53,560 research outputs found
Rede uitgesproken op 17 september 1956 ter gelegenheid van de erepromotie van Dr. Th. von Karman door de promotor Dr. C.B. Biezeno
No full textRede uitgesproken door prof. C.B. Biezeno ter gelegenheid van de erepromotie aan de TH Delft van dr. Theodore von Karman.Precision and Microsystems EngineeringMechanical, Maritime and Materials Engineerin
Prof. Th. W. Adorno and the author Hans Erich Nossack.
No full textProf. Th. W. Adorno and the author Hans Erich Nossack at a reception of Insel Verlag, Buchmesse Frankfurt 1966LB
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
The Diamantina monazite: a new low-Th reference material for microanalysis
No full textMost monazite reference materials (RMs) for in situ U-Pb geochronology are rich in Th; however, many hydrothermal ore deposits contain monazite that is low in trace element contents, including Th, U and Pb. Because of potential problems with matrix effects and the lack of appropriate matrix-matched RMs, such variations can bias dating of hydrothermal deposits. In this paper, we describe a polycrystalline low-U and low-Th Diamantina monazite from the Espinhaço Range, SE Brazil. It has a U-Pb ID-TIMS weighted mean 207Pb*/235U ratio of 0.62913 ± 0.00079, 206Pb*/238U of 0.079861 ± 0.000088 and 207Pb*/206Pb* of 0.057130 ± 0.000031, yielding a weighted mean 206Pb*/238U date of 495.26 ± 0.54 Ma (95% c.l.). In situ dates acquired with different methods (LA-(Q, SF, MC)-ICP-MS and SIMS) are within uncertainty of the ID-TIMS data. U-Pb LA-(Q, MC)-ICP-MS runs, using Diamantina as a primary RM, reproduced the ages of other established RMs within < 1% deviation. The LA-MC-ICP-MS analyses yielded homogeneous Sm-Nd isotopic compositions (143Nd/144Nd = 0.511427 ± 23, 2s; 147Sm/144Nd = 0.1177 ± 13, 2s) and εNd(495 Ma) of −18.7 ± 0.5 (2s). SIMS oxygen isotope determinations showed measurement reproducibility better than ± 0.3‰ (2s), confirming Diamantina's relative homogeneity at test portion masses below 1 ng
Detection of partially coherent optical emission sources
No full textDetection of airborne optical emission sources in Infrared Search and Track (IRST) systems is usually carried out using the blackbody temperature or emissivity difference between the emission source and the background. Recent countermeasure techniques include emissivity tailoring and temperature distribution tailoring across the emission source area to avoid the formation of "hot spots" which effectively embeds the emission source in its background. A technique relying on coherence rather than irradiance is presented, allowing detection with poor signal-to-clutter ratios.The technique has some similarity with Fourier Transform Spectroscopy (FTS), and its key components are a Michelson interferometer, which measures the coherence profile of the scene in the field of view, and an interference filter, which uses the background illumination to create amplitude minima in the interferogram envelope. Unlike FTS, the interferometer moving mirror scans only a tiny portion of the interferogram, this being the region surrounding the first minimum of its envelope. It is shown that this envelope is a sine function, and that at this minimum the phase of the interferogram undergoes a pi phase step, which is used to define the position accurately, When a partially coherent emission source comes into the field of view, the modulus of the net complex degree of coherence of the scene increases, and the phase step position changes; this latter optical feature is used to declare detection.We present a simple theoretical model and compare it with experimental results for highly emissive sources having various coherence lengths in the presence of incoherent background illumination. Agreement between the experimental results and the theory is discussed
Mixed mode excitation and low cost control IC for electronic ballast
No full textThis paper introduces a gate-driven mixed mode excitation that is applicable to dimmable electronic ballasts. The proposed approach combines the characteristics of self-oscillating mode and external excitation. In the mixed mode excitation, the metal oxide semiconductor field effect transistors in an electronic ballast are turned on by the resonant current and turned off by the gate driver, which is triggered by a low voltage control integrated circuit (IC). By adjusting this triggering point, the low voltage control IC controls the switching frequency of the electronic ballast. In the electronic ballast with mixed mode excitation, filament preheating, dimming, and protection are all implemented by the low voltage control IC, which is fabricated in a 3.3-V standard CMOS process. The proposed approach allows for the realization of a low cost and high performance electronic ballast
COMPENSATION LOW-FREQUENCY ERRORS IN TH-1 SATELLITE
No full textThe topographic mapping products at 1:50,000 scale can be realized using satellite photogrammetry without ground control points (GCPs), which requires the high accuracy of exterior orientation elements. Usually, the attitudes of exterior orientation elements are obtained from the attitude determination system on the satellite. Based on the theoretical analysis and practice, the attitude determination system exists not only the high-frequency errors, but also the low-frequency errors related to the latitude of satellite orbit and the time. The low-frequency errors would affect the location accuracy without GCPs, especially to the horizontal accuracy. In SPOT5 satellite, the latitudinal model was proposed to correct attitudes using approximately 20 calibration sites data, and the location accuracy was improved. The low-frequency errors are also found in Tian Hui 1 (TH-1) satellite. Then, the method of compensation low-frequency errors is proposed in ground image processing of TH-1, which can detect and compensate the low-frequency errors automatically without using GCPs. This paper deal with the low-frequency errors in TH-1: First, the analysis about low-frequency errors of the attitude determination system is performed. Second, the compensation models are proposed in bundle adjustment. Finally, the verification is tested using data of TH-1. The testing results show: the low-frequency errors of attitude determination system can be compensated during bundle adjustment, which can improve the location accuracy without GCPs and has played an important role in the consistency of global location accuracy
Dissipative Range Scaling of Higher Order Structure Functions for Velocity and Passive Scalars
No full textDifferently to Kolmogorov's second similarity hypothesis, we find that the 2n-th order velocity and scalar structure functions scale with n-th order moment of the energy dissipation and the scalar dissipation, respectively. The origins of this scaling are analyzed by the transport equations of the fourth order velocity and scalar increment moments and by direct numerical simulations
Adolescents with Low Body Mass Index Are More Vulnerable to Pediatric Nondisplaced Femoral Neck Fractures
No full textBACKGROUND: Femoral neck fracture is a rare condition among fractures in the pediatric population. However, its potential for grave complications such as avascular necrosis or severe limb length discrepancy warrants prompt diagnosis and management. Much effort has been made to assess fracture risk in young adolescents in relation to obesity, low vitamin D levels, or young age osteoporosis. However, to our knowledge, there has been no literature that highlights a higher incidence of femoral neck fracture in adolescents with low body mass index (BMI). METHODS: At a level I trauma center, 22 early adolescents aged 10 years and older who had femoral neck fractures and underwent surgical treatment were included in the study. At the time of injury, BMI of each patient was stratified into 5 categories (underweight, normal weight, overweight, moderate obesity, and extreme obesity) based on BMI for age. Underweight was defined as a BMI below the 5th percentile, normal weight as between the 5th and 85th percentile, overweight as between the 85th and 95th percentile, and obese as above the 95th percentile. Then the patients were divided into 2 groups according to trauma degree: high-energy trauma and low-energy trauma. Low-energy fractures were defined as those caused by all types of trauma except for accidents involving motor vehicles, bicycles, or ski and all falls from greater than standing height. Independent samples t-tests and Pearson's chi-square tests were conducted between the 2 trauma groups. RESULTS: Excluding 2 patients lost to follow-up, 4 of 13 patients (30.77%) in the low-energy fracture group were underweight, whereas none in the high-energy fracture group were underweight. Including valgus impacted femoral neck fractures, 7 femoral neck fractures were nondisplaced, while 13 were complicated with displacement and required closed reduction. Avascular necrosis was observed in 4 cases and limb length discrepancy in 3 cases. The mean BMI percentile differed statistically significantly between the 2 trauma groups (p < 0.05). CONCLUSIONS: Low-energy femoral neck fractures in adolescents appeared to be associated with low BMI. Future studies are required to clarify the relationship between low BMI and fracture risk
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
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