Design of a Combined Beacon Receiver and Digital Radiometer for 40 GHz Propagation Measurements at the Madrid Deep Space Communications Complex

Science.gov (United States)

Zemba, Michael; Nessel, James; Morabito, David

2017-01-01

NASA Glenn Research Center (GRC) and the Jet Propulsion Laboratory (JPL) have jointly developed an atmospheric propagation terminal to measure and characterize propagation phenomena at 40 GHz at the Madrid Deep Space Communications Complex (MDSCC) in Robledo de Chavela, Spain. The hybrid Q-band system utilizes a novel design which combines a 40 GHz beacon receiver and digital radiometer into the same RF front-end and observes the 39.402 GHz beacon of the European Space Agencys Alphasat Aldo Paraboni TDP5 experiment. Atmospheric measurements include gaseous absorption, rain fade, and scintillation. The radiometric measurement is calibrated by means of an included noise diode as well as tipping calibration. The goals of these measurements are to assist MDSCC mission operations as the facility increasingly supports Ka-band missions, as well as to contribute to the development and improvement of International Telecommunications Union (ITU) models for prediction of communications systems performance within the Q-band through the Aldo Paraboni Experiment. Herein, we provide an overview of the system design, characterization, and plan of operations which commenced at the MDSCC beginning in March 2017.

In-Space Internet-Based Communications for Space Science Platforms Using Commercial Satellite Networks

Science.gov (United States)

Kerczewski, Robert J.; Bhasin, Kul B.; Fabian, Theodore P.; Griner, James H.; Kachmar, Brian A.; Richard, Alan M.

1999-01-01

The continuing technological advances in satellite communications and global networking have resulted in commercial systems that now can potentially provide capabilities for communications with space-based science platforms. This reduces the need for expensive government owned communications infrastructures to support space science missions while simultaneously making available better service to the end users. An interactive, high data rate Internet type connection through commercial space communications networks would enable authorized researchers anywhere to control space-based experiments in near real time and obtain experimental results immediately. A space based communications network architecture consisting of satellite constellations connecting orbiting space science platforms to ground users can be developed to provide this service. The unresolved technical issues presented by this scenario are the subject of research at NASA's Glenn Research Center in Cleveland, Ohio. Assessment of network architectures, identification of required new or improved technologies, and investigation of data communications protocols are being performed through testbed and satellite experiments and laboratory simulations.

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.

Exploring the morphospace of communication efficiency in complex networks.

Directory of Open Access Journals (Sweden)

Joaquín Goñi

Full Text Available Graph theoretical analysis has played a key role in characterizing global features of the topology of complex networks, describing diverse systems such as protein interactions, food webs, social relations and brain connectivity. How system elements communicate with each other depends not only on the structure of the network, but also on the nature of the system's dynamics which are constrained by the amount of knowledge and resources available for communication processes. Complementing widely used measures that capture efficiency under the assumption that communication preferentially follows shortest paths across the network ("routing", we define analytic measures directed at characterizing network communication when signals flow in a random walk process ("diffusion". The two dimensions of routing and diffusion efficiency define a morphospace for complex networks, with different network topologies characterized by different combinations of efficiency measures and thus occupying different regions of this space. We explore the relation of network topologies and efficiency measures by examining canonical network models, by evolving networks using a multi-objective optimization strategy, and by investigating real-world network data sets. Within the efficiency morphospace, specific aspects of network topology that differentially favor efficient communication for routing and diffusion processes are identified. Charting regions of the morphospace that are occupied by canonical, evolved or real networks allows inferences about the limits of communication efficiency imposed by connectivity and dynamics, as well as the underlying selection pressures that have shaped network topology.

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

Using the Phase Space to Design Complexity

DEFF Research Database (Denmark)

Heinrich, Mary Katherine; Ayres, Phil

2016-01-01

Architecture that is responsive, adaptive, or interactive can contain active architectural elements or robotic sensor-actuator systems. The consideration of architectural robotic elements that utilize distributed control and distributed communication allows for self-organization, emergence...... with materializations left by robot swarms or elements, rather than robots' internal states. We detail a case study examination of design methodology using the formation space concept for assessment and decision-making in the design of active architectural artifacts......., and evolution on site in real-time. The potential complexity of behaviors in such architectural robotic systems requires design methodology able to encompass a range of possible outcomes, rather than a single solution. We present an approach of adopting an aspect of complexity science and applying...

Feasible quantum communication complexity protocol

International Nuclear Information System (INIS)

Galvao, Ernesto F.

2002-01-01

I show that a simple multiparty communication task can be performed more efficiently with quantum communication than with classical communication, even with low detection efficiency η. The task is a communication complexity problem in which distant parties need to compute a function of the distributed inputs, while minimizing the amount of communication between them. A realistic quantum optical setup is suggested that can demonstrate a five-party quantum protocol with higher-than-classical performance, provided η>0.33

Modern structure of marketing communications complex

Directory of Open Access Journals (Sweden)

Hrebenyukova Elena

2015-08-01

Full Text Available The article presents the results of the desk research, in which the current structure of the marketing communications complex was analyzed. According to the results of the content analysis of scientific and educational literature in marketing it was proved that there is a certain structural asymmetry in today's complex of marketing communication: the rejection of impersonal tools and actualization of those which make possible personalized communication with the consumer.

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.

Beaconless Pointing for Deep-Space Optical Communication

Science.gov (United States)

Swank, Aaron J.; Aretskin-Hariton, Eliot; Le, Dzu K.; Sands, Obed S.; Wroblewski, Adam

2016-01-01

Free space optical communication is of interest to NASA as a complement to existing radio frequency communication methods. The potential for an increase in science data return capability over current radio-frequency communications is the primary objective. Deep space optical communication requires laser beam pointing accuracy on the order of a few microradians. The laser beam pointing approach discussed here operates without the aid of a terrestrial uplink beacon. Precision pointing is obtained from an on-board star tracker in combination with inertial rate sensors and an outgoing beam reference vector. The beaconless optical pointing system presented in this work is the current approach for the Integrated Radio and Optical Communication (iROC) project.

Communicating space weather to policymakers and the wider public

Science.gov (United States)

Ferreira, Bárbara

2014-05-01

As a natural hazard, space weather has the potential to affect space- and ground-based technological systems and cause harm to human health. As such, it is important to properly communicate this topic to policymakers and the general public alike, informing them (without being unnecessarily alarmist) about the potential impact of space-weather phenomena and how these can be monitored and mitigated. On the other hand, space weather is related to interesting phenomena on the Sun such as coronal-mass ejections, and incorporates one of the most beautiful displays in the Earth and its nearby space environment: aurora. These exciting and fascinating aspects of space weather should be cultivated when communicating this topic to the wider public, particularly to younger audiences. Researchers have a key role to play in communicating space weather to both policymakers and the wider public. Space scientists should have an active role in informing policy decisions on space-weather monitoring and forecasting, for example. And they can exercise their communication skills by talking about space weather to school children and the public in general. This presentation will focus on ways to communicate space weather to wider audiences, particularly policymakers. It will also address the role researchers can play in this activity to help bridge the gap between the space science community and the public.

Space weather effects on communications

Science.gov (United States)

Lanzerotti, Louis J.

In the 150 years since the advent of the first electrical communication system - the electrical telegraph - the diversity of communications technologies that are embedded within space-affected environments have vastly increased. The increasing sophistication of these communications technologies, and how their installation and operations may relate to the environments in which they are embedded, requires ever more sophisticated understanding of natural physical phenomena. At the same time, the business environment for most present-day communications technologies that are affected by space phenomena is very dynamic. The commercial and national security deployment and use of these technologies do not wait for optimum knowledge of possible environmental effects to be acquired before new technological embodiments are created, implemented, and marketed. Indeed, those companies that might foolishly seek perfectionist understanding of natural effects can be left behind by the marketplace. A well-considered balance is needed between seeking ever deeper understanding of physical phenomena and implementing `engineering' solutions to current crises. The research community must try to understand, and operate in, this dynamic environment.

47 CFR 25.273 - Duties regarding space communications transmissions.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Duties regarding space communications transmissions. 25.273 Section 25.273 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Operations § 25.273 Duties regarding space...

Free-space communication with over 100 spatial modes

CSIR Research Space (South Africa)

Rosales-Guzmán, C

2016-10-01

Full Text Available Congress 2016: Advanced Solid State Lasers (ASSL); Applications of Lasers for Sensing and Free Space Communications (LS&C), 30 October - 3 November 2016, Boston, Massachusetts, United States Free-space communication with over 100 spatial modes...

Complexity, erotica and conflict in the urban public space

Directory of Open Access Journals (Sweden)

Enrique Díaz Álvarez

2011-09-01

Full Text Available This article highlights the importance of the urban public space, as the quintessential scenario of intercultural interaction and communication. From a context of globalisation, and from an ethical-political perspective, the author urges a reconsideration of the complexity, eroticism and conflicts that are characterised by coexistence in the city, as elements that are capable of directing dialogue, co-implication and construction of affinities between individuals who enjoy and champion the fact of being different.

Research on Retro-reflecting Modulation in Space Optical Communication System

Science.gov (United States)

Zhu, Yifeng; Wang, Guannan

2018-01-01

Retro-reflecting modulation space optical communication is a new type of free space optical communication technology. Unlike traditional free space optical communication system, it applys asymmetric optical systems to reduce the size, weight and power consumption of the system and can effectively solve the limits of traditional free space optical communication system application, so it can achieve the information transmission. This paper introduces the composition and working principle of retro-reflecting modulation optical communication system, analyzes the link budget of this system, reviews the types of optical system and optical modulator, summarizes this technology future research direction and application prospects.

Space Shuttle Underside Astronaut Communications Performance Evaluation

Science.gov (United States)

Hwu, Shian U.; Dobbins, Justin A.; Loh, Yin-Chung; Kroll, Quin D.; Sham, Catherine C.

2005-01-01

The Space Shuttle Ultra High Frequency (UHF) communications system is planned to provide Radio Frequency (RF) coverage for astronauts working underside of the Space Shuttle Orbiter (SSO) for thermal tile inspection and repairing. This study is to assess the Space Shuttle UHF communication performance for astronauts in the shadow region without line-of-sight (LOS) to the Space Shuttle and Space Station UHF antennas. To insure the RF coverage performance at anticipated astronaut worksites, the link margin between the UHF antennas and Extravehicular Activity (EVA) Astronauts with significant vehicle structure blockage was analyzed. A series of near-field measurements were performed using the NASA/JSC Anechoic Chamber Antenna test facilities. Computational investigations were also performed using the electromagnetic modeling techniques. The computer simulation tool based on the Geometrical Theory of Diffraction (GTD) was used to compute the signal strengths. The signal strength was obtained by computing the reflected and diffracted fields along the propagation paths between the transmitting and receiving antennas. Based on the results obtained in this study, RF coverage for UHF communication links was determined for the anticipated astronaut worksite in the shadow region underneath the Space Shuttle.

Communications among elements of a space construction ensemble

Science.gov (United States)

Davis, Randal L.; Grasso, Christopher A.

1989-01-01

Space construction projects will require careful coordination between managers, designers, manufacturers, operators, astronauts, and robots with large volumes of information of varying resolution, timeliness, and accuracy flowing between the distributed participants over computer communications networks. Within the CSC Operations Branch, we are researching the requirements and options for such communications. Based on our work to date, we feel that communications standards being developed by the International Standards Organization, the CCITT, and other groups can be applied to space construction. We are currently studying in depth how such standards can be used to communicate with robots and automated construction equipment used in a space project. Specifically, we are looking at how the Manufacturing Automation Protocol (MAP) and the Manufacturing Message Specification (MMS), which tie together computers and machines in automated factories, might be applied to space construction projects. Together with our CSC industrial partner Computer Technology Associates, we are developing a MAP/MMS companion standard for space construction and we will produce software to allow the MAP/MMS protocol to be used in our CSC operations testbed.

Challenges of Integrating NASA's Space Communications Networks

Science.gov (United States)

Reinert, Jessica; Barnes, Patrick

2013-01-01

The transition to new technology, innovative ideas, and resistance to change is something that every industry experiences. Recent examples of this shift are changing to using robots in the assembly line construction of automobiles or the increasing use of robotics for medical procedures. Most often this is done with cost-reduction in mind, though ease of use for the customer is also a driver. All industries experience the push to increase efficiency of their systems; National Aeronautics and Space Administration (NASA) and the commercial space industry are no different. NASA space communication services are provided by three separately designed, developed, maintained, and operated communications networks known as the Deep Space Network (DSN), Near Earth Network (NEN) and Space Network (SN). The Space Communications and Navigation (SCaN) Program is pursuing integration of these networks and has performed a variety of architecture trade studies to determine what integration options would be the most effective in achieving a unified user mission support organization, and increase the use of common operational equipment and processes. The integration of multiple, legacy organizations and existing systems has challenges ranging from technical to cultural. The existing networks are the progeny of the very first communication and tracking capabilities implemented by NASA and the Jet Propulsion Laboratory (JPL) more than 50 years ago and have been customized to the needs of their respective user mission base. The technical challenges to integrating the networks are many, though not impossible to overcome. The three distinct networks provide the same types of services, with customizable data rates, bandwidth, frequencies, and so forth. The differences across the networks have occurred in effort to satisfy their user missions' needs. Each new requirement has made the networks more unique and harder to integrate. The cultural challenges, however, have proven to be a

Challenges of Integrating NASAs Space Communication Networks

Science.gov (United States)

Reinert, Jessica M.; Barnes, Patrick

2013-01-01

The transition to new technology, innovative ideas, and resistance to change is something that every industry experiences. Recent examples of this shift are changing to using robots in the assembly line construction of automobiles or the increasing use of robotics for medical procedures. Most often this is done with cost-reduction in mind, though ease of use for the customer is also a driver. All industries experience the push to increase efficiency of their systems; National Aeronautics and Space Administration (NASA) and the commercial space industry are no different. NASA space communication services are provided by three separately designed, developed, maintained, and operated communications networks known as the Deep Space Network (DSN), Near Earth Network (NEN) and Space Network (SN). The Space Communications and Navigation (SCaN) Program is pursuing integration of these networks and has performed a variety of architecture trade studies to determine what integration options would be the most effective in achieving a unified user mission support organization, and increase the use of common operational equipment and processes. The integration of multiple, legacy organizations and existing systems has challenges ranging from technical to cultural. The existing networks are the progeny of the very first communication and tracking capabilities implemented by NASA and the Jet Propulsion Laboratory (JPL) more than 50 years ago and have been customized to the needs of their respective user mission base. The technical challenges to integrating the networks are many, though not impossible to overcome. The three distinct networks provide the same types of services, with customizable data rates, bandwidth, frequencies, and so forth. The differences across the networks have occurred in effort to satisfy their user missions' needs. Each new requirement has made the networks more unique and harder to integrate. The cultural challenges, however, have proven to be a

Space Shuttle Communications Coverage Analysis for Thermal Tile Inspection

Science.gov (United States)

Kroll, Quin D.; Hwu, Shian U.; Upanavage, Matthew; Boster, John P.; Chavez, Mark A.

2009-01-01

The space shuttle ultra-high frequency Space-to-Space Communication System has to provide adequate communication coverage for astronauts who are performing thermal tile inspection and repair on the underside of the space shuttle orbiter (SSO). Careful planning and quantitative assessment are necessary to ensure successful system operations and mission safety in this work environment. This study assesses communication systems performance for astronauts who are working in the underside, non-line-of-sight shadow region on the space shuttle. All of the space shuttle and International Space Station (ISS) transmitting antennas are blocked by the SSO structure. To ensure communication coverage at planned inspection worksites, the signal strength and link margin between the SSO/ISS antennas and the extravehicular activity astronauts, whose line-of-sight is blocked by vehicle structure, was analyzed. Investigations were performed using rigorous computational electromagnetic modeling techniques. Signal strength was obtained by computing the reflected and diffracted fields along the signal propagation paths between transmitting and receiving antennas. Radio frequency (RF) coverage was determined for thermal tile inspection and repair missions using the results of this computation. Analysis results from this paper are important in formulating the limits on reliable communication range and RF coverage at planned underside inspection and repair worksites.

Downlink Fiber Laser Transmitter for Deep Space Communication, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — NASA's Space Communications and Navigation (SCaN) roadmap, calls for an integrated network approach to communication and navigation needs for robotic and human space...

Acousto-optic pointing and tracking systems for free-space laser communications

Science.gov (United States)

Nikulin, V.; Khandekar, R.; Sofka, J.; Tartakovsky, G.

2005-08-01

Implementation of long-range laser communication systems holds great promise for high-bandwidth applications. They are viewed as a technology that in the nearest future will handle most of the "last mile" communication traffic for the individual subscribers, corporate offices, military, and possibly deep space probes. Indeed, lasers allow for concentration of energy within tightly focused beams and narrow spectral interval, thus offering high throughput, information security, weight and size of components and power requirements that could not be matched by RF systems. However, the advantages of optical communication systems come in the same package with several major challenges. In particular, high data rates should be complemented by high-precision wide-bandwidth position control of a laser beam. In many applications the ability to maintain a link is affected by the complex maneuvers performed by mobile communication platforms, resident vibrations, and atmospheric effects. The search for the most effective and reliable way to shape and steer the laser beam is an on-going effort. This paper is focused on the application of acousto-optic technology as an alternative to electro-mechanical devices. With realization that an acousto-optic Bragg cell is only a component of the entire communication system, which should perform complex tasks of acquisition, pointing, and tracking of the remote terminal, we present an attempt to consider this problem from the "systems" point of view.

CHARACTERISTIC OF THE COMPLEX MARKETING COMMUNICATIONS ELEMENTS

Directory of Open Access Journals (Sweden)

Natalia Kovalenko

2017-07-01

Full Text Available Purpose: The purpose and objectives of the article are detailed characterization of marketing communication’s elements and characteristics of synthetic and communications. Methods: The stages of the campaign and main advantages and disadvantages of advertising have been disclosed and analyzed in the article. The marketing communication and some elements of marketing communications, the issues of formation and development of the theory of marketing communications have been studied. Results: This article describes the elements of marketing communications factors and basic tools of marketing communications: advertising, personal selling, complex sales promotion, publicity and public relation, direct marketing. Discussion: Companies must also transmit information to customers and carefully carry out selection of such information. For this order is a complex system of marketing communications. Often marketing communications identified with the products promotion which leads to a false understanding of the nature and, consequently, to the irrational use potential of marketing communications in market activity.

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

Non-Mechanical Beam Steering in Free-Space Optical Communication Transceivers

Science.gov (United States)

Shortt, Kevin

Free-space optical communications systems are a rapidly growing field as they carry many of the advantages of traditional fibre-based communications systems without the added investment of installing complex infrastructure. Moreover, these systems are finding key niches in mobile platforms in order to take advantage of the increased bandwidth over traditional RF systems. Of course, the inevitable problem of tracking arises when dealing with mobile stations. To compound the problem in the case of communications to low Earth or geosynchronous orbits, FSOC systems typically operate with tightly confined beams over great distances often requiring pointing accuracies on the order of micro-radians or smaller. Mechanisms such as gimbal mounts and fine-steering mirrors are the usual candidates for platform stabilization, however, these clearly have substantial power requirements and inflate the mass of the system. Spatial light modulators (also known as optical phased arrays), on the other hand, offer a suitable alternative for beam-pointing stabilization. Some of the advantages of spatial light modulators over fine-steering mirrors include programmable multiple simultaneous beams, dynamic focus/defocus and moderate to excellent optical power handling capability. This thesis serves as an investigation into the implementation of spatial light modulators as a replacement for traditional fine-steering mirrors in the fine-pointing subsystem. In particular, pointing accuracy and scanning ability will be highlighted as performance metrics in the context of a variety of communication scenarios. Keywords: Free-space optical communications, beam steering, fine-steering mirror, spatial light modulator, optical phased array.

The museum foyer as a transformative space of communication

DEFF Research Database (Denmark)

Laursen, Ditte; Kristiansen, Erik; Drotner, Kirsten

2016-01-01

has four transformative functions, and we ask the following question: How do people entering the museum practise these transformative functions so as to become visitors – and become non-visitors again on leaving? Answers are provided through an empirical analysis of the foyer as a transformative...... communicative space. Based on qualitative studies of four divergent Danish museums and a science centre, we demonstrate that the foyer’s communicative space supports transformative functions consisting of multiple phases before and after the visit itself, namely arrival–orientation–service–preparation (before......This article explores how we may study physical museum foyers as multilayered spaces of communication. Based on a critical examination of ways in which the museum foyer is conceptualised in the research literature, we define the foyer as a transformative space of communication for visitors which...

Enabling Future Science and Human Exploration with NASA's Next Generation Near Earth and Deep Space Communications and Navigation Architecture

Science.gov (United States)

Reinhart, Richard; Schier, James; Israel, David; Tai, Wallace; Liebrecht, Philip; Townes, Stephen

2017-01-01

The National Aeronautics and Space Administration (NASA) is studying alternatives for the United States space communications architecture through the 2040 timeframe. This architecture provides communication and navigation services to both human exploration and science missions throughout the solar system. Several of NASA's key space assets are approaching their end of design life and major systems are in need of replacement. The changes envisioned in the relay satellite architecture and capabilities around both Earth and Mars are significant undertakings and occur only once or twice each generation, and therefore is referred to as NASA's next generation space communications architecture. NASA's next generation architecture will benefit from technology and services developed over recent years. These innovations will provide missions with new operations concepts, increased performance, and new business and operating models. Advancements in optical communications will enable high-speed data channels and the use of new and more complex science instruments. Modern multiple beam/multiple access technologies such as those employed on commercial high throughput satellites will enable enhanced capabilities for on-demand service, and with new protocols will help provide Internet-like connectivity for cooperative spacecraft to improve data return and coordinate joint mission objectives. On-board processing with autonomous and cognitive networking will play larger roles to help manage system complexity. Spacecraft and ground systems will coordinate among themselves to establish communications, negotiate link connectivity, and learn to share spectrum to optimize resource allocation. Spacecraft will autonomously navigate, plan trajectories, and handle off-nominal events. NASA intends to leverage the ever-expanding capabilities of the satellite communications industry and foster its continued growth. NASA's technology development will complement and extend commercial capabilities

Enabling Future Science and Human Exploration with NASA's Next Generation near Earth and Deep Space Communications and Navigation Architecture

Science.gov (United States)

Reinhart, Richard C.; Schier, James S.; Israel, David J.; Tai, Wallace; Liebrecht, Philip E.; Townes, Stephen A.

2017-01-01

The National Aeronautics and Space Administration (NASA) is studying alternatives for the United States space communications architecture through the 2040 timeframe. This architecture provides communication and navigation services to both human exploration and science missions throughout the solar system. Several of NASA's key space assets are approaching their end of design life and major systems are in need of replacement. The changes envisioned in the relay satellite architecture and capabilities around both Earth and Mars are significant undertakings and occur only once or twice each generation, and therefore is referred to as NASA's next generation space communications architecture. NASA's next generation architecture will benefit from technology and services developed over recent years. These innovations will provide missions with new operations concepts, increased performance, and new business and operating models. Advancements in optical communications will enable high-speed data channels and the use of new and more complex science instruments. Modern multiple beam/multiple access technologies such as those employed on commercial high throughput satellites will enable enhanced capabilities for on-demand service, and with new protocols will help provide Internet-like connectivity for cooperative spacecraft to improve data return and coordinate joint mission objectives. On-board processing with autonomous and cognitive networking will play larger roles to help manage system complexity. Spacecraft and ground systems will coordinate among themselves to establish communications, negotiate link connectivity, and learn to share spectrum to optimize resource allocation. Spacecraft will autonomously navigate, plan trajectories, and handle off-nominal events. NASA intends to leverage the ever-expanding capabilities of the satellite communications industry and foster its continued growth. NASA's technology development will complement and extend commercial capabilities

Free-space communication based on quantum cascade laser

International Nuclear Information System (INIS)

Liu Chuanwei; Zhai Shenqiang; Zhang Jinchuan; Zhou Yuhong; Jia Zhiwei; Liu Fengqi; Wang Zhanguo

2015-01-01

A free-space communication based on a mid-infrared quantum cascade laser (QCL) is presented. A room-temperature continuous-wave distributed-feedback (DFB) QCL combined with a mid-infrared detector comprise the basic unit of the communication system. Sinusoidal signals at a highest frequency of 40 MHz and modulated video signals with a carrier frequency of 30 MHz were successfully transmitted with this experimental setup. Our research has provided a proof-of-concept demonstration of space optical communication application with QCL. The highest operation frequency of our setup was determined by the circuit-limited modulation bandwidth. A high performance communication system can be obtained with improved modulation circuit system. (paper)

Teaching Paraeducators to Support the Communication of Young Children with Complex Communication Needs

Science.gov (United States)

Douglas, Sarah N.; Light, Janice C.; McNaughton, David B.

2013-01-01

Paraeducators are frequent communication partners for young children with complex communication needs (CCN) in early childhood settings. This study examined the impact of instruction to paraeducators in two communication interaction strategies (IPLAN [Identify activities for communication, Provide means for communication, Locate and provide…

The physics of communicability in complex networks

International Nuclear Information System (INIS)

Estrada, Ernesto; Hatano, Naomichi; Benzi, Michele

2012-01-01

A fundamental problem in the study of complex networks is to provide quantitative measures of correlation and information flow between different parts of a system. To this end, several notions of communicability have been introduced and applied to a wide variety of real-world networks in recent years. Several such communicability functions are reviewed in this paper. It is emphasized that communication and correlation in networks can take place through many more routes than the shortest paths, a fact that may not have been sufficiently appreciated in previously proposed correlation measures. In contrast to these, the communicability measures reviewed in this paper are defined by taking into account all possible routes between two nodes, assigning smaller weights to longer ones. This point of view naturally leads to the definition of communicability in terms of matrix functions, such as the exponential, resolvent, and hyperbolic functions, in which the matrix argument is either the adjacency matrix or the graph Laplacian associated with the network. Considerable insight on communicability can be gained by modeling a network as a system of oscillators and deriving physical interpretations, both classical and quantum-mechanical, of various communicability functions. Applications of communicability measures to the analysis of complex systems are illustrated on a variety of biological, physical and social networks. The last part of the paper is devoted to a review of the notion of locality in complex networks and to computational aspects that by exploiting sparsity can greatly reduce the computational efforts for the calculation of communicability functions for large networks.

Communication Analysis of Information Complexes.

Science.gov (United States)

Malik, M. F.

Communication analysis is a tool for perceptual assessment of existing or projected information complexes, i.e., an established reality perceived by one or many humans. An information complex could be of a physical nature, such as a building, landscape, city street; or of a pure informational nature, such as a film, television program,…

Software Defined Radio Architecture Contributions to Next Generation Space Communications

Science.gov (United States)

Kacpura, Thomas J.; Eddy, Wesley M.; Smith, Carl R.; Liebetreu, John

2015-01-01

Space communications architecture concepts, comprising the elements of the system, the interactions among them, and the principles that govern their development, are essential factors in developing National Aeronautics and Space Administration (NASA) future exploration and science missions. Accordingly, vital architectural attributes encompass flexibility, the extensibility to insert future capabilities, and to enable evolution to provide interoperability with other current and future systems. Space communications architectures and technologies for this century must satisfy a growing set of requirements, including those for Earth sensing, collaborative observation missions, robotic scientific missions, human missions for exploration of the Moon and Mars where surface activities require supporting communications, and in-space observatories for observing the earth, as well as other star systems and the universe. An advanced, integrated, communications infrastructure will enable the reliable, multipoint, high-data-rate capabilities needed on demand to provide continuous, maximum coverage for areas of concentrated activity. Importantly, the cost/value proposition of the future architecture must be an integral part of its design; an affordable and sustainable architecture is indispensable within anticipated future budget environments. Effective architecture design informs decision makers with insight into the capabilities needed to efficiently satisfy the demanding space-communication requirements of future missions and formulate appropriate requirements. A driving requirement for the architecture is the extensibility to address new requirements and provide low-cost on-ramps for new capabilities insertion, ensuring graceful growth as new functionality and new technologies are infused into the network infrastructure. In addition to extensibility, another key architectural attribute of the space communication equipment's interoperability with other NASA communications

FUEL HANDLING FACILITY BACKUP CENTRAL COMMUNICATIONS ROOM SPACE REQUIREMENTS CALCULATION

International Nuclear Information System (INIS)

SZALEWSKI, B.

2005-01-01

The purpose of the Fuel Handling Facility Backup Central Communications Room Space Requirements Calculation is to determine a preliminary estimate of the space required to house the backup central communications room in the Fuel Handling Facility (FHF). This room provides backup communications capability to the primary communication systems located in the Central Control Center Facility. This calculation will help guide FHF designers in allocating adequate space for communications system equipment in the FHF. This is a preliminary calculation determining preliminary estimates based on the assumptions listed in Section 4. As such, there are currently no limitations on the use of this preliminary calculation. The calculations contained in this document were developed by Design and Engineering and are intended solely for the use of Design and Engineering in its work regarding the FHF Backup Central Communications Room Space Requirements. Yucca Mountain Project personnel from Design and Engineering should be consulted before the use of the calculations for purposes other than those stated herein or use by individuals other than authorized personnel in Design and Engineering

Overview of some projects of SNPS for global space communication

International Nuclear Information System (INIS)

Ivanov, E.; Ghitaykin, V.; Ionkin, V.; Dubinin, A.; Pyshko, A.

2001-01-01

In this presentation we focused on three variants of prospective concepts of SNPS. They are intended to solve tasks of global space communication (GSC) as nearest future tasks in space. Modern concepts of the application of power technology in space believe in using an onboard source of energy for maintenance of self-transportation of the vehicle into geostationary orbit (GSO). There are three more prospective systems as follows: gas cooled nuclear reactor with hybrid thermal engine and machine power converter; nuclear reactor cooled by liquid metal and with a thermoelectric power generating system; nuclear reactor with Li cooling and a thermionic and thermoelectric power generator on board. The choice of a concept must fit strong requirements such as: space nuclear power unit is aimed to be used in a powerful mission; space power unit must be able to maintain the dual - mode regime of vehicle operation (self - transportation and long life in geosynchronous orbit [GEO]); nuclear rector of unit must be safety and it must be designed in such a way that it will ensure minimum size of the complete system; the elements of the considered technology can be used for the creation of NPPI and with other sources of heat (for example, radioisotope); the degree of technical and technological readiness of units of the thermal and power circuit of installation is estimated to be high and is defined by a number of technological developments in air, space and nuclear branches; nuclear reactor and heat transfer equipment should work in a normal mode, which can be very reliably confirmed for other high-temperature nuclear systems. Considering these concepts we practically consider one of possible strategy of developing of complex system of nuclear power engineering. It is the strategy of step-by-step development of space engineering with real application of them in commercial, scientific and other powerful missions in the nearest and deep space. As starting point of this activity is

Communication Partners Supporting Children with Complex Communication Needs Who Use AAC: A Systematic Review

Science.gov (United States)

Shire, Stephanie Y.; Jones, Nancy

2015-01-01

Communication partners who efficiently use augmentative and alternative communication (AAC) are essential interaction partners for children learning to communicate using AAC. This systematic review examines studies targeting interventions designed to help communication partners support children with complex communication needs who use AAC.…

Digital communication constraints in prior space missions

Science.gov (United States)

Yassine, Nathan K.

2004-01-01

Digital communication is crucial for space endeavors. Jt transmits scientific and command data between earth stations and the spacecraft crew. It facilitates communications between astronauts, and provides live coverage during all phases of the mission. Digital communications provide ground stations and spacecraft crew precise data on the spacecraft position throughout the entire mission. Lessons learned from prior space missions are valuable for our new lunar and Mars missions set by our president s speech. These data will save our agency time and money, and set course our current developing technologies. Limitations on digital communications equipment pertaining mass, volume, data rate, frequency, antenna type and size, modulation, format, and power in the passed space missions are of particular interest. This activity is in support of ongoing communication architectural studies pertaining to robotic and human lunar exploration. The design capabilities and functionalities will depend on the space and power allocated for digital communication equipment. My contribution will be gathering these data, write a report, and present it to Communications Technology Division Staff. Antenna design is very carefully studied for each mission scenario. Currently, Phased array antennas are being developed for the lunar mission. Phased array antennas use little power, and electronically steer a beam instead of DC motors. There are 615 patches in the phased array antenna. These patches have to be modified to have high yield. 50 patches were created for testing. My part is to assist in the characterization of these patch antennas, and determine whether or not certain modifications to quartz micro-strip patch radiators result in a significant yield to warrant proceeding with repairs to the prototype 19 GHz ferroelectric reflect-array antenna. This work requires learning how to calibrate an automatic network, and mounting and testing antennas in coaxial fixtures. The purpose of this

Communication complexity reduction from globally uncorrelated states

International Nuclear Information System (INIS)

Wieśniak, Marcin

2015-01-01

Bell inequality violating entangled states are the working horse for many potential quantum information processing applications, including secret sharing, cryptographic key distribution and communication complexity reduction in distributed computing. Here we explicitly demonstrate the power of certain multi-qubit states to improve the efficiency of partners in joint computation of some multi-qubit function, despite the fact that there could be no correlations between all distributed particles. It is important to stress that the class of functions that can be computed more efficiently is widened, as compared with the standard Bell inequalities. - Highlights: • We expand the set of functions, which can be computed more efficiently with quantum states. • We describe communication complexity reduction protocols based not only on full correlations. • We explicitly show an instance where, a globally uncorrelated state reduces communication complexity

Communication complexity reduction from globally uncorrelated states

Energy Technology Data Exchange (ETDEWEB)

Wieśniak, Marcin, E-mail: marcin.wiesniak@univie.ac.at

2015-04-03

Bell inequality violating entangled states are the working horse for many potential quantum information processing applications, including secret sharing, cryptographic key distribution and communication complexity reduction in distributed computing. Here we explicitly demonstrate the power of certain multi-qubit states to improve the efficiency of partners in joint computation of some multi-qubit function, despite the fact that there could be no correlations between all distributed particles. It is important to stress that the class of functions that can be computed more efficiently is widened, as compared with the standard Bell inequalities. - Highlights: • We expand the set of functions, which can be computed more efficiently with quantum states. • We describe communication complexity reduction protocols based not only on full correlations. • We explicitly show an instance where, a globally uncorrelated state reduces communication complexity.

SPACE COMMUNICATION AND THE MASS MEDIA. A UNESCO REPORT ON THE OCCASION OF THE 1963 SPACE COMMUNICATIONS CONFERENCE. REPORTS AND PAPERS ON MASS COMMUNICATION.

Science.gov (United States)

United Nations Educational, Scientific, and Cultural Organization, Paris (France).

THIS REPORT DEFINES AND ANALYZES POTENTIAL ASPECTS OF WORLDWIDE COMMUNICATION BY SATELLITE, LISTS TECHNICAL PROBLEMS, AND SUGGESTS USES OF SPACE COMMUNICATION TO PROMOTE EDUCATION, CULTURAL EXCHANGE, AND INFORMATION FLOW. IT IS AVAILABLE FOR $0.50 FROM NATIONAL DISTRIBUTORS OF UNESCO PUBLICATIONS, OR FROM UNESCO, PLACE DE FONTENDOY, PARIS-7E,…

Research in space commercialization, technology transfer and communications, vol. 2

Science.gov (United States)

Dunn, D. A.; Agnew, C. E.

1983-01-01

Spectrum management, models for evaluating communications systems, and implications of communications regulations for NASA are considered as major parts of communications policy. Marketing LANDSAT products in developing countries, a political systems analysis of LANDSAT, and private financing and operation of the space operations center (space station) are discussed. Investment requirements, risks, government support, and other primary business and management considerations are examined.

Deep-space and near-Earth optical communications by coded orbital angular momentum (OAM) modulation.

Science.gov (United States)

Djordjevic, Ivan B

2011-07-18

In order to achieve multi-gigabit transmission (projected for 2020) for the use in interplanetary communications, the usage of large number of time slots in pulse-position modulation (PPM), typically used in deep-space applications, is needed, which imposes stringent requirements on system design and implementation. As an alternative satisfying high-bandwidth demands of future interplanetary communications, while keeping the system cost and power consumption reasonably low, in this paper, we describe the use of orbital angular momentum (OAM) as an additional degree of freedom. The OAM is associated with azimuthal phase of the complex electric field. Because OAM eigenstates are orthogonal the can be used as basis functions for N-dimensional signaling. The OAM modulation and multiplexing can, therefore, be used, in combination with other degrees of freedom, to solve the high-bandwidth requirements of future deep-space and near-Earth optical communications. The main challenge for OAM deep-space communication represents the link between a spacecraft probe and the Earth station because in the presence of atmospheric turbulence the orthogonality between OAM states is no longer preserved. We will show that in combination with LDPC codes, the OAM-based modulation schemes can operate even under strong atmospheric turbulence regime. In addition, the spectral efficiency of proposed scheme is N2/log2N times better than that of PPM.

Exotic Optical Beam Classes for Free-Space Communication

Science.gov (United States)

2016-03-24

wandering of an optical vortex is one of the significant problems with the application of vortex beams to FSO applications. From a geometrical optics ...AFRL-AFOSR-VA-TR-2016-0131 Exotic optical beam classes for free-space communication Greg Gbur UNIVERSITY OF NOTH CAROLINA AT CHARLOTTE Final Report...12-2015 4. TITLE AND SUBTITLE Exotic optical beam classes for free-space communication 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1-0009 5c

Reinforcing Visual Grouping Cues to Communicate Complex Informational Structure.

Science.gov (United States)

Bae, Juhee; Watson, Benjamin

2014-12-01

In his book Multimedia Learning [7], Richard Mayer asserts that viewers learn best from imagery that provides them with cues to help them organize new information into the correct knowledge structures. Designers have long been exploiting the Gestalt laws of visual grouping to deliver viewers those cues using visual hierarchy, often communicating structures much more complex than the simple organizations studied in psychological research. Unfortunately, designers are largely practical in their work, and have not paused to build a complex theory of structural communication. If we are to build a tool to help novices create effective and well structured visuals, we need a better understanding of how to create them. Our work takes a first step toward addressing this lack, studying how five of the many grouping cues (proximity, color similarity, common region, connectivity, and alignment) can be effectively combined to communicate structured text and imagery from real world examples. To measure the effectiveness of this structural communication, we applied a digital version of card sorting, a method widely used in anthropology and cognitive science to extract cognitive structures. We then used tree edit distance to measure the difference between perceived and communicated structures. Our most significant findings are: 1) with careful design, complex structure can be communicated clearly; 2) communicating complex structure is best done with multiple reinforcing grouping cues; 3) common region (use of containers such as boxes) is particularly effective at communicating structure; and 4) alignment is a weak structural communicator.

Atmospheric free-space coherent optical communications with adaptive optics

Science.gov (United States)

Ting, Chueh; Zhang, Chengyu; Yang, Zikai

2017-02-01

Free-space coherent optical communications have a potential application to offer last mile bottleneck solution in future local area networks (LAN) because of their information carrier, information security and license-free status. Coherent optical communication systems using orthogonal frequency division multiplexing (OFDM) digital modulation are successfully demonstrated in a long-haul tens Giga bits via optical fiber, but they are not yet available in free space due to atmospheric turbulence-induced channel fading. Adaptive optics is recognized as a promising technology to mitigate the effects of atmospheric turbulence in free-space optics. In this paper, a free-space coherent optical communication system using an OFDM digital modulation scheme and adaptive optics (FSO OFDM AO) is proposed, a Gamma-Gamma distribution statistical channel fading model for the FSO OFDM AO system is examined, and FSO OFDM AO system performance is evaluated in terms of bit error rate (BER) versus various propagation distances.

Diamond Electron-Spin Clocks For Space Navigation and Communication

Data.gov (United States)

National Aeronautics and Space Administration — Precision clocks are needed in a broad range of applications, including satellite communication, high-bandwidth wireless communication, computing systems, and...

Research progress of free space coherent optical communication

Science.gov (United States)

Tan, Zhenkun; Ke, Xizheng

2018-02-01

This paper mainly introduces the research progress of free space coherent optical communication in Xi'an University of Technology. In recent years, the research on the outer modulation technology of the laser, free-space-to-fiber coupling technique, the design of transmitting and receiving optical antenna, adaptive optical technology with or without wave-front sensor, automatic polarization control technology, frequency stabilization technology, heterodyne detection technology and high speed signal processing technology. Based on the above related research, the digital signal modulation, transmission, detection and data recovery are realized by the heterodyne detection technology in the free space optical communication system, and finally the function of smooth viewing high-definition video is realized.

Promoting Conditional Use of Communication Skills for Learners With Complex Communication Needs: A Tutorial.

Science.gov (United States)

Simacek, Jessica; Reichle, Joe; Byiers, Breanne J; Parker-McGowan, Quannah; Dimian, Adele F; Elmquist, Marianne

2018-05-03

Conditional use of communication skills refers to the ability of a learner to appropriately generalize and discriminate when, where, and how to communicate based on constant variation and shifts in environmental cues. We describe discrimination and generalization challenges encountered by learners with complex communication needs and ways in which these challenges are fostered through traditional communication intervention programming. We address arrangements in instruction that maximize the probability of learners acquiring the conditional use of new vocabulary and the modest instructional technology implemented when planning for generalization. We propose establishing well-discriminated and generalized use of new vocabulary items through the application of a general case instruction framework to communication intervention programming. We provide intervention methodology, including intervention steps for general case instruction, a plethora of functional examples, and graphic displays to assess and intervene to promote conditional use of communication skills for learners with complex communication needs.

Facility for the evaluation of space communications and related systems

Science.gov (United States)

Kerczewski, Robert J.; Svoboda, James S.; Kachmar, Brian A.

1995-01-01

NASA Lewis Research Center's Communications Projects Branch has developed a facility for the evaluation of space communications systems and related types of systems, called the Advanced Space Communications (ASC) Laboratory. The ASC Lab includes instrumentation, testbed hardware, and experiment control and monitor software for the evaluation of components, subsystems, systems, and networks. The ASC lab has capabilities to perform radiofrequency (RF), microwave, and millimeter-wave characterizations as well as measurements using low, medium, or high data rate digital signals. In addition to laboratory measurements, the ASC Lab also includes integrated satellite ground terminals allowing experimentation and measurements accessing operational satellites through real space links.

Laser guide stars for optical free-space communications

Science.gov (United States)

Mata-Calvo, Ramon; Bonaccini Calia, Domenico; Barrios, Ricardo; Centrone, Mauro; Giggenbach, Dirk; Lombardi, Gianluca; Becker, Peter; Zayer, Igor

2017-02-01

The German Aerospace Center (DLR) and the European Southern Observatory (ESO) performed a measurement campaign together in April and July 2016 at Teide-Observatory (Tenerife), with the support of the European Space Agency (ESA), to investigate the use of laser guide stars (LGS) in ground to space optical communications. Atmospheric turbulence causes strong signal fluctuations in the uplink, due to scintillation and beam wander. In space communications, the use of the downlink channel as reference for pointing and for pre-distortion adaptive optics is limited by the size of the isokinetic and isoplanatic angle in relation to the required point-ahead angle. Pointing and phase errors due to the decorrelation between downward and upward beam due to the point-ahead angle may have a severe impact on the required transmit power and the stability of the communications link. LGSs provide a self-tailored reference to any optical ground-to-space link, independently of turbulence conditions and required point-ahead angle. In photon-starved links, typically in deep-space scenarios, LGSs allow dedicating all downlink received signal to communications purposes, increasing the available link margin. The scope of the joint DLR-ESO measurement campaign was, first, to measure the absolute value of the beam wander (uplink-tilt) using a LGS, taking a natural star as a reference, and, second, to characterize the decrease of correlation between uplink-tilt and downlink-tilt with respect to the angular separation between both sources. This paper describes the experiments performed during the measurement campaigns, providing an overview of the measured data and the first outcomes of the data post-processing.

Radio-wave propagation for space communications systems

Science.gov (United States)

Ippolito, L. J.

1981-01-01

The most recent information on the effects of Earth's atmosphere on space communications systems is reviewed. The design and reliable operation of satellite systems that provide the many applications in space which rely on the transmission of radio waves for communications and scientific purposes are dependent on the propagation characteristics of the transmission path. The presence of atmospheric gases, clouds, fog, precipitation, and turbulence causes uncontrolled variations in the signal characteristics. These variations can result in a reduction of the quality and reliability of the transmitted information. Models and other techniques are used in the prediction of atmospheric effects as influenced by frequency, geography, elevation angle, and type of transmission. Recent data on performance characteristics obtained from direct measurements on satellite links operating to above 30 GHz have been reviewed. Particular emphasis has been placed on the effects of precipitation on the Earth/space path, including rain attenuation, and ice particle depolarization. Other factors are sky noise, antenna gain degradation, scintillations, and bandwidth coherence. Each of the various propagation factors has an effect on design criteria for communications systems. These criteria include link reliability, power margins, noise contribution, modulation and polarization factors, channel cross talk, error rate, and bandwidth limitations.

The real meaning of complex Minkowski-space world-lines

Energy Technology Data Exchange (ETDEWEB)

Adamo, T M [University of Oxford, Mathematical Institute, 24-29 St Giles, Oxford, OX1 3LB (United Kingdom); Newman, E T, E-mail: newman@pitt.ed [University of Pittsburgh, Department of Physics and Astronomy, Pittsburgh, PA 15213 (United States)

2010-04-07

In connection with the study of shear-free null geodesics in Minkowski space, we investigate the real geometric effects in real Minkowski space that are induced by and associated with complex world-lines in complex Minkowski space. It was already known, in a formal manner, that complex analytic curves in complex Minkowski space induce shear-free null geodesic congruences. Here we look at the direct geometric connections of the complex line and the real structures. Among other items, we show, in particular, how a complex world-line projects into the real Minkowski space in the form of a real shear-free null geodesic congruence.

The real meaning of complex Minkowski-space world-lines

International Nuclear Information System (INIS)

Adamo, T M; Newman, E T

2010-01-01

In connection with the study of shear-free null geodesics in Minkowski space, we investigate the real geometric effects in real Minkowski space that are induced by and associated with complex world-lines in complex Minkowski space. It was already known, in a formal manner, that complex analytic curves in complex Minkowski space induce shear-free null geodesic congruences. Here we look at the direct geometric connections of the complex line and the real structures. Among other items, we show, in particular, how a complex world-line projects into the real Minkowski space in the form of a real shear-free null geodesic congruence.

Development of the Free-space Optical Communications Analysis Software (FOCAS)

Science.gov (United States)

Jeganathan, M.; Mecherle, G.; Lesh, J.

1998-01-01

The Free-space Optical Communications Analysis Software (FOCAS) was developed at the Jet Propulsion Laboratory (JPL) to provide mission planners, systems engineers and communications engineers with an easy to use tool to analyze optical communications link.

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.

Project communication management in complex environments

CERN Document Server

Ying, Zhong

2014-01-01

This unique book that deals with project communication management in complex environments, taking a leaf from China’s experience with a major earthquake in Sichuan, would be a timely contribution to fill this lacuna. Readers would be able to understand how companies and organizations that are unprepared for crisis management would react to their detriment. The lessons provided in this book are the only one of its kind to highlight the lessons for companies and organizations to prepare themselves for successful project communication management through the complexity-informed framework. Although the book is written by two building professionals, the concepts and lessons presented are generic and equally applicable for businesses outside of the construction industry; for example, for airports, resorts, hotels, shipyards, etc.

Trace spaces in a pre-cubical complex

DEFF Research Database (Denmark)

Raussen, Martin

2009-01-01

In directed algebraic topology, directed irreversible (d)-paths and spaces consisting of d-paths are studied from a topological and from a categorical point of view. Motivated by models for concurrent computation, we study in this paper spaces of d-paths in a pre-cubical complex. Such paths...... are equipped with a natural arc length which moreover is shown to be invariant under directed homotopies. D-paths up to reparametrization (called traces) can thus be represented by arc length parametrized d-paths. Under weak additional conditions, it is shown that trace spaces in a pre-cubical complex...... are separable metric spaces which are locally contractible and locally compact. Moreover, they have the homotopy type of a CW-complex....

Research into command, control, and communications in space construction

Science.gov (United States)

Davis, Randal

1990-01-01

Coordinating and controlling large numbers of autonomous or semi-autonomous robot elements in a space construction activity will present problems that are very different from most command and control problems encountered in the space business. As part of our research into the feasibility of robot constructors in space, the CSC Operations Group is examining a variety of command, control, and communications (C3) issues. Two major questions being asked are: can we apply C3 techniques and technologies already developed for use in space; and are there suitable terrestrial solutions for extraterrestrial C3 problems? An overview of the control architectures, command strategies, and communications technologies that we are examining is provided and plans for simulations and demonstrations of our concepts are described.

A Mobile Communications Space Link Between the Space Shuttle Orbiter and the Advanced Communications Technology Satellite

Science.gov (United States)

Fink, Patrick; Arndt, G. D.; Bondyopadhyay, P.; Shaw, Roland

1994-01-01

A communications experiment is described as a link between the Space Shuttle Orbiter (SSO) and the Advanced Communications Technology Satellite (ACTS). Breadboarding for this experiment has led to two items with potential for commercial application: a 1-Watt Ka-band amplifier and a Ka-band, circularly polarized microstrip antenna. Results of the hybrid Ka-band amplifier show gain at 30 dB and a saturated output power of 28.5 dBm. A second version comprised of MMIC amplifiers is discussed. Test results of the microstrip antenna subarray show a gain of approximately 13 dB and excellent circular polarization.

An Optimizing Space Data-Communications Scheduling Method and Algorithm with Interference Mitigation, Generalized for a Broad Class of Optimization Problems

Science.gov (United States)

Rash, James

2014-01-01

NASA's space data-communications infrastructure-the Space Network and the Ground Network-provide scheduled (as well as some limited types of unscheduled) data-communications services to user spacecraft. The Space Network operates several orbiting geostationary platforms (the Tracking and Data Relay Satellite System (TDRSS)), each with its own servicedelivery antennas onboard. The Ground Network operates service-delivery antennas at ground stations located around the world. Together, these networks enable data transfer between user spacecraft and their mission control centers on Earth. Scheduling data-communications events for spacecraft that use the NASA communications infrastructure-the relay satellites and the ground stations-can be accomplished today with software having an operational heritage dating from the 1980s or earlier. An implementation of the scheduling methods and algorithms disclosed and formally specified herein will produce globally optimized schedules with not only optimized service delivery by the space data-communications infrastructure but also optimized satisfaction of all user requirements and prescribed constraints, including radio frequency interference (RFI) constraints. Evolutionary algorithms, a class of probabilistic strategies for searching large solution spaces, is the essential technology invoked and exploited in this disclosure. Also disclosed are secondary methods and algorithms for optimizing the execution efficiency of the schedule-generation algorithms themselves. The scheduling methods and algorithms as presented are adaptable to accommodate the complexity of scheduling the civilian and/or military data-communications infrastructure within the expected range of future users and space- or ground-based service-delivery assets. Finally, the problem itself, and the methods and algorithms, are generalized and specified formally. The generalized methods and algorithms are applicable to a very broad class of combinatorial

Quantum communication complexity advantage implies violation of a Bell inequality

Science.gov (United States)

Buhrman, Harry; Czekaj, Łukasz; Grudka, Andrzej; Horodecki, Michał; Horodecki, Paweł; Markiewicz, Marcin; Speelman, Florian; Strelchuk, Sergii

2016-01-01

We obtain a general connection between a large quantum advantage in communication complexity and Bell nonlocality. We show that given any protocol offering a sufficiently large quantum advantage in communication complexity, there exists a way of obtaining measurement statistics that violate some Bell inequality. Our main tool is port-based teleportation. If the gap between quantum and classical communication complexity can grow arbitrarily large, the ratio of the quantum value to the classical value of the Bell quantity becomes unbounded with the increase in the number of inputs and outputs. PMID:26957600

Security Policy for a Generic Space Exploration Communication Network Architecture

Science.gov (United States)

Ivancic, William D.; Sheehe, Charles J.; Vaden, Karl R.

2016-01-01

This document is one of three. It describes various security mechanisms and a security policy profile for a generic space-based communication architecture. Two other documents accompany this document- an Operations Concept (OpsCon) and a communication architecture document. The OpsCon should be read first followed by the security policy profile described by this document and then the architecture document. The overall goal is to design a generic space exploration communication network architecture that is affordable, deployable, maintainable, securable, evolvable, reliable, and adaptable. The architecture should also require limited reconfiguration throughout system development and deployment. System deployment includes subsystem development in a factory setting, system integration in a laboratory setting, launch preparation, launch, and deployment and operation in space.

Correlation/Communication complexity of generating bipartite states

OpenAIRE

Jain, Rahul; Shi, Yaoyun; Wei, Zhaohui; Zhang, Shengyu

2012-01-01

We study the correlation complexity (or equivalently, the communication complexity) of generating a bipartite quantum state $\\rho$. When $\\rho$ is a pure state, we completely characterize the complexity for approximately generating $\\rho$ by a corresponding approximate rank, closing a gap left in Ambainis, Schulman, Ta-Shma, Vazirani and Wigderson (SIAM Journal on Computing, 32(6):1570-1585, 2003). When $\\rho$ is a classical distribution $P(x,y)$, we tightly characterize the complexity of gen...

Free-space laser communication technologies; Proceedings of the Meeting, Los Angeles, CA, Jan. 11, 12, 1988

Science.gov (United States)

Koepf, Gerhard A.; Begley, David L.

1988-01-01

The present conference discusses topics in free-space laser communications, laser link characteristics, satellite laser communication systems, optoelectronic components for laser communications, and space laser subsystem technologies. Attention is given to Space Station-based deep-space communication experiments, the application of intersatellite links to operational satellite systems, high-power 0.87 micron channel substrate planar lasers for spaceborne communications, a ground experiment using a CO2 laser transceiver for free-space communications, studies of laser ranging to the TOPEX satellite, diffraction-limited tracking for space communications, and the compact implementation of a real-time, acoustooptic SAR processor.

Space to Space Communication Subsystem Manned Spaceflight and Its Key Technology%载人航天空空通信子系统及其关键技术

Institute of Scientific and Technical Information of China (English)

石云墀

2011-01-01

The composition of the space to space communication subsystem which would realize the transmit the data between Shenzhou spaceship and Tiangong target spacecraft and the functiofi and main performances of the space to space communicator were introduced in this paper. The DS/SS technology which could provide very good performance in anti-jamming and secret communication was applied in the space to space communication subsystem. And the key technologies of sequence synchronization and carrier synchronization in the demodulation of IF DS/SS signal which was the core in DS/SS were analyzed. Using the digital demodulation scheme would reduce the complexity of debugging and increase the reliability of the system.%介绍了实现神舟运输飞船与天宫目标飞行器间数据通信和传输的空空通信子系统的构成，以及空空通信机的功能及其主要性能指标。空空通信子系统采用抗干扰能力强、保密性优的直接序列扩频通信技术。分析了其中的核心中频解扩解调中的伪码同步和载波同步等关键技术，应用数字解调方案降低了子系统调试难度，提高了可靠性。

Quantum communication complexity advantage implies violation of a Bell inequality

NARCIS (Netherlands)

H. Buhrman (Harry); L. Czekaj (Lłukasz); A. Grudka (Andrzej); M. Horodecki (Michalł); P. Horodecki (Pawelł); M. Markiewicz (Marcin); F. Speelman (Florian); S. Strelchuk (Sergii)

2016-01-01

textabstractWe obtain a general connection between a large quantumadvantage in communication complexity and Bell nonlocality. We show that given any protocol offering a sufficiently large quantum advantage in communication complexity, there exists a way of obtaining measurement statistics that

Quantum communication complexity advantage implies violation of a Bell inequality

NARCIS (Netherlands)

H. Buhrman (Harry); L. Czekaj (Lłukasz); A. Grudka (Andrzej); M. Horodecki (Michalł); P. Horodecki (Pawelł); M. Markiewicz (Marcin); F. Speelman (Florian); S. Strelchuk (Sergii)

2015-01-01

htmlabstractWe obtain a general connection between a quantum advantage in communication complexity and non-locality. We show that given any protocol offering a (sufficiently large) quantum advantage in communication complexity, there exists a way of obtaining measurement statistics which violate

Space-Time Code Designs for Broadband Wireless Communications

National Research Council Canada - National Science Library

Xia, Xiang-Gen

2005-01-01

The goal of this research is to design new space AND time codes, such as complex orthogonal space AND time block codes with rate above 1/2 from complex orthogonal designs for QAM, PSK, and CPM signals...

Free Space Optical Communication for Tactical Operations

Science.gov (United States)

2016-09-01

higher energy level to a lower energy level. The photons are focused to optical lenses before transmission into the air medium. The primary purpose...Security of a free space optical transmission . (n.d.). SONA Optical Wireless , [Online]. Available: http://htcbn.com/HTC_Profile_CD/fSONA/APPNOTE...almost always require on-the-move wireless communications. Radio frequency (RF) communication is used to fill the gap, but RF systems are hard pressed to

Taking the Politics Out of Satellite and Space-Based Communications Protocols

Science.gov (United States)

Ivancic, William D.

2006-01-01

After many years of studies, experimentation, and deployment, large amounts of misinformation and misconceptions remain regarding applicability of various communications protocols for use in satellite and space-based networks. This paper attempts to remove much of the politics, misconceptions, and misinformation that have plagued spacebased communications protocol development and deployment. This paper provides a common vocabulary for communications; a general discussion of the requirements for various communication environments; an evaluation of tradeoffs between circuit and packet-switching technologies, and the pros and cons of various link, network, transport, application, and security protocols. Included is the applicability of protocol enhancing proxies to NASA, Department of Defense (DOD), and commercial space communication systems.

[Microsurgical anatomy importance of A1-anterior communicating artery complex].

Science.gov (United States)

Monroy-Sosa, Alejandro; Pérez-Cruz, Julio César; Reyes-Soto, Gervith; Delgado-Hernández, Carlos; Macías-Duvignau, Mario Alberto; Delgado-Reyes, Luis

2013-01-01

The anterior cerebral artery originates from the bifurcation of the internal carotid artery lateral to the optic chiasm, then joins with its contralateral counterpart via the anterior communicating artery. A1-anterior communicating artery complex is the most frequent anatomical variants and is the major site of aneurysms between 30 to 37%. Know the anatomy microsurgical, variants anatomical and importance of complex precommunicating segment-artery anterior communicating in surgery neurological of the pathology vascular, mainly aneurysms, in Mexican population. The study was performed in 30 brains injected. Microanatomy was studied (length and diameter) of A1-anterior communicating artery complex and its variants. 60 segments A1, the average length of left side was 11.35 mm and 11.84 mm was right. The average diameter of left was 1.67 mm and the right was 1.64 mm. The average number of perforators on the left side was 7.9 and the right side was 7.5. Anterior communicating artery was found in 29 brains of the optic chiasm, its course depended on the length of the A1 segment. The average length of the segment was 2.84 mm, the average diameter was 1.41 mm and the average number of perforators was 3.27. A1-anterior communicating artery complex variants were found in 18 (60%) and the presence of two blister-like aneurysms. It is necessary to understand the A1-anterior communicating artery complex microanatomy of its variants to have a three-dimensional vision during aneurysm surgery.

Communication access to businesses and organizations for people with complex communication needs.

Science.gov (United States)

Collier, Barbara; Blackstone, Sarah W; Taylor, Andrew

2012-12-01

Human rights legislation and anti-discrimination and accessibility laws exist in many countries and through international conventions and treaties. To varying degrees, these laws protect the rights of people with disabilities to full and equal access to goods and services. Yet, the accessibility requirements of people with complex communication needs (CCN) are not well represented in the existing accessibility literature. This article describes the results of surveys completed by disability service providers and individuals with CCN due to cerebral palsy, developmental delay, and acquired disabilities. It identifies accessibility requirements for people with CCN for face-to-face communication; comprehension of spoken language; telephone communication; text and print-based communication; Internet, email, and social media interactions; and written communication. Recommendations are made for communication accessibility accommodations in regulations, guidelines, and practices.

Vessel noise cuts down communication space for vocalizing fish and marine mammals.

Science.gov (United States)

Putland, Rosalyn L; Merchant, Nathan D; Farcas, Adrian; Radford, Craig A

2018-04-01

Anthropogenic noise across the world's oceans threatens the ability of vocalizing marine species to communicate. Some species vocalize at key life stages or whilst foraging, and disruption to the acoustic habitat at these times could lead to adverse consequences at the population level. To investigate the risk of these impacts, we investigated the effect of vessel noise on the communication space of the Bryde's whale Balaenoptera edeni, an endangered species which vocalizes at low frequencies, and bigeye Pempheris adspersa, a nocturnal fish species which uses contact calls to maintain group cohesion while foraging. By combining long-term acoustic monitoring data with AIS vessel-tracking data and acoustic propagation modelling, the impact of vessel noise on their communication space was determined. Routine vessel passages cut down communication space by up to 61.5% for bigeyes and 87.4% for Bryde's whales. This influence of vessel noise on communication space exceeded natural variability for between 3.9 and 18.9% of the monitoring period. Additionally, during the closest point of approach of a large commercial vessel, communication space of both species was reduced by a maximum of 99% compared to the ambient soundscape. These results suggest that vessel noise reduces communication space beyond the evolutionary context of these species and may have chronic effects on these populations. To combat this risk, we propose the application or extension of ship speed restrictions in ecologically significant areas, since our results indicate a reduction in sound source levels for vessels transiting at lower speeds. © 2017 John Wiley & Sons Ltd.

Quantum theory in complex Hilbert space

International Nuclear Information System (INIS)

Sharma, C.S.

1988-01-01

The theory of complexification of a real Hilbert space as developed by the author is scrutinized with the aim of explaining why quantum theory should be done in a complex Hilbert space in preference to real Hilbert space. It is suggested that, in order to describe periodic motions in stationary states of a quantum system, the mathematical object modelling a state of a system should have enough points in it to be able to describe explicit time dependence of a periodic motion without affecting the probability distributions of observables. Heuristic evidence for such an assumption comes from Dirac's theory of interaction between radiation and matter. If the assumption is adopted as a requirement on the mathematical model for a quantum system, then a real Hilbert space is ruled out in favour of a complex Hilbert space for a possible model for such a system

Application of spinal code for performance improvement in free-space optical communications

Science.gov (United States)

Saiki, Naoya; Okamoto, Eiji; Takenaka, Hideki; Toyoshima, Morio

2017-09-01

In recent years, the demand for high-capacity communication has grown, and fiber-optic transmission is being used in wired communications to meet this demand. Similarly, free-space optics (FSO), which is an optical wireless communication technology that uses laser light, has attracted much attention and has been considered as a suitable alternative to satisfy this demand in wireless communications. Free-space optical communication uses a hundred THz frequency band and allows for high-speed and radio-regulation free transmission, which may provide a solution for the current shortage of radio frequency bands.

Separations in Communication Complexity Using Cheat Sheets and Information Complexity

NARCIS (Netherlands)

A. Anshu (Anurag); A. Belovs (Aleksandr); S. Ben-David (Shalev); M. Goos (Mika); R. Jain (Rahul); R. Kothari (Robin); T. J. Lee (Troy); M. Santha (Miklos)

2016-01-01

textabstractWhile exponential separations are known between quantum and randomized communication complexity for partial functions (Raz, STOC 1999), the best known separation between these measures for a total function is quadratic, witnessed by the disjointness function. We give the first

Systems and methods for free space optical communication

Science.gov (United States)

Harper, Warren W [Benton City, WA; Aker, Pamela M [Richland, WA; Pratt, Richard M [Richland, WA

2011-05-10

Free space optical communication methods and systems, according to various aspects are described. The methods and systems are characterized by transmission of data through free space with a digitized optical signal acquired using wavelength modulation, and by discrimination between bit states in the digitized optical signal using a spectroscopic absorption feature of a chemical substance.

National Aeronautics and Space Administration plans for space communication technology

Science.gov (United States)

Alexovich, R. E.

1979-01-01

A program plan is presented for a space communications application utilizing the 30/20 GHz frequency bands (30 GHz uplink and 20 GHz downlink). Results of market demand studies and spacecraft systems studies which significantly affect the supporting research and technology program are also presented, along with the scheduled activities of the program plan.

High-capacity Free-space Optical Communications with Orbital Angular Momentum

Data.gov (United States)

National Aeronautics and Space Administration — As the demand for high data returns from space science missions continues, significant improvements over the current radiofrequency (RF) communications architectures...

Complexities of emergency communication: clinicians' perceptions of communication challenges in a trilingual emergency department.

Science.gov (United States)

Pun, Jack Kh; Chan, Engle Angela; Murray, Kristen A; Slade, Diana; Matthiessen, Christian Mim

2017-11-01

To understand the challenges that clinicians face in communicating with patients and other clinicians within a Hong Kong trilingual emergency department. Effective communication has long been recognised as fundamental to the delivery of quality health care, especially in high-risk and time-constrained environments such as emergency departments. The issue of effective communication is particularly relevant in Hong Kong emergency departments, due to the high volume of patients and the linguistic complexity of this healthcare context. In Hong Kong, emergency department clinicians are native speakers of Chinese, but have received their medical training in English. The clinicians read and record virtually all of their medical documentation in English, yet they communicate verbally with patients in Cantonese and Mandarin. In addition, communication between clinicians occurs in spoken Cantonese, mixed with medical English. Thus, medical information is translated numerous times within one patient journey. This complex linguistic environment creates the potential for miscommunication. A mixed-methods design consisting of a quantitative survey with a sequential qualitative interview. Data were collected in a survey from a purposive sample of 58 clinicians and analysed through descriptive statistics. Eighteen of the clinicians were then invited to take part in semi-structured interviews, the data from which were then subjected to a manifest content analysis. Nearly half of the clinicians surveyed believed that medical information may be omitted or altered through repeated translation in a trilingual emergency department. Eighty-three per cent of clinicians stated that there are communication problems at triage. Over 40% said that they have difficulties in documenting medical information. Around 50% believed that long work hours reduced their ability to communicate effectively with patients. In addition, 34% admitted that they rarely or never listen to patients during a

Area, speed and power measurements of FPGA-based complex orthogonal space-time block code channel encoders

Science.gov (United States)

Passas, Georgios; Freear, Steven; Fawcett, Darren

2010-01-01

Space-time coding (STC) is an important milestone in modern wireless communications. In this technique, more copies of the same signal are transmitted through different antennas (space) and different symbol periods (time), to improve the robustness of a wireless system by increasing its diversity gain. STCs are channel coding algorithms that can be readily implemented on a field programmable gate array (FPGA) device. This work provides some figures for the amount of required FPGA hardware resources, the speed that the algorithms can operate and the power consumption requirements of a space-time block code (STBC) encoder. Seven encoder very high-speed integrated circuit hardware description language (VHDL) designs have been coded, synthesised and tested. Each design realises a complex orthogonal space-time block code with a different transmission matrix. All VHDL designs are parameterisable in terms of sample precision. Precisions ranging from 4 bits to 32 bits have been synthesised. Alamouti's STBC encoder design [Alamouti, S.M. (1998), 'A Simple Transmit Diversity Technique for Wireless Communications', IEEE Journal on Selected Areas in Communications, 16:55-108.] proved to be the best trade-off, since it is on average 3.2 times smaller, 1.5 times faster and requires slightly less power than the next best trade-off in the comparison, which is a 3/4-rate full-diversity 3Tx-antenna STBC.

Robust free-space optical communication for indoor information environment

Science.gov (United States)

Nakada, Toyohisa; Itoh, Hideo; Kunifuji, Susumu; Nakashima, Hideyuki

2003-10-01

The purpose of our study is to establish a robust communication, while keeping security and privacy, between a handheld communicator and the surrounding information environment. From the viewpoint of low power consumption, we have been developing a reflectivity modulating communication module composed of a liquid crystal light modulator and a corner-reflecting mirror sheet. We installed a corner-reflecting sheet instead of light scattering sheet in a handheld videogame machine with a display screen with a reflection-type liquid crystal. Infrared (IR) LED illuminator attached next to the IR camera of a base station illuminates all the room, and the terminal send their data to the base station by switching ON and OFF of the reflected IR beam. Intensity of reflected light differs with the position and the direction of the terminal, and sometimes the intensity of OFF signal at a certain condition is brighter than that of ON signal at another condition. To improve the communication quality, use of machine learning technique is a possibility of the solution. In this paper, we compare various machine learning techniques for the purpose of free space optical communication, and propose a new algorithm that improves the robustness of the data link. Evaluation using an actual free-space communication system is also described.

Minimal classical communication and measurement complexity for ...

Indian Academy of Sciences (India)

Minimal classical communication and measurement complexity for quantum ... Entanglement; teleportation; secret sharing; information splitting. ... Ahmedabad 380 009, India; Birla Institute of Technology and Science, Pilani 333 031, India ...

An Introduction to Free-space Optical Communications

Directory of Open Access Journals (Sweden)

H. Henniger

2010-06-01

Full Text Available Over the last two decades free-space optical communication (FSO has become more and more interesting as an adjunct or alternative to radio frequency communication. This article gives an overview of the challenges a system designer has to consider while implementing an FSO system. Typical gains and losses along the path from the transmitter through the medium to the receiver are introduced in this article. Detailed discussions of these topics can be found in this special issue of the Radioengineering Journal.

High Power Uplink Amplifier for Deep Space Communications, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Critical to the success of delivering on the promise of deep space optical communications is the creation of a stable and reliable high power multichannel optical...

High Power Uplink Amplifier for Deep Space Communications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Critical to the success of delivering on the promise of deep space optical communications is the creation of a stable and reliable high power multichannel optical...

Recent Successes and Future Plans for NASA's Space Communications and Navigation Testbed on the International Space Station

Science.gov (United States)

Reinhart, Richard C.; Sankovic, John M.; Johnson, Sandra K.; Lux, James P.; Chelmins, David T.

2014-01-01

Flexible and extensible space communications architectures and technology are essential to enable future space exploration and science activities. NASA has championed the development of the Space Telecommunications Radio System (STRS) software defined radio (SDR) standard and the application of SDR technology to reduce the costs and risks of using SDRs for space missions, and has developed an on-orbit testbed to validate these capabilities. The Space Communications and Navigation (SCaN) Testbed (previously known as the Communications, Navigation, and Networking reConfigurable Testbed (CoNNeCT)) is advancing SDR, on-board networking, and navigation technologies by conducting space experiments aboard the International Space Station. During its first year(s) on-orbit, the SCaN Testbed has achieved considerable accomplishments to better understand SDRs and their applications. The SDR platforms and software waveforms on each SDR have over 1500 hours of operation and are performing as designed. The Ka-band SDR on the SCaN Testbed is NASAs first space Ka-band transceiver and is NASA's first Ka-band mission using the Space Network. This has provided exciting opportunities to operate at Ka-band and assist with on-orbit tests of NASA newest Tracking and Data Relay Satellites (TDRS). During its first year, SCaN Testbed completed its first on-orbit SDR reconfigurations. SDR reconfigurations occur when implementing new waveforms on an SDR. SDR reconfigurations allow a radio to change minor parameters, such as data rate, or complete functionality. New waveforms which provide new capability and are reusable across different missions provide long term value for reconfigurable platforms such as SDRs. The STRS Standard provides guidelines for new waveform development by third parties. Waveform development by organizations other than the platform provider offers NASA the ability to develop waveforms itself and reduce its dependence and costs on the platform developer. Each of these

Research on optic antenna of space laser communication networking

Science.gov (United States)

Meng, Li-Xin; Li, Long; Zhang, Li-zhong; Zhao, Shan-shan; Jiang, Hui-lin

2013-08-01

With the highlights of the high transmission rate, large capacity, strong anti-interference and anti-capture ability, good security and small light, space laser communication becomes an important hotspot. At present, the focus of research of the laser communication system is point to point communication structure. However, from the application point of view, both the realization of space laser communication among multiple points and the establishment of the information transmission network can really have the practical value. Aiming at the problem of space laser communication network, this article puts forward the general idea about optical antenna to achieve multiple tracking goals at the same time. Through the analysis of the optical antenna, and the comparing of the current commonly used mirror driving mechanism, a new mirror driving mechanism is designed. The azimuth motion, containing circular grating feedback, is driven by torque motor，voice coil motor of fan produces pitch motion that has fan-shaped grating feedback, so that compression of the structure size to improve the efficiency of the reflector assembly. Through the establishment of the driving mechanism and the kinematic model of 3D entity, the relationship between the single drive azimuth and pitch angle following the angle of incident light is explained. The biggest ideal view area affecting the optical antenna is obtained by the simulation analysis of the kinematics model using MATLAB. The several factors of field overlap area and blind area offers a theoretical basis for structure optimization and control system for the subsequent optical antenna design.

Asynchronous communication in real space process algebra

NARCIS (Netherlands)

Baeten, J.C.M.; Bergstra, J.A.

1991-01-01

A version of classical real space process algebra is given in which messages travel with constant speed through a three-dimensional medium. It follows that communication is asynchronous and has a broadcasting character. A state operator is used to describe asynchronous message transfer and a

Asynchronous communication in real space process algebra

NARCIS (Netherlands)

Bergstra, J.A.; Baeten, J.C.M.

1992-01-01

A version of classical real space process algebra is given in which messages travel with constant speed through a three-dimensional medium. It follows that communication is asynchronous and has a broadcasting character. A state operator is used to describe asynchronous message transfer and a

Exploring the architectural trade space of NASAs Space Communication and Navigation Program

Science.gov (United States)

Sanchez, M.; Selva, D.; Cameron, B.; Crawley, E.; Seas, A.; Seery, B.

NASAs Space Communication and Navigation (SCaN) Program is responsible for providing communication and navigation services to space missions and other users in and beyond low Earth orbit. The current SCaN architecture consists of three independent networks: the Space Network (SN), which contains the TDRS relay satellites in GEO; the Near Earth Network (NEN), which consists of several NASA owned and commercially operated ground stations; and the Deep Space Network (DSN), with three ground stations in Goldstone, Madrid, and Canberra. The first task of this study is the stakeholder analysis. The goal of the stakeholder analysis is to identify the main stakeholders of the SCaN system and their needs. Twenty-one main groups of stakeholders have been identified and put on a stakeholder map. Their needs are currently being elicited by means of interviews and an extensive literature review. The data will then be analyzed by applying Cameron and Crawley's stakeholder analysis theory, with a view to highlighting dominant needs and conflicting needs. The second task of this study is the architectural tradespace exploration of the next generation TDRSS. The space of possible architectures for SCaN is represented by a set of architectural decisions, each of which has a discrete set of options. A computational tool is used to automatically synthesize a very large number of possible architectures by enumerating different combinations of decisions and options. The same tool contains models to evaluate the architectures in terms of performance and cost. The performance model uses the stakeholder needs and requirements identified in the previous steps as inputs, and it is based in the VASSAR methodology presented in a companion paper. This paper summarizes the current status of the MIT SCaN architecture study. It starts by motivating the need to perform tradespace exploration studies in the context of relay data systems through a description of the history NASA's space communicati

Insectivorous bats respond to vegetation complexity in urban green spaces.

Science.gov (United States)

Suarez-Rubio, Marcela; Ille, Christina; Bruckner, Alexander

2018-03-01

Structural complexity is known to determine habitat quality for insectivorous bats, but how bats respond to habitat complexity in highly modified areas such as urban green spaces has been little explored. Furthermore, it is uncertain whether a recently developed measure of structural complexity is as effective as field-based surveys when applied to urban environments. We assessed whether image-derived structural complexity (MIG) was as/more effective than field-based descriptors in this environment and evaluated the response of insectivorous bats to structural complexity in urban green spaces. Bat activity and species richness were assessed with ultrasonic devices at 180 locations within green spaces in Vienna, Austria. Vegetation complexity was assessed using 17 field-based descriptors and by calculating the mean information gain (MIG) using digital images. Total bat activity and species richness decreased with increasing structural complexity of canopy cover, suggesting maneuverability and echolocation (sensorial) challenges for bat species using the canopy for flight and foraging. The negative response of functional groups to increased complexity was stronger for open-space foragers than for edge-space foragers. Nyctalus noctula , a species foraging in open space, showed a negative response to structural complexity, whereas Pipistrellus pygmaeus , an edge-space forager, was positively influenced by the number of trees. Our results show that MIG is a useful, time- and cost-effective tool to measure habitat complexity that complemented field-based descriptors. Response of insectivorous bats to structural complexity was group- and species-specific, which highlights the need for manifold management strategies (e.g., increasing or reinstating the extent of ground vegetation cover) to fulfill different species' requirements and to conserve insectivorous bats in urban green spaces.

Mitigating Aviation Communication and Satellite Orbit Operations Surprises from Adverse Space Weather

Science.gov (United States)

Tobiska, W. Kent

2008-01-01

Adverse space weather affects operational activities in aviation and satellite systems. For example, large solar flares create highly variable enhanced neutral atmosphere and ionosphere electron density regions. These regions impact aviation communication frequencies as well as precision orbit determination. The natural space environment, with its dynamic space weather variability, is additionally changed by human activity. The increase in orbital debris in low Earth orbit (LEO), combined with lower atmosphere CO2 that rises into the lower thermosphere and causes increased cooling that results in increased debris lifetime, adds to the environmental hazards of navigating in near-Earth space. This is at a time when commercial space endeavors are posed to begin more missions to LEO during the rise of the solar activity cycle toward the next maximum (2012). For satellite and aviation operators, adverse space weather results in greater expenses for orbit management, more communication outages or aviation and ground-based high frequency radio used, and an inability to effectively plan missions or service customers with space-based communication, imagery, and data transferal during time-critical activities. Examples of some revenue-impacting conditions and solutions for mitigating adverse space weather are offered.

Communication in diagnostic radiology: meeting the challenges of complexity.

Science.gov (United States)

Larson, David B; Froehle, Craig M; Johnson, Neil D; Towbin, Alexander J

2014-11-01

As patients and information flow through the imaging process, value is added step-by-step when information is acquired, interpreted, and communicated back to the referring clinician. However, radiology information systems are often plagued with communication errors and delays. This article presents theories and recommends strategies to continuously improve communication in the complex environment of modern radiology. Communication theories, methods, and systems that have proven their effectiveness in other environments can serve as models for radiology.

Free space optical communication

CERN Document Server

Kaushal, Hemani; Kar, Subrat

2017-01-01

This book provides an in-depth understanding of free space optical (FSO) communication with a particular emphasis on optical beam propagation through atmospheric turbulence. The book is structured in such a way that it provides a basic framework for the beginners and also gives a concise description from a designer’s perspective. The book provides an exposure to FSO technology, fundamental limitations, design methodologies, system trade-offs, acquisition, tracking and pointing (ATP) techniques and link-feasibility analysis. The contents of this book will be of interest to professionals and researchers alike. The book may also be used as a textbook for engineering coursework and professional training.

Diaspora: Multilingual and Intercultural Communication across Time and Space

Science.gov (United States)

Wei, Li; Hua, Zhu

2013-01-01

The nature of diaspora is changing in the 21st century. Yet many of the communication issues remain the same. At the heart of it is multilingual and intercultural communication across time and space. There is much that applied linguists can contribute to the understanding of diaspora in the era of globalization. This article discusses some of the…

Near Earth Architectural Options for a Future Deep Space Optical Communications Network

Science.gov (United States)

Edwards, B. L.; Liebrecht, P. E.; Fitzgerald, R. J.

2004-01-01

In the near future the National Aeronautics and Space Administration anticipates a significant increase in demand for long-haul communications services from deep space to Earth. Distances will range from 0.1 to 40 AU, with data rate requirements in the 1's to 1000's of Mbits/second. The near term demand is driven by NASA's Space Science Enterprise which wishes to deploy more capable instruments onboard spacecraft and increase the number of deep space missions. The long term demand is driven by missions with extreme communications challenges such as very high data rates from the outer planets, supporting sub-surface exploration, or supporting NASA's Human Exploration and Development of Space Enterprise beyond Earth orbit. Laser communications is a revolutionary communications technology that will dramatically increase NASA's ability to transmit information across the solar system. Lasercom sends information using beams of light and optical elements, such as telescopes and optical amplifiers, rather than RF signals, amplifiers, and antennas. This paper provides an overview of different network options at Earth to meet NASA's deep space lasercom requirements. It is based mainly on work done for the Mars Laser Communications Demonstration Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It reports preliminary conclusions from the Mars Lasercom Study conducted at MIT/LL and on additional work done for the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telesat Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

Architectural Options for a Future Deep Space Optical Communications Network

Science.gov (United States)

Edwards, B. L.; Benjamin, T.; Scozzafava, J.; Khatri, F.; Sharma, J.; Parvin, B.; Liebrecht, P. E.; Fitzgerald, R. J.

2004-01-01

This paper provides an overview of different options at Earth to provide Deep Space optical communication services. It is based mainly on work done for the Mars Laser Communications Demonstration (MLCD) Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). It also reports preliminary conclusions from the Tracking and Data Relay Satellite System Continuation Study at GSFC. A lasercom flight terminal will be flown on the Mars Telecommunications Orbiter (MTO) to be launched by NASA in 2009, and will be the first high rate deep space demonstration of this revolutionary technology.

Rethinking Communication in Innovation Processes: Creating Space for Change in Complex Systems

NARCIS (Netherlands)

Leeuwis, C.; Aarts, N.

2011-01-01

This paper systematically rethinks the role of communication in innovation processes, starting from largely separate theoretical developments in communication science and innovation studies. Literature review forms the basis of the arguments presented. The paper concludes that innovation is a

Rethinking communication in innovation processes: creating space for change in complex systems

NARCIS (Netherlands)

Leeuwis, C.; Aarts, N.

2011-01-01

This paper systematically rethinks the role of communication in innovation processes, starting from largely separate theoretical developments in communication science and innovation studies. Literature review forms the basis of the arguments presented. The paper concludes that innovation is a

Economic benefits of the Space Station to commercial communication satellite operators

Science.gov (United States)

Price, Kent M.; Dixson, John E.; Weyandt, Charles J.

1987-01-01

The economic and financial aspects of newly defined space-based activities, procedures, and operations (APOs) and associated satellite system designs are presented that have the potential to improve economic performance of future geostationary communications satellites. Launch insurance, launch costs, and the economics of APOs are examined. Retrieval missions and various Space Station scenarios are addressed. The potential benefits of the new APOs to the commercial communications satellite system operator are quantified.

Internet Technologies for Space-based Communications: State of the Art and Challenges

Science.gov (United States)

Bhasin, K.; DePaula, R.; Edwards, C.

2000-01-01

The Internet is rapidly changing the ways we communicate information around the globe today. The desire to provide Internet-based services to anyone, anywhere, anytime has brought satellite communications to the forefront to become an integral part of the Internet. In spite of the distances involved, satellite links are proving to be capable of providing Internet services based on Internet protocol (TCP/IP) stack. This development has led to the question particularly at NASA; can satellites and other space platforms become an Internet-node in space? This will allow the direct transfer of information directly from space to the users on Earth and even be able to control the spacecraft and its instruments. NASA even wants to extend the near earth space Internet to deep space applications where scientists and the public here on Earth may view space exploration in real time via the Internet. NASA's future solar system exploration will involve intensive in situ investigations of planets, moons, asteroids, and comets. While past missions typically involved a single fly-by or orbiting science spacecraft, future missions will begin to use fleets of small, highly intelligent robotic vehicles to carry out collaborative investigations. The resulting multi-spacecraft topologies will effectively create a wide area network spanning the solar system. However, this will require significant development in Internet technologies for space use. This paper provides the status'of the Internet for near earth applications and the potential extension of the Internet for use in deep space planetary exploration. The paper will discuss the overall challenges of implementing the space Internet and how the space Internet will integrate into the complex terrestrial systems those forms the Internet of today in a hybrid set of networks. Internet. We envision extending to the deep space environment such Internet concepts as a well-designed layered architecture. This effort will require an ability to

Online Parent Training to Support Children with Complex Communication Needs

Science.gov (United States)

Douglas, Sarah N.; Nordquist, Erica; Kammes, Rebecca; Gerde, Hope

2017-01-01

Parent training can help support the development of communication skills for young children with complex communication needs (CCN). Online delivery of such training may alleviate some of the burden on families, thereby increasing participation and outcomes. To determine the effectiveness of online parent training in communication partner…

Collective space of high-rise housing complex

Directory of Open Access Journals (Sweden)

Bakaeva Tatyana

2018-01-01

Full Text Available The article considers the problems of support of citizens a comfortable living environment in the conditions of the limited territory of the megalopolis, the typological principles of formation of space-planning structure high-rise residence complexes with public space. The collective space for residents of high-rise housing estates on the example of international experience of design and construction is in detail considered. The collective space and the area of the standard apartment are analysed on comfort classes: a social - complex Pinnacle @ Duxton, a business - Monde Condos and an elite - Hamilton Scotts. Interdependence the area of the standard flat and the total area of housing collective space, in addiction on the comfort level, is revealed. In the conditions of high-density urban development, the collective space allows to form the comfortable environment for accommodation. The recommendations for achievement of integrity and improvement of quality of the city environment are made. The convenient collective space makes a contribution to civil policy, it creates the socializing sense of interaction of residents, coagulates social effect.

Collective space of high-rise housing complex

Science.gov (United States)

Bakaeva, Tatyana

2018-03-01

The article considers the problems of support of citizens a comfortable living environment in the conditions of the limited territory of the megalopolis, the typological principles of formation of space-planning structure high-rise residence complexes with public space. The collective space for residents of high-rise housing estates on the example of international experience of design and construction is in detail considered. The collective space and the area of the standard apartment are analysed on comfort classes: a social - complex Pinnacle @ Duxton, a business - Monde Condos and an elite - Hamilton Scotts. Interdependence the area of the standard flat and the total area of housing collective space, in addiction on the comfort level, is revealed. In the conditions of high-density urban development, the collective space allows to form the comfortable environment for accommodation. The recommendations for achievement of integrity and improvement of quality of the city environment are made. The convenient collective space makes a contribution to civil policy, it creates the socializing sense of interaction of residents, coagulates social effect.

Fractal Complexity-Based Feature Extraction Algorithm of Communication Signals

Science.gov (United States)

Wang, Hui; Li, Jingchao; Guo, Lili; Dou, Zheng; Lin, Yun; Zhou, Ruolin

How to analyze and identify the characteristics of radiation sources and estimate the threat level by means of detecting, intercepting and locating has been the central issue of electronic support in the electronic warfare, and communication signal recognition is one of the key points to solve this issue. Aiming at accurately extracting the individual characteristics of the radiation source for the increasingly complex communication electromagnetic environment, a novel feature extraction algorithm for individual characteristics of the communication radiation source based on the fractal complexity of the signal is proposed. According to the complexity of the received signal and the situation of environmental noise, use the fractal dimension characteristics of different complexity to depict the subtle characteristics of the signal to establish the characteristic database, and then identify different broadcasting station by gray relation theory system. The simulation results demonstrate that the algorithm can achieve recognition rate of 94% even in the environment with SNR of -10dB, and this provides an important theoretical basis for the accurate identification of the subtle features of the signal at low SNR in the field of information confrontation.

Space Mobile Network: A Near Earth Communication and Navigation Architecture

Science.gov (United States)

Israel, Dave J.; Heckler, Greg; Menrad, Robert J.

2016-01-01

This paper describes a Space Mobile Network architecture, the result of a recently completed NASA study exploring architectural concepts to produce a vision for the future Near Earth communications and navigation systems. The Space Mobile Network (SMN) incorporates technologies, such as Disruption Tolerant Networking (DTN) and optical communications, and new operations concepts, such as User Initiated Services, to provide user services analogous to a terrestrial smartphone user. The paper will describe the SMN Architecture, envisioned future operations concepts, opportunities for industry and international collaboration and interoperability, and technology development areas and goals.

Dissipative quantum trajectories in complex space: Damped harmonic oscillator

Energy Technology Data Exchange (ETDEWEB)

Chou, Chia-Chun, E-mail: ccchou@mx.nthu.edu.tw

2016-10-15

Dissipative quantum trajectories in complex space are investigated in the framework of the logarithmic nonlinear Schrödinger equation. The logarithmic nonlinear Schrödinger equation provides a phenomenological description for dissipative quantum systems. Substituting the wave function expressed in terms of the complex action into the complex-extended logarithmic nonlinear Schrödinger equation, we derive the complex quantum Hamilton–Jacobi equation including the dissipative potential. It is shown that dissipative quantum trajectories satisfy a quantum Newtonian equation of motion in complex space with a friction force. Exact dissipative complex quantum trajectories are analyzed for the wave and solitonlike solutions to the logarithmic nonlinear Schrödinger equation for the damped harmonic oscillator. These trajectories converge to the equilibrium position as time evolves. It is indicated that dissipative complex quantum trajectories for the wave and solitonlike solutions are identical to dissipative complex classical trajectories for the damped harmonic oscillator. This study develops a theoretical framework for dissipative quantum trajectories in complex space.

Dissipative quantum trajectories in complex space: Damped harmonic oscillator

International Nuclear Information System (INIS)

Chou, Chia-Chun

2016-01-01

Dissipative quantum trajectories in complex space are investigated in the framework of the logarithmic nonlinear Schrödinger equation. The logarithmic nonlinear Schrödinger equation provides a phenomenological description for dissipative quantum systems. Substituting the wave function expressed in terms of the complex action into the complex-extended logarithmic nonlinear Schrödinger equation, we derive the complex quantum Hamilton–Jacobi equation including the dissipative potential. It is shown that dissipative quantum trajectories satisfy a quantum Newtonian equation of motion in complex space with a friction force. Exact dissipative complex quantum trajectories are analyzed for the wave and solitonlike solutions to the logarithmic nonlinear Schrödinger equation for the damped harmonic oscillator. These trajectories converge to the equilibrium position as time evolves. It is indicated that dissipative complex quantum trajectories for the wave and solitonlike solutions are identical to dissipative complex classical trajectories for the damped harmonic oscillator. This study develops a theoretical framework for dissipative quantum trajectories in complex space.

Free space optical networks for ultra-broad band services

CERN Document Server

Kartalopoulos, Stamatios V

2011-01-01

"Free Space Optical Network is a next generation communication network which uses optical waves instead of microwaves, potentially offering faster communication with ultra band width, meaning more complex communication services can be simultaneously offered. This book describes the network concepts in simple language starting with point-to-point free space optics basics and discusses networking, interoperability with existing communication network, and security. An ideal resource for communication professionals just entering the free space optical communication field and graduate students majoring in optical communications"--Provided by publisher.

Architecture for Cognitive Networking within NASAs Future Space Communications Infrastructure

Science.gov (United States)

Clark, Gilbert J., III; Eddy, Wesley M.; Johnson, Sandra K.; Barnes, James; Brooks, David

2016-01-01

Future space mission concepts and designs pose many networking challenges for command, telemetry, and science data applications with diverse end-to-end data delivery needs. For future end-to-end architecture designs, a key challenge is meeting expected application quality of service requirements for multiple simultaneous mission data flows with options to use diverse onboard local data buses, commercial ground networks, and multiple satellite relay constellations in LEO, MEO, GEO, or even deep space relay links. Effectively utilizing a complex network topology requires orchestration and direction that spans the many discrete, individually addressable computer systems, which cause them to act in concert to achieve the overall network goals. The system must be intelligent enough to not only function under nominal conditions, but also adapt to unexpected situations, and reorganize or adapt to perform roles not originally intended for the system or explicitly programmed. This paper describes architecture features of cognitive networking within the future NASA space communications infrastructure, and interacting with the legacy systems and infrastructure in the meantime. The paper begins by discussing the need for increased automation, including inter-system collaboration. This discussion motivates the features of an architecture including cognitive networking for future missions and relays, interoperating with both existing endpoint-based networking models and emerging information-centric models. From this basis, we discuss progress on a proof-of-concept implementation of this architecture as a cognitive networking on-orbit application on the SCaN Testbed attached to the International Space Station.

Space Link Extension (SLE) Emulation for High-Throughput Network Communication

Science.gov (United States)

Murawski, Robert W.; Tchorowski, Nicole; Golden, Bert

2014-01-01

As the data rate requirements for space communications increases, significant stress is placed not only on the wireless satellite communication links, but also on the ground networks which forward data from end-users to remote ground stations. These wide area network (WAN) connections add delay and jitter to the end-to-end satellite communication link, effects which can have significant impacts on the wireless communication link. It is imperative that any ground communication protocol can react to these effects such that the ground network does not become a bottleneck in the communication path to the satellite. In this paper, we present our SCENIC Emulation Lab testbed which was developed to test the CCSDS SLE protocol implementations proposed for use on future NASA communication networks. Our results show that in the presence of realistic levels of network delay, high-throughput SLE communication links can experience significant data rate throttling. Based on our observations, we present some insight into why this data throttling happens, and trace the probable issue back to non-optimal blocking communication which is sup-ported by the CCSDS SLE API recommended practices. These issues were presented as well to the SLE implementation developers which, based on our reports, developed a new release for SLE which we show fixes the SLE blocking issue and greatly improves the protocol throughput. In this paper, we also discuss future developments for our end-to-end emulation lab and how these improvements can be used to develop and test future space communication technologies.

Level crossing statistics for optical beam wander in a turbulent atmosphere with applications to ground-to-space laser communications.

Science.gov (United States)

Yura, Harold T; Fields, Renny A

2011-06-20

Level crossing statistics is applied to the complex problem of atmospheric turbulence-induced beam wander for laser propagation from ground to space. A comprehensive estimate of the single-axis wander angle temporal autocorrelation function and the corresponding power spectrum is used to develop, for the first time to our knowledge, analytic expressions for the mean angular level crossing rate and the mean duration of such crossings. These results are based on an extension and generalization of a previous seminal analysis of the beam wander variance by Klyatskin and Kon. In the geometrical optics limit, we obtain an expression for the beam wander variance that is valid for both an arbitrarily shaped initial beam profile and transmitting aperture. It is shown that beam wander can disrupt bidirectional ground-to-space laser communication systems whose small apertures do not require adaptive optics to deliver uniform beams at their intended target receivers in space. The magnitude and rate of beam wander is estimated for turbulence profiles enveloping some practical laser communication deployment options and suggesting what level of beam wander effects must be mitigated to demonstrate effective bidirectional laser communication systems.

Complexity in Simplicity: Flexible Agent-based State Space Exploration

DEFF Research Database (Denmark)

Rasmussen, Jacob Illum; Larsen, Kim Guldstrand

2007-01-01

In this paper, we describe a new flexible framework for state space exploration based on cooperating agents. The idea is to let various agents with different search patterns explore the state space individually and communicate information about fruitful subpaths of the search tree to each other...

Free-space laser communication technologies II; Proceedings of the Meeting, Los Angeles, CA, Jan. 15-17, 1990

Science.gov (United States)

Begley, David L. (Editor); Seery, Bernard D. (Editor)

1990-01-01

Various papers on free-space laser communication technologies are presented. Individual topics addressed include: optical intersatellite link experiment between the earth station and ETS-VI, the Goddard optical communications program, technologies and techniques for lasercom terminal size, weight, and cost reduction, laser beam acquisition and tracking system for ETS-VI laser communication equipment, analog dividers for acquisition and tracking signal normalization, fine pointing mechanism using multilayered piezoelectric actuator for optical ISL system, analysis of SILEX tracking sensor performance, new telescope concept for space communication, telescope considered as a very high gain antenna, design of compact transceiver optical systems for optical intersatellite links, ultralightweight optics for laser communications, highly sensitive measurement method for stray light and retroreflected light, depolarization effects on free space laser transceiver communication systems, in-orbit measurements of microaccelerations of ESA's communication satellite Olympus, high-performance laser diode transmitter for optical free space communication, diode-pumped Nd:host laser transmitter for intersatellite optical communications, single-frequency diode-pumped laser for free-space communication.

Programmable High-Rate Multi-Mission Receiver for Space Communications, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Current and upcoming NASA space links require both highly reliable low-rate communications links supporting critical TT&C, ranging and voice services and highly...

Programmable High-Rate Multi-Mission Receiver for Space Communications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Current and upcoming NASA space links require both highly reliable low-rate communications links supporting critical TT&C, ranging and voice services and highly...

Managing Programmatic Risk for Complex Space System Developments

Science.gov (United States)

Panetta, Peter V.; Hastings, Daniel; Brumfield, Mark (Technical Monitor)

2001-01-01

Risk management strategies have become a recent important research topic to many aerospace organizations as they prepare to develop the revolutionary complex space systems of the future. Future multi-disciplinary complex space systems will make it absolutely essential for organizations to practice a rigorous, comprehensive risk management process, emphasizing thorough systems engineering principles to succeed. Project managers must possess strong leadership skills to direct high quality, cross-disciplinary teams for successfully developing revolutionary space systems that are ever increasing in complexity. Proactive efforts to reduce or eliminate risk throughout a project's lifecycle ideally must be practiced by all technical members in the organization. This paper discusses some of the risk management perspectives that were collected from senior managers and project managers of aerospace and aeronautical organizations by the use of interviews and surveys. Some of the programmatic risks which drive the success or failure of projects are revealed. Key findings lead to a number of insights for organizations to consider for proactively approaching the risks which face current and future complex space systems projects.

On imperfect node protection in complex communication networks

International Nuclear Information System (INIS)

Xiao Shi; Xiao Gaoxi

2011-01-01

Motivated by recent research on complex networks, we study enhancing complex communication networks against intentional attack which takes down network nodes in a decreasing order of their degrees. Specifically, we evaluate an effect which has been largely ignored in existing studies; many real-life systems, especially communication systems, have protection mechanisms for their important components. Due to the existence of such protection, it is generally quite difficult to totally crash a protected node, though partially paralyzing it may still be feasible. Our analytical and simulation results show that such 'imperfect' protections generally speaking still help significantly enhance network robustness. Such insight may be helpful for the future developments of efficient network attack and protection schemes.

On imperfect node protection in complex communication networks

Energy Technology Data Exchange (ETDEWEB)

Xiao Shi [Hubei Province Key Laboratory of Intelligent Robot and School of Computer Science and Engineering, Wuhan Institute of Technology, Wuhan 430073 (China); Xiao Gaoxi, E-mail: xiao_moon2002@yahoo.com.cn, E-mail: egxxiao@ntu.edu.sg [Division of Communication Engineering, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 (Singapore)

2011-02-04

Motivated by recent research on complex networks, we study enhancing complex communication networks against intentional attack which takes down network nodes in a decreasing order of their degrees. Specifically, we evaluate an effect which has been largely ignored in existing studies; many real-life systems, especially communication systems, have protection mechanisms for their important components. Due to the existence of such protection, it is generally quite difficult to totally crash a protected node, though partially paralyzing it may still be feasible. Our analytical and simulation results show that such 'imperfect' protections generally speaking still help significantly enhance network robustness. Such insight may be helpful for the future developments of efficient network attack and protection schemes.

A review on channel models in free space optical communication systems

Science.gov (United States)

Anbarasi, K.; Hemanth, C.; Sangeetha, R. G.

2017-12-01

Free Space Optical communication (FSO) is a wireless communication technology which uses light to transmit the data in free space. FSO has advantages like unlicensed spectrum and higher bandwidth. In this paper FSO system merits and demerits, challenges in FSO, and various channel models are discussed. To mitigate the turbulence in FSO the mitigation techniques like relaying, diversity schemes and adopting different modulation techniques used in different channels are discussed and its performance comparison is given.

On deformation of complex continuum immersed in a plane space

Science.gov (United States)

Kovalev, V. A.; Murashkin, E. V.; Radayev, Y. N.

2018-05-01

The present paper is devoted to mathematical modelling of complex continua deformations considered as immersed in an external plane space. The complex continuum is defined as a differential manifold supplied with metrics induced by the external space. A systematic derivation of strain tensors by notion of isometric immersion of the complex continuum into a plane space of a higher dimension is proposed. Problem of establishing complete systems of irreducible objective strain and extrastrain tensors for complex continuum immersed in an external plane space is resolved. The solution to the problem is obtained by methods of the field theory and the theory of rational algebraic invariants. Strain tensors of the complex continuum are derived as irreducible algebraic invariants of contravariant vectors of the external space emerging as functional arguments in the complex continuum action density. Present analysis is restricted to rational algebraic invariants. Completeness of the considered systems of rational algebraic invariants is established for micropolar elastic continua. Rational syzygies for non-quadratic invariants are discussed. Objective strain tensors (indifferent to frame rotations in the external plane space) for micropolar continuum are alternatively obtained by properly combining multipliers of polar decompositions of deformation and extra-deformation gradients. The latter is realized only for continua immersed in a plane space of the equal mathematical dimension.

Passive Thermal Design Approach for the Space Communications and Navigation (SCaN) Testbed Experiment on the International Space Station (ISS)

Science.gov (United States)

Siamidis, John; Yuko, Jim

2014-01-01

The Space Communications and Navigation (SCaN) Program Office at NASA Headquarters oversees all of NASAs space communications activities. SCaN manages and directs the ground-based facilities and services provided by the Deep Space Network (DSN), Near Earth Network (NEN), and the Space Network (SN). Through the SCaN Program Office, NASA GRC developed a Software Defined Radio (SDR) testbed experiment (SCaN testbed experiment) for use on the International Space Station (ISS). It is comprised of three different SDR radios, the Jet Propulsion Laboratory (JPL) radio, Harris Corporation radio, and the General Dynamics Corporation radio. The SCaN testbed experiment provides an on-orbit, adaptable, SDR Space Telecommunications Radio System (STRS) - based facility to conduct a suite of experiments to advance the Software Defined Radio, Space Telecommunications Radio Systems (STRS) standards, reduce risk (Technology Readiness Level (TRL) advancement) for candidate Constellation future space flight hardware software, and demonstrate space communication links critical to future NASA exploration missions. The SCaN testbed project provides NASA, industry, other Government agencies, and academic partners the opportunity to develop and field communications, navigation, and networking technologies in the laboratory and space environment based on reconfigurable, software defined radio platforms and the STRS Architecture.The SCaN testbed is resident on the P3 Express Logistics Carrier (ELC) on the exterior truss of the International Space Station (ISS). The SCaN testbed payload launched on the Japanese Aerospace Exploration Agency (JAXA) H-II Transfer Vehicle (HTV) and was installed on the ISS P3 ELC located on the inboard RAM P3 site. The daily operations and testing are managed out of NASA GRC in the Telescience Support Center (TSC).

Quaternionic formulation of tachyons, superluminal transformations and a complex space-time

Energy Technology Data Exchange (ETDEWEB)

Imaeda, K [Dublin Inst. for Advanced Studies (Ireland)

1979-04-11

A theory of tachyons and superluminal transformations is developed on the basis of the quaternionic formulation. A complex space-time adn a complex transformation group which contains both Lorentz transformations and superluminal transformations are introduced. The complex space-time '' the biquaternion space'' which is closed under the superluminal transformations is introduced. The principle of special relativity, such as the conservation of the quadratic form of the metric of the space-time, and the principle of duality are extended to the complex space-time and to bradyons, luxons and tachyons under the complex transformations. SeVeral characteristic features of the superluminal transformations and of tachyons are derived.

Therapeutic communication and relationships in chronic and complex care.

Science.gov (United States)

Brownie, Sharon; Scott, Robin; Rossiter, Rachel

2016-10-05

As the population ages and the incidence of chronic diseases and lifestyle-related conditions rises, nurses are increasingly required to provide care for people with a range of chronic (long-term) conditions. The healthcare needs of patients are often complicated by comorbid conditions. Nurses deliver healthcare in the context of the patient's medical conditions, treatment regimens, the healthcare system, and the individual's socioeconomic, personal and family factors, which may include the challenges of social isolation and geographic distance. In such complex circumstances, patients may be perceived as 'difficult' or 'challenging', however, the challenge is not the patient themselves, but the relationship between the nurse and the patient. Communication difficulties can occur between nurses and patients, which may affect the therapeutic relationship and the quality of care provided. This article discusses the communication skills that nurses require to interact effectively with patients who have complex and chronic comorbid conditions. It focuses on therapeutic communication strategies and the nurse-patient relationship, while emphasising the need for nurses to be self-aware when caring for patients with complex healthcare needs.

Complexity theory in the management of communicable diseases.

Science.gov (United States)

Simmons, Mike

2003-06-01

In nature, apparently complex behavioural patterns are the result of repetitive simple rules. Complexity science studies the application of these rules and looks for applications in society. Complexity management opportunities have developed from this science and are providing a revolutionary approach in the constantly changing workplace. This article discusses how complexity management techniques have already been applied to communicable disease management in Wales and suggests further developments. A similar approach is recommended to others in the field, while complexity management probably has wider applications in the NHS, not least in relation to the developing managed clinical networks.

Deep space optical communication via relay satellite

Science.gov (United States)

Dolinar, S.; Vilnrotter, V.; Gagliardi, R.

1981-01-01

The application of optical communications for a deep space link via an earth-orbiting relay satellite is discussed. The system uses optical frequencies for the free-space channel and RF links for atmospheric transmission. The relay satellite is in geostationary orbit and contains the optics necessary for data processing and formatting. It returns the data to earth through the RF terrestrial link and also transmits an optical beacon to the satellite for spacecraft return pointing and for the alignment of the transmitting optics. Future work will turn to modulation and coding, pointing and tracking, and optical-RF interfacing.

Space Tweetup - from a participant to a Mars Tweetup organizer and a new format of space communication

Science.gov (United States)

Haider, O.; Groemer, G.

2014-01-01

In September 2011, the European Space Agency (ESA) and the German Space Agency (DLR) organized the first European SpaceTweetup during the German Aerospace day. One of the authors was one of 60 participants at this SpaceTweetup in Cologne and experienced the concept of a Tweetup and the engagement of the participants from the inside view. Building upon this experience, the Austrian Space Forum (OeWF) organized the first Austrian MarsTweetup during the “Dachstein Mars analog simulation”. Between 27 Apr,2001 and May,2012, a five day Mars simulation was conducted by the Austrian Space Forum and international research partners at the Giant Ice caves at the Dachstein region in Austria. During this field test, the Aouda.X spacesuit simulator and selected geophysical and life-science related experiments were conducted. In this paper we outline the potential and limitations of social media and how to engage the general public to participate and communicate about space projects through their own experience. We show examples of material SpaceTweetup participants produced e.g. hundreds of tweets during the actual event, blog entries, photo galleries and how space communication can benefit from it. Our considerations on organizing a SpaceTweetup are complemented with a section on lessons learned.

Variable Coding and Modulation Experiment Using NASA's Space Communication and Navigation Testbed

Science.gov (United States)

Downey, Joseph A.; Mortensen, Dale J.; Evans, Michael A.; Tollis, Nicholas S.

2016-01-01

National Aeronautics and Space Administration (NASA)'s Space Communication and Navigation Testbed on the International Space Station provides a unique opportunity to evaluate advanced communication techniques in an operational system. The experimental nature of the Testbed allows for rapid demonstrations while using flight hardware in a deployed system within NASA's networks. One example is variable coding and modulation, which is a method to increase data-throughput in a communication link. This paper describes recent flight testing with variable coding and modulation over S-band using a direct-to-earth link between the SCaN Testbed and the Glenn Research Center. The testing leverages the established Digital Video Broadcasting Second Generation (DVB-S2) standard to provide various modulation and coding options. The experiment was conducted in a challenging environment due to the multipath and shadowing caused by the International Space Station structure. Performance of the variable coding and modulation system is evaluated and compared to the capacity of the link, as well as standard NASA waveforms.

The effect of jitter on the performance of space coherent optical communication system with Costas loop

Science.gov (United States)

Li, Xin; Hong, Yifeng; Wang, Jinfang; Liu, Yang; Sun, Xun; Li, Mi

2018-01-01

Numerous communication techniques and optical devices successfully applied in space optical communication system indicates a good portability of it. With this good portability, typical coherent demodulation technique of Costas loop can be easily adopted in space optical communication system. As one of the components of pointing error, the effect of jitter plays an important role in the communication quality of such system. Here, we obtain the probability density functions (PDF) of different jitter degrees and explain their essential effect on the bit error rate (BER) space optical communication system. Also, under the effect of jitter, we research the bit error rate of space coherent optical communication system using Costas loop with different system parameters of transmission power, divergence angle, receiving diameter, avalanche photodiode (APD) gain, and phase deviation caused by Costas loop. Through a numerical simulation of this kind of communication system, we demonstrate the relationship between the BER and these system parameters, and some corresponding methods of system optimization are presented to enhance the communication quality.

LEO-to-ground optical communications using SOTA (Small Optical TrAnsponder) - Payload verification results and experiments on space quantum communications

Science.gov (United States)

Carrasco-Casado, Alberto; Takenaka, Hideki; Kolev, Dimitar; Munemasa, Yasushi; Kunimori, Hiroo; Suzuki, Kenji; Fuse, Tetsuharu; Kubo-Oka, Toshihiro; Akioka, Maki; Koyama, Yoshisada; Toyoshima, Morio

2017-10-01

Free-space optical communications have held the promise of revolutionizing space communications for a long time. The benefits of increasing the bitrate while reducing the volume, mass and energy of the space terminals have attracted the attention of many researchers for a long time. In the last few years, more and more technology demonstrations have been taking place with participants from both the public and the private sector. The National Institute of Information and Communications Technology (NICT) in Japan has a long experience in this field. SOTA (Small Optical TrAnsponder) was the last NICT space lasercom mission, designed to demonstrate the potential of this technology applied to microsatellites. Since the beginning of SOTA mission in 2014, NICT regularly established communication using the Optical Ground Stations (OGS) located in the Headquarters at Koganei (Tokyo) to receive the SOTA signals, with over one hundred successful links. All the goals of the SOTA mission were fulfilled, including up to 10-Mbit/s downlinks using two different wavelengths and apertures, coarse and fine tracking of the OGS beacon, space-to-ground transmission of the on-board-camera images, experiments with different error correcting codes, interoperability with other international OGS, and experiments on quantum communications. The SOTA mission ended on November 2016, more than doubling the designed lifetime of 1-year. In this paper, the SOTA characteristics and basic operation are explained, along with the most relevant technological demonstrations.

Architecture for Cognitive Networking within NASA's Future Space Communications Infrastructure

Science.gov (United States)

Clark, Gilbert; Eddy, Wesley M.; Johnson, Sandra K.; Barnes, James; Brooks, David

2016-01-01

Future space mission concepts and designs pose many networking challenges for command, telemetry, and science data applications with diverse end-to-end data delivery needs. For future end-to-end architecture designs, a key challenge is meeting expected application quality of service requirements for multiple simultaneous mission data flows with options to use diverse onboard local data buses, commercial ground networks, and multiple satellite relay constellations in LEO, GEO, MEO, or even deep space relay links. Effectively utilizing a complex network topology requires orchestration and direction that spans the many discrete, individually addressable computer systems, which cause them to act in concert to achieve the overall network goals. The system must be intelligent enough to not only function under nominal conditions, but also adapt to unexpected situations, and reorganize or adapt to perform roles not originally intended for the system or explicitly programmed. This paper describes an architecture enabling the development and deployment of cognitive networking capabilities into the envisioned future NASA space communications infrastructure. We begin by discussing the need for increased automation, including inter-system discovery and collaboration. This discussion frames the requirements for an architecture supporting cognitive networking for future missions and relays, including both existing endpoint-based networking models and emerging information-centric models. From this basis, we discuss progress on a proof-of-concept implementation of this architecture, and results of implementation and initial testing of a cognitive networking on-orbit application on the SCaN Testbed attached to the International Space Station.

Status of High Data Rate Intersatellite Laser Communication as an Enabler for Earth and Space Science

Science.gov (United States)

Heine, F.; Zech, H.; Motzigemba, M.

2017-12-01

Space based laser communication is supporting earth observation and science missions with Gbps data download capabilities. Currently the Sentinel 1 and Sentinel 2 spacecrafts from the Copernicus earth observation program of the European Commission are using the Gbps laser communication links developed by Tesat Spacecom to download low latency data products via a commercial geostationary laser relay station- the European Data Relay Service- (EDRS) as a standard data path, in parallel to the conventional radio frequency links. The paper reports on the status of high bandwidth space laser communication as an enabler for small and large space science missions ranging from cube sat applications in low earth orbit to deep space missions. Space based laser communication has left the experimental phase and will support space science missions with unprecedented data rates.

Examination of Communication Delays on Team Performance: Utilizing the International Space Station (ISS) as a Test Bed for Analog Research

Science.gov (United States)

Keeton, K. E.; Slack, K, J.; Schmidt, L. L.; Ploutz-Snyder, R.; Baskin, P.; Leveton, L. B.

2011-01-01

Operational conjectures about space exploration missions of the future indicate that space crews will need to be more autonomous from mission control and operate independently. This is in part due to the expectation that communication quality between the ground and exploration crews will be more limited and delayed. Because of potential adverse effects on communication quality, both researchers and operational training and engineering experts have suggested that communication delays and the impact these delays have on the quality of communications to the crew will create performance decrements if crews are not given adequate training and tools to support more autonomous operations. This presentation will provide an overview of a research study led by the Behavioral Health and Performance Element (BHP) of the NASA Human Research Program that examines the impact of implementing a communication delay on ISS on individual and team factors and outcomes, including performance and related perceptions of autonomy. The methodological design, data collection efforts, and initial results of this study to date will be discussed . The results will focus on completed missions, DRATS and NEEMO15. Lessons learned from implementing this study within analog environments will also be discussed. One lesson learned is that the complexities of garnishing a successful data collection campaign from these high fidelity analogs requires perseverance and a strong relationship with operational experts. Results of this study will provide a preliminary understanding of the impact of communication delays on individual and team performance as well as an insight into how teams perform and interact in a space-like environment . This will help prepare for implementation of communication delay tests on the ISS, targeted for Increment 35/36.

Space Weather effects on airline communications in the high latitude regions

Science.gov (United States)

Honary, Farideh

2014-05-01

Efficient air traffic management depends on reliable communications between aircraft and the air traffic control centres at all times. At high latitudes, and especially on polar routing, VHF ground infrastructure does not exist and the aircraft have to rely on HF radio for communications. HF relies on reflections from the ionosphere to achieve long distance communications. Unfortunately the high latitude ionosphere is affected by space weather events. During such events HF radio communication can be severely disrupted and aircraft are forced to use longer low latitude routes with consequent increased flight time, fuel consumption and cost. This presentation describes a new research programme at the University of Lancaster in collaboration with the University of Leicester, Solar Metrics Ltd and Natural Resources Canada for the development of a nowcasting and forecasting HF communications tool designed for the particular needs of civilian airlines. This project funded by EPSRC will access a wide variety of solar and interplanetary measurements to derive a complete picture of space weather disturbances affecting radio absorption and reflection

Mixed Integer Programming and Heuristic Scheduling for Space Communication

Science.gov (United States)

Lee, Charles H.; Cheung, Kar-Ming

2013-01-01

Optimal planning and scheduling for a communication network was created where the nodes within the network are communicating at the highest possible rates while meeting the mission requirements and operational constraints. The planning and scheduling problem was formulated in the framework of Mixed Integer Programming (MIP) to introduce a special penalty function to convert the MIP problem into a continuous optimization problem, and to solve the constrained optimization problem using heuristic optimization. The communication network consists of space and ground assets with the link dynamics between any two assets varying with respect to time, distance, and telecom configurations. One asset could be communicating with another at very high data rates at one time, and at other times, communication is impossible, as the asset could be inaccessible from the network due to planetary occultation. Based on the network's geometric dynamics and link capabilities, the start time, end time, and link configuration of each view period are selected to maximize the communication efficiency within the network. Mathematical formulations for the constrained mixed integer optimization problem were derived, and efficient analytical and numerical techniques were developed to find the optimal solution. By setting up the problem using MIP, the search space for the optimization problem is reduced significantly, thereby speeding up the solution process. The ratio of the dimension of the traditional method over the proposed formulation is approximately an order N (single) to 2*N (arraying), where N is the number of receiving antennas of a node. By introducing a special penalty function, the MIP problem with non-differentiable cost function and nonlinear constraints can be converted into a continuous variable problem, whose solution is possible.

Superconducting Nanowire Single Photon Detectors for High-Data-Rate Deep-Space Optical Communication

Data.gov (United States)

National Aeronautics and Space Administration — High data rate deep space optical communication (DSOC) links for manned and unmanned space exploration have been identified by NASA as a critical future capability,...

Space Communications and Data Systems Technologies for Next Generation Earth Science Measurements

Science.gov (United States)

Bauer, Robert A.; Reinhart, Richard C.; Hilderman, Don R.; Paulsen, Phillip E.

2003-01-01

The next generation of Earth observing satellites and sensor networks will face challenges in supporting robust high rate communications links from the increasingly sophisticated onboard instruments. Emerging applications will need data rates forecast to be in the 100's to 1000's of Mbps. As mission designers seek smaller spacecraft, challenges exist in reducing the size and power requirements while increasing the capacity of the spacecraft's communications technologies. To meet these challenges, this work looks at three areas of selected space communications and data services technologies, specifically in the development of reflectarray antennas, demonstration of space Internet concepts, and measurement of atmospheric propagation effects on Ka-band signal transmitted from LEO.

Free-Space Quantum Communication with a Portable Quantum Memory

Science.gov (United States)

Namazi, Mehdi; Vallone, Giuseppe; Jordaan, Bertus; Goham, Connor; Shahrokhshahi, Reihaneh; Villoresi, Paolo; Figueroa, Eden

2017-12-01

The realization of an elementary quantum network that is intrinsically secure and operates over long distances requires the interconnection of several quantum modules performing different tasks. In this work, we report the realization of a communication network functioning in a quantum regime, consisting of four different quantum modules: (i) a random polarization qubit generator, (ii) a free-space quantum-communication channel, (iii) an ultralow-noise portable quantum memory, and (iv) a qubit decoder, in a functional elementary quantum network possessing all capabilities needed for quantum-information distribution protocols. We create weak coherent pulses at the single-photon level encoding polarization states |H ⟩ , |V ⟩, |D ⟩, and |A ⟩ in a randomized sequence. The random qubits are sent over a free-space link and coupled into a dual-rail room-temperature quantum memory and after storage and retrieval are analyzed in a four-detector polarization analysis akin to the requirements of the BB84 protocol. We also show ultralow noise and fully portable operation, paving the way towards memory-assisted all-environment free-space quantum cryptographic networks.

High-Efficiency, High-Power Laser Transmitter for Deep-Space Communication, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — There is demand for vastly improved deep space satellite communications links. As data rates dramatically increase due to new sensor technologies and the desire to...

Highly Sensitive Photon Counting Detectors for Deep Space Optical Communications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A new type of a photon-counting photodetector is proposed to advance the state-of the-art in deep space optical communications technology. The proposed detector...

TRENDS IN THE DEVELOPMENT OF MARKETING COMMUNICATIONS IN THE GLOBAL INTERACTIVE SPACE

Directory of Open Access Journals (Sweden)

N. Kochkina

2014-09-01

Full Text Available The article identifies trends in the development of marketing communications in the global interactive space by analyzing the factors of their functioning and researching motivation of viral audience. It is revealed the prevalence of interactive technologies in today's information space and the growth dynamics of interactive advertising market. It is proved that favorable conditions for marketing communications' functioning forms the basis for the development of viral advertising as an effective communication tool for untraditional impact on potential customers. The popularity of social networks as a major source of viral messages is determined. The motivation of YouTube audience, which provides a resonant video viewing and retransmission, is investigated. Gender and age differences that stipulate communication affect on consumers are identified. Cyclic social consciousness is observed that demands further research of viral audience, including constructing scenarios of viral behavior.

Free Space Optics Communication for Mobile Military Platforms

Science.gov (United States)

2003-12-01

Federal Communications Commission FDA Food and Drug Administration FOV Field-of-View FSO Free Space Optics FWHM Full Width at Half Maximum Gbps...Physique et de Métrologie des Oscillateurs (LPMO) du CNRS UPR3203, associé à l’Université de Franche -Comté, 15 March 2002 [Schenk 2000] H. Schenk

A Study for Optimum Space-to-Ground Communication Concept for CubeSat and SmallSat Platforms

Data.gov (United States)

National Aeronautics and Space Administration — This study is to explore the communication architecture for future space-to-ground CubeSat/SmallSat communication, through simulations, analyses, and identifying...

Asynchronous communication in real space process algebra

OpenAIRE

Baeten, JCM Jos; Bergstra, JA Jan

1990-01-01

A version of classical real space process algebra is given in which messages travel with constant speed through a three-dimensional medium. It follows that communication is asynchronous and has a broadcasting character. A state operator is used to describe asynchronous message transfer and a priority mechanism allows to express the broadcasting mechanism. As an application, a protocol is specified in which the receiver moves with respect to the sender.

Free-space laser communication technologies III; Proceedings of the Meeting, Los Angeles, CA, Jan. 21, 22, 1991

Science.gov (United States)

Begley, David L. (Editor); Seery, Bernard D. (Editor)

1991-01-01

The present volume on free-space laser communication technologies discusses system analysis, performance, and applications, pointing, acquisition, and tracking in beam control, laboratory demonstration systems, and transmitter and critical component technologies. Attention is given to a space station laser communication transceiver, meeting intersatellite links mission requirements by an adequate optical terminal design, an optical approach to proximity-operations communications for Space Station Freedom, and optical space-to-ground link availability assessment and diversity requirements. Topics addressed include nonmechanical steering of laser beams by multiple aperture antennas, a free-space simulator for laser transmission, heterodyne acquisition and tracking in a free-space diode laser link, and laser terminal attitude determination via autonomous star tracking. Also discussed are stability considerations in relay lens design for optical communications, liquid crystals for lasercom applications, and narrowband optical interference filters.

Characterization of the Marine Atmosphere for Free-Space Optical Communication

National Research Council Canada - National Science Library

Thomas, Linda M. Wasiczko; Moore, Christopher I; Burris, Harris R; Suite, Michele; Stell, Mena; Murphy, James; Gilbreath, G. C; Rabinovich, William; Scharpf, William

2006-01-01

The Chesapeake Bay Detachment of the Naval Research Laboratory (NRL-CBD) provides an ideal environment for characterizing the effects of the marine atmosphere on free space optical communication links...

High-dimensional free-space optical communications based on orbital angular momentum coding

Science.gov (United States)

Zou, Li; Gu, Xiaofan; Wang, Le

2018-03-01

In this paper, we propose a high-dimensional free-space optical communication scheme using orbital angular momentum (OAM) coding. In the scheme, the transmitter encodes N-bits information by using a spatial light modulator to convert a Gaussian beam to a superposition mode of N OAM modes and a Gaussian mode; The receiver decodes the information through an OAM mode analyser which consists of a MZ interferometer with a rotating Dove prism, a photoelectric detector and a computer carrying out the fast Fourier transform. The scheme could realize a high-dimensional free-space optical communication, and decodes the information much fast and accurately. We have verified the feasibility of the scheme by exploiting 8 (4) OAM modes and a Gaussian mode to implement a 256-ary (16-ary) coding free-space optical communication to transmit a 256-gray-scale (16-gray-scale) picture. The results show that a zero bit error rate performance has been achieved.

An examination of relations between participation, communication and age in children with complex communication needs.

Science.gov (United States)

Clarke, Michael; Newton, Caroline; Petrides, Konstantinos; Griffiths, Tom; Lysley, Andrew; Price, Katie

2012-03-01

The aim of this study was to examine variation in the frequency of children's participation in out-of-school activities as a function of speech intelligibility, perceived effectiveness of the child's communication aid, and age. Sixty-nine caregivers of children with complex communication needs provided with communication aids completed a questionnaire survey. Rate of participation was higher for younger than for older children, particularly in recreational activities. Younger children with partial intelligibility participated more frequently in recreational and social activities than both younger children without speech and older children. Results and limitations are discussed within the context of participation research in childhood disability, highlighting the impact of communicative resources and maturation on everyday participation.

Quantum cryptography for secure free-space communications

International Nuclear Information System (INIS)

Hughes, R.J.; Buttler, W.T.; Kwiat, P.G.; Lamoreaux, S.K.; Luther, G.G.; Morgan, G.L.; Nordholt, J.E.; Peterson, C.G.

1999-01-01

The secure distribution of the secret random bit sequences known as key material, is an essential precursor to their use for the encryption and decryption of confidential communications. Quantum cryptography is a new technique for secure key distribution with single-photon transmissions: Heisenberg's uncertainty principle ensures that an adversary can neither successfully tap the key transmissions, nor evade detection (eavesdropping raises the key error rate above a threshold value). The authors have developed experimental quantum cryptography systems based on the transmission of non-orthogonal photon polarization states to generate shared key material over line-of-sight optical links. Key material is built up using the transmission of a single-photon per bit of an initial secret random sequence. A quantum-mechanically random subset of this sequence is identified, becoming the key material after a data reconciliation stage with the sender. The authors have developed and tested a free-space quantum key distribution (QKD) system over an outdoor optical path of ∼1 km at Los Alamos National Laboratory under nighttime conditions. Results show that free-space QKD can provide secure real-time key distribution between parties who have a need to communicate secretly. Finally, they examine the feasibility of surface to satellite QKD

Mastery motivation in children with complex communication needs: longitudinal data analysis.

Science.gov (United States)

Medeiros, Kara F; Cress, Cynthia J; Lambert, Matthew C

2016-09-01

This study compared longitudinal changes in mastery motivation during parent-child free play for 37 children with complex communication needs. Mastery motivation manifests as a willingness to work hard at tasks that are challenging, which is an important quality to overcoming the challenges involved in successful expressive communication using AAC. Unprompted parent-child play episodes were identified in three assessment sessions over an 18-month period and coded for nine categories of mastery motivation in social and object play. All of the object-oriented mastery motivation categories and one social mastery motivation category showed an influence of motor skills after controlling for receptive language. Object play elicited significantly more of all of the object-focused mastery motivation categories than social play, and social play elicited more of one type of social-focused mastery motivation behavior than object play. Mastery motivation variables did not differ significantly over time for children. Potential physical and interpersonal influences on mastery motivation for parents and children with complex communication needs are discussed, including broadening the procedures and definitions of mastery motivation beyond object-oriented measurements for children with complex communication needs.

Secure space-to-space interferometric communications and its nexus to the physics of quantum entanglement

Science.gov (United States)

Duarte, F. J.

2016-12-01

The history of the probability amplitude equation | ψ > = ( | x , y > - | y , x > ) applicable to quanta pairs, propagating in different directions with entangled polarizations, is reviewed and traced back to the 1947-1949 period. The interferometric Dirac foundations common to | ψ > = ( | x , y > - | y , x > ) and the generalized N-slit interferometric equation, for indistinguishable quanta, are also described. The results from a series of experiments on N-slit laser interferometers, with intra interferometric propagation paths up to 527 m, are reviewed. Particular attention is given to explain the generation of interferometric characters, for secure space-to-space communications, which immediately collapse on attempts of interception. The design of a low divergence N-slit laser interferometer for low Earth orbit-low Earth orbit (LEO-LEO), and LEO-geostationary Earth orbit (LEO-GEO), secure interferometric communications is described and a weight assessment is provided.

The Process of Science Communications at NASA/Marshall Space Flight Center

Science.gov (United States)

Horack, John M.; Treise, Deborah

1998-01-01

The communication of new scientific knowledge and understanding is an integral component of science research, essential for its continued survival. Like any learning- based activity, science cannot continue without communication between and among peers so that skeptical inquiry and learning can take place. This communication provides necessary organic support to maintain the development of new knowledge and technology. However, communication beyond the peer-community is becoming equally critical for science to survive as an enterprise into the 21st century. Therefore, scientists not only have a 'noble responsibility' to advance and communicate scientific knowledge and understanding to audiences within and beyond the peer-community, but their fulfillment of this responsibility is necessary to maintain the survival of the science enterprise. Despite the critical importance of communication to the viability of science, the skills required to perform effective science communications historically have not been taught as a part of the training of scientist, and the culture of science is often averse to significant communication beyond the peer community. Thus scientists can find themselves ill equipped and uncomfortable with the requirements of their job in the new millennium. At NASA/Marshall Space Flight Center, we have developed and implemented an integrated science communications process, providing an institutional capability to help scientist accurately convey the content and meaning of new scientific knowledge to a wide variety of audiences, adding intrinsic value to the research itself through communication, while still maintaining the integrity of the peer-review process. The process utilizes initial communication through the world-wide web at the site http://science.nasa.gov to strategically leverage other communications vehicles and to reach a wide-variety of audiences. Here we present and discuss the basic design of the science communications process, now in

Adaptive Coding and Modulation Experiment With NASA's Space Communication and Navigation Testbed

Science.gov (United States)

Downey, Joseph; Mortensen, Dale; Evans, Michael; Briones, Janette; Tollis, Nicholas

2016-01-01

National Aeronautics and Space Administration (NASA)'s Space Communication and Navigation Testbed is an advanced integrated communication payload on the International Space Station. This paper presents results from an adaptive coding and modulation (ACM) experiment over S-band using a direct-to-earth link between the SCaN Testbed and the Glenn Research Center. The testing leverages the established Digital Video Broadcasting Second Generation (DVB-S2) standard to provide various modulation and coding options, and uses the Space Data Link Protocol (Consultative Committee for Space Data Systems (CCSDS) standard) for the uplink and downlink data framing. The experiment was conducted in a challenging environment due to the multipath and shadowing caused by the International Space Station structure. Several approaches for improving the ACM system are presented, including predictive and learning techniques to accommodate signal fades. Performance of the system is evaluated as a function of end-to-end system latency (round-trip delay), and compared to the capacity of the link. Finally, improvements over standard NASA waveforms are presented.

Period mappings with applications to symplectic complex spaces

CERN Document Server

Kirschner, Tim

2015-01-01

Extending Griffiths’ classical theory of period mappings for compact Kähler manifolds, this book develops and applies a theory of period mappings of “Hodge-de Rham type” for families of open complex manifolds. The text consists of three parts. The first part develops the theory. The second part investigates the degeneration behavior of the relative Frölicher spectral sequence associated to a submersive morphism of complex manifolds. The third part applies the preceding material to the study of irreducible symplectic complex spaces. The latter notion generalizes the idea of an irreducible symplectic manifold, dubbed an irreducible hyperkähler manifold in differential geometry, to possibly singular spaces. The three parts of the work are of independent interest, but intertwine nicely.

NASA space communications R and D (Research and Development): Issues, derived benefits, and future directions

Science.gov (United States)

1989-02-01

Space communication is making immense strides since ECHO was launched in 1962. It was a simple passive reflector of signals that demonstrated the concept. Today, satellites incorporating transponders, sophisticated high-gain antennas, and stabilization systems provide voice, video, and data communications to millions of people nationally and worldwide. Applications of emerging technology, typified by NASA's Advanced Communications Technology Satellite (ACTS) to be launched in 1992, will use newer portions of the frequency spectrum (the Ka-band at 30/20 GHz), along with antennas and signal-processing that could open yet new markets and services. Government programs, directly or indirectly, are responsible for many space communications accomplishments. They are sponsored and funded in part by NASA and the U.S. Department of Defense since the early 1950s. The industry is growing rapidly and is achieving international preeminence under joint private and government sponsorship. Now, however, the U.S. space communications industry - satellite manufacturers and users, launch services providers, and communications services companies - are being forced to adapt to a different environment. International competition is growing, and terrestrial technologies such as fiber optics are claiming markets until recently dominated by satellites. At the same time, advancing technology is opening up opportunities for new applications and new markets in space exploration, for defense, and for commercial applications of several types. Space communications research, development, and applications (RD and A) programs need to adjust to these realities, be better coordinated and more efficient, and be more closely attuned to commercial markets. The programs must take advantage of RD and A results in other agencies - and in other nations.

Obstacle evasion in free-space optical communications utilizing Airy beams

Science.gov (United States)

Zhu, Guoxuan; Wen, Yuanhui; Wu, Xiong; Chen, Yujie; Liu, Jie; Yu, Siyuan

2018-03-01

A high speed free-space optical communication system capable of self-bending signal transmission around line-of-sight obstacles is proposed and demonstrated. Airy beams are generated and controlled to achieve different propagating trajectories, and the signal transmission characteristics of these beams around the obstacle are investigated. Our results confirm that, by optimising their ballistic trajectories, Airy beams are able to bypass obstacles with more signal energy and thus improve the communication performance compared with normal Gaussian beams.

Precoded generalized space shift keying for indoor visible light communications

KAUST Repository

Kadampot, Ishaque Ashar; Park, Kihong; Alouini, Mohamed-Slim

2014-01-01

We consider a visible light communication system with 2 transmit light emitting diodes (LED) and nr receive photodiodes. An optical generalized space shift keying modulation scheme is considered for the transmission of bits where each LED can

The Complexity Paradigm for Studying Human Communication: A Summary and Integration of Two Fields

Directory of Open Access Journals (Sweden)

John Sherry

2015-01-01

Full Text Available This popular quote from Hamlet might be recast for the field of communication as “There are more things in science than are dreamt of in our philosophies”. This article will review several new and strange ideas from complexity science about how the natural world is organized and how we can go about researching it. These strange ideas, (e.g., deterministic, but unpredictable systems resonate with many communication phenomena that our field has traditionally had difficulty studying. By reviewing these areas, we hope to add a new, compelling and useful way to think about science that goes beyond the current dominant philosophy of science employed in communication. Though the concepts reviewed here are difficult and often appear at odds with the dominant paradigm; they are not. Instead, this approach will facilitate research on problems of communication process and interaction that the dominant paradigm has struggled to study. Specifically, this article explores the question of process research in communication by reviewing three major paradigms of science and then delving more deeply into the most recent: complexity science. The article provides a broad overview of many of the major ideas in complexity science and how these ideas can be used to study many of the most difficult questions in communication science. It concludes with suggestions going forward for incorporating complexity science into communication.

Producing complex spoken numerals for time and space

NARCIS (Netherlands)

Meeuwissen, M.H.W.

2004-01-01

This thesis addressed the spoken production of complex numerals for time and space. The production of complex numerical expressions like those involved in telling time (e.g., 'quarter to four') or producing house numbers (e.g., 'two hundred forty-five') has been almost completely ignored. Yet, adult

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

Distress detection, location, and communications using advanced space technology

Science.gov (United States)

Sivertson, W. E., Jr.

1977-01-01

This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

High Efficiency Traveling-Wave Tube Power Amplifier for Ka-Band Software Defined Radio on International Space Station-A Platform for Communications Technology Development

Science.gov (United States)

Simons, Rainee N.; Force, Dale A.; Kacpura, Thomas J.

2013-01-01

The design, fabrication and RF performance of the output traveling-wave tube amplifier (TWTA) for a space based Ka-band software defined radio (SDR) is presented. The TWTA, the SDR and the supporting avionics are integrated to forms a testbed, which is currently located on an exterior truss of the International Space Station (ISS). The SDR in the testbed communicates at Ka-band frequencies through a high-gain antenna directed to NASA s Tracking and Data Relay Satellite System (TDRSS), which communicates to the ground station located at White Sands Complex. The application of the testbed is for demonstrating new waveforms and software designed to enhance data delivery from scientific spacecraft and, the waveforms and software can be upgraded and reconfigured from the ground. The construction and the salient features of the Ka-band SDR are discussed. The testbed is currently undergoing on-orbit checkout and commissioning and is expected to operate for 3 to 5 years in space.

Color-Space-Based Visual-MIMO for V2X Communication.

Science.gov (United States)

Kim, Jai-Eun; Kim, Ji-Won; Park, Youngil; Kim, Ki-Doo

2016-04-23

In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol), and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance.

Implementation of a Space Communications Cognitive Engine

Science.gov (United States)

Hackett, Timothy M.; Bilen, Sven G.; Ferreira, Paulo Victor R.; Wyglinski, Alexander M.; Reinhart, Richard C.

2017-01-01

Although communications-based cognitive engines have been proposed, very few have been implemented in a full system, especially in a space communications system. In this paper, we detail the implementation of a multi-objective reinforcement-learning algorithm and deep artificial neural networks for the use as a radio-resource-allocation controller. The modular software architecture presented encourages re-use and easy modification for trying different algorithms. Various trade studies involved with the system implementation and integration are discussed. These include the choice of software libraries that provide platform flexibility and promote reusability, choices regarding the deployment of this cognitive engine within a system architecture using the DVB-S2 standard and commercial hardware, and constraints placed on the cognitive engine caused by real-world radio constraints. The implemented radio-resource allocation-management controller was then integrated with the larger spaceground system developed by NASA Glenn Research Center (GRC).

The Complexity Of Government Communication System In Ettawa Crossbed (Ec Goat Farming In Purworejo

Directory of Open Access Journals (Sweden)

Tatag Handaka

2016-06-01

Full Text Available The study is aimed to determine the complexity of the environment that is faced by the government communication system and regulation that was used to resolve the issue. The theory used is communication system in the perspective of Niklas Luhmann. The research method used is ethnography. The population of the study are in Purworejo which becomes center of crossbreed Ettawa goat farming. Data collection technique is conducted throught interviews and observations. The results of data analysis show that the government communication system has made regulations to resolve the real problems of crossbreed Ettawa goat farming that is done by breeders. When the government communication system produces the regulation, environmental issue has grown more complex. So the regulation that was made becomes irrelevant to the demands and challenge in the crossbreed Ettawa goat farming. The government communication system is slow in reducing the complexity of the environment and producing regulation.

Communicative competences in Experimental Sciences degrees within the framework of the new European Space for Higher Education

Directory of Open Access Journals (Sweden)

Joseba Ezeiza Ramos

2009-10-01

Full Text Available The scenario for developing communicative competences in the Experimental Sciences degrees and within the new European Space for Higher Education is highly complex. This is confirmed by research reported in the White Papers on the new degrees in this subject area. Therefore, to smoothly integrate communicative and linguistic competences into future syllabi, I should first make a careful analysis of the main factors at work in the new situation. This paper seeks to provide a preliminary approach to the problem. First, I describe the academic and professional tasks that constitute the objectives of future European science degrees. This is followed by an analysis of the communicative and linguistic parameters considered essential for satisfactory attainment of these objectives. Finally, the specific skills that students must master in order to meet the demands imposed by the new framework are outlined. The results of this analysis will enable us to see how much the new situation differs from traditional university teaching. Under this new model, the development of communicative and linguistic competences will no longer be a mere adjunct to a science curriculum, but instead will become of prime importance to the academic and professional training of future scientists.

A new way to improve the robustness of complex communication networks by allocating redundancy links

International Nuclear Information System (INIS)

Shi Chunhui; Zhuo Yue; Tang Jieying; Long Keping; Peng Yunfeng

2012-01-01

We investigate the robustness of complex communication networks on allocating redundancy links. The protecting key nodes (PKN) strategy is proposed to improve the robustness of complex communication networks against intentional attack. Our numerical simulations show that allocating a few redundant links among key nodes using the PKN strategy will significantly increase the robustness of scale-free complex networks. We have also theoretically proved and demonstrated the effectiveness of the PKN strategy. We expect that our work will help achieve a better understanding of communication networks. (paper)

Forecast of space shuttle flight requirements for launch of commercial communications satellites

Science.gov (United States)

1977-01-01

The number of communication satellites required over the next 25 years to support domestic and regional communication systems for telephony, telegraphy and other low speed data; video teleconferencing, new data services, direct TV broadcasting; INTELSAT; and maritime and aeronautical services was estimated to determine the number of space shuttle flights necessary for orbital launching.

User manual of the CATSS system (version 1.0) communication analysis tool for space station

Science.gov (United States)

Tsang, C. S.; Su, Y. T.; Lindsey, W. C.

1983-01-01

The Communication Analysis Tool for the Space Station (CATSS) is a FORTRAN language software package capable of predicting the communications links performance for the Space Station (SS) communication and tracking (C & T) system. An interactive software package was currently developed to run on the DEC/VAX computers. The CATSS models and evaluates the various C & T links of the SS, which includes the modulation schemes such as Binary-Phase-Shift-Keying (BPSK), BPSK with Direct Sequence Spread Spectrum (PN/BPSK), and M-ary Frequency-Shift-Keying with Frequency Hopping (FH/MFSK). Optical Space Communication link is also included. CATSS is a C & T system engineering tool used to predict and analyze the system performance for different link environment. Identification of system weaknesses is achieved through evaluation of performance with varying system parameters. System tradeoff for different values of system parameters are made based on the performance prediction.

Measuring Early Communication in Spanish Speaking Children: The Communication Complexity Scale in Peru.

Science.gov (United States)

Atwood, Erin; Brady, Nancy C; Esplund, Amy

There is a great need in the United States to develop presymbolic evaluation tools that are widely available and accurate for individuals that come from a bilingual and/or multicultural setting. The Communication Complexity Scale (CCS) is a measure that evaluates expressive presymbolic communication including gestures, vocalizations and eye gaze. Studying the effectiveness of this tool in a Spanish speaking environment was undertaken to determine the applicability of the CCS with Spanish speaking children. Methods & Procedures: In 2011-2012, researchers from the University of Kansas and Centro Ann Sullivan del Perú (CASP) investigated communication in a cohort of 71 young Spanish speaking children with developmental disabilities and a documented history of self-injurious, stereotyped and aggressive behaviors. Communication was assessed first by parental report with translated versions of the Communication and Symbolic Behavior Scales (CSBS), a well-known assessment of early communication, and then eleven months later with the CCS. We hypothesized that the CCS and the CSBS measures would be significantly correlated in this population of Spanish speaking children. The CSBS scores from time 1 with a mean participant age of 41 months were determined to have a strong positive relationship to the CCS scores obtained at time 2 with a mean participant age of 52 months. The CCS is strongly correlated to a widely accepted measure of early communication. These findings support the validity of the Spanish version of the CCS and demonstrate its usefulness for children from another culture and for children in a Spanish speaking environment.

Low-Complexity Transmit Antenna Selection and Beamforming for Large-Scale MIMO Communications

Directory of Open Access Journals (Sweden)

Kun Qian

2014-01-01

Full Text Available Transmit antenna selection plays an important role in large-scale multiple-input multiple-output (MIMO communications, but optimal large-scale MIMO antenna selection is a technical challenge. Exhaustive search is often employed in antenna selection, but it cannot be efficiently implemented in large-scale MIMO communication systems due to its prohibitive high computation complexity. This paper proposes a low-complexity interactive multiple-parameter optimization method for joint transmit antenna selection and beamforming in large-scale MIMO communication systems. The objective is to jointly maximize the channel outrage capacity and signal-to-noise (SNR performance and minimize the mean square error in transmit antenna selection and minimum variance distortionless response (MVDR beamforming without exhaustive search. The effectiveness of all the proposed methods is verified by extensive simulation results. It is shown that the required antenna selection processing time of the proposed method does not increase along with the increase of selected antennas, but the computation complexity of conventional exhaustive search method will significantly increase when large-scale antennas are employed in the system. This is particularly useful in antenna selection for large-scale MIMO communication systems.

Color-Space-Based Visual-MIMO for V2X Communication

OpenAIRE

Jai-Eun Kim; Ji-Won Kim; Youngil Park; Ki-Doo Kim

2016-01-01

In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and w...

Complexity Perspectives on Language, Communication and Society

CERN Document Server

Bastardas-Boada, Albert

2013-01-01

The “language-communication-society” triangle defies traditional scientific approaches. Rather, it is a phenomenon that calls for an integration of complex, transdisciplinary perspectives, if we are to make any progress in understanding how it works. The highly diverse agents in play are not merely cognitive and/or cultural, but also emotional and behavioural in their specificity. Indeed, the effort may require building a theoretical and methodological body of knowledge that can effectively convey the characteristic properties of phenomena in human terms. New complexity approaches allow us to rethink our limited and mechanistic images of human societies and create more appropriate emo-cognitive dynamic and holistic models. We have to enter into dialogue with the complexity views coming out of other more ‘material’ sciences, but we also need to take steps in the linguistic and psycho-sociological fields towards creating perspectives and concepts better fitted to human characteristics. Our understanding...

Classical correlations, Bell inequalities, and communication complexity

Energy Technology Data Exchange (ETDEWEB)

Wilms, Johannes; Alber, Gernot [Institut fuer Angewandte Physik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Percival, Ian C. [Department of Physics, Univ. of London (United Kingdom)

2007-07-01

A computer program is presented which is capable of exploring generalizations of Bell-type inequalities for arbitrary numbers of classical inputs and outputs. Thereby, polytopes can be described which represent classical local realistic theories, classical theories without signaling, or classical theories with explicit signaling. These latter polytopes may also be of interest for exploring basic problems of communication complexity. As a first application the influence of non-perfect detectors is discussed in simple Bell experiments.

Deep Space Network equipment performance, reliability, and operations management information system

Science.gov (United States)

Cooper, T.; Lin, J.; Chatillon, M.

2002-01-01

The Deep Space Mission System (DSMS) Operations Program Office and the DeepSpace Network (DSN) facilities utilize the Discrepancy Reporting Management System (DRMS) to collect, process, communicate and manage data discrepancies, equipment resets, physical equipment status, and to maintain an internal Station Log. A collaborative effort development between JPL and the Canberra Deep Space Communication Complex delivered a system to support DSN Operations.

The ethics of good communication in a complex research partnership.

Science.gov (United States)

Sodeke, Stephen; Turner, Timothy; Tarver, Will

2010-08-01

The tripartite partnership among Morehouse School of Medicine, Tuskegee University, and University of Alabama at Birmingham is complex. In 2005, the three schools--with different institutional cultures, characters, and resources--agreed to collaborate in efforts to eliminate racial/ethnic disparities in cancer burdens. Pursuing this laudable aim predictably involved some miscommunication. The Bioethics Shared Resource (BSR) group foresaw such challenges and monitored interactions to prevent harm, noting that while effective communication is critical to the achievement of mutual goals, an understanding and prudent use of proven communication principles is a sine qua non for success. In this commentary, we share the undergirding moral concepts, communication approaches, and lessons learned. This experience has led us to propose an ethics of good communication for others to consider.

Modular space station, phase B extension. Information management advanced development. Volume 2: Communications terminal breadboard

Science.gov (United States)

Gerber, C. R.

1972-01-01

The design and development of the communications terminal breadboard for the modular space station are discussed. The subjects presented are: (1) history of communications terminal breadboard, (2) requirements analysis, (3) technology goals in terminal design, and (4) communications terminal board integration tests.

A Pilot Study to Teach Siblings to Support Children with Complex Communication Needs

Science.gov (United States)

Douglas, Sarah N.; Kammes, Rebecca; Nordquist, Erica; D'Agostino, Sophia

2018-01-01

Siblings play an important role in the lives of children with disabilities, especially those with complex communication needs (CCN). However, children with CCN require support to learn social and communication skills. Like other communication partners, typically developing (TD) siblings may struggle to understand how to best interact with a child…

Complex systems relationships between control, communications and computing

CERN Document Server

2016-01-01

This book gives a wide-ranging description of the many facets of complex dynamic networks and systems within an infrastructure provided by integrated control and supervision: envisioning, design, experimental exploration, and implementation. The theoretical contributions and the case studies presented can reach control goals beyond those of stabilization and output regulation or even of adaptive control. Reporting on work of the Control of Complex Systems (COSY) research program, Complex Systems follows from and expands upon an earlier collection: Control of Complex Systems by introducing novel theoretical techniques for hard-to-control networks and systems. The major common feature of all the superficially diverse contributions encompassed by this book is that of spotting and exploiting possible areas of mutual reinforcement between control, computing and communications. These help readers to achieve not only robust stable plant system operation but also properties such as collective adaptivity, integrity an...

Color-Space-Based Visual-MIMO for V2X Communication

Directory of Open Access Journals (Sweden)

Jai-Eun Kim

2016-04-01

Full Text Available In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol, and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance.

Communication complexity towards lower bounds on circuit depth

Czech Academy of Sciences Publication Activity Database

Edmonds, J.; Impagliazzo, R.; Rudich, S.; Sgall, Jiří

2001-01-01

Roč. 10, č. 3 (2001), s. 210-246 ISSN 1016-3328 R&D Projects: GA AV ČR IAA1019602; GA AV ČR IAA1019901; GA ČR GA201/97/P038; GA ČR GA201/01/1195; GA MŠk ME 103 Keywords : communication complexity%lower bounds Subject RIV: BA - General Mathematics Impact factor: 0.448, year: 2001

Communication complexity of distributed computing and a parallel algorithm for polynomial roots

International Nuclear Information System (INIS)

Tiwari, P.

1986-01-01

The first part of this thesis begins with a discussion of the minimum communication requirements in some distributed networks. The main result is a general technique for determining lower bounds on the communication complexity of problems on various distributed computer networks. This general technique is derived by simulating the general network by a linear array and then using a lower bound on the communication complexity of the problem on the linear array. Applications of this technique yield nontrivial optimal or near-optimal lower bounds on the communication complexity of distinctness, ranking, uniqueness, merging, and triangle detection on a ring, a mesh, and a complete binary tree of processors. A technique similar to the one used in proving the above results, yields interesting graph theoretic results concerning decomposition of a graph into complete bipartite subgraphs. The second part of the this is devoted to the design of a fast parallel algorithm for determining all roots of a polynomial. Given a polynomial rho(z) of degree n with m bit integer coefficients and an integer μ, the author considers the problem of determining all its roots with error less than 2/sup -μ/. It is shown that this problem is in the class NC if rho(z) has all real roots

Augmentative and Alternative Communication System (AAC) for Social Inclusion of People With Complex Communication Needs in the Industry.

Science.gov (United States)

Krüger, Simone; Berberian, Ana Paula

2015-01-01

Inclusion of people with special needs in the labor market has been increasing in some regions of Brazil as a result of the Articles 6 and 7 of the Constitution of the Federal Republic of Brazil and the Quota Law (No. 8.213/91, Art. 93) which entitle people with disabilities to work in order to improve their social condition. To support persons with complex communication needs in the workplace, 40 graphic symbols termed "symbols of industrial expressions" were developed within the framework of the COMMUNIS package. The symbols were developed for a company of the food sector in the Metropolitan Region of Curitiba, Brazil. Individual interviews were held with the human resources professionals, as well as with employees with complex communication needs in order to identify problems, assess requirements, and generate a list of specific symbols to develop. The symbols were then validated with regard to their ease of recognition. Only five symbols needed revision. The results suggest that it is possible to develop a set of symbols for the workplace that are judged to be iconic by human resources professionals and employees with complex communication needs.

Conceptualizing and communicating organizational risk dynamics in the thoroughness-efficiency space

International Nuclear Information System (INIS)

Marais, K.B.; Saleh, J.H.

2008-01-01

Organizations that design and/or operate complex systems have to make trade-offs between multiple, interacting, and sometimes conflicting goals at both the individual and organizational levels. Identifying, communicating, and resolving the conflict or tension between multiple organizational goals is challenging. Furthermore, maintaining an appropriate level of safety in such complex environments is difficult for a number of reasons discussed in this paper. The objective of this paper is to propose a set of related concepts that can help conceptualize organizational risk and help managers to understand the implications of various performance and resource pressures and make appropriate trade-offs between efficiency and thoroughness that maintain system safety. The concepts here introduced include (1) the thoroughness-efficiency space for classifying organizational behavior, and the various resource/performance and regulatory pressures that can displace organizations from one quadrant to another within this space, (2) the thoroughness-efficiency barrier and safety threshold, and (3) the efficiency penalty that organizations should accept, and not trade against organizational thoroughness, in order to maintain safety. Unfortunately, many accidents share a conceptual sameness in the way they occur. That sameness can be related to the dynamics conceptualized in this paper and the violation of the safety threshold. This sameness is the sad story of the Bhopal accident, the Piper Alpha accident, and score of others. Finally, we highlight the importance of a positive safety culture as an essential complement to regulatory pressure in maintaining safety. We illustrate the 'slippery slope of thoroughness' along which organizational behavior slides under the influence of performance pressure, and suggest that a positive safety culture can be conceived of as 'pulling this slippery slope' up and preventing the violation of the safety threshold

The content of goals in individual educational programs for students with complex communication needs.

Science.gov (United States)

Klang, Nina; Rowland, Charity; Fried-Oken, Melanie; Steiner, Sandra; Granlund, Mats; Adolfsson, Margareta

2016-01-01

The aim of the study was to explore the contents of communication-related goals in individualized education programs (IEPs) for students with complex communication needs. Goals in 43 IEPs were linked to the International Classification of Functioning, Disability and Health, Children and Youth version (ICF-CY). The results show that the communication-related IEP goals contain information on multiple domains of functioning in the ICF-CY. However, judging by the amount of codes linked to ICF-CY chapters, the IEPs contain a relatively small proportion of goals that focus on interaction with others, or participation in classroom and leisure activities. Special education teachers and speech-language pathologists working with students with complex communication needs may need support to formulate communication-related IEP goals with a focus on interaction and participation in school activities.

Symplectic geometry on moduli spaces of holomorphic bundles over complex surfaces

OpenAIRE

Khesin, Boris; Rosly, Alexei

2000-01-01

We give a comparative description of the Poisson structures on the moduli spaces of flat connections on real surfaces and holomorphic Poisson structures on the moduli spaces of holomorphic bundles on complex surfaces. The symplectic leaves of the latter are classified by restrictions of the bundles to certain divisors. This can be regarded as fixing a "complex analogue of the holonomy" of a connection along a "complex analogue of the boundary" in analogy with the real case.

Performance analysis of stationary Hadamard matrix diffusers in free-space optical communication links

Science.gov (United States)

Burrell, Derek J.; Middlebrook, Christopher T.

2017-08-01

Wireless communication systems that employ free-space optical links in place of radio/microwave technologies carry substantial benefits in terms of data throughput, network security and design efficiency. Along with these advantages comes the challenge of counteracting signal degradation caused by atmospheric turbulence in free-space environments. A fully coherent laser source experiences random phase delays along its traversing path in turbulent conditions forming a speckle pattern and lowering the received signal-to-noise ratio upon detection. Preliminary research has shown that receiver-side speckle contrast may be significantly reduced and signal-to-noise ratio increased accordingly through the use of a partially coherent light source. While dynamic diffusers and adaptive optics solutions have been proven effective, they also add expense and complexity to a system that relies on accessibility and robustness for successful implementation. A custom Hadamard diffractive matrix design is used to statically induce partial coherence in a transmitted beam to increase signal-to-noise ratio for experimental turbulence scenarios. Atmospheric phase screens are generated using an open-source software package and subsequently loaded into a spatial light modulator using nematic liquid crystals to modulate the phase.

Long-Range Intramolecular Electronic Communication in a Trinuclear Ruthenium Tropolonate Complex.

Science.gov (United States)

Yoshida, Jun; Kuwahara, Kyohei; Suzuki, Kota; Yuge, Hidetaka

2017-02-20

Dinuclear and trinuclear ruthenium complexes, [Ru(trop) 2 (C 2 trop)Ru(dppe)Cp] [2b; trop = tropolonato, C 2 trop = ethynyltropolonato, dppe = 1,2-bis(diphenylphosphino)ethane] and [Ru(trop){(C 2 trop)Ru(dppe)Cp} 2 ] (3), were synthesized, and their electronic and electrochemical properties were investigated in comparison with our previously reported complex [Ru(acac) 2 (C 2 trop)Ru(dppe)Cp] (2a). The electron-donating Ru II (dppe)Cp unit and electron-accepting Ru III O 6 unit are connected by C 2 trop in these complexes. 2a incorporates acetylacetonate as an ancillary ligand, while 2b and 3 incorporate tropolonate as an ancillary ligand. Every complex, 2a, 2b, and 3, exhibits similar UV-vis-near-IR (NIR) absorption spectra, demonstrating the lack of explicit intramolecular electronic communication between the units at least in the neutral state. The weak NIR absorption in 2a further diminished upon electrochemical oxidation, indicating almost no electronic communication between the units. In contrast, 2b and 3 exhibit broad NIR absorptions upon oxidation. Additionally, 3 exhibits four stepwise redox couples in the electrochemical study, which are formally attributed to [Ru II (trop) 3 ] - /[Ru III (trop) 3 ], two [Ru II (dppe)Cp]/[Ru III (dppe)Cp] + , and [Ru III (trop) 3 ]/[Ru IV (trop) 3 ] + couples. Clear separation of the redox couples attributed to the two terminal [Ru(dppe)Cp] units demonstrates the thermodynamic stability of the intermediate oxidation states with respect to disproportionation. Further electrochemical studies using an electrolyte including perfluorinated weakly coordinating anions and density functional theory/time-dependent density functional theory calculations confirmed the effect of ancillary ligands, acetylacetonate and tropolonate. In the case of 2a, electronic delocalization over the whole complex, especially over the [Ru(acac) 2 (trop)] unit, appears to be small. In contrast, the electronic communication between [Ru(dppe)Cp] and [Ru

Prototypes and matrix relevance learning in complex fourier space

NARCIS (Netherlands)

Straat, M.; Kaden, M.; Gay, M.; Villmann, T.; Lampe, Alexander; Seiffert, U.; Biehl, M.; Melchert, F.

2017-01-01

In this contribution, we consider the classification of time-series and similar functional data which can be represented in complex Fourier coefficient space. We apply versions of Learning Vector Quantization (LVQ) which are suitable for complex-valued data, based on the so-called Wirtinger

Min-Max Spaces and Complexity Reduction in Min-Max Expansions

Energy Technology Data Exchange (ETDEWEB)

Gaubert, Stephane, E-mail: Stephane.Gaubert@inria.fr [Ecole Polytechnique, INRIA and CMAP (France); McEneaney, William M., E-mail: wmceneaney@ucsd.edu [University of California San Diego, Dept. of Mech. and Aero. Eng. (United States)

2012-06-15

Idempotent methods have been found to be extremely helpful in the numerical solution of certain classes of nonlinear control problems. In those methods, one uses the fact that the value function lies in the space of semiconvex functions (in the case of maximizing controllers), and approximates this value using a truncated max-plus basis expansion. In some classes, the value function is actually convex, and then one specifically approximates with suprema (i.e., max-plus sums) of affine functions. Note that the space of convex functions is a max-plus linear space, or moduloid. In extending those concepts to game problems, one finds a different function space, and different algebra, to be appropriate. Here we consider functions which may be represented using infima (i.e., min-max sums) of max-plus affine functions. It is natural to refer to the class of functions so represented as the min-max linear space (or moduloid) of max-plus hypo-convex functions. We examine this space, the associated notion of duality and min-max basis expansions. In using these methods for solution of control problems, and now games, a critical step is complexity-reduction. In particular, one needs to find reduced-complexity expansions which approximate the function as well as possible. We obtain a solution to this complexity-reduction problem in the case of min-max expansions.

Improving Literacy Skills in Students with Complex Communication Needs Who Use Augmentative/Alternative Communication Systems

Science.gov (United States)

Bailey, Rita L.; Angell, Maureen E.; Stoner, Julia B.

2011-01-01

A structured intervention package including direct, scaffolded, instructional lessons was implemented using an error correction learning system and a picture book-based phonological and phonemic awareness activity for four participants with complex communication needs, ranging from 12 to 15 years, in a junior high school setting. Although…

The Referential Function of Internal Communication Groups in Complex Organizations: An Empirical Analysis.

Science.gov (United States)

Taylor, James A.; Farace, Richard V.

This paper argues that people who interact regularly and repetitively among themselves create a conjoint information space wherein common values, attitudes, and beliefs arise through the process of information transmission among the members in the space. Three major hypotheses concerning informal communication groups in organizations were tested…

Best Proximity Point Results in Complex Valued Metric Spaces

Directory of Open Access Journals (Sweden)

Binayak S. Choudhury

2014-01-01

complex valued metric spaces. We treat the problem as that of finding the global optimal solution of a fixed point equation although the exact solution does not in general exist. We also define and use the concept of P-property in such spaces. Our results are illustrated with examples.

Overlapping and permeability: Research on the pattern hierarchy of communication space and design strategy based on environmental behavior

Science.gov (United States)

Leilei, Sun; Liang, Zhang; Bing, Chen; Hong, Xi

2017-11-01

This thesis is to analyze the basic pattern hierarchy of communication space by using the theory of environmental psychology and behavior combined with relevant principles in architecture, to evaluate the design and improvement of communication space in specific meaning, and to bring new observation ideas and innovation in design methods to the system of space, environment and behavior.

Evaluation of the Communication Between Arachnoid Cysts and Neighboring Cerebrospinal Fluid Spaces by T2W 3D-SPACE With Variant Flip-Angle Technique at 3 T.

Science.gov (United States)

Algin, Oktay

2018-05-21

Phase-contrast cine magnetic resonance imaging (PC-MRI) is a widely used technique for determination of possible communication of arachnoid cysts (ACs). Three-dimensional (3D) sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE) technique is a relatively new method for 3D isotropic scanning of the entire cranium within a short time. In this research, the usage of the 3D-SPACE technique in differentiation of communicating or noncommunicating type ACs was evaluated. Thirty-five ACs in 34 patients were retrospectively examined. The 3D-SPACE, PC-MRI, and contrast material-enhanced cisternography (if present) images of the patients were analyzed. Each cyst was described according to cyst size/location, third ventricle diameter, Evans index, and presence of hydrocephalus. Communication was defined as absent (score 0), suspected (score 1), or present (score 2) on each sequence. Results of PC-MRI or cisternography (if available) examinations were used as criterion standard techniques to categorize all cysts as communicating or noncommunicating type. The results of 3D-SPACE were compared with criterion standard techniques. The comparisons between groups were performed using Mann-Whitney and Fisher exact tests. For demonstration of communication status of the cysts, criterion standard test results and 3D-SPACE findings were almost in perfect harmony (κ[95% confidence interval: 0.94]; P SPACE findings correlated with other final results at a rate of 97%. There is a positive correlation with third ventricular diameters and Evans index for all patients (r = 0.77, P SPACE technique is an easy, useful, and noninvasive alternative for the evaluation of morphology, topographical relationships, and communication status of ACs.

Integrated source and channel encoded digital communication system design study. [for space shuttles

Science.gov (United States)

Huth, G. K.

1976-01-01

The results of several studies Space Shuttle communication system are summarized. These tasks can be divided into the following categories: (1) phase multiplexing for two- and three-channel data transmission, (2) effects of phase noise on the performance of coherent communication links, (3) analysis of command system performance, (4) error correcting code tradeoffs, (5) signal detection and angular search procedure for the shuttle Ku-band communication system, and (6) false lock performance of Costas loop receivers.

Free Space Optical (FSO) Communications, Towards the Speeds of Wireline Networks

KAUST Repository

Alouini, Mohamed-Slim

2015-01-01

in the recent past, is not anymore a viable solution to fulfill the demand for more wireless applications and higher data rates. Among the many proposed solutions, optical wireless communication or free-space optical (FSO) systems have gained an increasing

A reliable, delay bounded and less complex communication protocol for multicluster FANETs

Directory of Open Access Journals (Sweden)

Wajiya Zafar

2017-02-01

Full Text Available Recently, Flying Ad-hoc Networks (FANETs, enabling ad-hoc networking between Unmanned Aerial Vehicles (UAVs is gaining importance in several military and civilian applications. The sensitivity of the applications requires adaptive; efficient; delay bounded and scalable communication network among UAVs for data transmission. Due to communication protocol complexity; rigidity; cost of commercial-off-the-shelf (COT components; limited radio bandwidth; high mobility and computational resources; maintaining the desired level of Quality of Service (QoS becomes a daunting task. For the first time in this research we propose multicluster FANETs for efficient network management; the proposed scheme considerably reduces communication cost and optimizes network performance as well as exploit low power; less complex and low cost IEEE 802.15.4 (MAC protocol for intercluster and intracluster communication. In this research both beacon enabled mode and beaconless modes have been investigated with Guaranteed Time Slots (GTS and virtual Time Division Multiple Access (TDMA respectively. The methodology plays a key role towards reserving bandwidth for latency critical applications; eliminate collisions and medium access delays. Moreover analysis ad-hoc routing protocols including two proactive (OLSR, DSDV and one reactive (AODV is also presented. The results shows that the proposed scheme guarantees high packet delivery ratios while maintaining acceptable levels of latency requirements comparable with more complex and dedicatedly designed protocols in literature.

Cooperating expert systems for space station power distribution management

International Nuclear Information System (INIS)

Nguyen, T.A.; Chiou, W.C.

1986-01-01

In a complex system such as the manned Space Station, it is deemed necessary that many expert systems must perform tasks in a concurrent and cooperative manner. An important question to arise is: what cooperative-task-performing models are appropriate for multiple expert systems to jointly perform tasks. The solution to this question will provide a crucial automation design criteria for the Space Station complex systems architecture. Based on a client/server model for performing tasks, the authors have developed a system that acts as a front-end to support loosely-coupled communications between expert systems running on multiple Symbolics machines. As an example, they use the two ART*-based expert systems to demonstrate the concept of parallel symbolic manipulation for power distribution management and dynamic load planner/scheduler in the simulated Space Station environment. This on-going work will also explore other cooperative-task-performing models as alternatives which can evaluate inter and intra expert system communication mechanisms. It will serve as a testbed and a bench-marking tool for other Space Station expert subsystem communication and information exchange

Cooperating Expert Systems For Space Station Power Distribution Management

Science.gov (United States)

Nguyen, T. A.; Chiou, W. C.

1987-02-01

In a complex system such as the manned Space Station, it is deem necessary that many expert systems must perform tasks in a concurrent and cooperative manner. An important question arise is: what cooperative-task-performing models are appropriate for multiple expert systems to jointly perform tasks. The solution to this question will provide a crucial automation design criteria for the Space Station complex systems architecture. Based on a client/server model for performing tasks, we have developed a system that acts as a front-end to support loosely-coupled communications between expert systems running on multiple Symbolics machines. As an example, we use two ART*-based expert systems to demonstrate the concept of parallel symbolic manipulation for power distribution management and dynamic load planner/scheduler in the simulated Space Station environment. This on-going work will also explore other cooperative-task-performing models as alternatives which can evaluate inter and intra expert system communication mechanisms. It will be served as a testbed and a bench-marking tool for other Space Station expert subsystem communication and information exchange.

'Complexity' and anomalous transport in space plasmas

International Nuclear Information System (INIS)

Chang, Tom; Wu Chengchin

2002-01-01

'Complexity' has become a hot topic in nearly every field of modern physics. Space plasma is of no exception. In this paper, it is demonstrated that the sporadic and localized interactions of magnetic coherent structures are the origin of 'complexity' in space plasmas. The intermittent localized interactions, which generate the anomalous diffusion, transport, and evolution of the macroscopic state variables of the overall dynamical system, may be modeled by a triggered (fast) localized chaotic growth equation of a set of relevant order parameters. Such processes would generally pave the way for the global system to evolve into a 'complex' state of long-ranged interactions of fluctuations, displaying the phenomenon of forced and/or self-organized criticality. An example of such type of anomalous transport and evolution in a sheared magnetic field is provided via two-dimensional magnetohydrodynamic simulations. The coarse-grained dissipation due to the intermittent triggered interactions among the magnetic coherent structures induces a 'fluctuation-induced nonlinear instability' that reconfigures the sheared magnetic field into an X-point magnetic geometry (in the mean field sense), leading to the anomalous acceleration of the magnetic coherent structures. A phenomenon akin to such type of anomalous transport and acceleration, the so-called bursty bulk flows, has been commonly observed in the plasma sheet of the Earth's magnetotail

Information communication on complex networks

International Nuclear Information System (INIS)

Igarashi, Akito; Kawamoto, Hiroki; Maruyama, Takahiro; Morioka, Atsushi; Naganuma, Yuki

2013-01-01

Since communication networks such as the Internet, which is regarded as a complex network, have recently become a huge scale and a lot of data pass through them, the improvement of packet routing strategies for transport is one of the most significant themes in the study of computer networks. It is especially important to find routing strategies which can bear as many traffic as possible without congestion in complex networks. First, using neural networks, we introduce a strategy for packet routing on complex networks, where path lengths and queue lengths in nodes are taken into account within a framework of statistical physics. Secondly, instead of using shortest paths, we propose efficient paths which avoid hubs, nodes with a great many degrees, on scale-free networks with a weight of each node. We improve the heuristic algorithm proposed by Danila et. al. which optimizes step by step routing properties on congestion by using the information of betweenness, the probability of paths passing through a node in all optimal paths which are defined according to a rule, and mitigates the congestion. We confirm the new heuristic algorithm which balances traffic on networks by achieving minimization of the maximum betweenness in much smaller number of iteration steps. Finally, We model virus spreading and data transfer on peer-to-peer (P2P) networks. Using mean-field approximation, we obtain an analytical formulation and emulate virus spreading on the network and compare the results with those of simulation. Moreover, we investigate the mitigation of information traffic congestion in the P2P networks.

Challenges for deep space communications in the 1990s

Science.gov (United States)

Dumas, Larry N.; Hornstein, Robert M.

1991-01-01

The discussion of NASA's Deep Space Network (DSN) examines the evolving character of aerospace missions and the corresponding changes in the DSN architecture. Deep space missions are reviewed, and it is noted that the two 34-m and the 70-m antenna subnets of the DSN are heavily loaded and more use is expected. High operational workload and the challenge of network cross-support are the design drivers for a flexible DSN architecture configuration. Incorporated in the design are antenna arraying for aperture augmentation, beam-waveguide antennas for frequency agility, and connectivity with non-DSN sites for cross-support. Compatibility between spacecraft and ground-facility designs is important for establishing common international standards of communication and data-system specification.

Quantum correlations in Newtonian space and time: arbitrarily fast communication or nonlocality

Science.gov (United States)

Gisin, Nicolas

2013-03-01

Experimental violations of Bell inequalities using space-like separated measurements precludes the explanation of quantum correlations through causal influences propagating at subluminal speed. Yet, ``everything looks as if the two parties somehow communicate behind the scene.'' We investigate the assumption that they do so at a speed faster than light, though finite. Such an assumption doesn't respect the spirit of Einstein relativity. However, it is not crystal clear that such ``communication behind the scene'' would contradict relativity. Indeed, one could imagine that this communication remains for ever hidden to humans, i.e. that it could not be controlled by humans, only Nature exploits it to produce correlations that can't be explained by usual common causes. To define faster than light hidden communication requires a universal privileged reference frame in which this faster than light speed is defined. Again, such a universal privileged frame is not in the spirit of relativity, but it is also clearly not in contradiction: for example the reference frame in which the cosmic microwave background radiation is isotropic defines such a privileged frame. Hence, a priori, a hidden communication explanation is not more surprising than nonlocality. We prove that for any finite speed, such models predict correlations that can be exploited for faster-than-light communication. This superluminal communication doesn't require access to any hidden physical quantities, but only the manipulation of measurement devices at the level of our present-day description of quantum experiments. Consequently, all possible explanations of quantum correlations that satisfy the principle of continuity, which states that everything propagates gradually and continuously through space and time, or in other words, all combination of local common causes and direct causes that reproduce quantum correlations, lead to faster than light communication. Accordingly, either there is superluminal

Research on the method of measuring space information network capacity in communication service

Directory of Open Access Journals (Sweden)

Zhu Shichao

2017-02-01

Full Text Available Because of the large scale characteristic of space information network in terms of space and time and the increasing of its complexity,existing measuring methods of information transmission capacity have been unable to measure the existing and future space information networkeffectively.In this study,we firstly established a complex model of space information network,and measured the whole space information network capacity by means of analyzing data access capability to the network and data transmission capability within the network.At last,we verified the rationality of the proposed measuring method by using STK and Matlab simulation software for collaborative simulation.

Monolithic microwave integrated circuit technology for advanced space communication

Science.gov (United States)

Ponchak, George E.; Romanofsky, Robert R.

1988-01-01

Future Space Communications subsystems will utilize GaAs Monolithic Microwave Integrated Circuits (MMIC's) to reduce volume, weight, and cost and to enhance system reliability. Recent advances in GaAs MMIC technology have led to high-performance devices which show promise for insertion into these next generation systems. The status and development of a number of these devices operating from Ku through Ka band will be discussed along with anticipated potential applications.

Applications of Microwave Photonics in Radio Astronomy and Space Communication

Science.gov (United States)

D'Addario, Larry R.; Shillue, William P.

2006-01-01

An overview of narrow band vs wide band signals is given. Topics discussed included signal transmission, reference distribution and photonic antenna metrology. Examples of VLA, ALMA, ATA and DSN arrays are given. . Arrays of small antennas have become more cost-effective than large antennas for achieving large total aperture or gain, both for astronomy and for communication. It is concluded that emerging applications involving arrays of many antennas require low-cost optical communication of both wide bandwidth and narrow bandwidth; development of round-trip correction schemes enables timing precision; and free-space laser beams with microwave modulation allow structural metrology with approx 100 micrometer precision over distances of 200 meters.

Essential Biodiversity Variables: A framework for communication between the biodiversity community and space agencies

Science.gov (United States)

Leidner, A. K.; Skidmore, A. K.; Turner, W. W.; Geller, G. N.

2017-12-01

The biodiversity community is working towards developing a consensus on a set of Essential Biodiversity Variables (EBVs) that can be used to measure and monitor biodiversity change over time. These EBVs will inform research, modeling, policy, and assessment efforts. The synoptic coverage provided by satellite data make remote sensing a particularly important observation tool to inform many EBVs. Biodiversity is a relatively new subject matter for space agencies, and thus the definition, description, and requirements of EBVs with a significant remote sensing component can foster ways for the biodiversity community to clearly and concisely communicate observational needs to space agencies and the Committee on Earth Observing Satellites (CEOS, the international coordinating body for civilian space agencies). Here, we present an overview of EBVs with a particular emphasis on those for which remote sensing will play a significant role and also report on the results of recent workshops to prioritize and refine EBVs. Our goal is to provide a framework for the biodiversity community to coalesce around a set of observational needs to convey to space agencies. Compared to many physical science disciplines, the biodiversity community represents a wide range of sub-disciplines and organizations (academia, non-governmental organizations, research institutes, national and local natural resource management agencies, etc.), which creates additional challenges when communicating needs to space agencies unfamiliar with the topic. EBVs thus offer a communication pathway that could increase awareness within space agencies of the uses of remote sensing for biodiversity research and applications, which in turn could foster greater use of remote sensing in the broader biodiversity community.

Transforming communicative spaces: the rhythm of gender in meetings in rural Solomon Islands

Directory of Open Access Journals (Sweden)

Michelle Dyer

2018-03-01

Full Text Available Women's lack of participation in important decision making is noted as an obstacle to sustainable development in many parts of the world. An initial issue for gender equity in environmental decision making in many developing country contexts is not only women's inclusion but also their substantive participation in decision-making forums. In this article I examine the power structures embedded in the public communicative spaces in a village in the Western Province of Solomon Islands using empirical data in conjunction with ethnographic understanding of gendered meeting styles. The data reveal some reasons why women may be silenced as public political actors. It also raises the potential for development actors to create conceptual space for specific women's ways of meeting and validating women's meeting styles. These findings have implications for encouraging transformative communicative spaces and formats that allow transcendence of socially embedded power structures.

Performance of Cat's Eye Modulating Retro-Reflectors for Free-Space Optical Communications

National Research Council Canada - National Science Library

Rabinovich, W. S; Goetz, P. G; Mahon, R; Swingen, L; Murphy, J; Gilbreath, G. C; Binari, S; Waluschka, E

2004-01-01

Modulating retro-reflectors (MRR) couple passive optical retro-reflectors with electro-optic modulators to allow free-space optical communication with a laser and pointing/acquisition/tracking system required on only one end of the link...

[Oral communication: short history and some rules].

Science.gov (United States)

Panini, Roberta; Fiorini, Fulvio

2015-01-01

The verbal communication represents the first human communication, that even more used and one most immediate. History and the development of communication is divided into historical periods, is complex and is bound to the period contingencies and to the social reference community. The oral communication is never isolated but is always taken by the not verbal one, including the silences, the position and the spaces (c.d. proxemics). The good communicator stimulates the cooperation through the conversation rule respect (qualities, amounts, way and relation) and reduces the possible asymmetry between broadcaster and receiver fitting its code to that of the interlocutor.

Spectral space-time coding for optical communications through a multimode fiber

NARCIS (Netherlands)

Alonso, A.; Berghmans, F.; Thienpont, H.; Danckaert, J.; Desmet, L.

2001-01-01

We propose a method for coding the mode structure of a multimode optical fiber by spectral coding mixed with space-time modulation. With this system we can improve the data carrying capacity of a multimode fiber for optical communications and optical interconnects, and encode and decode the

Intensity position modulation for free-space laser communication system

Science.gov (United States)

Jangjoo, Alireza; Faghihi, F.

2004-12-01

In this research a novel modulation technique for free-space laser communication system called Intensity Position Modulation (IPM) is carried out. According to TEM00 mode of a laser beam and by linear fitting on the Gaussian function as an approximation, the variation of linear part on the reverse biased pn photodiode produced alternating currents which contain the information. Here, no characteristic property of the beam as intensity or frequency is changed and only the beam position moves laterally. We demonstrated that in this method no bandwidth is required, so it is possible to reduce the background radiation noise by narrowband filtering of the carrier. The fidelity of the analog voice communication system which is made upon the IPM is satisfactory and we are able to transmit the audio signals up to 1Km.

Color-Space-Based Visual-MIMO for V2X Communication †

Science.gov (United States)

Kim, Jai-Eun; Kim, Ji-Won; Park, Youngil; Kim, Ki-Doo

2016-01-01

In this paper, we analyze the applicability of color-space-based, color-independent visual-MIMO for V2X. We aim to achieve a visual-MIMO scheme that can maintain the original color and brightness while performing seamless communication. We consider two scenarios of GCM based visual-MIMO for V2X. One is a multipath transmission using visual-MIMO networking and the other is multi-node V2X communication. In the scenario of multipath transmission, we analyze the channel capacity numerically and we illustrate the significance of networking information such as distance, reference color (symbol), and multiplexing-diversity mode transitions. In addition, in the V2X scenario of multiple access, we may achieve the simultaneous multiple access communication without node interferences by dividing the communication area using image processing. Finally, through numerical simulation, we show the superior SER performance of the visual-MIMO scheme compared with LED-PD communication and show the numerical result of the GCM based visual-MIMO channel capacity versus distance. PMID:27120603

The application of visual communication design in display design

Institute of Scientific and Technical Information of China (English)

仪晓华

2015-01-01

Visual communication design is a kind of visual language and the art of communication behavior, it condenses complex and chaos and obscure information can in the shortest possible time to be understanding of the functional information, at the same time, make the design work itself sound art, philosophy and culture, cause the audience’s perception experience and emotional resonance, and eventually approved. Display of visual communication don’t like people use language to convey, but in all kinds of display environment by graphics, text, color elements such as passing information to people, visual communication design as a medium between designer and audience, communicate through planar graphic elements, format design, the combination of the text elements, color elements make exhibition has rhythm beauty so as to build a display space, the space information accurate, vivid and clear function division, comfortable, and the outline of rich imagination space to the person and strong visual impression.

Video semaphore decoding for free-space optical communication

Science.gov (United States)

Last, Matthew; Fisher, Brian; Ezekwe, Chinwuba; Hubert, Sean M.; Patel, Sheetal; Hollar, Seth; Leibowitz, Brian S.; Pister, Kristofer S. J.

2001-04-01

Using teal-time image processing we have demonstrated a low bit-rate free-space optical communication system at a range of more than 20km with an average optical transmission power of less than 2mW. The transmitter is an autonomous one cubic inch microprocessor-controlled sensor node with a laser diode output. The receiver is a standard CCD camera with a 1-inch aperture lens, and both hardware and software implementations of the video semaphore decoding algorithm. With this system sensor data can be reliably transmitted 21 km form San Francisco to Berkeley.

On the performance of free-space optical communication systems with multiuser diversity

KAUST Repository

Yang, Liang; Gao, Xiqi; Alouini, Mohamed-Slim

2014-01-01

Free space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short range applications. To address this, we propose a multiuser diversity (MD

Communications Relay and Human-Assisted Sample Return from the Deep Space Gateway

Science.gov (United States)

Cichan, T.; Hopkins, J. B.; Bierhaus, B.; Murrow, D. W.

2018-02-01

The Deep Space Gateway can enable or enhance exploration of the lunar surface through two capabilities: 1. communications relay, opening up access to the lunar farside, and 2. sample return, enhancing the ability to return large sample masses.

Discovery deep space optical communications (DSOC) transceiver

Science.gov (United States)

Roberts, W. Thomas

2017-02-01

NASA's 22 cm diameter Deep Space Optical Communications (DSOC) Transceiver is designed to provide a bidirectional optical link between a spacecraft in the inner solar system and an Earth-based optical ground station. This design, optimized for operation across a wide range of illumination conditions, is focused on minimizing blinding from stray light, and providing reliable, accurate attitude information to point its narrow communication beam accurately to the future location of the ground terminal. Though our transceiver will transmit in the 1550 nm waveband and receive in the 1064 nm waveband, the system design relies heavily on reflective optical elements, extending flexibility to be modified for use at different wavebands. The design makes use of common path propagation among transmit, receive and pointing verification optical channels to maintain precise alignment among its components, and to naturally correct for element misalignment resulting from launch or thermal element perturbations. This paper presents the results of trade studies showing the evolution of the design, unique operational characteristics of the design, elements that help to maintain minimal stray light contamination, and preliminary results from development and initial testing of a functional aluminum test model.

Multi-aperture digital coherent combining for free-space optical communication receivers.

Science.gov (United States)

Geisler, David J; Yarnall, Timothy M; Stevens, Mark L; Schieler, Curt M; Robinson, Bryan S; Hamilton, Scott A

2016-06-13

Space-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity. This is accomplished via coherent detection behind each aperture followed by digitization. The digitized signals are then combined in a digital signal processing chain. Experimental results demonstrate lossless coherent combining of four lasercom signals, at power levels below 0.1 photons/bit/aperture.

Entangled photons and quantum communication

Energy Technology Data Exchange (ETDEWEB)

Yuan Zhensheng, E-mail: yuanzs@ustc.edu.c [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, 69120 Heidelberg (Germany); Bao Xiaohui [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, 69120 Heidelberg (Germany); Lu Chaoyang; Zhang Jun; Peng Chengzhi [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Pan Jianwei, E-mail: pan@ustc.edu.c [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Physikalisches Institut, Universitaet Heidelberg, Philosophenweg 12, 69120 Heidelberg (Germany)

2010-12-15

This article reviews the progress of quantum communication that utilizes photonic entanglement. We start with a survey of various methods for generating entangled photons, followed by an introduction of the theoretical principles and the experimental implementations of quantum key distribution. We then move on to a discussion of more involved quantum communication protocols including quantum dense coding, teleportation and quantum communication complexity. After that, we review the progress in free-space quantum communication, decoherence-free subspace, and quantum repeater protocols which are essential ingredients for long-distance quantum communication. Practical realizations of quantum repeaters, which require an interface between photons and quantum memories, are discussed briefly. Finally, we draw concluding remarks considering the technical challenges, and put forward an outlook on further developments of this field.

Entangled photons and quantum communication

International Nuclear Information System (INIS)

Yuan Zhensheng; Bao Xiaohui; Lu Chaoyang; Zhang Jun; Peng Chengzhi; Pan Jianwei

2010-01-01

This article reviews the progress of quantum communication that utilizes photonic entanglement. We start with a survey of various methods for generating entangled photons, followed by an introduction of the theoretical principles and the experimental implementations of quantum key distribution. We then move on to a discussion of more involved quantum communication protocols including quantum dense coding, teleportation and quantum communication complexity. After that, we review the progress in free-space quantum communication, decoherence-free subspace, and quantum repeater protocols which are essential ingredients for long-distance quantum communication. Practical realizations of quantum repeaters, which require an interface between photons and quantum memories, are discussed briefly. Finally, we draw concluding remarks considering the technical challenges, and put forward an outlook on further developments of this field.

Analysis of large optical ground stations for deep-space optical communications

Science.gov (United States)

Garcia-Talavera, M. Reyes; Rivera, C.; Murga, G.; Montilla, I.; Alonso, A.

2017-11-01

Inter-satellite and ground to satellite optical communications have been successfully demonstrated over more than a decade with several experiments, the most recent being NASA's lunar mission Lunar Atmospheric Dust Environment Explorer (LADEE). The technology is in a mature stage that allows to consider optical communications as a high-capacity solution for future deep-space communications [1][2], where there is an increasing demand on downlink data rate to improve science return. To serve these deep-space missions, suitable optical ground stations (OGS) have to be developed providing large collecting areas. The design of such OGSs must face both technical and cost constraints in order to achieve an optimum implementation. To that end, different approaches have already been proposed and analyzed, namely, a large telescope based on a segmented primary mirror, telescope arrays, and even the combination of RF and optical receivers in modified versions of existing Deep-Space Network (DSN) antennas [3][4][5]. Array architectures have been proposed to relax some requirements, acting as one of the key drivers of the present study. The advantages offered by the array approach are attained at the expense of adding subsystems. Critical issues identified for each implementation include their inherent efficiency and losses, as well as its performance under high-background conditions, and the acquisition, pointing, tracking, and synchronization capabilities. It is worth noticing that, due to the photon-counting nature of detection, the system performance is not solely given by the signal-to-noise ratio parameter. To start with the analysis, first the main implications of the deep space scenarios are summarized, since they are the driving requirements to establish the technical specifications for the large OGS. Next, both the main characteristics of the OGS and the potential configuration approaches are presented, getting deeper in key subsystems with strong impact in the

High-dimensional structured light coding/decoding for free-space optical communications free of obstructions.

Science.gov (United States)

Du, Jing; Wang, Jian

2015-11-01

Bessel beams carrying orbital angular momentum (OAM) with helical phase fronts exp(ilφ)(l=0;±1;±2;…), where φ is the azimuthal angle and l corresponds to the topological number, are orthogonal with each other. This feature of Bessel beams provides a new dimension to code/decode data information on the OAM state of light, and the theoretical infinity of topological number enables possible high-dimensional structured light coding/decoding for free-space optical communications. Moreover, Bessel beams are nondiffracting beams having the ability to recover by themselves in the face of obstructions, which is important for free-space optical communications relying on line-of-sight operation. By utilizing the OAM and nondiffracting characteristics of Bessel beams, we experimentally demonstrate 12 m distance obstruction-free optical m-ary coding/decoding using visible Bessel beams in a free-space optical communication system. We also study the bit error rate (BER) performance of hexadecimal and 32-ary coding/decoding based on Bessel beams with different topological numbers. After receiving 500 symbols at the receiver side, a zero BER of hexadecimal coding/decoding is observed when the obstruction is placed along the propagation path of light.

Quantum theory in real Hilbert space: How the complex Hilbert space structure emerges from Poincaré symmetry

Science.gov (United States)

Moretti, Valter; Oppio, Marco

As earlier conjectured by several authors and much later established by Solèr (relying on partial results by Piron, Maeda-Maeda and other authors), from the lattice theory point of view, Quantum Mechanics may be formulated in real, complex or quaternionic Hilbert spaces only. Stückelberg provided some physical, but not mathematically rigorous, reasons for ruling out the real Hilbert space formulation, assuming that any formulation should encompass a statement of Heisenberg principle. Focusing on this issue from another — in our opinion, deeper — viewpoint, we argue that there is a general fundamental reason why elementary quantum systems are not described in real Hilbert spaces. It is their basic symmetry group. In the first part of the paper, we consider an elementary relativistic system within Wigner’s approach defined as a locally-faithful irreducible strongly-continuous unitary representation of the Poincaré group in a real Hilbert space. We prove that, if the squared-mass operator is non-negative, the system admits a natural, Poincaré invariant and unique up to sign, complex structure which commutes with the whole algebra of observables generated by the representation itself. This complex structure leads to a physically equivalent reformulation of the theory in a complex Hilbert space. Within this complex formulation, differently from what happens in the real one, all selfadjoint operators represent observables in accordance with Solèr’s thesis, and the standard quantum version of Noether theorem may be formulated. In the second part of this work, we focus on the physical hypotheses adopted to define a quantum elementary relativistic system relaxing them on the one hand, and making our model physically more general on the other hand. We use a physically more accurate notion of irreducibility regarding the algebra of observables only, we describe the symmetries in terms of automorphisms of the restricted lattice of elementary propositions of the

A Very Large Area Network (VLAN) knowledge-base applied to space communication problems

Science.gov (United States)

Zander, Carol S.

1988-01-01

This paper first describes a hierarchical model for very large area networks (VLAN). Space communication problems whose solution could profit by the model are discussed and then an enhanced version of this model incorporating the knowledge needed for the missile detection-destruction problem is presented. A satellite network or VLAN is a network which includes at least one satellite. Due to the complexity, a compromise between fully centralized and fully distributed network management has been adopted. Network nodes are assigned to a physically localized group, called a partition. Partitions consist of groups of cell nodes with one cell node acting as the organizer or master, called the Group Master (GM). Coordinating the group masters is a Partition Master (PM). Knowledge is also distributed hierarchically existing in at least two nodes. Each satellite node has a back-up earth node. Knowledge must be distributed in such a way so as to minimize information loss when a node fails. Thus the model is hierarchical both physically and informationally.

Interfacing Space Communications and Navigation Network Simulation with Distributed System Integration Laboratories (DSIL)

Science.gov (United States)

Jennings, Esther H.; Nguyen, Sam P.; Wang, Shin-Ywan; Woo, Simon S.

2008-01-01

NASA's planned Lunar missions will involve multiple NASA centers where each participating center has a specific role and specialization. In this vision, the Constellation program (CxP)'s Distributed System Integration Laboratories (DSIL) architecture consist of multiple System Integration Labs (SILs), with simulators, emulators, testlabs and control centers interacting with each other over a broadband network to perform test and verification for mission scenarios. To support the end-to-end simulation and emulation effort of NASA' exploration initiatives, different NASA centers are interconnected to participate in distributed simulations. Currently, DSIL has interconnections among the following NASA centers: Johnson Space Center (JSC), Kennedy Space Center (KSC), Marshall Space Flight Center (MSFC) and Jet Propulsion Laboratory (JPL). Through interconnections and interactions among different NASA centers, critical resources and data can be shared, while independent simulations can be performed simultaneously at different NASA locations, to effectively utilize the simulation and emulation capabilities at each center. Furthermore, the development of DSIL can maximally leverage the existing project simulation and testing plans. In this work, we describe the specific role and development activities at JPL for Space Communications and Navigation Network (SCaN) simulator using the Multi-mission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE) tool to simulate communications effects among mission assets. Using MACHETE, different space network configurations among spacecrafts and ground systems of various parameter sets can be simulated. Data that is necessary for tracking, navigation, and guidance of spacecrafts such as Crew Exploration Vehicle (CEV), Crew Launch Vehicle (CLV), and Lunar Relay Satellite (LRS) and orbit calculation data are disseminated to different NASA centers and updated periodically using the High Level Architecture (HLA). In

Quantum communications

CERN Document Server

Cariolaro, Gianfranco

2015-01-01

This book demonstrates that a quantum communication system using the coherent light of a laser can achieve performance orders of magnitude superior to classical optical communications Quantum Communications provides the Masters and PhD signals or communications student with a complete basics-to-applications course in using the principles of quantum mechanics to provide cutting-edge telecommunications. Assuming only knowledge of elementary probability, complex analysis and optics, the book guides its reader through the fundamentals of vector and Hilbert spaces and the necessary quantum-mechanical ideas, simply formulated in four postulates. A turn to practical matters begins with and is then developed by: ·         development of the concept of quantum decision, emphasizing the optimization of measurements to extract useful information from a quantum system; ·         general formulation of a transmitter–receiver system ·         particular treatment of the most popular quantum co...

Temporal characteristic analysis of laser-modulated pulsed X-ray source for space X-ray communication

Science.gov (United States)

Hang, Shuang; Liu, Yunpeng; Li, Huan; Tang, Xiaobin; Chen, Da

2018-04-01

X-ray communication (XCOM) is a new communication type and is expected to realize high-speed data transmission in some special communication scenarios, such as deep space communication and blackout communication. This study proposes a high-speed modulated X-ray source scheme based on the laser-to-X-ray conversion. The temporal characteristics of the essential components of the proposed laser-modulated pulsed X-ray source (LMPXS) were analyzed to evaluate its pulse emission performance. Results show that the LMPXS can provide a maximum modulation rate up to 100 Mbps which is expected to significantly improve the data rate of XCOM.

Space station communications and tracking equipment management/control system

Science.gov (United States)

Kapell, M. H.; Seyl, J. W.

1982-01-01

Design details of a communications and tracking (C and T) local area network and the distribution system requirements for the prospective space station are described. The hardware will be constructed of LRUs, including those for baseband, RF, and antenna subsystems. It is noted that the C and T equipment must be routed throughout the station to accommodate growth of the station. Configurations of the C and T modules will therefore be dependent on the function of the space station module where they are located. A block diagram is provided of a sample C and T hardware distribution configuration. A topology and protocol will be needed to accommodate new terminals, wide bandwidths, bidirectional message transmission, and distributed functioning. Consideration will be given to collisions occurring in the data transmission channels.

Double complexes and cohomological hierarchy in a space of weakly invariant Lagrangians of mechanics

International Nuclear Information System (INIS)

Khudaverdyan, O.M.; Saakyan, D.A.

1998-01-01

For a given configuration space M and Lie algebra G acting on M the space ν 0.0 of weakly G-invariant Lagrangians, i.e., Lagrangians whose motion equations left-hand sides are G-invariant, is studied. The problem is reformulated in terms of the double complex of Lie algebra cochains with values in the complex of Lagrangians. Calculating the cohomology of this complex by the method of spectral sequences we arrive at the hierarchy in the space ν 0.0 . The double filtration {ν s.σ }, s = 0,1,2,3,4, σ = 0,1, and the homomorphisms on every space ν s,σ are constructed. These homomorphisms take values in the cohomologies of the algebra G and the configuration space M. On one hand, every space ν s,σ in the kernel of the corresponding homomorphism, while the space itself is defined by its physical properties

Influence of wind speed on free space optical communication performance for Gaussian beam propagation through non Kolmogorov strong turbulence

International Nuclear Information System (INIS)

Deng Peng; Yuan Xiuhua; Zeng Yanan; Zhao Ming; Luo Hanjun

2011-01-01

In free-space optical communication links, atmospheric turbulence causes fluctuations in both the intensity and the phase of the received signal, affecting link performance. Most theoretical treatments have been described by Kolmogorov's power spectral density model through weak turbulence with constant wind speed. However, several experiments showed that Kolmogorov theory is sometimes incomplete to describe atmospheric turbulence properly, especially through the strong turbulence with variable wind speed, which is known to contribute significantly to the turbulence in the atmosphere. We present an optical turbulence model that incorporates into variable wind speed instead of constant value, a non-Kolmogorov power spectrum that uses a generalized exponent instead of constant standard exponent value 11/3, and a generalized amplitude factor instead of constant value 0.033. The free space optical communication performance for a Gaussian beam wave of scintillation index, mean signal-to-noise ratio , and mean bit error rate , have been derived by extended Rytov theory in non-Kolmogorov strong turbulence. And then the influence of wind speed variations on free space optical communication performance has been analyzed under different atmospheric turbulence intensities. The results suggest that the effects of wind speed variation through non-Kolmogorov turbulence on communication performance are more severe in many situations and need to be taken into account in free space optical communication. It is anticipated that this work is helpful to the investigations of free space optical communication performance considering wind speed under severe weather condition in the strong atmospheric turbulence.

Communication Complexity

Indian Academy of Sciences (India)

Jaikumar Radhakrishnan

We allow a small probability of error. Goal: minimize the total number of bits transmitted. ... using tools from combinatorics, coding theory, algebra, analysis, etc. Jaikumar Radhakrishnan. Communication .... Assume Alice and Bob know a good error correcting code. E : {0, 1}n → {0, 1}10n with distance, say, 3n. Alice.

Major technological innovations introduced in the large antennas of the Deep Space Network

Science.gov (United States)

Imbriale, W. A.

2002-01-01

The NASA Deep Space Network (DSN) is the largest and most sensitive scientific, telecommunications and radio navigation network in the world. Its principal responsibilities are to provide communications, tracking, and science services to most of the world's spacecraft that travel beyond low Earth orbit. The network consists of three Deep Space Communications Complexes. Each of the three complexes consists of multiple large antennas equipped with ultra sensitive receiving systems. A centralized Signal Processing Center (SPC) remotely controls the antennas, generates and transmits spacecraft commands, and receives and processes the spacecraft telemetry.

What is the public's role in 'space' policymaking? Images of the public by practitioners of 'space' communication in the United Kingdom.

Science.gov (United States)

Entradas, Marta

2016-07-01

Studies on experts' understanding of the public have mainly focused on the views of scientists. We add to the literature on constructions of the public by analyzing the views of decision-makers, professional science communicators and scientists involved in 'space' communication on the public and public participation in policy. Findings show that contextual situations and roles determine the way the public is conceptualised: the public is sophisticated and knowledgeable to participate in space activities/citizen science, but in matters of policy, a gullible image of the public is brought up. Despite the democratic talk on participation, practitioners delimited public involvement in policy in some way or other to protect their own power and decision-making capabilities. This conception of the public competes with the stated aims of scientific and political institutions for public engagement and the substantive value of public participation, leaving a limited role for the public in space policymaking. © The Author(s) 2015.

Multi-Objective Reinforcement Learning-Based Deep Neural Networks for Cognitive Space Communications

Science.gov (United States)

Ferreria, Paulo Victor R.; Paffenroth, Randy; Wyglinski, Alexander M.; Hackett, Timothy M.; Bilen, Sven G.; Reinhart, Richard C.; Mortensen, Dale J.

2017-01-01

Future communication subsystems of space exploration missions can potentially benefit from software-defined radios (SDRs) controlled by machine learning algorithms. In this paper, we propose a novel hybrid radio resource allocation management control algorithm that integrates multi-objective reinforcement learning and deep artificial neural networks. The objective is to efficiently manage communications system resources by monitoring performance functions with common dependent variables that result in conflicting goals. The uncertainty in the performance of thousands of different possible combinations of radio parameters makes the trade-off between exploration and exploitation in reinforcement learning (RL) much more challenging for future critical space-based missions. Thus, the system should spend as little time as possible on exploring actions, and whenever it explores an action, it should perform at acceptable levels most of the time. The proposed approach enables on-line learning by interactions with the environment and restricts poor resource allocation performance through virtual environment exploration. Improvements in the multiobjective performance can be achieved via transmitter parameter adaptation on a packet-basis, with poorly predicted performance promptly resulting in rejected decisions. Simulations presented in this work considered the DVB-S2 standard adaptive transmitter parameters and additional ones expected to be present in future adaptive radio systems. Performance results are provided by analysis of the proposed hybrid algorithm when operating across a satellite communication channel from Earth to GEO orbit during clear sky conditions. The proposed approach constitutes part of the core cognitive engine proof-of-concept to be delivered to the NASA Glenn Research Center SCaN Testbed located onboard the International Space Station.

The complex structures on the coadjoint orbit spaces of Diff(S1) and on Bers' universal Teichmueller space are compatible

International Nuclear Information System (INIS)

Nag, S.; Verjovsky, A.

1988-08-01

Precisely two coadjoint orbit spaces of the group of string reparametrizations carry in a natural way the structure of infinite dimensional, holomorphically homogeneous complex manifolds. These are M 1 =Diff(S 1 )/Rot(S 1 ) and M 2 =Diff(S 1 )/Mo-barb(S 1 ). M 2 can be naturally considered as (embedded in) the classical univeral Teichmueller space T(Δ), simply by noting that a diffeomorphism of S 1 is a quasi-symmetric homeomorphism. T(Δ) is itself a homomorphically homogeneous complex Banach manifold. We prove that the inclusion of M 2 in T(Δ) is complex analytic. Every Teichmueller space of finite or infinite dimension is contained canonically and holomorphically in T(Δ). Our result thus appears to connect the loop space approach to bosonic string theory with the sum-over moduli (Polyakov path integral) approach. (author). 12 refs

Visible laser and superluminescent diode based free space and underwater communications

KAUST Repository

Ooi, Boon S.

2017-01-30

We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

Visible laser and superluminescent diode based free space and underwater communications

KAUST Repository

Ooi, Boon S.

2017-01-01

We report on our recent progress in high-modulation-efficiency, InGaN-based integrated waveguide modulator-laser diodes (IWM-LDs), high-speed violet and blue emitting superluminescent diodes (SLDs), InGaN-based vertical-cavity surface-emitting lasers (VCSELs), and their applications for gigahertz laser based free-space and underwater wireless optical communications.

Vector bundles on complex projective spaces

CERN Document Server

Okonek, Christian; Spindler, Heinz

1980-01-01

This expository treatment is based on a survey given by one of the authors at the Séminaire Bourbaki in November 1978 and on a subsequent course held at the University of Göttingen. It is intended to serve as an introduction to the topical question of classification of holomorphic vector bundles on complex projective spaces, and can easily be read by students with a basic knowledge of analytic or algebraic geometry. Short supplementary sections describe more advanced topics, further results, and unsolved problems.

Solid State Pathways towards Molecular Complexity in Space

Science.gov (United States)

Linnartz, Harold; Bossa, Jean-Baptiste; Bouwman, Jordy; Cuppen, Herma M.; Cuylle, Steven H.; van Dishoeck, Ewine F.; Fayolle, Edith C.; Fedoseev, Gleb; Fuchs, Guido W.; Ioppolo, Sergio; Isokoski, Karoliina; Lamberts, Thanja; Öberg, Karin I.; Romanzin, Claire; Tenenbaum, Emily; Zhen, Junfeng

2011-12-01

It has been a long standing problem in astrochemistry to explain how molecules can form in a highly dilute environment such as the interstellar medium. In the last decennium more and more evidence has been found that the observed mix of small and complex, stable and highly transient species in space is the cumulative result of gas phase and solid state reactions as well as gas-grain interactions. Solid state reactions on icy dust grains are specifically found to play an important role in the formation of the more complex ``organic'' compounds. In order to investigate the underlying physical and chemical processes detailed laboratory based experiments are needed that simulate surface reactions triggered by processes as different as thermal heating, photon (UV) irradiation and particle (atom, cosmic ray, electron) bombardment of interstellar ice analogues. Here, some of the latest research performed in the Sackler Laboratory for Astrophysics in Leiden, the Netherlands is reviewed. The focus is on hydrogenation, i.e., H-atom addition reactions and vacuum ultraviolet irradiation of interstellar ice analogues at astronomically relevant temperatures. It is shown that solid state processes are crucial in the chemical evolution of the interstellar medium, providing pathways towards molecular complexity in space.

Are Model Transferability And Complexity Antithetical? Insights From Validation of a Variable-Complexity Empirical Snow Model in Space and Time

Science.gov (United States)

Lute, A. C.; Luce, Charles H.

2017-11-01

The related challenges of predictions in ungauged basins and predictions in ungauged climates point to the need to develop environmental models that are transferable across both space and time. Hydrologic modeling has historically focused on modelling one or only a few basins using highly parameterized conceptual or physically based models. However, model parameters and structures have been shown to change significantly when calibrated to new basins or time periods, suggesting that model complexity and model transferability may be antithetical. Empirical space-for-time models provide a framework within which to assess model transferability and any tradeoff with model complexity. Using 497 SNOTEL sites in the western U.S., we develop space-for-time models of April 1 SWE and Snow Residence Time based on mean winter temperature and cumulative winter precipitation. The transferability of the models to new conditions (in both space and time) is assessed using non-random cross-validation tests with consideration of the influence of model complexity on transferability. As others have noted, the algorithmic empirical models transfer best when minimal extrapolation in input variables is required. Temporal split-sample validations use pseudoreplicated samples, resulting in the selection of overly complex models, which has implications for the design of hydrologic model validation tests. Finally, we show that low to moderate complexity models transfer most successfully to new conditions in space and time, providing empirical confirmation of the parsimony principal.

Low complexity wireless sensors for power-efficient communiation and energy harvesting

DEFF Research Database (Denmark)

Bo, Han

large antenna spacing and additional RF chains hinder its application to compact and battery powered devices. Wireless sensor networks are composed of such battery-powered devices, which require better energy efficiency in order to have a longer lifetime. Thus low complexity wireless sensors for power......The modern communication goes towards the direction of green, sustainable solutions; this raises many issues such as better usage of spectrum, lower system complexity, or lower energy consumption. MIMO transmission provides a promising solution with better spectral efficiency, but the required...... efficient communications are necessary. The beam space MIMO transmission approach was proposed recently for energy efficient communication; it uses only one RF chain and maps the MIMO data streams onto orthogonal basis radiation patterns. The resulting data streams appear at the receiver as originating from...

COTS low-cost 622-Mb/s free-space laser communications link for short-distance commercial applications

Science.gov (United States)

Morrison, Kenneth A.

2000-05-01

The results from a low cost 622 Mb/s, free-space laser communication link operating at 850 nm for short distance commercial applications is presented. The test results demonstrate the use of a free-space laser communications transceiver for building to building applications such as LAN, WAN and ATM operations, etc. This illustrates the potential for wide-use commercial computer network applications. The transceiver is constructed of commercial off-the-shelf materials for the development of a low-cost laser communications data link. The test system configuration utilizes standard Personal Computers with network cards and signal conversion cards for the copper to optical medical conversion. These tests precede the development of an increased data rate device operating at 2.5 Gb/s.

The role of space communication in promoting national development with specific reference to experiments conducted in India

Science.gov (United States)

Chitnis, E. V.

The paper describes the role of space communication in promoting national development with special reference to experiments conducted in India, namely SITE (1975-1976), STEP (1977-1979) and APPLE (1981 onwards). The impact of these experiments in economic, cultural and educational terms are discussed, pointing out social implications involved in using advance space communication technology for instruction and information in the areas of education, national integration and development. The paper covers special requirements which arise when a communication system covers backward and remote rural areas in a developing country. The impact on the population measured by conducting social surveys has been discussed - especially the gains of predominently illiterate new media - participants have been highlighted. Possibilities of improving skills of teachers, the quality of the primary and higher education have been covered. The preparation required both on ground as well as space to derive benefits of space technology are considered. A profile of INSAT which marks the culmination of the experimental phase and the beginning of operational domestic satellite system is sketched.

Differential phase-shift keying and channel equalization in free space optical communication system

Science.gov (United States)

Zhang, Dai; Hao, Shiqi; Zhao, Qingsong; Wan, Xiongfeng; Xu, Chenlu

2018-01-01

We present the performance benefits of differential phase-shift keying (DPSK) modulation in eliminating influence from atmospheric turbulence, especially for coherent free space optical (FSO) communication with a high communication rate. Analytic expression of detected signal is derived, based on which, homodyne detection efficiency is calculated to indicate the performance of wavefront compensation. Considered laser pulses always suffer from atmospheric scattering effect by clouds, intersymbol interference (ISI) in high-speed FSO communication link is analyzed. Correspondingly, the channel equalization method of a binormalized modified constant modulus algorithm based on set-membership filtering (SM-BNMCMA) is proposed to solve the ISI problem. Finally, through the comparison with existing channel equalization methods, its performance benefits of both ISI elimination and convergence speed are verified. The research findings have theoretical significance in a high-speed FSO communication system.

Making media work in space: an interdisciplinary perspective on media and communication requirements for current and future space communities

Science.gov (United States)

Babidge, S.; Cokley, J.; Gordon, F.; Louw, E.

2005-10-01

As humans expand into space communities will form. These have already begun to form in small ways, such as long-duration missions on the International Space Station and the space shuttle, and small-scale tourist excursions into space. Social, behavioural and communications data emerging from such existing communities in space suggest that the physically-bounded, work-oriented and traditionally male-dominated nature of these extremely remote groups present specific problems for the resident astronauts, groups of them viewed as ‘communities’, and their associated groups who remain on Earth, including mission controllers, management and astronauts’ families. Notionally feminine group attributes such as adaptive competence, social adaptation skills and social sensitivity will be crucial to the viability of space communities and in the absence of gender equity, ‘staying in touch’ by means of ‘news from home’ becomes more important than ever. A template of news and media forms and technologies is suggested to service those needs and enhance the social viability of future terraforming activities.

A multi-rate DPSK modem for free-space laser communications

Science.gov (United States)

Spellmeyer, N. W.; Browne, C. A.; Caplan, D. O.; Carney, J. J.; Chavez, M. L.; Fletcher, A. S.; Fitzgerald, J. J.; Kaminsky, R. D.; Lund, G.; Hamilton, S. A.; Magliocco, R. J.; Mikulina, O. V.; Murphy, R. J.; Rao, H. G.; Scheinbart, M. S.; Seaver, M. M.; Wang, J. P.

2014-03-01

The multi-rate DPSK format, which enables efficient free-space laser communications over a wide range of data rates, is finding applications in NASA's Laser Communications Relay Demonstration. We discuss the design and testing of an efficient and robust multi-rate DPSK modem, including aspects of the electrical, mechanical, thermal, and optical design. The modem includes an optically preamplified receiver, an 0.5-W average power transmitter, a LEON3 rad-hard microcontroller that provides the command and telemetry interface and supervisory control, and a Xilinx Virtex-5 radhard reprogrammable FPGA that both supports the high-speed data flow to and from the modem and controls the modem's analog and digital subsystems. For additional flexibility, the transmitter and receiver can be configured to support operation with multi-rate PPM waveforms.

2017 International Conference on Space Science and Communication

Science.gov (United States)

2017-05-01

Table of Content Preface 2017 International Conference on Space Science and Communication “Space Science for Sustainability” The present volume of the Journal of Physics: Conference Series represents contributions from participants of the 2017 International Conference on Space Science and Communication (IconSpace2017) held in Kuala Lumpur, Malaysia from May 3-5, 2017. The conference was organized by Space Science Centre (ANGKASA), Institute of Climate Change, Universiti Kebangsaan Malaysia (UKM) with a theme on “Space Science for Sustainability”. IconSpace2017 is the fifth series of conferences devoted to bringing researchers from around the world together to present and discuss their recent research results related to space science and communication, and also to provide an international platform for future research collaborations. This biennial international conference is an open forum where members in the field and others can meet in one place to discuss their current research findings. The technical program of this conference includes four keynote speakers, invited speakers, and the presentation of papers and poster. The track of the session includes Astrophysics and Astronomy, Atmospheric and Magnetospheric Sciences, Geoscience and Remote Sensing, Satellite and Communication Technology, and Interdisciplinary Space Science. Apart from the main conference, there will be a special talk on “Space Exploration & Updates” on 5 May 2017. More than 100 scientists and engineers from various academic, government, and industrial institutions in Europe, Asia, Australia, Africa, and the Americas attended the conference. The papers for this conference were selected after a rigorous review process. The papers were all evaluated by international and local reviewers and at least two reviewers were required to evaluate each paper. We should like to offer our thanks for the professionalism of the organizing committee, authors, reviewers, and volunteers deserve much

2017 International Conference on Space Science and Communication

International Nuclear Information System (INIS)

2017-01-01

Table of Content Preface 2017 International Conference on Space Science and Communication “Space Science for Sustainability” The present volume of the Journal of Physics: Conference Series represents contributions from participants of the 2017 International Conference on Space Science and Communication (IconSpace2017) held in Kuala Lumpur, Malaysia from May 3-5, 2017. The conference was organized by Space Science Centre (ANGKASA), Institute of Climate Change, Universiti Kebangsaan Malaysia (UKM) with a theme on “Space Science for Sustainability”. IconSpace2017 is the fifth series of conferences devoted to bringing researchers from around the world together to present and discuss their recent research results related to space science and communication, and also to provide an international platform for future research collaborations. This biennial international conference is an open forum where members in the field and others can meet in one place to discuss their current research findings. The technical program of this conference includes four keynote speakers, invited speakers, and the presentation of papers and poster. The track of the session includes Astrophysics and Astronomy, Atmospheric and Magnetospheric Sciences, Geoscience and Remote Sensing, Satellite and Communication Technology, and Interdisciplinary Space Science. Apart from the main conference, there will be a special talk on “Space Exploration and Updates” on 5 May 2017. More than 100 scientists and engineers from various academic, government, and industrial institutions in Europe, Asia, Australia, Africa, and the Americas attended the conference. The papers for this conference were selected after a rigorous review process. The papers were all evaluated by international and local reviewers and at least two reviewers were required to evaluate each paper. We should like to offer our thanks for the professionalism of the organizing committee, authors, reviewers, and volunteers deserve much

Power-law behavior in complex organizational communication networks during crisis

Science.gov (United States)

Uddin, Shahadat; Murshed, Shahriar Tanvir Hasan; Hossain, Liaquat

2011-08-01

Communication networks can be described as patterns of contacts which are created due to the flow of messages and information shared among participating actors. Contemporary organizations are now commonly viewed as dynamic systems of adaptation and evolution containing several parts, which interact with one another both in internal and in external environment. Although there is limited consensus among researchers on the precise definition of organizational crisis, there is evidence of shared meaning: crisis produces individual crisis, crisis can be associated with positive or negative conditions, crises can be situations having been precipitated quickly or suddenly or situations that have developed over time and are predictable etc. In this research, we study the power-law behavior of an organizational email communication network during crisis from complexity perspective. Power law simply describes that, the probability that a randomly selected node has k links (i.e. degree k) follows P(k)∼k, where γ is the degree exponent. We used social network analysis tools and techniques to analyze the email communication dataset. We tested two propositions: (1) as organization goes through crisis, a few actors, who are prominent or more active, will become central, and (2) the daily communication network as well as the actors in the communication network exhibit power-law behavior. Our preliminary results support these two propositions. The outcome of this study may provide significant advancement in exploring organizational communication network behavior during crisis.

[Communicating research with social media].

Science.gov (United States)

Bennato, Davide

2014-09-01

Participation is the new keyword of communication. In the scientific field, communication is a very complex task that can't ignore the careful consideration of the target audience. To minimize the difficulties, it is useful to rely on storytelling: it can greatly benefit from the space offered by social media that can be used to raise awareness and to engage through the sharing of experiences. The marriage between scientific research and social media can take place, as long as you carefully reflect on the roles, strategies and appropriate tools.

Novel Photon-Counting Detectors for Free-Space Communication

Science.gov (United States)

Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Lu, Wei; Merritt, Scott; Beck, Jeff

2016-01-01

We present performance data for novel photon counting detectors for free space optical communication. NASA GSFC is testing the performance of three novel photon counting detectors 1) a 2x8 mercury cadmium telluride avalanche array made by DRS Inc. 2) a commercial 2880 silicon avalanche photodiode array and 3) a prototype resonant cavity silicon avalanche photodiode array. We will present and compare dark count, photon detection efficiency, wavelength response and communication performance data for these detectors. We discuss system wavelength trades and architectures for optimizing overall communication link sensitivity, data rate and cost performance. The HgCdTe APD array has photon detection efficiencies of greater than 50 were routinely demonstrated across 5 arrays, with one array reaching a maximum PDE of 70. High resolution pixel-surface spot scans were performed and the junction diameters of the diodes were measured. The junction diameter was decreased from 31 m to 25 m resulting in a 2x increase in e-APD gain from 470 on the 2010 array to 1100 on the array delivered to NASA GSFC. Mean single photon SNRs of over 12 were demonstrated at excess noise factors of 1.2-1.3.The commercial silicon APD array has a fast output with rise times of 300ps and pulse widths of 600ps. Received and filtered signals from the entire array are multiplexed onto this single fast output. The prototype resonant cavity silicon APD array is being developed for use at 1 micron wavelength.

Conformal gravity, the Einstein equations and spaces of complex null geodesics

Energy Technology Data Exchange (ETDEWEB)

Baston, R.J.; Mason, L.J.

1987-07-01

The aim of the paper is to give a twistorial characterisation of the field equations of conformal gravity and of Einstein spacetimes. Strong evidence is provided for a particularly concise characterisation of these equations in terms of 'formal neighbourhoods'of the space of complex null geodesics. Second-order perturbations of the metric of complexified Minkowski space are considered. These correspond to certain infinitesimal deformations of its space of complex null geodesics, PN. PN has a natural codimension one embedding into a larger space. It is shown that deformations extend automatically to the fourth-order embedding (that is, the fourth formal neighbourhood). They extend to the fifth formal neighbourhood if and only if the corresponding perturbation in the metric has vanishing Bach tensor. Finally, deformations which extend to the sixth formal neighbourhood correspond to perturbations in the metric that are conformally related to ones satisfying the Einstein equations. The authors present arguments which suggest that the results will also hold when spacetime is fully curved.

Conformal gravity, the Einstein equations and spaces of complex null geodesics

International Nuclear Information System (INIS)

Baston, R.J.; Mason, L.J.

1987-01-01

The aim of the paper is to give a twistorial characterisation of the field equations of conformal gravity and of Einstein spacetimes. Strong evidence is provided for a particularly concise characterisation of these equations in terms of 'formal neighbourhoods'of the space of complex null geodesics. Second-order perturbations of the metric of complexified Minkowski space are considered. These correspond to certain infinitesimal deformations of its space of complex null geodesics, PN. PN has a natural codimension one embedding into a larger space. It is shown that deformations extend automatically to the fourth-order embedding (that is, the fourth formal neighbourhood). They extend to the fifth formal neighbourhood if and only if the corresponding perturbation in the metric has vanishing Bach tensor. Finally, deformations which extend to the sixth formal neighbourhood correspond to perturbations in the metric that are conformally related to ones satisfying the Einstein equations. The authors present arguments which suggest that the results will also hold when spacetime is fully curved. (author)

Low-Noise Free-Running High-Rate Photon-Counting for Space Communication and Ranging

Science.gov (United States)

Lu, Wei; Krainak, Michael A.; Yang, Guan; Sun, Xiaoli; Merritt, Scott

2016-01-01

We present performance data for low-noise free-running high-rate photon counting method for space optical communication and ranging. NASA GSFC is testing the performance of two types of novel photon-counting detectors 1) a 2x8 mercury cadmium telluride (HgCdTe) avalanche array made by DRS Inc., and a 2) a commercial 2880-element silicon avalanche photodiode (APD) array. We successfully measured real-time communication performance using both the 2 detected-photon threshold and logic AND-gate coincidence methods. Use of these methods allows mitigation of dark count, after-pulsing and background noise effects without using other method of Time Gating The HgCdTe APD array routinely demonstrated very high photon detection efficiencies (50) at near infrared wavelength. The commercial silicon APD array exhibited a fast output with rise times of 300 ps and pulse widths of 600 ps. On-chip individually filtered signals from the entire array were multiplexed onto a single fast output. NASA GSFC has tested both detectors for their potential application for space communications and ranging. We developed and compare their performances using both the 2 detected photon threshold and coincidence methods.

Some thoughts on the management of large, complex international space ventures

Science.gov (United States)

Lee, T. J.; Kutzer, Ants; Schneider, W. C.

1992-01-01

Management issues relevant to the development and deployment of large international space ventures are discussed with particular attention given to previous experience. Management approaches utilized in the past are labeled as either simple or complex, and signs of efficient management are examined. Simple approaches include those in which experiments and subsystems are developed for integration into spacecraft, and the Apollo-Soyuz Test Project is given as an example of a simple multinational approach. Complex approaches include those for ESA's Spacelab Project and the Space Station Freedom in which functional interfaces cross agency and political boundaries. It is concluded that individual elements of space programs should be managed by individual participating agencies, and overall configuration control is coordinated by level with a program director acting to manage overall objectives and project interfaces.

On the Communication Complexity of Secure Function Evaluation with Long Output

DEFF Research Database (Denmark)

Hubacek, Pavel; Wichs, Daniel

2015-01-01

We study the communication complexity of secure function evaluation (SFE). Consider a setting where Alice has a short input χA, Bob has an input χB and we want Bob to learn some function y = f(χA, χB) with large output size. For example, Alice has a small secret decryption key, Bob has a large...... value. Moreover, we show that even in an offline/online protocol, the communication of the online phase must have output-size dependence. This negative result uses an incompressibility argument and it generalizes several recent lower bounds for functional encryption and (reusable) garbled circuits...

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...

Small-Scale Design Experiments as Working Space for Larger Mobile Communication Challenges

Science.gov (United States)

Lowe, Sarah; Stuedahl, Dagny

2014-01-01

In this paper, a design experiment using Instagram as a cultural probe is submitted as a method for analyzing the challenges that arise when considering the implementation of social media within a distributed communication space. It outlines how small, iterative investigations can reveal deeper research questions relevant to the education of…

A sense of change: media designers and artists communicating about complexity in social-ecological systems

Directory of Open Access Journals (Sweden)

Joost M. Vervoort

2014-09-01

Full Text Available To take on the current and future challenges of global environmental change, fostering a widespread societal understanding of and engagement with the complex dynamics that characterize interacting human and natural systems is essential. Current science communication methods struggle with a number of specific challenges associated with communicating about complex systems. In this study we report on two collaborative processes, a short workshop and longer course, that aimed to harness the insights of interactive media designers and artists to overcome these challenges. The two processes resulted in 86 new interactive media concepts which were selected by the participants and organizers using set criteria and then evaluated using the same criteria by a panel of communication and media design experts and a panel of complex systems scientists using the same criteria. The top eight concepts are discussed in this paper. These concepts fell into the categories of serious games, group interaction concepts, and social media storytelling. The serious games focused directly on complex systems characteristics and were evaluated to be intuitive and engaging designs that combined transparency and complexity well. The group interaction concepts focused mostly on feedbacks and nonlinearity but were fully developed and tested in the workshops, and evaluated as engaging, accessible, and easy to implement in workshops and educational settings. The social media storytelling concepts involved less direct interactions with system dynamics but were seen as highly accessible to large scale audiences. The results of this study show the potential of interdisciplinary collaboration between complex systems scientists, designers, and artists. The results and process discussed in this paper show the value of more structural engagement of interactive media designers and artist communities in the development of communication tools about human and natural systems change.

A multi-element cosmological model with a complex space-time topology

Science.gov (United States)

Kardashev, N. S.; Lipatova, L. N.; Novikov, I. D.; Shatskiy, A. A.

2015-02-01

Wormhole models with a complex topology having one entrance and two exits into the same space-time of another universe are considered, as well as models with two entrances from the same space-time and one exit to another universe. These models are used to build a model of a multi-sheeted universe (a multi-element model of the "Multiverse") with a complex topology. Spherical symmetry is assumed in all the models. A Reissner-Norström black-hole model having no singularity beyond the horizon is constructed. The strength of the central singularity of the black hole is analyzed.

Communication Research in Aviation and Space Operations: Symptoms and Strategies of Crew Coordination

Science.gov (United States)

Kanki, Barbara G.; Hart, Sandra G. (Technical Monitor)

1994-01-01

The day-to-day operators of today's aerospace systems work under increasing pressures to accomplish more with less. They work in operational systems which are complex, technology-based, and high-risk; in which incidents and accidents have far-reaching and costly consequences. For these and other reasons, there is concern that the safety net formerly built upon redundant systems and abundant resources may become overburdened. Although we know that human ingenuity can overcome incredible odds, human nature can also fail in unpredictable ways. Over the last 20 years, a large percentage of aviation accidents and incidents have been attributed to human errors rather than hardware or environmental factors alone. A class of errors have been identified which are not due to a lack of individual, technical competencies. Rather, they are due to the failure of teams to utilize readily available resources or information in a timely fashion. These insights began a training revolution in the aviation industry called Cockpit Resource Management, which later became known as Crew Resource Management (CRM) as its concepts and applications extended to teams beyond the flightdeck. Then, as now, communication has been a cornerstone in CRM training since crew coordination and resource management largely resides within information transfer processes--both within flightcrews, and between flightcrews and the ground operations teams that support them. The research I will describe takes its roots in CRM history as we began to study communication processes in order to discover symptoms of crew coordination problems, as well as strategies of effective crew management. On the one hand, communication is often the means or the tool by which team members manage their resources, solve problems, maintain situational awareness and procedural discipline. Conversely, it is the lack of planning and resource management, loss of vigilance and situational awareness, and non-standard communications that are

A novel sort of adaptive complex synchronizations of two indistinguishable chaotic complex nonlinear models with uncertain parameters and its applications in secure communications

Science.gov (United States)

Mahmoud, Emad E.; Abood, Fatimah S.

In this paper, we will demonstrate the adaptive complex anti-lag synchronization (CALS) of two indistinguishable complex chaotic nonlinear systems with the parameters which are uncertain. The significance of CALS is not advised well in the literature yet. The CALS contains or consolidate two sorts of synchronizations (anti-lag synchronization ALS and lag synchronization LS). The state variable of the master system synchronizes with an alternate state variable of the slave system. Depending on the function of Lyapunov, a plan is orchestrated to achieve CALS of chaotic attractors of complex systems with unverifiable parameters. CALS of two indistinguishable complexes of Lü systems is viewed as, for example, an occasion for affirming the likelihood of the plan exhibited. In physics, we can see complex chaotic systems in numerous different applications, for example, applied sciences or engineering. With a specific end goal to affirm the proposed synchronization plan viability and demonstrate the hypothetical outcomes, we can compute the numerical simulation. The above outcomes will give the hypothetical establishment to the secure communication applications. CALS of complex chaotic systems in which a state variable of the master system synchronizes with an alternate state variable of the slave system is an encouraging sort of synchronization as it contributes excellent security in secure communication. Amid this secure communication, the synchronization between transmitter and collector is shut and message signals are recouped. The encryption and restoration of the signals are simulated numerically.

The Synthesis Method of Automated System of Operational Planning in Low-Space Communication System Messaging

Directory of Open Access Journals (Sweden)

Serhii Kovbasiuk

2017-04-01

Full Text Available One of the reasons for the decrease of efficiency in low-speed communication systems, satellite communication, which are based on nanoplatform is a high degree of operational planning centralisation. To overcome this problem the method which carries out the distribution of tasks of communications operational planning minimizing the exchange of information between spatially remote sites, and takes into account the computing performance of software and hardware was developed. The technique is based on the use of methods of structural and parametric synthesis, simulation and statistical analysis of the results. Its use allows to obtain the optimal structure of the automated system of operational planning in low-space communication system messaging evaluation of efficiency in terms of fixed communication of information load.

Free Space Optical (FSO) Communications, Towards the Speeds of Wireline Networks

KAUST Repository

Alouini, Mohamed-Slim

2015-01-07

Rapid increase in the use of wireless services over the last two decades has lead the problem of the radio-frequency (RF) spectrum exhaustion. More specifically, due to this RF spectrum scarcity, additional RF bandwidth allocation, as utilized in the recent past, is not anymore a viable solution to fulfill the demand for more wireless applications and higher data rates. Among the many proposed solutions, optical wireless communication or free-space optical (FSO) systems have gained an increasing interest due to their advantages including higher bandwidth and higher capacity compared to the traditional RF communication systems. This promising technology offers full-duplex Gigabit throughput in certain applications and environment while benefiting from a huge license-free spectrum, immunity to interference, and high security. These features of FSO communication systems potentially enable solving the issues that the RF communication systems face due to the expensive and scarce RF spectrum. The first part of the talk will give an overview of FSO communication systems by offering examples of advantages and application areas of this emerging technology. In the second part of talk, we will focus on some recent results and on-going research directions in the accurate characterization of the performance of FSO systems in the presence of inevitable impairments due to atmospheric turbulence and misalignment between transmitter and receiver.

Cyber space bullying

Directory of Open Access Journals (Sweden)

Popović-Ćitić Branislava

2009-01-01

Full Text Available Cyber space bullying is a relatively new phenomenon that has received increased attention by scientists, researchers and practitioners in recent years. It is usually defined as an intentionally and repeatedly expression of aggression towards other people through information and communication technologies. Cyber space bullying is characterized by all the primary characteristics of traditional bullying and some specifics ones that clearly differ it from other forms of bullying. In addition to the analysis of characteristics and specifics of cyber space bullying, the paper describes the basic forms of cyber space bullying (flaming, harassment, denigration, impersonation, outing, trickery, exclusion, stalking and happy slapping, as well as, the types of cyber space bullies (vengeful angel, power-hungry, revenge of the nerd, mean girls and inadvertent. The main goal of this paper is to provide initial theoretical guidelines for designing future empirical research on the complex phenomenon of cyber space bullying.

Relativistic effects on complexity indexes in atoms in position and momentum spaces

International Nuclear Information System (INIS)

Maldonado, P.; Sarsa, A.; Buendia, E.; Galvez, F.J.

2010-01-01

Three different statistical measures of complexity are explored for the atoms He to Ra. The measures are analysed in both position and momentum spaces. Relativistic effects on the complexity indexes are systematically studied. These effects are discussed in terms of the information content factor and the disorder terms of the complexity indexes. Relativistic and non-relativistic complexity indexes are calculated from Optimized Effective Potential densities.

Patient-centred communication intervention study to evaluate nurse-patient interactions in complex continuing care

Science.gov (United States)

2012-01-01

Background Communication impairment is a frequent consequence of stroke. Patients who cannot articulate their needs respond with frustration and agitation, resulting in poor optimization of post-stroke functions. A key component of patient-centred care is the ability of staff to communicate in a way that allows them to understand the patient’s needs. We developed a patient-centred communication intervention targeting registered and unregulated nursing staff caring for complex continuing care patients with communication impairments post stroke. Research objectives include 1) examining the effects of the intervention on patients’ quality of life, depression, satisfaction with care, and agitation; and (2) examining the extent to which the intervention improves staff’s attitudes and knowledge in caring for patients with communication impairments. The intervention builds on a previous pilot study. Methods/design A quasi-experimental repeated measures non-equivalent control group design in a complex continuing care facility is being used. Patients with a communication impairment post-stroke admitted to the facility are eligible to participate. All staff nurses are eligible. Baseline data are collected from staff and patients. Follow-up will occur at 1 and 3 months post-intervention. Subject recruitment and data collection from 60 patients and 30 staff will take approximately 36 months. The Patient-Centred Communication Intervention consists of three components: (1) development of an individualized patient communication care plan; (2) a one-day workshop focused on communication and behavioural management strategies for nursing staff; and (3) a staff support system. The intervention takes comprehensive patient assessments into account to inform the development of communication and behavioural strategies specifically tailored to each patient. Discussion The Patient-Centred Communication Intervention will provide staff with strategies to facilitate interactions with

Patient-centred communication intervention study to evaluate nurse-patient interactions in complex continuing care

Directory of Open Access Journals (Sweden)

McGilton Katherine S

2012-10-01

Full Text Available Abstract Background Communication impairment is a frequent consequence of stroke. Patients who cannot articulate their needs respond with frustration and agitation, resulting in poor optimization of post-stroke functions. A key component of patient-centred care is the ability of staff to communicate in a way that allows them to understand the patient’s needs. We developed a patient-centred communication intervention targeting registered and unregulated nursing staff caring for complex continuing care patients with communication impairments post stroke. Research objectives include 1 examining the effects of the intervention on patients’ quality of life, depression, satisfaction with care, and agitation; and (2 examining the extent to which the intervention improves staff’s attitudes and knowledge in caring for patients with communication impairments. The intervention builds on a previous pilot study. Methods/design A quasi-experimental repeated measures non-equivalent control group design in a complex continuing care facility is being used. Patients with a communication impairment post-stroke admitted to the facility are eligible to participate. All staff nurses are eligible. Baseline data are collected from staff and patients. Follow-up will occur at 1 and 3 months post-intervention. Subject recruitment and data collection from 60 patients and 30 staff will take approximately 36 months. The Patient-Centred Communication Intervention consists of three components: (1 development of an individualized patient communication care plan; (2 a one-day workshop focused on communication and behavioural management strategies for nursing staff; and (3 a staff support system. The intervention takes comprehensive patient assessments into account to inform the development of communication and behavioural strategies specifically tailored to each patient. Discussion The Patient-Centred Communication Intervention will provide staff with strategies to

850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes

DEFF Research Database (Denmark)

Jurado-Navas, Antonio; Tatarczak, Anna; Lu, Xiaofeng

2015-01-01

Light beams can carry orbital angular momentum (OAM) associated to the helicity of their phasefronts. These OAM modes can be employed to encode information onto a laser beam for transmitting not only in a fiber link but also in a free-space optical (FSO) one. Regarding this latter scenario, FSO...... communications are considered as an alternative and promising mean complementing the traditional optical communications in many applications where the use of fiber cable is not justified. This next generation FSO communication systems have attracted much interest recently, and the inclusion of beams carrying OAM...... modes can be seen as an efficient solution to increase the capacity and the security in the link. In this paper, we discuss an experimental demonstration of a proposal for next generation FSO communication system where a light beam carrying different OAM modes and affected by M turbulence is coupled...

Common Fixed Points of Generalized Cocyclic Mappings in Complex Valued Metric Spaces

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Mujahid Abbas

2015-01-01

Full Text Available We present fixed point results of mappings satisfying generalized contractive conditions in complex valued metric spaces. As an application, we obtain a common fixed point of a pair of weakly compatible mappings. Some common fixed point results of generalized contractive-type mappings involved in cocyclic representation of a nonempty subset of a complex valued metric space are also obtained. Some examples are also presented to support the results proved herein. These results extend and generalize many results in the existing literature.

An Improved Conceptually-Based Method for Analysis of Communication Network Structure of Large Complex Organizations.

Science.gov (United States)

Richards, William D., Jr.

Previous methods for determining the communication structure of organizations work well for small or simple organizations, but are either inadequate or unwieldy for use with large complex organizations. An improved method uses a number of different measures and a series of successive approximations to order the communication matrix such that…

Aspects of scintillation modelling in LEO-ground free-space optical communications

Science.gov (United States)

Moll, Florian

2017-10-01

Free-space optical communications can be used to transmit data from low Earth orbit satellites to ground with very high data rate. In the last section of the downlink, the electro-magnetic wave propagates through the turbulent atmosphere which is characterized by random index of refraction fluctuations. The propagating wave experiences phase distortions that lead to intensity scintillation in the aperture plane of the receiving telescope. For quantification, an appropriate scintillation model is needed. Approaches to analytically model the scintillation exist. Parameterization of the underlying turbulence profile (Cn2 profile) is however difficult. The Cn2 profiles are often site-specific and thus inappropriate or generic and thus too complex for a feasible deployment. An approach that directly models the scintillation effect based on measurements without claiming to be generic is therefore more feasible. Since measurements are sparse, a combination with existing theoretical framework is feasible to develop a new scintillation model that focuses on low earth orbit to ground free-space optical communications link design with direct detection. The paper addresses several questions one has to answer while analyzing the measurements data and selection of the theoretical models for the LEO downlink scenario. The first is the question of a suitable yet ease to use simple Cn2 profile. The HAP model is analyzed for its feasibility in this scenario since it includes a more realistic boundary layer profile decay than the HV model. It is found that the HAP model needs to be modified for a feasible deployment in the LEO downlink scenario for night time. The validity of the plane wave assumption in the downlink is discussed by model calculations of the scintillation index for a plane and Gaussian beam wave. Inaccuracies when using the plane earth model instead of the spherical earth model are investigated by analyzing the Rytov index. Impact of beam wander and non

Lower Bounds for Number-in-Hand Multiparty Communication Complexity, Made Easy

DEFF Research Database (Denmark)

Phillips, Jeff; Verbin, Elad; Zhang, Qin

2012-01-01

; the technique seems applicable to a wide range of other problems as well. The obtained communication lower bounds imply new lower bounds in the functional monitoring model [11] (also called the distributed streaming model). All of our lower bounds allow randomized communication protocols with two-sided error......In this paper we prove lower bounds on randomized multiparty communication complexity, both in the blackboard model (where each message is written on a blackboard for all players to see) and (mainly) in the message-passing model, where messages are sent player-to-player. We introduce a new...... technique for proving such bounds, called symmetrization, which is natural, intuitive, and often easy to use. For example, for the problem where each of k players gets a bit-vector of length n, and the goal is to compute the coordinate-wise XOR of these vectors, we prove a tight lower bounds of Ω...

Communication-Oriented Design Space Exploration for Reconfigurable Architectures

Directory of Open Access Journals (Sweden)

Gogniat Guy

2007-01-01

Full Text Available Many academic works in computer engineering focus on reconfigurable architectures and associated tools. Fine-grain architectures, field programmable gate arrays (FPGAs, are the most well-known structures of reconfigurable hardware. Dedicated tools (generic or specific allow for the exploration of their design space to choose the best architecture characteristics and/or to explore the application characteristics. The aim is to increase the synergy between the application and the architecture in order to get the best performance. However, there is no generic tool to perform such an exploration for coarse-grain or heterogeneous-grain architectures, just a small number of very specific tools are able to explore a limited set of architectures. To address this major lack, in this paper we propose a new design space exploration approach adapted to fine- and coarse-grain granularities. Our approach combines algorithmic and architecture explorations. It relies on an automatic estimation tool which computes the communication hierarchical distribution and the architectural processing resources use rate for the architecture under exploration. Such an approach forwards the rapid definition of efficient reconfigurable architectures dedicated to one or several applications.

Planets as background noise sources in free space optical communications

Science.gov (United States)

Katz, J.

1986-01-01

Background noise generated by planets is the dominant noise source in most deep space direct detection optical communications systems. Earlier approximate analyses of this problem are based on simplified blackbody calculations and can yield results that may be inaccurate by up to an order of magnitude. Various other factors that need to be taken into consideration, such as the phase angle and the actual spectral dependence of the planet albedo, in order to obtain a more accurate estimate of the noise magnitude are examined.

ASSESSMENT OF STUDENT LEARNING IN VIRTUAL SPACES, USING ORDERS OF COMPLEXITY IN LEVELS OF THINKING

Directory of Open Access Journals (Sweden)

Jose CAPACHO

2017-04-01

Full Text Available This paper aims at showing a new methodology to assess student learning in virtual spaces supported by Information and Communications Technology-ICT. The methodology is based on the Conceptual Pedagogy Theory, and is supported both on knowledge instruments (KI and intelectual operations (IO. KI are made up of teaching materials embedded in the virtual environment. The student carries out IO in his/her virtual formation process based on KI. Both instruments of knowledge and intellectual operations can be mathematically modelled by using functions of increasing complexity order. These functions represent the student’s learning change. This paper main contribution is to show that these functions let the student go from a concrete thinking to a formal one in his/her virtual learning process. The research showed that 47% of the students moved from a concrete thinking level to the formal thinking level.

Complexity Science and the Dynamics of Climate and Communication: Reducing Nursing Home Turnover

Science.gov (United States)

Anderson, Ruth A.; Corazzini, Kirsten N.; McDaniel, Reuben R.

2008-01-01

Purpose Turnover in nursing homes is a widespread problem adversely affecting care quality. Using complexity theory, we tested the effect of administrative climate, communication patterns, and the interaction between the two on turnover, controlling for facility context. Design and Methods Perceptions of administrative climate and communication were collected from 3,449 employees in 164 randomly sampled nursing homes, and they were linked to secondary data on facility characteristics, resource allocation, and turnover. We used hierarchical regression to test the hypotheses. Results Climate and communication both affected turnover, but lower turnover was dependent on the interaction between climate and communication. In nursing homes with reward-based administrative climates, higher levels of communication openness and accuracy explained lower turnover of licensed vocational nurses and certified nurse assistants, relative to nursing homes with an ambiguous climate. Adequate staffing and longer tenure of the nursing director were also important predictors of turnover. Implications Although context is important, managers can also influence turnover by addressing climate and communication patterns and by encouraging stable nursing leadership. PMID:15197292

Arms applied to the communications system at the Kourou space centre

International Nuclear Information System (INIS)

Gerez Martin, L.; Garcia de la Sen, R.

1993-01-01

The REMUS (Roseau d'Entreprise MUltiService) has been designed to cover present and future communications needs which are associated with daily operation of the Guyanese Space Centre (GSC). This communications network will facilitate data exchange, contain the data (RSD) and voice network, and paging (RRP), convoy (RCV) and telephony (RSV) systems. The main objectives of the study were: 1. To assess system availability. 2. To dimension spare parts of the renewal equipment and define the logistic delays to be observed in order to achieve an availability target of: - 99.9% for the RRP, RCV and RSV networks. - 99.9% for the RSD network. The RAMSES program developed by Empresarios Agrupados was used in these calculations, to evaluate system behaviour by means of a Monte Carlo simulation. (author)

The Association of Schools of Journalism and mass communication journalist-in-space project

Science.gov (United States)

1986-01-01

During the summer of 1985, NASA asked the Association of Schools of Journalism and Mass Communication (ASJMC) to select a U. S. journalist who could ride aboard the space shuttle and report the experience to the American public. Eligibility critieria and selection procedures are discussed. The forty semifinalists are listed.

The impact of emotional intelligence, self-esteem, and self-image on romantic communication over MySpace.

Science.gov (United States)

Dong, Qingwen; Urista, Mark A; Gundrum, Duane

2008-10-01

A study based on a survey of 240 individual MySpace users found that low self-esteem encourages young adults to engage in romantic communication (such as having intimate communication with the opposite sex and looking for romantic partners) while higher emotional intelligence discourages such activity. The results also suggested that those who have higher self-image, such as thinking themselves attractive and happy with their appearance, tend to engage in romantic communication. Limitations of the study and suggestion for future study are discussed.

Mobile free-space optical communications: a feasibility study of various battlefield scenarios

Science.gov (United States)

Harris, Alan; Al-Akkoumi, Mouhammad K.; Sluss, James J., Jr.

2012-06-01

Free Space Optics (FSO) technology was originally envisioned to be a viable solution for the provision of high bandwidth optical connectivity in the last mile of today's telecommunications infrastructure. Due to atmospheric limitations inherent to FSO technology, FSO is now widely envisioned as a solution for the provision of high bandwidth, temporary mobile communications links. The need for FSO communications links will increase as mobility is introduced to this technology. In this paper, a theoretical solution for adding mobility to FSO communication links is introduced. Three-dimensional power estimation studies are presented to represent mobile FSO transmission under various weather conditions. Three wavelengths, 0.85, 1.55 and 10 um, are tested and compared to illustrate the pros and cons of each source wavelength used for transmission, depending on prevalent weather conditions and atmospheric turbulence conditions. A simulation analysis of the transmission properties of the source wavelengths used in the study is shown.

Space-time complexity in solid state models

International Nuclear Information System (INIS)

Bishop, A.R.

1985-01-01

In this Workshop on symmetry-breaking it is appropriate to include the evolving fields of nonlinear-nonequilibrium systems in which transitions to and between various degrees of ''complexity'' (including ''chaos'') occur in time or space or both. These notions naturally bring together phenomena of pattern formation and chaos and therefore have ramifications for a huge array of natural sciences - astrophysics, plasmas and lasers, hydrodynamics, field theory, materials and solid state theory, optics and electronics, biology, pattern recognition and evolution, etc. Our particular concerns here are with examples from solid state and condensed matter

The communication of heritage: Assessment of the communicative process in museums of Asturias

Directory of Open Access Journals (Sweden)

Miguel Ángel SUÁREZ SUÁREZ

2017-06-01

Full Text Available Communicating of heritage, especially in museums, is a complex process due to certain particularities. Each museum is unique because of the diversity of objects, the discourses generated and the interactions between different audiences. It makes it difficult to build theories which help to understand and improve the communicative process with in the museum context. In this way, from prior studies and through both a direct observation and monitoring of the guided visits, this work shows the analysis of 7 museums from Asturias, focusing on the spatial distribution, the museography and the interventions of the teachers and students. The results show that museums are making an ef-fort to set up multidirectional communication models, doing a coherent design between exhibition spaces, the ob-jects’ museography and the teachers’ explanation. Nevertheless, there are some problems which impede a full con-nection between the school and the museum, which limit the effective communication of the message about herit-age.

K-best decoders for 5G+ wireless communication

CERN Document Server

Rahman, Mehnaz

2017-01-01

This book discusses new, efficient and hardware realizable algorithms that can attain the performance of beyond 5G wireless communication. The authors explain topics gradually, stepping from basic MIMO detection to optimized schemes for both hard and soft domain MIMO detection and also to the feasible VLSI implementation, scalable to any MIMO configuration (including massive MIMO, used in satellite/space communication). The techniques described in this book enable readers to implement real designs, with reduced computational complexity and improved performance.

Geostationary Communications Satellites as Sensors for the Space Weather Environment: Telemetry Event Identification Algorithms

Science.gov (United States)

Carlton, A.; Cahoy, K.

2015-12-01

Reliability of geostationary communication satellites (GEO ComSats) is critical to many industries worldwide. The space radiation environment poses a significant threat and manufacturers and operators expend considerable effort to maintain reliability for users. Knowledge of the space radiation environment at the orbital location of a satellite is of critical importance for diagnosing and resolving issues resulting from space weather, for optimizing cost and reliability, and for space situational awareness. For decades, operators and manufacturers have collected large amounts of telemetry from geostationary (GEO) communications satellites to monitor system health and performance, yet this data is rarely mined for scientific purposes. The goal of this work is to acquire and analyze archived data from commercial operators using new algorithms that can detect when a space weather (or non-space weather) event of interest has occurred or is in progress. We have developed algorithms, collectively called SEER (System Event Evaluation Routine), to statistically analyze power amplifier current and temperature telemetry by identifying deviations from nominal operations or other events and trends of interest. This paper focuses on our work in progress, which currently includes methods for detection of jumps ("spikes", outliers) and step changes (changes in the local mean) in the telemetry. We then examine available space weather data from the NOAA GOES and the NOAA-computed Kp index and sunspot numbers to see what role, if any, it might have played. By combining the results of the algorithm for many components, the spacecraft can be used as a "sensor" for the space radiation environment. Similar events occurring at one time across many component telemetry streams may be indicative of a space radiation event or system-wide health and safety concern. Using SEER on representative datasets of telemetry from Inmarsat and Intelsat, we find events that occur across all or many of

GPS and Galileo Developments on Board the International Space Station With the Space Communications and Navigation (SCaN) Testbed

Science.gov (United States)

Pozzobon, Oscar; Fantinato, Samuele; Dalla Chiara, Andrea; Gamba, Giovanni; Crisci, Massimo; Giordana, Pietro; Enderle, Werner; Chelmins, David; Sands, Obed S.; Clapper, Carolyn J.;

EPR & Klein Paradoxes in Complex Hamiltonian Dynamics and Krein Space Quantization

Science.gov (United States)

Payandeh, Farrin

2015-07-01

Negative energy states are applied in Krein space quantization approach to achieve a naturally renormalized theory. For example, this theory by taking the full set of Dirac solutions, could be able to remove the propagator Green function's divergences and automatically without any normal ordering, to vanish the expected value for vacuum state energy. However, since it is a purely mathematical theory, the results are under debate and some efforts are devoted to include more physics in the concept. Whereas Krein quantization is a pure mathematical approach, complex quantum Hamiltonian dynamics is based on strong foundations of Hamilton-Jacobi (H-J) equations and therefore on classical dynamics. Based on complex quantum Hamilton-Jacobi theory, complex spacetime is a natural consequence of including quantum effects in the relativistic mechanics, and is a bridge connecting the causality in special relativity and the non-locality in quantum mechanics, i.e. extending special relativity to the complex domain leads to relativistic quantum mechanics. So that, considering both relativistic and quantum effects, the Klein-Gordon equation could be derived as a special form of the Hamilton-Jacobi equation. Characterizing the complex time involved in an entangled energy state and writing the general form of energy considering quantum potential, two sets of positive and negative energies will be realized. The new states enable us to study the spacetime in a relativistic entangled “space-time” state leading to 12 extra wave functions than the four solutions of Dirac equation for a free particle. Arguing the entanglement of particle and antiparticle leads to a contradiction with experiments. So, in order to correct the results, along with a previous investigation [1], we realize particles and antiparticles as physical entities with positive energy instead of considering antiparticles with negative energy. As an application of modified descriptions for entangled (space

Performance Analysis of Free-Space Optical Communication Systems With Multiuser Diversity Over Atmospheric Turbulence Channels

KAUST Repository

Yang, Liang; Gao, Xiqi; Alouini, Mohamed-Slim

2014-01-01

Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD

Complex Teichmüller Space below the Planck Length for the Interpretation of Quantum Mechanics

Science.gov (United States)

Winterberg, Friedwardt

2014-03-01

As Newton's mysterious action at a distance law of gravity was explained as a Riemannian geometry by Einstein, it is proposed that the likewise mysterious non-local quantum mechanics is explained by the analytic continuation below the Planck length into a complex Teichmüller space. Newton's theory worked extremely well, as does quantum mechanics, but no satisfactory explanation has been given for quantum mechanics. In one space dimension, sufficient to explain the EPR paradox, the Teichmüller space is reduced to a space of complex Riemann surfaces. Einstein's curved space-time theory of gravity was confirmed by a tiny departure from Newton's theory in the motion of the planet Mercury, and an experiment is proposed to demonstrate the possible existence of a Teichmüller space below the Planck length.

An Array of Optical Receivers for Deep-Space Communications

Science.gov (United States)

Vilnrotter, Chi-Wung; Srinivasan, Meera; Andrews, Kenneth

2007-01-01

An array of small optical receivers is proposed as an alternative to a single large optical receiver for high-data-rate communications in NASA s Deep Space Network (DSN). Because the telescope for a single receiver capable of satisfying DSN requirements must be greater than 10 m in diameter, the design, building, and testing of the telescope would be very difficult and expensive. The proposed array would utilize commercially available telescopes of 1-m or smaller diameter and, therefore, could be developed and verified with considerably less difficulty and expense. The essential difference between a single-aperture optical-communications receiver and an optical-array receiver is that a single-aperture receiver focuses all of the light energy it collects onto the surface of an optical detector, whereas an array receiver focuses portions of the total collected energy onto separate detectors, optically detects each fractional energy component, then combines the electrical signal from the array of detector outputs to form the observable, or "decision statistic," used to decode the transmitted data. A conceptual block diagram identifying the key components of the optical-array receiver suitable for deep-space telemetry reception is shown in the figure. The most conspicuous feature of the receiver is the large number of small- to medium-size telescopes, with individual apertures and number of telescopes selected to make up the desired total collecting area. This array of telescopes is envisioned to be fully computer- controlled via the user interface and prediction-driven to achieve rough pointing and tracking of the desired spacecraft. Fine-pointing and tracking functions then take over to keep each telescope pointed toward the source, despite imperfect pointing predictions, telescope-drive errors, and vibration caused by wind.

Final Report: 03-LW-005 Space-Time Secure Communications for Hostile Environments

Energy Technology Data Exchange (ETDEWEB)

Candy, J V; Poggio, A J; Chambers, D H; Guidry, B L; Robbins, C L; Hertzog, C A; Dowla, F; Burke, G; Kane, R

2005-10-31

The development of communications for highly reverberative environments is a major concern for both the private and military sectors whether the application is aimed at the securing a stock order or stalking hostile in a tunnel or cave. Other such environments can range from a hostile urban setting populated with a multitude of buildings and vehicles to the simple complexity of a large number of sound sources that are common in the stock exchange, or military operations in an environment with a topographic features hills, valleys, mountains or even a maze of buried water pipes attempting to transmit information about any chemical anomalies in the water system servicing a city or town. These inherent obstructions cause transmitted signals to reflect, refract and disperse in a multitude of directions distorting both their shape and arrival times at network receiver locations. Imagine troops attempting to communicate on missions in underground caves consisting of a maze of chambers causing multiple echoes with the platoon leader trying to issue timely commands to neutralize terrorists. This is the problem with transmitting information in a complex environment. Waves are susceptible to multiple paths and distortions created by a variety of possible obstructions, which may exist in the particular propagation medium. This is precisely the communications problem we solve using the physics of wave propagation to not only mitigate the noxious effects created by the hostile medium, but also to utilize it in a constructive manner enabling a huge benefit in communications. We employ time-reversal (T/R) communications to accomplish this task. This project is concerned with the development of secure communications techniques that can operate even in the most extreme conditions while maintaining a secure link between host and client stations. We developed an approach based on the concept of time-reversal (T/R) signal processing. In fact, the development of T/R communication

Fast QC-LDPC code for free space optical communication

Science.gov (United States)

Wang, Jin; Zhang, Qi; Udeh, Chinonso Paschal; Wu, Rangzhong

2017-02-01

Free Space Optical (FSO) Communication systems use the atmosphere as a propagation medium. Hence the atmospheric turbulence effects lead to multiplicative noise related with signal intensity. In order to suppress the signal fading induced by multiplicative noise, we propose a fast Quasi-Cyclic (QC) Low-Density Parity-Check (LDPC) code for FSO Communication systems. As a linear block code based on sparse matrix, the performances of QC-LDPC is extremely near to the Shannon limit. Currently, the studies on LDPC code in FSO Communications is mainly focused on Gauss-channel and Rayleigh-channel, respectively. In this study, the LDPC code design over atmospheric turbulence channel which is nether Gauss-channel nor Rayleigh-channel is closer to the practical situation. Based on the characteristics of atmospheric channel, which is modeled as logarithmic-normal distribution and K-distribution, we designed a special QC-LDPC code, and deduced the log-likelihood ratio (LLR). An irregular QC-LDPC code for fast coding, of which the rates are variable, is proposed in this paper. The proposed code achieves excellent performance of LDPC codes and can present the characteristics of high efficiency in low rate, stable in high rate and less number of iteration. The result of belief propagation (BP) decoding shows that the bit error rate (BER) obviously reduced as the Signal-to-Noise Ratio (SNR) increased. Therefore, the LDPC channel coding technology can effectively improve the performance of FSO. At the same time, the BER, after decoding reduces with the increase of SNR arbitrarily, and not having error limitation platform phenomenon with error rate slowing down.

Automating Deep Space Network scheduling and conflict resolution

Science.gov (United States)

Johnston, Mark D.; Clement, Bradley

2005-01-01

The Deep Space Network (DSN) is a central part of NASA's infrastructure for communicating with active space missions, from earth orbit to beyond the solar system. We describe our recent work in modeling the complexities of user requirements, and then scheduling and resolving conflicts on that basis. We emphasize our innovative use of background 'intelligent' assistants' that carry out search asynchrnously while the user is focusing on various aspects of the schedule.

Space Communications Artificial Intelligence for Link Evaluation Terminal (SCAILET)

Science.gov (United States)

Shahidi, Anoosh

1991-01-01

A software application to assis end-users of the Link Evaluation Terminal (LET) for satellite communication is being developed. This software application incorporates artificial intelligence (AI) techniques and will be deployed as an interface to LET. The high burst rate (HBR) LET provides 30 GHz transmitting/20 GHz receiving, 220/110 Mbps capability for wideband communications technology experiments with the Advanced Communications Technology Satellite (ACTS). The HBR LET and ACTS are being developed at the NASA Lewis Research Center. The HBR LET can monitor and evaluate the integrity of the HBR communications uplink and downlink to the ACTS satellite. The uplink HBR transmission is performed by bursting the bit-pattern as a modulated signal to the satellite. By comparing the transmitted bit pattern with the received bit pattern, HBR LET can determine the bit error rate BER) under various atmospheric conditions. An algorithm for power augmentation is applied to enhance the system's BER performance at reduced signal strength caused by adverse conditions. Programming scripts, defined by the design engineer, set up the HBR LET terminal by programming subsystem devices through IEEE488 interfaces. However, the scripts are difficult to use, require a steep learning curve, are cryptic, and are hard to maintain. The combination of the learning curve and the complexities involved with editing the script files may discourage end-users from utilizing the full capabilities of the HBR LET system. An intelligent assistant component of SCAILET that addresses critical end-user needs in the programming of the HBR LET system as anticipated by its developers is described. A close look is taken at the various steps involved in writing ECM software for a C&P, computer and at how the intelligent assistant improves the HBR LET system and enhances the end-user's ability to perform the experiments.

Distress detection, location, and communications using advanced space technology. [satellite-borne synthetic aperture radar

Science.gov (United States)

Sivertson, W. E., Jr.

1977-01-01

This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

Ultra-fast secure communication with complex systems in classical channels (Conference Presentation)

KAUST Repository

Mazzone, Valerio

2017-04-28

Developing secure communications is a research area of growing interest. During the past years, several cryptographic schemes have been developed, with Quantum cryptography being a promising scheme due to the use of quantum effects, which make very difficult for an eavesdropper to intercept the communication. However, practical quantum key distribution methods have encountered several limitations; current experimental realizations, in fact, fail to scale up on long distances, as well as in providing unconditional security and speed comparable to classical optical communications channels. Here we propose a new, low cost and ultra-fast cryptographic system based on a fully classical optical channel. Our cryptographic scheme exploits the complex synchronization of two different random systems (one on the side of the sender and another on the side of the receiver) to realize a “physical” one paid system. The random medium is created by an optical chip fabricated through electron beam lithography on a Silicon On Insulator (SOI) substrate. We present experiments with ps lasers and commercial fibers, showing the ultrafast distribution of a random key between two users (Alice and Bob), with absolute no possibility for a passive/active eavesdropper to intercept the communication. Remarkably, this system enables the same security of quantum cryptography, but with the use of a classical communication channel. Our system exploits a unique synchronization that exists between two different random systems, and at such is extremely versatile and can enable safe communications among different users in standards telecommunications channels.

Spectral investigation of a complex space charge structure in plasma

International Nuclear Information System (INIS)

Gurlui, S.; Dimitriu, D. G.; Ionita, C.; Schrittwieser, R. W.

2009-01-01

Complex space charge structures bordered by electrical double layers were spectrally investigated in argon plasma in the domain 400-1000 nm, identifying the lines corresponding to the transitions from different excited states of argon. The electron excitation temperature in the argon atoms was estimated from the spectral lines intensity ratio. (authors)

A Summary of - An Earth-to-Deep Space Communications System with Adaptive Tilt and Scintillation Correction Using Near-Earth Relay Mirrors

Science.gov (United States)

Armstrong, J. W.; Yeh, C.; Wilson, K. E.

1998-01-01

Optical telecommunication will be the next technology for wide-band Earth/space communication. Uncompensated propagation through the Earth's atmosphere (e.g., scintillation and wavefront tilt) fundamentally degrade communication to distant spcaecraft.

Effective use of multibeam antenna and space-time multiple access technology in modern mobile communication systems

OpenAIRE

Moskalets, N. V.

2015-01-01

A possibility for efficient use of radio-frequency spectrum and of corresponding increase in productivity of mobile communication system with space-time multiple access obtained by use of multibeam antenna of base station is considered.

Visual Navigation of Complex Information Spaces

Directory of Open Access Journals (Sweden)

Sarah North

1995-11-01

Full Text Available The authors lay the foundation for the introduction of visual navigation aid to assist computer users in direct manipulation of the complex information spaces. By exploring present research on scientific data visualisation and creating a case for improved information visualisation tools, they introduce the design of an improved information visualisation interface utilizing dynamic slider, called Visual-X, incorporating icons with bindable attributes (glyphs. Exploring the improvement that these data visualisations, make to a computing environment, the authors conduct an experiment to compare the performance of subjects who use traditional interfaces and Visual-X. Methodology is presented and conclusions reveal that the use of Visual-X appears to be a promising approach in providing users with a navigation tool that does not overload their cognitive processes.

High Precision Ranging and Range-Rate Measurements over Free-Space-Laser Communication Link

Science.gov (United States)

Yang, Guangning; Lu, Wei; Krainak, Michael; Sun, Xiaoli

2016-01-01

We present a high-precision ranging and range-rate measurement system via an optical-ranging or combined ranging-communication link. A complete bench-top optical communication system was built. It included a ground terminal and a space terminal. Ranging and range rate tests were conducted in two configurations. In the communication configuration with 622 data rate, we achieved a two-way range-rate error of 2 microns/s, or a modified Allan deviation of 9 x 10 (exp -15) with 10 second averaging time. Ranging and range-rate as a function of Bit Error Rate of the communication link is reported. They are not sensitive to the link error rate. In the single-frequency amplitude modulation mode, we report a two-way range rate error of 0.8 microns/s, or a modified Allan deviation of 2.6 x 10 (exp -15) with 10 second averaging time. We identified the major noise sources in the current system as the transmitter modulation injected noise and receiver electronics generated noise. A new improved system will be constructed to further improve the system performance for both operating modes.

Satellite Communications

CERN Document Server

Pelton, Joseph N

2012-01-01

The field of satellite communications represents the world's largest space industry. Those who are interested in space need to understand the fundamentals of satellite communications, its technology, operation, business, economic, and regulatory aspects. This book explains all this along with key insights into the field's future growth trends and current strategic challenges. Fundamentals of Satellite Communications is a concise book that gives all of the key facts and figures as well as a strategic view of where this dynamic industry is going. Author Joseph N. Pelton, PhD, former Dean of the International Space University and former Director of Strategic Policy at Intelstat, presents a r

Impact of communication delays to and from the International Space Station on self-reported individual and team behavior and performance: A mixed-methods study

Science.gov (United States)

Kintz, Natalie M.; Chou, Chih-Ping; Vessey, William B.; Leveton, Lauren B.; Palinkas, Lawrence A.

2016-12-01

Deep space explorations will involve significant delays in communication to and from Earth that will likely impact individual and team outcomes. However, the extent of these impacts and the appropriate countermeasures for their mitigation remain largely unknown. This study utilized the International Space Station (ISS), a high-fidelity analog for deep space, as a research platform to assess the impact of communication delays on individual and team performance, mood, and behavior. Three astronauts on the ISS and 18 mission support personnel performed tasks with and without communication delays (50-s one-way) during a mission lasting 166 days. Self-reported assessments of individual and team performance and mood were obtained after each task. Secondary outcomes included communication quality and task autonomy. Qualitative data from post-mission interviews with astronauts were used to validate and expand on quantitative data, and to elicit recommendations for countermeasures. Crew well-being and communication quality were significantly reduced in communication delay tasks compared to control. Communication delays were also significantly associated with increased individual stress/frustration. Qualitative data suggest communication delays impacted operational outcomes (i.e. task efficiency), teamwork processes (i.e. team/task coordination) and mood (i.e. stress/frustration), particularly when tasks involved high task-related communication demands, either because of poor communication strategies or low crew autonomy. Training, teamwork, and technology-focused countermeasures were identified to mitigate or prevent adverse impacts.

Nonterrestrial material processing and manufacturing of large space systems

Science.gov (United States)

Von Tiesenhausen, G.

1979-01-01

Nonterrestrial processing of materials and manufacturing of large space system components from preprocessed lunar materials at a manufacturing site in space is described. Lunar materials mined and preprocessed at the lunar resource complex will be flown to the space manufacturing facility (SMF), where together with supplementary terrestrial materials, they will be final processed and fabricated into space communication systems, solar cell blankets, radio frequency generators, and electrical equipment. Satellite Power System (SPS) material requirements and lunar material availability and utilization are detailed, and the SMF processing, refining, fabricating facilities, material flow and manpower requirements are described.

Interference Cancellation Using Space-Time Processing and Precoding Design

CERN Document Server

Li, Feng

2013-01-01

Interference Cancellation Using Space-Time Processing and Precoding Design introduces original design methods to achieve interference cancellation, low-complexity decoding and full diversity for a series of multi-user systems. In multi-user environments, co-channel interference will diminish the performance of wireless communications systems. In this book, we investigate how to design robust space-time codes and pre-coders to suppress the co-channel interference when multiple antennas are available.   This book offers a valuable reference work for graduate students, academic researchers and engineers who are interested in interference cancellation in wireless communications. Rigorous performance analysis and various simulation illustrations are included for each design method.   Dr. Feng Li is a scientific researcher at Cornell University.

Creating "communicative spaces": a case of NGO community organizing for HIV/AIDS prevention.

Science.gov (United States)

de Souza, Rebecca

2009-12-01

This study uses the case study method to investigate the processes used by a local nongovernmental organization called the Society for People's Action for Development to organize sex workers in the slums of Bangalore, India, for HIV/AIDS prevention. The nongovernmental organization-facilitated HIV/AIDS program is based on the new paradigm of community organizing that encourages community participation and capacity building. Grounded in the culture-centered approach, this study documents the processes used to organize the women, while highlighting the role of communication in these processes. The study identifies 4 primary processes used to mobilize the community, namely collectivization, community awareness and sensitization, capacity building, and providing legal education and support. Each of these processes highlights the importance of attending to the economic, social, and political realities that shape the health of women. The common thread linking these processes together is the notion of "voice." More specifically, each process serves as a catalyst to produce discursive practices that enable women to provide support to each other, increase awareness in the community about the problems that they face, build self-reliance through financial skills training and communication training, and defend their legal rights. In addition, the study suggests that the primary role of nongovernmental organizations should be the creation of "communicative spaces," which are discursive and material spaces within marginalized communities and mainstream society where cultural participants can identify problems (oftentimes beyond the realm of health), manage solutions to those problems, and advocate for health and social change.

Radioanatomy of the retroperitoneal space.

Science.gov (United States)

Coffin, A; Boulay-Coletta, I; Sebbag-Sfez, D; Zins, M

2015-02-01

The retroperitoneum is a space situated behind the parietal peritoneum and in front of the transversalis fascia. It contains further spaces that are separated by the fasciae, between which communication is possible with both the peritoneal cavity and the pelvis, according to the theory of interfascial spread. The perirenal space has the shape of an inverted cone and contains the kidneys, adrenal glands, and related vasculature. It is delineated by the anterior and posterior renal fasciae, which surround the ureter and allow communication towards the pelvis. At the upper right pole, the perirenal space connects to the retrohepatic space at the bare area of the liver. There is communication between these two spaces through the Kneeland channel. The anterior pararenal space contains the duodenum, pancreas, and the ascending and descending colon. There is free communication within this space, and towards the mesenteries along the vessels. The posterior pararenal space, which contains fat, communicates with the preperitoneal space at the anterior surface of the abdomen between the peritoneum and the transversalis fascia, and allows communication with the contralateral posterior pararenal space. This space follows the length of the ureter to the pelvis, which explains the communication between these areas and the length of the pelvic fasciae. Copyright © 2014 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

EPR and Klein Paradoxes in Complex Hamiltonian Dynamics and Krein Space Quantization

International Nuclear Information System (INIS)

Payandeh, Farrin

2015-01-01

Negative energy states are applied in Krein space quantization approach to achieve a naturally renormalized theory. For example, this theory by taking the full set of Dirac solutions, could be able to remove the propagator Green function's divergences and automatically without any normal ordering, to vanish the expected value for vacuum state energy. However, since it is a purely mathematical theory, the results are under debate and some efforts are devoted to include more physics in the concept. Whereas Krein quantization is a pure mathematical approach, complex quantum Hamiltonian dynamics is based on strong foundations of Hamilton-Jacobi (H-J) equations and therefore on classical dynamics. Based on complex quantum Hamilton-Jacobi theory, complex spacetime is a natural consequence of including quantum effects in the relativistic mechanics, and is a bridge connecting the causality in special relativity and the non-locality in quantum mechanics, i.e. extending special relativity to the complex domain leads to relativistic quantum mechanics. So that, considering both relativistic and quantum effects, the Klein-Gordon equation could be derived as a special form of the Hamilton-Jacobi equation. Characterizing the complex time involved in an entangled energy state and writing the general form of energy considering quantum potential, two sets of positive and negative energies will be realized. The new states enable us to study the spacetime in a relativistic entangled “space-time” state leading to 12 extra wave functions than the four solutions of Dirac equation for a free particle. Arguing the entanglement of particle and antiparticle leads to a contradiction with experiments. So, in order to correct the results, along with a previous investigation [1], we realize particles and antiparticles as physical entities with positive energy instead of considering antiparticles with negative energy. As an application of modified descriptions for entangled (space

Soil Heavy Metal Concentrations in Green Space of Mobarake Steel Complex

Directory of Open Access Journals (Sweden)

vahid Moradinasab

2017-01-01

Full Text Available Introduction: Water shortage in arid and semiarid regions of the world is a cause of serious concerns. The severe water scarcity urges the reuse of treated wastewater effluent and marginal water as a resource for irrigation. Mobarake Steel Complex has been using treated industrial wastewater for drip-irrigation of trees in about 1350 ha of its green space. However, wastewater may contain some amounts of toxic heavy metals, which create problems. Excessive accumulation of heavy metals in agricultural soils through wastewater irrigation may not only result in soil contamination, but also affect food quality and safety. Improper irrigation management, however, can lead to the loss of soil quality through such processes as contamination and salination. Soil quality implies its capacity to sustain biological productivity, maintain environmental quality, and enhance plants, human and animal health. Soil quality assessment is a tool that helps managers to evaluate short-term soil problems and appropriate management strategies for maintaining soil quality in the long time. Mobarakeh Steel Complex has been using treated wastewater for irrigation of green space to combat water shortage and prevent environmental pollution. This study was performed to assess the impact of short- middle, and long-term wastewater irrigation on soil heavy metal concentration in green space of Mobarake Steel complex. Materials and Methods: The impacts of wastewater irrigation on bioavailable and total heavy metal concentrations in the soils irrigated with treated wastewater for 2, 6 and 18 years as compared to those in soils irrigated with groundwater and un-irrigated soils. Soils were sampled from the wet bulb produced by under-tree sprinklers in three depths (0-20, 20-40 and 40-60 cm. Soil samples were air-dried, and crushed to pass through a 2-mm sieve. Plant-available metal concentrations were extracted from the soil with diethylenetriaminepentaacetic acid-CaCl2

Detecting binary non-return-to-zero data in free-space optical communication systems using FPGAs

Science.gov (United States)

Bui, Vy; Tran, Lan; El-Araby, Esam; Namazi, Nader M.

2014-06-01

High bandwidth, fast deployment with relatively low cost implementation are some of the important advantages of free space optical (FSO) communications. However, the atmospheric turbulence has a substantial impact on the quality of a laser beam propagating through the atmosphere. A new method was presented in [1] and [2] to perform bit synchronization and detection of binary Non-Return-to-Zero (NRZ) data from a free-space optical (FSO) communication link. It was shown that, when the data is binary NRZ with no modulation, the Haar wavelet transformation can effectively reduce the scintillation noise. In this paper, we leverage and modify the work presented in [1] in order to provide a real-time streaming hardware prototype. The applicability of these concepts will be demonstrated through providing the hardware prototype using one of the state-of-the-art reconfigurable hardware, namely Field Programmable Gate Arrays, and highly productive high-level design tools such as System Generator for DSP from Xilinx.

BER Analysis of Coherent Free-Space Optical Communication Systems with a Focal-Plane-Based Wavefront Sensor

Science.gov (United States)

Cao, Jingtai; Zhao, Xiaohui; Liu, Wei; Gu, Haijun

2018-03-01

A wavefront sensor is one of most important units for an adaptive optics system. Based on our previous works, in this paper, we discuss the bit-error-rate (BER) performance of coherent free space optical communication systems with a focal-plane-based wavefront sensor. Firstly, the theory of a focal-plane-based wavefront sensor is given. Then the relationship between the BER and the mixing efficiency with a homodyne receiver is discussed on the basis of binary-phase-shift-keying (BPSK) modulation. Finally, the numerical simulation results are shown that the BER will be decreased obviously after aberrations correction with the focal-plane-based wavefront sensor. In addition, the BER will decrease along with increasing number of photons received within a single bit. These analysis results will provide a reference for the design of the coherent Free space optical communication (FSOC) system.

Space Network Devices Developed

Science.gov (United States)

Jones, Robert E.

2004-01-01

The NASA Glenn Research Center through a contract with Spectrum Astro, Inc., has been developing space network hardware as an enabling technology using open systems interconnect (OSI) standards for space-based communications applications. The OSI standard is a well-recognized layered reference model that specifies how data should be sent node to node in a communications network. Because of this research and technology development, a space-qualifiable Ethernet-based network interface card (similar to the type found in a networked personal computer) and the associated four-port hub were designed and developed to flight specifications. During this research and development, there also have been many lessons learned for determining approaches for migrating existing spacecraft architectures to an OSI-network-based platform. Industry has recognized the benefits of targeting hardware developed around OSI standards such as Transmission Control Protocol/Internet Protocol (TCP/IP) or similar protocols for use in future generations of space communication systems. Some of these tangible benefits include overall reductions in mission schedule and cost and in system complexity. This development also brings us a step closer to the realization of a principal investigator on a terrestrial Internet site being able to interact with space platform assets in near real time. To develop this hardware, Spectrum Astro first conducted a technology analysis of alternatives study. For this analysis, they looked at the features of three protocol specifications: Ethernet (IEEE 802.3), Firewire (IEEE 1394), and Spacewire (IEEE 1355). A thorough analysis was performed on the basis of criteria such as current protocol performance and suitability for future space applications. Spectrum Astro also projected future influences such as cost, hardware and software availability, throughput performance, and integration procedures for current and transitive space architectures. After a thorough analysis

Colorings of simplicial complexes and vector bundles over Davis-Januszkiewicz spaces

NARCIS (Netherlands)

Notbohm, D.R.A.W.

2010-01-01

We show that coloring properties of a simplicial complex K are reflected by splitting properties of a bundle over the associated Davis-Januszkiewicz space whose Chern classes are given by the elementary symmetric polynomials in the generators of the Stanley-Reisner algebra of K. © 2009 The

Expert-guided evolutionary algorithm for layout design of complex space stations

Science.gov (United States)

Qian, Zhiqin; Bi, Zhuming; Cao, Qun; Ju, Weiguo; Teng, Hongfei; Zheng, Yang; Zheng, Siyu

2017-08-01

The layout of a space station should be designed in such a way that different equipment and instruments are placed for the station as a whole to achieve the best overall performance. The station layout design is a typical nondeterministic polynomial problem. In particular, how to manage the design complexity to achieve an acceptable solution within a reasonable timeframe poses a great challenge. In this article, a new evolutionary algorithm has been proposed to meet such a challenge. It is called as the expert-guided evolutionary algorithm with a tree-like structure decomposition (EGEA-TSD). Two innovations in EGEA-TSD are (i) to deal with the design complexity, the entire design space is divided into subspaces with a tree-like structure; it reduces the computation and facilitates experts' involvement in the solving process. (ii) A human-intervention interface is developed to allow experts' involvement in avoiding local optimums and accelerating convergence. To validate the proposed algorithm, the layout design of one-space station is formulated as a multi-disciplinary design problem, the developed algorithm is programmed and executed, and the result is compared with those from other two algorithms; it has illustrated the superior performance of the proposed EGEA-TSD.

A Common Communications, Navigation and Surveillance Infrastructure for Accommodating Space Vehicles in the Next Generation Air Transportation System

Science.gov (United States)

VanSuetendael, RIchard; Hayes, Alan; Birr, Richard

2008-01-01

Suborbital space flight and space tourism are new potential markets that could significantly impact the National Airspace System (NAS). Numerous private companies are developing space flight capabilities to capture a piece of an emerging commercial space transportation market. These entrepreneurs share a common vision that sees commercial space flight as a profitable venture. Additionally, U.S. space exploration policy and national defense will impose significant additional demands on the NAS. Air traffic service providers must allow all users fair access to limited airspace, while ensuring that the highest levels of safety, security, and efficiency are maintained. The FAA's Next Generation Air Transportation System (NextGen) will need to accommodate spacecraft transitioning to and from space through the NAS. To accomplish this, space and air traffic operations will need to be seamlessly integrated under some common communications, navigation and surveillance (CNS) infrastructure. As part of NextGen, the FAA has been developing the Automatic Dependent Surveillance Broadcast (ADS-B) which utilizes the Global Positioning System (GPS) to track and separate aircraft. Another key component of NextGen, System-Wide Information Management/ Network Enabled Operations (SWIM/NEO), is an open architecture network that will provide NAS data to various customers, system tools and applications. NASA and DoD are currently developing a space-based range (SBR) concept that also utilizes GPS, communications satellites and other CNS assets. The future SBR will have very similar utility for space operations as ADS-B and SWIM has for air traffic. Perhaps the FAA, NASA, and DoD should consider developing a common space-based CNS infrastructure to support both aviation and space transportation operations. This paper suggests specific areas of research for developing a CNS infrastructure that can accommodate spacecraft and other new types of vehicles as an integrated part of NextGen.

Modeling the Internet of Things, Self-Organizing and Other Complex Adaptive Communication Networks: A Cognitive Agent-Based Computing Approach.

Directory of Open Access Journals (Sweden)

Samreen Laghari

Full Text Available Computer Networks have a tendency to grow at an unprecedented scale. Modern networks involve not only computers but also a wide variety of other interconnected devices ranging from mobile phones to other household items fitted with sensors. This vision of the "Internet of Things" (IoT implies an inherent difficulty in modeling problems.It is practically impossible to implement and test all scenarios for large-scale and complex adaptive communication networks as part of Complex Adaptive Communication Networks and Environments (CACOONS. The goal of this study is to explore the use of Agent-based Modeling as part of the Cognitive Agent-based Computing (CABC framework to model a Complex communication network problem.We use Exploratory Agent-based Modeling (EABM, as part of the CABC framework, to develop an autonomous multi-agent architecture for managing carbon footprint in a corporate network. To evaluate the application of complexity in practical scenarios, we have also introduced a company-defined computer usage policy.The conducted experiments demonstrated two important results: Primarily CABC-based modeling approach such as using Agent-based Modeling can be an effective approach to modeling complex problems in the domain of IoT. Secondly, the specific problem of managing the Carbon footprint can be solved using a multiagent system approach.

Modeling the Internet of Things, Self-Organizing and Other Complex Adaptive Communication Networks: A Cognitive Agent-Based Computing Approach.

Science.gov (United States)

Laghari, Samreen; Niazi, Muaz A

2016-01-01

Computer Networks have a tendency to grow at an unprecedented scale. Modern networks involve not only computers but also a wide variety of other interconnected devices ranging from mobile phones to other household items fitted with sensors. This vision of the "Internet of Things" (IoT) implies an inherent difficulty in modeling problems. It is practically impossible to implement and test all scenarios for large-scale and complex adaptive communication networks as part of Complex Adaptive Communication Networks and Environments (CACOONS). The goal of this study is to explore the use of Agent-based Modeling as part of the Cognitive Agent-based Computing (CABC) framework to model a Complex communication network problem. We use Exploratory Agent-based Modeling (EABM), as part of the CABC framework, to develop an autonomous multi-agent architecture for managing carbon footprint in a corporate network. To evaluate the application of complexity in practical scenarios, we have also introduced a company-defined computer usage policy. The conducted experiments demonstrated two important results: Primarily CABC-based modeling approach such as using Agent-based Modeling can be an effective approach to modeling complex problems in the domain of IoT. Secondly, the specific problem of managing the Carbon footprint can be solved using a multiagent system approach.

Moving Toward Space Internetworking via DTN: Its Operational Challenges, Benefits, and Management

Science.gov (United States)

Barkley, Erik; Burleigh, Scott; Gladden, Roy; Malhotra, Shan; Shames, Peter

2010-01-01

The international space community has begun to recognize that the established model for management of communications with spacecraft - commanded data transmission over individual pair-wise contacts - is operationally unwieldy and will not scale in support of increasingly complex and sophisticated missions such as NASA's Constellation project. Accordingly, the international Inter-Agency Operations Advisory Group (IOAG) ichartered a Space Internetworking Strategy Group (SISG), which released its initial recommendations in a November 2008 report. The report includes a recommendation that the space flight community adopt Delay-Tolerant Networking (DTN) to address the problem of interoperability and communication scaling, especially in mission environments where there are multiple spacecraft operating in concert. This paper explores some of the issues that must be addressed in implementing, deploying, and operating DTN as part of a multi-mission, multi-agency space internetwork as well as benefits and future operational scenarios afforded by DTN-based space internetworking.

Is long distance free space quantum communication with the OAM state of light feasible [Presentation

CSIR Research Space (South Africa)

Hamadou Ibrahim, A

2013-06-01

Full Text Available -space quantum communication with the OAM state of light feasible? A. HAMADOU IBRAHIM1,2, F.S. ROUX1, M. McLAREN1,3 , A. FORBES1,2,3 & T. KONRAD2 1. CSIR National Laser Centre, PO Box 395, Pretoria 0001 2. School of Physics, University of Kwazulu...

Polarization tracking system for free-space optical communication, including quantum communication

Science.gov (United States)

Nordholt, Jane Elizabeth; Newell, Raymond Thorson; Peterson, Charles Glen; Hughes, Richard John

2018-01-09

Quantum communication transmitters include beacon lasers that transmit a beacon optical signal in a predetermined state of polarization such as one of the states of polarization of a quantum communication basis. Changes in the beacon polarization are detected at a receiver, and a retarder is adjusted so that the states of polarization in a received quantum communication optical signal are matched to basis polarizations. The beacon and QC signals can be at different wavelengths so that the beacon does not interfere with detection and decoding of the QC optical signal.

Fixed point theorems in complex valued metric spaces

Directory of Open Access Journals (Sweden)

Naval Singh

2016-07-01

Full Text Available The aim of this paper is to establish and prove several results on common fixed point for a pair of mappings satisfying more general contraction conditions portrayed by rational expressions having point-dependent control functions as coefficients in complex valued metric spaces. Our results generalize and extend the results of Azam et al. (2011 [1], Sintunavarat and Kumam (2012 [2], Rouzkard and Imdad (2012 [3], Sitthikul and Saejung (2012 [4] and Dass and Gupta (1975 [5]. To substantiate the authenticity of our results and to distinguish them from existing ones, some illustrative examples are also furnished.

The Virtual Table: A Framework for Online Teamwork, Collaboration, and Communication.

Science.gov (United States)

Endersby, Lisa; Phelps, Kirstin; Jenkins, Dan

2017-03-01

This chapter reviews the complex relationship between technology and leadership, focusing on how technology affects the development and demonstration of skills in communication, teamwork, and collaboration. The chapter also proposes a framework for identifying and assessing key leadership competencies in the digital space. © 2017 Wiley Periodicals, Inc., A Wiley Company.

Japan's telecommunications - New initiatives in space communications

Science.gov (United States)

Iida, T.

1992-04-01

Despite recent advances in optical transmission technology, intensive R&D work in the field of satellite communications is now being undertaken in Japan. It is believed that satellites offer advantages in several important areas, including wide coverage broadcasting, immediacy of service, suitability for the implementation of HDTV, and advantages in disaster communications and other social services. Here, some experimental projects in the field of satellite communications planned in Japan for the 1990s are summarized. In particular, attention is given to broadcast satellite development, intersatellite links, advanced mobile communication concepts, large antenna assembly experiment, small satellite R&D, and Pan-Pacific information network experiment.

Space mining and its regulation

CERN Document Server

Jakhu, Ram S; Nyampong, Yaw Otu Mankata

2017-01-01

This book addresses the complex technical challenges presented by remote space mining in terms of robotics, remote power systems, space transport, IT and communications systems, and more. It also addresses the difficult oversight and regulatory issues that face states and non-state enterprises that would take on the perilous task of obtaining natural resources from the Moon and asteroids. An increasing number of countries are becoming involved in space-related activities that were previously carried out primarily by the United States and the USSR (now the Russian Federation). How these regulatory endeavors might be handled in international treaties, standards, codes of conduct or other means have become a truly international political issue. And there is yet another issue. In the past, space activities traditionally fell under the exclusive domain of government. But the last few years have seen the emergence of the private sector of "space entrepreneurs." This poses many challenges for the pre-existing govern...

Public communication on times of environmental crisis. The opening of San Rafael 's uranium complex

International Nuclear Information System (INIS)

Calvino, Carlos; Cisneros, Martin

2008-01-01

Full text: Argentina has had a lot of cultural changes in the last few years. An environmental movement has gathered and is trying to stop the opening of the Sierra Pintada uranium complex, near the city of San Rafael, in the south of Mendoza province. Since 2005, several 'groundless information' have been published in the local media about the dangers of this re-opening. These news exaggerate the properties of radon gas, claiming that it will reach San Rafael city (20 miles from the complex), rising radiological risk among the population, etc. This scene shows a 'non-real' picture of the regulatory activities that the Nuclear Regulatory Authority (ARN), a government agency that regulates nuclear facilities in Argentina, is really and systematically accomplishing. In this situation, the board of Directors of ARN decided to entrust a full analysis of the environmental issue in the area. The Office of Press and Communication implemented a local communication plan, using a Strategic and Systemic tool kit. The period to be analyzed is from second semester 2005 to February 2007. A little bit of history: the San Rafael Complex started in September 20 of 1979. It belongs to the National Commission of Atomic Energy (CNEA), a government agency. Until its temporary suspension in 1995 for international market reasons (uranium price was U$S 10 / pound), almost 2 million tons of uranium were processed. Besides its temporary suspension, the ARN has been constantly monitoring this particular former complex. In the year 2001, CNEA notices that the uranium price starts to rise and entrust National Technology University, Avellaneda Branch, to accomplish an Environmental Impact Report, according to the argentine law 25.585. Due especially to the rising of uranium price, (actually, the uranium price is approximately U$S 200) the national government determined to restart the extraction of the mineral again. By the year 2004, with the results of the Environmental Impact report, CNEA

Quantum trajectories in complex space: One-dimensional stationary scattering problems

International Nuclear Information System (INIS)

Chou, C.-C.; Wyatt, Robert E.

2008-01-01

One-dimensional time-independent scattering problems are investigated in the framework of the quantum Hamilton-Jacobi formalism. The equation for the local approximate quantum trajectories near the stagnation point of the quantum momentum function is derived, and the first derivative of the quantum momentum function is related to the local structure of quantum trajectories. Exact complex quantum trajectories are determined for two examples by numerically integrating the equations of motion. For the soft potential step, some particles penetrate into the nonclassical region, and then turn back to the reflection region. For the barrier scattering problem, quantum trajectories may spiral into the attractors or from the repellers in the barrier region. Although the classical potentials extended to complex space show different pole structures for each problem, the quantum potentials present the same second-order pole structure in the reflection region. This paper not only analyzes complex quantum trajectories and the total potentials for these examples but also demonstrates general properties and similar structures of the complex quantum trajectories and the quantum potentials for one-dimensional time-independent scattering problems

On the performance of free-space optical communication systems with multiuser diversity

KAUST Repository

Yang, Liang

2014-09-01

Free space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over weak atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, and coverage are analyzed.

Tactile Communications

Data.gov (United States)

National Aeronautics and Space Administration — Communication with the crew is vital and must be maintained regardless of environmental conditions and crew activity. Current spacecraft communication systems depend...

Demonstration of free-space optical communication for long-range data links between balloons on Project Loon

Science.gov (United States)

Moision, Bruce; Erkmen, Baris; Keyes, Edward; Belt, Todd; Bowen, Oliver; Brinkley, Devin; Csonka, Paul; Eglington, Michael; Kazmierski, Andrei; Kim, Nam-hyong; Moody, John; Tu, Thanh; Vermeer, William

2017-02-01

Internet connectivity is limited and in some cases non-existent for a significant part of the world's population. Project Loon aims to address this with a network of high-altitude balloons traveling in the stratosphere, at an altitude of approximately 20 km. The balloons navigate by using the stratified wind layers at different altitudes, adjusting the balloon's altitude to catch winds in a desired direction. Data transfer is achieved by 1) uplinking a signal from an Internet-connected ground station to a balloon terminal, 2) crosslinking the signal through the balloon network to reach the geographic area of the users, and 3) downlinking the signal directly to the end-users' phones or other LTE-enabled devices. We describe Loon's progress on utilizing free-space optical communications (FSOC) for the inter-balloon crosslinks. FSOC, offering high data rates and long communication ranges, is well-suited for communication between high-altitude platforms. A stratospheric link is sufficiently high to be above weather events (clouds, fog, rain, etc.), and the impact of atmospheric turbulence is significantly weaker than at ground level. In addition, being in the stratosphere as opposed to space helps avoid the typical challenges faced by space-based systems, namely operation in a vacuum environment with significant radiation. Finally, the angular pointing disturbances introduced by a floating balloon-based platform are notably less than any propelled platform, which simplifies the disturbance rejection requirements on the FSOC system. We summarize results from Project Loon's early-phase experimental inter-balloon links at 20 km altitude, demonstrating full duplex 130 Mbps throughput at distances in excess of 100 km over the course of several-day flights. The terminals utilize a monostatic design, with dual wavelengths for communication and a dedicated wide-angle beacon for pointing, acquisition, and tracking. We summarize the constraints on the terminal design, and the

Precoded generalized space shift keying for indoor visible light communications

KAUST Repository

Kadampot, Ishaque Ashar

2014-09-01

We consider a visible light communication system with 2 transmit light emitting diodes (LED) and nr receive photodiodes. An optical generalized space shift keying modulation scheme is considered for the transmission of bits where each LED can be either in ON state or OFF state at a given time. With this set-up, we design in this paper a precoder for this modulation scheme given the channel state information to improve the bit error rate performance of the system. As conventional precoding techniques for radio frequency at the transmitter cannot be applied to the optical intensity channel, we formulate an optimization problem with constraints for this specific channel. An analytical solution for the precoder is derived and the system performance is compared with and without precoder.

System and method that suppresses intensity fluctuations for free space high-speed optical communication

Science.gov (United States)

Berman, Gennady P [Los Alamos, NM; Bishop, Alan R [Los Alamos, NM; Nguyen, Dinh C [Los Alamos, NM; Chernobrod, Boris M [Santa Fe, NM; Gorshkov, Vacheslav N [Kiev, UA

2009-10-13

A high-speed (Gbps), free space optical communication system is based on spectral encoding of radiation from a wide band light source, such as a laser. By using partially coherent laser beams in combination with a relatively slow photosensor, scintillations can be suppressed by orders of magnitude for distances of more than 10 km. To suppress the intensity fluctuations due to atmospheric turbulence, a source with partial transverse coherence in combination with slow response time photodetector is used. Information is encoded in the spectral domain of a wideband optical source by modulation of spectral amplitudes. A non-coherent light source with wide spectrum (an LED, for example) may be used for high-speed communication over short (less than about a mile) distances.

User evaluations of design complexity: the impact of visual perceptions for effective online health communication.

Science.gov (United States)

Lazard, Allison; Mackert, Michael

2014-10-01

This paper highlights the influential role of design complexity for users' first impressions of health websites. An experimental design was utilized to investigate whether a website's level of design complexity impacts user evaluations. An online questionnaire measured the hypothesized impact of design complexity on predictors of message effectiveness. Findings reveal that increased design complexity was positively associated with higher levels of perceived design esthetics, attitude toward the website, perceived message comprehensibility, perceived ease of use, perceived usefulness, perceived message quality, perceived informativeness, and perceived visual informativeness. This research gives further evidence that design complexity should be considered an influential variable for health communicators to effectively reach their audiences, as it embodies the critical first step for message evaluation via electronic platforms. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Data transmission with twisted light through a free-space to fiber optical communication link

International Nuclear Information System (INIS)

Brüning, Robert; Duparré, Michael; Ndagano, Bienvenu; McLaren, Melanie; Forbes, Andrew; Schröter, Siegmund; Kobelke, Jens

2016-01-01

Mode division multiplexing (MDM), where information is transmitted in the spatial modes of light, is mooted as a future technology with which to transmit large bits of information. However, one of the key issues in optical communication lies in connecting free-space to optical fiber networks, otherwise known as the ‘last mile’ problem. This is particularly problematic for MDM as the eigenmodes of free-space and fibers are in general not the same. Here we demonstrate a data transmission scheme across a free-space and fiber link using twisted light in the form of Laguerre–Gaussian (LG) azimuthal modes. As a proof-of-principle we design and implement a custom fiber where the supported LG modes can be grouped into five non-degenerate sets, and successfully transmit a gray-scale image across the composite link using one mode from each group, thereby ensuring minimal crosstalk. (letter)

12.5 Gb/s multi-channel broadcasting transmission for free-space optical communication based on the optical frequency comb module.

Science.gov (United States)

Tan, Jun; Zhao, Zeping; Wang, Yuehui; Zhang, Zhike; Liu, Jianguo; Zhu, Ninghua

2018-01-22

A wide-spectrum, ultra-stable optical frequency comb (OFC) module with 100 GHz frequency intervals based on a quantum dot mode locked (QDML) laser is fabricated by our lab, and a scheme with 12.5 Gb/s multi-channel broadcasting transmission for free-space optical (FSO) communication is proposed based on the OFC module. The output power of the OFC is very stable, with the specially designed circuit and the flatness of the frequency comb over the span of 6 nm, which can be limited to 1.5 dB. Four channel wavelengths are chosen to demonstrate one-to-many channels for FSO communication, like optical wireless broadcast. The outdoor experiment is established to test the bit error rate (BER) and eye diagrams with 12.5 Gb/s on-off keying (OOK). The indoor experiment is used to test the highest traffic rate, which is up to 21 Gb/s for one-hop FSO communication. To the best of our knowledge, this scheme is the first to propose the realization of one-to-many broadcasting transmission for FSO communication based on the OFC module. The advantages of integration, miniaturization, channelization, low power consumption, and unlimited bandwidth of one-to-many broadcasting communication scheme, shows promising results on constructing the future space-air-ground-ocean (SAGO) FSO communication networks.

Employers' experience of employees with cancer: trajectories of complex communication.

Science.gov (United States)

Tiedtke, C M; Dierckx de Casterlé, B; Frings-Dresen, M H W; De Boer, A G E M; Greidanus, M A; Tamminga, S J; De Rijk, A E

2017-10-01

Remaining in paid work is of great importance for cancer survivors, and employers play a crucial role in achieving this. Return to work (RTW) is best seen as a process. This study aims to provide insight into (1) Dutch employers' experiences with RTW of employees with cancer and (2) the employers' needs for support regarding this process. Thirty employer representatives of medium and large for-profit and non-profit organizations were interviewed to investigate their experiences and needs in relation to employees with cancer. A Grounded Theory approach was used. We revealed a trajectory of complex communication and decision-making during different stages, from the moment the employee disclosed that they had been diagnosed to the period after RTW, permanent disability, or the employee's passing away. Employers found this process demanding due to various dilemmas. Dealing with an unfavorable diagnosis and balancing both the employer's and the employee's interests were found to be challenging. Two types of approach to support RTW of employees with cancer were distinguished: (1) a business-oriented approach and (2) a care-oriented approach. Differences in approach were related to differences in organizational structure and employer and employee characteristics. Employers expressed a need for communication skills, information, and decision-making skills to support employees with cancer. The employers interviewed stated that dealing with an employee with cancer is demanding and that the extensive Dutch legislation on RTW did not offer all the support needed. We recommend providing them with easily accessible information on communication and leadership training to better support employees with cancer. • Supporting employers by training communication and decision-making skills and providing information on cancer will contribute to improving RTW support for employees with cancer. • Knowing that the employer will usually be empathic when an employee reveals that they have

Investigating the Experiential Impact of Sensory Affect in Contemporary Communication Design Studio Education

Science.gov (United States)

Marshalsey, Lorraine

2015-01-01

The studio is the primary site for learning in specialist Communication Design education worldwide. Differing higher education institutions, including art schools and university campuses, have developed a varied range of studio environments. These diverse learning spaces inherently create a complex fabric of affects. In addition, Communication…

Free-Space Optical Communications Link at 1550-nm using Multiple-Quantum-Well Modulating Retroreflectors in a Marine Environment

National Research Council Canada - National Science Library

Rabinovich, W. S; Mahon, R; Burris, H. R; Gilbreath, G. C; Goetz, P. G; Moore, C. I; Stell, M. F; Vilcheck, M. J; Witkowsky, J. L; Swingen, L

2005-01-01

A 1550-nm eye-safe, free-space optical communications link is demonstrated at rates up to 5 Mbits/s over a distance of 2 km in the Chesapeake Bay, using quantum-well-based modulating retroreflectors...

Reality and dimension of space and the complexity of quantum mechanics

International Nuclear Information System (INIS)

Mirman, R.

1988-01-01

The dimension (and signature) of space is a result of distances being real numbers and quantum mechanical state functions being complex ones; it is an inescapable consequence of quantum mechanics and group theory. So nonrelativistic quantum mechanics cannot be complete (it requires ad hoc additional assumptions) and consistent (nor can classical physics), leading to relativity, quantum mechanics, and field theory. Implications of the constraints of consistency and physical reasonableness and of group theory for the structure of these theories are considered. It appears that there are simple, perhaps unavoidable reasons for the laws of physics, the nature of the world they describe, and the space in which they act

Topological Rankings in Communication Networks

DEFF Research Database (Denmark)

Aabrandt, Andreas; Hansen, Vagn Lundsgaard; Træholt, Chresten

2015-01-01

In the theory of communication the central problem is to study how agents exchange information. This problem may be studied using the theory of connected spaces in topology, since a communication network can be modelled as a topological space such that agents can communicate if and only...... if they belong to the same path connected component of that space. In order to study combinatorial properties of such a communication network, notions from algebraic topology are applied. This makes it possible to determine the shape of a network by concrete invariants, e.g. the number of connected components...

Advanced Autonomous Systems for Space Operations

Science.gov (United States)

Gross, A. R.; Smith, B. D.; Muscettola, N.; Barrett, A.; Mjolssness, E.; Clancy, D. J.

2002-01-01

New missions of exploration and space operations will require unprecedented levels of autonomy to successfully accomplish their objectives. Inherently high levels of complexity, cost, and communication distances will preclude the degree of human involvement common to current and previous space flight missions. With exponentially increasing capabilities of computer hardware and software, including networks and communication systems, a new balance of work is being developed between humans and machines. This new balance holds the promise of not only meeting the greatly increased space exploration requirements, but simultaneously dramatically reducing the design, development, test, and operating costs. New information technologies, which take advantage of knowledge-based software, model-based reasoning, and high performance computer systems, will enable the development of a new generation of design and development tools, schedulers, and vehicle and system health management capabilities. Such tools will provide a degree of machine intelligence and associated autonomy that has previously been unavailable. These capabilities are critical to the future of advanced space operations, since the science and operational requirements specified by such missions, as well as the budgetary constraints will limit the current practice of monitoring and controlling missions by a standing army of ground-based controllers. System autonomy capabilities have made great strides in recent years, for both ground and space flight applications. Autonomous systems have flown on advanced spacecraft, providing new levels of spacecraft capability and mission safety. Such on-board systems operate by utilizing model-based reasoning that provides the capability to work from high-level mission goals, while deriving the detailed system commands internally, rather than having to have such commands transmitted from Earth. This enables missions of such complexity and communication` distances as are not

Internet Technology for Future Space Missions

Science.gov (United States)

Hennessy, Joseph F. (Technical Monitor); Rash, James; Casasanta, Ralph; Hogie, Keith

2002-01-01

Ongoing work at National Aeronautics and Space Administration Goddard Space Flight Center (NASA/GSFC), seeks to apply standard Internet applications and protocols to meet the technology challenge of future satellite missions. Internet protocols and technologies are under study as a future means to provide seamless dynamic communication among heterogeneous instruments, spacecraft, ground stations, constellations of spacecraft, and science investigators. The primary objective is to design and demonstrate in the laboratory the automated end-to-end transport of files in a simulated dynamic space environment using off-the-shelf, low-cost, commodity-level standard applications and protocols. The demonstrated functions and capabilities will become increasingly significant in the years to come as both earth and space science missions fly more sensors and the present labor-intensive, mission-specific techniques for processing and routing data become prohibitively. This paper describes how an IP-based communication architecture can support all existing operations concepts and how it will enable some new and complex communication and science concepts. The authors identify specific end-to-end data flows from the instruments to the control centers and scientists, and then describe how each data flow can be supported using standard Internet protocols and applications. The scenarios include normal data downlink and command uplink as well as recovery scenarios for both onboard and ground failures. The scenarios are based on an Earth orbiting spacecraft with downlink data rates from 300 Kbps to 4 Mbps. Included examples are based on designs currently being investigated for potential use by the Global Precipitation Measurement (GPM) mission.

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...

On projective synchronization of hyperchaotic complex nonlinear systems based on passive theory for secure communications

International Nuclear Information System (INIS)

Mahmoud, Gamal M; Mahmoud, Emad E; Arafa, Ayman A

2013-01-01

In this paper we deal with the projective synchronization (PS) of hyperchaotic complex nonlinear systems and its application in secure communications based on passive theory. The unpredictability of the scaling factor in PS can additionally enhance the security of communications. In this paper, a scheme for secure message transmission is proposed, and we try to transmit more than one large or bounded message from the transmitter to the receiver. The new hyperchaotic complex Lorenz system is employed to encrypt these messages. In the transmitter, the original messages are modulated into its parameter. In the receiver, we assume that the parameter of the receiver system is uncertain. The controllers and corresponding parameter update law are constructed to achieve PS between the transmitter and receiver system with an uncertain parameter, and identify the unknown parameter via passive theory. The original messages can be recovered successfully through some simple operations by the estimated parameter. Numerical results have verified the effectiveness and feasibility of the presented method. (paper)

On the average complexity of sphere decoding in lattice space-time coded multiple-input multiple-output channel

KAUST Repository

Abediseid, Walid

2012-01-01

complexity of sphere decoding for the quasi- static, lattice space-time (LAST) coded MIMO channel. Specifically, we drive an upper bound of the tail distribution of the decoder's computational complexity. We show that when the computational complexity exceeds

Assured communications and combat resiliency: the relationship between effective national communications and combat efficiency

Science.gov (United States)

Allgood, Glenn O.; Kuruganti, Phani Teja; Nutaro, James; Saffold, Jay

2009-05-01

Combat resiliency is the ability of a commander to prosecute, control, and consolidate his/her's sphere of influence in adverse and changing conditions. To support this, an infrastructure must exist that allows the commander to view the world in varying degrees of granularity with sufficient levels of detail to permit confidence estimates to be levied against decisions and course of actions. An infrastructure such as this will include the ability to effectively communicate context and relevance within and across the battle space. To achieve this will require careful thought, planning, and understanding of a network and its capacity limitations in post-event command and control. Relevance and impact on any existing infrastructure must be fully understood prior to deployment to exploit the system's full capacity and capabilities. In this view, the combat communication network is considered an integral part of or National communication network and infrastructure. This paper will describe an analytical tool set developed at ORNL and RNI incorporating complexity theory, advanced communications modeling, simulation, and visualization technologies that could be used as a pre-planning tool or post event reasoning application to support response and containment.

Recent advances in high-capacity free-space optical and radio-frequency communications using orbital angular momentum multiplexing

Science.gov (United States)

Ren, Yongxiong; Xie, Guodong; Yan, Yan; Li, Long; Zhao, Zhe; Wang, Jian; Tur, Moshe; Molisch, Andreas F.; Ashrafi, Solyman

2017-01-01

There is a continuing growth in the demand for data bandwidth, and the multiplexing of multiple independent data streams has the potential to provide the needed data capacity. One technique uses the spatial domain of an electromagnetic (EM) wave, and space division multiplexing (SDM) has become increasingly important for increased transmission capacity and spectral efficiency of a communication system. A subset of SDM is mode division multiplexing (MDM), in which multiple orthogonal beams each on a different mode can be multiplexed. A potential modal basis set to achieve MDM is to use orbital angular momentum (OAM) of EM waves. In such a system, multiple OAM beams each carrying an independent data stream are multiplexed at the transmitter, propagate through a common medium and are demultiplexed at the receiver. As a result, the total capacity and spectral efficiency of the communication system can be multiplied by a factor equal to the number of transmitted OAM modes. Over the past few years, progress has been made in understanding the advantages and limitations of using multiplexed OAM beams for communication systems. In this review paper, we highlight recent advances in the use of OAM multiplexing for high-capacity free-space optical and millimetre-wave communications. We discuss different technical challenges (e.g. atmospheric turbulence and crosstalk) as well as potential techniques to mitigate such degrading effects. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069770

Emergence of complex space-temporal order in nonlinear field theories

International Nuclear Information System (INIS)

Gleiser, Marcelo

2006-01-01

We investigate the emergence of time-dependent nonperturbative configurations during the evolution of nonlinear scalar field models with symmetric and asymmetric double-well potentials. Complex space-temporal behavior emerges as the system seeks to establish equipartition after a fast quench. We show that fast quenches may dramatically modify the decay rate of metastable states in first order phase transitions. We discuss possible applications in condensed matter systems and in inflationary cosmology. (author)

Soviet satellite communications science and technology

Energy Technology Data Exchange (ETDEWEB)

Birch, J.N.; Campanella, S.J.; Gordon, G.D.; McElroy, D.R.; Pritchard, W.L.; Stamminger, R.

1991-08-01

This is a report by six US scientists and engineers concerning the current state of the art and projections of future Soviet satellite communications technologies. The panel members are experts in satellite stabilization, spacecraft environments, space power generation, launch systems, spacecraft communications sciences and technologies, onboard processing, ground stations, and other technologies that impact communications. The panel assessed the Soviet ability to support high-data-rate space missions at 128 Mbps by evaluating current and projected Soviet satellite communications technologies. A variety of space missions were considered, including Earth-to-Earth communications via satellites in geostationary or highly elliptical orbits, those missions that require space-to-Earth communications via a direct path and those missions that require space-to-Earth communications via a relay satellite. Soviet satellite communications capability, in most cases, is 10 years behind that of the United States and other industrialized nations. However, based upon an analysis of communications links needed to support these missions using current Soviet capabilities, it is well within the current Soviet technology to support certain space missions outlined above at rates of 128 Mbps or higher, although published literature clearly shows that the Soviet Union has not exceeded 60 Mbps in its current space system. These analyses are necessary but not sufficient to determine mission data rates, and other technologies such as onboard processing and storage could limit the mission data rate well below that which could actually be supported via the communications links. Presently, the Soviet Union appears to be content with data rates in the low-Earth-orbit relay via geostationary mode of 12 Mbps. This limit is a direct result of power amplifier limits, spacecraft antenna size, and the utilization of K{sub u}-band frequencies. 91 refs., 16 figs., 15 tabs.

Communication in production animal medicine: modelling a complex interaction with the example of dairy herd health medicine

Directory of Open Access Journals (Sweden)

Kleen Joachim L

2011-07-01

Full Text Available Abstract Background The importance of communication skills in veterinary medicine is increasingly recognised. Appropriate communication skills towards the client are of utmost importance in both companion animal practice and production animal field and consultancy work. The need for building a relationship with the client, alongside developing a structure for the consultation is widely recognised and applies to both types of veterinary practice. Results Veterinary advisory practice in production animal medicine is, however, characterised by a more complex communication on different levels. While the person-orientated communication is a permanent process between veterinarian and client with a rather personal perspective and defines the roles of interaction, the problem-orientated communication deals with emerging difficulties; the objective is to solve an acute health problem. The solution - orientated communication is a form of communication in which both veterinarian and client address longstanding situations or problems with the objective to improve herd health and subsequently productivity performance. All three forms of communication overlap. Conclusions Based on this model, it appears useful for a veterinary practice to offer both a curative and an advisory service, but to keep these two separated when deemed appropriate. In veterinary education, the strategies and techniques necessary for solution orientated communication should be included in the teaching of communication skills.

Communication in production animal medicine: modelling a complex interaction with the example of dairy herd health medicine.

Science.gov (United States)

Kleen, Joachim L; Atkinson, Owen; Noordhuizen, Jos Ptm

2011-07-20

The importance of communication skills in veterinary medicine is increasingly recognised. Appropriate communication skills towards the client are of utmost importance in both companion animal practice and production animal field and consultancy work. The need for building a relationship with the client, alongside developing a structure for the consultation is widely recognised and applies to both types of veterinary practice. Veterinary advisory practice in production animal medicine is, however, characterised by a more complex communication on different levels. While the person-orientated communication is a permanent process between veterinarian and client with a rather personal perspective and defines the roles of interaction, the problem-orientated communication deals with emerging difficulties; the objective is to solve an acute health problem. The solution - orientated communication is a form of communication in which both veterinarian and client address longstanding situations or problems with the objective to improve herd health and subsequently productivity performance. All three forms of communication overlap. Based on this model, it appears useful for a veterinary practice to offer both a curative and an advisory service, but to keep these two separated when deemed appropriate. In veterinary education, the strategies and techniques necessary for solution orientated communication should be included in the teaching of communication skills.

Space-Based Reconfigurable Software Defined Radio Test Bed Aboard International Space Station

Science.gov (United States)

Reinhart, Richard C.; Lux, James P.

2014-01-01

The National Aeronautical and Space Administration (NASA) recently launched a new software defined radio research test bed to the International Space Station. The test bed, sponsored by the Space Communications and Navigation (SCaN) Office within NASA is referred to as the SCaN Testbed. The SCaN Testbed is a highly capable communications system, composed of three software defined radios, integrated into a flight system, and mounted to the truss of the International Space Station. Software defined radios offer the future promise of in-flight reconfigurability, autonomy, and eventually cognitive operation. The adoption of software defined radios offers space missions a new way to develop and operate space transceivers for communications and navigation. Reconfigurable or software defined radios with communications and navigation functions implemented in software or VHDL (Very High Speed Hardware Description Language) provide the capability to change the functionality of the radio during development or after launch. The ability to change the operating characteristics of a radio through software once deployed to space offers the flexibility to adapt to new science opportunities, recover from anomalies within the science payload or communication system, and potentially reduce development cost and risk by adapting generic space platforms to meet specific mission requirements. The software defined radios on the SCaN Testbed are each compliant to NASA's Space Telecommunications Radio System (STRS) Architecture. The STRS Architecture is an open, non-proprietary architecture that defines interfaces for the connections between radio components. It provides an operating environment to abstract the communication waveform application from the underlying platform specific hardware such as digital-to-analog converters, analog-to-digital converters, oscillators, RF attenuators, automatic gain control circuits, FPGAs, general-purpose processors, etc. and the interconnections among

Communication and control for networked complex systems

CERN Document Server

Peng, Chen; Han, Qing-Long

2015-01-01

This book reports on the latest advances in the study of Networked Control Systems (NCSs). It highlights novel research concepts on NCSs; the analysis and synthesis of NCSs with special attention to their networked character; self- and event-triggered communication schemes for conserving limited network resources; and communication and control co-design for improving the efficiency of NCSs. The book will be of interest to university researchers, control and network engineers, and graduate students in the control engineering, communication and network sciences interested in learning the core principles, methods, algorithms and applications of NCSs.

Analog Testing of Operations Concepts for Mitigation of Communication Latency During Human Space Exploration

Science.gov (United States)

Chappell, Steven P.; Abercromby, Andrew F.; Miller, Matthew J.; Halcon, Christopher; Gernhardt, Michael L.

2016-01-01

OBJECTIVES: NASA Extreme Environment Mission Operations (NEEMO) is an underwater spaceflight analog that allows a true mission-like operational environment and uses buoyancy effects and added weight to simulate different gravity levels. Three missions were undertaken from 2014-2015, NEEMO's 18-20. All missions were performed at the Aquarius undersea research habitat. During each mission, the effects of varying operations concepts and tasks type and complexity on representative communication latencies associated with Mars missions were studied. METHODS: 12 subjects (4 per mission) were weighed out to simulate near-zero or partial gravity extravehicular activity (EVA) and evaluated different operations concepts for integration and management of a simulated Earth-based science backroom team (SBT) to provide input and direction during exploration activities. Exploration traverses were planned in advance based on precursor data collected. Subjects completed science-related tasks including presampling surveys, geologic-based sampling, and marine-based sampling as a portion of their tasks on saturation dives up to 4 hours in duration that were to simulate extravehicular activity (EVA) on Mars or the moons of Mars. One-way communication latencies, 5 and 10 minutes between space and mission control, were simulated throughout the missions. Objective data included task completion times, total EVA times, crew idle time, translation time, SBT assimilation time (defined as time available for SBT to discuss data/imagery after it has been collected, in addition to the time taken to watch imagery streaming over latency). Subjective data included acceptability, simulation quality, capability assessment ratings, and comments. RESULTS: Precursor data can be used effectively to plan and execute exploration traverse EVAs (plans included detailed location of science sites, high-fidelity imagery of the sites, and directions to landmarks of interest within a site). Operations concepts that

On the average complexity of sphere decoding in lattice space-time coded multiple-input multiple-output channel

KAUST Repository

Abediseid, Walid

2012-12-21

The exact average complexity analysis of the basic sphere decoder for general space-time codes applied to multiple-input multiple-output (MIMO) wireless channel is known to be difficult. In this work, we shed the light on the computational complexity of sphere decoding for the quasi- static, lattice space-time (LAST) coded MIMO channel. Specifically, we drive an upper bound of the tail distribution of the decoder\\'s computational complexity. We show that when the computational complexity exceeds a certain limit, this upper bound becomes dominated by the outage probability achieved by LAST coding and sphere decoding schemes. We then calculate the minimum average computational complexity that is required by the decoder to achieve near optimal performance in terms of the system parameters. Our results indicate that there exists a cut-off rate (multiplexing gain) for which the average complexity remains bounded. Copyright © 2012 John Wiley & Sons, Ltd.

Space-Time Equalization for High-Speed Wireless Digital Communications Based on Multipath-Incorporating Matched Filtering, Zero Forcing Equalization, and MMSE

National Research Council Canada - National Science Library

Zoltowski, Michael D

2003-01-01

The project has successfully demonstrated reduced-rank, space-time equalization for high-speed wireless digital communications capable of reliably transmitting multimedia data in support of military...

Reconceptualising ‘Time’ and ‘Space’ in the Era of Electronic Media and Communications

Directory of Open Access Journals (Sweden)

Panayiota Tsatsou

2009-07-01

Full Text Available This paper examines to what extent electronic media and communications have contributed to currently changing concepts of time and space and how crucial their role is in experiencing temporality, spatiality and mobility. The paper argues that media and communication technologies play a complex part in shifting conceptions of time and space, without diminishing to insignificance the concepts of time and space or subjective experiences of them. On the contrary, by challenging established conceptual approaches to time and space, electronic media could be considered to 'mediate' time and space, problematising the multi-layered significance of how they are experienced today. The paper is divided into three sections. First, it presents theoretical approaches to time and space, and it discusses the two seemingly contrasting approaches of 'time-space distanciation' and 'time-space compression'. Second, it develops a historical analysis of the ways in which media have empirically modified the concepts of time and space, and it discusses the examples of 'internet time' and new 'electronic spaces' to challenge the argument of temporal simultaneity and non-significance of space in the new digital era, respectively. Viewing the historical changes of space in particular as intimately linked to the shifting conceptualisation of place, the third section examines the emergence of a perception of place as 'non-place', whilst it argues in favour of the counterthesis of a mediated sense of place. In this regard, the paper espouses the thesis that electronic communications have succeeded in interconnecting remote places without eliminating their importance.

Sources of variability in human communicative skills

Directory of Open Access Journals (Sweden)

Inge eVolman

2012-11-01

Full Text Available When established communication systems cannot be used, people rapidly create novel systems to modify the mental state of another agent according to their intentions. However, there are dramatic inter-individual differences in the implementation of this human competence for communicative innovation. Here we characterize psychological sources of inter-individual variability in the ability to build a shared communication system from scratch. We consider two potential sources of variability in communicative skills. Cognitive traits of two individuals could independently influence their joint ability to establish a communication system. Another possibility is that the overlap between those individual traits influences the communicative performance of a dyad. We assess these possibilities by quantifying the relationship between cognitive traits and behavior of communicating dyads. Cognitive traits were assessed with psychometric scores quantifying cooperative attitudes and fluid intelligence. Competence for implementing successful communicative innovations was assessed by using a non-verbal communicative task. Individual capacities influence communicative success when communicative innovations are generated. Dyadic similarities and individual traits modulate the type of communicative strategy chosen. The ability to establish novel communicative actions was influenced by a combination of the communicator’s ability to understand intentions and the addressee’s ability to recognize patterns. Communicative pairs with comparable systemizing abilities or behavioral inhibition were more likely to explore the search space of possible communicative strategies by systematically adding new communicative behaviors to those already available. No individual psychometric measure seemed predominantly responsible for communicative success. These findings support the notion that the human ability for fast communicative innovations represents a special type of

Dember effect photodetectors and the effects of turbulence on free-space optical communication systems

Science.gov (United States)

Dikmelik, Yamac

High-speed free-space optical communication systems have recently utilized components that have been developed for fiber-optic communication systems. The received laser beam in such a system must be coupled into a single-mode fiber at the input of a commercially available receiver module or a wavelength division demultiplexer. However, one effect of propagation through atmospheric turbulence is that the spatial coherence of a laser beam is degraded and the percentage of the available power that can be coupled into the single-mode fiber is limited. This dissertation presents a numerical evaluation of fiber coupling efficiency for laser light distorted by atmospheric turbulence. The results for weak fluctuation conditions provide the level of coupling efficiency that can be expected for a given turbulence strength. In addition, the results show that the link distance must be limited to 400 m under moderate turbulence conditions if the link budget requires a coupling efficiency of 0.1. We also investigate the use of a coherent fiber array as a receiver structure to improve the fiber coupling efficiency of a free-space optical communication system. Our numerical results show that a coherent fiber array that consists of seven subapertures would increase fiber coupling efficiency by a significant amount for representative turbulence conditions and link distances. The use of photo-emf detectors as elements of a wavefront sensor for an adaptive optics system is also considered as an alternative method of reducing the effects of turbulence on a free-space optical communication system. Dember and photo-emf currents are investigated in silicon photoconductive detectors both theoretically and experimentally. Our results show that Dember photocurrents dominate the response of high-purity silicon samples with top surface electrodes to a moving interference pattern. The use of surface electrodes leads to shadowed regions beneath the electrodes and Dember photocurrents appear

All ASD complex and real 4-dimensional Einstein spaces with Λ≠0 admitting a nonnull Killing vector

Science.gov (United States)

Chudecki, Adam

2016-12-01

Anti-self-dual (ASD) 4-dimensional complex Einstein spaces with nonzero cosmological constant Λ equipped with a nonnull Killing vector are considered. It is shown that any conformally nonflat metric of such spaces can be always brought to a special form and the Einstein field equations can be reduced to the Boyer-Finley-Plebański equation (Toda field equation). Some alternative forms of the metric are discussed. All possible real slices (neutral, Euclidean and Lorentzian) of ASD complex Einstein spaces with Λ≠0 admitting a nonnull Killing vector are found.

Computer-Mediated Communication Systems

Directory of Open Access Journals (Sweden)

Bin Yu

2011-10-01

Full Text Available The essence of communication is to exchange and share information. Computers provide a new medium to human communication. CMC system, composed of human and computers, absorbs and then extends the advantages of all former formats of communication, embracing the instant interaction of oral communication, the abstract logics of printing dissemination, and the vivid images of movie and television. It also creates a series of new communication formats, such as Hyper Text, Multimedia etc. which are the information organizing methods, and cross-space message delivering patterns. Benefiting from the continuous development of technique and mechanism, the computer-mediated communication makes the dream of transmitting information cross space and time become true, which will definitely have a great impact on our social lives.

On communicating the complexity (...) Part 1

DEFF Research Database (Denmark)

Langeland, Lise

1998-01-01

campaigns. The general implications fro environmental and social communication are presented and discussed. The article concludes the business can address the underlying environmental and social issues in an informative and responsible manner and that the case study suggests the possibility of doing so...... dimensions. Though a wider range of fair trade products exist, the case study only draws on the compaigns related to coffee. After an introduction to the social problems underlying fair trade, the article studies the communication undertaken by the Max Havelaar Foundation, drawing on material from various...

Space Communication Artificial Intelligence for Link Evaluation Terminal (SCAILET)

Science.gov (United States)

Shahidi, Anoosh K.; Schlegelmilch, Richard F.; Petrik, Edward J.; Walters, Jerry L.

1992-01-01

A software application to assist end-users of the high burst rate (HBR) link evaluation terminal (LET) for satellite communications is being developed. The HBR LET system developed at NASA Lewis Research Center is an element of the Advanced Communications Technology Satellite (ACTS) Project. The HBR LET is divided into seven major subsystems, each with its own expert. Programming scripts, test procedures defined by design engineers, set up the HBR LET system. These programming scripts are cryptic, hard to maintain and require a steep learning curve. These scripts were developed by the system engineers who will not be available for the end-users of the system. To increase end-user productivity a friendly interface needs to be added to the system. One possible solution is to provide the user with adequate documentation to perform the needed tasks. With the complexity of this system the vast amount of documentation needed would be overwhelming and the information would be hard to retrieve. With limited resources, maintenance is another reason for not using this form of documentation. An advanced form of interaction is being explored using current computer techniques. This application, which incorporates a combination of multimedia and artificial intelligence (AI) techniques to provided end-users with an intelligent interface to the HBR LET system, is comprised of an intelligent assistant, intelligent tutoring, and hypermedia documentation. The intelligent assistant and tutoring systems address the critical programming needs of the end-user.

Complex network analysis of state spaces for random Boolean networks

Energy Technology Data Exchange (ETDEWEB)

Shreim, Amer [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Berdahl, Andrew [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Sood, Vishal [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Grassberger, Peter [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Paczuski, Maya [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada)

2008-01-15

We apply complex network analysis to the state spaces of random Boolean networks (RBNs). An RBN contains N Boolean elements each with K inputs. A directed state space network (SSN) is constructed by linking each dynamical state, represented as a node, to its temporal successor. We study the heterogeneity of these SSNs at both local and global scales, as well as sample to-sample fluctuations within an ensemble of SSNs. We use in-degrees of nodes as a local topological measure, and the path diversity (Shreim A et al 2007 Phys. Rev. Lett. 98 198701) of an SSN as a global topological measure. RBNs with 2 {<=} K {<=} 5 exhibit non-trivial fluctuations at both local and global scales, while K = 2 exhibits the largest sample-to-sample (possibly non-self-averaging) fluctuations. We interpret the observed 'multi scale' fluctuations in the SSNs as indicative of the criticality and complexity of K = 2 RBNs. 'Garden of Eden' (GoE) states are nodes on an SSN that have in-degree zero. While in-degrees of non-GoE nodes for K > 1 SSNs can assume any integer value between 0 and 2{sup N}, for K = 1 all the non-GoE nodes in a given SSN have the same in-degree which is always a power of two.

Complex network analysis of state spaces for random Boolean networks

International Nuclear Information System (INIS)

Shreim, Amer; Berdahl, Andrew; Sood, Vishal; Grassberger, Peter; Paczuski, Maya

2008-01-01

We apply complex network analysis to the state spaces of random Boolean networks (RBNs). An RBN contains N Boolean elements each with K inputs. A directed state space network (SSN) is constructed by linking each dynamical state, represented as a node, to its temporal successor. We study the heterogeneity of these SSNs at both local and global scales, as well as sample to-sample fluctuations within an ensemble of SSNs. We use in-degrees of nodes as a local topological measure, and the path diversity (Shreim A et al 2007 Phys. Rev. Lett. 98 198701) of an SSN as a global topological measure. RBNs with 2 ≤ K ≤ 5 exhibit non-trivial fluctuations at both local and global scales, while K = 2 exhibits the largest sample-to-sample (possibly non-self-averaging) fluctuations. We interpret the observed 'multi scale' fluctuations in the SSNs as indicative of the criticality and complexity of K = 2 RBNs. 'Garden of Eden' (GoE) states are nodes on an SSN that have in-degree zero. While in-degrees of non-GoE nodes for K > 1 SSNs can assume any integer value between 0 and 2 N , for K = 1 all the non-GoE nodes in a given SSN have the same in-degree which is always a power of two

Selection of a Data Acquisition and Controls System Communications and Software Architecture for Johnson Space Center's Space Environment Simulation Laboratory Thermal and Vacuum Test Facilities

Science.gov (United States)

Jordan, Eric A.

2004-01-01

Upgrade of data acquisition and controls systems software at Johnson Space Center's Space Environment Simulation Laboratory (SESL) involved the definition, evaluation and selection of a system communication architecture and software components. A brief discussion of the background of the SESL and its data acquisition and controls systems provides a context for discussion of the requirements for each selection. Further framework is provided as upgrades to these systems accomplished in the 1990s and in 2003 are compared to demonstrate the role that technological advances have had in their improvement. Both of the selections were similar in their three phases; 1) definition of requirements, 2) identification of candidate products and their evaluation and testing and 3) selection by comparison of requirement fulfillment. The candidates for the communication architecture selection embraced several different methodologies which are explained and contrasted. Requirements for this selection are presented and the selection process is described. Several candidates for the software component of the data acquisition and controls system are identified, requirements for evaluation and selection are presented, and the evaluation process is described.

"You Get More Than You Give": Experiences of Community Partners in Facilitating Active Recreation with Individuals who have Complex Communication Needs.

Science.gov (United States)

Hajjar, David J; McCarthy, John W; Benigno, Joann P; Chabot, Jennifer

2016-06-01

Recreation is an essential part of life that provides enriching experiences that may define one's life course similar to careers or other interests. An understanding of the role of volunteers in active community-based recreational programs can help to generate ways to enhance participation and contribute to additional communication opportunities with people who have complex communication needs. Nine volunteers from two adaptive ski programs and one therapeutic horseback-riding program in the Northeast region of the United States participated in semi-structured interviews. Audio-recordings were transcribed and analyzed and resulted in five thematic areas: (a) benefits, (b) why individuals volunteer, (c) barriers, (d) successful program supports, and (e) who are the riders and skiers using AAC. The findings provided insight to support the notion that active community-based recreational activities foster an environment for communication, meaningful engagement, and social relationships between volunteers and people with complex communication needs.

Reconfigurable, Intelligently-Adaptive, Communication System, an SDR Platform

Science.gov (United States)

Roche, Rigoberto J.; Shalkhauser, Mary Jo; Hickey, Joseph P.; Briones, Janette C.

2016-01-01

The Space Telecommunications Radio System (STRS) provides a common, consistent framework to abstract the application software from the radio platform hardware. STRS aims to reduce the cost and risk of using complex, configurable and reprogrammable radio systems across NASA missions. The NASA Glenn Research Center (GRC) team made a software defined radio (SDR) platform STRS compliant by adding an STRS operating environment and a field programmable gate array (FPGA) wrapper, capable of implementing each of the platforms interfaces, as well as a test waveform to exercise those interfaces. This effort serves to provide a framework toward waveform development onto an STRS compliant platform to support future space communication systems for advanced exploration missions. The use of validated STRS compliant applications provides tested code with extensive documentation to potentially reduce risk, cost and e ort in development of space-deployable SDRs. This paper discusses the advantages of STRS, the integration of STRS onto a Reconfigurable, Intelligently-Adaptive, Communication System (RIACS) SDR platform, and the test waveform and wrapper development e orts. The paper emphasizes the infusion of the STRS Architecture onto the RIACS platform for potential use in next generation flight system SDRs for advanced exploration missions.

Language complexity modulates 8- and 10-year-olds' success at using their theory of mind abilities in a communication task.

Science.gov (United States)

Wang, J Jessica; Ali, Muna; Frisson, Steven; Apperly, Ian A

2016-09-01

Basic competence in theory of mind is acquired during early childhood. Nonetheless, evidence suggests that the ability to take others' perspectives in communication improves continuously from middle childhood to the late teenage years. This indicates that theory of mind performance undergoes protracted developmental changes after the acquisition of basic competence. Currently, little is known about the factors that constrain children's performance or that contribute to age-related improvement. A sample of 39 8-year-olds and 56 10-year-olds were tested on a communication task in which a speaker's limited perspective needed to be taken into account and the complexity of the speaker's utterance varied. Our findings showed that 10-year-olds were generally less egocentric than 8-year-olds. Children of both ages committed more egocentric errors when a speaker uttered complex sentences compared with simple sentences. Both 8- and 10-year-olds were affected by the demand to integrate complex sentences with the speaker's limited perspective and to a similar degree. These results suggest that long after children's development of simple visual perspective-taking, their use of this ability to assist communication is substantially constrained by the complexity of the language involved. Copyright © 2015 Elsevier Inc. All rights reserved.

Complex Conjugated certificateless-based signcryption with differential integrated factor for secured message communication in mobile network.

Directory of Open Access Journals (Sweden)

Sumithra Alagarsamy

Full Text Available Certificateless-based signcryption overcomes inherent shortcomings in traditional Public Key Infrastructure (PKI and Key Escrow problem. It imparts efficient methods to design PKIs with public verifiability and cipher text authenticity with minimum dependency. As a classic primitive in public key cryptography, signcryption performs validity of cipher text without decryption by combining authentication, confidentiality, public verifiability and cipher text authenticity much more efficiently than the traditional approach. In this paper, we first define a security model for certificateless-based signcryption called, Complex Conjugate Differential Integrated Factor (CC-DIF scheme by introducing complex conjugates through introduction of the security parameter and improving secured message distribution rate. However, both partial private key and secret value changes with respect to time. To overcome this weakness, a new certificateless-based signcryption scheme is proposed by setting the private key through Differential (Diff Equation using an Integration Factor (DiffEIF, minimizing computational cost and communication overhead. The scheme is therefore said to be proven secure (i.e. improving the secured message distributing rate against certificateless access control and signcryption-based scheme. In addition, compared with the three other existing schemes, the CC-DIF scheme has the least computational cost and communication overhead for secured message communication in mobile network.

Complex Conjugated certificateless-based signcryption with differential integrated factor for secured message communication in mobile network.

Science.gov (United States)

Alagarsamy, Sumithra; Rajagopalan, S P

2017-01-01

Certificateless-based signcryption overcomes inherent shortcomings in traditional Public Key Infrastructure (PKI) and Key Escrow problem. It imparts efficient methods to design PKIs with public verifiability and cipher text authenticity with minimum dependency. As a classic primitive in public key cryptography, signcryption performs validity of cipher text without decryption by combining authentication, confidentiality, public verifiability and cipher text authenticity much more efficiently than the traditional approach. In this paper, we first define a security model for certificateless-based signcryption called, Complex Conjugate Differential Integrated Factor (CC-DIF) scheme by introducing complex conjugates through introduction of the security parameter and improving secured message distribution rate. However, both partial private key and secret value changes with respect to time. To overcome this weakness, a new certificateless-based signcryption scheme is proposed by setting the private key through Differential (Diff) Equation using an Integration Factor (DiffEIF), minimizing computational cost and communication overhead. The scheme is therefore said to be proven secure (i.e. improving the secured message distributing rate) against certificateless access control and signcryption-based scheme. In addition, compared with the three other existing schemes, the CC-DIF scheme has the least computational cost and communication overhead for secured message communication in mobile network.

An assessment of the status and trends in satellite communications 1986-2000: An information document prepared for the Communications Subcommittee of the Space Applications Advisory Committee

Science.gov (United States)

Poley, W. A.; Stevens, G. H.; Stevenson, S. M.; Lekan, J.; Arth, C. H.; Hollansworth, J. E.; Miller, E. F.

1986-01-01

This is a response to a Space Applications Advisory Committee (SAAC) request for information about the status and trends in satellite communications, to be used to support efforts to conceive and recommend long range goals for NASA communications activities. Included in this document are assessments of: (1) the outlook for satellite communications, including current applications, potential future applications, and impact of the changing environment such as optical fiber networks, the Integrated Services Digital Network (ISDN) standard, and the rapidly growing market for Very Small Aperture Terminals (VSAT); (2) the restrictions imposed by our limited spectrum resource; and (3) technology needs indicated by future trends. Potential future systems discussed include: large powerful satellites for providing personal communications; VSAT compatible satellites with onboard switching and having voice capability; large satellites which offer a pervasive T1 network service (primarily for video-phone); and large geostationary communications facilities which support common use by several carriers. Also, discussion is included of NASA particular needs and possible future systems. Based on the mentioned system concepts, specific technology recommendations are provided for the time frames of now - 1993, 1994 - 2000, and 2000 - 2010.

Design of Hybrid Mobile Communication Networks for Planetary Exploration

Science.gov (United States)

Alena, Richard L.; Ossenfort, John; Lee, Charles; Walker, Edward; Stone, Thom

2004-01-01

The Mobile Exploration System Project (MEX) at NASA Ames Research Center has been conducting studies into hybrid communication networks for future planetary missions. These networks consist of space-based communication assets connected to ground-based Internets and planetary surface-based mobile wireless networks. These hybrid mobile networks have been deployed in rugged field locations in the American desert and the Canadian arctic for support of science and simulation activities on at least six occasions. This work has been conducted over the past five years resulting in evolving architectural complexity, improved component characteristics and better analysis and test methods. A rich set of data and techniques have resulted from the development and field testing of the communication network during field expeditions such as the Haughton Mars Project and NASA Mobile Agents Project.

Quantum Limits of Space-to-Ground Optical Communications

Science.gov (United States)

Hemmati, H.; Dolinar, S.

2012-01-01

For a pure loss channel, the ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light): (1) Capacity-achieving receiver (measurement) is yet to be determined. (2) Heterodyne detection approaches the ultimate capacity at high mean photon numbers. (3) Photon-counting approaches the ultimate capacity at low mean photon numbers. A number of current technology limits drive the achievable performance of free-space communication links. Approaching fundamental limits in the bandwidth-limited regime: (1) Heterodyne detection with high-order coherent-state modulation approaches ultimate limits. SOA improvements to laser phase noise, adaptive optics systems for atmospheric transmission would help. (2) High-order intensity modulation and photon-counting can approach heterodyne detection within approximately a factor of 2. This may have advantages over coherent detection in the presence of turbulence. Approaching fundamental limits in the photon-limited regime (1) Low-duty cycle binary coherent-state modulation (OOK, PPM) approaches ultimate limits. SOA improvements to laser extinction ratio, receiver dark noise, jitter, and blocking would help. (2) In some link geometries (near field links) number-state transmission could improve over coherent-state transmission

Hybrid microtransmitter for free-space optical spacecraft communication: design, manufacturing, and characterization

Science.gov (United States)

Lotfi, Sara; Palmer, Kristoffer; Kratz, Henrik; Thornell, Greger

2009-02-01

Optical intra-communication links are investigated by several currently operational qualification missions. Compared with RF communication systems, the optical domain obtains a wider bandwidth, enables miniaturized spacecraft and reduced power consumption. In this project, a microtransmitter is designed and manufactured for formation flying spacecraft with transmission rates of 1 Gbit/s. Simulations in Matlab and Simulink show that a BER of 10-9 can be achieved with aperture sizes of 1 cm and a transmitter output peak power of 12 mW for a distance of 10 km. The results show that the performance of the communication link decreases due to mechanical vibrations in the spacecraft together with a narrow laser beam. A dual-axis microactuator designed as a deflectable mirror has been developed for the laser beam steering where the fabrication is based on a double-sided, bulk micromachining process. The mirror actuates by joints consisting of v-grooves filled with SU-8 polymer. The deflection is controlled by integrated resistive heaters in the joints causing the polymer to expand thermally. Results show that the mirror actuates 20-30° in the temperature interval 25-250°C. Flat Fresnel lenses made of Pyrex 7740 are used to collimate the laser beam. These lenses are simulated in the Comsol software and optimized for a 670 nm red VCSEL. The lenses are manufactured using lithography and reactive ion etching. All tests are made in a normal laboratory environment, but the effect of the space environment is discussed.

Analysis of fog effects on terrestrial Free Space optical communication links

KAUST Repository

Esmail, Maged Abdullah

2016-07-26

In this paper, we consider and examine fog measurement data, coming from several locations in Europe and USA, and attempt to derive a unified model for fog attenuation in free space optics (FSO) communication links. We evaluate and compare the performance of our proposed model to that of many well-known alternative models. We found that our proposed model, achieves an average RMSE that outperforms them by more than 9 dB. Furthermore, we have studied the performance of the FSO system using different performance metrics such as signal-to-noise (SNR) ratio, bit error rate (BER), and channel capacity. Our results show that FSO is a short range technology. Therefore, FSO is expected to find its place in future networks that will have small cell size, i.e., <1 km diameter. Moreover, our investigation shows that under dense fog, it is difficult to maintain a communications link because of the high signal attenuation, which requires switching the communications to RF backup. Our results show that increasing the transmitted power will improve the system performance under light fog. However, under heavy fog, the effect is minor. To enhance the system performance under low visibility range, multi-hop link is used which can enhance the power budget by using short segments links. Using 22 dBm transmitted power, we obtained BER=10-3 over 1 km link length with 600 m visibility range which corresponds to light fog. However, under lower visibility range equals 40 m that corresponds to dense fog, we obtained the same BER but over 200 m link length. © 2016 IEEE.

Exploring the dynamics of formal and informal networks in complex multi-team development projects

DEFF Research Database (Denmark)

Kratzer, J.; Gemuenden, H. G.; Lettl, Christopher

2007-01-01

The increasing number of complex multi-team projects and the scarcity of knowledge about how to run them successfully, create a need for systematic empirical studies. We attempt to lessen this empirical gap by examining the overlap and structure of formally ascribed design interfaces and informal...... communication networks between participating teams in two complex multi-team projects in the space industry. We study the two projects longitudinally throughout the design and integration phases of product development. There are three major findings. First, formally ascribed design interfaces and informal...... communication networks overlap only marginally. Second, the structure of informal communication remains largely stable in the transition from the design to the integration phase. The third and most intriguing finding is that the weak overlap between formally ascribed design interfaces and the informal...

Web-based communications systems: innovate solutions to complex development challenges

International Nuclear Information System (INIS)

Levy, D.S.; Sordi, G.M.; Villavicencio, A.L.H.; Biazini Filho, F.

2015-01-01

This research work focus on the potential value of Information and Communication Technologies (ICTs) to enhance communication and education on Radiological Protection throughout Brazil. ICTs present unprecedented opportunities to innovate solutions to complex development issues, in this large country where it is a strong challenge to ensure access to information to as many people as possible, minimizing costs and optimizing results. Therefore, taking advantage of the impact of ICTs in modern Information Society and its institutions, some research works include education for workers, researchers and the public, offering conditions for learning and improving professional and personal skills. UNIPRORAD is a research work of informatization of radiological protection programs to offer unified programs and inter-related information in Portuguese. The system provides Brazilian facilities and researchers a complete repository for research, consultation and information. The content includes the best practices for optimization and monitoring programs, taking into account that in order to establish a Radiation Protection Plan or a Radiation Emergency Plan, there must be observed all procedures based on national and international recommendations published by different organizations over the past decades: International Commission on Radiological Protection (ICRP), International Atomic Energy Agency (IAEA) and National Nuclear Energy Commission (CNEN). Other than the efforts to disseminate information to radioactive facilities and researches, it is equally essential to invest in education and communication to increase public knowledge and understanding of the benefits of Nuclear Technology, such as food irradiation and social responsibility for electric power generation, for public acceptance of Nuclear Technology depends on public understanding of radiation and its effects on individuals, workers and environment. This research work aims to present several important initiatives

Communicating in complex situations: a normative approach to HIV-related talk among parents who are HIV+.

Science.gov (United States)

Edwards, Laura L; Donovan-Kicken, Erin; Reis, Janet S

2014-01-01

Parents with HIV/AIDS are confronted with unique challenges when discussing HIV-related information with their children. Strategies for navigating these challenges effectively have not been systematically examined. In this study, we conducted in-depth interviews with 76 parents with HIV/AIDS who had children ages 10-18 years. Guided by O'Keefe and Delia's definition of a complex communication situation and Goldsmith's normative approach to interpersonal communication, we examined parents' goals for discussing HIV-related information, factors that made conversations challenging, and instances where these conversational purposes conflicted with one another. Our data reveal the following parent-adolescent communication predicaments: relaying safety information about HIV while minimizing child anxiety, modeling open family communication without damaging one's parental identity, and balancing parent-child relational needs amid living with an unpredictable health condition. Parents also described a variety of strategies for mitigating challenges when discussing HIV-related topics. Strategies parents perceived as effective included reframing HIV as a chronic, manageable illness; keeping talk educational; and embedding HIV-related topics within more general conversations. The theoretical and practical applications of these findings are discussed with regard to their relevance to health communication scholars and HIV care professionals.

Communicating through Probabilities: Does Quantum Theory Optimize the Transfer of Information?

Directory of Open Access Journals (Sweden)

William K. Wootters

2013-08-01

Full Text Available A quantum measurement can be regarded as a communication channel, in which the parameters of the state are expressed only in the probabilities of the outcomes of the measurement. We begin this paper by considering, in a non-quantum-mechanical setting, the problem of communicating through probabilities. For example, a sender, Alice, wants to convey to a receiver, Bob, the value of a continuous variable, θ, but her only means of conveying this value is by sending Bob a coin in which the value of θ is encoded in the probability of heads. We ask what the optimal encoding is when Bob will be allowed to flip the coin only a finite number of times. As the number of tosses goes to infinity, we find that the optimal encoding is the same as what nature would do if we lived in a world governed by real-vector-space quantum theory. We then ask whether the problem might be modified, so that the optimal communication strategy would be consistent with standard, complex-vector-space quantum theory.

Non-Hermitian multi-particle systems from complex root spaces

International Nuclear Information System (INIS)

Fring, Andreas; Smith, Monique

2012-01-01

We provide a general construction procedure for antilinearly invariant complex root spaces. The proposed method is generic and may be applied to any Weyl group allowing us to take any element of the group as a starting point for the construction. Worked-out examples for several specific Weyl groups are presented, focusing especially on those cases for which no solutions were found previously. When applied to the defining relations of models based on root systems, this usually leads to non-Hermitian models, which are nonetheless physically viable in a self-consistent sense as they are antilinearly invariant by construction. We discuss new types of Calogero models based on these complex roots. In addition, we propose an alternative construction leading to q-deformed roots. We employ the latter type of roots to formulate a new version of affine Toda field theories based on non-simply laced root systems. These models exhibit on the classical level a strong–weak duality in the coupling constant equivalent to a Lie algebraic duality, which is known for the quantum version of the undeformed case. (paper)

Development of Operational Free-Space-Optical (FSO) Laser Communication Systems Final Report CRADA No. TC02093.0

Energy Technology Data Exchange (ETDEWEB)

Ruggiero, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Orgren, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-08-15

This project was a collaborative effort between Lawrence Livermore National Security, LLC (formerly The Regents of the University of California)/Lawrence Livermore National Laboratory (LLNL) and LGS Innovations, LLC (formerly Lucent Technologies, Inc.), to develop long-range and mobile operational free-space optical (FSO) laser communication systems for specialized government applications. LLNL and LGS Innovations formerly Lucent Bell Laboratories Government Communications Systems performed this work for a United States Government (USG) Intelligence Work for Others (I-WFO) customer, also referred to as "Government Customer", or "Customer" and "Government Sponsor." The CRADA was a critical and required part of the LLNL technology transfer plan for the customer.

Social Media and the Transformation of Public Space

OpenAIRE

José van Dijck; Thomas Poell

2015-01-01

This introduction to the Special Issue of Social Media + Society discusses the key theoretical perspectives and methodological approaches needed to gain insight into how social platforms intervene in public space. It starts by highlighting how in the emerging platform society public and private communication is reshaped by social media’s commercial mechanisms, transforming the political economy of the media landscape. Given the complex character of this society, it is essential to employ diff...

Development of evaluation method for the quality of NPP MCR operators' communication using work domain analysis (WDA)

International Nuclear Information System (INIS)

Jang, In Seok

2010-02-01

Evolution of work demands has changed industrial evolution to computerization which makes systems complex and complicated: this field is called Complex Socio-Technical Systems. As communication failure is one problem of Complex Socio-Technical Systems, it has been discovered that communication failure is the reason for many incidents and accidents in various industries, including the nuclear, aerospace and railway industries. Despite the fact that there have been many studies on the severity of communication failure, there is no evaluation method for operators' communication quality in NPPs. Therefore, the objectives of this study are to develop an evaluation method for the quality of NPP Main Control Room (MCR) operators' communication and to apply the proposed method to operators in a full-scope simulator. In order to develop the proposed method, the Work Domain Analysis (WDA) method is introduced. Several characteristic of WDA, such as Abstraction Decomposition Space (ADS) and the diagonal of ADS are the key points in developing an evaluation method for the quality of NPP MCR operators' communication. In addition, in order to apply the proposed method, nine teams working in NPPs participated in the field simulation. Evaluation results reveal that operators' communication quality was higher as larger portion of components in the developed evaluation criteria were mentioned. Therefore, the proposed method could be a useful one for evaluating the communication quality in any complex system. In order to verify that the proposed method is meaningful to evaluate communication quality, the evaluation results were further investigated with objective performance measures. Further investigation of the evaluation results also supports the idea that the proposed method can be used in evaluating communication quality

A new differential calculus on a complex banach space with application to variational problems of quantum theory

International Nuclear Information System (INIS)

Sharma, C.S.; Rebelo, I.

1975-01-01

It is proved that a semilinear function on a complex banach space is not differentiable according to the usual definition of differentiability in the calculus on banch spaces. It is shown that this result makes the calculus largely inapplicable to the solution od variational problems of quantum mechanics. A new concept of differentiability called semidifferentiability is defined. This generalizes the standard concept of differentiability in a banach space and the resulting calculus is particularly suitable for optimizing real-value functions on a complex banach space and is directly applicable to the solution of quantum mechanical variational problems. As an example of such application a rigorous proof of a generalized version of a result due to Sharma (J. Phys. A; 2:413 (1969)) is given. In the course of this work a new concept of prelinearity is defined and some standard results in the calculus in banach spaces are extended and generalized into more powerful ones applicable directly to prelinear functions and hence yielding the standard results for linear function as particular cases. (author)

The performance of orthogonal frequency division multiplexing in the weak turbulence regime of free space optics communication systems

International Nuclear Information System (INIS)

Selvi, M; Murugesan, K

2012-01-01

Radio on free space optics—RoFSO—has gained momentum in research because of its cost effectiveness and efficiency in transferring data at a high rate that is comparable to that for optical fiber media. While the transmission data rate is limited in fiber due to dispersion and nonlinearity, such effects do not prevail in FSO communication links. The data rate depends mainly on the switching speed of the optoelectronic devices. With the characteristics of free space being random in nature, the performance of RoFSO is primarily governed by atmospheric conditions. In this paper, we evaluate the performance of the orthogonal frequency division multiplexing (OFDM) signal in free space and compare against its counterpart radio frequency (RF) wireless communication systems. Simulations have been done on the atmospheric conditions by means of modeling the scintillation effect using log-normal distribution. The performance of the proposed system under two different base-band modulations, namely OFDM–PSK (phase shift keying) and QAM (quadrature amplitude modulation) in weak turbulence conditions is studied. It is found that PSK performs better than QAM. Also the M-ary performance analysis shows that 3–5 dB improvement in the signal to noise ratio is obtained for OFDM based FSO transmission compared to RF based wireless transmission. (paper)

Transceiver for Space Station Freedom

Science.gov (United States)

Fitzmaurice, M.; Bruno, R.

1990-07-01

This paper describes the design of the Laser Communication Transceiver (LCT) system which was planned to be flight tested as an attached payload on Space Station Freedom. The objective in building and flight-testing the LCT is to perform a broad class of tests addressing the critical aspects of space-based optical communications systems, providing a base of experience for applying laser communications technology toward future communications needs. The LCT's functional and performance requirements and capabilities with respect to acquisition, spatial tracking and pointing, communications, and attitude determination are discussed.

Prediction of rain effects on earth-space communication links operating in the 10 to 35 GHz frequency range

Science.gov (United States)

Stutzman, Warren L.

1989-01-01

This paper reviews the effects of precipitation on earth-space communication links operating the 10 to 35 GHz frequency range. Emphasis is on the quantitative prediction of rain attenuation and depolarization. Discussions center on the models developed at Virginia Tech. Comments on other models are included as well as literature references to key works. Also included is the system level modeling for dual polarized communication systems with techniques for calculating antenna and propagation medium effects. Simple models for the calculation of average annual attenuation and cross-polarization discrimination (XPD) are presented. Calculation of worst month statistics are also presented.

Securing Data for Space Communications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NASA's vision of data exchange between space and ground nodes would involve the space network accessing public infrastructure such as the internet. Hence, advanced...

Global synchronization of complex dynamical networks through digital communication with limited data rate.

Science.gov (United States)

Wang, Yan-Wu; Bian, Tao; Xiao, Jiang-Wen; Wen, Changyun

2015-10-01

This paper studies the global synchronization of complex dynamical network (CDN) under digital communication with limited bandwidth. To realize the digital communication, the so-called uniform-quantizer-sets are introduced to quantize the states of nodes, which are then encoded and decoded by newly designed encoders and decoders. To meet the requirement of the bandwidth constraint, a scaling function is utilized to guarantee the quantizers having bounded inputs and thus achieving bounded real-time quantization levels. Moreover, a new type of vector norm is introduced to simplify the expression of the bandwidth limit. Through mathematical induction, a sufficient condition is derived to ensure global synchronization of the CDNs. The lower bound on the sum of the real-time quantization levels is analyzed for different cases. Optimization method is employed to relax the requirements on the network topology and to determine the minimum of such lower bound for each case, respectively. Simulation examples are also presented to illustrate the established results.

Space-Time Chip Equalization for Maximum Diversity Space-Time Block Coded DS-CDMA Downlink Transmission