38 resultados para single-frequency fiber amplifier

em Deakin Research Online - Australia


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In this paper, a novel concept to determine the velocity and the location information of multiple mobile agents using Doppler radar has been introduced. Also, an expression for the minimum number of inline sensors needed to guarantee this estimation for n number of mobile agents has been obtained. Current methods use the time derivative of the displacement of adjacent position measurements to find the velocities of agents. This method is error prone, particularly, if the agents are accelerating. In our approach we incorporate direction-of-arrival (DOA) radar which tracks the location and the velocity of each and every agent in each measurement step.

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3-alkylpyrrole to the fabric surface. Direct applications of a conductive paint to the textile surface eliminate the exposure of the substrate to damaging oxidizing agents which allow the coating of more sensitive and delicate substrates. All textiles produced are tested for abrasion resistance and conductivity. For alkyl polypyrrole coated fabrics, the optimum carbon chain lengths are between n=10 and n=14, which result in optimum values of conductivity and solubility. The darkness of the tone is inversely related to the surface resistivity of the resulting conductive fabric. Therefore, deep black coatings have low resistivity whereas light gray coatings on a white fabric surface have higher surface resistivity. Longer alkyl chains result in higher surface resistivity in fabrics. The conductive coating of poly(3-decanylpyrrole) on the textile surface has a better abrasion resistance compared to that of an unsubstituted polypyrrole coating.

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This paper investigates the location and velocity estimation problem involving multiple targets using the phase difference and frequency shift of the returned Doppler modulated signal. The minimal receiver configuration that addresses the data association and missing information problem is presented for the case of linear arrays. Non-linearly modeled Doppler radar measurements are used to obtain an accurate estimate of the target dynamics progressively in a linear framework utilizing a recently developed robust state estimation approach.

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A recent model of the Single Fiber Analyzer 3001 (SIFAN3001) was firstly employed to obtain the single wool fiber diameter profiles (SfFDPs) at multiple orientations. The results showed that using SIFAN3001 to measure fiber diameter at four orientations for 50 single fibers randomly sub-sampled from each mid-side sample can produce average fiber diameter profiles (AS fFDPs) of fibers within staples. Within the testing regime used, the precision estimates for the total samples were ±1.3 µm for the mean fiber diameter of staples and 1.4 µm for the average fiber diameter of the AS fFDPs at each scanned step in the diameter profile. The mean diameter ratio (ellipticity) obtained from the four orientations was 1.08±0.01, confirming that the Merino wool fibers under review were elliptical rather than circular. The elliptical morphology of wool fibers and the precision of the fiber diameter measurement at each point along a fiber will be considered in the development of a mechanical model of Staple Strength testing.

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Fiber irregularity affects fiber mechanical properties. This study has, for the first time, introduced the concept of limiting irregularity to single wool fibers. The limiting irregularity is the minimum variation in fiber cross sectional area that can be expected of a single wool fiber, assuming a random length-wise distribution of its constituent cortical cells. Cortical cells were extracted from merino wool fibers and their dimensions were measured from SEM images to calculate their cross sectional area variations both between cortical cells and within cortical cells, and to work out the average number of cortical cells in the cross section of wool fibers of a given diameter. Single wool fibers were also measured at 5 µm interval along length for fiber diameter variations. These variations were found to be larger than that based on fiber limiting irregularity.

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Tracking mobile agents with a Doppler radar system mounted on a moving vehicle is considered in this paper. Dopplers modulated from mobile agents on the single frequency continuous wave signals are analyzed in order to estimate the positions and velocities of multiple mobile agents. The measurement noise is assumed to be Gaussian and the maximum likelihood estimation is utilized to enhance the localization accuracy.

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A generalized form of coupled photon transport equations that can handle correlated light beams with distinct frequencies is introduced. The derivation is based on the principle of energy conservation. For a single frequency, the current formulation reduces to a standard photon transport equation, and for fluorescence and phosphorescence, the diffusion models derived from the proposed photon transport model match for homogenous media. The generalized photon transport model is extended to handle wideband inputs in the frequency domain. © 2012 Optical Society of America.

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In knowledge discovery in single sequences, different results could be discovered from the same sequence when different frequency measures are adopted. It is natural to raise such questions as (1) do these frequency measures reflect actual frequencies accurately? (2) what impacts do frequency measures have on discovered knowledge? (3) are discovered results accurate and reliable? and (4) which measures are appropriate for reflecting frequencies accurately? In this paper, taking three major factors (anti-monotonicity, maximum-frequency and window-width restriction) into account, we identify inaccuracies inherent in seven existing frequency measures, and investigate their impacts on the soundness and completeness of two kinds of knowledge, frequent episodes and episode rules, discovered from single sequences. In order to obtain more accurate frequencies and knowledge, we provide three recommendations for defining appropriate frequency measures. Following the recommendations, we introduce a more appropriate frequency measure. Empirical evaluation reveals the inaccuracies and verifies our findings. 

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Although it is extremely important when interviewing children about alleged abuse to determine whether the abuse was a single or a repeated occurrence, we have little information about how children judge the frequency of events. The aim of the current study was to examine children's accuracy in providing estimates of event frequency that were numerical (that is, 1, 2, 3, . . .) and qualitative (that is, once, a few times, or many times). Younger (4- to 5-year-old) and older (6- to 8-year-old) children took part in a single event or an event that was repeated 6 or 11 times. They were interviewed after a short or long delay; some were interviewed a second time. Overall, children were very accurate at judging the frequency of a single event, but much less so for repeated events. Based on our findings, we make two recommendations for professionals trying to establish the frequency of events when interviewing young children.

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Subsequence frequency measurement is a basic and essential problem in knowledge discovery in single sequences. Frequency based knowledge discovery in single sequences tends to be unreliable since different resulting sets may be obtained from a same sequence when different frequency metrics are adopted. In this chapter, we investigate subsequence frequency measurement and its impact on the reliability of knowledge discovery in single sequences. We analyse seven previous frequency metrics, identify their inherent inaccuracies, and explore their impacts on two kinds of knowledge discovered from single sequences, frequent episodes and episode rules. We further give three suggestions for frequency metrics and introduce a new frequency metric in order to improve the reliability. Empirical evaluation reveals the inaccuracies and verifies our findings.

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In this paper, the effect of fiber dimensional irregularities on the tensile behavior of fiber bundles is modeled, using the finite element method (FEM). Fiber dimensional irregularities are simulated with sine waves of different magnitude. The specific stress-strain curves of fiber bundles and the constituent single fibers are obtained and compared. The results indicate that fiber diameter irregularity along fiber length has a significant effect on the tensile behavior of the fiber bundle. For a bundle of uniform fibers of different diameters, all constituent fibers will break simultaneously regardless of the fiber diameter. Similarly, if fibers within a bundle have the same pattern and level of diameter irregularity along fiber length, the fibers will break at the same time also regardless of the difference in average diameter of each fiber. In these cases, the specific stress and strain curve for the bundle overlaps with that of the constituent fibers. When the fiber bundle consists of single fibers with different levels of diameter irregularity, the specific stress-strain and load-elongation curves of the fiber bundle exhibit a stepped or “ladder” shape. The fiber with the highest irregularity breaks first, even when the thinnest section of the fiber is still coarser than the diameter of a very thin but uniform fiber in the bundle. This study suggests that fiber diameter irregularity along fiber length is a more important factor than the fiber diameter itself in determining the tensile behavior of a fiber bundle consisting of irregular fibers.

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Background Changes in the composition of gastrointestinal microbiota by dietary interventions using pro- and prebiotics provide opportunity for improving health and preventing disease. However, the capacity of lupin kernel fiber (LKFibre), a novel legume-derived food ingredient, to act as a prebiotic and modulate the colonic microbiota in humans needed investigation.

Aim of the study The present study aimed to determine the effect of LKFibre on human intestinal microbiota by quantitative fluorescent in situ hybridization (FISH) analysis.

Design A total of 18 free-living healthy males between the ages of 24 and 64 years consumed a control diet and a LKFibre diet (containing an additional 17–30 g/day fiber beyond that of the control—incorporated into daily food items) for 28 days with a 28-day washout period in a single-blind, randomized, crossover dietary intervention design.
Methods Fecal samples were collected for 3 days towards the end of each diet and microbial populations analyzed by FISH analysis using 16S rRNA gene-based oligonucleotide probes targeting total and predominant microbial populations.

Results Significantly higher levels of Bifidobacterium spp. (P = 0.001) and significantly lower levels of the clostridia group of C. ramosum, C. spiroforme and C. cocleatum (P = 0.039) were observed on the LKFibre diet compared with the control. No significant differences between the LKFibre and the control diet were observed for total bacteria, Lactobacillus spp., the Eubacterium spp., the C. histolyticum/C. lituseburense group and the Bacteroides–Prevotella group.
Conclusions Ingestion of LKFibre stimulated colonic bifidobacteria growth, which suggests that this dietary fiber may be considered as a prebiotic and may beneficially contribute to colon health.

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This paper describes a potentially faster and cheaper method of determining fibre scale frequencies. The method uses the single fibre analyser (SIFAN) to  determine the along the fibre diameter profile. This information is then analysed by the Fast Fourier Transform technique using computer software. The paper shows the close association between the mean scale frequencies determined by this method and the traditional approach using SEM.

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Objective Although the amount and frequency of child support payments received by single parents are often erratic and fluctuate, no study to date has quantitatively explored how the discrepancy between expected and actual payments relates to child health. This study aims to examine whether the discrepancy between expected and actual child support payments predicts a range of child health outcomes, including global health, health-related quality of life, involvement in activities and parental psychological distress.

Methods This study used results from the Longitudinal Study of Australian Children, which included a sample of parents of children aged 4–5 years (n = 4983). The questionnaire was completed by the parent who spent the most time with the child and knew the child best. From the 4983 families, 332 low-income single parents reliant on welfare with a formal or informal child support order in place were identified.

Results After controlling for income, the discrepancy between expected and actual child support predicted school functioning, conduct problems, total mental health problems and involvement in activities. Discrepancy between expected and actual child support payments did not predict the remaining health-related quality of life domains, mental health domains, global child health or parental psychosocial distress.

Conclusion This was the first study to examine how the discrepancy between expected and actual child support payments relates to child health, providing important data on the effectiveness of the child support system for children's well-being. These findings highlight the potential impact of the discrepancy on school functioning, conduct problems, total mental health problems and involvement in activities.

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To explore the relation between preeclampsia risk and maternal intake of dietary fiber, potassium, magnesium and calcium. STUDY DESIGN: We conducted a case-control study of 172 preeclamptics and 339 normotensive controls. Maternal dietary intake was assessed using a food frequency questionnaire. Logistic regression procedures were used to estimate the association between each dietary factor and preeclampsia risk. RESULTS: Fiber intake was inversely associated with the risk of preeclampsia. When extreme quartiles of total fiber intake were compared, the odds ratio (OR) for preeclampsia was 0.46 (95% confidence interval [CI] 0.23-0.92). The multivariate OR for preeclampsia for women in the top quartile of potassium intake (>4.1 g/d) versus the lowest quartile (<2.4 g/d) was 0.49 (95% CI 0.24-0.99). There was some evidence of a reduced risk of preeclampsia with a high intake of magnesium and calcium, though these results were not statistically significant. Intake of fruits and vegetables, low-fat dairy products, total cereal and dark bread were each associated with a reduced risk of preeclampsia. CONCLUSION: Our results support previous reports that suggest that diets high in fiber and potassium are associated with a reduced risk of hypertension. Maternal intake of recommended amounts of foods rich in fiber, potassium and other nutrients may reduce the risk of preeclampsia.