scholarly journals Analysis on non-stationary gyroscopes and their application in measurement technology

2021 ◽  
Vol 2091 (1) ◽  
pp. 012006
Author(s):  
A I Andreev ◽  
A P Perekrestov
Keyword(s):  
Center Of Mass ◽  
Interesting Case ◽  
Center Of Gravity ◽  
Point Of View ◽  
Measurement Technology ◽  
Measuring Instruments ◽  
Body Of Revolution ◽  
Gravitational Fields ◽  
First Case ◽  
Working Medium

Abstract In this work, the main subjects of research are: 1) analysis of the process of rotation of a Chinese top on a flat surface, 2) analysis of the main dependencies and an explanation of the rise of the center of gravity of the top during rotation due to nonlinear friction and the resulting force of the overturning top on the upper axis. Also, an analytical study of the motion of the top along the plane and the laws of rotation was carried out, the rotation of the top was analyzed from the point of view of asymmetry during rotation. The top-top spinning top is an interesting case of raising the center of gravity during rotation. The simplest model of a Chinese top can be a dynamic symmetric inhomogeneous ball, the center of mass of which lies on the axis of dynamic symmetry, but does not coincide with its geometric center. The precession of the Chinese top is based on dry friction. The occurrence of a gyroscopic deflection moment is based on the frictional force. Considering the simplest top-type top, one can distinguish the main forces acting on this body, as well as its characteristics that determine the precession. Based on this fact, it is possible to propose the use of this body of revolution as a working medium for instruments such as tribometers and gravimeters. In the first case, this makes it possible to increase the accuracy of the device, in the second, to create a new scheme for measuring gravitational fields. The relevance of this work is the analysis of the rotation of the Chinese top and the possibility of its use in measuring instruments.

Center of Gravity and Center of Mass

1938 ◽  
Vol 6 (2) ◽  
pp. 106-106 ◽  
Author(s):  
Michael Ference ◽  
Alvin M. Weinberg
Keyword(s):  
Center Of Mass ◽  
Center Of Gravity

scholarly journals Examination of Weight Transfer Strategies During the Execution of Grand Battement Devant at the Barre, in the Center, and Traveling

2012 ◽  
Vol 27 (2) ◽  
pp. 74-84 ◽  
Author(s):  
Donna Krasnow ◽  
M Virginia Wilmerding ◽  
Shane Stecyk ◽  
Matthew Wyon ◽  
Yiannis Koutedakis
Keyword(s):  
Center Of Mass ◽  
Center Of Gravity ◽  
Main Effect ◽  
Transfer Strategies ◽  
Center Conditions ◽  
Primary Focus ◽  
Dance Educators ◽  
Weight Transfer ◽  
Motor Strategies ◽  
Effect Condition

The purpose of this study was to examine grand battement devant at the barre, in the center, and traveling through space. The primary focus was to consider weight transfer in three conditions: from two feet to one foot for the barre and center conditions, and from one foot to the other foot in traveling. Forty female dancers volunteered (mean age 30.0 ± 13.0 yrs) and were placed in three groups: beginner (n = 12), intermediate (n = 14), and advanced (n = 14). Data were collected with a 7-camera Vicon motion capture system using a Plug-in Gait Full Body Marker set and with two Kistler force plates. Dancers executed five grand battement devant in each of three conditions in randomized order: at the barre in 1st position, in the center in 1st position, and traveling through space. Four variables were investigated: center of gravity of the full trunk, center of gravity of the pelvis, center of gravity of the upper trunk, and center of mass. Data were analyzed in three intervals—stance to battement initiation (STN to GBI), initiation to battement peak (GBI to GBP), and peak to end (GBP to END)—and in the x-axis and y-axis. The main effect condition was significant for all four variables in both x-axis and y-axis (p<0.001). There were no significant differences for training and no significant condition 3 training interactions. Condition was significant for all three intervals (STN to GBI, GBI to GBP, and GBP to END) for all four variables in both axes (p<0.01). Dance educators might consider the importance of allocating sufficient time in dance practice to each of the three conditions—barre, center, and traveling—to ensure development of a variety of motor strategies for weight transfer.

scholarly journals Web Application for Statistical Tracking and Predicting the Evolution of Active Cases with the Novel Coronavirus (SARS-CoV-2)

2021 ◽  
pp. 70-74
Author(s):  
Iulia Clitan ◽  
◽  
Adela Puscasiu ◽  
Vlad Muresan ◽  
Mihaela Ligia Unguresan ◽  
...  
Keyword(s):  
Neural Network ◽  
Mathematical Model ◽  
Web Application ◽  
Point Of View ◽  
The Novel ◽  
End User ◽  
First Case ◽  
Novel Coronavirus ◽  
Second Wave ◽  
Over Time

Since February 2020, when the first case of infection with SARS COV-2 virus appeared in Romania, the evolution of COVID-19 pandemic continues to have an ascending allure, reaching in September 2020 a second wave of infections as expected. In order to understand the evolution and spread of this disease over time and space, more and more research is focused on obtaining mathematical models that are able to predict the evolution of active cases based on different scenarios and taking into account the numerous inputs that influence the spread of this infection. This paper presents a web responsive application that allows the end user to analyze the evolution of the pandemic in Romania, graphically, and that incorporates, unlike other COVID-19 statistical applications, a prediction of active cases evolution. The prediction is based on a neural network mathematical model, described from the architectural point of view.

scholarly journals MECHANICAL STRENGTH OF COAL: METHODS OF DETERMINATION AND FACTORS OF INFLUENCE (REVIEW)

2021 ◽  
Vol 6 ◽  
pp. 4-17
Author(s):  
V.V Koval ◽  
D.V. Miroshnichenko ◽  
O.V. Bogoyavlenska
Keyword(s):  
Mechanical Strength ◽  
Physical Properties ◽  
Physical And Mechanical Properties ◽  
Mechanical Tests ◽  
Point Of View ◽  
Statistical Characteristics ◽  
Measuring Instruments ◽  
Industrial Processing ◽  
Average Value ◽  
Advantages And Disadvantages

The article substantiates the importance and problems of determining of such an indicator of the quality of solid fossil fuels, as mechanical strength. The strength of coal depends on a large number of factors (viscosity, brittleness, properties of structural bonds, etc.), the change of which is impossible to take into account. Therefore, the strength of coal in the sample, piece, pack and formation must be represented by some integral index, which inevitably fluctuates around a certain average value and can be determined only approximately. The evaluation of the strength properties of coal should be carried out on the basis of mass tests using statistical methods that allow to calculate the average value and coefficient of variation. Since the strength dispersion is mainly due to the natural inhomogeneity of the coal, the excessive accuracy of the measuring instruments has almost no effect on the statistical characteristics. Laboratory methods of mechanical tests of mine samples, in comparison with full-scale, as a rule, are very accessible and, at qualitative performance of tests, are highly reliable. The properties of coal as an object of enrichment and use are largely related to its physical properties. The physical properties of coal and mineral impurities significantly affect the formation of the main parameters that characterize the particle size distribution and fractional composition, it`s changes during the mining, transportation and enrichment processes. The basic physical and mechanical properties of solid fuels from the point of view of their industrial processing have been listed, the review has been made of the most widespread methods of study of coals mechanical durability and the equipment used for these purposes. The main advantages and disadvantages have been summarized of these methods, as well as their relationship. The factors have been Indicated tinfluencing the mechanical strength of coal. The expediency of using existing methods from the point of view of informativeness for thesphere of its application has been estimated. The methods common in the coal processing industry are considered in more detail. Keywords: coal, solid fuel mining, mechanical strength, determination methods, influencing factors, grinding strength, crushing index. Corresponding author V.V. Koval, e-mail: [email protected]

Center of Gravity, Center of Mass,Centroids

2016 ◽  
pp. 29-44
Author(s):  
Dietmar Gross ◽  
Wolfgang Ehlers ◽  
Peter Wriggers ◽  
Jörg Schröder ◽  
Ralf Müller
Keyword(s):  
Center Of Mass ◽  
Center Of Gravity ◽  
Gravity Center

A diagnostic pitfall in hepatic mesenchymal hamartoma mimicking hepatoblastoma: A case report

2020 ◽  
Author(s):  
Zhihong Chen ◽  
Lutong Fang ◽  
Ying Zhang ◽  
Yuanzi Ye ◽  
Wenshu Ji ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Female Child ◽  
Point Of View ◽  
Mesenchymal Hamartoma ◽  
Diagnostic Pitfall ◽  
First Case ◽  
Contrast Enhanced ◽  
Enhanced Ct ◽  
Vascular Channels ◽  
The Right

Abstract Background: Hepatic mesenchymal hamartoma (HMH) is an uncommon benign tumor in children. While mesenchymal hamartomas may be angiomatous and blood vessels may be identified, HMH with a malignant tumor symptom on the contrast-enhanced hepatic computed tomography angiography (CTA) has not been described. Here, we present the first case of HMH mimicking hepatoblastoma on the hepatic CTA from pathological point of view and review the imaging and histological features of this unique lesion. Case presentation: A 2-year-old female child was found a distention in the right abdomen and was admitted to our hospital. The Hepatic CTA showed that the blood vessels were thickened, the tumor blood vessels were clustered in the tumor. According to the hepatic CT findings, the tumor was considered to be malignant, possibly a hepatoblastoma. Microscopic examination showed a tumor arranged in lobules, composed of loose myxoid mesenchyme surrounding ductal structures, with intervening vascular channels. The Immunohistochemical staining revealed positive CK7 and CD34 for the bile duct elements and the lining endothelial cells of the vascular channels. There were abundant blood vessels around the nodules and the margins of remaining hepatocytes, but few in the central region. The blood vessels are small, thin-walled vessels and presented like capillaries and venules. Conclusions: A histological diagnosis of Hepatic Mesenchymal Hamartoma was confirmed by the microscopic examinations. This case adds learning points to radiologists when heterogeneous reinforcement on enhanced CT scan was presented in such a large childhood liver tumor.

scholarly journals Complete laparoscopic pancreaticoduodenectomy: our experience of the first case

2019 ◽  
Vol 22 (1) ◽  
pp. 26-30
Author(s):  
Mukund Raj Joshi ◽  
Sujan Regmee ◽  
Tanka Prasad Bohara ◽  
Rupesh Chakradhar ◽  
Mandesh Shrestha
Keyword(s):  
Blood Loss ◽  
Point Of View ◽  
Resected Specimen ◽  
Laparoscopic Pancreaticoduodenectomy ◽  
Technical Aspects ◽  
Technical Point ◽  
Operative Outcomes ◽  
Post Operative Period ◽  
First Case

Laparoscopic pancreaticoduodenectomy was described in 1994. It is considered the most challenging abdominal surgery. Although the procedure was found to be feasible in initial reports, the benefits were not considered favorable. In recent days, with the increasing experience of surgeons, acceptable outcomes are being observed and have been found to be technically beneficial and oncologically safe in selective cases in experienced hands. We performed the procedure in a 42-year-old gentleman with good operative and post-operative outcomes. The patient’s follow-up for six post-operative months seems satisfactory. The operation took 840 minutes with minimal blood loss. The resected specimen was adequate and satisfactory from an oncological and technical point of view. The patient developed some inherent complications of the procedure in the post-operative period. He recovered well. Details of the case and technical aspects are being discussed.  

scholarly journals Exceptional Experiences of Stable and Unstable Mental States, Understood from a Dual-Aspect Point of View

Philosophies ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 7 ◽  
Author(s):  
Harald Atmanspacher ◽  
Wolfgang Fach
Keyword(s):  
State Space ◽  
Empirical Support ◽  
Mental States ◽  
Interesting Case ◽  
Point Of View ◽  
Asymptotically Stable ◽  
World Model ◽  
State Space Approach ◽  
Generalized Potential ◽  
Space Approach

Within a state-space approach endowed with a generalized potential function, mental states can be systematically characterized by their stability against perturbations. This approach yields three major classes of states: (1) asymptotically stable categorial states, (2) marginally stable non-categorial states and (3) unstable acategorial states. The particularly interesting case of states giving rise to exceptional experiences will be elucidated in detail. Their proper classification will be related to Metzinger’s account of self-model and world-model, and empirical support for this classification will be surveyed. Eventually, it will be outlined how Metzinger’s discussion of intentionality achieves pronounced significance within a dual-aspect framework of thinking.

Some “laws” of gastropod shell form

Paleobiology ◽  
1977 ◽  
Vol 3 (2) ◽  
pp. 196-206 ◽  
Author(s):  
Robert M. Linsley
Keyword(s):  
Center Of Mass ◽  
Mantle Cavity ◽  
Center Of Gravity ◽  
The Body ◽  
Water Current ◽  
Gastropod Shell ◽  
Shell Form ◽  
Body Whorl ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

Five generalizations derived from the shell form of prosobranch gastropods are developed. (1) A univalve of more than one volution whose aperture lies in a plane that passes through the axis of coiling does not live with the aperture parallel to the substrate. (2) A univalve of more than one volution whose aperture lies in a plane that is tangential to the body whorl does live with the plane of the aperture parallel to the substrate. (3) Gastropods with tangential apertures, when extended, support the shell so that the center of mass of the shell and its contents is over the midline of the cephalopedal mass; this balancing of the shell may be accomplished either by regulatory detorsion, by inclination or by a combination thereof, to keep the center of gravity of the shell as low as possible. (4) Angulations or re-entrants in the gastropod aperture are usually indicative of inhalent or exhalent areas; inhalent areas are directed as far anteriorly as possible. (5) Gastropods having elongated apertures possess only a single gill and develop a water current through the mantle cavity from anterior to posterior along the long axis of the aperture; this axis is subparallel to the anterior-posterior axis of the foot.These generalizations are then used as the basis for some deductive interpretations of behavioral modes of Paleozoic Gastropoda.

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