scholarly journals Algorithms for Particle Detection in Complex Plasmas

2019 ◽  
Vol 5 (2) ◽  
pp. 30
Author(s):  
Daniel Mohr ◽  
Christina Knapek ◽  
Peter Huber ◽  
Erich Zaehringer
Keyword(s):  
Moment Method ◽  
Granular Matter ◽  
Synthetic Data ◽  
Single Particles ◽  
Particle Detection ◽  
Threshold Detection ◽  
Video Cameras ◽  
The Moment ◽  
Complex Plasmas ◽  
The Impact

In complex plasmas, the behavior of freely floating micrometer sized particles is studied. The particles can be directly visualized and recorded by digital video cameras. To analyze the dynamics of single particles, reliable algorithms are required to accurately determine their positions to sub-pixel accuracy from the recorded images. Typically, a straightforward algorithm such as the moment method is used for this task. Here, we combine different variations of the moment method with common techniques for image pre- and post-processing (e.g., noise reduction and fitting), and we investigate the impact of the choice of threshold parameters, including an automatic threshold detection, on synthetic data with known attributes. The results quantitatively show that each algorithm and method has its own advantage, often depending on the problem at hand. This knowledge is applicable not only to complex plasmas, but useful for any kind of comparable image-based particle tracking, e.g., in the field of colloids or granular matter.

Bubble Formation at Impingement of a Liquid Droplet on a Solid Surface

2000 ◽  
Author(s):  
Hitoshi Fujimoto ◽  
Tomoyuki Ogino ◽  
Osamu Takahashi ◽  
Hirohiko Takuda ◽  
Natsuo Hatta
Keyword(s):  
Solid Surface ◽  
Liquid Droplet ◽  
Droplet Diameter ◽  
Bubble Formation ◽  
Liquid Droplets ◽  
Vapor Bubbles ◽  
Experimental Conditions ◽  
Video Cameras ◽  
The Moment ◽  
The Impact

Abstract The collision of liquid droplets with a solid has been studied experimentally. The time evolution of the liquid/solid contact area as well as the shape of droplets has been observed by means of a flash-photographic method using two video cameras. It has been found that some air between the solid surface and the incoming droplet is entrapped at the moment of impact. In the case where the solid temperature is high (= 450 °C), numerous vapor bubbles appear at the liquid/solid interface after the collision. The bubble formation due to the entrapment of air has been examined for various experimental conditions. Water, and ethanol are used as test liquid. The droplet diameter is 2.4 mm for water and 1.9 mm for ethanol. The impact velocity varies from 0.8 to 3.1 m/s. The entrapment of air has been observed for both liquids under all conditions in the present study.

scholarly journals Evaluating the Dynamic Response of the Bridge-Vehicle System considering Random Road Roughness Based on the Moment Method

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Fan Feng ◽  
Fanglin Huang ◽  
Weibin Wen ◽  
Zhe Liu ◽  
Xiang Liu
Keyword(s):  
Random Process ◽  
Moment Method ◽  
System Response ◽  
Vehicle Speed ◽  
The Road ◽  
Bridge Span ◽  
Road Roughness ◽  
System Vibration ◽  
The Moment ◽  
The Impact

The bridge-vehicle interaction (BVI) system vibration is caused by the vehicles passing through the bridge. The road roughness has a great impact on the system vibration. In this regard, poor road roughness is known to affect the comfort of the vehicle crossing the bridge and aggravate the fatigue damage of the bridge. Road roughness is usually regarded as a random process in numerical calculation. To fully consider the influence of road roughness randomness on the response of the BVI system, a random BVI model was established. Thereafter, the random process of road roughness was expressed by Karhunen–Loeve expansion (KLE), after which the moment method was used to calculate the maximum probability value of the BVI system response. The proposed method has higher accuracy and efficiency than the Monte Carlo simulation (MCS) calculation method. Subsequently, the influences of vehicle speed, roughness grade, and bridge span on the impact factor (IMF) were analyzed. The results show that the road roughness grade has a greater impact on the bridge IMF than the bridge span and vehicle speed.

scholarly journals Modelling the impact of delaying vaccination against SARS-CoV-2 assuming unlimited vaccine supply

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Marcos Amaku ◽  
Dimas Tadeu Covas ◽  
Francisco Antonio Bezerra Coutinho ◽  
Raymundo Soares Azevedo ◽  
Eduardo Massad
Keyword(s):  
Mathematical Model ◽  
Vaccination Campaign ◽  
Vaccination Rate ◽  
Sao Paulo ◽  
The State ◽  
São Paulo ◽  
Health Authorities ◽  
The World ◽  
The Moment ◽  
The Impact

Abstract Background At the moment we have more than 177 million cases and 3.8 million deaths (as of June 2021) around the world and vaccination represents the only hope to control the pandemic. Imperfections in planning vaccine acquisition and difficulties in implementing distribution among the population, however, have hampered the control of the virus so far. Methods We propose a new mathematical model to estimate the impact of vaccination delay against the 2019 coronavirus disease (COVID-19) on the number of cases and deaths due to the disease in Brazil. We apply the model to Brazil as a whole and to the State of Sao Paulo, the most affected by COVID-19 in Brazil. We simulated the model for the populations of the State of Sao Paulo and Brazil as a whole, varying the scenarios related to vaccine efficacy and compliance from the populations. Results The model projects that, in the absence of vaccination, almost 170 thousand deaths and more than 350 thousand deaths will occur by the end of 2021 for Sao Paulo and Brazil, respectively. If in contrast, Sao Paulo and Brazil had enough vaccine supply and so started a vaccination campaign in January with the maximum vaccination rate, compliance and efficacy, they could have averted more than 112 thousand deaths and 127 thousand deaths, respectively. In addition, for each month of delay the number of deaths increases monotonically in a logarithmic fashion, for both the State of Sao Paulo and Brazil as a whole. Conclusions Our model shows that the current delay in the vaccination schedules that is observed in many countries has serious consequences in terms of mortality by the disease and should serve as an alert to health authorities to speed the process up such that the highest number of people to be immunized is reached in the shortest period of time.

scholarly journals Adversarial Data Augmentation on Breast MRI Segmentation

2021 ◽  
Vol 11 (10) ◽  
pp. 4554
Author(s):  
João F. Teixeira ◽  
Mariana Dias ◽  
Eva Batista ◽  
Joana Costa ◽  
Luís F. Teixeira ◽  
...  
Keyword(s):  
Data Augmentation ◽  
Medical Image Analysis ◽  
Synthetic Data ◽  
Breast Mri ◽  
Semantic Segmentation ◽  
Adversarial Networks ◽  
Augmentation Strategy ◽  
Magnetic Resonance Imaging Mri ◽  
Segmentation Task ◽  
The Impact

The scarcity of balanced and annotated datasets has been a recurring problem in medical image analysis. Several researchers have tried to fill this gap employing dataset synthesis with adversarial networks (GANs). Breast magnetic resonance imaging (MRI) provides complex, texture-rich medical images, with the same annotation shortage issues, for which, to the best of our knowledge, no previous work tried synthesizing data. Within this context, our work addresses the problem of synthesizing breast MRI images from corresponding annotations and evaluate the impact of this data augmentation strategy on a semantic segmentation task. We explored variations of image-to-image translation using conditional GANs, namely fitting the generator’s architecture with residual blocks and experimenting with cycle consistency approaches. We studied the impact of these changes on visual verisimilarity and how an U-Net segmentation model is affected by the usage of synthetic data. We achieved sufficiently realistic-looking breast MRI images and maintained a stable segmentation score even when completely replacing the dataset with the synthetic set. Our results were promising, especially when concerning to Pix2PixHD and Residual CycleGAN architectures.

scholarly journals Spectral gap in random bipartite biregular graphs and applications

2021 ◽  
pp. 1-39
Author(s):  
Gerandy Brito ◽  
Ioana Dumitriu ◽  
Kameron Decker Harris
Keyword(s):  
Community Detection ◽  
Adjacency Matrix ◽  
Moment Method ◽  
Coding Theory ◽  
High Probability ◽  
Spectral Gap ◽  
Matrix Completion ◽  
Full Rank ◽  
The Moment ◽  
Deterministic Matrix

Abstract We prove an analogue of Alon’s spectral gap conjecture for random bipartite, biregular graphs. We use the Ihara–Bass formula to connect the non-backtracking spectrum to that of the adjacency matrix, employing the moment method to show there exists a spectral gap for the non-backtracking matrix. A by-product of our main theorem is that random rectangular zero-one matrices with fixed row and column sums are full rank with high probability. Finally, we illustrate applications to community detection, coding theory, and deterministic matrix completion.

Investigation of the Thermodynamic Properties of Anharmonic Crystals with Defects and Influence of Anharmonicity in Exafs by the Moment Method

1998 ◽  
Vol 12 (02) ◽  
pp. 191-205 ◽  
Author(s):  
Vu Van Hung ◽  
Nguyen Thanh Hai
Keyword(s):  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Phase Change ◽  
Specific Heat ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Moment Method ◽  
Adiabatic Compressibility ◽  
Relative Displacement ◽  
The Moment

By the moment method established previously on the basis of the statistical mechanics, the thermodynamic properties of a strongly anharmonic face-centered and body-centered cubic crystal with point defect are considered. The thermal expansion coefficient, the specific heat Cv and Cp, the isothermal and adiabatic compressibility, etc. are calculated. Our calculated results of the thermal expansion coefficient, the specific heat Cv and Cp… of W, Nb, Au and Ag metals at various temperatures agrees well with the measured values. The anharmonic effects in extended X-ray absorption fine structure (EXAFS) in the single-shell model are considered. We have obtained a new formula for anharmonic contribution to the mean square relative displacement. The anharmonicity is proportional to the temperature and enters the phase change of EXAFS. Our calculated results of Debye–Waller factor and phase change in EXAFS of Cu at various temperatures agrees well with the measured values.

La structure de classes québécoise au 19e siècle et le problème de l'articulation des modes de production

1981 ◽  
Vol 14 (3) ◽  
pp. 487-518
Author(s):  
Gérald Bernier
Keyword(s):  
Census Data ◽  
New France ◽  
Class Structure ◽  
Capitalist Development ◽  
Single Class ◽  
The Moment ◽  
Empirical Demonstration ◽  
Work Done ◽  
The Impact

The study of social classes in the nineteenth century requires the development of conceptual tools able to explain the impact of the Conquest on the pre-existant social structures in determining transformations of the class structure during the subsequent decades.This article examines the work done on this question by Marxist writers. The author criticizes certain conclusions which have been drawn and which suggest deficiencies at a theoretical level. The objections relate to the marked tendency of these conclusions to perceive the structural effects of the Conquest in terms of the formation of a double-class structure characterized by “ethnic origins.” Specifically, the author challenges the notion of the division itself, as well as the criterion on which the division is based.The author proposes that an analysis centred upon the concepts relating to a problem of the transition and linkage of different modes of production permits a more satisfying interpretation, if accompanied by a certain number of considerations of the “upside” and “downside” of the Conquest. To this end, the argument is based on a characterization of New France in terms of the domination of the relations of production of the feudal type and on an analysis of metropolitan centres with intent to evaluate their level of capitalist development at the moment of their respective colonial penetration in Canada. The results of this approach permit one to posit the existence of a single-class structure, characterized principally by the existence of elements connecting diverse modes and forms of production, whose origin reflects the unequal state of economic development in the two metropolitan centres.The empirical demonstration rests on the census data of 1851–1852 and on the complementary information drawn from the works of historians.

scholarly journals Impact of the COVID-19 Pandemic on the Patient’s Decision about Bariatric Surgery: Results of a National Survey

Medicina ◽  
2021 ◽  
Vol 57 (8) ◽  
pp. 756
Author(s):  
Maciej Walędziak ◽  
Anna Różańska-Walędziak ◽  
Paweł Bartnik ◽  
Joanna Kacperczyk-Bartnik ◽  
Andrzej Kwiatkowski ◽  
...  
Keyword(s):  
Bariatric Surgery ◽  
Online Survey ◽  
Negative Impact ◽  
Weight Loss Surgery ◽  
General Information ◽  
Open Questions ◽  
Increased Risk ◽  
Bariatric Patients ◽  
The Moment ◽  
The Impact

Background: the COVID-19 pandemic and the implemented restrictions have changed the functioning of healthcare systems worldwide. The purpose of the study was to evaluate the impact of the present epidemiological situation on patients’ decisions about undergoing weight loss surgery. Methods: data were collected from 906 bariatric patients by the means of a national online survey, the majority of whom were women (87.9%). The survey started on 9 April 2020 and was open until 28 April 2020. The questionnaire included multiple choice and open questions, divided into three chapters: general information about the patient, life during the COVID-19 pandemic, and bariatric care during the COVID-19 pandemic. Results: despite the pandemic and the associated risk of COVID-19 infection, 443 responders (48.9%) would have decided to undergo bariatric surgery. Awareness of the negative impact of obesity on the course of COVID-19 illness had only marginable impact on patients’ decision-making (76.6% vs. 75.3%; p < 0.80). Contact with COVID-19 prior to the survey had a negative impact on the willingness to undergo bariatric surgery (3.0% vs. 4.4%; p < 0.55). There was a positive correlation between the BMI and preference for bariatric surgery in the time of the pandemic (37.4 ± 9.0 vs. 34.9 ± 8.7; p < 0.001). Conclusions: the level of awareness about the advantages of operative treatment of obesity is high among bariatric patients. The majority of patients awaiting bariatric surgery at the moment of the survey were positive about undergoing bariatric surgery despite the increased risk of a serious course of COVID-19 infection. Therefore, a large proportion of patients was determined to have bariatric treatment even during the pandemic, being aware of the increased risk of worse pace of COVID-19 disease in case of obesity and related diseases.

Road barriers: modern solutions for improving traffic safety

2021 ◽  
pp. 43-48
Author(s):  
Keyword(s):  
Traffic Safety ◽  
Traffic Accident ◽  
Preventive Measures ◽  
Mechanical Damage ◽  
Road Accidents ◽  
Road Users ◽  
Urgent Task ◽  
The Moment ◽  
Energy Absorbing ◽  
The Impact

Improving the system of preventive measures aimed at reducing the severity of the consequences of road accidents is an urgent task. Road deaths are constantly increasing and there is a need for a comprehensive approach to creating safe road conditions. The purpose of this study is to analyze the promising designs of road barriers designed to prevent uncontrolled exit of vehicles from the roadway of the highway and to develop the design of energy-absorbing fencing. Barrier barriers must not only be safe for road users, but must also ensure their safety, as well as preserve the elements after hitting the fence. Analytical studies have shown that in order to reduce mechanical damage to vehicles and reduce the severity of injuries to the driver and passengers, it is necessary to develop a road fence design that allows you to extinguish the impact energy at the moment of contact between the car and the fence. Keywords: fencing, barrier, safety, traffic accident

Sign in / Sign up

Export Citation Format

Share Document