogue FOS is metrologically poor quality of a stream of optical radiation carrying out role of the carrier and receptor of the information. It is a high level of photon noise and a small blanket intensity level. First reason reflects the fact of discreteness of flow of high-energy photons, and it is consequence of second one - smallness, on absolute value, of inserted power into OF from available radiation sources (RS). Works on improvement of FO elements are carrying out. Certainly, it will be created RS allow to insert enough of power into standard OF. But simple increasing of optical flow power in measuring path of FOS will not be able to decide radically the problem of increasing of measuring prices: with raising of power in proportion of square root of its value there is raising a power of photon noises - 1000-times increase of power promises only 30-times increase of measuring precise; insertion into OF more large power (˜ 1 W for standard silicon OF) causes an appearance of non-linear effects in it, which destroying an operating principle of analogue FOS. Thus, it is needed to constatate impossibility of building, at that time, measurers of analogue FOS, concurated with traditional (electrical) measurers on measuring precise. At that all, advantages of FO, as basis of building of FO MD requires to find ways for decision of these problems. Analysis of problem of sensitivity of usual (analogue) FOS has brought us to conclusion about necessity of reviewing of principles of information signal forming in FOS and principles its next electronic processing. For radical increasing of accuracy of measurements with using FOS it is necessary to refuse analogue modulation of optical flow and to transfer to discreet its modulations, entering thus in optical flow new, non-optical, parameters, which will serve as recipients of the information. It allows to save up all advantages of FOS (carrier of information, as earlier, remains an optical flow), but problem of accuracy of measurements now will not be more connected with problem of measurement of low power intensity of optical flow - it is transferred from area of optical measurements in other, non-optical area, where there is no this problem, or it had been solved duly. It had been developed a new class of FOS with pulse modulation of radiation flow intensity at the Department of Design and Production of Redioelectronic Systems of National Technical University of Ukraine ``Kiev Polytechnic Institute''. PFOS have benefit differ from usual analogue FOS on high threshold sensitivity and wide dynamic range of measured values. As example there are described design and performances of proposed 3D accelerometer. High precision of accelerometer measurements on PFOS is provided by following: possibility of high precision measurements of time intervals, which serve as informative parameters in output pulse signal of PFOS; possibility of creating a high quality quartz oscillating system, which serves as sensitive element of PFOS; insensitiveness of metrological performances of the accelerometer to any parameter instabilities (time, temperature, etc.) of optical and electrical elements in measuring path of PFOS; digital processing of PFOS signal practically excludes processing errors; principle insensitiveness of PFOS to electromagnetic noises of any nature and any intensity; possibility of direct correction of measuring results, during their processing, for taking into account and excluding undesirable influences of any destabilizing factors are acting on PFOS. Quasi stationary approach The developed 3D accelerometer on PFOS of extra low accelerations has unique technical performances, that confirms our conclusions about potentially high metrological abilities of pulse FOS. It has the following performances (calculated): threshold sensitivity is (10 -9 ldots 10 -13) g (threshold is determine by customer with determination of sizes of sensor and electronic processing unit); dynamic range is 10 7 ldots 10 9 ; frequency range is 0 ldots 10 Hz; mass is 50 grams; size: length is 120 mm and diameter is 20 mm In addition, that it can be used as accelerometer properly, on its base it is possible to create the strapdown inertial systems (SIS) for spacecraft. Flight control is carried out in accordance to flight programe of spacecraft without support connection with external reference objects. These SIS allow: - direct control over changes of orbital parameter or flight track, caused by action of extra low but long time external force factors (braking action of planet atmosphere remains, sun wind pressure, etc.) on spacecraft; - checking correction of orbital parameters (spacecraft track) by including of low power spaceborne engine; The developed accelerometer can be also used as high sensitive gravimeter for geophysical investigations and geological explorations - anywhere, where it is required to measure extra low deviation of terrestrial gravity value. High sensitivity of described accelerometers allows to create, on its base, gradientometers of real system for investigation of Planet gravity field heterogeneity from spacecraft orbit. This opens possibilities of practical solution of number important tasks of Planet physics.

Energy conserving numerical methods for the computation of complex vortical flows

NASA Astrophysics Data System (ADS)

Allaneau, Yves

One of the original goals of this thesis was to develop numerical tools to help with the design of micro air vehicles. Micro Air Vehicles (MAVs) are small flying devices of only a few inches in wing span. Some people consider that as their size becomes smaller and smaller, it would be increasingly more difficult to keep all the classical control surfaces such as the rudders, the ailerons and the usual propellers. Over the years, scientists took inspiration from nature. Birds, by flapping and deforming their wings, are capable of accurate attitude control and are able to generate propulsion. However, the biomimicry design has its own limitations and it is difficult to place a hummingbird in a wind tunnel to study precisely the motion of its wings. Our approach was to use numerical methods to tackle this challenging problem. In order to precisely evaluate the lift and drag generated by the wings, one needs to be able to capture with high fidelity the extremely complex vortical flow produced in the wake. This requires a numerical method that is stable yet not too dissipative, so that the vortices do not get diffused in an unphysical way. We solved this problem by developing a new Discontinuous Galerkin scheme that, in addition to conserving mass, momentum and total energy locally, also preserves kinetic energy globally. This property greatly improves the stability of the simulations, especially in the special case p=0 when the approximation polynomials are taken to be piecewise constant (we recover a finite volume scheme). In addition to needing an adequate numerical scheme, a high fidelity solution requires many degrees of freedom in the computations to represent the flow field. The size of the smallest eddies in the flow is given by the Kolmogoroff scale. Capturing these eddies requires a mesh counting in the order of Re³ cells, where Re is the Reynolds number of the flow. We show that under-resolving the system, to a certain extent, is acceptable. However our simulations still required meshes containing tens of millions of degrees of freedom. Such computations can only be done in reasonable amounts of time by spreading the work on multiple CPUs via domain decomposition. Further speed-up efforts were made by implementing a version of the code for GPUs using Nvidia's CUDA programming language. Finally we searched for optimal wing motions by coupling our computational fluid dynamics code with the optimization package SNOPT. The wing motion was parameterized by a few angles describing the local curvature and the twisting of the wing. These were expressed in terms of truncated Fourier series, the Fourier coefficients being our optimization parameters. With this approach we were able to obtain propulsive efficiencies of around 50% (thrust power/power input).

Precision Control of Multiple Quantum Cascade Lasers for Calibration Systems

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

Taubman, Matthew S.; Myers, Tanya L.; Pratt, Richard M.

We present a precision, digitally interfaced current controller for quantum cascade lasers, with demonstrated DC and modulated temperature coefficients of 1- 2 ppm/ºC and 15 ppm/ºC respectively. High linearity digital to analog converters (DACs) together with an ultra-precision voltage reference, produce highly stable, precision voltages. These are in turn selected by a low charge-injection multiplexer (MUX) chip, which are then used to set output currents via a linear current regulator. The controller is operated in conjunction with a power multiplexing unit, allowing one of three lasers to be driven by the controller while ensuring protection of controller and all lasersmore » during operation, standby and switching. Simple ASCII commands sent over a USB connection to a microprocessor located in the current controller operate both the controller (via the DACs and MUX chip) and the power multiplexer.« less

Fabrication of micro metallic valve and pump

NASA Astrophysics Data System (ADS)

Yang, Ming; Kabasawa, Yasunari; Ito, Kuniyoshi

2010-03-01

Fabrication of micro devices by using micro metal forming was proposed by the authors. We developed a desktop servo-press machine with precise tooling system. Precise press forming processes including micro forging and micro joining has been carried out in a progressive die. In this study, micro metallic valve and pump were fabricated by using the precise press forming. The components are made of sheet metals, and assembled in to a unit in the progressive die. A micro check-valve with a diameter of 3mm and a length of 3.2mm was fabricated, and the property of flow resistance was evaluated. The results show that the check valve has high property of leakage proof. Since the valve is a unit parts with dimensions of several millimeters, it has advantage to be adapted to various pump design. Here, two kinds of micro pumps with the check-valves were fabricated. One is diaphragm pump actuated by vibration of the diaphragm, and another is tube-shaped pump actuated by resonation. The flow quantities of the pumps were evaluated and the results show that both of the pumps have high pumping performance.

Conceptual-level workflow modeling of scientific experiments using NMR as a case study

PubMed Central

Verdi, Kacy K; Ellis, Heidi JC; Gryk, Michael R

2007-01-01

Background Scientific workflows improve the process of scientific experiments by making computations explicit, underscoring data flow, and emphasizing the participation of humans in the process when intuition and human reasoning are required. Workflows for experiments also highlight transitions among experimental phases, allowing intermediate results to be verified and supporting the proper handling of semantic mismatches and different file formats among the various tools used in the scientific process. Thus, scientific workflows are important for the modeling and subsequent capture of bioinformatics-related data. While much research has been conducted on the implementation of scientific workflows, the initial process of actually designing and generating the workflow at the conceptual level has received little consideration. Results We propose a structured process to capture scientific workflows at the conceptual level that allows workflows to be documented efficiently, results in concise models of the workflow and more-correct workflow implementations, and provides insight into the scientific process itself. The approach uses three modeling techniques to model the structural, data flow, and control flow aspects of the workflow. The domain of biomolecular structure determination using Nuclear Magnetic Resonance spectroscopy is used to demonstrate the process. Specifically, we show the application of the approach to capture the workflow for the process of conducting biomolecular analysis using Nuclear Magnetic Resonance (NMR) spectroscopy. Conclusion Using the approach, we were able to accurately document, in a short amount of time, numerous steps in the process of conducting an experiment using NMR spectroscopy. The resulting models are correct and precise, as outside validation of the models identified only minor omissions in the models. In addition, the models provide an accurate visual description of the control flow for conducting biomolecular analysis using NMR spectroscopy experiment. PMID:17263870

Conceptual-level workflow modeling of scientific experiments using NMR as a case study.

PubMed

Verdi, Kacy K; Ellis, Heidi Jc; Gryk, Michael R

2007-01-30

Scientific workflows improve the process of scientific experiments by making computations explicit, underscoring data flow, and emphasizing the participation of humans in the process when intuition and human reasoning are required. Workflows for experiments also highlight transitions among experimental phases, allowing intermediate results to be verified and supporting the proper handling of semantic mismatches and different file formats among the various tools used in the scientific process. Thus, scientific workflows are important for the modeling and subsequent capture of bioinformatics-related data. While much research has been conducted on the implementation of scientific workflows, the initial process of actually designing and generating the workflow at the conceptual level has received little consideration. We propose a structured process to capture scientific workflows at the conceptual level that allows workflows to be documented efficiently, results in concise models of the workflow and more-correct workflow implementations, and provides insight into the scientific process itself. The approach uses three modeling techniques to model the structural, data flow, and control flow aspects of the workflow. The domain of biomolecular structure determination using Nuclear Magnetic Resonance spectroscopy is used to demonstrate the process. Specifically, we show the application of the approach to capture the workflow for the process of conducting biomolecular analysis using Nuclear Magnetic Resonance (NMR) spectroscopy. Using the approach, we were able to accurately document, in a short amount of time, numerous steps in the process of conducting an experiment using NMR spectroscopy. The resulting models are correct and precise, as outside validation of the models identified only minor omissions in the models. In addition, the models provide an accurate visual description of the control flow for conducting biomolecular analysis using NMR spectroscopy experiment.

Characterization and Prediction of Flow Behavior in High-Manganese Twinning Induced Plasticity Steels: Part II. Jerky Flow and Instantaneous Strain Rate

NASA Astrophysics Data System (ADS)

Saeed-Akbari, A.; Mishra, A. K.; Mayer, J.; Bleck, W.

2012-05-01

The jerky and smooth flow curves in high-manganese twinning induced plasticity (TWIP) steels were investigated by comparing Fe-Mn-C and Fe-Mn-Al-C systems. The pronounced serrations on the flow curves of Fe-Mn-C TWIP steel, produced during tensile testing at 300 K (27 °C) and 373 K (100 °C), were shown to be the result of localized high-temperature Portevin Le-Chatelier (PLC) bands moving across the gage length throughout the deformation. The speed of the PLC bands and their temperature effects were found to be strongly dependent on the applied strain rate, which was controlled by adjusting the cross-head speed of the tensile testing machine. The localized temperature-dependent stacking fault energy (SFE) variations resulting from the PLC effect and adiabatic heating were analyzed and compared for both slow and fast deformation rates. The instabilities in the measured logarithmic strain values caused by jerky flow could cause the local strain rate to deviate systematically from the targeted (applied) strain rate. These instabilities are better observed by calculating the instantaneous strain rate (ISR) values for each instant of deformation along the entire gage length. Finally, a new type of diagram was developed by plotting the true stress against the ISR values. From the diagram, the onset of different mechanisms, such as deformation twinning, nonpronounced, and pronounced serrations, could be marked precisely.

The combustion program at CTR

NASA Technical Reports Server (NTRS)

Poinsot, Thierry J.

1993-01-01

Understanding and modeling of turbulent combustion are key problems in the computation of numerous practical systems. Because of the lack of analytical theories in this field and of the difficulty of performing precise experiments, direct numerical simulation (DNS) appears to be one of the most attractive tools to use in addressing this problem. The general objective of DNS of reacting flows is to improve our knowledge of turbulent combustion but also to use this information for turbulent combustion models. For the foreseeable future, numerical simulation of the full three-dimensional governing partial differential equations with variable density and transport properties as well as complex chemistry will remain intractable; thus, various levels of simplification will remain necessary. On one hand, the requirement to simplify is not necessarily a handicap: numerical simulations allow the researcher a degree of control in isolating specific physical phenomena that is inaccessible in experiments. CTR has pursued an intensive research program in the field of DNS for turbulent reacting flows since 1987. DNS of reacting flows is quite different from DNS of non-reacting flows: without reaction, the equations to solve are clearly the five conservation equations of the Navier Stokes system for compressible situations (four for incompressible cases), and the limitation of the approach is the Reynolds number (or in other words the number of points in the computation). For reacting flows, the choice of the equations, the species (each species will require one additional conservation equation), the chemical scheme, and the configuration itself is more complex.

2005 Precision Strike Technology Symposium

DTIC Science & Technology

2005-10-20

Radars in  Production  Mission Computer  Software   Functionality to drive Mission System Requirements  Liquid  Cooling   Expanded  Cooling   Capability and Flow...Targeting Demonstration Using the APL Precision Target Locator Demonstrator, Mr. Ben Huguenin and Mr. Joe Schissler, Johns Hopkins University, Applied ...Forces October 18-20, 2005 Kossiakoff Conference Center The Johns Hopkins University/ Applied Physics Laboratory, Laurel, MD David K. Sanders

The use of pneumatically generated water pressure signals for aquifer characterization

NASA Astrophysics Data System (ADS)

Fort, M.; Roberts, R.; Chace, D.

2013-12-01

The use of pneumatically generated pressure signals for aquifer characterization Hydraulic tests are the most reliable method of obtaining estimates of hydrologic properties, such as conductivity, that are essential for flow and transport modeling. The use of a sinusoidal signal for hydraulic testing is well established, with Streltsova (1988), Rasmussen (2003) and others having developed analytic solutions. Sinusoidal tests provide a unique easily distinguished signal that reduces ambiguity during analysis and we show that a sinusoidal pressure signal propagates farther into the formation than a standard slug-test signal. If a sinusoidal test is combined with a slug and/or a constant rate test, it can further reduce uncertainty in the estimated parameter values. We demonstrate how pneumatic pressure can be used to generate all three of these signals. By positioning pressure transducers both below the water level and in the head space above the water, we can monitor the total pressure acting on the formation and the changes in water level. From the changes in water level, it is possible to calculate the flow rate in and out of the well, assuming that the well diameter and water density are known. Using gas flow controllers with a Supervisory Control And Data Acquisition (SCADA) system we are able to precisely control the pressures in the well. The use of pneumatic pressure has the advantage that it requires less equipment (no pumps) and produces no water. We also show how the numerical well test analysis program nSIGHTS can be used to analyze all three types of tests simultaneously and to assess the relative contribution of each type of test to the parameter estimation. nSIGHTS was recently released as open source by Sandia National Laboratories and is available for free.

Design and control of rotating soil-like substrate plant-growing facility based on plant water requirement and computational fluid dynamics simulation

NASA Astrophysics Data System (ADS)

Hu, Dawei; Li, Leyuan; Liu, Hui; Zhang, Houkai; Fu, Yuming; Sun, Yi; Li, Liang

It is necessary to process inedible plant biomass into soil-like substrate (SLS) by bio-compost to realize biological resource sustainable utilization. Although similar to natural soil in structure and function, SLS often has uneven water distribution adversely affecting the plant growth due to unsatisfactory porosity, permeability and gravity distribution. In this article, SLS plant-growing facility (SLS-PGF) were therefore rotated properly for cultivating lettuce, and the Brinkman equations coupled with laminar flow equations were taken as governing equations, and boundary conditions were specified by actual operating characteristics of rotating SLS-PGF. Optimal open-control law of the angular and inflow velocity was determined by lettuce water requirement and CFD simulations. The experimental result clearly showed that water content was more uniformly distributed in SLS under the action of centrifugal and Coriolis force, rotating SLS-PGF with the optimal open-control law could meet lettuce water requirement at every growth stage and achieve precise irrigation.

A three-dimensional bioprinting system for use with a hydrogel-based biomaterial and printing parameter characterization.

PubMed

Song, Seung-Joon; Choi, Jaesoon; Park, Yong-Doo; Lee, Jung-Joo; Hong, So Young; Sun, Kyung

2010-11-01

Bioprinting is an emerging technology for constructing tissue or bioartificial organs with complex three-dimensional (3D) structures. It provides high-precision spatial shape forming ability on a larger scale than conventional tissue engineering methods, and simultaneous multiple components composition ability. Bioprinting utilizes a computer-controlled 3D printer mechanism for 3D biological structure construction. To implement minimal pattern width in a hydrogel-based bioprinting system, a study on printing characteristics was performed by varying printer control parameters. The experimental results showed that printing pattern width depends on associated printer control parameters such as printing flow rate, nozzle diameter, and nozzle velocity. The system under development showed acceptable feasibility of potential use for accurate printing pattern implementation in tissue engineering applications and is another example of novel techniques for regenerative medicine based on computer-aided biofabrication system. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Microplastic bases for constitutive characterization of aluminum alloys and their correlation to sheet formability

NASA Astrophysics Data System (ADS)

Diak, Bradley James

Forming limit predictions that incorporate crystal plasticity models still cannot adequately predict the deformation performance of polycrystalline materials. The reason for the limitation in predictive power is that the constitutive equations used to connect to the atomic scale assume an affine deformation which do not have a physical basis, but give general trends. This study was undertaken to better elucidate the microplastic process and how it manifests itself phenomenologically. In this endeavour, the strain rate sensitivity of the flow stress was identified as one parameter that greatly affects the forming limit. Hence, an attempt was made to properly define and measure the strain rate sensitivity according to the dictates of thermodynamics. The thermodynamics of systems can delineate the evolution of the state of a material if the state variables can be characterized and measured. Inevitably, these variables must be determined at constant structure. Using the theory of thermally activated flow, where the movement of dislocations past obstacles is the rate controlling step, the mechanical testing techniques have been designed to statistically assess the dynamic evolution of the microstructure by controlling the temperature, T, and strain rate, dotvarepsilon, and measuring the stress, sigma, mean slip distance, lambda, and mean slip velocity, dotlambda, to define sigma=f(lambda,dotlambda, T). The apparent activation volume, which characterizes the obstacle resistance of strain centres, is determined at constant structure by applying the strain rate change technique. Strain rate sensitivity data are compared to the Cottrell-Stokes relation, and the Haasen plot is used to separate the different contributions to the flow stress. Using these precise measurements at interrupted segments of strain, the evolution of a microstructure during plastic flow can be monitored. By this examination of different rate controlling obstacles, the microstructural parameters which correlate to formability were assessed. Detailed experimental evidence is given for different aluminum alloys containing mainly fast or slow diffusing solute species, transition precipitates, dispersed particles, and/or dislocation debris. These systems of Al-Fe, Al-Cr, Al-Cu, Al-Mg, and Al-Mg-Si, all displayed unique dislocation-defect interactions which could be elucidated by the current theory of thermally activated flow.

Neural control and precision of flight muscle activation in Drosophila.

PubMed

Lehmann, Fritz-Olaf; Bartussek, Jan

2017-01-01

Precision of motor commands is highly relevant in a large context of various locomotor behaviors, including stabilization of body posture, heading control and directed escape responses. While posture stability and heading control in walking and swimming animals benefit from high friction via ground reaction forces and elevated viscosity of water, respectively, flying animals have to cope with comparatively little aerodynamic friction on body and wings. Although low frictional damping in flight is the key to the extraordinary aerial performance and agility of flying birds, bats and insects, it challenges these animals with extraordinary demands on sensory integration and motor precision. Our review focuses on the dynamic precision with which Drosophila activates its flight muscular system during maneuvering flight, considering relevant studies on neural and muscular mechanisms of thoracic propulsion. In particular, we tackle the precision with which flies adjust power output of asynchronous power muscles and synchronous flight control muscles by monitoring muscle calcium and spike timing within the stroke cycle. A substantial proportion of the review is engaged in the significance of visual and proprioceptive feedback loops for wing motion control including sensory integration at the cellular level. We highlight that sensory feedback is the basis for precise heading control and body stability in flies.

Development and Operation of an Automatic Rotor Trim Control System for use During the UH-60 Individual Blade Control Wind Tunnel Test

NASA Technical Reports Server (NTRS)

Theodore, Colin R.

2010-01-01

A full-scale wind tunnel test to evaluate the effects of Individual Blade Control (IBC) on the performance, vibration, noise and loads of a UH-60A rotor was recently completed in the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel [1]. A key component of this wind tunnel test was an automatic rotor trim control system that allowed the rotor trim state to be set more precisely, quickly and repeatably than was possible with the rotor operator setting the trim condition manually. The trim control system was also able to maintain the desired trim condition through changes in IBC actuation both in open- and closed-loop IBC modes, and through long-period transients in wind tunnel flow. This ability of the trim control system to automatically set and maintain a steady rotor trim enabled the effects of different IBC inputs to be compared at common trim conditions and to perform these tests quickly without requiring the rotor operator to re-trim the rotor. The trim control system described in this paper was developed specifically for use during the IBC wind tunnel test

Hydrological heterogeneity in agricultural riparian buffer strips

NASA Astrophysics Data System (ADS)

Hénault-Ethier, Louise; Larocque, Marie; Perron, Rachel; Wiseman, Natalie; Labrecque, Michel

2017-03-01

Riparian buffer strips (RBS) may protect surface water and groundwater in agricultural settings, although their effectiveness, observed in field-scale studies, may not extend to a watershed scale. Hydrologically-controlled leaching plots have often shown RBS to be effective at buffering nutrients and pesticides, but uncontrolled field studies have sometimes suggested limited effectiveness. The limited RBS effectiveness may be explained by the spatiotemporal hydrological heterogeneity near non-irrigated fields. This hypothesis was tested in conventional corn and soy fields in the St. Lawrence Lowlands of southern Quebec (Canada), where spring melt brings heavy and rapid runoff, while summer months are hot and dry. One field with a mineral soil (Saint-Roch-de-l'Achigan) and another with an organic-rich soil (Boisbriand) were equipped with passive runoff collectors, suction cup lysimeters, and piezometers placed before and after a 3 m-wide RBS, and monitored from 2011 to 2014. Soil topography of the RBS was mapped to a 1 cm vertical precision and a 50 cm sampling grid. On average, surface runoff intersects the RBS perpendicularly, but is subject to substantial local heterogeneity. Groundwater saturates the root zones, but flows little at the time of snowmelt. Groundwater flow is not consistently perpendicular to the RBS, and may reverse, flowing from stream to field under low water flow regimes with stream-aquifer connectivity, thus affecting RBS effectiveness calculations. Groundwater flow direction can be influenced by stratigraphy, local soil hydraulic properties, and historical modification of the agricultural stream beds. Understanding the spatiotemporal heterogeneity of surface and groundwater flows is essential to correctly assess the effectiveness of RBS in intercepting agro-chemical pollution. The implicit assumption that water flows across vegetated RBS, from the field to the stream, should always be verified.

Objective definition of rainfall intensity-duration thresholds for the initiation of post-fire debris flows in southern California

USGS Publications Warehouse

Staley, Dennis; Kean, Jason W.; Cannon, Susan H.; Schmidt, Kevin M.; Laber, Jayme L.

2012-01-01

Rainfall intensity–duration (ID) thresholds are commonly used to predict the temporal occurrence of debris flows and shallow landslides. Typically, thresholds are subjectively defined as the upper limit of peak rainstorm intensities that do not produce debris flows and landslides, or as the lower limit of peak rainstorm intensities that initiate debris flows and landslides. In addition, peak rainstorm intensities are often used to define thresholds, as data regarding the precise timing of debris flows and associated rainfall intensities are usually not available, and rainfall characteristics are often estimated from distant gauging locations. Here, we attempt to improve the performance of existing threshold-based predictions of post-fire debris-flow occurrence by utilizing data on the precise timing of debris flows relative to rainfall intensity, and develop an objective method to define the threshold intensities. We objectively defined the thresholds by maximizing the number of correct predictions of debris flow occurrence while minimizing the rate of both Type I (false positive) and Type II (false negative) errors. We identified that (1) there were statistically significant differences between peak storm and triggering intensities, (2) the objectively defined threshold model presents a better balance between predictive success, false alarms and failed alarms than previous subjectively defined thresholds, (3) thresholds based on measurements of rainfall intensity over shorter duration (≤60 min) are better predictors of post-fire debris-flow initiation than longer duration thresholds, and (4) the objectively defined thresholds were exceeded prior to the recorded time of debris flow at frequencies similar to or better than subjective thresholds. Our findings highlight the need to better constrain the timing and processes of initiation of landslides and debris flows for future threshold studies. In addition, the methods used to define rainfall thresholds in this study represent a computationally simple means of deriving critical values for other studies of nonlinear phenomena characterized by thresholds.

Monitoring of well-controlled turbidity currents using the latest technology and a dredger

NASA Astrophysics Data System (ADS)

Vellinga, A. J.; Cartigny, M.; Clare, M. A.; Mastbergen, D. R.; Van den Ham, G.; Koelewijn, A. R.; de Kleine, M.; Hizzett, J. L.; Azpiroz, M.; Simmons, S.; Parsons, D. R.

2017-12-01

Recent advances in technology enable monitoring of turbidity currents at field scale. This now allows us to test models developed at small-scale in the laboratory. However, interpretation of field measurements is complicated, as the instruments used are not bespoke for monitoring turbidity currents. For example, Acoustic Doppler Current Profiles (ADCPs) are developed to measure clear water flows, and 3D multimode multibeam echosounders (M3s) are made to find shoals of fish. Calibration of field-scale measurements is complicated, as we often do not know fundamental information about the measured flows, such as grain size and initial sediment volume. We present field-scale measurements of two turbidity currents for which the pre- and post-flow bathymetry, grain size and initial sediment volume is known precisely. A dredger created two turbidity currents by twice discharging 500m3 of sediment on a slope in the Western Scheldt Estuary, the Netherlands. Flow velocity and echo intensity were directly measured using three frequencies of ADCPs, and two M3 sonars imaged the flow morphology in 3D. This experiment was part of the IJkdijk research program. The turbidity currents formed upstream-migrating crescentic shaped bedforms. The ADCPs measured peak flow velocities of 1-1.5 m/s. The M3s however suggest head velocities are 2-4 m/s. The two measured turbidity currents have thicknesses of about 3m, are up to 50m in width and travel downslope for about 150m. Flow dimensions, duration, and sediment discharge indicate a mean sediment concentration of 1-5 vol. %. Flow morphology evolves from a fast but thin, snout-like head, to a thicker body, and a dilute tail. The initial flow dynamics contrast with many laboratory experiments, but are coherent with direct measurements of much larger flows in the Congo Canyon. Well-constrained field studies, like this one, thus help to understand the validity of scaling from the laboratory to the deep sea.

Frugal Droplet Microfluidics Using Consumer Opto-Electronics.

PubMed

Frot, Caroline; Taccoen, Nicolas; Baroud, Charles N

2016-01-01

The maker movement has shown how off-the-shelf devices can be combined to perform operations that, until recently, required expensive specialized equipment. Applying this philosophy to microfluidic devices can play a fundamental role in disseminating these technologies outside specialist labs and into industrial use. Here we show how nanoliter droplets can be manipulated using a commercial DVD writer, interfaced with an Arduino electronic controller. We couple the optical setup with a droplet generation and manipulation device based on the "confinement gradients" approach. This device uses regions of different depths to generate and transport the droplets, which further simplifies the operation and reduces the need for precise flow control. The use of robust consumer electronics, combined with open source hardware, leads to a great reduction in the price of the device, as well as its footprint, without reducing its performance compared with the laboratory setup.

OSIRIS-REx Contamination Control Strategy and Implementation

NASA Technical Reports Server (NTRS)

Dworkin, J. P.; Adelman, L. A.; Ajluni, T.; Andronikov, A. V.; Aponte, J. C.; Bartels, A. E.; Beshore, E.; Bierhaus, E. B.; Brucato, J. R.; Bryan, B. H.;

Bioinspired optical sensors for unmanned aerial systems

NASA Astrophysics Data System (ADS)

Chahl, Javaan; Rosser, Kent; Mizutani, Akiko

2011-04-01

Insects are dependant on the spatial, spectral and temporal distributions of light in the environment for flight control and navigation. This paper reports on flight trials of implementations of insect inspired behaviors on unmanned aerial vehicles. Optical flow methods for maintaining a constant height above ground and a constant course have been demonstrated to provide navigation capabilities that are impossible using conventional avionics sensors. Precision control of height above ground and ground course were achieved over long distances. Other vision based techniques demonstrated include a biomimetic stabilization sensor that uses the ultraviolet and green bands of the spectrum, and a sky polarization compass. Both of these sensors were tested over long trajectories in different directions, in each case showing performance similar to low cost inertial heading and attitude systems. The behaviors demonstrate some of the core functionality found in the lower levels of the sensorimotor system of flying insects and shows promise for more integrated solutions in the future.

OSIRIS-REx Contamination Control Strategy and Implementation

NASA Astrophysics Data System (ADS)

Dworkin, J. P.; Adelman, L. A.; Ajluni, T.; Andronikov, A. V.; Aponte, J. C.; Bartels, A. E.; Beshore, E.; Bierhaus, E. B.; Brucato, J. R.; Bryan, B. H.; Burton, A. S.; Callahan, M. P.; Castro-Wallace, S. L.; Clark, B. C.; Clemett, S. J.; Connolly, H. C.; Cutlip, W. E.; Daly, S. M.; Elliott, V. E.; Elsila, J. E.; Enos, H. L.; Everett, D. F.; Franchi, I. A.; Glavin, D. P.; Graham, H. V.; Hendershot, J. E.; Harris, J. W.; Hill, S. L.; Hildebrand, A. R.; Jayne, G. O.; Jenkens, R. W.; Johnson, K. S.; Kirsch, J. S.; Lauretta, D. S.; Lewis, A. S.; Loiacono, J. J.; Lorentson, C. C.; Marshall, J. R.; Martin, M. G.; Matthias, L. L.; McLain, H. L.; Messenger, S. R.; Mink, R. G.; Moore, J. L.; Nakamura-Messenger, K.; Nuth, J. A.; Owens, C. V.; Parish, C. L.; Perkins, B. D.; Pryzby, M. S.; Reigle, C. A.; Righter, K.; Rizk, B.; Russell, J. F.; Sandford, S. A.; Schepis, J. P.; Songer, J.; Sovinski, M. F.; Stahl, S. E.; Thomas-Keprta, K.; Vellinga, J. M.; Walker, M. S.

2018-02-01

OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and <180 ng/cm2 of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.

Probing the shear viscosity of an active nematic film

NASA Astrophysics Data System (ADS)

Guillamat, Pau; Ignés-Mullol, Jordi; Shankar, Suraj; Marchetti, M. Cristina; Sagués, Francesc

2016-12-01

In vitro reconstituted active systems, such as the adenosine triphosphate (ATP)-driven microtubule bundle suspension developed by the Dogic group [T. Sanchez, D. T. Chen, S. J. DeCamp, M. Heymann, and Z. Dogic, Nature (London) 491, 431 (2012), 10.1038/nature11591], provide a fertile testing ground for elucidating the phenomenology of active liquid crystalline states. Controlling such novel phases of matter crucially depends on our knowledge of their material and physical properties. In this Rapid Communication, we show that the shear viscosity of an active nematic film can be probed by varying its hydrodynamic coupling to a bounding oil layer. Using the motion of disclinations as intrinsic tracers of the flow field and a hydrodynamic model, we obtain an estimate for the shear viscosity of the nematic film. Knowing this now provides us with an additional handle for robust and precision tunable control of the emergent dynamics of active fluids.

Electrical characteristics of silicon nanowire CMOS inverters under illumination.

PubMed

Yoo, Jeuk; Kim, Yoonjoong; Lim, Doohyeok; Kim, Sangsig

2018-02-05

In this study, we examine the electrical characteristics of complementary metal-oxide-semiconductor (CMOS) inverters with silicon nanowire (SiNW) channels on transparent substrates under illumination. The electrical characteristics vary with the wavelength and power of light due to the variation in the generation rates of the electric-hole pairs. Compared to conventional optoelectronic devices that sense the on/off states by the variation in the current, our device achieves the sensing of the on/off states with more precision by using the voltage variation induced by the wavelength or intensity of light. The device was fabricated on transparent substrates to maximize the light absorption using conventional CMOS technologies. The key difference between our SiNW CMOS inverters and conventional optoelectronic devices is the ability to control the flow of charge carriers more effectively. The improved sensitivity accomplished with the use of SiNW CMOS inverters allows better control of the on/off states.

OSIRIS-REx Contamination Control Strategy and Implementation

NASA Technical Reports Server (NTRS)

Dworkin, J. P.; Adelman, L. A.; Ajluni, T. M.; Andronikov, A. V.; Aponte, J. S.; Bartels, A. E.; Beshore, E.; Bierhaus, E. B.; Brucato, J. R.; Bryan, B. H.;

Frugal Droplet Microfluidics Using Consumer Opto-Electronics

PubMed Central

Frot, Caroline; Taccoen, Nicolas; Baroud, Charles N.

2016-01-01

The maker movement has shown how off-the-shelf devices can be combined to perform operations that, until recently, required expensive specialized equipment. Applying this philosophy to microfluidic devices can play a fundamental role in disseminating these technologies outside specialist labs and into industrial use. Here we show how nanoliter droplets can be manipulated using a commercial DVD writer, interfaced with an Arduino electronic controller. We couple the optical setup with a droplet generation and manipulation device based on the “confinement gradients” approach. This device uses regions of different depths to generate and transport the droplets, which further simplifies the operation and reduces the need for precise flow control. The use of robust consumer electronics, combined with open source hardware, leads to a great reduction in the price of the device, as well as its footprint, without reducing its performance compared with the laboratory setup. PMID:27560139

Bosch CO2 Reduction System Development

NASA Technical Reports Server (NTRS)

Holmes, R. F.; King, C. D.; Keller, E. E.

1975-01-01

Refinements in the design of a Bosch CO2 reduction unit for spacecraft O2 production are described. Sealing of the vacuum insulation jacket was simplified so that high vacuum and high insulation performance are easily maintained. The device includes a relatively simple concentric shell recuperative heat exchanger which operates at approximately 95% temperature effectiveness and helps lower power consumption. The influence of reactor temperature, pressure, and recycle gas composition on power consumption was investigated. In general, precise control is not required since power consumption is not very sensitive to moderate variations of these parameters near their optimum values. There are two process rate control modes which match flow rate to process demand. Catalyst conditioning, support, and packing pattern developments assure consistent starts, reduced energy consumption, and extended cartridge life. Operation levels for four or five men were maintained with overall power input values of 50 to 60 watts per man.

Super-resolved calibration-free flow cytometric characterization of platelets and cell-derived microparticles in platelet-rich plasma.

PubMed

Konokhova, Anastasiya I; Chernova, Darya N; Moskalensky, Alexander E; Strokotov, Dmitry I; Yurkin, Maxim A; Chernyshev, Andrei V; Maltsev, Valeri P

2016-02-01

Importance of microparticles (MPs), also regarded as extracellular vesicles, in many physiological processes and clinical conditions motivates one to use the most informative and precise methods for their characterization. Methods based on individual particle analysis provide statistically reliable distributions of MP population over characteristics. Although flow cytometry is one of the most powerful technologies of this type, the standard forward-versus-side-scattering plots of MPs and platelets (PLTs) overlap considerably because of similarity of their morphological characteristics. Moreover, ordinary flow cytometry is not capable of measurement of size and refractive index (RI) of MPs. In this study, we 1) employed the potential of the scanning flow cytometer (SFC) for identification and characterization of MPs from light scattering; 2) suggested the reference method to characterize MP morphology (size and RI) with high precision; and 3) determined the lowest size of a MP that can be characterized from light scattering with the SFC. We equipped the SFC with 405 and 488 nm lasers to measure the light-scattering profiles and side scattering from MPs, respectively. The developed two-stage method allowed accurate separation of PLTs and MPs in platelet-rich plasma. We used two optical models for MPs, a sphere and a bisphere, in the solution of the inverse light-scattering problem. This solution provides unprecedented precision in determination of size and RI of individual spherical MPs-median uncertainties (standard deviations) were 6 nm and 0.003, respectively. The developed method provides instrument-independent quantitative information on MPs, which can be used in studies of various factors affecting MP population. © 2015 International Society for Advancement of Cytometry.

A new spatially scanning 2.7 µm laser hygrometer and new small-scale wind tunnel for direct analysis of the H2O boundary layer structure at single plant leaves

NASA Astrophysics Data System (ADS)

Wunderle, K.; Rascher, U.; Pieruschka, R.; Schurr, U.; Ebert, V.

2015-01-01

A new spatially scanning TDLAS in situ hygrometer based on a 2.7-µm DFB diode laser was constructed and used to analyse the water vapour concentration boundary layer structure at the surface of a single plant leaf. Using an absorption length of only 5.4 cm, the TDLAS hygrometer permits a H2O vapour concentration resolution of 31 ppmv. This corresponds to a normalized precision of 1.7 ppm m. In order to preserve and control the H2O boundary layer on an individual leaf and to study the boundary layer dependence on the wind speed to which the leaf might be exposed in nature, we also constructed a new, application specific, small-scale, wind tunnel for individual plant leaves. The rectangular, closed-loop tunnel has overall dimensions of 1.2 × 0.6 m and a measurement chamber dimension of 40 × 54 mm (H × W). It allows to generate a laminar flow with a precisely controlled wind speed at the plant leaf surface. Combining honeycombs and a miniaturized compression orifice, we could generate and control stable wind speeds from 0.1 to 0.9 m/s, and a highly laminar and homogeneous flow with an excellent relative spatial homogeneity of 0.969 ± 0.03. Combining the spectrometer and the wind tunnel, we analysed (for the first time) non-invasively the wind speed-dependent vertical structure of the H2O vapour distribution within the boundary layer of a single plant leaf. Using our time-lag-free data acquisition procedure for phase locked signal averaging, we achieved a temporal resolution of 0.2 s for an individual spatial point, while a complete vertical spatial scan at a spatial resolution of 0.18 mm took 77 s. The boundary layer thickness was found to decrease from 6.7 to 3.6 mm at increasing wind speeds of 0.1-0.9 m/s. According to our knowledge, this is the first experimental quantification of wind speed-dependent H2O vapour boundary layer concentration profiles of single plant leaves.

Modified pressure loss model for T-junctions of engine exhaust manifold

NASA Astrophysics Data System (ADS)

Wang, Wenhui; Lu, Xiaolu; Cui, Yi; Deng, Kangyao

2014-11-01

The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.

Numerical modeling of multidimensional flow in seals and bearings used in rotating machinery

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Tam, L. T.; Przekwas, A.; Muszynska, A.; Braun, M. J.; Mullen, R. L.

1988-01-01

The rotordynamic behavior of turbomachinery is critically dependent on fluid dynamic rotor forces developed by various types of seals and bearings. The occurrence of self-excited vibrations often depends on the rotor speed and load. Misalignment and rotor wobbling motion associated with differential clearance were often attributed to stability problems. In general, the rotative character of the flowfield is a complex three dimensional system with secondary flow patterns that significantly alter the average fluid circumferential velocity. A multidimensional, nonorthogonal, body-fitted-grid fluid flow model is presented that describes the fluid dynamic forces and the secondary flow pattern development in seals and bearings. Several numerical experiments were carried out to demonstrate the characteristics of this complex flowfield. Analyses were performed by solving a conservation form of the three dimensional Navier-Stokes equations transformed to those for a rotating observer and using the general-purpose computer code PHOENICS with the assumptions that the rotor orbit is circular and that static eccentricity is zero. These assumptions have enabled a precise steady-state analysis to be used. Fluid injection from ports near the seal or bearing center increased fluid-film direct dynamic stiffness and, in some cases, significantly increased quadrature dynamic stiffness. Injection angle and velocity could be used for active rotordynamic control; for example, injection, when compared with no injection, increased direct dynamic stiffness, which is an important factor for hydrostatic bearings.

Flow and free running speed characterization of dental air turbine handpieces.

PubMed

Dyson, J E; Darvell, B W

1999-09-01

Dental air turbine handpieces have been widely used in clinical dentistry for over 30 years, yet little work has been reported on their performance. A few studies have been concerned with measurement of speed (i.e. rotation rate), torque and power performance of these devices, but neither investigations of functional relationships between controlling variables nor theory dealing specifically with this class of turbine have been reported. This has hindered the development of satisfactory methods of handpiece specification and of testing dental rotary cutting tools. It was the intention of the present work to remedy that deficiency. Measurements of pressure, temperature, gas flow rate and rotation rate were made with improved accuracy and precision for 14 ball bearing turbine handpieces on several gases. Functional relationships between gas properties, supply pressure, flow rate, turbine design factors and free running speed were identified and equations describing these aspects of behaviour of this class of turbine developed. The rotor radius, through peripheral Mach number, was found to be a major determinant of speed performance. In addition, gas flow was found to be an important limiting factor through the effect of choke. Each dental handpiece can be treated as a simple orifice of a characteristic cross-sectional area. Free running speed can be explained in terms of gas properties and pressure, with allowance for a design-specific performance coefficient.

Hybrid soft-lithography/laser machined microchips for the parallel generation of droplets†

PubMed Central

Muluneh, M.

2015-01-01

Microfluidic chips have been developed to generate droplets and microparticles with control over size, shape, and composition not possible using conventional methods. However, it has remained a challenge to scale-up production for practical applications due to the inherently limited throughput of micro-scale devices. To address this problem, we have developed a self-contained microchip that integrates many (N = 512) micro-scale droplet makers. This 3 × 3 cm2 PDMS microchip consists of a two-dimensional array of 32 × 16 flow-focusing droplet makers, a network of flow channels that connect them, and only two inputs and one output. The key innovation of this technology is the hybrid use of both soft-lithography and direct laser-micromachining. The microscale resolution of soft lithography is used to fabricate flow-focusing droplet makers that can produce small and precisely defined droplets. Deeply engraved (h ≈ 500 μm) laser-machined channels are utilized to supply each of the droplet makers with its oil phase, aqueous phase, and access to an output channel. The engraved channels' low hydrodynamic resistance ensures that each droplet maker is driven with the same flow rates for highly uniform droplet formation.To demonstrate the utility of this approach, water droplets (d ≈ 80 μm) were generated in hexadecane on both 8 × 1 and 32 × 16 geometries. PMID:24166156

The Accuracy and Precision of Flow Measurements Using Phase Contrast Techniques

NASA Astrophysics Data System (ADS)

Tang, Chao

Quantitative volume flow rate measurements using the magnetic resonance imaging technique are studied in this dissertation because the volume flow rates have a special interest in the blood supply of the human body. The method of quantitative volume flow rate measurements is based on the phase contrast technique, which assumes a linear relationship between the phase and flow velocity of spins. By measuring the phase shift of nuclear spins and integrating velocity across the lumen of the vessel, we can determine the volume flow rate. The accuracy and precision of volume flow rate measurements obtained using the phase contrast technique are studied by computer simulations and experiments. The various factors studied include (1) the partial volume effect due to voxel dimensions and slice thickness relative to the vessel dimensions; (2) vessel angulation relative to the imaging plane; (3) intravoxel phase dispersion; (4) flow velocity relative to the magnitude of the flow encoding gradient. The partial volume effect is demonstrated to be the major obstacle to obtaining accurate flow measurements for both laminar and plug flow. Laminar flow can be measured more accurately than plug flow in the same condition. Both the experiment and simulation results for laminar flow show that, to obtain the accuracy of volume flow rate measurements to within 10%, at least 16 voxels are needed to cover the vessel lumen. The accuracy of flow measurements depends strongly on the relative intensity of signal from stationary tissues. A correction method is proposed to compensate for the partial volume effect. The correction method is based on a small phase shift approximation. After the correction, the errors due to the partial volume effect are compensated, allowing more accurate results to be obtained. An automatic program based on the correction method is developed and implemented on a Sun workstation. The correction method is applied to the simulation and experiment results. The results show that the correction significantly reduces the errors due to the partial volume effect. We apply the correction method to the data of in vivo studies. Because the blood flow is not known, the results of correction are tested according to the common knowledge (such as cardiac output) and conservation of flow. For example, the volume of blood flowing to the brain should be equal to the volume of blood flowing from the brain. Our measurement results are very convincing.

A device for automatic photoelectric control of the analytical gap for emission spectrographs

USGS Publications Warehouse

Dietrich, John A.; Cooley, Elmo F.; Curry, Kenneth J.

1977-01-01

A photoelectric device has been built that automatically controls the analytical gap between electrodes during excitation period. The control device allows for precise control of the analytical gap during the arcing process of samples, resulting in better precision of analysis.

Mount Etna eruptions of the last 2,750 years: revised chronology and location through archeomagnetic and 226Ra-230Th dating

NASA Astrophysics Data System (ADS)

Tanguy, Jean-Claude; Condomines, Michel; Le Goff, Maxime; Chillemi, Vito; La Delfa, Santo; Patanè, Giuseppe

2007-09-01

A careful re-examination of the well-known written documents pertaining to the 2,750-year-long historical period of Mount Etna was carried out and their interpretation checked through the high-accuracy archeomagnetic method (>1,200 large samples), combined with the 226Ra-230Th radiochronology. The magnetic dating is based upon secular variation of the direction of the geomagnetic field (DGF) and estimated to reach a precision of ±40 years for the last 1,200 years, and ±100 to 200 years up to circa 150 B.C. Although less precise, the 226Ra-230Th method provides a unique tool for distinguishing between historic and prehistoric lavas, which in some cases might have similar DGFs. We show that despite the abundance of details on ancient historical eruptions, the primary sources of information are often too imprecise to identify their lava flows and eruptive systems. Most of the ages of these lavas, which are today accepted on the geological maps and catalogues, were attributed in the 1800s on the basis of their morphology and without any stratigraphical control. In fact, we found that 80% of the “historically dated” flows and cones prior to the 1700s are usually several hundreds of years older than recorded, the discrepancies sometimes exceeding a millennium. This is proper the case for volcanics presumed of the “1651 east” (actually ˜1020), “1595” (actually two distinct flows, respectively, ˜1200 and ˜1060), “1566” (˜1180), “1536” (two branches dated ˜1250 and ˜950), “1444” (a branch dated ˜1270), “1408” (lower branches dated ˜450 and ˜350), “1381” (˜1160), “1329” (˜1030), “1284” (˜1450 and ˜700), “1169 or 812” (˜1000) eruptions. Conversely, well-preserved cones and flows that are undated on the maps were produced by recent eruptions that went unnoticed in historical accounts, especially during the Middle Ages. For the few eruptions that are recorded between A.D. 252 and 750 B.C., none of their presumed lava flows shows a DGF in agreement with that existing at their respective dates of occurrence, most of these flows being in fact prehistoric. The cinder cones of Monpeloso (presumed “A.D. 252”) and Mt. Gorna (“394 B.C.”), although roughly consistent magnetically and radiochronologically with their respective epochs, remain of unspecified age because of a lack of precision of the DGF reference curve at the time. It is concluded that at the time scale of the last millennia, Mount Etna does not provide evidence of a steady-state behavior. Periods of voluminous eruptions lasting 50 to 150 years (e.g., A.D. 300 450, 950 1060, 1607 1669) are followed by centuries of less productive activity, although at any time a violent outburst may occur. Such a revised history should be taken into account for eruptive models, magma output, internal plumbing of the volcano, petrological evolution, volcano mapping and civil protection.

Relative ages of lava flows at Alba Patera, Mars

NASA Technical Reports Server (NTRS)

Schneeberger, Dale M.; Pieri, David C.

1987-01-01

Many large lava flows on the flanks of Alba Patera are astonishing in their volume and length. As a suite, these flows suggest tremendously voluminous and sustained eruptions, and provide dimensional boundary conditions typically a factor of 100 larger than terrestrial flows. One of the most striking features associated with Alba Patera is the large, radially oriented lava flows that exhibit a variety of flow morphologies. These include sheet flows, tube fed and tube channel flows, and undifferentiated flows. Three groups of flows were studied; flows on the northwest flank, southeast flank, and the intracaldera region. The lava flows discussed probably were erupted as a group during the same major volcanic episode as suggested by the data presented. Absolute ages are poorly constrained for both the individual flows and shield, due in part to disagreement as to which absolute age curve is representative for Mars. A relative age sequence is implied but lacks precision due to the closeness of the size frequency curves.

Evaluation of Aerosol Optical Thickness algorithm for Geostationary Environmental Monitoring Spectrometer (GEMS) Using the OMI Instrument over East Asia

NASA Astrophysics Data System (ADS)

Go, S.; Kim, J.; KIM, M.; Choi, M.; Lim, H.; Torres, O.; Chang, L.; Hong, J.

2016-12-01

Nitrous oxide (N2O) is a powerful greenhouse gas and ozone depleting substance. With high atmospheric backgrounds and small relative signals, N2O emissions have been challenging to observe and understand on regional scales with traditional instrumentation. Fast-response airborne measurements with high precision and accuracy can potentially bridge this observational gap. Here we present flight assessments of a new flight system based on an Aerodyne mini-spectrometer as well as a Los Gatos N2O/CO analyzer during the Fertilizer Emissions Airborne Study (FEAST). With the Scientific Aviation Mooney aircraft, we conducted test flights for both analyzers where a known calibration gas was sampled throughout the flight (`null' tests). Clear altitude/cabin-pressure dependencies were observed for both analyzers if operated in an "off-the-shelf' manner. For the remainder of test flights and the FEAST campaign we used a new flight system based on an Aerodyne mini-spectrometer with the addition of a custom pressure control/calibration system. Instead of using traditional approaches with spectral-zeros and infrequent in-flight calibrations, we employ a high-flow system with stable flow control to enable high frequency (2 minutes), short duration (15 seconds) sampling of a known calibration gas. This approach, supported by the null test, enables correction for spectral drift caused by a variety of factors while maintaining a 90% duty cycle for 1Hz sampling from an aircraft. Preliminary in-flight precisions are estimated at 0.05 ppb, 0.1 ppm, 1 ppb, and 10 ppm for N2O, CO2, CO, and H2O respectively. We also present a further 40 hours of inter-comparison in flight with a Picarro 2301-f ring-down spectrometer demonstrating consistency between CO2 and H2O measurements and no altitude dependent error.

Airborne testing and demonstration of a new flight system based on an Aerodyne N2O-CO2-CO-H2O mini-spectrometer

NASA Astrophysics Data System (ADS)

Gvakharia, A.; Kort, E. A.; Smith, M. L.; Conley, S.

2017-12-01

Nitrous oxide (N2O) is a powerful greenhouse gas and ozone depleting substance. With high atmospheric backgrounds and small relative signals, N2O emissions have been challenging to observe and understand on regional scales with traditional instrumentation. Fast-response airborne measurements with high precision and accuracy can potentially bridge this observational gap. Here we present flight assessments of a new flight system based on an Aerodyne mini-spectrometer as well as a Los Gatos N2O/CO analyzer during the Fertilizer Emissions Airborne Study (FEAST). With the Scientific Aviation Mooney aircraft, we conducted test flights for both analyzers where a known calibration gas was sampled throughout the flight (`null' tests). Clear altitude/cabin-pressure dependencies were observed for both analyzers if operated in an "off-the-shelf' manner. For the remainder of test flights and the FEAST campaign we used a new flight system based on an Aerodyne mini-spectrometer with the addition of a custom pressure control/calibration system. Instead of using traditional approaches with spectral-zeros and infrequent in-flight calibrations, we employ a high-flow system with stable flow control to enable high frequency (2 minutes), short duration (15 seconds) sampling of a known calibration gas. This approach, supported by the null test, enables correction for spectral drift caused by a variety of factors while maintaining a 90% duty cycle for 1Hz sampling from an aircraft. Preliminary in-flight precisions are estimated at 0.05 ppb, 0.1 ppm, 1 ppb, and 10 ppm for N2O, CO2, CO, and H2O respectively. We also present a further 40 hours of inter-comparison in flight with a Picarro 2301-f ring-down spectrometer demonstrating consistency between CO2 and H2O measurements and no altitude dependent error.

A cooperative program to stimulate student involvement through the MIT Undergraduate Research Opportunity Program

NASA Technical Reports Server (NTRS)

1984-01-01

Flow characteristics in the low speed Wright Brothers Wind Tunnel were studied. Calculations to check the precision of the tunnel were conducted. A program for generating computational grids around an airfoil was developed and compared with the wind tunnel model. Low Reynolds number flow phenomenon of periodic vortex shedding in a wake were also studied by applying a hot-wire anomemeter.

A simple bubble-flowmeter with quasicontinuous registration.

PubMed

Ludt, H; Herrmann, H D

1976-07-22

The construction of a simple bubble-flow-meter is described. The instrument has the following features: 1. automatic bubble injection, 2. precise measurement of the bubble passage time by a digital counter, 3. quasicontinuous registration of the flow rate, 4. alternative run with clear fluid (water) and coloured fluid (blood), 5. low volume, 6. closed measuring system for measurements in low and high pressure systems.

Internal Flows in Free Drops (IFFD)

NASA Technical Reports Server (NTRS)

Trinh, E. H.; Sadhal, Satwindar S.; Thomas, D. A.; Crouch, R. K.

1998-01-01

Within the framework of an Earth-based research task investigating the internal flows within freely levitated drops, a low-gravity technology development experiment has been designed and carried out within the NASA Glovebox facility during the STS-83 and STS-94 Shuttle flights (MSL-1 mission). The goal was narrowly defined as the assessment of the capabilities of a resonant single-axis ultrasonic levitator to stably position free drops in the Shuttle environment with a precision required for the detailed measurement of internal flows. The results of this entirely crew-operated investigation indicate that the approach is fundamentally sound, but also that the ultimate stability of the positioning is highly dependent on the residual acceleration characteristic of the Spacecraft, and to a certain extent, on the initial drop deployment of the drop. The principal results are: the measured dependence of the residual drop rotation and equilibrium drop shape on the ultrasonic power level, the experimental evaluation of the typical drop translational stability in a realistic low-gravity environment, and the semi-quantitative evaluation of background internal flows within quasi-isothermal drops. Based on these results, we conclude that the successful design of a full-scale Microgravity experiment is possible, and would allow accurate the measurement of thermocapillary flows within transparent drops. The need has been demonstrated, however, for the capability for accurately deploying the drop, for a quiescent environment, and for precise mechanical adjustments of the levitator.

Design of high precision temperature control system for TO packaged LD

NASA Astrophysics Data System (ADS)

Liang, Enji; Luo, Baoke; Zhuang, Bin; He, Zhengquan

2017-10-01

Temperature is an important factor affecting the performance of TO package LD. In order to ensure the safe and stable operation of LD, a temperature control circuit for LD based on PID technology is designed. The MAX1978 and an external PID circuit are used to form a control circuit that drives the thermoelectric cooler (TEC) to achieve control of temperature and the external load can be changed. The system circuit has low power consumption, high integration and high precision,and the circuit can achieve precise control of the LD temperature. Experiment results show that the circuit can achieve effective and stable control of the laser temperature.

High-Precision 40Ar/39Ar dating of the Deccan Traps

NASA Astrophysics Data System (ADS)

Sprain, C. J.; Renne, P. R.; Richards, M. A.; Self, S.; Vanderkluysen, L.; Pande, K.; Morgan, L. E.; Cosca, M. A.

2015-12-01

The Deccan Traps (DT) have been strongly implicated over the past thirty years as a potential cause of the mass extinctions at the Cretaceous-Paleogene boundary (KPB). While a broad coincidence between the DT eruptions and the KPB is increasingly clear, variables such as tempo, volume of eruptions, and amount of associated climate-modifying volatiles, are too poorly constrained to properly assess causality. In order to appropriately test whether the DT played a role in the mass extinctions a high-precision geochronologic framework defining the timing and tempo of volcanic eruptions is needed. Recent high-precision U/Pb dating of zircons from inferred paleosols (red boles) and melt segregation horizons is the only available geochronology of the DT that is sufficiently precise to resolve age differences of less than 100 ka (Schoene et al., 2015). While this technique can achieve high-precision dates for individual zircon crystals, protracted age distributions may not include the actual eruption age. Moreover, the applicability of U/Pb dating in the DT is limited as suitable material is only sporadically present and therefore the technique is unlikely to achieve the resolution necessary to assess the tempo of DT eruptions. To mediate these limitations, we present new high-precision 40Ar/39Ar ages for plagioclase separated from the lava flows sampled from each of ten chemostratigraphically-defined formations within the Western Ghats. Multiple (N = 1-4) plateau ages from each sample and detailed neutron fluence monitoring during irradiation yield ages with precision commonly better than 100 ka (1 sigma). Results provide the first precise location of the KPB within the DT eruption sequence, which approximately coincides with major changes in eruption frequency, flow-field volumes, extent of crustal contamination, and degree of fractionation. Collectively, these results suggest that a state shift occurred in the DT magma system within ~50 ka of the Chicxulub impact, consistent with transient effects of seismic energy associated with the impact. Further, our new data invalidate the concept of three discrete eruption pulses in the Western Ghats (Chenet et al., 2007, 2009; Keller et al., 2008) and rather indicate only a sharp increase in mean volumetric eruption rates near the KPB.

Design and control of a high precision drive mechanism

NASA Astrophysics Data System (ADS)

Pan, Bo; He, Yongqiang; Wang, Haowei; Zhang, Shuyang; Zhang, Donghua; Wei, Xiaorong; Jiang, Zhihong

2017-01-01

This paper summarizes the development of a high precision drive mechanism (HPDM) for space application, such as the directional antenna, the laser communication device, the mobile camera and other pointing mechanisms. In view of the great practical significance of high precision drive system, control technology for permanent magnet synchronous motor (PMSM) servo system is also studied and a PMSM servo controller is designed in this paper. And the software alignment was applied to the controller to eliminate the steady error of the optical encoder, which helps to realize the 1 arcsec (1σ) control precision. To assess its capabilities, the qualification environment testing including the thermal vacuum cycling testing, and the sinusoidal and random vibration were carried out. The testing results show that the performance of the HPDM is almost the same between the former and the end of each testing.

Spacecraft Attitude Tracking and Maneuver Using Combined Magnetic Actuators

NASA Technical Reports Server (NTRS)

Zhou, Zhiqiang

2012-01-01

A paper describes attitude-control algorithms using the combination of magnetic actuators with reaction wheel assemblies (RWAs) or other types of actuators such as thrusters. The combination of magnetic actuators with one or two RWAs aligned with different body axis expands the two-dimensional control torque to three-dimensional. The algorithms can guarantee the spacecraft attitude and rates to track the commanded attitude precisely. A design example is presented for nadir-pointing, pitch, and yaw maneuvers. The results show that precise attitude tracking can be reached and the attitude- control accuracy is comparable with RWA-based attitude control. When there are only one or two workable RWAs due to RWA failures, the attitude-control system can switch to the control algorithms for the combined magnetic actuators with the RWAs without going to the safe mode, and the control accuracy can be maintained. The attitude-control algorithms of the combined actuators are derived, which can guarantee the spacecraft attitude and rates to track the commanded values precisely. Results show that precise attitude tracking can be reached, and the attitude-control accuracy is comparable with 3-axis wheel control.

System level modeling and component level control of fuel cells

NASA Astrophysics Data System (ADS)

Xue, Xingjian

This dissertation investigates the fuel cell systems and the related technologies in three aspects: (1) system-level dynamic modeling of both PEM fuel cell (PEMFC) and solid oxide fuel cell (SOFC); (2) condition monitoring scheme development of PEM fuel cell system using model-based statistical method; and (3) strategy and algorithm development of precision control with potential application in energy systems. The dissertation first presents a system level dynamic modeling strategy for PEM fuel cells. It is well known that water plays a critical role in PEM fuel cell operations. It makes the membrane function appropriately and improves the durability. The low temperature operating conditions, however, impose modeling difficulties in characterizing the liquid-vapor two phase change phenomenon, which becomes even more complex under dynamic operating conditions. This dissertation proposes an innovative method to characterize this phenomenon, and builds a comprehensive model for PEM fuel cell at the system level. The model features the complete characterization of multi-physics dynamic coupling effects with the inclusion of dynamic phase change. The model is validated using Ballard stack experimental result from open literature. The system behavior and the internal coupling effects are also investigated using this model under various operating conditions. Anode-supported tubular SOFC is also investigated in the dissertation. While the Nernst potential plays a central role in characterizing the electrochemical performance, the traditional Nernst equation may lead to incorrect analysis results under dynamic operating conditions due to the current reverse flow phenomenon. This dissertation presents a systematic study in this regard to incorporate a modified Nernst potential expression and the heat/mass transfer into the analysis. The model is used to investigate the limitations and optimal results of various operating conditions; it can also be utilized to perform the optimal design of tubular SOFC. With the system-level dynamic model as a basis, a framework for the robust, online monitoring of PEM fuel cell is developed in the dissertation. The monitoring scheme employs the Hotelling T2 based statistical scheme to handle the measurement noise and system uncertainties and identifies the fault conditions through a series of self-checking and conformal testing. A statistical sampling strategy is also utilized to improve the computation efficiency. Fuel/gas flow control is the fundamental operation for fuel cell energy systems. In the final part of the dissertation, a high-precision and robust tracking control scheme using piezoelectric actuator circuit with direct hysteresis compensation is developed. The key characteristic of the developed control algorithm includes the nonlinear continuous control action with the adaptive boundary layer strategy.

Microfluidic Assisted Synthesis of Multipurpose Polymer Nanoassembly Particles for Fluorescence, LSPR, and SERS Activities.

PubMed

Visaveliya, Nikunjkumar; Köhler, J Michael

2015-12-22

Potential biomedical applications such as controlled delivery with sustained drug release profile demand for multifunctional polymeric particles of precise chemical composition and with welldefined physicochemical properties. The real challenge is to obtain the reproducible and homogeneous nanoparticles in a minimum number of preparation steps. Here, single-step nanoarchitectures of soft surface layered copolymer nanoparticles with a regular tuning in the size via micro flow-through assisted synthesis are reported. Interfacial copolymerization induces the controlled compartmentalization where a hydrophobic core adopts spherical shape in order to minimize the surface energy and simultaneously shelter in the hydrophilic shelllike surface layer. Surface layer can swell in the aqueous medium and allow controlled entrapping of functional hydrophobic nanoparticles in the hydrophilic interior via electrostatic interaction which can be particularly interesting for combined fluorescence activity. Furthermore, the nanoarchitecture of size and concentration controlled polymer-metal nanoassembly particles can be implemented as an ideal surface-enhanced Raman scattering substrate for detection of the trace amounts of various analytes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controllable deformation of salt water-filled carbon nanotubes using an electric field with application to molecular sieving

NASA Astrophysics Data System (ADS)

Ye, Hongfei; Zheng, Yonggang; Zhang, Zhongqiang; Zhang, Hongwu; Chen, Zhen

2016-08-01

Precisely controlling the deformation of carbon nanotubes (CNTs) has practical application in the development of nanoscale functional devices, although it is a challenging task. Here, we propose a novel method to guide the deformation of CNTs through filling them with salt water and applying an electric field. With the electric field along the axial direction, the height of CNTs is enlarged by the axial electric force due to the internal ions and polar water molecules. Under an electric field with two mutually orthogonal components, the transverse electric force could further induce the bending deformation of CNTs. Based on the classical rod and beam theories, two mechanical models are constructed to verify and quantitatively describe the relationships between the tension and bending deformations of CNTs and the electric field intensity. Moreover, by means of the electric field-driven tension behavior of CNTs, we design a stretchable molecular sieve to control the flow rate of mixed gas and collect a single high-purity gas. The present work opens up new avenues in the design and fabrication of nanoscale controlling units.

SyPRID sampler: A large-volume, high-resolution, autonomous, deep-ocean precision plankton sampling system

NASA Astrophysics Data System (ADS)

Billings, Andrew; Kaiser, Carl; Young, Craig M.; Hiebert, Laurel S.; Cole, Eli; Wagner, Jamie K. S.; Van Dover, Cindy Lee

2017-03-01

The current standard for large-volume (thousands of cubic meters) zooplankton sampling in the deep sea is the MOCNESS, a system of multiple opening-closing nets, typically lowered to within 50 m of the seabed and towed obliquely to the surface to obtain low-spatial-resolution samples that integrate across 10 s of meters of water depth. The SyPRID (Sentry Precision Robotic Impeller Driven) sampler is an innovative, deep-rated (6000 m) plankton sampler that partners with the Sentry Autonomous Underwater Vehicle (AUV) to obtain paired, large-volume plankton samples at specified depths and survey lines to within 1.5 m of the seabed and with simultaneous collection of sensor data. SyPRID uses a perforated Ultra-High-Molecular-Weight (UHMW) plastic tube to support a fine mesh net within an outer carbon composite tube (tube-within-a-tube design), with an axial flow pump located aft of the capture filter. The pump facilitates flow through the system and reduces or possibly eliminates the bow wave at the mouth opening. The cod end, a hollow truncated cone, is also made of UHMW plastic and includes a collection volume designed to provide an area where zooplankton can collect, out of the high flow region. SyPRID attaches as a saddle-pack to the Sentry vehicle. Sentry itself is configured with a flight control system that enables autonomous survey paths to low altitudes. In its verification deployment at the Blake Ridge Seep (2160 m) on the US Atlantic Margin, SyPRID was operated for 6 h at an altitude of 5 m. It recovered plankton samples, including delicate living larvae, from the near-bottom stratum that is seldom sampled by a typical MOCNESS tow. The prototype SyPRID and its next generations will enable studies of plankton or other particulate distributions associated with localized physico-chemical strata in the water column or above patchy habitats on the seafloor.

Flight Test Techniques Used to Evaluate Performance Benefits During Formation Flight

NASA Technical Reports Server (NTRS)

Ray, Ronald J.; Cobleigh, Brent R.; Vachon, M. Jake; SaintJohn, Clinton

2002-01-01

The Autonomous Formation Flight research project has been implemented at the NASA Dryden Flight Research Center to demonstrate the benefits of formation flight and develop advanced technologies to facilitate exploiting these benefits. Two F/A-18 aircraft have been modified to precisely control and monitor relative position, and to determine performance of the trailing airplane. Flight test maneuvers and analysis techniques have been developed to determine the performance advantages, including drag and fuel flow reductions and improvements in range factor. By flying the trailing airplane through a matrix of lateral, longitudinal, and vertical offset positions, a detailed map of the performance benefits has been obtained at two flight conditions. Significant performance benefits have been obtained during this flight test phase. Drag reductions of more than 20 percent and fuel flow reductions of more than 18 percent have been measured at flight conditions of Mach 0.56 and an altitude of 25,000 ft. The results show favorable agreement with published theory and generic predictions. An F/A-18 long-range cruise mission at Mach 0.8 and an altitude of 40,000 ft has been simulated in the optimum formation position and has demonstrated a 14-percent fuel reduction when compared with a controlled chase airplane of similar configuration.

A fluorescence-based centrifugal microfluidic system for parallel detection of multiple allergens

NASA Astrophysics Data System (ADS)

Chen, Q. L.; Ho, H. P.; Cheung, K. L.; Kong, S. K.; Suen, Y. K.; Kwan, Y. W.; Li, W. J.; Wong, C. K.

2010-02-01

This paper reports a robust polymer based centrifugal microfluidic analysis system that can provide parallel detection of multiple allergens in vitro. Many commercial food products (milk, bean, pollen, etc.) may introduce allergy to people. A low-cost device for rapid detection of allergens is highly desirable. With this as the objective, we have studied the feasibility of using a rotating disk device incorporating centrifugal microfluidics for performing actuationfree and multi-analyte detection of different allergen species with minimum sample usage and fast response time. Degranulation in basophils or mast cells is an indicator to demonstrate allergic reaction. In this connection, we used acridine orange (AO) to demonstrate degranulation in KU812 human basophils. It was found that the AO was released from granules when cells were stimulated by ionomycin, thus signifying the release of histamine which accounts for allergy symptoms [1-2]. Within this rotating optical platform, major microfluidic components including sample reservoirs, reaction chambers, microchannel and flow-control compartments are integrated into a single bio-compatible polydimethylsiloxane (PDMS) substrate. The flow sequence and reaction time can be controlled precisely. Sequentially through varying the spinning speed, the disk may perform a variety of steps on sample loading, reaction and detection. Our work demonstrates the feasibility of using centrifugation as a possible immunoassay system in the future.

Tunable optical limiting optofluidic device filled with graphene oxide dispersion in ethanol

PubMed Central

Fang, Chaolong; Dai, Bo; Hong, Ruijin; Tao, Chunxian; Wang, Qi; Wang, Xu; Zhang, Dawei; Zhuang, Songlin

2015-01-01

An optofluidic device with tunable optical limiting property is proposed and demonstrated. The optofluidic device is designed for adjusting the concentration of graphene oxide (GO) in the ethanol solution and fabricated by photolithography technique. By controlling the flow rate ratio of the injection, the concentration of GO can be precisely adjusted so that the optical nonlinearity can be changed. The nonlinear optical properties and dynamic excitation relaxation of the GO/ethanol solution are investigated by using Z-scan and pump-probe measurements in the femtosecond regime within the 1.5 μm telecom band. The GO/ethanol solution presents ultrafast recovery time. Besides, the optical limiting property is in proportion to the concentration of the solution. Thus, the threshold power and the saturated power of the optical limiting property can be simply and efficiently manipulated by controlling the flow rate ratio of the injection. Furthermore, the amplitude regeneration is demonstrated by employing the proposed optofluidic device. The signal quality of intensity-impaired femtosecond pulse is significantly improved. The optofluidic device is compact and has long interaction length of optical field and nonlinear material. Heat can be dissipated in the solution and nonlinear material is isolated from other optical components, efficiently avoiding thermal damage and mechanical damage. PMID:26477662

Design, Fabrication, and In Vitro Testing of an Anti-biofouling Glaucoma Micro-shunt.

PubMed

Harake, Ryan S; Ding, Yuzhe; Brown, J David; Pan, Tingrui

2015-10-01

Glaucoma, one of the leading causes of irreversible blindness, is a progressive neurodegenerative disease. Chronic elevated intraocular pressure (IOP), a prime risk factor for glaucoma, can be treated by aqueous shunts, implantable devices, which reduce IOP in glaucoma patients by providing alternative aqueous outflow pathways. Although initially effective at delaying glaucoma progression, contemporary aqueous shunts often lead to numerous complications and only 50% of implanted devices remain functional after 5 years. In this work, we introduce a novel micro-device which provides an innovative platform for IOP reduction in glaucoma patients. The device design features an array of parallel micro-channels to provide precision aqueous outflow resistance control. Additionally, the device's microfluidic channels are composed of a unique combination of polyethylene glycol materials in order to provide enhanced biocompatibility and resistance to problematic channel clogging from biofouling of aqueous proteins. The microfabrication process employed to produce the devices results in additional advantages such as enhanced device uniformity and increased manufacturing throughput. Surface characterization experimental results show the device's surfaces exhibit significantly less non-specific protein adsorption compared to traditional implant materials. Results of in vitro flow experiments verify the device's ability to provide aqueous resistance control, continuous long-term stability through 10-day protein flow testing, and safety from risk of infection due to bacterial ingression.

Direct determination of cadmium in foods by solid sampling electrothermal vaporization inductively coupled plasma mass spectrometry using a tungsten coil trap

NASA Astrophysics Data System (ADS)

Zhang, Ying; Mao, Xuefei; Liu, Jixin; Wang, Min; Qian, Yongzhong; Gao, Chengling; Qi, Yuehan

2016-04-01

In this work, a solid sampling device consisting of a tungsten coil trap, porous carbon vaporizer and on-line ashing furnace of a Ni-Cr coil was interfaced with inductively coupled plasma mass spectrometry (ICP-MS). A modified double gas circuit system was employed that was composed of carrier and supplemental gas lines controlled by separate gas mass flow controllers. For Cd determination in food samples using the assembled solid sampling ICP-MS, the optimal ashing and vaporization conditions, flow rate of the argon-hydrogen (Ar/H2) (v:v = 24:1) carrier gas and supplemental gas, and minimum sampling mass were investigated. Under the optimized conditions, the limit of quantification was 0.5 pg and the relative standard deviation was within a 10.0% error range (n = 10). Furthermore, the mean spiked recoveries for various food samples were 99.4%-105.9% (n = 6). The Cd concentrations measured by the proposed method were all within the certified values of the reference materials or were not significantly different (P > 0.05) from those of the microwave digestion ICP-MS method, demonstrating the good accuracy and precision of the solid sampling ICP-MS method for Cd determination in food samples.

Intelligent process control of fiber chemical vapor deposition

NASA Astrophysics Data System (ADS)

Jones, John Gregory

Chemical Vapor Deposition (CVD) is a widely used process for the application of thin films. In this case, CVD is being used to apply a thin film interface coating to single crystal monofilament sapphire (Alsb2Osb3) fibers for use in Ceramic Matrix Composites (CMC's). The hot-wall reactor operates at near atmospheric pressure which is maintained using a venturi pump system. Inert gas seals obviate the need for a sealed system. A liquid precursor delivery system has been implemented to provide precise stoichiometry control. Neural networks have been implemented to create real-time process description models trained using data generated based on a Navier-Stokes finite difference model of the process. Automation of the process to include full computer control and data logging capability is also presented. In situ sensors including a quadrupole mass spectrometer, thermocouples, laser scanner, and Raman spectrometer have been implemented to determine the gas phase reactants and coating quality. A fuzzy logic controller has been developed to regulate either the gas phase or the in situ temperature of the reactor using oxygen flow rate as an actuator. Scanning electron microscope (SEM) images of various samples are shown. A hierarchical control structure upon which the control structure is based is also presented.

Quantitative laser speckle flowmetry of the in vivo microcirculation using sidestream dark field microscopy

PubMed Central

Nadort, Annemarie; Woolthuis, Rutger G.; van Leeuwen, Ton G.; Faber, Dirk J.

2013-01-01

We present integrated Laser Speckle Contrast Imaging (LSCI) and Sidestream Dark Field (SDF) flowmetry to provide real-time, non-invasive and quantitative measurements of speckle decorrelation times related to microcirculatory flow. Using a multi exposure acquisition scheme, precise speckle decorrelation times were obtained. Applying SDF-LSCI in vitro and in vivo allows direct comparison between speckle contrast decorrelation and flow velocities, while imaging the phantom and microcirculation architecture. This resulted in a novel analysis approach that distinguishes decorrelation due to flow from other additive decorrelation sources. PMID:24298399

Numerical simulations of the charged-particle flow dynamics for sources with a curved emission surface

NASA Astrophysics Data System (ADS)

Altsybeyev, V. V.

2016-12-01

The implementation of numerical methods for studying the dynamics of particle flows produced by pulsed sources is discussed. A particle tracking method with so-called gun iteration for simulations of beam dynamics is used. For the space charge limited emission problem, we suggest a Gauss law emission model for precise current-density calculation in the case of a curvilinear emitter. The results of numerical simulations of particle-flow formation for cylindrical bipolar diode and for diode with elliptical emitter are presented.

Three-Dimensional Printing Based Hybrid Manufacturing of Microfluidic Devices.

PubMed

Alapan, Yunus; Hasan, Muhammad Noman; Shen, Richang; Gurkan, Umut A

2015-05-01

Microfluidic platforms offer revolutionary and practical solutions to challenging problems in biology and medicine. Even though traditional micro/nanofabrication technologies expedited the emergence of the microfluidics field, recent advances in advanced additive manufacturing hold significant potential for single-step, stand-alone microfluidic device fabrication. One such technology, which holds a significant promise for next generation microsystem fabrication is three-dimensional (3D) printing. Presently, building 3D printed stand-alone microfluidic devices with fully embedded microchannels for applications in biology and medicine has the following challenges: (i) limitations in achievable design complexity, (ii) need for a wider variety of transparent materials, (iii) limited z-resolution, (iv) absence of extremely smooth surface finish, and (v) limitations in precision fabrication of hollow and void sections with extremely high surface area to volume ratio. We developed a new way to fabricate stand-alone microfluidic devices with integrated manifolds and embedded microchannels by utilizing a 3D printing and laser micromachined lamination based hybrid manufacturing approach. In this new fabrication method, we exploit the minimized fabrication steps enabled by 3D printing, and reduced assembly complexities facilitated by laser micromachined lamination method. The new hybrid fabrication method enables key features for advanced microfluidic system architecture: (i) increased design complexity in 3D, (ii) improved control over microflow behavior in all three directions and in multiple layers, (iii) transverse multilayer flow and precisely integrated flow distribution, and (iv) enhanced transparency for high resolution imaging and analysis. Hybrid manufacturing approaches hold great potential in advancing microfluidic device fabrication in terms of standardization, fast production, and user-independent manufacturing.