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Articles 178891 - 178920 of 197988

Full-Text Articles in Engineering

The Influence Of Cross-Cultural Differences On The Interpretation And Understanding Of Aircraft Passenger Safety Briefing Cards, Florian G. Jentsch Mar 1992

The Influence Of Cross-Cultural Differences On The Interpretation And Understanding Of Aircraft Passenger Safety Briefing Cards, Florian G. Jentsch

Master's Theses - Daytona Beach

Aircraft passenger safety briefing cards are an important part of passenger safety education aboard commercial aircraft. The cards must be understood by all readers, regardless of age, gender, or culture. Related research indicates that passengers from different cultures might misunderstand the highly specialized instructions on safety cards.

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Bs News Mar 1992

Bs News

Building Services Engineering

No abstract provided.

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Achieving A Given Reflectance For Unpolarized Light By Controlling The Incidence Angle And The Thickness Of A Transparent Thin Film On An Absorbing Substrate: Application To Energy Equipartition In The Four-Detector Photopolarimeter, R. M.A. Azzam, Kurt A. Giardina Mar 1992

Achieving A Given Reflectance For Unpolarized Light By Controlling The Incidence Angle And The Thickness Of A Transparent Thin Film On An Absorbing Substrate: Application To Energy Equipartition In The Four-Detector Photopolarimeter, R. M.A. Azzam, Kurt A. Giardina

Electrical Engineering Faculty Publications

At a given wavelength λ we determine all possible solution pairs (ϕ, ζ) of the incidence angle ϕ and the thickness ζ of a transparent thin film on an absorbing substrate that achieve a given unpolarized light reflectance Ru. The trajectory of the point that represents a solution pair in the ζ, ϕ plane depends on the optical properties of the film and substrate and on whether Ru is greater than or less than the normal-incidence reflectance -R0 of the bare substrate. When Ru > - R0, the specified reflectance is achieved over a …

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Implementation And Analysis Of Np-Complete Algorithms On A Distributed Memory Computer, Joel S. Garmon Mar 1992

Implementation And Analysis Of Np-Complete Algorithms On A Distributed Memory Computer, Joel S. Garmon

Theses and Dissertations

The purpose of this research is to explore methods used to parallelize NP-complete problems and the degree of improvement that can be realized using different methods of load balancing. A serial and four parallel A* branch and bound algorithms were implemented and executed on an Intel iPSC/2 hypercube computer. One parallel algorithm used a global, or centralized, list to store unfinished work and the other three parallel algorithms used a distributed list to store unfinished work locally on each processor. the three distributed list algorithms are: without load balancing, with load balancing, and with load balancing and work distribution. The …

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Design And Analysis Of Electrical Circuits That Produce Fractional-Order Differentiation, Richard N. Hughes Mar 1992

Design And Analysis Of Electrical Circuits That Produce Fractional-Order Differentiation, Richard N. Hughes

Theses and Dissertations

Two half-order differentiator circuit designs were investigated and their electrical performance evaluated (Oldham and Oldfield). Initially, each circuit design was computer modelled and simulated using the HSPICE computer analysis program. Then, each circuit design (Oldham and Oldfield) was fabricated with two different component technologies. This resulted in four circuits, realized on printed circuit boards, to be evaluated--Oldham discrete component; Oldham hybrid component; Oldfield discrete component; and Oldfield surface mount component. The characterizations of each circuit's electrical performance is documented with time, phase, gain, noise and spectrum responses. A comparison of each circuit's performance versus the design criteria and computer model …

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Feasibility Of An Antiproton Catalyzed Fission Fragment Rocket, David S. Hidinger Mar 1992

Feasibility Of An Antiproton Catalyzed Fission Fragment Rocket, David S. Hidinger

Theses and Dissertations

The purpose of this project was to investigate the feasibility of an antiproton catalyzed fission fragment rocket (FFR). The FFR is characterized by the extraction of fission fragments from the fuel, and the utilization of their kinetic energy for thrust generation. A significant drawback to previous FFR designs was the required critical nuclear pile as the fission fragment source. The author examined the possibility of replacing the critical pile with a sub- critical pile driven by antiprotons. Recent experiments have revealed that antiprotons stimulate highly energetic fissions in 238U, with a neutron multiplicity of 13.7 neutrons per fissions. This interaction …

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Development Of A System For Survey Of Radon Concentration Of The Dayton Area Using A Liquid Scintillation Counter And Analysis Of The Data, Taewon Kim Mar 1992

Development Of A System For Survey Of Radon Concentration Of The Dayton Area Using A Liquid Scintillation Counter And Analysis Of The Data, Taewon Kim

Theses and Dissertations

A system to do a large scale survey was developed. The data obtained from the survey was analyzed using a database. The database incorporated an equation for converting cpm into radon concentration pCi/ℓ). The equation of conversion, protocol for measuring radon concentration, survey form, and a database program were modified (from previous theses) or developed for this thesis. The elution time constant, adsorption time constant, and calibration factor were calculated for equation of conversion. Two surveys were during the course of the thesis. On the first survey, the arithmetic average radon concentration with standard error of the mean was 2.9 …

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Gamma-Ray Effects Testing In Lawrence Livermore National Laboratory's Nova Upgrade Facility, David H. Marchant Mar 1992

Gamma-Ray Effects Testing In Lawrence Livermore National Laboratory's Nova Upgrade Facility, David H. Marchant

Theses and Dissertations

Gamma ray effects testing in Lawrence Livermore National Laboratory's (LLNL) planned Nova Upgrade facility is examined. Emphasis is placed on converting neutron energy from inertial confinement fusion in to gamma rays while shielding the test objects from neutrons and debris. Although predicted gamma doses in the Nova Upgrade facility are an order of magnitude less than those produced in some current facilities, dose uniformity, the ratio of minimum to maximum gamma dose is predicted to be greater than 0.75 across a larger, 13, 000 cm2, test bed. Peak gamma dose rates are predicted to be on the order …

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Exponential Characteristic Spatial Quadrature For Discrete Ordinates Neutral Particle Transport In Slab Geometry, Glenn E. Sjoden Mar 1992

Exponential Characteristic Spatial Quadrature For Discrete Ordinates Neutral Particle Transport In Slab Geometry, Glenn E. Sjoden

Theses and Dissertations

A new discrete ordinates spatial quadrature scheme is presented for solving neutral particle transport problems. This new scheme, called the exponential characteristic method, is developed here in slab geometry with isotropic scattering. This method uses a characteristic integration of the Boltzmann transport equation with an exponential function as the assumed from of the source distribution, continuous across each spatial cell. The exponential source function is constructed to globally conserve zeroth and first spatial source moments and is non-negative. Characteristic integration ensures non- negative fluxes and flux moments. Numerical testing indicates that convergence of the exponential characteristic scheme is fourth order …

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Model Of A Nuclear Thermal Test Pipe Using Athena, Mark J. Dibben Mar 1992

Model Of A Nuclear Thermal Test Pipe Using Athena, Mark J. Dibben

Theses and Dissertations

Nuclear thermal propulsion offers significant improvements in rocket engine specific impulse over rockets employing chemical propulsion. The computer code ATHENA (Advanced Thermal Hydraulic Energy Network Analyzer) was used in a parametric analysis of fuelpipe. The fuelpipe is an annular particle bed fuel element of the reactor with radially inward flow of hydrogen through it. The outlet temperature of the hydrogen is parametrically related to key effects, including the effect of reactor power at two different pressure drops, the effect of the power coupling factor of the Annular Core Research Reactor, and the effect of hydrogen flow. Results show that the …

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An Examination Of The Feasibility Of A Nuclear-Pumped Laser-Driven Inertial Confinement Fusion Reactor With Magnetically Protected Walls, John M. Jacobson Mar 1992

An Examination Of The Feasibility Of A Nuclear-Pumped Laser-Driven Inertial Confinement Fusion Reactor With Magnetically Protected Walls, John M. Jacobson

Theses and Dissertations

A preliminary design study of a nuclear-pumped laser-driven inertial confinement fusion reactor with a magnetically protected first wall using an advanced DT-ignited, DD-fueled pellet demonstrated the feasibility of such a concept. This paper presents a parametric study of the required energy multiplication in the blanket, the pellet injection rate, and the net efficiency of this is conceptual reactor for advanced pellet yields. A model of the reactor energy balance yields a required energy multiplication of 2.4. A cylindrical design for a helium-cooled blanket demonstrates that natural uranium micropellets in a laser pump region provide a multiplication of 2.9 with a …

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Design Of A Warm X-Ray Radiation Environment For Nuclear Weapons Effects Testing In The Nova-Upgrade Facility, Jeffrey E. Malapit Mar 1992

Design Of A Warm X-Ray Radiation Environment For Nuclear Weapons Effects Testing In The Nova-Upgrade Facility, Jeffrey E. Malapit

Theses and Dissertations

This engineering design project examined the creation of a radiation environment for warm x-ray effects testing in the Nova Upgrade laser facility. With the use of the MORSE Monte Carlo Code and the DABL69 Broad-group cross section library, the ignition of an inertial confinement fusion pellet using D-T fuel in a test cassette was modeled in the Nova Upgrade's target chamber. Various x-ray scattering materials were used in the test cassette to include enriched lithium hydride, polyethylene, liquid hydrogen, liquid helium, and liquid methane. The lithium hydride produced the best warm x-ray doses and least neutron dose. The predicted x-ray …

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Design And Construction Of A Channel Electron Multiplier Based Mossbauer Spectroscopy System, Daniel J. Robbins Mar 1992

Design And Construction Of A Channel Electron Multiplier Based Mossbauer Spectroscopy System, Daniel J. Robbins

Theses and Dissertations

A channel electron multiplier (cem) detector system was designed and built to provide a signal to a Mossbauer spectroscopy system in an effort to obtain a better signal-to-noise ratio than achievable with a proportional counter system. Three cems are contained in a vacuum chamber built using standard components. Gamma, rays of 14.4-keV energy from a 57Co source enter from outside the chamber through a window and are absorbed by an 57Fe target near the cems. The target emits internal conversion electrons which are collected by the cems and a Mossbauer spectrometer collects the signal. The system produces a …

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Multilayer Perceptrons For Classification, Lisa M. Belue Mar 1992

Multilayer Perceptrons For Classification, Lisa M. Belue

Theses and Dissertations

Techniques for training, testing, and validating multilayer perceptrons are thoroughly examined. Results obtained using perceptrons are compared and contrasted with two multivariate discriminant analysis techniques- logistic regression and k neighbor. Methods for determining significant input features are investigated and a procedure for examining the confidence to place in the significance of these features is developed. Procedures to evaluate the applicability of high-order feature inputs are examined. These methods and procedures are applied to two very different applications. The first application concerns the prediction of Air Force pilot retention/separation rates for input to force projection models. The second application concerns the …

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An Analysis Of The Endurance Of Mobile Satellite Command And Control Systems, Steven O. Brown Mar 1992

An Analysis Of The Endurance Of Mobile Satellite Command And Control Systems, Steven O. Brown

Theses and Dissertations

This study investigated the endurance of a single deployed generic mobile space (GMS) command and control (C2) system. Specifically, factors which affect overall system performance were examined. The analysis began with the development of a simulation model for a GMS C2 system. Optimal settings of factor levels were determined by using the model to find peak system endurance and availability. Factors set were field support vehicle (FSV) access, numbers of maintenance personnel, and numbers of spare components available. After optimum values were chosen for these factors, an experimental design was conducted to determine factor effect between maintenance manpower and the …

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Transformation Of Combat Data In Support Of Battle Trace, Hyoung-Kyu Choi Mar 1992

Transformation Of Combat Data In Support Of Battle Trace, Hyoung-Kyu Choi

Theses and Dissertations

The purpose of this study was to find an appropriate way of characterizing battle data as a function of time. This study was initially designed to remove the numerical instability problem cited in Barr's battle trace methodology as suggested by TRAC-MTRY. The research focused on the instability problem and identifying/recommending a technique that improved the efficiency of computation, and enhanced an analyst's ability to meaningfully interpret the battle trace. Two Lanchester's Square Law based methodologies are introduced and analyzed. The results of this analysis indicate that the battle trace of a constant value generated by Lanchester's Square Law integration seemed …

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Visual Information Processing And Response Time In Traffic-Signal Cognition, Hasan H. Demirarslan Mar 1992

Visual Information Processing And Response Time In Traffic-Signal Cognition, Hasan H. Demirarslan

Theses and Dissertations

In man-machine design, it is important to quantify the reaction time components instead of simply determining the lump-sum reaction time to stimulus. The primary purpose of this thesis was to investigate the reaction time components, such as visual perception and muscle response time, and to quantify them by separating from their aggregated sum. The prime example, traffic-signal cognition simulation was used to examine human reaction time to signal change. With a modified computer program that stimulates the driver's approach to the intersection, we measured the subject's reaction times and examined behavioral patterns. Twelve subjects were involved in the experiment. A …

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An Investigation Of Modifications To The Tac Campaign Model, Efgan Denguer Mar 1992

An Investigation Of Modifications To The Tac Campaign Model, Efgan Denguer

Theses and Dissertations

This research investigates the cost and budget modifications to Mixmaster which is an aggregate version of the Theater Attack Model (TAM). Seven simple cost employment methods, a goal programming approach, a probabilistic approach for determining cost coefficients, and goal programming version of that probabilistic approach were applied to Mixmaster. Also, Mixmaster was enhanced with an additional leading constraint to incorporate the Air Force tactical considerations in a campaign scenario. The results favor the advantages of the goal programming approaches. In addition, the probabilistic approach introducing the time factor in the computations promises more accurate results, given that the required parameters …

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Automating The Weekly Flight Scheduling Process At The Usaf Test Pilot School, Gary G. Foster Mar 1992

Automating The Weekly Flight Scheduling Process At The Usaf Test Pilot School, Gary G. Foster

Theses and Dissertations

This study investigated different scheduling solution approaches that could be automated and applied at the USAF Test Pilot School (TPS). Currently at the TPS, flight schedules are manually developed on a daily basis. Weekly flight schedules are not developed due to the large quantity of data that must be processed to develop a flight schedule for an entire week. A weekly flight scheduling approach would reduce the occurrence of scheduling problems and unbalanced resource utilization, both of which are often the result of a daily flight scheduling approach. In addition, posting a flight schedule for the entire week would improve …

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Modular Simulation Of Hei Fragments And Blast Pressure, Gordon L. Galloway Mar 1992

Modular Simulation Of Hei Fragments And Blast Pressure, Gordon L. Galloway

Theses and Dissertations

The fragmentation and blast pressure of High Explosive Incendiary projectiles are major causes of aircraft fuel fires. Because Halon 1301 is being banned from DoD use as a fire suppressant, alternative fire suppressants must be developed and tested. These new suppressants must counteract the fire directly or eliminate one or more of the factors which cause the fire. To this end, this thesis takes a detailed look at the HEI processes that lead to a fire. A comprehensive review of the current knowledge and understanding of these processes is presented. In addition, hypothesized dependencies between the various processes are stated. …

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Causal Univariate Spatial-Temporal Autoregressive Moving Averages (Starma) Modelling Of Target Information To Generate Tasking Of A World-Wide Sensor System, Kelly A. Greene Mar 1992

Causal Univariate Spatial-Temporal Autoregressive Moving Averages (Starma) Modelling Of Target Information To Generate Tasking Of A World-Wide Sensor System, Kelly A. Greene

Theses and Dissertations

The Department of Defense employs a resource limited world-wide sensor system to detect certain events of interest. The purpose of this research was to establish a methodology using a univariate causal STARMA model for forecasting the relative probability of an event occurring in a geographical location during a time block of the day. These relative probabilities are used as input for a tasking model that assigns the scarce sensor resources so as to optimize the detection of these events. The STARMA model is appropriate for forecasting the relative probabilities because a definite temporal relationship and a definite spatial relationship exists …

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Developing Cmmca Flight Profiles For Cruise Missile Tracking, Andrew C. Hachman Mar 1992

Developing Cmmca Flight Profiles For Cruise Missile Tracking, Andrew C. Hachman

Theses and Dissertations

The Air Force has recently acquired two aircraft dedicated for cruise missile tracking. These aircraft, known as the Cruise Missile Mission Control Aircraft (CMMCA), are responsible for collecting data from the missile and United States. Due to tracking and positively controlling the missile during live fire testing over the western the limited tracking radar range and the flight characteristics of the CMMCA, tracking cruise missiles through complex maneuvers is not always possible. A FORTRAN optimization, based on flight simulation and optimal control theory, was written in a prior thesis effort in order to determine optimal CMMCA flight profiles for tracking …

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Optimization Of Stochastic Response Surfaces Subject To Constraints With Linear Programming, Robert G. Harvey Mar 1992

Optimization Of Stochastic Response Surfaces Subject To Constraints With Linear Programming, Robert G. Harvey

Theses and Dissertations

This research investigated an alternative to the traditional approaches of optimizing a stochastic response surface subject to constraints. This research investigated the bias in the expected value of the solution, possible alternative decision variable settings, and a method to improve the solution. A three step process is presented to evaluate stochastic response surfaces subject to constraints. Step 1 is to use a traditional approach to estimate the response surface and a covariance matrix through regression. Step 2 samples the objective function of the linear program (i.e., response surface) and identifies the extreme points visited. Step 3 presents a method to …

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Confidence Interval Estimation For Output Of Discrete-Event Simulations Using The Kalman Filter, Randall B. Howard Mar 1992

Confidence Interval Estimation For Output Of Discrete-Event Simulations Using The Kalman Filter, Randall B. Howard

Theses and Dissertations

Discrete-event simulation is computer modeling of stochastic, dynamic systems. The Kalman filter is a Bayesian stochastic estimation algorithm. Because of the correlated nature of simulation output, it is difficult to apply the methods of classical statistics directly when constructing confidence intervals of discrete-event simulation parameters. Through the determination of a dynamics equation and application of the Kalman filter to simulation output data, three new confidence interval construction techniques have been developed. One technique obtains an estimate of the mean value and its associated variance from an estimated Kalman filter. The second technique utilizes Multiple Model Adaptive Estimation (MMAE) techniques to …

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An Analysis Of Escort Formations, Mustafa Ilhan Mar 1992

An Analysis Of Escort Formations, Mustafa Ilhan

Theses and Dissertations

This study used computer simulation to investigate escort fighter formations unknown interceptor threat environment. A USAF computer simulation model, TAC, was used to simulate air combat between the escorts and the interceptors in several different combat scenarios. The escort formations were defined by the vertical and horizontal distances of the escort fighters from the main strike body. Interceptors were characterized as one of two types of fighters with dissimilar aircraft frames and missile firing ranges. A central composite design was used to mathematically model the effect of escort formations and interceptor type on the survivability of the bombers and escorts. …

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Effects Of Facility Configurations And Scheduling Techniques On Aircraft Throughput For Warner Robins Alc Paint/Depaint Facilities, David V. Mcelveen Mar 1992

Effects Of Facility Configurations And Scheduling Techniques On Aircraft Throughput For Warner Robins Alc Paint/Depaint Facilities, David V. Mcelveen

Theses and Dissertations

The purpose of this research was to determine the effects of configuration options and dispatching rules on aircraft throughput for the WR- ALC paint/depaint facilities. A simulation model was constructed and used for this analysis as the primary means to conduct the research. The dispatching rules considered were first come first served, largest number in queue, shortest processing time, and a look ahead heuristic. Due to a reduction in the number of paint aircraft, no configuration option differing from the baseline significantly affected aircraft throughput. Dispatching rules were also found to produce no significant differences on aircraft throughput. Configuration options …

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An Outline For A Manufacturing Planning And Control System For A Repair/ Overhaul/Rebuilding Environment, Peter H. Miyares Mar 1992

An Outline For A Manufacturing Planning And Control System For A Repair/ Overhaul/Rebuilding Environment, Peter H. Miyares

Theses and Dissertations

This study outlines a structure for a manufacturing planning and control (MPC) system for a repair/overhaul/rebuilding environment. Included an examination of the organizational components that must be incorporated into the system and the planning functions for which the system can be used. The study compares and contrasts the differences between an MPC system for a maintenance organization and a manufacturing organization and concludes that the MPC system for a maintenance organization must account for the greater degree of variability that occurs within the process. The proposed system is composed of an information system which collects data from throughout an organization …

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Quantifying The Impact Of The Acquisition Professional Development Program Certification Requirements On The Air Force Institute Of Technology, Paul A. Nicholson Mar 1992

Quantifying The Impact Of The Acquisition Professional Development Program Certification Requirements On The Air Force Institute Of Technology, Paul A. Nicholson

Theses and Dissertations

The purpose of this research is to determine the impact of implementing the Acquisition Professional Development Program on the Air Force Institute of Technology. APDP is part of a DOD-wide effort to decrease inefficiency in the procurement process. The program encompasses a tri-level certification process based on experience, training, and educational standards. APDP serves as a guideline for professional development of acquisition personnel from entry to senior level management. Many of the courses required for certification are offered through AFIT School of Systems and Logistics. Integrating the new educational requirements as a standard for career development is expected to produce …

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A Sensitivity Analysis Of Circular Error Probable Approximation Techniques, Peter Puhek Mar 1992

A Sensitivity Analysis Of Circular Error Probable Approximation Techniques, Peter Puhek

Theses and Dissertations

Several algebraic CEP estimates models were examined in this study. Each assumes that the crossrange and downrange miss distances of the sample data follow a bivariate normal distribution. The analysis determined the sensitivities of these models to changes in the parameters of sample size, bias, correlation, and ellipticity. The accuracy of each model is expressed in terms of relative error, and the parameter regions in which a certain method dominated as the most accurate were noted. In general, it was found that bias was the most significant parameter in determining the best CEP method. A simple method, based on the …

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Spartan: An Instructional High Resolution Land Combat Model, David K. Cox Mar 1992

Spartan: An Instructional High Resolution Land Combat Model, David K. Cox

Theses and Dissertations

This project developed an instructional high resolution land combat simulation model. The purpose of this model is to demonstrate common techniques of modeling used in the present generation of US Army land combat models. This model is stochastic and uses an event scheduling type of discrete event time algorithm. The model represents a maximum of two six-man infantry squads in direct fire combat. The individual soldiers move, search for targets, engage targets, and react to hostile encounters. The data values provided will the model are all. generic and hypothetical. The model is only intended as a demonstration tool and has …

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