Induced migration of fines during waterflooding in communicating layer-cake reservoirs

DEFF Research Database (Denmark)

Yuan, Hao; Shapiro, Alexander

2011-01-01

to more crossflow between layers and lowers the water sweep efficiency. However, this ratio facilitates the fluid diversion caused by the fines migration, leading to a more efficient enhanced oil recovery. The positive contribution from the mobility ratio to the increased oil recovery due to fines...... give rise to reduction of the permeability in water swept zones, which subsequently leads to the diversion of water flow from the initially more permeable layers to the less permeable ones. As a result, the displacement is more even, the water cut at the producer is decreased, and the oil recovery...... is increased. On the other hand, more energy for the pressure drop is required to maintain a constant flow rate. These effects are studied within a new upscaling model developed previously (Zhang et al., 2011). In a communicating layer cake reservoir, higher end-point mobility ratio (water to oil) leads...

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

Science.gov (United States)

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.

Securing Wireless Communications of the Internet of Things from the Physical Layer, An Overview

Science.gov (United States)

Zhang, Junqing; Duong, Trung; Woods, Roger; Marshall, Alan

2017-08-01

The security of the Internet of Things (IoT) is receiving considerable interest as the low power constraints and complexity features of many IoT devices are limiting the use of conventional cryptographic techniques. This article provides an overview of recent research efforts on alternative approaches for securing IoT wireless communications at the physical layer, specifically the key topics of key generation and physical layer encryption. These schemes can be implemented and are lightweight, and thus offer practical solutions for providing effective IoT wireless security. Future research to make IoT-based physical layer security more robust and pervasive is also covered.

Religion, Belief and Medial Layering of Communication. Perspectives from Studies in Visual Culture and Artistic Productions

Directory of Open Access Journals (Sweden)

Sigrid Schade

2015-11-01

Full Text Available The paper analyses the relationship between religious practices, belief and the media based on the medial layering of communication. The arguments are situated within the fields of studies in visual culture and cultural studies, reflecting on the role of art as a specific medium in the Western religious tradition. Vera Frenkel’s video This Is Your Messiah Speaking (1990 is reviewed as a critical inquiry into religious practices and the media structures of communication.

Data communications

International Nuclear Information System (INIS)

Ann, Byeong Ho; Baek, Jeong Hun

1998-01-01

The contents of this book are notion of data communications : summary on data communication, data transmission, data communications system, data transmission technology, data conversion, data link control and control over error of data transmission and exchange of data communications network in the first part, computer communications network architecture : data communications architecture, OSI model, lower layer of OSI model, upper layer of OSI model and distributed surroundings in the second part, data information networking : LAN, FDDI, 100 Base T, DQDB and Frame Relay in the third part, Public Network : PSDN, N-ISDN, B-ISDN in the fourth part, internet and PC communication : emulator program, Binary file, BBS, E-mail service and user on-line service in the last part.

Multi-Layer 5G Mobile Phone Antenna for Multi-User MIMO Communications

DEFF Research Database (Denmark)

Ojaroudiparchin, Naser; Shen, Ming; Pedersen, Gert F.

2015-01-01

for 5G wireless communications. Two identical linear sub arrays can be simultaneously used at different sides of the mobile-phone printed circuit board (PCB) for operation in diversity or multiple-input multiple-output (MIMO) modes. Each sub array contains eight elements of very compact off......-center dipole antennas with dimensions of 5.4×0.67 mm2. The feature of compact design with good beam-steering function makes them well-suited to integrate into the mobile-phone mock-up. The fundamental properties of the proposed antenna have been investigated. Simulations show that the proposed 5G antenna......In this study, a new design of multi-layer phased array antenna for millimeter-wave (mm-Wave) fifth generation (5G) mobile terminals is proposed. The proposed linear phased array antenna is designed on four layers of the Rogers RT5880 substrates to operate at 28 GHz which is under consideration...

An Overview of Physical Layer Security in Wireless Communication Systems With CSIT Uncertainty

KAUST Repository

Hyadi, Amal; Rezki, Zouheir; Alouini, Mohamed-Slim

2016-01-01

The concept of physical layer security builds on the pivotal idea of turning the channel's imperfections, such as noise and fading, into a source of security. This is established through appropriately designed coding techniques and signal processing strategies. In this vein, it has been shown that fading channels can enhance the transmission of confidential information and that a secure communication can be achieved even when the channel to the eavesdropper is better than the main channel. However, to fully benefit from what fading has to offer, the knowledge of the channel state information at the transmitter (CSIT) is of primordial importance. In practical wireless communication systems, CSIT is usually obtained, prior to data transmission, through CSI feedback sent by the receivers. The channel links over which this feedback information is sent can be either noisy, rate-limited, or delayed, leading to CSIT uncertainty. In this paper, we present a comprehensive review of recent and ongoing research works on physical layer security with CSIT uncertainty. We focus on both information theoretic and signal processing approaches to the topic when the uncertainty concerns the channel to the wiretapper or the channel to the legitimate receiver. Moreover, we present a classification of the research works based on the considered channel uncertainty. Mainly, we distinguish between the cases when the uncertainty comes from an estimation error of the CSIT, from a CSI feedback link with limited capacity, or from an outdated CSI.

An Overview of Physical Layer Security in Wireless Communication Systems With CSIT Uncertainty

KAUST Repository

Hyadi, Amal

2016-09-21

The concept of physical layer security builds on the pivotal idea of turning the channel\\'s imperfections, such as noise and fading, into a source of security. This is established through appropriately designed coding techniques and signal processing strategies. In this vein, it has been shown that fading channels can enhance the transmission of confidential information and that a secure communication can be achieved even when the channel to the eavesdropper is better than the main channel. However, to fully benefit from what fading has to offer, the knowledge of the channel state information at the transmitter (CSIT) is of primordial importance. In practical wireless communication systems, CSIT is usually obtained, prior to data transmission, through CSI feedback sent by the receivers. The channel links over which this feedback information is sent can be either noisy, rate-limited, or delayed, leading to CSIT uncertainty. In this paper, we present a comprehensive review of recent and ongoing research works on physical layer security with CSIT uncertainty. We focus on both information theoretic and signal processing approaches to the topic when the uncertainty concerns the channel to the wiretapper or the channel to the legitimate receiver. Moreover, we present a classification of the research works based on the considered channel uncertainty. Mainly, we distinguish between the cases when the uncertainty comes from an estimation error of the CSIT, from a CSI feedback link with limited capacity, or from an outdated CSI.

Redundancy scheme for multi-layered accelerator control system

International Nuclear Information System (INIS)

Chauhan, Amit; Fatnani, Pravin

2009-01-01

The control system for SRS Indus-2 has three-layered architecture. There are VMEbus based stations at the lower two layers that are controlled by their respective CPU board. The 'Profibus' fieldbus standard is used for communication between these VME stations distributed in the field. There is a Profibus controller board at each station to implement the communication protocol. The mode of communication is master-slave (command-response) type. This paper proposes a scheme to implement redundancy at the lower two layers namely Layer-2 (Supervisory Layer / Profibus-master) and Layer-3 (Equipment Unit Interface Layer / Profibus-slave). The redundancy is for both the CPU and the communication board. The scheme uses two CPU boards and two Profi controller boards at each L-3 station. This helps in decreasing any downtime resulting either from CPU faults or communication board faults that are placed in the field area. Redundancy of Profi boards provides two active communication channels between the stations that can be used in different ways thereby increasing the availability on a communication link. Redundancy of CPU boards provides certain level of auto fault-recovery as one CPU remains active and the other CPU remains in standby mode, which takes over the control of VMEbus in case of any fault in the main CPU. (author)

Experience on the FMS Communication module Development for an Application to Safety- Critical Communication Network

Energy Technology Data Exchange (ETDEWEB)

Son, Kwang Seop; Lee, Jang Soo; Kim, Jung Heon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-05-15

The field bus has been developed for a network system which supports the real-time communication of various controls and automation equipment. It is known for Profibus in the field of a production automation environment. The Profibus standard uses open communication based on the ISO/OSI model. The Probibus standard uses layer 1, layer 2, layer 7. Layer 7 of Probibus FMS(Fieldbus Message Specification) provides a information and the user of a station. The high-level communication of the safety-grade PLC (POSAFE-Q) developed through the KNICS(Korea Nuclear I and C System) project is the FMS This paper describes the design, the configuration, and the test method of the FMS communication module.

Experience on the FMS Communication module Development for an Application to Safety- Critical Communication Network

International Nuclear Information System (INIS)

Son, Kwang Seop; Lee, Jang Soo; Kim, Jung Heon

2009-01-01

The field bus has been developed for a network system which supports the real-time communication of various controls and automation equipment. It is known for Profibus in the field of a production automation environment. The Profibus standard uses open communication based on the ISO/OSI model. The Probibus standard uses layer 1, layer 2, layer 7. Layer 7 of Probibus FMS(Fieldbus Message Specification) provides a information and the user of a station. The high-level communication of the safety-grade PLC (POSAFE-Q) developed through the KNICS(Korea Nuclear I and C System) project is the FMS This paper describes the design, the configuration, and the test method of the FMS communication module

Electromagnetic Modeling of the Propagation Characteristics of Satellite Communications Through Composite Precipitation Layers, Part1: Mathematical Formulation

Directory of Open Access Journals (Sweden)

H.M. Al-Rizzo

2000-12-01

Full Text Available A systematic and general formulation of a Propagation Simulation Program (PSP is developed for the coherent field of microwave and millimeter wave carrier signals traversing intermediate layered precipitation media, taking into account the random behavior of particle size, orientation, shape and concentration distributions.  Based on a rigorous solution of the volumetric multiple-scattering integral equations, the formalism offers the capability of treating the potential transmission impairments on satellite-earth links and radar remote sensing generated by composite atmospheric layers of precipitation in conjunction with the finite polarization isolation of dual-polarized transmitting and receiving antennas. A multi-layered formulation is employed which encompasses an ensemble of discrete particles comprising an arbitrary mixture of ice crystals, melting snow and raindrops that may exist simultaneously along satellite-earth communication paths.

Advanced Measurements of the Aggregation Capability of the MPT Network Layer Multipath Communication Library

Directory of Open Access Journals (Sweden)

Gábor Lencse

2015-05-01

Full Text Available The MPT network layer multipath communicationlibrary is a novel solution for several problems including IPv6transition, reliable data transmission using TCP, real-time transmissionusing UDP and also wireless network layer routingproblems. MPT can provide an IPv4 or an IPv6 tunnel overone or more IPv4 or IPv6 communication channels. MPT canalso aggregate the capacity of multiple physical channels. In thispaper, the channel aggregation capability of the MPT libraryis measured up to twelve 100Mbps speed channels. Differentscenarios are used: both IPv4 and IPv6 are used as the underlyingand also as the encapsulated protocols and also both UDP andTCP are used as transport protocols. In addition, measurementsare taken with both 32-bit and 64-bit version of the MPT library.In all cases, the number of the physical channels is increased from1 to 12 and the aggregated throughput is measured.

Regulation of inflorescence architecture by intertissue layer ligand-receptor communication between endodermis and phloem.

Science.gov (United States)

Uchida, Naoyuki; Lee, Jin Suk; Horst, Robin J; Lai, Hung-Hsueh; Kajita, Ryoko; Kakimoto, Tatsuo; Tasaka, Masao; Torii, Keiko U

2012-04-17

Multicellular organisms achieve final body shape and size by coordinating cell proliferation, expansion, and differentiation. Loss of function in the Arabidopsis ERECTA (ER) receptor-kinase gene confers characteristic compact inflorescence architecture, but its underlying signaling pathways remain unknown. Here we report that the expression of ER in the phloem is sufficient to rescue compact er inflorescences. We further identified two Epidermal Patterning Factor-like (EPFL) secreted peptide genes, EPFL4 and EPFL6/CHALLAH (CHAL), as redundant, upstream components of ER-mediated inflorescence growth. The expression of EPFL4 or EPFL6 in the endodermis, a layer adjacent to phloem, is sufficient to rescue the er-like inflorescence of epfl4 epfl6 plants. EPFL4 and EPFL6 physically associate with ER in planta. Finally, transcriptome analysis of er and epfl4 epfl6 revealed a potential downstream component as well as a role for plant hormones in EPFL4/6- and ER-mediated inflorescence growth. Our results suggest that intercell layer communication between the endodermis and phloem mediated by peptide ligands and a receptor kinase coordinates proper inflorescence architecture in Arabidopsis.

A Study of Application Layer Paradigm for Lower Layer Energy Saving Potentials in Cloud-Edge Social User Wireless Image Sharing

Directory of Open Access Journals (Sweden)

Wei Wang

2015-08-01

Full Text Available Energy saving becomes critical in modern cloud wireless multimedia and mobile communication systems. In this paper we propose to study a new paradigm named application layer Position-Value diversity for wireless image sharing for cloud-edge communications, which has significant energy saving potentials for modern wireless networking systems. In this new paradigm, saving energy is achieved by looking into application layer imaging traffic, in stead of MAC-PHY protocols at lower layers, and partitioning it into important positions and unimportant values. This paradigm could be integrated to existing wavelet-based tree compression, and truncation of image bit streams could be performed with regards to wireless communication energy budget estimation. Simulation results demonstrated that there are significant potentials of communication energy efficiency gain and Quality of Experience (QoE enhancement in wireless image communication systems.

Optimized Signaling Method for High-Speed Transmission Channels with Higher Order Transfer Function

Science.gov (United States)

Ševčík, Břetislav; Brančík, Lubomír; Kubíček, Michal

2017-08-01

In this paper, the selected results from testing of optimized CMOS friendly signaling method for high-speed communications over cables and printed circuit boards (PCBs) are presented and discussed. The proposed signaling scheme uses modified concept of pulse width modulated (PWM) signal which enables to better equalize significant channel losses during data high-speed transmission. Thus, the very effective signaling method to overcome losses in transmission channels with higher order transfer function, typical for long cables and multilayer PCBs, is clearly analyzed in the time and frequency domain. Experimental results of the measurements include the performance comparison of conventional PWM scheme and clearly show the great potential of the modified signaling method for use in low power CMOS friendly equalization circuits, commonly considered in modern communication standards as PCI-Express, SATA or in Multi-gigabit SerDes interconnects.

Composite three-layer closure of oral antral communication with 10 months follow-up-a case study.

Science.gov (United States)

Weinstock, Robert J; Nikoyan, Levon; Dym, Harry

2014-02-01

We propose a 3-layer composite closure technique for an oral antral communication (OAC) while avoiding secondary donor site morbidity. A patient had developed a 1-cm OAC after extraction of right maxillary first molar. The patient subsequently developed acute maxillary sinusitis. The patient was taken to the operating room, and a Caldwell-Luc procedure was performed. The bony window from the Caldwell-Luc was "press fit" over the bony OAC defect. Soft tissue closure was then achieved with a buccal fat pad flap and a buccal mucosal advancement flap. The patient was examined on postoperative day 5 and 1, 2, 3, 6, and 10 months postoperatively. The acute sinusitis had resolved. The soft tissue closure was successful. The bone graft remained intact, prevented sinus pneumatization, and restored continuity to the floor of the maxillary sinus. The presented technique for 3-layer closure of OACs allows for the stability of a double-layer closure of OAC with the added benefit of bone grafting from single operative site, achieving stable oral antral closure, bone grafting, and the avoidance of secondary donor site morbidity. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Method of performing a layer operation in a communications network

NARCIS (Netherlands)

Bosch, H.G.P.; Mullender, Sape J.; Narlikar, G.J.

2006-01-01

In an embodiment of the present invention, a scheduling operation is performed at a lower layer based on upper layer information. In another embodiment of the present invention, an action is performed at an upper layer based on received lower layer information. Also, a scheduling operation may be

Underwater Optical Wireless Communications, Networking, and Localization: A Survey

KAUST Repository

Saeed, Nasir; Celik, Abdulkadir; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2018-01-01

Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Compared to its bandwidth limited acoustic and RF counterparts, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. However, severe aquatic channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great challenges for UOWCs and significantly reduce the attainable communication ranges, which necessitates efficient networking and localization solutions. Therefore, we provide a comprehensive survey on the challenges, advances, and prospects of underwater optical wireless networks (UOWNs) from a layer by layer perspective which includes: 1) Potential network architectures; 2) Physical layer issues including propagation characteristics, channel modeling, and modulation techniques 3) Data link layer problems covering link configurations, link budgets, performance metrics, and multiple access schemes; 4) Network layer topics containing relaying techniques and potential routing algorithms; 5) Transport layer subjects such as connectivity, reliability, flow and congestion control; 6) Application layer goals and state-of-the-art UOWN applications, and 7) Localization and its impacts on UOWN layers. Finally, we outline the open research challenges and point out the future directions for underwater optical wireless communications, networking, and localization research.

Underwater Optical Wireless Communications, Networking, and Localization: A Survey

KAUST Repository

Saeed, Nasir

2018-02-28

Underwater wireless communications can be carried out through acoustic, radio frequency (RF), and optical waves. Compared to its bandwidth limited acoustic and RF counterparts, underwater optical wireless communications (UOWCs) can support higher data rates at low latency levels. However, severe aquatic channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great challenges for UOWCs and significantly reduce the attainable communication ranges, which necessitates efficient networking and localization solutions. Therefore, we provide a comprehensive survey on the challenges, advances, and prospects of underwater optical wireless networks (UOWNs) from a layer by layer perspective which includes: 1) Potential network architectures; 2) Physical layer issues including propagation characteristics, channel modeling, and modulation techniques 3) Data link layer problems covering link configurations, link budgets, performance metrics, and multiple access schemes; 4) Network layer topics containing relaying techniques and potential routing algorithms; 5) Transport layer subjects such as connectivity, reliability, flow and congestion control; 6) Application layer goals and state-of-the-art UOWN applications, and 7) Localization and its impacts on UOWN layers. Finally, we outline the open research challenges and point out the future directions for underwater optical wireless communications, networking, and localization research.

Layers And Processes In The Model Of Technological Postal System

Directory of Open Access Journals (Sweden)

Madleňáková Lucia

2015-12-01

Full Text Available The paper include important aspects of layer model of postal technological system such as makes the possibility to define rules for regulating, technical and technological requirements and interfaces to communicate with other postal systems. The current postal reform is mainly attributable to release of network access and ensuring full interoperability between technological systems. Not only to ensure the development and protection of competition but also in respect to the conservation of requirements to provide the universal service, which is the performance of public interest. There is a space here to examine the postal system, not only from a procedural point of view, but to be viewed as an open communication system. It is possible to find there the commonalities with other communication sector branches and to handle the technological postal system in more layers; similarly as the electronic communication systems are handled. Model of layer postal system, based not only on the processes but on layers functionality, will enable to identify communication protocols and interfaces determining interoperability. It also opens the question of appropriate regulation model.

Wireless Physical Layer Security: On the Performance Limit of Secret-Key Agreement

KAUST Repository

Zorgui, Marwen

2015-01-01

Physical layer security (PLS) is a new paradigm aiming at securing communications between legitimate parties at the physical layer. Conventionally, achieving confidentiality in communication networks relies on cryptographic techniques such as public

Cross-layer design in optical networks

CERN Document Server

Brandt-Pearce, Maïté; Demeester, Piet; Saradhi, Chava

2013-01-01

Optical networks have become an integral part of the communications infrastructure needed to support society’s demand for high-speed connectivity.  Cross-Layer Design in Optical Networks addresses topics in optical network design and analysis with a focus on physical-layer impairment awareness and network layer service requirements, essential for the implementation and management of robust scalable networks.  The cross-layer treatment includes bottom-up impacts of the physical and lambda layers, such as dispersion, noise, nonlinearity, crosstalk, dense wavelength packing, and wavelength line rates, as well as top-down approaches to handle physical-layer impairments and service requirements.

Real-time data access layer for MDSplus

International Nuclear Information System (INIS)

Manduchi, G.; Luchetta, A.; Taliercio, C.; Fredian, T.; Stillerman, J.

2008-01-01

Recent extensions to MDSplus allow data handling in long discharges and provide a real-time data access and communication layer. The real-time data access layer is an additional component of MDSplus: it is possible to use the traditional MDSplus API during normal operation, and to select a subset of data items to be used in real time. Real-time notification is provided by a communication layer using a publish-subscribe pattern. The notification covers processes sharing the same data items even running on different machines, thus allowing the implementation of distributed control systems. The real-time data access layer has been developed for Windows, Linux, and VxWorks; it is currently being ported to Linux RTAI. In order to quantify the fingerprint of the presented system, the performance of the real-time access layer approach is compared with that of an ad hoc, manually optimized program in a sample real-time application

Asymmetrically interacting spreading dynamics on complex layered networks.

Science.gov (United States)

Wang, Wei; Tang, Ming; Yang, Hui; Younghae Do; Lai, Ying-Cheng; Lee, GyuWon

2014-05-29

The spread of disease through a physical-contact network and the spread of information about the disease on a communication network are two intimately related dynamical processes. We investigate the asymmetrical interplay between the two types of spreading dynamics, each occurring on its own layer, by focusing on the two fundamental quantities underlying any spreading process: epidemic threshold and the final infection ratio. We find that an epidemic outbreak on the contact layer can induce an outbreak on the communication layer, and information spreading can effectively raise the epidemic threshold. When structural correlation exists between the two layers, the information threshold remains unchanged but the epidemic threshold can be enhanced, making the contact layer more resilient to epidemic outbreak. We develop a physical theory to understand the intricate interplay between the two types of spreading dynamics.

Optimization and Control of Communication Networks

OpenAIRE

Chiang, Mung; Low, Steven

2005-01-01

Recently, there has been a surge in research activities that utilize the power of recent developments in nonlinear optimization to tackle a wide scope of work in the analysis and design of communication systems, touching every layer of the layered network architecture, and resulting in both intellectual and practical impacts significantly beyond the earlier frameworks. These research activities are driven by both new demands in the areas of communications and networking, and n...

High-rate wireless data communications: An underwater acoustic communications framework at the physical layer

Directory of Open Access Journals (Sweden)

Bessios Anthony G.

1996-01-01

Full Text Available A variety of signal processing functions are performed by Underwater Acoustic Systems. These include: 1 detection to determine presence or absence of information signals in the presence of noise, or an attempt to describe which of a predetermined finite set of possible messages { m i , i , ... , M } the signal represents; 2 estimation of some parameter θ ˆ associated with the received signal (i.e. range, depth, bearing angle, etc.; 3 classification and source identification; 4 dynamics tracking; 5 navigation (collision avoidance and terminal guidance; 6 countermeasures; and 7 communications. The focus of this paper is acoustic communications. There is a global current need to develop reliable wireless digital communications for the underwater environment, with sufficient performance and efficiency to substitute for costly wired systems. One possible goal is a wireless system implementation that insures underwater terminal mobility. There is also a vital need to improve the performance of the existing systems in terms of data-rate, noise immunity, operational range, and power consumption, since, in practice, portable high-speed, long range, compact, low-power systems are desired. We concede the difficulties associated with acoustic systems and concentrate on the development of robust data transmission methods anticipating the eventual need for real time or near real time video transmission. An overview of the various detection techniques and the general statistical digital communication problem is given based on a statistical decision theory framework. The theoretical formulation of the underwater acoustic data communications problem includes modeling of the stochastic channel to incorporate a variety of impairments and environmental uncertainties, and proposal of new compensation strategies for an efficient and robust receiver design.

Communication Systems and Study Method for Active Distribution Power systems

DEFF Research Database (Denmark)

Wei, Mu; Chen, Zhe

Due to the involvement and evolvement of communication technologies in contemporary power systems, the applications of modern communication technologies in distribution power system are becoming increasingly important. In this paper, the International Organization for Standardization (ISO......) reference seven-layer model of communication systems, and the main communication technologies and protocols on each corresponding layer are introduced. Some newly developed communication techniques, like Ethernet, are discussed with reference to the possible applications in distributed power system....... The suitability of the communication technology to the distribution power system with active renewable energy based generation units is discussed. Subsequently the typical possible communication systems are studied by simulation. In this paper, a novel method of integrating communication system impact into power...

Power line communications theory and applications for narrowband and broadband communications over power lines

CERN Document Server

Ferreira, Hendrik C; Newbury, John; Swart, Theo G

2010-01-01

Power Line Communications (PLC) is a promising emerging technology, which has attracted much attention due to the wide availability of power distribution lines. This book provides a thorough introduction to the use of power lines for communication purposes, ranging from channel characterization, communications on the physical layer and electromagnetic interference, through to protocols, networks, standards and up to systems and implementations. With contributions from many of the most prominent international PLC experts from academia and industry, Power Line Communications brings togeth

A Perspective of Layerless Communications

DEFF Research Database (Denmark)

Prasad, Ramjee

2008-01-01

Recent advances in wireless and mobile communications provide ample opportunities for introducing new services. Supporting multimedia applications and services over wireless networks is challenging due to contraints and heterogeneities such as limited battery power, limited bandwidth, random time...... cross-layer design from the perspective of simplifying the cross-layer procedures towards layers merging. Studies and observations are based on the use of cognitive radio technology as the means for optimization of the cross-layer design process....

Cooperative communications hardware, channel and PHY

CERN Document Server

Dohler, Mischa

2010-01-01

Facilitating Cooperation for Wireless Systems Cooperative Communications: Hardware, Channel & PHY focuses on issues pertaining to the PHY layer of wireless communication networks, offering a rigorous taxonomy of this dispersed field, along with a range of application scenarios for cooperative and distributed schemes, demonstrating how these techniques can be employed. The authors discuss hardware, complexity and power consumption issues, which are vital for understanding what can be realized at the PHY layer, showing how wireless channel models differ from more traditional

Synchronous message-based communication for distributed heterogeneous systems

International Nuclear Information System (INIS)

Wilkinson, N.; Dohan, D.

1992-01-01

The use of a synchronous, message-based real-time operating system (Unison) as the basis of transparent interprocess and inter-processor communication over VME-bus is described. The implementation of a synchronous, message-based protocol for network communication between heterogeneous systems is discussed. In particular, the design and implementation of a message-based session layer over a virtual circuit transport layer protocol using UDP/IP is described. Inter-process communication is achieved via a message-based semantic which is portable by virtue of its ease of implementation in other operating system environments. Protocol performance for network communication among heterogeneous architecture is presented, including VMS, Unix, Mach and Unison. (author)

Feature-Driven Domain Analysis of Session Layer Protocols of Internet of Things

NARCIS (Netherlands)

Köksal, Omer; Tekinerdogan, B.

2017-01-01

The Internet of Things (IoT) architecture is defined as a layered structure in which each layer represents a coherent set of services. For supporting the communication among the different IoT entities many different communication protocols are now available in practice. For practitioners, it is

Communicating Cooperative Robots with Bluetooth

DEFF Research Database (Denmark)

Schiøler, Henrik; Son, L.T.; Madsen, Ole Brun

2001-01-01

A generic architecture for system of cooperating communicating mobile robots is presented. An overall structure is defined from a modularity viewpoint, where a number of generic modules are identified; low level communication interface, network layer services such as initial and adaptive network...... structuring, routing and capacity management, overall behaviour which includes commitment to overall strategies as well as local behaviour like trajectory planning and navigation. Focus is kept on communication aspects and an example application of establishing a reliable wireless real-time communication...

Propagation of microwave radiation through an inhomogeneous plasma layer in a magnetic field

Science.gov (United States)

Balakirev, B. A.; Bityurin, V. A.; Bocharov, A. N.; Brovkin, V. G.; Vedenin, P. V.; Mashek, I. Ch; Pashchina, A. S.; Pervov, A. Yu; Petrovskiy, V. P.; Ryazanskiy, N. M.; Shkatov, O. Yu

2018-01-01

The problem of reliable microwave communication through a plasma sheath has its origin from the beginning of space flights. During reentry of spacecraft, the plasma layer can interrupt the communication. At sufficiently high plasma density, the plasma layer either reflects or attenuates radio wave communications to and from the vehicle. In this work, we present a simple analytical one-dimensional algorithm to study the propagation of electromagnetic (EM) waves through a nonuniform plasma layer in a static nonuniform magnetic field. The experimental study of the EM wave transmission and reflection through plasma layer was carried out on the (i) microwave set and (ii) on the unit using a high-voltage pulsed discharge.

Two-Layer Hierarchy Optimization Model for Communication Protocol in Railway Wireless Monitoring Networks

Directory of Open Access Journals (Sweden)

Xiaoping Ma

2018-01-01

Full Text Available The wireless monitoring system is always destroyed by the insufficient energy of the sensors in railway. Hence, how to optimize the communication protocol and extend the system lifetime is crucial to ensure the stability of system. However, the existing studies focused primarily on cluster-based or multihop protocols individually, which are ineffective in coping with the complex communication scenarios in the railway wireless monitoring system (RWMS. This study proposes a hybrid protocol which combines the cluster-based and multihop protocols (CMCP to minimize and balance the energy consumption in different sections of the RWMS. In the first hierarchy, the total energy consumption is minimized by optimizing the cluster quantities in the cluster-based protocol and the number of hops and the corresponding hop distances in the multihop protocol. In the second hierarchy, the energy consumption is balanced through rotating the cluster head (CH in the subnetworks and further optimizing the hops and the corresponding hop distances in the backbone network. On this basis, the system lifetime is maximized with the minimum and balance energy consumption among the sensors. Furthermore, the hybrid particle swarm optimization and genetic algorithm (PSO-GA are adopted to optimize the energy consumption from the two-layer hierarchy. Finally, the effectiveness of the proposed CMCP is verified in the simulation. The performances of the proposed CMCP in system lifetime, residual energy, and the corresponding variance are all superior to the LEACH protocol widely applied in the previous research. The effective protocol proposed in this study can facilitate the application of the wireless monitoring network in the railway system and enhance safety operation of the railway.

Mixing chaos modulations for secure communications in OFDM systems

Science.gov (United States)

Seneviratne, Chatura; Leung, Henry

2017-12-01

In this paper, we consider a novel chaotic OFDM communication scheme is to improve the physical layer security. By secure communication we refer to physical layer security that provides low probability of detection (LPD)/low probability of intercept (LPI) transmission. A mixture of chaotic modulation schemes is used to generate chaotically modulated symbols for each subcarrier of the OFDM transmitter. At the receiver, different demodulators are combined together for the different modulation schemes for enhanced security. Time domain, frequency domain and statistical randomness tests show that transmit signals are indistinguishable from background noise. BER performance comparison shows that the physical layer security of the proposed scheme comes with a slight performance degradation compared to conventional OFDM communication systems.

Research of the self-healing technologies in the optical communication network of distribution automation

Science.gov (United States)

Wang, Hao; Zhong, Guoxin

2018-03-01

Optical communication network is the mainstream technique of the communication networks for distribution automation, and self-healing technologies can improve the in reliability of the optical communication networks significantly. This paper discussed the technical characteristics and application scenarios of several network self-healing technologies in the access layer, the backbone layer and the core layer of the optical communication networks for distribution automation. On the base of the contrastive analysis, this paper gives an application suggestion of these self-healing technologies.

Layer transfer by controlled spalling

International Nuclear Information System (INIS)

Bedell, Stephen W; Fogel, Keith; Lauro, Paul; Shahrjerdi, Davood; Ott, John A; Sadana, Devendra

2013-01-01

In this communication, we present what may be the simplest method yet devised for removing surface layers from brittle substrates. The process is called controlled spalling technology (CST) and works by depositing a tensile stressor layer on the surface of a substrate, introducing a crack near the edge of the substrate, and mechanically guiding the crack as a single fracture front across the surface. The entire process is performed at room-temperature using only common laboratory equipment. We present here, for the first time, the specific process conditions required for controlled spalling of Ge 〈0 0 1〉 substrates using Ni as the stressor layer. We also illustrate the versatility of CST by removing completed CMOS circuits from a Si wafer and demonstrate functionality of the flexible circuits. Raman spectroscopy of spalled circuits with the Ni stressor intact indicates a residual compressive Si strain of 0.0029, in good agreement with the calculated value of 0.0022. Therefore, CST also permits new opportunities for strain engineering of nanoscale devices. (fast track communication)

A two-layer architecture for force-reflecting bilateral teleoperation with time delays

NARCIS (Netherlands)

Heck, D.J.F.; Saccon, A.; Nijmeijer, H.

2015-01-01

We propose a two-layer control architecture for bilateral teleoperation with communication delays. The controller is structured with an (outer) performance layer and an (inner) passivity layer. In the performance layer, any traditional controller for bilateral teleoperation can be implemented. In

Layered AMI Architecture for Various Grid Topologies and Communication Technologies

Directory of Open Access Journals (Sweden)

I. Petruševski

2016-06-01

Full Text Available Advanced metering infrastructure (AMI system, proposed in this paper, is capable of fulfilling all smart metering functionalities in real-time. The novel Local Metering Concentrator (LMC layer is introduced as the set of independent embedded system components, allowing distributed architecture implementation. Two main data flows can be defined as command request processing and meter data acquisition. A command request, initiated by some of the top layer applications, is processed and forwarded through the system to the LMC layer, where the request is executed and the status is sent as a reply. The data and event acquisition is performed as an automatic function of the LMC layer. The collected data is forwarded to the system as soon as it is downloaded from the meters. The results of more than one-year exploitation of the installed pilot system are presented, emphasizing the real-time load profile data acquisition, allowing the distribution system operators (DSO and the end consumer to be actively involved in energy saving. The introduced architecture enables load profiling, energy diagnostic and easy integration with any meter data management system.

Quantitative Safety and Security Analysis from a Communication Perspective

DEFF Research Database (Denmark)

Malinowsky, Boris; Schwefel, Hans-Peter; Jung, Oliver

2014-01-01

This paper introduces and exemplifies a trade-off analysis of safety and security properties in distributed systems. The aim is to support analysis for real-time communication and authentication building blocks in a wireless communication scenario. By embedding an authentication scheme into a real...... at handover situations in a IEEE 802.11 wireless setup between mobile nodes and access points. The trade-offs involve application-layer data goodput, probability of completed handovers, and effect on usable protocol slots, to quantify the impact of security from a lower-layer communication perspective...

Opportunities for IP  in Communications Beyond 3G

DEFF Research Database (Denmark)

Nielsen, Thomas Toftegaard; Jacobsen, Rune H.

2005-01-01

Future communication will be based on TCP/IP as common network and transport layers to provide global connectivity to users and applications. IP is used to provide ubiquitous access across different access networks and exploits the benefits of a common connectivity layer while reducing the cost...... of operation and maintenance of the network. This paper discusses the opportunities for IP in the evolution towards a future broadband, all-IP mobile communication network. In particular, we argue for three opportunities for the future: Interworking access technologies over IP, IP layer transparency...

Cooperative Communications for Wireless Information Assurance: Secure Cooperative Communications and Testbed Development

National Research Council Canada - National Science Library

Li, Xiaohua

2007-01-01

..., and have invented a new cooperative OFDM transmission scheme to combat transmission asynchronism. They are helpful to the development of future physical-layer wireless information assurance techniques as well as the cooperative communication techniques...

Radio Transmitters and Tower Locations, Layer includes all towers identified visually and include cellular and other communication towers., Published in 2008, 1:1200 (1in=100ft) scale, Noble County Government.

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Radio Transmitters and Tower Locations dataset current as of 2008. Layer includes all towers identified visually and include cellular and other communication towers..

On the Secrecy Degrees of Freedom with Full-Duplex Communication

DEFF Research Database (Denmark)

Mahmood, Nurul Huda; Mogensen, Preben Elgaard

2017-01-01

of such an application. The potential of full duplex nodes in improving the physical layer security of a communication link is investigated in this contribution. We specifically derive the information theoretic secrecy degrees of freedom measure for a pair of nodes communicating in full duplex mode. Moreover, closed...... and the delay reduction of full duplex communication are somewhat limited in realistic network settings, leading researchers to study other possible applications of full duplex communication which can provide significantly higher gains over half duplex communication. Physical layer security is an example...... form expressions for the instantaneous and ergodic throughput gain of full duplex communication over conventional half duplex is derived. The secrecy degrees of freedom with full duplex is shown to be two as opposed to that of zero in half duplex mode....

Quantitative Safety and Security Analysis from a Communication Perspective

Directory of Open Access Journals (Sweden)

Boris Malinowsky

2015-12-01

Full Text Available This paper introduces and exemplifies a trade-off analysis of safety and security properties in distributed systems. The aim is to support analysis for real-time communication and authentication building blocks in a wireless communication scenario. By embedding an authentication scheme into a real-time communication protocol for safety-critical scenarios, we can rely on the protocol’s individual safety and security properties. The resulting communication protocol satisfies selected safety and security properties for deployment in safety-critical use-case scenarios with security requirements. We look at handover situations in a IEEE 802.11 wireless setup between mobile nodes and access points. The trade-offs involve application-layer data goodput, probability of completed handovers, and effect on usable protocol slots, to quantify the impact of security from a lower-layer communication perspective on the communication protocols. The results are obtained using the network simulator ns-3.

Collaborative communication protocols for wireless sensor networks

NARCIS (Netherlands)

Dulman, S.O.; van Hoesel, L.F.W.; Nieberg, T.; Havinga, Paul J.M.

In this document, the design of communication within a wireless sensor network is discussed. The resource limitations of such a network, especially in terms of energy, require an integrated approach for all (traditional) layers of communication. We present such an integrated, collaborative approach

Hiding in plain sight: communication theory in implementation science.

Science.gov (United States)

Manojlovich, Milisa; Squires, Janet E; Davies, Barbara; Graham, Ian D

2015-04-23

Poor communication among healthcare professionals is a pressing problem, contributing to widespread barriers to patient safety. The word "communication" means to share or make common. In the literature, two communication paradigms dominate: (1) communication as a transactional process responsible for information exchange, and (2) communication as a transformational process responsible for causing change. Implementation science has focused on information exchange attributes while largely ignoring transformational attributes of communication. In this paper, we debate the merits of encompassing both paradigms. We conducted a two-staged literature review searching for the concept of communication in implementation science to understand how communication is conceptualized. Twenty-seven theories, models, or frameworks were identified; only Rogers' Diffusion of Innovations theory provides a definition of communication and includes both communication paradigms. Most models (notable exceptions include Diffusion of Innovations, The Ottawa Model of Research Use, and Normalization Process Theory) describe communication as a transactional process. But thinking of communication solely as information transfer or exchange misrepresents reality. We recommend that implementation science theories (1) propose and test the concept of shared understanding when describing communication, (2) acknowledge that communication is multi-layered, identify at least a few layers, and posit how identified layers might affect the development of shared understanding, (3) acknowledge that communication occurs in a social context, providing a frame of reference for both individuals and groups, (4) acknowledge the unpredictability of communication (and healthcare processes in general), and (5) engage with and draw on work done by communication theorists. Implementation science literature has conceptualized communication as a transactional process (when communication has been mentioned at all), thereby

Direct force-reflecting two-layer approach for passive bilateral teleoperation with time delays

NARCIS (Netherlands)

Heck, D.; Saccon, A.; Beerens, R.; Nijmeijer, H.

2018-01-01

We propose a two-layer control architecture for bilateral teleoperation with communication delays. The controller is structured with an (inner) performance layer and an (outer) passivity layer. In the performance layer, any traditional controller for bilateral teleoperation can be implemented. The

Cross Layer Optimization and Simulation of Smart Grid Home Area Network

Directory of Open Access Journals (Sweden)

Lipi K. Chhaya

2018-01-01

Full Text Available An electrical “Grid” is a network that carries electricity from power plants to customer premises. Smart Grid is an assimilation of electrical and communication infrastructure. Smart Grid is characterized by bidirectional flow of electricity and information. Smart Grid is a complex network with hierarchical architecture. Realization of complete Smart Grid architecture necessitates diverse set of communication standards and protocols. Communication network protocols are engineered and established on the basis of layered approach. Each layer is designed to produce an explicit functionality in association with other layers. Layered approach can be modified with cross layer approach for performance enhancement. Complex and heterogeneous architecture of Smart Grid demands a deviation from primitive approach and reworking of an innovative approach. This paper describes a joint or cross layer optimization of Smart Grid home/building area network based on IEEE 802.11 standard using RIVERBED OPNET network design and simulation tool. The network performance can be improved by selecting various parameters pertaining to different layers. Simulation results are obtained for various parameters such as WLAN throughput, delay, media access delay, and retransmission attempts. The graphical results show that various parameters have divergent effects on network performance. For example, frame aggregation decreases overall delay but the network throughput is also reduced. To prevail over this effect, frame aggregation is used in combination with RTS and fragmentation mechanisms. The results show that this combination notably improves network performance. Higher value of buffer size considerably increases throughput but the delay is also greater and thus the choice of optimum value of buffer size is inevitable for network performance optimization. Parameter optimization significantly enhances the performance of a designed network. This paper is expected to serve

SC-FDMA for mobile communications

CERN Document Server

Abd El-Samie, Fathi E

2013-01-01

SC-FDMA for Mobile Communications examines Single-Carrier Frequency Division Multiple Access (SC-FDMA). Explaining this rapidly evolving system for mobile communications, it describes its advantages and limitations and outlines possible solutions for addressing its current limitations. The book explores the emerging trend of cooperative communication with SC-FDMA and how it can improve the physical layer security. It considers the design of distributed coding schemes and protocols for wireless relay networks where users cooperate to send their data to the destination. Supplying you with the re

Physical layer network coding

DEFF Research Database (Denmark)

Fukui, Hironori; Popovski, Petar; Yomo, Hiroyuki

2014-01-01

Physical layer network coding (PLNC) has been proposed to improve throughput of the two-way relay channel, where two nodes communicate with each other, being assisted by a relay node. Most of the works related to PLNC are focused on a simple three-node model and they do not take into account...

Collaborative Algortihms for Communication in Wireless Sensor Networks

NARCIS (Netherlands)

Nieberg, T.; Dulman, S.O.; Havinga, Paul J.M.; van Hoesel, L.F.W.; Wu Jian, W.J.

In this paper, we present the design of the communication in a wireless sensor network. The resource limitations of a wireless sensor network, especially in terms of energy, require an integrated, and collaborative approach for the different layers of communication. In particular, energy-efficient

Collaborative Algorithms for Communication in Wireless Sensor Networks

NARCIS (Netherlands)

Nieberg, T.; Dulman, S.O.; Havinga, Paul J.M.; van Hoesel, L.F.W.; Wu Jian, W.J.; Basten, Twan; Geilen, Marc; de Groot, Harmke

2003-01-01

In this paper, we present the design of the communication in a wireless sensor network. The resource limitations of a wireless sensor network, especially in terms of energy, require an integrated, and collaborative approach for the different layers of communication. In particular, energy-efficient

Physical Layer Design in Wireless Sensor Networks for Fading Mitigation

Directory of Open Access Journals (Sweden)

Nuo Chen

2013-09-01

Full Text Available This paper presents the theoretical analysis, simulation results and suggests design in digital technology of a physical layer for wireless sensor networks. The proposed design is able to mitigate fading inside communication channel. To mitigate fading the chip interleaving technique is proposed. For the proposed theoretical model of physical layer, a rigorous mathematical analysis is conducted, where all signals are presented and processed in discrete time domain form which is suitable for further direct processing necessary for devices design in digital technology. Three different channels are used to investigate characteristics of the physical layer: additive white Gaussian noise channel (AWGN, AWG noise and flat fading channel and AWG noise and flat fading channel with interleaver and deinterleaver blocks in the receiver and transmitter respectively. Firstly, the mathematical model of communication system representing physical layer is developed based on the discrete time domain signal representation and processing. In the existing theory, these signals and their processing are represented in continuous time form, which is not suitable for direct implementation in digital technology. Secondly, the expressions for the probability of chip, symbol and bit error are derived. Thirdly, the communication system simulators are developed in MATLAB. The simulation results confirmed theoretical findings.

A Laminar Organization for Selective Cortico-Cortical Communication

Directory of Open Access Journals (Sweden)

Rinaldo D. D’Souza

2017-08-01

Full Text Available The neocortex is central to mammalian cognitive ability, playing critical roles in sensory perception, motor skills and executive function. This thin, layered structure comprises distinct, functionally specialized areas that communicate with each other through the axons of pyramidal neurons. For the hundreds of such cortico-cortical pathways to underlie diverse functions, their cellular and synaptic architectures must differ so that they result in distinct computations at the target projection neurons. In what ways do these pathways differ? By originating and terminating in different laminae, and by selectively targeting specific populations of excitatory and inhibitory neurons, these “interareal” pathways can differentially control the timing and strength of synaptic inputs onto individual neurons, resulting in layer-specific computations. Due to the rapid development in transgenic techniques, the mouse has emerged as a powerful mammalian model for understanding the rules by which cortical circuits organize and function. Here we review our understanding of how cortical lamination constrains long-range communication in the mammalian brain, with an emphasis on the mouse visual cortical network. We discuss the laminar architecture underlying interareal communication, the role of neocortical layers in organizing the balance of excitatory and inhibitory actions, and highlight the structure and function of layer 1 in mouse visual cortex.

Multimode Communication Protocols Enabling Reconfigurable Radios

Directory of Open Access Journals (Sweden)

Berlemann Lars

2005-01-01

Full Text Available This paper focuses on the realization and application of a generic protocol stack for reconfigurable wireless communication systems. This focus extends the field of software-defined radios which usually concentrates on the physical layer. The generic protocol stack comprises common protocol functionality and behavior which are extended through specific parts of the targeted radio access technology. This paper considers parameterizable modules of basic protocol functions residing in the data link layer of the ISO/OSI model. System-specific functionality of the protocol software is realized through adequate parameterization and composition of the generic modules. The generic protocol stack allows an efficient realization of reconfigurable protocol software and enables a completely reconfigurable wireless communication system. It is a first step from side-by-side realized, preinstalled modes in a terminal towards a dynamic reconfigurable anymode terminal. The presented modules of the generic protocol stack can also be regarded as a toolbox for the accelerated and cost-efficient development of future communication protocols.

A primer on physical-layer network coding

CERN Document Server

Liew, Soung Chang; Zhang, Shengli

2015-01-01

The concept of physical-layer network coding (PNC) was proposed in 2006 for application in wireless networks. Since then it has developed into a subfield of communications and networking with a wide following. This book is a primer on PNC. It is the outcome of a set of lecture notes for a course for beginning graduate students at The Chinese University of Hong Kong. The target audience is expected to have some prior background knowledge in communication theory and wireless communications, but not working knowledge at the research level. Indeed, a goal of this book/course is to allow the reader

Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems

Science.gov (United States)

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

Three-Year-Olds Hide Their Communicative Intentions in Appropriate Contexts

Science.gov (United States)

Grosse, Gerlind; Scott-Phillips, Thomas C.; Tomasello, Michael

2013-01-01

Human cooperative communication involves both an informative intention that the recipient understands the content of the signal and also a (Gricean) communicative intention that the recipient recognizes that the speaker has an informative intention. The degree to which children understand this 2-layered nature of communication is the subject of…

Solar effects on communications

International Nuclear Information System (INIS)

Cleveland, F.; Malcolm, W.; Nordell, D.E.; Zirker, J.

1991-01-01

When people involved in the power industry think of Solar Magnetic Disturbances (SMD), they normally consider the potential for disrupting power transmission which results form solar-induced disturbances to the earth's magnetic field known as geomagnetic storms. However, in addition to the disruption of power transmission, solar phenomena can interfere with utility communication systems. Utilities use many different types of communication media, some of which can be affected by various solar phenomena. These include wire-based facilities (metallic cables and power line carrier), radio systems (HF, VHF, UHF mobile radio, microwave networks, and satellite transmissions), and fiber optic systems. This paper reports that the solar flares and other solar phenomena can affect these media through different mechanisms: Radio communications can be disturbed by flare-induced changes in the ionispheric layer of the atmosphere; Cable communications can be disrupted by the flare-induced changes in the magnetosphere which surrounds the earth. These changes, in turn, induce currents in the power equipment that energizes long communications cables; Satellite communications can be disrupted by the flare-induced perturbations of satellite orbits and equipment

Protocol for Communication Networking for Formation Flying

Science.gov (United States)

Jennings, Esther; Okino, Clayton; Gao, Jay; Clare, Loren

2009-01-01

An application-layer protocol and a network architecture have been proposed for data communications among multiple autonomous spacecraft that are required to fly in a precise formation in order to perform scientific observations. The protocol could also be applied to other autonomous vehicles operating in formation, including robotic aircraft, robotic land vehicles, and robotic underwater vehicles. A group of spacecraft or other vehicles to which the protocol applies could be characterized as a precision-formation- flying (PFF) network, and each vehicle could be characterized as a node in the PFF network. In order to support precise formation flying, it would be necessary to establish a corresponding communication network, through which the vehicles could exchange position and orientation data and formation-control commands. The communication network must enable communication during early phases of a mission, when little positional knowledge is available. Particularly during early mission phases, the distances among vehicles may be so large that communication could be achieved only by relaying across multiple links. The large distances and need for omnidirectional coverage would limit communication links to operation at low bandwidth during these mission phases. Once the vehicles were in formation and distances were shorter, the communication network would be required to provide high-bandwidth, low-jitter service to support tight formation-control loops. The proposed protocol and architecture, intended to satisfy the aforementioned and other requirements, are based on a standard layered-reference-model concept. The proposed application protocol would be used in conjunction with conventional network, data-link, and physical-layer protocols. The proposed protocol includes the ubiquitous Institute of Electrical and Electronics Engineers (IEEE) 802.11 medium access control (MAC) protocol to be used in the datalink layer. In addition to its widespread and proven use in

Cellular communications a comprehensive and practical guide

CERN Document Server

Tripathi, Nishith

2014-01-01

Even as newer cellular technologies and standards emerge, many of the fundamental principles and the components of the cellular network remain the same. Presenting a simple yet comprehensive view of cellular communications technologies, Cellular Communications provides an end-to-end perspective of cellular operations, ranging from physical layer details to call set-up and from the radio network to the core network. This self-contained source forpractitioners and students represents a comprehensive survey of the fundamentals of cellular communications and the landscape of commercially deployed

Physical-Layer Security with Full-Duplex Transceivers and Multiuser Receiver at Eve

DEFF Research Database (Denmark)

Mahmood, Nurul Huda; Shafique Ansari, Imran; Popovski, Petar

2017-01-01

, leading researchers to study other possible applications that can accord higher gains. The potential of full-duplex communication in improving the physical-layer security of a communication link is investigated in this contribution. We specifically present a thorough analysis of the achievable ergodic...

Cross-layer optimization of wireless multi-hop networks

OpenAIRE

Soldati, Pablo

2007-01-01

The interest in wireless communications has grown constantly for the past decades, leading to an enormous number of applications and services embraced by billions of users. In order to meet the increasing demand for mobile Internet access, several high data-rate radio networking technologies have been proposed to offer wide area high-speed wireless communications, eventually replacing fixed (wired) networks for many applications. This thesis considers cross-layer optimization of multi-hop rad...

Gravitational double layers

International Nuclear Information System (INIS)

Senovilla, José M M

2014-01-01

I analyze the properties of thin shells through which the scalar curvature R is discontinuous in gravity theories with Lagrangian F(R) = R − 2Λ + αR 2 on the bulk. These shells/domain walls are of a new kind because they possess, in addition to the standard energy–momentum tensor, an external energy flux vector, an external scalar pressure/tension and, most exotic of all, another energy–momentum contribution resembling classical dipole distributions on a shell: a double layer. I prove that all these contributions are necessary to make the entire energy–momentum tensor divergence-free. This is the first known occurrence of such a type of double layer in a gravity theory. I present explicit examples in constant-curvature five-dimensional bulks, with a brief study of their properties: new physical behaviors arise. (fast track communications)

Integrated base stations and a method of transmitting data units in a communications system for mobile devices

NARCIS (Netherlands)

Bosch, H.G.P.; Mullender, Sape J.; Narlikar, G.J.; Samuel, L.G.; Yagati, L.N.

2006-01-01

Integrated base stations and a method of transmitting data units in a communications system for mobile devices. In one embodiment, an integrated base station includes a communications processor having a protocol stack configured with a media access control layer and a physical layer.

Location-Aware Cross-Layer Design Using Overlay Watermarks

Directory of Open Access Journals (Sweden)

Paul Ho

2007-04-01

Full Text Available A new orthogonal frequency division multiplexing (OFDM system embedded with overlay watermarks for location-aware cross-layer design is proposed in this paper. One major advantage of the proposed system is the multiple functionalities the overlay watermark provides, which includes a cross-layer signaling interface, a transceiver identification for position-aware routing, as well as its basic role as a training sequence for channel estimation. Wireless terminals are typically battery powered and have limited wireless communication bandwidth. Therefore, efficient collaborative signal processing algorithms that consume less energy for computation and less bandwidth for communication are needed. Transceiver aware of its location can also improve the routing efficiency by selective flooding or selective forwarding data only in the desired direction, since in most cases the location of a wireless host is unknown. In the proposed OFDM system, location information of a mobile for efficient routing can be easily derived when a unique watermark is associated with each individual transceiver. In addition, cross-layer signaling and other interlayer interactive information can be exchanged with a new data pipe created by modulating the overlay watermarks. We also study the channel estimation and watermark removal techniques at the physical layer for the proposed overlay OFDM. Our channel estimator iteratively estimates the channel impulse response and the combined signal vector from the overlay OFDM signal. Cross-layer design that leads to low-power consumption and more efficient routing is investigated.

Signal processing approaches to secure physical layer communications in multi-antenna wireless systems

CERN Document Server

Hong, Y-W Peter; Kuo, C-C Jay

2013-01-01

This book introduces various signal processing approaches to enhance physical layer secrecy in multi-antenna wireless systems. Wireless physical layer secrecy has attracted much attention in recent years due to the broadcast nature of the wireless medium and its inherent vulnerability to eavesdropping. While most articles on physical layer secrecy focus on the information-theoretic aspect, we focus specifically on the signal processing aspects, including beamforming and precoding techniques for data transmission and discriminatory training schemes for channel estimation. The discussions will c

Post Rio Communication Styles for Deliberation

DEFF Research Database (Denmark)

Holm, Jesper; Almlund, Pernille

2015-01-01

The communicative turn in planning, multi-layered governance and governmentality are analytical concepts from various schools of thought to comprehend the emergence of new types of publicprivate politics when it comes to complex, wicked issues such as sustainability or the 3rd wave of public health......: health promotion. The paper explores a research approach to compare two different policy communication tracks in order to conceive various impacts on deliberation. The tracks are constructed along the narratives individual-collective & consensus-conflictual in the discursive framing of political...... communication. We build on an ANT inspired methodology and look into two simultaneously evolving political agendas during the last two decades - sustainability and health promotion - that have framed communication efforts, campaigns and politics in general. How is public participation and deliberation...

Portfolio analysis of layered security measures.

Science.gov (United States)

Chatterjee, Samrat; Hora, Stephen C; Rosoff, Heather

2015-03-01

Layered defenses are necessary for protecting the public from terrorist attacks. Designing a system of such defensive measures requires consideration of the interaction of these countermeasures. In this article, we present an analysis of a layered security system within the lower Manhattan area. It shows how portfolios of security measures can be evaluated through portfolio decision analysis. Consideration is given to the total benefits and costs of the system. Portfolio diagrams are created that help communicate alternatives among stakeholders who have differing views on the tradeoffs between security and economic activity. © 2014 Society for Risk Analysis.

OFDM systems for wireless communications

CERN Document Server

Narasimhamurthy, Adarsh

2010-01-01

Orthogonal Frequency Division Multiplexing (OFDM) systems are widely used in the standards for digital audio/video broadcasting, WiFi and WiMax. Being a frequency-domain approach to communications, OFDM has important advantages in dealing with the frequency-selective nature of high data rate wireless communication channels. As the needs for operating with higher data rates become more pressing, OFDM systems have emerged as an effective physical-layer solution.This short monograph is intended as a tutorial which highlights the deleterious aspects of the wireless channel and presents why OFDM is

Functional Safety Specification of Communication Profile PROFIsafe

Directory of Open Access Journals (Sweden)

Jan Rofar

2006-01-01

Full Text Available Paper maps the trends in area of safety-related communication within PROFIBUS and PROFINET industry networks. There are analyses safety measures and Fail-safe parameters of PROFIsafe profile in version V2 and their localisation in Safety Communication Layer SCL, which guarantees Safety Integrity Level SIL according to standard IEC 61508. The last chapter analyses the reaction in the event of fault during transmission of messages.

Designing a playful communication support tool for persons with aphasia

NARCIS (Netherlands)

Al Mahmud, A.; Ayoola, I.B.I.; Martens, J.B.O.S.; Campos, P.; Graham, N.; George, J.; Nunes, N.; Palanque, P.; Winckler, M.

2011-01-01

Many studies have investigated ways to leverage communication with people with aphasia. Here, a new concept is developed for people with non-severe aphasia in a way that accesses the emotional and unaware layer of a conversation and then communicates certain information to the partner hence;

Blocking-resistant communication through domain fronting

Directory of Open Access Journals (Sweden)

Fifield David

2015-06-01

Full Text Available We describe “domain fronting,” a versatile censorship circumvention technique that hides the remote endpoint of a communication. Domain fronting works at the application layer, using HTTPS, to communicate with a forbidden host while appearing to communicate with some other host, permitted by the censor. The key idea is the use of different domain names at different layers of communication. One domain appears on the “outside” of an HTTPS request—in the DNS request and TLS Server Name Indication—while another domain appears on the “inside”—in the HTTP Host header, invisible to the censor under HTTPS encryption. A censor, unable to distinguish fronted and nonfronted traffic to a domain, must choose between allowing circumvention traffic and blocking the domain entirely, which results in expensive collateral damage. Domain fronting is easy to deploy and use and does not require special cooperation by network intermediaries. We identify a number of hard-to-block web services, such as content delivery networks, that support domain-fronted connections and are useful for censorship circumvention. Domain fronting, in various forms, is now a circumvention workhorse. We describe several months of deployment experience in the Tor, Lantern, and Psiphon circumvention systems, whose domain-fronting transports now connect thousands of users daily and transfer many terabytes per month.

Cross-Layer Adaptive Feedback Scheduling of Wireless Control Systems

Directory of Open Access Journals (Sweden)

Jinxiang Dong

2008-07-01

Full Text Available 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 crosslayer 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 eventdriven 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.

Optimised cross-layer synchronisation schemes for wireless sensor networks

Science.gov (United States)

Nasri, Nejah; Ben Fradj, Awatef; Kachouri, Abdennaceur

2017-07-01

This paper aims at synchronisation between the sensor nodes. Indeed, in the context of wireless sensor networks, it is necessary to take into consideration the energy cost induced by the synchronisation, which can represent the majority of the energy consumed. On communication, an already identified hard point consists in imagining a fine synchronisation protocol which must be sufficiently robust to the intermittent energy in the sensors. Hence, this paper worked on aspects of performance and energy saving, in particular on the optimisation of the synchronisation protocol using cross-layer design method such as synchronisation between layers. Our approach consists in balancing the energy consumption between the sensors and choosing the cluster head with the highest residual energy in order to guarantee the reliability, integrity and continuity of communication (i.e. maximising the network lifetime).

On the nature of the disordered layer produced by ion implantation

International Nuclear Information System (INIS)

Zellama, K.; Germain, P.; Squelard, S.; Bourgoin, J.C.; Piaguet, J.; Robic, J.Y.

1978-01-01

The aim of this communication is to compare some thermodynamic parameters measured in amorphous layers produced by evaporation and in disordered layers produced by ion implantation (which will be called implanted layers). The thermodynamics parameters studied are: the temperature of the annealing stages (reflecting the activation energies for atomic rearrangement) and the activation energy of the growth rate for crystallization. This investigation has been performed in germanium because the crystallization in this material has been extensively studied. (author)

A Review on Human Body Communication: Signal Propagation Model, Communication Performance, and Experimental Issues

Directory of Open Access Journals (Sweden)

Jian Feng Zhao

2017-01-01

Full Text Available Human body communication (HBC, which uses the human body tissue as the transmission medium to transmit health informatics, serves as a promising physical layer solution for the body area network (BAN. The human centric nature of HBC offers an innovative method to transfer the healthcare data, whose transmission requires low interference and reliable data link. Therefore, the deployment of HBC system obtaining good communication performance is required. In this regard, a tutorial review on the important issues related to HBC data transmission such as signal propagation model, channel characteristics, communication performance, and experimental considerations is conducted. In this work, the development of HBC and its first attempts are firstly reviewed. Then a survey on the signal propagation models is introduced. Based on these models, the channel characteristics are summarized; the communication performance and selection of transmission parameters are also investigated. Moreover, the experimental issues, such as electrodes and grounding strategies, are also discussed. Finally, the recommended future studies are provided.

Design and analysis of three-layer-core optical fiber

Science.gov (United States)

Zheng, Siwen; Liu, Yazhuo; Chang, Guangjian

2018-03-01

A three-layer-core single-mode large-mode-area fiber is investigated. The three-layer structure in the core, which is composed of a core-index layer, a cladding-index layer, and a depression-index layer, could achieve a large effective area Aeff while maintaining an ultralow bending loss without deteriorating cutoff behaviors. The single-mode large mode area of 100 to 330 μm2 could be achieved in the fiber. The effective area Aeff can be further enlarged by adjusting the layer parameters. Furthermore, the bending property could be improved in this three-layer-core structure. The bending loss could decrease by 2 to 4 orders of magnitude compared with the conventional step-index fiber with the same Aeff. These characteristics of three-layer-core fiber suggest that it can be used in large-mode-area wide-bandwidth high-capacity transmission or high-power optical fiber laser and amplifier in optical communications, which could be used for the basic physical layer structure of big data storage, reading, calculation, and transmission applications.

Brief communication: Improved simulation of the present-day Greenland firn layer (1960-2016)

Science.gov (United States)

Ligtenberg, Stefan R. M.; Kuipers Munneke, Peter; Noël, Brice P. Y.; van den Broeke, Michiel R.

2018-05-01

By providing pore space for storage or refreezing of meltwater, the Greenland ice sheet firn layer strongly modulates runoff. Correctly representing the firn layer is therefore crucial for Greenland (surface) mass balance studies. Here, we present a simulation of the Greenland firn layer with the firn model IMAU-FDM forced by the latest output of the regional climate model RACMO2, version 2.3p2. In the percolation zone, much improved agreement is found with firn density and temperature observations. A full simulation of Greenland firn at high temporal (10 days) and spatial (11 km) resolution is available for the period 1960-2016.

Evaluating Application-Layer Traffic Optimization Cost Metrics for P2P Multimedia Streaming

DEFF Research Database (Denmark)

Poderys, Justas; Soler, José

2017-01-01

To help users of P2P communication systems perform better-than-random selection of communication peers, Internet Engineering Task Force standardized the Application Layer Traffic Optimization (ALTO) protocol. The ALTO provided data-routing cost metric, can be used to rank peers in P2P communicati...

Evolutionary dynamics of complex communications networks

CERN Document Server

Karyotis, Vasileios; Papavassiliou, Symeon

2013-01-01

Until recently, most network design techniques employed a bottom-up approach with lower protocol layer mechanisms affecting the development of higher ones. This approach, however, has not yielded fascinating results in the case of wireless distributed networks. Addressing the emerging aspects of modern network analysis and design, Evolutionary Dynamics of Complex Communications Networks introduces and develops a top-bottom approach where elements of the higher layer can be exploited in modifying the lowest physical topology-closing the network design loop in an evolutionary fashion similar to

Trusted communications with physical layer security for 5G and beyond

CERN Document Server

Duong, Trung Q; Poor, H Vincent

2017-01-01

Securely transferring confidential information over a wireless network is a challenging task. This book addresses security issues, not only for 5G but also beyond, using physical layer security technology and techniques.

Speaker identification for the improvement of the security communication between law enforcement units

Science.gov (United States)

Tovarek, Jaromir; Partila, Pavol

2017-05-01

This article discusses the speaker identification for the improvement of the security communication between law enforcement units. The main task of this research was to develop the text-independent speaker identification system which can be used for real-time recognition. This system is designed for identification in the open set. It means that the unknown speaker can be anyone. Communication itself is secured, but we have to check the authorization of the communication parties. We have to decide if the unknown speaker is the authorized for the given action. The calls are recorded by IP telephony server and then these recordings are evaluate using classification If the system evaluates that the speaker is not authorized, it sends a warning message to the administrator. This message can detect, for example a stolen phone or other unusual situation. The administrator then performs the appropriate actions. Our novel proposal system uses multilayer neural network for classification and it consists of three layers (input layer, hidden layer, and output layer). A number of neurons in input layer corresponds with the length of speech features. Output layer then represents classified speakers. Artificial Neural Network classifies speech signal frame by frame, but the final decision is done over the complete record. This rule substantially increases accuracy of the classification. Input data for the neural network are a thirteen Mel-frequency cepstral coefficients, which describe the behavior of the vocal tract. These parameters are the most used for speaker recognition. Parameters for training, testing and validation were extracted from recordings of authorized users. Recording conditions for training data correspond with the real traffic of the system (sampling frequency, bit rate). The main benefit of the research is the system developed for text-independent speaker identification which is applied to secure communication between law enforcement units.

Cross-Layer Design Approach for Power Control in Mobile Ad Hoc Networks

Directory of Open Access Journals (Sweden)

A. Sarfaraz Ahmed

2015-03-01

Full Text Available In mobile ad hoc networks, communication among mobile nodes occurs through wireless medium The design of ad hoc network protocol, generally based on a traditional “layered approach”, has been found ineffective to deal with receiving signal strength (RSS-related problems, affecting the physical layer, the network layer and transport layer. This paper proposes a design approach, deviating from the traditional network design, toward enhancing the cross-layer interaction among different layers, namely physical, MAC and network. The Cross-Layer design approach for Power control (CLPC would help to enhance the transmission power by averaging the RSS values and to find an effective route between the source and the destination. This cross-layer design approach was tested by simulation (NS2 simulator and its performance over AODV was found to be better.

Comparison of TCeMA and TDMA for Inter-Satellite Communications using OPNET Simulation

Science.gov (United States)

Hain, Regina Rosales; Ramanathan, Ram; Bergamo, Marcos; Wallett, Thomas M.

2003-01-01

A robust data link protocol, enabling unique physical and MAC layer technologies and sub-network level protocols, is needed in order to take advantage of the full potential of using both TDMA and CDMA in a satellite communication network. A novel MAC layer protocol, TDMA with CDMA-encoding multiple access (TCeMA) integrated with null-steered digital beam-forming spatial multiplexing, is investigated to support flexible spacecraft communications. Abstract models of the TCeMA and TDMA processes are developed in OPNFiT and a comparison of the performances of TCeMA and TDMA in a satellite network simulation are made. TCeMA provides the better connectivity and capacity with respect to TDMA for satellite communication traffic.

Acemind new indoor full duplex optical wireless communication prototype

Science.gov (United States)

Bouchet, Olivier; Perrufel, Micheline; Topsu, Suat; Guan, Hongyu

2016-09-01

For over a century and Mr. Guglielmo Marconi invention, systems using radio waves have controlled over wireless telecommunication solutions; from Amplitude Modulation (AM) radio products to satellite communications for instance. But beyond an increasingly negative opinion face to radio waves and radio spectrum availability more and more reduced; there is an unprecedented opportunity with LED installation in displays and lighting to provide optical wireless communication solutions. As a result, technologically mature solutions are already commercially available for services such as Location Based Services (LBS), broadcast diffusion or Intelligent Transport Services (ITS). Pending finalization of the standard review process IEEE 802.15.7 r1, our paper presents the results of the European collaborative project named "ACEMIND". It offers an indoor bilateral optical wireless communication prototype having the following characteristics: use of the existing electrical infrastructure, through judicious combination with Light Fidelity (LiFi), Power Line Communication (PLC) and Ethernet to reduce the implementation cost. We propose a bilateral optical wireless communication even when the light is switched off by using Visible Light Communication (VLC) and Infra-Red Communication (IRC) combined to a remote optical switch. Dimensionally optimized LiFi module is presented in order to offer the possibility for integration inside a laptop. Finally, there is operational mechanism implementation such as OFDM/DMT to increase throughput. After the introduction, we will present the results of a market study from Orange Labs customers about their opinion on LiFi components. Then we will detail the LiFi prototype, from the physical layer aspect to MAC layer before concluding on commercial development prospects.

A Performance Evaluation of NACK-Oriented Protocols as the Foundation of Reliable Delay- Tolerant Networking Convergence Layers

Science.gov (United States)

Iannicca, Dennis; Hylton, Alan; Ishac, Joseph

2012-01-01

Delay-Tolerant Networking (DTN) is an active area of research in the space communications community. DTN uses a standard layered approach with the Bundle Protocol operating on top of transport layer protocols known as convergence layers that actually transmit the data between nodes. Several different common transport layer protocols have been implemented as convergence layers in DTN implementations including User Datagram Protocol (UDP), Transmission Control Protocol (TCP), and Licklider Transmission Protocol (LTP). The purpose of this paper is to evaluate several stand-alone implementations of negative-acknowledgment based transport layer protocols to determine how they perform in a variety of different link conditions. The transport protocols chosen for this evaluation include Consultative Committee for Space Data Systems (CCSDS) File Delivery Protocol (CFDP), Licklider Transmission Protocol (LTP), NACK-Oriented Reliable Multicast (NORM), and Saratoga. The test parameters that the protocols were subjected to are characteristic of common communications links ranging from terrestrial to cis-lunar and apply different levels of delay, line rate, and error.

A High Speed Mobile Communication System implementing Bicasting Architecture on the IP Layer

OpenAIRE

Yamada, Kazuhiro

2012-01-01

Having a broadband connection on high speed rails is something that business travelers want most. Increasing number of passengers is requesting even higher access speeds. We are proposing the Media Convergence System as an ideal communication system for future high speed mobile entities. The Media Convergence System recognizes plural wireless communication media between the ground network and each train, and then traffic is load-balanced over active media which varies according to circumstanc...

Study of LiTiMg-ferrite radome for the application of satellite communication

International Nuclear Information System (INIS)

Saxena, Naveen Kumar; Kumar, Nitendar; Pourush, P.K.S.

2010-01-01

In this paper the characteristics of LiTiMg-ferrite radome are presented. A thin layer of LiTiMg-ferrite is used as superstrate or radome, which controls the radiation, reception, and scattering from a printed antenna or array by applying a dc magnetic bias field in the plane of the ferrite, orthogonal to the RF magnetic field. In this analysis absorbing and transmission power coefficients are calculated to obtain the power loss and transmitted power through the radome layer respectively. The absorbing power coefficient verifies the switching behavior of radome for certain range of applied external magnetic field (Ho), which depends on the resonance width parameter (ΔH) of ferrite material. By properly choosing the bias field, electromagnetic wave propagation in the ferrite layer can be made zero or negligible over a certain frequency range, resulting in switching behavior of the ferrite layer. In this communication we also show precise preparation of radome layer and present its electric and magnetic properties along with its Curie temperature, which shows the working efficiency of layer under extreme situation. This radome layer can be very useful for the sensitive and smart communication systems.

Design of interstellar digital communication links: Some insights from communication engineering

Science.gov (United States)

Messerschmitt, David G.; Morrison, Ian S.

2012-09-01

The design of an end-to-end digital interstellar communication system at radio frequencies is discussed, drawing on the disciplines of digital communication engineering and computer network engineering in terrestrial and near-space applications. One goal is a roadmap to the design of such systems, aimed at future designers of either receivers (SETI) or transmitters (METI). In particular we emphasize the implications arising from the impossibility of coordination between transmitter and receiver prior to a receiver's search for a signal. A system architecture based on layering, as commonly used in network and software design, assists in organizing and categorizing the various design issues and identifying dependencies. Implications of impairments introduced in the interstellar medium, such as dispersion, scattering, Doppler, noise, and signal attenuation are discussed. Less fundamental (but nevertheless influential) design issues are the motivations of the transmitter designers and associated resource requirements at both transmitter and receiver. Unreliability is inevitably imposed by non-idealities in the physical communication channel, and this unreliability will have substantial implications for those seeking to convey interstellar messages.

Satellite Communications Using Commercial Protocols

Science.gov (United States)

Ivancic, William D.; Griner, James H.; Dimond, Robert; Frantz, Brian D.; Kachmar, Brian; Shell, Dan

2000-01-01

NASA Glenn Research Center has been working with industry, academia, and other government agencies in assessing commercial communications protocols for satellite and space-based applications. In addition, NASA Glenn has been developing and advocating new satellite-friendly modifications to existing communications protocol standards. This paper summarizes recent research into the applicability of various commercial standard protocols for use over satellite and space- based communications networks as well as expectations for future protocol development. It serves as a reference point from which the detailed work can be readily accessed. Areas that will be addressed include asynchronous-transfer-mode quality of service; completed and ongoing work of the Internet Engineering Task Force; data-link-layer protocol development for unidirectional link routing; and protocols for aeronautical applications, including mobile Internet protocol routing for wireless/mobile hosts and the aeronautical telecommunications network protocol.

The Peace System - As a self-referential communication system

Directory of Open Access Journals (Sweden)

Gorm Harste

2013-11-01

Full Text Available Peace communication as diplomatic communication is an often neglected phenomenon in social and political theory that concerns problems of international order, justice and peace. Political philosophy seldom embarks on the theme with more than a few comments. Yet, throughout history, diplomacy has a strong record not only for negotiations but also for social learning processes about communication codes. Many codes of respect, trust, expression and listening have a top-down history from aristocratic circles to broader social layers. However, the article argues that communication codes of peace developed in opposition to violence and war exactly when they transgress dividing lines allowing for cross-cultural and even cross-stratified communication. The article’s main point is to describe how such communication codes about peace and diplomacy can be described in recent social theory of communication, and to get some added value in this respect, Niklas Luhmann’s theory of self-referential communication systems has been applied.

Investigating the Performance of the MPT Multipath Communication Library in IPv4 and IPv6

Directory of Open Access Journals (Sweden)

Béla Almási

2016-01-01

Full Text Available The currently used mobile devices (laptops, tablets, mobile phones contain many built-in network cards for communication (e.g. Wi-Fi, 3G, Bluetooth, etc.. A natural request could be combining the resources of the different network connection possibilities in order to increase the throughput of the communication. Unfortunately the standard IP communication technology does not support it: the communication is restricted to one IP address (i.e. to one interface. The Multipath TCP (MPTCP specification (appeared in January 2013 offers a Transport layer solution of using more than one interface in a TCP communication session. In this paper we investigate a Network layer solution. The MPT multipath communication library opens the multipath communication possibility in the Network layer. Using the MPT library, applications built on the UDP protocol are also able to perform multipath communication. The MPT library was developed by using a full dual-stack technology, which means the MPT based multipath environment can be used both in IPv4 and IPv6. Protocol version change is also possible: an IPv6 based application is able to run in an IPv4 multipath environment, and an IPv4 application can be used in an IPv6 multipath environment. In this paper we give a short overview on the MPT communication library’s working mechanism and detailed numerical examples will be shown to present how the MPT library aggregates the paths’ throughput in IPv4 and IPv6 environments. The main contribution of the paper is to demonstrate the effective throughput aggregation property of the MPT library in IPv6 and in mixed (i.e. protocol version change environments.

Secure electronic commerce communication system based on CA

Science.gov (United States)

Chen, Deyun; Zhang, Junfeng; Pei, Shujun

2001-07-01

In this paper, we introduce the situation of electronic commercial security, then we analyze the working process and security for SSL protocol. At last, we propose a secure electronic commerce communication system based on CA. The system provide secure services such as encryption, integer, peer authentication and non-repudiation for application layer communication software of browser clients' and web server. The system can implement automatic allocation and united management of key through setting up the CA in the network.

Climate change and ozone layer protection

International Nuclear Information System (INIS)

Anon.

1991-01-01

This conference is composed of 27 communications of which the following main themes are: general approach to the problems of climatic change, greenhouse effect and ozone layer; France, Cameroon and Switzerland examples of energy conservation and greenhouse gas reduction; energy conservation measures and policies for dwellings, transport, industry, agriculture and food industry with a global aspect of reducing greenhouse gas emissions; CFC utilization effects on environment and alternatives to CFC utilization

Optimized Interface Diversity for Ultra-Reliable Low Latency Communication (URLLC)

DEFF Research Database (Denmark)

Nielsen, Jimmy Jessen; Liu, Rongkuan; Popovski, Petar

2017-01-01

An important ingredient of the future 5G systems will be Ultra-Reliable Low-Latency Communication (URLLC). A way to offer URLLC without intervention in the baseband/PHY layer design is to use interface diversity and integrate multiple communication interfaces, each interface based on a different...... technology. Our approach is to use rateless codes to seamlessly distribute coded payload and redundancy data across multiple available communication interfaces. We formulate an optimization problem to find the payload allocation weights that maximize the reliability at specific target latency values...

Efficient SCT Protocol for Post Disaster Communication

Science.gov (United States)

Ramesh, T. K.; Giriraja, C. V.

2017-08-01

Natural and catastrophic disasters can cause damage to the communication system, the damage may be complete or it may be partial. In such areas communication and exchange of information plays a very important role and become difficult to happen in such situations. So, the rescue systems should be installed in those areas for the rescue operations and to take important decisions about how to make a connection from there to the outside world. Wireless communication network architecture should be setup in disaster areas for the communication to happen and to gather information. Wireless ad-hoc network architecture is proposed in this paper with access nodes. These access nodes acts as hotspot for certain area in which they are set up such that the Wi-Fi capable devices get connected to them for communication to happen. If the mobile battery is drained in such situations wireless charging using microwave is shown in this paper. Performance analysis of the communication transport layer protocols is shown and Efficient SCTP (ESTP) algorithm is developed which shows better results in terms of cumulative packet loss.

Layered Architectures for Quantum Computers and Quantum Repeaters

Science.gov (United States)

Jones, Nathan C.

This chapter examines how to organize quantum computers and repeaters using a systematic framework known as layered architecture, where machine control is organized in layers associated with specialized tasks. The framework is flexible and could be used for analysis and comparison of quantum information systems. To demonstrate the design principles in practice, we develop architectures for quantum computers and quantum repeaters based on optically controlled quantum dots, showing how a myriad of technologies must operate synchronously to achieve fault-tolerance. Optical control makes information processing in this system very fast, scalable to large problem sizes, and extendable to quantum communication.

A high throughput data acquisition and processing model for applications based on GPUs

International Nuclear Information System (INIS)

Nieto, J.; Arcas, G. de; Ruiz, M.; Castro, R.; Vega, J.; Guillen, P.

2015-01-01

Highlights: • Implementation of a direct communication path between a data acquisition NI FlexRIO device and a NVIDIA GPU device. • Customization of a Linux Kernel Open Driver (NI FlexRIO) and a C API Interface for work con NVIDIA RDMA GPUDirect. • Performance evaluation with respect to traditional model that use CPU as buffer data allocation. - Abstract: There is an increasing interest in the use of GPU technologies for real time analysis in fusion devices. The availability of high bandwidth interfaces has made them a very cost effective alternative not only for high volume data analysis or simulation, and commercial products are available for some interest areas. However from the point of view of their application in real time scenarios, there are still some issues under analysis, such as the possibility to improve the data throughput inside a discrete system consisting of data acquisition devices (DAQ) and GPUs. This paper addresses the possibility of using peer to peer data communication between DAQ devices and GPUs sharing the same PCIexpress bus to implement continuous real time acquisition and processing systems where data transfers require minimum CPU intervention. This technology eliminates unnecessary system memory copies and lowers CPU overhead, avoiding bottleneck when the system uses the main system memory.

A high throughput data acquisition and processing model for applications based on GPUs

Energy Technology Data Exchange (ETDEWEB)

Nieto, J., E-mail: jnieto@sec.upm.es [Instrumentation and Applied Acoustic Research Group, Technical University of Madrid (UPM), Madrid (Spain); Arcas, G. de; Ruiz, M. [Instrumentation and Applied Acoustic Research Group, Technical University of Madrid (UPM), Madrid (Spain); Castro, R.; Vega, J. [Data acquisition Group EURATOM/CIEMAT Association for Fusion, Madrid (Spain); Guillen, P. [Instrumentation and Applied Acoustic Research Group, Technical University of Madrid (UPM), Madrid (Spain)

2015-10-15

Highlights: • Implementation of a direct communication path between a data acquisition NI FlexRIO device and a NVIDIA GPU device. • Customization of a Linux Kernel Open Driver (NI FlexRIO) and a C API Interface for work con NVIDIA RDMA GPUDirect. • Performance evaluation with respect to traditional model that use CPU as buffer data allocation. - Abstract: There is an increasing interest in the use of GPU technologies for real time analysis in fusion devices. The availability of high bandwidth interfaces has made them a very cost effective alternative not only for high volume data analysis or simulation, and commercial products are available for some interest areas. However from the point of view of their application in real time scenarios, there are still some issues under analysis, such as the possibility to improve the data throughput inside a discrete system consisting of data acquisition devices (DAQ) and GPUs. This paper addresses the possibility of using peer to peer data communication between DAQ devices and GPUs sharing the same PCIexpress bus to implement continuous real time acquisition and processing systems where data transfers require minimum CPU intervention. This technology eliminates unnecessary system memory copies and lowers CPU overhead, avoiding bottleneck when the system uses the main system memory.

MIMO Communication for Cellular Networks

CERN Document Server

Huang, Howard; Venkatesan, Sivarama

2012-01-01

As the theoretical foundations of multiple-antenna techniques evolve and as these multiple-input multiple-output (MIMO) techniques become essential for providing high data rates in wireless systems, there is a growing need to understand the performance limits of MIMO in practical networks. To address this need, MIMO Communication for Cellular Networks presents a systematic description of MIMO technology classes and a framework for MIMO system design that takes into account the essential physical-layer features of practical cellular networks. In contrast to works that focus on the theoretical performance of abstract MIMO channels, MIMO Communication for Cellular Networks emphasizes the practical performance of realistic MIMO systems. A unified set of system simulation results highlights relative performance gains of different MIMO techniques and provides insights into how best to use multiple antennas in cellular networks under various conditions. MIMO Communication for Cellular Networks describes single-user,...

Wireless physical layer security

Science.gov (United States)

Poor, H. Vincent; Schaefer, Rafael F.

2017-01-01

Security in wireless networks has traditionally been considered to be an issue to be addressed separately from the physical radio transmission aspects of wireless systems. However, with the emergence of new networking architectures that are not amenable to traditional methods of secure communication such as data encryption, there has been an increase in interest in the potential of the physical properties of the radio channel itself to provide communications security. Information theory provides a natural framework for the study of this issue, and there has been considerable recent research devoted to using this framework to develop a greater understanding of the fundamental ability of the so-called physical layer to provide security in wireless networks. Moreover, this approach is also suggestive in many cases of coding techniques that can approach fundamental limits in practice and of techniques for other security tasks such as authentication. This paper provides an overview of these developments.

MAC layer security issues in wireless mesh networks

Science.gov (United States)

Reddy, K. Ganesh; Thilagam, P. Santhi

2016-03-01

Wireless Mesh Networks (WMNs) have emerged as a promising technology for a broad range of applications due to their self-organizing, self-configuring and self-healing capability, in addition to their low cost and easy maintenance. Securing WMNs is more challenging and complex issue due to their inherent characteristics such as shared wireless medium, multi-hop and inter-network communication, highly dynamic network topology and decentralized architecture. These vulnerable features expose the WMNs to several types of attacks in MAC layer. The existing MAC layer standards and implementations are inadequate to secure these features and fail to provide comprehensive security solutions to protect both backbone and client mesh. Hence, there is a need for developing efficient, scalable and integrated security solutions for WMNs. In this paper, we classify the MAC layer attacks and analyze the existing countermeasures. Based on attacks classification and countermeasures analysis, we derive the research directions to enhance the MAC layer security for WMNs.

Cortical layers, rhythms and BOLD signals.

Science.gov (United States)

Scheeringa, René; Fries, Pascal

2017-11-03

This review investigates how laminar fMRI can complement insights into brain function derived from the study of rhythmic neuronal synchronization. Neuronal synchronization in various frequency bands plays an important role in neuronal communication between brain areas, and it does so on the backbone of layer-specific interareal anatomical projections. Feedforward projections originate predominantly in supragranular cortical layers and terminate in layer 4, and this pattern is reflected in inter-laminar and interareal directed gamma-band influences. Thus, gamma-band synchronization likely subserves feedforward signaling. By contrast, anatomical feedback projections originate predominantly in infragranular layers and terminate outside layer 4, and this pattern is reflected in inter-laminar and interareal directed alpha- and/or beta-band influences. Thus, alpha-beta band synchronization likely subserves feedback signaling. Furthermore, these rhythms explain part of the BOLD signal, with independent contributions of alpha-beta and gamma. These findings suggest that laminar fMRI can provide us with a potentially useful method to test some of the predictions derived from the study of neuronal synchronization. We review central findings regarding the role of layer-specific neuronal synchronization for brain function, and regarding the link between neuronal synchronization and the BOLD signal. We discuss the role that laminar fMRI could play by comparing it to invasive and non-invasive electrophysiological recordings. Compared to direct electrophysiological recordings, this method provides a metric of neuronal activity that is slow and indirect, but that is uniquely non-invasive and layer-specific with potentially whole brain coverage. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Adaptive Communication Techniques for the Internet of Things

Directory of Open Access Journals (Sweden)

Peng Du

2013-03-01

Full Text Available The vision for the Internet of Things (IoT demands that material objects acquire communications and computation capabilities and become able to automatically identify themselves through standard protocols and open systems, using the Internet as their foundation. Yet, several challenges still must be addressed for this vision to become a reality. A core ingredient in such development is the ability of heterogeneous devices to communicate adaptively so as to make the best of limited spectrum availability and cope with competition which is inevitable as more and more objects connect to the system. This survey provides an overview of current developments in this area, placing emphasis on wireless sensor networks that can provide IoT capabilities for material objects and techniques that can be used in the context of systems employing low-power versions of the Internet Protocol (IP stack. The survey introduces a conceptual model that facilitates the identification of opportunities for adaptation in each layer of the network stack. After a detailed discussion of specific approaches applicable to particular layers, we consider how sharing information across layers can facilitate further adaptation. We conclude with a discussion of future research directions.

The Peace System – As a Self-Referential Communication System

DEFF Research Database (Denmark)

Harste, Gorm

2013-01-01

developed in opposition to violence and war exactly when they transgress dividing lines allowing for cross-cultural and even cross-stratified communication. The article’s main point is to describe how such communication codes about peace and diplomacy can be described in recent social theory......Peace communication as diplomatic communication is an often neglected phenomenon in social and political theory that concerns problems of international order, justice and peace. Political philosophy seldom embarks on the theme with more than a few comments. Yet, throughout history, diplomacy has...... a strong record not only for negotiations but also for social learning processes about communication codes. Many codes of respect, trust, expression and listening have a top-down history from aristocratic circles to broader social layers. However, the article argues that communication codes of peace...

Collaboration Layer for Robots in Mobile Ad-hoc Networks

DEFF Research Database (Denmark)

Borch, Ole; Madsen, Per Printz; Broberg, Jacob Honor´e

2009-01-01

In many applications multiple robots in Mobile Ad-hoc Networks are required to collaborate in order to solve a task. This paper shows by proof of concept that a Collaboration Layer can be modelled and designed to handle the collaborative communication, which enables robots in small to medium size...

Energy consumption and quality of service in WBAN: A performance evaluation between cross-layer and IEEE802.15.4

OpenAIRE

Correa-Chica, Juan Camilo; Botero-Vega, Juan Felipe; Gaviria-Gómez, Natalia

2017-01-01

Abstract Different communication schemes for Wireless Body Area Networks (WBAN) pretend to achieve a fair tradeoff between efficient energy consumption and the accomplishment of performance metrics. Among those schemes are the Cross-layer protocols that constitute a good choice to achieve the aforementioned tradeoff by introducing novel protocol techniques which are away from the traditional communications model. In this work we assessed the performance of a WBAN cross-layer protocol stack by...

Verifying Quality of Service of ARCnet Based ATOMOS Communication System for Integrated Ship Control

DEFF Research Database (Denmark)

Nielsen, N.N.; Nielsen, Jens Frederik Dalsgaard; Schiøler, Henrik

point) layer. An important characteristic of the communication system is that the functionality and timing must be verifiable in order to satisfy requirements from classification companies like Lloyds and Norsk Veritas. By including Service Categories, Traffic Descriptors and Quality of Service concepts......As part of the ATOMOS project (Funded by EU, DG VII) a reliable communication system with predictable behaviour has been designed. The selected solution is a network based on redundant ARCnet segments extended with an EN50170 compliant fieldbus based layer on top of an ARCnet SAP (service access...

Verifying Quality of Service of ARCnet Based ATOMOS Communication System for Integrated Ship Control

DEFF Research Database (Denmark)

Nielsen, N.N.; Nielsen, Jens Frederik Dalsgaard; Schiøler, Henrik

1999-01-01

point) layer. An important characteristic of the communication system is that the functionality and timing must be verifiable in order to satisfy requirements from classification companies like Lloyds and Norsk Veritas. By including Service Categories, Traffic Descriptors and Quality of Service concepts......As part of the ATOMOS project (Funded by EU, DG VII) a reliable communication system with predictable behaviour has been designed. The selected solution is a network based on redundant ARCnet segments extended with an EN50170 compliant fieldbus based layer on top of an ARCnet SAP (service access...

Cross-Layer QoS Control for Video Communications over Wireless Ad Hoc Networks

Directory of Open Access Journals (Sweden)

Pei Yong

2005-01-01

Full Text Available Assuming a wireless ad hoc network consisting of homogeneous video users with each of them also serving as a possible relay node for other users, we propose a cross-layer rate-control scheme based on an analytical study of how the effective video transmission rate is affected by the prevailing operating parameters, such as the interference environment, the number of transmission hops to a destination, and the packet loss rate. Furthermore, in order to provide error-resilient video delivery over such wireless ad hoc networks, a cross-layer joint source-channel coding (JSCC approach, to be used in conjunction with rate-control, is proposed and investigated. This approach attempts to optimally apply the appropriate channel coding rate given the constraints imposed by the effective transmission rate obtained from the proposed rate-control scheme, the allowable real-time video play-out delay, and the prevailing channel conditions. Simulation results are provided which demonstrate the effectiveness of the proposed cross-layer combined rate-control and JSCC approach.

Temperature-dependent layer breathing modes in two-dimensional materials

Science.gov (United States)

Maity, Indrajit; Maiti, Prabal K.; Jain, Manish

2018-04-01

Relative out-of-plane displacements of the constituent layers of two-dimensional materials give rise to unique low-frequency breathing modes. By computing the height-height correlation functions from molecular dynamics simulations, we show that the layer breathing modes (LBMs) can be mapped consistently to vibrations of a simple linear chain model. Our calculated thickness dependence of LBM frequencies for few-layer (FL) graphene and molybdenum disulfide (MoS2) are in excellent agreement with available experiments. Our results show a redshift of LBM frequency with an increase in temperature, which is a direct consequence of anharmonicities present in the interlayer interaction. We also predict the thickness and temperature dependence of LBM frequencies for FL hexagonal boron nitride. Our Rapid Communication provides a simple and efficient way to probe the interlayer interaction for layered materials and their heterostructures with the inclusion of anharmonic effects.

Rendering Intelligence at Physical Layer for Smart Addressing and Multiple Access

DEFF Research Database (Denmark)

Sanyal, Rajarshi; Prasad, Ramjee; Cianca, Ernestina

2010-01-01

addressing of a node. For a typical closed user group type of network, we propose a multiple access mechanism and network topology which will not only eliminate the need of intelligent core network equipments in the network area , but to use this intelligent physical layer to directly reach any node over......The primary objective of this work is to propose a technique of wireless communication, where we render intelligence to the physical layer. We aim to realize a physical layer that can take part in some processes which is otherwise confined to higher layer signalling activities, like for example...... the fundamentals behind the proposed multiple access scheme and draws out the benefits compared to the existing multiple access processes based on cellular approach....

Cross Layer Interference Management in Wireless Biomedical Networks

Directory of Open Access Journals (Sweden)

Emmanouil G. Spanakis

2014-04-01

Full Text Available Interference, in wireless networks, is a central phenomenon when multiple uncoordinated links share a common communication medium. The study of the interference channel was initiated by Shannon in 1961 and since then this problem has been thoroughly elaborated at the Information theoretic level but its characterization still remains an open issue. When multiple uncoordinated links share a common medium the effect of interference is a crucial limiting factor for network performance. In this work, using cross layer cooperative communication techniques, we study how to compensate interference in the context of wireless biomedical networks, where many links transferring biomedical or other health related data may be formed and suffer from all other interfering transmissions, to allow successful receptions and improve the overall network performance. We define the interference limited communication range to be the critical communication region around a receiver, with a number of surrounding interfering nodes, within which a successful communication link can be formed. Our results indicate that we can achieve more successful transmissions by adapting the transmission rate and power, to the path loss exponent, and the selected mode of the underline communication technique allowing interference mitigation and when possible lower power consumption and increase achievable transmission rates.

A Generalized Method for Vertical Profiles of Mean Layer Values of Meteorological Variables

Science.gov (United States)

2015-09-01

American Meteorological Society, Boston, MA. Ray C. Private communication, 2013. Reen B. Private communication, 2015. STANAG 4061 (Edition 4), North ...STANAG 4082 (Edition 2), North Atlantic Treaty Organization - Military Agency for Standardization, Adoption of a Standard Artillery Computer...missing or bad data indicator. Also, balis refers to arrays for individual layer values and balmsg refers to arrays for METB3 type values. Pass in

Analysis of SCTP and TCP based communication in high-speed clusters

International Nuclear Information System (INIS)

Kozlovszky, M.; Berceli, T.; Kutor, L.

2006-01-01

Performance and financial constraints are pushing modern DAQs (Data Acquisition Systems) to use distributed cluster environments instead of monolith one-box systems. Inside clusters application communication layers should support outstanding high performance requirements. We are currently investigating different network protocols that could meet the requirements of high speed/low latency peer-to-peer communication within DAQ clusters. We have carried out various performance measurements with TCP and SCTP over Fast and Gigabit Ethernet. We are focusing on Ethernet Technologies, because this transport medium is broad deployed, cost efficient and it has much better cost/throughput ratio than other available communication alternatives (e.g.: Myrinet, Infiniband). During this study, a protocol performance measurement application with different peer transport components has been developed. In the first part of the paper, we give a short comparison of the two protocols (SCTP and TCP), and an introduction of the transport layer structure developed. Later on we discuss the performance results of single/multi-stream peer-to-peer communication, give overview about application code transition possibilities from application developer point of view between the two protocols, and draw conclusions about usability

The case for a network protocol isolation layer

KAUST Repository

Il Choi, Jung

2009-01-01

Network protocols are typically designed and tested individually. In practice, however, applications use multiple protocols concurrently. This discrepancy can lead to failures from unanticipated interactions between protocols. In this paper, we argue that sensor network communication stacks should have an isolation layer, whose purpose is to make each protocol\\'s perception of the wireless channel independent of what other protocols are running. We identify two key mechanisms the isolation layer must provide: shared collision avoidance and fair channel allocation. We present an example design of an isolation layer that builds on the existing algorithms of grant-to-send and fair queueing. However, the complexities of wireless make these mechanisms insufficient by themselves. We therefore propose two new mechanisms that address these limitations: channel decay and fair cancellation. Incorporating these new mechanisms reduces the increase in end-to-end delivery cost associated with concurrently operating two protocols by more than 60%. The isolation layer improves median protocol fairness from 0.52 to 0.96 in Jain\\'s fairness index. Together, these results show that using an isolation layer makes protocols more efficient and robust. Copyright 2009 ACM.

The case for a network protocol isolation layer

KAUST Repository

Il Choi, Jung; Kazandjieva, Maria A.; Jain, Mayank; Levis, Philip

2009-01-01

Network protocols are typically designed and tested individually. In practice, however, applications use multiple protocols concurrently. This discrepancy can lead to failures from unanticipated interactions between protocols. In this paper, we argue that sensor network communication stacks should have an isolation layer, whose purpose is to make each protocol's perception of the wireless channel independent of what other protocols are running. We identify two key mechanisms the isolation layer must provide: shared collision avoidance and fair channel allocation. We present an example design of an isolation layer that builds on the existing algorithms of grant-to-send and fair queueing. However, the complexities of wireless make these mechanisms insufficient by themselves. We therefore propose two new mechanisms that address these limitations: channel decay and fair cancellation. Incorporating these new mechanisms reduces the increase in end-to-end delivery cost associated with concurrently operating two protocols by more than 60%. The isolation layer improves median protocol fairness from 0.52 to 0.96 in Jain's fairness index. Together, these results show that using an isolation layer makes protocols more efficient and robust. Copyright 2009 ACM.

Global forward-predicting dynamic routing for traffic concurrency space stereo multi-layer scale-free network

International Nuclear Information System (INIS)

Xie Wei-Hao; Zhou Bin; Liu En-Xiao; Lu Wei-Dang; Zhou Ting

2015-01-01

Many real communication networks, such as oceanic monitoring network and land environment observation network, can be described as space stereo multi-layer structure, and the traffic in these networks is concurrent. Understanding how traffic dynamics depend on these real communication networks and finding an effective routing strategy that can fit the circumstance of traffic concurrency and enhance the network performance are necessary. In this light, we propose a traffic model for space stereo multi-layer complex network and introduce two kinds of global forward-predicting dynamic routing strategies, global forward-predicting hybrid minimum queue (HMQ) routing strategy and global forward-predicting hybrid minimum degree and queue (HMDQ) routing strategy, for traffic concurrency space stereo multi-layer scale-free networks. By applying forward-predicting strategy, the proposed routing strategies achieve better performances in traffic concurrency space stereo multi-layer scale-free networks. Compared with the efficient routing strategy and global dynamic routing strategy, HMDQ and HMQ routing strategies can optimize the traffic distribution, alleviate the number of congested packets effectively and reach much higher network capacity. (paper)

System Design for Nano-Network Communications

Science.gov (United States)

ShahMohammadian, Hoda

The potential applications of nanotechnology in a wide range of areas necessities nano-networking research. Nano-networking is a new type of networking which has emerged by applying nanotechnology to communication theory. Therefore, this dissertation presents a framework for physical layer communications in a nano-network and addresses some of the pressing unsolved challenges in designing a molecular communication system. The contribution of this dissertation is proposing well-justified models for signal propagation, noise sources, optimum receiver design and synchronization in molecular communication channels. The design of any communication system is primarily based on the signal propagation channel and noise models. Using the Brownian motion and advection molecular statistics, separate signal propagation and noise models are presented for diffusion-based and flow-based molecular communication channels. It is shown that the corrupting noise of molecular channels is uncorrelated and non-stationary with a signal dependent magnitude. The next key component of any communication system is the reception and detection process. This dissertation provides a detailed analysis of the effect of the ligand-receptor binding mechanism on the received signal, and develops the first optimal receiver design for molecular communications. The bit error rate performance of the proposed receiver is evaluated and the impact of medium motion on the receiver performance is investigated. Another important feature of any communication system is synchronization. In this dissertation, the first blind synchronization algorithm is presented for the molecular communication channels. The proposed algorithm uses a non-decision directed maximum likelihood criterion for estimating the channel delay. The Cramer-Rao lower bound is also derived and the performance of the proposed synchronization algorithm is evaluated by investigating its mean square error.

Apparatus for plasma surface treating and preparation of membrane layers

NARCIS (Netherlands)

1990-01-01

An apparatus suitable for plasma surface treating (e.g., forming a membrane layer on a substrate surface) comprises a plasma generation section which is operable at least at substantially atmospheric pressure and is in communication via at least one plasma inlet (e.g., a nozzle) with an enclosed

Enhancing GRASS data communication with videographic technology

Energy Technology Data Exchange (ETDEWEB)

Sullivan, R.G. [Argonne National Lab., IL (United States); Gerdes, D.; Youngs, D. [Army Construction Engineering Research Lab., Champaign, IL (United States)

1992-07-01

Research at Argonne National Laboratory and the US Army Construction Engineering Research Laboratory has shown that computer videographic technology can be used to assist visualization and communication of GIS-generated geographic information. Videographic tools can be used to make results of GRASS analyses clear to decision-makers and to public interest groups, as well as to help GRASS users visualize geographic data more easily. Useful videographic visualization tools include graphic overlay of GRASS layers onto panchromatic images, allowing landscape features to be associated with GIS classifications; draping of GIS layers onto terrain models to create shaded relief maps; and incorporation of photographic imagery into GIS graphics. Useful videographic communications capabilities include convenient, direct interface to video formats, allowing incorporation of live video into GRASS graphics and output of GRASS graphics to video; convenient output of high-quality slides and prints; and enhanced labeling and editing of GRASS images. Conversion of GRASS imagery to standard videographic file formats also facilitates incorporation of GRASS images into other software programs, such as database and work-processing packages.

Enhancing GRASS data communication with videographic technology

Energy Technology Data Exchange (ETDEWEB)

Sullivan, R.G. (Argonne National Lab., IL (United States)); Gerdes, D.; Youngs, D. (Army Construction Engineering Research Lab., Champaign, IL (United States))

1992-01-01

Research at Argonne National Laboratory and the US Army Construction Engineering Research Laboratory has shown that computer videographic technology can be used to assist visualization and communication of GIS-generated geographic information. Videographic tools can be used to make results of GRASS analyses clear to decision-makers and to public interest groups, as well as to help GRASS users visualize geographic data more easily. Useful videographic visualization tools include graphic overlay of GRASS layers onto panchromatic images, allowing landscape features to be associated with GIS classifications; draping of GIS layers onto terrain models to create shaded relief maps; and incorporation of photographic imagery into GIS graphics. Useful videographic communications capabilities include convenient, direct interface to video formats, allowing incorporation of live video into GRASS graphics and output of GRASS graphics to video; convenient output of high-quality slides and prints; and enhanced labeling and editing of GRASS images. Conversion of GRASS imagery to standard videographic file formats also facilitates incorporation of GRASS images into other software programs, such as database and work-processing packages.

Magneto-Inductive Underground Communications in a District Heating System

DEFF Research Database (Denmark)

Meybodi, Soroush Afkhami; Nielsen, Jens Frederik Dalsgaard; Bendtsen, Jan Dimon

2011-01-01

Feasibility of underground data communications is investigated by employing magnetic induction as the key technology at physical layer. Realizing an underground wireless sensor network for a district heating plant motivates this research problem. The main contribution of the paper is to find the ...

Cross-Layer Design for Energy-Efficient Secure Multicast Communications in Ad Hoc Networks

National Research Council Canada - National Science Library

Lazos, Loukas; Poovendran, Radha

2004-01-01

.... They present an analytical formulation of the energy expenditure associated with the communication overhead of key management, and highlight its dependence on network topology and key distribution method...

Research and implementation of intelligent gateway driver layer based on Linux bus

Directory of Open Access Journals (Sweden)

ZHANG Jian

2016-10-01

Full Text Available Currently,in the field of smart home,there is no relevant organization that yet has proposed an unified protocol standard.It increases the complexity and limitations of heterogeneous gateway software framework design that different vendor′s devices have different communication mode and protocol standards.In this paper,a serial of interfaces are provided by Linux kernel,and a virtual bus is registered under Linux.The physical device drivers are able to connect to the virtual bus.The detailed designs of the communication protocol are placed in the underlying adapters,making the integration of heterogeneous networks more natural.At the same time,designing the intelligent gateway system driver layer based on Linux bus can let the application layer be more unified and clear logical.And it also let the hardware access network become more convenient and distinct.

Multilayered security and privacy protection in Car-to-X networks solutions from application down to physical layer

CERN Document Server

Stübing, Hagen

2013-01-01

Car-to-X (C2X) communication in terms of Car-to-Car (C2C) and Car-to-Infrastructure (C2I) communication aims at increasing road safety and traffic efficiency by exchanging foresighted traffic information. Thereby, security and privacy are regarded as an absolute prerequisite for successfully establishing the C2X technology on the market. Towards the paramount objective of covering the entire ITS reference model with security and privacy measures, Hagen Stübing develops dedicated solutions for each layer, respectively. On application layer a security architecture in terms of a Public Key Infras

SystemC modelling of wireless communication channel

Science.gov (United States)

Conti, Massimo; Orcioni, Simone

2011-05-01

This paper presents the definition in SystemC of wireless channels at different levels of abstraction. The different levels of description of the wireless channel can be easily interchanged allowing the reuse of the application and baseband layers in a high level analysis of the network or in a deep analysis of the communication between the wireless devices.

Method for plasma surface treating and preparation of membrane layers

NARCIS (Netherlands)

1992-01-01

The invention relates to an apparatus suitable for plasma surface treating (e.g. forming a membrane layer on a substrate) which comprises a plasma generation section (2) which is in communication via at least one plasma inlet means (4) (e.g. a nozzle) with an enclosed plasma treating section (3)

Cooperating systems: Layered MAS

Science.gov (United States)

Rochowiak, Daniel

1990-01-01

Distributed intelligent systems can be distinguished by the models that they use. The model developed focuses on layered multiagent system conceived of as a bureaucracy in which a distributed data base serves as a central means of communication. The various generic bureaus of such a system is described and a basic vocabulary for such systems is presented. In presenting the bureaus and vocabularies, special attention is given to the sorts of reasonings that are appropriate. A bureaucratic model has a hierarchy of master system and work group that organizes E agents and B agents. The master system provides the administrative services and support facilities for the work groups.

Physical and data-link security techniques for future communication systems

CERN Document Server

Tomasin, Stefano

2016-01-01

 This book focuses on techniques that can be applied at the physical and data-link layers of communication systems in order to secure transmissions against eavesdroppers. Topics ranging from information theory-based security to coding for security and cryptography are discussed, with presentation of cutting-edge research and innovative results from leading researchers. The characteristic feature of all the contributions is their relevance for practical embodiments: detailed consideration is given to applications of security principles to a variety of widely used communication techniques such as multiantenna systems, ultra-wide band communication systems, power line communications, and quantum key distribution techniques. A further distinctive aspect is the attention paid to both unconditional and computational security techniques, providing a bridge between two usually distinct worlds. The book comprises extended versions of contributions delivered at the Workshop on Communication Security, held in Ancona, I...

Relevance, Realization and stability of a cold layer at the plasma edge for fusion reactors

International Nuclear Information System (INIS)

1990-09-01

The workshop was dedicated to the realization and stability of a cold layer at the plasma edge for fusion reactors. The subjects of the communications presented were: impurity transport, and control, plasma boundary layers, power balance, radiation control and modifications, limiter discharges, tokamak density limit, Asdex divertor discharges, thermal stability of a radiating diverted plasma, plasma stability, auxiliary heating in Textor, detached plasma in Tore Supra, poloidal divertor tokamak, radiation cooling, neutral-particle transport, plasma scrape-off layer, edge turbulence

Voice Communications over 802.11 Ad Hoc Networks: Modeling, Optimization and Call Admission Control

Science.gov (United States)

Xu, Changchun; Xu, Yanyi; Liu, Gan; Liu, Kezhong

Supporting quality-of-service (QoS) of multimedia communications over IEEE 802.11 based ad hoc networks is a challenging task. This paper develops a simple 3-D Markov chain model for queuing analysis of IEEE 802.11 MAC layer. The model is applied for performance analysis of voice communications over IEEE 802.11 single-hop ad hoc networks. By using the model, we finish the performance optimization of IEEE MAC layer and obtain the maximum number of voice calls in IEEE 802.11 ad hoc networks as well as the statistical performance bounds. Furthermore, we design a fully distributed call admission control (CAC) algorithm which can provide strict statistical QoS guarantee for voice communications over IEEE 802.11 ad hoc networks. Extensive simulations indicate the accuracy of the analytical model and the CAC scheme.

A proposed architecture for a satellite-based mobile communications network - The lowest three layers

Science.gov (United States)

Yan, T. Y.; Naderi, F. M.

1986-01-01

Architecture for a commercial mobile satellite network is proposed. The mobile satellite system (MSS) is composed of a network management center, mobile terminals, base stations, and gateways; the functions of each component are described. The satellite is a 'bent pipe' that performs frequency translations, and it has multiple UHF beams. The development of the MSS design based on the seven-layer open system interconnection model is examined. Consideration is given to the functions of the physical, data link, and network layers and the integrated adaptive mobile access protocol.

Insights into the European Years’ Communication Toolboxes

Directory of Open Access Journals (Sweden)

Camelia-Mihaela Cmeciu

2012-08-01

Full Text Available Since 1983 the European syntagm “unity in diversity” has been implemented in the European Years’ communication campaigns. Dependent on subsidiarity and decentralization, European Years focus on a specific issue which constitutes the subject of a year-long awareness campaign. Beyond the involvement of Europe’s citizens through their local, regional and national authorities in the implementation of the European Years’ policies, there is a unity at the level of the visual communication of the EU by two important image-building elements: EY logos and communication toolboxes. The European Years’ communication toolboxes can be considered signs of inclusion since every organization is expected to customize the templates in the official campaign design of the European Year. The analysis will focus on the image-building elements of three European Years (2010, 2011, 2012. Having social semiotics as the qualitative research method and the analytical framework based on the distinction between design resources and representational resources, I will analyze the double layers of the high intensity point of inclusion: (1 the European Years’ branding process; (2 the visual deontic modality within the visual guidelines of the EY communication toolbox.

Linguistic layers of Old Hungarian hydronyms

OpenAIRE

Győrffy, Erzsébet

2014-01-01

When analysing the etymological layers of Hungarian river names, it becomes soon clear that loan names make up a much larger group than in the group of settlement names, for instance. This fact can be due to the phenomenon that in the case of hydronyms, name-giving and name-usage is driven mainly by communicative needs, while other (e. g. socio-cultural or political) factors only rarely influence name-giving. In my paper, it was my aim to provide an etymological typology of Hungarian hydronym...

Clustering Approaches for Pragmatic Two-Layer IoT Architecture

Directory of Open Access Journals (Sweden)

J. Sathish Kumar

2018-01-01

Full Text Available Connecting all devices through Internet is now practical due to Internet of Things. IoT assures numerous applications in everyday life of common people, government bodies, business, and society as a whole. Collaboration among the devices in IoT to bring various applications in the real world is a challenging task. In this context, we introduce an application-based two-layer architectural framework for IoT which consists of sensing layer and IoT layer. For any real-time application, sensing devices play an important role. Both these layers are required for accomplishing IoT-based applications. The success of any IoT-based application relies on efficient communication and utilization of the devices and data acquired by the devices at both layers. The grouping of these devices helps to achieve the same, which leads to formation of cluster of devices at various levels. The clustering helps not only in collaboration but also in prolonging overall network lifetime. In this paper, we propose two clustering algorithms based on heuristic and graph, respectively. The proposed clustering approaches are evaluated on IoT platform using standard parameters and compared with different approaches reported in literature.

Speech and language therapists' views about AAC system acceptance by people with acquired communication disorders.

Science.gov (United States)

Pampoulou, Eliada

2018-04-18

Some adults with acquired communication disorders are faced with an inability to communicate coherently through verbal speech with their communication partners. Despite the fact that a variety of augmentative and alternative communication (AAC) aided systems is available to assist them in communicating, not all adults accept them. In Cyprus, there is scant research focusing on the factors that are linked to AAC system acceptance and abandonment. To address this gap, this research involves exploring the experiences of six speech and language therapists supporting adults with acquired communication disorders, who could benefit from the use of AAC systems. The main research question is: What are the factors that influence AAC system acceptance or abandonment? The method used for data collection, was semi-structured interviews and the transcripts were analyzed thematically. The findings show that a number of factors influence the acceptance of AAC systems. These include the time since onset and acceptance of disability, the person's attitude towards communication facilitators, and the perceptions about AAC systems. These findings indicate that the process of accepting an AAC system is multi-layered and these layers are interrelated. More research is warranted focusing directly on the experiences of people with acquired communication disorders and their communication partners. Implications for Rehabilitation The different myths about AAC systems need to be challenged such that awareness about their usefulness is raised. AAC specialists need to find ways to spread the message that AAC systems can actually support language, speech and communication through different dissemination avenues, such as articles in newspapers and talks through the media.

On Medium Chemical Reaction in Diffusion-Based Molecular Communication: a Two-Way Relaying Example

OpenAIRE

Farahnak-Ghazani, Maryam; Aminian, Gholamali; Mirmohseni, Mahtab; Gohari, Amin; Nasiri-Kenari, Masoumeh

2016-01-01

Chemical reactions are a prominent feature of molecular communication (MC) systems, with no direct parallels in wireless communications. While chemical reactions may be used inside the transmitter nodes, receiver nodes or the communication medium, we focus on its utility in the medium in this paper. Such chemical reactions can be used to perform computation over the medium as molecules diffuse and react with each other (physical-layer computation). We propose the use of chemical reactions for...

107th meeting of the working group electronic instrumentation in Spring 2016; 107. Tagung der Studiengruppe elektronische Instrumentierung im Fruehjahr 2016

Energy Technology Data Exchange (ETDEWEB)

Goettlicher, Peter (ed.)

2016-06-15

The following topics were dealt with: Instrumentation and the NUSTAR physics program in FAIR phase-0, actual projects of the group EE-digital electronics, ethernet-based data acquisition beyond 10 GBit/s, the big data problem in DAQ systems, a general front-end readout architecture in scientific detector systems, the KALYPSO detection system for single-shot electro-optical bunch measurements, MicroTCA based RF and laser cavity regulation including piezo controls, FPGA implementation for data acquisition system with gigabit serial link and PCIe interface, next generation MTCA.4 crate, increased PCIexpress band-width up to 128 Gb/s and optical PCIexpress cascading, power supplies for the sensitive measurement techniques and the complex automatization, error-save industry PC, the interfacing of NI products to EPICS, Green Cube, a survey of EPICS rate at GSI and FAIR, CS++ as actor-based successor of the CS framework, synchronized fast shutter control with adaptive phase shift compensation in the EtherCAT motion control system, precise voltage supply for the SiPM of a Cherenkov telescope in the Antarctis, development of a multichannel readout hardware for delay-line neutron detectors, silicon photonic data transmission for detector instrumentation, EMV consideration of the Maria instrument at the FRM2, quench detectors for FAIR, optimized illumination and in-situ calibration of high-gain antennas for the detection of extensive cosmic air showers. (HSI)

107th meeting of the working group electronic instrumentation in Spring 2016

International Nuclear Information System (INIS)

Goettlicher, Peter

2016-06-01

The following topics were dealt with: Instrumentation and the NUSTAR physics program in FAIR phase-0, actual projects of the group EE-digital electronics, ethernet-based data acquisition beyond 10 GBit/s, the big data problem in DAQ systems, a general front-end readout architecture in scientific detector systems, the KALYPSO detection system for single-shot electro-optical bunch measurements, MicroTCA based RF and laser cavity regulation including piezo controls, FPGA implementation for data acquisition system with gigabit serial link and PCIe interface, next generation MTCA.4 crate, increased PCIexpress band-width up to 128 Gb/s and optical PCIexpress cascading, power supplies for the sensitive measurement techniques and the complex automatization, error-save industry PC, the interfacing of NI products to EPICS, Green Cube, a survey of EPICS rate at GSI and FAIR, CS++ as actor-based successor of the CS framework, synchronized fast shutter control with adaptive phase shift compensation in the EtherCAT motion control system, precise voltage supply for the SiPM of a Cherenkov telescope in the Antarctis, development of a multichannel readout hardware for delay-line neutron detectors, silicon photonic data transmission for detector instrumentation, EMV consideration of the Maria instrument at the FRM2, quench detectors for FAIR, optimized illumination and in-situ calibration of high-gain antennas for the detection of extensive cosmic air showers. (HSI)

Research on radiation characteristics of dipole antenna modulation by sub-wavelength inhomogeneous plasma layer

Directory of Open Access Journals (Sweden)

Fanrong Kong

2018-02-01

Full Text Available The modulation and enhancement effect of sub-wavelength plasma structures on compact antennas exhibits obvious technological advantage and considerable progress. In order to extend the availability of this technology under complex and actual environment with inhomogeneous plasma structure, a numerical simulation analysis based on finite element method has been conducted in this paper. The modulation function of the antenna radiation with sub-wavelength plasma layer located at different positions was investigated, and the inhomogeneous plasma layer with multiple electron density distribution profiles were employed to explore the effect of plasma density distribution on the antenna radiation. It has been revealed that the optical near-field modulated distance and reduced plasma distribution are more beneficial to enhance the radiation. On the basis above, an application-focused research about communication through the plasma sheath surrounding a hypersonic vehicle has been carried out aiming at exploring an effective communication window. The relevant results devote guiding significance in the field of antenna radiation modulation and enhancement, as well as the development of communication technology in hypersonic flight.

Research on radiation characteristics of dipole antenna modulation by sub-wavelength inhomogeneous plasma layer

Science.gov (United States)

Kong, Fanrong; Chen, Peiqi; Nie, Qiuyue; Zhang, Xiaoning; Zhang, Zhen; Jiang, Binhao

2018-02-01

The modulation and enhancement effect of sub-wavelength plasma structures on compact antennas exhibits obvious technological advantage and considerable progress. In order to extend the availability of this technology under complex and actual environment with inhomogeneous plasma structure, a numerical simulation analysis based on finite element method has been conducted in this paper. The modulation function of the antenna radiation with sub-wavelength plasma layer located at different positions was investigated, and the inhomogeneous plasma layer with multiple electron density distribution profiles were employed to explore the effect of plasma density distribution on the antenna radiation. It has been revealed that the optical near-field modulated distance and reduced plasma distribution are more beneficial to enhance the radiation. On the basis above, an application-focused research about communication through the plasma sheath surrounding a hypersonic vehicle has been carried out aiming at exploring an effective communication window. The relevant results devote guiding significance in the field of antenna radiation modulation and enhancement, as well as the development of communication technology in hypersonic flight.

Past Results, Present Trends, and Future Challenges in Intrabody Communication

Directory of Open Access Journals (Sweden)

David Naranjo-Hernández

2018-01-01

Full Text Available Intrabody communication (IBC is a wireless communication technology using the human body to develop body area networks (BANs for remote and ubiquitous monitoring. IBC uses living tissues as a transmission medium, achieving power-saving and miniaturized transceivers, making communications more robust against external interference and attacks on the privacy of transmitted data. Due to these advantages, IBC has been included as a third physical layer in the IEEE 802.15.6 standard for wireless body area networks (WBANs designated as Human Body Communication (HBC. Further research is needed to compare both methods depending on the characteristics of IBC application. Challenges remain for an optimal deployment of IBC technology, such as the effect of long-term use in the human body, communication optimization through more realistic models, the influence of both anthropometric characteristics and the subject’s movement on the transmission performance, standardization of communications, and development of small-size and energy-efficient prototypes with increased data rate. The purpose of this work is to provide an in-depth overview of recent advances and future challenges in human body/intrabody communication for wireless communications and mobile computing.

Principles of Mobile Communication

CERN Document Server

Stüber, Gordon L

2012-01-01

This mathematically rigorous overview of physical layer wireless communications is now in a third, fully revised and updated edition. Along with coverage of basic principles sufficient for novice students, the volume includes plenty of finer details that will satisfy the requirements of graduate students aiming to research the topic in depth. It also has a role as a handy reference for wireless engineers. The content stresses core principles that are applicable to a broad range of wireless standards. Beginning with a survey of the field that introduces an array of issues relevant to wireless communications and which traces the historical development of today’s accepted wireless standards, the book moves on to cover all the relevant discrete subjects, from radio propagation to error probability performance and cellular radio resource management. A valuable appendix provides a succinct and focused tutorial on probability and random processes, concepts widely used throughout the book. This new edition, revised...

Principles of mobile communication

CERN Document Server

Stüber, Gordon L

2017-01-01

This mathematically rigorous overview of physical layer wireless communications is now in a 4th, fully revised and updated edition. The new edition features new content on 4G cellular systems, 5G cellular outlook, bandpass signals and systems, and polarization, among many other topics, in addition to a new chapters on channel assignment techniques. Along with coverage of fundamentals and basic principles sufficient for novice students, the volume includes finer details that satisfy the requirements of graduate students aiming to conduct in-depth research. The book begins with a survey of the field, introducing issues relevant to wireless communications. The book moves on to cover relevant discrete subjects, from radio propagation, to error probability performance, and cellular radio resource management. An appendix provides a tutorial on probability and random processes. The content stresses core principles that are applicable to a broad range of wireless standards. New examples are provided throughout the bo...

Magneto-Inductive Communication among Pumps in a District Heating System

DEFF Research Database (Denmark)

Afkhami Meybodi, Soroush; Pardo, Pablo; Dohler, Mischa

2011-01-01

Realizing distributed control for a large scale district heating plant needs a metropolitan wireless communication framework among its pumps. The main challenge at PHY layer here is coverage rather than interference. This paper reviews the potential methods and proposes the use of magnetic induct...

The Study on the Communication Network of Wide Area Measurement System in Electricity Grid

Science.gov (United States)

Xiaorong, Cheng; Ying, Wang; Yangdan, Ni

Wide area measurement system(WAMS) is a fundamental part of security defense in Smart Grid, and the communication system of WAMS is an important part of Electric power communication network. For a large regional network is concerned, the real-time data which is transferred in the communication network of WAMS will affect the safe operation of the power grid directly. Therefore, WAMS raised higher requirements for real-time, reliability and security to its communication network. In this paper, the architecture of WASM communication network was studied according to the seven layers model of the open systems interconnection(OSI), and the network architecture was researched from all levels. We explored the media of WAMS communication network, the network communication protocol and network technology. Finally, the delay of the network were analyzed.

Layered virus protection for the operations and administrative messaging system

Science.gov (United States)

Cortez, R. H.

2002-01-01

NASA's Deep Space Network (DSN) is critical in supporting the wide variety of operating and plannedunmanned flight projects. For day-to-day operations it relies on email communication between the three Deep Space Communication Complexes (Canberra, Goldstone, Madrid) and NASA's Jet Propulsion Laboratory. The Operations & Administrative Messaging system, based on the Microsoft Windows NTand Exchange platform, provides the infrastructure that is required for reliable, mission-critical messaging. The reliability of this system, however, is threatened by the proliferation of email viruses that continue to spread at alarming rates. A layered approach to email security has been implemented across the DSN to protect against this threat.

A Pattern Construction Scheme for Neural Network-Based Cognitive Communication

Directory of Open Access Journals (Sweden)

Ozgur Orcay

2011-01-01

Full Text Available Inefficient utilization of the frequency spectrum due to conventional regulatory limitations and physical performance limiting factors, mainly the Signal to Noise Ratio (SNR, are prominent restrictions in digital wireless communication. Pattern Based Communication System (PBCS is an adaptive and perceptual communication method based on a Cognitive Radio (CR approach. It intends an SNR oriented cognition mechanism in the physical layer for improvement of Link Spectral Efficiency (LSE. The key to this system is construction of optimal communication signals, which consist of encoded data in different pattern forms (waveforms depending on spectral availabilities. The signals distorted in the communication medium are recovered according to the pre-trained pattern glossary by the perceptual receiver. In this study, we have shown that it is possible to improve the bandwidth efficiency when largely uncorrelated signal patterns are chosen in order to form a glossary that represents symbols for different length data groups and the information can be recovered by the Artificial Neural Network (ANN in the receiver site.

A TCP/IP transport layer for the DAQ of the CMS experiment

International Nuclear Information System (INIS)

Kozlovszky, M.

2004-01-01

The CMS collaboration is currently investigating various networking technologies that may meet the requirements of the CMS Data Acquisition System (DAQ). During this study, a peer transport component based on TCP/IP has been developed using object-oriented techniques for the distributed DAQ framework named XDAQ. This framework has been designed to facilitate the development of distributed data acquisition systems within the CMS Experiment. The peer transport component has to meet 3 main requirements. Firstly, it had to provide fair access to the communication medium for competing applications. Secondly, it had to provide as much of the available bandwidth to the application layer as possible. Finally, it had to hide the complexity of using non-blocking TCP/IP connections from the application layer. This paper describes the development of the peer transport component and then presents and draws conclusions on the measurements made during tests. The major topics investigated include: blocking versus non-blocking communication, TCP/IP configuration options, multi-rail connections

Physical layer impairments tolerance based lightpath provision in software defined optical network

Institute of Scientific and Technical Information of China (English)

Zhao Xianlong; Xu Xianze; Bai Huifeng

2017-01-01

As all-optical networks grow with ever increasing ultra-high speed, the communication quality suffers seriously from physical layer impairments ( PLIs) .The same problem still exists in software defined optical network ( SDON) controlled by OpenFlow.Aimed to solve this problem, a PLIs tol-erance based lightpath provision scheme is proposed for OpenFlow controlled optical networks.This proposed approach not only takes the OSNR model to represent those linear PLIs factors, but also in-troduces those nonlinear factors into the OSNR model.Thus, the proposed scheme is able to cover most PLIs factors of each optical link and conduct optical lightpath provison with better communica-tion quality.Moreover, PLIs tolerance model is also set up and considered in this work with some necessary extension to OpenFlow protocols to achieve better compatibility between physical layer im-pairments factors and various services connections.Simulation results show that the proposed scheme is able to get better performance in terms of packet loss rate and connection setup time.

Intercultural Communication Ethics and Communication Competence%Intercultural Communication Ethics and Communication Competence

Institute of Scientific and Technical Information of China (English)

时婷洁

2012-01-01

This paper investigates intercultural communication ethics is a vital element to promote intercultural communication competence. Firstly, it defines the concept of intercultural communication ethics; Secondly, it illustrates the relation between ethics and the key point of intercultural communication competence; and finally addresses how intercultural communication ethics can improve intercultural communication competence.

Real-time communication for distributed plasma control systems

Energy Technology Data Exchange (ETDEWEB)

Luchetta, A. [Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Corso Stati Uniti 4, Padova 35127 (Italy)], E-mail: adriano.luchetta@igi.cnr.it; Barbalace, A.; Manduchi, G.; Soppelsa, A.; Taliercio, C. [Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Corso Stati Uniti 4, Padova 35127 (Italy)

2008-04-15

Real-time control applications will benefit in the near future from the enhanced performance provided by multi-core processor architectures. Nevertheless real-time communication will continue to be critical in distributed plasma control systems where the plant under control typically is distributed over a wide area. At RFX-mod real-time communication is crucial for hard real-time plasma control, due to the distributed architecture of the system, which consists of several VMEbus stations. The system runs under VxWorks and uses Gigabit Ethernet for sub-millisecond real-time communication. To optimize communication in the system, a set of detailed measurements has been carried out on the target platforms (Motorola MVME5100 and MVME5500) using either the VxWorks User Datagram Protocol (UDP) stack or raw communication based on the data link layer. Measurements have been carried out also under Linux, using its UDP stack or, in alternative, RTnet, an open source hard real-time network protocol stack. RTnet runs under Xenomai or RTAI, two popular real-time extensions based on the Linux kernel. The paper reports on the measurements carried out and compares the results, showing that the performance obtained by using open source code is suitable for sub-millisecond real-time communication in plasma control.

Method of Performance-Aware Security of Unicast Communication in Hybrid Satellite Networks

Science.gov (United States)

Roy-Chowdhury, Ayan (Inventor); Baras, John S. (Inventor)

2014-01-01

A method and apparatus utilizes Layered IPSEC (LES) protocol as an alternative to IPSEC for network-layer security including a modification to the Internet Key Exchange protocol. For application-level security of web browsing with acceptable end-to-end delay, the Dual-mode SSL protocol (DSSL) is used instead of SSL. The LES and DSSL protocols achieve desired end-to-end communication security while allowing the TCP and HTTP proxy servers to function correctly.

Social-Aware Relay Selection for Cooperative Multicast Device-to-Device Communications

Directory of Open Access Journals (Sweden)

Francesco Chiti

2017-12-01

Full Text Available The increasing use of social networks such as Facebook, Twitter, and Instagram to share photos, video streaming, and music among friends has generated a huge increase in the amount of data traffic over wireless networks. This social behavior has triggered new communication paradigms such as device-to-device (D2D and relaying communication schemes, which are both considered as strong drivers for the next fifth-generation (5G cellular systems. Recently, the social-aware layer and its relationship to and influence on the physical communications layer have gained great attention as emerging focus points. We focus here on the case of relaying communications to pursue the multicast data dissemination to a group of users forming a social community through a relay node, according to the extension of the D2D mode to the case of device-to-many devices. Moreover, in our case, the source selects the device to act as the relay among different users of the multicast group by taking into account both the propagation link conditions and the relay social-trust level with the constraint of minimizing the end-to-end content delivery delay. An optimization procedure is also proposed in order to achieve the best performance. Finally, numerical results are provided to highlight the advantages of considering the impact of social level on the end-to-end delivery delay in the integrated social–physical network in comparison with the classical relay-assisted multicast communications for which the relay social-trust level is not considered.

Cross-layer combining of information-guided transmission withnetwork coding relaying for multiuser cognitive radio systems

KAUST Repository

Yang, Yuli

2013-02-01

For a cognitive radio relaying network, we propose a cross-layer design by combining information-guided transmission at the physical layer and network coding at the network layer. With this design, a common relay is exploited to help the communications between multiple secondary source-destination pairs, which allows for a more efficient use of the radio resources, and moreover, generates less interference to primary licensees in the network. Considering the spectrum-sharing constraints on the relay and secondary sources, the achievable data rate of the proposed cross-layer design is derived and evaluated. Numerical results on average capacity and uniform capacity in the network under study substantiate the efficiency of our proposed design. © 2013 IEEE.

Unified compression and encryption algorithm for fast and secure network communications

International Nuclear Information System (INIS)

Rizvi, S.M.J.; Hussain, M.; Qaiser, N.

2005-01-01

Compression and encryption of data are two vital requirements for the fast and secure transmission of data in the network based communications. In this paper an algorithm is presented based on adaptive Huffman encoding for unified compression and encryption of Unicode encoded textual data. The Huffman encoding weakness that same tree is needed for decoding is utilized in the algorithm presented as an extra layer of security, which is updated whenever the frequency change is above the specified threshold level. The results show that we get compression comparable to popular zip format and in addition to that data has got an additional layer of encryption that makes it more secure. Thus unified algorithm presented here can be used for network communications between different branches of banks, e- Government programs and national database and registration centers where data transmission requires both compression and encryption. (author)

Development and Evaluation of Secure Socket Layer Visualization Tool with Packet Capturing Function

Directory of Open Access Journals (Sweden)

Arai Masayuki

2015-01-01

Full Text Available Secure Socket Layer (SSL has become a fundamental technology that secures browser-processed personal details sent to the server. As a result, communication and computer engineers are advised to learn the protocol. However, understanding SSL is very difficult because of its intricate communication procedure. To solve this problem, we developed a visualization tool for understanding SSL. This paper describes the design, implementation methods, and evaluation of the tool. The evaluation results show that the visualization tool is effective for learning SSL.

Digital enclosure and the communication commons revival

OpenAIRE

Anderson, Stephen Edward

2008-01-01

This thesis considers the political and economic forces shaping the Internet as a medium of increasing importance in everyday life. The digital communications infrastructure is currently facing commercial enclosure on three layers: physical (regulation and ownership of the wires), content (copyright policies, media technology, ownership), and space (ownership and orientation of online tools, spaces, and services). This thesis explores and analyzes the power dynamics driving enclosure on each ...

An Embedded System Dedicated to Intervehicle Communication Applications

Directory of Open Access Journals (Sweden)

Zhou Haiying

2010-01-01

Full Text Available To overcome system latency and network delay is essential for intervehicle communication (IVC applications such as hazard alarming and cooperative driving. This paper proposes a low-cost embedded software system dedicated to such applications. It consists of two basic component layers: an operating system, named HEROS (hybrid event-driven and real-time multitasking operating system, and a communication protocol, named CIVIC (Communication Inter Véhicule Intelligente et Coopérative. HEROS is originally designed for wireless sensor networks (WSNs. It contains a component-based resource-aware kernel and a low-latency tuple-based communication system. Moreover, it provides a configurable event-driven and/or real-time multitasking mechanism for various embedded applications. The CIVIC is an autoconfiguration cooperative IVC protocol. It merges proactive and reactive approaches to speed up and optimize location-based routing discovery with high-mobility nodes. Currently, this embedded system has been implemented and tested. The experiment results show that the new embedded system has low system latency and network delay under the principle of small resource consumption.

Apparatus suitable for plasma surface treating and process for preparing membrane layers

NARCIS (Netherlands)

1988-01-01

The invention relates to an apparatus suitable for plasma surface treating (e.g. forming a membrane layer on a substrate) which comprises a plasma generation section (2) which is in communication via at least one plasma inlet means (4) (e.g. a nozzle) with an enclosed plasma treating section (3)

Network design consideration of a satellite-based mobile communications system

Science.gov (United States)

Yan, T.-Y.

1986-01-01

Technical considerations for the Mobile Satellite Experiment (MSAT-X), the ground segment testbed for the low-cost spectral efficient satellite-based mobile communications technologies being developed for the 1990's, are discussed. The Network Management Center contains a flexible resource sharing algorithm, the Demand Assigned Multiple Access scheme, which partitions the satellite transponder bandwidth among voice, data, and request channels. Satellite use of multiple UHF beams permits frequency reuse. The backhaul communications and the Telemetry, Tracking and Control traffic are provided through a single full-coverage SHF beam. Mobile Terminals communicate with the satellite using UHF. All communications including SHF-SHF between Base Stations and/or Gateways, are routed through the satellite. Because MSAT-X is an experimental network, higher level network protocols (which are service-specific) will be developed only to test the operation of the lowest three levels, the physical, data link, and network layers.

Rapid Development of System-on-Chip (SoC for Network-Enabled Visible Light Communications

Directory of Open Access Journals (Sweden)

Trio Adiono

2018-03-01

Full Text Available Visible Light Communication (VLC is an emerging optical communication technology with rapid development nowadays. VLC is considered as a compliment and successor of radio-frequency (RF wireless communication. There are various typical implementations of VLC in which one of them is for exchanging data TCP/IP packets, thus the user can browse the internet as in established Wireless fidelity (Wi-Fi technology. Briefly, we can call it by Light fidelity (Li-Fi. This paper described the design and implementation of System-on-Chip (SoC subsystem for Li-Fi application where the implemented SoC consists of hardware (H/W and software (S/W. In the H/W aspect, Physical Layer (PHY is made by using UART communication with Ethernet connection to communicate with Host/Device personal-computer (PC. In the S/W aspect, Xillinux operating system (OS is used. The H/W- as well as S/W-SoC, are realized in FPGA Zybo Zynq-7000 EPP development board. The functional test result shows (without optical channel or Zybo-to-Zybo only that the implemented SoC is working as expected. It is able to exchange TCP/IP packets between two PCs. Moreover, Ethernet connection has bandwidth up to 83.6 Mbps and PHY layer baud rate has bandwidth up to 921600 bps.

Combined peak-to-average power ratio reduction and physical layer security enhancement in optical orthogonal frequency division multiplexing visible-light communication systems

Science.gov (United States)

Wang, Zhongpeng; Chen, Shoufa

2016-07-01

A physical encryption scheme for discrete Hartley transform (DHT) precoded orthogonal frequency division multiplexing (OFDM) visible-light communication (VLC) systems using frequency domain chaos scrambling is proposed. In the scheme, the chaos scrambling, which is generated by a modified logistic mapping, is utilized to enhance the physical layer of security, and the DHT precoding is employed to reduce of OFDM signal for OFDM-based VLC. The influence of chaos scrambling on peak-to-average power ratio (PAPR) and bit error rate (BER) of systems is studied. The experimental simulation results prove the efficiency of the proposed encryption method for DHT-precoded, OFDM-based VLC systems. Furthermore, the influence of the proposed encryption to the PAPR and BER of systems is evaluated. The experimental results show that the proposed security scheme can protect the DHT-precoded, OFDM-based VLC from eavesdroppers, while keeping the good BER performance of DHT-precoded systems. The BER performance of the encrypted and DHT-precoded system is almost the same as that of the conventional DHT-precoded system without encryption.

Advanced information processing system: Inter-computer communication services

Science.gov (United States)

Burkhardt, Laura; Masotto, Tom; Sims, J. Terry; Whittredge, Roy; Alger, Linda S.

1991-01-01

The purpose is to document the functional requirements and detailed specifications for the Inter-Computer Communications Services (ICCS) of the Advanced Information Processing System (AIPS). An introductory section is provided to outline the overall architecture and functional requirements of the AIPS and to present an overview of the ICCS. An overview of the AIPS architecture as well as a brief description of the AIPS software is given. The guarantees of the ICCS are provided, and the ICCS is described as a seven-layered International Standards Organization (ISO) Model. The ICCS functional requirements, functional design, and detailed specifications as well as each layer of the ICCS are also described. A summary of results and suggestions for future work are presented.

A Review of Communications Protocol for Intelligent Remote Terminal Unit Development

Directory of Open Access Journals (Sweden)

Mohd Ruddin Ab. Ghani

2013-11-01

Full Text Available This paper reviewed all the possible interfacing communication protocols for remote terminal unit (RTU. Supervisory Control and Data Acquisition (SCADA system is a central station that can communicate with other network using the protocol. Fundamentally, the architectures of all networks are based on the seven layers of open system interconnection (OSI and International Standard Organization (ISO. The objective of designing the protocols is to check the status of all the input and output field devices and send the report according to that status. The corresponding protocol and communication parameters between the connecting devices will be included in designing a complex SCADA system. The available protocols to develop the communication of RTU are Modbus/ASCII, distributed network protocol (DNP3, controller area network (CAN, International Electro-technical Commission (IEC 60870, transmission control protocol/internet protocol (TCP/IP.

Utilizing Cross-Layer Information to Improve Performance in JPEG2000 Decoding

Directory of Open Access Journals (Sweden)

Hannes Persson

2007-01-01

Full Text Available We focus on wireless multimedia communication and investigate how cross-layer information can be used to improve performance at the application layer, using JPEG2000 as an example. The cross-layer information is in the form of soft information from the physical layer. The soft information, which is supplied by a soft decision demodulator, yields reliability measures for the received bits and is fed into two soft input iterative JPEG2000 image decoders. When errors are detected with the error detecting mechanisms in JPEG2000, the decoders utilize the soft information to point out likely transmission errors. Hence, the decoders can correct errors and increase the image quality without making time-consuming retransmissions. We believe that the proposed decoding method utilizing soft information is suitable for a general IP-based network and that it keeps the principles of a layered structure of the protocol stack intact. Further, experimental results with images transmitted over a simulated wireless channel show that a simple decoding algorithm that utilizes soft information can give high gains in image quality compared to the standard hard-decision decoding.

On the Security of Millimeter Wave Vehicular Communication Systems Using Random Antenna Subsets

KAUST Repository

Eltayeb, Mohammed E.

2017-03-20

Millimeter wave (mmWave) vehicular communication systems have the potential to improve traffic efficiency and safety. Lack of secure communication links, however, may lead to a formidable set of abuses and attacks. To secure communication links, a physical layer precoding technique for mmWave vehicular communication systems is proposed in this paper. The proposed technique exploits the large dimensional antenna arrays available at mmWave systems to produce direction dependent transmission. This results in coherent transmission to the legitimate receiver and artificial noise that jams eavesdroppers with sensitive receivers. Theoretical and numerical results demonstrate the validity and effectiveness of the proposed technique and show that the proposed technique provides high secrecy throughput when compared to conventional array and switched array transmission techniques.

On the Security of Millimeter Wave Vehicular Communication Systems Using Random Antenna Subsets

KAUST Repository

Eltayeb, Mohammed E.; Choi, Junil; Al-Naffouri, Tareq Y.; Heath, Robert W.

2017-01-01

Millimeter wave (mmWave) vehicular communication systems have the potential to improve traffic efficiency and safety. Lack of secure communication links, however, may lead to a formidable set of abuses and attacks. To secure communication links, a physical layer precoding technique for mmWave vehicular communication systems is proposed in this paper. The proposed technique exploits the large dimensional antenna arrays available at mmWave systems to produce direction dependent transmission. This results in coherent transmission to the legitimate receiver and artificial noise that jams eavesdroppers with sensitive receivers. Theoretical and numerical results demonstrate the validity and effectiveness of the proposed technique and show that the proposed technique provides high secrecy throughput when compared to conventional array and switched array transmission techniques.

QoS-aware self-adaptation of communication protocols in a pervasive service middleware

DEFF Research Database (Denmark)

Zhang, Weishan; Hansen, Klaus Marius; Fernandes, João

2010-01-01

Pervasive computing is characterized by heterogeneous devices that usually have scarce resources requiring optimized usage. These devices may use different communication protocols which can be switched at runtime. As different communication protocols have different quality of service (Qo......S) properties, this motivates optimized self-adaption of protocols for devices, e.g., considering power consumption and other QoS requirements, e.g. round trip time (RTT) for service invocations, throughput, and reliability. In this paper, we present an extensible approach for self-adaptation of communication...... protocols for pervasive web services, where protocols are designed as reusable connectors and our middleware infrastructure can hide the complexity of using different communication protocols to upper layers. We also propose to use Genetic Algorithms (GAs) to find optimized configurations at runtime...

A Hierarchical Communication Architecture for Oceanic Surveillance Applications

Science.gov (United States)

Macias, Elsa; Suarez, Alvaro; Chiti, Francesco; Sacco, Andrea; Fantacci, Romano

2011-01-01

The interest in monitoring applications using underwater sensor networks has been growing in recent years. The severe communication restrictions imposed by underwater channels make that efficient monitoring be a challenging task. Though a lot of research has been conducted on underwater sensor networks, there are only few concrete applications to a real-world case study. In this work, hence, we propose a general three tier architecture leveraging low cost wireless technologies for acoustic communications between underwater sensors and standard technologies, Zigbee and Wireless Fidelity (WiFi), for water surface communications. We have selected a suitable Medium Access Control (MAC) layer, after making a comparison with some common MAC protocols. Thus the performance of the overall system in terms of Signals Discarding Rate (SDR), signalling delay at the surface gateway as well as the percentage of true detection have been evaluated by simulation, pointing out good results which give evidence in applicability’s favour. PMID:22247669

Communication without communication

Directory of Open Access Journals (Sweden)

Bratina Boris R.

2017-01-01

Full Text Available This paper analyses the necessary conditions for successful communication. It is well known that post-modernity, described as an era of control, produces only decentralized, imploded subjectivities, who are neither able to question their own being nor to relate one with another in authentic bonds of communication. Today, virtual communication has become an ultimate model of every possible communication whatsoever. The authors, therefore, pose the question of conditions for possibility of subjectivities who would be able and apt for authentic communication, wherein faith, fidelity, truth, and capability of keeping one's word occupy the central place.

A packet switched communications system for GRO

Science.gov (United States)

Husain, Shabu; Yang, Wen-Hsing; Vadlamudi, Rani; Valenti, Joseph

1993-11-01

This paper describes the packet switched Instrumenters Communication System (ICS) that was developed for the Command Management Facility at GSFC to support the Gamma Ray Observatory (GRO) spacecraft. The GRO ICS serves as a vital science data acquisition link to the GRO scientists to initiate commands for their spacecraft instruments. The system is ready to send and receive messages at any time, 24 hours a day and seven days a week. The system is based on X.25 and the International Standard Organization's (ISO) 7-layer Open Systems Interconnection (OSI) protocol model and has client and server components. The components of the GRO ICS are discussed along with how the Communications Subsystem for Interconnection (CSFI) and Network Control Program Packet Switching Interface (NPSI) software are used in the system.

Upscaling of Two-Phase Immiscible Flows in Communicating Stratified Reservoirs

DEFF Research Database (Denmark)

Zhang, Xuan; Shapiro, Alexander; Stenby, Erling Halfdan

2011-01-01

A semi-analytical method for upscaling two-phase immiscible flows in heterogeneous porous media is described. This method is developed for stratified reservoirs with perfect communication between layers (the case of vertical equilibrium), in a viscous dominant regime, where the effects of capillary...... forces and gravity may be neglected. The method is discussed on the example of its basic application: waterflooding in petroleum reservoirs. We apply asymptotic analysis to a system of two-dimensional (2D) mass conservation equations for incompressible fluids. For high anisotropy ratios, the pressure...... and piston-like displacement, and it presumes non-zero exchange between layers. The method generalizes also the study of Yortsos (Transp Porous Media 18:107–129, 1995), taking into account in a more consistent way the interactions between the layers....

DICOM image secure communications with Internet protocols IPv6 and IPv4.

Science.gov (United States)

Zhang, Jianguo; Yu, Fenghai; Sun, Jianyong; Yang, Yuanyuan; Liang, Chenwen

2007-01-01

Image-data transmission from one site to another through public network is usually characterized in term of privacy, authenticity, and integrity. In this paper, we first describe a general scenario about how image is delivered from one site to another through a wide-area network (WAN) with security features of data privacy, integrity, and authenticity. Second, we give the common implementation method of the digital imaging and communication in medicine (DICOM) image communication software library with IPv6/IPv4 for high-speed broadband Internet by using open-source software. Third, we discuss two major security-transmission methods, the IP security (IPSec) and the secure-socket layer (SSL) or transport-layer security (TLS), being used currently in medical-image-data communication with privacy support. Fourth, we describe a test schema of multiple-modality DICOM-image communications through TCP/IPv4 and TCP/IPv6 with different security methods, different security algorithms, and operating systems, and evaluate the test results. We found that there are tradeoff factors between choosing the IPsec and the SSL/TLS-based security implementation of IPv6/IPv4 protocols. If the WAN networks only use IPv6 such as in high-speed broadband Internet, the choice is IPsec-based security. If the networks are IPv4 or the combination of IPv6 and IPv4, it is better to use SSL/TLS security. The Linux platform has more security algorithms implemented than the Windows (XP) platform, and can achieve better performance in most experiments of IPv6 and IPv4-based DICOM-image communications. In teleradiology or enterprise-PACS applications, the Linux operating system may be the better choice as peer security gateways for both the IPsec and the SSL/TLS-based secure DICOM communications cross public networks.

The Keck keyword layer

Science.gov (United States)

Conrad, A. R.; Lupton, W. F.

1992-01-01

Each Keck instrument presents a consistent software view to the user interface programmer. The view consists of a small library of functions, which are identical for all instruments, and a large set of keywords, that vary from instrument to instrument. All knowledge of the underlying task structure is hidden from the application programmer by the keyword layer. Image capture software uses the same function library to collect data for the image header. Because the image capture software and the instrument control software are built on top of the same keyword layer, a given observation can be 'replayed' by extracting keyword-value pairs from the image header and passing them back to the control system. The keyword layer features non-blocking as well as blocking I/O. A non-blocking keyword write operation (such as setting a filter position) specifies a callback to be invoked when the operation is complete. A non-blocking keyword read operation specifies a callback to be invoked whenever the keyword changes state. The keyword-callback style meshes well with the widget-callback style commonly used in X window programs. The first keyword library was built for the two Keck optical instruments. More recently, keyword libraries have been developed for the infrared instruments and for telescope control. Although the underlying mechanisms used for inter-process communication by each of these systems vary widely (Lick MUSIC, Sun RPC, and direct socket I/O, respectively), a basic user interface has been written that can be used with any of these systems. Since the keyword libraries are bound to user interface programs dynamically at run time, only a single set of user interface executables is needed. For example, the same program, 'xshow', can be used to display continuously the telescope's position, the time left in an instrument's exposure, or both values simultaneously. Less generic tools that operate on specific keywords, for example an X display that controls optical

Wireless Physical Layer Security with CSIT Uncertainty

KAUST Repository

Hyadi, Amal

2017-09-01

Recent years have been marked by an enormous growth of wireless communication networks and an extensive use of wireless applications. In return, this phenomenal expansion induced more concerns about the privacy and the security of the users. Physical layer security is one of the most promising solutions that were proposed to enhance the security of next generation wireless systems. The fundamental idea behind this technique is to exploit the randomness and the fluctuations of the wireless channel to achieve security without conditional assumptions on the computational capabilities of the eavesdropper. In fact, while these elements have traditionally been associated with signal deterioration, physical layer security uses them to ensure the confidentiality of the users. Nevertheless, these technical virtues rely heavily on perhaps idealistic channel state information assumptions. In that regard, the aim of this thesis is to look at the physical layer security paradigm from the channel uncertainty perspective. In particular, we discuss the ergodic secrecy capacity of different wiretap channels when the transmitter is hampered by the imperfect knowledge of the channel state information (CSI). We consider two prevalent causes of uncertainty for the CSI at transmitter (CSIT); either an error of estimation occurs at the transmitter and he can only base his coding and the transmission strategies on a noisy version of the CSI, or the CSI feedback link has a limited capacity and the legitimate receivers can only inform the transmitter about the quantized CSI. We investigate both the single-user multiple-input multiple-output (MIMO) wiretap channel and the multi-user broadcast wiretap channel. In the latter scenario, we distinguish between two situations: multiple messages transmission and common message transmission. We also discuss the broadcast channel with confidential messages (BCCM) where the transmitter has one common message to be transmitted to two users and one

Layering and Ordering in Electrochemical Double Layers

Energy Technology Data Exchange (ETDEWEB)

Liu, Yihua [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Kawaguchi, Tomoya [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Pierce, Michael S. [Rochester Institute of Technology, School of Physics and Astronomy, Rochester, New York 14623, United States; Komanicky, Vladimir [Faculty of Science, Safarik University, 041 54 Kosice, Slovakia; You, Hoydoo [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States

2018-02-26

Electrochemical double layers (EDL) form at electrified interfaces. While Gouy-Chapman model describes moderately charged EDL, formation of Stern layers was predicted for highly charged EDL. Our results provide structural evidence for a Stern layer of cations, at potentials close to hydrogen evolution in alkali fluoride and chloride electrolytes. Layering was observed by x-ray crystal truncation rods and atomic-scale recoil responses of Pt(111) surface layers. Ordering in the layer is confirmed by glancing-incidence in-plane diffraction measurements.

Remote Multi-layer Soil Temperature Monitoring System Based on GPRS

Directory of Open Access Journals (Sweden)

Ming Kuo CHEN

2014-02-01

Full Text Available There is the temperature difference between the upper and lower layer of the shallow soil in the forest. It is a potential energy that can be harvested by thermoelectric generator for the electronic device in the forest. The temperature distribution at different depths of the soil is the first step for thermoelectric generation. A remote multi-layer soil temperature monitoring system based on GPRS is proposed in this paper. The MSP430F149 MCU is used as the main controller of multi-layer soil temperature monitoring system. A temperature acquisition module is designed with DS18B20 and 4 core shielded twisted-pair cable. The GPRS module sends the measured data to remote server through wireless communication network. From the experiments in the campus of Beijing Forestry University, the maximum error of measured temperature in this system is 0.2°C by comparing with professional equipment in the same condition. The results of the experiments show that the system can accurately realize real-time monitoring of multi-layer soil temperature, and the data transmission is stable and reliable.

Photonics and other approaches to high speed communications

Science.gov (United States)

Maly, Kurt

1992-01-01

Our research group of 4 faculty and about 10-15 graduate students was actively involved (as a group) in the development of computer communication networks for the last five years. Many of its individuals have been involved in related research for a much longer period. The overall research goal is to extend network performance to higher data rates, to improve protocol performance at most ISO layers and to improve network operational performance. We briefly state our research goals, then discuss the research accomplishments and direct your attention to attached and/or published papers which cover the following topics: scalable parallel communications; high performance interconnection between high data rate networks; and a simple, effective media access protocol system for integrated, high data rate networks.

Acoustic explorations of the upper ocean boundary layer

Science.gov (United States)

Vagle, Svein

2005-04-01

The upper ocean boundary layer is an important but difficult to probe part of the ocean. A better understanding of small scale processes at the air-sea interface, including the vertical transfer of gases, heat, mass and momentum, are crucial to improving our understanding of the coupling between atmosphere and ocean. Also, this part of the ocean contains a significant part of the total biomass at all trophic levels and is therefore of great interest to researchers in a range of different fields. Innovative measurement plays a critical role in developing our understanding of the processes involved in the boundary layer, and the availability of low-cost, compact, digital signal processors and sonar technology in self-contained and cabled configurations has led to a number of exciting developments. This talk summarizes some recent explorations of this dynamic boundary layer using both active and passive acoustics. The resonant behavior of upper ocean bubbles combined with single and multi-frequency broad band active and passive devices are now giving us invaluable information on air-sea gas transfer, estimation of biological production, marine mammal behavior, wind speed and precipitation, surface and internal waves, turbulence, and acoustic communication in the surf zone.

All-optical signal processing data communication and storage applications

CERN Document Server

Eggleton, Benjamin

2015-01-01

This book provides a comprehensive review of the state-of-the art of optical signal processing technologies and devices. It presents breakthrough solutions for enabling a pervasive use of optics in data communication and signal storage applications. It presents presents optical signal processing as solution to overcome the capacity crunch in communication networks. The book content ranges from the development of innovative materials and devices, such as graphene and slow light structures, to the use of nonlinear optics for secure quantum information processing and overcoming the classical Shannon limit on channel capacity and microwave signal processing. Although it holds the promise for a substantial speed improvement, today’s communication infrastructure optics remains largely confined to the signal transport layer, as it lags behind electronics as far as signal processing is concerned. This situation will change in the near future as the tremendous growth of data traffic requires energy efficient and ful...

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

Directory of Open Access Journals (Sweden)

Yunchuan Guo

2014-01-01

Full Text Available 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.

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

Science.gov (United States)

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.

Kajian Aspek Security pada Jaringan Informasi dan Komunikasi Berbasis Visible Light Communication

Directory of Open Access Journals (Sweden)

Syifaul Fuada

2017-02-01

Full Text Available Cahaya tampak dapat dimanfaatkan sebagai media informasi ataupun komunikasi, teknologi ini dikenal dengan istilah Visible Light Communication yang menawarkan beberapa keunggulan dibandingkan komunikasi nirkabel lainnya seperti RF dan IR. Yakni cakupan bandwidth lebih lebar dan bebas lisensi, aman bagi kesehatan manusia dan tidak terganggu interferensi elektromagnetik. Sistem VLC terdiri atas tiga bagian besar, yakni bagian transmitter dengan menggunakan devais LED, kanal yang berupa ruang bebas (free space dan receiver dengan menggunakan devais photodetector atau image camera. Penerapan VLC berlandaskan pedoman IEEE 802.15.17 yang mana baru dirancang dalam waktu 5 tahun belakangani ini (sejak tahun 2009, meliputi meliputi layer fisik (physical layer dan layer MAC (medium access control.  Sebagaimana teknologi komunikasi pada umumnya, VLC juga menyediakan akses security yang dibahas pada bagian layer MAC. Namun pada praktiknya masih belum begitu masif dilakukan oleh para peneliti. Hal ini sangat wajar karena mengingat VLC merupakan teknologi yang sedang dalam tahap pengembangan yang menjadikan penelitian VLC umumnya berfokus pada ‘bagaimana meningkatkan speed dari keterbatasan komponen-komponen pembangun (IC, photodiode, LED, transistor, dll yang tersedia saat ini’. Tantangan teknologi VLC selain target peningkatan kecepatan bit-rate, mobility communication, mengurangi interference noise, menyediakan layanan multi-acces juga salah satunya adalah isu security. Makalah ini merupakan studi literature (review paper yang didapatkan dari dokumen-dokumen hasil peneltian baik di jurnal dan conference terkait dengan praktik-praktik security VLC yang pernah dilakukan dengan skema indoor maupun outdoor.

Equation Chapter 1 Section 1Cross Layer Design for Localization in Large-Scale Underwater Sensor Networks

Directory of Open Access Journals (Sweden)

Yuanfeng ZHANG

2014-02-01

Full Text Available There are many technical challenges for designing large-scale underwater sensor networks, especially the sensor node localization. Although many papers studied for large-scale sensor node localization, previous studies mainly study the location algorithm without the cross layer design for localization. In this paper, by utilizing the network hierarchical structure of underwater sensor networks, we propose a new large-scale underwater acoustic localization scheme based on cross layer design. In this scheme, localization is performed in a hierarchical way, and the whole localization process focused on the physical layer, data link layer and application layer. We increase the pipeline parameters which matched the acoustic channel, added in MAC protocol to increase the authenticity of the large-scale underwater sensor networks, and made analysis of different location algorithm. We conduct extensive simulations, and our results show that MAC layer protocol and the localization algorithm all would affect the result of localization which can balance the trade-off between localization accuracy, localization coverage, and communication cost.

Macular Choroidal Small-Vessel Layer, Sattler's Layer and Haller's Layer Thicknesses: The Beijing Eye Study.

Science.gov (United States)

Zhao, Jing; Wang, Ya Xing; Zhang, Qi; Wei, Wen Bin; Xu, Liang; Jonas, Jost B

2018-03-13

To study macular choroidal layer thickness, 3187 study participants from the population-based Beijing Eye Study underwent spectral-domain optical coherence tomography with enhanced depth imaging for thickness measurements of the macular small-vessel layer, including the choriocapillaris, medium-sized choroidal vessel layer (Sattler's layer) and large choroidal vessel layer (Haller's layer). In multivariate analysis, greater thickness of all three choroidal layers was associated (all P  0.05) associated with the prevalence of open-angle glaucoma or diabetic retinopathy. There was a tendency (0.07 > P > 0.02) toward thinner choroidal layers in chronic angle-closure glaucoma. The ratio of small-vessel layer thickness to total choroidal thickness increased (P layer and Haller's layer thickness to total choroidal thickness decreased. A higher ratio of small-vessel layer thickness to total choroidal thickness was significantly associated with a lower prevalence of AMD (early type, intermediate type, late geographic type). Axial elongation-associated and aging-associated choroidal thinning affected Haller's and Sattler's layers more markedly than the small-vessel layer. Non-exudative and exudative AMD, except for geographic atrophy, was associated with slightly increased choroidal thickness.

Guidelines for haptic interpersonal communication applications : an exploration of foot interaction styles

NARCIS (Netherlands)

Rovers, A.F.; Essen, van H.A.

2006-01-01

A new method for researching haptic interaction styles is presented, based on a layered interaction model and a classification of existing devices. The method is illustrated by designing a new foot interaction device. The aim of which is to enhance non-verbal communication over a computer network. A

Wireless communications resource management

CERN Document Server

Lee, B; Seo, H

2009-01-01

Wireless technologies continue to evolve to address the insatiable demand for faster response times, larger bandwidth, and reliable transmission. Yet as the industry moves toward the development of post 3G systems, engineers have consumed all the affordable physical layer technologies discovered to date. This has necessitated more intelligent and optimized utilization of available wireless resources. Wireless Communications Resource Managem ent, Lee, Park, and Seo cover all aspects of this critical topic, from the preliminary concepts and mathematical tools to detailed descriptions of all the resource management techniques. Readers will be able to more effectively leverage limited spectrum and maximize device battery power, as well as address channel loss, shadowing, and multipath fading phenomena.

How to use MPI communication in highly parallel climate simulations more easily and more efficiently.

Science.gov (United States)

Behrens, Jörg; Hanke, Moritz; Jahns, Thomas

2014-05-01

In this talk we present a way to facilitate efficient use of MPI communication for developers of climate models. Exploitation of the performance potential of today's highly parallel supercomputers with real world simulations is a complex task. This is partly caused by the low level nature of the MPI communication library which is the dominant communication tool at least for inter-node communication. In order to manage the complexity of the task, climate simulations with non-trivial communication patterns often use an internal abstraction layer above MPI without exploiting the benefits of communication aggregation or MPI-datatypes. The solution for the complexity and performance problem we propose is the communication library YAXT. This library is built on top of MPI and takes high level descriptions of arbitrary domain decompositions and automatically derives an efficient collective data exchange. Several exchanges can be aggregated in order to reduce latency costs. Examples are given which demonstrate the simplicity and the performance gains for selected climate applications.

Cross-Layer Handover Scheme for Multimedia Communications in Next Generation Wireless Networks

Directory of Open Access Journals (Sweden)

Lin Chun-Cheng

2010-01-01

Full Text Available In order to achieve seamless handover for real-time applications in the IP Multimedia Subsystem (IMS of next generation network, a multiprotocol combined handover mechanism is proposed in this paper. We combine SIP (Session Initiation Protocol, FMIP (Fast Mobile IPv6 Protocol, and MIH (Media Independent Handover protocols by cross-layer design and optimize those protocols' signaling flows to improve the performance of vertical handover. Theoretical analysis and simulation results illustrate that our proposed mechanism performs better than the original SIP and MIH combined handover mechanism in terms of service interruption time and packet loss.

Underwater Acoustic Wireless Sensor Networks: Advances and Future Trends in Physical, MAC and Routing Layers

NARCIS (Netherlands)

Climent, S.; Sanchez, A.; Capella, J.V.; Meratnia, Nirvana; Serrano, J.J.

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

Communication and Sensing Circuits on Cellulose

Directory of Open Access Journals (Sweden)

Federico Alimenti

2015-06-01

Full Text Available This paper proposes a review of several circuits for communication and wireless sensing applications implemented on cellulose-based materials. These circuits have been developed during the last years exploiting the adhesive copper laminate method. Such a technique relies on a copper adhesive tape that is shaped by a photo-lithographic process and then transferred to the hosting substrate (i.e., paper by means of a sacrificial layer. The presented circuits span from UHF oscillators to a mixer working at 24 GHz and constitute an almost complete set of building blocks that can be applied to a huge variety communication apparatuses. Each circuit is validated experimentally showing performance comparable with the state-of-the-art. This paper demonstrates that circuits on cellulose are capable of operating at record frequencies and that ultra- low cost, green i.e., recyclable and biodegradable materials can be a viable solution to realize high frequency hardware for the upcoming Internet of Things (IoT era.

FTR: Performance-Aware and Energy-Efficient Communication Protocol for Integrating Sensor Networks into the Internet

Directory of Open Access Journals (Sweden)

Sinung Suakanto

2014-11-01

Full Text Available Integrating sensor networks into the Internet brings many advantages. For example, users can monitor or control the state of the sensors remotely without visiting the field. Some researchers have proposed methods using a REST-based web service or HTTP to establish communication between sensors and server via the Internet. Unfortunately, as we know, HTTP is a best-effort service. In some cases this means that if the number of sensors increases the end-to-end Quality of Service will decrease. The end-to-end network delay increases, as well as the failure rate of data sending caused by HTTP timeouts. In this paper, we propose Finite Time Response (FTR HTTP as a communication protocol suitable for integrating sensor networks into the Internet. We have defined a cross-layer approach that coordinates between the application layer and the physical layer to control not only performance but also energy efficiency. The HTTP request-response delay measured at the application layer is used as the decision factor at the physical layer to control the active and sleep periods. We also propose a forced-sleep period as a control mechanism to guarantee average performance for all nodes. The experimental results have shown that FTR has the ability to maintain better performance, indicated by a lower average response time and a lower average timeout experience. Optimization is still needed to gain better performance and better energy efficiency while also considering the average value of the update time.

Digital Signal Processing for Optical Coherent Communication Systems

DEFF Research Database (Denmark)

Zhang, Xu

spectrum narrowing tolerance 112-Gb/s DP-QPSK optical coherent systems using digital adaptive equalizer. The demonstrated results show that off-line DSP algorithms are able to reduce the bit error rate (BER) penalty induced by signal spectrum narrowing. Third, we also investigate bi...... wavelength division multiplex (U-DWDM) optical coherent systems based on 10-Gbaud QPSK. We report U-DWDM 1.2-Tb/s QPSK coherent system achieving spectral efficiency of 4.0-bit/s/Hz. In the experimental demonstration, digital decision feed back equalizer (DFE) algorithms and a finite impulse response (FIR......In this thesis, digital signal processing (DSP) algorithms are studied to compensate for physical layer impairments in optical fiber coherent communication systems. The physical layer impairments investigated in this thesis include optical fiber chromatic dispersion, polarization demultiplexing...

Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture

Science.gov (United States)

Steele, Kerry D [Kennewick, WA; Anderson, Gordon A [Benton City, WA; Gilbert, Ronald W [Morgan Hill, CA

2011-02-01

Communications device identification methods, communications methods, wireless communications readers, wireless communications systems, and articles of manufacture are described. In one aspect, a communications device identification method includes providing identification information regarding a group of wireless identification devices within a wireless communications range of a reader, using the provided identification information, selecting one of a plurality of different search procedures for identifying unidentified ones of the wireless identification devices within the wireless communications range, and identifying at least some of the unidentified ones of the wireless identification devices using the selected one of the search procedures.

Pseudo-communication vs Quasi-communication

Directory of Open Access Journals (Sweden)

Елена Константиновна Черничкина

2016-12-01

Full Text Available The article is devoted to the analysis of such specific forms of human interaction as quasi- and pseudo-communication. The authors specify the terms which sometimes are used interchangeably. The aim of the conducted research is to find out and demonstrate existing differences and similarities of these communicative phenomena on the basis of theoretical and empirical analysis of the research material in the Russian and English languages. The authors describe communicative features of these phenomena and consider the reasons for such forms of communication and their increased use at present. The research material is represented fiction extracts, film scripts, jokes, print media, a collection of oral speech records both in Russian and English. The authors make use of the following research methods: definitional analysis (to define the terminology of the research, the method of linguistic observation and introspection (to select the communicative situations, the descriptive-analytical method and the method of comparative analysis (to identify similarities and differences of the target phenomena, and the conversational analysis method (to view productivity and effectiveness of a dialogue, etc. The classification of possible forms of their existence in different discourses is suggested. The authors assume that both pseudo- and quasi-communication are characterized as fictitious forms of human interaction with some noticeable violation of the basic communicative model. Pseudo-communication suffers from the discrepancy of the meaning of a coded and decoded message. The authors put forward the main parameters of scientific classification of it as follows: adequate understanding, intentionality, and the stage of communicative action where the failure takes place. At the same time they stress the necessity to distinguish the cases of pseudo talks from phatic and indirect communication. Quasi-communcation is marked by the lack of a real partner and hence

A Cross-Layer Wireless Sensor Network Energy-Efficient Communication Protocol for Real-Time Monitoring of the Long-Distance Electric Transmission Lines

Directory of Open Access Journals (Sweden)

Jun Yu

2015-01-01

Full Text Available Optimization of energy consumption in Wireless Sensor Network (WSN nodes has become a critical link that constrains the engineering application of the smart grid due to the fact that the smart grid is characterized by long-distance transmission in a special environment. The paper proposes a linear hierarchical network topological structure specific to WSN energy conservation in environmental monitoring of the long-distance electric transmission lines in the smart grid. Based on the topological structural characteristics and optimization of network layers, the paper also proposes a Topological Structure be Layered Configurations (TSLC routing algorithm to improve the quality of WSN data transmission performance. Coprocessing of the network layer and the media access control (MAC layer is achieved by using the cross-layer design method, accessing the status for the nodes in the network layer and obtaining the status of the network nodes of the MAC layer. It efficiently saves the energy of the whole network, improves the quality of the network service performance, and prolongs the life cycle of the network.

Security in Visible Light Communication: Novel Challenges and Opportunities

Directory of Open Access Journals (Sweden)

Christian ROHNER

2015-09-01

Full Text Available As LED lighting becomes increasingly ubiquitous, Visible Light Communication is attracting the interest of academia and industry as a complement to RF as the physical layer for the Internet of Things. Aside from its much greater spectral availability compared to RF, visible light has several attractive properties that may promote its uptake: its lack of health risks, its opportunities for spatial reuse, its relative immunity to multipath fading, its lack of electromagnetic interference, and its inherently secure nature: differently from RF, light does not penetrate through walls. In this paper, we outline the security implications of Visible Light Communication, review the existing contributions to this under-explored space, and survey the research opportunities that we envision for the near future.

User Needs and Advances in Space Wireless Sensing and Communications

Science.gov (United States)

Kegege, Obadiah

2017-01-01

Decades of space exploration and technology trends for future missions show the need for new approaches in space/planetary sensor networks, observatories, internetworking, and communications/data delivery to Earth. The User Needs to be discussed in this talk includes interviews with several scientists and reviews of mission concepts for the next generation of sensors, observatories, and planetary surface missions. These observatories, sensors are envisioned to operate in extreme environments, with advanced autonomy, whereby sometimes communication to Earth is intermittent and delayed. These sensor nodes require software defined networking capabilities in order to learn and adapt to the environment, collect science data, internetwork, and communicate. Also, some user cases require the level of intelligence to manage network functions (either as a host), mobility, security, and interface data to the physical radio/optical layer. For instance, on a planetary surface, autonomous sensor nodes would create their own ad-hoc network, with some nodes handling communication capabilities between the wireless sensor networks and orbiting relay satellites. A section of this talk will cover the advances in space communication and internetworking to support future space missions. NASA's Space Communications and Navigation (SCaN) program continues to evolve with the development of optical communication, a new vision of the integrated network architecture with more capabilities, and the adoption of CCSDS space internetworking protocols. Advances in wireless communications hardware and electronics have enabled software defined networking (DVB-S2, VCM, ACM, DTN, Ad hoc, etc.) protocols for improved wireless communication and network management. Developing technologies to fulfil these user needs for wireless communications and adoption of standardized communication/internetworking protocols will be a huge benefit to future planetary missions, space observatories, and manned missions

Photophysical behavior of layer-by-layer electrostatic self-assembled film of azo dye Chromotrope-2R and a polycation

Energy Technology Data Exchange (ETDEWEB)

Hansda, Chaitali [Department of Physics, Jadavpur University, Jadavpur, Kolkata 700032 (India); Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104 (India); Dutta, Bipan [Department of Physics, Sammilani Mahavidyalaya, Baghajatin Station, E.M. Bypass, Kolkata 700075 (India); Chakraborty, Utsav; Singha, Tanmoy [Department of Physics, Jadavpur University, Jadavpur, Kolkata 700032 (India); Hussain, Syed Arshad; Bhattacharjee, Debajyoti [Department of Physics, Tripura University, Suryamaninagar 799022, Tripura West (India); Paul, Sharmistha [West Bengal State Council of Science and Technology, Vigyan Chetana Bhavan, Sector-I, Salt Lake, Kolkata 700064 (India); Paul, Pabitra Kumar, E-mail: pabitra_tu@yahoo.co.in [Department of Physics, Jadavpur University, Jadavpur, Kolkata 700032 (India)

2016-10-15

This communication reports the fabrication of layer-by-layer electrostatic self-assembled films of an azo dye Chromotrope-2R (CH2R) and a Polycation poly(allylamine hydrochloride) (PAH) onto solid substrate. UV–vis absorption and steady state fluorescence emission spectroscopy successfully confirm the incorporation of dye molecules onto the PAH coated quartz substrate. The adsorption behavior of CH2R onto PAH backbone in LbL films highly depends upon the variation of the microenvironment namely pH of the dye solution from which the film was fabricated. PAH layer onto quartz substrate was able to swell sufficiently in the dye solution at very high pH. The Density functional theory was also utilized here to explain the origin of various spectral transitions from the ground electronic states for both in neutral and anionic form of CH2R. In LbL films the more closure association of dye molecules causes their aggregations which are reflected in their absorption and steady state fluorescence emission spectra when compared to those of pure dye solution. Atomic force microscopic images of LbL films assembled from CH2R aqueous solution at different pH clearly reveal the change in the surface morphology of the films and different degree of association of dye molecules in LbL films deposited at various pH of CH2R.

Photophysical behavior of layer-by-layer electrostatic self-assembled film of azo dye Chromotrope-2R and a polycation

International Nuclear Information System (INIS)

Hansda, Chaitali; Dutta, Bipan; Chakraborty, Utsav; Singha, Tanmoy; Hussain, Syed Arshad; Bhattacharjee, Debajyoti; Paul, Sharmistha; Paul, Pabitra Kumar

2016-01-01

This communication reports the fabrication of layer-by-layer electrostatic self-assembled films of an azo dye Chromotrope-2R (CH2R) and a Polycation poly(allylamine hydrochloride) (PAH) onto solid substrate. UV–vis absorption and steady state fluorescence emission spectroscopy successfully confirm the incorporation of dye molecules onto the PAH coated quartz substrate. The adsorption behavior of CH2R onto PAH backbone in LbL films highly depends upon the variation of the microenvironment namely pH of the dye solution from which the film was fabricated. PAH layer onto quartz substrate was able to swell sufficiently in the dye solution at very high pH. The Density functional theory was also utilized here to explain the origin of various spectral transitions from the ground electronic states for both in neutral and anionic form of CH2R. In LbL films the more closure association of dye molecules causes their aggregations which are reflected in their absorption and steady state fluorescence emission spectra when compared to those of pure dye solution. Atomic force microscopic images of LbL films assembled from CH2R aqueous solution at different pH clearly reveal the change in the surface morphology of the films and different degree of association of dye molecules in LbL films deposited at various pH of CH2R.

The use of communication technology in medicine

Science.gov (United States)

Reis, Howard P.

1991-01-01

NYNEX Science and Technology is engineering a multi-layered approach to multimedia communications by combining high-resolution images, video, voice, and text into a new fiber-optic service. The service, Media Broadband Service (MBS), is a network-based visual communications capability. It permits real time sharing of images in support of collaborative work among geographically dispersed locations. The health care industry was identified as a primary target market due to their need for high resolution images, the need to transport these images over great distances, and the need to achieve the transport in a short amount of time. The NYNEX Corporation, the current state of the MBS project, including the market needs driving the development of MBS, the overall design of the service, its current implementation and development status, and the progress of MBS projects underway for various customers participating in the initial service offering are described.

Novel Reduced-Feedback Wireless Communication Systems

KAUST Repository

Shaqfeh, Mohammad Obaidah; Alnuweiri, Hussein; Alouini, Mohamed-Slim

2011-01-01

We have recently contributed to this field and published several journal and conference papers. We are the pioneers to propose a novel reduced-feedback opportunistic scheduling scheme that combines many desired features including fairness in resources distribution across the active terminals and distributed processing at the MAC layer level. In addition our scheme operates close to the upper capacity limits of achievable transmission rates over wireless links. We have also proposed another hybrid scheme that enables adjusting the feedback load flexibly based on rates requirements. We are currently investigating other novel ideas to design reduced-feedback communication systems.

Epidemic mitigation via awareness propagation in communication networks: the role of time scales

Science.gov (United States)

Wang, Huijuan; Chen, Chuyi; Qu, Bo; Li, Daqing; Havlin, Shlomo

2017-07-01

The participation of individuals in multi-layer networks allows for feedback between network layers, opening new possibilities to mitigate epidemic spreading. For instance, the spread of a biological disease such as Ebola in a physical contact network may trigger the propagation of the information related to this disease in a communication network, e.g. an online social network. The information propagated in the communication network may increase the awareness of some individuals, resulting in them avoiding contact with their infected neighbors in the physical contact network, which might protect the population from the infection. In this work, we aim to understand how the time scale γ of the information propagation (speed that information is spread and forgotten) in the communication network relative to that of the epidemic spread (speed that an epidemic is spread and cured) in the physical contact network influences such mitigation using awareness information. We begin by proposing a model of the interaction between information propagation and epidemic spread, taking into account the relative time scale γ. We analytically derive the average fraction of infected nodes in the meta-stable state for this model (i) by developing an individual-based mean-field approximation (IBMFA) method and (ii) by extending the microscopic Markov chain approach (MMCA). We show that when the time scale γ of the information spread relative to the epidemic spread is large, our IBMFA approximation is better compared to MMCA near the epidemic threshold, whereas MMCA performs better when the prevalence of the epidemic is high. Furthermore, we find that an optimal mitigation exists that leads to a minimal fraction of infected nodes. The optimal mitigation is achieved at a non-trivial relative time scale γ, which depends on the rate at which an infected individual becomes aware. Contrary to our intuition, information spread too fast in the communication network could reduce the

Generalized expressions for variations in critical frequencies, electron densities and altitudes of the ionospheric layers

International Nuclear Information System (INIS)

Njau, E.C.

1990-12-01

We develop generalized mathematical expressions for time and space variations of peak electron densities of the ionospheric D, E, F1 and F2 layers as well as corresponding variations in the altitudes of the electron density peaks in each of these layers. On the basis of the Chapman characteristics of the E and F1 layers and other techniques, a generalized expression is developed for the electron density height profile of each of the four ionospheric layers. Consequently a generalized mathematical expression is developed for the entire electron density height profile of the whole ionosphere as a function of time, latitude and longitude. The latter mathematical expression may be used to compute or predict ionospheric parameters associated with ratio and satellite communications. Finally we show that some well documented equations on ionospheric parameters are simplified (or approximated) versions of some of our mathematical expressions. (author). 29 refs

Uplink Cross-Layer Scheduling with Differential QoS Requirements in OFDMA Systems

Directory of Open Access Journals (Sweden)

Chen Wei

2010-01-01

Full Text Available Fair and efficient scheduling is a key issue in cross-layer design for wireless communication systems, such as 3GPP LTE and WiMAX. However, few works have considered the multiaccess of the traffic with differential QoS requirements in wireless systems. In this paper, we will consider an OFDMA-based wireless system with four types of traffic associated with differential QoS requirements, namely, minimum reserved rate, maximum sustainable rate, maximum latency, and tolerant jitter. Given these QoS requirements, the traffic scheduling will be formulated into a cross-layer optimization problem, which is convex fortunately. By separating the power allocation through the waterfilling algorithm in each user, this problem will further reduce to a kind of continuous quadratic knapsack problem in the base station which yields low complexity. It is then demonstrated that the proposed cross-layer method cannot only guarantee the application layer QoS requirements, but also minimizes the integrated residual workload in the MAC layer. To further enhance the ability of QoS assurance in heavily loaded scenario, a call admission control scheme will also be proposed. The simulation results show that the QoS requirements for the four types of traffic are guaranteed effectively by the proposed algorithms.

Performance Analysis of Secondary Link with Cross-Layer Design and Cooperative Relay in Cognitive Radio Networks

KAUST Repository

Ma, Hao

2012-06-01

In this thesis, we investigate two different system infrastructures in underlay cognitive radio network, in which two popular techniques, cross-layer design and cooperative communication, are considered, respectively. In particular, we introduce the Aggressive Adaptive Modulation and Coding (A-AMC) into the cross-layer design and achieve the optimal boundary points in closed form to choose the AMC and A-AMC transmission modes by taking into account the Channel State Information (CSI) from the secondary transmitter to both the primary receiver and the secondary receiver. What’s more, for the cooperative communication design, we consider three different relay selection schemes: Partial Relay Selection, Opportunistic Relay Selection and Threshold Relay Selection. The Probability Density Functions (PDFs) of the Signal-to- Noise Ratio (SNR) in each hop for different selection schemes are provided, and then the exact closed-form expressions for the end-to-end packet loss rate in the secondary link considering the cooperation of the Decode-and-Forward (DF) relay for different relay selection schemes are derived.

Cell walls as a stage for intercellular communication regulating shoot meristem development

Directory of Open Access Journals (Sweden)

Toshiaki eTameshige

2015-05-01

Full Text Available Aboveground organs of plants are ultimately derived/generated from the shoot apical meristem (SAM, which is the proliferative tissue located at the apex of the stem. The SAM contains a population of stem cells that provide new cells for organ/tissue formation. The SAM is composed of distinct cell layers and zones with different properties. Primordia of lateral organs develop at the periphery of the SAM. The shoot apex is a dynamic and complex tissue, and as such intercellular communications among cells, layers and zones play significant roles in the coordination of cell proliferation, growth and differentiation to achieve elaborate morphogenesis. Recent findings have highlighted the importance of a number of singling molecules acting in the cell wall space for the intercellular communication, including classic phytohormones and secretory peptides. Moreover, accumulating evidences reveal that cell wall properties and their modifying enzymes modulate hormone actions. In this review, we overview how behaviors of singling molecules and changes of cell wall properties are integrated for the shoot meristem regulation.

Modelling multimedia teleservices with OSI upper layers framework: Short paper

Science.gov (United States)

Widya, I.; Vanrijssen, E.; Michiels, E.

The paper presents the use of the concepts and modelling principles of the Open Systems Interconnection (OSI) upper layers structure in the modelling of multimedia teleservices. It puts emphasis on the revised Application Layer Structure (OSI/ALS). OSI/ALS is an object based reference model which intends to coordinate the development of application oriented services and protocols in a consistent and modular way. It enables the rapid deployment and integrated use of these services. The paper emphasizes further on the nesting structure defined in OSI/ALS which allows the design of scalable and user tailorable/controllable teleservices. OSI/ALS consistent teleservices are moreover implementable on communication platforms of different capabilities. An analysis of distributed multimedia architectures which can be found in the literature, confirms the ability of the OSI/ALS framework to model the interworking functionalities of teleservices.

Barrier layer arrangement for conductive layers on silicon substrates

International Nuclear Information System (INIS)

Hung, L.S.; Agostinelli, J.A.

1990-01-01

This patent describes a circuit element comprised of a silicon substrate and a conductive layer located on the substrate. It is characterized in that the conductive layer consists essentially of a rare earth alkaline earth copper oxide and a barrier layer triad is interposed between the silicon substrate and the conductive layer comprised of a first triad layer located adjacent the silicon substrate consisting essentially of silica, a third triad layer remote from the silicon substrate consisting essentially of a least one Group 4 heavy metal oxide, and a second triad layer interposed between the first and third triad layers consisting essentially of a mixture of silica and at lease one Group 4 heavy metal oxide

A fusion networking model for smart grid power distribution backbone communication network based on PTN

Directory of Open Access Journals (Sweden)

Wang Hao

2016-01-01

Full Text Available In current communication network for distribution in Chinese power grid systems, the fiber communication backbone network for distribution and TD-LTE power private wireless backhaul network of power grid are both bearing by the SDH optical transmission network, which also carries the communication network of transformer substation and main electric. As the data traffic of the distribution communication and TD-LTE power private wireless network grow rapidly in recent years, it will have a big impact with the SDH network’s bearing capacity which is mainly used for main electric communication in high security level. This paper presents a fusion networking model which use a multiple-layer PTN network as the unified bearing of the TD-LTE power private wireless backhaul network and fiber communication backbone network for distribution. Network dataflow analysis shows that this model can greatly reduce the capacity pressure of the traditional SDH network as well as ensure the reliability of the transmission of the communication network for distribution and TD-LTE power private wireless network.

Invisible watermarking optical camera communication and compatibility issues of IEEE 802.15.7r1 specification

Science.gov (United States)

Le, Nam-Tuan

2017-05-01

Copyright protection and information security are two most considered issues of digital data following the development of internet and computer network. As an important solution for protection, watermarking technology has become one of the challenged roles in industry and academic research. The watermarking technology can be classified by two categories: visible watermarking and invisible watermarking. With invisible technique, there is an advantage on user interaction because of the visibility. By applying watermarking for communication, it will be a challenge and a new direction for communication technology. In this paper we will propose one new research on communication technology using optical camera communications (OCC) based invisible watermarking. Beside the analysis on performance of proposed system, we also suggest the frame structure of PHY and MAC layer for IEEE 802.15.7r1 specification which is a revision of visible light communication (VLC) standardization.

Three Pillars of Success: The Partners, The Messenger, The Communication Strategies

Science.gov (United States)

Turrin, M.; Ryan, W. B. F.; Pfirman, S. L.

2017-12-01

Our ability to deal with climate impacts in coastal cities and bring change, hinges on our ability to effectively communicate impacts. Incorporating sea level rise and climate impacts into city planning and community action plans is too often done in response to a devastating impact rather than through preventative planning. In New York the impact came in the form of Hurricane Sandy. Prior to Sandy, NYC, NY State and regional scientists had prepared planning documents, reports and communications directed at public officials and decision makers, warning of potential impacts from a changing climate. Presentations and reports identified the most exposed locations and infrastructure, but disbelief and a false sense of time mired any meaningful change. Effective communication about climate and impacts is at the root of planning and resilience. To be meaningful it must come from a trusted messenger, use well vetted materials that address both larger climate processes and drivers and local impacts, be accessible to the non-science community, and incorporate multiple modes of communication. The Polar Explorer: Sea Level app is a tool that has been used to this end (http://www.polarexplorer.org). An interactive multi-layered communication tool, it uses vetted data structured through a series of commonly asked questions and displayed through visualizations. We have been partnering with New York State, local community groups, and state and educational organizations to reach a broad cross section of the public with information useful for planning. We have co-presented at conferences for local planning and advisory groups, and incorporated the use of the app into local planning charrettes and have found the visualizations, interactivity of the delivery and the layered scaffolding make the app a useful tool for planners and decision makers. The app includes the physical science drivers of climate change and the social science impacts, and a look at the past the present and

Hydraulic Stability of Single-Layer Dolos and Accropode Armour Layers

DEFF Research Database (Denmark)

Christensen, M.; Burcharth, H. F.

1995-01-01

A new design for Dolos breakwater armour layers is presented: Dolos armour units are placed in a selected geometric pattern in a single layer. A series of model tests have been performed in order to determine the stability of such single-layer Dolos armour layers. The test results are presented...... and compared to the stability formula for the traditional double-layer, randomly placed Dolos armour layer design presented by Burcharth (1992). The results of a series of stability tests performed with Accropode® armour layers is presented and compared to the test results obtained with single-layer Dolos...... armour layers. Run-up and reflection are presented for both single-layer Dolos armour and Accropode armour....

Low-temperature atomic layer epitaxy of AlN ultrathin films by layer-by-layer, in-situ atomic layer annealing.

Science.gov (United States)

Shih, Huan-Yu; Lee, Wei-Hao; Kao, Wei-Chung; Chuang, Yung-Chuan; Lin, Ray-Ming; Lin, Hsin-Chih; Shiojiri, Makoto; Chen, Miin-Jang

2017-01-03

Low-temperature epitaxial growth of AlN ultrathin films was realized by atomic layer deposition (ALD) together with the layer-by-layer, in-situ atomic layer annealing (ALA), instead of a high growth temperature which is needed in conventional epitaxial growth techniques. By applying the ALA with the Ar plasma treatment in each ALD cycle, the AlN thin film was converted dramatically from the amorphous phase to a single-crystalline epitaxial layer, at a low deposition temperature of 300 °C. The energy transferred from plasma not only provides the crystallization energy but also enhances the migration of adatoms and the removal of ligands, which significantly improve the crystallinity of the epitaxial layer. The X-ray diffraction reveals that the full width at half-maximum of the AlN (0002) rocking curve is only 144 arcsec in the AlN ultrathin epilayer with a thickness of only a few tens of nm. The high-resolution transmission electron microscopy also indicates the high-quality single-crystal hexagonal phase of the AlN epitaxial layer on the sapphire substrate. The result opens a window for further extension of the ALD applications from amorphous thin films to the high-quality low-temperature atomic layer epitaxy, which can be exploited in a variety of fields and applications in the near future.

A Cross-Layer Optimization Approach for Energy Efficient Wireless Sensor Networks: Coalition-Aided Data Aggregation, Cooperative Communication, and Energy Balancing

Directory of Open Access Journals (Sweden)

Qinghai Gao

2007-01-01

Full Text Available We take a cross-layer optimization approach to study energy efficient data transport in coalition-based wireless sensor networks, where neighboring nodes are organized into groups to form coalitions and sensor nodes within one coalition carry out cooperative communications. In particular, we investigate two network models: (1 many-to-one sensor networks where data from one coalition are transmitted to the sink directly, and (2 multihop sensor networks where data are transported by intermediate nodes to reach the sink. For the many-to-one network model, we propose three schemes for data transmission from a coalition to the sink. In scheme 1, one node in the coalition is selected randomly to transmit the data; in scheme 2, the node with the best channel condition in the coalition transmits the data; and in scheme 3, all the nodes in the coalition transmit in a cooperative manner. Next, we investigate energy balancing with cooperative data transport in multihop sensor networks. Built on the above coalition-aided data transmission schemes, the optimal coalition planning is then carried out in multihop networks, in the sense that unequal coalition sizes are applied to minimize the difference of energy consumption among sensor nodes. Numerical analysis reveals that energy efficiency can be improved significantly by the coalition-aided transmission schemes, and that energy balancing across the sensor nodes can be achieved with the proposed coalition structures.

Development of Information Assurance Protocol for Low Bandwidth Nanosatellite Communications

Science.gov (United States)

2017-09-01

14. SUBJECT TERMS commercial off-the-shelf technology , nanosatellites, CubeSat, encrypted communications 15. NUMBER OF PAGES 161 16. PRICE...integrate with several physical layer technologies . While this protocol does provide some additional functionality at a lower cost, it is limited to...G. S. Vernam, “Secret signaling system.” U.S. Patent U.S. 1310719 A, 22 July 1919. [22] D. Kahn, Codebreakers: The Story of Secret Writing, New

Airborne wireless communication systems, airborne communication methods, and communication methods

Science.gov (United States)

Deaton, Juan D [Menan, ID; Schmitt, Michael J [Idaho Falls, ID; Jones, Warren F [Idaho Falls, ID

2011-12-13

An airborne wireless communication system includes circuitry configured to access information describing a configuration of a terrestrial wireless communication base station that has become disabled. The terrestrial base station is configured to implement wireless communication between wireless devices located within a geographical area and a network when the terrestrial base station is not disabled. The circuitry is further configured, based on the information, to configure the airborne station to have the configuration of the terrestrial base station. An airborne communication method includes answering a 911 call from a terrestrial cellular wireless phone using an airborne wireless communication system.

Seasonal variability in virtual height of ionospheric f/sub 2/ layer at the pakistan atmospheric region

International Nuclear Information System (INIS)

Jilani, A.A.; Afridi, F.A.K.; Mian, K.; Zai, M.A.K.Y.

2013-01-01

The aim of this study was to assess the seasonal variability in virtual height of ionospheric F/sub 2/ layer for Pakistan's atmospheric region (PAR). In this communication virtual height variations have been analyzed by the descriptive statistical techniques. These methodologies comprise an autoregressive strategy, linear regression and polynomial regression. The relevance of these models has been illuminated using predicted values of different parameters under the seasonal variation of ionospheric F/sub 2/ layer in virtual height that affect the radio wave propagation through the ionosphere. These techniques are implemented to theorize the physical process of varying the virtual heights that leads this study towards formulating the variations due to interaction of radio wave propagation with this ionospheric layer. (author)

Organising Documentation in Knowledge Evolution and Communication

Directory of Open Access Journals (Sweden)

Cristina De Castro

2007-06-01

Full Text Available The knowledge of a subject evolves in time due to many factors, such as better understanding, study of additional issues within the same subject, study of related work from other themes, etc. This can be achieved by individual work, direct cooperation with other people and, in general, knowledge sharing. In this context, and in the broader context of knowledge communication, the appropriate organisation of documentation plays a fundamental role, but is often very difficult to achieve. A layered architecture is here proposed for the development of a structured repository of documentation, here called knowledge-bibliography KB. The process of knowledge acquisition, evolution and communication is firstly considered, then the distributed nature of nowadays knowledge and the ways it is shared and transferred are taken into account. On the basis of the above considerations, a possible clustering of documentation collected by many people is defined. An LDAP-based architecture for the implementation of this structure is also discussed.

Dynamics of Gut-Brain Communication Underlying Hunger.

Science.gov (United States)

Beutler, Lisa R; Chen, Yiming; Ahn, Jamie S; Lin, Yen-Chu; Essner, Rachel A; Knight, Zachary A

2017-10-11

Communication between the gut and brain is critical for homeostasis, but how this communication is represented in the dynamics of feeding circuits is unknown. Here we describe nutritional regulation of key neurons that control hunger in vivo. We show that intragastric nutrient infusion rapidly and durably inhibits hunger-promoting AgRP neurons in awake, behaving mice. This inhibition is proportional to the number of calories infused but surprisingly independent of macronutrient identity or nutritional state. We show that three gastrointestinal signals-serotonin, CCK, and PYY-are necessary or sufficient for these effects. In contrast, the hormone leptin has no acute effect on dynamics of these circuits or their sensory regulation but instead induces a slow modulation that develops over hours and is required for inhibition of feeding. These findings reveal how layers of visceral signals operating on distinct timescales converge on hypothalamic feeding circuits to generate a central representation of energy balance. Copyright © 2017 Elsevier Inc. All rights reserved.

An Energy-Aware Trajectory Optimization Layer for sUAS

Science.gov (United States)

Silva, William A.

The focus of this work is the implementation of an energy-aware trajectory optimization algorithm that enables small unmanned aircraft systems (sUAS) to operate in unknown, dynamic severe weather environments. The software is designed as a component of an Energy-Aware Dynamic Data Driven Application System (EA-DDDAS) for sUAS. This work addresses the challenges of integrating and executing an online trajectory optimization algorithm during mission operations in the field. Using simplified aircraft kinematics, the energy-aware algorithm enables extraction of kinetic energy from measured winds to optimize thrust use and endurance during flight. The optimization layer, based upon a nonlinear program formulation, extracts energy by exploiting strong wind velocity gradients in the wind field, a process known as dynamic soaring. The trajectory optimization layer extends the energy-aware path planner developed by Wenceslao Shaw-Cortez te{Shaw-cortez2013} to include additional mission configurations, simulations with a 6-DOF model, and validation of the system with flight testing in June 2015 in Lubbock, Texas. The trajectory optimization layer interfaces with several components within the EA-DDDAS to provide an sUAS with optimal flight trajectories in real-time during severe weather. As a result, execution timing, data transfer, and scalability are considered in the design of the software. Severe weather also poses a measure of unpredictability to the system with respect to communication between systems and available data resources during mission operations. A heuristic mission tree with different cost functions and constraints is implemented to provide a level of adaptability to the optimization layer. Simulations and flight experiments are performed to assess the efficacy of the trajectory optimization layer. The results are used to assess the feasibility of flying dynamic soaring trajectories with existing controllers as well as to verify the interconnections between

Wireless Physical Layer Security: On the Performance Limit of Secret-Key Agreement

KAUST Repository

Zorgui, Marwen

2015-05-01

Physical layer security (PLS) is a new paradigm aiming at securing communications between legitimate parties at the physical layer. Conventionally, achieving confidentiality in communication networks relies on cryptographic techniques such as public-key cryptography, secret-key distribution and symmetric encryption. Such techniques are deemed secure based on the assumption of limited computational abilities of a wiretapper. Given the relentless progress in computational capacities and the dynamic topology and proliferation of modern wireless networks, the relevance of the previous techniques in securing communications is more and more questionable and less and less reliable. In contrast to this paradigm, PLS does not assume a specific computational power at any eavesdropper, its premise to guarantee provable security via employing channel coding techniques at the physical layer exploiting the inherent randomness in most communication systems. In this dissertation, we investigate a particular aspect of PLS, which is secret-key agreement, also known as secret-sharing. In this setup, two legitimate parties try to distill a secret-key via the observation of correlated signals through a noisy wireless channel, in the presence of an eavesdropper who must be kept ignorant of the secret-key. Additionally, a noiseless public channel is made available to the legitimate parties to exchange public messages that are also accessible to the eavesdropper. Recall that key agreement is an important aspect toward realizing secure communications in the sense that the key can be used in a one-time pad scheme to send the confidential message. In the first part, our focus is on secret-sharing over Rayleigh fading quasi-static channels. We study the fundamental relationship relating the probability of error and a given target secret-key rate in the high power regime. This is characterized through the diversity multiplexing tradeoff (DMT) concept, that we define for our model and then

Organizational Communication: Communication and Motivation in The Workplace

Directory of Open Access Journals (Sweden)

Sari Ramadanty

2016-01-01

Full Text Available Every human activity was basically driven by the motivation. Work motivation was a condition or an energy that directed employees to achieve organizational goals of the company. Nowadays, the development of organizational communication saw the communication as one of the most dominant and important activity in the organization and it could be able to motivate employees. The purpose of this study was to reveal how the role of the communication that occurs within the organization could give the motivation to employee. The problem of the research was the relationship employee motivation with factors of communication, such as nonverbal communication, interpersonal communication leadership and communication climate. The method used descriptive qualitative method. Methods of data collection of this study were literature study. Research finds that nonverbal communication, interpersonal communication leadership and communication climate have a significant role to form employee motivation. Nonverbal communication has slightly strong role in shaping the positive motivation to employee. The role includes body communication, facial communication and eye communication. Interpersonal communication leader is based on the satisfaction level of information between management and employees. Management and transparency in openness in downward communication under the form of information from superiors are by listening the communication between supervisors and employees are running smoothly. 

Data communications and computer communications network

International Nuclear Information System (INIS)

Kim, Jang Gwon; Gu, Chang Hoe

2005-03-01

This textbook is composed of twelve chapters, which are communication network introduction, foundation of data communication, data link control, circuit switching system, packet switching system, multiple access communication system, protocol and architecture, LAN, MAN communication network, integrated service digital network, internet and Asymmetric digital subscriber Line and Wireless Local Loop. Each chapter has the introduction of the technique, structure, function and practice problems. It also has the appendix on electricity and communication standards organization, characteristic table and glossary.

Processes for multi-layer devices utilizing layer transfer

Science.gov (United States)

Nielson, Gregory N; Sanchez, Carlos Anthony; Tauke-Pedretti, Anna; Kim, Bongsang; Cederberg, Jeffrey; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J

2015-02-03

A method includes forming a release layer over a donor substrate. A plurality of devices made of a first semiconductor material are formed over the release layer. A first dielectric layer is formed over the plurality of devices such that all exposed surfaces of the plurality of devices are covered by the first dielectric layer. The plurality of devices are chemically attached to a receiving device made of a second semiconductor material different than the first semiconductor material, the receiving device having a receiving substrate attached to a surface of the receiving device opposite the plurality of devices. The release layer is etched to release the donor substrate from the plurality of devices. A second dielectric layer is applied over the plurality of devices and the receiving device to mechanically attach the plurality of devices to the receiving device.

Econometric Models of Dependencies of the Tariffs in the Market for Information and Communication Services

Directory of Open Access Journals (Sweden)

Skrypnyk Andrii V.

2018-03-01

Full Text Available The market for information and communication services in Ukraine is analyzed based on statistical data. Its main segments by revenue, namely mobile communications and Internet services, are identified. The main regularities of setting tariffs for these services in countries of the world are determined, depending on the welfare of the population, the democracy index, the index of information and communication technologies, as well as the corruption perception index. Scatter diagrams of dependence of the tariffs on mobile communications and the Internet on the GDP per capita are built. The parameters of single-factor and multifactorial models of influence of the GDP per capita, the index of democracy, and the index of information and communication technologies on tariffs for mobile communications and the Internet by regions of the world are investigated. The conclusion is drawn that the tariff policy of the operators of Ukraine is aimed at reaching broad layers of the population, and even after taking into account the effect of the level of the country’s economic development, tariffs remain too low.

Passing Corrupt Data Across Network Layers: An Overview of Recent Developments and Issues

Directory of Open Access Journals (Sweden)

Michael Welzl

2005-02-01

Full Text Available Recent Internet developments seem to make a point for passing corrupt data from the link to the network layer and above instead of ensuring data integrity with a checksum and ARQ. We give an overview of these efforts (the UDP Lite and DCCP protocols and explain which circumstances would justify delivery of erroneous data; clearly, the missing piece in the puzzle is efficient and meaningful interlayer communication.

Enhancing Secrecy With Multiantenna Transmission in Millimeter Wave Vehicular Communication Systems

KAUST Repository

Eltayeb, Mohammed E.; Choi, Junil; Al-Naffouri, Tareq Y.; Heath, Robert W.

2017-01-01

Millimeter wave (mmWave) vehicular communication systems will provide an abundance of bandwidth for the exchange of raw sensor data and support driver-assisted and safety-related functionalities. Lack of secure communication links, however, may lead to abuses and attacks that jeopardize the efficiency of transportation systems and the physical safety of drivers. In this paper, we propose two physical layer (PHY) security techniques for vehicular mmWave communication systems. The first technique uses multiple antennas with a single radio-frequency (RF) chain to transmit information symbols to a target receiver and noise-like signals in nonreceiver directions. The second technique uses multiple antennas with a few RF chains to transmit information symbols to a target receiver and opportunistically inject artificial noise in controlled directions, thereby reducing interference in vehicular environments. Theoretical and numerical results show that the proposed techniques provide higher secrecy rate when compared to traditional PHY security techniques that require digital or more complex antenna architectures.

Enhancing Secrecy With Multiantenna Transmission in Millimeter Wave Vehicular Communication Systems

KAUST Repository

Eltayeb, Mohammed E.

2017-03-14

Millimeter wave (mmWave) vehicular communication systems will provide an abundance of bandwidth for the exchange of raw sensor data and support driver-assisted and safety-related functionalities. Lack of secure communication links, however, may lead to abuses and attacks that jeopardize the efficiency of transportation systems and the physical safety of drivers. In this paper, we propose two physical layer (PHY) security techniques for vehicular mmWave communication systems. The first technique uses multiple antennas with a single radio-frequency (RF) chain to transmit information symbols to a target receiver and noise-like signals in nonreceiver directions. The second technique uses multiple antennas with a few RF chains to transmit information symbols to a target receiver and opportunistically inject artificial noise in controlled directions, thereby reducing interference in vehicular environments. Theoretical and numerical results show that the proposed techniques provide higher secrecy rate when compared to traditional PHY security techniques that require digital or more complex antenna architectures.

Intervehicle Communication Research – Communication Scenarios

Directory of Open Access Journals (Sweden)

Šarūnas Stanaitis

2011-03-01

Full Text Available Recently intervehicle communications are attracting much attention from industry and academia. Upcoming standard for intervehicle communication IEEE 802.11p, known as Wireless Access in Vehicular Environments (WAVE, is still in its draft stage, but already coming into final standardization phase. Problematic, regarding mobile WAVE nodes, are described in several articles, simulations prepared and experiments done. But most of these works do not consider possible maximal communication load. This paper presents intervehicle communication scenario in respect to radio communications, mobility and other aspects of vehicular environments.Article in English

S-Layer Based Bio-Imprinting - Synthetic S-Layer Polymers

Science.gov (United States)

2015-07-09

AFRL-OSR-VA-TR-2015-0161 S-Layer Based Bio- Imprinting - Synthetic S-Layer Polymers Dietmar Pum ZENTRUM FUER NANOBIOTECHNOLOGIE Final Report 07/09...COVERED (From - To)      01-06-2012 to 31-05-2015 4.  TITLE AND SUBTITLE S-Layer Based Bio- Imprinting - Synthetic S-Layer Polymers 5a.  CONTRACT...technology for the fabrication of nano patterned thin film imprints by using functional S-layer protein arrays as templates. The unique feature of

Multiple Temporalities, Layered Histories

Directory of Open Access Journals (Sweden)

Steven Pearson

2017-11-01

Full Text Available In Quotational Practices: Repeating the Future in Contemporary Art, Patrick Greaney asserts, “the past matters not only because of what actually happened but also because of the possibilities that were not realized and that still could be. Quotation evokes those possibilities. By repeating the past, artists and writers may be attempting to repeat that past’s unrealized futures.”[1]  In the information age, the Internet, for instance, provides us an expanded collection of visual information—quite literally available at our fingertips—summoning together aspects of the past and possibilities of the future into a boundless present. Sketchbook Revisions (2014–2015, a series of mixed-media paintings, represents my attempt to communicate the ways in which I experience my contemporary moment constructed from multiple temporalities excavated from my past. This body of work combines fragments of representational paintings created between 1995 and 2003 and nonrepresentational renderings produced between 2003 and 2014. Using traditional tracing paper and graphic color, I randomly select moments of my previous work to transfer and layer over selected areas of already-filled pages of a sketchbook I used from 2003 to 2004. These sketches depict objects I encountered in studio art classrooms and iconic architecture on the campus of McDaniel College, and often incorporate teaching notes. The final renditions of fragmented and layered histories enact the ways that we collectively experience multiple temporalities in the present. Quoting my various bodies of work, Sketchbook Revisions challenges both material and conceptual boundaries that determine fixed notions of artistic identity.

The Application of Layer Theory to Design: The Control Layer

Science.gov (United States)

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…

A High-Efficiency Uneven Cluster Deployment Algorithm Based on Network Layered for Event Coverage in UWSNs

Directory of Open Access Journals (Sweden)

Shanen Yu

2016-12-01

Full Text Available Most existing deployment algorithms for event coverage in underwater wireless sensor networks (UWSNs usually do not consider that network communication has non-uniform characteristics on three-dimensional underwater environments. Such deployment algorithms ignore that the nodes are distributed at different depths and have different probabilities for data acquisition, thereby leading to imbalances in the overall network energy consumption, decreasing the network performance, and resulting in poor and unreliable late network operation. Therefore, in this study, we proposed an uneven cluster deployment algorithm based network layered for event coverage. First, according to the energy consumption requirement of the communication load at different depths of the underwater network, we obtained the expected value of deployment nodes and the distribution density of each layer network after theoretical analysis and deduction. Afterward, the network is divided into multilayers based on uneven clusters, and the heterogeneous communication radius of nodes can improve the network connectivity rate. The recovery strategy is used to balance the energy consumption of nodes in the cluster and can efficiently reconstruct the network topology, which ensures that the network has a high network coverage and connectivity rate in a long period of data acquisition. Simulation results show that the proposed algorithm improves network reliability and prolongs network lifetime by significantly reducing the blind movement of overall network nodes while maintaining a high network coverage and connectivity rate.

A two layer chaotic encryption scheme of secure image transmission for DCT precoded OFDM-VLC transmission

Science.gov (United States)

Wang, Zhongpeng; Chen, Fangni; Qiu, Weiwei; Chen, Shoufa; Ren, Dongxiao

2018-03-01

In this paper, a two-layer image encryption scheme for a discrete cosine transform (DCT) precoded orthogonal frequency division multiplexing (OFDM) visible light communication (VLC) system is proposed. Firstly, in the proposed scheme the transmitted image is first encrypted by a chaos scrambling sequence,which is generated from the hybrid 4-D hyper- and Arnold map in the upper-layer. After that, the encrypted image is converted into digital QAM modulation signal, which is re-encrypted by chaos scrambling sequence based on Arnold map in physical layer to further enhance the security of the transmitted image. Moreover, DCT precoding is employed to improve BER performance of the proposed system and reduce the PAPR of OFDM signal. The BER and PAPR performances of the proposed system are evaluated by simulation experiments. The experiment results show that the proposed two-layer chaos scrambling schemes achieve image secure transmission for image-based OFDM VLC. Furthermore, DCT precoding can reduce the PAPR and improve the BER performance of OFDM-based VLC.

The Visual Communication or Graphic Communication Dilemma

Science.gov (United States)

Fecik, John T.

1975-01-01

The author reviews the history of communication and communications technology, considers differences between "visual communication" and "graphic communication," and comments on "seeds of revolution" in the industry. He offers four components of an educational structure or organization titled "graphic…

cMsg - A general purpose, publish-subscribe, interprocess communication implementation and framework

International Nuclear Information System (INIS)

Timmer, C; Abbott, D; Gyurjyan, V; Heyes, G; Jastrzembski, E; Wolin, E

2008-01-01

cMsg is software used to send and receive messages in the Jefferson Lab online and runcontrol systems. It was created to replace the several IPC software packages in use with a single API. cMsg is asynchronous in nature, running a callback for each message received. However, it also includes synchronous routines for convenience. On the framework level, cMsg is a thin API layer in Java, C, or C++ that can be used to wrap most message-based interprocess communication protocols. The top layer of cMsg uses this same API and multiplexes user calls to one of many such wrapped protocols (or domains) based on a URL-like string which we call a Uniform Domain Locator or UDL. One such domain is a complete implementation of a publish-subscribe messaging system using network communications and written in Java (user APIs in C and C++ too). This domain is built in a way which allows it to be used as a proxy server to other domains (protocols). Performance is excellent allowing the system not only to be used for messaging but also as a data distribution system

Derivation of Zagarola-Smits scaling in zero-pressure-gradient turbulent boundary layers

Science.gov (United States)

Wei, Tie; Maciel, Yvan

2018-01-01

This Rapid Communication derives the Zagarola-Smits scaling directly from the governing equations for zero-pressure-gradient turbulent boundary layers (ZPG TBLs). It has long been observed that the scaling of the mean streamwise velocity in turbulent boundary layer flows differs in the near surface region and in the outer layer. In the inner region of small-velocity-defect boundary layers, it is generally accepted that the proper velocity scale is the friction velocity, uτ, and the proper length scale is the viscous length scale, ν /uτ . In the outer region, the most generally used length scale is the boundary layer thickness, δ . However, there is no consensus on velocity scales in the outer layer. Zagarola and Smits [ASME Paper No. FEDSM98-4950 (1998)] proposed a velocity scale, U ZS=(δ1/δ ) U∞ , where δ1 is the displacement thickness and U∞ is the freestream velocity. However, there are some concerns about Zagarola-Smits scaling due to the lack of a theoretical base. In this paper, the Zagarola-Smits scaling is derived directly from a combination of integral, similarity, and order-of-magnitude analysis of the mean continuity equation. The analysis also reveals that V∞, the mean wall-normal velocity at the edge of the boundary layer, is a proper scale for the mean wall-normal velocity V . Extending the analysis to the streamwise mean momentum equation, we find that the Reynolds shear stress in ZPG TBLs scales as U∞V∞ in the outer region. This paper also provides a detailed analysis of the mass and mean momentum balance in the outer region of ZPG TBLs.

Methodology for the specification of communication activities within the framework of a multi-layered architecture: Toward the definition of a knowledge base

Science.gov (United States)

Amyay, Omar

A method defined in terms of synthesis and verification steps is presented. The specification of the services and protocols of communication within a multilayered architecture of the Open Systems Interconnection (OSI) type is an essential issue for the design of computer networks. The aim is to obtain an operational specification of the protocol service couple of a given layer. Planning synthesis and verification steps constitute a specification trajectory. The latter is based on the progressive integration of the 'initial data' constraints and verification of the specification originating from each synthesis step, through validity constraints that characterize an admissible solution. Two types of trajectories are proposed according to the style of the initial specification of the service protocol couple: operational type and service supplier viewpoint; knowledge property oriented type and service viewpoint. Synthesis and verification activities were developed and formalized in terms of labeled transition systems, temporal logic and epistemic logic. The originality of the second specification trajectory and the use of the epistemic logic are shown. An 'artificial intelligence' approach enables a conceptual model to be defined for a knowledge base system for implementing the method proposed. It is structured in three levels of representation of the knowledge relating to the domain, the reasoning characterizing synthesis and verification activities and the planning of the steps of a specification trajectory.

Layer-by-layer cell membrane assembly

Science.gov (United States)

Matosevic, Sandro; Paegel, Brian M.

2013-11-01

Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

Communication, Communication, Communication! Growth through Laboratory Instructing

Science.gov (United States)

Peterson, Jamie J.; DeAngelo, Samantha; Mack, Nancy; Thompson, Claudia; Cooper, Jennifer; Sesma, Arturo, Jr.

2014-01-01

This study examined gains undergraduate students made in their communication and collaboration skills when they served as peer teachers, i.e., laboratory instructors (LIs), for a General Psychology laboratory. Self-ratings of communication and collaboration skills were completed before and after teaching the laboratory. When compared to before the…

Assembly of 1D nanofibers into a 2D bi-layered composite nanofibrous film with different functionalities at the two layers via layer-by-layer electrospinning.

Science.gov (United States)

Wang, Zijiao; Ma, Qianli; Dong, Xiangting; Li, Dan; Xi, Xue; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

2016-12-21

A two-dimensional (2D) bi-layered composite nanofibrous film assembled by one-dimensional (1D) nanofibers with trifunctionality of electrical conduction, magnetism and photoluminescence has been successfully fabricated by layer-by-layer electrospinning. The composite film consists of a polyaniline (PANI)/Fe 3 O 4 nanoparticle (NP)/polyacrylonitrile (PAN) tuned electrical-magnetic bifunctional layer on one side and a Tb(TTA) 3 (TPPO) 2 /polyvinylpyrrolidone (PVP) photoluminescent layer on the other side, and the two layers are tightly combined face-to-face together into the novel bi-layered composite film of trifunctionality. The brand-new film has totally different characteristics at the double layers. The electrical conductivity and magnetism of the electrical-magnetic bifunctional layer can be, respectively, tunable via modulating the PANI and Fe 3 O 4 NP contents, and the highest electrical conductivity can reach up to the order of 10 -2 S cm -1 , and predominant intense green emission at 545 nm is obviously observed in the photoluminescent layer under the excitation of 357 nm single-wavelength ultraviolet light. More importantly, the luminescence intensity of the photoluminescent layer remains almost unaffected by the electrical-magnetic bifunctional layer because the photoluminescent materials have been successfully isolated from dark-colored PANI and Fe 3 O 4 NPs. By comparing with the counterpart single-layered composite nanofibrous film, it is found that the bi-layered composite nanofibrous film has better performance. The novel bi-layered composite nanofibrous film with trifunctionality has potential in the fields of nanodevices, molecular electronics and biomedicine. Furthermore, the design conception and fabrication technique for the bi-layered multifunctional film provide a new and facile strategy towards other films of multifunctionality.

Marine Atmospheric Surface Layer and Its Application to Electromagnetic Wave Propagation

Science.gov (United States)

Wang, Q.

2015-12-01

An important application of the atmospheric surface layer research is to characterize the near surface vertical gradients in temperature and humidity in order to predict radar and radio communication conditions in the environment. In this presentation, we will give an overview of a new research initiative funded under the Office of Naval Research (ONR) Multi-University Research Initiative (MURI): the Coupled Air-Sea Processes and EM Ducting Research (CASPER). The objective is to fully characterize the marine atmospheric boundary layer (MABL) as an electromagnetic (EM) propagation environment with the emphasis of spatial and temporal heterogeneities and surface wave/swell effects, both of which contravene the underlying assumptions of Monin-Obukhov Similarity Theory (MOST) used in coupled environmental forecast models. Furthermore, coastal variability in the inversion atop the MABL presents a challenge to forecast models and also causes practical issues in EM prediction models. These issues are the target of investigation of CASPER. CASPER measurement component includes two major field campaigns: CASPER-East (2015 Duck, NC) and CASPER-West (2018 southern California). This presentation will show the extensive measurements to be made during the CASPER -East field campaign with the focus on the marine atmospheric surface layer measurements with two research vessels, two research aircraft, surface flux buoy, wave gliders, ocean gliders, tethered balloons, and rawinsondes. Unlike previous research on the marine surface layer with the focus on surface fluxes and surface flux parameterization, CASPER field campaigns also emphasize of the surface layer profiles and the validation of the surface layer flux-profile relationship originally derived over land surfaces. Results from CASPER pilot experiment and preliminary results from CASPER-East field campaign will be discussed.

Gastroesophageal anastomosis: single-layer versus double-layer technique

International Nuclear Information System (INIS)

Aslam, V.A.; Bilal, A.; Khan, A.; Ahmed, M.

2008-01-01

Considerable controversy exists regarding the optimum technique for gastroesophageal anastomosis. Double layer technique has long been considered important for safe healing but there is evidence that single layer technique is also safe and can be performed in much shorter time. The purpose of this study was to compare the outcome of single layer and double layer techniques for gastroesophageal anastomosis. A prospective randomized study was conducted in cardiothoracic unit, Lady Reading Hospital from Jan 2006 to Jan 2008. Fifty patients with oesophageal carcinoma undergoing subtotal oesophagectomy were randomized to have the anastomosis by single layer continuous or double layer continuous technique (group A (n=24) and B (n=26) respectively). The demographic data, operative and anastomosis time, postoperative complications and hospital mortality were recorded on a proforma and analyzed on SPSS 10. There was no significant difference between group A and B in terms of age, gender, postoperative complications and duration of hospital stay. Anastomotic leak occurred in 4.2% patients in group A and 7.7% in group B (p=NS). Mean anastomosis time was 10.04 minutes in group A and 19.2 minutes in group B (p=0.0001). Mean operative time was 163.83 minutes and 170.96 minutes in group A and B respectively. Overall hospital mortality was 2%; no deaths occurred due to anastomotic leak. Single layer continuous technique is equally safe and can be performed in shorter time and at a lower cost than the double layer technique. (author)

L2-LBMT: A Layered Load Balance Routing Protocol for underwater multimedia data transmission

Science.gov (United States)

Lv, Ze; Tang, Ruichun; Tao, Ye; Sun, Xin; Xu, Xiaowei

2017-12-01

Providing highly efficient underwater transmission of mass multimedia data is challenging due to the particularities of the underwater environment. Although there are many schemes proposed to optimize the underwater acoustic network communication protocols, from physical layer, data link layer, network layer to transport layer, the existing routing protocols for underwater wireless sensor network (UWSN) still cannot well deal with the problems in transmitting multimedia data because of the difficulties involved in high energy consumption, low transmission reliability or high transmission delay. It prevents us from applying underwater multimedia data to real-time monitoring of marine environment in practical application, especially in emergency search, rescue operation and military field. Therefore, the inefficient transmission of marine multimedia data has become a serious problem that needs to be solved urgently. In this paper, A Layered Load Balance Routing Protocol (L2-LBMT) is proposed for underwater multimedia data transmission. In L2-LBMT, we use layered and load-balance Ad Hoc Network to transmit data, and adopt segmented data reliable transfer (SDRT) protocol to improve the data transport reliability. And a 3-node variant of tornado (3-VT) code is also combined with the Ad Hoc Network to transmit little emergency data more quickly. The simulation results show that the proposed protocol can balance energy consumption of each node, effectively prolong the network lifetime and reduce transmission delay of marine multimedia data.

Streetlight Control System Based on Wireless Communication over DALI Protocol

Science.gov (United States)

Bellido-Outeiriño, Francisco José; Quiles-Latorre, Francisco Javier; Moreno-Moreno, Carlos Diego; Flores-Arias, José María; Moreno-García, Isabel; Ortiz-López, Manuel

2016-01-01

Public lighting represents a large part of the energy consumption of towns and cities. Efficient management of public lighting can entail significant energy savings. This work presents a smart system for managing public lighting networks based on wireless communication and the DALI protocol. Wireless communication entails significant economic savings, as there is no need to install new wiring and visual impacts and damage to the facades of historical buildings in city centers are avoided. The DALI protocol uses bidirectional communication with the ballast, which allows its status to be controlled and monitored at all times. The novelty of this work is that it tackles all aspects related to the management of public lighting: a standard protocol, DALI, was selected to control the ballast, a wireless node based on the IEEE 802.15.4 standard with a DALI interface was designed, a network layer that considers the topology of the lighting network has been developed, and lastly, some user-friendly applications for the control and maintenance of the system by the technical crews of the different towns and cities have been developed. PMID:27128923

Streetlight Control System Based on Wireless Communication over DALI Protocol.

Science.gov (United States)

Bellido-Outeiriño, Francisco José; Quiles-Latorre, Francisco Javier; Moreno-Moreno, Carlos Diego; Flores-Arias, José María; Moreno-García, Isabel; Ortiz-López, Manuel

2016-04-27

Public lighting represents a large part of the energy consumption of towns and cities. Efficient management of public lighting can entail significant energy savings. This work presents a smart system for managing public lighting networks based on wireless communication and the DALI protocol. Wireless communication entails significant economic savings, as there is no need to install new wiring and visual impacts and damage to the facades of historical buildings in city centers are avoided. The DALI protocol uses bidirectional communication with the ballast, which allows its status to be controlled and monitored at all times. The novelty of this work is that it tackles all aspects related to the management of public lighting: a standard protocol, DALI, was selected to control the ballast, a wireless node based on the IEEE 802.15.4 standard with a DALI interface was designed, a network layer that considers the topology of the lighting network has been developed, and lastly, some user-friendly applications for the control and maintenance of the system by the technical crews of the different towns and cities have been developed.

A matching approach to communicate through the plasma sheath surrounding a hypersonic vehicle

International Nuclear Information System (INIS)

Gao, Xiaotian; Jiang, Binhao

2015-01-01

In order to overcome the communication blackout problem suffered by hypersonic vehicles, a matching approach has been proposed for the first time in this paper. It utilizes a double-positive (DPS) material layer surrounding a hypersonic vehicle antenna to match with the plasma sheath enclosing the vehicle. Analytical analysis and numerical results indicate a resonance between the matched layer and the plasma sheath will be formed to mitigate the blackout problem in some conditions. The calculated results present a perfect radiated performance of the antenna, when the match is exactly built between these two layers. The effects of the parameters of the plasma sheath have been researched by numerical methods. Based on these results, the proposed approach is easier to realize and more flexible to the varying radiated conditions in hypersonic flight comparing with other methods

Emulation Platform for Cyber Analysis of Wireless Communication Network Protocols

Energy Technology Data Exchange (ETDEWEB)

Van Leeuwen, Brian P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Eldridge, John M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-11-01

Wireless networking and mobile communications is increasing around the world and in all sectors of our lives. With increasing use, the density and complexity of the systems increase with more base stations and advanced protocols to enable higher data throughputs. The security of data transported over wireless networks must also evolve with the advances in technologies enabling more capable wireless networks. However, means for analysis of the effectiveness of security approaches and implementations used on wireless networks are lacking. More specifically a capability to analyze the lower-layer protocols (i.e., Link and Physical layers) is a major challenge. An analysis approach that incorporates protocol implementations without the need for RF emissions is necessary. In this research paper several emulation tools and custom extensions that enable an analysis platform to perform cyber security analysis of lower layer wireless networks is presented. A use case of a published exploit in the 802.11 (i.e., WiFi) protocol family is provided to demonstrate the effectiveness of the described emulation platform.

Revisiting Communicative Competence in Augmentative and Alternative Communication.

Science.gov (United States)

Tsai, Meng-Ju

2016-01-01

This tutorial paper is to explore the novel nature of communicative competence in augmentative and alternative communication (AAC) practice by comparing it to communicative competence in naturally verbal dyadic communication. This paper first reviews the four domains of communicative competence in AAC practice. Second, it examines competence in dyadic communications between naturally verbal people without disabilities, deriving new insights and using these to analyze the evolution of communicative competence in AAC practice. Communicative competence in AAC practice should be reconceptualized from a new perspective as dyadic, learned, co-constructed, and of relative value, ascertained through performance. In the past decades, the study of communicative competence in AAC practice has primarily focused on individual persons who use AAC. However, the conceptualization of communicative competence should shift away from an individualized construct toward a dyadic construct. This leads to a discussion of potential implications and future research directions. This paper might offer AAC researchers and practitioners an opportunity to deepen their understanding of communicative competence and promote more positive outcomes for people who use AAC. © 2017 S. Karger AG, Basel.

Communications article

KAUST Repository

Fariborzi, Hossein

2017-07-20

Seamless, covert communications using a communications system integrated or incorporated within an article of clothing is described. In one embodiment, the communications system is integrated or incorporated into a shoe insole and includes a haptic feedback mechanism, a communications module, a flexible pressure sensor, and a battery. The communications module includes a wireless communications module for wireless communications, a wired interface for wired communications, a microcontroller, and a battery charge controller. The flexible pressure sensor can be actuated by an individual\\'s toe, for example, and communication between two communications nodes can be achieved using coded signals sent by individuals using a combination of long and short presses on the pressure sensor. In response to the presses, wireless communications modules can transmit and receive coded signals based on the presses.

Constraints of nonresponding flows based on cross layers in the networks

Science.gov (United States)

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.

System Architecture and Mobility Management for Mobile Immersive Communications

Directory of Open Access Journals (Sweden)

Mehran Dowlatshahi

2007-01-01

Full Text Available We propose a system design for delivery of immersive communications to mobile wireless devices based on a distributed proxy model. It is demonstrated that this architecture addresses key technical challenges for the delivery of these services, that is, constraints on link capacity and power consumption in mobile devices. However, additional complexity is introduced with respect to application layer mobility management. The paper proposes three possible methods for updating proxy assignments in response to mobility management and compares the performance of these methods.

A communication-theory based view on telemedical communication.

Science.gov (United States)

Schall, Thomas; Roeckelein, Wolfgang; Mohr, Markus; Kampshoff, Joerg; Lange, Tim; Nerlich, Michael

2003-01-01

Communication theory based analysis sheds new light on the use of health telematics. This analysis of structures in electronic medical communication shows communicative structures with special features. Current and evolving telemedical applications are analyzed. The methodology of communicational theory (focusing on linguistic pragmatics) is used to compare it with its conventional counterpart. The semiotic model, the roles of partners, the respective message and their relation are discussed. Channels, sender, addressee, and other structural roles are analyzed for different types of electronic medical communication. The communicative processes are shown as mutual, rational action towards a common goal. The types of communication/texts are analyzed in general. Furthermore the basic communicative structures of medical education via internet are presented with their special features. The analysis shows that electronic medical communication has special features compared to everyday communication: A third participant role often is involved: the patient. Messages often are addressed to an unspecified partner or to an unspecified partner within a group. Addressing in this case is (at least partially) role-based. Communication and message often directly (rather than indirectly) influence actions of the participants. Communication often is heavily regulated including legal implications like liability, and more. The conclusion from the analysis is that the development of telemedical applications so far did not sufficiently take communicative structures into consideration. Based on these results recommendations for future developments of telemedical applications/services are given.

Cross-Layer Energy Optimization for IoT Environments: Technical Advances and Opportunities

Directory of Open Access Journals (Sweden)

Kirshna Kumar

2017-12-01

Full Text Available Energy efficiency is a significant characteristic of battery-run devices such as sensors, RFID and mobile phones. In the present scenario, this is the most prominent requirement that must be served while introducing a communication protocol for an IoT environment. IoT network success and performance enhancement depend heavily on optimization of energy consumption that enhance the lifetime of IoT nodes and the network. In this context, this paper presents a comprehensive review on energy efficiency techniques used in IoT environments. The techniques proposed by researchers have been categorized based on five different layers of the energy architecture of IoT. These five layers are named as sensing, local processing and storage, network/communication, cloud processing and storage, and application. Specifically, the significance of energy efficiency in IoT environments is highlighted. A taxonomy is presented for the classification of related literature on energy efficient techniques in IoT environments. Following the taxonomy, a critical review of literature is performed focusing on major functional models, strengths and weaknesses. Open research challenges related to energy efficiency in IoT are identified as future research directions in the area. The survey should benefit IoT industry practitioners and researchers, in terms of augmenting the understanding of energy efficiency and its IoT-related trends and issues.

Evaluation and Communication: Using a Communication Audit to Evaluate Organizational Communication

Science.gov (United States)

Hogard, Elaine; Ellis, Roger

2006-01-01

This article identifies a surprising dearth of studies that explicitly link communication and evaluation at substantive, theoretical, and methodological levels. A three-fold typology of evaluation studies referring to communication is proposed and examples given. The importance of organizational communication in program delivery is stressed and…

A Cross-Layered Communication Protocol for Load Balancing in Large Scale Multi-sink Wireless Sensor Networks

NARCIS (Netherlands)

Erman-Tüysüz, A.; Mutter, T.; van Hoesel, L.F.W.; Havinga, Paul J.M.

2008-01-01

One of the fundamental operations in sensor networks is convergecast which refers to the communication pattern in which data is collected from a set of sensor nodes and forwarded to a common end-point gateway, namely sink node, in the network. In case of multiple sinks within the network, the total

A Cross-Layered Communication Protocol for Load Balancing in Large Scale Multi-sink Wireless Sensor Networks

NARCIS (Netherlands)

Erman-Tüysüz, A.; Mutter, T.; van Hoesel, L.F.W.; Havinga, Paul J.M.

One of the fundamental operations in sensor networks is convergecast which refers to the communication pattern in which data is collected from a set of sensor nodes and forwarded to a common end-point gateway, namely sink node, in the network. In case of multiple sinks within the network, the total

Science communication as political communication

Science.gov (United States)

Scheufele, Dietram A.

2014-01-01

Scientific debates in modern societies often blur the lines between the science that is being debated and the political, moral, and legal implications that come with its societal applications. This manuscript traces the origins of this phenomenon to professional norms within the scientific discipline and to the nature and complexities of modern science and offers an expanded model of science communication that takes into account the political contexts in which science communication takes place. In a second step, it explores what we know from empirical work in political communication, public opinion research, and communication research about the dynamics that determine how issues are debated and attitudes are formed in political environments. Finally, it discusses how and why it will be increasingly important for science communicators to draw from these different literatures to ensure that the voice of the scientific community is heard in the broader societal debates surrounding science. PMID:25225389

Science communication as political communication.

Science.gov (United States)

Scheufele, Dietram A

2014-09-16

Scientific debates in modern societies often blur the lines between the science that is being debated and the political, moral, and legal implications that come with its societal applications. This manuscript traces the origins of this phenomenon to professional norms within the scientific discipline and to the nature and complexities of modern science and offers an expanded model of science communication that takes into account the political contexts in which science communication takes place. In a second step, it explores what we know from empirical work in political communication, public opinion research, and communication research about the dynamics that determine how issues are debated and attitudes are formed in political environments. Finally, it discusses how and why it will be increasingly important for science communicators to draw from these different literatures to ensure that the voice of the scientific community is heard in the broader societal debates surrounding science.

Unified communications

OpenAIRE

Kravos, Urban

2011-01-01

In the modern business world, communication are becoming more and more complex. As a solution to this problem unified communications occurred. Using a single communication approach unified communications are the integration of various communication technologies (eg, telephony, unified messaging, audio, video and web conferencing and collaboration tools). Unified Messaging, which represents only part of the unified communications means the integration of different non real time communication t...

Evaluation of white matter hyperintensities and retinal fiber layer, ganglion cell layer, inner-plexiform layer, and choroidal layer in migraine patients.

Science.gov (United States)

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 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.

The Dialectics of Communicative and Immanent Critique

Directory of Open Access Journals (Sweden)

Johan Fornäs

2013-11-01

Full Text Available In cultural studies and cultural research, the importance of being critical is often stressed, but it is more rare to scrutinise how such critique is and can be performed. This text discusses different modes of critique, in three main steps. First, a brief review of the history and signifying layers of the concept of critique itself leads up to a late modern communicative concept of critique, linked to the contested relation between critique and tradition, and based on how Paul Ricoeur has interpreted ideology critique and the hermeneutics of suspicion. This communicative mode is contrasted to critical approaches that strive to radically dissociate themselves from others. Second, it is argued that the most powerful sources of critique are to be sought in the inner contradictions of the targeted spheres of social reality rather than applied from the outside. Such immanent – as opposed to transcendent – critique, has been formulated and exercised by Karl Marx, Theodor W. Adorno and Walter Benjamin, among others. The third section sums up the spiral moves of cultural studies as informed by critical hermeneutics: dialectical critique based on communicative and immanent critique must be on the move, never frozen, and may temporarily and locally explore radical and transcendent modes of critique, in ways that have been discussed by Donna Haraway.

Effectiveness evaluation of double-layered satellite network with laser and microwave hybrid links based on fuzzy analytic hierarchy process

Science.gov (United States)

Zhang, Wei; Rao, Qiaomeng

2018-01-01

In order to solve the problem of high speed, large capacity and limited spectrum resources of satellite communication network, a double-layered satellite network with global seamless coverage based on laser and microwave hybrid links is proposed in this paper. By analyzing the characteristics of the double-layered satellite network with laser and microwave hybrid links, an effectiveness evaluation index system for the network is established. And then, the fuzzy analytic hierarchy process, which combines the analytic hierarchy process and the fuzzy comprehensive evaluation theory, is used to evaluate the effectiveness of the double-layered satellite network with laser and microwave hybrid links. Furthermore, the evaluation result of the proposed hybrid link network is obtained by simulation. The effectiveness evaluation process of the proposed double-layered satellite network with laser and microwave hybrid links can help to optimize the design of hybrid link double-layered satellite network and improve the operating efficiency of the satellite system.

Layered-metal-hydroxide nanosheet arrays with controlled nanostructures to assist direct electronic communication at biointerfaces.

Science.gov (United States)

An, Zhe; Lu, Shan; Zhao, Liwei; He, Jing

2011-10-18

In this work, ordered vertical arrays of layered double hydroxide (LDH) nanosheets have been developed to achieve electron transfer (eT) at biointerfaces in electrochemical devices. It is found that tailoring the gap size of LDH nanosheet arrays could significantly promote the eT rate. This research has successfully extended nanomaterials for efficient modifications of electrode surfaces from nanoparticles, nanowires, nanorods, and nanotubes to nanosheets. © 2011 American Chemical Society

Cross-layer combining of adaptive modulation and truncated ARQ under cognitive radio resource requirements

KAUST Repository

Yang, Yuli; Ma, Hao; Aï ssa, Sonia

2012-01-01

In addressing the issue of taking full advantage of the shared spectrum under imposed limitations in a cognitive radio (CR) network, we exploit a cross-layer design for the communications of secondary users (SUs), which combines adaptive modulation and coding (AMC) at the physical layer with truncated automatic repeat request (ARQ) protocol at the data link layer. To achieve high spectral efficiency (SE) while maintaining a target packet loss probability (PLP), switching among different transmission modes is performed to match the time-varying propagation conditions pertaining to the secondary link. Herein, by minimizing the SU's packet error rate (PER) with each transmission mode subject to the spectrum-sharing constraints, we obtain the optimal power allocation at the secondary transmitter (ST) and then derive the probability density function (pdf) of the received SNR at the secondary receiver (SR). Based on these statistics, the SU's packet loss rate and average SE are obtained in closed form, considering transmissions over block-fading channels with different distributions. Our results quantify the relation between the performance of a secondary link exploiting the cross-layer-designed adaptive transmission and the interference inflicted on the primary user (PU) in CR networks. © 1967-2012 IEEE.

Enhancing performance of next generation FSO communication systems using soft computing-based predictions.

Science.gov (United States)

Kazaura, Kamugisha; Omae, Kazunori; Suzuki, Toshiji; Matsumoto, Mitsuji; Mutafungwa, Edward; Korhonen, Timo O; Murakami, Tadaaki; Takahashi, Koichi; Matsumoto, Hideki; Wakamori, Kazuhiko; Arimoto, Yoshinori

2006-06-12

The deterioration and deformation of a free-space optical beam wave-front as it propagates through the atmosphere can reduce the link availability and may introduce burst errors thus degrading the performance of the system. We investigate the suitability of utilizing soft-computing (SC) based tools for improving performance of free-space optical (FSO) communications systems. The SC based tools are used for the prediction of key parameters of a FSO communications system. Measured data collected from an experimental FSO communication system is used as training and testing data for a proposed multi-layer neural network predictor (MNNP) used to predict future parameter values. The predicted parameters are essential for reducing transmission errors by improving the antenna's accuracy of tracking data beams. This is particularly essential for periods considered to be of strong atmospheric turbulence. The parameter values predicted using the proposed tool show acceptable conformity with original measurements.

"We definitely need an audience": experiences of Twitter, Twitter networks and tweet content in adults with severe communication disabilities who use augmentative and alternative communication (AAC).

Science.gov (United States)

Hemsley, Bronwyn; Dann, Stephen; Palmer, Stuart; Allan, Meredith; Balandin, Susan

2015-01-01

The aim of this study was to investigate the Twitter experiences of adults with severe communication disabilities who use augmentative and alternative communication (AAC) to inform Twitter training and further research on the use of Twitter in populations with communication disabilities. This mixed methods research included five adults with severe communication disabilities who use AAC. It combined (a) quantitative analysis of Twitter networks and (b) manual coding of tweets with (c) narrative interviews with participants on their Twitter experiences and results. The five participants who used AAC and Twitter were diverse in their patterns and experiences of using Twitter. Twitter networks reflected interaction with a close-knit network of people rather than with the broader publics on Twitter. Conversational, Broadcast and Pass Along tweets featured most prominently, with limited use of News or Social Presence tweets. Tweets appeared mostly within each participant's micro- or meso-structural layers of Twitter. People who use AAC report positive experiences in using Twitter. Obtaining help in Twitter, and engaging in hashtag communities facilitated higher frequency of tweets and establishment of Twitter networks. Results reflected an inter-connection of participant Twitter networks that might form part of a larger as yet unexplored emergent community of people who use AAC in Twitter.

Layer-dependent band alignment and work function of few-layer phosphorene.

Science.gov (United States)

Cai, Yongqing; Zhang, Gang; Zhang, Yong-Wei

2014-10-20

Using first-principles calculations, we study the electronic properties of few-layer phosphorene focusing on layer-dependent behavior of band gap, work function band alignment and carrier effective mass. It is found that few-layer phosphorene shows a robust direct band gap character, and its band gap decreases with the number of layers following a power law. The work function decreases rapidly from monolayer (5.16 eV) to trilayer (4.56 eV), and then slowly upon further increasing the layer number. Compared to monolayer phosphorene, there is a drastic decrease of hole effective mass along the ridge (zigzag) direction for bilayer phosphorene, indicating a strong interlayer coupling and screening effect. Our study suggests that 1). Few-layer phosphorene with a layer-dependent band gap and a robust direct band gap character is promising for efficient solar energy harvest. 2). Few-layer phosphorene outperforms monolayer counterpart in terms of a lighter carrier effective mass, a higher carrier density and a weaker scattering due to enhanced screening. 3). The layer-dependent band edges and work functions of few-layer phosphorene allow for modification of Schottky barrier with enhanced carrier injection efficiency. It is expected that few-layer phosphorene will present abundant opportunities for a plethora of new electronic applications.

Adjacent Vehicle Number-Triggered Adaptive Transmission for V2V Communications.

Science.gov (United States)

Wei, Yiqiao; Chen, Jingjun; Hwang, Seung-Hoon

2018-03-02

For vehicle-to-vehicle (V2V) communication, such issues as continuity and reliability still have to be solved. Specifically, it is necessary to consider a more scalable physical layer due to the high-speed mobility of vehicles and the complex channel environment. Adaptive transmission has been adapted in channel-dependent scheduling. However, it has been neglected with regards to the physical topology changes in the vehicle network. In this paper, we propose a physical topology-triggered adaptive transmission scheme which adjusts the data rate between vehicles according to the number of connectable vehicles nearby. Also, we investigate the performance of the proposed method using computer simulations and compare it with the conventional methods. The numerical results show that the proposed method can provide more continuous and reliable data transmission for V2V communications.

Natural melanin composites by layer-by-layer assembly

Science.gov (United States)

Eom, Taesik; Shim, Bong Sub

2015-04-01

Melanin is an electrically conductive and biocompatible material, because their conjugated backbone structures provide conducting pathways from human skin, eyes, brain, and beyond. So there is a potential of using as materials for the neural interfaces and the implantable devices. Extracted from Sepia officinalis ink, our natural melanin was uniformly dispersed in mostly polar solvents such as water and alcohols. Then, the dispersed melanin was further fabricated to nano-thin layered composites by the layer-by-layer (LBL) assembly technique. Combined with polyvinyl alcohol (PVA), the melanin nanoparticles behave as an LBL counterpart to from finely tuned nanostructured films. The LBL process can adjust the smart performances of the composites by varying the layering conditions and sandwich thickness. We further demonstrated the melanin loading degree of stacked layers, combination nanostructures, electrical properties, and biocompatibility of the resulting composites by UV-vis spectrophotometer, scanning electron microscope (SEM), multimeter, and in-vitro cell test of PC12, respectively.

Internal interface: I/O communication with FPGA circuits and hardware description standard for applications in HEP and FEL electronics ver. 1.0

International Nuclear Information System (INIS)

Pozniak, K.T.

2005-01-01

The work describes hardware layer of the universal, parameterized communication interface for application in the FPGA chips. The interface is called in this work as the ''Internal Interface'' or in short the ''II''. The paper shows how to automatically create the address and data space, according to the user declarations. The methods to standardize the I/O communication with FPGA chips are described. The communication uses library functions and standardized, parametric components in VHDL. Theoretical background and technical description of the Internal Interface are illustrated with a few easy examples of simple interfaces. (orig.)

CSR communication

DEFF Research Database (Denmark)

Golob, Ursa; Podnar, Klement; Elving, Wim

2013-01-01

Purpose – This paper aims to introduce the special issue on CSR communication attached to the First International CSR Communication Conference held in Amsterdam in October 2011. The aim of the introduction is also to review CSR communication papers published in scholarly journals in order to make...... a summary of the state of CSR communication knowledge. Design/methodology/approach – The existing literature on CSR communication was approached via systematic review. with a combination of conventional and summative qualitative content analysis. The final dataset contained 90 papers from two main business...... communications. The most important outlets for CSR communication-related topics are Journal of Business Ethics and Corporate Communications: An International Journal. Originality/value – This paper represents the first attempt to perform a systematic and comprehensive overview of CSR communication papers...

Strategizing Communication

DEFF Research Database (Denmark)

Gulbrandsen, Ib Tunby; Just, Sine Nørholm

beyond, but not past instrumental, rational plans in order to become better able to understand and manage the concrete, incremental practices and contexts in which communication becomes strategic. Thus, we argue that although strategic communicators do (and should) make plans, a plan in itself does...... of the specific communicative disciplines and practices employed by the organization and/or its individual members, be they marketing, public relations, corporate communication, branding, public affairs or social advocacy. In all cases, strategic communicators do well to focus more on the process of communicating...... for understanding and managing strategic communication processes....

Streetlight Control System Based on Wireless Communication over DALI Protocol

Directory of Open Access Journals (Sweden)

Francisco José Bellido-Outeiriño

2016-04-01

Full Text Available Public lighting represents a large part of the energy consumption of towns and cities. Efficient management of public lighting can entail significant energy savings. This work presents a smart system for managing public lighting networks based on wireless communication and the DALI protocol. Wireless communication entails significant economic savings, as there is no need to install new wiring and visual impacts and damage to the facades of historical buildings in city centers are avoided. The DALI protocol uses bidirectional communication with the ballast, which allows its status to be controlled and monitored at all times. The novelty of this work is that it tackles all aspects related to the management of public lighting: a standard protocol, DALI, was selected to control the ballast, a wireless node based on the IEEE 802.15.4 standard with a DALI interface was designed, a network layer that considers the topology of the lighting network has been developed, and lastly, some user-friendly applications for the control and maintenance of the system by the technical crews of the different towns and cities have been developed.

Business communication and globalized English: recent definitions and applications of a concept across the corporate world

Directory of Open Access Journals (Sweden)

Fee-Alexandra HAASE

2014-10-01

Full Text Available This article approaches ‘business communication’ as a multi-layered economic phenomenon of the corporate society of the globalized business world. In academic education systems and in the business world under the term ‘business communication’ various definitions exist, which are applied across the fields of academic studies and in the business world. After the comparison of definitions of ‘business communication’, we demonstrate the various layers of business communication in the contemporary corporate world based upon a model of the corporate world and these cases using examples of companies implementing ‘business communication’ into their corporate structure.

"Audio-visuel Integre" et Communication(s) ("Integrated Audiovisual" and Communication)

Science.gov (United States)

Moirand, Sophie

1974-01-01

This article examines the usefullness of the audiovisual method in teaching communication competence, and calls for research in audiovisual methods as well as in communication theory for improvement in these areas. (Text is in French.) (AM)

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

Science.gov (United States)

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

1995-11-01

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

Low frequency noise in asymmetric double barrier magnetic tunnel junctions with a top thin MgO layer

International Nuclear Information System (INIS)

Guo Hui-Qiang; Tang Wei-Yue; Liu Liang; Wei Jian; Li Da-Lai; Feng Jia-Feng; Han Xiu-Feng

2015-01-01

Low frequency noise has been investigated at room temperature for asymmetric double barrier magnetic tunnel junctions (DBMTJs), where the coupling between the top and middle CoFeB layers is antiferromagnetic with a 0.8-nm thin top MgO barrier of the CoFeB/MgO/CoFe/CoFeB/MgO/CoFeB DBMTJ. At enough large bias, 1/f noise dominates the voltage noise power spectra in the low frequency region, and is conventionally characterized by the Hooge parameter α mag . With increasing external field, the top and bottom ferromagnetic layers are aligned by the field, and then the middle free layer rotates from antiparallel state (antiferromagnetic coupling between top and middle ferromagnetic layers) to parallel state. In this rotation process α mag and magnetoresistance-sensitivity-product show a linear dependence, consistent with the fluctuation dissipation relation. With the magnetic field applied at different angles (θ) to the easy axis of the free layer, the linear dependence persists while the intercept of the linear fit satisfies a cos(θ) dependence, similar to that for the magnetoresistance, suggesting intrinsic relation between magnetic losses and magnetoresistance. (rapid communication)

High Performance Nano-Constituent Buffer Layer Thin Films to Enable Low Cost Integrated On-the-Move Communications Systems

National Research Council Canada - National Science Library

Cole, M. W; Nothwang, W. D; Hubbard, C; Ngo, E; Hirsch, S

2004-01-01

.... Utilizing a coplanar device design we successfully designed, fabricated, characterized, and optimized a high performance Ta2O5 thin film passive buffer layer on Si substrates, which will allow...

An application-layer based centralized information access control for VPN

Institute of Scientific and Technical Information of China (English)

OUYANG Kai; ZHOU Jing-li; XIA Tao; YU Sheng-sheng

2006-01-01

With the rapid development of Virtual Private Network (VPN), many companies and organizations use VPN to implement their private communication. Traditionally, VPN uses security protocols to protect the confidentiality of data, the message integrity and the endpoint authentication. One core technique of VPN is tunneling, by which clients can access the internal servers traversing VPN. However, the tunneling technique also introduces a concealed security hole. It is possible that ifone vicious user can establish tunneling by the VPN server, he can compromise the internal servers behind the VPN server. So this paper presents a novel Application-layer based Centralized Information Access Control (ACIAC) for VPN to solve this problem.To implement an efficient, flexible and multi-decision access control model, we present two key techniques to ACIAC-the centralized management mechanism and the stream-based access control. Firstly, we implement the information center and the constraints/events center for ACIAC. By the two centers, we can provide an abstract access control mechanism, and the material access control can be decided dynamically by the ACIAC's constraint/event mechanism. Then we logically classify the VPN communication traffic into the access stream and the data stream so that we can tightly couple the features of VPN communication with the access control model. We also provide the design of our ACIAC prototype in this paper.

Karl Marx & Communication @ 200: Towards a Marxian Theory of Communication

Directory of Open Access Journals (Sweden)

Christian Fuchs

2018-05-01

Full Text Available This contribution takes Marx’s bicentenary as occasion for reflecting on foundations of a Marxian theory of communication. It aims to show that Marx provides a consistent account as foundation for a critical, dialectical theory of communication. The article first discusses the relationship of communication and materialism in order to ground a communicative materialism that avoids the dualist assumption that communication is a superstructure erected on a material base. Second, the paper provides an overview of how Marx’s approach helps us to understand the role of the means of communication and communicative labour in capitalism. Third, it conceives of ideology as a form of fetishised communication and fetishism as ideological communication. Given that communicative capitalism is a significant dimension of contemporary society, it is about time to develop a Marxian theory of communication.

Layer-by-layer strippable Ag multilayer films fabricated by modular assembly.

Science.gov (United States)

Li, Yan; Chen, Xiaoyan; Li, Qianqian; Song, Kai; Wang, Shihui; Chen, Xiaoyan; Zhang, Kai; Fu, Yu; Jiao, Yong-Hua; Sun, Ting; Liu, Fu-Chun; Han, En-Hou

2014-01-21

We have developed a new method to fabricate multilayer films, which uses prepared thin films as modular blocks and transfer as operation mode to build up multilayer structures. In order to distinguish it from the in situ fabrication manner, this method is called modular assembly in this study. On the basis of such concept, we have fabricated a multilayer film using the silver mirror film as the modular block and poly(lactic acid) as the transfer tool. Due to the special double-layer structure of the silver mirror film, the resulting multilayer film had a well-defined stratified architecture with alternate porous/compact layers. As a consequence of the distinct structure, the interaction between the adjacent layers was so weak that the multilayer film could be layer-by-layer stripped. In addition, the top layer in the film could provide an effective protection on the morphology and surface property of the underlying layers. This suggests that if the surface of the film was deteriorated, the top layer could be peeled off and the freshly exposed surface would still maintain the original function. The successful preparation of the layer-by-layer strippable silver multilayer demonstrates that modular assembly is a feasible and effective method to build up multilayer films capable of creating novel and attractive micro/nanostructures, having great potential in the fabrication of nanodevices and coatings.

A COTS RF Optical Software Defined Radio for the Integrated Radio and Optical Communications Test Bed

Science.gov (United States)

Nappier, Jennifer M.; Zeleznikar, Daniel J.; Wroblewski, Adam C.; Tokars, Roger P.; Schoenholz, Bryan L.; Lantz, Nicholas C.

2016-01-01

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration (NASA) is investigating the merits of a hybrid radio frequency (RF) and optical communication system for deep space missions. In an effort to demonstrate the feasibility and advantages of a hybrid RFOptical software defined radio (SDR), a laboratory prototype was assembled from primarily commercial-off-the-shelf (COTS) hardware components. This COTS platform has been used to demonstrate simultaneous transmission of the radio and optical communications waveforms through to the physical layer (telescope and antenna). This paper details the hardware and software used in the platform and various measures of its performance. A laboratory optical receiver platform has also been assembled in order to demonstrate hybrid free space links in combination with the transmitter.

A COTS RF/Optical Software Defined Radio for the Integrated Radio and Optical Communications Test Bed

Science.gov (United States)

Nappier, Jennifer M.; Zeleznikar, Daniel J.; Wroblewski, Adam C.; Tokars, Roger P.; Schoenholz, Bryan L.; Lantz, Nicholas C.

2017-01-01

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration (NASA) is investigating the merits of a hybrid radio frequency (RF) and optical communication system for deep space missions. In an effort to demonstrate the feasibility and advantages of a hybrid RF/Optical software defined radio (SDR), a laboratory prototype was assembled from primarily commercial-off-the-shelf (COTS) hardware components. This COTS platform has been used to demonstrate simultaneous transmission of the radio and optical communications waveforms through to the physical layer (telescope and antenna). This paper details the hardware and software used in the platform and various measures of its performance. A laboratory optical receiver platform has also been assembled in order to demonstrate hybrid free space links in combination with the transmitter.

Resonant communicators, effective communicators. Communicator’s flow and credibility

Directory of Open Access Journals (Sweden)

Irene García-Ureta, Ph.D

2012-01-01

Full Text Available Communication studies have been integrating the latest developments in cognitive sciences and acknowledging the importance of understanding the subjective processes involved in communication. This article argues that communication studies should also take into account the psychology of the communicator. This article presents the theoretical basis and the results of a training programme designed for audiovisual communicators. The programme is based on the theories of self-efficacy and flow and seeks to improve students’ communication competencies through the use of presentation techniques and psychological skills to tackle communication apprehension. The programme involves an active methodology that is based on modelling, visualisation, immediate feedback and positive reinforcement. A repeated-measures ANOVA shows that the programme successfully decreases the level of communication apprehension, improves the perceived self-efficacy, improves the psychological state needed to perform better in front of the cameras (flow, and improves students’ communication skills. A path analysis proved that the perceived self-efficacy and anxiety levels predict the level of flow during the communication act. At the end of the training programme, those who experienced higher levels of flow and enjoyment during the communication task achieved higher quality levels in their communication exercise. It is concluded that the concepts of self-efficacy and flow facilitate advancing in the understanding of the factors that determine a communicator’s credibility and ability to connect with the audience.

The double layers in the plasma sheet boundary layer during magnetic reconnection

Science.gov (United States)

Guo, J.; Yu, B.

2014-11-01

We studied the evolutions of double layers which appear after the magnetic reconnection through two-dimensional electromagnetic particle-in-cell simulation. The simulation results show that the double layers are formed in the plasma sheet boundary layer after magnetic reconnection. At first, the double layers which have unipolar structures are formed. And then the double layers turn into bipolar structures, which will couple with another new weak bipolar structure. Thus a new double layer or tripolar structure comes into being. The double layers found in our work are about several ten Debye lengths, which accords with the observation results. It is suggested that the electron beam formed during the magnetic reconnection is responsible for the production of the double layers.

Periodic materials-based vibration attenuation in layered foundations: experimental validation

International Nuclear Information System (INIS)

Xiang, H J; Shi, Z F; Wang, S J; Mo, Y L

2012-01-01

Guided by the recent advances in solid-state research in periodic materials, a new type of layered periodic foundation consisting of concrete and rubber layers is experimentally investigated in this paper. The distinct feature of this new foundation is its frequency band gaps. When the frequency contents of a wave fall within the range of the frequency band gaps, the wave, and hence its energy, will be weakened or cannot propagate through the foundation, so the foundation itself can serve as a vibration isolator. Using the theory of elastodynamics and the Bloch–Floquet theorem, the mechanism of band gaps in periodic composites is presented, and a finite element model is built to show the isolation characteristic of a finite dimensional periodic foundation. Based on these analytical results, moreover, a scaled model frame and a periodic foundation were fabricated and shake table tests of the frame on the periodic foundation were performed. Ambient, strong and harmonic vibration attenuations are found when the exciting frequencies fall into the band gaps. (fast track communication)

Communicating geological hazards: assisting geoscientists in communication skills

Science.gov (United States)

Liverman, D. G. E.

2009-04-01

Communication is important in all aspects of the geosciences but is more prominent in the area of geological hazards, as the main audience for scientific information often lacks a geoscience background; and because the implications of not communicating results effectively can be very serious. Geoscientists working in the hazards area face particular challenges in communicating the concepts of risk, probability and uncertainty. Barriers to effective communication of geoscience include the complex language used by geoscientists, restriction of dissemination of results to traditional scientific media, identification of the target audience, inability to tailor products to a variety of audiences, and lack of institutional support for communication efforts. Geoscientists who work in the area of natural hazards need training in risk communication, media relations, and communicating to non-technical audiences. Institutions need to support the efforts of geoscientists in communicating their results through providing communications training; ensuring access to communications professionals; rewarding efforts to engage the public; and devoting sufficient staff and budget to the effort of disseminating results. Geoscientists themselves have to make efforts to change attitudes towards social science, and to become involved in decision making at a community level. The International Union of Geological Sciences Commission for "Geoscience for Environmental Management" established a working group to deal with these issues. This group is holding workshops, publishing collections of papers, and is looking at other means to aid geoscientists in addressing these problems.

Novel Reduced-Feedback Wireless Communication Systems

KAUST Repository

Shaqfeh, Mohammad Obaidah

2011-11-20

including fairness in resources distribution across the active terminals and distributed processing at the MAC layer level. In addition our scheme operates close to the upper capacity limits of achievable transmission rates over wireless links. We have also proposed another hybrid scheme that enables adjusting the feedback load flexibly based on rates requirements. We are currently investigating other novel ideas to design reduced-feedback communication systems.

The Plasmasphere Boundary Layer

Directory of Open Access Journals (Sweden)

D. L. Carpenter

2004-12-01

Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere.

Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

The Plasmasphere Boundary Layer

Directory of Open Access Journals (Sweden)

D. L. Carpenter

2004-12-01

Full Text Available As an inner magnetospheric phenomenon the plasmapause region is of interest for a number of reasons, one being the occurrence there of geophysically important interactions between the plasmas of the hot plasma sheet and of the cool plasmasphere. There is a need for a conceptual framework within which to examine and discuss these interactions and their consequences, and we therefore suggest that the plasmapause region be called the Plasmasphere Boundary Layer, or PBL. Such a term has been slow to emerge because of the complexity and variability of the plasma populations that can exist near the plasmapause and because of the variety of criteria used to identify the plasmapause in experimental data. Furthermore, and quite importantly in our view, a substantial obstacle to the consideration of the plasmapause region as a boundary layer has been the longstanding tendency of textbooks on space physics to limit introductory material on the plasmapause phenomenon to zeroth order descriptions in terms of ideal MHD theory, thus implying that the plasmasphere is relatively well understood. A textbook may introduce the concept of shielding of the inner magnetosphere from perturbing convection electric fields, but attention is not usually paid to the variety of physical processes reported to occur in the PBL, such as heating, instabilities, and fast longitudinal flows, processes which must play roles in plasmasphere dynamics in concert with the flow regimes associated with the major dynamo sources of electric fields. We believe that through the use of the PBL concept in future textbook discussions of the plasmasphere and in scientific communications, much progress can be made on longstanding questions about the physics involved in the formation of the plasmapause and in the cycles of erosion and recovery of the plasmasphere. Key words. Magnetospheric physics (plasmasphere; plasma convection; MHD waves and instabilities

Data communications

International Nuclear Information System (INIS)

Preckshot, G.G.

1993-08-01

The purpose of this paper is to recommend regulatory guidance for reviewers examining computer communication systems used in nuclear power plants. The recommendations cover three areas important to these communications systems: system design, communication protocols, and communication media. The first area, system design, considers three aspects of system design--questions about architecture, specific risky design elements or omissions to look for in designs being reviewed, and recommendations for multiplexed data communication systems used in safety systems. The second area reviews pertinent aspects of communication protocol design and makes recommendations for newly designed protocols or the selection of existing protocols for safety system, information display, and non-safety control system use. The third area covers communication media selection, which differs significantly from traditional wire and cable. The recommendations for communication media extend or enhance the concerns of published IEEE standards about three subjects: data rate, imported hazards and maintainability

Adjacent Vehicle Number-Triggered Adaptive Transmission for V2V Communications

Science.gov (United States)

Wei, Yiqiao; Chen, Jingjun

2018-01-01

For vehicle-to-vehicle (V2V) communication, such issues as continuity and reliability still have to be solved. Specifically, it is necessary to consider a more scalable physical layer due to the high-speed mobility of vehicles and the complex channel environment. Adaptive transmission has been adapted in channel-dependent scheduling. However, it has been neglected with regards to the physical topology changes in the vehicle network. In this paper, we propose a physical topology-triggered adaptive transmission scheme which adjusts the data rate between vehicles according to the number of connectable vehicles nearby. Also, we investigate the performance of the proposed method using computer simulations and compare it with the conventional methods. The numerical results show that the proposed method can provide more continuous and reliable data transmission for V2V communications. PMID:29498646

Resilient Communication: A New Crisis Communication Strategy for Homeland Security

Science.gov (United States)

2012-03-01

communication theory. Author, Timothy Coombs , in Ongoing Crisis Communication , discusses the need for a crisis management 10 plan to prepare for potential... COMMUNICATION : A NEW CRISIS COMMUNICATION STRATEGY FOR HOMELAND SECURITY by Sharon L. Watson March 2012 Thesis Advisor: Christopher Bellavita...REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Resilient Communication : A New Crisis Communication

The Impact of a Group Communication Course on Veterinary Medical Students' Perceptions of Communication Competence and Communication Apprehension.

Science.gov (United States)

Kedrowicz, April A

2016-01-01

This paper explores the impact of a group communication course on veterinary medical students' perceptions of communication competence and communication anxiety. Students enrolled in the Group Communication in Veterinary Medicine course completed the Personal Report of Communication Apprehension and the Communicative Competence Scale at the beginning (Time 1) and end (Time 2) of the semester. Results show that first-year veterinary students' self-perceptions of communication competence increased and their self-reported levels of communication apprehension decreased across multiple contexts from Time 1 to Time 2. This research provides support for experiential communication training fostering skill development and confidence.

A Reinforcement Learning Approach to Call Admission Control in HAPS Communication System

Directory of Open Access Journals (Sweden)

Ni Shu Yan

2017-01-01

Full Text Available The large changing of link capacity and number of users caused by the movement of both platform and users in communication system based on high altitude platform station (HAPS will resulting in high dropping rate of handover and reduce resource utilization. In order to solve these problems, this paper proposes an adaptive call admission control strategy based on reinforcement learning approach. The goal of this strategy is to maximize long-term gains of system, with the introduction of cross-layer interaction and the service downgraded. In order to access different traffics adaptively, the access utility of handover traffics and new call traffics is designed in different state of communication system. Numerical simulation result shows that the proposed call admission control strategy can enhance bandwidth resource utilization and the performances of handover traffics.

Capacity Estimation and Near-Capacity Achieving Techniques for Digitally Modulated Communication Systems

DEFF Research Database (Denmark)

Yankov, Metodi Plamenov

investigation will include linear interference channels of high dimensionality (such as multiple-input multiple-output), and the non-linear optical fiber channel, which has been gathering more and more attention from the information theory community in recent years. In both cases novel CCC estimates and lower......This thesis studies potential improvements that can be made to the current data rates of digital communication systems. The physical layer of the system will be investigated in band-limited scenarios, where high spectral efficiency is necessary in order to meet the ever-growing data rate demand....... Several issues are tackled, both with theoretical and more practical aspects. The theoretical part is mainly concerned with estimating the constellation constrained capacity (CCC) of channels with discrete input, which is an inherent property of digital communication systems. The channels under...

Design of the HELICS High-Performance Transmission-Distribution-Communication-Market Co-Simulation Framework

Energy Technology Data Exchange (ETDEWEB)

Palmintier, Bryan S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Krishnamurthy, Dheepak [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Top, Philip [Lawrence Livermore National Laboratories; Smith, Steve [Lawrence Livermore National Laboratories; Daily, Jeff [Pacific Northwest National Laboratory; Fuller, Jason [Pacific Northwest National Laboratory

2017-10-12

This paper describes the design rationale for a new cyber-physical-energy co-simulation framework for electric power systems. This new framework will support very large-scale (100,000+ federates) co-simulations with off-the-shelf power-systems, communication, and end-use models. Other key features include cross-platform operating system support, integration of both event-driven (e.g. packetized communication) and time-series (e.g. power flow) simulation, and the ability to co-iterate among federates to ensure model convergence at each time step. After describing requirements, we begin by evaluating existing co-simulation frameworks, including HLA and FMI, and conclude that none provide the required features. Then we describe the design for the new layered co-simulation architecture.

Internal interface: I/O communication with FPGA circuits and hardware description standard for applications in HEP and FEL electronics ver. 1.0

Energy Technology Data Exchange (ETDEWEB)

Pozniak, K.T. [Warsaw Univ. of Technology (Poland). Inst. of Electronic Systems ELHEP Laboratory

2005-07-01

The work describes hardware layer of the universal, parameterized communication interface for application in the FPGA chips. The interface is called in this work as the ''Internal Interface'' or in short the ''II''. The paper shows how to automatically create the address and data space, according to the user declarations. The methods to standardize the I/O communication with FPGA chips are described. The communication uses library functions and standardized, parametric components in VHDL. Theoretical background and technical description of the Internal Interface are illustrated with a few easy examples of simple interfaces. (orig.)

Remote sensing and skywave digital communication from antarctica.

Science.gov (United States)

Bergadà, Pau; Deumal, Marc; Vilella, Carles; Regué, Joan R; Altadill, David; Marsal, Santi

2009-01-01

This paper presents an overview of the research activities undertaken by La Salle and the Ebro Observatory in the field of remote sensing. On 2003 we started a research project with two main objectives: implement a long-haul oblique ionospheric sounder and transmit the data from remote sensors located at the Spanish Antarctic station Juan Carlos I to Spain. The paper focuses on a study of feasibility of two possible physical layer candidates for the skywave link between both points. A DS-SS based solution and an OFDM based solution are considered to achieve a reliable low-power low-rate communication system between Antarctica and Spain.

Cross-layer combining of adaptive modulation and truncated ARQ under cognitive radio resource requirements

KAUST Repository

Yang, Yuli

2012-11-01

In addressing the issue of taking full advantage of the shared spectrum under imposed limitations in a cognitive radio (CR) network, we exploit a cross-layer design for the communications of secondary users (SUs), which combines adaptive modulation and coding (AMC) at the physical layer with truncated automatic repeat request (ARQ) protocol at the data link layer. To achieve high spectral efficiency (SE) while maintaining a target packet loss probability (PLP), switching among different transmission modes is performed to match the time-varying propagation conditions pertaining to the secondary link. Herein, by minimizing the SU\\'s packet error rate (PER) with each transmission mode subject to the spectrum-sharing constraints, we obtain the optimal power allocation at the secondary transmitter (ST) and then derive the probability density function (pdf) of the received SNR at the secondary receiver (SR). Based on these statistics, the SU\\'s packet loss rate and average SE are obtained in closed form, considering transmissions over block-fading channels with different distributions. Our results quantify the relation between the performance of a secondary link exploiting the cross-layer-designed adaptive transmission and the interference inflicted on the primary user (PU) in CR networks. © 1967-2012 IEEE.

Application of a mixture of soils to create a stable layer of support on the slope in ponds waterproofed with geo membranes. Application to a specific case in the reservoir Conseller Jose Ramon Garcia Anton in Elche (Alicante)

International Nuclear Information System (INIS)

Ferran Gozalvez, F. J.; Ferrer Gisbert, C.; Redon Santafe, M.; Perez Sanchez, M.; Torregrosa Solar, J. S.; Zapata Raboso, F. J.; Sanchez Romero, F. J.

2014-01-01

This text present the experience developed in a reservoir in Elche (Alicante). This communication explains the importance of the layer of support to prevent the punching. This phenomenon can occur in a reservoir that has a deficient layer of support. Also, the paper describes the requirements to be met by the support layer to perform its function. (Author)

FPGA-based GEM detector signal acquisition for SXR spectroscopy system

Science.gov (United States)

Wojenski, A.; Pozniak, K. T.; Kasprowicz, G.; Kolasinski, P.; Krawczyk, R.; Zabolotny, W.; Chernyshova, M.; Czarski, T.; Malinowski, K.

2016-11-01

The presented work is related to the Gas Electron Multiplier (GEM) detector soft X-ray spectroscopy system for tokamak applications. The used GEM detector has one-dimensional, 128 channel readout structure. The channels are connected to the radiation-hard electronics with configurable analog stage and fast ADCs, supporting speeds of 125 MSPS for each channel. The digitalized data is sent directly to the FPGAs using fast serial links. The preprocessing algorithms are implemented in the FPGAs, with the data buffering made in the on-board 2Gb DDR3 memory chips. After the algorithmic stage, the data is sent to the Intel Xeon-based PC for further postprocessing using PCI-Express link Gen 2. For connection of multiple FPGAs, PCI-Express switch 8-to-1 was designed. The whole system can support up to 2048 analog channels. The scope of the work is an FPGA-based implementation of the recorder of the raw signal from GEM detector. Since the system will work in a very challenging environment (neutron radiation, intense electro-magnetic fields), the registered signals from the GEM detector can be corrupted. In the case of the very intense hot plasma radiation (e.g. laser generated plasma), the registered signals can overlap. Therefore, it is valuable to register the raw signals from the GEM detector with high number of events during soft X-ray radiation. The signal analysis will have the direct impact on the implementation of photon energy computation algorithms. As the result, the system will produce energy spectra and topological distribution of soft X-ray radiation. The advanced software was developed in order to perform complex system startup and monitoring of hardware units. Using the array of two one-dimensional GEM detectors it will be possible to perform tomographic reconstruction of plasma impurities radiation in the SXR region.

Layer-by-layer assembled biopolymer microcapsule with separate layer cavities generated by gas-liquid microfluidic approach.

Science.gov (United States)

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.

Scientific communication

Directory of Open Access Journals (Sweden)

Aleksander Kobylarek

2017-09-01

Full Text Available The article tackles the problem of models of communication in science. The formal division of communication processes into oral and written does not resolve the problem of attitude. The author defines successful communication as a win-win game, based on the respect and equality of the partners, regardless of their position in the world of science. The core characteristics of the process of scientific communication are indicated , such as openness, fairness, support, and creation. The task of creating the right atmosphere for science communication belongs to moderators, who should not allow privilege and differentiation of position to affect scientific communication processes.

Understanding and improving communication processes in an increasingly multicultural aged care workforce.

Science.gov (United States)

Nichols, Pam; Horner, Barbara; Fyfe, Katrina

2015-01-01

This study explored how culture shapes relationships in aged care and the extent to which the residential aged care sector supports a cohesive multicultural workforce. An exploratory methodology utilising semi-structured questionnaires collected data from 58 participants comprising: staff who provide direct care to residents; managers; and family members from six residential care facilities in Perth, Western Australia. Communication issues emerged as an over-arching theme, and included interpersonal communication, the effect of cultural norms on communication and the impact of informal and formal workplace policies relating to spoken and written language. Sixty percent of participants from a culturally and linguistically diverse (CaLD) background had experienced negative reactions from residents with dementia, linked to visible cultural difference. They used a range of coping strategies including ignoring, resilience and avoidance in such situations. CaLD participants also reported prejudicial treatment from non-CaLD staff. The findings highlight the need for organisations to incorporate explicit processes which address the multiple layers of influence on cross cultural communication: internalised beliefs and values; moderating effects of education, experience and social circumstance; and factors external to the individuals, including workplace culture and the broader political economy, to develop a cohesive multicultural workplace. Copyright © 2015. Published by Elsevier Inc.

COMMUNICATIVE CULTURE AND THE ROLE OF PHATIC FUNCTION IN INTERPERSONAL COMMUNICATION

Directory of Open Access Journals (Sweden)

Kosova Kristina Igorevna

2015-06-01

Full Text Available The article analyses a language function which helps to personalize and control communication arranging it in accordance with communicative norms and rituals. The choice of forms of interpersonal communication is regulated by norms and motivated by conditions of communicative behavior. Interpersonal communication peculiarities are connected in particular with the forms of indirect communication implementing the phatic language function. Phatic communication is viewed as a special form of interpersonal communication which is not connected with the quality of information transfer and which is targeted at regulating interpersonal relations. With the help of special verbal means the specific cause of communication, which is the control of communication arrangement, is implemented. Phatic utterances provide the success of informative function implementation in the future. The article also describes the notion of communicative culture. Standards of communicative culture are connected with the systematization of communication forms and rules in their relation to various communicative functions of the language, phatic function in particular, and national and cultural characteristics of their implementation in speech. Typical cases of contact making and contact maintaining are part of communicative culture's sphere. They are the most important means of regulating interpersonal relations. Representatives of a certain communicative culture know common rules which normalize their verbal behavior and dictate the necessity or lack of necessity to start the interaction. Interpersonal behavior is based on norms of communicative culture which can be defined as loose norms of communication building correlated with speech forms and targeted at people's behavior. It happens in a familiar ethnocultural environment and requires knowledge of phatic communication norms. Phatic communication requires specific consideration since success and efficiency of interpersonal

Design and Development of Layered Security: Future Enhancements and Directions in Transmission

Science.gov (United States)

Shahzad, Aamir; Lee, Malrey; Kim, Suntae; Kim, Kangmin; Choi, Jae-Young; Cho, Younghwa; Lee, Keun-Kwang

2016-01-01

Today, security is a prominent issue when any type of communication is being undertaken. Like traditional networks, supervisory control and data acquisition (SCADA) systems suffer from a number of vulnerabilities. Numerous end-to-end security mechanisms have been proposed for the resolution of SCADA-system security issues, but due to insecure real-time protocol use and the reliance upon open protocols during Internet-based communication, these SCADA systems can still be compromised by security challenges. This study reviews the security challenges and issues that are commonly raised during SCADA/protocol transmissions and proposes a secure distributed-network protocol version 3 (DNP3) design, and the implementation of the security solution using a cryptography mechanism. Due to the insecurities found within SCADA protocols, the new development consists of a DNP3 protocol that has been designed as a part of the SCADA system, and the cryptographically derived security is deployed within the application layer as a part of the DNP3 stack. PMID:26751443

Design and Development of Layered Security: Future Enhancements and Directions in Transmission

Directory of Open Access Journals (Sweden)

Aamir Shahzad

2016-01-01

Full Text Available Today, security is a prominent issue when any type of communication is being undertaken. Like traditional networks, supervisory control and data acquisition (SCADA systems suffer from a number of vulnerabilities. Numerous end-to-end security mechanisms have been proposed for the resolution of SCADA-system security issues, but due to insecure real-time protocol use and the reliance upon open protocols during Internet-based communication, these SCADA systems can still be compromised by security challenges. This study reviews the security challenges and issues that are commonly raised during SCADA/protocol transmissions and proposes a secure distributed-network protocol version 3 (DNP3 design, and the implementation of the security solution using a cryptography mechanism. Due to the insecurities found within SCADA protocols, the new development consists of a DNP3 protocol that has been designed as a part of the SCADA system, and the cryptographically derived security is deployed within the application layer as a part of the DNP3 stack.

Implementation of Olfactory Bulb Glomerular Layer Computations in a Digital Neurosynaptic Core

Directory of Open Access Journals (Sweden)

Nabil eImam

2012-06-01

Full Text Available We present a biomimetic system that captures essential functional properties of the glomerular layer of the mammalian olfactory bulb, specifically including its capacity to decorrelate similar odor representations without foreknowledge of the statistical distributions of analyte features. Our system is based on a digital neuromorphic chip consisting of 256 leaky-integrate-and-fire neurons, 1024x256 crossbar synapses, and AER communication circuits. The neural circuits configured in the chip reflect established connections among mitral cells, periglomerular cells, external tufted cells and superficial short axon cells within the olfactory bulb, and accept input from convergent sets of sensors configured as olfactory sensory neurons. This configuration generates functional transformations comparable to those observed in the glomerular layer of the mammalian olfactory bulb. Our circuits, consuming only 45 pJ of active power per spike with a power supply voltage of 0.85V, can be used as the first stage of processing in low-power artificial chemical sensing devices inspired by natural olfactory systems.

Diffraction of Elastic Waves in Fluid-Layered Solid Interfaces by an Integral Formulation

Directory of Open Access Journals (Sweden)

J. E. Basaldúa-Sánchez

2013-01-01

Full Text Available In the present communication, scattering of elastic waves in fluid-layered solid interfaces is studied. The indirect boundary element method is used to deal with this wave propagation phenomenon in 2D fluid-layered solid models. The source is represented by Hankel’s function of second kind and this is always applied in the fluid. Our method is an approximate boundary integral technique which is based upon an integral representation for scattered elastic waves using single-layer boundary sources. This approach is typically called indirect because the sources’ strengths are calculated as an intermediate step. In addition, this formulation is regarded as a realization of Huygens’ principle. The results are presented in frequency and time domains. Various aspects related to the different wave types that emerge from this kind of problems are emphasized. A near interface pulse generates changes in the pressure field and can be registered by receivers located in the fluid. In order to show the accuracy of our method, we validated the results with those obtained by the discrete wave number applied to a fluid-solid interface joining two half-spaces, one fluid and the other an elastic solid.

The Communication System using One Communication Line during a Physical Contact

OpenAIRE

平田, 隆幸; 大場, 公隆

2009-01-01

The communication system during a physical contact for swarm robots was modified. An algorithm for the contact communication system using one communication line was proposed. Although we don't aim to make the perfect communication system free from a miss in data transmission, the success rate of communication is an important factor for the design of communication system. We tested the performance of of our modified communication system. The success rate of communication was considerably impro...

Visible Light Communications towards 5G

Directory of Open Access Journals (Sweden)

S. Zvanovec

2015-04-01

Full Text Available 5G networks have to offer extremely high capacity for novel streaming applications. One of the most promising approaches is to embed large numbers of co-operating small cells into the macro-cell coverage area. Alternatively, optical wireless based technologies can be adopted as an alternative physical layer offering higher data rates. Visible light communications (VLC is an emerging technology for future high capacity communication links (it has been accepted to 5GPP in the visible range of the electromagnetic spectrum (~370–780 nm utilizing light-emitting diodes (LEDs simultaneously provide data transmission and room illumination. A major challenge in VLC is the LED modulation bandwidths, which are limited to a few MHz. However, myriad gigabit speed transmission links have already been demonstrated. Non line-of-sight (NLOS optical wireless is resistant to blocking by people and obstacles and is capable of adapting its’ throughput according to the current channel state information. Concurrently, organic polymer LEDs (PLEDs have become the focus of enormous attention for solid-state lighting applications due to their advantages over conventional white LEDs such as ultra-low costs, low heating temperature, mechanical flexibility and large photoactive areas when produced with wet processing methods. This paper discusses development of such VLC links with a view to implementing ubiquitous broadcasting networks featuring advanced modulation formats such as orthogonal frequency division multiplexing (OFDM or carrier-less amplitude and phase modulation (CAP in conjunction with equalization techniques. Finally, this paper will also summarize the results of the European project ICT COST IC1101 OPTICWISE (Optical Wireless Communications - An Emerging Technology dealing VLC and OLEDs towards 5G networks.

Multi-layers castings

Directory of Open Access Journals (Sweden)

J. Szajnar

2010-01-01

Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

DC microgrid power flow optimization by multi-layer supervision control. Design and experimental validation

International Nuclear Information System (INIS)

Sechilariu, Manuela; Wang, Bao Chao; Locment, Fabrice; Jouglet, Antoine

2014-01-01

Highlights: • DC microgrid (PV array, storage, power grid connection, DC load) with multi-layer supervision control. • Power balancing following power flow optimization while providing interface for smart grid communication. • Optimization under constraints: storage capability, grid power limitations, grid time-of-use pricing. • Experimental validation of DC microgrid power flow optimization by multi-layer supervision control. • DC microgrid able to perform peak shaving, to avoid undesired injection, and to make full use of locally energy. - Abstract: Urban areas have great potential for photovoltaic (PV) generation, however, direct PV power injection has limitations for high level PV penetration. It induces additional regulations in grid power balancing because of lacking abilities of responding to grid issues such as reducing grid peak consumption or avoiding undesired injections. The smart grid implementation, which is designed to meet these requirements, is facilitated by microgrids development. This paper presents a DC microgrid (PV array, storage, power grid connection, DC load) with multi-layer supervision control which handles instantaneous power balancing following the power flow optimization while providing interface for smart grid communication. The optimization takes into account forecast of PV power production and load power demand, while satisfying constraints such as storage capability, grid power limitations, grid time-of-use pricing and grid peak hour. Optimization, whose efficiency is related to the prediction accuracy, is carried out by mixed integer linear programming. Experimental results show that the proposed microgrid structure is able to control the power flow at near optimum cost and ensures self-correcting capability. It can respond to issues of performing peak shaving, avoiding undesired injection, and making full use of locally produced energy with respect to rigid element constraints

An improved broadband E patch microstrip antenna for wireless communications

Science.gov (United States)

Bzeih, Amer; Chahine, Soubhi Abou; Kabalan, Karim Y.; El-Hajj, Ali; Chehab, Ali

2007-12-01

A broadband probe-fed microstrip antenna with E-shaped patch on a single-layer air substrate is investigated. Bandwidth enhancement of the antenna is achieved by inserting two parallel slots into its radiating patch. The effects of the antenna parameters are analyzed, and their optimal values for broadband operation are obtained. The design parameters are formulated as a function of the center frequency, and the empirical equations are validated by simulation. A 51.5% enhanced E patch antenna for modern wireless communications (Personal Communications Service, Digital Cellular System, Universal Mobile Telecommunications System, Wireless Local Area Network 802.11 b/g, and Bluetooth) is designed, simulated, fabricated, and measured. A comparison between simulated and measured results is presented, and it showed satisfactory agreement. Moreover, the effect of incorporating more parallel slots into the radiating patch is investigated. The antenna is designed and simulated for different scenarios (four slots, six slots, and eight slots), where a bandwidth of 57% is achieved in the eight-slot design.

Automatic settlement analysis of single-layer armour layers

NARCIS (Netherlands)

Hofland, B.; van gent, Marcel

2016-01-01

A method to quantify, analyse, and present the settlement of single-layer concrete armour layers of coastal structures is presented. The use of the image processing technique for settlement analysis is discussed based on various modelling
studies performed over the years. The accuracy of the

Modeling and characterization of different channels based on human body communication.

Science.gov (United States)

Jingzhen Li; Zedong Nie; Yuhang Liu; Lei Wang

2017-07-01

Human body communication (HBC), which uses the human body as a transmission medium for electrical signals, provides a prospective communication solution for body sensor networks (BSNs). In this paper, an inhomogeneous model which includes the tissue layers of skin, fat, and muscle is proposed to study the propagation characteristics of different HBC channels. Specifically, the HBC channels, namely, the on-body to on-body (OB-OB)channel, on-body to in-body (OB-IB) channel, in-body to on-body (IB-OB) channel, and in-body to in-body (IB-IB)channel, are studied over different frequencies (from 1MHz to 100MHz) through numerical simulations with finite-difference time-domain (FDTD) method. The results show that the gain of OB-IB channel and IB-OB channel is almost the same. The gain of IB-IB channel is greater than other channels in the frequency range 1MHz to 70MHz. In addition, the gain of all channels is associated with the channel length and communication frequency. The simulations are verified by experimental measurements in a porcine tissue sample. The results show that the simulations are in agreement with the measurements.

Capacity of Wireless Ad Hoc Networks with Opportunistic Collaborative Communications

Directory of Open Access Journals (Sweden)

Simeone O

2007-01-01

Full Text Available Optimal multihop routing in ad hoc networks requires the exchange of control messages at the MAC and network layer in order to set up the (centralized optimization problem. Distributed opportunistic space-time collaboration (OST is a valid alternative that avoids this drawback by enabling opportunistic cooperation with the source at the physical layer. In this paper, the performance of OST is investigated. It is shown analytically that opportunistic collaboration outperforms (centralized optimal multihop in case spatial reuse (i.e., the simultaneous transmission of more than one data stream is not allowed by the transmission protocol. Conversely, in case spatial reuse is possible, the relative performance between the two protocols has to be studied case by case in terms of the corresponding capacity regions, given the topology and the physical parameters of network at hand. Simulation results confirm that opportunistic collaborative communication is a promising paradigm for wireless ad hoc networks that deserves further investigation.

Capacity of Wireless Ad Hoc Networks with Opportunistic Collaborative Communications

Directory of Open Access Journals (Sweden)

O. Simeone

2007-03-01

Full Text Available Optimal multihop routing in ad hoc networks requires the exchange of control messages at the MAC and network layer in order to set up the (centralized optimization problem. Distributed opportunistic space-time collaboration (OST is a valid alternative that avoids this drawback by enabling opportunistic cooperation with the source at the physical layer. In this paper, the performance of OST is investigated. It is shown analytically that opportunistic collaboration outperforms (centralized optimal multihop in case spatial reuse (i.e., the simultaneous transmission of more than one data stream is not allowed by the transmission protocol. Conversely, in case spatial reuse is possible, the relative performance between the two protocols has to be studied case by case in terms of the corresponding capacity regions, given the topology and the physical parameters of network at hand. Simulation results confirm that opportunistic collaborative communication is a promising paradigm for wireless ad hoc networks that deserves further investigation.

COMMUNICATIVE CULTURE AND THE ROLE OF PHATIC FUNCTION IN INTERPERSONAL COMMUNICATION

OpenAIRE

Kosova Kristina Igorevna

2015-01-01

The article analyses a language function which helps to personalize and control communication arranging it in accordance with communicative norms and rituals. The choice of forms of interpersonal communication is regulated by norms and motivated by conditions of communicative behavior. Interpersonal communication peculiarities are connected in particular with the forms of indirect communication implementing the phatic language function. Phatic communication is viewed as a special form of inte...

Communication and cooperation in underwater acoustic networks

Science.gov (United States)

Yerramalli, Srinivas

In this thesis, we present a study of several problems related to underwater point to point communications and network formation. We explore techniques to improve the achievable data rate on a point to point link using better physical layer techniques and then study sensor cooperation which improves the throughput and reliability in an underwater network. Robust point-to-point communications in underwater networks has become increasingly critical in several military and civilian applications related to underwater communications. We present several physical layer signaling and detection techniques tailored to the underwater channel model to improve the reliability of data detection. First, a simplified underwater channel model in which the time scale distortion on each path is assumed to be the same (single scale channel model in contrast to a more general multi scale model). A novel technique, which exploits the nature of OFDM signaling and the time scale distortion, called Partial FFT Demodulation is derived. It is observed that this new technique has some unique interference suppression properties and performs better than traditional equalizers in several scenarios of interest. Next, we consider the multi scale model for the underwater channel and assume that single scale processing is performed at the receiver. We then derive optimized front end pre-processing techniques to reduce the interference caused during single scale processing of signals transmitted on a multi-scale channel. We then propose an improvised channel estimation technique using dictionary optimization methods for compressive sensing and show that significant performance gains can be obtained using this technique. In the next part of this thesis, we consider the problem of sensor node cooperation among rational nodes whose objective is to improve their individual data rates. We first consider the problem of transmitter cooperation in a multiple access channel and investigate the stability of

Cross-Cultural Communication Patterns in Computer Mediated Communication

Science.gov (United States)

Panina, Daria; Kroumova, Maya

2015-01-01

There are important cultural differences in attitudes towards and use of electronic text communication. Consistent with Hall's high-context/low-context conceptualization of culture, electronic inter-cultural communication, just as verbal inter-cultural communication, is affected by the culturally-specific assumptions and preferences of message…

Novel Electrospun Dual-Layered Composite Nanofibrous Membrane Endowed with Electricity-Magnetism Bifunctionality at One Layer and Photoluminescence at the Other Layer.

Science.gov (United States)

Wang, Zijiao; Ma, Qianli; Dong, Xiangting; Li, Dan; Xi, Xue; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

2016-10-05

Dual-layered composite nanofibrous membrane equipped with electrical conduction, magnetism and photoluminescence trifunctionality is constructed via electrospinning. The composite membrane consists of a polyaniline (PANI)/Fe 3 O 4 nanoparticles (NPs)/polyacrylonitrile (PAN) tuned electrical-magnetic bifunctional nanofibrous layer at one side and a Eu(TTA) 3 (TPPO) 2 /polyvinylpyrrolidone (PVP) photoluminescent nanofibrous layer at the other side, and the two layers are tightly combined face-to-face together into the novel dual-layered composite membrane with trifunctionality. The electric conductivity and magnetism of electrical-magnetic bifunctionality can be respectively tunable via modulating the respective PANI and Fe 3 O 4 NPs contents, and the highest electric conductivity approaches the order of 1 × 10 -2 S cm -1 . Predominant red emission at 615 nm can be obviously observed in the photoluminescent layer under 366 nm excitation. Moreover, the luminescent intensity of photoluminescent layer is almost unaffected by the electrical-magnetic bifunctional layer because of the fact that the photoluminescent materials have been successfully isolated from dark-colored PANI and Fe 3 O 4 NPs. The novel dual-layered composite nanofibrous membrane with trifunctionality has potentials in many fields. Furthermore, the design philosophy and fabrication method for the dual-layered multifunctional membrane provide a new and facile strategy toward other membranes with multifunctionality.

Layer-by-Layer-Assembled High-Performance Broadband Antireflection Coatings

KAUST Repository

Shimomura, Hiroomi; Gemici, Zekeriyya; Cohen, Robert E.; Rubner, Michael F.

2010-01-01

uniformity, thickness control, roughness control, mechanical durability, and incorporation of a diverse set of functional organic molecules into nanoparticle thin films are major challenges. We have used the electrostatic layer-by-layer assembly technique

Characteristics of the magnetospheric boundary layer and magnetopause layer as observed by Imp 6

International Nuclear Information System (INIS)

Eastman, T.E.; Hones, E.W. Jr.

1979-01-01

Imp 6 observations of the low-latitude magnetospheric boundary layer indicate that the plasma within it is supplied primarily by direct entry of magnetosheath plasma across the magnetopause layer. We define the magnetopause layer as the current layer (separating the magnetosheath from the boundary layer) through which the magnetic field shifts in direction. High temporal resolution (3-s average) data reveal that in a majority of Imp 6 magnetopause crossing, no distinct changes in electron density or energry spectra are observed at the magne opause layer. In all Imp 6 crossings, some magnetosheathlike plasma is observed earthward of the magnetopause layer, implying the existence of a boundary layer. Boundary layer electron energy spectra are often virtually indistinguishable from the adjacent magnetosheath spectra. Low-latitude boundary layer bulk plasma flow as observed by Imp 6 almost always has an antisunward component and often has a significant cross-field component. The boundary layer thickness is highly variable and is generally much larger than the magnetopause layer thickness. Energetic electron pitch angle distributions indicate that the low-latitude boundary layers is normally on closed field lines. We conclude that diffusive as well as nondiffusive processes probably contribute to the entry of magnetosheath plasma into the boundary layer

Single Layered Versus Double Layered Intestinal Anastomosis: A Randomized Controlled Trial

Science.gov (United States)

Mohapatra, Vandana; Singh, Surendra; Rath, Pratap Kumar; Behera, Tapas Ranjan

2017-01-01

Introduction Gastrointestinal anastomosis is one of the most common procedures being performed in oesophagogastric, hepatobiliary, bariatric, small bowel and colorectal surgery; however, the safety and efficacy of single layer or double layer anastomotic technique is still unclear. Aim To assess and compare the efficacy, safety and cost effectiveness of single layered versus double layered intestinal anastomosis. Materials and Methods This prospective, double-blind, randomized controlled comparative study comprised of patients who underwent intestinal resection and anastomosis. They were randomly assigned to undergo either single layered extra-mucosal anastomosis (Group-A) or double layered intestinal anastomosis (Group-B). Primary outcome measures included average time taken for anastomosis, postoperative complications, mean duration of hospital stay and cost of suture material used; secondary outcome measures assessed the postoperative return of bowel function. Statistical analysis was done by Chi-square test and student t-test. Results A total of 97 participants were randomized. Fifty patients were allocated to single layered extramucosal continuous anastomosis (Group-A) and 47 patients to double layered anastomosis (Group-B). The patients in each group were well matched for age, sex and diagnosis. The mean time taken for anastomosis (15.12±2.27 minutes in Group-A versus 24.38±2.26 minutes in Group-B) and the length of hospital stay (5.90±1.43 days in Group-A versus 7.29±1.89 days in Group-B) was significantly shorter in Group-A {p-value anastomosis. However, there was no significant difference in the complication rates between the two groups. Conclusion It can be concluded that single layered extramucosal continuous intestinal anastomosis is equally safe and perhaps more cost effective than the conventional double layered method and may represent the optimal choice for routine surgical practice. PMID:28764239

Link adaptation performance evaluation for a MIMO-OFDM physical layer in a realistic outdoor environment

OpenAIRE

Han, C; Armour, SMD; Doufexi, A; Ng, KH; McGeehan, JP

2006-01-01

This paper presents a downlink performance analysis of a link adaptation (LA) algorithm applied to a MIMO-OFDM Physical Layer (PHY) which is a popular candidate for future generation cellular communication systems. The new LA algorithm attempts to maximize throughput and adaptation between various modulation and coding schemes in combination with both space-time block codes (STBC) and spatial multiplexing (SM) is based on knowledge of SNR and H matrix determinant; the parameters which are fou...

Advanced Software Ground Station and UAV Development for NLoS Control Using Mobile Communications

Directory of Open Access Journals (Sweden)

Amr AbdElHamid

2015-01-01

Full Text Available Over the last decades, Unmanned Aerial Systems (UASs have gained much attention due to their various applications in different sections. However, their communication range is limited to utilized communication equipment. Therefore, utilization of GSM channels opens a new prospect towards long distance UAV missions and mobile command and control centers. This paper demonstrates new design and development of a small-scale UAV and a Ground Control Station (GCS using GSM bidirectional communications for Non-Line of Sight (NLoS long range control. GCSs are considered the front end node in UAV guidance process. Therefore, the proposed GCS employs a two-layer framework to consider all ground pilot requirements. Moreover, a new exploitation of global weather forecast data is added to the GCS. On the other hand, the proposed airborne system utilizes a new integration of different Commercial off-the-Shelf (COTS components and excludes short range receivers. The ground and flight tests show that stable bidirectional GSM communication is established, reliable hardware integration is accomplished, real time performance is achieved, GCS functional fidelity is obtained, and low cost is maintained. Finally, some qualitative aspects of the proposed platform are presented to address the detailed features.

Three-dimensional image capturing and representation for multimedia ambiance communication

Science.gov (United States)

Ichikawa, Tadashi; Iwasawa, Shoichiro; Yamada, Kunio; Kanamaru, Toshifumi; Naemura, Takeshi; Aizawa, Kiyoharu; Morishima, Shigeo; Saito, Takahiro

2001-02-01

Multimedia Ambiance Communication is as a means of achieving shared-space communication in an immersive environment consisting of an arch-type stereoscopic projection display. Our goal is to enable shared-space communication by creating a photo-realistic three-dimensional (3D) image space that users can feel a part of. The concept of a layered structure defined for painting, such as long-range, mid-range, and short-range views, can be applied to a 3D image space. New techniques, such as two-plane expression, high quality panorama image generation and setting representation for image processing, 3D image representation and generation for photo- realistic 3D image space have been developed. Also, we propose a life-like avatar within the 3D image space. To obtain the characteristics of user's body, a human subject is scanned using a CyberwareTM whole body scanner. The output from the scanner, a range image, is a good start for modeling the avatar's geometric shape. A generic human surface model is fitted to the range image. The obtained model is topologically equivalent even if our method is applied to another subject. If a generic model with motion definitions is employed, and common motion rules can be applied to all models made from the generic model.

Semiconductor Three-Dimensional Photonic Crystals with Novel Layer-by-Layer Structures

Directory of Open Access Journals (Sweden)

Satoshi Iwamoto

2016-05-01

Full Text Available Three-dimensional photonic crystals (3D PhCs are a fascinating platform for manipulating photons and controlling their interactions with matter. One widely investigated structure is the layer-by-layer woodpile structure, which possesses a complete photonic bandgap. On the other hand, other types of 3D PhC structures also offer various possibilities for controlling light by utilizing the three dimensional nature of structures. In this article, we discuss our recent research into novel types of layer-by-layer structures, including the experimental demonstration of a 3D PhC nanocavity formed in a <110>-layered diamond structure and the realization of artificial optical activity in rotationally stacked woodpile structures.

Optical properties of single-layer, double-layer, and bulk MoS2

Energy Technology Data Exchange (ETDEWEB)

Molina-Sanchez, Alejandro; Wirtz, Ludger [University of Luxembourg (Luxembourg); Hummer, Kerstin [University of Vienna, Vienna (Austria)

2013-07-01

The rise of graphene has brought attention also to other layered materials that can complement graphene or that can be an alternative in applications as transistors. Single-layer MoS{sub 2} has shown interesting electronic and optical properties such as as high electron mobility at room temperature and an optical bandgap of 1.8 eV. This makes the material suitable for transistors or optoelectronic devices. We present a theoretical study of the optical absorption and photoluminescence spectra of single-layer, double-layer and bulk MoS{sub 2}. The excitonic states have been calculated in the framework of the Bethe-Salpeter equation, taking into account the electron-hole interaction via the screened Coulomb potential. In addition to the step-function like behaviour that is typical for the joint-density of states of 2D materials with parabolic band dispersion, we find a bound excitonic peak that is dominating the luminescence spectra. The peak is split due to spin-orbit coupling for the single-layer and split due to layer-layer interaction for few-layer and bulk MoS{sub 2}. We discuss the changes of the optical bandgap and of the exciton binding energy with the number of layers, comparing our results with the reported experimental data.

I-centric Communications

CERN Document Server

Arbanowski, S; Steglich, S; Popescu-Zeletin, R

2001-01-01

During the last years, a variety of concepts for service integration and corresponding systems have gained momentum. On the one hand, they aim for the interworking and integration of classical telecommunications and data communications services. On the other hand, they are focusing on universal service access from a variety of end user systems. Looking at humans' communication behavior and communication space, it is obvious that human beings interact frequently in a set of contexts in their environment (communication space). Following this view, we want to build communication systems on the analysis of the individual communication spaces. The results are communication systems adapted to the specific demands of each individual. The authors introduce I-centric Communication Systems, an approach to design communication systems which adapt to the individual communication space and individual environment and situation. In this context "I" means I, or individual, "Centric" means adaptable to I requirements and a ce...

Mayday system infiniti communicator; Kinkyu tsuho system Infiniti Communicator

Energy Technology Data Exchange (ETDEWEB)

Iijima, Y.; Ito, T.; Isono, Y.; Sekiya, M.; Koizumi, H.; Miyazaki, S.; Kishore, A.; Lawor, D. [Nissan Motor Co. Ltd., Tokyo (Japan)

1999-02-01

To respond to emergency situations associated with vehicle accidents and mechanical problems on the road, a novel emergency communication system, which combines vehicle electronics, GPS and communication systems, has been developed and is contributing to safety in the U.S. In addition to emergency communication, other features including theft protection, security, convenience features, etc. are to be added to this system in the future. An emergency communication system, `The Infiniti Communicator`, which began its service in March 1998 under such a market trend, is explained in this report. (author)

Energy management and multi-layer control of networked microgrids

Science.gov (United States)

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.

Design of the HELICS High-Performance Transmission-Distribution-Communication-Market Co-Simulation Framework: Preprint

Energy Technology Data Exchange (ETDEWEB)

Palmintier, Bryan S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Krishnamurthy, Dheepak [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Top, Philip [Lawrence Livermore National Laboratories; Smith, Steve [Lawrence Livermore National Laboratories; Daily, Jeff [Pacific Northwest National Laboratory; Fuller, Jason [Pacific Northwest National Laboratory

2017-09-12

This paper describes the design rationale for a new cyber-physical-energy co-simulation framework for electric power systems. This new framework will support very large-scale (100,000+ federates) co-simulations with off-the-shelf power-systems, communication, and end-use models. Other key features include cross-platform operating system support, integration of both event-driven (e.g. packetized communication) and time-series (e.g. power flow) simulation, and the ability to co-iterate among federates to ensure model convergence at each time step. After describing requirements, we begin by evaluating existing co-simulation frameworks, including HLA and FMI, and conclude that none provide the required features. Then we describe the design for the new layered co-simulation architecture.

Communication Acoustics

DEFF Research Database (Denmark)

Blauert, Jens

Communication Acoustics deals with the fundamentals of those areas of acoustics which are related to modern communication technologies. Due to the advent of digital signal processing and recording in acoustics, these areas have enjoyed an enormous upswing during the last 4 decades. The book...... the book a source of valuable information for those who want to improve or refresh their knowledge in the field of communication acoustics - and to work their way deeper into it. Due to its interdisciplinary character Communication Acoustics is bound to attract readers from many different areas, such as......: acoustics, cognitive science, speech science, and communication technology....

Formation of double layers

International Nuclear Information System (INIS)

Leung, P.; Wong, A.Y.; Quon, B.H.

1981-01-01

Experiments on both stationary and propagating double layers and a related analytical model are described. Stationary double layers were produced in a multiple plasma device, in which an electron drift current was present. An investigation of the plasma parameters for the stable double layer condition is described. The particle distribution in the stable double layer establishes a potential profile, which creates electron and ion beams that excite plasma instabilities. The measured characteristics of the instabilities are consistent with the existence of the double layer. Propagating double layers are formed when the initial electron drift current is large. Ths slopes of the transition region increase as they propagate. A physical model for the formation of a double layer in the experimental device is described. This model explains the formation of the low potential region on the basis of the space charge. This space charge is created by the electron drift current. The model also accounts for the role of ions in double layer formation and explains the formation of moving double layers. (Auth.)

Effect of layer-by-layer polyelectrolyte method on encapsulation of vanillin.

Science.gov (United States)

Noshad, Mohammad; Mohebbi, Mohebbat; Shahidi, Fakhri; Koocheki, Arash

2015-11-01

The objective of this work was to microencapsulate vanillin by multilayer emulsion followed by spray drying, aiming to protect it and control its release. An electrostatic layer-by-layer deposition method was used to create the multilayered interfacial membranes around microcapsules with different compositions: (i) one-layer (soy protein isolate); (ii) two-layer (soy protein isolate - OSA starch); (iii) three-layer (soy protein isolate - OSA starch - Chitosan). The morphology of the microcapsules was analyzed by scanning electronic microscopy. The hygroscopicity, solubility, particle size, encapsulation efficiency, Fourier transform infrared spectroscopy and release into water (37°C and 80°C) were also examined. FTIR confirmed the interaction between the wall materials. All microcapsules were not very water-soluble or hygroscopic while three-layer microcapsules compared to one and two layer microcapsules have lower moisture content and predominantly shriveled surfaces. The results indicated it was possible to encapsulate vanillin with the techniques employed and that these protected the vanillin even at 80°C. The reduced solubility and low release rates indicated the enormous potential of the vehicle developed in controlling the release of the vanillin into the food and pharmaceuticals. Copyright © 2015 Elsevier B.V. All rights reserved.

Spontaneous layering of porous silicon layers formed at high current densities

Energy Technology Data Exchange (ETDEWEB)

Parkhutik, Vitali; Curiel-Esparza, Jorge; Millan, Mari-Carmen [R and D Center MTM, Technical University of Valencia, Valencia (Spain); Albella, Jose [Institute of Materials Science (ICMM CSIC) Madrid (Spain)

2005-06-01

We report here a curious effect of spontaneous fracturing of the silicon layers formed in galvanostatic conditions at medium and high current densities. Instead of formation of homogeneous p-Si layer as at low currents, a stack of thin layers is formed. Each layer is nearly separated from others and possesses rather flat interfaces. The effects is observed using p{sup +}-Si wafers for the p-Si formation and starts being noticeable at above 100 mA/cm{sup 2}. We interpret these results in terms of the porous silicon growth model where generation of dynamic mechanical stress during the p-Si growth causes sharp changes in Si dissolution mechanism from anisotropic etching of individual needle-like pores in silicon to their branching and isotropic etching. At this moment p-Si layer loses its adhesion to the surface of Si wafer and another p-Si layer starts growing. One of the mechanisms triggering on the separation of p-Si layers from one another is a fluctuation of local anodic current in the pore bottoms associated with gas bubble evolution during the p-Si formation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Turbulent current layer equilibrium and current layer of the Earth magnetotail

International Nuclear Information System (INIS)

Antonova, E.E.; Ovchinnikov, I.L.

1996-01-01

Analysis of distribution of plasma and magnetic field concentration in the unidimensional current layer under the condition of equality of the current inflowing into the layer and the counter diffusion current by various dependences of the regular velocity and the turbulent diffusion coefficient on the magnetic field. Corresponding two-dimensional solutions are obtained in the tail approximation. Comparison of the model turbulent current layer with characteristics of the plasma layer of the Earth magnetosphere tail is carried out. 16 refs., 3 figs

Developing Intercultural Communicative Competence in ELF Communication

Directory of Open Access Journals (Sweden)

Lili Cavalheiro

2015-06-01

Full Text Available The traditional notion of English as a foreign language solely for communicating with native speakers can no longer be applied in a world that is constantly changing, hence paving the way for an alternative use of the language known as English as a lingua franca. As a result, instead of focusing only on grammatical correctness, research into language pedagogy has also come to recognize the importance of exploring bottom-up learning processes, and developing intercultural communicative competence (ICC and more communicative-based methods. Nowadays, it is essential to acquire the knowledge, skills, attitudes and critical cultural awareness necessary to communicate successfully. To show the importance of integrating ICC in language pedagogy, a recording from the Vienna-Oxford International Corpus of English is analysed here to demonstrate the significance of developing critical awareness as well as several communicative strategies, so that language learners can afterwards have the necessary ICC to interact in today’s multi-lingual/cultural society.

Communication devices for network-hopping communications and methods of network-hopping communications

Science.gov (United States)

Buttles, John W

2013-04-23

Wireless communication devices include a software-defined radio coupled to processing circuitry. The system controller is configured to execute computer programming code. Storage media is coupled to the system controller and includes computer programming code configured to cause the system controller to configure and reconfigure the software-defined radio to operate on each of a plurality of communication networks according to a selected sequence. Methods for communicating with a wireless device and methods of wireless network-hopping are also disclosed.

Generic communications index. Listings of communications 1971-1989

Energy Technology Data Exchange (ETDEWEB)

Hagemeyer, D; Towle, H

1991-05-01

As part of its program to feed back information on operating experience to industry, the U.S. Nuclear Regulatory Commission (NRC) issues generic communications called bulletins (about 5/yr), circulars (now discontinued), generic letters (about 20/yr), and information notices (about 100/yr). The report presents an updated Generic Communications Index (GCI; previously published in NUREG/CR-4690, Vol. 1, December 1987) of all such communications from 1971, when such documentation started, to 1989. The GCI consists of records, one for each communication, containing fields for identification number, title, NRC technical contact, general system or topic, specific component or topic, cause or defect, potential effect, remarks, and vendors involved. To facilitate information retrieval, the report also contains topical listings of generic communications numbers. (author)

Communications article

KAUST Repository

Fariborzi, Hossein

2017-01-01

Seamless, covert communications using a communications system integrated or incorporated within an article of clothing is described. In one embodiment, the communications system is integrated or incorporated into a shoe insole and includes a haptic

An Optimal Estimation Method to Obtain Surface Layer Turbulent Fluxes from Profile Measurements

Science.gov (United States)

Kang, D.

2015-12-01

In the absence of direct turbulence measurements, the turbulence characteristics of the atmospheric surface layer are often derived from measurements of the surface layer mean properties based on Monin-Obukhov Similarity Theory (MOST). This approach requires two levels of the ensemble mean wind, temperature, and water vapor, from which the fluxes of momentum, sensible heat, and water vapor can be obtained. When only one measurement level is available, the roughness heights and the assumed properties of the corresponding variables at the respective roughness heights are used. In practice, the temporal mean with large number of samples are used in place of the ensemble mean. However, in many situations the samples of data are taken from multiple levels. It is thus desirable to derive the boundary layer flux properties using all measurements. In this study, we used an optimal estimation approach to derive surface layer properties based on all available measurements. This approach assumes that the samples are taken from a population whose ensemble mean profile follows the MOST. An optimized estimate is obtained when the results yield a minimum cost function defined as a weighted summation of all error variance at each sample altitude. The weights are based one sample data variance and the altitude of the measurements. This method was applied to measurements in the marine atmospheric surface layer from a small boat using radiosonde on a tethered balloon where temperature and relative humidity profiles in the lowest 50 m were made repeatedly in about 30 minutes. We will present the resultant fluxes and the derived MOST mean profiles using different sets of measurements. The advantage of this method over the 'traditional' methods will be illustrated. Some limitations of this optimization method will also be discussed. Its application to quantify the effects of marine surface layer environment on radar and communication signal propagation will be shown as well.

Energy efficient three-layer panels and elastic compliance of their middle layer

Directory of Open Access Journals (Sweden)

Petrov Stanislav

2017-01-01

Full Text Available Three-layer panels are referred to light weight energy efficient building envelopes. According to current trends, mineral wool from basalt fiber is preferable to be used as panels middle layer. All three-layers of the construction together account for mechanical properties, though these layers taken separately have very different mechanical properties. The work of such a composite design has a number of features that require careful consideration when calculating the panels for strength. Thus, it has not yet been described how squeeze reduction of a relatively soft middle layer affects the load bearing capacity of a panel. When panels are exposed to external loads, their middle layer is squeezed thus changing the characteristics of the panel. This effect is particularly evident in supporting structures. Besides, squeeze reduction of the middle layer changes its elastic-plastic propeties. The purpose of this work is to study the effect of the middle layer of an energy efficient panel squeeze reduction on its load bearing capacity. When solving this task, the authors worked out a methodology which takes into account squeeze reduction of a middle layer and its effect on load bearing capacity of the panel. The researches introduced an algorithm for solving this task and created a tool that allows to easily receive the exact solution. The paper presents this methodology and describes a computer program for calculating three-layer panels with account of changing elastic compliance of a middle layer. The main result of the work is an extended methodology of calculation of the panels and an obtained engineering tool that allows to quickly obtain an extended solution.

Electronic energy loss spectra from mono-layer to few layers of phosphorene

International Nuclear Information System (INIS)

Mohan, Brij; Thakur, Rajesh; Ahluwalia, P. K.

2016-01-01

Using first principles calculations, electronic and optical properties of few-layers phosphorene has been investigated. Electronic band structure show a moderate band gap of 0.9 eV in monolayer phosphorene which decreases with increasing number of layers. Optical properties of few-layers of phosphorene in infrared and visible region shows tunability with number of layers. Electron energy loss function has been plotted and huge red shift in plasmonic behaviours is found. These tunable electronic and optical properties of few-layers of phosphorene can be useful for the applications of optoelectronic devices.

Electronic energy loss spectra from mono-layer to few layers of phosphorene

Energy Technology Data Exchange (ETDEWEB)

Mohan, Brij, E-mail: brijmohanhpu@yahoo.com; Thakur, Rajesh; Ahluwalia, P. K. [Department of Physics, Himachal Pradesh University, Shimla (HP) India 171005 (India)

2016-05-23

Using first principles calculations, electronic and optical properties of few-layers phosphorene has been investigated. Electronic band structure show a moderate band gap of 0.9 eV in monolayer phosphorene which decreases with increasing number of layers. Optical properties of few-layers of phosphorene in infrared and visible region shows tunability with number of layers. Electron energy loss function has been plotted and huge red shift in plasmonic behaviours is found. These tunable electronic and optical properties of few-layers of phosphorene can be useful for the applications of optoelectronic devices.

INTERCULTURAL COMMUNICATION PATTERNS AND LANGUAGE USE IN COMPUTER MEDIATED-COMMUNICATION

OpenAIRE

Adriana Teodorescu

2012-01-01

This paper aims at analyzing the degree to which intercultural communication patterns are embedded in computer-mediated communication. Drawing on Hall's and Hofstede's intercultural communication dimensions, this study evaluates empirically high-versus-low context cultural orientations as reflected in the electronic medium, namely the blog, in three different cultures. Cultural variation is also analyzed in linguistic features and communication style in a synchronous mode of communication, by...

Participatory Communication

DEFF Research Database (Denmark)

Tufte, Thomas

This user guide on participatory communication aims to answer the following questions: What do we mean when we say participatory communication? What are the practical implications of working with participatory communication strategies in development and social change processes? What practical exp......, tools, and experiences on how to implement participatory communications strategies. It is targeted toward government officials, World Bank staff, develompent workers in the field, and civil society....

Business Communication Students' Appraisal of Selected Communication Competencies

Science.gov (United States)

English, Donald E.; Manton, Edgar J.; Walker, Janet I.

2008-01-01

The purpose of this study was to determine business communication students' perception of selected business communication competencies. Students enrolled in business communication classes at Texas A&M University-Commerce from the summer of 2006 until the spring 2007 were survey. Students were asked to evaluate each of the listed 44…

Delivering effective science communication: advice from a professional science communicator.

Science.gov (United States)

Illingworth, Sam

2017-10-01

Science communication is becoming ever more prevalent, with more and more scientists expected to not only communicate their research to a wider public, but to do so in an innovative and engaging manner. Given the other commitments that researchers and academics are required to fulfil as part of their workload models, it is unfair to be expect them to also instantly produce effective science communication events and activities. However, by thinking carefully about what it is that needs to be communicated, and why this is being done, it is possible to develop high-quality activities that are of benefit to both the audience and the communicator(s). In this paper, I present some practical advice for developing, delivering and evaluating effective science communication initiatives, based on over a decade of experience as being a professional science communicator. I provide advice regarding event logistics, suggestions on how to successfully market and advertise your science communication initiatives, and recommendations for establishing effective branding and legacy. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Effects of Communication Expectancies, Actual Communication, and Expectancy Disconfirmation on Evaluations of Communicators and Their Communication Behavior.

Science.gov (United States)

Burgoon, Judee K.; Le Poire, Beth A.

1993-01-01

Investigates the perseverance of preinteraction expectancies in the face of actual communication behavior, the separate effects of personal attribute and communication expectancies, and the role of expectancy confirmation or disconfirmation on postinteraction evaluations. Confirms the validity of expectancy violations theory. (SR)

CHARGE-TRANSFER BETWEEN LAYERS IN MISFIT LAYER COMPOUNDS

NARCIS (Netherlands)

WIEGERS, GA

1995-01-01

Electron donation from MX double layers to TX(2) sandwiches, the interlayer bonding and the localization of conduction electrons in misfit layer compounds (MX)(p)(TX(2))(n) (M=Sn, Pb, Sb, Bi, rare earth metals; T=Ti, V, Cr, Nb, Ta; X=S, Se; 1.08

Correlation analysis between team communication characteristics and frequency of inappropriate communications

International Nuclear Information System (INIS)

Kim, Ar Ryum; Lee, Seung Woo; Park, Jinkyun; Kang, Hyun Gook; Seong, Poong Hyun

2013-01-01

Highlights: • We proposed a method to evaluate team communication characteristics based on social network analysis. • We compare team communication characteristics with the frequency of inappropriate communications. • Frequency of inappropriate communications were decreased when more operators perform the same types of role as others. • Frequency of inappropriate communications were decreased for teams who provide more number of acknowledgment. - Abstract: The characteristics of team communications are important since large process systems such as nuclear power plants, airline, and railways are operated by operating teams. In such situation, inappropriate communications can cause a lack of situational information and lead to serious consequences for the systems. As a result, the communication characteristics of operating teams should be understood in order to extract meaningful insights to address the nature of inappropriate communications. The purpose of this study was to develop a method to evaluate the characteristics of team communications based on social network analysis and compare them with the frequency of inappropriate communications. In order to perform the analysis, verbal protocol data, which were audio-visual recorded under training sessions by operating teams, were used and interfacing system loss of coolant accident scenarios were selected. As a result of the study, it was found that the frequency of inappropriate communications decreased when more operators perform the same types of role as other operators, since they can easily and effectively back up each other. Also, the frequency of inappropriate communication is decreased for teams which provide a relatively large communication content that acknowledge or confirm another communication content

Communicating systems with UML 2 modeling and analysis of network protocols

CERN Document Server

Barrera, David Garduno

2013-01-01

This book gives a practical approach to modeling and analyzing communication protocols using UML 2. Network protocols are always presented with a point of view focusing on partial mechanisms and starting models. This book aims at giving the basis needed for anybody to model and validate their own protocols. It follows a practical approach and gives many examples for the description and analysis of well known basic network mechanisms for protocols.The book firstly shows how to describe and validate the main protocol issues (such as synchronization problems, client-server interactions, layer

SPP: A data base processor data communications protocol

Science.gov (United States)

Fishwick, P. A.

1983-01-01

The design and implementation of a data communications protocol for the Intel Data Base Processor (DBP) is defined. The protocol is termed SPP (Service Port Protocol) since it enables data transfer between the host computer and the DBP service port. The protocol implementation is extensible in that it is explicitly layered and the protocol functionality is hierarchically organized. Extensive trace and performance capabilities have been supplied with the protocol software to permit optional efficient monitoring of the data transfer between the host and the Intel data base processor. Machine independence was considered to be an important attribute during the design and implementation of SPP. The protocol source is fully commented and is included in Appendix A of this report.

Communication theory

DEFF Research Database (Denmark)

Stein, Irene F.; Stelter, Reinhard

2011-01-01

Communication theory covers a wide variety of theories related to the communication process (Littlejohn, 1999). Communication is not simply an exchange of information, in which we have a sender and a receiver. This very technical concept of communication is clearly outdated; a human being...... is not a data processing device. In this chapter, communication is understood as a process of shared meaning-making (Bruner, 1990). Human beings interpret their environment, other people, and themselves on the basis of their dynamic interaction with the surrounding world. Meaning is essential because people...... ascribe specific meanings to their experiences, their actions in life or work, and their interactions. Meaning is reshaped, adapted, and transformed in every communication encounter. Furthermore, meaning is cocreated in dialogues or in communities of practice, such as in teams at a workplace or in school...

SET: Session Layer-Assisted Efficient TCP Management Architecture for 6LoWPAN with Multiple Gateways

Directory of Open Access Journals (Sweden)

Akbar AliHammad

2010-01-01

Full Text Available 6LoWPAN (IPv6 based Low-Power Personal Area Network is a protocol specification that facilitates communication of IPv6 packets on top of IEEE 802.15.4 so that Internet and wireless sensor networks can be inter-connected. This interconnection is especially required in commercial and enterprise applications of sensor networks where reliable and timely data transfers such as multiple code updates are needed from Internet nodes to sensor nodes. For this type of inbound traffic which is mostly bulk, TCP as transport layer protocol is essential, resulting in end-to-end TCP session through a default gateway. In this scenario, a single gateway tends to become the bottleneck because of non-uniform connectivity to all the sensor nodes besides being vulnerable to buffer overflow. We propose SET; a management architecture for multiple split-TCP sessions across a number of serving gateways. SET implements striping and multiple TCP session management through a shim at session layer. Through analytical modeling and ns2 simulations, we show that our proposed architecture optimizes communication for ingress bulk data transfer while providing associated load balancing services. We conclude that multiple split-TCP sessions managed in parallel across a number of gateways result in reduced latency for bulk data transfer and provide robustness against gateway failures.

Oxygen inhibition layer of composite resins: effects of layer thickness and surface layer treatment on the interlayer bond strength.

Science.gov (United States)

Bijelic-Donova, Jasmina; Garoushi, Sufyan; Lassila, Lippo V J; Vallittu, Pekka K

2015-02-01

An oxygen inhibition layer develops on surfaces exposed to air during polymerization of particulate filling composite. This study assessed the thickness of the oxygen inhibition layer of short-fiber-reinforced composite in comparison with conventional particulate filling composites. The effect of an oxygen inhibition layer on the shear bond strength of incrementally placed particulate filling composite layers was also evaluated. Four different restorative composites were selected: everX Posterior (a short-fiber-reinforced composite), Z250, SupremeXT, and Silorane. All composites were evaluated regarding the thickness of the oxygen inhibition layer and for shear bond strength. An equal amount of each composite was polymerized in air between two glass plates and the thickness of the oxygen inhibition layer was measured using a stereomicroscope. Cylindrical-shaped specimens were prepared for measurement of shear bond strength by placing incrementally two layers of the same composite material. Before applying the second composite layer, the first increment's bonding site was treated as follows: grinding with 1,000-grit silicon-carbide (SiC) abrasive paper, or treatment with ethanol or with water-spray. The inhibition depth was lowest (11.6 μm) for water-sprayed Silorane and greatest (22.9 μm) for the water-sprayed short-fiber-reinforced composite. The shear bond strength ranged from 5.8 MPa (ground Silorane) to 36.4 MPa (water-sprayed SupremeXT). The presence of an oxygen inhibition layer enhanced the interlayer shear bond strength of all investigated materials, but its absence resulted in cohesive and mixed failures only with the short-fiber-reinforced composite. Thus, more durable adhesion with short-fiber-reinforced composite is expected. © 2014 Eur J Oral Sci.

Ideas on Multi-layer Dialogue Management for Multi-party, Multi-conversation, Multi-modal Communication (Extended Abstract of Invited Talk)

National Research Council Canada - National Science Library

Traum, David R

2006-01-01

.... On the other hand, the full spectrum of communication between interacting agents includes cases in which multiple segments of conversation can be interleaved with other, sometimes unrelated actions and events (e.g., a cocktail party...

Communicating. Supervising: Communication. The Choice Series #60. A Self Learning Opportunity.

Science.gov (United States)

Lane, Steven

This student guide is intended to assist persons employed as supervisors in developing communication skills. Discussed in the first two sections are the nature of communication (communication skills and processes and planning communications) and the skills of communication (writing, speaking, and behavioral skills). Each of these sections contains…

Selective layer disordering in III-nitrides with a capping layer

Science.gov (United States)

Wierer, Jr., Jonathan J.; Allerman, Andrew A.

2016-06-14

Selective layer disordering in a doped III-nitride superlattice can be achieved by depositing a dielectric capping layer on a portion of the surface of the superlattice and annealing the superlattice to induce disorder of the layer interfaces under the uncapped portion and suppress disorder of the interfaces under the capped portion. The method can be used to create devices, such as optical waveguides, light-emitting diodes, photodetectors, solar cells, modulators, laser, and amplifiers.

A learning rule for very simple universal approximators consisting of a single layer of perceptrons.

Science.gov (United States)

Auer, Peter; Burgsteiner, Harald; Maass, Wolfgang

2008-06-01

One may argue that the simplest type of neural networks beyond a single perceptron is an array of several perceptrons in parallel. In spite of their simplicity, such circuits can compute any Boolean function if one views the majority of the binary perceptron outputs as the binary output of the parallel perceptron, and they are universal approximators for arbitrary continuous functions with values in [0,1] if one views the fraction of perceptrons that output 1 as the analog output of the parallel perceptron. Note that in contrast to the familiar model of a "multi-layer perceptron" the parallel perceptron that we consider here has just binary values as outputs of gates on the hidden layer. For a long time one has thought that there exists no competitive learning algorithm for these extremely simple neural networks, which also came to be known as committee machines. It is commonly assumed that one has to replace the hard threshold gates on the hidden layer by sigmoidal gates (or RBF-gates) and that one has to tune the weights on at least two successive layers in order to achieve satisfactory learning results for any class of neural networks that yield universal approximators. We show that this assumption is not true, by exhibiting a simple learning algorithm for parallel perceptrons - the parallel delta rule (p-delta rule). In contrast to backprop for multi-layer perceptrons, the p-delta rule only has to tune a single layer of weights, and it does not require the computation and communication of analog values with high precision. Reduced communication also distinguishes our new learning rule from other learning rules for parallel perceptrons such as MADALINE. Obviously these features make the p-delta rule attractive as a biologically more realistic alternative to backprop in biological neural circuits, but also for implementations in special purpose hardware. We show that the p-delta rule also implements gradient descent-with regard to a suitable error measure

Digital Marketing Communication

OpenAIRE

Margherita Corniani

2006-01-01

Digital marketing communication is directed to profiled targets, which are active in the communication process. Every communication flow can ask for an information answer from the market. This opportunity grants immediate feed-backs and feed-forwards, so that digital communication can be easily and cheaply measured; digital communication flows are diffused at costs that are getting lower and lower, but it asks specialized and deep competences to communication managers. The ease in the flowing...

Communication in organization

OpenAIRE

Zajíc, Jaroslav

2009-01-01

Communication is one of the most discussed themes of today and its significance is ever growing. Most often, communication is divided in verbal and nonverbal. It depends if the content of the communicated message is put across in words or not. Every person uses his or her communication style in the contact with others which is different in each situation. The art of communication is the ground not only in everyday life but also in employment. Every organization is a place where communication ...

Communicating in Collectivistic Culture: Relationship between Interdependent Self-Construal and Cooperative Communication in Cross-Cultural Communication Model

Directory of Open Access Journals (Sweden)

Hoo Pin Lick Soo

2017-01-01

Full Text Available This concept paper proposes that when companies have expanded their business and operation throughout the Asian countries, the success or failure of a company abroad depends on how effectively its business negotiators can apply their cross-cultural communication skills in a new cultural environment. At the forefront of this change is interdependent self-construal, which stands as communication medium on interaction goals (international business negotiation outcome in collectivistic culture. The international trade may bring about a lot in terms of cross-cultural communication and international business negotiation, but adopting cooperative communication in the international business negotiations will create more integrative agreements between the international business negotiators. Many scholars believe that if both parties have similarities in communication styles, it will lead to positive interaction (cooperative communication that contributes to cooperation and influences the interaction goals (negotiation outcome. This paper offers critical insight into the theoretical link between interdependent selfconstrual and interaction goals. The proposed cross-cultural communication model uses interdependent self-construal and cooperative communication to understand when collectivistic business negotiators develop relationships that promotes positive interaction goals (negotiation outcome.

Layer-by-layer-assembled healable antifouling films.

Science.gov (United States)

Chen, Dongdong; Wu, Mingda; Li, Bochao; Ren, Kefeng; Cheng, Zhongkai; Ji, Jian; Li, Yang; Sun, Junqi

2015-10-21

Healable antifouling films are fabricated by the exponential layer-by-layer assembly of PEGylated branched poly(ethylenimine) and hyaluronic acid followed by post-crosslinking. The antifouling function originates from the grafted PEG and the extremely soft nature of the films. The rapid and multiple healing of damaged antifouling functions caused by cuts and scratches can be readily achieved by immersing the films in normal saline solution. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Informatics, Culture and Communication in three aspects-communication styles

Institute of Scientific and Technical Information of China (English)

WANG Jing; WANG Yun

2013-01-01

With the development of business among China, Indian and Australia, people pay more attention to communication chan⁃nels and cross-cultural business ethics and methods as well as cultural, religious and dietary issues that may impact on successful communication. This article talks about cross communication awareness and methods for improving cross cultural communication based on author’s working experience in a firm in Sydney (Australia) that exports foodstuffs to a number of countries in Asia.

The Layer 1 / Layer 2 readout upgrade for the ATLAS Pixel Detector

CERN Document Server

Mullier, Geoffrey; The ATLAS collaboration

2016-01-01

The Pixel Detector of the ATLAS experiment has shown excellent performance during the whole Run-1 of the Large Hadron Collider (LHC). The increase of instantaneous luminosity foreseen during the LHC Run 2, will lead to an increased detector occupancy that is expected to saturate the readout links of the outermost layers of the pixel detector: Layers 1 and 2. To ensure a smooth data taking under such conditions, the read out system of the recently installed fourth innermost pixel layer, the Insertable B-Layer, was modified to accomodate the needs of the older detector. The Layer 2 upgrade installation took place during the 2015 winter shutdown, with the Layer 1 installation scheduled for 2016. A report of the successful installation, together with the design of novel dedicated optical to electrical converters and the software and firmware updates will be presented.

Chitosan-Recombinamer Layer-by-Layer Coatings for Multifunctional Implants

Directory of Open Access Journals (Sweden)

Jeevan Prasaad Govindharajulu

2017-02-01

Full Text Available The main clinical problems for dental implants are (1 formation of biofilm around the implant—a condition known as peri-implantitis and (2 inadequate bone formation around the implant—lack of osseointegration. Therefore, developing an implant to overcome these problems is of significant interest to the dental community. Chitosan has been reported to have good biocompatibility and anti-bacterial activity. An osseo-inductive recombinant elastin-like biopolymer (P-HAP, that contains a peptide derived from the protein statherin, has been reported to induce biomineralization and osteoblast differentiation. In this study, chitosan/P-HAP bi-layers were built on a titanium surface using a layer-by-layer (LbL assembly technique. The difference in the water contact angle between consecutive layers, the representative peaks in diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS, X-ray photoelectron spectroscopy (XPS, and the changes in the topography between surfaces with a different number of bi-layers observed using atomic force microscopy (AFM, all indicated the successful establishment of chitosan/P-HAP LbL assembly on the titanium surface. The LbL-modified surfaces showed increased biomineralization, an appropriate mouse pre-osteoblastic cell response, and significant anti-bacterial activity against Streptococcus gordonii, a primary colonizer of tissues in the oral environment

Improving nurse-patient communication with patients with communication impairments: hospital nurses' views on the feasibility of using mobile communication technologies.

Science.gov (United States)

Sharpe, Bridget; Hemsley, Bronwyn

2016-05-01

Nurses communicating with patients who are unable to speak often lack access to tools and technologies to support communication. Although mobile communication technologies are ubiquitous, it is not known whether their use to support communication is feasible on a busy hospital ward. The aim of this study was to determine the views of hospital nurses on the feasibility of using mobile communication technologies to support nurse-patient communication with individuals who have communication impairments. This study involved an online survey followed by a focus group, with findings analyzed across the two data sources. Nurses expected that mobile communication devices could benefit patient care but lacked access to these devices, encountered policies against use, and held concerns over privacy and confidentiality. The use of mobile communication technologies with patients who have communication difficulties is feasible and may lead to improvements in communication and care, provided environmental barriers are removed and facilitators enhanced. Copyright © 2015 Elsevier Inc. All rights reserved.

INTERCULTURAL COMMUNICATION PATTERNS AND LANGUAGE USE IN COMPUTER MEDIATED-COMMUNICATION

Directory of Open Access Journals (Sweden)

Adriana Teodorescu

2012-11-01

Full Text Available This paper aims at analyzing the degree to which intercultural communication patterns are embedded in computer-mediated communication. Drawing on Hall’s and Hofstede’s intercultural communication dimensions, this study evaluates empirically high-versus-low context cultural orientations as reflected in the electronic medium, namely the blog, in three different cultures. Cultural variation is also analyzed in linguistic features and communication style in a synchronous mode of communication, by investigating data from several popular blogs from Japan, Germany and Italy.

Towards Reliable and Energy-Efficient Incremental Cooperative Communication for Wireless Body Area Networks.

Science.gov (United States)

Yousaf, Sidrah; Javaid, Nadeem; Qasim, Umar; Alrajeh, Nabil; Khan, Zahoor Ali; Ahmed, Mansoor

2016-02-24

In this study, we analyse incremental cooperative communication for wireless body area networks (WBANs) with different numbers of relays. Energy efficiency (EE) and the packet error rate (PER) are investigated for different schemes. We propose a new cooperative communication scheme with three-stage relaying and compare it to existing schemes. Our proposed scheme provides reliable communication with less PER at the cost of surplus energy consumption. Analytical expressions for the EE of the proposed three-stage cooperative communication scheme are also derived, taking into account the effect of PER. Later on, the proposed three-stage incremental cooperation is implemented in a network layer protocol; enhanced incremental cooperative critical data transmission in emergencies for static WBANs (EInCo-CEStat). Extensive simulations are conducted to validate the proposed scheme. Results of incremental relay-based cooperative communication protocols are compared to two existing cooperative routing protocols: cooperative critical data transmission in emergencies for static WBANs (Co-CEStat) and InCo-CEStat. It is observed from the simulation results that incremental relay-based cooperation is more energy efficient than the existing conventional cooperation protocol, Co-CEStat. The results also reveal that EInCo-CEStat proves to be more reliable with less PER and higher throughput than both of the counterpart protocols. However, InCo-CEStat has less throughput with a greater stability period and network lifetime. Due to the availability of more redundant links, EInCo-CEStat achieves a reduced packet drop rate at the cost of increased energy consumption.

Communications architecture for an electric company, European utility communications architecture, EURUCA

Energy Technology Data Exchange (ETDEWEB)

Uuspaeae, P [VTT Energy, Espoo (Finland)

1998-08-01

The scope of this research is integration and interoperability of various information systems and data communications for electric utilities. Utility Communication Architecture refers to an overall view of the communications needs and communication systems in an electric utility. The objective is to define and specify suitable and compatible communications procedures within the Utility and also to outside parties

Human Bond Communication

DEFF Research Database (Denmark)

Prasad, Ramjee

2016-01-01

Modern dexterous communication technology is progressively enabling humans to communicate their information through them with speech (aural) and media (optical) as underpinning essence. Humans realize this kind of aural and optical information by their optical and auditory senses. However, due...... to certain constraints, the ability to incorporate the other three sensory features namely, olfactory, gustatory, and tactile are still far from reality. Human bond communication is a novel concept that incorporates olfactory, gustatory, and tactile that will allow more expressive and holistic sensory...... information exchange through communication techniques for more human sentiment centric communication. This concept endorses the need of inclusion of other three senses and proposes an innovative approach of holistic communication for future communication network....

“We definitely need an audience”: experiences of Twitter, Twitter networks and tweet content in adults with severe communication disabilities who use augmentative and alternative communication (AAC)

Science.gov (United States)

Hemsley, Bronwyn; Dann, Stephen; Palmer, Stuart; Allan, Meredith; Balandin, Susan

2015-01-01

Abstract Purpose: The aim of this study was to investigate the Twitter experiences of adults with severe communication disabilities who use augmentative and alternative communication (AAC) to inform Twitter training and further research on the use of Twitter in populations with communication disabilities. Method: This mixed methods research included five adults with severe communication disabilities who use AAC. It combined (a) quantitative analysis of Twitter networks and (b) manual coding of tweets with (c) narrative interviews with participants on their Twitter experiences and results. Results: The five participants who used AAC and Twitter were diverse in their patterns and experiences of using Twitter. Twitter networks reflected interaction with a close-knit network of people rather than with the broader publics on Twitter. Conversational, Broadcast and Pass Along tweets featured most prominently, with limited use of News or Social Presence tweets. Tweets appeared mostly within each participant's micro- or meso-structural layers of Twitter. Conclusions: People who use AAC report positive experiences in using Twitter. Obtaining help in Twitter, and engaging in hashtag communities facilitated higher frequency of tweets and establishment of Twitter networks. Results reflected an inter-connection of participant Twitter networks that might form part of a larger as yet unexplored emergent community of people who use AAC in Twitter.Implications for RehabilitationTwitter can be used as an important vehicle for conversation and a forum for people with communication disabilities to exchange information and participate socially in online communities.It is important that information and resources relating to the effective use of Twitter for a range of purposes are made available to people with communication disabilities who wish to take up or maintain use of Twitter.People with communication disabilities might benefit from support in using Twitter to meet their goals

Evaluating the transport layer of the ALFA framework for the Intel(®) Xeon Phi(™) Coprocessor

OpenAIRE

Santogidis, Aram; Hirstius, Andreas; Lalis, Spyros

2015-01-01

The ALFA framework supports the software development of major High Energy Physics experiments. As part of our research effort to optimize the transport layer of ALFA, we focus on profiling its data transfer performance for inter-node communication on the Intel Xeon Phi Coprocessor. In this article we present the collected performance measurements with the related analysis of the results. The optimization opportunities that are discovered, help us to formulate the future plans of enabling high...

Advanced communication methods developed for nuclear data communication applications

International Nuclear Information System (INIS)

Tiwari, Akash; Tiwari, Railesha; Tiwari, S.S.; Panday, Lokesh; Suri, Nitin; Takle, Tarun Rao; Jain, Sanjeev; Gupta, Rishi; Sharma, Dipeeka; Takle, Rahul Rao; Gautam, Rajeev; Bhargava, Vishal; Arora, Himanshu; Agarwal, Ankur; Rupesh; Chawla, Mohit; Sethi, Amardeep Singh; Gupta, Mukesh; Gupta, Ankit; Verma, Neha; Sood, Nitin; Singh, Sunil; Agarwal, Chandresh

2004-01-01

We conducted various experiments and tested data communications methods that may be useful for various applications in nuclear industries. We explored the following areas. I. Scientific data communication among scientists within the laboratory and inter-laboratory data exchange. 2.Data from sensors from remote and wired sensors. 3.Data from multiple sensors with small zone. 4.Data from single or multiple sensors from distances above 100 m and less than 10 km. No any single data communication method was found to be the best solution for nuclear applications and multiple modes of communication were found to be advantageous than any single mode of data communication. Network of computers in the control room and in between laboratories connected with optical fiber or an isolated Ethernet coaxial LAN was found to be optimum. Information from multiple analog process sensors in smaller zones like reactor building and laboratories on 12C LAN and short-range wireless LAN were found to be advantageous. Within the laboratory sensor data network of 12C was found to be cost effective and wireless LAN was comparatively expansive. Within a room infrared optical LAN and FSK wireless LAN were found to be highly useful in making the sensors free from wires. Direct sensor interface on FSK wireless link were found to be fast accurate, cost effective over large distance data communication. Such links are the only way to communicate from sea boy and balloons hardware. 1-wire communication network of Dallas Semiconductor USA for weather station data communication Computer to computer communication using optical LAN links has been tried, temperature pressure, humidity, ionizing radiation, generator RPM and voltage and various other analog signals were also transported o FSK optical and wireless links. Multiple sensors needed a dedicated data acquisition system and wireless LAN for data telemetry. (author)

Ripple Communication.

Science.gov (United States)

Wilcox, R. Stimson

1980-01-01

Discusses how surface-dwelling animals use the water surface as a mode of communication by making ripple signals while they swim about. Provides information about surfaces and surface waves, ripple communication in water striders, ripple signal characteristics, sensing and orienting, other modes of communication, and evolution of ripple…

Asymmetric temporal integration of layer 4 and layer 2/3 inputs in visual cortex.

Science.gov (United States)

Hang, Giao B; Dan, Yang

2011-01-01

Neocortical neurons in vivo receive concurrent synaptic inputs from multiple sources, including feedforward, horizontal, and feedback pathways. Layer 2/3 of the visual cortex receives feedforward input from layer 4 and horizontal input from layer 2/3. Firing of the pyramidal neurons, which carries the output to higher cortical areas, depends critically on the interaction of these pathways. Here we examined synaptic integration of inputs from layer 4 and layer 2/3 in rat visual cortical slices. We found that the integration is sublinear and temporally asymmetric, with larger responses if layer 2/3 input preceded layer 4 input. The sublinearity depended on inhibition, and the asymmetry was largely attributable to the difference between the two inhibitory inputs. Interestingly, the asymmetric integration was specific to pyramidal neurons, and it strongly affected their spiking output. Thus via cortical inhibition, the temporal order of activation of layer 2/3 and layer 4 pathways can exert powerful control of cortical output during visual processing.

Climate change communication: what can we learn from communication theory?

DEFF Research Database (Denmark)

Ballantyne, Anne Gammelgaard

2016-01-01

the field of communication theory are highlighted and discussed in the context of communicating climate change. Rooted in the interaction paradigm, the article proposes a meta‐theoretical framework that conceptualizes communication as a constitutive process of producing and reproducing shared meanings...... as a theoretical construct. In some instances, communication theory appears reduced to an ‘ad hoc’ toolbox, from which theories are randomly picked to provide studies with a fitting framework. Inspired by the paradigm shift from transmission to interaction within communication theory, potential lessons from...

Hybrid inorganic–organic superlattice structures with atomic layer deposition/molecular layer deposition

Energy Technology Data Exchange (ETDEWEB)

Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit, E-mail: maarit.karppinen@aalto.fi [Department of Chemistry, Aalto University, FI-00076 Aalto (Finland)

2014-01-15

A combination of the atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques is successfully employed to fabricate thin films incorporating superlattice structures that consist of single layers of organic molecules between thicker layers of ZnO. Diethyl zinc and water are used as precursors for the deposition of ZnO by ALD, while three different organic precursors are investigated for the MLD part: hydroquinone, 4-aminophenol and 4,4′-oxydianiline. The successful superlattice formation with all the organic precursors is verified through x-ray reflectivity studies. The effects of the interspersed organic layers/superlattice structure on the electrical and thermoelectric properties of ZnO are investigated through resistivity and Seebeck coefficient measurements at room temperature. The results suggest an increase in carrier concentration for small concentrations of organic layers, while higher concentrations seem to lead to rather large reductions in carrier concentration.

Non-electronic communication aids for people with complex communication needs.

Science.gov (United States)

Iacono, Teresa; Lyon, Katie; West, Denise

2011-10-01

Non-electronic communication aids provide one form of augmentative and alternative communication (AAC) for people with complex communication needs. The aim here was to explore non-electronic communication aids as one AAC option and research challenges. This aim was addressed by reviewing funding for the provision of AAC systems, data from an Australian pilot project providing non-electronic communication aids, an audit of aided AAC published studies (2000-2009), and discussion of the review literature. Combined, these sources indicate that although there is great demand for non-electronic communication aids, funding schemes, both in Australia and internationally, have focused on electronic communication aids. Such funding has usually failed to meet the total device costs and has not provided for adequate speech-language pathology support. Data from the pilot indicated the demand for non-electronic communication aids, and patterns suggest potential factors that govern the types selected. Despite the high demand for non-electronic aids, the research literature has tended to focus on electronic communication aids, including within intervention studies and addressing design features and long-term outcomes. Concerns about ensuring that AAC systems are chosen according to the assessed needs of individuals are discussed within the context of limitations in outcomes research and appropriate outcome measures.

Multimedia Astronomy Communication: Effectively Communicate Astronomy to the Desired Audience

Science.gov (United States)

Star Cartier, Kimberly Michelle; Wright, Jason

2017-01-01

A fundamental aspect of our jobs as scientists is communicating our work to others. In this, the field of astronomy holds the double-edged sword of ubiquitous fascination: the topic has been of interest to nearly the entire global population at some point in their lives, yet the learning curve is steep within any subfield and rife with difficult-to-synthesize details. Compounding this issue is the ever-expanding array of methods to reach people in today's Communications Era. Each communication medium has its own strengths and weaknesses, is appropriate in different situations, and requires its own specific skillset in order to maximize its functionality. Despite this, little attention is given to training astronomers in effective communication techniques, often relying on newcomers to simply pick up the ability by mimicking others and assuming that a firm grasp on the subject matter will make up for deficiencies in communication theory. This can restrict astronomers to a narrow set of communication methods, harming both the communicators and the audience who may struggle to access the information through those media.Whether writing a research paper to academic peers or giving an astronomy talk to a pubic audience, successfully communicating a scientific message requires more than just an expert grasp on the topic. A communicator must understand the makeup and prior knowledge of the desired audience, be able to break down the salient points of the topic into pieces that audience can digest, select and maximize upon a medium to deliver the message, and frame the message in a way that hooks the audience and compels further interest. In this work we synthesize the requirements of effective astronomy communication into a few key questions that every communicator needs to answer. We then discuss some of the most common media currently used to communicate astronomy, give both effective and poor examples of utilizing these media to communicate astronomy, and provide key

Layer-specific morphological and molecular differences in neocortical astrocytes and their dependence on neuronal layers.

Science.gov (United States)

Lanjakornsiripan, Darin; Pior, Baek-Jun; Kawaguchi, Daichi; Furutachi, Shohei; Tahara, Tomoaki; Katsuyama, Yu; Suzuki, Yutaka; Fukazawa, Yugo; Gotoh, Yukiko

2018-04-24

Non-pial neocortical astrocytes have historically been thought to comprise largely a nondiverse population of protoplasmic astrocytes. Here we show that astrocytes of the mouse somatosensory cortex manifest layer-specific morphological and molecular differences. Two- and three-dimensional observations revealed that astrocytes in the different layers possess distinct morphologies as reflected by differences in cell orientation, territorial volume, and arborization. The extent of ensheathment of synaptic clefts by astrocytes in layer II/III was greater than that by those in layer VI. Moreover, differences in gene expression were observed between upper-layer and deep-layer astrocytes. Importantly, layer-specific differences in astrocyte properties were abrogated in reeler and Dab1 conditional knockout mice, in which neuronal layers are disturbed, suggesting that neuronal layers are a prerequisite for the observed morphological and molecular differences of neocortical astrocytes. This study thus demonstrates the existence of layer-specific interactions between neurons and astrocytes, which may underlie their layer-specific functions.

A New Digital Watermarking Method for Data Integrity Protection in the Perception Layer of IoT

Directory of Open Access Journals (Sweden)

Guoyin Zhang

2017-01-01

Full Text Available Since its introduction, IoT (Internet of Things has enjoyed vigorous support from governments and research institutions around the world, and remarkable achievements have been obtained. The perception layer of IoT plays an important role as a link between the IoT and the real world; the security has become a bottleneck restricting the further development of IoT. The perception layer is a self-organizing network system consisting of various resource-constrained sensor nodes through wireless communication. Accordingly, the costly encryption mechanism cannot be applied to the perception layer. In this paper, a novel lightweight data integrity protection scheme based on fragile watermark is proposed to solve the contradiction between the security and restricted resource of perception layer. To improve the security, we design a position random watermark (PRW strategy to calculate the embedding position by temporal dynamics of sensing data. The digital watermark is generated by one-way hash function SHA-1 before embedding to the dynamic computed position. In this way, the security vulnerabilities introduced by fixed embedding position can not only be solved effectively, but also achieve zero disturbance to the data. The security analysis and simulation results show that the proposed scheme can effectively ensure the integrity of the data at low cost.

Communication Speaks

Science.gov (United States)

Kinman, Robin Lynn

2010-01-01

When the author recently turned her attention to the National Council of Teachers of Mathematics (NCTM) "Principles and Standards," she was startled to see communication as key. She adjusted her teaching to meet the NCTM Communication Standard and promote communication in her classroom by providing a safe environment, developing discourse and…

Cultural Communications.

Science.gov (United States)

Armas, Jose

It is too often taken for granted that the communication process with culturally different children takes place as readily as it might with children from Anglo cultures. Most teachers receive training in verbal and formal communication skills; children come to school with nonverbal and informal communication skills. This initially can create…

Evaluating Internal Communication: The ICA Communication Audit.

Science.gov (United States)

Goldhaber, Gerald M.

1978-01-01

The ICA Communication Audit is described in detail as an effective measurement procedure that can help an academic institution to evaluate its internal communication system. Tools, computer programs, analysis, and feedback procedures are described and illustrated. (JMF)

A Model of Internal Communication in Adaptive Communication Systems.

Science.gov (United States)

Williams, M. Lee

A study identified and categorized different types of internal communication systems and developed an applied model of internal communication in adaptive organizational systems. Twenty-one large organizations were selected for their varied missions and diverse approaches to managing internal communication. Individual face-to-face or telephone…

Boosting water oxidation layer-by-layer.

Science.gov (United States)

Hidalgo-Acosta, Jonnathan C; Scanlon, Micheál D; Méndez, Manuel A; Amstutz, Véronique; Vrubel, Heron; Opallo, Marcin; Girault, Hubert H

2016-04-07

Electrocatalysis of water oxidation was achieved using fluorinated tin oxide (FTO) electrodes modified with layer-by-layer deposited films consisting of bilayers of negatively charged citrate-stabilized IrO2 NPs and positively charged poly(diallyldimethylammonium chloride) (PDDA) polymer. The IrO2 NP surface coverage can be fine-tuned by controlling the number of bilayers. The IrO2 NP films were amorphous, with the NPs therein being well-dispersed and retaining their as-synthesized shape and sizes. UV/vis spectroscopic and spectro-electrochemical studies confirmed that the total surface coverage and electrochemically addressable surface coverage of IrO2 NPs increased linearly with the number of bilayers up to 10 bilayers. The voltammetry of the modified electrode was that of hydrous iridium oxide films (HIROFs) with an observed super-Nernstian pH response of the Ir(III)/Ir(IV) and Ir(IV)-Ir(IV)/Ir(IV)-Ir(V) redox transitions and Nernstian shift of the oxygen evolution onset potential. The overpotential of the oxygen evolution reaction (OER) was essentially pH independent, varying only from 0.22 V to 0.28 V (at a current density of 0.1 mA cm(-2)), moving from acidic to alkaline conditions. Bulk electrolysis experiments revealed that the IrO2/PDDA films were stable and adherent under acidic and neutral conditions but degraded in alkaline solutions. Oxygen was evolved with Faradaic efficiencies approaching 100% under acidic (pH 1) and neutral (pH 7) conditions, and 88% in alkaline solutions (pH 13). This layer-by-layer approach forms the basis of future large-scale OER electrode development using ink-jet printing technology.

Layer-by-layer self-assembly of polyimide precursor/layered double hydroxide ultrathin films

International Nuclear Information System (INIS)

Chen Dan; Huang Shu; Zhang Chao; Wang Weizhi; Liu Tianxi

2010-01-01

The layer-by-layer (LBL) self-assembly has been extensively used as a simple and effective method for the preparation of polyelectrolyte multilayer films. In this work, we utilized this unique method to prepare polyimide precursor/layered double hydroxide (LDH) ultrathin films. Well-crystallized Co-Al-CO 3 LDH and subsequent anion exchanged Co-Al-NO 3 LDH were prepared and characterized by scanning electron microscopy and X-ray diffraction (XRD). By vigorous shaking of the as-prepared Co-Al-NO 3 LDH, positively charged and exfoliated LDH nanosheets were obtained. Atomic force microscopy and XRD investigations indicated the delamination of LDH nanosheets. The precursor of polyimide, poly(amic acid) tertiary amine salt (PAS) was prepared by the polycondensation of dianhydride and diamine, and subsequent amine salt formation. By using the LBL method, heterogeneous ultrathin films of PAS and LDH were prepared. The formation of the ordered nanostructured assemblies was confirmed by the progressive enhancement of UV absorbance and the XRD results.

Double layers in space

International Nuclear Information System (INIS)

Carlqvist, P.

1982-07-01

For more than a decade it has been realised that electrostatic double layers are likely to occur in space. We briefly discuss the theoretical background of such double layers. Most of the paper is devoted to an account of the observational evidence for double layers in the ionosphere and magnetosphere of the Earth. Several different experiments are reviewed including rocket and satellite measurements and ground based observations. It is concluded that the observational evidence for double layers in space is very strong. The experimental results indicate that double layers with widely different properties may exist in space. (Author)

Double layers in space

International Nuclear Information System (INIS)

Carlqvist, P.

1982-01-01

For more than a decade it has been realised that electrostatic double layers are likely to occur in space. The author briefly discusses the theoretical background of such double layers. Most of the paper is devoted to an account of the observational evidence for double layers in the ionosphere and magnetosphere of the Earth. Several different experiments are reviewed including rocket and satellite measurements and ground based observations. It is concluded that the observational evidence for double layers in space is very strong. The experimental results indicate that double layers with widely different properties may exist in space. (Auth.)

The Communication Audit: A Framework for Teaching Management Communication.

Science.gov (United States)

Shelby, Annette N.; Reinsch, N. Lamar, Jr.

1996-01-01

Describes a communication audit project used in a graduate-level management communication course. Reviews literature concerning communication audits, explains why and how an audit project is used in the author's classes, and describes specific audit-related assignments. Concludes that, although a challenging assignment, the audit is worthwhile.…

Proactive Parent Communication.

Science.gov (United States)

Babcock, Sharel; Backlund, Judy

2001-01-01

Presents examples of teacher-parent interactions designed to help teachers communicate with parents. The scenarios involve a teacher communicating with parents about a struggling student, a teacher communicating with parents about a student's behavior problems, and a teacher attempting to communicate with a confrontational parent. Teacher prompts…

Implementation of olfactory bulb glomerular-layer computations in a digital neurosynaptic core.

Science.gov (United States)

Imam, Nabil; Cleland, Thomas A; Manohar, Rajit; Merolla, Paul A; Arthur, John V; Akopyan, Filipp; Modha, Dharmendra S

2012-01-01

We present a biomimetic system that captures essential functional properties of the glomerular layer of the mammalian olfactory bulb, specifically including its capacity to decorrelate similar odor representations without foreknowledge of the statistical distributions of analyte features. Our system is based on a digital neuromorphic chip consisting of 256 leaky-integrate-and-fire neurons, 1024 × 256 crossbar synapses, and address-event representation communication circuits. The neural circuits configured in the chip reflect established connections among mitral cells, periglomerular cells, external tufted cells, and superficial short-axon cells within the olfactory bulb, and accept input from convergent sets of sensors configured as olfactory sensory neurons. This configuration generates functional transformations comparable to those observed in the glomerular layer of the mammalian olfactory bulb. Our circuits, consuming only 45 pJ of active power per spike with a power supply of 0.85 V, can be used as the first stage of processing in low-power artificial chemical sensing devices inspired by natural olfactory systems.

The human communication space towards I-centric communications

CERN Document Server

Arbanowski, S; Steglich, S; Popescu-Zeletin, R

2001-01-01

A variety of concepts for service integration and corresponding systems have been developed. On one hand, they aim for the interworking and integration of classical telecommunications and data communications services. On the other, they are focusing on universal service access from a variety of end-user systems. Many of the technical problems, resulting from service integration and service personalisation, have been solved. However, all these systems are driven by the concept of providing several technologies to users by keeping the peculiarity of each service. Looking at human communication behaviour and communication space, it is obvious that human beings interact habitually in a set of contexts with their environment. The individual information preferences and needs, persons to interact with, and the set of devices controlled by each individual define their personal communication space. Following this view, a new approach is to build communication systems not on the basis of specific technologies, but on t...

Distributed communication: Implications of cultural-historical activity theory (CHAT) for communication disorders.

Science.gov (United States)

Hengst, Julie A

2015-01-01

This article proposes distributed communication as a promising theoretical framework for building supportive environments for child language development. Distributed communication is grounded in an emerging intersection of cultural-historical activity theory (CHAT) and theories of communicative practices that argue for integrating accounts of language, cognition and culture. The article first defines and illustrates through selected research articles, three key principles of distributed communication: (a) language and all communicative resources are inextricably embedded in activity; (b) successful communication depends on common ground built up through short- and long-term histories of participation in activities; and (c) language cannot act alone, but is always orchestrated with other communicative resources. It then illustrates how these principles are fully integrated in everyday interactions by drawing from my research on Cindy Magic, a verbal make-believe game played by a father and his two daughters. Overall, the research presented here points to the remarkably complex communicative environments and sophisticated forms of distributed communication children routinely engage in as they interact with peer and adult communication partners in everyday settings. The article concludes by considering implications of these theories for, and examples of, distributed communication relevant to clinical intervention. Readers will learn about (1) distributed communication as a conceptual tool grounded in an emerging intersection of cultural-historical activity theory and theories of communicative practices and (2) how to apply distributed communication to the study of child language development and to interventions for children with communication disorders. Copyright © 2015 Elsevier Inc. All rights reserved.

Stereotypes Communication

Science.gov (United States)

Zhang, Shuli; Deng, Dongyuan

2009-01-01

We live in a world, which is becoming a Global Village in which information and communication attract people's attention more than ever before. Our desire to communicate with strangers and our relationships with them depend on the degree to which we are effective in communicating with them. There are so many factors restricting or improving…

Topotactic condensation of layer silicates with ferrierite-type layers forming porous tectosilicates.

Science.gov (United States)

Marler, B; Wang, Y; Song, J; Gies, H

2014-07-21

Five different hydrous layer silicates (HLSs) containing fer layers (ferrierite-type layers) were obtained by hydrothermal syntheses from mixtures of silicic acid, water and tetraalkylammonium/tetraalkylphosphonium hydroxides. The organic cations had been added as structure directing agents (SDA). A characteristic feature of the structures is the presence of strong to medium strong hydrogen bonds between the terminal silanol/siloxy groups of neighbouring layers. The five-layered silicates differ chemically only with respect to the organic cations. Structurally, they differ with respect to the arrangement of the fer layers relative to each other, which is distinct for every SDA-fer-layer system. RUB-20 (containing tetramethylammonium) and RUB-40 (tetramethylphosphonium) are monoclinic with stacking sequence AAA and shift vectors between successive layers 1a0 + 0b0 + 0.19c0 and 1a0 + 0b0 + 0.24c0, respectively. RUB-36 (diethyldimethylammonium), RUB-38 (methyltriethylammonium) and RUB-48 (trimethylisopropylammonium) are orthorhombic with stacking sequence ABAB and shift vectors 0.5a0 + 0b0± 0.36c0, 0.5a0 + 0b0 + 0.5c0 and 0.5a0 + 0b0± 0.39c0, respectively. Unprecedented among the HLSs, two monoclinic materials are made up of fer layers which possess a significant amount of ordered defects within the layer. The ordered defects involve one particular Si-O-Si bridge which is, to a fraction of ca. 50%, hydrolyzed to form nests of two ≡Si-OH groups. When heated to 500-600 °C in air, the HLSs condense to form framework silicates. Although all layered precursors were moderately to well ordered, the resulting framework structures were of quite different crystallinity. The orthorhombic materials RUB-36, -38 and -48, general formula SDA4Si36O72(OH)4, which possess very strong hydrogen bonds (d[O···O] ≈ 2.4 Å), transform into a fairly or well ordered CDO-type silica zeolite RUB-37. The monoclinic materials RUB-20 and -40, general formula SDA2Si18O36(OH)2OH, possessing

Hybrid window layer for photovoltaic cells

Science.gov (United States)

Deng, Xunming

2010-02-23

A novel photovoltaic solar cell and method of making the same are disclosed. The solar cell includes: at least one absorber layer which could either be a lightly doped layer or an undoped layer, and at least a doped window-layers which comprise at least two sub-window-layers. The first sub-window-layer, which is next to the absorber-layer, is deposited to form desirable junction with the absorber-layer. The second sub-window-layer, which is next to the first sub-window-layer, but not in direct contact with the absorber-layer, is deposited in order to have transmission higher than the first-sub-window-layer.

Aesthetic Communication

DEFF Research Database (Denmark)

Thyssen, Ole

2012-01-01

Based on Niklas Luhmann's systems theory, aesthetics is defined as a manner of reinforcing the connectivity, or Anschlusswert, of communication. Without changing the content, a message can be made more attractive, strengthening the receiver's willingness to be attentive and accepting. As communic......Based on Niklas Luhmann's systems theory, aesthetics is defined as a manner of reinforcing the connectivity, or Anschlusswert, of communication. Without changing the content, a message can be made more attractive, strengthening the receiver's willingness to be attentive and accepting....... As communication inevitably makes use of a sensuous medium, such as light or sound, all communication has an aesthetic dimension. In the 19th Century, an important distinction was made between pure and applied art, following Immanuel Kant's separation of theory of knowledge, moral theory and aesthetic theory....... Whereas pure art is produced in order to be observed, applied art has to fulfill practical purposes as well. Modern organizations, defined as systems of communication, may use art works to embellish and define themselves. But they inevitably use applied art as a practical tool in their normal...

Crisis Communication Online

DEFF Research Database (Denmark)

Utz, Sonja; Schultz, Friederike; Glocka, Sandra

2013-01-01

Social media play in today's societies a fundamental role for the negotiation and dynamics of crises. However, classical crisis communication theories neglect the role of the medium and focus mainly on the interplay between crisis type and crisis communication strategy. Building on the recently...... developed “networked crisis communication model” we contrast effects of medium (Facebook vs. Twitter vs. online newspaper) and crisis type (intentional vs. victim) in an online experiment. Using the Fukushima Daiichi nuclear disaster as crisis scenario, we show that medium effects are stronger than...... the effects of crisis type. Crisis communication via social media resulted in a higher reputation and less secondary crisis reactions such as boycotting the company than crisis communication in the newspaper. However, secondary crisis communication, e.g. talking about the crisis communication, was higher...

Preface to the special issue on ;Optical Communications Exploiting the Space Domain;

Science.gov (United States)

Wang, Jian; Yu, Siyuan; Li, Guifang

2018-02-01

The demand for high capacity optical communications will continue to be driven by the exponential growth of global internet traffic. Optical communications are about the exploitation of different physical dimensions of light waves, including complex amplitude, frequency (or wavelength), time, polarization, etc. Conventional techniques such as wavelength-division multiplexing (WDM), time-division multiplexing (TDM) and polarization-division multiplexing (PDM) have almost reached their scalability limits. Space domain is the only known physical dimension left and space-division multiplexing (SDM) seems the only option to further scale the transmission capacity and spectral efficiency of optical communications. In recent years, few-mode fiber (FMF), multi-mode fiber (MMF), multi-core fiber (MCF) and few-mode multi-core fiber (FM-MCF) have been widely explored as promising candidates for fiber-based SDM. The challenges for SDM include efficient (de)multiplexer, amplifiers, and multiple-input multiple-output (MIMO) digital signal processing (DSP) techniques. Photonic integration will also be a key technology to SDM. Meanwhile, free-space and underwater optical communications have also exploited the space domain to increase the transmission capacity and spectral efficiency. The challenges include long-distance transmission limited by propagation loss, divergence, scattering and turbulence. Very recently, helically phased light beams carrying orbital angular momentum (OAM) have also seen potential applications both in free-space, underwater and fiber-based optical communications. Actually, different mode bases such as linearly polarized (LP) modes and OAM modes can be employed for SDM. Additionally, SDM could be used in chip-scale photonic interconnects and data center optical interconnects. Quantum processing exploiting the space domain is of great interest. The information capacity limit and physical layer security in SDM optical communications systems are important

Review of optical wireless communications for data centers

Science.gov (United States)

Arnon, Shlomi

2017-10-01

A data center (DC) is a facility either physical or virtual, for running applications, searching, storage, management and dissemination of information known as cloud computing, which consume a huge amount of energy. A DC includes thousands of servers, communication and storage equipment and a support system including an air conditioning system, security, monitoring equipment and electricity regulator units. Data center operators face the challenges of meeting exponentially increasing demands for network bandwidth without unreasonable increases in operation and infrastructure cost. In order to meet the requirements of moderate increase in operation and infrastructure cost technology, a revolution is required. One way to overcome the shortcomings of traditional static (wired) data center architectures is use of a hybrid network based on fiber and optical wireless communication (OWC) or free space optics (FSO). The OWC link could be deployed on top of the existing cable/fiber network layer, so that live migration could be done easily and dynamically. In that case the network topology is flexible and adapts quickly to changes in traffic, heat distribution, power consumption and characteristics of the applications. In addition, OWC could provide an easy way to maintain and scale up data centers. As a result total cost of ownership could be reduced and the return on investment could be increased. In this talk we will review the main OWC technologies applicable for data centers, indicate how energy could be saved using OWC multichannel communication and discuss the issue of OWC pointing accuracy for data center scenario.

Evaluating the transport layer of the ALFA framework for the Intel® Xeon Phi™ Coprocessor

Science.gov (United States)

Santogidis, Aram; Hirstius, Andreas; Lalis, Spyros

2015-12-01

The ALFA framework supports the software development of major High Energy Physics experiments. As part of our research effort to optimize the transport layer of ALFA, we focus on profiling its data transfer performance for inter-node communication on the Intel Xeon Phi Coprocessor. In this article we present the collected performance measurements with the related analysis of the results. The optimization opportunities that are discovered, help us to formulate the future plans of enabling high performance data transfer for ALFA on the Intel Xeon Phi architecture.

Reducing public communication apprehension by boosting self confidence on communication competence

Directory of Open Access Journals (Sweden)

Eva Rachmi

2012-07-01

Full Text Available Abstrak Latar belakang: Dokter harus kompeten dalam berkomunikasi dengan sesame dokter ata dengan profesi lain. Pada Fakultas Kedokteran Universitas Mulawarman, beberapa mahasiswa cenderung diam pada saat pelatihan komunikasi public, yang tampaknya disebabkan oleh kecemasan saat berkomunikasi. Penelitian ini bertujuan untuk menganalisa kemungkinan ‘kepercayaan diri terhadap kemampuan komunikasi’ dan  ‘ketrampilan berkomunikasi’ sebagai factor resiko terjadinya ‘kecemasan dalam komunikasi publik’ Metode: Penelitian ini dilakukan pada 55 mahasiswa Fakultas Kedokteran Universitas Mulawarman. Kecemasan dalam komunikasi public diukur dengan Personal report of communication apprehension (PRCA-24, kepercayaan diri terhadap kemampuan komunikasi dengan Self perceived communication competence scale (SPCC, ketrampilan berkomunikasi didasarkan pada penilaian instruktur saat program pelatihan komunikasi, Data dianaliasa dengan regresi linear untuk mengidentifikasi factor yang dominan, menggunakan STATA 9.0 Hasil: Hasil penelitian menunjukkan hubungan negative antara kecemasan dalam public komunikasi dengan kepercayaan diri terhadap kemampuan komunikasi (koefisien regresi (KR =-0.13; p=0.000; 95% derajat kepercayaan (DK =-0.20; -0.52. Tetapi, terbukti tidak berhubungan dengan ketrampilan komunikasi (p=0.936. Diantara 12 trait kepercayaan diri terhadap kemampuan komunikasi, mahasiswa yang percaya diri saat berkomunikasi dengan sekelompok orang yang masih asing mempunyai tingkat kecemasan paling rendah (KR suaian=-0.13; DK=-0.21; 0.05; p=0.002. Kesimpulan: Semakin tinggi kepercayaan diri mahasiswa terhadap kemampuan komunikasinya akan semakin rendah tingkat kecemasannya. Untuk itu, fakulta kedokteran perlu memberikan kesempatan bagi mahasiswa mempraktekkan komunikasi public, terutama dengan berbicara kepada sekelompok orang asing. (Health Science Indones 2010; 1: 37 - 42 Kata kunci: berbicara, kelompok, kemampuan komunikasi ABSTRACT Background: A

Inferring topologies via driving-based generalized synchronization of two-layer networks

Science.gov (United States)

Wang, Yingfei; Wu, Xiaoqun; Feng, Hui; Lu, Jun-an; Xu, Yuhua

2016-05-01

The interaction topology among the constituents of a complex network plays a crucial role in the network’s evolutionary mechanisms and functional behaviors. However, some network topologies are usually unknown or uncertain. Meanwhile, coupling delays are ubiquitous in various man-made and natural networks. Hence, it is necessary to gain knowledge of the whole or partial topology of a complex dynamical network by taking into consideration communication delay. In this paper, topology identification of complex dynamical networks is investigated via generalized synchronization of a two-layer network. Particularly, based on the LaSalle-type invariance principle of stochastic differential delay equations, an adaptive control technique is proposed by constructing an auxiliary layer and designing proper control input and updating laws so that the unknown topology can be recovered upon successful generalized synchronization. Numerical simulations are provided to illustrate the effectiveness of the proposed method. The technique provides a certain theoretical basis for topology inference of complex networks. In particular, when the considered network is composed of systems with high-dimension or complicated dynamics, a simpler response layer can be constructed, which is conducive to circuit design. Moreover, it is practical to take into consideration perturbations caused by control input. Finally, the method is applicable to infer topology of a subnetwork embedded within a complex system and locate hidden sources. We hope the results can provide basic insight into further research endeavors on understanding practical and economical topology inference of networks.

Direct Communication Systems

OpenAIRE

Krajačić, Ivan

2016-01-01

Today we use numerous methods of direct communications, for which we use a technical term Unified Communications. It is almost impossible to imagine the business world today without Unified Communications, which are improving productivity and reducing costs. The goal of using Unified Communications is to ensure a consistent user experience at any location and any device. Skype for Business, a Microsoft product, is one of the solutions for Unified Communications and is described in this thesis...

Effect of p-layer properties on nanocrystalline absorber layer and thin film silicon solar cells

International Nuclear Information System (INIS)

Chowdhury, Amartya; Adhikary, Koel; Mukhopadhyay, Sumita; Ray, Swati

2008-01-01

The influence of the p-layer on the crystallinity of the absorber layer and nanocrystalline silicon thin film solar cells has been studied. Boron doped Si : H p-layers of different crystallinities have been prepared under different power pressure conditions using the plasma enhanced chemical vapour deposition method. The crystalline volume fraction of p-layers increases with the increase in deposition power. Optical absorption of the p-layer reduces as the crystalline volume fraction increases. Structural studies at the p/i interface have been done by Raman scattering studies. The crystalline volume fraction of the i-layer increases as that of the p-layer increases, the effect being more prominent near the p/i interface. Grain sizes of the absorber layer decrease from 9.2 to 7.2 nm and the density of crystallites increases as the crystalline volume fraction of the p-layer increases and its grain size decreases. With increasing crystalline volume fraction of the p-layer solar cell efficiency increases

Location-assured, multifactor authentication on smartphones via LTE communication

Science.gov (United States)

Kuseler, Torben; Lami, Ihsan A.; Al-Assam, Hisham

2013-05-01

With the added security provided by LTE, geographical location has become an important factor for authentication to enhance the security of remote client authentication during mCommerce applications using Smartphones. Tight combination of geographical location with classic authentication factors like PINs/Biometrics in a real-time, remote verification scheme over the LTE layer connection assures the authenticator about the client itself (via PIN/biometric) as well as the client's current location, thus defines the important aspects of "who", "when", and "where" of the authentication attempt without eaves dropping or man on the middle attacks. To securely integrate location as an authentication factor into the remote authentication scheme, client's location must be verified independently, i.e. the authenticator should not solely rely on the location determined on and reported by the client's Smartphone. The latest wireless data communication technology for mobile phones (4G LTE, Long-Term Evolution), recently being rolled out in various networks, can be employed to enhance this location-factor requirement of independent location verification. LTE's Control Plane LBS provisions, when integrated with user-based authentication and independent source of localisation factors ensures secure efficient, continuous location tracking of the Smartphone. This feature can be performed during normal operation of the LTE-based communication between client and network operator resulting in the authenticator being able to verify the client's claimed location more securely and accurately. Trials and experiments show that such algorithm implementation is viable for nowadays Smartphone-based banking via LTE communication.

Forum: Communication Activism Pedagogy. Communication Activism Pedagogy and Research: Communication Education Scholarship to Promote Social Justice

Science.gov (United States)

Frey, Lawrence R.; Palmer, David L.

2017-01-01

The recent formation of the National Communication Association's Activism and Social Justice Division puts a spotlight on the extent to which instructional communication and instructional communication research have advanced--or even should advance--the goals of social justice. To examine this issue, two of the leading scholars on this topic,…

Communication that heals: mindful communication practices from palliative care leaders.

Science.gov (United States)

Omilion-Hodges, Leah M; Swords, Nathan M

2016-01-01

Though research has begun to highlight the centrality of communication in palliative care, studies have yet to focus on the use of mindful communication. Mindful communication is associated with increases in patient care and decreases in physician burnout. Through in-depth, semi-structured interviews the authors sought mindful communication practices from palliative care leaders in American Hospital Association Circle of Life® award-wining units. Four key mindful communication practices emerged: Know your audience, ask questions, discard scripts, and recognize your role. The discussion articulates how key mindful communication practices may be used as a stage model, where key practices may be used individually or in concert, by sole practitioners or within interdisciplinary teams and by new and seasoned clinicians. Theoretical contributions and areas for future inquiry are also discussed.

Internet-Based Communication

Science.gov (United States)

Gernsbacher, Morton Ann

2014-01-01

Google the question, "How is the Internet changing the way we communicate?," and you will find no shortage of opinions, or fears, about the Internet altering the way we communicate. Although the Internet is not necessarily making communication briefer (neither is the Internet making communication less formal), the Internet is manifesting…

Exponential Communication Complexity Advantage from Quantum Superposition of the Direction of Communication

Science.gov (United States)

Guérin, Philippe Allard; Feix, Adrien; Araújo, Mateus; Brukner, Časlav

2016-09-01

In communication complexity, a number of distant parties have the task of calculating a distributed function of their inputs, while minimizing the amount of communication between them. It is known that with quantum resources, such as entanglement and quantum channels, one can obtain significant reductions in the communication complexity of some tasks. In this work, we study the role of the quantum superposition of the direction of communication as a resource for communication complexity. We present a tripartite communication task for which such a superposition allows for an exponential saving in communication, compared to one-way quantum (or classical) communication; the advantage also holds when we allow for protocols with bounded error probability.

Cholinergic neuromodulation controls directed temporal communication in neocortex in vitro

Directory of Open Access Journals (Sweden)

Anita K Roopun

2010-03-01

Full Text Available Acetylcholine is the primary neuromodulator involved in cortical arousal in mammals. Cholinergic modulation is involved in conscious awareness, memory formation and attention – processes that involve intercommunication between different cortical regions. Such communication is achieved in part through temporal structuring of neuronal activity by population rhythms, particularly in the beta and gamma frequency ranges (12 – 80 Hz. Here we demonstrate, using in vitro and in silico models, that spectrally identical patterns of beta2 and gamma rhythms are generated in primary sensory areas and polymodal association areas by fundamentally different local circuit mechanisms: Glutamatergic excitation induced beta2 frequency population rhythms only in layer 5 association cortex whereas cholinergic neuromodulation induced this rhythm only in layer 5 primary sensory cortex. This region-specific sensitivity of local circuits to cholinergic modulation allowed for control of the extent of cortical temporal interactions. Furthermore, the contrasting mechanisms underlying these beta2 rhythms produced a high degree of directionality, favouring an influence of association cortex over primary auditory cortex.

Cholinergic Neuromodulation Controls Directed Temporal Communication in Neocortex in Vitro

Science.gov (United States)

Roopun, Anita K.; LeBeau, Fiona E.N.; Rammell, James; Cunningham, Mark O.; Traub, Roger D.; Whittington, Miles A.

2010-01-01

Acetylcholine is the primary neuromodulator involved in cortical arousal in mammals. Cholinergic modulation is involved in conscious awareness, memory formation and attention – processes that involve intercommunication between different cortical regions. Such communication is achieved in part through temporal structuring of neuronal activity by population rhythms, particularly in the beta and gamma frequency ranges (12–80 Hz). Here we demonstrate, using in vitro and in silico models, that spectrally identical patterns of beta2 and gamma rhythms are generated in primary sensory areas and polymodal association areas by fundamentally different local circuit mechanisms: Glutamatergic excitation induced beta2 frequency population rhythms only in layer 5 association cortex whereas cholinergic neuromodulation induced this rhythm only in layer 5 primary sensory cortex. This region-specific sensitivity of local circuits to cholinergic modulation allowed for control of the extent of cortical temporal interactions. Furthermore, the contrasting mechanisms underlying these beta2 rhythms produced a high degree of directionality, favouring an influence of association cortex over primary auditory cortex. PMID:20407636

Layer-by-layer assembly of thin film oxygen barrier

International Nuclear Information System (INIS)

Jang, Woo-Sik; Rawson, Ian; Grunlan, Jaime C.

2008-01-01

Thin films of sodium montmorillonite clay and cationic polyacrylamide were grown on a polyethylene terephthalate film using layer-by-layer assembly. After 30 clay-polymer layers are deposited, with a thickness of 571 nm, the resulting transparent film has an oxygen transmission rate (OTR) below the detection limit of commercial instrumentation ( 2 /day/atm). This low OTR, which is unprecedented for a clay-filled polymer composite, is believed to be due to a brick wall nanostructure comprised of completely exfoliated clay in polymeric mortar. With an optical transparency greater than 90% and potential for microwaveability, this thin composite is a good candidate for foil replacement in food packaging and may also be useful for flexible electronics packaging

A hybrid MAC protocol design for energy-efficient very-high-throughput millimeter wave, wireless sensor communication networks

Science.gov (United States)

Jian, Wei; Estevez, Claudio; Chowdhury, Arshad; Jia, Zhensheng; Wang, Jianxin; Yu, Jianguo; Chang, Gee-Kung

2010-12-01

This paper presents an energy-efficient Medium Access Control (MAC) protocol for very-high-throughput millimeter-wave (mm-wave) wireless sensor communication networks (VHT-MSCNs) based on hybrid multiple access techniques of frequency division multiplexing access (FDMA) and time division multiplexing access (TDMA). An energy-efficient Superframe for wireless sensor communication network employing directional mm-wave wireless access technologies is proposed for systems that require very high throughput, such as high definition video signals, for sensing, processing, transmitting, and actuating functions. Energy consumption modeling for each network element and comparisons among various multi-access technologies in term of power and MAC layer operations are investigated for evaluating the energy-efficient improvement of proposed MAC protocol.

The Oral Communication Competence Dilemma: Are We Communicating Competently about Speech Communication?

Science.gov (United States)

Fleuriet, Cathy A.

1997-01-01

Questions survey results which find oral communication education alive and well in higher education. Argues that those outside the discipline need to be educated about the nature of speech communication education and that a concerted effort must be made by faculty and administrators to reinforce the academic credibility of the discipline. (PA)

Intercultural Communication and Disabilities from a Communication Complex Perspective

Directory of Open Access Journals (Sweden)

Джон Пэрриш-Спраул

2015-12-01

Full Text Available Intercultural communication presents a number of challenges that are less of an issue in same-culture interactions. This is important because travel and technological capability enable more and more immigrants, business people, tourists, etc. to engage in such interactions. One group of people that comprises 10% of the world population, the disabled, is increasingly being mainstreamed within cultures as well as traveling to other countries. Research finds that the disabled are often marginalized and discriminated against within their own country. When the abled enter an intercultural interaction with the disabled the communication challenges are even greater. Communication Complex, a metatheoretical perspective on communication that embraces a constitutive definition of communication combined with a neuroscience understanding of interaction, offers a deeper, yet highly practical explanation of the level of complexity that such an encounter entails. This article offers a brief introduction to this way of understanding intercultural communication, along with the suggestion that future studies and practical guides should take disabilities into account when analyzing or building skills.

The Transient Intermediate Plexiform Layer, a Plexiform Layer-like Structure Temporarily Existing in the Inner Nuclear Layer in Developing Rat Retina.

Science.gov (United States)

Park, Hyung Wook; Kim, Hong-Lim; Park, Yong Soo; Kim, In-Beom

2018-02-01

The retina is a highly specialised part of the brain responsible for visual processing. It is well-laminated; three layers containing five different types of neurons are compartmentalised by two synaptic layers. Among the retinal layers, the inner nuclear layer (INL) is composed of horizontal, bipolar, and amacrine cell types. Bipolar cells form one sublayer in the distal half of the IPL, while amacrine cells form another sublayer in the proximal half, without any border-like structure. Here, we report that a plexiform layer-like structure exists temporarily in the border between the bipolar and amacrine sublayers in the INL in the rat retina during retinal development. This transient intermediate plexiform layer (TIPL) appeared at postnatal day (PD) 7 and then disappeared around PD 12. Most apoptotic cells in the INL were found near the TIPL. These results suggest that the TIPL may contribute to the formation of sublayers and the cell number limit in the INL.

Layer-by-layer modification of thin-film metal-semiconductor multilayers with ultrashort laser pulses

Science.gov (United States)

Romashevskiy, S. A.; Tsygankov, P. A.; Ashitkov, S. I.; Agranat, M. B.

2018-05-01

The surface modifications in a multilayer thin-film structure (50-nm alternating layers of Si and Al) induced by a single Gaussian-shaped femtosecond laser pulse (350 fs, 1028 nm) in the air are investigated by means of atomic-force microscopy (AFM), scanning electron microscopy (SEM), and optical microscopy (OM). Depending on the laser fluence, various modifications of nanometer-scale metal and semiconductor layers, including localized formation of silicon/aluminum nanofoams and layer-by-layer removal, are found. While the nanofoams with cell sizes in the range of tens to hundreds of nanometers are produced only in the two top layers, layer-by-layer removal is observed for the four top layers under single pulse irradiation. The 50-nm films of the multilayer structure are found to be separated at their interfaces, resulting in a selective removal of several top layers (up to 4) in the form of step-like (concentric) craters. The observed phenomenon is associated with a thermo-mechanical ablation mechanism that results in splitting off at film-film interface, where the adhesion force is less than the bulk strength of the used materials, revealing linear dependence of threshold fluences on the film thickness.

Asymmetric Temporal Integration of Layer 4 and Layer 2/3 Inputs in Visual Cortex

OpenAIRE

Hang, Giao B.; Dan, Yang

2010-01-01

Neocortical neurons in vivo receive concurrent synaptic inputs from multiple sources, including feedforward, horizontal, and feedback pathways. Layer 2/3 of the visual cortex receives feedforward input from layer 4 and horizontal input from layer 2/3. Firing of the pyramidal neurons, which carries the output to higher cortical areas, depends critically on the interaction of these pathways. Here we examined synaptic integration of inputs from layer 4 and layer 2/3 in rat visual cortical slices...

Crisis Communication (Handbooks of Communication Science Vol. 23)

DEFF Research Database (Denmark)

Johansen, Winni

Vol. 23 - The Handbook of Communication Science General editors: Peter J. Schultz and Paul Cobley......Vol. 23 - The Handbook of Communication Science General editors: Peter J. Schultz and Paul Cobley...

Scaling of load in communications networks.

Science.gov (United States)

Narayan, Onuttom; Saniee, Iraj

2010-09-01

We show that the load at each node in a preferential attachment network scales as a power of the degree of the node. For a network whose degree distribution is p(k)∼k{-γ} , we show that the load is l(k)∼k{η} with η=γ-1 , implying that the probability distribution for the load is p(l)∼1/l{2} independent of γ . The results are obtained through scaling arguments supported by finite size scaling studies. They contradict earlier claims, but are in agreement with the exact solution for the special case of tree graphs. Results are also presented for real communications networks at the IP layer, using the latest available data. Our analysis of the data shows relatively poor power-law degree distributions as compared to the scaling of the load versus degree. This emphasizes the importance of the load in network analysis.

Measuring Communication in Parallel Communicating Finite Automata

Directory of Open Access Journals (Sweden)

Henning Bordihn

2014-05-01

Full Text Available Systems of deterministic finite automata communicating by sending their states upon request are investigated, when the amount of communication is restricted. The computational power and decidability properties are studied for the case of returning centralized systems, when the number of necessary communications during the computations of the system is bounded by a function depending on the length of the input. It is proved that an infinite hierarchy of language families exists, depending on the number of messages sent during their most economical recognitions. Moreover, several properties are shown to be not semi-decidable for the systems under consideration.

Organizational communication process

Directory of Open Access Journals (Sweden)

Kenan Spaho

2012-12-01

Full Text Available Managers spend majority of their time communicating in several forms: meeting, face-to –face dis- cussion, letters, emails etc. Also more and more employees realize that communication is a very im- portant part of their work because a lot of their work activities are based on teamwork among workers in different functional groups. This is the reason why communication has become more important in companies. The experience shows that there are significant differences in manners of communication and that it appears to be a very important factor which makes some organizations more successful than others. Communication is the most important for managers because research shows that the spent long period in work time in communication.

Data communication equipment

International Nuclear Information System (INIS)

Kim, Hak Seon; Lee, Sang Mok

1998-02-01