11 research outputs found
Numerical Simulation-Based Optimization of Contact Stress Distribution and Lubrication Conditions in the Straight Worm Drive
Tooth contact area optimization/meshing of the straight worm pair is vital for improving its operation efficiency. Geometric parameters of a worm helicoid were derived via the gear meshing theory using the equations of the instantaneous contact line. The visualization function and powerful computing capability of MATLAB are used for the numerical analysis where the instantaneous contact line distribution is simulated for particular worm drive parameters, which yields the induced curvature and slip angle in the direction of the line. The above results are used for further optimization of the meshing performance of the straight worm gear and identification of its influencing factors. A case study of the particular cylindrical worm gear in compliance with the GB 10085-1988 Standard of China demonstrate that a reasonable selection of worm gear parameters can extend the contact line and the working range of the tooth surface of the worm gear and/or make the contact line distribution along the worm wheel more uniform, thus improving the local meshing performanceΠΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΡ Π·ΡΠ±ΡΠ°ΡΠΎΠΉ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ½ΠΎΠΉ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ/Π·Π°ΡΠ΅ΠΏΠ»Π΅Π½ΠΈΠ΅ ΠΏΡΡΠΌΠΎΠ»ΠΈΠ½Π΅ΠΉΠ½ΠΎΠΉ ΡΠ΅ΡΠ²ΡΡΠ½ΠΎΠΉ ΠΏΠ°ΡΡ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡ ΠΏΠΎΠ²ΡΡΠ΅Π½ΠΈΠ΅ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ Π΅Π΅ ΡΠΊΡΠΏΠ»ΡΠ°ΡΠ°ΡΠΈΠΈ. ΠΠ΅ΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ ΡΠ΅ΡΠ²ΡΡΠ½ΠΎΠ³ΠΎ Π³Π΅Π»ΠΈΠΊΠΎΠΈΠ΄Π° ΠΏΠΎΠ»ΡΡΠ΅Π½Ρ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΡΠ΅ΠΎΡΠΈΠΈ Π·Π°ΡΠ΅ΠΏΠ»Π΅Π½ΠΈΡ Π·ΡΠ±ΡΠ°ΡΡΡ
ΠΊΠΎΠ»Π΅Ρ ΠΈ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Π»ΠΈΠ½ΠΈΠΈ ΠΌΠ³Π½ΠΎΠ²Π΅Π½Π½ΠΎΠ³ΠΎ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ°. Π§ΠΈΡΠ»Π΅Π½Π½ΡΠΉ Π°Π½Π°Π»ΠΈΠ· ΠΎΡΠ½ΠΎΠ²Π°Π½ Π½Π° ΡΡΠ½ΠΊΡΠΈΠΈ Π²ΠΈΠ·ΡΠ°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΠΈ Π²ΡΡΠΈΡΠ»ΠΈΡΠ΅Π»ΡΠ½ΡΡ
Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΡΡ
ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΡ MATLAB, ΡΡΠΎ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°ΡΡ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ Π½Π° Π»ΠΈΠ½ΠΈΠΈ ΠΌΠ³Π½ΠΎΠ²Π΅Π½Π½ΠΎΠ³ΠΎ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ° Π΄Π»Ρ ΡΠΏΠ΅ΡΠΈΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΡΠ΅ΡΠ²ΡΡΠ½ΠΎΠ³ΠΎ ΠΏΡΠΈΠ²ΠΎΠ΄Π°, ΡΠΎΠ·Π΄Π°Π²Π°Ρ Π²ΡΠ½ΡΠΆΠ΄Π΅Π½Π½ΡΡ ΠΊΡΠΈΠ²ΠΈΠ·Π½Ρ ΠΈ ΡΠ³ΠΎΠ» ΡΠΊΠΎΠ»ΡΠΆΠ΅Π½ΠΈΡ Π² Π½Π°ΠΏΡΠ°Π²Π»Π΅Π½ΠΈΠΈ ΡΡΠΎΠΉ Π»ΠΈΠ½ΠΈΠΈ. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΠ²Π°ΡΡ ΠΏΠΎΡΠ»Π΅Π΄ΡΡΡΡΡ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΡ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² Π·Π°ΡΠ΅ΠΏΠ»Π΅Π½ΠΈΡ ΠΏΡΡΠΌΠΎΠ»ΠΈΠ½Π΅ΠΉΠ½ΠΎΠΉ ΡΠ΅ΡΠ²ΡΡΠ½ΠΎΠΉ ΠΏΠ΅ΡΠ΅Π΄Π°ΡΠΈ ΠΈ ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½ΠΈΠ΅ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡΠΈΡ
ΡΠ°ΠΊΡΠΎΡΠΎΠ². ΠΡΠΈΠΌΠ΅Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΡ ΡΠΏΠ΅ΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΈΠ»ΠΈΠ½Π΄ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅ΡΠ²ΡΡΠ½ΠΎΠΉ ΠΏΠ΅ΡΠ΅Π΄Π°ΡΠΈ Π² ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΠΈΠΈ ΡΠΎ ΡΡΠ°Π½Π΄Π°ΡΡΠΎΠΌ ΠΠΈΡΠ°Ρ (GB 10085-1988) ΠΏΠΎΠΊΠ°Π·ΡΠ²Π°Π΅Ρ, ΡΡΠΎ ΡΠ°ΡΠΈΠΎΠ½Π°Π»ΡΠ½ΡΠΉ Π²ΡΠ±ΠΎΡ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΡΡΠΎΠΉ ΠΏΠ΅ΡΠ΅Π΄Π°ΡΠΈ ΠΌΠΎΠΆΠ΅Ρ ΡΠ²Π΅Π»ΠΈΡΠΈΡΡ Π»ΠΈΠ½ΠΈΡ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ°, Π° ΡΠ°ΠΊΠΆΠ΅ ΡΠ°ΡΡΠΈΡΠΈΡΡ ΡΠ°Π±ΠΎΡΠΈΠΉ Π΄ΠΈΠ°ΠΏΠ°Π·ΠΎΠ½ Π΅Π΅ Π·ΡΠ±ΡΠ°ΡΠΎΠΉ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΈ/ΠΈΠ»ΠΈ ΠΎΠ±Π΅ΡΠΏΠ΅ΡΠΈΡΡ Π±ΠΎΠ»Π΅Π΅ ΡΠ°Π²Π½ΠΎΠΌΠ΅ΡΠ½ΡΠΉ ΠΊΠΎΠ½ΡΠ°ΠΊΡ ΠΏΠΎ ΡΠ΅ΡΠ²ΡΡΠ½ΠΎΠΌΡ ΠΊΠΎΠ»Π΅ΡΡ, ΠΏΠΎΠ²ΡΡΠ°Ρ ΡΠ΅ΠΌ ΡΠ°ΠΌΡΠΌ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π»ΠΎΠΊΠ°Π»ΡΠ½ΠΎΠ³ΠΎ Π·Π°ΡΠ΅ΠΏΠ»Π΅Π½ΠΈΡ
The kinematic analysis and metrology of cylindrical worm gearing
PhD ThesisWorm gearing is very widely used, especially in heavy industry, but due to the complexity
of worm gear geometry, worm gear research has lagged behind that for spur and helical
gears. In the last decade, however, the potential for significant improvement in worm
gearing has dramatically increased: computers have given greater freedom to analyse
worm gearing; CNC machines make it possible to aim for optimised worm gear
geometries with very high accuracy and the development of synthetic lubricants has
substantially improved lubrication conditions. In the UK, over the last few years, research
effort in the field of worm gearing has increased considerably.
As a part of this recent activity in the UK, the author has been involved mainly in
developing the analytical mechanics and metrology of worm gears. A method for the
generalised 3D non-elastic worm gear mesh analysis and associated software have been
developed and worm wheel metrology software has been implemented on a CNC
measuring machine in the UK National Gear Metrology Laboratory, to allow, for the first
time, analytical measurement of worm wheel tooth flanks. Combination of the mesh
analysis software and CNC measurement of worm wheels has assisted in the design and
manufacture of worm gears with modified tooth profiles.
Two methods of 3D non-elastic worm gear analysis have been developed for conjugate
action and non-conjugate action respectively. The conjugate analysis determines the
lines of contact, sliding and rolling velocities, limitations of the working area (the envelope
of contact lines on a worm surface and singularities on a wheel surface), principal
relative curvatures and the orientations of contact lines. It is based on the B-matrix
method [Zhang and Hu, 1989]. The non-conjugate analysis predicts entry and exit gaps,
contact ratio, wear marking on the worm flank, instantaneous contact topology on all the
engaged tooth flanks, total contact area, contact pattern and transmission error. This is
based on numerical simulation of the actual worm gear running process under no-load.
Although the non-elastic analysis models have been designed for any type of worm
gearing, and have been used to study Cavex (ZC) wormgears and the meshing of a ZA
Abstract
worm with a helical gear, most of the work has been on involute (ZI) worm gearing, since
this is, by far, the most commonly produced type in the UK.
This thesis presents the work as follows:
1) The development of the B-Matrix kinematic method for conjugate analysis.
The B-Matrix method, presented in chapter 2, elegantly simplifies the derivation and
calculation procedures, since the geometric parameters and the motional parameters can
be arranged in separate matrices. As a result, the models can be applied to different
geometries and coordinate systems with no need for further difficult derivations. The
method leads to an easier way of integrating the theory of various types of worm gearing
into compact generalised models. It is much more convenient and reliable to let the
computer formulate and solve matrix equations numerically, treating each matrix as a
simple variable, than to develop analytically the corresponding long tedious non-linear
equations.
2) The development of mathematical equations to allow CNC measuring machines to
measure cylindrical worm wheels with respect to their mating worms.
The measurements are 3-dimensional and absolute, in the sense that the results are the
deviations from the theoretical geometries rather than comparative measurements
relative to a (necessarily imperfect) master worm wheel. The measurement theory has
been implemented on a particular CNC measuring machine. This is presented in
chapters 3 and 5.
3) The development of the non-conjugate analysis.
The fundamental basis of the non-conjugate analysis presented in this thesis is to rotate
the worm wheel to bring its tooth flank into contact with the worm flank at each given
angle of worm rotation, so that the no-load transmission error and gap contours can be
determined. This method is suitable for both cylindrical and globoidal worm gears, since
the rotation angles of worm and wheel are used to simulate the running process directly.
Abstract
The method also allows the wheel tooth flank to be obtained either by conjugate analysis
of the hobbing process, or by analytical measurements or other methods (for example,
when a theoretically-generated involute helical gear is used to mesh with a worm). This
work is presented in chapter 4.
4) implementation of the non-elastic analysis theory.
The non-elastic analysis software has been written for personal computers. In addition,
dimensional calculations specified by BS 721 and commonly used hob design methods
have been added to the non-elastic analysis software to increase user-friendliness. The
software has been used to investigate the effects on the worm gear contact and
performance of machining errors and profile deviations or modifications. The structure
of this analysis software allows for the inclusion of new modules for other types of worm
gearing without in any way disturbing the integrity of the program's existing abilities. The
non-elastic analysis software is user-friendly with a "Windows" graphical user interface.
Software reliability and error tolerance have been of particular concern during program
development. This work is presented in chapter 5.
5) The software has been thoroughly validated against other published results and/or
actual production.
The software has been used extensively for both research and commercial purposes,
and the user interface developed further in response to user feedback. Examples of
these applications are given in chapter 7
Abstracts on Radio Direction Finding (1899 - 1995)
The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography).
Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM.
The contents of these files are:
1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format];
2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format];
3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion
A complex systems approach to education in Switzerland
The insights gained from the study of complex systems in biological, social, and engineered systems enables us not only to observe and understand, but also to actively design systems which will be capable of successfully coping with complex and dynamically changing situations. The methods and mindset required for this approach have been applied to educational systems with their diverse levels of scale and complexity. Based on the general case made by Yaneer Bar-Yam, this paper applies the complex systems approach to the educational system in Switzerland. It confirms that the complex systems approach is valid. Indeed, many recommendations made for the general case have already been implemented in the Swiss education system. To address existing problems and difficulties, further steps are recommended. This paper contributes to the further establishment complex systems approach by shedding light on an area which concerns us all, which is a frequent topic of discussion and dispute among politicians and the public, where billions of dollars have been spent without achieving the desired results, and where it is difficult to directly derive consequences from actions taken. The analysis of the education system's different levels, their complexity and scale will clarify how such a dynamic system should be approached, and how it can be guided towards the desired performance
Information technology and military performance
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Political Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 519-544).Militaries have long been eager to adopt the latest technology (IT) in a quest to improve knowledge of and control over the battlefield. At the same time, uncertainty and confusion have remained prominent in actual experience of war. IT usage sometimes improves knowledge, but it sometimes contributes to tactical blunders and misplaced hubris. As militaries invest intensively in IT, they also tend to develop larger headquarters staffs, depend more heavily on planning and intelligence, and employ a larger percentage of personnel in knowledge work rather than physical combat. Both optimists and pessimists about the so-called "revolution in military affairs" have tended to overlook the ways in which IT is profoundly and ambiguously embedded in everyday organizational life. Technocrats embrace IT to "lift the fog of war," but IT often becomes a source of breakdowns, misperception, and politicization. To describe the conditions under which IT usage improves or degrades organizational performance, this dissertation develops the notion of information friction, an aggregate measure of the intensity of organizational struggle to coordinate IT with the operational environment. It articulates hypotheses about how the structure of the external battlefield, internal bureaucratic politics, and patterns of human-computer interaction can either exacerbate or relieve friction, which thus degrades or improves performance. Technological determinism alone cannot account for the increasing complexity and variable performances of information phenomena. Information friction theory is empirically grounded in a participant-observation study of U.S. special operations in Iraq from 2007 to 2008. To test the external validity of insights gained through fieldwork in Iraq, an historical study of the 1940 Battle of Britain examines IT usage in a totally different structural, organizational, and technological context.(cont.) These paired cases show that high information friction, and thus degraded performance, can arise with sophisticated IT, while lower friction and impressive performance can occur with far less sophisticated networks. The social context, not just the quality of technology, makes all the difference. Many shorter examples from recent military history are included to illustrate concepts. This project should be of broad interest to students of organizational knowledge, IT, and military effectiveness.by Jon Randall Lindsay.Ph.D
Bowdoin Orient v.137, no.1-25 (2007-2008)
https://digitalcommons.bowdoin.edu/bowdoinorient-2000s/1008/thumbnail.jp
The Whitworthian 2001-2002
The Whitworthian student newspaper, September 2001-April 2002.https://digitalcommons.whitworth.edu/whitworthian/1085/thumbnail.jp
Maritime expressions:a corpus based exploration of maritime metaphors
This study uses a purpose-built corpus to explore the linguistic legacy of Britainβs maritime history found in the form of hundreds of specialised βMaritime Expressionsβ (MEs), such as TAKEN ABACK, ANCHOR and ALOOF, that permeate modern English. Selecting just those expressions commencing with βAβ, it analyses 61 MEs in detail and describes the processes by which these technical expressions, from a highly specialised occupational discourse community, have made their way into modern English. The Maritime Text Corpus (MTC) comprises 8.8 million words, encompassing a range of text types and registers, selected to provide a cross-section of βmaritimeβ writing. It is analysed using WordSmith analytical software (Scott, 2010), with the 100 million-word British National Corpus (BNC) as a reference corpus. Using the MTC, a list of keywords of specific salience within the maritime discourse has been compiled and, using frequency data, concordances and collocations, these MEs are described in detail and their use and form in the MTC and the BNC is compared. The study examines the transformation from ME to figurative use in the general discourse, in terms of form and metaphoricity. MEs are classified according to their metaphorical strength and their transference from maritime usage into new registers and domains such as those of business, politics, sports and reportage etc. A revised model of metaphoricity is developed and a new category of figurative expression, the βresonatorβ, is proposed. Additionally, developing the work of Lakov and Johnson, Kovesces and others on Conceptual Metaphor Theory (CMT), a number of Maritime Conceptual Metaphors are identified and their cultural significance is discussed