Application of analytical electron microscopy to the study of partitioning of silicon in a 2 wt% Si eutectoid steel

1978 ◽  
Vol 36 (1) ◽  
pp. 616-617
Author(s):  
N. Ridley ◽  
S.A. Al-Salman ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Analytical Electron Microscopy ◽  
Eutectoid Steel ◽  
Minimum Diameter ◽  
Thin Foils ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Transformation Front

The application of the technique of analytical electron microscopy to the study of partitioning of Mn (1) and Cr (2) during the austenite-pearlite transformation in eutectoid steels has been described in previous papers. In both of these investigations, ‘in-situ’ analyses of individual cementite and ferrite plates in thin foils showed that the alloying elements partitioned preferentially to cementite at the transformation front at higher reaction temperatures. At lower temperatures partitioning did not occur and it was possible to identify a ‘no-partition’ temperature for each of the steels examined.In the present work partitioning during the pearlite transformation has been studied in a eutectoid steel containing 1.95 wt% Si. Measurements of pearlite interlamellar spacings showed, however, that except at the highest reaction temperatures the spacing would be too small to make the in-situ analysis of individual cementite plates possible, without interference from adjacent ferrite lamellae. The minimum diameter of the analysis probe on the instrument used, an EMMA-4 analytical electron microscope, was approximately 100 nm.

Analysis of Dark-Field Images of Disordered Materials

1972 ◽  
Vol 30 ◽  
pp. 560-561
Author(s):  
J. M. Cowley
Keyword(s):  
Amorphous Materials ◽  
Careful Analysis ◽  
Dark Field ◽  
Minimum Diameter ◽  
Statistical Fluctuations ◽  
Bright Spots ◽  
Sufficient Detail ◽  
Random Arrangement ◽  
Diffraction Patterns ◽  
Imaging Conditions

Recently a number of authors have reported detail in dark-field images obtained from diffuse-scattering regions of electron diffraction patterns. Bright spots in images from short-range order diffuse peaks of disordered binary alloys have been interpreted as evidence for the existence of microdomains of ordered lattice or of segragated clusters of one component. Spotty contrast in dark field images of near-amorphous materials has been interpreted as evidence for the existense of microcrystals. Without a careful analysis of the imaging conditions such conclusions may be invalid. Usually the conditions of the experiment have not been specified in sufficient detail to allow evaluation of the conclusions.Elementary considerations show that even for a completely random arrangement of atoms the statistical fluctuations of density will give a spotty contrast with spots of minimum diameter determined by the dark field aperture size and other factors influencing the minimum resolvable distance under darkfield imaging conditions, including fluctuations and drift over long exposure times (resolution usually 10Å or more).

VLS Growth of Si nanowhiskers on a H-terminated Si{111} surface

1998 ◽  
Vol 536 ◽  
Author(s):  
N. Ozaki ◽  
Y. Ohno ◽  
S. Takeda ◽  
M. Hirata
Keyword(s):  
High Pressure ◽  
Growth Condition ◽  
Growth Mechanism ◽  
Quantum Confinement ◽  
Critical Value ◽  
Extended Defects ◽  
Vapor Liquid Solid ◽  
Minimum Diameter ◽  
Vls Growth ◽  
Vapor Liquid

AbstractWe have grown Si nanowhiskers on a Si{1111} surface via the vapor-liquid-solid (VLS) mechanism. The minimum diameter of the crystalline is 3nm and is close to the critical value for the effect of quantum confinement. We have found that many whiskers grow epitaxially or non-epitaxially on the substrate along the 〈112〉 direction as well as the 〈111〉 direction.In our growth procedure, we first deposited gold on a H-terminated Si{111} surface and prepared the molten catalysts of Au and Si at 500°C. Under the flow of high pressure silane gas, we have succeeded in producing the nanowhiskers without any extended defects. We present the details of the growth condition and discuss the growth mechanism of the nanowhiskers extending along the 〈112〉 direction.

scholarly journals Modeling Diameter Distributions with Six Probability Density Functions in Pinus halepensis Mill. Plantations Using Low-Density Airborne Laser Scanning Data in Aragón (Northeast Spain)

2021 ◽  
Vol 13 (12) ◽  
pp. 2307
Author(s):  
J. Javier Gorgoso-Varela ◽  
Rafael Alonso Ponce ◽  
Francisco Rodríguez-Puerta
Keyword(s):  
Probability Density ◽  
Linear Models ◽  
Pinus Halepensis ◽  
Beta Function ◽  
Probability Density Functions ◽  
Lidar Data ◽  
Density Functions ◽  
Minimum Diameter ◽  
Location Parameters ◽  
Diameter Distributions

The diameter distributions of trees in 50 temporary sample plots (TSPs) established in Pinus halepensis Mill. stands were recovered from LiDAR metrics by using six probability density functions (PDFs): the Weibull (2P and 3P), Johnson’s SB, beta, generalized beta and gamma-2P functions. The parameters were recovered from the first and the second moments of the distributions (mean and variance, respectively) by using parameter recovery models (PRM). Linear models were used to predict both moments from LiDAR data. In recovering the functions, the location parameters of the distributions were predetermined as the minimum diameter inventoried, and scale parameters were established as the maximum diameters predicted from LiDAR metrics. The Kolmogorov–Smirnov (KS) statistic (Dn), number of acceptances by the KS test, the Cramér von Misses (W2) statistic, bias and mean square error (MSE) were used to evaluate the goodness of fits. The fits for the six recovered functions were compared with the fits to all measured data from 58 TSPs (LiDAR metrics could only be extracted from 50 of the plots). In the fitting phase, the location parameters were fixed at a suitable value determined according to the forestry literature (0.75·dmin). The linear models used to recover the two moments of the distributions and the maximum diameters determined from LiDAR data were accurate, with R2 values of 0.750, 0.724 and 0.873 for dg, dmed and dmax. Reasonable results were obtained with all six recovered functions. The goodness-of-fit statistics indicated that the beta function was the most accurate, followed by the generalized beta function. The Weibull-3P function provided the poorest fits and the Weibull-2P and Johnson’s SB also yielded poor fits to the data.

scholarly journals Aortic Annular Sizing Using Novel Software in Three-Dimensional Transesophageal Echocardiography for Transcatheter Aortic Valve Replacement: A Systematic Review and Meta-Analysis

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 751
Author(s):  
Chanrith Mork ◽  
Minjie Wei ◽  
Weixi Jiang ◽  
Jianli Ren ◽  
Haitao Ran
Keyword(s):  
Aortic Valve ◽  
Aortic Valve Replacement ◽  
Transesophageal Echocardiography ◽  
Valve Replacement ◽  
Transcatheter Aortic Valve Replacement ◽  
Meta Analysis ◽  
Three Dimensional ◽  
Minimum Diameter ◽  
Transcatheter Aortic Valve ◽  
Mean Differences

(1) Background: We performed this study to evaluate the agreement between novel automated software of three-dimensional transesophageal echocardiography (3D-TEE) and multidetector computed tomography (MDCT) for aortic annular measurements of preprocedural transcatheter aortic valve replacement (TAVR); (2) Methods: PubMed, EMBASE, Web of Science, and Cochrane Library (Wiley) databases were systematically searched for studies that compared 3D-TEE and MDCT as the reference standard for aortic annular measurement of the following parameters: annular area, annular perimeter, area derived-diameter, perimeter derived-diameter, maximum and minimum diameter. Meta-analytic methods were utilized to determine the pooled correlations and mean differences between 3D-TEE and MDCT. Heterogeneity and publication bias were also assessed. Meta-regression analyses were performed based on the potential factors affecting the correlation of aortic annular area; (3) Results: A total of 889 patients from 10 studies were included in the meta-analysis. Pooled correlation coefficients between 3D-TEE and MDCT of annulus area, perimeter, area derived-diameter, perimeter derived-diameter, maximum and minimum diameter measurements were strong 0.89 (95% CI: 0.84–0.92), 0.88 (95% CI: 0.83–0.92), 0.87 (95% CI: 0.77–0.93), 0.87 (95% CI: 0.77–0.93), 0.79 (95% CI: 0.64–0.87), and 0.75 (95% CI: 0.61–0.84) (Overall p < 0.0001), respectively. Pooled mean differences between 3D-TEE and MDCT of annulus area, perimeter, area derived-diameter, perimeter derived-diameter, maximum and minimum diameter measurements were −20.01 mm2 ((95% CI: −35.37 to −0.64), p = 0.011), −2.31 mm ((95% CI: −3.31 to −1.31), p < 0.0001), −0.22 mm ((95% CI: −0.73 to 0.29), p = 0.40), −0.47 mm ((95% CI: −1.06 to 0.12), p = 0.12), −1.36 mm ((95% CI: −2.43 to −0.30), p = 0.012), and 0.31 mm ((95% CI: −0.15 to 0.77), p = 0.18), respectively. There were no statistically significant associations with the baseline patient characteristics of sex, age, left ventricular ejection fraction, mean transaortic gradient, and aortic valve area to the correlation between 3D-TEE and MDCT for aortic annular area sizing; (4) Conclusions: The present study implies that 3D-TEE using novel software tools, automatically analysis, is feasible to MDCT for annulus sizing in clinical practice.

Risk Factors For Recurrent Myopic Macular Hole Retinal Detachment After Silicone Oil Removal In Patients With Open Flat Macular Hole

2021 ◽  
Author(s):  
Hamouda Hamdy Ghoraba ◽  
Hosam Othman Mansour ◽  
Mohamed Ahmed Abdelhafez Elsayed ◽  
Adel Galal Zaky ◽  
Mohamed Amin Heikal ◽  
...  
Keyword(s):  
Risk Factors ◽  
Retinal Detachment ◽  
Macular Hole ◽  
Silicone Oil ◽  
Significant Risk ◽  
Minimum Diameter ◽  
Univariate Logistic Regression Analysis ◽  
Macular Hole Retinal Detachment ◽  
Myopic Macular Hole ◽  
Group 2

Purpose: To evaluate the risks that might be associated with recurrent macular hole retinal detachment (Re MHRD) after silicone oil (S.O) removal in myopic patients with open flat macular hole (MH). Methods: In this retrospective series, we assessed the different factors that might be associated with recurrent MHRD after S.O removal in 48 eyes with open flat MH that underwent S.O removal after successful MHRD repair by dividing the enrolled eyes into 2 groups: group 1 included 38 eyes with flat open MH and flat retina after S.O removal and group 2 included 10 eyes with flat open MH and recurrent MHRD after S.O removal. Results: Ten of 48 eyes (20.8%) with open flat MH developed recurrent MHRD after S.O removal. Univariate logistic regression analysis revealed that MH at the apex of PS, MH minimum diameter, hole form factor (HFF) and MH index (MHI) were significant risk factors for recurrent MHRD after S.O removal in myopic patients with open flat MH. Conclusions: If there is a "flat open" MH that is large, located at the apex of PS or with HHF or MHI of less than 0.9-0.5, it has a high chance of recurrent MHRD after S.O removal.

scholarly journals Selection of filter parameters of Individual water supply systems

2019 ◽  
Vol 110 ◽  
pp. 01072 ◽  
Author(s):  
Vladimir Shcherbakov ◽  
Aleksandr Akulshin ◽  
Aleksandr Bachmetev ◽  
Anatolyi Akulshin
Keyword(s):  
Water Supply ◽  
Water Intake ◽  
Small Diameter ◽  
Design Flow ◽  
Water Supply Systems ◽  
Minimum Diameter ◽  
Water Well ◽  
Pumping Equipment ◽  
The Cost ◽  
Supply Systems

The paper is devoted to the problem of optimal design, construction and operation of water supply systems and their elements. The key element of the system is a water well. The quality of its design and construction determines the operation of the water intake as a whole. Disadvantages in the construction of a well lead to disruption of the entire water supply system of a particular object. The paper proposed a methodology for selecting the optimal diameter and length of the well filter of a water well. Based on the methodology, an example of filter parameters selection for hydrogeological conditions of the city of Kursk is given. The above calculation showed that the use of the entrance velocity criterion in the design of wells can significantly reduce the cost of well construction while ensuring the design flow rate and allowable lowering of the water level. The cost of the filter, depending on the well design, is 20-30% of the total price for its construction. The most important filter parameters affecting the cost of a well are its length and diameter. Justifying the minimum diameter of the filter that ensures the designed water intake and allowable dewatering can significantly reduce the cost of the well, taking into account the fact that modern pumping equipment allows the use of columns of small diameter above the filter.

scholarly journals Conventional Selection of Mechanical Fasteners for Flat Belts

2021 ◽  
Vol 11 (7) ◽  
pp. 2916
Author(s):  
Karol Konecki ◽  
Dominik Wojtkowiak ◽  
Krzysztof Talaśka ◽  
Andrzej Kołodziej ◽  
Grzegorz Domek
Keyword(s):  
Conveyor Belt ◽  
Minimum Diameter ◽  
Fabric Composite ◽  
Mechanical Fasteners ◽  
Problematic Issue ◽  
Mechanical Fastening ◽  
Materials Used ◽  
Belt Conveyors ◽  
Mechanical Fastener ◽  
The Right

Due to the variety of materials used for flat belts of belt conveyors and the further development of material engineering in relation to these belts, the methods of their connection become an increasingly problematic issue. The belts can be connected mainly in three ways: vulcanized (weldable or heat-weldable), glued or mechanically. The latter method is one of the simplest and most universal in terms of the material variety of belts; however, there are many design variations of mechanical fasteners, and each of them has a certain advantage in a narrow group of properties, e.g., the thickness spectrum of a conveyor belt, the minimum diameter of a drive roller or the range of transferable longitudinal loads. The objective of this paper is to analyze the design solutions of commercial mechanical fasteners used mainly for flat rubber-fabric, composite or plastic belts. To fulfill this goal, a preliminary analysis of the stress distribution for an exemplary solid mechanical fastener was carried out in two cases: during ramp-up and during circulating around the roll, followed by a detailed review of commercial solutions available on the market. In addition to determining the current state of knowledge and technology and determining the state of ignorance, special algorithm and design maps have been created, thanks to which the process of selecting the right mechanical fastening will be easier. The overview includes several tables with detailed information on individual connection properties. Additionally, several design aspects were derived, within which individual mechanical connections may differ. This is to enable the generation of customized solutions in the future by proposing an appropriate mathematical model, on the basis of which it will be possible to generate optimal design properties for a given application.

Numerical study of sheared mobile polydisperse sediment beds with a coupled lattice Boltzmann - discrete element method

2021 ◽  
Author(s):  
Christoph Rettinger ◽  
Sebastian Eibl ◽  
Ulrich Rüde ◽  
Bernhard Vowinckel
Keyword(s):  
Discrete Element Method ◽  
Lattice Boltzmann ◽  
Numerical Study ◽  
Experimental Studies ◽  
Discrete Element ◽  
Parallel Execution ◽  
Coupling Mechanism ◽  
Size Segregation ◽  
Minimum Diameter ◽  
Element Method

&lt;p&gt;With the increasing computational power of today's supercomputers, geometrically fully resolved simulations of particle-laden flows are becoming a viable alternative to laboratory experiments. Such simulations enable detailed investigations of transport phenomena in various multiphysics scenarios, such as the coupled interaction of sediment beds with a shearing fluid flow. There, the majority of available simulations as well as experimental studies focuses on setups of monodisperse particles. In reality, however, polydisperse configurations are much more common and feature unique effects like vertical size segregation.&lt;/p&gt;&lt;p&gt;In this talk, we will present numerical studies of mobile polydisperse sediment beds in a laminar shear flow, with a ratio of maximum to minimum diameter up to 10. The lattice Boltzmann method is applied to represent the fluid dynamics through and above the sediment bed efficiently. We model particle interactions by a discrete element method and explicitly account for lubrication forces. The fluid-particle coupling mechanism is based on the geometrically fully resolved momentum transfer between the fluid and the particulate phase. We will highlight algorithmic aspects and communication schemes essential for massively parallel execution.&lt;/p&gt;&lt;p&gt;Utilizing these capabilities allows us to achieve large-scale simulations with more than 26.000 densely-packed polydisperse particles interacting with the fluid. With this, we are able to reproduce effects like size segregation and to study the rheological behavior of such systems in great detail. We will evaluate and discuss the influence of polydispersity on these processes. These insights will be used to improve and extend existing macroscopic models.&lt;/p&gt;

Computational Study of Atomization Models and Optimal Design of a Pressurized Inhaler

2021 ◽  
Vol 50 ◽  
pp. 123-134
Author(s):  
Anurag Tiwari ◽  
Siddharth Sharma ◽  
Vivek Kumar Srivastav ◽  
Anuj Jain ◽  
Akshoy Ranjan Paul
Keyword(s):  
Drug Delivery ◽  
Particle Production ◽  
Computational Study ◽  
Nozzle Diameter ◽  
Inhalation Therapy ◽  
Respiratory Drug Delivery ◽  
Minimum Diameter ◽  
Inhaler Device ◽  
Swirl Atomizer ◽  
Pressure Swirl

Respiratory drug delivery has been under the spotlight of research for the past few decades, mainly due to rapid increase of pulmonary diseases. This type of drug delivery offers the highest efficiency for treatment. Despite its numerous benefits, there are some drawbacks in the method of respiratory drug delivery-the most important being poor delivery efficiency and high drug deposition in undesirable regions, such as the oropharynx. This study is focused on improving pressurized inhaler device, which is one of the most used devices for inhalation therapy throughout the world using the results and findings obtained from numerical analysis. In this study, three atomizer models are investigated and found that pressure swirl atomizer model closely represents the atomization phenomenon from a pressurized inhaler device. Parametric study is carried out using three parameters: nozzle diameter, dispersion angle and sheet constant to optimize the performance of the device. It is revealed that a reduction in nozzle diameter and dispersion angle help in generating fine (smaller diameter) particles, whereas increase in sheet constant is responsible for fine particle production. The values of nozzle diameter, dispersion angle and sheet constant are tuned to get the particles with minimum diameter as output which is desirable for the drug particles to get deposited in the smaller airways of lungs and increase the efficiency of drug delivery and improve the device performance.

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