Dissertations / Theses on the topic 'Radio kit'

The thesis aims to develop a prototype for a Smart Case for Remote Radio Kits at the department of Demo & Event at Ericsson in Kista.The smart case consists of a mechanical structure (the case itself with ) and an electronic system that includes a temperature sensor, a LCD display showing the temperature, a GPS (global positioning system) module for positioning the case, a GSM (Global System for Mobile Communications) module and a microcontroller Arduino UNO. The Case is modelled in 3D with the help of CAD software and then printed with a 3D printer. A down-scaled prototype is built with the help of the 3D printer and the 2D drawing will be used when the full scaled model is produced. The Arduino UNO handles temperature sensor and GPS measurements, LCD display, and the transmission of measurement data using GSM module via text message (SMS) to a cell phone or to a server over the Internet. The projected ended up with all the drawings and models finished for the Case as well as the implementation of down-scaled prototypes. The electrical system was tested and finished individually. But the complete system cannot be assembled inside the Case due to the time limitation. This means that the project can be further extended, where a full scale model can be developed and the electrical control system can be assembled together and mounted inside the Case.

This thesis presents a study of potential calibrators observed by the Karoo Array Telescope (KAT-7). The KAT-7 is an engineering prototype for the coming sensitive array, the MeerKAT, one of the pathfinders for the Square Kilometre Array (SKA). This thesis plays a supporting role in the ongoing commissioning activities of the KAT-7, whose construction started in early 2008, and which has been undergoing engineering and science verifications since late 2010. This thesis has achieved the first steps towards identifying possible flux-density standards for short baseline interferometers such as the KAT-7. The systematic error for flux-density calibration at KAT-7 was estimated relative to 3C123, and it was found to be ~5% of the measured flux density. 18 (~47%) of the 38 sources were identified as good flux density calibrator candidates, for their Modulation Index (MI) and Variability Index (VI) values were less than 0.05 and all the sources in the field had less than 10% of the peak flux density of the calibrator candidate. One source (PKS J0837-1951), which showed low variability and hence appeared to be a good flux-density calibrator candidate (class A), was deemed to be not a good flux-density calibrator candidate because a strong confusing source was found within its primary beam. Eight sources had MI or VI values between 0.05 and 0.09 and may deserve further study as potential flux calibrator candidates. Five sources had MI or VI values greater than 0.09 suggesting significant variability while 17 sources had only one or two observations so their suitability as potential flux calibrator candidates could not be evaluated. In addition, we used another measure of variability, the de-biased modulation index, for our sources comparing the observed modulation indices against Monte Carlo simulations. The result showed that the values of Md are largely as expected and the uncertainties therefore not substantially underestimated.

The study of cosmic magnetism is vital in fully understanding the role that magnetic fields play in the evolution of cosmological objects such as galaxies. The exact role played by magnetism in galaxy evolution is still not fully understood. This work aims to use wide band radio polarimetry to probe the frequency dependent polarization properties in a small sample of unresolved known disc and AGN powered radio galaxies and also in a larger faint radio source sample from a deep blind survey. The second sample is composed of lesser known faint radio sources spanning ∼ 4 square degrees. We also aim to develop broad band radio polarimetry techniques that can be utilised in the future. We observed six radio galaxies at frequencies spanning 1200−1900 MHz – divided into three 256 MHz bands centred on 1350, 1600, and 1850 MHz. We also analysed deeper wide band and wide field observations from the commissioning phase of the South African SKA precursor, MeerKAT. The MeerKAT observations are of the DEEP field, a radio quiet region in the southern sky. These observations were made at frequencies 890 MHz to 1702 MHz. Following data calibrations, we made sensitive (down to ∼ 7 µJy/beam) high resolution (6”) total intensity image maps for DEEP field source finding and characterization, as well as lower resolution (14”) IQU image cubes. We analysed sources with total flux density greater than one milliJy. The technique of Faraday rotation measure synthesis (RM synthesis) was employed through a python based algorithm to probe the broad band structure of the polarisation spectra. RM synthesis has the power to resolve individual contributions to the overall observed spectropolarimetric features along a line of sight. We found agreement with literature with regard to total radio intensities and the expected polarisation levels of order 1%. Our polarisation detection rate in the wide field case was estimated to be 24 ± 9% per square degree. This translates to 30 ± 13 polarised sources per square degree, in agreement with projections from the literature. The results confirm two main categories of polarised radio sources. These are: (1) sources with simple polarisation profiles, theoretically resulting from a scenario where incident polarised emission is Faraday rotated by a foreground region of coherent magnetic field such as in the case of a radio bright galactic nucleus emitting synchrotron radiation that then traverses disk and halo regions filled with a uniform magnetic field; (2) sources with complex Faraday spectra, indicating depolarisation and/or repolarisation suggesting other complex behaviour originating from several combinations of Faraday rotating and synchrotron emitting regions along the line of sight. We found that the most complex polarisation profiles emanate from the most polarised radio sources. From the sample of known sources observed with KAT 7, we found that unresolved disk dominated galaxies tended to be less polarised than compact sources suggesting a morphological dependence of the polarisation spectrum where disk galaxies may tend to have more regions within them, such as pockets of turbulent magnetic fields in the material disk, that may cause depolarisation to a larger degree as compared to earlier type non-disk dominated galaxies. Steep spectrum sources of different types (radio lobes and most polarised compact sources) show the most complexity with multiple Faraday emission components, depolarisation, and repolarisation. The more sensitive MeerKAT data allowed us to probe the broad band polarimetric properties of faint never observed radio sources. Our study is an early step to future campaigns with MeerKAT to explore relations between polarimetry and source properties, probing the correlations of magnetism with galaxy evolution and the evolution of large-scale fields in galaxies, galaxy groups and clusters.

Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: South Africa and Australia are now the two remaining countries bidding for the Square Kilometre Array (SKA), the biggest and most sensitive project ever undertaken in radio astronomy. The South African SKA is demonstrating its technology capabilities through the Karoo Array Telescope (KAT or MeerKAT). The development of KAT is taking place in stages to optimise design and minimise risks at each stage. An array of seven 12 m antennas will be complete by the end of 2009, called KAT-7. The following phase will see the construction of MeerKAT, which will lead to eighty arrayed dishes. Lightning and RFI studies for KAT-7 are the focus of this dissertation. Due to the extent and complexity of the South African demonstrator project, these studies have largely been conducted on a single structure. Parameters for the dish antenna and pedestal design changed throughout their development. To be effective, the doctoral research had to track these changes appropriately. A Method of Moments frequency domain computational electromagnetic code, FEKO, is used throughout the study. The consequences of direct and indirect lightning strikes are examined for the KAT-7 structure. Important FEKO model verification is achieved through measurement of physical scale models in an anechoic chamber. The microwave simulation code, CST, gives direct comparison of FEKO results by using a finite volume time domain method of calculation. Using frequency domain analysis on these models, the lightning down conductor design over the dish antenna bearings is optimised with cost-effectiveness as one driving parameter. RFI coupling levels for different designs are compared to each other to identify areas requiring RFI mitigation. Analysis of resonances enables evaluation of the mitigation at frequencies sensitive to radio astronomy. A Sommerfeld integral ground plane is used together with the computational model to investigate the use of the concrete foundation steel reinforcing as part of the lightning earthing electrode system. Different interconnections of the steel reinforcing elements are critically evaluated. The KAT-7 design incorporated clear lightning protection and RFI mitigation policies derived from recommendations contained within this dissertation.
AFRIKAANSE OPSOMMING: Suid-Afrika en Australie is nou die oorblywende twee lande wat bie vir die Vierkante Kilometer Reeks (SKA), die grootste en mees sensitiewe projek nog ooit in radio astronomie onderneem. Die Suid Afrikaanse SKA demonstreer sy tegnologiese bekwaamheid met die Karoo Reeks Teleskoop (KAT of MeerKAT). Die ontwikkeling van KAT vind plaas in fases om die ontwerp te optimaliseer en risikos te minimaliseer met elke fase. ’n Reeks van sewe 12 m antennas, genaamd KAT-7, sal teen die einde van 2009 klaar wees. Die volgende fase behels die konstruksie van MeerKAT, wat sal lei tot ’n tagtig-skottel reeks. Die fokus van hierdie proefskrif hanteer weerlig en radiofrekwensie steurings (RFS) vir KAT-7. As gevolg van die omvang en kompleksiteit van die Suid-Afrikaanse demonstreerder projek, is die studies hoofsaaklik op een struktuur gedoen. Parameters vir die antenna-skottel en -voetstuk ontwerp het met hul ontwikkeling deurgaans verander. Om effektief te wees, moes die doktorale navorsing hierdie veranderinge toepaslik volg. ’n Metode-van-Momente frekwensiedomein rekenaar elektromagnetiese kode, FEKO, is deurgaans met die studie gebruik. Die gevolge van direkte en indirekte weerligslae vir die KAT-7 struktuur is ondersoek. Belangrike FEKO model bevestiging is bereik met metings van skaalmodelle in ’n anego¨ıse kamer. Die mikrogolf-simulasie kode, CST, gee ’n direkte vergelyking met die FEKO resultate deur ’n eindige-volume-tyd-domein metode van berekening te gebruik. Met behulp van frekwensiedomein analise van hierdie modelle, is die weerligafleierontwerp oor die antenna-skottel laers ge-optimaliseer, met koste-effektiwiteit as een van die drywingsparameters. RFS koppelingsvlakke vir onderskeie ontwerpe is teen mekaar opgeweeg om areas te identifiseer wat RFS tempering benodig. Analise van resonansies stel die evaluering van die tempering in staat teen frekwensies wat sensitief is vir radio astronomie. ’n Sommerfeld integrale grondvlak word saam met die rekenaarmodel gebruik om die insluiting van die beton se staalversterking as deel van die aardingselektrodestelsel te ondersoek. Verskillende bindmetodes van die onderlinge staalversterkingselemente word krities ge¨evalueer. Die KAT-7 ontwerp inkorporeer duidelike weerligbeveiligings- en RFS temperingstrategie ¨e, komende van aanbevelings in hierdie proefskrif omskryf

The use of gas chromatography isotope ratio mass spectrometry (GC-IRMS) for compound specific stable isotope analysis is an underutilized technique because of the complexity of the instrumentation and high analytical costs. However stable isotopic data, when coupled with concentration measurements, can provide additional information on a compounds production, transformation, loss, and cycling within the biosphere and atmosphere. A GC-IRMS system was developed to accurately and precisely measure δ13C values for numerous oxygenated volatile organic compounds (OVOCs) having natural and anthropogenic sources. The OVOCs include methanol, ethanol, acetone, methyl ethyl ketone, 2-pentanone, and 3-pentanone. Guided by the requirements for analysis of trace components in air, the GC-IRMS system was developed with the goals of increasing sensitivity, reducing dead-volume and peak band broadening, optimizing combustion and water removal, and decreasing the split ratio to the IRMS. The technique relied on a two-stage preconcentration system, a low-volume capillary reactor and water trap, and a balanced reference gas delivery system. Measurements were performed on samples collected from two distinct sources (i.e. biogenic and vehicle emissions) and ambient air collected from downtown Miami and Everglades National Park. However, the instrumentation and the method have the capability to analyze a variety of source and ambient samples. The measured isotopic signatures that were obtained from source and ambient samples provide a new isotopic constraint for atmospheric chemists and can serve as a new way to evaluate their models and budgets for many OVOCs. In almost all cases, OVOCs emitted from fuel combustion were enriched in 13C when compared to the natural emissions of plants. This was particularly true for ethanol gas emitted in vehicle exhaust, which was observed to have a uniquely enriched isotopic signature that was attributed to ethanol’s corn origin and use as an alternative fuel or fuel additive. Results from this effort show that ethanol’s unique isotopic signature can be incorporated into air chemistry models for fingerprinting and source apportionment purposes and can be used as a stable isotopic tracer for biofuel inputs to the atmosphere on local to regional scales.

A key feature of social Hymenoptera is the division of labor in reproduction between one or a few fertile individuals – the queen(s) – and many sterile nestmates that function as helpers – the workers. The reproductive altruism of workers has long been considered as one of the most important paradox of Evolution. Today, kin selection (Hamilton 1964a,b) is recognized as a prime selective force for the evolution reproductive altruism in Hymenoptera. Hamilton’s kin selection theory states that workers may benefit helping relatives reproduce as long as the relatives they aid share a higher than average proportion of their genes with the workers and effectively pass on copies of the workers' genes to the next generation. Relatedness between colony members is therefore pivotal in kin selection theory, because it directly influences the benefits from indirect fitness. In social Hymenoptera, within-colony relatedness is usually high, because of the haplodiploid sex determinism system. However, several factors of the breeding system are known to affect the colony genetic structure and, hence, the workers’ indirect inclusive fitness: the number of breeders, their genetic relationships and their relative contribution to the reproduction. On the other hand, dispersal strategies influence the population genetic structure, which in turn may result in different interaction patterns between members from neighboring colonies. Despite its central role in the evolution of cooperation and reproductive altruism in animals, kin selection also predicts conflicts between colony members. Because the individuals from a colony are not genetically identical, their reproductive interests may be different (Trivers 1974). These conflicts are diversified, both regarding their actors and their causes (Trivers & Hare 1976; Bourke & Franks 1995; Keller 1995; Chapuisat & Keller 1999b; Keller & Reeve 1999; Sundström & Boomsma 2001). The first part of this work deals with the population genetic structure, mating system and dispersal strategies of two Pheidole ants, the Mediterranean ant Pheidole pallidula and the Mojave Desert ant Pheidole tucsonica. Chapter 1 investigates the population genetic structure, the breeding system, the colony kin composition and the colony genetic structure of the Mediterranean ant P. pallidula. This study was performed by using highly polymorphic DNA microsatellite marker loci. The results show that a single, unrelated male inseminates each queen. Colonies are monogynous (i.e. headed by one reproductive queen) or polygynous (i.e. headed by 2 to 4 functional queens). Moreover, they are genetically differentiated and form a population exhibiting significant isolation-by-distance, suggesting that some colonies originate through budding. Chapter 2 reports cross-species amplifications of microsatellite markers developed for the ant P. pallidula on 13 ant species belonging to the sub-family Myrmicinae. Moreover, levels of genetic diversity within a colony, as well as relationship among colonies are studied for the black ant Pheidole tucsonica. Chapter 3 characterizes the level of inter-nest aggression, the spatial distribution and the genetic structure of a P. tucsonica population. The results show that inter-colony aggression varies from none to “all out” fights and that it is largely non-transitive. No effect of geographical distance or genetic structure on inter-nest aggression levels is detected. Moreover, genetic data reveal high rates of polygyny and/or polyandry. Overall, these results do not support the idea of a simple mechanism of nestmate recognition through queen or worker-produced pheromones or environmental cues. The second part of this work is devoted to the queen-queen conflict over reproduction, and the queen-workers conflict over sex allocation in P. pallidula. Chapter 4 is a detailed analysis on the partitioning of reproduction among queens in polygynous colonies of the species. Our results show a significant departure from equal contribution of queens to reproductive female, male and worker production. Reproductive skew is greater for male production than for queen and worker production. There is no relationship between the magnitude of the reproductive skew and (i) the number of reproductive queens per colony, (ii) their relatedness and (iii) the overall colony productivity, some of the factors predicted to influence the extent of reproductive skew. Finally, this study reveals a trade-off in the relative contribution of nestmate queens to reproductive female and worker production. The queens contributing more to reproductive female production contribute significantly less to worker production. To our knowledge, such a trade-off is shown for the first time in the Formicidae. Chapter 5 focuses on queen-workers conflict over sex allocation. Colonies of the Mediterranean ant P. pallidula show a strong split sex ratio, with 85% colonies producing more than 80% sexuals of one sex. Genetic analyses reveal that this species has an unusual breeding system, with colonies being headed by a single or a few unrelated queens. As expected in such a breeding system, our results show no variation in relatedness asymmetry between monogynous (single queen per colony) and polygynous colonies. Nevertheless, sex allocation is tightly associated with the breeding structure, with monogynous colonies producing a male-biased brood and polygynous colonies almost only females. In addition, sex allocation is closely correlated with colony total sexual productivity. Overall, our data show that when colonies become more productive (and presumably larger) they shift from monogyny to polygyny and from male production to female production, a pattern that has never been reported in social insects so far. A new explanation based on the concept of the “tragedy of the commons” is proposed to explain the strong sex ratio specialization observed in P. pallidula and in other species characterized by facultative polygyny. Chapter 6 investigates the relationship between the breeding system (monogynous vs. polygynous colonies) and the biosynthesis rate of juvenile hormone. Previous works in P. pallidula showed (i) that maternal effects induced by hormones and/or other compounds transferred to the eggs could influence the caste fate of female eggs and (ii) that sex specialization is tightly associated with the breeding structure (monogynous colonies produce a male-biased brood and polygynous colonies almost only females - Chapter 5). This study reveals a strong relationship between the biosynthetic rate of juvenile hormone (JH) production and the breeding system. Because in this species the breeding structure is closely associated with colony sex ratio, we propose that the rate of JH in queens could be a critical parameter in colony sex ratio determination. Queens of P. pallidula would exert partial control over sex ratio by laying different proportions of worker-destined eggs and queen-destined eggs according to the structure monogynous or polygynous of their colony. To conclude, some perspectives for future research on the different topics presented in this work are suggested.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Current forensic DNA analysis utilizes capillary electrophoresis (CE) to separate short tandem repeat (STR) fragments based on their length. Next generation sequencing (NGS) is the next evolution of forensic DNA profiling, and though dedicated forensics protocols are still fairly new, it is only a matter of time before NGS becomes the new standard for forensic DNA profiling. Stutter has been a problem ever since forensic STR testing was first implemented. The slipped strand mispairing model is the proposed mechanism for how stutter occurs, and it appears to be an intrinsic part of the polymerase chain reaction (PCR). Samples that were run via the ForenSeq™ DNA Signature Prep Kit were amplified using the DNA Primer Mix A (DPMA) and then sequenced on a MiSeq FGx™ Forensics Genomics System. Samples were also amplified using the GlobalFiler™ PCR Amplification kit and fragment separation was done via capillary electrophoresis. Stutter ratios were calculated by dividing the read count /relative fluorescence unit of the stutter allele by the read count / relative fluorescence unit of the parent allele. Stutter ratio comparisons were made between the ForenSeq™ and GlobalFiler™ kits as well as between the parents and the children in the family pedigree, though only samples tested using the ForenSeq™ kit were used. Comparison of overall stutter ratios revealed that the ForenSeq™ kit produced higher stutter across all STR loci, except for D13S317 and D2S441, when compared to the GlobalFiler™ kit. The different chemistries between the two kits, potential usage of different polymerases, and the fact that the ForenSeq™ kit requires two rounds of amplification can serve as likely explanations for this difference. There was also quite a bit of variability observed for the stutter ratios between loci in the samples run using the ForenSeq™ kit. Possible explanations for this could be that the cluster generation step could produce more clusters for some stutter products over others. Comparison of the stutter ratios for the pedigree obtained from the Coriell Institute revealed no differences between the parents and the respective alleles inherited by the children when tested with the ForenSeq™ kit. Some loci showed a difference between the parent and children, but that could simply be due to the sample size. The utilization of NGS for STR testing can result in two alleles of the same length but different sequences, called isoalleles. Analysis of isoalleles present at D21S11 in the children samples from the Coriell Institute pedigree showed that the isoalleles had different mean stutter ratios. The results open the possibility of potentially utilizing sequence-specific stutter filters in the ForenSeq™ Universal Analysis Software. The model of the longest uninterrupted stretch (LUS) has been around for some time, though recently the block length of missing motif (BLMM) has been proposed as a better predictor for stutter ratios. The results of stutter ratio analysis at D21S11 show that as the length of the BLMM increases, so too does the stutter ratio.

It is of great importance to be able to unambiguously interpret deoxyribonucleic acid (DNA) profiles, especially with Low Template (LT) DNA and mixture DNA that may contain major and minor contributors. Reducing stochastic effects, such as heterozygote peak imbalance, dropouts, and stutter artifacts have been studied by scientists in order to improve the evaluation of low quality DNA profile. There has been much research on a compatible solute, trehalose, in its effectiveness in enhancing the polymerase chain reaction (PCR), especially with GC-rich templates of DNA, and thermal stabilizing Thermus Aquaticus (Taq) DNA polymerases. Based on previous research, the effect of trehalose on peak heights, peak height ratios, and stutter ratios (n-1) from 15 short tandem repeats (STR) loci of the AmpFℓSTR® Identifiler® Plus PCR Amplification Kit was evaluated with 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA, through the addition of 0M (control), 0.2M, and 0.4M of trehalose for each quantity of DNA. Although there was an observation regarding changes in average peak heights at 1ng of DNA with the addition of 0.2M, and 0.4M of trehalose, no conclusions could be made with the average peak heights for 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA. The reason is that the propagation of pipetting error during the preparation of each batch could have contributed to the difference in the amount of DNA between each conditions which can be directly reflected in peak heights. Furthermore, unexpected discrepancy between the average peak heights for 0.1ng of DNA from the first and the second experiments rendered 0.1ng of DNA incompatible for comparison. With regards to average peak height ratios for 0.025ng, 0.05ng, 0.1ng, and 1ng of DNA, and average reverse stutter ratios for 0.1ng, and 1ng of DNA, there were no evidence to suggest that 0.2M or 0.4M of trehalose had any effects. Consistent trends for 0.1ng (Exp. 1 and 2) and 1ng of DNA from a statistical analysis through one-way ANOVA of individual loci, suggested that trehalose may have varying effects on certain loci. However, this observation must be approached with caution as it is uncertain whether unique trends across each data sets for certain loci were observed by chance due to small sample sizes or due to mechanisms of stutters and trehalose that are currently unknown. Future studies regarding the effect of trehalose on peak heights should be done with more precision through minimizing pipetting error, which can be accomplished by preparing one batch from which aliquots are taken. The result of the research does not show enough evidence to prove the usefulness of trehalose since the addition of trehalose does not yield consistently higher average peak heights and peak height ratios, and lower average reverse stutter ratios across 15 STR loci. Therefore, our results do not support that 0.2M and 0.4M of trehalose are useful within the parameter of forensic DNA analysis as they do not enhance the polymerase chain reaction (PCR) and improve stochastic effects for DNA profiles.

The aim of my diploma thesis is comparison and evaluation of reproduction of goats on an eco-farm and on a conventional farm. Measures of reproduction of observed herds were assessed in the years of 2009 and 2010 on an eco-farm Hana Langová and on a conventional farm Bára Schneedorferová. On an eco-farm, a herd of 20 does was observed. Crossbreeds of White shorthaired goat, Brown shorthair goat, Boer goat and Anglo-Nubian goat; all bred with a White shorthaired buck and a Boer buck. On a conventional farm, a herd of 24 White shorthaired does and two crossbred does of White and Brown shorthaired goat was observed in 2009. In 2010, only 18 does were observed. In both years the does were bred with two Brown shorthair bucks. The measured results were compared with milk efficiency results between the two years and also between the farms. In both years, higher fertility was discovered on an eco-farm. On a conventional farm, very low fertility was observed in 2009 (116 %). On the other hand, fertilization was higher than on an eco-farm in both years. Very big difference was also observed in the ratio of male kids, which was in both years higher on a conventional farm, where all the bred animals (apart from one) are hornless. Reproduction is to a high extent influenced by external environmental factors and to a very small extent by genetics. A whole range of possible effects was omitted from the observations, however, the main ones were noted. Of all the observed measures of reproduction, the only one which could be substantially influenced by the breeding method is fertility.