Tip potential of open-tip glass microelectrodes: theoretical and experimental studies

1983 ◽  
Vol 61 (8) ◽  
pp. 857-869 ◽  
Author(s):  
Simon Gagné ◽  
Réjean Plamondon
Keyword(s):  
Theoretical Model ◽  
Theoretical Analysis ◽  
Mathematical Analysis ◽  
Experimental Studies ◽  
Graphical Analysis ◽  
Double Layers ◽  
Glass Layer ◽  
Mathematical Expressions ◽  
Tip Potential ◽  
Bulk Solutions

A mathematical analysis of the tip potential based on the main physicochemical phenomena occurring at the tip of a glass microelectrode is presented. The factors considered in the theoretical analysis are the diffusion of ions through the open tip, the conduction in the bulk solutions, the longitudinal conduction in the double layers at the glass-electrolyte interfaces, and to some extent, in a hydrated glass layer. A graphical analysis of the mathematical expressions as a function of the resistivity of test solutions is done and the distribution of the source potentials giving rise to the tip potential is studied. The experimental results presented in the paper confirm the validity of the proposed theoretical model. Comments for an improved use of glass microelectrodes in electrophysiological experiments are given throughout the paper.

scholarly journals A Framework for Modelling Economic Regional Location Processes Under Uncertainty

2021 ◽  
Author(s):  
Roy Cerqueti ◽  
Eleonora Cutrini
Keyword(s):  
Theoretical Model ◽  
Theoretical Analysis ◽  
Site Selection ◽  
Decision Problem ◽  
Stochastic Theory ◽  
Spatial Location ◽  
Probabilistic Framework ◽  
Location Patterns ◽  
Regional Location ◽  
Quantitative Tool

AbstractThis paper deals with the theoretical analysis of the spatial concentration and localization of firms and employees over a set of regions. In particular, it provides a simple site-selection theoretical model to describe the probabilistic framework of the location patterns. The adopted quantitative tool is the stochastic theory of urns. The model moves from the empirical evidence of the deviation of the spatial location of companies from the uniform distribution and of employees from the distribution of firms. Factors leading to such deviations are taken into consideration. Specifically, we formalize a decision problem grounded on the economic attributes of the regions and also on the distribution of the existing firms and employees in the territory. To our purpose, the site-selection model is presented as a stepwise process.

scholarly journals Analysis of a Cantilevered Piezoelectric Energy Harvester in Different Orientations for Rotational Motion

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1206 ◽  
Author(s):  
Wei-Jiun Su ◽  
Jia-Han Lin ◽  
Wei-Chang Li
Keyword(s):  
Theoretical Model ◽  
Resonant Frequency ◽  
Rotational Motion ◽  
Axial Load ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Experimental Studies ◽  
Piezoelectric Energy ◽  
Piezoelectric Cantilever ◽  
Tip Mass

This paper investigates a piezoelectric energy harvester that consists of a piezoelectric cantilever and a tip mass for horizontal rotational motion. Rotational motion results in centrifugal force, which causes the axial load on the beam and alters the resonant frequency of the system. The piezoelectric energy harvester is installed on a rotational hub in three orientations—inward, outward, and tilted configurations—to examine their influence on the performance of the harvester. The theoretical model of the piezoelectric energy harvester is developed to explain the dynamics of the system and experiments are conducted to validate the model. Theoretical and experimental studies are presented with various tilt angles and distances between the harvester and the rotating center. The results show that the installation distance and the tilt angle can be used to adjust the resonant frequency of the system to match the excitation frequency.

Dynamic Characterization of a Valveless Micropump Considering Entrapped Gas Bubbles

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Songjing Li ◽  
Jixiao Liu ◽  
Dan Jiang
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Experimental Studies ◽  
Gas Bubbles ◽  
Chamber Pressure ◽  
Dynamic Characterization ◽  
Valveless Micropump ◽  
Performance Deterioration ◽  
Trapped Gas

Unexpected gas bubbles in microfluidic devices always bring the problems of clogging, performance deterioration, and even device functional failure. For this reason, the aim of this paper is to study the characterization variation of a valveless micropump under different existence conditions of gas bubbles based on a theoretical modeling, numerical simulation, and experiment. In the theoretical model, we couple the vibration of piezoelectric diaphragm, the pressure drop of the nozzle/diffuser and the compressibility of working liquid when gas bubbles are entrapped. To validate the theoretical model, numerical simulation and experimental studies are carried out to investigate the variation of the pump chamber pressure influenced by the gas bubbles. Based on the numerical simulation and the experimental data, the outlet flow rates of the micropump with different size of trapped gas bubbles are calculated and compared, which suggests the influence of the gas bubbles on the dynamic characterization of the valveless micropump.

scholarly journals Theoretical and experimental studies of a gas stamping device with a piston pressure multiplier

2019 ◽  
Vol 18 (1) ◽  
pp. 163-173
Author(s):  
A. Yu. Botashev ◽  
R. A. Bayramukov
Keyword(s):  
Theoretical Analysis ◽  
Experimental Studies ◽  
Fuel Mixture ◽  
Small Scale ◽  
Scale Production ◽  
Pressure Treatment ◽  
Energy Of Combustion ◽  
Stamping Process ◽  
Pressure Multiplier ◽  
The Matrix

In many industries, the share of small-scale production plants is significant. In these conditions, compared with traditional methods of pressure treatment, pulse pressure treatment methods, one of the varieties of which is gas stamping, are more efficient. However, the known devices of gas stamping provide mainly stamping of thin-walled parts. To expand the technological capabilities of gas stamping, the authors developed a gas stamping device with a piston pressure multiplier, in which heating and deformation of the stamping workpiece is carried out using the energy of combustion of fuel mixtures in the combustion chamber, in the working cylinder and in the cavity of the matrix. This article is devoted to the study of the workflow of this device. Theoretical analysis of the workflow was carried out, and, as a result, a pattern was determined for the variation of the pressure that performs the stamping process in the working cylinder. In particular, it was found that at the final stage of the stamping process, due to the energy of combustion of the fuel mixture, the pressure in the working cylinder increases 1.5...2 times, which allows a significant increase in the thickness of the parts to be stamped. An experimental gas stamping device with a piston pressure multiplier was developed, and experimental studies were carried out. The studies confirmed the main results of the theoretical analysis: the discrepancy between the theoretical and experimental values of the degree of pressure multiplication in the working cylinder does not exceed 11%.

scholarly journals Theoretical analysis of legislative definition of the regime in correctional institutions: problems and ways to solve them

2021 ◽  
Vol 7 (1) ◽  
pp. 70-75
Author(s):  
V. E. Juzhanin ◽  
D. V. Gorban'
Keyword(s):  
Theoretical Model ◽  
Theoretical Analysis ◽  
Russian Federation ◽  
Criminal Code ◽  
Penal System ◽  
Correctional Institutions ◽  
Scientific Thought ◽  
General Part ◽  
The Russian Federation ◽  
Definition Of

The article provides a theoretical analysis of Part 1 of Article 82 of the Criminal Code of the Russian Federation, which defines the regime in correctional institutions of the Russian penal system. It is noted that this definition does not correspond to the achievements of modern penitentiary scientific thought about the regime. In particular, it is emphasized that the regime cannot provide conditions for serving a sentence, since it includes these conditions. Also, the regime cannot ensure the protection of convicts, supervision over them and separate maintenance of different categories of convicts, since, on the contrary, the latter are the means of ensuring the regime. According to the authors of the article, the legislator incorrectly uses the phrase regime of detention of convicts, meaning regime of serving a sentence, since they are different legal phenomena. It is noted that the most optimal definition of the regime is presented in the theoretical model of the general part of the new Criminal Code of the Russian Federation, prepared by a group of authors, but the authors also subjected this definition to some adjustments.

How to create a human communication system

2017 ◽  
Vol 18 (3) ◽  
pp. 314-329 ◽  
Author(s):  
Casey J. Lister ◽  
Nicolas Fay
Keyword(s):  
Theoretical Model ◽  
Communication System ◽  
Communication Systems ◽  
Experimental Studies ◽  
Human Communication ◽  
Content Type ◽  
Sign Systems ◽  
The Creation ◽  
Interactive Feedback ◽  
Single Modality

Following a synthesis of naturalistic and experimental studies of language creation, we propose a theoretical model that describes the process through which human communication systems might arise and evolve. Three key processes are proposed that give rise to effective, efficient and shared human communication systems: (1) motivated signs that directly resemble their meaning facilitate cognitive alignment, improving communication success; (2) behavioral alignment onto an inventory of shared sign-to-meaning mappings bolsters cognitive alignment between interacting partners; (3) sign refinement, through interactive feedback, enhances the efficiency of the evolving communication system. By integrating the findings across a range of diverse studies, we propose a theoretical model of the process through which the earliest human communication systems might have arisen and evolved. Importantly, because our model is not bound to a single modality it can describe the creation of shared sign systems across a range of contexts, informing theories of language creation and evolution.

Theoretical and Methodological Model of the Influence of Mindfulness Practices on the Teacher’s Personality

2020 ◽  
Vol 6 (2) ◽  
pp. 67-73
Author(s):  
Olha P. Shevchuk ◽  
Natalia P. Yaroshchuk
Keyword(s):  
Academic Success ◽  
Theoretical Model ◽  
Theoretical Analysis ◽  
Well Being ◽  
Educational Process ◽  
The Body ◽  
Subjective Feeling ◽  
Emotional States ◽  
Mindfulness Practices

The relevance of the study lies in covering the potential of meditative practices in the educational process. The purpose of the study is to carry out a theoretical analysis and outline the probable forms of integration of mindfulness practices into the educational process on the example of teachers, as well as to create a theoretical model of the influence of mindfulness practices on the teacher’s personality with professional destruction. The study highlights the main theoretical models of understanding mindfulness practices. The most effective and most frequently used techniques of awareness practice are analysed. The main educational centres of mindfulness in Ukraine are highlighted. Theoretical analysis of empirical research of foreign colleagues in the field of positive influence of mindfulness practices on the personality is carried out. The causes of professional destruction of teachers are analysed. The expediency and efficiency of this integration are argued. Among the positive changes due to the use of awareness practices by teachers are: improving the level of concentration and recollection; increasing attention to the needs and emotional states of students; creating emotional balance and preventing burnout; increasing the level of stress resistance; improving the quality of relationships at work and at home; increasing productivity and as a result of academic success; forming openness and readiness for selfdevelopment; development of the level of reflection and skills to regulate one’s emotions; improving the psychological climate in the classroom and maintaining overall psychological well-being; improving the quality of life and increasing the subjective feeling of happiness. The scientific novelty lies in the creation and operationalisation of a theoretical model of the influence of mindfulness practices on the teacher’s personality with professional destruction through the lens of cognitive, emotional, physiological, and behavioural levels. It is established that the practice of awareness is the main skill of presence in everything that happens to us, around and inside, in the body, feelings and thoughts

Model of geometrical and smooth muscle tone adaptation of carotid artery subject to step change in pressure

2001 ◽  
Vol 280 (6) ◽  
pp. H2752-H2760 ◽  
Author(s):  
P. Fridez ◽  
A. Rachev ◽  
J.-J. Meister ◽  
K. Hayashi ◽  
N. Stergiopulos
Keyword(s):  
Experimental Data ◽  
Smooth Muscle ◽  
Theoretical Model ◽  
Arterial Wall ◽  
Circumferential Stress ◽  
Experimental Studies ◽  
Synthetic Activity ◽  
Wall Thickening ◽  
Model Parameters ◽  
Induced Hypertension

Recent experimental studies have shown significant alterations of the vascular smooth muscle (VSM) tone when an artery is subjected to an elevation in pressure. Therefore, the VSM participates in the adaptation process not only by means of its synthetic activity (fibronectins and collagen) or proliferative activity (hypertrophy and hyperplasia) but also by adjusting its contractile properties and its tone level. In previous theoretical models describing the time evolution of the arterial wall adaptation in response to induced hypertension, the contribution of VSM tone has been neglected. In this study, we propose a new biomechanical model for the wall adaptation to induced hypertension, including changes in VSM tone. On the basis of Hill's model, total circumferential stress is separated into its passive and active components, the active part being the stress developed by the VSM. Adaptation rate equations describe the geometrical adaptation (wall thickening) and the adaptation of active stress (VSM tone). The evolution curves that are derived from the theoretical model fit well the experimental data describing the adaptation of the rat common carotid subjected to a step increase in pressure. This leads to the identification of the model parameters and time constants by characterizing the rapidity of the adaptation processes. The agreement between the results of this simple theoretical model and the experimental data suggests that the theoretical approach used here may appropriately account for the biomechanics underlying the arterial wall adaptation.

scholarly journals Modeling Planar Fluxgate Structures

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 830
Author(s):  
Michael Ortner ◽  
Neosha Navaei ◽  
Martin Lenzhofer
Keyword(s):  
Theoretical Model ◽  
Experimental Studies ◽  
Direct Coupling ◽  
Fem Simulations ◽  
3D Structures ◽  
Classical Models ◽  
Planar Systems ◽  
The Stability ◽  
Magnetostatic Simulation

Planar fluxgate structures have been the focus of multiple experimental studies. However, theoretical treatises are still limited to the classical models that describe 3D structures. In this paper we derive an effective fluxgate equation for planar systems, dealing with strong stray fields and direct coupling, and show the stability and applicability of the Vacquier implementation. To support the theoretical model, FEM simulations are performed that also provide means of layouting planar fluxgates by pure magnetostatic simulation.

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