Data backup security in cloud storage system

OpenAIRE

Атаян, Борис Геннадьевич; Национальный политехнический университет Армении; Багдасарян, Татевик Араевна; Национальный политехнический университет Армении

2016-01-01

Cloud backup system is proposed, which provides means for effective creation, secure storage and restore of backups inCloud. For data archiving new efficient SGBP file format is being used in the system, which is based on DEFLATE compressionalgorithm. Proposed format provides means for fast archive creation, which can contain significant amounts of data. Modernapproaches of backup archive protection are described in the paper. Also the SGBP format is compared to heavily used ZIP format(both Z...

Estimating the Backup Reaction Wheel Orientation Using Reaction Wheel Spin Rates Flight Telemetry from a Spacecraft

Science.gov (United States)

Rizvi, Farheen

2013-01-01

A report describes a model that estimates the orientation of the backup reaction wheel using the reaction wheel spin rates telemetry from a spacecraft. Attitude control via the reaction wheel assembly (RWA) onboard a spacecraft uses three reaction wheels (one wheel per axis) and a backup to accommodate any wheel degradation throughout the course of the mission. The spacecraft dynamics prediction depends upon the correct knowledge of the reaction wheel orientations. Thus, it is vital to determine the actual orientation of the reaction wheels such that the correct spacecraft dynamics can be predicted. The conservation of angular momentum is used to estimate the orientation of the backup reaction wheel from the prime and backup reaction wheel spin rates data. The method is applied in estimating the orientation of the backup wheel onboard the Cassini spacecraft. The flight telemetry from the March 2011 prime and backup RWA swap activity on Cassini is used to obtain the best estimate for the backup reaction wheel orientation.

Backup in Windows 8

CERN Document Server

Steps, Studio Visual

2014-01-01

Creating backups (or safety copies) of files has become increasingly important for many computer users. A growing number of people save important and vital information on their computer. Often this will be business, tax or financial information, but it also can include photos and videos. Nowadays, lots of fond memories and unforgettable moments are recorded onto digital media with photo and video cameras. A few years ago backups were usually created on storage media such as floppy disks, CDs, or DVDs. These types of storage media had one major disadvantage, in that you could only store a s

Backup in Windows 7

CERN Document Server

2014-01-01

Creating backups (or safety copies) of files has become increasingly important for many computer users. A growing number of people save important and vital information on their computer. Often this will be business, tax or financial information, but it also can include photos and videos. Nowadays, lots of fond memories and unforgettable moments are recorded onto digital media with photo and video cameras. A few years ago backups were usually created on storage media such as floppy disks, CDs, or DVDs. These types of storage media had one major disadvantage, in that you could only store a s

Relative tracking control of constellation satellites considering inter-satellite link

Science.gov (United States)

Fakoor, M.; Amozegary, F.; Bakhtiari, M.; Daneshjou, K.

2017-11-01

In this article, two main issues related to the large-scale relative motion of satellites in the constellation are investigated to establish the Inter Satellite Link (ISL) which means the dynamic and control problems. In the section related to dynamic problems, a detailed and effective analytical solution is initially provided for the problem of satellite relative motion considering perturbations. The direct geometric method utilizing spherical coordinates is employed to achieve this solution. The evaluation of simulation shows that the solution obtained from the geometric method calculates the relative motion of the satellite with high accuracy. Thus, the proposed analytical solution will be applicable and effective. In the section related to control problems, the relative tracking control system between two satellites will be designed in order to establish a communication link between the satellites utilizing analytical solution for relative motion of satellites with respect to the reference trajectory. Sliding mode control approach is employed to develop the relative tracking control system for body to body and payload to payload tracking control. Efficiency of sliding mode control approach is compared with PID and LQR controllers. Two types of payload to payload tracking control considering with and without payload degree of freedom are designed and suitable one for practical ISL applications is introduced. Also, Fuzzy controller is utilized to eliminate the control input in the sliding mode controller.

Site initialization, recovery, and back-up in a distributed database system

International Nuclear Information System (INIS)

Attar, R.; Bernstein, P.A.; Goodman, N.

1982-01-01

Site initialization is the problem of integrating a new site into a running distributed database system (DDBS). Site recovery is the problem of integrating an old site into a DDBS when the site recovers from failure. Site backup is the problem of creating a static backup copy of a database for archival or query purposes. We present an algorithm that solves the site initialization problem. By modifying the algorithm slightly, we get solutions to the other two problems as well. Our algorithm exploits the fact that a correct DDBS must run a serializable concurrency control algorithm. Our algorithm relies on the concurrency control algorithm to handle all inter-site synchronization

Backup power sources for DOE facilities

Energy Technology Data Exchange (ETDEWEB)

1994-09-01

This standard establishes fundamental requirements and guidance for backup power sources at DOE facilities. Purpose is to document good engineering practices for installation, testing, and maintenance of these backup power sources, which also covers emergency power sources. Examples are those which supply power to nuclear safety systems, radiation monitors and alarms, fire protection systems, security systems, and emergency lighting.

Applying secret sharing for HIS backup exchange.

Science.gov (United States)

Kuroda, Tomohiro; Kimura, Eizen; Matsumura, Yasushi; Yamashita, Yoshinori; Hiramatsu, Haruhiko; Kume, Naoto; Sato, Atsushi

2013-01-01

To secure business continuity is indispensable for hospitals to fulfill its social responsibility under disasters. Although to back up the data of the hospital information system (HIS) at multiple remote sites is a key strategy of business continuity plan (BCP), the requirements to treat privacy sensitive data jack up the cost for the backup. The secret sharing is a method to split an original secret message up so that each individual piece is meaningless, but putting sufficient number of pieces together to reveal the original message. The secret sharing method eases us to exchange HIS backups between multiple hospitals. This paper evaluated the feasibility of the commercial secret sharing solution for HIS backup through several simulations. The result shows that the commercial solution is feasible to realize reasonable HIS backup exchange platform when template of contract between participating hospitals is ready.

Comparison of Cloud backup performance and costs in Oracle database

Directory of Open Access Journals (Sweden)

Aljaž Zrnec

2011-06-01

Full Text Available Normal 0 21 false false false SL X-NONE X-NONE Current practice of backing up data is based on using backup tapes and remote locations for storing data. Nowadays, with the advent of cloud computing a new concept of database backup emerges. The paper presents the possibility of making backup copies of data in the cloud. We are mainly focused on performance and economic issues of making backups in the cloud in comparison to traditional backups. We tested the performance and overall costs of making backup copies of data in Oracle database using Amazon S3 and EC2 cloud services. The costs estimation was performed on the basis of the prices published on Amazon S3 and Amazon EC2 sites.

Satellite Communications for ATM

Science.gov (United States)

Shamma, Mohammed A.

2003-01-01

This presentation is an overview on Satellite Communication for the Aeronautical Telecommunication Management (ATM) research. Satellite Communications are being considered by the FAA and NASA as a possible alternative to the present and future ground systems supporting Air Traffic Communications. The international Civil Aviation Organization (ICAO) have in place Standards and Recommended Practices (SARPS) for the Aeronautical Mobile Satellite Services (AMSS) which is mainly derived from the pre-existing Inmarsat service that has been in service since the 1980s. The Working Group A of the Aeronautical Mobile Communication Panel of ICAO has also been investigating SARPS for what is called the Next Generation Satellite Service (NGSS) which conforms less to the Inmarsat based architecture and explores wider options in terms of satellite architectures. Several designs are being proposed by Firms such as Boeing, ESA, NASA that are geared toward full or secondary usage of satellite communications for ATM. Satellite communications for ATM can serve several purposes ranging from primary usage where ground services would play a minimal backup role, to an integrated solution where it will be used to cover services, or areas that are less likely to be supported by the proposed and existing ground infrastructure. Such Integrated roles can include usage of satellite communications for oceanic and remote land areas for example. It also can include relieving the capacity of the ground network by providing broadcast based services of Traffic Information Services messages (TIS-B), or Flight Information Services (FIS-B) which can take a significant portion of the ground system capacity. Additionally, satellite communication can play a backup role to support any needs for ground replacement, or additional needed capacity even after the new digital systems are in place. The additional bandwidth that can be provided via satellite communications can also open the door for many new

Backup Sourcing Decisions for Coping with Supply Disruptions under Long-Term Horizons

Directory of Open Access Journals (Sweden)

Jing Hou

2016-01-01

Full Text Available This paper studies a buyer’s inventory control problem under a long-term horizon. The buyer has one major supplier that is prone to disruption risks and one backup supplier with higher wholesale price. Two kinds of sourcing methods are available for the buyer: single sourcing with/without contingent supply and dual sourcing. In contingent sourcing, the backup supplier is capacitated and/or has yield uncertainty, whereas in dual sourcing the backup supplier has an incentive to offer output flexibility during disrupted periods. The buyer’s expected cost functions and the optimal base-stock levels using each sourcing method under long-term horizon are obtained, respectively. The effects of three risk parameters, disruption probability, contingent capacity or uncertainty, and backup flexibility, are examined using comparative studies and numerical computations. Four sourcing methods, namely, single sourcing with contingent supply, dual sourcing, and single sourcing from either of the two suppliers, are also compared. These findings can be used as a valuable guideline for companies to select an appropriate sourcing strategy under supply disruption risks.

Comparison of Cloud vs. Tape Backup Performance and Costs with Oracle Database

OpenAIRE

Zrnec, Aljaž; Lavbič, Dejan

2011-01-01

Current practice of backing up data is based on using backup tapes and remote locations for storing data. Nowadays, with the advent of cloud computing a new concept of database backup emerges. The paper presents the possibility of making backup copies of data in the cloud. We are mainly focused on performance and economic issues of making backups in the cloud in comparison to traditional backups. We tested the performance and overall costs of making backup copies of data in Ora...

Backup flexibility classes in emerging large-scale renewable electricity systems

International Nuclear Information System (INIS)

Schlachtberger, D.P.; Becker, S.; Schramm, S.; Greiner, M.

2016-01-01

Highlights: • Flexible backup demand in a European wind and solar based power system is modelled. • Three flexibility classes are defined based on production and consumption timescales. • Seasonal backup capacities are shown to be only used below 50% renewable penetration. • Large-scale transmission between countries can reduce fast flexible capacities. - Abstract: High shares of intermittent renewable power generation in a European electricity system will require flexible backup power generation on the dominant diurnal, synoptic, and seasonal weather timescales. The same three timescales are already covered by today’s dispatchable electricity generation facilities, which are able to follow the typical load variations on the intra-day, intra-week, and seasonal timescales. This work aims to quantify the changing demand for those three backup flexibility classes in emerging large-scale electricity systems, as they transform from low to high shares of variable renewable power generation. A weather-driven modelling is used, which aggregates eight years of wind and solar power generation data as well as load data over Germany and Europe, and splits the backup system required to cover the residual load into three flexibility classes distinguished by their respective maximum rates of change of power output. This modelling shows that the slowly flexible backup system is dominant at low renewable shares, but its optimized capacity decreases and drops close to zero once the average renewable power generation exceeds 50% of the mean load. The medium flexible backup capacities increase for modest renewable shares, peak at around a 40% renewable share, and then continuously decrease to almost zero once the average renewable power generation becomes larger than 100% of the mean load. The dispatch capacity of the highly flexible backup system becomes dominant for renewable shares beyond 50%, and reach their maximum around a 70% renewable share. For renewable shares

Agent control of cooperating satellites

OpenAIRE

Lincoln, N.K.; Veres, S.M.; Dennis, Louise; Fisher, Michael; Lisitsa, Alexei

2011-01-01

A novel, hybrid, agent architecture for (small)swarms of satellites has been developed. The software architecture for each satellite comprises ahigh-level rational agent linked to a low-level control system. The rational agent forms dynamicgoals, decides how to tackle them and passes theactual implementation of these plans to the control layer. The rational agent also has access to aMatLabmodel of the satellite dynamics, thus allowing it to carry out selective hypothetical reasoningabout pote...

Gigabit Satellite Network for NASA's Advanced Communication Technology Satellite (ACTS)

Science.gov (United States)

Hoder, Douglas; Bergamo, Marcos

1996-01-01

The advanced communication technology satellite (ACTS) gigabit satellite network provides long-haul point-to-point and point-to-multipoint full-duplex SONET services over NASA's ACTS. at rates up to 622 Mbit/s (SONET OC-12), with signal quality comparable to that obtained with terrestrial fiber networks. Data multiplexing over the satellite is accomplished using time-division multiple access (TDMA) techniques coordinated with the switching and beam hopping facilities provided by ACTS. Transmissions through the satellite are protected with Reed-Solomon encoding. providing virtually error-free transmission under most weather conditions. Unique to the system are a TDMA frame structure and satellite synchronization mechanism that allow: (a) very efficient utilization of the satellite capacity: (b) over-the-satellite dosed-loop synchronization of the network in configurations with up to 64 ground stations: and (c) ground station initial acquisition without collisions with existing signalling or data traffic. The user interfaces are compatible with SONET standards, performing the function of conventional SONET multiplexers and. as such. can be: readily integrated with standard SONET fiber-based terrestrial networks. Management of the network is based upon the simple network management protocol (SNMP). and includes an over-the-satellite signalling network and backup terrestrial internet (IP-based) connectivity. A description of the ground stations is also included.

The near-source impacts of diesel backup generators in urban environments

Science.gov (United States)

Tong, Zheming; Zhang, K. Max

2015-05-01

Distributed power generation, located close to consumers, plays an important role in the current and future power systems. However, its near-source impacts in complex urban environments are not well understood. In this paper, we focused on diesel backup generators that participate in demand response (DR) programs. We first improved the micro-environmental air quality simulations by employing a meteorology processor, AERMET, to generate site-specific boundary layer parameters for the Large Eddy Simulation (LES) modeling. The modeling structure was then incorporated into the CTAG model to evaluate the environmental impacts of diesel backup generators in near-source microenvironments. We found that the presence of either tall upwind or downwind building can deteriorate the air quality in the near-stack street canyons, largely due to the recirculation zones generated by the tall buildings, reducing the near-stack dispersion. Decreasing exhaust momentum ratio (stack exit velocity/ambient wind velocity) draws more exhaust into the recirculation zone, and reduces the effective stack height, which results in elevated near-ground concentrations inside downwind street canyons. The near-ground PM2.5 concentration for the worst scenarios could well exceed 100 μg m-3, posing potential health risk to people living and working nearby. In general, older diesel backup generators (i.e., Tier 1, 2 or older) without the up-to-date emission control may significantly increase the pollutant concentration in the near-source street canyons if participating in DR programs. Even generators that comply with Tier-4 standards could lead to PM hotspots if their stacks are next to tall buildings. Our study implies that the siting of diesel backup generators stacks should consider not only the interactions of fresh air intake and exhaust outlet for the building housing the backup generators, but also the dispersion of exhaust plumes in the surrounding environment.

Oracle Database 12c backup and recovery survival guide

CERN Document Server

Alvarez, Francisco Munoz

2013-01-01

The book follows a tutorial-based approach, covering all the best practices for backup and recovery. The book starts by introducing readers to the world of backup and recovery, then moves on to teach them the new features offered by Oracle 12c. The book is full of useful tips and best practices that are essential for any DBA to perform backup and recovery operations in an organization.This book is designed for Oracle DBAs and system administrators. The reader will have a basic working experience of administering Oracle databases. This book is designed for Oracle DBAs and system administrators.

Reactor shutdown back-up system

International Nuclear Information System (INIS)

Hirao, Seizo; Sakashita, Motoaki.

1982-01-01

Purpose: To prevent back flow of poison upon injection to a moderator recycling pipeway. Constitution: In a nuclear reactor comprising a moderator recycling system for recycling and cooling moderator through a control rod guide pipe and a rapid poison injection system for rapidly injecting a poison solution at high density into the moderator by way of the same control rod guide pipe as a reactor shutdown back-up system, a mechanism is provided for preventing the back flow of a poison solution at high density into the moderator recycling system upon rapid injection of poison. An orifice provided in the joining pipeway to the control rod guide pipe on the side of the moderator recycling system is utilized as the back flow preventing device for the poison solution and the diameter for the orifice is determined so as to provide a constant ratio between the pressure loss in the control rod guide pipe and the pressure loss in the moderator recycling system pipe line upon usual reactor operation. (Kawakami, Y.)

The solar panels on the GOES-L satellite are deployed

Science.gov (United States)

1999-01-01

Loral workers at Astrotech, Titusville, Fla., check out the solar panels of the GOES-L weather satellite, to be launched from Cape Canaveral Air Station (CCAS) aboard an Atlas II rocket in late March. The GOES-L is the fourth of a new advanced series of geostationary weather satellites for the National Oceanic and Atmospheric Administration. It is a three-axis inertially stabilized spacecraft that will provide pictures and perform atmospheric sounding at the same time. Once launched, the satellite, to be designated GOES-11, will undergo checkout and provide backup capabilities for the existing, aging GOES East weather satellite.

30 CFR 75.1101-9 - Back-up water system.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Back-up water system. 75.1101-9 Section 75.1101-9 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Fire Protection § 75.1101-9 Back-up water system...

Satellite Control Laboratory

DEFF Research Database (Denmark)

Wisniewski, Rafal; Bak, Thomas

2001-01-01

The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft......-axis magnetometer, three piezoelectric gyros, and four reaction wheels in a tetrahedron configuration. The operation of the spacecraft is fully autonomous. The data flow between the transducers and the onboard computer placed physically outside the satellite is provided by a radio link. The purpose...... can be implemented in the laboratory, e.g. three-axis attitude control, slew manoeuvres, spins stabilization using magnetic actuation and/or reaction wheels. The spacecraft attitude can be determined applying magnetometer measurements....

Satellite Attitude Control System Simulator

Directory of Open Access Journals (Sweden)

G.T. Conti

2008-01-01

Full Text Available Future space missions will involve satellites with great autonomy and stringent pointing precision, requiring of the Attitude Control Systems (ACS with better performance than before, which is function of the control algorithms implemented on board computers. The difficulties for developing experimental ACS test is to obtain zero gravity and torque free conditions similar to the SCA operate in space. However, prototypes for control algorithms experimental verification are fundamental for space mission success. This paper presents the parameters estimation such as inertia matrix and position of mass centre of a Satellite Attitude Control System Simulator (SACSS, using algorithms based on least square regression and least square recursive methods. Simulations have shown that both methods have estimated the system parameters with small error. However, the least square recursive methods have performance more adequate for the SACSS objectives. The SACSS platform model will be used to do experimental verification of fundamental aspects of the satellite attitude dynamics and design of different attitude control algorithm.

Fuel Cells for Backup Power in Telecommunications Facilities (Fact Sheet)

Energy Technology Data Exchange (ETDEWEB)

2009-04-01

Telecommunications providers rely on backup power to maintain a constant power supply, to prevent power outages, and to ensure the operability of cell towers, equipment, and networks. The backup power supply that best meets these objectives is fuel cell technology.

Production planning and backup sourcing strategy of a buyer-dominant supply chain with random yield and demand

Science.gov (United States)

Chen, Kebing; Xiao, Tiaojun

2015-11-01

This paper studies the backup sourcing strategy of the buyer and the production planning of the supplier in presence of both random yield and random demand. Since the production is susceptible to the randomness of yield beyond the control of the supplier, the buyer may access to a backup sourcing option for the finished items. We analyse the value of backup sourcing for both the decentralised and centralised channels. Backup sourcing strategy of the buyer may lower the supply chain's performance. We show that the order quantity of the buyer does not change the stocking factor of the supplier's input. Meanwhile, compared with the centralised operation, the decentralised operation is more dependent on the backup sourcing to reduce supply shortage of the contracting supplier. From the channel's perspective, an incentive scheme is developed to facilitate the coordination of both the buyer and the contracting supplier, we show that the proposed option contract can allow the supply chain members to share the respective risks involved in the production and selling processes. Finally, we also provide qualitative insights based on numerical examples of the centralised and decentralised solutions.

STS-9 payload specialists and backup in training session

Science.gov (United States)

1983-01-01

Two Spacelab 1 payload specialists and a backup for that flight prepare for a training session in the JSC mockup and integration laboratory. Fully decked out in the Shuttle constant wear garments (foreground) are Ulf Merbold, left, and Byron K. Licktenberg, prime crewmembers on the STS-9 team. In civilian clothes is payload specialist backup Michael L. Lampton.

Hydrogen Fuel Cell Performance as Telecommunications Backup Power in the United States

Energy Technology Data Exchange (ETDEWEB)

Kurtz, Jennifer [National Renewable Energy Lab. (NREL), Golden, CO (United States); Saur, Genevieve [National Renewable Energy Lab. (NREL), Golden, CO (United States); Sprik, Sam [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2015-03-01

Working in collaboration with the U.S. Department of Energy (DOE) and industry project partners, the National Renewable Energy Laboratory (NREL) acts as the central data repository for the data collected from real-world operation of fuel cell backup power systems. With American Recovery and Reinvestment Act of 2009 (ARRA) co-funding awarded through DOE's Fuel Cell Technologies Office, more than 1,300 fuel cell units were deployed over a three-plus-year period in stationary, material handling equipment, auxiliary power, and backup power applications. This surpassed a Fuel Cell Technologies Office ARRA objective to spur commercialization of an early market technology by installing 1,000 fuel cell units across several different applications, including backup power. By December 2013, 852 backup power units out of 1,330 fuel cell units deployed were providing backup service, mainly for telecommunications towers. For 136 of the fuel cell backup units, project participants provided detailed operational data to the National Fuel Cell Technology Evaluation Center for analysis by NREL's technology validation team. NREL analyzed operational data collected from these government co-funded demonstration projects to characterize key fuel cell backup power performance metrics, including reliability and operation trends, and to highlight the business case for using fuel cells in these early market applications. NREL's analyses include these critical metrics, along with deployment, U.S. grid outage statistics, and infrastructure operation.

Models for dynamic analysis of backup ball bearings of an AMB-system

Science.gov (United States)

Halminen, Oskari; Aceituno, Javier F.; Escalona, José L.; Sopanen, Jussi; Mikkola, Aki

2017-10-01

Two detailed models of backup bearing are introduced for dynamic analysis of the dropdown event of a rotor supported by an active magnetic bearing (AMB). The proposed two-dimensional models of the backup bearings are based on a multibody approach. All parts of the bearing are modeled as rigid bodies with geometrical surfaces and the bodies interact with each other through contact forces. The first model describes a backup bearing without a cage, and the second model describes a backup bearing with a cage. The introduced models, which incorporate a realistic elastic contact model, are compared with previously presented simplified models through parametric study. In order to ensure the durability of backup bearings in challenging applications where ball bearings with an oversized bore are necessary, analysis of the forces affecting the bearing's cage and balls is required, and the models introduced in this work assist in this task as they enable optimal properties for the bearing's cage and balls to be found.

Satellite Attitude Control Using Only Electromagnetic Actuation

DEFF Research Database (Denmark)

Wisniewski, Rafal

when a satellite is on a throughout this thesis. Confined computer capacity and a limit on electrical power supply were separate obstacles.They demanded computational simplicity and power optimality from the attitude control system. The design of quasi optimal controllers for a real-time implementation...... to provide four stable equilibria, one of which was the desired orientation. It was explained how the equilibria depended on the ratio of the satellite's moments of inertia. It was further investigated how to control the attitude, such that the satellite was globally asymptotically stable in the desired...

Satellite cluster flight using on-off cyclic control

Science.gov (United States)

Zhang, Hao; Gurfil, Pini

2015-01-01

Nano-satellite clusters and disaggregated satellites are new concepts in the realm of distributed satellite systems, which require complex cluster management - mainly regulating the maximal and minimal inter-satellite distances on time scales of years - while utilizing simple on-off propulsion systems. The simple actuators and long time scales require judicious astrodynamical modeling coupled with specialized orbit control. This paper offers a satellite cluster orbit control law which works for long time scales in a perturbed environment while utilizing fixed-magnitude thrusters. The main idea is to design a distributed controller which balances the fuel consumption among the satellites, thus mitigating the effect of differential drag perturbations. The underlying methodology utilizes a cyclic control algorithm based on a mean orbital elements feedback. Stability properties of the closed-loop cyclic control system do not adhere to the classical Lyapunov stability theory, so an effort is made to define and implement a suitable stability theory of noncompact equilibria sets. A state selection scheme is proposed for efficiently establishing a low Earth orbit cluster. Several simulations, including a real mission study, and several comparative investigations, are performed to show the strengths of the proposed control law.

Researching, Evaluating, and Choosing a Backup Service in the Cloud

Science.gov (United States)

Hastings, Robin

2012-01-01

Backups are a modern fact of life. Every organization that has any kind of computing technology (and that is all of them these days) needs to back up its data in case of technological or user errors. Traditionally, large-scale backups have been done via an internal or external tape drive that takes magnetic tapes (minicassettes, essentially) and…

A Survey on Backup of Data on Remote Server

OpenAIRE

Raje, Manali; Mukhopadhyay, Debajyoti

2015-01-01

Large amount of electronic data is generated in Cloud computing every day. Efficient maintenance of this data requires proper services. Hence a method to collect data securely, by protecting and developing backups is mentioned. The Objective is to provide Auto Response Server, better solutions for data backup and restoring using Cloud. Data can be collected and sent to a centralized repository in a platform independent format without any network consideration. This data can then be used accor...

RAICS AS ADVANCED CLOUD BACKUP TECHNOLOGY IN TELECOMMUNICATION NETWORKS

OpenAIRE

Luntovskyy, Andriy; Vasyutynskyy, Volodymyr; Spillner, Josef

2014-01-01

Data crashes can cause unpredictable and even hard-out effects for an enterprise or authority. Backup strategies as antidote uni-fy a complex of organizational and technical measures that are necessary for data restoring, processing and transfer as well as for data security and defense against its loss, crash and tampering. High-performance modern Internet allows delivery of back-up functions and is complemented by attractive (mobile) services with a Quality of Service comparable to that in L...

The depth of the honeybee's backup sun-compass systems.

Science.gov (United States)

Dovey, Katelyn M; Kemfort, Jordan R; Towne, William F

2013-06-01

Honeybees have at least three compass mechanisms: a magnetic compass; a celestial or sun compass, based on the daily rotation of the sun and sun-linked skylight patterns; and a backup celestial compass based on a memory of the sun's movements over time in relation to the landscape. The interactions of these compass systems have yet to be fully elucidated, but the celestial compass is primary in most contexts, the magnetic compass is a backup in certain contexts, and the bees' memory of the sun's course in relation to the landscape is a backup system for cloudy days. Here we ask whether bees have any further compass systems, for example a memory of the sun's movements over time in relation to the magnetic field. To test this, we challenged bees to locate the sun when their known celestial compass systems were unavailable, that is, under overcast skies in unfamiliar landscapes. We measured the bees' knowledge of the sun's location by observing their waggle dances, by which foragers indicate the directions toward food sources in relation to the sun's compass bearing. We found that bees have no celestial compass systems beyond those already known: under overcast skies in unfamiliar landscapes, bees attempt to use their landscape-based backup system to locate the sun, matching the landscapes or skylines at the test sites with those at their natal sites as best they can, even if the matches are poor and yield weak or inconsistent orientation.

Improving the Quality of Backup Process for Publishing Houses and Printing Houses

Science.gov (United States)

Proskuriakov, N. E.; Yakovlev, B. S.; Pries, V. V.

2018-04-01

The analysis of main types for data threats, used by print media, and their influence on the vitality and security of information is made. The influence of the programs settings for preparing archive files, the types of file managers on the backup process is analysed. We proposed a simple and economical version of the practical implementation of the backup process consisting of 4 components: the command line interpreter, the 7z archiver, the Robocopy utility, and network storage. We recommend that the best option would be to create backup copies, consisting of three local copies of data and two network copies.

Programming a real-time operating system for satellite control applications Satellite Control Applications

International Nuclear Information System (INIS)

Omer, M.; Anjum, O.; Suddle, M.R.

2004-01-01

With the realization of ideas like formation flights and multi-body space vehicles the demands on an attitude control system have become increasingly complex. Even in its most simplified form, the control system for a typical geostationary satellite has to run various supervisory functions along with determination and control algorithms side by side. Within each algorithm it has to employ multiple actuation and sensing mechanisms and service real time interrupts, for example, in the case of actuator saturation and sensor data fusion. This entails the idea of thread scheduling and program synchronization, tasks specifically meant for a real time OS. This paper explores the embedding of attitude determination and control loop within the framework of a real time operating system provided for TI's DSP C6xxx series. The paper details out the much functionality provided within the scaleable real time kernel and the analysis and configuration tools available, It goes on to describe a layered implementation stack associated with a typical control for Geo Stationary satellites. An application for control is then presented in which state of the art analysis tools are employed to view program threads, synchronization semaphores, hardware interrupts and data exchange pipes operating in real time. (author)

A hybrid data compression approach for online backup service

Science.gov (United States)

Wang, Hua; Zhou, Ke; Qin, MingKang

2009-08-01

With the popularity of Saas (Software as a service), backup service has becoming a hot topic of storage application. Due to the numerous backup users, how to reduce the massive data load is a key problem for system designer. Data compression provides a good solution. Traditional data compression application used to adopt a single method, which has limitations in some respects. For example data stream compression can only realize intra-file compression, de-duplication is used to eliminate inter-file redundant data, compression efficiency cannot meet the need of backup service software. This paper proposes a novel hybrid compression approach, which includes two levels: global compression and block compression. The former can eliminate redundant inter-file copies across different users, the latter adopts data stream compression technology to realize intra-file de-duplication. Several compressing algorithms were adopted to measure the compression ratio and CPU time. Adaptability using different algorithm in certain situation is also analyzed. The performance analysis shows that great improvement is made through the hybrid compression policy.

Modeling and control of a gravity gradient stabilised satellite

Directory of Open Access Journals (Sweden)

Aage Skullestad

1999-01-01

Full Text Available This paper describes attitude control, i.e., 3-axes stabilisation and pointing, of a proposed Norwegian small gravity gradient stabilized satellite to be launched into low earth orbit. Generally, a gravity gradient stabilised system has limited stability and pointing capabilities, and wheels and/or magnetic coils are added in order to improve the attitude control. The best attitude accuracy is achieved using wheels, which can give accuracies down to less than one degree, but wheels increase the complexity and cost of the satellite. Magnetic coils allow cheaper satellites, and are an attractive solution to small, inexpensive satellites in low earth orbits and may provide an attitude control accuracy of a few degrees. Scientific measurements often require accurate attitude control in one or two axes only. Combining wheel and coil control may, in these cases, provide the best solutions. The simulation results are based on a linearised mathematical model of the satellite.

Empirical Analysis of High Efficient Remote Cloud Data Center Backup Using HBase and Cassandra

Directory of Open Access Journals (Sweden)

Bao Rong Chang

2015-01-01

Full Text Available HBase, a master-slave framework, and Cassandra, a peer-to-peer (P2P framework, are the two most commonly used large-scale distributed NoSQL databases, especially applicable to the cloud computing with high flexibility and scalability and the ease of big data processing. Regarding storage structure, different structure adopts distinct backup strategy to reduce the risks of data loss. This paper aims to realize high efficient remote cloud data center backup using HBase and Cassandra, and in order to verify the high efficiency backup they have applied Thrift Java for cloud data center to take a stress test by performing strictly data read/write and remote database backup in the large amounts of data. Finally, in terms of the effectiveness-cost evaluation to assess the remote datacenter backup, a cost-performance ratio has been evaluated for several benchmark databases and the proposed ones. As a result, the proposed HBase approach outperforms the other databases.

Control of the Tevatron Satellite Refrigeration system

International Nuclear Information System (INIS)

Theilacker, J.; Chapman, L.; Gannon, J.; Hentges, M.; Martin, M.; Rode, C.H.; Zagel, J.

1984-01-01

This chapter describes a computerized control system for 24 satellite refrigerators which cool a six kilometer ring of superconducting magnets. The control system consists of 31 independent microprocessors operating over 400 servo loops, and a central computer system which provides monitoring, alarms, logging and changing of parameters. Topics considered include pressure measurement, flow measurement, temperature measurement, gas analysis, control valves, expansion engine controllers, and control loops. Each refrigerator has 12 active microprocessor based control loops which tune the refrigerator to one of its four operating modes: satellite, liquefier, refrigerator, and stand-by. It is suggested that optimizing the refrigerator control loops and quench recovery scheme will minimize the accelerator down time

Research and implementation of PC data synchronous backup based on cloud computing

Directory of Open Access Journals (Sweden)

WU Yu

2013-08-01

Full Text Available In order to better ensure data security，data integrity，and facilitate remote management，this paper has designed and implemented a system model for PC data synchronous backup from the view of the local database and personal data． It focuses on the data backup and uses SQL Azure( a cloud database management system and Visual Studio( a development platform tool ． Also the system is released and deployed on the Windows Azure Platform with a unique web portal． Experimental tests show that compared to other data backup methods in non-cloud environment，the system has certain advantages and research value on mobility，interoperability and data management．

The challenge of localizing vehicle backup alarms: Effects of passive and electronic hearing protectors, ambient noise level, and backup alarm spectral content

Directory of Open Access Journals (Sweden)

Khaled A Alali

2011-01-01

Full Text Available A human factors experiment employed a hemi-anechoic sound field in which listeners were required to localize a vehicular backup alarm warning signal (both a standard and a frequency-augmented alarm in 360-degrees azimuth in pink noise of 60 dBA and 90 dBA. Measures of localization performance included: (1 percentage correct localization, (2 percentage of right--left localization errors, (3 percentage of front-rear localization errors, and (4 localization absolute deviation in degrees from the alarm′s actual location. In summary, the data demonstrated that, with some exceptions, normal hearing listeners′ ability to localize the backup alarm in 360-degrees azimuth did not improve when wearing augmented hearing protectors (including dichotic sound transmission earmuffs, flat attenuation earplugs, and level-dependent earplugs as compared to when wearing conventional passive earmuffs or earplugs of the foam or flanged types. Exceptions were that in the 90 dBA pink noise, the flat attenuation earplug yielded significantly better accuracy than the polyurethane foam earplug and both the dichotic and the custom-made diotic electronic sound transmission earmuffs. However, the flat attenuation earplug showed no benefit over the standard pre-molded earplug, the arc earplug, and the passive earmuff. Confusions of front-rear alarm directions were most significant in the 90 dBA noise condition, wherein two types of triple-flanged earplugs exhibited significantly fewer front-rear confusions than either of the electronic muffs. On all measures, the diotic sound transmission earmuff resulted in the poorest localization of any of the protectors due to the fact that its single-microphone design did not enable interaural cues to be heard. Localization was consistently more degraded in the 90 dBA pink noise as compared with the relatively quiet condition of the 60 dBA pink noise. A frequency-augmented backup alarm, which incorporated 400 Hz and 4000 Hz components

Satellite Formation Control Using Atmospheric Drag

National Research Council Canada - National Science Library

Hajovsky, Blake B

2007-01-01

This study investigates the use of a linear quadratic terminal controller to reconfigure satellite formations using atmospheric drag actuated control while minimizing the loss of energy of the formation...

Study of Info backup system of strategy management for coal enterprises

Energy Technology Data Exchange (ETDEWEB)

Han, K.; Dai, B.; Li, Q.; Shao, J. [China University of Mining and Technology, Xuzhou (China). College of Mineral and Energy Resources

2001-09-01

It is an application system which helps the determination, enforcement and control of the development strategy of a coal enterprise. This system, which is based on Delphi 5.0, is a Windows application and is bundled with some excellent software, such as 3D Studio Max, Autocad, PhotoShop, Gif Gear etc. It comprises of two subsystems, i.e., the information backup subsystem of strategy management and the control subsystem of strategy enforcement. This system can provide not only the effective information to the leaders or the managers, but also the timely and effective control in the whole course of strategy enforcement. 5 refs.,1 fig.

Satellite Control Laboratory

DEFF Research Database (Denmark)

Wisniewski, Rafal; Bak, Thomas

2001-01-01

The Satellite Laboratory at the Department of Control Engineering of Aalborg University (SatLab) is a dynamic motion facility designed for analysis and test of micro spacecraft. A unique feature of the laboratory is that it provides a completely gravity-free environment. A test spacecraft...... of the laboratory is to conduct dynamic tests of the control and attitude determination algorithms during nominal operation and in abnormal conditions. Further it is intended to use SatLab for validation of various algorithms for fault detection, accommodation and supervisory control. Different mission objectives...... can be implemented in the laboratory, e.g. three-axis attitude control, slew manoeuvres, spins stabilization using magnetic actuation and/or reaction wheels. The spacecraft attitude can be determined applying magnetometer measurements...

Achieving safety/risk goals for less ATR backup power upgrades

International Nuclear Information System (INIS)

Atkinson, S.A.

1995-01-01

The Advanced Test Reactor probabilistic risk assessment for internal fire and flood events defined a relatively high risk for a total loss of electric power possibly leading to core damage. Backup power sources were disabled due to fire and flooding in the diesel generator area with propagation of the flooding to a common switchgear room. The ATR risk assessment was employed to define options for relocation of backup power system components to achieve needed risk reduction while minimizing costs. The risk evaluations were performed using sensitivity studies and importance measures. The risk-based evaluations of relocation options for backup power systems saved over $3 million from what might have been otherwise considered open-quotes necessaryclose quotes for safety/risk improvement. The ATR experience shows that the advantages of a good risk assessment are to define risk significance, risk specifics, and risk solutions which enable risk goals to be achieved at the lowest cost

Communication satellites to enter a new age of flexibility

Science.gov (United States)

Balty, Cédric; Gayrard, Jean-Didier; Agnieray, Patrick

2009-07-01

To cope with the economical and technical evolutions of the communication market and to better compete with or complement terrestrial networks, satellite operators are requiring more flexible satellites. It allows a better fleet planning potential and back-up policy, a more standardized and efficient procurement process, mission adaptation to market evolution and the possibility of early entry in new markets. New technologies that are developed either for terrestrial networks or for space defense applications would become soon available to satellite and equipment manufacturers. A skilful mix of these new technologies with the older and more mature ones should boost satellite performances and bring flexibility to the new generation of communication satellites. This paper reviews the economical and technical environment of the space communication business for the next decade. It identifies the needs and levels of flexibility that are required by the market but also allowed by technologies, in both a top-down and bottom-up approach.

Piloted Simulation Tests of Propulsion Control as Backup to Loss of Primary Flight Controls for a B747-400 Jet Transport

Science.gov (United States)

Bull, John; Mah, Robert; Hardy, Gordon; Sullivan, Barry; Jones, Jerry; Williams, Diane; Soukup, Paul; Winters, Jose

1997-01-01

Partial failures of aircraft primary flight control systems and structural damages to aircraft during flight have led to catastrophic accidents with subsequent loss of lives (e.g. DC-10, B-747, C-5, B-52, and others). Following the DC-10 accident at Sioux City, Iowa in 1989, the National Transportation Safety Board recommended 'Encourage research and development of backup flight control systems for newly certified wide-body airplanes that utilize an alternate source of motive power separate from that source used for the conventional control system.' This report describes the concept of a propulsion controlled aircraft (PCA), discusses pilot controls, displays, and procedures; and presents the results of a PCA piloted simulation test and evaluation of the B747-400 airplane conducted at NASA Ames Research Center in December, 1996. The purpose of the test was to develop and evaluate propulsion control throughout the full flight envelope of the B747-400 including worst case scenarios of engine failures and out of trim moments. Pilot ratings of PCA performance ranged from adequate to satisfactory. PCA performed well in unusual attitude recoveries at 35,000 ft altitude, performed well in fully coupled ILS approaches, performed well in single engine failures, and performed well at aft cg. PCA performance was primarily limited by out-of-trim moments.

Hardware in the loop simulation test platform of fuel cell backup system

Directory of Open Access Journals (Sweden)

Ma Tiancai

2015-01-01

Full Text Available Based on an analysis of voltage mechanistic model, a real-time simulation model of the proton exchange membrane (PEM fuel cell backup system is developed, and verified by the measurable experiment data. The method of online parameters identification for the model is also improved. Based on the software LabVIEW/VeriStand real-time environment and the PXI Express hardware system, the PEM fuel cell system controller hardware in the loop (HIL simulation plat-form is established. Controller simulation test results showed the accuracy of HIL simulation platform.

Sliding Mode Attitude Control for Magnetic Actuated Satellite

DEFF Research Database (Denmark)

Wisniewski, Rafal

1998-01-01

control torques can only be generated perpendicular to the local geomagnetic field vector. This has been a serious obstacle for using magnetorquer based control for three-axis attitude control. This paper deals with three-axis stabilization of a low earth orbit satellite. The problem of controlling...... the spacecraft attitude using only magnetic torquing is realized in the form of the sliding mode control. A three dimensional sliding manifold is proposed, and it is shown that the satellite motion on the sliding manifold is asymptotically stable...

Fuel Cell Backup Power System for Grid Service and Micro-Grid in Telecommunication Applications: Preprint

Energy Technology Data Exchange (ETDEWEB)

Ma, Zhiwen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Eichman, Joshua D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kurtz, Jennifer M [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-03-22

This paper presents the feasibility and economics of using fuel cell backup power systems in telecommunication cell towers to provide grid services (e.g., ancillary services, demand response). The fuel cells are able to provide power for the cell tower during emergency conditions. This study evaluates the strategic integration of clean, efficient, and reliable fuel cell systems with the grid for improved economic benefits. The backup systems have potential as enhanced capability through information exchanges with the power grid to add value as grid services that depend on location and time. The economic analysis has been focused on the potential revenue for distributed telecommunications fuel cell backup units to provide value-added power supply. This paper shows case studies on current fuel cell backup power locations and regional grid service programs. The grid service benefits and system configurations for different operation modes provide opportunities for expanding backup fuel cell applications responsive to grid needs.

Congestion control and routing over satellite networks

Science.gov (United States)

Cao, Jinhua

Satellite networks and transmissions find their application in fields of computer communications, telephone communications, television broadcasting, transportation, space situational awareness systems and so on. This thesis mainly focuses on two networking issues affecting satellite networking: network congestion control and network routing optimization. Congestion, which leads to long queueing delays, packet losses or both, is a networking problem that has drawn the attention of many researchers. The goal of congestion control mechanisms is to ensure high bandwidth utilization while avoiding network congestion by regulating the rate at which traffic sources inject packets into a network. In this thesis, we propose a stable congestion controller using data-driven, safe switching control theory to improve the dynamic performance of satellite Transmission Control Protocol/Active Queue Management (TCP/AQM) networks. First, the stable region of the Proportional-Integral (PI) parameters for a nominal model is explored. Then, a PI controller, whose parameters are adaptively tuned by switching among members of a given candidate set, using observed plant data, is presented and compared with some classical AQM policy examples, such as Random Early Detection (RED) and fixed PI control. A new cost detectable switching law with an interval cost function switching algorithm, which improves the performance and also saves the computational cost, is developed and compared with a law commonly used in the switching control literature. Finite-gain stability of the system is proved. A fuzzy logic PI controller is incorporated as a special candidate to achieve good performance at all nominal points with the available set of candidate controllers. Simulations are presented to validate the theory. An effocient routing algorithm plays a key role in optimizing network resources. In this thesis, we briefly analyze Low Earth Orbit (LEO) satellite networks, review the Cross Entropy (CE

Reliability considerations of a fuel cell backup power system for telecom applications

Science.gov (United States)

Serincan, Mustafa Fazil

2016-03-01

A commercial fuel cell backup power unit is tested in real life operating conditions at a base station of a Turkish telecom operator. The fuel cell system responds to 256 of 260 electric power outages successfully, providing the required power to the base station. Reliability of the fuel cell backup power unit is found to be 98.5% at the system level. On the other hand, a qualitative reliability analysis at the component level is carried out. Implications of the power management algorithm on reliability is discussed. Moreover, integration of the backup power unit to the base station ecosystem is reviewed in the context of reliability. Impact of inverter design on the stability of the output power is outlined. Significant current harmonics are encountered when a generic inverter is used. However, ripples are attenuated significantly when a custom design inverter is used. Further, fault conditions are considered for real world case studies such as running out of hydrogen, a malfunction in the system, or an unprecedented operating scheme. Some design guidelines are suggested for hybridization of the backup power unit for an uninterrupted operation.

Satellite Dynamic Damping via Active Force Control Augmentation

Science.gov (United States)

Varatharajoo, Renuganth

2012-07-01

An approach that incorporates the Active Force Control (AFC) technique into a conventional Proportional-Derivative (PD) controller is proposed for a satellite active dynamic damping towards a full attitude control. The AFC method has been established to facilitate a robust motion control of dynamical systems in the presence of disturbances, parametric uncertainties and changes that are commonly prevalent in the real-world environment. The usefulness of the method can be extended by introducing intelligent mechanisms to approximate the mass or inertia matrix of the dynamic system to trigger the compensation effect of the controller. AFC is a technique that relies on the appropriate estimation of the inertial or mass parameters of the dynamic system and the measurements of the acceleration and force signals induced by the system if practical implementation is ever considered. In AFC, it is shown that the system subjected to a number of disturbances remains stable and robust via the compensating action of the control strategy. We demonstrate that it is possible to design a spacecraft attitude feedback controller that will ensure the system dynamics set point remains unchanged even in the presence of the disturbances provided that the actual disturbances can be modeled effectively. In order to further facilitate this analysis, a combined energy and attitude control system (CEACS) is proposed as a model satellite attitude control actuator. All the governing equations are established and the proposed satellite attitude control architecture is made amenable to numerical treatments. The results show that the PD-AFC attitude damping performances are superiorly better than that of the solely PD type. It is also shown that the tunings of the AFC system gains are crucial to ensure a better attitude damping performance and this process is mandatory for AFC systems. Finally, the results demonstrate an important satellite dynamic damping enhancement capability using the AFC

Design, analysis, and control of a large transport aircraft utilizing selective engine thrust as a backup system for the primary flight control. Ph.D. Thesis

Science.gov (United States)

Gerren, Donna S.

1995-01-01

A study has been conducted to determine the capability to control a very large transport airplane with engine thrust. This study consisted of the design of an 800-passenger airplane with a range of 5000 nautical miles design and evaluation of a flight control system, and design and piloted simulation evaluation of a thrust-only backup flight control system. Location of the four wing-mounted engines was varied to optimize the propulsive control capability, and the time constant of the engine response was studied. The goal was to provide level 1 flying qualities. The engine location and engine time constant did not have a large effect on the control capability. The airplane design did meet level 1 flying qualities based on frequencies, damping ratios, and time constants in the longitudinal and lateral-directional modes. Project pilots consistently rated the flying qualities as either level 1 or level 2 based on Cooper-Harper ratings. However, because of the limited control forces and moments, the airplane design fell short of meeting the time required to achieve a 30 deg bank and the time required to respond a control input.

Quasi Path Restoration: A post-failure recovery scheme over pre-allocated backup resource for elastic optical networks

Science.gov (United States)

Yadav, Dharmendra Singh; Babu, Sarath; Manoj, B. S.

2018-03-01

Spectrum conflict during primary and backup routes assignment in elastic optical networks results in increased resource consumption as well as high Bandwidth Blocking Probability. In order to avoid such conflicts, we propose a new scheme, Quasi Path Restoration (QPR), where we divide the available spectrum into two: (1) primary spectrum (for primary routes allocation) and (2) backup spectrum (for rerouting the data on link failures). QPR exhibits three advantages over existing survivable strategies such as Shared Path Protection (SPP), Primary First Fit Backup Last Fit (PFFBLF), Jointly Releasing and re-establishment Defragmentation SPP (JRDSSPP), and Path Restoration (PR): (1) the conflict between primary and backup spectrum during route assignment is completely eliminated, (2) upon a link failure, connection recovery requires less backup resources compared to SPP, PFFBLF, and PR, and (3) availability of the same backup spectrum on each link improves the recovery guarantee. The performance of our scheme is analyzed with different primary backup spectrum partitions on varying connection-request demands and number of frequency slots. Our results show that QPR provides better connection recovery guarantee and Backup Resources Utilization (BRU) compared to bandwidth recovery of PR strategy. In addition, we compare QPR with Shared Path Protection and Primary First-Fit Backup Last Fit strategies in terms of Bandwidth Blocking Probability (BBP) and average frequency slots per connection request. Simulation results show that BBP of SPP, PFFBLF, and JRDSPP varies between 18.59% and 14.42%, while in QPR, BBP ranges from 2.55% to 17.76% for Cost239, NSFNET, and ARPANET topologies. Also, QPR provides bandwidth recovery between 93.61% and 100%, while in PR, the recovery ranges from 86.81% to 98.99%. It is evident from our analysis that QPR provides a reasonable trade-off between bandwidth blocking probability and connection recoverability.

Design, analysis and control of large transports so that control of engine thrust can be used as a back-up of the primary flight controls. Ph.D. Thesis

Science.gov (United States)

Roskam, Jan; Ackers, Deane E.; Gerren, Donna S.

1995-01-01

A propulsion controlled aircraft (PCA) system has been developed at NASA Dryden Flight Research Center at Edwards Air Force Base, California, to provide safe, emergency landing capability should the primary flight control system of the aircraft fail. As a result of the successful PCA work being done at NASA Dryden, this project investigated the possibility of incorporating the PCA system as a backup flight control system in the design of a large, ultra-high capacity megatransport in such a way that flight path control using only the engines is not only possible, but meets MIL-Spec Level 1 or Level 2 handling quality requirements. An 800 passenger megatransport aircraft was designed and programmed into the NASA Dryden simulator. Many different analysis methods were used to evaluate the flying qualities of the megatransport while using engine thrust for flight path control, including: (1) Bode and root locus plot analysis to evaluate the frequency and damping ratio response of the megatransport; (2) analysis of actual simulator strip chart recordings to evaluate the time history response of the megatransport; and (3) analysis of Cooper-Harper pilot ratings by two NaSA test pilots.

solar dryer with biomass backup heater for drying fruits

African Journals Online (AJOL)

SOLAR DRYER WITH BIOMASS BACKUP HEATER FOR DRYING FRUITS: DEVELOPMENT AND PERFORMANCE ANALYSIS. ... Journal of Science and Technology (Ghana) ... Most solar dryers rely on only solar energy as the heat source.

ACTS TDMA network control. [Advanced Communication Technology Satellite

Science.gov (United States)

Inukai, T.; Campanella, S. J.

1984-01-01

This paper presents basic network control concepts for the Advanced Communications Technology Satellite (ACTS) System. Two experimental systems, called the low-burst-rate and high-burst-rate systems, along with ACTS ground system features, are described. The network control issues addressed include frame structures, acquisition and synchronization procedures, coordinated station burst-time plan and satellite-time plan changes, on-board clock control based on ground drift measurements, rain fade control by means of adaptive forward-error-correction (FEC) coding and transmit power augmentation, and reassignment of channel capacities on demand. The NASA ground system, which includes a primary station, diversity station, and master control station, is also described.

Emergency and backup power supplies at Department of Energy facilities: Augmented Evaluation Team -- Final report

Energy Technology Data Exchange (ETDEWEB)

1993-11-01

This report documents the results of the Defense Programs (DP) Augmented Evaluation Team (AET) review of emergency and backup power supplies (i.e., generator, uninterruptible power supply, and battery systems) at DP facilities. The review was conducted in response to concerns expressed by former Secretary of Energy James D. Watkins over the number of incidents where backup power sources failed to provide electrical power during tests or actual demands. The AET conducted a series of on-site reviews for the purpose of understanding the design, operation, maintenance, and safety significance of emergency and backup power (E&BP) supplies. The AET found that the quality of programs related to maintenance of backup power systems varies greatly among the sites visited, and often among facilities at the same site. No major safety issues were identified. However, there are areas where the AET believes the reliability of emergency and backup power systems can and should be improved. Recommendations for improving the performance of E&BP systems are provided in this report. The report also discusses progress made by Management and Operating (M&O) contractors to improve the reliability of backup sources used in safety significant applications. One area that requires further attention is the analysis and understanding of the safety implications of backup power equipment. This understanding is needed for proper graded-approach implementation of Department of Energy (DOE) Orders, and to help ensure that equipment important to the safety of DOE workers, the public, and the environment is identified, classified, recognized, and treated as such by designers, users, and maintainers. Another area considered important for improving E&BP system performance is the assignment of overall ownership responsibility and authority for ensuring that E&BP equipment performs adequately and that reliability and availability are maintained at acceptable levels.

Premature failure analysis of forged cold back-up roll in a continuous tandem mill

International Nuclear Information System (INIS)

Rad, Hamid Reza Bakhsheshi; Monshi, Ahmad; Idris, Mohd Hasbullah; Kadir, Mohammed Rafiq Abdul; Jafari, Hassan

2011-01-01

Highlights: → Metal wrapping and strip welding in work/back-up rolls contact zone caused spalling. → MnS inclusion and pore initiated crack which propagated in milling led to spalling. → Retained austenite conversion to α'-martensite accelerated spalling failure. → Needle shaped carbide (Fe,Mo,Cr) 7 C 3 , may cause poor service life of back-up roll. -- Abstract: In this paper, premature failure of a forged back-up roll from a continuous tandem mill was investigated. Microstructural evolutions of the spalled specimen and surface of the roll were characterized by optical microscopy, X-ray diffraction, scanning electron microscopy and ferritscopy, while hardness value of the specimen was measured by Vickers hardness testing. The results revealed that the presence of pore and MnS inclusion with spherical and oval morphologies were the main contributing factors responsible for the poor life of the back-up roll. In addition, metal pick up and subsequently strip welding on the surface of the work roll were found as the major causes of failure in work roll which led to spalling occurrence in the back-up roll. Furthermore, relatively high percentage of retained austenite, say 9%, in outer surface of the back-up roll contributed spalling due to conversion of this meta-stable phase to martensite and creation of volume expansion on the outer surface through work hardening during mill campaign.

An Informal Survey of the CTI Backup System

Directory of Open Access Journals (Sweden)

Joseph Covino

1981-06-01

Full Text Available In order to help decide whether or not to purchase computer backup systems from Computer Translation, Inc. (CTI, for use when the CLSI LIBS 100 automated circulation system is not operating, Great Neck Library conducted an informal survey of libraries using both systems

A Challenging Trio in Space 'Routine' Operations of the Swarm Satellite Constellation

Science.gov (United States)

Diekmann, Frank-Jurgen; Clerigo, Ignacio; Albini, Giuseppe; Maleville, Laurent; Neto, Alessandro; Patterson, David; Nino, Ana Piris; Sieg, Detlef

2016-08-01

Swarm is the first ESA Earth Observation Mission with three satellites flying in a semi-controlled constellation. The trio is operated from ESA's satellite control centre ESOC in Darmstadt, Germany. The Swarm Flight Operations Segment consists of the typical elements of a satellite control system at ESOC, but had to be carefully tailored for this innovative mission. The main challenge was the multi-satellite system of Swarm, which necessitated the development of a Mission Control System with a multi-domain functionality, both in hardware and software and covering real-time and backup domains. This was driven by the need for extreme flexibility for constellation operations and parallel activities.The three months of commissioning in 2014 were characterized by a very tight and dynamically changing schedule of activities. All operational issues could be solved during that time, including the challenging orbit acquisition phase to achieve the final constellation.Although the formal spacecraft commissioning phase was concluded in spring 2014, the investigations for some payload instruments continue even today. The Electrical Field Instruments are for instance still being tested in order to characterize and improve science data quality. Various test phases also became necessary for the Accelerometers on the Swarm satellites. In order to improve the performance of the GPS Receivers for better scientific exploitation and to minimize the failures due to loss of synchronization, a number of parameter changes were commanded via on-board patches.Finally, to minimize the impact on operations, a new strategy had to be implemented to handle single/multi bit errors in the on-board mass Memories, defining when to ignore and when to restore the memory via a re-initialisation.The poster presentation summarizes the Swarm specific ground segment elements of the FOS and explains some of the extended payload commissioning operations, turning Swarm into a most demanding and challenging

Research and implementation of PC data synchronous backup based on cloud computing

OpenAIRE

WU Yu; CHEN Junhua

2013-01-01

In order to better ensure data security，data integrity，and facilitate remote management，this paper has designed and implemented a system model for PC data synchronous backup from the view of the local database and personal data． It focuses on the data backup and uses SQL Azure( a cloud database management system) and Visual Studio( a development platform tool) ． Also the system is released and deployed on the Windows Azure Platform with a unique web portal． Experimental tests show that compar...

Passivity Based Nonlinear Attitude Control of the Rømer Satellite

DEFF Research Database (Denmark)

Quottrup, Michael Melholt; Krogh-Sørensen, J.; Wisniewski, Rafal

2001-01-01

This paper suggests nonlinear attitude control of the Danish satellite Rømer. This satellite will be designed to fulfil two scientific objectives: The observation of stellar oscillations and the detection and localisation of gamma-ray bursts. The satellite will be equipped with a tetrahedron...

How to automatically test and validate your database backup and recovery strategy

International Nuclear Information System (INIS)

Gaspar Aparicio, Ruben

2011-01-01

The major challenge we solve with this software project is the automated validation of backups sent to tape for Oracle databases. While Oracle Recovery Manager (RMAN) provides tools like 'restore validate', the real and only certain proof is a restore. This initial aim evolved to provide a recovery platform capable to cover more complex user cases, such as validations of backup strategy of Very Large DataBases (VLDB), and schema recoveries to cure logical errors or to provide the kind of database snapshots by means of exports.

Analysis design and implementation of a data backup system and restoration of information based on AVAMAR Software

Directory of Open Access Journals (Sweden)

Wilson Chango

2017-12-01

Full Text Available The objective of this research is to make a system for the backup of the information of virtual environments and computers of end users through the LAN network, covering, for this purpose, the analysis, design and implementation at the laboratory level, of a system of specialized backups for these environments in this way was thus checked for its performance and its feasibility of execution, from a technical point of view. AVAMAR, emerges as a solution alternative to face the challenges of those IT environments where backups and retrieval of information demand shorter time windows, more agile recovery responses, end user support and virtual machines. The architecture and technology of this backup and recovery solution makes it ideal for a reference study that shows everything that can be achieved in the complex and varied world of information backup. The scenario that was raised concerns a typical infrastructure consisting of physical, virtual servers, a LAN and a SAN network, users of desktop computers and laptops, end users had connectivity to the servers through the LAN, these computer equipment had Windows as an operating system, a virtual environment was established that was executed on the physical servers, the environment was fully operational and functional, all services were active and users could access them from the LAN network . From this scenario, we analyzed the benefits of the system of backups of the information of end users and virtual machines, optimizing resources such as hardware, software and execution time of backup and recovery tasks

Passivity based nonlinear attitude control of the Rømer satellite

DEFF Research Database (Denmark)

Quottrup, Michael Melholt; Krogh-Sørensen, J.; Wisniewski, Rafal

This paper suggests nonlinear attitude control of the Danish satellite Rømer. This satellite will be designed to fulfil two scientific objectives: The observation of stellar oscillations and the detection and localisation of gamma-ray bursts. The satellite will be equipped with a tetrahedron...... configuration of Wide Angle Telescopes for Cosmic Hard x-rays (WATCH), that server the dual purpose of X-ray detectors and momentum wheels. By employing passivity theory it is shown, that the satellite is a passive system. This paper shows, that global asymptotic can be obtained with a passive and an imput...... and output strictly passive system in a feedback interconnection. It is demonstrated in a simulation study that the resultant control has a potential for on-board implementation in the acquistion phase, where global stabillity of the control law is vital...

Effective Data Backup System Using Storage Area Network Solution

African Journals Online (AJOL)

PROF. OLIVER OSUAGWA

2015-06-01

Jun 1, 2015 ... One of the most crucial benefits of the computer system is its ability to manage data send to it for processing. ... mirroring, backup and restore, archival and retrieval of ..... enable schools and cooperate organization create a ...

Beyond centrality-classifying topological significance using backup efficiency and alternative paths

International Nuclear Information System (INIS)

Shavitt, Yuval; Singer, Yaron

2007-01-01

In complex networks characterized by broad degree distribution, node significance is often associated with its degree or with centrality metrics which relate to its reachability and shortest paths passing through it. Such measures do not consider availability of efficient backup of the node and thus often fail to capture its contribution to the functionality and resilience of the network operation. In this paper, we suggest the quality of backup (QoB) and alternative path centrality (APC) measures as complementary methods which enable analysis of node significance in a manner which considers backup. We examine the theoretical significance of these measures and use them to classify nodes in social interaction networks and in the Internet AS (autonomous system) graph while applying the valley-free routing restrictions which reflect the economic relationships between the AS nodes in the Internet. We show that both node degree and node centrality are not necessarily evidence of its significance. In particular, we show that social structures do not necessarily depend on highly central nodes and that medium degree nodes with medium centrality measure prove to be crucial for efficient routing in the Internet AS graph

Design and analysis of a lightweight prestressed antenna back-up structure

Science.gov (United States)

Ma, Zengxiang; Yang, Dehua; Cheng, Jingquan

2010-07-01

The planned Square Kilometer Array (SKA) includes three thousand 15m antennas. The radio flux density from the sun is stronger, so that a solar array, such as Frequency-Agile Solar Radiotelescope (FASR) with hundreds of dishes can have smaller dish size. Therefore, light weight, low cost dish design is of vital importance. The reflecting surface supported by an antenna back-up structure, generally, should have an RMS surface error less than λ/20 (λ. is the operating wavelength). For resisting gravitational, wind, and ice-snow loadings, an antenna dish also requires reasonable mode frequencies. In this paper, different low cost small or medium back-up structure designs are discussed, including double-layer truss design and prestressed dish design. Based on discussion, an innovative light weight, prestressed back-up structure is proposed for small or medium aperture antennas. Example of a small 4.5m aperture dish design working below 3GHz is presented. This design is a one-layer prestressed truss structure with low weight, ease installation, and low manufacture cost. Structural analysis and modal extraction results show the structure is much stiffer than the same structure without prestressed loading.

An efficient hybrid protection scheme with shared/dedicated backup paths on elastic optical networks

Directory of Open Access Journals (Sweden)

Nogbou G. Anoh

2017-02-01

Full Text Available Fast recovery and minimum utilization of resources are the two main criteria for determining the protection scheme quality. We address the problem of providing a hybrid protection approach on elastic optical networks under contiguity and continuity of available spectrum constraints. Two main hypotheses are used in this paper for backup paths computation. In the first case, it is assumed that backup paths resources are dedicated. In the second case, the assumption is that backup paths resources are available shared resources. The objective of the study is to minimize spectrum utilization to reduce blocking probability on a network. For this purpose, an efficient survivable Hybrid Protection Lightpath (HybPL algorithm is proposed for providing shared or dedicated backup path protection based on the efficient energy calculation and resource availability. Traditional First-Fit and Best-Fit schemes are employed to search and assign the available spectrum resources. The simulation results show that HybPL presents better performance in terms of blocking probability, compared with the Minimum Resources Utilization Dedicated Protection (MRU-DP algorithm which offers better performance than the Dedicated Protection (DP algorithm.

Onsite and Electric Backup Capabilities at Critical Infrastructure Facilities in the United States

Energy Technology Data Exchange (ETDEWEB)

Phillips, Julia A. [Argonne National Lab. (ANL), Argonne, IL (United States); Wallace, Kelly E. [Argonne National Lab. (ANL), Argonne, IL (United States); Kudo, Terence Y. [Argonne National Lab. (ANL), Argonne, IL (United States); Eto, Joseph H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2016-04-01

The following analysis, conducted by Argonne National Laboratory’s (Argonne’s) Risk and Infrastructure Science Center (RISC), details an analysis of electric power backup of national critical infrastructure as captured through the Department of Homeland Security’s (DHS’s) Enhanced Critical Infrastructure Program (ECIP) Initiative. Between January 1, 2011, and September 2014, 3,174 ECIP facility surveys have been conducted. This study focused first on backup capabilities by infrastructure type and then expanded to infrastructure type by census region.

A demand assignment control in international business satellite communications network

Science.gov (United States)

Nohara, Mitsuo; Takeuchi, Yoshio; Takahata, Fumio; Hirata, Yasuo

An experimental system is being developed for use in an international business satellite (IBS) communications network based on demand-assignment (DA) and TDMA techniques. This paper discusses its system design, in particular from the viewpoints of a network configuration, a DA control, and a satellite channel-assignment algorithm. A satellite channel configuration is also presented along with a tradeoff study on transmission rate, HPA output power, satellite resource efficiency, service quality, and so on.

Consensus of satellite cluster flight using an energy-matching optimal control method

Science.gov (United States)

Luo, Jianjun; Zhou, Liang; Zhang, Bo

2017-11-01

This paper presents an optimal control method for consensus of satellite cluster flight under a kind of energy matching condition. Firstly, the relation between energy matching and satellite periodically bounded relative motion is analyzed, and the satellite energy matching principle is applied to configure the initial conditions. Then, period-delayed errors are adopted as state variables to establish the period-delayed errors dynamics models of a single satellite and the cluster. Next a novel satellite cluster feedback control protocol with coupling gain is designed, so that the satellite cluster periodically bounded relative motion consensus problem (period-delayed errors state consensus problem) is transformed to the stability of a set of matrices with the same low dimension. Based on the consensus region theory in the research of multi-agent system consensus issues, the coupling gain can be obtained to satisfy the requirement of consensus region and decouple the satellite cluster information topology and the feedback control gain matrix, which can be determined by Linear quadratic regulator (LQR) optimal method. This method can realize the consensus of satellite cluster period-delayed errors, leading to the consistency of semi-major axes (SMA) and the energy-matching of satellite cluster. Then satellites can emerge the global coordinative cluster behavior. Finally the feasibility and effectiveness of the present energy-matching optimal consensus for satellite cluster flight is verified through numerical simulations.

Introduction of a backup system for data and servers of main IT infrastructure services

International Nuclear Information System (INIS)

Hirayama, Takashi; Kannari, Masaaki

2013-06-01

The optimization of the JAEA network system has been promoted in accordance with the optimization plan which has the fundamental principles of ensuring its dependability, information security and usability. In respect to ensuring the dependability, we addressed to a) the reduction of both trouble probability and recovery time, and b) an execution of the business continuity plan in time of large-scale earthquake. For the latter, we installed an e-mail backup server and an alternate connection to the internet in Kansai Photon Science Institute (Kizu-area) based on lesson learned from the experience of the Great East Japan Earthquake on March 11, 2011. In addition, we introduced a backup system for data and servers of other main IT infrastructure services. This report documents the configuration and operation of the backup system. (author)

DOA estimation for attitude determination on communication satellites

Directory of Open Access Journals (Sweden)

Yang Bin

2014-06-01

Full Text Available In order to determine an appropriate attitude of three-axis stabilized communication satellites, this paper describes a novel attitude determination method using direction of arrival (DOA estimation of a ground signal source. It differs from optical measurement, magnetic field measurement, inertial measurement, and global positioning system (GPS attitude determination. The proposed method is characterized by taking the ground signal source as the attitude reference and acquiring attitude information from DOA estimation. Firstly, an attitude measurement equation with DOA estimation is derived in detail. Then, the error of the measurement equation is analyzed. Finally, an attitude determination algorithm is presented using a dynamic model, the attitude measurement equation, and measurement errors. A developing low Earth orbit (LEO satellite which tests mobile communication technology with smart antennas can be stabilized in three axes by corporately using a magnetometer, reaction wheels, and three-axis magnetorquer rods. Based on the communication satellite, simulation results demonstrate the effectiveness of the method. The method could be a backup of attitude determination to prevent a system failure on the satellite. Its precision depends on the number of snapshots and the input signal-to-noise ratio (SNR with DOA estimation.

DOMe: A deduplication optimization method for the NewSQL database backups.

Directory of Open Access Journals (Sweden)

Longxiang Wang

Full Text Available Reducing duplicated data of database backups is an important application scenario for data deduplication technology. NewSQL is an emerging database system and is now being used more and more widely. NewSQL systems need to improve data reliability by periodically backing up in-memory data, resulting in a lot of duplicated data. The traditional deduplication method is not optimized for the NewSQL server system and cannot take full advantage of hardware resources to optimize deduplication performance. A recent research pointed out that the future NewSQL server will have thousands of CPU cores, large DRAM and huge NVRAM. Therefore, how to utilize these hardware resources to optimize the performance of data deduplication is an important issue. To solve this problem, we propose a deduplication optimization method (DOMe for NewSQL system backup. To take advantage of the large number of CPU cores in the NewSQL server to optimize deduplication performance, DOMe parallelizes the deduplication method based on the fork-join framework. The fingerprint index, which is the key data structure in the deduplication process, is implemented as pure in-memory hash table, which makes full use of the large DRAM in NewSQL system, eliminating the performance bottleneck problem of fingerprint index existing in traditional deduplication method. The H-store is used as a typical NewSQL database system to implement DOMe method. DOMe is experimentally analyzed by two representative backup data. The experimental results show that: 1 DOMe can reduce the duplicated NewSQL backup data. 2 DOMe significantly improves deduplication performance by parallelizing CDC algorithms. In the case of the theoretical speedup ratio of the server is 20.8, the speedup ratio of DOMe can achieve up to 18; 3 DOMe improved the deduplication throughput by 1.5 times through the pure in-memory index optimization method.

High Precision Control of Ship-Mounted Satellite Tracking Antenna

DEFF Research Database (Denmark)

Mohsen, Soltani; Izadi-Zamanabadi, Roozbeh; Wisniewski, Rafal

2007-01-01

The telecommunication on a modern merchandise ship is maintained by means of satellite communication. The task of the tracking system is to position the on-board antenna toward a chosen satellite. The control system is capable of rejecting the external disturbances which affect on the under...

H infinity controller design to a rigid-flexible satellite with two vibration modes

International Nuclear Information System (INIS)

De Souza, A G; De Souza, L C G

2015-01-01

The satellite attitude control system (ACS) design becomes more complex when the satellite structure has components like, flexible solar panels, antennas and mechanical manipulators. These flexible structures can interact with the satellite rigid parts during translational and/or rotational manoeuvre damaging the ACS pointing accuracy. Although, a well-designed controller can suppress such disturbances quickly, the controller error pointing may be limited by the minimum time necessary to suppress such disturbances thus affecting the satellite attitude acquisition. This paper deals with the rigid-flexible satellite ACS design using the H infinity method. The rigid-flexible satellite is represented by a beam connected to a central rigid hub at one end and free at the other one. The equations of motions are obtained considering small flexible deformations and the Euler-Bernoulli hypothesis. The results of the simulations have shown that the H-infinity controller was able to control the rigid motion and suppress the vibrations. (paper)

Attractive manifold-based adaptive solar attitude control of satellites in elliptic orbits

Science.gov (United States)

Lee, Keum W.; Singh, Sahjendra N.

2011-01-01

The paper presents a novel noncertainty-equivalent adaptive (NCEA) control system for the pitch attitude control of satellites in elliptic orbits using solar radiation pressure (SRP). The satellite is equipped with two identical solar flaps to produce control moments. The adaptive law is based on the attractive manifold design using filtered signals for synthesis, which is a modification of the immersion and invariance (I&I) method. The control system has a modular controller-estimator structure and has separate tunable gains. A special feature of this NCEA law is that the trajectories of the satellite converge to a manifold in an extended state space, and the adaptive law recovers the performance of a deterministic controller. This recovery of performance cannot be obtained with certainty-equivalent adaptive (CEA) laws. Simulation results are presented which show that the NCEA law accomplishes precise attitude control of the satellite in an elliptic orbit, despite large parameter uncertainties.

Small Satellite Passive Magnetic Attitude Control

Science.gov (United States)

Gerhardt, David T.

Passive Magnetic Attitude Control (PMAC) is capable of aligning a satellite within 5 degrees of the local magnetic field at low resource cost, making it ideal for a small satellite. However, simulation attempts to date have not been able to predict the attitude dynamics at a level sufficient for mission design. Also, some satellites have suffered from degraded performance due to an incomplete understanding of PMAC system design. This dissertation alleviates these issues by discussing the design, inputs, and validation of PMAC systems for small satellites. Design rules for a PMAC system are defined using the Colorado Student Space Weather Experiment (CSSWE) CubeSat as an example. A Multiplicative Extended Kalman Filter (MEKF) is defined for the attitude determination of a PMAC satellite without a rate gyro. After on-orbit calibration of the off-the-shelf magnetometer and photodiodes and an on-orbit fit to the satellite magnetic moment, the MEKF regularly achieves a three sigma attitude uncertainty of 4 degrees or less. CSSWE is found to settle to the magnetic field in seven days, verifying its attitude design requirement. A Helmholtz cage is constructed and used to characterize the CSSWE bar magnet and hysteresis rods both individually and in the flight configuration. Fitted parameters which govern the magnetic material behavior are used as input to a PMAC dynamics simulation. All components of this simulation are described and defined. Simulation-based dynamics analysis shows that certain initial conditions result in abnormally decreased settling times; these cases may be identified by their dynamic response. The simulation output is compared to the MEKF output; the true dynamics are well modeled and the predicted settling time is found to possess a 20 percent error, a significant improvement over prior simulation.

Backup power working group best practices handbook for maintenance and operation of engine generators, Volume 1. Revision 1

International Nuclear Information System (INIS)

Gross, R.; Padgett, A.B.; Burrows, K.P.; Fairchild, P.N.; Lam, T.; Janes, J.

1997-01-01

This handbook is divided into the four chapters. Chapter one covers the design, procurement, storage, handling and testing of diesel fuel oil to be used in DOE backup power supplies. Chapter two discusses the selection of automatic transfer switches to be used in DOE backup power supplies. Chapter three is about low voltage open frame air circuit breaker operation, testing, and maintenance for DOE backup power supplies. And chapter four covers installation, design, and maintenance of engine cooling water and jacket water systems

Vibration noise control in laser satellite communication

Science.gov (United States)

Saksonov, Avigdor; Shlomi, Arnon; Kopeika, Norman S.

2001-08-01

Laser satellite communication has become especially attractive in recent years. Because the laser beam width is narrow than in the RF or microwave range, the transmitted optical power may be significantly reduced. This leads to development of miniature communication systems with extremely low power consumption. On the other hand, the laser communication channel is very sensitive to vibrations of the optical platform. These vibrations cause angular noise in laser beam pointing, comparable to the laser beam width. As result, as significant portion of the optical power between transmitter and receiver is lost and the bit error rate is increased. Consequently, vibration noise control is a critical problem in laser satellite communication. The direction of the laser beam is corrected with a fast steering mirror (FSM). In this paper are presented two approaches for the FSM control. One is the feedback control that uses an LQG algorithm. The second is the direct feed- forward control when vibration noise is measured by three orthogonal accelerometers and drives directly the F SM. The performances of each approach are evaluated using MATLAB simulations.

Auditory backup alarms: distance-at-first-detection via in-situ experimentation on alarm design and hearing protection effects.

Science.gov (United States)

Alali, Khaled; Casali, John G

2012-01-01

The purpose of this study was to assess normal hearing listeners' performance in detecting a stationary backup alarm signal and to quantify the linear distance at detection point. Detection distances for 12 participants with normal hearing were measured while they were fitted with 7 hearing protectors and while they were unoccluded (open ear). A standard (narrowband) backup alarm signal and a broadband (pulsed white noise) backup alarm signal from Brigade[1] were used. The method of limits, with distance as the physical measurement variable and threshold detection as the task, was employed to find at which distance the participant could first detect the backup alarms. A within-subject Analysis of Variance (ANOVA) revealed a significant main effect of the listening conditions on the detection distance in feet. Post hoc analyses indicated that the Bilsom L3HV conventional passive earmuff (at 1132.2 ft detection distance) was significantly poorer compared to all other HPDs and the open ear in detection distance achieved, and that there were no statistically-significant differences between the unoccluded ear (1652.3 ft), EB-15-Lo BlastPLGTM (1546.2 ft), EB-15-Hi BlastPLGTM (1543.4 ft), E-A-R/3M Combat ArmsTM earplug-nonlinear, level-dependent state (1507.8 ft), E-A-R/3M HiFiTM earplug (1497.7 ft), and Bilsom ImpactTM dichotic electronic earmuff (1567.2 ft). In addition, the E-A-R/3M Combat ArmsTM earplug-passive steady state resulted in significantly longer detection distances than only the open ear condition, at 1474.1 ft versus 1652.3 ft for the open ear. ANOVA also revealed a significant main effect of the backup alarm type on detection distance. The means were 1600.9 ft for the standard (narrowband) backup alarm signal, and a significantly closer 1379.4 ft was required for the Brigade broadband backup alarm signal. For on-ground workers, it is crucial to detect backup alarm signals as far away as possible rather than at close distances since this will provide them

Influence of unbalance levels on nonlinear dynamics of a rotor-backup rolling bearing system

DEFF Research Database (Denmark)

Fonseca, Cesar A.; Santos, Ilmar; Weber, Hans I.

2017-01-01

of nonlinear dynamics applied to the practical use. The theoretical and numerical analyses are shown through orbit plots, phase plans, Poincaré maps, force response in time and double sided spectrum. The latter is important to characterize the condition at different levels of unbalance between forward......Rotor drops in magnetic bearing and unbalance in rotors have been objective of study for many years. The combination of these two well-known phenomena led to an interesting chaotic response, when the rotor touches the inner race of the back-up bearing. The present work explores the nonlinear rotor...... backup bearing dynamics both theoretically and experimentally using a fully instrumented test rig, where the position of shaft, its angular velocity and the contact forces between the shaft and the backup bearing are sampled at 25 kHz. The test rig is built by a removable passive magnetic bearing, which...

Empirical Analysis of High Efficient Remote Cloud Data Center Backup Using HBase and Cassandra

OpenAIRE

Chang, Bao Rong; Tsai, Hsiu-Fen; Chen, Chia-Yen; Guo, Cin-Long

2015-01-01

HBase, a master-slave framework, and Cassandra, a peer-to-peer (P2P) framework, are the two most commonly used large-scale distributed NoSQL databases, especially applicable to the cloud computing with high flexibility and scalability and the ease of big data processing. Regarding storage structure, different structure adopts distinct backup strategy to reduce the risks of data loss. This paper aims to realize high efficient remote cloud data center backup using HBase and Cassandra, and in or...

A Robust Controller Structure for Pico-Satellite Applications

DEFF Research Database (Denmark)

Kragelund, Martin Nygaard; Green, Martin; Kristensen, Mads

This paper describes the development of a robust controller structure for use in pico-satellite missions. The structure relies on unknown disturbance estimation and use of robust control theory to implement a system that is robust to both unmodeled disturbances and parameter uncertainties. As one...

Effective Data Backup System Using Storage Area Network Solution ...

African Journals Online (AJOL)

The primary cause of data loss is lack or non- existent of data backup. Storage Area Network Solution (SANS) is internet-based software which will collect clients data and host them in several locations to forestall data loss in case of disaster in one location. The researcher used adobe Dreamweaver (CSC3) embedded with ...

30 CFR 75.1101-21 - Back-up water system.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Back-up water system. 75.1101-21 Section 75.1101-21 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY... water system. One fire hose outlet together with a length of hose capable of extending to the belt drive...

Effect of Remote Back-Up Protection System Failure on the Optimum Routine Test Time Interval of Power System Protection

Directory of Open Access Journals (Sweden)

Y Damchi

2013-12-01

Full Text Available Appropriate operation of protection system is one of the effective factors to have a desirable reliability in power systems, which vitally needs routine test of protection system. Precise determination of optimum routine test time interval (ORTTI plays a vital role in predicting the maintenance costs of protection system. In the most previous studies, ORTTI has been determined while remote back-up protection system was considered fully reliable. This assumption is not exactly correct since remote back-up protection system may operate incorrectly or fail to operate, the same as the primary protection system. Therefore, in order to determine the ORTTI, an extended Markov model is proposed in this paper considering failure probability for remote back-up protection system. In the proposed Markov model of the protection systems, monitoring facility is taken into account. Moreover, it is assumed that the primary and back-up protection systems are maintained simultaneously. Results show that the effect of remote back-up protection system failures on the reliability indices and optimum routine test intervals of protection system is considerable.

Simulating cloud environment for HIS backup using secret sharing.

Science.gov (United States)

Kuroda, Tomohiro; Kimura, Eizen; Matsumura, Yasushi; Yamashita, Yoshinori; Hiramatsu, Haruhiko; Kume, Naoto

2013-01-01

In the face of a disaster hospitals are expected to be able to continue providing efficient and high-quality care to patients. It is therefore crucial for hospitals to develop business continuity plans (BCPs) that identify their vulnerabilities, and prepare procedures to overcome them. A key aspect of most hospitals' BCPs is creating the backup of the hospital information system (HIS) data at multiple remote sites. However, the need to keep the data confidential dramatically increases the costs of making such backups. Secret sharing is a method to split an original secret message so that individual pieces are meaningless, but putting sufficient number of pieces together reveals the original message. It allows creation of pseudo-redundant arrays of independent disks for privacy-sensitive data over the Internet. We developed a secret sharing environment for StarBED, a large-scale network experiment environment, and evaluated its potential and performance during disaster recovery. Simulation results showed that the entire main HIS database of Kyoto University Hospital could be retrieved within three days even if one of the distributed storage systems crashed during a disaster.

Planning of Vehicle Routing with Backup Provisioning Using Wireless Sensor Technologies

Directory of Open Access Journals (Sweden)

Noélia Correia

2017-08-01

Full Text Available Wireless sensor technologies can be used by intelligent transportation systems to provide innovative services that lead to improvements in road safety and congestion, increasing end-user satisfaction. In this article, we address vehicle routing with backup provisioning, where the possibility of reacting to overloading/overcrowding of vehicles at certain stops is considered. This is based on the availability of vehicle load information, which can be captured using wireless sensor technologies. After discussing the infrastructure and monitoring tool, the problem is mathematically formalized, and a heuristic algorithm using local search procedures is proposed. Results show that planning routes with backup provisioning can allow fast response to overcrowding while reducing costs. Therefore, sustainable urban mobility, with efficient use of resources, can be provided while increasing the quality of service perceived by users.

Attitude Control of a Satellite by using Digital Signal Processing

Directory of Open Access Journals (Sweden)

Adirelle C. Santana

2012-03-01

Full Text Available This article has discussed the development of a three-axis attitude digital controller for an artificial satellite using a digital signal processor. The main motivation of this study is the attitude control system of the satellite Multi-Mission Platform, developed by the Brazilian National Institute for Space Research for application in different sort of missions. The controller design was based on the theory of the Linear Quadratic Gaussian Regulator, synthesized from the linearized model of the motion of the satellite, i.e., the kinematics and dynamics of attitude. The attitude actuators considered in this study are pairs of cold gas jets powered by a pulse width/pulse frequency modulator. In the first stage of the project development, a system controller for continuous time was studied with the aim of testing the adequacy of the adopted control. The next steps had included an analysis of discretization techniques, the setting time of sampling rate, and the testing of the digital version of the Linear Quadratic Gaussian Regulator controller in the MATLAB/SIMULINK. To fulfill the study, the controller was implemented in a digital signal processor, specifically the Blackfin BF537 from Analog Devices, along with the pulse width/pulse frequency modulator. The validation tests used a scheme of co-simulation, where the model of the satellite was simulated in MATLAB/SIMULINK, while the controller and modulator were processed in the digital signal processor with a tool called Processor-In-the-Loop, which acted as a data communication link between both environments.function and required time to achieve a given mission accuracy are determined, and results are provided as illustration.

Partially Decentralized Control Architectures for Satellite Formations

Science.gov (United States)

Carpenter, J. Russell; Bauer, Frank H.

2002-01-01

In a partially decentralized control architecture, more than one but less than all nodes have supervisory capability. This paper describes an approach to choosing the number of supervisors in such au architecture, based on a reliability vs. cost trade. It also considers the implications of these results for the design of navigation systems for satellite formations that could be controlled with a partially decentralized architecture. Using an assumed cost model, analytic and simulation-based results indicate that it may be cheaper to achieve a given overall system reliability with a partially decentralized architecture containing only a few supervisors, than with either fully decentralized or purely centralized architectures. Nominally, the subset of supervisors may act as centralized estimation and control nodes for corresponding subsets of the remaining subordinate nodes, and act as decentralized estimation and control peers with respect to each other. However, in the context of partially decentralized satellite formation control, the absolute positions and velocities of each spacecraft are unique, so that correlations which make estimates using only local information suboptimal only occur through common biases and process noise. Covariance and monte-carlo analysis of a simplified system show that this lack of correlation may allow simplification of the local estimators while preserving the global optimality of the maneuvers commanded by the supervisors.

ObliviSync: Practical Oblivious File Backup and Synchronization

OpenAIRE

Aviv, Adam J.; Choi, Seung Geol; Mayberry, Travis; Roche, Daniel S.

2016-01-01

Oblivious RAM (ORAM) protocols are powerful techniques that hide a client's data as well as access patterns from untrusted service providers. We present an oblivious cloud storage system, ObliviSync, that specifically targets one of the most widely-used personal cloud storage paradigms: synchronization and backup services, popular examples of which are Dropbox, iCloud Drive, and Google Drive. This setting provides a unique opportunity because the above privacy properties can be achieved with ...

Evaluation of microstructure and mechanical properties of 50Cr5NiMoV steel for forged backup roll

Energy Technology Data Exchange (ETDEWEB)

Song, X.Y.; Zhang, X.J.; Fu, L.C.; Yang, H.B.; Yang, K.; Zhu, L., E-mail: zl508@126.com

2016-11-20

The microstructure and mechanical properties of forged 50Cr5NiMoV steel backup roll were evaluated in this study. The microstructure characteristics from surface to center along radial direction of the backup roll were carefully observed by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the chemical composition, hardness, tensile property, impact and fracture toughness in different position of the backup roll were also examined. The results indicate that the finely precipitated carbides at different matrix during heat treatment process strongly influence mechanical properties of the backup roll. Especially, the spheroidized pearlite at the inner regions which consists of large globular or rod-like M{sub 7}C{sub 3} and a little of small globular M{sub 23}C{sub 6} possesses much better toughness and fracture resistance properties than those of the lamellar pearlite with lamellar M{sub 23}C{sub 6} and a little of globular M{sub 7}C{sub 3}.

Visibility of children behind 2010-2013 model year passenger vehicles using glances, mirrors, and backup cameras and parking sensors.

Science.gov (United States)

Kidd, David G; Brethwaite, Andrew

2014-05-01

This study identified the areas behind vehicles where younger and older children are not visible and measured the extent to which vehicle technologies improve visibility. Rear visibility of targets simulating the heights of a 12-15-month-old, a 30-36-month-old, and a 60-72-month-old child was assessed in 21 2010-2013 model year passenger vehicles with a backup camera or a backup camera plus parking sensor system. The average blind zone for a 12-15-month-old was twice as large as it was for a 60-72-month-old. Large SUVs had the worst rear visibility and small cars had the best. Increases in rear visibility provided by backup cameras were larger than the non-visible areas detected by parking sensors, but parking sensors detected objects in areas near the rear of the vehicle that were not visible in the camera or other fields of view. Overall, backup cameras and backup cameras plus parking sensors reduced the blind zone by around 90 percent on average and have the potential to prevent backover crashes if drivers use the technology appropriately. Copyright © 2014 Elsevier Ltd. All rights reserved.

Life cycle assessment of greenhouse gas emissions, water and land use for concentrated solar power plants with different energy backup systems

International Nuclear Information System (INIS)

Klein, Sharon J.W.; Rubin, Edward S.

2013-01-01

Concentrated solar power (CSP) is unique among intermittent renewable energy options because for the past four years, utility-scale plants have been using an energy storage technology that could allow a CSP plant to operate as a baseload renewable energy generator in the future. No study to-date has directly compared the environmental implications of this technology with more conventional CSP backup energy options. This study compares the life cycle greenhouse gas (GHG) emissions, water consumption, and direct, onsite land use associated with one MW h of electricity production from CSP plants with wet and dry cooling and with three energy backup systems: (1) minimal backup (MB), (2) molten salt thermal energy storage (TES), and (3) a natural gas-fired heat transfer fluid heater (NG). Plants with NG had 4–9 times more life cycle GHG emissions than plants with TES. Plants with TES generally had twice as many life cycle GHG emissions as the MB plants. Dry cooling reduced life cycle water consumption by 71–78% compared to wet cooling. Plants with larger backup capacities had greater life cycle water consumption than plants with smaller backup capacities, and plants with NG had lower direct, onsite life cycle land use than plants with MB or TES. - highlights: • We assess life cycle environmental effects of concentrated solar power (CSP). • We compare CSP with three energy backup technologies and two cooling technologies. • We selected solar field area to minimize energy cost for plants with minimal backup and salt storage. • Life cycle greenhouse gas emissions were 4–9 times lower with thermal energy storage than with fossil fuel backup. • Dry cooling reduced life cycle water use by 71–78% compared to wet cooling

Report of study group 3.3 ''LNG and LPG peak shaving and satellite plants''; Rapport du groupe d'etude 3.3 ''usines d'ecretement de pointes et stations satellites GNL et GPL''

Energy Technology Data Exchange (ETDEWEB)

Klein Nagelvoort, R.

2000-07-01

This report presents a world-wide overview of LNG and LPG Peak Shaving and Satellite Plants, compiled by the study group 3.3 of the International Gas Union. The scope of the work of the study group includes: - LPG peak shavers (LPG + air, N{sub 2}) in gas distribution networks; - LPG peak shavers for start-up and back-up fuel for LNG terminals and power stations; - LNG peak shavers for gas distribution networks; - Small-scale liquefaction plants for distribution to satellites and dedicated consumers (e.g. power generators, chemical plants, trucking companies etc.); - LNG peak shavers as back-up for large consumers; - Alternative liquefaction technologies for LNG and LPG (e.g. refrigeration cycles, supersonic expansion, thermo-acoustic designs); - Alternative storage tank designs for LNG and LPG. The report presents an overview of current installations world-wide and considers the prospects of technological developments with respect to equipment, remote operations and safety constraints. It also includes where possible a review of capital and operating costs, regulations, and an identification of opportunities and trends. The report collates the information available to the study group at the time of the writing, which may explain some heterogeneity in the document. (author)

Optimal electricity dispatch on isolated mini-grids using a demand response strategy for thermal storage backup with genetic algorithms

International Nuclear Information System (INIS)

Neves, Diana; Silva, Carlos A.

2015-01-01

The present study uses the DHW (domestic hot water) electric backup from solar thermal systems to optimize the total electricity dispatch of an isolated mini-grid. The proposed approach estimates the hourly DHW load, and proposes and simulates different DR (demand response) strategies, from the supply side, to minimize the dispatch costs of an energy system. The case study consists on optimizing the electricity load, in a representative day with low solar radiation, in Corvo Island, Azores. The DHW backup is induced by three different demand patterns. The study compares different DR strategies: backup at demand (no strategy), pre-scheduled backup using two different imposed schedules, a strategy based on linear programming, and finally two strategies using genetic algorithms, with different formulations for DHW backup – one that assigns number of systems and another that assigns energy demand. It is concluded that pre-determined DR strategies may increase the generation costs, but DR strategies based on optimization algorithms are able to decrease generation costs. In particular, linear programming is the strategy that presents the lowest increase on dispatch costs, but the strategy based on genetic algorithms is the one that best minimizes both daily operation costs and total energy demand, of the system. - Highlights: • Integrated hourly model of DHW electric impact and electricity dispatch of isolated grid. • Proposal and comparison of different DR (demand response) strategies for DHW backup. • LP strategy presents 12% increase on total electric load, plus 5% on dispatch costs. • GA strategy presents 7% increase on total electric load, plus 8% on dispatch costs

Integration of multiple, excess, backup, and expected covering models

OpenAIRE

M S Daskin; K Hogan; C ReVelle

1988-01-01

The concepts of multiple, excess, backup, and expected coverage are defined. Model formulations using these constructs are reviewed and contrasted to illustrate the relationships between them. Several new formulations are presented as is a new derivation of the expected covering model which indicates more clearly the relationship of the model to other multi-state covering models. An expected covering model with multiple time standards is also presented.

Guidance, Navigation, and Control Techniques and Technologies for Active Satellite Removal

Science.gov (United States)

Ortega Hernando, Guillermo; Erb, Sven; Cropp, Alexander; Voirin, Thomas; Dubois-Matra, Olivier; Rinalducci, Antonio; Visentin, Gianfranco; Innocenti, Luisa; Raposo, Ana

2013-09-01

This paper shows an internal feasibility analysis to de- orbit a non-functional satellite of big dimensions by the Technical Directorate of the European Space Agency ESA. The paper focuses specifically on the design of the techniques and technologies for the Guidance, Navigation, and Control (GNC) system of the spacecraft mission that will capture the satellite and ultimately will de-orbit it on a controlled re-entry.The paper explains the guidance strategies to launch, rendezvous, close-approach, and capture the target satellite. The guidance strategy uses chaser manoeuvres, hold points, and collision avoidance trajectories to ensure a safe capture. It also details the guidance profile to de-orbit it in a controlled re-entry.The paper continues with an analysis of the required sensing suite and the navigation algorithms to allow the homing, fly-around, and capture of the target satellite. The emphasis is placed around the design of a system to allow the rendezvous with an un-cooperative target, including the autonomous acquisition of both the orbital elements and the attitude of the target satellite.Analysing the capture phase, the paper provides a trade- off between two selected capture systems: the net and the tentacles. Both are studied from the point of view of the GNC system.The paper analyses as well the advanced algorithms proposed to control the final compound after the capture that will allow the controlled de-orbiting of the assembly in a safe place in the Earth.The paper ends proposing the continuation of this work with the extension to the analysis of the destruction process of the compound in consecutive segments starting from the entry gate to the rupture and break up.

Effectiveness of Backup and Disaster Recovery in Cloud : A Comparative study on Disk and Cloud based Backup and Disaster Recovery

OpenAIRE

Kaveti, Akash

2015-01-01

Context: Definitive information is what makes enterprises in the contemporary world continuously move up the ladder in today’s world. Hence they need to be always up to date with the latest advancements. A key point in the enterprise structure is Backup and Disaster Recovery, DR system and this has very high scope for development since it can be integrated with a lot of our daily requirements. On account of this, it has a lot of applicability in future for development of technology. Due to th...

Simplified Analytic Approach of Pole-to-Pole Faults in MMC-HVDC for AC System Backup Protection Setting Calculation

Directory of Open Access Journals (Sweden)

Tongkun Lan

2018-01-01

Full Text Available AC (alternating current system backup protection setting calculation is an important basis for ensuring the safe operation of power grids. With the increasing integration of modular multilevel converter based high voltage direct current (MMC-HVDC into power grids, it has been a big challenge for the AC system backup protection setting calculation, as the MMC-HVDC lacks the fault self-clearance capability under pole-to-pole faults. This paper focused on the pole-to-pole faults analysis for the AC system backup protection setting calculation. The principles of pole-to-pole faults analysis were discussed first according to the standard of the AC system protection setting calculation. Then, the influence of fault resistance on the fault process was investigated. A simplified analytic approach of pole-to-pole faults in MMC-HVDC for the AC system backup protection setting calculation was proposed. In the proposed approach, the derived expressions of fundamental frequency current are applicable under arbitrary fault resistance. The accuracy of the proposed approach was demonstrated by PSCAD/EMTDC (Power Systems Computer-Aided Design/Electromagnetic Transients including DC simulations.

STS-9 payload specialist Merbold and backup Ockels in training session

Science.gov (United States)

1983-01-01

STS-9 payload specialist Ulf Merbold, right, a West German physicist and backup Wubbo Ockels, a Dutch scientist, are pictured in a training session in JSC's Shuttle mockup and integration laboratory. In this view Ockels appears to be showing Merbold how to operate a camera.

The amino acid's backup bone - storage solutions for proteomics facilities.

Science.gov (United States)

Meckel, Hagen; Stephan, Christian; Bunse, Christian; Krafzik, Michael; Reher, Christopher; Kohl, Michael; Meyer, Helmut Erich; Eisenacher, Martin

2014-01-01

Proteomics methods, especially high-throughput mass spectrometry analysis have been continually developed and improved over the years. The analysis of complex biological samples produces large volumes of raw data. Data storage and recovery management pose substantial challenges to biomedical or proteomic facilities regarding backup and archiving concepts as well as hardware requirements. In this article we describe differences between the terms backup and archive with regard to manual and automatic approaches. We also introduce different storage concepts and technologies from transportable media to professional solutions such as redundant array of independent disks (RAID) systems, network attached storages (NAS) and storage area network (SAN). Moreover, we present a software solution, which we developed for the purpose of long-term preservation of large mass spectrometry raw data files on an object storage device (OSD) archiving system. Finally, advantages, disadvantages, and experiences from routine operations of the presented concepts and technologies are evaluated and discussed. This article is part of a Special Issue entitled: Computational Proteomics in the Post-Identification Era. Guest Editors: Martin Eisenacher and Christian Stephan. Copyright © 2013. Published by Elsevier B.V.

Real time hardware-in-loop simulation of ESMO satellite attitude control system

Directory of Open Access Journals (Sweden)

Rune Finnset

2006-04-01

Full Text Available This paper studies attitude control of the ESMO satellite using six reaction thrusters. Bang-bang control with dead-zone and Pulse-Width Modulation (PWM for the modulation of the on-time of the thrusters are treated. Closed loop hardware-in-loop simulations, using themicrocontroller unit (MCU Microchip PIC18F452 for implementation of attitude control and MatLab in a standard PC for simulating satellite dynamics, are carried out. Results for real time simulation are compared with autonomous simulations. The controller gives a satisfactory performance in the real time environment.

Multicast backup reprovisioning problem for Hamiltonian cycle-based protection on WDM networks

Science.gov (United States)

Din, Der-Rong; Huang, Jen-Shen

2014-03-01

As networks grow in size and complexity, the chance and the impact of failures increase dramatically. The pre-allocated backup resources cannot provide 100% protection guarantee when continuous failures occur in a network. In this paper, the multicast backup re-provisioning problem (MBRP) for Hamiltonian cycle (HC)-based protection on WDM networks for the link-failure case is studied. We focus on how to recover the protecting capabilities of Hamiltonian cycle against the subsequent link-failures on WDM networks for multicast transmissions, after recovering the multicast trees affected by the previous link-failure. Since this problem is a hard problem, an algorithm, which consists of several heuristics and a genetic algorithm (GA), is proposed to solve it. The simulation results of the proposed method are also given. Experimental results indicate that the proposed algorithm can solve this problem efficiently.

Tilted wheel satellite attitude control with air-bearing table experimental results

Science.gov (United States)

Inumoh, Lawrence O.; Forshaw, Jason L.; Horri, Nadjim M.

2015-12-01

Gyroscopic actuators for satellite control have attracted significant research interest over the years, but their viability for the control of small satellites has only recently started to become clear. Research on variable speed gyroscopic actuators has long been focused on single gimbal actuators; double gimbal actuators typically operate at constant wheel spin rate and allow tilt angle ranges far larger than the ranges needed to operate most satellite missions. This research examines a tilted wheel, a newly proposed type of inertial actuator that can generate torques in all three principal axes of a rigid satellite using a spinning wheel and a double tilt mechanism. The tilt mechanism tilts the angular momentum vector about two axes providing two degree of freedom control, while variation of the wheel speed provides the third. The equations of motion of the system lead to a singularity-free system during nominal operation avoiding the need for complex steering logic. This paper describes the hardware design of the tilted wheel and the experimental setup behind both standalone and spherical air-bearing tables used to test it. Experimental results from the air bearing table are provided with the results depicting the high performance capabilities of the proposed actuator in torque generation.

A Survey of Congestion Control Techniques and Data Link Protocols in Satellite Networks

OpenAIRE

Fahmy, Sonia; Jain, Raj; Lu, Fang; Kalyanaraman, Shivkumar

1998-01-01

Satellite communication systems are the means of realizing a global broadband integrated services digital network. Due to the statistical nature of the integrated services traffic, the resulting rate fluctuations and burstiness render congestion control a complicated, yet indispensable function. The long propagation delay of the earth-satellite link further imposes severe demands and constraints on the congestion control schemes, as well as the media access control techniques and retransmissi...

Heuristic methods for shared backup path protection planning

DEFF Research Database (Denmark)

Haahr, Jørgen Thorlund; Stidsen, Thomas Riis; Zachariasen, Martin

2012-01-01

schemes are employed. In contrast to manual intervention, automatic protection schemes such as Shared Backup Path Protection (SBPP) can recover from failure quickly and efficiently. SBPP is a simple but efficient protection scheme that can be implemented in backbone networks with technology available...... present heuristic algorithms and lower bound methods for the SBPP planning problem. Experimental results show that the heuristic algorithms are able to find good quality solutions in minutes. A solution gap of less than 3.5% was achieved for more than half of the benchmark instances (and a gap of less...

A right hemisphere safety backup at work: hypotheses for deep hypnosis, post-traumatic stress disorder, and dissociation identity disorder.

Science.gov (United States)

Burnand, Gordon

2013-09-01

Problem theory points to an a priori relation between six key problems of living, to which people have adapted through evolution. Children are guided through the problems one by one, learning to switch between them automatically and unawares. The first problem of raising hope of certainty (about the environment), is dealt with in the right hemisphere (RH). The second of raising hope of freedom (or power to control), is dealt with in the left hemisphere (LH). Here adventurousness and ignoring the goodness of outcomes potentially create recklessness. When uncertainty rises the RH activates a backup with an override that substitutes immobility, takes over sensory inputs, but allows obedience to parental commands, and a cut-out that stops new work on the freedom problem. Support for the use of the backup by infants is found in the immobility that precedes the crying in strange conditions, and in childhood EEGs. The hypothesis that the backup is active in deep hypnosis imposes accord on findings that appear contradictory. For example it accounts for why observations during deep hypnosis emphasize the activity of the RH, but observations of responsive people not under hypnosis emphasize the activity of the LH. The hypothesis that the backup is active in post-traumatic stress disorder (PTSD) is supported by (a) fMRI observations that could reflect the cut-out, in that part of the precuneus has low metabolism, (b) the recall of motionlessness at the time of the trauma, (c) an argument that playing dead as a defence against predators is illogical, (d) the ease of hypnosis. With dissociative identity disorder (DID), the theory is consistent with up to six alters that have executive control and one trauma identity state where childhood traumas are re-experienced. Support for the cut-out affecting the trauma identity state comes from suppression of part of the precuneus and other parts of the parietal lobe when the trauma identity state is salient and a general script about a

Attitude Control Subsystem for the Advanced Communications Technology Satellite

Science.gov (United States)

Hewston, Alan W.; Mitchell, Kent A.; Sawicki, Jerzy T.

1996-01-01

This paper provides an overview of the on-orbit operation of the Attitude Control Subsystem (ACS) for the Advanced Communications Technology Satellite (ACTS). The three ACTS control axes are defined, including the means for sensing attitude and determining the pointing errors. The desired pointing requirements for various modes of control as well as the disturbance torques that oppose the control are identified. Finally, the hardware actuators and control loops utilized to reduce the attitude error are described.

Accelerating Acceptance of Fuel Cell Backup Power Systems - Final Report

Energy Technology Data Exchange (ETDEWEB)

Petrecky, James; Ashley, Christopher

2014-07-21

Since 2001, Plug Power has installed more than 800 stationary fuel cell systems worldwide. Plug Power’s prime power systems have produced approximately 6.5 million kilowatt hours of electricity and have accumulated more than 2.5 million operating hours. Intermittent, or backup, power products have been deployed with telecommunications carriers and government and utility customers in North and South America, Europe, the United Kingdom, Japan and South Africa. Some of the largest material handling operations in North America are currently using the company’s motive power units in fuel cell-powered forklifts for their warehouses, distribution centers and manufacturing facilities. The low-temperature GenSys fuel cell system provides remote, off-grid and primary power where grid power is unreliable or nonexistent. Built reliable and designed rugged, low- temperature GenSys delivers continuous or backup power through even the most extreme conditions. Coupled with high-efficiency ratings, low-temperature GenSys reduces operating costs making it an economical solution for prime power requirements. Currently, field trials at telecommunication and industrial sites across the globe are proving the advantages of fuel cells—lower maintenance, fuel costs and emissions, as well as longer life—compared with traditional internal combustion engines.

Reliable Control of Ship-mounted Satellite Tracking Antenna

DEFF Research Database (Denmark)

Soltani, Mohsen; Izadi-Zamanabadi, Roozbeh; Wisniewski, Rafal

2010-01-01

Motorized antenna is a key element in overseas satellite telecommunication. The control system directs the on-board antenna toward a chosen satellitewhile the high sea waves disturb the antenna. Certain faults (communication system malfunction or signal blocking) cause interruption in the communi...

CanDan 2, phase 2. Final report. [Fuel cell systems for back-up power and materials handling applications]; CanDan 2, fase 2. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-11-01

CanDan 2 Phase 2 is the second phase of a research and demonstration project for fuel cell backup power systems and fuel cell powered material handling equipment. In the Backup Power segment the fuel cell units have been developed, certified and delivered. A total of 32 fuel cell backup power systems have been delivered for EnergiMidt and in operation since early 2011. Following this project EnergiMidt has purchased another 31 systems in order to make a full transition from battery backup to fuel cell backup in their entire broadband network. In the material handling segment a 10 kW fuel cell system has been fully integrated in the fork lift truck, Dantruck 3000 Power Hydrogen. The result was a much more commercially mature product than expected from the beginning of the project. The result is a finished 2,5T fork lift truck which was presented at the CE-mat fair in April 2011. (LN)

New flexible thermal control material for long-life satellite

International Nuclear Information System (INIS)

Sasaki, Shigekuni; Hasuda, Yoshinori; Ichino, Toshihiro

1986-01-01

Flexible thermal control materials are light weight, cheap and excellent in the practical applicability, and are expected to be applied to future long life, large capacity satellites. However, the flexible thermal control materials used at present have the defect that either the space environment withstanding capability or the thermal control performance is poor. Therefore, the authors examined the flexible thermal control materials which are excellent in both these properties, and have developed the thermal control material PEI-OSR using polyether imide films as the substrate. In this study, while comparing with the FEP Teflon with silver vapor deposition, which has been used so far for short life satellites, the long term reliability of the PEI-OSR supposing the use for seven years was examined. As the results, the FEP Teflon with silver vapor deposition caused cracking and separation by irradiation and heat cycle test, and became unusable, but the PEI-OSR did not change its flexibility at all. Also the thermal control performance of the PEI-OSR after the test equivalent to seven years was superior to the initial performance of the Kaptone with aluminum vapor deposition, which has excellent space environment endurance, thus it was clarified that the PEI-OSR is the most excellent for this purpose. (Kako, I.)

Feasibility analysis of a hydrogen backup power system for Russian telecom market

Science.gov (United States)

Borzenko, V. I.; Dunikov, D. O.

2017-11-01

We performed feasibility analysis of 10 kW hydrogen backup power system (H2BS) consisting of a water electrolyzer, a metal hydride hydrogen storage and a fuel cell. Capital investments in H2BS are mostly determined by the costs of the PEM electrolyzer, the fuel cell and solid state hydrogen storage materials, for single unit or small series manufacture the cost of AB5-type intermetallic compound can reach 50% of total system cost. Today the capital investments in H2BS are 3 times higher than in conventional lead-acid system of the same capacity. Wide distribution of fuel cell hydrogen vehicles, development of hydrogen infrastructure, and mass production of hydrogen power systems will for sure lower capital investments in fuel cell backup power. Operational expenditures for H2BS is only 15% from the expenditures for lead acid systems, and after 4-5 years of exploitation the total cost of ownership will become lower than for batteries.

Integrated identification and control for nanosatellites reclaiming failed satellite

Science.gov (United States)

Han, Nan; Luo, Jianjun; Ma, Weihua; Yuan, Jianping

2018-05-01

Using nanosatellites to reclaim a failed satellite needs nanosatellites to attach to its surface to take over its attitude control function. This is challenging, since parameters including the inertia matrix of the combined spacecraft and the relative attitude information of attached nanosatellites with respect to the given body-fixed frame of the failed satellite are all unknown after the attachment. Besides, if the total control capacity needs to be increased during the reclaiming process by new nanosatellites, real-time parameters updating will be necessary. For these reasons, an integrated identification and control method is proposed in this paper, which enables the real-time parameters identification and attitude takeover control to be conducted concurrently. Identification of the inertia matrix of the combined spacecraft and the relative attitude information of attached nanosatellites are both considered. To guarantee sufficient excitation for the identification of the inertia matrix, a modified identification equation is established by filtering out sample points leading to ill-conditioned identification, and the identification performance of the inertia matrix is improved. Based on the real-time estimated inertia matrix, an attitude takeover controller is designed, the stability of the controller is analysed using Lyapunov method. The commanded control torques are allocated to each nanosatellite while the control saturation constraint being satisfied using the Quadratic Programming (QP) method. Numerical simulations are carried out to demonstrate the feasibility and effectiveness of the proposed integrated identification and control method.

Neural networks based three-axis satellite attitude control using only magnetic torquers

International Nuclear Information System (INIS)

Sivaprakash, N.; Shanmugam, J.; Natarajan, P.

2005-01-01

Full text: Magnetic control is a favorable way to stabilize small satellites. Often, the hardware is simple and lightweight, and does not degrade or change mass over time. However, a magnetic control system does have some disadvantages and limitations. The control, which is in the form of magnetic moment, can only be applied perpendicular to the local magnetic field. In addition, there is uncertainty in the Earth magnetic field models due to the complicated dynamic nature of the field. Also, the magnetic hardware and the spacecraft can interact, causing both to behave in undesirable ways. To overcome these limitations some intelligence is incorporated in the controller. In this paper, control laws are developed to stabilize spacecraft on Three axes. The motivation for this project is ANUSAT, which is a micro-satellite under development at Anna University in collaboration with ISRO. This control could be carried out solely with satellite's magnetometer measurements and its position in orbit. The magnetic dipole moment for control is: M = K p (B o - B r ) + K d (dB o /dt - dB r /dt) Where B o is the measured magnetic field, B r is the reference magnetic field, and K p and K d are the control position and rate gains respectively. The value of the controller gains are selected by the Intelligent Neural Network System in the feedback path. Control laws are numerically tested to show that the magnetic control system works within resolution limits

Optimization of robustness of interdependent network controllability by redundant design.

Directory of Open Access Journals (Sweden)

Zenghu Zhang

Full Text Available Controllability of complex networks has been a hot topic in recent years. Real networks regarded as interdependent networks are always coupled together by multiple networks. The cascading process of interdependent networks including interdependent failure and overload failure will destroy the robustness of controllability for the whole network. Therefore, the optimization of the robustness of interdependent network controllability is of great importance in the research area of complex networks. In this paper, based on the model of interdependent networks constructed first, we determine the cascading process under different proportions of node attacks. Then, the structural controllability of interdependent networks is measured by the minimum driver nodes. Furthermore, we propose a parameter which can be obtained by the structure and minimum driver set of interdependent networks under different proportions of node attacks and analyze the robustness for interdependent network controllability. Finally, we optimize the robustness of interdependent network controllability by redundant design including node backup and redundancy edge backup and improve the redundant design by proposing different strategies according to their cost. Comparative strategies of redundant design are conducted to find the best strategy. Results shows that node backup and redundancy edge backup can indeed decrease those nodes suffering from failure and improve the robustness of controllability. Considering the cost of redundant design, we should choose BBS (betweenness-based strategy or DBS (degree based strategy for node backup and HDF(high degree first for redundancy edge backup. Above all, our proposed strategies are feasible and effective at improving the robustness of interdependent network controllability.

A Piecewise Affine Hybrid Systems Approach to Fault Tolerant Satellite Formation Control

DEFF Research Database (Denmark)

Grunnet, Jacob Deleuran; Larsen, Jesper Abildgaard; Bak, Thomas

2008-01-01

In this paper a procedure for modelling satellite formations   including failure dynamics as a piecewise-affine hybrid system is   shown. The formulation enables recently developed methods and tools   for control and analysis of piecewise-affine systems to be applied   leading to synthesis of fault...... tolerant controllers and analysis of   the system behaviour given possible faults.  The method is   illustrated using a simple example involving two satellites trying   to reach a specific formation despite of actuator faults occurring....

Utilizing data grid architecture for the backup and recovery of clinical image data.

Science.gov (United States)

Liu, Brent J; Zhou, M Z; Documet, J

2005-01-01

Grid Computing represents the latest and most exciting technology to evolve from the familiar realm of parallel, peer-to-peer and client-server models. However, there has been limited investigation into the impact of this emerging technology in medical imaging and informatics. In particular, PACS technology, an established clinical image repository system, while having matured significantly during the past ten years, still remains weak in the area of clinical image data backup. Current solutions are expensive or time consuming and the technology is far from foolproof. Many large-scale PACS archive systems still encounter downtime for hours or days, which has the critical effect of crippling daily clinical operations. In this paper, a review of current backup solutions will be presented along with a brief introduction to grid technology. Finally, research and development utilizing the grid architecture for the recovery of clinical image data, in particular, PACS image data, will be presented. The focus of this paper is centered on applying a grid computing architecture to a DICOM environment since DICOM has become the standard for clinical image data and PACS utilizes this standard. A federation of PACS can be created allowing a failed PACS archive to recover its image data from others in the federation in a seamless fashion. The design reflects the five-layer architecture of grid computing: Fabric, Resource, Connectivity, Collective, and Application Layers. The testbed Data Grid is composed of one research laboratory and two clinical sites. The Globus 3.0 Toolkit (Co-developed by the Argonne National Laboratory and Information Sciences Institute, USC) for developing the core and user level middleware is utilized to achieve grid connectivity. The successful implementation and evaluation of utilizing data grid architecture for clinical PACS data backup and recovery will provide an understanding of the methodology for using Data Grid in clinical image data backup for

Zinc Bromide Flow Battery Installation for Islanding and Backup Power

Science.gov (United States)

2017-08-09

demonstrates the energy security and cost benefits of implementing a Zn/Br Flow Battery-based ESS at the Marine Corps Air Station (MCAS) located at...user will be realized through the system’s peak shaving mode. This benefit was also used to calculate the operational cost reductions when using the...EW-201242) Zinc Bromide Flow Battery Installation for Islanding and Backup Power August 2017 This document has been cleared for public release

Bayes-Based Fault Discrimination in Wide Area Backup Protection

Directory of Open Access Journals (Sweden)

WANG, Z.

2012-02-01

Full Text Available Multivariate statistical analysis is an effective tool to finish the fault location for electric power system. In Bayesian discriminant analysis as a subbranch, by the research of several populations, one can calculate the conditional probability that some samples belong to these populations, and compare the corresponding probability. The sample will be classified as population with maximum probability. In this paper, based on Bayesian discriminant analysis principle, a great number of simulation examples have confirmed that the results of Bayesian fault discriminant in wide area backup protection are accurate and reliable.

Linear Time Varying Approach to Satellite Attitude Control Using only Electromagnetic Actuation

DEFF Research Database (Denmark)

Wisniewski, Rafal

1997-01-01

, lightweight, and power efficient actuators is therefore crucial and viable. This paper discusses linear attitude control strategies for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. The principle is to use the interaction between the Earth's magnetic field...... systems is limited, nevertheless, a solution of the Riccati equation gives an excellent frame for investigations provided in this paper. An observation that geomagnetic field changes approximately periodically when a satellite is on a near polar orbit is used throughout this paper. Three types of attitude...... controllers are proposed: an infinite horizon, a finite horizon, and a constant gain controller. Their performance is evaluated and compared in the simulation study of the realistic environment....

Linear Time Varying Approach to Satellite Attitude Control Using only Electromagnetic Actuation

DEFF Research Database (Denmark)

Wisniewski, Rafal

2000-01-01

, lightweight, and power efficient actuators is therefore crucial and viable. This paper discusser linear attitude control strategies for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. The principle is to use the interaction between the Earth's magnetic field......, nevertheless, a solution of the riccati equation gives an excellent frame for investigations provided in this paper. An observation that geomagnetic field changes approximately periodically when satellite is on a near polar orbit is used throughout this paper. Three types of attitude controllers are proposed......: an infinite horizon, a finite horizon, and a constant gain controller. Their performance is evaluated and compared in the simulation study of the environment...

Secure, Autonomous, Intelligent Controller for Integrating Distributed Emergency Response Satellite Operations

Science.gov (United States)

Ivancic, William D.; Paulsen, Phillip E.; Miller, Eric M.; Sage, Steen P.

2013-01-01

This report describes a Secure, Autonomous, and Intelligent Controller for Integrating Distributed Emergency Response Satellite Operations. It includes a description of current improvements to existing Virtual Mission Operations Center technology being used by US Department of Defense and originally developed under NASA funding. The report also highlights a technology demonstration performed in partnership with the United States Geological Service for Earth Resources Observation and Science using DigitalGlobe(Registered TradeMark) satellites to obtain space-based sensor data.

Drag-Free Motion Control of Satellite for High-Precision Gravity Field Mapping

DEFF Research Database (Denmark)

Ziegler, Bent Lindvig; Blanke, Mogens

2002-01-01

High precision mapping of the geoid and the Earth's gravity field are of importance to a wide range of ongoing studies in areas like ocean circulation, solid Earth physics and ice sheet dynamics. Using a satellite in orbit around the Earth gives the opportunity to map the Earth's gravity field in 3...... will compromise measurement accuracy, unless they are accurately compensated by on-board thrusters. The paper concerns the design of a control system to performing such delicate drag compensation. A six degrees-of-freedom model for the satellite is developed with the model including dynamics of the satellite...

Magnetic dipole moment estimation and compensation for an accurate attitude control in nano-satellite missions

Science.gov (United States)

Inamori, Takaya; Sako, Nobutada; Nakasuka, Shinichi

2011-06-01

Nano-satellites provide space access to broader range of satellite developers and attract interests as an application of the space developments. These days several new nano-satellite missions are proposed with sophisticated objectives such as remote-sensing and observation of astronomical objects. In these advanced missions, some nano-satellites must meet strict attitude requirements for obtaining scientific data or images. For LEO nano-satellite, a magnetic attitude disturbance dominates over other environmental disturbances as a result of small moment of inertia, and this effect should be cancelled for a precise attitude control. This research focuses on how to cancel the magnetic disturbance in orbit. This paper presents a unique method to estimate and compensate the residual magnetic moment, which interacts with the geomagnetic field and causes the magnetic disturbance. An extended Kalman filter is used to estimate the magnetic disturbance. For more practical considerations of the magnetic disturbance compensation, this method has been examined in the PRISM (Pico-satellite for Remote-sensing and Innovative Space Missions). This method will be also used for a nano-astrometry satellite mission. This paper concludes that use of the magnetic disturbance estimation and compensation are useful for nano-satellites missions which require a high accurate attitude control.

The artificial satellite observation chronograph controlled by single chip microcomputer.

Science.gov (United States)

Pan, Guangrong; Tan, Jufan; Ding, Yuanjun

1991-06-01

The instrument specifications, hardware structure, software design, and other characteristics of the chronograph mounting on a theodolite used for artificial satellite observation are presented. The instrument is a real time control system with a single chip microcomputer.

Observations on the Reliability of Rubidium Frequency Standards on Block 2/2A GPS Satellites

Science.gov (United States)

Dieter, Gary L.

1996-01-01

Currently, the block 2/2A Global Positioning System (GPS) satellites are equipped with two rubidium frequency standards. These frequency standards were originally intended to serve as the back-ups to two cesium frequency standards. As the constellation ages, the master Control Station is forced to initialize and increasing number or rubidium frequency standards. Unfortunately the operational use of these frequency standards has not lived up to initial expectations. Although the performance of these rubidium frequency standards has met and even exceeded GPS requirements, their reliability has not. The number of unscheduled outage times and the short operational lifetimes of the rubidium frequency standards compare poorly to the track record of the cesium frequency standards. Only a small number of rubidium frequency standards have actually been made operational. Of these, a large percentage have exhibited poor reliability. If this trend continues, it is unlikely that the rubidium frequency standards will help contribute to the navigation payload meeting program specification.

Groebner Basis Solutions to Satellite Trajectory Control by Pole Placement

Science.gov (United States)

Kukelova, Z.; Krsek, P.; Smutny, V.; Pajdla, T.

2013-09-01

Satellites play an important role, e.g., in telecommunication, navigation and weather monitoring. Controlling their trajectories is an important problem. In [1], an approach to the pole placement for the synthesis of a linear controller has been presented. It leads to solving five polynomial equations in nine unknown elements of the state space matrices of a compensator. This is an underconstrained system and therefore four of the unknown elements need to be considered as free parameters and set to some prior values to obtain a system of five equations in five unknowns. In [1], this system was solved for one chosen set of free parameters with the help of Dixon resultants. In this work, we study and present Groebner basis solutions to this problem of computation of a dynamic compensator for the satellite for different combinations of input free parameters. We show that the Groebner basis method for solving systems of polynomial equations leads to very simple solutions for all combinations of free parameters. These solutions require to perform only the Gauss-Jordan elimination of a small matrix and computation of roots of a single variable polynomial. The maximum degree of this polynomial is not greater than six in general but for most combinations of the input free parameters its degree is even lower. [1] B. Palancz. Application of Dixon resultant to satellite trajectory control by pole placement. Journal of Symbolic Computation, Volume 50, March 2013, Pages 79-99, Elsevier.

Heuristic methods for single link shared backup path protection

DEFF Research Database (Denmark)

Haahr, Jørgen Thorlund; Stidsen, Thomas Riis; Zachariasen, Martin

2014-01-01

schemes are employed. In contrast to manual intervention, automatic protection schemes such as shared backup path protection (SBPP) can recover from failure quickly and efficiently. SBPP is a simple but efficient protection scheme that can be implemented in backbone networks with technology available...... heuristic algorithms and lower bound methods for the SBPP planning problem. Experimental results show that the heuristic algorithms are able to find good quality solutions in minutes. A solution gap of less than 3.5 % was achieved for 5 of 7 benchmark instances (and a gap of less than 11 % for the remaining...

An up-link power control for demand assignment International Business Satellite Communications Network

Science.gov (United States)

Nohara, Mitsuo; Takeuchi, Yoshio; Takahata, Fumio

Up-link power control (UPC) is one of the essential technologies to provide efficient satellite communication systems operated at frequency bands above 10 GHz. A simple and cost-effective UPC scheme applicable to a demand assignment international business satellite communications system has been developed. This paper presents the UPC scheme, including the hardware implementation and its performance.

Satellite technology and the control of parasitic diseases in Africa ...

African Journals Online (AJOL)

The potential application of these techniques in the surveillance, control and prevention of parasitic diseases in Africa is explored in this write-up. Keywords: surveillance, parasitic diseases, satellite techniques, remote sensing, Geographical Information System (GIS), Global Positioning Sytem (GPS), human and robotic, ...

77 FR 70421 - GPS Satellite Simulator Control Working Group Meeting

Science.gov (United States)

2012-11-26

... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Space and Missile Systems Center, Global Positioning Systems (GPS) Directorate, Department of the Air Force, DoD. ACTION: Meeting Notice. SUMMARY: This meeting notice is to inform GPS...

Lithium Ion Battery Chemistries from Renewable Energy Storage to Automotive and Back-up Power Applications

DEFF Research Database (Denmark)

Stan, Ana-Irina; Swierczynski, Maciej Jozef; Stroe, Daniel Ioan

2014-01-01

Lithium ion (Li-ion) batteries have been extensively used in consumer electronics because of their characteristics, such as high efficiency, long life, and high gravimetric and volumetric energy. In addition, Li-ion batteries are becoming the most attractive candidate as electrochemical storage...... systems for stationary applications, as well as power source for sustainable automotive and back-up power supply applications. This paper gives an overview of the Li-ion battery chemistries that are available at present in the market, and describes the three out of four main applications (except...... the consumers’ applications), grid support, automotive, and back-up power, for which the Li-ion batteries are suitable. Each of these applications has its own specifications and thus, the chemistry of the Li-ion battery should be chosen to fulfil the requirements of the corresponding application. Consequently...

Tracer techniques for urine volume determination and urine collection and sampling back-up system

Science.gov (United States)

Ramirez, R. V.

1971-01-01

The feasibility, functionality, and overall accuracy of the use of lithium were investigated as a chemical tracer in urine for providing a means of indirect determination of total urine volume by the atomic absorption spectrophotometry method. Experiments were conducted to investigate the parameters of instrumentation, tracer concentration, mixing times, and methods for incorporating the tracer material in the urine collection bag, and to refine and optimize the urine tracer technique to comply with the Skylab scheme and operational parameters of + or - 2% of volume error and + or - 1% accuracy of amount of tracer added to each container. In addition, a back-up method for urine collection and sampling system was developed and evaluated. This back-up method incorporates the tracer technique for volume determination in event of failure of the primary urine collection and preservation system. One chemical preservative was selected and evaluated as a contingency chemical preservative for the storage of urine in event of failure of the urine cooling system.

The Unparalleled Systems Engineering of MSL's Backup Entry, Descent, and Landing System: Second Chance

Science.gov (United States)

Roumeliotis, Chris; Grinblat, Jonathan; Reeves, Glenn

2013-01-01

Second Chance (SECC) was a bare bones version of Mars Science Laboratory's (MSL) Entry Descent & Landing (EDL) flight software that ran on Curiosity's backup computer, which could have taken over swiftly in the event of a reset of Curiosity's prime computer, in order to land her safely on Mars. Without SECC, a reset of Curiosity's prime computer would have lead to catastrophic mission failure. Even though a reset of the prime computer never occurred, SECC had the important responsibility as EDL's guardian angel, and this responsibility would not have seen such success without unparalleled systems engineering. This paper will focus on the systems engineering behind SECC: Covering a brief overview of SECC's design, the intense schedule to use SECC as a backup system, the verification and validation of the system's "Do No Harm" mandate, the system's overall functional performance, and finally, its use on the fateful day of August 5th, 2012.

78 FR 63459 - GPS Satellite Simulator Control Working Group Meeting

Science.gov (United States)

2013-10-24

... DEPARTMENT OF DEFENSE Air Force GPS Satellite Simulator Control Working Group Meeting AGENCY: Department of the Air Force. ACTION: Meeting Notice. SUMMARY: This meeting notice is to inform GPS simulator manufacturers, who supply products to the Department of Defense (DoD), and GPS simulator users, both government...

Performance model to assist solar thermal power plant siting in northern Chile based on backup fuel consumption

Energy Technology Data Exchange (ETDEWEB)

Larrain, Teresita; Escobar, Rodrigo; Vergara, Julio [Departamento de Ingenieria Mecanica y Metalurgica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, Macul, Santiago (Chile)

2010-08-15

In response to environmental awareness, Chile introduced sustainability goals in its electricity law. Power producers must deliver 5% from renewable sources by 2010 and 10% by 2024. The Chilean desert has a large available surface with one of the highest radiation levels and clearest skies in the World. These factors imply that solar power is an option for this task. However, a commercial plant requires a fossil fuel system to backup the sunlight intermittency. The authors developed a thermodynamical model to estimate the backup fraction needed in a 100 MW hybrid -solar-fossil- parabolic trough power plant. This paper presents the model aiming to predicting the performance and exploring its usefulness in assisting site selection among four locations. Since solar radiation data are only available in a monthly average, we introduced two approaches to feed the model. One data set provided an average month with identical days throughout and the other one considered an artificial month of different daylight profiles on an hourly basis for the same monthly average. We recommend a best plant location based on minimum fossil fuel backup, contributing to optimal siting from the energy perspective. Utilities will refine their policy goals more closely when a precise solar energy data set becomes available. (author)

A Topology Control Strategy with Reliability Assurance for Satellite Cluster Networks in Earth Observation.

Science.gov (United States)

Chen, Qing; Zhang, Jinxiu; Hu, Ze

2017-02-23

This article investigates the dynamic topology control problemof satellite cluster networks (SCNs) in Earth observation (EO) missions by applying a novel metric of stability for inter-satellite links (ISLs). The properties of the periodicity and predictability of satellites' relative position are involved in the link cost metric which is to give a selection criterion for choosing the most reliable data routing paths. Also, a cooperative work model with reliability is proposed for the situation of emergency EO missions. Based on the link cost metric and the proposed reliability model, a reliability assurance topology control algorithm and its corresponding dynamic topology control (RAT) strategy are established to maximize the stability of data transmission in the SCNs. The SCNs scenario is tested through some numeric simulations of the topology stability of average topology lifetime and average packet loss rate. Simulation results show that the proposed reliable strategy applied in SCNs significantly improves the data transmission performance and prolongs the average topology lifetime.

78 FR 67132 - GPS Satellite Simulator Control Working Group Meeting

Science.gov (United States)

2013-11-08

... DEPARTMENT OF DEFENSE Department of the Air Force GPS Satellite Simulator Control Working Group... simulator manufacturers, who supply products to the Department of Defense (DoD), and GPS simulator users..., and email address) to [email protected]us.af.mil and have your security personnel submit your VAR...

Development of a hardware-in-loop attitude control simulator for a CubeSat satellite

Science.gov (United States)

Tapsawat, Wittawat; Sangpet, Teerawat; Kuntanapreeda, Suwat

2018-01-01

Attitude control is an important part in satellite on-orbit operation. It greatly affects the performance of satellites. Testing of an attitude determination and control subsystem (ADCS) is very challenging since it might require attitude dynamics and space environment in the orbit. This paper develops a low-cost hardware-in-loop (HIL) simulator for testing an ADCS of a CubeSat satellite. The simulator consists of a numerical simulation part, a hardware part, and a HIL interface hardware unit. The numerical simulation part includes orbital dynamics, attitude dynamics and Earth’s magnetic field. The hardware part is the real ADCS board of the satellite. The simulation part outputs satellite’s angular velocity and geomagnetic field information to the HIL interface hardware. Then, based on this information, the HIL interface hardware generates I2C signals mimicking the signals of the on-board rate-gyros and magnetometers and consequently outputs the signals to the ADCS board. The ADCS board reads the rate-gyro and magnetometer signals, calculates control signals, and drives the attitude actuators which are three magnetic torquers (MTQs). The responses of the MTQs sensed by a separated magnetometer are feedback to the numerical simulation part completing the HIL simulation loop. Experimental studies are conducted to demonstrate the feasibility and effectiveness of the simulator.

Development and control of a three-axis satellite simulator for the bifocal relay mirror initiative

OpenAIRE

Chernesky, Vincent S.

2001-01-01

The Three Axis Satellite Simulator (TASS) is a 4-foot diameter octagonal platform supported on a spherical air bearing. The platform hosts several satellite subsystems, including rate gyros, reaction wheels, thrusters, sun sensors, and an onboard control computer. This free-floating design allows for realistic emulation of satellite attitude dynamics in a laboratory environment. The bifocal relay mirror spacecraft system is composed of two optically coupled telescopes used to redirect the las...

Detumbling control for kinematically redundant space manipulator post-grasping a rotational satellite

Science.gov (United States)

Wang, Mingming; Luo, Jianjun; Yuan, Jianping; Walter, Ulrich

2017-12-01

The objective of this paper is to establish a detumbling strategy and a coordination control scheme for a kinematically redundant space manipulator post-grasping a rotational satellite. First, the dynamics of the kinematically redundant space robot after grasping the target is presented, which lays the foundation for the coordination controller design. Subsequently, optimal detumbling and motion planning strategy for the post-capture phase is proposed based on the quartic Bézier curves and adaptive differential evolution (DE) algorithm subject to the specific constraints. Both detumbling time and control torques are taken into account for the generation of the optimal detumbling strategy. Furthermore, a coordination control scheme is presented to track the designed reference path while regulating the attitude of the chaser to a desired value, which successfully dumps the initial angular velocity of the rotational satellite and controls the base attitude synchronously. Simulation results are presented for detumbling a target with rotational motion using a 7 degree-of-freedom (DOF) redundant space manipulator, which demonstrates the effectiveness of the proposed method.

On the nonlinear dynamics of two types of backup bearings - Theoretical and experimental aspects

DEFF Research Database (Denmark)

Lahriri, Said; Santos, Ilmar F.; Weber, Hans I.

2012-01-01

mass unbalance, instabilities generated by aerodynamic and hydrodynamic forces in seals and bearings among others. The contact event gives rise to normal and friction forces exerted on the rotor at impact events. The friction force plays a significant role by transferring some rotational energy...... bearing (annular guide) and for the new disk-pin backup bearing. For the conventional annular guide setup, it is reasonable to superpose an impact condition to the rub, where the rotor spin energy can be fully transformed into rotor lateral movements. Using a nonideal drive, i.e., an electric motor...... without any kind of velocity feedback control, it is even possible to almost stop the rotor spin under rubbing conditions. All the rotational energy will be transformed in a kind of self-excited rotor lateral vibration with repeated impacts against the housing. The vibration of the housing is coupled...

Optimizing the Attitude Control of Small Satellite Constellations for Rapid Response Imaging

Science.gov (United States)

Nag, S.; Li, A.

2016-12-01

Distributed Space Missions (DSMs) such as formation flight and constellations, are being recognized as important solutions to increase measurement samples over space and time. Given the increasingly accurate attitude control systems emerging in the commercial market, small spacecraft now have the ability to slew and point within few minutes of notice. In spite of hardware development in CubeSats at the payload (e.g. NASA InVEST) and subsystems (e.g. Blue Canyon Technologies), software development for tradespace analysis in constellation design (e.g. Goddard's TAT-C), planning and scheduling development in single spacecraft (e.g. GEO-CAPE) and aerial flight path optimizations for UAVs (e.g. NASA Sensor Web), there is a gap in open-source, open-access software tools for planning and scheduling distributed satellite operations in terms of pointing and observing targets. This paper will demonstrate results from a tool being developed for scheduling pointing operations of narrow field-of-view (FOV) sensors over mission lifetime to maximize metrics such as global coverage and revisit statistics. Past research has shown the need for at least fourteen satellites to cover the Earth globally everyday using a LandSat-like sensor. Increasing the FOV three times reduces the need to four satellites, however adds image distortion and BRDF complexities to the observed reflectance. If narrow FOV sensors on a small satellite constellation were commanded using robust algorithms to slew their sensor dynamically, they would be able to coordinately cover the global landmass much faster without compensating for spatial resolution or BRDF effects. Our algorithm to optimize constellation satellite pointing is based on a dynamic programming approach under the constraints of orbital mechanics and existing attitude control systems for small satellites. As a case study for our algorithm, we minimize the time required to cover the 17000 Landsat images with maximum signal to noise ratio fall

Control of peripheral units by satellite computer

International Nuclear Information System (INIS)

Tran, K.T.

1974-01-01

A computer system was developed allowing the control of nuclear physics experiments, and use of the results by means of graphical and conversational assemblies. This system which is made of two computers, one IBM-370/135 and one Telemecanique Electrique T1600, controls the conventional IBM peripherals and also the special ones made in the laboratory, such as data acquisition display and graphics units. The visual display is implemented by a scanning-type television, equipped with a light-pen. These units in themselves are universal, but their specifications were established to meet the requirements of nuclear physics experiments. The input-output channels of the two computers have been connected together by an interface, designed and implemented in the Laboratory. This interface allows the exchange of control signals and data (the data are changed from bytes into word and vice-versa). The T1600 controls the peripherals mentionned above according to the commands of the IBM370. Hence the T1600 has here the part of a satellite computer which allows conversation with the main computer and also insures the control of its special peripheral units [fr

Backup key generation model for one-time password security protocol

Science.gov (United States)

Jeyanthi, N.; Kundu, Sourav

2017-11-01

The use of one-time password (OTP) has ushered new life into the existing authentication protocols used by the software industry. It introduced a second layer of security to the traditional username-password authentication, thus coining the term, two-factor authentication. One of the drawbacks of this protocol is the unreliability of the hardware token at the time of authentication. This paper proposes a simple backup key model that can be associated with the real world applications’user database, which would allow a user to circumvent the second authentication stage, in the event of unavailability of the hardware token.

A high precision dual feedback discrete control system designed for satellite trajectory simulator

Science.gov (United States)

Liu, Ximin; Liu, Liren; Sun, Jianfeng; Xu, Nan

2005-08-01

Cooperating with the free-space laser communication terminals, the satellite trajectory simulator is used to test the acquisition, pointing, tracking and communicating performances of the terminals. So the satellite trajectory simulator plays an important role in terminal ground test and verification. Using the double-prism, Sun etc in our group designed a satellite trajectory simulator. In this paper, a high precision dual feedback discrete control system designed for the simulator is given and a digital fabrication of the simulator is made correspondingly. In the dual feedback discrete control system, Proportional- Integral controller is used in velocity feedback loop and Proportional- Integral- Derivative controller is used in position feedback loop. In the controller design, simplex method is introduced and an improvement to the method is made. According to the transfer function of the control system in Z domain, the digital fabrication of the simulator is given when it is exposed to mechanism error and moment disturbance. Typically, when the mechanism error is 100urad, the residual standard error of pitching angle, azimuth angle, x-coordinate position and y-coordinate position are 0.49urad, 6.12urad, 4.56urad, 4.09urad respectively. When the moment disturbance is 0.1rad, the residual standard error of pitching angle, azimuth angle, x-coordinate position and y-coordinate position are 0.26urad, 0.22urad, 0.16urad, 0.15urad respectively. The digital fabrication results demonstrate that the dual feedback discrete control system designed for the simulator can achieve the anticipated high precision performance.

Tether dynamics and control results for tethered satellite system's initial flight

Science.gov (United States)

Chapel, Jim D.; Flanders, Howard

The recent Tethered Satellite System-1 (TSS-1) mission has provided a wealth of data concerning the dynamics of tethered systems in space and has demonstrated the effectiveness of operational techniques designed to control these dynamics. In this paper, we review control techniques developed for managing tether dynamics, and discuss the results of using these techniques for the Tethered Satellite System's maiden flight on STS-46. In particular, the flight results of controlling libration dynamics, string dynamics, and slack tether are presented. These results show that tether dynamics can be safely managed. The overall stability of the system was found to be surprisingly good even at relatively short tether lengths. In fact, the system operated in passive mode at a tether length of 256 meters for over 9 hours. Only monitoring of the system was required during this time. Although flight anomalies prevented the planned deployment to 20 km, the extended operations at shorter tether lengths have proven the viability of using tethers in space. These results should prove invaluable in preparing for future missions with tethered objects in space.

Backup of renewable energy for an electrical island: case study of Israeli electricity system--current status.

Science.gov (United States)

Fakhouri, A; Kuperman, A

2014-01-01

The paper focuses on the quantitative analysis of Israeli Government's targets of 10% renewable energy penetration by 2020 and determining the desired methodology (models) for assessing the effects on the electricity market, addressing the fact that Israel is an electricity island. The main objective is to determine the influence of achieving the Government's goals for renewable energy penetration on the need for backup in the Israeli electricity system. This work presents the current situation of the Israeli electricity market and the study to be taken in order to assess the undesirable effects resulting from the intermittency of electricity generated by wind and solar power stations as well as presents some solutions to mitigating these phenomena. Future work will focus on a quantitative analysis of model runs and determine the amounts of backup required relative to the amount of installed capacity from renewable resources.

77 FR 28797 - Redundancy of Communications Systems: Backup Power Private Land Mobile Radio Services: Selection...

Science.gov (United States)

2012-05-16

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Parts 12 and 90 [DA 11-1838] Redundancy of Communications Systems: Backup Power Private Land Mobile Radio Services: Selection and Assignment of Frequencies, and Transition of the Upper 200 Channels in the 800 MHz Band to EA Licensing AGENCY: Federal Communications...

Discussions on attitude determination and control system for micro/nano/pico-satellites considering survivability based on Hodoyoshi-3 and 4 experiences

Science.gov (United States)

Nakasuka, Shinichi; Miyata, Kikuko; Tsuruda, Yoshihiro; Aoyanagi, Yoshihide; Matsumoto, Takeshi

2018-04-01

The recent advancement of micro/nano/pico-satellites technologies encourages many universities to develop three axis stabilized satellites. As three axis stabilization is high level technology requiring the proper functioning of various sensors, actuators and control software, many early satellites failed in their initial operation phase because of shortage of solar power generation or inability to realize the initial step of missions because of unexpected attitude control system performance. These results come from failure to design the satellite attitude determination and control system (ADCS) appropriately and not considering "satellite survivability." ADCS should be designed such that even if some sensors or actuators cannot work as expected, the satellite can survive and carry out some of its missions, even if not full. This paper discusses how to realize ADCS while taking satellite survivability into account, based on our experiences of design and in-orbit operations of Hodoyoshi-3 and 4 satellites launched in 2014, which suffered from various component anomalies but could complete their missions.

Sensor fault detection and recovery in satellite attitude control

Science.gov (United States)

Nasrolahi, Seiied Saeed; Abdollahi, Farzaneh

2018-04-01

This paper proposes an integrated sensor fault detection and recovery for the satellite attitude control system. By introducing a nonlinear observer, the healthy sensor measurements are provided. Considering attitude dynamics and kinematic, a novel observer is developed to detect the fault in angular rate as well as attitude sensors individually or simultaneously. There is no limit on type and configuration of attitude sensors. By designing a state feedback based control signal and Lyapunov stability criterion, the uniformly ultimately boundedness of tracking errors in the presence of sensor faults is guaranteed. Finally, simulation results are presented to illustrate the performance of the integrated scheme.

On the nonlinear dynamics of two types of backup bearings - Theoretical and experimental aspects

DEFF Research Database (Denmark)

Lahriri, Said; Santos, Ilmar; Hartmann, Henning

2012-01-01

sudden mass unbalance, instabilities generated by aerodynamic and hydrodynamic forces in seals and bearings among others. The contact event gives rise to normal and friction forces exerted on the rotor at impact events. The friction force plays a significant role by transferring some rotational energy...... bearing (annular guide) as well for the new disk-pin backup bearing. For the conventional annular guide setup, it is reasonable to superpose an impact condition to the rub, where the rotor spin energy can be fully transformed into rotor lateral movements. Using a non ideal drive, i.e. an electric motor...... without any kind of velocity feedback control, it is even possible to almost stop the rotor spin under rubbing conditions. All the rotational energy will be transformed in a kind of "self-excited" rotor lateral vibration with repeated impacts against the housing. The vibration of the housing is coupled...

Backup of Renewable Energy for an Electrical Island: Case Study of Israeli Electricity System—Current Status

Science.gov (United States)

Fakhouri, A.; Kuperman, A.

2014-01-01

The paper focuses on the quantitative analysis of Israeli Government's targets of 10% renewable energy penetration by 2020 and determining the desired methodology (models) for assessing the effects on the electricity market, addressing the fact that Israel is an electricity island. The main objective is to determine the influence of achieving the Government's goals for renewable energy penetration on the need for backup in the Israeli electricity system. This work presents the current situation of the Israeli electricity market and the study to be taken in order to assess the undesirable effects resulting from the intermittency of electricity generated by wind and solar power stations as well as presents some solutions to mitigating these phenomena. Future work will focus on a quantitative analysis of model runs and determine the amounts of backup required relative to the amount of installed capacity from renewable resources. PMID:24624044

Semi-active Attitude Control and Off-line Attitude Determination for the SEETI-Express Student Micro-satellite

DEFF Research Database (Denmark)

Alminde, Lars

This paper concerns the development of the Attitude Determination and Control System (ADCS) for the SSETI-Express micro-satellite mission. The mission is an educational project involving 14 universities and the European Space Agency (ESA). The satellite has been designed and built, by students...

Semi-active Attitude Control and Off-line Attitude Determination for the SSETI-Express Student Micro-satellite

DEFF Research Database (Denmark)

Alminde, Lars

2005-01-01

This paper concerns the development of the Attitude Determination and Control System (ADCS) for the SSETI-Express micro-satellite mission. The mission is an educational project involving 14 universities and the European Space Agency (ESA). The satellite has been designed and built, by students...

3-Axis magnetic control: flight results of the TANGO satellite in the PRISMA mission

Science.gov (United States)

Chasset, C.; Noteborn, R.; Bodin, P.; Larsson, R.; Jakobsson, B.

2013-09-01

PRISMA implements guidance, navigation and control strategies for advanced formation flying and rendezvous experiments. The project is funded by the Swedish National Space Board and run by OHB-Sweden in close cooperation with DLR, CNES and the Danish Technical University. The PRISMA test bed consists of a fully manoeuvrable MANGO satellite as well as a 3-axis controlled TANGO satellite without any Δ V capability. PRISMA was launched on the 15th of June 2010 on board DNEPR. The TANGO spacecraft is the reference satellite for the experiments performed by MANGO, either with a "cooperative" or "non-cooperative" behaviour. Small, light and low-cost were the keywords for the TANGO design. The attitude determination is based on Sun sensors and magnetometers, and the active attitude control uses magnetic torque rods only. In order to perform the attitude manoeuvres required to fulfil the mission objectives, using any additional gravity gradient boom to passively stabilize the spacecraft was not allowed. After a two-month commissioning phase, TANGO separated from MANGO on the 11th of August 2010. All operational modes have been successfully tested, and the pointing performance in flight is in accordance with expectations. The robust Sun Acquisition mode reduced the initial tip-off rate and placed TANGO into a safe attitude in MANGO. At the same time, it points its solar panel towards the Sun, and all payload equipments can be switched on without any restriction. This paper gives an overview of the TANGO Attitude Control System design. It then presents the flight results in the different operating modes. Finally, it highlights the key elements at the origin of the successful 3-axis magnetic control strategy on the TANGO satellite.

Multiple Model Adaptive Attitude Control of LEO Satellite with Angular Velocity Constraints

Science.gov (United States)

Shahrooei, Abolfazl; Kazemi, Mohammad Hosein

2018-04-01

In this paper, the multiple model adaptive control is utilized to improve the transient response of attitude control system for a rigid spacecraft. An adaptive output feedback control law is proposed for attitude control under angular velocity constraints and its almost global asymptotic stability is proved. The multiple model adaptive control approach is employed to counteract large uncertainty in parameter space of the inertia matrix. The nonlinear dynamics of a low earth orbit satellite is simulated and the proposed control algorithm is implemented. The reported results show the effectiveness of the suggested scheme.

A Comparative Study of Actuator Configurations for Satellite Attitude Control

Directory of Open Access Journals (Sweden)

Raymond Kristiansen

2005-10-01

Full Text Available In this paper a controllability study of different actuator configurations consisting of magnetic torquers, reaction wheels and a gravity boom is presented. The theoretical analysis is performed with use of controllability gramians, and simulation results with the different configurations are presented and compared regarding settling time and power consumption to substantiate the theoretical analysis. A reference model is also introduced to show how the power consumption can he lowered to the same magnitude as when magnetic torquers are used, without degrading the satellite response significantly.

Fuel Cell Backup Power Unit Configuration and Electricity Market Participation: A Feasibility Study

Energy Technology Data Exchange (ETDEWEB)

Ma, Zhiwen [National Renewable Energy Lab. (NREL), Golden, CO (United States); Eichman, Josh [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kurtz, Jennifer [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2017-03-13

This National Renewable Energy Laboratory industry-inspired Laboratory Directed Research and Development project evaluates the feasibility and economics of using fuel cell backup power systems in cell towers to provide grid services (e.g., balancing, ancillary services, demand response). The work is intended to evaluate the integration of thousands of under-utilized, clean, efficient, and reliable fuel cell systems that are already installed in cell towers for potential grid and ancillary services.

A semi-physical simulation platform of attitude determination and control system for satellite

Directory of Open Access Journals (Sweden)

Yuanjin Yu

2016-05-01

Full Text Available A semi-physical simulation platform for attitude determination and control system is proposed to verify the attitude estimator and controller on ground. A simulation target, a host PC, many attitude sensors, and actuators compose the simulation platform. The simulation target is composed of a central processing unit board with VxWorks operating system and many input/output boards connected via Compact Peripheral Component Interconnect bus. The executable programs in target are automatically generated from the simulation models in Simulink based on Real-Time Workshop of MATLAB. A three-axes gyroscope, a three-axes magnetometer, a sun sensor, a star tracer, three flywheels, and a Global Positioning System receiver are connected to the simulation target, which formulates the attitude control cycle of a satellite. The simulation models of the attitude determination and control system are described in detail. Finally, the semi-physical simulation platform is used to demonstrate the availability and rationality of the control scheme of a micro-satellite. Comparing the results between the numerical simulation in Simulink and the semi-physical simulation, the semi-physical simulation platform is available and the control scheme successfully achieves three-axes stabilization.

Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

Science.gov (United States)

Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

2013-01-01

In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

RELAP5-3D Resolution of Known Restart/Backup Issues

Energy Technology Data Exchange (ETDEWEB)

Mesina, George L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Anderson, Nolan A. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2014-12-01

The state-of-the-art nuclear reactor system safety analysis computer program developed at the Idaho National Laboratory (INL), RELAP5-3D, continues to adapt to changes in computer hardware and software and to develop to meet the ever-expanding needs of the nuclear industry. To continue at the forefront, code testing must evolve with both code and industry developments, and it must work correctly. To best ensure this, the processes of Software Verification and Validation (V&V) are applied. Verification compares coding against its documented algorithms and equations and compares its calculations against analytical solutions and the method of manufactured solutions. A form of this, sequential verification, checks code specifications against coding only when originally written then applies regression testing which compares code calculations between consecutive updates or versions on a set of test cases to check that the performance does not change. A sequential verification testing system was specially constructed for RELAP5-3D to both detect errors with extreme accuracy and cover all nuclear-plant-relevant code features. Detection is provided through a “verification file” that records double precision sums of key variables. Coverage is provided by a test suite of input decks that exercise code features and capabilities necessary to model a nuclear power plant. A matrix of test features and short-running cases that exercise them is presented. This testing system is used to test base cases (called null testing) as well as restart and backup cases. It can test RELAP5-3D performance in both standalone and coupled (through PVM to other codes) runs. Application of verification testing revealed numerous restart and backup issues in both standalone and couple modes. This document reports the resolution of these issues.

Research of remote control for Chinese Antarctica Telescope based on iridium satellite communication

Science.gov (United States)

Xu, Lingzhe; Yang, Shihai

2010-07-01

Astronomers are ever dreaming of sites with best seeing on the Earth surface for celestial observation, and the Antarctica is one of a few such sites only left owing to the global air pollution. However, Antarctica region is largely unaccessible for human being due to lacking of fundamental living conditions, travel facilities and effective ways of communication. Worst of all, the popular internet source as a general way of communication scarcely exists there. Facing such a dilemma and as a solution remote control and data transmission for telescopes through iridium satellite communication has been put forward for the Chinese network Antarctic Schmidt Telescopes 3 (AST3), which is currently under all round research and development. This paper presents iridium satellite-based remote control application adapted to telescope control. The pioneer work in China involves hardware and software configuration utilizing techniques for reliable and secure communication, which is outlined in the paper too.

Efficient medium access control protocol for geostationary satellite systems

Institute of Scientific and Technical Information of China (English)

王丽娜; 顾学迈

2004-01-01

This paper proposes an efficient medium access control (MAC) protocol based on multifrequency-time division multiple access (MF-TDMA) for geostationary satellite systems deploying multiple spot-beams and onboard processing,which uses a method of random reservation access with movable boundaries to dynamically request the transmission slots and can transmit different types of traffic. The simulation results have shown that our designed MAC protocol can achieve a high bandwidth utilization, while providing the required quality of service (QoS) for each class of service.

Real-time environmental radiation monitoring system with automatic restoration of backup data in site detector via communication using radio frequency

International Nuclear Information System (INIS)

Lee, Wan No; Kim, Eun Han; Chung, Kun Ho; Cho, Young Hyun; Choi, Geun Sik; Lee, Chang Woo; Park, Ki Hyun; Kim, Yun Goo

2003-01-01

An environmental radiation monitoring system based on high pressurized ionization chamber has been used for on-line gamma monitoring surrounding the KAERI (Korea Atomic Energy Research Institute), which transmits the dose data measured from ion chamber on the site via radio frequency to a central processing computer and stores the transmitted real-time data. Although communication using ratio frequency has several advantages such as effective and economical transmission, storage, and data process, there is one main disadvantage that data loss during transmission often happens because of unexpected communication problems. It is possible to restore the loss data by off-line such as floppy disk but the simultaneous process and display of current data as well as the backup data are very difficult in the present on-line system. In this work, a new electronic circuit board and the operation software applicable to the conventional environmental radiation monitoring system are developed and the automatical synchronization of the ion chamber unit and the central processing computer is carried out every day. This system is automatically able to restore the backup data within 34 hours without additional equipment and also display together the current data as well as the transmitted backup data after checking time flag

High-Temperature Polymer Composites Tested for Hypersonic Rocket Combustor Backup Structure

Science.gov (United States)

Sutter, James K.; Shin, E. Eugene; Thesken, John C.; Fink, Jeffrey E.

2005-01-01

Significant component weight reductions are required to achieve the aggressive thrust-toweight goals for the Rocket Based Combined Cycle (RBCC) third-generation, reusable liquid propellant rocket engine, which is one possible engine for a future single-stage-toorbit vehicle. A collaboration between the NASA Glenn Research Center and Boeing Rocketdyne was formed under the Higher Operating Temperature Propulsion Components (HOTPC) program and, currently, the Ultra-Efficient Engine Technology (UEET) Project to develop carbon-fiber-reinforced high-temperature polymer matrix composites (HTPMCs). This program focused primarily on the combustor backup structure to replace all metallic support components with a much lighter polymer-matrixcomposite- (PMC-) titanium honeycomb sandwich structure.

Data Back-Up and Recovery Techniques for Cloud Server Using Seed Block Algorithm

OpenAIRE

R. V. Gandhi; M Seshaiah

2015-01-01

In cloud computing, data generated in electronic form are large in amount. To maintain this data efficiently, there is a necessity of data recovery services. To cater this, we propose a smart remote data backup algorithm, Seed Block Algorithm. The objective of proposed algorithm is twofold; first it help the users to collect information from any remote location in the absence of network connectivity and second to recover the files in case of the file deletion or if the cloud gets ...

Communication and Control in the Canadian North: The Role of Interactive Satellites.

Science.gov (United States)

Valaskakis, Gail G.

In 1972 the Canadian government launched its first domestic communications satellite, Anik A, which relays direct broadcast television and telephone messages to northern communities. The impact of television on Inuit life has raised issues and concerns pertaining to native language broadcasting, media access and control, and cultural identity…

Compact modeling of a telecom back-up unit powered by air-cooled proton exchange membrane fuel cell

DEFF Research Database (Denmark)

Gao, Xin; Kær, Søren Knudsen

2018-01-01

Applications of proton exchange membrane fuel cells (PEMFC’s) are expanding in portable, automotive and stationary markets. One promising application is the back-up power for telecommunication applications in remote areas where usually air-cooled PMEFC’s are used. An air-cooled PEMFC system is much...

A portable backup power supply to assure extended decay heat removal during natural phenomena-induced station blackout

International Nuclear Information System (INIS)

Proctor, L.D.; Merryman, L.D.; Sallee, W.E.

1989-01-01

The High Flux Isotope Reactor (HFIR) is a light water cooled and moderated flux-trap type research reactor located at Oak Ridge National Laboratory (ORNL). Coolant circulation following reactor shutdown is provided by the primary coolant pumps. DC-powered pony motors drive these pumps at a reduced flow rate following shutdown of the normal ac-powered motors. Forced circulation decay heat removal is required for several hours to preclude core damage following shutdown. Recent analyses identified a potential vulnerability due to a natural phenomena-induced station blackout. Neither the offsire power supply nor the onsite emergency diesel generators are designed to withstand the effects of seismic events or tornadoes. It could not be assured that the capacity of the dedicated batteries provided as a backup power supply for the primary coolant pump pony motors is adequate to provide forced circulation cooling for the required time following such events. A portable backup power supply added to the plant to address this potential vulnerability is described

Satellite myths

Science.gov (United States)

Easton, Roger L.; Hall, David

2008-01-01

Richard Corfield's article “Sputnik's legacy” (October 2007 pp23-27) states that the satellite on board the US Vanguard rocket, which exploded during launch on 6 December 1957 two months after Sputnik's successful take-off, was “a hastily put together contraption of wires and circuitry designed only to send a radio signal back to Earth”. In fact, the Vanguard satellite was developed over a period of several years and put together carefully using the best techniques and equipment available at the time - such as transistors from Bell Laboratories/Western Electric. The satellite contained not one but two transmitters, in which the crystal-controlled oscillators had been designed to measure both the temperature of the satellite shell and of the internal package.

GPS Satellite Simulation Facility

Data.gov (United States)

Federal Laboratory Consortium — The GPS satellite simulation facility consists of a GPS satellite simulator controlled by either a Silicon Graphics Origin 2000 or PC depending upon unit under test...

Geostationary satellites collocation

CERN Document Server

Li, Hengnian

2014-01-01

Geostationary Satellites Collocation aims to find solutions for deploying a safe and reliable collocation control. Focusing on the orbital perturbation analysis, the mathematical foundations for orbit and control of the geostationary satellite are summarized. The mathematical and physical principle of orbital maneuver and collocation strategies for multi geostationary satellites sharing with the same dead band is also stressed. Moreover, the book presents some applications using the above algorithms and mathematical models to help readers master the corrective method for planning station keeping maneuvers. Engineers and scientists in the fields of aerospace technology and space science can benefit from this book. Hengnian Li is the Deputy Director of State Key Laboratory of Astronautic Dynamics, China.

Satellite image collection optimization

Science.gov (United States)

Martin, William

2002-09-01

Imaging satellite systems represent a high capital cost. Optimizing the collection of images is critical for both satisfying customer orders and building a sustainable satellite operations business. We describe the functions of an operational, multivariable, time dynamic optimization system that maximizes the daily collection of satellite images. A graphical user interface allows the operator to quickly see the results of what if adjustments to an image collection plan. Used for both long range planning and daily collection scheduling of Space Imaging's IKONOS satellite, the satellite control and tasking (SCT) software allows collection commands to be altered up to 10 min before upload to the satellite.

Satellite navigation—Amazing technology but insidious risk: Why everyone needs to understand space weather

Science.gov (United States)

Hapgood, Mike

2017-04-01

Global navigation satellite systems (GNSS) are one of the technological wonders of the modern world. Popularly known as satellite navigation, these systems have provided global access to precision location and timing services and have thereby stimulated advances in industry and consumer services, including all forms of transport, telecommunications, financial trading, and even the synchronization of power grids. But this wonderful technology is at risk from natural phenomena in the form of space weather. GNSS signals experience a slight delay as they pass through the ionosphere. This delay varies with space weather conditions and is the most significant source of error for GNSS. Scientific efforts to correct these errors have stimulated billions of dollars of investment in systems that provide accurate correction data for suitably equipped GNSS receivers in a growing number of regions around the world. This accuracy is essential for GNSS use by aircraft and ships. Space weather also provides a further occasional but severe risk to GNSS: an extreme space weather event may deny access to GNSS as ionospheric scintillation scrambles the radio signals from satellites, and rapid ionospheric changes outstrip the ability of error correction systems to supply accurate corrections. It is vital that GNSS users have a backup for such occasions, even if it is only to hunker down and weather the storm.

Independent Orbiter Assessment (IOA): Assessment of the backup flight system FMEA/CIL

Science.gov (United States)

Prust, E. E.; Ewell, J. J., Jr.; Hinsdale, L. W.

1988-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Backup Flight System (BFS) hardware, generating draft failure modes and Potential Critical Items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the proposed NASA Post 51-L FMEA/CIL baseline. A resolution of each discrepancy from the comparison is provided through additional analysis as required. This report documents the results of that comparison for the Orbiter BFS hardware. The IOA product for the BFS analysis consisted of 29 failure mode worksheets that resulted in 21 Potential Critical Items (PCI) being identified. This product was originally compared with the proposed NASA BFS baseline and subsequently compared with the applicable Data Processing System (DPS), Electrical Power Distribution and Control (EPD and C), and Displays and Controls NASA CIL items. The comparisons determined if there were any results which had been found by the IOA but were not in the NASA baseline. The original assessment determined there were numerous failure modes and potential critical items in the IOA analysis that were not contained in the NASA BFS baseline. Conversely, the NASA baseline contained three FMEAs (IMU, ADTA, and Air Data Probe) for CIL items that were not identified in the IOA product.

BackUp: Development and evaluation of a smart-phone application for coping with suicidal crises.

Directory of Open Access Journals (Sweden)

Kirsten Pauwels

Full Text Available Suicide is a major public health issue and has large impact on the lives of many people. Innovative technologies such as smartphones could create new possibilities for suicide prevention, such as helping to overcome the barriers and stigma on help seeking in case of suicidal ideation. Due to their omnipresence, smartphone apps can offer suicide prevention tools very fast, they are easily-accessible, low-threshold and can help overcome some of the help-seeking barriers suicidal people experience. This article describes the development, testing and implementation of a mobile application for coping with suicidal crisis: BackUp.Based on the analysis of literature and existing suicide prevention apps several tools were identified as relevant to include in a suicide prevention app. The selected tools (a safety planning tool, a hope box, a coping cards module, and a module to reach out are evidence based in a face to face context, and could be easily transferred into a mobile app. The testing of existing apps and the literature also revealed important guidelines for the technical development of the application.BackUp was developed and tested by an expert panel (n = 9 and a panel of end users (n = 21. Both groups rated BackUp as valuable for suicide prevention. Suicidal ideation of the end user group was measured using the Beck Scale for Suicidal Ideation before and after testing BackUp, and showed a small but non-significant decrease. The majority of the testers used BackUp several times. All tools were evaluated as rather or very useable in times of suicidal crisis.BackUp was positively evaluated and indicates that self-help tools can have a positive impact on suicidal ideation. Apps in particular create opportunities in approaching people that are not reached by traditional interventions; on the other hand they can contribute to suicide prevention in addition to regular care. However, more research is needed on the impact and effect of suicide

Exploring the iPhone Backup made by iTunes

Directory of Open Access Journals (Sweden)

Mario Piccinelli

2011-09-01

Full Text Available The iPhone mobile from Apple Inc. is one of the most notable phones on the market thanks to its simple and user-friendly interface and ever growing pool of available high quality applications for both personal and business use. The increasing use of iPhone mobiles leads forensics practitioners towards the need for tools to access and analyze the information stored in the device. This research aims at describing how to forensically analyze a logical backup of an iPhone made by the Apple iTunes utility, understanding its structure and creating a simple tool to automate the process of decoding and analyzing the data. It was found that significant data of forensic value such as e-mail messages, text and multimedia messages, calendar events, browsing history, GPRS locations, contacts, call history and voicemail recordings can be retrieved using this method of iPhone acquisition.

Nonlinear dynamics of mini-satellite respinup by weak internal controllable torques

Science.gov (United States)

Somov, Yevgeny

2014-12-01

Contemporary space engineering advanced new problem before theoretical mechanics and motion control theory: a spacecraft directed respinup by the weak restricted control internal forces. The paper presents some results on this problem, which is very actual for energy supply of information mini-satellites (for communication, geodesy, radio- and opto-electronic observation of the Earth et al.) with electro-reaction plasma thrusters and gyro moment cluster based on the reaction wheels or the control moment gyros. The solution achieved is based on the methods for synthesis of nonlinear robust control and on rigorous analytical proof for the required spacecraft rotation stability by Lyapunov function method. These results were verified by a computer simulation of strongly nonlinear oscillatory processes at respinuping of a flexible spacecraft.

Nonlinear dynamics of mini-satellite respinup by weak internal controllable torques

Energy Technology Data Exchange (ETDEWEB)

Somov, Yevgeny, E-mail: e-somov@mail.ru [Samara State Technical University, Department for Guidance, Navigation and Control, 244 Molodogvardeyskaya Str., Samara 443100 (Russian Federation)

2014-12-10

Contemporary space engineering advanced new problem before theoretical mechanics and motion control theory: a spacecraft directed respinup by the weak restricted control internal forces. The paper presents some results on this problem, which is very actual for energy supply of information mini-satellites (for communication, geodesy, radio- and opto-electronic observation of the Earth et al.) with electro-reaction plasma thrusters and gyro moment cluster based on the reaction wheels or the control moment gyros. The solution achieved is based on the methods for synthesis of nonlinear robust control and on rigorous analytical proof for the required spacecraft rotation stability by Lyapunov function method. These results were verified by a computer simulation of strongly nonlinear oscillatory processes at respinuping of a flexible spacecraft.

A Topology Control Strategy with Reliability Assurance for Satellite Cluster Networks in Earth Observation

Directory of Open Access Journals (Sweden)

Qing Chen

2017-02-01

Full Text Available This article investigates the dynamic topology control problemof satellite cluster networks (SCNs in Earth observation (EO missions by applying a novel metric of stability for inter-satellite links (ISLs. The properties of the periodicity and predictability of satellites’ relative position are involved in the link cost metric which is to give a selection criterion for choosing the most reliable data routing paths. Also, a cooperative work model with reliability is proposed for the situation of emergency EO missions. Based on the link cost metric and the proposed reliability model, a reliability assurance topology control algorithm and its corresponding dynamic topology control (RAT strategy are established to maximize the stability of data transmission in the SCNs. The SCNs scenario is tested through some numeric simulations of the topology stability of average topology lifetime and average packet loss rate. Simulation results show that the proposed reliable strategy applied in SCNs significantly improves the data transmission performance and prolongs the average topology lifetime.

High Accuracy Attitude Control System Design for Satellite with Flexible Appendages

Directory of Open Access Journals (Sweden)

Wenya Zhou

2014-01-01

Full Text Available In order to realize the high accuracy attitude control of satellite with flexible appendages, attitude control system consisting of the controller and structural filter was designed. When the low order vibration frequency of flexible appendages is approximating the bandwidth of attitude control system, the vibration signal will enter the control system through measurement device to bring impact on the accuracy or even the stability. In order to reduce the impact of vibration of appendages on the attitude control system, the structural filter is designed in terms of rejecting the vibration of flexible appendages. Considering the potential problem of in-orbit frequency variation of the flexible appendages, the design method for the adaptive notch filter is proposed based on the in-orbit identification technology. Finally, the simulation results are given to demonstrate the feasibility and effectiveness of the proposed design techniques.

Using satellite data to guide emission control strategies for surface ozone pollution

Science.gov (United States)

Jin, X.; Fiore, A. M.

2017-12-01

Surface ozone (O3) has adverse effects on public health, agriculture and ecosystems. As a secondary pollutant, ozone is not emitted directly. Ozone forms from two classes of precursors: NOx and VOCs. We use satellite observations of formaldehyde (a marker of VOCs) and NO2 (a marker of NOx) to identify areas which would benefit more from reducing NOx emissions (NOx-limited) versus areas where reducing VOC emissions would lead to lower ozone (VOC-limited). We use a global chemical transport model (GEOS-Chem) to develop a set of threshold values that separate the NOx-limited and VOC-limited conditions. Combining these threshold values with a decadal record of satellite observations, we find that U.S. cities (e.g. New York, Chicago) have shifted from VOC-limited to NOx-limited ozone production regimes in the warm season. This transition reflects the NOx emission controls implemented over the past decade. Increasing NOx sensitivity implies that regional NOx emission control programs will improve O3 air quality more now than it would have a decade ago.

Optimal fault-tolerant control strategy of a solid oxide fuel cell system

Science.gov (United States)

Wu, Xiaojuan; Gao, Danhui

2017-10-01

For solid oxide fuel cell (SOFC) development, load tracking, heat management, air excess ratio constraint, high efficiency, low cost and fault diagnosis are six key issues. However, no literature studies the control techniques combining optimization and fault diagnosis for the SOFC system. An optimal fault-tolerant control strategy is presented in this paper, which involves four parts: a fault diagnosis module, a switching module, two backup optimizers and a controller loop. The fault diagnosis part is presented to identify the SOFC current fault type, and the switching module is used to select the appropriate backup optimizer based on the diagnosis result. NSGA-II and TOPSIS are employed to design the two backup optimizers under normal and air compressor fault states. PID algorithm is proposed to design the control loop, which includes a power tracking controller, an anode inlet temperature controller, a cathode inlet temperature controller and an air excess ratio controller. The simulation results show the proposed optimal fault-tolerant control method can track the power, temperature and air excess ratio at the desired values, simultaneously achieving the maximum efficiency and the minimum unit cost in the case of SOFC normal and even in the air compressor fault.

Kagawa Satellite “STARS” in Shikoku

Science.gov (United States)

Nohmi, Masahiro; Yamamoto, Takeshi; Andatsu, Akira; Takagi, Yohei; Nishikawa, Yusuke; Kaneko, Takashi; Kunitom, Daisuke

The Space Tethered Autonomous Robotic Satellite (STARS) is being developed in Kagawa University, and it will be launched by the H-IIA rocket by Japan Aerospace Exploration Agency (JAXA) in summer 2008. STARS is the first satellite developed in Shikoku, and its specific characteristics are: (i) mother and daughter satellites, which have basic satellite system respectively, and those are launched at the same time; (ii) large space system more than 5m by extending tether; (iii) robotic system, the daughter satellite controls its arm link and the mother satellite controls tether extension. Development of STARS in Kagawa University demonstrates space technology in local community, which has been considered to be a national project. Also, it promotes popularization, enlightenment, and understanding of space technology in local area of the Kagawa prefecture and around it.

Investigation of solar parabolic trough power plants with and without integrated TES (thermal energy storage) and FBS (fuel backup system) using thermic oil and solar salt

International Nuclear Information System (INIS)

Boukelia, T.E.; Mecibah, M.S.; Kumar, B.N.; Reddy, K.S.

2015-01-01

Thermodynamic, economic and environmental analyses of concentrating solar power plants assist in identifying an effective and viable configuration. In this paper, a 4E (energy-exergy-environmental-economic) comparative study of 8 different configurations of parabolic trough solar thermal power plants with two different working fluids (Therminol VP-1 -oil and molten solar salt), with and without integrated thermal energy storage or/and backup fuel system is presented. The results of the comparative study indicate relevant differences among the 8 configurations. The molten solar salt configuration with integrated thermal energy storage and fossil fuel backup system exhibits the highest overall energy efficiency (18.48%) compared to other configurations. Whereas, the highest overall exergy efficiency (21.77%), capacity factor (38.20%) and annual energy generation (114 GWh) are found for the oil based configuration with integrated thermal energy storage and fossil fuel backup system. The results indicate that the configurations based on molten salt are better in terms of environmental and economical parameters. The configurations with integrated thermal energy storage and fossil fuel backup system are found to be techno-economical, but on the other hand are less environment friendly. A detailed comparison of these plants after optimization must be performed before drawing a final conclusion about the best configuration to be adopted in parabolic trough solar thermal power plant. - Highlights: • 4E comparative study of 8 configurations of PTSTPP with two different fluids. • Comparison of the configurations with and without integrated TES (thermal energy storage) and FBS (fuel backup system). • The overall energy efficiency of the salt plant with TES and FBS is the highest. • The overall exergy efficiency of the oil plant with TES and FBS is the highest. • The salt plants are the best configurations in terms of environ–eco parameters

Application of digital control techniques for satellite medium power DC-DC converters

Science.gov (United States)

Skup, Konrad R.; Grudzinski, Pawel; Nowosielski, Witold; Orleanski, Piotr; Wawrzaszek, Roman

2010-09-01

The objective of this paper is to present a work concerning a digital control loop system for satellite medium power DC-DC converters that is done in Space Research Centre. The whole control process of a described power converter bases on a high speed digital signal processing. The paper presents a development of a FPGA digital controller for voltage mode stabilization that was implemented using VHDL. The described controllers are a classical digital PID controller and a bang-bang controller. The used converter for testing is a simple model of 5-20 W, 200 kHz buck power converter. A high resolution digital PWM approach is presented. Additionally a simple and effective solution of filtering of an analog-to-digital converter output is presented.

Interim Service ISDN Satellite (ISIS) simulator development for advanced satellite designs and experiments

Science.gov (United States)

Pepin, Gerard R.

1992-01-01

The simulation development associated with the network models of both the Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures is documented. The ISIS Network Model design represents satellite systems like the Advanced Communications Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) Program, moves all control and switching functions on-board the next generation ISDN communications satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete event simulation experiments will be performed with these models using various traffic scenarios, design parameters, and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

Categorizing natural disaster damage assessment using satellite-based geospatial techniques

Science.gov (United States)

Myint, S.W.; Yuan, M.; Cerveny, R.S.; Giri, C.

2008-01-01

Remote sensing of a natural disaster's damage offers an exciting backup and/or alternative to traditional means of on-site damage assessment. Although necessary for complete assessment of damage areas, ground-based damage surveys conducted in the aftermath of natural hazard passage can sometimes be potentially complicated due to on-site difficulties (e.g., interaction with various authorities and emergency services) and hazards (e.g., downed power lines, gas lines, etc.), the need for rapid mobilization (particularly for remote locations), and the increasing cost of rapid physical transportation of manpower and equipment. Satellite image analysis, because of its global ubiquity, its ability for repeated independent analysis, and, as we demonstrate here, its ability to verify on-site damage assessment provides an interesting new perspective and investigative aide to researchers. Using one of the strongest tornado events in US history, the 3 May 1999 Oklahoma City Tornado, as a case example, we digitized the tornado damage path and co-registered the damage path using pre- and post-Landsat Thematic Mapper image data to perform a damage assessment. We employed several geospatial approaches, specifically the Getis index, Geary's C, and two lacunarity approaches to categorize damage characteristics according to the original Fujita tornado damage scale (F-scale). Our results indicate strong relationships between spatial indices computed within a local window and tornado F-scale damage categories identified through the ground survey. Consequently, linear regression models, even incorporating just a single band, appear effective in identifying F-scale damage categories using satellite imagery. This study demonstrates that satellite-based geospatial techniques can effectively add spatial perspectives to natural disaster damages, and in particular for this case study, tornado damages.

Satellite recovery - Attitude dynamics of the targets

Science.gov (United States)

Cochran, J. E., Jr.; Lahr, B. S.

1986-01-01

The problems of categorizing and modeling the attitude dynamics of uncontrolled artificial earth satellites which may be targets in recovery attempts are addressed. Methods of classification presented are based on satellite rotational kinetic energy, rotational angular momentum and orbit and on the type of control present prior to the benign failure of the control system. The use of approximate analytical solutions and 'exact' numerical solutions to the equations governing satellite attitude motions to predict uncontrolled attitude motion is considered. Analytical and numerical results are presented for the evolution of satellite attitude motions after active control termination.

Emergency contraceptive pills as a backup for lactational amenorrhea method (LAM) of contraception: a randomized controlled trial.

Science.gov (United States)

Shaaban, Omar M; Hassen, Shaimaa G; Nour, Sanna A; Kames, Mervat A; Yones, Entsar M

2013-03-01

The use of breastfeeding as a method of birth spacing occasionally ends in "unplanned pregnancy." This is due to unexpected expiration of one or more of the lactation amenorrhea method (LAM) prerequisites. The current study tests a new concept that the in-advance provision of single packet of progestogen emergency contraception (EC) pills during the postpartum LAM counseling may decrease the incidence of unplanned pregnancy during breastfeeding. This was a registered two-armed randomized controlled trial (NCT 01111929). Women intending to breastfeed and to postpone pregnancy for 1 year or more were approached. They received adequate postpartum contraceptive counseling. Women intending to use LAM were randomly assigned to one of two groups. The LAM-only group received the proper LAM counseling and did not receive counseling about EC. The LAM-EC group received counseling for both LAM and EC with in-advance provision of one packet of EC pills. They were advised to use these pills if one of the prerequisites of LAM expires and sexual relation has occurred before the initiation of another regular contraceptive protection. All the participants were advised that they need to use another regular method upon expiration of any of the LAM prerequisites. Eligible women were 1158 parturients randomized into two equal groups. Forty-four percent of the women provided with EC used them. Significantly more women in the LAM-EC group initiated regular contraception within or shortly after the first 6 months postpartum when compared with those in the LAM-only group (30.5% vs. 7.3%, respectively; p=.0004). Pregnancy occurred in 5% of the LAM-only group as compared with 0.8% in the LAM-EC group (p=.005). Minimal side effects were reported after EC use. In-advance provision of EC pills can increase the rate of initiation of regular contraception once one or more of the prerequisites of LAM expire. Consequently, the use of EC pills as a temporary backup of LAM can decrease the incidence

Supply of clean water to the bearings and mechanical seals of the backup pumps

International Nuclear Information System (INIS)

Jolas, C.

1997-01-01

The purpose of the backup pumps is to cool the primary circuit and pressurised water reactor containment in the case of a primary cooler loss accident. The water taken in by these pumps in the case of accident is loaded with solid particles. In order to ensure correct operation of the bearings and mechanical seals of these machines, they must be supplied with clean water. In other words, the solid particles must be removed from the water intake. Manufacturers generally use cyclonic separators to achieve this. (author)

Joint Polar Satellite System (JPSS) Common Ground System (CGS) Overview and Architectural Tenets

Science.gov (United States)

Miller, S. W.; Grant, K. D.; Jamilkowski, M. L.

2013-12-01

The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence and Information Systems (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS provides a wide range of support to a number of missions: 1) Command and control and mission management for the Suomi National Polar Partnership (S-NPP) mission today, expanding this support to the JPSS-1 satellite and the Polar Free Flyer mission in 2017 2) Data acquisition via a Polar Receptor Network (PRN) for S-NPP, the Japan Aerospace Exploration Agency's (JAXA) Global Change Observation Mission - Water (GCOM-W1), POES, and the Defense Meteorological Satellite Program (DMSP) and Coriolis/WindSat for the Department of Defense (DoD) 3) Data routing over a global fiber Wide Area Network (WAN) for S-NPP, JPSS-1, Polar Free Flyer, GCOM-W1, POES, DMSP, Coriolis/WindSat, the NASA Space Communications and Navigation (SCaN, which includes several Earth Observing System [EOS] missions), MetOp for the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the National Science Foundation (NSF) 4) Environmental data processing and distribution for S-NPP, GCOM-W1 and JPSS-1 The CGS architecture will receive a technology refresh in 2015 to satisfy several key

Design of tracking mount and controller for mobile satellite laser ranging system

Science.gov (United States)

Park, Cheol Hoon; Son, Young Su; Kim, Byung In; Ham, Sang Young; Lee, Sung Whee; Lim, Hyung Chul

2012-01-01

In this study, we have proposed and implemented a design for the tracking mount and controller of the ARGO-M (Accurate Ranging system for Geodetic Observation - Mobile) which is a mobile satellite laser ranging (SLR) system developed by the Korea Astronomy and Space Science Institute (KASI) and Korea Institute of Machinery and Materials (KIMM). The tracking mount comprises a few core components such as bearings, driving motors and encoders. These components were selected as per the technical specifications for the tracking mount of the ARGO-M. A three-dimensional model of the tracking mount was designed. The frequency analysis of the model predicted that the first natural frequency of the designed tracking mount was high enough. The tracking controller is simulated using MATLAB/xPC Target to achieve the required pointing and tracking accuracy. In order to evaluate the system repeatability and tracking accuracy of the tracking mount, a prototype of the ARGO-M was fabricated, and repeatability tests were carried out using a laser interferometer. Tracking tests were conducted using the trajectories of low earth orbit (LEO) and high earth orbit (HEO) satellites. Based on the test results, it was confirmed that the prototype of the tracking mount and controller of the ARGO-M could achieve the required repeatability along with a tracking accuracy of less than 1 arcsec.

Degradation Effect on Reliability Evaluation of Aluminum Electrolytic Capacitor in Backup Power Converter

DEFF Research Database (Denmark)

Zhou, Dao; Wang, Huai; Blaabjerg, Frede

2017-01-01

DC capacitors in power electronic converters are a major constraint on improvement of power density as well as reliability. In this paper, according to the degradation data of electrolytic capacitors through the accelerated test, the time-to-failure of the capacitor cell is acquired and it can...... be further extended to lower stress levels. Then, in a case study of a fuel cell backup power application, the mission profile based lifetime expectancy of the individual capacitor and the capacitor bank is estimated in terms of the standby mode and operation mode. The lifetime prediction of the capacitor...

Power supply for control and instrumentation in Fast Breeder Test Reactor

International Nuclear Information System (INIS)

Raghavan, K.; Shanmugam, T.K.

1977-01-01

The design and operation of the four 'no-break' power supplies for control and instrumentation in the Fast Breeder Test Reactor (FBTR), Kalpakkam, are described. Interruptions in the power supplies are eliminated by redundancy and battery back-up source while voltage dips and transients are taken care by automatic regulation system. The four power supplies are : (1) 24 V D.C. exclusively for neutronic and safety circuits, (2) 48 V D.C. for control logic indication lamps and solenoid valves, (3) 220 V D.C. for switchgear control, control room emergency lighting and D.C. flushing oil pump for the turbine and (4) 220 V A.C. single-phase 50 H/Z for computers and electronics of control and instrumentation. Stationary lead-acid batteries (lead antimony type) in floating mode operation with rectifier/charger are used for emergency back-up. All these power supplies are fed by 415 V, 3-phase, 50 HZ emergency supply buses which are provided with diesel generator back-up. Static energy conversion system (in preference to mechanical rotation system) is used for A.C. to D.C. and also for A.C. to A.C. conversion. (M.G.B.)

ERROR-CONTROL CODING OF ADS-B MESSAGES FOR IRIDIUM SATELLITES

Directory of Open Access Journals (Sweden)

Volodymyr Kharchenko

2013-12-01

Full Text Available For modelling of ADS-B messages transmitting on the base of low-orbit satellite constellation Іrіdіum the model of a communication channel “Aircraft - Satellite - Ground Station” was built using MATLAB Sіmulіnk. This model allowed to investigate dependences of the Bit Error Rate on a type of  signal coding/decoding, ratio Eb/N0 and satellite repeater gain

A Distributed Flight Software Design for Satellite Formation Flying Control

National Research Council Canada - National Science Library

Mueller, Joseph B; Brito, Margarita

2003-01-01

.... Princeton Satellite Systems developed the Formation Flying Module (FFM) for TechSat 21 to provide autonomous reconfiguration, formation keeping,and collision avoidance capabilities to the three-satellite cluster...

STS-65 crewmembers and backup participate in bench review at Boeing Building

Science.gov (United States)

1994-01-01

STS-65 crewmembers, wearing clean suits, look over equipment to be carried aboard the Space Shuttle Columbia, Orbiter Vehicle (OV) 102, for the scheduled July flight of the second International Microgravity Laboratory (IML-2) mission. Surrounding a table full of equipment at Boeing's Flight Equipment Processing Facility near the Johnson Space Center (JSC), are (left to right) Mission Specialist (MS) Leroy Chiao, MS Donald A. Thomas, Commander Robert D. Cabana, Payload Specialist Chiaki Mukai, Payload Commander (PLC) Richard J. Hieb, and backup (alternate) payload specialist Jean-Jacques Favier. Mukai represents Japan's National Space Development Agency (NASDA) and Favier represents France's Centre National d'Etudes Spatiales. Photo taken by NASA JSC contract photographer Scott A. Wickes.

A satellite digital controller or 'play that PID tune again, Sam'. [Position, Integral, Derivative feedback control algorithm for design strategy

Science.gov (United States)

Seltzer, S. M.

1976-01-01

The problem discussed is to design a digital controller for a typical satellite. The controlled plant is considered to be a rigid body acting in a plane. The controller is assumed to be a digital computer which, when combined with the proposed control algorithm, can be represented as a sampled-data system. The objective is to present a design strategy and technique for selecting numerical values for the control gains (assuming position, integral, and derivative feedback) and the sample rate. The technique is based on the parameter plane method and requires that the system be amenable to z-transform analysis.

Security Concepts for Satellite Links

Science.gov (United States)

Tobehn, C.; Penné, B.; Rathje, R.; Weigl, A.; Gorecki, Ch.; Michalik, H.

2008-08-01

The high costs to develop, launch and maintain a satellite network makes protecting the assets imperative. Attacks may be passive such as eavesdropping on the payload data. More serious threat are active attacks that try to gain control of the satellite, which may lead to the total lost of the satellite asset. To counter these threats, new satellite and ground systems are using cryptographic technologies to provide a range of services: confidentiality, entity & message authentication, and data integrity. Additionally, key management cryptographic services are required to support these services. This paper describes the key points of current satellite control and operations, that are authentication of the access to the satellite TMTC link and encryption of security relevant TM/TC data. For payload data management the key points are multi-user ground station access and high data rates both requiring frequent updates and uploads of keys with the corresponding key management methods. For secure satellite management authentication & key negotiation algorithms as HMAC-RIPEMD160, EC- DSA and EC-DH are used. Encryption of data uses algorithms as IDEA, AES, Triple-DES, or other. A channel coding and encryption unit for payload data provides download data rates up to Nx250 Mbps. The presented concepts are based on our experience and heritage of the security systems for all German MOD satellite projects (SATCOMBw2, SAR-Lupe multi- satellite system and German-French SAR-Lupe-Helios- II systems inter-operability) as well as for further international (KOMPSAT-II Payload data link system) and ESA activities (TMTC security and GMES).

Fuzzy Logic Controller for Small Satellites Navigation

National Research Council Canada - National Science Library

Della Pietra, G; Falzini, S; Colzi, E; Crisconio, M

2005-01-01

.... The navigator aims at operating satellites in orbit with a minimum ground support and very good performances, by the adoption of innovative technologies, such as attitude observation GPS, attitude...

Attitude and vibration control of a satellite containing flexible solar arrays by using reaction wheels, and piezoelectric transducers as sensors and actuators

Science.gov (United States)

da Fonseca, Ijar M.; Rade, Domingos A.; Goes, Luiz C. S.; de Paula Sales, Thiago

2017-10-01

The primary purpose of this paper is to provide insight into control-structure interaction for satellites comprising flexible appendages and internal moving components. The physical model considered herein aiming to attend such purpose is a rigid-flexible satellite consisting of a rigid platform containing two rotating flexible solar panels. The solar panels rotation is assumed to be in a sun-synchronous configuration mode. The panels contain surface-bonded piezoelectric patches that can be used either as sensors for the elastic displacements or as actuators to counteract the vibration motion. It is assumed that in the normal mode operation the satellite platform points towards the Earth while the solar arrays rotate so as to follow the Sun. The vehicle moves in a low Earth polar orbit. The technique used to obtain the mathematical model combines the Lagrangian formulation with the Finite Elements Method used to describe the dynamics of the solar panel. The gravity-gradient torque as well as the torque due to the interaction of the Earth magnetic field and the satellite internal residual magnetic moment is included as environmental perturbations. The actuators are three reaction wheels for attitude control and piezoelectric actuators to control the flexible motion of the solar arrays. Computer simulations are performed using the MATLAB® software package. The following on-orbit satellite operating configurations are object of analysis: i) Satellite pointing towards the Earth (Earth acquisition maneuver) by considering the initial conditions in the elastic displacement equal to zero, aiming the assessment of the flexible modes excitation by the referred maneuver; ii) the satellite pointing towards the Earth with the assumption of an initial condition different from zero for the flexible motion such that the attitude alterations are checked against the elastic motion disturbance; and iii) attitude acquisition accomplished by taking into account initial conditions

Hardware design of a microcomputer controlled diagnostic vacuum controller

International Nuclear Information System (INIS)

Marsala, R.J.

1983-01-01

The TFTR diagnostic vacuum controller (DVC) has been designed and built to control and monitor the pumps, valves and gauges which comprise a diagnostic vacuum system. The DVC is a microcomputer based self-contained controller with battery backup which may be controlled manually from front panel controls or remotely via CICADA. The DVC implements all pump and valve sequencing and provides protection against incorrect operation. There are presently two versions of the DVC operating on TFTR and a third version being used on the S-1 machine

The use of different analytical techniques as a backup to mineral resources assessment

International Nuclear Information System (INIS)

Carvalho Tofani, P. de; Ferreira, M.P.; Gomes, H.; Avelar, M.M.

1982-01-01

The Empresas Nucleares Brasileiras S.A. (NUCLEBRAS) has implemented and improved, since their foundation in 1974, several laboratories at the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), in Belo Horizonte (MG, Brazil), in order to develop capabilities in the analytical chemistry field. Skillful personnel, using a large spectrum of equipment and procedures, is already able to determine, fast and accurately, almost any chemical element in any matrix. About 340.000 analytical determinations have been performed during the last seven years, concerning mostly chemical elements of great importance in the mineral technology programs. This considerable amount of results has been used, specially, as a backup to assess Brazilian uranium resources. (Author) [pt

Design of an Adaptive-Neural Network Attitude Controller of a Satellite using Reaction Wheels

Directory of Open Access Journals (Sweden)

Abbas Ajorkar

2015-04-01

Full Text Available In this paper, an adaptive attitude control algorithm is developed based on neural network for a satellite using four reaction wheels in a tetrahedron configuration. Then, an attitude control based on feedback linearization control has been designed and uncertainties in the moment of inertia matrix and disturbances torque have been considered. In order to eliminate the effect of these uncertainties, a multilayer neural network with back-propagation law is designed. In this structure, the parameters of the moment of inertia matrix and external disturbances are estimated and used in feedback linearization control law. Finally, the performance of the designed attitude controller is investigated by several simulations.

IAEA ICSP on HWR moderator subcooling requirements to demonstrate backup heat sink

International Nuclear Information System (INIS)

Choi, J.; Nitheanandan, T.

2013-01-01

The IAEA launched a new International Collaborative Standard Problem (ICSP) on 'HWR Moderator Subcooling Requirements to Demonstrate Backup Heat Sink Capabilities of Moderator during Accidents'. The purpose of the ICSP is to benchmark analysis computer codes in simulating contact boiling experimental data to assess the subcooling requirements for an overheated pressure tube, plastically deforming into contact with the calandria tube during a postulated large break loss of coolant accident. The experimental data obtained for the ICSP blind simulation can be used to assess safety analysis computer codes simulating thermal radiation heat transfer to the pressure tube, pressure tube deformation or failure, pressure tube to calandria tube heat transfer, calandria tube to moderator heat transfer, and calandria tube deformation or failure. (author)

MARTe at FTU: The new feedback control

Energy Technology Data Exchange (ETDEWEB)

Boncagni, Luca, E-mail: luca.boncagni@enea.it [EURATOM - ENEA Fusion Association, Frascati Research Centre, Division of Fusion Physics, Rome, Frascati (Italy); Sadeghi, Yahya; Carnevale, Daniele; Di Geronimo, Andrea; Varano, Gianluca; Vitelli, Riccardo [Department of Computer Science, Systems and Production, University of Rome Tor Vergata, Rome (Italy); Galperti, Critsian [Istituto di Fisica del Plasma, CNR, EURATOM-ENEA Association, Milan (Italy); Zarfati, Emanuele; Pucci, Daniele [Department Antonio Ruberti, University of Rome La Sapienza, Rome (Italy)

2012-12-15

Highlights: Black-Right-Pointing-Pointer We show that the MARTe is a candidate for ITER PSH. Black-Right-Pointing-Pointer We replace the old real-time feedback software using the MARTe framework. Black-Right-Pointing-Pointer We describe all the work done for the integration. - Abstract: Keeping in mind the necessities of a modern control system for fusion devices, such as modularity and a distributed architecture, an upgrade of the present FTU feedback control system was planned, envisaging also a possible reutilization in the proposed FAST experiment [1]. For standardization and efficiency purposes we decided to adopt a pre-existent ITER-relevant framework called MARTe [2], already used with success in other European Tokamak devices [3]. Following the developments shown in [4], in this paper we report on the structure of the new feedback system, and how it was integrated in the current control structure and pulse programming interface, and in the other MARTe systems already in FTU: RT-ODIN [5] and the ECRH and LH [6] satellite stations. The new feedback system has been installed in the FTU backup station (known as 'Feedback B'), which shares the input signals with the actual feedback system, in order to simplify the validation and debug of the new controller by testing it in parallel with the current one. Experimental results are then presented.

Characteristics of a lithium-thionyl chloride battery as a memory back-up power source

Science.gov (United States)

Iwamaru, T.; Uetani, Y.

An Li/SOCl 2 battery of R6 size (ER6C) has been evaluated as a memory back-up power source for CMOS RAM. The working voltage is 3.6 V and the discharge capacity is 1900 mA h on a 1OK-ohm load. The cell exhibits satisfactory working voltage and discharge capacity over the temperature range -40 °C to 85 °C. The discharge reaction mechanism has been elucidated. Cumulative self discharge during 10 years discharge at 20 μA is estimated to be 3.5%. No serious problems have been observed during abuse tests.

Characteristics of a lithium-thionyl chloride battery as a memory back-up power source

Energy Technology Data Exchange (ETDEWEB)

Iwamaru, T.; Uetani, Y.

1987-05-01

An Li/SOCl/sub 2/ battery of R6 size (ER6C) has been evaluated as a memory back-up power source for CMOS RAM. The working voltage is 3.6 V and the discharge capacity is 1900 mA h on a 10K-ohm load. The cell exhibits satisfactory working voltage and discharge capacity over the temperature range -40/sup 0/C to 85/sup 0/C. The discharge reaction mechanism has been elucidated. Cumulative self discharge during 10 years discharge at 20 ..mu..A is estimated to be 3.5%. No serious problems have been observed during abuse tests.

IMPLEMENTATION OF AERONAUTICAL LOCAL SATELLITE AUGMENTATION SYSTEM

Directory of Open Access Journals (Sweden)

Stojce Ilcev

2011-03-01

Full Text Available Abstract. This paper introduces development and implementation of new Local Satellite AugmentationSystem as an integration component of the Regional Satellite Augmentation System (RSAS employingcurrent and new Satellite Communications, Navigation and Surveillance (CNS for improvement of the AirTraffic Control (ATC and Air Traffic Management (ATM and for enhancement safety systems includingtransport security and control of flights in all stages, airport approaching, landing, departures and allmovements over airport surface areas. The current first generation of the Global Navigation Satellite SystemGNSS-1 applications are represented by fundamental military solutions for Position, Velocity and Time ofthe satellite navigation and determination systems such as the US GPS and Russian GLONASS (Former-USSR requirements, respectively. The establishment of Aeronautical CNS is also discussed as a part ofGlobal Satellite Augmentation Systems of GPS and GLONASS systems integrated with existing and futureRSAS and LSAS in airports areas. Specific influence and factors related to the Comparison of the Currentand New Aeronautical CNS System including the Integration of RSAS and GNSS solutions are discussedand packet of facts is determined to maximize the new satellite Automatic Dependent Surveillance System(ADSS and Special Effects of the RSAS Networks. The possible future integration of RSAS and GNSS andthe common proposal of the satellite Surface Movement Guidance and Control are presented in thechangeless ways as of importance for future enfacements of ATC and ATM for any hypothetical airportinfrastructure.Keywords: ADSS, ATC, ATM, CNS, GSAS, LRAS, RSAS, SMGC, Special Effects of RSAS.

Flight results from the gravity-gradient-controlled RAE-1 satellite

Science.gov (United States)

Blanchard, D. L.

1986-01-01

The in-orbit dynamics of a large, flexible spacecraft has been modeled with a computer simulation, which was used for designing the control system, developing a deployment and gravity-gradient capture procedure, predicting the steady-state behavior, and designing a series of dynamics experiments for the Radio Astronomy Explorer (RAE) satellite. This flexible body dynamics simulator permits three-dimensional, large-angle rotation of the total spacecraft and includes effects of orbit eccentricity, thermal bending, solar pressure, gravitational accelerations, and the damper system. Flight results are consistent with the simulator predictions and are presented for the deployment and capture phases, the steady-state mission, and the dynamics experiments.

Adaptive FTC based on Control Allocation and Fault Accommodation for Satellite Reaction Wheels

DEFF Research Database (Denmark)

Baldi, P.; Blanke, Mogens; Castaldi, P.

2016-01-01

and fault accommodation module directly exploiting the on-line fault estimates. The use of the nonlinear geometric approach and radial basis function neural networks allows to obtain a precise fault isolation, independently from the knowledge of aerodynamic disturbance parameters, and to design generalised......This paper proposes an active fault tolerant control scheme to cope with faults or failures affecting the flywheel spin rate sensors or satellite reaction wheel motors. The active fault tolerant control system consists of a fault detection and diagnosis module along with a control allocation...... estimation filters, which do not need a priori information about the internal model of the signal to be estimated. The adaptive control allocation and sensor fault accommodation can handle both temporal faults and failures. Simulation results illustrate the convincing fault correction and attitude control...

Satellites

International Nuclear Information System (INIS)

Burns, J.A.; Matthews, M.S.

1986-01-01

The present work is based on a conference: Natural Satellites, Colloquium 77 of the IAU, held at Cornell University from July 5 to 9, 1983. Attention is given to the background and origins of satellites, protosatellite swarms, the tectonics of icy satellites, the physical characteristics of satellite surfaces, and the interactions of planetary magnetospheres with icy satellite surfaces. Other topics include the surface composition of natural satellites, the cratering of planetary satellites, the moon, Io, and Europa. Consideration is also given to Ganymede and Callisto, the satellites of Saturn, small satellites, satellites of Uranus and Neptune, and the Pluto-Charon system

RPAS ADS-B AND TRAJECTORY CONTROL DATA TRANSMISSION VIA SATELLITE

Directory of Open Access Journals (Sweden)

Andrii Grekhov

2017-11-01

Full Text Available Purpose: to develop a model of the satellite communication channel for an remotely piloted air system with adaptive modulation and orthogonal frequency division of channels; 2 to calculate the channel parameters with Rayleigh fading and various types of satellite transponder nonlinearity; 3 analyze the effect of fading and the type of nonlinearity on the parameters of the satellite communication channel. Method: MATLAB Simulink software was used to simulate the channel operation. Results: For the first time, based on the IEEE 802.16d standard, a realistic model of the satellite communication channel of an unmanned aerial vehicle was developed, which is used to estimate the channel parameters. The created model takes into account the Rayleigh fading in the downlink and the nonlinearity of the satellite transponder amplifier. Dependences of the signal-to-noise ratio in the terrestrial receiver on the signal-to-noise ratio in the downlink for various types of modulation (BPSK, QPSK, 16QAM, 64QAM and data transmission rates are obtained. The nonlinearity of satellite amplifiers was analyzed on the basis of a linear model, a cubic polynomial model, a hyperbolic tangential model, the Gorbani model, and the Rapp model. The results for the cubic polynomial model and the hyperbolic tangential model are similar to the linear model, but differ significantly from the Gorbani model and the Rapp model. For the Gorbani and Rapp models, very low values of the signal-to-noise ratio in the receiver are observed. Conclusion: The proposed approach can be considered as a method of estimating the parameters of the satellite communication channel of an unmanned aerial vehicle with fading. It is shown how the type of modulation varies depending on the level of the signal-to-noise ratio and the type of fading. The developed model allows to predict the operation of the channel with Rayleigh fading and can be useful for the design of communication systems.

Fault tolerancy in cooperative adaptive cruise control

NARCIS (Netherlands)

Nunen, E. van; Ploeg, J.; Medina, A.M.; Nijmeijer, H.

2013-01-01

Future mobility requires sound solutions in the field of fault tolerance in real-time applications amongst which Cooperative Adaptive Cruise Control (CACC). This control system cannot rely on the driver as a backup and is constantly active and therefore more prominent to the occurrences of faults

Spectrum and power allocation in cognitive multi-beam satellite communications with flexible satellite payloads

Science.gov (United States)

Liu, Zhihui; Wang, Haitao; Dong, Tao; Yin, Jie; Zhang, Tingting; Guo, Hui; Li, Dequan

2018-02-01

In this paper, the cognitive multi-beam satellite system, i.e., two satellite networks coexist through underlay spectrum sharing, is studied, and the power and spectrum allocation method is employed for interference control and throughput maximization. Specifically, the multi-beam satellite with flexible payload reuses the authorized spectrum of the primary satellite, adjusting its transmission band as well as power for each beam to limit its interference on the primary satellite below the prescribed threshold and maximize its own achievable rate. This power and spectrum allocation problem is formulated as a mixed nonconvex programming. For effective solving, we first introduce the concept of signal to leakage plus noise ratio (SLNR) to decouple multiple transmit power variables in the both objective and constraint, and then propose a heuristic algorithm to assign spectrum sub-bands. After that, a stepwise plus slice-wise algorithm is proposed to implement the discrete power allocation. Finally, simulation results show that adopting cognitive technology can improve spectrum efficiency of the satellite communication.

Launching the First Indian Satellite

Indian Academy of Sciences (India)

materials and chemicals, rocket propulsion, satellite technology, control and guidance system, etc. ... entire country, especially the rural areas, and in the survey and management of natural resources. Listeners are no .... satellite will store the information over a longer period and then on command from the ground station at ...

Advanced satellite servicing facility studies

Science.gov (United States)

Qualls, Garry D.; Ferebee, Melvin J., Jr.

1988-01-01

A NASA-sponsored systems analysis designed to identify and recommend advanced subsystems and technologies specifically for a manned Sun-synchronous platform for satellite management is discussed. An overview of system design, manned and unmanned servicing facilities, and representative mission scenarios are given. Mission areas discussed include facility based satellite assembly, checkout, deployment, refueling, repair, and systems upgrade. The ferrying of materials and consumables to and from manufacturing platforms, deorbit, removal, repositioning, or salvage of satellites and debris, and crew rescue of any other manned vehicles are also examined. Impacted subsytems discussed include guidance navigation and control, propulsion, data management, power, thermal control, structures, life support, and radiation management. In addition, technology issues which would have significant impacts on the system design are discussed.

Optimized Heat Pipe Backup Cooling System Tested with a Stirling Convertor

Science.gov (United States)

Schwendeman, Carl L.; Tarau, Calin; Schifer, Nicholas A.; Anderson, William G.; Garner, Scott

2016-01-01

In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal variable conductance heat pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor by bypassing the heat during stops. In a previous NASA Small Business Innovation Research (SBIR) Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for the Stirling RPS. In 2012, one of these VCHPs was successfully tested at NASA Glenn Research Center with a Stirling convertor as an Advanced Stirling Radioisotope Generator (ASRG) backup cooling system. The prototype; however, was not optimized and did not reflect the final heat rejection path. ACT through further funding has developed a semioptimized prototype with the finalized heat path for testing at Glenn with a Stirling convertor. The semioptimized system features a two-phase radiator and is significantly smaller and lighter than the prior prototype to reflect a higher level of flight readiness. The VCHP is designed to activate and remove heat from the GPHS during stoppage with a small temperature increase from the nominal vapor temperature. This small temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the multilayer insulation (MLI). The VCHP passively allows the Stirling convertor to be turned off multiple times during a mission with potentially unlimited off durations. Having the ability to turn the Stirling off allows for the Stirling to be reset and reduces vibrations on the platform during sensitive measurements or

DS-CDMA satellite diversity reception for personal satellite communication: Downlink performance analysis

Science.gov (United States)

DeGaudenzi, Riccardo; Giannetti, Filippo

1995-01-01

The downlink of a satellite-mobile personal communication system employing power-controlled Direct Sequence Code Division Multiple Access (DS-CDMA) and exploiting satellite-diversity is analyzed and its performance compared with a more traditional communication system utilizing single satellite reception. The analytical model developed has been thoroughly validated by means of extensive Monte Carlo computer simulations. It is shown how the capacity gain provided by diversity reception shrinks considerably in the presence of increasing traffic or in the case of light shadowing conditions. Moreover, the quantitative results tend to indicate that to combat system capacity reduction due to intra-system interference, no more than two satellites shall be active over the same region. To achieve higher system capacity, differently from terrestrial cellular systems, Multi-User Detection (MUD) techniques are likely to be required in the mobile user terminal, thus considerably increasing its complexity.

SDI satellite autonomy using AI and Ada

Science.gov (United States)

Fiala, Harvey E.

1990-01-01

The use of Artificial Intelligence (AI) and the programming language Ada to help a satellite recover from selected failures that could lead to mission failure are described. An unmanned satellite will have a separate AI subsystem running in parallel with the normal satellite subsystems. A satellite monitoring subsystem (SMS), under the control of a blackboard system, will continuously monitor selected satellite subsystems to become alert to any actual or potential problems. In the case of loss of communications with the earth or the home base, the satellite will go into a survival mode to reestablish communications with the earth. The use of an AI subsystem in this manner would have avoided the tragic loss of the two recent Soviet probes that were sent to investigate the planet Mars and its moons. The blackboard system works in conjunction with an SMS and a reconfiguration control subsystem (RCS). It can be shown to be an effective way for one central control subsystem to monitor and coordinate the activities and loads of many interacting subsystems that may or may not contain redundant and/or fault-tolerant elements. The blackboard system will be coded in Ada using tools such as the ABLE development system and the Ada Production system.

Handbook of satellite applications

CERN Document Server

Madry, Scott; Camacho-Lara, Sergio

2013-01-01

Top space experts from around the world have collaborated to produce this comprehensive, authoritative, and clearly illustrated reference guide to the fast growing, multi-billion dollar field of satellite applications and space communications. This handbook, done under the auspices of the International Space University based in France, addresses not only system technologies but also examines market dynamics, technical standards and regulatory constraints. The handbook is a completely multi-disciplinary reference book that covers, in an in-depth fashion, the fields of satellite telecommunications, Earth observation, remote sensing, satellite navigation, geographical information systems, and geosynchronous meteorological systems. It covers current practices and designs as well as advanced concepts and future systems. It provides a comparative analysis of the common technologies and design elements for satellite application bus structures, thermal controls, power systems, stabilization techniques, telemetry, com...

Guidance, Navigation, and Control System for Maneuverable Pico-Satellites, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A compact, low-power GN&C system is essential to the success of pico-satellite Automated Rendezvous and Docking (AR&D). Austin Satellite Design (ASD)...

Is modification of the VVI backup mode in implantable cardioverter-defibrillators from St Jude medical required due to increased risk of inappropriate shocks?

DEFF Research Database (Denmark)

Philbert, Berit Thornvig; Tfelt-Hansen, Jacob; Jacobsen, Peter K

2017-01-01

Inappropriate implantable cardioverter-defibrillator (ICD) shock therapy is painful, stressful, and typically occurs unexpected in conscious patients and may be related to a less favourable prognosis. In our institution, we have observed four cases of multiple inappropriate ICD shocks during reset...... a ventricular fibrillation (VF) zone starting at 146 b.p.m., with shock therapy only and changes in sensitivity settings making the ICD more sensitive. In all cases, the reason for the multiple inappropriate shocks was that the VF zone was reached due to exercise-induced sinus tachycardia or due to oversensing...... during sinus rhythm. The VVI backup mode has to balance between protection from failure of ICD therapy during life-threatening ventricular arrhythmias and from inappropriate shocks. It seems the non-programmable parameters in VVI backup mode of St Jude Medical ICDs carry an unacceptable high risk...

Compressed-air and backup nitrogen systems in nuclear power plants

International Nuclear Information System (INIS)

Hagen, E.W.

1982-07-01

This report reviews and evaluates the performance of the compressed-air and pressurized-nitrogen gas systems in commercial nuclear power units. The information was collected from readily available operating experiences, licensee event reports, system designs in safety analysis reports, and regulatory documents. The results are collated and analyzed for significance and impact on power plant safety performance. Under certain circumstances, the fail-safe philosophy for a piece of equipment or subsystem of the compressed-air systems initiated a series of actions culminating in reactor transient or unit scram. However, based on this study of prevailing operating experiences, reclassifying the compressed-gas systems to a higher safety level will neither prevent (nor mitigate) the reoccurrences of such happenings nor alleviate nuclear power plant problems caused by inadequate maintenance, operating procedures, and/or practices. Conversely, because most of the problems were derived from the sources listed previously, upgrading of both maintenance and operating procedures will not only result in substantial improvement in the performance and availability of the compressed-air (and backup nitrogen) systems but in improved overall plant performance

Domestic Communication Satellites

Science.gov (United States)

Horowitz, Andrew

1974-01-01

A discussion of the Federal Communications Commission's new policy on domestic satellites in light of our 1) military and economic history; 2) corporate interests; 3) citizen surveillance; and 4) media control. (HB)

Robust Fault-Tolerant Control for Satellite Attitude Stabilization Based on Active Disturbance Rejection Approach with Artificial Bee Colony Algorithm

Directory of Open Access Journals (Sweden)

Fei Song

2014-01-01

Full Text Available This paper proposed a robust fault-tolerant control algorithm for satellite stabilization based on active disturbance rejection approach with artificial bee colony algorithm. The actuating mechanism of attitude control system consists of three working reaction flywheels and one spare reaction flywheel. The speed measurement of reaction flywheel is adopted for fault detection. If any reaction flywheel fault is detected, the corresponding fault flywheel is isolated and the spare reaction flywheel is activated to counteract the fault effect and ensure that the satellite is working safely and reliably. The active disturbance rejection approach is employed to design the controller, which handles input information with tracking differentiator, estimates system uncertainties with extended state observer, and generates control variables by state feedback and compensation. The designed active disturbance rejection controller is robust to both internal dynamics and external disturbances. The bandwidth parameter of extended state observer is optimized by the artificial bee colony algorithm so as to improve the performance of attitude control system. A series of simulation experiment results demonstrate the performance superiorities of the proposed robust fault-tolerant control algorithm.

An analysis of multiple particle settling for LMR backup shutdown systems

International Nuclear Information System (INIS)

Brock, R.W.

1992-05-01

Backup shutdown systems proposed for future LMRs may employ discreet absorber particles to provide the negative reactivity insertion. When actuated, these systems release a dense packing of particles from an out-of-core region to settle into an in-core region. The multiple particle settling behavior is analyzed by the method of continuity waves. This method provides predictions of the dynamic response of the system including the average particle velocity and volume fraction of particles vs. time. Although hindered settling problems have been previously analyzed using continuity wave theory, this application represents an extension of the theory to conditions of unrestrained settling. Typical cases are analyzed and numerical results are calculated based on a semi-empirical drift-flux model. For 1/4-inch diameter boron-carbide particles in hot liquid sodium, the unrestrained settling problem assumes a steady-state solution when the average volume fraction of particles is 0.295 and the average particle velocity is 26.0 cm/s

Integrated Power and Attitude Control Design of Satellites Based on a Fuzzy Adaptive Disturbance Observer Using Variable-Speed Control Moment Gyros

Directory of Open Access Journals (Sweden)

Zhongyi Chu

2016-01-01

Full Text Available To satisfy the requirements for small satellites that seek agile slewing with peak power, this paper investigates integrated power and attitude control using variable-speed control moment gyros (VSCMGs that consider the mass and inertia of gimbals and wheels. The paper also details the process for developing the controller by considering various environments in which the controller may be implemented. A fuzzy adaptive disturbance observer (FADO is proposed to estimate and compensate for the effects of equivalent disturbances. The algorithms can simultaneously track attitude and power. The simulation results illustrate the effectiveness of the control approach, which exhibits an improvement of 80 percent compared with alternate approaches that do not employ a FADO.

Benefit of adaptive FEC in shared backup path protected elastic optical network.

Science.gov (United States)

Guo, Hong; Dai, Hua; Wang, Chao; Li, Yongcheng; Bose, Sanjay K; Shen, Gangxiang

2015-07-27

We apply an adaptive forward error correction (FEC) allocation strategy to an Elastic Optical Network (EON) operated with shared backup path protection (SBPP). To maximize the protected network capacity that can be carried, an Integer Linear Programing (ILP) model and a spectrum window plane (SWP)-based heuristic algorithm are developed. Simulation results show that the FEC coding overhead required by the adaptive FEC scheme is significantly lower than that needed by a fixed FEC allocation strategy resulting in higher network capacity for the adaptive strategy. The adaptive FEC allocation strategy can also significantly outperform the fixed FEC allocation strategy both in terms of the spare capacity redundancy and the average FEC coding overhead needed per optical channel. The proposed heuristic algorithm is efficient and not only performs closer to the ILP model but also does much better than the shortest-path algorithm.

Toward the Public Dividend: A Report on Satellite Telecommunications and the Public Interest Satellite Association.

Science.gov (United States)

McGraw, Walter

This report points out that the communications satellite appears to be on its way to becoming one of the most dominant and controlling technologies of our time, and this requires that a new evaluation be made of our entire communications process. The first section of the report discusses many aspects of the history of satellites, including the…

Marketing CE approved off-the-shelf FC-operated power backup units for the telecom industry at competitive prices : a continuing success story

Energy Technology Data Exchange (ETDEWEB)

Mortensen, P. [Dantherm Power, Skive (Denmark)

2009-07-01

Dantherm Power receives a steady supply of fuel cell stacks packed on pallets at its factory in Denmark. Once unpacked, they go to an assembly line to be integrated into power modules designed for telecom- and IT network-base-stations around the world. The CE approved units are designed and tested to meet current telecom standards. Customers can purchase the off-the-shelf units at competitive prices. Dantherm Power has brought fuel-cell technology beyond the research and development stage. Since 2005, the company has sold backup units providing uninterruptible power supply (UPS) to the telecom industry on standard commercial terms. Their fuel cell-based-solutions have proven to be successful. The company began in 2003 as a research and development project within Dantherm Air Handling A/S. Development was driven by the idea that a UPS-system based on hydrogen and fuel-cell-technology may be better solution than traditional battery and diesel driven backup for many of the company's existing clients.

Satellite switched FDMA advanced communication technology satellite program

Science.gov (United States)

Atwood, S.; Higton, G. H.; Wood, K.; Kline, A.; Furiga, A.; Rausch, M.; Jan, Y.

1982-01-01

The satellite switched frequency division multiple access system provided a detailed system architecture that supports a point to point communication system for long haul voice, video and data traffic between small Earth terminals at Ka band frequencies at 30/20 GHz. A detailed system design is presented for the space segment, small terminal/trunking segment at network control segment for domestic traffic model A or B, each totaling 3.8 Gb/s of small terminal traffic and 6.2 Gb/s trunk traffic. The small terminal traffic (3.8 Gb/s) is emphasized, for the satellite router portion of the system design, which is a composite of thousands of Earth stations with digital traffic ranging from a single 32 Kb/s CVSD voice channel to thousands of channels containing voice, video and data with a data rate as high as 33 Mb/s. The system design concept presented, effectively optimizes a unique frequency and channelization plan for both traffic models A and B with minimum reorganization of the satellite payload transponder subsystem hardware design. The unique zoning concept allows multiple beam antennas while maximizing multiple carrier frequency reuse. Detailed hardware design estimates for an FDMA router (part of the satellite transponder subsystem) indicate a weight and dc power budget of 353 lbs, 195 watts for traffic model A and 498 lbs, 244 watts for traffic model B.

Advanced Communication Technology Satellite (ACTS) Very Small Aperture Terminal (VSAT) Network Control Performance

Science.gov (United States)

Coney, T. A.

1996-01-01

This paper discusses the performance of the network control function for the Advanced Communications Technology Satellite (ACTS) very small aperture terminal (VSAT) full mesh network. This includes control of all operational activities such as acquisition, synchronization, timing and rain fade compensation as well as control of all communications activities such as on-demand integrated services (voice, video, and date) connects and disconnects Operations control is provided by an in-band orderwire carried in the baseboard processor (BBP) control burst, the orderwire burst, the reference burst, and the uplink traffic burst. Communication services are provided by demand assigned multiple access (DAMA) protocols. The ACTS implementation of DAMA protocols ensures both on-demand and integrated voice, video and data services. Communications services control is also provided by the in-band orderwire but uses only the reference burst and the uplink traffic burst. The performance of the ACTS network control functions have been successfully tested during on-orbit checkout and in various VSAT networks in day to day operations. This paper discusses the network operations and services control performance.

The backup is active in Alzheimer's disease: a hypothesis from problem theory.

Science.gov (United States)

Burnand, Gordon

2015-03-01

Problem theory distinguishes between six general problems of everyday life, which people work through in turn during childhood, learning to switch between them. One of them requires the protection of a cut-out and an override. People who develop Alzheimer's disease (AD), and apolipoprotein allele epsilon 4 carriers, are preoccupied with this problem, or readily switch back to it. It is the freedom problem, of raising hope or confidence of freedom or power to control. Here people try to raise hope of success with any task on which attention happens to rest. This indiscriminateness means that there is no basis for giving up on a task, or for avoiding dangerous environments. Thus the cut-out is needed when someone becomes stuck on a mental task and the override is needed so as to help in avoiding danger. Activity relevant to the freedom problem is confined to the left hemisphere and the right hemisphere operates the cut-out and override. In providing these two forms of protection the right hemisphere can be said to act as a backup. Accordingly EEG, metabolism, and atrophy findings indicate that both cut-out and override are active in mild clinical impairment, especially among patients who later develop AD. The pattern of atrophy of AD matches what would be expected from disuse caused by an overactive cut-out followed by an overactive override. A parallel loss of testosterone might contribute to the weakening of resistance to infections leading to autoimmune effects. Copyright © 2015 The Author. Published by Elsevier Ltd.. All rights reserved.

Beach erosion control study at Pass Christian. [using remote sensors and satellite observation

Science.gov (United States)

1978-01-01

The methods of measuring the existence of erosion and the effects of sand stabilization control systems are described. The mechanics of sand movement, the nature of sand erosion, and the use of satellite data to measure these factors and their surrogates are discussed using the locational and control aspects of aeolian and litoral erosion zones along the sand beach of the Mississippi coast. The aeolian erosion is highlighted due to the redeposition of the sand which causes high cleanup costs, property damage, and safety and health hazards. The areas of differential erosion and the patterns of beach sand movement are illustrated and the use of remote sensing methods to identify the areas of erosion are evaluated.

Study on Utilization of an Artesian Well as a Source of Water Supply at Raw Water Backup System (GBA01)

International Nuclear Information System (INIS)

Santosa Pujiarta; Yuyut Suraniyanto; Amril; Setyo Budi Utomo

2012-01-01

Raw water supply system (GBA01) is a unit of ponds used as a provider of raw water for secondary cooling system and free mineral water production systems. Source of raw water pond has been supplied from PAM Puspiptek with water conductivity between 126-310 μS / cm and a pH of 6 to 8, and this condition is maintained because there is no other source that is used to supply water to the reactor cooling water supply. This conductivity is always unstable, if during the dry season the conductivity is low trend, but in the rainy season the conductivity will be increase because the water contains a lot of mud. And one more problem that is important is if the PAM Puspiptek failed to supply fresh water to the reactor. So to handling and anticipate these things, necessary to optimize the deep well former Interatom legacy as a backup water supply for raw water supply system of the reactor. With a conductivity of 136 μS / cm, pH 7,4 and total hardness 37 ppm, the water from deep wells can be used as a backup supply of secondary raw water cooling system. (author)

Lithium-ion backup batteries for coping extended loss of AC power (ELAP)

International Nuclear Information System (INIS)

Chang, Choong-koo

2017-01-01

Per NRC Regulations Title 10, Code of Federal Regulations (CFR) 50.63 'Loss of all alternating current power' all Korean nuclear power plants have a coping capability for SBO conditions for a limited time ranging from approximately eight (8) to sixteen (16) hours. The 125V DC systems are designed for eight (8) hours range except Class 1E channel A and B 125V DC system of which duty cycle is 2 hours in APR1400. The strategies proposed by this paper for coping extended loss of AC power (ELAP) involve a three-phase approach. In the first extend class 1E batteries' backup time until 24 hours. Then augment class 1E batteries with Lithium-ion batteries by 72 hours from the event initiation. In addition, obtain additional capability and redundancy from off-site equipment until power systems are restored or commissioned. (author)

Satellite Cell Self-Renewal.

Science.gov (United States)

Giordani, Lorenzo; Parisi, Alice; Le Grand, Fabien

2018-01-01

Adult skeletal muscle is endowed with regenerative potential through partially recapitulating the embryonic developmental program. Upon acute injury or in pathological conditions, quiescent muscle-resident stem cells, called satellite cells, become activated and give rise to myogenic progenitors that massively proliferate, differentiate, and fuse to form new myofibers and restore tissue functionality. In addition, a proportion of activated cells returns back to quiescence and replenish the pool of satellite cells in order to maintain the ability of skeletal muscle tissue to repair. Self-renewal is the process by which stem cells divide to make more stem cells to maintain the stem cell population throughout life. This process is controlled by cell-intrinsic transcription factors regulated by cell-extrinsic signals from the niche and the microenvironment. This chapter provides an overview about the general aspects of satellite cell biology and focuses on the cellular and molecular aspects of satellite cell self-renewal. To date, we are still far from understanding how a very small proportion of the satellite cell progeny maintain their stem cell identity when most of their siblings progress through the myogenic program to construct myofibers. © 2018 Elsevier Inc. All rights reserved.

Application of programmable controllers to oil fired boiler light-off system

International Nuclear Information System (INIS)

Copeland, H.C.; Gallaway, E.N.

1978-01-01

A programmable controller has been used to improve the reliability of an oil-fired boiler burner control system. An outdated and failing Germanium discrete transistor logic control system was replaced with a modern solid state large scale integrated circuit programmable controller. The ease of making this conversion at a modest expenditure during a limited boiler outage is explained, as well as pitfalls and problems encountered. Light-off reliability with fuel savings were prime objectives. The boiler, rated at 575,000 lb/hr at 450 psig, is used as a backup steam supply for the dual purpose N Reactor at Hanford, Washington, which supplies 860 MWe to the Bonneville Power Administration and weapons grade Plutonium for the Department of Energy. High reliability in light-off and load ascension from standby is required of the boiler which serves as the backup power supply for the reactor

A COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF AIR FLOW THROUGH A TELECOM BACK-UP UNIT POWERED BY AN AIR-COOLED PROTON EXCHANGE MEMBRANE FUEL CELL

DEFF Research Database (Denmark)

Gao, Xin; Berning, Torsten; Kær, Søren Knudsen

2016-01-01

Proton exchange membrane fuel cells (PEMFC’s) are currently being commercialized for various applications ranging from automotive to stationary such as powering telecom back-up units. In PEMFC’s, oxygen from air is internally combined with hydrogen to form water and produce electricity and heat....... This product heat has to be effectively removed from the fuel cell, and while automotive fuel cells are usually liquid-cooled using a secondary coolant loop similar to the internal combustion engines, stationary fuel cell systems as they are used for telecom back-up applications often rely on excessive air fed...... to the fuel cell cathode to remove the heat. Thereby, the fuel cell system is much simpler and cheaper while the fuel cell performance is substantially lower compared to automotive fuel cells. This work presents a computational fluid dynamics analysis on the heat management of an air-cooled fuel cell powered...

Evolutionary design of a satellite thermal control system: Real experiments for a CubeSat mission

International Nuclear Information System (INIS)

Escobar, Emanuel; Diaz, Marcos; Zagal, Juan Cristóbal

2016-01-01

Highlights: • GAs applied to automate design of CubeSat passive thermal control system (coating). • Simulation adapted with real physical data (mockup experiment in vacuum chamber). • Obtained coating patterns consistently outperform engineered solutions (by 5 K). • Evolved coating patterns are far superior (by 8 K) than unpainted aluminum. - Abstract: This paper studies the use of artificial evolution to automate the design of a satellite passive thermal control system. This type of adaptation often requires the use of computer simulations to evaluate fitness of a large number of candidate solutions. Simulations are required to be expedient and accurate so that solutions can be successfully transferred to reality. We explore a design process that involves three steps. On a first step candidate solutions (implemented as surface paint tiling patterns) are tested using a FEM model and ranked according to their quality to meet mission temperature requirements. On a second step the best individual is implemented as a real physical satellite mockup and tested inside a vacuum chamber, having light sources imitating the effect of solar light. On a third step the simulation model is adapted with data obtained during the real evaluation. These updated models can be further employed for continuing genetic search. Current differences between our simulation and our real physical setup are in the order of 1.45 K mean squared error for faces pointing toward the light source and 2.4 K mean squared errors for shadowed faces. We found that evolved tiling patterns can be 5 K below engineered patterns and 8 K below using unpainted aluminum satellite surfaces.

Satellite ATM Networks: Architectures and Guidelines Developed

Science.gov (United States)

vonDeak, Thomas C.; Yegendu, Ferit

1999-01-01

An important element of satellite-supported asynchronous transfer mode (ATM) networking will involve support for the routing and rerouting of active connections. Work published under the auspices of the Telecommunications Industry Association (http://www.tiaonline.org), describes basic architectures and routing protocol issues for satellite ATM (SATATM) networks. The architectures and issues identified will serve as a basis for further development of technical specifications for these SATATM networks. Three ATM network architectures for bent pipe satellites and three ATM network architectures for satellites with onboard ATM switches were developed. The architectures differ from one another in terms of required level of mobility, supported data rates, supported terrestrial interfaces, and onboard processing and switching requirements. The documentation addresses low-, middle-, and geosynchronous-Earth-orbit satellite configurations. The satellite environment may require real-time routing to support the mobility of end devices and nodes of the ATM network itself. This requires the network to be able to reroute active circuits in real time. In addition to supporting mobility, rerouting can also be used to (1) optimize network routing, (2) respond to changing quality-of-service requirements, and (3) provide a fault tolerance mechanism. Traffic management and control functions are necessary in ATM to ensure that the quality-of-service requirements associated with each connection are not violated and also to provide flow and congestion control functions. Functions related to traffic management were identified and described. Most of these traffic management functions will be supported by on-ground ATM switches, but in a hybrid terrestrial-satellite ATM network, some of the traffic management functions may have to be supported by the onboard satellite ATM switch. Future work is planned to examine the tradeoffs of placing traffic management functions onboard a satellite as

Understanding satellite-based monthly-to-seasonal reservoir outflow estimation as a function of hydrologic controls

Science.gov (United States)

Bonnema, Matthew; Sikder, Safat; Miao, Yabin; Chen, Xiaodong; Hossain, Faisal; Ara Pervin, Ismat; Mahbubur Rahman, S. M.; Lee, Hyongki

2016-05-01

Growing population and increased demand for water is causing an increase in dam and reservoir construction in developing nations. When rivers cross international boundaries, the downstream stakeholders often have little knowledge of upstream reservoir operation practices. Satellite remote sensing in the form of radar altimetry and multisensor precipitation products can be used as a practical way to provide downstream stakeholders with the fundamentally elusive upstream information on reservoir outflow needed to make important and proactive water management decisions. This study uses a mass balance approach of three hydrologic controls to estimate reservoir outflow from satellite data at monthly and annual time scales: precipitation-induced inflow, evaporation, and reservoir storage change. Furthermore, this study explores the importance of each of these hydrologic controls to the accuracy of outflow estimation. The hydrologic controls found to be unimportant could potentially be neglected from similar future studies. Two reservoirs were examined in contrasting regions of the world, the Hungry Horse Reservoir in a mountainous region in northwest U.S. and the Kaptai Reservoir in a low-lying, forested region of Bangladesh. It was found that this mass balance method estimated the annual outflow of both reservoirs with reasonable skill. The estimation of monthly outflow from both reservoirs was however less accurate. The Kaptai basin exhibited a shift in basin behavior resulting in variable accuracy across the 9 year study period. Monthly outflow estimation from Hungry Horse Reservoir was compounded by snow accumulation and melt processes, reflected by relatively low accuracy in summer and fall, when snow processes control runoff. Furthermore, it was found that the important hydrologic controls for reservoir outflow estimation at the monthly time scale differs between the two reservoirs, with precipitation-induced inflow being the most important control for the Kaptai

Satellite power system in the service of man

Energy Technology Data Exchange (ETDEWEB)

Hyde, F.W.

1981-01-01

The solar power satellite concept is discussed in its various aspects: technical assumptions; unit power output; economic impact; impact on resources; environmental impacts; primary system functions; transmission of energy to earth; reception and conversion to usable energy on earth; space transport; station-keeping and attitude control; fabrication and assembly in space; power beam phase control; satellite maintenance; ancillary functions at rectenna site; and emerging technologies.

Tracking target objects orbiting earth using satellite-based telescopes

Science.gov (United States)

De Vries, Willem H; Olivier, Scot S; Pertica, Alexander J

2014-10-14

A system for tracking objects that are in earth orbit via a constellation or network of satellites having imaging devices is provided. An object tracking system includes a ground controller and, for each satellite in the constellation, an onboard controller. The ground controller receives ephemeris information for a target object and directs that ephemeris information be transmitted to the satellites. Each onboard controller receives ephemeris information for a target object, collects images of the target object based on the expected location of the target object at an expected time, identifies actual locations of the target object from the collected images, and identifies a next expected location at a next expected time based on the identified actual locations of the target object. The onboard controller processes the collected image to identify the actual location of the target object and transmits the actual location information to the ground controller.

The Implementation of Satellite Control System Software Using Object Oriented Design

Science.gov (United States)

Anderson, Mark O.; Reid, Mark; Drury, Derek; Hansell, William; Phillips, Tom

1998-01-01

NASA established the Small Explorer (SMEX) program in 1988 to provide frequent opportunities for highly focused and relatively inexpensive space science missions that can be launched into low earth orbit by small expendable vehicles. The development schedule for each SMEX spacecraft was three years from start to launch. The SMEX program has produced five satellites; Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX), Fast Auroral Snapshot Explorer (FAST), Submillimeter Wave Astronomy Satellite (SWAS), Transition Region and Coronal Explorer (TRACE) and Wide-Field Infrared Explorer (WIRE). SAMPEX and FAST are on-orbit, TRACE is scheduled to be launched in April of 1998, WIRE is scheduled to be launched in September of 1998, and SWAS is scheduled to be launched in January of 1999. In each of these missions, the Attitude Control System (ACS) software was written using a modular procedural design. Current program goals require complete spacecraft development within 18 months. This requirement has increased pressure to write reusable flight software. Object-Oriented Design (OOD) offers the constructs for developing an application that only needs modification for mission unique requirements. This paper describes the OOD that was used to develop the SMEX-Lite ACS software. The SMEX-Lite ACS is three-axis controlled, momentum stabilized, and is capable of performing sub-arc-minute pointing. The paper first describes the high level requirements which governed the architecture of the SMEX-Lite ACS software. Next, the context in which the software resides is explained. The paper describes the benefits of encapsulation, inheritance and polymorphism with respect to the implementation of an ACS software system. This paper will discuss the design of several software components that comprise the ACS software. Specifically, Object-Oriented designs are presented for sensor data processing, attitude control, attitude determination and failure detection. The paper addresses

The synchronization method for distributed small satellite SAR

Science.gov (United States)

Xing, Lei; Gong, Xiaochun; Qiu, Wenxun; Sun, Zhaowei

2007-11-01

One of critical requirement for distributed small satellite SAR is the trigger time precision when all satellites turning on radar loads. This trigger operation is controlled by a dedicated communication tool or GPS system. In this paper a hardware platform is proposed which has integrated navigation, attitude control, and data handling system together. Based on it, a probabilistic synchronization method is proposed for SAR time precision requirement with ring architecture. To simplify design of transceiver, half-duplex communication way is used in this method. Research shows that time precision is relevant to relative frequency drift rate, satellite number, retry times, read error and round delay length. Installed with crystal oscillator short-term stability 10 -11 magnitude, this platform can achieve and maintain nanosecond order time error with a typical three satellites formation experiment during whole operating process.

Future control room design (modernization of control room systems)

International Nuclear Information System (INIS)

Reischl, Ludwig; Freitag, Timo; Dergel, Rene

2009-01-01

In the frame of lifetime extension for nuclear power plants the modernization of the complete safety and operational control technology will be digitalized. It is also recommended to modernize the operator facilities, monitoring systems in the control room, the back-up shut-down center and the local control stations. The authors summarize the reasons for the modernization recommendations and discuss possible solutions for display-oriented control rooms. A concept for control room backfitting includes generic requirements, requirements of the local authorities, ergonomic principles information content and information density, and the design process. The backfitting strategy should include a cooperation with the operational personnel, The quality assurance and training via simulator needs sufficient timing during the implementation of the backfitting.

Enterprise Level Status and Control of Multi-Satellite Operations

Data.gov (United States)

National Aeronautics and Space Administration — Single-satellite mission operation centers are used for nearly all Goddard Space Flight Center (GSFC) mission ground data systems, with a focus on localized data...

Satellite Power Systems (SPS) concept definition study. Volume 5: Special emphasis studies. [rectenna and solar power satellite design studies

Science.gov (United States)

Hanley, G. M.

1980-01-01

Satellite configurations based on the Satellite Power System baseline requirements were analyzed and a preferred concept selected. A satellite construction base was defined, precursor operations incident to establishment of orbital support facilities identified, and the satellite construction sequence and procedures developed. Rectenna construction requirement were also addressed. Mass flow to orbit requirements were revised and traffic models established based on construction of 60 instead of 120 satellites. Analyses were conducted to determine satellite control, resources, manufacturing, and propellant requirements. The impact of the laser beam used for space-to-Earth power transmission upon the intervening atmosphere was examined as well as the inverse effect. The significant space environments and their effects on spacecraft components were investigated to define the design and operational limits imposed by the environments on an orbit transfer vehicle. The results show that LEO altitude 300 nmi and transfer orbit duration 6 months are preferrable.

HEXIM1 controls satellite cell expansion after injury to regulate skeletal muscle regeneration

Science.gov (United States)

Hong, Peng; Chen, Kang; Huang, Bihui; Liu, Min; Cui, Miao; Rozenberg, Inna; Chaqour, Brahim; Pan, Xiaoyue; Barton, Elisabeth R.; Jiang, Xian-Cheng; Siddiqui, M.A.Q.

2012-01-01

The native capacity of adult skeletal muscles to regenerate is vital to the recovery from physical injuries and dystrophic diseases. Currently, the development of therapeutic interventions has been hindered by the complex regulatory network underlying the process of muscle regeneration. Using a mouse model of skeletal muscle regeneration after injury, we identified hexamethylene bisacetamide inducible 1 (HEXIM1, also referred to as CLP-1), the inhibitory component of the positive transcription elongation factor b (P-TEFb) complex, as a pivotal regulator of skeletal muscle regeneration. Hexim1-haplodeficient muscles exhibited greater mass and preserved function compared with those of WT muscles after injury, as a result of enhanced expansion of satellite cells. Transplanted Hexim1-haplodeficient satellite cells expanded and improved muscle regeneration more effectively than WT satellite cells. Conversely, HEXIM1 overexpression restrained satellite cell proliferation and impeded muscle regeneration. Mechanistically, dissociation of HEXIM1 from P-TEFb and subsequent activation of P-TEFb are required for satellite cell proliferation and the prevention of early myogenic differentiation. These findings suggest a crucial role for the HEXIM1/P-TEFb pathway in the regulation of satellite cell–mediated muscle regeneration and identify HEXIM1 as a potential therapeutic target for degenerative muscular diseases. PMID:23023707

Miniature Reaction Wheel for Small Satellite Control, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The overall goal of this project is to design, develop, demonstrate, and deliver a miniature, high torque, low-vibration reaction wheel for use on small satellites....

Control of GABARAP-mediated autophagy by the Golgi complex, centrosome and centriolar satellites.

Science.gov (United States)

Joachim, Justin; Tooze, Sharon A

2018-01-01

Within minutes of induction of autophagy by amino-acid starvation in mammalian cells, multiple autophagosomes form throughout the cell cytoplasm. During their formation, the autophagosomes sequester cytoplasmic material and deliver it to lysosomes for degradation. How these organelles can be so rapidly formed and how their formation is acutely regulated are major questions in the autophagy field. Protein and lipid trafficking from diverse cell compartments contribute membrane to, or regulate the formation of the autophagosome. In addition, recruitment of Atg8 (in yeast), and the ATG8-family members (in mammalian cells) to autophagosomes is required for efficient autophagy. Recently, it was discovered that the centrosome and centriolar satellites regulate autophagosome formation by delivery of an ATG8-family member, GABARAP, to the forming autophagosome membrane, the phagophore. We propose that GABARAP regulates phagophore expansion by activating the ULK complex, the amino-acid controlled initiator complex. This finding reveals a previously unknown link between the centrosome, centriolar satellites and autophagy. © 2017 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

Odyssey, an optimized personal communications satellite system

Science.gov (United States)

Rusch, Roger J.

Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry is developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, "bent pipe" transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 Watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. There are three orbit planes inclined at 55° to the equatorial plane

Screen-based process control in nuclear plants

International Nuclear Information System (INIS)

Hinz, W.; Arnoldt, C.; Hessler, C.

1993-01-01

Requirements, development and conceptual design of a screen-based control room for nuclear power plants are outlined. The control room consists of three or four equally equipped operator workstations comprising screens for process information and manual process control. A plant overview will assist the coordination among the operators. A safety classified backup system (safety control area) is provided to cover postulated failures of the control means. Some aspects of ergonomical validation and of future development trends are discussed. (orig.) [de

An FPGA based backup version of the TileCal digitizer

International Nuclear Information System (INIS)

Eriksson, D; Muschter, S; Bohm, C

2010-01-01

The ATLAS Tile Calorimeter front end digitization and readout system comprises about 1800 digitizer boards with two TileDMU ASICs on each board. The TileDMUs are responsible for storing, derandomising and reading out digitized data from twelve ADCs. An ample number of board spares are available. However, a backup solution is desirable in the event of unexpected failure modes. The original version contains both outdated and custom made circuits that are difficult or impossible to find in sufficient numbers. We have developed a new version using inexpensive off the shelf FPGAs (Spartan 6). The FPGAs have all the necessary functionality to emulate the TileDMU and will be readily available for a considerable time. The new board is functionally compatible with the current version and to a large extent uses the same code. The design goal was to leave the digitizer design as intact as possible since it is well tested and performs well. As radiation tolerance is an issue we have implemented triple mode redundancy in the FPGA. To further improve the system we added in system programmability via TTCrx for both the FPGA and the configuration memory using one way JTAG. This provides a way to recover from radiation damage to the configuration PROM or to remotely upgrade system firmware.

An FPGA based backup version of the TileCal digitizer.

Science.gov (United States)

Eriksson, D.; Muschter, S.; Bohm, C.

2010-11-01

The ATLAS Tile Calorimeter front end digitization and readout system comprises about 1800 digitizer boards with two TileDMU ASICs on each board. The TileDMUs are responsible for storing, derandomising and reading out digitized data from twelve ADCs. An ample number of board spares are available. However, a backup solution is desirable in the event of unexpected failure modes. The original version contains both outdated and custom made circuits that are difficult or impossible to find in sufficient numbers. We have developed a new version using inexpensive off the shelf FPGAs (Spartan 6). The FPGAs have all the necessary functionality to emulate the TileDMU and will be readily available for a considerable time. The new board is functionally compatible with the current version and to a large extent uses the same code. The design goal was to leave the digitizer design as intact as possible since it is well tested and performs well. As radiation tolerance is an issue we have implemented triple mode redundancy in the FPGA. To further improve the system we added in system programmability via TTCrx for both the FPGA and the configuration memory using one way JTAG. This provides a way to recover from radiation damage to the configuration PROM or to remotely upgrade system firmware.

Testing command and control of the satellites in formation flight

Science.gov (United States)

Gheorghe, Popan; Gheorghe, Gh. Ion; Gabriel, Todoran

2013-10-01

The topics covered in the paper are mechatronic systems for determining the distance between the satellites and the design of the displacement system on air cushion table for satellites testing. INCDMTM has the capability to approach the collaboration within European Programms (ESA) of human exploration of outer space through mechatronic systems and accessories for telescopes, mechatronics systems used by the launchers, sensors and mechatronic systems for the robotic exploration programs of atmosphere and Mars. This research has a strong development component of industrial competitiveness many of the results of space research have direct applicability in industrial fabrication.

Tracking and data relay satellite system (TDRSS) capabilities

Science.gov (United States)

Spearing, R. E.

1985-10-01

The Tracking and Data Relay Satellite System (TDRSS) is the latest implementation to tracking and data acquisition network for near-earth orbiting satellite support designed to meet the requirements of the current and projected (to the year 2000) satellite user community. The TDRSS consists of a space segment (SS) and a ground segment (GS) that fit within NASA's Space Network (SN) complex controlled at the Goddard Space Flight Center. The SS currently employs a single satellite, TDRS-1, with two additional satellites to be deployed in January 1986 and July 1986. The GS contains the communications and equipment required to manage the three TDR satellites and to transmit and receive information to and from TDRSS user satellites. Diagrams and tables illustrating the TDRSS signal characteristics, the situation of TDRSS within the SN, the SN operations and element interrelationships, as well as future plans for new missions are included.

Dynamic control modeling and simulation of a UPFC–SMES compensator in power systems

Directory of Open Access Journals (Sweden)

Saravanan Kandasamy

2015-12-01

Full Text Available Flexible AC Transmission Systems (FACTS is granting a new group of advanced power electronic devices emerging for the enhancement of the power system performance. Unified Power Flow Controller (UPFC is a recent version of FACTS devices for power system applications. The back-up energy supply system incorporated with UPFC is providing a complete control of real and reactive power at the same time and hence is competent to improve the performance of an electrical power system. In this article, backup energy supply units such as superconducting magnetic energy storage (SMES are integrated with UPFC. In addition, comparative exploration of UPFC–battery, UPFC–UC and UPFC–SMES performance is evaluated through the vibrant simulation by using MATLAB/Simulink software.

Saturn satellites

International Nuclear Information System (INIS)

Ruskol, E.L.

1981-01-01

The characteristics of the Saturn satellites are discussed. The satellites close to Saturn - Janus, Mimas, Enceladus, Tethys, Dione and Rhea - rotate along the circular orbits. High reflectivity is attributed to them, and the density of the satellites is 1 g/cm 3 . Titan is one of the biggest Saturn satellites. Titan has atmosphere many times more powerful than that of Mars. The Titan atmosphere is a peculiar medium with a unique methane and hydrogen distribution in the whole Solar system. The external satellites - Hyperion, Japetus and Phoebe - are poorly investigated. Neither satellite substance density, nor their composition are known. The experimental data on the Saturn rings obtained on the ''Pioneer-11'' and ''Voyager-1'' satellites are presented [ru

Optical burst switching based satellite backbone network

Science.gov (United States)

Li, Tingting; Guo, Hongxiang; Wang, Cen; Wu, Jian

2018-02-01

We propose a novel time slot based optical burst switching (OBS) architecture for GEO/LEO based satellite backbone network. This architecture can provide high speed data transmission rate and high switching capacity . Furthermore, we design the control plane of this optical satellite backbone network. The software defined network (SDN) and network slice (NS) technologies are introduced. Under the properly designed control mechanism, this backbone network is flexible to support various services with diverse transmission requirements. Additionally, the LEO access and handoff management in this network is also discussed.

Equilibria of a charged artificial satellite subject to gravitational and Lorentz torques

International Nuclear Information System (INIS)

Abdel-Aziz, Yehia A.; Shoaib, Muhammad

2014-01-01

The attitude dynamics of a rigid artificial satellite subject to a gravity gradient and Lorentz torques in a circular orbit are considered. Lorentz torque is developed on the basis of the electrodynamic effects of the Lorentz force acting on the charged satellite's surface. We assume that the satellite is moving in a Low Earth Orbit in the geomagnetic field, which is considered to be a dipole. Our model of torque due to the Lorentz force is developed for an artificial satellite with a general shape, and the nonlinear differential equations of Euler are used to describe its attitude orientation. All equilibrium positions are determined and conditions for their existence are obtained. The numerical results show that the charge q and radius ρ 0 of the center of charge for the satellite provide a certain type of semi-passive control for the attitude of the satellite. The technique for this kind of control would be to increase or decrease the electrostatic screening on the satellite. The results obtained confirm that the change in charge can affect the magnitude of the Lorentz torque, which can also affect control of the satellite. Moreover, the relationship between magnitude of the Lorentz torque and inclination of the orbit is investigated. (research papers)

Equilibria of a charged artificial satellite subject to gravitational and Lorentz torques

Science.gov (United States)

Abdel-Aziz, Yehia A.; Shoaib, Muhammad

2014-07-01

The attitude dynamics of a rigid artificial satellite subject to a gravity gradient and Lorentz torques in a circular orbit are considered. Lorentz torque is developed on the basis of the electrodynamic effects of the Lorentz force acting on the charged satellite's surface. We assume that the satellite is moving in a Low Earth Orbit in the geomagnetic field, which is considered to be a dipole. Our model of torque due to the Lorentz force is developed for an artificial satellite with a general shape, and the nonlinear differential equations of Euler are used to describe its attitude orientation. All equilibrium positions are determined and conditions for their existence are obtained. The numerical results show that the charge q and radius ρ0 of the center of charge for the satellite provide a certain type of semi-passive control for the attitude of the satellite. The technique for this kind of control would be to increase or decrease the electrostatic screening on the satellite. The results obtained confirm that the change in charge can affect the magnitude of the Lorentz torque, which can also affect control of the satellite. Moreover, the relationship between magnitude of the Lorentz torque and inclination of the orbit is investigated.

A satellite-tracking millimeter-wave reflector antenna system for mobile satellite-tracking

Science.gov (United States)

Densmore, Arthur C.; Jamnejad, Vahraz; Woo, Kenneth E.

1995-03-01

A miniature dual-band two-way mobile satellite tracking antenna system mounted on a movable ground vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal.

Web Transfer Over Satellites Being Improved

Science.gov (United States)

Allman, Mark

1999-01-01

Extensive research conducted by NASA Lewis Research Center's Satellite Networks and Architectures Branch and the Ohio University has demonstrated performance improvements in World Wide Web transfers over satellite-based networks. The use of a new version of the Hypertext Transfer Protocol (HTTP) reduced the time required to load web pages over a single Transmission Control Protocol (TCP) connection traversing a satellite channel. However, an older technique of simultaneously making multiple requests of a given server has been shown to provide even faster transfer time. Unfortunately, the use of multiple simultaneous requests has been shown to be harmful to the network in general. Therefore, we are developing new mechanisms for the HTTP protocol which may allow a single request at any given time to perform as well as, or better than, multiple simultaneous requests. In the course of study, we also demonstrated that the time for web pages to load is at least as short via a satellite link as it is via a standard 28.8-kbps dialup modem channel. This demonstrates that satellites are a viable means of accessing the Internet.

The Study of a Super Low Altitude Satellite

Science.gov (United States)

Noda, Atsushi; Homma, Masanori; Utashima, Masayoshi

This paper reports the result of a study for super low altitude satellite. The altitude of this satellite's orbit is lower than ever. The altitude of a conventional earth observing satellite is generally around from 600km to 900km. The lowest altitude of earth observing satellite launched in Japan was 350km; the Tropical Rainfall Measuring Mission (TRMM). By comparison, the satellite reported in this paper is much lower than that and it is planned to orbit below 200km. Furthermore, the duration of the flight planned is more than two years. Any satellite in the world has not achieved to keep such a low altitude that long term. The satellite in such a low orbit drops quickly because of the strong air drag. Our satellite will cancel the air drag effect by ion engine thrust. To realize this idea, a drag-free system will be applied. This usually leads a complicated and expensive satellite system. We, however, succeeded in finding a robust control law for a simple system even under the unpredictable change of air drag. When the altitude of the satellite is lowered successfully, the spatial resolution of an optical sensor can be highly improved. If a SAR is equipped with the satellite, it enables the drastic reduction of electric power consumption and the fabulous spatial resolution improvement at the same time.

Fibromodulin: a master regulator of myostatin controlling progression of satellite cells through a myogenic program.

Science.gov (United States)

Lee, Eun Ju; Jan, Arif Tasleem; Baig, Mohammad Hassan; Ashraf, Jalaluddin Mohammad; Nahm, Sang-Soep; Kim, Yong-Woon; Park, So-Young; Choi, Inho

2016-08-01

Differentiation of muscle satellite cells (MSCs) involves interaction of the proteins present in the extracellular matrix (ECM) with MSCs to regulate their activity, and therefore phenotype. Herein, we report fibromodulin (FMOD), a member of the proteoglycan family participating in the assembly of ECM, as a novel regulator of myostatin (MSTN) during myoblast differentiation. In addition to having a pronounced effect on the expression of myogenic marker genes [myogenin (MYOG) and myosin light chain 2 (MYL2)], FMOD was found to maintain the transcriptional activity of MSTN Moreover, coimmunoprecipitation and in silico studies performed to investigate the interaction of FMOD helped confirm that it antagonizes MSTN function by distorting its folding and preventing its binding to activin receptor type IIB. Furthermore, in vivo studies revealed that FMOD plays an active role in healing by increasing satellite cell recruitment to sites of injury. Together, these findings disclose a hitherto unrecognized regulatory role for FMOD in MSCs and highlight new mechanisms whereby FMOD circumvents the inhibitory effects of MSTN and triggers myoblast differentiation. These findings offer a basis for the design of novel MSTN inhibitors that promote muscle regeneration after injury or for the development of pharmaceutical agents for the treatment of different muscle atrophies.-Lee, E. J., Jan, A. T., Baig, M. H., Ashraf, J. M., Nahm, S.-S., Kim, Y.-W., Park, S.-Y., Choi, I. Fibromodulin: a master regulator of myostatin controlling progression of satellite cells through a myogenic program. © FASEB.

Altered Satellite Cell Responsiveness and Denervation Implicated in Progression of Rotator-Cuff Injury.

Directory of Open Access Journals (Sweden)

Deanna Gigliotti

Full Text Available Rotator-cuff injury (RCI is common and painful; even after surgery, joint stability and function may not recover. Relative contributions to atrophy from disuse, fibrosis, denervation, and satellite-cell responsiveness to activating stimuli are not known.Potential contributions of denervation and disrupted satellite cell responses to growth signals were examined in supraspinatus (SS and control (ipsilateral deltoid muscles biopsied from participants with RCI (N = 27. Biopsies were prepared for explant culture (to study satellite cell activity, immunostained to localize Pax7, BrdU, and Semaphorin 3A in satellite cells, sectioning to study blood vessel density, and western blotting to measure the fetal (γ subunit of acetylcholine receptor (γ-AchR. Principal component analysis (PCA for 35 parameters extracted components identified variables that contributed most to variability in the dataset. γ-AchR was higher in SS than control, indicating denervation. Satellite cells in SS had a low baseline level of activity (Pax7+ cells labelled in S-phase versus control; only satellite cells in SS showed increased proliferative activity after nitric oxide-donor treatment. Interestingly, satellite cell localization of Semaphorin 3A, a neuro-chemorepellent, was greater in SS (consistent with fiber denervation than control muscle at baseline. PCAs extracted components including fiber atrophy, satellite cell activity, fibrosis, atrogin-1, smoking status, vascular density, γAchR, and the time between symptoms and surgery. Use of deltoid as a control for SS was supported by PCA findings since "muscle" was not extracted as a variable in the first two principal components. SS muscle in RCI is therefore atrophic, denervated, and fibrotic, and has satellite cells that respond to activating stimuli.Since SS satellite cells can be activated in culture, a NO-donor drug combined with stretching could promote muscle growth and improve functional outcome after RCI. PCAs

Altered Satellite Cell Responsiveness and Denervation Implicated in Progression of Rotator-Cuff Injury.

Science.gov (United States)

Gigliotti, Deanna; Leiter, Jeff R S; MacDonald, Peter B; Peeler, Jason; Anderson, Judy E

Rotator-cuff injury (RCI) is common and painful; even after surgery, joint stability and function may not recover. Relative contributions to atrophy from disuse, fibrosis, denervation, and satellite-cell responsiveness to activating stimuli are not known. Potential contributions of denervation and disrupted satellite cell responses to growth signals were examined in supraspinatus (SS) and control (ipsilateral deltoid) muscles biopsied from participants with RCI (N = 27). Biopsies were prepared for explant culture (to study satellite cell activity), immunostained to localize Pax7, BrdU, and Semaphorin 3A in satellite cells, sectioning to study blood vessel density, and western blotting to measure the fetal (γ) subunit of acetylcholine receptor (γ-AchR). Principal component analysis (PCA) for 35 parameters extracted components identified variables that contributed most to variability in the dataset. γ-AchR was higher in SS than control, indicating denervation. Satellite cells in SS had a low baseline level of activity (Pax7+ cells labelled in S-phase) versus control; only satellite cells in SS showed increased proliferative activity after nitric oxide-donor treatment. Interestingly, satellite cell localization of Semaphorin 3A, a neuro-chemorepellent, was greater in SS (consistent with fiber denervation) than control muscle at baseline. PCAs extracted components including fiber atrophy, satellite cell activity, fibrosis, atrogin-1, smoking status, vascular density, γAchR, and the time between symptoms and surgery. Use of deltoid as a control for SS was supported by PCA findings since "muscle" was not extracted as a variable in the first two principal components. SS muscle in RCI is therefore atrophic, denervated, and fibrotic, and has satellite cells that respond to activating stimuli. Since SS satellite cells can be activated in culture, a NO-donor drug combined with stretching could promote muscle growth and improve functional outcome after RCI. PCAs suggest

Development of a green bipropellant hydrogen peroxide thruster for attitude control on satellites

Science.gov (United States)

Woschnak, A.; Krejci, D.; Schiebl, M.; Scharlemann, C.

2013-03-01

This document describes the selection assessment of propellants for a 1-newton green bipropellant thruster for attitude control on satellites. The development of this thruster was conducted as a part of the project GRASP (Green Advanced Space Propellants) within the European FP7 research program. The green propellant combinations hydrogen peroxide (highly concentrated with 87.5 %(wt.)) with kerosene or hydrogen peroxide (87.5 %(wt.)) with ethanol were identified as interesting candidates and were investigated in detail with the help of an experimental combustion chamber in the chemical propulsion laboratory at the Forschungsund Technologietransfer GmbH ― Fotec. Based on the test results, a final selection of propellants was performed.

Pipeline Analyzer using the Fractional Fourier Transform for Engine Control and Satellites Data

Directory of Open Access Journals (Sweden)

Darian M. Onchiș

2011-09-01

Full Text Available The aim of this paper is to present an algorithm for computing the fractional Fourier transform integrated into the pipeline of processing multi-variate and distributed data recorded by the engine control unit (ECU of a car and its satellites. The role of this transform is vital in establishing a time-variant filter and therefore it must be computed in a fast way. But for large scale time series, the application of the discrete fractional Fourier transform involves the computations of a large number of Hermite polynomials of increasingly order. The parallel algorithm presented will optimally compute the discrete Fourier-type transform for any given angle.

Solar dryer with thermal storage and biomass-backup heater

Energy Technology Data Exchange (ETDEWEB)

Madhlopa, A. [Department of Physics and Biochemical Sciences, Malawi Polytechnic, P/Bag 303, Blantyre 3 (Malawi); Ngwalo, G. [Department of Mechanical Engineering, Malawi Polytechnic, P/Bag 303, Blantyre 3 (Malawi)

2007-04-15

An indirect type natural convection solar dryer with integrated collector-storage solar and biomass-backup heaters has been designed, constructed and evaluated. The major components of the dryer are biomass burner (with a rectangular duct and flue gas chimney), collector-storage thermal mass and drying chamber (with a conventional solar chimney). The thermal mass was placed in the top part of the biomass burner enclosure. The dryer was fabricated using simple materials, tools and skills, and it was tested in three modes of operation (solar, biomass and solar-biomass) by drying twelve batches of fresh pineapple (Ananas comosus), with each batch weighing about 20 kg. Meteorological conditions were monitored during the dehydration process. Moisture and vitamin C contents were determined in both fresh and dried samples. Results show that the thermal mass was capable of storing part of the absorbed solar energy and heat from the burner. It was possible to dry a batch of pineapples using solar energy only on clear days. Drying proceeded successfully even under unfavorable weather conditions in the solar-biomass mode of operation. In this operational mode, the dryer reduced the moisture content of pineapple slices from about 669 to 11% (db) and yielded a nutritious dried product. The average values of the final-day moisture-pickup efficiency were 15%, 11% and 13% in the solar, biomass and solar-biomass modes of operation respectively. It appears that the solar dryer is suitable for preservation of pineapples and other fresh foods. Further improvements to the system design are suggested. (author)

DC Control Effort Minimized for Magnetic-Bearing-Supported Shaft

Science.gov (United States)

Brown, Gerald V.

2001-01-01

A magnetic-bearing-supported shaft may have a number of concentricity and alignment problems. One of these involves the relationship of the position sensors, the centerline of the backup bearings, and the magnetic center of the magnetic bearings. For magnetic bearings with permanent magnet biasing, the average control current for a given control axis that is not bearing the shaft weight will be minimized if the shaft is centered, on average over a revolution, at the magnetic center of the bearings. That position may not yield zero sensor output or center the shaft in the backup bearing clearance. The desired shaft position that gives zero average current can be achieved if a simple additional term is added to the control law. Suppose that the instantaneous control currents from each bearing are available from measurements and can be input into the control computer. If each control current is integrated with a very small rate of accumulation and the result is added to the control output, the shaft will gradually move to a position where the control current averages to zero over many revolutions. This will occur regardless of any offsets of the position sensor inputs. At that position, the average control effort is minimized in comparison to other possible locations of the shaft. Nonlinearities of the magnetic bearing are minimized at that location as well.

A network architecture for International Business Satellite communications

Science.gov (United States)

Takahata, Fumio; Nohara, Mitsuo; Takeuchi, Yoshio

Demand Assignment (DA) control is expected to be introduced in the International Business Satellte communications (IBS) network in order to cope with a growing international business traffic. The paper discusses the DA/IBS network from the viewpoints of network configuration, satellite channel configuration and DA control. The network configuration proposed here consists of one Central Station with network management function and several Network Coordination Stations with user management function. A satellite channel configuration is also presented along with a tradeoff study on transmission bit rate, high power amplifier output power requirement, and service quality. The DA control flow and protocol based on CCITT Signalling System No. 7 are also proposed.

Interpretation of Ersec tests on the backup cooling of pressurized water reactors, by using the FLIRA code

International Nuclear Information System (INIS)

Reviglio, Christiane

1977-01-01

This research thesis addresses the study of the most severe accident, or reference accident, which might occur in nuclear reactors, a clean break of a cold branch of the primary circuit, which may put the integrity of barriers against radioactive products dispersion outside of the reactor into question again. More particularly, the thesis addresses the study of the backup cooling system, and the fact that fluid flow during re-flooding must be predicted, and that heat exchange coefficients must be known in order to assess the evolution of sheath temperatures. The research comprised an experimental part which aimed at reproducing as faithfully as possible the re-flooding sequence on a tube with internal flow or on a cluster for a better core simulation. These are the ERSEC tests which are to be interpreted. It also comprised a theoretical part based on the use of computational codes which simulate the different phases of the accident and of backup fluid injection. These codes are based on physical models which describe two-phase flows and heat exchanges, and are adjusted to experimental results. The FLIRA code is used which simulates the re-flooding of a reactor duct, and determines the evolution of different values (pressure, temperatures, flow rate, and so on) during the re-flooding process. Thus, the author presents the reference accident, reports studies performed in the USA and in France (ERSEC tests), indicates the various flow regimes and describes heat exchange mechanisms during re-flooding, presents ERSEC test results, presents the FLIRA code, reports the elaboration of governing equations, indicates the various models introduced in the FLIRA code, and describes the numerical processing of equations. He finally gives a first interpretation of ERSEC tests based on the use of the FLIRA code

The development of ZPRL digital control system

International Nuclear Information System (INIS)

Hsu, Jin-Den; Yang, Sheau-Yieh; Shieh, Der-Jhy.

1992-01-01

Zero Power Reactor at Lung-Tan (ZPRL) is a small open-pool type research reactor located at Lung-Tan, Taiwan. The reactor achieved its first criticality in 1971. An analog control system has been used for almost over 20 years and the power regulating function is found gradually out of order. Therefore, we decided to develop a digital control system to replace the existing analog one. A prototype system has been developed and under on-line test now. The proposed ZPRL digital control system consists of three personal computers. These computers are used as (1) operator console, (2) data acquisition and control system, and (3) auxiliary and backup system. The operator console contains all the man-machine interface functions in the form of graphic display. The data acquisition and control system converts the analog signals into digital ones and feeds to the other two computers. The auxiliary and backup system normally emulates a strip chart recorder for the linear and logarithmic neutron powers and also acts as a transient recorder to keep the trace of the operating conditions on demand or when the reactor scrams. On-line test shows that the system does assure a satisfactory performance. It is not only as good as the analog system but also has the advantages of flexibility, testibility, and a user friendly man-machine interface. (author)

Advanced Satellite Workstation - An integrated workstation environment for operational support of satellite system planning and analysis

Science.gov (United States)

Hamilton, Marvin J.; Sutton, Stewart A.

A prototype integrated environment, the Advanced Satellite Workstation (ASW), which was developed and delivered for evaluation and operator feedback in an operational satellite control center, is described. The current ASW hardware consists of a Sun Workstation and Macintosh II Workstation connected via an ethernet Network Hardware and Software, Laser Disk System, Optical Storage System, and Telemetry Data File Interface. The central objective of ASW is to provide an intelligent decision support and training environment for operator/analysis of complex systems such as satellites. Compared to the many recent workstation implementations that incorporate graphical telemetry displays and expert systems, ASW provides a considerably broader look at intelligent, integrated environments for decision support, based on the premise that the central features of such an environment are intelligent data access and integrated toolsets.

Protected transitional solution to transformational satellite communications

Science.gov (United States)

Brand, Jerry C.

2005-06-01

As the Warfighter progresses into the next generation battlefield, transformational communications become evident as an enabling technology. Satellite communications become even more vital as the battles range over greater non-contiguous spaces. While current satellite communications provide suitable beyond line-of-sight communications and the Transformational Communications Architecture (TCA) sets the stage for sound information exchange, a realizable transition must occur to ensure successful succession to this higher level. This paper addresses the need for a planned escalation to the next generation satellite communications architecture and offers near-term alternatives. Commercial satellite systems continue to enable the Warfighter to reach back to needed information resources, providing a large majority of available bandwidth. Four areas of concentration for transition include encrypted Telemetry, Tracking and Control (or Command) (TT&C), encrypted and covered data, satellite attack detection and protection, and operational mobility. Solution methodologies include directly embedding COMSEC devices in the satellites and terminals, and supplementing existing terminals with suitable equipment and software. Future satellites planned for near-term launches can be adapted to include commercial grade and higher-level secure equipment. Alternately, the expected use of programmable modems (Software Defined Radios (SDR)) enables incorporation of powerful cipher methods approaching military standards as well as waveforms suitable for on-the-move operation. Minimal equipment and software additions on the satellites can provide reasonable attack detection and protection methods in concert with the planned satellite usage. Network management suite modifications enable cohesive incorporation of these protection schemes. Such transitional ideas offer a smooth and planned transition as the TCA takes life.

The Design and Application of Data Storage System in Miyun Satellite Ground Station

Science.gov (United States)

Xue, Xiping; Su, Yan; Zhang, Hongbo; Liu, Bin; Yao, Meijuan; Zhao, Shu

2015-04-01

China has launched Chang'E-3 satellite in 2013, firstly achieved soft landing on moon for China's lunar probe. Miyun satellite ground station firstly used SAN storage network system based-on Stornext sharing software in Chang'E-3 mission. System performance fully meets the application requirements of Miyun ground station data storage.The Stornext file system is a sharing file system with high performance, supports multiple servers to access the file system using different operating system at the same time, and supports access to data on a variety of topologies, such as SAN and LAN. Stornext focused on data protection and big data management. It is announced that Quantum province has sold more than 70,000 licenses of Stornext file system worldwide, and its customer base is growing, which marks its leading position in the big data management.The responsibilities of Miyun satellite ground station are the reception of Chang'E-3 satellite downlink data and management of local data storage. The station mainly completes exploration mission management, receiving and management of observation data, and provides a comprehensive, centralized monitoring and control functions on data receiving equipment. The ground station applied SAN storage network system based on Stornext shared software for receiving and managing data reliable.The computer system in Miyun ground station is composed by business running servers, application workstations and other storage equipments. So storage systems need a shared file system which supports heterogeneous multi-operating system. In practical applications, 10 nodes simultaneously write data to the file system through 16 channels, and the maximum data transfer rate of each channel is up to 15MB/s. Thus the network throughput of file system is not less than 240MB/s. At the same time, the maximum capacity of each data file is up to 810GB. The storage system planned requires that 10 nodes simultaneously write data to the file system through 16

The Implementation of Satellite Attitude Control System Software Using Object Oriented Design

Science.gov (United States)

Reid, W. Mark; Hansell, William; Phillips, Tom; Anderson, Mark O.; Drury, Derek

1998-01-01

NASA established the Small Explorer (SNMX) program in 1988 to provide frequent opportunities for highly focused and relatively inexpensive space science missions. The SMEX program has produced five satellites, three of which have been successfully launched. The remaining two spacecraft are scheduled for launch within the coming year. NASA has recently developed a prototype for the next generation Small Explorer spacecraft (SMEX-Lite). This paper describes the object-oriented design (OOD) of the SMEX-Lite Attitude Control System (ACS) software. The SMEX-Lite ACS is three-axis controlled and is capable of performing sub-arc-minute pointing. This paper first describes high level requirements governing the SMEX-Lite ACS software architecture. Next, the context in which the software resides is explained. The paper describes the principles of encapsulation, inheritance, and polymorphism with respect to the implementation of an ACS software system. This paper will also discuss the design of several ACS software components. Specifically, object-oriented designs are presented for sensor data processing, attitude determination, attitude control, and failure detection. Finally, this paper will address the establishment of the ACS Foundation Class (AFC) Library. The AFC is a large software repository, requiring a minimal amount of code modifications to produce ACS software for future projects.

Backup pathways of NHEJ in cells of higher eukaryotes: Cell cycle dependence

International Nuclear Information System (INIS)

Iliakis, George

2009-01-01

DNA double-strand breaks (DSBs) induced by ionizing radiation (IR) in cells of higher eukaryotes are predominantly repaired by a pathway of non-homologous end joining (NHEJ) utilizing Ku, DNA-PKcs, DNA ligase IV, XRCC4 and XLF/Cernunnos (D-NHEJ) as central components. Work carried out in our laboratory and elsewhere shows that when this pathway is chemically or genetically compromised, cells do not shunt DSBs to homologous recombination repair (HRR) but instead use another form of NHEJ operating as a backup (B-NHEJ). Here I review our efforts to characterize this repair pathway and discuss its dependence on the cell cycle as well as on the growth conditions. I present evidence that B-NHEJ utilizes ligase III, PARP-1 and histone H1. When B-NHEJ is examined throughout the cell cycle, significantly higher activity is observed in G2 phase that cannot be attributed to HRR. Furthermore, the activity of B-NHEJ is compromised when cells enter the plateau phase of growth. Together, these observations uncover a repair pathway with unexpected biochemical constitution and interesting cell cycle and growth factor regulation. They generate a framework for investigating the mechanistic basis of HRR contribution to DSB repair.

About Nano-JASMINE Satellite System and Project Status

Science.gov (United States)

Sako, Nobutada

Intelligent Space Systems Laboratory, The University of Tokyo (ISSL) and National Astronomical Observatory of Japan (NAO) have been developing a small infrared astrometry satellite named “Nano-JASMINE”. The satellite size is about 50cm cubic and 20kg, which plays a pre-cursor role of JASMINE Project which is programmed by NAO and JAXA. In addition, since there has been only one astrometry satellite HIPPARCOS by ESA in the past, Nano-JASMINE is also expected to achieve certain scientific results in the field of astrometry. In this project, ISSL aims to develop new advanced small satellite bus system whose performance is comparable to that of 100-500kg sized satellites, including attitude stability of 1 arc-second and thermal stability of the mission subsystem of 1 mK. This paper overviews the Nano-JASMINE bus system with emphasis on attitude and thermal control systems.

Guidelines for control room systems design. Working material. Report

International Nuclear Information System (INIS)

1993-01-01

This report contains comprehensive technical and methodological information and recommendations for the benefit of Member States for advice and assistance in ''NPP control room systems'' design backfitting existing nuclear power plants and design for future stations. The term ''Control Room Systems'' refers to the entire human/machine interface for the nuclear stations - including the main control room, back-ups control room and the emergency control rooms, local panels, technical support centres, operating staff, operating procedures, operating training programs, communications, etc. Refs, figs and tabs

Electrophotometric observations of artificial satellites

International Nuclear Information System (INIS)

Vovchyk, Yeva; Blagodyr, Yaroslav; Kraynyuk, Gennadiy; Bilinsky, Andriy; Lohvynenko, Alexander; Klym, Bogdan; Pochapsky, Yevhen

2004-01-01

Problems associated with polarimetric observations of low Earth orbit artificial satellites as important solar system objects are discussed. The instrumentation (the optical and mechanical parts, the control and drive electronics, and the application software) for performing such observations is also described

Touchless attitude correction for satellite with constant magnetic moment

Science.gov (United States)

Ao, Hou-jun; Yang, Le-ping; Zhu, Yan-wei; Zhang, Yuan-wen; Huang, Huan

2017-09-01

Rescue of satellite with attitude fault is of great value. Satellite with improper injection attitude may lose contact with ground as the antenna points to the wrong direction, or encounter energy problems as solar arrays are not facing the sun. Improper uploaded command may set the attitude out of control, exemplified by Japanese Hitomi spacecraft. In engineering practice, traditional physical contact approaches have been applied, yet with a potential risk of collision and a lack of versatility since the mechanical systems are mission-specific. This paper puts forward a touchless attitude correction approach, in which three satellites are considered, one having constant dipole and two having magnetic coils to control attitude of the first. Particular correction configurations are designed and analyzed to maintain the target's orbit during the attitude correction process. A reference coordinate system is introduced to simplify the control process and avoid the singular value problem of Euler angles. Based on the spherical triangle basic relations, the accurate varying geomagnetic field is considered in the attitude dynamic mode. Sliding mode control method is utilized to design the correction law. Finally, numerical simulation is conducted to verify the theoretical derivation. It can be safely concluded that the no-contact attitude correction approach for the satellite with uniaxial constant magnetic moment is feasible and potentially applicable to on-orbit operations.

LEOPACK The integrated services communications system based on LEO satellites

Science.gov (United States)

Negoda, A.; Bunin, S.; Bushuev, E.; Dranovsky, V.

LEOPACK is yet another LEO satellite project which provides global integrated services for 'business' communications. It utilizes packet rather then circuit switching in both terrestrial and satellite chains as well as cellular approach for frequencies use. Original multiple access protocols and decentralized network control make it possible to organize regionally or logically independent and world-wide networks. Relatively small number of satellites (28) provides virtually global network coverage.

Effects of satellite transmitters on captive and wild mallards

Science.gov (United States)

Kesler, Dylan C.; Raedeke, Andrew H.; Foggia, Jennifer R.; Beatty, William S.; Webb, Elisabeth B.; Humburg, Dale D.; Naylor, Luke W.

2014-01-01

Satellite telemetry has become a leading method for studying large-scale movements and survival in birds, yet few have addressed potential effects of the larger and heavier tracking equipment on study subjects. We simultaneously evaluated effects of satellite telemetry equipment on captive and wild mallards (Anas platyrhynchos) to assess impacts on behavior, body mass, and movement. We randomly assigned 55 captive ducks to one of 3 treatment groups, including a standard body harness group, a modified harness group, and a control group. Ducks in the control group were not fitted with equipment, whereas individuals in the other 2 groups were fitted with dummy transmitters attached with a Teflon ribbon harness or with a similar harness constructed of nylon cord. At the conclusion of the 14-week captive study, mean body mass of birds in the control group was 40–105 g (95% CI) greater than birds with standard harnesses, and 28–99 g (95% CI) greater than birds with modified harnesses. Further, results of focal behavior observations indicated ducks with transmitters were less likely to be in water than control birds. We also tested whether movements of wild birds marked with a similar Teflon harness satellite transmitter aligned with population movements reported by on-the-ground observers who indexed local abundances of mid-continent mallards throughout the non-breeding period. Results indicated birds marked with satellite transmitters moved concurrently with the larger unmarked population. Our results have broad implications for field research and suggest that investigators should consider potential for physiological and behavioral effects brought about by tracking equipment. Nonetheless, results from wild ducks indicate satellite telemetry has the potential to provide useful movement data.

Compensation of an attitude disturbance torque caused by magnetic substances in LEO satellites

Science.gov (United States)

Inamori, Takaya; Wang, Jihe; Saisutjarit, Phongsatorn; Ohsaki, Hiroyuki

This research considers an attitude disturbance torque caused by ferromagnetic substances in a LEO satellite. In most LEO satellite missions, a gravity gradient torque, solar pressure torque, aerodynamic torque, and magnetic dipole moment torque are considered for their attitude control systems, however, the effect of the ferromagnetic substances causing a disturbance torque in the geomagnetic field is not considered in previous satellite missions. The ferromagnetic substances such as iron cores of MTQs and a magnetic hysteresis damper for a passive attitude control system are used in various small satellites. These substances cause a disturbance torque which is almost the same magnitude of the dipole magnetic disturbance and the dominant disturbance in the worst cases. This research proposes a method to estimate and compensate for the effect of the ferromagnetic substances using an extended Kalman filter. From simulation results, the research concludes that the proposed method is useful and attractive for precise attitude control for LEO satellite missions.

High Bandwidth Optical Links for Micro-Satellite Support

Science.gov (United States)

Chao, Tien-Hsin (Inventor); Wilson, Keith E. (Inventor); Coste, Keith (Inventor)

2016-01-01

A method, systems, apparatus and device enable high bandwidth satellite communications. An onboard tracking detector, installed in a low-earth orbit satellite, detects a position of an incoming optical beam received/transmitted from a first ground station of one or more ground stations. Tracker electronics determine orientation information of the incoming optical beam based on the position. Control electronics receive the orientation information from the tracker electronics, and control a waveguide drive electronics. The waveguide drive electronics control a voltage that is provided to an electro-optic waveguide beam steering device. The electro-optic waveguide beam steering device steers an outgoing optical beam to one of the one or more ground stations based on the voltage.

The Use of a Satellite Communications System for Command and Control of the National Aeronautics and Space Administration Surrogate Unmanned Aerial System Research Aircraft

Science.gov (United States)

Howell, Charles T.; Jones, Frank; Hutchinson, Brian; Joyce, Claude; Nelson, Skip; Melum, Mike

2017-01-01

The NASA Langley Research Center has transformed a Cirrus Design SR22 general aviation (GA) aircraft into an Unmanned Aerial Systems (UAS) Surrogate research aircraft which has served for several years as a platform for unmanned systems research and development. The aircraft is manned with a Safety Pilot and a Research Systems Operator (RSO) that allows for flight operations almost any-where in the national airspace system (NAS) without the need for a Federal Aviation Administration (FAA) Certificate of Authorization (COA). The UAS Surrogate can be remotely controlled from a modular, transportable ground control station (GCS) like a true UAS. Ground control of the aircraft is accomplished by the use of data links that allow the two-way passage of the required data to control the aircraft and provide the GCS with situational awareness. The original UAS Surrogate data-link system was composed of redundant very high frequency (VHF) data radio modems with a maximum range of approximately 40 nautical miles. A new requirement was developed to extend this range beyond visual range (BVR). This new requirement led to the development of a satellite communications system that provided the means to command and control the UAS Surrogate at ranges beyond the limits of the VHF data links. The system makes use of the Globalstar low earth orbit (LEO) satellite communications system. This paper will provide details of the development, implementation, and flight testing of the satellite data communications system on the UAS Surrogate research aircraft.

Future control room design (modernization of control room systems); Zukuenftiges Wartendesign (Modernisierung von Warteneinrichtungen)

Energy Technology Data Exchange (ETDEWEB)

Reischl, Ludwig; Freitag, Timo; Dergel, Rene [AREVA NP (Germany). NLLR-G ' ' Reactor I and C' '

2009-07-01

In the frame of lifetime extension for nuclear power plants the modernization of the complete safety and operational control technology will be digitalized. It is also recommended to modernize the operator facilities, monitoring systems in the control room, the back-up shut-down center and the local control stations. The authors summarize the reasons for the modernization recommendations and discuss possible solutions for display-oriented control rooms. A concept for control room backfitting includes generic requirements, requirements of the local authorities, ergonomic principles information content and information density, and the design process. The backfitting strategy should include a cooperation with the operational personnel, The quality assurance and training via simulator needs sufficient timing during the implementation of the backfitting.

Isolation contactor state control system

Energy Technology Data Exchange (ETDEWEB)

Bissontz, Jay E.

2017-05-16

A controller area network (CAN) installed on a hybrid electric vehicle provides one node with control of high voltage power distribution system isolation contactors and the capacity to energize a secondary electro-mechanical relay device. The output of the secondary relay provides a redundant and persistent backup signal to the output of the node. The secondary relay is relatively immune to CAN message traffic interruptions and, as a result, the high voltage isolation contactor(s) are less likely to transition open in the event that the intelligent output driver should fail.

European Telecommunications Satellite II (EUTELSAT II)

Science.gov (United States)

Laemmel, G.; Brittinger, P.

1991-01-01

EUTELSAT II is a regional public telecommunications system for Europe. The services which will be provided are telephone and television. The satellites will be placed at a geostationary orbit within the arcs of 6 degrees east to 19 degrees east or 26 degrees to 36 degrees east. The designed lifetime is 7 years. After separation of the satellites from the launch vehicles, telemetry, telecommand, and ranging will be performed within the S-band frequencies. After positioning of the satellite at its final geostationary orbit, the Ku-band telecommunication equipment will be activated. From this time on, all satellite control operations will be performed in Ku-band. The Deep Space Network (DSN) will support the transfer and drift orbit mission phases. The coverage will consist of the 26-m antennas at Goldstone and Canberra as prime support for the transfer and drift orbits. Maximum support will consist of a 7-day period, plus 14 days of contingency support. Information is given in tabular form for DSN support, frequency assignments, telemetry, command, and tracking support responsibility.

Non-exclusive satellite power system

Energy Technology Data Exchange (ETDEWEB)

Drummond, J.E. (Power Conversion Technology, Inc., San Diego, Calif.); Cowhey, P.F. (California, University, La Jolla, Calif.)

1980-09-01

A modification of the satellite solar power system employing smaller satellites that are not stationary but move in circular or elliptical orbits of two or three hour periods is discussed. The orbits could be inclined at plus or minus 63.4 deg, 73.1 deg, or 14.3 deg to the equatorial plane. This Interregional or Isoinsolation Power System (IPS) greatly reduces the mass and cost of the antenna needed in the sky and the area required for the rectenna and safety region on the ground (the product of the areas of the antennas and rectennas of the IPS system being between 10 and 20 times lower than that required in the conventional SPS system). International control of IPS through a Solar Satellite Consortium (Solsat) is advocated, patterned after the successful Intelsat consortium, and it is stressed that the system must not be allowed to acquire a military capacity. It is emphasized that the smaller rectennas would not destabilize the ionosphere.

Satellite communications: possibilities and problems

International Nuclear Information System (INIS)

Hine, M.

1986-01-01

Communication links via satellites are becoming available in Europe, both as part of the development of the telephone system and as special services aimed at data traffic. They offer the possibility of speeds between 50 kb/s and 2 Mb/s, without the problems and long term commitments of long distance land lines. Such links are provided by the PTT's as circuits which can be booked for variable periods, and have error rates which can be very low and well controlled. Problems in networking can arise from the satellite delay, particularly if errors occur in the local connections, and from the leased circuit and tariff philosophies of the PTT's. (Auth.)

Leveraging the NPS Femto Satellite for Alternative Satellite Communication Networks

Science.gov (United States)

2017-09-01

programmed for eventual integration with the Iridium Network , which is then tested. C. THESIS ORGANIZATION The thesis addresses these questions...NPS FEMTO SATELLITE FOR ALTERNATIVE SATELLITE COMMUNICATION NETWORKS by Faisal S. Alshaya September 2017 Co-Advisors: Steven J. Iatrou...TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE LEVERAGING THE NPS FEMTO SATELLITE FOR ALTERNATIVE SATELLITE COMMUNICATION NETWORKS 5

Meteorological satellite systems

CERN Document Server

Tan, Su-Yin

2014-01-01

“Meteorological Satellite Systems” is a primer on weather satellites and their Earth applications. This book reviews historic developments and recent technological advancements in GEO and polar orbiting meteorological satellites. It explores the evolution of these remote sensing technologies and their capabilities to monitor short- and long-term changes in weather patterns in response to climate change. Satellites developed by various countries, such as U.S. meteorological satellites, EUMETSAT, and Russian, Chinese, Japanese and Indian satellite platforms are reviewed. This book also discusses international efforts to coordinate meteorological remote sensing data collection and sharing. This title provides a ready and quick reference for information about meteorological satellites. It serves as a useful tool for a broad audience that includes students, academics, private consultants, engineers, scientists, and teachers.

Uniform Distance Scaling Behavior of Planet-Satellite Nanostructures Made by Star Polymers.

Science.gov (United States)

Rossner, Christian; Tang, Qiyun; Glatter, Otto; Müller, Marcus; Vana, Philipp

2017-02-28

Planet-satellite nanostructures from RAFT star polymers and larger (planet) as well as smaller (satellite) gold nanoparticles are analyzed in experiments and computer simulations regarding the influence of arm number of star polymers. A uniform scaling behavior of planet-satellite distances as a function of arm length was found both in the dried state (via transmission electron microscopy) after casting the nanostructures on surfaces and in the colloidally dispersed state (via simulations and small-angle X-ray scattering) when 2-, 3-, and 6-arm star polymers were employed. This indicates that the planet-satellite distances are mainly determined by the arm length of star polymers. The observed discrepancy between TEM and simulated distances can be attributed to the difference of polymer configurations in dried and dispersed state. Our results also show that these distances are controlled by the density of star polymers end groups, and the number of grabbed satellite particles is determined by the magnitude of the corresponding density. These findings demonstrate the feasibility to precisely control the planet-satellite structures at the nanoscale.

Boomerang Satellites

Science.gov (United States)

Hesselbrock, Andrew; Minton, David A.

2017-10-01

We recently reported that the orbital architecture of the Martian environment allows for material in orbit around the planet to ``cycle'' between orbiting the planet as a ring, or as coherent satellites. Here we generalize our previous analysis to examine several factors that determine whether satellites accreting at the edge of planetary rings will cycle. In order for the orbiting material to cycle, tidal evolution must decrease the semi-major axis of any accreting satellites. In some systems, the density of the ring/satellite material, the surface mass density of the ring, the tidal parameters of the system, and the rotation rate of the primary body contribute to a competition between resonant ring torques and tidal dissipation that prevent this from occurring, either permanently or temporarily. Analyzing these criteria, we examine various bodies in our solar system (such as Saturn, Uranus, and Eris) to identify systems where cycling may occur. We find that a ring-satellite cycle may give rise to the current Uranian ring-satellite system, and suggest that Miranda may have formed from an early, more massive Uranian ring.

Water experiments on thermal striping in reactor vessel of advanced sodium-cooled fast reactor. Influence of flow collector of backup CR guide tube

International Nuclear Information System (INIS)

Kobayashi, Jun; Ezure, Toshiki; Tanaka, Masaaki; Kamide, Hideki

2016-01-01

Design study of an advanced large-scale sodium-cooled fast reactor (SFR) has been conducted in JAEA. In the region between the bottom of the Upper Internal Structure (UIS) and the core outlet, the hot sodium from the fuel subassembly mixes with the cold sodium from the neighbor control rod (CR) channel. Therefore, temperature fluctuation due to mixing fluids at different temperatures may cause high cycle thermal fatigue at the bottom of the UIS. In the advanced design, installation of a flow guide structure named Flow-Collector (FC) to the backup control rod (BCR) guide tube is considered to enhance reliable operation of self-actuated shutdown system (SASS) and to ensure reactor shutdown operation. Previously, water experiments without the FC model had been examined in JAEA to investigate effective countermeasures to the significant temperature fluctuation generation at the bottom of the UIS. Since the FC may affect the thermal mixing behavior at the bottom of the UIS, influence of the FC on characteristics of the temperature fluctuation around the BCR channels was investigated using a water experimental facility with structure model of the FC. Through the experiment, small influence of the FC on the temperature fluctuation distribution at the bottom of the UIS was indicated. (author)

Visual attitude propagation for small satellites

Science.gov (United States)

Rawashdeh, Samir A.

As electronics become smaller and more capable, it has become possible to conduct meaningful and sophisticated satellite missions in a small form factor. However, the capability of small satellites and the range of possible applications are limited by the capabilities of several technologies, including attitude determination and control systems. This dissertation evaluates the use of image-based visual attitude propagation as a compliment or alternative to other attitude determination technologies that are suitable for miniature satellites. The concept lies in using miniature cameras to track image features across frames and extracting the underlying rotation. The problem of visual attitude propagation as a small satellite attitude determination system is addressed from several aspects: related work, algorithm design, hardware and performance evaluation, possible applications, and on-orbit experimentation. These areas of consideration reflect the organization of this dissertation. A "stellar gyroscope" is developed, which is a visual star-based attitude propagator that uses relative motion of stars in an imager's field of view to infer the attitude changes. The device generates spacecraft relative attitude estimates in three degrees of freedom. Algorithms to perform the star detection, correspondence, and attitude propagation are presented. The Random Sample Consensus (RANSAC) approach is applied to the correspondence problem to successfully pair stars across frames while mitigating falsepositive and false-negative star detections. This approach provides tolerance to the noise levels expected in using miniature optics and no baffling, and the noise caused by radiation dose on orbit. The hardware design and algorithms are validated using test images of the night sky. The application of the stellar gyroscope as part of a CubeSat attitude determination and control system is described. The stellar gyroscope is used to augment a MEMS gyroscope attitude propagation

Recent Korean R&D in Satellite Communications

Science.gov (United States)

Lee, Ho-Jin; Kim, Jae Moung; Lee, Byung-Seub; Lee, Han; Ryoo, Jang-Soo

The R&D in satellite communications in Korea has been driven mainly by KCC (Korea Communications Commission) but in a small scale compared to Korea space development program organized by MEST (Ministry of Education, Science and Technology). Public and civilian satcom sector R&D has been led mainly by ETRI with small/medium companies contrary to rare investment in private sector while military sector R&D has been orchestrated by ADD with defense industry. By the COMS (Communication, Ocean and Meteorological Satellite) experimental Ka-band payload, Korea pursues a space qualification of own technology for national infrastructure evolution as well as industrialization of space R&D results. Once COMS launched and space qualified in 2009, subsequent application experiments and new technology R&D like UHDTV will entail service and industry promotion. The payload technology is expected for the next Korean commercial satellites or for new OBP satellites. The COMS ground control system and GNSS ground station technologies are under development for COMS operation and enhanced GNSS services along with advent of Galileo respectively. Satellite broadband mobile VSAT based on DVB-S2/RCS (+M) and low profile tracking antennas have been developed for trains, ships, and planes. While APSI is developing GMR-1 based Thuraya handset functions, ETRI is designing IMT-Advanced satellite radio interface for satellite and terrestrial dual-mode handheld communication system like Japanese STICS, with universities' satellite OFDM researches. A 21GHz Ka-band higher-availability scalable HD broadcasting technology and SkyLife's hybrid satellite IPTV technology are being developed. In near term Korea will extend R&D programs to upgrade the space communication infrastructure for universal access to digital opportunity and safer daily life from disaster, and to promote space green IT industrialization, national security, and space resources sovereign. Japanese stakeholders are invited to establish

Multi-agent robotic systems and applications for satellite missions

Science.gov (United States)

Nunes, Miguel A.

A revolution in the space sector is happening. It is expected that in the next decade there will be more satellites launched than in the previous sixty years of space exploration. Major challenges are associated with this growth of space assets such as the autonomy and management of large groups of satellites, in particular with small satellites. There are two main objectives for this work. First, a flexible and distributed software architecture is presented to expand the possibilities of spacecraft autonomy and in particular autonomous motion in attitude and position. The approach taken is based on the concept of distributed software agents, also referred to as multi-agent robotic system. Agents are defined as software programs that are social, reactive and proactive to autonomously maximize the chances of achieving the set goals. Part of the work is to demonstrate that a multi-agent robotic system is a feasible approach for different problems of autonomy such as satellite attitude determination and control and autonomous rendezvous and docking. The second main objective is to develop a method to optimize multi-satellite configurations in space, also known as satellite constellations. This automated method generates new optimal mega-constellations designs for Earth observations and fast revisit times on large ground areas. The optimal satellite constellation can be used by researchers as the baseline for new missions. The first contribution of this work is the development of a new multi-agent robotic system for distributing the attitude determination and control subsystem for HiakaSat. The multi-agent robotic system is implemented and tested on the satellite hardware-in-the-loop testbed that simulates a representative space environment. The results show that the newly proposed system for this particular case achieves an equivalent control performance when compared to the monolithic implementation. In terms on computational efficiency it is found that the multi

Requirements and design structure for Surya Satellite-1

Science.gov (United States)

Steven, H.; Huzain, M. F.

2018-05-01

Currently, there are various references on the manufacture of nanosatellite specifications weighing 1KG - 10KG.The Surya Satellite-1 is the first nanosatellite made by universities in Indonesia. The Surya Satellite-1 team gets a launch offer from Japan Aerospace Exploration Agency (JAXA) and, all the nanosatellites manufacturer racers at ICD (Interface Control Document) obtained from JAXA. The formation of the Satellite-1 Surya framework is also based on the provisions of JAXA. The various specifications and requirements specified by the JAXA space agency consisting of specific specifications such as the mass of nanosatellite 1U (10cm x 10cm x 11.65cm) size of at least 0.13KG and a maximum of 1.33KG, with the determination of a gravity point not exceeding 2 cm from the nanosatellite geometry center point. In the case of preventing solar radiation in space, there is a requirement that the structure of satellite structures on hard black anodization should be more than 10 meters in the surface of the satellite structure. In terms of detail, the satellite structure is a black hard anodized aluminum after its manufacturing process derived from the MIL-A-8625 document, type 3.

Satellite broadcasting - The European experience and perspective

Science.gov (United States)

Watson, Alan

1991-11-01

The use of satellites is considered as a means for developing a European transnational broadcasting system with attention given to the control of technology. A tension is described between maintaining technology as the property of one nation when the DBSs are developed for multinational program broadcasting. The simultaneous development of satellite systems is theorized to lead eventually to a single merged program for a particular nation, and the effect is considered of the regulation of cross-holding and cross-selling systems by investors.

Network design consideration of a satellite-based mobile communications system

Science.gov (United States)

Yan, T.-Y.

1986-01-01

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

Protein Availability and Satellite Cell Dynamics in Skeletal Muscle.

Science.gov (United States)

Shamim, Baubak; Hawley, John A; Camera, Donny M

2018-06-01

Human skeletal muscle satellite cells are activated in response to both resistance and endurance exercise. It was initially proposed that satellite cell proliferation and differentiation were only required to support resistance exercise-induced hypertrophy. However, satellite cells may also play a role in muscle fibre remodelling after endurance-based exercise and extracellular matrix regulation. Given the importance of dietary protein, particularly branched chain amino acids, in supporting myofibrillar and mitochondrial adaptations to both resistance and endurance-based training, a greater understanding of how protein intake impacts satellite cell activity would provide further insight into the mechanisms governing skeletal muscle remodelling with exercise. While many studies have investigated the capacity for protein ingestion to increase post-exercise rates of muscle protein synthesis, few investigations have examined the role for protein ingestion to modulate satellite cell activity. Here we review the molecular mechanisms controlling the activation of satellite cells in response to mechanical stress and protein intake in both in vitro and in vivo models. We provide a mechanistic framework that describes how protein ingestion may enhance satellite activity and promote exercise adaptations in human skeletal muscle.

Sun and planet detection system for satellites. Sonnen- und Erderfassungsverfahren fuer Satelliten

Energy Technology Data Exchange (ETDEWEB)

Lange, B O; Scheit, A

1980-05-22

The invention refers to a process for the sun and planet detection system for satellites stabilised in three axes and equipped with detection sensors. The purpose of the invention is to describe such a detection system, which makes quick and reliable guiding of the satellite to its final position possible, permits the use of sensors of simple construction and of simple control laws and simple control logic. According to the invention, this problem is solved by having cumulative or alternate steps, depending on the position of the satellite relative to the sun. According to the invention they refer to the position of the sun outside the field of view for the measurement of various components and the simultaneous availability of several component values. It is particularly advantageous if only the absolutely necessary satellite manoeuvres have to be carried out, as this saves fuel and makes it possible to increase the payload or extend the satellite's life. (HWJ).

Centriolar satellites

DEFF Research Database (Denmark)

Tollenaere, Maxim A X; Mailand, Niels; Bekker-Jensen, Simon

2015-01-01

Centriolar satellites are small, microscopically visible granules that cluster around centrosomes. These structures, which contain numerous proteins directly involved in centrosome maintenance, ciliogenesis, and neurogenesis, have traditionally been viewed as vehicles for protein trafficking...... highlight newly discovered regulatory mechanisms targeting centriolar satellites and their functional status, and we discuss how defects in centriolar satellite components are intimately linked to a wide spectrum of human diseases....

Knee-clicks and visual traits indicate fighting ability in eland antelopes: multiple messages and back-up signals

DEFF Research Database (Denmark)

Bro-Jørgensen, Jakob; Dabelsteen, Torben

2008-01-01

frequency of the knee-clicking sound honestly indicated body size, a main determinant of fighting ability. In contrast, the dewlap size increased with estimated age rather than body size, suggesting that, by magnifying the silhouette of older bulls disproportionately, the dewlap acts as an indicator of age......Background: Given the costs of signalling, why do males often advertise their fighting ability to rivals using several signals rather than just one? Multiple signalling theories have developed largely in studies of sexual signals, and less is known about their applicability to intra-sexual...... agonistic signals in eland reflect three separate components of fighting ability: (1) body size, (2) age and (3) presumably androgen-related aggression, which is reflected in three backup signals. The study highlights how complex agonistic signalling systems can evolve through the simultaneous action...

Utilization of control rod drive (CRD) system for long term core cooling

International Nuclear Information System (INIS)

Huerta B, A.

1991-01-01

In this paper we consider an application of Probabilistic Risk Assessment (PRA) to risk management. Foreseeable risk management strategies to prevent core damage are constrained by the availability of first line systems as well as support systems. The actual trend in the evaluation of risk management options can be performed in a number of ways. An example is the identification of back-up systems which could be used to perform the same safety functions. In this work we deal with the evaluation of the feasibility, for BWR's, to use the Control Rod Drive system to maintain an adequate reactor core long term cooling in some accident sequences. This preliminary evaluation is carried out as a part of the Internal Events Analysis for Laguna Verde Nuclear Power Plant (LVNPP) that is currently under way by the Mexican Nuclear Regulatory Body. This analysis addresses the evaluation and incorporation of all the systems, including the safety related and the back-up non safety related systems, that are available for the operator in order to prevent core damage. As a part of this analysis the containment venting capability is also evaluated as a back-up of the containment heat removal function. This will prevent the primary containment overpressurization and loss of certain core cooling systems. A selection of accident sequences in which the Control Rod Drive system could be used to mitigate the accident and prevent core damage are discussed. A personal computer transient analysis code is used to carry out thermohydraulic simulations in order to evaluate the Control Rod Drive system performance, the corresponding results are presented. Finally, some preliminary conclusions are drawn. (author). 9 refs, 5 figs

Satellite end of life constraints: Technical and organisational solutions

Science.gov (United States)

Cabrières, Bernard; Alby, Fernand; Cazaux, Christian

2012-04-01

Since 1974 with the radiocommunication satellite Symphony1, CNES launched and operated 11 GEO and 20 LEO satellites. During those 36 years, both flight segment and ground segment dramatically evolved and operational organisations and techniques equally improved. At the present time, CNES operates 1 GEO satellite and 17 LEO satellites with not much more people and costs than in 1986 when its first Satellite Operation Direction in Toulouse was only in charge of Telecom1A, Telecom1B and Spot1. This fantastic technical evolution combined with the huge increase of services to citizens and governments given by Space systems was unfortunately also associated with an enormous growth of space pollution by debris of all sizes. From the beginning, CNES was a major actor of the international effort to promote regulations in order to try to reduce or at least control this problematic situation. Internally, CNES, not only set up an operational on-call service to deal with collision risks, but decided to do its best to apply the new guidelines to the end of life of satellites under its responsibility even for those developed and launched a very long time ago. For instance, that was the case in 2009 for the reorbitation of the GEO satellite Telecom 2C (launched in 1995) and for the deorbitation of the LEO satellite Spot2 (launched in 1990). In addition, CNES prepares procedures to be able to be as exemplary as possible for its other spacecrafts whose end of life approaches. The constraints and challenges to face in order to cope with these new requirements are multiple: choice of final orbit, realistic calculation of re-entry duration, estimation of residual propellant, electric passivation, management of explosion risks… All these studies and operational experience gained will be helpful for the new role of CNES, which recently became in charge of controlling space operators in the frame of the new French space law on space operations.

EFFECTS OF VOLUNTARY WHEEL RUNNING ON SATELLITE CELLS IN THE RAT PLANTARIS MUSCLE

Directory of Open Access Journals (Sweden)

Atsushi Kojima

2009-03-01

Full Text Available This study investigated the effects of voluntary wheel running on satellite cells in the rat plantaris muscle. Seventeen 5-week-old male Wistar rats were assigned to a control (n = 5 or training (n = 12 group. Each rat in the training group ran voluntarily in a running-wheel cage for 8 weeks. After the training period, the animals were anesthetized, and the plantaris muscles were removed, weighed, and analyzed immunohistochemically and biochemically. Although there were no significant differences in muscle weight or fiber area between the groups, the numbers of satellite cells and myonuclei per muscle fiber, percentage of satellite cells, and citrate synthase activity were significantly higher in the training group compared with the control group (p < 0.05. The percentage of satellite cells was also positively correlated with distance run in the training group (r = 0.61, p < 0.05. Voluntary running can induce an increase in the number of satellite cells without changing the mean fiber area in the rat plantaris muscle; this increase in satellite cell content is a function of distance run

Development of the European Small Geostationary Satellite SGEO

Science.gov (United States)

Lübberstedt, H.; Schneider, A.; Schuff, H.; Miesner, Th.; Winkler, A.

2008-08-01

The SGEO product portfolio, ranging from Satellite platform delivery up to in-orbit delivery of a turnkey system including satellite and ground control station, is designed for applications ranging from TV Broadcast to multimedia applications, Internet access, mobile or fixed services in a wide range of frequency bands. Furthermore, Data Relay missions such as the European Data Relay Satellite (EDRS) as well as other institutional missions are targeted. Key design features of the SGEO platform are high flexibility and modularity in order to accommodate a very wide range of future missions, a short development time below two years and the objective to build the system based on ITAR free subsystems and components. The system will provide a long lifetime of up to 15 years in orbit operations with high reliability. SGEO is the first European satellite to perform all orbit control tasks solely by electrical propulsion (EP). This design provides high mass efficiency and the capability for direct injection into geostationary orbit without chemical propulsion (CP). Optionally, an Apogee Engine Module based on CP will provide the perigee raising manoeuvres in case of a launch into geostationary transfer orbit (GTO). This approach allows an ideal choice out of a wide range of launcher candidates in dependence of the required payload capacity. SGEO will offer to the market a versatile and high performance satellite system with low investment risk for the customer and a short development time. This paper provides an overview of the SGEO system key features and the current status of the SGEO programme.

The German joint research project "concepts for future gravity satellite missions"

Science.gov (United States)

Reubelt, Tilo; Sneeuw, Nico; Fichter, Walter; Müller, Jürgen

2010-05-01

Within the German joint research project "concepts for future gravity satellite missions", funded by the Geotechnologies programme of the German Federal Ministry of Education and Research, options and concepts for future satellite missions for precise (time-variable) gravity field recovery are investigated. The project team is composed of members from science and industry, bringing together experts in geodesy, satellite systems, metrology, sensor technology and control systems. The majority of team members already contributed to former gravity missions. The composition of the team guarantees that not only geodetic aspects and objectives are investigated, but also technological and financial constraints are considered. Conversely, satellite, sensor and system concepts are developed and improved in a direct exchange with geodetic and scientific claims. The project aims to develop concepts for both near and mid-term future satellite missions, taking into account e.g. advanced satellite formations and constellations, improved orbit design, innovative metrology and sensor systems and advances in satellite systems.

Development of Mission and Spacecraft Dynamics Analysis System for Geostationary Communication Satellite

Directory of Open Access Journals (Sweden)

Hyeon Cheol Gong

1998-06-01

Full Text Available We consider the motion of the subsystems as separate bodies as well as the entire satellite for the attitude and orbit control of a communication satellite by multi-body modeling technique. Thus, the system can be applied to a general communication satellite as well as a specific communication satellite, i.e. Koreasat I, II. The simulation results can be viewed by two-dimensional graphics and three-dimensional animation. The graphical user interface (GUI makes its usage much simpler. We have simulated a couple of scenarios for Koreasat I, II which are being operated as geostationary communication satellites to verify the system performance.

Tethered Satellite System Contingency Investigation Board

Science.gov (United States)

1992-11-01

The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether

A research on the application of software defined networking in satellite network architecture

Science.gov (United States)

Song, Huan; Chen, Jinqiang; Cao, Suzhi; Cui, Dandan; Li, Tong; Su, Yuxing

2017-10-01

Software defined network is a new type of network architecture, which decouples control plane and data plane of traditional network, has the feature of flexible configurations and is a direction of the next generation terrestrial Internet development. Satellite network is an important part of the space-ground integrated information network, while the traditional satellite network has the disadvantages of difficult network topology maintenance and slow configuration. The application of SDN technology in satellite network can solve these problems that traditional satellite network faces. At present, the research on the application of SDN technology in satellite network is still in the stage of preliminary study. In this paper, we start with introducing the SDN technology and satellite network architecture. Then we mainly introduce software defined satellite network architecture, as well as the comparison of different software defined satellite network architecture and satellite network virtualization. Finally, the present research status and development trend of SDN technology in satellite network are analyzed.

Dynamic Modeling and Simulation of Marine Satellite Tracking Antenna Using Lagrange Method

DEFF Research Database (Denmark)

Wang, Yunlong; Soltani, Mohsen; Hussain, Dil muhammed Akbar

2016-01-01

Marine Satellite Tracking Antenna (MSTA) is a necessary device in ships for receiving satellite signals when they are sailing on the sea. This paper presents a simple methodology to obtain the dynamic equations of MSTA through Lagrange method, which is fundamental in design of modelbased controll......Marine Satellite Tracking Antenna (MSTA) is a necessary device in ships for receiving satellite signals when they are sailing on the sea. This paper presents a simple methodology to obtain the dynamic equations of MSTA through Lagrange method, which is fundamental in design of modelbased...

Satellite Application for Disaster Management Information Systems

Science.gov (United States)

Okpanachi, George

Abstract Satellites are becoming increasingly vital to modern day disaster management activities. Earth observation (EO) satellites provide images at various wavelengths that assist rapid-mapping in all phases of the disaster management cycle: mitigation of potential risks in a given area, preparedness for eventual disasters, immediate response to a disaster event, and the recovery/reconstruction efforts follo wing it. Global navigation satellite systems (GNSS) such as the Global Positioning System (GPS) assist all the phases by providing precise location and navigation data, helping manage land and infrastructures, and aiding rescue crews coordinate their search efforts. Effective disaster management is a complex problem, because it involves many parameters, which are usually not easy to measure and even identify: Analysis of current situation, planning, optimum resource management, coordination, controlling and monitoring current activities and making quick and correct decisions are only some of these parameters, whose complete list is very long. Disaster management information systems (DMIS) assist disaster management to analyse the situation better, make decisions and suggest further actions following the emergency plans. This requires not only fast and thorough processing and optimization abilities, but also real-time data provided to the DMIS. The need of DMIS for disaster’s real-time data can be satisfied by small satellites data utilization. Small satellites can provide up-to-data, plus a better media to transfer data. This paper suggests a rationale and a framework for utilization of small Satellite data by DMIS. DMIS should be used ‘’before’’, ‘’during’’ and ‘’after’’ the disasters. Data provided by the Small Satellites are almost crucial in any period of the disasters, because early warning can save lives, and satellite data may help to identify disasters before they occur. The paper also presents’ ‘when’’, �

Communication satellite applications

Science.gov (United States)

Pelton, Joseph N.

The status and future of the technologies, numbers and services provided by communications satellites worldwide are explored. The evolution of Intelsat satellites and the associated earth terminals toward high-rate all-digital telephony, data, facsimile, videophone, videoconferencing and DBS capabilities are described. The capabilities, services and usage of the Intersputnik, Eutelsat, Arabsat and Palapa systems are also outlined. Domestic satellite communications by means of the Molniya, ANIK, Olympus, Intelsat and Palapa spacecraft are outlined, noting the fast growth of the market and the growing number of different satellite manufacturers. The technical, economic and service definition issues surrounding DBS systems are discussed, along with presently operating and planned maritime and aeronautical communications and positioning systems. Features of search and rescue and tracking, data, and relay satellite systems are summarized, and services offered or which will be offered by every existing or planned communication satellite worldwide are tabulated.

China: Possible Missile Technology Transfers from U.S. Satellite Export Policy - Actions and Chronology

National Research Council Canada - National Science Library

Kan, Shirley A

2001-01-01

.... Some critics opposed satellite exports to China, while others were concerned that the Clinton Administration relaxed export controls and monitoring of commercial satellites in moving the licensing...

Flight Test of a Propulsion-Based Emergency Control System on the MD-11 Airplane with Emphasis on the Lateral Axis

Science.gov (United States)

Burken, John J.; Burcham, Frank W., Jr.; Maine, Trindel A.; Feather, John; Goldthorpe, Steven; Kahler, Jeffrey A.

1996-01-01

A large, civilian, multi-engine transport MD-11 airplane control system was recently modified to perform as an emergency backup controller using engine thrust only. The emergency backup system, referred to as the propulsion-controlled aircraft (PCA) system, would be used if a major primary flight control system fails. To allow for longitudinal and lateral-directional control, the PCA system requires at least two engines and is implemented through software modifications. A flight-test program was conducted to evaluate the PCA system high-altitude flying characteristics and to demonstrate its capacity to perform safe landings. The cruise flight conditions, several low approaches and one landing without any aerodynamic flight control surface movement, were demonstrated. This paper presents results that show satisfactory performance of the PCA system in the longitudinal axis. Test results indicate that the lateral-directional axis of the system performed well at high attitude but was sluggish and prone to thermal upsets during landing approaches. Flight-test experiences and test techniques are also discussed with emphasis on the lateral-directional axis because of the difficulties encountered in flight test.

Validation of an Innovative Satellite-Based UV Dosimeter

Science.gov (United States)

Morelli, Marco; Masini, Andrea; Simeone, Emilio; Khazova, Marina

2016-08-01

We present an innovative satellite-based UV (ultraviolet) radiation dosimeter with a mobile app interface that has been validated by exploiting both ground-based measurements and an in-vivo assessment of the erythemal effects on some volunteers having a controlled exposure to solar radiation.Both validations showed that the satellite-based UV dosimeter has a good accuracy and reliability needed for health-related applications.The app with this satellite-based UV dosimeter also includes other related functionalities such as the provision of safe sun exposure time updated in real-time and end exposure visual/sound alert. This app will be launched on the global market by siHealth Ltd in May 2016 under the name of "HappySun" and available both for Android and for iOS devices (more info on http://www.happysun.co.uk).Extensive R&D activities are on-going for further improvement of the satellite-based UV dosimeter's accuracy.

Epigenetic reprogramming of pericentromeric satellite DNA in premalignant and malignant lesions

DEFF Research Database (Denmark)

Brückmann, Nadine Heidi; Pedersen, Christina Bøg; Ditzel, Henrik Jørn

2018-01-01

on pericentromeric satellites in primary melanocytes. This suggests that polycomb bodies form in cancer cells with global DNA demethylation to control the stability of pericentromeric satellite DNA. These results reveal a novel epigenetic perturbation specific to premalignant and malignant cells thatmaybe used...... as an early diagnostic marker for detection of precancerous changes and a new therapeutic entry point. Implications: Pericentromeric satellite DNA is epigenetically reprogrammed into polycomb bodies as a premalignant event with implications for transcriptional activity and genomic stability. Mol Cancer Res...

Satellite data transferring subsystem based on system 'Materik'

International Nuclear Information System (INIS)

Belogub, V.P.; Kal'schikov, I.B.; Kirillov, Yu.K.; Kulikov, V.N.; Shumov, A.N.

1998-01-01

One of the most important indicators of successful function of the International Monitoring System is existence of highly reliable communication channels providing transfer data from observation points in a real time scales. Up to present, the most communication channels were provided with existing VF-channels (Voice Frequency) that are relatively low-speedy in transfer process (4.8-9.6 kbit/sec.). In addition, reliability of the channels is insufficient because of many retransmission points. In connection with it, the special control service of MD RF decided to improve the information transfer system (ITS) installed between the observation point and National Data Center (Dubna-city). The improvement of the ITS comprises replacement of wire lines of VF-channels with satellite ones within the framework of the computer-aided satellite communication system (CASCS) M aterik . Besides it was considered to be expedient that the satellite system of data transfer from NPP to the Crisis Center of 'ROSENERGOATOM' Concern would be combined with CASCS M aterik , using the facilities of the Central Earth Station of Satellite Communication (CESSC) in Dubna. Such approach to the creation of Satellite communication has advantages in solution of radiation safety and global monitoring issues

Satellites of radio AGN in SDSS: Insights into agn triggering and feedback

Energy Technology Data Exchange (ETDEWEB)

Pace, Cameron; Salim, Samir, E-mail: cjpace@indiana.edu, E-mail: salims@indiana.edu [Indiana University, Department of Astronomy, Swain Hall West 319, Bloomington, IN 47405-7105 (United States)

2014-04-10

We study the effects of radio jets on galaxies in their vicinity (satellites) and the role of satellites in triggering radio-loud active galactic nuclei (AGNs). The study compares the aggregate properties of satellites of a sample of 7220 radio AGNs at z < 0.3 (identified by Best and Heckman from the SDSS and NVSS+FIRST surveys) to the satellites of a control sample of radio-quiet galaxies, which are matched in redshift, color, luminosity, and axis ratio, as well as by environment type: field galaxies, cluster members, and brightest cluster galaxies (BCGs). Remarkably, we find that radio AGNs exhibit on average a 50% excess (17σ significance) in the number of satellites within 100 kpc even though the cluster membership was controlled (e.g., radio BCGs have more satellites than radio-quiet BCGs, etc.). Satellite excess is not confirmed for high-excitation sources, which are only 2% of radio AGN. Extra satellites may be responsible for raising the probability for hot gas AGN accretion via tidal effects or may otherwise enhance the intensity or duration of the radio-emitting phase. Furthermore, we find that the incidence of radio AGNs among potential hosts (massive ellipticals) is similar for field galaxies and for non-BCG cluster members, suggesting that AGN fueling depends primarily on conditions in the host halo rather than the parent, cluster halo. Regarding feedback, we find that radio AGNs, either high or low excitation, have no detectable effect on star formation in their satellites, as neither induced star formation nor star formation quenching is present in more than ∼1% of radio AGN.

Satellites of radio AGN in SDSS: Insights into agn triggering and feedback

International Nuclear Information System (INIS)

Pace, Cameron; Salim, Samir

2014-01-01

We study the effects of radio jets on galaxies in their vicinity (satellites) and the role of satellites in triggering radio-loud active galactic nuclei (AGNs). The study compares the aggregate properties of satellites of a sample of 7220 radio AGNs at z < 0.3 (identified by Best and Heckman from the SDSS and NVSS+FIRST surveys) to the satellites of a control sample of radio-quiet galaxies, which are matched in redshift, color, luminosity, and axis ratio, as well as by environment type: field galaxies, cluster members, and brightest cluster galaxies (BCGs). Remarkably, we find that radio AGNs exhibit on average a 50% excess (17σ significance) in the number of satellites within 100 kpc even though the cluster membership was controlled (e.g., radio BCGs have more satellites than radio-quiet BCGs, etc.). Satellite excess is not confirmed for high-excitation sources, which are only 2% of radio AGN. Extra satellites may be responsible for raising the probability for hot gas AGN accretion via tidal effects or may otherwise enhance the intensity or duration of the radio-emitting phase. Furthermore, we find that the incidence of radio AGNs among potential hosts (massive ellipticals) is similar for field galaxies and for non-BCG cluster members, suggesting that AGN fueling depends primarily on conditions in the host halo rather than the parent, cluster halo. Regarding feedback, we find that radio AGNs, either high or low excitation, have no detectable effect on star formation in their satellites, as neither induced star formation nor star formation quenching is present in more than ∼1% of radio AGN.

History of Satellite TV Broadcasting and Satellite Broadcasting Market in Turkey

Directory of Open Access Journals (Sweden)

Mihalis KUYUCU

2015-09-01

Full Text Available The present study analyses the satellite broadcasting that is the first important development that emerged as a result of digitalization in communication technologies and its reflections in Turkey. As the first milestone in the globalization of television broadcasting, satellite broadcasting provided substantial contribution towards the development of the media. Satellite bro adcasting both increased the broadcasting quality and geographical coverage of the television media. A conceptual study was carried out in the first part of the study in connection with the history of satellite broadcasting in Turkey and across the world. In the research part of the study, an analysis was performed on 160 television channels that broadcast in Turkey via Turksat Satellite. Economic structure of the television channels broadcasting in Turkey via satellite was studied and an analysis was perfo rmed on the operational structure of the channels. As a result of the study, it was emphasized that the television channels broadcasting via satellite platform also use other platforms for the purpose of spreading their broadcasts and television channel ow ners make investments in different branches of the media, too. Capital owners invest in different business areas other than the media although television channels broadcasting via Turksat mostly focus on thematic broadcasting and make effort to generate ec onomic income from advertisements. Delays are encountered in the course of the convergence between the new media and television channels that broadcast only from the satellite platform and such television channels experience more economic problems than the other channels. New media and many TV broadcasting platforms emerged as a result of the developments in the communication technologies. In television broadcasting, satellite platform is not an effective platform on its own. Channels make effort to reach t o more people by using other platforms in addition to

Conceptual design of a synchronous Mars telecommunications satellite

Science.gov (United States)

Badi, Deborah M.; Farmer, Jeffrey T.; Garn, Paul A.; Martin, Gary L.

1989-01-01

Future missions to Mars will require a communications system to link activities on the Martian surface with each other and with mission controllers on Earth. A conceptual design is presented for an aerosynchronous communications satellite to provide these links. The satellite provides the capability for voice, data/command, and video transmissions. The mission scenario assumed for the design is described, and a description of a single aerosynchronous satellite is explained. A viable spacecraft design is then presented. Communication band selection and channel allocation are discussed. The communications system conceptual design is presented along with the trades used in sizing each of the required antennas. Also, the analyses used to develop the supporting subsystem designs are described as is the communications impact on each subsystem design.

Mobile satellite service communications tests using a NASA satellite

Science.gov (United States)

Chambers, Katherine H.; Koschmeder, Louis A.; Hollansworth, James E.; ONeill, Jack; Jones, Robert E.; Gibbons, Richard C.

1995-01-01

Emerging applications of commercial mobile satellite communications include satellite delivery of compact disc (CD) quality radio to car drivers who can select their favorite programming as they drive any distance; transmission of current air traffic data to aircraft; and handheld communication of data and images from any remote corner of the world. Experiments with the enabling technologies and tests and demonstrations of these concepts are being conducted before the first satellite is launched by utilizing an existing NASA spacecraft.

Satellite Geomagnetism

DEFF Research Database (Denmark)

Olsen, Nils; Stolle, Claudia

2012-01-01

Observations of Earth’s magnetic field from space began more than 50 years ago. A continuous monitoring of the field using low Earth orbit (LEO) satellites, however, started only in 1999, and three satellites have taken highprecision measurements of the geomagnetic field during the past decade....... The unprecedented time-space coverage of their data opened revolutionary new possibilities for monitoring, understanding, and exploring Earth’s magnetic field. In the near future, the three-satellite constellation Swarm will ensure continuity of such measurement and provide enhanced possibilities to improve our...... ability to characterize and understand the many sources that contribute to Earth’s magnetic field. In this review, we summarize investigations of Earth’s interior and environment that have been possible through the analysis of high-precision magnetic field observations taken by LEO satellites....

Satellite Antenna Pointing Procedure Driven by the Ground Service Quality

Science.gov (United States)

Yasui, Yoshitsugu

A satellite antenna alignment technique is proposed to ensure terrestrial service quality for users. The antenna bore sight orientation is calculated directly from measured data acquired from general ground receivers, which intercept the communication radio waves from any position on the earth's surface. The method coordinates the satellite pointing parameters with signal strength at the receivers while considering location-specific geographical and antenna radiation characteristics and control accuracy. The theoretical development and its validity are examined in the course of equation derivation. Actual measured data of an existing satellite at the maneuver was applied to the method, and the capability was demonstrated and verified. With the wide diversity of satellite usage, such as for mobile communications, temporary network deployment or post-launch positioning accommodations, the proposed method provides a direct evaluation of satellite communication performance at the service level, in conjunction with using high frequency spot beam antennas, which are highly susceptible to pointing gain. This can facilitate swift and flexible satellite service planning and deployment for operators.

The Proba Satellite Star Tracker Performance

DEFF Research Database (Denmark)

Jørgensen, John Leif; Denver, Troelz; Betto, Maurizio

2005-01-01

ESA's PROBA satellite features a high degree of autonomy, both technologically and scientifically. It is build around a powerful command, data and AOCS controller and with its less than 100 kg it is a true microsatellite. The scientific mission of PROBA includes a scanning telescope, which calls ...

Handbook of satellite applications

CERN Document Server

Madry, Scott; Camacho-Lara, Sergio

2017-01-01

The first edition of this ground breaking reference work was the most comprehensive reference source available about the key aspects of the satellite applications field. This updated second edition covers the technology, the markets, applications and regulations related to satellite telecommunications, broadcasting and networking—including civilian and military systems; precise satellite navigation and timing networks (i.e. GPS and others); remote sensing and meteorological satellite systems. Created under the auspices of the International Space University based in France, this brand new edition is now expanded to cover new innovative small satellite constellations, new commercial launching systems, innovation in military application satellites and their acquisition, updated appendices, a useful glossary and more.

Earth Observing System/Meteorological Satellite (EOS/METSAT). Advanced Microwave Sounding Unit-A (AMSU-A) Contamination Control Plan

Science.gov (United States)

Fay, M.

1998-01-01

This Contamination Control Plan is submitted in response the Contract Document requirements List (CDRL) 007 under contract NAS5-32314 for the Earth Observing System (EOS) Advanced Microwave Sounding Unit A (AMSU-A). In response to the CDRL instructions, this document defines the level of cleanliness and methods/procedures to be followed to achieve adequate cleanliness/contamination control, and defines the required approach to maintain cleanliness/contamination control through shipping, observatory integration, test, and flight. This plan is also applicable to the Meteorological Satellite (METSAT) except where requirements are identified as EOS-specific. This plan is based on two key factors: a. The EOS/METSAT AMSU-A Instruments are not highly contamination sensitive. b. Potential contamination of other EOS Instruments is a key concern as addressed in Section 9/0 of the Performance Assurance Requirements for EOS/METSAT Integrated Programs AMSU-A Instrument (MR) (NASA Specification S-480-79).

Trends in communications satellites

CERN Document Server

Curtin, Denis J

1979-01-01

Trends in Communications Satellites offers a comprehensive look at trends and advances in satellite communications, including experimental ones such as NASA satellites and those jointly developed by France and Germany. The economic aspects of communications satellites are also examined. This book consists of 16 chapters and begins with a discussion on the fundamentals of electrical communications and their application to space communications, including spacecraft, earth stations, and orbit and wavelength utilization. The next section demonstrates how successful commercial satellite communicati

A Novel Wide-Area Backup Protection Based on Fault Component Current Distribution and Improved Evidence Theory

Directory of Open Access Journals (Sweden)

Zhe Zhang

2014-01-01

Full Text Available In order to solve the problems of the existing wide-area backup protection (WABP algorithms, the paper proposes a novel WABP algorithm based on the distribution characteristics of fault component current and improved Dempster/Shafer (D-S evidence theory. When a fault occurs, slave substations transmit to master station the amplitudes of fault component currents of transmission lines which are the closest to fault element. Then master substation identifies suspicious faulty lines according to the distribution characteristics of fault component current. After that, the master substation will identify the actual faulty line with improved D-S evidence theory based on the action states of traditional protections and direction components of these suspicious faulty lines. The simulation examples based on IEEE 10-generator-39-bus system show that the proposed WABP algorithm has an excellent performance. The algorithm has low requirement of sampling synchronization, small wide-area communication flow, and high fault tolerance.

A Novel Wide-Area Backup Protection Based on Fault Component Current Distribution and Improved Evidence Theory

Science.gov (United States)

Zhang, Zhe; Kong, Xiangping; Yin, Xianggen; Yang, Zengli; Wang, Lijun

2014-01-01

In order to solve the problems of the existing wide-area backup protection (WABP) algorithms, the paper proposes a novel WABP algorithm based on the distribution characteristics of fault component current and improved Dempster/Shafer (D-S) evidence theory. When a fault occurs, slave substations transmit to master station the amplitudes of fault component currents of transmission lines which are the closest to fault element. Then master substation identifies suspicious faulty lines according to the distribution characteristics of fault component current. After that, the master substation will identify the actual faulty line with improved D-S evidence theory based on the action states of traditional protections and direction components of these suspicious faulty lines. The simulation examples based on IEEE 10-generator-39-bus system show that the proposed WABP algorithm has an excellent performance. The algorithm has low requirement of sampling synchronization, small wide-area communication flow, and high fault tolerance. PMID:25050399

Ballistic Aspects of Feasibility for Prospective Satellite Navigation Technologies

Directory of Open Access Journals (Sweden)

L. N. Lysenko

2015-01-01

Full Text Available When modeling the operating processes of ballistics and navigation support it is expedient to make decomposition of the general problem of coordinate-time and navigation support into the typical options of its engineering implementation.As the satellite navigation technologies the paper considers inter-satellite measurement and autonomous navigation mode of differential correction. It also assesses the possibility of their application to improve the accuracy of navigation determinations.Technologies using inter-satellite measurement tools such as GLONASS / GPS equipment, equipment of inter-satellite radio link, astro-optical space based devices are an independent class of navigation technologies.However, each of these options has both advantages and disadvantages that affect the eva luation of the appropriateness and feasibility of their use.The paper separately considers the problem of increasing survivability of space systems and conservation of ground control complex due to introduction of requirements to ensure the independent functioning of spacecraft and application of technologies of ballistics and navigation support, supposing to involve minimum means of automated ground control complex for these purposes.Currently, there is a completely developed theory of autonomous navigation based on astronomical positional gauges, which are used as onboard optical sensors of orientation and stabilization systems.To date, the differential navigation mode is, virtually, the only approach that can allow the olution of tasks in terms of increased accuracy, but with some restrictions.The implementation of differential mode of treatment is carried out through the creation of differential subsystems of the satellite navigation systems. These subsystems are usually divided into wide-range, regional and local ones.Analysis of ballistic aspects to implement discussed navigation technologies allowed us to identify constraints for improving accuracy to define

Theory of satellite geodesy applications of satellites to geodesy

CERN Document Server

Kaula, William M

2000-01-01

The main purpose of this classic text is to demonstrate how Newtonian gravitational theory and Euclidean geometry can be used and developed in the earth's environment. The second is to collect and explain some of the mathematical techniques developed for measuring the earth by satellite.Book chapters include discussions of the earth's gravitational field, with special emphasis on spherical harmonies and the potential of the ellipsoid; matrices and orbital geometry; elliptic motion, linear perturbations, resonance, and other aspects of satellite orbit dynamics; the geometry of satellite obser

Satellite formation flying relative dynamics, formation design, fuel optimal maneuvers and formation maintenance

CERN Document Server

Wang, Danwei; Poh, Eng Kee

2017-01-01

This book systematically describes the concepts and principles for multi-satellite relative motion, passive and near passive formation designs, trajectory planning and control for fuel optimal formation maneuvers, and formation flying maintenance control design. As such, it provides a sound foundation for researchers and engineers in this field to develop further theories and pursue their implementations. Though satellite formation flying is widely considered to be a major advance in space technology, there are few systematic treatments of the topic in the literature. Addressing that gap, the book offers a valuable resource for academics, researchers, postgraduate students and practitioners in the field of satellite science and engineering.

Drying of Rhinacanthus nasutus (Linn. Kurz. using a solar dryer incorporated with a backup thermal energy storage from wood combustion

Directory of Open Access Journals (Sweden)

Perapong Tekasakul

2006-05-01

Full Text Available An indirect, natural convection, solar cabinet dryer incorporated with a backup thermal energy storage from wood combustion was designed and tested with the Thai herb, Rhinacanthus nasutus (Linn. Kurz. Most of Thai herbs are widely used as traditional medicine and drying is an initial step in the production process. Solar dryer with a biomass backup heating system is the most feasible solution to drying in Thailand. In this work, a 4 m x 5 m solar collector was used to absorb solar radiation for heating the incoming air during the daytime, while a biomass burner was used to supply heat when solar energy was not possible. Heat from fuelwood combustion was accumulated in the thermal storage system made of bricks, and was used to heat up the incoming air. Results showed that the herb was dried uniformly and the temperature inside the drying cabinet could be maintained above 50ºC for more than 10 hours. Thermal efficiency when using solar energy was 10.5%, but the value was less than 1% when using the heat from biomass burning. This resulted from the low moisture content of the products after being dried by the solar energy. The dryer is beneficial to the operators, particularly in southern Thailand, where continuous drying is required. This dryer is by no means limited to drying of the herb. Currently, four dryers of the same model have been used by farmer groups in southern Thailand for drying bananas, several types of herbs, fish, and other products. In economic consideration, its payback period is 5.5 years when compared with the LPG-equipped dryer. When the total cost and production capacity are considered, its payback period is about 6 years.

Rayleigh Instability-Assisted Satellite Droplets Elimination in Inkjet Printing.

Science.gov (United States)

Yang, Qiang; Li, Huizeng; Li, Mingzhu; Li, Yanan; Chen, Shuoran; Bao, Bin; Song, Yanlin

2017-11-29

Elimination of satellite droplets in inkjet printing has long been desired for high-resolution and precision printing of functional materials and tissues. Generally, the strategy to suppress satellite droplets is to control ink properties, such as viscosity or surface tension, to assist ink filaments in retracting into one drop. However, this strategy brings new restrictions to the ink, such as ink viscosity, surface tension, and concentration. Here, we report an alternative strategy that the satellite droplets are eliminated by enhancing Rayleigh instability of filament at the break point to accelerate pinch-off of the droplet from the nozzle. A superhydrophobic and ultralow adhesive nozzle with cone morphology exhibits the capability to eliminate satellite droplets by cutting the ink filament at breakup point effectively. As a result, the nozzles with different sizes (10-80 μm) are able to print more inks (1 printing electronics and biotechnologies.

GLONASS satellite monitoring of nuclear transports

International Nuclear Information System (INIS)

Davydov, Yu.L.

2012-01-01

In 2011 Rosatom has made the decision to create the industry-wide automated system for monitoring of transports of radioactive substances (RS) and wastes (RAW), as well as hazardous loads by rail and automobile, based upon the same hardware as used by the GLONASS satellite navigation system - the so-called ASBT-GLONASS system. The new system will use the same technical infrastructure as the existing operational Automated System for Safe Transport of Nuclear Materials of Categories I and II (ASBT). The ASBT structure includes a network of control centres fitted with automation and communication hardware. In addition, ASBT includes technical complexes installed upon transport vehicles intended for nuclear material transport. In order to identify transport vehicle location, the GLONASS/GPS (GALS-P-ASBT) satellite navigational receiver device is used, it is developed especially for ASBT systems taking in account information security requirements. By now the basic software and hardware complex ASBT-GLONASS has been created (equipment to be carried on-board the transport vehicle loaded with RS and RAW, as well as the transport control stations) that supports transport monitoring and transmission of an emergency signal to control stations of companies which deal with RS and RAW transportation [ru

Software Design of Mobile Antenna for Auto Satellite Tracking Using Modem Correction and Elevation Azimuth Method

Directory of Open Access Journals (Sweden)

Djamhari Sirat

2010-10-01

Full Text Available Pointing accuracy is an important thing in satellite communication. Because the satellite’s distance to the surface of the earth's satellite is so huge, thus 1 degree of pointing error will make the antenna can not send data to satellites. To overcome this, the auto-tracking satellite controller is made. This system uses a microcontroller as the controller, with the GPS as the indicator location of the antenna, digital compass as the beginning of antenna pointing direction, rotary encoder as sensor azimuth and elevation, and modem to see Eb/No signal. The microcontroller use serial communication to read the input. Thus the programming should be focused on in the UART and serial communication software UART. This controller use 2 phase in the process of tracking satellites. Early stages is the method Elevation-Azimuth, where at this stage with input from GPS, Digital Compass, and the position of satellites (both coordinates, and height that are stored in microcontroller. Controller will calculate the elevation and azimuth angle, then move the antenna according to the antenna azimuth and elevation angle. Next stages is correction modem, where in this stage controller only use modem as the input, and antenna movement is set up to obtain the largest value of Eb/No signal. From the results of the controller operation, there is a change in the value of the original input level from -81.7 dB to -30.2 dB with end of Eb/No value, reaching 5.7 dB.

A high-speed, multi-input serial-interfacing system for a computer with simultaneous back-up recording on magnetic tape

International Nuclear Information System (INIS)

Andeweg, A.H.

1983-01-01

A system has been developed that interfaces nuclear-instrument data modules and a multichannel analyser into a computer. The interface converts 4-bit binary-coded decimal (BCD) data into 8-bit packed BCD data, and converts the parallel data into serial data. The data are transmitted up to a distance of 500m at a transfer rate of 153,6kbaud via an RS422 transmission link to a central computer system. One or more multichannel analyser systems can be connected to the system via a routine device. The routing device serves these analysers on a first-come-first-served mode. The data transmitted to the computer system are recorded simultaneously on a digital magnetic-tape drive to provide a back-up facility

Implementation and Test of the Automatic Flight Dynamics Operations for Geostationary Satellite Mission

Directory of Open Access Journals (Sweden)

Sangwook Park

2009-12-01

Full Text Available This paper describes the Flight Dynamics Automation (FDA system for COMS Flight Dynamics System (FDS and its test result in terms of the performance of the automation jobs. FDA controls the flight dynamics functions such as orbit determination, orbit prediction, event prediction, and fuel accounting. The designed FDA is independent from the specific characteristics which are defined by spacecraft manufacturer or specific satellite missions. Therefore, FDA could easily links its autonomous job control functions to any satellite mission control system with some interface modification. By adding autonomous system along with flight dynamics system, it decreases the operator’s tedious and repeated jobs but increase the usability and reliability of the system. Therefore, FDA is used to improve the completeness of whole mission control system’s quality. The FDA is applied to the real flight dynamics system of a geostationary satellite, COMS and the experimental test is performed. The experimental result shows the stability and reliability of the mission control operations through the automatic job control.

Performance experiments with alternative advanced teleoperator control modes for a simulated solar maximum satellite repair

Science.gov (United States)

Das, H.; Zak, H.; Kim, W. S.; Bejczy, A. K.; Schenker, P. S.

1992-01-01

Experiments are described which were conducted at the JPL Advanced Teleoperator Lab to demonstrate and evaluate the effectiveness of various teleoperator control modes in the performance of a simulated Solar Max Satellite Repair (SMSR) task. THe SMSR was selected as a test because it is very rich in performance capability requirements and it actually has been performed by two EVA astronauts in the Space Shuttle Bay in 1984. The main subtasks are: thermal blanket removal; installation of a hinge attachment for electrical panel opening; opening of electrical panel; removal of electrical connectors; relining of cable bundles; replacement of electrical panel; securing parts and cables; re-mate electrical connectors; closing of electrical panel; and reinstating thermal blanket. The current performance experiments are limited to thermal blanket cutting, electrical panel unbolting and handling electrical bundles and connectors. In one formal experiment even different control modes were applied to the unbolting and reinsertion of electrical panel screws subtasks. The seven control modes are alternative combinations of manual position and rate control with force feedback and remote compliance referenced to force-torque sensor information. Force-torque sensor and end effector position data and task completion times were recorded for analysis and quantification of operator performance.

Satellite Communications

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Satellite Communications. Arthur C Clarke wrote a seminal paper in 1945 in wireless world. Use three satellites in geo-synchronous orbit to enable intercontinental communications. System could be realised in '50 to 100 years'

Effects of voluntary wheel running on satellite cells in the rat plantaris muscle.

Science.gov (United States)

Kurosaka, Mitsutoshi; Naito, Hisashi; Ogura, Yuji; Kojima, Atsushi; Goto, Katsumasa; Katamoto, Shizuo

2009-01-01

This study investigated the effects of voluntary wheel running on satellite cells in the rat plantaris muscle. Seventeen 5-week-old male Wistar rats were assigned to a control (n = 5) or training (n = 12) group. Each rat in the training group ran voluntarily in a running-wheel cage for 8 weeks. After the training period, the animals were anesthetized, and the plantaris muscles were removed, weighed, and analyzed immunohistochemically and biochemically. Although there were no significant differences in muscle weight or fiber area between the groups, the numbers of satellite cells and myonuclei per muscle fiber, percentage of satellite cells, and citrate synthase activity were significantly higher in the training group compared with the control group (p run in the training group (r = 0.61, p running can induce an increase in the number of satellite cells without changing the mean fiber area in the rat plantaris muscle; this increase in satellite cell content is a function of distance run. Key pointsThere is no study about the effect of voluntary running on satellite cells in the rat plantaris muscle.Voluntary running training causes an increase of citrate synthase activity in the rat plantaris muscle but does not affect muscle weight and mean fiber area in the rat plantaris muscle.Voluntary running can induce an increase in the number of satellite cells without hypertrophy of the rat plantaris muscle.

Control and Protection Cooperation Strategy for Voltage Instability

DEFF Research Database (Denmark)

Liu, Zhou; Chen, Zhe; Sun, Haishun

2012-01-01

Most cascaded blackouts are caused by unexpected backup relay operations due to low voltage or overload state caused by post fault load restoration dynamics. If such state can be sensed and adjusted appropriately prior to those relay actions, system stability might be sustained. This paper proposed...... a control and protection cooperation strategy to prevent post fault voltage instability. The multi-agent technology is applied for the strategy implementation; the criteria based on wide area measured apparent impedances are defined to choose the control strategy, such as tap changer adjusting or load...

The Potential Uses of Commercial Satellite Imagery in the Middle East

Energy Technology Data Exchange (ETDEWEB)

Vannoni, M.G.

1999-06-08

It became clear during the workshop that the applicability of commercial satellite imagery to the verification of future regional arms control agreements is limited at this time. Non-traditional security topics such as environmental protection, natural resource management, and the development of infrastructure offer the more promising applications for commercial satellite imagery in the short-term. Many problems and opportunities in these topics are regional, or at least multilateral, in nature. A further advantage is that, unlike arms control and nonproliferation applications, cooperative use of imagery in these topics can be done independently of the formal Middle East Peace Process. The value of commercial satellite imagery to regional arms control and nonproliferation, however, will increase during the next three years as new, more capable satellite systems are launched. Aerial imagery, such as that used in the Open Skies Treaty, can also make significant contributions to both traditional and non-traditional security applications but has the disadvantage of requiring access to national airspace and potentially higher cost. There was general consensus that commercial satellite imagery is under-utilized in the Middle East and resources for remote sensing, both human and institutional, are limited. This relative scarcity, however, provides a natural motivation for collaboration in non-traditional security topics. Collaborations between scientists, businesses, universities, and non-governmental organizations can work at the grass-roots level and yield contributions to confidence building as well as scientific and economic results. Joint analysis projects would benefit the region as well as establish precedents for cooperation.

Key issues of multiple access technique for LEO satellite communication systems

Institute of Scientific and Technical Information of China (English)

温萍萍; 顾学迈

2004-01-01

The large carrier frequency shift caused by the high-speed movement of satellite (Doppler effects) and the propagation delay on the up-down link are very critical issues in an LEO satellite communication system, which affects both the selection and the implementation of a suitable access method. A Doppler based multiple access technique is used here to control the flow and an MPRMA-HS protocol is proposed for the application in LEO satellite communication systems. The extended simulation trials prove that the proposed scheme seems to be a very promising access method.

Satellite Dynamics and Control in a Quaternion Formulation (2nd edition)

DEFF Research Database (Denmark)

Blanke, Mogens; Larsen, Martin Birkelund

to represent rotation. A general linearised model is derived such that the user can specify an arbitrary point of operation in angular velocity and wheel angular momentum, specifying the a inertia matrix for a rigid satellite. A set of Simulink® models that simulate the satellite’s nonlinear behaviour...

Geostationary Satellite (GOES) Images

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from radiometer instruments on SMS (ATS) and GOES satellites in geostationary orbit. These satellites produced...

Phase Change Material for Temperature Control of Imager or Sounder on GOES Type Satellites in GEO

Science.gov (United States)

Choi, Michael K.

2014-01-01

This paper uses phase change material (PCM) in the scan cavity of an imager or sounder on satellites in geostationary orbit (GEO) to maintain the telescope temperature stable. When sunlight enters the scan aperture, solar heating causes the PCM to melt. When sunlight stops entering the scan aperture, the PCM releases the thermal energy stored to keep the components in the telescope warm. It has no moving parts or bimetallic springs. It reduces heater power required to make up the heat lost by radiation to space through the aperture. It is an attractive thermal control option to a radiator with a louver and a sunshade.

Theory of geostationary satellites

CERN Document Server

Zee, Chong-Hung

1989-01-01

Geostationary or equatorial synchronous satellites are a daily reminder of our space efforts during the past two decades. The nightly television satellite weather picture, the intercontinental telecommunications of television transmissions and telephone conversations, and the establishrnent of educational programs in remote regions on Earth are constant reminders of the presence of these satellites. As used here, the term 'geo­ stationary' must be taken loosely because, in the long run, the satellites will not remain 'stationary' with respect to an Earth-fixed reference frame. This results from the fact that these satellites, as is true for all satellites, are incessantly subject to perturbations other than the central-body attraction of the Earth. Among the more predominant pertur­ bations are: the ellipticity of the Earth's equator, the Sun and Moon, and solar radiation pressure. Higher harmonics of the Earth's potential and tidal effects also influence satellite motion, but they are of second­ order whe...

Space Solar Power Satellite Systems, Modern Small Satellites, and Space Rectenna

Science.gov (United States)

Bergsrud, Corey Alexis Marvin

Space solar power satellite (SSPS) systems is the concept of placing large satellite into geostationary Earth orbit (GEO) to harvest and convert massive amounts of solar energy into microwave energy, and to transmit the microwaves to a rectifying antenna (rectenna) array on Earth. The rectenna array captures and converts the microwave power into usable power that is injected into the terrestrial electric grid for use. This work approached the microwave power beam as an additional source of power (with solar) for lower orbiting satellites. Assuming the concept of retrodirectivity, a GEO-SSPS antenna array system tracks and delivers microwave power to lower orbiting satellites. The lower orbiting satellites are equipped with a stacked photovoltaic (PV)/rectenna array hybrid power generation unit (HPGU) in order to harvest solar and/or microwave energy for on-board use during orbit. The area, and mass of the PV array part of the HPGU was reduced at about 32% beginning-of-life power in order to achieve the spacecraft power requirements. The HPGU proved to offer a mass decrease in the PGU, and an increase in mission life due to longer living component life of the rectenna array. Moreover, greater mission flexibility is achieved through a track and power delivery concept. To validate the potential advantages offered by a HPGU, a mission concept was presented that utilizes modern small satellites as technology demonstrators. During launch, a smaller power receiving "daughter" satellite sits inside a larger power transmitting "mother" satellite. Once separated from the launch vehicle the daughter satellite is ejected away from the mother satellite, and each satellite deploys its respective power transmitting or power receiving hardware's for experimentation. The concept of close proximity mission operations between the satellites is considered. To validate the technology of the space rectenna array part of the HPGU, six milestones were completed in the design. The first

HDAC4 regulates satellite cell proliferation and differentiation by targeting P21 and Sharp1 genes.

Science.gov (United States)

Marroncelli, Nicoletta; Bianchi, Marzia; Bertin, Marco; Consalvi, Silvia; Saccone, Valentina; De Bardi, Marco; Puri, Pier Lorenzo; Palacios, Daniela; Adamo, Sergio; Moresi, Viviana

2018-02-22

Skeletal muscle exhibits a high regenerative capacity, mainly due to the ability of satellite cells to replicate and differentiate in response to appropriate stimuli. Epigenetic control is effective at different stages of this process. It has been shown that the chromatin-remodeling factor HDAC4 is able to regulate satellite cell proliferation and commitment. However, its molecular targets are still uncovered. To explain the signaling pathways regulated by HDAC4 in satellite cells, we generated tamoxifen-inducible mice with conditional inactivation of HDAC4 in Pax7 + cells (HDAC4 KO mice). We found that the proliferation and differentiation of HDAC4 KO satellite cells were compromised, although similar amounts of satellite cells were found in mice. Moreover, we found that the inhibition of HDAC4 in satellite cells was sufficient to block the differentiation process. By RNA-sequencing analysis we identified P21 and Sharp1 as HDAC4 target genes. Reducing the expression of these target genes in HDAC4 KO satellite cells, we also defined the molecular pathways regulated by HDAC4 in the epigenetic control of satellite cell expansion and fusion.

SatelliteDL: a Toolkit for Analysis of Heterogeneous Satellite Datasets

Science.gov (United States)

Galloy, M. D.; Fillmore, D.

2014-12-01

SatelliteDL is an IDL toolkit for the analysis of satellite Earth observations from a diverse set of platforms and sensors. The core function of the toolkit is the spatial and temporal alignment of satellite swath and geostationary data. The design features an abstraction layer that allows for easy inclusion of new datasets in a modular way. Our overarching objective is to create utilities that automate the mundane aspects of satellite data analysis, are extensible and maintainable, and do not place limitations on the analysis itself. IDL has a powerful suite of statistical and visualization tools that can be used in conjunction with SatelliteDL. Toward this end we have constructed SatelliteDL to include (1) HTML and LaTeX API document generation,(2) a unit test framework,(3) automatic message and error logs,(4) HTML and LaTeX plot and table generation, and(5) several real world examples with bundled datasets available for download. For ease of use, datasets, variables and optional workflows may be specified in a flexible format configuration file. Configuration statements may specify, for example, a region and date range, and the creation of images, plots and statistical summary tables for a long list of variables. SatelliteDL enforces data provenance; all data should be traceable and reproducible. The output NetCDF file metadata holds a complete history of the original datasets and their transformations, and a method exists to reconstruct a configuration file from this information. Release 0.1.0 distributes with ingest methods for GOES, MODIS, VIIRS and CERES radiance data (L1) as well as select 2D atmosphere products (L2) such as aerosol and cloud (MODIS and VIIRS) and radiant flux (CERES). Future releases will provide ingest methods for ocean and land surface products, gridded and time averaged datasets (L3 Daily, Monthly and Yearly), and support for 3D products such as temperature and water vapor profiles. Emphasis will be on NPP Sensor, Environmental and

Interim Service ISDN Satellite (ISIS) network model for advanced satellite designs and experiments

Science.gov (United States)

Pepin, Gerard R.; Hager, E. Paul

1991-01-01

The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Network Model for Advanced Satellite Designs and Experiments describes a model suitable for discrete event simulations. A top-down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ISDN modeling abstractions are added to permit the determination and performance for the NASA Satellite Communications Research (SCAR) Program.

Development of a PC-based ground support system for a small satellite instrument

Science.gov (United States)

Deschambault, Robert L.; Gregory, Philip R.; Spenler, Stephen; Whalen, Brian A.

1993-11-01

The importance of effective ground support for the remote control and data retrieval of a satellite instrument cannot be understated. Problems with ground support may include the need to base personnel at a ground tracking station for extended periods, and the delay between the instrument observation and the processing of the data by the science team. Flexible solutions to such problems in the case of small satellite systems are provided by using low-cost, powerful personal computers and off-the-shelf software for data acquisition and processing, and by using Internet as a communication pathway to enable scientists to view and manipulate satellite data in real time at any ground location. The personal computer based ground support system is illustrated for the case of the cold plasma analyzer flown on the Freja satellite. Commercial software was used as building blocks for writing the ground support equipment software. Several levels of hardware support, including unit tests and development, functional tests, and integration were provided by portable and desktop personal computers. Satellite stations in Saskatchewan and Sweden were linked to the science team via phone lines and Internet, which provided remote control through a central point. These successful strategies will be used on future small satellite space programs.

An Autonomous Satellite Time Synchronization System Using Remotely Disciplined VC-OCXOs

Directory of Open Access Journals (Sweden)

Xiaobo Gu

2015-07-01

Full Text Available An autonomous remote clock control system is proposed to provide time synchronization and frequency syntonization for satellite to satellite or ground to satellite time transfer, with the system comprising on-board voltage controlled oven controlled crystal oscillators (VC-OCXOs that are disciplined to a remote master atomic clock or oscillator. The synchronization loop aims to provide autonomous operation over extended periods, be widely applicable to a variety of scenarios and robust. A new architecture comprising the use of frequency division duplex (FDD, synchronous time division (STDD duplex and code division multiple access (CDMA with a centralized topology is employed. This new design utilizes dual one-way ranging methods to precisely measure the clock error, adopts least square (LS methods to predict the clock error and employs a third-order phase lock loop (PLL to generate the voltage control signal. A general functional model for this system is proposed and the error sources and delays that affect the time synchronization are discussed. Related algorithms for estimating and correcting these errors are also proposed. The performance of the proposed system is simulated and guidance for selecting the clock is provided.

Jovian magnetosphere-satellite interactions: aspects of energetic charged particle loss

International Nuclear Information System (INIS)

Thomsen, M.F.

1979-01-01

Observations of energetic charged particles obtained by Pioneers 10 and 11 near the orbits of the inner Jovian satellites are reviewed with particular emphasis on the implications of these observations with regard to possible models of the access of charged particles to the satellite surfaces. The observed effects on particle pitch angle distributions and the observed energy dependence of the intensity depletions seen at the satellite orbits are compared with predictions of satellite sweepup based on several different access models. The two major uncertainties which hamper the comparisons are those associated with the satellite conductivities and the ionospheric dynamo electric field power spectrum. The satellite conductivity is important because it governs the access of the particles to the satellite surface and therefore the lifetime tau: the dynamo power spectrum is important because it controls the magnitude and energy dependence of the radial diffusion coefficient. In spite of these uncertainties we can nevertheless make the following conclusions. The electron pitch angle distributions at Io's orbit are compatible with expectations based on sweeping. The energy dependences of the observed electron depletions at all three inner satellites (Amalthea, Io, and Europa) are incompatible with expectations based on a perfect conductor model of a satellite and its flux tube but are compatible with the energy dependence expected for perfectly insulating or partially conducting satellites However, the proton losses at Io are observed to be much stronger than the electron losses, in contradiction to expectations based on sweeping. The most attractive explanation for the proton-electron discrepancy at Io is that the large proton losses at Io's orbit are principally due to enhanced pitch angle scattering in the region of higher plasma density

A Fiducial Reference Stie for Satellite Altimetry in Crete, Greece

Science.gov (United States)

Mertikas, Stelios; Donlon, Craig; Mavrocordatos, Constantin; Bojkov, Bojan; Femenias, Pierre; Parrinello, Tommaso; Picot, Nicolas; Desjonqueres, Jean-Damien; Andersen, Ole Baltazar

2016-08-01

With the advent of diverse satellite altimeters and variant measuring techniques, it has become mature in the scientific community, that an absolute reference Cal/Val site is regularly maintained to define, monitor, control the responses of any altimetric system.This work sets the ground for the establishment of a Fiducial Reference Site for ESA satellite altimetry in Gavdos and West Crete, Greece. It will consistently and reliably determine (a) absolute altimeter biases and their drifts; (b) relative bias among diverse missions; but also (c) continuously and independently connect different missions, on a common and reliable reference and also to SI-traceable measurements. Results from this fiducial reference site will be based on historic Cal/Val site measurement records, and will be the yardstick for building up capacity for monitoring climate change. This will be achieved by defining and assessing any satellite altimeter measurements to known, controlled and absolute reference signals with different techniques, processes and instrumentation.

The investigation of tethered satellite system dynamics

Science.gov (United States)

Lorenzini, E. C.

1986-01-01

The analysis of the rotational dynamics of the satellite was focused on the rotational amplitude increase of the satellite, with respect to the tether, during retrieval. The dependence of the rotational amplitude upon the tether tension variation to the power 1/4 was thoroughly investigated. The damping of rotational oscillations achievable by reel control was also quantified while an alternative solution that makes use of a lever arm attached with a universal joint to the satellite was proposed. Comparison simulations between the Smithsonian Astrophysical Observatory and the Martin Marietta (MMA) computer code of reteival maneuvers were also carried out. The agreement between the two, completely independent, codes was extremely close, demonstrating the reliability of the models. The slack tether dynamics during reel jams was analytically investigated in order to identify the limits of applicability of the SLACK3 computer code to this particular case. Test runs with SLACK3 were also carried out.

Research on control function switch of nuclear power plant control room

International Nuclear Information System (INIS)

Mei Shibo; Mao Ting; Cheng Bo; Zhang Gang

2014-01-01

The nuclear power plant provides main control room (MCR) to the unit operators for the plant monitoring and control, and provides the remote shutdown station (RSS) as the back-up control room, which is used only when MCR is unavailable. The RSS could be used to monitor and control the plant, bring the plant into shutdown state and remove the residual heat. The command from MCR and RSS is blocked by each other and can not be executed at the same time. The operation mode switch function between MCR and RSS is carried out by MCR/RSS mode switches. The operation mode switch scheme of CPR1000, ERP and AP1000 were compared and researched, and some design bases for new nuclear power plant were submitted in this paper. These design bases could be referred during the design of control function switch for the new nuclear power plants, in order to put forward a more practical, simple, safe and convenient scheme. (authors)

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

Telemedicine in general neurology: use of audiovisual consultation for on call back-up service in an acute care hospital.

Science.gov (United States)

Janssen, Frank; Awadallah, Mohammed; Alhalabi, Awed; Körber, Barbara; Lang, Reinhard; Scibor, Mateusz; Handschu, René

2018-04-01

While telemedicine is in expanding use in acute stroke care, little is known about its use in general neurology, especially in acute care. We sought to investigate the feasibility and possible effects of a telemedicine device within the neurological back-up service of an acute care hospital. In a 450 bed academic teaching hospital an experienced neurologist (EN) is on call to support the junior doctor at the hospital. Support was possible whether by standard telephone advice (TA) or by audiovisual consultations (AVC). In AVC the expert used a mobile telemedicine device and so he could establish audiovisual contact from his home to the emergency room and examine newly admitted patients. Technical and patient details including timing and diagnosis were recorded. Video and audio quality as well as impact of AVC on diagnosis was rated by the EN. Out of about 1200 cases in off peak times, during the study period, 164 AVC including remote video examination were done (13.6%). Also 48 cases were documented by pure TA. Video quality was rated to a medium of 1.7, audio quality to 2.1. In 36 cases the audiovisual consultation was influenced by technical issues leading to cessation of AVC in 8 cases. Duration of teleconsultation was 17.3 min in AVC compared to 8.7 min for TA. The consultation diagnosis in AVC was confirmed in 74.4% of all cases compared to 57.7% in TA. AVC was rated as a valuable contribution to the diagnostic workup in 74.3% of all cases seen. In about 40% of all cases AVC was not possible due to technical or organizational reasons. Audiovisual consultation seems to be a feasible and useful support in routine neurology back-up service of an acute care hospital. Better mobility of devices and flexibility of service is needed to improve availability and quality of this valuable tool.

The American Satellite Company (ASC) satellite deployed from payload bay

Science.gov (United States)

1985-01-01

The American Satellite Company (ASC) communications satellite is deployed from the payload bay of the Shuttle Discovery. A portion of the cloudy surface of the earth can be seen to the left of the frame.

Load-Following Voltage Controller Design for a Static Space Nuclear Power System

International Nuclear Information System (INIS)

Parlos, Alexander G.; Onbasioglou, Fetiye O.; Metzger, John D.

2000-01-01

The reliability of static space nuclear power systems (SNPSs) could be improved through the use of backup devices in addition to shunt regulators, as currently proposed for load following. Shunt regulator failure leading to reactor shutdown is possible, as is the possible need to deliver somewhat higher power level to the load than originally expected. A backup system is proposed in SNPSs to eliminate the possibility of a single-point failure in the shunt regulators and to increase the overall system power delivery capability despite changing mission needs and component characteristics. The objective of this paper is to demonstrate the feasibility of such a backup device for voltage regulation in static SNPSs that is capable of overcoming system variations resulting from operation at different power levels. A dynamic compensator is designed using the Linear Quadratic Gaussian with Loop Transfer Recovery method. The resulting compensators are gain scheduled using the SNPS electric power as the scheduling variable, resulting in a nonlinear compensator. The performance of the gain-scheduled compensator is investigated extensively using an SNPS simulator. The simulations demonstrate the effects of the fuel temperature reactivity coefficient variations on the load-following capabilities of the SNPS. Robustness analysis results demonstrate that the proposed controller exhibits significant operational flexibility, and it can be considered for long-term space mission requiring significant levels of autonomy

Ground Simulation of an Autonomous Satellite Rendezvous and Tracking System Using Dual Robotic Systems

Science.gov (United States)

Trube, Matthew J.; Hyslop, Andrew M.; Carignan, Craig R.; Easley, Joseph W.

2012-01-01

A hardware-in-the-loop ground system was developed for simulating a robotic servicer spacecraft tracking a target satellite at short range. A relative navigation sensor package "Argon" is mounted on the end-effector of a Fanuc 430 manipulator, which functions as the base platform of the robotic spacecraft servicer. Machine vision algorithms estimate the pose of the target spacecraft, mounted on a Rotopod R-2000 platform, relay the solution to a simulation of the servicer spacecraft running in "Freespace", which performs guidance, navigation and control functions, integrates dynamics, and issues motion commands to a Fanuc platform controller so that it tracks the simulated servicer spacecraft. Results will be reviewed for several satellite motion scenarios at different ranges. Key words: robotics, satellite, servicing, guidance, navigation, tracking, control, docking.

Trends in mobile satellite communication

Science.gov (United States)

Johannsen, Klaus G.; Bowles, Mike W.; Milliken, Samuel; Cherrette, Alan R.; Busche, Gregory C.

1993-01-01

Ever since the U.S. Federal Communication Commission opened the discussion on spectrum usage for personal handheld communication, the community of satellite manufacturers has been searching for an economically viable and technically feasible satellite mobile communication system. Hughes Aircraft Company and others have joined in providing proposals for such systems, ranging from low to medium to geosynchronous orbits. These proposals make it clear that the trend in mobile satellite communication is toward more sophisticated satellites with a large number of spot beams and onboard processing, providing worldwide interconnectivity. Recent Hughes studies indicate that from a cost standpoint the geosynchronous satellite (GEOS) is most economical, followed by the medium earth orbit satellite (MEOS) and then by the low earth orbit satellite (LEOS). From a system performance standpoint, this evaluation may be in reverse order, depending on how the public will react to speech delay and collision. This paper discusses the trends and various mobile satellite constellations in satellite communication under investigation. It considers the effect of orbital altitude and modulation/multiple access on the link and spacecraft design.

JPSS Preparations at the Satellite Proving Ground for Marine, Precipitation, and Satellite Analysis

Science.gov (United States)

Folmer, Michael J.; Berndt, E.; Clark, J.; Orrison, A.; Kibler, J.; Sienkiewicz, J.; Nelson, J.; Goldberg, M.; Sjoberg, W.

2016-01-01

The ocean prediction center at the national hurricane center's tropical analysis and forecast Branch, the Weather Prediction center and the Satellite analysis branch of NESDIS make up the Satellite Proving Ground for Marine, Precipitation and Satellite Analysis. These centers had early exposure to JPSS products using the S-NPP Satellite that was launched in 2011. Forecasters continue to evaluate new products in anticipation for the launch of JPSS-1 sometime in 2017.

Flight Dynamics Operations Management of the Large and Heterogeneous Eutelsat Fleet of Commercial Satellites

Science.gov (United States)

Bellido, E.

The EUTELSAT FDU (Flight Dynamics Unit) manages the resources to perform the typical activities of the large satellite operators and faces the usual difficulties raising from a vast and heterogeneous fleet. At present 20 satellites from 9 different platforms/sub-platforms are controlled from our Satellite Control Centre. The FDU was created in 2002 with the aim to respond to the operational needs of a growing fleet in terms of number of satellites and activities. It is at present composed of 6 engineering staff with the objective to provide operations service covering the whole lifecycle of the satellites from the procurement phase till the decommissioning. The most demanding activity is the daily operations, which must ensure maximum safety and continuity of service with the highest efficiency. Solutions have been applied from different areas: management, structure, operations organisation, processes, facilities, quality standards, etc. In addition to this, EUTELSAT is a growing communications operator and the FDU needs to contribute to the global objectives of the company. This paper covers our approach.

The satellite situation center

International Nuclear Information System (INIS)

Teague, M.J.; Sawyer, D.M.; Vette, J.I.

1982-01-01

Considerations related to the early planning for the International Magnetospheric Study (IMS) took into account the desirability of an establishment of specific entities for generating and disseminating coordination information for both retrospective and predictive periods. The organizations established include the IMS/Satellite Situation Center (IMS/SSC) operated by NASA. The activities of the SSC are related to the preparation of reports on predicted and actually achieved satellite positions, the response to inquiries, the compilation of information on satellite experiments, and the issue of periodic status summaries. Attention is given to high-altitude satellite services, other correlative satellite services, non-IMS activities of the SSC, a summary of the SSC request activity, and post-IMS and future activities

Plan of Time Management of Satellite Positioning System using Quasi-zenith Satellite

Science.gov (United States)

Takahashi, Yasuhiro; Fujieda, Miho; Amagai, Jun; Yokota, Shoichiro; Kimura, Kazuhiro; Ito, Hiroyuki; Hama, Shin'ichi; Morikawa, Takao; Kawano, Isao; Kogure, Satoshi

The Quasi-Zenith satellites System (QZSS) is developed as an integrated satellite service system of communication, broadcasting and positioning for mobile users in specified regions of Japan from high elevation angle. Purposes of the satellite positioning system using Quasi-Zenith satellite (QZS) are to complement and augment the GPS. The national institutes concerned have been developing the positioning system using QZS since 2003 and will carry out experiments and researches in three years after the launch. In this system, National Institute of Information and Communications Technology (NICT) is mainly in charge of timing system for the satellite positioning system using QZS, such as onboard hydrogen maser atomic clock and precise time management system of the QZSS. We started to develop the engineering model of the time management system for the QZSS. The time management system for the QZSS will be used to compare time differences between QZS and earth station as well as to compare between three onboard atomic clocks. This paper introduces time management of satellite positioning system using the QZSS.

Centralized Command, Distributed Control, and Decentralized Execution - a Command and Control Solution to US Air Force A2/AD Challenges

Science.gov (United States)

2017-04-28

backup or “retrograde” locations.61 The “low” portion of the design could be Control and Reporting Centers (CRCs), Airborne C2 platforms (e.g., E-3’s...technology and emerging capabilities must continue to be investigated (e.g., the “combat cloud ”).93 94 A2/AD is a dynamic family of problems that is...Report (Institute for Software Research, Carnegie Mellon University, Pittsburgh, PA: Center for the Computational Analysis of Social and

The EGSE science software of the IBIS instrument on-board INTEGRAL satellite

International Nuclear Information System (INIS)

La Rosa, Giovanni; Fazio, Giacomo; Segreto, Alberto; Gianotti, Fulvio; Stephen, John; Trifoglio, Massimo

2000-01-01

IBIS (Imager on Board INTEGRAL Satellite) is one of the key instrument on-board the INTEGRAL satellite, the follow up mission of the high energy missions CGRO and Granat. The EGSE of IBIS is composed by a Satellite Interface Simulator, a Control Station and a Science Station. Here are described the solutions adopted for the architectural design of the software running on the Science Station. Some preliminary results are used to show the science functionality, that allowed to understand the instrument behavior, all along the test and calibration campaigns of the Engineering Model of IBIS

Advancements of in-flight mass moment of inertia and structural deflection algorithms for satellite attitude simulators

Science.gov (United States)

Wright, Jonathan W.

Experimental satellite attitude simulators have long been used to test and analyze control algorithms in order to drive down risk before implementation on an operational satellite. Ideally, the dynamic response of a terrestrial-based experimental satellite attitude simulator would be similar to that of an on-orbit satellite. Unfortunately, gravitational disturbance torques and poorly characterized moments of inertia introduce uncertainty into the system dynamics leading to questionable attitude control algorithm experimental results. This research consists of three distinct, but related contributions to the field of developing robust satellite attitude simulators. In the first part of this research, existing approaches to estimate mass moments and products of inertia are evaluated followed by a proposition and evaluation of a new approach that increases both the accuracy and precision of these estimates using typical on-board satellite sensors. Next, in order to better simulate the micro-torque environment of space, a new approach to mass balancing satellite attitude simulator is presented, experimentally evaluated, and verified. Finally, in the third area of research, we capitalize on the platform improvements to analyze a control moment gyroscope (CMG) singularity avoidance steering law. Several successful experiments were conducted with the CMG array at near-singular configurations. An evaluation process was implemented to verify that the platform remained near the desired test momentum, showing that the first two components of this research were effective in allowing us to conduct singularity avoidance experiments in a representative space-like test environment.

System control and display

International Nuclear Information System (INIS)

Jacobs, J.

1977-01-01

The system described was designed, developed, and installed on short time scales and primarily utilized of-the-shelf military and commercial hardware. The system was designed to provide security-in-depth and multiple security options with several stages of redundancy. Under normal operating conditions, the system is computer controlled with manual backup during abnormal conditions. Sensor alarm data are processed in conjunction with weather data to reduce nuisance alarms. A structured approach is used to order alarmed sectors for assessment. Alarm and video information is presented to security personnel in an interactive mode. Historical operational data are recorded for system evaluation

The Future of Satellite Communications Technology.

Science.gov (United States)

Nowland, Wayne

1985-01-01

Discusses technical advances in satellite technology since the 1960s, and the International Telecommunications Satellite Organization's role in these developments; describes how AUSSAT, Australia's domestic satellite system, exemplifies the latest developments in satellite technology; and reviews satellite system features, possible future…

Jitter reduction of a reaction wheel by management of angular momentum using magnetic torquers in nano- and micro-satellites

Science.gov (United States)

Inamori, Takaya; Wang, Jihe; Saisutjarit, Phongsatorn; Nakasuka, Shinichi

2013-07-01

Nowadays, nano- and micro-satellites, which are smaller than conventional large satellites, provide access to space to many satellite developers, and they are attracting interest as an application of space development because development is possible over shorter time period at a lower cost. In most of these nano- and micro-satellite missions, the satellites generally must meet strict attitude requirements for obtaining scientific data under strict constraints of power consumption, space, and weight. In many satellite missions, the jitter of a reaction wheel degrades the performance of the mission detectors and attitude sensors; therefore, jitter should be controlled or isolated to reduce its effect on sensor devices. In conventional standard-sized satellites, tip-tilt mirrors (TTMs) and isolators are used for controlling or isolating the vibrations from reaction wheels; however, it is difficult to use these devices for nano- and micro-satellite missions under the strict power, space, and mass constraints. In this research, the jitter of reaction wheels is reduced by using accurate sensors, small reaction wheels, and slow rotation frequency reaction wheel instead of TTMs and isolators. The objective of a reaction wheel in many satellite missions is the management of the satellite's angular momentum, which increases because of attitude disturbances. If the magnitude of the disturbance is reduced in orbit or on the ground, the magnitude of the angular momentum that the reaction wheels gain from attitude disturbances in orbit becomes smaller; therefore, satellites can stabilize their attitude using only smaller reaction wheels or slow rotation speed, which cause relatively smaller vibration. In nano- and micro-satellite missions, the dominant attitude disturbance is a magnetic torque, which can be cancelled by using magnetic actuators. With the magnetic compensation, the satellite reduces the angular momentum that the reaction wheels gain, and therefore, satellites do

Cooperative and cognitive satellite systems

CERN Document Server

Chatzinotas, Symeon; De Gaudenzi, Riccardo

2015-01-01

Cooperative and Cognitive Satellite Systems provides a solid overview of the current research in the field of cooperative and cognitive satellite systems, helping users understand how to incorporate state-of-the-art communication techniques in innovative satellite network architectures to enable the next generation of satellite systems. The book is edited and written by top researchers and practitioners in the field, providing a comprehensive explanation of current research that allows users to discover future technologies and their applications, integrate satellite and terrestrial systems

Contrast in low-cost operational concepts for orbiting satellites

Science.gov (United States)

Walyus, Keith D.; Reis, James; Bradley, Arthur J.

2002-12-01

Older spacecraft missions, especially those in low Earth orbit with telemetry intensive requirements, required round-the-clock control center staffing. The state of technology relied on control center personnel to continually examine data, make decisions, resolve anomalies, and file reports. Hubble Space Telescope (HST) is a prime example of this description. Technological advancements in hardware and software over the last decade have yielded increases in productivity and operational efficiency, which result in lower cost. The re-engineering effort of HST, which has recently concluded, utilized emerging technology to reduce cost and increase productivity. New missions, of which NASA's Transition Region and Coronal Explorer Satellite (TRACE) is an example, have benefited from recent technological advancements and are more cost-effective than when HST was first launched. During its launch (1998) and early orbit phase, the TRACE Flight Operations Team (FOT) employed continually staffed operations. Yet once the mission entered its nominal phase, the FOT reduced their staffing to standard weekday business hours. Operations were still conducted at night and during the weekends, but these operations occurred autonomously without compromising their high standards for data collections. For the HST, which launched in 1990, reduced cost operations will employ a different operational concept, when the spacecraft enters its low-cost phase after its final servicing mission in 2004. Primarily due to the spacecraft"s design, the HST Project has determined that single-shift operations will introduce unacceptable risks for the amount of dollars saved. More importantly, significant cost-savings can still be achieved by changing the operational concept for the FOT, while still maintaining round-the-clock staffing. It"s important to note that the low-cost solutions obtained for one satellite may not be applicable for other satellites. This paper will contrast the differences between

Autonomous Satellite Command and Control Through the World Wide Web. Phase 3

Science.gov (United States)

Cantwell, Brian; Twiggs, Robert

1998-01-01

The Automated Space System Experimental Testbed (ASSET) system is a simple yet comprehensive real-world operations network being developed. Phase 3 of the ASSET Project was January-December 1997 and is the subject of this report. This phase permitted SSDL and its project partners to expand the ASSET system in a variety of ways. These added capabilities included the advancement of ground station capabilities, the adaptation of spacecraft on-board software, and the expansion of capabilities of the ASSET management algorithms. Specific goals of Phase 3 were: (1) Extend Web-based goal-level commanding for both the payload PI and the spacecraft engineer. (2) Support prioritized handling of multiple (PIs) Principle Investigators as well as associated payload experimenters. (3) Expand the number and types of experiments supported by the ASSET system and its associated spacecraft. (4) Implement more advanced resource management, modeling and fault management capabilities that integrate the space and ground segments of the space system hardware. (5) Implement a beacon monitoring test. (6) Implement an experimental blackboard controller for space system management. (7) Further define typical ground station developments required for Internet-based remote control and for full system automation of the PI-to-spacecraft link. Each of those goals are examined. Significant sections of this report were also published as a conference paper. Several publications produced in support of this grant are included as attachments. Titles include: 1) Experimental Initiatives in Space System Operations; 2) The ASSET Client Interface: Balancing High Level Specification with Low Level Control; 3) Specifying Spacecraft Operations At The Product/Service Level; 4) The Design of a Highly Configurable, Reusable Operating System for Testbed Satellites; 5) Automated Health Operations For The Sapphire Spacecraft; 6) Engineering Data Summaries for Space Missions; and 7) Experiments In Automated Health

Attitude Control and Orbital Dynamics Challenges of Removing the First 3-Axis Stabilized Tracking and Data Relay Satellite from the Geosynchronous ARC

Science.gov (United States)

Benet, Charles A.; Hofman, Henry; Williams, Thomas E.; Olney, Dave; Zaleski, Ronald

2011-01-01

Launched on April 4, 1983 onboard STS 6 (Space Shuttle Challenger), the First Tracking and Data Relay Satellite (TDRS 1) was retired above the Geosynchronous Orbit (GEO) on June 27, 2010 after having provided real-time communications with a variety of low-orbiting spacecraft over a 26-year period. To meet NASA requirements limiting orbital debris 1, a team of experts was assembled to conduct an End-Of-Mission (EOM) procedure to raise the satellite 350 km above the GEO orbit. Following the orbit raising via conventional station change maneuvers, the team was confronted with having to deplete the remaining propellant and passivate all energy storage or generation sources. To accomplish these tasks within the time window, communications (telemetry and control links), electrical power, propulsion, and thermal constraints, a spacecraft originally designed as a three-axis stabilized satellite was turned into a spinner. This paper (a companion paper to Innovative Approach Enabled the Retirement of TDRS 1, paper # 1699, IEEE 2011 Aerospace Conference, March 5-12, 2011 sup 2) focuses on the challenges of maintaining an acceptable spinning dynamics, while repetitively firing thrusters. Also addressed are the effects of thruster firings on the orbit characteristics and how they were mitigated by a careful scheduling of the fuel depletion operations. Periodic thruster firings for spin rate adjustment, nutation damping, and precession of the momentum vector were also required in order to maintain effective communications with the satellite. All operations were thoroughly rehearsed and supported by simulations thus lending a high level of confidence in meeting the NASA EOM goals.

A Software Implementation of a Satellite Interface Message Processor.

Science.gov (United States)

Eastwood, Margaret A.; Eastwood, Lester F., Jr.

A design for network control software for a computer network is described in which some nodes are linked by a communications satellite channel. It is assumed that the network has an ARPANET-like configuration; that is, that specialized processors at each node are responsible for message switching and network control. The purpose of the control…

Thematic mapping from satellite imagery

CERN Document Server

Denègre, J

2013-01-01

Thematic Mapping from Satellite Imagery: A Guidebook discusses methods in producing maps using satellite images. The book is comprised of five chapters; each chapter covers one stage of the process. Chapter 1 tackles the satellite remote sensing imaging and its cartographic significance. Chapter 2 discusses the production processes for extracting information from satellite data. The next chapter covers the methods for combining satellite-derived information with that obtained from conventional sources. Chapter 4 deals with design and semiology for cartographic representation, and Chapter 5 pre

Full Service ISDN Satellite (FSIS) network model for advanced ISDN satellite design and experiments

Science.gov (United States)

Pepin, Gerard R.

1992-01-01

The Full Service Integrated Services Digital Network (FSIS) network model for advanced satellite designs describes a model suitable for discrete event simulations. A top down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ACTS and the Interim Service ISDN Satellite (ISIS) perform ISDN protocol analyses and switching decisions in the terrestrial domain, whereas FSIS makes all its analyses and decisions on-board the ISDN satellite.

Magnetic field experiment on the SUNSAT satellite

Science.gov (United States)

Kotzé, P. B.; Langenhoven, B.; Risbo, T.

2002-03-01

On Tuesday 23 February 1999, at 10:29 UTC, SUNSAT was launched into an 857×655 km, 96.47° polar orbit on a Boeing-Delta II rocket from Vandenberg Air Force Base in California, USA. Both SUNSAT and Ørsted were NASA-sponsored secondary payloads accompanying the USA Air Force Argos satellite. In the process it became South Africa's (and Africa's) first satellite in space. Although sponsored by several private industrial organisations, it is essentially a student project with more than 96 graduate students in the Department of Electronic and Electrical Engineering at the University of Stellenbosch providing the majority of SUNSAT's engineering development and operation since 1992. This paper reports on the magnetic field experiment on board the Sunsat satellite, consisting of two fluxgate magnetometers, called Orimag and Scimag, both built and calibrated by the Hermanus Magnetic Observatory. Orimag is mainly used for orientation control purposes on SUNSAT, while Scimag, mounted on a boom of 2.2 m is designed to perform geomagnetic field observations, employing standard navigation fluxgate technology.

Fiber optical sensing on-board communication satellites

Science.gov (United States)

Hurni, A.; Lemke, N. M. K.; Roner, M.; Obermaier, J.; Putzer, P.; Kuhenuri Chami, N.

2017-11-01

Striving constantly to reduce mass, AIT effort and overall cost of the classical point-to-point wired temperature sensor harness on-board telecommunication satellites, OHB System (formerly Kayser-Threde) has introduced the Hybrid Sensor Bus (HSB) system. As a future spacecraft platform element, HSB relies on electrical remote sensor units as well as fiber-optical sensors, both of which can serially be connected in a bus architecture. HSB is a modular measurement system with many applications, also thanks to the opportunities posed by the digital I²C bus. The emphasis, however, is on the introduction of fiber optics and especially fiber-Bragg grating (FBG) temperature sensors as disruptive innovation for the company's satellite platforms. The light weight FBG sensors are directly inscribed in mechanically robust and radiation tolerant fibers, reducing the need for optical fiber connectors and splices to a minimum. Wherever an FBG sensor shall be used, the fiber is glued together with a corresponding temperature transducer to the satellites structure or to a subsystem. The transducer is necessary to provide decoupling of mechanical stress, but simultaneously ensure a high thermal conductivity. HSB has been developed in the frame of an ESA-ARTES program with European and German co-funding and will be verified as flight demonstrator on-board the German Heinrich Hertz satellite (H2Sat). In this paper the Engineering Model development of HSB is presented and a Fiber-optical Sensor Multiplexer for a more flexible sensor bus architecture is introduced. The HSB system aims at telecommunication satellite platforms with an operational life time beyond 15 years in geostationary orbit. It claims a high compatibility in terms of performance and interfaces with existing platforms while it was designed with future applications with increased radiation exposure already in mind. In its basic configuration HSB consists of four modules which are the Power Supply Unit, the HSB

Polar-Orbiting Satellite (POES) Images

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from camera systems or radiometer instruments on satellites in orbit around the poles. Satellite campaigns include...

The Eccentric Satellites Problem: Comparing Milky Way Satellite Orbital Properties to Simulation Results

Science.gov (United States)

Haji, Umran; Pryor, Carlton; Applebaum, Elaad; Brooks, Alyson

2018-01-01

We compare the orbital properties of the satellite galaxies of the Milky Way to those of satellites found in simulated Milky Way-like systems as a means of testing cosmological simulations of galaxy formation. The particular problem that we are investigating is a discrepancy in the distribution of orbital eccentricities. Previous studies of Milky Way-mass systems analyzed in a semi-analytic ΛCDM cosmological model have found that the satellites tend to have significantly larger fractions of their kinetic energy invested in radial motion with respect to their central galaxy than do the real-world Milky Way satellites. We analyze several high-resolution ("zoom-in") hydrodynamical simulations of Milky Way-mass galaxies and their associated satellite systems to investigate why previous works found Milky Way-like systems to be rare. We find a possible relationship between a quiescent galactic assembly history and a distribution of satellite kinematics resembling that of the Milky Way. This project has been supported by funding from National Science Foundation grant PHY-1560077.

Myostatin signals through Pax7 to regulate satellite cell self-renewal

International Nuclear Information System (INIS)

McFarlane, Craig; Hennebry, Alex; Thomas, Mark; Plummer, Erin; Ling, Nicholas; Sharma, Mridula; Kambadur, Ravi

2008-01-01

Myostatin, a Transforming Growth Factor-beta (TGF-β) super-family member, has previously been shown to negatively regulate satellite cell activation and self-renewal. However, to date the mechanism behind Myostatin function in satellite cell biology is not known. Here we show that Myostatin signals via a Pax7-dependent mechanism to regulate satellite cell self-renewal. While excess Myostatin inhibited Pax7 expression via ERK1/2 signaling, an increase in Pax7 expression was observed following both genetic inactivation and functional antagonism of Myostatin. As a result, we show that either blocking or inactivating Myostatin enhances the partitioning of the fusion-incompetent self-renewed satellite cell lineage (high Pax7 expression, low MyoD expression) from the pool of actively proliferating myogenic precursor cells. Consistent with this result, over-expression of Pax7 in C2C12 myogenic cells resulted in increased self-renewal through a mechanism which slowed both myogenic proliferation and differentiation. Taken together, these results suggest that increased expression of Pax7 promotes satellite cell self-renewal, and furthermore Myostatin may control the process of satellite cell self-renewal through regulation of Pax7. Thus we speculate that, in addition to the intrinsic factors (such as Pax7), extrinsic factors both positive and negative in nature, will play a major role in determining the stemness of skeletal muscle satellite cells

Partnership via Satellite.

Science.gov (United States)

Powell, Marie Clare

1980-01-01

Segments of the 1980 National Catholic Educational Association (NCEA) conference were to be telecast nationally by satellite. The author briefly explains the satellite transmission process and advises Catholic educators on how to pick up the broadcast through their local cable television system. (SJL)

A new cellular stress response that triggers centriolar satellite reorganization and ciliogenesis

DEFF Research Database (Denmark)

Villumsen, Bine H; Danielsen, Jannie R; Povlsen, Lou

2013-01-01

uncover a new two-pronged signalling response, which by coupling p38-dependent phosphorylation with MIB1-catalysed ubiquitylation of ciliogenesis-promoting factors plays an important role in controlling centriolar satellite status and key centrosomal functions in a cell stress-regulated manner.......Centriolar satellites are small, granular structures that cluster around centrosomes, but whose biological function and regulation are poorly understood. We show that centriolar satellites undergo striking reorganization in response to cellular stresses such as UV radiation, heat shock......, and transcription blocks, invoking acute and selective displacement of the factors AZI1/CEP131, PCM1, and CEP290 from this compartment triggered by activation of the stress-responsive kinase p38/MAPK14. We demonstrate that the E3 ubiquitin ligase MIB1 is a new component of centriolar satellites, which interacts...

A framework for back-up and restore under the Experimental Physics and Industrial Control System

International Nuclear Information System (INIS)

Karonis, N.T.

1992-12-01

EPICS is a system that allows one to design and implement a controls system. At its foundation, i.e., the level closest to the devices being controlled, are autonomous computers, each called an Input/Output Controller or IOC. In EPICS, devices controlled by an IOC are represented by software entities called process variables. All devices are monitored/controlled by reading/writing values from/to their associated process variables. Under this schema, distributing processing over a number of IOCs and representing devices with process variables, there are a variety of ways one can view or group the information in the control system. Two of the more common groupings are by IOC (location) and by devices (function). Simply stated, the authors require a system capable of restoring the state of the machine, in their case the Advanced Photon Source, to a known desired state from somewhere in the past. To that end, they propose a framework which describes a system that periodically records and preserves the values of key process variables so that later on, those values can be written to the machine in an attempt to restore it to that same state. One of the more powerful notions that must be preserved in any system that solves this problem is the independence between the specification of what is monitored and the specification of what is written. In other words, grouping process variables for monitoring must be kept independent of the number of different ways to group process variables (e.g., by IOC, by device, etc.) when they are written

Integration of an ion engine on the Communications Technology Satellite.

Science.gov (United States)

Payne, W. F.; Finke, R. C.

1972-01-01

An ion engine subsystem intended for satellite stationkeeping tasks is described. Ion thrusters are chosen to perform the task because the specific impulse is at least an order of magnitude higher than the commonly used reaction control jets. The higher the value of specific impulse, the greater the total impulse that can be attained for a given weight of propellant, hence cost benefits result. The integration, subsystem testing, and the operating plans for the ion engine experiment to be flown in 1975 on the Canadian Communications Technology Satellite (CTS) are described. The subsystem is designed to demonstrate north-south stationkeeping, attitude control by means of thrust vectoring, long-term space storage and restart capability, and compatibility with a high powered communications transponder.

An airborne meteorological data collection system using satellite relay /ASDAR/

Science.gov (United States)

Bagwell, J. W.; Lindow, B. G.

1978-01-01

The paper describes the aircraft to satellite data relay (ASDAR) project which processes information collected by the navigation and data systems of widebody jet aircraft which cross data-sparse areas of the tropics and southern hemisphere. The ASDAR system consists of a data acquisition and control unit to acquire, store, and format latitude, longitude, altitude, wind speed, wind direction, and outside air temperature data; a transmitter to relay the formatted data via satellite to the ground; and a clock to time the data sampling and transmission periods.

Interim Service ISDN Satellite (ISIS) hardware experiment development for advanced ISDN satellite designs and experiments

Science.gov (United States)

Pepin, Gerard R.

1992-01-01

The Interim Service Integrated Service Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Development for Advanced Satellite Designs describes the development of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into Time Division Multiple Access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the RS-499 interface for satellite uplink. The same ISTA converts in the opposite direction the RS-499 to U-interface data with a simple switch setting.

Interim Service ISDN Satellite (ISIS) hardware experiment design for advanced ISDN satellite design and experiments

Science.gov (United States)

Pepin, Gerard R.

1992-01-01

The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Hardware Experiment Design for Advanced Satellite Designs describes the design of the ISDN Satellite Terminal Adapter (ISTA) capable of translating ISDN protocol traffic into time division multiple access (TDMA) signals for use by a communications satellite. The ISTA connects the Type 1 Network Termination (NT1) via the U-interface on the line termination side of the CPE to the V.35 interface for satellite uplink. The same ISTA converts in the opposite direction the V.35 to U-interface data with a simple switch setting.

Backup_of_journaldec 2009

African Journals Online (AJOL)

and the problems faced at the operational level of TB control in Ekiti State. Methods:The ... Ten Local. Government Areas (LGA) out of the 16 LGAs in the state, selected by simple ... Therefore periodic evaluation of from participants was maintained. Data was the success and ... integrated into the primary health care services.

Changing inclination of earth satellites using the gravity of the moon

Directory of Open Access Journals (Sweden)

Karla de Souza Torres

2006-01-01

Full Text Available We analyze the problem of the orbital control of an Earth's satellite using the gravity of the Moon. The main objective is to study a technique to decrease the fuel consumption of a plane change maneuver to be performed in a satellite that is in orbit around the Earth. The main idea of this approach is to send the satellite to the Moon using a single-impulsive maneuver, use the gravity field of the Moon to make the desired plane change of the trajectory, and then return the satellite to its nominal semimajor axis and eccentricity using a bi-impulsive Hohmann-type maneuver. The satellite is assumed to start in a Keplerian orbit in the plane of the lunar orbit around the Earth and the goal is to put it in a similar orbit that differs from the initial orbit only by the inclination. A description of the close-approach maneuver is made in the three-dimensional space. Analytical equations based on the patched conics approach are used to calculate the variation in velocity, angular momentum, energy, and inclination of the satellite. Then, several simulations are made to evaluate the savings involved. The time required by those transfers is also calculated and shown.

Protocol and Topology Issues for Wide-Area Satellite Interconnection of Terrestrial Optical LANs

Science.gov (United States)

Parraga, N.

2002-01-01

system for multimedia services. EuroSkyWay uses a GEO satellite with onboard switching. It has its own proprietary protocol stack for data link control (DLC), logical link control (LLC) and layer 3 functions such as resource management, call admission control and authentication. Special attention is paid to the IP interworking with Layer 3 function since IP does not support connection set-up and session protocols, thus proper interworking functions with IP signaling protocols for resource reservation routing such as RSVP, BGP, and ICMP need to be developed. Whereas the EuroSkyWay system is an representative for a meshed topology, DVB-RCS systems have usually star configuration with a central hub station. Different data streams are distinguished by program identifiers (PIDs). Recent proposals aim at the evolution of DVB-RCS towards a fully meshed structure. The paper will also discuss the protocol architecture for interconnect SONET LANs over these systems. Finally, a performance comparison of the different solutions will be given in terms of cell overhead rate and signalling effort for selected scenarios.

The Skeletal Muscle Satellite Cell

Science.gov (United States)

2011-01-01

The skeletal muscle satellite cell was first described and named based on its anatomic location between the myofiber plasma and basement membranes. In 1961, two independent studies by Alexander Mauro and Bernard Katz provided the first electron microscopic descriptions of satellite cells in frog and rat muscles. These cells were soon detected in other vertebrates and acquired candidacy as the source of myogenic cells needed for myofiber growth and repair throughout life. Cultures of isolated myofibers and, subsequently, transplantation of single myofibers demonstrated that satellite cells were myogenic progenitors. More recently, satellite cells were redefined as myogenic stem cells given their ability to self-renew in addition to producing differentiated progeny. Identification of distinctively expressed molecular markers, in particular Pax7, has facilitated detection of satellite cells using light microscopy. Notwithstanding the remarkable progress made since the discovery of satellite cells, researchers have looked for alternative cells with myogenic capacity that can potentially be used for whole body cell-based therapy of skeletal muscle. Yet, new studies show that inducible ablation of satellite cells in adult muscle impairs myofiber regeneration. Thus, on the 50th anniversary since its discovery, the satellite cell’s indispensable role in muscle repair has been reaffirmed. PMID:22147605

Analytical solution of perturbed relative motion: an application of satellite formations to geodesy

Science.gov (United States)

Wnuk, Edwin

In the upcoming years, several space missions will be operated using a number of spacecraft flying in formation. Clusters of spacecraft with a carefully designed orbits and optimal formation geometry enable a wide variety of applications ranging from remote sensing to astronomy, geodesy and basic physics. Many of the applications require precise relative navigation and autonomous orbit control of satellites moving in a formation. For many missions a centimeter level of orbit control accuracy is required. The GRACE mission, since its launch in 2002, has been improving the Earth's gravity field model to a very high level of accuracy. This mission is a formation flying one consisting of two satellites moving in coplanar orbits and provides range and range-rate measurements between the satellites in the along-track direction. Future geodetic missions probably will employ alternative architectures using additional satellites and/or performing out-of-plane motion, e.g cartwheel orbits. The paper presents an analytical model of a satellite formation motion that enables propagation of the relative spacecraft motion. The model is based on the analytical theory of satellite relative motion that was presented in the previous our papers (Wnuk and Golebiewska, 2005, 2006). This theory takes into account the influence of the following gravitational perturbation effects: 1) zonal and tesseral harmonic geopotential coefficients up to arbitrary degree and order, 2) Lunar gravity, 3) Sun gravity. Formulas for differential perturbations were derived with any restriction concerning a plane of satellite orbits. They can be applied in both: in plane and out of plane cases. Using this propagator we calculated relative orbits and future relative satellite positions for different types of formations: in plane, out of plane, cartwheel and others. We analyzed the influence of particular parts of perturbation effects and estimated the accuracy of predicted relative spacecrafts positions

A Mobile Satellite Experiment (MSAT-X) network definition

Science.gov (United States)

Wang, Charles C.; Yan, Tsun-Yee

1990-01-01

The network architecture development of the Mobile Satellite Experiment (MSAT-X) project for the past few years is described. The results and findings of the network research activities carried out under the MSAT-X project are summarized. A framework is presented upon which the Mobile Satellite Systems (MSSs) operator can design a commercial network. A sample network configuration and its capability are also included under the projected scenario. The Communication Interconnection aspect of the MSAT-X network is discussed. In the MSAT-X network structure two basic protocols are presented: the channel access protocol, and the link connection protocol. The error-control techniques used in the MSAT-X project and the packet structure are also discussed. A description of two testbeds developed for experimentally simulating the channel access protocol and link control protocol, respectively, is presented. A sample network configuration and some future network activities of the MSAT-X project are also presented.

Piloted simulation tests of propulsion control as backup to loss of primary flight controls for a mid-size jet transport

Science.gov (United States)

Bull, John; Mah, Robert; Davis, Gloria; Conley, Joe; Hardy, Gordon; Gibson, Jim; Blake, Matthew; Bryant, Don; Williams, Diane

1995-01-01

Failures of aircraft primary flight-control systems to aircraft during flight have led to catastrophic accidents with subsequent loss of lives (e.g. , DC-1O crash, B-747 crash, C-5 crash, B-52 crash, and others). Dryden Flight Research Center (DFRC) investigated the use of engine thrust for emergency flight control of several airplanes, including the B-720, Lear 24, F-15, C-402, and B-747. A series of three piloted simulation tests have been conducted at Ames Research Center to investigate propulsion control for safely landing a medium size jet transport which has experienced a total primary flight-control failure. The first series of tests was completed in July 1992 and defined the best interface for the pilot commands to drive the engines. The second series of tests was completed in August 1994 and investigated propulsion controlled aircraft (PCA) display requirements and various command modes. The third series of tests was completed in May 1995 and investigated PCA full-flight envelope capabilities. This report describes the concept of a PCA, discusses pilot controls, displays, and procedures; and presents the results of piloted simulation evaluations of the concept by a cross-section of air transport pilots.

Telelibrary: Library Services via Satellite.

Science.gov (United States)

Liu, Rosa

1979-01-01

Investigates the provision of library services via satellite, explains briefly the operation and advantages of communication satellites, and discusses the various telecommunications equipment and services which, when coupled with satellite transmission, will enhance library activities. Demand trend projections for telecommunications services…

RELATIVE ORIENTATION AND MODIFIED PIECEWISE EPIPOLAR RESAMPLING FOR HIGH RESOLUTION SATELLITE IMAGES

Directory of Open Access Journals (Sweden)

K. Gong

2017-05-01

Full Text Available High resolution, optical satellite sensors are boosted to a new era in the last few years, because satellite stereo images at half meter or even 30cm resolution are available. Nowadays, high resolution satellite image data have been commonly used for Digital Surface Model (DSM generation and 3D reconstruction. It is common that the Rational Polynomial Coefficients (RPCs provided by the vendors have rough precision and there is no ground control information available to refine the RPCs. Therefore, we present two relative orientation methods by using corresponding image points only: the first method will use quasi ground control information, which is generated from the corresponding points and rough RPCs, for the bias-compensation model; the second method will estimate the relative pointing errors on the matching image and remove this error by an affine model. Both methods do not need ground control information and are applied for the entire image. To get very dense point clouds, the Semi-Global Matching (SGM method is an efficient tool. However, before accomplishing the matching process the epipolar constraints are required. In most conditions, satellite images have very large dimensions, contrary to the epipolar geometry generation and image resampling, which is usually carried out in small tiles. This paper also presents a modified piecewise epipolar resampling method for the entire image without tiling. The quality of the proposed relative orientation and epipolar resampling method are evaluated, and finally sub-pixel accuracy has been achieved in our work.

Milestones in screen-based process control

International Nuclear Information System (INIS)

Guesnier, G.P.

1995-01-01

The German approach is based on the utilisation of the conceptual elements of the PRISCA information system developed by Siemens and on operational experience with screen-based process control in a conventional power plant. In the French approach, the screen-based control room for the N4 plants, designed from scratch, has undergone extensive simulator tests for validation before going into realisation. It is now used in the commissioning phase of the first N4 plants. The design of the control room for the European Pressurized Water Reactor will be based on the common experience of Siemens and Electricite de France. Its main elements are several separate operator workstations, a safety control area used as a back-up for postulated failures of the workstations, and a commonly utilisable plant overview for the operators' coordination. (orig./HP) [de

Auto Mission Planning System Design for Imaging Satellites and Its Applications in Environmental Field

Directory of Open Access Journals (Sweden)

He Yongming

2016-10-01

Full Text Available Satellite hardware has reached a level of development that enables imaging satellites to realize applications in the area of meteorology and environmental monitoring. As the requirements in terms of feasibility and the actual profit achieved by satellite applications increase, we need to comprehensively consider the actual status, constraints, unpredictable information, and complicated requirements. The management of this complex information and the allocation of satellite resources to realize image acquisition have become essential for enhancing the efficiency of satellite instrumentation. In view of this, we designed a satellite auto mission planning system, which includes two sub-systems: the imaging satellite itself and the ground base, and these systems would then collaborate to process complicated missions: the satellite mainly focuses on mission planning and functions according to actual parameters, whereas the ground base provides auxiliary information, management, and control. Based on the requirements analysis, we have devised the application scenarios, main module, and key techniques. Comparison of the simulation results of the system, confirmed the feasibility and optimization efficiency of the system framework, which also stimulates new thinking for the method of monitoring environment and design of mission planning systems.

The ecology of malaria--as seen from Earth-observation satellites.

Science.gov (United States)

Thomson, M C; Connor, S J; Milligan, P J; Flasse, S P

1996-06-01

Data from sensors on board geostationary and polar-orbiting, meteorological satellites (Meteosat and NOAA series) are routinely obtained free, via local reception systems, in an increasing number of African countries. Data collected by these satellites are processed to produce proxy ecological variables which have been extensively investigated for monitoring changes in the distribution and condition of different natural resources, including rainfall and vegetation state. How these data products (once incorporated, along with other data, into a geographical information system) could contribute to the goals of monitoring patterns of malaria transmission, predicting epidemics and planning control strategies is the subject of the present review. By way of illustration, an analysis of two of these products, normalized difference vegetation index (NVDI) and cold-cloud duration (CCD), is given in conjunction with epidemiological and entomological data from The Gambia, a country where extensive studies on malaria transmission have been undertaken in recent years. Preliminary results indicate that even simple analysis of proxy ecological variables derived from satellite data can indicate variation in environmental factors affecting malaria-transmission indices. However, it is important to note that the associations observed will vary depending on the local ecology, season and species of vector. Whilst further quantitative research is required to validate the relationship between satellite-data products and malaria-transmission indices, this approach offers a means by which detailed knowledge of the underlying spatial and temporal variation in the environment can be incorporated into a decision-support system for malaria control.

An evolutionary framework for the Jovian and Saturnian satellites

International Nuclear Information System (INIS)

Stevenson, R.J.

1987-01-01

The position of the satellite within the protonebula, the influence of the parent planet, particularly the relative effects of tidal (gravitational) as opposed to radiogenic (internal) heat generating processes, as well as the type of ice, exert a control on the evolutionary histories of the Jovian and Saturnian satellites. The landscapes of the moons are modified by surface deformational processes (tectonic activity derived from within the body) and externally derived cratering. The geological history of the Galilean satellites is deduced from surface stratigraphic successions of geological units. Io and Europa, with crater-free surfaces, are tectonically more advanced than crater-saturated Callisto. Two thermal-drive models are proposed based on: an expression for externally derived gravitational influences between two bodies; and internal heat generation via radiogenic decay (expressed by surface area/volume ratio). Both parameters, for the Galilean satellites, are plotted against an inferred product of tectonic processes - the age of the surface terrain. From these diagrams, the tectonic evolutionary state of the more distant Saturnian system are predicted. These moons are fitted into an evolutionary framework for the Solar System. 34 refs.; 4 figs.; 2 tabs

Activities of Canadian Satellite Communications, Inc.

Science.gov (United States)

1992-12-01

Canadian Satellite Communications (Cancom) has as its core business the provision of television and radio signals to cable systems in Canada, with the objective of making affordable broadcast signals available to remote and/or small communities. Cancom also provides direct-to-home services to backyard receiving dishes, as well as satellite digital data business communications services, satellite business television, and satellite network services. Its business communication services range from satellite links for big-city businesses with small branch operations located far from major centers, to a mobile messaging and tracking system for the trucking industry. Revenues in 1992 totalled $48,212,000 and net income was just over $7 million. Cancom bought 10 percent interest in Leosat Corp. of Washington, DC, who are seeking approval to operate a position locator network from low-orbit satellites. Cancom has also become a partner in SovCan Star Satellite Communications Inc., which will build an international satellite system in partnership with Russia. The first satellite in this east-west business network will be placed in a Russian orbital slot over the Atlantic by 1996, and a second satellite will follow for the Pacific region. This annual report of Cancom's activities for 1992 includes financial statements and a six year financial review.

Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Actuators and Sensors

DEFF Research Database (Denmark)

Baldi, P.; Blanke, Mogens; Castaldi, P.

2016-01-01

This paper presents a novel scheme for diagnosis of faults affecting the sensors measuring the satellite attitude, body angular velocity and flywheel spin rates as well as defects related to the control torques provided by satellite reaction wheels. A nonlinear geometric design is used to avoid t...

Maui Space Surveillance System Satellite Categorization Laboratory

Science.gov (United States)

Deiotte, R.; Guyote, M.; Kelecy, T.; Hall, D.; Africano, J.; Kervin, P.

The MSSS satellite categorization laboratory is a fusion of robotics and digital imaging processes that aims to decompose satellite photometric characteristics and behavior in a controlled setting. By combining a robot, light source and camera to acquire non-resolved images of a model satellite, detailed photometric analyses can be performed to extract relevant information about shape features, elemental makeup, and ultimately attitude and function. Using the laboratory setting a detailed analysis can be done on any type of material or design and the results cataloged in a database that will facilitate object identification by "curve-fitting" individual elements in the basis set to observational data that might otherwise be unidentifiable. Currently the laboratory has created, an ST-Robotics five degree of freedom robotic arm, collimated light source and non-focused Apogee camera have all been integrated into a MATLAB based software package that facilitates automatic data acquisition and analysis. Efforts to date have been aimed at construction of the lab as well as validation and verification of simple geometric objects. Simple tests on spheres, cubes and simple satellites show promising results that could lead to a much better understanding of non-resolvable space object characteristics. This paper presents a description of the laboratory configuration and validation test results with emphasis on the non-resolved photometric characteristics for a variety of object shapes, spin dynamics and orientations. The future vision, utility and benefits of the laboratory to the SSA community as a whole are also discussed.

JPSS Preparations at the Satellite Proving Ground for Marine, Precipitation, and Satellite Analysis

Science.gov (United States)

Folmer, M. J.; Berndt, E.; Clark, J.; Orrison, A.; Kibler, J.; Sienkiewicz, J. M.; Nelson, J. A., Jr.; Goldberg, M.

2016-12-01

The National Oceanic and Atmospheric Administration (NOAA) Satellite Proving Ground (PG) for Marine, Precipitation, and Satellite Analysis (MPS) has been demonstrating and evaluating Suomi National Polar-orbiting Partnership (S-NPP) products along with other polar-orbiting satellite platforms in preparation for the Joint Polar Satellite System - 1 (JPSS-1) launch in March 2017. The first S-NPP imagery was made available to the MPS PG during the evolution of Hurricane Sandy in October 2012 and has since been popular in operations. Since this event the MPS PG Satellite Liaison has been working with forecasters on ways to integrate single-channel and multispectral imagery from the Visible Infrared Imaging Radiometer Suite (VIIRS), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Advanced Very High Resolution Radiometer (AVHRR)into operations to complement numerical weather prediction and geostationary satellite savvy National Weather Service (NWS) National Centers. Additional unique products have been introduced to operations to address specific forecast challenges, including the Cooperative Institute for Research in the Atmosphere (CIRA) Layered Precipitable Water, the National Environmental Satellite, Data, and Information Service (NESDIS) Snowfall Rate product, NOAA Unique Combined Atmospheric Processing System (NUCAPS) Soundings, ozone products from the Atmospheric Infrared Sounder (AIRS), Cross-track Infrared Sounder/Advanced Technology Microwave Sounder (CrIS/ATMS), and Infrared Atmospheric Sounding Interferometer (IASI). In addition, new satellite domains have been created to provide forecasters at the NWS Ocean Prediction Center and Weather Prediction Center with better quality imagery at high latitudes. This has led to research projects that are addressing forecast challenges such as tropical to extratropical transition and explosive cyclogenesis. This presentation will provide examples of how the MPS PG has been introducing and integrating

Satellite services system overview

Science.gov (United States)

Rysavy, G.

1982-01-01

The benefits of a satellite services system and the basic needs of the Space Transportation System to have improved satellite service capability are identified. Specific required servicing equipment are discussed in terms of their technology development status and their operative functions. Concepts include maneuverable television systems, extravehicular maneuvering unit, orbiter exterior lighting, satellite holding and positioning aid, fluid transfer equipment, end effectors for the remote manipulator system, teleoperator maneuvering system, and hand and power tools.

Data Collection Satellite Application in Precision Agriculture

Science.gov (United States)

Durào, O.

2002-01-01

Agricultural Instrumentation Research Center, Brazilian Agricultural Research Corporation; Space Programs Brazil launched in 1993 its first satellite partially built and entirely designed, integrated, tested and operated in the country. It was the SCD-1 satellite, a small (115 kg. and an octagonal prism with 80 cm. height and an external diameter of 100 cm.) with a payload transponder that receives data from ground platforms spread all over the country (including its sea shore). These data are then retransmitted to a receiving station at every satellite pass. Data collected and received are processed at Data Collection Mission Center for distribution via internet at most 30 min after the satellite pass. The ground platforms are called PCD's and differ in the parameters measured according to its purpose and location. Thus, they are able to measure temperature, rain level, wind direction, solar radiation, carbon monoxide as well as many others, beyond its own location. SCD- 1 had a nominal designed life of one year, but is still functioning. It is a LEO satellite with inclination of 25°. In 1998, the country launched SCD-2, with the same purpose, but in phase with SCD-1 . Other differences were a higher index of Brazilian made components and an active attitude control subsystem for the spin rate provided by the magnetic torque coils (these in accordance with a development strategy previously planned). In 1999 the country launched in cooperation with China a remote sensing satellite (mass of 1.4 ton.) called CBERS-1. This satellite is sun synchronous (98° inclination) and also carries a transponder for data collection/transmission as a secondary payload. Thus, the country has now three satellites with data collection/transmission capabilities, two in low inclination phased orbits and one in polar orbit, providing a nice coverage both geographical and temporal not only to its territory but also to other regions of the world.. At first there were not too many PCD

Mobility management in satellite networks

Science.gov (United States)

Johanson, Gary A.

1995-01-01

This paper addresses the methods used or proposed for use in multi-beam and/or multi-satellite networks designed to provide Mobile Satellite Services (MSS). Specific topics include beam crossover in the North American Mobile Satellite (MSAT) system as well as registration and live call hand-off for a multi-regional geosynchronous (GEO) satellite based system and a global coverage Low Earth Orbiting (LEO) system. In the MSAT system, the individual satellite beams cover very large geographic areas so the need for live call hand-off was not anticipated. This paper discusses the methods used to keep track of the beam location of the users so that incoming call announcements or other messages may be directed to them. Proposed new GEO systems with large numbers of beams will provide much smaller geographic coverage in individual beams and thus the need arises to keep track of the user's location as well as to provide live call hand-off as the user traverses from beam to beam. This situation also occurs in proposed LEO systems where the problems are worsened by the need for satellite to satellite hand-off as well as beam to beam hand-off within a single satellite. The paper discusses methods to accomplish these handoffs and proposes system architectures to address the various hand-off scenarios.

Configurable software for satellite graphics

Energy Technology Data Exchange (ETDEWEB)

Hartzman, P D

1977-12-01

An important goal in interactive computer graphics is to provide users with both quick system responses for basic graphics functions and enough computing power for complex calculations. One solution is to have a distributed graphics system in which a minicomputer and a powerful large computer share the work. The most versatile type of distributed system is an intelligent satellite system in which the minicomputer is programmable by the application user and can do most of the work while the large remote machine is used for difficult computations. At New York University, the hardware was configured from available equipment. The level of system intelligence resulted almost completely from software development. Unlike previous work with intelligent satellites, the resulting system had system control centered in the satellite. It also had the ability to reconfigure software during realtime operation. The design of the system was done at a very high level using set theoretic language. The specification clearly illustrated processor boundaries and interfaces. The high-level specification also produced a compact, machine-independent virtual graphics data structure for picture representation. The software was written in a systems implementation language; thus, only one set of programs was needed for both machines. A user can program both machines in a single language. Tests of the system with an application program indicate that is has very high potential. A major result of this work is the demonstration that a gigantic investment in new hardware is not necessary for computing facilities interested in graphics.

Miniaurizable, High Performance, Fiber-Optic Gyroscopes for Small Satellites, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Small satellites require much lighter weight, smaller, and long life Attitude control components that can withstand stressing launch conditions and space vibration...

Satellite-Based Sunshine Duration for Europe

Directory of Open Access Journals (Sweden)

Bodo Ahrens

2013-06-01

Full Text Available In this study, two different methods were applied to derive daily and monthly sunshine duration based on high-resolution satellite products provided by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT Satellite Application Facility on Climate Monitoring using data from Meteosat Second Generation (MSG SEVIRI (Spinning Enhanced Visible and Infrared Imager. The satellite products were either hourly cloud type or hourly surface incoming direct radiation. The satellite sunshine duration estimates were not found to be significantly different using the native 15-minute temporal resolution of SEVIRI. The satellite-based sunshine duration products give additional spatial information over the European continent compared with equivalent in situ-based products. An evaluation of the satellite sunshine duration by product intercomparison and against station measurements was carried out to determine their accuracy. The satellite data were found to be within ±1 h/day compared to high-quality Baseline Surface Radiation Network or surface synoptic observations (SYNOP station measurements. The satellite-based products differ more over the oceans than over land, mainly because of the treatment of fractional clouds in the cloud type-based sunshine duration product. This paper presents the methods used to derive the satellite sunshine duration products and the performance of the different retrievals. The main benefits and disadvantages compared to station-based products are also discussed.

Pilot simulation tests of propulsion control as backup to loss of primary flight controls for a mid-size jet transport

Science.gov (United States)

1995-12-01

Partial failures of aircraft primary flight-control systems and structural : damages to aircraft during flight have led to catastrophic accidents with : subsequent loss of life. These accidents can be prevented if sufficient : alternate control autho...

Encryption protection for communication satellites

Science.gov (United States)

Sood, D. R.; Hoernig, O. W., Jr.

In connection with the growing importance of the commercial communication satellite systems and the introduction of new technological developments, users and operators of these systems become increasingly concerned with aspects of security. The user community is concerned with maintaining confidentiality and integrity of the information being transmitted over the satellite links, while the satellite operators are concerned about the safety of their assets in space. In response to these concerns, the commercial satellite operators are now taking steps to protect the communication information and the satellites. Thus, communication information is being protected by end-to-end encryption of the customer communication traffic. Attention is given to the selection of the NBS DES algorithm, the command protection systems, and the communication protection systems.

Essential Technology and Application of Jitter Detection and Compensation for High Resolution Satellites

Directory of Open Access Journals (Sweden)

TONG Xiaohua

2017-10-01

Full Text Available Satellite jitter is a common and complex phenomenon for the on-orbit high resolution satellites, which may affect the mapping accuracy and quality of imagery. A framework of jitter detection and compensation integrating data processing of multiple sensors is proposed in this paper. Jitter detection is performed based on multispectral imagery, three-line-array imagery, dense ground control and attitude measurement data, and jitter compensation is conducted both on image and on attitude with the sensor model. The platform jitter of ZY-3 satellite is processed and analyzed using the proposed technology, and the results demonstrate the feasibility and reliability of jitter detection and compensation. The variation law analysis of jitter indicates that the frequencies of jitter of ZY-3 satellite hold in the range between 0.6 and 0.7 Hz, while the amplitudes of jitter of ZY-3 satellite drop from 1 pixel in the early stage to below 0.4 pixels and tend to remain stable in the following stage.