Heavy Satellite Research Articles

Study the capabilities of RTK Multi GNSS under forest canopy in regions of Indonesia

For more than two decade, the position on the earth can be precisely determined “real-time” in the order of few centimeters by Real Time Kinematic (RTK) GNSS (Global Navigation Satellite Systems) Method. Nevertheless, few limitations are still recognized such as degradation of accuracy against limited satellite visibilities (e.g. heavy satellite obstructions from forest canopy). It usually takes time to resolve the ambiguities or even in many occasion resulted in failure. Fortunately since recent years to the future seems more satellite systems beside GPS and GLONASS are being launched such as BEIDOU, GALILEO, QZSS, etc. It means that more satellite will be existed above the sky. The term GNSS has changed into Multi GNSS. This Multi GNSS is theoretically adding the value to previous GNSS System like GPS; problems of limited satellite visibilities (e.g. under forest canopy) to the position accuracy perhaps will reduce. Within this paper we try to do study the capabilities of RTK Multi GNSS under forest canopy in Indonesia. We observed by RTK in the forest areas which have canopy of 40 to 90 percent. As conclusion we found improvement in positioning result of even area of very limited satellite visibilities.

Experimental test for receiving X-Band data LAPAN-A3 Satellite with 5.4m antenna diameter

LAPAN-A3 / LAPAN-IPB Satellite launched on June 22, 2016 (03:56 UTC) as an experimental micro-satellite for remote sensing and monitoring of maritime traffic. The Satellite was launched as a secondary payload on ISRO Cartosat-2C as its main payload, the launch carried out at SDSC (Satish Dhawan Space Centre) in India using PSLV-C34 rocket launcher. The Satellite was in orbit polar sun-synchronous with a height of 505 km above sea level. It has an inclination angle of 97 degrees and heavy satellite 115 kg, with this orbit, the satellite will pass through Ground station 4 times (2 times during the day and two times at night) with a duration of the track at the time of the pass about 10-15 minutes. The Satellite payload carried 4 bands Line Scan Cameras and Digital Imager (SpaceCam). For main mission is the earth observation for food vegetables And as additional mission is carrying AIS (Automatic Identification System) receiver to monitor maritime traffic in the region of the poles, then Star Sensor made by LAPAN for qualifying room, then for scientific contained magnetometer sensor for monitoring the Earth's Magnetic field. The purpose of this scientific paper is to test the reception of data payloads of the LAPAN-A3 satellite on X-Band frequency of 8.2 GHz using a 5.4 M solid antenna Ground Stations LAPAN in Pare-Pare. The purpose of this experiment will tell us with 5.4 meter of diameter solid antenna is capable or not enough for HDRM receiver to lock a signal and produce the data output, and how this result if compare with 11 meter of diameter antenna in Splitzberg Groundstation in Norway.

Internal resonances and their bifurcations of a rigid-flexible space antenna

The nonlinear dynamics of a flexible space antenna supported by a serial of two rigid arms mounted on a heavy satellite is studied under the conditions of 2:1 or 3:1 internal resonances. The nonlinear dynamic equations of the in-plane vibration of the antenna system of three degrees of freedom are derived first via the method of assumed modes. Then, the resonance and non-resonance regions are determined in terms of the dimensionless parameters of a rigid arm and a torsional spring in the antenna system. Afterwards, the approximate analytic solutions of frequency-amplitude response of the antenna system under 2:1 or 3:1 internal resonances are derived by using the method of multiple scales. Furthermore, the topologic description for the bifurcation of each internal resonance with respect to unfolding parameters is studied by means of the theory of singularity. Finally, the accuracy of the approximate analytic solutions is validated via the numerical solutions. The study shows that the internal resonances exist over a wide range of the detuning parameter. In addition, the 3:1 internal resonance exhibits much more complicated bifurcation topology than the 2:1 internal resonance. The approximate analytic solutions of internal resonances and their bifurcation analysis results provide an essential reference for designing the antenna system of concern.

Comparative Chromosome Map and Heterochromatin Features of the Gray Whale Karyotype (Cetacea)

Cetacean karyotypes possess exceptionally stable diploid numbers and highly conserved chromosomes. To date, only toothed whales (Odontoceti) have been analyzed by comparative chromosome painting. Here, we studied the karyotype of a representative of baleen whales, the gray whale (Eschrichtius robustus, Mysticeti), by Zoo-FISH with dromedary camel and human chromosome-specific probes. We confirmed a high degree of karyotype conservation and found an identical order of syntenic segments in both branches of cetaceans. Yet, whale chromosomes harbor variable heterochromatic regions constituting up to a third of the genome due to the presence of several types of repeats. To investigate the cause of this variability, several classes of repeated DNA sequences were mapped onto chromosomes of whale species from both Mysticeti and Odontoceti. We uncovered extensive intrapopulation variability in the size of heterochromatic blocks present in homologous chromosomes among 3 individuals of the gray whale by 2-step differential chromosome staining. We show that some of the heteromorphisms observed in the gray whale karyotype are due to distinct amplification of a complex of common cetacean repeat and heavy satellite repeat on homologous autosomes. Furthermore, we demonstrate localization of the telomeric repeat in the heterochromatin of both gray and pilot whale (Globicephala melas, Odontoceti). Heterochromatic blocks in the pilot whale represent a composite of telomeric and common repeats, while heavy satellite repeat is lacking in the toothed whale consistent with previous studies.

A dynamical study on the habitability of terrestrial exoplanets – I. Tidally evolved planet–satellite pairs

We investigate the obliquity and spin period of Earth-Moon like systems after 4.5 Gyr of tidal evolution with various satellite masses and initial planetary obliquity and discuss their relations to the habitability of the planet. We find three possible outcomes: either i) the system is still evolving, ii) the system is double synchronous or iii) the satellite has collided with the planet. The transition between case i) and ii) is abrupt and occurs at slightly larger satellite mass ($m_s \sim 0.02m_p$) than the lunar mass. We suggest that cases ii) and iii) are less habitable than case i). Using results from models of giant impacts and satellite accretion, we found that the systems that mimic our own with rotation period $12 < P_p < 48$ h and current planetary obliquity $\varepsilon_p < 40^\circ$ or $\varepsilon_p > 140^\circ$ only represent 14% of the possible outcomes. Elser et al. (2011) conclude that the probability of a terrestrial planet having a heavy satellite is 13%. Combining these results suggests that the probability of ending up with a system such as our own is of the order of 2%.

Load Varying Polytopic Based Robust Controller Design in LMI Framework for a 2DOF Stabilized Platform

This paper tackles the problem of payload uncertainties through polytopic system formulation and robust controller design for a 2DOF parallel manipulator. Typically, such platforms are used as a base for different payloads, e.g. satellite antenna and camera in oceangoing crafts. Traditionally, these kinds of manipulators are modeled through a time varying nonlinear model, thus providing the rationale for a nonlinear or adaptive controller. Uncertainties due to load variations present a significant challenge for robust control design. In this paper, the authors have proposed a novel and practical approach to solve the variant payload dilemma for the stabilized platform. The novelty lies in extracting different linear models with distinct load conditions using the system identification method and quantifying them into a convex hull to formulate a polytopic system. A regulator is then designed by mixed H 2/H ∞ synthesis with pole-placement constraints in a linear matrix inequality (LMI) framework to compensate output disturbances. The results are compared with a Riccati-based H ∞ loop shaping controller. It is shown through simulations and experiments that an LMI design is a better choice for achieving robustness as well as performance. The hallmark of this work is the successful testing of the control strategy on a stabilized platform with heavy asymmetric satellite antenna to reject the tides’ effect in a deep, turbulent sea.

Spacecraft Reliability-Based Design Optimization Under Uncertainty Including Discrete Variables

computationally expensive sampling techniques. The computational cost of optimization approaches becomes prohibitivewhenconsideringdiscretetechnology andredundancychoicesasvariables.Thisworkpresentsagenetic algorithm with Monte Carlo sampling for probabilistic reliability-based design optimization of satellite systems. In thisapproach,confidence-levelconstraintsensurethatsystemreliabilityrequirementsaremetwithhighprobability. Thegeneticalgorithm–MonteCarlosamplingapproachiscomparedtoadeterministic margin-basedapproachthat enforcesmarginsorsafetyfactorsonthereliabilityofindividualcomponents.Thecomparisonshowsthatthegenetic algorithm–Monte Carlo sampling approach produces satellite designs that have low launch mass (a surrogate for cost) while achieving reliability requirements at specified high confidence levels, while the genetic algorithm– deterministic margin-based approach produces heavy satellite designs with excessive redundancy. Based on this work, extensions of a genetic algorithm-based approach for discrete optimization under uncertainty that may require less computational effort appear possible.

Amplification of tropharium rDNA in the telotrophic ovariole of the bug,Dysdercus intermedins

Summary In the telotrophic ovariole of the bug, Dysdercus intermedius, the highly endoploid tropharium nuclei which are functioning throughout the gonocycles were analysed with respect to rDNA amplification. The likewise polyploid follicle cell nuclei which degenerate at the end of each cycle of egg formation and diploid larval brain nuclei were used for comparison. A heavy satellite is pronounced only in the tropharium DNA. The restriction patterns after hybridization with a labelled probe of cloned rDNA indicated considerable differences in the amount of ribosomal genes present in the three types of nuclei. These results evidence a high degree of rDNA amplification in the germ-line derived tropharium nuclei, but nothing like this in the diploid or polyploid somatic cells. This is the first record of an amplification of rDNA in a telotrophic insect ovary occurring probably during early trophocyte differentiation. The developmental significance of high amounts of ribosomal genes in the long persisting tro...

Characterization and localization of cryptic satellite DNAs in barley (Hordeum vulgare)

Three satellites on the heavy side of the main band and two satellites on the light side were isolated in a pure from by preparative ultracentrifugation of H. vulgare DNA in Ag(+)/Cs2SO4 density gradients. The satellites were characterised in terms of their buoyant densities in CsCl and their thermal dissocation temperature in both native and reassociated forms to Cot 4. In CsCl gradients, heavy satellites formed a single peak whereas light satellites resolved into more than one component. Thermal transitions of some satellites indicated the presence of more than one molecular species. The multicomponent nature of thermal denaturation profiles was evident on differential analysis. Radioactive RNAs complementary to the three heavy satellites of H. vulgare were localised by in situ hybridization onto its nuclei and chromosomes. One heavy satellite (H3) was found to be distributed on all chromosomes, although one pair showed less hybridization compared to the others. The other satellite (H1) appeared to be present in a much lower amount on the chromosomes.

Non-random distribution of the TY1 elements within nuclear DNA of Saccharomyces cerevisiae

Ty1 homologous sequences appear to be non-randomly distributed among different density classes of nuclear yeast DNA. Characteristic patterns of Ty1 containing EcoRI fragments can be generated from the various DNA fractions. The sequences are particularly enriched in the A + T rich part of the main nuclear DNA fraction, while the frequency in the rDNA containing heavy satellite DNA is low. The transposon however, seems to be present in this dense fraction, at least for some strains.

Genome of the whooping crane

The genome of an endangered avian species, the whooping crane (Grus americana) has been examined using the methods of karyotype analysis, cytofluorometry, and analytical ultracentrifugation. This species has a karyotype (2n = 82) common to the other crane species previously examined with five autosomal pairs and one sex chromosome pair as the macrochromosomes, and a large number of microchromosomes. Sex chromosomes are heteromorphic in females permitting sexing by means of chromosome analysis. The DNA buoyant density in neutral CsCl reveals the presence of two heavy satellite bands, and uncommon finding when compared to previous studies of avian DNA.

Characterization of Satellite - DNA of Daucus carota L.

During a 24 hs labelling period with 3 H-thymidine in carrot tissue cultures growing with a high rate of cell division activity, the DNA of a heavy satellite (1.703 g/ml) was preferentially labelled. The DNA of this heavy satellite was characterized as highly repeated DNA. Nevertheless, in main band DNA (1.693 g/ml) repeated DNA sequences also occur to a considerable extent.

Isolation and characterization of satellite DNA from mustard seedlings

The DNA from mustard (Sinapis alba L.) seedlings was examined by neutral CsCl and Ag+/Cs2SO4 density gradient centrifugation. Different satellite fractions were revealed by these two methods. The satellite fractions obtained from the Ag+/Cs2SO4 density gradient could not be generally correlated with satellite DNA fractions observed in CsCl. In CsCl density gradient centrifugation, a main band at density 1,695 g/cm3 and a heavy shoulder at density 1,703 g/cm3 are found. By preparative CsCl gradient centrifugation the heavy shoulder can be enriched but not completely separated from the main band DNA.—Gradient centrifugation by complexing the DNA with Ag+ rf. 0.25 to DNA phosphate reveals three distinct fractions which are further characterized: The heavy satelite DNA fraction revealed by Ag+/Cs2SO4 gradient centrifugation has the same density in a CsCl gradient and the same Tm value as the main band, but differs from main band DNA in the details of its melting profile and in its renaturation kinetics. The light Ag+/Cs2SO4 satellite DNA fraction had a higher melting temperature corresponding to a GC-rich base composition. Differences between these 3 fractions are observed in thermal denaturation and renaturation profiles, hybridization in situ with ribosomal RNA, and their response to restriction endonuclease digestion. The light satellite fraction from the Ag+/Cs2SO4 gradient, rich in ribosomal cistrons corresponds to the heavy shoulder DNA of neutral CsCl gradients which also is rich in ribosomal cistrons. The heavy satellite fraction from Ag+/Cs2SO4 gradient which contains highly repetitive short nucleotide sequences could not be revealed by the classical CsCl gradient centrifugation technique.

Isolation of heavy satellite deoxyribonucleic acid from sea-urchin spermatozoa

Two different methods were used to isolate high-molecular-weight heavy satellite DNA from the spermatozoa of the sea-urchin Lytechinus variegratus. Purification of satellite rDNA (ribosomal DNA) by selective denaturation of the spermatozoal DNA followed by a separation of the native and denatured DNA in an aqueous mixture of poly(ethylene glycol)/dextran is affected by the molecular weight of the spermatozoal DNA. Enrichment of satellite rDNA by selective precipitation of main-band DNA by poly-L-lysine is cumbersome but more suitable.

Satellite DNA in differentiating chick tissues.

Embryonic chick DNA from different tissues was examined for differences which might indicate specific DNA amplification in somatic cells. The problem was approached by determining the DNA compositional heterogeneity and searching for possible variation in different tissues of the 12-day chick. Neural retina, muscle, and whole decapitated (general) chick DNA were analyzed in CsCl and Cs2SO4 density gradients. While overloaded CsCl gradients showed a main band (rho = 1.701 g/cm3) and a heavy shoulder (rho = 1.716 g/cm3), overloaded Cs2SO4 gradients displayed a main band (rho = 1.426 g/cm3) and a discrete heavy satellite (rho = 1.447 g/cm3). This satellite, comprising approximately 1% of the whole cell DNA, appeared to be of nuclear origin and not related to mitochondrial DNA, which was found to have a density of 1.426 g/cm3 in Cs2SO4. No differences were found in the densities of the main band or the satellite DNA in the DNA samples isolated from the different tissues. However, the method of DNA isolation was found to be of crucial importance when comparing satellite DNA's among different tissues.

Satellite DNA (II) from sea urchin (Lytechinus variegatus) sperm.

When DNA isolated from freshly collected sperm of sea urchin (Lytechinus variegatus) is centrifuged to equilibrium in CsCl, 2 heavy satellite bands appear beside the main band DNA. Satellite DNA (II) appears in between the main band DNA (rho = 1.695 g/cm3) and the rDNA satellite (rho = 1.722 g/cm3). Satellite DNA (II) has a buoyant density 1.710 g/cm3, corresponding to 50% GC content. It is speculated that the satellite DNA (II), which appears to be of high mol. wt, might contain the sequences complementary to histone mRNA.

Interaction des ions argent avec l'adn nucleaire de Chlorella pyrenoidosa: en|Interaction of Ag + ions with Chorella pyrenoidosa nuclear DNA

When centrifuged in Ag +-C s 2SO 4 gradients, Chlorella pyrenoidosa (strain 211/8b and strain Emerson) nuclear DNA exhibits a satellite, the density of which is heavier than that of the main band. The presence and the buoyant density of this satellite strongly depend on pH and molar ratio : Ag +/DNA-P (rf) of the DNA solution. The binding of Ag + ions on the heavy satellite occurs from the lower rf. It is quite unaffected by previous chelating agent treatment of the DNA solutions or by purification on hydroxyapatite columns. After removing of bound Ag + ions, the densities of the heavy satellite DNA and main band DNA return to the native DNA density in CsCl gradient.

The heavy DNA satellite of yeast and its relationship to the ribosomal RNA genes

The heavy satellite DNA of Saccharomyces carlsbergensis has been resolved by preparative NaI density gradient centrifugation. The rRNA genes were found to have a different density than the heavy satellite DNA. The heavy satellite DNA was found to be organized in clusters of molecular weight 15 × 10 6, while the majority of the rRNA genes were found to be organized in clusters of 90 × 10 6 or more. These results show that the rRNA genes are not located in the heavy satellite DNA.

Study of a haploid yeast strain with an unusually high rDNA content: II. Fractionation of the DNA in preparative Ag +-Cs 2 SO 4 density gradients

Yeast DNA has been fractionated in preparative Ag +-Cs 2 SO 4 density gradients. After complexing with silver ions at a pH of about 7, the rDNA appears in a defined heavy satellite component in the gradient. For our particular strain, the satellite represents about 15% of the total nuclear DNA and has been identified as the γ-DNA. In alkaline CsCl density gradients, the satellite DNA forms two bands, of which the light component hybridizes with ribosomal RNA. Reassociation experiments indicate that about 80% of the γ-DNA consists of repeating units of about 6 × 10 6 daltons.

Decreased synthesis of hepatic satellite DNA in pyrrolizidine alkaloidosis of the sheep

the proportion of heavy satellite in the DNA isolated from the livers of sheep suffering from experimental pyrrolizidine alkaloidosis is significantly lower (3.5%) than that found in the DNA from lovers of normal sheep (12%). Dehydroheliotridine, the major unbound, relatively stable metabolite of lasiocarpine and heliotrine, the alkaloids used in the study, was found to inhibit selectively the semiconservative replication of the satellite DNA in cultures of ovine kidney cells. It is suggested that the inhibition of the synthesis of satellite DNA may be related to an attack by the metabolite on the pericentromeric region where the majority of the satellite sequences are located.