Mechanistic Model for Spade Drills for Wood Drilling Operations, Part 2: Analysis of Spade Bit Geometry and Performance

2003 ◽  
Vol 125 (2) ◽  
pp. 236-244 ◽  
Author(s):  
Hanxin Zhao ◽  
Kornel F. Ehmann
Keyword(s):  
Performance Measures ◽  
Thrust Force ◽  
Simulation Analysis ◽  
Mechanistic Model ◽  
Geometric Model ◽  
Analytical Models ◽  
Force System ◽  
Topological Features ◽  
Drilling Operations ◽  
And Performance

In this part of the paper the analytical models for the prediction of the force system, established in Part 1, in conjunction with a complete geometric model of the spade bit, will be used in a systematic simulation analysis of the spade drill’s performance. The aim of this analysis is to identify the most desirable geometric characteristics of the different topological features of the spade bit that would result in desirable performance measures expressed in terms of reduced torque and thrust force. The obtained results are intended to guide the development of more efficient tools of this type.

Mechanistic Model for Spade Drills for Wood Drilling Operations, Part 1: Model Development

2003 ◽  
Vol 125 (2) ◽  
pp. 226-235 ◽  
Author(s):  
Hanxin Zhao ◽  
Kornel F. Ehmann
Keyword(s):  
Model Calibration ◽  
Prediction Models ◽  
Mechanistic Model ◽  
Model Development ◽  
Calibration Method ◽  
Technical Literature ◽  
Force System ◽  
Force Prediction ◽  
Drilling Operations ◽  
Improved Performance

The purpose of this work is to present an investigation of the force system generated during spade drill-bit drilling processes that is a prerequisite for the design of spade-drills with improved performance. The technical literature offers no references to this type of bit and process; hence an approach based on the well-established mechanistic force prediction methods will be used. The force and torque prediction models are based on a complete analytical model of a generalized spade bit that takes into account the cutting action of all the characteristic cutting edges of the spade bit, namely of its chisel edge, tip and major cutting edges. In conjunction with the model an efficient model calibration method is also introduced and experimentally verified.

Cognitive and affective benefits of colouring: Two randomized controlled crossover studies

2018 ◽  
Author(s):  
Nicola Jane Holt ◽  
Leah Furbert ◽  
Emily Sweetingham
Keyword(s):  
Selective Attention ◽  
Performance Measures ◽  
Divergent Thinking ◽  
Attention Task ◽  
Creative Cognition ◽  
Randomized Controlled ◽  
Mindful Attention ◽  
Crossover Studies ◽  
And Performance ◽  
Implicit Mood

The current research sought to replicate and extend work suggesting that coloring can reduce anxiety, asking whether coloring can improve cognitive performance. In two experiments undergraduates (N = 47; N = 52) colored and participated in a control condition. Subjective and performance measures of mood and mindfulness were included: an implicit mood test (Experiment 1) and a selective attention task (Experiment 2) along with a divergent thinking test. In both experiments coloring significantly reduced anxiety and increased mindfulness compared with control and baseline scores. Following coloring participants scored significantly lower on implicit fear, than the control condition, and significantly higher on selective attention and original ideation. Coloring may not only reduce anxiety, but also improve mindful attention and creative cognition.

Determinants of Control System Design in Divisionalized Firms

2004 ◽  
Vol 79 (3) ◽  
pp. 545-570 ◽  
Author(s):  
Margaret A. Abernethy ◽  
Jan Bouwens ◽  
Laurence van Lent
Keyword(s):  
Control System ◽  
System Design ◽  
Performance Measures ◽  
Simultaneous Equation ◽  
Equation Model ◽  
Control System Design ◽  
Information Asymmetries ◽  
Endogenous Variables ◽  
And Performance ◽  
Using Data

We investigate two determinants of two choices in the control system of divisionalized firms, namely decentralization and use of performance measures. The two determinants are those identified in the literature as important to control system design: (1) information asymmetries between corporate and divisional managers and (2) division interdependencies. We treat decentralization and performance measurement choices as endogenous variables and examine the interrelation among these choices using a simultaneous equation model. Using data from 78 divisions, our results indicate that decentralization is positively related to the level of information asymmetries and negatively to intrafirm interdependencies, while the use of performance measures is affected by the level of interdependencies among divisions within the firm, but not by information asymmetries. We find some evidence that decentralization choice and use of performance measures are complementary.

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