scholarly journals Variable Stiffness Mechanism for the Reduction of Cutting Forces in Robotic Deburring

2021 ◽  
Vol 11 (6) ◽  
pp. 2883
Author(s):  
Matteo Bottin ◽  
Silvio Cocuzza ◽  
Matteo Massaro
Keyword(s):  
Conceptual Design ◽  
Cutting Forces ◽  
Variable Stiffness ◽  
Optimization Method ◽  
The Other ◽  
Design Parameters ◽  
Test Cases ◽  
Dynamic Simulations ◽  
Main Design ◽  
The One

One of the main issues related to robotic deburring is that the tool can get damaged or stopped when the burr thickness exceeds a certain threshold. The aim of this work is to devise a mechanism that can reduce cutting forces automatically, in the event that the burr is too high, and is able to return to the baseline configuration when the burr thickness is acceptable again. On the one hand, in normal cutting conditions, the mechanism should have high stiffness to ensure high cutting precision. On the other hand, when the burr is too high the mechanism should exploit its compliance to reduce the cutting forces and, as a consequence, a second cutting cycle will be necessary to completely remove the burr. After the conceptual design of the mechanism and the specification of the desired stiffness curve, the main design parameters of the system are derived thanks to an optimization method. The effectiveness of the proposed mechanism is verified by means of dynamic simulations using selected test cases. A reduction up to 60% of the cutting forces is obtained, considering a steel burr up to 6 mm high.

Comparison of Partial vs Full Admission for Small Turbines at Low Specific Speeds

1985 ◽  
Author(s):  
Ennio Macchi ◽  
Giovanni Lozza
Keyword(s):  
Axial Flow ◽  
Design Procedure ◽  
Optimization Method ◽  
Expansion Ratio ◽  
Operating Conditions ◽  
Design Parameters ◽  
Basic Design ◽  
Partial Admission ◽  
Specific Speed ◽  
The One

Several methods are available for the optimization of basic design parameters and the preliminary efficiency prediction of axial flow turbine stages. However, their application is often questionable for stages having low specific speed and/or small volume flow rates. In particular, the question may arise whether a better performance is achieved by a partial admission, impulse stage or by a full admission reaction stage having lower blade height. The paper firstly reviews the available loss correlation methods applicable to partial admission turbines, then a comparison is performed between the efficiency achievable by partial and full admission stages designed for the same operating conditions. The turbine design procedure for both options is fully automatized by an efficiency optimization method similar to the one described in previous authors’ papers. The results of calculations are presented in the paper as a function of similarity parameters (specific speed, size parameter, expansion ratio). It is found that the results obtained with different correlations are relatively similar for “conventional” turbine stages (low expansion ratio, moderate size parameters), while important differences take place for very small sizes and/or in presence of important compressibility effects. The presented results can be useful: 1) to decide whether selecting full or partial admission solutions; 2) to optimize the degree of admission and the other basic design parameters, and 3) to predict with reasonable accuracy the stage efficiency.

HOW CAN WE STOP THE SEWAGE?

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
J. M. Sáez ◽  
M. J. M. Davis ◽  
M. L. Gutiérrez ◽  
A. Vallejo ◽  
L. Ayala
Keyword(s):  
Urban Areas ◽  
Social Acceptance ◽  
Optimal Solution ◽  
End Users ◽  
The Other ◽  
Design Parameters ◽  
Second Phase ◽  
Sociological Research ◽  
Black Water ◽  
The One

In Ecuador 46.4% of households lack access to sewerage systems, and then much wastewater is discharged from sewerage into the environment untreated. On the one hand dry toilet systems present themselves as an optimal solution against this backdrop; they mitigate the production of black water, whilst having fertilizer as the end product. On the other hand, they tend to have a low acceptance level by potential end users. This problem of social acceptance is then further exacerbated in urban areas. In order to overcome this, the design of an ecological dry/semi-dry toilet was carried out in two phases. The first phase consisted of purely sociological research, where the aim was to determine the basic design parameters that should be used for ecological toilet prototype. The second phase is the development of ecological toilet prototypes, which are then tested in terms of their level of acceptance/rejection by potential end users. The overall aim is to develop toilet prototypes that on the one hand mitigate the production of black water, whilst on the other are accepted with open arms by end users, and even preferred over the conventional toilet common to urban areas.

scholarly journals Evolution of COVID-19 Disease Using a One Prey-Two Predator Mode

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Amila Sudu Ambegedara ◽  
Asini A. Konpola ◽  
Chathurika S. Gunasekara ◽  
Indika G. Udagedara
Keyword(s):  
Equilibrium Point ◽  
Disease Transmission ◽  
Equilibrium Points ◽  
Optimization Method ◽  
The Other ◽  
Population Declines ◽  
Data Set ◽  
Uniqueness Of The Solution ◽  
Predator Model ◽  
The One

Mathematical modeling is used to understand the dynamics of transmission of infectious diseases such as COVID-19, SARS, Ebola, and Dengue among populations. In this work, a one prey-two predator model has been developed to understand the underlying dynamics of COVID-19 disease transmission. We considered the infected, recovered, and death populations with the fact that an infected person can be transformed into the recovered or death group assuming that the infected ones are the prey, and the other two populations are the two predators in the one prey-two predator model. It was found that the proposed model has four equilibrium points; the vanishing equilibrium point ( ), recovered and death-free equilibrium point ( ), recovered population-free equilibrium point ( ), and the death-free equilibrium point ( ). Stability analysis of the equilibrium points shows that except all the other equilibrium points are locally asymptotically stable. Global asymptotic stability of the recovered population-free equilibrium point and death-free equilibrium point are also analyzed. Moreover, the existence and uniqueness of the solution were proved. The parameters for the model are estimated from a data set that consists of the total number of infected, recovered, and dead populations worldwide in the year 2020 using the Nelder-Mead optimization method. When the time approaches infinity, the infected population converges to a constant value, the recovered population declines and reaches zero, and the death population attains a constant value. However, some modifications to the system are needed. In future work, measures such as health precautions, vaccinations are needed to be considered for the formulation of the mathematical model.

scholarly journals Educación Abierta y Enseñanza de la Traducción a Través de Cursos MOOC de España y del Reino Unido: Análisis Comparativo

2018 ◽  
Vol 5 (1) ◽  
pp. 83-113
Author(s):  
Bianca Vitalaru ◽  
Laura María Rodríguez Galán
Keyword(s):  
The Other ◽  
Design Strategies ◽  
Main Design ◽  
The United Kingdom ◽  
Level Of Satisfaction ◽  
Different Types ◽  
The Subject ◽  
The One ◽  
General Aspects ◽  
Gathering Data

Resumen: Este artículo tiene dos objetivos principales. Por un lado, se centrará en presentar cuatro cursos MOOC del campo de la traducción en España y en el Reino Unido y analizar diferentes aspectos relacionados con su diseño y estructura. Cabe señalar que, según nuestra investigación, los cursos seleccionados parecen ser más representativos en cuanto a la temática (la traducción en general y la TISP en particular) y a la combinación lingüística (español-inglés) que nos interesa. Específicamente, se compararán diferentes tipos de elementos, desde aspectos más generales relacionados con su creación (como la plataforma en la que se alojan, el acceso, los idiomas en los que se imparte, la duración o las posibilidades de obtención de certificado) hasta aspectos más específicos como los objetivos, la estructura, el temario y diferentes estrategias de diseño. Por otro lado, también se destacarán los principales aspectos de diseño que afectan a su estructura como el número de bloques teóricos, vídeos teóricos, actividades prácticas y autoevaluaciones, así como las posibilidades de recogida de datos y evaluación del nivel de satisfacción de los usuarios. Finalmente, del análisis comparativo de los cursos se extraerán conclusiones y nuestras propias reflexiones sobre la aplicabilidad de lo que consideraremos como diferentes estrategias utilizadas por los autores en el diseño de MOOCs en el campo de la traducción. Todos estos aspectos pueden ser de utilidad para la elaboración de futuros MOOC sobre traducción más específicos, por ejemplo, en el campo de la TISP en España, en el que, según las investigaciones del grupo FITISPos, la oferta formativa sigue siendo muy escasa.Abstract: This article has two main objectives. On the one hand, it will focus on presenting four MOOC courses in the field of translation in Spain and in the United Kingdom and on analyzing different aspects related to their design and structure. It should be noted that, according to our research, the selected courses seem to be more representative in terms of the subject (translation in general and PSIT in particular) and in terms of the linguistic combination (Spanish-English) that we are interested in. Specifically, different types of elements will be compared, from more general aspects related to their creation (such as the platform where they have been uploaded, the access, the languages in which it is taught, the duration and the possibilities of obtaining a certificate of completion) to more specific aspects such as the objectives, the structure, the topics and different design strategies. On the other hand, the main design aspects that affect its structure, such as the number of theoretical blocks, videos, activities and self-evaluations, as well as the possibilities of gathering data on the users’ profile and evaluating their level of satisfaction, will also be highlighted. Finally, the comparative analysis of the courses will allow us to draw conclusions and our own reflections on the applicability of what we considered as different strategies used by the authors in the design of MOOCs in the field of translation. These aspects may be useful for the development of future MOOCs on more specialized translation, for example, in the field of the PSIT in Spain, in which, according to the research of the FITISPos-UAH group, the training offer is still very scarce.

scholarly journals Design Criteria and Efficiency Prediction for Radial Inflow Turbines

1987 ◽  
Author(s):  
Antonio Perdichizzi ◽  
Giovanni Lozza
Keyword(s):  
Computer Code ◽  
Expansion Ratio ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Test Cases ◽  
Main Design ◽  
Turbine Efficiency ◽  
Design Variables ◽  
Specific Speed ◽  
Turbine Design

A theoretical investigation was performed to predict the maximum achievable efficiency of radial inflow turbines for different design conditions. The analytical tool used in the investigation is a computer code able to perform the contemporary optimization of the main design variables, in order to obtain maximum efficiency. Since the results are strictly dependent on the loss correlations, reliability of the efficiency predictions was tested at first by comparison with several test-cases available in literature: good agreement with experimental data was found, pointing to the validity of the results presented here. A large number of cases were analyzed: the efficiency and the main design parameters, obtained after the optimization process, are presented for optimum specific speed. Turbine efficiency was found to be dependent both on compressibility effects, related to the volume expansion ratio, and on actual turbine size, accounting for geometric non-similarity effects. Influence of non-optimum specific speed is also discussed. By means of similarity rules, the results enable turbine design to be performed in a simple way, for a variety of working fluids and design conditions.

Design optimization of rotor-bearing system considering critical speed using Taguchi method

2016 ◽  
Vol 231 (2) ◽  
pp. 138-146 ◽  
Author(s):  
Emre Yücel ◽  
Hamit Saruhan
Keyword(s):  
Taguchi Method ◽  
Critical Speed ◽  
Optimization Method ◽  
Design Parameters ◽  
Test Case ◽  
Test Cases ◽  
Shaft System ◽  
Rotor Bearing ◽  
Vibration Signatures ◽  
Bearing System

The purpose of this study is to utilize Taguchi method, which can prove to be a handy and effective tool for determining minimum vibration response of rotor-bearing system set to avoid running at critical speed. In the study, three test cases considering different coupling type (elastic, jaw, and solid) and disc location (disc location A, B, and C) were conducted to observe behavioral changes of the shaft system considering vibration signatures. Each test case was conducted for three different shaft running speeds of 12, 18, and 24 Hz. To find the minimum peak amplitude values by experimenting different combinations of the rotor-bearing system set needs a lot of experiments for reaching solution. Moreover, the solution proves costly because of the time consumed in doing many experiments. This fact depicts the importance of an efficient optimization method to be used. Taguchi method can determine the design parameters, which have the greatest influence on the solution through a very limited number of experiments, for finding optimum set of rotor-bearing system. The method is performed using an iterative procedure to gain an optimum design.

Design Parameters for a Two-State Nanomemory Device

2011 ◽  
Vol 700 ◽  
pp. 85-88 ◽  
Author(s):  
Richard K. F. Lee ◽  
James M. Hill
Keyword(s):  
Energy Barrier ◽  
Minimum Energy ◽  
Memory Device ◽  
The Other ◽  
Design Parameters ◽  
Continuum Approximation ◽  
Information State ◽  
Lennard Jones ◽  
The One ◽  
The Continuum

In this study, we investigate the internal mechanics for a two-state memory device,comprising a charged metallofullerene which is located inside a closed carbon nanotube.Assuming the Lennard-Jones interaction energy and the continuum approximation, the metallofullerenehas two symmetrically placed equal minimum energy positions. On one side theencapsulated metallofullerene represents the zero information state and by applying an externalelectrical field, the metallofullerene can be made to overcome the energy barrier of thenanotube, and pass from one end of the tube to the other, where the metallofullerene thenrepresents the one information state.

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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