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The presence of abnormally high signal levels beyond the horizon may be exploited for communication purposes. On the other hand, these high signal levels pose the threat of spatial co-channel interference. A long-term detailed investigation into the wideband characteristics of a typical transhorizon link was instigated by the Radiocommunications Agency (UK) to permit the compilation of the hitherto unknown channel parameter statistics. This thesis describes that investigation conducted at a frequency of 11.64 GHz on a 160 km transhorizon sea path between Cap d' Antifer (France) and Fort Widley (England). A channel sounder with a bandwidth of 31.25 MHz which allows the implementation of an automated time-critical continuous data acquisition strategy, is described in detail. The parametric estimation of time-domain model parameters, from measured channel transfer functions, in the context of multi path propagation is discussed. The Singular Value Decomposition Prony and Bayesian techniques are described in detail, having been chosen in preference to Fourier analysis because of their higher resolution potential. The deri vation and implementation of a novel Bayesian algorithm which incorporates prior knowledge concerning the channel parameters is presented. Multipath channel simulation data using differing channel models and varying signal-to-noise ratios has been generated and this data, together with field data, has been used to carry out a systematic and critical comparison between the Bayesian and the SVD_P approaches. It is shown that the Bayesian algorithm gives more accurate estimates of channel parameters, namely amplitudes and delays, especially when the signal-to-noise ratio is less than 30 dB. An 8 month long measurement campaign has generated a 110 Gbyte database of channel transfer functions. The estimated channel impulse response and the associated signal levels are used to discuss the underlying propagation phenomena on the link. It is shown that ducting propagation conditions occurred for a larger than expected period totalling 16% of the measurement time. This has been attributed to the dominance of surface ducting conditions in the summer. Troposcattering was found to be more prevalent in the winter. The risk of the channel being a source of interference was found to be greatest at about 20:00 GMT due to the presence of advection ducts and a minimum at about 10:00 GMT. Delay spread, Doppler spread, coherence bandwidth and fade depths have also been estimated from the database. The results show that there is a very strong correlation between these parameters and the wideband signal level. The median values of 35 ns and 6 Hz for the delay and Doppler spreads respectively, reveal that the transmission medium can be considered to be slowly varying. Coherence bandwidths greater than 250 MHz have been observed for 1 % of the time with a signal level of -2.7 dBf. Such a high value implies that to achieve acceptable interference levels on spatially aligned links, large frequency separations may well be required. Comparison with earlier CW investigation results (COST210 and follow-up research) show that the statistics of signal levels acquired from CW measurements also apply to wideband signals. However, there is a significant discrepancy between CW and wideband fading statistics due to frequency selective fading.

Ultrafast spectroscopy is used to study essential characteristics of solid-state materials. We use ultrafast techniques to study semiconductors at THz frequencies, as well as demonstrate new single-shot measurement techniques. The future of electronics is in the THz regime. We study a crucial characteristic of semiconductors used in devices: the critical field at which the material becomes conductive. GaAs is a promising semiconductor for high-speed devices, and we use enhanced THz electric fields to measure the critical fields at 0.7, 0.9, 1.1, and 1.5 THz frequencies. Single-shot spectroscopy is a technique used to measure ultrafast time scale laser pulses. We show that a new, optical-fiber-based single-shot technique can map out the electric field of THz pulses. Also, we show two variants on this single-shot theme that can be used to measure ultrafast signals. We compare a classic pump-probe measurement to two types of single-shot measurements that use either a spectrometer or a 3 km fiber optic cable and oscilloscope, and we discuss important considerations to recovering the sample response.

Santrauka Temos aktualumas. Populiariausias Lietuvoje naudojamas būdas stipruminėms grunto savybėms nustatyti yra statinis zondavimas. Tuo tarpu dinaminis zondavimas naudojamas labai retai, dažniausiai tik ten kur neįmanoma atlikti.statinio zondavimo. Tokia situacija susidarė dėl to, kad Lietuvoje nėra metodikos pamatų skaičiavimams pagal qd (dinaminio zondavimo) reikšmes ir projektuotojai nelabai supranta dinaminio zondavimo privalumų. Esant tokiai padėčiai dauguma inžinerinių geologinių tyrimų įmonių qd reikšmes verčia į statinio zondavimo reikšmes qc, nors perėjimo koeficientų iš qd į qc nėra nurodyta jokiuose inžinerinių tyrinėjimų bei statybos reglamentuose ir žininuose. Dėl to inžinerinės geologijos specialistai dažniausiai naudoja savo pačių išvestus koeficientus. Taigi šiame darbe, atliktų tyrimų dėka, bus bandoma pritaikyti optimaliausius perėjimo koeficientus iš qd ir qc. Norint nustatyti šiuos koeficientus, buvo gilintasi į perėjimo iš dinaminio zondavimo rezultatų į statinio zondavim rezultatus problemas. Darbo tikslas – suteikti informaciją inžinieriams geologams apie dviejų inžinerinių geologinių lauko tyrimų metodų efektyvumą. Uždaviniai: - išbandyti statinį ir dinaminį zondavimą konkrečioje teritorijoje, - palyginti gautus rezultatus, - surasti perėjimo koeficientus iš qd į qc. Pirmoje darbo dalyje autorius aprašo tyrimo objekto inžinerinės geologinės sąlygas Antroje dalyje STATINIO IR DINAMINIO ZONDAVIMO REZULTATŲ GRUNTŲ ANALIZĖ Trečioje dalyje gautų... [toliau žr. visą tekstą] / SUMMARY Relevance of the topic. The most popular method of the determination of soil resistance is the static probing test. Meanwhile, the dynamic probing test is applied very rarely, mainly in places where the static probing test may not be used. Such situation has occurred because of the lack of methodology base for calculations according to qd (dynamic probing) values in Lithuania, while the designers do not perceive the advantages of dynamic probing. In the present situation, most of the engineering geology testing companies translate qd values into static probing values qc, though coefficients of conversion from qd to qc are not given in any engineering survey or construction regulations or references. Therefore, experts of engineering geology mostly use their own derived coefficients. Thus, through performed tests, the most optimal coefficients of conversion from qd to qc shall be applied in this paper. In order to determine these coefficients, problems of conversion from dynamic probing results to static probing results were analysed. The goal of the paper is to provide information for engineers geologists on the efficiency of two methods of engineering geologic field tests. Tasks: - Testing of static and dynamic probing in a specific territory; - Comparison of received results; - Finding of coefficients of conversion from qd to qc. The first part of the paper describes the engineering geologic conditions of the testing object. The second part analyses the results of... [to full text]

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Wafer probing is a testing process to inspect semiconductor wafers before packaging for defects by checking the electrical conductivity via physical contact between the wafers and the probe card. During the contact process, the shape of the probe needle and the mounting configuration onto the probe card have large influences on the stresses and contact force that the probe needles experience. In this paper, static performance of a vertical-type probe needle integrated with floating mount technology is analyzed with a nonlinear finite element analysis. The comparison between fixed mount and floating mount technologies is a part of the analyses. The geometry of a vertical probe needle is optimized to minimize the stress that occurs during the overdrive process, while maintaining adequate force for proper contact with the wafer. Effects of major overall dimensions of probe needle on the maximum stress and contact force is analyzed first, and then curvature of the probe needle body is optimized by employing a constrained minimization function, fmincon, in MATLAB. The maximum stress in the vertical probe pin at 125 ??m overdrive is effectively reduced from 1339 MPa to 972 MPa by applying floating mount technology over the fixed mount, and further reduced to 666 MPa by applying the optimization scheme. The final optimized design induced the contact force of 5.217 gf, which is in the range of the required contact force of 5 to 8 gf. Fatigue life increased from 19,219 cycles to 108,129 by applying floating mount over fixed mount, and further increased to 830,596 for the optimized design.

High-resolution techniques to characterize the three-dimensional structure of nucleic acids are critical for understanding the mechanisms of action of biologically important RNA and DNA molecules. Methods based on chemical probing have been particularly useful in gaining insight into the structures of nucleic acids in solution. The hydroxyl radical has been widely adopted as a chemical probe for DNA and RNA structure since its first application to protein-DNA footprinting. This dissertation describes efforts to improve upon the current model of how the hydroxyl radical cleaves the RNA backbone, through the use of specifically deuterated ribonucleoside triphosphates (NTPs). The synthesis and purification of deuterated NTPs are described in detail, as well as their application to the study of two RNAs: the sarcin-ricin loop (SRL) RNA - a biologically active region of ribosomal RNA - and a short RNA designed to lack secondary structure. Measurement of deuterium kinetic isotope effects (KIEs) on the cleavage of these RNAs suggests that it is possible to use this experiment to identify the GUA base triple structural motif that is commonly found in RNA. Abstraction of a 5' ribose hydrogen atom in RNA yields a fragment containing a 5'-aldehyde terminus with the sugar and base intact. Comparison of primer extension products of cleaved SRL RNA with or without deuterium substituted at the C5' ribose position of uracil residues demonstrated that the 5' aldehyde-terminated fragment can serve as a template for reverse transcription. Implications of the presence of a 5'-aldehyde terminus on hydroxyl radical cleavage analysis are discussed in the context of reverse transcriptase-mediated primer extension, a commonly used method. Structural features of naked DNA molecules with known protein binding sequences were explored using hydroxyl radical cleavage analyzed by capillary gel electrophoresis. An application was written in MATLAB to deconvolute and integrate cleavage intensities of hundreds of peaks in an electropherogram. In many cases, comparison of the cleavage profile to the minor groove width found in an X-ray co-crystal structure of the DNA-protein complex revealed a high degree of correlation.

The purpose of this case study was to examine the types of questions a music teacher uses in the classroom and when, and with what frequency, those question types occurred. The questions an experienced general music teacher asked fourth-grade students over the course of five thirty-minute class periods were classified as either procedural/behavioral (36.17%), content (61.97%), or off-topic (1.86%) questions. The content questions were further categorized as either convergent or divergent, as well as whether they were instances of probing, prompting, or redirection. The participant asked an average of approximately 75 questions per class period, and the majority of these (85.84%; n = 200) were convergent. Though previous research has demonstrated the importance of the use of a variety of question types, this knowledge may not have translated to the classroom.

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2016. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2017-04-27T20:07:52Z No. of bitstreams: 1 2016_LuizCarlosdeFigueiredo.pdf: 6500104 bytes, checksum: 3e4e8d6a24a6dc8b5f300aaef47e2c43 (MD5) / Approved for entry into archive by Patrícia Nunes da Silva(patricia@bce.unb.br) on 2017-04-30T14:42:16Z (GMT) No. of bitstreams: 1 2016_LuizCarlosdeFigueiredo.pdf: 6500104 bytes, checksum: 3e4e8d6a24a6dc8b5f300aaef47e2c43 (MD5) / Made available in DSpace on 2017-04-30T14:42:16Z (GMT). No. of bitstreams: 1 2016_LuizCarlosdeFigueiredo.pdf: 6500104 bytes, checksum: 3e4e8d6a24a6dc8b5f300aaef47e2c43 (MD5) / Esta tese de doutorado aborda a medição de energia com instrumentação dinâmica para o penetrômetro leve conhecido como Dynamic Probing Light ou DPL e cujos ensaios são guiados pela International Reference Test procedure for dynamic probing (DP). Report of the ISSMFE Technical Committee on Penetration Testing of Soils – TC 16 with Reference Test Procedures - ISSMFE (1989). A região central do planalto brasileiro, apresenta extensas áreas com solos de baixa resistência à penetração dinâmica do SPT que resulta no aumento da incerteza para a estimative de carga, baseada nesse penetrômetro dinâmico. A presença no cenário da investigação geotécnica do DPL não se constitui em novidade, mas ainda não se conhece os parâmetros oriundos da medição de energia para esse penetrômetro leve. A medição da energia transferida às hastes do DPL foi feita com o uso de células de carga e acelerômetros. As células de carga foram instaladas em dois pontos: no topo e próximo do cone do DPL. Baseado na Equação da onda, foi empregado o método que considera os registros de força e velocidade no mesmo domínio do tempo, denominado EFV. A eficiência da energia do DPL foi considerada em relação à penetração permanente do cone do DPL. A medida da eficiência de energia conduziu a uma formulação da força dinâmica por penetração permanente do DPL, associada ao comprimento da haste penetrada no solo. Por fim, é apresentado um exemplo prático de aplicação da medida de energia do DPL para a engenharia com a formulação de um método para o cálculo da capacidade carga para estaca. O método tem por base a força dinâmica absorvida pelo solo, considerando o comprimento máximo de haste do DPL em 10 metros de profundidade. / This PhD thesis deals with energy measurement with dynamic instrumentation for the light penetrometer known as Dynamic Probing Light or DPL and whose tests are guided by the International Reference Test Procedure for Dynamic Probing (DP). Report of the ISSMFE Technical Committee on Penetration Testing of Soils - TC 16 with Reference Test Procedures - ISSMFE (1989). The central region of the Brazilian plateau presents extensive areas with soils of low resistance to the dynamic penetration of the SPT that results in the increase of the uncertainty for the estimative of load, based on these dynamic penetrometer. The presence in the DPL geotechnical research scenario is not new, but the parameters of energy measurement for this light penetrometer are not yet known. The energy transferred to the DPL rods was measured using load cells and accelerometers. The load cells were installed at two points: at the top and near the DPL cone. Based on the wave equation, the method that considers force and velocity records in the same time domain, called EFV, was used. The energy efficiency of the DPL was considered in relation to the permanent penetration of the DPL cone. The measurement of the energy efficiency led to a formulation of the dynamic force by permanent penetration of the DPL, associated to the length of the rod penetrated in the soil. Finally, a practical example of application of the DPL energy measure for engineering is presented with the formulation of a method for the calculation of the load capacity for cuttings. The method is based on the dynamic force absorbed by the soil, considering the maximum stem length of the DPL in 10 meters of depth.

Introduction: Dental implant abutments can be exposed to a variety of oral prophylaxis procedures. Instrumentation of restored dental implants could subject the apical collar of the implant restorative abutment to surface scratching. Scratched surfaces may pose a threat to the integrity of the soft-tissue seal around the apical portion of the abutment which eventually may compromise the alveolar support of the implant. The aim of this study was to objectively measure surface roughness on the apical collar of metal implant abutments induced by probing and scaling instruments. Materials and Methods: 14 standard transmucosal 3 in 1, 4.5 mm diameter abutments made of titanium alloy (BioHorizons, Atlanta, GA) and 4 instruments, UNC-15 metal probe, Periowise plastic probe, McCall SM 17/18 metal scaler and universal plastic scaler were used to conduct the study. 4 abutments were used for non-treated measures and 10 abutments were used for instrumentation measures. All abutments were divided into four sections. Abutments used for instrumentation were treated with one of the four indicated instruments, one instrument per each section. Surface roughness of untreated and treated surfaces was assessed using a contact profilometer. Analysis of variance (ANOVA) was used to compare surface roughness between untreated and treated surfaces. Results: ANOVA showed significant differences in surface roughness between the treated and untreated surfaces (p< 0.0001). Add hoc analysis using Tukey-Kramer HSD test showed no statistical differences between untreated measures and metal probe measures (p>0.05). On the other hand, statistical differences were noted between untreated measures with plastic probe measures (p= 0.05), plastic scaler measures (p=0.05) and metal scaler measures (p=0.05). The metal scaler measures were higher than plastic probe measures (p=0.05), and plastic scaler measures (p=0.05). Conclusions: Probing around implant abutments with a metal probe seems to have no relevant effect on abutment surfaces. In contrast, instrumentation with scalers (both metal and plastic) and plastic probe may cause adverse surface changes. It is not known if these changes have clinical relevance. / Oral Biology