Science.gov

Sample records for access control layer

  1. A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

    NASA Technical Reports Server (NTRS)

    Wallett, Thomas M.

    2009-01-01

    This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements.

  2. Reflective Database Access Control

    ERIC Educational Resources Information Center

    Olson, Lars E.

    2009-01-01

    "Reflective Database Access Control" (RDBAC) is a model in which a database privilege is expressed as a database query itself, rather than as a static privilege contained in an access control list. RDBAC aids the management of database access controls by improving the expressiveness of policies. However, such policies introduce new interactions…

  3. Improving School Access Control

    ERIC Educational Resources Information Center

    National Clearinghouse for Educational Facilities, 2008

    2008-01-01

    Few things are more important for school safety and security than controlling access to buildings and grounds. It is relatively easy to incorporate effective access control measures in new school designs but more difficult in existing schools, where most building and site features cannot be readily altered or reconfigured. The National…

  4. CAS. Controlled Access Security

    SciTech Connect

    Martinez, B.; Pomeroy, G.

    1989-12-01

    The Security Alarm System is a data acquisition and control system which collects data from intrusion sensors and displays the information in a real-time environment for operators. The Access Control System monitors and controls the movement of personnel with the use of card readers and biometrics hand readers.

  5. Apparatus and method supporting wireless access to multiple security layers in an industrial control and automation system or other system

    DOEpatents

    Chen, Yu-Gene T.

    2013-04-16

    A method includes receiving a message at a first wireless node. The first wireless node is associated with a first wired network, and the first wired network is associated with a first security layer. The method also includes transmitting the message over the first wired network when at least one destination of the message is located in the first security layer. The method further includes wirelessly transmitting the message for delivery to a second wireless node when at least one destination of the message is located in a second security layer. The second wireless node is associated with a second wired network, and the second wired network is associated with the second security layer. The first and second security layers may be associated with different security paradigms and/or different security domains. Also, the message could be associated with destinations in the first and second security layers.

  6. LANSCE personnel access control system

    SciTech Connect

    Sturrock, J.C.; Gallegos, F.R.; Hall, M.J.

    1997-01-01

    The Radiation Security System (RSS) at the Los Alamos Neutron Science Center (LANSCE) provides personnel protection from prompt radiation due to accelerated beam. The Personnel Access Control System (PACS) is a component of the RSS that is designed to prevent personnel access to areas where prompt radiation is a hazard. PACS was designed to replace several older personnel safety systems (PSS) with a single modem unified design. Lessons learned from the operation over the last 20 years were incorporated into a redundant sensor, single-point failure safe, fault tolerant, and tamper-resistant system that prevents access to the beam areas by controlling the access keys and beam stoppers. PACS uses a layered philosophy to the physical and electronic design. The most critical assemblies are battery backed up, relay logic circuits; less critical devices use Programmable Logic Controllers (PLCs) for timing functions and communications. Outside reviewers have reviewed the operational safety of the design. The design philosophy, lessons learned, hardware design, software design, operation, and limitations of the device are described.

  7. Mobile access control vestibule

    NASA Astrophysics Data System (ADS)

    DePoy, Jennifer M.

    1998-12-01

    The mobile access control vestibule (MACV) is an adaptation of techniques developed for mobile military command centers. The overall configuration of modules acts as an entry control/screening facility or transportable command center. The system would provide the following capabilities: (1) A key element for force protection, rapid deployment units sent to areas having no prepositioned equipment or where there has been a degradation of that equipment as a result of natural disasters or civil unrest. (2) A rapidly deployable security control center to upgrade the security at nonmilitary sites (e.g., diplomatic or humanitarian organizations). (3) Personnel screening, package screening, badge/identification card production for authorized personnel, centralized monitoring of deployed perimeter sensors, and centralized communications for law enforcement personnel. (4) Self-contained screening and threat detection systems, including explosives detection using the system developed by Sandia National Laboratories for the FAA. When coupled with transportable electric generators, the system is self-sufficient. The communication system for the MACV would be a combination of physically wired and wireless communication units that supports by ad hoc networking.

  8. Controlling Access to Suicide Means

    PubMed Central

    Sarchiapone, Marco; Mandelli, Laura; Iosue, Miriam; Andrisano, Costanza; Roy, Alec

    2011-01-01

    Background: Restricting access to common means of suicide, such as firearms, toxic gas, pesticides and other, has been shown to be effective in reducing rates of death in suicide. In the present review we aimed to summarize the empirical and clinical literature on controlling the access to means of suicide. Methods: This review made use of both MEDLINE, ISI Web of Science and the Cochrane library databases, identifying all English articles with the keywords “suicide means”, “suicide method”, “suicide prediction” or “suicide prevention” and other relevant keywords. Results: A number of factors may influence an individual’s decision regarding method in a suicide act, but there is substantial support that easy access influences the choice of method. In many countries, restrictions of access to common means of suicide has lead to lower overall suicide rates, particularly regarding suicide by firearms in USA, detoxification of domestic and motor vehicle gas in England and other countries, toxic pesticides in rural areas, barriers at jumping sites and hanging, by introducing “safe rooms” in prisons and hospitals. Moreover, decline in prescription of barbiturates and tricyclic antidepressants (TCAs), as well as limitation of drugs pack size for paracetamol and salicylate has reduced suicides by overdose, while increased prescription of SSRIs seems to have lowered suicidal rates. Conclusions: Restriction to means of suicide may be particularly effective in contexts where the method is popular, highly lethal, widely available, and/or not easily substituted by other similar methods. However, since there is some risk of means substitution, restriction of access should be implemented in conjunction with other suicide prevention strategies. PMID:22408588

  9. Vapor Control Layer Recommendations

    SciTech Connect

    2009-09-08

    This information sheet describes the level of vapor control required on the interior side of framed walls with typical fibrous cavity insulation (fibreglass, rockwool, or cellulose, based on DOE climate zone of construction.

  10. Boundary Layer Control on Airfoils.

    ERIC Educational Resources Information Center

    Gerhab, George; Eastlake, Charles

    1991-01-01

    A phenomena, boundary layer control (BLC), produced when visualizing the fluidlike flow of air is described. The use of BLC in modifying aerodynamic characteristics of airfoils, race cars, and boats is discussed. (KR)

  11. ACCESS: Detector Control and Performance

    NASA Astrophysics Data System (ADS)

    Morris, Matthew J.; Kaiser, M.; McCandliss, S. R.; Rauscher, B. J.; Kimble, R. A.; Kruk, J. W.; Wright, E. L.; Bohlin, R.; Kurucz, R. L.; Riess, A. G.; Pelton, R.; Deustua, S. E.; Dixon, W. V.; Sahnow, D. J.; Mott, D. B.; Wen, Y.; Benford, D. J.; Gardner, J. P.; Feldman, P. D.; Moos, H. W.; Lampton, M.; Perlmutter, S.; Woodgate, B. E.

    2014-01-01

    ACCESS, Absolute Color Calibration Experiment for Standard Stars, is a series of rocket-borne sub-orbital missions and ground-based experiments that will enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35 to 1.7 micron bandpass (companion poster, Kaiser et al.). The flight detector and detector spare have been selected and integrated with their electronics and flight mount. The controller electronics have been flight qualified. Vibration testing to launch loads and thermal vacuum testing of the detector, mount, and housing have been successfully performed. Further improvements to the flight controller housing have been made. A cryogenic ground test system has been built. Dark current and read noise tests have been performed, yielding results consistent with the initial characterization tests of the detector performed by Goddard Space Flight Center’s Detector Characterization Lab (DCL). Detector control software has been developed and implemented for ground testing. Performance and integration of the detector and controller with the flight software will be presented. NASA APRA sounding rocket grant NNX08AI65G supports this work.

  12. The Application of Layer Theory to Design: The Control Layer

    ERIC Educational Resources Information Center

    Gibbons, Andrew S.; Langton, Matthew B.

    2016-01-01

    A theory of design layers proposed by Gibbons ("An Architectural Approach to Instructional Design." Routledge, New York, 2014) asserts that each layer of an instructional design is related to a body of theory closely associated with the concerns of that particular layer. This study focuses on one layer, the control layer, examining…

  13. Role-based access control model for GIS

    NASA Astrophysics Data System (ADS)

    Pan, Yuqing; Sheng, Yehua; Zhou, Jieyu

    2007-06-01

    Access control of Geographical Information System (GIS) has more complex spatial constraints than the general MIS system, it makes the classic role-based access control model(RBAC) can't be used in GIS. To achieve an effective Access Control Model for GIS, an extension model of the RBAC is presented in the paper. Firstly, this paper introduce the three kinds spatial constraints that included layer constraints, region constraints and spatial object constraints; Then the paper expanded the basic RBAC model, added regional class, layers class and so on; Finally, the paper has given the system RABC control model as well as the realization method in view of GIS. An extension model of the RBAC is applicable to mobile computing, wireless access and system about location is concluded by analyzing.

  14. SAGA: A standardized access layer to heterogeneous Distributed Computing Infrastructure

    NASA Astrophysics Data System (ADS)

    Merzky, Andre; Weidner, Ole; Jha, Shantenu

    2015-09-01

    Distributed Computing Infrastructure is characterized by interfaces that are heterogeneous-syntactically and semantically. SAGA represents the most comprehensive community effort to date to address the heterogeneity by defining a simple, uniform access layer. In this paper, we describe the basic concepts underpinning its design and development. We also discuss RADICAL-SAGA which is the most widely used implementation of SAGA.

  15. Common Badging and Access Control System (CBACS)

    NASA Technical Reports Server (NTRS)

    Dischinger, Portia

    2005-01-01

    This slide presentation presents NASA's Common Badging and Access Control System. NASA began a Smart Card implementation in January 2004. Following site surveys, it was determined that NASA's badging and access control systems required upgrades to common infrastructure in order to provide flexibly, usability, and return on investment prior to a smart card implantation. Common Badging and Access Control System (CBACS) provides the common infrastructure from which FIPS-201 compliant processes, systems, and credentials can be developed and used.

  16. Boundary layer receptivity and control

    NASA Technical Reports Server (NTRS)

    Hill, D. C.

    1993-01-01

    Receptivity processes initiate natural instabilities in a boundary layer. The instabilities grow and eventually break down to turbulence. Consequently, receptivity questions are a critical element of the analysis of the transition process. Success in modeling the physics of receptivity processes thus has a direct bearing on technological issues of drag reduction. The means by which transitional flows can be controlled is also a major concern: questions of control are tied inevitably to those of receptivity. Adjoint systems provide a highly effective mathematical method for approaching many of the questions associated with both receptivity and control. The long term objective is to develop adjoint methods to handle increasingly complex receptivity questions, and to find systematic procedures for deducing effective control strategies. The most elementary receptivity problem is that in which a parallel boundary layer is forced by time-harmonic sources of various types. The characteristics of the response to such forcing form the building blocks for more complex receptivity mechanisms. The first objective of this year's research effort was to investigate how a parallel Blasius boundary layer responds to general direct forcing. Acoustic disturbances in the freestream can be scattered by flow non-uniformities to produce Tollmien-Schlichting waves. For example, scattering by surface roughness is known to provide an efficient receptivity path. The present effort is directed towards finding a solution by a simple adjoint analysis, because adjoint methods can be extended to more complex problems. In practice, flows are non-parallel and often three-dimensional. Compressibility may also be significant in some cases. Recent developments in the use of Parabolized Stability Equations (PSE) offer a promising possibility. By formulating and solving a set of adjoint parabolized equations, a method for mapping the efficiency with which external forcing excites the three

  17. Spatiotemporal access model based on reputation for the sensing layer of the IoT.

    PubMed

    Guo, Yunchuan; Yin, Lihua; Li, Chao; Qian, Junyan

    2014-01-01

    Access control is a key technology in providing security in the Internet of Things (IoT). The mainstream security approach proposed for the sensing layer of the IoT concentrates only on authentication while ignoring the more general models. Unreliable communications and resource constraints make the traditional access control techniques barely meet the requirements of the sensing layer of the IoT. In this paper, we propose a model that combines space and time with reputation to control access to the information within the sensing layer of the IoT. This model is called spatiotemporal access control based on reputation (STRAC). STRAC uses a lattice-based approach to decrease the size of policy bases. To solve the problem caused by unreliable communications, we propose both nondeterministic authorizations and stochastic authorizations. To more precisely manage the reputation of nodes, we propose two new mechanisms to update the reputation of nodes. These new approaches are the authority-based update mechanism (AUM) and the election-based update mechanism (EUM). We show how the model checker UPPAAL can be used to analyze the spatiotemporal access control model of an application. Finally, we also implement a prototype system to demonstrate the efficiency of our model.

  18. Spatiotemporal Access Model Based on Reputation for the Sensing Layer of the IoT

    PubMed Central

    Guo, Yunchuan; Yin, Lihua; Li, Chao

    2014-01-01

    Access control is a key technology in providing security in the Internet of Things (IoT). The mainstream security approach proposed for the sensing layer of the IoT concentrates only on authentication while ignoring the more general models. Unreliable communications and resource constraints make the traditional access control techniques barely meet the requirements of the sensing layer of the IoT. In this paper, we propose a model that combines space and time with reputation to control access to the information within the sensing layer of the IoT. This model is called spatiotemporal access control based on reputation (STRAC). STRAC uses a lattice-based approach to decrease the size of policy bases. To solve the problem caused by unreliable communications, we propose both nondeterministic authorizations and stochastic authorizations. To more precisely manage the reputation of nodes, we propose two new mechanisms to update the reputation of nodes. These new approaches are the authority-based update mechanism (AUM) and the election-based update mechanism (EUM). We show how the model checker UPPAAL can be used to analyze the spatiotemporal access control model of an application. Finally, we also implement a prototype system to demonstrate the efficiency of our model. PMID:25177731

  19. Spatiotemporal access model based on reputation for the sensing layer of the IoT.

    PubMed

    Guo, Yunchuan; Yin, Lihua; Li, Chao; Qian, Junyan

    2014-01-01

    Access control is a key technology in providing security in the Internet of Things (IoT). The mainstream security approach proposed for the sensing layer of the IoT concentrates only on authentication while ignoring the more general models. Unreliable communications and resource constraints make the traditional access control techniques barely meet the requirements of the sensing layer of the IoT. In this paper, we propose a model that combines space and time with reputation to control access to the information within the sensing layer of the IoT. This model is called spatiotemporal access control based on reputation (STRAC). STRAC uses a lattice-based approach to decrease the size of policy bases. To solve the problem caused by unreliable communications, we propose both nondeterministic authorizations and stochastic authorizations. To more precisely manage the reputation of nodes, we propose two new mechanisms to update the reputation of nodes. These new approaches are the authority-based update mechanism (AUM) and the election-based update mechanism (EUM). We show how the model checker UPPAAL can be used to analyze the spatiotemporal access control model of an application. Finally, we also implement a prototype system to demonstrate the efficiency of our model. PMID:25177731

  20. 47 CFR 95.645 - Control accessibility.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Control accessibility. 95.645 Section 95.645 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Technical Regulations Certification Requirements § 95.645 Control accessibility. (a) No...

  1. 47 CFR 95.645 - Control accessibility.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Control accessibility. 95.645 Section 95.645 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Technical Regulations Certification Requirements § 95.645 Control accessibility. (a) No...

  2. 47 CFR 95.645 - Control accessibility.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Control accessibility. 95.645 Section 95.645 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Technical Regulations Certification Requirements § 95.645 Control accessibility. (a) No...

  3. 47 CFR 95.645 - Control accessibility.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Control accessibility. 95.645 Section 95.645 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PERSONAL RADIO SERVICES Technical Regulations Certification Requirements § 95.645 Control accessibility. (a) No...

  4. Control of Separated Boundary Layers

    NASA Astrophysics Data System (ADS)

    Huang, Shao-Ching; Kim, John

    2003-11-01

    The control of separated boundary layers are numerically investigated. Two types of flow geometry are considered. The first case is flow separation on a flat plate caused by an imposed adverse pressure gradient. The second case is flow separation downstream of a curved leading edge. These cases represent laminar separation with turbulent reattachment with and without curvature effects. Open-loop control, with distributed surface blowing and suction as control input, is first applied to establish base-line cases. We then use a system identification approach to construct approximate system models for design of closed-loop control. The models are based on the input-output relationship obtained from numerical simulations. The linear quadratic Gaussian (LQG) control synthesis is applied to the models to produce feedback control laws. The distributed sensors and actuators are confined to the walls. The efficacy of the controllers are quantified by pressure distribution, separation bubble size and Reynolds stresses. Visualization of the controlled and uncontrolled flow fields will also be presented.

  5. Proximity Displays for Access Control

    ERIC Educational Resources Information Center

    Vaniea, Kami

    2012-01-01

    Managing access to shared digital information, such as photographs and documents. is difficult for end users who are accumulating an increasingly large and diverse collection of data that they want to share with others. Current policy-management solutions require a user to proactively seek out and open a separate policy-management interface when…

  6. An Accelerator Control Middle Layer Using MATLAB

    SciTech Connect

    Portmann, Gregory J.; Corbett, Jeff; Terebilo, Andrei

    2005-05-15

    Matlab is an interpretive programming language originally developed for convenient use with the LINPACK and EISPACK libraries. Matlab is appealing for accelerator physics because it is matrix-oriented, provides an active workspace for system variables, powerful graphics capabilities, built-in math libraries, and platform independence. A number of accelerator software toolboxes have been written in Matlab -- the Accelerator Toolbox (AT) for model-based machine simulations, LOCO for on-line model calibration, and Matlab Channel Access (MCA) to connect with EPICS. The function of the MATLAB ''MiddleLayer'' is to provide a scripting language for machine simulations and on-line control, including non-EPICS based control systems. The MiddleLayer has simplified and streamlined development of high-level applications including configuration control, energy ramp, orbit correction, photon beam steering, ID compensation, beam-based alignment, tune correction and response matrix measurement. The database-driven Middle Layer software is largely machine-independent and easy to port. Six accelerators presently use the software package with more scheduled to come on line soon.

  7. An Accelerator Control Middle Layer Using MATLAB

    SciTech Connect

    Portmann, Gregory J.; Corbett, Jeff; Terebilo, Andrei

    2005-03-15

    Matlab is a matrix manipulation language originally developed to be a convenient language for using the LINPACK and EISPACK libraries. What makes Matlab so appealing for accelerator physics is the combination of a matrix oriented programming language, an active workspace for system variables, powerful graphics capability, built-in math libraries, and platform independence. A number of software toolboxes for accelerators have been written in Matlab--the Accelerator Toolbox (AT) for machine simulations, LOCO for accelerator calibration, Matlab Channel Access Toolbox (MCA) for EPICS connections, and the Middle Layer. This paper will describe the ''middle layer'' software toolbox that resides between the high-level control applications and the low-level accelerator control system. This software was a collaborative effort between ALS (LBNL) and SPEAR3 (SSRL) but easily ports to other machines. Five accelerators presently use this software. The high-level Middle Layer functionality includes energy ramp, configuration control (save/restore), global orbit correction, local photon beam steering, insertion device compensation, beam-based alignment, tune correction, response matrix measurement, and script-based programs for machine physics studies.

  8. Formal Description of Trust-based Access Control

    NASA Astrophysics Data System (ADS)

    Xiaoning, Ma

    Different from traditional access control technologies, such as discretionary access control, mandatory access control, role-based access control, trust-based access control can solve the problem of uncertainty, risk and vulnerability coming from authorization. In this paper, strict definition and formal description of trust-based access control is defined.

  9. Access Control of Web and Java Based Applications

    NASA Technical Reports Server (NTRS)

    Tso, Kam S.; Pajevski, Michael J.; Johnson, Bryan

    2011-01-01

    Cyber security has gained national and international attention as a result of near continuous headlines from financial institutions, retail stores, government offices and universities reporting compromised systems and stolen data. Concerns continue to rise as threats of service interruption, and spreading of viruses become ever more prevalent and serious. Controlling access to application layer resources is a critical component in a layered security solution that includes encryption, firewalls, virtual private networks, antivirus, and intrusion detection. In this paper we discuss the development of an application-level access control solution, based on an open-source access manager augmented with custom software components, to provide protection to both Web-based and Java-based client and server applications.

  10. Access Control of Web- and Java-Based Applications

    NASA Technical Reports Server (NTRS)

    Tso, Kam S.; Pajevski, Michael J.

    2013-01-01

    Cybersecurity has become a great concern as threats of service interruption, unauthorized access, stealing and altering of information, and spreading of viruses have become more prevalent and serious. Application layer access control of applications is a critical component in the overall security solution that also includes encryption, firewalls, virtual private networks, antivirus, and intrusion detection. An access control solution, based on an open-source access manager augmented with custom software components, was developed to provide protection to both Web-based and Javabased client and server applications. The DISA Security Service (DISA-SS) provides common access control capabilities for AMMOS software applications through a set of application programming interfaces (APIs) and network- accessible security services for authentication, single sign-on, authorization checking, and authorization policy management. The OpenAM access management technology designed for Web applications can be extended to meet the needs of Java thick clients and stand alone servers that are commonly used in the JPL AMMOS environment. The DISA-SS reusable components have greatly reduced the effort for each AMMOS subsystem to develop its own access control strategy. The novelty of this work is that it leverages an open-source access management product that was designed for Webbased applications to provide access control for Java thick clients and Java standalone servers. Thick clients and standalone servers are still commonly used in businesses and government, especially for applications that require rich graphical user interfaces and high-performance visualization that cannot be met by thin clients running on Web browsers

  11. A physical layer perspective on access network sharing

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Thomas

    2015-12-01

    Unlike in copper or wireless networks, there is no sharing of resources in fiber access networks yet, other than bit stream access or cable sharing, in which the fibers of a cable are let to one or multiple operators. Sharing optical resources on a single fiber among multiple operators or different services has not yet been applied. While this would allow for a better exploitation of installed infrastructures, there are operational issues which still need to be resolved, before this sharing model can be implemented in networks. Operating multiple optical systems and services over a common fiber plant, autonomously and independently from each other, can result in mutual distortions on the physical layer. These distortions will degrade the performance of the involved systems, unless precautions are taken in the infrastructure hardware to eliminate or to reduce them to an acceptable level. Moreover, the infrastructure needs to be designed such as to support different system technologies and to ensure a guaranteed quality of the end-to-end connections. In this paper, suitable means are proposed to be introduced in fiber access infrastructures that will allow for shared utilization of the fibers while safeguarding the operational needs and business interests of the involved parties.

  12. Access Control Management for SCADA Systems

    NASA Astrophysics Data System (ADS)

    Hong, Seng-Phil; Ahn, Gail-Joon; Xu, Wenjuan

    The information technology revolution has transformed all aspects of our society including critical infrastructures and led a significant shift from their old and disparate business models based on proprietary and legacy environments to more open and consolidated ones. Supervisory Control and Data Acquisition (SCADA) systems have been widely used not only for industrial processes but also for some experimental facilities. Due to the nature of open environments, managing SCADA systems should meet various security requirements since system administrators need to deal with a large number of entities and functions involved in critical infrastructures. In this paper, we identify necessary access control requirements in SCADA systems and articulate access control policies for the simulated SCADA systems. We also attempt to analyze and realize those requirements and policies in the context of role-based access control that is suitable for simplifying administrative tasks in large scale enterprises.

  13. 10 CFR 36.23 - Access control.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Access control. 36.23 Section 36.23 Energy NUCLEAR... activation of the control. (g) Each entrance to the radiation room of a panoramic irradiator and each... required by 10 CFR 20.1902. Radiation postings for panoramic irradiators must comply with the...

  14. 10 CFR 36.23 - Access control.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Access control. 36.23 Section 36.23 Energy NUCLEAR... activation of the control. (g) Each entrance to the radiation room of a panoramic irradiator and each... required by 10 CFR 20.1902. Radiation postings for panoramic irradiators must comply with the...

  15. 10 CFR 36.23 - Access control.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Access control. 36.23 Section 36.23 Energy NUCLEAR... activation of the control. (g) Each entrance to the radiation room of a panoramic irradiator and each... required by 10 CFR 20.1902. Radiation postings for panoramic irradiators must comply with the...

  16. 10 CFR 36.23 - Access control.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Access control. 36.23 Section 36.23 Energy NUCLEAR... activation of the control. (g) Each entrance to the radiation room of a panoramic irradiator and each... required by 10 CFR 20.1902. Radiation postings for panoramic irradiators must comply with the...

  17. 10 CFR 36.23 - Access control.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Access control. 36.23 Section 36.23 Energy NUCLEAR... activation of the control. (g) Each entrance to the radiation room of a panoramic irradiator and each... required by 10 CFR 20.1902. Radiation postings for panoramic irradiators must comply with the...

  18. The Ins and Outs of Access Control.

    ERIC Educational Resources Information Center

    Longworth, David

    1999-01-01

    Presents basic considerations when school districts plan to acquire an access-control system for their education facilities. Topics cover cards and readers, controllers, software, automation, card technology, expandability, price, specification of needs beyond the canned specifications already supplied, and proper usage training to cardholders.…

  19. The linked medical data access control framework.

    PubMed

    Kamateri, Eleni; Kalampokis, Evangelos; Tambouris, Efthimios; Tarabanis, Konstantinos

    2014-08-01

    The integration of medical data coming from multiple sources is important in clinical research. Amongst others, it enables the discovery of appropriate subjects in patient-oriented research and the identification of innovative results in epidemiological studies. At the same time, the integration of medical data faces significant ethical and legal challenges that impose access constraints. Some of these issues can be addressed by making available aggregated instead of raw record-level data. In many cases however, there is still a need for controlling access even to the resulting aggregated data, e.g., due to data provider's policies. In this paper we present the Linked Medical Data Access Control (LiMDAC) framework that capitalizes on Linked Data technologies to enable controlling access to medical data across distributed sources with diverse access constraints. The LiMDAC framework consists of three Linked Data models, namely the LiMDAC metadata model, the LiMDAC user profile model, and the LiMDAC access policy model. It also includes an architecture that exploits these models. Based on the framework, a proof-of-concept platform is developed and its performance and functionality are evaluated by employing two usage scenarios.

  20. Implementing context and team based access control in healthcare intranets.

    PubMed

    Georgiadis, Christos K; Mavridis, Ioannis K; Nikolakopoulou, Georgia; Pangalos, George I

    2002-09-01

    The establishment of an efficient access control system in healthcare intranets is a critical security issue directly related to the protection of patients' privacy. Our C-TMAC (Context and Team-based Access Control) model is an active security access control model that layers dynamic access control concepts on top of RBAC (Role-based) and TMAC (Team-based) access control models. It also extends them in the sense that contextual information concerning collaborative activities is associated with teams of users and user permissions are dynamically filtered during runtime. These features of C-TMAC meet the specific security requirements of healthcare applications. In this paper, an experimental implementation of the C-TMAC model is described. More specifically, we present the operational architecture of the system that is used to implement C-TMAC security components in a healthcare intranet. Based on the technological platform of an Oracle Data Base Management System and Application Server, the application logic is coded with stored PL/SQL procedures that include Dynamic SQL routines for runtime value binding purposes. The resulting active security system adapts to current need-to-know requirements of users during runtime and provides fine-grained permission granularity. Apart from identity certificates for authentication, it uses attribute certificates for communicating critical security metadata, such as role membership and team participation of users.

  1. Access control mechanisms for distributed healthcare environments.

    PubMed

    Sergl-Pommerening, Marita

    2004-01-01

    Today's IT-infrastructure provides more and more possibilities to share electronic patient data across several healthcare organizations and hospital departments. A strong requirement is sufficient data protection and security measures complying with the medical confidentiality and the data protection laws of each state or country like the European directive on data protection or the U.S. HIPAA privacy rule. In essence, the access control mechanisms and authorization structures of information systems must be able to realize the Need-To-Access principle. This principle can be understood as a set of context-sensitive access rules, regarding the patient's path across the organizations. The access control mechanisms of today's health information systems do not sufficiently satisfy this requirement, because information about participation of persons or organizations is not available within each system in a distributed environment. This problem could be solved by appropriate security services. The CORBA healthcare domain standard contains such a service for obtaining authorization decisions and administrating access decision policies (RAD). At the university hospital of Mainz we have developed an access control system (MACS), which includes the main functionality of the RAD specification and the access control logic that is needed for such a service. The basic design principles of our approach are role-based authorization, user rights with static and dynamic authorization data, context rules and the separation of three cooperating servers that provide up-to-date knowledge about users, roles and responsibilities. This paper introduces the design principles and the system design and critically evaluates the concepts based on practical experience.

  2. Layer Control of WSe2 via Selective Surface Layer Oxidation.

    PubMed

    Li, Zhen; Yang, Sisi; Dhall, Rohan; Kosmowska, Ewa; Shi, Haotian; Chatzakis, Ioannis; Cronin, Stephen B

    2016-07-26

    We report Raman and photoluminescence spectra of mono- and few-layer WSe2 and MoSe2 taken before and after exposure to a remote oxygen plasma. For bilayer and trilayer WSe2, we observe an increase in the photoluminescence intensity and a blue shift of the photoluminescence peak positions after oxygen plasma treatment. The photoluminescence spectra of trilayer WSe2 exhibit features of a bilayer after oxygen plasma treatment. Bilayer WSe2 exhibits features of a monolayer, and the photoluminescence of monolayer WSe2 is completely absent after the oxygen plasma treatment. These changes are observed consistently in more than 20 flakes. The mechanism of the changes observed in the photoluminescence spectra of WSe2 is due to the selective oxidation of the topmost layer. As a result, N-layer WSe2 is reduced to N-1 layers. Raman spectra and AFM images taken from the WSe2 flakes before and after the oxygen treatment corroborate these findings. Because of the low kinetic energy of the oxygen radicals in the remote oxygen plasma, the oxidation is self-limiting. By varying the process duration from 1 to 10 min, we confirmed that the oxidation will only affect the topmost layer of the WSe2 flakes. X-ray photoelectron spectroscopy shows that the surface layer WOx of the sample can be removed by a quick dip in KOH solution. Therefore, this technique provides a promising way of controlling the thickness of WSe2 layer by layer. PMID:27391161

  3. Network Access Control List Situation Awareness

    ERIC Educational Resources Information Center

    Reifers, Andrew

    2010-01-01

    Network security is a large and complex problem being addressed by multiple communities. Nevertheless, current theories in networking security appear to overestimate network administrators' ability to understand network access control lists (NACLs), providing few context specific user analyses. Consequently, the current research generally seems to…

  4. Atom-Role-Based Access Control Model

    NASA Astrophysics Data System (ADS)

    Cai, Weihong; Huang, Richeng; Hou, Xiaoli; Wei, Gang; Xiao, Shui; Chen, Yindong

    Role-based access control (RBAC) model has been widely recognized as an efficient access control model and becomes a hot research topic of information security at present. However, in the large-scale enterprise application environments, the traditional RBAC model based on the role hierarchy has the following deficiencies: Firstly, it is unable to reflect the role relationships in complicated cases effectively, which does not accord with practical applications. Secondly, the senior role unconditionally inherits all permissions of the junior role, thus if a user is under the supervisor role, he may accumulate all permissions, and this easily causes the abuse of permission and violates the least privilege principle, which is one of the main security principles. To deal with these problems, we, after analyzing permission types and role relationships, proposed the concept of atom role and built an atom-role-based access control model, called ATRBAC, by dividing the permission set of each regular role based on inheritance path relationships. Through the application-specific analysis, this model can well meet the access control requirements.

  5. Speed control system for an access gate

    SciTech Connect

    Bzorgi, Fariborz M.

    2012-03-20

    An access control apparatus for an access gate. The access gate typically has a rotator that is configured to rotate around a rotator axis at a first variable speed in a forward direction. The access control apparatus may include a transmission that typically has an input element that is operatively connected to the rotator. The input element is generally configured to rotate at an input speed that is proportional to the first variable speed. The transmission typically also has an output element that has an output speed that is higher than the input speed. The input element and the output element may rotate around a common transmission axis. A retardation mechanism may be employed. The retardation mechanism is typically configured to rotate around a retardation mechanism axis. Generally the retardation mechanism is operatively connected to the output element of the transmission and is configured to retard motion of the access gate in the forward direction when the first variable speed is above a control-limit speed. In many embodiments the transmission axis and the retardation mechanism axis are substantially co-axial. Some embodiments include a freewheel/catch mechanism that has an input connection that is operatively connected to the rotator. The input connection may be configured to engage an output connection when the rotator is rotated at the first variable speed in a forward direction and configured for substantially unrestricted rotation when the rotator is rotated in a reverse direction opposite the forward direction. The input element of the transmission is typically operatively connected to the output connection of the freewheel/catch mechanism.

  6. Common Badging and Access Control System (CBACS)

    NASA Technical Reports Server (NTRS)

    Baldridge, Tim

    2005-01-01

    The goals of the project are: Achieve high business value through a common badging and access control system that integrates with smart cards. Provide physical (versus logical) deployment of smart cards initially. Provides a common consistent and reliable environment into which to release the smart card. Gives opportunity to develop agency-wide consistent processes, practices and policies. Enables enterprise data capture and management. Promotes data validation prior to SC issuance.

  7. Boundary-layer control for drag reduction

    NASA Technical Reports Server (NTRS)

    Harvey, William D.

    1988-01-01

    Although the number of possible applications of boundary-layer control is large, a discussion is given only of those that have received the most attention recently at NASA Langley Research Center to improve airfoil drag characteristics. This research concerns stabilizing the laminar boundary layer through geometric shaping (natural laminar flow, NLF) and active control involving the removal of a portion of the laminar boundary layer (laminar flow control, LFC) either through discrete slots or a perforated surface. At low Reynolds numbers, a combination of shaping and forced transition has been used to achieve the desired run of laminar flow and control of laminar separation. In the design of both natural laminar flow and laminar flow control airfoils and wings, boundary layer stability codes play an important role. A discussion of some recent stability calculations using both incompressible and compressible codes is given.

  8. External access to ALICE controls conditions data

    NASA Astrophysics Data System (ADS)

    Jadlovský, J.; Jadlovská, A.; Sarnovský, J.; Jajčišin, Š.; Čopík, M.; Jadlovská, S.; Papcun, P.; Bielek, R.; Čerkala, J.; Kopčík, M.; Chochula, P.; Augustinus, A.

    2014-06-01

    ALICE Controls data produced by commercial SCADA system WINCCOA is stored in ORACLE database on the private experiment network. The SCADA system allows for basic access and processing of the historical data. More advanced analysis requires tools like ROOT and needs therefore a separate access method to the archives. The present scenario expects that detector experts create simple WINCCOA scripts, which retrieves and stores data in a form usable for further studies. This relatively simple procedure generates a lot of administrative overhead - users have to request the data, experts needed to run the script, the results have to be exported outside of the experiment network. The new mechanism profits from database replica, which is running on the CERN campus network. Access to this database is not restricted and there is no risk of generating a heavy load affecting the operation of the experiment. The developed tools presented in this paper allow for access to this data. The users can use web-based tools to generate the requests, consisting of the data identifiers and period of time of interest. The administrators maintain full control over the data - an authorization and authentication mechanism helps to assign privileges to selected users and restrict access to certain groups of data. Advanced caching mechanism allows the user to profit from the presence of already processed data sets. This feature significantly reduces the time required for debugging as the retrieval of raw data can last tens of minutes. A highly configurable client allows for information retrieval bypassing the interactive interface. This method is for example used by ALICE Offline to extract operational conditions after a run is completed. Last but not least, the software can be easily adopted to any underlying database structure and is therefore not limited to WINCCOA.

  9. Access control and confidentiality in radiology

    NASA Astrophysics Data System (ADS)

    Noumeir, Rita; Chafik, Adil

    2005-04-01

    A medical record contains a large amount of data about the patient such as height, weight and blood pressure. It also contains sensitive information such as fertility, abortion, psychiatric data, sexually transmitted diseases and diagnostic results. Access to this information must be carefully controlled. Information technology has greatly improved patient care. The recent extensive deployment of digital medical images made diagnostic images promptly available to healthcare decision makers, regardless of their geographic location. Medical images are digitally archived, transferred on telecommunication networks, and visualized on computer screens. However, with the widespread use of computing and communication technologies in healthcare, the issue of data security has become increasingly important. Most of the work until now has focused on the security of data communication to ensure its integrity, authentication, confidentiality and user accountability. The mechanisms that have been proposed to achieve the security of data communication are not specific to healthcare. Data integrity can be achieved with data signature. Data authentication can be achieved with certificate exchange. Data confidentiality can be achieved with encryption. User accountability can be achieved with audits. Although these mechanisms are essential to ensure data security during its transfer on the network, access control is needed in order to ensure data confidentiality and privacy within the information system application. In this paper, we present and discuss an access control mechanism that takes into account the notion of a care process. Radiology information is categorized and a model to enforce data privacy is proposed.

  10. Type-Based Access Control in Data-Centric Systems

    NASA Astrophysics Data System (ADS)

    Caires, Luís; Pérez, Jorge A.; Seco, João Costa; Vieira, Hugo Torres; Ferrão, Lúcio

    Data-centric multi-user systems, such as web applications, require flexible yet fine-grained data security mechanisms. Such mechanisms are usually enforced by a specially crafted security layer, which adds extra complexity and often leads to error prone coding, easily causing severe security breaches. In this paper, we introduce a programming language approach for enforcing access control policies to data in data-centric programs by static typing. Our development is based on the general concept of refinement type, but extended so as to address realistic and challenging scenarios of permission-based data security, in which policies dynamically depend on the database state, and flexible combinations of column- and row-level protection of data are necessary. We state and prove soundness and safety of our type system, stating that well-typed programs never break the declared data access control policies.

  11. Cyclone separator having boundary layer turbulence control

    DOEpatents

    Krishna, Coimbatore R.; Milau, Julius S.

    1985-01-01

    A cyclone separator including boundary layer turbulence control that is operable to prevent undue build-up of particulate material at selected critical areas on the separator walls, by selectively varying the fluid pressure at those areas to maintain the momentum of the vortex, thereby preventing particulate material from inducing turbulence in the boundary layer of the vortical fluid flow through the separator.

  12. Collaborative Access Control For Critical Infrastructures

    NASA Astrophysics Data System (ADS)

    Baina, Amine; El Kalam, Anas Abou; Deswarte, Yves; Kaaniche, Mohamed

    A critical infrastructure (CI) can fail with various degrees of severity due to physical and logical vulnerabilities. Since many interdependencies exist between CIs, failures can have dramatic consequences on the entire infrastructure. This paper focuses on threats that affect information and communication systems that constitute the critical information infrastructure (CII). A new collaborative access control framework called PolyOrBAC is proposed to address security problems that are specific to CIIs. The framework offers each organization participating in a CII the ability to collaborate with other organizations while maintaining control of its resources and internal security policy. The approach is demonstrated on a practical scenario involving the electrical power grid.

  13. Controlled Layer-by-Layer Etching of MoS₂.

    PubMed

    Lin, TaiZhe; Kang, BaoTao; Jeon, MinHwan; Huffman, Craig; Jeon, JeaHoo; Lee, SungJoo; Han, Wei; Lee, JinYong; Lee, SeHan; Yeom, GeunYoung; Kim, KyongNam

    2015-07-29

    Two-dimensional (2D) metal dichalcogenides like molybdenum disulfide (MoS2) may provide a pathway to high-mobility channel materials that are needed for beyond-complementary metal-oxide-semiconductor (CMOS) devices. Controlling the thickness of these materials at the atomic level will be a key factor in the future development of MoS2 devices. In this study, we propose a layer-by-layer removal of MoS2 using the atomic layer etching (ALET) that is composed of the cyclic processing of chlorine (Cl)-radical adsorption and argon (Ar)(+) ion-beam desorption. MoS2 etching was not observed with only the Cl-radical adsorption or low-energy (<20 eV) Ar(+) ion-beam desorption steps; however, the use of sequential etching that is composed of the Cl-radical adsorption step and a subsequent Ar(+) ion-beam desorption step resulted in the complete etching of one monolayer of MoS2. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) indicated the removal of one monolayer of MoS2 with each ALET cycle; therefore, the number of MoS2 layers could be precisely controlled by using this cyclical etch method. In addition, no noticeable damage or etch residue was observed on the exposed MoS2.

  14. 14 CFR 420.53 - Control of public access.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Control of public access. 420.53 Section....53 Control of public access. (a) A licensee shall prevent unauthorized access to the launch site, and unauthorized, unescorted access to explosive hazard facilities or other hazard areas not otherwise...

  15. Cardea: Dynamic Access Control in Distributed Systems

    NASA Technical Reports Server (NTRS)

    Lepro, Rebekah

    2004-01-01

    Modern authorization systems span domains of administration, rely on many different authentication sources, and manage complex attributes as part of the authorization process. This . paper presents Cardea, a distributed system that facilitates dynamic access control, as a valuable piece of an inter-operable authorization framework. First, the authorization model employed in Cardea and its functionality goals are examined. Next, critical features of the system architecture and its handling of the authorization process are then examined. Then the S A M L and XACML standards, as incorporated into the system, are analyzed. Finally, the future directions of this project are outlined and connection points with general components of an authorization system are highlighted.

  16. Boundary-Layer-Ingesting Inlet Flow Control

    NASA Technical Reports Server (NTRS)

    Owens, Lewis R.; Allan, Brian G.; Gorton, Susan A.

    2008-01-01

    An experimental study was conducted to provide the first demonstration of an active flow control system for a flush-mounted inlet with significant boundary-layer-ingestion in transonic flow conditions. The effectiveness of the flow control in reducing the circumferential distortion at the engine fan-face location was assessed using a 2.5%-scale model of a boundary-layer-ingesting offset diffusing inlet. The inlet was flush mounted to the tunnel wall and ingested a large boundary layer with a boundary-layer-to-inlet height ratio of 35%. Different jet distribution patterns and jet mass flow rates were used in the inlet to control distortion. A vane configuration was also tested. Finally a hybrid vane/jet configuration was tested leveraging strengths of both types of devices. Measurements were made of the onset boundary layer, the duct surface static pressures, and the mass flow rates through the duct and the flow control actuators. The distortion and pressure recovery were measured at the aerodynamic interface plane. The data show that control jets and vanes reduce circumferential distortion to acceptable levels. The point-design vane configuration produced higher distortion levels at off-design settings. The hybrid vane/jet flow control configuration reduced the off-design distortion levels to acceptable ones and used less than 0.5% of the inlet mass flow to supply the jets.

  17. Adaptive MAC-layer protocol for multiservice digital access via tree and branch communication networks

    NASA Astrophysics Data System (ADS)

    Kotikalapudi, Sriram; Li, Chia-Chang; Magill, Peter D.; Whitaker, Norman A.; Dail, James E.; Dajer, Miguel A.; Siller, Curtis A., Jr.

    1995-11-01

    Described here is an adaptive MAC-layer protocol that supports multiservice (STM and ATM) applications in the context of subscriber access to tree and branch (e.g., fiber-coaxial cable) networks. The protocol adapts to changing demands for a mix of circuit and cell mode applications, and efficiently allocates upstream and downstream bandwidth to a variety of bursty and isochronous traffic sources. In the case of a hybrid fiber-coaxial (HFC) network the protocol resides in customer premises equipment and a common head-end controller. A medium-access control (MAC) processor provides for dividing the time domain for a given digital bitstream into successive frames, each with multiple STM and ATM time slots. Within the STM region of a frame, variable length time slots are allocated to calls (e.g., telephony, video telephony) requiring different amounts of bandwidth. A contention access signaling channel is also provided in this region for call control and set-up requests. Within the ATM region fixed-length time slots accommodate one individual ATM cell. These ATM time slots may be reserved for a user for the duration of a call or burst of successive ATM cells, or shared via a contention process. At least one contention time slot is available for signaling messages related to ATM call control and set-up requests. Further, the fixed-length ATM time slots may be reserved by a user for the duration of a call, or shared through a contention process. This paper describes the MAC-layer protocol, its relation to circuit- and ATM- amenable applications, and its performance with respect to signaling throughput and latency, and bandwidth efficiency for several service scenarios.

  18. Situation-Based Access Control: privacy management via modeling of patient data access scenarios.

    PubMed

    Peleg, Mor; Beimel, Dizza; Dori, Dov; Denekamp, Yaron

    2008-12-01

    Access control is a central problem in privacy management. A common practice in controlling access to sensitive data, such as electronic health records (EHRs), is Role-Based Access Control (RBAC). RBAC is limited as it does not account for the circumstances under which access to sensitive data is requested. Following a qualitative study that elicited access scenarios, we used Object-Process Methodology to structure the scenarios and conceive a Situation-Based Access Control (SitBAC) model. SitBAC is a conceptual model, which defines scenarios where patient's data access is permitted or denied. The main concept underlying this model is the Situation Schema, which is a pattern consisting of the entities Data-Requestor, Patient, EHR, Access Task, Legal-Authorization, and Response, along with their properties and relations. The various data access scenarios are expressed via Situation Instances. While we focus on the medical domain, the model is generic and can be adapted to other domains.

  19. Concurrency and Time in Role-Based Access Control

    NASA Astrophysics Data System (ADS)

    Chiang, Chia-Chu; Bayrak, Coskun

    Role-based access control (RBAC) has been proposed as an alternative solution for expressing access control policies. The generalized temporal RBAC (GTRBAC) extends RBAC by adding time in order to support timed based access control policies. However, GTRBAC does not address certain issues of concurrency such as, synchronization. We propose an approach to the expressions of time and concurrency in RBAC based on timed Petri nets. A formal verification method for access control policies is also proposed.

  20. Application-Defined Decentralized Access Control.

    PubMed

    Xu, Yuanzhong; Dunn, Alan M; Hofmann, Owen S; Lee, Michael Z; Mehdi, Syed Akbar; Witchel, Emmett

    2014-01-01

    DCAC is a practical OS-level access control system that supports application-defined principals. It allows normal users to perform administrative operations within their privilege, enabling isolation and privilege separation for applications. It does not require centralized policy specification or management, giving applications freedom to manage their principals while the policies are still enforced by the OS. DCAC uses hierarchically-named attributes as a generic framework for user-defined policies such as groups defined by normal users. For both local and networked file systems, its execution time overhead is between 0%-9% on file system microbenchmarks, and under 1% on applications. This paper shows the design and implementation of DCAC, as well as several real-world use cases, including sandboxing applications, enforcing server applications' security policies, supporting NFS, and authenticating user-defined sub-principals in SSH, all with minimal code changes.

  1. Application-Defined Decentralized Access Control

    PubMed Central

    Xu, Yuanzhong; Dunn, Alan M.; Hofmann, Owen S.; Lee, Michael Z.; Mehdi, Syed Akbar; Witchel, Emmett

    2014-01-01

    DCAC is a practical OS-level access control system that supports application-defined principals. It allows normal users to perform administrative operations within their privilege, enabling isolation and privilege separation for applications. It does not require centralized policy specification or management, giving applications freedom to manage their principals while the policies are still enforced by the OS. DCAC uses hierarchically-named attributes as a generic framework for user-defined policies such as groups defined by normal users. For both local and networked file systems, its execution time overhead is between 0%–9% on file system microbenchmarks, and under 1% on applications. This paper shows the design and implementation of DCAC, as well as several real-world use cases, including sandboxing applications, enforcing server applications’ security policies, supporting NFS, and authenticating user-defined sub-principals in SSH, all with minimal code changes. PMID:25426493

  2. Context-Based E-Health System Access Control Mechanism

    NASA Astrophysics Data System (ADS)

    Al-Neyadi, Fahed; Abawajy, Jemal H.

    E-Health systems logically demand a sufficiently fine-grained authorization policy for access control. The access to medical information should not be just role-based but should also include the contextual condition of the role to access data. In this paper, we present a mechanism to extend the standard role-based access control to incorporate contextual information for making access control decisions in e-health application. We present an architecture consisting of authorisation and context infrastructure that work cooperatively to grant access rights based on context-aware authorization policies and context information.

  3. Modeling mandatory access control in role-based security systems

    SciTech Connect

    Nyanchama, M.; Osborn, S.

    1996-12-31

    This paper discusses the realization of mandatory access control in role-based protection systems. Starting from the basic definitions of roles, their application in security and the basics of the concept of mandatory access control, we develop a scheme of role-based protection that realizes mandatory access control. The basis of this formulation develops from the recognition that roles can be seen as facilitating access to some given information context. By handling each of the role contexts as independent security levels of information, we simulate mandatory access by imposing the requirements of mandatory access control. Among the key considerations, we propose a means of taming Trojan horses by imposing acyclic information flow among contexts in role-based protection systems. The acyclic information flows and suitable access rules incorporate secrecy which is an essential component of mandatory access control.

  4. Boundary layer control device for duct silencers

    NASA Technical Reports Server (NTRS)

    Schmitz, Fredric H. (Inventor); Soderman, Paul T. (Inventor)

    1993-01-01

    A boundary layer control device includes a porous cover plate, an acoustic absorber disposed under the porous cover plate, and a porous flow resistive membrane interposed between the porous cover plate and the acoustic absorber. The porous flow resistive membrane has a flow resistance low enough to permit sound to enter the acoustic absorber and high enough to damp unsteady flow oscillations.

  5. 14 CFR 420.53 - Control of public access.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Control of public access. 420.53 Section 420.53 Aeronautics and Space COMMERCIAL SPACE TRANSPORTATION, FEDERAL AVIATION ADMINISTRATION....53 Control of public access. (a) A licensee shall prevent unauthorized access to the launch site,...

  6. Emergency access for online personally controlled health records system.

    PubMed

    Zhang, Yuan; Dhileepan, Sunethra; Schmidt, Matthew; Zhong, Sheng

    2012-09-01

    A personally controlled health records (PCHR) system allows a patient user to share his/her health records with trusted physicians by manually granting them the access privilege to his/her online records. However, it presents the problem of emergency access in situations where the user is physically unable to grant the access and the access is required by an Emergency Room (ER) physician who does not have the privilege at that moment. To deal with such a problem, we introduce an online polling system to provide the emergency access control to PCHR systems. For each emergency access request, the access privilege is controlled according to the combined opinions of the patient's preset emergency contacts and other online registered physicians. Because our system is based on the demographic number of the physician community nationwide, it provides a stable emergency access control at all times.

  7. Fixed-rate layered multicast congestion control

    NASA Astrophysics Data System (ADS)

    Bing, Zhang; Bing, Yuan; Zengji, Liu

    2006-10-01

    A new fixed-rate layered multicast congestion control algorithm called FLMCC is proposed. The sender of a multicast session transmits data packets at a fixed rate on each layer, while receivers each obtain different throughput by cumulatively subscribing to deferent number of layers based on their expected rates. In order to provide TCP-friendliness and estimate the expected rate accurately, a window-based mechanism implemented at receivers is presented. To achieve this, each receiver maintains a congestion window, adjusts it based on the GAIMD algorithm, and from the congestion window an expected rate is calculated. To measure RTT, a new method is presented which combines an accurate measurement with a rough estimation. A feedback suppression based on a random timer mechanism is given to avoid feedback implosion in the accurate measurement. The protocol is simple in its implementation. Simulations indicate that FLMCC shows good TCP-friendliness, responsiveness as well as intra-protocol fairness, and provides high link utilization.

  8. Thin Layer Samples Controlled by Dynamic Electrochemistry.

    PubMed

    Cuartero, Maria; Crespo, Gastón A; Bakker, Eric

    2015-01-01

    We summarize here recent advancements on thin layer samples controlled by dynamic electrochemistry techniques for determining different ions that include potassium, calcium, protamine, nitrate, nitrite and halides in diverse environmental and clinical samples. Generally, a thin layer liquid (less than 100 μm in thickness) is confined between a working electrode and an ion-selective membrane. Once an external electrical perturbation (i.e. constant potential) is applied to the system, an exhaustive ion transfer process is imposed in the entire thin layer solution. As a result, the observed charge (integration of the current decay) is proportional to the depleted ion concentration. Other electrochemical protocols such as linear sweep voltammetry were also explored aiming at the discrimination of several ions presented in the thin layer. One of the most attractive examples involves the detection of a mixture of three halides (iodide, bromide and chloride), which can be well resolved at moderated scan rates (10 mV.s(-1)). Paper-based coulometric sensing on thin layers defined by cellulose papers are being developed in view of translating these new concepts into a reliable and low cost sensing platform.

  9. Thin Layer Samples Controlled by Dynamic Electrochemistry.

    PubMed

    Cuartero, Maria; Crespo, Gastón A; Bakker, Eric

    2015-01-01

    We summarize here recent advancements on thin layer samples controlled by dynamic electrochemistry techniques for determining different ions that include potassium, calcium, protamine, nitrate, nitrite and halides in diverse environmental and clinical samples. Generally, a thin layer liquid (less than 100 μm in thickness) is confined between a working electrode and an ion-selective membrane. Once an external electrical perturbation (i.e. constant potential) is applied to the system, an exhaustive ion transfer process is imposed in the entire thin layer solution. As a result, the observed charge (integration of the current decay) is proportional to the depleted ion concentration. Other electrochemical protocols such as linear sweep voltammetry were also explored aiming at the discrimination of several ions presented in the thin layer. One of the most attractive examples involves the detection of a mixture of three halides (iodide, bromide and chloride), which can be well resolved at moderated scan rates (10 mV.s(-1)). Paper-based coulometric sensing on thin layers defined by cellulose papers are being developed in view of translating these new concepts into a reliable and low cost sensing platform. PMID:26668939

  10. Boundary-Layer-Ingesting Inlet Flow Control

    NASA Technical Reports Server (NTRS)

    Owens, Lewis R.; Allan, Brian G.; Gorton, Susan A.

    2006-01-01

    This paper gives an overview of a research study conducted in support of the small-scale demonstration of an active flow control system for a boundary-layer-ingesting (BLI) inlet. The effectiveness of active flow control in reducing engine inlet circumferential distortion was assessed using a 2.5% scale model of a 35% boundary-layer-ingesting flush-mounted, offset, diffusing inlet. This experiment was conducted in the NASA Langley 0.3-meter Transonic Cryogenic Tunnel at flight Mach numbers with a model inlet specifically designed for this type of testing. High mass flow actuators controlled the flow through distributed control jets providing the active flow control. A vortex generator point design configuration was also tested for comparison purposes and to provide a means to examine a hybrid vortex generator and control jets configuration. Measurements were made of the onset boundary layer, the duct surface static pressures, and the mass flow through the duct and the actuators. The distortion and pressure recovery were determined by 40 total pressure measurements on 8 rake arms each separated by 45 degrees and were located at the aerodynamic interface plane. The test matrix was limited to a maximum free-stream Mach number of 0.85 with scaled mass flows through the inlet for that condition. The data show that the flow control jets alone can reduce circumferential distortion (DPCPavg) from 0.055 to about 0.015 using about 2.5% of inlet mass flow. The vortex generators also reduced the circumferential distortion from 0.055 to 0.010 near the inlet mass flow design point. Lower inlet mass flow settings with the vortex generator configuration produced higher distortion levels that were reduced to acceptable levels using a hybrid vortex generator/control jets configuration that required less than 1% of the inlet mass flow.

  11. Boundary-Layer-Ingesting Inlet Flow Control

    NASA Technical Reports Server (NTRS)

    Owens, Lewis R.; Allan, Brian G.; Gorton, Susan A.

    2006-01-01

    This paper gives an overview of a research study conducted in support of the small-scale demonstration of an active flow control system for a boundary-layer-ingesting (BLI) inlet. The effectiveness of active flow control in reducing engine inlet circumferential distortion was assessed using a 2.5% scale model of a 35% boundary-layer-ingesting flush-mounted, offset, diffusing inlet. This experiment was conducted in the NASA Langley 0.3-meter Transonic Cryogenic Tunnel at flight Mach numbers with a model inlet specifically designed for this type of testing. High mass flow actuators controlled the flow through distributed control jets providing the active flow control. A vortex generator point design configuration was also tested for comparison purposes and to provide a means to examine a hybrid vortex generator and control jets configuration. Measurements were made of the onset boundary layer, the duct surface static pressures, and the mass flow through the duct and the actuators. The distortion and pressure recovery were determined by 40 total pressure measurements on 8 rake arms each separated by 45 degrees and were located at the aerodynamic interface plane. The test matrix was limited to a maximum free-stream Mach number of 0.85 with scaled mass flows through the inlet for that condition. The data show that the flow control jets alone can reduce circumferential distortion (DPCP(sub avg)) from 0.055 to about 0.015 using about 2.5% of inlet mass flow. The vortex generators also reduced the circumferential distortion from 0.055 to 0.010 near the inlet mass flow design point. Lower inlet mass flow settings with the vortex generator configuration produced higher distortion levels that were reduced to acceptable levels using a hybrid vortex generator/control jets configuration that required less than 1% of the inlet mass flow.

  12. Boundary layer control of rotating convection systems.

    PubMed

    King, Eric M; Stellmach, Stephan; Noir, Jerome; Hansen, Ulrich; Aurnou, Jonathan M

    2009-01-15

    Turbulent rotating convection controls many observed features of stars and planets, such as magnetic fields, atmospheric jets and emitted heat flux patterns. It has long been argued that the influence of rotation on turbulent convection dynamics is governed by the ratio of the relevant global-scale forces: the Coriolis force and the buoyancy force. Here, however, we present results from laboratory and numerical experiments which exhibit transitions between rotationally dominated and non-rotating behaviour that are not determined by this global force balance. Instead, the transition is controlled by the relative thicknesses of the thermal (non-rotating) and Ekman (rotating) boundary layers. We formulate a predictive description of the transition between the two regimes on the basis of the competition between these two boundary layers. This transition scaling theory unifies the disparate results of an extensive array of previous experiments, and is broadly applicable to natural convection systems.

  13. Boundary layer control of rotating convection systems.

    PubMed

    King, Eric M; Stellmach, Stephan; Noir, Jerome; Hansen, Ulrich; Aurnou, Jonathan M

    2009-01-15

    Turbulent rotating convection controls many observed features of stars and planets, such as magnetic fields, atmospheric jets and emitted heat flux patterns. It has long been argued that the influence of rotation on turbulent convection dynamics is governed by the ratio of the relevant global-scale forces: the Coriolis force and the buoyancy force. Here, however, we present results from laboratory and numerical experiments which exhibit transitions between rotationally dominated and non-rotating behaviour that are not determined by this global force balance. Instead, the transition is controlled by the relative thicknesses of the thermal (non-rotating) and Ekman (rotating) boundary layers. We formulate a predictive description of the transition between the two regimes on the basis of the competition between these two boundary layers. This transition scaling theory unifies the disparate results of an extensive array of previous experiments, and is broadly applicable to natural convection systems. PMID:19148097

  14. Cryptographic Enforcement of Role-Based Access Control

    NASA Astrophysics Data System (ADS)

    Crampton, Jason

    Many cryptographic schemes have been designed to enforce information flow policies. However, enterprise security requirements are often better encoded, or can only be encoded, using role-based access control policies rather than information flow policies. In this paper, we provide an alternative formulation of role-based access control that enables us to apply existing cryptographic schemes to core and hierarchical role-based access control policies. We then show that special cases of our cryptographic enforcement schemes for role-based access control are equivalent to cryptographic enforcement schemes for temporal access control and to ciphertext-policy and key-policy attribute-based encryption schemes. Finally, we describe how these special cases can be extended to support richer forms of temporal access control and attribute-based encryption.

  15. Health information system access control redesign - rationale and method.

    PubMed

    Moselle, Kenneth A

    2011-01-01

    This paper addresses the question of why a health service system might find it necessary to re-engineer the access control model that mediates the interaction of clinicians with health information systems. Factors that lead to increasingly complexity of the access control models are delineated, and consequences of that complexity are identified. Strategies are presented to address these factors, and a stepwise procedure is suggested to structure the access control model re-engineering process.

  16. Open versus Controlled-Access Data | Office of Cancer Genomics

    Cancer.gov

    OCG employs stringent human subjects’ protection and data access policies to protect the privacy and confidentiality of the research participants. Depending on the risk of patient identification, OCG programs data are available to the scientific community in two tiers: open or controlled access. Both types of data can be accessed through its corresponding OCG program-specific data matrix or portal. Open-access Data

  17. 49 CFR 1542.207 - Access control systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 9 2014-10-01 2014-10-01 false Access control systems. 1542.207 Section 1542.207..., DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control systems. (a) Secured area. Except as provided in paragraph (b) of this section, the measures...

  18. 49 CFR 1542.207 - Access control systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 9 2013-10-01 2013-10-01 false Access control systems. 1542.207 Section 1542.207..., DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control systems. (a) Secured area. Except as provided in paragraph (b) of this section, the measures...

  19. 49 CFR 1542.207 - Access control systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 9 2011-10-01 2011-10-01 false Access control systems. 1542.207 Section 1542.207..., DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control systems. (a) Secured area. Except as provided in paragraph (b) of this section, the measures...

  20. 49 CFR 1542.207 - Access control systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 9 2010-10-01 2010-10-01 false Access control systems. 1542.207 Section 1542.207..., DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control systems. (a) Secured area. Except as provided in paragraph (b) of this section, the measures...

  1. 49 CFR 1542.207 - Access control systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 9 2012-10-01 2012-10-01 false Access control systems. 1542.207 Section 1542.207..., DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control systems. (a) Secured area. Except as provided in paragraph (b) of this section, the measures...

  2. The Comparative Analysis of Main Access Control Technologies

    NASA Astrophysics Data System (ADS)

    Zhang, Su; Niu, Li; Chen, Jing

    Effective access control security design is an important precondition for the stable running of an information system. So it's necessary to establish a well-designed security mechanism to ensure the security of the system. This paper analysis and compares the main access control theories.

  3. Analysis of Access Control Policies in Operating Systems

    ERIC Educational Resources Information Center

    Chen, Hong

    2009-01-01

    Operating systems rely heavily on access control mechanisms to achieve security goals and defend against remote and local attacks. The complexities of modern access control mechanisms and the scale of policy configurations are often overwhelming to system administrators and software developers. Therefore, mis-configurations are common, and the…

  4. Boundary Layer Control for Hypersonic Airbreathing Vehicles

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Nowak, Robert J.; Horvath, Thomas J.

    2004-01-01

    Active and passive methods for tripping hypersonic boundary layers have been examined in NASA Langley Research Center wind tunnels using a Hyper-X model. This investigation assessed several concepts for forcing transition, including passive discrete roughness elements and active mass addition (or blowing), in the 20-Inch Mach 6 Air and the 31-Inch Mach 10 Air Tunnels. Heat transfer distributions obtained via phosphor thermography, shock system details, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. The comparisons between the active and passive methods for boundary layer control were conducted at test conditions that nearly match the Hyper-X nominal Mach 7 flight test-point of an angle-of-attack of 2-deg and length Reynolds number of 5.6 million. For passive roughness, the primary parametric variation was a range of trip heights within the calculated boundary layer thickness for several trip concepts. The passive roughness study resulted in a swept ramp configuration, scaled to be roughly 0.6 of the calculated boundary layer thickness, being selected for the Mach 7 flight vehicle. For the active blowing study, the manifold pressure was systematically varied (while monitoring the mass flow) for each configuration to determine the jet penetration height, with schlieren, and transition movement, with the phosphor system, for comparison to the passive results. All the blowing concepts tested, which included various rows of sonic orifices (holes), two- and three-dimensional slots, and random porosity, provided transition onset near the trip location with manifold stagnation pressures on the order of 40 times the model surface static pressure, which is adequate to ensure sonic jets. The present results indicate that the jet penetration height for blowing was roughly half the height required with passive roughness elements for an equivalent amount of transition movement.

  5. Task Delegation Based Access Control Models for Workflow Systems

    NASA Astrophysics Data System (ADS)

    Gaaloul, Khaled; Charoy, François

    e-Government organisations are facilitated and conducted using workflow management systems. Role-based access control (RBAC) is recognised as an efficient access control model for large organisations. The application of RBAC in workflow systems cannot, however, grant permissions to users dynamically while business processes are being executed. We currently observe a move away from predefined strict workflow modelling towards approaches supporting flexibility on the organisational level. One specific approach is that of task delegation. Task delegation is a mechanism that supports organisational flexibility, and ensures delegation of authority in access control systems. In this paper, we propose a Task-oriented Access Control (TAC) model based on RBAC to address these requirements. We aim to reason about task from organisational perspectives and resources perspectives to analyse and specify authorisation constraints. Moreover, we present a fine grained access control protocol to support delegation based on the TAC model.

  6. Managed Access by Controlled Sensing (MACS)

    SciTech Connect

    Curtiss, J.A.; Indusi, J.P.

    1994-08-01

    During chemical weapons challenge inspections, the CWC treaty allows ``alternate means`` of access to be proposed by the nation challenged. BNL`s Safeguards, Safety and Nonproliferation Division is funded by the Defense Nuclear Agency to develop a system to provide the challenge inspection team with a ``virtual presence`` within the facility while denying personal access. A general purpose configuration of a mobile station manned by site personnel and a base station manned by the challenge inspector, supported by a flexible communication system, will allow facility personnel to tailor the basic model to their site. Design of the MACS system is based on maximum use of commercial equipment that is available on the international market. Design requirements for the MACS system include methods of establishing geographical position, distance measuring equipment for use in verifying dimensions on floor plans, video and two-way audio links between the mobile unit and the base station, and portability and versatility of the equipment. The MACS platform will also support deployment of selected instrumentation which the site may offer to the challenge inspection team. This paper describes the design and construction of the prototype MACS system.

  7. Healthcare professionals' experiences with EHR-system access control mechanisms.

    PubMed

    Faxvaag, Arild; Johansen, Trond S; Heimly, Vigdis; Melby, Line; Grimsmo, Anders

    2011-01-01

    Access control mechanisms might influence on the information seeking and documentation behavior of clinicians. In this study, we have surveyed healthcare professionals in nursing homes and hospitals on their attitudes to, and experiences with using access control mechanisms. In some situations, the access control mechanisms of the EHR system made clinicians postpone documentation work. Their practice of reading what others have documented was also influenced. Not all clinicians logged out of the system when they left a workstation, and some clinicians reported to do some of their documentation work in the name of others. The reported practices might have implications for the safety of the patient.

  8. Urban Studies: A Study of Bibliographic Access and Control.

    ERIC Educational Resources Information Center

    Anderson, Barbara E.

    This paper analyzes: (1) the bibliographic access to publications in urban studies via printed secondary sources; (2) development and scope of classification systems and of vocabulary control for urban studies; and (3) currently accessible automated collections of bibliographic citations. Urban studies is defined as "an agglomeration of…

  9. Personnel Access Control System Evaluation for National Ignition Facility Operations

    SciTech Connect

    Altenbach, T; Brereton, S.; Hermes, G.; Singh, M.

    2001-06-01

    The purpose of this document is to analyze the baseline Access Control System for the National Ignition Facility (NIF), and to assess its effectiveness at controlling access to hazardous locations during full NIF operations. It reviews the various hazards present during a NIF shot sequence, and evaluates the effectiveness of the applicable set of controls at preventing access while the hazards are present. It considers only those hazards that could potentially be lethal. In addition, various types of technologies that might be applicable at NIF are reviewed, as are systems currently in use at other facilities requiring access control for safety reasons. Recommendations on how this system might be modified to reduce risk are made.

  10. PAL: An Object Oriented Data Access Layer for Herschel Data Processing

    NASA Astrophysics Data System (ADS)

    Li, B.; Guest, S.; Huang, M.; Balm, P.; Siddiqui, H.; Bakker, J.; Segovia, J. C.; Saiz, J.; Edwards, K.

    2012-09-01

    The Herschel Ground Segment Product Access Layer (PAL), an object oriented software package that provides a consistent means for accessing Herschel Space Observatory data products, isolates the complexity of underlying storage systems and makes it possible for scientific data analysis scripts to be reused in different environments and over a long period of time as software and hardware evolve. The pluggable design of the PAL makes it easier for users to handle new underlying storage systems and to optimize performance according to different system characteristics.

  11. Accessible Gaming through Mainstreaming Kinetic Controller

    NASA Astrophysics Data System (ADS)

    Garrido, Yolanda; Marco, Álvaro; Segura, Joaquín; Blanco, Teresa; Casas, Roberto

    Leisure is a very important aspect in our everyday life; and gaming is one of the main ways to it. Depending on the particular situation of each person, the way of playing could be very different. Motivation, preferences, skills, knowledge are some of the factors that influences this experience. When the person has a disability, additional agents come to scene such as cognitive level and mobility. Besides the design of the game, these factors clearly affect how the person interacts with the game; its user interface. In this paper we present a tool that allows people with disabilities to play games with a normalized user interface. This tool a) manages several wireless kinetic remote controllers, e.g. the Wiimotes; b) can be configured to capture any voluntary movements users could do and c) convert them into the specific inputs required by existing adapted games. As a result, users with disabilities can experience and enjoy games that were previously inaccessible to them.

  12. Control with a random access protocol and packet dropouts

    NASA Astrophysics Data System (ADS)

    Wang, Liyuan; Guo, Ge

    2016-08-01

    This paper investigates networked control systems whose actuators communicate with the controller via a limited number of unreliable channels. The access to the channels is decided by a so-called group random access protocol, which is modelled as a binary Markov sequence. Data packet dropouts in the channels are modelled as independent Bernoulli processes. For such systems, a systematic characterisation for controller synthesis is established and stated in terms of the transition probabilities of the Markov protocol and the packet dropout probabilities. The results are illustrated via a numerical example.

  13. Evaluating the effectiveness of biometric access control systems

    NASA Astrophysics Data System (ADS)

    Lively, Valerie M.

    2005-05-01

    This paper describes the contribution by the National Safe Skies Alliance (Safe Skies) in operational testing of biometric access control systems under the guidance of the Transportation Security Administration (TSA). Safe Skies has been conducting operational tests of biometric access control systems on behalf of the TSA for approximately four years. The majority of this testing has occurred at the McGhee Tyson Airport (TYS) in Knoxville, Tennessee. Twelve separate biometric devices - eight fingerprint, facial, iris, hand geometry, and fingerprint and iris, have been tested to date. Tests were conducted at a TYS administrative door and different airports to evaluate the access control device under normal, abnormal, and attempt-to-defeat conditions.

  14. Secondary retention of rubber dam: effective moisture control access considerations.

    PubMed

    Liebenberg, W H

    1995-04-01

    Primary rubber dam retention affects attachment of the latex sheet to the anchor teeth bordering the isolated working field. Secondary rubber dam retention is the provision of an effective seal at the dam-tooth junction, which is essential to the maintenance of adequate access and moisture control within the working field. Practical hints are offered to optimize access and moisture control through well-planned and properly executed secondary retention of classic rubber dam applications. In addition, innovative solutions to the limitations of general field isolation, which pertain mostly to secondary retention of the unrestrained buccal and lingual curtains of the slit dam, are introduced.

  15. Access and control of information and intellectual property

    NASA Astrophysics Data System (ADS)

    Lang, Gerald S.

    1996-03-01

    This paper introduces the technology of two pioneering patents for the secure distribution of information and intellectual property. The seminal technology has been used in the control of sensitive material such as medical records and imagery in distributed networks. It lends itself to the implementation of an open architecture access control system that provides local or remote user selective access to digital information stored on any computer system or storage medium, down to the data element, pixel, and sub-pixel levels. Use of this technology is especially suited for electronic publishing, health care records, MIS, and auditing.

  16. A Service Access Security Control Model in Cyberspace

    NASA Astrophysics Data System (ADS)

    Qianmu, Li; Jie, Yin; Jun, Hou; Jian, Xu; Hong, Zhang; Yong, Qi

    A service access control model in cyberspace is proposed, which provides a generalized and effective mechanism of security management with some items constraint specifications. These constraint specifications are organized to form a construction, and an enact process is proposed to make it scalable and flexible to meet the need of diversified service application systems in cyberspace. The model of this paper erases the downward information flow by extended rules of read/write, which is the breakthrough of the limitations when applying the standard role-based access control in cyberspace.

  17. Controlling user access to electronic resources without password

    SciTech Connect

    Smith, Fred Hewitt

    2015-06-16

    Described herein are devices and techniques for remotely controlling user access to a restricted computer resource. The process includes pre-determining an association of the restricted computer resource and computer-resource-proximal environmental information. Indicia of user-proximal environmental information are received from a user requesting access to the restricted computer resource. Received indicia of user-proximal environmental information are compared to associated computer-resource-proximal environmental information. User access to the restricted computer resource is selectively granted responsive to a favorable comparison in which the user-proximal environmental information is sufficiently similar to the computer-resource proximal environmental information. In at least some embodiments, the process further includes comparing user-supplied biometric measure and comparing it with a predetermined association of at least one biometric measure of an authorized user. Access to the restricted computer resource is granted in response to a favorable comparison.

  18. Error Control with Perfectly Matched Layer or Damping Layer Treatments for Computational Aeroacoustics with Jet Flows

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    2009-01-01

    In this paper we show by means of numerical experiments that the error introduced in a numerical domain because of a Perfectly Matched Layer or Damping Layer boundary treatment can be controlled. These experimental demonstrations are for acoustic propagation with the Linearized Euler Equations with both uniform and steady jet flows. The propagating signal is driven by a time harmonic pressure source. Combinations of Perfectly Matched and Damping Layers are used with different damping profiles. These layer and profile combinations allow the relative error introduced by a layer to be kept as small as desired, in principle. Tradeoffs between error and cost are explored.

  19. Accessibility, stabilizability, and feedback control of continuous orbital transfer.

    PubMed

    Gurfil, Pini

    2004-05-01

    This paper investigates the problem of low-thrust orbital transfer using orbital element feedback from a control-theoretic standpoint, concepts of controllability, feedback stabilizability, and their interaction. The Gauss variational equations (GVEs) are used to model the state-space dynamics. First, the notion of accessibility, a weaker form of controllability, is presented. It is then shown that the GVEs are globally accessible. Based on the accessibility result, a nonlinear feedback controller is derived that asymptotically steers a vehicle from an initial elliptic Keplerian orbit to any given elliptic Keplerian orbit. The performance of the new controller is illustrated by simulating an orbital transfer between two geosynchronous Earth orbits. It is shown that the low-thrust controller requires less fuel than an impulsive maneuver for the same transfer time. Closed-form, analytic expressions for the new orbital transfer controller are given. Finally, it is proved, based on a topological nonlinear stabilizability test, that there does not exist a continuous closed-loop controller that can transfer a spacecraft to a parabolic escape trajectory.

  20. Joint Access Control Based on Access Ratio and Resource Utilization for High-Speed Railway Communications

    NASA Astrophysics Data System (ADS)

    Zhou, Yuzhe; Ai, Bo

    2015-05-01

    The fast development of high-speed rails makes people's life more and more convenient. However, provisioning of quality of service of multimedia applications for users on the high-speed train is a critical task for wireless communications. Therefore, new solutions are desirable to be found to address this kind of problem. Current researches mainly focus on providing seamless broadband wireless access for high-speed mobile terminals. In this paper, an algorithm to calculate the optimal resource reservation fraction of handovers is proposed. A joint access control scheme for high-speed railway communication handover scenario is proposed. Metrics of access ratio and resource utilization ratio are considered jointly in the analysis and the performance evaluation. Simulation results show that the proposed algorithm and the scheme improve quality of service compared with other conventional schemes.

  1. Access Control for Mobile Assessment Systems Using ID.

    PubMed

    Nakayama, Masaharu; Ishii, Tadashi; Morino, Kazuma

    2015-01-01

    The assessment of shelters during disaster is critical to ensure the health of evacuees and prevent pandemic. In the Ishinomaki area, one of the areas most damaged by the Great East Japan Earthquake, the highly organized assessment helped to successfully manage a total of 328 shelters with a total of 46,480 evacuees. The input and analysis of vast amounts of data was tedious work for staff members. However, a web-based assessment system that utilized mobile devices was thought to decrease workload and standardize the evaluation form. The necessary access of information should be controlled in order to maintain individuals' privacy. We successfully developed an access control system using IDs. By utilizing a unique numerical ID, users can access the input form or assessment table. This avoids unnecessary queries to the server, resulting in a quick response and easy availability, even with poor internet connection. PMID:26262204

  2. Access Control for Agent-based Computing: A Distributed Approach.

    ERIC Educational Resources Information Center

    Antonopoulos, Nick; Koukoumpetsos, Kyriakos; Shafarenko, Alex

    2001-01-01

    Discusses the mobile software agent paradigm that provides a foundation for the development of high performance distributed applications and presents a simple, distributed access control architecture based on the concept of distributed, active authorization entities (lock cells), any combination of which can be referenced by an agent to provide…

  3. Research on a dynamic workflow access control model

    NASA Astrophysics Data System (ADS)

    Liu, Yiliang; Deng, Jinxia

    2007-12-01

    In recent years, the access control technology has been researched widely in workflow system, two typical technologies of that are RBAC (Role-Based Access Control) and TBAC (Task-Based Access Control) model, which has been successfully used in the role authorizing and assigning in a certain extent. However, during the process of complicating a system's structure, these two types of technology can not be used in minimizing privileges and separating duties, and they are inapplicable when users have a request of frequently changing on the workflow's process. In order to avoid having these weakness during the applying, a variable flow dynamic role_task_view (briefly as DRTVBAC) of fine-grained access control model is constructed on the basis existed model. During the process of this model applying, an algorithm is constructed to solve users' requirements of application and security needs on fine-grained principle of privileges minimum and principle of dynamic separation of duties. The DRTVBAC model is implemented in the actual system, the figure shows that the task associated with the dynamic management of role and the role assignment is more flexible on authority and recovery, it can be met the principle of least privilege on the role implement of a specific task permission activated; separated the authority from the process of the duties completing in the workflow; prevented sensitive information discovering from concise and dynamic view interface; satisfied with the requirement of the variable task-flow frequently.

  4. Fine-Grained Access Control for Electronic Health Record Systems

    NASA Astrophysics Data System (ADS)

    Hue, Pham Thi Bach; Wohlgemuth, Sven; Echizen, Isao; Thuy, Dong Thi Bich; Thuc, Nguyen Dinh

    There needs to be a strategy for securing the privacy of patients when exchanging health records between various entities over the Internet. Despite the fact that health care providers such as Google Health and Microsoft Corp.'s Health Vault comply with the U.S Health Insurance Portability and Accountability Act (HIPAA), the privacy of patients is still at risk. Several encryption schemes and access control mechanisms have been suggested to protect the disclosure of a patient's health record especially from unauthorized entities. However, by implementing these approaches, data owners are not capable of controlling and protecting the disclosure of the individual sensitive attributes of their health records. This raises the need to adopt a secure mechanism to protect personal information against unauthorized disclosure. Therefore, we propose a new Fine-grained Access Control (FGAC) mechanism that is based on subkeys, which would allow a data owner to further control the access to his data at the column-level. We also propose a new mechanism to efficiently reduce the number of keys maintained by a data owner in cases when the users have different access privileges to different columns of the data being shared.

  5. 33 CFR 106.260 - Security measures for access control.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the unauthorized introduction of dangerous substances and devices, including any device intended to... with the individual's claim of loss or theft. (3) If an individual cannot present his or her TWIC for... approved Facility Security Plan (FSP) the frequency of application of any access controls, particularly...

  6. 33 CFR 106.260 - Security measures for access control.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... the unauthorized introduction of dangerous substances and devices, including any device intended to... with the individual's claim of loss or theft. (3) If an individual cannot present his or her TWIC for... approved Facility Security Plan (FSP) the frequency of application of any access controls, particularly...

  7. Secure Dynamic access control scheme of PHR in cloud computing.

    PubMed

    Chen, Tzer-Shyong; Liu, Chia-Hui; Chen, Tzer-Long; Chen, Chin-Sheng; Bau, Jian-Guo; Lin, Tzu-Ching

    2012-12-01

    With the development of information technology and medical technology, medical information has been developed from traditional paper records into electronic medical records, which have now been widely applied. The new-style medical information exchange system "personal health records (PHR)" is gradually developed. PHR is a kind of health records maintained and recorded by individuals. An ideal personal health record could integrate personal medical information from different sources and provide complete and correct personal health and medical summary through the Internet or portable media under the requirements of security and privacy. A lot of personal health records are being utilized. The patient-centered PHR information exchange system allows the public autonomously maintain and manage personal health records. Such management is convenient for storing, accessing, and sharing personal medical records. With the emergence of Cloud computing, PHR service has been transferred to storing data into Cloud servers that the resources could be flexibly utilized and the operation cost can be reduced. Nevertheless, patients would face privacy problem when storing PHR data into Cloud. Besides, it requires a secure protection scheme to encrypt the medical records of each patient for storing PHR into Cloud server. In the encryption process, it would be a challenge to achieve accurately accessing to medical records and corresponding to flexibility and efficiency. A new PHR access control scheme under Cloud computing environments is proposed in this study. With Lagrange interpolation polynomial to establish a secure and effective PHR information access scheme, it allows to accurately access to PHR with security and is suitable for enormous multi-users. Moreover, this scheme also dynamically supports multi-users in Cloud computing environments with personal privacy and offers legal authorities to access to PHR. From security and effectiveness analyses, the proposed PHR access

  8. Access control and privacy in large distributed systems

    NASA Technical Reports Server (NTRS)

    Leiner, B. M.; Bishop, M.

    1986-01-01

    Large scale distributed systems consists of workstations, mainframe computers, supercomputers and other types of servers, all connected by a computer network. These systems are being used in a variety of applications including the support of collaborative scientific research. In such an environment, issues of access control and privacy arise. Access control is required for several reasons, including the protection of sensitive resources and cost control. Privacy is also required for similar reasons, including the protection of a researcher's proprietary results. A possible architecture for integrating available computer and communications security technologies into a system that meet these requirements is described. This architecture is meant as a starting point for discussion, rather that the final answer.

  9. Distributed reservation control protocols for random access broadcasting channels

    NASA Technical Reports Server (NTRS)

    Greene, E. P.; Ephremides, A.

    1981-01-01

    Attention is given to a communication network consisting of an arbitrary number of nodes which can communicate with each other via a time-division multiple access (TDMA) broadcast channel. The reported investigation is concerned with the development of efficient distributed multiple access protocols for traffic consisting primarily of single packet messages in a datagram mode of operation. The motivation for the design of the protocols came from the consideration of efficient multiple access utilization of moderate to high bandwidth (4-40 Mbit/s capacity) communication satellite channels used for the transmission of short (1000-10,000 bits) fixed length packets. Under these circumstances, the ratio of roundtrip propagation time to packet transmission time is between 100 to 10,000. It is shown how a TDMA channel can be adaptively shared by datagram traffic and constant bandwidth users such as in digital voice applications. The distributed reservation control protocols described are a hybrid between contention and reservation protocols.

  10. Tag Content Access Control with Identity-based Key Exchange

    NASA Astrophysics Data System (ADS)

    Yan, Liang; Rong, Chunming

    2010-09-01

    Radio Frequency Identification (RFID) technology that used to identify objects and users has been applied to many applications such retail and supply chain recently. How to prevent tag content from unauthorized readout is a core problem of RFID privacy issues. Hash-lock access control protocol can make tag to release its content only to reader who knows the secret key shared between them. However, in order to get this shared secret key required by this protocol, reader needs to communicate with a back end database. In this paper, we propose to use identity-based secret key exchange approach to generate the secret key required for hash-lock access control protocol. With this approach, not only back end database connection is not needed anymore, but also tag cloning problem can be eliminated at the same time.

  11. Control and Identification of Turbulent Boundary Layer Separation

    NASA Technical Reports Server (NTRS)

    Seifert, Avi; Pack-Melton, La Tunia

    2004-01-01

    Effective delay of turbulent boundary layer separation could be achieved via closed-loop control. Constructing such a system requires that sensor data be processed, real-time, and fed into the controller to determine the output. Current methods for detection of turbulent boundary layer separation are lacking the capability of localized, fast and reliable identification of the boundary layer state. A method is proposed for short-time FFT processing of time series, measured by hot-film sensors, with the purpose of identifying the alternation of the balance between small and large scales as the boundary layer separates, favoring the large scales. The method has been validated by comparison to other criteria of separation detection and over a range of baseline and controlled flow conditions on a simplified high-lift system, incorporating active flow control.

  12. Rural providers' access to online resources: a randomized controlled trial

    PubMed Central

    Hall, Laura J.; McElfresh, Karen R.; Warner, Teddy D.; Stromberg, Tiffany L.; Trost, Jaren; Jelinek, Devin A.

    2016-01-01

    Objective The research determined the usage and satisfaction levels with one of two point-of-care (PoC) resources among health care providers in a rural state. Methods In this randomized controlled trial, twenty-eight health care providers in rural areas were stratified by occupation and region, then randomized into either the DynaMed or the AccessMedicine study arm. Study participants were physicians, physician assistants, and nurses. A pre- and post-study survey measured participants' attitudes toward different information resources and their information-seeking activities. Medical student investigators provided training and technical support for participants. Data analyses consisted of analysis of variance (ANOVA), paired t tests, and Cohen's d statistic to compare pre- and post-study effects sizes. Results Participants in both the DynaMed and the AccessMedicine arms of the study reported increased satisfaction with their respective PoC resource, as expected. Participants in both arms also reported that they saved time in finding needed information. At baseline, both arms reported too little information available, which increased to “about right amounts of information” at the completion of the study. DynaMed users reported a Cohen's d increase of +1.50 compared to AccessMedicine users' reported use of 0.82. DynaMed users reported d2 satisfaction increases of 9.48 versus AccessMedicine satisfaction increases of 0.59 using a Cohen's d. Conclusion Participants in the DynaMed arm of the study used this clinically oriented PoC more heavily than the users of the textbook-based AccessMedicine. In terms of user satisfaction, DynaMed users reported higher levels of satisfaction than the users of AccessMedicine. PMID:26807050

  13. Potential COntrol Under Thin Aqueous Layers Using a Kelvin Probe

    SciTech Connect

    G.S. Frankel; B. Maier; M. Stratman; M. Rohwerder; A. Michalik; J. Dora; M. Wicinski

    2006-08-17

    Kelvin Probes can be modified to control as well as monitor potential. The design and operation of two different Kelvin Probe Potentiostats (KPPs) are described in this paper. One approach uses a permanent magnet and double coil to oscillate the needle at a fixed frequency, an AC backing potential, and software analysis and control schemes. This technique can also control the distance between the tip and sample, thereby tracking the topography of the sample. Both KPPs were used to make measurements on Type 304L stainless steel under thin layers of electrolyte. Cathodic polarization curves exhibited a limiting current density associated with oxygen reduction. The limiting current density varied with solution layer thickness over a finite range of thickness. Anodic polarization curves on 304L in a thin layer of chloride solution resulted in pitting corrosion. The breakdown potential did not vary with solution layer thickness. However, the thin layer was observed to increase in volume remarkably during pit growth owing to the absorption of water from the high humidity environment into the layer with ionic strength increased by the pit dissolution. The open circuit potential (OCP) and solution layer thickness were monitored during drying out of a thin electrolyte layer. Pitting corrosion initiated, as indicated by a sharp drop in the OCP, as the solution thinned and increased in concentration.

  14. Authorisation and access control for electronic health record systems.

    PubMed

    Blobel, Bernd

    2004-03-31

    Enabling the shared care paradigm, centralised or even decentralised electronic health record (EHR) systems increasingly become core applications in hospital information systems and health networks. For realising multipurpose use and reuse as well as inter-operability at knowledge level, EHR have to meet special architectural requirements. The component-oriented and model-based architecture should meet international standards. Especially in extended health networks realising inter-organisational communication and co-operation, authorisation cannot be organised at user level anymore. Therefore, models, methods and tools must be established to allow formal and structured policy definition, policy agreements, role definition, authorisation and access control. Based on the author's international engagement in EHR architecture and security standards referring to the revision of CEN ENV 13606, the GEHR/open EHR approach, HL7 and CORBA, models for health-specific and EHR-related roles, for authorisation management and access control have been developed. The basic concept is the separation of structural roles defining organisational entity-to-entity relationships and enabling specific acts on the one hand, and functional roles bound to specific activities and realising rights and duties on the other hand. Aggregation of organisational, functional, informational and technological components follows specific rules. Using UML and XML, the principles as well as some examples for analysis, design, implementation and maintenance of policy and authorisation management as well as access control have been practically implemented. PMID:15066555

  15. Authorisation and access control for electronic health record systems.

    PubMed

    Blobel, Bernd

    2004-03-31

    Enabling the shared care paradigm, centralised or even decentralised electronic health record (EHR) systems increasingly become core applications in hospital information systems and health networks. For realising multipurpose use and reuse as well as inter-operability at knowledge level, EHR have to meet special architectural requirements. The component-oriented and model-based architecture should meet international standards. Especially in extended health networks realising inter-organisational communication and co-operation, authorisation cannot be organised at user level anymore. Therefore, models, methods and tools must be established to allow formal and structured policy definition, policy agreements, role definition, authorisation and access control. Based on the author's international engagement in EHR architecture and security standards referring to the revision of CEN ENV 13606, the GEHR/open EHR approach, HL7 and CORBA, models for health-specific and EHR-related roles, for authorisation management and access control have been developed. The basic concept is the separation of structural roles defining organisational entity-to-entity relationships and enabling specific acts on the one hand, and functional roles bound to specific activities and realising rights and duties on the other hand. Aggregation of organisational, functional, informational and technological components follows specific rules. Using UML and XML, the principles as well as some examples for analysis, design, implementation and maintenance of policy and authorisation management as well as access control have been practically implemented.

  16. An approach to access control in electronic health record.

    PubMed

    Sucurovic, Snezana

    2010-08-01

    OASIS is a non-for-profit consortium that drives the development convergence and adoption of open standards for the global information society. It involves more than 600 organizations and individuals as well as IT leaders Sun, Microsoft, IBM and Oracle. One of its standards is XACML which appeared a few years ago and now there are about 150,000 hits on Google. XACML (eXtensible Access Control Markup Language) is not technology related. Sun published in 2004 open source Sun XACML which is in compliance with XACML 1.0. specification and now works to make it comply with XACML 2.0. The heart of XACML are attributes values of defined type and name that is to be attached to a subject, a resource, an action and an environment in which a subject request action on resource. In that way XACML is to replace Role Based Access Control which dominated for years. The paper examines performances in CEN 13 606 and ISO 22 600 based healthcare system which uses XACML for access control.

  17. Integration of access control and ancillary information systems

    SciTech Connect

    Rodriguez, J.R.; Ahrens, J.S.

    1995-07-01

    The DOE has identified the Lawrence Livermore National Laboratory ARGUS system as the standard entry control system for the DOE Complex. ARGUS integrates several key functions, specifically, badging, entry control, and verification of clearance status. Not all sites need or can afford an ARGUS system. Such sites are therefore limited to commercial equipment which provide ARGUS like features. In this project an alternative way to integrate commercial equipment into an integrated system to include badging, access control, property control, and automated verification of clearance status has been investigated. Such a system would provide smaller sites the same functionality as is provided by ARGUS. Further, it would allow sites to fully participate in the DOE`s concept of Complex wide access control. This multi-year task is comprised of three phases. Phase 1, system requirements and definitions, and phase 2, software and hardware development, were completed during fiscal year 1994. This report covers these two phases and the demonstration system which resulted. Phase three would employ the demonstration system to evaluate system performance, identify operational limits and to integrate additional features. The demonstration system includes a badging station, a database server, a managers workstation, an entry control system, and a property protection system. The functions have been integrated through the use of custom interfaces and operator screens which greatly increase ease of use.

  18. Controls on boundary layer ventilation: Boundary layer processes and large-scale dynamics

    NASA Astrophysics Data System (ADS)

    Sinclair, V. A.; Gray, S. L.; Belcher, S. E.

    2010-06-01

    Midlatitude cyclones are important contributors to boundary layer ventilation. However, it is uncertain how efficient such systems are at transporting pollutants out of the boundary layer, and variations between cyclones are unexplained. In this study 15 idealized baroclinic life cycles, with a passive tracer included, are simulated to identify the relative importance of two transport processes: horizontal divergence and convergence within the boundary layer and large-scale advection by the warm conveyor belt. Results show that the amount of ventilation is insensitive to surface drag over a realistic range of values. This indicates that although boundary layer processes are necessary for ventilation they do not control the magnitude of ventilation. A diagnostic for the mass flux out of the boundary layer has been developed to identify the synoptic-scale variables controlling the strength of ascent in the warm conveyor belt. A very high level of correlation (R2 values exceeding 0.98) is found between the diagnostic and the actual mass flux computed from the simulations. This demonstrates that the large-scale dynamics control the amount of ventilation, and the efficiency of midlatitude cyclones to ventilate the boundary layer can be estimated using the new mass flux diagnostic. We conclude that meteorological analyses, such as ERA-40, are sufficient to quantify boundary layer ventilation by the large-scale dynamics.

  19. Blow-up and control of marginally separated boundary layers.

    PubMed

    Braun, Stefan; Kluwick, Alfred

    2005-05-15

    Interactive solutions for steady two-dimensional laminar marginally separated boundary layers are known to exist up to a critical value Gamma(c) of the controlling parameter (e.g. the angle of attack of a slender airfoil) Gamma only. Here, we investigate three-dimensional unsteady perturbations of such boundary layers, assuming that the basic flow is almost critical, i.e. in the limit Gamma(c)-Gamma-->0. It is then shown that the interactive equations governing such perturbations simplify significantly, allowing, among others, a systematic study of the blow-up phenomenon observed in earlier investigations and the optimization of devices used in boundary-layer control.

  20. Boundary Layer Control of Rotating Convection Systems

    NASA Astrophysics Data System (ADS)

    King, E. M.; Stellmach, S.; Noir, J.; Hansen, U.; Aurnou, J. M.

    2008-12-01

    Rotating convection is ubiquitous in the natural universe, and is likely responsible for planetary processes such magnetic field generation. Rapidly rotating convection is typically organized by the Coriolis force into tall, thin, coherent convection columns which are aligned with the axis of rotation. This organizational effect of rotation is thought to be responsible for the strength and structure of magnetic fields generated by convecting planetary interiors. As thermal forcing is increased, the relative influence of rotation weakens, and fully three-dimensional convection can exist. It has long been assumed that rotational effects will dominate convection dynamics when the ratio of buoyancy to the Coriolis force, the convective Rossby number, Roc, is less than unity. We investigate the influence of rotation on turbulent Rayleigh-Benard convection via a suite of coupled laboratory and numerical experiments over a broad parameter range: Rayleigh number, 10310; Ekman number, 10-6≤ E ≤ ∞; and Prandtl number, 1≤ Pr ≤ 100. In particular, we measure heat transfer (as characterized by the Nusselt number, Nu) as a function of the Rayleigh number for several different Ekman and Prandtl numbers. Two distinct heat transfer scaling regimes are identified: non-rotating style heat transfer, Nu ~ Ra2/7, and quasigeostrophic style heat transfer, Nu~ Ra6/5. The transition between the non-rotating regime and the rotationally dominant regime is described as a function of the Ekman number, E. We show that the regime transition depends not on the global force balance Roc, but on the relative thicknesses of the thermal and Ekman boundary layers. The transition scaling provides a predictive criterion for the applicability of convection models to natural systems such as Earth's core.

  1. Hand geometry biometric device for secure access control

    SciTech Connect

    Colbert, C.; Moles, D.R. )

    1991-01-01

    This paper reports that the authors developed for the Air Force the Mark VI Personal Identity Verifier (PIV) for controlling access to a fixed or mobile ICBM site, a computer terminal, or mainframe. The Mark VI records the digitized silhouettes of four fingers of each hand on an AT and T smart card. Like fingerprints, finger shapes, lengths, and widths constitute an unguessable biometric password. A Security Officer enrolls an authorized person who places each hand, in turn, on a backlighted panel. An overhead scanning camera records the right and left hand reference templates on the smart card. The Security Officer adds to the card: name, personal identification number (PIN), and access restrictions such as permitted days of the week, times of day, and doors. To gain access, cardowner inserts card into a reader slot and places either hand on the panel. Resulting access template is matched to the reference template by three sameness algorithms. The final match score is an average of 12 scores (each of the four fingers, matched for shape, length, and width), expressing the degree of sameness. (A perfect match would score 100.00.) The final match score is compared to a predetermined score (threshold), generating an accept or reject decision.

  2. Global Access-controlled Transfer e-frame (GATe)

    SciTech Connect

    2012-05-30

    Global Access-controlled Transfer e-frame (GATe) was designed to take advantage of the patterns that occur during an electronic record transfer process. The e-frame (or electronic framework or platform) is the foundation for developing secure information transfer to meet classified and unclassified business processes and is particularly useful when there is a need to share information with various entities in a controlled and secure environment. It can share, search, upload, download and retrieve sensitive information, as well as provides reporting capabilities.

  3. Global Access-controlled Transfer e-frame (GATe)

    2012-05-30

    Global Access-controlled Transfer e-frame (GATe) was designed to take advantage of the patterns that occur during an electronic record transfer process. The e-frame (or electronic framework or platform) is the foundation for developing secure information transfer to meet classified and unclassified business processes and is particularly useful when there is a need to share information with various entities in a controlled and secure environment. It can share, search, upload, download and retrieve sensitive information, asmore » well as provides reporting capabilities.« less

  4. A study of multiple access schemes in satellite control network

    NASA Astrophysics Data System (ADS)

    Mo, Zijian; Wang, Zhonghai; Xiang, Xingyu; Wang, Gang; Chen, Genshe; Nguyen, Tien; Pham, Khanh; Blasch, Erik

    2016-05-01

    Satellite Control Networks (SCN) have provided launch control for space lift vehicles; tracking, telemetry and commanding (TTC) for on-orbit satellites; and, test support for space experiments since the 1960s. Currently, SCNs encounter a new challenge: how to maintain the high reliability of services when sharing the spectrum with emerging commercial services. To achieve this goal, the capability of multiple satellites reception is deserved as an update/modernization of SCN in the future. In this paper, we conducts an investigation of multiple access techniques in SCN scenario, e.g., frequency division multiple access (FDMA) and coded division multiple access (CDMA). First, we introduce two upgrade options of SCN based on FDMA and CDMA techniques. Correspondingly, we also provide their performance analysis, especially the system improvement in spectrum efficiency and interference mitigation. Finally, to determine the optimum upgrade option, this work uses CRISP, i.e., Cost, Risk, Installation, Supportability and Performance, as the baseline approach for a comprehensive trade study of these two options. Extensive numerical and simulation results are presented to illustrate the theoretical development.

  5. Dependence of reactive metal layer on resistive switching in a bi-layer structure Ta/HfOx filament type resistive random access memory

    NASA Astrophysics Data System (ADS)

    Lee, Daeseok; Woo, Jiyong; Park, Sangsu; Cha, Euijun; Lee, Sangheon; Hwang, Hyunsang

    2014-02-01

    The dependence of reactive metal layer on resistive switching characteristics is investigated in a bi-layer structural Ta/HfOx filament type resistive random access memory (ReRAM). By increasing the oxygen absorption rate of the reactive metal layer, formation of an induced resistive switching region that led to significant changes in the resistive switching characteristics of the ReRAM was observed. Electrical and physical analyses showed that the induced TaOx-resistive switching region can result in self-compliance behavior, uniform resistive switching, and a gradual set process, which can be utilized for low power and analog operations.

  6. Access Control Model for Sharing Composite Electronic Health Records

    NASA Astrophysics Data System (ADS)

    Jin, Jing; Ahn, Gail-Joon; Covington, Michael J.; Zhang, Xinwen

    The adoption of electronically formatted medical records, so called Electronic Health Records (EHRs), has become extremely important in healthcare systems to enable the exchange of medical information among stakeholders. An EHR generally consists of data with different types and sensitivity degrees which must be selectively shared based on the need-to-know principle. Security mechanisms are required to guarantee that only authorized users have access to specific portions of such critical record for legitimate purposes. In this paper, we propose a novel approach for modelling access control scheme for composite EHRs. Our model formulates the semantics and structural composition of an EHR document, from which we introduce a notion of authorized zones of the composite EHR at different granularity levels, taking into consideration of several important criteria such as data types, intended purposes and information sensitivities.

  7. What percentage of the oceanic mixed layer is accessible to marine Lidar? Global and the Gulf of Mexico prospective.

    PubMed

    Bogucki, D J; Spiers, G

    2013-10-01

    The oceanic mixed layer is a nearly homogenous region of the upper ocean which, in principle, has a little or no variation in turbulence strength, temperature or density with depth. This layer mediates oceanic fluxes of gas, momentum and heat. Here, based on the chosen marine Lidar system, we have carried out estimates of the depth penetration of the Lidar when compared to the local mixed layer depth. On average, we have found that at least 50% of the global oceanic mixed layer depth is accessible to the Lidar observations. When operating in a single scattering mode, which is more attenuating but more amenable to analysis, the modeled Lidar was found to access 0.4 of global mixed layer depth in half of the cases. The single scattering Lidar was found to access a large fraction of the equatorial mixed layer - a region very important when addressing global climatic issues. In a coastal environment such as the Gulf of Mexico the single scattering Lidar was found to penetrate upper half of the mixed layer, underscoring the potential for Lidar to address environmental issues there.

  8. Distributed joint power and access control algorithm for secondary spectrum sharing

    NASA Astrophysics Data System (ADS)

    Li, Hongyan; Chen, Enqing; Fu, Hongliang

    2010-08-01

    Based on interference temperature model, the problem of efficient secondary spectrum sharing is formulated as a power optimization problem with some constraints at physical layer. These constraints and optimization objective limit a feasible power vector set which leads to the need of access control besides power control. In this paper, we consider the decentralized cognitive radio network scenario where short-term data service is required, and the problem of distributed joint power and access control is studied to maximize the total secondary system throughput, subject to Quality of Service (QoS) constraints from individual secondary users and interference temperature limit (ITL) from primary system. Firstly, a pricing-based game model was used to solve distributed power allocation optimization problem in both high and low signal to interference noise ratio (SINR) scenarios. Secondly, when not all the secondary links can be supported with their QoS requirement and ITL, a distributed joint power and access control algorithm was introduced to find the allowable links which results in maximum network throughput with all the constraints satisfied, and the convergence performance is tested by simulations.

  9. Access Control of Cloud Service Based on UCON

    NASA Astrophysics Data System (ADS)

    Danwei, Chen; Xiuli, Huang; Xunyi, Ren

    Cloud computing is an emerging computing paradigm, and cloud service is also becoming increasingly relevant. Most research communities have recently embarked in the area, and research challenges in every aspect. This paper mainly discusses cloud service security. Cloud service is based on Web Services, and it will face all kinds of security problems including what Web Services face. The development of cloud service closely relates to its security, so the research of cloud service security is a very important theme. This paper introduces cloud computing and cloud service firstly, and then gives cloud services access control model based on UCON and negotiation technologies, and also designs the negotiation module.

  10. Privacy and Access Control for IHE-Based Systems

    NASA Astrophysics Data System (ADS)

    Katt, Basel; Breu, Ruth; Hafner, Micahel; Schabetsberger, Thomas; Mair, Richard; Wozak, Florian

    Electronic Health Record (EHR) is the heart element of any e-health system, which aims at improving the quality and efficiency of healthcare through the use of information and communication technologies. The sensitivity of the data contained in the health record poses a great challenge to security. In this paper we propose a security architecture for EHR systems that are conform with IHE profiles. In this architecture we are tackling the problems of access control and privacy. Furthermore, a prototypical implementation of the proposed model is presented.

  11. Efficient identity management and access control in cloud environment

    NASA Astrophysics Data System (ADS)

    Gloster, Jonathan

    2013-05-01

    As more enterprises are enticed to move data to a cloud environment to enhance data sharing and reduce operating costs by exploiting shared resources, concerns have risen over the ability to secure information within the cloud. This paper examines how a traditional Identity and Access Control (IDAM) architecture can be adapted to address security concerns of a cloud environment. We propose changing the paradigm of IDAM form a pure trust model to a risk based model will enable information to be protected securely in a cloud environment without impacting efficiencies of cloud environments.

  12. In situ imaging and control of layer-by-layer femtosecond laser thinning of graphene.

    PubMed

    Li, D W; Zhou, Y S; Huang, X; Jiang, L; Silvain, J-F; Lu, Y F

    2015-02-28

    Although existing methods (chemical vapor deposition, mechanical exfoliation, etc.) are available to produce graphene, the lack of thickness control limits further graphene applications. In this study, we demonstrate an approach to precisely thin graphene films to a specific thickness using femtosecond (fs) laser raster scanning. By using appropriate laser fluence and scanning times, graphene thinning with an atomic layer precision, namely layer-by-layer graphene removal, has been realized. The fs laser used was configured in a four-wave mixing (FWM) system which can be used to distinguish graphene layer thickness and count the number of layers using the linear relationship between the FWM signal intensity and the graphene thickness. Furthermore, FWM imaging has been successfully applied to achieve in situ, real-time monitoring of the fs laser graphene thinning process. This method can not only realize the large-scale thinning of graphene with atomic layer precision, but also provide in situ, rapid imaging capability of graphene for an accurate assessment of the number of layers.

  13. Passive and active control of boundary layer transition

    NASA Astrophysics Data System (ADS)

    Nosenchuck, Daniel Mark

    It is well known that laminar-turbulent boundary layer transition is initiated by the formation of Tollmien-Schlichting laminar instability waves. The amplification rates of these waves are strongly dependent on the shape of the boundary layer velocity profile. Consequently, the transition process can be controlled by modifying the velocity profile. This can be accomplished by controlling the pressure gradient (dp/dx), using boundary layer suction, installing surface roughness elements, or by surface heating or cooling. Methods used to modify the transition process through changes in the mean velocity profile are called "passive" in this paper. There exists a large set of experiments and theory on the application of passive methods for boundary layer control. In the present work only surface heating will be addressed.Transition measurements were made on a heated flat plate in water. Results are presented for several plate wall temperature distributions. An increase by a factor of 2.5 in transition Reynolds number was observed for a 5°C isothermal wall overheat. Buoyancy effects on transition were minimal due to the small Richardson and Grashof numbers encountered in the experiments.The amplification of laminar instability waves is comparatively to process, taking place over many boundary layer thicknesses. After the slow amplification of the laminar instability waves, transition occurs by a strong three dimensional dynamic instability. It appears possible to attenuate (or reinforce) the instability waves by introducing amplitude-and phase-controlled perturbations into the laminar boundary layer using feedback control system. This method is called "active" control and forms the larger part of the research reported in this thesis.A combination of sensors, activators and feedback control electronics is required for active control. The sensors used in the experiments are flush-mounted hot film wall shear robes. A new type of activator was developed using thin, flush

  14. A High Throughput Medium Access Control Implementation Based on IEEE 802.11e Standard

    NASA Astrophysics Data System (ADS)

    Huang, Min Li; Lee, Jin; Setiawan, Hendra; Ochi, Hiroshi; Park, Sin-Chong

    With the growing demand for high-performance multimedia applications over wireless channels, we need to develop a Medium Access Control (MAC) system that supports high throughput and quality of service enhancements. This paper presents the standard analysis, design architecture and design issues leading to the implementation of an IEEE 802.11e based MAC system that supports MAC throughput of over 100Mbps. In order to meet the MAC layer timing constraints, a hardware/software co-design approach is adopted. The proposed MAC architecture is implemented on the Xilinx Virtex-II Pro Field-Programmable Gate Array (FPGA) (XC2VP70-5FF1704C) prototype, and connected to a host computer through an external Universal Serial Bus (USB) interface. The total FPGA resource utilization is 11, 508 out of 33, 088 (34%) available slices. The measured MAC throughput is 100.7Mbps and 109.2Mbps for voice and video access categories, transmitted at a data rate of 260Mbps based on IEEE 802.11n Physical Layer (PHY), using the contention-based hybrid coordination function channel access mechanism.

  15. Chemical control of Ornithonyssus sylviarum on caged layer hens.

    PubMed

    Levot, G W

    1992-04-01

    Manual application of aqueous solutions of malathion, carbaryl and permethrin controlled northern fowl mite, Ornithonyssus sylviarum Canestrini and Fanzago, on caged layer hens for at least 118 days. Azamethiphos sprayed manually provided acceptable control for a shorter period. Machine application, particularly of azamethiphos, but also malathion, provided lesser control. The addition of surfactant increased the wetting ability of the sprays but interfered with the efficacy of azamethiphos. PMID:1421482

  16. Programmable light-controlled shape changes in layered polymer nanocomposites.

    PubMed

    Zhu, Zhichen; Senses, Erkan; Akcora, Pinar; Sukhishvili, Svetlana A

    2012-04-24

    We present soft, layered nanocomposites that exhibit controlled swelling anisotropy and spatially specific shape reconfigurations in response to light irradiation. The use of gold nanoparticles grafted with a temperature-responsive polymer (poly(N-isopropylacrylamide), PNIPAM) with layer-by-layer (LbL) assembly allowed placement of plasmonic structures within specific regions in the film, while exposure to light caused localized material deswelling by a photothermal mechanism. By layering PNIPAM-grafted gold nanoparticles in between nonresponsive polymer stacks, we have achieved zero Poisson's ratio materials that exhibit reversible, light-induced unidirectional shape changes. In addition, we report rheological properties of these LbL assemblies in their equilibrium swollen states. Moreover, incorporation of dissimilar plasmonic nanostructures (solid gold nanoparticles and nanoshells) within different material strata enabled controlled shrinkage of specific regions of hydrogels at specific excitation wavelengths. The approach is applicable to a wide range of metal nanoparticles and temperature-responsive polymers and affords many advanced build-in options useful in optically manipulated functional devices, including precise control of plasmonic layer thickness, tunability of shape variations to the excitation wavelength, and programmable spatial control of optical response. PMID:22452351

  17. Ionization behavior, stoichiometry of association, and accessibility of functional groups in the active layers of reverse osmosis and nanofiltration membranes.

    PubMed

    Coronell, Orlando; González, Mari I; Mariñas, Benito J; Cahill, David G

    2010-09-01

    We characterized the fully aromatic polyamide (PA) active layers of six commercial reverse osmosis (RO) and nanofiltration (NF) membranes and found that in contrast to their similar elemental composition, total concentration of functional groups, and degree of polymerization, the ionization behavior and spatial distribution of carboxylic (R-COOH) groups within the active layers can be significantly different. We also studied the steric effects experienced by barium ion (Ba2+) in the active layers by determining the fraction of carboxylate (R-COO-) groups accessible to Ba2+; such fraction, referred to as the accessibility ratio (AR), was found to vary within the range AR=0.40-0.81, and to be generally independent of external solution pH. Additionally, we studied an NF membrane with a sulfonated polyethersulfone (SPES) active layer, and found that the concentration of sulfonate (R-SO3-) groups in the active layer was 1.67 M, independent of external solution pH and approximately three times higher than the maximum concentration (approximately 0.45+/-0.25 M) of R-COO- groups in PA active layers. The R-SO3- groups were found to be highly accessible to Ba2+ (AR=0.95+/-0.01).

  18. Extending a Role Graph for Role-Based Access Control

    NASA Astrophysics Data System (ADS)

    Asakura, Yoshiharu; Nakamoto, Yukikazu

    Role-based access control (RBAC) is widely used as an access control mechanism in various computer systems. Since an organization's lines of authority influence the authorized privileges of jobs, roles also form a hierarchical structure. A role graph is a model that represents role hierarchies and is suitable for the runtime phase of RBAC deployment. Since a role graph cannot take various forms for given roles and cannot handle abstraction of roles well, however, it is not suitable for the design phase of RBAC deployment. Hence, an extended role graph, which can take a more flexible form than that of a role graph, is proposed. The extended role graph improves diversity and clarifies abstraction of roles, making it suitable for the design phase. An equivalent transformation algorithm (ETA), for transforming an extended role graph into an equivalent role graph, is also proposed. Using the ETA, system administrators can deploy efficiently RBAC by using an extended role graph in the design phase and a standard role graph in the runtime phase.

  19. Controllable preparation of multishelled NiO hollow nanospheres via layer-by-layer self-assembly for supercapacitor application

    NASA Astrophysics Data System (ADS)

    Yang, Zeheng; Xu, Feifei; Zhang, Weixin; Mei, Zhousheng; Pei, Bo; Zhu, Xiao

    2014-01-01

    In this work, we demonstrate a facile layer-by-layer (LBL) self-assembly method for controllable preparation of single-, double-, and triple-shelled NiO hollow nanospheres by calcining Ni(OH)2/C precursors formed at different stage. It is observed that the external nanoflakes of the NiO hollow nanospheres are inherited from the Ni(OH)2 precursors organized on the surface of carbon spheres via a self-assembly growth process and the inner shells result from the formation of different Ni(OH)2 layers within the carbon spheres during different preparation cycles. Supercapacitive performance of the three types of NiO hollow nanospheres as active electrode materials has been evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge. The results indicate that double-shelled NiO hollow nanosphere sample with largest surface area (92.99 m2 g-1) exhibits the best electrochemical properties among the three NiO hollow nanosphere samples. It delivers a high capacitance of 612.5 F g-1 at 0.5 A g-1 and demonstrates a superior long-term cyclic stability, with over 90% specific capacitance retention after 1000 charge-discharge cycles. This excellent performance is ascribed to the short diffusion path and large surface area of the unique hollow structure with nanoflake building blocks for bulk accessibility of faradaic reaction.

  20. Acoustic excitation: A promising new means of controlling shear layers

    NASA Technical Reports Server (NTRS)

    Stone, J. R.; Mckinzie, D. J., Jr.

    1984-01-01

    Techniques have long been sought for the controlled modification of turbulent shear layers, such as in jets, wakes, boundary layers, and separated flows. Relatively recently published results of laboratory experiments have established that coherent structures exist within turbulent flows. These results indicate that even apparently chaotic flow fields can contain deterministic, nonrandom elements. Even more recently published results show that deliberate acoustic excitation of these coherent structures has a significant effect on the mixing characteristics of shear layers. Therefore, we have initiated a research effort to develop both an understanding of the interaction mechanisms and the ability to use it to favorably modify various shear layers. Acoustic excitation circumvents the need for pumping significant flow rates, as required by suction or blowing. Control of flows by intentional excitation of natural flow instabilities involves new and largely unexplored phenomena and offers considerable potential for improving component performance. Nonintrusive techniques for flow field control may permit much more efficient, flexible propulsion systems and aircraft designs, including means of stall avoidance and recovery. The techniques developed may also find application in many other areas where mixing is important, such as reactors, continuous lasers, rocket engines, and fluidic devices. It is the objective of this paper to examine some potential applications of the acoustic excitation technique to various shear layer flows of practical aerospace systems.

  1. 76 FR 60398 - Exemption to Prohibition on Circumvention of Copyright Protection Systems for Access Control...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-29

    ... Prohibition on Circumvention of Copyright Protection Systems for Access Control Technologies, 68 FR 62011... Circumvention of Copyright Protection Systems for Access Control Technologies, 71 FR 68472, 68480, published in... Protection Systems for Access Control Technologies, 65 FR 64556, 64564, published in the Federal...

  2. 76 FR 67019 - Tenth Meeting: RTCA Special Committee 224, Airport Security Access Control

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-28

    ... Federal Aviation Administration Tenth Meeting: RTCA Special Committee 224, Airport Security Access Control... RTCA Special Committee 224, Airport Security Access Control. SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224, Airport Security Access Control. DATES:...

  3. Access control violation prevention by low-cost infrared detection

    NASA Astrophysics Data System (ADS)

    Rimmer, Andrew N.

    2004-09-01

    A low cost 16x16 un-cooled pyroelectric detector array, allied with advanced tracking and detection algorithms, has enabled the development of a universal detector with a wide range of applications in people monitoring and homeland security. Violation of access control systems, whether controlled by proximity card, biometrics, swipe card or similar, may occur by 'tailgating' or 'piggybacking' where an 'approved' entrant with a valid entry card is accompanied by a closely spaced 'non-approved' entrant. The violation may be under duress, where the accompanying person is attempting to enter a secure facility by force or threat. Alternatively, the violation may be benign where staff members collude either through habit or lassitude, either with each other or with third parties, without considering the security consequences. Examples of the latter could include schools, hospitals or maternity homes. The 16x16 pyroelectric array is integrated into a detector or imaging system which incorporates data processing, target extraction and decision making algorithms. The algorithms apply interpolation to the array output, allowing a higher level of resolution than might otherwise be expected from such a low resolution array. The pyroelectric detection principle means that the detection will work in variable light conditions and even in complete darkness, if required. The algorithms can monitor the shape, form, temperature and number of persons in the scene and utilise this information to determine whether a violation has occurred or not. As people are seen as 'hot blobs' and are not individually recognisable, civil liberties are not infringed in the detection process. The output from the detector is a simple alarm signal which may act as input to the access control system as an alert or to trigger CCTV image display and storage. The applications for a tailgate detector can be demonstrated across many medium security applications where there are no physical means to prevent this

  4. BIOPACK: the ground controlled late access biological research facility.

    PubMed

    van Loon, Jack J W A

    2004-03-01

    Future Space Shuttle flights shall be characterized by activities necessary to further build the International Space Station, ISS. During these missions limited resources are available to conduct biological experiments in space. The Shuttles' Middeck is a very suitable place to conduct science during the ISS assembly missions or dedicated science missions. The BIOPACK, which flew its first mission during the STS-107, provides a versatile Middeck Locker based research tool for gravitational biology studies. The core facility occupies the space of only two Middeck Lockers. Experiment temperatures are controlled for bacteria, plant, invertebrate and mammalian cultures. Gravity levels and profiles can be set ranging from 0 to 2.0 x g on three independent centrifuges. This provides the experimenter with a 1.0 x g on-board reference and intermediate hypogravity and hypergravity data points to investigate e.g. threshold levels in biological responses. Temperature sensitive items can be stored in the facilities' -10 degrees C and +4 degrees C stowage areas. During STS-107 the facility also included a small glovebox (GBX) and passive temperature controlled units (PTCU). The GBX provides the experimenter with two extra levels of containment for safe sample handling. This biological research facility is a late access (L-10 hrs) laboratory, which, when reaching orbit, could automatically be starting up reducing important experiment lag-time and valuable crew time. The system is completely telecommanded when needed. During flight system parameters like temperatures, centrifuge speeds, experiment commanding or sensor readouts can be monitored and changed when needed. Although ISS provides a wide range of research facilities there is still need for an STS-based late access facility such as the BIOPACK providing experimenters with a very versatile research cabinet for biological experiments under microgravity and in-flight control conditions.

  5. Controlled Access under Review: Improving the Governance of Genomic Data Access

    PubMed Central

    Shabani, Mahsa; Dyke, Stephanie O. M.; Joly, Yann; Borry, Pascal

    2015-01-01

    In parallel with massive genomic data production, data sharing practices have rapidly expanded over the last decade. To ensure authorized access to data, access review by data access committees (DACs) has been utilized as one potential solution. Here we discuss core elements to be integrated into the fabric of access review by both established and emerging DACs in order to foster fair, efficient, and responsible access to datasets. We particularly highlight the fact that the access review process could be adversely influenced by the potential conflicts of interest of data producers, particularly when they are directly involved in DACs management. Therefore, in structuring DACs and access procedures, possible data withholding by data producers should receive thorough attention. PMID:26720729

  6. Aeroelastically deflecting flaps for shock/boundary-layer interaction control

    NASA Astrophysics Data System (ADS)

    Gefroh, D.; Loth, E.; Dutton, C.; Hafenrichter, E.

    2003-06-01

    An aeroelastic mesoflap system has been developed to improve the downstream flow properties of an oblique shock/boundary-layer interaction. The mesoflap system employs a set of small flaps over a cavity, whereby the flaps downstream of the interaction bend downward aeroelastically to bleed the flow and the upstream flaps bend upward to re-inject this same mass flow upstream. This recirculating system requires no net mass bleed and therefore has advantages for boundary layer control in external or mixed-compression supersonic aircraft inlets. In addition, the system may be applicable in other aerospace applications where boundary-layer control can help remedy the adverse effects of shock interactions. Several mesoflap systems have been fabricated and examined experimentally to investigate their aerodynamic and structural performance. Each mesoflap is rigidly attached to a spar on its upstream end while the remainder of the flap is free to deflect aeroelastically. The flap length is nominally a few boundary-layer thicknesses in dimension, while the flap thickness is small enough to allow tip deflections that are of the order of the boundary-layer momentum thickness. Experiments were conducted for a Mach 2.41 impinging oblique shock wave interaction with a turbulent boundary layer. Spanwise-centered laser Doppler velocimeter measurements indicate that certain mesoflap designs can show significant flow improvement as compared to the solid-wall case, including increased stagnation pressure recovery and a 7% reduction in boundary layer thickness and sonic thickness. However, one drawback of the mesoflap system is the potential for fatigue, which in some cases led to microcracking followed by flap failure. Structural design improvements to alleviate and avoid this problem included a lower profile spar design, substitution of Nitinol for aluminum as the flap material, and use of stress-relieving holes at the ends of the flap cut-outs.

  7. First Experiences Using XACML for Access Control in Distributed Systems

    NASA Technical Reports Server (NTRS)

    Lorch, Marcus; Proctor, Seth; Lepro, Rebekah; Kafura, Dennis; Shah, Sumit

    2003-01-01

    Authorization systems today are increasingly complex. They span domains of administration, rely on many different authentication sources, and manage permissions that can be as complex as the system itself. Worse still, while there are many standards that define authentication mechanisms, the standards that address authorization are less well defined and tend to work only within homogeneous systems. This paper presents XACML, a standard access control language, as one component of a distributed and inter-operable authorization framework. Several emerging systems which incorporate XACML are discussed. These discussions illustrate how authorization can be deployed in distributed, decentralized systems. Finally, some new and future topics are presented to show where this work is heading and how it will help connect the general components of an authorization system.

  8. Energy management and multi-layer control of networked microgrids

    NASA Astrophysics Data System (ADS)

    Zamora, Ramon

    Networked microgrids is a group of neighboring microgrids that has ability to interchange power when required in order to increase reliability and resiliency. Networked microgrid can operate in different possible configurations including: islanded microgrid, a grid-connected microgrid without a tie-line converter, a grid-connected microgrid with a tie-line converter, and networked microgrids. These possible configurations and specific characteristics of renewable energy offer challenges in designing control and management algorithms for voltage, frequency and power in all possible operating scenarios. In this work, control algorithm is designed based on large-signal model that enables microgrid to operate in wide range of operating points. A combination between PI controller and feed-forward measured system responses will compensate for the changes in operating points. The control architecture developed in this work has multi-layers and the outer layer is slower than the inner layer in time response. The main responsibility of the designed controls are to regulate voltage magnitude and frequency, as well as output power of the DG(s). These local controls also integrate with a microgrid level energy management system or microgrid central controller (MGCC) for power and energy balance for. the entire microgrid in islanded, grid-connected, or networked microgid mode. The MGCC is responsible to coordinate the lower level controls to have reliable and resilient operation. In case of communication network failure, the decentralized energy management will operate locally and will activate droop control. Simulation results indicate the superiority of designed control algorithms compared to existing ones.

  9. Safety systems and access control in the National Ignition Facility.

    PubMed

    Reed, Robert K; Bell, Jayce C

    2013-06-01

    The National Ignition Facility (NIF) is the world's largest and most energetic laser system. The facility has the potential to generate ionizing radiation due to the interaction between the laser beams and target material, with neutrons and gamma rays being produced during deuterium-tritium fusion reactions. To perform these experiments, several types of hazards must be mitigated and controlled to ensure personnel safety. NIF uses a real-time safety system to monitor and mitigate the hazards presented by the facility. The NIF facility Safety Interlock System (SIS) monitors for oxygen deficiency and controls access to the facility preventing exposure to laser light and radiation from the Radiation Generating Devices. It also interfaces to radiation monitoring and other radiological monitoring and alarm systems. The SIS controls permissives to the hazard-generating equipment and annunciates hazard levels in the facility. To do this reliably and safely, the SIS has been designed as a fail-safe system with a proven performance record now spanning over 10 y. This paper discusses the SIS, its design, implementation, operator interfaces, validation/verification, and the hazard mitigation approaches employed in the NIF. A brief discussion of the Failure Modes and Effect Analysis supporting the SIS will also be presented. The paper ends with a general discussion of SIS do's and don'ts and common design flaws that should be avoided in SIS design. PMID:23629061

  10. Persistence Length Control of the Polyelectrolyte Layer-by-Layer Self-Assembly on Carbon Nanotubes

    SciTech Connect

    Huang, S J; Artyukhin, A B; Wang, Y; Ju, J; Stroeve, P; Noy, A

    2005-04-30

    considered only nano-particles with radius 5 nanometer and larger. One-dimensional materials, such as carbon nanotubes, provide an even more interesting template for studying self-assembly mechanisms, since they give us access to even smaller surface curvatures down to 1 nm. We have examined the role of the polymer persistence length in layer-by-layer self-assembly process on carbon nanotubes by observing formation of multilayer polyelectrolyte shells around carbon nanotubes at different ionic strength. Persistence length of polyelectrolytes varies with solution ionic strength, due to screening of the electrostatic repulsion between the polymer Figure 1. TEM images of single-walled carbon nanotubes after polymer deposition for ionic strengths of (A) 0.05M, (B) 0.1M, (C) 0.2M, (D) 0.4M, (E) 0.65M, and (F) 1.05M. Scale bar corresponds to 10 nm. backbone charges; therefore changing ionic strength is a convenient way to alter the configuration of the polymer molecule systematically. We have used the layer-by-layer self-assembly technique to form 5-layer thick coating of the alternating polyallylamine hydrochloride (PAH) and sodium poly(styrenesulfonate) (PSS) layers on the surfaces of the pristine single-wall carbon nanotubes. For our experiments, we grew the nanotubes across copper TEM grid openings using catalytic chemical vapor deposition. The deposition solutions contained different amounts of NaCl to vary the ionic strength. After polymer multilayer formation we examined the resulting coating in high-resolution TEM.

  11. TCP flow control using link layer information in mobile networks

    NASA Astrophysics Data System (ADS)

    Koga, Hiroyuki; Kawahara, Kenji; Oie, Yuji

    2002-07-01

    Mobile Networks have been expanding and IMT-2000 further increases their available bandwidth over wireless links. However, TCP, which is a reliable end-to-end transport protocol, is tuned to perform well in wired networks where bit error rates are very low and packet loss occurs mostly because of congestion. Although a TCP sender can execute flow control to utilize as much available bandwidth as possible in wired networks, it cannot work well in wireless networks characterized by high bit error rates. In the next generation mobile systems, sophisticated error recovery technologies of FEC and ARQ are indeed employed over wireless links, i.e., over Layer 2, to avoid performance degradation of upper layers. However, multiple retransmissions by Layer 2 ARQ can adversely increase transmission delay of TCP segments, which will further make TCP unnecessarily increase RTO (Retransmission TimeOut). Furthermore, a link bandwidth assigned to TCP flows can change in response to changing air conditions to use wireless links efficiently. TCP thus has to adapt its transmission rate according to the changing available bandwidth. The major goal of this study is to develop a receiver-based effective TCP flow control without any modification on TCP senders, which are probably connected with wired networks. For this end, we propose a TCP flow control employing some Layer 2 information on a wireless link at the mobile station. Our performance evaluation of the proposed TCP shows that the receiver-based TCP flow control can moderate the performance degradation very well even if FER on Layer 2 is high.

  12. A Framework for Context Sensitive Risk-Based Access Control in Medical Information Systems.

    PubMed

    Choi, Donghee; Kim, Dohoon; Park, Seog

    2015-01-01

    Since the access control environment has changed and the threat of insider information leakage has come to the fore, studies on risk-based access control models that decide access permissions dynamically have been conducted vigorously. Medical information systems should protect sensitive data such as medical information from insider threat and enable dynamic access control depending on the context such as life-threatening emergencies. In this paper, we suggest an approach and framework for context sensitive risk-based access control suitable for medical information systems. This approach categorizes context information, estimating and applying risk through context- and treatment-based permission profiling and specifications by expanding the eXtensible Access Control Markup Language (XACML) to apply risk. The proposed framework supports quick responses to medical situations and prevents unnecessary insider data access through dynamic access authorization decisions in accordance with the severity of the context and treatment. PMID:26075013

  13. A Framework for Context Sensitive Risk-Based Access Control in Medical Information Systems

    PubMed Central

    Choi, Donghee; Kim, Dohoon; Park, Seog

    2015-01-01

    Since the access control environment has changed and the threat of insider information leakage has come to the fore, studies on risk-based access control models that decide access permissions dynamically have been conducted vigorously. Medical information systems should protect sensitive data such as medical information from insider threat and enable dynamic access control depending on the context such as life-threatening emergencies. In this paper, we suggest an approach and framework for context sensitive risk-based access control suitable for medical information systems. This approach categorizes context information, estimating and applying risk through context- and treatment-based permission profiling and specifications by expanding the eXtensible Access Control Markup Language (XACML) to apply risk. The proposed framework supports quick responses to medical situations and prevents unnecessary insider data access through dynamic access authorization decisions in accordance with the severity of the context and treatment. PMID:26075013

  14. Experiments on the active control of transitional boundary layers

    NASA Astrophysics Data System (ADS)

    Nelson, P. A.; Rioual, J.-L.; Fisher, M. J.

    Experimental results are presented which demonstrate that the streamwise position of the transition region of a flat plate boundary layer can be actively controlled. The means of control is through the application of suction through the surface of the plate, a progressive increase in suction rate being capable of producing transition at progressively larger distances downstream from the plate leading edge. A simple digital feedback regulator based on an integral control law is shown to be most effective in regulating the position of transition, an error signal being derived from measurements of pressure fluctuations on the surface of the plate.

  15. 75 FR 61819 - First Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-06

    ... Federal Aviation Administration First Meeting: RTCA Special Committee 224: Airport Security Access Control... meeting: Airport Security Access Control Systems (Update to DO-230B). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport Security Access...

  16. 77 FR 64838 - Sixteenth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-23

    ... Federal Aviation Administration Sixteenth Meeting: RTCA Special Committee 224, Airport Security Access...). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held November 15,...

  17. 78 FR 16757 - Twentieth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-18

    ... Federal Aviation Administration Twentieth Meeting: RTCA Special Committee 224, Airport Security Access...). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held April 4, 2013 from...

  18. 76 FR 59481 - Ninth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-26

    ... TRANSPORTATION Federal Aviation Administration Ninth Meeting: RTCA Special Committee 224: Airport Security Access... Committee 224 meeting: Airport Security Access Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport Security Access Control...

  19. 77 FR 55894 - Fifteenth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-11

    ... Federal Aviation Administration Fifteenth Meeting: RTCA Special Committee 224, Airport Security Access...). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... Committee 224, Airport Security Access Control Systems DATES: The meeting will be held September 27-28,...

  20. 77 FR 15448 - Twelfth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-15

    ... Federal Aviation Administration Twelfth Meeting: RTCA Special Committee 224, Airport Security Access...). ACTION: Notice of meeting RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... 224, Airport Security Access Control Systems DATES: The meeting will be held April 5, 2012, from 10...

  1. 76 FR 9632 - Fifth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-18

    ... Federal Aviation Administration Fifth Meeting: RTCA Special Committee 224: Airport Security Access Control... meeting: Airport Security Access Control Systems (Update to DO-230B). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport Security Access...

  2. 75 FR 80886 - Third Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-23

    ... Federal Aviation Administration Third Meeting: RTCA Special Committee 224: Airport Security Access Control... meeting: Airport Security Access Control Systems (Update to DO-230B). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport Security Access...

  3. 76 FR 16470 - Sixth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-23

    ... Federal Aviation Administration Sixth Meeting: RTCA Special Committee 224: Airport Security Access Control... meeting: Airport Security Access Control Systems (Update to DO-230B). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport Security Access...

  4. 78 FR 22025 - Twenty First Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-12

    ... Federal Aviation Administration Twenty First Meeting: RTCA Special Committee 224, Airport Security Access...). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held April 9-10,...

  5. 78 FR 43963 - Twenty-Third Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-22

    ... Federal Aviation Administration Twenty-Third Meeting: RTCA Special Committee 224, Airport Security Access...). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held on June 20,...

  6. 77 FR 71474 - Seventeenth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-30

    ... Federal Aviation Administration Seventeenth Meeting: RTCA Special Committee 224, Airport Security Access...). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held December 13,...

  7. 77 FR 2343 - Eleventh Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-17

    ... Federal Aviation Administration Eleventh Meeting: RTCA Special Committee 224, Airport Security Access...). ACTION: Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY: The FAA..., Airport Security Access Control Systems. DATES: The meeting will be held February 9, 2012, from 10...

  8. Dynamic access control model for privacy preserving personalized healthcare in cloud environment.

    PubMed

    Son, Jiseong; Kim, Jeong-Dong; Na, Hong-Seok; Baik, Doo-Kwon

    2015-01-01

    When sharing and storing healthcare data in a cloud environment, access control is a central issue for preserving data privacy as a patient's personal health data may be accessed without permission from many stakeholders. Specifically, dynamic authorization for the access of data is required because personal health data is stored in cloud storage via wearable devices. Therefore, we propose a dynamic access control model for preserving the privacy of personal healthcare data in a cloud environment. The proposed model considers context information for dynamic access. According to the proposed model, access control can be dynamically determined by changing the context information; this means that even for a subject with the same role in the cloud, access permission is defined differently depending on the context information and access condition. Furthermore, we experiment the ability of the proposed model to provide correct responses by representing a dynamic access decision with real-life personalized healthcare system scenarios. PMID:26409546

  9. Dynamic access control model for privacy preserving personalized healthcare in cloud environment.

    PubMed

    Son, Jiseong; Kim, Jeong-Dong; Na, Hong-Seok; Baik, Doo-Kwon

    2015-01-01

    When sharing and storing healthcare data in a cloud environment, access control is a central issue for preserving data privacy as a patient's personal health data may be accessed without permission from many stakeholders. Specifically, dynamic authorization for the access of data is required because personal health data is stored in cloud storage via wearable devices. Therefore, we propose a dynamic access control model for preserving the privacy of personal healthcare data in a cloud environment. The proposed model considers context information for dynamic access. According to the proposed model, access control can be dynamically determined by changing the context information; this means that even for a subject with the same role in the cloud, access permission is defined differently depending on the context information and access condition. Furthermore, we experiment the ability of the proposed model to provide correct responses by representing a dynamic access decision with real-life personalized healthcare system scenarios.

  10. Breaking and Fixing Origin-Based Access Control in Hybrid Web/Mobile Application Frameworks.

    PubMed

    Georgiev, Martin; Jana, Suman; Shmatikov, Vitaly

    2014-02-01

    Hybrid mobile applications (apps) combine the features of Web applications and "native" mobile apps. Like Web applications, they are implemented in portable, platform-independent languages such as HTML and JavaScript. Like native apps, they have direct access to local device resources-file system, location, camera, contacts, etc. Hybrid apps are typically developed using hybrid application frameworks such as PhoneGap. The purpose of the framework is twofold. First, it provides an embedded Web browser (for example, WebView on Android) that executes the app's Web code. Second, it supplies "bridges" that allow Web code to escape the browser and access local resources on the device. We analyze the software stack created by hybrid frameworks and demonstrate that it does not properly compose the access-control policies governing Web code and local code, respectively. Web code is governed by the same origin policy, whereas local code is governed by the access-control policy of the operating system (for example, user-granted permissions in Android). The bridges added by the framework to the browser have the same local access rights as the entire application, but are not correctly protected by the same origin policy. This opens the door to fracking attacks, which allow foreign-origin Web content included into a hybrid app (e.g., ads confined in iframes) to drill through the layers and directly access device resources. Fracking vulnerabilities are generic: they affect all hybrid frameworks, all embedded Web browsers, all bridge mechanisms, and all platforms on which these frameworks are deployed. We study the prevalence of fracking vulnerabilities in free Android apps based on the PhoneGap framework. Each vulnerability exposes sensitive local resources-the ability to read and write contacts list, local files, etc.-to dozens of potentially malicious Web domains. We also analyze the defenses deployed by hybrid frameworks to prevent resource access by foreign-origin Web content

  11. Breaking and Fixing Origin-Based Access Control in Hybrid Web/Mobile Application Frameworks.

    PubMed

    Georgiev, Martin; Jana, Suman; Shmatikov, Vitaly

    2014-02-01

    Hybrid mobile applications (apps) combine the features of Web applications and "native" mobile apps. Like Web applications, they are implemented in portable, platform-independent languages such as HTML and JavaScript. Like native apps, they have direct access to local device resources-file system, location, camera, contacts, etc. Hybrid apps are typically developed using hybrid application frameworks such as PhoneGap. The purpose of the framework is twofold. First, it provides an embedded Web browser (for example, WebView on Android) that executes the app's Web code. Second, it supplies "bridges" that allow Web code to escape the browser and access local resources on the device. We analyze the software stack created by hybrid frameworks and demonstrate that it does not properly compose the access-control policies governing Web code and local code, respectively. Web code is governed by the same origin policy, whereas local code is governed by the access-control policy of the operating system (for example, user-granted permissions in Android). The bridges added by the framework to the browser have the same local access rights as the entire application, but are not correctly protected by the same origin policy. This opens the door to fracking attacks, which allow foreign-origin Web content included into a hybrid app (e.g., ads confined in iframes) to drill through the layers and directly access device resources. Fracking vulnerabilities are generic: they affect all hybrid frameworks, all embedded Web browsers, all bridge mechanisms, and all platforms on which these frameworks are deployed. We study the prevalence of fracking vulnerabilities in free Android apps based on the PhoneGap framework. Each vulnerability exposes sensitive local resources-the ability to read and write contacts list, local files, etc.-to dozens of potentially malicious Web domains. We also analyze the defenses deployed by hybrid frameworks to prevent resource access by foreign-origin Web content

  12. Breaking and Fixing Origin-Based Access Control in Hybrid Web/Mobile Application Frameworks

    PubMed Central

    Georgiev, Martin; Jana, Suman; Shmatikov, Vitaly

    2014-01-01

    Hybrid mobile applications (apps) combine the features of Web applications and “native” mobile apps. Like Web applications, they are implemented in portable, platform-independent languages such as HTML and JavaScript. Like native apps, they have direct access to local device resources—file system, location, camera, contacts, etc. Hybrid apps are typically developed using hybrid application frameworks such as PhoneGap. The purpose of the framework is twofold. First, it provides an embedded Web browser (for example, WebView on Android) that executes the app's Web code. Second, it supplies “bridges” that allow Web code to escape the browser and access local resources on the device. We analyze the software stack created by hybrid frameworks and demonstrate that it does not properly compose the access-control policies governing Web code and local code, respectively. Web code is governed by the same origin policy, whereas local code is governed by the access-control policy of the operating system (for example, user-granted permissions in Android). The bridges added by the framework to the browser have the same local access rights as the entire application, but are not correctly protected by the same origin policy. This opens the door to fracking attacks, which allow foreign-origin Web content included into a hybrid app (e.g., ads confined in iframes) to drill through the layers and directly access device resources. Fracking vulnerabilities are generic: they affect all hybrid frameworks, all embedded Web browsers, all bridge mechanisms, and all platforms on which these frameworks are deployed. We study the prevalence of fracking vulnerabilities in free Android apps based on the PhoneGap framework. Each vulnerability exposes sensitive local resources—the ability to read and write contacts list, local files, etc.—to dozens of potentially malicious Web domains. We also analyze the defenses deployed by hybrid frameworks to prevent resource access by foreign

  13. Arctic layer salinity controls heat loss from deep Atlantic layer in seasonally ice-covered areas of the Barents Sea

    NASA Astrophysics Data System (ADS)

    Lind, Sigrid; Ingvaldsen, Randi B.; Furevik, Tore

    2016-05-01

    In the seasonally ice-covered northern Barents Sea an intermediate layer of cold and relatively fresh Arctic Water at ~25-110 m depth isolates the sea surface and ice cover from a layer of warm and saline Atlantic Water below, a situation that resembles the cold halocline layer in the Eurasian Basin. The upward heat flux from the Atlantic layer is of major concern. What causes variations in the heat flux and how is the Arctic layer maintained? Using observations, we found that interannual variability in Arctic layer salinity determines the heat flux from the Atlantic layer through its control of stratification and vertical mixing. A relatively fresh Arctic layer effectively suppresses the upward heat flux, while a more saline Arctic layer enhances the heat flux. The corresponding upward salt flux causes a positive feedback. The Arctic layer salinity and the water column structures have been remarkably stable during 1970-2011.

  14. Accessibility and ion exchange stoichiometry of ionized carboxylic groups in the active layer of FT30 reverse osmosis membrane.

    PubMed

    Coronell, Orlando; Mariñas, Benito I; Cahill, David G

    2009-07-01

    We have experimentally determined the concentration of Ba2+ that associates with the accessible ionized R-COO- groups in the polyamide active layer of the FT30 reverse osmosis membrane in the pH range 3.42-10.30. Ba2+ concentrations in the active layer ([Ba2+]) were measured using the ion-probing/Rutherford backscattering spectrometry procedure reported in our previous work. We found that at all but the lowest experimental pH 3.42, [Ba2+] was lower than the corresponding total concentrations of R-COO- groups; their difference was consistent with steric and charge effects determining the accessibility and association, respectively, of Ba2+ to R-COO- groups. Accordingly, we propose two descriptors, the accessibility ratio (AR) and the neutralization number (NN), to account for the observed difference. AR, the fraction of R-COO- groups accessible to Ba2+ ions, and NN, the average number of R-COO- groups neutralized per Ba2+ ion, were determined experimentally performing Ag(+)-Ba2+ ion-exchange tests. The resulting AR = 0.40 indicated that on average only 40% of ionizable carboxylic groups were accessible to Ba2+. [Ba2+] values calculated using R-COO- concentrations and the AR and NN concepts were in agreement with experimental [Ba2+] results.

  15. Simulation and optimal control of wind-farm boundary layers

    NASA Astrophysics Data System (ADS)

    Meyers, Johan; Goit, Jay

    2014-05-01

    In large wind farms, the effect of turbine wakes, and their interaction leads to a reduction in farm efficiency, with power generated by turbines in a farm being lower than that of a lone-standing turbine by up to 50%. In very large wind farms or `deep arrays', this efficiency loss is related to interaction of the wind farms with the planetary boundary layer, leading to lower wind speeds at turbine level. Moreover, for these cases it has been demonstrated both in simulations and wind-tunnel experiments that the wind-farm energy extraction is dominated by the vertical turbulent transport of kinetic energy from higher regions in the boundary layer towards the turbine level. In the current study, we investigate the use of optimal control techniques combined with Large-Eddy Simulations (LES) of wind-farm boundary layer interaction for the increase of total energy extraction in very large `infinite' wind farms. We consider the individual wind turbines as flow actuators, whose energy extraction can be dynamically regulated in time so as to optimally influence the turbulent flow field, maximizing the wind farm power. For the simulation of wind-farm boundary layers we use large-eddy simulations in combination with actuator-disk and actuator-line representations of wind turbines. Simulations are performed in our in-house pseudo-spectral code SP-Wind that combines Fourier-spectral discretization in horizontal directions with a fourth-order finite-volume approach in the vertical direction. For the optimal control study, we consider the dynamic control of turbine-thrust coefficients in an actuator-disk model. They represent the effect of turbine blades that can actively pitch in time, changing the lift- and drag coefficients of the turbine blades. Optimal model-predictive control (or optimal receding horizon control) is used, where the model simply consists of the full LES equations, and the time horizon is approximately 280 seconds. The optimization is performed using a

  16. Boundary-layer-ingesting inlet flow control system

    NASA Technical Reports Server (NTRS)

    Owens, Lewis R. (Inventor); Allan, Brian G. (Inventor)

    2010-01-01

    A system for reducing distortion at the aerodynamic interface plane of a boundary-layer-ingesting inlet using a combination of active and passive flow control devices is disclosed. Active flow control jets and vortex generating vanes are used in combination to reduce distortion across a range of inlet operating conditions. Together, the vortex generating vanes can reduce most of the inlet distortion and the active flow control jets can be used at a significantly reduced control jet mass flow rate to make sure the inlet distortion stays low as the inlet mass flow rate varies. Overall inlet distortion, measured and described as average SAE circumferential distortion descriptor, was maintained at a value of 0.02 or less. Advantageous arrangements and orientations of the active flow control jets and the vortex generating vanes were developed using computational fluid dynamics simulations and wind tunnel experimentations.

  17. [Co/Ni]-CoFeB hybrid free layer stack materials for high density magnetic random access memory applications

    NASA Astrophysics Data System (ADS)

    Liu, E.; Swerts, J.; Couet, S.; Mertens, S.; Tomczak, Y.; Lin, T.; Spampinato, V.; Franquet, A.; Van Elshocht, S.; Kar, G.; Furnemont, A.; De Boeck, J.

    2016-03-01

    Alternative free layer materials with high perpendicular anisotropy are researched to provide spin-transfer-torque magnetic random access memory stacks' sufficient thermal stability at critical dimensions of 20 nm and below. We demonstrate a high tunnel magetoresistance (TMR) MgO-based magnetic tunnel junction stack with a hybrid free layer design made of a [Co/Ni] multilayer and CoFeB. The seed material on which the [Co/Ni] multilayer is deposited determines its switching characteristics. When deposited on a Pt seed layer, soft magnetic switching behavior with high squareness is obtained. When deposited on a NiCr seed, the perpendicular anisotropy remains high, but the squareness is low and coercivity exceeds 1000 Oe. Interdiffusion of the seed material with the [Co/Ni] multilayers is found to be responsible for the different switching characteristics. In optimized stacks, a TMR of 165% and low resistance-area (RA) product of 7.0 Ω μm2 are attained for free layers with an effective perpendicular magnetic anisotropy energy of 1.25 erg/cm2, which suggests that the hybrid free layer materials may be a viable candidate for high density magnetic random access memory applications.

  18. Boundary Layer Control by Means of Plasma Actuators

    SciTech Connect

    Quadros, R.

    2007-09-06

    The development of controlled transition in a flat-plate boundary layer is investigated using Large Eddy Simulations (LES) with the dynamic Smagorinsky model. The analysis of flow control with the objective to optimize the effects of Tollmien-Schlichting waves on a flat plate by means of plasma actuators was studied. The plasma effect is modeled as a body force in the momentum equations. These equations are solved in a uniform grid using a 2nd-order finite difference scheme in time and space. The response of plasma actuators operating in different time-dependent conditions, produced by transient or periodic inputs at different frequencies, is also analyzed.

  19. Numerical simulation of transition control in boundary layers

    NASA Astrophysics Data System (ADS)

    Laurien, E.; Kleiser, L.

    The transition process from laminar to turbulent boundary layers is simulated by numerical integration of the 3D incompressible Navier-Stokes equations. Spatially periodic wave disturbances in a parallel Blasius flow are assumed. A spectral method with real-space Chebyshev collocation in the normal direction is employed. Both the classical K-type and the subharmonic type of transition are investigated. Good agreement with measurements and flow visualizations of transition experiments is obtained. Control of transition by wave superposition is simulated using periodic wall suction/blowing. It is shown that 2D control works well at an early stage but fails after significant 3D disturbances have developed.

  20. Bureau of Prisons access control system: functional and operational requirements

    NASA Astrophysics Data System (ADS)

    Janus, Michael; Carlson, Peter M.; Kane, Thomas

    1997-01-01

    The Federal Bureau of Prisons (BOP) operates 86 correctional institutions nationwide. The BOP has grown dramatically, the size of its inmate population growing from just over 41,000 inmates in 1987 to over 100,000 today. The number of BOP staff managing these facilities has grown correspondingly, more than doubling in number in the same ten year period. Technology has paid a major role in keeping up with this growth while maintaining high standards of security in BOP institutions. In an attempt to further enhance security in its institutions, the BOP has recently begun pilot testing an access control and entry system (ACES). ACES is intended to provide an automated record of very entry and exit to a correctional institution. ACES takes advantage of several methods of identifying an individual (inmate, staff or visitor) to assure that the individual exiting the institution is the same as the individual entering. The pilot test has raised a number of questions regarding the implementation of a technologically sophisticated system in a correctional institution. Questions of training, support, 'ownership,' cost effectiveness, and future potential all influence the deployment of this system. Preliminary results indicate that an adequate training and support system is essential to the performance of any sophisticated system and that other organizational issues need to be addressed before the decision to implement is made.

  1. 33 CFR 104.265 - Security measures for access control.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... security measures to: (1) Deter the unauthorized introduction of dangerous substances and devices... approved VSP. These additional security measures may include: (1) Increasing the frequency and detail of... operations to deter unauthorized access; (4) Limiting the number of access points to the vessel by...

  2. 33 CFR 104.265 - Security measures for access control.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... security measures to: (1) Deter the unauthorized introduction of dangerous substances and devices... approved VSP. These additional security measures may include: (1) Increasing the frequency and detail of... operations to deter unauthorized access; (4) Limiting the number of access points to the vessel by...

  3. The role of the inserted layer in resistive random access memory device

    NASA Astrophysics Data System (ADS)

    Zhang, Dainan; Ma, Guokun; Zhang, Huaiwu; Tang, Xiaoli; Zhong, Zhiyong; Jie, Li; Su, Hua

    2016-07-01

    NiO resistive switching devices were fabricated by reactive DC magnetron sputtering at room temperature containing different inserted layers. From measurements, we demonstrated the filaments were made up by metal Co rather than the oxygen defect or other metal. A current jumping phenomenon in the SET process was observed, evidencing that the filament generating procedure was changed due to the inserted layers. In this process, we demonstrate the current jumping appeared in higher voltage region when the position of inserted layer was close to the bottom electrode. The I-V curves shifted to the positive direction as the thickness of inserted layer increasing. With the change of the number of inserted layers, SET voltages varied while the RESET voltage kept stable. According to the electrochemical metallization memory mechanism, detailed explanations on all the phenomena were addressed. This discovery is supposed of great potentials in the use of designing multi-layer RRAM devices.

  4. Dynamic Control of Optical Response in Layered Metal Chalcogenide Nanoplates.

    PubMed

    Liu, Yanping; Tom, Kyle; Wang, Xi; Huang, Chunming; Yuan, Hongtao; Ding, Hong; Ko, Changhyun; Suh, Joonki; Pan, Lawrence; Persson, Kristin A; Yao, Jie

    2016-01-13

    Tunable optical transitions in ultrathin layered 2-dimensional (2D) materials unveil the electronic structures of materials and provide exciting prospects for potential applications in optics and photonics. Here, we present our realization of dynamic optical modulation of layered metal chalcogenide nanoplates using ionic liquid (IL) gating over a wide spectral range. The IL gating significantly increased the tuning range of the Fermi level and, as a result, substantially altered the optical transitions in the nanoplates. Using heavily n-doped Bi2Se3 nanoplates, we substantially modulated the light transmission through the ultrathin layer. A tunable, high-transmission spectral window in the visible to near-infrared region has been observed due to simultaneous shifts of both the plasma edge and absorption edge of the material. On the other hand, optical response of multilayer MoSe2 flakes gated by IL has shown enhanced transmission in both positive and negative biases, which is consistent with their ambipolar electrical behavior. The electrically controlled optical property tuning in metal chalcogenide material systems provides new opportunities for potential applications, such as wide spectral range optical modulators, optical filters, and electrically controlled smart windows with extremely low material consumption.

  5. Dynamic Control of Optical Response in Layered Metal Chalcogenide Nanoplates.

    PubMed

    Liu, Yanping; Tom, Kyle; Wang, Xi; Huang, Chunming; Yuan, Hongtao; Ding, Hong; Ko, Changhyun; Suh, Joonki; Pan, Lawrence; Persson, Kristin A; Yao, Jie

    2016-01-13

    Tunable optical transitions in ultrathin layered 2-dimensional (2D) materials unveil the electronic structures of materials and provide exciting prospects for potential applications in optics and photonics. Here, we present our realization of dynamic optical modulation of layered metal chalcogenide nanoplates using ionic liquid (IL) gating over a wide spectral range. The IL gating significantly increased the tuning range of the Fermi level and, as a result, substantially altered the optical transitions in the nanoplates. Using heavily n-doped Bi2Se3 nanoplates, we substantially modulated the light transmission through the ultrathin layer. A tunable, high-transmission spectral window in the visible to near-infrared region has been observed due to simultaneous shifts of both the plasma edge and absorption edge of the material. On the other hand, optical response of multilayer MoSe2 flakes gated by IL has shown enhanced transmission in both positive and negative biases, which is consistent with their ambipolar electrical behavior. The electrically controlled optical property tuning in metal chalcogenide material systems provides new opportunities for potential applications, such as wide spectral range optical modulators, optical filters, and electrically controlled smart windows with extremely low material consumption. PMID:26599063

  6. Possibilities for drag reduction by boundary layer control

    NASA Technical Reports Server (NTRS)

    Naiman, I.

    1946-01-01

    The mechanics of laminar boundary layer transition are reviewed. Drag possibilities for boundary layer control are analyzed using assumed conditions of transition Reynolds number, inlet loss, number of slots, blower efficiency, and duct losses. Although the results of such analysis are highly favorable, those obtained by experimental investigations yield conflicting results, showing only small gains, and sometimes losses. Reduction of this data indicates that there is a lower limit to the quantity of air which must be removed at the slot in order to stabilize the laminar flow. The removal of insufficient air permits transition to occur while the removal of excessive amounts of air results in high power costs, with a net drag increases. With the estimated value of flow coefficient and duct losses equal to half the dynamic pressure, drag reductions of 50% may be obtained; with twice this flow coefficient, the drag saving is reduced to 25%.

  7. 78 FR 31627 - Twenty-Second Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-24

    ... Control Systems AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held on June 20,...

  8. 78 FR 7850 - Nineteenth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-04

    ... Control Systems AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems. SUMMARY... Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held February 21,...

  9. 10 CFR 20.1602 - Control of access to very high radiation areas.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Control of access to very high radiation areas. 20.1602 Section 20.1602 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1602 Control of access to very high radiation...

  10. 10 CFR 20.1602 - Control of access to very high radiation areas.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Control of access to very high radiation areas. 20.1602 Section 20.1602 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1602 Control of access to very high radiation...

  11. 10 CFR 20.1602 - Control of access to very high radiation areas.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Control of access to very high radiation areas. 20.1602 Section 20.1602 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1602 Control of access to very high radiation...

  12. 10 CFR 20.1601 - Control of access to high radiation areas.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Control of access to high radiation areas. 20.1601 Section 20.1601 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1601 Control of access to high radiation areas....

  13. 10 CFR 20.1601 - Control of access to high radiation areas.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Control of access to high radiation areas. 20.1601 Section 20.1601 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1601 Control of access to high radiation areas....

  14. 10 CFR 20.1602 - Control of access to very high radiation areas.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Control of access to very high radiation areas. 20.1602 Section 20.1602 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1602 Control of access to very high radiation...

  15. 10 CFR 20.1602 - Control of access to very high radiation areas.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Control of access to very high radiation areas. 20.1602 Section 20.1602 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1602 Control of access to very high radiation...

  16. 10 CFR 20.1601 - Control of access to high radiation areas.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Control of access to high radiation areas. 20.1601 Section 20.1601 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1601 Control of access to high radiation areas....

  17. 10 CFR 20.1601 - Control of access to high radiation areas.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Control of access to high radiation areas. 20.1601 Section 20.1601 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1601 Control of access to high radiation areas....

  18. 10 CFR 20.1601 - Control of access to high radiation areas.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Control of access to high radiation areas. 20.1601 Section 20.1601 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Control of Exposure From External Sources in Restricted Areas § 20.1601 Control of access to high radiation areas....

  19. 21 CFR 1311.130 - Requirements for establishing logical access control-Institutional practitioner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Requirements for establishing logical access...) Electronic Prescriptions § 1311.130 Requirements for establishing logical access control—Institutional... practitioner that enters permissions for logical access controls into the application. The...

  20. 21 CFR 1311.125 - Requirements for establishing logical access control-Individual practitioner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Requirements for establishing logical access... Prescriptions § 1311.125 Requirements for establishing logical access control—Individual practitioner. (a) At... his two-factor authentication credential to satisfy the logical access controls. The second...

  1. Broadband passive optical network media access control protocols

    NASA Astrophysics Data System (ADS)

    Quayle, Alan

    1996-11-01

    Most telecommunication operators are currently deciding on how to respond to customers' needs stimulated by the synergy between compression coding of multimedia and the emergence of broadband digital networks. This paper describes a range of broadband access architectures under consideration in the full services access network initiative. All architectures have a common requirement for a broadband ATM PON. A common broadband PON applicable to many operators increases the world-wide market for the product. With greater production volumes manufacturers' costs reduce because of the experience curve effect making broadband access systems economic.

  2. Role-based access control through on-demand classification of electronic health record.

    PubMed

    Tiwari, Basant; Kumar, Abhay

    2015-01-01

    Electronic health records (EHR) provides convenient method to exchange medical information of patients between different healthcare providers. Access control mechanism in healthcare services characterises authorising users to access EHR records. Role Based Access Control helps to restrict EHRs to users in a certain role. Significant works have been carried out for access control since last one decade but little emphasis has been given to on-demand role based access control. Presented work achieved access control through physical data isolation which is more robust and secure. We propose an algorithm in which selective combination of policies for each user of the EHR database has been defined. We extend well known data mining technique 'classification' to group EHRs with respect to the given role. Algorithm works by taking various roles as class and defined their features as a vector. Here, features are used as a Feature Vector for classification to describe user authority. PMID:26559071

  3. Role-based access control through on-demand classification of electronic health record.

    PubMed

    Tiwari, Basant; Kumar, Abhay

    2015-01-01

    Electronic health records (EHR) provides convenient method to exchange medical information of patients between different healthcare providers. Access control mechanism in healthcare services characterises authorising users to access EHR records. Role Based Access Control helps to restrict EHRs to users in a certain role. Significant works have been carried out for access control since last one decade but little emphasis has been given to on-demand role based access control. Presented work achieved access control through physical data isolation which is more robust and secure. We propose an algorithm in which selective combination of policies for each user of the EHR database has been defined. We extend well known data mining technique 'classification' to group EHRs with respect to the given role. Algorithm works by taking various roles as class and defined their features as a vector. Here, features are used as a Feature Vector for classification to describe user authority.

  4. Control of Thermal Convection in Layered Fluids Using Magnetic fields

    NASA Technical Reports Server (NTRS)

    Ramachandran, N.; Leslie, F. W.

    2003-01-01

    Immiscible fluid layers are found in a host of applications ranging from materials processing, for example the use of encapsulants in float zone crystal growth technique and a buffer layer in industrial Czochralski growth of crystals to prevent Marangoni convection, to heat transfer phenomena in day-to-day processes like the presence of air pockets in heat exchangers. In the microgravity and space processing realm, the exploration of other planets requires the development of enabling technologies in several fronts. The reduction in the gravity level poses unique challenges for fluid handling and heat transfer applications. The present work investigates the efficacy of controlling thermal convective flow using magnetic fluids and magnetic fields. The setup is a two-layer immiscible liquids system with one of the fluids being a diluted ferrofluid (super paramagnetic nano particles dispersed in carrier fluid). Using an external magnetic field one can essentially dial in a volumetric force - gravity level, on the magnetic fluid and thereby affect the system thermo-fluid behavior. The paper will describe the experimental and numerical modeling approach to the problem and discuss results obtained to date.

  5. Active Flow Control on a Boundary-Layer-Ingesting Inlet

    NASA Technical Reports Server (NTRS)

    Gorton, Susan Althoff; Owens, Lewis R.; Jenkins, Luther N.; Allan, Brian G.; Schuster, Ernest P.

    2004-01-01

    Boundary layer ingestion (BLI) is explored as means to improve overall system performance for Blended Wing Body configuration. The benefits of BLI for vehicle system performance benefit are assessed with a process derived from first principles suitable for highly-integrated propulsion systems. This performance evaluation process provides framework within which to assess the benefits of an integrated BLI inlet and lays the groundwork for higher-fidelity systems studies. The results of the system study show that BLI provides a significant improvement in vehicle performance if the inlet distortion can be controlled, thus encouraging the pursuit of active flow control (AFC) as a BLI enabling technology. The effectiveness of active flow control in reducing engine inlet distortion was assessed using a 6% scale model of a 30% BLI offset, diffusing inlet. The experiment was conducted in the NASA Langley Basic Aerodynamics Research Tunnel with a model inlet designed specifically for this type of testing. High mass flow pulsing actuators provided the active flow control. Measurements were made of the onset boundary layer, the duct surface static pressures, and the mass flow through the duct and the actuators. The distortion was determined by 120 total pressure measurements located at the aerodynamic interface plane. The test matrix was limited to a maximum freestream Mach number of 0.15 with scaled mass flows through the inlet for that condition. The data show that the pulsed actuation can reduce distortion from 29% to 4.6% as measured by the circumferential distortion descriptor DC60 using less than 1% of inlet mass flow. Closed loop control of the actuation was also demonstrated using a sidewall surface static pressure as the response sensor.

  6. Tandem Solar Cells from Accessible Low Band-Gap Polymers Using an Efficient Interconnecting Layer.

    PubMed

    Bag, Santanu; Patel, Romesh J; Bunha, Ajaykumar; Grand, Caroline; Berrigan, J Daniel; Dalton, Matthew J; Leever, Benjamin J; Reynolds, John R; Durstock, Michael F

    2016-01-13

    Tandem solar cell architectures are designed to improve device photoresponse by enabling the capture of wider range of solar spectrum as compared to single-junction device. However, the practical realization of this concept in bulk-heterojunction polymer systems requires the judicious design of a transparent interconnecting layer compatible with both polymers. Moreover, the polymers selected should be readily synthesized at large scale (>1 kg) and high performance. In this work, we demonstrate a novel tandem polymer solar cell that combines low band gap poly isoindigo [P(T3-iI)-2], which is easily synthesized in kilogram quantities, with a novel Cr/MoO3 interconnecting layer. Cr/MoO3 is shown to be greater than 80% transparent above 375 nm and an efficient interconnecting layer for P(T3-iI)-2 and PCDTBT, leading to 6% power conversion efficiencies under AM 1.5G illumination. These results serve to extend the range of interconnecting layer materials for tandem cell fabrication by establishing, for the first time, that a thin, evaporated layer of Cr/MoO3 can work as an effective interconnecting layer in a tandem polymer solar cells made with scalable photoactive materials.

  7. Tandem Solar Cells from Accessible Low Band-Gap Polymers Using an Efficient Interconnecting Layer.

    PubMed

    Bag, Santanu; Patel, Romesh J; Bunha, Ajaykumar; Grand, Caroline; Berrigan, J Daniel; Dalton, Matthew J; Leever, Benjamin J; Reynolds, John R; Durstock, Michael F

    2016-01-13

    Tandem solar cell architectures are designed to improve device photoresponse by enabling the capture of wider range of solar spectrum as compared to single-junction device. However, the practical realization of this concept in bulk-heterojunction polymer systems requires the judicious design of a transparent interconnecting layer compatible with both polymers. Moreover, the polymers selected should be readily synthesized at large scale (>1 kg) and high performance. In this work, we demonstrate a novel tandem polymer solar cell that combines low band gap poly isoindigo [P(T3-iI)-2], which is easily synthesized in kilogram quantities, with a novel Cr/MoO3 interconnecting layer. Cr/MoO3 is shown to be greater than 80% transparent above 375 nm and an efficient interconnecting layer for P(T3-iI)-2 and PCDTBT, leading to 6% power conversion efficiencies under AM 1.5G illumination. These results serve to extend the range of interconnecting layer materials for tandem cell fabrication by establishing, for the first time, that a thin, evaporated layer of Cr/MoO3 can work as an effective interconnecting layer in a tandem polymer solar cells made with scalable photoactive materials. PMID:26699653

  8. A Quality of Context-Aware Approach to Access Control in Pervasive Environments

    NASA Astrophysics Data System (ADS)

    Toninelli, Alessandra; Corradi, Antonio; Montanari, Rebecca

    The widespread diffusion of wireless-enabled portable devices creates novel opportunities for users to share resources anywhere and anytime, but makes access control a crucial issue. User/device mobility and heterogeneity, together with network topology and conditions variability, complicate access control and call for novel solutions to dynamically adapt access decisions to the different operating conditions. Several research efforts have emerged in recent years that propose to exploit context-awareness to control access to resources based on context visibility and changes. Context-based access control requires, however, to take into account the quality of context information used to drive access decisions (QoC). Quality of context has in fact a profound impact on the correct behavior of any context-aware access control framework. Using context information with insufficient quality might increase the risk of incorrect access control decisions, thus leading to dangerous security breaches in resource sharing. In this paper we propose a QoC-aware approach to access control for anywhere, anytime resource sharing. The paper describes the design, implementation and evaluation of the Proteus policy framework, which combines two design guidelines to enable dynamic adaptation of policies depending on context changes: context-awareness with QoC guarantees and semantic technologies to allow high-level description of context/policy specification and reasoning about context/policies.

  9. A Parallel Controls Software Approach for PEP II: AIDA & Matlab Middle Layer

    SciTech Connect

    Wittmer, W.; Colocho, W.; White, G.; /SLAC

    2007-11-06

    The controls software in use at PEP II (Stanford Control Program - SCP) had originally been developed in the eighties. It is very successful in routine operation but due to its internal structure it is difficult and time consuming to extend its functionality. This is problematic during machine development and when solving operational issues. Routinely, data has to be exported from the system, analyzed offline, and calculated settings have to be reimported. Since this is a manual process, it is time consuming and error-prone. Setting up automated processes, as is done for MIA (Model Independent Analysis), is also time consuming and specific to each application. Recently, there has been a trend at light sources to use MATLAB as the platform to control accelerators using a 'MATLAB Middle Layer' (MML), and so called channel access (CA) programs to communicate with the low level control system (LLCS). This has proven very successful, especially during machine development time and trouble shooting. A special CA code, named AIDA (Accelerator Independent Data Access), was developed to handle the communication between MATLAB, modern software frameworks, and the SCP. The MML had to be adapted for implementation at PEP II. Colliders differ significantly in their designs compared to light sources, which poses a challenge. PEP II is the first collider at which this implementation is being done. We will report on this effort, which is still ongoing.

  10. An effective access control approach to support mobility in IPv6 networks

    NASA Astrophysics Data System (ADS)

    Peng, Xue-hai; Lin, Chuang

    2005-11-01

    Access control is an important method to improve network security and prevent protected resources from being used by some nodes without authority. Moreover, mobility is an important trend of internet. In this paper, based on the architecture of hierarchical mobile IPv6, we proposed an effective access control approach to support mobility in IPv6 networks, which can ensure the operation of access control when a mobile node roams in these domains with different polices, with decreased delay of access negotiation and cost of delivering messages.

  11. Controlled Fabrication of Nanoporous Oxide Layers on Zircaloy by Anodization

    NASA Astrophysics Data System (ADS)

    Park, Yang Jeong; Ha, Jun Mok; Ali, Ghafar; Kim, Hyun Jin; Addad, Yacine; Cho, Sung Oh

    2015-09-01

    We have presented a mechanism to explain why the resulting oxide morphology becomes a porous or a tubular nanostructure when a zircaloy is electrochemically anodized. A porous zirconium oxide nanostructure is always formed at an initial anodization stage, but the degree of interpore dissolution determines whether the final morphology is nanoporous or nanotubular. The interpore dissolution rate can be tuned by changing the anodization parameters such as anodization time and water content in an electrolyte. Consequently, porous or tubular oxide nanostructures can be selectively fabricated on a zircaloy surface by controlling the parameters. Based on this mechanism, zirconium oxide layers with completely nanoporous, completely nanotubular, and intermediate morphologies between a nanoporous and a nanotubular structure were controllably fabricated.

  12. 76 FR 50811 - Eighth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-16

    ... TRANSPORTATION Federal Aviation Administration Eighth Meeting: RTCA Special Committee 224: Airport Security... Committee 224 meeting: Airport Security Access Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport Security Access Control...

  13. 78 FR 51810 - Twenty-Fourth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-21

    ... Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control... RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held on... TRANSPORTATION Federal Aviation Administration Twenty-Fourth Meeting: RTCA Special Committee 224,...

  14. 77 FR 25525 - Thirteenth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-30

    ... TRANSPORTATION Federal Aviation Administration Thirteenth Meeting: RTCA Special Committee 224, Airport Security... (DOT). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security Access Control Systems... Committee 224, Airport Security Access Control Systems DATES: The meeting will be held May 30, 2012, from...

  15. Perspectives on open access high resolution digital elevation models to produce global flood hazard layers

    NASA Astrophysics Data System (ADS)

    Sampson, Christopher; Smith, Andrew; Bates, Paul; Neal, Jeffrey; Trigg, Mark

    2015-12-01

    Global flood hazard models have recently become a reality thanks to the release of open access global digital elevation models, the development of simplified and highly efficient flow algorithms, and the steady increase in computational power. In this commentary we argue that although the availability of open access global terrain data has been critical in enabling the development of such models, the relatively poor resolution and precision of these data now limit significantly our ability to estimate flood inundation and risk for the majority of the planet's surface. The difficulty of deriving an accurate 'bare-earth' terrain model due to the interaction of vegetation and urban structures with the satellite-based remote sensors means that global terrain data are often poorest in the areas where people, property (and thus vulnerability) are most concentrated. Furthermore, the current generation of open access global terrain models are over a decade old and many large floodplains, particularly those in developing countries, have undergone significant change in this time. There is therefore a pressing need for a new generation of high resolution and high vertical precision open access global digital elevation models to allow significantly improved global flood hazard models to be developed.

  16. 33 CFR 105.255 - Security measures for access control.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... security measures to: (1) Deter the unauthorized introduction of dangerous substances and devices... unescorted access to secure areas for a period of no longer than 7 consecutive calendar days if: (i) The... paragraph (d) of this section. (5) Deny or revoke a person's authorization to be on the facility if...

  17. 33 CFR 105.255 - Security measures for access control.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... security measures to: (1) Deter the unauthorized introduction of dangerous substances and devices... unescorted access to secure areas for a period of no longer than 7 consecutive calendar days if: (i) The... paragraph (d) of this section. (5) Deny or revoke a person's authorization to be on the facility if...

  18. Laser controlled by a multiple-layer heterostructure

    SciTech Connect

    Chemla, D.S.; Miller, D.A.B.; Smith, P.W.

    1989-08-22

    This paper describes a semiconductor device. The device comprising: first layers of material having a nonlinear optical absorption at a predetermined optical frequency; characterized by second layers of material alternated with the first layers, and the spacing of the first layers being an integer multiple of one-half the wavelength of light of the predetermined optical frequency.

  19. A dynamic access control method based on QoS requirement

    NASA Astrophysics Data System (ADS)

    Li, Chunquan; Wang, Yanwei; Yang, Baoye; Hu, Chunyang

    2013-03-01

    A dynamic access control method is put forward to ensure the security of the sharing service in Cloud Manufacturing, according to the application characteristics of cloud manufacturing collaborative task. The role-based access control (RBAC) model is extended according to the characteristics of cloud manufacturing in this method. The constraints are considered, which are from QoS requirement of the task context to access control, based on the traditional static authorization. The fuzzy policy rules are established about the weighted interval value of permissions. The access control authorities of executable service by users are dynamically adjusted through the fuzzy reasoning based on the QoS requirement of task. The main elements of the model are described. The fuzzy reasoning algorithm of weighted interval value based QoS requirement is studied. An effective method is provided to resolve the access control of cloud manufacturing.

  20. Secure Remote Access Issues in a Control Center Environment

    NASA Technical Reports Server (NTRS)

    Pitts, Lee; McNair, Ann R. (Technical Monitor)

    2002-01-01

    The ISS finally reached an operational state and exists for local and remote users. Onboard payload systems are managed by the Huntsville Operations Support Center (HOSC). Users access HOSC systems by internet protocols in support of daily operations, preflight simulation, and test. In support of this diverse user community, a modem security architecture has been implemented. The architecture has evolved over time from an isolated but open system to a system which supports local and remote access to the ISS over broad geographic regions. This has been accomplished through the use of an evolved security strategy, PKI, and custom design. Through this paper, descriptions of the migration process and the lessons learned are presented. This will include product decision criteria, rationale, and the use of commodity products in the end architecture. This paper will also stress the need for interoperability of various products and the effects of seemingly insignificant details.

  1. Controlled sound field with a dual layer loudspeaker array

    NASA Astrophysics Data System (ADS)

    Shin, Mincheol; Fazi, Filippo M.; Nelson, Philip A.; Hirono, Fabio C.

    2014-08-01

    Controlled sound interference has been extensively investigated using a prototype dual layer loudspeaker array comprised of 16 loudspeakers. Results are presented for measures of array performance such as input signal power, directivity of sound radiation and accuracy of sound reproduction resulting from the application of conventional control methods such as minimization of error in mean squared pressure, maximization of energy difference and minimization of weighted pressure error and energy. Procedures for selecting the tuning parameters have also been introduced. With these conventional concepts aimed at the production of acoustically bright and dark zones, all the control methods used require a trade-off between radiation directivity and reproduction accuracy in the bright zone. An alternative solution is proposed which can achieve better performance based on the measures presented simultaneously by inserting a low priority zone named as the “gray” zone. This involves the weighted minimization of mean-squared errors in both bright and dark zones together with the gray zone in which the minimization error is given less importance. This results in the production of directional bright zone in which the accuracy of sound reproduction is maintained with less required input power. The results of simulations and experiments are shown to be in excellent agreement.

  2. Predetermined control of turbulent boundary layer with a piezoelectric oscillator

    NASA Astrophysics Data System (ADS)

    Xiao-Bo, Zheng; Nan, Jiang; Hao, Zhang

    2016-01-01

    With a piezoelectric (PZT) oscillator, the predetermined controls of the turbulent boundary layer (TBL) are effective in reducing the drag force. The stream-wise velocities in the TBL are accurately measured downstream of the oscillator driven by an adjustable power source. The mean velocity profiles in the inner and outer scales are reported and the skin friction stresses with different voltage parameters are compared. Reduction of integral spatial scales in the inner region below y+ of 30 suggests that the oscillator at work breaks up the near-wall stream-wise vortices responsible for high skin friction. For the TBL at Reθ of 2183, the controls with a frequency of 160 Hz are superior among our experiments and a relative drag reduction rate of 26.83% is exciting. Wavelet analyses provide a reason why the controls with this special frequency perform best. Project supported by the National Natural Science Foundation of China (Grant Nos. 11332006, 11272233, and 11411130150) and the National Basic Research Program of China (Grant Nos. 2012CB720101 and 2012CB720103).

  3. Proximity-based access control for context-sensitive information provision in SOA-based systems

    NASA Astrophysics Data System (ADS)

    Rajappan, Gowri; Wang, Xiaofei; Grant, Robert; Paulini, Matthew

    2014-06-01

    Service Oriented Architecture (SOA) has enabled open-architecture integration of applications within an enterprise. For net-centric Command and Control (C2), this elucidates information sharing between applications and users, a critical requirement for mission success. The Information Technology (IT) access control schemes, which arbitrate who gets access to what information, do not yet have the contextual knowledge to dynamically allow this information sharing to happen dynamically. The access control might prevent legitimate users from accessing information relevant to the current mission context, since this context may be very different from the context for which the access privileges were configured. We evaluate a pair of data relevance measures - proximity and risk - and use these as the basis of dynamic access control. Proximity is a measure of the strength of connection between the user and the resource. However, proximity is not sufficient, since some data might have a negative impact, if leaked, which far outweighs importance to the subject's mission. For this, we use a risk measure to quantify the downside of data compromise. Given these contextual measures of proximity and risk, we investigate extending Attribute-Based Access Control (ABAC), which is used by the Department of Defense, and Role-Based Access Control (RBAC), which is widely used in the civilian market, so that these standards-based access control models are given contextual knowledge to enable dynamic information sharing. Furthermore, we consider the use of such a contextual access control scheme in a SOA-based environment, in particular for net-centric C2.

  4. High-performance bilayer flexible resistive random access memory based on low-temperature thermal atomic layer deposition

    PubMed Central

    2013-01-01

    We demonstrated a flexible resistive random access memory device through a low-temperature atomic layer deposition process. The device is composed of an HfO2/Al2O3-based functional stack on an indium tin oxide-coated polyethylene terephthalate substrate. After the initial reset operation, the device exhibits a typical bipolar, reliable, and reproducible resistive switching behavior. After a 104-s retention time, the memory window of the device is still in accordance with excellent thermal stability, and a 10-year usage is still possible with the resistance ratio larger than 10 at room temperature and at 85°C. In addition, the operation speed of the device was estimated to be 500 ns for the reset operation and 800 ns for the set operation, which is fast enough for the usage of the memories in flexible circuits. Considering the excellent performance of the device fabricated by low-temperature atomic layer deposition, the process may promote the potential applications of oxide-based resistive random access memory in flexible integrated circuits. PMID:23421424

  5. Analyzing the effect of routing protocols on media access control protocols in radio networks

    SciTech Connect

    Barrett, C. L.; Drozda, M.; Marathe, A.; Marathe, M. V.

    2002-01-01

    We study the effect of routing protocols on the performance of media access control (MAC) protocols in wireless radio networks. Three well known MAC protocols: 802.11, CSMA, and MACA are considered. Similarly three recently proposed routing protocols: AODV, DSR and LAR scheme 1 are considered. The experimental analysis was carried out using GloMoSim: a tool for simulating wireless networks. The main focus of our experiments was to study how the routing protocols affect the performance of the MAC protocols when the underlying network and traffic parameters are varied. The performance of the protocols was measured w.r.t. five important parameters: (i) number of received packets, (ii) average latency of each packet, (iii) throughput (iv) long term fairness and (v) number of control packets at the MAC layer level. Our results show that combinations of routing and MAC protocols yield varying performance under varying network topology and traffic situations. The result has an important implication; no combination of routing protocol and MAC protocol is the best over all situations. Also, the performance analysis of protocols at a given level in the protocol stack needs to be studied not locally in isolation but as a part of the complete protocol stack. A novel aspect of our work is the use of statistical technique, ANOVA (Analysis of Variance) to characterize the effect of routing protocols on MAC protocols. This technique is of independent interest and can be utilized in several other simulation and empirical studies.

  6. Controllable Curved Mirrors Made from Single-Layer EAP Films

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart

    2004-01-01

    A document proposes that lightweight, deployable, large-aperture, controllable curved mirrors made of reflectively coated thin electroactive-polymer (EAP) films be developed for use in spaceborne microwave and optical systems. In these mirrors, the EAP films would serve as both structures and actuators. EAPs that are potentially suitable for such use include piezoelectric, electrostrictive, ferroelectric, and dielectric polymers. These materials exhibit strains proportional to the squares of applied electric fields. Utilizing this phenomenon, a curved mirror according to the proposal could be made from a flat film, upon which a nonuniform electrostatic potential (decreasing from the center toward the edge) would be imposed to obtain a required curvature. The effect would be analogous to that of an old-fashioned metalworking practice in which a flat metal sheet is made into a bowl by hammering it repeatedly, the frequency of hammer blows decreasing with distance from the center. In operation, the nonuniform electrostatic potential could be imposed by use of an electron gun. Calculations have shown that by use of a single- layer film made of a currently available EAP, it would be possible to control the focal length of a 2-m-diameter mirror from infinity to 1.25 m.

  7. Fertility Effects of Abortion and Birth Control Pill Access for Minors

    PubMed Central

    GULDI, MELANIE

    2008-01-01

    This article empirically assesses whether age-restricted access to abortion and the birth control pill influence minors’ fertility in the United States. There is not a strong consensus in previous literature regarding the relationship between laws restricting minors’ access to abortion and minors’ birthrates. This is the first study to recognize that state laws in place prior to the 1973 Roe v. Wade decision enabled minors to legally consent to surgical treatment—including abortion—in some states but not in others, and to construct abortion access variables reflecting this. In this article, age-specific policy variables measure either a minor’s legal ability to obtain an abortion or to obtain the birth control pill without parental involvement. I find fairly strong evidence that young women’s birthrates dropped as a result of abortion access as well as evidence that birth control pill access led to a drop in birthrates among whites. PMID:19110899

  8. Optimum forebody shaping for axisymmetric submersibles with turbulent boundary layers and BLO (Boundary Layer Control) afterbodies

    NASA Astrophysics Data System (ADS)

    Neumann, B. J.

    1983-07-01

    One objective of the Advanced Undersea Vehicle (AUV) program is to design a low drag vehicle. The approach in this investigation is boundary layer control by means of an annular suction slot located on the afterbody. Although wind tunnel data showed significant reduction in propulsive power over conventional shapes, an attempt was made to achieve further reduction by means of forebody shaping. Two methods were used to vary the geometric parameters for this analysis. The direct method, based on the mathematical development of the Series 58 bodies, allows the definition of a shape by a fifth-order polynomial based on the four fundamental parameters of fineness ratio, nose radius of curvature, location of maximum thickness, and prismatic coefficient. The inverse method allows various velocity distributions to define the body shape. The shapes derived by this method have flat velocity distributions and show similar trends to the polynomial shapes (about 3-percent reduction in propulsive power). The range of fineness ratios analyzed was from 1 to 10 at a volume-based Reynolds number of 3.2 million. In the range of 2.5 to 8, fineness ratio did not affect propulsive power more than 6 percent. A maximum improvement of 3 percent as shown by varying the meridian section.

  9. 75 FR 71790 - Second Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-24

    ... Federal Aviation Administration Second Meeting: RTCA Special Committee 224: Airport Security Access... Committee 224 meeting: Airport Security Access Control Systems (Update to DO-230B). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport...

  10. 76 FR 38742 - Seventh Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ... Federal Aviation Administration Seventh Meeting: RTCA Special Committee 224: Airport Security Access... Committee 224 meeting: Airport Security Access Control Systems (Update to DO-230B). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport...

  11. 76 FR 3931 - Fourth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-21

    ... Federal Aviation Administration Fourth Meeting: RTCA Special Committee 224: Airport Security Access... Committee 224 Meeting: Airport Security Access Control Systems (Update to DO-230B). SUMMARY: The FAA is issuing this notice to advise the public of a meeting of RTCA Special Committee 224: Airport...

  12. Control System For Cryogenic THD Layering At The National Ignition Facility

    SciTech Connect

    Fedorov, M; Blubaugh, J; Edwards, O; Mauvais, M; Sanchez, R; Wilson, B

    2011-03-18

    The National Ignition Facility (NIF) is the world largest and most energetic laser system for Inertial Confinement Fusion (ICF). In 2010, NIF began ignition experiments using cryogenically cooled targets containing layers of the tritium-hydrogen-deuterium (THD) fuel. The 75 {micro}m thick layer is formed inside of the 2 mm target capsule at temperatures of approximately 18 K. The ICF target designs require sub-micron smoothness of the THD ice layers. Formation of such layers is still an active research area, requiring a flexible control system capable of executing the evolving layering protocols. This task is performed by the Cryogenic Target Subsystem (CTS) of the NIF Integrated Computer Control System (ICCS). The CTS provides cryogenic temperature control with the 1 mK resolution required for beta-layering and for the thermal gradient fill of the capsule. The CTS also includes a 3-axis x-ray radiography engine for phase contrast imaging of the ice layers inside of the plastic and beryllium capsules. In addition to automatic control engines, CTS is integrated with the Matlab interactive programming environment to allow flexibility in experimental layering protocols. The CTS Layering Matlab Toolbox provides the tools for layer image analysis, system characterization and cryogenic control. The CTS Layering Report tool generates qualification metrics of the layers, such as concentricity of the layer and roughness of the growth boundary grooves. The CTS activities are automatically coordinated with other NIF controls in the carefully orchestrated NIF Shot Sequence.

  13. The Smart Card concept applied to access control

    SciTech Connect

    Seidman, S.

    1986-01-01

    Passwords tend to be handled carelessly, and so are easily lost or stolen. Because they are intangible, their loss or theft generally goes unnoticed. Because they are constant, they may be used by anyone for as long as they remain in active use by a legitimate user. A step up in password security is offered by a new range of products which generate a new code each time the device is used. Devices are being produced in packages as small as a standard plastic credit card, including internal battery power, integral keyboard and LCD display. Security features of the Smart Card are reviewed, and several random access code generators currently available in the commercial marketplace are described.

  14. Energy-efficient boarder node medium access control protocol for wireless sensor networks.

    PubMed

    Razaque, Abdul; Elleithy, Khaled M

    2014-03-12

    This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC) for wireless sensor networks (WSNs), which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN), which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS), which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM) model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS), which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  15. Energy-Efficient Boarder Node Medium Access Control Protocol for Wireless Sensor Networks

    PubMed Central

    Razaque, Abdul; Elleithy, Khaled M.

    2014-01-01

    This paper introduces the design, implementation, and performance analysis of the scalable and mobility-aware hybrid protocol named boarder node medium access control (BN-MAC) for wireless sensor networks (WSNs), which leverages the characteristics of scheduled and contention-based MAC protocols. Like contention-based MAC protocols, BN-MAC achieves high channel utilization, network adaptability under heavy traffic and mobility, and low latency and overhead. Like schedule-based MAC protocols, BN-MAC reduces idle listening time, emissions, and collision handling at low cost at one-hop neighbor nodes and achieves high channel utilization under heavy network loads. BN-MAC is particularly designed for region-wise WSNs. Each region is controlled by a boarder node (BN), which is of paramount importance. The BN coordinates with the remaining nodes within and beyond the region. Unlike other hybrid MAC protocols, BN-MAC incorporates three promising models that further reduce the energy consumption, idle listening time, overhearing, and congestion to improve the throughput and reduce the latency. One of the models used with BN-MAC is automatic active and sleep (AAS), which reduces the ideal listening time. When nodes finish their monitoring process, AAS lets them automatically go into the sleep state to avoid the idle listening state. Another model used in BN-MAC is the intelligent decision-making (IDM) model, which helps the nodes sense the nature of the environment. Based on the nature of the environment, the nodes decide whether to use the active or passive mode. This decision power of the nodes further reduces energy consumption because the nodes turn off the radio of the transceiver in the passive mode. The third model is the least-distance smart neighboring search (LDSNS), which determines the shortest efficient path to the one-hop neighbor and also provides cross-layering support to handle the mobility of the nodes. The BN-MAC also incorporates a semi

  16. Biodegradable, multi-layered coatings for controlled release of small molecules†

    PubMed Central

    Amir, Elizabeth; Antoni, Per; Campos, Luis M.; Damiron, Denis; Gupta, Nalini; Amir, Roey J.; Pesika, Noshir; Drockenmuller, Eric

    2014-01-01

    Incorporation of orthogonal functional groups into biodegradable polymers permits the fabrication of multi-layered thin films with improved adhesion and tunable degradation profiles. The bi-layer structure also allows for accurate control over small molecule release. PMID:22499161

  17. Morphology Control of Zinc Oxide Nanostructure on Single Layer Graphene.

    PubMed

    Ahn, Seungbae; Vijayarangamuthu, K; Jeon, Ki-Jeon

    2016-05-01

    Various morphologies of zinc oxide (ZnO) nanostructures on single layer graphene were synthesized by electrodeposition method. The current density was utilized to control the morphology of the ZnO. The Scanning Electron Microscope (SEM) was used to examine the surface morphology of the samples. SEM analysis shows morphology changes to nanorod, flower, and flakes with increase in the current density from 0.1, 0.2, and 0.3 mA/cm(-1) respectively. The XRD, XPS, and Raman spectroscopy were adopted to characterize the ZnO nanostructure and to understand the formation of various morphologies. The Raman result clearly shows extra modes due to for flakes structure caused by c-axis orientation along the substrate direction. Further, XPS data also supports formation of ZnO without any other intermediate compound such as Zn(OH)2. The formation of various morphologies was correlated to the formation different ratio of Zn2+ and OH- ions and the change in growth direction due to various current densities. PMID:27483766

  18. A contextual role-based access control authorization model for electronic patient record.

    PubMed

    Motta, Gustavo H M B; Furuie, Sergio S

    2003-09-01

    The design of proper models for authorization and access control for electronic patient record (EPR) is essential to a wide scale use of EPR in large health organizations. In this paper, we propose a contextual role-based access control authorization model aiming to increase the patient privacy and the confidentiality of patient data, whereas being flexible enough to consider specific cases. This model regulates user's access to EPR based on organizational roles. It supports a role-tree hierarchy with authorization inheritance; positive and negative authorizations; static and dynamic separation of duties based on weak and strong role conflicts. Contextual authorizations use environmental information available at access time, like user/patient relationship, in order to decide whether a user is allowed to access an EPR resource. This enables the specification of a more flexible and precise authorization policy, where permission is granted or denied according to the right and the need of the user to carry out a particular job function.

  19. An access control model with high security for distributed workflow and real-time application

    NASA Astrophysics Data System (ADS)

    Han, Ruo-Fei; Wang, Hou-Xiang

    2007-11-01

    The traditional mandatory access control policy (MAC) is regarded as a policy with strict regulation and poor flexibility. The security policy of MAC is so compelling that few information systems would adopt it at the cost of facility, except some particular cases with high security requirement as military or government application. However, with the increasing requirement for flexibility, even some access control systems in military application have switched to role-based access control (RBAC) which is well known as flexible. Though RBAC can meet the demands for flexibility but it is weak in dynamic authorization and consequently can not fit well in the workflow management systems. The task-role-based access control (T-RBAC) is then introduced to solve the problem. It combines both the advantages of RBAC and task-based access control (TBAC) which uses task to manage permissions dynamically. To satisfy the requirement of system which is distributed, well defined with workflow process and critically for time accuracy, this paper will analyze the spirit of MAC, introduce it into the improved T&RBAC model which is based on T-RBAC. At last, a conceptual task-role-based access control model with high security for distributed workflow and real-time application (A_T&RBAC) is built, and its performance is simply analyzed.

  20. 75 FR 69791 - Risk Management Controls for Brokers or Dealers With Market Access

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... Exchange Commission 17 CFR Part 240 Risk Management Controls for Brokers or Dealers With Market Access... Regulations#0;#0; ] SECURITIES AND EXCHANGE COMMISSION 17 CFR Part 240 RIN 3235-AK53 Risk Management Controls.... The required financial risk management controls and supervisory procedures must be reasonably...

  1. 76 FR 38293 - Risk Management Controls for Brokers or Dealers With Market Access

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-30

    ... COMMISSION 17 CFR Part 240 RIN 3235-AK53 Risk Management Controls for Brokers or Dealers With Market Access... establish, document, and maintain a system of risk management controls and supervisory procedures that... develop, test, and implement the relevant risk management controls and supervisory procedures...

  2. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation

    PubMed Central

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type–III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  3. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation.

    PubMed

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type-III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  4. Thalamic control of layer 1 circuits in prefrontal cortex

    PubMed Central

    Cruikshank, Scott J.; Ahmed, Omar J.; Stevens, Tanya R.; Patrick, Saundra L.; Gonzalez, Amalia N.; Elmaleh, Margot; Connors, Barry W.

    2012-01-01

    Knowledge of thalamocortical (TC) processing comes mainly from studying core thalamic systems that project to middle layers of primary sensory cortices. However, most thalamic relay neurons comprise a matrix of cells that are densest in the “nonspecific” thalamic nuclei and usually target layer 1 of multiple cortical areas. A longstanding hypothesis is that matrix TC systems are crucial for regulating neocortical excitability during changing behavioral states, yet we know almost nothing about the mechanisms of such regulation. It is also unclear whether synaptic and circuit mechanisms that are well established for core sensory TC systems apply to matrix TC systems. Here we describe studies of thalamic matrix influences on mouse prefrontal cortex using optogenetic and in vitro electrophysiology techniques. Channelrhodopsin-2 was expressed in midline and paralaminar (matrix) thalamic neurons, and their layer 1-projecting TC axons were activated optically. Contrary to conventional views, we found that matrix TC projections to layer 1 could transmit relatively strong, fast, high-fidelity synaptic signals. Layer 1 TC projections preferentially drove inhibitory interneurons of layer 1, especially those of the late-spiking subtype, and often triggered feedforward inhibition in both layer 1 interneurons and pyramidal cells of layers 2/3. Responses during repetitive stimulation were far more sustained for matrix than for core sensory TC pathways. Thus, matrix TC circuits appear to be specialized for robust transmission over relatively extended periods, consistent with the sort of persistent activation observed during working memory and potentially applicable to state-dependent regulation of excitability. PMID:23223300

  5. Cognitive Control and Lexical Access in Younger and Older Bilinguals

    ERIC Educational Resources Information Center

    Bialystok, Ellen; Craik, Fergus; Luk, Gigi

    2008-01-01

    Ninety-six participants, who were younger (20 years) or older (68 years) adults and either monolingual or bilingual, completed tasks assessing working memory, lexical retrieval, and executive control. Younger participants performed most of the tasks better than older participants, confirming the effect of aging on these processes. The effect of…

  6. Direct intervention of hairpin structures for turbulent boundary-layer control

    NASA Astrophysics Data System (ADS)

    Kang, Yong-Duck; Choi, Kwing-So; Chun, Ho Hwan

    2008-10-01

    Direct intervention of large-scale, outer-layer structures of a turbulent boundary layer has been carried out by counteracting the upwash motion of hairpin vortices with jets issued from a nozzle placed outside the boundary layer. The methodology of this turbulent boundary-layer control is similar in concept to the opposition control of near-wall turbulence, where the induced velocity field of vortical motion during the turbulence activities is opposed by suction and blowing at the wall. Unlike wall-based turbulence control techniques whose time and length scales reduce with an increase in the Reynolds number, scales of the proposed control are those of the outer layer, making this control technique highly practical. Here we show some results from a direct intervention of hairpin structures in a turbulent boundary layer, demonstrating that this is a promising technique for turbulence control.

  7. Trust-Based Access Control Model from Sociological Approach in Dynamic Online Social Network Environment

    PubMed Central

    Kim, Seungjoo

    2014-01-01

    There has been an explosive increase in the population of the OSN (online social network) in recent years. The OSN provides users with many opportunities to communicate among friends and family. Further, it facilitates developing new relationships with previously unknown people having similar beliefs or interests. However, the OSN can expose users to adverse effects such as privacy breaches, the disclosing of uncontrolled material, and the disseminating of false information. Traditional access control models such as MAC, DAC, and RBAC are applied to the OSN to address these problems. However, these models are not suitable for the dynamic OSN environment because user behavior in the OSN is unpredictable and static access control imposes a burden on the users to change the access control rules individually. We propose a dynamic trust-based access control for the OSN to address the problems of the traditional static access control. Moreover, we provide novel criteria to evaluate trust factors such as sociological approach and evaluate a method to calculate the dynamic trust values. The proposed method can monitor negative behavior and modify access permission levels dynamically to prevent the indiscriminate disclosure of information. PMID:25374943

  8. Trust-based access control model from sociological approach in dynamic online social network environment.

    PubMed

    Baek, Seungsoo; Kim, Seungjoo

    2014-01-01

    There has been an explosive increase in the population of the OSN (online social network) in recent years. The OSN provides users with many opportunities to communicate among friends and family. Further, it facilitates developing new relationships with previously unknown people having similar beliefs or interests. However, the OSN can expose users to adverse effects such as privacy breaches, the disclosing of uncontrolled material, and the disseminating of false information. Traditional access control models such as MAC, DAC, and RBAC are applied to the OSN to address these problems. However, these models are not suitable for the dynamic OSN environment because user behavior in the OSN is unpredictable and static access control imposes a burden on the users to change the access control rules individually. We propose a dynamic trust-based access control for the OSN to address the problems of the traditional static access control. Moreover, we provide novel criteria to evaluate trust factors such as sociological approach and evaluate a method to calculate the dynamic trust values. The proposed method can monitor negative behavior and modify access permission levels dynamically to prevent the indiscriminate disclosure of information.

  9. Generalized access control strategies for integrated services token passing systems

    NASA Astrophysics Data System (ADS)

    Pang, Joseph W. M.; Tobagi, Fouad A.; Boyd, Stephen

    1994-08-01

    The demand for integrated services local area networks is increasing at a rapid pace with the advent of many new and exciting applications: office and factory automation, distributed computing, and multimedia communications. To support these new applications, it is imperative to integrate traffic with diverse statistical characteristics and differing delay requirements on the same network. An attractive approach for integrating traffic has been adopted in two token passing local area network standards, the IEEE 802.4 token bus standard and FDDI. The idea is to control the transmissions of each station based on a distributed timing algorithm, so as to achieve the following goals: (1) to limit the token cycles so that time-critical traffic can be accommodated, and (2) to allocate pre-specified bandwidths to different stations when the network is overloaded. We have investigated the analysis and design of this protocol. In this paper, we generalize the transmission control algorithm used previously. The major advantages of the generalization over the original protocol are: (1) it provides a much expanded design space, (2) it guarantees convergent behavior, and (3) it gives meaningful insights into the dynamics of the basic control algorithm.

  10. An action-based fine-grained access control mechanism for structured documents and its application.

    PubMed

    Su, Mang; Li, Fenghua; Tang, Zhi; Yu, Yinyan; Zhou, Bo

    2014-01-01

    This paper presents an action-based fine-grained access control mechanism for structured documents. Firstly, we define a describing model for structured documents and analyze the application scenarios. The describing model could support the permission management on chapters, pages, sections, words, and pictures of structured documents. Secondly, based on the action-based access control (ABAC) model, we propose a fine-grained control protocol for structured documents by introducing temporal state and environmental state. The protocol covering different stages from document creation, to permission specification and usage control are given by using the Z-notation. Finally, we give the implementation of our mechanism and make the comparisons between the existing methods and our mechanism. The result shows that our mechanism could provide the better solution of fine-grained access control for structured documents in complicated networks. Moreover, it is more flexible and practical.

  11. An Action-Based Fine-Grained Access Control Mechanism for Structured Documents and Its Application

    PubMed Central

    Su, Mang; Li, Fenghua; Tang, Zhi; Yu, Yinyan; Zhou, Bo

    2014-01-01

    This paper presents an action-based fine-grained access control mechanism for structured documents. Firstly, we define a describing model for structured documents and analyze the application scenarios. The describing model could support the permission management on chapters, pages, sections, words, and pictures of structured documents. Secondly, based on the action-based access control (ABAC) model, we propose a fine-grained control protocol for structured documents by introducing temporal state and environmental state. The protocol covering different stages from document creation, to permission specification and usage control are given by using the Z-notation. Finally, we give the implementation of our mechanism and make the comparisons between the existing methods and our mechanism. The result shows that our mechanism could provide the better solution of fine-grained access control for structured documents in complicated networks. Moreover, it is more flexible and practical. PMID:25136651

  12. CMP Control of Multi-Layer Inter-Layer Dielectrics (ILD) using X-ray Reflectivity

    SciTech Connect

    Bryant, Ross E.; Porter, Hethel; Gallegos, Jesus; O'Dell, Jeremy; Agnihotri, Dileep

    2007-09-26

    Thin sacrificial films are used as cap layer in the back-end semiconductor processing for protecting the bulk porous inter-layer low-k dielectric during the CMP process. The existing optical measurement techniques struggle to separate these thin films from the bulk low-k due to very similar optical coefficients. Glancing angle x-ray reflectivity is well suited for separation of thin sacrificial film and bulk dielectric film as x-ray reflectivity depends strongly on changes in electron densities for two materials. This paper discusses the x-ray reflectivity technique and its applications for measurement of low-k stack and sacrificial oxide post CMP.

  13. Advanced Guidance and Control for Hypersonics and Space Access

    NASA Technical Reports Server (NTRS)

    Hanson, John M.; Hall, Charles E.; Mulqueen, John A.; Jones, Robert E.

    2003-01-01

    Advanced guidance and control (AG&C) technologies are critical for meeting safety, reliability, and cost requirements for the next generation of reusable launch vehicle (RLV), whether it is fully rocket-powered or has air- breathing components. This becomes clear upon examining the number of expendable launch vehicle failures in the recent past where AG&C technologies could have saved a RLV with the same failure mode, the additional vehicle problems where t h i s technology applies, and the costs and time associated with mission design with or without all these failure issues. The state-of-the-art in guidance and control technology, as well as in computing technology, is the point where we can look to the possibility of being able to safely return a RLV in any situation where it can physically be recovered. This paper outlines reasons for AWC, current technology efforts, and the additional work needed for making this goal a reality. There are a number of approaches to AG&C that have the potential for achieving the desired goals. For some of these methods, we compare the results of tests designed to demonstrate the achievement of the goals. Tests up to now have been focused on rocket-powered vehicles; application to hypersonic air-breathers is planned. We list the test cases used to demonstrate that the desired results are achieved, briefly describe an automated test scoring method, and display results of the tests. Some of the technology components have reached the maturity level where they are ready for application to a new vehicle concept, while others are not far along in development.

  14. Steganography-based access control to medical data hidden in electrocardiogram.

    PubMed

    Mai, Vu; Khalil, Ibrahim; Ibaida, Ayman

    2013-01-01

    Steganographic techniques allow secret data to be embedded inside another host data such as an image or a text file without significant changes to the quality of the host data. In this research, we demonstrate how steganography can be used as the main mechanism to build an access control model that gives data owners complete control to their sensitive cardiac health information hidden in their own Electrocardiograms. Our access control model is able to protect the privacy of users, the confidentiality of medical data, reduce storage space and make it more efficient to upload and download large amount of data.

  15. Steganography-based access control to medical data hidden in electrocardiogram.

    PubMed

    Mai, Vu; Khalil, Ibrahim; Ibaida, Ayman

    2013-01-01

    Steganographic techniques allow secret data to be embedded inside another host data such as an image or a text file without significant changes to the quality of the host data. In this research, we demonstrate how steganography can be used as the main mechanism to build an access control model that gives data owners complete control to their sensitive cardiac health information hidden in their own Electrocardiograms. Our access control model is able to protect the privacy of users, the confidentiality of medical data, reduce storage space and make it more efficient to upload and download large amount of data. PMID:24109934

  16. Thermoresponsive nanofabricated substratum for the engineering of three-dimensional tissues with layer-by-layer architectural control.

    PubMed

    Jiao, Alex; Trosper, Nicole E; Yang, Hee Seok; Kim, Jinsung; Tsui, Jonathan H; Frankel, Samuel D; Murry, Charles E; Kim, Deok-Ho

    2014-05-27

    Current tissue engineering methods lack the ability to properly recreate scaffold-free, cell-dense tissues with physiological structures. Recent studies have shown that the use of nanoscale cues allows for precise control over large-area 2D tissue structures without restricting cell growth or cell density. In this study, we developed a simple and versatile platform combining a thermoresponsive nanofabricated substratum (TNFS) incorporating nanotopographical cues and the gel casting method for the fabrication of scaffold-free 3D tissues. Our TNFS allows for the structural control of aligned cell monolayers which can be spontaneously detached via a change in culture temperature. Utilizing our gel casting method, viable, aligned cell sheets can be transferred without loss of anisotropy or stacked with control over individual layer orientations. Transferred cell sheets and individual cell layers within multilayered tissues robustly retain structural anisotropy, allowing for the fabrication of scaffold-free, 3D tissues with hierarchical control of overall tissue structure.

  17. Analysis of Decision Factors for the Application of Information Access Controls within the Organization

    ERIC Educational Resources Information Center

    Foerster, Carl A.

    2013-01-01

    The application of access controls on internal information necessarily impacts the availability of that information for sharing inside the enterprise. The decisions establishing the degree of control are a crucial first step to balance the requirements to protect and share. This research develops a set of basic decision factors and examines other…

  18. 50 CFR 622.17 - South Atlantic golden crab controlled access.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false South Atlantic golden crab controlled... ATLANTIC Effort Limitations § 622.17 South Atlantic golden crab controlled access. (a) General. In accordance with the procedures specified in the Fishery Management Plan for the Golden Crab Fishery of...

  19. 50 CFR 622.17 - South Atlantic golden crab controlled access.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false South Atlantic golden crab controlled... ATLANTIC Effort Limitations § 622.17 South Atlantic golden crab controlled access. (a) General. In accordance with the procedures specified in the Fishery Management Plan for the Golden Crab Fishery of...

  20. 50 CFR 622.241 - South Atlantic golden crab controlled access.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false South Atlantic golden crab controlled..., AND SOUTH ATLANTIC Golden Crab Fishery of the South Atlantic Region § 622.241 South Atlantic golden crab controlled access. (a) General. In accordance with the procedures specified in the...

  1. 50 CFR 622.241 - South Atlantic golden crab controlled access.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false South Atlantic golden crab controlled..., AND SOUTH ATLANTIC Golden Crab Fishery of the South Atlantic Region § 622.241 South Atlantic golden crab controlled access. (a) General. In accordance with the procedures specified in the...

  2. 50 CFR 622.17 - South Atlantic golden crab controlled access.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false South Atlantic golden crab controlled... ATLANTIC Effort Limitations § 622.17 South Atlantic golden crab controlled access. (a) General. In accordance with the procedures specified in the Fishery Management Plan for the Golden Crab Fishery of...

  3. Temperature and Humidity Control in Multi-Layered Garments

    NASA Astrophysics Data System (ADS)

    Lee, Duck Weon

    2011-12-01

    The purpose of this research is to measure a property of a multilayered fabric system by using heat energy and vapor flow in terms of thermodynamics. By observing change in the heat energy and vapor flow passing through the multilayered fabric system, this research is able to provide precise information about a property of individual fabric layer composing the multilayered fabric system. This new research idea originates from a concept that, when heat energy and vapor flow pass through the layer or membrane, the amount of the heat energy and vapor flow is changed in accordance with a function of the layer or membrane. In particular, the amount of the vapor flow is apparently changed according to the fabric or membranes' structure and material property in a given environmental condition. The research conducts an experiment by using 'the energy source,' which is newly and innovatively developed, measuring temperature and relative humidity in the multilayered system. Through experimental data, the research calculates the amount of heat energy flow in the microclimates and fabric by using Stefan Boltzmann equation, Newton's law of cooling, Fourier's law, and Clausius- Clapeyron Relation. The research explains what properties of the fabric layers influence the energy flow attributable to conduction in the multilayered system consisting individual layers. In addition, the research shows that it is possible to build an optimized multilayered system under a variety of environmental conditions.

  4. Controlled templating of porphyrins by a molecular command layer.

    PubMed

    den Boer, Duncan; Habets, Thomas; Coenen, Michiel J J; van der Maas, Minko; Peters, Theo P J; Crossley, Maxwell J; Khoury, Tony; Rowan, Alan E; Nolte, Roeland J M; Speller, Sylvia; Elemans, Johannes A A W

    2011-03-15

    The copper porphyrin (5,10,15,20-tetraundecylporphyrinato)copper(II) can be templated in a well-defined arrangement using p-(hexadecyloxycarbonyl)phenylacetylene as a command layer on graphite. The bicomponent system was characterized at the submolecular level at a solid/liquid interface by scanning tunneling microscopy (STM). It is proposed that the layer of copper porphyrins is templated on top of the command layer in a hierarchical fashion, via a combination of intermolecular π-π stacking and van der Waals interactions. A very subtle effect, i.e., a superstructure in the alkyl chain region of the phenylacetylene monolayers, was identified as a decisive factor for the templating process.

  5. 48 CFR 1552.235-75 - Access to Toxic Substances Control Act Confidential Business Information (APR 1996).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 6 2014-10-01 2014-10-01 false Access to Toxic Substances... CONTRACT CLAUSES Texts of Provisions and Clauses 1552.235-75 Access to Toxic Substances Control Act...: Access to Toxic Substances Control Act Confidential Business Information (APR 1996) In order to...

  6. 48 CFR 1552.235-75 - Access to Toxic Substances Control Act Confidential Business Information (APR 1996).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Access to Toxic Substances... CONTRACT CLAUSES Texts of Provisions and Clauses 1552.235-75 Access to Toxic Substances Control Act...: Access to Toxic Substances Control Act Confidential Business Information (APR 1996) In order to...

  7. 48 CFR 1552.235-75 - Access to Toxic Substances Control Act Confidential Business Information (APR 1996).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 6 2012-10-01 2012-10-01 false Access to Toxic Substances... CONTRACT CLAUSES Texts of Provisions and Clauses 1552.235-75 Access to Toxic Substances Control Act...: Access to Toxic Substances Control Act Confidential Business Information (APR 1996) In order to...

  8. MAAC: a software tool for user authentication and access control to the electronic patient record in an open distributed environment

    NASA Astrophysics Data System (ADS)

    Motta, Gustavo H.; Furuie, Sergio S.

    2004-04-01

    Designing proper models for authorization and access control for the electronic patient record (EPR) is essential to wide scale use of the EPR in large health organizations. This work presents MAAC (Middleware for Authentication and Access Control), a tool that implements a contextual role-based access control (RBAC) authorization model. RBAC regulates user"s access to computers resources based on their organizational roles. A contextual authorization uses environmental information available at access-request time, like user/patient relationship, in order to decide whether a user has the right to access an EPR resource. The software architecture where MAAC is implemented uses Lightweight Directory Access Protocol, Java programming language and the CORBA/OMG standards CORBA Security Service and Resource Access Decision Facility. With those open and distributed standards, heterogeneous EPR components can request user authentication and access authorization services in a unified and consistent fashion across multiple platforms.

  9. Effects of automatic/controlled access processes on semantic memory in Alzheimer's disease.

    PubMed

    Arroyo-Anlló, Eva M; Bellouard, Stéphanie; Ingrand, Pierre; Gil, Roger

    2011-01-01

    This study examines the impact of automatic/controlled access processes on the semantic network in 30 patients with Alzheimer's disease (AD). The AD group was compared with a control group using a battery of neuropsychological tests, a variation of Hodges's semantic testing battery, designed to assess semantic knowledge. The AD group had markedly lower scores than the normal group on each semantic test, but with a different degree of deterioration depending on the nature of the processes (controlled/automatic) in accessing the semantic network. AD patients had poorer performances on the explicit semantic tasks mainly involving controlled-process access (e.g., the WAIS Similarities Subtest) than those involving mainly automatic-process access (e.g., the Verbal Automatism test). Analyses of confidence intervals allowed a gradient of impaired performances in increasing order to be elaborated: a) the Verbal Automatism test, b) the WAIS Vocabulary Subtest, c) the WAIS Information Subtest, d) the Letter Fluency Task, e) Naming as a Response to Definition, f) the Category Fluency Task, g) the WAIS Similarities Subtest, and h) the Oral Denomination 80 Test. The results of our study suggest that explicit semantic tasks needing passive or automatic processes to access semantic memory would be better preserved in AD. PMID:21471640

  10. Sustained, Controlled and Stimuli-Responsive Drug Release Systems Based on Nanoporous Anodic Alumina with Layer-by-Layer Polyelectrolyte.

    PubMed

    Porta-I-Batalla, Maria; Eckstein, Chris; Xifré-Pérez, Elisabet; Formentín, Pilar; Ferré-Borrull, J; Marsal, Lluis F

    2016-12-01

    Controlled drug delivery systems are an encouraging solution to some drug disadvantages such as reduced solubility, deprived biodistribution, tissue damage, fast breakdown of the drug, cytotoxicity, or side effects. Self-ordered nanoporous anodic alumina is an auspicious material for drug delivery due to its biocompatibility, stability, and controllable pore geometry. Its use in drug delivery applications has been explored in several fields, including therapeutic devices for bone and dental tissue engineering, coronary stent implants, and carriers for transplanted cells. In this work, we have created and analyzed a stimuli-responsive drug delivery system based on layer-by-layer pH-responsive polyelectrolyte and nanoporous anodic alumina. The results demonstrate that it is possible to control the drug release using a polyelectrolyte multilayer coating that will act as a gate. PMID:27550052

  11. Sustained, Controlled and Stimuli-Responsive Drug Release Systems Based on Nanoporous Anodic Alumina with Layer-by-Layer Polyelectrolyte

    NASA Astrophysics Data System (ADS)

    Porta-i-Batalla, Maria; Eckstein, Chris; Xifré-Pérez, Elisabet; Formentín, Pilar; Ferré-Borrull, J.; Marsal, Lluis F.

    2016-08-01

    Controlled drug delivery systems are an encouraging solution to some drug disadvantages such as reduced solubility, deprived biodistribution, tissue damage, fast breakdown of the drug, cytotoxicity, or side effects. Self-ordered nanoporous anodic alumina is an auspicious material for drug delivery due to its biocompatibility, stability, and controllable pore geometry. Its use in drug delivery applications has been explored in several fields, including therapeutic devices for bone and dental tissue engineering, coronary stent implants, and carriers for transplanted cells. In this work, we have created and analyzed a stimuli-responsive drug delivery system based on layer-by-layer pH-responsive polyelectrolyte and nanoporous anodic alumina. The results demonstrate that it is possible to control the drug release using a polyelectrolyte multilayer coating that will act as a gate.

  12. Mechanism of power consumption inhibitive multi-layer Zn:SiO2/SiO2 structure resistance random access memory

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Tsai, Tsung-Ming; Chang, Ting-Chang; Chang, Kuan-Chang; Chen, Kai-Huang; Lou, Jen-Chung; Young, Tai-Fa; Chen, Jung-Hui; Huang, Syuan-Yong; Chen, Min-Chen; Shih, Chih-Cheng; Chen, Hsin-Lu; Pan, Jhih-Hong; Tung, Cheng-Wei; Syu, Yong-En; Sze, Simon M.

    2013-12-01

    In this paper, multi-layer Zn:SiO2/SiO2 structure is introduced to reduce the operation power consumption of resistive random access memory (RRAM) device by modifying the filament formation process. And the configuration of multi-layer Zn:SiO2/SiO2 structure is confirmed and demonstrated by auger electron spectrum. Material analysis together with conduction current fitting is applied to qualitatively evaluate the carrier conduction mechanism on both low resistance state and high resistance state. Finally, single layer and multilayer conduction models are proposed, respectively, to clarify the corresponding conduction characteristics of two types of RRAM devices.

  13. Dissecting the genetic control of natural variation in salt tolerance of Arabidopsis thaliana accessions

    PubMed Central

    Katori, Taku; Ikeda, Akiro; Iuchi, Satoshi; Kobayashi, Masatomo; Shinozaki, Kazuo; Maehashi, Kenji; Sakata, Yoichi; Tanaka, Shigeo; Taji, Teruaki

    2010-01-01

    Many accessions (ecotypes) of Arabidopsis have been collected. Although few differences exist among their nucleotide sequences, these subtle differences induce large genetic variation in phenotypic traits such as stress tolerance and flowering time. To understand the natural variability in salt tolerance, large-scale soil pot experiments were performed to evaluate salt tolerance among 350 Arabidopsis thaliana accessions. The evaluation revealed a wide variation in the salt tolerance among accessions. Several accessions, including Bu-5, Bur-0, Ll-1, Wl-0, and Zu-0, exhibited marked stress tolerance compared with a salt-sensitive experimental accession, Col-0. The salt-tolerant accessions were also evaluated by agar plate assays. The data obtained by the large-scale assay correlated well with the results of a salt acclimation (SA) assay, in which plants were transferred to high-salinity medium following placement on moderate-salinity medium for 7 d. Genetic analyses indicated that the salt tolerance without SA is a quantitative trait under polygenic control, whereas salt tolerance with SA is regulated by a single gene located on chromosome 5 that is common among the markedly salt-tolerant accessions. These results provide important information for understanding the mechanisms underlying natural variation of salt tolerance in Arabidopsis. PMID:20080827

  14. Resistance switching behavior of ZnO resistive random access memory with a reduced graphene oxide capping layer

    NASA Astrophysics Data System (ADS)

    Lin, Cheng-Li; Chang, Wei-Yi; Huang, Yen-Lun; Juan, Pi-Chun; Wang, Tse-Wen; Hung, Ke-Yu; Hsieh, Cheng-Yu; Kang, Tsung-Kuei; Shi, Jen-Bin

    2015-04-01

    In this work, we investigate the characteristics of ZnO resistive random access memory (RRAM) with a reduced graphene oxide (rGO) capping layer and the polarity effect of the SET/RESET bias on the RRAM. The rGO film insertion enhances the stability of the current-voltage (I-V) switching curve and the superior resistance ratio (˜105) of high-resistance state (HRS) to low-resistance state (LRS). Using the appropriate polarity of the SET/RESET bias applied to the rGO-capped ZnO RRAM enables the oxygen ions to move mainly at the interface of the rGO and ZnO films, resulting in the best performance. Presumably, the rGO film acts as an oxygen reservoir and enhances the easy in and out motion of the oxygen ions from the rGO film. The rGO film also prevents the interaction of oxygen ions and the Al electrode, resulting in excellent performance. In a pulse endurance test, the rGO-capped ZnO RRAM reveals superior endurance of up to 108 cycles over that of the ZnO RRAM without rGO insertion (106 cycles).

  15. Assembly-Controlled Permeability of Layer-by-Layer Polymeric Microcapsules Using a Tapered Fluidized Bed.

    PubMed

    Noi, Ka Fung; Roozmand, Ali; Björnmalm, Mattias; Richardson, Joseph J; Franks, George V; Caruso, Frank

    2015-12-23

    Nano- and microcapsules engineered through layer-by-layer (LbL) assembly are finding an increasingly large number of applications as catalysts, electrochemical biosensors, bioreactors, artificial cells and drug delivery vehicles. While centrifugation-based LbL assembly is the most common method for coating template particles and preparing capsules, it is a batch process and requires frequent intervention that renders the system challenging to automate and scale up. Here, we report the use of a tapered fluidized bed (TFB) for the preparation of multilayered polymer capsules. This is a significant improvement over our recent approach of fluidizing particles in cylindrical fluidized beds (CFB) for LbL assembly. We demonstrate that TFB is compatible with particles <3 μm in diameter (an order-of-magnitude improvement compared with CFB), which can be fluidized with minimal entrainment. Additionally, layering materials were expanded to include both electrostatic and hydrogen-bonding polymer pairs (e.g., poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS), and thiol-modified poly(methacrylic acid) (PMASH) and poly(N-vinylpyrrolidone) (PVPON), respectively). Finally, differences between capsules prepared via centrifugation-based and TFB LbL assembly were investigated. The obtained TFB microcapsules demonstrate increased film thickness and roughness compared with those prepared using centrifugation-based LbL assembly. Furthermore, PMASH microcapsules exhibit lower swelling and permeability when prepared via TFB LbL assembly compared with centrifugation-based LbL assembly due to enhanced multilayer deposition, entanglement, and cross-linking. Therefore, polymeric capsules fabricated via TFB LbL assembly may be useful for encapsulation and retention of relatively low molecular weight (∼20 kDa) hydrophilic biomacromolecules to passively or responsively release the payload for drug delivery applications. PMID:26651354

  16. Controlled surface functionality of magnetic nanoparticles by layer-by-layer assembled nano-films

    NASA Astrophysics Data System (ADS)

    Choi, Daheui; Son, Boram; Park, Tai Hyun; Hong, Jinkee

    2015-04-01

    Over the past several years, the preparation of functionalized nanoparticles has been aggressively pursued in order to develop desired structures, compositions, and structural order. Among the various nanoparticles, iron oxide magnetic nanoparticles (MNPs) have shown great promise because the material generated using these MNPs can be used in a variety of biomedical applications and possible bioactive functionalities. In this study, we report the development of various functionalized MNPs (F-MNPs) generated using the layer-by-layer (LbL) self-assembly method. To provide broad functional opportunities, we fabricated F-MNP bio-toolbox by using three different materials: synthetic polymers, natural polymers, and carbon materials. Each of these F-MNPs displays distinct properties, such as enhanced thickness or unique morphologies. In an effort to explore their biomedical applications, we generated basic fibroblast growth factor (bFGF)-loaded F-MNPs. The bFGF-loaded F-MNPs exhibited different release mechanisms and loading amounts, depending on the film material and composition order. Moreover, bFGF-loaded F-MNPs displayed higher biocompatibility and possessed superior proliferation properties than the bare MNPs and pure bFGF, respectively. We conclude that by simply optimizing the building materials and the nanoparticle's film composition, MNPs exhibiting various bioactive properties can be generated.Over the past several years, the preparation of functionalized nanoparticles has been aggressively pursued in order to develop desired structures, compositions, and structural order. Among the various nanoparticles, iron oxide magnetic nanoparticles (MNPs) have shown great promise because the material generated using these MNPs can be used in a variety of biomedical applications and possible bioactive functionalities. In this study, we report the development of various functionalized MNPs (F-MNPs) generated using the layer-by-layer (LbL) self-assembly method. To provide

  17. Automated biometric access control system for two-man-rule enforcement

    SciTech Connect

    Holmes, J.P.; Maxwell, R.L. ); Henderson, R.W. )

    1991-01-01

    This paper describes a limited access control system for nuclear facilities which makes use of the eye retinal identity verifier to control the passage of personnel into and out of one or a group of security controlled working areas. This access control system requires no keys, cards or credentials. The user simply enters his Personal Identification Number (PIN) and takes an eye reading to request passage. The PIN does not have to be kept secret. The system then relies on biometric identity verification of the user, along with other system information, to make the decision of whether or not to unlock the door. It also enforces multiple zones control with personnel tracking and the two-man-rule.

  18. Performance Evaluation of Virtualization Techniques for Control and Access of Storage Systems in Data Center Applications

    NASA Astrophysics Data System (ADS)

    Ahmadi, Mohammad Reza

    2013-09-01

    Virtualization is a new technology that creates virtual environments based on the existing physical resources. This article evaluates effect of virtualization techniques on control servers and access method in storage systems [1, 2]. In control server virtualization, we have presented a tile based evaluation based on heterogeneous workloads to compare several key parameters and demonstrate effectiveness of virtualization techniques. Moreover, we have evaluated the virtualized model using VMotion techniques and maximum consolidation. In access method, we have prepared three different scenarios using direct, semi-virtual, and virtual attachment models. We have evaluated the proposed models with several workloads including OLTP database, data streaming, file server, web server, etc. Results of evaluation for different criteria confirm that server virtualization technique has high throughput and CPU usage as well as good performance with noticeable agility. Also virtual technique is a successful alternative for accessing to the storage systems especially in large capacity systems. This technique can therefore be an effective solution for expansion of storage area and reduction of access time. Results of different evaluation and measurements demonstrate that the virtualization in control server and full virtual access provide better performance and more agility as well as more utilization in the systems and improve business continuity plan.

  19. Collaborative-Hybrid Multi-Layer Network Control for Emerging Cyber-Infrastructures

    SciTech Connect

    Lehman, Tom; Ghani, Nasir; Boyd, Eric

    2010-08-31

    At a high level, there were four basic task areas identified for the Hybrid-MLN project. They are: o Multi-Layer, Multi-Domain, Control Plane Architecture and Implementation, including OSCARS layer2 and InterDomain Adaptation, Integration of LambdaStation and Terapaths with Layer2 dynamic provisioning, Control plane software release, Scheduling, AAA, security architecture, Network Virtualization architecture, Multi-Layer Network Architecture Framework Definition; o Heterogeneous DataPlane Testing; o Simulation; o Project Publications, Reports, and Presentations.

  20. Accessibility to tuberculosis control services and tuberculosis programme performance in southern Ethiopia

    PubMed Central

    Dangisso, Mesay Hailu; Datiko, Daniel Gemechu; Lindtjørn, Bernt

    2015-01-01

    Background Despite the expansion of health services and community-based interventions in Ethiopia, limited evidence exists about the distribution of and access to health facilities and their relationship with the performance of tuberculosis (TB) control programmes. We aim to assess the geographical distribution of and physical accessibility to TB control services and their relationship with TB case notification rates (CNRs) and treatment outcome in the Sidama Zone, southern Ethiopia. Design We carried out an ecological study to assess physical accessibility to TB control facilities and the association of physical accessibility with TB CNRs and treatment outcome. We collected smear-positive pulmonary TB (PTB) cases treated during 2003–2012 from unit TB registers and TB service data such as availability of basic supplies for TB control and geographic locations of health services. We used ArcGIS 10.2 to measure the distance from each enumeration location to the nearest TB control facilities. A linear regression analysis was employed to assess factors associated with TB CNRs and treatment outcome. Results Over a decade the health service coverage (the health facility–to-population ratio) increased by 36% and the accessibility to TB control facilities also improved. Thus, the mean distance from TB control services was 7.6 km in 2003 (ranging from 1.8 to 25.5 km) between kebeles (the smallest administrative units) and had decreased to 3.2 km in 2012 (ranging from 1.5 to 12.4 km). In multivariate linear regression, as distance from TB diagnostic facilities (b-estimate=−0.25, p<0.001) and altitude (b-estimate=−0.31, p<0.001) increased, the CNRs of TB decreased, whereas a higher population density was associated with increased TB CNRs. Similarly, distance to TB control facilities (b-estimate=−0.27, p<0.001) and altitude (b-estimate=−0.30, p<0.001) were inversely associated with treatment success (proportion of treatment completed or cured cases). Conclusions

  1. Layers

    NASA Astrophysics Data System (ADS)

    Hong, K. J.; Jeong, T. S.; Youn, C. J.

    2014-09-01

    The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states Γ4( z), Γ5( x), and Γ5( y) to the conduction-band state Γ1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states Γ4( z), Γ5( x), and Γ5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

  2. A Study on Automated Context-aware Access Control Model Using Ontology

    NASA Astrophysics Data System (ADS)

    Jang, Bokman; Jang, Hyokyung; Choi, Euiin

    Applications in context-aware computing environment will be connected wireless network and various devices. According to, recklessness access of information resource can make trouble of system. So, access authority management is very important issue both information resource and adapt to system through founding security policy of needed system. But, existing security model is easy of approach to resource through simply user ID and password. This model has a problem that is not concerned about user's environment information. In this paper, propose model of automated context-aware access control using ontology that can more efficiently control about resource through inference and judgment of context information that collect user's information and user's environment context information in order to ontology modeling.

  3. Pace: Privacy-Protection for Access Control Enforcement in P2P Networks

    NASA Astrophysics Data System (ADS)

    Sánchez-Artigas, Marc; García-López, Pedro

    In open environments such as peer-to-peer (P2P) systems, the decision to collaborate with multiple users — e.g., by granting access to a resource — is hard to achieve in practice due to extreme decentralization and the lack of trusted third parties. The literature contains a plethora of applications in which a scalable solution for distributed access control is crucial. This fact motivates us to propose a protocol to enforce access control, applicable to networks consisting entirely of untrusted nodes. The main feature of our protocol is that it protects both sensitive permissions and sensitive policies, and does not rely on any centralized authority. We analyze the efficiency (computational effort and communication overhead) as well as the security of our protocol.

  4. Design of controlled release system with multi-layers of powder.

    PubMed

    Shimono, Norihito; Ueda, Masumi; Nakamura, Yasuhiko

    2002-09-01

    Pellets containing active ingredients were coated with water-insoluble powders, i.e. hydrogenated caster oil (Lubliwax (WAX)) and magnesium stearate (Mg-St). The influences of the structural difference of the sustained release layer and curing conditions on the drug release rate were investigated. Sodium valproate (VP-Na) was used as a highly water-soluble model drug. Drug release profiles were influenced by the combination of the WAX layer and the Mg-St layer. Even if the formula of sustained release layers were the same, drug release rate could be affected by the structural difference of the controlled release layer. The Mg-St layer was more effective in prolonging drug release than the WAX layer. Compared with single and double layer types, the triple layer (sandwich) type was most effective in obtaining a long sustained drug release. Heat-treatment retarded drug release mainly by increasing the density of the sustained release layer of the WAX. The Mg-St was effective in protecting the agglomeration between particles during heat-treatment. Optimal heat-treatment conditions were found to exist. Scanning electron microscopy (SEM) analysis indicated that heat-treatment caused the WAX to melt, formed a film-like structure and made the release layer dense. Furthermore, heat-treatment changed the release pattern of VP-Na from sustained release pellets with a multi-layer of powder, leading to zero-order release.

  5. Simulating the growth process of aromatic polyamide layer by monomer concentration controlling method

    NASA Astrophysics Data System (ADS)

    Jin, Yan; Liang, Songmiao; Wu, Zongce; Cai, Zhiqi; Zhao, Ning

    2014-09-01

    With the wide distribution and gradual increase of TMC concentration (CTMC) from 1 × 10-4 wt% to 2.5 × 10-1 wt%, the main purpose of this work is to simulate the surface structure and properties of polyamide layer of reverse osmosis membranes at its different growth stage. The surface structure and properties of the resulted membranes were then characterized by atomic force microscopy (AFM), scanning electron microscope (SEM), attenuated total reflectance infrared (ATR-IR) spectroscopy, drop shape analysis system and electrokinetic analyzer. The structure growth of polyamide layer underwent in turn three different stages including spherical aggregator, leaf-like and typical ridge-valley structure. Spherical aggregator is the intrinsic structure in the inner layer of polyamide while leaf-like structure is transitional on the outmost polyamide layer. Furthermore, to clarify the effect of the structure change on the properties of polyamide layer, contact angle and zeta potential in the surface of polyamide layer were studied. Hydrophilic surface of polyamide layer is accessible at higher TMC concentration because of the presence of negative charged groups. Performances of the membranes were further measured with an emphasis on studying its structure-performance relationship during the growth process of polyamide layer.

  6. Hysteresis-based congestion control at the B-ISDN access

    NASA Astrophysics Data System (ADS)

    Wissing, Johannes

    1993-11-01

    Multiplexing of bursty sources and refined congestion control strategies are still the subject of numerous research activities. Broadband applications with very high peak-to-mean bitrate ratio and long silence periods like still picture video gave rise to different ideas of rate control at the B-ISDN network access. Contributions on Input Rate Control for source coded traffic as well as on Server Rate Control within a LAN/ATM Interworking Unit have recently been presented. This paper addresses a congestion avoidance strategy at the network access regarding the aggregated traffic of bursty sources. Depending on the number of active sources as well as on certain defined congestion levels the cell rate at the network access is controlled. The proposed analytical approach is based on the model of uniform and continuous arrival and service. The selected underlying Markov chain contains `split' states in order to handle the congestion correlation. The proposed model is extended to an adaptive Non-Markov system where the buffer filling level is evaluated using a switching hysteresis. This type of congestion measurement turns out to be very useful for an adaptive rate control mechanism that guarantees a certain quality of service while still achieving a good statistical gain. The analytical approach is confirmed by results of a computer simulation that is extended to the more complex case of adaptive rate control.

  7. The need for the use of XACML access control policy in a distributed EHR and some performance considerations.

    PubMed

    Sucurovic, Snezana; Milutinovic, Veljko

    2008-01-01

    The Internet based distributed large scale information systems implements attribute based access control (ABAC) rather than Role Based Access Control (RBAC). The reason is that the Internet is identity less and that ABAC scales better. EXtensible Access Control Markup Language is standardized language for writing access control policies, access control requests and access control responses in ABAC. XACML can provide decentralized administration and credentials distribution. In year 2002 version of CEN ENV 13 606 attributes have been attached to EHCR components and in such a system ABAC and XACML have been easy to implement. This paper presents writing XACML policies in the case when attributes are in hierarchical structure. It is presented two possible solutions to write XACML policy in that case and that the solution when set functions are used is more compact and provides 10% better performances.

  8. Prevention and Control of Dental Disease through Improved Access to Comprehensive Care.

    ERIC Educational Resources Information Center

    American Dental Association, Chicago, IL.

    Prevention of dental disease is the key to improving the nation's oral health. The American Dental Association (ADA) program of prevention and control of dental disease through improved access to comprehensive care concentrates on those who have special difficulties in receiving care: the poor, the elderly, the handicapped, the institutionalized…

  9. A Stateful Multicast Access Control Mechanism for Future Metro-Area-Networks.

    ERIC Educational Resources Information Center

    Sun, Wei-qiang; Li, Jin-sheng; Hong, Pei-lin

    2003-01-01

    Multicasting is a necessity for a broadband metro-area-network; however security problems exist with current multicast protocols. A stateful multicast access control mechanism, based on MAPE, is proposed. The architecture of MAPE is discussed, as well as the states maintained and messages exchanged. The scheme is flexible and scalable. (Author/AEF)

  10. Mining Roles and Access Control for Relational Data under Privacy and Accuracy Constraints

    ERIC Educational Resources Information Center

    Pervaiz, Zahid

    2013-01-01

    Access control mechanisms protect sensitive information from unauthorized users. However, when sensitive information is shared and a Privacy Protection Mechanism (PPM) is not in place, an authorized insider can still compromise the privacy of a person leading to identity disclosure. A PPM can use suppression and generalization to anonymize and…

  11. 77 FR 26789 - Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-07

    ... violation of section 337 in the infringement of certain patents. 73 FR 75131. The principal respondent was... order. 75 FR 44989-90 (July 30, 2010). The Commission also issued cease and desist orders against those... COMMISSION Certain Semiconductor Chips Having Synchronous Dynamic Random Access Memory Controllers...

  12. Predicting Health Care Utilization among Latinos: Health Locus of Control Beliefs or Access Factors?

    ERIC Educational Resources Information Center

    De Jesus, Maria; Xiao, Chenyang

    2014-01-01

    There are two competing research explanations to account for Latinos' underutilization of health services relative to non-Latino Whites in the United States. One hypothesis examines the impact of health locus of control (HLOC) beliefs, while the other focuses on the role of access factors on health care use. To date, the relative strength of…

  13. An Annotated and Cross-Referenced Bibliography on Computer Security and Access Control in Computer Systems.

    ERIC Educational Resources Information Center

    Bergart, Jeffrey G.; And Others

    This paper represents a careful study of published works on computer security and access control in computer systems. The study includes a selective annotated bibliography of some eighty-five important published results in the field and, based on these papers, analyzes the state of the art. In annotating these works, the authors try to be…

  14. 75 FR 47464 - Exemption to Prohibition on Circumvention of Copyright Protection Systems for Access Control...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-06

    ... Copyright Office 37 CFR Part 201 Exemption to Prohibition on Circumvention of Copyright Protection Systems for Access Control Technologies AGENCY: Copyright Office, Library of Congress. ACTION: Final Rule; correction. SUMMARY: The Copyright Office makes a nonsubstantial correction to its regulation announcing...

  15. 36 CFR 1256.70 - What controls access to national security-classified information?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... materials; 44 U.S.C. 2111, 44 U.S.C. 2201 et seq., and 36 CFR part 1270 for Presidential records; and 44 U.S.C. 2111 note and 36 CFR part 1275 for Nixon Presidential materials. ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false What controls access...

  16. Secure Access Control and Large Scale Robust Representation for Online Multimedia Event Detection

    PubMed Central

    Liu, Changyu; Li, Huiling

    2014-01-01

    We developed an online multimedia event detection (MED) system. However, there are a secure access control issue and a large scale robust representation issue when we want to integrate traditional event detection algorithms into the online environment. For the first issue, we proposed a tree proxy-based and service-oriented access control (TPSAC) model based on the traditional role based access control model. Verification experiments were conducted on the CloudSim simulation platform, and the results showed that the TPSAC model is suitable for the access control of dynamic online environments. For the second issue, inspired by the object-bank scene descriptor, we proposed a 1000-object-bank (1000OBK) event descriptor. Feature vectors of the 1000OBK were extracted from response pyramids of 1000 generic object detectors which were trained on standard annotated image datasets, such as the ImageNet dataset. A spatial bag of words tiling approach was then adopted to encode these feature vectors for bridging the gap between the objects and events. Furthermore, we performed experiments in the context of event classification on the challenging TRECVID MED 2012 dataset, and the results showed that the robust 1000OBK event descriptor outperforms the state-of-the-art approaches. PMID:25147840

  17. Secure access control and large scale robust representation for online multimedia event detection.

    PubMed

    Liu, Changyu; Lu, Bin; Li, Huiling

    2014-01-01

    We developed an online multimedia event detection (MED) system. However, there are a secure access control issue and a large scale robust representation issue when we want to integrate traditional event detection algorithms into the online environment. For the first issue, we proposed a tree proxy-based and service-oriented access control (TPSAC) model based on the traditional role based access control model. Verification experiments were conducted on the CloudSim simulation platform, and the results showed that the TPSAC model is suitable for the access control of dynamic online environments. For the second issue, inspired by the object-bank scene descriptor, we proposed a 1000-object-bank (1000OBK) event descriptor. Feature vectors of the 1000OBK were extracted from response pyramids of 1000 generic object detectors which were trained on standard annotated image datasets, such as the ImageNet dataset. A spatial bag of words tiling approach was then adopted to encode these feature vectors for bridging the gap between the objects and events. Furthermore, we performed experiments in the context of event classification on the challenging TRECVID MED 2012 dataset, and the results showed that the robust 1000OBK event descriptor outperforms the state-of-the-art approaches.

  18. Control of Access to Memory: The Use of Task Interference as a Behavioral Probe

    ERIC Educational Resources Information Center

    Loft, Shayne; Humphreys, Michael S.; Whitney, Susannah J.

    2008-01-01

    Directed forgetting and prospective memory methods were combined to examine differences in the control of memory access. Between studying two lists of target words, participants were either instructed to forget the first list, or to continue remembering the first list. After study participants performed a lexical decision task with an additional…

  19. The Role of Automatic Indexing in Access Control: A Modular View

    ERIC Educational Resources Information Center

    Hartson, H. Rex

    1974-01-01

    A model which relates the access control and indexing functions. The model is based on concept protection which allows a practically unbounded number of levels (subsets) of protection without requiring a fixed hierarchy among the levels. This protection is offered independently for each of the user operations allowed. (Author)

  20. 50 CFR 648.92 - Effort-control program for monkfish limited access vessels.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Effort-control program for monkfish limited access vessels. 648.92 Section 648.92 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT... UNITED STATES Management Measures for the NE Multispecies and Monkfish Fisheries § 648.92...

  1. An Access Control and Trust Management Framework for Loosely-Coupled Multidomain Environments

    ERIC Educational Resources Information Center

    Zhang, Yue

    2010-01-01

    Multidomain environments where multiple organizations interoperate with each other are becoming a reality as can be seen in emerging Internet-based enterprise applications. Access control to ensure secure interoperation in such an environment is a crucial challenge. A multidomain environment can be categorized as "tightly-coupled" and…

  2. The Use of Passwords for Controlled Access to Computer Resources. Computer Science & Technology.

    ERIC Educational Resources Information Center

    Wood, Helen M.

    This paper considers the generation of passwords and their effective application to the problem of controlling access to computer resources. After describing the need for and uses of passwords, password schemes are categorized according to selection technique, lifetime, physical characteristics, and information content. Password protection, both…

  3. Fast access control of the head positioning using a digital signal processor

    NASA Astrophysics Data System (ADS)

    Hasegawa, Susumu; Mizoshita, Yoshifumi; Ueno, Takahisa; Takaishi, Kazuhiko

    1990-08-01

    We have developed a new digital servo controller for a 5"hard disk drive which has average access time of 10 ms for a 25 mm stroke. To obtain this fast access speed, we used a state estimator with a new acceleration irajectory model. The estimator and trajectory generator are implemented using a digital signal processor. There are two problems for fast access control: motor coil inductance and the mechanical resonance of the actuator and disk enclosure. To solve these problems and to achieve precise head positioning, we developed the following control method. To solve the voice coil motor inductance and actuator resonance problems, we used a new acceleration trajectory model which is not affected by the coil inductance when the head moves quickly. This design is based on an optinial control theory which minimizes the square of differentiated acceleration. By using this new trajectory model, the high harmonics of actuator drive are damped and the residual vibration ofactuator immediately after access is decreased.

  4. Functional requirements with survey results for integrated intrusion detection and access control annunciator systems

    SciTech Connect

    Arakaki, L.H.; Monaco, F.M.

    1995-09-01

    This report contains the guidance Functional Requirements for an Integrated Intrusion Detection and Access Control Annunciator System, and survey results of selected commercial systems. The survey questions were based upon the functional requirements; therefore, the results reflect which and sometimes how the guidance recommendations were met.

  5. 21 CFR 1311.125 - Requirements for establishing logical access control-Individual practitioner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... least one of the individuals designated under paragraph (a) of this section must verify that the DEA... authentication credential to satisfy the logical access controls. The second individual must be a DEA registrant... practitioner's DEA registration expires, unless the registration has been renewed. (3) The...

  6. 21 CFR 1311.125 - Requirements for establishing logical access control-Individual practitioner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... least one of the individuals designated under paragraph (a) of this section must verify that the DEA... authentication credential to satisfy the logical access controls. The second individual must be a DEA registrant... practitioner's DEA registration expires, unless the registration has been renewed. (3) The...

  7. 21 CFR 1311.125 - Requirements for establishing logical access control-Individual practitioner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... least one of the individuals designated under paragraph (a) of this section must verify that the DEA... authentication credential to satisfy the logical access controls. The second individual must be a DEA registrant... practitioner's DEA registration expires, unless the registration has been renewed. (3) The...

  8. 21 CFR 1311.125 - Requirements for establishing logical access control-Individual practitioner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... least one of the individuals designated under paragraph (a) of this section must verify that the DEA... authentication credential to satisfy the logical access controls. The second individual must be a DEA registrant... practitioner's DEA registration expires, unless the registration has been renewed. (3) The...

  9. An enhancement of the role-based access control model to facilitate information access management in context of team collaboration and workflow.

    PubMed

    Le, Xuan Hung; Doll, Terry; Barbosu, Monica; Luque, Amneris; Wang, Dongwen

    2012-12-01

    Although information access control models have been developed and applied to various applications, few of the previous works have addressed the issue of managing information access in the combined context of team collaboration and workflow. To facilitate this requirement, we have enhanced the Role-Based Access Control (RBAC) model through formulating universal constraints, defining bridging entities and contributing attributes, extending access permissions to include workflow contexts, synthesizing a role-based access delegation model to target on specific objects, and developing domain ontologies as instantiations of the general model to particular applications. We have successfully applied this model to the New York State HIV Clinical Education Initiative (CEI) project to address the specific needs of information management in collaborative processes. An initial evaluation has shown this model achieved a high level of agreement with an existing system when applied to 4576 cases (kappa=0.801). Comparing to a reference standard, the sensitivity and specificity of the enhanced RBAC model were at the level of 97-100%. These results indicate that the enhanced RBAC model can be effectively used for information access management in context of team collaboration and workflow to coordinate clinical education programs. Future research is required to incrementally develop additional types of universal constraints, to further investigate how the workflow context and access delegation can be enriched to support the various needs on information access management in collaborative processes, and to examine the generalizability of the enhanced RBAC model for other applications in clinical education, biomedical research, and patient care.

  10. Hydration Layer of Enzymes Partially Controls Conformational Dynamics

    NASA Astrophysics Data System (ADS)

    Alavi, Zahra; Zocchi Team

    2015-03-01

    For a typical (20 kD, 4 nm size) monomeric enzyme, more than 50% of the residues are at the surface. The mechanics of these soft, heterogeneous nanoparticles was recently shown to be viscoelastic. Here we explore the contribution of the enzyme's surface to the mechanics of the molecule. Nano-rheology provides sub-?angstrom resolution measurements of the reversible deformation of the enzyme subject to an oscillatory mechanical stress. We perturb the surface of the enzyme by adding small amounts of DMSO, believed to affect ordering of the enzyme - water interface. We observe a dramatic though reversible change in the mechanics of the enzyme, which becomes more viscous. On the other hand, the catalytic speed is unaffected, while at higher DMSO concentrations (>1 %) it even increases. Our measurements show that small (<1 %) bulk concentrations of DMSO, which have negligible effect on the physico-chemical properties of bulk water, including the viscosity and dielectric constant, have nonetheless dramatic effect on the dynamics of the hydration layer of the enzyme, and ultimately on the enzyme's mechanics. DMSO accumulates in the hydration layer (``binds to the surface of the enzyme''). Apparently the order - inducing (``kosmotropic'') quality of DMSO leads to a hardening of the enzyme - water interface. US-Israel Binational Science Foundation.

  11. Controllable layer-by-layer assembly of PVA and phenylboronic acid-derivatized chitosan.

    PubMed

    Zhang, Dan; Yu, Guanghua; Long, Zhu; Yang, Guihua; Wang, Bin

    2016-04-20

    Phenylboronic acid-derivatized chitosan (chitosan-PBA) were prepared by grafting small molecules bearing phenylboronic acid groups onto chitosan with N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) as a coupling reagent pair. Self-assembly multilayer thin films of chitosan-PBA and poly(vinyl alcohol) were subsequently produced under pH control on supporting surfaces, either a silicon wafer or polystyrene latex particles. The driving force of the self-assembly was the ester formation of phenylboronic acid containing polymers with PVA, which can be "turned off" by simple pH control. PMID:26876848

  12. Adaptive dual-layer super-twisting control and observation

    NASA Astrophysics Data System (ADS)

    Edwards, Christopher; Shtessel, Yuri

    2016-09-01

    In this paper, a super-twisting-like structure with adaptive gains is proposed. The structure is parameterised by two scalar gains, both of which adapt, and by an additional time-varying term. The magnitudes of the adaptive terms are allowed to both increase and decrease as appropriate so that they are as small as possible, in the sense that they do not unnecessarily over-bound the uncertainty, and yet are large enough to sustain a sliding motion. In the paper, a new time varying gain is incorporated into the traditional super-twisting architecture. The proposed adaption law has a dual-layer structure which is formally analyzed using Lyapunov techniques. The additional term has the effect of simplifying the stability analysis whilst guaranteeing the second-order sliding mode properties of the traditional super-twisting scheme.

  13. Demonstration of Symmetry Control of Infrared Heated Deuterium Layers in Hohlraums

    SciTech Connect

    Koziozieski, B J; London, R A; McEachern, R L; Bittner, D N

    2003-08-22

    Infrared smoothed deuterium ice layers inside capsules have been successfully demonstrated for capsules inside cylindrical hohlraums. Improved characterization methods and infrared illumination enables low mode control in both the axial and azimuthal directions. Experimental results agree well with computer models. Results of these experiments will be used to derive accuracy requirements for an infrared heating system for ice layers in hohlraums on NIF.

  14. Control and reduction of unsteady pressure loads in separated shock wave turbulent boundary layer interaction

    NASA Technical Reports Server (NTRS)

    Dolling, David S.; Barter, John W.

    1995-01-01

    The focus was on developing means of controlling and reducing unsteady pressure loads in separated shock wave turbulent boundary layer interactions. Section 1 describes how vortex generators can be used to effectively reduce loads in compression ramp interaction, while Section 2 focuses on the effects of 'boundary-layer separators' on the same interaction.

  15. Accessibility of dog populations for rabies control in Kathmandu valley, Nepal.

    PubMed Central

    Bögel, K.; Joshi, D. D.

    1990-01-01

    The accessibility of dogs in urban areas of Kathmandu valley was measured using the following approaches: determination of the proportion of dogs that bore signs of having been the objects of religious worship and other signs of household association, supplemented by information obtained by interviewing people in the neighbourhood; and the vaccination coverage attained in a rabies control campaign that was preceded by intensive activities to encourage the community to participate. An accessibility rate of 90-95% was determined using the first of these approaches, whereas 75-80% of the total dog population was reached in the vaccination campaign. PMID:2289296

  16. Access Scheme for Controlling Mobile Agents and its Application to Share Medical Information.

    PubMed

    Liao, Yu-Ting; Chen, Tzer-Shyong; Chen, Tzer-Long; Chung, Yu-Fang; Chen, Yu- Xin; Hwang, Jen-Hung; Wang, Huihui; Wei, Wei

    2016-05-01

    This study is showing the advantage of mobile agents to conquer heterogeneous system environments and contribute to a virtual integrated sharing system. Mobile agents will collect medical information from each medical institution as a method to achieve the medical purpose of data sharing. Besides, this research also provides an access control and key management mechanism by adopting Public key cryptography and Lagrange interpolation. The safety analysis of the system is based on a network attacker's perspective. The achievement of this study tries to improve the medical quality, prevent wasting medical resources and make medical resources access to appropriate configuration. PMID:27010391

  17. Multi-layer neural networks for robot control

    NASA Technical Reports Server (NTRS)

    Pourboghrat, Farzad

    1989-01-01

    Two neural learning controller designs for manipulators are considered. The first design is based on a neural inverse-dynamics system. The second is the combination of the first one with a neural adaptive state feedback system. Both types of controllers enable the manipulator to perform any given task very well after a period of training and to do other untrained tasks satisfactorily. The second design also enables the manipulator to compensate for unpredictable perturbations.

  18. Active/Passive Control of Sound Radiation from Panels using Constrained Layer Damping

    NASA Technical Reports Server (NTRS)

    Gibbs, Gary P.; Cabell, Randolph H.

    2003-01-01

    A hybrid passive/active noise control system utilizing constrained layer damping and model predictive feedback control is presented. This system is used to control the sound radiation of panels due to broadband disturbances. To facilitate the hybrid system design, a methodology for placement of constrained layer damping which targets selected modes based on their relative radiated sound power is developed. The placement methodology is utilized to determine two constrained layer damping configurations for experimental evaluation of a hybrid system. The first configuration targets the (4,1) panel mode which is not controllable by the piezoelectric control actuator, and the (2,3) and (5,2) panel modes. The second configuration targets the (1,1) and (3,1) modes. The experimental results demonstrate the improved reduction of radiated sound power using the hybrid passive/active control system as compared to the active control system alone.

  19. A Simple Approach for Molecular Controlled Release based on Atomic Layer Deposition Hybridized Organic-Inorganic Layers

    NASA Astrophysics Data System (ADS)

    Boehler, Christian; Güder, Firat; Kücükbayrak, Umut M.; Zacharias, Margit; Asplund, Maria

    2016-01-01

    On-demand release of bioactive substances with high spatial and temporal control offers ground-breaking possibilities in the field of life sciences. However, available strategies for developing such release systems lack the possibility of combining efficient control over release with adequate storage capability in a reasonably compact system. In this study we present a new approach to target this deficiency by the introduction of a hybrid material. This organic-inorganic material was fabricated by atomic layer deposition of ZnO into thin films of polyethylene glycol, forming the carrier matrix for the substance to be released. Sub-surface growth mechanisms during this process converted the liquid polymer into a solid, yet water-soluble, phase. This layer permits extended storage for various substances within a single film of only a few micrometers in thickness, and hence demands minimal space and complexity. Improved control over release of the model substance Fluorescein was achieved by coating the hybrid material with a conducting polymer film. Single dosage and repetitive dispensing from this system was demonstrated. Release was controlled by applying a bias potential of ±0.5 V to the polymer film enabling or respectively suppressing the expulsion of the model drug. In vitro tests showed excellent biocompatibility of the presented system.

  20. A Simple Approach for Molecular Controlled Release based on Atomic Layer Deposition Hybridized Organic-Inorganic Layers

    PubMed Central

    Boehler, Christian; Güder, Firat; Kücükbayrak, Umut M.; Zacharias, Margit; Asplund, Maria

    2016-01-01

    On-demand release of bioactive substances with high spatial and temporal control offers ground-breaking possibilities in the field of life sciences. However, available strategies for developing such release systems lack the possibility of combining efficient control over release with adequate storage capability in a reasonably compact system. In this study we present a new approach to target this deficiency by the introduction of a hybrid material. This organic-inorganic material was fabricated by atomic layer deposition of ZnO into thin films of polyethylene glycol, forming the carrier matrix for the substance to be released. Sub-surface growth mechanisms during this process converted the liquid polymer into a solid, yet water-soluble, phase. This layer permits extended storage for various substances within a single film of only a few micrometers in thickness, and hence demands minimal space and complexity. Improved control over release of the model substance Fluorescein was achieved by coating the hybrid material with a conducting polymer film. Single dosage and repetitive dispensing from this system was demonstrated. Release was controlled by applying a bias potential of ±0.5 V to the polymer film enabling or respectively suppressing the expulsion of the model drug. In vitro tests showed excellent biocompatibility of the presented system. PMID:26791399

  1. Controlled-release fertilizer composition substantially coated with an impermeable layer

    DOEpatents

    Ankeny, Mark

    2016-03-29

    A controlled-release fertilizer composition is provided that is substantially coated with an impermeable layer. The fertilizer composition may further include one or more hollow sections to allow for root penetration and efficient delivery of nutrients.

  2. Scalable control program for multiprecursor flow-type atomic layer deposition system

    SciTech Connect

    Selvaraj, Sathees Kannan; Takoudis, Christos G.

    2015-01-01

    The authors report the development and implementation of a scalable control program to control flow type atomic layer deposition (ALD) reactor with multiple precursor delivery lines. The program logic is written and tested in LABVIEW environment to control ALD reactor with four precursor delivery lines to deposit up to four layers of different materials in cyclic manner. The programming logic is conceived such that to facilitate scale up for depositing more layers with multiple precursors and scale down for using single layer with any one precursor in the ALD reactor. The program takes precursor and oxidizer exposure and purging times as input and controls the sequential opening and closing of the valves to facilitate the complex ALD process in cyclic manner. The program could be used to deposit materials from any single line or in tandem with other lines in any combination and in any sequence.

  3. Controlled selforganization of atom vacancies in monatomic gallium layers

    SciTech Connect

    Snijders, Paul C; Moon, Eun Ju; Gonzalez, C.; Ortega, J.; Flores, F.; Weitering, Harm H

    2007-01-01

    Ga adsorption on the Si(112) surface results in the formation of pseudomorphic Ga atom chains. Compressive strain in these atom chains is relieved via creation of adatom vacancies and their selforganization into meandering vacancy lines. The average spacing between these line defects can be controlled, within limits, by adjusting the chemical potential of the Ga adatoms. We derive a lattice model that quantitatively connects density functional theory (DFT) calculations for perfectly ordered structures with the fluctuating disorder seen in experiment and the experimental control parameter. This hybrid approach of lattice modeling and DFT can be applied to other examples of line defects in heteroepitaxy.

  4. Layer-specific cholinergic control of human and mouse cortical synaptic plasticity.

    PubMed

    Verhoog, Matthijs B; Obermayer, Joshua; Kortleven, Christian A; Wilbers, René; Wester, Jordi; Baayen, Johannes C; De Kock, Christiaan P J; Meredith, Rhiannon M; Mansvelder, Huibert D

    2016-01-01

    Individual cortical layers have distinct roles in information processing. All layers receive cholinergic inputs from the basal forebrain (BF), which is crucial for cognition. Acetylcholinergic receptors are differentially distributed across cortical layers, and recent evidence suggests that different populations of BF cholinergic neurons may target specific prefrontal cortical (PFC) layers, raising the question of whether cholinergic control of the PFC is layer dependent. Here we address this issue and reveal dendritic mechanisms by which endogenous cholinergic modulation of synaptic plasticity is opposite in superficial and deep layers of both mouse and human neocortex. Our results show that in different cortical layers, spike timing-dependent plasticity is oppositely regulated by the activation of nicotinic acetylcholine receptors (nAChRs) either located on dendrites of principal neurons or on GABAergic interneurons. Thus, layer-specific nAChR expression allows functional layer-specific control of cortical processing and plasticity by the BF cholinergic system, which is evolutionarily conserved from mice to humans. PMID:27604129

  5. Layer-specific cholinergic control of human and mouse cortical synaptic plasticity

    PubMed Central

    Verhoog, Matthijs B.; Obermayer, Joshua; Kortleven, Christian A.; Wilbers, René; Wester, Jordi; Baayen, Johannes C.; De Kock, Christiaan P. J.; Meredith, Rhiannon M.; Mansvelder, Huibert D.

    2016-01-01

    Individual cortical layers have distinct roles in information processing. All layers receive cholinergic inputs from the basal forebrain (BF), which is crucial for cognition. Acetylcholinergic receptors are differentially distributed across cortical layers, and recent evidence suggests that different populations of BF cholinergic neurons may target specific prefrontal cortical (PFC) layers, raising the question of whether cholinergic control of the PFC is layer dependent. Here we address this issue and reveal dendritic mechanisms by which endogenous cholinergic modulation of synaptic plasticity is opposite in superficial and deep layers of both mouse and human neocortex. Our results show that in different cortical layers, spike timing-dependent plasticity is oppositely regulated by the activation of nicotinic acetylcholine receptors (nAChRs) either located on dendrites of principal neurons or on GABAergic interneurons. Thus, layer-specific nAChR expression allows functional layer-specific control of cortical processing and plasticity by the BF cholinergic system, which is evolutionarily conserved from mice to humans. PMID:27604129

  6. Computer vector multiprocessing control with multiple access memory and priority conflict resolution method

    SciTech Connect

    Chen, S.S.; Schiffleger, A.J.

    1990-02-13

    This patent describes a multiprocessor memory system. It comprises: a central memory comprised of a plurality of independently addressable memory banks organized into a plurality of sections each accessible through a plurality of access paths; a plurality of processing machines; each of the processing machine including a plurality of ports for generating memory references to any one of the central memory sections; and conflict resolution means interfacing each of the ports to each of the central memory sections through the central memory access paths. The resolution means for receiving references from the ports and coordinating and controlling the procession of the references along to the access paths. The conflict resolution means comprising a plurality of conflict resolution circuits corresponding in number to the memory sections, each of the circuits receiving the references to its corresponding section from any one of the ports and selectively conveying the references to the access paths for the corresponding section. The circuits each including; means for checking the readiness of the memory banks to be referenced and holding a reference to a busy one of the banks until the bank is ready to be referenced; means for detecting when more than one of the references is pending to the same bank simultaneously and holding all but one of the simultaneously pending references; and means communicating with the ports and the other of the conflict resolution circuits to cause one of the ports referencing the memory to suspend generation of further references when a reference from the referencing port is being held.

  7. Reducing operation voltages by introducing a low-k switching layer in indium–tin-oxide-based resistance random access memory

    NASA Astrophysics Data System (ADS)

    Jin, Fu-Yuan; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Pan, Chih-Hung; Lin, Chih-Yang; Chen, Po-Hsun; Chen, Min-Chen; Huang, Hui-Chun; Lo, Ikai; Zheng, Jin-Cheng; Sze, Simon M.

    2016-06-01

    In this letter, we inserted a low dielectric constant (low-k) or high dielectric constant (high-k) material as a switching layer in indium–tin-oxide-based resistive random-access memory. After measuring the two samples, we found that the low-k material device has very low operating voltages (‑80 and 110 mV for SET and RESET operations, respectively). Current fitting results were then used with the COMSOL software package to simulate electric field distribution in the layers. After combining the electrical measurement results with simulations, a conduction model was proposed to explain resistance switching behaviors in the two structures.

  8. Reducing operation voltages by introducing a low-k switching layer in indium-tin-oxide-based resistance random access memory

    NASA Astrophysics Data System (ADS)

    Jin, Fu-Yuan; Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Pan, Chih-Hung; Lin, Chih-Yang; Chen, Po-Hsun; Chen, Min-Chen; Huang, Hui-Chun; Lo, Ikai; Zheng, Jin-Cheng; Sze, Simon M.

    2016-06-01

    In this letter, we inserted a low dielectric constant (low-k) or high dielectric constant (high-k) material as a switching layer in indium-tin-oxide-based resistive random-access memory. After measuring the two samples, we found that the low-k material device has very low operating voltages (-80 and 110 mV for SET and RESET operations, respectively). Current fitting results were then used with the COMSOL software package to simulate electric field distribution in the layers. After combining the electrical measurement results with simulations, a conduction model was proposed to explain resistance switching behaviors in the two structures.

  9. Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

    DOEpatents

    Repins, Ingrid L.; Kuciauskas, Darius

    2015-07-07

    A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

  10. Controlled Exfoliation of Layered Silicate Heterostructures into Bilayers and Their Conversion into Giant Janus Platelets.

    PubMed

    Stöter, Matthias; Gödrich, Sebastian; Feicht, Patrick; Rosenfeldt, Sabine; Thurn, Herbert; Neubauer, Jens W; Seuss, Maximilian; Lindner, Peter; Kalo, Hussein; Möller, Michael; Fery, Andreas; Förster, Stephan; Papastavrou, Georg; Breu, Josef

    2016-06-20

    Ordered heterostructures of layered materials where interlayers with different reactivities strictly alternate in stacks offer predetermined slippage planes that provide a precise route for the preparation of bilayer materials. We use this route for the synthesis of a novel type of reinforced layered silicate bilayer that is 15 % stiffer than the corresponding monolayer. Furthermore, we will demonstrate that triggering cleavage of bilayers by osmotic swelling gives access to a generic toolbox for an asymmetrical modification of the two vis-à-vis standing basal planes of monolayers. Only two simple steps applying arbitrary commercial polycations are needed to obtain such Janus-type monolayers. The generic synthesis route will be applicable to many other layered compounds capable of osmotic swelling, rendering this approach interesting for a variety of materials and applications. PMID:27140654

  11. Controlled Access Headings in EAD Finding Aids: Current Practices in Number of and Types of Headings Assigned

    ERIC Educational Resources Information Center

    Mascaro, Michelle

    2011-01-01

    This article presents the findings from a study of controlled access headings assigned to encoded archival description finding aids in the Ohio Library and Information Network Finding Aid Repository, focusing on the number of headings per finding aid and the category of terms assigned. Assigning multiple controlled access headings was widely…

  12. Differential domain accessibility to monoclonal antibodies in three different morphological assemblies built up by the S-layer protein of Thermus thermophilus HB8.

    PubMed Central

    Castón, J R; Olabarría, G; Lasa, I; Carrascosa, J L; Berenguer, J

    1996-01-01

    A collection of 27 monoclonal antibodies (MAbs) against the S-layer protein (P100) of Thermus thermophilus HB8 has been obtained. They have been classified according to their ability to recognize S-layer regions expressed in E. coli from plasmids containing different fragments of its coding gene, slpA. The accessibility of the binding sites in hexagonal, trigonal, or tetragonal assemblies of P100 was analyzed by enzyme-linked immunosorbent assays with six of these MAbs and their respective Fab fragments. When packed hexagonally as the native S-layer (S1 assemblies), only a small region located near the amino terminus of the P1OO was accessible. However, when P1OO was assembled into trigonal (pS2 assemblies) or tetragonal (S2 assemblies) arrays, most of the protein domains analyzed were easily detected, thus suggesting that P1OO is assembled in S2 and pS2 in a similar way and that these two arrangements are quite different from the S1 assembly. Relationships between accessibility and sequence predictions are discussed. PMID:8655568

  13. An Internet of Things Example: Classrooms Access Control over Near Field Communication

    PubMed Central

    Palma, Daniel; Agudo, Juan Enrique; Sánchez, Héctor; Macías, Miguel Macías

    2014-01-01

    The Internet of Things is one of the ideas that has become increasingly relevant in recent years. It involves connecting things to the Internet in order to retrieve information from them at any time and from anywhere. In the Internet of Things, sensor networks that exchange information wirelessly via Wi-Fi, Bluetooth, Zigbee or RF are common. In this sense, our paper presents a way in which each classroom control is accessed through Near Field Communication (NFC) and the information is shared via radio frequency. These data are published on the Web and could easily be used for building applications from the data collected. As a result, our application collects information from the classroom to create a control classroom tool that displays access to and the status of all the classrooms graphically and also connects this data with social networks. PMID:24755520

  14. An internet of things example: classrooms access control over near field communication.

    PubMed

    Palma, Daniel; Agudo, Juan Enrique; Sánchez, Héctor; Macías, Miguel Macías

    2014-04-21

    The Internet of Things is one of the ideas that has become increasingly relevant in recent years. It involves connecting things to the Internet in order to retrieve information from them at any time and from anywhere. In the Internet of Things, sensor networks that exchange information wirelessly via Wi-Fi, Bluetooth, Zigbee or RF are common. In this sense, our paper presents a way in which each classroom control is accessed through Near Field Communication (NFC) and the information is shared via radio frequency. These data are published on the Web and could easily be used for building applications from the data collected. As a result, our application collects information from the classroom to create a control classroom tool that displays access to and the status of all the classrooms graphically and also connects this data with social networks.

  15. A threat intelligence framework for access control security in the oil industry

    NASA Astrophysics Data System (ADS)

    Alaskandrani, Faisal T.

    The research investigates the problem raised by the rapid development in the technology industry giving security concerns in facilities built by the energy industry containing diverse platforms. The difficulty of continuous updates to network security architecture and assessment gave rise to the need to use threat intelligence frameworks to better assess and address networks security issues. Focusing on access control security to the ICS and SCADA systems that is being utilized to carry out mission critical and life threatening operations. The research evaluates different threat intelligence frameworks that can be implemented in the industry seeking the most suitable and applicable one that address the issue and provide more security measures. The validity of the result is limited to the same environment that was researched as well as the technologies being utilized. The research concludes that it is possible to utilize a Threat Intelligence framework to prioritize security in Access Control Measures in the Oil Industry.

  16. A Privacy Access Control Framework for Web Services Collaboration with Role Mechanisms

    NASA Astrophysics Data System (ADS)

    Liu, Linyuan; Huang, Zhiqiu; Zhu, Haibin

    With the popularity of Internet technology, web services are becoming the most promising paradigm for distributed computing. This increased use of web services has meant that more and more personal information of consumers is being shared with web service providers, leading to the need to guarantee the privacy of consumers. This paper proposes a role-based privacy access control framework for Web services collaboration, it utilizes roles to specify the privacy privileges of services, and considers the impact on the reputation degree of the historic experience of services in playing roles. Comparing to the traditional privacy access control approaches, this framework can make the fine-grained authorization decision, thus efficiently protecting consumers' privacy.

  17. Ver-i-Fus: an integrated access control and information monitoring and management system

    NASA Astrophysics Data System (ADS)

    Thomopoulos, Stelios C.; Reisman, James G.; Papelis, Yiannis E.

    1997-01-01

    This paper describes the Ver-i-Fus Integrated Access Control and Information Monitoring and Management (IAC-I2M) system that INTELNET Inc. has developed. The Ver-i-Fus IAC-I2M system has been designed to meet the most stringent security and information monitoring requirements while allowing two- way communication between the user and the system. The systems offers a flexible interface that permits to integrate practically any sensing device, or combination of sensing devices, including a live-scan fingerprint reader, thus providing biometrics verification for enhanced security. Different configurations of the system provide solutions to different sets of access control problems. The re-configurable hardware interface, tied together with biometrics verification and a flexible interface that allows to integrate Ver-i-Fus with an MIS, provide an integrated solution to security, time and attendance, labor monitoring, production monitoring, and payroll applications.

  18. Improving the prediction accuracy of residue solvent accessibility and real-value backbone torsion angles of proteins by guided-learning through a two-layer neural network.

    PubMed

    Faraggi, Eshel; Xue, Bin; Zhou, Yaoqi

    2009-03-01

    This article attempts to increase the prediction accuracy of residue solvent accessibility and real-value backbone torsion angles of proteins through improved learning. Most methods developed for improving the backpropagation algorithm of artificial neural networks are limited to small neural networks. Here, we introduce a guided-learning method suitable for networks of any size. The method employs a part of the weights for guiding and the other part for training and optimization. We demonstrate this technique by predicting residue solvent accessibility and real-value backbone torsion angles of proteins. In this application, the guiding factor is designed to satisfy the intuitive condition that for most residues, the contribution of a residue to the structural properties of another residue is smaller for greater separation in the protein-sequence distance between the two residues. We show that the guided-learning method makes a 2-4% reduction in 10-fold cross-validated mean absolute errors (MAE) for predicting residue solvent accessibility and backbone torsion angles, regardless of the size of database, the number of hidden layers and the size of input windows. This together with introduction of two-layer neural network with a bipolar activation function leads to a new method that has a MAE of 0.11 for residue solvent accessibility, 36 degrees for psi, and 22 degrees for phi. The method is available as a Real-SPINE 3.0 server in http://sparks.informatics.iupui.edu.

  19. Turbulent boundary-layer control with spanwise travelling waves

    NASA Astrophysics Data System (ADS)

    Whalley, Richard D.; Choi, Kwing-So

    2011-12-01

    It has been demonstrated through numerical simulations using Lorentz forcing that spanwise travelling waves on turbulent wall flows can lead to a skin-friction drag reduction on the order of 30%. As an aeronautical application of this innovative flow control technique, we have investigated into the use of Dielectric-Barrier-Discharge (DBD) plasma actuators to generate spanwise travelling waves in air. The near-wall structures modified by the spanwise travelling waves were studied using the PIV technique in a wind tunnel, while the associated turbulence statistics were carefully documented using hot-wire anemometry. We observed the spreading of low-speed fluid by the spanwise travelling streamwise vortices, which seems to have greatly attenuated the turbulence production process. This is very much in line with the finding of DNS studies, where wide low-speed ribbons replaced the low-speed streaks.

  20. A human rights view on access to controlled substances for medical purposes under the international drug control framework.

    PubMed

    Gispen, Marie Elske C

    2013-11-01

    The world is confronted with a major public health deficit caused by poor access to controlled essential medicines under the international drug control framework. This is affecting millions of patients on a daily basis and resulting in numerous human rights violations. The present review contextualises this deficit from a human rights perspective. Drug control efforts are informed by a twofold objective stemming from the double nature of scheduled substances: free access for medical purposes should be ensured, though non-medical use of substances such as opium should be restricted. The international drug control framework is, in theory, based on this twofold notion, however at the level of interpretation, monitoring, and implementation, a one-sided emphasis is demonstrated. By tracing a parallel between the obligations of states under the international drug control framework and those that derive from human rights law, the review shows that the two systems seem incoherent and conflicting in nature and flags the importance of cross-disciplinary research into drug control and human rights.

  1. A realistic model of a wall-transpiration actuator for boundary layer control

    NASA Astrophysics Data System (ADS)

    Tilton, Nils; Cortelezzi, Luca

    2008-11-01

    Experimental studies of boundary layer control using continuously distributed wall-suction usually implement suction by applying a pressure gradient to a layer of porous material via an underlying plenum chamber. Theoretical studies, however, usually neglect the penetration of fluid into the porous layer and plenum chamber by forcing the base flow and velocity perturbations to vanish at the interface with the porous layer. We present a realistic model of a wall-transpiration actuator which implements suction through a fluid saturated, rigid, homogeneous, isotropic, porous layer stretched over a semi-infinite plenum chamber. We test our model on the asymptotic suction boundary layer (ASBL) and perform a linear stability analysis. We take account of the full coupling between the flow fields in the boundary layer, porous layer, and plenum chamber using boundary conditions derived by Ochoa-Tapia and Whitaker (Int. J. Heat Mass Transfer, Vol. 38, 1995, pp 2635-2646). We illustrate the impact of wall-permeability, porous layer thickness, and the plenum chamber on the critical Reynolds number and the stability of the Tollmien-Schlichting wave. We use our model to find the optimal operating conditions of an ASBL which minimize the skin friction drag and power required to apply the suction.

  2. The influence of patriarchal behavior on birth control access and use among recent Hispanic immigrants.

    PubMed

    Gonzalez, Eleazar U; Sable, Marjorie R; Campbell, James D; Dannerbeck, Anne

    2010-08-01

    It is commonly assumed that Hispanic immigrants in the United States subscribe to a patriarchal ideology that keeps women subordinated to men, often through violence and exploitative reproductive behaviors. If this assumption is true, we might expect to find that in the Hispanic culture patriarchal males control decision-making about access to and use of birth control. Structured interviews of 100 Hispanic men and 100 Hispanic women who were recent immigrants to a Midwest community were conducted to examine this assumption. Results did not support this assumption among this study population. We found no patriarchal ideology supporting women's subordination to men, violence as a mechanism of control, reproduction as a way of exploitation, or cultural influences discouraging access to and use of birth control in the Hispanic community. Rather, these immigrants revealed adequate knowledge of birth control use and positive perceptions of gender equality. Gaining a better understanding of the limited influence of patriarchal ideology on the use of birth control and family planning services among this Hispanic community may inform the development of family planning services tailored for new Hispanic immigrants.

  3. MPEG-21 as an access control tool for the National Health Service Care Records Service.

    PubMed

    Brox, Georg A

    2005-01-01

    Since the launch of the National Health Service (NHS) Care Records Service with plans to share patient information across England, there has been an emphasis on the need for manageable access control methods. MPEG-21 is a structured file format which includes an Intellectual Property Management and Protection (IPMP) function using XML to present all digitally stored items in the patient record. Using DICreator software, patient records consisting of written text, audio-recordings, non-X-ray digital imaging and video sequences were linked up successfully. Audio records were created using Talk-Back 2002 to standardize and optimize recording quality. The recorded reports were then linked and archived using iTunes. A key was used each time the file was displayed to secure access to confidential patient data. The building of the correct file structure could be monitored during the entire creation of the file. The results demonstrated the ability to ensure secure access of the MPEG-21 file by both health-care professionals and patients by use of different keys and a specific MPEG-21 browser. The study also showed that the enabling of IPMP will provide accurate audit trails to authenticate appropriate access to medical information. PMID:16035983

  4. Ferroelectric control of magnetic domains in ultra-thin cobalt layers

    SciTech Connect

    Huang, Z.; Stolichnov, I.; Setter, N.; Bernand-Mantel, A.; Borrel, J.; Pizzini, S.; Ranno, L.; Herrera Diez, L.; Auffret, S.; Gaudin, G.; Boulle, O.

    2013-11-25

    Non-volatile ferroelectric control of magnetic domains has been demonstrated in ultra-thin cobalt layers at room temperature. The sensitivity of magnetic anisotropy energy to the electronic structure in a few atomic layers adjacent to the interface allows for ferroelectric control of coercivity and magnetic domain dynamics. These effects have been monitored and quantified using magneto-optical Kerr effect. In particular, the regimes, where the ferroelectric domains enhance/inhibit the magnetic domain nucleation or increase/reduce domain wall velocity, have been explored. Thus, non-destructive and reversible ferroelectric domain writing provides a tool to define the magnetic domain paths, create nucleation sites, or control domain movement.

  5. Toward an Open-Access Global Database for Mapping, Control, and Surveillance of Neglected Tropical Diseases

    PubMed Central

    Hürlimann, Eveline; Schur, Nadine; Boutsika, Konstantina; Stensgaard, Anna-Sofie; Laserna de Himpsl, Maiti; Ziegelbauer, Kathrin; Laizer, Nassor; Camenzind, Lukas; Di Pasquale, Aurelio; Ekpo, Uwem F.; Simoonga, Christopher; Mushinge, Gabriel; Saarnak, Christopher F. L.; Utzinger, Jürg; Kristensen, Thomas K.; Vounatsou, Penelope

    2011-01-01

    Background After many years of general neglect, interest has grown and efforts came under way for the mapping, control, surveillance, and eventual elimination of neglected tropical diseases (NTDs). Disease risk estimates are a key feature to target control interventions, and serve as a benchmark for monitoring and evaluation. What is currently missing is a georeferenced global database for NTDs providing open-access to the available survey data that is constantly updated and can be utilized by researchers and disease control managers to support other relevant stakeholders. We describe the steps taken toward the development of such a database that can be employed for spatial disease risk modeling and control of NTDs. Methodology With an emphasis on schistosomiasis in Africa, we systematically searched the literature (peer-reviewed journals and ‘grey literature’), contacted Ministries of Health and research institutions in schistosomiasis-endemic countries for location-specific prevalence data and survey details (e.g., study population, year of survey and diagnostic techniques). The data were extracted, georeferenced, and stored in a MySQL database with a web interface allowing free database access and data management. Principal Findings At the beginning of 2011, our database contained more than 12,000 georeferenced schistosomiasis survey locations from 35 African countries available under http://www.gntd.org. Currently, the database is expanded to a global repository, including a host of other NTDs, e.g. soil-transmitted helminthiasis and leishmaniasis. Conclusions An open-access, spatially explicit NTD database offers unique opportunities for disease risk modeling, targeting control interventions, disease monitoring, and surveillance. Moreover, it allows for detailed geostatistical analyses of disease distribution in space and time. With an initial focus on schistosomiasis in Africa, we demonstrate the proof-of-concept that the establishment and running of a

  6. Control of supersonic wind-tunnel noise by laminarization of nozzle-wall boundary layer

    NASA Technical Reports Server (NTRS)

    Beckwith, I. E.; Harvey, W. D.; Harris, J. E.; Holley, B. B.

    1973-01-01

    One of the principal design requirements for a quiet supersonic or hypersonic wind tunnel is to maintain laminar boundary layers on the nozzle walls and thereby reduce disturbance levels in the test flow. The conditions and apparent reasons for laminar boundary layers which have been observed during previous investigations on the walls of several nozzles for exit Mach numbers from 2 to 20 are reviewed. Based on these results, an analysis and an assessment of nozzle design requirements for laminar boundary layers including low Reynolds numbers, high acceleration, suction slots, wall temperature control, wall roughness, and area suction are presented.

  7. Precise Control of the Number of Layers of Graphene by Picosecond Laser Thinning.

    PubMed

    Lin, Zhe; Ye, Xiaohui; Han, Jinpeng; Chen, Qiao; Fan, Peixun; Zhang, Hongjun; Xie, Dan; Zhu, Hongwei; Zhong, Minlin

    2015-06-26

    The properties of graphene can vary as a function of the number of layers (NOL). Controlling the NOL in large area graphene is still challenging. In this work, we demonstrate a picosecond (ps) laser thinning removal of graphene layers from multi-layered graphene to obtain desired NOL when appropriate pulse threshold energy is adopted. The thinning process is conducted in atmosphere without any coating and it is applicable for graphene films on arbitrary substrates. This method provides many advantages such as one-step process, non-contact operation, substrate and environment-friendly, and patternable, which will enable its potential applications in the manufacturing of graphene-based electronic devices.

  8. The equipment access software for a distributed UNIX-based accelerator control system

    NASA Astrophysics Data System (ADS)

    Trofimov, Nikolai; Zelepoukine, Serguei; Zharkov, Eugeny; Charrue, Pierre; Gareyte, Claire; Poirier, Hervé

    1994-12-01

    This paper presents a generic equipment access software package for a distributed control system using computers with UNIX or UNIX-like operating systems. The package consists of three main components, an application Equipment Access Library, Message Handler and Equipment Data Base. An application task, which may run in any computer in the network, sends requests to access equipment through Equipment Library calls. The basic request is in the form Equipment-Action-Data and is routed via a remote procedure call to the computer to which the given equipment is connected. In this computer the request is received by the Message Handler. According to the type of the equipment connection, the Message Handler either passes the request to the specific process software in the same computer or forwards it to a lower level network of equipment controllers using MIL1553B, GPIB, RS232 or BITBUS communication. The answer is then returned to the calling application. Descriptive information required for request routing and processing is stored in the real-time Equipment Data Base. The package has been written to be portable and is currently available on DEC Ultrix, LynxOS, HPUX, XENIX, OS-9 and Apollo domain.

  9. Frequency-selective design of wireless power transfer systems for controlled access applications

    NASA Astrophysics Data System (ADS)

    Maschino, Tyler Stephen

    Wireless power transfer (WPT) has become a common way to charge or power many types of devices, ranging from cell phones to electric toothbrushes. WPT became popular through the introduction of a transmission mode known as strongly coupled magnetic resonance (SCMR). This means of transmission is non-radiative and enables mid-range WPT. Shortly after the development of WPT via SCMR, a group of researchers introduced the concept of resonant repeaters, which allows power to hop from the source to the device. These repeaters are in resonance with the WPT system, which enables them to propagate the power wirelessly with minimal losses to the environment. Resonant repeaters have rekindled the dream of ubiquitous wireless power. Inherent risks come with the realization of such a dream. One of the most prominent risks, which we set out in this thesis to address, is that of accessibility to the WPT system. We propose the incorporation of a controlled access schema within a WPT system to prevent unwarranted use of wireless power. Our thesis discusses the history of electromagnetism, examines the inception of WPT via SCMR, evaluates recent developments in WPT, and further elaborates on the controlled access schema we wish to contribute to the field.

  10. Electromagnetic interference-aware transmission scheduling and power control for dynamic wireless access in hospital environments.

    PubMed

    Phunchongharn, Phond; Hossain, Ekram; Camorlinga, Sergio

    2011-11-01

    We study the multiple access problem for e-Health applications (referred to as secondary users) coexisting with medical devices (referred to as primary or protected users) in a hospital environment. In particular, we focus on transmission scheduling and power control of secondary users in multiple spatial reuse time-division multiple access (STDMA) networks. The objective is to maximize the spectrum utilization of secondary users and minimize their power consumption subject to the electromagnetic interference (EMI) constraints for active and passive medical devices and minimum throughput guarantee for secondary users. The multiple access problem is formulated as a dual objective optimization problem which is shown to be NP-complete. We propose a joint scheduling and power control algorithm based on a greedy approach to solve the problem with much lower computational complexity. To this end, an enhanced greedy algorithm is proposed to improve the performance of the greedy algorithm by finding the optimal sequence of secondary users for scheduling. Using extensive simulations, the tradeoff in performance in terms of spectrum utilization, energy consumption, and computational complexity is evaluated for both the algorithms. PMID:21843997

  11. A Network Access Control Framework for 6LoWPAN Networks

    PubMed Central

    Oliveira, Luís M. L.; Rodrigues, Joel J. P. C.; de Sousa, Amaro F.; Lloret, Jaime

    2013-01-01

    Low power over wireless personal area networks (LoWPAN), in particular wireless sensor networks, represent an emerging technology with high potential to be employed in critical situations like security surveillance, battlefields, smart-grids, and in e-health applications. The support of security services in LoWPAN is considered a challenge. First, this type of networks is usually deployed in unattended environments, making them vulnerable to security attacks. Second, the constraints inherent to LoWPAN, such as scarce resources and limited battery capacity, impose a careful planning on how and where the security services should be deployed. Besides protecting the network from some well-known threats, it is important that security mechanisms be able to withstand attacks that have not been identified before. One way of reaching this goal is to control, at the network access level, which nodes can be attached to the network and to enforce their security compliance. This paper presents a network access security framework that can be used to control the nodes that have access to the network, based on administrative approval, and to enforce security compliance to the authorized nodes. PMID:23334610

  12. Electromagnetic interference-aware transmission scheduling and power control for dynamic wireless access in hospital environments.

    PubMed

    Phunchongharn, Phond; Hossain, Ekram; Camorlinga, Sergio

    2011-11-01

    We study the multiple access problem for e-Health applications (referred to as secondary users) coexisting with medical devices (referred to as primary or protected users) in a hospital environment. In particular, we focus on transmission scheduling and power control of secondary users in multiple spatial reuse time-division multiple access (STDMA) networks. The objective is to maximize the spectrum utilization of secondary users and minimize their power consumption subject to the electromagnetic interference (EMI) constraints for active and passive medical devices and minimum throughput guarantee for secondary users. The multiple access problem is formulated as a dual objective optimization problem which is shown to be NP-complete. We propose a joint scheduling and power control algorithm based on a greedy approach to solve the problem with much lower computational complexity. To this end, an enhanced greedy algorithm is proposed to improve the performance of the greedy algorithm by finding the optimal sequence of secondary users for scheduling. Using extensive simulations, the tradeoff in performance in terms of spectrum utilization, energy consumption, and computational complexity is evaluated for both the algorithms.

  13. An interaction-based access control model (IBAC) for collaborative services

    SciTech Connect

    Altunay, Mine; Byrd, Gregory T.; Brown, Doug E.; Dean, Ralph A.; /North Carolina State U.

    2008-04-01

    A collaboration is a collection of services that work together to achieve a common goal. Although collaborations help when tackling difficult problems, they lead to security issues. First, a collaboration is often performed by services that are drawn from different security domains. Second, a service interacts with multiple peer services during the collaboration. These interactions are not isolated from one another--e.g., data may flow through a sequence of different services. As a result, a service is exposed to multiple peer services in varying degrees, leading to different security threats. We identify the types of interactions that can be present in collaborations, and discuss the security threats due to each type. We propose a model for representing the collaboration context so that a service can be made aware of the existing interactions. We provide an access control model for a service participating in a collaboration. We couple our access control model with a policy model, so that the access requirements from collaborations can be expressed and evaluated.

  14. Communication, Control, and Computer Access for Disabled and Elderly Individuals. ResourceBook 2: Switches and Environmental Controls. Rehab/Education Technology ResourceBook Series.

    ERIC Educational Resources Information Center

    Brandenburg, Sara A., Ed.; Vanderheiden, Gregg C., Ed.

    One of a series of three resource guides concerned with communication, control, and computer access for disabled and elderly individuals, the directory focuses on switches and environmental controls. The book's three chapters each cover products with the same primary function. Cross reference indexes allow access to listings of products by…

  15. Control and optimization of sealing layer in films

    NASA Astrophysics Data System (ADS)

    Najarzadeh, Zahra

    Heat sealing is the process to achieve the hermetic closure of a package by applying heat and pressure on two polymer films for a specified dwell time. The heat sealing process has been used in packaging of a wide spectrum of products, in particular for food packaging. During the past two decades, heat sealing machinery has been developed for very high speed line production which requires very precise process condition and material optimization. Heat seal process conditions, including temperature, dwell time, and pressure as well as film characteristics such as molecular weight, molecular weight distribution, long and short chain branching are the key factors that control the final quality of the joint. In the first part of this study, we have investigated the interrelated influence of heat seal process parameters on the strengthening of the interface as well as the micro mechanisms involved. The effects of heat seal temperature, pressure, and dwell time on seal strength of LLDPE were illustrated in "time-temperature" and "pressure-temperature" 3D maps, a methodology that is easily applicable to other systems. The interfacial adhesion of semicrystalline polymers was not well understood. We thus studied the adhesion behaviour of LLDPE as a semicrystalline polymer. The results indicated that the time and temperature dependence of seal strength is a consequence of the fraction of amorphous phase available at the interface of films. The seal strength had a linear correlation with the square root of sealing time which was also supported by the welding models. The slope of this linear correlation increased with temperature. This work was followed concurrently by two main approaches: analysis of polymer chain behaviour from microscopic point of view based on reptation theory and conventional macroscopic analysis based on bulk properties of the polymer. Failure mechanisms and fractured surfaces were also analyzed after peeling. Moreover, the topography and morphology of

  16. Optimal Control of Shock Wave Turbulent Boundary Layer Interactions Using Micro-Array Actuation

    NASA Technical Reports Server (NTRS)

    Anderson, Bernhard H.; Tinapple, Jon; Surber, Lewis

    2006-01-01

    The intent of this study on micro-array flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to determine optimal designs of micro-array actuation for controlling the shock wave turbulent boundary layer interactions within supersonic inlets and compare these concepts to conventional bleed performance. The term micro-array refers to micro-actuator arrays which have heights of 25 to 40 percent of the undisturbed supersonic boundary layer thickness. This study covers optimal control of shock wave turbulent boundary layer interactions using standard micro-vane, tapered micro-vane, and standard micro-ramp arrays at a free stream Mach number of 2.0. The effectiveness of the three micro-array devices was tested using a shock pressure rise induced by the 10 shock generator, which was sufficiently strong as to separate the turbulent supersonic boundary layer. The overall design purpose of the micro-arrays was to alter the properties of the supersonic boundary layer by introducing a cascade of counter-rotating micro-vortices in the near wall region. In this manner, the impact of the shock wave boundary layer (SWBL) interaction on the main flow field was minimized without boundary bleed.

  17. On the turbulence-generated sound and control of compressible mixing layers

    NASA Astrophysics Data System (ADS)

    Kleinman, Randall Ray

    A mixing layer is a common model used to study the noise generation and mixing characteristics of the near-nozzle region of jets. This work presents three separate but related studies that investigate sound generation and active control for noise mitigation and mixing enhancement of such mixing layers. High-fidelity direct numerical simulations of temporal and spatial mixing layers are used for this in two and three dimensions. The first study investigates the role of turbulence scales in generating the radiated far-field sound from temporally-developing, Mach 0.9 mixing layers. To do this, four mixing layers were simulated, starting from the same initial conditions but with Reynolds numbers that varied by a factor of twelve. Above a momentum thickness Reynolds number of 300, all the mixing layers radiate over 85 percent of the acoustic energy of the apparently asymptotically high-Reynolds-number value we are able to compute. Wavenumber spectra of turbulence energy and pressure show the expected Reynolds number dependence: the two highest Reynolds number simulations show evidence of an inertial range and Kolmogorov scaling at the highest wavenumbers. Farfield pressure spectra all decay much more rapidly with wavenumber than the corresponding near-field spectra and show significantly less sensitivity to Reynolds number. Low wavenumbers account for nearly all of the radiated acoustic energy. Implications of these results for jet noise large-eddy simulations are discussed. The second study uses direct numerical simulations of Mach 1.3 mixing layers to characterize the physical mechanisms of flow actuation by localized arc-filament plasma actuators. A validated numerical model of the actuator is devised and placed, as in corresponding experiments, in a cavity in the nozzle near its exit. A rapid Joule heating caused by the plasma is thought to be the root mechanism of flow actuation based upon experimental observation. Simulations show that in the confined space of the

  18. Experimental Investigation on Transmission Control Protocol Throughput Behavior in Optical Fiber Access Networks

    NASA Astrophysics Data System (ADS)

    Tego, Edion; Matera, Francesco; del Buono, Donato

    2016-03-01

    This article describes an experimental investigation on the behavior of transmission control protocol in throughput measurements to be used in the verification of the service-level agreement between the Internet service provider and user in terms of line capacity for ultra-broadband access networks typical of fiber-to-the-x architectures. It is experimentally shown different conditions in high bandwidth-delay product links where the estimation of the line capacity based on a single transmission control protocol session results are unreliable. Simple equations reported in this work, and experimentally verified, point out the conditions in terms of packet loss, time delay, and line capacity, that allow consideration of the reliability of the measurement carried out with a single transmission control protocol session test by adopting a suitable measurement time duration.

  19. Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

    DOEpatents

    Fritz, Gregory M; Knepper, Robert Allen; Weihs, Timothy P; Gash, Alexander E; Sze, John S

    2013-04-30

    An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

  20. Layered reactive particles with controlled geometries, energies, and reactivities, and methods for making the same

    DOEpatents

    Fritz, Gregory M.; Weihs, Timothy P.; Grzyb, Justin A.

    2016-07-05

    An energetic composite having a plurality of reactive particles each having a reactive multilayer construction formed by successively depositing reactive layers on a rod-shaped substrate having a longitudinal axis, dividing the reactive-layer-deposited rod-shaped substrate into a plurality of substantially uniform longitudinal segments, and removing the rod-shaped substrate from the longitudinal segments, so that the reactive particles have a controlled, substantially uniform, cylindrically curved or otherwise rod-contoured geometry which facilitates handling and improves its packing fraction, while the reactant multilayer construction controls the stability, reactivity and energy density of the energetic composite.

  1. Development of plasma streamwise vortex generators for increased boundary layer control authority

    NASA Astrophysics Data System (ADS)

    Bowles, Patrick; Schatzman, David; Corke, Thomas; Thomas, Flint

    2009-11-01

    This experimental study focuses on active boundary layer flow control utilizing streamwise vorticity produced by a single dielectric barrier discharge plasma actuator. A novel plasma streamwise vortex generator (PSVG) layout is presented that mimics the passive flow control characteristics of the trapezoidal vane vortex generator. The PSVG consists of a common insulated electrode and multiple, exposed streamwise oriented electrodes used to produce counter-rotating vortical structures. Smoke and oil surface visualization of boundary layer flow over a flat plate compare the characteristics of passive control techniques and different PSVG designs. Passive and active control over a generic wall-mounted hump model, Rec = 288,000-575,000, are compared through static wall pressure measurements along the model's centerline. Different geometric effects of the PSVG electrode configuration were investigated. PSVG's with triangular exposed electrodes outperformed ordinary PSVG's under certain circumstances. The electrode arrangement produced flow control mechanisms and effectiveness similar to the passive trapezoidal vane vortex generators.

  2. Wireless Access Control with Smart Antenna for M2M Communications

    NASA Astrophysics Data System (ADS)

    Sakamoto, Hiroshi; Bandai, Masaki; Watanabe, Takashi

    Machine to machine (M2M) is a promising technology to achieve an ubiquitous environment by uniting machines and machines over the Internet. The network used for M2M consists of core network and access network. This paper discusses effective controls of the wireless access network for M2M. Among typical examples of the wireless access network for M2M is a wireless sensor network (WSN). WSN for M2M may require energy efficiency, high reliability and throughput. For these requirements, in this paper, we propose a scheme to build a hierarchical sensor network using smart antenna. The proposed scheme uses omni-directional antennas together with smart antennas. Since smart antennas can extend communications distance, the proposed scheme enables reduction of number of hops to reduce the traffic load on relay nodes. As a result, the energy consumption, data collection ratio and throughput can be improved. We implement the proposed scheme on a real testbed. The testbed uses UNAGI as smart antenna nodes and Mica Mote as sensor nodes. In addition to the fundamental evaluation on the testbed, we simulate large-scale sensor networks. The results show the effectiveness of the proposed hierarchical sensor network with smart antennas.

  3. Controllable growth of layered selenide and telluride heterostructures and superlattices using molecular beam epitaxy

    DOE PAGES

    Vishwanath, Suresh; Liu, Xinyu; Rouvimov, Sergei; Basile, Leonardo; Lu, Ning; Azcatl, Angelica; Magno, Katrina; Wallace, Robert M.; Kim, Moon; Idrobo, Juan -Carlos; et al

    2016-01-06

    Layered materials are an actively pursued area of research for realizing highly scaled technologies involving both traditional device structures as well as new physics. Lately, non-equilibrium growth of 2D materials using molecular beam epitaxy (MBE) is gathering traction in the scientific community and here we aim to highlight one of its strengths, growth of abrupt heterostructures, and superlattices (SLs). In this work we present several of the firsts: first growth of MoTe2 by MBE, MoSe2 on Bi2Se3 SLs, transition metal dichalcogenide (TMD) SLs, and lateral junction between a quintuple atomic layer of Bi2Te3 and a triple atomic layer of MoTe2.more » In conclusion, reflected high electron energy diffraction oscillations presented during the growth of TMD SLs strengthen our claim that ultrathin heterostructures with monolayer layer control is within reach.« less

  4. Transmission of terahertz waves through layered superconductors controlled by a dc magnetic field

    NASA Astrophysics Data System (ADS)

    Apostolov, S. S.; Maizelis, Z. A.; Makarov, N. M.; Pérez-Rodríguez, F.; Rokhmanova, T. N.; Yampol'skii, V. A.

    2016-07-01

    The transmission of THz electromagnetic waves via a slab of layered superconductor in the presence of dc magnetic field H0 is theoretically studied. We demonstrate that the external dc field turns the layered superconductor into nonuniform medium with spatially and frequency-dependent dielectric permittivity. Even a relatively weak dc magnetic field, when the superconductor is in the Meissner state, significantly affects the transmittance of the layered superconductor. Moreover, the proper choice of H0 can provide the perfect transparency of the slab. In addition, the dc magnetic field changes the dependence of the transmittance on the slab thickness, the frequency, and the incident angle of the wave. Thus, it can serve as an effective tool to control the transmissivity of layered superconductors.

  5. Ligand Layer Engineering To Control Stability and Interfacial Properties of Nanoparticles.

    PubMed

    Schulz, Florian; Dahl, Gregor T; Besztejan, Stephanie; Schroer, Martin A; Lehmkühler, Felix; Grübel, Gerhard; Vossmeyer, Tobias; Lange, Holger

    2016-08-01

    The use of mixed ligand layers including poly(ethylene glycol)-based ligands for the functionalization of nanoparticles is a very popular strategy in the context of nanomedicine. However, it is challenging to control the composition of the ligand layer and maintain high colloidal and chemical stability of the conjugates. A high level of control and stability are crucial for reproducibility, upscaling, and safe application. In this study, gold nanoparticles with well-defined mixed ligand layers of α-methoxypoly(ethylene glycol)-ω-(11-mercaptoundecanoate) (PEGMUA) and 11-mercaptoundecanoic acid (MUA) were synthesized and characterized by ATR-FTIR spectroscopy and gel electrophoresis. The colloidal and chemical stability of the conjugates was tested by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and UV/vis spectroscopy based experiments, and their interactions with cells were analyzed by elemental analysis. We demonstrate that the alkylene spacer in PEGMUA is the key feature for the controlled synthesis of mixed layer conjugates with very high colloidal and chemical stability and that a controlled synthesis is not possible using regular PEG ligands without the alkylene spacer. With the results of our stability tests, the molecular structure of the ligands can be clearly linked to the colloidal and chemical stabilization. We expect that the underlying design principle can be generalized to improve the level of control in nanoparticle surface chemistry. PMID:27458652

  6. Adaptive nonlinear polynomial neural networks for control of boundary layer/structural interaction

    NASA Technical Reports Server (NTRS)

    Parker, B. Eugene, Jr.; Cellucci, Richard L.; Abbott, Dean W.; Barron, Roger L.; Jordan, Paul R., III; Poor, H. Vincent

    1993-01-01

    The acoustic pressures developed in a boundary layer can interact with an aircraft panel to induce significant vibration in the panel. Such vibration is undesirable due to the aerodynamic drag and structure-borne cabin noises that result. The overall objective of this work is to develop effective and practical feedback control strategies for actively reducing this flow-induced structural vibration. This report describes the results of initial evaluations using polynomial, neural network-based, feedback control to reduce flow induced vibration in aircraft panels due to turbulent boundary layer/structural interaction. Computer simulations are used to develop and analyze feedback control strategies to reduce vibration in a beam as a first step. The key differences between this work and that going on elsewhere are as follows: that turbulent and transitional boundary layers represent broadband excitation and thus present a more complex stochastic control scenario than that of narrow band (e.g., laminar boundary layer) excitation; and secondly, that the proposed controller structures are adaptive nonlinear infinite impulse response (IIR) polynomial neural network, as opposed to the traditional adaptive linear finite impulse response (FIR) filters used in most studies to date. The controllers implemented in this study achieved vibration attenuation of 27 to 60 dB depending on the type of boundary layer established by laminar, turbulent, and intermittent laminar-to-turbulent transitional flows. Application of multi-input, multi-output, adaptive, nonlinear feedback control of vibration in aircraft panels based on polynomial neural networks appears to be feasible today. Plans are outlined for Phase 2 of this study, which will include extending the theoretical investigation conducted in Phase 2 and verifying the results in a series of laboratory experiments involving both bum and plate models.

  7. Adaptive nonlinear polynomial neural networks for control of boundary layer/structural interaction

    NASA Astrophysics Data System (ADS)

    Parker, B. Eugene, Jr.; Cellucci, Richard L.; Abbott, Dean W.; Barron, Roger L.; Jordan, Paul R., III; Poor, H. Vincent

    1993-12-01

    The acoustic pressures developed in a boundary layer can interact with an aircraft panel to induce significant vibration in the panel. Such vibration is undesirable due to the aerodynamic drag and structure-borne cabin noises that result. The overall objective of this work is to develop effective and practical feedback control strategies for actively reducing this flow-induced structural vibration. This report describes the results of initial evaluations using polynomial, neural network-based, feedback control to reduce flow induced vibration in aircraft panels due to turbulent boundary layer/structural interaction. Computer simulations are used to develop and analyze feedback control strategies to reduce vibration in a beam as a first step. The key differences between this work and that going on elsewhere are as follows: that turbulent and transitional boundary layers represent broadband excitation and thus present a more complex stochastic control scenario than that of narrow band (e.g., laminar boundary layer) excitation; and secondly, that the proposed controller structures are adaptive nonlinear infinite impulse response (IIR) polynomial neural network, as opposed to the traditional adaptive linear finite impulse response (FIR) filters used in most studies to date. The controllers implemented in this study achieved vibration attenuation of 27 to 60 dB depending on the type of boundary layer established by laminar, turbulent, and intermittent laminar-to-turbulent transitional flows. Application of multi-input, multi-output, adaptive, nonlinear feedback control of vibration in aircraft panels based on polynomial neural networks appears to be feasible today. Plans are outlined for Phase 2 of this study, which will include extending the theoretical investigation conducted in Phase 2 and verifying the results in a series of laboratory experiments involving both bum and plate models.

  8. Complexity control for high-efficiency video coding by coding layers complexity allocations

    NASA Astrophysics Data System (ADS)

    Fang, Jiunn-Tsair; Liang, Kai-Wen; Chen, Zong-Yi; Hsieh, Wei; Chang, Pao-Chi

    2016-03-01

    The latest video compression standard, high-efficiency video coding (HEVC), provides quad-tree structures of coding units (CUs) and four coding tree depths to facilitate coding efficiency. The HEVC encoder considerably increases the computational complexity to levels inappropriate for video applications of power-constrained devices. This work, therefore, proposes a complexity control method for the low-delay P-frame configuration of the HEVC encoder. The complexity control mechanism is among the group of pictures layer, frame layer, and CU layer, and each coding layer provides a distinct method for complexity allocation. Furthermore, the steps in the prediction unit encoding procedure are reordered. By allocating the complexity to each coding layer of HEVC, the proposed method can simultaneously satisfy the entire complexity constraint (ECC) for entire sequence encoding and the instant complexity constraint (ICC) for each frame during real-time encoding. Experimental results showed that as the target complexity under both the ECC and ICC was reduced to 80% and 60%, respectively, the decrease in the average Bjøntegaard delta peak signal-to-noise ratio was ˜0.1 dB with an increase of 1.9% in the Bjøntegaard delta rate, and the complexity control error was ˜4.3% under the ECC and 4.3% under the ICC.

  9. Discrete-Layer Piezoelectric Plate and Shell Models for Active Tip-Clearance Control

    NASA Technical Reports Server (NTRS)

    Heyliger, P. R.; Ramirez, G.; Pei, K. C.

    1994-01-01

    The objectives of this work were to develop computational tools for the analysis of active-sensory composite structures with added or embedded piezoelectric layers. The targeted application for this class of smart composite laminates and the analytical development is the accomplishment of active tip-clearance control in turbomachinery components. Two distinct theories and analytical models were developed and explored under this contract: (1) a discrete-layer plate theory and corresponding computational models, and (2) a three dimensional general discrete-layer element generated in curvilinear coordinates for modeling laminated composite piezoelectric shells. Both models were developed from the complete electromechanical constitutive relations of piezoelectric materials, and incorporate both displacements and potentials as state variables. This report describes the development and results of these models. The discrete-layer theories imply that the displacement field and electrostatic potential through-the-thickness of the laminate are described over an individual layer rather than as a smeared function over the thickness of the entire plate or shell thickness. This is especially crucial for composites with embedded piezoelectric layers, as the actuating and sensing elements within these layers are poorly represented by effective or smeared properties. Linear Lagrange interpolation polynomials were used to describe the through-thickness laminate behavior. Both analytic and finite element approximations were used in the plane or surface of the structure. In this context, theoretical developments are presented for the discrete-layer plate theory, the discrete-layer shell theory, and the formulation of an exact solution for simply-supported piezoelectric plates. Finally, evaluations and results from a number of separate examples are presented for the static and dynamic analysis of the plate geometry. Comparisons between the different approaches are provided when

  10. Face Recognition for Access Control Systems Combining Image-Difference Features Based on a Probabilistic Model

    NASA Astrophysics Data System (ADS)

    Miwa, Shotaro; Kage, Hiroshi; Hirai, Takashi; Sumi, Kazuhiko

    We propose a probabilistic face recognition algorithm for Access Control System(ACS)s. Comparing with existing ACSs using low cost IC-cards, face recognition has advantages in usability and security that it doesn't require people to hold cards over scanners and doesn't accept imposters with authorized cards. Therefore face recognition attracts more interests in security markets than IC-cards. But in security markets where low cost ACSs exist, price competition is important, and there is a limitation on the quality of available cameras and image control. Therefore ACSs using face recognition are required to handle much lower quality images, such as defocused and poor gain-controlled images than high security systems, such as immigration control. To tackle with such image quality problems we developed a face recognition algorithm based on a probabilistic model which combines a variety of image-difference features trained by Real AdaBoost with their prior probability distributions. It enables to evaluate and utilize only reliable features among trained ones during each authentication, and achieve high recognition performance rates. The field evaluation using a pseudo Access Control System installed in our office shows that the proposed system achieves a constant high recognition performance rate independent on face image qualities, that is about four times lower EER (Equal Error Rate) under a variety of image conditions than one without any prior probability distributions. On the other hand using image difference features without any prior probabilities are sensitive to image qualities. We also evaluated PCA, and it has worse, but constant performance rates because of its general optimization on overall data. Comparing with PCA, Real AdaBoost without any prior distribution performs twice better under good image conditions, but degrades to a performance as good as PCA under poor image conditions.

  11. Dynamic Key Management Schemes for Secure Group Access Control Using Hierarchical Clustering in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Tsaur, Woei-Jiunn; Pai, Haw-Tyng

    2008-11-01

    The applications of group computing and communication motivate the requirement to provide group access control in mobile ad hoc networks (MANETs). The operation in MANETs' groups performs a decentralized manner and accommodated membership dynamically. Moreover, due to lack of centralized control, MANETs' groups are inherently insecure and vulnerable to attacks from both within and outside the groups. Such features make access control more challenging in MANETs. Recently, several researchers have proposed group access control mechanisms in MANETs based on a variety of threshold signatures. However, these mechanisms cannot actually satisfy MANETs' dynamic environments. This is because the threshold-based mechanisms cannot be achieved when the number of members is not up to the threshold value. Hence, by combining the efficient elliptic curve cryptosystem, self-certified public key cryptosystem and secure filter technique, we construct dynamic key management schemes based on hierarchical clustering for securing group access control in MANETs. Specifically, the proposed schemes can constantly accomplish secure group access control only by renewing the secure filters of few cluster heads, when a cluster head joins or leaves a cross-cluster. In such a new way, we can find that the proposed group access control scheme can be very effective for securing practical applications in MANETs.

  12. Experimental Investigation of Normal Shock Boundary-Layer Interaction with Hybrid Flow Control

    NASA Technical Reports Server (NTRS)

    Vyas, Manan A.; Hirt, Stefanie M.; Anderson, Bernhard H.

    2012-01-01

    Hybrid flow control, a combination of micro-ramps and micro-jets, was experimentally investigated in the 15x15 cm Supersonic Wind Tunnel (SWT) at the NASA Glenn Research Center. Full factorial, a design of experiments (DOE) method, was used to develop a test matrix with variables such as inter-ramp spacing, ramp height and chord length, and micro-jet injection flow ratio. A total of 17 configurations were tested with various parameters to meet the DOE criteria. In addition to boundary-layer measurements, oil flow visualization was used to qualitatively understand shock induced flow separation characteristics. The flow visualization showed the normal shock location, size of the separation, path of the downstream moving counter-rotating vortices, and corner flow effects. The results show that hybrid flow control demonstrates promise in reducing the size of shock boundary-layer interactions and resulting flow separation by means of energizing the boundary layer.

  13. Immobilization of chlorophyll by using layer-by-layer technique for controlled release systems and photodynamic inactivation.

    PubMed

    Gorza, Filipe D S; da Silva, Romário J; Trescher, Tarquin F; Pedro, Graciela C; de Sousa, Maria A Oliveira; Souto, Paula C S; Silva, Josmary R; de Souza, Nara C

    2016-09-01

    The development of systems for the controlled release of drugs is important because they allow the control of drug absorption and tissue distribution and also can reduce local toxicity. This study aimed to assemble and characterize two types of release systems, consisting of layer-by-layer films obtained from poly(allylamine) hydrochloride with chlorophyll (PAH/CHL films) or chlorophyll incorporated into dipalmitoylphosphatidylcholine liposomes (PAH/Lip+CHL films). For these systems, the molecular aggregation, growth process, thermally stimulated desorption, wettability, and controlling release of CHL was studied by using UV-vis spectroscopy and wetting contact angle analysis. In addition, experiments of photodynamic inactivation using PAH/CHL or PAH/Lip+CHL films with a 633-nm laser light were performed and the susceptibility of Candida albicans (C. albicans) to this approach was examined. Fluorescence and atomic force microscopies were used to investigate the surface morphology after the application of the photoinactivation procedure. A redshift of the UV-vis spectrum associated to films when compared with the spectrum of the CHL solution indicated a molecular aggregation of CHL molecules in the films. The film growth process was determined by a nucleation and a growth of spheroids or rods for either PAH/Lip+CHL or PAH/CHL films, respectively. Thermally activated desorption experiments indicated that interactions between CHL and PAH (126kJ/mol) in PAH/CHL or between Lip+CHL and PAH (140kJ/mol) in PAH/Lip+CHL films may be governed by electrostatic interactions. The wettability of PAH/Lip+CHL films was larger than that for PAH/CHL films, which can be attributed to hydrophilic groups on the surface of the DPPC liposomes. Release experiments revealed that free CHL in PAH/CHL films was released more slowly than its partner incorporated into liposomes. After the photodynamic inactivation, results of survival fraction and fluorescence microscopy revealed that C

  14. Immobilization of chlorophyll by using layer-by-layer technique for controlled release systems and photodynamic inactivation.

    PubMed

    Gorza, Filipe D S; da Silva, Romário J; Trescher, Tarquin F; Pedro, Graciela C; de Sousa, Maria A Oliveira; Souto, Paula C S; Silva, Josmary R; de Souza, Nara C

    2016-09-01

    The development of systems for the controlled release of drugs is important because they allow the control of drug absorption and tissue distribution and also can reduce local toxicity. This study aimed to assemble and characterize two types of release systems, consisting of layer-by-layer films obtained from poly(allylamine) hydrochloride with chlorophyll (PAH/CHL films) or chlorophyll incorporated into dipalmitoylphosphatidylcholine liposomes (PAH/Lip+CHL films). For these systems, the molecular aggregation, growth process, thermally stimulated desorption, wettability, and controlling release of CHL was studied by using UV-vis spectroscopy and wetting contact angle analysis. In addition, experiments of photodynamic inactivation using PAH/CHL or PAH/Lip+CHL films with a 633-nm laser light were performed and the susceptibility of Candida albicans (C. albicans) to this approach was examined. Fluorescence and atomic force microscopies were used to investigate the surface morphology after the application of the photoinactivation procedure. A redshift of the UV-vis spectrum associated to films when compared with the spectrum of the CHL solution indicated a molecular aggregation of CHL molecules in the films. The film growth process was determined by a nucleation and a growth of spheroids or rods for either PAH/Lip+CHL or PAH/CHL films, respectively. Thermally activated desorption experiments indicated that interactions between CHL and PAH (126kJ/mol) in PAH/CHL or between Lip+CHL and PAH (140kJ/mol) in PAH/Lip+CHL films may be governed by electrostatic interactions. The wettability of PAH/Lip+CHL films was larger than that for PAH/CHL films, which can be attributed to hydrophilic groups on the surface of the DPPC liposomes. Release experiments revealed that free CHL in PAH/CHL films was released more slowly than its partner incorporated into liposomes. After the photodynamic inactivation, results of survival fraction and fluorescence microscopy revealed that C

  15. Privacy-aware access control for video data in intelligent surveillance systems

    NASA Astrophysics Data System (ADS)

    Vagts, Hauke; Jakoby, Andreas

    2012-06-01

    Surveillance systems became powerful. Objects can be identified and intelligent surveillance services can generate events when a specific situation occurs. Such surveillance services can be organized in a Service Oriented Architecture (SOA) to fulfill surveillance tasks for specific purposes. Therefore the services process information on a high level, e.g., just the position of an object. Video data is still required to visualize a situation to an operator and is required as evidence in court. Processing of personal related and sensitive information threatens privacy. To protect the user and to be compliant with legal requirements it must be ensured that sensitive information can only be processed for a defined propose by specific users or services. This work proposes an architecture for Access Control that enforces the separation of data between different surveillance tasks. Access controls are enforced at different levels: for the users starting the tasks, for the services within the tasks processing data stored in central store or calculated by other services and for sensor related services that extract information out of the raw data and provide them.

  16. Security analysis and improvements of authentication and access control in the Internet of Things.

    PubMed

    Ndibanje, Bruce; Lee, Hoon-Jae; Lee, Sang-Gon

    2014-08-13

    Internet of Things is a ubiquitous concept where physical objects are connected over the internet and are provided with unique identifiers to enable their self-identification to other devices and the ability to continuously generate data and transmit it over a network. Hence, the security of the network, data and sensor devices is a paramount concern in the IoT network as it grows very fast in terms of exchanged data and interconnected sensor nodes. This paper analyses the authentication and access control method using in the Internet of Things presented by Jing et al. (Authentication and Access Control in the Internet of Things. In Proceedings of the 2012 32nd International Conference on Distributed Computing Systems Workshops, Macau, China, 18-21 June 2012, pp. 588-592). According to our analysis, Jing et al.'s protocol is costly in the message exchange and the security assessment is not strong enough for such a protocol. Therefore, we propose improvements to the protocol to fill the discovered weakness gaps. The protocol enhancements facilitate many services to the users such as user anonymity, mutual authentication, and secure session key establishment. Finally, the performance and security analysis show that the improved protocol possesses many advantages against popular attacks, and achieves better efficiency at low communication cost.

  17. Security Analysis and Improvements of Authentication and Access Control in the Internet of Things

    PubMed Central

    Ndibanje, Bruce; Lee, Hoon-Jae; Lee, Sang-Gon

    2014-01-01

    Internet of Things is a ubiquitous concept where physical objects are connected over the internet and are provided with unique identifiers to enable their self-identification to other devices and the ability to continuously generate data and transmit it over a network. Hence, the security of the network, data and sensor devices is a paramount concern in the IoT network as it grows very fast in terms of exchanged data and interconnected sensor nodes. This paper analyses the authentication and access control method using in the Internet of Things presented by Jing et al (Authentication and Access Control in the Internet of Things. In Proceedings of the 2012 32nd International Conference on Distributed Computing Systems Workshops, Macau, China, 18–21 June 2012, pp. 588–592). According to our analysis, Jing et al.'s protocol is costly in the message exchange and the security assessment is not strong enough for such a protocol. Therefore, we propose improvements to the protocol to fill the discovered weakness gaps. The protocol enhancements facilitate many services to the users such as user anonymity, mutual authentication, and secure session key establishment. Finally, the performance and security analysis show that the improved protocol possesses many advantages against popular attacks, and achieves better efficiency at low communication cost. PMID:25123464

  18. Security analysis and improvements of authentication and access control in the Internet of Things.

    PubMed

    Ndibanje, Bruce; Lee, Hoon-Jae; Lee, Sang-Gon

    2014-01-01

    Internet of Things is a ubiquitous concept where physical objects are connected over the internet and are provided with unique identifiers to enable their self-identification to other devices and the ability to continuously generate data and transmit it over a network. Hence, the security of the network, data and sensor devices is a paramount concern in the IoT network as it grows very fast in terms of exchanged data and interconnected sensor nodes. This paper analyses the authentication and access control method using in the Internet of Things presented by Jing et al. (Authentication and Access Control in the Internet of Things. In Proceedings of the 2012 32nd International Conference on Distributed Computing Systems Workshops, Macau, China, 18-21 June 2012, pp. 588-592). According to our analysis, Jing et al.'s protocol is costly in the message exchange and the security assessment is not strong enough for such a protocol. Therefore, we propose improvements to the protocol to fill the discovered weakness gaps. The protocol enhancements facilitate many services to the users such as user anonymity, mutual authentication, and secure session key establishment. Finally, the performance and security analysis show that the improved protocol possesses many advantages against popular attacks, and achieves better efficiency at low communication cost. PMID:25123464

  19. Improved efficiency access control equipment and explosive, weapons and drug abuse detection

    SciTech Connect

    Jenkins, A.; Milford, A.; Woollven, J.

    1985-01-01

    The second generation portal explosives detector has been designed with increased detection capability and convenience in service. The method of detection and performance relative to the first generation is described. A novel method of auto-calibration and self diagnosis is described and results are discussed. Improvements in convenience of operation have been achieved and operating space and costs reduced by combining metal detection capability, together with explosives detection. This allows both alarm signal and diagnostic outputs to be combined on a single remote panel in the guard room, and reduces the number of guards needed to man the access control. This type of access control is entirely a defensive measure against attack but a further additional feature is proposed which will also check the state of mind of all personnel passing through the check point. Any person suffering from the effect of narcotic or alcohol will be detected by their inability to reproduce their normal signature. A new method of signature analysis in five dimensions is described together with proposals for integrating the check without increasing the time in the test area. Some recent results on the effects of alcohol on signature reproduction is given.

  20. Hybrid Multi-Layer Network Control for Emerging Cyber-Infrastructures

    SciTech Connect

    Summerhill, Richard

    2009-08-14

    There were four basic task areas identified for the Hybrid-MLN project. They are: o Multi-Layer, Multi-Domain, Control Plane Architecture and Implementation, o Heterogeneous DataPlane Testing, o Simulation, o Project Publications, Reports, and Presentations.

  1. Laser Energy Deposition for Shock Wave Boundary Layer Control at Supersonic Speeds

    NASA Astrophysics Data System (ADS)

    Erdem, E.; Kontis, K.; Osuka, T.; Majima, R.; Tamba, T.; Sasoh, Akihiro

    Shock Wave Boundary Layer Interactions (SWBLIs) can induce separation which causes loss of a control surface effectiveness, drop of an air intake efficiency and it may be the origin of large scale fluctuations such as air-intake buzz, buffeting or fluctuating side loads in separated propulsive nozzles

  2. Gate controllable resistive random access memory devices using reduced graphene oxide

    NASA Astrophysics Data System (ADS)

    Hazra, Preetam; Resmi, A. N.; Jinesh, K. B.

    2016-04-01

    The biggest challenge in the resistive random access memory (ReRAM) technology is that the basic operational parameters, such as the set and reset voltages, the current on-off ratios (hence the power), and their operational speeds, strongly depend on the active and electrode materials and their processing methods. Therefore, for its actual technological implementations, the unification of the operational parameters of the ReRAM devices appears to be a difficult task. In this letter, we show that by fabricating a resistive memory device in a thin film transistor configuration and thus applying an external gate bias, we can control the switching voltage very accurately. Taking partially reduced graphene oxide, the gate controllable switching is demonstrated, and the possible mechanisms are discussed.

  3. Analysis of the TDRS multiple access system for possible use as an attitude control system sensor

    NASA Technical Reports Server (NTRS)

    Blevins, Bruce Allyn; Sank, Victor J.

    1993-01-01

    A member of the constellation of TDR satellites (TDRS) has experienced a failure of its prime earth sensor. Failure of the remaining earth sensor could result in the inability of the satellite to control its attitude and provide user services. Loss of the satellite would be a serious event. The multiple access (MA) antenna array on the TDRS has been proposed for use as a backup sensor for the attitude control system. This paper describes our analysis of the performance of the MA array as an interferometer used for accurate attitude determination. A least squares fit of a plane to the MA phase information appears to represent the TDRS body roll and pitch within about 0.1 deg. This is sufficient for SGL pointing and MA and SSA user services. Analytic improvements that include ionospheric correction may yield sufficient accuracy for KSA user services.

  4. Preliminary assessment of Tongue Drive System in medium term usage for computer access and wheelchair control.

    PubMed

    Yousefi, Behnaz; Huo, Xueliang; Ghovanloo, Maysam

    2011-01-01

    Tongue Drive System (TDS) is a wireless, wearable assistive technology that enables individuals with severe motor impairments access computers, drive wheelchairs, and control their environments using tongue motion. In this paper, we have evaluated the TDS performance as a computer input device using ISO9241-9 standard tasks for pointing and selecting, based on the well known Fitts' Law, and as a powered wheelchair controller through an obstacle course navigation task. Nine able-bodied subjects who already had tongue piercing participated in this trial over 5 sessions during 5 weeks, allowing us to study the TDS learning process and its current limiting factors. Subjects worn tongue rings made of titanium in the form of a barbell with a small rare earth magnetic tracer hermetically sealed inside the upper ball. Comparing the results between 1(st) and 5(th) sessions showed that subjects' performance improved in all the measures through 5 sessions, demonstrating the effects of learning. PMID:22255650

  5. 17 CFR 240.15c3-5 - Risk management controls for brokers or dealers with market access.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Risk management controls for... Markets § 240.15c3-5 Risk management controls for brokers or dealers with market access. (a) For the... establish, document, and maintain a system of risk management controls and supervisory procedures...

  6. 17 CFR 240.15c3-5 - Risk management controls for brokers or dealers with market access.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Risk management controls for... Markets § 240.15c3-5 Risk management controls for brokers or dealers with market access. (a) For the... establish, document, and maintain a system of risk management controls and supervisory procedures...

  7. 17 CFR 240.15c3-5 - Risk management controls for brokers or dealers with market access.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Risk management controls for... Markets § 240.15c3-5 Risk management controls for brokers or dealers with market access. (a) For the... establish, document, and maintain a system of risk management controls and supervisory procedures...

  8. 17 CFR 240.15c3-5 - Risk management controls for brokers or dealers with market access.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Risk management controls for... Markets § 240.15c3-5 Risk management controls for brokers or dealers with market access. (a) For the... establish, document, and maintain a system of risk management controls and supervisory procedures...

  9. Regularized inversion of controlled source audio-frequency magnetotelluric data in horizontally layered transversely isotropic media

    NASA Astrophysics Data System (ADS)

    Zhou, Jianmei; Wang, Jianxun; Shang, Qinglong; Wang, Hongnian; Yin, Changchun

    2014-04-01

    We present an algorithm for inverting controlled source audio-frequency magnetotelluric (CSAMT) data in horizontally layered transversely isotropic (TI) media. The popular inversion method parameterizes the media into a large number of layers which have fixed thickness and only reconstruct the conductivities (e.g. Occam's inversion), which does not enable the recovery of the sharp interfaces between layers. In this paper, we simultaneously reconstruct all the model parameters, including both the horizontal and vertical conductivities and layer depths. Applying the perturbation principle and the dyadic Green's function in TI media, we derive the analytic expression of Fréchet derivatives of CSAMT responses with respect to all the model parameters in the form of Sommerfeld integrals. A regularized iterative inversion method is established to simultaneously reconstruct all the model parameters. Numerical results show that the inverse algorithm, including the depths of the layer interfaces, can significantly improve the inverse results. It can not only reconstruct the sharp interfaces between layers, but also can obtain conductivities close to the true value.

  10. Gradient fiber electrospinning of layered scaffolds using controlled transitions in fiber diameter.

    PubMed

    Grey, Casey P; Newton, Scott T; Bowlin, Gary L; Haas, Thomas W; Simpson, David G

    2013-07-01

    We characterize layered, delamination resistant, tissue engineering scaffolds produced by gradient electrospinning using computational fluid dynamics, measurements of fiber diameter with respect to dynamic changes in polymer concentration, SEM analysis, and materials testing. Gradient electrospinning delivers a continuously variable concentration of polymer to the electrospinning jet, resulting in scaffolds that exhibit controlled transitions in fiber diameter across the Z-axis. This makes it possible to produce scaffolds that exhibit very different fiber sizes and material properties on opposing surfaces while eliminating the boundary layers that lead to delamination failures. In materials testing bi-layered laminated electrospun scaffolds (layer 1 = <250 nm, layer 2 = 1000 nm diameter polycaprolactone fibers) exhibit ductile properties and undergo multiphasic failure. In contrast, scaffolds, produced by gradient electrospinning fabricated with fibers of this type on opposing surfaces fracture and fail as unified, and mechanically integrated, structures. Gradient electrospinning also eliminates the anisotropic strain properties observed in scaffolds composed of highly aligned fibers. In burst testing, scaffolds composed of aligned fibers produced using gradient electrospinning exhibit superior material properties with respect to scaffolds composed of random or aligned fibers produced from a single polymer concentration or as bi-layered, laminated structures.

  11. Resistive switching of a TaO{sub x}/TaON double layer via ionic control of carrier tunneling

    SciTech Connect

    Jeon, Heeyoung; Park, Jingyu; Kim, Hyunjung; Jang, Woochool; Song, Hyoseok; Kang, Chunho; Seo, Hyungtak; Jeon, Hyeongtag

    2014-04-14

    Resistance random access memory (RRAM) is an attractive candidate for future non-volatile memory due to its superior features. As the oxide thickness is scaled down, the charge transport mechanism is also subject to the transition from hopping to tunneling dominant process, which is critically related to the interfacial electronic band structure. A TaO{sub x}/TaON double layer-based RRAM is fabricated and characterized in this work. Upon TaON insertion at the lower interface, the improved switching behavior is observed. The TaON at the bottom electrode interface blocks oxygen vacancy percolation due to strong N-O bonds and also modifies interfacial band alignment to lower the injected electron energy from bottom electrode due to higher tunneling barrier height than that of TaO{sub x}/Pt. This study suggested that a defect-minimized insertion layer like TaON with a proper interfacial band alignment is pivotal in RRAM for the effective ionic control of carrier tunneling resulting in non-linear I-V behavior with improved properties.

  12. Effects of Hybrid Flow Control on a Normal Shock Boundary-Layer Interaction

    NASA Technical Reports Server (NTRS)

    Hirt, Stefanie M.; Vyas, Manan A.

    2013-01-01

    Hybrid flow control, a combination of micro-ramps and steady micro-jets, was experimentally investigated in the 15x15 cm Supersonic Wind Tunnel at the NASA Glenn Research Center. A central composite design of experiments method, was used to develop response surfaces for boundary-layer thickness and reversed-flow thickness, with factor variables of inter-ramp spacing, ramp height and chord length, and flow injection ratio. Boundary-layer measurements and wall static pressure data were used to understand flow separation characteristics. A limited number of profiles were measured in the corners of the tunnel to aid in understanding the three-dimensional characteristics of the flowfield.

  13. A highly efficient SDRAM controller supporting variable-length burst access and batch process for discrete reads

    NASA Astrophysics Data System (ADS)

    Li, Nan; Wang, Junzheng

    2016-03-01

    A highly efficient Synchronous Dynamic Random Access Memory (SDRAM) controller supporting variable-length burst access and batch process for discrete reads is proposed in this paper. Based on the Principle of Locality, command First In First Out (FIFO) and address range detector are designed within this controller to accelerate its responses to discrete read requests, which dramatically improves the average Effective Bus Utilization Ratio (EBUR) of SDRAM. Our controller is finally verified by driving the Micron 256-Mb SDRAM MT48LC16M16A2. Successful simulation and verification results show that our controller exhibits much higher EBUR than do most existing designs in case of discrete reads.

  14. Effects of boundary-layer separation controllers on a desktop fume hood.

    PubMed

    Huang, Rong Fung; Chen, Jia-Kun; Hsu, Ching Min; Hung, Shuo-Fu

    2016-10-01

    A desktop fume hood installed with an innovative design of flow boundary-layer separation controllers on the leading edges of the side plates, work surface, and corners was developed and characterized for its flow and containment leakage characteristics. The geometric features of the developed desktop fume hood included a rearward offset suction slot, two side plates, two side-plate boundary-layer separation controllers on the leading edges of the side plates, a slanted surface on the leading edge of the work surface, and two small triangular plates on the upper left and right corners of the hood face. The flow characteristics were examined using the laser-assisted smoke flow visualization technique. The containment leakages were measured by the tracer gas (sulphur hexafluoride) detection method on the hood face plane with a mannequin installed in front of the hood. The results of flow visualization showed that the smoke dispersions induced by the boundary-layer separations on the leading edges of the side plates and work surface, as well as the three-dimensional complex flows on the upper-left and -right corners of the hood face, were effectively alleviated by the boundary-layer separation controllers. The results of the tracer gas detection method with a mannequin standing in front of the hood showed that the leakage levels were negligibly small (≤0.003 ppm) at low face velocities (≥0.19 m/s). PMID:27104797

  15. Control of a shock wave-boundary layer interaction using localized arc filament plasma actuators

    NASA Astrophysics Data System (ADS)

    Webb, Nathan Joseph

    Supersonic flight is currently possible, but expensive. Inexpensive supersonic travel will require increased efficiency of high-speed air entrainment, an integral part of air-breathing propulsion systems. Although mixed compression inlet geometry can significantly improve entrainment efficiency, numerous Shock Wave-Boundary Layer Interactions (SWBLIs) are generated in this configuration. The boundary layer must therefore develop through multiple regions of adverse pressure gradient, causing it to thicken, and, in severe cases, separate. The associated increase in unsteadiness can have adverse effects on downstream engine hardware. The most severe consequence of these interactions is the increased aerodynamic blockage generated by the thickened boundary layer. If the increase is sufficient, it can choke the flow, causing inlet unstart, and resulting in a loss of thrust and high transient forces on the engine, airframe, and aircraft occupants. The potentially severe consequences associated with SWBLIs require flow control to ensure proper operation. Traditionally, boundary layer bleed has been used to control the interaction. Although this method is effective, it has inherent efficiency penalties. Localized Arc Filament Plasma Actuators (LAFPAs) are designed to generate perturbations for flow control. Natural flow instabilities act to amplify certain perturbations, allowing the LAFPAs to control the flow with minimal power input. LAFPAs also have the flexibility to maintain control over a variety of operating conditions. This work seeks to examine the effectiveness of LAFPAs as a separation control method for an oblique, impinging SWBLI. The low frequency unsteadiness in the reflected shock was thought to be the natural manifestation of a Kelvin-Helmholtz instability in the shear layer above the separation region. The LAFPAs were therefore placed upstream of the interaction to allow their perturbations to convect to the receptivity region (near the shear layer origin

  16. Controlled access of p53 to the nucleus regulates its proteasomal degradation by MDM2.

    PubMed

    Davis, James R; Mossalam, Mohanad; Lim, Carol S

    2013-04-01

    The tumor suppressor p53 can be sent to the proteasome for degradation by placing its nucleo-cytoplasmic shuttling under ligand control. Endogenous p53 is ubiquitinated by MDM2 in the nucleus, and controlling the access of p53 to the nuclear compartment regulates its ubiquitination and proteasomal degradation. This was accomplished by the use of a protein switch that places nuclear translocation under the control of externally applied dexamethasone. Fluorescence microscopy revealed that sending protein switch p53 (PS-p53) to the nucleus produces a distinct punctate distribution in both the cytoplasm and nucleus. The nuclear role in accessing the proteasome was investigated by inhibiting classical nuclear export with leptomycin B. Trapping PS-p53 in the nucleus only allows this punctate staining in that compartment, suggesting that PS-p53 must translocate first to the nuclear compartment for cytoplasmic punctate staining to occur. The role of MDM2 binding was explored by inhibiting MDM2/p53 binding with nutlin-3. Inhibition of this interaction blocked both nuclear export and cytoplasmic and nuclear punctate staining, providing evidence that any change in localization after nuclear translocation is due to MDM2 binding. Further, blocking the proteolytic activity of the proteasome maintained the nuclear localization of the construct. Truncations of p53 were made to determine smaller constructs still capable of interacting with MDM2, and their subcellular localization and degradation potential was observed. PS-p53 and a smaller construct containing the two MDM2 binding regions of p53 (Box I + V) were indeed degraded by the proteasome as measured by loss of enhanced green fluorescent protein that was also fused to the construct. The influence of these constructs on p53 gene transactivation function was assessed and revealed that PS-p53 decreased gene transactivation, while PS-p53(Box I + V) did not significantly change baseline gene transactivation.

  17. Controlling Interfacial Reactions and Intermetallic Compound Growth at the Interface of a Lead-free Solder Joint with Layer-by-Layer Transferred Graphene.

    PubMed

    Ko, Yong-Ho; Lee, Jong-Dae; Yoon, Taeshik; Lee, Chang-Woo; Kim, Taek-Soo

    2016-03-01

    The immoderate growth of intermetallic compounds (IMCs) formed at the interface of a solder metal and the substrate during soldering can degrade the mechanical properties and reliability of a solder joint in electronic packaging. Therefore, it is critical to control IMC growth at the solder joints between the solder and the substrate. In this study, we investigated the control of interfacial reactions and IMC growth by the layer-by-layer transfer of graphene during the reflow process at the interface between Sn-3.0Ag-0.5Cu (in wt %) lead-free solder and Cu. As the number of graphene layers transferred onto the surface of the Cu substrate increased, the thickness of the total IMC (Cu6Sn5 and Cu3Sn) layer decreased. After 10 repetitions of the reflow process for 50 s above 217 °C, the melting temperature of Sn-3.0Ag-0.5Cu, with a peak temperature of 250 °C, the increase in thickness of the total IMC layer at the interface with multiple layers of graphene was decreased by more than 20% compared to that at the interface of bare Cu without graphene. Furthermore, the average diameter of the Cu6Sn5 scallops at the interface with multiple layers of graphene was smaller than that at the interface without graphene. Despite 10 repetitions of the reflow process, the growth of Cu3Sn at the interface with multiple layers of graphene was suppressed by more than 20% compared with that at the interface without graphene. The multiple layers of graphene at the interface between the solder metal and the Cu substrate hindered the diffusion of Cu atoms from the Cu substrate and suppressed the reactions between Cu and Sn in the solder. Thus, the multiple layers of graphene transferred at the interface between dissimilar metals can control the interfacial reaction and IMC growth occurring at the joining interface. PMID:26856638

  18. PANATIKI: A Network Access Control Implementation Based on PANA for IoT Devices

    PubMed Central

    Sanchez, Pedro Moreno; Lopez, Rafa Marin; Gomez Skarmeta, Antonio F.

    2013-01-01

    Internet of Things (IoT) networks are the pillar of recent novel scenarios, such as smart cities or e-healthcare applications. Among other challenges, these networks cover the deployment and interaction of small devices with constrained capabilities and Internet protocol (IP)-based networking connectivity. These constrained devices usually require connection to the Internet to exchange information (e.g., management or sensing data) or access network services. However, only authenticated and authorized devices can, in general, establish this connection. The so-called authentication, authorization and accounting (AAA) services are in charge of performing these tasks on the Internet. Thus, it is necessary to deploy protocols that allow constrained devices to verify their credentials against AAA infrastructures. The Protocol for Carrying Authentication for Network Access (PANA) has been standardized by the Internet engineering task force (IETF) to carry the Extensible Authentication Protocol (EAP), which provides flexible authentication upon the presence of AAA. To the best of our knowledge, this paper is the first deep study of the feasibility of EAP/PANA for network access control in constrained devices. We provide light-weight versions and implementations of these protocols to fit them into constrained devices. These versions have been designed to reduce the impact in standard specifications. The goal of this work is two-fold: (1) to demonstrate the feasibility of EAP/PANA in IoT devices; (2) to provide the scientific community with the first light-weight interoperable implementation of EAP/PANA for constrained devices in the Contiki operating system (Contiki OS), called PANATIKI. The paper also shows a testbed, simulations and experimental results obtained from real and simulated constrained devices. PMID:24189332

  19. PANATIKI: a network access control implementation based on PANA for IoT devices.

    PubMed

    Moreno Sanchez, Pedro; Marin Lopez, Rafa; Gomez Skarmeta, Antonio F

    2013-01-01

    Internet of Things (IoT) networks are the pillar of recent novel scenarios, such as smart cities or e-healthcare applications. Among other challenges, these networks cover the deployment and interaction of small devices with constrained capabilities and Internet protocol (IP)-based networking connectivity. These constrained devices usually require connection to the Internet to exchange information (e.g., management or sensing data) or access network services. However, only authenticated and authorized devices can, in general, establish this connection. The so-called authentication, authorization and accounting (AAA) services are in charge of performing these tasks on the Internet. Thus, it is necessary to deploy protocols that allow constrained devices to verify their credentials against AAA infrastructures. The Protocol for Carrying Authentication for Network Access (PANA) has been standardized by the Internet engineering task force (IETF) to carry the Extensible Authentication Protocol (EAP), which provides flexible authentication upon the presence of AAA. To the best of our knowledge, this paper is the first deep study of the feasibility of EAP/PANA for network access control in constrained devices. We provide light-weight versions and implementations of these protocols to fit them into constrained devices. These versions have been designed to reduce the impact in standard specifications. The goal of this work is two-fold: (1) to demonstrate the feasibility of EAP/PANA in IoT devices; (2) to provide the scientific community with the first light-weight interoperable implementation of EAP/PANA for constrained devices in the Contiki operating system (Contiki OS), called PANATIKI. The paper also shows a testbed, simulations and experimental results obtained from real and simulated constrained devices. PMID:24189332

  20. PANATIKI: a network access control implementation based on PANA for IoT devices.

    PubMed

    Moreno Sanchez, Pedro; Marin Lopez, Rafa; Gomez Skarmeta, Antonio F

    2013-11-01

    Internet of Things (IoT) networks are the pillar of recent novel scenarios, such as smart cities or e-healthcare applications. Among other challenges, these networks cover the deployment and interaction of small devices with constrained capabilities and Internet protocol (IP)-based networking connectivity. These constrained devices usually require connection to the Internet to exchange information (e.g., management or sensing data) or access network services. However, only authenticated and authorized devices can, in general, establish this connection. The so-called authentication, authorization and accounting (AAA) services are in charge of performing these tasks on the Internet. Thus, it is necessary to deploy protocols that allow constrained devices to verify their credentials against AAA infrastructures. The Protocol for Carrying Authentication for Network Access (PANA) has been standardized by the Internet engineering task force (IETF) to carry the Extensible Authentication Protocol (EAP), which provides flexible authentication upon the presence of AAA. To the best of our knowledge, this paper is the first deep study of the feasibility of EAP/PANA for network access control in constrained devices. We provide light-weight versions and implementations of these protocols to fit them into constrained devices. These versions have been designed to reduce the impact in standard specifications. The goal of this work is two-fold: (1) to demonstrate the feasibility of EAP/PANA in IoT devices; (2) to provide the scientific community with the first light-weight interoperable implementation of EAP/PANA for constrained devices in the Contiki operating system (Contiki OS), called PANATIKI. The paper also shows a testbed, simulations and experimental results obtained from real and simulated constrained devices.

  1. Turbulent Boundary Layer Separation Control on a Convex Ramp using Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Schatzman, David M.

    2005-11-01

    This work is focused toward the development of active feedback control of turbulent boundary layer separation from a convex ramp surface. The work reported here is performed in a subsonic wind tunnel facility and utilizes single dielectric barrier discharge plasma actuators for separation control. Smoke and oil surface flow visualization are used to characterize the separation in the absence of actuation. The surface mounted plasma actuators are positioned upstream of the flow separation locations. Plasma-induced blowing transfers additional momentum to the boundary layer along the ramp surface and has a beneficial effect on flow reattachment. Experimental results are presented which demonstrate the effects of both steady and unsteady actuation. The effectiveness of the active flow control is documented through surface pressure measurements, LDV measurements, and downstream wake surveys.

  2. Low Mode Control of Cryogenic ICF Fuel Layers Using Infrared Heating

    SciTech Connect

    London, R A; Kozioziemski, B J; Marinak, M M; Kerbel, G D; Bittner, D N

    2005-07-06

    Infrared heating has been demonstrated as an effective technique to smooth solid hydrogen layers inside transparent cryogenic inertial confinement fusion capsules. Control of the first two Legendre modes of the fuel thickness perturbations using two infrared beams injected into a hohlraum was predicted by modeling and experimentally demonstrated. In the current work, we use coupled ray tracing and heat transfer simulations to explore a wider range of control of long scale length asymmetries. We demonstrate several scenarios to control the first four Legendre modes in the fuel layer using four beams. With such a system, it appears possible to smooth both short and long scale length fuel thickness variations in transparent indirect drive inertial confinement fusion targets.

  3. Reactive Control of Boundary Layer Streaks Induced by Freestream Turbulence Using Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Gouder, Kevin; Naguib, Ahmed; Lavoie, Philippe; Morrison, Jonathan

    2015-11-01

    Over the past few years we have carried out a systematic series of investigations aimed at evaluating the capability of a plasma-actuator-based feedforward-feedback control system to weaken streaks induced ``synthetically'' in a Blasius boundary layer via dynamic roughness elements. This work has been motivated by the delay of bypass boundary layer transition in which the streaks form stochastically beneath a freestream with turbulence of intensity of more than approximately 1%. In the present work, we carry forward the knowhow from our previous research in a first attempt to control such naturally occurring streaks. The experimental setup consists of a turbulence-generating grid upstream of a flat plate with a sharp leading edge. At the freestream velocity of the experiment, turbulent spot formation is observed to start at a streamwise location of x ~ 350 mm from the leading edge. The control system is implemented within a streamwise domain stretching from x = 150 mm to 300mm, where the streaks exhibit linear growth. At the upstream and downstream end of the domain a feedforward and a feedback wall-shear-stress sensors are utilized. The output from the sensors is fed to appropriately designed controllers which drive two plasma actuators providing positive and negative wall-normal forcing to oppose naturally occurring high- and low-speed streaks respectively. The results provide an assessment of the viability of the control approach to weaken the boundary layer streaks and to delay transition.

  4. Privacy aware access controls for medical data disclosure on European healthgrids.

    PubMed

    Rahmouni, Hanene Boussi; Solomonides, Tony; Mont, Marco Casassa; Shiu, Simon

    2010-01-01

    To be processed within a healthgrid environment, medical data goes through a complete lifecycle and several stages until it is finally used for the primary reason it has been collected for. This stage is not always the final occurrence of when the data would have been manipulated. The data could rather continue to be needed for secondary purposes of legitimate or non legitimate nature. Although other privacy issues are related to the processing of patient data while it is residing on a healthgrid environment, the control of data disclosure is our primary interest. When sharing medical data between different Healthcare and biomedical research organizations in Europe, it is important that the different parties involved in the sharing handle the data in the same way indicated by the legislation of the member state where the data was originally collected as the requirements might differ from one state to another. Privacy requirements, such as patient consent, may be subject to conflicting conditions between different national frameworks as well as between different legal and ethical frameworks within a single member state. These circumstances have made the compliance management process in European healthgrid very challenging. In this paper we are presenting an approach to tackle these issues by relying on several technologies contained in the semantic web stack. Our work suggests a direct mapping from high level legislation on privacy and data protection to operational level privacy aware controls. Additionally we suggest an architecture for the enforcement of these controls on access control models adopted by healthgrids security infrastructures.

  5. Understanding the Processes Controlling Aerosol-Cloud Interactions in the Arctic Marine Boundary Layer

    NASA Astrophysics Data System (ADS)

    Browse, J.; Carslaw, K. S.; Pringle, K.; Mann, G.; Reddington, C.; Brooks, I. M.; Mulcahy, J.; Young, G.; Allan, J. D.; Liu, D.; Trembath, J.; Dean, A.; Yoshioka, M.

    2015-12-01

    Here we use multiple configurations of the UKCA chemistry and aerosol scheme in a global climate model, capable of simulating cloud condensation nuclei (CCN) and cloud droplet number, to understand the processes controlling aerosol-cloud interactions in the marine Arctic boundary layer. Evaluation against an unprecedented number of aerosol and cloud observations made available through the Global Aerosol Synthesis and Science Project (GASSP), International Arctic Systems for Observing the Atmosphere (IASOA) and the 2013 ACCACIA campaign, suggest that Arctic summertime CCN is well represented in the model. Sensitivity studies indicate that DMS derived nucleation events are the primary source of Arctic summertime aerosol increasing mean (median) surface CCN concentrations north of 70N from 21(14) cm-3 to 46(33) cm-3. However, evaluation against observed aerosol size distributions suggests that UKCA overestimates nucleation mode (~10nm) particle concentrations either due to overestimation of boundary layer nucleation rates or underestimation of the Arctic marine boundary layer condensation sink.

  6. Numerical study of boundary layer separation control using magnetogasdynamic plasma actuators

    SciTech Connect

    Kalra, Chiranjeev S.; Shneider, Mikhail N.; Miles, Richard B.

    2009-10-15

    In this study, an efficient, time dependent, two-dimensional Navier-Stokes numerical code for shockwave boundary layer interaction in air is developed. Nonthermal surface plasma actuation is evaluated for effective shockwave induced boundary layer separation control within supersonic inlets. Specifically, high speed magnetogasdynamic plasma actuators are of interest. In these, localized ionization is produced close to the wall surface and then the flow is accelerated using strong magnetic fields. To replicate the experiments done at large boundary layer thickness, the code is divided into time independent and time dependent regimes to significantly reduce computation time. Computational results are in good agreement with experiments in terms of the flow structure as shown by Schlieren imaging, acetone planar laser scattering, and the static pressure profile on the test section wall.

  7. Precise Control of the Number of Layers of Graphene by Picosecond Laser Thinning

    PubMed Central

    Lin, Zhe; Ye, Xiaohui; Han, Jinpeng; Chen, Qiao; Fan, Peixun; Zhang, Hongjun; Xie, Dan; Zhu, Hongwei; Zhong, Minlin

    2015-01-01

    The properties of graphene can vary as a function of the number of layers (NOL). Controlling the NOL in large area graphene is still challenging. In this work, we demonstrate a picosecond (ps) laser thinning removal of graphene layers from multi-layered graphene to obtain desired NOL when appropriate pulse threshold energy is adopted. The thinning process is conducted in atmosphere without any coating and it is applicable for graphene films on arbitrary substrates. This method provides many advantages such as one-step process, non-contact operation, substrate and environment-friendly, and patternable, which will enable its potential applications in the manufacturing of graphene-based electronic devices. PMID:26111758

  8. Control over the preferred orientation of CIGS films deposited by magnetron sputtering using a wetting layer

    NASA Astrophysics Data System (ADS)

    Yan, Yong; Jiang, Fan; Liu, Lian; Yu, Zhou; Zhang, Yong; Zhao, Yong

    2016-01-01

    A growth method is presented to control the preferred orientation in chalcopyrite CuIn x Ga1- x Se2 (CIGS) thin films grown by magnetron sputtering. Films with (220/204) and (112) preferred orientation as well as randomly oriented films were prepared. The effects of an In2Se3 wetting layer and the working pressure on the texture transition phenomena were examined. A large-grained CIGS film with (220/204) texture was formed at 400°C with the inclusion of a thin (80 nm) In2Se3 layer and liquid phase (excess copper selenide phase) formation, and the reaction mechanism is proposed. The device deposited at 2.0 Pa on an In2Se3 layer exhibited the optimal electrical properties. [Figure not available: see fulltext.

  9. Facile synthesis of CuO nanosheets via the controlled delamination of layered copper hydroxide acetate.

    PubMed

    Demel, Jan; Zhigunov, Alexander; Jirka, Ivan; Klementová, Mariana; Lang, Kamil

    2015-08-15

    CuO nanosheets were prepared by the controlled delamination of layered copper hydroxide acetate followed by the in situ solvothermal transformation of hydroxide to oxide. The reaction was performed in 1-butanol in order to prevent recrystallization or nanoparticle aggregation. Analyses by small angle X-ray scattering, transmission electron microscopy, and atomic force microscopy revealed that the CuO nanosheets are approximately 1 nm thin, corresponding to three to four stacked CuO6 octahedral layers. The average lateral size is approximately 5 nm. The nanosheets form stable dispersions in 1-butanol that are suitable for the fabrication of transparent and homogeneous CuO thin films by spin-coating or inkjet printing techniques. The present synthesis is a rare example of the top down strategy leading to the nanometric two-dimensional nanosheets of non-layered oxide materials. PMID:25942095

  10. i Barrier layer mechanism engineering in calcium copper titanate thin film capacitors through microstructure control

    NASA Astrophysics Data System (ADS)

    Paisley, E. A.; Losego, M. D.; Aygun, S. M.; Craft, H. S.; Maria, J.-P.

    2008-12-01

    A peak permittivity greater than 10 000 has been achieved for calcium copper titanate (CCT) thin films by engineering a thin film microstructure that maximizes space charge contributions to polarizability. This permittivity is an order of magnitude greater than previous polycrystalline thin film efforts. This unique microstructure control is accomplished using a chemical solution deposition process flow that produces highly dense parallel layers ˜100 nm in thickness. We observe a thickness dependent permittivity where the entire film thickness constitutes the conducting region of a barrier layer capacitor despite the presence of multiple grain boundaries within that thickness. The model predictions are in good agreement with experimental data and are consistent with existing literature reports. These trends in permittivity with dielectric thickness raise new questions regarding the nature of barrier layers in CCT—and specifically, these results suggest that grain boundaries may not always participate as high resistance interlayers.

  11. Towards precise defect control in layered oxide structures by using oxide molecular beam epitaxy

    PubMed Central

    Baiutti, Federico; Christiani, Georg

    2014-01-01

    Summary In this paper we present the atomic-layer-by-layer oxide molecular beam epitaxy (ALL-oxide MBE) which has been recently installed in the Max-Planck Institute for Solid State Research and we report on its present status, providing some examples that demonstrate its successful application in the synthesis of different layered oxides, with particular reference to superconducting La2CuO4 and insulator-to-metal La2− xSrxNiO4. We briefly review the ALL-oxide MBE technique and its unique capabilities in the deposition of atomically smooth single-crystal thin films of various complex oxides, artificial compounds and heterostructures, introducing our goal of pursuing a deep investigation of such systems with particular emphasis on structural defects, with the aim of tailoring their functional properties by precise defects control. PMID:24995148

  12. e-VLBI Access Point (eAXP) - a centralized control and EGAE configuration / management application

    NASA Astrophysics Data System (ADS)

    Ruszczyk, Chester Whitney, Alan

    Setting up experiments to utilize Experiment Guided Adaptive Endpoint (EGAE) and e-VLBI is presently a complex and time intensive process requiring scientific, Mark5 and networking knowledge. There is no central access to point to configure and manage all of these aspects of an experiment. The e-VLBI Access Point (eAXP) is a centralized control plane management tool that offers a GUI interface to augment the command line interface presently being used to set up and conduct experiments. eAXP contains three major toolsets: one to set up and execute an experiment using real-time or non-real time modes; the second to configure and manage EGAE; and a third to view statistics of the experiments. Initially the overall system architecture for eAXP is presented, followed by details of the Experiment Profiler toolset including screen shots of the system presently being tested. This will be followed by how eAXP will support real-time modes interfacing to the Dynamic Resource Allocation over GMPLS Optical Network (DRAGON) resource management project.

  13. Quantitative trait loci controlling light and hormone response in two accessions of Arabidopsis thaliana.

    PubMed Central

    Borevitz, Justin O; Maloof, Julin N; Lutes, Jason; Dabi, Tsegaye; Redfern, Joanna L; Trainer, Gabriel T; Werner, Jonathan D; Asami, Tadao; Berry, Charles C; Weigel, Detlef; Chory, Joanne

    2002-01-01

    We have mapped quantitative trait loci (QTL) responsible for natural variation in light and hormone response between the Cape Verde Islands (Cvi) and Landsberg erecta (Ler) accessions of Arabidopsis thaliana using recombinant inbred lines (RILs). Hypocotyl length was measured in four light environments: white, blue, red, and far-red light and in the dark. In addition, white light plus gibberellin (GA) and dark plus the brassinosteroid biosynthesis inhibitor brassinazole (BRZ) were used to detect hormone effects. Twelve QTL were identified that map to loci not previously known to affect light response, as well as loci where candidate genes have been identified from known mutations. Some QTL act in all environments while others show genotype-by-environment interaction. A global threshold was established to identify a significant epistatic interaction between two loci that have few main effects of their own. LIGHT1, a major QTL, has been confirmed in a near isogenic line (NIL) and maps to a new locus with effects in all light environments. The erecta mutation can explain the effect of the HYP2 QTL in the blue, BRZ, and dark environments, but not in far-red. LIGHT2, also confirmed in an NIL, has effects in white and red light and shows interaction with GA. The phenotype and map position of LIGHT2 suggest the photoreceptor PHYB as a candidate gene. Natural variation in light and hormone response thus defines both new genes and known genes that control light response in wild accessions. PMID:11861571

  14. Point and counterpoint: patient control of access to data in their electronic health records.

    PubMed

    Caine, Kelly; Tierney, William M

    2015-01-01

    Information collection, storage, and management is central to the practice of health care. For centuries, patients' and providers' expectations kept medical records confidential between providers and patients. With the advent of electronic health records, patient health information has become more widely available to providers and health care managers and has broadened its potential use beyond individual patient care. Adhering to the principles of Fair Information Practice, including giving patients control over the availability and use of their individual health records, would improve care by fostering the sharing of sensitive information between patients and providers. However, adherence to such principles could put patients at risk for unsafe care as a result of both missed opportunities for providing needed care as well as provision of contraindicated care, as it would prevent health care providers from having full access to health information. Patients' expectations for the highest possible quality and safety of care, therefore, may be at odds with their desire to limit provider access to their health records. Conversely, provider expectations that patients would willingly seek care for embarrassing conditions and disclose sensitive information may be at odds with patients' information privacy rights. An open dialogue between patients and providers will be necessary to balance respect for patient rights with provider need for patient information.

  15. Point and counterpoint: patient control of access to data in their electronic health records.

    PubMed

    Caine, Kelly; Tierney, William M

    2015-01-01

    Information collection, storage, and management is central to the practice of health care. For centuries, patients' and providers' expectations kept medical records confidential between providers and patients. With the advent of electronic health records, patient health information has become more widely available to providers and health care managers and has broadened its potential use beyond individual patient care. Adhering to the principles of Fair Information Practice, including giving patients control over the availability and use of their individual health records, would improve care by fostering the sharing of sensitive information between patients and providers. However, adherence to such principles could put patients at risk for unsafe care as a result of both missed opportunities for providing needed care as well as provision of contraindicated care, as it would prevent health care providers from having full access to health information. Patients' expectations for the highest possible quality and safety of care, therefore, may be at odds with their desire to limit provider access to their health records. Conversely, provider expectations that patients would willingly seek care for embarrassing conditions and disclose sensitive information may be at odds with patients' information privacy rights. An open dialogue between patients and providers will be necessary to balance respect for patient rights with provider need for patient information. PMID:25480723

  16. Iterative algorithm analysis for phase-only diffractive control access system

    NASA Astrophysics Data System (ADS)

    Mihailescu, Mona; Preda, Alexandru; Cojoc, Dan; Scarlat, Eugen; Preda, Liliana

    2007-08-01

    A new architecture with two phases-only diffractive elements and one decryption mask for optical control access system is presented. Only three different persons which keep this element have the permission to access together. The Iterative Fourier Transform Algorithm (IFTA) is analyzed for phase-only diffractive optical elements (PODE) design with different constraints in the input and output plane and the optimal variant is chosen for better image quality in the output plane (big value for diffraction efficiency and small value for merit function and signal to noise ratio). For higher security we propose different incident waves. That are compared with the case when the first phase-only diffractive element and decryption masks are designed together in an extended iteration and the output images of them (first desired image) is taken over the second phase-only diffractive element. In order to increase security level, this finally PODE are designed to increase some parts from the first desired image. Only with this condition the key image on the detector is formed.

  17. Experimental investigation of the flow over three d-type microgeometries for boundary layer control

    NASA Astrophysics Data System (ADS)

    Hildalgo Ardana, Pablo

    2008-04-01

    An experimental investigation of the flow over three microgeometries was conducted in order to study its boundary layer control capabilities. Drag reduction and boundary layer control are two of the most researched areas in fluid mechanics. The necessity of reducing drag over vehicles is imperative to reduce the power needed to move a vehicle, or to save millions of gallons of fuel; this can also contribute to a reduction of the emissions of pollutant gases to the atmosphere. It has been estimated that a reduction in drag of 1% on an airplane can save the airlines around 200,000 in fuel costs per airliner per year, and worldwide this could result in total savings in fuel of approximately 1 billion every year. This experimental research was inspired by fast swimming shark species and the denticles present on their skin. Among other purposes, these denticles have some hydrodynamic capabilities that are investigated in this experimental work. Replicas of the denticles of the Shortfin Mako shark (Isurus oxyrinchus), which is speculated to be the fastest swimming shark, have been fabricated and they were embedded on a flat plate. Two additional simplified models of the shark skin consisting of embedded cavities, a two-dimensional grooved surface and a squared sawtooth geometry, were also tested. Time-resolved digital particle image velocimetry (TR-DPIV) measurements were taken in order to characterize the cavity vortices formed inside the geometries, as well as velocity profile measurements to identify the stability of the boundary layer over the geometries. The cavity vortices introduce a partial slip condition into the flow which affects the stability of the boundary layer. The results indicate that the shark skin can work as a boundary layer control mechanism by delaying or inhibiting separation over the shark's body, thereby reducing pressure drag. The ribs on the front side of the shark skin denticles promoted secondary vorticity that was measured under both

  18. Force control of a tri-layer conducting polymer actuator using optimized fuzzy logic control

    NASA Astrophysics Data System (ADS)

    Itik, Mehmet; Sabetghadam, Mohammadreza; Alici, Gursel

    2014-12-01

    Conducting polymers actuators (CPAs) are potential candidates for replacing conventional actuators in various fields, such as robotics and biomedical engineering, due to their advantageous properties, which includes their low cost, light weight, low actuation voltage and biocompatibility. As these actuators are very suitable for use in micro-nano manipulation and in injection devices in which the magnitude of the force applied to the target is of crucial importance, the force generated by CPAs needs to be accurately controlled. In this paper, a fuzzy logic (FL) controller with a Mamdani inference system is designed to control the blocking force of a trilayer CPA with polypyrrole electrodes, which operates in air. The particle swarm optimization (PSO) method is employed to optimize the controller’s membership function parameters and therefore enhance the performance of the FL controller. An adaptive neuro-fuzzy inference system model, which can capture the nonlinear dynamics of the actuator, is utilized in the optimization process. The optimized Mamdani FL controller is then implemented on the CPA experimentally, and its performance is compared with a non-optimized fuzzy controller as well as with those obtained from a conventional PID controller. The results presented indicate that the blocking force at the tip of the CPA can be effectively controlled by the optimized FL controller, which shows excellent transient and steady state characteristics but increases the control voltage compared to the non-optimized fuzzy controllers.

  19. Access Denied

    ERIC Educational Resources Information Center

    Villano, Matt

    2008-01-01

    Building access control (BAC)--a catchall phrase to describe the systems that control access to facilities across campus--has traditionally been handled with remarkably low-tech solutions: (1) manual locks; (2) electronic locks; and (3) ID cards with magnetic strips. Recent improvements have included smart cards and keyless solutions that make use…

  20. Feedback linearisation control of an induction machine augmented by single-hidden layer neural networks

    NASA Astrophysics Data System (ADS)

    Ait Abbas, Hamou; Belkheiri, Mohammed; Zegnini, Boubakeur

    2016-01-01

    We consider adaptive output feedback control methodology of highly uncertain nonlinear systems with both parametric uncertainties and unmodelled dynamics. The approach is also applicable to systems of unknown, but bounded dimension. However, the relative degree of the regulated output is assumed to be known. This new control strategy is proposed to address the tracking problem of an induction motor based on a modified field-oriented control method. The obtained controller is then augmented by an online neural network that serves as an approximator for the neglected dynamics and modelling errors. The network weight adaptation rule is derived from the Lyapunov stability analysis, that guarantees boundedness of all the error signals of the closed-loop system. Computer simulations of an output feedback controlled induction machine, augmented via single-hidden-layer neural networks, demonstrate the practical potential of the proposed control algorithm.

  1. A method to implement fine-grained access control for personal health records through standard relational database queries.

    PubMed

    Sujansky, Walter V; Faus, Sam A; Stone, Ethan; Brennan, Patricia Flatley

    2010-10-01

    Online personal health records (PHRs) enable patients to access, manage, and share certain of their own health information electronically. This capability creates the need for precise access-controls mechanisms that restrict the sharing of data to that intended by the patient. The authors describe the design and implementation of an access-control mechanism for PHR repositories that is modeled on the eXtensible Access Control Markup Language (XACML) standard, but intended to reduce the cognitive and computational complexity of XACML. The authors implemented the mechanism entirely in a relational database system using ANSI-standard SQL statements. Based on a set of access-control rules encoded as relational table rows, the mechanism determines via a single SQL query whether a user who accesses patient data from a specific application is authorized to perform a requested operation on a specified data object. Testing of this query on a moderately large database has demonstrated execution times consistently below 100ms. The authors include the details of the implementation, including algorithms, examples, and a test database as Supplementary materials.

  2. Laminar and turbulent boundary layer separation control of Mako shark skin

    NASA Astrophysics Data System (ADS)

    Afroz, Farhana

    The Shortfin Mako shark (Isurus oxyrinchus) is one of the fastest swimmers in nature. They have an incredible turning agility and are estimated to achieve speeds as high as ten body lengths per second. Shark skin is known to contain flexible denticles or scales, capable of being actuated by the flow whereby a unique boundary layer control (BLC) method could reduce drag. It is hypothesized that shark scales bristle when the flow is reversed, and this bristling may serve to control flow separation by (1) inhibiting the localized flow reversal near the wall and (2) inducing mixing within the boundary layer by cavities formed between the scales that increases the momentum of the flow near the wall. To test this hypothesis, samples of Mako shark skin have been studied under various amounts of adverse pressure gradient (APG). These samples were collected from the flank region of a Shortfin Mako shark where the scales have the greatest potential for separation control due to the highest bristling angles. An easy technique for inducing boundary layer separation has been developed where an APG can be generated and varied using a rotating cylinder. Both the experimental and numerical studies showed that the amount of APG can be varied as a function of cylinder rotation speed or cylinder gap height for a wide range of Reynolds numbers. This method of generating an APG is used effectively for inducing both laminar and turbulent boundary layer separation over a flat plate. Laminar and turbulent boundary layer separation studies conducted over a smooth plate have been compared with the same setup repeated over shark skin. The time-averaged DPIV results showed that shark scale bristling controlled both laminar and turbulent boundary layer separation to a measurable extent. It shows that the shark scales cause an early transition to turbulence and reduce the degree of laminar separation. For turbulent separation, reverse flow near the wall and inside the boundary layer is

  3. New scheme of variable optical buffer for IP packets used in access control of HORNET

    NASA Astrophysics Data System (ADS)

    Fang, Nian; Wang, Lutang; Huang, Zhaoming

    2002-09-01

    A new scheme of variable optical buffer for IP packets is reported. It may be used in access control of HORNET (Hybrid Optoelectronic Ring NETwork), to avoid collision of added packet and the packet already on the ring and improve the loss ratio of the packets. In this scheme, a new multi-wavelength fiber loop memory technique is employed. This architecture uses the wavelength converter (WC) to specify the packets delay and wavelength conversion is accomplished by the technique of four-wave-mixing (FWM) with a semiconductor optical amplifier (SOA). The range of delay is 10 to 9990 bytes periods. First, architecture, operation principle, characteristics and applications of this scheme of variable optical buffer are introduced. Next, a new unslotted CSMA/CA MAC scheme based on the variable optical buffer is briefly introduced too. Finally, the simulation results are presented.

  4. A Cloud-Assisted Random Linear Network Coding Medium Access Control Protocol for Healthcare Applications

    PubMed Central

    Kartsakli, Elli; Antonopoulos, Angelos; Alonso, Luis; Verikoukis, Christos

    2014-01-01

    Relay sensor networks are often employed in end-to-end healthcare applications to facilitate the information flow between patient worn sensors and the medical data center. Medium access control (MAC) protocols, based on random linear network coding (RLNC), are a novel and suitable approach to efficiently handle data dissemination. However, several challenges arise, such as additional delays introduced by the intermediate relay nodes and decoding failures, due to channel errors. In this paper, we tackle these issues by adopting a cloud architecture where the set of relays is connected to a coordinating entity, called cloud manager. We propose a cloud-assisted RLNC-based MAC protocol (CLNC-MAC) and develop a mathematical model for the calculation of the key performance metrics, namely the system throughput, the mean completion time for data delivery and the energy efficiency. We show the importance of central coordination in fully exploiting the gain of RLNC under error-prone channels. PMID:24618727

  5. [Assessment of exposure to cancerogenic aromatic hydrocarbon during controlled-access highways management activities].

    PubMed

    Martinotti, I; Cirla, A M; Cottica, D; Cirla, P E

    2011-01-01

    The purpose of this study was an integrated assessment of exposure to benzene and Polycyclic Aromatic Hydrocarbons (PAH) in 29 workers employed to manage a controlled-access highways. A campaign was performed in summertime by environmental monitoring (active and passive airborne personal sampler), as well as by biological monitoring (urine samples of the beginning and of the end of daily shift, baseline after two days of vacation). The measured environmental levels did not differ from background environmental concentrations found in a metropolitan area (i.e. benzo[a]pyrene < 1 ng/m3; benzene < 5 mcg/m3), and the results of biological monitoring were in agreement and were compatible with extra-professional habits of the investigated subjects (1-hydroxipyrene 50-990 ng/g creatinine; unmetabolized benzene 15-2010 ng/I; t-t muconic acid < 4-222 mcg/g creatinine).

  6. A Time Tree Medium Access Control for Energy Efficiency and Collision Avoidance in Wireless Sensor Networks

    PubMed Central

    Lee, Kilhung

    2010-01-01

    This paper presents a medium access control and scheduling scheme for wireless sensor networks. It uses time trees for sending data from the sensor node to the base station. For an energy efficient operation of the sensor networks in a distributed manner, time trees are built in order to reduce the collision probability and to minimize the total energy required to send data to the base station. A time tree is a data gathering tree where the base station is the root and each sensor node is either a relaying or a leaf node of the tree. Each tree operates in a different time schedule with possibly different activation rates. Through the simulation, the proposed scheme that uses time trees shows better characteristics toward burst traffic than the previous energy and data arrival rate scheme. PMID:22319270

  7. An Extended Role-Based Access Control Model for Delegating Obligations

    NASA Astrophysics Data System (ADS)

    Ben-Ghorbel-Talbi, Meriam; Cuppens, Frédéric; Cuppens-Boulahia, Nora; Bouhoula, Adel

    The main aim of access control models is to provide means to simplify the management of the security policy, which is a fastidious and error-prone task. Supporting delegation is considered as an important mean to decentralize the administration and therefore to allow security policy to be more flexible and easier to manipulate. Our main contribution is the proposition of a unified model to the administration and delegation of obligations. Managing such delegations implies more requirements than managing traditional privileges delegation. In fact, delegating obligations may include two interpretations: the delegation of the obligation and the delegation of the responsibility related to this obligation. Therefore, it is important to deal with these two notions separately. Moreover, since delegating an obligation involves the delegation of sanctions, then the consent of the user who receives this delegation may be required in some cases. We address in this paper these requirements and we propose a formalism to deal with them.

  8. Large-Eddy Simulation of Shock-Wave Boundary Layer Interaction and its Control Using Sparkjet

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Yao, Yufeng; Fang, Jian; Gan, Tian; Lu, Lipeng

    2016-06-01

    Large-eddy simulation (LES) of an oblique shock-wave generated by an 8° sharp wedge impinging onto a spatially-developing Mach 2.3 turbulent boundary layer and their interactions has been carried out in this study. The Reynolds number based on the incoming flow property and the boundary layer displacement thickness at the impinging point without shock-wave is 20,000. The detailed numerical approaches are described and the inflow turbulence is generated using the digital filter method to avoid artificial temporal or streamwise periodicity. Numerical results are compared with the available wind tunnel PIV measurements of the same flow conditions. Further LES study on the control of flow separation due to the strong shock-viscous interaction is also conducted by using an active control actuator “SparkJet” concept. The single-pulsed characteristics of the control device are obtained and compared with the experiments. Instantaneous flowfield shows that the “SparkJet” promotes the flow mixing in the boundary layer and enhances its ability to resist the flow separation. The time and spanwise averaged skin friction coefficient distribution demonstrates that the separation bubble length is reduced by maximum 35% with the control exerted.

  9. Layer-controlled stylolite growth and the creation and destruction of local seals

    NASA Astrophysics Data System (ADS)

    Koehn, Daniel; Pataki Rood, Daisy; Beaudoin, Nicolas; Aleksans, Janis; Bons, Paul; Gomez-Rivas, Enrique

    2015-04-01

    Cores of carbonate Zechstein sediments in the Lean Gas Field in northern Germany show a dense set of sedimentary stylolites. We studied these structures in detail using scans of cores, thin-sections, roughness analysis, SEM-EDS studies and a set of numerical simulations in order to understand timing and depth of stylolite growth, the development of varying stylolite patterns and their influence on fluid flow. The studied cores have a depth of about 4000m and it is expected that they experienced a minor inversion in the Cretaceous so that their original depth may have been up to 4500m. We studied the roughness of the stylolites and used a stress inversion technique to determine the depth at which they grew. The determined depth of growth is in the order of 4150m with an error of plus-minus 300m. This value represents the latest stylolite activity and indicates that they have been active until late in the burial history. SEM and EDS analysis on stylolite thin sections shows that the stylolites separate strongly dedolomitized sections from sections that still contain a large amount of dolomite. In addition stylolite seams capture or shield dolomitized parts of the rock. Dissolution holes are also partly linked to stylolite teeth indicating that fluid flow is significantly influenced by the presence of stylolites. Stylolite shapes and thus potentially their sealing capacity vary significantly throughout the cores from flat stylolites to small wavy ones all the way to stylolites showing extreme spikes and teeth. Quite often dark layers seem to control stylolite shapes. In order to understand the influence of layers on stylolite growth we use a numerical model that can treat the dynamics of the process linking elasticity with a dissolution routine. In this model we find that layers that dissolve slower can pin stylolite teeth and thus develop extremely long and spiky geometries. Growth typically happens in two to three stages depending on whether or not the pinning layer

  10. Controlling electronic access to the spin excitations of a single molecule in a tunnel junction

    NASA Astrophysics Data System (ADS)

    Hirjibehedin, Cyrus F.; Warner, Ben; El Hallak, Fadi; Prueser, Henning; Ajibade, Afolabi; Gill, Tobias G.; Fisher, Andrew J.; Persson, Mats

    Spintronic phenomena can be utilized to create new devices with applications in data storage and sensing. Scaling these down to the single molecule level requires controlling the properties of the current-carrying orbitals to enable access to spin states through phenomena such as inelastic electron tunneling. Here we show that the spintronic properties of a tunnel junction containing a single molecule can be controlled by their coupling to the local environment. For tunneling through iron phthalocyanine (FePc) on an insulating copper nitride (Cu2N) monolayer above Cu(001), we find that spin transitions may be strongly excited depending on the binding site of the central Fe atom. Different interactions between the Fe and the underlying Cu or N atoms shift the Fe d-orbitals with respect to the Fermi energy, and control the relative strength of the spin excitations, an effect that can described in a simple co-tunneling model. This work demonstrates the importance of the atomic-scale environment in the development of single molecule spintronic devices.

  11. Thermal Control System Development to Support the Crew Exploration Vehicle and Lunar Surface Access Module

    NASA Technical Reports Server (NTRS)

    Anderson, Molly; Westheimer, David

    2006-01-01

    All space vehicles or habitats require thermal management to maintain a safe and operational environment for both crew and hardware. Active Thermal Control Systems (ATCS) perform the functions of acquiring heat from both crew and hardware within a vehicle, transporting that heat throughout the vehicle, and finally rejecting that energy into space. Almost all of the energy used in a space vehicle eventually turns into heat, which must be rejected in order to maintain an energy balance and temperature control of the vehicle. For crewed vehicles, Active Thermal Control Systems are pumped fluid loops that are made up of components designed to perform these functions. NASA has recently evaluated all of the agency s technology development work and identified key areas that must be addressed to aid in the successful development of a Crew Exploration Vehicle (CEV) and a Lunar Surface Access Module (LSAM). The technologies that have been selected and are currently under development include: fluids that enable single loop ATCS architectures, a gravity insensitive vapor compression cycle heat pump, a sublimator with reduced sensitivity to feedwater contamination, an evaporative heat sink that can operate in multiple ambient pressure environments, a compact spray evaporator, and lightweight radiators that take advantage of carbon composites and advanced optical coatings.

  12. Liquid crystal pretilt angle control using adjustable wetting properties of alignment layers

    SciTech Connect

    Ahn, Han Jin; Kim, Jong Bok; Kim, Kyung Chan; Hwang, Byoung Har; Kim, Jong Tae; Baik, Hong Koo; Park, Jin Seol; Kang, Daeseung

    2007-06-18

    The authors demonstrate the production of amorphous fluorinated carbon (a-C:F) thin film with adjustable wetting properties, inducing variable liquid crystal (LC) pretilt angles. To control the surface wetting properties, they apply a dual radio frequency magnetron system with a controlled power ratio of targets. In this manner we obtain various compositional surfaces with fluorine and carbon components and adjust the surface energy with regard to the various compositions. Whereas the fluorine-rich a-C:F layer shows a preference for homeotropic (vertical) LC alignment, the carbon-rich a-C:F layer shows a planar LC alignment. To achieve uniform LC alignment with a proper pretilt angle, an accelerated Ar{sup +} ion beam irradiates the films after the deposition process. The ion beam selectively destroys the surface bonding of the a-C:F films, yielding an intermediate pretilt angle.

  13. Liquid crystal pretilt angle control using adjustable wetting properties of alignment layers

    NASA Astrophysics Data System (ADS)

    Ahn, Han Jin; Kim, Jong Bok; Kim, Kyung Chan; Hwang, Byoung Har; Kim, Jong Tae; Baik, Hong Koo; Park, Jin Seol; Kang, Daeseung

    2007-06-01

    The authors demonstrate the production of amorphous fluorinated carbon (a-C:F) thin film with adjustable wetting properties, inducing variable liquid crystal (LC) pretilt angles. To control the surface wetting properties, they apply a dual radio frequency magnetron system with a controlled power ratio of targets. In this manner we obtain various compositional surfaces with fluorine and carbon components and adjust the surface energy with regard to the various compositions. Whereas the fluorine-rich a-C :F layer shows a preference for homeotropic (vertical) LC alignment, the carbon-rich a-C :F layer shows a planar LC alignment. To achieve uniform LC alignment with a proper pretilt angle, an accelerated Ar+ ion beam irradiates the films after the deposition process. The ion beam selectively destroys the surface bonding of the a-C :F films, yielding an intermediate pretilt angle.

  14. Towards improving efficiency of control for blowing into a boundary layer through a permeable wall

    NASA Astrophysics Data System (ADS)

    Fomin, V. M.; Kornilov, V. I.; Boiko, A. V.

    2016-08-01

    The results of experimental and numerical investigations of the efficiency of control by an incompressible turbulent boundary layer with the help air blowing through a permeable wall fabricated with maintenance of most of the necessary requirements for the quality and configuration of microapertures and having a low effective roughness are analyzed. Various cases of modeling the process of air blowing into the boundary layer through a specified hi-tech finely perforated surface are considered, and the data for average parameters and characteristics of turbulence of the flow types under investigation are presented. A substantial decrease in the skin-friction coefficient along the model length, which can achieve 90% with increasing the blowing coefficient, is shown. The estimate of the energy consumption for the process of blowing under terrestrial conditions testifies to the high potential of this method of control capable to provide 4-5% gain in the total aerodynamic drag of a simple modeling configuration.

  15. Application of the controlled boundary layer concept for the wall interference reduction

    NASA Astrophysics Data System (ADS)

    Ivanov, A. I.; Kursakov, I. A.; Streltsov, E. V.

    2016-10-01

    Traditional boundaries of transonic wind tunnels (perforated and slotted walls) have some disadvantages that do not allow to completely remove wall interference on all main aerodynamic characteristics. This article focuses on the results of implementation of new boundary condition based, in general, on the idea of jet boundaries. Authors examine the implementation of the controlled boundary layer on solid walls, which characteristics were artificially increased with the aim of near-wall spoiler grid mounted at the test section entrance. The analysis underlines significant decreasing of wall interference on all main aerodynamic characteristics, including lift coefficient and pitching moment coefficient. We conclude that realization of the controlled boundary layer might become simple and rather effective method of wall-interference reduction.

  16. Influence of the alignment layer and the liquid crystal layer thickness on the characteristics of electrically controlled optical modulators

    NASA Astrophysics Data System (ADS)

    Vasil'Ev, V. N.; Konshina, E. A.; Kostomarov, D. S.; Fedorov, M. A.; Amosova, L. P.; Gavrish, E. O.

    2009-06-01

    The screening effect of the amorphous hydrogenated carbon (a-C:H) alignment layer and its dependence on the thickness of a dual-frequency nematic liquid crystal (NLC) layer have been studied. Optimization of the a-C:H layer thickness allows a threshold voltage for the optical S-effect to be reduced and the characteristic switching time and relaxation time of 0.5 and 2.5 ms, respectively, to be obtained for a phase retardation of 2π at a wavelength of 0.86 μm.

  17. Development and characterization of 96 microsatellite markers suitable for QTL mapping and accession control in an Arabidopsis core collection

    PubMed Central

    2014-01-01

    Background To identify plant genes involved in various key traits, QTL mapping is a powerful approach. This approach is based on the use of mapped molecular markers to identify genomic regions controlling quantitative traits followed by a fine mapping and eventually positional cloning of candidate genes. Mapping technologies using SNP markers are still rather expensive and not feasible in every laboratory. In contrast, microsatellite (also called SSR for Simple Sequence Repeat) markers are technologically less demanding and less costly for any laboratory interested in genetic mapping. Results In this study, we present the development and the characterization of a panel of 96 highly polymorphic SSR markers along the Arabidopsis thaliana genome allowing QTL mapping among accessions of the Versailles 24 core collection that covers a high percentage of the A. thaliana genetic diversity. These markers can be used for any QTL mapping analysis involving any of these accessions. We optimized the use of these markers in order to reveal polymorphism using standard PCR conditions and agarose gel electrophoresis. In addition, we showed that the use of only three of these markers allows differentiating all 24 accessions which makes this set of markers a powerful tool to control accession identity or any cross between any of these accessions. Conclusion The set of SSR markers developed in this study provides a simple and efficient tool for any laboratory focusing on QTL mapping in A. thaliana and a simple means to control seed stock or crosses between accessions. PMID:24447639

  18. Graphene coated with controllable N-doped carbon layer by molecular layer deposition as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Chen, Yao; Gao, Zhe; Zhang, Bin; Zhao, Shichao; Qin, Yong

    2016-05-01

    In this work, graphene is coated with nitrogen-doped carbon layer, which is produced by a carbonization process of aromatic polyimide (PI) films deposited on the surfaces of graphene by molecular layer deposition (MLD). The utilization of MLD not only allows uniform coating of PI layers on the surfaces of pristine graphene without any surface treatment, but also enables homogenous dispersion of doped nitrogen atoms in the carbonized products. The as-prepared N-doped carbon layer coated graphene (NC-G) exhibited remarkable capacitance performance as electrode materials for supercapacitor, showing a high specific capacitance of 290.2 F g-1 at current density of 1 A g-1 in 6 M KOH aqueous electrolyte, meanwhile maintaining good rate performance and stable cycle capability. The NC-G synthesized by this way represents an alternative promising candidate as electrode material for supercapacitors.

  19. Hot-Film and Hot-Wire Anemometry for a Boundary Layer Active Flow Control Test

    NASA Technical Reports Server (NTRS)

    Lenahan, Keven C.; Schatzman, David M.; Wilson, Jacob Samuel

    2013-01-01

    Unsteady active flow control (AFC) has been used experimentally for many years to minimize bluff-body drag. This technology could significantly improve performance of rotorcraft by cleaning up flow separation. It is important, then, that new actuator technologies be studied for application to future vehicles. A boundary layer wind tunnel was constructed with a 1ft-x-3ft test section and unsteady measurement instrumentation to study how AFC manipulates the boundary layer to overcome adverse pressure gradients and flow separation. This unsteady flow control research requires unsteady measurement methods. In order to measure the boundary layer characteristics, both hot-wire and hot-film Constant Temperature Anemometry is used. A hot-wire probe is mounted in the flow to measure velocity while a hot-film array lays on the test surface to measure skin friction. Hot-film sensors are connected to an anemometer, a Wheatstone bridge circuit with an output that corresponds to the dynamic flow response. From this output, the time varying flow field, turbulence, and flow reversal can be characterized. Tuning the anemometers requires a fan test on the hot-film sensors to adjust each output. This is a delicate process as several variables drastically affect the data, including control resistance, signal input, trim, and gain settings.

  20. Template-Free 3D Microprinting of Metals Using a Force-Controlled Nanopipette for Layer-by-Layer Electrodeposition.

    PubMed

    Hirt, Luca; Ihle, Stephan; Pan, Zhijian; Dorwling-Carter, Livie; Reiser, Alain; Wheeler, Jeffrey M; Spolenak, Ralph; Vörös, János; Zambelli, Tomaso

    2016-03-23

    A novel 3D printing method for voxel-by-voxel metal printing is presented. Hollow atomic force microscopy (AFM) cantilevers are used to locally supply metal ions in an electrochemical cell, enabling a localized electroplating reaction. By exploiting the deflection feedback of these probes, electrochemical 3D metal printing is, for the first time, demonstrated in a layer-by-layer fashion, enabling the fabrication of arbitrary-shaped geometries.

  1. Template-Free 3D Microprinting of Metals Using a Force-Controlled Nanopipette for Layer-by-Layer Electrodeposition.

    PubMed

    Hirt, Luca; Ihle, Stephan; Pan, Zhijian; Dorwling-Carter, Livie; Reiser, Alain; Wheeler, Jeffrey M; Spolenak, Ralph; Vörös, János; Zambelli, Tomaso

    2016-03-23

    A novel 3D printing method for voxel-by-voxel metal printing is presented. Hollow atomic force microscopy (AFM) cantilevers are used to locally supply metal ions in an electrochemical cell, enabling a localized electroplating reaction. By exploiting the deflection feedback of these probes, electrochemical 3D metal printing is, for the first time, demonstrated in a layer-by-layer fashion, enabling the fabrication of arbitrary-shaped geometries. PMID:26783090

  2. Sheet shape-controlling method for hundreds-of-nanometer-thick polymer film using soluble polymer layer

    NASA Astrophysics Data System (ADS)

    Shimbo, Sota; Fujie, Toshinori; Iwase, Eiji

    2016-06-01

    We proposed a sheet shape-controlling method for a hundreds-of-nanometers-thick polymeric ultrathin film (referred to as a “nanosheet”) for folding the film into a cylindrical shape and unfolding the film into a flat shape. To control the shape of the nanosheet, we used a triple-layered structure, which included a nanosheet and additional two layers of a water-soluble polymer. The additional two layers are thicker than the nanosheet, and one of the two layers was loaded to prestretch that layer. Therefore, the triple-layered structure was folded into a cylindrical shape owing to strain mismatch between the two layers and unfolded into a flat shape after the dissolution of the two layers. In this study, we could successfully estimate the radius of curvature of the triple-layered structure by considering the strain mismatch between the two layers. In addition, we confirmed that the triple-layered structure unfolded into a flat shape by the dissolution of the two layers.

  3. Controlling multidrug-resistant tuberculosis and access to expensive drugs: a rational framework.

    PubMed Central

    Pablos-Mendez, Ariel; Gowda, Deepthiman K.; Frieden, Thomas R.

    2002-01-01

    The emergence and spread of multidrug-resistant tuberculosis (MDR-TB), i.e. involving resistance to at least isoniazid and rifampicin, could threaten the control of TB globally. Controversy has emerged about the best way of confronting MDR-TB in settings with very limited resources. In 1999, the World Health Organization (WHO) created a working group on DOTS-Plus, an initiative exploring the programmatic feasibility and cost-effectiveness of treating MDR-TB in low-income and middle-income countries, in order to consider the management of MDR-TB under programme conditions. The challenges of implementation have proved more daunting than those of access to second-line drugs, the prices of which are dropping. Using data from the WHO/International Union Against Tuberculosis and Lung Disease surveillance project, we have grouped countries according to the proportion of TB patients completing treatment successfully and the level of MDR-TB among previously untreated patients. The resulting matrix provides a reasonable framework for deciding whether to use second-line drugs in a national programme. Countries in which the treatment success rate, i.e. the proportion of new patients who complete the scheduled treatment, irrespective of whether bacteriological cure is documented, is below 70% should give the highest priority to introducing or improving DOTS, the five-point TB control strategy recommended by WHO and the International Union Against Tuberculosis and Lung Disease. A poorly functioning programme can create MDR-TB much faster than it can be treated, even if unlimited resources are available. There is no single prescription for controlling MDR-TB but the various tools available should be applied wisely. Firstly, good DOTS and infection control; then appropriate use of second-line drug treatment. The interval between the two depends on the local context and resources. As funds are allocated to treat MDR-TB, human and financial resources should be increased to expand

  4. Control of shock-wave boundary layer interaction using steady micro-jets

    NASA Astrophysics Data System (ADS)

    Verma, S. B.; Manisankar, C.; Akshara, P.

    2015-09-01

    An experimental investigation was conducted to control the amplitude of shock unsteadiness associated with the interaction induced by a cylindrical protuberance on a flat plate in a Mach 2.18 flow. The control was applied in the form of an array of steady micro air-jets of different configurations with variation in pitch and skew angle of the jets. The effect of air-jet supply pressure on control was also studied. Each of the micro-jet configurations was placed 20 boundary layer thicknesses upstream of the leading edge of the cylinder. The overall interaction is seen to get modified for all control configurations and shows a reduction in both separation- and bow-shock strengths and in triple-point height. A significant reduction in the peak rms value is also observed in the intermittent region of separation for each case. For pitched jets placed in a zig-zag configuration, good control effectiveness is achieved at control pressures similar to the stagnation pressure of the freestream. At higher control pressures, however, their obstruction component increases and if these jets are not spaced sufficiently far apart, the effectiveness of their control begins to drop due to the beginning of spanwise jet-to-jet interaction. On the other hand, pitching or skewing the jets to reduces the obstruction component considerably which at lower control pressures shows lower effectiveness. But at higher control pressure, the effectiveness of these configurations continues to increase unlike the pitched jets.

  5. Effect of Suction on Controlling the Secondary Instability of Boundary Layers

    NASA Technical Reports Server (NTRS)

    El-Hady, Nabil M.

    1990-01-01

    The effect of suction on controlling the 3-D secondary instability is investigated for a boundary layer with pressure gradient in the presence of small but finite amplitude Tollmien-Schlichting wave. The focus is on principal parametric resonance responsible for strong growth of subharmonics in low disturbance environment. Calculations are presented for the effect of suction on the onset and amplification of the secondary instability in Blasius and Falkner-Skan flows, as well as its effect on controlling the production of the vortical structure.

  6. Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.

    PubMed

    Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

    2012-12-21

    In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

  7. Physical-layer energy-efficient receiving method based on selective sampling in orthogonal frequency division multiplexing access passive optical network

    NASA Astrophysics Data System (ADS)

    Li, Jun; He, Hao; Bi, Meihua; Hu, Weisheng

    2014-05-01

    We propose a physical-layer energy-efficient receiving method based on selective sampling in an orthogonal frequency division multiplexing access passive optical network (OFDMA-PON). By using the special designed frame head, the receiver within an optical network unit (ONU) can identify the destination of the incoming frame. The receiver only samples at the time when the destination is in agreement with the ONU, while it stays in standby during the rest of the time. We clarify its feasibility through an experiment and analyze the downstream traffic delay by simulation. The results indicate that under limited delay conditions, ˜60% energy can be saved compared with the traditional receiving method in the OFDMA-PON system with 512 ONUs.

  8. Multi-wavelength lasers fabricated by an Al layer controlled quantum well intermixing technology

    NASA Astrophysics Data System (ADS)

    Teng, J. H.; Chua, S. J.; Huang, Y. H.; Li, G.; Zhang, Z. H.; Helmy, A. Saher; Marsh, J. H.

    2000-09-01

    We report that the shift in the band gap of Al0.3Ga0.7As/GaAs quantum well structures can be precisely controlled by an Al layer buried between a spin-on silica film and a wet-oxidized GaAs surface. The blueshift in wavelength of the Al0.3Ga0.7As/GaAs quantum well photoluminescence (PL) depends linearly on the thickness of the buried Al layer. By changing the Al layer thickness, the PL peak wavelength can be tuned from 7870 Å for the as-grown sample to 7300 and 7050 Å after 20 and 45 s rapid thermal annealing at 850 °C, respectively. Applying this technology, Al layers with different thickness, i.e., no Al, 200 and 300 Å thick, were applied to the oxidized GaAs surface in three adjacent regions with 200 μm spacing on a quantum well laser structure sample. Three wavelength lasers were successfully fabricated in a single chip by a one step rapid thermal annealing. All the lasers have similar threshold current and slope efficiency.

  9. Controlling turbulent boundary layer separation using biologically inspired 2D transverse grooves

    NASA Astrophysics Data System (ADS)

    Lang, Amy; Jones, Emily; Afroz, Farhana

    2013-11-01

    It is theorized that the presence of grooves, such as the sinusoidal ones found on dolphin skin or the cavities that form between bristled shark skin scales, can lead to induced boundary layer mixing and result in the control of turbulent boundary layer separation. To test this hypothesis, a series of water tunnel experiments using DPIV studied the characteristics of a flat plate turbulent boundary layer whereby a rotating cylinder was used to induce an adverse pressure gradient and resulting flow separation. The experiments were repeated with the use of a plate covered with two types of grooves, rectangular and sinusoidal, with a spacing of 2 mm in size. Flow similarity of the cavity flow was preserved between the experiments and flow over bristled shark skin scales. Both geometries resulted in a reduction of flow separation as measured by backflow coefficient. In addition, Reynolds stress profiles showed that as the pressure gradient was increased, the sinusoidal geometry outperformed the rectangular grooves in terms of increased mixing close to the wall. The sinusoidal plate also generated a lower momentum deficit within the boundary layer which would indicate a smaller drag penalty. Support from NSF grant CBET 0932352 and a UA Graduate Council Fellowship is gratefully acknowledged.

  10. Control of electronic properties of 2D carbides (MXenes) by manipulating their transition metal layers

    DOE PAGES

    Anasori, Babak; Shi, Chenyang; Moon, Eun Ju; Xie, Yu; Voigt, Cooper A.; Kent, Paul R. C.; May, Steven J.; Billinge, Simon J. L.; Barsoum, Michel W.; Gogotsi, Yury

    2016-02-24

    In this paper, a transition from metallic to semiconducting-like behavior has been demonstrated in two-dimensional (2D) transition metal carbides by replacing titanium with molybdenum in the outer transition metal (M) layers of M3C2 and M4C3 MXenes. The MXene structure consists of n + 1 layers of near-close packed M layers with C or N occupying the octahedral site between them in an [MX]nM arrangement. Recently, two new families of ordered 2D double transition metal carbides MXenes were discovered, M'2M"C2 and M'2M"2C3 – where M' and M" are two different early transition metals, such as Mo, Cr, Ta, Nb, V, andmore » Ti. The M' atoms only occupy the outer layers and the M" atoms fill the middle layers. In other words, M' atomic layers sandwich the middle M"–C layers. Using X-ray atomic pair distribution function (PDF) analysis on Mo2TiC2 and Mo2Ti2C3 MXenes, we present the first quantitative analysis of structures of these novel materials and experimentally confirm that Mo atoms are in the outer layers of the [MC]nM structures. The electronic properties of these Mo-containing MXenes are compared with their Ti3C2 counterparts, and are found to be no longer metallic-like conductors; instead the resistance increases mildly with decreasing temperatures. Density functional theory (DFT) calculations suggest that OH terminated Mo–Ti MXenes are semiconductors with narrow band gaps. Measurements of the temperature dependencies of conductivities and magnetoresistances have confirmed that Mo2TiC2Tx exhibits semiconductor-like transport behavior, while Ti3C2Tx is a metal. Finally, this finding opens new avenues for the control of the electronic and optical applications of MXenes and for exploring new applications, in which semiconducting properties are required.« less

  11. Coherent Control of the Optical Absorption in a Plasmonic Lattice Coupled to a Luminescent Layer

    NASA Astrophysics Data System (ADS)

    Pirruccio, Giuseppe; Ramezani, Mohammad; Rodriguez, Said Rahimzadeh-Kalaleh; Rivas, Jaime Gómez

    2016-03-01

    We experimentally demonstrate the coherent control, i.e., phase-dependent enhancement and suppression, of the optical absorption in an array of metallic nanoantennas covered by a thin luminescent layer. The coherent control is achieved by using two collinear, counterpropagating, and phase-controlled incident waves with wavelength matching the absorption spectrum of dye molecules coupled to the array. Symmetry arguments shed light on the relation between the relative phase of the incident waves and the excitation efficiency of the optical resonances of the system. This coherent control is associated with a phase-dependent distribution of the electromagnetic near fields in the structure which enables a significant reduction of the unwanted dissipation in the metallic structures.

  12. Coherent Control of the Optical Absorption in a Plasmonic Lattice Coupled to a Luminescent Layer.

    PubMed

    Pirruccio, Giuseppe; Ramezani, Mohammad; Rodriguez, Said Rahimzadeh-Kalaleh; Rivas, Jaime Gómez

    2016-03-11

    We experimentally demonstrate the coherent control, i.e., phase-dependent enhancement and suppression, of the optical absorption in an array of metallic nanoantennas covered by a thin luminescent layer. The coherent control is achieved by using two collinear, counterpropagating, and phase-controlled incident waves with wavelength matching the absorption spectrum of dye molecules coupled to the array. Symmetry arguments shed light on the relation between the relative phase of the incident waves and the excitation efficiency of the optical resonances of the system. This coherent control is associated with a phase-dependent distribution of the electromagnetic near fields in the structure which enables a significant reduction of the unwanted dissipation in the metallic structures. PMID:27015478

  13. Active Control of Turbulent Boundary Layer Induced Sound Radiation from Multiple Aircraft Panels

    NASA Technical Reports Server (NTRS)

    Gibbs, Gary P.; Cabell, Randolph H.

    2002-01-01

    The objective of this work is to experimentally investigate active structural acoustic control of turbulent boundary layer (TBL) induced sound radiation from multiple panels on an aircraft sidewall. One possible approach for controlling sound radiation from multiple panels is a multi-input/multi-output scheme which considers dynamic coupling between the panels. Unfortunately, this is difficult for more than a few panels, and is impractical for a typical aircraft which contains several hundred such panels. An alternative is to implement a large number of independent control systems. Results from the current work demonstrate the feasibility of reducing broadband radiation from multiple panels utilizing a single-input/single-output (SISO) controller per bay, and is the first known demonstration of active control of TBL induced sound radiation on more than two bays simultaneously. The paper compares sound reduction for fully coupled control of six panels versus independent control on each panel. An online adaptive control scheme for independent control is also demonstrated. This scheme will adjust for slow time varying dynamic systems such as fuselage response changes due to aircraft pressurization, etc.

  14. The IEO Data Center Management System: Tools for quality control, analysis and access marine data

    NASA Astrophysics Data System (ADS)

    Casas, Antonia; Garcia, Maria Jesus; Nikouline, Andrei

    2010-05-01

    Since 1994 the Data Centre of the Spanish Oceanographic Institute develops system for archiving and quality control of oceanographic data. The work started in the frame of the European Marine Science & Technology Programme (MAST) when a consortium of several Mediterranean Data Centres began to work on the MEDATLAS project. Along the years, old software modules for MS DOS were rewritten, improved and migrated to Windows environment. Oceanographic data quality control includes now not only vertical profiles (mainly CTD and bottles observations) but also time series of currents and sea level observations. New powerful routines for analysis and for graphic visualization were added. Data presented originally in ASCII format were organized recently in an open source MySQL database. Nowadays, the IEO, as part of SeaDataNet Infrastructure, has designed and developed a new information system, consistent with the ISO 19115 and SeaDataNet standards, in order to manage the large and diverse marine data and information originated in Spain by different sources, and to interoperate with SeaDataNet. The system works with data stored in ASCII files (MEDATLAS, ODV) as well as data stored within the relational database. The components of the system are: 1.MEDATLAS Format and Quality Control - QCDAMAR: Quality Control of Marine Data. Main set of tools for working with data presented as text files. Includes extended quality control (searching for duplicated cruises and profiles, checking date, position, ship velocity, constant profiles, spikes, density inversion, sounding, acceptable data, impossible regional values,...) and input/output filters. - QCMareas: A set of procedures for the quality control of tide gauge data according to standard international Sea Level Observing System. These procedures include checking for unexpected anomalies in the time series, interpolation, filtering, computation of basic statistics and residuals. 2. DAMAR: A relational data base (MySql) designed to

  15. Controlled synthesis of layered double hydroxide nanoplates driven by screw dislocations.

    PubMed

    Forticaux, Audrey; Dang, Lianna; Liang, Hanfeng; Jin, Song

    2015-05-13

    Layered double hydroxides (LDHs) are a family of two-dimensional (2D) materials with layered crystal structures that have found many applications. Common strategies to synthesize LDHs lead to a wide variety of morphologies, from discrete 2D nanosheets to nanoflowers. Here, we report a study of carefully controlled LDH nanoplate syntheses using zinc aluminum (ZnAl) and cobalt aluminum (CoAl) LDHs as examples and reveal their crystal growth to be driven by screw dislocations. By controlling and maintaining a low precursor supersaturation using a continuous flow reactor, individual LDH nanoplates with well-defined morphologies were synthesized on alumina-coated substrates, instead of the nanoflowers that result from uncontrolled overgrowth. The dislocation-driven growth was further established for LDH nanoplates directly synthesized using the respective metal salt precursors. Atomic force microscopy revealed screw dislocation growth spirals, and under transmission electron microscopy, thin CoAl LDH nanoplates displayed complex contrast contours indicative of strong lattice strain caused by dislocations. These results suggest the dislocation-driven mechanism is generally responsible for the growth of 2D LDH nanostructures, and likely other materials with layered crystal structures, which could help the rational synthesis of well-defined 2D nanomaterials with improved properties.

  16. Correlation of anomalous write error rates and ferromagnetic resonance spectrum in spin-transfer-torque-magnetic-random-access-memory devices containing in-plane free layers

    SciTech Connect

    Evarts, Eric R.; Rippard, William H.; Pufall, Matthew R.; Heindl, Ranko

    2014-05-26

    In a small fraction of magnetic-tunnel-junction-based magnetic random-access memory devices with in-plane free layers, the write-error rates (WERs) are higher than expected on the basis of the macrospin or quasi-uniform magnetization reversal models. In devices with increased WERs, the product of effective resistance and area, tunneling magnetoresistance, and coercivity do not deviate from typical device properties. However, the field-swept, spin-torque, ferromagnetic resonance (FS-ST-FMR) spectra with an applied DC bias current deviate significantly for such devices. With a DC bias of 300 mV (producing 9.9 × 10{sup 6} A/cm{sup 2}) or greater, these anomalous devices show an increase in the fraction of the power present in FS-ST-FMR modes corresponding to higher-order excitations of the free-layer magnetization. As much as 70% of the power is contained in higher-order modes compared to ≈20% in typical devices. Additionally, a shift in the uniform-mode resonant field that is correlated with the magnitude of the WER anomaly is detected at DC biases greater than 300 mV. These differences in the anomalous devices indicate a change in the micromagnetic resonant mode structure at high applied bias.

  17. Two-layer wireless distributed sensor/control network based on RF

    NASA Astrophysics Data System (ADS)

    Feng, Li; Lin, Yuchi; Zhou, Jingjing; Dong, Guimei; Xia, Guisuo

    2006-11-01

    A project of embedded Wireless Distributed Sensor/Control Network (WDSCN) based on RF is presented after analyzing the disadvantages of traditional measure and control system. Because of high-cost and complexity, such wireless techniques as Bluetooth and WiFi can't meet the needs of WDSCN. The two-layer WDSCN is designed based on RF technique, which operates in the ISM free frequency channel with low power and high transmission speed. Also the network is low cost, portable and moveable, integrated with the technologies of computer network, sensor, microprocessor and wireless communications. The two-layer network topology is selected in the system; a simple but efficient self-organization net protocol is designed to fit the periodic data collection, event-driven and store-and-forward. Furthermore, adaptive frequency hopping technique is adopted for anti-jamming apparently. The problems about power reduction and synchronization of data in wireless system are solved efficiently. Based on the discussion above, a measure and control network is set up to control such typical instruments and sensors as temperature sensor and signal converter, collect data, and monitor environmental parameters around. This system works well in different rooms. Experiment results show that the system provides an efficient solution to WDSCN through wireless links, with high efficiency, low power, high stability, flexibility and wide working range.

  18. Injection slot location for boundary-layer control in shock-induced separation

    NASA Technical Reports Server (NTRS)

    Viswanath, P. R.; Sankaran, L.; Sagdeo, P. M.; Narasimha, R.; Prabhu, A.

    1978-01-01

    An experimental investigation of the effect of tangential air injection, when the injection slot is located inside of what would otherwise have been the dead air zone in a separated flow, in controlling shock-induced turbulent boundary layer separation is presented. The experiments were carried out at a free-stream Mach number of 2.5 in the separated flow induced by a compression corner with a 20 deg angle. The observations made were wall static pressures, pitot profiles, and schlieren visualizations of the flow. The results show that the present location for injection is more effective in suppressing boundary-layer separation than the more conventional one, where the slot is located upstream of where separation would occur in the absence of injection.

  19. Local and Distant Input Controlling Excitation in Layer II of the Medial Entorhinal Cortex.

    PubMed

    Fuchs, Elke C; Neitz, Angela; Pinna, Roberta; Melzer, Sarah; Caputi, Antonio; Monyer, Hannah

    2016-01-01

    Layer II (LII) of the medial entorhinal cortex (MEC) comprises grid cells that support spatial navigation. The firing pattern of grid cells might be explained by attractor dynamics in a network, which requires either direct excitatory connectivity between phase-specific grid cells or indirect coupling via interneurons. However, knowledge regarding local networks that support in vivo activity is incomplete. Here we identified essential components of LII networks in the MEC. We distinguished four types of excitatory neurons that exhibit cell-type-specific local excitatory and inhibitory connectivity. Furthermore, we found that LII neurons contribute to the excitation of contralateral neurons in the corresponding layer. Finally, we demonstrated that the medial septum controls excitation in the MEC via two subpopulations of long-range GABAergic neurons that target distinct interneurons in LII, thereby disinhibiting local circuits. We thus identified local connections that could support attractor dynamics and external inputs that likely govern excitation in LII. PMID:26711115

  20. Powder Layer Preparation Using Vibration-controlled Capillary Steel Nozzles for Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Stichel, Thomas; Laumer, Tobias; Baumüller, Tobias; Amend, Philipp; Roth, Stephan

    In this report, the dry delivery of polyamide 12 powders by vibrating capillary steel nozzles is investigated and discussed regarding its potential for powder layer preparation in Laser Beam Melting. Therefore, a setup including a steel nozzle assembled on a piezoelectric actuator is presented, which enables the precise control over very small powder quantities by vibration excitation. An analysis reveals that the mass flow through the nozzle can be adjusted by the vibration modes in a certain range depending on the nozzle's specifications, whereas the vibration modes themselves show a complicated behaviour. Using a positioning system in combination with the vibrating nozzle, single-layer patterns consisting of polyamide 12 are produced and characterized regarding surface homogeneity and selectivity using a laser stripe sensor.

  1. A Comparison of Active and Passive Methods for Control of Hypersonic Boundary Layers on Airbreathing Configurations

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Nowak, Robert J.

    2003-01-01

    Active and passive methods for control of hypersonic boundary layers have been experimentally examined in NASA Langley Research Center wind tunnels on a Hyper-X model. Several configurations for forcing transition using passive discrete roughness elements and active mass addition, or blowing, methods were compared in two hypersonic facilities, the 20-Inch Mach 6 Air and the 31-Inch Mach 10 Air tunnels. Heat transfer distributions, obtained via phosphor thermography, shock system details, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. The comparisons between the active and passive methods for boundary layer control were conducted at test conditions that nearly match the nominal Mach 7 flight trajectory of an angle-of-attack of 2-deg and length Reynolds number of 5.6 million. For the passive roughness examination, the primary parametric variation was a range of trip heights within the calculated boundary layer thickness for several trip concepts. The prior passive roughness study resulted in a swept ramp configuration being selected for the Mach 7 flight vehicle that was scaled to be roughly 0.6 of the calculated boundary layer thickness. For the active jet blowing study, the blowing manifold pressure was systematically varied for each configuration, while monitoring the mass flow, to determine the jet penetration height with schlieren and transition movement with the phosphor system for comparison to the passive results. All the blowing concepts tested were adequate for providing transition onset near the trip location with manifold stagnation pressures on the order of 40 times the model static pressure or higher.

  2. Layer-Controlled Chemical Vapor Deposition Growth of MoS2 Vertical Heterostructures via van der Waals Epitaxy.

    PubMed

    Samad, Leith; Bladow, Sage M; Ding, Qi; Zhuo, Junqiao; Jacobberger, Robert M; Arnold, Michael S; Jin, Song

    2016-07-26

    The fascinating semiconducting and optical properties of monolayer and few-layer transition metal dichalcogenides, as exemplified by MoS2, have made them promising candidates for optoelectronic applications. Controllable growth of heterostructures based on these layered materials is critical for their successful device applications. Here, we report a direct low temperature chemical vapor deposition (CVD) synthesis of MoS2 monolayer/multilayer vertical heterostructures with layer-controlled growth on a variety of layered materials (SnS2, TaS2, and graphene) via van der Waals epitaxy. Through precise control of the partial pressures of the MoCl5 and elemental sulfur precursors, reaction temperatures, and careful tracking of the ambient humidity, we have successfully and reproducibly grown MoS2 vertical heterostructures from 1 to 6 layers over a large area. The monolayer MoS2 heterostructure was verified using cross-sectional high resolution transmission electron microscopy (HRTEM) while Raman and photoluminescence spectroscopy confirmed the layer-controlled MoS2 growth and heterostructure electronic interactions. Raman, photoluminescence, and energy dispersive X-ray spectroscopy (EDS) mappings verified the uniform coverage of the MoS2 layers. This reaction provides an ideal method for the scalable layer-controlled growth of transition metal dichalcogenide heterostructures via van der Waals epitaxy for a variety of optoelectronic applications. PMID:27373305

  3. Layer-Controlled Chemical Vapor Deposition Growth of MoS2 Vertical Heterostructures via van der Waals Epitaxy.

    PubMed

    Samad, Leith; Bladow, Sage M; Ding, Qi; Zhuo, Junqiao; Jacobberger, Robert M; Arnold, Michael S; Jin, Song

    2016-07-26

    The fascinating semiconducting and optical properties of monolayer and few-layer transition metal dichalcogenides, as exemplified by MoS2, have made them promising candidates for optoelectronic applications. Controllable growth of heterostructures based on these layered materials is critical for their successful device applications. Here, we report a direct low temperature chemical vapor deposition (CVD) synthesis of MoS2 monolayer/multilayer vertical heterostructures with layer-controlled growth on a variety of layered materials (SnS2, TaS2, and graphene) via van der Waals epitaxy. Through precise control of the partial pressures of the MoCl5 and elemental sulfur precursors, reaction temperatures, and careful tracking of the ambient humidity, we have successfully and reproducibly grown MoS2 vertical heterostructures from 1 to 6 layers over a large area. The monolayer MoS2 heterostructure was verified using cross-sectional high resolution transmission electron microscopy (HRTEM) while Raman and photoluminescence spectroscopy confirmed the layer-controlled MoS2 growth and heterostructure electronic interactions. Raman, photoluminescence, and energy dispersive X-ray spectroscopy (EDS) mappings verified the uniform coverage of the MoS2 layers. This reaction provides an ideal method for the scalable layer-controlled growth of transition metal dichalcogenide heterostructures via van der Waals epitaxy for a variety of optoelectronic applications.

  4. Controlling the taste receptor accessible structure of rebaudioside A via binding to bovine serum albumin.

    PubMed

    Mudgal, Samriddh; Keresztes, Ivan; Feigenson, Gerald W; Rizvi, S S H

    2016-04-15

    We illustrate a method that uses bovine serum albumin (BSA) to control the receptor-accessible part of rebaudioside A (Reb A). The critical micelle concentration (CMC) of Reb A was found to be 4.5 mM and 5 mM at pH 3 and 6.7 respectively. NMR studies show that below its CMC, Reb A binds weakly to BSA to generate a Reb A-protein complex ("RPC"), which is only modestly stable under varying conditions of pH (3.0-6.7) and temperature (4-40°C) with its binding affinities determined to be in the range of 5-280 mM. Furthermore, saturation transfer difference (STD) NMR experiments confirm that the RPC has fast exchange of the bitterness-instigating diterpene of Reb A into the binding sites of BSA. Our method can be used to alter the strength of Reb A-receptor interaction, as a result of binding of Reb A to BSA, which may ultimately lead to moderation of its taste.

  5. Peptide-controlled access to the interior surface of empty virus nanoparticles.

    PubMed

    Sainsbury, Frank; Saunders, Keith; Aljabali, Alaa A A; Evans, David J; Lomonossoff, George P

    2011-11-01

    The structure of Cowpea mosaic virus (CPMV) is known to high resolution, thereby enabling the rational use of the particles in diverse applications, from vaccine design to nanotechnology. A recently devised method for the production of empty virus-like particles (eVLPs) has opened up new possibilities for CPMV capsid-based technologies, such as internal mineralisation of the particle. We have investigated the role of the carboxyl (C) terminus of the small coat (S) protein in controlling access to the interior of CPMV eVLPs by determining the efficiency of internal mineralisation. The presence of the C-terminal 24-amino acid peptide of the S protein was found to inhibit internal mineralisation, an effect that could be eliminated by enzymatic removal of this region. We have also demonstrated the amenability of the C terminus to genetic modification. Substitution with six histidine residues generated stable particles and facilitated external mineralisation by cobalt. These findings demonstrate consistent internal and external mineralisation of CPMV, and will aid the further exploration and development of the use of eVLPs for bionanotechnological and medical applications.

  6. Towards human-centric visual access control for clinical data management.

    PubMed

    Fahl, Sascha; Harbach, Marian; Smith, Matthew

    2012-01-01

    We propose a novel human-centric, visual, and context-aware access control (AC) system for distributed clinical data management and health information systems. Human-centricity in this context means that medical staff should be able to configure AC rules, both in a timesaving and reliable manner. Since medical data often includes (meta-) information about a patient, it is essential that an AC system includes the patient into the AC process. To cater for the strong security needs in the medical domain, both the AC policy creation by medical staff as well as the patient-interaction feature need to be taken into account. While traditional AC systems offer sufficient security in theory, they lack in comfort and flexibility and as a result find no widespread acceptance with non tech-savvy users. Distributed medical institutions could enormously benefit from the opportunity of dynamic AC configuration at an end-user level while adhering to legal, ethical or other privacy requirements. Hence, this paper presents a human-centric visual AC model for medical data, addressing usability, information security and patient interaction. PMID:22874293

  7. Controlling the taste receptor accessible structure of rebaudioside A via binding to bovine serum albumin.

    PubMed

    Mudgal, Samriddh; Keresztes, Ivan; Feigenson, Gerald W; Rizvi, S S H

    2016-04-15

    We illustrate a method that uses bovine serum albumin (BSA) to control the receptor-accessible part of rebaudioside A (Reb A). The critical micelle concentration (CMC) of Reb A was found to be 4.5 mM and 5 mM at pH 3 and 6.7 respectively. NMR studies show that below its CMC, Reb A binds weakly to BSA to generate a Reb A-protein complex ("RPC"), which is only modestly stable under varying conditions of pH (3.0-6.7) and temperature (4-40°C) with its binding affinities determined to be in the range of 5-280 mM. Furthermore, saturation transfer difference (STD) NMR experiments confirm that the RPC has fast exchange of the bitterness-instigating diterpene of Reb A into the binding sites of BSA. Our method can be used to alter the strength of Reb A-receptor interaction, as a result of binding of Reb A to BSA, which may ultimately lead to moderation of its taste. PMID:26616927

  8. The SH2 domain of Abl kinases regulates kinase autophosphorylation by controlling activation loop accessibility

    NASA Astrophysics Data System (ADS)

    Lamontanara, Allan Joaquim; Georgeon, Sandrine; Tria, Giancarlo; Svergun, Dmitri I.; Hantschel, Oliver

    2014-11-01

    The activity of protein kinases is regulated by multiple molecular mechanisms, and their disruption is a common driver of oncogenesis. A central and almost universal control element of protein kinase activity is the activation loop that utilizes both conformation and phosphorylation status to determine substrate access. In this study, we use recombinant Abl tyrosine kinases and conformation-specific kinase inhibitors to quantitatively analyse structural changes that occur after Abl activation. Allosteric SH2-kinase domain interactions were previously shown to be essential for the leukemogenesis caused by the Bcr-Abl oncoprotein. We find that these allosteric interactions switch the Abl activation loop from a closed to a fully open conformation. This enables the trans-autophosphorylation of the activation loop and requires prior phosphorylation of the SH2-kinase linker. Disruption of the SH2-kinase interaction abolishes activation loop phosphorylation. Our analysis provides a molecular mechanism for the SH2 domain-dependent activation of Abl that may also regulate other tyrosine kinases.

  9. Guaranteeing synchronous message deadlines with the timed token medium access control protocol

    NASA Technical Reports Server (NTRS)

    Agrawal, Gopal; Chen, Baio; Zhao, Wei; Davari, Sadegh

    1992-01-01

    We study the problem of guaranteeing synchronous message deadlines in token ring networks where the timed token medium access control protocol is employed. Synchronous capacity, defined as the maximum time for which a node can transmit its synchronous messages every time it receives the token, is a key parameter in the control of synchronous message transmission. To ensure the transmission of synchronous messages before their deadlines, synchronous capacities must be properly allocated to individual nodes. We address the issue of appropriate allocation of the synchronous capacities. Several synchronous capacity allocation schemes are analyzed in terms of their ability to satisfy deadline constraints of synchronous messages. We show that an inappropriate allocation of the synchronous capacities could cause message deadlines to be missed even if the synchronous traffic is extremely low. We propose a scheme called the normalized proportional allocation scheme which can guarantee the synchronous message deadlines for synchronous traffic of up to 33 percent of available utilization. To date, no other synchronous capacity allocation scheme has been reported to achieve such substantial performance. Another major contribution of this paper is an extension to the previous work on the bounded token rotation time. We prove that the time elapsed between any consecutive visits to a particular node is bounded by upsilon TTRT, where TTRT is the target token rotation time set up at system initialization time. The previous result by Johnson and Sevcik is a special case where upsilon = 2. We use this result in the analysis of various synchronous allocation schemes. It can also be applied in other similar studies.

  10. Integrated, nonvolatile, high-speed analog random access memory

    NASA Technical Reports Server (NTRS)

    Katti, Romney R. (Inventor); Wu, Jiin-Chuan (Inventor); Stadler, Henry L. (Inventor)

    1994-01-01

    This invention provides an integrated, non-volatile, high-speed random access memory. A magnetically switchable ferromagnetic or ferrimagnetic layer is sandwiched between an electrical conductor which provides the ability to magnetize the magnetically switchable layer and a magneto resistive or Hall effect material which allows sensing the magnetic field which emanates from the magnetization of the magnetically switchable layer. By using this integrated three-layer form, the writing process, which is controlled by the conductor, is separated from the storage medium in the magnetic layer and from the readback process which is controlled by the magnetoresistive layer. A circuit for implementing the memory in CMOS or the like is disclosed.

  11. An Ounce of Prevention: Technologists Use Network-Access Control to Protect System Resources, Students

    ERIC Educational Resources Information Center

    Bolch, Matt

    2009-01-01

    Whether for an entire district, a single campus, or one classroom, allowing authorized access to a computer network can be fraught with challenges. The login process should be fairly seamless to approved users, giving them speedy access to approved Web sites, databases, and other sources of information. It also should be tough on unauthorized…

  12. Open-loop control of noise amplification in a separated boundary layer flow

    SciTech Connect

    Boujo, E. Gallaire, F.; Ehrenstein, U.

    2013-12-15

    Linear optimal gains are computed for the subcritical two-dimensional separated boundary-layer flow past a bump. Very large optimal gain values are found, making it possible for small-amplitude noise to be strongly amplified and to destabilize the flow. The optimal forcing is located close to the summit of the bump, while the optimal response is the largest in the shear layer. The largest amplification occurs at frequencies corresponding to eigenvalues which first become unstable at higher Reynolds number. Nonlinear direct numerical simulations show that a low level of noise is indeed sufficient to trigger random flow unsteadiness, characterized here by large-scale vortex shedding. Next, a variational technique is used to compute efficiently the sensitivity of optimal gains to steady control (through source of momentum in the flow, or blowing/suction at the wall). A systematic analysis at several frequencies identifies the bump summit as the most sensitive region for control with wall actuation. Based on these results, a simple open-loop control strategy is designed, with steady wall suction at the bump summit. Linear calculations on controlled base flows confirm that optimal gains can be drastically reduced at all frequencies. Nonlinear direct numerical simulations also show that this control allows the flow to withstand a higher level of stochastic noise without becoming nonlinearly unstable, thereby postponing bypass transition. In the supercritical regime, sensitivity analysis of eigenvalues supports the choice of this control design. Full restabilization of the flow is obtained, as evidenced by direct numerical simulations and linear stability analysis.

  13. Numerical study of wingtip shed vorticity reduction by wing Boundary Layer Control

    NASA Astrophysics Data System (ADS)

    Posada, Jose Alejandro

    Wingtip vortex reductions have been obtained by Boundary Layer Control application to an AR=1.5 rectangular wing using a NACA 0012 airfoil. If wingtip shed vorticity could be reduced significantly, then so would induced drag resulting in improved cruise fuel economy. Power savings would be even more impressive at low flight speed or in climb. A two dimensional wing produces lift without wingtip vorticity. Its bound vorticity, Gamma, equals the contour integral of the boundary layer vorticity gamma or Gamma = ∮gamma · dl. Where the upper and lower boundary layers meet at the cusped TE, their local static pressure pu=pl then the boundary layer outer edge inviscid velocity Vupper=Vlower and gammalower=-gamma upper. This explains the 2-D wing self cancellation of the upper and lower surface boundary layer vorticity when they meet upon shedding at the trailing edge. In finite wings, the presence of spanwise pressure gradients near the wing tips misaligns gammalower and gammaupper at the wingtip TE preventing the upper and lower surface boundary layers from completely canceling each other. To prevent them from generating wing tip vortices, the local boundary layers need to be captured in suction slots. Once vorticity is captured, it can be eliminated by viscous mixing prior to venting over board. The objective of this dissertation was to use a commercial Computational Fluid Dynamics code (Fluent) to search for the best configuration to locate BLC suction slots to capture non-parallel boundary layer vorticity prior to shedding near the wingtips. The configuration selected for running the simulations was tested by trying to duplicate a 3D wing for which sufficient experimental and computational models by others are available. The practical case selected was done by Chow et al in the 32 x 48 in. low speed wind tunnel at the Fluid Mechanics Laboratory of NASA Ames Research Center, and computationally analyzed by Dacles-Mariani et al, and Khim and Rhee. The present

  14. Blended Wing Body Systems Studies: Boundary Layer Ingestion Inlets With Active Flow Control

    NASA Technical Reports Server (NTRS)

    Geiselhart, Karl A. (Technical Monitor); Daggett, David L.; Kawai, Ron; Friedman, Doug

    2003-01-01

    A CFD analysis was performed on a Blended Wing Body (BWB) aircraft with advanced, turbofan engines analyzing various inlet configurations atop the aft end of the aircraft. The results are presented showing that the optimal design for best aircraft fuel efficiency would be a configuration with a partially buried engine, short offset diffuser using active flow control, and a D-shaped inlet duct that partially ingests the boundary layer air in flight. The CFD models showed that if active flow control technology can be satisfactorily developed, it might be able to control the inlet flow distortion to the engine fan face and reduce the powerplant performance losses to an acceptable level. The weight and surface area drag benefits of a partially submerged engine shows that it might offset the penalties of ingesting the low energy boundary layer air. The combined airplane performance of such a design might deliver approximately 5.5% better aircraft fuel efficiency over a conventionally designed, pod-mounted engine.

  15. Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

    SciTech Connect

    Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki; Kalita, Golap

    2014-09-29

    Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

  16. An Integrated Observational and Model Synthesis Approach to Examine Dominant Environmental Controls on Active Layer Thickness

    NASA Astrophysics Data System (ADS)

    Atchley, A. L.; Coon, E.; Painter, S. L.; Harp, D. R.; Wilson, C. J.

    2015-12-01

    The active layer thickness (ALT) - the annual maximum depth of soil with above 0°C temperatures - in part determines the volume of carbon-rich stores available for decomposition and therefore potential greenhouse gas release into the atmosphere from Arctic tundra. However, understanding and predicting ALT in polygonal tundra landscapes is difficult due to the complex nature of hydrothermal atmospheric-surface-subsurface interactions in freezing/thawing soil. Simply deconvolving effects of single environmental controls on ALT is not possible with measurements alone as processes act in concert to drive thaw depth formation. Process-rich models of thermal hydrological dynamics, conversely, are a valuable tool for understanding the dominant controls and uncertainties in predicting permafrost conditions. By integrating observational data with known physical relationships to form process-rich models, synthetic experiments can then be used to explore a breadth of environmental conditions encountered and the effect of each environmental attribute may be assessed. Here a process rich thermal hydrology model, The Advanced Terrestrial Simulator, has been created and calibrated using observed data from Barrow, AK. An ensemble of 1D thermal hydrologic models were simulated that span a range of three environmental factors 1) thickness of organic rich soil, 2) snow depth, and 3) soil moisture content, to investigate the role of each factor on ALT. Results show that organic layer thickness acts as a strong insulator and is the dominant control of ALT, but the strength of the effect of organic layer thickness is also dependent on the saturation state. Using the ensemble results, the effect of peat thickness on ALT was then examined on a 2D domain. This work was supported by LANL Laboratory Directed Research and Development Project LDRD201200068DR and by the The Next-Generation Ecosystem Experiments (NGEE Arctic) project. NGEE-Arctic is supported by the Office of Biological and

  17. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    SciTech Connect

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-15

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO{sub 3}{sup 2−} solutions imply that Mg{sub 3}Al–VC LDH is a better controlled release system than Mg{sub 3}Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO{sub 3}{sup 2−} solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO{sub 3}{sup 2−} solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO{sub 3}{sup 2−} solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO{sub 3}{sup 2−} solution.

  18. The design and performance of axially symmetrical contoured wall diffusers employing suction boundary layer control

    NASA Technical Reports Server (NTRS)

    Nelson, C. D., Jr.; Hudson, W. G.; Yang, T.

    1974-01-01

    This paper presents a procedure for the design and the performance prediction of axially symmetrical contoured wall diffusers employing suction boundary layer control. An inverse problem approach was used in the potential flow design of the diffuser wall contours. The experimentally observed flow characteristics and the stability of flows within the diffuser are also described. Guidelines for the design of low suction (less than 10 percent of the inlet flow) and thus high effectiveness contoured wall diffusers are also provided based on the results of the experimental program.

  19. Suppressing NOM access to controlled porous TiO2 particles enhances the decomposition of target water contaminants

    EPA Science Inventory

    Suppressing access of natural organic matter (NOM) to TiO2 is a key to the successful photocatalytic decomposition of a target contaminant in water. This study first demonstrates simply controlling the porous structure of TiO2 can significantly improve the selective oxidation.

  20. On-Line Remote Catalog Access and Circulation Control System. Part I: Functional Specifications. Part II: User's Manual.

    ERIC Educational Resources Information Center

    International Business Machines Corp., Gaithersburg, MD. Data Processing Div.

    The Ohio State University Libraries On-line Remote Catalog Access and Circulation Control System (LCS) began on-line operations with the conversion of one department library in November 1970. By December all 26 libraries had been converted to the automated system and LCS was fully operational one month ahead of schedule. LCS is designed as a…

  1. Stability of organic carbon in deep soil layers controlled by fresh carbon supply.

    PubMed

    Fontaine, Sébastien; Barot, Sébastien; Barré, Pierre; Bdioui, Nadia; Mary, Bruno; Rumpel, Cornelia

    2007-11-01

    The world's soils store more carbon than is present in biomass and in the atmosphere. Little is known, however, about the factors controlling the stability of soil organic carbon stocks and the response of the soil carbon pool to climate change remains uncertain. We investigated the stability of carbon in deep soil layers in one soil profile by combining physical and chemical characterization of organic carbon, soil incubations and radiocarbon dating. Here we show that the supply of fresh plant-derived carbon to the subsoil (0.6-0.8 m depth) stimulated the microbial mineralization of 2,567 +/- 226-year-old carbon. Our results support the previously suggested idea that in the absence of fresh organic carbon, an essential source of energy for soil microbes, the stability of organic carbon in deep soil layers is maintained. We propose that a lack of supply of fresh carbon may prevent the decomposition of the organic carbon pool in deep soil layers in response to future changes in temperature. Any change in land use and agricultural practice that increases the distribution of fresh carbon along the soil profile could however stimulate the loss of ancient buried carbon.

  2. Boundary Layer Flow Control by an Array of Ramp-Shaped Vortex Generators

    NASA Technical Reports Server (NTRS)

    Zaman, K. B. M. Q.; Hirt, S. M.; Bencic, T. J.

    2012-01-01

    Flow field survey results for the effect of ramp-shaped vortex generators (VG) on a turbulent boundary layer are presented. The experiments are carried out in a low-speed wind tunnel and the data are acquired primarily by hot-wire anemometry. Distributions of mean velocity and turbulent stresses as well as streamwise vorticity, on cross-sectional planes at various downstream locations, are obtained. These detailed flow field properties, including the boundary layer characteristics, are documented with the primary objective of aiding possible computational investigations. The results show that VG orientation with apex upstream, that produces a downwash directly behind it, yields a stronger pair of streamwise vortices. This is in contrast to the case with apex downstream that produces a pair of vortices of opposite sense. Thus, an array of VG s with the former orientation, usually considered for film-cooling application, may also be superior for mixing enhancement and boundary layer separation control. The data files can be found on a supplemental CD.

  3. Boundary Layer Flow Control by an Array of Ramp-Shaped Vortex Generators

    NASA Technical Reports Server (NTRS)

    Zaman, K. B. M. Q.; Hirt, S. M.; Bencic, T. J.

    2012-01-01

    Flow field survey results for the effect of ramp-shaped vortex generators (VG) on a turbulent boundary layer are presented. The experiments are carried out in a low-speed wind tunnel and the data are acquired primarily by hot-wire anemometry. Distributions of mean velocity and turbulent stresses as well as streamwise vorticity, on cross-sectional planes at various downstream locations, are obtained. These detailed flow field properties, including the boundary layer characteristics, are documented with the primary objective of aiding possible computational investigations. The results show that VG orientation with apex upstream, that produces a downwash directly behind it, yields a stronger pair of streamwise vortices. This is in contrast to the case with apex downstream that produces a pair of vortices of opposite sense. Thus, an array of VG s with the former orientation, usually considered for film-cooling application, may also be superior for mixing enhancement and boundary layer separation control. (See CASI ID 20120009374 for Supplemental CD-ROM.)

  4. Anticancer nanodelivery system with controlled release property based on protocatechuate–zinc layered hydroxide nanohybrid

    PubMed Central

    Barahuie, Farahnaz; Hussein, Mohd Zobir; Abd Gani, Shafinaz; Fakurazi, Sharida; Zainal, Zulkarnain

    2014-01-01

    Background We characterize a novel nanocomposite that acts as an efficient anticancer agent. Methods This nanocomposite consists of zinc layered hydroxide intercalated with protocatechuate (an anionic form of protocatechuic acid), that has been synthesized using a direct method with zinc oxide and protocatechuic acid as precursors. Results The resulting protocatechuic acid nanocomposite (PAN) showed a basal spacing of 12.7 Å, indicating that protocatechuate was intercalated in a monolayer arrangement, with an angle of 54° from the Z-axis between the interlayers of the zinc layered hydroxide, and an estimated drug loading of about 35.7%. PAN exhibited the properties of a mesoporous type material, with greatly enhanced thermal stability of protocatechuate as compared to its free counterpart. The presence of protocatechuate in the interlayers of the zinc layered hydroxide was further supported by Fourier transform infrared spectroscopy. Protocatechuate was released from PAN in a slow and sustained manner. This mechanism of release was well represented by a pseudo-second order kinetics model. PAN has shown increased cytotoxicity compared to the free form of protocatechuic acid in all cancer cell lines tested. Tumor growth suppression was extensive, particularly in HepG2 and HT29 cell lines. Conclusion PAN is suitable for use as a controlled release formulation, and our in vitro evidence indicates that PAN is an effective anticancer agent. PAN may have potential as a chemotherapeutic drug for human cancer. PMID:25061291

  5. Controlled synthesis of single-layer MoSe2 nanostructures

    NASA Astrophysics Data System (ADS)

    Chen, Yuxuan; Zhang, Chendong; Cui, Ping; Zhang, Zhenyu; Shih, Chih-Kang

    Group VIB transition metal dichalcogenides (TMD), such as MoSe2, WS2, etc., are a family of layered materials with weak van der Waals (vdW) interaction between neighboring layers. A transition from indirect to direct bandgap semiconductor takes place for most of these materials when they become single layer (SL), and the values of these direct band gap are comparable to visible light. This makes SL TMDs attractive candidates for 2D electronic and optoelectronic devices. Though epitaxial SL TMDs have been successfully prepared, there is controversy in their growth conditions and in their edge structures. Moreover, some intriguing theoretical predictions about the finite-size effect on SL TMDs are still awaiting experimental proof. Here we report systematic studies of the thermodynamics/ kinetics of SL MoSe2 formation on a vdW surface (namely, highly oriented pyrolytic graphite) using molecular beam epitaxy (MBE). We also report the controlled creation of various nanostructures of MBE SL MoSe2. The edge properties and the influence of the in-plane confinement on the electronic structure are addressed by in-situ STM and STS. Theoretical calculations have been carried out to help understanding the experimental discoveries. Corresponding author.

  6. How does Reelin control neuronal migration and layer formation in the developing mammalian neocortex?

    PubMed

    Sekine, Katsutoshi; Kubo, Ken-ichiro; Nakajima, Kazunori

    2014-09-01

    The mammalian neocortex has a laminar structure that develops in a birth-date-dependent "inside-out" pattern. Its layered structure is established by neuronal migration accompanied by sequential changes in migratory mode regulated by several signaling cascades. Although Reelin was discovered about two decades ago and is one of the best known molecules that is indispensable to the establishment of the "inside-out" neuron layers, the cellular and molecular functions of Reelin in layer formation are still largely unknown. In this review article, we summarize our recent understanding of Reelin's functions during neuronal migration. Reelin acts in at least two different steps of neuronal migration: the final step of neuronal migration (somal/terminal translocation) just beneath the marginal zone (MZ) and the regulation of cell polarity step when the neurons change their migratory mode from multipolar migration to locomotion. During the translocation mode, Reelin activates integrin α5β1 through an intracellular pathway that triggers the translocation and activates N-cadherin in concert with the nectin-afadin system. Reelin is also involved in the termination of neuronal migration by degrading Dab1 via the SOCS7-Cullin5-Rbx2 system, and Reelin has been found to induce the birth-date-dependent neuronal aggregation in vivo. Based on these findings, we hypothesize that the molecular function of Reelin during neuronal migration is to control cell-adhesiveness during development by regulating the expression/activation of cell adhesion molecules.

  7. Controlling Edge Morphology in Graphene Layers Using Electron Irradiation: From Sharp Atomic Edges to Coalesced Layers Forming Loops

    SciTech Connect

    Cruz-Silva, E.; Botello-Mendez, A.R.; Barnett, Zachary M; Jia, Xiaoting; Dresselhaus, M; Terrones, H.; Terrones, M.; Sumpter, Bobby G; Meunier, Vincent

    2010-01-01

    Recent experimental reports indicate that Joule heating can atomically sharpen the edges of chemical vapor deposition grown graphitic nanoribbons. The absence or presence of loops between adjacent layers in the annealed materials is the topic of a growing debate that this Letter aims to put to rest. We offer a rationale explaining why loops do form if Joule heating is used alone, and why adjacent nanoribbon layers do not coalesce when Joule heating is applied after high-energy electrons first irradiate the sample. Our work, based on large-scale quantum molecular dynamics and electronic-transport calculations, shows that vacancies on adjacent graphene sheets, created by electron irradiation, inhibit the formation of edge loops.

  8. Layer-by-layer engineering fluorescent polyelectrolyte coated mesoporous silica nanoparticles as pH-sensitive nanocarriers for controlled release

    NASA Astrophysics Data System (ADS)

    Du, Pengcheng; Zhao, Xubo; Zeng, Jin; Guo, Jinshan; Liu, Peng

    2015-08-01

    Fluorescent core/shell composite has been fabricated by the layer-by-layer (LbL) assembly of the fluorescein isothiocyanate modified chitosan (CS-FITC) and sodium alginate (AL) onto the carboxyl modified mesoporous silica nanoparticles (MSN-COOH), followed by PEGylation. It exhibits stability in high salt-concentration media and the pH responsive fluorescent feature can be used for cell imaging. Furthermore, the modified MSN cores can enhance the DOX loading capacity and the multifunctional polyelectrolyte shell can adjust the drug release upon the media pH, showing a low leakage quantity at the neutral environment but significantly enhanced release at lower pH media mimicking the tumor environments. Therefore, the biocompatible fluorescent polyelectrolyte coated mesoporous silica nanoparticles (MSN-LBL-PEG) offer promise for tumor therapy.

  9. Nurses' knowledge and practice of vascular access infection control in haemodialysis patients in the Republic of Ireland.

    PubMed

    Higgins, Margaret; Evans, David S

    2008-06-01

    Vascular access hygiene is an integral component of haemodialysis care. Ensuring nurses possess sufficient knowledge and utilise recommended guidelines on infection control is essential for safe practice and patient safety. The study aimed to investigate nurses' knowledge and practice of vascular access infection control among adult haemodialysis patients in the Republic of Ireland. A confidential self-completion questionnaire was sent to all 190 qualified nurses employed in nine haemodialysis units in the Republic of Ireland, which assessed knowledge and behaviour in infection control. Although 92% of respondents reported that policies had been developed by their units and 47% had received infection control education in the previous year, knowledge and adherence to best practice demonstrated significant scope for improvement. The study recommended the development of standard guidelines and regular reviews and updates of policies. Systems should also be developed to ensure a high level of compliance. PMID:18498567

  10. Experimental validation of microseismic emissions from a controlled hydraulic fracture in a synthetic layered medium

    NASA Astrophysics Data System (ADS)

    Roundtree, Russell

    A controlled hydraulic fracture experiment was performed on two medium sized (11" x 11" x 15") synthetic layered blocks of low permeability, low porosity Lyons sandstone sandwiched between cement. The purpose of the research was to better understand and characterize the fracture evolution as the fracture tip impinged upon the layer boundaries between the well bonded layers. It is also one of the first documented uses of passive microseismic used in a laboratory environment to characterize hydraulic fracturing. A relatively low viscosity fluid of 1000 centipoise, compared to properly scaled previous work (Casas 2005, and Athavale 2007), was pumped at a constant rate of 10 mL/minute through a steel cased hole landed and isolated in the sandstone layer. Efforts were made to contain the hydraulic fracture within the confines of the rock specimen to retain the created hydraulic fracture geometry. Two identical samples and treatment schedules were created and differed only in the monitoring system used to characterize the microseismic activity during the fracture treatment. The first block had eight embedded P-wave transducers placed in the sandstone layer to record the passive microseismic emissions and localize the location and time of the acoustic event. The second block had six compressional wave transducers and twelve shear wave transducers embedded in the sandstone layer of the block. The intention was to record and process the seismic data using conventional P-wave to S-wave difference timing techniques well known in industry. While this goal ultimately not possible due to the geometry of the receiver placements and the limitations of the Vallene acquisition processing software, the data received and the events localized from the 18 transducer test were of much higher numbers and quality than on the eight transducer test. This experiment proved conclusively that passive seismic emission recording can yield positive results in the laboratory. Just as in the field

  11. Micro vortex generator control of axisymmetric high-speed laminar boundary layer separation

    NASA Astrophysics Data System (ADS)

    Estruch-Samper, D.; Vanstone, L.; Hillier, R.; Ganapathisubramani, B.

    2015-09-01

    Interest in the development of micro vortex generators (MVGs) to control high-speed flow separation has grown in the last decade. In contrast to conventional vortex generators, MVGs are fully submerged in the boundary layer and have the potential of inducing surface flow mixing with marginal drag penalty when suitably designed. Also, they do not result in undesired reduced mass flow such as with suction methods. The flow mechanisms at the location of MVGs are not yet fully understood, and optimal designs are difficult to establish given that both numerical predictions and experiments are particularly challenged for short element heights, yet optimal MVGs are generally expected to be at least shorter than half the local boundary layer thickness. The present work aims at investigating experimentally the fundamental flow physics concerning an individual MVG element (of `canonical' or simplified geometry) at a range of near-wall heights. A fully laminar base flow is considered so as to isolate the effect of incoming turbulence as well as the more complex physics that may occur when specific and/or multiple elements are used. Tests were performed in a gun tunnel at a freestream Mach number of 8.9 and Reynolds number of /m, and the basic test model consisted of a blunt-nosed cylinder which produced an axisymmetric laminar boundary layer with an edge Mach number of 3.4 and Reynolds number of /m at the MVG location. A laminar shock-wave/boundary layer interaction with separation was induced by a flare located further downstream on the model. Measurements consisted of time-resolved surface heat transfer obtained in the axial direction immediately downstream of the MVG and along the interaction, together with simultaneous high-speed schlieren imaging. The height () of the MVG element used in a `diamond' configuration (square planform with one vertex facing the flow) was adjusted between tests ranging from = 0.03 to 0.58, where the local undisturbed boundary layer thickness

  12. Dynamics of flow control in an emulated boundary layer-ingesting offset diffuser

    NASA Astrophysics Data System (ADS)

    Gissen, A. N.; Vukasinovic, B.; Glezer, A.

    2014-08-01

    Dynamics of flow control comprised of arrays of active (synthetic jets) and passive (vanes) control elements , and its effectiveness for suppression of total-pressure distortion is investigated experimentally in an offset diffuser, in the absence of internal flow separation. The experiments are conducted in a wind tunnel inlet model at speeds up to M = 0.55 using approach flow conditioning that mimics boundary layer ingestion on a Blended-Wing-Body platform. Time-dependent distortion of the dynamic total-pressure field at the `engine face' is measured using an array of forty total-pressure probes, and the control-induced distortion changes are analyzed using triple decomposition and proper orthogonal decomposition (POD). These data indicate that an array of the flow control small-scale synthetic jet vortices merge into two large-scale, counter-rotating streamwise vortices that exert significant changes in the flow distortion. The two most energetic POD modes appear to govern the distortion dynamics in either active or hybrid flow control approaches. Finally, it is shown that the present control approach is sufficiently robust to reduce distortion with different inlet conditions of the baseline flow.

  13. Controlled Gas Exfoliation of Boron Nitride into Few-Layered Nanosheets

    DOE PAGES

    Zhu, Wenshuai; Gao, Xiang; Li, Qian; Li, Hongping; Chao, Yanhong; Li, Meijun; Mahurin, Shannon M.; Li, Huaming; Zhu, Huiyuan; Dai, Sheng

    2016-07-22

    The controlled exfoliation of hexagonal boron nitride (h-BN) into single- or few-layered nanosheets remains a grand challenge and becomes the bottleneck to essential studies and applications of h-BN. Here, we present an efficient strategy for the scalable synthesis of few-layered h-BN nanosheets (BNNS) via a novel gas exfoliation of bulk h-BN in liquid N2 (L-N2). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h-BN and the cryogenic L-N2 gasification to exfoliate the h-BN. The produced BNNS after ten cycles (BNNS-10) consisted primarily of fewer than five atomic layers with high amore » mass yield of 16~20%. N2 sorption and desorption isotherms show that the BNNS-10 exhibited a much higher specific surface area of 278 m2/g–1 than that of bulk BN (10 m2/g–1). Through the investigation of the exfoliated intermediates combined with a theoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h-BN. Subseqently, the L-N2 penetrates into the interlayers of h-BN along the curling edge, followed by an immediate drastic gasification of L-N2, further peeling off h-BN. In conclusion, this novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications, but also can be extended to produce other layered materials with high yeilds.« less

  14. Controlled Gas Exfoliation of Boron Nitride into Few-Layered Nanosheets.

    PubMed

    Zhu, Wenshuai; Gao, Xiang; Li, Qian; Li, Hongping; Chao, Yanhong; Li, Meijun; Mahurin, Shannon M; Li, Huaming; Zhu, Huiyuan; Dai, Sheng

    2016-08-26

    The controlled exfoliation of hexagonal boron nitride (h-BN) into single- or few-layered nanosheets remains a grand challenge and becomes the bottleneck to essential studies and applications of h-BN. Here, we present an efficient strategy for the scalable synthesis of few-layered h-BN nanosheets (BNNS) using a novel gas exfoliation of bulk h-BN in liquid N2 (L-N2 ). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h-BN and the cryogenic L-N2 gasification to exfoliate the h-BN. The produced BNNS after ten cycles (BNNS-10) consisted primarily of fewer than five atomic layers with a high mass yield of 16-20 %. N2 sorption and desorption isotherms show that the BNNS-10 exhibited a much higher specific surface area of 278 m(2)  g(-1) than that of bulk BN (10 m(2)  g(-1) ). Through the investigation of the exfoliated intermediates combined with a theoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h-BN. Subseqently, the L-N2 penetrates into the interlayers of h-BN along the curling edge, followed by an immediate drastic gasification of L-N2 , further peeling off h-BN. This novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications, but also can be extended to produce other layered materials in high yields. PMID:27444210

  15. Hybrid Active/Passive Control of Sound Radiation from Panels with Constrained Layer Damping and Model Predictive Feedback Control

    NASA Technical Reports Server (NTRS)

    Cabell, Randolph H.; Gibbs, Gary P.

    2000-01-01

    There has been considerable interest over the past several years in applying feedback control methods to problems of structural acoustics. One problem of particular interest is the control of sound radiation from aircraft panels excited on one side by a turbulent boundary layer (TBL). TBL excitation appears as many uncorrelated sources acting on the panel, which makes it difficult to find a single reference signal that is coherent with the excitation. Feedback methods have no need for a reference signal, and are thus suited to this problem. Some important considerations for the structural acoustics problem include the fact that the required controller bandwidth can easily extend to several hundred Hertz, so a digital controller would have to operate at a few kilohertz. In addition, aircraft panel structures have a reasonably high modal density over this frequency range. A model based controller must therefore handle the modally dense system, or have some way to reduce the bandwidth of the problem. Further complicating the problem is the fact that the stiffness and dynamic properties of an aircraft panel can vary considerably during flight due to altitude changes resulting in significant resonant frequency shifts. These considerations make the tradeoff between robustness to changes in the system being controlled and controller performance especially important. Recent papers concerning the design and implementation of robust controllers for structural acoustic problems highlight the need to consider both performance and robustness when designing the controller. While robust control methods such as H1 can be used to balance performance and robustness, their implementation is not easy and requires assumptions about the types of uncertainties in the plant being controlled. Achieving a useful controller design may require many tradeoff studies of different types of parametric uncertainties in the system. Another approach to achieving robustness to plant changes is to

  16. Parametric investigation of boundary layer control using triangular micro vortex generators

    NASA Astrophysics Data System (ADS)

    Bagheri, Milad; Muslmani, Motassem Al; Masood, Asad; Khosravi, Mahmood; Atef Mahmoud, Mohamed; Cardoz, Aniket; Akkuwari, Abdulrahman; Alanezi, Yusuf; Kim, Young

    2014-03-01

    Improving the aerodynamic performance of an airfoil is one of the primary interests of the Aerodynamicists. Such performance improvement can be achieved using passive or active flow control devices. One of such passive devices having a compact size along with an effective performance is the Micro Vortex Generators (MVGs). A special type of MVGs, which has been recently introduced in the aerospace industry, is "Triangular Shape" MVGs and its impact on aerodynamic characteristics is the main interest of this study. This study will compare the effects of various configurations through which delay of the flow separation using boundary layer control will be analysed by experimental and theoretical approach. The experimental investigations have been conducted using subsonic wind tunnel and the theoretical analysis using ANSYS® 13.0 FLUENT of which the final results are compared with each other.

  17. Nucleo-olivary inhibition balances the interaction between the reactive and adaptive layers in motor control.

    PubMed

    Herreros, Ivan; Verschure, Paul F M J

    2013-11-01

    In the acquisition of adaptive motor reflexes to aversive stimuli, the cerebellar output fulfills a double purpose: it controls a motor response and it relays a sensory prediction. However, the question of how these two apparently incompatible goals might be achieved by the same cerebellar area remains open. Here we propose a solution where the inhibition of the Inferior Olive (IO) by the cerebellar Deep Nuclei (DN) translates the motor command signal into a sensory prediction allowing a single cerebellar area to simultaneously tackle both aspects of the problem: execution and prediction. We demonstrate that having a graded error signal, the gain of the Nucleo-Olivary Inhibition (NOI) balances the generation of the response between the cerebellar and the reflexive controllers or, in other words, between the adaptive and the reactive layers of behavior. Moreover, we show that the resulting system is fully autonomous and can either acquire or erase adaptive responses according to their utility.

  18. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

  19. FMO-based H.264 frame layer rate control for low bit rate video transmission

    NASA Astrophysics Data System (ADS)

    Cajote, Rhandley D.; Aramvith, Supavadee; Miyanaga, Yoshikazu

    2011-12-01

    The use of flexible macroblock ordering (FMO) in H.264/AVC improves error resiliency at the expense of reduced coding efficiency with added overhead bits for slice headers and signalling. The trade-off is most severe at low bit rates, where header bits occupy a significant portion of the total bit budget. To better manage the rate and improve coding efficiency, we propose enhancements to the H.264/AVC frame layer rate control, which take into consideration the effects of using FMO for video transmission. In this article, we propose a new header bits model, an enhanced frame complexity measure, a bit allocation and a quantization parameter adjustment scheme. Simulation results show that the proposed improvements achieve better visual quality compared with the JM 9.2 frame layer rate control with FMO enabled using a different number of slice groups. Using FMO as an error resilient tool with better rate management is suitable in applications that have limited bandwidth and in error prone environments such as video transmission for mobile terminals.

  20. Wind-Tunnel Tests on Airfoil Boundary Layer Control Using a Backward-Opening Slot

    NASA Technical Reports Server (NTRS)

    Bamber, Millard J

    1932-01-01

    This report presents the results of an investigation to determine the effect of boundary layer control on the lift and drag of an airfoil. Boundary layer control was accomplished by means of a backward-opening slot in the upper surface of the hollow airfoil. Air was caused to flow through this slot by a pressure which was maintained inside the airfoil by a blower. Various slot locations, slot openings, and wing pressures were used. The tests were conducted in the 5-foot atmospheric wind tunnel of the Langley Memorial Aeronautical Laboratory. Under the test conditions, the maximum lift coefficient was increased about 96 per cent for one slot arrangement, and the minimum drag coefficient was decreased about 27 per cent for another, both being compared with the results obtained with the unslotted airfoil. It is believed from this investigation that the above effects may be increased by the use of larger slot openings, better slot locations, multiple slots, improved airfoil profiles, and trailing edge flaps.