Creating internal conductivity in dry biological SEM samples by a simple vapour treatment

2014 ◽  
Vol 256 (3) ◽  
pp. 226-230 ◽  
Author(s):  
H.-J. ENSIKAT ◽  
M. WEIGEND
Keyword(s):  
Internal Conductivity

scholarly journals The influence of air movement and atmospheric conditions on the heat loss from a cylindrical moist body

1939 ◽  
Vol 39 (1) ◽  
pp. 60-89 ◽  
Author(s):  
Alan J. Canny ◽  
C. J. Martin
Keyword(s):  
Heat Exchange ◽  
Heat Loss ◽  
Wind Velocity ◽  
Effective Temperature ◽  
Physical System ◽  
Square Root ◽  
Atmospheric Conditions ◽  
Internal Temperature ◽  
Air Movement ◽  
Internal Conductivity

It is emphasized that as heat exchange is controlled by the temperature of that boundary layer of molecular dimensions which separates a cooling body from its environment and from which evaporation occurs, attempts to relate heat loss with internal temperature have resulted only in empirical formulae. A rational formula involving the temperature of the evaporating surface is suggested, and it is shown how in the case of a system of sufficient simplicity all the terms can be either measured or derived from experiments.The results of experiments with a small moistened cylinder are detailed illustrating the effect of wind velocity upon evaporative and convective heat loss under the one condition when the evaporating surface remains at constant temperature notwithstanding variations in wind, namely, when the whole system has been cooled to wet-bulb temperature. Evaporative loss is found to vary as V0.65, convective as V0.70.Experiments are next described showing the effect of wind upon evaporative and convective losses when, the internal temperature being constant, the temperature of the evaporating surface fluctuates in consequence of varying wind velocity. Heat loss now varies very closely as V0.5 at velocities greater than 1 m./sec. At velocities below 1 m./sec. the same relation of heat loss to velocity obtains if due allowance be made for natural convection. This square root function is fortuitous, and heat loss varied between the square root and cube root of the velocity as the internal conductivity was diminished.Attention is drawn to the impossibility of forming general conclusions from observations on any particular system, as the way in which the rate of heat loss varies with the velocity of the wind depends not only upon the internal conductivity of the system but also on its size and shape.Observations are described showing the influence of varying the internal temperature on total and evaporative heat loss with constant wind velocity and constant atmospheric conditions. These experiments furnish data from which the surface temperature can be derived from measurements of evaporation, and show that the temperature of the surface and the rate of loss of heat by convection are both linear functions of the internal temperature at any one wind velocity. They also show that the values of the constants of the system derived from experiments at the temperature of the wet bulb are applicable when the cylinder is heated.An analysis of the results of the experiments with varying internal temperature indicates that the temperature of the evaporating surface (ts) is related to the internal temperature (t1) and that of the wet bulb (tw) by the expression The value of C with varying wind velocity is ascertained by experiments, thus affording another means of arriving at the temperature of the evaporating layer. Values of ts obtained in this way are compared with those determined by observing the rate of evaporation and show reasonable agreement.It is shown how, knowing the temperature of the evaporating layer, the constants of the system employed and the effect of velocity of wind upon heat exchange, the rate of loss of heat by evaporation and by convection under given conditions can be predicted. Instances of the agreement between predicted and observed values are given.From the formula representing the influence of atmospheric conditions on heat loss it can be shown, by calculation, that if the wet-bulb temperature remains constant considerable variations in the temperature of the dry-bulb influence but slightly the heat loss from the moist cylinder.It will be seen that the analysis of the effects of environmental changes on the heat loss from a simple physical system such as was used presents no serious difficulties. Such an analysis, unfortunately, does not enable deductions to be made with reference to systems of different physical characteristics. How observations on such systems can be related in other than a qualitative manner to the effects of corresponding changes on living creature differing in size and shape and degree of moistening of their surfaces is not clear. When account is taken of the ability of living beings to alter the vascularity of their surface tissues and so to vary the temperature of the body surface while other factors remain constant, the difficulties in relating the cooling of any physical system to the loss of heat from animals become painfully apparent.The most hopeful method of assessing the effect of air movement and atmospheric conditions on the heat loss from the human body seems to be in terms of a subjectively determined standard such as the effective temperature scale of Houghton & Yaglou. The validity of such a scale has received support from observations by Houghton et al. (1924) and Vernon & Warner (1932) on the relation of pulse rate, body temperature, metabolism and other physiological variables to “effective temperature”.

scholarly journals Magnetic induction pneumography: a planar coil system for continuous monitoring of lung function via contactless measurements

2019 ◽  
Vol 1 (1) ◽  
pp. 56-62 ◽  
Author(s):  
Doğa Gürsoy ◽  
Hermann Scharfetter
Keyword(s):  
Lung Function ◽  
Magnetic Induction ◽  
Continuous Monitoring ◽  
Patient Comfort ◽  
Point Spread Functions ◽  
Mechanically Ventilated ◽  
Planar Coil ◽  
Residual Norm ◽  
Imaging Artifacts ◽  
Internal Conductivity

Abstract Continuous monitoring of lung function is of particular interest to the mechanically ventilated patients during critical care. Recent studies have shown that magnetic induction measurements with single coils provide signals which are correlated with the lung dynamics and this idea is extended here by using a 5 by 5 planar coil matrix for data acquisition in order to image the regional thoracic conductivity changes. The coil matrix can easily be mounted onto the patient bed, and thus, the problems faced in methods that use contacting sensors can readily be eliminated and the patient comfort can be improved. In the proposed technique, the data are acquired by successively exciting each coil in order to induce an eddy-current density within the dorsal tissues and measuring the corresponding response magnetic field strength by the remaining coils. The recorded set of data is then used to reconstruct the internal conductivity distribution by means of algorithms that minimize the residual norm between the estimated and measured data. To investigate the feasibility of the technique, the sensitivity maps and the point spread functions at different locations and depths were studied. To simulate a realistic scenario, a chest model was generated by segmenting the tissue boundaries from NMR images. The reconstructions of the ventilation distribution and the development of an edematous lung injury were presented. The imaging artifacts caused by either the incorrect positioning of the patient or the expansion of the chest wall due to breathing were illustrated by simulations.

Internal Conductivity of Axons, Nerve Cell Bodies and Large Nonnervous Cells

1975 ◽  
Author(s):  
D. O. Carpenter ◽  
M. M. Hovey ◽  
A. F. Bak
Keyword(s):  
Nerve Cell ◽  
Internal Conductivity

scholarly journals A Krylov subspace type method for Electrical Impedance Tomography

2021 ◽  
Author(s):  
Mirjeta Pasha ◽  
Shyla Kupis ◽  
Sanwar Ahmad ◽  
Taufiquar Khan
Keyword(s):  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Krylov Subspace ◽  
Low Frequency ◽  
Small Dimension ◽  
Impedance Tomography ◽  
Type Method ◽  
Newton Algorithm ◽  
Ill Posed ◽  
Internal Conductivity

Electrical Impedance Tomography (EIT) is a well-known imaging technique for detecting the electrical properties of an object in order to detect anomalies, such as conductive or resistive targets. More specifically, EIT has many applications in medical imaging for the detection and location of bodily tumors since it is an affordable and non-invasive method, which aims to recover the internal conductivity of a body using voltage measurements resulting from applying low frequency current at electrodes placed at its surface. Mathematically, the reconstruction of the internal conductivity is a severely ill-posed inverse problem and yields a poor quality image reconstruction. To remedy this difficulty, at least in  part, we regularize and solve the nonlinear minimization problem by the aid of a Krylov subspace-type method for the linear sub problem during each iteration.  In EIT, a tumor or general anomaly can be modeled as a piecewise constant perturbation of a smooth background, hence, we solve the regularized problem on a subspace of relatively small dimension by the Flexible Golub-Kahan process that provides solutions that have sparse representation. For comparison, we use a well-known modified Gauss-Newton algorithm as a benchmark. Using simulations, we demonstrate the effectiveness of the proposed method. The obtained reconstructions indicate that the Krylov subspace method is better adapted to solve the ill-posed EIT problem and results in higher resolution images and faster convergence compared to reconstructions using the modified Gauss-Newton algorithm.

A novel deep neural network method for electrical impedance tomography

2019 ◽  
Vol 41 (14) ◽  
pp. 4035-4049 ◽  
Author(s):  
Xiuyan Li ◽  
Yong Zhou ◽  
Jianming Wang ◽  
Qi Wang ◽  
Yang Lu ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Simulation Software ◽  
Voltage Measurement ◽  
Finite Elements Analysis ◽  
Impedance Tomography ◽  
Conductivity Distribution ◽  
Highly Nonlinear ◽  
Internal Conductivity

Image reconstruction for Electrical Impedance Tomography (EIT) is a highly nonlinear and ill-posed inverse problem. It requires the design and employment of feasible reconstruction methods capable to guarantee trustworthy image generation. Deep Neural Networks (DNN) have a powerful ability to express complex nonlinear functions. This research paper introduces a novel framework based on DNN aiming to achieve EIT image reconstruction. The proposed DNN model, comprises of the following two layers, namely: The Stacked Autoencoder (SAE) and the Logistic Regression (LR). It is trained using the large lab samples which are obtained by the COMSOL simulation software (a cross platform finite elements analysis solver). The relationship between the voltage measurement and the internal conductivity distribution is determined. The untrained voltage measurement samples are used as input to the trained DNN, and the output is an estimate for image reconstruction of the internal conductivity distribution. The results show that the proposed model can achieve reliable shape and size reconstruction. When white Gaussian noise with a signal-to-noise ratio of 30, 40 and 50 were added to test set, the proposed DNN structure still has good imaging results, which proved the anti-noise capability of the network. Furthermore, the network that was trained using simulation data sets, would be applied for the EIT image reconstruction based on the experimental data that were produced after preprocessing.

Modern Electromobility and the Possibility of How to Achieve a Higher Capacity of the Li-ion Batteries

2021 ◽  
Vol 105 (1) ◽  
pp. 665-672
Author(s):  
Martin Šedina ◽  
Tomas Kazda
Keyword(s):  
Anode Materials ◽  
External Pressure ◽  
Promising Material ◽  
Li Ion Batteries ◽  
Conversion Materials ◽  
Basic Parameters ◽  
Li Ion ◽  
New Challenges ◽  
Internal Conductivity

This article is describing the evolution of modern electromobilitywith describing the problematics connected with the shape of cells in battery modules. There are mentioned Li-ion battery's anode materials with their basic parameters and one of the conversion materials, silicon, which looks like promising material for future enhancing anode capacity. Usage of this material brings some new challenges, which prevents use in practice and must be solved. One of these solutions can be by applying external pressure, which can, for example, improve internal conductivity

scholarly journals The internal conductivity of non-irritable muscle

1928 ◽  
Vol 65 (2) ◽  
pp. 214-223 ◽  
Author(s):  
David Landsborough Thomson
Keyword(s):  
Internal Conductivity

scholarly journals The Relationship of Internal Conductance and Membrane Capacity to Mitochondrial Volume

1960 ◽  
Vol 7 (4) ◽  
pp. 603-612 ◽  
Author(s):  
Helmut Pauly ◽  
Lester Packer
Keyword(s):  
External Medium ◽  
Chloride Concentration ◽  
Guinea Pig Heart ◽  
Membrane Capacity ◽  
Internal Conductance ◽  
Electrical Capacity ◽  
Mitochondrial Volume ◽  
Internal Conductivity ◽  
Relationship Of ◽  
The Relationship

A study was made of the effect of mitochondrial size on the electrical properties of the membrane and the internal conductivity of mitochondria. The dielectric constant and electrical conductivity of suspensions of guinea pig heart mitochondria were examined in the frequency range 5 x 105 to 2.5 x 108 C.P.S. Membrane capacity was calculated to be 1.1 to 1.3 µf./cm.2 and was virtually the same in mitochondria whose surface area was made to vary by a factor of 4 by osmotic means. This finding suggested that some mechanism must exist for the transfer of mitochondrial material into membrane structure during fluctuations in mitochondrial size. The electrical capacity of the membrane was unaffected by a 33-fold change in potassium chloride concentration. The internal conductance of swollen mitochondria was 2 to 3 times lower than that of the external medium. In shrunken mitochondria the internal conductance was virtually independent of the conductivity of the external medium. These results were discussed in relation to current concepts of mitochondrial structure.

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