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1993

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Articles 1231 - 1260 of 1343

Full-Text Articles in Engineering

An Optimal Nonblocking Multicast Virtual Circuit Switch, Jonathan S. Turner Jan 1993

An Optimal Nonblocking Multicast Virtual Circuit Switch, Jonathan S. Turner

All Computer Science and Engineering Research

This paper describes an architecture for a multicast virtual circuit switch using cell recycling. This is the first nonblocking switch architecture that is optimal in both the switching network complexity and the amount of memory required for multicast address translation. Furthermore, it is optimal in the amount of effort required for multicast connection modification. This architecture makes it both technically and economically feasible to construct the large switching systems that will ultimately be needed for wide scale deployment of Broadband ISDN to residential users. In particular, we estimate that systems with tens of thousands of 620 Mb/s ports can be …

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Segmentation/Recognition Of Hand-Written Numeral Characters, Khalid Sherdil Jan 1993

Segmentation/Recognition Of Hand-Written Numeral Characters, Khalid Sherdil

All Computer Science and Engineering Research

This thesis describes a number of techniques for segmenting non-cursive handwritten digits into individual characters. It strongly emphasizes on a recognition-segmentation algorithm, which uses the linear regression method to recognize those strokes which consist of one or more straight-lined parts. A new method of sampling the pen data according to the pen speed, hence giving a more uniform points concentratino distribution, is also introduced. It is shown how several of our segmenting techniques, such as relative stroke lengths, relative stroke positions, order of stroke entry, stroke direction, stroke intersection, etc. can be combined to yield success results of about 95%.

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Learning Unions Of Boxes With Membership And Equivalence Queries, Paul W. Goldberg, Sally A. Goldman, H. David Matthias Jan 1993

Learning Unions Of Boxes With Membership And Equivalence Queries, Paul W. Goldberg, Sally A. Goldman, H. David Matthias

All Computer Science and Engineering Research

We present two algorithms that use membership and equivalence queries to exactly identify the concepts given by the union of s discretized axis-parallel boxes in d-dimensional discretized Euclidean space where each coordinate can have n discrete values. The first algorithm receives at most s*d counterexamples and uses time and membership queries polynomial in s and logn for d any constant. Further, all equivalence queries made can be formulated as the union of O(s*d*log(s)) axis-parallel boxes. Next, we introduce a new complexity measure that better captures the complexity of a union of boxes than simply the number of boxes and dimensions. …

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The Washington University Multimedia Explorer, William D. Richard, Jerome R. Cox Jr., A. Maynard Engebretson, Jason Fritts, Craig Horn Jan 1993

The Washington University Multimedia Explorer, William D. Richard, Jerome R. Cox Jr., A. Maynard Engebretson, Jason Fritts, Craig Horn

All Computer Science and Engineering Research

The Washington University MultiMedia eXplorer (MMX) is a complete, host-independent multimedia system capable of transmitting and receiving JPEG-compressed video, CD-quality audio, and high-resolution radiographic images over the Washington University broadband ATM network. If the host is equipped with an ATM interface card, normal network traffic is supported via "T" and "Y" connections. The MMX consists of an ATMizer and three multimedia subsystems. The ATMizer implements the host interface, the interface to the ATM network, and the interface to the three multimdeia channels. This paper describes the architecture of the MMX, the software used with the system, and the applications which …

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On Minimizing Thermal Deflections Of Laminated Plates, Serge Abrate Jan 1993

On Minimizing Thermal Deflections Of Laminated Plates, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Thermal deflections of symmetrically laminated plates that are continuous over many line supports are determined using the Rayleigh-Ritz method. The constitutive equations and the thermal loads are expressed in terms of four non-dimensional lamination parameters. Layups that minimize thermal deflections are determined for several types of composite plates subjected to temperature increases that vary linearly through the thickness.

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Computer Simulation Of Three-Dimensional Mechanical Assemblies: Part I - General Formulation, Yong Fang, Frank W. Liou Jan 1993

Computer Simulation Of Three-Dimensional Mechanical Assemblies: Part I - General Formulation, Yong Fang, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In Part I of this paper, a dynamic modeling system for the simulation of three-dimensional mechanical assemblies is presented. With this simulation tool, a designer can interactively create an assembly of mechanical components ready for dynamic analysis. The modeling system presented in this paper include» the derivation of the equations of motion of spatial multi-body systems, and the formulation of the equations to model the associated collision detection and collision responses. Part II of this paper is to introduce the geometry modeling and computer simulation of 3D systems.

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A Magnetic Suspension System With A Large Angular Range, Colin P. Britcher, Mehran Ghofrani Jan 1993

A Magnetic Suspension System With A Large Angular Range, Colin P. Britcher, Mehran Ghofrani

Mechanical & Aerospace Engineering Faculty Publications

In order to explore and develop technology required for the magnetic suspension of objects over large ranges of orientation, a small-scale laboratory system, the large-angle magnetic suspension test fixture (LAMSTF) has been constructed at NASA Langley Research Center. This apparatus falls into the category of large-gap, actively stabilized magnetic levitation systems. The hardware comprises five conventional electromagnets in a circular arrangement, each driven from a separate bipolar power amplifier. Electromagnet currents are commanded by a digital control system, implemented on a microcomputer, which in turn derives the position and attitude of the suspended element from an infrared optical system. The …

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Glow-Discharge Enhanced Permeation Of Oxygen Through Silver, D. Wu, R. A. Outlaw, Robert L. Ash Jan 1993

Glow-Discharge Enhanced Permeation Of Oxygen Through Silver, D. Wu, R. A. Outlaw, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

The permeation of oxygen through Ag0.05Zr over the temperature range of 300-650°C under glow-discharge conditions has been studied and compared to the permeation of thermally dissociated molecular oxygen. A low-energy dc glow-discharge in O2 has been employed which produced approximately 10% atoms. The permeation rate during the glow discharge was found to be much higher (a factor of ∼10) than without the glow discharge. The small fraction of oxygen atoms generated appears to dominate the permeation because of much higher solution probabilities. Below 500°C, the activation energy for the permeation with glow discharge was found to be 15.5 kcal/mol …

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Test 1672: John Deere 8870 Powersync Diesel 12 And 24 Speeds, Nebraska Tractor Test Lab Jan 1993

Test 1672: John Deere 8870 Powersync Diesel 12 And 24 Speeds, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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Test 1664: John Deere 7600 Powerquad Diesel 16-Speed, Nebraska Tractor Test Lab Jan 1993

Test 1664: John Deere 7600 Powerquad Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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Test 1671: John Deere 8770 Powersync Diesel 12 And 24 Speeds, Nebraska Tractor Test Lab Jan 1993

Test 1671: John Deere 8770 Powersync Diesel 12 And 24 Speeds, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole Jan 1993

A Study Of Dynamic Optimization Techniques: Lessons And Directions In Kernel Design, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The Synthesis kernel [21,22,23,27,28] showed that dynamic code generation, software feedback, and fine-grain modular kernel organization are useful implementation techniques for improving the performance of operating system kernels. In addition, and perhaps more importantly, we discovered that there are strong interactions between the techniques. Hence, a careful and systematic combination of the techniques can be very powerful even though each one by itself may have serious limitations. By identifying these interactions we illustrate the problems of applying each technique in isolation to existing kernels. We also highlight the important common under-pinnings of the Synthesis experience and present our ideas on …

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Efficient Simulation Of Multicarrier Digital Communication Systems In Nonlinear Channel Environments, Kevin W. Schneider, William H. Tranter Jan 1993

Efficient Simulation Of Multicarrier Digital Communication Systems In Nonlinear Channel Environments, Kevin W. Schneider, William H. Tranter

Electrical and Computer Engineering Faculty Research & Creative Works

The effectiveness of computer simulation as a tool for the design and analysis of communication systems is often limited by the long execution times required for many simulations. When simulating multicarrier digital communication systems operating over nonlinear channels, the required high sampling rate contributes significantly to long execution times. A new method that reduces the sampling rate of simulations of such systems is developed. This Partial Sum of Products (ParSOP) method reduces the sampling rate by generating only the intermodulation products that lie in a frequency band of interest. The ParSOP method requires that the bandpass nonlinearity be represented by …

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An Optoelectronic Implementation Of The Adaptive Resonance Neural Network, Donald C. Wunsch, T. P. Caudell, R. J. Marks, R. A. Falk, C. David Capps Jan 1993

An Optoelectronic Implementation Of The Adaptive Resonance Neural Network, Donald C. Wunsch, T. P. Caudell, R. J. Marks, R. A. Falk, C. David Capps

Electrical and Computer Engineering Faculty Research & Creative Works

A solution to the problem of implementation of the adaptive resonance theory (ART) of neural networks that uses an optical correlator which allows the large body of correlator research to be leveraged in the implementation of ART is presented. The implementation takes advantage of the fact that one ART-based architecture, known as ART1, can be broken into several parts, some of which are better to implement in parallel. The control structure of ART, often regarded as its most complex part, is actually not very time consuming and can be done in electronics. The bottom-up and top-down gated pathways, however, are …

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Embankment Widening And Grade Raising On Soft Foundation Soils, Phase 2, Scott Ludlow, Wai-Fah Chen, Philippe L. Bourdeau, C. W. Lovell Jan 1993

Embankment Widening And Grade Raising On Soft Foundation Soils, Phase 2, Scott Ludlow, Wai-Fah Chen, Philippe L. Bourdeau, C. W. Lovell

JTRP Technical Reports

No abstract provided.

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Subgrade Resilient Modulus For Pavement Design And Evaluation, Woojin Lee, Nihal Chand Bohra, A. G. Altschaeffl, Thomas D. White Jan 1993

Subgrade Resilient Modulus For Pavement Design And Evaluation, Woojin Lee, Nihal Chand Bohra, A. G. Altschaeffl, Thomas D. White

JTRP Technical Reports

No abstract provided.

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Debonding In Pretensioned Beams-Precast Strands, Part 2: Simply Supported Tests, O. A. Abdalla, J. A. Ramirez, Robert H. Lee Jan 1993

Debonding In Pretensioned Beams-Precast Strands, Part 2: Simply Supported Tests, O. A. Abdalla, J. A. Ramirez, Robert H. Lee

JTRP Technical Reports

No abstract provided.

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Strand Debonding In Pretensioned Beams - Precast Prestressed Concrete Bridge Girders With Debonded Strands - Continuity Issues, O. A. Abdalla, J. A. Ramirez, Robert H. Lee Jan 1993

Strand Debonding In Pretensioned Beams - Precast Prestressed Concrete Bridge Girders With Debonded Strands - Continuity Issues, O. A. Abdalla, J. A. Ramirez, Robert H. Lee

JTRP Technical Reports

No abstract provided.

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Mathematical Modeling Of The Formation Of Calcareous Deposits On Cathodically Protected Steel In Seawater, J. F. Yan, T. V. Nguyen, Ralph E. White, R. B. Griffin Jan 1993

Mathematical Modeling Of The Formation Of Calcareous Deposits On Cathodically Protected Steel In Seawater, J. F. Yan, T. V. Nguyen, Ralph E. White, R. B. Griffin

Faculty Publications

A first principle mathematical model of the formation of calcareous deposits on a cathodically protected steel rotatingdisk electrode in seawater is presented. The model includes equations which transport phenomena, electrochemical reactions,precipitation reactions, and a homogeneous reaction involved in the formation of calcareous deposits on an electrodesurface. Predicted concentration profiles show that a high concentration of OH– ions on the electrode surface leads to the formation of calcareous deposits. The calcareous deposits contain mostly CaCO3, but the initial deposits are predicted to contain more Mg(OH)2 than CaCO3. The predicted calcareous deposits on the electrode surface …

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Parametric Studies Of The Formation Of Calcareous Deposits On Cathodically Protected Steel In Seawater, J. F. Yan, Ralph E. White, R. B. Griffin Jan 1993

Parametric Studies Of The Formation Of Calcareous Deposits On Cathodically Protected Steel In Seawater, J. F. Yan, Ralph E. White, R. B. Griffin

Faculty Publications

A first principle mathematical model has been used to study the effects of ocean environment and cathodic protection on the formation of calcareous deposits and their ability to reduce the cathodic current density. These parameters include applied potential, rotation speed, temperature, salinity, and depth. The results showed the applied potential strongly influences the formation of calcareous deposits and their ability to reduce the cathodic current density. Among the environmental factors, rotation speed has the most influence on the cathodic current density. Salinity slightly influences the cathodic current density over the range of interest. Temperature is much more influential than salinity …

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A Water And Heat Management Model For Proton-Exchange-Membrane Fuel Cells, Trung V. Nguyen, Ralph E. White Jan 1993

A Water And Heat Management Model For Proton-Exchange-Membrane Fuel Cells, Trung V. Nguyen, Ralph E. White

Faculty Publications

Proper water and heat management are essential for obtaining high-power-density performance at high energy efficiency for proton-exchange-membrane fuel cells. A water and heat management model was developed and used to investigate the effectiveness of various humidification designs. The model accounts for water transport across the membrane by electro-osmosis and diffusion, heat transfer from the solid phase to the gas phase and latent heat associated with water evaporation and condensation in the flow channels. Results from the model showed that at high current densities (> 1 A/cm2) ohmic loss in the membrane accounts for a large fraction of the …

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Design And Construction Of Maintainable Knowledge Bases Through Effective Use Of Entity-Relationship Modeling Techniques, William Yancey Pike Jan 1993

Design And Construction Of Maintainable Knowledge Bases Through Effective Use Of Entity-Relationship Modeling Techniques, William Yancey Pike

Retrospective Theses and Dissertations

The use of an accepted logical database design tool, Entity-Relationship Diagrams (E-RD), is explored as a method by which conceptual and pseudo-conceptual knowledge bases may be designed. Extensions to Peter Chen's classic E-RD method which can model knowledge structure used by knowledge-based applications are explored. The use of E-RDs to design knowledge bases is proposed as a two-stage process. In the first stage, and E-RD, termed the Essential E-RD, is developed of the realm of the problem or enterprise being modeled. The Essential E-RD is completely independent of any knowledge representation model (KRM) and is intended for the understanding of …

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Automatic Color Segmentation Algorithms-With Application To Skin Tumor Feature Identification, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker, G. A. Hance Jan 1993

Automatic Color Segmentation Algorithms-With Application To Skin Tumor Feature Identification, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker, G. A. Hance

Electrical and Computer Engineering Faculty Research & Creative Works

Two color-image segmentation methods are described. The first is based on a spherical coordinate transform of original RGB data. The second is based on a mathematically optimal transform, the principal components transform (also known as eigenvector, discrete Karhunen-Loeve, or Hotelling transform). These algorithms are applied to the extraction from skin tumor images of various features such as tumor border, crust, hair scale, shiny areas, and ulcer. The results of this research will be used in the development of a computer vision system that will serve as the visual front-end of a medical expert system to automate visual feature identification for …

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Nebraska Summary: S171 Massey Ferguson 3075, Nebraska Tractor Test Lab Jan 1993

Nebraska Summary: S171 Massey Ferguson 3075, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

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Nebraska Summary: S145 Case-Ih 5250, Nebraska Tractor Test Lab Jan 1993

Nebraska Summary: S145 Case-Ih 5250, Nebraska Tractor Test Lab

Nebraska Tractor Tests

ABOUT THE TEST REPORT AND USE OF THE DATA The test data contained in this report are a tabulation of the results of a series of tests. Due to the restricted format of these pages, only a limited amount of data and not all of the tractor specifications are included. The full OECD report contains usually about 30 pages of data and specifications. The test data were obtained for each tractor under similar conditions and therefore, provide a means of comparison of performance based on a limited set of reported data. EXPLANATION OF THE TEST PROCEDURES Purpose The purpose of …

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Test 1663: Case International 7150 And 7250 Diesels 18-Speed, Nebraska Tractor Test Lab Jan 1993

Test 1663: Case International 7150 And 7250 Diesels 18-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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Test 1665: John Deere 7600 Powershift Diesel 19-Speed, Nebraska Tractor Test Lab Jan 1993

Test 1665: John Deere 7600 Powershift Diesel 19-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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Test 1666: John Deere 7700 Powerquad Diesel 16-Speed, Nebraska Tractor Test Lab Jan 1993

Test 1666: John Deere 7700 Powerquad Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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Test 1673: John Deere 8970 Powersync Diesel 12 And 24 Speed, Nebraska Tractor Test Lab Jan 1993

Test 1673: John Deere 8970 Powersync Diesel 12 And 24 Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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Test 1668: John Deere 7800 Powerquad Diesel 16-Speed, Nebraska Tractor Test Lab Jan 1993

Test 1668: John Deere 7800 Powerquad Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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