bluuebunny/crossref_metadata_2025_split huggingface dataset:
An environment for modelling and simulating communication systems: Application to a system based on a satellite backbone
Authors: Cohen Atika , Mrabet Radouane 
Published: July 2007

AbstractThe availability of good software tools is vital to simulation practitioners. The objective of the OSISIM project (open system integrated simulator) is to set up an environment which integrates facilities and tools to build a communication system, and to study its performance. The environment is called AMS : atelier for modelling and simulation. Using it, the network architect, i.e. the user of the atelier, can quickly construct, in a graphical environment, a concise system from models of several standard networks available in a specific library, and execute the system in an efficient manner. Starting with an outline of the components of the atelier, we describe the AMS prototype, and the internal structure of basic models to be included in it. Moreover, a concrete example of a communication system including a satellite backbone is provided to illustrate how AMS is used to simulate such a system.
Impact of transmission delay in audiovisual communications
Authors: Dimolitsas Spiros , Corcoran Franklin L. , Phipps John G. 
Published: July 2007

AbstractIn this paper, the design and results are presented of an experimental study which was conducted in order to assess subjectively the impact of transmission delay in audiovisual communications. This study was undertaken using two 64 kb/s videotelephones which were connected over links incorporating simulated one‐way circuit propagation delays of 0 ms, 250 ms and 500 ms. From the results obtained it was concluded that audiovisual communication is weakly affected by propagation delay. In general, performance degradation between terrestrial and single‐hop satellite connections was minimal and in most cases statistically insignificant. A subsidiary conclusion is that the presence of the visual cues appears to mitigate the impact of transmission delay in audiovisual communication.
Transmission techniques for dab by satellite
Authors: Carrere G. 
Published: July 2007

AbstractThis study is a comparison between the CDMA and COFDM transmission techniques for digital audio broadcasting. Since broadcasting is used to establish a mobile or fixed link, it is necessary to set up a transmission technique which allows the optimum use of fading and multipath channels, particularly in urban locations. This paper sums up a comparative case study between the two transmission techniques mentioned above. The interest of this paper is to point out the added value brought by these transmission techniques for requirements such as multiple path problems with digital broadcasting with mobiles, frequency mapping and synchronization, capacity of the system, jamming protection capability, BER specifications, signal processing complexity, power control, spectrum efficiency and error correction operations. Finally, this paper tries to bring the appropriate conclusion which leads the OFDM process in Europe.
Satellite DAB
Authors: Briskman Robert D. 
Published: July 2007

AbstractService requirements for digital audio broadcasting (DAB) from satellites are presented, and plans for implementing such systems in various countries are surveyed. Technical and economic constraints, including satellite transmitter power, frequencies of operation, transmission bandwidth, service interference and user receiver design are discussed particularly for DAB systems employing mobile receiving terminals where transmission outage from blockage and multipath fading must be addressed. Transmission performance improvement techniques such as spatial diversity, modulation, coding and interleaving are described. An illustration of a specific satellite DAB system design is presented to show the technical and economic feasibility of such new services.
The worldspace programme: The first dab satellite service for the world
Authors: Fournié Patrick , Courseille Olivier , Samara N. A. , Rothblatt M. A. , Harris G. C. 
Published: July 2007

AbstractThe WorldSpace satellite DAB system will provide by 1998‐1999 dozens of high quality radio channels accessible to a potential audience of 4 billion people world‐wide who currently receive with various kinds of difficulty and limitations terrestrial radio programming. The system will consist of geostationary satellites, low cost radio receivers called StarMan™, and the associated ground control networks. The system will use state‐of‐the‐art digital audio coding techniques and, on board the satellite, baseband processing technology. This paper presents the overall description, performance and industrial organiazation of the system.
Flight 2 version of in‐orbit test transponder (IOTT2) for on‐board regenerative satellites
Authors: Mott Richard C. , Fiore Livio Di 
Published: July 2007

AbstractThis paper presents the design and realization of regenerative satellite on‐board bypass test equipment. Furthermore, two particular examples of an in‐orbit test transponder (IOTT) are discussed in detail. The IOTT1, developed for the first 30/20 GHz ITALSAT satellite (F1), was launched in January of 1991. IOTT1 has been a useful tool during satellite assembly, integration and pre‐launch tests. IOTT1 was successfully used to fully characterize the multibeam ITALSAT satellite in orbit.In general, the IOTT functions to bypass the demodulator, the baseband switchboard and the modulator of the multibeam package of the ITALSAT spacecraft payload, providing the ability to fully characterize the satellite's transponders using well‐established IOT test techniques.This paper describes and compares the design, fabrication and test of both ITALSAT in‐orbit test RF bypass transponders (IOTT1 and IOTT2) mounted on board the ITALSAT multibeam spacecraft, (F1) and (F2), respectively. The IOTT1 contains the first MMIC circuitry ever launched into space on a communications satellite. The improved IOTT2, fabricated for the second 30/20 GHz ITALSAT satellite (F2), is schedule for launch in early 1996.These fully space‐qualified designs incorporate COMSAT Laboratories' designed and fabricated MMIC Ku‐band amplifiers, lightweight waveguide Ku‐band channel filters and electronic power conditioner (EPC) and combined IOTT telemetry/command (T&C) circuitry.
Use of transportable test stations for measuring satellite coverage dependent parameters during IOT campaigns
Authors: Barthmann P. , De Vincenti P. , Moens C. 
Published: July 2007

AbstractThe in‐orbit tests of the satellite coverage dependent parameters require the rotation of the satellite around its pitch and roll axes in order to ‘bring’ the various coverage locations onto one fixed IOT station. Alternatively, several transportable test stations can be located at different sites in the coverage area in order to measure the satellite performances on site. Although the second technique does not provide enough measurement points to reconstruct the complete coverage of shaped beam antennas, it presents several advantages for which it is still used by EUTELSAT for the IOTs of its satellites in conjunction with measurements based on the satellite attitude movements.In particular, the transportable test stations are used to test the stability of satellite EIRP and IPFD at the edges of the coverage areas, where the performances are more sensitive to the pointing errors induced by thermal deformation or satellite attitude changes.This paper presents the common experience gained by EUTELSAT and ESA in testing the coverage dependent parameters of the first and second generation of EUTELSAT satellites. In particular, the paper deals with the use of the transportable test stations during the EUTELSAT II F1 to F3 acceptance tests and with the test campaigns performed at several sites in the eastern European countries.In the first case, the transportable test stations were used in conjunction with satellite rotations around the pitch axis in order to measure the coverage dependent parameters along several cuts parallel to the equatorial plane at different roll angles. In the second case, the transportable test stations were used to periodically repeat the EIRP measurements of many satellite channels over several hours in order to test the EIRP stability of the EUTELSAT II satellites.For both cases, the paper presents a synthesis of the most significant IOT results together with a comparison between these results and the values of the coverage dependent parameters predicted on the basis of the on‐ground tests.
G/T predictions of communication satellites based on a new earth brightness model
Authors: Fenech H. T. , Kasstan B. , Lindley A. , De Maagt P. J. I. , Badessi S. 
Published: July 2007

AbstractThe G/T predictions of communications satellites in the past usually stipulated that an antenna noise temperature of 290 K be used in the calculations. This, when compared to in‐orbit derived data, has resulted in large discrepancies (up to 3 dB). These discrepancies result directly from the use of a pessimistic value of the antenna noise temperature. The actual antenna noise temperature is lower because a portion of the spacecraft receive antenna pattern falls in deep space and because the brightness temperatures of large parts of the Earth are lower than 290 K. This discrepancy has become more apparent as technology of low noise amplifiers advances, thus making the antenna temperature the predominant factor when budgeting the system noise temperature of the spacecraft.This paper focuses on a model to determine the antenna noise temperature and especially how this model was directly verified in orbit during the acceptance campaign of EUTELSAT II‐F6 (Hot Bird 1). The methodology used for the determination of the integrated antenna temperature is also fully discussed. Full results are also presented.
Recent advances in ‘in‐orbit testing’ of communications satellites
Authors: Kasstan B. , De Vincenti P. , Schulze H. J. , Tharaud Y. 
Published: July 2007

AbstractAfter a successful launch of a new communications satellite, it is essential to test the communications subsystem while the spacecraft is in orbit so as to compare with prelaunch data in order to ensure that no impairment has resulted from the stress of the launch and to verify that the spacecraft payload is compliant with the specifications sought.The thrust of in‐orbit test technology has stemmed from the fact that the spacecraft has to be operational very quickly while not sacrificing the number of tests that have to be performed and increasing their measurement accuracies.Thus, in order to respond favourably to the cited criteria, microwave measurement techniques with more powerful computers and software technology have been used to automate the measurements.The paper is geared to the history, design, implementation and operation of EUTELSAT's in‐orbit test (IOT) facilities, and mostly reflects technological advances in communications satellite payload testing. The paper will first detail the hardware/software novel concepts of the measurement environment. Then new measurements are summarized. New spacecraft antenna mapping procedures are detailed both in measurement and spacecraft attitude aspects.
Low earth orbit satellite communications experiments using the digital signal processing payload on the PoSAT‐1 microsatellite
Authors: Sun W. , Sweeting M. N. , Hodgart M. S. 
Published: July 2007

AbstractThere is a growing interest in using networks of small satellites in low Earth orbit (LEO) to provide a variety of communications services in conjunction with small ground terminals. The only ’little LEO’ microsatellite digital store‐and‐forward communications network (HealthNet) in commercial operation at the time of writing uses microsatellites, communications payloads, and protocols designed and built at the University of Surrey, U.K. In order to provide an in‐orbit research test‐bed for improving communications with microsatellites in LEO by optimizing modulation and demodulation techniques, an advanced DSP payload, the digital signal processing experiment (DSPE), was included on board the latest Surrey microsatellite (PoSAT‐1). In‐orbit experiments using the PoSAT‐1 DSPE first optimized the existing non‐coherent CPFSK communication systems and then investigated the use of coherent MSK to provide a potential 3dB advantage while remaining compatible with the spacecraft systems. A novel DSP implementation of the Hodgart‐Massey coherent MSK demodulator/decoder was developed by the authors and its behaviour compared with the classical de Buda demodulator undertypical LEO conditions through a sequence of rigorous computer simulations and laboratory bench tests. The simulations and bench tests quantified a practical 2dB improvement in BER performance when compared with non‐coherent CPFSK, while also exhibiting considerable tolerance to the frequency and amplitude variations which are encountered in an LEO environment. These characteristics were subsequently confirmed by in‐orbit demonstrations using the PoSAT‐1 DSPE. The microsatellite, payload, modems and experimental results are presented in this paper and discussed with a view towards implementing an adaptable DSP‐based communications system capable of optimizing data throughput with LEO microsatellites.
Directed interesterification in glycerides. Reaction in presence of added glycerol
Authors: Eckey E. W. , Formo M. W. 
Published: July 2007

SummaryDirected interesterification, in which ester‐ester interchange is carried out in triglyceride mixtures with simultaneous crystallization of solid glycerides, has been applied to glyceride mixtures containing free hydroxyl groups. Solid glycerides precipitated from cottonseed oil with added glycerol were principally saturated diglycerides or saturated monoglycerides.The prineipal varables controlling the kind and proportion of solid precipitated during reaction from glycerides of a given original composition are the proportion of free alcohol groups, the time‐temperature schedule for the reaction, and the method of seeding, if any, used to start the crystallization. The method makes it possible to segregate the high‐melting and low‐melting fatty acids of a fat practically completely into separate ester fractions.
Non‐ionic detergents from wax
Authors: Griesinger W. K. , Nevison J. A. , Gallagher G. A. 
Published: July 2007

ConclusionNon‐ionic synthetic detergents having detergent properties similar to those of alkyl phenol polyethylene glycol ethers and alkyl mercapto polyethylene glycol ethers can be prepared by reacting the optimum quantity of ethylene oxide with the composite crude fatty acids made by the air oxidation of low melting chemical grade paraffin wax.
Studies on the detoxication of castor seed pomace
Authors: Kodras Rudolph , Whitehair C. K. , MacVicar Robert 
Published: July 2007

SummarySolvent extracted castor seed pomace has been shown to have a high acute oral toxicity for the rat and chick. This acute toxicity has been destroyed by various physical and chemical treatments designed to denature the toxic protein constituent, ricin. Of these, autoclaving for 15 minutes at 125°C. produced essentially complete destruction of ricin with minimal changes in the physical character of the pomace. Biological tests of the feeding value of the detoxified pomace as a protein source indicated that the material was not of high biological value. Microbiological analysis of the total seed protein for the principal amino acids showed that the protein contained relatively large amounts of glutamic acid and was serisously deficient in tryptophan. The methionine content was also inadequate and the lysine was marginal.
Thin lipid membranes with aqueous interfaces: Apparatus designs and methods of study
Authors: Howard Robert E. , Burton Robert M. 
Published: July 2007

AbstractThin membranes can be formed in aqueous media from amphiphilic lipids, and will spontaneously approach a limiting thickness of bimolecular dimensions (bilayers). This paper describes apparatus and methods for studying such thin lipid membranes, and illustrates their use in determining some of the basic properties of the membranes, especially bilayers.Several methods of forming thin lipid membranes are described. The early stages in apparatus development are traced, and the theoretical variables and operational parameters relating to apparatus and system design are discussed.Designs for two basic types of apparatus are presented in detail: one is a cylindrical chamber especially constructed to permit optical investigation of the membrane; the second is a multiple chamber system designed for the study of several different membranes either simultaneously or in rapid succession. Interchangeable chamber units are held in a thermostat block, and assemblies of electrodes and provisions for perfusion or sampling of aqueous medium are placed in the chambers as required. Methods are described which enable simultaneous mechanical, electrical, optical, and chemical operations and studies to be performed on the same membrane with either type of apparatus.Membranes were formed from several purified amphiphilic lipids and from mixed‐lipid extracts from a variety of biological membranes. The types and mechanisms of drainage of thin lipid membranes with aqueous interfaces are analogous to those previously described for aqueous soap films in air. The limiting bilayer thickness is confirmed by electrical measurements. The resistivity of the bilayers is ca. 1012 to 1014 ohm‐cm, their capacity is ca. 0.4 μfd‐cm−2 and their dielectric breakdown voltage is ca. 3×105 V‐cm−1. Other physical properties of the bilayers are described. Permeability of the bilayers to various substances was determined by diffusion flux, osmotic flux, and electrochemical potential methods using the apparatus described. Substances studied included water, small monovalent ions, glucose, acetylcholine, salicylamide and synaptic vesicles.The chemical, physical, electrical, and permeability properties of the experimentally formed lipid bilayer membranes are similar to those of biological membranes. These similarities strongly support the Danielli‐Davson hypothesis, which proposes that a lipid bilayer is the basic structure of biological membranes. The apparatus, methods, and information presented in this paper provide tools for further investigation of lipid bilayer membrane properties and for further testing of hypotheses relating to membranes.
Properties of lipid bilayers at a water‐water interface
Authors: Haydon D. A. 
Published: July 2007

AbstractThis paper is essentially a review of the work on black hydrocarbon films in aqueous media which has been carried out by the author and his colleagues during the last few years.The theory of the formation and stability of the films is discussed in terms of the structure and physical properties of the constituent molecules. Particular consideration is given to the adsorption of the stabilizing molecule and the metastable equilibrium of the resultant thin film. The various systems which have been examined experimentally are described. The interrelation of the film capacitances, thicknesses, and compositions is discussed in the light of the theoretical expectations.The films are permeable to water although the measurement of their permeability is complicated by the difficulty of stirring the boundary layers of the aqueous solutions. There is a discussion of the progress in this problem and the interpretation of the permeability measurements in terms of the structure and composition of the films.Finally some conditions under which films become strongly conducting are described.
Component fatty acids and composition of some oils and fats
Authors: Sreenivasan B. 
Published: July 2007

AbstractNineteen different samples of oils and fats have been examined for their component acids and composition by gas‐liquid chromatography. Under programmed‐temperature operations, the temperatures at which different components start to elute bear a straight‐line relationship with their respective carbon numbers. Chromatograms, under programmed‐temperature conditions, of methyl esters from such oils as coconut, groundnut, mustard, etc., are used for identifying the components of an unknown oil by comparing its chromatogram taken under nearly identical conditions. For confirmatory identifications, such plots as logarithm of retention times versus carbon numbers for saturated acids (14:0 to 24:0), monoenoic acids (14:1 to 24:1), and dienoic acids (18:2 to 24:2), under isothermal conditions, have also been used. Some new fatty acids, noted for the first time in traditional oils, are 15:0 in cottonseed oil, 20:1 in sesame oil, 22:0 in soybean oil, and 24:2 in mustard oil. Odd‐carbon chain acids from 11∶0 to 23:0 have been observed in such vegetable oils as peanut germ, rice bran, andMesua ferrea. Fatty acid composition by GLC for new samples like peanut lecithin, peanut germ oil,Myristica attenuata, Myristica kanarica, Myristica magnifica, Mesua ferrea, Vateria indica, Schleichera trijuga, and shark‐liver stearine are presented. Industrial utilization of these new oils and fats is discussed.
An electrophoretic study of the detergency process
Authors: Rutkowski B. J. 
Published: July 2007

AbstractBy using a micro‐electrophoresis technique, the electrokinetic behavior of cotton and a clay soil was studied in various surfactant, tripolyphosphate, and carboxymethylcellulose solutions. Correlative soil‐deposition studies were also made.Data are presented which show that doublelayer forces of repulsion are not of major importance in preventing the deposition of a clay soil on fabric. However a correlation was demonstrated between soil deposition and adsorption processes which occur at soil‐solution and fabric‐solution interfaces.
Elimination of the halphen response of cottonseed oils in conjunction with deodorization
Authors: Eaves P. H. , Dupuy H. P. , Holzenthal L. L. , Rayner E. T. , Brown L. E. 
Published: July 2007

AbstractTwo simple but effective pilot‐plant processes were developed to produce Halphen‐negative cottonseed oil. Both involve treatment of the oil with cottonseed fatty acids in a conventional batch type of deodorizer in conjunction with deodorization. In one process, in which the acids were added to the oil, the cyclopropenoids were inactivated in as short a time as 5 min after the oil reached the maximum temperature of 450–455 F. In the other, in which the acids were generated in situ, the oil did not become Halphennegative until about an hour and 45 min after it reached maximum temperature. The excess acids produced by both methods were readily removed during conventional deodorization. In contrast, deodorization alone reduced the cyclopropenoid content of the oil to a low level (0.02%) but did not render it Halphen‐negative even after 3 hr at maximum temperature.These new processes are directly applicable for use by refineries that have the batch type of deodorizers. For refineries that operate continuous or semicontinuous deodorizers, it should be relatively simple to design preheating vessels or heat exchangers to inactivate partially or completely the cyclopropenoids before deodorization.
Occurrence of Conjugated Cyclopropanoid Acid in Purified Fish Oil
Authors: Horii Naoto , Arato Shingo , Narayan Bhaskar , Hosokawa Masashi , Sashima Tokutake , Miyashita Kazuo 
Published: July 2007

AbstractThe presence of conjugated trienoic acids were found in the purified fish oil from the Japanese sardine by an analysis of high performance liquid chromatography equipped with a photodiode‐array detector. Gas chromatography–mass spectrometry indicated that main conjugated trienoic acids were those of 16:3, 20:5, and 22:6. Conjugated trienoic acid of 16:3 was identified as a cyclopropanoid acid with conjugated triene by NMR analysis. All conjugated trienoic acids were formed by heat treatment during the deodorization of fish oil, but not found after de‐gumming, alkaline refining, and bleaching. Conjugated trienoic acids of 16:3, 20:5, and 22:6 originated from 16:4n‐1, 20:5n‐3 (EPA), and 22:6n‐3 (DHA) in the fish oil during the heat treatment for deodorization.