Showing papers on "Design tool published in 1972"

Ergonomics in design using a computer man and conversational graphics

Abstract: A throe dimensional variable dimensioned computer model of a man has been developed which can be used as a conversational mode design tool. This paper illustrates the use of this model for equipment design, in particular to determine whether controls can be reached and whether equipment dimensions are suitable to match different members of the population. The equipment may be described cither by special purpose or general purpose environmental modelling systems. The modules of the general purpose system may be assembled into a model of the equipment and then evaluated by taking the operator, represented by the computer man, through a typical work sequence. If the dimensions or positions of the modules are unsatisfactory they may be altered conversationally and the new design retested.

Failure mode analysis to predict product reliability.

Abstract: The failure mode analysis (FMA) is described as a design tool to predict and improve product reliability. The objectives of the failure mode analysis are presented as they influence component design, configuration selection, the product test program, the quality assurance plan, and engineering analysis priorities. The detailed mechanics of performing a failure mode analysis are discussed, including one suggested format. Some practical difficulties of implementation are indicated, drawn from experience with preparing FMAs on the nuclear rocket engine program.

Computation of stresses and strains for the design of flexible pavements

Abstract: THE DEVELOPMENT OF IMPROVED DESIGN METHODS FOR FLEXIBLE PAVEMENTS REQUIRES AN ANALYTIC TOOL THAT IS RELATIVELY SIMPLE AND CHEAP FOR USE IN ROUTINE DESIGN. CURRENTLY LINEAR-ELASTIC THEORY IS CONSIDERED THE MOST SATISFACTORY FOR THIS PURPOSE, BUT THE VARIOUS SOLUTIONS AVAILABLE ARE THEMESELVES RATHER INCONVENIENT TO USE. TABULATED RESULTS FOR THREE-LAYER SYSTEMS REQUIRE A LENGTHY INTERPOLATION PROCEDURE TO OBTAIN RESULTS FOR VARIABLES OTHER THAN THOSE TABULATED. ON THE OTHER HAND, THE POWERFUL AND FLEXIBLE MULTILAYER COMPUTER PROGRAMS REQUIRE A LARGE, FAST COMPUTER AND CAN THUS BE EXPENSIVE TO RUN. A COMPUTER PROGRAM CALLED "INTERPOLATION" HAS BEEN DEVELOPED TO CARRY OUT INTERPOLATION CALCULATIONS ON THE THREE-LAYER ELASTIC LAYERED SYSTEM RESULTS TABULATED BY JONES IN 1962. THE OBJECT OF THIS PROGRAM IS TO PROVIDE A PAVEMENT DESIGN TOOL, CONSIDERED TO BE MORE CONVENIENT THAN EITHER THE TABLES THEMSELVES OR THE COMPLEX MULTILAYER COMPUTER PROGRAMS NOW AVAILABLE. THE INTERPOLATION PROCEDURE IS BASED ON FITTING A CURVE TO THE LOG-LOG PLOT OF STRESS FUNCTION AGAINST EACH OF THE DEPENDENT VARIABLES USED BY JONES, WHICH SPECIFY THE SYSTEM. THE RESULTS HAVE THE SAME RESTRICTIONS AS JONES' TABLES, NAMELY THAT ALL LAYERS HAVE A VALUE OF 0.5 FOR POISSON'S RATIO, AND RESULTS ARE PRODUCED ON THE CENTERLINE OF A SINGLE WHEEL LOAD AT THE TWO INTERFACES. FROM A DESIGN POINT OF VIEW, THIS LATTER RESTRICTION IS NOT LIKELY TO BE IMPORTANT. THE "BISTRO" MULTILAYER COMMPUTER PROGRAM WAS USED TO CHECK THE ACCURACY OF RESULTS, AND THIS APPERAS SATISFACTORY FOR DESIGN PURPOSES. THE INTERPOLATION PROGRAM HAS BEEN INCORPORATED IN A SIMPLIFIED PAVEMENT DESIGN PROGRAM IN WHICH AN APPROXIMATE NONLINEAR ANALYSIS MAY BE USED IF REQUIRED.

An approach to the total design of instructional systems by simulation

Abstract: The problem of designing integrated hardware, software, and application systems using simulation as the main design tool is investigated. A proposed design methodology incorporating an iterative loop is then employed to the design of a system for Computer Assisted Instruction. Models of the hardware, the operating system, and the application system are developed, integrated, and simulated to generate a hardware configuration for a 20-terminal system. The performance of this system under operating conditions is then monitored while varying the number of active terminals, the load (requests from terminals), the student think time, and the system overhead. Analysis of the performance measures shows that the student think time is a dominant parameter as it effectively determines the system workload due to the small capacity of the system modeled.