A frame-invariant scheme for the geometrically exact beam using rotation vector parametrization

While frame-invariant solutions for arbitrarily large rotational deformations have been reported through the orthogonal matrix parametrization, derivation of such solutions purely through a rotation vector parametrization, which uses only three parameters and provides a parsimonious storage of rotations, is novel and constitutes the subject of this paper. In particular, we employ interpolations of relative rotations and a new rotation vector update for a strain-objective finite element formulation in the material framework. We show that the update provides either the desired rotation vector or its complement. This rules out an additive interpolation of total rotation vectors at the nodes. Hence, interpolations of relative rotation vectors are used. Through numerical examples, we show that combining the proposed update with interpolations of relative rotations yields frame-invariant and path-independent numerical solutions. Advantages of the present approach vis-a-vis the updated Lagrangian formulation are also analyzed.

Compressible boundary-layer flow at a three-dimensional stagnation point with massive blowing

The effect of massive blowing rates on the steady laminar compressible boundary-layer flow with variable gas properties at a 3-dim. stagnation point (which includes both nodal and saddle points of attachment) has been studied. The equations governing the flow have been solved numerically using an implicit finite-difference scheme in combination with the quasilinearization technique for nodal points of attachment but employing a parametric differentiation technique instead of quasilinearization for saddle points of attachment. It is found that the effect of massive blowing rates is to move the viscous layer away from the surface. The effect of the variation of the density- viscosity product across the boundary layer is found to be negligible for massive blowing rates but significant for moderate blowing rates. The velocity profiles in the transverse direction for saddle points of attachment in the presence of massive blowing show both the reverse flow as well as velocity overshoot.

Scheme of squares: Part I. Systems formalism for potentiostatic studies

The so-called “Scheme of Squares”, displaying an interconnectivity of heterogeneous electron transfer and homogeneous (e.g., proton transfer) reactions, is analysed. Explicit expressions for the various partial currents under potentiostatic conditions are given. The formalism is applicable to several electrode geometries and models (e.g., semi-infinite linear diffusion, rotating disk electrodes, spherical or cylindrical systems) and the analysis is exact. The steady-state (t→∞) expressions for the current are directly given in terms of constant matrices whereas the transients are obtained as Laplace transforms that need to be inverted by approximation of numerical methods. The methodology employs a systems approach which replaces a system of partial differential equations (governing the concentrations of the several electroactive species) by an equivalent set of difference equations obeyed by the various partial currents.

Scheme of squares: Part II. Systems formalism for sinusoidal perturbations

We extend here the formalism developed in Part I (for the potentiostatic response) to the admittance analysis of the scheme of squares. The results are applicable, as before, to several configurations of the electrode such as the rotating disk or the planar. All that one has to do is “to plug in” the appropriate matrices relating the interfacial concentrations to the fluxes.

A Fuzzy Approximation Scheme for Sequential Learning in Pattern Recognition

An adaptive learning scheme, based on a fuzzy approximation to the gradient descent method for training a pattern classifier using unlabeled samples, is described. The objective function defined for the fuzzy ISODATA clustering procedure is used as the loss function for computing the gradient. Learning is based on simultaneous fuzzy decisionmaking and estimation. It uses conditional fuzzy measures on unlabeled samples. An exponential membership function is assumed for each class, and the parameters constituting these membership functions are estimated, using the gradient, in a recursive fashion. The induced possibility of occurrence of each class is useful for estimation and is computed using 1) the membership of the new sample in that class and 2) the previously computed average possibility of occurrence of the same class. An inductive entropy measure is defined in terms of induced possibility distribution to measure the extent of learning. The method is illustrated with relevant examples.

Simple Coding Scheme For Modular Arithmetic

A dual representation scheme for performing arithmetic modulo an arbitrary integer M is presented. The coding scheme maps each integer N in the range 0 <= N < M into one of two representations, each being identified by its most significant bit. The encoding of numbers is straightforward and the problem of checking for unused combinations is eliminated.

Ionisation and attachment in binary mixtures of SF6-N2 and CCl2F2-N2

Experimental results are presented of ionisation (a)a nd electron attachment ( v ) coefficients evaluated from the steady-state Townsend curregnrto wth curves for SFsN2 and CC12FrN2 mixtures over the range 60 S E/P 6 240 (where E is the electric field in V cm" and P is the pressure in Torr reduced to 20'C). In both the mixtures the attachment coefficients (vmu) evaluated were found to follow the relationship; where 7 is the attachment coefficient of pure electronegative gas, F is the fraction of the electronegative gas in the mixture and /3 is a constant. The ionisation coefficients (amlx) generally obeyed the relationship where w2a nd aAa re thei onisation coefficients of nitrogen and the attachinggraess pectively. However, in case of CC12FrN2 mixtures, there were maxima in the a,,,v,a,l ues for CCI2F2 concentrations varying between 10% and 30% at all values of E/P investigated. Effective ionisation coefficients (a - p)/P obtained in these binary mixtures show that the critical E/P (corresponding to (a - q)/P = 0) increases with increase in the concentration of the electronegative gas up to 40%. Further increase in the electronegative gas content does not seem to alter the critical E/P.

Cross-protection study of the nine serovars of Haemophilus paragallinarum in the Kume haemagglutinin scheme

The cross-protection and haemagglutination-inhibition antibodies present in chickens vaccinated with one of the nine currently recognized Kume haemagglutinin serovars of Haemophilus paragallinarum were investigated. The results confirmed the widely accepted dogma that serogroups A, B, and C represent three distinct immunovars. Within Kume serogroup A, there was generally good cross-protection among all four serovars. However, within Kume serogroup C, there was evidence of a reduced level of cross protection between some of the four serovars. The haemagglutination-inhibition antibody levels generally showed the same trend as with the cross-protection results. This study suggests that some apparent field failures of infectious coryza vaccines may be due to a lack of cross-protection between the vaccine strains and the field strains. Our results will help guide the selection of strains for inclusion in infectious coryza vaccines.

An Adaptive Scheme for Learning the Probability Threshold in Pattern Recognition

The statistical minimum risk pattern recognition problem, when the classification costs are random variables of unknown statistics, is considered. Using medical diagnosis as a possible application, the problem of learning the optimal decision scheme is studied for a two-class twoaction case, as a first step. This reduces to the problem of learning the optimum threshold (for taking appropriate action) on the a posteriori probability of one class. A recursive procedure for updating an estimate of the threshold is proposed. The estimation procedure does not require the knowledge of actual class labels of the sample patterns in the design set. The adaptive scheme of using the present threshold estimate for taking action on the next sample is shown to converge, in probability, to the optimum. The results of a computer simulation study of three learning schemes demonstrate the theoretically predictable salient features of the adaptive scheme.

Electron attachment in binary mixtures of electronegative and buffer gases

The ratio of the electron attachment coefficient eta to the gas pressure p (reduced to 0 degrees C) evaluated from the Townsend current growth curves in binary mixtures of electronegative gases (SF6, CCl2F2, CO2) and buffer gases (N2, Ar, air) clearly indicate that the eta /p ratios do not scale as the partial pressure of electronegative gas in the mixture. Extensive calculations carried out using data experimentally obtained have shown that the attachment coefficient of the mixture eta mix can be expressed as eta mix= eta (1-exp- beta F/(100-F)) where eta is the attachment coefficient of the 100% electronegative gas, F is the percentage of the electronegative gas in the mixture and beta is a constant. The results of this analysis explain to a high degree of accuracy the data obtained in various mixtures and are in very good agreement with the data deduced by Itoh and co-workers (1980) using the Boltzmann equation method.

A knowledge-based clustering scheme

In this paper the notion of conceptual cohesiveness is precised and used to group objects semantically, based on a knowledge structure called ‘cohesion forest’. A set of axioms is proposed which should be satisfied to make the generated clusters meaningful.

Relationship between the Physicochemical Properties of Nonchitinolytic Listeria and Salmonella and Their Attachment to Shrimp Carapace

Listeria and Salmonella are important foodborne pathogens normally associated with the shrimp production chain. This study investigated the potential of Salmonella Typhimurium, Salmonella Senftenberg, and Listeria monocytogenes (Scott A and V7) to attach to and colonize shrimp carapace. Attachment and colonization of Listeria and Salmonella were demonstrated. Shrimp abdominal carapaces showed higher levels of bacterial attachment (P < 0.05) than did head carapaces. Listeria consistently exhibited greater attachment (P < 0.05) than did Salmonella on all surfaces. Chitinase activity of all strains was tested and found not to occur at the three temperatures (10, 25. and 37 degrees C) tested. The surface physicochemical properties of bacterial cells and shrimp carapace were Studied to determine their role in attachment and colonization. Salmonella had significantly (P < 0.05) more positive (-3.9 and -6.0 mV) cell surface charge than Listeria (-18 and -22.8 mV) had. Both bacterial species were found to be hydrophilic (<35%) when measured by the bacterial adherence to hydrocarbon method and by contact angle (theta) measurements (Listeria, 21.3 and 24.8 degrees, and Salmonella, 14.5 and 18.9 degrees). The percentage of cells retained by Pheryl-Sepharose was lower for Salmonella (12.8 to 14.8%) than it was for Listeria (26.5 to 31.4%). The shrimp carapace was found to be hydrophobic (theta = 74.5 degrees), and a significant (P < 0.05) difference in surface roughness between carapace types was noted. There was a linear correlation between bacterial cell Surface charge (r(2) = 0.95) and hydrophobicity (r(2) = 0.85) and initial attachment (P < 0.05) of Listeria and Salmonella to carapaces. However, the same properties Could not be related to subsequent colonization.

Development of a multi-locus sequence typing scheme for avian isolates of Pasteurella multocida.

A total of 63 isolates of Pasteurella multocida from Australian poultry, all associated with fowl cholera outbreaks, and three international reference strains, representing the three subspecies within P. multocida were used to develop a multi-locus sequence typing scheme. Primers were designed for conserved regions of seven house-keeping enzymes - adk, est, gdh, mdh, pgi, pmi and zwf - and internal fragments of 570-784 bp were sequenced for all isolates and strains. The number of alleles at the different loci ranged from 11 to 20 and a total of 29 allelic profiles or sequence types were recognised amongst the 66 strains. There was a strong concordance between the MLST data and the existing multi-locus enzyme electrophoresis and ribotyping data. When used to study a sub-set of isolates with a known detailed epidemiological history, the MLST data matched the results given by restriction endonuclease analysis, pulsed-field gel electrophoresis, ribotyping and REP-PCR. The MLST scheme provides a high level of resolution and is an excellent tool for studying the population structure and epidemiology of P. multocida.

Improving the optimum generalised stop-and-wait ARQ scheme

Instead of waiting for the acknowledgments from all the copies of a single data block sent, as in the optimum generalised stop-and-wait ARQ scheme, the transmitter in the proposed scheme starts sending an optimum number of copies of the next block in the queue, soon after receiving the positive acknowledgment from the receiver, thereby further improving the throughput efficiency.