909 results for 1990, Doctoral

  • Wavefront estimation in astronomical imaging.

    Irwan, Roy (1999)

    Doctoral thesis
    University of Canterbury Library

    The challenge in building astronomical telescopes is to obtain the clearest possible image of a distant star, which should appear as a single point. Extended objects, such as galaxies and planets can be regarded as collections of points. However, turbulence in the atmosphere degrades any optical signal that passes through it. The optical effects of the atmospheric turbulence arise from random inhomogeneities in the temperature distribution of the atmosphere. As a consequence of these temperature inhomogeneities, the index of refraction distribution of the atmosphere is random. Plane waves striking the atmosphere from space objects acquire an aberration as they propagate through the atmosphere. The plane wave's surface of constant phase is no longer planar when intercepted by a,n a.stronornica.l telescope. The prnctica.l consequence of a.tmospheric turbulence is that resolution is generally limited by turbulence rather than by optical design and quality of a telescope. There are a number of approaches to solving this problem, ranging from an orbiting telescope (the Hubble Space Telescope), adaptive optics, and post detection processing. The latter approaches have applications to less expensive ground based telescopes and have been the subject of many years of research. Adaptive optics is a general term for optical components whose characteristics can be modified in real time so as to alter the phase of an incident optical wavefront. An adaptive optics system can be used to correct for atmospheric induced distortions. Before any corrections can be applied, however, some measurement must be made of the phase distortions. It is the aim of this study to estimate the degradation of the wavefronts phase. Two approaches to do so are presented. Firstly, through wavefront sensors, which many adaptive optics systems have been devised from. Among them the Shack-Hartmann sensor is the most commonly used. The sensor requires a subdivision of the receiving pupil by means of sub-apertures, wherein the lowestorder deformation of the wavefront phase is estimated. This linearizes the problem of phase retrieval to solving a linear system of equations. A new analysis is presented which differs from previously published work in the estimation of the noise inherent in the centroid calculation used in this sensor. This analysis is supported by computer simulations. Secondly, the nonlinear approach of phase retrieval is discussed. The problem becomes how to relate the phase and magnitude of the Fourier transform. It is thus necessary to estimate the phase distortion in the instrument solely from measurements made at the image plane of the telescope. The process of phase retrieval is then divided into two distinct steps. The expression for the covariance of the phase distortion using a Kolmogorov model for the turbulence is derived first. This covariance is then employed as part of a formal Bayesian estimate of the phase distortion. It is also shown that phase retrieval can be employed as a robust technique for estimating the wavefront distortion using a lenslet array. The results obtained compare favorably with the alternative approach of phase diversity. Furthermore, the introduction of prior information, in the form of statistical information of the distortion, is shown to considerably enhance the success of the phase retrieval especially for very low light levels. A comparative evaluation shows the superiority of phase retrieval to Shack-Hartmann sensing, only if the local maxima are overcome. The principal drawback of phase retrieval is the relatively long computing time required to find the solution when general-purposed computer is used.

    View record details
  • Ring laser dynamics.

    King, Benjamin Thomas (1999)

    Doctoral thesis
    University of Canterbury Library

    The departure of the behaviour of large ring laser gyros from the ideal is examined. A detailed description of the experimental operation of large ring lasers is provided along with several new innovations in equipment layout, data collection and especially in data reduction. The limits on gyro performance due to noise are investigated. A review of literature regarding the fundamental limit placed on gyro resolution is provided. This limit is due to spontaneous emission in the gain medium of the laser and it is demonstrated that our ring lasers approach this quantum limit. Two entirely independent methods for evaluating the quantum noise induced linewidth are demonstrated to agree well. One of the methods, which uses a second order autoregressive model, is able to make accurate linewidth estimates in sub-second gate times. A complex model is proposed which accounts for specific observed light scattering phenomena within a ring laser. This model is compared with dual beam data taken from C-I and is able to describe frequency shifts and waveform distortion accurately. The model also performs favourably when describing locking profiles for low rotation rates and externally induced perimeter modulation. When locked to an external signal the ring laser is found to be an extremely sensitive low frequency vibration detector. The commissioning of a very large (14 m perimeter) prototype ring laser gyro, GO, is described along with a comparison with the smaller ( 4 m perimeter) gyros C-I and C-II. This prototype has proven to be an invaluable testing ground for designs and techniques to be used on a proposed high precision 16 m perimeter gyro named the Grossring (G).

    View record details
  • Modelling studies of coiled-coil protein in wool fibre

    Gan, Kaiwan (1995)

    Doctoral thesis
    University of Canterbury Library

    A multiple regression analysis has established a non-linear relationship between the backbone dihedral angles and theca coordinates obtained from the X-ray crystal structures of fourteen proteins. The regression equations have been applied to predict specific dihedral angles of each residue in the backbone of twenty-four proteins. Overall this method (NLRDT) predicts values of ɸ and ψ within a ± 45° window of those found in the X-ray structure with an accuracy of 94% and 91% and within a ± 30° window of 88% and 81%. Two methods for the assignment of motif from Cα coordinates are reported. For the first method motif is assigned from the dihedral angles predicted using the regression equations. If the predicted dihedral angles of a residue fall in the range of -15° > -90° and -10° >ψ> -70°, the residue is assigned as in an α-helix; and in the range of -90° > -150° and 95° < 170° as in a β-sheet. By the second method motif of the ith residue is assigned from the distance Ci-1α to Ci+2α (v6) and torsional angle Ci-1α, Ciα, Ci+1α, Ci+2α (v13). If these values for a residue fall in the range v6 v13 > 0° the residue is assigned as in an α-helix. If the values are in a range V6 > 8.7 Å and ǀv13ǀ > 100° the residue is assigned as in a P-sheet. For the twenty four proteins 23.7% of the residues by the former method and 19.6% by the latter method are assigned differently from the PDB. A Monte Carlo Protein Building (MCPB) method to construct the backbone and Cβ atomic coordinates of twenty-four proteins from known Cα coordinates is reported. The method selects values of dihedral angles from either ± 30° windows of the dihedral angle calculated for that amino acid by the Non Linear Regression Distance Torsion (NLRDT) method or from ranges established from a statistical analysis of the relationship between dihedral angles of the backbone and Cα coordinates for a protein data base. The averaged coordinates from ten backbone models of a protein were used to define a mean structure that was refined by energy minimisation using the AMBER force field (GB/SA). By the latter method the average atomic deviation and r.m.s.d. of the backbone and Cβ atoms is between 0.14 Å and 0.32 Å (average 0.22 Å) and 0.22 Å and 0.61 Å (average 0.43 Å) respectively. A comparison with other methods is made. A model of nine proteins including side chain atoms have been built from the known Cα coordinates and amino acid sequences using a Monte Carlo Protein Building Annealing (MCPBA) method. The Cartesian coordinates for the side chain atoms were established with bond lengths and angles selected randomly from within ranges of values previously determined by analysis of fourteen protein crystal structures and with torsional angles randomly selected from -180° to 180°. A simulated annealing technique is used to generate some 300 structures with differing side chain conformations. The atomic coordinates of the backbone atoms are fixed during the simulated annealing process. The coordinates of the side-chain atoms of the 300 low energy conformations are averaged to obtain a mean structure which is minimisation with the Cα atoms constrained to their position in the X-ray structure using the OPLS/AMBER force field with the GB/SA water model. The r.m.s.d of the main-chain atoms (without Cβ) compared with the corresponding crystal structures is in the range 0.20 Å to 0.64 Å with a average value of 0.45 Å. The r.m.s.d of the side-chain atoms is from 1.72 Å to 2.71 Å with an average of 2.26 Å. The r.m.s.d of all atoms is from 1.19 Å to 1.99 Å with an average of 1.61 Å. The method is insensitive to random errors in the Cα positions and the computational requirement is modest. A full atomic model of 7c and 8c-1 coiled coil rod domain in wool protein has been established from the amino acid sequences using the MCPB/MCPBA method. For the particular knob-hole heptad repeat, for the single α-helix the rise per residue is 1.464 Å; the twist angle per residue 102.999°; the number of residues per turn is 3.524 and the pitch 5.171 Å. For the four coiled coil helical segments of the rod domain the pitch is in the range 124 Å to 192 Å (average 172 Å); the radius of the coiled coil varies between 5.24 Å to 5.92 Å; the average value of the radius is 5.56 Å; the average crossing angle of the helices in the coiled coil is 23.0°; the number of residues per major turn is 127.3 and there are 36.2 minor turns in a major turn. The interaction energy between the two α-helical chains in the coiled coil structure is evaluated from van der Waals non-bonded interactions, electrostatic and hydrogen bonding interactions. The optimum relationship of the α-helical chains to each other established the heptad repeat interaction; 34% of the leucine residues are located at the d position. Of the backbone hydrogen bonds in the protein a-helix between residues four apart, 18% have a distance between a donor NH nitrogen and acceptor carbonyl oxygen greater than 3.5 Å .The hydrogen bonds between the side chains of the two a-helices in the coiled coil structure are largely between Arg and Glu, Arg and Asp and Glu and Asp. The distances of the Cβ atoms of cysteine residues are > 4.5 Å. This distance is outside that required for formation of disulphide bonds. The interaction of charged residues with apolar, polar and charged residues in the a-a, a-d, d-d, and d-a heptad positions accounts for 70% of the interaction energy.

    View record details
  • The chemistry of complex ion anti-tumour agents

    Miller, Sian Elisabeth (1991)

    Doctoral thesis
    University of Canterbury Library

    Reported here is a study of the solution chemistry of the anti-cancer drug cis-dichloro-diammineplatinum(II), cis-[PtCl₂(NH₃)₂]. In view of uncertainties in literature values of rate constants and in reaction conditions for the reactions of cis-[PtCl₂(NH₃)₂], the kinetics of the first acid hydrolysis step of cis-[PtCl₂(NH₃)₂] are reinvestigated in HClO₄ media, as well as the kinetics of the second hydrolysis step. All the kinetic investigations in this thesis are made using a DMS100 UV - visible spectrophotometer, using the changes in absorbance to monitor reactions. The nature and rate constants for the hydrolysis of cis-[PtCl₂(NH₃)₂] and the anation kinetics of the products under a variety of pH and ionic strength conditions are investigated, such as the kinetics of the base hydrolysis of cis-[PtCl₂(NH₃)₂] and its rates of hydrolysis over a wide pH range. The kinetics of the reactions of some of these hydrolysis products with a variety of ligands, some physiologically relevant and some not, such as chloride ions, sodium hydrogen malonate, glycine and ortho-phenylenediamine, are also investigated. In order to model the situation in vivo as closely as possible, a technique involving the combination of the UV - visible spectrophotometer with a pH-stat is used extensively. This enables the pH to be kept constant while a reaction in progress is being monitored. The likely distribution of platinum(II) species present in blood plasma and inside a cell is thus calculated as a result of these investigations. A possible role for metal ions in accelerating both the acid and base hydrolyses of cis-[PtCl₂(NH₃)₂] is investigated, although metal ions found in vivo are found to have no effect. The crystal structure of the product of the reaction between cis-[PtCl₂(NH₃)₂] and HgCl₂ is reported. The effect of mixtures of aqueous and non-aqueous solvents on the rate of hydrolysis of cis-[PtCl₂(NH₃)₂] was investigated as well as the kinetics of the first acid hydrolysis step of cis-[PtBr₂(NH₃)₂] and the bromide anation of cis [PtBr(NH₃)₂(OH₂)]+. As a result of this experimental work, attempts were made to extrapolate the results of these kinetic investigations, all carried out under stringent reaction conditions, to the possible reactions of cis-[PtCl₂(NH₃)₂] in vivo.

    View record details
  • Manufacturing technology management : key issues in the adoption, implementation and evaluation of advanced manufacturing technology

    Suresh, Balan (1994)

    Doctoral thesis
    University of Canterbury Library

    Over the past decade, the declining competitiveness of U.S. and European manufacturers had received considerable attention. Various studies have documented their weakening competitive position in global markets; the decline of their manufacturing base; and the continued closure of manufacturing plants in U.S. and Europe. Attention has been focused on manufacturing strategy and technological innovations in manufacturing as providing possible solutions to these growing problems. The adoption and implementation of new manufacturing technologies, known collectively as advanced manufacturing technology (AMT), has offered the promise of successfully competing in global markets. Specifically, these technologies have offered advantages in the areas that U.S. and European manufacturers need to address: flexibility, quality, shorter product life cycles, and shorter product development cycles. However, there are two major concerns: (1) U.S. and European manufacturers have been slow to adopt advanced process technology, and (2) those firms which did adopt these new technologies have had limited success in their implementation. In spite of its growing importance in manufacturing, management generally has limited experience with AMT and few guidelines to assist them in the transition from the factory of today to the factory of the future. This research study aims to provide an in-depth, integrative approach to addressing the issues involved in the adoption, implementation and evaluation of AMT by focusing on the experience of organisations pursuing a strategy of automation. Using a multiple case research methodology at plant level, the first part of the study investigates the reasons why European firms choose to adopt advanced manufacturing technologies and the decision making process involved in justifying them. In addition, this study identifies obstacles to justification and provides an understanding of how firms have either ignored or overcome these obstacles. The decision to adopt AMT is only the first step in becoming or remaining competitive. Such technologies need to be successfully implemented to achieve desired benefits. The study also investigates how firms managed their AMT implementation and the obstacles that were encountered. In addition, those factors that contribute to or impede the successful implementation of AMT are identified. The difficulties of performing post-implementation evaluations by these firms are also examined. Emphasising the use of automation as a management decision concerned only with manufacturing is not sufficient. Wider issues in the management of manufacturing technology also need to be addressed. This study highlights the importance of top management involvement in new technology development, time-based competition, and outsourcing of technology in the management of manufacturing technology. It is hoped that by offering general explanations of the key issues in the management processes of adoption, implementation and evaluation of AMT, management will be assisted in their future efforts in dealing with these processes. The participating firms identified both individual and synergistic benefits from the application of AMT in the competitive performance measures in manufacturing, cost, quality, delivery, and flexibility. They also underscored the importance of incorporating technology management issues while formulating business strategies, because these issues were believed to influence the business performance measures, profitability level, generation of increased sales, and creation of new opportunities and facilities. Using questionnaire surveys of the participating firms, the second part of this study explores the relationships between the management processes of AMT and performance measures in manufacturing, and between some factors of effective management of technology identified in this study, and the business performance measures of a firm. Tests of hypotheses formulated confirm that the perceived benefits in manufacturing performance could be achieved. Additional statistical analyses show that, through effective management of technology, the business performance measures of a firm could be improved.

    View record details
  • The decomposition of woolscour and fellmongery sludges

    Williamson, Wendy May (1998)

    Doctoral thesis
    University of Canterbury Library

    This thesis investigated two industrial sludges, a woolscour sludge and a fellmongery sludge. The sludges represent material removed during the clarification of effluent arising, respectively, from the washing of greasy wool and the dehairing of sheepskins for leather manufacture. The aims of the study were to (i) determine the degree to which the wool scour and fellmongery sludges decompose, (ii) to describe the probable constraints upon sludge decomposition and (iii) to assess the likely consequences of sludge decomposition in a soil system. Most experiments were performed at a microcosm scale. The extent to which the woolscour and fellmongery sludges decomposed and the constraints upon their decomposition were determined using net-N mineralisation. An assessment of the consequences of sludge decomposition included leachable mineral N and an estimation of the amount of microbial biomass (MB) in sludge-amended soils. The MB was estimated using the fumigation-extraction method. Wool scour sludge mineralised only 9 % of its initial total N (i-TN) during decomposition at 22°C, however N mineralisation increased dramatically to 40 % i-TN when the sludge was incubated at 50 DC. Fellmongery sludge mineralised 52 % i-TN at 22°C, but showed no net-N mineralisation at 43 or 50°C. When the sludges were decomposed in an anaerobic atmosphere, the fellmongery sludge mineralised only 15 % i-TN after 108 days. Anaerobic conditions did not greatly affect the decomposition of woolscour sludge, which mineralised 5 % i-TN in 108 days. It is suggested that different pools of the soil MB were involved in the decomposition of the wool scour sludge and the fellmongery sludge. One of the consequences of the rapid decomposition of fellmongery sludge was the leaching of water-soluble mineral N. During the decomposition of surface-applied fellmongery sludge (at a rate equivalent to 350 kg N ha-¹) to leaching columns (5-cm x 15-cm height), 25 to 39 % of the applied N was leached as mineral N in 100 days. Most of the mineral N leached was present as nitrate (68 to 93 %), which exceeded 10 mg nitrate L-1 of leachate for 45 to 80 days. The amendment of soil with wool scour and fellmongery sludge, at a rate equivalent to 200-kg N ha-¹ and incubated in microcosms, caused a dramatic decrease in the MB, such that the level of MB was below detection using the fumigation-extraction technique after a year of soil incubation. When soil was amended with wool scour and fellmongery sludges in the field and the soil sampled ten months post-amendment, the MB had also decreased, although the effect was weaker than that seen in the microcosm study. In addition, less N was mineralised from wool scour and fellmongery sludges decomposing in their respective sludge-amended soil, than when decomposed in nonamended soils. Together, these results indicate that the application of woolscour and fellmongery sludges to soil has the potential to significantly impede nutrient cycling through the reduction of microbial function. Fellmongery sludge showed inconsistent results for its value as a fertiliser. On the one hand, fellmongery sludge-amended soil that had been heavily leached for 105 days prior to ryegrass seeds being planted, produced significantly more grass (165 mg (dry weight; dw)) than from the non-amended, leached control soil (106 mg (dw)), after 50 days of grass growth. The enhancement of grass growth was seen more strongly when already established ryegrass received a fresh application of fellmongery sludge, at a rate equivalent to 350-kg N ha-¹. In 20 days of grass growth, the amended soil produced 375 mg (dw) of ryegrass, whereas the non-amended soil produced 103 mg (dw). These results indicated that fellmongery sludge could provide nutrients that promoted the growth of ryegrass. However, on the other hand, ryegrass harvested from fellmongery sludge-amended soil was enriched with nitrate (5.9 % of the TN was nitrate for grass grown on the amended-soil but only 1.5 % from non-amended soil). The ryegrass growing on the soil re-amended with the fellmongery sludge all died after the 20 days harvest, whereas the grass on the non-amended columns continued to grow. In addition, cucumber seeds failed to germinate in the presence of fresh fellmongery sludge. Two case studies were carried out concurrently with this research. In the first, it was found that the long-term practice (> 15 years) of burying excess woolscour sludge in soil had decreased the MB-N of wool scour waste-amended soil from 4.0 % to 1.4 % of soil N. In the second case study, it was found that mixtures of woolscouring and fell mongering wastes that had received 90 days of composting treatment were unsuitable media in which to grow cucumber seedlings, which indicated that the composting treatment of these wastes had been unsuccessful. The unsuccessful formation of compost during these trials was considered to be due, mainly, to technical problems.

    View record details
  • Seismic performance of retrofitted reinforced concrete bridge piers : laboratory testing of the proposed Thorndon Overbridge retrofit scheme

    Presland, Robert Andrew (1999)

    Doctoral thesis
    University of Canterbury Library

    This thesis describes the experimental set-up and testing of two scale models of particular piers of the Thomdon Overbridge incorporating the proposed retrofit measures to be included in the structure. Each test specimen represented the structural model developed for the analysis of the Overbridge structure incorporating the proposed retrofit designs for each pier. Modelling of the boundary conditions of the structural model were incorporated into the test specimens by including elements to represent the variable stiffness properties of the piles in the structure under tension and compression. Testing revealed potential deficiencies with the original structure and the proposed retrofit designs which would have limited the seismic performance of the retrofitted piers. Repairs to the test specimens showed improved seismic performance could be obtained and recommendations for the proposed retrofit designs are included. A method for assessmg the capacity of bridge columns containing curtailed longitudinal reinforcement is proposed following the results of the test programme. This method provides a lower bound strength for columns which compares well to the experimental results from the two test specimens. Flexural strength enhancement over the ACI ideal moment is known to occur due to assumptions made when determining the ACI ideal moment. Expressions are presented which predict the ACI ideal moment and the maximum flexural strength of rectangular shaped columns. The observed shift in the critical section of a column, when confined by an adjacent member, and its influence on the flexural strength enhancement is investigated. A statistical analysis of a number of experimental colunm tests has indicated this to be a significant component of the flexural strength enhancement observed during testing.

    View record details
  • Seismic pounding of adjacent multiple-storey buildings considering soil-structure interaction and through-soil coupling

    Rahman, Amar Mahmood (1999)

    Doctoral thesis
    University of Canterbury Library

    Structural pounding may be defined as the collisions occurring between adjacent dynamically excited structures which lack a sufficient separation gap between them. Extensive theoretical and experimental studies have been conducted to investigate this phenomenon. However, the majority, if not all, of these studies fail to consider the flexibility of the soil upon which these structures are constructed. This study aims to investigate the degree of approximation inherent in previous pounding studies which neglected this important feature. In this study, two aspects of soil flexibility effects on dynamic structural response were investigated: the influence of the supporting soil properties on the individual structures (soil-structure interaction) and the through-soil interaction between the foundations of the adjacent structures. Two structural configurations of reinforced concrete moment-resistant frames were considered: the case of two adjacent twelve-storey frames and the pounding of a twelve- and six-storey frames. Four cases of external excitation were investigated: two actual earthquake records applied from two directions each. A nonlinear inelastic dynamic analysis software package developed at the University of Canterbury has been utilized in this study. Suitable numerical models were developed for the through-soil interaction phenomenon and for the structures, which were designed in accordance to the relevant New Zealand design codes. Soilstructure interaction was represented by means of existing models available in the literature. Various separation gaps were provided and the results were compared with the no pounding case. Storey-level impacts only were considered. The pounding response in which soil flexibility was accounted for was compared to the fixed base response for each of the separation gaps incorporated in this study. A high variation in the results was witnessed, indicating the significance of consideration of soil flexibility effects. In addition, the importance of excitation direction was highlighted in this study. The relative storey accelerations were more dependent on the characteristics of the excitation rather than on the magnitudes of the impact forces. Recommendations were proposed which aim towards the generalization of the results of this study.

    View record details
  • Ring laser dynamics

    King, Benjamin Thomas (1999)

    Doctoral thesis
    University of Canterbury Library

    The departure of the behaviour of large ring laser gyros from the ideal is examined. A detailed description of the experimental operation of large ring lasers is provided along with several new innovations in equipment layout, data collection and especially in data reduction. The limits on gyro performance due to noise are investigated. A review of literature regarding the fundamental limit placed on gyro resolution is provided. This limit is due to spontaneous emission in the gain medium of the laser and it is demonstrated that our ring lasers approach this quantum limit. Two entirely independent methods for evaluating the quantum noise induced linewidth are demonstrated to agree well. One of the methods, which uses a second order autoregressive model, is able to make accurate linewidth estimates in sub-second gate times. A complex model is proposed which accounts for specific observed light scattering phenomena within a ring laser. This model is compared with dual beam data taken from C-I and is able to describe frequency shifts and waveform distortion accurately. The model also performs favourably when describing locking profiles for low rotation rates and externally induced perimeter modulation. When locked to an external signal the ring laser is found to be an extremely sensitive low frequency vibration detector. The commissioning of a very large (14 m perimeter) prototype ring laser gyro, GO, is described along with a comparison with the smaller ( 4 m perimeter) gyros C-I and C-II. This prototype has proven to be an invaluable testing ground for designs and techniques to be used on a proposed high precision 16 m perimeter gyro named the Grossring (G).

    View record details
  • Sedimentology, coal chemistry and petrography of the Cretaceous Morley coal measures and the Eocene Beaumont coal measures, Ohai Coalfield, South Island, New Zealand.

    Shearer, Jane Christine (1992)

    Doctoral thesis
    University of Canterbury Library

    Several kinds of data from the Cretaceous Morley and Eocene Beaumont Coal Measures at Ohai Coalfield were integrated in order to develop models for sedimentary elastic deposition and mire formation. These data comprise lithostratigraphic relationships at outcrop and basin scale and information on coal chemistry, petrography and palynology. Results indicate that although deposition of both Morley and Beaumont Coal Measures were tectonically controlled by the development of sedimentary sub-basins, Cretaceous mires and sedimentary regimes differ from those of the Eocene. Although the data available at Ohai Coalfield are insufficient for interpretation of fluvial channel planform, other characteristics of the sedimentary environments can be deduced. Accumulation of the Morley Coal Measures occurred in two types of non-contemporaneous environment, 'S'-environments, in which widespread sand was deposited by fluvial channels and few mires developed, and 'C'-environments in which only fine-grained elastic deposition occurred and mires were extensive and persistent. Three environments, which were sometimes contemporaneous, have been identified in the Beaumont Coal Measures. In Beaumont 'S'-environments, sandy elastic sediment was deposited widely by fluvial channels whereas in the 'C'- and 'C-S'-environments, mires developed and sedimentation in shallow lakes and streams was widespread. In the 'C'-environments channels carried mud with little sand but in the 'C-S'-environments sand deposition was more common. Morley mires, which were larger and longer-lived than Beaumont mires, were rarely flooded and may have been domed. In contrast, Beaumont mires were frequently flooded and probably not domed. Most Morley mires developed in environments with widespread mires drained by low energy streams. In contrast high energy fluvial activity was more common in Beaumont mire-forming environments; Beaumont mires are inferred to have frequently developed on lake margins. Palynological evidence indicates that the Morley floral assemblage was dominated by gymnosperms whereas both angiosperms and gymnosperms formed significant proportions of the Beaumont flora. The information available on Morley coal allows development of a model for peat accumulation. Peat accumulation was influenced by a number of interdependent parameters including water table level, nutrient supply and acidity. In response to environmental conditions two different peat types formed. At the base, top and margins of mires peat was generally woodier, less degraded and less oxidised. In contrast, peat in the mire centres suffered both more non-oxidative degradation as well as oxidation and contained less woody material. As mires developed, the initially diverse gymnosperm flora became dominated by the podocarp Phyllocladidites mawsonii however this change in vegetation did not affect the character of the peat.

    View record details
  • Magnetooptical spectroscopy of matrix-isolated free radicals

    Langford, Vaughan S. (1997)

    Doctoral thesis
    University of Canterbury Library

    This Ph.D. thesis presents the results of magnetooptical spectroscopic investigations of free radicals isolated in Ar matrices at cryogenic temperatures (≤20 K). The experiments required development of a high-resolution simultaneous magnetic circular dichroism (MCD) and absorption spectrometer, MOD4. Design, construction and commission of MOD4 comprised a significant portion of this project, and its description constitutes a substantial part of the 'Experimental' chapter of the thesis. The results of matrix-isolation experiments on the first-row radical monohydrides, CH, NH (and ND) and OH (and OD), and the theoretical analyses of the data comprise the main body of this thesis, and are presented in three chapters. Temperature and magnetic-field dependencies of the MCD and absorption over the ranges T≈1.4 –17 K and B = 0 to ∼ 4.5 T, are interpreted in terms of a spin-orbit (SO) –crystal-field (CF) model. The data are analysed by the application of quantum-mechanical and group-theoretical techniques, utilising moment analysis and (in the case of NH) spectral simulation. These allow SO and CF parameters to be extracted. Assignments of structure observed in the spectra have also been attempted. Radical monoanions and monocations of buckminsterfullerene (C₆₀) have been investigated in Ar matrices using MCD and absorption spectroscopy, over the ranges T≈1.6 –30 K and B = 0 –4 T. Preliminary conclusions have been drawn from these data, concerning the symmetry of the molecules, but more experimental and theoretical work needs to be done. Ferricenium, the radical cation of ferrocene, has been isolated in Ar (with a SF6 counter-ion) for the first time. Preliminary MCD and absorption data are presented, and show well-resolved vibronic structure; assignments to totally symmetric and Jahn-Teller-active vibrational overtones are made.

    View record details
  • Theoretical studies of anisotropic ion transport systems

    Grice, Stephen T. (1993)

    Doctoral thesis
    University of Canterbury Library

    Ab initio calculations of potential energy surfaces have been applied to a range of chemical problems. Specifically these methods have been applied to the Diels-Alder reaction between butadiene and acetylene. The structure of the reactants, the Cs transition state, and the products have been calculated. The transition state geometry and energy is analysed in terms of orbital interactions and distortion energy relative to the separated reactants. The increase in energy of the filled π-orbital of acetylene not involved in bonding changes is the major contributor to the activation energy for the Diels-Alder reaction of butadiene with acetylene being greater than that found between butadiene and ethylene. Comparisons with a series of other related Diels-Alder reactions are discussed. The calculation of interaction potentials of a series of open shell ions with helium has been combined with moment method calculations to determine the ion transport properties of systems that involve anisotropy. First the theory of the moment methods used to calculate the transport properties of ions in dilute gases is reviewed. The theory for spherically symmetric ions in a spherically symmetric gas is briefly discussed, followed by a review of the recent specialisation of the theory for diatomic ions in diatomic gases to atomic ions in a diatomic gas. The theory of spherically symmetric systems is then applied to open shell ions that have orbital angular momenta greater than zero. Any theoretical treatment of the ion transport properties of such ions must recognise that more than one collision channel is available to the collision partners. Two classical models are developed that involve non-adiabatic transitions between these collision channels during a collision and between collisions. The models are used to study the mobilities of the following ions: C⁺ (² P), C+* (⁴P), N⁺(³ P), O⁺ (48), O⁺* (± P), Si⁺(²P), Si⁺* (⁴P). A summary and discussion is given. The theory of atomic ions in diatomic gases is then applied to the Li⁺ — N₂ and the Li⁺ — CO systems. Ab initio calculations of the rigid rotor potential energy surfaces for these systems are followed by calculations of the transport cross sections and transport coefficients. Comparisons of the transport coefficients derived from existing potential energy surfaces show that the potential energy surfaces calculated in this work are significantly better, and as good as can be derived from comparison of the theoretical and experimental ion transport results.

    View record details
  • Seismic behaviour and design of reinforced concrete interior beam column joints

    Lin, Cheng-Ming (1999)

    Doctoral thesis
    University of Canterbury Library

    The physical model of shear transfer mechanism in reinforced concrete beam-column joints in which the New Zealand Concrete Structures Standard NZS 3101: 1995 is based provides a good insight into the seismic behaviour of joints. However there are still some issues observed in the laboratory work that can not be fully explained with such model. This research project is aimed at improving the understanding of the seismic behaviour of joints. The research work seeks the endorsement of the design recommendations for interior joints given by the Concrete Structures Standard. The lower bound theorem of plasticity was applied to find the internal force trajectories within the joint panel. The diagonal compressive stress field of the joint was modeled with variable angle struts-and-ties. Relative importance of parameters influencing the shear strength of the joint panel was identified through the series of parametric analysis. The database consisting of 60 tests were processed to be used in conjunction with the analytical work. It was found that a clear trend exists between the ductility of the frame subassemblies and the joint shear stress ratios equivalent to a reference joint. This relationship was used to derive the design recommendations for the requirements of horizontal joint shear reinforcement of joints of ductile frames and limited ductility frames. An experimental programme was conducted to validate the analytical results with particular emphasis given to parameters that were found to be in disagreement between the analysis and the current design recommendations. Eight cruciform subassemblies were tested under simulated earthquake loading. Precast concrete was incorporated in the fabrication of the test units to simulate the design practice. There are five units in which beam bars are lumped at the top and bottom beam chords, while three units incorporate distributed longitudinal beam reinforcement. Grade 500 reinforcing bars were used as beam and column longitudinal reinforcement in all units. Test results showed good agreement with the analytical model within reasonable accuracy. Some of the important findings are summarized below. First, column compressive loads are not always beneficial to the joint strength. When the column axial load level exceeds 0.3fcAg, it becomes detrimental to the joint. Second, according to the results obtained in this study, the design recommendations given by NZS 31 O 1: 1995 are conservative in general and could be relaxed, except for some rare cases. Third, the horizontal joint reinforcement is strongly influenced by the ratio Vjh / f c rather than by the bond force of the longitudinal beam bars. Forth, the requirement of horizontal joint reinforcement given by NZS 3101: 1995 for joints in which the amount of top and bottom beam bars is unequal was found to be unduly stringent. Fifth, the shear strength of the joints in which beam bars are distributed along the web is very similar to that of the conventionally reinforced joints. Therefore, no relaxation of amount of horizontal joint reinforcement can be expected when using this design alternative. Test results showed that the theoretical model established in this study is able to predict the joint strength in correlation with the ductility. Joint design procedures based on the traditional forced based and displacement based design are discussed in this work. The effect of using high-grade reinforcement on the bond strength within the joint is also studied. Test results and theoretical predictions conclusively showed that the yield drift of the frame subassembly becomes large when Grade 500 longitudinal reinforcement is incorporated. As a result, full ductility can seldom be achieved before reaching the interstorey drift limitation of 2.5% given for the ultimate limit state by the loadings code, NZS 4203: 1992. Drift limitations are expected to control the design of reinforced concrete moment resisting frames when Grade 500 reinforcement is used as longitudinal bars in columns and beams. It is suggested that, except for low-rise structures in which the drift limit can be easily met, moment resisting frames designed using Grade 500 bars be designed only for limited ductility response.

    View record details
  • IPSO reaction studies of aromatic systems

    (1994)

    Doctoral thesis
    University of Canterbury Library

    The first section of this thesis is concerned with exploring the mechanism of reaction with nitrogen dioxide of a series of unsymmetrically substituted phenols and their derived 4-nitrocyclohexa-2,5-dienones. The effect the substituents have on the regioselectivity of NO₂ reaction on the phenols is examined by analysis of the types of products and in the case of 2,3,4,6-tetramethylphenol (32) it was possible to undertake 15N-labelling studies to unambiguously ascertain the mode of reaction of NO₂. It is shown that the regiochemistry is dependent on the electron withdrawing or electron donating nature of the 3-substituent in the series of phenols studied, specifically 4-chloro-2,3,6-trimethylphenol (31) 2,3,4,6-tetramethylphenol (32) and 3-chloro-2,4,6- trimethylphenol (33). The second section of this thesis is concerned with examining the reactions of 1,4,5,8-tetramethylnaphthalene (21), 1 ,8-dimethylnaphthalene (37), 1-methylnaphthalene (59) and as described in Appendix I the reaction of benzene with tetranitromethane in the presence of light as an activating source to generate the charge transfer complex. The photoaddition of tetranitromethane to aromatics has been shown to give nitro/trinitromethyl, nitrito/trinitromethyl, and hydroxy/trinitromethyl adducts. Also observed were some nitro or hydroxyl cycloadducts in which a nitro group formally associated with a trinitromethyl group is involved in a thermal 1,3-dipolar addition across an alkene system. Tetranitromethane in the presence of an aromatic system and light (≥435 nm) fragments to a trinitromethanide ion (O₂N)₃C-, •NO₂ while the aromatic transfers an electron in the charge transfer process to generate a radical cation. The radical cations are then attacked initially by the very reactive trinitromethanide ion and secondly by •NO₂. This gives rise to the formation of a variety of adducts. The nature of the radical cation is crucial in determining the position of attack of the trinitromethanide ion. In conclusion this work has shown that the relative atomic charges of the aromatic radical cations are important in making an assessment of the likely site(s) of the trinitromethanide attack on that radical cation, but that steric interactions with ipso, peri and vicinal substituents to the reaction site may dictate the overall course of the reaction. Throughout the thesis extensive use is made in product structure determination of single crystal X-ray analysis and in all 23 crystal structures are presented.

    View record details
  • Seismic design of reinforced concrete beam-column joints with floor slab

    Cheung, (Patrick) Pak Chiu (1991)

    Doctoral thesis
    University of Canterbury Library

    Beam-column joints are addressed in the context of current design procedures and performance criteria for reinforced concrete ductile frames subjected to large earthquake motions. Attention is drawn to the significant differences between the pertinent requirements of concrete design codes of New Zealand and the United States for such joints. The difference between codes stimulated researchers and structural engineers of the United States, New Zealand, Japan and China to undertake an international collaborative research project. The major investigators of the project selected issues and set guidelines for co-ordinated testing of joint specimens designed according to the codes of the countries. The tests conducted at the University of Canterbury, New Zealand, are reported. Three full-scale beam-column-slab joint assemblies were designed according to existing code requirements of NZS 3101:1982, representing an interior joint of a one-way frame, an interior joint of a two-way frame, and an exterior joint of a two-way frame. Quasistatic cyclic loading simulating severe earthquake actions was applied. The overall performance of each test assembly was found to be satisfactory in terms of stiffness, strength and ductility. The joint and column remained essentially undamaged while plastic hinges formed in the beams. The weak beam-strong column behaviour sought in the design, desirable in tall ductile frames designed for earthquake resistance, was therefore achieved. Using the laws of statics and test observations, the action and flow of forces from the slabs, beams and column to the joint cores are explored. The effects of bond performance and the seismic shear resistance of the joints, based on some postulated mechanisms, are examined. Implications of the test results on code specifications are discussed and design recomendations are made.

    View record details
  • Extensible optical music recognition

    Bainbridge, David (1997)

    Doctoral thesis
    University of Canterbury Library

    The aim of Optical Music Recognition (OMR) is to convert optically scanned pages of music into a versatile machine-readable format. Existing work has achieved this aim for restricted sets of music notation. Here we investigate the design of an extensible OMR system. Music notation is characterised by intricate features which prove too complex for current computer systems to recognise in a single step. A common methodology in OMR systems is to detect simple primitive shapes which are then assembled into the intricate musical features. However, developing a system capable of processing an extensible set of notation is problematic because there is no limit to the musical shapes that can occur. This thesis deals with the issue by combining a specially designed programming language for primitive detection, a user-configurable knowledge-base for primitive assembly, and an object oriented interface for musical semantics. In doing so, the design is capable of processing not only an extensible set of shapes within one notation, but a variety of notations, such as common music notation, plainsong notation, and tablature. The specially designed programming language eliminates the need for repetitive descriptions, and consequently the code is concise. Grammar rules in the knowledge-base provide a flexible medium in which the valid taxonomy of musical features can be expressed. Finally, the object oriented interface provides a mechanism that can be tailored to encode the semantics of a specific musical notation. Within this framework, the thesis investigates six important steps in the OMR process-staff detection, musical object location, image enhancement, primitive detection, primitive assembly, and musical semantics. Existing work is refined and new algorithms are developed where appropriate. The thesis concludes by comparing the performance of two OMR configurations aimed at reliable matching. Both take approximately 10 minutes to process an A4 page of music using a Digital Celebris GL 5133, with an overall accuracy rate that exceeds 96%.

    View record details
  • Studies in the concentrations and chemistry of cadmium in the environment

    Kim, Nicholas D. (1990)

    Doctoral thesis
    University of Canterbury Library

    Seven surveys were conducted in the city of Christchurch (New Zealand) in order both to obtain comprehensive data describing the concentrations of cadmium in the environment, and determine factors likely to influence these concentrations. In three of the surveys - examining cadmium concentrations in air, riverwater and horse-chestnut leaves - samples were collected over long time periods. Levels of cadmium in dust and soil, house-dust, commercial products and foods were examined in the other four surveys. Concentrations of copper, lead and zinc were also measured in many cases. Cadmium adsorption by - and mobility in - a Christchurch soil, weathering of a cadmium-containing paint and galvanized-iron, the behaviour of cadmium in samples being sequentially extracted, and speciations of cadmium in soils, road-dusts, house-dusts riverwater, and plastics were also studied. High levels of cadmium were found in road-dust in the immediate vicinity of some industrial operations, but concentrations in the wider Christchurch environment were generally low. House-dusts contained higher concentrations of cadmium than typical external dusts. Cadmium concentrations in some commercial products were very high; however, there appeared to be little risk of cadmium being significantly mobilized during the use of most of these products. Probable daily intakes of cadmium were estimated. Numerous factors influenced the levels of cadmium in the various materials examined. A Christchurch soil strongly adsorbed cadmium and the mobility of cadmium in this soil was low. Reagent selectivity for the forms of cadmium during sequential extraction was in some cases good and in some cases poor; little redistribution of cadmium occurred between phases during sequential extractions. Various factors were found to effect the adsorption and mobility of cadmium in soil, the outcome of each sequential extraction, and the weathering of cadmium from cadmium-containing paint and galvanized-iron.

    View record details
  • Lithostratigraphy, palynostratigraphy and basin analysis of the late Cretaceous to early Tertiary Paparoa Group, Greymouth Coalfield, New Zealand

    Ward, Simon David (1997)

    Doctoral thesis
    University of Canterbury Library

    The Paparoa Group of the Greymouth Coalfield, (West Coast, South Island, New Zealand) comprises a wholly terrestrial sequence of alternating fluvial and lacustrine strata deposited in a Late Cretaceous to Early Tertiary rift basin (the Paparoa Basin). Stratigraphic and tectonic evolution of the Paparoa Basin was determined from the lithologic record of 200 drillholes, and chronostratigraphic control was obtained from palynological identification of the Cretaceous-Tertiary Boundary (KTB). Basin fill comprises three lithosomes, which were distinguished using lithofacies and geophysical log character. Coal measure lithosomes comprise pebble-cobble conglomerate, poorly sorted carbonaceous sandstone, siltstone, carbonaceous mudstone and coal, and represent fluvial and mire environments. Mudstone lithosomes comprise massive silty mudstone with rare plant fragments and freshwater bivalves, and represent lacustrine environments. Transitional lithosomes comprise coarsening upwards packets of moderate-well sorted fine to medium non-carbonaceous sandstone and rare conglomerates interbedded with massive mudstone. Lithofacies and unit geometry indicated these strata were deposited as progradational deltas in shallow lakes. Lithostratigraphic unit definitions were revised in accordance with the lithesome framework. Five Formations and five members were recognised within the reinstated Paparoa Group: Jay Fm.; Ford Fm. (including the Ford Transitional Member); Rewanui Fm. (comprising Rewanui Coal Measure Member, Waiomo Mudstone Member and Morgan Coal Measure Member); Goldlight Fm. (including the Goldlight Transitional Member) and Dunollie Fm. The Ford and Goldlight Transitional Members are newly established to incorporate transitional lithosomes within the Ford Fm. and Goldlight Fm. Correlation of all units below the Rewanui Coal Measure Member (CMM) was revised, with Morgan CMM and W aiomo MM in the west of Greymouth Coalfield being transferred to Jay Fm. and Ford Fm. respectively. Revised isopach models for all units (excluding Dunollie Fm.) were constructed using manual and numerical modelling techniques. Maximum present-day thickness of the Paparoa Group (excluding Dunollie Fm.) is 758.6m, and average thickness is 290m. Successively younger units onlap greater areas of basement, and basin geometry becomes simpler with time. Unit thicknesses were decompacted to account for differential burial of 1.75km (west coast) to 4.75km (eastern basin margin). Average thickness reduction during burial was 27%, and there was up to 290m of compaction. Compaction from cover strata deposition was greater than syndepositional compaction within the Paparoa Group. The KTB was identified in 16 drillholes in the western Greymouth Coalfield. Key floral events were the extinction of Tricolpites lilliei and other rare large and/or ornamented angiosperm pollen taxa, and the rise in abundance of Triorites minor. The occurrence of diagnostic taxa was controlled by lithofacies and floral diversity in addition to sample age. Total spore proportions of palynofloras declined across the KTB, though dominant conifer and spore taxa were unaffected. There was a brief decline in angiosperm and conifer diversity c.4m above the KTB. Average palynoflora diversity was unchanged across the KTB, and no mass extinction event was recognised. The interval between the KTB and the upper contact of Rewanui CMM varied throughout the western Greymouth Coalfield, and was controlled by syndepositional faulting. The position of the KTB was predicted in all western drillholes, and major coal seams were found to occur at predictable intervals beneath the estimated KTB position. At the time of the KTB, the western Paparoa Basin was occupied by a floodplain and mire-dominated environment intersected by rivers and associated crevasse splays. Two principal sediment sources fed into the Paparoa Basin. The northeastern axial sandy fluvial system carried granite-derived detritus whereas the northwestern basin margin supplied sand and gravel derived from Paleozoic Greenland Group basement. Sediment flux from both sources declined during lacustrine deposition, however elongate to lobate deltas marked persistent sources of coarse clastic influx into the lake basins. During Goldlight Fm. deposition, sediment transport in the south of the basin was reversed. Minor sediment entered the Paparoa Basin from the southwest, but the eastern basin margin was not a significant sediment source. Tectonic history of the Paparoa Basin was reconstructed from decompacted isopach patterns. Persistent sediment entry points were interpreted as transfer zones between normal faults. Unit thickness patterns were controlled by two orientations of normal faults: WNW/ESE and NNE/SSW. The steep eastern basin margin comprised a NNE/SSW aligned segmented fault zone, whereas there was block faulting along the western basin margin. The southwestern basin margin was flexural. Initial extension was oblique, resulting in reactivation of older (WNW/ESE) structures. Increasing dominance of the NNE/SSW faults during Paparoa Group deposition represented slight anticlockwise rotation of the extension direction. Basin fill style was determined by the interaction of the two sediment sources and the two prominent fault orientations. Structural constraint of sediment entry points, and small scale normal faults within the basin, determined the position of fluvial systems within the basin during coal measure deposition, and the location and geometry of deltaic deposits during lacustrine episodes. The Paparoa Basin is the largest basin within the West Coast Rift System, which comprises a colinear segmented rift system of extensional basins and rift gaps. Extension was initiated in the latest Cretaceous, at c.70Ma, approximately 10Ma after commencement of opening of the Tasman Sea, and related basin formation at Ohai Coalfield and in Taranaki. The West Coast Rift System may therefore contain the record of a previously unrecognised latest Cretaceous tectonic event.

    View record details
  • Precast concrete floor support and diaphragm action

    Herlihy, Michael D (1999)

    Doctoral thesis
    University of Canterbury Library

    Experimental research, engineering analysis and theoretical developments comprise a study in which various interactions between ductile moment resisting frames and precast prestressed hollow core flooring have been examined. The most critical interaction tested involves support behaviour, and the ability of reinforcing details to provide control against loss of support and possible catastrophic flooring collapse under dilation effects. Plastic hinge dilation, also known as elongation or growth, is an inherent property of ductile concrete members when subjected to cyclic plastic deformations. Hence, the performance of floor support details is enveloped by the general design philosophy of seismic resisting structures. In the experimental phase, emphasis was placed on testing support construction joints from contemporary building practice, for direct comparison with special support tie details of known capabilities. The contemporary details were found to exhibit seriously flawed behaviour under monotonic and cyclic loading regimes. Corroborative experiments were undertaken to establish direct shear capacities between typical composite bond surfaces. In particular, these tests addressed the discrepancy that has emerged between direct shear and shear flow strengths. Also, the continuity response of conventional and proposed support detail types was examined. A composite section model was analysed to demonstrate the likely influence of prestressing steel on beam bending strength within a ductile frame environment. Likewise, the probable effects of prestressing steel on beam plastic hinge development were examined, but on a more theoretical basis. Other elements of theory have been presented. These mainly concern the general topic of elastic-plastic response in reinforced concrete elements. The particular focus of this work has been to demonstrate a rational basis to stiffness transition and plastic buckling analysis. The important role of stiffness degradation in dynamic analysis has also been examined. Although ductile moment resisting concrete frames have been emphasised, it is considered that the findings of this thesis are applicable to other structural systems, such as dry joint "hybrid" precast concrete frames and spring connected steel frame structures.

    View record details
  • Theoretical chemistry

    Sudkeaw, Pravit (1991)

    Doctoral thesis
    University of Canterbury Library

    Ab initio Molecular Orbital and Valence-Bond methods and the semiempidcal, AM1 method are applied in the studies of: 1. The proton affinity of diacetylene The gas-phase ion-molecule reaction between diacetylene and a proton was studied theoretically at the MP4SDQ/6-311G** level. The geometries, calculated harmonic vibrational frequencies and the proton affinity of the most stable structures are compared. The results from this study are supported by selected ion flow tube measurements and are compared with other calculations 2. The gas-phase reaction of CH₃CN and CH₃⁺. The reaction between CH₃CN and CH₃⁺ was studied at the MP4SDQ/6-31G* level of theory in order to determine the products and establish the multistep dissociation pathway of the reaction. The location and height of the transition states in the process is used as a criteria for the feasibility of the proposed pathway. The result is compared with the expediential and theoretical studies of the same system done by Wincel and coworkers [146]. 3. The geometries and force constants of small-sized organotin compounds The calculations on 12 small-sized organotin compounds were done at the HF/3- 21G* level of theory. The objective of this study was to provide the force constants of SnX and X-Sn-Y types for the use in Molecular Mechanic calculations of organotin compounds. The calculated geometries and harmonic vibrational frequencies of stannane and methyl stannane are compared with experimental results in order to measure the reliability of the calculations. 4. The chemical properties of CnO, CnO⁺, CnHO⁺, CnS, CnS⁺ and CnHS⁺ species in the instellar clouds CnO and CnS when n = 2 and 3 have been reported to be found in some interstellar clouds. These species in such environments are subjected to ionization and protonation processes. Theoretical studies of these species were done at the MP4SDQ/6-311G** level of theory. The calculations suggest that these species are more stable in protonated forms and could be intermediates of some steady state processes. 5. Theoretical study of C₆H₄+ formation in acetylenic flames C₆H₄⁺ has been detected as an intermediate in acetylenic flames. The semiempirical AM1 method was used to determine the most stable products and to establish a chemical mechanism of the reaction between C₄H₂⁺ and C₂H₂. The results from AM1 method were refined by ab initio calculations at the HF/4-31G andMP4SDQ/6-31G* level. From this study, only chemical pathways involved acyclic structure isomers are feasible. 6. A Valence-Bond study of BH2 radical In this study a Valence-Bond program was used on IBM PC/AT microcomputer to study the correlation between the nuclear bond angle and the angle of hybrid orbitals of BH₂. The energies of BH₂ from the Valence-Bond calculations were also compared with the energies from the Molecular Orbital method at the HF, MP4SDQ and CI level with best orbital energy basis sets, 10s6p/2s1p for boron atom and 6s/1s for hydrogen atoms. GAUSSIAN series programs, the MICROMOL package, the GAMESS program, a Valence-Bond program and the MOPAC program were used to perform the calculations.

    View record details