Incremental passivity and output regulation for switched nonlinear systems

NASA Astrophysics Data System (ADS)

Pang, Hongbo; Zhao, Jun

2017-10-01

This paper studies incremental passivity and global output regulation for switched nonlinear systems, whose subsystems are not required to be incrementally passive. A concept of incremental passivity for switched systems is put forward. First, a switched system is rendered incrementally passive by the design of a state-dependent switching law. Second, the feedback incremental passification is achieved by the design of a state-dependent switching law and a set of state feedback controllers. Finally, we show that once the incremental passivity for switched nonlinear systems is assured, the output regulation problem is solved by the design of global nonlinear regulator controllers comprising two components: the steady-state control and the linear output feedback stabilising controllers, even though the problem for none of subsystems is solvable. Two examples are presented to illustrate the effectiveness of the proposed approach.

A passivity criterion for sampled-data bilateral teleoperation systems.

PubMed

Jazayeri, Ali; Tavakoli, Mahdi

2013-01-01

A teleoperation system consists of a teleoperator, a human operator, and a remote environment. Conditions involving system and controller parameters that ensure the teleoperator passivity can serve as control design guidelines to attain maximum teleoperation transparency while maintaining system stability. In this paper, sufficient conditions for teleoperator passivity are derived for when position error-based controllers are implemented in discrete-time. This new analysis is necessary because discretization causes energy leaks and does not necessarily preserve the passivity of the system. The proposed criterion for sampled-data teleoperator passivity imposes lower bounds on the teleoperator's robots dampings, an upper bound on the sampling time, and bounds on the control gains. The criterion is verified through simulations and experiments.

Aspects and Some Results on Passivity and Positivity of Dynamic Systems

NASA Astrophysics Data System (ADS)

De la Sen, M.

2017-12-01

This paper is devoted to discuss certain aspects of passivity results in dynamic systems and the characterization of the regenerative systems counterparts. In particular, the various concepts of passivity as standard passivity, strict input passivity, strict output passivity and very strict passivity (i.e. joint strict input and output passivity) are given and related to the existence of a storage function and a dissipation function. Later on, the obtained results are related to external positivity of systems and positivity or strict positivity of the transfer matrices and transfer functions in the time-invariant case. On the other hand, it is discussed how to achieve or how eventually to increase the passivity effects via linear feedback by the synthesis of the appropriate feed-forward or feedback controllers or, simply, by adding a positive parallel direct input-output matrix interconnection gain.

Miniature DMFCs with passive thermal-fluids management system

NASA Astrophysics Data System (ADS)

Guo, Zhen; Faghri, Amir

A new miniature DMFC system that includes a fuel cell stack, a fuel tank and a passive ancillary system (termed "thermal-fluids management system" in this paper) is presented. The thermal-fluids management system utilizes passive approaches for fuel storage and delivery, air breathing, water management, CO 2 release and thermal management. With 5.1 g of neat methanol in the fuel cartridge, a prototype has successfully demonstrated 18 h of continuous operation with total power output of 1.56 Wh.

Passive cooling system for top entry liquid metal cooled nuclear reactors

DOEpatents

Boardman, Charles E.; Hunsbedt, Anstein; Hui, Marvin M.

1992-01-01

A liquid metal cooled nuclear fission reactor plant having a top entry loop joined satellite assembly with a passive auxiliary safety cooling system for removing residual heat resulting from fuel decay during shutdown, or heat produced during a mishap. This satellite type reactor plant is enhanced by a backup or secondary passive safety cooling system which augments the primary passive auxiliary cooling system when in operation, and replaces the primary cooling system when rendered inoperative.

Redesign of Water Distribution Systems for Passive ...

EPA Pesticide Factsheets

Journal article The purpose of this paper is to examine how water distribution systems could be designed or retrofitted to passively contain contaminants that might enter the water distribution system.

Passive cooling safety system for liquid metal cooled nuclear reactors

DOEpatents

Hunsbedt, Anstein; Boardman, Charles E.; Hui, Marvin M.; Berglund, Robert C.

1991-01-01

A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel. The passive cooling system includes a closed primary fluid circuit through the partitions surrounding the reactor vessel and a partially adjoining secondary open fluid circuit for carrying transferred heat out into the atmosphere.

Indirect passive cooling system for liquid metal cooled nuclear reactors

DOEpatents

Hunsbedt, Anstein; Boardman, Charles E.

1990-01-01

A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel. The passive cooling system includes a closed primary fluid circuit through the partitions surrounding the reactor vessel and a partially adjoining secondary open fluid circuit for carrying transferred heat out into the atmosphere.

Liquid metal cooled nuclear reactors with passive cooling system

DOEpatents

Hunsbedt, Anstein; Fanning, Alan W.

1991-01-01

A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of cooling medium flow circuits which cooperate to remove and carry heat away from the fuel core upon loss of the normal cooling flow circuit to areas external thereto.

Synthesis of Optimal Constant-Gain Positive-Real Controllers for Passive Systems

NASA Technical Reports Server (NTRS)

Mao, Y.; Kelkar, A. G.; Joshi, S. M.

1999-01-01

This paper presents synthesis methods for the design of constant-gain positive real controllers for passive systems. The results presented in this paper, in conjunction with the previous work by the authors on passification of non-passive systems, offer a useful synthesis tool for the design of passivity-based robust controllers for non-passive systems as well. Two synthesis approaches are given for minimizing an LQ-type performance index, resulting in optimal controller gains. Two separate algorithms, one for each of these approaches, are given. The synthesis techniques are demonstrated using two numerical examples: control of a flexible structure and longitudinal control of a fighter aircraft.

Westinghouse Small Modular Reactor passive safety system response to postulated events

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

Smith, M. C.; Wright, R. F.

2012-07-01

The Westinghouse Small Modular Reactor (SMR) is an 800 MWt (>225 MWe) integral pressurized water reactor. This paper is part of a series of four describing the design and safety features of the Westinghouse SMR. This paper focuses in particular upon the passive safety features and the safety system response of the Westinghouse SMR. The Westinghouse SMR design incorporates many features to minimize the effects of, and in some cases eliminates the possibility of postulated accidents. The small size of the reactor and the low power density limits the potential consequences of an accident relative to a large plant. Themore » integral design eliminates large loop piping, which significantly reduces the flow area of postulated loss of coolant accidents (LOCAs). The Westinghouse SMR containment is a high-pressure, compact design that normally operates at a partial vacuum. This facilitates heat removal from the containment during LOCA events. The containment is submerged in water which also aides the heat removal and provides an additional radionuclide filter. The Westinghouse SMR safety system design is passive, is based largely on the passive safety systems used in the AP1000{sup R} reactor, and provides mitigation of all design basis accidents without the need for AC electrical power for a period of seven days. Frequent faults, such as reactivity insertion events and loss of power events, are protected by first shutting down the nuclear reaction by inserting control rods, then providing cold, borated water through a passive, buoyancy-driven flow. Decay heat removal is provided using a layered approach that includes the passive removal of heat by the steam drum and independent passive heat removal system that transfers heat from the primary system to the environment. Less frequent faults such as loss of coolant accidents are mitigated by passive injection of a large quantity of water that is readily available inside containment. An automatic depressurization system is

Passively damped vibration welding system and method

DOEpatents

Tan, Chin-An; Kang, Bongsu; Cai, Wayne W.; Wu, Tao

2013-04-02

A vibration welding system includes a controller, welding horn, an anvil, and a passive damping mechanism (PDM). The controller generates an input signal having a calibrated frequency. The horn vibrates in a desirable first direction at the calibrated frequency in response to the input signal to form a weld in a work piece. The PDM is positioned with respect to the system, and substantially damps or attenuates vibration in an undesirable second direction. A method includes connecting the PDM having calibrated properties and a natural frequency to an anvil of an ultrasonic welding system. Then, an input signal is generated using a weld controller. The method includes vibrating a welding horn in a desirable direction in response to the input signal, and passively damping vibration in an undesirable direction using the PDM.

Clinical outcome of calves with failure of passive transfer as diagnosed by a commercially available IgG quick test kit

PubMed Central

Stilwell, George; Carvalho, Rita C.

2011-01-01

The efficacy of an IgG quick test in detecting calves with failure of passive transfer was assessed. The test was carried out on 97 male calves, 38% of which were negative (IgG < 10 mg/mL). Morbidity and mortality due to infectious diseases were significantly higher in the negative group showing that the quick test is useful in identifying calves more susceptible to infectious disease. PMID:22043074

EPMOSt: An Energy-Efficient Passive Monitoring System for Wireless Sensor Networks

PubMed Central

Garcia, Fernando P.; Andrade, Rossana M. C.; Oliveira, Carina T.; de Souza, José Neuman

2014-01-01

Monitoring systems are important for debugging and analyzing Wireless Sensor Networks (WSN). In passive monitoring, a monitoring network needs to be deployed in addition to the network to be monitored, named the target network. The monitoring network captures and analyzes packets transmitted by the target network. An energy-efficient passive monitoring system is necessary when we need to monitor a WSN in a real scenario because the lifetime of the monitoring network is extended and, consequently, the target network benefits from the monitoring for a longer time. In this work, we have identified, analyzed and compared the main passive monitoring systems proposed for WSN. During our research, we did not identify any passive monitoring system for WSN that aims to reduce the energy consumption of the monitoring network. Therefore, we propose an Energy-efficient Passive MOnitoring SysTem for WSN named EPMOSt that provides monitoring information using a Simple Network Management Protocol (SNMP) agent. Thus, any management tool that supports the SNMP protocol can be integrated with this monitoring system. Experiments with real sensors were performed in several scenarios. The results obtained show the energy efficiency of the proposed monitoring system and the viability of using it to monitor WSN in real scenarios. PMID:24949639

Inherently safe passive gas monitoring system

DOEpatents

Cordaro, Joseph V.; Bellamy, John Stephen; Shuler, James M.; Shull, Davis J.; Leduc, Daniel R.

2016-09-06

Generally, the present disclosure is directed to gas monitoring systems that use inductive power transfer to safely power an electrically passive device included within a nuclear material storage container. In particular, the electrically passive device can include an inductive power receiver for receiving inductive power transfer through a wall of the nuclear material storage container. The power received by the inductive power receiver can be used to power one or more sensors included in the device. Thus, the device is not required to include active power generation components such as, for example, a battery, that increase the risk of a spark igniting flammable gases within the container.

Passive perception system for day/night autonomous off-road navigation

NASA Astrophysics Data System (ADS)

Rankin, Arturo L.; Bergh, Charles F.; Goldberg, Steven B.; Bellutta, Paolo; Huertas, Andres; Matthies, Larry H.

2005-05-01

Passive perception of terrain features is a vital requirement for military related unmanned autonomous vehicle operations, especially under electromagnetic signature management conditions. As a member of Team Raptor, the Jet Propulsion Laboratory developed a self-contained passive perception system under the DARPA funded PerceptOR program. An environmentally protected forward-looking sensor head was designed and fabricated in-house to straddle an off-the-shelf pan-tilt unit. The sensor head contained three color cameras for multi-baseline daytime stereo ranging, a pair of cooled mid-wave infrared cameras for nighttime stereo ranging, and supporting electronics to synchronize captured imagery. Narrow-baseline stereo provided improved range data density in cluttered terrain, while wide-baseline stereo provided more accurate ranging for operation at higher speeds in relatively open areas. The passive perception system processed stereo images and outputted over a local area network terrain maps containing elevation, terrain type, and detected hazards. A novel software architecture was designed and implemented to distribute the data processing on a 533MHz quad 7410 PowerPC single board computer under the VxWorks real-time operating system. This architecture, which is general enough to operate on N processors, has been subsequently tested on Pentium-based processors under Windows and Linux, and a Sparc based-processor under Unix. The passive perception system was operated during FY04 PerceptOR program evaluations at Fort A. P. Hill, Virginia, and Yuma Proving Ground, Arizona. This paper discusses the Team Raptor passive perception system hardware and software design, implementation, and performance, and describes a road map to faster and improved passive perception.

Passive fire building protection system evaluation (case study: millennium ict centre)

NASA Astrophysics Data System (ADS)

Rahman, Vinky; Stephanie

2018-03-01

Passive fire protection system is a system that refers to the building design, both regarding of architecture and structure. This system usually consists of structural protection that protects the structure of the building and prevents the spread of fire and facilitate the evacuation process in case of fire. Millennium ICT Center is the largest electronic shopping center in Medan, Indonesia. As a public building that accommodates the crowd, this building needs a fire protection system by the standards. Therefore, the purpose of this study is to evaluate passive fire protection system of Millennium ICT Center building. The study was conducted to describe the facts of the building as well as direct observation to the research location. The collected data is then processed using the AHP (Analytical Hierarchy Process) method in its weighting process to obtain the reliability value of passive fire protection fire system. The results showed that there are some components of passive fire protection system in the building, but some are still unqualified. The first section in your paper

A Passive Earth-Entry Capsule for Mars Sample Return

NASA Technical Reports Server (NTRS)

Mitcheltree, Robert A.; Kellas, Sotiris

1999-01-01

A combination of aerodynamic analysis and testing, aerothermodynamic analysis, structural analysis and testing, impact analysis and testing, thermal analysis, ground characterization tests, configuration packaging, and trajectory simulation are employed to determine the feasibility of an entirely passive Earth entry capsule for the Mars Sample Return mission. The design circumvents the potential failure modes of a parachute terminal descent system by replacing that system with passive energy absorbing material to cushion the Mars samples during ground impact. The suggested design utilizes a spherically blunted 45-degree half-angle cone forebody with an ablative heat shield. The primary structure is a hemispherical, composite sandwich enclosing carbon foam energy absorbing material. Though no demonstration test of the entire system is included, results of the tests and analysis presented indicate that the design is a viable option for the Mars Sample Return Mission.

Passive Superconducting Shielding: Experimental Results and Computer Models

NASA Technical Reports Server (NTRS)

Warner, B. A.; Kamiya, K.

2003-01-01

Passive superconducting shielding for magnetic refrigerators has advantages over active shielding and passive ferromagnetic shielding in that it is lightweight and easy to construct. However, it is not as easy to model and does not fail gracefully. Failure of a passive superconducting shield may lead to persistent flux and persistent currents. Unfortunately, modeling software for superconducting materials is not as easily available as is software for simple coils or for ferromagnetic materials. This paper will discuss ways of using available software to model passive superconducting shielding.

Failure detection system risk reduction assessment

NASA Technical Reports Server (NTRS)

Aguilar, Robert B. (Inventor); Huang, Zhaofeng (Inventor)

2012-01-01

A process includes determining a probability of a failure mode of a system being analyzed reaching a failure limit as a function of time to failure limit, determining a probability of a mitigation of the failure mode as a function of a time to failure limit, and quantifying a risk reduction based on the probability of the failure mode reaching the failure limit and the probability of the mitigation.

Potential Application of a Thermoelectric Generator in Passive Cooling System of Nuclear Power Plants

NASA Astrophysics Data System (ADS)

Wang, Dongqing; Liu, Yu; Jiang, Jin; Pang, Wei; Lau, Woon Ming; Mei, Jun

2017-05-01

In the design of nuclear power plants, various natural circulation passive cooling systems are considered to remove residual heat from the reactor core in the event of a power loss and maintain the plant's safety. These passive systems rely on gravity differences of fluids, resulting from density differentials, rather than using an external power-driven system. Unfortunately, a major drawback of such systems is their weak driving force, which can negatively impact safety. In such systems, there is a temperature difference between the heat source and the heat sink, which potentially offers a natural platform for thermoelectric generator (TEG) applications. While a previous study designed and analyzed a TEG-based passive core cooling system, this paper considers TEG applications in other passive cooling systems of nuclear power plants, after which the concept of a TEG-based passive cooling system is proposed. In such a system, electricity is produced using the system's temperature differences through the TEG, and this electricity is used to further enhance the cooling process.

Design of short-range terahertz wave passive detecting system

NASA Astrophysics Data System (ADS)

Zhang, Chao; Lou, Guowei; Zhu, Li; Qian, Songsong; Li, Ting

2016-09-01

Based on the study of radiation and transmission characteristics on THz waveband, a short-range passive detecting system is designed. The scheme originated from microwave passive detecting system. A prototype was developed following the design of key components including antennas and a harmonic mixer. The system operated at 0.36 THz. A dual-beam Cassegrain antenna was adopted for receiving signals which radiated by object and background. Local oscillator signal was generated by frequency multiplication. Harmonic mixing is adopted for reducing local oscillator signal frequency required by half. Superheterodyne technology is employed for signal acquisition. The system implemented easily. Tests and measurements were taken, which showed that the scheme was feasible and the performance of the prototype system met the design requirements.

Passivity and Dissipativity as Design and Analysis Tools for Networked Control Systems

ERIC Educational Resources Information Center

Yu, Han

2012-01-01

In this dissertation, several control problems are studied that arise when passive or dissipative systems are interconnected and controlled over a communication network. Since communication networks can impact the systems' stability and performance, there is a need to extend the results on control of passive or dissipative systems to networked…

Passive cooling system for liquid metal cooled nuclear reactors with backup coolant flow path

DOEpatents

Hunsbedt, Anstein; Boardman, Charles E.

1993-01-01

A liquid metal cooled nuclear fission reactor plant having a passive auxiliary safety cooling system for removing residual heat resulting from fuel decay during reactor shutdown, or heat produced during a mishap. This reactor plant is enhanced by a backup or secondary passive safety cooling system which augments the primary passive auxiliary cooling system when in operation, and replaces the primary system when rendered inoperable.

Passive cooling system for nuclear reactor containment structure

DOEpatents

Gou, Perng-Fei; Wade, Gentry E.

1989-01-01

A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

Passive safety injection system using borated water

DOEpatents

Conway, Lawrence E.; Schulz, Terry L.

1993-01-01

A passive safety injection system relies on differences in water density to induce natural circulatory flow patterns which help maintain prescribed concentrations of boric acid in borated water, and prevents boron from accumulating in the reactor vessel and possibly preventing heat transfer.

London 2012 Paralympic swimming: passive drag and the classification system.

PubMed

Oh, Yim-Taek; Burkett, Brendan; Osborough, Conor; Formosa, Danielle; Payton, Carl

2013-09-01

The key difference between the Olympic and Paralympic Games is the use of classification systems within Paralympic sports to provide a fair competition for athletes with a range of physical disabilities. In 2009, the International Paralympic Committee mandated the development of new, evidence-based classification systems. This study aims to assess objectively the swimming classification system by determining the relationship between passive drag and level of swimming-specific impairment, as defined by the current swimming class. Data were collected on participants at the London 2012 Paralympic Games. The passive drag force of 113 swimmers (classes 3-14) was measured using an electro-mechanical towing device and load cell. Swimmers were towed on the surface of a swimming pool at 1.5 m/s while holding their most streamlined position. Passive drag ranged from 24.9 to 82.8 N; the normalised drag (drag/mass) ranged from 0.45 to 1.86 N/kg. Significant negative associations were found between drag and the swimming class (τ = -0.41, p < 0.01) and normalised drag and the swimming class (τ = -0.60, p < 0.01). The mean difference in drag between adjacent classes was inconsistent, ranging from 0 N (6 vs 7) to 11.9 N (5 vs 6). Reciprocal Ponderal Index (a measure of slenderness) correlated moderately with normalised drag (r(P) = -0.40, p < 0.01). Although swimmers with the lowest swimming class experienced the highest passive drag and vice versa, the inconsistent difference in mean passive drag between adjacent classes indicates that the current classification system does not always differentiate clearly between swimming groups.

Passive millimeter-wave imaging polarimeter system

NASA Astrophysics Data System (ADS)

Persons, Christopher M.; Martin, Christopher A.; Jones, Michael W.; Kolinko, Vladimir; Lovberg, John A.

2009-05-01

The Army has identified a need to rapidly identify, map, and classify natural and manmade features to aid situational awareness as well as mission and tactical planning. To address these needs, Digital Fusion and Trex Enterprises have designed a full Stokes, passive MMW imaging polarimeter that is capable of being deployed on an unmanned aerial vehicle. Results of a detailed trade study are presented, where an architecture, waveband and target platform are selected. The selected architecture is a pushbroom phased-array system, which allows the system to collect a wide fieldof- view image with minimal components and weight. W band is chosen as a trade-off between spatial resolution, weather penetration, and component availability. The trade study considers several unmanned aerial system (UAS) platforms that are capable of low-level flight and that can support the MMW antenna. The utility of the passive Stokes imager is demonstrated through W band phenomenology data collections at horizontal and vertical polarization using a variety of natural and manmade materials. The concept design is detailed, along with hardware and procedures for both radiometric and polarimetric calibration. Finally, a scaled version of the concept design is presented, which is being fabricated for an upcoming demonstration on a small, manned aircraft.

Passive coherent location system simulation and evaluation

NASA Astrophysics Data System (ADS)

Slezák, Libor; Kvasnička, Michael; Pelant, Martin; Vávra, Jiř; Plšek, Radek

2006-02-01

Passive Coherent Location (PCL) is going to be important and perspective system of passive location of non cooperative and stealth targets. It works with the sources of irradiation of opportunity. PCL is intended to be a part of mobile Air Command and Control System (ACCS) as a Deployable ACCS Component (DAC). The company ERA works on PCL system parameters verification program by complete PCL simulator development since the year 2003. The Czech DoD takes financial participation on this program. The moving targets scenario, the RCS calculation by method of moment, ground clutter scattering and signal processing method (the bottle neck of the PCL) are available up to now in simulator tool. The digital signal (DSP) processing algorithms are performed both on simulated data and on real data measured at NATO C3 Agency in their Haag experiment. The Institute of Information Theory and Automation of the Academy of Sciences of the Czech Republic takes part on the implementation of the DSP algorithms in FPGA. The paper describes the simulator and signal processing structure and results both on simulated and measured data.

Role of passive remote sensors. Sensor System Panel report

NASA Astrophysics Data System (ADS)

1982-06-01

Capabilities of present passive systems are described and the development of passive remote sensing systems for the more abundant tropospheric trace species is recommended. The combination of nadir-viewing spectrometers and solar occultation for tropospheric measurement of those gases having large stratospheric burdens is discussed. Development of a nadir-viewing instrument capable of obtaining continuous spectra in narrower bands is recommended. Gas filter radiometers for species specific measurements and development of a spectral survey instrument are discussed. Further development of aerosol retrieval algorithms, including polarization techniques, for obtaining aerosol thickness and size distributions is advised. Recommendations of specific investigations to be pursued are presented.

Role of passive remote sensors. Sensor System Panel report

NASA Technical Reports Server (NTRS)

1982-01-01

Capabilities of present passive systems are described and the development of passive remote sensing systems for the more abundant tropospheric trace species is recommended. The combination of nadir-viewing spectrometers and solar occultation for tropospheric measurement of those gases having large stratospheric burdens is discussed. Development of a nadir-viewing instrument capable of obtaining continuous spectra in narrower bands is recommended. Gas filter radiometers for species specific measurements and development of a spectral survey instrument are discussed. Further development of aerosol retrieval algorithms, including polarization techniques, for obtaining aerosol thickness and size distributions is advised. Recommendations of specific investigations to be pursued are presented.

Generic Sensor Failure Modeling for Cooperative Systems.

PubMed

Jäger, Georg; Zug, Sebastian; Casimiro, António

2018-03-20

The advent of cooperative systems entails a dynamic composition of their components. As this contrasts current, statically composed systems, new approaches for maintaining their safety are required. In that endeavor, we propose an integration step that evaluates the failure model of shared information in relation to an application's fault tolerance and thereby promises maintainability of such system's safety. However, it also poses new requirements on failure models, which are not fulfilled by state-of-the-art approaches. Consequently, this work presents a mathematically defined generic failure model as well as a processing chain for automatically extracting such failure models from empirical data. By examining data of an Sharp GP2D12 distance sensor, we show that the generic failure model not only fulfills the predefined requirements, but also models failure characteristics appropriately when compared to traditional techniques.

Active subjects of passive monitoring: responses to a passive monitoring system in low-income independent living

PubMed Central

BERRIDGE, CLARA

2016-01-01

Passive monitoring technology is beginning to be reimbursed by third-party payers in the United States of America. Given the low voluntary uptake of these technologies on the market, it is important to understand the concerns and perspectives of users, former users and non-users. In this paper, the range of ways older adults relate to passive monitoring in low-income independent-living residences is presented. This includes experiences of adoption, non-adoption, discontinuation and creative ‘misuse’. The analysis of interviews reveals three key insights. First, assumptions built into the technology about how older adults live present a problem for many users who experience unwanted disruptions and threats to their behavioural autonomy. Second, resident response is varied and challenges the dominant image of residents as passive subjects of a passive monitoring system. Third, the priorities of older adults (e.g. safety, autonomy, privacy, control, contact) are more diverse and multi-faceted than those of the housing organisation staff and family members (e.g. safety, efficiency) who drive the passive monitoring intervention. The tension between needs, desires and the daily lives of older adults and the technological solutions offered to them is made visible by their active responses, including resistance to them. This exposes the active and meaningful qualities of older adults’ decisions and practices. PMID:28239211

Passive magnetic bearing system

DOEpatents

Post, Richard F.

2014-09-02

An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

Method for passive cooling liquid metal cooled nuclear reactors, and system thereof

DOEpatents

Hunsbedt, Anstein; Busboom, Herbert J.

1991-01-01

A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel.

International Space Station Passive Thermal Control System Analysis, Top Ten Lessons-Learned

NASA Technical Reports Server (NTRS)

Iovine, John

2011-01-01

The International Space Station (ISS) has been on-orbit for over 10 years, and there have been numerous technical challenges along the way from design to assembly to on-orbit anomalies and repairs. The Passive Thermal Control System (PTCS) management team has been a key player in successfully dealing with these challenges. The PTCS team performs thermal analysis in support of design and verification, launch and assembly constraints, integration, sustaining engineering, failure response, and model validation. This analysis is a significant body of work and provides a unique opportunity to compile a wealth of real world engineering and analysis knowledge and the corresponding lessons-learned. The analysis lessons encompass the full life cycle of flight hardware from design to on-orbit performance and sustaining engineering. These lessons can provide significant insight for new projects and programs. Key areas to be presented include thermal model fidelity, verification methods, analysis uncertainty, and operations support.

A new passive radon-thoron discriminative measurement system.

PubMed

Sciocchetti, G; Sciocchetti, A; Giovannoli, P; DeFelice, P; Cardellini, F; Cotellessa, G; Pagliari, M

2010-10-01

A new passive radon-thoron discriminative measurement system has been developed for monitoring radon and thoron individually. It consists of a 'couple' of passive integrating devices with a CR39 nuclear track detector (NTD). The experimental prototype is based on the application of a new concept of NTD instrument developed at ENEA, named Alpha-PREM, acronym of piston radon exposure meter, which allows controlling the detector exposure with a patented sampling technique (Int. Eu. Pat. and US Pat.). The 'twin diffusion chambers system' was based on two A-PREM devices consisting of the standard device, named NTD-Rn, and a modified version, named NTD-Rn/Tn, which was set up to improve thoron sampling efficiency of the diffusion chamber, without changing the geometry and the start/stop function of the NTD-Rn device. Coupling devices fitted on each device allowed getting a system, which works as a double-chamber structure when deployed at the monitoring position. In this paper both technical and physical aspects are considered.

A hybrid active/passive exhaust noise control system for locomotives.

PubMed

Remington, Paul J; Knight, J Scott; Hanna, Doug; Rowley, Craig

2005-01-01

A prototype hybrid system consisting of active and passive components for controlling far-field locomotive exhaust noise has been designed, assembled, and tested on a locomotive. The system consisted of a resistive passive silencer for controlling high-frequency broadband noise and a feedforward multiple-input, multiple-output active control system for suppressing low-frequency tonal noise. The active system used ten roof-mounted bandpass speaker enclosures with 2-12-in. speakers per enclosure as actuators, eight roof-mounted electret microphones as residual sensors, and an optical tachometer that sensed locomotive engine speed as a reference sensor. The system was installed on a passenger locomotive and tested in an operating rail yard. Details of the system are described and the near-field and far-field noise reductions are compared against the design goal.

X-framework: Space system failure analysis framework

NASA Astrophysics Data System (ADS)

Newman, John Steven

Space program and space systems failures result in financial losses in the multi-hundred million dollar range every year. In addition to financial loss, space system failures may also represent the loss of opportunity, loss of critical scientific, commercial and/or national defense capabilities, as well as loss of public confidence. The need exists to improve learning and expand the scope of lessons documented and offered to the space industry project team. One of the barriers to incorporating lessons learned include the way in which space system failures are documented. Multiple classes of space system failure information are identified, ranging from "sound bite" summaries in space insurance compendia, to articles in journals, lengthy data-oriented (what happened) reports, and in some rare cases, reports that treat not only the what, but also the why. In addition there are periodically published "corporate crisis" reports, typically issued after multiple or highly visible failures that explore management roles in the failure, often within a politically oriented context. Given the general lack of consistency, it is clear that a good multi-level space system/program failure framework with analytical and predictive capability is needed. This research effort set out to develop such a model. The X-Framework (x-fw) is proposed as an innovative forensic failure analysis approach, providing a multi-level understanding of the space system failure event beginning with the proximate cause, extending to the directly related work or operational processes and upward through successive management layers. The x-fw focus is on capability and control at the process level and examines: (1) management accountability and control, (2) resource and requirement allocation, and (3) planning, analysis, and risk management at each level of management. The x-fw model provides an innovative failure analysis approach for acquiring a multi-level perspective, direct and indirect causation of

Sizing criteria for a low footprint passive mine water treatment system.

PubMed

Sapsford, D J; Williams, K P

2009-02-01

The objective of this paper is to present data from a novel vertical flow mine water treatment system, demonstrate how these data can be used to generate sizing formulae for this technology, and present a comparison between the size of system based on these formulae and those of conventionally designed passive systems. The paper focuses on passive treatment of circum-neutral ferruginous mine waters bearing up to 50 mgl(-1) of iron in either ferrous or ferric form. The Vertical Flow Reactor (VFR) operates by passing mine water down through an accreting bed of ochre, the ochre bed being responsible for the intensification of iron removal by self-filtration and/or autocatalytic iron oxidation and precipitation. Key to the design and operation of the VFR system is the decrease in permeability in this ochre bed over time. The paper demonstrates that the VFR system can remove iron at many times the 10 g/m2/day removal rate - an often employed figure for the sizing of aerobic settling ponds and wetlands. The paper demonstrates that VFRs are viable and novel passive treatment system for mine waters with a smaller footprint than conventional systems.

Passive containment cooling system

DOEpatents

Billig, P.F.; Cooke, F.E.; Fitch, J.R.

1994-01-25

A passive containment cooling system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel and is vented to the drywell. An isolation pool is disposed above the GDCS pool and includes an isolation condenser therein. The condenser has an inlet line disposed in flow communication with the drywell for receiving the non-condensable gas along with any steam released therein following a loss-of-coolant accident (LOCA). The condenser also has an outlet line disposed in flow communication with the drywell for returning to the drywell both liquid condensate produced upon cooling of the steam and the non-condensable gas for reducing pressure within the containment vessel following the LOCA. 1 figure.

Passive containment cooling system

DOEpatents

Billig, Paul F.; Cooke, Franklin E.; Fitch, James R.

1994-01-01

A passive containment cooling system includes a containment vessel surrounding a reactor pressure vessel and defining a drywell therein containing a non-condensable gas. An enclosed wetwell pool is disposed inside the containment vessel, and a gravity driven cooling system (GDCS) pool is disposed above the wetwell pool in the containment vessel and is vented to the drywell. An isolation pool is disposed above the GDCS pool and includes an isolation condenser therein. The condenser has an inlet line disposed in flow communication with the drywell for receiving the non-condensable gas along with any steam released therein following a loss-of-coolant accident (LOCA). The condenser also has an outlet line disposed in flow communication with the drywell for returning to the drywell both liquid condensate produced upon cooling of the steam and the non-condensable gas for reducing pressure within the containment vessel following the LOCA.

Active-passive vibration absorber of beam-cart-seesaw system with piezoelectric transducers

NASA Astrophysics Data System (ADS)

Lin, J.; Huang, C. J.; Chang, Julian; Wang, S.-W.

2010-09-01

In contrast with fully controllable systems, a super articulated mechanical system (SAMS) is a controlled underactuated mechanical system in which the dimensions of the configuration space exceed the dimensions of the control input space. The objectives of the research are to develop a novel SAMS model which is called beam-cart-seesaw system, and renovate a novel approach for achieving a high performance active-passive piezoelectric vibration absorber for such system. The system consists of two mobile carts, which are coupled via rack and pinion mechanics to two parallel tracks mounted on pneumatic rodless cylinders. One cart carries an elastic beam, and the other cart acts as a counterbalance. One adjustable counterweight mass is also installed underneath the seesaw to serve as a passive damping mechanism to absorb impact and shock energy. The motion and control of a Bernoulli-Euler beam subjected to the modified cart/seesaw system are analyzed first. Moreover, gray relational grade is utilized to investigate the sensitivity of tuning the active proportional-integral-derivative (PID) controller to achieve desired vibration suppression performance. Consequently, it is shown that the active-passive vibration absorber can not only provide passive damping, but can also enhance the active action authority. The proposed software/hardware platform can also be profitable for the standardization of laboratory equipment, as well as for the development of entertainment tools.

Development of a portable passive-acoustic bedload monitoring system

USDA-ARS?s Scientific Manuscript database

A hydrophone-based passive acoustic bedload-monitoring system was designed, tested and deployed by researchers at the University of Mississippi and the National Sedimentation Laboratory in Oxford, MS. The hydrophone system was designed to be easily deployed and operated by non-experts. In addition, ...

Active-passive hybrid piezoelectric actuators for high-precision hard disk drive servo systems

NASA Astrophysics Data System (ADS)

Chan, Kwong Wah; Liao, Wei-Hsin

2006-03-01

Positioning precision is crucial to today's increasingly high-speed, high-capacity, high data density, and miniaturized hard disk drives (HDDs). The demand for higher bandwidth servo systems that can quickly and precisely position the read/write head on a high track density becomes more pressing. Recently, the idea of applying dual-stage actuators to track servo systems has been studied. The push-pull piezoelectric actuated devices have been developed as micro actuators for fine and fast positioning, while the voice coil motor functions as a large but coarse seeking. However, the current dual-stage actuator design uses piezoelectric patches only without passive damping. In this paper, we propose a dual-stage servo system using enhanced active-passive hybrid piezoelectric actuators. The proposed actuators will improve the existing dual-stage actuators for higher precision and shock resistance, due to the incorporation of passive damping in the design. We aim to develop this hybrid servo system not only to increase speed of track seeking but also to improve precision of track following servos in HDDs. New piezoelectrically actuated suspensions with passive damping have been designed and fabricated. In order to evaluate positioning and track following performances for the dual-stage track servo systems, experimental efforts are carried out to implement the synthesized active-passive suspension structure with enhanced piezoelectric actuators using a composite nonlinear feedback controller.

Multi-channel, passive, short-range anti-aircraft defence system

NASA Astrophysics Data System (ADS)

Gapiński, Daniel; Krzysztofik, Izabela; Koruba, Zbigniew

2018-01-01

The paper presents a novel method for tracking several air targets simultaneously. The developed concept concerns a multi-channel, passive, short-range anti-aircraft defence system based on the programmed selection of air targets and an algorithm of simultaneous synchronisation of several modified optical scanning seekers. The above system is supposed to facilitate simultaneous firing of several self-guided infrared rocket missiles at many different air targets. From the available information, it appears that, currently, there are no passive self-guided seekers that fulfil such tasks. This paper contains theoretical discussions and simulations of simultaneous detection and tracking of many air targets by mutually integrated seekers of several rocket missiles. The results of computer simulation research have been presented in a graphical form.

Generic Sensor Failure Modeling for Cooperative Systems

PubMed Central

Jäger, Georg; Zug, Sebastian

2018-01-01

The advent of cooperative systems entails a dynamic composition of their components. As this contrasts current, statically composed systems, new approaches for maintaining their safety are required. In that endeavor, we propose an integration step that evaluates the failure model of shared information in relation to an application’s fault tolerance and thereby promises maintainability of such system’s safety. However, it also poses new requirements on failure models, which are not fulfilled by state-of-the-art approaches. Consequently, this work presents a mathematically defined generic failure model as well as a processing chain for automatically extracting such failure models from empirical data. By examining data of an Sharp GP2D12 distance sensor, we show that the generic failure model not only fulfills the predefined requirements, but also models failure characteristics appropriately when compared to traditional techniques. PMID:29558435

Study on development of active-passive rehabilitation system for upper limbs: Hybrid-PLEMO

NASA Astrophysics Data System (ADS)

Kikuchi, T.; Jin, Y.; Fukushima, K.; Akai, H.; Furusho, J.

2009-02-01

In recent years, many researchers have studied the potential of using robotics technology to assist and quantify the motor functions for neuron-rehabilitation. Some kinds of haptic devices have been developed and evaluated its efficiency with clinical tests, for example, upper limb training for patients with spasticity after stroke. Active-type (motor-driven) haptic devices can realize a lot of varieties of haptics. But they basically require high-cost safety system. On the other hand, passive-type (brake-based) haptic devices have inherent safety. However, the passive robot system has strong limitation on varieties of haptics. There are not sufficient evidences to clarify how the passive/active haptics effect to the rehabilitation of motor skills. In this paper, we developed an active-passive-switchable rehabilitation system with ER clutch/brake device named "Hybrid-PLEMO" in order to address these problems. In this paper, basic structures and haptic control methods of the Hybrid-PLEMO are described.

Impact of Passive Safety on FHR Instrumentation Systems Design and Classification

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

Holcomb, David Eugene

2015-01-01

Fluoride salt-cooled high-temperature reactors (FHRs) will rely more extensively on passive safety than earlier reactor classes. 10CFR50 Appendix A, General Design Criteria for Nuclear Power Plants, establishes minimum design requirements to provide reasonable assurance of adequate safety. 10CFR50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors, provides guidance on how the safety significance of systems, structures, and components (SSCs) should be reflected in their regulatory treatment. The Nuclear Energy Institute (NEI) has provided 10 CFR 50.69 SSC Categorization Guideline (NEI-00-04) that factors in probabilistic risk assessment (PRA) model insights, as well as deterministic insights, throughmore » an integrated decision-making panel. Employing the PRA to inform deterministic requirements enables an appropriately balanced, technically sound categorization to be established. No FHR currently has an adequate PRA or set of design basis accidents to enable establishing the safety classification of its SSCs. While all SSCs used to comply with the general design criteria (GDCs) will be safety related, the intent is to limit the instrumentation risk significance through effective design and reliance on inherent passive safety characteristics. For example, FHRs have no safety-significant temperature threshold phenomena, thus enabling the primary and reserve reactivity control systems required by GDC 26 to be passively, thermally triggered at temperatures well below those for which core or primary coolant boundary damage would occur. Moreover, the passive thermal triggering of the primary and reserve shutdown systems may relegate the control rod drive motors to the control system, substantially decreasing the amount of safety-significant wiring needed. Similarly, FHR decay heat removal systems are intended to be running continuously to minimize the amount of safety-significant instrumentation needed to

Reliability Analysis of Systems Subject to First-Passage Failure

NASA Technical Reports Server (NTRS)

Lutes, Loren D.; Sarkani, Shahram

2009-01-01

An obvious goal of reliability analysis is the avoidance of system failure. However, it is generally recognized that it is often not feasible to design a practical or useful system for which failure is impossible. Thus it is necessary to use techniques that estimate the likelihood of failure based on modeling the uncertainty about such items as the demands on and capacities of various elements in the system. This usually involves the use of probability theory, and a design is considered acceptable if it has a sufficiently small probability of failure. This report contains findings of analyses of systems subject to first-passage failure.

Forewarning of Failure in Complex Systems

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

Abercrombie, Robert K; Hively, Lee M; Prowell, Stacy J

2011-01-01

As the critical infrastructures of the United States have become more and more dependent on public and private networks, the potential for widespread national impact resulting from disruption or failure of these networks has also increased. Securing the nation s critical infrastructures requires protecting not only their physical systems but, just as important, the cyber portions of the systems on which they rely. A failure is inclusive of random events, design flaws, and instabilities caused by cyber (and/or physical) attack. One such domain is failure in critical equipment. A second is aging bridges. We discuss the workings of such amore » system in the context of the necessary sensors, command and control and data collection as well as the cyber security efforts that would support this system. Their application and the implications of this computing architecture are also discussed, with respect to our nation s aging infrastructure.« less

Development of chip passivated monolithic complementary MISFET circuits with beam leads

NASA Technical Reports Server (NTRS)

Ragonese, L. J.; Kim, M. J.; Corrie, B. L.; Brouillette, J. W.; Warr, R. E.

1972-01-01

The results are presented of a program to demonstrate the processes for fabricating complementary MISFET beam-leaded circuits, which, potentially, are comparable in quality to available bipolar beam-lead chips that use silicon nitride passivation in conjunction with a platinum-titanium-gold metal system. Materials and techniques, different from the bipolar case, were used in order to be more compatible with the special requirements of fully passivated complementary MISFET devices. Two types of circuits were designed and fabricated, a D-flip-flop and a three-input NOR/NAND gate. Fifty beam-leaded chips of each type were constructed. A quality and reliability assurance program was performed to identify failure mechanisms. Sample tests and inspections (including destructive) were developed to measure the physical characteristics of the circuits.

LWIR passive perception system for stealthy unmanned ground vehicle night operations

NASA Astrophysics Data System (ADS)

Lee, Daren; Rankin, Arturo; Huertas, Andres; Nash, Jeremy; Ahuja, Gaurav; Matthies, Larry

2016-05-01

Resupplying forward-deployed units in rugged terrain in the presence of hostile forces creates a high threat to manned air and ground vehicles. An autonomous unmanned ground vehicle (UGV) capable of navigating stealthily at night in off-road and on-road terrain could significantly increase the safety and success rate of such resupply missions for warfighters. Passive night-time perception of terrain and obstacle features is a vital requirement for such missions. As part of the ONR 30 Autonomy Team, the Jet Propulsion Laboratory developed a passive, low-cost night-time perception system under the ONR Expeditionary Maneuver Warfare and Combating Terrorism Applied Research program. Using a stereo pair of forward looking LWIR uncooled microbolometer cameras, the perception system generates disparity maps using a local window-based stereo correlator to achieve real-time performance while maintaining low power consumption. To overcome the lower signal-to-noise ratio and spatial resolution of LWIR thermal imaging technologies, a series of pre-filters were applied to the input images to increase the image contrast and stereo correlator enhancements were applied to increase the disparity density. To overcome false positives generated by mixed pixels, noisy disparities from repeated textures, and uncertainty in far range measurements, a series of consistency, multi-resolution, and temporal based post-filters were employed to improve the fidelity of the output range measurements. The stereo processing leverages multi-core processors and runs under the Robot Operating System (ROS). The night-time passive perception system was tested and evaluated on fully autonomous testbed ground vehicles at SPAWAR Systems Center Pacific (SSC Pacific) and Marine Corps Base Camp Pendleton, California. This paper describes the challenges, techniques, and experimental results of developing a passive, low-cost perception system for night-time autonomous navigation.

Development of an adaptive failure detection and identification system for detecting aircraft control element failures

NASA Technical Reports Server (NTRS)

Bundick, W. Thomas

1990-01-01

A methodology for designing a failure detection and identification (FDI) system to detect and isolate control element failures in aircraft control systems is reviewed. An FDI system design for a modified B-737 aircraft resulting from this methodology is also reviewed, and the results of evaluating this system via simulation are presented. The FDI system performed well in a no-turbulence environment, but it experienced an unacceptable number of false alarms in atmospheric turbulence. An adaptive FDI system, which adjusts thresholds and other system parameters based on the estimated turbulence level, was developed and evaluated. The adaptive system performed well over all turbulence levels simulated, reliably detecting all but the smallest magnitude partially-missing-surface failures.

Spacecraft Parachute Recovery System Testing from a Failure Rate Perspective

NASA Technical Reports Server (NTRS)

Stewart, Christine E.

2013-01-01

Spacecraft parachute recovery systems, especially those with a parachute cluster, require testing to identify and reduce failures. This is especially important when the spacecraft in question is human-rated. Due to the recent effort to make spaceflight affordable, the importance of determining a minimum requirement for testing has increased. The number of tests required to achieve a mature design, with a relatively constant failure rate, can be estimated from a review of previous complex spacecraft recovery systems. Examination of the Apollo parachute testing and the Shuttle Solid Rocket Booster recovery chute system operation will clarify at which point in those programs the system reached maturity. This examination will also clarify the risks inherent in not performing a sufficient number of tests prior to operation with humans on-board. When looking at complex parachute systems used in spaceflight landing systems, a pattern begins to emerge regarding the need for a minimum amount of testing required to wring out the failure modes and reduce the failure rate of the parachute system to an acceptable level for human spaceflight. Not only a sufficient number of system level testing, but also the ability to update the design as failure modes are found is required to drive the failure rate of the system down to an acceptable level. In addition, sufficient data and images are necessary to identify incipient failure modes or to identify failure causes when a system failure occurs. In order to demonstrate the need for sufficient system level testing prior to an acceptable failure rate, the Apollo Earth Landing System (ELS) test program and the Shuttle Solid Rocket Booster Recovery System failure history will be examined, as well as some experiences in the Orion Capsule Parachute Assembly System will be noted.

Natural circulating passive cooling system for nuclear reactor containment structure

DOEpatents

Gou, Perng-Fei; Wade, Gentry E.

1990-01-01

A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

Adaptive fuzzy control of a class of nonaffine nonlinear system with input saturation based on passivity theorem.

PubMed

Molavi, Ali; Jalali, Aliakbar; Ghasemi Naraghi, Mahdi

2017-07-01

In this paper, based on the passivity theorem, an adaptive fuzzy controller is designed for a class of unknown nonaffine nonlinear systems with arbitrary relative degree and saturation input nonlinearity to track the desired trajectory. The system equations are in normal form and its unforced dynamic may be unstable. As relative degree one is a structural obstacle in system passivation approach, in this paper, backstepping method is used to circumvent this obstacle and passivate the system step by step. Because of the existence of uncertainty and disturbance in the system, exact passivation and reference tracking cannot be tackled, so the approximate passivation or passivation with respect to a set is obtained to hold the tracking error in a neighborhood around zero. Furthermore, in order to overcome the non-smoothness of the saturation input nonlinearity, a parametric smooth nonlinear function with arbitrary approximation error is used to approximate the input saturation. Finally, the simulation results for the theoretical and practical examples are given to validate the proposed controller. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

A Methodology for Modeling Nuclear Power Plant Passive Component Aging in Probabilistic Risk Assessment under the Impact of Operating Conditions, Surveillance and Maintenance Activities

NASA Astrophysics Data System (ADS)

Guler Yigitoglu, Askin

In the context of long operation of nuclear power plants (NPPs) (i.e., 60-80 years, and beyond), investigation of the aging of passive systems, structures and components (SSCs) is important to assess safety margins and to decide on reactor life extension as indicated within the U.S. Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) Program. In the traditional probabilistic risk assessment (PRA) methodology, evaluating the potential significance of aging of passive SSCs on plant risk is challenging. Although passive SSC failure rates can be added as initiating event frequencies or basic event failure rates in the traditional event-tree/fault-tree methodology, these failure rates are generally based on generic plant failure data which means that the true state of a specific plant is not reflected in a realistic manner on aging effects. Dynamic PRA methodologies have gained attention recently due to their capability to account for the plant state and thus address the difficulties in the traditional PRA modeling of aging effects of passive components using physics-based models (and also in the modeling of digital instrumentation and control systems). Physics-based models can capture the impact of complex aging processes (e.g., fatigue, stress corrosion cracking, flow-accelerated corrosion, etc.) on SSCs and can be utilized to estimate passive SSC failure rates using realistic NPP data from reactor simulation, as well as considering effects of surveillance and maintenance activities. The objectives of this dissertation are twofold: The development of a methodology for the incorporation of aging modeling of passive SSC into a reactor simulation environment to provide a framework for evaluation of their risk contribution in both the dynamic and traditional PRA; and the demonstration of the methodology through its application to pressurizer surge line pipe weld and steam generator tubes in commercial nuclear power plants. In the proposed methodology, a

Passive injection control for microfluidic systems

DOEpatents

Paul, Phillip H.; Arnold, Don W.; Neyer, David W.

2004-12-21

Apparatus for eliminating siphoning, "dead" regions, and fluid concentration gradients in microscale analytical devices. In its most basic embodiment, the present invention affords passive injection control for both electric field-driven and pressure-driven systems by providing additional fluid flow channels or auxiliary channels disposed on either side of a sample separation column. The auxiliary channels are sized such that volumetric fluid flow rate through these channels, while sufficient to move the sample away from the sample injection region in a timely fashion, is less than that through the sample separation channel or chromatograph.

Antenna array geometry optimization for a passive coherent localisation system

NASA Astrophysics Data System (ADS)

Knott, Peter; Kuschel, Heiner; O'Hagan, Daniel

2012-11-01

Passive Coherent Localisation (PCL), also known as Passive Radar, making use of RF sources of opportunity such as Radio or TV Broadcasting Stations, Cellular Phone Network Base Stations, etc. is an advancing technology for covert operation because no active radar transmitter is required. It is also an attractive addition to existing active radar stations because it has the potential to discover low-flying and low-observable targets. The CORA (Covert Radar) experimental passive radar system currently developed at Fraunhofer-FHR features a multi-channel digital radar receiver and a circular antenna array with separate elements for the VHF- and the UHF-range and is used to exploit alternatively Digital Audio (DAB) or Video Broadcasting (DVB-T) signals. For an extension of the system, a wideband antenna array is being designed for which a new discone antenna element has been developed covering the full DVB-T frequency range. The present paper describes the outline of the system and the numerical modelling and optimisation methods applied to solve the complex task of antenna array design: Electromagnetic full wave analysis is required for the parametric design of the antenna elements while combinatorial optimization methods are applied to find the best array positions and excitation coefficients for a regular omni-directional antenna performance. The different steps are combined in an iterative loop until the optimum array layout is found. Simulation and experimental results for the current system will be shown.

Tropospheric Passive Remote Sensing

NASA Technical Reports Server (NTRS)

Keafer, L. S., Jr. (Editor)

1982-01-01

The long term role of airborne/spaceborne passive remote sensing systems for tropospheric air quality research and the identification of technology advances required to improve the performance of passive remote sensing systems were discussed.

Valve system incorporating single failure protection logic

DOEpatents

Ryan, Rodger; Timmerman, Walter J. H.

1980-01-01

A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.

Impact of Active Control on Passive Safety Response Characteristics of Sodium-cooled Fast Reactors: I - Theoretical background

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

Passerini, Stefano; Ponciroli, Roberto; Vilim, Richard B.

Here, the interaction of the active control system with passive safety behavior is investigated for sodium-cooled fast reactors. A claim often made of advanced reactors is that they are passively safe against unprotected upset events. In practice, such upset events are not analyzed in the context of the plant control system, but rather the analyses are performed without considering the normally programmed response of the control system (open-loop approach). This represents an oversimplification of the safety case. The issue of passive safety override arises since the control system commands actuators whose motions have safety consequences. Depending on the upset involvingmore » the control system ( operator error, active control system failure, or inadvertent control system override), an actuator does not necessarily go in the same direction as needed for safety. So neglecting to account for control system action during an unprotected upset is nonconservative from a safety standpoint. It is important then, during the design of the plant, to consider the potential for the control system to work against the inherent and safe regulating effects of purposefully engineered temperature feedbacks.« less

Impact of Active Control on Passive Safety Response Characteristics of Sodium-cooled Fast Reactors: I - Theoretical background

DOE PAGES

Passerini, Stefano; Ponciroli, Roberto; Vilim, Richard B.

2017-06-21

Here, the interaction of the active control system with passive safety behavior is investigated for sodium-cooled fast reactors. A claim often made of advanced reactors is that they are passively safe against unprotected upset events. In practice, such upset events are not analyzed in the context of the plant control system, but rather the analyses are performed without considering the normally programmed response of the control system (open-loop approach). This represents an oversimplification of the safety case. The issue of passive safety override arises since the control system commands actuators whose motions have safety consequences. Depending on the upset involvingmore » the control system ( operator error, active control system failure, or inadvertent control system override), an actuator does not necessarily go in the same direction as needed for safety. So neglecting to account for control system action during an unprotected upset is nonconservative from a safety standpoint. It is important then, during the design of the plant, to consider the potential for the control system to work against the inherent and safe regulating effects of purposefully engineered temperature feedbacks.« less

System for Anomaly and Failure Detection (SAFD) system development

NASA Technical Reports Server (NTRS)

Oreilly, D.

1992-01-01

This task specified developing the hardware and software necessary to implement the System for Anomaly and Failure Detection (SAFD) algorithm, developed under Technology Test Bed (TTB) Task 21, on the TTB engine stand. This effort involved building two units; one unit to be installed in the Block II Space Shuttle Main Engine (SSME) Hardware Simulation Lab (HSL) at Marshall Space Flight Center (MSFC), and one unit to be installed at the TTB engine stand. Rocketdyne personnel from the HSL performed the task. The SAFD algorithm was developed as an improvement over the current redline system used in the Space Shuttle Main Engine Controller (SSMEC). Simulation tests and execution against previous hot fire tests demonstrated that the SAFD algorithm can detect engine failure as much as tens of seconds before the redline system recognized the failure. Although the current algorithm only operates during steady state conditions (engine not throttling), work is underway to expand the algorithm to work during transient condition.

Passive environmental temperature control system

DOEpatents

Corliss, John M.; Stickford, George H.

1981-01-01

Passive environmental heating and cooling systems are described, which utilize heat pipes to transmit heat to or from a thermal reservoir. In a solar heating system, a heat pipe is utilized to carry heat from a solar heat absorber plate that receives sunlight, through a thermal insulation barrier, to a heat storage wall, with the outer end of the pipe which is in contact with the solar absorber being lower than the inner end. The inclining of the heat pipe assures that the portion of working fluid, such as Freon, which is in a liquid phase will fall by gravity to the outer end of the pipe, thereby assuring diode action that prevents the reverse transfer of heat from the reservoir to the outside on cool nights. In a cooling system, the outer end of the pipe which connects to a heat dissipator, is higher than the inner end that is coupled to a cold reservoir, to allow heat transfer only out of the reservoir to the heat dissipator, and not in the reverse direction.

A structured analysis of in vitro failure loads and failure modes of fiber, metal, and ceramic post-and-core systems.

PubMed

Fokkinga, Wietske A; Kreulen, Cees M; Vallittu, Pekka K; Creugers, Nico H J

2004-01-01

This study sought to aggregate literature data on in vitro failure loads and failure modes of prefabricated fiber-reinforced composite (FRC) post systems and to compare them to those of prefabricated metal, custom-cast, and ceramic post systems. The literature was searched using MEDLINE from 1984 to 2003 for dental articles in English. Keywords used were (post or core or buildup or dowel) and (teeth or tooth). Additional inclusion/exclusion steps were conducted, each step by two independent readers: (1) Abstracts describing post-and-core techniques to reconstruct endodontically treated teeth and their mechanical and physical characteristics were included (descriptive studies or reviews were excluded); (2) articles that included FRC post systems were selected; (3) in vitro studies, single-rooted human teeth, prefabricated FRC posts, and composite as the core material were the selection criteria; and (4) failure loads and modes were extracted from the selected papers, and failure modes were dichotomized (distinction was made between "favorable failures," defined as reparable failures, and "unfavorable failures,"defined as irreparable [root] fractures). The literature search revealed 1,984 abstracts. Included were 244, 42, and 12 articles in the first, second, and third selection steps, respectively. Custom-cast post systems showed higher failure loads than prefabricated FRC post systems, whereas ceramic showed lower failure loads. Significantly more favorable failures occurred with prefabricated FRC post systems than with prefabricated and custom-cast metal post systems. The variable "post system" had a significant effect on mean failure loads. FRC post systems more frequently showed favorable failure modes than did metal post systems.

Complex Failure Forewarning System - DHS Conference Proceedings

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

Abercrombie, Robert K; Hively, Lee M; Prowell, Stacy J

2011-01-01

As the critical infrastructures of the United States have become more and more dependent on public and private networks, the potential for widespread national impact resulting from disruption or failure of these networks has also increased. Securing the nation s critical infrastructures requires protecting not only their physical systems but, just as important, the cyber portions of the systems on which they rely. A failure is inclusive of random events, design flaws, and instabilities caused by cyber (and/or physical) attack. One such domain, aging bridges, is used to explain the Complex Structure Failure Forewarning System. We discuss the workings ofmore » such a system in the context of the necessary sensors, command and control and data collection as well as the cyber security efforts that would support this system. Their application and the implications of this computing architecture are also discussed, with respect to our nation s aging infrastructure.« less

Failure analysis and modeling of a VAXcluster system

NASA Technical Reports Server (NTRS)

Tang, Dong; Iyer, Ravishankar K.; Subramani, Sujatha S.

1990-01-01

This paper discusses the results of a measurement-based analysis of real error data collected from a DEC VAXcluster multicomputer system. In addition to evaluating basic system dependability characteristics such as error and failure distributions and hazard rates for both individual machines and for the VAXcluster, reward models were developed to analyze the impact of failures on the system as a whole. The results show that more than 46 percent of all failures were due to errors in shared resources. This is despite the fact that these errors have a recovery probability greater than 0.99. The hazard rate calculations show that not only errors, but also failures occur in bursts. Approximately 40 percent of all failures occur in bursts and involved multiple machines. This result indicates that correlated failures are significant. Analysis of rewards shows that software errors have the lowest reward (0.05 vs 0.74 for disk errors). The expected reward rate (reliability measure) of the VAXcluster drops to 0.5 in 18 hours for the 7-out-of-7 model and in 80 days for the 3-out-of-7 model.

Experimental active and passive dosimetry systems for the NASA Skylab program

NASA Technical Reports Server (NTRS)

Schneider, M. F.; Janni, J. F.; Ainsworth, G. C.

1972-01-01

Active and passive dosimetry instrumentation to measure absorbed dose, charged particle spectra, and linear energy transfer spectra inside the command module and orbital workshop on the Skylab program were developed and tested. The active dosimetry system consists of one integral unit employing both a tissue equivalent ionization chamber and silicon solid state detectors. The instrument measures dose rates from 0.2 millirad/hour to 25 rads/hour, linear energy transfer spectra from 2.8 to 42.4 Kev/micron, and the proton and alpha particle energy spectra from 0.5 to 75 Mev. The active dosimeter is equipped with a portable radiation sensor for use in astronaut on-body and spacecraft shielding surveys during passage of the Skylab through significant space radiations. Data are transmitted in real time or are recorded by onboard spacecraft tape recorder for rapid evaluation of the radiation levels. The passive dosimetry systems consist of twelve (12) hard-mounted assemblies, each containing a variety of passive radiation sensors which are recoverable at the end of the mission for analysis.

New PANDA Tests to Investigate Effects of Light Gases on Passive Safety Systems

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

Paladino, D.; Auban, O.; Candreia, P.

The large- scale thermal-hydraulic PANDA facility (located at PSI in Switzerland), has been used over the last few years for investigating different passive decay- heat removal systems and containment phenomena for the next generation of light water reactors (Simplified Boiling Water Reactor: SBWR; European Simplified Boiling Water Reactor: ESBWR; Siedewasserreaktor: SWR-1000). Currently, as part of the European Commission 5. EURATOM Framework Programme project 'Testing and Enhanced Modelling of Passive Evolutionary Systems Technology for Containment Cooling' (TEMPEST), a new series of tests is being planned in the PANDA facility to experimentally investigate the distribution of non-condensable gases inside the containment andmore » their effect on the performance of the 'Passive Containment Cooling System' (PCCS). Hydrogen release caused by the metal-water reaction in the case of a postulated severe accident will be simulated in PANDA by injecting helium into the reactor pressure vessel. In order to provide suitable data for Computational Fluid Dynamic (CFD) code assessment and improvement, the instrumentation in PANDA has been upgraded for the new tests. In the present paper, a detailed discussion is given of the new PANDA tests to be performed to investigate the effects of light gas on passive safety systems. The tests are scheduled for the first half of the year 2002. (authors)« less

Experimental investigation of passive thermodynamic vent system (TVS) with liquid nitrogen

NASA Astrophysics Data System (ADS)

Bae, Junhyuk; Yoo, Junghyun; Jin, Lingxue; Jeong, Sangkwon

2018-01-01

Thermodynamic vent system (TVS) is an attractive technology to maintain an allowable pressure level of a cryogenic propellant storage in a spacecraft under micro-gravity condition. There are two types of TVS; active or passive. In this paper, the passive TVS which does not utilize a cryogenic liquid circulation pump is experimentally investigated with liquid nitrogen and numerically analyzed by thermodynamic and heat transfer model. A cylindrical copper tank, which is 198 mm in inner diameter and 216 mm in height, is utilized to suppress a thermal-stratification effect of inside cryogenic fluid. A coil heat exchanger, which is 3 m in length and 6.35 mm in outer diameter, and a fixed size orifice of which diameter is 0.4 mm are fabricated to remove heat from the stored fluid to the vented flow. Each vent process is initiated at 140 kPa and ended at 120 kPa with liquid nitrogen fill levels which are 30%, 50% and 70%, respectively. In the numerical model, the fluid in the tank is assumed to be homogeneous saturated liquid-vapor. Mass and energy balance equations with heat transfer conditions suggested in this research are considered to calculate the transient pressure variation in the tank and the amount of heat transfer across the heat exchanger. We achieve the average heat rejection rate of more than 9 W by TVS and conclude that the passive TVS operates satisfactorily. In addition, the prediction model is verified by experimental results. Although the model has limitation in providing accurate results, it can surely predict the tendency of pressure and temperature changes in the tank. Furthermore, the model can suggest how we can improve the heat exchanger design to enhance an overall efficiency of passive TVS. Moreover, the performance of passive TVS is compared with other cryogenic vent systems (direct vent system and active TVS) by suggested performance indicator.

Passive Wireless Hermetic Environment Monitoring System for Spray Painting Workshop

PubMed Central

Wang, Lifeng; Ma, Jingjing; Huang, Yan; Tang, Dan; Huang, Qing-An

2016-01-01

Passive wireless sensors have the advantages of operating without a power supply and remote sensing capability. Hence, they are very suitable for some harsh environments, such as hermetic environments, rotating parts, or very high temperature environments. The spray painting workshop is such a harsh environment, containing a large amount of flammable paint mist and organic gas. Aiming at this special environment of spray painting workshop, a passive wireless hermetic environment monitoring system was designed, fabricated, and demonstrated. The proposed system is composed of a transponder and a reader, and the circuit design of each part is given in detail in this paper. The power and the data transmission between the transponder and the reader are realized by the inductive coupling mechanism. Utilizing the back scatter modulation and channel multiplexing, the frequency signals generated by three different environmental sensors—together with their interfaces in the transponder—are wirelessly read out by the reader. Because of the harsh environment of the spray painting room, the package of the monitoring system is quite important. Three different kinds of filter films for the system package were compared. The experimental results show that the composite filter film aluminum anodic oxide/polytetrafluoroethylene (AAO/PTFE) has the best performance. After fabrication, the measured temperature, humidity, and pressure sensitivities were measured and found to be 180 Hz/°C in the range of 0~60 °C, 100 Hz/%RH in the range of 15~95 %RH, and 42 Hz/hPa in the range of 600~1100 hPa, respectively. Additionally, the remote sensing distance of the monitoring system reaches 4 cm. Finally, the passive wireless hermetic environment monitoring system was installed on the glass wall of the spray painting workshop and was successfully demonstrated. PMID:27490546

Recent Advances In Structural Vibration And Failure Mode Control In Mainland China: Theory, Experiments And Applications

NASA Astrophysics Data System (ADS)

Li, Hui; Ou, Jinping

2008-07-01

A number of researchers have been focused on structural vibration control in the past three decades over the world and fruit achievements have been made. This paper introduces the recent advances in structural vibration control including passive, active and semiactive control in mainland China. Additionally, the co-author extends the structural vibration control to failure mode control. The research on the failure mode control is also involved in this paper. For passive control, this paper introduces full scale tests of buckling-restrained braces conducted to investigate the performance of the dampers and the second-editor of the Code of Seismic Design for Buildings. For active control, this paper introduces the HMD system for wind-induced vibration control of the Guangzhou TV tower. For semiactive control, the smart damping devices, algorithms for semi-active control, design methods and applications of semi-active control for structures are introduced in this paper. The failure mode control for bridges is also introduced.

System and method of DPF passive enhancement through powertrain torque-speed management

DOEpatents

Sujan, Vivek A.; Frazier, Timothy R.

2015-11-24

This disclosure provides a method and system for determining recommendations for vehicle operation that reduce soot production in view of a diesel particulate filter (DPF) of an exhaust aftertreatment system. Recommendations generated can reduce excessive particulate matter (PM) production during transient engine events and provide for operating conditions favorable for passive regeneration. In this way, less frequent active regeneration of the DPF is needed and/or more opportunities are provided for passive regeneration. The system and method can utilize location and terrain information to anticipate and project a window of operation in view of reducing soot production and soot loading of the DPF, or provide the operator with instruction when such opportunities are present or will soon be encountered.

Pyrotechnic system failures: Causes and prevention

NASA Technical Reports Server (NTRS)

Bement, Laurence J.

1988-01-01

Although pyrotechnics have successfully accomplished many critical mechanical spacecraft functions, such as ignition, severance, jettisoning and valving (excluding propulsion), failures continue to occur. Provided is a listing of 84 failures of pyrotechnic hardware with completed design over a 23-year period, compiled informally by experts from every NASA Center, as well as the Air Force Space Division and the Naval Surface Warfare Center. Analyses are presented as to when and where these failures occurred, their technical source or cause, followed by the reasons why and how these kinds of failures persist. The major contributor is a fundamental lack of understanding of the functional mechanisms of pyrotechnic devices and systems, followed by not recognizing pyrotechnics as an engineering technology, insufficient manpower with hands-on experience, too few test facilities, and inadequate guidelines and specifications for design, development, qualification and acceptance. Recommendations are made on both a managerial and technical basis to prevent failures, increase reliability, improve existing and future designs, and develop the technology to meet future requirements.

Measurement and Analysis of Failures in Computer Systems

NASA Technical Reports Server (NTRS)

Thakur, Anshuman

1997-01-01

This thesis presents a study of software failures spanning several different releases of Tandem's NonStop-UX operating system running on Tandem Integrity S2(TMR) systems. NonStop-UX is based on UNIX System V and is fully compliant with industry standards, such as the X/Open Portability Guide, the IEEE POSIX standards, and the System V Interface Definition (SVID) extensions. In addition to providing a general UNIX interface to the hardware, the operating system has built-in recovery mechanisms and audit routines that check the consistency of the kernel data structures. The analysis is based on data on software failures and repairs collected from Tandem's product report (TPR) logs for a period exceeding three years. A TPR log is created when a customer or an internal developer observes a failure in a Tandem Integrity system. This study concentrates primarily on those TPRs that report a UNIX panic that subsequently crashes the system. Approximately 200 of the TPRs fall into this category. Approximately 50% of the failures reported are from field systems, and the rest are from the testing and development sites. It has been observed by Tandem developers that fewer cases are encountered from the field than from the test centers. Thus, the data selection mechanism has introduced a slight skew.

Adaptive-passive vibration control systems for industrial applications

NASA Astrophysics Data System (ADS)

Mayer, D.; Pfeiffer, T.; Vrbata, J.; Melz, T.

2015-04-01

Tuned vibration absorbers have become common for passive vibration reduction in many industrial applications. Lightly damped absorbers (also called neutralizers) can be used to suppress narrowband disturbances by tuning them to the excitation frequency. If the resonance is adapted in-operation, the performance of those devices can be significantly enhanced, or inertial mass can be decreased. However, the integration of actuators, sensors and control electronics into the system raises new design challenges. In this work, the development of adaptive-passive systems for vibration reduction at an industrial scale is presented. As an example, vibration reduction of a ship engine was studied in a full scale test. Simulations were used to study the feasibility and evaluate the system concept at an early stage. Several ways to adjust the resonance of the neutralizer were evaluated, including piezoelectric actuation and common mechatronic drives. Prototypes were implemented and tested. Since vibration absorbers suffer from high dynamic loads, reliability tests were used to assess the long-term behavior under operational conditions and to improve the components. It was proved that the adaptive systems are capable to withstand the mechanical loads in an industrial application. Also a control strategy had to be implemented in order to track the excitation frequency. The most mature concepts were integrated into the full scale test. An imbalance exciter was used to simulate the engine vibrations at a realistic level experimentally. The neutralizers were tested at varying excitation frequencies to evaluate the tracking capabilities of the control system. It was proved that a significant vibration reduction is possible.

Operation of passive membrane systems for drinking water treatment.

PubMed

Oka, P A; Khadem, N; Bérubé, P R

2017-05-15

The widespread adoption of submerged hollow fibre ultrafiltration (UF) for drinking water treatment is currently hindered by the complexity and cost of these membrane systems, especially in small/remote communities. Most of the complexity is associated with auxiliary fouling control measures, which include backwashing, air sparging and chemical cleaning. Recent studies have demonstrated that sustained operation without fouling control measures is possible, but little is known regarding the conditions under which extended operation can be sustained with minimal to no fouling control measures. The present study investigated the contribution of different auxiliary fouling control measures to the permeability that can be sustained, with the intent of minimizing the mechanical and operational complexity of submerged hollow fiber UF membrane systems while maximizing their throughput capacity. Sustained conditions could be achieved without backwashing, air sparging or chemical cleaning (i.e. passive operation), indicating that these fouling control measures can be eliminated, substantially simplifying the mechanical and operational complexity of submerged hollow fiber UF systems. The adoption of hydrostatic pressure (i.e. gravity) to provide the driving force for permeation further reduced the system complexity. Approximately 50% of the organic material in the raw water was removed during treatment. The sustained passive operation and effective removal of organic material was likely due to the microbial community that established itself on the membrane surface. The permeability that could be sustained was however only approximately 20% of that which can be maintained with fouling control measures. Retaining a small amount of air sparging (i.e. a few minutes daily) and incorporating a daily 1-h relaxation (i.e. permeate flux interruption) period prior to sparging more than doubled the permeability that could be sustained. Neither the approach used to interrupt the permeate

Health information systems: failure, success and improvisation.

PubMed

Heeks, Richard

2006-02-01

The generalised assumption of health information systems (HIS) success is questioned by a few commentators in the medical informatics field. They point to widespread HIS failure. The purpose of this paper was therefore to develop a better conceptual foundation for, and practical guidance on, health information systems failure (and success). Literature and case analysis plus pilot testing of developed model. Defining HIS failure and success is complex, and the current evidence base on HIS success and failure rates was found to be weak. Nonetheless, the best current estimate is that HIS failure is an important problem. The paper therefore derives and explains the "design-reality gap" conceptual model. This is shown to be robust in explaining multiple cases of HIS success and failure, yet provides a contingency that encompasses the differences which exist in different HIS contexts. The design-reality gap model is piloted to demonstrate its value as a tool for risk assessment and mitigation on HIS projects. It also throws into question traditional, structured development methodologies, highlighting the importance of emergent change and improvisation in HIS. The design-reality gap model can be used to address the problem of HIS failure, both as a post hoc evaluative tool and as a pre hoc risk assessment and mitigation tool. It also validates a set of methods, techniques, roles and competencies needed to support the dynamic improvisations that are found to underpin cases of HIS success.

Passivity-based sliding mode control for a polytopic stochastic differential inclusion system.

PubMed

Liu, Leipo; Fu, Zhumu; Song, Xiaona

2013-11-01

Passivity-based sliding mode control for a polytopic stochastic differential inclusion (PSDI) system is considered. A control law is designed such that the reachability of sliding motion is guaranteed. Moreover, sufficient conditions for mean square asymptotic stability and passivity of sliding mode dynamics are obtained by linear matrix inequalities (LMIs). Finally, two examples are given to illustrate the effectiveness of the proposed method. © 2013 ISA. Published by ISA. All rights reserved.

Simulation of an active solar energy system integrated in a passive building in order to obtain system efficiency

NASA Astrophysics Data System (ADS)

Ceacaru, Mihai C.

2012-11-01

In this work we present a simulation of an active solar energy system. This system belongs to the first passive office building (2086 square meters) in Romania and it is used for water heating consumption. This office building was opened in February 2009 and was built based on passive house design solutions. For this simulation, we use Solar Water Heating module, which belongs to the software RETSCREEN and this simulation is done for several cities in Romania. Results obtained will be compared graphically.

A systems engineering approach to automated failure cause diagnosis in space power systems

NASA Technical Reports Server (NTRS)

Dolce, James L.; Faymon, Karl A.

1987-01-01

Automatic failure-cause diagnosis is a key element in autonomous operation of space power systems such as Space Station's. A rule-based diagnostic system has been developed for determining the cause of degraded performance. The knowledge required for such diagnosis is elicited from the system engineering process by using traditional failure analysis techniques. Symptoms, failures, causes, and detector information are represented with structured data; and diagnostic procedural knowledge is represented with rules. Detected symptoms instantiate failure modes and possible causes consistent with currently held beliefs about the likelihood of the cause. A diagnosis concludes with an explanation of the observed symptoms in terms of a chain of possible causes and subcauses.

The influence of protection system failures and preventive maintenance on protection systems in distribution systems

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

Meeuwsen, J.J.; Kling, W.L.; Ploem, W.A.G.A.

1997-01-01

Protection systems in power systems can fail either by not responding when they should (failure to operate) or by operating when they should not (false tripping). The former type of failure is particularly serious since it may result in the isolation of large sections of the network. However, the probability of a failure to operate can be reduced by carrying out preventive maintenance on protection systems. This paper describes an approach to determine the impact of preventive maintenance on protection systems on the reliability of the power supply to customers. The proposed approach is based on Markov models.

Failure Analysis in Platelet Molded Composite Systems

NASA Astrophysics Data System (ADS)

Kravchenko, Sergii G.

Long-fiber discontinuous composite systems in the form of chopped prepreg tapes provide an advanced, structural grade, molding compound allowing for fabrication of complex three-dimensional components. Understanding of process-structure-property relationship is essential for application of prerpeg platelet molded components, especially because of their possible irregular disordered heterogeneous morphology. Herein, a structure-property relationship was analyzed in the composite systems of many platelets. Regular and irregular morphologies were considered. Platelet-based systems with more ordered morphology possess superior mechanical performance. While regular morphologies allow for a careful inspection of failure mechanisms derived from the morphological characteristics, irregular morphologies are representative of the composite architectures resulting from uncontrolled deposition and molding with chopped prerpegs. Progressive failure analysis (PFA) was used to study the damaged deformation up to ultimate failure in a platelet-based composite system. Computational damage mechanics approaches were utilized to conduct the PFA. The developed computational models granted understanding of how the composite structure details, meaning the platelet geometry and system morphology (geometrical arrangement and orientation distribution of platelets), define the effective mechanical properties of a platelet-molded composite system, its stiffness, strength and variability in properties.

Current Perspectives on Systemic Hypertension in Heart Failure with Preserved Ejection Fraction.

PubMed

Tam, Marty C; Lee, Ran; Cascino, Thomas M; Konerman, Matthew C; Hummel, Scott L

2017-02-01

Heart failure with preserved ejection fraction (HFpEF) is a prevalent but incompletely understood syndrome. Traditional models of HFpEF pathophysiology revolve around systemic HTN and other causes of increased left ventricular afterload leading to left ventricular hypertrophy (LVH) and diastolic dysfunction. However, emerging models attribute the development of HFpEF to systemic proinflammatory changes secondary to common comorbidities which include HTN. Alterations in passive ventricular stiffness, ventricular-arterial coupling, peripheral microvascular function, systolic reserve, and chronotropic response occur. As a result, HFpEF is heterogeneous in nature, making it difficult to prescribe uniform therapies to all patients. Nonetheless, treating systemic HTN remains a cornerstone of HFpEF management. Antihypertensive therapies have been linked to LVH regression and improvement in diastolic dysfunction. However, to date, no therapies have definitive mortality benefit in HFpEF. Non-pharmacologic management for HTN, including dietary modification, exercise, and treating sleep disordered breathing, may provide some morbidity benefit in the HFpEF population. Future research is need to identify effective treatments, perhaps in more specific subgroups, and focus may need to shift from reducing mortality to improving exercise capacity and symptoms. Tailoring antihypertensive therapies to specific phenotypes of HFpEF may be an important component of this strategy.

Passive vs. Parachute System Architecture for Robotic Sample Return Vehicles

NASA Technical Reports Server (NTRS)

Maddock, Robert W.; Henning, Allen B.; Samareh, Jamshid A.

2016-01-01

The Multi-Mission Earth Entry Vehicle (MMEEV) is a flexible vehicle concept based on the Mars Sample Return (MSR) EEV design which can be used in the preliminary sample return mission study phase to parametrically investigate any trade space of interest to determine the best entry vehicle design approach for that particular mission concept. In addition to the trade space dimensions often considered (e.g. entry conditions, payload size and mass, vehicle size, etc.), the MMEEV trade space considers whether it might be more beneficial for the vehicle to utilize a parachute system during descent/landing or to be fully passive (i.e. not use a parachute). In order to evaluate this trade space dimension, a simplified parachute system model has been developed based on inputs such as vehicle size/mass, payload size/mass and landing requirements. This model works in conjunction with analytical approximations of a mission trade space dataset provided by the MMEEV System Analysis for Planetary EDL (M-SAPE) tool to help quantify the differences between an active (with parachute) and a passive (no parachute) vehicle concept.

Systems Biology and Biomechanical Model of Heart Failure

PubMed Central

Louridas, George E; Lourida, Katerina G

2012-01-01

Heart failure is seen as a complex disease caused by a combination of a mechanical disorder, cardiac remodeling and neurohormonal activation. To define heart failure the systems biology approach integrates genes and molecules, interprets the relationship of the molecular networks with modular functional units, and explains the interaction between mechanical dysfunction and cardiac remodeling. The biomechanical model of heart failure explains satisfactorily the progression of myocardial dysfunction and the development of clinical phenotypes. The earliest mechanical changes and stresses applied in myocardial cells and/or myocardial loss or dysfunction activate left ventricular cavity remodeling and other neurohormonal regulatory mechanisms such as early release of natriuretic peptides followed by SAS and RAAS mobilization. Eventually the neurohormonal activation and the left ventricular remodeling process are leading to clinical deterioration of heart failure towards a multi-organic damage. It is hypothesized that approaching heart failure with the methodology of systems biology we promote the elucidation of its complex pathophysiology and most probably we can invent new therapeutic strategies. PMID:22935019

Techniques for Improving Pilot Recovery from System Failures

NASA Technical Reports Server (NTRS)

Pritchett, Amy R.

2001-01-01

This project examined the application of intelligent cockpit systems to aid air transport pilots at the tasks of reacting to in-flight system failures and of planning and then following a safe four dimensional trajectory to the runway threshold during emergencies. Two studies were conducted. The first examined pilot performance with a prototype awareness/alerting system in reacting to on-board system failures. In a full-motion, high-fidelity simulator, Army helicopter pilots were asked to fly a mission during which, without warning or briefing, 14 different failures were triggered at random times. Results suggest that the amount of information pilots require from such diagnostic systems is strongly dependent on their training; for failures they are commonly trained to react to with a procedural response, they needed only an indication of which failure to follow, while for 'un-trained' failures, they benefited from more intelligent and informative systems. Pilots were also found to over-rely on the system in conditions were it provided false or mis-leading information. In the second study, a proof-of-concept system was designed suitable for helping pilots replan their flights in emergency situations for quick, safe trajectory generation. This system is described in this report, including: the use of embedded fast-time simulation to predict the trajectory defined by a series of discrete actions; the models of aircraft and pilot dynamics required by the system; and the pilot interface. Then, results of a flight simulator evaluation with airline pilots are detailed. In 6 of 72 simulator runs, pilots were not able to establish a stable flight path on localizer and glideslope, suggesting a need for cockpit aids. However, results also suggest that, to be operationally feasible, such an aid must be capable of suggesting safe trajectories to the pilot; an aid that only verified plans entered by the pilot was found to have significantly detrimental effects on performance and

Space tug propulsion system failure mode, effects and criticality analysis

NASA Technical Reports Server (NTRS)

Boyd, J. W.; Hardison, E. P.; Heard, C. B.; Orourke, J. C.; Osborne, F.; Wakefield, L. T.

1972-01-01

For purposes of the study, the propulsion system was considered as consisting of the following: (1) main engine system, (2) auxiliary propulsion system, (3) pneumatic system, (4) hydrogen feed, fill, drain and vent system, (5) oxygen feed, fill, drain and vent system, and (6) helium reentry purge system. Each component was critically examined to identify possible failure modes and the subsequent effect on mission success. Each space tug mission consists of three phases: launch to separation from shuttle, separation to redocking, and redocking to landing. The analysis considered the results of failure of a component during each phase of the mission. After the failure modes of each component were tabulated, those components whose failure would result in possible or certain loss of mission or inability to return the Tug to ground were identified as critical components and a criticality number determined for each. The criticality number of a component denotes the number of mission failures in one million missions due to the loss of that component. A total of 68 components were identified as critical with criticality numbers ranging from 1 to 2990.

Enhancing the Performance of Passive Teleoperation Systems via Cutaneous Feedback.

PubMed

Pacchierotti, Claudio; Tirmizi, Asad; Bianchini, Gianni; Prattichizzo, Domenico

2015-01-01

We introduce a novel method to improve the performance of passive teleoperation systems with force reflection. It consists of integrating kinesthetic haptic feedback provided by common grounded haptic interfaces with cutaneous haptic feedback. The proposed approach can be used on top of any time-domain control technique that ensures a stable interaction by scaling down kinesthetic feedback when this is required to satisfy stability conditions (e.g., passivity) at the expense of transparency. Performance is recovered by providing a suitable amount of cutaneous force through custom wearable cutaneous devices. The viability of the proposed approach is demonstrated through an experiment of perceived stiffness and an experiment of teleoperated needle insertion in soft tissue.

Failure Prevention of Hydraulic System Based on Oil Contamination

NASA Astrophysics Data System (ADS)

Singh, M.; Lathkar, G. S.; Basu, S. K.

2012-07-01

Oil contamination is the major source of failure and wear of hydraulic system components. As per literature survey, approximately 70 % of hydraulic system failures are caused by oil contamination. Hence, to operate the hydraulic system reliably, the hydraulic oil should be of perfect condition. This requires a proper `Contamination Management System' which involves monitoring of various parameters like oil viscosity, oil temperature, contamination level etc. A study has been carried out on vehicle mounted hydraulically operated system used for articulation of heavy article, after making the platform levelled with outrigger cylinders. It is observed that by proper monitoring of contamination level, there is considerably increase in reliability, economy in operation and long service life. This also prevents the frequent failure of hydraulic system.

Forecasting overhaul or replacement intervals based on estimated system failure intensity

NASA Astrophysics Data System (ADS)

Gannon, James M.

1994-12-01

System reliability can be expressed in terms of the pattern of failure events over time. Assuming a nonhomogeneous Poisson process and Weibull intensity function for complex repairable system failures, the degree of system deterioration can be approximated. Maximum likelihood estimators (MLE's) for the system Rate of Occurrence of Failure (ROCOF) function are presented. Evaluating the integral of the ROCOF over annual usage intervals yields the expected number of annual system failures. By associating a cost of failure with the expected number of failures, budget and program policy decisions can be made based on expected future maintenance costs. Monte Carlo simulation is used to estimate the range and the distribution of the net present value and internal rate of return of alternative cash flows based on the distributions of the cost inputs and confidence intervals of the MLE's.

Measure Guideline: Passive Vents

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

Berger, David; Neri, Robin

2016-02-05

This document addresses the use of passive vents as a source of outdoor air in multifamily buildings. The challenges associated with implementing passive vents and the factors affecting performance are outlined. A comprehensive design methodology and quantified performance metrics are provided. Two hypothetical design examples are provided to illustrate the process. This document is intended to be useful to designers, decision-makers, and contractors implementing passive ventilation strategies. It is also intended to be a resource for those responsible for setting high-performance building program requirements, especially pertaining to ventilation and outdoor air. To ensure good indoor air quality, a dedicated sourcemore » of outdoor air is an integral part of high-performance buildings. Presently, there is a lack of guidance pertaining to the design and installation of passive vents, resulting in poor system performance. This report details the criteria necessary for designing, constructing, and testing passive vent systems to enable them to provide consistent and reliable levels of ventilation air from outdoors.« less

Control of Flexible Systems in the Presence of Failures

NASA Technical Reports Server (NTRS)

Magahami, Peiman G.; Cox, David E.; Bauer, Frank H. (Technical Monitor)

2001-01-01

Control of flexible systems under degradation or failure of sensors/actuators is considered. A Linear Matrix Inequality framework is used to synthesize H(sub infinity)-based controllers, which provide good disturbance rejection while capable of tolerating real parameter uncertainties in the system model, as well as potential degradation or failure of the control system hardware. In this approach, a one-at-a-time failure scenario is considered, wherein no more than one sensor or actuator is allowed to fail at any given time. A numerical example involving control synthesis for a two-dimensional flexible system is presented to demonstrate the feasibility of the proposed approach.

Principles of passive and active cooling of mirror-based hybrid systems employing liquid metals

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

Anglart, Henryk

This paper presents principles of passive and active cooling that are suitable to mirrorbased hybrid, nuclear fission/fusion systems. It is shown that liquid metal lead-bismuth cooling of the mirror machine with 25 m height and 1.5 GW thermal power is feasible both in the active mode during the normal operation and in the passive mode after the reactor shutdown. In the active mode the achievable required pumping power can well be below 50 MW, whereas the passive mode provides enough coolant flow to keep the clad temperature below the damage limits.

Principles of passive and active cooling of mirror-based hybrid systems employing liquid metals

NASA Astrophysics Data System (ADS)

Anglart, Henryk

2012-06-01

This paper presents principles of passive and active cooling that are suitable to mirrorbased hybrid, nuclear fission/fusion systems. It is shown that liquid metal lead-bismuth cooling of the mirror machine with 25 m height and 1.5 GW thermal power is feasible both in the active mode during the normal operation and in the passive mode after the reactor shutdown. In the active mode the achievable required pumping power can well be below 50 MW, whereas the passive mode provides enough coolant flow to keep the clad temperature below the damage limits.

Spacecraft dynamics characterization and control system failure detection. Volume 3: Control system failure monitoring

NASA Technical Reports Server (NTRS)

Vanschalkwyk, Christiaan M.

1992-01-01

We discuss the application of Generalized Parity Relations to two experimental flexible space structures, the NASA Langley Mini-Mast and Marshall Space Flight Center ACES mast. We concentrate on the generation of residuals and make no attempt to implement the Decision Function. It should be clear from the examples that are presented whether it would be possible to detect the failure of a specific component. We derive the equations from Generalized Parity Relations. Two special cases are treated: namely, Single Sensor Parity Relations (SSPR) and Double Sensor Parity Relations (DSPR). Generalized Parity Relations for actuators are also derived. The NASA Langley Mini-Mast and the application of SSPR and DSPR to a set of displacement sensors located at the tip of the Mini-Mast are discussed. The performance of a reduced order model that includes the first five models of the mast is compared to a set of parity relations that was identified on a set of input-output data. Both time domain and frequency domain comparisons are made. The effect of the sampling period and model order on the performance of the Residual Generators are also discussed. Failure detection experiments where the sensor set consisted of two gyros and an accelerometer are presented. The effects of model order and sampling frequency are again illustrated. The detection of actuator failures is discussed. We use Generalized Parity Relations to monitor control system component failures on the ACES mast. An overview is given of the Failure Detection Filter and experimental results are discussed. Conclusions and directions for future research are given.

Long-term performance of the passive thermal control systems of the IRAS spacecraft

NASA Technical Reports Server (NTRS)

Mason, P. V.

1988-01-01

Degradation of passive thermal control systems in space is a matter of serious concern and has been observed in many missions. The performance of the passive thermal control systems of the Infrared Astronomical Satellite (IRAS) over a period of three years is reported here. An exterior temperature of 200 K and a sunshade temperature of approximately 100 K were maintained over this period without significant degradation. The temperature of the telescope contained in the IRAS cryostat was also observed for two years after expenditure of the helium cryogen. It remained at 100 K with no degradation.

Veggie Passive Orbital Nutrient Delivery System (PONDS)

NASA Image and Video Library

2018-02-27

Project scientists, place seeds in Veggie Passive Orbital Nutrient Delivery System (PONDS) units inside a laboratory at the Space Station Processing Facility at NASA’s Kennedy Space Center in Florida. Veggie PONDS is a direct follow-on to the Veg-01 and Veg-03 hardware and plant growth validation tests. The primary goal of this newly developed plant growing system, Veggie PONDS, is to demonstrate uniform plant growth. PONDS units have features that are designed to mitigate microgravity effects on water distribution, increase oxygen exchange and provide sufficient room for root zone growth. PONDS is planned for use during Veg-04 and Veg-05 on the International Space Station after the Veggie PONDS Validation flights on SpaceX-14 and OA-9.

Automatic patient respiration failure detection system with wireless transmission

NASA Technical Reports Server (NTRS)

Dimeff, J.; Pope, J. M.

1968-01-01

Automatic respiration failure detection system detects respiration failure in patients with a surgically implanted tracheostomy tube, and actuates an audible and/or visual alarm. The system incorporates a miniature radio transmitter so that the patient is unencumbered by wires yet can be monitored from a remote location.

Hybrid Active-Passive Systems for Control of Aircraft Interior Noise

NASA Technical Reports Server (NTRS)

Fuller, Chris R.

1999-01-01

Previous work has demonstrated the large potential for hybrid active-passive systems for attenuating interior noise in aircraft fuselages. The main advantage of an active-passive system is, by utilizing the natural dynamics of the actuator system, the control actuator power and weight is markedly reduced and stability/robustness is enhanced. Three different active-passive approaches were studied in the past year. The first technique utilizes multiple tunable vibration absorbers (ATVA) for reducing narrow band sound radiated from panels and transmitted through fuselage structures. The focus is on reducing interior noise due to propeller or turbo fan harmonic excitation. Two types of tunable vibration absorbers were investigated; a solid state system based upon a piezoelectric mechanical exciter and an electromechanical system based upon a Motran shaker. Both of these systems utilize a mass-spring dynamic effect to maximize tile output force near resonance of the shaker system and so can also be used as vibration absorbers. The dynamic properties of the absorbers (i.e. resonance frequency) were modified using a feedback signal from an accelerometer mounted on the active mass, passed through a compensator and fed into the drive component of the shaker system (piezoelectric element or voice coil respectively). The feedback loop consisted of a two coefficient FIR filter, implemented on a DSP, where the input is acceleration of tile ATVA mass and the output is a force acting in parallel with the stiffness of the absorber. By separating the feedback signal into real and imaginary components, the effective natural frequency and damping of the ATVA can be altered independently. This approach gave control of the resonance frequencies while also allowing the simultaneous removal of damping from the ATVA, thus increasing the ease of controllability and effectiveness. In order to obtain a "tuned" vibration absorber the chosen resonant frequency was set to the excitation

Risk measures for power failures in transmission systems

NASA Astrophysics Data System (ADS)

Cassidy, Alex; Feinstein, Zachary; Nehorai, Arye

2016-11-01

We present a novel framework for evaluating the risk of failures in power transmission systems. We use the concept of systemic risk measures from the financial mathematics literature with models of power system failures in order to quantify the risk of the entire power system for design and comparative purposes. The proposed risk measures provide the collection of capacity vectors for the components in the system that lead to acceptable outcomes. Keys to the formulation of our measures of risk are two elements: a model of system behavior that provides the (distribution of) outcomes based on component capacities and an acceptability criterion that determines whether a (random) outcome is acceptable from an aggregated point of view. We examine the effects of altering the line capacities on energy not served under a variety of networks, flow manipulation methods, load shedding schemes, and load profiles using Monte Carlo simulations. Our results provide a quantitative comparison of the performance of these schemes, measured by the required line capacity. These results provide more complete descriptions of the risks of power failures than the previous, one-dimensional metrics.

Passive control of a biventricular assist device with compliant inflow cannulae.

PubMed

Gregory, Shaun David; Pearcy, Mark John; Timms, Daniel

2012-08-01

Rotary ventricular assist device (VAD) support of the cardiovascular system is susceptible to suction events due to the limited preload sensitivity of these devices. This may be of particular concern with rotary biventricular support (BiVAD) where the native, flow balancing Starling response is diminished in both ventricles. The reliability of sensor and sensorless-based control systems which aim to control VAD flow based on preload has limitations, and, thus, an alternative solution is desired. This study introduces a compliant inflow cannula (CIC) which could improve the preload sensitivity of a rotary VAD by passively altering VAD flow depending on preload. To evaluate the design, both the CIC and a standard rigid inflow cannula were inserted into a mock circulation loop to enable biventricular heart failure support using configurations of atrial and ventricular inflow, and arterial outflow cannulation. A range of left (LVAD) and right VAD (RVAD) rotational speeds were tested as well as step changes in systemic/pulmonary vascular resistance to alter relative preloads, with resulting flow rates recorded. Simulated suction events were observed, particularly at higher VAD speeds, during support with the rigid inflow cannula, while the CIC prevented suction events under all circumstances. The compliant section passively restricted its internal diameter as preload was reduced, which increased the VAD circuit resistance and thus reduced VAD flow. Therefore, a CIC could potentially be used as a passive control system to prevent suction events in rotary left, right, and biventricular support. © 2012, Copyright the Authors. Artificial Organs © 2012, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

49 CFR 214.529 - In-service failure of primary braking system.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false In-service failure of primary braking system. 214... Maintenance Machines and Hi-Rail Vehicles § 214.529 In-service failure of primary braking system. (a) In the event of a total in-service failure of its primary braking system, an on-track roadway maintenance...

49 CFR 214.529 - In-service failure of primary braking system.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 4 2013-10-01 2013-10-01 false In-service failure of primary braking system. 214... Maintenance Machines and Hi-Rail Vehicles § 214.529 In-service failure of primary braking system. (a) In the event of a total in-service failure of its primary braking system, an on-track roadway maintenance...

49 CFR 214.529 - In-service failure of primary braking system.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Maintenance Machines and Hi-Rail Vehicles § 214.529 In-service failure of primary braking system. (a) In the event of a total in-service failure of its primary braking system, an on-track roadway maintenance... 49 Transportation 4 2010-10-01 2010-10-01 false In-service failure of primary braking system. 214...

Failure Detecting Method of Fault Current Limiter System with Rectifier

NASA Astrophysics Data System (ADS)

Tokuda, Noriaki; Matsubara, Yoshio; Asano, Masakuni; Ohkuma, Takeshi; Sato, Yoshibumi; Takahashi, Yoshihisa

A fault current limiter (FCL) is extensively needed to suppress fault current, particularly required for trunk power systems connecting high-voltage transmission lines, such as 500kV class power system which constitutes the nucleus of the electric power system. We proposed a new type FCL system (rectifier type FCL), consisting of solid-state diodes, DC reactor and bypass AC reactor, and demonstrated the excellent performances of this FCL by developing the small 6.6kV and 66kV model. It is important to detect the failure of power devices used in the rectifier under the normal operating condition, for keeping the excellent reliability of the power system. In this paper, we have proposed a new failure detecting method of power devices most suitable for the rectifier type FCL. This failure detecting system is simple and compact. We have adapted the proposed system to the 66kV prototype single-phase model and successfully demonstrated to detect the failure of power devices.

Designing and Implementation of a Heart Failure Telemonitoring System.

PubMed

Safdari, Reza; Jafarpour, Maryam; Mokhtaran, Mehrshad; Naderi, Nasim

2017-09-01

The aim of this study was to identify patients at-risk, enhancing self-care management of HF patients at home and reduce the disease exacerbations and readmissions. In this research according to standard heart failure guidelines and Semi-structured interviews with 10 heart failure Specialists, a draft heart failure rule set for alerts and patient instructions was developed. Eventually, the clinical champion of the project vetted the rule set. Also we designed a transactional system to enhance monitoring and follow up of CHF patients. With this system, CHF patients are required to measure their physiological measurements (vital signs and body weight) every day and to submit their symptoms using the app. additionally, based on their data, they will receive customized notifications and motivation messages to classify risk of disease exacerbation. The architecture of system comprised of six major components: 1) a patient data collection suite including a mobile app and website; 2) Data Receiver; 3) Database; 4) a Specialists expert Panel; 5) Rule engine classifier; 6) Notifier engine. This system has implemented in Iran for the first time and we are currently in the testing phase with 10 patients to evaluate the technical performance of our system. The developed expert system generates alerts and instructions based on the patient's data and the notify engine notifies responsible nurses and physicians and sometimes patients. Detailed analysis of those results will be reported in a future report. This study is based on the design of a telemonitoring system for heart failure self-care that intents to overcome the gap that occurs when patients discharge from the hospital and tries to accurate requirement of readmission. A rule set for classifying and resulting automated alerts and patient instructions for heart failure telemonitoring was developed. It also facilitates daily communication among patients and heart failure clinicians so any deterioration in health could be

A passive RFID-based location system for personnel and asset monitoring.

PubMed

Hsiao, Rong-Shue; Kao, Chun-Hao; Chen, Tian-Xiang; Chen, Jui-Lun

2018-01-01

Typical radio frequency identification (RFID) access control system can be ineffective if an unauthorized person tailgates an authorized person through an access area. To propose a system by using indoor locating and tracking techniques address this problem, which is to prevent unauthorized Alzheimer's and dementia patients from getting lost including by tailgating. To achieve accurate target location, passive RFID deployment strategy is studied and a fingerprinting based passive RFID localization algorithm is proposed. The proposed system was evaluated in a building environment to simulate the performance of access control. RFID reader was installed on ceiling near the access area and tags were stitched on both shoulders of the experiment subject's garments. The probability of the error distance within 0.3 m achieved 97% in the warning area; the location precision achieved 97% within 0.4 m in the monitoring area. The result showed that if an unauthorized person enters the restricted area, the system can initiate an alert signal accurately. Therefore, the proposed system is very suitable to be used in nursing home or hospital to prevent unauthorized personnel and assets entering/exiting a confined location.

Method of remote powering and detecting multiple UWB passive tags in an RFID system

DOEpatents

Dowla, Farid U [Castro Valley, CA; Nekoogar, Faranak [San Ramon, CA; Benzel, David M [Livermore, CA; Dallum, Gregory E [Livermore, CA; Spiridon, Alex [Palo Alto, CA

2012-05-29

A new Radio Frequency Identification (RFID), tracking, powering apparatus/system and method using coded Ultra-wideband (UWB) signaling is introduced. The proposed hardware and techniques disclosed herein utilize a plurality of passive UWB transponders in a field of an RFID-radar system. The radar system itself enables multiple passive tags to be remotely powered (activated) at about the same time frame via predetermined frequency UWB pulsed formats. Once such tags are in an activated state, an UWB radar transmits specific "interrogating codes" to put predetermined tags in an awakened status. Such predetermined tags can then communicate by a unique "response code" so as to be detected by an UWB system using radar methods.

Methodology for the Incorporation of Passive Component Aging Modeling into the RAVEN/ RELAP-7 Environment

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

Mandelli, Diego; Rabiti, Cristian; Cogliati, Joshua

2014-11-01

Passive system, structure and components (SSCs) will degrade over their operation life and this degradation may cause to reduction in the safety margins of a nuclear power plant. In traditional probabilistic risk assessment (PRA) using the event-tree/fault-tree methodology, passive SSC failure rates are generally based on generic plant failure data and the true state of a specific plant is not reflected realistically. To address aging effects of passive SSCs in the traditional PRA methodology [1] does consider physics based models that account for the operating conditions in the plant, however, [1] does not include effects of surveillance/inspection. This paper representsmore » an overall methodology for the incorporation of aging modeling of passive components into the RAVEN/RELAP-7 environment which provides a framework for performing dynamic PRA. Dynamic PRA allows consideration of both epistemic and aleatory uncertainties (including those associated with maintenance activities) in a consistent phenomenological and probabilistic framework and is often needed when there is complex process/hardware/software/firmware/ human interaction [2]. Dynamic PRA has gained attention recently due to difficulties in the traditional PRA modeling of aging effects of passive components using physics based models and also in the modeling of digital instrumentation and control systems. RAVEN (Reactor Analysis and Virtual control Environment) [3] is a software package under development at the Idaho National Laboratory (INL) as an online control logic driver and post-processing tool. It is coupled to the plant transient code RELAP-7 (Reactor Excursion and Leak Analysis Program) also currently under development at INL [3], as well as RELAP 5 [4]. The overall methodology aims to: • Address multiple aging mechanisms involving large number of components in a computational feasible manner where sequencing of events is conditioned on the physical conditions predicted in a simulation

Integrated Passive Biological Treatment System/ Mine Waste Technology Program Report #16

EPA Science Inventory

This report summarizes the results of the Mine Waste Technology Program (MWTP) Activity III, Project 16, Integrated, Passive Biological Treatment System, funded by the United States Environmental Protection Agency (EPA) and jointly administered by EPA and the United States Depar...

Mixed H∞ and passive control for linear switched systems via hybrid control approach

NASA Astrophysics Data System (ADS)

Zheng, Qunxian; Ling, Youzhu; Wei, Lisheng; Zhang, Hongbin

2018-03-01

This paper investigates the mixed H∞ and passive control problem for linear switched systems based on a hybrid control strategy. To solve this problem, first, a new performance index is proposed. This performance index can be viewed as the mixed weighted H∞ and passivity performance. Then, the hybrid controllers are used to stabilise the switched systems. The hybrid controllers consist of dynamic output-feedback controllers for every subsystem and state updating controllers at the switching instant. The design of state updating controllers not only depends on the pre-switching subsystem and the post-switching subsystem, but also depends on the measurable output signal. The hybrid controllers proposed in this paper can include some existing ones as special cases. Combine the multiple Lyapunov functions approach with the average dwell time technique, new sufficient conditions are obtained. Under the new conditions, the closed-loop linear switched systems are globally uniformly asymptotically stable with a mixed H∞ and passivity performance index. Moreover, the desired hybrid controllers can be constructed by solving a set of linear matrix inequalities. Finally, a numerical example and a practical example are given.

Passive-performance, analysis, and upgrades of a 1-ton seismic attenuation system

NASA Astrophysics Data System (ADS)

Bergmann, G.; Mow-Lowry, C. M.; Adya, V. B.; Bertolini, A.; Hanke, M. M.; Kirchhoff, R.; Köhlenbeck, S. M.; Kühn, G.; Oppermann, P.; Wanner, A.; Westphal, T.; Wöhler, J.; Wu, D. S.; Lück, H.; Strain, K. A.; Danzmann, K.

2017-03-01

The 10 m prototype facility at the Albert-Einstein-institute (AEI) in Hanover, Germany, employs three large seismic attenuation systems to reduce mechanical motion. The AEI seismic-attenuation-system (AEI-SAS) uses mechanical anti-springs in order to achieve resonance frequencies below 0.5 Hz. This system provides passive isolation from ground motion by a factor of about 400 in the horizontal direction at 4 Hz and in the vertical direction at 9 Hz. The presented isolation performance is measured under vacuum conditions using a combination of commercial and custom-made inertial sensors. Detailed analysis of this performance led to the design and implementation of tuned dampers to mitigate the effect of the unavoidable higher order modes of the system. These dampers reduce RMS motion substantially in the frequency range between 10 and 100 Hz in 6 degrees of freedom. The results presented here demonstrate that the AEI-SAS provides substantial passive isolation at all the fundamental mirror-suspension resonances.

Passive Tracking System and Method

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Ngo, Phong H. (Inventor); Chen, Henry A. (Inventor); Phan, Chau T. (Inventor); Bourgeois, Brian A. (Inventor); Dusl, Jon (Inventor); Hill, Brent W. (Inventor)

2003-01-01

Systems and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes an antenna array with three antenna elements, which preferably are patch antenna elements spaced apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol.

Passive Tracking System and Method

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Ngo, Phong H. (Inventor); Chen, Henry A. (Inventor); Phan, Chau T. (Inventor); Bourgeois, Brian A. (Inventor); Dusl, John (Inventor); Hill, Brent W. (Inventor)

2005-01-01

System and methods are disclosed for passively determining the location of a moveable transmitter utilizing a pair of phase shifts at a receiver for extracting a direction vector from a receiver to the transmitter. In a preferred embodiment, a phase difference between the transmitter and receiver is extracted utilizing a noncoherent demodulator in the receiver. The receiver includes antenna array with three antenna elements, which preferably are patch antenna elements placed apart by one-half wavelength. Three receiver channels are preferably utilized for simultaneously processing the received signal from each of the three antenna elements. Multipath transmission paths for each of the three receiver channels are indexed so that comparisons of the same multipath component are made for each of the three receiver channels. The phase difference for each received signal is determined by comparing only the magnitudes of received and stored modulation signals to determine a winning modulation symbol.

Hybrid Active/Passive Jet Engine Noise Suppression System

NASA Technical Reports Server (NTRS)

Parente, C. A.; Arcas, N.; Walker, B. E.; Hersh, A. S.; Rice, E. J.

1999-01-01

A novel adaptive segmented liner concept has been developed that employs active control elements to modify the in-duct sound field to enhance the tone-suppressing performance of passive liner elements. This could potentially allow engine designs that inherently produce more tone noise but less broadband noise, or could allow passive liner designs to more optimally address high frequency broadband noise. A proof-of-concept validation program was undertaken, consisting of the development of an adaptive segmented liner that would maximize attenuation of two radial modes in a circular or annular duct. The liner consisted of a leading active segment with dual annuli of axially spaced active Helmholtz resonators, followed by an optimized passive liner and then an array of sensing microphones. Three successively complex versions of the adaptive liner were constructed and their performances tested relative to the performance of optimized uniform passive and segmented passive liners. The salient results of the tests were: The adaptive segmented liner performed well in a high flow speed model fan inlet environment, was successfully scaled to a high sound frequency and successfully attenuated three radial modes using sensor and active resonator arrays that were designed for a two mode, lower frequency environment.

Passive magnetic bearing configurations

DOEpatents

Post, Richard F [Walnut Creek, CA

2011-01-25

A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

Failure detection and fault management techniques for flush airdata sensing systems

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.; Moes, Timothy R.; Leondes, Cornelius T.

1992-01-01

A high-angle-of-attack flush airdata sensing system was installed and flight tested on the F-18 High Alpha Research Vehicle at NASA-Dryden. This system uses a matrix of pressure orifices arranged in concentric circles on the nose of the vehicle to determine angles of attack, angles of sideslip, dynamic pressure, and static pressure as well as other airdata parameters. Results presented use an arrangement of 11 symmetrically distributed ports on the aircraft nose. Experience with this sensing system data indicates that the primary concern for real-time implementation is the detection and management of overall system and individual pressure sensor failures. The multiple port sensing system is more tolerant to small disturbances in the measured pressure data than conventional probe-based intrusive airdata systems. However, under adverse circumstances, large undetected failures in individual pressure ports can result in algorithm divergence and catastrophic failure of the entire system. How system and individual port failures may be detected using chi sq. analysis is shown. Once identified, the effects of failures are eliminated using weighted least squares.

Failure Diagnosis for the Holdup Tank System via ISFA

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

Li, Huijuan; Bragg-Sitton, Shannon; Smidts, Carol

This paper discusses the use of the integrated system failure analysis (ISFA) technique for fault diagnosis for the holdup tank system. ISFA is a simulation-based, qualitative and integrated approach used to study fault propagation in systems containing both hardware and software subsystems. The holdup tank system consists of a tank containing a fluid whose level is controlled by an inlet valve and an outlet valve. We introduce the component and functional models of the system, quantify the main parameters and simulate possible failure-propagation paths based on the fault propagation approach, ISFA. The results show that most component failures in themore » holdup tank system can be identified clearly and that ISFA is viable as a technique for fault diagnosis. Since ISFA is a qualitative technique that can be used in the very early stages of system design, this case study provides indications that it can be used early to study design aspects that relate to robustness and fault tolerance.« less

Heating without heat: Thermodynamics of passive energy filters between finite systems

NASA Astrophysics Data System (ADS)

Muñoz-Tapia, R.; Brito, R.; Parrondo, J. M. R.

2017-09-01

Passive filters allowing the exchange of particles in a narrow band of energy are currently used in microrefrigerators and energy transducers. In this Rapid Communication, we analyze their thermal properties using linear irreversible thermodynamics and kinetic theory, and discuss a striking phenomenon: the possibility of simultaneously increasing or decreasing the temperatures of two systems without any supply of energy. This occurs when the filter induces a flow of particles whose energy is between the average energies of the two systems. Here we show that this selective transfer of particles does not need the action of any sort of Maxwell demon and can be carried out by passive filters without compromising the second law of thermodynamics. This phenomenon allows us to design cycles between two reservoirs at temperatures T1

Passive Thermal Management of Foil Bearings

NASA Technical Reports Server (NTRS)

Bruckner, Robert J. (Inventor)

2015-01-01

Systems and methods for passive thermal management of foil bearing systems are disclosed herein. The flow of the hydrodynamic film across the surface of bearing compliant foils may be disrupted to provide passive cooling and to improve the performance and reliability of the foil bearing system.

Evaluation of layered and mixed passive treatment systems for acid mine drainage.

PubMed

Jeen, Sung-Wook; Mattson, Bruce

2016-11-01

Laboratory column tests for passive treatment systems for mine drainage from a waste rock storage area were conducted to evaluate suitable reactive mixture, system configuration, effects of influent water chemistry, and required residence time. Five columns containing straw, chicken manure, mushroom compost, and limestone (LS), in either layered or mixed configurations, were set up to simulate the treatment system. The results showed that all of the five columns removed metals of concern (i.e. Al, Cd, Co, Cu, Fe, Ni, and Zn) with a residence time of 15 h and greater. Reaction mechanisms responsible for the removal of metals may include sulfate reduction and subsequent sulfide precipitation, precipitation of secondary carbonates and hydroxides, co-precipitation, and sorption on organic substrates and secondary precipitates. The results suggest that the mixed systems containing organic materials and LS perform better than the layered systems, sequentially treated by organic and LS layers, due to the enhanced pH adjustment, which is beneficial to bacterial activity and precipitation of secondary minerals. The column tests provide a basis for the design of a field-scale passive treatment system, such as a reducing and alkalinity producing system or a permeable reactive barrier.

Electrostatic stabilizer for a passive magnetic bearing system

DOEpatents

Post, Richard F.

2015-11-24

Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.

Electrostatic stabilizer for a passive magnetic bearing system

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

Post, Richard F

2016-10-11

Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.

Optimization of Wireless Power Transfer Systems Enhanced by Passive Elements and Metasurfaces

NASA Astrophysics Data System (ADS)

Lang, Hans-Dieter; Sarris, Costas D.

2017-10-01

This paper presents a rigorous optimization technique for wireless power transfer (WPT) systems enhanced by passive elements, ranging from simple reflectors and intermedi- ate relays all the way to general electromagnetic guiding and focusing structures, such as metasurfaces and metamaterials. At its core is a convex semidefinite relaxation formulation of the otherwise nonconvex optimization problem, of which tightness and optimality can be confirmed by a simple test of its solutions. The resulting method is rigorous, versatile, and general -- it does not rely on any assumptions. As shown in various examples, it is able to efficiently and reliably optimize such WPT systems in order to find their physical limitations on performance, optimal operating parameters and inspect their working principles, even for a large number of active transmitters and passive elements.

Demonstration of Passive Fuel Cell Thermal Management Technology

NASA Technical Reports Server (NTRS)

Burke, Kenneth A.; Jakupca, Ian; Colozza, Anthony; Wynne, Robert; Miller, Michael; Meyer, Al; Smith, William

2012-01-01

The NASA Glenn Research Center is developing advanced passive thermal management technology to reduce the mass and improve the reliability of space fuel cell systems for the NASA Exploration program. The passive thermal management system relies on heat conduction within highly thermally conductive cooling plates to move the heat from the central portion of the cell stack out to the edges of the fuel cell stack. Using the passive approach eliminates the need for a coolant pump and other cooling loop components within the fuel cell system which reduces mass and improves overall system reliability. Previous development demonstrated the performance of suitable highly thermally conductive cooling plates and integrated heat exchanger technology to collect the heat from the cooling plates (Ref. 1). The next step in the development of this passive thermal approach was the demonstration of the control of the heat removal process and the demonstration of the passive thermal control technology in actual fuel cell stacks. Tests were run with a simulated fuel cell stack passive thermal management system outfitted with passive cooling plates, an integrated heat exchanger and two types of cooling flow control valves. The tests were run to demonstrate the controllability of the passive thermal control approach. Finally, successful demonstrations of passive thermal control technology were conducted with fuel cell stacks from two fuel cell stack vendors.

Designing and Implementation of a Heart Failure Telemonitoring System

PubMed Central

Safdari, Reza; Jafarpour, Maryam; Mokhtaran, Mehrshad; Naderi, Nasim

2017-01-01

Introduction: The aim of this study was to identify patients at-risk, enhancing self-care management of HF patients at home and reduce the disease exacerbations and readmissions. Method: In this research according to standard heart failure guidelines and Semi-structured interviews with 10 heart failure Specialists, a draft heart failure rule set for alerts and patient instructions was developed. Eventually, the clinical champion of the project vetted the rule set. Also we designed a transactional system to enhance monitoring and follow up of CHF patients. With this system, CHF patients are required to measure their physiological measurements (vital signs and body weight) every day and to submit their symptoms using the app. additionally, based on their data, they will receive customized notifications and motivation messages to classify risk of disease exacerbation. The architecture of system comprised of six major components: 1) a patient data collection suite including a mobile app and website; 2) Data Receiver; 3) Database; 4) a Specialists expert Panel; 5) Rule engine classifier; 6) Notifier engine. Results: This system has implemented in Iran for the first time and we are currently in the testing phase with 10 patients to evaluate the technical performance of our system. The developed expert system generates alerts and instructions based on the patient’s data and the notify engine notifies responsible nurses and physicians and sometimes patients. Detailed analysis of those results will be reported in a future report. Conclusion: This study is based on the design of a telemonitoring system for heart failure self-care that intents to overcome the gap that occurs when patients discharge from the hospital and tries to accurate requirement of readmission. A rule set for classifying and resulting automated alerts and patient instructions for heart failure telemonitoring was developed. It also facilitates daily communication among patients and heart failure

Lunar Module Electrical Power System Design Considerations and Failure Modes

NASA Technical Reports Server (NTRS)

Interbartolo, Michael

2009-01-01

This slide presentation reviews the design and redesign considerations of the Apollo lunar module electrical power system. Included in the work are graphics showing the lunar module power system. It describes the in-flight failures, and the lessons learned from these failures.

Passive and active vibration isolation systems using inerter

NASA Astrophysics Data System (ADS)

Alujević, N.; Čakmak, D.; Wolf, H.; Jokić, M.

2018-03-01

This paper presents a theoretical study on passive and active vibration isolation schemes using inerter elements in a two degree of freedom (DOF) mechanical system. The aim of the work is to discuss basic capabilities and limitations of the vibration control systems at hand using simple and physically transparent models. Broad frequency band dynamic excitation of the source DOF is assumed. The purpose of the isolator system is to prevent vibration transmission to the receiving DOF. The frequency averaged kinetic energy of the receiving mass is used as the metric for vibration isolation quality. It is shown that the use of inerter element in the passive vibration isolation scheme can enhance the isolation effect. In the active case, a feedback disturbance rejection scheme is considered. Here, the error signal is the receiving body absolute velocity which is directly fed to a reactive force actuator between the source and the receiving bodies. In such a scheme, the so-called subcritical vibration isolation problems exist. These problems are characterised by the uncoupled natural frequency of the receiving body larger than the uncoupled natural frequency of the source body. In subcritical vibration isolation problems, the performance of the active control is limited by poor stability margins. This is because the stable feedback gain is restricted in a narrow range between a minimum and a maximum. However, with the inclusion of an inerter in the isolator, one of the two stability margins can be opened. This enables large, theoretically unlimited negative feedback gains and large active damping of the receiving body vibration. A simple expression for the required inertance is derived.

Polymer optics for the passive infrared

NASA Astrophysics Data System (ADS)

Claytor, Richard N.

2016-10-01

An important, but largely invisible, area of polymer optics involves sensing the motion of warm objects. It can be further subdivided into optics for security, for energy conservation, and for convenience; the area has become known as optics for the passive infrared. The passive infrared is generally known as the 8 to 14 μm region of the optical spectrum. The region's roots are in the traditional infrared technology of many decades ago; there is a coincident atmospheric window, although that has little relevance to many short-range applications relevant to polymer optics. Regrettably, there is no polymer material ideally suited to the passive infrared, but one material is generally superior to other candidates. The inadequacy of this material makes the Fresnel lens important. Polymer optics for the passive infrared were first introduced in the 1970s. Patents from that period will be shown, as well as early examples. The unfamiliar names of the pioneering companies and their technical leaders will be mentioned. The 1980s and 90s brought a new and improved lens type, and rapid growth. Pigments for visible-light appearance and other reasons were introduced; one was a spectacular failure. Recent advances include faster lenses, a new groove structure, additional pigments, and lens-mirror combinations. New sensor types are also being introduced. Finally, some unique and inventive applications will be discussed.

Vapor feed direct methanol fuel cells with passive thermal-fluids management system

NASA Astrophysics Data System (ADS)

Guo, Zhen; Faghri, Amir

The present paper describes a novel technology that can be used to manage methanol and water in miniature direct methanol fuel cells (DMFCs) without the need for a complex micro-fluidics subsystem. At the core of this new technology is a unique passive fuel delivery system that allows for fuel delivery at an adjustable rate from a reservoir to the anode. Furthermore, the fuel cell is designed for both passive water management and effective carbon dioxide removal. The innovative thermal management mechanism is the key for effective operation of the fuel cell system. The vapor feed DMFC reached a power density of 16.5 mW cm -2 at current density of 60 mA cm -2. A series of fuel cell prototypes in the 0.5 W range have been successfully developed. The prototypes have demonstrated long-term stable operation, easy fuel delivery control and are scalable to larger power systems. A two-cell stack has successfully operated for 6 months with negligible degradation.

System considerations for detection and tracking of small targets using passive sensors

NASA Astrophysics Data System (ADS)

DeBell, David A.

1991-08-01

Passive sensors provide only a few discriminants to assist in threat assessment of small targets. Tracking of the small targets provides additional discriminants. This paper discusses the system considerations for tracking small targets using passive sensors, in particular EO sensors. Tracking helps establish good versus bad detections. Discussed are the requirements to be placed on the sensor system's accuracy, with respect to knowledge of the sightline direction. The detection of weak targets sets a requirement for two levels of tracking in order to reduce processor throughput. A system characteristic is the need to track all detections. For low thresholds, this can mean a heavy track burden. Therefore, thresholds must be adaptive in order not to saturate the processors. Second-level tracks must develop a range estimate in order to assess threat. Sensor platform maneuvers are required if the targets are moving. The need for accurate pointing, good stability, and a good update rate will be shown quantitatively, relating to track accuracy and track association.

Passive versus active hazard detection and avoidance systems

NASA Astrophysics Data System (ADS)

Neveu, D.; Mercier, G.; Hamel, J.-F.; Simard Bilodeau, V.; Woicke, S.; Alger, M.; Beaudette, D.

2015-06-01

Upcoming planetary exploration missions will require advanced guidance, navigation and control technologies to reach landing sites with high precision and safety. Various technologies are currently in development to meet that goal. Some technologies rely on passive sensors and benefit from the low mass and power of such solutions while others rely on active sensors and benefit from an improved robustness and accuracy. This paper presents two different hazard detection and avoidance (HDA) system design approaches. The first architecture relies only on a camera as the passive HDA sensor while the second relies, in addition, on a Lidar as the active HDA sensor. Both options use in common an innovative hazard map fusion algorithm aiming at identifying the safest landing locations. This paper presents the simulation tools and reports the closed-loop software simulation results obtained using each design option. The paper also reports the Monte Carlo simulation campaign that was used to assess the robustness of each design option. The performance of each design option is compared against each other in terms of performance criteria such as percentage of success, mean distance to nearest hazard, etc. The applicability of each design option to planetary exploration missions is also discussed.

A passive gust alleviation system for a light aircraft

NASA Technical Reports Server (NTRS)

Roesch, P.; Harlan, R. B.

1975-01-01

A passive aeromechanical gust alleviation system was examined for application to a Cessna 172. The system employs small auxiliary wings to sense changes in angle of attack and to drive the wing flaps to compensate the resulting incremental lift. The flaps also can be spring loaded to neutralize the effects of variations in dynamic pressure. Conditions for gust alleviation are developed and shown to introduce marginal stability if both vertical and horizontal gusts are compensated. Satisfactory behavior is realized if only vertical gusts are absorbed; however, elevator control is effectively negated by the system. Techniques to couple the elevator and flaps are demonstrated to restore full controllability without sacrifice of gust alleviation.

Passive Solar Heating Residences.

DTIC Science & Technology

1979-07-01

concerned, as long as the basic system falls within one of the passive concepts, then it is a passive system. If a fan can increase the system~s...wood walls and roof is R-22, in the block walls (urea-formaldahyde foam sprayed in wall cavity) is R-30, and a 4" styro- foam board at the slab edge (R...is based cn 1,000 BTU/sq. ft./day, which is a clear day value. The south windows have reflectors which will increase the energy gained (30% by Steve

Testing the Feasibility of a Passive and Active Case Ascertainment System for Multiple Rare Conditions Simultaneously: The Experience in Three US States

PubMed Central

McDermott, Suzanne; Ruttenber, Margaret; Mann, Joshua; Smith, Michael G; Royer, Julie; Valdez, Rodolfo

2016-01-01

Background Owing to their low prevalence, single rare conditions are difficult to monitor through current state passive and active case ascertainment systems. However, such monitoring is important because, as a group, rare conditions have great impact on the health of affected individuals and the well-being of their caregivers. A viable approach could be to conduct passive and active case ascertainment of several rare conditions simultaneously. This is a report about the feasibility of such an approach. Objective To test the feasibility of a case ascertainment system with passive and active components aimed at monitoring 3 rare conditions simultaneously in 3 states of the United States (Colorado, Kansas, and South Carolina). The 3 conditions are spina bifida, muscular dystrophy, and fragile X syndrome. Methods Teams from each state evaluated the possibility of using current or modified versions of their local passive and active case ascertainment systems and datasets to monitor the 3 conditions. Together, these teams established the case definitions and selected the variables and the abstraction tools for the active case ascertainment approach. After testing the ability of their local passive and active case ascertainment system to capture all 3 conditions, the next steps were to report the number of cases detected actively and passively for each condition, to list the local barriers against the combined passive and active case ascertainment system, and to describe the experiences in trying to overcome these barriers. Results During the test period, the team from South Carolina was able to collect data on all 3 conditions simultaneously for all ages. The Colorado team was also able to collect data on all 3 conditions but, because of age restrictions in its passive and active case ascertainment system, it was able to report few cases of fragile X syndrome. The team from Kansas was able to collect data only on spina bifida. For all states, the implementation of an

Passive beam forming and spatial diversity in meteor scatter communication systems

NASA Astrophysics Data System (ADS)

Akram, Ammad; Cannon, Paul S.

1996-03-01

The method of passive beam formation using a four-element Butler matrix to improve the signal availability of meteor scatter communication systems is investigated. Signal availability, defined as the integrated time that the signal-to-noise ratio (snr) exceeds some snr threshold, serves as an important indicator of system performance. Butler matrix signal availability is compared with the performance of a single four-element Yagi reference system using ˜6.5 hours of data from a 720 km north-south temperate latitude link. The signal availability improvement factor of the Butler matrix is found to range between 1.6-1.8 over the snr threshold range of 20-30 dB in a 300-Hz bandwidth. Experimental values of the Butler matrix signal availability improvement factor are compared with analytical predictions. The experimental values show an expected snr threshold dependency with a dramatic increase at high snr. A theoretical analysis is developed to describe this increase. The signal availability can be further improved by ˜10-20% in a system employing two four-element Butler matrices with squinted beams so as to illuminate the sky with eight high-gain beams. Space diversity is found to increase the signal availability of a single antenna system by ˜10-15%, but the technique has very little advantage in a system already employing passive beam formation.

A Novel Reliable WDM-PON System

NASA Astrophysics Data System (ADS)

Chen, Benyang; Gan, Chaoqin; Qi, Yongqian; Xia, Lei

2011-12-01

In this paper, a reliable Wavelength-Division-Multiplexing Passive Optical Network (WDM-PON) system is proposed. It can provide the protection against both the feeder fiber failure and the distribution fiber failure. When the fiber failure occurs, the corresponding switches in the OLT and in the ONU can switch to the protection link without affecting the users in normal status. That is to say, the protection for one ONU is independent of the other ONUs.

Low cost passive solar adobe house

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

Not Available

1981-12-21

A brief description, photographs, and cost breakdown of a hybrid direct-gain passive solar adobe house constructed in the City of El Paso, Texas. The 3-panel active solar domestic hot water system acts as a back-up to the direct gain passive system.

Use of failure modes and effects analysis in design of the tracker system for the HET wide-field upgrade

NASA Astrophysics Data System (ADS)

Hayes, Richard; Beets, Tim; Beno, Joseph; Booth, John; Cornell, Mark; Good, John; Heisler, James; Hill, Gary; Kriel, Herman; Penney, Charles; Rafal, Marc; Savage, Richard; Soukup, Ian; Worthington, Michael; Zierer, Joseph

2012-09-01

In support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), the Center for Electromechanics at The University of Texas at Austin was tasked with developing the new Tracker and control system to support the HETDEX Wide-Field Upgrade. The tracker carries the 3,100 kg Prime Focus Instrument Package and Wide Field Corrector approximately 13 m above the 10 m diameter primary mirror. Its safe and reliable operation by a sophisticated control system, over a 20 year life time is a paramount requirement for the project. To account for all potential failures and potential hazards, to both the equipment and personnel involved, an extensive Failure Modes and Effects Analysis (FMEA) was completed early in the project. This task required participation of all the stakeholders over a multi-day meeting with numerous follow up exchanges. The event drove a number of significant design decisions and requirements that might not have been identified this early in the project without this process. The result is a system that has multiple layers of active and passive safety systems to protect the tens of millions of dollars of hardware involved and the people who operate it. This paper will describe the background of the FMEA process, how it was utilized on HETDEX, the critical outcomes, how the required safety systems were implemented, and how they have worked in operation. It should be of interest to engineers, designers, and managers engaging in complex multi-disciplinary and parallel engineering projects that involve automated hardware and control systems with potentially hazardous operating scenarios.

High-throughput countercurrent microextraction in passive mode.

PubMed

Xie, Tingliang; Xu, Cong

2018-05-15

Although microextraction is much more efficient than conventional macroextraction, its practical application has been limited by low throughputs and difficulties in constructing robust countercurrent microextraction (CCME) systems. In this work, a robust CCME process was established based on a novel passive microextractor with four units without any moving parts. The passive microextractor has internal recirculation and can efficiently mix two immiscible liquids. The hydraulic characteristics as well as the extraction and back-extraction performance of the passive CCME were investigated experimentally. The recovery efficiencies of the passive CCME were 1.43-1.68 times larger than the best values achieved using cocurrent extraction. Furthermore, the total throughput of the passive CCME developed in this work was about one to three orders of magnitude higher than that of other passive CCME systems reported in the literature. Therefore, a robust CCME process with high throughputs has been successfully constructed, which may promote the application of passive CCME in a wide variety of fields.

The cognitive-behavioral system of leadership: cognitive antecedents of active and passive leadership behaviors

PubMed Central

Dóci, Edina; Stouten, Jeroen; Hofmans, Joeri

2015-01-01

In the present paper, we propose a cognitive-behavioral understanding of active and passive leadership. Building on core evaluations theory, we offer a model that explains the emergence of leaders’ active and passive behaviors, thereby predicting stable, inter-individual, as well as variable, intra-individual differences in both types of leadership behavior. We explain leaders’ stable behavioral tendencies by their fundamental beliefs about themselves, others, and the world (core evaluations), while their variable, momentary behaviors are explained by the leaders’ momentary appraisals of themselves, others, and the world (specific evaluations). By introducing interactions between the situation the leader enters, the leader’s beliefs, appraisals, and behavior, we propose a comprehensive system of cognitive mechanisms that underlie active and passive leadership behavior. PMID:26441721

Target detection using microwave irradiances from natural sources: A passive, local and global surveillance system

NASA Technical Reports Server (NTRS)

Stacey, J. M.

1984-01-01

Detection of metal objects on or near the Earth's surface was investigated using existing, passive, microwave sensors operating from Earth orbit. The range equations are derived from basic microwave principles and theories and the expressions are given explicitly to estimate the signal to noise ratio for detecting metal targets operating as bistatic scatterers. Actual measurements are made on a range of metal objects observed from orbit using existing passive microwave receiving systems. The details of the measurements and the results are tabulated and discussed. The advantages of a passive microwave sensor as it is applied to surveillance of metal objects as viewed from aerial platforms or from orbit, are examined.

Probability of loss of assured safety in systems with multiple time-dependent failure modes.

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

Helton, Jon Craig; Pilch, Martin.; Sallaberry, Cedric Jean-Marie.

2012-09-01

Weak link (WL)/strong link (SL) systems are important parts of the overall operational design of high-consequence systems. In such designs, the SL system is very robust and is intended to permit operation of the entire system under, and only under, intended conditions. In contrast, the WL system is intended to fail in a predictable and irreversible manner under accident conditions and render the entire system inoperable before an accidental operation of the SL system. The likelihood that the WL system will fail to deactivate the entire system before the SL system fails (i.e., degrades into a configuration that could allowmore » an accidental operation of the entire system) is referred to as probability of loss of assured safety (PLOAS). Representations for PLOAS for situations in which both link physical properties and link failure properties are time-dependent are derived and numerically evaluated for a variety of WL/SL configurations, including PLOAS defined by (i) failure of all SLs before failure of any WL, (ii) failure of any SL before failure of any WL, (iii) failure of all SLs before failure of all WLs, and (iv) failure of any SL before failure of all WLs. The effects of aleatory uncertainty and epistemic uncertainty in the definition and numerical evaluation of PLOAS are considered.« less

Causes of catastrophic failure in complex systems

NASA Astrophysics Data System (ADS)

Thomas, David A.

2010-08-01

Root causes of mission critical failures and major cost and schedule overruns in complex systems and programs are studied through the post-mortem analyses compiled for several examples, including the Hubble Space Telescope, the Challenger and Columbia Shuttle accidents, and the Three Mile Island nuclear power plant accident. The roles of organizational complexity, cognitive biases in decision making, the display of quantitative data, and cost and schedule pressure are all considered. Recommendations for mitigating the risk of similar failures in future programs are also provided.

Global Passivity in Microscopic Thermodynamics

NASA Astrophysics Data System (ADS)

Uzdin, Raam; Rahav, Saar

2018-04-01

The main thread that links classical thermodynamics and the thermodynamics of small quantum systems is the celebrated Clausius inequality form of the second law. However, its application to small quantum systems suffers from two cardinal problems. (i) The Clausius inequality does not hold when the system and environment are initially correlated—a commonly encountered scenario in microscopic setups. (ii) In some other cases, the Clausius inequality does not provide any useful information (e.g., in dephasing scenarios). We address these deficiencies by developing the notion of global passivity and employing it as a tool for deriving thermodynamic inequalities on observables. For initially uncorrelated thermal environments the global passivity framework recovers the Clausius inequality. More generally, global passivity provides an extension of the Clausius inequality that holds even in the presences of strong initial system-environment correlations. Crucially, the present framework provides additional thermodynamic bounds on expectation values. To illustrate the role of the additional bounds, we use them to detect unaccounted heat leaks and weak feedback operations ("Maxwell demons") that the Clausius inequality cannot detect. In addition, it is shown that global passivity can put practical upper and lower bounds on the buildup of system-environment correlations for dephasing interactions. Our findings are highly relevant for experiments in various systems such as ion traps, superconducting circuits, atoms in optical cavities, and more.

Evaluation of the performance of a passive-active vibration isolation system

NASA Astrophysics Data System (ADS)

Sun, L. L.; Hansen, C. H.; Doolan, C.

2015-01-01

The behavior of a feedforward active isolation system subjected to actuator output constraints is investigated. Distributed parameter models are developed to analyze the system response, and to produce a transfer matrix for the design of an integrated passive-active isolation system. Cost functions considered here comprise a combination of the vibration transmission energy and the sum of the squared control forces. The example system considered is a rigid body connected to a simply supported plate via two isolation mounts. The overall isolation performance is evaluated by numerical simulation. The results show that the control strategies which rely on unconstrained actuator outputs may give substantial power transmission reductions over a wide frequency range, but also require large control force amplitudes to control excited vibration modes of the system. Expected power transmission reductions for modified control strategies that incorporate constrained actuator outputs are considerably less than typical reductions with unconstrained actuator outputs. The active system with constrained control force outputs is shown to be more effective at the resonance frequencies of the supporting plate. However, in the frequency range in which rigid body modes are present, the control strategies employed using constrained actuator outputs can only achieve 5-10 dB power transmission reduction, while at off-resonance frequencies, little or no power transmission reduction can be obtained with realistic control forces. Analysis of the wave effects in the passive mounts is also presented.

Integration of active and passive cool roof system for attic temperature reduction

NASA Astrophysics Data System (ADS)

Yew, Ming Chian; Yew, Ming Kun; Saw, Lip Huat; Durairaj, Rajkumar

2017-04-01

The aim of this project is to study the capability of cool roof system in the reduction of heat transmission through metal roof into an attic. The cool roof system is designed in active and passive methods to reduce the thermal loads imposed to a building. Two main features are introduced to this cool roof system, which is thermal insulation coating (TIC) and moving air cavity (MAC) that served as active and passive manner, respectively. For MAC, two designs are introduced. Normal MAC is fabricated by six aluminium tubes whereby each aluminium tube is made up by sticking up of five aluminium cans. While improved MAC is also made by six aluminium tubes whereby each aluminium tube is custom made from steel rods and aluminium foils. MAC provides ventilation and heat reflection under the metal roof before the heat transfer into attic. It also coupled with three solar powered fans to increase heat flow inside the channel. The cool roof that incorporated TIC, MAC with solar powered fans and opened attic inlet showed a significant improvement with a reduction of up to 14 °C in the attic temperature compared to conventional roof system.

Syndromic surveillance for health information system failures: a feasibility study.

PubMed

Ong, Mei-Sing; Magrabi, Farah; Coiera, Enrico

2013-05-01

To explore the applicability of a syndromic surveillance method to the early detection of health information technology (HIT) system failures. A syndromic surveillance system was developed to monitor a laboratory information system at a tertiary hospital. Four indices were monitored: (1) total laboratory records being created; (2) total records with missing results; (3) average serum potassium results; and (4) total duplicated tests on a patient. The goal was to detect HIT system failures causing: data loss at the record level; data loss at the field level; erroneous data; and unintended duplication of data. Time-series models of the indices were constructed, and statistical process control charts were used to detect unexpected behaviors. The ability of the models to detect HIT system failures was evaluated using simulated failures, each lasting for 24 h, with error rates ranging from 1% to 35%. In detecting data loss at the record level, the model achieved a sensitivity of 0.26 when the simulated error rate was 1%, while maintaining a specificity of 0.98. Detection performance improved with increasing error rates, achieving a perfect sensitivity when the error rate was 35%. In the detection of missing results, erroneous serum potassium results and unintended repetition of tests, perfect sensitivity was attained when the error rate was as small as 5%. Decreasing the error rate to 1% resulted in a drop in sensitivity to 0.65-0.85. Syndromic surveillance methods can potentially be applied to monitor HIT systems, to facilitate the early detection of failures.

Syndromic surveillance for health information system failures: a feasibility study

PubMed Central

Ong, Mei-Sing; Magrabi, Farah; Coiera, Enrico

2013-01-01

Objective To explore the applicability of a syndromic surveillance method to the early detection of health information technology (HIT) system failures. Methods A syndromic surveillance system was developed to monitor a laboratory information system at a tertiary hospital. Four indices were monitored: (1) total laboratory records being created; (2) total records with missing results; (3) average serum potassium results; and (4) total duplicated tests on a patient. The goal was to detect HIT system failures causing: data loss at the record level; data loss at the field level; erroneous data; and unintended duplication of data. Time-series models of the indices were constructed, and statistical process control charts were used to detect unexpected behaviors. The ability of the models to detect HIT system failures was evaluated using simulated failures, each lasting for 24 h, with error rates ranging from 1% to 35%. Results In detecting data loss at the record level, the model achieved a sensitivity of 0.26 when the simulated error rate was 1%, while maintaining a specificity of 0.98. Detection performance improved with increasing error rates, achieving a perfect sensitivity when the error rate was 35%. In the detection of missing results, erroneous serum potassium results and unintended repetition of tests, perfect sensitivity was attained when the error rate was as small as 5%. Decreasing the error rate to 1% resulted in a drop in sensitivity to 0.65–0.85. Conclusions Syndromic surveillance methods can potentially be applied to monitor HIT systems, to facilitate the early detection of failures. PMID:23184193

Using Rollback Avoidance to Mitigate Failures in Next-Generation Extreme-Scale Systems

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

Levy, Scott N.

2016-05-01

High-performance computing (HPC) systems enable scientists to numerically model complex phenomena in many important physical systems. The next major milestone in the development of HPC systems is the construction of the rst supercomputer capable executing more than an exa op, 10 18 oating point operations per second. On systems of this scale, failures will occur much more frequently than on current systems. As a result, resilience is a key obstacle to building next-generation extremescale systems. Coordinated checkpointing is currently the most widely-used mechanism for handling failures on HPC systems. Although coordinated checkpointing remains e ective on current systems, increasing themore » scale of today's systems to build next-generation systems will increase the cost of fault tolerance as more and more time is taken away from the application to protect against or recover from failure. Rollback avoidance techniques seek to mitigate the cost of checkpoint/restart by allowing an application to continue its execution rather than rolling back to an earlier checkpoint when failures occur. These techniqes include failure prediction and preventive migration, replicated computation, fault-tolerant algorithms, and softwarebased memory fault correction. In this thesis, we examine how rollback avoidance techniques can be used to address failures on extreme-scale systems. Using a combination of analytic modeling and simulation, we evaluate the potential impact of rollback avoidance on these systems. We then present a novel rollback avoidance technique that exploits similarities in application memory. Finally, we examine the feasibility of using this technique to protect against memory faults in kernel memory.« less

Chip PCR. I. Surface passivation of microfabricated silicon-glass chips for PCR.

PubMed Central

Shoffner, M A; Cheng, J; Hvichia, G E; Kricka, L J; Wilding, P

1996-01-01

The microreaction volumes of PCR chips (a microfabricated silicon chip bonded to a piece of flat glass to form a PCR reaction chamber) create a relatively high surface to volume ratio that increases the significance of the surface chemistry in the polymerase chain reaction (PCR). We investigated several surface passivations in an attempt to identify 'PCR friendly' surfaces and used those surfaces to obtain amplifications comparable with those obtained in conventional PCR amplification systems using polyethylene tubes. Surface passivations by a silanization procedure followed by a coating of a selected protein or polynucleotide and the deposition of a nitride or oxide layer onto the silicon surface were investigated. Native silicon was found to be an inhibitor of PCR and amplification in an untreated PCR chip (i.e. native slicon) had a high failure rate. A silicon nitride (Si(3)N(4) reaction surface also resulted in consistent inhibition of PCR. Passivating the PCR chip using a silanizing agent followed by a polymer treatment resulted in good amplification. However, amplification yields were inconsistent and were not always comparable with PCR in a conventional tube. An oxidized silicon (SiO(2) surface gave consistent amplifications comparable with reactions performed in a conventional PCR tube. PMID:8628665

Performance evaluation of a hybrid-passive landfill leachate treatment system using multivariate statistical techniques

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

Wallace, Jack, E-mail: jack.wallace@ce.queensu.ca; Champagne, Pascale, E-mail: champagne@civil.queensu.ca; Monnier, Anne-Charlotte, E-mail: anne-charlotte.monnier@insa-lyon.fr

Highlights: • Performance of a hybrid passive landfill leachate treatment system was evaluated. • 33 Water chemistry parameters were sampled for 21 months and statistically analyzed. • Parameters were strongly linked and explained most (>40%) of the variation in data. • Alkalinity, ammonia, COD, heavy metals, and iron were criteria for performance. • Eight other parameters were key in modeling system dynamics and criteria. - Abstract: A pilot-scale hybrid-passive treatment system operated at the Merrick Landfill in North Bay, Ontario, Canada, treats municipal landfill leachate and provides for subsequent natural attenuation. Collected leachate is directed to a hybrid-passive treatment system,more » followed by controlled release to a natural attenuation zone before entering the nearby Little Sturgeon River. The study presents a comprehensive evaluation of the performance of the system using multivariate statistical techniques to determine the interactions between parameters, major pollutants in the leachate, and the biological and chemical processes occurring in the system. Five parameters (ammonia, alkalinity, chemical oxygen demand (COD), “heavy” metals of interest, with atomic weights above calcium, and iron) were set as criteria for the evaluation of system performance based on their toxicity to aquatic ecosystems and importance in treatment with respect to discharge regulations. System data for a full range of water quality parameters over a 21-month period were analyzed using principal components analysis (PCA), as well as principal components (PC) and partial least squares (PLS) regressions. PCA indicated a high degree of association for most parameters with the first PC, which explained a high percentage (>40%) of the variation in the data, suggesting strong statistical relationships among most of the parameters in the system. Regression analyses identified 8 parameters (set as independent variables) that were most frequently retained for

Passivity-based control of linear time-invariant systems modelled by bond graph

NASA Astrophysics Data System (ADS)

Galindo, R.; Ngwompo, R. F.

2018-02-01

Closed-loop control systems are designed for linear time-invariant (LTI) controllable and observable systems modelled by bond graph (BG). Cascade and feedback interconnections of BG models are realised through active bonds with no loading effect. The use of active bonds may lead to non-conservation of energy and the overall system is modelled by proposed pseudo-junction structures. These structures are build by adding parasitic elements to the BG models and the overall system may become singularly perturbed. The structures for these interconnections can be seen as consisting of inner structures that satisfy energy conservation properties and outer structures including multiport-coupled dissipative fields. These fields highlight energy properties like passivity that are useful for control design. In both interconnections, junction structures and dissipative fields for the controllers are proposed, and passivity is guaranteed for the closed-loop systems assuring robust stability. The cascade interconnection is applied to the structural representation of closed-loop transfer functions, when a stabilising controller is applied to a given nominal plant. Applications are given when the plant and the controller are described by state-space realisations. The feedback interconnection is used getting necessary and sufficient stability conditions based on the closed-loop characteristic polynomial, solving a pole-placement problem and achieving zero-stationary state error.

Local-Level Prognostics Health Management Systems Framework for Passive AdvSMR Components. Interim Report

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

Ramuhalli, Pradeep; Roy, Surajit; Hirt, Evelyn H.

2014-09-12

This report describes research results to date in support of the integration and demonstration of diagnostics technologies for prototypical AdvSMR passive components (to establish condition indices for monitoring) with model-based prognostics methods. The focus of the PHM methodology and algorithm development in this study is at the localized scale. Multiple localized measurements of material condition (using advanced nondestructive measurement methods), along with available measurements of the stressor environment, enhance the performance of localized diagnostics and prognostics of passive AdvSMR components and systems.

Interior design for passive solar homes

NASA Astrophysics Data System (ADS)

Breen, J. C.

1981-07-01

The increasing emphasis on refinement of passive solar systems brought recognition to interior design as an integral part of passive solar architecture. Interior design can be used as a finetuning tool minimizing many of the problems associated with passive solar energy use in residential buildings. In addition, treatment of interior space in solar model homes may be a prime factor in determining sales success. A new style of interior design is evolving in response to changes in building from incorporating passive solar design features. The psychology behind passive solar architecture is reflected in interiors, and selection of interior components increasingly depends on the functional suitably of various interior elements.

Agent autonomy approach to probabilistic physics-of-failure modeling of complex dynamic systems with interacting failure mechanisms

NASA Astrophysics Data System (ADS)

Gromek, Katherine Emily

A novel computational and inference framework of the physics-of-failure (PoF) reliability modeling for complex dynamic systems has been established in this research. The PoF-based reliability models are used to perform a real time simulation of system failure processes, so that the system level reliability modeling would constitute inferences from checking the status of component level reliability at any given time. The "agent autonomy" concept is applied as a solution method for the system-level probabilistic PoF-based (i.e. PPoF-based) modeling. This concept originated from artificial intelligence (AI) as a leading intelligent computational inference in modeling of multi agents systems (MAS). The concept of agent autonomy in the context of reliability modeling was first proposed by M. Azarkhail [1], where a fundamentally new idea of system representation by autonomous intelligent agents for the purpose of reliability modeling was introduced. Contribution of the current work lies in the further development of the agent anatomy concept, particularly the refined agent classification within the scope of the PoF-based system reliability modeling, new approaches to the learning and the autonomy properties of the intelligent agents, and modeling interacting failure mechanisms within the dynamic engineering system. The autonomous property of intelligent agents is defined as agent's ability to self-activate, deactivate or completely redefine their role in the analysis. This property of agents and the ability to model interacting failure mechanisms of the system elements makes the agent autonomy fundamentally different from all existing methods of probabilistic PoF-based reliability modeling. 1. Azarkhail, M., "Agent Autonomy Approach to Physics-Based Reliability Modeling of Structures and Mechanical Systems", PhD thesis, University of Maryland, College Park, 2007.

Passive, Direct-Read Monitoring System for Selective Detection and Quantification of Hydrogen Chloride

NASA Technical Reports Server (NTRS)

Chapman, K. B.; Mihaylov, G. M.; Kirollos, K. S.

2000-01-01

Monitoring the exposure of an employee to hydrogen chloride or hydrochloric acid in the presence of other acids has been a challenge to the industrial hygiene community. The capability of a device to differentiate the levels of acid vapors would allow for more accurate determinations of exposure and therefore improved occupational health. In this work, a selective direct-read colorimetric badge system was validated for Short Term Exposure Limit (STEL) monitoring of hydrogen chloride. The passive colorimetric badge system consists of a direct reading badge and a color scale. The badge has a coated indicator layer with a diffusive resistance in the shape of an exclamation mark. An exclamation mark will appear if hydrogen chloride is present in the atmosphere at concentrations at or above 2.0 ppm. By using the color scale, the intensity of the color formed on the badge can be further quantified up to 25 ppm. The system was validated according to a protocol based on the NIOSH Protocol for the Evaluation of Passive Monitors. The badge was exposed to relative humidities ranging from 11% to 92%, temperatures ranging from 7 C to 400 C and air velocities ranging from 5 cm/sec to 170 cm/sec. All experiments were conducted in a laboratory vapor generation system. Hydrofluoric acid, nitric acid, sulfuric acid, chlorine, hydrogen sulfide and organic acids showed no effect on the performance of the hydrogen chloride monitoring system. The passive badge and color scale system exceeded the accuracy requirements as defined by NIOSH. At ambient conditions, the mean coefficient of variation was 10.86 and the mean bias was 1.3%. This data was presented previously at the American Industrial Hygiene Conference and Exposition in Toronto, Canada in June 1999.

Comparison of plasma B-type natriuretic peptide levels in single ventricle patients with systemic ventricle heart failure versus isolated cavopulmonary failure.

PubMed

Law, Yuk Ming; Ettedgui, Jose; Beerman, Lee; Maisel, Alan; Tofovic, Stevan

2006-08-15

The measurement of plasma B-type natriuretic peptide (BNP) has emerged as a useful biomarker of heart failure in patients with cardiomyopathy. The pathophysiology of heart failure in single ventricle (SV) circulation may be distinct from that of cardiomyopathies. A distinct pattern of BNP elevation in heart failure in the SV population was hypothesized: it is elevated in heart failure secondary to ventricular dysfunction but not in isolated cavopulmonary failure. BNP was measured prospectively in SV patients at catheterization (n = 22) and when assessing for heart failure (n = 11) (7 normal controls). Of 33 SV subjects (median age 62 months), 13 had aortopulmonary connections and 20 had cavopulmonary connections. Median and mean +/- SD BNP levels by shunt type were 184 and 754 +/- 1,086 pg/ml in the patients with aortopulmonary connections, 38 and 169 +/- 251 pg/ml in the patients with cavopulmonary connections, and 10 and 11 +/- 5 pg/ml in normal controls, respectively (p = 0.004). Median systemic ventricular end-diastolic pressure (8mm Hg, R = 0.45), mean pulmonary artery pressure (14.5 mm Hg, R = 0.62), and mean right atrial pressure (6.5 mm Hg, R = 0.54) were correlated with plasma BNP. SV subjects with symptomatic heart failure from dysfunctional systemic ventricles had median and mean +/- SD BNP levels of 378 and 714 +/- 912 pg/ml (n = 18) compared with patients with isolated failed Glenn or Fontan connections (19 and 23 +/- 16 pg/ml [n = 7, p = 0.001]) and those with no heart failure (22 and 22 +/- 12 pg/ml [n = 8, p = 0.001]). Excluding the group with cavopulmonary failure, the severity of heart failure from systemic ventricular dysfunction was associated with plasma BNP. In conclusion, plasma BNP is elevated in SV patients with systemic ventricular or left-sided cardiac failure. BNP is not elevated in patients missing a pulmonary ventricle with isolated cavopulmonary failure.

Analysis of maxillary arch force/couple systems for a simulated high canine malocclusion: Part 1. Passive ligation.

PubMed

Fok, Jonathan; Toogood, Roger W; Badawi, Hisham; Carey, Jason P; Major, Paul W

2011-11-01

To better understand the mechanics of bracket/archwire interaction through analysis of force and couple distribution along the maxillary arch. An orthodontic simulator was utilized to study high canine malocclusion. Force/couple distributions, referenced to the center of resistance (CR) of each tooth, produced by passive ligation brackets and round wire were measured. Tests were repeated for 12 bracket sets with 12 wires per set. Propagation of the force/couple systems around the arch was minimal. Binding was observed only on the teeth adjacent to the displaced canine. For most of the teeth, reduced resistance to sliding of the passive ligation bracket yielded minimal tangential and normal forces at the bracket and contributed to lower moments at CR. Some potential mechanical advantages of passive ligation systems are suggested for the case studied. In particular, limited propagation around the arch reduces the occurrence of unwanted force/couple systems.

Seismic passive earth resistance using modified pseudo-dynamic method

NASA Astrophysics Data System (ADS)

Pain, Anindya; Choudhury, Deepankar; Bhattacharyya, S. K.

2017-04-01

In earthquake prone areas, understanding of the seismic passive earth resistance is very important for the design of different geotechnical earth retaining structures. In this study, the limit equilibrium method is used for estimation of critical seismic passive earth resistance for an inclined wall supporting horizontal cohesionless backfill. A composite failure surface is considered in the present analysis. Seismic forces are computed assuming the backfill soil as a viscoelastic material overlying a rigid stratum and the rigid stratum is subjected to a harmonic shaking. The present method satisfies the boundary conditions. The amplification of acceleration depends on the properties of the backfill soil and on the characteristics of the input motion. The acceleration distribution along the depth of the backfill is found to be nonlinear in nature. The present study shows that the horizontal and vertical acceleration distribution in the backfill soil is not always in-phase for the critical value of the seismic passive earth pressure coefficient. The effect of different parameters on the seismic passive earth pressure is studied in detail. A comparison of the present method with other theories is also presented, which shows the merits of the present study.

A Survivable Wavelength Division Multiplexing Passive Optical Network with Both Point-to-Point Service and Broadcast Service Delivery

NASA Astrophysics Data System (ADS)

Ma, Xuejiao; Gan, Chaoqin; Deng, Shiqi; Huang, Yan

2011-11-01

A survivable wavelength division multiplexing passive optical network enabling both point-to-point service and broadcast service is presented and demonstrated. This architecture provides an automatic traffic recovery against feeder and distribution fiber link failure, respectively. In addition, it also simplifies the protection design for multiple services transmission in wavelength division multiplexing passive optical networks.

Dense range map reconstruction from a versatile robotic sensor system with an active trinocular vision and a passive binocular vision.

PubMed

Kim, Min Young; Lee, Hyunkee; Cho, Hyungsuck

2008-04-10

One major research issue associated with 3D perception by robotic systems is the creation of efficient sensor systems that can generate dense range maps reliably. A visual sensor system for robotic applications is developed that is inherently equipped with two types of sensor, an active trinocular vision and a passive stereo vision. Unlike in conventional active vision systems that use a large number of images with variations of projected patterns for dense range map acquisition or from conventional passive vision systems that work well on specific environments with sufficient feature information, a cooperative bidirectional sensor fusion method for this visual sensor system enables us to acquire a reliable dense range map using active and passive information simultaneously. The fusion algorithms are composed of two parts, one in which the passive stereo vision helps active vision and the other in which the active trinocular vision helps the passive one. The first part matches the laser patterns in stereo laser images with the help of intensity images; the second part utilizes an information fusion technique using the dynamic programming method in which image regions between laser patterns are matched pixel-by-pixel with help of the fusion results obtained in the first part. To determine how the proposed sensor system and fusion algorithms can work in real applications, the sensor system is implemented on a robotic system, and the proposed algorithms are applied. A series of experimental tests is performed for a variety of configurations of robot and environments. The performance of the sensor system is discussed in detail.

Quantifying effectiveness of failure prediction and response in HPC systems : methodology and example.

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

Mayo, Jackson R.; Chen, Frank Xiaoxiao; Pebay, Philippe Pierre

2010-06-01

Effective failure prediction and mitigation strategies in high-performance computing systems could provide huge gains in resilience of tightly coupled large-scale scientific codes. These gains would come from prediction-directed process migration and resource servicing, intelligent resource allocation, and checkpointing driven by failure predictors rather than at regular intervals based on nominal mean time to failure. Given probabilistic associations of outlier behavior in hardware-related metrics with eventual failure in hardware, system software, and/or applications, this paper explores approaches for quantifying the effects of prediction and mitigation strategies and demonstrates these using actual production system data. We describe context-relevant methodologies for determining themore » accuracy and cost-benefit of predictors. While many research studies have quantified the expected impact of growing system size, and the associated shortened mean time to failure (MTTF), on application performance in large-scale high-performance computing (HPC) platforms, there has been little if any work to quantify the possible gains from predicting system resource failures with significant but imperfect accuracy. This possibly stems from HPC system complexity and the fact that, to date, no one has established any good predictors of failure in these systems. Our work in the OVIS project aims to discover these predictors via a variety of data collection techniques and statistical analysis methods that yield probabilistic predictions. The question then is, 'How good or useful are these predictions?' We investigate methods for answering this question in a general setting, and illustrate them using a specific failure predictor discovered on a production system at Sandia.« less

Passive pavement-mounted acoustical linguistic drive alert system and method

DOEpatents

Kisner, Roger A.; Anderson, Richard L.; Carnal, Charles L.; Hylton, James O.; Stevens, Samuel S.

2001-01-01

Systems and methods are described for passive pavement-mounted acoustical alert of the occupants of a vehicle. A method of notifying a vehicle occupant includes providing a driving medium upon which a vehicle is to be driven; and texturing a portion of the driving medium such that the textured portion interacts with the vehicle to produce audible signals, the textured portion pattern such that a linguistic message is encoded into the audible signals. The systems and methods provide advantages because information can be conveyed to the occupants of the vehicle based on the location of the vehicle relative to the textured surface.

An autonomous recovery mechanism against optical distribution network failures in EPON

NASA Astrophysics Data System (ADS)

Liem, Andrew Tanny; Hwang, I.-Shyan; Nikoukar, AliAkbar

2014-10-01

Ethernet Passive Optical Network (EPON) is chosen for servicing diverse applications with higher bandwidth and Quality-of-Service (QoS), starting from Fiber-To-The-Home (FTTH), FTTB (business/building) and FTTO (office). Typically, a single OLT can provide services to both residential and business customers on the same Optical Line Terminal (OLT) port; thus, any failures in the system will cause a great loss for both network operators and customers. Network operators are looking for low-cost and high service availability mechanisms that focus on the failures that occur within the drop fiber section because the majority of faults are in this particular section. Therefore, in this paper, we propose an autonomous recovery mechanism that provides protection and recovery against Drop Distribution Fiber (DDF) link faults or transceiver failure at the ONU(s) in EPON systems. In the proposed mechanism, the ONU can automatically detect any signal anomalies in the physical layer or transceiver failure, switching the working line to the protection line and sending the critical event alarm to OLT via its neighbor. Each ONU has a protection line, which is connected to the nearest neighbor ONU, and therefore, when failure occurs, the ONU can still transmit and receive data via the neighbor ONU. Lastly, the Fault Dynamic Bandwidth Allocation for recovery mechanism is presented. Simulation results show that our proposed autonomous recovery mechanism is able to maintain the overall QoS performance in terms of mean packet delay, system throughput, packet loss and EF jitter.

Design and evaluation of a failure detection and isolation algorithm for restructurable control systems

NASA Technical Reports Server (NTRS)

Weiss, Jerold L.; Hsu, John Y.

1986-01-01

The use of a decentralized approach to failure detection and isolation for use in restructurable control systems is examined. This work has produced: (1) A method for evaluating fundamental limits to FDI performance; (2) Application using flight recorded data; (3) A working control element FDI system with maximal sensitivity to critical control element failures; (4) Extensive testing on realistic simulations; and (5) A detailed design methodology involving parameter optimization (with respect to model uncertainties) and sensitivity analyses. This project has concentrated on detection and isolation of generic control element failures since these failures frequently lead to emergency conditions and since knowledge of remaining control authority is essential for control system redesign. The failures are generic in the sense that no temporal failure signature information was assumed. Thus, various forms of functional failures are treated in a unified fashion. Such a treatment results in a robust FDI system (i.e., one that covers all failure modes) but sacrifices some performance when detailed failure signature information is known, useful, and employed properly. It was assumed throughout that all sensors are validated (i.e., contain only in-spec errors) and that only the first failure of a single control element needs to be detected and isolated. The FDI system which has been developed will handle a class of multiple failures.

Triplexer Monitor Design for Failure Detection in FTTH System

NASA Astrophysics Data System (ADS)

Fu, Minglei; Le, Zichun; Hu, Jinhua; Fei, Xia

2012-09-01

Triplexer was one of the key components in FTTH systems, which employed an analog overlay channel for video broadcasting in addition to bidirectional digital transmission. To enhance the survivability of triplexer as well as the robustness of FTTH system, a multi-ports device named triplexer monitor was designed and realized, by which failures at triplexer ports can be detected and localized. Triplexer monitor was composed of integrated circuits and its four input ports were connected with the beam splitter whose power division ratio was 95∶5. By means of detecting the sampled optical signal from the beam splitters, triplexer monitor tracked the status of the four ports in triplexer (e.g. 1310 nm, 1490 nm, 1550 nm and com ports). In this paper, the operation scenario of the triplexer monitor with external optical devices was addressed. And the integrated circuit structure of the triplexer monitor was also given. Furthermore, a failure localization algorithm was proposed, which based on the state transition diagram. In order to measure the failure detection and localization time under the circumstance of different failed ports, an experimental test-bed was built. Experiment results showed that the detection time for the failure at 1310 nm port by the triplexer monitor was less than 8.20 ms. For the failure at 1490 nm or 1550 nm port it was less than 8.20 ms and for the failure at com port it was less than 7.20 ms.

Most energetic passive states.

PubMed

Perarnau-Llobet, Martí; Hovhannisyan, Karen V; Huber, Marcus; Skrzypczyk, Paul; Tura, Jordi; Acín, Antonio

2015-10-01

Passive states are defined as those states that do not allow for work extraction in a cyclic (unitary) process. Within the set of passive states, thermal states are the most stable ones: they maximize the entropy for a given energy, and similarly they minimize the energy for a given entropy. Here we find the passive states lying in the other extreme, i.e., those that maximize the energy for a given entropy, which we show also minimize the entropy when the energy is fixed. These extremal properties make these states useful to obtain fundamental bounds for the thermodynamics of finite-dimensional quantum systems, which we show in several scenarios.

10 CFR 1008.24 - Criminal penalties-failure to publish a system notice.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Criminal penalties-failure to publish a system notice...—failure to publish a system notice. Subsection (i)(2) of the Act provides that an agency officer or employee who willfully maintains a system of records without publishing a system notice as required by...

Mobile Pit verification system design based on passive special nuclear material verification in weapons storage facilities

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

Paul, J. N.; Chin, M. R.; Sjoden, G. E.

2013-07-01

A mobile 'drive by' passive radiation detection system to be applied in special nuclear materials (SNM) storage facilities for validation and compliance purposes has been designed through the use of computational modeling and new radiation detection methods. This project was the result of work over a 1 year period to create optimal design specifications to include creation of 3D models using both Monte Carlo and deterministic codes to characterize the gamma and neutron leakage out each surface of SNM-bearing canisters. Results were compared and agreement was demonstrated between both models. Container leakages were then used to determine the expected reactionmore » rates using transport theory in the detectors when placed at varying distances from the can. A 'typical' background signature was incorporated to determine the minimum signatures versus the probability of detection to evaluate moving source protocols with collimation. This established the criteria for verification of source presence and time gating at a given vehicle speed. New methods for the passive detection of SNM were employed and shown to give reliable identification of age and material for highly enriched uranium (HEU) and weapons grade plutonium (WGPu). The finalized 'Mobile Pit Verification System' (MPVS) design demonstrated that a 'drive-by' detection system, collimated and operating at nominally 2 mph, is capable of rapidly verifying each and every weapon pit stored in regularly spaced, shelved storage containers, using completely passive gamma and neutron signatures for HEU and WGPu. This system is ready for real evaluation to demonstrate passive total material accountability in storage facilities. (authors)« less

Impact of Active Control on Passive Safety Response Characteristics of Sodium-Cooled Fast Reactors: II-Model Implementation and Simulations

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

Ponciroli, Roberto; Passerini, Stefano; Vilim, Richard B.

Advanced reactors are often claimed to be passively safe against unprotected upset events. In common practice, these events are not considered in the context of the plant control system, i.e., the reactor is subjected to classes of unprotected upset events while the normally programmed response of the control system is assumed not to be present. However, this approach constitutes an oversimplification since, depending on the upset involving the control system, an actuator does not necessarily go in the same direction as needed for safety. In this work, dynamic simulations are performed to assess the degree to which the inherent self-regulatingmore » plant response is safe from active control system override. The simulations are meant to characterize the resilience of the plant to unprotected initiators. The initiators were represented and modeled as an actuator going to a hard limit. Consideration of failure is further limited to individual controllers as there is no cross-connect of signals between these controllers. The potential for passive safety override by the control system is then relegated to the single-input single-output controllers. Here, the results show that when the plant control system is designed by taking into account and quantifying the impact of the plant control system on accidental scenarios there is very limited opportunity for the preprogrammed response of the control system to override passive safety protection in the event of an unprotected initiator.« less

Impact of Active Control on Passive Safety Response Characteristics of Sodium-Cooled Fast Reactors: II-Model Implementation and Simulations

DOE PAGES

Ponciroli, Roberto; Passerini, Stefano; Vilim, Richard B.

2017-06-21

Advanced reactors are often claimed to be passively safe against unprotected upset events. In common practice, these events are not considered in the context of the plant control system, i.e., the reactor is subjected to classes of unprotected upset events while the normally programmed response of the control system is assumed not to be present. However, this approach constitutes an oversimplification since, depending on the upset involving the control system, an actuator does not necessarily go in the same direction as needed for safety. In this work, dynamic simulations are performed to assess the degree to which the inherent self-regulatingmore » plant response is safe from active control system override. The simulations are meant to characterize the resilience of the plant to unprotected initiators. The initiators were represented and modeled as an actuator going to a hard limit. Consideration of failure is further limited to individual controllers as there is no cross-connect of signals between these controllers. The potential for passive safety override by the control system is then relegated to the single-input single-output controllers. Here, the results show that when the plant control system is designed by taking into account and quantifying the impact of the plant control system on accidental scenarios there is very limited opportunity for the preprogrammed response of the control system to override passive safety protection in the event of an unprotected initiator.« less

Advanced Aerodynamic Design of Passive Porosity Control Effectors

NASA Technical Reports Server (NTRS)

Hunter, Craig A.; Viken, Sally A.; Wood, Richard M.; Bauer, Steven X. S.

2001-01-01

This paper describes aerodynamic design work aimed at developing a passive porosity control effector system for a generic tailless fighter aircraft. As part of this work, a computational design tool was developed and used to layout passive porosity effector systems for longitudinal and lateral-directional control at a low-speed, high angle of attack condition. Aerodynamic analysis was conducted using the NASA Langley computational fluid dynamics code USM3D, in conjunction with a newly formulated surface boundary condition for passive porosity. Results indicate that passive porosity effectors can provide maneuver control increments that equal and exceed those of conventional aerodynamic effectors for low-speed, high-alpha flight, with control levels that are a linear function of porous area. This work demonstrates the tremendous potential of passive porosity to yield simple control effector systems that have no external moving parts and will preserve an aircraft's fixed outer mold line.

Magnetorheological valve based actuator for improvement of passively controlled turbocharger system

NASA Astrophysics Data System (ADS)

Bahiuddin, I.; Mazlan, S. A.; Imaduddin, F.; Ubaidillah, Ichwan, B.

2016-03-01

Variable geometry turbochargers have been widely researched to fulfil the current engine stringent regulations. The passively controlled turbocharger (PCT) concept has been proposed to reduce energy consumption by utilizing the emission energy to move the actuator. However, it only covered a small range operating condition. Therefore, a magnetorheological(MR) Valve device, as typical smart material devices to enhance a passive device, is proposed to improve the PCT. Even though the benefits have been considered for the compactness and easiness to connect to an electrical system, the number of publications regarding the MR application within engine system is hard to be found. Therefore, this paper introduces a design of an MR Valve in a turbocharger. The main challenge is to make sure its capability to produce a sufficient total pressure drop. To overcome the challenge, its material properties, shape and pressure drop calculation has been analyzed to fulfil the requirement. Finally, to get a more understanding of actuator performance, the actuator response was simulated by treating the exhaust gas pressure as an input. It shows that the new MR actuator has a potential dynamic to improve the PCT controllability.

48 CFR 211.275 - Passive radio frequency identification.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Passive radio frequency identification. 211.275 Section 211.275 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS... Requirements Documents 211.275 Passive radio frequency identification. ...

Corrosion control when using passively treated abandoned mine drainage as alternative makeup water for cooling systems.

PubMed

Hsieh, Ming-Kai; Chien, Shih-Hsiang; Li, Heng; Monnell, Jason D; Dzombak, David A; Vidic, Radisav D

2011-09-01

Passively treated abandoned mine drainage (AMD) is a promising alternative to fresh water as power plant cooling water system makeup water in mining regions where such water is abundant. Passive treatment and reuse of AMD can avoid the contamination of surface water caused by discharge of abandoned mine water, which typically is acidic and contains high concentrations of metals, especially iron. The purpose of this study was to evaluate the feasibility of reusing passively treated AMD in cooling systems with respect to corrosion control through laboratory experiments and pilot-scale field testing. The results showed that, with the addition of the inhibitor mixture orthophosphate and tolyltriazole, mild steel and copper corrosion rates were reduced to acceptable levels (< 0.127 mm/y and < 0.0076 mm/y, respectively). Aluminum had pitting corrosion problems in every condition tested, while cupronickel showed that, even in the absence of any inhibitor and in the presence of the biocide monochloramine, its corrosion rate was still very low (0.018 mm/y).

To the systematization of failure analysis for perturbed systems (in German)

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

Haller, U.

1974-01-01

The paper investigates the reliable functioning of complex technical systems. Of main importance is the question of how the functioning of technical systems which may fail or whose design still has some faults can be determined in the very earliest planning stages. The present paper is to develop a functioning schedule and to look for possible methods of systematic failure analysis of systems with stochastic failures. (RW/AK)

Involvement of systemic venous congestion in heart failure.

PubMed

Rubio Gracia, J; Sánchez Marteles, M; Pérez Calvo, J I

2017-04-01

Systemic venous congestion has gained significant importance in the interpretation of the pathophysiology of acute heart failure, especially in the development of renal function impairment during exacerbations. In this study, we review the concept, clinical characterisation and identification of venous congestion. We update current knowledge on its importance in the pathophysiology of acute heart failure and its involvement in the prognosis. We pay special attention to the relationship between abdominal congestion, the pulmonary interstitium as filtering membrane, inflammatory phenomena and renal function impairment in acute heart failure. Lastly, we review decongestion as a new therapeutic objective and the measures available for its assessment. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Medicina Interna (SEMI). All rights reserved.

Assessing cellulolysis in passive treatment systems for mine drainage: a modified enzyme assay.

PubMed

McDonald, Corina M; Gould, W Douglas; Lindsay, Matthew B J; Blowes, David W; Ptacek, Carol J; Condon, Peter D

2013-01-01

A modified cellulase enzyme assay was developed to monitor organic matter degradation in passive treatment systems for mine drainage. This fluorogenic substrate method facilitates assessment of exo-(1,4)-β-D-glucanase, endo-(1,4)-β-D-glucanase, and β-glucosidase, which compose an important cellulase enzyme system. The modified method was developed and refined using samples of organic carbon-amended mine tailings from field experiments where sulfate reduction was induced as a strategy for managing water quality. Sample masses (3 g) and the number of replicates ( ≥ 3) were optimized. Matrix interferences within these metal-rich samples were found to be insignificant. Application of this modified cellulase assay method provided insight into the availability and degradation of organic carbon within the amended tailings. Results of this study indicate that cellulase enzyme assays can be applied to passive treatment systems for mine drainage, which commonly contain elevated concentrations of metals. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Evaluation of Fuzzy Rulemaking for Expert Systems for Failure Detection

NASA Technical Reports Server (NTRS)

Laritz, F.; Sheridan, T. B.

1984-01-01

Computer aids in expert systems were proposed to diagnose failures in complex systems. It is shown that the fuzzy set theory of Zadeh offers a new perspective for modeling for humans thinking and language use. It is assumed that real expert human operators of aircraft, power plants and other systems do not think of their control tasks or failure diagnosis tasks in terms of control laws in differential equation form, but rather keep in mind a set of rules of thumb in fuzzy form. Fuzzy set experiments are described.

A non-imaging polarized terahertz passive system for detecting and identifying concealed explosives

NASA Astrophysics Data System (ADS)

Karam, Mostafa A.; Meyer, Doug

2011-06-01

Existing terahertz THz systems for detecting concealed explosives are not capable of identifying explosive type which leads to higher false alarm rates. Moreover, some of those systems are imaging systems that invade personal privacy, and require more processing and computational resources. Other systems have no polarization preference which makes them incapable of capturing the geometric features of an explosive. In this study a non-imaging polarized THz passive system for detecting and identifying concealed explosives overcoming the forgoing shortcomings is developed. The system employs a polarized passive THz sensor in acquiring emitted data from a scene that may have concealed explosives. The acquired data are decomposed into their natural resonance frequencies, and the number of those frequencies is used as criteria in detecting the explosive presence. If the presence of an explosive is confirmed, a set of physically based retrieval algorithms is used in extracting the explosive dielectric constant/refractive index value from natural resonance frequencies and amplitudes of associated signals. Comparing the refractive index value against a database of refractive indexes of known explosives identifies the explosive type. As an application, a system having a dual polarized radiometer operating within the frequency band of 0.62- 0.82 THz is presented and used in detecting and identifying person borne C-4 explosive concealed under a cotton garment. The system showed higher efficiencies in detecting and identifying the explosive.

Flight test of a passive millimeter-wave imaging system

NASA Astrophysics Data System (ADS)

Martin, Christopher A.; Manning, Will; Kolinko, Vladimir G.; Hall, Max

2005-05-01

A real-time passive millimeter-wave imaging system with a wide-field of view and 3K temperature sensitivity is described. The system was flown on a UH-1H helicopter in a flight test conducted by the U.S. Army RDECOM CERDEC Night Vision and Electronic Sensors Directorate (NVESD). We collected approximately eight hours of data over the course of the two-week flight test. Flight data was collected in horizontal and vertical polarizations at look down angles from 0 to 40 degrees. Speeds varied from 0 to 90 knots and altitudes varied from 0' to 1000'. Targets imaged include roads, freeways, railroads, houses, industrial buildings, power plants, people, streams, rivers, bridges, cars, trucks, trains, boats, planes, runways, treelines, shorelines, and the horizon. The imaging system withstood vibration and temperature variations, but experienced some RF interference. The flight test demonstrated the system's capabilities as an airborne navigation and surveillance aid. It also performed in a personnel recovery scenario.

StopWatch: The preliminary evaluation of a smartwatch-based system for passive detection of cigarette smoking.

PubMed

Skinner, Andrew L; Stone, Christopher J; Doughty, Hazel; Munafò, Marcus R

2018-01-24

Recent developments in smoking cessation support systems and interventions have highlighted the requirement for unobtrusive, passive ways to measure smoking behaviour. A number of systems have been developed for this that either use bespoke sensing technology, or expensive combinations of wearables and smartphones. Here we present StopWatch, a system for passive detection of cigarette smoking that runs on a low-cost smartwatch and does not require additional sensing or a connected smartphone. Our system uses motion data from the accelerometer and gyroscope in an Android smartwatch to detect the signature hand movements of cigarette smoking. It uses machine learning techniques to transform raw motion data into motion features, and in turn into individual drags and instances of smoking. These processes run on the smartwatch, and do not require a smartphone. We conducted preliminary validations of the system in daily smokers (n=13) in laboratory and free-living conditions running on an Android LG G-Watch. In free-living conditions, over a 24-hour period, the system achieved precision of 86% and recall of 71%. StopWatch is a system for passive measurement of cigarette smoking that runs entirely on a commercially available Android smartwatch. It requires no smartphone so the cost is low, and needs no bespoke sensing equipment so participant burden is also low. Performance is currently lower than other more expensive and complex systems, though adequate for some applications. Future developments will focus on enhancing performance, validation on a range of smartwatches, and detection of electronic cigarette use. We present a low-cost, smartwatch-based system for passive detection of cigarette smoking. It uses data from the motion sensors in the watch to identify the signature hand movements of cigarette smoking. The system will provide the detailed measures of individual smoking behaviour needed for context-triggered just-in-time smoking cessation support systems, and to

Integrated passive/active vibration absorber for multi-story buildings

NASA Technical Reports Server (NTRS)

Lee-Glauser, Gina J.; Ahmadi, Goodarz; Horta, Lucas G.

1995-01-01

Passive isolator, active vibration absorber, and an integrated passive/active (hybrid) control are studied for their effectiveness in reducing structural vibration under seismic excitations. For the passive isolator, a laminated rubber bearing base isolator which has been studied and used extensively by researchers and seismic designers is considered. An active vibration absorber concept, which can provide guaranteed closed-loop stability with minimum knowledge of the controlled system, is used to reduce the passive isolator displacement and to suppress the top floor vibration. A three-story building model is used for the numerical simulation. The performance of an active vibration absorber and a hybrid vibration controller in reducing peak structural responses is compared with the passively isolated structural response and with absence of vibration control systems under the N00W component of El Centro 1940 and N90W component of the Mexico City earthquake excitation records. The results show that the integrated passive/active vibration control system is most effective in suppressing the peak structural acceleration for the El Centro 1940 earthquake when compared with the passive or active vibration absorber alone. The active vibration absorber, however, is the only system that suppresses the peak acceleration of the structure for the Mexico City 1985 earthquake.

Passive 350 GHz Video Imaging Systems for Security Applications

NASA Astrophysics Data System (ADS)

Heinz, E.; May, T.; Born, D.; Zieger, G.; Anders, S.; Zakosarenko, V.; Meyer, H.-G.; Schäffel, C.

2015-10-01

Passive submillimeter-wave imaging is a concept that has been in the focus of interest as a promising technology for personal security screening for a number of years. In contradiction to established portal-based millimeter-wave scanning techniques, it allows for scanning people from a distance in real time with high throughput and without a distinct inspection procedure. This opens up new possibilities for scanning, which directly address an urgent security need of modern societies: protecting crowds and critical infrastructure from the growing threat of individual terror attacks. Considering the low radiometric contrast of indoor scenes in the submillimeter range, this objective calls for an extremely high detector sensitivity that can only be achieved using cooled detectors. Our approach to this task is a series of passive standoff video cameras for the 350 GHz band that represent an evolving concept and a continuous development since 2007. Arrays of superconducting transition-edge sensors (TES), operated at temperatures below 1 K, are used as radiation detectors. By this means, background limited performance (BLIP) mode is achieved, providing the maximum possible signal to noise ratio. At video rates, this leads to a temperature resolution well below 1 K. The imaging system is completed by reflector optics based on free-form mirrors. For object distances of 5-25 m, a field of view up to 2 m height and a diffraction-limited spatial resolution in the order of 1-2 cm is provided. Opto-mechanical scanning systems are part of the optical setup and capable of frame rates of up to 25 frames per second.

A Review of Passive RFID Tag Antenna-Based Sensors and Systems for Structural Health Monitoring Applications.

PubMed

Zhang, Jun; Tian, Gui Yun; Marindra, Adi M J; Sunny, Ali Imam; Zhao, Ao Bo

2017-01-29

In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well.

Analysis of Alerting System Failures in Commercial Aviation Accidents

NASA Technical Reports Server (NTRS)

Mumaw, Randall J.

2017-01-01

The role of an alerting system is to make the system operator (e.g., pilot) aware of an impending hazard or unsafe state so the hazard can be avoided or managed successfully. A review of 46 commercial aviation accidents (between 1998 and 2014) revealed that, in the vast majority of events, either the hazard was not alerted or relevant hazard alerting occurred but failed to aid the flight crew sufficiently. For this set of events, alerting system failures were placed in one of five phases: Detection, Understanding, Action Selection, Prioritization, and Execution. This study also reviewed the evolution of alerting system schemes in commercial aviation, which revealed naive assumptions about pilot reliability in monitoring flight path parameters; specifically, pilot monitoring was assumed to be more effective than it actually is. Examples are provided of the types of alerting system failures that have occurred, and recommendations are provided for alerting system improvements.

Utility-scale system preventive and failure-related maintenance

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

Jennings, C.; Hutchinson, P.

1995-11-01

This paper describes the design and performance background on PVUSA utility-scale systems at Davis and Kerman, California, and reports on a preventative and failure-related maintenance approach and costs.

Passive range estimation using dual baseline triangulation

NASA Astrophysics Data System (ADS)

Pieper, Ronald J.; Cooper, Alfred W.; Pelegris, G.

1996-03-01

Modern combat systems based on active radar sensing suffer disadvantages against low-flying targets in cluttered backgrounds. Use of passive infrared sensors with these systems, either in cooperation or as an alternative, shows potential for improving target detection and declaration range for targets crossing the horizon. Realization of this potential requires fusion of target position data from dissimilar sensors, or passive sensor measurement of target range. The availability of passive sensors that can supply both range and bearing data on such targets would significantly extend the robustness of an integrated ship self-defense system. This paper considers a new method of range determination with passive sensors based on the principle of triangulation, extending the principle to two orthogonal baselines. The performance of single or double baseline triangulation depends on sensor bearing precision and direction to target. An expression for maximum triangulation range at a required accuracy is derived as a function of polar angle relative to the center of the dual-baseline system. Limitations in the dual- baseline model due to the geometrically assessed horizon are also considered.

High sensitivity broadband 360GHz passive receiver for TeraSCREEN

NASA Astrophysics Data System (ADS)

Wang, Hui; Oldfield, Matthew; Maestrojuán, Itziar; Platt, Duncan; Brewster, Nick; Viegas, Colin; Alderman, Byron; Ellison, Brian N.

2016-05-01

TeraSCREEN is an EU FP7 Security project aimed at developing a combined active, with frequency channel centered at 360 GHz, and passive, with frequency channels centered at 94, 220 and 360 GHz, imaging system for border controls in airport and commercial ferry ports. The system will include automatic threat detection and classification and has been designed with a strong focus on the ethical, legal and practical aspects of operating in these environments and with the potential threats in mind. Furthermore, both the passive and active systems are based on array receivers with the active system consisting of a 16 element MIMO FMCW radar centered at 360 GHz with a bandwidth of 30 GHz utilizing a custom made direct digital synthesizer. The 16 element passive receiver system at 360 GHz uses commercial Gunn diode oscillators at 90 GHz followed by custom made 90 to 180 GHz frequency doublers supplying the local oscillator for 360 GHz sub-harmonic mixers. This paper describes the development of the passive antenna module, local oscillator chain, frequency mixers and detectors used in the passive receiver array of this system. The complete passive receiver chain is characterized in this paper.

Optimum radars and filters for the passive sphere system

NASA Technical Reports Server (NTRS)

Luers, J. K.; Soltes, A.

1971-01-01

Studies have been conducted to determine the influence of the tracking radar and data reduction technique on the accuracy of the meteorological measurements made in the 30 to 100 kilometer altitude region by the ROBIN passive falling sphere. A survey of accuracy requirements was made of agencies interested in data from this region of the atmosphere. In light of these requirements, various types of radars were evaluated to determine the tracking system most applicable to the ROBIN, and methods were developed to compute the errors in wind and density that arise from noise errors in the radar supplied data. The effects of launch conditions on the measurements were also examined. Conclusions and recommendations have been made concerning the optimum tracking and data reduction techniques for the ROBIN falling sphere system.

Robust passive control for a class of uncertain neutral systems based on sliding mode observer.

PubMed

Liu, Zhen; Zhao, Lin; Kao, Yonggui; Gao, Cunchen

2017-01-01

The passivity-based sliding mode control (SMC) problem for a class of uncertain neutral systems with unmeasured states is investigated. Firstly, a particular non-fragile state observer is designed to generate the estimations of the system states, based upon which a novel integral-type sliding surface function is established for the control process. Secondly, a new sufficient condition for robust asymptotic stability and passivity of the resultant sliding mode dynamics (SMDs) is obtained in terms of linear matrix inequalities (LMIs). Thirdly, the finite-time reachability of the predesigned sliding surface is ensured by resorting to a novel adaptive SMC law. Finally, the validity and superiority of the scheme are justified via several examples. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

A survey of design methods for failure detection in dynamic systems

NASA Technical Reports Server (NTRS)

Willsky, A. S.

1975-01-01

A number of methods for detecting abrupt changes (such as failures) in stochastic dynamical systems are surveyed. The class of linear systems is concentrated on but the basic concepts, if not the detailed analyses, carry over to other classes of systems. The methods surveyed range from the design of specific failure-sensitive filters, to the use of statistical tests on filter innovations, to the development of jump process formulations. Tradeoffs in complexity versus performance are discussed.

A survey of design methods for failure detection in dynamic systems

NASA Technical Reports Server (NTRS)

Willsky, A. S.

1975-01-01

A number of methods for the detection of abrupt changes (such as failures) in stochastic dynamical systems were surveyed. The class of linear systems were emphasized, but the basic concepts, if not the detailed analyses, carry over to other classes of systems. The methods surveyed range from the design of specific failure-sensitive filters, to the use of statistical tests on filter innovations, to the development of jump process formulations. Tradeoffs in complexity versus performance are discussed.

Cascading Failures in Bi-partite Graphs: Model for Systemic Risk Propagation

PubMed Central

Huang, Xuqing; Vodenska, Irena; Havlin, Shlomo; Stanley, H. Eugene

2013-01-01

As economic entities become increasingly interconnected, a shock in a financial network can provoke significant cascading failures throughout the system. To study the systemic risk of financial systems, we create a bi-partite banking network model composed of banks and bank assets and propose a cascading failure model to describe the risk propagation process during crises. We empirically test the model with 2007 US commercial banks balance sheet data and compare the model prediction of the failed banks with the real failed banks after 2007. We find that our model efficiently identifies a significant portion of the actual failed banks reported by Federal Deposit Insurance Corporation. The results suggest that this model could be useful for systemic risk stress testing for financial systems. The model also identifies that commercial rather than residential real estate assets are major culprits for the failure of over 350 US commercial banks during 2008–2011. PMID:23386974

Stress Transfer and Structural Failure of Bilayered Material Systems

NASA Astrophysics Data System (ADS)

Prieto-Munoz, Pablo Arthur

Bilayered material systems are common in naturally formed or artificially engineered structures. Understanding how loads transfer within these structural systems is necessary to predict failure and develop effective designs. Existing methods for evaluating the stress transfer in bilayered materials are limited to overly simplified models or require experimental calibration. As a result, these methods have failed to accurately account for such structural failures as the creep induced roofing panel collapse of Boston's I-90 connector tunnel, which was supported by adhesive anchors. The one-dimensional stress analyses currently used for adhesive anchor design cannot account for viscoelastic creep failure, and consequently results in dangerously under-designed structural systems. In this dissertation, a method for determining the two-dimensional stress and displacement fields for a generalized bilayered material system is developed, and proposes a closed-form analytical solution. A general linear-elastic solution is first proposed by decoupling the elastic governing equations from one another through the so-called plane assumption. Based on this general solution, an axisymmetric problem and a plane strain problem are formulated. These are applied to common bilayered material systems such as: (1) concrete adhesive anchors, (2) material coatings, (3) asphalt pavements, and (4) layered sedimentary rocks. The stress and displacement fields determined by this analytical analysis are validated through the use of finite element models. Through the correspondence principle, the linear-elastic solution is extended to consider time-dependent viscoelastic material properties, thus facilitating the analysis of adhesive anchors and asphalt pavements while incorporating their viscoelastic material behavior. Furthermore, the elastic stress analysis can explain the fracturing phenomenon of material coatings, pavements, and layered rocks, successfully predicting their fracture

Extended Range Passive Wireless Tag System and Method

NASA Technical Reports Server (NTRS)

Fink, Patrick W. (Inventor); Lin, Gregory Y. (Inventor); Kennedy, Timothy F. (Inventor)

2013-01-01

A passive wireless tag assembly comprises a plurality of antennas and transmission lines interconnected with circuitry and constructed and arranged in a Van Atta array or configuration to reflect an interrogator signal in the direction from where it came. The circuitry may comprise at least one surface acoustic wave (SAW)-based circuit that functions as a signal reflector and is operatively connected with an information circuit. In another embodiment, at least one delay circuit and/or at least one passive modulation circuit(s) are utilized. In yet another embodiment, antennas connected to SAW-based devices are mounted to at least one of the orthogonal surfaces of a corner reflector.

Development of a GIS-based failure investigation system for highway soil slopes

NASA Astrophysics Data System (ADS)

Ramanathan, Raghav; Aydilek, Ahmet H.; Tanyu, Burak F.

2015-06-01

A framework for preparation of an early warning system was developed for Maryland, using a GIS database and a collective overlay of maps that highlight highway slopes susceptible to soil slides or slope failures in advance through spatial and statistical analysis. Data for existing soil slope failures was collected from geotechnical reports and field visits. A total of 48 slope failures were recorded and analyzed. Six factors, including event precipitation, geological formation, land cover, slope history, slope angle, and elevation were considered to affect highway soil slope stability. The observed trends indicate that precipitation and poor surface or subsurface drainage conditions are principal factors causing slope failures. 96% of the failed slopes have an open drainage section. A majority of the failed slopes lie in regions with relatively high event precipitation ( P>200 mm). 90% of the existing failures are surficial erosion type failures, and only 1 out of the 42 slope failures is deep rotational type failure. More than half of the analyzed slope failures have occurred in regions having low density land cover. 46% of failures are on slopes with slope angles between 20° and 30°. Influx of more data relating to failed slopes should give rise to more trends, and thus the developed slope management system will aid the state highway engineers in prudential budget allocation and prioritizing different remediation projects based on the literature reviewed on the principles, concepts, techniques, and methodology for slope instability evaluation (Leshchinsky et al., 2015).

Robust controller designs for second-order dynamic system: A virtual passive approach

NASA Technical Reports Server (NTRS)

Juang, Jer-Nan; Phan, Minh

1990-01-01

A robust controller design is presented for second-order dynamic systems. The controller is model-independent and itself is a virtual second-order dynamic system. Conditions on actuator and sensor placements are identified for controller designs that guarantee overall closed-loop stability. The dynamic controller can be viewed as a virtual passive damping system that serves to stabilize the actual dynamic system. The control gains are interpreted as virtual mass, spring, and dashpot elements that play the same roles as actual physical elements in stability analysis. Position, velocity, and acceleration feedback are considered. Simple examples are provided to illustrate the physical meaning of this controller design.

Analysis on Target Detection and Classification in LTE Based Passive Forward Scattering Radar.

PubMed

Raja Abdullah, Raja Syamsul Azmir; Abdul Aziz, Noor Hafizah; Abdul Rashid, Nur Emileen; Ahmad Salah, Asem; Hashim, Fazirulhisyam

2016-09-29

The passive bistatic radar (PBR) system can utilize the illuminator of opportunity to enhance radar capability. By utilizing the forward scattering technique and procedure into the specific mode of PBR can provide an improvement in target detection and classification. The system is known as passive Forward Scattering Radar (FSR). The passive FSR system can exploit the peculiar advantage of the enhancement in forward scatter radar cross section (FSRCS) for target detection. Thus, the aim of this paper is to show the feasibility of passive FSR for moving target detection and classification by experimental analysis and results. The signal source is coming from the latest technology of 4G Long-Term Evolution (LTE) base station. A detailed explanation on the passive FSR receiver circuit, the detection scheme and the classification algorithm are given. In addition, the proposed passive FSR circuit employs the self-mixing technique at the receiver; hence the synchronization signal from the transmitter is not required. The experimental results confirm the passive FSR system's capability for ground target detection and classification. Furthermore, this paper illustrates the first classification result in the passive FSR system. The great potential in the passive FSR system provides a new research area in passive radar that can be used for diverse remote monitoring applications.

A Review of Passive RFID Tag Antenna-Based Sensors and Systems for Structural Health Monitoring Applications

PubMed Central

Zhang, Jun; Tian, Gui Yun; Marindra, Adi M. J.; Sunny, Ali Imam; Zhao, Ao Bo

2017-01-01

In recent few years, the antenna and sensor communities have witnessed a considerable integration of radio frequency identification (RFID) tag antennas and sensors because of the impetus provided by internet of things (IoT) and cyber-physical systems (CPS). Such types of sensor can find potential applications in structural health monitoring (SHM) because of their passive, wireless, simple, compact size, and multimodal nature, particular in large scale infrastructures during their lifecycle. The big data from these ubiquitous sensors are expected to generate a big impact for intelligent monitoring. A remarkable number of scientific papers demonstrate the possibility that objects can be remotely tracked and intelligently monitored for their physical/chemical/mechanical properties and environment conditions. Most of the work focuses on antenna design, and significant information has been generated to demonstrate feasibilities. Further information is needed to gain deep understanding of the passive RFID antenna sensor systems in order to make them reliable and practical. Nevertheless, this information is scattered over much literature. This paper is to comprehensively summarize and clearly highlight the challenges and state-of-the-art methods of passive RFID antenna sensors and systems in terms of sensing and communication from system point of view. Future trends are also discussed. The future research and development in UK are suggested as well. PMID:28146067

Parallel Processing Systems for Passive Ranging During Helicopter Flight

NASA Technical Reports Server (NTRS)

Sridhar, Bavavar; Suorsa, Raymond E.; Showman, Robert D. (Technical Monitor)

1994-01-01

The complexity of rotorcraft missions involving operations close to the ground result in high pilot workload. In order to allow a pilot time to perform mission-oriented tasks, sensor-aiding and automation of some of the guidance and control functions are highly desirable. Images from an electro-optical sensor provide a covert way of detecting objects in the flight path of a low-flying helicopter. Passive ranging consists of processing a sequence of images using techniques based on optical low computation and recursive estimation. The passive ranging algorithm has to extract obstacle information from imagery at rates varying from five to thirty or more frames per second depending on the helicopter speed. We have implemented and tested the passive ranging algorithm off-line using helicopter-collected images. However, the real-time data and computation requirements of the algorithm are beyond the capability of any off-the-shelf microprocessor or digital signal processor. This paper describes the computational requirements of the algorithm and uses parallel processing technology to meet these requirements. Various issues in the selection of a parallel processing architecture are discussed and four different computer architectures are evaluated regarding their suitability to process the algorithm in real-time. Based on this evaluation, we conclude that real-time passive ranging is a realistic goal and can be achieved with a short time.

Passive-solar homes for Texas

NASA Astrophysics Data System (ADS)

Garrison, M. L.

1982-06-01

Acceptance of passive solar technologies has been slow within the conventional building trades in Texas because it is a common misconception that solar is expensive, and data on local applications is severely limited or nonexistent. It is the purpose of this solar development to move passive solar design into the mainstream of public acceptance by helping to overcome and eliminate these barriers. Specifically, the goal is to develop a set of regional climatic building standards to help guide the conventional building trade toward the utilization of soft energy systems which will reduce overall consumption at a price and convenience most Texans can afford. To meet this objective, eight sample passive design structures are presented. These designs represent state of the art regional applications of passive solar space conditioning. The methodology used in the passive solar design process included: analysis of regional climatic data; analysis of historical regional building prototypes; determination of regional climatic design priorities and assets; prototypical design models for the discretionary housing market; quantitative thermal analysis of prototypical designs; and construction drawings of building prototypes.

Evaluation of Non-Chromate Passivations on Electroplated gamma-Phase Zinc Nickel

NASA Astrophysics Data System (ADS)

Volz, Steven Michael

This research focused on the corrosion response and electrochemical behavior of electroplated low hydrogen embrittlement alkaline gamma-phase zinc nickel with passivation layers. The motivation was the need to replace hexavalent chromium conversion coatings in military grade electrical systems with a more environment friendly alternative. The passivation layers were employed for the purpose of mitigating corrosion attack while maintaining low contact resistance. Trivalent chromium-based passivations and cerium-based passivations were compared against the currently used hexavalent chromium conversion coating. The coating systems were compared using electrochemical impedance spectroscopy, cyclic potentiodymanic scans, salt spray exposure testing, electrical resistance measurements, microstructure analysis, and compositional analysis. Coating systems with lower open circuit had a lower corrosion current and performed better during salt spray testing. All of the systems evaluated had corrosion products consistent with oxidized zinc compounds but the morphology of the passivation was dependent on the passivation. The electrical contact resistance ranged from 1 to 108 mO/cm 2, after salt spray testing. Two versions of Trivalent chromium-based passivations, were able to meet military performance specifications after corrosion testing.

Failure mode and effect analysis-based quality assurance for dynamic MLC tracking systems

PubMed Central

Sawant, Amit; Dieterich, Sonja; Svatos, Michelle; Keall, Paul

2010-01-01

Purpose: To develop and implement a failure mode and effect analysis (FMEA)-based commissioning and quality assurance framework for dynamic multileaf collimator (DMLC) tumor tracking systems. Methods: A systematic failure mode and effect analysis was performed for a prototype real-time tumor tracking system that uses implanted electromagnetic transponders for tumor position monitoring and a DMLC for real-time beam adaptation. A detailed process tree of DMLC tracking delivery was created and potential tracking-specific failure modes were identified. For each failure mode, a risk probability number (RPN) was calculated from the product of the probability of occurrence, the severity of effect, and the detectibility of the failure. Based on the insights obtained from the FMEA, commissioning and QA procedures were developed to check (i) the accuracy of coordinate system transformation, (ii) system latency, (iii) spatial and dosimetric delivery accuracy, (iv) delivery efficiency, and (v) accuracy and consistency of system response to error conditions. The frequency of testing for each failure mode was determined from the RPN value. Results: Failures modes with RPN≥125 were recommended to be tested monthly. Failure modes with RPN<125 were assigned to be tested during comprehensive evaluations, e.g., during commissioning, annual quality assurance, and after major software∕hardware upgrades. System latency was determined to be ∼193 ms. The system showed consistent and accurate response to erroneous conditions. Tracking accuracy was within 3%–3 mm gamma (100% pass rate) for sinusoidal as well as a wide variety of patient-derived respiratory motions. The total time taken for monthly QA was ∼35 min, while that taken for comprehensive testing was ∼3.5 h. Conclusions: FMEA proved to be a powerful and flexible tool to develop and implement a quality management (QM) framework for DMLC tracking. The authors conclude that the use of FMEA-based QM ensures efficient

Direct Adaptive Control of Systems with Actuator Failures: State of the Art and Continuing Challenges

NASA Technical Reports Server (NTRS)

Tao, Gang; Joshi, Suresh M.

2008-01-01

In this paper, the problem of controlling systems with failures and faults is introduced, and an overview of recent work on direct adaptive control for compensation of uncertain actuator failures is presented. Actuator failures may be characterized by some unknown system inputs being stuck at some unknown (fixed or varying) values at unknown time instants, that cannot be influenced by the control signals. The key task of adaptive compensation is to design the control signals in such a manner that the remaining actuators can automatically and seamlessly take over for the failed ones, and achieve desired stability and asymptotic tracking. A certain degree of redundancy is necessary to accomplish failure compensation. The objective of adaptive control design is to effectively use the available actuation redundancy to handle failures without the knowledge of the failure patterns, parameters, and time of occurrence. This is a challenging problem because failures introduce large uncertainties in the dynamic structure of the system, in addition to parametric uncertainties and unknown disturbances. The paper addresses some theoretical issues in adaptive actuator failure compensation: actuator failure modeling, redundant actuation requirements, plant-model matching, error system dynamics, adaptation laws, and stability, tracking, and performance analysis. Adaptive control designs can be shown to effectively handle uncertain actuator failures without explicit failure detection. Some open technical challenges and research problems in this important research area are discussed.

Towards passive brain-computer interfaces: applying brain-computer interface technology to human-machine systems in general.

PubMed

Zander, Thorsten O; Kothe, Christian

2011-04-01

Cognitive monitoring is an approach utilizing realtime brain signal decoding (RBSD) for gaining information on the ongoing cognitive user state. In recent decades this approach has brought valuable insight into the cognition of an interacting human. Automated RBSD can be used to set up a brain-computer interface (BCI) providing a novel input modality for technical systems solely based on brain activity. In BCIs the user usually sends voluntary and directed commands to control the connected computer system or to communicate through it. In this paper we propose an extension of this approach by fusing BCI technology with cognitive monitoring, providing valuable information about the users' intentions, situational interpretations and emotional states to the technical system. We call this approach passive BCI. In the following we give an overview of studies which utilize passive BCI, as well as other novel types of applications resulting from BCI technology. We especially focus on applications for healthy users, and the specific requirements and demands of this user group. Since the presented approach of combining cognitive monitoring with BCI technology is very similar to the concept of BCIs itself we propose a unifying categorization of BCI-based applications, including the novel approach of passive BCI.

Failure detection and identification for a reconfigurable flight control system

NASA Technical Reports Server (NTRS)

Dallery, Francois

1987-01-01

Failure detection and identification logic for a fault-tolerant longitudinal control system were investigated. Aircraft dynamics were based upon the cruise condition for a hypothetical transonic business jet transport configuration. The fault-tolerant control system consists of conventional control and estimation plus a new outer loop containing failure detection, identification, and reconfiguration (FDIR) logic. It is assumed that the additional logic has access to all measurements, as well as to the outputs of the control and estimation logic. The pilot may also command the FDIR logic to perform special tests.

Design of a novel passive flexure-based mechanism for microelectromechanical system optical switch assembly

NASA Astrophysics Data System (ADS)

Zhang, Jianbin; Sun, Xiantao; Chen, Weihai; Chen, Wenjie; Jiang, Lusha

2014-12-01

In microelectromechanical system (MEMS) optical switch assembly, the collision always exists between the optical fiber and the edges of the U-groove due to the positioning errors between them. It will cause the irreparable damage since the optical fiber and the silicon-made U-groove are usually very fragile. Typical solution is first to detect the positioning errors by the machine vision or high-resolution sensors and then to actively eliminate them with the aid of the motion of precision mechanisms. However, this method will increase the cost and complexity of the system. In this paper, we present a passive compensation method to accommodate the positioning errors. First, we study the insertion process of the optical fiber into the U-groove to analyze all possible positioning errors as well as the conditions of successful insertion. Then, a novel passive flexure-based mechanism based on the remote center of compliance concept is designed to satisfy the required insertion condition. The pseudo-rigid-body-model method is utilized to calculate the stiffness of the mechanism along the different directions, which is verified by finite element analysis (FEA). Finally, a prototype of the passive flexure-based mechanism is fabricated for performance tests. Both FEA and experimental results indicate that the designed mechanism can be used to the MEMS optical switch assembly.

Design of a novel passive flexure-based mechanism for microelectromechanical system optical switch assembly.

PubMed

Zhang, Jianbin; Sun, Xiantao; Chen, Weihai; Chen, Wenjie; Jiang, Lusha

2014-12-01

In microelectromechanical system (MEMS) optical switch assembly, the collision always exists between the optical fiber and the edges of the U-groove due to the positioning errors between them. It will cause the irreparable damage since the optical fiber and the silicon-made U-groove are usually very fragile. Typical solution is first to detect the positioning errors by the machine vision or high-resolution sensors and then to actively eliminate them with the aid of the motion of precision mechanisms. However, this method will increase the cost and complexity of the system. In this paper, we present a passive compensation method to accommodate the positioning errors. First, we study the insertion process of the optical fiber into the U-groove to analyze all possible positioning errors as well as the conditions of successful insertion. Then, a novel passive flexure-based mechanism based on the remote center of compliance concept is designed to satisfy the required insertion condition. The pseudo-rigid-body-model method is utilized to calculate the stiffness of the mechanism along the different directions, which is verified by finite element analysis (FEA). Finally, a prototype of the passive flexure-based mechanism is fabricated for performance tests. Both FEA and experimental results indicate that the designed mechanism can be used to the MEMS optical switch assembly.

Margins Associated with Loss of Assured Safety for Systems with Multiple Time-Dependent Failure Modes.

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

Helton, Jon C.; Brooks, Dusty Marie; Sallaberry, Cedric Jean-Marie.

Representations for margins associated with loss of assured safety (LOAS) for weak link (WL)/strong link (SL) systems involving multiple time-dependent failure modes are developed. The following topics are described: (i) defining properties for WLs and SLs, (ii) background on cumulative distribution functions (CDFs) for link failure time, link property value at link failure, and time at which LOAS occurs, (iii) CDFs for failure time margins defined by (time at which SL system fails) – (time at which WL system fails), (iv) CDFs for SL system property values at LOAS, (v) CDFs for WL/SL property value margins defined by (property valuemore » at which SL system fails) – (property value at which WL system fails), and (vi) CDFs for SL property value margins defined by (property value of failing SL at time of SL system failure) – (property value of this SL at time of WL system failure). Included in this presentation is a demonstration of a verification strategy based on defining and approximating the indicated margin results with (i) procedures based on formal integral representations and associated quadrature approximations and (ii) procedures based on algorithms for sampling-based approximations.« less

A Report on Simulation-Driven Reliability and Failure Analysis of Large-Scale Storage Systems

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

Wan, Lipeng; Wang, Feiyi; Oral, H. Sarp

High-performance computing (HPC) storage systems provide data availability and reliability using various hardware and software fault tolerance techniques. Usually, reliability and availability are calculated at the subsystem or component level using limited metrics such as, mean time to failure (MTTF) or mean time to data loss (MTTDL). This often means settling on simple and disconnected failure models (such as exponential failure rate) to achieve tractable and close-formed solutions. However, such models have been shown to be insufficient in assessing end-to-end storage system reliability and availability. We propose a generic simulation framework aimed at analyzing the reliability and availability of storagemore » systems at scale, and investigating what-if scenarios. The framework is designed for an end-to-end storage system, accommodating the various components and subsystems, their interconnections, failure patterns and propagation, and performs dependency analysis to capture a wide-range of failure cases. We evaluate the framework against a large-scale storage system that is in production and analyze its failure projections toward and beyond the end of lifecycle. We also examine the potential operational impact by studying how different types of components affect the overall system reliability and availability, and present the preliminary results« less

Hydrodynamic interactions between a self-rotation rotator and passive particles

NASA Astrophysics Data System (ADS)

Ouyang, Zhenyu; Lin, Jian-Zhong; Ku, Xiaoke

2017-10-01

In this paper, we numerically investigate the hydrodynamic interaction between a self-rotation rotator and passive particles in a two-dimensional confined cavity at two typical Reynolds numbers according to the different flow features. Both the fluid-particle interaction and particle-particle interaction through fluid media are taken into consideration. The results show that from the case of a rotator and one passive particle to the case of a rotator and two passive particles, the system becomes much more complex because the relative displacement between the rotator and the passive particles and the velocity of passive particles are strongly dependent on the Reynolds number and the initial position of passive particles. For the system of two particles, the passive particle gradually departs from the rotator although its relative displacement to the rotator exhibits a periodic oscillation at the lower Reynolds number. Furthermore, the relative distance between the two particles and the rotator's rotational frequency are responsible for the oscillation amplitude and frequency of the passive particle's velocity. For the system of three particles, the passive particle's velocities exhibit a superposition of a large amplitude oscillation and a small amplitude oscillation at the lower Reynolds number, and the large amplitude oscillation will disappear at the higher Reynolds number. The change of the included angle of the two passive particles is dependent on the initial positions of the passive particles at the lower Reynolds number, whereas the included angle of the two passive particles finally approaches a fixed value at the higher Reynolds number. It is interesting that the two passive particles periodically approach and depart from each other when the included angle is not equal to π, while all the three particles (including the rotator) keep the positions in a straight line when the included angle is equal to π because the interference between two passive

The Development of Advanced Passive Acoustic Monitoring Systems Using microMARS Technology

DTIC Science & Technology

2015-09-30

localization that will be available in a number of configurations for deep and shallow water environments alike. OBJECTIVES The project has two...through two test series, first targeting the GPS synchronized shallow water and then the self-synchronized deep water configurations. The project will...main objectives: 1. Development of all the components of a compact passive acoustic monitoring system suitable both for shallow water moored

Intelligent failure-tolerant control

NASA Technical Reports Server (NTRS)

Stengel, Robert F.

1991-01-01

An overview of failure-tolerant control is presented, beginning with robust control, progressing through parallel and analytical redundancy, and ending with rule-based systems and artificial neural networks. By design or implementation, failure-tolerant control systems are 'intelligent' systems. All failure-tolerant systems require some degrees of robustness to protect against catastrophic failure; failure tolerance often can be improved by adaptivity in decision-making and control, as well as by redundancy in measurement and actuation. Reliability, maintainability, and survivability can be enhanced by failure tolerance, although each objective poses different goals for control system design. Artificial intelligence concepts are helpful for integrating and codifying failure-tolerant control systems, not as alternatives but as adjuncts to conventional design methods.

Control system failure monitoring using generalized parity relations. M.S. Thesis Interim Technical Report

NASA Technical Reports Server (NTRS)

Vanschalkwyk, Christiaan Mauritz

1991-01-01

Many applications require that a control system must be tolerant to the failure of its components. This is especially true for large space-based systems that must work unattended and with long periods between maintenance. Fault tolerance can be obtained by detecting the failure of the control system component, determining which component has failed, and reconfiguring the system so that the failed component is isolated from the controller. Component failure detection experiments that were conducted on an experimental space structure, the NASA Langley Mini-Mast are presented. Two methodologies for failure detection and isolation (FDI) exist that do not require the specification of failure modes and are applicable to both actuators and sensors. These methods are known as the Failure Detection Filter and the method of Generalized Parity Relations. The latter method was applied to three different sensor types on the Mini-Mast. Failures were simulated in input-output data that were recorded during operation of the Mini-Mast. Both single and double sensor parity relations were tested and the effect of several design parameters on the performance of these relations is discussed. The detection of actuator failures is also treated. It is shown that in all the cases it is possible to identify the parity relations directly from input-output data. Frequency domain analysis is used to explain the behavior of the parity relations.

A passive cooling system proposal for multifunction and high-power displays

NASA Astrophysics Data System (ADS)

Tari, Ilker

2013-03-01

Flat panel displays are conventionally cooled by internal natural convection, which constrains the possible rate of heat transfer from the panel. On one hand, during the last few years, the power consumption and the related cooling requirement for 1080p displays have decreased mostly due to energy savings by the switch to LED backlighting and more efficient electronics. However, on the other hand, the required cooling rate recently started to increase with new directions in the industry such as 3D displays, and ultra-high-resolution displays (recent 4K announcements and planned introduction of 8K). In addition to these trends in display technology itself, there is also a trend to integrate consumer entertainment products into displays with the ultimate goal of designing a multifunction device replacing the TV, the media player, the PC, the game console and the sound system. Considering the increasing power requirement for higher fidelity in video processing, these multifunction devices tend to generate very high heat fluxes, which are impossible to dissipate with internal natural convection. In order to overcome this obstacle, instead of active cooling with forced convection that comes with drawbacks of noise, additional power consumption, and reduced reliability, a passive cooling system relying on external natural convection and radiation is proposed here. The proposed cooling system consists of a heat spreader flat heat pipe and aluminum plate-finned heat sink with anodized surfaces. For this system, the possible maximum heat dissipation rates from the standard size panels (in 26-70 inch range) are estimated by using our recently obtained heat transfer correlations for the natural convection from aluminum plate-finned heat sinks together with the surface-to-surface radiation. With the use of the proposed passive cooling system, the possibility of dissipating very high heat rates is demonstrated, hinting a promising green alternative to active cooling.

Transdermal therapeutic systems for memantine delivery. Comparison of passive and iontophoretic transport.

PubMed

Del Río-Sancho, S; Serna-Jiménez, C E; Sebastián-Morelló, M; Calatayud-Pascual, M A; Balaguer-Fernández, C; Femenía-Font, A; Kalia, Y N; Merino, V; López-Castellano, A

2017-01-30

Memantine is a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist used in the treatment of moderate to severe dementia including the symptoms of Alzheimer's disease (AD). It is administered orally but compliance, swallowing problems and the routine use of multiple medications in elderly AD patients means that an alternative route of administration would be of interest. The aim of the present study was to develop memantine hydrochloride occlusive transdermal therapeutic systems (TTS) for passive and iontophoretic delivery across the skin. Polyvinyl pyrrolidone (PVP) and a mixture with polyvinyl alcohol (PVA) were employed as polymeric matrices. The study involved the TTS characterization in addition to quantification of the memantine transport across porcine skin in vitro. The evaluation of the TTS physical properties suggested that systems were made more mechanically resistant by including PVA (6%) or high concentrations of PVP (24%). Moreover, a linear correlation was observed between the concentration of PVP and the bioadhesion of the systems. Drug delivery experiments showed that the highest transdermal flux provided by a passive TTS (PVP 24% w/w limonene) was 8.89±0.81μgcm -2 h -1 whereas the highest iontophoretic transport was 46.4±3.6μgcm -2 h -1 . These innovative TTS would enable two dosage regimens that could lead to therapeutic plasma concentrations. Copyright © 2016 Elsevier B.V. All rights reserved.

The passive-aggressive organization.

PubMed

Kaplan, Robert S; Norton, David P

2005-10-01

Passive-aggressive organizations are friendly places to work: People are congenial, conflict is rare, and consensus is easy to reach. But, at the end of the day, even the best proposals fail to gain traction, and a company can go nowhere so imperturbably that it's easy to pretend everything is fine. Such companies are not necessarily saddled with mulishly passive-aggressive employees. Rather, they are filled with mostly well-intentioned people who are the victirms of flawed processes and policies. Commonly, a growing company's halfhearted or poorly thought-out attempts to decentralize give rise to multiple layers of managers, whose authority for making decisions becomes increasingly unclear. Some managers, as a result, hang back, while others won't own up to the calls they've made, inviting colleagues to second-guess or overturn the decisions. In such organizations, information does not circulate freely, and that makes it difficult for workers to understand the impact of their actions on company performance and for managers to correctly appraise employees' value to the organization. A failure to accurately match incentives to performance stifles initiative, and people do just enough to get by. Breaking free from this pattern is hard; a long history of seeing corporate initiatives ignored and then fade away tends to make people cynical. Often it's best to bring in an outsider to signal that this time things will be different. He or she will need to address every obstacle all at once: clarify decision rights; see to it that decisions stick; and reward people for sharing information and adding value, not for successfully negotiating corporate politics. If those steps are not taken, it's only a matter of time before the diseased elements of a passive-aggressive organization overwhelm the remaining healthy ones and drive the company into financial distress.

Passive Gas-Gap Heat Switches for Use in Low-Temperature Cryogenic Systems

NASA Technical Reports Server (NTRS)

Kimball, M. O.; Shirron, P. J.; Canavan, E. R.; Tuttle, J. G.; Jahromi, A. E.; Dipirro, M. J.; James, B. L.; Sampson, M. A.; Letmate, R. V.

2017-01-01

We present the current state of development in passive gas-gap heat switches. This type of switch does not require a separate heater to activate heat transfer but, instead, relies upon the warming of one end due to an intrinsic step in a thermodynamic cycle to raise a getter above a threshold temperature. Above this temperature sequestered gas is released to couple both sides of the switch. This enhances the thermodynamic efficiency of the system and reduces the complexity of the control system. Various gas mixtures and getter configurations will be presented.

Analysis on Target Detection and Classification in LTE Based Passive Forward Scattering Radar

PubMed Central

Raja Abdullah, Raja Syamsul Azmir; Abdul Aziz, Noor Hafizah; Abdul Rashid, Nur Emileen; Ahmad Salah, Asem; Hashim, Fazirulhisyam

2016-01-01

The passive bistatic radar (PBR) system can utilize the illuminator of opportunity to enhance radar capability. By utilizing the forward scattering technique and procedure into the specific mode of PBR can provide an improvement in target detection and classification. The system is known as passive Forward Scattering Radar (FSR). The passive FSR system can exploit the peculiar advantage of the enhancement in forward scatter radar cross section (FSRCS) for target detection. Thus, the aim of this paper is to show the feasibility of passive FSR for moving target detection and classification by experimental analysis and results. The signal source is coming from the latest technology of 4G Long-Term Evolution (LTE) base station. A detailed explanation on the passive FSR receiver circuit, the detection scheme and the classification algorithm are given. In addition, the proposed passive FSR circuit employs the self-mixing technique at the receiver; hence the synchronization signal from the transmitter is not required. The experimental results confirm the passive FSR system’s capability for ground target detection and classification. Furthermore, this paper illustrates the first classification result in the passive FSR system. The great potential in the passive FSR system provides a new research area in passive radar that can be used for diverse remote monitoring applications. PMID:27690051

Novel elastic protection against DDF failures in an enhanced software-defined SIEPON

NASA Astrophysics Data System (ADS)

Pakpahan, Andrew Fernando; Hwang, I.-Shyan; Yu, Yu-Ming; Hsu, Wu-Hsiao; Liem, Andrew Tanny; Nikoukar, AliAkbar

2017-07-01

Ever-increasing bandwidth demands on passive optical networks (PONs) are pushing the utilization of every fiber strand to its limit. This is mandating comprehensive protection until the end of the distribution drop fiber (DDF). Hence, it is important to provide refined protection with an advanced fault-protection architecture and recovery mechanism that is able to cope with various DDF failures. We propose a novel elastic protection against DDF failures that incorporates a software-defined networking (SDN) capability and a bus protection line to enhance the resiliency of the existing Service Interoperability in Ethernet Passive Optical Networks (SIEPON) system. We propose the addition of an integrated SDN controller and flow tables to the optical line terminal and optical network units (ONUs) in order to deliver various DDF protection scenarios. The proposed architecture enables flexible assignment of backup ONU(s) in pre/post-fault conditions depending on the PON traffic load. A transient backup ONU and multiple backup ONUs can be deployed in the pre-fault and post-fault scenarios, respectively. Our extensively discussed simulation results show that our proposed architecture provides better overall throughput and drop probability compared to the architecture with a fixed DDF protection mechanism. It does so while still maintaining overall QoS performance in terms of packet delay, mean jitter, packet loss, and throughput under various fault conditions.

Cascading failures in interdependent systems under a flow redistribution model

NASA Astrophysics Data System (ADS)

Zhang, Yingrui; Arenas, Alex; Yaǧan, Osman

2018-02-01

Robustness and cascading failures in interdependent systems has been an active research field in the past decade. However, most existing works use percolation-based models where only the largest component of each network remains functional throughout the cascade. Although suitable for communication networks, this assumption fails to capture the dependencies in systems carrying a flow (e.g., power systems, road transportation networks), where cascading failures are often triggered by redistribution of flows leading to overloading of lines. Here, we consider a model consisting of systems A and B with initial line loads and capacities given by {LA,i,CA ,i} i =1 n and {LB,i,CB ,i} i =1 n, respectively. When a line fails in system A , a fraction of its load is redistributed to alive lines in B , while remaining (1 -a ) fraction is redistributed equally among all functional lines in A ; a line failure in B is treated similarly with b giving the fraction to be redistributed to A . We give a thorough analysis of cascading failures of this model initiated by a random attack targeting p1 fraction of lines in A and p2 fraction in B . We show that (i) the model captures the real-world phenomenon of unexpected large scale cascades and exhibits interesting transition behavior: the final collapse is always first order, but it can be preceded by a sequence of first- and second-order transitions; (ii) network robustness tightly depends on the coupling coefficients a and b , and robustness is maximized at non-trivial a ,b values in general; (iii) unlike most existing models, interdependence has a multifaceted impact on system robustness in that interdependency can lead to an improved robustness for each individual network.

Cascading failures in interdependent systems under a flow redistribution model.

PubMed

Zhang, Yingrui; Arenas, Alex; Yağan, Osman

2018-02-01

Robustness and cascading failures in interdependent systems has been an active research field in the past decade. However, most existing works use percolation-based models where only the largest component of each network remains functional throughout the cascade. Although suitable for communication networks, this assumption fails to capture the dependencies in systems carrying a flow (e.g., power systems, road transportation networks), where cascading failures are often triggered by redistribution of flows leading to overloading of lines. Here, we consider a model consisting of systems A and B with initial line loads and capacities given by {L_{A,i},C_{A,i}}_{i=1}^{n} and {L_{B,i},C_{B,i}}_{i=1}^{n}, respectively. When a line fails in system A, a fraction of its load is redistributed to alive lines in B, while remaining (1-a) fraction is redistributed equally among all functional lines in A; a line failure in B is treated similarly with b giving the fraction to be redistributed to A. We give a thorough analysis of cascading failures of this model initiated by a random attack targeting p_{1} fraction of lines in A and p_{2} fraction in B. We show that (i) the model captures the real-world phenomenon of unexpected large scale cascades and exhibits interesting transition behavior: the final collapse is always first order, but it can be preceded by a sequence of first- and second-order transitions; (ii) network robustness tightly depends on the coupling coefficients a and b, and robustness is maximized at non-trivial a,b values in general; (iii) unlike most existing models, interdependence has a multifaceted impact on system robustness in that interdependency can lead to an improved robustness for each individual network.

Extended System Operations Studies for Automated Guideway Transit Systems : Plan for Task 5--DPM Failure Management

DOT National Transportation Integrated Search

1981-06-01

The purpose of Task 5 in the Extended System Operations Studies Project, DPM Failure Management, is to enhance the capabilities of the Downtown People Mover Simulation (DPMS) and the Discrete Event Simulation Model (DESM) by increasing the failure mo...

Failure detection and fault management techniques for flush airdata sensing systems

NASA Technical Reports Server (NTRS)

Whitmore, Stephen A.; Moes, Timothy R.; Leondes, Cornelius T.

1992-01-01

Methods based on chi-squared analysis are presented for detecting system and individual-port failures in the high-angle-of-attack flush airdata sensing system on the NASA F-18 High Alpha Research Vehicle. The HI-FADS hardware is introduced, and the aerodynamic model describes measured pressure in terms of dynamic pressure, angle of attack, angle of sideslip, and static pressure. Chi-squared analysis is described in the presentation of the concept for failure detection and fault management which includes nominal, iteration, and fault-management modes. A matrix of pressure orifices arranged in concentric circles on the nose of the aircraft indicate the parameters which are applied to the regression algorithms. The sensing techniques are applied to the F-18 flight data, and two examples are given of the computed angle-of-attack time histories. The failure-detection and fault-management techniques permit the matrix to be multiply redundant, and the chi-squared analysis is shown to be useful in the detection of failures.

Automatic Monitoring System Design and Failure Probability Analysis for River Dikes on Steep Channel

NASA Astrophysics Data System (ADS)

Chang, Yin-Lung; Lin, Yi-Jun; Tung, Yeou-Koung

2017-04-01

The purposes of this study includes: (1) design an automatic monitoring system for river dike; and (2) develop a framework which enables the determination of dike failure probabilities for various failure modes during a rainstorm. The historical dike failure data collected in this study indicate that most dikes in Taiwan collapsed under the 20-years return period discharge, which means the probability of dike failure is much higher than that of overtopping. We installed the dike monitoring system on the Chiu-She Dike which located on the middle stream of Dajia River, Taiwan. The system includes: (1) vertical distributed pore water pressure sensors in front of and behind the dike; (2) Time Domain Reflectometry (TDR) to measure the displacement of dike; (3) wireless floating device to measure the scouring depth at the toe of dike; and (4) water level gauge. The monitoring system recorded the variation of pore pressure inside the Chiu-She Dike and the scouring depth during Typhoon Megi. The recorded data showed that the highest groundwater level insides the dike occurred 15 hours after the peak discharge. We developed a framework which accounts for the uncertainties from return period discharge, Manning's n, scouring depth, soil cohesion, and friction angle and enables the determination of dike failure probabilities for various failure modes such as overtopping, surface erosion, mass failure, toe sliding and overturning. The framework was applied to Chiu-She, Feng-Chou, and Ke-Chuang Dikes on Dajia River. The results indicate that the toe sliding or overturning has the highest probability than other failure modes. Furthermore, the overall failure probability (integrate different failure modes) reaches 50% under 10-years return period flood which agrees with the historical failure data for the study reaches.

Geochemistry of rare earth elements in a passive treatment system built for acid mine drainage remediation.

PubMed

Prudêncio, Maria Isabel; Valente, Teresa; Marques, Rosa; Sequeira Braga, Maria Amália; Pamplona, Jorge

2015-11-01

Rare earth elements (REE) were used to assess attenuation processes in a passive system for acid mine drainage treatment (Jales, Portugal). Hydrochemical parameters and REE contents in water, soils and sediments were obtained along the treatment system, after summer and winter. A decrease of REE contents in the water resulting from the interaction with limestone after summer occurs; in the wetlands REE are significantly released by the soil particles to the water. After winter, a higher water dynamics favors the AMD treatment effectiveness and performance since REE contents decrease along the system; La and Ce are preferentially sequestered by ochre sludge but released to the water in the wetlands, influencing the REE pattern of the creek water. Thus, REE fractionation occurs in the passive treatment systems and can be used as tracer to follow up and understand the geochemical processes that promote the remediation of AMD. Copyright © 2015 Elsevier Ltd. All rights reserved.

Passive decay heat removal system for water-cooled nuclear reactors

DOEpatents

Forsberg, Charles W.

1991-01-01

A passive decay-heat removal system for a water-cooled nuclear reactor employs a closed heat transfer loop having heat-exchanging coils inside an open-topped, insulated box located inside the reactor vessel, below its normal water level, in communication with a condenser located outside of containment and exposed to the atmosphere. The heat transfer loop is located such that the evaporator is in a position where, when the water level drops in the reactor, it will become exposed to steam. Vapor produced in the evaporator passes upward to the condenser above the normal water level. In operation, condensation in the condenser removes heat from the system, and the condensed liquid is returned to the evaporator. The system is disposed such that during normal reactor operations where the water level is at its usual position, very little heat will be removed from the system, but during emergency, low water level conditions, substantial amounts of decay heat will be removed.

Assessment of Integrated Pedestrian Protection Systems with Autonomous Emergency Braking (AEB) and Passive Safety Components.

PubMed

Edwards, Mervyn; Nathanson, Andrew; Carroll, Jolyon; Wisch, Marcus; Zander, Oliver; Lubbe, Nils

2015-01-01

Autonomous emergency braking (AEB) systems fitted to cars for pedestrians have been predicted to offer substantial benefit. On this basis, consumer rating programs-for example, the European New Car Assessment Programme (Euro NCAP)-are developing rating schemes to encourage fitment of these systems. One of the questions that needs to be answered to do this fully is how the assessment of the speed reduction offered by the AEB is integrated with the current assessment of the passive safety for mitigation of pedestrian injury. Ideally, this should be done on a benefit-related basis. The objective of this research was to develop a benefit-based methodology for assessment of integrated pedestrian protection systems with AEB and passive safety components. The method should include weighting procedures to ensure that it represents injury patterns from accident data and replicates an independently estimated benefit of AEB. A methodology has been developed to calculate the expected societal cost of pedestrian injuries, assuming that all pedestrians in the target population (i.e., pedestrians impacted by the front of a passenger car) are impacted by the car being assessed, taking into account the impact speed reduction offered by the car's AEB (if fitted) and the passive safety protection offered by the car's frontal structure. For rating purposes, the cost for the assessed car is normalized by comparing it to the cost calculated for a reference car. The speed reductions measured in AEB tests are used to determine the speed at which each pedestrian in the target population will be impacted. Injury probabilities for each impact are then calculated using the results from Euro NCAP pedestrian impactor tests and injury risk curves. These injury probabilities are converted into cost using "harm"-type costs for the body regions tested. These costs are weighted and summed. Weighting factors were determined using accident data from Germany and Great Britain and an independently

Global left atrial failure in heart failure.

PubMed

Triposkiadis, Filippos; Pieske, Burkert; Butler, Javed; Parissis, John; Giamouzis, Gregory; Skoularigis, John; Brutsaert, Dirk; Boudoulas, Harisios

2016-11-01

The left atrium plays an important role in the maintenance of cardiovascular and neurohumoral homeostasis in heart failure. However, with progressive left ventricular dysfunction, left atrial (LA) dilation and mechanical failure develop, which frequently culminate in atrial fibrillation. Moreover, LA mechanical failure is accompanied by LA endocrine failure [deficient atrial natriuretic peptide (ANP) processing-synthesis/development of ANP resistance) and LA regulatory failure (dominance of sympathetic nervous system excitatory mechanisms, excessive vasopressin release) contributing to neurohumoral overactivity, vasoconstriction, and volume overload (global LA failure). The purpose of the present review is to describe the characteristics and emphasize the clinical significance of global LA failure in patients with heart failure. © 2016 The Authors. European Journal of Heart Failure © 2016 European Society of Cardiology.

Implant experience with an implantable hemodynamic monitor for the management of symptomatic heart failure.

PubMed

Steinhaus, David; Reynolds, Dwight W; Gadler, Fredrik; Kay, G Neal; Hess, Mike F; Bennett, Tom

2005-08-01

Management of congestive heart failure is a serious public health problem. The use of implantable hemodynamic monitors (IHMs) may assist in this management by providing continuous ambulatory filling pressure status for optimal volume management. The Chronicle system includes an implanted monitor, a pressure sensor lead with passive fixation, an external pressure reference (EPR), and data retrieval and viewing components. The tip of the lead is placed near the right ventricular outflow tract to minimize risk of sensor tissue encapsulation. Implant technique and lead placement is similar to that of a permanent pacemaker. After the system had been successfully implanted in 148 patients, the type and frequency of implant-related adverse events were similar to a single-chamber pacemaker implant. R-wave amplitude was 15.2 +/- 6.7 mV and the pressure waveform signal was acceptable in all but two patients in whom presence of artifacts required lead repositioning. Implant procedure time was not influenced by experience, remaining constant throughout the study. Based on this evaluation, permanent placement of an IHM in symptomatic heart failure patients is technically feasible. Further investigation is warranted to evaluate the use of the continuous hemodynamic data in management of heart failure patients.

Development of Passive Fuel Cell Thermal Management Technology

NASA Technical Reports Server (NTRS)

Burke, Kenneth A.; Jakupca, Ian; Colozza, Anthony

2011-01-01

The NASA Glenn Research Center is developing advanced passive thermal management technology to reduce the mass and improve the reliability of space fuel cell systems for the NASA exploration program. The passive thermal management system relies on heat conduction within the cooling plate to move the heat from the central portion of the cell stack out to the edges of the fuel cell stack rather than using a pumped loop cooling system to convectively remove the heat. Using the passive approach eliminates the need for a coolant pump and other cooling loop components which reduces fuel cell system mass and improves overall system reliability. Previous analysis had identified that low density, ultra-high thermal conductivity materials would be needed for the cooling plates in order to achieve the desired reductions in mass and the highly uniform thermal heat sink for each cell within a fuel cell stack. A pyrolytic graphite material was identified and fabricated into a thin plate using different methods. Also a development project with Thermacore, Inc. resulted in a planar heat pipe. Thermal conductivity tests were done using these materials. The results indicated that lightweight passive fuel cell cooling is feasible.

Passive vs. active safety belt systems in Volkswagen rabbits : a comparison of owner use habits and attitudes

DOT National Transportation Integrated Search

1976-08-01

The overall objective of this research is to measure usage of, and attitudes toward, the passive restraint system, compared with the active restraint system on 1975 model year Volkswagen Rabbits. Methods used to carry out the research include: Interv...

Decomposition-Based Failure Mode Identification Method for Risk-Free Design of Large Systems

NASA Technical Reports Server (NTRS)

Tumer, Irem Y.; Stone, Robert B.; Roberts, Rory A.; Clancy, Daniel (Technical Monitor)

2002-01-01

When designing products, it is crucial to assure failure and risk-free operation in the intended operating environment. Failures are typically studied and eliminated as much as possible during the early stages of design. The few failures that go undetected result in unacceptable damage and losses in high-risk applications where public safety is of concern. Published NASA and NTSB accident reports point to a variety of components identified as sources of failures in the reported cases. In previous work, data from these reports were processed and placed in matrix form for all the system components and failure modes encountered, and then manipulated using matrix methods to determine similarities between the different components and failure modes. In this paper, these matrices are represented in the form of a linear combination of failures modes, mathematically formed using Principal Components Analysis (PCA) decomposition. The PCA decomposition results in a low-dimensionality representation of all failure modes and components of interest, represented in a transformed coordinate system. Such a representation opens the way for efficient pattern analysis and prediction of failure modes with highest potential risks on the final product, rather than making decisions based on the large space of component and failure mode data. The mathematics of the proposed method are explained first using a simple example problem. The method is then applied to component failure data gathered from helicopter, accident reports to demonstrate its potential.

Failure analysis and modeling of a multicomputer system. M.S. Thesis

NASA Technical Reports Server (NTRS)

Subramani, Sujatha Srinivasan

1990-01-01

This thesis describes the results of an extensive measurement-based analysis of real error data collected from a 7-machine DEC VaxCluster multicomputer system. In addition to evaluating basic system error and failure characteristics, we develop reward models to analyze the impact of failures and errors on the system. The results show that, although 98 percent of errors in the shared resources recover, they result in 48 percent of all system failures. The analysis of rewards shows that the expected reward rate for the VaxCluster decreases to 0.5 in 100 days for a 3 out of 7 model, which is well over a 100 times that for a 7-out-of-7 model. A comparison of the reward rates for a range of k-out-of-n models indicates that the maximum increase in reward rate (0.25) occurs in going from the 6-out-of-7 model to the 5-out-of-7 model. The analysis also shows that software errors have the lowest reward (0.2 vs. 0.91 for network errors). The large loss in reward rate for software errors is due to the fact that a large proportion (94 percent) of software errors lead to failure. In comparison, the high reward rate for network errors is due to fast recovery from a majority of these errors (median recovery duration is 0 seconds).

Virtual Passive Controller for Robot Systems Using Joint Torque Sensors

NASA Technical Reports Server (NTRS)

Aldridge, Hal A.; Juang, Jer-Nan

1997-01-01

This paper presents a control method based on virtual passive dynamic control that will stabilize a robot manipulator using joint torque sensors and a simple joint model. The method does not require joint position or velocity feedback for stabilization. The proposed control method is stable in the sense of Lyaponov. The control method was implemented on several joints of a laboratory robot. The controller showed good stability robustness to system parameter error and to the exclusion of nonlinear dynamic effects on the joints. The controller enhanced position tracking performance and, in the absence of position control, dissipated joint energy.

The replacement of dry heat in generic reliability assurance requirements for passive optical components

NASA Astrophysics Data System (ADS)

Ren, Xusheng; Qian, Longsheng; Zhang, Guiyan

2005-12-01

According to Generic Reliability Assurance Requirements for Passive Optical Components GR-1221-CORE (Issue 2, January 1999), reliability determination test of different kinds of passive optical components which using in uncontrolled environments is taken. The test condition of High Temperature Storage Test (Dry Test) and Damp Test is in below sheet. Except for humidity condition, all is same. In order to save test time and cost, after a sires of contrast tests, the replacement of Dry Heat is discussed. Controlling the Failure mechanism of dry heat and damp heat of passive optical components, the contrast test of dry heat and damp heat for passive optical components (include DWDM, CWDM, Coupler, Isolator, mini Isolator) is taken. The test result of isolator is listed. Telcordia test not only test the reliability of the passive optical components, but also test the patience of the experimenter. The cost of Telcordia test in money, manpower and material resources, especially in time is heavy burden for the company. After a series of tests, we can find that Damp heat could factually test the reliability of passive optical components, and equipment manufacturer in accord with component manufacture could omit the dry heat test if damp heat test is taken first and passed.

Explosive Event in MON-3 Oxidizer System Resulting from Pressure Transducer Failure

NASA Technical Reports Server (NTRS)

Baker, David L.; Reynolds, Michael; Anderson, John

2006-01-01

In 2003, a Druck(Registered Trademark) pressure transducer failed catastrophically in a test system circulating nitrogen tetroxide at NASA Johnson Space Center White Sands Test Facility. The cause of the explosion was not immediately obvious since the wetted areas of the pressure transducer were constructed of materials compatible with nitrogen tetroxide. Chemical analysis of the resulting residue and a materials analysis of the diaphragm and its weld zones were used to determine the chain of events that led to the catastrophic failure. Due to excessive dynamic pressure loading in the test system, the diaphragm in the pressure transducer suffered cyclic failure and allowed the silicon oil located behind the isolation diaphragm to mix with the nitrogen tetroxide. The reaction between these two chemicals formed a combination of 2,4-di and 2,4,6-trinitrophenol, which are shock sensitive explosives that caused the failure of the pressure transducer. Further research indicated numerous manufacturers offer similar pressure transducers with silicone oil separated from the test fluid by a thin stainless steel isolation diaphragm. Caution must be exercised when purchasing a pressure transducer for a particular system to avoid costly failures and test system contamination.

Active and passive electrical and seismic time-lapse monitoring of earthen embankments

NASA Astrophysics Data System (ADS)

Rittgers, Justin Bradley

In this dissertation, I present research involving the application of active and passive geophysical data collection, data assimilation, and inverse modeling for the purpose of earthen embankment infrastructure assessment. Throughout the dissertation, I identify several data characteristics, and several challenges intrinsic to characterization and imaging of earthen embankments and anomalous seepage phenomena, from both a static and time-lapse geophysical monitoring perspective. I begin with the presentation of a field study conducted on a seeping earthen dam, involving static and independent inversions of active tomography data sets, and self-potential modeling of fluid flow within a confined aquifer. Additionally, I present results of active and passive time-lapse geophysical monitoring conducted during two meso-scale laboratory experiments involving the failure and self-healing of embankment filter materials via induced vertical cracking. Identified data signatures and trends, as well as 4D inversion results, are discussed as an underlying motivation for conducting subsequent research. Next, I present a new 4D acoustic emissions source localization algorithm that is applied to passive seismic monitoring data collected during a full-scale embankment failure test. Acoustic emissions localization results are then used to help spatially constrain 4D inversion of collocated self-potential monitoring data. I then turn to time-lapse joint inversion of active tomographic data sets applied to the characterization and monitoring of earthen embankments. Here, I develop a new technique for applying spatiotemporally varying structural joint inversion constraints. The new technique, referred to as Automatic Joint Constraints (AJC), is first demonstrated on a synthetic 2D joint model space, and is then applied to real geophysical monitoring data sets collected during a full-scale earthen embankment piping-failure test. Finally, I discuss some non-technical issues related to

Optimization of Passive Coherent Receiver System Placement

DTIC Science & Technology

2013-09-01

spheroid object with a constant radar cross section (RCS). Additionally, the receiver and transmitters are assumed to be notional isotropic antennae...software- defined radio for equatorial plasma instability studies,” Radio Science, vol. 48, pp. 1–11. Aug. 2013. [2] P. C. Zhang and B. Y. Li, “Passive

Passivity-Based Control for Two-Wheeled Robot Stabilization

NASA Astrophysics Data System (ADS)

Uddin, Nur; Aryo Nugroho, Teguh; Agung Pramudito, Wahyu

2018-04-01

A passivity-based control system design for two-wheeled robot (TWR) stabilization is presented. A TWR is a statically-unstable non-linear system. A control system is applied to actively stabilize the TWR. Passivity-based control method is applied to design the control system. The design results in a state feedback control law that makes the TWR closed loop system globally asymptotically stable (GAS). The GAS is proven mathematically. The TWR stabilization is demonstrated through computer simulation. The simulation results show that the designed control system is able to stabilize the TWR.

A geometric approach to failure detection and identification in linear systems

NASA Technical Reports Server (NTRS)

Massoumnia, M. A.

1986-01-01

Using concepts of (C,A)-invariant and unobservability (complementary observability) subspaces, a geometric formulation of the failure detection and identification filter problem is stated. Using these geometric concepts, it is shown that it is possible to design a causal linear time-invariant processor that can be used to detect and uniquely identify a component failure in a linear time-invariant system, assuming: (1) The components can fail simultaneously, and (2) The components can fail only one at a time. In addition, a geometric formulation of Beard's failure detection filter problem is stated. This new formulation completely clarifies of output separability and mutual detectability introduced by Beard and also exploits the dual relationship between a restricted version of the failure detection and identification problem and the control decoupling problem. Moreover, the frequency domain interpretation of the results is used to relate the concepts of failure sensitive observers with the generalized parity relations introduced by Chow. This interpretation unifies the various failure detection and identification concepts and design procedures.

Wetland-based passive treatment systems for gold ore processing effluents containing residual cyanide, metals and nitrogen species.

PubMed

Alvarez, R; Ordóñez, A; Loredo, J; Younger, P L

2013-10-01

Gold extraction operations generate a variety of wastes requiring responsible disposal in compliance with current environmental regulations. During recent decades, increased emphasis has been placed on effluent control and treatment, in order to avoid the threat to the environment posed by toxic constituents. In many modern gold mining and ore processing operations, cyanide species are of most immediate concern. Given that natural degradation processes are known to reduce the toxicity of cyanide over time, trials have been made at laboratory and field scales into the feasibility of using wetland-based passive systems as low-cost and environmentally friendly methods for long-term treatment of leachates from closed gold mine tailing disposal facilities. Laboratory experiments on discrete aerobic and anaerobic treatment units supported the development of design parameters for the construction of a field-scale passive system at a gold mine site in northern Spain. An in situ pilot-scale wetland treatment system was designed, constructed and monitored over a nine-month period. Overall, the results suggest that compost-based constructed wetlands are capable of detoxifying cyanidation effluents, removing about 21.6% of dissolved cyanide and 98% of Cu, as well as nitrite and nitrate. Wetland-based passive systems can therefore be considered as a viable technology for removal of residual concentrations of cyanide from leachates emanating from closed gold mine tailing disposal facilities.

Passive and active floating torque during swimming.

PubMed

Kjendlie, Per-Ludvik; Stallman, Robert Keig; Stray-Gundersen, James

2004-10-01

The purpose of this study was to examine the effect of passive underwater torque on active body angle with the horizontal during front crawl swimming and to assess the effect of body size on passive torque and active body angle. Additionally, the effects of passive torque, body angle and hydrostatic lift on maximal sprinting performance were addressed. Ten boys [aged 11.7 (0.8) years] and 12 male adult [aged 21.4 (3.7) years] swimmers volunteered to participate. Their body angle with the horizontal was measured at maximal velocity, and at two submaximal velocities using an underwater video camera system. Passive torque and hydrostatic lift were measured during an underwater weighing procedure, and the center of mass and center of volume were determined. The results showed that passive torque correlated significantly with the body angle at a velocity 63% of v(max) ( alpha(63) r=-0.57), and that size-normalized passive torque correlated significantly with the alpha(63) and alpha(77) (77% of v(max)) with r=-0.59 and r=-0.54 respectively. Hydrostatic lift correlated with alpha(63) with r=-0.45. The negative correlation coefficients are suggested to be due to the adults having learned to overcome passive torque when swimming at submaximal velocities by correcting their body angle. It is concluded that at higher velocities the passive torque and hydrostatic lift do not influence body angle during swimming. At a velocity of 63% of v(max), hydrostatic lift and passive torque influences body angle. Passive torque and size-normalized passive torque increases with body size. When corrected for body size, hydrostatic lift and passive torque did not influence the maximal sprinting velocity.

Thermomechanical Controls on the Success and Failure of Continental Rift Systems

NASA Astrophysics Data System (ADS)

Brune, S.

2017-12-01

Studies of long-term continental rift evolution are often biased towards rifts that succeed in breaking the continent like the North Atlantic, South China Sea, or South Atlantic rifts. However there are many prominent rift systems on Earth where activity stopped before the formation of a new ocean basin such as the North Sea, the West and Central African Rifts, or the West Antarctic Rift System. The factors controlling the success and failure of rifts can be divided in two groups: (1) Intrinsic processes - for instance frictional weakening, lithospheric thinning, shear heating or the strain-dependent growth of rift strength by replacing weak crust with strong mantle. (2) External processes - such as a change of plate divergence rate, the waning of a far-field driving force, or the arrival of a mantle plume. Here I use numerical and analytical modeling to investigate the role of these processes for the success and failure of rift systems. These models show that a change of plate divergence rate under constant force extension is controlled by the non-linearity of lithospheric materials. For successful rifts, a strong increase in divergence velocity can be expected to take place within few million years, a prediction that agrees with independent plate tectonic reconstructions of major Mesozoic and Cenozoic ocean-forming rift systems. Another model prediction is that oblique rifting is mechanically favored over orthogonal rifting, which means that simultaneous deformation within neighboring rift systems of different obliquity and otherwise identical properties will lead to success and failure of the more and less oblique rift, respectively. This can be exemplified by the Cretaceous activity within the Equatorial Atlantic and the West African Rifts that lead to the formation of a highly oblique oceanic spreading center and the failure of the West African Rift System. While in nature the circumstances of rift success or failure may be manifold, simplified numerical and

Progress in passive solar energy systems. Volume 8. Part 1

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

Hayes, J.; Andrejko, D.A.

1983-01-01

This book presents the papers given at a conference sponsored by the US DOE, the Solar Energy Research Institute, SolarVision, Inc., and the Southern California Solar Energy Society. The topics considered at the conference included sizing solar energy systems for agricultural applications, a farm scale ethanol production plant, the EEC wind energy RandD program, the passive solar performance assessment of an earth-sheltered house, the ARCO 1 MW photovoltaic power plant, the performance of a dendritic web photovoltaic module, second generation point focused concentrators, linear fresnel lens concentrating photovoltaic collectors, photovoltaic conversion efficiency, amorphous silicon thin film solar cells, a photovoltaicmore » system for a shopping center, photovoltaic power generation for the utility industry, spectral solar radiation, and the analysis of insolation data.« less

Systems approach to walk-off problems for dish-type solar thermal power systems

NASA Technical Reports Server (NTRS)

Jaffe, L. D.; Levin, R. R.; Moynihan, P. I.; Nesmith, B. J.; Owen, W. A.; Roschke, E. J.; Starkey, D. J.; Thostesen, T. O.

1983-01-01

'Walk-off' in a dish-type solar thermal power system is a failure situation in which the concentrator remains fixed while the spot of concentrated sunlight slowly moves across the face of the receiver. The intense local heating may damage the receiver and nearby equipment. Passive protection has advantages in minimizing damage, but in a fully passive design the receiver must be able to withstand full solar input with no forced fluid circulation during the walk-off. An active walk-off emergency subsystem may include an emergency detrack or defocus mechanism or sun-blocking device, emergency power, sensors and logic to detect the emergency and initiate protective action, and cooling or passive protection of emergency and non-emergency components. Each of these elements is discussed and evaluated in the paper.

Disinfection of Spacecraft Potable Water Systems by Passivation with Ionic Silver

NASA Technical Reports Server (NTRS)

Birmele, Michele N.; McCoy, LaShelle e.; Roberts, Michael S.

2011-01-01

Microbial growth is common on wetted surfaces in spacecraft environmental control and life support systems despite the use of chemical and physical disinfection methods. Advanced control technologies are needed to limit microorganisms and increase the reliability of life support systems required for long-duration human missions. Silver ions and compounds are widely used as antimicrobial agents for medical applications and continue to be used as a residual biocide in some spacecraft water systems. The National Aeronautics and Space Administration (NASA) has identified silver fluoride for use in the potable water system on the next generation spacecraft. Due to ionic interactions between silver fluoride in solution and wetted metallic surfaces, ionic silver is rapidly depleted from solution and loses its antimicrobial efficacy over time. This report describes research to prolong the antimicrobial efficacy of ionic silver by maintaining its solubility. Three types of metal coupons (lnconel 718, Stainless Steel 316, and Titanium 6AI-4V) used in spacecraft potable water systems were exposed to either a continuous flow of water amended with 0.4 mg/L ionic silver fluoride or to a static, pre-treatment passivation in 50 mg/L ionic silver fluoride with or without a surface oxidation pre-treatment. Coupons were then challenged in a high-shear, CDC bioreactor (BioSurface Technologies) by exposure to six bacteria previously isolated from spacecraft potable water systems. Continuous exposure to 0.4 mg/L ionic silver over the course of 24 hours during the flow phase resulted in a >7-log reduction. The residual effect of a 24-hour passivation treatment in 50 mg/L of ionic silver resulted in a >3-log reduction, whereas a two-week treatment resulted in a >4-log reduction. Results indicate that 0.4 mg/L ionic silver is an effective biocide against many bacteria and that a prepassivation of metal surfaces with silver can provide additional microbial control.

Effectiveness of a passive-active vibration isolation system with actuator constraints

NASA Astrophysics Data System (ADS)

Sun, Lingling; Sun, Wei; Song, Kongjie; Hansen, Colin H.

2014-05-01

In the prediction of active vibration isolation performance, control force requirements were ignored in previous work. This may limit the realization of theoretically predicted isolation performance if control force of large magnitude cannot be supplied by actuators. The behavior of a feed-forward active isolation system subjected to actuator output constraints is investigated. Distributed parameter models are developed to analyze the system response, and to produce a transfer matrix for the design of an integrated passive-active isolation system. Cost functions comprising a combination of the vibration transmission energy and the sum of the squared control forces are proposed. The example system considered is a rigid body connected to a simply supported plate via two passive-active isolation mounts. Vertical and transverse forces as well as a rotational moment are applied at the rigid body, and resonances excited in elastic mounts and the supporting plate are analyzed. The overall isolation performance is evaluated by numerical simulation. The simulation results are then compared with those obtained using unconstrained control strategies. In addition, the effects of waves in elastic mounts are analyzed. It is shown that the control strategies which rely on unconstrained actuator outputs may give substantial power transmission reductions over a wide frequency range, but also require large control force amplitudes to control excited vibration modes of the system. Expected power transmission reductions for modified control strategies that incorporate constrained actuator outputs are considerably less than typical reductions with unconstrained actuator outputs. In the frequency range in which rigid body modes are present, the control strategies can only achieve 5-10 dB power transmission reduction, when control forces are constrained to be the same order of the magnitude as the primary vertical force. The resonances of the elastic mounts result in a notable increase

Plant Line Trial Evaluation of Viable Non-Chromium Passivation Systems for Electrolytin Tinplate, ETP (TRP 9911)

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

John A. Sinsel

2003-06-30

Plant trial evaluations have been completed for two zirconium-based, non-chromium passivation systems previously identified as possible alternatives to cathodic dichromate (CDC) passivation for electrolytic tinplate (ETP). These trials were done on a commercial electrolytic tin plating line at Weirton Steel and extensive evaluations of the materials resulting from these trials have been completed. All this was accomplished as a collaborative effort under the AISI Technology Roadmap Program and was executed by seven North American Tin Mill Products producers [Bethlehem Steel (now acquired by International Steel Group (ISG)), Dofasco Inc., National Steel (now acquired by U.S. Steel), U.S. Steel, USS-Posco, Weirtonmore » Steel, and Wheeling-Pittsburgh Steel] with funding partially from the Department of Energy (DOE) and partially on an equal cost sharing basis among project participants. The initial phases of this project involved optimization of application procedures for the non-chromium systems in the laboratories at Bethlehem Steel and Betz Dearborn followed by extensive testing with various lacquer formulations and food simulants in the laboratories at Valspar and PPG. Work was also completed at Dofasco and Weirton Steel to develop methods to prevent precipitation of insoluble solids as a function of time from the zirconate system. The results of this testing indicated that sulfide staining characteristics for the non-chromium passivation systems could be minimized but not totally eliminated and neither system was found to perform quite as good, in this respect, as the standard CDC system. As for the stability of zirconate treatment, a method was developed to stabilize this system for a sufficient period of time to conduct plant trial evaluations but, working with a major supplier of zirconium orthosulfate, a method for long term stabilization is still under development.« less

Surface passivation for tight-binding calculations of covalent solids.

PubMed

Bernstein, N

2007-07-04

Simulation of a cluster representing a finite portion of a larger covalently bonded system requires the passivation of the cluster surface. We compute the effects of an explicit hybrid orbital passivation (EHOP) on the atomic structure in a model bulk, three-dimensional, narrow gap semiconductor, which is very different from the wide gap, quasi-one-dimensional organic molecules where most passivation schemes have been studied in detail. The EHOP approach is directly applicable to minimal atomic orbital basis methods such as tight-binding. Each broken bond is passivated by a hybrid created from an explicitly expressed linear combination of basis orbitals, chosen to represent the contribution of the missing neighbour, e.g. a sp(3) hybrid for a single bond. The method is tested by computing the forces on atoms near a point defect as a function of cluster geometry. We show that, compared to alternatives such as pseudo-hydrogen passivation, the force on an atom converges to the correct bulk limit more quickly as a function of cluster radius, and that the force is more stable with respect to perturbations in the position of the cluster centre. The EHOP method also obviates the need for parameterizing the interactions between the system atoms and the passivating atoms. The method is useful for cluster calculations of non-periodic defects in large systems and for hybrid schemes that simulate large systems by treating finite regions with a quantum-mechanical model, coupled to an interatomic potential description of the rest of the system.

Surface passivation for tight-binding calculations of covalent solids

NASA Astrophysics Data System (ADS)

Bernstein, N.

2007-07-01

Simulation of a cluster representing a finite portion of a larger covalently bonded system requires the passivation of the cluster surface. We compute the effects of an explicit hybrid orbital passivation (EHOP) on the atomic structure in a model bulk, three-dimensional, narrow gap semiconductor, which is very different from the wide gap, quasi-one-dimensional organic molecules where most passivation schemes have been studied in detail. The EHOP approach is directly applicable to minimal atomic orbital basis methods such as tight-binding. Each broken bond is passivated by a hybrid created from an explicitly expressed linear combination of basis orbitals, chosen to represent the contribution of the missing neighbour, e.g. a sp3 hybrid for a single bond. The method is tested by computing the forces on atoms near a point defect as a function of cluster geometry. We show that, compared to alternatives such as pseudo-hydrogen passivation, the force on an atom converges to the correct bulk limit more quickly as a function of cluster radius, and that the force is more stable with respect to perturbations in the position of the cluster centre. The EHOP method also obviates the need for parameterizing the interactions between the system atoms and the passivating atoms. The method is useful for cluster calculations of non-periodic defects in large systems and for hybrid schemes that simulate large systems by treating finite regions with a quantum-mechanical model, coupled to an interatomic potential description of the rest of the system.

Combining Passive Thermography and Acoustic Emission for Large Area Fatigue Damage Growth Assessment of a Composite Structure

NASA Technical Reports Server (NTRS)

Zalameda, Joseph N.; Horne, Michael R.; Madaras, Eric I.; Burke, Eric R.

2016-01-01

Passive thermography and acoustic emission data were obtained for improved real time damage detection during fatigue loading. A strong positive correlation was demonstrated between acoustic energy event location and thermal heating, especially if the structure under load was nearing ultimate failure. An image processing routine was developed to map the acoustic emission data onto the thermal imagery. This required removing optical barrel distortion and angular rotation from the thermal data. The acoustic emission data were then mapped onto thermal data, revealing the cluster of acoustic emission event locations around the thermal signatures of interest. By combining both techniques, progression of damage growth is confirmed and areas of failure are identified. This technology provides improved real time inspections of advanced composite structures during fatigue testing.Keywords: Thermal nondestructive evaluation, fatigue damage detection, aerospace composite inspection, acoustic emission, passive thermography

End-of-Mission Passivation: Successes and Challenges

NASA Technical Reports Server (NTRS)

Johnson, Nicholas; Matney, Mark

2012-01-01

The passivation of spacecraft and launch vehicle orbital stages at end-of-mission has been a principal space debris mitigation measure world-wide since the 1980 s. Space vehicle passivation includes the removal of stored energies, especially those associated with propulsion and electrical power systems. Prior to 2007 the breakup of non-functioning, non-passivated space vehicles was the major source of hazardous debris in Earth orbit. The United Nations and the Inter-Agency Space Debris Coordination Committee have both included passivation in their formal space debris mitigation guidelines. This often simple countermeasure has been adopted by many spacefaring countries and organizations and has undoubtedly prevented numerous major satellite breakups. For some existing space vehicle designs, passivation requires changes in hardware, software, and/or operational procedures. Questions about the permissible degree of passivation for both current and future space vehicles have arisen and are addressed herein. An important element to be considered is the potentially long period in which the space vehicle will remain in orbit, i.e., up to 25 years after mission termination in LEO and for centuries in orbits above LEO. Finally, the issue of passivation of space vehicles which have failed prematurely is addressed.

Thermal-hydraulic modeling needs for passive reactors

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

Kelly, J.M.

1997-07-01

The U.S. Nuclear Regulatory Commission has received an application for design certification from the Westinghouse Electric Corporation for an Advanced Light Water Reactor design known as the AP600. As part of the design certification process, the USNRC uses its thermal-hydraulic system analysis codes to independently audit the vendor calculations. The focus of this effort has been the small break LOCA transients that rely upon the passive safety features of the design to depressurize the primary system sufficiently so that gravity driven injection can provide a stable source for long term cooling. Of course, large break LOCAs have also been considered,more » but as the involved phenomena do not appear to be appreciably different from those of current plants, they were not discussed in this paper. Although the SBLOCA scenario does not appear to threaten core coolability - indeed, heatup is not even expected to occur - there have been concerns as to the performance of the passive safety systems. For example, the passive systems drive flows with small heads, consequently requiring more precision in the analysis compared to active systems methods for passive plants as compared to current plants with active systems. For the analysis of SBLOCAs and operating transients, the USNRC uses the RELAP5 thermal-hydraulic system analysis code. To assure the applicability of RELAP5 to the analysis of these transients for the AP600 design, a four year long program of code development and assessment has been undertaken.« less

Space-for-time substitution and the evolution of submarine canyons in a passive, progradational margin.

NASA Astrophysics Data System (ADS)

Micallef, Aaron; Ribó, Marta; Canals, Miquel; Puig, Pere; Lastras, Galderic; Tubau, Xavier

2013-04-01

40% of submarine canyons worldwide are located in passive margins, where they constitute preferential conduits of sediment and biodiversity hotspots. Recent studies have presented evidence that submarine canyons incising passive, progradational margins can co-evolve with the adjacent continental slope during long-term margin construction. The stages of submarine canyon initiation and their development into a mature canyon-channel system are still poorly constrained, however, which is problematic when attempting to reconstruct the development of passive continental margins. In this study we analyse multibeam echosounder and seismic reflection data from the southern Ebro margin (western Mediterranean Sea) to document the stages through which a first-order gully develops into a mature, shelf-breaching canyon and, finally, into a canyon-channel system. This morphological evolution allows the application of a space-for-time substitution approach. Initial gully growth on the continental slope takes place via incision and downslope elongation, with limited upslope head retreat. Gravity flows are the main driver of canyon evolution, whereas slope failures are the main agent of erosion; they control the extent of valley widening, promote tributary development, and their influence becomes more significant with time. Breaching of the continental shelf by a canyon results in higher water/sediment loads that enhance canyon development, particularly in the upper reaches. Connection of the canyon head with a paleo-river changes evolution dynamics significantly, promoting development of a channel and formation of depositional landforms. Morphometric analyses demonstrate that canyons develop into geometrically self-similar systems that approach steady-state and higher drainage efficiency. Canyon activity in the southern Ebro margin is pulsating and enhanced during sea level lowstands. Rapid sedimentation by extension of the palaeo-Millars River into the outermost shelf and upper

Evolving Systems: Adaptive Key Component Control and Inheritance of Passivity and Dissipativity

NASA Technical Reports Server (NTRS)

Frost, S. A.; Balas, M. J.

2010-01-01

We propose a new framework called Evolving Systems to describe the self-assembly, or autonomous assembly, of actively controlled dynamical subsystems into an Evolved System with a higher purpose. Autonomous assembly of large, complex flexible structures in space is a target application for Evolving Systems. A critical requirement for autonomous assembling structures is that they remain stable during and after assembly. The fundamental topic of inheritance of stability, dissipativity, and passivity in Evolving Systems is the primary focus of this research. In this paper, we develop an adaptive key component controller to restore stability in Nonlinear Evolving Systems that would otherwise fail to inherit the stability traits of their components. We provide sufficient conditions for the use of this novel control method and demonstrate its use on an illustrative example.

Investigation of pump and pump switch failures in rainwater harvesting systems

NASA Astrophysics Data System (ADS)

Moglia, Magnus; Gan, Kein; Delbridge, Nathan; Sharma, Ashok K.; Tjandraatmadja, Grace

2016-07-01

Rainwater harvesting is an important technology in cities that can contribute to a number of functions, such as sustainable water management in the face of demand growth and drought as well as the detention of rainwater to increase flood protection and reduce damage to waterways. The objective of this article is to investigate the integrity of residential rainwater harvesting systems, drawing on the results of the field inspection of 417 rainwater systems across Melbourne that was combined with a survey of householders' situation, maintenance behaviour and attitudes. Specifically, the study moves beyond the assumption that rainwater systems are always operational and functional and draws on the collected data to explore the various reasons and rates of failure associated with pumps and pump switches, leaving for later further exploration of the failure in other components such as the collection area, gutters, tank, and overflows. To the best of the authors' knowledge, there is no data like this in academic literature or in the water sector. Straightforward Bayesian Network models were constructed in order to analyse the factors contributing to various types of failures, including system age, type of use, the reason for installation, installer, and maintenance behaviour. Results show that a number of issues commonly exist, such as failure of pumps (5% of systems), automatic pump switches that mediate between the tank and reticulated water (9% of systems), and systems with inadequate setups (i.e. no pump) limiting their use. In conclusion, there appears to be a lack of enforcement or quality controls in both installation practices by sometimes unskilled contractors and lack of ongoing maintenance checks. Mechanisms for quality control and asset management are required, but difficult to promote or enforce. Further work is needed into how privately owned assets that have public benefits could be better managed.

Low-cost failure sensor design and development for water pipeline distribution systems.

PubMed

Khan, K; Widdop, P D; Day, A J; Wood, A S; Mounce, S R; Machell, J

2002-01-01

This paper describes the design and development of a new sensor which is low cost to manufacture and install and is reliable in operation with sufficient accuracy, resolution and repeatability for use in newly developed systems for pipeline monitoring and leakage detection. To provide an appropriate signal, the concept of a "failure" sensor is introduced, in which the output is not necessarily proportional to the input, but is unmistakably affected when an unusual event occurs. The design of this failure sensor is based on the water opacity which can be indicative of an unusual event in a water distribution network. The laboratory work and field trials necessary to design and prove out this type of failure sensor are described here. It is concluded that a low-cost failure sensor of this type has good potential for use in a comprehensive water monitoring and management system based on Artificial Neural Networks (ANN).

Environmental monitoring of selected pesticides and organic chemicals in urban stormwater recycling systems using passive sampling techniques.

PubMed

Page, Declan; Miotliński, Konrad; Gonzalez, Dennis; Barry, Karen; Dillon, Peter; Gallen, Christie

2014-03-01

Water recycling via aquifers has become a valuable tool to augment urban water supplies in many countries. This study reports the first use of passive samplers for monitoring of organic micropollutants in Managed Aquifer Recharge (MAR). Five different configurations of passive samplers were deployed in a stormwater treatment wetland, groundwater monitoring wells and a recovery tank to capture a range of polar and non-polar micropollutants present in the system. The passive samplers were analysed for a suite of pesticides, polycyclic aromatic hydrocarbons (PAHs) and other chemicals. As a result, 17 pesticides and pesticide degradation products, 5 PAHs and 8 other organic chemicals including flame retardants and fragrances were detected in urban stormwater recharging Aquifer Storage and Recovery (ASR) and an Aquifer Storage Transfer and Recovery (ASTR) system. Of the pesticides detected, diuron, metolachlor and chlorpyrifos were generally detected at the highest concentrations in one or more passive samplers, whereas chlorpyrifos, diuron, metolachlor, simazine, galaxolide and triallate were detected in multiple samplers. Fluorene was the PAH detected at the highest concentration and the flame retardant Tris(1-chloro-2-propyl)phosphate was the chemical detected in the greatest abundance at all sites. The passive samplers showed different efficiencies for capture of micropollutants with the Empore disc samplers giving the most reliable results. The results indicate generally low levels of organic micropollutants in the stormwater, as the contaminants detected were present at very low ng/L levels, generally two to four orders of magnitude below the drinking water guidelines (NHMRC, 2011). The efficiency of attenuation of these organic micropollutants during MAR was difficult to determine due to variations in the source water concentrations. Comparisons were made between different samplers, to give a field-based calibration where existing lab-based calibrations were

Environmental monitoring of selected pesticides and organic chemicals in urban stormwater recycling systems using passive sampling techniques

NASA Astrophysics Data System (ADS)

Page, Declan; Miotliński, Konrad; Gonzalez, Dennis; Barry, Karen; Dillon, Peter; Gallen, Christie

2014-03-01

Water recycling via aquifers has become a valuable tool to augment urban water supplies in many countries. This study reports the first use of passive samplers for monitoring of organic micropollutants in Managed Aquifer Recharge (MAR). Five different configurations of passive samplers were deployed in a stormwater treatment wetland, groundwater monitoring wells and a recovery tank to capture a range of polar and non-polar micropollutants present in the system. The passive samplers were analysed for a suite of pesticides, polycyclic aromatic hydrocarbons (PAHs) and other chemicals. As a result, 17 pesticides and pesticide degradation products, 5 PAHs and 8 other organic chemicals including flame retardants and fragrances were detected in urban stormwater recharging Aquifer Storage and Recovery (ASR) and an Aquifer Storage Transfer and Recovery (ASTR) system. Of the pesticides detected, diuron, metolachlor and chlorpyrifos were generally detected at the highest concentrations in one or more passive samplers, whereas chlorpyrifos, diuron, metolachlor, simazine, galaxolide and triallate were detected in multiple samplers. Fluorene was the PAH detected at the highest concentration and the flame retardant Tris(1-chloro-2-propyl)phosphate was the chemical detected in the greatest abundance at all sites. The passive samplers showed different efficiencies for capture of micropollutants with the Empore disc samplers giving the most reliable results. The results indicate generally low levels of organic micropollutants in the stormwater, as the contaminants detected were present at very low ng/L levels, generally two to four orders of magnitude below the drinking water guidelines (NHMRC, 2011). The efficiency of attenuation of these organic micropollutants during MAR was difficult to determine due to variations in the source water concentrations. Comparisons were made between different samplers, to give a field-based calibration where existing lab-based calibrations were

Processes in construction of failure management expert systems from device design information

NASA Technical Reports Server (NTRS)

Malin, Jane T.; Lance, Nick

1987-01-01

This paper analyzes the tasks and problem solving methods used by an engineer in constructing a failure management expert system from design information about the device to te diagnosed. An expert test engineer developed a trouble-shooting expert system based on device design information and experience with similar devices, rather than on specific expert knowledge gained from operating the device or troubleshooting its failures. The construction of the expert system was intensively observed and analyzed. This paper characterizes the knowledge, tasks, methods, and design decisions involved in constructing this type of expert system, and makes recommendations concerning tools for aiding and automating construction of such systems.

A Passive Wireless Multi-Sensor SAW Technology Device and System Perspectives

PubMed Central

Malocha, Donald C.; Gallagher, Mark; Fisher, Brian; Humphries, James; Gallagher, Daniel; Kozlovski, Nikolai

2013-01-01

This paper will discuss a SAW passive, wireless multi-sensor system under development by our group for the past several years. The device focus is on orthogonal frequency coded (OFC) SAW sensors, which use both frequency diversity and pulse position reflectors to encode the device ID and will be briefly contrasted to other embodiments. A synchronous correlator transceiver is used for the hardware and post processing and correlation techniques of the received signal to extract the sensor information will be presented. Critical device and system parameters addressed include encoding, operational range, SAW device parameters, post-processing, and antenna-SAW device integration. A fully developed 915 MHz OFC SAW multi-sensor system is used to show experimental results. The system is based on a software radio approach that provides great flexibility for future enhancements and diverse sensor applications. Several different sensor types using the OFC SAW platform are shown. PMID:23666124

Ascending and Descending in Virtual Reality: Simple and Safe System Using Passive Haptics.

PubMed

Nagao, Ryohei; Matsumoto, Keigo; Narumi, Takuji; Tanikawa, Tomohiro; Hirose, Michitaka

2018-04-01

This paper presents a novel interactive system that provides users with virtual reality (VR) experiences, wherein users feel as if they are ascending/descending stairs through passive haptic feedback. The passive haptic stimuli are provided by small bumps under the feet of users; these stimuli are provided to represent the edges of the stairs in the virtual environment. The visual stimuli of the stairs and shoes, provided by head-mounted displays, evoke a visuo-haptic interaction that modifies a user's perception of the floor shape. Our system enables users to experience all types of stairs, such as half-turn and spiral stairs, in a VR setting. We conducted a preliminary user study and two experiments to evaluate the proposed technique. The preliminary user study investigated the effectiveness of the basic idea associated with the proposed technique for the case of a user ascending stairs. The results demonstrated that the passive haptic feedback produced by the small bumps enhanced the user's feeling of presence and sense of ascending. We subsequently performed an experiment to investigate an improved viewpoint manipulation method and the interaction of the manipulation and haptics for both the ascending and descending cases. The experimental results demonstrated that the participants had a feeling of presence and felt a steep stair gradient under the condition of haptic feedback and viewpoint manipulation based on the characteristics of actual stair walking data. However, these results also indicated that the proposed system may not be as effective in providing a sense of descending stairs without an optimization of the haptic stimuli. We then redesigned the shape of the small bumps, and evaluated the design in a second experiment. The results indicated that the best shape to present haptic stimuli is a right triangle cross section in both the ascending and descending cases. Although it is necessary to install small protrusions in the determined direction, by

Mitigation of commutation failures in LCC-HVDC systems based on superconducting fault current limiters

NASA Astrophysics Data System (ADS)

Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook

2016-11-01

Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC-HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC-HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC-HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC-HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

Passive Magnetic Bearing

NASA Technical Reports Server (NTRS)

Studer, P. A.

1983-01-01

Magnetic bearing for limited rotation devices requires no feedback control system to sense and correct shaft position. Passive Magnetic Torsion Bearing requires no power supply and has no rubbing parts. Torsion wire restrains against axial instability. Magnetic flux geometry chosen to assure lateral stability with radial restoring force that maintains alignment.

Passive wall cooling panel with phase change material as a cooling agent

NASA Astrophysics Data System (ADS)

Majid, Masni A.; Tajudin, Rasyidah Ahmad; Salleh, Norhafizah; Hamid, Noor Azlina Abd

2017-11-01

The study was carried out to the determine performance of passive wall cooling panels by using Phase Change Materials as a cooling agent. This passive cooling system used cooling agent as natural energy storage without using any HVAC system. Eight full scale passive wall cooling panels were developed with the size 1500 mm (L) × 500 mm (W) × 100 mm (T). The cooling agent such as glycerine were filled in the tube with horizontal and vertical arrangement. The passive wall cooling panels were casting by using foamed concrete with density between 1200 kg/m3 - 1500 kg/m3. The passive wall cooling panels were tested in a small house and the differences of indoor and outdoor temperature was recorded. Passive wall cooling panels with glycerine as cooling agent in vertical arrangement showed the best performance with dropped of indoor air temperature within 3°C compared to outdoor air temperature. The lowest indoor air temperature recorded was 25°C from passive wall cooling panels with glycerine in vertical arrangement. From this study, the passive wall cooling system could be applied as it was environmental friendly and less maintenance.

Critical Infrastructure Vulnerability to Spatially Localized Failures with Applications to Chinese Railway System.

PubMed

Ouyang, Min; Tian, Hui; Wang, Zhenghua; Hong, Liu; Mao, Zijun

2017-01-17

This article studies a general type of initiating events in critical infrastructures, called spatially localized failures (SLFs), which are defined as the failure of a set of infrastructure components distributed in a spatially localized area due to damage sustained, while other components outside the area do not directly fail. These failures can be regarded as a special type of intentional attack, such as bomb or explosive assault, or a generalized modeling of the impact of localized natural hazards on large-scale systems. This article introduces three SLFs models: node centered SLFs, district-based SLFs, and circle-shaped SLFs, and proposes a SLFs-induced vulnerability analysis method from three aspects: identification of critical locations, comparisons of infrastructure vulnerability to random failures, topologically localized failures and SLFs, and quantification of infrastructure information value. The proposed SLFs-induced vulnerability analysis method is finally applied to the Chinese railway system and can be also easily adapted to analyze other critical infrastructures for valuable protection suggestions. © 2017 Society for Risk Analysis.

Modelling passive diastolic mechanics with quantitative MRI of cardiac structure and function.

PubMed

Wang, Vicky Y; Lam, H I; Ennis, Daniel B; Cowan, Brett R; Young, Alistair A; Nash, Martyn P

2009-10-01

The majority of patients with clinically diagnosed heart failure have normal systolic pump function and are commonly categorized as suffering from diastolic heart failure. The left ventricle (LV) remodels its structure and function to adapt to pathophysiological changes in geometry and loading conditions, which in turn can alter the passive ventricular mechanics. In order to better understand passive ventricular mechanics, a LV finite element (FE) model was customized to geometric data segmented from in vivo tagged magnetic resonance images (MRI) data and myofibre orientation derived from ex vivo diffusion tensor MRI (DTMRI) of a canine heart using nonlinear finite element fitting techniques. MRI tissue tagging enables quantitative evaluation of cardiac mechanical function with high spatial and temporal resolution, whilst the direction of maximum water diffusion in each voxel of a DTMRI directly corresponds to the local myocardial fibre orientation. Due to differences in myocardial geometry between in vivo and ex vivo imaging, myofibre orientations were mapped into the geometric FE model using host mesh fitting (a free form deformation technique). Pressure recordings, temporally synchronized to the tagging data, were used as the loading constraints to simulate the LV deformation during diastole. Simulation of diastolic LV mechanics allowed us to estimate the stiffness of the passive LV myocardium based on kinematic data obtained from tagged MRI. Integrated physiological modelling of this kind will allow more insight into mechanics of the LV on an individualized basis, thereby improving our understanding of the underlying structural basis of mechanical dysfunction under pathological conditions.

Correlation between serum total globulins and gamma globulins and their use to diagnose failure of passive transfer in foals.

PubMed

Fouché, Nathalie; Graubner, Claudia; Howard, Judith

2014-11-01

Various assays have been used as an aid to diagnose failure of passive transfer (FPT) of immunoglobulins in neonatal foals, but often lack sensitivity as screening tests, or are time consuming to perform and impractical as confirmatory tests. The aim of the present study was to evaluate whether measurement of serum total globulins (TG; i.e. total protein minus albumin) can be used to estimate the electrophoretic gamma globulin (EGG) fraction in hospitalised neonatal foals with suspected FPT. Sample data from 56 foals were evaluated retrospectively. The coefficient of rank correlation was 0.84. The area under the curve of ROC analysis was 0.887, 0.922 and 0.930 for EGG concentrations <2 g/L, < 4 g/L and <8 g/L, respectively. Cut-offs for TG achieved ≥90% sensitivity for detecting EGG <2 g/L, < 4 g/L and <8 g/L, with negative predictive values of >97% and >94%, using prevalence of 15% and 30%, respectively. These results suggest that measurement of TG can be used as a guide to predicting EGG, provided that appropriate cut-off values are selected, and this technique could be a useful initial screening test for FPT in foals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Columbia County Habitat for Humanity Passive Townhomes

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

Dentz, Jordan; Alaigh, Kunal; Dadia, Devanshi

2016-03-18

Columbia County (New York) Habitat for Humanity built a pair of townhomes to Passive House criteria with the purpose of exploring approaches for achieving Passive House performance and to eventually develop a prototype design for future projects. The project utilized a 2x6 frame wall with a structural insulated panel curtain wall and a ventilated attic over a sealed OSB ceiling air barrier. Mechanical systems include a single head, wall mounted ductless mini-split heat pump in each unit and a heat recovery ventilator. Costs were $26,000 per unit higher for Passive House construction compared with the same home built to ENERGYmore » STAR version 3 specifications, representing about 18% of total construction cost. This report discusses the cost components, energy modeling results and lessons from construction. Two alternative ventilation systems are analyzed: a central system; and, a point-source system with small through-wall units distributed throughout the house. The report includes a design and cost analysis of these two approaches.« less

Study on real-time elevator brake failure predictive system

NASA Astrophysics Data System (ADS)

Guo, Jun; Fan, Jinwei

2013-10-01

This paper presented a real-time failure predictive system of the elevator brake. Through inspecting the running state of the coil by a high precision long range laser triangulation non-contact measurement sensor, the displacement curve of the coil is gathered without interfering the original system. By analyzing the displacement data using the diagnostic algorithm, the hidden danger of the brake system can be discovered in time and thus avoid the according accident.

ISS Expedition 18 Fluids and Combustion Facility (FCF) Combustion Integration Rack (CIR) Passive Rack Isolation System (

NASA Image and Video Library

2009-01-05

ISS018-E-017796 (5 Jan. 2009) --- Astronaut Sandra Magnus, Expedition 18 flight engineer, works on the Fluids and Combustion Facility (FCF) Combustion Integration Rack (CIR) Passive Rack Isolation System (PaRIS) in the Destiny laboratory of the International Space Station.

Parameters influencing the course of passive drug loading into lipid nanoemulsions.

PubMed

Göke, Katrin; Bunjes, Heike

2018-05-01

Passive drug loading can be used to effectively identify suitable colloidal lipid carrier systems for poorly water-soluble drugs. This method comprises incubation of preformed carrier systems with drug powder and subsequent determination of the resulting drug load of the carrier particles. Until now, the passive loading mechanism is unknown, which complicates reliable routine use. In this work, the influence of drug characteristics on the course of passive loading was investigated systematically varying drug surface area and drug solubility. Fenofibrate and flufenamic acid were used as model drugs; the carrier system was a trimyristin nanodispersion. Loading progress was analyzed by UV spectroscopy or by a novel method based on differential scanning calorimetry. While increasing drug solubility by micelle incorporation did not speed up passive loading, a large drug surface area and high water solubility were key parameters for fast loading. Since both factors are crucial in drug dissolution as described by the Noyes-Whitney equation, these findings point to a dissolution-diffusion-based passive loading mechanism. Accordingly, passive loading also occurred when drug and carrier particles were separated by a dialysis membrane. Knowledge of the loading mechanism allows optimizing the conditions for future passive loading studies and assessing the limitations of the method. Copyright © 2017 Elsevier B.V. All rights reserved.

Passive immunisation, an old idea revisited: Basic principles and application to modern animal production systems.

PubMed

Hedegaard, Chris J; Heegaard, Peter M H

2016-06-01

Immunisation by administration of antibodies (immunoglobulins) has been known for more than one hundred years as a very efficient means of obtaining immediate, short-lived protection against infection and/or against the disease-causing effects of toxins from microbial pathogens and from other sources. Thus, due to its rapid action, passive immunisation is often used to treat disease caused by infection and/or toxin exposure. However immunoglobulins may also be administered prior to exposure to infection and/or toxin, although they will not provide long-lasting protection as is seen with active immunisation (vaccination) in which an immunological memory is established by controlled exposure of the host to the pathogen in question. With multi-factorial infectious diseases in production animals, especially those that have proven hard to control by vaccination, the potential of passive immunisation remains big. This review highlights a number of examples on the use of passive immunisation for the control of infectious disease in the modern production of a range of animals, including pigs, cattle, sheep, goat, poultry and fish. Special emphasis is given on the enablement of passive immunisation strategies in these production systems through low cost and ease of use as well as on the sources, composition and purity of immunoglobulin preparations used and their benefits as compared to current measures, including vaccination (also comprising maternal vaccination), antibiotics and feed additives such as spray-dried plasma. It is concluded that provided highly efficient, relatively low-price immunoglobulin products are available, passive immunisation has a clear role in the modern animal production sector as a means of controlling infectious diseases, importantly with a very low risk of causing development of bacterial resistance, thus constituting a real and widely applicable alternative to antibiotics. Copyright © 2016 Elsevier B.V. All rights reserved.

Collaborative Group Learning and Knowledge Building to Address Information Systems Project Failure

ERIC Educational Resources Information Center

Angelo, Raymond

2011-01-01

Approximately half of the information systems (IS) projects implemented each year are considered failures. These failed projects cost billions of dollars annually. Failures can be due to projects being delivered late, over-budget, abandoned after significant time and resource investment, or failing to achieve desired results. More often than not,…

A Passive Magnetic Bearing Flywheel

NASA Technical Reports Server (NTRS)

Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

2002-01-01

A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

Passive isolation/damping system for the Hubble space telescope reaction wheels

NASA Technical Reports Server (NTRS)

Hasha, Martin D.

1987-01-01

NASA's Hubble Space Telescope contain large, diffraction limited optics with extraordinary resolution and performance for surpassing existing observatories. The need to reduce structural borne vibration and resultant optical jitter from critical Pointing Control System components, Reaction Wheels, prompted the feasibility investigation and eventual development of a passive isolation system. Alternative design concepts considered were required to meet a host of stringent specifications and pass rigid tests to be successfully verified and integrated into the already built flight vehicle. The final design employs multiple arrays of fluid damped springs that attenuate over a wide spectrum, while confining newly introduced resonances to benign regions of vehicle dynamic response. Overall jitter improvement of roughly a factor of 2 to 3 is attained with this system. The basis, evolution, and performance of the isolation system, specifically discussing design concepts considered, optimization studies, development lessons learned, innovative features, and analytical and ground test verified results are presented.

Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine

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

Prikhodko, Vitaly Y; Parks, II, James E; Pihl, Josh A

Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three-way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in the oxygen-rich exhaust. Thus, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH3 production via a passive SCR approach is of interest.more » In a passive SCR system, NH3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. 15% excess NH3 production over a 1:1 NH3:NOX ratio was required (via longer rich cycle timing) to achieve 99.7% NOX conversion at an SCR average inlet temperature of 350 C. Increasing NH3 generation further resulted in even higher NOX conversion; however, tailpipe NH3 emissions resulted. At higher temperatures, NH3 oxidation becomes important and limits NH3 availability for NOX reduction. At the engine conditions studied here, greater than 99% NOX conversion was achieved with passive SCR while delivering

Development of a passive sampler for gaseous mercury

NASA Astrophysics Data System (ADS)

Gustin, M. S.; Lyman, S. N.; Kilner, P.; Prestbo, E.

2011-10-01

Here we describe work toward development of the components of a cost effective passive sampling system for gaseous Hg that could be broadly deployed by nontechnical staff. The passive sampling system included an external shield to reduce turbulence and exposure to precipitation and dust, a diffusive housing that directly protects the collection surface during deployment and handling, and a collection surface. A protocol for cleaning and deploying the sampler and an analytical method were developed. Our final design consisted of a polycarbonate external shield enclosing a custom diffusive housing made from expanded PTFE tubing. Two collection surfaces were investigated, gold sputter-coated quartz plates and silver wires. Research showed the former would require extensive quality control for use, while the latter had interferences with other atmosphere constituents. Although the gold surface exhibited the best performance over space and time, gradual passivation would limit reuse. For both surfaces lack of contamination during shipping, deployment and storage indicated that the handling protocols developed worked well with nontechnical staff. We suggest that the basis for this passive sampling system is sound, but further exploration and development of a reliable collection surface is needed.

Emerging Needs for Pervasive Passive Wireless Sensor Networks on Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Wilson, William C.; Juarez, Peter D.

2014-01-01

NASA is investigating passive wireless sensor technology to reduce instrumentation mass and volume in ground testing, air flight, and space exploration applications. Vehicle health monitoring systems (VHMS) are desired on all aerospace programs to ensure the safety of the crew and the vehicles. Pervasive passive wireless sensor networks facilitate VHMS on aerospace vehicles. Future wireless sensor networks on board aerospace vehicles will be heterogeneous and will require active and passive network systems. Since much has been published on active wireless sensor networks, this work will focus on the need for passive wireless sensor networks on aerospace vehicles. Several passive wireless technologies such as microelectromechanical systems MEMS, SAW, backscatter, and chipless RFID techniques, have all shown potential to meet the pervasive sensing needs for aerospace VHMS applications. A SAW VHMS application will be presented. In addition, application areas including ground testing, hypersonic aircraft and spacecraft will be explored along with some of the harsh environments found in aerospace applications.

Practical, redundant, failure-tolerant, self-reconfiguring embedded system architecture

DOEpatents

Klarer, Paul R.; Hayward, David R.; Amai, Wendy A.

2006-10-03

This invention relates to system architectures, specifically failure-tolerant and self-reconfiguring embedded system architectures. The invention provides both a method and architecture for redundancy. There can be redundancy in both software and hardware for multiple levels of redundancy. The invention provides a self-reconfiguring architecture for activating redundant modules whenever other modules fail. The architecture comprises: a communication backbone connected to two or more processors and software modules running on each of the processors. Each software module runs on one processor and resides on one or more of the other processors to be available as a backup module in the event of failure. Each module and backup module reports its status over the communication backbone. If a primary module does not report, its backup module takes over its function. If the primary module becomes available again, the backup module returns to its backup status.

Liver failure induces a systemic inflammatory response. Prevention by recombinant N-terminal bactericidal/permeability-increasing protein.

PubMed Central

Boermeester, M. A.; Houdijk, A. P.; Meyer, S.; Cuesta, M. A.; Appelmelk, B. J.; Wesdorp, R. I.; Hack, C. E.; Van Leeuwen, P. A.

1995-01-01

The observed increased susceptibility of patients with fulminant hepatic failure for local and systemic infections has been hypothesized to be due to a failure for the hepatic clearance function and subsequent leaking of endogenous endotoxins into the systemic circulation. However, experimental evidence for such a systemic inflammation during liver failure due to endogenous endotoxemia is lacking. Therefore, we designed a study to clarify whether circulating endotoxins due to liver failure could lead to the development of systemic inflammations. In a rat model for liver failure induced by a two-thirds partial hepatectomy, we evaluated the course of circulating tumor necrosis factor and interleukin-6, changes in blood chemistry and hemodynamics, and histopathological changes in the lungs. Partially hepatectomized animals, but not sham-operated animals, demonstrated cardiac failure, increased levels of creatinin and urea, metabolic acidosis, high plasma levels of tumor necrosis factor and interleukin-6, and an influx of PMNs in the lungs-together indicating the development of a systemic inflammatory response. Continuous infusion of recombinant N-terminal bactericidal/permeability-increasing protein (rBPI23), a well described endotoxin-neutralizing protein, prevented these inflammatory reactions. Ex vivo experiments with rat plasma samples confirmed the presence of circulating endotoxins in partially hepatectomized rats as opposed to those treated with rBPI23. Thus, our results indicate that the early phase of liver failure induces a systemic inflammatory response triggered by circulating endotoxins, which can be prevented by perioperative infusion of rBPI23. Images Figure 2 PMID:7485405

Passive magnetic bearing element with minimal power losses

DOEpatents

Post, R.F.

1998-12-08

Systems employing passive magnetic bearing elements having minimal power losses are provided. Improved stabilizing elements are shown, employing periodic magnet arrays and inductively loaded circuits, but with improved characteristics compared to the elements disclosed in US Patent No. 5,495,221 entitled ``Dynamically Stable Magnetic Suspension/Bearing System.`` The improvements relate to increasing the magnitude of the force derivative, while at the same time reducing the power dissipated during the normal operation of the bearing system, to provide a passive bearing system that has virtually no losses under equilibrium conditions, that is, when the supported system is not subject to any accelerations except those of gravity. 8 figs.

Passive magnetic bearing element with minimal power losses

DOEpatents

Post, Richard F.

1998-01-01

Systems employing passive magnetic bearing elements having minimal power losses are provided. Improved stabilizing elements are shown, employing periodic magnet arrays and inductively loaded circuits, but with improved characteristics compared to the elements disclosed in U.S. Patent No. 5,495,221 entitled "Dynamically Stable Magnetic Suspension/Bearing System." The improvements relate to increasing the magnitude of the force derivative, while at the same time reducing the power dissipated during the normal operation of the bearing system, to provide a passive bearing system that has virtually no losses under equilibrium conditions, that is, when the supported system is not subject to any accelerations except those of gravity.

Development of Passive Fuel Cell Thermal Management Heat Exchanger

NASA Technical Reports Server (NTRS)

Burke, Kenneth A.; Jakupca, Ian J.; Colozza, Anthony J.

2010-01-01

The NASA Glenn Research Center is developing advanced passive thermal management technology to reduce the mass and improve the reliability of space fuel cell systems for the NASA Exploration program. The passive thermal management system relies on heat conduction within highly thermally conductive cooling plates to move the heat from the central portion of the cell stack out to the edges of the fuel cell stack. Using the passive approach eliminates the need for a coolant pump and other cooling loop components within the fuel cell system which reduces mass and improves overall system reliability. Previous development demonstrated the performance of suitable highly thermally conductive cooling plates that could conduct the heat, provide a sufficiently uniform temperature heat sink for each cell of the fuel cell stack, and be substantially lighter than the conventional thermal management approach. Tests were run with different materials to evaluate the design approach to a heat exchanger that could interface with the edges of the passive cooling plates. Measurements were made during fuel cell operation to determine the temperature of individual cooling plates and also to determine the temperature uniformity from one cooling plate to another.

Passive designs and renewable energy systems optimization of a net zero energy building in Embrun/France

NASA Astrophysics Data System (ADS)

Harkouss, F.; Biwole, P. H.; Fardoun, F.

2018-05-01

Buildings’ optimization is a smart method to inspect the available design choices starting from passive strategies, to energy efficient systems and finally towards the adequate renewable energy system to be implemented. This paper outlines the methodology and the cost-effectiveness potential for optimizing the design of net-zero energy building in a French city; Embrun. The non-dominated sorting genetic algorithm is chosen in order to minimize thermal, electrical demands and life cycle cost while reaching the net zero energy balance; and thus getting the Pareto-front. Elimination and Choice Expressing the Reality decision making method is applied to the Pareto-front so as to obtain one optimal solution. A wide range of energy efficiency measures are investigated, besides solar energy systems are employed to produce required electricity and hot water for domestic purposes. The results indicate that the appropriate selection of the passive parameters is very important and critical in reducing the building energy consumption. The optimum design parameters yield to a decrease of building’s thermal loads and life cycle cost by 32.96% and 14.47% respectively.

Passive bistatic radar analysis

NASA Astrophysics Data System (ADS)

O'Hagan, Daniel W.; Kuschel, H.; Schiller, Joachim

2009-06-01

Passive Bistatic Radar (PBR) research is at its zenith with several notable PBR systems currently operational, or available for deployment. Such PBRs include the Manastash Ridge Radar (MRR) developed for and by academia; Silent Sentry developed as a commercial concern by Lockheed Martin; and Homeland Alerter (HA100) also a commercial system developed by Thales. However at present, despite the existence of numerous PBR prototypes, take up of commercial passive radar technology remains slow. This is due in part to technology immaturity, in part to politics, and particularly due to the fact that monostatic radars perform so well. If PBRs are to enjoy longevity as a viable technology then it is imperative that they address certain niche application areas, with the aforementioned MRR being one prime example of this. The focus of this paper will be an analysis of a PBR system that utilised FM radio signals of opportunity to detect aircraft targets with an RCS generally not lower than 20 m2. The paper will demonstrate the theoretical detection coverage of an FM based PBR operating in a severe interference environment.

Sensor failure and multivariable control for airbreathing propulsion systems. Ph.D. Thesis - Dec. 1979 Final Report

NASA Technical Reports Server (NTRS)

Behbehani, K.

1980-01-01

A new sensor/actuator failure analysis technique for turbofan jet engines was developed. Three phases of failure analysis, namely detection, isolation, and accommodation are considered. Failure detection and isolation techniques are developed by utilizing the concept of Generalized Likelihood Ratio (GLR) tests. These techniques are applicable to both time varying and time invariant systems. Three GLR detectors are developed for: (1) hard-over sensor failure; (2) hard-over actuator failure; and (3) brief disturbances in the actuators. The probability distribution of the GLR detectors and the detectability of sensor/actuator failures are established. Failure type is determined by the maximum of the GLR detectors. Failure accommodation is accomplished by extending the Multivariable Nyquest Array (MNA) control design techniques to nonsquare system designs. The performance and effectiveness of the failure analysis technique are studied by applying the technique to a turbofan jet engine, namely the Quiet Clean Short Haul Experimental Engine (QCSEE). Single and multiple sensor/actuator failures in the QCSEE are simulated and analyzed and the effects of model degradation are studied.

Technical - Economic Research for Passive Buildings

NASA Astrophysics Data System (ADS)

Miniotaite, Ruta

2017-10-01

A newly constructed passive house must save 80 % of heat resources; otherwise it is not a passive house. The heating energy demand of a passive building is less than 15 kWh/m2 per year. However, a passive house is something more than just an energy-saving house. This concept involves sustainable, high-quality, valuable, healthy and durable construction. Features of a passive house: high insulation of envelope components, high-quality windows, good tightness of the building, regenerative ventilation system and elimination of thermal bridges. The Energy Performance of Buildings Directive (EPBD) 61 requires all new public buildings to become near-zero energy buildings by 2019 and will be extended to all new buildings by 2021. This concept involves sustainable, high-quality, valuable, healthy and durable construction. Foundation, walls and roofs are the most essential elements of a house. The type of foundation for a private house is selected considering many factors. The article examines technological and structural solutions for passive buildings foundation, walls and roofs. The technical-economic comparison of the main structures of a passive house revealed that it is cheaper to install an adequately designed concrete slab foundation than to build strip or pile foundation and the floor separately. Timber stud walls are the cheapest wall option for a passive house and 45-51% cheaper compared to other options. The comparison of roofs and ceilings showed that insulation of the ceiling is 25% more efficient than insulation of the roof. The comparison of the main envelope elements efficiency by multiple-criteria evaluation methods showed that it is economically feasible to install concrete slab on ground foundation, stud walls with sheet cladding and a pitched roof with insulated ceiling.

Orion Passive Thermal: Control Overview

NASA Technical Reports Server (NTRS)

Alvarez-Hermandez, Angel; Miller, Stephen W.

2009-01-01

A general overview of the NASA Orion Passive Thermal Control System (PTCS) is presented. The topics include: 1) Orion in CxP Hierarchy; 2) General Orion Description/Orientation; and 3) Orion PTCS Overview.

High spatial resolution passive microwave sounding systems

NASA Technical Reports Server (NTRS)

Staelin, D. H.; Rosenkranz, P. W.; Bonanni, P. G.; Gasiewski, A. W.

1986-01-01

Two extensive series of flights aboard the ER-2 aircraft were conducted with the MIT 118 GHz imaging spectrometer together with a 53.6 GHz nadir channel and a TV camera record of the mission. Other microwave sensors, including a 183 GHz imaging spectrometer were flown simultaneously by other research groups. Work also continued on evaluating the impact of high-resolution passive microwave soundings upon numerical weather prediction models.

Immunity-based detection, identification, and evaluation of aircraft sub-system failures

NASA Astrophysics Data System (ADS)

Moncayo, Hever Y.

This thesis describes the design, development, and flight-simulation testing of an integrated Artificial Immune System (AIS) for detection, identification, and evaluation of a wide variety of sensor, actuator, propulsion, and structural failures/damages including the prediction of the achievable states and other limitations on performance and handling qualities. The AIS scheme achieves high detection rate and low number of false alarms for all the failure categories considered. Data collected using a motion-based flight simulator are used to define the self for an extended sub-region of the flight envelope. The NASA IFCS F-15 research aircraft model is used and represents a supersonic fighter which include model following adaptive control laws based on non-linear dynamic inversion and artificial neural network augmentation. The flight simulation tests are designed to analyze and demonstrate the performance of the immunity-based aircraft failure detection, identification and evaluation (FDIE) scheme. A general robustness analysis is also presented by determining the achievable limits for a desired performance in the presence of atmospheric perturbations. For the purpose of this work, the integrated AIS scheme is implemented based on three main components. The first component performs the detection when one of the considered failures is present in the system. The second component consists in the identification of the failure category and the classification according to the failed element. During the third phase a general evaluation of the failure is performed with the estimation of the magnitude/severity of the failure and the prediction of its effect on reducing the flight envelope of the aircraft system. Solutions and alternatives to specific design issues of the AIS scheme, such as data clustering and empty space optimization, data fusion and duplication removal, definition of features, dimensionality reduction, and selection of cluster/detector shape are also

LDEF electronic systems: Successes, failures, and lessons

NASA Technical Reports Server (NTRS)

Miller, Emmett; Porter, Dave; Smith, Dave; Brooks, Larry; Levorsen, Joe; Mulkey, Owen

1991-01-01

Following the Long Duration Exposure Facility (LDEF) retrieval, the Systems Special Investigation Group (SIG) participated in an extensive series of tests of various electronic systems, including the NASA provided data and initiate systems, and some experiment systems. Overall, these were found to have performed remarkably well, even though most were designed and tested under limited budgets and used at least some nonspace qualified components. However, several anomalies were observed, including a few which resulted in some loss of data. The postflight test program objectives, observations, and lessons learned from these examinations are discussed. All analyses are not yet complete, but observations to date will be summarized, including the Boeing experiment component studies and failure analysis results related to the Interstellar Gas Experiment. Based upon these observations, suggestions for avoiding similar problems on future programs are presented.

Availability and mean time between failures of redundant systems with random maintenance of subsystems

NASA Technical Reports Server (NTRS)

Schneeweiss, W.

1977-01-01

It is shown how the availability and MTBF (Mean Time Between Failures) of a redundant system with subsystems maintenanced at the points of so-called stationary renewal processes can be determined from the distributions of the intervals between maintenance actions and of the failure-free operating intervals of the subsystems. The results make it possible, for example, to determine the frequency and duration of hidden failure states in computers which are incidentally corrected during the repair of observed failures.

Second Law based definition of passivity/activity of devices

NASA Astrophysics Data System (ADS)

Sundqvist, Kyle M.; Ferry, David K.; Kish, Laszlo B.

2017-10-01

Recently, our efforts to clarify the old question, if a memristor is a passive or active device [1], triggered debates between engineers, who have had advanced definitions of passivity/activity of devices, and physicists with significantly different views about this seemingly simple question. This debate triggered our efforts to test the well-known engineering concepts about passivity/activity in a deeper way, challenging them by statistical physics. It is shown that the advanced engineering definition of passivity/activity of devices is self-contradictory when a thermodynamical system executing Johnson-Nyquist noise is present. A new, statistical physical, self-consistent definition based on the Second Law of Thermodynamics is introduced. It is also shown that, in a system with uniform temperature distribution, any rectifier circuitry that can rectify thermal noise must contain an active circuit element, according to both the engineering and statistical physical definitions.

Passive wireless antenna sensors for crack detection and shear/compression sensing

NASA Astrophysics Data System (ADS)

Mohammad, Irshad

Despite the fact that engineering components and structures are carefully designed against fatigue failures, 50 to 90% of mechanical failures are due to fatigue crack development. The severity of the failure depends on both the crack length and its orientation. Many types of sensors are available that can detect fatigue crack propagation. However, crack orientation detection has been rarely reported in the literature. We evaluated a patch antenna sensor capable of detecting crack propagation as well as crack orientation changes. The aim of these sensors would be to evaluate the real-time health condition of metallic structures to avoid catastrophic failures. The proposed crack sensing system consists of a dielectric substrate with a ground plane on one side of the substrate and an antenna patch printed on the other side of the substrate. The ground plane and the antenna patch, both conductive in nature, form an electromagnetic resonant cavity that radiates at distinct frequencies. These frequencies are monitored to evaluate the condition of cracks. A wireless sensor array can be realized by implementing a wireless interrogation unit. The scientific merits of this research are: 1) high sensitivity: it was demonstrated that the antenna sensors can detect crack growth with a sub-millimeter resolution; 2) passive wireless operation: based on microstrip antennas, the antenna sensors encode the sensing information in the backscattered antenna signal and thus can transmit the information without needing a local battery; 3) thin and conformal: the entire sensor unit is less than a millimeter thick and highly conformal; 4) crack orientation detection: the crack orientation on the structure can be precisely evaluated based on a single parameter, which only few sensors can accomplish. In addition to crack detection, the patch antenna sensors are also investigated for measuring shear and pressure forces, with an aim to study the formation, diagnostics and prevention of foot

Electronic systems failures and anomalies attributed to electromagnetic interference

NASA Technical Reports Server (NTRS)

Leach, R. D. (Editor); Alexander, M. B. (Editor)

1995-01-01

The effects of electromagnetic interference can be very detrimental to electronic systems utilized in space missions. Assuring that subsystems and systems are electrically compatible is an important engineering function necessary to assure mission success. This reference publication will acquaint the reader with spacecraft electronic systems failures and anomalies caused by electromagnetic interference and will show the importance of electromagnetic compatibility activities in conjunction with space flight programs. It is also hoped that the report will illustrate that evolving electronic systems are increasingly sensitive to electromagnetic interference and that NASA personnel must continue to diligently pursue electromagnetic compatibility on space flight systems.

Common Cause Failures and Ultra Reliability

NASA Technical Reports Server (NTRS)

Jones, Harry W.

2012-01-01

A common cause failure occurs when several failures have the same origin. Common cause failures are either common event failures, where the cause is a single external event, or common mode failures, where two systems fail in the same way for the same reason. Common mode failures can occur at different times because of a design defect or a repeated external event. Common event failures reduce the reliability of on-line redundant systems but not of systems using off-line spare parts. Common mode failures reduce the dependability of systems using off-line spare parts and on-line redundancy.

Pressure oscillations occurring in a centrifugal compressor system with and without passive and active surge control

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

Jungowski, W.M.; Weiss, M.H.; Price, G.R.

1996-01-01

A study of pressure oscillations occurring in small centrifugal compressor systems without a plenum is presented. Active and passive surge control were investigated theoretically and experimentally for systems with various inlet and discharge piping configurations. The determination of static and dynamic stability criteria was based on Greitzer`s (1981) lumped parameter model modified to accommodate capacitance of the piping. Experimentally, passive control using globe valves closely coupled to the compressor prevented the occurrence of surge even with the flow reduced to zero. Active control with a sleeve valve located at the compressor was effective but involved a significant component of passivemore » throttling which reduced the compressor efficiency. With an oscillator connected to a short side branch at the compressor, effective active control was achieved without throttling. Both methods of active control reduced the flow rate at surge onset by about 30%. In general, the experiments qualitatively confirmed the derived stability criteria.« less

Stochastic Availability of a Repairable System with an Age - and Maintenance - Dependent Failure Rate,

DTIC Science & Technology

1982-06-01

STOCKATZC LV AaMIQ.YN 0gp M@lIm iii s m -r ANAs WgLMSZIb 940=04 WoeU-O PolytechnicInstitute June 1982 Stochastic Availability of a Repairable System ...STOCHASTIC AVAILABILITY OF A REPAIRABLE SYSTEM WITH AN AGE AND MAINTENANCE DEPENDENT FAILURE RATE by JACK-KANG CHAN June 1982 Report No..Poly EE/CS 82-004...1.1 Concepts of System Availability 1 1.2 Maintenance and Failure Rate 7 1.3 Summary Chapter 2 SYSTEM4 MODEL 2.1 A Repairable System with Lintenance

Micro and nano devices in passive millimetre wave imaging systems

NASA Astrophysics Data System (ADS)

Appleby, R.

2013-06-01

The impact of micro and nano technology on millimetre wave imaging from the post war years to the present day is reviewed. In the 1950s whisker contacted diodes in mixers and vacuum tubes were used to realise both radiometers and radars but required considerable skill to realise the performance needed. Development of planar semiconductor devices such as Gunn and Schottky diodes revolutionised mixer performance and provided considerable improvement. The next major breakthrough was high frequency transistors based on gallium arsenide which were initially used at intermediate frequencies but later after further development at millimeter wave frequencies. More recently Monolithic Microwave Integrated circuits(MMICs) offer exceptional performance and the opportunity for innovative design in passive imaging systems. In the future the use of micro and nano technology will continue to drive system performance and we can expect to see integration of antennae, millimetre wave and sub millimetre wave circuits and signal processing.

Equivalent Air Spring Suspension Model for Quarter-Passive Model of Passenger Vehicles

PubMed Central

Abid, Haider J.; Chen, Jie; Nassar, Ameen A.

2015-01-01

This paper investigates the GENSIS air spring suspension system equivalence to a passive suspension system. The SIMULINK simulation together with the OptiY optimization is used to obtain the air spring suspension model equivalent to passive suspension system, where the car body response difference from both systems with the same road profile inputs is used as the objective function for optimization (OptiY program). The parameters of air spring system such as initial pressure, volume of bag, length of surge pipe, diameter of surge pipe, and volume of reservoir are obtained from optimization. The simulation results show that the air spring suspension equivalent system can produce responses very close to the passive suspension system. PMID:27351020

Equivalent Air Spring Suspension Model for Quarter-Passive Model of Passenger Vehicles.

PubMed

Abid, Haider J; Chen, Jie; Nassar, Ameen A

2015-01-01

This paper investigates the GENSIS air spring suspension system equivalence to a passive suspension system. The SIMULINK simulation together with the OptiY optimization is used to obtain the air spring suspension model equivalent to passive suspension system, where the car body response difference from both systems with the same road profile inputs is used as the objective function for optimization (OptiY program). The parameters of air spring system such as initial pressure, volume of bag, length of surge pipe, diameter of surge pipe, and volume of reservoir are obtained from optimization. The simulation results show that the air spring suspension equivalent system can produce responses very close to the passive suspension system.

Fast correlation method for passive-solar design

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

Wray, W.O.; Biehl, F.A.; Kosiewicz, C.E.

1982-01-01

A passive-solar design manual for single-family detached residences and dormitory-type buildings is being developed. The design procedure employed in the manual is a simplification of the original monthly solar load ratio (SLR) method. The new SLR correlations involve a single constant for each system. The correlation constant appears as a scale factor permitting the use of a universal performance curve for all passive systems. Furthermore, by providing location-dependent correlations between the annual solar heating fraction (SHF) and the minimum monthly SHF, we have eliminated the need to perform an SLR calculation for each month of the heating season.

A CTE matched hard solder passively cooled laser diode package combined with nXLT facet passivation enables high power, high reliability operation

NASA Astrophysics Data System (ADS)

Hodges, Aaron; Wang, Jun; DeFranza, Mark; Liu, Xingsheng; Vivian, Bill; Johnson, Curt; Crump, Paul; Leisher, Paul; DeVito, Mark; Martinsen, Robert; Bell, Jacob

2007-04-01

A conductively cooled laser diode package design with hard AuSn solder and CTE matched sub mount is presented. We discuss how this platform eliminates the failure mechanisms associated with indium solder. We present the problem of catastrophic optical mirror damage (COMD) and show that nLight's nXLT TM facet passivation technology effectively eliminates facet defect initiated COMD as a failure mechanism for both single emitter and bar format laser diodes. By combining these technologies we have developed a product that has high reliability at high powers, even at increased operation temperatures. We present early results from on-going accelerated life testing of this configuration that suggests an 808nm, 30% fill factor device will have a MTTF of more than 21khrs at 60W CW, 25°C operating conditions and a MTTF of more than 6.4khrs when operated under hard pulsed (1 second on, 1 second off) conditions.

Hybrid Active-Passive Systems for Control of Aircraft Interior Noise

NASA Technical Reports Server (NTRS)

Fuller, Chris R.; Palumbo, Dan (Technical Monitor)

2002-01-01

It was proposed to continue with development and application in the two active-passive areas of Active Tuned Vibration Absorbers (ATVA) and smart foam applied to the reduction of interior noise in aircraft. In general the work was focused on making both techniques more efficient, practical and robust thus increasing their application potential. The work was also concerned with demonstrating the potential of these two technologies under realistic implementations as well as understanding the fundamental physics of the systems. The proposed work consisted of a three-year program and was tightly coordinated with related work being carried out in the Structural Acoustics Branch at NASA LaRC. The work was supervised and coordinated through all phases by Prof Chris Fuller of Va Tech.

Interlanguage Passive Construction

ERIC Educational Resources Information Center

Simargool, Nirada

2008-01-01

Because the appearance of the passive construction varies cross linguistically, differences exist in the interlanguage (IL) passives attempted by learners of English. One such difference is the widely studied IL pseudo passive, as in "*new cars must keep inside" produced by Chinese speakers. The belief that this is a reflection of L1 language…

A lab-based study of subground passive cooling system for indoor temperature control

NASA Astrophysics Data System (ADS)

Chok, Mun-Hong; Chan, Chee-Ming

2017-11-01

Passive cooling is an alternative cooling technique which helps to reduce high energy consumption. Respectively, dredged marine soil (DMS) is either being dumped or disposed as waste materials. Dredging works had resulted high labor cost, therefore reuse DMS as to fill it along the coastal area. In this study, DMS chosen to examine the effectiveness of passive cooling system by model tests. Soil characterization were carried out according to BS1377: Part 2: 1990. Model were made into scale of 3 cm to 1 m. Heat exchange unit consists of three pipe designs namely, parallel, ramp and spiral. Preliminary tests including flow rate test and soil sample selection were done to select the best heat exchange unit to carry out the model test. Model test is classified into 2 conditions, day and night, each condition consists of 4 configurations which the temperature results are determined. The result shows that window left open and fan switched on (WO/FO) recorded the most effective cooling effects, from 29 °C to 27 °C with drop of 6.9 %.

Principles of TRIP Steel Optimization for Passive Damping Applications

NASA Astrophysics Data System (ADS)

Fraley, George Jay

Globally many historic structures of cultural significance which do not have systems to mitigate seismic damage are located in areas with heavy seismic activity. Efforts have been undertaken to develop strategies to retrofit such structures, however any intervention must be limited in size for aesthetic reasons. To contribute to this effort, ArcelorMittal aims to create steel-based solutions for passive energy dissipation through plastic deformation during cyclic loading. High-strength TRansformation-Induced Plasticity (TRIP) steels are proposed as an excellent candidate material for this application, due to the extreme combination of high strength and large ductility they are well-known to exhibit. To evaluate high-strength TRIP steels for passive damping applications, isothermal, fully-reversed, displacement-controlled Ultra-Low Cycle Fatigue (ULCF) experiments (Nf < 100) were conducted on two tempering conditions of austenitic BlastAlloy (BA) TRIP 180. One tempering condition resulted in a Mssigma temperature of 27 °C and stress-assisted martensitic nucleation, and the other a Mssigma temperature of -8 °C and strain-induced martensitic nucleation at room temperature. The higher austenite stability condition (Ms sigma = -8 °C) was found to have approximately twice the fatigue life and a lower rate of cyclic hardening at fixed displacement amplitudes for low to intermediate levels of plastic strain range (2-10%) compared to the lower stability austenite condition (Mssigma = 27 °C). However, at higher levels of plastic straining (10-16% strain range) the fatigue lives and strain hardening behavior converged for the two stabilities, indicating a likely exhaustion of transformation during the first few cycles. ULCF life behavior for the high-stability austenite condition compared favorably with literature values for structural stainless steel 316, despite having a yield strength approximately four times larger. For a similar number of cycles to failure the high

A solenoid failure detection system for cold gas attitude control jet valves

NASA Technical Reports Server (NTRS)

Johnston, P. A.

1970-01-01

The development of a solenoid valve failure detection system is described. The technique requires the addition of a radioactive gas to the propellant of a cold gas jet attitude control system. Solenoid failure is detected with an avalanche radiation detector located in the jet nozzle which senses the radiation emitted by the leaking radioactive gas. Measurements of carbon monoxide leakage rates through a Mariner type solenoid valve are presented as a function of gas activity and detector configuration. A cylindrical avalanche detector with a factor of 40 improvement in leak sensitivity is proposed for flight systems because it allows the quantity of radioactive gas that must be added to the propellant to be reduced to a practical level.

Thermal System Verification and Model Validation for NASA's Cryogenic Passively Cooled James Webb Space Telescope

NASA Technical Reports Server (NTRS)

Cleveland, Paul E.; Parrish, Keith A.

2005-01-01

A thorough and unique thermal verification and model validation plan has been developed for NASA s James Webb Space Telescope. The JWST observatory consists of a large deployed aperture optical telescope passively cooled to below 50 Kelvin along with a suite of several instruments passively and actively cooled to below 37 Kelvin and 7 Kelvin, respectively. Passive cooling to these extremely low temperatures is made feasible by the use of a large deployed high efficiency sunshield and an orbit location at the L2 Lagrange point. Another enabling feature is the scale or size of the observatory that allows for large radiator sizes that are compatible with the expected power dissipation of the instruments and large format Mercury Cadmium Telluride (HgCdTe) detector arrays. This passive cooling concept is simple, reliable, and mission enabling when compared to the alternatives of mechanical coolers and stored cryogens. However, these same large scale observatory features, which make passive cooling viable, also prevent the typical flight configuration fully-deployed thermal balance test that is the keystone to most space missions thermal verification plan. JWST is simply too large in its deployed configuration to be properly thermal balance tested in the facilities that currently exist. This reality, when combined with a mission thermal concept with little to no flight heritage, has necessitated the need for a unique and alternative approach to thermal system verification and model validation. This paper describes the thermal verification and model validation plan that has been developed for JWST. The plan relies on judicious use of cryogenic and thermal design margin, a completely independent thermal modeling cross check utilizing different analysis teams and software packages, and finally, a comprehensive set of thermal tests that occur at different levels of JWST assembly. After a brief description of the JWST mission and thermal architecture, a detailed description

The Failure Envelope Concept Applied To The Bone-Dental Implant System.

PubMed

Korabi, R; Shemtov-Yona, K; Dorogoy, A; Rittel, D

2017-05-17

Dental implants interact with the jawbone through their common interface. While the implant is an inert structure, the jawbone is a living one that reacts to mechanical stimuli. Setting aside mechanical failure considerations of the implant, the bone is the main component to be addressed. With most failure criteria being expressed in terms of stress or strain values, their fulfillment can mean structural flow or fracture. However, in addition to those effects, the bony structure is likely to react biologically to the applied loads by dissolution or remodeling, so that additional (strain-based) criteria must be taken into account. While the literature abounds in studies of particular loading configurations, e.g. angle and value of the applied load to the implant, a general study of the admissible implant loads is still missing. This paper introduces the concept of failure envelopes for the dental implant-jawbone system, thereby defining admissible combinations of vertical and lateral loads for various failure criteria of the jawbone. Those envelopes are compared in terms of conservatism, thereby providing a systematic comparison of the various failure criteria and their determination of the admissible loads.

29 CFR 1602.43 - Commission's remedy for school systems' or districts' failure to file report.

Code of Federal Regulations, 2013 CFR

2013-07-01

...' failure to file report. Any school system or district failing or refusing to file report EEO-5 when... 29 Labor 4 2013-07-01 2013-07-01 false Commission's remedy for school systems' or districts' failure to file report. 1602.43 Section 1602.43 Labor Regulations Relating to Labor (Continued) EQUAL...

29 CFR 1602.43 - Commission's remedy for school systems' or districts' failure to file report.

Code of Federal Regulations, 2011 CFR

2011-07-01

...' failure to file report. Any school system or district failing or refusing to file report EEO-5 when... 29 Labor 4 2011-07-01 2011-07-01 false Commission's remedy for school systems' or districts' failure to file report. 1602.43 Section 1602.43 Labor Regulations Relating to Labor (Continued) EQUAL...

29 CFR 1602.43 - Commission's remedy for school systems' or districts' failure to file report.

Code of Federal Regulations, 2012 CFR

2012-07-01

...' failure to file report. Any school system or district failing or refusing to file report EEO-5 when... 29 Labor 4 2012-07-01 2012-07-01 false Commission's remedy for school systems' or districts' failure to file report. 1602.43 Section 1602.43 Labor Regulations Relating to Labor (Continued) EQUAL...

29 CFR 1602.43 - Commission's remedy for school systems' or districts' failure to file report.

Code of Federal Regulations, 2014 CFR

2014-07-01

...' failure to file report. Any school system or district failing or refusing to file report EEO-5 when... 29 Labor 4 2014-07-01 2014-07-01 false Commission's remedy for school systems' or districts' failure to file report. 1602.43 Section 1602.43 Labor Regulations Relating to Labor (Continued) EQUAL...

29 CFR 1602.43 - Commission's remedy for school systems' or districts' failure to file report.

Code of Federal Regulations, 2010 CFR

2010-07-01

...' failure to file report. Any school system or district failing or refusing to file report EEO-5 when... 29 Labor 4 2010-07-01 2010-07-01 false Commission's remedy for school systems' or districts' failure to file report. 1602.43 Section 1602.43 Labor Regulations Relating to Labor (Continued) EQUAL...

Optimizing the robustness of electrical power systems against cascading failures.

PubMed

Zhang, Yingrui; Yağan, Osman

2016-06-21

Electrical power systems are one of the most important infrastructures that support our society. However, their vulnerabilities have raised great concern recently due to several large-scale blackouts around the world. In this paper, we investigate the robustness of power systems against cascading failures initiated by a random attack. This is done under a simple yet useful model based on global and equal redistribution of load upon failures. We provide a comprehensive understanding of system robustness under this model by (i) deriving an expression for the final system size as a function of the size of initial attacks; (ii) deriving the critical attack size after which system breaks down completely; (iii) showing that complete system breakdown takes place through a first-order (i.e., discontinuous) transition in terms of the attack size; and (iv) establishing the optimal load-capacity distribution that maximizes robustness. In particular, we show that robustness is maximized when the difference between the capacity and initial load is the same for all lines; i.e., when all lines have the same redundant space regardless of their initial load. This is in contrast with the intuitive and commonly used setting where capacity of a line is a fixed factor of its initial load.

Space Shuttle Main Propulsion System Gaseous Hydrogen Flow Control Valve Poppet Failure

NASA Technical Reports Server (NTRS)

Zeitler, Rick

2010-01-01

The presentation provides background information pertinent to the MPS GH2 Flow Control Valve Poppet failure which occurred on the Space Shuttle Endeavour during STS-126 flight. The presentation provides general MPS system operating information which is pertinent to understanding the failure causes and affects. The presentation provides additional background information on the operating environment in which the FCV functions and basic design history of the flow control valve. The presentation provides an overview of the possible flight failure modes and a brief summary of the flight rationale which was developed for this failure event. This presentation is an introductory presentation to 3 other speakers at the conference who will be speaking on M&P aspects of the investigation, non destructive inspection techniques development, and particle impact testing.

Comparative Evaluation of Periodontal Status of Chronic Renal Failure Patients and Systemically Healthy Individuals.

PubMed

Gupta, Radhika; Kumar, Uttam; Mallapragada, Siddharth; Agarwal, Pallavi

2018-03-01

Periodontitis, a chronic infectious disease, affects most of the population at one time or the other and its expression is a combination of hosts, microbial agents, and environmental factors. Extensive literature exists for the relationship between periodontal disease and diabetes mellitus, cardiovascular diseases, and adverse pregnancy outcomes. Only a few studies performed in a limited number of patients have reported peri-odontal health status in chronic renal failure patients. Hence, the aim of the present study is to assess and compare the periodontal status of patients with chronic renal failure undergoing dialysis, predialysis with systemically healthy individuals. A total of 90 patients were divided into three groups. Group I: 30 renal dialysis patients. Group II: 30 predialysis patients. Control group comprised 30 systemically healthy patients who formed group III. Periodontal examination was carried out using oral hygiene index-simplified (OHI-S), plaque index (PI), gingival index (GI), probing depth, and clinical attachment loss. The results of the study showed that the periodontal status of patients with chronic renal failure undergoing dialysis (dialysis group) and patients with chronic renal failure not undergoing renal dialysis (predialysis) when compared with systemically healthy subjects showed significantly higher mean scores of OHI-S, PI, and clinical attachment loss. Thus, patients with chronic renal failure showed poor oral hygiene and higher prevalence of periodontal disease. The dental community's awareness of implications of poor health within chronic renal failure patients should be elevated.

Lunar Module Environmental Control System Design Considerations and Failure Modes. Part 2

NASA Technical Reports Server (NTRS)

Interbartolo, Michael A.

2009-01-01

This viewgraph presentation seeks to describe the Lunar Module Environmental Control System (ECS) subsystem testing and redesign and seeks to summarize the in-flight failures of the Lunar Module (LM) Environmental Control System (ECS).

Passive magnetic shielding in MRI-Linac systems.

PubMed

Whelan, Brendan; Kolling, Stefan; Oborn, Brad M; Keall, Paul

2018-03-26

Passive magnetic shielding refers to the use of ferromagnetic materials to redirect magnetic field lines away from vulnerable regions. An application of particular interest to the medical physics community is shielding in MRI systems, especially integrated MRI-linear accelerator (MRI-Linac) systems. In these systems, the goal is not only to minimize the magnetic field in some volume, but also to minimize the impact of the shield on the magnetic fields within the imaging volume of the MRI scanner. In this work, finite element modelling was used to assess the shielding of a side coupled 6 MV linac and resultant heterogeneity induced within the 30 cm diameter of spherical volume (DSV) of a novel 1 Tesla split bore MRI magnet. A number of different shield parameters were investigated; distance between shield and magnet, shield shape, shield thickness, shield length, openings in the shield, number of concentric layers, spacing between each layer, and shield material. Both the in-line and perpendicular MRI-Linac configurations were studied. By modifying the shield shape around the linac from the starting design of an open ended cylinder, the shielding effect was boosted by approximately 70% whilst the impact on the magnet was simultaneously reduced by approximately 10%. Openings in the shield for the RF port and beam exit were substantial sources of field leakage; however it was demonstrated that shielding could be added around these openings to compensate for this leakage. Layering multiple concentric shield shells was highly effective in the perpendicular configuration, but less so for the in-line configuration. Cautious use of high permeability materials such as Mu-metal can greatly increase the shielding performance in some scenarios. In the perpendicular configuration, magnetic shielding was more effective and the impact on the magnet lower compared with the in-line configuration.

Passive magnetic shielding in MRI-Linac systems

NASA Astrophysics Data System (ADS)

Whelan, Brendan; Kolling, Stefan; Oborn, Brad M.; Keall, Paul

2018-04-01

Passive magnetic shielding refers to the use of ferromagnetic materials to redirect magnetic field lines away from vulnerable regions. An application of particular interest to the medical physics community is shielding in MRI systems, especially integrated MRI-linear accelerator (MRI-Linac) systems. In these systems, the goal is not only to minimize the magnetic field in some volume, but also to minimize the impact of the shield on the magnetic fields within the imaging volume of the MRI scanner. In this work, finite element modelling was used to assess the shielding of a side coupled 6 MV linac and resultant heterogeneity induced within the 30 cm diameter of spherical volume (DSV) of a novel 1 Tesla split bore MRI magnet. A number of different shield parameters were investigated; distance between shield and magnet, shield shape, shield thickness, shield length, openings in the shield, number of concentric layers, spacing between each layer, and shield material. Both the in-line and perpendicular MRI-Linac configurations were studied. By modifying the shield shape around the linac from the starting design of an open ended cylinder, the shielding effect was boosted by approximately 70% whilst the impact on the magnet was simultaneously reduced by approximately 10%. Openings in the shield for the RF port and beam exit were substantial sources of field leakage; however it was demonstrated that shielding could be added around these openings to compensate for this leakage. Layering multiple concentric shield shells was highly effective in the perpendicular configuration, but less so for the in-line configuration. Cautious use of high permeability materials such as Mu-metal can greatly increase the shielding performance in some scenarios. In the perpendicular configuration, magnetic shielding was more effective and the impact on the magnet lower compared with the in-line configuration.

A Probabilistic Assessment of Failure for Air Force Building Systems

DTIC Science & Technology

2015-03-26

Rain Water Drainage System 1.000 0.225 0.085 0.424 0.800 0.968 0.998 4.449 D209001 Special Piping Systems 0.436 0.088 0.289 0.881 0.998 1.000 1.000...Rain Water Drainage 0.522 D2090 Other Plumbing Systems 0.303 D 30 H V A C D3010 Energy Supply 0.316 D3020 Heat Generating Systems 0.636 D3030...A PROBABILISTIC ASSESSMENT OF FAILURE FOR AIR FORCE BUILDING SYSTEMS THESIS Stephanie L

Passive chevron replicator

NASA Technical Reports Server (NTRS)

Oeffinger, Thomas R. (Inventor); Tocci, Leonard R. (Inventor)

1977-01-01

There is described a passive replicator device to be used in magnetic bubble domain systems. The replicator is passive, i.e., does not require an active element such as a current source or the like, and both propagates and replicates bubble domains. In a preferred embodiment, the replicator uses chevron type elements arranged in an appropriate pattern so as to interact with a pair of propagation paths wherein bubble domains are propagated. A bubble in one propagation path is routinely transferred therealong and, concurrently, replicated by the instant device into another propagation path. A plurality of elements arranged in juxtaposition to the chevrons assists in controlling the propagation of the bubbles through the respective propagation paths and, at the appropriate time, provides a cutting action wherein a bubble which is elongated between the chevrons of the two propagation paths is split into two separate bubbles.

48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Identification (RFID) using passive tags. 552.211-92 Section 552.211-92 Federal Acquisition Regulations System... Provisions and Clauses 552.211-92 Radio Frequency Identification (RFID) using passive tags. As prescribed in 511.204(b)(11), insert the following clause: Radio Frequency Identification (RFID) Using Passive Tags...

48 CFR 552.211-92 - Radio Frequency Identification (RFID) using passive tags.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Identification (RFID) using passive tags. 552.211-92 Section 552.211-92 Federal Acquisition Regulations System... Provisions and Clauses 552.211-92 Radio Frequency Identification (RFID) using passive tags. As prescribed in 511.204(b)(11), insert the following clause: Radio Frequency Identification (RFID) Using Passive Tags...

Wireless SAW passive tag temperature measurement in the collision case

NASA Astrophysics Data System (ADS)

Sorokin, A.; Shepeta, A.; Wattimena, M.

2018-04-01

This paper describes temperature measurement in the multisensor systems based on the radio-frequency identification SAW passive tags which are currently applied in the electric power systems and the switchgears. Different approaches of temperature measurement in the collision case are shown here. The study is based on the tag model with specific topology, which allows us to determine temperature through the response signal with time-frequency information. This research considers the collision case for several passive tags as the temperature sensors which are placed in the switchgear. This research proposal is to analyze the possibility of using several SAW passive sensors in the collision case. We consider the using of the different typical elements for passive surface acoustic wave tag which applies as an anticollision passive sensor. These wireless sensors based on the surface acoustic waves tags contain specifically coded structures. This topology makes possible the reliability of increasing tag identification and the temperature measurement in the collision case. As the results for this case we illustrate simultaneous measurement of at least six sensors.

WiFi-Based Real-Time Calibration-Free Passive Human Motion Detection.

PubMed

Gong, Liangyi; Yang, Wu; Man, Dapeng; Dong, Guozhong; Yu, Miao; Lv, Jiguang

2015-12-21

With the rapid development of WLAN technology, wireless device-free passive human detection becomes a newly-developing technique and holds more potential to worldwide and ubiquitous smart applications. Recently, indoor fine-grained device-free passive human motion detection based on the PHY layer information is rapidly developed. Previous wireless device-free passive human detection systems either rely on deploying specialized systems with dense transmitter-receiver links or elaborate off-line training process, which blocks rapid deployment and weakens system robustness. In the paper, we explore to research a novel fine-grained real-time calibration-free device-free passive human motion via physical layer information, which is independent of indoor scenarios and needs no prior-calibration and normal profile. We investigate sensitivities of amplitude and phase to human motion, and discover that phase feature is more sensitive to human motion, especially to slow human motion. Aiming at lightweight and robust device-free passive human motion detection, we develop two novel and practical schemes: short-term averaged variance ratio (SVR) and long-term averaged variance ratio (LVR). We realize system design with commercial WiFi devices and evaluate it in typical multipath-rich indoor scenarios. As demonstrated in the experiments, our approach can achieve a high detection rate and low false positive rate.

Fuzzy Adaptive Compensation Control of Uncertain Stochastic Nonlinear Systems With Actuator Failures and Input Hysteresis.

PubMed

Wang, Jianhui; Liu, Zhi; Chen, C L Philip; Zhang, Yun

2017-10-12

Hysteresis exists ubiquitously in physical actuators. Besides, actuator failures/faults may also occur in practice. Both effects would deteriorate the transient tracking performance, and even trigger instability. In this paper, we consider the problem of compensating for actuator failures and input hysteresis by proposing a fuzzy control scheme for stochastic nonlinear systems. Compared with the existing research on stochastic nonlinear uncertain systems, it is found that how to guarantee a prescribed transient tracking performance when taking into account actuator failures and hysteresis simultaneously also remains to be answered. Our proposed control scheme is designed on the basis of the fuzzy logic system and backstepping techniques for this purpose. It is proven that all the signals remain bounded and the tracking error is ensured to be within a preestablished bound with the failures of hysteretic actuator. Finally, simulations are provided to illustrate the effectiveness of the obtained theoretical results.

Reliability and sensitivity analysis of a system with multiple unreliable service stations and standby switching failures

NASA Astrophysics Data System (ADS)

Ke, Jyh-Bin; Lee, Wen-Chiung; Wang, Kuo-Hsiung

2007-07-01

This paper presents the reliability and sensitivity analysis of a system with M primary units, W warm standby units, and R unreliable service stations where warm standby units switching to the primary state might fail. Failure times of primary and warm standby units are assumed to have exponential distributions, and service times of the failed units are exponentially distributed. In addition, breakdown times and repair times of the service stations also follow exponential distributions. Expressions for system reliability, RY(t), and mean time to system failure, MTTF are derived. Sensitivity analysis, relative sensitivity analysis of the system reliability and the mean time to failure, with respect to system parameters are also investigated.

Energetic Passivity of the Human Ankle Joint.

PubMed

Lee, Hyunglae; Hogan, Neville

2016-12-01

Understanding the passive or nonpassive behavior of the neuromuscular system is important to design and control robots that physically interact with humans, since it provides quantitative information to secure coupled stability while maximizing performance. This has become more important than ever apace with the increasing demand for robotic technologies in neurorehabilitation. This paper presents a quantitative characterization of passive and nonpassive behavior of the ankle of young healthy subjects, which provides a baseline for future studies in persons with neurological impairments and information for future developments of rehabilitation robots, such as exoskeletal devices and powered prostheses. Measurements using a wearable ankle robot actuating 2 degrees-of-freedom of the ankle combined with curl analysis and passivity analysis enabled characterization of both quasi-static and steady-state dynamic behavior of the ankle, unavailable from single DOF studies. Despite active neuromuscular control over a wide range of muscle activation, in young healthy subjects passive or dissipative ankle behavior predominated.

Sound localization with communications headsets: comparison of passive and active systems.

PubMed

Abel, Sharon M; Tsang, Suzanne; Boyne, Stephen

2007-01-01

Studies have demonstrated that conventional hearing protectors interfere with sound localization. This research examines possible benefits from advanced communications devices. Horizontal plane sound localization was compared in normal-hearing males with the ears unoccluded and fitted with Peltor H10A passive attenuation earmuffs, Racal Slimgard II communications muffs in active noise reduction (ANR) and talk-through-circuitry (TTC) modes and Nacre QUIETPRO TM communications earplugs in off (passive attenuation) and push-to-talk (PTT) modes. Localization was assessed using an array of eight loudspeakers, two in each spatial quadrant. The stimulus was 75 dB SPL, 300-ms broadband noise. One block of 120 forced-choice loudspeaker identification trials was presented in each condition. Subjects responded using a laptop response box with a set of eight microswitches in the same configuration as the speaker array. A repeated measures ANOVA was applied to the dataset. The results reveal that the overall percent correct response was highest in the unoccluded condition (94%). A significant reduction of 24% was observed for the communications devices in TTC and PTT modes and a reduction of 49% for the passive muff and plug and muff with ANR. Disruption in performance was due to an increase in front-back reversal errors for mirror image spatial positions. The results support the conclusion that communications devices with advanced technologies are less detrimental to directional hearing than conventional, passive, limited amplification and ANR devices.

Passive synthetic aperture radar imaging of ground moving targets

NASA Astrophysics Data System (ADS)

Wacks, Steven; Yazici, Birsen

2012-05-01

In this paper we present a method for imaging ground moving targets using passive synthetic aperture radar. A passive radar imaging system uses small, mobile receivers that do not radiate any energy. For these reasons, passive imaging systems result in signicant cost, manufacturing, and stealth advantages. The received signals are obtained by multiple airborne receivers collecting scattered waves due to illuminating sources of opportunity such as commercial television, radio, and cell phone towers. We describe a novel forward model and a corresponding ltered-backprojection type image reconstruction method combined with entropy optimization. Our method determines the location and velocity of multiple targets moving at dierent velocities. Furthermore, it can accommodate arbitrary imaging geometries. we present numerical simulations to verify the imaging method.

Passive solar design strategies: Remodeling guidelines for conserving energy at home

NASA Astrophysics Data System (ADS)

The idea of passive solar is simple, but applying it effectively does require information and attention to the details of design and construction. Some passive solar techniques are modest and low-cost, and require only small changes in remodeler's typical practice. At the other end of the spectrum, some passive solar systems can almost eliminate a house's need for purchased heating (and in some cases, cooling) energy - but probably at a relatively high first cost. In between are a broad range of energy-conserving passive solar techniques. Whether or not they are cost-effective, practical, and attractive enough to offer a market advantage to any individual remodeler depends on very specific factors such as local costs, climate, and market characteristics. Passive Solar Design Strategies: Remodeling Guidelines For Conserving Energy At Home is written to help give remodelers the information they need to make these decisions. Passive Solar Design Strategies is a package in three basic parts: the guidelines contain information about passive solar techniques and how they work, and provides specific examples of systems which will save various percentages of energy; the worksheets offer a simple, fill-in-the-blank method to pre-evaluate the performance of a specific design; and the worked example demonstrates how to complete the worksheets for a typical residence.

Hybrid neural intelligent system to predict business failure in small-to-medium-size enterprises.

PubMed

Borrajo, M Lourdes; Baruque, Bruno; Corchado, Emilio; Bajo, Javier; Corchado, Juan M

2011-08-01

During the last years there has been a growing need of developing innovative tools that can help small to medium sized enterprises to predict business failure as well as financial crisis. In this study we present a novel hybrid intelligent system aimed at monitoring the modus operandi of the companies and predicting possible failures. This system is implemented by means of a neural-based multi-agent system that models the different actors of the companies as agents. The core of the multi-agent system is a type of agent that incorporates a case-based reasoning system and automates the business control process and failure prediction. The stages of the case-based reasoning system are implemented by means of web services: the retrieval stage uses an innovative weighted voting summarization of self-organizing maps ensembles-based method and the reuse stage is implemented by means of a radial basis function neural network. An initial prototype was developed and the results obtained related to small and medium enterprises in a real scenario are presented.

Quantitative Frequency-Domain Passive Cavitation Imaging

PubMed Central

Haworth, Kevin J.; Bader, Kenneth B.; Rich, Kyle T.; Holland, Christy K.; Mast, T. Douglas

2017-01-01

Passive cavitation detection has been an instrumental technique for measuring cavitation dynamics, elucidating concomitant bioeffects, and guiding ultrasound therapies. Recently, techniques have been developed to create images of cavitation activity to provide investigators with a more complete set of information. These techniques use arrays to record and subsequently beamform received cavitation emissions, rather than processing emissions received on a single-element transducer. In this paper, the methods for performing frequency-domain delay, sum, and integrate passive imaging are outlined. The method can be applied to any passively acquired acoustic scattering or emissions, including cavitation emissions. In order to compare data across different systems, techniques for normalizing Fourier transformed data and converting the data to the acoustic energy received by the array are described. A discussion of hardware requirements and alternative imaging approaches are additionally outlined. Examples are provided in MATLAB. PMID:27992331

Combined Active and Passive Solar Space Heating and Solar Hot Water Systems for an Elementary School in Boise, Idaho.

ERIC Educational Resources Information Center

Smull, Neil A.; Armstrong, Gerald L.

1979-01-01

Amity Elementary School in Boise, Idaho, features a solar space heating and domestic hot water system along with an earth covering to accommodate the passive aspects of energy conservation. (Author/MLF)

Passive Containment DataSet

EPA Pesticide Factsheets

This data is for Figures 6 and 7 in the journal article. The data also includes the two EPANET input files used for the analysis described in the paper, one for the looped system and one for the block system.This dataset is associated with the following publication:Grayman, W., R. Murray , and D. Savic. Redesign of Water Distribution Systems for Passive Containment of Contamination. JOURNAL OF THE AMERICAN WATER WORKS ASSOCIATION. American Water Works Association, Denver, CO, USA, 108(7): 381-391, (2016).

Municipal waste stabilization in a reactor with an integrated active and passive aeration system.

PubMed

Kasinski, Slawomir; Slota, Monika; Markowski, Michal; Kaminska, Anna

2016-04-01

To test whether an integrated passive and active aeration system could be an effective solution for aerobic decomposition of municipal waste in technical conditions, a full-scale composting reactor was designed. The waste was actively aerated for 5d, passively aerated for 35 d, and then actively aerated for 5d, and the entire composting process was monitored. During the 45-day observation period, changes in the fractional, morphological and physico-chemical characteristics of the waste at the top of the reactor differed from those in the center of the reactor. The fractional and morphological analysis made during the entire process of stabilization, showed the total reduction of organic matter measured of 82 wt% and 86 wt% at the respective depths. The reduction of organic matter calculated using the results of Lost of Ignition (LOI) and Total Organic Carbon (TOC) showed, respectively, 40.51-46.62% organic matter loss at the top and 45.33-53.39% in the center of the reactor. At the end of the process, moisture content, LOI and TOC at the top were 3.29%, 6.10% and 4.13% higher, respectively, than in the center. The results showed that application of passive aeration in larger scale simultaneously allows the thermophilic levels to be maintained during municipal solid waste composting process while not inhibiting microbial activity in the reactor. Copyright © 2016 Elsevier Ltd. All rights reserved.

(n, N) type maintenance policy for multi-component systems with failure interactions

NASA Astrophysics Data System (ADS)

Zhang, Zhuoqi; Wu, Su; Li, Binfeng; Lee, Seungchul

2015-04-01

This paper studies maintenance policies for multi-component systems in which failure interactions and opportunistic maintenance (OM) involve. This maintenance problem can be formulated as a Markov decision process (MDP). However, since an action set and state space in MDP exponentially expand as the number of components increase, traditional approaches are computationally intractable. To deal with curse of dimensionality, we decompose such a multi-component system into mutually influential single-component systems. Each single-component system is formulated as an MDP with the objective of minimising its long-run average maintenance cost. Under some reasonable assumptions, we prove the existence of the optimal (n, N) type policy for a single-component system. An algorithm to obtain the optimal (n, N) type policy is also proposed. Based on the proposed algorithm, we develop an iterative approximation algorithm to obtain an acceptable maintenance policy for a multi-component system. Numerical examples find that failure interactions and OM pose significant effects on a maintenance policy.

Nonparametric method for failures diagnosis in the actuating subsystem of aircraft control system

NASA Astrophysics Data System (ADS)

Terentev, M. N.; Karpenko, S. S.; Zybin, E. Yu; Kosyanchuk, V. V.

2018-02-01

In this paper we design a nonparametric method for failures diagnosis in the aircraft control system that uses the measurements of the control signals and the aircraft states only. It doesn’t require a priori information of the aircraft model parameters, training or statistical calculations, and is based on analytical nonparametric one-step-ahead state prediction approach. This makes it possible to predict the behavior of unidentified and failure dynamic systems, to weaken the requirements to control signals, and to reduce the diagnostic time and problem complexity.

Reflection Paper on a Ubiquitous English Vocabulary Learning System: Evidence of Active/Passive Attitude vs. Usefulness/Ease-of-Use

ERIC Educational Resources Information Center

Lim, Jeff

2013-01-01

"A ubiquitous English vocabulary learning system: evidence of active/passive attitudes vs. usefulness/ease-of-use" introduces and develops "Ubiquitous English Vocabulary Learning" (UEFL) system. It introduces to the memorization using the video clips. According to their paper the video clip gives a better chance for students to…

Optical heterodyne accelerometry: passively stabilized, fully balanced velocity interferometer system for any reflector

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

Buttler, William T.; Lamoreaux, Steven K.

2010-08-10

We formalize the physics of an optical heterodyne accelerometer that allows measurement of low and high velocities from material surfaces under high strain. The proposed apparatus incorporates currently common optical velocimetry techniques used in shock physics, with interferometric techniques developed to self-stabilize and passively balance interferometers in quantum cryptography. The result is a robust telecom-fiber-based velocimetry system insensitive to modal and frequency dispersion that should work well in the presence of decoherent scattering processes, such as from ejecta clouds and shocked surfaces.

Turbiditic systems on passive margins: fifteen years of fruitful industry-academic exchanges.

NASA Astrophysics Data System (ADS)

Guillocheau, F.

2012-04-01

During the last fifteen years, with the oil discovery in deep offshore plays, new tools have been developed that deeply modified our knowledge on sedimentary gravity processes on passive margins: geometry, physical processes, but also the importance of the topography and the quantification of the stratigraphic parameters of control. The major breakthrough was of course the extensive 3D seismic data available around most of the world margins with a focus on gravity-tectonics dominated margins. The first major progress was the characterization of the sinuous channels infilling, their diversity and different models for their origin. This also was a better knowledge of the different types of slopes (graded vs. above-graded) and the extension of the concept of accommodation to deep-water environments (ponded, healed-slope, incised submarine valley and slope accommodation). The second step was the understanding of the synsedimentary deformations for the location and the growth of turbiditic systems on margins dominated by gravity tectonics, with the importance of the sedimentary flux and its variation through time and space. The third step is now the integration of the sedimentary system, from the upstream erosional catchment to the abyssal plain (source to sink approach), with the question of the sediment routing system. During the last 100 Ma, continents experienced major changes of both topography and climate. In the case of Africa, those are (1) the growth of the plateaus (and mainly the South African one) around 90-80 Ma (Late Cretaceous) and 40-20 Ma (Late Eocene-Early Miocene) and (2) a climate evolution from hot humid (50-40 Ma) to hot dry conditions since 20-15 Ma. This evolution changed the topography, the processes of erosion and the volume and nature (weathered vs. non weathered rocks) materials. Those are primary processes for controlling the deposition of turbiditic systems, and then to predict the location of sands. This will be discussed along the

Renin-angiotensin-aldosterone system (RAAS) pharmacogenomics: implications in heart failure management.

PubMed

Beitelshees, Amber L; Zineh, Issam

2010-05-01

Blockade of the renin-angiotensin-aldosterone system (RAAS) with ACE inhibitors has been a cornerstone of heart failure therapy for over 15 years. More recently, further blockade of RAAS with aldosterone antagonists and angiotensin receptor blockers (ARBs) has been studied. While these therapies have certainly improved outcomes in the treatment of heart failure, morbidity and mortality remain extremely high. Furthermore, polypharmacy and complex regimens of seven medications on average is the norm for management of heart failure. This results in increased costs, patient burden, and uncertainty as to the best course of therapy. The ability to personalize patients' therapeutic regimens using pharmacogenomics has the potential of providing more effective and efficient use of RAAS-modulating medications. This review highlights the implications of major RAAS pharmacogenetic studies, while outlining future directions for translation to practice.

Passive and Active Control of Space Structures (PACOSS)

NASA Astrophysics Data System (ADS)

Morosow, G.; Harcrow, H.; Rogers, L.

1985-04-01

Passive and Active Control of Space Structures (PACOSS) is a five-year program designed to investigate highly damped structures in conjunction with active control systems, and in particular to develop technology that integrates passive damping and active control to achieve precise pointing control. Major areas of research include metal matrix composites; viscoelastic materials; damping devices; dynamic test article design, fabrication and testing; and active damping.

On the importance of measurement system calibration for underwater passive monitoring

NASA Astrophysics Data System (ADS)

Miqueleti, S. A.; Costa-Félix, R. P. B.

2016-07-01

The underwater passive acoustic monitoring of sound in oceans is growing in recent years and has served as a source of information on marine life and the interference of human activities on the environment. The recordings are used for species identification and prevention of potential adverse effects of vessel traffic, sonar and offshore activities as a whole. However, not much attention is given to the calibration of the hydrophone used to ensure the validity of the information collected. The resulting sound depends on the input audio, and the transfer function of the intensity of the input signal. This paper presents an assessment of how the lack of calibration of hydroacoustic systems might compromise the evaluation of the marine environment.

SiC formation for a solar cell passivation layer using an RF magnetron co-sputtering system

PubMed Central

2012-01-01

In this paper, we describe a method of amorphous silicon carbide film formation for a solar cell passivation layer. The film was deposited on p-type silicon (100) and glass substrates by an RF magnetron co-sputtering system using a Si target and a C target at a room-temperature condition. Several different SiC [Si1-xCx] film compositions were achieved by controlling the Si target power with a fixed C target power at 150 W. Then, structural, optical, and electrical properties of the Si1-xCx films were studied. The structural properties were investigated by transmission electron microscopy and secondary ion mass spectrometry. The optical properties were achieved by UV-visible spectroscopy and ellipsometry. The performance of Si1-xCx passivation was explored by carrier lifetime measurement. PMID:22221730

Passive magnetic bearing systems stabilizer/bearing utilizing time-averaging of a periodic magnetic field

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

Post, Richard F.

A high-stiffness stabilizer/bearings for passive magnetic bearing systems is provide where the key to its operation resides in the fact that when the frequency of variation of the repelling forces of the periodic magnet array is large compared to the reciprocal of the growth time of the unstable motion, the rotating system will feel only the time-averaged value of the force. When the time-averaged value of the force is radially repelling by the choice of the geometry of the periodic magnet array, the Earnshaw-related unstable hit motion that would occur at zero rotational speed is suppressed when the system ismore » rotating at operating speeds.« less

Passive solar addition to therapeutic pre-school. Final technical report

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

Not Available

1983-10-01

This project consisted of designing and constructing a passive solar system on a new classroom addition to the Peanut Butter and Jelly Therapeutic Pre-School in Albuquerque, NM. The purpose of this project was to demonstrate the applicability of solar space heating systems to large institutional buildings, and to demonstrate the energy and cost savings available through the use of such systems. Preliminary estimates indicated that the passive solar systems will provide about 90 percent of the heating and cooling needs for the new classroom addition to the school.

Development of a passively Q-switched Nd:YAG microchip laser for use in the Satellite Laser Ranging 2000 project

NASA Astrophysics Data System (ADS)

Gompers, Samuel Leo

Presently, NASA is designing a replacement for its existing satellite laser ranging systems. These systems are used to measure Earth-satellite distances, tectonic plate movement, variations in rotational motion and other geodetic phenomena. Satellite Laser Ranging 2000 (SLR2000) is envisioned as a fully automated, sub- centimeter accuracy, eye-safe, low-cost replacement to the current SLR systems. It is expected to overcome present limitations by operating autonomously; being free of optical, chemical or electrical hazards; and having a greater average time between failures. Expected shot range precision is about one centimeter with normal point precision of better than three centimeters. This system will have twenty-four hour tracking coverage. SLR2000 specifications dictate operation at visible wavelengths with eye-safe energies on the order of one hundred microjoules and repetition rates on the order of two kilohertz. The optical subsystem of SLR2000 includes a passively Q- switched Nd:YAG microlaser. Passive Q-switching will be achieved using a saturable absorber and offers a number of advantages over the mode-locked lasers currently used in ranging stations: no need for long resonators with tight thermal control; no electro-optic switch required for single pulse selection; saturable absorbers precluding the use of carcinogenic dyes and solvents; and RF drive frequency electronics not tied to the resonator length of the laser cavity. The presented work describes the research and development of a prototype laser used to produce the energies, repetition rates and pulsewidths required for SLR2000. Optimization theories and models were applied to the laser design in order to accurately predict and assess performance characteristics of both gain medium and saturable absorber. Data were obtained which illustrated the affect of pump laser saturation and thermal lensing of the gain medium. Important laboratory skills and techniques were acquired in the design and

Passivation process and the mechanism of packing particles in the Fe0/GAC system during the treatment of ABS resin wastewater.

PubMed

Lai, Bo; Zhou, Yuexi; Wang, Juling; Zhang, Yunhong; Chen, Zhiqiang

2014-01-01

This study provides mechanistic insights into the passivation of the packing particles during the treatment of acrylonitrile-butadiene-styrene (ABS) resin wastewater by the Fe0/GAC system. The granular-activated carbon (GAC) and iron chippings (Fe0) were mixed together with a volumetric ratio of 1:1. GAC has a mean particle size of approximately 3-5 mm, a specific surface of 748 m2 g(-1), a total pore volume of 0.48 mL g(-1) and a bulk density of 0.49 g cm(-3). The iron chippings have a compact and non-porous surface morphology. The results show that the packing particles in the Fe0/GAC system would lose their activity because the removal of TOC and PO4(3-) for ABS resin wastewater could not carried out by the Fe0/GAC system after 40 days continuous running. Meanwhile, the availability of O2 and intrinsic reactivity of Fe0 play a key role on the form of passive film with different iron oxidation states. The passive film on the surface of iron chippings was formed by two phases: (a) local corrosion phase (0-20 d) and (b) co-precipitation phase (20-40 d), while that of GAC was mainly formed by the co-precipitation of corrosion products with SO4(2-) and PO4(3-) because SO4(2-) and PO4(3-) would not easily reach the Fe0 surface. Therefore, in order to avoid the occurrence of filler passivation, high concentrations of SO4(2-) and PO4(3-) in wastewater should be removed before the treatment process of the Fe/GAC system.

49 CFR 191.12 - Distribution Systems: Mechanical Fitting Failure Reports

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 3 2011-10-01 2011-10-01 false Distribution Systems: Mechanical Fitting Failure Reports 191.12 Section 191.12 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL AND OTHER...

Reliable Control Using Disturbance Observer and Equivalent Transfer Function for Position Servo System in Current Feedback Loop Failure

NASA Astrophysics Data System (ADS)

Ishikawa, Kaoru; Nakamura, Taro; Osumi, Hisashi

A reliable control method is proposed for multiple loop control system. After a feedback loop failure, such as case of the sensor break down, the control system becomes unstable and has a big fluctuation even if it has a disturbance observer. To cope with this problem, the proposed method uses an equivalent transfer function (ETF) as active redundancy compensation after the loop failure. The ETF is designed so that it does not change the transfer function of the whole system before and after the loop failure. In this paper, the characteristic of reliable control system that uses an ETF and a disturbance observer is examined by the experiment that uses the DC servo motor for the current feedback loop failure in the position servo system.

Method of passivating semiconductor surfaces

DOEpatents

Wanlass, Mark W.

1990-01-01

A method of passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

Risk assessment for Industrial Control Systems quantifying availability using mean failure cost (MFC)

DOE PAGES

Chen, Qian; Abercrombie, Robert K; Sheldon, Frederick T.

2015-09-23

Industrial Control Systems (ICS) are commonly used in industries such as oil and natural gas, transportation, electric, water and wastewater, chemical, pharmaceutical, pulp and paper, food and beverage, as well as discrete manufacturing (e.g., automotive, aerospace, and durable goods.) SCADA systems are generally used to control dispersed assets using centralized data acquisition and supervisory control.Originally, ICS implementations were susceptible primarily to local threats because most of their components were located in physically secure areas (i.e., ICS components were not connected to IT networks or systems). The trend toward integrating ICS systems with IT networks (e.g., efficiency and the Internet ofmore » Things) provides significantly less isolation for ICS from the outside world thus creating greater risk due to external threats. Albeit, the availability of ICS/SCADA systems is critical to assuring safety, security and profitability. Such systems form the backbone of our national cyber-physical infrastructure.Herein, we extend the concept of mean failure cost (MFC) to address quantifying availability to harmonize well with ICS security risk assessment. This new measure is based on the classic formulation of Availability combined with Mean Failure Cost (MFC). Finally, the metric offers a computational basis to estimate the availability of a system in terms of the loss that each stakeholder stands to sustain as a result of security violations or breakdowns (e.g., deliberate malicious failures).« less

Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine

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

Prikhodko, Vitaly Y.; James E. Parks, II; Pihl, Josh A.

Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in oxidizing exhaust. For these lean gasoline engines, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH 3 production via a passivemore » SCR approach is of interest. In a passive SCR system, NH 3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH 3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH 3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH 3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. At an SCR average inlet temperature of 350 °C, an NH 3:NOX ratio of 1.15:1 (achieved through longer rich cycle timing) resulted in 99.7 % NOX conversion. Increasing NH 3 generation further resulted in even higher NOX conversion; however, tailpipe NH 3 emissions resulted. At higher underfloor temperatures, NH 3 oxidation over the SCR limited NH 3 availability for NOX reduction. At the engine conditions studied, greater than 99 % NOX conversion was achieved with passive SCR while

Ammonia Generation and Utilization in a Passive SCR (TWC+SCR) System on Lean Gasoline Engine

DOE PAGES

Prikhodko, Vitaly Y.; James E. Parks, II; Pihl, Josh A.; ...

2016-04-05

Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in oxidizing exhaust. For these lean gasoline engines, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH 3 production via a passivemore » SCR approach is of interest. In a passive SCR system, NH 3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH 3 on the SCR catalyst. In this work, a passive SCR system was evaluated on a 2.0-liter BMW lean burn gasoline direct injection engine to assess NH 3 generation over a Pd-only TWC and utilization over a Cu-based SCR catalyst. System NOX reduction efficiency and fuel efficiency improvement compared to stoichiometric engine operation were measured. A feedback control strategy based on cumulative NH 3 produced by the TWC during rich operation and NOX emissions during lean operation was implemented on the engine to control lean/rich cycle timing. At an SCR average inlet temperature of 350 °C, an NH 3:NOX ratio of 1.15:1 (achieved through longer rich cycle timing) resulted in 99.7 % NOX conversion. Increasing NH 3 generation further resulted in even higher NOX conversion; however, tailpipe NH 3 emissions resulted. At higher underfloor temperatures, NH 3 oxidation over the SCR limited NH 3 availability for NOX reduction. At the engine conditions studied, greater than 99 % NOX conversion was achieved with passive SCR while

Program Helps In Analysis Of Failures

NASA Technical Reports Server (NTRS)

Stevenson, R. W.; Austin, M. E.; Miller, J. G.

1993-01-01

Failure Environment Analysis Tool (FEAT) computer program developed to enable people to see and better understand effects of failures in system. User selects failures from either engineering schematic diagrams or digraph-model graphics, and effects or potential causes of failures highlighted in color on same schematic-diagram or digraph representation. Uses digraph models to answer two questions: What will happen to system if set of failure events occurs? and What are possible causes of set of selected failures? Helps design reviewers understand exactly what redundancies built into system and where there is need to protect weak parts of system or remove them by redesign. Program also useful in operations, where it helps identify causes of failure after they occur. FEAT reduces costs of evaluation of designs, training, and learning how failures propagate through system. Written using Macintosh Programmers Workshop C v3.1. Can be linked with CLIPS 5.0 (MSC-21927, available from COSMIC).

Addition of Passive Dynamics to a Flapping Airfoil to Improve Performance

NASA Astrophysics Data System (ADS)

Asselin, Daniel; Young, Jay; Williamson, C. H. K.

2017-11-01

Animals which fly or swim typically employ flapping motions of their wings and fins in order to produce thrust and to maneuver. Small, unmanned vehicles might also exploit such motions and are of considerable interest for the purposes of surveillance, environmental monitoring, and search and rescue. Flapping refers to a combination of pitch and heave and has been shown to provide good thrust and efficiency (Read, et al. 2003) when both axes are independently controlled (an Active-Active system). In this study, we examine the performance of an airfoil actuated only in the heave direction but allowed to pitch passively under the control of a torsion spring (an Active-Passive system). The presence of the spring is simulated in software using a force-feedback control system called Cyber-Physical Fluid Dynamics, or CPFD (Mackowski & Williamson 2011, 2015, 2016). Adding passive pitch to active heave provides significantly improved thrust and efficiency compared with heaving alone, especially when the torsion spring stiffness is selected so that the system operates near resonance (in an Active-Passive system). In many cases, values of thrust and efficiency are comparable to or better than those obtained with two actively controlled degrees of freedom. By using carefully-designed passive dynamics in the pitch direction, we can eliminate one of the two actuators, saving cost, complexity, and weight, while maintaining performance. This work was supported by the Air Force Office of Scientific Research Grant No. FA9550-15-1-0243, monitored by Dr. Douglas Smith.

Analysis of Failures of High Speed Shaft Bearing System in a Wind Turbine

NASA Astrophysics Data System (ADS)

Wasilczuk, Michał; Gawarkiewicz, Rafał; Bastian, Bartosz

2018-01-01

During the operation of wind turbines with gearbox of traditional configuration, consisting of one planetary stage and two helical stages high failure rate of high speed shaft bearings is observed. Such a high failures frequency is not reflected in the results of standard calculations of bearing durability. Most probably it can be attributed to atypical failure mechanism. The authors studied problems in 1.5 MW wind turbines of one of Polish wind farms. The analysis showed that the problems of high failure rate are commonly met all over the world and that the statistics for the analysed turbines were very similar. After the study of potential failure mechanism and its potential reasons, modification of the existing bearing system was proposed. Various options, with different bearing types were investigated. Different versions were examined for: expected durability increase, extent of necessary gearbox modifications and possibility to solve existing problems in operation.

77 FR 62270 - Proposed Revision Treatment of Non-Safety Systems for Passive Advanced Light Water Reactors

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-12

... for Passive Advanced Light Water Reactors AGENCY: Nuclear Regulatory Commission. ACTION: Standard... Passive Advanced Light Water Reactors.'' The current SRP does not contain guidance on the proposed RTNSS for Passive Advance Light Water Reactors. DATES: Submit comments by November 13, 2012. Comments...

An intelligent control system for failure detection and controller reconfiguration

NASA Technical Reports Server (NTRS)

Biswas, Saroj K.

1994-01-01

We present an architecture of an intelligent restructurable control system to automatically detect failure of system components, assess its impact on system performance and safety, and reconfigure the controller for performance recovery. Fault detection is based on neural network associative memories and pattern classifiers, and is implemented using a multilayer feedforward network. Details of the fault detection network along with simulation results on health monitoring of a dc motor have been presented. Conceptual developments for fault assessment using an expert system and controller reconfiguration using a neural network are outlined.

A passive autofocus system by using standard deviation of the image on a liquid lens

NASA Astrophysics Data System (ADS)

Rasti, Pejman; Kesküla, Arko; Haus, Henry; Schlaak, Helmut F.; Anbarjafari, Gholamreza; Aabloo, Alvo; Kiefer, Rudolf

2015-04-01

Today most of applications have a small camera such as cell phones, tablets and medical devices. A micro lens is required in order to reduce the size of the devices. In this paper an auto focus system is used in order to find the best position of a liquid lens without any active components such as ultrasonic or infrared. In fact a passive auto focus system by using standard deviation of the images on a liquid lens which consist of a Dielectric Elastomer Actuator (DEA) membrane between oil and water is proposed.

Poster - Thur Eve - 05: Safety systems and failure modes and effects analysis for a magnetic resonance image guided radiation therapy system.

PubMed

Lamey, M; Carlone, M; Alasti, H; Bissonnette, J P; Borg, J; Breen, S; Coolens, C; Heaton, R; Islam, M; van Proojen, M; Sharpe, M; Stanescu, T; Jaffray, D

2012-07-01

An online Magnetic Resonance guided Radiation Therapy (MRgRT) system is under development. The system is comprised of an MRI with the capability of travel between and into HDR brachytherapy and external beam radiation therapy vaults. The system will provide on-line MR images immediately prior to radiation therapy. The MR images will be registered to a planning image and used for image guidance. With the intention of system safety we have performed a failure modes and effects analysis. A process tree of the facility function was developed. Using the process tree as well as an initial design of the facility as guidelines possible failure modes were identified, for each of these failure modes root causes were identified. For each possible failure the assignment of severity, detectability and occurrence scores was performed. Finally suggestions were developed to reduce the possibility of an event. The process tree consists of nine main inputs and each of these main inputs consisted of 5 - 10 sub inputs and tertiary inputs were also defined. The process tree ensures that the overall safety of the system has been considered. Several possible failure modes were identified and were relevant to the design, construction, commissioning and operating phases of the facility. The utility of the analysis can be seen in that it has spawned projects prior to installation and has lead to suggestions in the design of the facility. © 2012 American Association of Physicists in Medicine.

Method of passivating semiconductor surfaces

DOEpatents

Wanlass, M.W.

1990-06-19

A method is described for passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

Model predictive control of a lean-burn gasoline engine coupled with a passive selective catalytic reduction system

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

Chen, Pingen; Lin, Qinghua; Prikhodko, Vitaly Y.

Lean-burn gasoline engines have demonstrated 10–20% engine efficiency gain over stoichiometric engines and are widely considered as a promising technology for meeting the 54.5 miles-per-gallon (mpg) Corporate Average Fuel Economy standard by 2025. Nevertheless, NOx emissions control for lean-burn gasoline for meeting the stringent EPA Tier 3 emission standards has been one of the main challenges towards the commercialization of highly-efficient lean-burn gasoline engines in the United States. Passive selective catalytic reduction (SCR) systems, which consist of a three-way catalyst and SCR, have demonstrated great potentials of effectively reducing NOx emissions for lean gasoline engines but may cause significant fuelmore » penalty due to ammonia generation via rich engine combustion. The purpose of this study is to develop a model-predictive control (MPC) scheme for a lean-burn gasoline engine coupled with a passive SCR system to minimize the fuel penalty associated with passive SCR operation while satisfying stringent NOx and NH3 emissions requirements. Simulation results demonstrate that the MPC-based control can reduce the fuel penalty by 47.7% in a simulated US06 cycle and 32.0% in a simulated UDDS cycle, compared to the baseline control, while achieving over 96% deNOx efficiency and less than 15 ppm tailpipe ammonia slip. The proposed MPC control can potentially enable high engine efficiency gain for highly-efficient lean-burn gasoline engine while meeting the stringent EPA Tier 3 emission standards.« less

Pathophysiologic Mechanisms in Heart Failure: Role of the Sympathetic Nervous System.

PubMed

Antoine, Steve; Vaidya, Gaurang; Imam, Haider; Villarreal, Daniel

2017-01-01

The syndrome of heart failure involves complex pathophysiologic mechanisms and is associated with extremely high-morbidity, mortality and economic costs. This growing global epidemic has diverse etiologies and is fundamentally characterized by dyshomeostasis between heart and kidneys, leading to development and progression of the cardiorenal syndrome. Excessive and sustained sympathoexcitation has emerged as a single prominent factor involved in the structural and functional dysfunction of multiple organ systems during this disease. Studies in experimental models of heart failure indicate that ablation of the renal nerves may help restore renal sodium and water equilibrium as well as the attenuation of adverse cardiac remodeling. With the recent development of minimally invasive endovascular renal denervation in humans, it is anticipated that this technology would become a novel and important paradigm shift in the management of heart failure. Copyright © 2017. Published by Elsevier Inc.

Passive Education

ERIC Educational Resources Information Center

Bojesen, Emile

2018-01-01

This paper does not present an advocacy of a passive education as opposed to an active education nor does it propose that passive education is in any way 'better' or more important than active education. Through readings of Maurice Blanchot, Jacques Derrida and B.S. Johnson, and gentle critiques of Jacques Rancière and John Dewey, passive…

A mobile system for the improvement of heart failure management: Evaluation of a prototype.

PubMed

Haynes, Sarah C; Kim, Katherine K

2017-01-01

Management of heart failure is complex, often involving interaction with multiple providers, monitoring of symptoms, and numerous medications. Employing principles of user-centered design, we developed a high- fidelity prototype of a mobile system for heart failure self-management and care coordination. Participants, including both heart failure patients and health care providers, tested the mobile system during a one-hour one-on-one session with a facilitator. The facilitator interviewed participants about the strengths and weaknesses of the prototype, necessary features, and willingness to use the technology. We performed a qualitative content analysis using the transcripts of these interviews. Fourteen distinct themes were identified in the analysis. Of these themes, integration, technology literacy, memory, and organization were the most common. Privacy was the least common theme. Our study suggests that this integration is essential for adoption of a mobile system for chronic disease management and care coordination.

Common Cause Failure Modeling

NASA Technical Reports Server (NTRS)

Hark, Frank; Britton, Paul; Ring, Rob; Novack, Steven D.

2016-01-01

Common Cause Failures (CCFs) are a known and documented phenomenon that defeats system redundancy. CCFS are a set of dependent type of failures that can be caused by: system environments; manufacturing; transportation; storage; maintenance; and assembly, as examples. Since there are many factors that contribute to CCFs, the effects can be reduced, but they are difficult to eliminate entirely. Furthermore, failure databases sometimes fail to differentiate between independent and CCF (dependent) failure and data is limited, especially for launch vehicles. The Probabilistic Risk Assessment (PRA) of NASA's Safety and Mission Assurance Directorate at Marshal Space Flight Center (MFSC) is using generic data from the Nuclear Regulatory Commission's database of common cause failures at nuclear power plants to estimate CCF due to the lack of a more appropriate data source. There remains uncertainty in the actual magnitude of the common cause risk estimates for different systems at this stage of the design. Given the limited data about launch vehicle CCF and that launch vehicles are a highly redundant system by design, it is important to make design decisions to account for a range of values for independent and CCFs. When investigating the design of the one-out-of-two component redundant system for launch vehicles, a response surface was constructed to represent the impact of the independent failure rate versus a common cause beta factor effect on a system's failure probability. This presentation will define a CCF and review estimation calculations. It gives a summary of reduction methodologies and a review of examples of historical CCFs. Finally, it presents the response surface and discusses the results of the different CCFs on the reliability of a one-out-of-two system.

Common Cause Failure Modeling

NASA Technical Reports Server (NTRS)

Hark, Frank; Britton, Paul; Ring, Rob; Novack, Steven D.

2015-01-01

Common Cause Failures (CCFs) are a known and documented phenomenon that defeats system redundancy. CCFS are a set of dependent type of failures that can be caused by: system environments; manufacturing; transportation; storage; maintenance; and assembly, as examples. Since there are many factors that contribute to CCFs, the effects can be reduced, but they are difficult to eliminate entirely. Furthermore, failure databases sometimes fail to differentiate between independent and CCF (dependent) failure and data is limited, especially for launch vehicles. The Probabilistic Risk Assessment (PRA) of NASA's Safety and Mission Assurance Directorate at Marshall Space Flight Center (MFSC) is using generic data from the Nuclear Regulatory Commission's database of common cause failures at nuclear power plants to estimate CCF due to the lack of a more appropriate data source. There remains uncertainty in the actual magnitude of the common cause risk estimates for different systems at this stage of the design. Given the limited data about launch vehicle CCF and that launch vehicles are a highly redundant system by design, it is important to make design decisions to account for a range of values for independent and CCFs. When investigating the design of the one-out-of-two component redundant system for launch vehicles, a response surface was constructed to represent the impact of the independent failure rate versus a common cause beta factor effect on a system's failure probability. This presentation will define a CCF and review estimation calculations. It gives a summary of reduction methodologies and a review of examples of historical CCFs. Finally, it presents the response surface and discusses the results of the different CCFs on the reliability of a one-out-of-two system.

Toward Interpreting Failure in Sintered-Silver Interconnection Systems

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

Wereszczak, Andrew A; Waters, Shirley B

2016-01-01

The mechanical strength and subsequent reliability of a sintered-silver interconnection system is a function of numerous independent parameters. That system is still undergoing process development. Most of those parameters (e.g., choice of plating) are arguably and unfortunately taken for granted and are independent of the silver s cohesive strength. To explore such effects, shear strength testing and failure analyses were completed on a simple, mock sintered-silver interconnection system consisting of bonding two DBC ceramic substrates. Silver and gold platings were part of the test matrix, as was pre-drying strategies, and the consideration of stencil-printing vs. screen-printing. Shear strength of sintered-silvermore » interconnect systems was found to be was insensitive to the choice of plating, drying practice, and printing method provided careful and consistent processing of the sintered-silver are practiced. But if the service stress in sintered silver interconnect systems is anticipated to exceed ~ 60 MPa, then the system will likely fail.« less

Combining Radiography and Passive Measurements for Radiological Threat Detection in Cargo

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

Miller, Erin A.; White, Timothy A.; Jarman, Kenneth D.

Abstract Radiography is widely understood to provide information complimentary to passive detection: while not directly sensitive to radiological materials, radiography can reveal highly shielded regions which may mask a passive radiological signal. We present a method for combining radiographic and passive data which uses the radiograph to provide an estimate of scatter and attenuation for possible sources. This approach allows quantitative use of radiographic images without relying on image interpretation, and results in a probabilistic description of likely source locations and strengths. We present first results for this method for a simple modeled test case of a cargo container drivingmore » through a PVT portal. With this inversion approach, we address criteria for an integrated passive and radiographic screening system and how detection of SNM threats might be improved in such a system.« less

WiFi-Based Real-Time Calibration-Free Passive Human Motion Detection †

PubMed Central

Gong, Liangyi; Yang, Wu; Man, Dapeng; Dong, Guozhong; Yu, Miao; Lv, Jiguang

2015-01-01

With the rapid development of WLAN technology, wireless device-free passive human detection becomes a newly-developing technique and holds more potential to worldwide and ubiquitous smart applications. Recently, indoor fine-grained device-free passive human motion detection based on the PHY layer information is rapidly developed. Previous wireless device-free passive human detection systems either rely on deploying specialized systems with dense transmitter-receiver links or elaborate off-line training process, which blocks rapid deployment and weakens system robustness. In the paper, we explore to research a novel fine-grained real-time calibration-free device-free passive human motion via physical layer information, which is independent of indoor scenarios and needs no prior-calibration and normal profile. We investigate sensitivities of amplitude and phase to human motion, and discover that phase feature is more sensitive to human motion, especially to slow human motion. Aiming at lightweight and robust device-free passive human motion detection, we develop two novel and practical schemes: short-term averaged variance ratio (SVR) and long-term averaged variance ratio (LVR). We realize system design with commercial WiFi devices and evaluate it in typical multipath-rich indoor scenarios. As demonstrated in the experiments, our approach can achieve a high detection rate and low false positive rate. PMID:26703612