Microcomputer Simulation Research Articles

A Mathematical Model for Calculating Intestinal Villus Surface Area in Broiler Chickens

Villus surface area (VSA) is measured to reflect the active absorption surface of the intestine under different experimental conditions. In context, it has been recommended to use a suitable model for calculating VSA of different shapes. However, no more attention has been paid to this point. Thus, a mathematical model, to calculate the VSA of ridge-like shape villi, was proposed for increasing the accuracy of VSA measuring. Then, to test the proposed model, a comparison between the common (tube-like) and proposed (ridge-like shape) models was done using real 416 villi morphometrics (height and width) of one-day-old specific pathogen-free broiler chicks. Also, Python program® was used to do a microcomputer simulation for comparing between models. Statistically, the apex surface area of the tube-like shape was greater than that of the ridge-like shape (P<0.0001). While the total VSA of tube-like shape villus was numerically greater than this of ridge-like shape ones. These results were confirmed by the simulation study. In conclusion, since the villus shape affects the VSA, the proposed model can be recommended for calculating the surface area of the ridge-like shape villi instead of the common ones. Besides villus morphometrics, the villus shape-surface area relationship can be used to explain the changes in absorption capacity and related economic parameters such as growth rate and body weight under different experimental conditions.

Recent advances in the development of simulation software

Since the first microcomputer simulation languages became available significant developments have taken place such as major enhancements of existing languages, the availability of animation capabilities, the development of simulation systems specifically designed for microcomputers, domain dependent simulators and powerful user interfaces. This paper will attempt to identify, analyse and discuss these trends in the development of microcomputer simulation software, the associated changes that are taking place in the application of the simulation modelling approach and the relevant implications for the simulation user.

Micro-computer simulation software: A review

Simulation modelling has proved to be one of the most powerful tools available to the Operations Research Analyst. The development of micro-computer technology has reached a state of maturity where the micro-computer can provide the necessary computing power and consequently various powerful and inexpensive simulation languages for micro-computers have became available. This paper will attempt to provide an introduction to the general philosophy and characteristics of some of the available micro-computer simulation languages. The emphasis will be on the characteristics of the specific micro-computer implementation rather than on a comparison of the modelling features of the various languages. Such comparisons may be found elsewhere.

Errors in measuring blood flow velocity behind hepatic mass lesions using color doppler sonography.

The authors designed microcomputer simulation models to investigate the combined effect of a distorted grayscale ultrasound image and an inaccurately measured Doppler angle on the accuracy of measurement of blood-flow velocity in vessels located behind mass lesions in the liver. Error decreased when flow was measured at the midpoint of the posttumoral segment of the vessel and increased with distance between the mass and the vessel, with inclination of the vessel, and with decrease in the diameter of the mass. Error was least with the sector probe, intermediate with the convex probe, and greatest with the linear probe. These findings suggest that the error can be minimized when measuring blood flow velocity in a vessel located behind a mass, if the Doppler images are acquired using a sector probe from the midpoint of the posttumoral segment of the vessel.

Post-tumoral distorted vascular images: Diagnostic problem of sonogram

Most sonographists have probably encountered cases of liver tumor in which vascular images were distorted or poorly defined when the scanning plane included a tumor in front of a vessel. This phenomenon was thought to results from sound refraction through the tumor. We analyzed this phenomenon first by using the results of clinical studies, then by using the results of basic studies with microcomputer simulation models. Results of clinical studies showed (1) a small notch in vessel walls (29/83, 34.9%) and poor definition of vessels (29/83, 34.9%) appearing behind the tumors, as well as (2) poor vessel definition, predominantly behind heterogenous tumors (28/29, 96.6%). Basic studies showed that vessels appearing behind tumors with homogenous internal structure has a smooth rotation, and that these vessels were visualized as combinations of multiple small fragments behind tumors with heterogeneous internal structure. Refraction of the US beam passing through a tumor, especially one with a heterogeneous internal structure, results in distortion of the US image of vessels located behind such tumors. Familiarity with the pattern of artifactually distorted vessel images can help in preventing misinterpretation of these findings as true pathologic vascular changes. This limitation of sonography necessitates the use of other diagnostic modalities for accurate observation of a vessel situated behind a tumor.

Accuracy of liver puncture under US guidance: re-evaluation by microcomputer simulation model.

To evaluate, using microcomputer simulation models, the degree of distortion of the puncture needle in sonograms used during a liver puncture under ultrasound guidance. We made a simplified simulation model of the puncture needle passing through the abdominal wall to the target lesion in the liver (cases without ascites), and additionally through ascites between the abdominal wall and the liver (cases with ascites), to evaluate the degree of distortion of the puncture needle in the sonogram. We considered the thicknesses and sound velocities of the abdominal wall and the ascites fluid, as well as the puncture angle, on the degree of distortion. (1) Cases without ascites: The puncture needle displayed on sonogram shifted predominantly anteriorly with a displacement error between 6 mm forward and 1 mm backward and with an angular error between 2.2 degrees forward and 0.1 degree backward when the abdominal wall was muscular, and the pattern of distortion had an inverted S-shape. It was displayed predominantly posteriorly with a displacement error between 14 mm backward and 2 mm forward and with an angular error between 3.7 degrees backward and 1.2 degrees forward when the abdominal wall was fatty, and the pattern was S-shaped. Regardless of the composition of the abdominal wall, when the abdominal wall was thin, the more obtuse the puncture angle was, the larger the shift was, and when the abdominal wall was thick, the more acute the puncture angle was, the larger the shift was. (2) Cases with ascites: (a) Regardless of the quantity and sound velocity of the ascites, the puncture needle shifted predominantly anteriorly with a displacement error between 7 mm forward and 3 mm backward and with an angular error between 3.1 degrees forward and 1.9 degrees backward when the abdominal wall was muscular, and showed the inverted S-shaped pattern. In contrast, it shifted predominantly posteriorly with a displacement error between 17 mm backward and 5 mm forward and with an angular error between 3.7 degrees backward and 3.9 degrees forward when the abdominal wall was fatty, and showed the S-shaped pattern. (b) Regardless of the sound velocity of the ascites fluid and the composition of the abdominal wall, the shift of the puncture needle changed little with differing amounts of ascites. It is highly recommended that a liver puncture under US guidance be performed taking into account the pattern of distortion of the puncture needle in each situation.

Case Studies of Microcomputer and Interactive Video Simulations in Middle School Earth Science Teaching

This article synthesizes the results of three case studies of middle school classrooms in which computer and video materials were used to teach topics in earth and space science through interactive simulations. Cases were selected to span a range of middle school grade levels (sixth through eighth), teachers' levels of experience (student teacher through 16-year veteran), levels of technology used (Apple II through Macintosh-controlled interactive videodisk), and classroom organization patterns in relation to technological resources (teacher-centered presentations with individual seatwork through small-group exploratory activities in a multiple-computer setting). Specific instances are described illustrating ways in which common current practice is problematic in two broad categories: 1) classroom procedures and task structures established by teachers are often inconsistent with the intentions of software and video designers and producers; and 2) students' actual behavior and descriptions of their learning experiences with computer simulations are often very different from those initially envisioned or even immediately perceived by their teachers. In light of these findings, suggestions are made regarding improved design principles for such materials and how middle school science teachers might better conduct lessons using such simulations, specifically urging a sharper focus on the value of: transparency of the software interface; substantive content learning as well as student enjoyment; hybrid cooperative/competitive classroom task structures; maintaining intrinsic motivation in students; and students' feeling of ownership of problem solutions.

Rotation of the diaphragmatic echo behind the liver tumor. Clinical significance and computer analysis

Objective: We undertook this study to investigate the appearance of the diaphragmatic echo behind liver tumors and to analyze the possible mechanism of this artifact by using a microcomputer simulation model. Subjects and methods: (1) Sonograms of 76 liver tumors in the right intercostal scanning plane were analyzed. These 76 tumors consisted of 22 hepatocellular carcinomas (HCC), 23 liver metastasis and 31 hemangiomas. The appearances of the post-tumoral diaphragmatic echo were evaluated with respect to the remaining diaphragmatic echo. (2) We evaluated how the sound refraction through the liver tumor affects the displayed diaphragmatic echo, by using microcomputer simulation model. Results: (1) A clockwise rotation of the diaphragmatic echo was frequently seen in the metastasis group in comparison with the HCC or hemangioma groups (P < 0.01). (2) A counterclockwise rotation of the diaphragmatic echo was seen mainly in the hemangioma group in comparison with the HCC or metastasis groups (P < 0.01). (3) The difference in acoustic velocity between the tumor and the surrounding tissue did not cause parallel displacement of the diaphragmatic echo but rather a rotation. (4) Computer simulation analysis showed that in the case of a tumor with acoustic velocity greater than that of the surrounding tissue, the diaphragmatic echo showed a clockwise rotation. (5) It showed also that in the case of a tumor with acoustic velocity less than that of the surrounding tissue, the diaphragmatic echo displayed a counterclockwise rotation. Conclusion: The appearance of the diaphragmatic echo changed according to the nature of the liver tumor. Knowledge of this artifact can improve the sonographic diagnosis of liver tumors.

Rotation of the diaphragmatic echo behind the liver tumor. Clinical significance and computer analysis

Objective: We undertook this study to investigate the appearance of the diaphragmatic echo behind liver tumors and to analyze the possible mechanism of this artifact by using a microcomputer simulation model. Subjects and methods: (1) Sonograms of 76 liver tumors in the right intercostal scanning plane were analyzed. These 76 tumors consisted of 22 hepatocellular carcinomas (HCC), 23 liver metastasis and 31 hemangiomas. The appearances of the post-tumoral diaphragmatic echo were evaluated with respect to the remaining diaphragmatic echo. (2) We evaluated how the sound refraction through the liver tumor affects the displayed diaphragmatic echo, by using microcomputer simulation model. Results: (1) A clockwise rotation of the diaphragmatic echo was frequently seen in the metastasis group in comparison with the HCC or hemangioma groups ( P < 0.01). (2) A counterclockwise rotation of the diaphragmatic echo was seen mainly in the hemangioma group in comparison with the HCC or metastasis groups ( P < 0.01). (3) The difference in acoustic velocity between the tumor and the surrounding tissue did not cause parallel displacement of the diaphragmatic echo but rather a rotation. (4) Computer simulation analysis showed that in the case of a tumor with acoustic velocity greater than that of the surrounding tissue, the diaphragmatic echo showed a clockwise rotation. (5) It showed also that in the case of a tumor with acoustic velocity less than that of the surrounding tissue, the diaphragmatic echo displayed a counterclockwise rotation. Conclusion: The appearance of the diaphragmatic echo changed according to the nature of the liver tumor. Knowledge of this artifact can improve the sonographic diagnosis of liver tumors.

Diagnosing and altering three aristotelian alternative conceptions in dynamics: Microcomputer simulations of scientific models

AbstractThis is a report on the investigation of a microcomputer‐based system for the diagnosis and remediation of three Aristotelian alternative conceptions of force and motion held by eighth‐grade physical science students. Diagnosis and posttesting were done with computer‐displayed, graphics‐based, multiple‐choice questions. The two remediation simulations were designed to present scientific idealizations and to be perceived by the student as anomalous to the three alternative conceptions. Structured interviews were employed at several points during the study to obtain indications of the conceptions of force and motion of students with different achievement rankings, as well as to determine the students' reactions to the computer pretest questions or the simulations. A student's possession of alternative conceptions was unrelated to whether the student was a strong or weak learner of science. Students who were currently studying dynamics in their classes exhibited a very different pattern of nonscientific answers on the computer diagnostic test than did students who had completed that topic. The completed students who were selected for possession of alternative conceptions were facilitated by the computer simulations in altering their naive conceptions to a significant degree.

Human Factors Studies to Investigate Driver Behavior under In-Vehicle Information Systems: An Interactive Microcomputer Simulation Approach

In-vehicle traveler information systems are being designed to provide drivers with real-time route guidance and/or traffic advisory information. It is expected that these Advanced Traveler Information Systems (ATIS) technologies will have a major impact on travel efficiency by assisting drivers to make better real-time route choices in response to changing network conditions. There is not yet full knowledge as to the impacts that route guidance and traffic advisory systems will have on driver behavior. This paper presents preliminary results from a human factors experiment to investigate the effects of traffic advisory and route guidance information on enroute behavior and travel performance. An interactive microcomputer simulation was used for data collection. The study suggests that both drivers' route choice efficiency and understanding of network conditions can be improved with access to real-time traffic advisory and route guidance information.

In-laboratory experiments to investigate driver behavior under advanced traveler information systems

In-laboratory experimentation with interactive microcomputer simulation is a useful tool for studying the dynamics of driver behavior in response to advance traveler information systems. Limited real-world implementation of these information systems has made it difficult to observe and study how drivers seek, acquire, process, and respond to real-time information. This paper describes the design and preliminary testing of an interactive microcomputer-based animated simulator, developed at the University of California, Irvine, to model pre-trip and enroute driver travel choices in the presence of advanced traveler information systems. The advantages of this simulator are realized in its versatility to model driver decision processing while presenting a realistic representation of the travel choice domain. Results from a case study revealed that increased driver familiarity with travel conditions and network layout reduced driver reliance on information systems and influences diversion behavior.

Computer, Video, and Rapid-Cycling Plant Projects in an Undergraduate Plant Breeding Course

Computer, Video, and Rapid-Cycling Plant Projects in an Undergraduate Plant Breeding Course

Reconstructing Keynesian Economics with Imperfect Competition: A Desk-top Simulation.

The main arguments of this book are almost certain to create controversy and lead to a fundamental reassessment of Keynesian economics. Building on his previous work on modern capitalism, Robin Marris has made theoretical advance which should have a major impact on the economics profession. The book has four main aims. The first is a piece of intellectual surgery - to replace an Achilles heel in the Keynesian theory of aggregate demand and in so doing help to reduce confusion concerning the relation in Keynesian economics between employment and the real wage. The second is to support the revised theory with an economic model based on a rich, user- friendly microcomputer simulation which is included free with the book. The third is to apply the model to the macroeconomic problems of the industrialized market economies in the 1970s, 80s and beyond. And, finally, Robin Marris embellishes the narrative with a personal view of the relationships between Cambridge economists which sheds new light on the intellectual history of the Keynesian revolution.

Microcomputer simulation improves production scheduling for microelectronics manufacturers

Microcomputer simulation improves production scheduling for microelectronics manufacturers

Effectiveness of microcomputer simulations in stimulating environmental problem solving by community college students

AbstractThis study examined the impact of microcomputer simulations on environmental problem solving by community college students. A subordinate question was also addressed: Was the test instrument, which was used to assess the outcome of the treatment, biased by reading ability? The quasiexperimental design used two intact groups of community college students and parallels an earlier study by Rivers and Vockell (1987). The experimental group was assigned three simulation modules that focused on lake pollution analysis, wastewater quality management, and population dynamics. The comparison group was not exposed to any simulations, and served as a quasicontrol to identify possible Hawthorne effects. Effectiveness was assessed by the Test of Integrated Process Skills (TIPS I and II). Statistical analyses were done with t tests, Pearson product‐moment correlation coefficients, and reliability coefficients. The experimental group showed a highly significant improvement in problem‐solving skills after treatment, t(33) = 4.42, p &lt; 0.001. Subtest mean gain scores supported the hierarchical relationships among cognitive modes for transitional operational reasoners as reported by Yap and Yeany (1988). An analysis of the correlation between the TIPS I and Nelson‐Denny reading test scores indicated that the TIPS did not have a reading‐level bias for the subjects in this study. Informal and anecdotal observations described improvements in other problem‐solving skills which were not measured by the TIPS.

A Tool for the Design and Evaluation of Alternative Quality-Control Procedures

I have developed an interactive microcomputer simulation program for the design, comparison, and evaluation of alternative quality-control (QC) procedures. The program estimates the probabilities for rejection under different conditions of random and systematic error when these procedures are used and plots their power function graphs. It also estimates the probabilities for detection of critical errors, the defect rate, and the test yield. To allow a flexible definition of the QC procedures, it includes an interpreter. Various characteristics of the analytical process and the QC procedure can be user-defined. The program extends the concepts of the probability for error detection and of the power function to describe the results of the introduction of error between runs and within a run. The usefulness of this approach is illustrated with some examples.

Oregon's Sanction Units Exchange System for Felony Sentencing Guidelines

Oregon has had a long-standing commitment to use of local sanctions. Minnesota was first state, in 1973, to enact a Community Corrections Act and shift funding and responsibility for sanctioning of some felons from state to counties. Oregon adopted a community corrections act four years later, in 1977. Minnesota and Washington were pioneers in use of state prison capacity calculations in construct ing guidelines.1 The legislation directing develop ment of Oregon's felony sentencing guidelines in 1987 was unique in calling for a structure sensitive not just to amount of state prison space available, but also to the effective capacity of . . . local correc tions facilities and other sentencing sanctions available. As informal advisors to Oregon process, guideline commission staffs in Minnesota and Washington were generous with their sugges tions. A structured sentencing microcomputer simulation model, developed jointly by states of Oregon, Louisiana, and Tennessee and District of Columbia under Bureau of Justice Assistance's 1987-89 Structured Sentencing Program, enabled Oregon Criminal Justice Council to model effects of probationary sentences and alternative sanctions on local caseloads and programs. The Association of Oregon Counties, a powerful state legislative force, supported effort. The Association was sensitive to potential guidelines pressures on county-funded jails and corrections programs. In 1987, when Oregon began to develop its felony sentencing guidelines, 18 of its 33 county jails were under federal court orders related to population. Also, more than 80% of Oregon felons receive non-prison sentences. Developing an elaborate guidelines system to deal with only 20% of offenders who were prison-bound seemed, to Criminal Justice Council, to be addressing only a small part of problem, as well as only a portion of issues related to structured sentencing.2

Model to facilitate studying oxygen and carbon dioxide transport.

A simple model has been constructed for microcomputer (PC) simulations involving basic cardiopulmonary principles of oxygen transport. Students can change parameters such as metabolic rate, blood hemoglobin concentration, barometric pressure, air composition, etc., and study parameter effects on blood gas concentrations and partial pressures. An important feature of the model program is that there are no negative feedback controls to maintain homeostasis. However, after a perturbation has been introduced, adjustments can be made to appropriate variables to correct for abnormal effects. For example, ventilation rate and blood hemoglobin concentration might be adjusted to compensate for low atmospheric oxygen. Because these do not change automatically in the model program, learning is enhanced when the student has to make the appropriate adjustments needed to correct disturbances in the blood gases that follow a perturbation.

Microcomputer Simulation for Teaching Operations Management

Present and potential uses of microcomputers in teaching operations and production management are examined. Microcomputers are generally available to most students and managers. Difficulties lie in developing the most effective learning methods using microcomputers instead of expecting students to self‐learn entirely by working their way through a program manual in front of a screen. Potential uses of microcomputer‐based simulations and the possible learning benefits are explored. Uses of an aggregate planning case study are given as an example, involving manual calculations, group discussion and a microcomputer spreadsheet. The example shows how small groups can learn more effectively about the power and speed of microcomputers by using them in a real situation. The simulation emphasises the useful role of micro‐computers as an integral part of operations planning systems and decision‐making processes.