End conditions for improved cubic spline derivative approximations

AbstractWe consider the problem of deriving accurate end conditions for cubic spline interpolation at equally spaced knots. In particular we derive a number of end conditions which lead to derivative approximations of high accuracy

A class of piecewise cubic interpolatory polynomials

A new class of C1 piecewise—cubic interpolatory polynomials is defined, by generalizing the definition of cubic X-splines given recently by Clenshaw and Negus (1978). It is shown that this new class contains a number of interpolatory functions which present practical advantages, when compared with the conventional cubic spline

THE EFFECT OF DELAY AND SEQUENCE ON BLASTING FRAGMENTATION RESULTS

Blasters use the delay between charges and the firing sequence of the explosive charges to help reduce vibrations and achieve the desired fragmentation. Although delay and sequence are recognized as very important for vibrations and fragmentation, only vibration models consider timing as a variable in the prediction tool, without any known model for fragmentation prediction based on the delay sequence. Of the few fragmentation models available, very few take delay into account and do not give guidance on row delay and/or sequence selections. With the invention of electronic detonators in 1984, there are new avenues to explore with sequence and timing. Currently, blasters shoot using a trial and error approach when deciding on what timing to use to optimize fragmentation to the operations’ needs. Experience and trial and error are usually the deciding factors on what delay is selected to get certain fragmentation. Delay sequence and its influences on fragmentation is the focus of this dissertation. Current fragmentation models look at what is the delay timing between holes. Rarely do they look at the delay timing of the whole shot. Current models also look at a general fragmentation for the shot based on some design parameters. With timing, it is important to look at fragmentation on a hole-by-hole basis. Dynamic confinement (a concept developed in this research) changes drastically with timing. Dynamic confinement is the level of void space in front of a hole that changes with time due to explosives energy and gravity. Changes in dynamic confinement produce important changes in the final fragmentation of the shot. Given the relation between dynamic confinement and timing, it is suggested that the fragmentation be looked on charge by charge and not just design or average for one hole, in contrast to current fragmentation models. In this research, a conceptual model was created using the proposed dynamic confinement theory to include row timing into fragmentation models. The dissertation looks at previous fragmentation models, the theory behind dynamic confinement, the Worsey-Silva model, and some full-scale testing for validation

Face recognition in an unconstrained environment for monitoring student attendance

Traditional paper based attendance monitoring systems are time consuming and suscep- tible to both error and data loss. Where technical advances have attempted to solve the problem, they tend to improve only small portions i.e. confidence that data has been collected satisfactorily can be very high but technology can also be difficult to use, time consuming and impossible especially if the overall system is down. Camera based face recognition has the potential to resolve most monitoring problems. It is passive, easy and inexpensive to utilise; and if supported by a human safeguard can be very reliable. This thesis evaluates a strategy to monitor lecture attendance using images captured by cheap web cams in an unconstrained environment. A traditional recognition pipeline is utilised in which faces are automatically detected and aligned to a standard coordinate system before extracting Scale Invariant Feature Transform (SIFT), Local Binary Pattern (LBP) and Eigenface based features for classification. A greedy algorithm is employed to match captured faces to reference images with faces labelled and added to the training set over time. Performance is evaluated on images captured from a small lecture series over ten weeks. It is evident that performance improves during the series as new reference material is included within the training data. This correlation demonstrates that the success of the system is determined not only by the on-going capturing process but also the quality and variability of the initial training data. Whilst the system is capable of reasonable success, the experiments show that it also yields an unacceptably high false positive rate and cannot be used in isolation. This is primarily because the greedy nature of the algorithm allows the possibility of assigning multiple images of the same person captured in the same lecture to different students including ‘no shows’

Method of Stemming a Blast Hole

A method of stemming a blast hole loaded with an explosive charge. The blast hole has side walls, an outwardly opening mouth and a central axis extending longitudinally of the blast hole. The method comprises inserting a conduit having a discharge end inwardly through the mouth of the blast hole and positioning the discharge end of the conduit within the blast hole generally adjacent the explosive charge. Particulate stemming material is forced under pressure through the conduit for exit from its discharge end into the blast hole toward the explosive charge thereby to pack stemming material in the blast hole adjacent the explosive charge. As stemming material is forced out the discharge end of the conduit, the discharge end of the conduit is moved generally axially outwardly relative to the blast hole toward the mouth of the blast hole to simultaneously fill and pack the blast hole with stemming material

An investigation of signs for median crossovers

“This paper describes a study of advance warning signs for median crossovers on divided highways. Candidate crossover signs were identified from a literature review, survey of current State practices and discussions with FHWA personnel. Seven of these signs were selected for further testing in a laboratory study for legibility, understanding and driver preference. Sixty subjects representing a cross-section of drivers took part in the study, thirty at the Turner-Fairbanks Highway Research Center in McLean, Virginia and thirty at the University of Missouri--Rolla in Rolla, Missouri. Two of the seven signs were word messages and five were symbolic signs. The results from both groups of subjects showed that the most appropriate word message sign would appear to be Median Crossover . This sign was understood the best by the subjects to whom it was shown and Crossover was the word the majority of subjects thought best conveyed the intended meaning. The symbolic sign found to be the best out of those tested was one showing two median noses. This did well In legibility and understanding tests and was least confused with other signs. It was also the symbolic sign most preferred by the subjects and was the simplest of the symbolic designs. Legibility of the symbolic signs was much greater than that of the word messages and this symbolic design is the sign recommended to identify median crossovers”--Abstract, page ii

An investigation of signs for median crossovers

“This paper describes a study of advance warning signs for median crossovers on divided highways. Candidate crossover signs were identified from a literature review, survey of current State practices and discussions with FHWA personnel. Seven of these signs were selected for further testing in a laboratory study for legibility, understanding and driver preference. Sixty subjects representing a cross-section of drivers took part in the study, thirty at the Turner-Fairbanks Highway Research Center in McLean, Virginia and thirty at the University of Missouri--Rolla in Rolla, Missouri. Two of the seven signs were word messages and five were symbolic signs. The results from both groups of subjects showed that the most appropriate word message sign would appear to be Median Crossover . This sign was understood the best by the subjects to whom it was shown and Crossover was the word the majority of subjects thought best conveyed the intended meaning. The symbolic sign found to be the best out of those tested was one showing two median noses. This did well In legibility and understanding tests and was least confused with other signs. It was also the symbolic sign most preferred by the subjects and was the simplest of the symbolic designs. Legibility of the symbolic signs was much greater than that of the word messages and this symbolic design is the sign recommended to identify median crossovers”--Abstract, page ii

The Causes of Armature Surface Fracturing Within Helical Flux-Compression Generators

Aluminum and copper tubes filled with explosive were tested during this study of high strain rate effects, as an adjunct to helical flux-compression generator research at the University of Missouri-Rolla, directly affecting the understanding of flux cutoff and high strain-rate changes in generator armatures. Longitudinal cracks characteristically developed in the outer surface of armatures at a smaller expansion ratio than predicted. These cracks occurred within two diameters of the detonator end of the armature but did not extend when the tubing expanded under explosive pressurization. Such cracks appear to cause magnetic flux cutoff, and flux losses seriously affect energy conversion efficiency. Energy, timing, and structural analyzes showed that detonation pressurization was not the cause of fracturing. A two-dimensional Lagrangian finite-difference numerical model was used to analyze the effect of detonation waves on the armature, and demonstrated that the cracking resulted from the stress field caused by the waves. Compressive detonation waves cause both compressive and tensile regions in armatures. This complex stress field causes low-cycle metal fatigue, affecting how the tube fractures when it is impulsively loaded by high-pressure detonation gases. Isolation of shock wave effects during operation is demonstrated in the paper, allowing for more efficient generators in practice