No description available.

A technique for measuring fluid velocities by means of neutrally-buoyant, phophorescent particles was investigated in a small-scale water jet facility. A nitrogen laser briefly illuminated the flow, exciting only those particles resident within the pulsed beam. The particles luminesce for a short while following excitation, during which time they also move with the flow. This creates a visible particle streak, the intensity of which decays along the direction of motion. A strobe illuminates the particles again a known time following the laser pulse. The magnitude and direction of a particle's velocity in the plane of view are deduced from an image of it streak captured by a video camera and recorded by a digital image processing system.

<p> The Baccalaureate Nursing program in San Antonio, Texas experienced a decrease in National Council Licensure Examination for Registered Nurses (NCLEX-RN) on the first attempt for students graduating between 2009 and 2014 without a clear explanation for the decline. The purpose of this quantitative non-experimental correlational study was to analyze retrospective data from the school of nursing in San Antonio to determine the extent to which multiple variables (age, gender, race/ethnicity, cumulative pre-nursing GPA, cumulative GPA of nursing courses, remediation, and the Assessment Technologies Institute (ATI) examination predicted NCLEX-RN performance. The research question was: Is the ATI comprehensive examination a significant predictor of the NCLEX-RN performance of graduating nursing students in the San Antonio, Texas nursing program, either (a) on its own; or (b) in combination with other independent variables. The statistical problem was directed toward identifying the significant variables that predicted the NCLEX-RN performance of graduating nursing students between 2009 and 2014 using binary logistic regression analysis. The proportion of N = 334, nurses who passed the NCLEX-RN was n = 232, 69.5%. The answer to the research question, based on odds ratios (OR) was that NCLEX-RN performance could not be predicted solely by using the ATI predictor examinations. The ATI examination score was the strongest predictor of passing the NCLEX-RN (OR = 1.59) Ethnicity (OR = 1.38) and the combined pre-nursing and nursing GPA (OR = 1.28) were also found to be predictors of NCLEX-RN performance. The proportions of NCLEX-RN failures and need for remediation were highest among the African-American students. The gender and age of the students were not significant predictors of NCLEX-RN performance. The results of this research can be utilized by the San Antonio nursing program, as well as other nursing programs, to identify and address the factors identity of those graduating nursing students who are at risk of failing the NCLEX-RN. The researcher has shown that the predictor variables of the ATI predictor examination, cumulative college and nursing GPA&rsquo;s, and ethnicity have a statistically significant correlation and therefore have impact on first time NCLEX-RN test takers passing the exam. It is recommended that Bachelor Degree Programs in Nursing focus on specific strategies within their institutions that would have a direct impact on these variables.</p>

Στην παρούσα διατριβή πραγματοποιήθηκε ανάλυση καταγραφών επιταχυνσιογράφων που προήλθαν από πειράματα σύμφωνα με τα οποία επιταχυνσιογράφοι ίδιου τύπου κατέγραφαν την ίδια δυναμική κίνηση. Σκοπό των πειραμάτων αποτελούσε η διερεύνηση της διαφοράς των τιμών της επιτάχυνσης που προέκυπταν από κάθε όργανο, του φαινομένου της διαφοράς φάσης και του συχνοτικού περιεχομένου των καταγραφών αυτών. Για τη διεξαγωγή των παραπάνω πειραμάτων σχεδιάστηκε, από το εργαστήριο γεωδαισίας και γεωδαιτικών εφαρμογών, πειραματική διάταξη η οποία έφερε σε συγκεκριμένες θέσεις τους επιταχυνσιογράφους. Στο σύνολο πραγματοποιήθηκαν πενήντα δύο διεγέρσεις εκ των οποίων αναλύθηκαν οι τέσσερις πιο αντιπροσωπευτικές. Αρχικά, για κάθε διέγερση, υπολογίστηκαν οι μέγιστες τιμές επιτάχυνσης στις τρεις κάθετες μεταξύ τους διευθύνσεις (Χ-Υ-Ζ) από δύο επιταχυνσιογράφους και συγκρίθηκαν μεταξύ τους. Στη συνέχεια, διερευνήθηκε η ύπαρξη του φαινομένου της διαφοράς φάσης και το συχνοτικό περιεχόμενο κάθε χρονοσειράς. Επίσης, πραγματοποιήθηκε προσομοίωση της πειραματικής διάταξης σε κατάλληλο πρόγραμμα και προσδιορίστηκαν με ιδιομορφική ανάλυση τα δυναμικά της χαρακτηριστικά με σκοπό τη σύγκριση αυτών με τα αποτελέσματα που προέκυψαν από την επεξεργασία των καταγραφών των πειραμάτων. Εν κατακλείδι, οι επιταχυνσιογράφοι είναι όργανα που προσεγγίζουν σημαντικά ίδιες κυματομορφές επιτάχυνσης παρέχοντας όμως υπολογίσιμες αποκλίσεις όσον αφορά τις μέγιστες καταγραφές. Το φαινόμενο της διαφοράς φάσης, στις περισσότερες περιπτώσεις, εμφανίστηκε κυρίως μεταξύ των πρώτων μέγιστων καταγραφών καθώς με την πάροδο του χρόνου εξαλείφονταν. Αντίστοιχα, οι πρώτες ιδιοσυχνότητες με τα μεγαλύτερα πλάτη ταλάντωσης που προέκυπταν από FFT ανάλυση των μετρήσεων των δύο υπό εξέταση επιταχυνσιογράφων παρουσίαζαν ίσες τιμές σε όλες τις διευθύνσεις αναδεικνύοντας με αυτό τον τρόπο μια επιπλέον χρήση των οργάνων αυτών όσον αφορά την ανίχνευση ορισμένων περιοδικών χαρακτηριστικών ενός σήματος. / -

published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering

No description available.

The recession portion of the ephemeral stream hydrograph is modeled as a conceptual analog of the discharge from a single leaky reservoir. Physically, the reservoir may be considered to approximate that portion of the ephemeral stream channel that is flowing at the beginning of recession. The discharging reservoir is described by a continuity equation and by discharge-stage and storage-stage relations. No input is routed through the reservoir. It is assumed that initially (at the beginning of recession) the reservoir has water in storage. The discharge-stage relation for the reservoir is defined by the rating curve for the stream and storage-stage depends on reservoir configuration. A good agreement between observed and model curves is obtained by optimizing two parameters, reservoir leakage rate and initial storage, The agreement is most sensitive to changes in initial storage. Best parameter values are physically realistic and best reservoir configuration has leakage that varies directly with stage (depth) and storage that varies as the square of stage.

Data compiled from standardized procedures for width measurement at established streamflow gaging stations were used to develop a power-function relation between width in feet (W(A)_), and mean discharge in acre-feet per year (Q), for high-gradient perennial streams. Highgradient channels, which generally exhibit low variability for most factors influencing the width-discharge relation, were selected to indicate a standard exponent in the power-function equation. Flume data supported extrapolation of the high-gradient relation, Q = a w(A)¹•⁹⁸, through five orders of discharge magnitude. Further support for a standard exponent of the regression equation was provided by data from Kansas streams that had very silty beds and similar gradients, climate, and vegetation. Regression analysis of data from these streams gave an exponent of 2.01. Hence, a constant exponent of 2.0 was used for the width-discharge relation of all streams. To account for the effect of sediment on channel geometry, silt-clay percentages of the bed and bank material of 98 perennial streams of the western and midwestern United States were introduced into the standard width-discharge relation. Bed and bank cohesiveness, as indicated by silt-clay content, is considered a measure of channel competence. Narrowest streams for a specific mean discharge occur where channel competence, due to fine material and other variables including channel armoring and lush riparian vegetation, is greatest. Thus, at constant discharge, stream width varies inversely with both bed and bank silt-clay content. Multiple-regression analysis yielded the equation: Q = 2.0 w(A)²•⁰ (SC(bd))⁰•²² (SC(bk))⁰•⁵⁷ where SC(bd) and SC(bk) are percent silt-clay of bed and bank material, respectively. The average standard error of estimate for the relation is 58 percent, much of which is inferred to result from excessive width caused by bank erosion of historically recent flood events. Other causes of deviation from the relation include errors associated with the collection and analysis of data, climate and riparian vegetation, discharge variability, and armoring by coarse sediment sizes. Studies showing that stream channels are widened during periods of flooding suggest that most streams subsequently narrow toward an equilibrium width at normal discharges. Assuming that about one-sixth of the data sets, those exceeding one standard deviation, indicate streams too narrow owing to unrepresentative data or recently deficient runoff, the multiple-regression equation was modified to define channel equilibrium. For known conditions of mean discharge and sediment characteristics, an equilibrium width, W(eq) , can be calculated. Comparison with the measured width, W(A), defines the instability ratio, W(A)/W(eq) , The instability ratio identifies the degree to which channel width varies from assumed equilibrium, and ranges from 1.0 to 1.5 for most perennial streams. The ratio of suspended load to bed load appears to be a principal determinant of channel morphology, whereas sediment yield affects the rapidity with which channel healing can occur after widening by flooding. Greatest channel instabilities generally occur in sandchannel streams of arid to semiarid areas. In humid areas, lush vegetation, which encourages accretion of fine sediment sizes to bank material, induces channel stability. Low discharge variability, as shown by springs and regulated streams, generally results in low values of instability. Utility of the multiple-regression equation includes estimation of discharge from ungaged basins, and prediction of short-term changes in channel morphology resulting from altered supplies of water or sediment. Isolation of the influence of sediment on the width-discharge relation also permits consideration of the effects of other variables on channel shape.

No description available.

The purpose of this study is to develop a method for predicting monthly flow duration curves for ungaged basins that are suitable for estimating average annual flow, and installed capacity and average annual energy generation at potential sites for hydropower development. The procedures were tested by developing monthly rainfall duration curves for five sample watersheds and then developing flow duration curves from the rainfall data. The methods were evaluated by comparing the predicted monthly flow duration curves to daily and monthly flow duration curves based on field data from the selected sites because a plant's potential energy output can be computed directly from a flow duration curve. The methods tested fit duration curves based on field data reasonably well and are suitable for preliminary evaluation of hydropower developments in ungaged basins.