931 resultados para Friction laws


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There is no definite theory yet for the mechanism by which the pattern of epidermal ridges on fingers, palms and soles forming friction ridge skin (FRS) patterns is created. For a long time growth forces in the embryonal epidermis have been believed to be involved in FRS formation. More recent evidence suggests that Merkel cells play an important part in this process as well. Here we suggest a model for the formation of FRS patterns that links Merkel cells to the epidermal stress distribution. The Merkel cells are modeled as agents in an agent based model that move anisotropically where the anisotropy is created by the epidermal stress tensor. As a result ridge patterns are created with pattern defects as they occur in real FRS patterns. As a consequence we suggest why the topology of FRS patterns is indeed unique as the arrangement of pattern defects is sensitive to the initial configuration of Merkel cells.

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Research project HR-234 was sponsored by the Iowa Highway Research Board and the Iowa Department of Transportation. In the preparation of this compilation of highway and street laws of Iowa, an attempt has been made to include those sections of the Code to which reference is frequently required by the Department of Transportation, counties, cities and towns in their conduct of highway and street administration, construction and maintenance. Because of the broad scope of highway and street work and the many interrelated provisions of Iowa law, and in the interests of keeping this volume in a convenient and usable size, some Code provisions which have some bearing on the principal subject were of necessity omitted. The volume has been compiled in loose leaf form with the expectation that periodic updates will keep the reader informed regarding changes in the law and/or new laws. A general index is provided at the end of the text of this volume. Each major topic is divided into relevant subtopics and are accompanied by appropriate Code sections. This publication is offered with the hope and belief that it will prove to be of value and assistance to those concerned with the problems of establishing, maintaining and administering a highway and street system. The reader is cautioned to consult legal counsel on all matters beyond the scope of this text.

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This project involved the evaluation of several aggregates previously rated poor to excellent with respect to skid resistance and certain mix design parameters. An open graded asphalt friction course was evaluated using 4 comparably graded aggregates: quartzite, fine grained limestone, coarse limestone and lightweight expanded shale. The performance investigations involved the verification of observations of the quartzite test sections, evaluation of the effect of blending the superior quartzite with a typical coarse grained-textured limestone, and the evaluation of the limestone. The effects of traffic on the aggregates used in the test sections were studied, as well as the relationship between asphalt content levels and traffic with respect to performance. The bond of the open graded friction course mixture was also evaluated. The SN performance of all test sections after sixteen months of exposure was found to be satisfactory in that none of the material combinations had polished to the point where unacceptable SN levels developed. When material combinations were compared, significant differences were noted.

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Iowa’s alcoholic beverages industry operates within the confines of a carefully cast partnership between the Iowa Alcoholic Beverages Division (Division), licensees and law enforcement officials. Close cooperation among these three entities is essential for regulation and enforcement of Iowa’s alcoholic beverages laws in order to achieve compliance. This manual was developed to provide licensees (their employees and agents) with the information needed to protect the welfare and safety of Iowans through compliance with laws addressing the manufacture, distribution and sale of alcoholic beverages.

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A synopsis of Iowa boating regulations. This synopsis is not intended to quote the complete law, but rather to present a summary of the various regulations concerning safe boating. These guidelines are, however, included as regulations in the Code of Iowa and the Administrative Code.

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The extra session of the 1840 legislative assembly listing all of the territorial laws of Iowa. The dates of approval of the acts are listed after each one and a brief index is included. This is the 1902 reprint by the Historical Department of Iowa.

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The kinetics and microstructure of solid-phase crystallization under continuous heating conditions and random distribution of nuclei are analyzed. An Arrhenius temperature dependence is assumed for both nucleation and growth rates. Under these circumstances, the system has a scaling law such that the behavior of the scaled system is independent of the heating rate. Hence, the kinetics and microstructure obtained at different heating rates differ only in time and length scaling factors. Concerning the kinetics, it is shown that the extended volume evolves with time according to αex = [exp(κCt′)]m+1, where t′ is the dimensionless time. This scaled solution not only represents a significant simplification of the system description, it also provides new tools for its analysis. For instance, it has been possible to find an analytical dependence of the final average grain size on kinetic parameters. Concerning the microstructure, the existence of a length scaling factor has allowed the grain-size distribution to be numerically calculated as a function of the kinetic parameters

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This leaflet gives information on how to start a free public library in a community. Includes regulations and related laws dealing with libraries.

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This publication is produced by the Legislative Services Agency. This publication contains all election laws to be included in the 2014 Iowa Code. Changes in Code language to be included in the 2014 Iowa Code are marked by highlighting in yellow. Code sections with changes are also highlighted in yellow in the Table of Contents.

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As an employer, you are always seeking good employees to add to your business. Many youth are eager to work in Iowa, especially during the summer months.To a teenager, a job means money for school and other expenses, work experience and help in deciding on a career.

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Wet pavement friction is known to be one of the most important roadway safety parameters. In this research, frictional properties of flexible (asphalt) pavements were investigated. As a part of this study, a laboratory device to polish asphalt specimens was refined and a procedure to evaluate mixture frictional properties was proposed. Following this procedure, 46 different Superpave mixtures, one stone matrix asphalt (SMA) mixture and one porous friction course (PFC) mixture were tested. In addition, 23 different asphalt and two concrete field sections were also tested for friction and noise. The results of both field and laboratory measurements were used to develop an International Friction Index (IFI)-based protocol for measurement of the frictional characteristics of asphalt pavements for laboratory friction measurements. Based on the results of the study, it appears the content of high friction aggregate should be 20% or more of the total aggregate blend when used with other, polish susceptible coarse aggregates; the frictional properties increased substantially as the friction aggregate content increased above 20%. Both steel slag and quartzite were found to improve the frictional properties of the blend, though steel slag had a lower polishing rate. In general, mixes containing soft limestone demonstrated lower friction values than comparable mixes with hard limestone or dolomite. Larger nominal maximum aggregate size mixes had better overall frictional performance than smaller sized mixes. In addition, mixes with higher fineness moduli generally had higher macrotexture and friction.

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In the preparation of this compilation of drainage laws of Iowa, an attempt has been made to include those sections of the Code to which reference is frequently required by the State Highway Commission, Boards of Supervisors and County Engineers in the conduct of highway and road administration as it is affected by the Iowa drainage laws. Of necessity some Code provisions which have a bearing on the principal subject were omitted. Enactments of the 56th General Assembly which modify existing code sections have been included as part of the regular text of the Code sections included in this publication. THE USER IS CAUTIONED THAT THESE CODE SECTIONS, AS MODIFIED BY THE 56th GENERAL ASSEMBLY, ARE NOT A PART OF THE 1954 CODE OF IOWA AND ARE OFFICIAL ONLY INSOFAR AS THEY ARE PRINTED IN THE OFFICIAL PUBLICATION ACTS OF THE 56TH GENERAL ASSEMBLY. SINCE THE 57TH GENERAL ASSEMBLY IS IN SESSION DURING THE PRINTING OF THIS PUBLICATION, ENACTMENTS OF THAT BODY WHICH AMEND OR REPEAL SECTIONS SET OUT HEREIN ARE INCLUDED IN THE BACK OF THIS VOLUME ON THE PINK-COLORED PAPER. THE USER IS CAUTIONED IN USING THIS VOLUME TO REFER TO THE TABLE OF SECTIONS REPEALED OR AMENDED, ON THE PINK-COLORED PAPER AT THE BACK OF THIS VOLUME. This publication is offered with the hope and belief that it will prove to be of value and assistance to those concerned with the problems of administering a highway, road and drainage system.

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The Americans with Disabilities Act (ADA) and the Fair Housing Act (FHA) prohibit discrimination on the basis of disability and govern the use of service or emotional support animals in places where pets may not be permitted. However, courts have been struggling with how to define and treat animals that qualify for protection under each law. This has created confusion as to what rights and duties are owed disabled persons and the animals that live with or accompany them. This essay attempts to clarify these two federal laws with regard to service or emotional support animals and the differing parties‘ rights and interests. It also includes an overview of select state laws that govern assistance animals of all types and our recommendations for enhancing the Iowa Civil Rights Act.