A fast computer program for conformational analysis

We describe a program, called SOBALCAN, that enables us to compute very quickly the rotation hypersurface of a flexible molecule in the “ soft-sphere” approximation. Only those conformations in which the overlap of spheres associated to all pairs of non-bonded atoms is less than a prefixed threshold are computed.     

A computer program for thin walled frame analysis

The paper presents a general purpose computer program capable of analysing any planar frame made up of members which can be categorised as thin-walled members. The approach is based on Vlasov's theory which accunts for coupling between torsion and bending actions. The topic is gaining importance due to the improved techniques of producing cold-formed steel sections which have much higher strength than normal steels. The program is in the form of single-array storage which makes its application easy even by a practicing engineer who cannot go into the details of Vlasov's theory. The program is illustrated by means of an example with complete information about input and output for the particular problem.     

A computer program for three dimensional analysis of buildings

A special purpose computer program for the linear three dimensional analyses of building structures for gravity, lateral and earthquake loads is presented. The building is idealized as consisting of a series of rigid jointed rectangular frame or frame-shearwall substructures interconnected through a rigid floor diaphragm. Finite joint sizes, shear deformations and axial deformation of columns are considered. Three dimensional frequencies and mode shapes are evaluated and a response spectrum approach is used for the dynamic analysis. A front-end processor accepts input data in a conversational mode and in free format. Data input is speeded up by taking advantage of the repetitive nature of frame dimensions, member sizes and loadings.     

Interactive graphics for guyed tower analysis

The interactive graphic features of a special purpose software for the nonlinear analysis of guyed towers are described.     

A computer program for the analysis of matched case-control studies

The use of regression methods for matched epidemiologic studies is discussed. A computer program is given for use in analysis of 1-1 and 1-R matched case-control data as well as the more general stratified analysis, where m cases are matched with n controls in each of K strata. The program permits variable matching ratios. An illustration is given.     

A program for longitudinal load analysis of electric transmission lines

An analysis procedure and computer program are described for the static analysis of electric transmission lines for unbalanced longitudinal loads due to broken wires or differential ice. The nonlinearily of the wires and suspension insulators are considered. A modified Newton-Raphson iteration procedure is used. The input to the program consists of: the physical properties of the transmission line; the ice loading and the location of broken wires. The output consists of the wire tensions and the displacements in the final equilibrium position. The program was developed under a research project funded by the Electric Power Research Institute.     

A computer program for kinematic analysis of three-dimensional cascaded linkage chains

The KIN program analyses the motion of three-dimensional cascaded linkage chains consisting of combinations of four-bar linkage units, axial translation units, and sliders (units confined to motion along a fixed line). Motion can be simulated for any combination of geometrical parameters. The model, the program, input-output features and an application are described. The program is written in PL/1, and can be run in either batch or conversational mode.     

A new computer program for the analysis of pediatric scalar electrocardiograms

The authors report the development and evaluation of a computer program for analysis of pediatric scalar electrocardiograms. The program is an extension of the existing IBM 5890 ECG Analysis Program. It includes extensive age-dependent criteria and tables of limits for ECG parameters. Special pediatric correlative statements are incorporated to direct physician attention to combinations of electrocardiographic findings which may indicate congenital abnormality. The program permits the use of alternate precordial leads V_4R, V_3R, and V₇ in addition to the standard V₁ to V₆. The evaluation shows the program to be 96.8% sensitive and 88.3% specific in detecting abnormal rhythms; a sensitivity of 99.8% and specificity of 96.0% were obtained for detection of abnormalities affecting ECG contour. Program performance is apparently insensitive to choice of precordial leads, but dependent on patient age, improving as age increases.     

A FORTRAN program for multivariate survival analysis on the personal computer

In this paper a FORTRAN program is presented for multivariate survival or life table regression analysis in a competing risks' situation. The relevant failure rate (for example, a particular disease or mortality rate) is modelled as a log-linear function of a vector of (possibly time-dependent) explanatory variables. The explanatory variables may also include the variable time itself, which is useful for parameterizing piecewise exponential time-to-failure distributions in a Gompertz-like or Weibull-like way as a more efficient alternative to Cox's proportional hazards model. Maximum likelihood estimates of the coefficients of the log-linear relationship are obtained from the iterative Newton-Raphson method. The program runs on a personal computer under DOS; running time is quite acceptable, even for large samples.     

Front solution program for transmission tower analysis

A simpler version of the frontal solution technique suitable for solving structures with large number of members is described here. The facilities of the program are brought out with regard to the re-solution and re-design of a large structural problem. It is used here to solve a transmission tower problem and the resulting stress distribution in the main members are discussed.     

Three-dimensional analysis of guyed logging spars

Trees are commonly guyed and used as spars to increase the capacity of cable logging systems in mountainous terrain. Spar response to loading is complex because of nonlinearities due to cable behavior, beam-column loading of the spar, and the geometric effects of large spar deflections. A numerical procedure has been developed to determine spar deformation and the resulting state of stress in the spar and the guylines due to the application of static loads. The Newton-Raphson algorithm is utilized to determine spar position which is denned by force equilibrium. A numerical damper is required to assure convergence. The problem is formulated using the finite element procedures where the spar is treated as an assemblage of three-dimensional beam elements, the guylines are modeled as nonlinear springs, and spar base fixity is provided by a linear rotational spring. The details of the solution method and an example problem are presented.     

Behaviour of guyed transmission line structures under tornado wind loading

Localized severe wind events, in the form of downbursts and tornadoes, are responsible of the majority of transmission line structures failures in many regions around the globe. The wind profiles associated with these events are different than the conventional boundary layer wind profile that is typically used to design the supporting towers. A comprehensive study is presented in this paper to assess and understand the performance of transmission line structures under tornado loading. The study is conducted numerically using a three-dimensional finite-element model and incorporates velocity fields for various tornado scales, which are based on a computational fluid dynamics analysis. The numerical model accounts for the nonlinear behaviour of the conductors, ground-wires, and supporting guys. An extensive parametric study is conducted by varying the location of F4 and F2 tornadoes relative to the transmission line system. The study investigates the variation of the tower members’ internal forces with the tornado locations. It also provides an insight about the structural response of the towers under tornado wind loads. The dynamic effect associated with the translation motion of the tornado is assessed. Finally, the results of the parametric study are used to assess the sensitivity of the members’ peak forces with the parameters defining the location of the tornado relative to the line.     

A computer program for calculating ratio estimates

A computer program is described to calculate ratio estimates for an endpoint measured on patient subunits, such as progression of disease in coronary arteries and extent of dental caries. The program calculates ratio estimates for levels of stratification factors measured in the patient as a unit, e.g. age and sex. Test statistics are computed to evaluate differences in ratio estimates for factors with two levels. A method for making pairwise comparisons for factors with more than two levels is also described, but is not computed by the program. Data from the Veterans Administration Study of Bypass Surgery (Am. J. Cardiol. 40 (1977) 212-225) are used to illustrate the features of the program.     

A computer program for non-linear curve fitting

Recently several techniques for non-linear curve fitting have been developed. The implementation of a non-linear curve fitting procedure is treated for mathematical models in which the linear and the nonlinear parameters are separable. The technique of Golub and Pereyra is used so that a minimization algorithm only for the non-linear parameters is needed. The minimization algorithm of Marquardt has been completed with an eigenvalue analysis. In order to reduce the computation steps the inverses of matrices of the form A + λI are calculated with the eigenvalues and eigenvectors of the matrix A. Of particular interest is the obtained convergence speed and the ease with which the method can be applied.