On Line Screw Systems and Their Application to Flexure Synthesis

2010 ◽  
Author(s):  
Hai-Jun Su ◽  
Hafez Tari
Keyword(s):  
Case Studies ◽  
Computational Algorithm ◽  
Necessary Conditions ◽  
Screw Theory ◽  
Motion Pattern ◽  
Linearly Independent ◽  
On Line ◽  
Sufficient And Necessary Conditions ◽  
The Given

This paper presents a new screw theory that deals with “lines” and “line systems”. A line is a screw with a zero pitch. A rank m screw system is called a line screw system if it contains m linearly independent lines. The set of lines within a screw system is called the line variety. A general m-system is a line screw system if the rank of its line variety equals m. This paper will answer two questions: (1) how to calculate the rank of the line variety for a given m-system and (2) how to algorithmically find a set of linearly independent lines from the given screw system. The motivation of this work comes from flexure synthesis whose goal is to find a pattern of flexures to achieve a specified motion. It has been previously found that a wire flexure is considered a line screw, or more specifically a pure force wrench. The synthesis of flexures is to remove undesired motion by applying constraints with flexures. By following reciprocity and definitions of line screws, we have derived the sufficient and necessary conditions of line screw systems. When applied to flexure synthesis, we show that not all motion pattern can be realized with wire flexures connected in parallel. A computational algorithm based on the line screw theory is developed to find all admissible line screws or force wrenches for a given motion space. At last two flexure synthesis case studies are provided to demonstrate the theory and the algorithm.

On Line Screw Systems and Their Application to Flexure Synthesis

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Hai-Jun Su ◽  
Hafez Tari
Keyword(s):  
Case Studies ◽  
Computational Algorithm ◽  
Screw Theory ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Constrained Motion ◽  
Motion Patterns ◽  
Linearly Independent ◽  
On Line ◽  
Necessary And Sufficient

Motivated by the problem of synthesizing a pattern of flexures that provide a desired constrained motion, this paper presents a new screw theory that deals with “line screws” and “line screw systems.” A line screw is a screw with a zero pitch. The set of all line screws within a screw system is called a line variety. A general screw system of rank m is a line screw system if the rank of its line variety equals m. This paper answers two questions: (1) how to calculate the rank of a line variety for a given screw system and (2) how to algorithmically find a set of linearly independent lines from a given screw system. It has been previously found that a wire or beam flexure is considered a line screw, or more specifically a pure force wrench. By following the reciprocity and definitions of line screws, we have derived the necessary and sufficient conditions of line screw systems. When applied to flexure synthesis, we show that not all motion patterns can be realized with wire flexures connected in parallel. A computational algorithm based on this line screw theory is developed to find a set of admissible line screws or force wrenches for a given motion space. Two flexure synthesis case studies are provided to demonstrate the theory and the algorithm.

Control of Steam-Turbine Regulators at Transition to an Island State

2009 ◽  
Vol 25 (25) ◽  
pp. 73-76
Author(s):  
Georgi Georgiev
Keyword(s):  
Steam Turbine ◽  
Dynamic Stability ◽  
Easy Problem ◽  
Island State ◽  
On Line ◽  
State Regime ◽  
Turbine Speed ◽  
The Given ◽  
Operating Algorithm

Control of Steam-Turbine Regulators at Transition to an Island StateThe simple operating algorithm is presented for steam turbine regulators of type Simadin (Siemens) at emergency switching-off of the generator from system together with some, unknown in advance, load. The given situation is known as "a transition to an island state (regime)". Keeping of turbine speed and preservation of its rating value at a generator blackout when its own needs will be load only, is an easy problem. When the generator remains in its island it is necessary to solve "on-line" two additional problems: to reveal a situation "island" and to estimate the island load for translating a regulator on the new task and providing dynamic stability of transition. The algorithm was tried and entered successfully into practice on Varna TPP, CEZ GROUP (Prague), in 2008.

RECYCLED WATER RISK PERCEPTION - A COMPARISON OF TWO CASE STUDIES

2007 ◽  
Vol 2 (4) ◽  
Author(s):  
A. Hurlimann
Keyword(s):  
Risk Perception ◽  
Case Studies ◽  
Perceived Risk ◽  
Capital City ◽  
Recycled Water ◽  
Urban Centre ◽  
On Line ◽  
Line Survey ◽  
Water Uses

This paper reports results from a study comparing perceived risk associated with various recycled water uses in two Australian locations, both in the state of Victoria: the capital city Melbourne, and Bendigo a regional urban centre. Both locations are experiencing ‘drought’, but Bendigo is experiencing this in a more acute manner. A case study is used in each location. Both case studies involve future use of recycled water in new commercial buildings. An on-line survey was used to measure attitudes to recycled water of the future occupants of both buildings. The study found perceived risk associated with 11 uses of recycled water increased as the use became increasingly personal. Interestingly, no difference in perceived risk associated with 11 uses of recycled water was found between locations. Prior experience (use) of recycled water was found to be a significant and positive factor in reducing risk perception. Various attitudinal variables were found to be significant influences on perceived risk. Results indicate that reducing perceived risk of recycled water use may increase satisfaction with its use.

The Development of the Communication Skills of Individuals Living in Homes for People with Disabilities

2012 ◽  
Vol 2 (2) ◽  
pp. 56-70
Author(s):  
Petr Kopečný
Keyword(s):  
Czech Republic ◽  
Case Studies ◽  
Social Services ◽  
Communication Skills ◽  
Speech Therapy ◽  
People With Disabilities ◽  
Educational Support ◽  
The Czech Republic ◽  
The Subject ◽  
The Given

This paper concentrates on the area of special educational support provided to individuals living in homes for people with disabilities in the Czech Republic and presents partial research results illustrating the state of the provision of speech therapy to users of social services facilities falling under the jurisdiction of the Ministry of Labour and Social Affairs. The subject of the research is an analysis of support for the development of the communication skills of pupils living in social services facilities. The partial results of the research outline the approaches employed by the managerial staff of the given facilities in implementing special educational procedures, describe forms of speech therapy provision in homes for people with disabilities, and compare the attitudes of teachers and social services staff to the development of communication with the importance attributed to it by speech therapists and demonstrated by the case studies performed.

scholarly journals A Discussion of a Cryptographical Scheme Based in F-Critical Sets of a Latin Square

Mathematics ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 285
Author(s):  
Laura M. Johnson ◽  
Stephanie Perkins
Keyword(s):  
Necessary Conditions ◽  
Latin Square ◽  
Latin Squares ◽  
Critical Sets ◽  
Long Cycles ◽  
The Given

This communication provides a discussion of a scheme originally proposed by Falcón in a paper entitled “Latin squares associated to principal autotopisms of long cycles. Applications in cryptography”. Falcón outlines the protocol for a cryptographical scheme that uses the F-critical sets associated with a particular Latin square to generate access levels for participants of the scheme. Accompanying the scheme is an example, which applies the protocol to a particular Latin square of order six. Exploration of the example itself, revealed some interesting observations about both the structure of the Latin square itself and the autotopisms associated with the Latin square. These observations give rise to necessary conditions for the generation of the F-critical sets associated with certain autotopisms of the given Latin square. The communication culminates with a table which outlines the various access levels for the given Latin square in accordance with the scheme detailed by Falcón.

scholarly journals Oscillation of Second-Order Differential Equations with Multiple and Mixed Delays under a Canonical Operator

Mathematics ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1323
Author(s):  
Shyam Sundar Santra ◽  
Rami Ahmad El-Nabulsi ◽  
Khaled Mohamed Khedher
Keyword(s):  
Differential Equations ◽  
Necessary Conditions ◽  
Second Order ◽  
Multiple Delays ◽  
Mixed Delays ◽  
Neutral Differential Equations ◽  
Canonical Operator ◽  
Second Order Differential Equations ◽  
The Future ◽  
Sufficient And Necessary Conditions

In this work, we obtained new sufficient and necessary conditions for the oscillation of second-order differential equations with mixed and multiple delays under a canonical operator. Our methods could be applicable to find the sufficient and necessary conditions for any neutral differential equations. Furthermore, we proved the validity of the obtained results via particular examples. At the end of the paper, we provide the future scope of this study.

scholarly journals Properties of Certain Subclass of Meromorphic Multivalent Functions Associated with q-Difference Operator

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1035
Author(s):  
Cai-Mei Yan ◽  
Rekha Srivastava ◽  
Jin-Lin Liu
Keyword(s):  
Difference Operator ◽  
Necessary Conditions ◽  
Partial Sums ◽  
Coefficient Estimates ◽  
Radius Of Starlikeness ◽  
Closure Theorems ◽  
Sufficient And Necessary Conditions ◽  
Distortion Theorems ◽  
Growth And Distortion Theorems

A new subclass Σp,q(α,A,B) of meromorphic multivalent functions is defined by means of a q-difference operator. Some properties of the functions in this new subclass, such as sufficient and necessary conditions, coefficient estimates, growth and distortion theorems, radius of starlikeness and convexity, partial sums and closure theorems, are investigated.

Perfect colorings of patterns with multiple orbits

2019 ◽  
Vol 75 (6) ◽  
pp. 814-826
Author(s):  
Allan Junio ◽  
Ma. Lailani Walo
Keyword(s):  
Necessary Conditions ◽  
Sufficient And Necessary Conditions

This paper studies colorings of patterns with multiple orbits, particularly those colorings where the orbits share colors. The main problem is determining when such colorings become perfect. This problem is attacked by characterizing all perfect colorings of patterns through the construction of sufficient and necessary conditions for a coloring to be perfect. These results are then applied on symmetrical objects to construct both perfect and non-perfect colorings.

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