Implementation of a Cross-Layer Sensing Medium-Access Control Scheme.
Su, Yishan; Fu, Xiaomei; Han, Guangyao; Xu, Naishen; Jin, Zhigang
2017-04-10
In this paper, compressed sensing (CS) theory is utilized in a medium-access control (MAC) scheme for wireless sensor networks (WSNs). We propose a new, cross-layer compressed sensing medium-access control (CL CS-MAC) scheme, combining the physical layer and data link layer, where the wireless transmission in physical layer is considered as a compress process of requested packets in a data link layer according to compressed sensing (CS) theory. We first introduced using compressive complex requests to identify the exact active sensor nodes, which makes the scheme more efficient. Moreover, because the reconstruction process is executed in a complex field of a physical layer, where no bit and frame synchronizations are needed, the asynchronous and random requests scheme can be implemented without synchronization payload. We set up a testbed based on software-defined radio (SDR) to implement the proposed CL CS-MAC scheme practically and to demonstrate the validation. For large-scale WSNs, the simulation results show that the proposed CL CS-MAC scheme provides higher throughput and robustness than the carrier sense multiple access (CSMA) and compressed sensing medium-access control (CS-MAC) schemes.
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.
Spatiotemporal Access Model Based on Reputation for the Sensing Layer of the IoT
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
Spatiotemporal access model based on reputation for the sensing layer of the IoT.
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.
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.
Liu, Xuemei; Ge, Baofeng
2012-04-01
This paper proposes a media access control (MAC) layer design for wireless body area network (WBAN) systems. WBAN is a technology that targets for wireless networking of wearable and implantable body sensors which monitor vital body signs, such as heart-rate, body temperature, blood pressure, etc. It has been receiving attentions from international organizations, e. g. the Institute of Electrical and Electronics Engineers (IEEE), due to its capability of providing efficient healthcare services and clinical management. This paper reviews the standardization procedure of WBAN and summarizes the challenge of the MAC layer design. It also discusses the methods of improving power consumption performance, which is one of the major issues of WBAN systems.
Formalization of the Access Control on ARM-Android Platform with the B Method
NASA Astrophysics Data System (ADS)
Ren, Lu; Wang, Wei; Zhu, Xiaodong; Man, Yujia; Yin, Qing
2018-01-01
ARM-Android is a widespread mobile platform with multi-layer access control mechanisms, security-critical in the system. Many access control vulnerabilities still exist due to the course-grained policy and numerous engineering defects, which have been widely studied. However, few researches focus on the mechanism formalization, including the Android permission framework, kernel process management and hardware isolation. This paper first develops a comprehensive formal access control model on the ARM-Android platform using the B method, from the Android middleware to hardware layer. All the model specifications are type checked and proved to be well-defined, with 75%of proof obligations demonstrated automatically. The results show that the proposed B model is feasible to specify and verify access control schemes in the ARM-Android system, and capable of implementing a practical control module.
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
Gray, Lucas T; Yao, Zizhen; Nguyen, Thuc Nghi; Kim, Tae Kyung; Zeng, Hongkui; Tasic, Bosiljka
2017-01-01
Mammalian cortex is a laminar structure, with each layer composed of a characteristic set of cell types with different morphological, electrophysiological, and connectional properties. Here, we define chromatin accessibility landscapes of major, layer-specific excitatory classes of neurons, and compare them to each other and to inhibitory cortical neurons using the Assay for Transposase-Accessible Chromatin with high-throughput sequencing (ATAC-seq). We identify a large number of layer-specific accessible sites, and significant association with genes that are expressed in specific cortical layers. Integration of these data with layer-specific transcriptomic profiles and transcription factor binding motifs enabled us to construct a regulatory network revealing potential key layer-specific regulators, including Cux1/2, Foxp2, Nfia, Pou3f2, and Rorb. This dataset is a valuable resource for identifying candidate layer-specific cis-regulatory elements in adult mouse cortex. DOI: http://dx.doi.org/10.7554/eLife.21883.001 PMID:28112643
Sefuba, Maria; Walingo, Tom; Takawira, Fambirai
2015-09-18
This paper presents an Energy Efficient Medium Access Control (MAC) protocol for clustered wireless sensor networks that aims to improve energy efficiency and delay performance. The proposed protocol employs an adaptive cross-layer intra-cluster scheduling and an inter-cluster relay selection diversity. The scheduling is based on available data packets and remaining energy level of the source node (SN). This helps to minimize idle listening on nodes without data to transmit as well as reducing control packet overhead. The relay selection diversity is carried out between clusters, by the cluster head (CH), and the base station (BS). The diversity helps to improve network reliability and prolong the network lifetime. Relay selection is determined based on the communication distance, the remaining energy and the channel quality indicator (CQI) for the relay cluster head (RCH). An analytical framework for energy consumption and transmission delay for the proposed MAC protocol is presented in this work. The performance of the proposed MAC protocol is evaluated based on transmission delay, energy consumption, and network lifetime. The results obtained indicate that the proposed MAC protocol provides improved performance than traditional cluster based MAC protocols.
Sefuba, Maria; Walingo, Tom; Takawira, Fambirai
2015-01-01
This paper presents an Energy Efficient Medium Access Control (MAC) protocol for clustered wireless sensor networks that aims to improve energy efficiency and delay performance. The proposed protocol employs an adaptive cross-layer intra-cluster scheduling and an inter-cluster relay selection diversity. The scheduling is based on available data packets and remaining energy level of the source node (SN). This helps to minimize idle listening on nodes without data to transmit as well as reducing control packet overhead. The relay selection diversity is carried out between clusters, by the cluster head (CH), and the base station (BS). The diversity helps to improve network reliability and prolong the network lifetime. Relay selection is determined based on the communication distance, the remaining energy and the channel quality indicator (CQI) for the relay cluster head (RCH). An analytical framework for energy consumption and transmission delay for the proposed MAC protocol is presented in this work. The performance of the proposed MAC protocol is evaluated based on transmission delay, energy consumption, and network lifetime. The results obtained indicate that the proposed MAC protocol provides improved performance than traditional cluster based MAC protocols. PMID:26393608
AEROSAT Access Control Summary
DOT National Transportation Integrated Search
1976-10-01
The report consists of three basic sections. Section 2 is a discussion of the communications concepts germane to AEROSAT access control. It defines and reviews the principles of multiplexing, multiple access, demand access, and access control and rel...
Aerosat Access Control Summary
DOT National Transportation Integrated Search
1976-10-01
The report consists of three basic sections. Section 2 is a discussion of the communications concepts germane to AEROSAT access control. It defines and reviews the principles of multiplexing, multiple access, demand access, and access control and rel...
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.
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…
Tunneling and Origin of Large Access Resistance in Layered-Crystal Organic Transistors
NASA Astrophysics Data System (ADS)
Hamai, Takamasa; Arai, Shunto; Minemawari, Hiromi; Inoue, Satoru; Kumai, Reiji; Hasegawa, Tatsuo
2017-11-01
Layered crystallinity of organic semiconductors is crucial to obtaining high-performance organic thin-film transistors (OTFTs), as it allows both smooth-channel-gate-insulator interface formation and efficient two-dimensional carrier transport along the interface. However, the role of vertical transport across the crystalline molecular layers in device operations has not been a crucial subject so far. Here, we show that the interlayer carrier transport causes unusual nonlinear current-voltage characteristics and enormous access resistance in extremely high-quality single-crystal OTFTs based on 2-decyl-7-phenyl[1]-benzothieno[3 ,2 -b ][1]benzothiophene (Ph -BTBT -C10 ) that involve inherent multiple semiconducting π -conjugated layers interposed, respectively, by electrically inert alkyl-chain layers. The output characteristics present layer-number (n )-dependent nonlinearity that becomes more evident at larger n (1 ≤n ≤15 ), demonstrating tunneling across multiple alkyl-chain layers. The n -dependent device mobility and four-probe measurements reveal that the alkyl-chain layers generate a large access resistance that suppresses the device mobility from the intrinsic value of about 20 cm2 V-1 s-1 . Our findings clarify the reason why device characteristics are distributed in single-crystal OTFTs.
Analysis of physical layer performance of hybrid optical-wireless access network
NASA Astrophysics Data System (ADS)
Shaddad, R. Q.; Mohammad, A. B.; Al-hetar, A. M.
2011-09-01
The hybrid optical-wireless access network (HOWAN) is a favorable architecture for next generation access network. It is an optimal combination of an optical backhaul and a wireless front-end for an efficient access network. In this paper, the HOWAN architecture is designed based on a wavelengths division multiplexing/time division multiplexing passive optical network (WDM/TDM PON) at the optical backhaul and a wireless fidelity (WiFi) technology at the wireless front-end. The HOWAN is proposed that can provide blanket coverage of broadband and flexible connection for end-users. Most of the existing works, based on performance evaluation are concerned on network layer aspects. This paper reports physical layer performance in terms of the bit error rate (BER), eye diagram, and signal-to-noise ratio (SNR) of the communication system. It accommodates 8 wavelength channels with 32 optical network unit/wireless access points (ONU/APs). It is demonstrated that downstream and upstream of 2 Gb/s can be achieved by optical backhaul for each wavelength channel along optical fiber length of 20 km and a data rate of 54 Mb/s per ONU/AP along a 50 m outdoor wireless link.
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…
Efficient Access Control in Multimedia Social Networks
NASA Astrophysics Data System (ADS)
Sachan, Amit; Emmanuel, Sabu
Multimedia social networks (MMSNs) have provided a convenient way to share multimedia contents such as images, videos, blogs, etc. Contents shared by a person can be easily accessed by anybody else over the Internet. However, due to various privacy, security, and legal concerns people often want to selectively share the contents only with their friends, family, colleagues, etc. Access control mechanisms play an important role in this situation. With access control mechanisms one can decide the persons who can access a shared content and who cannot. But continuously growing content uploads and accesses, fine grained access control requirements (e.g. different access control parameters for different parts in a picture), and specific access control requirements for multimedia contents can make the time complexity of access control to be very large. So, it is important to study an efficient access control mechanism suitable for MMSNs. In this chapter we present an efficient bit-vector transform based access control mechanism for MMSNs. The proposed approach is also compatible with other requirements of MMSNs, such as access rights modification, content deletion, etc. Mathematical analysis and experimental results show the effectiveness and efficiency of our proposed approach.
An extended smart utilization medium access control (ESU-MAC) protocol for ad hoc wireless systems
NASA Astrophysics Data System (ADS)
Vashishtha, Jyoti; Sinha, Aakash
2006-05-01
The demand for spontaneous setup of a wireless communication system has increased in recent years for areas like battlefield, disaster relief operations etc., where a pre-deployment of network infrastructure is difficult or unavailable. A mobile ad-hoc network (MANET) is a promising solution, but poses a lot of challenges for all the design layers, specifically medium access control (MAC) layer. Recent existing works have used the concepts of multi-channel and power control in designing MAC layer protocols. SU-MAC developed by the same authors, efficiently uses the 'available' data and control bandwidth to send control information and results in increased throughput via decreasing contention on the control channel. However, SU-MAC protocol was limited for static ad-hoc network and also faced the busy-receiver node problem. We present the Extended SU-MAC (ESU-MAC) protocol which works mobile nodes. Also, we significantly improve the scheme of control information exchange in ESU-MAC to overcome the busy-receiver node problem and thus, further avoid the blockage of control channel for longer periods of time. A power control scheme is used as before to reduce interference and to effectively re-use the available bandwidth. Simulation results show that ESU-MAC protocol is promising for mobile, ad-hoc network in terms of reduced contention at the control channel and improved throughput because of channel re-use. Results show a considerable increase in throughput compared to SU-MAC which could be attributed to increased accessibility of control channel and improved utilization of data channels due to superior control information exchange scheme.
A service-oriented data access control model
NASA Astrophysics Data System (ADS)
Meng, Wei; Li, Fengmin; Pan, Juchen; Song, Song; Bian, Jiali
2017-01-01
The development of mobile computing, cloud computing and distributed computing meets the growing individual service needs. Facing with complex application system, it's an urgent problem to ensure real-time, dynamic, and fine-grained data access control. By analyzing common data access control models, on the basis of mandatory access control model, the paper proposes a service-oriented access control model. By regarding system services as subject and data of databases as object, the model defines access levels and access identification of subject and object, and ensures system services securely to access databases.
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…
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... Requirements for Irradiators § 36.23 Access control. (a) Each entrance to a radiation room at a panoramic... radiation room at a panoramic irradiator must have an independent backup access control to detect personnel...
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... Requirements for Irradiators § 36.23 Access control. (a) Each entrance to a radiation room at a panoramic... radiation room at a panoramic irradiator must have an independent backup access control to detect personnel...
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... Requirements for Irradiators § 36.23 Access control. (a) Each entrance to a radiation room at a panoramic... radiation room at a panoramic irradiator must have an independent backup access control to detect personnel...
DOT National Transportation Integrated Search
1974-06-01
The report presents a summary of a study conducted for the Transportation Systems Center of promising access control techniques which are applicable to an aeronautical satellite system. Several frequency division multiple access (FDMA) and time divis...
Access Control in Location-Based Services
NASA Astrophysics Data System (ADS)
Ardagna, Claudio A.; Cremonini, Marco; de Capitani di Vimercati, Sabrina; Samarati, Pierangela
Recent enhancements in location technologies reliability and precision are fostering the development of a new wave of applications that make use of the location information of users. Such applications introduces new aspects of access control which should be addressed. On the one side, precise location information may play an important role and can be used to develop Location-based Access Control (LBAC) systems that integrate traditional access control mechanisms with conditions based on the physical position of users. On the other side, location information of users can be considered sensitive and access control solutions should be developed to protect it against unauthorized accesses and disclosures. In this chapter, we address these two aspects related to the use and protection of location information, discussing existing solutions, open issues, and some research directions.
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.
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 control...
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 control...
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 control...
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 control...
Linear Time Algorithms to Restrict Insider Access using Multi-Policy Access Control Systems
Mell, Peter; Shook, James; Harang, Richard; Gavrila, Serban
2017-01-01
An important way to limit malicious insiders from distributing sensitive information is to as tightly as possible limit their access to information. This has always been the goal of access control mechanisms, but individual approaches have been shown to be inadequate. Ensemble approaches of multiple methods instantiated simultaneously have been shown to more tightly restrict access, but approaches to do so have had limited scalability (resulting in exponential calculations in some cases). In this work, we take the Next Generation Access Control (NGAC) approach standardized by the American National Standards Institute (ANSI) and demonstrate its scalability. The existing publicly available reference implementations all use cubic algorithms and thus NGAC was widely viewed as not scalable. The primary NGAC reference implementation took, for example, several minutes to simply display the set of files accessible to a user on a moderately sized system. In our approach, we take these cubic algorithms and make them linear. We do this by reformulating the set theoretic approach of the NGAC standard into a graph theoretic approach and then apply standard graph algorithms. We thus can answer important access control decision questions (e.g., which files are available to a user and which users can access a file) using linear time graph algorithms. We also provide a default linear time mechanism to visualize and review user access rights for an ensemble of access control mechanisms. Our visualization appears to be a simple file directory hierarchy but in reality is an automatically generated structure abstracted from the underlying access control graph that works with any set of simultaneously instantiated access control policies. It also provide an implicit mechanism for symbolic linking that provides a powerful access capability. Our work thus provides the first efficient implementation of NGAC while enabling user privilege review through a novel visualization approach. This
CAS. Controlled Access Security
DOE Office of Scientific and Technical Information (OSTI.GOV)
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.
An Attribute Based Access Control Framework for Healthcare System
NASA Astrophysics Data System (ADS)
Afshar, Majid; Samet, Saeed; Hu, Ting
2018-01-01
Nowadays, access control is an indispensable part of the Personal Health Record and supplies for its confidentiality by enforcing policies and rules to ensure that only authorized users gain access to requested resources in the system. In other words, the access control means protecting patient privacy in healthcare systems. Attribute-Based Access Control (ABAC) is a new access control model that can be used instead of other traditional types of access control such as Discretionary Access Control, Mandatory Access Control, and Role-Based Access Control. During last five years ABAC has shown some applications in both recent academic fields and industry purposes. ABAC by using user’s attributes and resources, makes a decision according to an access request. In this paper, we propose an ABAC framework for healthcare system. We use the engine of ABAC for rendering and enforcing healthcare policies. Moreover, we handle emergency situations in this framework.
Access control for electronic patient records.
Glagola, M J
1998-01-01
The transition from hardcopy records to electronic records is in the forefront for healthcare today. For healthcare facilities, a major issue is determining who can access patients' medical information and how access to this information can be controlled. There are three components to access control: identification, authentication and authorization. Checking proof of identity is a means of authenticating someone--through a driver's license, passport or their fingerprints. Similar processes are needed in a computer environment, through the use of passwords, one-time passwords or smartcards, encryption and kerberos, and call-back procedures. New in the area of access control are biometric devices, which are hardware/software combinations that digitize a physical characteristic and compare the sample with previously stored samples. Fingerprints, voiceprints and facial features are examples. Their cost is currently prohibitive, but in time, they may become more common. Digital certificates and certification authorities are other means used to authenticate identify. When a system challenges a user's identity at log on, the user provides a certification that tells the system to go to the issuing certification authority and find proof the user's claim is valid. Low-level certifications offer little value for sensitive data, but high-level certification is now being introduced. It requires more specific, detailed information on the applicant. Authorization, the final component of access control, establishes what a specific user can and cannot access. To have effective access control, transaction logging and system monitoring are needed to ensure the various techniques are being used and performing properly.
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.
Boundary layer control for airships
NASA Technical Reports Server (NTRS)
Pake, F. A.; Pipitone, S. J.
1975-01-01
An investigation is summarized of the aerodynamic principle of boundary layer control for nonrigid LTA craft. The project included a wind tunnel test on a BLC body of revolution at zero angle of attack. Theoretical analysis is shown to be in excellent agreement with the test data. Methods are evolved for predicting the boundary layer development on a body of revolution and the suction pumping and propulsive power requirements. These methods are used to predict the performance characteristics of a full-scale airship. The analysis indicates that propulsive power reductions of 15 to 25 percent and endurance improvements of 20 to 40 percent may be realized in employing boundary-layer control to nonrigid airships.
Separation control in a hypersonic shock wave / turbulent boundary-layer interaction
NASA Astrophysics Data System (ADS)
Schreyer, Anne-Marie; Bermejo-Moreno, Ivan; Kim, Jeonglae; Urzay, Javier
2016-11-01
Hypersonic vehicles play a key role for affordable access to space. The associated flow fields are strongly affected by shock wave/turbulent boundary-layer interactions, and the inherent separation causes flow distortion and low-frequency unsteadiness. Microramp sub-boundary layer vortex generators are a promising means to control separation and diminish associated detrimental effects. We investigate the effect of a microramp on the low-frequency unsteadiness in a fully separated interaction. A large eddy simulation of a 33 ∘ -compression-ramp interaction was performed for an inflow Mach number of 7.2 and a Reynolds number based on momentum thickness of Reθ = 3500 , matching the experiment of Schreyer et al. (2011). For the control case, we introduced a counter-rotating vortex pair, as induced by a single microramp, into the boundary layer through the inflow conditions. We applied a dynamic mode decomposition (DMD) on both cases to identify coherent structures that are responsible for the dynamic behavior. Based on the DMD, we discuss the reduction of the separation zone and the stabilization of the shock motion achieved by the microramp, and contribute to the description of the governing mechanisms. Pursued during the 2016 CTR Summer Program at Stanford University.
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.
Logical Access Control Mechanisms in Computer Systems.
ERIC Educational Resources Information Center
Hsiao, David K.
The subject of access control mechanisms in computer systems is concerned with effective means to protect the anonymity of private information on the one hand, and to regulate the access to shareable information on the other hand. Effective means for access control may be considered on three levels: memory, process and logical. This report is a…
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.
Access control mechanism of wireless gateway based on open flow
NASA Astrophysics Data System (ADS)
Peng, Rong; Ding, Lei
2017-08-01
In order to realize the access control of wireless gateway and improve the access control of wireless gateway devices, an access control mechanism of SDN architecture which is based on Open vSwitch is proposed. The mechanism utilizes the features of the controller--centralized control and programmable. Controller send access control flow table based on the business logic. Open vSwitch helps achieve a specific access control strategy based on the flow table.
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.
A Scalable Data Access Layer to Manage Structured Heterogeneous Biomedical Data.
Delussu, Giovanni; Lianas, Luca; Frexia, Francesca; Zanetti, Gianluigi
2016-01-01
This work presents a scalable data access layer, called PyEHR, designed to support the implementation of data management systems for secondary use of structured heterogeneous biomedical and clinical data. PyEHR adopts the openEHR's formalisms to guarantee the decoupling of data descriptions from implementation details and exploits structure indexing to accelerate searches. Data persistence is guaranteed by a driver layer with a common driver interface. Interfaces for two NoSQL Database Management Systems are already implemented: MongoDB and Elasticsearch. We evaluated the scalability of PyEHR experimentally through two types of tests, called "Constant Load" and "Constant Number of Records", with queries of increasing complexity on synthetic datasets of ten million records each, containing very complex openEHR archetype structures, distributed on up to ten computing nodes.
A Scalable Data Access Layer to Manage Structured Heterogeneous Biomedical Data
Lianas, Luca; Frexia, Francesca; Zanetti, Gianluigi
2016-01-01
This work presents a scalable data access layer, called PyEHR, designed to support the implementation of data management systems for secondary use of structured heterogeneous biomedical and clinical data. PyEHR adopts the openEHR’s formalisms to guarantee the decoupling of data descriptions from implementation details and exploits structure indexing to accelerate searches. Data persistence is guaranteed by a driver layer with a common driver interface. Interfaces for two NoSQL Database Management Systems are already implemented: MongoDB and Elasticsearch. We evaluated the scalability of PyEHR experimentally through two types of tests, called “Constant Load” and “Constant Number of Records”, with queries of increasing complexity on synthetic datasets of ten million records each, containing very complex openEHR archetype structures, distributed on up to ten computing nodes. PMID:27936191
Layer-by-layer-based silica encapsulation of individual yeast with thickness control.
Lee, Hojae; Hong, Daewha; Choi, Ji Yu; Kim, Ji Yup; Lee, Sang Hee; Kim, Ho Min; Yang, Sung Ho; Choi, Insung S
2015-01-01
In the area of cell-surface engineering with nanomaterials, the metabolic and functional activities of the encapsulated cells are manipulated and controlled by various parameters of the artificial shells that encase the cells, such as stiffness and elasticity, thickness, and porosity. The mechanical durability and physicochemical stability of inorganic shells prove superior to layer-by-layer-based organic shells with regard to cytoprotection, but it has been difficult to vary the parameters of inorganic shells including their thickness. In this work, we combine the layer-by-layer technique with a process of bioinspired silicification to control the thickness of the silica shells that encapsulate yeast Saccharomyces cerevisiae cells individually, and investigate the thickness-dependent microbial growth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Role-based access control permissions
Staggs, Kevin P.; Markham, Thomas R.; Hull Roskos, Julie J.; Chernoguzov, Alexander
2017-04-25
Devices, systems, and methods for role-based access control permissions are disclosed. One method includes a policy decision point that receives up-to-date security context information from one or more outside sources to determine whether to grant access for a data client to a portion of the system and creates an access vector including the determination; receiving, via a policy agent, a request by the data client for access to the portion of the computing system by the data client, wherein the policy agent checks to ensure there is a session established with communications and user/application enforcement points; receiving, via communications policy enforcement point, the request from the policy agent, wherein the communications policy enforcement point determines whether the data client is an authorized node, based upon the access vector received from the policy decision point; and receiving, via the user/application policy enforcement point, the request from the communications policy enforcement point.
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.
Access control based on attribute certificates for medical intranet applications.
Mavridis, I; Georgiadis, C; Pangalos, G; Khair, M
2001-01-01
Clinical information systems frequently use intranet and Internet technologies. However these technologies have emphasized sharing and not security, despite the sensitive and private nature of much health information. Digital certificates (electronic documents which recognize an entity or its attributes) can be used to control access in clinical intranet applications. To outline the need for access control in distributed clinical database systems, to describe the use of digital certificates and security policies, and to propose the architecture for a system using digital certificates, cryptography and security policy to control access to clinical intranet applications. We have previously developed a security policy, DIMEDAC (Distributed Medical Database Access Control), which is compatible with emerging public key and privilege management infrastructure. In our implementation approach we propose the use of digital certificates, to be used in conjunction with DIMEDAC. Our proposed access control system consists of two phases: the ways users gain their security credentials; and how these credentials are used to access medical data. Three types of digital certificates are used: identity certificates for authentication; attribute certificates for authorization; and access-rule certificates for propagation of access control policy. Once a user is identified and authenticated, subsequent access decisions are based on a combination of identity and attribute certificates, with access-rule certificates providing the policy framework. Access control in clinical intranet applications can be successfully and securely managed through the use of digital certificates and the DIMEDAC security policy.
Access Control based on Attribute Certificates for Medical Intranet Applications
Georgiadis, Christos; Pangalos, George; Khair, Marie
2001-01-01
Background Clinical information systems frequently use intranet and Internet technologies. However these technologies have emphasized sharing and not security, despite the sensitive and private nature of much health information. Digital certificates (electronic documents which recognize an entity or its attributes) can be used to control access in clinical intranet applications. Objectives To outline the need for access control in distributed clinical database systems, to describe the use of digital certificates and security policies, and to propose the architecture for a system using digital certificates, cryptography and security policy to control access to clinical intranet applications. Methods We have previously developed a security policy, DIMEDAC (Distributed Medical Database Access Control), which is compatible with emerging public key and privilege management infrastructure. In our implementation approach we propose the use of digital certificates, to be used in conjunction with DIMEDAC. Results Our proposed access control system consists of two phases: the ways users gain their security credentials; and how these credentials are used to access medical data. Three types of digital certificates are used: identity certificates for authentication; attribute certificates for authorization; and access-rule certificates for propagation of access control policy. Once a user is identified and authenticated, subsequent access decisions are based on a combination of identity and attribute certificates, with access-rule certificates providing the policy framework. Conclusions Access control in clinical intranet applications can be successfully and securely managed through the use of digital certificates and the DIMEDAC security policy. PMID:11720951
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.
Review of SDDOT's highway access control process
DOT National Transportation Integrated Search
2000-02-01
This report presents the results and recommendations of a review of the South Dakota Department of Transportation's (SDDOT's) highway access control process. This document presents recommendations that improve South Dakota's access policy. The docume...
Typing for Conflict Detection in Access Control Policies
NASA Astrophysics Data System (ADS)
Adi, Kamel; Bouzida, Yacine; Hattak, Ikhlass; Logrippo, Luigi; Mankovskii, Serge
In this paper we present an access control model that considers both abstract and concrete access control policies specifications. Permissions and prohibitions are expressed within this model with contextual conditions. This situation may lead to conflicts. We propose a type system that is applied to the different rules in order to check for inconsistencies. If a resource is well typed, it is guaranteed that access rules to the resource contain no conflicts.
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)
Layer Control of WSe2 via Selective Surface Layer Oxidation.
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.
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…
Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems
Xia, Feng; Ma, Longhua; Peng, Chen; Sun, Youxian; Dong, Jinxiang
2008-01-01
There is a trend towards using wireless technologies in networked control systems. However, the adverse properties of the radio channels make it difficult to design and implement control systems in wireless environments. To attack the uncertainty in available communication resources in wireless control systems closed over WLAN, a cross-layer adaptive feedback scheduling (CLAFS) scheme is developed, which takes advantage of the co-design of control and wireless communications. By exploiting cross-layer design, CLAFS adjusts the sampling periods of control systems at the application layer based on information about deadline miss ratio and transmission rate from the physical layer. Within the framework of feedback scheduling, the control performance is maximized through controlling the deadline miss ratio. Key design parameters of the feedback scheduler are adapted to dynamic changes in the channel condition. An event-driven invocation mechanism for the feedback scheduler is also developed. Simulation results show that the proposed approach is efficient in dealing with channel capacity variations and noise interference, thus providing an enabling technology for control over WLAN. PMID:27879934
Towards an Approach of Semantic Access Control for Cloud Computing
NASA Astrophysics Data System (ADS)
Hu, Luokai; Ying, Shi; Jia, Xiangyang; Zhao, Kai
With the development of cloud computing, the mutual understandability among distributed Access Control Policies (ACPs) has become an important issue in the security field of cloud computing. Semantic Web technology provides the solution to semantic interoperability of heterogeneous applications. In this paper, we analysis existing access control methods and present a new Semantic Access Control Policy Language (SACPL) for describing ACPs in cloud computing environment. Access Control Oriented Ontology System (ACOOS) is designed as the semantic basis of SACPL. Ontology-based SACPL language can effectively solve the interoperability issue of distributed ACPs. This study enriches the research that the semantic web technology is applied in the field of security, and provides a new way of thinking of access control in cloud computing.
49 CFR 1542.207 - Access control systems.
Code of Federal Regulations, 2010 CFR
2010-10-01
... Transportation Other Regulations Relating to Transportation (Continued) TRANSPORTATION SECURITY ADMINISTRATION, DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control... original access medium, if the airport operator follows measures and procedures in the security program...
49 CFR 1542.207 - Access control systems.
Code of Federal Regulations, 2013 CFR
2013-10-01
... Transportation Other Regulations Relating to Transportation (Continued) TRANSPORTATION SECURITY ADMINISTRATION, DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control... original access medium, if the airport operator follows measures and procedures in the security program...
49 CFR 1542.207 - Access control systems.
Code of Federal Regulations, 2014 CFR
2014-10-01
... Transportation Other Regulations Relating to Transportation (Continued) TRANSPORTATION SECURITY ADMINISTRATION, DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control... original access medium, if the airport operator follows measures and procedures in the security program...
49 CFR 1542.207 - Access control systems.
Code of Federal Regulations, 2011 CFR
2011-10-01
... Transportation Other Regulations Relating to Transportation (Continued) TRANSPORTATION SECURITY ADMINISTRATION, DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control... original access medium, if the airport operator follows measures and procedures in the security program...
49 CFR 1542.207 - Access control systems.
Code of Federal Regulations, 2012 CFR
2012-10-01
... Transportation Other Regulations Relating to Transportation (Continued) TRANSPORTATION SECURITY ADMINISTRATION, DEPARTMENT OF HOMELAND SECURITY CIVIL AVIATION SECURITY AIRPORT SECURITY Operations § 1542.207 Access control... original access medium, if the airport operator follows measures and procedures in the security program...
Context-aware access control for pervasive access to process-based healthcare systems.
Koufi, Vassiliki; Vassilacopoulos, George
2008-01-01
Healthcare is an increasingly collaborative enterprise involving a broad range of healthcare services provided by many individuals and organizations. Grid technology has been widely recognized as a means for integrating disparate computing resources in the healthcare field. Moreover, Grid portal applications can be developed on a wireless and mobile infrastructure to execute healthcare processes which, in turn, can provide remote access to Grid database services. Such an environment provides ubiquitous and pervasive access to integrated healthcare services at the point of care, thus improving healthcare quality. In such environments, the ability to provide an effective access control mechanism that meets the requirement of the least privilege principle is essential. Adherence to the least privilege principle requires continuous adjustments of user permissions in order to adapt to the current situation. This paper presents a context-aware access control mechanism for HDGPortal, a Grid portal application which provides access to workflow-based healthcare processes using wireless Personal Digital Assistants. The proposed mechanism builds upon and enhances security mechanisms provided by the Grid Security Infrastructure. It provides tight, just-in-time permissions so that authorized users get access to specific objects according to the current context. These permissions are subject to continuous adjustments triggered by the changing context. Thus, the risk of compromising information integrity during task executions is reduced.
Bristled shark skin: a microgeometry for boundary layer control?
Lang, A W; Motta, P; Hidalgo, P; Westcott, M
2008-12-01
There exists evidence that some fast-swimming shark species may have the ability to bristle their scales during fast swimming. Experimental work using a water tunnel facility has been performed to investigate the flow field over and within a bristled shark skin model submerged within a boundary layer to deduce the possible boundary layer control mechanisms being used by these fast-swimming sharks. Fluorescent dye flow visualization provides evidence of the formation of embedded cavity vortices within the scales. Digital particle image velocimetry (DPIV) data, used to evaluate the cavity vortex formation and boundary layer characteristics close to the surface, indicate increased momentum in the slip layer forming above the scales. This increase in flow velocity close to the shark's skin is indicative of boundary layer control mechanisms leading to separation control and possibly transition delay for the bristled shark skin microgeometry.
Controlling the Growth of Staphylococcus epidermidis by Layer-By-Layer Encapsulation.
Jonas, Alain M; Glinel, Karine; Behrens, Adam; Anselmo, Aaron C; Langer, Robert S; Jaklenec, Ana
2018-05-16
Commensal skin bacteria such as Staphylococcus epidermidis are currently being considered as possible components in skin-care and skin-health products. However, considering the potentially adverse effects of commensal skin bacteria if left free to proliferate, it is crucial to develop methodologies that are capable of maintaining bacteria viability while controlling their proliferation. Here, we encapsulate S. epidermidis in shells of increasing thickness using layer-by-layer assembly, with either a pair of synthetic polyelectrolytes or a pair of oppositely charged polysaccharides. We study the viability of the cells and their delay of growth depending on the composition of the shell, its thickness, the charge of the last deposited layer, and the degree of aggregation of the bacteria which is varied using different coating procedures-among which is a new scalable process that easily leads to large amounts of nonaggregated bacteria. We demonstrate that the growth of bacteria is not controlled by the mechanical properties of the shell but by the bacteriostatic effect of the polyelectrolyte complex, which depends on the shell thickness and charge of its outmost layer, and involves the diffusion of unpaired amine sites through the shell. The lag times of growth are sufficient to prevent proliferation for daily topical applications.
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.
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.
NASA Astrophysics Data System (ADS)
Sardesai, Chetan R.
The primary objective of this research is to explore the application of optimal control theory in nonlinear, unsteady, fluid dynamical settings. Two problems are considered: (1) control of unsteady boundary-layer separation, and (2) control of the Saltzman-Lorenz model. The unsteady boundary-layer equations are nonlinear partial differential equations that govern the eruptive events that arise when an adverse pressure gradient acts on a boundary layer at high Reynolds numbers. The Saltzman-Lorenz model consists of a coupled set of three nonlinear ordinary differential equations that govern the time-dependent coefficients in truncated Fourier expansions of Rayleigh-Renard convection and exhibit deterministic chaos. Variational methods are used to derive the nonlinear optimal control formulations based on cost functionals that define the control objective through a performance measure and a penalty function that penalizes the cost of control. The resulting formulation consists of the nonlinear state equations, which must be integrated forward in time, and the nonlinear control (adjoint) equations, which are integrated backward in time. Such coupled forward-backward time integrations are computationally demanding; therefore, the full optimal control problem for the Saltzman-Lorenz model is carried out, while the more complex unsteady boundary-layer case is solved using a sub-optimal approach. The latter is a quasi-steady technique in which the unsteady boundary-layer equations are integrated forward in time, and the steady control equation is solved at each time step. Both sub-optimal control of the unsteady boundary-layer equations and optimal control of the Saltzman-Lorenz model are found to be successful in meeting the control objectives for each problem. In the case of boundary-layer separation, the control results indicate that it is necessary to eliminate the recirculation region that is a precursor to the unsteady boundary-layer eruptions. In the case of the
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.
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.
Distributed clinical data sharing via dynamic access-control policy transformation.
Rezaeibagha, Fatemeh; Mu, Yi
2016-05-01
Data sharing in electronic health record (EHR) systems is important for improving the quality of healthcare delivery. Data sharing, however, has raised some security and privacy concerns because healthcare data could be potentially accessible by a variety of users, which could lead to privacy exposure of patients. Without addressing this issue, large-scale adoption and sharing of EHR data are impractical. The traditional solution to the problem is via encryption. Although encryption can be applied to access control, it is not applicable for complex EHR systems that require multiple domains (e.g. public and private clouds) with various access requirements. This study was carried out to address the security and privacy issues of EHR data sharing with our novel access-control mechanism, which captures the scenario of the hybrid clouds and need of access-control policy transformation, to provide secure and privacy-preserving data sharing among different healthcare enterprises. We introduce an access-control mechanism with some cryptographic building blocks and present a novel approach for secure EHR data sharing and access-control policy transformation in EHR systems for hybrid clouds. We propose a useful data sharing system for healthcare providers to handle various EHR users who have various access privileges in different cloud environments. A systematic study has been conducted on data sharing in EHR systems to provide a solution to the security and privacy issues. In conclusion, we introduce an access-control method for privacy protection of EHRs and EHR policy transformation that allows an EHR access-control policy to be transformed from a private cloud to a public cloud. This method has never been studied previously in the literature. Furthermore, we provide a protocol to demonstrate policy transformation as an application scenario. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Kundhikanjana, W.; Yang, Y.; Tanga, Q.; Zhang, K.; Lai, K.; Ma, Y.; Kelly, M. A.; Li, X. X.; Shen, Z.-X.
2013-02-01
Real-space mapping of doping concentration in semiconductor devices is of great importance for the microelectronics industry. In this work, a scanning microwave impedance microscope (MIM) is employed to resolve the local conductivity distribution of a static random access memory sample. The MIM electronics can also be adjusted to the scanning capacitance microscopy (SCM) mode, allowing both measurements on the same region. Interestingly, while the conventional SCM images match the nominal device structure, the MIM results display certain unexpected features, which originate from a thin layer of the dopant ions penetrating through the protective layers during the heavy implantation steps.
How Drug Control Policy and Practice Undermine Access to Controlled Medicines
Csete, Joanne; Wilson, Duncan; Fox, Edward; Wolfe, Daniel; Rasanathan, Jennifer J. K.
2017-01-01
Abstract Drug conventions serve as the cornerstone for domestic drug laws and impose a dual obligation upon states to prevent the misuse of controlled substances while ensuring their adequate availability for medical and scientific purposes. Despite the mandate that these obligations be enforced equally, the dominant paradigm enshrined in the drug conventions is an enforcement-heavy criminal justice response to controlled substances that prohibits and penalizes their misuse. Prioritizing restrictive control is to the detriment of ensuring adequate availability of and access to controlled medicines, thereby violating the rights of people who need them. This paper argues that the drug conventions’ prioritization of criminal justice measures—including efforts to prevent non-medical use of controlled substances—undermines access to medicines and infringes upon the right to health and the right to enjoy the benefits of scientific progress. While the effects of criminalization under drug policy limit the right to health in multiple ways, we draw on research and documented examples to highlight the impact of drug control and criminalization on access to medicines. The prioritization and protection of human rights—specifically the right to health and the right to enjoy the benefits of scientific progress—are critical to rebalancing drug policy. PMID:28630556
How Drug Control Policy and Practice Undermine Access to Controlled Medicines.
Burke-Shyne, Naomi; Csete, Joanne; Wilson, Duncan; Fox, Edward; Wolfe, Daniel; Rasanathan, Jennifer J K
2017-06-01
Drug conventions serve as the cornerstone for domestic drug laws and impose a dual obligation upon states to prevent the misuse of controlled substances while ensuring their adequate availability for medical and scientific purposes. Despite the mandate that these obligations be enforced equally, the dominant paradigm enshrined in the drug conventions is an enforcement-heavy criminal justice response to controlled substances that prohibits and penalizes their misuse. Prioritizing restrictive control is to the detriment of ensuring adequate availability of and access to controlled medicines, thereby violating the rights of people who need them. This paper argues that the drug conventions' prioritization of criminal justice measures-including efforts to prevent non-medical use of controlled substances-undermines access to medicines and infringes upon the right to health and the right to enjoy the benefits of scientific progress. While the effects of criminalization under drug policy limit the right to health in multiple ways, we draw on research and documented examples to highlight the impact of drug control and criminalization on access to medicines. The prioritization and protection of human rights-specifically the right to health and the right to enjoy the benefits of scientific progress-are critical to rebalancing drug policy.
Programmable Direct-Memory-Access Controller
NASA Technical Reports Server (NTRS)
Hendry, David F.
1990-01-01
Proposed programmable direct-memory-access controller (DMAC) operates with computer systems of 32000 series, which have 32-bit data buses and use addresses of 24 (or potentially 32) bits. Controller functions with or without help of central processing unit (CPU) and starts itself. Includes such advanced features as ability to compare two blocks of memory for equality and to search block of memory for specific value. Made as single very-large-scale integrated-circuit chip.
Programmable light-controlled shape changes in layered polymer nanocomposites.
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.
Design and FPGA implementation for MAC layer of Ethernet PON
NASA Astrophysics Data System (ADS)
Zhu, Zengxi; Lin, Rujian; Chen, Jian; Ye, Jiajun; Chen, Xinqiao
2004-04-01
Ethernet passive optical network (EPON), which represents the convergence of low-cost, high-bandwidth and supporting multiple services, appears to be one of the best candidates for the next-generation access network. The work of standardizing EPON as a solution for access network is still underway in the IEEE802.3ah Ethernet in the first mile (EFM) task force. The final release is expected in 2004. Up to now, there has been no standard application specific integrated circuit (ASIC) chip available which fulfills the functions of media access control (MAC) layer of EPON. The MAC layer in EPON system has many functions, such as point-to-point emulation (P2PE), Ethernet MAC functionality, multi-point control protocol (MPCP), network operation, administration and maintenance (OAM) and link security. To implement those functions mentioned above, an embedded real-time operating system (RTOS) and a flexible programmable logic device (PLD) with an embedded processor are used. The software and hardware functions in MAC layer are realized through programming embedded microprocessor and field programmable gate array(FPGA). Finally, some experimental results are given in this paper. The method stated here can provide a valuable reference for developing EPON MAC layer ASIC.
Navy Commercial Access Control System Did Not Effectively Mitigate Access Control Risks
2013-09-16
fOR OFFICL’tb HSE OtuN Contents Introduction Objective 1 Background 1 Review of Internal Controls 4 Finding A. NCACS Did Not Effectively...8fHh’ DODIC.-20 13·134 I v FOR OFFICL’tb HSE ONI-X Introduction Objective The objective of the audit was to determine whether the Navy... HSE ONb\\’ authorized a Common Access Card. In order to avoid the appearance of endorsing Rapidgate, Eid Passport’s trademarked product, in May 2011
A novel concept for subsonic inlet boundary-layer control
NASA Technical Reports Server (NTRS)
Miller, B. A.
1977-01-01
A self-bleeding method for boundary layer control is described and tested for a subsonic inlet designed to operate in the flowfield generated by high angles of attack. Naturally occurring surface static pressure gradients are used to remove the boundary layer from a separation-prone region of the inlet and to reinject it at a less critical location with a net performance gain. The results suggest that this self-bleeding method for boundary-layer control might be successfully applied to other inlets operating at extreme aerodynamic conditions.
Cyclone separator having boundary layer turbulence control
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.
Layer-by-layer 3-dimensional nanofiber tissue scaffold with controlled gap by electrospinning
NASA Astrophysics Data System (ADS)
Lin, Sai-Jun; Xue, Ya-Ping; Chang, Guoqing; Han, Qiao-Ling; Chen, Li-Fang; Jia, Yan-Bo; Zheng, Yu-Guo
2018-02-01
The development of three-dimensional (3D) nanofiber structures by electrospinning has drawn considerable attention in the field of tissue scaffolds. However, the generation of two dimensional mats using the conventional method limits electrospinning, the electrical charging of polymer liquids, as a means of nanofiber fabrication. In this study, we established a facile method of fabrication of layer-by-layer 3D polycaprolactone (PCL) nanofiber structures by utilizing a booklet collector with controlled morphology. Meanwhile, we explore the application of the manufactured 3D architectures in the field of tissue scaffolds. The approximately 20 μm layer-to-layer distance enhanced the ability of cells to migrate freely into tissues and induce cells in an ordered arrangement.
Experience with ActiveX control for simple channel access
DOE Office of Scientific and Technical Information (OSTI.GOV)
Timossi, C.; Nishimura, H.; McDonald, J.
2003-05-15
Accelerator control system applications at Berkeley Lab's Advanced Light Source (ALS) are typically deployed on operator consoles running Microsoft Windows 2000 and utilize EPICS[2]channel access for data access. In an effort to accommodate the wide variety of Windows based development tools and developers with little experience in network programming, ActiveX controls have been deployed on the operator stations. Use of ActiveX controls for use in the accelerator control environment has been presented previously[1]. Here we report on some of our experiences with the use and development of these controls.
Speed control system for an access gate
DOE Office of Scientific and Technical Information (OSTI.GOV)
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 outputmore » 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.« less
Accessibility, stabilizability, and feedback control of continuous orbital transfer.
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.
Breaking and Fixing Origin-Based Access Control in Hybrid Web/Mobile Application Frameworks.
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
Breaking and Fixing Origin-Based Access Control in Hybrid Web/Mobile Application Frameworks
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
Mandatory and Location-Aware Access Control for Relational Databases
NASA Astrophysics Data System (ADS)
Decker, Michael
Access control is concerned with determining which operations a particular user is allowed to perform on a particular electronic resource. For example, an access control decision could say that user Alice is allowed to perform the operation read (but not write) on the resource research report. With conventional access control this decision is based on the user's identity whereas the basic idea of Location-Aware Access Control (LAAC) is to evaluate also a user's current location when making the decision if a particular request should be granted or denied. LAAC is an interesting approach for mobile information systems because these systems are exposed to specific security threads like the loss of a device. Some data models for LAAC can be found in literature, but almost all of them are based on RBAC and none of them is designed especially for Database Management Systems (DBMS). In this paper we therefore propose a LAAC-approach for DMBS and describe a prototypical implementation of that approach that is based on database triggers.
Open versus Controlled-Access Data | Office of Cancer Genomics
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
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.…
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.
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.
Transverse jet shear layer instabilities and their control
NASA Astrophysics Data System (ADS)
Karagozian, Ann
2013-11-01
The jet in crossflow, or transverse jet, is a canonical flowfield that has relevance to engineering systems ranging from dilution jets and film cooling for gas turbine engines to thrust vector control and fuel injection in high speed aerospace vehicles to environmental control of effluent from chimney and smokestack plumes. Over the years, our UCLA Energy and Propulsion Research Lab's studies on this flowfield have focused on the dynamics of the vorticity associated with equidensity and variable density jets in crossflow, including the stability characteristics of the jet's upstream shear layer. A range of different experimental diagnostics have been used to study the jet's upstream shear layer, whereby a transition from convectively unstable behavior at high jet-to-crossflow momentum flux ratios to absolutely unstable flow at low momentum flux and/or density ratios is identified. These differences in shear layer stability characteristics have a profound effect on how one employs external excitation to control jet penetration, spread, and mixing, depending on the flow regime and specific engineering application. These control strategies, and challenges for future research directions, will be identified in this presentation.
Access control and privilege management in electronic health record: a systematic literature review.
Jayabalan, Manoj; O'Daniel, Thomas
2016-12-01
This study presents a systematic literature review of access control for electronic health record systems to protect patient's privacy. Articles from 2006 to 2016 were extracted from the ACM Digital Library, IEEE Xplore Digital Library, Science Direct, MEDLINE, and MetaPress using broad eligibility criteria, and chosen for inclusion based on analysis of ISO22600. Cryptographic standards and methods were left outside the scope of this review. Three broad classes of models are being actively investigated and developed: access control for electronic health records, access control for interoperability, and access control for risk analysis. Traditional role-based access control models are extended with spatial, temporal, probabilistic, dynamic, and semantic aspects to capture contextual information and provide granular access control. Maintenance of audit trails and facilities for overriding normal roles to allow full access in emergency cases are common features. Access privilege frameworks utilizing ontology-based knowledge representation for defining the rules have attracted considerable interest, due to the higher level of abstraction that makes it possible to model domain knowledge and validate access requests efficiently.
Cross-Layer Scheme to Control Contention Window for Per-Flow in Asymmetric Multi-Hop Networks
NASA Astrophysics Data System (ADS)
Giang, Pham Thanh; Nakagawa, Kenji
The IEEE 802.11 MAC standard for wireless ad hoc networks adopts Binary Exponential Back-off (BEB) mechanism to resolve bandwidth contention between stations. BEB mechanism controls the bandwidth allocation for each station by choosing a back-off value from one to CW according to the uniform random distribution, where CW is the contention window size. However, in asymmetric multi-hop networks, some stations are disadvantaged in opportunity of access to the shared channel and may suffer severe throughput degradation when the traffic load is large. Then, the network performance is degraded in terms of throughput and fairness. In this paper, we propose a new cross-layer scheme aiming to solve the per-flow unfairness problem and achieve good throughput performance in IEEE 802.11 multi-hop ad hoc networks. Our cross-layer scheme collects useful information from the physical, MAC and link layers of own station. This information is used to determine the optimal Contention Window (CW) size for per-station fairness. We also use this information to adjust CW size for each flow in the station in order to achieve per-flow fairness. Performance of our cross-layer scheme is examined on various asymmetric multi-hop network topologies by using Network Simulator (NS-2).
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.
A Framework for Context Sensitive Risk-Based Access Control in Medical Information Systems
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
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.
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…
Dynamic access control model for privacy preserving personalized healthcare in cloud environment.
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.
Hormone-dependent control of developmental timing through regulation of chromatin accessibility
Uyehara, Christopher M.; Nystrom, Spencer L.; Niederhuber, Matthew J.; Leatham-Jensen, Mary; Ma, Yiqin; Buttitta, Laura A.
2017-01-01
Specification of tissue identity during development requires precise coordination of gene expression in both space and time. Spatially, master regulatory transcription factors are required to control tissue-specific gene expression programs. However, the mechanisms controlling how tissue-specific gene expression changes over time are less well understood. Here, we show that hormone-induced transcription factors control temporal gene expression by regulating the accessibility of DNA regulatory elements. Using the Drosophila wing, we demonstrate that temporal changes in gene expression are accompanied by genome-wide changes in chromatin accessibility at temporal-specific enhancers. We also uncover a temporal cascade of transcription factors following a pulse of the steroid hormone ecdysone such that different times in wing development can be defined by distinct combinations of hormone-induced transcription factors. Finally, we show that the ecdysone-induced transcription factor E93 controls temporal identity by directly regulating chromatin accessibility across the genome. Notably, we found that E93 controls enhancer activity through three different modalities, including promoting accessibility of late-acting enhancers and decreasing accessibility of early-acting enhancers. Together, this work supports a model in which an extrinsic signal triggers an intrinsic transcription factor cascade that drives development forward in time through regulation of chromatin accessibility. PMID:28536147
SAFE: SPARQL Federation over RDF Data Cubes with Access Control.
Khan, Yasar; Saleem, Muhammad; Mehdi, Muntazir; Hogan, Aidan; Mehmood, Qaiser; Rebholz-Schuhmann, Dietrich; Sahay, Ratnesh
2017-02-01
Several query federation engines have been proposed for accessing public Linked Open Data sources. However, in many domains, resources are sensitive and access to these resources is tightly controlled by stakeholders; consequently, privacy is a major concern when federating queries over such datasets. In the Healthcare and Life Sciences (HCLS) domain real-world datasets contain sensitive statistical information: strict ownership is granted to individuals working in hospitals, research labs, clinical trial organisers, etc. Therefore, the legal and ethical concerns on (i) preserving the anonymity of patients (or clinical subjects); and (ii) respecting data ownership through access control; are key challenges faced by the data analytics community working within the HCLS domain. Likewise statistical data play a key role in the domain, where the RDF Data Cube Vocabulary has been proposed as a standard format to enable the exchange of such data. However, to the best of our knowledge, no existing approach has looked to optimise federated queries over such statistical data. We present SAFE: a query federation engine that enables policy-aware access to sensitive statistical datasets represented as RDF data cubes. SAFE is designed specifically to query statistical RDF data cubes in a distributed setting, where access control is coupled with source selection, user profiles and their access rights. SAFE proposes a join-aware source selection method that avoids wasteful requests to irrelevant and unauthorised data sources. In order to preserve anonymity and enforce stricter access control, SAFE's indexing system does not hold any data instances-it stores only predicates and endpoints. The resulting data summary has a significantly lower index generation time and size compared to existing engines, which allows for faster updates when sources change. We validate the performance of the system with experiments over real-world datasets provided by three clinical organisations as
Boundary-Layer Control to Helicopter Rotor Blades.
1957-01-22
Experimental investigation of boundary-layer control to helicopter rotor blades to increase forward speed capabilities. 3/4 front view. Shaft angle - 35deg. John Mc.Cloud in picture. He was a good guy.
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. (a...
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. (a...
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. (a...
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. (a...
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. (a...
Information-Flow-Based Access Control for Web Browsers
NASA Astrophysics Data System (ADS)
Yoshihama, Sachiko; Tateishi, Takaaki; Tabuchi, Naoshi; Matsumoto, Tsutomu
The emergence of Web 2.0 technologies such as Ajax and Mashup has revealed the weakness of the same-origin policy[1], the current de facto standard for the Web browser security model. We propose a new browser security model to allow fine-grained access control in the client-side Web applications for secure mashup and user-generated contents. We propose a browser security model that is based on information-flow-based access control (IBAC) to overcome the dynamic nature of the client-side Web applications and to accurately determine the privilege of scripts in the event-driven programming model.
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.
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.
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.
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
75 FR 4007 - Risk Management Controls for Brokers or Dealers With Market Access
Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-26
... 3235-AK53 Risk Management Controls for Brokers or Dealers With Market Access AGENCY: Securities and... or other persons, to implement risk management controls and supervisory procedures reasonably... access may not utilize any pre-trade risk management controls (i.e., ``unfiltered'' or ``naked'' access...
Saghafinia, Ali; Ping, Hew Wooi; Uddin, Mohammad Nasir
2013-01-01
Physical sensors have a key role in implementation of real-time vector control for an induction motor (IM) drive. This paper presents a novel boundary layer fuzzy controller (NBLFC) based on the boundary layer approach for speed control of an indirect field-oriented control (IFOC) of an induction motor (IM) drive using physical sensors. The boundary layer approach leads to a trade-off between control performances and chattering elimination. For the NBLFC, a fuzzy system is used to adjust the boundary layer thickness to improve the tracking performance and eliminate the chattering problem under small uncertainties. Also, to eliminate the chattering under the possibility of large uncertainties, the integral filter is proposed inside the variable boundary layer. In addition, the stability of the system is analyzed through the Lyapunov stability theorem. The proposed NBLFC based IM drive is implemented in real-time using digital signal processor (DSP) board TI TMS320F28335. The experimental and simulation results show the effectiveness of the proposed NBLFC based IM drive at different operating conditions.
Authenticated IGMP for Controlling Access to Multicast Distribution Tree
NASA Astrophysics Data System (ADS)
Park, Chang-Seop; Kang, Hyun-Sun
A receiver access control scheme is proposed to protect the multicast distribution tree from DoS attack induced by unauthorized use of IGMP, by extending the security-related functionality of IGMP. Based on a specific network and business model adopted for commercial deployment of IP multicast applications, a key management scheme is also presented for bootstrapping the proposed access control as well as accounting and billing for CP (Content Provider), NSP (Network Service Provider), and group members.
Access Control for Mobile Assessment Systems Using ID.
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.
Climent, Salvador; Sanchez, Antonio; Capella, Juan Vicente; Meratnia, Nirvana; Serrano, Juan Jose
2014-01-01
This survey aims to provide a comprehensive overview of the current research on underwater wireless sensor networks, focusing on the lower layers of the communication stack, and envisions future trends and challenges. It analyzes the current state-of-the-art on the physical, medium access control and routing layers. It summarizes their security threads and surveys the currently proposed studies. Current envisioned niches for further advances in underwater networks research range from efficient, low-power algorithms and modulations to intelligent, energy-aware routing and medium access control protocols. PMID:24399155
Climent, Salvador; Sanchez, Antonio; Capella, Juan Vicente; Meratnia, Nirvana; Serrano, Juan Jose
2014-01-06
This survey aims to provide a comprehensive overview of the current research on underwater wireless sensor networks, focusing on the lower layers of the communication stack, and envisions future trends and challenges. It analyzes the current state-of-the-art on the physical, medium access control and routing layers. It summarizes their security threads and surveys the currently proposed studies. Current envisioned niches for further advances in underwater networks research range from efficient, low-power algorithms and modulations to intelligent, energy-aware routing and medium access control protocols.
Morphology control of layer-structured gallium selenide nanowires.
Peng, Hailin; Meister, Stefan; Chan, Candace K; Zhang, Xiao Feng; Cui, Yi
2007-01-01
Layer-structured group III chalcogenides have highly anisotropic properties and are attractive materials for stable photocathodes and battery electrodes. We report the controlled synthesis and characterization of layer-structured GaSe nanowires via a catalyst-assisted vapor-liquid-solid (VLS) growth mechanism during GaSe powder evaporation. GaSe nanowires consist of Se-Ga-Ga-Se layers stacked together via van der Waals interactions to form belt-shaped nanowires with a growth direction along the [11-20], width along the [1-100], and height along the [0001] direction. Nanobelts exhibit a variety of morphologies including straight, zigzag, and saw-tooth shapes. These morphologies are realized by controlling the growth temperature and time so that the actual catalysts have a chemical composition of Au, Au-Ga alloy, or Ga. The participation of Ga in the VLS catalyst is important for achieving different morphologies of GaSe. In addition, GaSe nanotubes are also prepared by a slow growth process.
McManus, Donald P.; Raso, Giovanna; Utzinger, Jürg; Xiao, Shui-Yuan; Yu, Dong-Bao; Zhao, Zheng-Yuan; Li, Yue-Sheng
2013-01-01
Background Access to health care is a major requirement in improving health and fostering socioeconomic development. In the People's Republic of China (P.R. China), considerable changes have occurred in the social, economic, and health systems with a shift from a centrally planned to a socialist market economy. This brought about great benefits and new challenges, particularly for vertical disease control programs, including schistosomiasis. We explored systemic barriers in access to equitable and effective control of schistosomiasis. Methodology Between August 2002 and February 2003, 66 interviews with staff from anti-schistosomiasis control stations and six focus group discussions with health personnel were conducted in the Dongting Lake area, Hunan Province. Additionally, 79 patients with advanced schistosomiasis japonica were interviewed. The health access livelihood framework was utilized to examine availability, accessibility, affordability, adequacy, and acceptability of schistosomiasis-related health care. Principal Findings We found sufficient availability of infrastructure and human resources at most control stations. Many patients with advanced schistosomiasis resided in non-endemic or moderately endemic areas, however, with poor accessibility to disease-specific knowledge and specialized health services. Moreover, none of the patients interviewed had any form of health insurance, resulting in high out-of-pocket expenditure or unaffordable care. Reports on the adequacy and acceptability of care were mixed. Conclusions/Significance There is a need to strengthen health awareness and schistosomiasis surveillance in post-transmission control settings, as well as to reduce diagnostic and treatment costs. Further studies are needed to gain a multi-layered, in-depth understanding of remaining barriers, so that the ultimate goal of schistosomiasis elimination in P.R. China can be reached. PMID:23936580
NASA Astrophysics Data System (ADS)
Lei, Qingyu; Golalikhani, Maryam; Davidson, Bruce A.; Liu, Guozhen; Schlom, Darrell G.; Qiao, Qiao; Zhu, Yimei; Chandrasena, Ravini U.; Yang, Weibing; Gray, Alexander X.; Arenholz, Elke; Farrar, Andrew K.; Tenne, Dmitri A.; Hu, Minhui; Guo, Jiandong; Singh, Rakesh K.; Xi, Xiaoxing
2017-12-01
Advancements in nanoscale engineering of oxide interfaces and heterostructures have led to discoveries of emergent phenomena and new artificial materials. Combining the strengths of reactive molecular-beam epitaxy and pulsed-laser deposition, we show here, with examples of Sr1+xTi1-xO3+δ, Ruddlesden-Popper phase Lan+1NinO3n+1 (n = 4), and LaAl1+yO3(1+0.5y)/SrTiO3 interfaces, that atomic layer-by-layer laser molecular-beam epitaxy significantly advances the state of the art in constructing oxide materials with atomic layer precision and control over stoichiometry. With atomic layer-by-layer laser molecular-beam epitaxy we have produced conducting LaAlO3/SrTiO3 interfaces at high oxygen pressures that show no evidence of oxygen vacancies, a capability not accessible by existing techniques. The carrier density of the interfacial two-dimensional electron gas thus obtained agrees quantitatively with the electronic reconstruction mechanism.
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…
Open access publishing, article downloads, and citations: randomised controlled trial
Lewenstein, Bruce V; Simon, Daniel H; Booth, James G; Connolly, Mathew J L
2008-01-01
Objective To measure the effect of free access to the scientific literature on article downloads and citations. Design Randomised controlled trial. Setting 11 journals published by the American Physiological Society. Participants 1619 research articles and reviews. Main outcome measures Article readership (measured as downloads of full text, PDFs, and abstracts) and number of unique visitors (internet protocol addresses). Citations to articles were gathered from the Institute for Scientific Information after one year. Interventions Random assignment on online publication of articles published in 11 scientific journals to open access (treatment) or subscription access (control). Results Articles assigned to open access were associated with 89% more full text downloads (95% confidence interval 76% to 103%), 42% more PDF downloads (32% to 52%), and 23% more unique visitors (16% to 30%), but 24% fewer abstract downloads (−29% to −19%) than subscription access articles in the first six months after publication. Open access articles were no more likely to be cited than subscription access articles in the first year after publication. Fifty nine per cent of open access articles (146 of 247) were cited nine to 12 months after publication compared with 63% (859 of 1372) of subscription access articles. Logistic and negative binomial regression analysis of article citation counts confirmed no citation advantage for open access articles. Conclusions Open access publishing may reach more readers than subscription access publishing. No evidence was found of a citation advantage for open access articles in the first year after publication. The citation advantage from open access reported widely in the literature may be an artefact of other causes. PMID:18669565
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.
Boundary-Layer Control: In Memory of Bill Reynolds
NASA Astrophysics Data System (ADS)
Kim, John
2004-11-01
Professor Bill Reynolds (1933-2004) inspired many students and colleagues with his never-ending curiosity and thought-provoking ideas. Bill's relentless energy, together with his hallmark can-do character and do-it-yourself attitude, led to many seminal contributions to mechanical engineering in general, and fluid mechanics in particular. He has left a lasting impact on many of us, especially for those who had the privilege of working closely with him. Some of my current work on boundary-layer control, the use of neural networks in particular, were inspired by many discussions with Bill. He was among the first to see the potential of control-theoretic approaches for flow control, which has become the main thrust of my current research. Without his continued encouragement, I would not have been deeply involved in this line of research; and perhaps, we would not have seen the current flurry of research activities in applying modern control theories to flow control. In memory of Bill Reynolds, who himself has contributed much to flow control, an analysis of boundary-layer control from a linear system perspective will be presented.
A federated capability-based access control mechanism for internet of things (IoTs)
NASA Astrophysics Data System (ADS)
Xu, Ronghua; Chen, Yu; Blasch, Erik; Chen, Genshe
2018-05-01
The prevalence of Internet of Things (IoTs) allows heterogeneous embedded smart devices to collaboratively provide intelligent services with or without human intervention. While leveraging the large-scale IoT-based applications like Smart Gird and Smart Cities, IoT also incurs more concerns on privacy and security. Among the top security challenges that IoTs face is that access authorization is critical in resource and information protection over IoTs. Traditional access control approaches, like Access Control Lists (ACL), Role-based Access Control (RBAC) and Attribute-based Access Control (ABAC), are not able to provide a scalable, manageable and efficient mechanisms to meet requirement of IoT systems. The extraordinary large number of nodes, heterogeneity as well as dynamicity, necessitate more fine-grained, lightweight mechanisms for IoT devices. In this paper, a federated capability-based access control (FedCAC) framework is proposed to enable an effective access control processes to devices, services and information in large scale IoT systems. The federated capability delegation mechanism, based on a propagation tree, is illustrated for access permission propagation. An identity-based capability token management strategy is presented, which involves registering, propagation and revocation of the access authorization. Through delegating centralized authorization decision-making policy to local domain delegator, the access authorization process is locally conducted on the service provider that integrates situational awareness (SAW) and customized contextual conditions. Implemented and tested on both resources-constrained devices, like smart sensors and Raspberry PI, and non-resource-constrained devices, like laptops and smart phones, our experimental results demonstrate the feasibility of the proposed FedCAC approach to offer a scalable, lightweight and fine-grained access control solution to IoT systems connected to a system network.
Fertility Effects of Abortion and Birth Control Pill Access for Minors
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
Fertility effects of abortion and birth control pill access for minors.
Guldi, Melanie
2008-11-01
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' birth rates. 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 birth rates dropped as a result of abortion access as well as evidence that birth control pill access led to a drop in birth rates among whites.
Turbulent boundary layer under the control of different schemes
NASA Astrophysics Data System (ADS)
Qiao, Z. X.; Zhou, Y.; Wu, Z.
2017-06-01
This work explores experimentally the control of a turbulent boundary layer over a flat plate based on wall perturbation generated by piezo-ceramic actuators. Different schemes are investigated, including the feed-forward, the feedback, and the combined feed-forward and feedback strategies, with a view to suppressing the near-wall high-speed events and hence reducing skin friction drag. While the strategies may achieve a local maximum drag reduction slightly less than their counterpart of the open-loop control, the corresponding duty cycles are substantially reduced when compared with that of the open-loop control. The results suggest a good potential to cut down the input energy under these control strategies. The fluctuating velocity, spectra, Taylor microscale and mean energy dissipation are measured across the boundary layer with and without control and, based on the measurements, the flow mechanism behind the control is proposed.
Turbulent boundary layer under the control of different schemes.
Qiao, Z X; Zhou, Y; Wu, Z
2017-06-01
This work explores experimentally the control of a turbulent boundary layer over a flat plate based on wall perturbation generated by piezo-ceramic actuators. Different schemes are investigated, including the feed-forward, the feedback, and the combined feed-forward and feedback strategies, with a view to suppressing the near-wall high-speed events and hence reducing skin friction drag. While the strategies may achieve a local maximum drag reduction slightly less than their counterpart of the open-loop control, the corresponding duty cycles are substantially reduced when compared with that of the open-loop control. The results suggest a good potential to cut down the input energy under these control strategies. The fluctuating velocity, spectra, Taylor microscale and mean energy dissipation are measured across the boundary layer with and without control and, based on the measurements, the flow mechanism behind the control is proposed.
Turbulent boundary layer under the control of different schemes
Zhou, Y.; Wu, Z.
2017-01-01
This work explores experimentally the control of a turbulent boundary layer over a flat plate based on wall perturbation generated by piezo-ceramic actuators. Different schemes are investigated, including the feed-forward, the feedback, and the combined feed-forward and feedback strategies, with a view to suppressing the near-wall high-speed events and hence reducing skin friction drag. While the strategies may achieve a local maximum drag reduction slightly less than their counterpart of the open-loop control, the corresponding duty cycles are substantially reduced when compared with that of the open-loop control. The results suggest a good potential to cut down the input energy under these control strategies. The fluctuating velocity, spectra, Taylor microscale and mean energy dissipation are measured across the boundary layer with and without control and, based on the measurements, the flow mechanism behind the control is proposed. PMID:28690409
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.
Evaluation of modified work zone traffic control devices at business accesses
DOT National Transportation Integrated Search
2001-01-01
Modified work zone traffic control devices at business accesses were evaluated on two Oregon Department of Transportation (ODOT) projects in 1999 and 2000. On one section project, blue Temporary Business Access" signs were used at business accesses d...
Elastic wave manipulation by using a phase-controlling meta-layer
NASA Astrophysics Data System (ADS)
Shen, Xiaohui; Sun, Chin-Teh; Barnhart, Miles V.; Huang, Guoliang
2018-03-01
In this work, a high pass meta-layer for elastic waves is proposed. An elastic phase-controlling meta-layer is theoretically realized using parallel and periodically arranged metamaterial sections based on the generalized Snell's law. The elastic meta-layer is composed of periodically repeated supercells, in which the frequency dependent elastic properties of the metamaterial are used to control a phase gradient at the interface between the meta-layer and conventional medium. It is analytically and numerically demonstrated that with a normal incident longitudinal wave, the wave propagation characteristics can be directly manipulated by the periodic length of the meta-layer element at the sub-wavelength scale. It is found that propagation of the incident wave through the interface is dependent on whether the working wavelength is longer or shorter than the periodic length of the meta-layer element. Specifically, a mode conversion of the P-wave to an SV-wave is investigated as the incident wave passes through the meta-layer region. Since the most common and damaging elastic waves in civil and mechanical industries are in the low frequency region, the work in this paper has great potential in the seismic shielding, engine vibration isolation, and other highly dynamic fields.
A slotted access control protocol for metropolitan WDM ring networks
NASA Astrophysics Data System (ADS)
Baziana, P. A.; Pountourakis, I. E.
2009-03-01
In this study we focus on the serious scalability problems that many access protocols for WDM ring networks introduce due to the use of a dedicated wavelength per access node for either transmission or reception. We propose an efficient slotted MAC protocol suitable for WDM ring metropolitan area networks. The proposed network architecture employs a separate wavelength for control information exchange prior to the data packet transmission. Each access node is equipped with a pair of tunable transceivers for data communication and a pair of fixed tuned transceivers for control information exchange. Also, each access node includes a set of fixed delay lines for synchronization reasons; to keep the data packets, while the control information is processed. An efficient access algorithm is applied to avoid both the data wavelengths and the receiver collisions. In our protocol, each access node is capable of transmitting and receiving over any of the data wavelengths, facing the scalability issues. Two different slot reuse schemes are assumed: the source and the destination stripping schemes. For both schemes, performance measures evaluation is provided via an analytic model. The analytical results are validated by a discrete event simulation model that uses Poisson traffic sources. Simulation results show that the proposed protocol manages efficient bandwidth utilization, especially under high load. Also, comparative simulation results prove that our protocol achieves significant performance improvement as compared with other WDMA protocols which restrict transmission over a dedicated data wavelength. Finally, performance measures evaluation is explored for diverse numbers of buffer size, access nodes and data wavelengths.
Access Control for Cooperation Systems Based on Group Situation
NASA Astrophysics Data System (ADS)
Kim, Minsoo; Joshi, James B. D.; Kim, Minkoo
Cooperation systems characterize many emerging environments such as ubiquitous and pervasive systems. Agent based cooperation systems have been proposed in the literature to address challenges of such emerging application environments. A key aspect of such agent based cooperation system is the group situation that changes dynamically and governs the requirements of the cooperation. While individual agent context is important, the overall cooperation behavior is more driven by the group context because of relationships and interactions between agents. Dynamic access control based on group situation is a crucial challenge in such cooperation systems. In this paper we propose a dynamic role based access control model for cooperation systems based on group situation. The model emphasizes capability based agent to role mapping and group situation based permission assignment to allow capturing dynamic access policies that evolve continuously.
[Access control management in electronic health records: a systematic literature review].
Carrión Señor, Inmaculada; Fernández Alemán, José Luis; Toval, Ambrosio
2012-01-01
This study presents the results of a systematic literature review of aspects related to access control in electronic health records systems, wireless security and privacy and security training for users. Information sources consisted of original articles found in Medline, ACM Digital Library, Wiley InterScience, IEEE Digital Library, Science@Direct, MetaPress, ERIC, CINAHL and Trip Database, published between January 2006 and January 2011. A total of 1,208 articles were extracted using a predefined search string and were reviewed by the authors. The final selection consisted of 24 articles. Of the selected articles, 21 dealt with access policies in electronic health records systems. Eleven articles discussed whether access to electronic health records should be granted by patients or by health organizations. Wireless environments were only considered in three articles. Finally, only four articles explicitly mentioned that technical training of staff and/or patients is required. Role-based access control is the preferred mechanism to deploy access policy by the designers of electronic health records. In most systems, access control is managed by users and health professionals, which promotes patients' right to control personal information. Finally, the security of wireless environments is not usually considered. However, one line of research is eHealth in mobile environments, called mHealth. Copyright © 2011 SESPAS. Published by Elsevier Espana. All rights reserved.
Policy reconciliation for access control in dynamic cross-enterprise collaborations
NASA Astrophysics Data System (ADS)
Preuveneers, D.; Joosen, W.; Ilie-Zudor, E.
2018-03-01
In dynamic cross-enterprise collaborations, different enterprises form a - possibly temporary - business relationship. To integrate their business processes, enterprises may need to grant each other limited access to their information systems. Authentication and authorization are key to secure information handling. However, access control policies often rely on non-standardized attributes to describe the roles and permissions of their employees which convolutes cross-organizational authorization when business relationships evolve quickly. Our framework addresses the managerial overhead of continuous updates to access control policies for enterprise information systems to accommodate disparate attribute usage. By inferring attribute relationships, our framework facilitates attribute and policy reconciliation, and automatically aligns dynamic entitlements during the evaluation of authorization decisions. We validate our framework with a Industry 4.0 motivating scenario on networked production where such dynamic cross-enterprise collaborations are quintessential. The evaluation reveals the capabilities and performance of our framework, and illustrates the feasibility of liberating the security administrator from manually provisioning and aligning attributes, and verifying the consistency of access control policies for cross-enterprise collaborations.
[Public control and equity of access to hospitals under non-State public administration].
Carneiro Junior, Nivaldo; Elias, Paulo Eduardo
2006-10-01
To analyze social health organizations in the light of public control and the guarantee of equity of access to health services. Utilizing the case study technique, two social health organizations in the metropolitan region of São Paulo were selected. The analytical categories were equity of access and public control, and these were based on interviews with key informants and technical-administrative reports. It was observed that the overall funding and administrative control of the social health organizations are functions of the state administrator. The presence of a local administrator is important for ensuring equity of access. Public control is expressed through supervisory actions, by means of accounting and financial procedures. Equity of access and public control are not taken into consideration in the administration of these organizations. The central question lies in the capacity of the public authorities to have a presence in implementing this model at the local level, thereby ensuring equity of access and taking public control into consideration.
Toward Privacy-preserving Content Access Control for Information Centric Networking
2014-03-01
REPORT Toward Privacy-preserving Content Access Control for Information Centric Networking 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Information...regardless the security mechanisms provided by different content hosting servers. However, using ABE has a drawback that the enforced content access...Encryption (ABE) is a flexible approach to enforce the content access policies regardless the security mechanisms provided by different content hosting
75 FR 80886 - Third Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2010-12-23
... 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 meeting: Airport Security Access Control Systems (Update to... Committee 224: Airport Security Access Control Systems. DATES: The meeting will be held January 13, 2011...
75 FR 61819 - First Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2010-10-06
... 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 meeting: Airport Security Access Control Systems (Update to... Committee 224: Airport Security Access Control Systems. DATES: The meeting will be held November 2, 2010...
An approach to access control in electronic health record.
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.
75 FR 71790 - Second Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2010-11-24
... Committee 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 meeting: Airport Security Access Control Systems (Update to... Committee 224: Airport Security Access Control Systems. DATES: The meeting will be held December 9, 2010...
76 FR 9632 - Fifth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2011-02-18
... 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 meeting: Airport Security Access Control Systems (Update to... Committee 224: Airport Security Access Control Systems. DATES: The meeting will be held March 10, 2011, from...
76 FR 3931 - Fourth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2011-01-21
... Committee 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 Meeting: Airport Security Access Control Systems (Update to... Committee 224: Airport Security Access Control Systems. DATES: The meeting will be held February 8, 2011...
76 FR 16470 - Sixth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2011-03-23
... 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 meeting: Airport Security Access Control Systems (Update to... Committee 224: Airport Security Access Control Systems DATES: The meeting will be held April 13, 2011, from...
Empowering citizens with access control mechanisms to their personal health resources.
Calvillo, J; Román, I; Roa, L M
2013-01-01
Advancements in information and communication technologies have allowed the development of new approaches to the management and use of healthcare resources. Nowadays it is possible to address complex issues such as meaningful access to distributed data or communication and understanding among heterogeneous systems. As a consequence, the discussion focuses on the administration of the whole set of resources providing knowledge about a single subject of care (SoC). New trends make the SoC administrator and responsible for all these elements (related to his/her demographic data, health, well-being, social conditions, etc.) and s/he is granted the ability of controlling access to them by third parties. The subject of care exchanges his/her passive role without any decision capacity for an active one allowing to control who accesses what. We study the necessary access control infrastructure to support this approach and develop mechanisms based on semantic tools to assist the subject of care with the specification of access control policies. This infrastructure is a building block of a wider scenario, the Person-Oriented Virtual Organization (POVO), aiming at integrating all the resources related to each citizen's health-related data. The POVO covers the wide range and heterogeneity of available healthcare resources (e.g., information sources, monitoring devices, or software simulation tools) and grants each SoC the access control to them. Several methodological issues are crucial for the design of the targeted infrastructure. The distributed system concept and focus are reviewed from the service oriented architecture (SOA) perspective. The main frameworks for the formalization of distributed system architectures (Reference Model-Open Distributed Processing, RM-ODP; and Model Driven Architecture, MDA) are introduced, as well as how the use of the Unified Modelling Language (UML) is standardized. The specification of access control policies and decision making mechanisms
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.
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 areas...
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 areas...
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 areas...
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 areas...
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 areas...
Federal Register 2010, 2011, 2012, 2013, 2014
2012-11-30
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S... Access Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of the seventeenth meeting of the RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting...
78 FR 7850 - Nineteenth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2013-02-04
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S... Access Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of the nineteenth meeting of the RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting...
Federal Register 2010, 2011, 2012, 2013, 2014
2012-04-30
... Committee 224, Airport Security Access Control Systems. AGENCY: Federal Aviation Administration (FAA), U.S... Access Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of the thirteenth meeting of RTCA Special Committee 224, Airport Security Access Control Systems DATES: The meeting will be...
77 FR 15448 - Twelfth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2012-03-15
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S... Access Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of the twelfth meeting of RTCA Special Committee 224, Airport Security Access Control Systems DATES: The meeting will be...
Automating Access Control Logics in Simple Type Theory with LEO-II
NASA Astrophysics Data System (ADS)
Benzmüller, Christoph
Garg and Abadi recently proved that prominent access control logics can be translated in a sound and complete way into modal logic S4. We have previously outlined how normal multimodal logics, including monomodal logics K and S4, can be embedded in simple type theory and we have demonstrated that the higher-order theorem prover LEO-II can automate reasoning in and about them. In this paper we combine these results and describe a sound (and complete) embedding of different access control logics in simple type theory. Employing this framework we show that the off the shelf theorem prover LEO-II can be applied to automate reasoning in and about prominent access control logics.
NASA Astrophysics Data System (ADS)
Cornaglia, Bruno; Young, Gavin; Marchetta, Antonio
2015-12-01
Fixed broadband network deployments are moving inexorably to the use of Next Generation Access (NGA) technologies and architectures. These NGA deployments involve building fiber infrastructure increasingly closer to the customer in order to increase the proportion of fiber on the customer's access connection (Fibre-To-The-Home/Building/Door/Cabinet… i.e. FTTx). This increases the speed of services that can be sold and will be increasingly required to meet the demands of new generations of video services as we evolve from HDTV to "Ultra-HD TV" with 4k and 8k lines of video resolution. However, building fiber access networks is a costly endeavor. It requires significant capital in order to cover any significant geographic coverage. Hence many companies are forming partnerships and joint-ventures in order to share the NGA network construction costs. One form of such a partnership involves two companies agreeing to each build to cover a certain geographic area and then "cross-selling" NGA products to each other in order to access customers within their partner's footprint (NGA coverage area). This is tantamount to a bi-lateral wholesale partnership. The concept of Fixed Access Network Sharing (FANS) is to address the possibility of sharing infrastructure with a high degree of flexibility for all network operators involved. By providing greater configuration control over the NGA network infrastructure, the service provider has a greater ability to define the network and hence to define their product capabilities at the active layer. This gives the service provider partners greater product development autonomy plus the ability to differentiate from each other at the active network layer.
Controlling user access to electronic resources without password
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.
Jaïdi, Faouzi; Labbene-Ayachi, Faten; Bouhoula, Adel
2016-12-01
Nowadays, e-healthcare is a main advancement and upcoming technology in healthcare industry that contributes to setting up automated and efficient healthcare infrastructures. Unfortunately, several security aspects remain as main challenges towards secure and privacy-preserving e-healthcare systems. From the access control perspective, e-healthcare systems face several issues due to the necessity of defining (at the same time) rigorous and flexible access control solutions. This delicate and irregular balance between flexibility and robustness has an immediate impact on the compliance of the deployed access control policy. To address this issue, the paper defines a general framework to organize thinking about verifying, validating and monitoring the compliance of access control policies in the context of e-healthcare databases. We study the problem of the conformity of low level policies within relational databases and we particularly focus on the case of a medical-records management database defined in the context of a Medical Information System. We propose an advanced solution for deploying reliable and efficient access control policies. Our solution extends the traditional lifecycle of an access control policy and allows mainly managing the compliance of the policy. We refer to an example to illustrate the relevance of our proposal.
Gain control by layer six in cortical circuits of vision.
Olsen, Shawn R; Bortone, Dante S; Adesnik, Hillel; Scanziani, Massimo
2012-02-22
After entering the cerebral cortex, sensory information spreads through six different horizontal neuronal layers that are interconnected by vertical axonal projections. It is believed that through these projections layers can influence each other's response to sensory stimuli, but the specific role that each layer has in cortical processing is still poorly understood. Here we show that layer six in the primary visual cortex of the mouse has a crucial role in controlling the gain of visually evoked activity in neurons of the upper layers without changing their tuning to orientation. This gain modulation results from the coordinated action of layer six intracortical projections to superficial layers and deep projections to the thalamus, with a substantial role of the intracortical circuit. This study establishes layer six as a major mediator of cortical gain modulation and suggests that it could be a node through which convergent inputs from several brain areas can regulate the earliest steps of cortical visual processing.
Controlling user access to electronic resources without password
Smith, Fred Hewitt
2017-08-22
Described herein are devices and techniques for remotely controlling user access to a restricted computer resource. The process includes obtaining an image from a communication device of a user. An individual and a landmark are identified within the image. Determinations are made that the individual is the user and that the landmark is a predetermined landmark. Access to a restricted computing resource is granted based on the determining that the individual is the user and that the landmark is the predetermined landmark. Other embodiments are disclosed.
Global Access-controlled Transfer e-frame (GATe)
DOE Office of Scientific and Technical Information (OSTI.GOV)
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.
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.
Optoelectronic Control of Spin and Pseudospin in Layered WSe2
NASA Astrophysics Data System (ADS)
Jones, Aaron
2014-03-01
Coherent manipulation of spin-like quantum numbers facilitates the development of new quantum technologies. Layered transition metal dichalcogenides provide an ideal laboratory to exploit such dynamic control of spin, pseudospin, and their interplay. Here, we discuss two examples based on monolayer and bilayer WSe2. Due to the inversion asymmetry in monolayer WSe2, valley pseudospins, which index the degenerate extrema of the energy-momentum bands, possess circularly polarized optical selection rules. In addition to the generation of valley polarization through optical pumping of valley excitons, we demonstrate the creation of a coherent superposition between valley states in monolayer WSe2 by linearly polarized excitation. On the other hand, bilayer WSe2 provides an additional quantum degree of freedom, the layer pseudospin, which corresponds to layer polarization. In AB stacked bilayers, we find the real spin is locked to layer pseudospin for a given valley, which results in the suppression of spin relaxation and electrical control of spin Zeeman splitting without an applied magnetic field. Additionally, we obtain spectroscopic evidence of interlayer and intralayer trion species, an important step toward coherent optical control in van der Waals 2D heterostructures. Aaron Jones partially supported by NSF Grant No. DGE-0718124.
Access and accounting schemes of wireless broadband
NASA Astrophysics Data System (ADS)
Zhang, Jian; Huang, Benxiong; Wang, Yan; Yu, Xing
2004-04-01
In this paper, two wireless broadband access and accounting schemes were introduced. There are some differences in the client and the access router module between them. In one scheme, Secure Shell (SSH) protocol is used in the access system. The SSH server makes the authentication based on private key cryptography. The advantage of this scheme is the security of the user's information, and we have sophisticated access control. In the other scheme, Secure Sockets Layer (SSL) protocol is used the access system. It uses the technology of public privacy key. Nowadays, web browser generally combines HTTP and SSL protocol and we use the SSL protocol to implement the encryption of the data between the clients and the access route. The schemes are same in the radius sever part. Remote Authentication Dial in User Service (RADIUS), as a security protocol in the form of Client/Sever, is becoming an authentication/accounting protocol for standard access to the Internet. It will be explained in a flow chart. In our scheme, the access router serves as the client to the radius server.
Layered compression for high-precision depth data.
Miao, Dan; Fu, Jingjing; Lu, Yan; Li, Shipeng; Chen, Chang Wen
2015-12-01
With the development of depth data acquisition technologies, access to high-precision depth with more than 8-b depths has become much easier and determining how to efficiently represent and compress high-precision depth is essential for practical depth storage and transmission systems. In this paper, we propose a layered high-precision depth compression framework based on an 8-b image/video encoder to achieve efficient compression with low complexity. Within this framework, considering the characteristics of the high-precision depth, a depth map is partitioned into two layers: 1) the most significant bits (MSBs) layer and 2) the least significant bits (LSBs) layer. The MSBs layer provides rough depth value distribution, while the LSBs layer records the details of the depth value variation. For the MSBs layer, an error-controllable pixel domain encoding scheme is proposed to exploit the data correlation of the general depth information with sharp edges and to guarantee the data format of LSBs layer is 8 b after taking the quantization error from MSBs layer. For the LSBs layer, standard 8-b image/video codec is leveraged to perform the compression. The experimental results demonstrate that the proposed coding scheme can achieve real-time depth compression with satisfactory reconstruction quality. Moreover, the compressed depth data generated from this scheme can achieve better performance in view synthesis and gesture recognition applications compared with the conventional coding schemes because of the error control algorithm.
An improved task-role-based access control model for G-CSCW applications
NASA Astrophysics Data System (ADS)
He, Chaoying; Chen, Jun; Jiang, Jie; Han, Gang
2005-10-01
Access control is an important and popular security mechanism for multi-user applications. GIS-based Computer Supported Cooperative Work (G-CSCW) application is one of such applications. This paper presents an improved Task-Role-Based Access Control (X-TRBAC) model for G-CSCW applications. The new model inherits the basic concepts of the old ones, such as role and task. Moreover, it has introduced two concepts, i.e. object hierarchy and operation hierarchy, and the corresponding rules to improve the efficiency of permission definition in access control models. The experiments show that the method can simplify the definition of permissions, and it is more applicable for G-CSCW applications.
36 CFR 1256.70 - What controls access to national security-classified information?
Code of Federal Regulations, 2010 CFR
2010-07-01
... national security-classified information? 1256.70 Section 1256.70 Parks, Forests, and Public Property... HISTORICAL MATERIALS Access to Materials Containing National Security-Classified Information § 1256.70 What controls access to national security-classified information? (a) The declassification of and public access...
Federal Register 2010, 2011, 2012, 2013, 2014
2013-05-24
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S... Access Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of the twenty-second meeting of the RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting...
Federal Register 2010, 2011, 2012, 2013, 2014
2013-04-12
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S... Access Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of the twenty first meeting of the RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting...
Control of magnetic direction in multi-layer ferromagnetic devices by bias voltage
You, Chun-Yeol; Bader, Samuel D.
2001-01-01
A system for controlling the direction of magnetization of materials comprising a ferromagnetic device with first and second ferromagnetic layers. The ferromagnetic layers are disposed such that they combine to form an interlayer with exchange coupling. An insulating layer and a spacer layer are located between the first and second ferromagnetic layers. A direct bias voltage is applied to the interlayer exchange coupling, causing the direction of magnetization of the second ferromagnetic layer to change. This change of magnetization direction occurs in the absence of any applied external magnetic field.
NASA Astrophysics Data System (ADS)
Nakajima, Ryo; Azuma, Atsushi; Yoshida, Hayato; Shimizu, Tomohiro; Ito, Takeshi; Shingubara, Shoso
2018-06-01
Resistive random access memory (ReRAM) devices with a HfO2 dielectric layer have been studied extensively owing to the good reproducibility of their SET/RESET switching properties. Furthermore, it was reported that a thin Hf layer next to a HfO2 layer stabilized switching properties because of the oxygen scavenging effect. In this work, we studied the Hf thickness dependence of the resistance switching characteristics of a Ti/Hf/HfO2/Au ReRAM device. It is found that the optimum Hf thickness is approximately 10 nm to obtain good reproducibility of SET/RESET voltages with a small RESET current. However, when the Hf thickness was very small (∼2 nm), the device failed after the first RESET process owing to the very large RESET current. In the case of a very thick Hf layer (∼20 nm), RESET did not occur owing to the formation of a leaky dielectric layer. We observed the occurrence of multiple resistance states in the RESET process of the device with a Hf thickness of 10 nm by increasing the RESET voltage stepwise.
Functional Basis for Efficient Physical Layer Classical Control in Quantum Processors
NASA Astrophysics Data System (ADS)
Ball, Harrison; Nguyen, Trung; Leong, Philip H. W.; Biercuk, Michael J.
2016-12-01
The rapid progress seen in the development of quantum-coherent devices for information processing has motivated serious consideration of quantum computer architecture and organization. One topic which remains open for investigation and optimization relates to the design of the classical-quantum interface, where control operations on individual qubits are applied according to higher-level algorithms; accommodating competing demands on performance and scalability remains a major outstanding challenge. In this work, we present a resource-efficient, scalable framework for the implementation of embedded physical layer classical controllers for quantum-information systems. Design drivers and key functionalities are introduced, leading to the selection of Walsh functions as an effective functional basis for both programing and controller hardware implementation. This approach leverages the simplicity of real-time Walsh-function generation in classical digital hardware, and the fact that a wide variety of physical layer controls, such as dynamic error suppression, are known to fall within the Walsh family. We experimentally implement a real-time field-programmable-gate-array-based Walsh controller producing Walsh timing signals and Walsh-synthesized analog waveforms appropriate for critical tasks in error-resistant quantum control and noise characterization. These demonstrations represent the first step towards a unified framework for the realization of physical layer controls compatible with large-scale quantum-information processing.
Application of Layered Perforation Profile Control Technique to Low Permeable Reservoir
NASA Astrophysics Data System (ADS)
Wei, Sun
2018-01-01
it is difficult to satisfy the demand of profile control of complex well section and multi-layer reservoir by adopting the conventional profile control technology, therefore, a research is conducted on adjusting the injection production profile with layered perforating parameters optimization. i.e. in the case of coproduction for multi-layer, water absorption of each layer is adjusted by adjusting the perforating parameters, thus to balance the injection production profile of the whole well section, and ultimately enhance the oil displacement efficiency of water flooding. By applying the relationship between oil-water phase percolation theory/perforating damage and capacity, a mathematic model of adjusting the injection production profile with layered perforating parameters optimization, besides, perforating parameters optimization software is programmed. Different types of optimization design work are carried out according to different geological conditions and construction purposes by using the perforating optimization design software; furthermore, an application test is done for low permeable reservoir, and the water injection profile tends to be balanced significantly after perforation with optimized parameters, thereby getting a good application effect on site.
Cruz-Piris, Luis; Rivera, Diego; Marsa-Maestre, Ivan; de la Hoz, Enrique; Velasco, Juan R
2018-03-20
Internet growth has generated new types of services where the use of sensors and actuators is especially remarkable. These services compose what is known as the Internet of Things (IoT). One of the biggest current challenges is obtaining a safe and easy access control scheme for the data managed in these services. We propose integrating IoT devices in an access control system designed for Web-based services by modelling certain IoT communication elements as resources. This would allow us to obtain a unified access control scheme between heterogeneous devices (IoT devices, Internet-based services, etc.). To achieve this, we have analysed the most relevant communication protocols for these kinds of environments and then we have proposed a methodology which allows the modelling of communication actions as resources. Then, we can protect these resources using access control mechanisms. The validation of our proposal has been carried out by selecting a communication protocol based on message exchange, specifically Message Queuing Telemetry Transport (MQTT). As an access control scheme, we have selected User-Managed Access (UMA), an existing Open Authorization (OAuth) 2.0 profile originally developed for the protection of Internet services. We have performed tests focused on validating the proposed solution in terms of the correctness of the access control system. Finally, we have evaluated the energy consumption overhead when using our proposal.
2018-01-01
Internet growth has generated new types of services where the use of sensors and actuators is especially remarkable. These services compose what is known as the Internet of Things (IoT). One of the biggest current challenges is obtaining a safe and easy access control scheme for the data managed in these services. We propose integrating IoT devices in an access control system designed for Web-based services by modelling certain IoT communication elements as resources. This would allow us to obtain a unified access control scheme between heterogeneous devices (IoT devices, Internet-based services, etc.). To achieve this, we have analysed the most relevant communication protocols for these kinds of environments and then we have proposed a methodology which allows the modelling of communication actions as resources. Then, we can protect these resources using access control mechanisms. The validation of our proposal has been carried out by selecting a communication protocol based on message exchange, specifically Message Queuing Telemetry Transport (MQTT). As an access control scheme, we have selected User-Managed Access (UMA), an existing Open Authorization (OAuth) 2.0 profile originally developed for the protection of Internet services. We have performed tests focused on validating the proposed solution in terms of the correctness of the access control system. Finally, we have evaluated the energy consumption overhead when using our proposal. PMID:29558406
Simple measurement-based admission control for DiffServ access networks
NASA Astrophysics Data System (ADS)
Lakkakorpi, Jani
2002-07-01
In order to provide good Quality of Service (QoS) in a Differentiated Services (DiffServ) network, a dynamic admission control scheme is definitely needed as an alternative to overprovisioning. In this paper, we present a simple measurement-based admission control (MBAC) mechanism for DiffServ-based access networks. Instead of using active measurements only or doing purely static bookkeeping with parameter-based admission control (PBAC), the admission control decisions are based on bandwidth reservations and periodically measured & exponentially averaged link loads. If any link load on the path between two endpoints is over the applicable threshold, access is denied. Link loads are periodically sent to Bandwidth Broker (BB) of the routing domain, which makes the admission control decisions. The information needed in calculating the link loads is retrieved from the router statistics. The proposed admission control mechanism is verified through simulations. Our results prove that it is possible to achieve very high bottleneck link utilization levels and still maintain good QoS.
Jiang, Bo; Li, Cuiling; Qian, Huayu; Hossain, Md Shahriar A; Malgras, Victor; Yamauchi, Yusuke
2017-06-26
Although multilayer films have been extensively reported, most compositions have been limited to non-catalytically active materials (e.g. polymers, proteins, lipids, or nucleic acids). Herein, we report the preparation of binder-free multilayer metallic mesoporous films with sufficient accessibility for high electrocatalytic activity by using a programmed electrochemical strategy. By precisely tuning the deposition potential and duration, multilayer mesoporous architectures consisting of alternating mesoporous Pd layers and mesoporous PdPt layers with controlled layer thicknesses can be synthesized within a single electrolyte, containing polymeric micelles as soft templates. This novel architecture, combining the advantages of bimetallic alloys, multilayer architectures, and mesoporous structures, exhibits high electrocatalytic activity for both the methanol oxidation reaction (MOR) and the ethanol oxidation reaction (EOR). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Nurse practitioners and controlled substances prescriptive authority: improving access to care.
Ambrose, Michelle A; Tarlier, Denise S
2013-03-01
In 2007, Health Canada proposed a new framework to regulate prescriptive authority for controlled substances, titled New Classes of Practitioners Regulations (NCPR). The new regulatory framework was passed in November 2012; it gives nurse practitioners (NPs), midwives and podiatrists the authority to prescribe controlled medications under the Controlled Drugs and Substances Act. It is expected that authorizing NPs to write prescriptions for certain controlled substances commonly used in primary care will enhance flexibility and timeliness in primary care service delivery. Studies from the United States have shown positive outcomes in primary care access, decreased healthcare costs and the evolution and advancement of the NP role when prescriptive authority was expanded to include controlled substances. The purpose of this paper is to examine how NPs' prescriptive authority for controlled substances affects access to primary care and NP role development. Three key issues identified from the experience of one group of NPs in the United States (access to care, professional autonomy and prescriber knowledge) offer insight into the practice changes that may be anticipated for NPs in Canada now that they have acquired prescriptive authority for controlled substances. Recommendations are offered to assist nurse leaders and educators to best support NPs as they take on this new and important role responsibility.
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.
Pressure-Aware Control Layer Optimization for Flow-Based Microfluidic Biochips.
Wang, Qin; Xu, Yue; Zuo, Shiliang; Yao, Hailong; Ho, Tsung-Yi; Li, Bing; Schlichtmann, Ulf; Cai, Yici
2017-12-01
Flow-based microfluidic biochips are attracting increasing attention with successful biomedical applications. One critical issue with flow-based microfluidic biochips is the large number of microvalves that require peripheral control pins. Even using the broadcasting addressing scheme, i.e., one control pin controls multiple microvalves simultaneously, thousands of microvalves would still require hundreds of control prins, which is unrealistic. To address this critical challenge in control scalability, the control-layer multiplexer is introduced to effectively reduce the number of control pins into log scale of the number of microvalves. There are two practical design issues with the control-layer multiplexer: (1) the reliability issue caused by the frequent control-valve switching, and (2) the pressure degradation problem caused by the control-valve switching without pressure refreshing from the pressure source. This paper addresses these two design issues by the proposed Hamming-distance-based switching sequence optimization method and the XOR-based pressure refreshing method. Simulation results demonstrate the effectiveness and efficiency of the proposed methods with an average 77.2% (maximum 89.6%) improvement in total pressure refreshing cost, and an average 88.5% (maximum 90.0%) improvement in pressure deviation.
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.
76 FR 59481 - Ninth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2011-09-26
... Control Systems (Update to DO-230B): Agenda October 20, 2011 Welcome/Introductions/Administrative Remarks... 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 meeting: Airport Security Access Control Systems. SUMMARY...
76 FR 50811 - Eighth Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2011-08-16
... Control Systems (Update to DO-230B): Agenda September 15, 2011 Welcome/Introductions/Administrative... Committee 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 meeting: Airport Security Access Control Systems. SUMMARY...
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.
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.
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.
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
Vibration control of multiferroic fibrous composite plates using active constrained layer damping
NASA Astrophysics Data System (ADS)
Kattimani, S. C.; Ray, M. C.
2018-06-01
Geometrically nonlinear vibration control of fiber reinforced magneto-electro-elastic or multiferroic fibrous composite plates using active constrained layer damping treatment has been investigated. The piezoelectric (BaTiO3) fibers are embedded in the magnetostrictive (CoFe2O4) matrix forming magneto-electro-elastic or multiferroic smart composite. A three-dimensional finite element model of such fiber reinforced magneto-electro-elastic plates integrated with the active constrained layer damping patches is developed. Influence of electro-elastic, magneto-elastic and electromagnetic coupled fields on the vibration has been studied. The Golla-Hughes-McTavish method in time domain is employed for modeling a constrained viscoelastic layer of the active constrained layer damping treatment. The von Kármán type nonlinear strain-displacement relations are incorporated for developing a three-dimensional finite element model. Effect of fiber volume fraction, fiber orientation and boundary conditions on the control of geometrically nonlinear vibration of the fiber reinforced magneto-electro-elastic plates is investigated. The performance of the active constrained layer damping treatment due to the variation of piezoelectric fiber orientation angle in the 1-3 Piezoelectric constraining layer of the active constrained layer damping treatment has also been emphasized.
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.
Energy-efficient boarder node medium access control protocol for wireless sensor networks.
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
Energy-Efficient Boarder Node Medium Access Control Protocol for Wireless Sensor Networks
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
76 FR 38742 - Seventh Meeting: RTCA Special Committee 224: Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2011-07-01
... Control Systems (Update to DO-230B): Agenda July 15, 2011 Welcome/Introductions/Administrative Remarks... Committee 224: Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of RTCA Special Committee 224 meeting: Airport Security Access Control Systems (Update to...
A Flexible Component based Access Control Architecture for OPeNDAP Services
NASA Astrophysics Data System (ADS)
Kershaw, Philip; Ananthakrishnan, Rachana; Cinquini, Luca; Lawrence, Bryan; Pascoe, Stephen; Siebenlist, Frank
2010-05-01
Network data access services such as OPeNDAP enable widespread access to data across user communities. However, without ready means to restrict access to data for such services, data providers and data owners are constrained from making their data more widely available. Even with such capability, the range of different security technologies available can make interoperability between services and user client tools a challenge. OPeNDAP is a key data access service in the infrastructure under development to support the CMIP5 (Couple Model Intercomparison Project Phase 5). The work is being carried out as part of an international collaboration including the US Earth System Grid and Curator projects and the EU funded IS-ENES and Metafor projects. This infrastructure will bring together Petabytes of climate model data and associated metadata from over twenty modelling centres around the world in a federation with a core archive mirrored at three data centres. A security system is needed to meet the requirements of organisations responsible for model data including the ability to restrict data access to registered users, keep them up to date with changes to data and services, audit access and protect finite computing resources. Individual organisations have existing tools and services such as OPeNDAP with which users in the climate research community are already familiar. The security system should overlay access control in a way which maintains the usability and ease of access to these services. The BADC (British Atmospheric Data Centre) has been working in collaboration with the Earth System Grid development team and partner organisations to develop the security architecture. OpenID and MyProxy were selected at an early stage in the ESG project to provide single sign-on capability across the federation of participating organisations. Building on the existing OPeNDAP specification an architecture based on pluggable server side components has been developed at the BADC
Access Control for Home Data Sharing: Attitudes, Needs and Practices
2009-10-01
cameras, mobile phones and portable music players make creating and interacting with this content easy. Home users are increasingly interested in...messages, photos, home videos, journal files and home musical recordings. Many participants considered unauthorized access by strangers, acquaintances...configuration does not allow users to share different subsets of music with different people. Facebook supplies rich, customizable access controls for
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.
Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices
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.
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, DEPARTMENT OF TRANSPORTATION LICENSING LICENSE TO OPERATE A LAUNCH SITE Responsibilities of a Licensee § 420...
Optical control of graphene plasmon using liquid crystal layer 29K New One
2017-03-01
AFRL-AFOSR-UK-TR-2017-0014 Optical control of graphene plasmon using liquid crystal layer 29K New One Viktor Yuriyovych Reshetnyak SCIENCE AND... plasmon using liquid crystal layer 29K New One 5a. CONTRACT NUMBER 5b. GRANT NUMBER STCU-P652 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) Viktor...the basic research and establishes possible optical ways to control the surface plasmon polariton in graphene layer. A system comprises the graphene
Active Vibration Control of Elastic Beam by Means of Shape Memory Alloy Layers
NASA Technical Reports Server (NTRS)
Chen, Q.; Levy, C.
1996-01-01
The mathematical model of a flexible beam covered with shape memory alloy (SMA) layers is presented. The SMA layers are used as actuators, which are capable of changing their elastic modulus and recovery stress, thus changing the natural frequency of, and adjusting the excitation to, the vibrating beam. The frequency factor variation as a function of SMA Young's modulus, SMA layer thickness and beam thickness is discussed. Also control of the beam employing an optimal linear control law is evaluated. The control results indicate how the system reacts to various levels of excitation input through the non-homogeneous recovery shear term of the governing differential equation.
Membrane catalyst layer for fuel cells
Wilson, Mahlon S.
1993-01-01
A gas reaction fuel cell incorporates a thin catalyst layer between a solid polymer electrolyte (SPE) membrane and a porous electrode backing. The catalyst layer is preferably less than about 10 .mu.m in thickness with a carbon supported platinum catalyst loading less than about 0.35 mgPt/cm.sup.2. The film is formed as an ink that is spread and cured on a film release blank. The cured film is then transferred to the SPE membrane and hot pressed into the surface to form a catalyst layer having a controlled thickness and catalyst distribution. Alternatively, the catalyst layer is formed by applying a Na.sup.+ form of a perfluorosulfonate ionomer directly to the membrane, drying the film at a high temperature, and then converting the film back to the protonated form of the ionomer. The layer has adequate gas permeability so that cell performance is not affected and has a density and particle distribution effective to optimize proton access to the catalyst and electronic continuity for electron flow from the half-cell reaction occurring at the catalyst.
77 FR 2343 - Eleventh Meeting: RTCA Special Committee 224, Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2012-01-17
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S... Control Systems. SUMMARY: The FAA is issuing this notice to advise the public of the eleventh meeting of RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting will be held...
Mu, Bin; Lu, Chunyin; Liu, Peng
2011-02-01
The disintegration-controllable stimuli-responsive polyelectrolyte multilayer microcapsules have been fabricated via the covalent layer-by-layer assembly between the amino groups of chitosan (CS) and the aldehyde groups of the oxidized sodium alginate (OSA) onto the sacrificial templates (polystyrene sulfonate, PSS) which was removed by dialysis subsequently. The covalent crosslinking bonds of the multilayer microcapsules were confirmed by FTIR analysis. The TEM analysis showed that the diameter of the multilayer microcapsules was <200nm. The diameter of the multilayer microcapsules decreased with the increasing of the pH values or the ionic strength. The pH and ionic strength dual-responsive multilayer microcapsules were stable in acidic and neutral media while they could disintegrate only at strong basic media. Copyright © 2010 Elsevier B.V. All rights reserved.
The OPL Access Control Policy Language
NASA Astrophysics Data System (ADS)
Alm, Christopher; Wolf, Ruben; Posegga, Joachim
Existing policy languages suffer from a limited ability of directly and elegantly expressing high-level access control principles such as history-based separation of duty [22], binding of duty [26], context constraints [24], Chinese wall properties [10], and obligations [20]. It is often difficult to extend a language in order to retrofit these features once required or it is necessary to use complicated and complex language constructs to express such concepts. The latter, however, is cumbersome and error-prone for humans dealing with policy administration.
Diffusion-Based Design of Multi-Layered Ophthalmic Lenses for Controlled Drug Release
Pimenta, Andreia F. R.; Serro, Ana Paula; Paradiso, Patrizia; Saramago, Benilde
2016-01-01
The study of ocular drug delivery systems has been one of the most covered topics in drug delivery research. One potential drug carrier solution is the use of materials that are already commercially available in ophthalmic lenses for the correction of refractive errors. In this study, we present a diffusion-based mathematical model in which the parameters can be adjusted based on experimental results obtained under controlled conditions. The model allows for the design of multi-layered therapeutic ophthalmic lenses for controlled drug delivery. We show that the proper combination of materials with adequate drug diffusion coefficients, thicknesses and interfacial transport characteristics allows for the control of the delivery of drugs from multi-layered ophthalmic lenses, such that drug bursts can be minimized, and the release time can be maximized. As far as we know, this combination of a mathematical modelling approach with experimental validation of non-constant activity source lamellar structures, made of layers of different materials, accounting for the interface resistance to the drug diffusion, is a novel approach to the design of drug loaded multi-layered contact lenses. PMID:27936138
76 FR 67019 - Tenth Meeting: RTCA Special Committee 224, Airport Security Access Control
Federal Register 2010, 2011, 2012, 2013, 2014
2011-10-28
... 224, Airport Security Access Control AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Notice of RTCA Special Committee 224, Airport Security Access Control. SUMMARY: The... (Pub. L. 92-463, 5 U.S.C., App.), notice is hereby given for a Special Committee 224, Airport Security...
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.
A contextual role-based access control authorization model for electronic patient record.
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.
Color coding of control room displays: the psychocartography of visual layering effects.
Van Laar, Darren; Deshe, Ofer
2007-06-01
To evaluate which of three color coding methods (monochrome, maximally discriminable, and visual layering) used to code four types of control room display format (bars, tables, trend, mimic) was superior in two classes of task (search, compare). It has recently been shown that color coding of visual layers, as used in cartography, may be used to color code any type of information display, but this has yet to be fully evaluated. Twenty-four people took part in a 2 (task) x 3 (coding method) x 4 (format) wholly repeated measures design. The dependent variables assessed were target location reaction time, error rates, workload, and subjective feedback. Overall, the visual layers coding method produced significantly faster reaction times than did the maximally discriminable and the monochrome methods for both the search and compare tasks. No significant difference in errors was observed between conditions for either task type. Significantly less perceived workload was experienced with the visual layers coding method, which was also rated more highly than the other coding methods on a 14-item visual display quality questionnaire. The visual layers coding method is superior to other color coding methods for control room displays when the method supports the user's task. The visual layers color coding method has wide applicability to the design of all complex information displays utilizing color coding, from the most maplike (e.g., air traffic control) to the most abstract (e.g., abstracted ecological display).
Control of Alq3 wetting layer thickness via substrate surface functionalization.
Tsoi, Shufen; Szeto, Bryan; Fleischauer, Michael D; Veinot, Jonathan G C; Brett, Michael J
2007-06-05
The effects of substrate surface energy and vapor deposition rate on the initial growth of porous columnar tris(8-hydroxyquinoline)aluminum (Alq3) nanostructures were investigated. Alq3 nanostructures thermally evaporated onto as-supplied Si substrates bearing an oxide were observed to form a solid wetting layer, likely caused by an interfacial energy mismatch between the substrate and Alq3. Wetting layer thickness control is important for potential optoelectronic applications. A dramatic decrease in wetting layer thickness was achieved by depositing Alq3 onto alkyltrichlorosilane-derivatized Si/oxide substrates. Similar effects were noted with increasing deposition rates. These two effects enable tailoring of the wetting layer thickness.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ranjan, Alok, E-mail: alok.ranjan@us.tel.com; Wang, Mingmei; Sherpa, Sonam D.
2016-05-15
Atomic or layer by layer etching of silicon exploits temporally segregated self-limiting adsorption and material removal steps to mitigate the problems associated with continuous or quasicontinuous (pulsed) plasma processes: selectivity loss, damage, and profile control. Successful implementation of atomic layer etching requires careful choice of the plasma parameters for adsorption and desorption steps. This paper illustrates how process parameters can be arrived at through basic scaling exercises, modeling and simulation, and fundamental experimental tests of their predictions. Using chlorine and argon plasma in a radial line slot antenna plasma source as a platform, the authors illustrate how cycle time, ionmore » energy, and radical to ion ratio can be manipulated to manage the deviation from ideality when cycle times are shortened or purges are incomplete. Cell based Monte Carlo feature scale modeling is used to illustrate profile outcomes. Experimental results of atomic layer etching processes are illustrated on silicon line and space structures such that iso-dense bias and aspect ratio dependent free profiles are produced. Experimental results also illustrate the profile control margin as processes move from atomic layer to multilayer by layer etching. The consequence of not controlling contamination (e.g., oxygen) is shown to result in deposition and roughness generation.« less
Accessible solitons of fractional dimension
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhong, Wei-Ping, E-mail: zhongwp6@126.com; Texas A&M University at Qatar, P.O. Box 23874, Doha; Belić, Milivoj
We demonstrate that accessible solitons described by an extended Schrödinger equation with the Laplacian of fractional dimension can exist in strongly nonlocal nonlinear media. The soliton solutions of the model are constructed by two special functions, the associated Legendre polynomials and the Laguerre polynomials in the fraction-dimensional space. Our results show that these fractional accessible solitons form a soliton family which includes crescent solitons, and asymmetric single-layer and multi-layer necklace solitons. -- Highlights: •Analytic solutions of a fractional Schrödinger equation are obtained. •The solutions are produced by means of self-similar method applied to the fractional Schrödinger equation with parabolic potential.more » •The fractional accessible solitons form crescent, asymmetric single-layer and multilayer necklace profiles. •The model applies to the propagation of optical pulses in strongly nonlocal nonlinear media.« less
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.
50 CFR 648.262 - Effort-control program for red crab 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 red crab... UNITED STATES Management Measures for the Atlantic Deep-Sea Red Crab Fishery § 648.262 Effort-control program for red crab limited access vessels. (a) General. A vessel issued a limited access red crab permit...
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.
NASA Astrophysics Data System (ADS)
SUN, D.; TONG, L.
2002-05-01
A detailed model for the beams with partially debonded active constraining damping (ACLD) treatment is presented. In this model, the transverse displacement of the constraining layer is considered to be non-identical to that of the host structure. In the perfect bonding region, the viscoelastic core is modelled to carry both peel and shear stresses, while in the debonding area, it is assumed that no peel and shear stresses be transferred between the host beam and the constraining layer. The adhesive layer between the piezoelectric sensor and the host beam is also considered in this model. In active control, the positive position feedback control is employed to control the first mode of the beam. Based on this model, the incompatibility of the transverse displacements of the active constraining layer and the host beam is investigated. The passive and active damping behaviors of the ACLD patch with different thicknesses, locations and lengths are examined. Moreover, the effects of debonding of the damping layer on both passive and active control are examined via a simulation example. The results show that the incompatibility of the transverse displacements is remarkable in the regions near the ends of the ACLD patch especially for the high order vibration modes. It is found that a thinner damping layer may lead to larger shear strain and consequently results in a larger passive and active damping. In addition to the thickness of the damping layer, its length and location are also key factors to the hybrid control. The numerical results unveil that edge debonding can lead to a reduction of both passive and active damping, and the hybrid damping may be more sensitive to the debonding of the damping layer than the passive damping.
Health Information System Role-Based Access Control Current Security Trends and Challenges.
de Carvalho Junior, Marcelo Antonio; Bandiera-Paiva, Paulo
2018-01-01
This article objective is to highlight implementation characteristics, concerns, or limitations over role-based access control (RBAC) use on health information system (HIS) using industry-focused literature review of current publishing for that purpose. Based on the findings, assessment for indication of RBAC is obsolete considering HIS authorization control needs. We have selected articles related to our investigation theme "RBAC trends and limitations" in 4 different sources related to health informatics or to the engineering technical field. To do so, we have applied the following search query string: "Role-Based Access Control" OR "RBAC" AND "Health information System" OR "EHR" AND "Trends" OR "Challenges" OR "Security" OR "Authorization" OR "Attacks" OR "Permission Assignment" OR "Permission Relation" OR "Permission Mapping" OR "Constraint". We followed PRISMA applicable flow and general methodology used on software engineering for systematic review. 20 articles were selected after applying inclusion and exclusion criteria resulting contributions from 10 different countries. 17 articles advocate RBAC adaptations. The main security trends and limitations mapped were related to emergency access, grant delegation, and interdomain access control. Several publishing proposed RBAC adaptations and enhancements in order to cope current HIS use characteristics. Most of the existent RBAC studies are not related to health informatics industry though. There is no clear indication of RBAC obsolescence for HIS use.
Innovation in Layer-by-Layer Assembly.
Richardson, Joseph J; Cui, Jiwei; Björnmalm, Mattias; Braunger, Julia A; Ejima, Hirotaka; Caruso, Frank
2016-12-14
Methods for depositing thin films are important in generating functional materials for diverse applications in a wide variety of fields. Over the last half-century, the layer-by-layer assembly of nanoscale films has received intense and growing interest. This has been fueled by innovation in the available materials and assembly technologies, as well as the film-characterization techniques. In this Review, we explore, discuss, and detail innovation in layer-by-layer assembly in terms of past and present developments, and we highlight how these might guide future advances. A particular focus is on conventional and early developments that have only recently regained interest in the layer-by-layer assembly field. We then review unconventional assemblies and approaches that have been gaining popularity, which include inorganic/organic hybrid materials, cells and tissues, and the use of stereocomplexation, patterning, and dip-pen lithography, to name a few. A relatively recent development is the use of layer-by-layer assembly materials and techniques to assemble films in a single continuous step. We name this "quasi"-layer-by-layer assembly and discuss the impacts and innovations surrounding this approach. Finally, the application of characterization methods to monitor and evaluate layer-by-layer assembly is discussed, as innovation in this area is often overlooked but is essential for development of the field. While we intend for this Review to be easily accessible and act as a guide to researchers new to layer-by-layer assembly, we also believe it will provide insight to current researchers in the field and help guide future developments and innovation.
In-depth porosity control of mesoporous silicon layers by an anodization current adjustment
NASA Astrophysics Data System (ADS)
Lascaud, J.; Defforge, T.; Certon, D.; Valente, D.; Gautier, G.
2017-12-01
The formation of thick mesoporous silicon layers in P+-type substrates leads to an increase in the porosity from the surface to the interface with silicon. The adjustment of the current density during the electrochemical etching of porous silicon is an intuitive way to control the layer in-depth porosity. The duration and the current density during the anodization were varied to empirically model porosity variations with layer thickness and build a database. Current density profiles were extracted from the model in order to etch layer with in-depth control porosity. As a proof of principle, an 80 μm-thick porous silicon multilayer was synthetized with decreasing porosities from 55% to 35%. The results show that the assessment of the in-depth porosity could be significantly enhanced by taking into account the pure chemical etching of the layer in the hydrofluoric acid-based electrolyte.
78 FR 16757 - Twentieth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2013-03-18
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security... meeting of the RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting...
77 FR 64838 - Sixteenth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2012-10-23
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security... meeting of the RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting...
77 FR 55894 - Fifteenth Meeting: RTCA Special Committee 224, Airport Security Access Control Systems
Federal Register 2010, 2011, 2012, 2013, 2014
2012-09-11
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security... meeting of the RTCA Special Committee 224, Airport Security Access Control Systems DATES: The meeting will...
Control and Visualization of a Shear Layer Over a Weapons Bay
NASA Astrophysics Data System (ADS)
Schmit, Ryan; Raman, Ganesh; Lourenco, Luis; Kibens, Valdis
2005-11-01
In July 2005, the AFRL program Flow Control Analysis Development (FlowCAD) tested the High Frequency Excitation Active Flow Control for Supersonic Weapons Release (HIFEX) generic weapons bay model in the Boeing's Polysonic windtunnel facility. The 10% scaled weapons bay with an L/D of 5 was tested at Mach 1.82. Several flow control devices were tested, including: the goalpost, a wedge and pin configuration, and the splash jet, to determine their effectiveness at reducing the sound pressure levels inside the weapons bay. The results show the wedge and splash jet are equally effective at reducing the peak Rossiter tone by 20 dB. The main objective of this test was to visualize the shear layer over the weapons bay cavity. By examining the cavity shear layer with a 10 kHz Focused Schlieren system the effects from the flow control devices can be understood to produce a more effective flow control device in the future.
Suganuma, Y; Dhirani, A-A
2011-04-01
The present study explores a novel apertured microchip conductance detector (AMCD) that is sensitive to dielectric constant. Fashioned on silicon oxide/silicon using optical microlithography, the detector has novel parallel-plate geometry with a top mesh electrode, a middle apertured insulator, and a bottom conducting electrode. This monolithic apertured architecture is planar and may be provided with a thin insulator layer enabling large capacitances, while the top mesh electrode and middle apertured-insulator enable access to regions of the capacitor where electric fields are strong. Hence, the detector is sensitive yet mechanically robust. To test its response, the AMCD was immersed in various solvents, namely water, methanol, acetonitrile, and hexanes. Its response was found to vary in proportion to the solvents' respective dielectric constants. The AMCD was also able to distinguish quantitatively the presence of various molecules in solution, including molecules with chromophores [such as acetylsalicylic acid (ASA)] in methanol and those without chrompohores [such as polyethylene glycol 200 Daltons (PEG200)] in methanol or water. The universal nature of dielectric constant and the microchip detector's sensitivity point to a wide range of potential applications. © 2011 American Institute of Physics
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
Effects of boundary-layer separation controllers on a desktop fume hood.
Huang, Rong Fung; Chen, Jia-Kun; Hsu, Ching Min; Hung, Shuo-Fu
2016-10-02
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).
Numerical simulation of the control of the three-dimensional transition process in boundary layers
NASA Technical Reports Server (NTRS)
Kral, L. D.; Fasel, H. F.
1990-01-01
Surface heating techniques to control the three-dimensional laminar-turbulent transition process are numerically investigated for a water boundary layer. The Navier-Stokes and energy equations are solved using a fully implicit finite difference/spectral method. The spatially evolving boundary layer is simulated. Results of both passive and active methods of control are shown for small amplitude two-dimensional and three-dimensional disturbance waves. Control is also applied to the early stages of the secondary instability process using passive or active control techniques.
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.
Session Types for Access and Information Flow Control
NASA Astrophysics Data System (ADS)
Capecchi, Sara; Castellani, Ilaria; Dezani-Ciancaglini, Mariangiola; Rezk, Tamara
We consider a calculus for multiparty sessions with delegation, enriched with security levels for session participants and data. We propose a type system that guarantees both session safety and a form of access control. Moreover, this type system ensures secure information flow, including controlled forms of declassification. In particular, the type system prevents leaks that could result from an unrestricted use of the control constructs of the calculus, such as session opening, selection, branching and delegation. We illustrate the use of our type system with a number of examples, which reveal an interesting interplay between the constraints used in security type systems and those used in session types to ensure properties like communication safety and session fidelity.
Non-linear coherent mode interactions and the control of shear layers
NASA Technical Reports Server (NTRS)
Nikitopoulos, D. E.; Liu, J. T. C.
1990-01-01
A nonlinear integral formulation, based on local linear stability considerations, is used to study the collective interactions between discrete wave-modes associated with large-scale structures and the mean flow in a developing shear layer. Aspects of shear layer control are examined in light of the sensitivity of these interactions to the initial frequency parameter, modal energy contents and modal phases. Manipulation of the large-scale structure is argued to be an effective means of controlling the flow, including the small-scale turbulence dominated region far downstream. Cases of fundamental, 1st and 2nd subharmonic forcing are discussed in conjunction with relevant experiments.
An action-based fine-grained access control mechanism for structured documents and its application.
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.
NASA Astrophysics Data System (ADS)
Weintraub, Benjamin; Chang, Sehoon; Singamaneni, Srikanth; Han, Won Hee; Choi, Young Jin; Bae, Joonho; Kirkham, Melanie; Tsukruk, Vladimir V.; Deng, Yulin
2008-10-01
A simple, scalable, and cost-effective technique for controlling the growth density of ZnO nanorod arrays based on a layer-by-layer polyelectrolyte polymer film is demonstrated. The ZnO nanorods were synthesized using a low temperature (T = 90 °C), solution-based method. The density-control technique utilizes a polymer thin film pre-coated on the substrate to control the mass transport of the reactant to the substrate. The density-controlled arrays were investigated as potential field emission candidates. The field emission results revealed that an emitter density of 7 nanorods µm-2 and a tapered nanorod morphology generated a high field enhancement factor of 5884. This novel technique shows promise for applications in flat panel display technology.
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
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.
Controlled-release fertilizer composition substantially coated with an impermeable layer
DOE Office of Scientific and Technical Information (OSTI.GOV)
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.
Burning Graphene Layer-by-Layer
Ermakov, Victor A.; Alaferdov, Andrei V.; Vaz, Alfredo R.; Perim, Eric; Autreto, Pedro A. S.; Paupitz, Ricardo; Galvao, Douglas S.; Moshkalev, Stanislav A.
2015-01-01
Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in “cold-wall” reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material. PMID:26100466
Multi-Layer E-Textile Circuits
NASA Technical Reports Server (NTRS)
Dunne, Lucy E.; Bibeau, Kaila; Mulligan, Lucie; Frith, Ashton; Simon, Cory
2012-01-01
Stitched e-textile circuits facilitate wearable, flexible, comfortable wearable technology. However, while stitched methods of e-textile circuits are common, multi-layer circuit creation remains a challenge. Here, we present methods of stitched multi-layer circuit creation using accessible tools and techniques.
An Action-Based Fine-Grained Access Control Mechanism for Structured Documents and Its Application
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
A Network Access Control Framework for 6LoWPAN Networks
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
Secure Access Control and Large Scale Robust Representation for Online Multimedia Event Detection
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
Secure access control and large scale robust representation for online multimedia event detection.
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.
Plasma-based actuators for turbulent boundary layer control in transonic flow
NASA Astrophysics Data System (ADS)
Budovsky, A. D.; Polivanov, P. A.; Vishnyakov, O. I.; Sidorenko, A. A.
2017-10-01
The study is devoted to development of methods for active control of flow structure typical for the aircraft wings in transonic flow with turbulent boundary layer. The control strategy accepted in the study was based on using of the effects of plasma discharges interaction with miniature geometrical obstacles of various shapes. The conceptions were studied computationally using 3D RANS, URANS approaches. The results of the computations have shown that energy deposition can significantly change the flow pattern over the obstacles increasing their influence on the flow in boundary layer region. Namely, one of the most interesting and promising data were obtained for actuators basing on combination of vertical wedge with asymmetrical plasma discharge. The wedge considered is aligned with the local streamlines and protruding in the flow by 0.4-0.8 of local boundary layer thickness. The actuator produces negligible distortion of the flow at the absence of energy deposition. Energy deposition along the one side of the wedge results in longitudinal vortex formation in the wake of the actuator providing momentum exchange in the boundary layer. The actuator was manufactured and tested in wind tunnel experiments at Mach number 1.5 using the model of flat plate. The experimental data obtained by PIV proved the availability of the actuator.
Boundary-layer and wake measurements on a swept, circulation-control wing
NASA Technical Reports Server (NTRS)
Spaid, Frank W.; Keener, Earl R.
1987-01-01
Wind-tunnel measurements of boundary-layer and wake velocity profiles and surface static pressure distributions are presented for a swept, circulation-control wing. The model is an aspect-ratio-four semispan wing mounted on the tunnel side wall at a sweep angle of 45 deg. A full-span, tangential, rearward blowing, circulation-control slot is located ahead of the trailing edge on the upper surface. Flow surveys were obtained at mid-semispan at freestream Mach numbers of 0.425 and 0.70. Boundary-layer profiles measured on the forward portions of the wing are approximately streamwise and two dimensional. The flow in the vicinity of the jet exit and in the near wake is highly three dimensional. The jet flow near the slot on the Coanda surface is directed normal to the slot. Near-wake surveys show large outboard flows at the center of the wake. At Mach 0.425 and a 5-deg angle of attack, a range of jet-blowing rates was found for which an abrupt transition from incipient separation to attached flow occurs in the boundary layer upstream of the slot. The variation in the lower-surface separation location with blowing rate was determined from boundary-layer measurements at Mach 0.425.
Interface magnetic anisotropy for monatomic layer-controlled Co/Ni epitaxial multilayers
NASA Astrophysics Data System (ADS)
Shioda, A.; Seki, T.; Shimada, J.; Takanashi, K.
2015-05-01
The magnetic properties for monatomic layer (ML)-controlled Co/Ni epitaxial multilayers were investigated in order to evaluate the interface magnetic anisotropy energy (Ks) between Ni and Co layers. The Co/Ni epitaxial multilayers were prepared on an Al2O3 (11-20) substrate with V/Au buffer layers. The value of Ks was definitely larger than that for the textured Co/Ni grown on a thermally oxidized Si substrate. We consider that the sharp interface for the epitaxial Co/Ni played a role to increase the value of Ks, which also enabled us to obtain perpendicular magnetization even for the 1 ML-Co/1 ML-Ni multilayer.
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.
Federal Register 2010, 2011, 2012, 2013, 2014
2013-07-22
... Committee 224, Airport Security Access Control Systems AGENCY: Federal Aviation Administration (FAA), U.S. Department of Transportation (DOT). ACTION: Meeting Notice of RTCA Special Committee 224, Airport Security... meeting of the RTCA Special Committee 224, Airport Security Access Control Systems. DATES: The meeting...
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.
Optimal vibration control of a rotating plate with self-sensing active constrained layer damping
NASA Astrophysics Data System (ADS)
Xie, Zhengchao; Wong, Pak Kin; Lo, Kin Heng
2012-04-01
This paper proposes a finite element model for optimally controlled constrained layer damped (CLD) rotating plate with self-sensing technique and frequency-dependent material property in both the time and frequency domain. Constrained layer damping with viscoelastic material can effectively reduce the vibration in rotating structures. However, most existing research models use complex modulus approach to model viscoelastic material, and an additional iterative approach which is only available in frequency domain has to be used to include the material's frequency dependency. It is meaningful to model the viscoelastic damping layer in rotating part by using the anelastic displacement fields (ADF) in order to include the frequency dependency in both the time and frequency domain. Also, unlike previous ones, this finite element model treats all three layers as having the both shear and extension strains, so all types of damping are taken into account. Thus, in this work, a single layer finite element is adopted to model a three-layer active constrained layer damped rotating plate in which the constraining layer is made of piezoelectric material to work as both the self-sensing sensor and actuator under an linear quadratic regulation (LQR) controller. After being compared with verified data, this newly proposed finite element model is validated and could be used for future research.
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.
Feasibility Assessment of a Fine-Grained Access Control Model on Resource Constrained Sensors.
Uriarte Itzazelaia, Mikel; Astorga, Jasone; Jacob, Eduardo; Huarte, Maider; Romaña, Pedro
2018-02-13
Upcoming smart scenarios enabled by the Internet of Things (IoT) envision smart objects that provide services that can adapt to user behavior or be managed to achieve greater productivity. In such environments, smart things are inexpensive and, therefore, constrained devices. However, they are also critical components because of the importance of the information that they provide. Given this, strong security is a requirement, but not all security mechanisms in general and access control models in particular are feasible. In this paper, we present the feasibility assessment of an access control model that utilizes a hybrid architecture and a policy language that provides dynamic fine-grained policy enforcement in the sensors, which requires an efficient message exchange protocol called Hidra. This experimental performance assessment includes a prototype implementation, a performance evaluation model, the measurements and related discussions, which demonstrate the feasibility and adequacy of the analyzed access control model.
Feasibility Assessment of a Fine-Grained Access Control Model on Resource Constrained Sensors
Huarte, Maider; Romaña, Pedro
2018-01-01
Upcoming smart scenarios enabled by the Internet of Things (IoT) envision smart objects that provide services that can adapt to user behavior or be managed to achieve greater productivity. In such environments, smart things are inexpensive and, therefore, constrained devices. However, they are also critical components because of the importance of the information that they provide. Given this, strong security is a requirement, but not all security mechanisms in general and access control models in particular are feasible. In this paper, we present the feasibility assessment of an access control model that utilizes a hybrid architecture and a policy language that provides dynamic fine-grained policy enforcement in the sensors, which requires an efficient message exchange protocol called Hidra. This experimental performance assessment includes a prototype implementation, a performance evaluation model, the measurements and related discussions, which demonstrate the feasibility and adequacy of the analyzed access control model. PMID:29438338
Effect of a multi-layer infection control barrier on the micro-hardness of a composite resin
HWANG, In-Nam; HONG, Sung-Ok; LEE, Bin-Na; HWANG, Yun-Chan; OH, Won-Mann; CHANG, Hoon-Sang
2012-01-01
Objective The aim of this study was to evaluate the effect of multiple layers of an infection control barrier on the micro-hardness of a composite resin. Material and Methods One, two, four, and eight layers of an infection control barrier were used to cover the light guides of a high-power light emitting diode (LED) light curing unit (LCU) and a low-power halogen LCU. The composite specimens were photopolymerized with the LCUs and the barriers, and the micro-hardness of the upper and lower surfaces was measured (n=10). The hardness ratio was calculated by dividing the bottom surface hardness of the experimental groups by the irradiated surface hardness of the control groups. The data was analyzed by two-way ANOVA and Tukey's HSD test. Results The micro-hardness of the composite specimens photopolymerized with the LED LCU decreased significantly in the four- and eight-layer groups of the upper surface and in the two-, four-, and eight-layer groups of the lower surface. The hardness ratio of the composite specimens was <80% in the eight-layer group. The micro-hardness of the composite specimens photopolymerized with the halogen LCU decreased significantly in the eight-layer group of the upper surface and in the two-, four-, and eight-layer groups of the lower surface. However, the hardness ratios of all the composite specimens photopolymerized with barriers were <80%. Conclusions The two-layer infection control barrier could be used on high-power LCUs without decreasing the surface hardness of the composite resin. However, when using an infection control barrier on the low-power LCUs, attention should be paid so as not to sacrifice the polymerization efficiency. PMID:23138746
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.
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%.
Application-Defined Decentralized Access Control
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
Joint Cross-Layer Design for Wireless QoS Content Delivery
NASA Astrophysics Data System (ADS)
Chen, Jie; Lv, Tiejun; Zheng, Haitao
2005-12-01
In this paper, we propose a joint cross-layer design for wireless quality-of-service (QoS) content delivery. Central to our proposed cross-layer design is the concept of adaptation. Adaptation represents the ability to adjust protocol stacks and applications to respond to channel variations. We focus our cross-layer design especially on the application, media access control (MAC), and physical layers. The network is designed based on our proposed fast frequency-hopping orthogonal frequency division multiplex (OFDM) technique. We also propose a QoS-awareness scheduler and a power adaptation transmission scheme operating at both the base station and mobile sides. The proposed MAC scheduler coordinates the transmissions of an IP base station and mobile nodes. The scheduler also selects appropriate transmission formats and packet priorities for individual users based on current channel conditions and the users' QoS requirements. The test results show that our cross-layer design provides an excellent framework for wireless QoS content delivery.
A Protocol Layer Trust-Based Intrusion Detection Scheme for Wireless Sensor Networks
Wang, Jian; Jiang, Shuai; Fapojuwo, Abraham O.
2017-01-01
This article proposes a protocol layer trust-based intrusion detection scheme for wireless sensor networks. Unlike existing work, the trust value of a sensor node is evaluated according to the deviations of key parameters at each protocol layer considering the attacks initiated at different protocol layers will inevitably have impacts on the parameters of the corresponding protocol layers. For simplicity, the paper mainly considers three aspects of trustworthiness, namely physical layer trust, media access control layer trust and network layer trust. The per-layer trust metrics are then combined to determine the overall trust metric of a sensor node. The performance of the proposed intrusion detection mechanism is then analyzed using the t-distribution to derive analytical results of false positive and false negative probabilities. Numerical analytical results, validated by simulation results, are presented in different attack scenarios. It is shown that the proposed protocol layer trust-based intrusion detection scheme outperforms a state-of-the-art scheme in terms of detection probability and false probability, demonstrating its usefulness for detecting cross-layer attacks. PMID:28555023
A Protocol Layer Trust-Based Intrusion Detection Scheme for Wireless Sensor Networks.
Wang, Jian; Jiang, Shuai; Fapojuwo, Abraham O
2017-05-27
This article proposes a protocol layer trust-based intrusion detection scheme for wireless sensor networks. Unlike existing work, the trust value of a sensor node is evaluated according to the deviations of key parameters at each protocol layer considering the attacks initiated at different protocol layers will inevitably have impacts on the parameters of the corresponding protocol layers. For simplicity, the paper mainly considers three aspects of trustworthiness, namely physical layer trust, media access control layer trust and network layer trust. The per-layer trust metrics are then combined to determine the overall trust metric of a sensor node. The performance of the proposed intrusion detection mechanism is then analyzed using the t-distribution to derive analytical results of false positive and false negative probabilities. Numerical analytical results, validated by simulation results, are presented in different attack scenarios. It is shown that the proposed protocol layer trust-based intrusion detection scheme outperforms a state-of-the-art scheme in terms of detection probability and false probability, demonstrating its usefulness for detecting cross-layer attacks.
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.
Enhanced Multi-Modal Access to Planetary Exploration
NASA Technical Reports Server (NTRS)
Lamarra, Norm; Doyle, Richard; Wyatt, Jay
2003-01-01
Tomorrow's Interplanetary Network (IPN) will evolve from JPL's Deep-Space Network (DSN) and provide key capabilities to future investigators, such as simplified acquisition of higher-quality science at remote sites and enriched access to these sites. These capabilities could also be used to foster public interest, e.g., by making it possible for students to explore these environments personally, eventually perhaps interacting with a virtual world whose models could be populated by data obtained continuously from the IPN. Our paper looks at JPL's approach to making this evolution happen, starting from improved communications. Evolving space protocols (e.g., today's CCSDS proximity and file-transfer protocols) will provide the underpinning of such communications in the next decades, just as today's rich web was enabled by progress in Internet Protocols starting from the early 1970's (ARPAnet research). A key architectural thrust of this effort is to deploy persistent infrastructure incrementally, using a layered service model, where later higher-layer capabilities (such as adaptive science planning) are enabled by earlier lower-layer services (such as automated routing of object-based messages). In practice, there is also a mind shift needed from an engineering culture raised on point-to-point single-function communications (command uplink, telemetry downlink), to one in which assets are only indirectly accessed, via well-defined interfaces. We are aiming to foster a 'community of access' both among space assets and the humans who control them. This enables appropriate (perhaps eventually optimized) sharing of services and resources to the greater benefit of all participants. We envision such usage to be as automated in the future as using a cell phone is today - with all the steps in creating the real-time link being automated.
NASA Astrophysics Data System (ADS)
Kumar, Dayanand; Aluguri, Rakesh; Chand, Umesh; Tseng, Tseung-Yuen
2018-04-01
Ta5Si3-based conductive bridge random access memory (CBRAM) devices have been investigated to improve their resistive switching characteristics for their application in future nonvolatile memory technology. Changes in the switching characteristics by the addition of a thin Al2O3 layer of different thicknesses at the bottom electrode interface of a Ta5Si3-based CBRAM devices have been studied. The double-layer device with a 1 nm Al2O3 layer has shown improved resistive switching characteristics over the single layer one with a high on/off resistance ratio of 102, high endurance of more than 104 cycles, and good retention for more than 105 s at the temperature of 130 °C. The higher thermal conductivity of Al2O3 over Ta5Si3 has been attributed to the enhanced switching properties of the double-layer devices.
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. Copyright © 2010 Elsevier Inc. All rights reserved.
Traffic Adaptive Energy Efficient and Low Latency Medium Access Control for Wireless Sensor Networks
NASA Astrophysics Data System (ADS)
Yadav, Rajesh; Varma, Shirshu; Malaviya, N.
2008-05-01
Medium access control for wireless sensor networks has been a very active research area in the recent years. The traditional wireless medium access control protocol such as IEEE 802.11 is not suitable for the sensor network application because these are battery powered. The recharging of these sensor nodes is expensive and also not possible. The most of the literature in the medium access for the sensor network focuses on the energy efficiency. The proposed MAC protocol solves the energy inefficiency caused by idle listening, control packet overhead and overhearing taking nodes latency into consideration based on the network traffic. Simulation experiments have been performed to demonstrate the effectiveness of the proposed approach. The validation of the simulation results of the proposed MAC has been done by comparing it with the analytical model. This protocol has been simulated in Network Simulator ns-2.
NASA Astrophysics Data System (ADS)
Sayin, Mustafa; Dahint, Reiner
2017-03-01
Nanostructure formation via self-assembly processes offers a fast and cost-effective approach to generate surface patterns on large lateral scale. In particular, if the high precision of lithographic techniques is not required, a situation typical of many biotechnological and biomedical applications, it may be considered as the method of choice as it does not require any sophisticated instrumentation. However, in many cases the variety and complexity of the surface structures accessible with a single self-assembly based technique is limited. Here, we report on a new approach which combines two different self-assembly strategies, colloidal lithography and layer-by-layer deposition of polyelectrolytes, in order to significantly expand the spectrum of accessible patterns. In particular, flat and donut-like charge-patterned templates have been generated, which facilitate subsequent deposition of gold nanoparticles in dot, grid, ring, out-of-ring and circular patch structures. Potential applications are e.g. in the fields of biofunctional interfaces with well-defined lateral dimensions, optical devices with tuned properties, and controlled three-dimensional material growth.
Trust-based Access Control in Virtual Learning Community
NASA Astrophysics Data System (ADS)
Wang, Shujuan; Liu, Qingtang
The virtual learning community is an important application pattern of E-Learning. It emphasizes the cooperation of the members in the community, the members would like to share their learning resources, to exchange their experience and complete the study task together. This instructional mode has already been proved as an effective way to improve the quality and efficiency of instruction. At the present time, the virtual learning communities are mostly designed using static access control policy by which the access permission rights are authorized by the super administrator, the super administrator assigns different rights to different roles, but the virtual and social characteristics of virtual learning community make information sharing and collaboration a complex problem, the community realizes its instructional goal only if the members in it believe that others will offer the knowledge they owned and believe the knowledge others offered is well-meaning and worthy. This paper tries to constitute an effective trust mechanism, which could promise favorable interaction and lasting knowledge sharing.
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.
ERIC Educational Resources Information Center
Antony, Laljith
2016-01-01
Failing to prevent leaks of confidential and proprietary information to unauthorized users from software applications is a major challenge that companies face. Access control policies defined in software applications with access control mechanisms are unable to prevent information leaks from software applications to unauthorized users. Role-based…
Gate-Controllable Magneto-optic Kerr Effect in Layered Collinear Antiferromagnets
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sivadas, Nikhil; Okamoto, Satoshi; Xiao, Di
2016-12-23
In this paper, using symmetry arguments and a tight-binding model, we show that for layered collinear antiferromagnets, magneto-optic effects can be generated and manipulated by controlling crystal symmetries through a gate voltage. This provides a promising route for electric field manipulation of the magneto-optic effects without modifying the underlying magnetic structure. We further demonstrate the gate control of the magneto-optic Kerr effect (MOKE) in bilayer MnPSe 3 using first-principles calculations. Finally, the field-induced inversion symmetry breaking effect leads to gate-controllable MOKE, whose direction of rotation can be switched by the reversal of the gate voltage.
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.
Developing Access Control Model of Web OLAP over Trusted and Collaborative Data Warehouses
NASA Astrophysics Data System (ADS)
Fugkeaw, Somchart; Mitrpanont, Jarernsri L.; Manpanpanich, Piyawit; Juntapremjitt, Sekpon
This paper proposes the design and development of Role- based Access Control (RBAC) model for the Single Sign-On (SSO) Web-OLAP query spanning over multiple data warehouses (DWs). The model is based on PKI Authentication and Privilege Management Infrastructure (PMI); it presents a binding model of RBAC authorization based on dimension privilege specified in attribute certificate (AC) and user identification. Particularly, the way of attribute mapping between DW user authentication and privilege of dimensional access is illustrated. In our approach, we apply the multi-agent system to automate flexible and effective management of user authentication, role delegation as well as system accountability. Finally, the paper culminates in the prototype system A-COLD (Access Control of web-OLAP over multiple DWs) that incorporates the OLAP features and authentication and authorization enforcement in the multi-user and multi-data warehouse environment.
Control of excitons in multi-layer van der Waals heterostructures
DOE Office of Scientific and Technical Information (OSTI.GOV)
Calman, E. V., E-mail: ecalman@gmail.com; Dorow, C. J.; Fogler, M. M.
2016-03-07
We report an experimental study of excitons in a double quantum well van der Waals heterostructure made of atomically thin layers of MoS{sub 2} and hexagonal boron nitride. The emission of neutral and charged excitons is controlled by gate voltage, temperature, and both the helicity and the power of optical excitation.
Stacking sequence and interlayer coupling in few-layer graphene revealed by in situ imaging
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Zhu-Jun; Dong, Jichen; Cui, Yi
In the transition from graphene to graphite, the addition of each individual graphene layer modifies the electronic structure and produces a different material with unique properties. Controlled growth of few-layer graphene is therefore of fundamental interest and will provide access to materials with engineered electronic structure. Here we combine isothermal growth and etching experiments with in situ scanning electron microscopy to reveal the stacking sequence and interlayer coupling strength in few-layer graphene. The observed layer-dependent etching rates reveal the relative strength of the graphene graphene and graphene substrate interaction and the resulting mode of adlayer growth. Scanning tunnelling microscopy andmore » density functional theory calculations confirm a strong coupling between graphene edge atoms and platinum. Simulated etching confirms that etching can be viewed as reversed growth. This work demonstrates that real-time imaging under controlled atmosphere is a powerful method for designing synthesis protocols for sp2 carbon nanostructures in between graphene and graphite.« less
Stacking sequence and interlayer coupling in few-layer graphene revealed by in situ imaging
Wang, Zhu-Jun; Dong, Jichen; Cui, Yi; ...
2016-10-19
In the transition from graphene to graphite, the addition of each individual graphene layer modifies the electronic structure and produces a different material with unique properties. Controlled growth of few-layer graphene is therefore of fundamental interest and will provide access to materials with engineered electronic structure. Here we combine isothermal growth and etching experiments with in situ scanning electron microscopy to reveal the stacking sequence and interlayer coupling strength in few-layer graphene. The observed layer-dependent etching rates reveal the relative strength of the graphene graphene and graphene substrate interaction and the resulting mode of adlayer growth. Scanning tunnelling microscopy andmore » density functional theory calculations confirm a strong coupling between graphene edge atoms and platinum. Simulated etching confirms that etching can be viewed as reversed growth. This work demonstrates that real-time imaging under controlled atmosphere is a powerful method for designing synthesis protocols for sp2 carbon nanostructures in between graphene and graphite.« less
Stacking sequence and interlayer coupling in few-layer graphene revealed by in situ imaging
Wang, Zhu-Jun; Dong, Jichen; Cui, Yi; Eres, Gyula; Timpe, Olaf; Fu, Qiang; Ding, Feng; Schloegl, R.; Willinger, Marc-Georg
2016-01-01
In the transition from graphene to graphite, the addition of each individual graphene layer modifies the electronic structure and produces a different material with unique properties. Controlled growth of few-layer graphene is therefore of fundamental interest and will provide access to materials with engineered electronic structure. Here we combine isothermal growth and etching experiments with in situ scanning electron microscopy to reveal the stacking sequence and interlayer coupling strength in few-layer graphene. The observed layer-dependent etching rates reveal the relative strength of the graphene–graphene and graphene–substrate interaction and the resulting mode of adlayer growth. Scanning tunnelling microscopy and density functional theory calculations confirm a strong coupling between graphene edge atoms and platinum. Simulated etching confirms that etching can be viewed as reversed growth. This work demonstrates that real-time imaging under controlled atmosphere is a powerful method for designing synthesis protocols for sp2 carbon nanostructures in between graphene and graphite. PMID:27759024
Controlled meteorological (CMET) balloon profiling of the Arctic atmospheric boundary layer
NASA Astrophysics Data System (ADS)
Roberts, Tjarda; Hole, Lars; Voss, Paul
2017-04-01
We demonstrate profiling of the atmospheric boundary layer over Arctic ice-free and sea-ice covered regions by free-floating controllable CMET balloons. The CMET observations (temperature, humidity, wind-speed, pressure) provide in-situ meteorological datasets in very remote regions for comparison to atmospheric models. Controlled Meteorological (CMET) balloons are small airborne platforms that use reversible lift-gas compression to regulate altitude. These balloons have approximately the same payload mass as standard weather balloons but can float for many days, change altitude on command, and transmit meteorological and system data in near-real time via satellite. Five Controlled Meteorological (CMET) balloons were launched from Ny-Ålesund in Svalbard (Spitsbergen) over 5-12 May 2011 and measured vertical atmospheric profiles (temperature, humidity, wind) over coastal and remote areas to both the east and west. One notable CMET flight achieved a suite of 18 continuous soundings that probed the Arctic atmospheric boundary layer (ABL) over a period of more than 10 h. Profiles from two CMET flights are compared to model output from ECMWF Era-Interim reanalysis (ERA-I) and to a high-resolution (15 km) Arctic System Reanalysis (ASR) product. To the east of Svalbard over sea-ice, the CMET observed a stable ABL profile with a temperature inversion that was reproduced by ASR but not captured by ERA-I. In a coastal ice-free region to the west of Svalbard, the CMET observed a stable ABL with strong wind-shear. The CMET profiles document increases in ABL temperature and humidity that are broadly reproduced by both ASR and ERA-I. The ASR finds a more stably stratified ABL than observed but captured the wind shear in contrast to ERA-I. Detailed analysis of the coastal CMET-automated soundings identifies small-scale temperature and humidity variations with a low-level flow and provides an estimate of local wind fields. We show that CMET balloons are a valuable approach for
Addressing Ozone Layer Depletion
Access information on EPA's efforts to address ozone layer depletion through regulations, collaborations with stakeholders, international treaties, partnerships with the private sector, and enforcement actions under Title VI of the Clean Air Act.
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.
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…
BARTER: Behavior Profile Exchange for Behavior-Based Admission and Access Control in MANETs
NASA Astrophysics Data System (ADS)
Frias-Martinez, Vanessa; Stolfo, Salvatore J.; Keromytis, Angelos D.
Mobile Ad-hoc Networks (MANETs) are very dynamic networks with devices continuously entering and leaving the group. The highly dynamic nature of MANETs renders the manual creation and update of policies associated with the initial incorporation of devices to the MANET (admission control) as well as with anomaly detection during communications among members (access control) a very difficult task. In this paper, we present BARTER, a mechanism that automatically creates and updates admission and access control policies for MANETs based on behavior profiles. BARTER is an adaptation for fully distributed environments of our previously introduced BB-NAC mechanism for NAC technologies. Rather than relying on a centralized NAC enforcer, MANET members initially exchange their behavior profiles and compute individual local definitions of normal network behavior. During admission or access control, each member issues an individual decision based on its definition of normalcy. Individual decisions are then aggregated via a threshold cryptographic infrastructure that requires an agreement among a fixed amount of MANET members to change the status of the network. We present experimental results using content and volumetric behavior profiles computed from the ENRON dataset. In particular, we show that the mechanism achieves true rejection rates of 95% with false rejection rates of 9%.
Collision avoidance in TV white spaces: a cross-layer design approach for cognitive radio networks
NASA Astrophysics Data System (ADS)
Foukalas, Fotis; Karetsos, George T.
2015-07-01
One of the most promising applications of cognitive radio networks (CRNs) is the efficient exploitation of TV white spaces (TVWSs) for enhancing the performance of wireless networks. In this paper, we propose a cross-layer design (CLD) of carrier sense multiple access with collision avoidance (CSMA/CA) mechanism at the medium access control (MAC) layer with spectrum sensing (SpSe) at the physical layer, for identifying the occupancy status of TV bands. The proposed CLD relies on a Markov chain model with a state pair containing both the SpSe and the CSMA/CA from which we derive the collision probability and the achievable throughput. Analytical and simulation results are obtained for different collision avoidance and SpSe implementation scenarios by varying the contention window, back off stage and probability of detection. The obtained results depict the achievable throughput under different collision avoidance and SpSe implementation scenarios indicating thereby the performance of collision avoidance in TVWSs-based CRNs.
Secure Dynamic access control scheme of PHR in cloud computing.
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
Other EPA Initiatives to Protect the Ozone Layer
Access information on EPA's efforts to address ozone layer depletion through voluntary partnerships with the private sector and activities aimed at educating the public about the health effects of ozone layer depletion.
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.
NASA Astrophysics Data System (ADS)
Wang, Jie; Tang, Jing; Ding, Bing; Malgras, Victor; Chang, Zhi; Hao, Xiaodong; Wang, Ya; Dou, Hui; Zhang, Xiaogang; Yamauchi, Yusuke
2017-06-01
Although various two-dimensional (2D) nanomaterials have been explored as promising capacitive materials due to their unique layered structure, their natural restacking tendency impedes electrolyte transport and significantly restricts their practical applications. Herein, we synthesize all-carbon layer-by-layer motif architectures by introducing 2D ordered mesoporous carbons (OMC) within the interlayer space of 2D nanomaterials. As a proof of concept, MXenes are selected as 2D hosts to design 2D-2D heterostructures. Further removing the metal elements from MXenes leads to the formation of all-carbon 2D-2D heterostructures consisting of alternating layers of MXene-derived carbon (MDC) and OMC. The OMC layers intercalated with the MDC layers not only prevent restacking but also facilitate ion diffusion and electron transfer. The performance of the obtained hybrid carbons as supercapacitor electrodes demonstrates their potential for upcoming electronic devices. This method allows to overcome the restacking and blocking of 2D nanomaterials by constructing ion-accessible OMC within the 2D host material.
Evaluation of a visual layering methodology for colour coding control room displays.
Van Laar, Darren; Deshe, Ofer
2002-07-01
Eighteen people participated in an experiment in which they were asked to search for targets on control room like displays which had been produced using three different coding methods. The monochrome coding method displayed the information in black and white only, the maximally discriminable method contained colours chosen for their high perceptual discriminability, the visual layers method contained colours developed from psychological and cartographic principles which grouped information into a perceptual hierarchy. The visual layers method produced significantly faster search times than the other two coding methods which did not differ significantly from each other. Search time also differed significantly for presentation order and for the method x order interaction. There was no significant difference between the methods in the number of errors made. Participants clearly preferred the visual layers coding method. Proposals are made for the design of experiments to further test and develop the visual layers colour coding methodology.
Rural providers' access to online resources: a randomized controlled trial
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
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.
Turbulent Mixing Layer Control using Ns-DBD Plasma Actuators
NASA Astrophysics Data System (ADS)
Singh, Ashish; Little, Jesse
2016-11-01
A low speed turbulent mixing layer (Reθo =1282, U1 /U2 = 0 . 28 and U2 = 11 . 8 m / s) is subject to nanosecond pulse driven dielectric barrier discharge (ns-DBD) plasma actuation. The forcing frequency corresponds to a Strouhal number (St) of 0.032 which is the most amplified frequency based on stability theory. Flow response is studied as a function of the pulse energy, the energy input time scale (carrier frequency) and the duration of actuation (duty cycle). It is found that successful actuation requires a combination of forcing parameters. An evaluation of the forcing efficacy is achieved by examining different flow quantities such as momentum thickness, vorticity and velocity fluctuations. In accordance with past work, a dependence is found between the initial shear layer thickness and the energy coupled to the flow. More complex relationships are also revealed such as a limitation on the maximum pulse energy which yields control. Also, the pulse energy and the carrier frequency (inverse of period between successive pulses) are interdependent whereby an optimum exists between them and extreme values of either parameter is inconsonant with the control desired. These observations establish a rich and complex process behind ns-DBD plasma actuation. Air Force Office of Scientific Research (FA9550-12-1-0044).
Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers
2016-06-15
with end-functionalized polymers . First, an end-functionalized polymer with conjugated end-molecule, pyrene, is successfully employed to boron... polymers . First, an end-functionalized polymer with conjugated end-molecule, pyrenes, is successfully employed to boron nitride nanosheets (BNNS), and...AFRL-AFOSR-JP-TR-2016-0071 Controlled Interactions between Two Dimensional Layered Inorganic Nanosheets and Polymers Cheolmin Park YONSEI UNIVERSITY
Tak, Ali Zeynel Abidin; Sengul, Yıldızhan; Bilak, Şemsettin
2018-03-01
The aim of our study is to assess retinal nerve fiber layer (RNFL), the ganglion cell layer (GCL), inner-plexiform layer (IPL), and choroidal layer in migraine patients with white matter lesion (WML) or without WML, using spectral domain optical coherence tomography (OCT). To our study, 77 migraine patients who are diagnosed with migraine in accordance to the International Classification of Headache Disorders (ICHD)-3 beta and 43 healthy control are included. In accordance to cranial MRI, migraine patients are divided into two groups as those who have white matter lesions (39 patients), and those who do not have a lesion (38 patients). OCT was performed for participants. The average age of participants was comparable. The RNFL average thickness parameter in the migraine group was significantly lower than in the control group (p < 0.01). However, no significant difference was detected among those migraine patients who have WML, and those who do not have. No significant difference is detected among all groups in terms of IPL, GCL, and choroidal layer measuring scales. The proofs showing that affected retinal nerve fiber layer are increased in migraine patients. However, it is not known whether this may affect other layers of retina, or whether there is a correlation between affected retinal structures and white matter lesions. In our study, we found thinner RNFL in migraine patients when we compared with controls but IPL, GCL, and choroid layer values were similar between each patient groups and controls. Also, all parameters were similar between patients with WML and without WML. Studies in this regard are required.
Accessibility of dog populations for rabies control in Kathmandu valley, Nepal.
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
CsPbBr 3 Solar Cells: Controlled Film Growth through Layer-by-Layer Quantum Dot Deposition
Hoffman, Jacob B.; Zaiats, Gary; Wappes, Isaac; ...
2017-10-25
All inorganic cesium lead bromide (CsPbBr 3) perovskite is a more stable alternative to methylammonium lead bromide (MAPbBr 3) for designing high open-circuit voltage solar cells and display devices. Poor solubility of CsBr in organic solvents makes typical solution deposition methods difficult to adapt for constructing CsPbBr 3 devices. Our layer-by-layer methodology, which makes use of CsPbBr 3 quantum dot (QD) deposition followed by annealing, provides a convenient way to cast stable films of desired thickness. The transformation from QDs into bulk during thermal annealing arises from the resumption of nanoparticle growth and not from sintering as generally assumed. Additionally,more » a large loss of organic material during the annealing process is mainly from 1-octadecene left during the QD synthesis. Utilizing this deposition approach for perovskite photovoltaics is examined using typical planar architecture devices. Devices optimized to both QD spin-casting concentration and overall CsPbBr 3 thickness produce champion devices that reach power conversion efficiencies of 5.5% with a V oc value of 1.4 V. Finally, the layered QD deposition demonstrates a controlled perovskite film architecture for developing efficient, high open-circuit photovoltaic devices.« less
CsPbBr 3 Solar Cells: Controlled Film Growth through Layer-by-Layer Quantum Dot Deposition
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hoffman, Jacob B.; Zaiats, Gary; Wappes, Isaac
All inorganic cesium lead bromide (CsPbBr 3) perovskite is a more stable alternative to methylammonium lead bromide (MAPbBr 3) for designing high open-circuit voltage solar cells and display devices. Poor solubility of CsBr in organic solvents makes typical solution deposition methods difficult to adapt for constructing CsPbBr 3 devices. Our layer-by-layer methodology, which makes use of CsPbBr 3 quantum dot (QD) deposition followed by annealing, provides a convenient way to cast stable films of desired thickness. The transformation from QDs into bulk during thermal annealing arises from the resumption of nanoparticle growth and not from sintering as generally assumed. Additionally,more » a large loss of organic material during the annealing process is mainly from 1-octadecene left during the QD synthesis. Utilizing this deposition approach for perovskite photovoltaics is examined using typical planar architecture devices. Devices optimized to both QD spin-casting concentration and overall CsPbBr 3 thickness produce champion devices that reach power conversion efficiencies of 5.5% with a V oc value of 1.4 V. Finally, the layered QD deposition demonstrates a controlled perovskite film architecture for developing efficient, high open-circuit photovoltaic devices.« less
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.
High-efficiency exfoliation of large-area mono-layer graphene oxide with controlled dimension.
Park, Won Kyu; Yoon, Yeojoon; Song, Young Hyun; Choi, Su Yeon; Kim, Seungdu; Do, Youngjin; Lee, Junghyun; Park, Hyesung; Yoon, Dae Ho; Yang, Woo Seok
2017-11-27
In this work, we introduce a novel and facile method of exfoliating large-area, single-layer graphene oxide using a shearing stress. The shearing stress reactor consists of two concentric cylinders, where the inner cylinder rotates at controlled speed while the outer cylinder is kept stationary. We found that the formation of Taylor vortex flow with shearing stress can effectively exfoliate the graphite oxide, resulting in large-area single- or few-layer graphene oxide (GO) platelets with high yields (>90%) within 60 min of reaction time. Moreover, the lateral size of exfoliated GO sheets was readily tunable by simply controlling the rotational speed of the reactor and reaction time. Our approach for high-efficiency exfoliation of GO with controlled dimension may find its utility in numerous industrial applications including energy storage, conducting composite, electronic device, and supporting frameworks of catalyst.
DOT National Transportation Integrated Search
1974-06-01
The report synthesizes a set of satellite communications systems configurations to provide services to aircraft flying oceanic routes. These configurations are combined with access control methods to form complete systems. These systems are analyzed ...
Mapping fault-controlled volatile migration in equatorial layered deposits on Mars
NASA Astrophysics Data System (ADS)
Okubo, C. H.
2006-12-01
Research in terrestrial settings shows that clastic sedimentary deposits are productive host rocks for underground volatile reservoirs because of their high porosity and permeability. Within such reservoirs, faults play an important role in controlling pathways for volatile migration, because faults act as either barriers or conduits. Therefore faults are important volatile concentrators, which means that evidence of geochemical, hydrologic and biologic processes are commonly concentrated at these locations. Accordingly, faulted sedimentary deposits on Mars are plausible areas to search for evidence of past volatile activity and associated processes. Indeed, evidence for volatile migration through layered sedimentary deposits on Mars has been documented in detail by the Opportunity rover in Meridiani Planum. Thus evidence for past volatile- driven processes that could have occurred within the protective depths of these deposits may now exposed at the surface and more likely found around faults. Owing to the extensive distribution of layered deposits on Mars, a major challenge in looking for and investigating evidence of past volatile processes in these deposits is identifying and prioritizing study areas. Toward this end, this presentation details initial results of a multiyear project to develop quantitative maps of latent pathways for fault-controlled volatile migration through the layered sedimentary deposits on Mars. Available MOC and THEMIS imagery are used to map fault traces within equatorial layered deposits, with an emphasis on proposed regions for MSL landing sites. These fault maps define regions of interest for stereo imaging by HiRISE and identify areas to search for existing MOC stereo coverage. Stereo coverage of identified areas of interest allows for the construction of digital elevation models and ultimately extraction of fault plane and displacement vector orientations. These fault and displacement data will be fed through numerical modeling
Intermetallic layers in temperature controlled Friction Stir Welding of dissimilar Al-Cu-joints
NASA Astrophysics Data System (ADS)
Marstatt, R.; Krutzlinger, M.; Luderschmid, J.; Constanzi, G.; Mueller, J. F. J.; Haider, F.; Zaeh, M. F.
2018-06-01
Friction Stir Welding (FSW) can be performed to join dissimilar metal combinations like aluminium and copper, which is of high interest in modern production of electrical applications. The amount of intermetallic phases in the weld seam is significantly reduced compared to traditional fusion welding technologies. Because the solidus temperature is typically not reached during FSW, the growth of intermetallic phases is impeded and the intermetallic layer thicknesses typically remains on the scale of a few hundred nanometres. These layers provide a substance-to-substance bond, which is the main joining mechanism. Latest research confirms that the layer formation is most likely driven by the heat input during processing. Hence, the welding temperature is the key to achieve high quality joints. In this study, aluminium and copper sheets were welded in lap joint configuration using temperature-controlled FSW. An advanced in-tool measurement set-up was used to determine precise temperature data. Scanning electron microscopy (SEM) was used to analyse metallurgical aspects (e.g. structure and composition of the intermetallic phases) of the joints. The results show a correlation between the welding temperature and the thickness of the intermetallic layer and its structure. The temperature control significantly improved the correlation compared to previous studies. This leads to an enhanced understanding of the dominating joining mechanisms.
Precise Control of the Number of Layers of Graphene by Picosecond Laser Thinning.
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.
Precise Control of the Number of Layers of Graphene by Picosecond Laser Thinning
NASA Astrophysics Data System (ADS)
Lin, Zhe; Ye, Xiaohui; Han, Jinpeng; Chen, Qiao; Fan, Peixun; Zhang, Hongjun; Xie, Dan; Zhu, Hongwei; Zhong, Minlin
2015-06-01
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.
Provably Secure Heterogeneous Access Control Scheme for Wireless Body Area Network.
Omala, Anyembe Andrew; Mbandu, Angolo Shem; Mutiria, Kamenyi Domenic; Jin, Chunhua; Li, Fagen
2018-04-28
Wireless body area network (WBAN) provides a medium through which physiological information could be harvested and transmitted to application provider (AP) in real time. Integrating WBAN in a heterogeneous Internet of Things (IoT) ecosystem would enable an AP to monitor patients from anywhere and at anytime. However, the IoT roadmap of interconnected 'Things' is still faced with many challenges. One of the challenges in healthcare is security and privacy of streamed medical data from heterogeneously networked devices. In this paper, we first propose a heterogeneous signcryption scheme where a sender is in a certificateless cryptographic (CLC) environment while a receiver is in identity-based cryptographic (IBC) environment. We then use this scheme to design a heterogeneous access control protocol. Formal security proof for indistinguishability against adaptive chosen ciphertext attack and unforgeability against adaptive chosen message attack in random oracle model is presented. In comparison with some of the existing access control schemes, our scheme has lower computation and communication cost.
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.
DOE`s nation-wide system for access control can solve problems for the federal government
DOE Office of Scientific and Technical Information (OSTI.GOV)
Callahan, S.; Tomes, D.; Davis, G.
1996-07-01
The U.S. Department of Energy`s (DOE`s) ongoing efforts to improve its physical and personnel security systems while reducing its costs, provide a model for federal government visitor processing. Through the careful use of standardized badges, computer databases, and networks of automated access control systems, the DOE is increasing the security associated with travel throughout the DOE complex, and at the same time, eliminating paperwork, special badging, and visitor delays. The DOE is also improving badge accountability, personnel identification assurance, and access authorization timeliness and accuracy. Like the federal government, the DOE has dozens of geographically dispersed locations run by manymore » different contractors operating a wide range of security systems. The DOE has overcome these obstacles by providing data format standards, a complex-wide virtual network for security, the adoption of a standard high security system, and an open-systems-compatible link for any automated access control system. If the location`s level of security requires it, positive visitor identification is accomplished by personal identification number (PIN) and/or by biometrics. At sites with automated access control systems, this positive identification is integrated into the portals.« less
Yi, Meng; Chen, Qingkui; Xiong, Neal N
2016-11-03
This paper considers the distributed access and control problem of massive wireless sensor networks' data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival of massive service access requests at a virtual data center, this paper designs a massive sensing data access and control mechanism to improve the access efficiency of service requests and makes full use of the available resources at the data access center for the Internet of things. Firstly, this paper proposes a synergistically distributed buffer access model, which separates the information of resource and location. Secondly, the paper divides the service access requests into multiple virtual groups based on their characteristics and locations using an optimized self-organizing feature map neural network. Furthermore, this paper designs an optimal scheduling algorithm of group migration based on the combination scheme between the artificial bee colony algorithm and chaos searching theory. Finally, the experimental results demonstrate that this mechanism outperforms the existing schemes in terms of enhancing the accessibility of service requests effectively, reducing network delay, and has higher load balancing capacity and higher resource utility rate.
Yi, Meng; Chen, Qingkui; Xiong, Neal N.
2016-01-01
This paper considers the distributed access and control problem of massive wireless sensor networks’ data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival of massive service access requests at a virtual data center, this paper designs a massive sensing data access and control mechanism to improve the access efficiency of service requests and makes full use of the available resources at the data access center for the Internet of things. Firstly, this paper proposes a synergistically distributed buffer access model, which separates the information of resource and location. Secondly, the paper divides the service access requests into multiple virtual groups based on their characteristics and locations using an optimized self-organizing feature map neural network. Furthermore, this paper designs an optimal scheduling algorithm of group migration based on the combination scheme between the artificial bee colony algorithm and chaos searching theory. Finally, the experimental results demonstrate that this mechanism outperforms the existing schemes in terms of enhancing the accessibility of service requests effectively, reducing network delay, and has higher load balancing capacity and higher resource utility rate. PMID:27827878
Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide
DOE Office of Scientific and Technical Information (OSTI.GOV)
Gao, Xiaorui, E-mail: gxr_1320@sina.com; School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189; Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA
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 amore » 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.« less
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)
Controlling the layer localization of gapless states in bilayer graphene with a gate voltage
NASA Astrophysics Data System (ADS)
Jaskólski, W.; Pelc, M.; Bryant, Garnett W.; Chico, Leonor; Ayuela, A.
2018-04-01
Experiments in gated bilayer graphene with stacking domain walls present topological gapless states protected by no-valley mixing. Here we research these states under gate voltages using atomistic models, which allow us to elucidate their origin. We find that the gate potential controls the layer localization of the two states, which switches non-trivially between layers depending on the applied gate voltage magnitude. We also show how these bilayer gapless states arise from bands of single-layer graphene by analyzing the formation of carbon bonds between layers. Based on this analysis we provide a model Hamiltonian with analytical solutions, which explains the layer localization as a function of the ratio between the applied potential and interlayer hopping. Our results open a route for the manipulation of gapless states in electronic devices, analogous to the proposed writing and reading memories in topological insulators.
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
Providing Internet Access to High-Resolution Lunar Images
NASA Technical Reports Server (NTRS)
Plesea, Lucian
2008-01-01
The OnMoon server is a computer program that provides Internet access to high-resolution Lunar images, maps, and elevation data, all suitable for use in geographical information system (GIS) software for generating images, maps, and computational models of the Moon. The OnMoon server implements the Open Geospatial Consortium (OGC) Web Map Service (WMS) server protocol and supports Moon-specific extensions. Unlike other Internet map servers that provide Lunar data using an Earth coordinate system, the OnMoon server supports encoding of data in Moon-specific coordinate systems. The OnMoon server offers access to most of the available high-resolution Lunar image and elevation data. This server can generate image and map files in the tagged image file format (TIFF) or the Joint Photographic Experts Group (JPEG), 8- or 16-bit Portable Network Graphics (PNG), or Keyhole Markup Language (KML) format. Image control is provided by use of the OGC Style Layer Descriptor (SLD) protocol. Full-precision spectral arithmetic processing is also available, by use of a custom SLD extension. This server can dynamically add shaded relief based on the Lunar elevation to any image layer. This server also implements tiled WMS protocol and super-overlay KML for high-performance client application programs.
NASA Astrophysics Data System (ADS)
Tanaka, Yukinobu; Ogata, Takeshi; Imagawa, Seiji
2015-09-01
We developed a decoupled direct tracking control system for multilayer optical disk that uses a separate guide layer. Data marks are recorded on a recording layer immediately above the guide layer by using two spatially separated spots with different wavelengths. Accurate data mark recording requires that the relative positions of the corresponding spots on the recording layer and guide layer are maintained. However, a disk tilt can shift their relative positions and cause previously recorded data marks to be overwritten. Additionally, a two-input/two-output control system is susceptible to mutual interference phenomenon between the two outputs, which can destabilize tracking control. A tracking control system based on use of data marks previously recorded as a virtual track has been developed that prevents spot shifting and mutual interference even if the disk tilt reaches 0.7°, thereby preventing overwriting.
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.
An Internet of Things Example: Classrooms Access Control over Near Field Communication
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
An internet of things example: classrooms access control over near field communication.
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.
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…
Design of an Efficient CAC for a Broadband DVB-S/DVB-RCS Satellite Access Network
NASA Astrophysics Data System (ADS)
Inzerilli, Tiziano; Montozzi, Simone
2003-07-01
This paper deals with efficient utilization of network resources in an advanced broadband satellite access system. It proposes a technique for admission control of IP streams with guaranteed QoS which does not interfere with the particular BoD (Bandwidth on Demand) algorithm that handles access to uplink bandwidth, an essential part of a DVB- RCS architecture. This feature of the admission control greatly simplify its integration in the satellite network. The purpose of this admission control algorithm in particular is to suitably and dynamically configure the overall traffic control parameters, in the access terminal of the user and service segment, with a simple approach which does not introduces limitations and/or constraints to the BoD algorithm. Performance of the proposed algorithm is evaluated thorugh Opnet simulations using an ad-hoc platform modeling DVB-based satellite access.The results presented in this paper were obtained within SATIP6 project, which is sponsored within the 5th EU Research Programme, IST. The aims of the project are to evaluate and demonstrate key issues of the integration of satellite-based access networks into the Internet in order to support multimedia services over wide areas. The satellite link layer is based on DVB-S on the forward link and DVB-RCS on the return link. Adaptation and optimization of the DVB-RCS access standard in order to support QoS provision are central issues of the project. They are handled through an integration of Connection Admission Control (CAC), Traffic Shaping and Policing techniques.
Cross-Dependency Inference in Multi-Layered Networks: A Collaborative Filtering Perspective.
Chen, Chen; Tong, Hanghang; Xie, Lei; Ying, Lei; He, Qing
2017-08-01
The increasingly connected world has catalyzed the fusion of networks from different domains, which facilitates the emergence of a new network model-multi-layered networks. Examples of such kind of network systems include critical infrastructure networks, biological systems, organization-level collaborations, cross-platform e-commerce, and so forth. One crucial structure that distances multi-layered network from other network models is its cross-layer dependency, which describes the associations between the nodes from different layers. Needless to say, the cross-layer dependency in the network plays an essential role in many data mining applications like system robustness analysis and complex network control. However, it remains a daunting task to know the exact dependency relationships due to noise, limited accessibility, and so forth. In this article, we tackle the cross-layer dependency inference problem by modeling it as a collective collaborative filtering problem. Based on this idea, we propose an effective algorithm Fascinate that can reveal unobserved dependencies with linear complexity. Moreover, we derive Fascinate-ZERO, an online variant of Fascinate that can respond to a newly added node timely by checking its neighborhood dependencies. We perform extensive evaluations on real datasets to substantiate the superiority of our proposed approaches.
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.
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)
NASA Astrophysics Data System (ADS)
Sathyanadh, A.; Karipot, A.; Prabhakaran, T.
2016-12-01
Planetary boundary layer (PBL) height and its controlling factors undergo large variations at different spatio-temporal scales over land regions. In the present study, Modern Era Retrospective analysis for Research and Applications (MERRA) data products are used to investigate variations of PBL height and its controls in relation to different phases of Indian monsoon. MERRA PBL height validations carried out against those estimated from radiosonde and Global Positioning System Radio Occultation atmospheric profiles revealed fairly good agreement. Different PBL patterns are identified in terms of maximum height, its time of occurrence and growth rate, and they vary with respect to geographical locations, terrain characteristics and monsoon circulation. The pre-monsoon boundary layers are the deepest over the region, often exceeding 4 km and grow at a rate of approximately 400 m hr-1. Large nocturnal BL depths, possibly related to weakly convective residual layers, are another feature noted during dry conditions. Monsoon BLs are generally shallower, except where rainfall is scanty. The break-monsoon periods have slightly deeper BLs than the active monsoon phase. The controlling factors for the observed boundary layer behaviour are investigated using supplementary MERRA datasets. Evaporative fraction is found to have dominant control on the PBL height varying with seasons and regions. The characteristics and controls of wet and dry boundary layer regimes over inland and coastal locations are different. The fractional diffusion (ratio of non-local and total diffusion) coefficient analyses indicated that enhanced entrainment during monsoon contributes to reduction in PBLH unlike in the dry period. The relationship between controls and PBLH are better defined over inland than coastal regions. The wavelet cross spectral analysis revealed temporal variations in dominant contributions from the controlling factors at different periodicities during the course of the year.
Active control of panel vibrations induced by boundary-layer flow
NASA Technical Reports Server (NTRS)
Chow, Pao-Liu
1991-01-01
Some problems in active control of panel vibration excited by a boundary layer flow over a flat plate are studied. In the first phase of the study, the optimal control problem of vibrating elastic panel induced by a fluid dynamical loading was studied. For a simply supported rectangular plate, the vibration control problem can be analyzed by a modal analysis. The control objective is to minimize the total cost functional, which is the sum of a vibrational energy and the control cost. By means of the modal expansion, the dynamical equation for the plate and the cost functional are reduced to a system of ordinary differential equations and the cost functions for the modes. For the linear elastic plate, the modes become uncoupled. The control of each modal amplitude reduces to the so-called linear regulator problem in control theory. Such problems can then be solved by the method of adjoint state. The optimality system of equations was solved numerically by a shooting method. The results are summarized.
Why build limited access highways?.
DOT National Transportation Integrated Search
1991-01-01
This report first explains what a limited access highway is, then describes the benefits and advantages of limited access highways. As compared with highways with no control of access, limited access highways (especially those with full control) have...
Huang, Qinlong; Yang, Yixian; Shi, Yuxiang
2018-02-24
With the growing number of vehicles and popularity of various services in vehicular cloud computing (VCC), message exchanging among vehicles under traffic conditions and in emergency situations is one of the most pressing demands, and has attracted significant attention. However, it is an important challenge to authenticate the legitimate sources of broadcast messages and achieve fine-grained message access control. In this work, we propose SmartVeh, a secure and efficient message access control and authentication scheme in VCC. A hierarchical, attribute-based encryption technique is utilized to achieve fine-grained and flexible message sharing, which ensures that vehicles whose persistent or dynamic attributes satisfy the access policies can access the broadcast message with equipped on-board units (OBUs). Message authentication is enforced by integrating an attribute-based signature, which achieves message authentication and maintains the anonymity of the vehicles. In order to reduce the computations of the OBUs in the vehicles, we outsource the heavy computations of encryption, decryption and signing to a cloud server and road-side units. The theoretical analysis and simulation results reveal that our secure and efficient scheme is suitable for VCC.
Yang, Yixian; Shi, Yuxiang
2018-01-01
With the growing number of vehicles and popularity of various services in vehicular cloud computing (VCC), message exchanging among vehicles under traffic conditions and in emergency situations is one of the most pressing demands, and has attracted significant attention. However, it is an important challenge to authenticate the legitimate sources of broadcast messages and achieve fine-grained message access control. In this work, we propose SmartVeh, a secure and efficient message access control and authentication scheme in VCC. A hierarchical, attribute-based encryption technique is utilized to achieve fine-grained and flexible message sharing, which ensures that vehicles whose persistent or dynamic attributes satisfy the access policies can access the broadcast message with equipped on-board units (OBUs). Message authentication is enforced by integrating an attribute-based signature, which achieves message authentication and maintains the anonymity of the vehicles. In order to reduce the computations of the OBUs in the vehicles, we outsource the heavy computations of encryption, decryption and signing to a cloud server and road-side units. The theoretical analysis and simulation results reveal that our secure and efficient scheme is suitable for VCC. PMID:29495269
The assessment of exploitation process of power for access control system
NASA Astrophysics Data System (ADS)
Wiśnios, Michał; Paś, Jacek
2017-10-01
The safety of public utility facilities is a function not only of effectiveness of the electronic safety systems, used for protection of property and persons, but it also depends on the proper functioning of their power supply systems. The authors of the research paper analysed the power supply systems, which are used in buildings for the access control system that is integrated with the closed-circuit TV. The Access Control System is a set of electronic, electromechanical and electrical devices and the computer software controlling the operation of the above-mentioned elements, which is aimed at identification of people, vehicles allowed to cross the boundary of the reserved area, to prevent from crossing the reserved area and to generate the alarm signal informing about the attempt of crossing by an unauthorised entity. The industrial electricity with appropriate technical parameters is a basis of proper functioning of safety systems. Only the electricity supply to the systems is not equivalent to the operation continuity provision. In practice, redundant power supply systems are used. In the carried out reliability analysis of the power supply system, various power circuits of the system were taken into account. The reliability and operation requirements for this type of system were also included.
NASA Technical Reports Server (NTRS)
Maestrello, L.; Grosveld, F. W.
1991-01-01
The experiment is aimed at controlling the boundary layer transition location and the plate vibration when excited by a flow and an upstream sound source. Sound has been found to affect the flow at the leading edge and the response of a flexible plate in a boundary layer. Because the sound induces early transition, the panel vibration is acoustically coupled to the turbulent boundary layer by the upstream radiation. Localized surface heating at the leading edge delays the transition location downstream of the flexible plate. The response of the plate excited by a turbulent boundary layer (without sound) shows that the plate is forced to vibrate at different frequencies and with different amplitudes as the flow velocity changes indicating that the plate is driven by the convective waves of the boundary layer. The acoustic disturbances induced by the upstream sound dominate the response of the plate when the boundary layer is either turbulent or laminar. Active vibration control was used to reduce the sound induced displacement amplitude of the plate.
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.
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.
Analyzing the effect of routing protocols on media access control protocols in radio networks
DOE Office of Scientific and Technical Information (OSTI.GOV)
Barrett, C. L.; Drozda, M.; Marathe, A.
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)more » 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.« less
NASA Astrophysics Data System (ADS)
Yuan, Peng; Zhang, Ning; Zhang, Dan; Liu, Tao; Chen, Limiao; Ma, Renzhi; Qiu, Guanzhou; Liu, Xiaohe
2016-01-01
A facile solvothermal method is developed for synthesizing layered Co-Ni hydroxide hierarchical structures by using hexamethylenetetramine (HMT) as alkaline reagent. The electrochemical measurements reveal that the specific capacitances of layered bimetallic (Co-Ni) hydroxides are generally superior to those of layered monometallic (Co, Ni) hydroxides. The as-prepared Co0.5Ni0.5 hydroxide hierarchical structures possesses the highest specific capacitance of 1767 F g-1 at a galvanic current density of 1 A g-1 and an outstanding specific capacitance retention of 87% after 1000 cycles. In comparison with the dispersed nanosheets of Co-Ni hydroxide, layered hydroxide hierarchical structures show much superior electrochemical performance. This study provides a promising method to construct hierarchical structures with controllable transition-metal compositions for enhancing the electrochemical performance in hybrid supercapacitors.
NASA Astrophysics Data System (ADS)
Mokhtar, N. F. M.; Khalid, I. K.; Siri, Z.; Ibrahim, Z. B.; Gani, S. S. A.
2017-10-01
The influences of feedback control and internal heat source on the onset of Rayleigh-Bénard convection in a horizontal nanofluid layer is studied analytically due to Soret and Dufour parameters. The confining boundaries of the nanofluid layer (bottom boundary-top boundary) are assumed to be free-free, rigid-free, and rigid-rigid, with a source of heat from below. Linear stability theory is applied, and the eigenvalue solution is obtained numerically using the Galerkin technique. Focusing on the stationary convection, it is shown that there is a positive thermal resistance in the presence of feedback control on the onset of double-diffusive convection, while there is a positive thermal efficiency in the existence of internal heat generation. The possibilities of suppress or augment of the Rayleigh-Bénard convection in a nanofluid layer are also discussed in detail.
21 CFR 1311.125 - Requirements for establishing logical access control-Individual practitioner.
Code of Federal Regulations, 2010 CFR
2010-04-01
... substance prescriptions and who has obtained a two-factor authentication credential as provided in § 1311... his two-factor authentication credential to satisfy the logical access controls. The second individual... authentication factor required by the two-factor authentication protocol is lost, stolen, or compromised. Such...
BIOPACK: the ground controlled late access biological research facility.
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.
Highly scalable, closed-loop synthesis of drug-loaded, layer-by-layer nanoparticles.
Correa, Santiago; Choi, Ki Young; Dreaden, Erik C; Renggli, Kasper; Shi, Aria; Gu, Li; Shopsowitz, Kevin E; Quadir, Mohiuddin A; Ben-Akiva, Elana; Hammond, Paula T
2016-02-16
Layer-by-layer (LbL) self-assembly is a versatile technique from which multicomponent and stimuli-responsive nanoscale drug carriers can be constructed. Despite the benefits of LbL assembly, the conventional synthetic approach for fabricating LbL nanoparticles requires numerous purification steps that limit scale, yield, efficiency, and potential for clinical translation. In this report, we describe a generalizable method for increasing throughput with LbL assembly by using highly scalable, closed-loop diafiltration to manage intermediate purification steps. This method facilitates highly controlled fabrication of diverse nanoscale LbL formulations smaller than 150 nm composed from solid-polymer, mesoporous silica, and liposomal vesicles. The technique allows for the deposition of a broad range of polyelectrolytes that included native polysaccharides, linear polypeptides, and synthetic polymers. We also explore the cytotoxicity, shelf life and long-term storage of LbL nanoparticles produced using this approach. We find that LbL coated systems can be reliably and rapidly produced: specifically, LbL-modified liposomes could be lyophilized, stored at room temperature, and reconstituted without compromising drug encapsulation or particle stability, thereby facilitating large scale applications. Overall, this report describes an accessible approach that significantly improves the throughput of nanoscale LbL drug-carriers that show low toxicity and are amenable to clinically relevant storage conditions.
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.
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.
A Big Data Platform for Storing, Accessing, Mining and Learning Geospatial Data
NASA Astrophysics Data System (ADS)
Yang, C. P.; Bambacus, M.; Duffy, D.; Little, M. M.
2017-12-01
Big Data is becoming a norm in geoscience domains. A platform that is capable to effiently manage, access, analyze, mine, and learn the big data for new information and knowledge is desired. This paper introduces our latest effort on developing such a platform based on our past years' experiences on cloud and high performance computing, analyzing big data, comparing big data containers, and mining big geospatial data for new information. The platform includes four layers: a) the bottom layer includes a computing infrastructure with proper network, computer, and storage systems; b) the 2nd layer is a cloud computing layer based on virtualization to provide on demand computing services for upper layers; c) the 3rd layer is big data containers that are customized for dealing with different types of data and functionalities; d) the 4th layer is a big data presentation layer that supports the effient management, access, analyses, mining and learning of big geospatial data.
IP access networks with QoS support
NASA Astrophysics Data System (ADS)
Sargento, Susana; Valadas, Rui J. M. T.; Goncalves, Jorge; Sousa, Henrique
2001-07-01
The increasing demand of new services and applications is pushing for drastic changes on the design of access networks targeted mainly for residential and SOHO users. Future access networks will provide full service integration (including multimedia), resource sharing at the packet level and QoS support. It is expected that using IP as the base technology, the ideal plug-and-play scenario, where the management actions of the access network operator are kept to a minimum, will be achieved easily. This paper proposes an architecture for access networks based on layer 2 or layer 3 multiplexers that allows a number of simplifications in the network elements and protocols (e.g. in the routing and addressing functions). We discuss two possible steps in the evolution of access networks towards a more efficient support of IP based services. The first one still provides no QoS support and was designed with the goal of reusing as much as possible current technologies; it is based on tunneling to transport PPP sessions. The second one introduces QoS support through the use of emerging technologies and protocols. We illustrate the different phases of a multimedia Internet access session, when using SIP for session initiation, COPS for the management of QoS policies including the AAA functions and RSVP for resource reservation.
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.
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.
Inner layer-embedded contact lenses for pH-triggered controlled ocular drug delivery.
Zhu, Qiang; Liu, Chang; Sun, Zheng; Zhang, Xiaofei; Liang, Ning; Mao, Shirui
2018-07-01
Contact lenses (CLs) are ideally suited for controlled ocular drug delivery, but are limited by short release duration, poor storage stability and low drug loading. In this study, we present a novel inner layer-embedded contact lens capable of pH-triggered extended ocular drug delivery with good storage stability. Blend film of ethyl cellulose and Eudragit S100 was used as the inner layer, while pHEMA hydrogel was used as outer layer to fabricate inner layer-embedded contact lens. Using diclofenac sodium(DS) as a drug model, influence of polymer ratio in the blend film, EC viscosity, drug/polymer ratio, inner layer thickness and outlayer thickness of pHEMA hydrogel on drug release behavior was studied and optimized for daily use. The pH-triggered drug eluting pattern enables the inner layer-embedded contact lens being stored in phosphate buffer solution pH 6.8 with ignorable drug loss and negligible changes in drug release pattern. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 24 h in tear fluid, indicating significant improvement in drug corneal residence time. A level A IVIVC was established between in vitro drug release and in vivo drug concentration in tear fluid. In conclusion, this inner layer embedded contact lens design could be used as a platform for extended ocular drug delivery with translational potential for both anterior and posterior ocular diseases therapy. Copyright © 2018 Elsevier B.V. All rights reserved.
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…
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 individual...
Scott, Angela Bullanday; Singh, Mini; Toribio, Jenny-Ann; Hernandez-Jover, Marta; Barnes, Belinda; Glass, Kathryn; Moloney, Barbara; Lee, Amanda; Groves, Peter
2017-01-01
There are few published studies describing the unique management practices, farm design and housing characteristics of commercial meat chicken and layer farms in Australia. In particular, there has been a large expansion of free range poultry production in Australia in recent years, but limited information about this enterprise exists. This study aimed to describe features of Australian commercial chicken farms, with particular interest in free range farms, by conducting on-farm interviews of 25 free range layer farms, nine cage layer farms, nine barn layer farms, six free range meat chicken farms and 15 barn meat chicken farms in the Sydney basin bioregion and South East Queensland. Comparisons between the different enterprises (cage, barn and free range) were explored, including stocking densities, depopulation procedures, environmental control methods and sources of information for farmers. Additional information collected for free range farms include range size, range characteristics and range access. The median number of chickens per shed was greatest in free range meat chicken farms (31,058), followed by barn meat chicken (20,817), free range layer (10,713), barn layer (9,300) and cage layer farms (9,000). Sheds had cooling pads and tunnel ventilation in just over half of both barn and free range meat chicken farms (53%, n = 8) and was least common in free range layer farms (16%, n = 4). Range access in free range meat chicken farms was from sunrise to dark in the majority (93%, n = 14) of free range meat chicken farms. Over half of free range layer farms (56%, n = 14) granted range access at a set time each morning; most commonly between 9:00 to 10.00am (86%, n = 12), and chickens were placed back inside sheds when it was dusk.
Singh, Mini; Toribio, Jenny-Ann; Hernandez-Jover, Marta; Barnes, Belinda; Glass, Kathryn; Moloney, Barbara; Lee, Amanda; Groves, Peter
2017-01-01
There are few published studies describing the unique management practices, farm design and housing characteristics of commercial meat chicken and layer farms in Australia. In particular, there has been a large expansion of free range poultry production in Australia in recent years, but limited information about this enterprise exists. This study aimed to describe features of Australian commercial chicken farms, with particular interest in free range farms, by conducting on-farm interviews of 25 free range layer farms, nine cage layer farms, nine barn layer farms, six free range meat chicken farms and 15 barn meat chicken farms in the Sydney basin bioregion and South East Queensland. Comparisons between the different enterprises (cage, barn and free range) were explored, including stocking densities, depopulation procedures, environmental control methods and sources of information for farmers. Additional information collected for free range farms include range size, range characteristics and range access. The median number of chickens per shed was greatest in free range meat chicken farms (31,058), followed by barn meat chicken (20,817), free range layer (10,713), barn layer (9,300) and cage layer farms (9,000). Sheds had cooling pads and tunnel ventilation in just over half of both barn and free range meat chicken farms (53%, n = 8) and was least common in free range layer farms (16%, n = 4). Range access in free range meat chicken farms was from sunrise to dark in the majority (93%, n = 14) of free range meat chicken farms. Over half of free range layer farms (56%, n = 14) granted range access at a set time each morning; most commonly between 9:00 to 10.00am (86%, n = 12), and chickens were placed back inside sheds when it was dusk. PMID:29166389
Remote direct memory access over datagrams
Grant, Ryan Eric; Rashti, Mohammad Javad; Balaji, Pavan; Afsahi, Ahmad
2014-12-02
A communication stack for providing remote direct memory access (RDMA) over a datagram network is disclosed. The communication stack has a user level interface configured to accept datagram related input and communicate with an RDMA enabled network interface card (NIC) via an NIC driver. The communication stack also has an RDMA protocol layer configured to supply one or more data transfer primitives for the datagram related input of the user level. The communication stack further has a direct data placement (DDP) layer configured to transfer the datagram related input from a user storage to a transport layer based on the one or more data transfer primitives by way of a lower layer protocol (LLP) over the datagram network.
A Secure and Verifiable Outsourced Access Control Scheme in Fog-Cloud Computing.
Fan, Kai; Wang, Junxiong; Wang, Xin; Li, Hui; Yang, Yintang
2017-07-24
With the rapid development of big data and Internet of things (IOT), the number of networking devices and data volume are increasing dramatically. Fog computing, which extends cloud computing to the edge of the network can effectively solve the bottleneck problems of data transmission and data storage. However, security and privacy challenges are also arising in the fog-cloud computing environment. Ciphertext-policy attribute-based encryption (CP-ABE) can be adopted to realize data access control in fog-cloud computing systems. In this paper, we propose a verifiable outsourced multi-authority access control scheme, named VO-MAACS. In our construction, most encryption and decryption computations are outsourced to fog devices and the computation results can be verified by using our verification method. Meanwhile, to address the revocation issue, we design an efficient user and attribute revocation method for it. Finally, analysis and simulation results show that our scheme is both secure and highly efficient.
A Secure and Verifiable Outsourced Access Control Scheme in Fog-Cloud Computing
Fan, Kai; Wang, Junxiong; Wang, Xin; Li, Hui; Yang, Yintang
2017-01-01
With the rapid development of big data and Internet of things (IOT), the number of networking devices and data volume are increasing dramatically. Fog computing, which extends cloud computing to the edge of the network can effectively solve the bottleneck problems of data transmission and data storage. However, security and privacy challenges are also arising in the fog-cloud computing environment. Ciphertext-policy attribute-based encryption (CP-ABE) can be adopted to realize data access control in fog-cloud computing systems. In this paper, we propose a verifiable outsourced multi-authority access control scheme, named VO-MAACS. In our construction, most encryption and decryption computations are outsourced to fog devices and the computation results can be verified by using our verification method. Meanwhile, to address the revocation issue, we design an efficient user and attribute revocation method for it. Finally, analysis and simulation results show that our scheme is both secure and highly efficient. PMID:28737733
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.
Constraints of nonresponding flows based on cross layers in the networks
NASA Astrophysics Data System (ADS)
Zhou, Zhi-Chao; Xiao, Yang; Wang, Dong
2016-02-01
In the active queue management (AQM) scheme, core routers cannot manage and constrain user datagram protocol (UDP) data flows by the sliding window control mechanism in the transport layer due to the nonresponsive nature of such traffic flows. However, the UDP traffics occupy a large part of the network service nowadays which brings a great challenge to the stability of the more and more complex networks. To solve the uncontrollable problem, this paper proposes a cross layers random early detection (CLRED) scheme, which can control the nonresponding UDP-like flows rate effectively when congestion occurs in the access point (AP). The CLRED makes use of the MAC frame acknowledgement (ACK) transmitting congestion information to the sources nodes and utilizes the back-off windows of the MAC layer throttling data rate. Consequently, the UDP-like flows data rate can be restrained timely by the sources nodes in order to alleviate congestion in the complex networks. The proposed CLRED can constrain the nonresponsive flows availably and make the communication expedite, so that the network can sustain stable. The simulation results of network simulator-2 (NS2) verify the proposed CLRED scheme.
NASA Astrophysics Data System (ADS)
Lin, Guofen; Hong, Hanshu; Xia, Yunhao; Sun, Zhixin
2017-10-01
Attribute-based encryption (ABE) is an interesting cryptographic technique for flexible cloud data sharing access control. However, some open challenges hinder its practical application. In previous schemes, all attributes are considered as in the same status while they are not in most of practical scenarios. Meanwhile, the size of access policy increases dramatically with the raise of its expressiveness complexity. In addition, current research hardly notices that mobile front-end devices, such as smartphones, are poor in computational performance while too much bilinear pairing computation is needed for ABE. In this paper, we propose a key-policy weighted attribute-based encryption without bilinear pairing computation (KP-WABE-WB) for secure cloud data sharing access control. A simple weighted mechanism is presented to describe different importance of each attribute. We introduce a novel construction of ABE without executing any bilinear pairing computation. Compared to previous schemes, our scheme has a better performance in expressiveness of access policy and computational efficiency.
The SOOS Data Portal, providing access to Southern Oceans data
NASA Astrophysics Data System (ADS)
Proctor, Roger; Finney, Kim; Blain, Peter; Taylor, Fiona; Newman, Louise; Meredith, Mike; Schofield, Oscar
2013-04-01
The Southern Ocean Observing System (SOOS) is an international initiative to enhance, coordinate and expand the strategic observations of the Southern Oceans that are required to address key scientific and societal challenges. A key component of SOOS will be the creation and maintenance of a Southern Ocean Data Portal to provide improved access to historical and ongoing data (Schofield et al., 2012, Eos, Vol. 93, No. 26, pp 241-243). The scale of this effort will require strong leveraging of existing data centres, new cyberinfrastructure development efforts, and defined data collection, quality control, and archiving procedures across the international community. The task of assembling the SOOS data portal is assigned to the SOOS Data Management Sub-Committee. The information infrastructure chosen for the SOOS data portal is based on the Australian Ocean Data Network (AODN, http://portal.aodn.org.au). The AODN infrastructure is built on open-source tools and the use of international standards ensures efficiency of data exchange and interoperability between contributing systems. OGC standard web services protocols are used for serving of data via the internet. These include Web Map Service (WMS) for visualisation, Web Feature Service (WFS) for data download, and Catalogue Service for Web (CSW) for catalogue exchange. The portal offers a number of tools to access and visualize data: - a Search link to the metadata catalogue enables search and discovery by simple text search, by geographic area, temporal extent, keyword, parameter, organisation, or by any combination of these, allowing users to gain access to further information and/or the data for download. Also, searches can be restricted to items which have either data to download, or attached map layers, or both - a Map interface for discovery and display of data, with the ability to change the style and opacity of layers, add additional data layers via OGC Web Map Services, view animated timeseries datastreams
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.)
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.
Study of flow control by localized volume heating in hypersonic boundary layers
NASA Astrophysics Data System (ADS)
Keller, M. A.; Kloker, M. J.; Kirilovskiy, S. V.; Polivanov, P. A.; Sidorenko, A. A.; Maslov, A. A.
2014-12-01
Boundary-layer flow control is a prerequisite for a safe and efficient operation of future hypersonic transport systems. Here, the influence of an electric discharge—modeled by a heat-source term in the energy equation—on laminar boundary-layer flows over a flat plate with zero pressure gradient at Mach 3, 5, and 7 is investigated numerically. The aim was to appraise the potential of electro-gasdynamic devices for an application as turbulence generators in the super- and hypersonic flow regime. The results with localized heat-source elements in boundary layers are compared to cases with roughness elements serving as classical passive trips. The numerical simulations are performed using the commercial code ANSYS FLUENT (by ITAM) and the high-order finite-difference DNS code NS3D (by IAG), the latter allowing for the detailed analysis of laminar flow instability. For the investigated setups with steady heating, transition to turbulence is not observed, due to the Reynolds-number lowering effect of heating.
NASA Technical Reports Server (NTRS)
Cook, Woodrow L; Anderson, Seth B; Cooper, George E
1958-01-01
A wind-tunnel investigation was made to determine the effects on the aerodynamic characteristics of a 35 degree swept-wing airplane of applying area-suction boundary-layer control to the trailing-edge flaps. Flight tests of a similar airplane were then conducted to determine the effect of boundary-layer control in the handling qualities and operation of the airplane, particularly during landing. The wind-tunnel and flight tests indicated that area suction applied to the trailing-edge flaps produced significant increases in flap lift increment. Although the flap boundary-layer control reduced the stall speed only slightly, a reduction in minimum comfortable approach speed of about 12 knots was obtained.
NASA Astrophysics Data System (ADS)
Chuang, Kai-Chi; Chung, Hao-Tung; Chu, Chi-Yan; Luo, Jun-Dao; Li, Wei-Shuo; Li, Yi-Shao; Cheng, Huang-Chung
2018-06-01
An AlO x layer was deposited on HfO x , and bilayered dielectric films were found to confine the formation locations of conductive filaments (CFs) during the forming process and then improve device-to-device uniformity. In addition, the Ti interposing layer was also adopted to facilitate the formation of oxygen vacancies. As a result, the resistive random access memory (RRAM) device with TiN/Ti/AlO x (1 nm)/HfO x (6 nm)/TiN stack layers demonstrated excellent device-to-device uniformity although it achieved slightly larger resistive switching characteristics, which were forming voltage (V Forming) of 2.08 V, set voltage (V Set) of 1.96 V, and reset voltage (V Reset) of ‑1.02 V, than the device with TiN/Ti/HfO x (6 nm)/TiN stack layers. However, the device with a thicker 2-nm-thick AlO x layer showed worse uniformity than the 1-nm-thick one. It was attributed to the increased oxygen atomic percentage in the bilayered dielectric films of the 2-nm-thick one. The difference in oxygen content showed that there would be less oxygen vacancies to form CFs. Therefore, the random growth of CFs would become severe and the device-to-device uniformity would degrade.
Ni-base superalloy powder-processed porous layer for gas cooling in extreme environments
White, Emma M. H.; Heidloff, Andrew J.; Byrd, David J.; ...
2016-05-26
Extreme high temperature conditions demand novel solutions for hot gas filters and coolant access architectures, i.e., porous layers on exposed components. These high temperatures, for example in current turbine engines, are at or exceeding current material limits for high temperature oxidation/corrosion, creep resistance, and, even, melting temperature. Thus novel blade designs allowing greater heat removal are required to maintain airfoil temperatures below melting and/ or rapid creep deformation limits. Gas atomized Ni-base superalloy powders were partially sintered into porous layers to allow full-surface, transpirational cooling of the surface of airfoils. Furthermore, these powder-processed porous layers were fully characterized for surface,more » morphology, cross-sectional microstructure, and mechanical strength characteristics. A sintering model based on pure Ni surface diffusion correlated well with the experimental results and allowed reasonable control over the partial sintering process to obtain a specified level of porosity within the porous layer.« less
Ni-base superalloy powder-processed porous layer for gas cooling in extreme environments
DOE Office of Scientific and Technical Information (OSTI.GOV)
White, Emma M. H.; Heidloff, Andrew J.; Byrd, David J.
Extreme high temperature conditions demand novel solutions for hot gas filters and coolant access architectures, i.e., porous layers on exposed components. These high temperatures, for example in current turbine engines, are at or exceeding current material limits for high temperature oxidation/corrosion, creep resistance, and, even, melting temperature. Thus novel blade designs allowing greater heat removal are required to maintain airfoil temperatures below melting and/ or rapid creep deformation limits. Gas atomized Ni-base superalloy powders were partially sintered into porous layers to allow full-surface, transpirational cooling of the surface of airfoils. Furthermore, these powder-processed porous layers were fully characterized for surface,more » morphology, cross-sectional microstructure, and mechanical strength characteristics. A sintering model based on pure Ni surface diffusion correlated well with the experimental results and allowed reasonable control over the partial sintering process to obtain a specified level of porosity within the porous layer.« less
Wang, Lai-Guo; Cao, Zheng-Yi; Qian, Xu; Zhu, Lin; Cui, Da-Peng; Li, Ai-Dong; Wu, Di
2017-02-22
Al 2 O 3 - or HfO 2 -based nanocomposite structures with embedded CoPt x nanocrystals (NCs) on TiN-coated Si substrates have been prepared by combination of thermal atomic layer deposition (ALD) and plasma-enhanced ALD for resistive random access memory (RRAM) applications. The impact of CoPt x NCs and their average size/density on the resistive switching properties has been explored. Compared to the control sample without CoPt x NCs, ALD-derived Pt/oxide/100 cycle-CoPt x NCs/TiN/SiO 2 /Si exhibits a typical bipolar, reliable, and reproducible resistive switching behavior, such as sharp distribution of RRAM parameters, smaller set/reset voltages, stable resistance ratio (≥10 2 ) of OFF/ON states, better switching endurance up to 10 4 cycles, and longer data retention over 10 5 s. The possible resistive switching mechanism based on nanocomposite structures of oxide/CoPt x NCs has been proposed. The dominant conduction mechanisms in low- and high-resistance states of oxide-based device units with embedded CoPt x NCs are Ohmic behavior and space-charge-limited current, respectively. The insertion of CoPt x NCs can effectively improve the formation of conducting filaments due to the CoPt x NC-enhanced electric field intensity. Besides excellent resistive switching performances, the nanocomposite structures also simultaneously present ferromagnetic property. This work provides a flexible pathway by combining PEALD and TALD compatible with state-of-the-art Si-based technology for multifunctional electronic devices applications containing RRAM.
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…
Switching LPV Control with Double-Layer LPV Model for Aero-Engines
NASA Astrophysics Data System (ADS)
Tang, Lili; Huang, Jinquan; Pan, Muxuan
2017-11-01
To cover the whole range of operating conditions of aero-engine, a double-layer LPV model is built so as to take into account of the variability due to the flight altitude, Mach number and the rotational speed. With this framework, the problem of designing LPV state-feedback robust controller that guarantees desired bounds on both H_∞ and H_2 performances is considered. Besides this, to reduce the conservativeness caused by a single LPV controller of the whole flight envelope and the common Lyapunov function method, a new method is proposed to design a family of LPV switching controllers. The switching LPV controllers can ensure that the closed-loop system remains stable in the sense of Lyapunov under arbitrary switching logic. Meanwhile, the switching LPV controllers can ensure the parameters change smoothly. The validity and performance of the theoretical results are demonstrated through a numerical example.
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…
Cross-layer model design in wireless ad hoc networks for the Internet of Things.
Yang, Xin; Wang, Ling; Xie, Jian; Zhang, Zhaolin
2018-01-01
Wireless ad hoc networks can experience extreme fluctuations in transmission traffic in the Internet of Things, which is widely used today. Currently, the most crucial issues requiring attention for wireless ad hoc networks are making the best use of low traffic periods, reducing congestion during high traffic periods, and improving transmission performance. To solve these problems, the present paper proposes a novel cross-layer transmission model based on decentralized coded caching in the physical layer and a content division multiplexing scheme in the media access control layer. Simulation results demonstrate that the proposed model effectively addresses these issues by substantially increasing the throughput and successful transmission rate compared to existing protocols without a negative influence on delay, particularly for large scale networks under conditions of highly contrasting high and low traffic periods.
Cross-layer model design in wireless ad hoc networks for the Internet of Things
Wang, Ling; Xie, Jian; Zhang, Zhaolin
2018-01-01
Wireless ad hoc networks can experience extreme fluctuations in transmission traffic in the Internet of Things, which is widely used today. Currently, the most crucial issues requiring attention for wireless ad hoc networks are making the best use of low traffic periods, reducing congestion during high traffic periods, and improving transmission performance. To solve these problems, the present paper proposes a novel cross-layer transmission model based on decentralized coded caching in the physical layer and a content division multiplexing scheme in the media access control layer. Simulation results demonstrate that the proposed model effectively addresses these issues by substantially increasing the throughput and successful transmission rate compared to existing protocols without a negative influence on delay, particularly for large scale networks under conditions of highly contrasting high and low traffic periods. PMID:29734355
DOE Office of Scientific and Technical Information (OSTI.GOV)
Vishwanath, Suresh; Liu, Xinyu; Rouvimov, Sergei
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 MoTe 2 by MBE, MoSe 2 on Bi 2Se 3 SLs, transition metal dichalcogenide (TMD) SLs, and lateral junction between a quintuple atomic layer of Bi 2Te 3 andmore » a triple atomic layer of MoTe 2. 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
NASA Astrophysics Data System (ADS)
Go, Gyungchoon; Lee, Kyung-Jin; Kim, Young Keun
2017-04-01
Recently, the switching of a perpendicularly magnetized ferromagnet (FM) by injecting an in-plane current into an attached non-magnet (NM) has become of emerging technological interest. This magnetization switching is attributed to the spin-orbit torque (SOT) originating from the strong spin-orbit coupling of the NM layer. However, the switching efficiency of the NM/FM structure itself may be insufficient for practical use, as for example, in spin transfer torque (STT)-based magnetic random access memory (MRAM) devices. Here we investigate spin torque in an NM/FM structure with an additional spin polarizer (SP) layer abutted to the NM layer. In addition to the SOT contribution, a spin-polarized current from the SP layer creates an extra spin chemical potential difference at the NM/FM interface and gives rise to a STT on the FM layer. We show that, using typical parameters including device width, thickness, spin diffusion length, and the spin Hall angle, the spin torque from the SP layer can be much larger than that from the spin Hall effect (SHE) of the NM.
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.
Qiao, Mu; Liu, Honglin; Pang, Guanghui; Han, Shensheng
2017-08-29
Manipulating light non-invasively through inhomogeneous media is an attractive goal in many disciplines. Wavefront shaping and optical phase conjugation can focus light to a point. Transmission matrix method can control light on multiple output modes simultaneously. Here we report a non-invasive approach which enables three-dimension (3D) light control between two turbid layers. A digital optical phase conjugation mirror measured and conjugated the diffused wavefront, which originated from a quasi-point source on the front turbid layer and passed through the back turbid layer. And then, because of memory effect, the phase-conjugated wavefront could be used as a carrier wave to transport a pre-calculated wavefront through the back turbid layer. The pre-calculated wavefront could project a desired 3D light field inside the sample, which, in our experiments, consisted of two 220-grid ground glass plates spaced by a 20 mm distance. The controllable range of light, according to the memory effect, was calculated to be 80 mrad in solid angle and 16 mm on z-axis. Due to the 3D light control ability, our approach may find applications in photodynamic therapy and optogenetics. Besides, our approach can also be combined with ghost imaging or compressed sensing to achieve 3D imaging between turbid layers.
Active flow control insight gained from a modified integral boundary layer equation
NASA Astrophysics Data System (ADS)
Seifert, Avraham
2016-11-01
Active Flow Control (AFC) can alter the development of boundary layers with applications (e.g., reducing drag by separation delay or separating the boundary layers and enhancing vortex shedding to increase drag). Historically, significant effects of steady AFC methods were observed. Unsteady actuation is significantly more efficient than steady. Full-scale AFC tests were conducted with varying levels of success. While clearly relevant to industry, AFC implementation relies on expert knowledge with proven intuition and or costly and lengthy computational efforts. This situation hinders the use of AFC while simple, quick and reliable design method is absent. An updated form of the unsteady integral boundary layer (UIBL) equations, that include AFC terms (unsteady wall transpiration and body forces) can be used to assist in AFC analysis and design. With these equations and given a family of suitable velocity profiles, the momentum thickness can be calculated and matched with an outer, potential flow solution in 2D and 3D manner to create an AFC design tool, parallel to proven tools for airfoil design. Limiting cases of the UIBL equation can be used to analyze candidate AFC concepts in terms of their capability to modify the boundary layers development and system performance.
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.
NASA Astrophysics Data System (ADS)
Parikh, Hirak; Marzullo, Timothy C.; Kipke, Daryl R.
2009-04-01
Improving cortical prostheses requires the development of recording neural interfaces that are efficient in terms of providing maximal control information with minimal interface complexity. While the typical approaches have targeted neurons in the motor cortex with multiple penetrating shanks, an alternative approach is to determine an efficient distribution of electrode sites within the layers of the cortex with fewer penetrating shanks. The objective of this study was to compare unit activity in the upper and lower layers of the cortex with respect to movement and direction in order to inform the design of penetrating microelectrodes. Four rats were implanted bilaterally with multi-site single-shank silicon microelectrode arrays in the neck/shoulder region of the motor cortex. We simultaneously recorded unit activity across all layers of the motor cortex while the animal was engaged in a movement direction task. Localization of the electrode array within the different layers of the cortex was determined by histology. We denoted units from layers 2 and 3 and units as upper layer units, and units from layers 5 and 6 as lower layer units. Analysis of unit spiking activity demonstrated that both the upper and lower layers encode movement and direction information. Unit responses in either cortical layer of the cortex were not preferentially associated with contralateral or ipsilateral movement. Aggregate analysis (633 neurons) and best session analysis (75 neurons) indicated that units in the lower layers (layers 5, 6) are more likely to encode direction information when compared to units in the upper layers (layers 2, 3) (p< 0.05). These results suggest that electrode sites clustered in the lower layers provide access to more salient control information for cortical neuroprostheses.
Modification of WS2 nanosheets with controllable layers via oxygen ion irradiation
NASA Astrophysics Data System (ADS)
Song, Honglian; Yu, Xiaofei; Chen, Ming; Qiao, Mei; Wang, Tiejun; Zhang, Jing; Liu, Yong; Liu, Peng; Wang, Xuelin
2018-05-01
As one kind of two-dimensional materials, WS2 nanosheets have drawn much attention with different kinds of research methods. Yet ion irradiation method was barely used for WS2 nanosheets. In this paper, the structure, composition and optical band gap (Eg) of the multilayer WS2 films deposited by chemical vapor deposition (CVD) method on sapphire substrates before and after oxygen ion irradiation with different energy and fluences were studied. Precise tailored layer-structures and a controllable optical band gap of WS2 nanosheets were achieved after oxygen ion irradiation. The results shows higher energy oxygen irradiation changed the shape from triangular shaped grains to irregular rectangle shape but did not change 2H-WS2 phase structure. The intensity of E2g1 (Г) and A1g (Г) modes decreased and have small shifts after oxygen ion irradiation. The peak frequency difference between the E2g1 (Г) and A1g (Г) modes (Δω) decreased after oxygen ion irradiation, and this result indicates the number of layers decreased after oxygen ion irradiation. The Eg decreased with the increase of the energy and the fluence of oxygen ions. The number of layers, thickness and optical band gap changed after ion irradiation with different ion fluences and energies. The results proposed a new strategy for precise control of multilayer nanosheets and demonstrated the high applicability of ion irradiation in super-capacitors, field effect transistors and other applications.
Review of Research on Low-Profile Vortex Generators to Control Boundary-Layer Separation
NASA Technical Reports Server (NTRS)
Lin, John C.
2002-01-01
An in-depth review of boundary-layer flow-separation control by a passive method using low-profile vortex generators is presented. The generators are defined as those with a device height between 10% and 50% of the boundary layer thickness. Key results are presented for several research efforts, all of which were performed within the past decade and a half where the majority of these works emphasize experimentation with some recent efforts on numerical simulations. Topics of discussion consist of both basic fluid dynamics and applied aerodynamics research. The fluid dynamics research includes comparative studies on separation control effectiveness as well as device-induced vortex characterization and correlation. The comparative studies cover the controlling of low-speed separated flows in adverse pressure gradient and supersonic shock-induced separation. The aerodynamics research includes several applications for aircraft performance enhancement and covers a wide range of speeds. Significant performance improvements are achieved through increased lift and/or reduced drag for various airfoils-low-Reynolds number, high-lift, and transonic-as well as highly swept wings. Performance enhancements for non-airfoil applications include aircraft interior noise reduction, inlet flow distortion alleviation inside compact ducts, and a more efficient overwing fairing. The low-profile vortex generators are best for being applied to applications where flow-separation locations are relatively fixed and the generators can be placed reasonably close upstream of the separation. Using the approach of minimal near-wall proturbances through substantially reduced device height, these devices can produce streamwise vortices just strong enough to overcome the separation without unnecessarily persisting within the boundary layer once the flow-control objective is achieved. Practical advantages of low-profile vortex generators, such as their inherent simplicity and low device drag, are
Compositional control of continuously graded anode functional layer
NASA Astrophysics Data System (ADS)
McCoppin, J.; Barney, I.; Mukhopadhyay, S.; Miller, R.; Reitz, T.; Young, D.
2012-10-01
In this work, solid oxide fuel cells (SOFC's) are fabricated with linear-compositionally graded anode functional layers (CGAFL) using a computer-controlled compound aerosol deposition (CCAD) system. Cells with different CGAFL thicknesses (30 um and 50 um) are prepared with a continuous compositionally graded interface deposited between the electrolyte and anode support current collecting regions. The compositional profile was characterized using energy dispersive X-ray spectroscopic mapping. An analytical model of the compound aerosol deposition was developed. The model predicted compositional profiles for both samples that closely matched the measured profiles, suggesting that aerosol-based deposition methods are capable of creating functional gradation on length scales suitable for solid oxide fuel cell structures. The electrochemical performances of the two cells are analyzed using electrochemical impedance spectroscopy (EIS).
Controlling the Mechanical Properties of Bulk Metallic Glasses by Superficial Dealloyed Layer
Wang, Chaoyang; Li, Man; Zhu, Mo; Wang, Han; Qin, Chunling; Zhao, Weimin
2017-01-01
Cu50Zr45Al5 bulk metallic glass (BMG) presents high fracture strength. For improving its plasticity and controlling its mechanical properties, superficial dealloying of the BMG was performed. A composite structure containing an inner rod-shaped Cu-Zr-Al amorphous core with high strength and an outer dealloyed nanoporous layer with high energy absorption capacity was obtained. The microstructures and mechanical properties of the composites were studied in detail. It was found, for the first time, that the mechanical properties of Cu50Zr45Al5 BMG can be controlled by adjusting the width of the buffer deformation zone in the dealloyed layer, which can be easily manipulated with different dealloying times. As a result, the compressive strength, compressive strain, and energy absorption capacity of the BMGs can be effectively modulated from 0.9 to 1.5 GPa, from 2.9% to 4.7%, and from 29.1 to 40.2 MJ/m3, respectively. The paper may open a door for developing important engineering materials with regulable and comprehensive performances. PMID:29077072
In Situ Probing and Synthetic Control of Cationic Ordering in Ni-Rich Layered Oxide Cathodes
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhao, Jianqing; Zhang, Wei; Huq, Ashfia
Ni-rich layered oxides (LiNi1-xMxO2; M = Co, Mn, ...) are appealing alternatives to conventional LiCoO2 as cathodes in Li-ion batteries for automobile and other large-scale applications due to their high theoretical capacity and low cost. However, preparing stoichiometric LiNi1-xMxO2 with ordered layer structure and high reversible capacity, has proven difficult due to cation mixing in octahedral sites. Herein, in situ studies of synthesis reactions and the associated structural ordering in preparing LiNiO2 and the Co-substituted variant, LiNi0.8Co0.2O2, are made, to gain insights into synthetic control of the structure and electrochemical properties of Ni-rich layered oxides. Results from this study indicatemore » a direct transformation of the intermediate from the rock salt structure into hexagonal phase, and during the process, Co substitution facilities the nucleation of a Co-rich layered phase at low temperatures and subsequent growth and stabilization of solid solution Li(Ni, Co)O-2 upon further heat treatment. Optimal conditions are identified from the in situ studies and utilized to obtain stoichiometric LiNi0.8Co0.2O2 that exhibits high capacity (up to 200 mA h g(-1) ) with excellent retention. The findings shed light on designing high performance Ni-rich layered oxide cathodes through synthetic control of the structural ordering in the materials.« less
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.
Thomas, S; Kuiper, B; Hu, J; Smit, J; Liao, Z; Zhong, Z; Rijnders, G; Vailionis, A; Wu, R; Koster, G; Xia, J
2017-10-27
With reduced dimensionality, it is often easier to modify the properties of ultrathin films than their bulk counterparts. Strain engineering, usually achieved by choosing appropriate substrates, has been proven effective in controlling the properties of perovskite oxide films. An emerging alternative route for developing new multifunctional perovskite is by modification of the oxygen octahedral structure. Here we report the control of structural oxygen octahedral rotation in ultrathin perovskite SrRuO_{3} films by the deposition of a SrTiO_{3} capping layer, which can be lithographically patterned to achieve local control. Using a scanning Sagnac magnetic microscope, we show an increase in the Curie temperature of SrRuO_{3} due to the suppression octahedral rotations revealed by the synchrotron x-ray diffraction. This capping-layer-based technique may open new possibilities for developing functional oxide materials.
A Novel Reference Security Model with the Situation Based Access Policy for Accessing EPHR Data.
Gope, Prosanta; Amin, Ruhul
2016-11-01
Electronic Patient Health Record (EPHR) systems may facilitate a patient not only to share his/her health records securely with healthcare professional but also to control his/her health privacy, in a convenient and easy way even in case of emergency. In order to fulfill these requirements, it is greatly desirable to have the access control mechanism which can efficiently handle every circumstance without negotiating security. However, the existing access control mechanisms used in healthcare to regulate and restrict the disclosure of patient data are often bypassed in case of emergencies. In this article, we propose a way to securely share EPHR data under any situation including break-the-glass (BtG) without compromising its security. In this regard, we design a reference security model, which consists of a multi-level data flow hierarchy, and an efficient access control framework based on the conventional Role-Based Access Control (RBAC) and Mandatory Access Control (MAC) policies.
Access Scheme for Controlling Mobile Agents and its Application to Share Medical Information.
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.
Wang, Dawei; Kou, Ronghui; Ren, Yang; Sun, Cheng-Jun; Zhao, Hu; Zhang, Ming-Jian; Li, Yan; Huq, Ashifia; Ko, J Y Peter; Pan, Feng; Sun, Yang-Kook; Yang, Yong; Amine, Khalil; Bai, Jianming; Chen, Zonghai; Wang, Feng
2017-10-01
Nickel-rich layered transition metal oxides, LiNi 1- x (MnCo) x O 2 (1-x ≥ 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi 0.7 Mn 0.15 Co 0.15 O 2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strong temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Dawei; Kou, Ronghui; Ren, Yang
Nickel-rich layered transition metal oxides, LiNi1-x(MnCo)(x)O-2 (1-x >= 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi0.7Mn0.15Co0.15O2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strong temperature dependence of the kinetics of cationicmore » ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Dawei; Kou, Ronghui; Ren, Yang
Nickel-rich layered transition metal oxides, LiNi 1-x(MnCo) xO 2 (1-x ≥ 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi 0.7Mn 0.15Co 0.15O 2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strongmore » temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs« less
Wang, Dawei; Kou, Ronghui; Ren, Yang; ...
2017-08-25
Nickel-rich layered transition metal oxides, LiNi 1-x(MnCo) xO 2 (1-x ≥ 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi 0.7Mn 0.15Co 0.15O 2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strongmore » temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs« less
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
Ozone Layer Research and Technical Resources
Access information on research and technical resources related to ozone layer science. This page provides links to research efforts led by organizations such as the National Oceanic and Atmospheric Administration, the United Nations Environment Program, an
NASA Technical Reports Server (NTRS)
Goodrich, John W.
2017-01-01
This paper presents results from numerical experiments for controlling the error caused by a damping layer boundary treatment when simulating the propagation of an acoustic signal from a continuous pressure source. The computations are with the 2D Linearized Euler Equations (LEE) for both a uniform mean flow and a steady parallel jet. The numerical experiments are with algorithms that are third, fifth, seventh and ninth order accurate in space and time. The numerical domain is enclosed in a damping layer boundary treatment. The damping is implemented in a time accurate manner, with simple polynomial damping profiles of second, fourth, sixth and eighth power. At the outer boundaries of the damping layer the propagating solution is uniformly set to zero. The complete boundary treatment is remarkably simple and intrinsically independant from the dimension of the spatial domain. The reported results show the relative effect on the error from the boundary treatment by varying the damping layer width, damping profile power, damping amplitude, propagtion time, grid resolution and algorithm order. The issue that is being addressed is not the accuracy of the numerical solution when compared to a mathematical solution, but the effect of the complete boundary treatment on the numerical solution, and to what degree the error in the numerical solution from the complete boundary treatment can be controlled. We report maximum relative absolute errors from just the boundary treatment that range from O[10-2] to O[10-7].
Tandem Solar Cells from Accessible Low Band-Gap Polymers Using an Efficient Interconnecting Layer.
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.
An effective and secure key-management scheme for hierarchical access control in E-medicine system.
Odelu, Vanga; Das, Ashok Kumar; Goswami, Adrijit
2013-04-01
Recently several hierarchical access control schemes are proposed in the literature to provide security of e-medicine systems. However, most of them are either insecure against 'man-in-the-middle attack' or they require high storage and computational overheads. Wu and Chen proposed a key management method to solve dynamic access control problems in a user hierarchy based on hybrid cryptosystem. Though their scheme improves computational efficiency over Nikooghadam et al.'s approach, it suffers from large storage space for public parameters in public domain and computational inefficiency due to costly elliptic curve point multiplication. Recently, Nikooghadam and Zakerolhosseini showed that Wu-Chen's scheme is vulnerable to man-in-the-middle attack. In order to remedy this security weakness in Wu-Chen's scheme, they proposed a secure scheme which is again based on ECC (elliptic curve cryptography) and efficient one-way hash function. However, their scheme incurs huge computational cost for providing verification of public information in the public domain as their scheme uses ECC digital signature which is costly when compared to symmetric-key cryptosystem. In this paper, we propose an effective access control scheme in user hierarchy which is only based on symmetric-key cryptosystem and efficient one-way hash function. We show that our scheme reduces significantly the storage space for both public and private domains, and computational complexity when compared to Wu-Chen's scheme, Nikooghadam-Zakerolhosseini's scheme, and other related schemes. Through the informal and formal security analysis, we further show that our scheme is secure against different attacks and also man-in-the-middle attack. Moreover, dynamic access control problems in our scheme are also solved efficiently compared to other related schemes, making our scheme is much suitable for practical applications of e-medicine systems.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lentz, Levi C.; Kolb, Brian; Kolpak, Alexie M.
Layered transition metal phosphates and phosphites (TMPs) are a class of 2D materials bound togetherviavan der Waals interactions. Through simple functionalization, band energies can be systematically controlled.
Li, Xiang Yuan; Shao, Xing Long; Wang, Yi Chuan; Jiang, Hao; Hwang, Cheol Seong; Zhao, Jin Shi
2017-02-09
Ta 2 O 5 has been an appealing contender for the resistance switching random access memory (ReRAM). The resistance switching (RS) in this material is induced by the repeated formation and rupture of the conducting filaments (CFs) in the oxide layer, which are accompanied by the almost inevitable randomness of the switching parameters. In this work, a 1 to 2 nm-thick Ti layer was deposited on the 10 nm-thick Ta 2 O 5 RS layer, which greatly improved the RS performances, including the much-improved switching uniformity. The Ti metal layer was naturally oxidized to TiO x (x < 2) and played the role of a series resistor, whose resistance value was comparable to the on-state resistance of the Ta 2 O 5 RS layer. The series resistor TiO x efficiently suppressed the adverse effects of the voltage (or current) overshooting at the moment of switching by the appropriate voltage partake effect, which increased the controllability of the CF formation and rupture. The switching cycle endurance was increased by two orders of magnitude even during the severe current-voltage sweep tests compared with the samples without the thin TiO x layer. The Ti deposition did not induce any significant overhead to the fabrication process, making the process highly promising for the mass production of a reliable ReRAM.
Simulation of thermal environment in a three-layer vinyl greenhouse by natural ventilation control
NASA Astrophysics Data System (ADS)
Jin, Tea-Hwan; Shin, Ki-Yeol; Yoon, Si-Won; Im, Yong-Hoon; Chang, Ki-Chang
2017-11-01
A high energy, efficient, harmonious, ecological greenhouse has been highlighted by advanced future agricultural technology recently. This greenhouse is essential for expanding the production cycle toward growth conditions through combined thermal environmental control. However, it has a negative effect on farming income via huge energy supply expenses. Because not only production income, but operating costs related to thermal load for thermal environment control is important in farming income, it needs studies such as a harmonious ecological greenhouse using natural ventilation control. This study is simulated for energy consumption and thermal environmental conditions in a three-layered greenhouse by natural ventilation using window opening. A virtual 3D model of a three-layered greenhouse was designed based on the real one in the Gangneung area. This 3D model was used to calculate a thermal environment state such as indoor temperature, relative humidity, and thermal load in the case of a window opening rate from 0 to 100%. There was also a heat exchange operated for heating or cooling controlled by various setting temperatures. The results show that the cooling load can be reduced by natural ventilation control in the summer season, and the heat exchange capacity for heating can also be simulated for growth conditions in the winter season.
Control of flow separation in a turbulent boundary layer
NASA Astrophysics Data System (ADS)
Cho, Minjeong; Choi, Sangho; Choi, Haecheon
2015-11-01
Towards the development of successful control methods for separation delay in a turbulent boundary layer, we adopt a model flow field, in which a turbulent separation occurs above a flat plate (Na and Moin 1998 JFM), and apply controls to this flow for reducing the size of the separation bubble and investigating the interaction between the forcing and flow near the separation bubble. We provide a single-frequency forcing with zero net mass flow rate at the upstream of the separation bubble. At low forcing frequencies, spanwise vortices are generated and travel downstream, bringing high momentum toward the wall and reducing the size of the separation bubble. Also, these vortices cause the separation and reattachment points to travel downstream. On the other hand, at high forcing frequencies, the size of the separation bubble becomes smaller and larger in time, respectively, due to the pressure gradient alternating favorably and adversely in time. Supported by NRF-2011-0028032 and 2014048162.
Medium Access Control Protocols for Cognitive Radio Ad Hoc Networks: A Survey
Islam, A. K. M. Muzahidul; Baharun, Sabariah; Mansoor, Nafees
2017-01-01
New wireless network paradigms will demand higher spectrum use and availability to cope with emerging data-hungry devices. Traditional static spectrum allocation policies cause spectrum scarcity, and new paradigms such as Cognitive Radio (CR) and new protocols and techniques need to be developed in order to have efficient spectrum usage. Medium Access Control (MAC) protocols are accountable for recognizing free spectrum, scheduling available resources and coordinating the coexistence of heterogeneous systems and users. This paper provides an ample review of the state-of-the-art MAC protocols, which mainly focuses on Cognitive Radio Ad Hoc Networks (CRAHN). First, a description of the cognitive radio fundamental functions is presented. Next, MAC protocols are divided into three groups, which are based on their channel access mechanism, namely time-slotted protocol, random access protocol and hybrid protocol. In each group, a detailed and comprehensive explanation of the latest MAC protocols is presented, as well as the pros and cons of each protocol. A discussion on future challenges for CRAHN MAC protocols is included with a comparison of the protocols from a functional perspective. PMID:28926952
Thomas, S.; Kuiper, B.; Hu, J.; ...
2017-10-27
With reduced dimensionality, it is often easier to modify the properties of ultrathin films than their bulk counterparts. Strain engineering, usually achieved by choosing appropriate substrates, has been proven effective in controlling the properties of perovskite oxide films. An emerging alternative route for developing new multifunctional perovskite is by modification of the oxygen octahedral structure. Here we report the control of structural oxygen octahedral rotation in ultrathin perovskite SrRuO 3 films by the deposition of a SrTiO 3 capping layer, which can be lithographically patterned to achieve local control. Here, using a scanning Sagnac magnetic microscope, we show an increasemore » in the Curie temperature of SrRuO 3 due to the suppression octahedral rotations revealed by the synchrotron x-ray diffraction. Lastly, this capping-layer-based technique may open new possibilities for developing functional oxide materials.« less
In Situ Probing and Synthetic Control of Cationic Ordering in Ni-Rich Layered Oxide Cathodes
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhao, Jianqing; Zhang, Wei; Huq, Ashfia
Ni-rich layered oxides (LiNi 1-xM xO 2; M=Co, Mn, …) are appealing alternatives to conventional LiCoO 2 as cathodes in Li-ion batteries for automobile and other large-scale applications due to their high theoretical capacity and low cost. However, preparing stoichiometric LiNi 1-xM xO 2 with ordered layer structure and high reversible capacity, has proven difficult due to Ni 2+/Li + cation mixing in octahedral sites. Herein, we report on in-situ studies of synthesis reactions and the associated structural ordering in preparing LiNiO 2 and the Co-substituted variant, LiNi 0.8Co 0.2O 2, thereby gaining insights into synthetic control of the structuremore » and electrochemical properties of Ni-rich layered oxides. Results from this study indicate a direct transformation of the intermediate from the rock salt structure into hexagonal phase, and during the process, Co substitution facilities the nucleation of a Co-rich layered phase at low temperatures and subsequent growth and stabilization of solid solution Li(Ni, Co)O 2 upon heat treatment in a highly oxidation environment. Optimal conditions were identified from the in-situ studies and utilized in obtaining stoichiometric LiNi 0.8Co 0.2O 2 that exhibits high capacity of about 200 mAh/g with excellent retention. The findings shed light on designing Ni-rich layered oxide cathodes with enhanced electrochemical properties through synthetic control of the structural ordering in the materials.« less
In Situ Probing and Synthetic Control of Cationic Ordering in Ni-Rich Layered Oxide Cathodes
Zhao, Jianqing; Zhang, Wei; Huq, Ashfia; ...
2016-10-17
Ni-rich layered oxides (LiNi 1-xM xO 2; M=Co, Mn, …) are appealing alternatives to conventional LiCoO 2 as cathodes in Li-ion batteries for automobile and other large-scale applications due to their high theoretical capacity and low cost. However, preparing stoichiometric LiNi 1-xM xO 2 with ordered layer structure and high reversible capacity, has proven difficult due to Ni 2+/Li + cation mixing in octahedral sites. Herein, we report on in-situ studies of synthesis reactions and the associated structural ordering in preparing LiNiO 2 and the Co-substituted variant, LiNi 0.8Co 0.2O 2, thereby gaining insights into synthetic control of the structuremore » and electrochemical properties of Ni-rich layered oxides. Results from this study indicate a direct transformation of the intermediate from the rock salt structure into hexagonal phase, and during the process, Co substitution facilities the nucleation of a Co-rich layered phase at low temperatures and subsequent growth and stabilization of solid solution Li(Ni, Co)O 2 upon heat treatment in a highly oxidation environment. Optimal conditions were identified from the in-situ studies and utilized in obtaining stoichiometric LiNi 0.8Co 0.2O 2 that exhibits high capacity of about 200 mAh/g with excellent retention. The findings shed light on designing Ni-rich layered oxide cathodes with enhanced electrochemical properties through synthetic control of the structural ordering in the materials.« less
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…
Non-volatile magnetic random access memory
NASA Technical Reports Server (NTRS)
Katti, Romney R. (Inventor); Stadler, Henry L. (Inventor); Wu, Jiin-Chuan (Inventor)
1994-01-01
Improvements are made in a non-volatile magnetic random access memory. Such a memory is comprised of an array of unit cells, each having a Hall-effect sensor and a thin-film magnetic element made of material having an in-plane, uniaxial anisotropy and in-plane, bipolar remanent magnetization states. The Hall-effect sensor is made more sensitive by using a 1 m thick molecular beam epitaxy grown InAs layer on a silicon substrate by employing a GaAs/AlGaAs/InAlAs superlattice buffering layer. One improvement avoids current shunting problems of matrix architecture. Another improvement reduces the required magnetizing current for the micromagnets. Another improvement relates to the use of GaAs technology wherein high electron-mobility GaAs MESFETs provide faster switching times. Still another improvement relates to a method for configuring the invention as a three-dimensional random access memory.
30 CFR 817.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 817.11. The operator shall...
30 CFR 817.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 817.11. The operator shall...
30 CFR 817.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 817.11. The operator shall...
30 CFR 817.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 817.11. The operator shall...
30 CFR 817.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 817.11. The operator shall...
Assessing Layered Materials in Gale Crater
NASA Technical Reports Server (NTRS)
Bridges, N. T.
2001-01-01
The recent analysis of high resolution Mars Orbiter Camera (MOC) images of layered outcrops in equatorial regions reinforces two important ideas, which will probably eventually become paradigms, about Mars: 1) It has had a long, complex geologic history marked by change, as manifested in the different layers observed, and 2) Standing bodies of water existed for substantial lengths of time, indicating clement conditions possibly conducive to life. Although observations of layering and evidence for lakes and oceans has been reported for years based on Mariner 9 and Viking data, the MOC data show that this layering is much more pervasive and complex than previously thought. These layered sites are ideal for studying the geologic, and possibly biologic, history of Mars. Here, a layered site within Gale Crater is advocated as a Mars Exploration Rover (MER) target. This is one of the few layered areas within closed depressions (e.g., other craters and Vallis Marineris) that meets the landing site constraints and is accessible to both MER A and B.
Pathways of soil moisture controls on boundary layer dynamics
NASA Astrophysics Data System (ADS)
Siqueira, M.; Katul, G.; Porporato, A.
2007-12-01
Soil moisture controls on precipitation are now receiving significant attention in climate systems because the memory of their variability is much slower than the memory of the fast atmospheric processes. We propose a new model that integrates soil water dynamics, plant hydraulics and stomatal responses to water availability to estimate root water uptake and available energy partitioning, as well as feedbacks to boundary layer dynamics (in terms of water vapor and heat input to the atmospheric system). Using a simplified homogenization technique, the model solves the intrinsically 3-D soil water movement equations by two 1-D coupled Richards' equations. The first resolves the radial water flow from bulk soil to soil-root interface to estimate root uptake (assuming the vertical gradients in moisture persist during the rapid lateral flow), and then it solves vertical water movement through the soil following the radial moisture adjustments. The coupling between these two equations is obtained by area averaging the soil moisture in the radial domain (i.e. homogenization) to calculate the vertical fluxes. For each vertical layer, the domain is discretized in axi-symmetrical grid with constant soil properties. This is deemed to be appropriate given the fact that the root uptake occurs on much shorter time scales closely following diurnal cycles, while the vertical water movement is more relevant to the inter-storm time scale. We show that this approach was able to explicitly simulate known features of root uptake such as diurnal hysteresis of canopy conductance, water redistribution by roots (hydraulic lift) and downward shift of root uptake during drying cycles. The model is then coupled with an atmospheric boundary layer (ABL) growth model thereby permitting us to explore low-dimensional elements of the interaction between soil moisture and ABL states commensurate with the lifting condensation level.
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.
Improved CLARAty Functional-Layer/Decision-Layer Interface
NASA Technical Reports Server (NTRS)
Estlin, Tara; Rabideau, Gregg; Gaines, Daniel; Johnston, Mark; Chouinard, Caroline; Nessnas, Issa; Shu, I-Hsiang
2008-01-01
Improved interface software for communication between the CLARAty Decision and Functional layers has been developed. [The Coupled Layer Architecture for Robotics Autonomy (CLARAty) was described in Coupled-Layer Robotics Architecture for Autonomy (NPO-21218), NASA Tech Briefs, Vol. 26, No. 12 (December 2002), page 48. To recapitulate: the CLARAty architecture was developed to improve the modularity of robotic software while tightening coupling between planning/execution and basic control subsystems. Whereas prior robotic software architectures typically contained three layers, the CLARAty contains two layers: a decision layer (DL) and a functional layer (FL).] Types of communication supported by the present software include sending commands from DL modules to FL modules and sending data updates from FL modules to DL modules. The present software supplants prior interface software that had little error-checking capability, supported data parameters in string form only, supported commanding at only one level of the FL, and supported only limited updates of the state of the robot. The present software offers strong error checking, and supports complex data structures and commanding at multiple levels of the FL, and relative to the prior software, offers a much wider spectrum of state-update capabilities.
Chromatic control in coextruded layered polymer microlenses
NASA Astrophysics Data System (ADS)
Crescimanno, Michael; Oder, Tom N.; Andrews, James H.; Zhou, Chuanhong; Petrus, Joshua B.; Merlo, Cory; Bagheri, Cameron; Hetzel, Connor; Tancabel, James; Singer, Kenneth D.; Baer, Eric
2014-12-01
We describe the formation, characterization and theoretical understanding of microlenses comprised of alternating polystyrene and polymethylmethacrylate layers produced by multilayer coextrusion. These lenses are fabricated by photolithography, using a grayscale mask followed by plasma etching, so that the refractive index alternation of the bilayer stack appears across the radius of the microlens. The alternating quarter-wave thick layers form a one-dimensional photonic crystal whose dispersion augments the material dispersion, allowing one to sculpt the chromatic dispersion of the lens by adjusting the layered structure. Using Huygen's principle, we model our experimental measurements of the focal length of these lenses across the reflection band of the multilayer polymer film from which the microlens is fashioned. For a 56 micron diameter multilayered lens of focal length 300 microns, we measured a nearly 25 percent variation in the focal length across a shallow, 50 nm-wide reflection band.
Control of Evaporation Behavior of an Inkjet-Printed Dielectric Layer Using a Mixed-Solvent System
NASA Astrophysics Data System (ADS)
Yang, Hak Soon; Kang, Byung Ju; Oh, Je Hoon
2016-01-01
In this study, the evaporation behavior and the resulting morphology of inkjet-printed dielectric layers were controlled using a mixed-solvent system to fabricate uniform poly-4-vinylphenol (PVP) dielectric layers without any pinholes. The mixed-solvent system consisted of two different organic solvents: 1-hexanol and ethanol. The effects of inkjet-printing variables such as overlap condition, substrate temperature, and different printing sequences (continuous and interlacing printing methods) on the inkjet-printed dielectric layer were also investigated. Increasing volume fraction of ethanol (VFE) is likely to reduce the evaporation rate gradient and the drying time of the inkjet-printed dielectric layer; this diminishes the coffee stain effect and thereby improves the uniformity of the inkjet-printed dielectric layer. However, the coffee stain effect becomes more severe with an increase in the substrate temperature due to the enhanced outward convective flow. The overlap condition has little effect on the evaporation behavior of the printed dielectric layer. In addition, the interlacing printing method results in either a stronger coffee stain effect or wavy structures of the dielectric layers depending on the VFE of the PVP solution. All-inkjet-printed capacitors without electrical short circuiting can be successfully fabricated using the optimized PVP solution (VFE = 0.6); this indicates that the mixed-solvent system is expected to play an important role in the fabrication of high-quality inkjet-printed dielectric layers in various printed electronics applications.
Spatial and layer-controlled variability in fracture networks
NASA Astrophysics Data System (ADS)
Procter, Andrew; Sanderson, David J.
2018-03-01
Topological sampling, based on 1) node counting and 2) circular sampling areas, is used to measure fracture intensity in surface exposures of a layered limestone/shale sequence in north Somerset, UK. This method provides similar levels of precision as more traditional line samples, but is about 10 times quicker and allows characterization of the network topology. Georeferencing of photographs of the sample sites allows later analysis of trace lengths and orientations, and identification of joint set development. ANOVA tests support a complex interaction of within-layer, between-layer and between-location variability in fracture intensity, with the different layers showing anomalous intensity at different locations. This variation is not simply due to bed thickness, nor can it be related to any obvious compositional or textural variation between the limestone beds. These results are used to assess approaches to the spatial mapping of fracture intensity.
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…
30 CFR 816.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-SURFACE MINING ACTIVITIES § 816.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 816.11. The operator shall— (1...
30 CFR 816.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-SURFACE MINING ACTIVITIES § 816.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 816.11. The operator shall— (1...
30 CFR 816.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-SURFACE MINING ACTIVITIES § 816.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 816.11. The operator shall— (1...
30 CFR 816.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-SURFACE MINING ACTIVITIES § 816.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 816.11. The operator shall— (1...
30 CFR 816.66 - Use of explosives: Blasting signs, warnings, and access control.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Use of explosives: Blasting signs, warnings... STANDARDS-SURFACE MINING ACTIVITIES § 816.66 Use of explosives: Blasting signs, warnings, and access control. (a) Blasting signs. Blasting signs shall meet the specifications of § 816.11. The operator shall— (1...
Tel-Vered, Ran; Kahn, Jason S; Willner, Itamar
2016-01-06
Layered metal nanoparticle (NP) assemblies provide highly porous and conductive composites of unique electrical and optical (plasmonic) properties. Two methods to construct layered metal NP matrices are described, and these include the layer-by-layer deposition of NPs, or the electropolymerization of monolayer-functionalized NPs, specifically thioaniline-modified metal NPs. The layered NP composites are used as sensing matrices through the use of electrochemistry or surface plasmon resonance (SPR) as transduction signals. The crosslinking of the metal NP composites with molecular receptors, or the imprinting of molecular recognition sites into the electropolymerized NP matrices lead to selective and chiroselective sensing interfaces. Furthermore, the electrosynthesis of redox-active, imprinted, bis-aniline bridged Au NP composites yields electrochemically triggered "sponges" for the switchable uptake and release of electron-acceptor substrates, and results in conductive surfaces of electrochemically controlled wettability. Also, photosensitizer-relay-crosslinked Au NP composites, or electrochemically polymerized layered semiconductor quantum dot/metal NP matrices on electrodes, are demonstrated as functional nanostructures for photoelectrochemical applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Towards precise defect control in layered oxide structures by using oxide molecular beam epitaxy
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
Code of Federal Regulations, 2010 CFR
2010-10-01
... Control Act Confidential Business Information (APR 1996). 1552.235-75 Section 1552.235-75 Federal... Confidential Business Information (APR 1996). As prescribed in 1535.007(b), insert the following provision: Access to Toxic Substances Control Act Confidential Business Information (APR 1996) In order to perform...
Characterization of triple layers
NASA Astrophysics Data System (ADS)
Otero, Toribio F.; Cortes, M. Teresa
2001-07-01
We reported the characterization of a macroscopic electrochemomechanical actuator like triple layer (3x1 cm) formed by polypyrrole)/double- sided, non-conducting and flexible tape/ polypyrrole that works in liquid electrolytes under electrochemical control. This triple layer has characteristics of artificial muscle. The influence of variables that control the volume change in the polymer as electrolyte concentration, or temperature has been studied. Variations of time, energy and charge under different conditions are described. We have found that the triple layer acts, at the same time, as sensor and actuator. Therefore, physical magnitudes like the electrolyte concentration or the temperature in the cell can be obtained from electrical energy consumed by a muscle. We have evaluated the influence of variables as area of the triple layer or the trailing weight, which don't participate in the electrochemical reaction. We propose an explication to the results, which show a correlation between the trailed mass and the consumed charge required to move a constant angle those masses by the triple layer. When different surface areas of the triple layer has been evaluated we found that the consumed electrical charge is proportional to area (the mass) of the triple layer. The triple layer can make macroscopical movements in short times, their position is absolutely controlled with the electrical charge, and it has capacity to lift masses. These characteristics allow their use in the design of tools. So, we present a macroscopic tool constituted by two triple layers, which allows catch and translate objects in liquid medium (nipper).
Controlled Gas Exfoliation of Boron Nitride into Few-Layered Nanosheets
Zhu, Wenshuai; Gao, Xiang; Li, Qian; ...
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 N 2 (L-N 2). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h-BN and the cryogenic L-N 2 gasification to exfoliate the h-BN. The produced BNNS after ten cycles (BNNS-10) consisted primarily of fewer than five atomic layersmore » with high a mass yield of 16~20%. N 2 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-N 2 penetrates into the interlayers of h-BN along the curling edge, followed by an immediate drastic gasification of L-N 2, 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
Circular Dichroism Control of Tungsten Diselenide (WSe2) Atomic Layers with Plasmonic Metamolecules.
Lin, Hsiang-Ting; Chang, Chiao-Yun; Cheng, Pi-Ju; Li, Ming-Yang; Cheng, Chia-Chin; Chang, Shu-Wei; Li, Lance L J; Chu, Chih-Wei; Wei, Pei-Kuen; Shih, Min-Hsiung
2018-05-09
Controlling circularly polarized (CP) states of light is critical to the development of functional devices for key and emerging applications such as display technology and quantum communication, and the compact circular polarization-tunable photon source is one critical element to realize the applications in the chip-scale integrated system. The atomic layers of transition metal dichalcogenides (TMDCs) exhibit intrinsic CP emissions and are potential chiroptical materials for ultrathin CP photon sources. In this work, we demonstrated CP photon sources of TMDCs with device thicknesses approximately 50 nm. CP photoluminescence from the atomic layers of tungsten diselenide (WSe 2 ) was precisely controlled with chiral metamolecules (MMs), and the optical chirality of WSe 2 was enhanced more than 4 times by integrating with the MMs. Both the enhanced and reversed circular dichroisms had been achieved. Through integrations of the novel gain material and plasmonic structure which are both low-dimensional, a compact device capable of efficiently manipulating emissions of CP photon was realized. These ultrathin devices are suitable for important applications such as the optical information technology and chip-scale biosensing.
An Ultra-low-power Medium Access Control Protocol for Body Sensor Network.
Li, Huaming; Tan, Jindong
2005-01-01
In this paper, a medium access control (MAC) protocol designed for Body Sensor Network (BSN-MAC) is proposed. BSN-MAC is an adaptive, feedback-based and IEEE 802.15.4-compatible MAC protocol. Due to the traffic coupling and sensor diversity characteristics of BSNs, common MAC protocols can not satisfy the unique requirements of the biomedical sensors in BSN. BSN-MAC exploits the feedback information from the deployed sensors to form a closed-loop control of the MAC parameters. A control algorithm is proposed to enable the BSN coordinator to adjust parameters of the IEEE 802.15.4 superframe to achieve both energy efficiency and low latency on energy critical nodes. We evaluate the performance of BSN-MAC using energy efficiency as the primary metric.
Evaluation of Standards for Access Control Enabling PHR-S Federation.
Mense, Alexander; Urbauer, Philipp; Sauermann, Stefan
2017-01-01
The adoption of the Internet of Things (IoT) and mobile applications in the healthcare may transform the healthcare industry by offering better disease tracking and management as well as patient empowerment. Unfortunately, almost all of these new systems set up their own ecosystem and to be really valuable for the care process they need to be integrated or federated with user managed access control services based on international standards and profiles to enable interoperability. Thus, this work presents the results of an evaluation of available specifications for federated authorization, based on a set of basic requirements.
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.
Distributed Fair Auto Rate Medium Access Control for IEEE 802.11 Based WLANs
NASA Astrophysics Data System (ADS)
Zhu, Yanfeng; Niu, Zhisheng
Much research has shown that a carefully designed auto rate medium access control can utilize the underlying physical multi-rate capability to exploit the time-variation of the channel. In this paper, we develop a simple analytical model to elucidate the rule that maximizes the throughput of RTS/CTS based multi-rate wireless local area networks. Based on the discovered rule, we propose two distributed fair auto rate medium access control schemes called FARM and FARM+ from the view-point of throughput fairness and time-share fairness, respectively. With the proposed schemes, after receiving a RTS frame, the receiver selectively returns the CTS frame to inform the transmitter the maximum feasible rate probed by the signal-to-noise ratio of the received RTS frame. The key feature of the proposed schemes is that they are capable of maintaining throughput/time-share fairness in asymmetric situation where the distribution of SNR varies with stations. Extensive simulation results show that the proposed schemes outperform the existing throughput/time-share fair auto rate schemes in time-varying channel conditions.
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
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
2011-12-01
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. 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. 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. 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 global NTD database is feasible and should be expanded
NASA Technical Reports Server (NTRS)
Asbury, Scott C.; Hunter, Craig A.
1999-01-01
An investigation was conducted in the model preparation area of the Langley 16-Foot Transonic Tunnel to determine the internal performance of a fixed-geometry exhaust nozzle incorporating porous cavities for shock-boundary layer interaction control. Testing was conducted at static conditions using a sub-scale nozzle model with one baseline and 27 porous configurations. For the porous configurations, the effects of percent open porosity, hole diameter, and cavity depth were determined. All tests were conducted with no external flow at nozzle pressure ratios from 1.25 to approximately 9.50. Results indicate that baseline nozzle performance was dominated by unstable, shock-induced, boundary-layer separation at over-expanded conditions. Porous configurations were capable of controlling off-design separation in the nozzle by either alleviating separation or encouraging stable separation of the exhaust flow. The ability of the porous nozzle concept to alternately alleviate separation or encourage stable separation of exhaust flow through shock-boundary layer interaction control offers tremendous off-design performance benefits for fixed-geometry nozzle installations. In addition, the ability to encourage separation on one divergent flap while alleviating it on the other makes it possible to generate thrust vectoring using a fixed-geometry nozzle.
NASA Astrophysics Data System (ADS)
Bendine, K.; Boukhoulda, F. B.; Nouari, M.; Satla, Z.
2016-12-01
This paper reports on a study of active vibration control of functionally graded beams with upper and lower surface-bonded piezoelectric layers. The model is based on higher-order shear deformation theory and implemented using the finite element method (FEM). The proprieties of the functionally graded beam (FGB) are graded along the thickness direction. The piezoelectric actuator provides a damping effect on the FGB by means of a velocity feedback control algorithm. A Matlab program has been developed for the FGB model and compared with ANSYS APDL. Using Newmark's method numerical solutions are obtained for the dynamic equations of FGB with piezoelectric layers. Numerical results show the effects of the constituent volume fraction and the influence the feedback control gain on the frequency and dynamic response of FGBs.
Nano suboxide layer generated in Ta{sub 2}O{sub 5} by Ar{sup +} ion irradiation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Song, W. D., E-mail: song-wendong@dsi.a-star.edu.sg, E-mail: ying-ji-feng@dsi.a-star.edu.sg; Ying, J. F., E-mail: song-wendong@dsi.a-star.edu.sg, E-mail: ying-ji-feng@dsi.a-star.edu.sg; He, W.
2015-01-19
Ta{sub 2}O{sub 5}/TaO{sub x} heterostructure has become a leading oxide layer in memory cells and/or a bidirectional selector for resistive random access memory (RRAM). Although atomic layer deposition (ALD) was found to be uniquely suitable for depositing uniform and conformal films on complex topographies, it is hard to use ALD to grow suboxide TaO{sub x} layer. In this study, tantalum oxide films with a composition of Ta{sub 2}O{sub 5} were grown by ALD. Using Ar{sup +} ion irradiation, the suboxide was formed in the top layer of Ta{sub 2}O{sub 5} films by observing the Ta core level shift toward lowermore » binding energy with angle-resolved X-ray photoelectron spectroscopy. By controlling the energy and irradiation time of an Ar{sup +} ion beam, Ta{sub 2}O{sub 5}/TaO{sub x} heterostructure can be reliably produced on ALD films, which provides a way to fabricate the critical switching layers of RRAM.« less
NASA Astrophysics Data System (ADS)
Huang, Liang; Ao, Lijiao; Xie, Xiaobin; Gao, Guanhui; Foda, Mohamed F.; Su, Wu
2014-12-01
Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m2 g-1). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi-functionality.Superparamagnetic iron oxide nanoparticle layers with high packing density and controlled thickness were in situ deposited on metal-affinity organic templates (polydopamine spheres), via one-pot thermal decomposition. The as synthesized hybrid structure served as a facile nano-scaffold toward hollow-mesoporous magnetic carriers, through surfactant-assisted silica encapsulation and its subsequent calcination. Confined but accessible gold nanoparticles were successfully incorporated into these carriers to form a recyclable catalyst, showing quick magnetic response and a large surface area (642.5 m2 g-1). Current nano-reactors exhibit excellent catalytic performance and high stability in reduction of 4-nitrophenol, together with convenient magnetic separability and good reusability. The integration of compact iron oxide nanoparticle layers with programmable polydopamine templates paves the way to fabricate magnetic-response hollow structures, with high permeability and multi
Access control design on highway interchanges.
DOT National Transportation Integrated Search
2008-01-01
The adequate spacing and design of access to crossroads in the vicinity of freeway ramps are critical to the safety and traffic operations of both the freeway and the crossroad. The research presented in this report develops a methodology to evaluate...
NASA Astrophysics Data System (ADS)
Liu, Xiaosong; Shan, Zebiao; Li, Yuanchun
2017-04-01
Pinpoint landing is a critical step in some asteroid exploring missions. This paper is concerned with the descent trajectory control for soft touching down on a small irregularly-shaped asteroid. A dynamic boundary layer based neural network quasi-sliding mode control law is proposed to track a desired descending path. The asteroid's gravitational acceleration acting on the spacecraft is described by the polyhedron method. Considering the presence of input constraint and unmodeled acceleration, the dynamic equation of relative motion is presented first. The desired descending path is planned using cubic polynomial method, and a collision detection algorithm is designed. To perform trajectory tracking, a neural network sliding mode control law is given first, where the sliding mode control is used to ensure the convergence of system states. Two radial basis function neural networks (RBFNNs) are respectively used as an approximator for the unmodeled term and a compensator for the difference between the actual control input with magnitude constraint and nominal control. To improve the chattering induced by the traditional sliding mode control and guarantee the reachability of the system, a specific saturation function with dynamic boundary layer is proposed to replace the sign function in the preceding control law. Through the Lyapunov approach, the reachability condition of the control system is given. The improved control law can guarantee the system state move within a gradually shrinking quasi-sliding mode band. Numerical simulation results demonstrate the effectiveness of the proposed control strategy.
NASA Astrophysics Data System (ADS)
Fleischhauer, F.; Feuchter, T.; Leick, L.; Rajendram, R.; Podoleanu, A.
2018-03-01
Spectroscopic spectral domain interferometry and spectroscopic optical coherence tomography combine depth information with spectrally-resolved localised absorption data. These additional data can improve diagnostics by giving access to functional information of the investigated sample. One possible application is measuring oxygenation levels at the retina for earlier detection of several eye diseases. Here measurements with different hollow glass tube phantoms are shown to measure the impact of a superficial absorbing layer on the precision of reconstructed attenuation spectra of a deeper layer. Measurements show that a superficial absorber has no impact on the reconstructed absorption spectrum of the deeper absorber. Even when diluting the concentration of the deeper absorber so far that an incorrect absorption maximum is obtained, still no influence of the superficially placed absorber is identified.
Hassan, Sehar-un-Nisa; Siddiqui, Salma; Mahmood, Ayeshah
2015-01-01
Background and Objective: Fertility control preferences and maternal healthcare have recently become a major concern for developing nations with evidence suggesting that low fertility control rates and poor maternal healthcare are among major obstructions in ensuring health and social status for women. Our objective was toanalyze the factors that influence women’s autonomy, access to maternal healthcare, and fertility control preferences in Pakistan. Methods: Data consisted of 11,761 ever-married women of ages 15-49 years from PDHS, 2012-13. Variables included socio-demographics, women’s autonomy, fertility control preferences and access to maternal healthcare. Results: Findings from multivariate analysis showed that women’s younger age, having less than three number of children and independent or joint decision-making (indicators of high autonomy) remained the most significant predictors for access to better quality maternal healthcare and better fertility control preferences when other variables were controlled. Conclusion: Women’s access to good quality maternal health care and fertility control preferences are directly and indirectly influenced by their demographic characteristics and decision-making patterns in domestic affairs. PMID:26870096
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.
Sforzo, Gary A; Kaye, Miranda P; Calleri, David; Ngai, Nancy
2012-04-01
Examine effects of voluntary participation in employer-sponsored, multipoint wellness education programming on employee wellness. A randomized and controlled design was used to organize 96 participants into an education + access group; an access-only group, and control group. Outcome measures were made at start and end of a 12-week intervention period. Education + access improved wellness knowledge, which, in turn, enhanced life satisfaction, employee morale, and energy, and nearly improved stress level. Those who received facility access without educational programming did not reap health benefits. Employees voluntarily used the fitness facility and healthy meal cards only 1.3 and 1.5 times per week, respectively. Participants made limited and likely inadequate use of wellness opportunities. As a result, physical health benefits (eg, blood pressure, fitness parameters) were not seen in the present study. However, multipoint wellness education resulted in psychosocial health benefits in 12 weeks.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ramalingam, Balavinayagam; Zheng, Haisheng; Gangopadhyay, Shubhra, E-mail: gangopadhyays@missouri.edu
In this work, we demonstrate multi-level operation of a non-volatile memory metal oxide semiconductor capacitor by controlled layer-by-layer charging of platinum nanoparticle (PtNP) floating gate devices with defined gate voltage bias ranges. The device consists of two layers of ultra-fine, sub-2 nm PtNPs integrated between Al{sub 2}O{sub 3} tunneling and separation layers. PtNP size and interparticle distance were varied to control the particle self-capacitance and associated Coulomb charging energy. Likewise, the tunneling layer thicknesses were also varied to control electron tunneling to the first and second PtNP layers. The final device configuration with optimal charging behavior and multi-level programming was attainedmore » with a 3 nm Al{sub 2}O{sub 3} initial tunneling layer, initial PtNP layer with particle size 0.54 ± 0.12 nm and interparticle distance 4.65 ± 2.09 nm, 3 nm Al{sub 2}O{sub 3} layer to separate the PtNP layers, and second particle layer with 1.11 ± 0.28 nm PtNP size and interparticle distance 2.75 ± 1.05 nm. In this device, the memory window of the first PtNP layer saturated over a programming bias range of 7 V to 14 V, after which the second PtNP layer starts charging, exhibiting a multi-step memory window with layer-by-layer charging.« less
Protecting Files Hosted on Virtual Machines With Out-of-Guest Access Control
2017-12-01
analyzes the design and methodology of the implemented mechanism, while Chapter 4 explains the test methodology, test cases, and performance testing ...SACL, we verify that the user or group accessing the file has sufficient permissions. If that is correct, the callback function returns control to...ferify. In the first section, we validate our design of ferify. Next, we explain the tests we performed to verify that ferify has the results we expected
NASA Astrophysics Data System (ADS)
Danilova, Olga; Semenova, Zinaida
2018-04-01
The objective of this study is a detailed analysis of physical protection systems development for information resources. The optimization theory and decision-making mathematical apparatus is used to formulate correctly and create an algorithm of selection procedure for security systems optimal configuration considering the location of the secured object’s access point and zones. The result of this study is a software implementation scheme of decision-making system for optimal placement of the physical access control system’s elements.
Understanding Micro-Ramp Control for Shock Boundary Layer Interactions
2008-02-07
micro-ramps on a supersonic boundary layer at M=3.0 was investigated using monotone integrated Large Eddy Simulations (MILES) and Reynolds Averaged Navier... Supersonic boundary layer flow with micro-ramp and no shock wave 3.2 SBLI with no micro-ramp 3.3 SBLI with micro-ramp 3.4 Micro-ramp size and location IV . C...ramps on a supersonic boundary layer at M=3.0 was investigated using monotone integrated Large Eddy Simulations (MILES) and Reynolds Averaged Navier
A review on transport layer protocol performance for delivering video on an adhoc network
NASA Astrophysics Data System (ADS)
Suherman; Suwendri; Al-Akaidi, Marwan
2017-09-01
The transport layer protocol is responsible for the end to end data transmission. Transmission control protocol (TCP) provides a reliable connection and user datagram protocol (UDP) offers fast but unguaranteed data transfer. Meanwhile, the 802.11 (wireless fidelity/WiFi) networks have been widely used as internet hotspots. This paper evaluates TCP, TCP variants and UDP performances for video transmission on an adhoc network. The transport protocol - medium access cross-layer is proposed by prioritizing TCP acknowledgement to reduce delay. The NS-2 evaluations show that the average delays increase linearly for all the evaluated protocols and the average packet losses grow logarithmically. UDP produces the lowest transmission delay; 5.4% and 5.8% lower than TCP and TCP variant, but experiences the highest packet loss. Both TCP and TCP Vegas maintain packet loss as low as possible. The proposed cross-layer successfully decreases TCP and TCP Vegas delay about 0.12 % and 0.15%, although losses remain similar.
Liu, Caihong; Lee, Jongho; Ma, Jun; Elimelech, Menachem
2017-02-21
In this study, we demonstrate a highly antifouling thin-film composite (TFC) membrane by grafting a zwitterionic polymer brush via atom-transfer radical-polymerization (ATRP), a controlled, environmentally benign chemical process. Initiator molecules for polymerization were immobilized on the membrane surface by bioinspired catechol chemistry, leading to the grafting of a dense zwitterionic polymer brush layer. Surface characterization revealed that the modified membrane exhibits reduced surface roughness, enhanced hydrophilicity, and lower surface charge. Chemical force microscopy demonstrated that the modified membrane displayed foulant-membrane interaction forces that were 1 order of magnitude smaller than those of the pristine TFC membrane. The excellent fouling resistance imparted by the zwitterionic brush layer was further demonstrated by significantly reduced adsorption of proteins and bacteria. In addition, forward osmosis fouling experiments with a feed solution containing a mixture of organic foulants (bovine-serum albumin, alginate, and natural organic matter) indicated that the modified membrane exhibited significantly lower water flux decline compared to the pristine TFC membrane. The controlled architecture of the zwitterionic polymer brush via ATRP has the potential for a facile antifouling modification of a wide range of water treatment membranes without compromising intrinsic transport properties.
Layer-controllable graphene by plasma thinning and post-annealing
NASA Astrophysics Data System (ADS)
Zhang, Lufang; Feng, Shaopeng; Xiao, Shaoqing; Shen, Gang; Zhang, Xiumei; Nan, Haiyan; Gu, Xiaofeng; Ostrikov, Kostya (Ken)
2018-05-01
The electronic structure of graphene depends crucially on its layer number and therefore engineering the number of graphene's atomic stacking layers is of great importance for the preparation of graphene-based devices. In this paper, we demonstrated a relatively less invasive, high-throughput and uniform large-area plasma thinning of graphene based on direct bombardment effect of fast-moving ionic hydrogen or argon species. Any desired number of graphene layers including trilayer, bilayer and monolayer can be obtained. Structural changes of graphene layers are studied by optical microscopy, Raman spectroscopy and atomic force microscopy. Post annealing is adopted to self-heal the lattice defects induced by the ion bombardment effect. This plasma etching technique is efficient and compatible with semiconductor manufacturing processes, and may find important applications for graphene-based device fabrication.
Controlled Synthesis of Atomically Layered Hexagonal Boron Nitride via Chemical Vapor Deposition.
Liu, Juanjuan; Kutty, R Govindan; Liu, Zheng
2016-11-29
Hexagonal boron nitrite (h-BN) is an attractive material for many applications including electronics as a complement to graphene, anti-oxidation coatings, light emitters, etc. However, the synthesis of high-quality h-BN is still a great challenge. In this work, via controlled chemical vapor deposition, we demonstrate the synthesis of h-BN films with a controlled thickness down to atomic layers. The quality of as-grown h-BN is confirmed by complementary characterizations including high-resolution transition electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray photo-electron spectroscopy. This work will pave the way for production of large-scale and high-quality h-BN and its applications as well.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kizu, Takio, E-mail: KIZU.Takio@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Tsukagoshi, Kazuhito, E-mail: KIZU.Takio@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Aikawa, Shinya
We fabricated homogeneous double-layer amorphous Si-doped indium oxide (ISO) thin-film transistors (TFTs) with an insulating ISO cap layer on top of a semiconducting ISO bottom channel layer. The homogeneously stacked ISO TFT exhibited high mobility (19.6 cm{sup 2}/V s) and normally-off characteristics after annealing in air. It exhibited normally-off characteristics because the ISO insulator suppressed oxygen desorption, which suppressed the formation of oxygen vacancies (V{sub O}) in the semiconducting ISO. Furthermore, we investigated the recovery of the double-layer ISO TFT, after a large negative shift in turn-on voltage caused by hydrogen annealing, by treating it with annealing in ozone. The recoverymore » in turn-on voltage indicates that the dense V{sub O} in the semiconducting ISO can be partially filled through the insulator ISO. Controlling molecule penetration in the homogeneous double layer is useful for adjusting the properties of TFTs in advanced oxide electronics.« less
NASA Technical Reports Server (NTRS)
Hultgren, Lennart S.; Ashpis, David E.
2003-01-01
Modem low-pressure turbines, in general, utilize highly loaded airfoils in an effort to improve efficiency and to lower the number of airfoils needed. Typically, the airfoil boundary layers are turbulent and fully attached at takeoff conditions, whereas a substantial fraction of the boundary layers on the airfoils may be transitional at cruise conditions due to the change of density with altitude. The strong adverse pressure gradients on the suction side of these airfoils can lead to boundary-layer separation at the latter low Reynolds number conditions. Large separation bubbles, particularly those which fail to reattach, cause a significant degradation of engine efficiency. A component efficiency drop of the order 2% may occur between takeoff and cruise conditions for large commercial transport engines and could be as large as 7% for smaller engines at higher altitude. An efficient means of of separation elimination/reduction is, therefore, crucial to improved turbine design. Because the large change in the Reynolds number from takeoff to cruise leads to a distinct change in the airfoil flow physics, a separation control strategy intended for cruise conditions will need to be carefully constructed so as to incur minimum impact/penalty at takeoff. A complicating factor, but also a potential advantage in the quest for an efficient strategy, is the intricate interplay between separation and transition for the situation at hand. Volino gives a comprehensive discussion of several recent studies on transition and separation under low-pressure-turbine conditions, among them one in the present facility. Transition may begin before or after separation, depending on the Reynolds number and other flow conditions. If the transition occurs early in the boundary layer then separation may be reduced or completely eliminated. Transition in the shear layer of a separation bubble can lead to rapid reattachment. This suggests using control mechanisms to trigger and enhance early
NASA Astrophysics Data System (ADS)
Impemba, Ernesto; Inzerilli, Tiziano
2003-07-01
Integration of satellite access networks with the Internet is seen as a strategic goal to achieve in order to provide ubiquitous broadband access to Internet services in Next Generation Networks (NGNs). One of the main interworking aspects which has been most studied is an efficient management of satellite resources, i.e. bandwidth and buffer space, in order to satisfy most demanding application requirements as to delay control and bandwidth assurance. In this context, resource management in DVB-S/DVB-RCS satellite technologies, emerging technologies for broadband satellite access and transport of IP applications, is a research issue largely investigated as a means to provide efficient bi-directional communications across satellites. This is in particular one of the principal goals of the SATIP6 project, sponsored within the 5th EU Research Programme Framework, i.e. IST. In this paper we present a possible approach to efficiently exploit bandwidth, the most critical resource in a broadband satellite access network, while pursuing satisfaction of delay and bandwidth requirements for applications with guaranteed QoS through a traffic control architecture to be implemented in ground terminals. Performance of this approach is assessed in terms of efficient exploitation of the uplink bandwidth and differentiation and minimization of queuing delays for most demanding applications over a time-varying capacity. Opnet simulations is used as analysis tool.
Extending the Ground Force Network: Aerial Layer Networking
2013-04-25
Additionally aerial layer networks are envisioned to augment the Global Information Grid ( GIG ) access, which is currently provided by the surface...frequencies such as HF, VHF, and UHF. This enabled ground forces to establish tactical wide area networks (WAN) and permitted entry to the GIG ...PRC-117G. Both systems are unique in their overall mission sets, but both provide tactical users access to the WAN and GIG . Self-forming and self
Control of the inversion-channel MOS properties by Mg doping in homoepitaxial p-GaN layers
NASA Astrophysics Data System (ADS)
Takashima, Shinya; Ueno, Katsunori; Matsuyama, Hideaki; Inamoto, Takuro; Edo, Masaharu; Takahashi, Tokio; Shimizu, Mitsuaki; Nakagawa, Kiyokazu
2017-12-01
Lateral GaN MOSFETs on homoepitaxial p-GaN layers with different Mg doping concentrations ([Mg]) have been evaluated to investigate the impact of [Mg] on MOS channel properties. It is demonstrated that the threshold voltage (V th) can be controlled by [Mg] along with the theoretical curve. The field effect mobility also shows [Mg] dependence and a maximum field effect mobility of 123 cm2 V-1 s-1 is achieved on [Mg] = 6.5 × 1016 cm-3 layer with V th = 3.0 V. The obtained results indicate that GaN MOSFETs can be designed on the basis of the doping concentration of the p-GaN layer with promising characteristics for the realization of power MOSFETs.
NASA Astrophysics Data System (ADS)
Jeong, Eun Sook; Kim, Jin Woong
2015-03-01
Hydrogel particles, also known as microgels, consist of cross-linked three-dimensional water-soluble polymer networks. They play an essential role in loading and delivering active ingredients in medicine, cosmetics, and foods. Despite their excellent biocompatibility as well as structural diversity, much wider applications are limited due mainly to their intrinsically loose network nature. This study introduces a practical and straightforward method that enables fabrication of hydrogel microparticles layered with a mechanically robust hybrid thin shell. Basically highly monodisperse hydrogel microparticles were produced in microcapillary devices. Then, their surface was coated with alternate polyelectrolyte layers through the layer-by-layer deposition. Finally a thin silica layer was again formed by reduction of silicate on the amino-functionalized polyelectrolyte layer. We have figured out that these hybrid hydrogel microparticles showed controlled loading and releasing behaviors for water-soluble probe molecules. Moreover, we have demonstrated that they can be applied for immobilization of biomacromolecules, such as bacteria and living cells, and even for targeted releasing.
Scrape-off-layer characterization and current-control of kink modes in HBT-EP
NASA Astrophysics Data System (ADS)
Brooks, John; Stewart, Ian; Levesque, Jeffrey; Mauel, Mike; Navratil, Gerald
2017-10-01
Scrape-off layer (SOL) currents and their paths through tokamaks are not well understood, but their control may prove crucial to the success of ITER and future fusion energy devices. We extend Columbia University's High Beta Tokamak-Extended Pulse (HBT-EP) experiment and active GPU feedback system to study the SOL and control MHD kink instabilities by actively controlling these currents. First, the radial plasma profiles and the edge structure of kink instabilities are measured with two triple probes. Second, we use active feedback control of a radially adjustable biased electrode to change the rotation and magnitude of slowly growing kink instabilities. By changing the phase between the probe's voltage and the edge instability with active feedback, we study its ability to influence and control plasma MHD structures. This work is in preparation for a planned 2018 multi-electrode SOL control upgrade. Supported by U.S. DOE Grant DE-FG02-86ER53222.
Dereymaker, Aswin; Scurr, David J; Steer, Elisabeth D; Roberts, Clive J; Van den Mooter, Guy
2017-04-03
Fluid bed coating has been shown to be a suitable manufacturing technique to formulate poorly soluble drugs in glass solutions. Layering inert carriers with a drug-polymer mixture enables these beads to be immediately filled into capsules, thus avoiding additional, potentially destabilizing, downstream processing. In this study, fluid bed coating is proposed for the production of controlled release dosage forms of glass solutions by applying a second, rate controlling membrane on top of the glass solution. Adding a second coating layer adds to the physical and chemical complexity of the drug delivery system, so a thorough understanding of the physical structure and phase behavior of the different coating layers is needed. This study aimed to investigate the surface and cross-sectional characteristics (employing scanning electron microscopy (SEM) and time of flight secondary ion mass spectrometry (ToF-SIMS)) of an indomethacin-polyvinylpyrrolidone (PVP) glass solution, top-coated with a release rate controlling membrane consisting of either ethyl cellulose or Eudragit RL. The implications of the addition of a pore former (PVP) and the coating medium (ethanol or water) were also considered. In addition, polymer miscibility and the phase analysis of the underlying glass solution were investigated. Significant differences in surface and cross-sectional topography of the different rate controlling membranes or the way they are applied (solution vs dispersion) were observed. These observations can be linked to the polymer miscibility differences. The presence of PVP was observed in all rate controlling membranes, even if it is not part of the coating solution. This could be attributed to residual powder presence in the coating chamber. The distribution of PVP among the sample surfaces depends on the concentration and the rate controlling polymer used. Differences can again be linked to polymer miscibility. Finally, it was shown that the underlying glass solution layer
NASA Astrophysics Data System (ADS)
Duff, Francis; McGarry, Donald; Zasada, David; Foote, Scott
2009-05-01
The MITRE Sensor Layer Prototype is an initial design effort to enable every sensor to help create new capabilities through collaborative data sharing. By making both upstream (raw) and downstream (processed) sensor data visible, users can access the specific level, type, and quantities of data needed to create new data products that were never anticipated by the original designers of the individual sensors. The major characteristic that sets sensor data services apart from typical enterprise services is the volume (on the order of multiple terabytes) of raw data that can be generated by most sensors. Traditional tightly coupled processing approaches extract pre-determined information from the incoming raw sensor data, format it, and send it to predetermined users. The community is rapidly reaching the conclusion that tightly coupled sensor processing loses too much potentially critical information.1 Hence upstream (raw and partially processed) data must be extracted, rapidly archived, and advertised to the enterprise for unanticipated uses. The authors believe layered sensing net-centric integration can be achieved through a standardize-encapsulate-syndicateaggregate- manipulate-process paradigm. The Sensor Layer Prototype's technical approach focuses on implementing this proof of concept framework to make sensor data visible, accessible and useful to the enterprise. To achieve this, a "raw" data tap between physical transducers associated with sensor arrays and the embedded sensor signal processing hardware and software has been exploited. Second, we encapsulate and expose both raw and partially processed data to the enterprise within the context of a service-oriented architecture. Third, we advertise the presence of multiple types, and multiple layers of data through geographic-enabled Really Simple Syndication (GeoRSS) services. These GeoRSS feeds are aggregated, manipulated, and filtered by a feed aggregator. After filtering these feeds to bring just the type
Vierhout, Bastiaan P; Saleem, Ben R; Ott, Alewijn; van Dijl, Jan Maarten; de Kempenaer, Ties D van Andringa; Pierie, Maurice E N; Bottema, Jan T; Zeebregts, Clark J
2015-09-14
Access for endovascular repair of abdominal aortic aneurysms (EVAR) is obtained through surgical cutdown or percutaneously. The only devices suitable for percutaneous closure of the 20 French arteriotomies of the common femoral artery (CFA) are the Prostar(™) and Proglide(™) devices (Abbott Vascular). Positive effects of these devices seem to consist of a lower infection rate, and shorter operation time and hospital stay. This conclusion was published in previous reports comparing techniques in patients in two different groups (cohort or randomized). Access techniques were never compared in one and the same patient; this research simplifies comparison because patient characteristics will be similar in both groups. Percutaneous access of the CFA is compared to surgical cutdown in a single patient; in EVAR surgery, access is necessary in both groins in each patient. Randomization is performed on the introduction site of the larger main device of the endoprosthesis. The contralateral device of the endoprosthesis is smaller. When we use this type of randomization, both groups will contain a similar number of main and contralateral devices. Preoperative nose cultures and perineal cultures are obtained, to compare colonization with postoperative wound cultures (in case of a surgical site infection). Furthermore, patient comfort will be considered, using VAS-scores (Visual analog scale). Punch biopsies of the groin will be harvested to retrospectively compare skin of patients who suffered a surgical site infection (SSI) to patients who did not have an SSI. The PiERO trial is a multicenter randomized controlled clinical trial designed to show the consequences of using percutaneous access in EVAR surgery and focuses on the occurrence of surgical site infections. NTR4257 10 November 2013, NL44578.042.13.
Stability of organic carbon in deep soil layers controlled by fresh carbon supply.
Fontaine, Sébastien; Barot, Sébastien; Barré, Pierre; Bdioui, Nadia; Mary, Bruno; Rumpel, Cornelia
2007-11-08
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.
In-situ photoluminescence imaging for passivation-layer etching process control for photovoltaics
NASA Astrophysics Data System (ADS)
Lee, J. Z.; Michaelson, L.; Munoz, K.; Tyson, T.; Gallegos, A.; Sullivan, J. T.; Buonassisi, T.
2014-07-01
Light-induced plating (LIP) of solar-cell metal contacts is a scalable alternative to silver paste. However, LIP requires an additional patterning step to create openings in the silicon nitride (SiNx) antireflection coating (ARC) layer prior to metallization. One approach to pattern the SiNx is masking and wet chemical etching. In-situ real-time photoluminescence imaging (PLI) is demonstrated as a process-monitoring method to determine when SiNx has been fully removed during etching. We demonstrate that the change in PLI signal intensity during etching is caused by a combination of (1) decreasing light absorption from the reduction in SiNx ARC layer thickness and (2) decreasing surface lifetime as the SiNx/Si interface transitions to an etch-solution/Si. Using in-situ PLI to guide the etching process, we demonstrate a full-area plated single-crystalline silicon device. In-situ PLI has the potential to be integrated into a commercial processing line to improve process control and reliability.
Federal Register 2010, 2011, 2012, 2013, 2014
2011-12-20
... initiated a rulemaking proceeding in accordance with provisions added by the Digital Millennium Copyright... available in digital copies. Proponent: The Open Book Alliance. 2. Literary works, distributed electronically, that: (1) Contain digital rights management and/or other access controls which either prevent the...
Federal Register 2010, 2011, 2012, 2013, 2014
2010-08-06
... LIBRARY OF CONGRESS Copyright Office 37 CFR Part 201 [Docket No. RM 2008-8] 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...
Jiang, Youyu; Xiao, Shengqiang; Xu, Biao; Zhan, Chun; Mai, Liqiang; Lu, Xinhui; You, Wei
2016-05-11
Herein, a successful application of V2O5·nH2O film as hole transporting layer (HTL) instead of PSS in polymer solar cells is demonstrated. The V2O5·nH2O layer was spin-coated from V2O5·nH2O sol made from melting-quenching sol-gel method by directly using vanadium oxide powder, which is readily accessible and cost-effective. V2O5·nH2O (n ≈ 1) HTL is found to have comparable work function and smooth surface to that of PSS. For the solar cell containing V2O5·nH2O HTL and the active layer of the blend of a novel polymer donor (PBDSe-DT2PyT) and the acceptor of PC71BM, the PCE was significantly improved to 5.87% with a 30% increase over 4.55% attained with PSS HTL. Incorporation of V2O5·nH2O as HTL in the polymer solar cell was found to enhance the crystallinity of the active layer, electron-blocking at the anode and the light-harvest in the wavelength range of 400-550 nm in the cell. V2O5·nH2O HTL improves the charge generation and collection and suppress the charge recombination within the PBDSe-DT2PyT:PC71BM solar cell, leading to a simultaneous enhancement in Voc, Jsc, and FF. The V2O5·nH2O HTL proposed in this work is envisioned to be of great potential to fabricate highly efficient PSCs with low-cost and massive production.
Access management for Kentucky.
DOT National Transportation Integrated Search
2004-02-01
The Access Management Manual published by the Transportation Research Board in 2003 defines access management as the "systematic control of the location, spacing, design, and operation of driveways, median openings, interchanges, and street connectio...
Controlled Synthesis of Pd/Pt Core Shell Nanoparticles Using Area-selective Atomic Layer Deposition
Cao, Kun; Zhu, Qianqian; Shan, Bin; Chen, Rong
2015-01-01
We report an atomic scale controllable synthesis of Pd/Pt core shell nanoparticles (NPs) via area-selective atomic layer deposition (ALD) on a modified surface. The method involves utilizing octadecyltrichlorosilane (ODTS) self-assembled monolayers (SAMs) to modify the surface. Take the usage of pinholes on SAMs as active sites for the initial core nucleation, and subsequent selective deposition of the second metal as the shell layer. Since new nucleation sites can be effectively blocked by surface ODTS SAMs in the second deposition stage, we demonstrate the successful growth of Pd/Pt and Pt/Pd NPs with uniform core shell structures and narrow size distribution. The size, shell thickness and composition of the NPs can be controlled precisely by varying the ALD cycles. Such core shell structures can be realized by using regular ALD recipes without special adjustment. This SAMs assisted area-selective ALD method of core shell structure fabrication greatly expands the applicability of ALD in fabricating novel structures and can be readily applied to the growth of NPs with other compositions. PMID:25683469
Application of sound and temperature to control boundary-layer transition
NASA Technical Reports Server (NTRS)
Maestrello, Lucio; Parikh, Paresh; Bayliss, A.; Huang, L. S.; Bryant, T. D.
1987-01-01
The growth and decay of a wave packet convecting in a boundary layer over a concave-convex surface and its active control by localized surface heating are studied numerically using direct computations of the Navier-Stokes equations. The resulting sound radiations are computed using linearized Euler equations with the pressure from the Navier-Stokes solution as a time-dependent boundary condition. It is shown that on the concave portion the amplitude of the wave packet increases and its bandwidth broadens while on the convex portion some of the components in the packet are stabilized. The pressure field decays exponentially away from the surface and then algebraically, exhibiting a decay characteristic of acoustic waves in two dimensions. The far-field acoustic behavior exhibits a super-directivity type of behavior with a beaming downstream. Active control by surface heating is shown to reduce the growth of the wave packet but have little effect on acoustic far field behavior for the cases considered. Active control by sound emanating from the surface of an airfoil in the vicinity of the leading edge is experimentally investigated. The purpose is to control the separated region at high angles of attack. The results show that injection of sound at shedding frequency of the flow is effective in an increase of lift and reduction of drag.
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.
On the designing of a tamper resistant prescription RFID access control system.
Safkhani, Masoumeh; Bagheri, Nasour; Naderi, Majid
2012-12-01
Recently, Chen et al. have proposed a novel tamper resistant prescription RFID access control system, published in the Journal of Medical Systems. In this paper we consider the security of the proposed protocol and identify some existing weaknesses. The main attack is a reader impersonation attack which allows an active adversary to impersonate a legitimate doctor, e.g. the patient's doctor, to access the patient's tag and change the patient prescription. The presented attack is quite efficient. To impersonate a doctor, the adversary should eavesdrop one session between the doctor and the patient's tag and then she can impersonate the doctor with the success probability of '1'. In addition, we present efficient reader-tag to back-end database impersonation, de-synchronization and traceability attacks against the protocol. Finally, we propose an improved version of protocol which is more efficient compared to the original protocol while provides the desired security against the presented attacks.
Underpotential deposition-mediated layer-by-layer growth of thin films
Wang, Jia Xu; Adzic, Radoslav R.
2017-06-27
A method of depositing contiguous, conformal submonolayer-to-multilayer thin films with atomic-level control is described. The process involves electrochemically exchanging a mediating element on a substrate with a noble metal film by alternatingly sweeping potential in forward and reverse directions for a predetermined number of times in an electrochemical cell. By cycling the applied voltage between the bulk deposition potential for the mediating element and the material to be deposited, repeated desorption/adsorption of the mediating element during each potential cycle can be used to precisely control film growth on a layer-by-layer basis.
Polymer mediated layer-by-layer assembly of different shaped gold nanoparticles.
Budy, Stephen M; Hamilton, Desmond J; Cai, Yuheng; Knowles, Michelle K; Reed, Scott M
2017-02-01
Gold nanoparticles (GNPs) have a wide range of properties with potential applications in electronics, optics, catalysis, and sensing. In order to demonstrate that dense, stable, and portable samples could be created for these applications, multiple layers of GNPs were assembled via drop casting on glass substrates by layer-by-layer (LBL) techniques. Two cationic polyelectrolytes, poly(diallyldimethylammonium chloride) and polyethyleneimine, one anionic polyelectrolyte, poly(sodium 4-styrene sulfonate), and one neutral polymer, polyvinylpyrrolidone, were combined with four different shapes of GNPs (spherical, rod, triangular prismatic, and octahedral) to prepare thin films. A subset of these polymer nanoparticle combinations were assembled into thin films. Synthesized GNPs were characterized via dynamic light scattering, UV-vis spectroscopy, and transmission electron microscopy and the LBL thin films were characterized using UV-vis spectroscopy and atomic force microscopy. Sensing applications of the nanoparticles in solution and thin films were tested by monitoring the localized surface plasmon resonance of the GNPs. LBL thin films were prepared ranging from 25 to 100 layers with optical densities at plasmon from 0.5 to 3.0. Sensitivity in solutions ranged from 14 to 1002nm/refractive index units (RIU) and films ranged from 18.8 to 135.1nm/RIU suggesting reduced access to the GNPs within the films. Copyright © 2016 Elsevier Inc. All rights reserved.
DOT National Transportation Integrated Search
1972-12-01
The purpose of the diagrammatic signing research project was to develop warrants and standards for the use of diagrammatic guide signs on controlled access highways. Volume 1 summarizes the entire diagrammatic signing research program objectives spon...
NASA Astrophysics Data System (ADS)
Murata, H.; Saitoh, N.; Yoshizawa, N.; Suemasu, T.; Toko, K.
2017-12-01
The Ni-induced layer-exchange growth of amorphous carbon is a unique method used to fabricate uniform multilayer graphene (MLG) directly on an insulator. To improve the crystal quality of MLG, we prepare AlOx or SiO2 interlayers between amorphous C and Ni layers, which control the extent of diffusion of C atoms into the Ni layer. The growth morphology and Raman spectra observed from MLG formed by layer exchange strongly depend on the material type and thickness of the interlayers; a 1-nm-thick AlOx interlayer is found to be ideal for use in experiments. Transmission electron microscopy and electron energy-loss spectra reveal that the crystal quality of the resulting MLG is much higher than that of a sample without an interlayer. The grain size reaches a few μm, leading to an electrical conductivity of 1290 S/cm. The grain size and the electrical conductivity are the highest among MLG synthesized using a solid-phase reaction including metal-induced crystallization. The direct synthesis of uniform, high-quality MLG on arbitrary substrates will pave the way for advanced electronic devices integrated with carbon materials.
NASA Astrophysics Data System (ADS)
Han, Tae-Hee; Kwon, Sung-Joo; Seo, Hong-Kyu; Lee, Tae-Woo
2016-03-01
Ultraviolet ozone (UVO) surface treatment of graphene changes its sp2-hybridized carbons to sp3-bonded carbons, and introduces oxygen-containing components. Oxidized graphene has a finite energy band gap, so UVO modification of the surface of a four-layered graphene anode increases its surface ionization potential up to ∼5.2 eV and improves the hole injection efficiency (η) in organic electronic devices by reducing the energy barrier between the graphene anode and overlying organic layers. By controlling the conditions of the UVO treatment, the electrical properties of the graphene can be tuned to improve η. This controlled surface modification of the graphene will provide a way to achieve efficient and stable flexible displays and solid-state lighting.
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…
Wang, Yifeng; Zhou, Jing; Guo, Xuecheng; Hu, Qian; Qin, Chaoran; Liu, Hui; Dong, Meng; Chen, Yanjun
2017-12-01
In this work, a layer-by-layer (LbL) assembled biopolymer microcapsule with separate layer cavities is generated by a novel and convenient gas-liquid microfluidic approach. This approach exhibits combined advantages of microfluidic approach and LbL assembly method, and it can straightforwardly build LbL-assembled capsules in mild aqueous environments at room temperature. In particular, using this approach we can build the polyelectrolyte multilayer capsule with favorable cavities in each layer, and without the need for organic solvent, emulsifying agent, or sacrificial template. Various components (e.g., drugs, proteins, fluorescent dyes, and nanoparticles) can be respectively encapsulated in the separate layer cavities of the LbL-assembled capsules. Moreover, the encapsulated capsules present the ability as colorimetric sensors, and they also exhibit the interesting release behavior. Therefore, the LbL-assembled biopolymer capsule is a promising candidate for biomedical applications in targeted delivery, controlled release, and bio-detection. Copyright © 2017 Elsevier B.V. All rights reserved.
Jahn-Schmid, B; Messner, P; Unger, F M; Sleytr, U B; Scheiner, O; Kraft, D
1996-01-26
Bacterial surface layer proteins have been utilized as combined vaccine carrier/adjuvants and offer a number of advantages in these applications. The crystalline protein arrays contain functional groups in precisely defined orientations for coupling of haptens. Conventional applications of S-layer vaccines do not cause observable trauma or side effects. Depending on the nature of the S-layer preparations, antigenic conjugates will induce immune responses of a predominantly cellular or predominantly humoral nature. Immune responses to S-layer-hapten conjugates are also observed following oral/nasal application. In the present contribution, the status of investigations with S-layer conjugates in three main immunological projects is reviewed. In a project aimed at immunotherapy of cancer, conjugates of S-layer with small, tumor-associated oligosaccharides have been found to elicit hapten-specific DTH responses. An enlarged program of chemical synthesis has now been initiated to prepare a complete set of mucin-derived, tumor-associated oligosaccharides and their chemically modified analogues for elicitation of cell-mediated immune responses to certain tumors in humans. In another application, oligosaccharides derived from capsules of Streptococcus pneumoniae type 8 have been linked to S-layer proteins and have been found to elicit protective antibody responses in animals. Most recently, allergen S-layer conjugates have been prepared with the intention to suppress the TH2-directed, IgE-mediated allergic responses to Bet nu 1, the major allergen of birch pollen. In the former two applications, the S-layer vaccine technology appears to offer the versatility needed to direct vaccination responses toward predominant control by TH1 or TH2 lymphocytes to meet the different therapeutic or prophylactic requirements in each case. In the third application, work has progressed to a preliminary stage only.
17 CFR 240.15c3-5 - Risk management controls for brokers or dealers with market access.
Code of Federal Regulations, 2011 CFR
2011-04-01
... determining that such customer, based on its position in the transaction and relationship with an ultimate... 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...
17 CFR 240.15c3-5 - Risk management controls for brokers or dealers with market access.
Code of Federal Regulations, 2012 CFR
2012-04-01
... determining that such customer, based on its position in the transaction and relationship with an ultimate... 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...
Layered video transmission over multirate DS-CDMA wireless systems
NASA Astrophysics Data System (ADS)
Kondi, Lisimachos P.; Srinivasan, Deepika; Pados, Dimitris A.; Batalama, Stella N.
2003-05-01
n this paper, we consider the transmission of video over wireless direct-sequence code-division multiple access (DS-CDMA) channels. A layered (scalable) video source codec is used and each layer is transmitted over a different CDMA channel. Spreading codes with different lengths are allowed for each CDMA channel (multirate CDMA). Thus, a different number of chips per bit can be used for the transmission of each scalable layer. For a given fixed energy value per chip and chip rate, the selection of a spreading code length affects the transmitted energy per bit and bit rate for each scalable layer. An MPEG-4 source encoder is used to provide a two-layer SNR scalable bitstream. Each of the two layers is channel-coded using Rate-Compatible Punctured Convolutional (RCPC) codes. Then, the data are interleaved, spread, carrier-modulated and transmitted over the wireless channel. A multipath Rayleigh fading channel is assumed. At the other end, we assume the presence of an antenna array receiver. After carrier demodulation, multiple-access-interference suppressing despreading is performed using space-time auxiliary vector (AV) filtering. The choice of the AV receiver is dictated by realistic channel fading rates that limit the data record available for receiver adaptation and redesign. Indeed, AV filter short-data-record estimators have been shown to exhibit superior bit-error-rate performance in comparison with LMS, RLS, SMI, or 'multistage nested Wiener' adaptive filter implementations. Our experimental results demonstrate the effectiveness of multirate DS-CDMA systems for wireless video transmission.
Zhou, Zehang; Panatdasirisuk, Weerapha; Mathis, Tyler S; Anasori, Babak; Lu, Canhui; Zhang, Xinxing; Liao, Zhiwei; Gogotsi, Yury; Yang, Shu
2018-03-29
Free-standing, highly flexible and foldable supercapacitor electrodes were fabricated through the spray-coating assisted layer-by-layer assembly of Ti3C2Tx (MXene) nanoflakes together with multi-walled carbon nanotubes (MWCNTs) on electrospun polycaprolactone (PCL) fiber networks. The open structure of the PCL network and the use of MWCNTs as spacers not only limit the restacking of Ti3C2Tx flakes but also increase the accessible surface of the active materials, facilitating fast diffusion of electrolyte ions within the electrode. Composite electrodes have areal capacitance (30-50 mF cm-2) comparable to other templated electrodes reported in the literature, but showed significantly improved rate performance (14-16% capacitance retention at a scan rate of 100 V s-1). Furthermore, the composite electrodes are flexible and foldable, demonstrating good tolerance against repeated mechanical deformation, including twisting and folding. Therefore, these tens of micron thick fiber electrodes will be attractive for applications in energy storage, electroanalytical chemistry, brain electrodes, electrocatalysis and other fields, where flexible freestanding electrodes with an open and accessible surface are highly desired.
33 CFR 105.255 - Security measures for access control.
Code of Federal Regulations, 2010 CFR
2010-07-01
... and facilities; (4) Granting access to only those responding to the security incident or threat... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Security measures for access... SECURITY MARITIME SECURITY MARITIME SECURITY: FACILITIES Facility Security Requirements § 105.255 Security...
Computer access security code system
NASA Technical Reports Server (NTRS)
Collins, Earl R., Jr. (Inventor)
1990-01-01
A security code system for controlling access to computer and computer-controlled entry situations comprises a plurality of subsets of alpha-numeric characters disposed in random order in matrices of at least two dimensions forming theoretical rectangles, cubes, etc., such that when access is desired, at least one pair of previously unused character subsets not found in the same row or column of the matrix is chosen at random and transmitted by the computer. The proper response to gain access is transmittal of subsets which complete the rectangle, and/or a parallelepiped whose opposite corners were defined by first groups of code. Once used, subsets are not used again to absolutely defeat unauthorized access by eavesdropping, and the like.
NASA Astrophysics Data System (ADS)
Yoon, Young Jun; Seo, Jae Hwa; Kang, In Man
2018-04-01
In this work, we present a capacitorless one-transistor dynamic random-access memory (1T-DRAM) based on an asymmetric double-gate Ge/GaAs-heterojunction tunneling field-effect transistor (TFET) for DRAM applications. The n-doped boosting layer and gate2 drain-underlap structure is employed in the device to obtain an excellent 1T-DRAM performance. The n-doped layer inserted between the source and channel regions improves the sensing margin because of a high rate of increase in the band-to-band tunneling (BTBT) probability. Furthermore, because the gate2 drain-underlap structure reduces the recombination rate that occurs between the gate2 and drain regions, a device with a gate2 drain-underlap length (L G2_D-underlap) of 10 nm exhibited a longer retention performance. As a result, by applying the n-doped layer and gate2 drain-underlap structure, the proposed device exhibited not only a high sensing margin of 1.11 µA/µm but also a long retention time of greater than 100 ms at a temperature of 358 K (85 °C).
Design and calibration of the mixing layer and wind tunnel
NASA Technical Reports Server (NTRS)
Bell, James H.; Mehta, Rabindra D.
1989-01-01
A detailed account of the design, assembly and calibration of a wind tunnel specifically designed for free-shear layer research is contained. The construction of this new facility was motivated by a strong interest in the study of plane mixing layers with varying initial and operating conditions. The Mixing Layer Wind tunnel is located in the Fluid Mechanics Laboratory at NASA Ames Research Center. The tunnel consists of two separate legs which are driven independently by centrifugal blowers connected to variable speed motors. The blower/motor combinations are sized such that one is smaller than the other, giving maximum flow speeds of about 20 and 40 m/s, respectively. The blower speeds can either be set manually or via the Microvax II computer. The two streams are allowed to merge in the test section at the sharp trailing edge of a slowly tapering splitter plate. The test section is 36 cm in the cross-stream direction, 91 cm in the spanwise direction and 366 cm in length. One test section side-wall is slotted for probe access and adjustable so that the streamwise pressure gradient may be controlled. The wind tunnel is also equipped with a computer controlled, three-dimensional traversing system which is used to investigate the flow fields with pressure and hot-wire instrumentation. The wind tunnel calibration results show that the mean flow in the test section is uniform to within plus or minus 0.25 pct and the flow angularity is less than 0.25 deg. The total streamwise free-stream turbulence intensity level is approximately 0.15 pct. Currently the wind tunnel is being used in experiments designed to study the three-dimensional structure of plane mixing layers and wakes.
Ellipsometric porosimetry on pore-controlled TiO2 layers
NASA Astrophysics Data System (ADS)
Rosu, Dana-Maria; Ortel, Erik; Hodoroaba, Vasile-Dan; Kraehnert, Ralph; Hertwig, Andreas
2017-11-01
The practical performance of surface coatings in applications like catalysis, water splitting or batteries depends critically on the coating materials' porosity. Determining the porosity in a fast and non-destructive way is still an unsolved problem for industrial thin-films technology. As a contribution to calibrated, non-destructive, optical layer characterisation, we present a multi-method comparison study on porous TiO2 films deposited by sol-gel synthesis on Si wafers. The ellipsometric data were collected on a range of samples with different TiO2 layer thickness and different porosity values. These samples were produced by templated sol-gel synthesis resulting in layers with a well-defined pore size and pore density. The ellipsometry measurement data were analysed by means of a Bruggeman effective medium approximation (BEMA), with the aim to determine the mixture ratio of void and matrix material by a multi-sample analysis strategy. This analysis yielded porosities and layer thicknesses for all samples as well as the dielectric function for the matrix material. Following the idea of multi-method techniques in metrology, the data was referenced to imaging by electron microscopy (SEM) and to a new EPMA (electron probe microanalysis) porosity approach for thin film analysis. This work might lead to a better metrological understanding of optical porosimetry and also to better-qualified characterisation methods for nano-porous layer systems.
Reduction of turbulent boundary layer induced interior noise through active impedance control.
Remington, Paul J; Curtis, Alan R D; Coleman, Ronald B; Knight, J Scott
2008-03-01
The use of a single actuator tuned to an optimum impedance to control the sound power radiated from a turbulent boundary layer (TBL) excited aircraft panel into the aircraft interior is examined. An approach to calculating the optimum impedance is defined and the limitations on the reduction in radiated power by a single actuator tuned to that impedance are examined. It is shown that there are too many degrees of freedom in the TBL and in the radiation modes of the panel to allow a single actuator to control the radiated power. However, if the panel modes are lightly damped and well separated in frequency, significant reductions are possible. The implementation of a controller that presents a desired impedance to a structure is demonstrated in a laboratory experiment, in which the structure is a mass. The performance of such a controller on an aircraft panel is shown to be effective, if the actuator impedance is similar to but not the same as the desired impedance, provided the panel resonances are well separated in frequency and lightly damped.
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... system provided by a broker-dealer operator of an alternative trading system to a non-broker-dealer. (2...
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... system provided by a broker-dealer operator of an alternative trading system to a non-broker-dealer. (2...
Surface Characterization of an Organized Titanium Dioxide Layer
NASA Astrophysics Data System (ADS)
Curtis, Travis
Soft lithographic printing techniques can be used to control the surface morphology of titanium dioxide layers on length scales of several hundred nanometers. Controlling surface morphology and volumetric organization of titanium dioxide electrodes can potentially be used in dye-sensitized solar cell devices. This thesis explores how layer-by-layer replication can lead to well defined, dimensionally controlled volumes and details how these control mechanisms influence surface characteristics of the semiconducting oxide.
Yoon, Doe Hyun; Muralimanohar, Naveen; Chang, Jichuan; Ranganthan, Parthasarathy
2017-09-26
A disclosed example method involves performing simultaneous data accesses on at least first and second independently selectable logical sub-ranks to access first data via a wide internal data bus in a memory device. The memory device includes a translation buffer chip, memory chips in independently selectable logical sub-ranks, a narrow external data bus to connect the translation buffer chip to a memory controller, and the wide internal data bus between the translation buffer chip and the memory chips. A data access is performed on only the first independently selectable logical sub-rank to access second data via the wide internal data bus. The example method also involves locating a first portion of the first data, a second portion of the first data, and the second data on the narrow external data bus during separate data transfers.
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.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Shen; Sina, Mahsa; Parikh, Pritesh
2016-09-14
Hybrid organic-inorganic materials for high efficiency, low cost photovoltaic devices have seen rapid progress since the introduction of lead based perovskites and solid-state hole transport layers. Although majority of the materials used for perovskite solar cells (PSC) are introduced from dye-sensitized solar cells (DSSCs), the presence of a perovskite capping layer as opposed to a single dye molecule (in DSSCs) changes the interactions between the various layers in perovskite solar cells. 4-tert-butylpyridine (tBP), commonly used in PSCs, is assumed to function as a charge recombination inhibitor, similar to DSSCs. However, the presence of a perovskite capping layer calls for amore » re-evaluation of its function in PSCs. Using TEM (transmission electron microscopy), we first confirm the role of tBP as a HTL morphology controller in PSCs. Our observations suggest that tBP significantly improves the uniformity of the HTL and avoids accumulation of Li salt. We also study degradation pathways by using FTIR (Fourier transform infrared spectroscopy) and APT (atom probe tomography) to investigate and visualize in 3-dimensions the moisture content associated with the Li salt. Long term effects, over 1000 hours, due to evaporation of tBP have also been studied. Based on our findings, a PSC failure mechanism associated with the morphological change of the HTL is proposed. tBP, the morphology controller in HTL, plays a key role in this process and thus this study highlights the need for additive materials with higher boiling points for consistent long term performance of PSCs.« less
Wang, Shen; Sina, Mahsa; Parikh, Pritesh; Uekert, Taylor; Shahbazian, Brian; Devaraj, Arun; Meng, Ying Shirley
2016-09-14
Hybrid organic-inorganic materials for high-efficiency, low-cost photovoltaic devices have seen rapid progress since the introduction of lead based perovskites and solid-state hole transport layers. Although majority of the materials used for perovskite solar cells (PSC) are introduced from dye-sensitized solar cells (DSSCs), the presence of a perovskite capping layer as opposed to a single dye molecule (in DSSCs) changes the interactions between the various layers in perovskite solar cells. 4-tert-Butylpyridine (tBP), commonly used in PSCs, is assumed to function as a charge recombination inhibitor, similar to DSSCs. However, the presence of a perovskite capping layer calls for a re-evaluation of its function in PSCs. Using TEM (transmission electron microscopy), we first confirm the role of tBP as a HTL morphology controller in PSCs. Our observations suggest that tBP significantly improves the uniformity of the HTL and avoids accumulation of Li salt. We also study degradation pathways by using FTIR (Fourier transform infrared spectroscopy) and APT (atom probe tomography) to investigate and visualize in 3-dimensions the moisture content associated with the Li salt. Long-term effects, over 1000 h, due to evaporation of tBP have also been studied. Based on our findings, a PSC failure mechanism associated with the morphological change of the HTL is proposed. tBP, the morphology controller in HTL, plays a key role in this process, and thus this study highlights the need for additive materials with higher boiling points for consistent long-term performance of PSCs.
Application of SQL database to the control system of MOIRCS
NASA Astrophysics Data System (ADS)
Yoshikawa, Tomohiro; Omata, Koji; Konishi, Masahiro; Ichikawa, Takashi; Suzuki, Ryuji; Tokoku, Chihiro; Uchimoto, Yuka Katsuno; Nishimura, Tetsuo
2006-06-01
MOIRCS (Multi-Object Infrared Camera and Spectrograph) is a new instrument for the Subaru telescope. In order to perform observations of near-infrared imaging and spectroscopy with cold slit mask, MOIRCS contains many device components, which are distributed on an Ethernet LAN. Two PCs wired to the focal plane array electronics operate two HAWAII2 detectors, respectively, and other two PCs are used for integrated control and quick data reduction, respectively. Though most of the devices (e.g., filter and grism turrets, slit exchange mechanism for spectroscopy) are controlled via RS232C interface, they are accessible from TCP/IP connection using TCP/IP to RS232C converters. Moreover, other devices are also connected to the Ethernet LAN. This network distributed structure provides flexibility of hardware configuration. We have constructed an integrated control system for such network distributed hardwares, named T-LECS (Tohoku University - Layered Electronic Control System). T-LECS has also network distributed software design, applying TCP/IP socket communication to interprocess communication. In order to help the communication between the device interfaces and the user interfaces, we defined three layers in T-LECS; an external layer for user interface applications, an internal layer for device interface applications, and a communication layer, which connects two layers above. In the communication layer, we store the data of the system to an SQL database server; they are status data, FITS header data, and also meta data such as device configuration data and FITS configuration data. We present our software system design and the database schema to manage observations of MOIRCS with Subaru.
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