Generate Input Data Research Articles

A Comparison of Errors in objectively Analyzed Fields for Uniform and Nonuniform Station Distributions

Abstract An error analysis of the Purdue Regional Objective Analysis of the Mesoscale (PROAM) scheme is described. PROAM is an interactive, multiple iteration objective analysis package for surface meteorological data. It utilizes a Gaussian weighting function similar to that of Barnes. A problem with applying interpolation routines to surface data is that the surface station network has a highly nonuniform spatial distribution. Smith and Leslie have shown that this nonuniformity can impact the accuracy of the analysis. The objective of this investigation is to determine quantitatively the contribution that this nonuniformity of station locations has on the analysis of data for two different distributions of stations. Experiments were done by varying the values of important analysis parameters in order to generate error curves for each parameter. Analytic functional representations for pressure and temperature were used to generate input data free of observational error, as well as to produce exact analys...

Dynamics of Articulated Structures. Part I. Theory

ABSTRACT A finite element based method is developed for geometrically nonlinear dynamic analysis of spatial articulated structures; i.e., structures in which kinematic connections permit large relative displacement between components that undergo small elastic deformation. Vibration and static correction modes are used to account for linear elastic deformation of components. Kinematic constraints between components are used to define boundary conditions for vibration analysis and loads for static correction mode analysis. Constraint equations between flexible bodies are derived in a systematic way and a Lagrange multiplier formulation is used to generate the coupled large displacement-small deformation equations of motion. A lumped mass finite element structural analysis formulation is used to generate deformation modes. An intermediate-processor is used to calculate time-independent terms in the equations of motion and to generate input data for a large-scale dynamic analysis code that includes coupled e...

Interactive graphics in structural analysis

Interactive computer graphics which implies a continuous exchange of information between the computer and the user has emerged as a very powerful tool in engineering applications. Computer-aided design (CAD) and computer-aided manufacturing (CAM) have found use in electronic circuit design, manufacturing, mapping, and architectural and engineering planning. Using CAD, a machine part, an electric circuit, or a building plan can be drawn and displayed on a video terminal. The product or plan can then be manipulated, rotated, viewed from different angles, or separated into segments. The graphic and attribute information related to the drawing is stored in a data base, and can be retrieved and modified at any time. At a more sophisticated level of CAD, the data base is used to generate input data for a finite element or another analysis program. This paper presents a brief survey of the CAD scene and the hardware and software available and describes the use of interactive graphics in generating data input for analysis.

Compact formulation of pipe network problems

Solution of problems in water distribution networks usually proceeds in one of two ways: (1) analysis of flows in the links, or (2) analysis of the head at the nodes. In the former case, which is somewhat commoner and has certain computational advantages, the user is usually required to generate input data by defining the set of independent loops in the circuited network in addition to the usual node and link characteristics. Such methods are acceptable for analysis where the topology of the network remains constant. A method is presented here that allows the node and loop equations to be generated automatically from a very simple data file defining nodal stipulations and link characteristics. The equations are reduced to a small set of simultaneous equations involving only the nonbasic or redundant variables. This greatly reduces the memory requirements and also speeds solution of the equations. Either an iterative linear approximation or the Newton–Raphson method may be used to solve the simultaneous equations. The approach is useful in design and optimization studies since it allows links to be deleted and/or restored with automatic generation of the necessary equations. The method may also be used with microcomputers or even pocket computers since the order of the system of equations to be solved is reduced to the number of loops in the system.

Computer-aided manufacture of forging dies by volume building

A system of computer programs for the geomtric description of hot forging is outlined. The purpose of the system is (a) to facilitate the manufacture of EDM electrodes for forging dies with the aid of N.C. machining and (b) to generate input data for computer-aided preform design programmes. The forging geometry is defined as a series of simple volumetric modules which are merged together to form the whole shape required. This approach allows a wide range of forging shapes to be defined and machined, with relatively few simple input instructions. Examples of EDM electrones shaoes for typical forging manufactured with the aid of the system are shown. The N.C. tapes to machine such tapes are obtained after approximately 3 minutes computing time, preceded by not more than 30 minutes data preparation. This represents a considerable saving in time over current methods involving conventional pattern making for the copy milling of electrodes.

MISA—A general purpose fem program

This paper describes the Mitsui Structural Analysis Program System (MISA) using the Finite Element Method, which has been developed and improved by Mitsui Engineering and Shipbuilding Co. Ltd. The program system is designed to have high performance pre- and post-processors and has functions for heat conduction analysis and stress analysis. The paper gives a description of the program system in brief terms, and of its functions of extensive input data generation and output editing in combination with the Multi-level Substructure Method. Two examples which illustrate these features more concretely have been chosen for inclusion in this paper.

Evaluating Waterflood Feasibility in a Complex Reservoir System

Abstract The merging of ideas from inter-dependent geological, geophysical und reservoir engineering interpretations is described as the first step in the study of a complex pinnacle reef reservoir system. The reservoir study process is then followed through the model program selection, input data generation and model testing phases. The interpretation of the 1results from the performance match is described, leading to conclusions regarding reservoir operation in the model space. The interpretation of the results from the subsequent model depletion studies in terms of the real world then leads to determination of the reservoir qualities required to yield a reasonable chance of water-flood success. The analysis of the study techniques described is accompanied by examples of the specific study methods applied in performing the water-flood feasibility study on some of the pinnacle reef pools in. the northern portion of the Zama Basin in northwestern Alberta. Introduction THE PROBLEM of evaluating the waterflood feasibility of a given pool within a complex reservoir system can be very difficult, particularly in a reef environment with many small pools (which can contain only one or two wells). The purpose of this discussion is to describe the techniques developed in formulating a numerical model, together with the independent analysis of reservoir performance factors to define the correspondence between the model space and the real world, The logical operations leading to conclusions regarding probable waterflood performance of given pools will be amplified by reference to the studies performed by Gulf Canada in the Zama Basin of northwestern Alberta. Underlying Philosophy Development of a mental picture of the reservoir-aquifer system is considered to be the most important aspect of commencing a multi-pool study, along with the assembly of a set of tentative theories regarding the courses and relative effects of fluid movement within and between hydrocarbon-bearing pinnacles. The standardization or "history match" phase of the numerical simulation studies can then be used as a testing ground for these hypotheses, within the framework of the continuity equation, the physical description of the system and the well performance. A sequence of revisions to these theories should then be based on the results of the initial series of model runs. The final goal in the reservoir modelling phase of the study is the development of a set of working hypotheses which agree with all aspects of the observable reservoir data, with as few unexplainable exceptions as possible. The consensus of reservoir engineering opinion is usually the basis for the initial set of theories. The usual assumption in a multi-well reef development is that each reef can be geometrically defined with reasonable accuracy, and the primary concern early in the study is to derive an adequate reservoir description. The assumption is usually made that water or excess gas production early in the life of each reservoir can be attributed to coning, with saturation effects becoming more important later.

Design and analysis of small submersible pressure hulls

Small submersibles, which permit man to observe and work as part of the three-dimensional undersea environment, are among the most promising tools for achieving effective exploitation of the oceans. An important element of any submersible is the pressure hull, frequently contributing one-fourth to one-half and more of the total vehicle weight. The Naval Ship Research and Development Center has played a major role in developing pressure hull structures for undersea vehicles. This paper describes some of the principal structural features of existing and envisioned small submersibles and summarizes recent advances in design and analysis methods. Particular emphasis is given to computer programs developed and/or used at the Center. Specifically, it describes advances in stress, stability, and vibration analyses as well as early stage developments in structural fatigue and reliability analyses. It also discusses computer programs and automated procedures designed for rapid response in feasibility studies and preliminary and final design cycles; these provide for both the generation of input data and the graphical display of computed results.

A mesh generation method based on set theory

A method is proposed to study automatic generation of input data to finite element programs by the computer with minimal human involvement. Based on a set of objective criteria, a consistent procedure is developed to scan through the geometric idealization of a boundary to form regions for mesh generation. This procedure is supported by a rigorously built mathematical model. A cyclic set is defined according to the ordering of segments on a boundary. Corresponding to this is a quadrilateral set whose elements represent the partitioning of the geometry into regions for mesh generation. Theorems are proven establishing the uniqueness and completeness of this procedure. By means of this mathematical model, a computer program is written for automatic mesh generation together with evaluation of results by a given set of objective criteria. Examples are presented with simply connected and with multiply connected geometry.

Natural coordinate systems an automatic input data generation scheme for a finite-element method

A description of a scheme for automatic input data generation for a finite-element method is presented. The basic algorithm is based on a suitable classification of the topological properties of complex geometrical configurations in one-, two-, or three-dimensional space. The algorithm provides for an automatic means of discretization for continuous domains of any form by using the concept of natural coordinate systems; this concept is introduced in this paper. Depending on the complexity of the geometrical form and the diversity of the field quantities associated with different regions in the domain considered or on its boundary, the solution domain is divided into subdomains. Each subdomain has homogeneous field properties and reasonably convex form. The field quantities and geometrical properties associated with each region and the connectivity information of the adjacent subdomains are provided by the user as input. The generation of the mesh, computations of nodal coordinates, and the distribution of the field properties to each finite element are automatically performed. Examples from stress analysis are given.