scholarly journals Modeling of Spherical Dust Particle Charging due to Ion Attachment

2021 ◽  
Vol 9 ◽  
Author(s):  
Sotirios A. Mallios ◽  
Georgios Papangelis ◽  
George Hloupis ◽  
Athanasios Papaioannou ◽  
Vasiliki Daskalopoulou ◽  
...  
Keyword(s):  
Electric Field ◽  
Large Scale ◽  
Negative Ions ◽  
Particle Dynamics ◽  
Electrical Charge ◽  
Dust Particles ◽  
Electrical Force ◽  
Force Magnitude ◽  
Ion Attachment ◽  
The Impact

The attachment of positive and negative ions to settling spherical dust particles is studied. A novel 1D numerical model has been developed to parameterize the charging process in the presence of a large-scale electric field. The model is able to self-consistently calculate the modification of atmospheric ion densities in the presence of the dust particles, and the consequent alteration of the atmospheric electrical conductivity and the large-scale electric field. Moreover, the model estimates the acquired electrical charge on the dust particles and calculates the electrical force that is applied on them. Using observed dust size distributions, we find that the particles can acquire electrical charge in the range of 1–1,000 elementary charges depending on their size and number density. The particles become mainly negatively charged, but under specific conditions giant mode particles (larger than 50 μm radius) can be positive. Moreover, the large-scale electric field can increase up to 20 times as much as the fair weather value. However, our approach shows that the resultant electrical force is not enough to significantly influence their gravitational settling, as the ratio between the electrical force magnitude and the gravity magnitude does not exceed the value of 0.01. This indicates that the process of ion attachment alone is not sufficient to create strong electrical effects for the modification of particle dynamics. Therefore, other processes, such as the triboelectric effect and updrafts, must be included in the model to fully represent the impact of electricity on particle dynamics.

The Effective Temperature of Dust Impact Plasmas — Olivine Dust on Tungsten Target

2021 ◽  
Author(s):  
Jiří Pavlů ◽  
Samuel Kočiščák ◽  
Åshild Fredriksen ◽  
Michael DeLuca ◽  
Zoltan Sternovsky
Keyword(s):  
Negative Charge ◽  
Negative Ions ◽  
Charge Carriers ◽  
Dust Particles ◽  
Applied Bias ◽  
Control Grid ◽  
Impact Speed ◽  
Positive Ions ◽  
Effective Temperatures ◽  
The Impact

<p>We experimentally observe both positive and negative charge carriers in impact plasma and estimate their effective temperatures. The measurements are carried on a dust accelerator using polypyrrole (PPy)-coated olivine dust particles impacting tungsten (W) target in the velocity range of 2–18 km/s. We measure the retained impact charge as a function of applied bias potential to the control grid. The temperatures are estimated from the data fit. The estimated effective temperatures of the positive ions are approximately 7 eV and seems to be independent of the impact speed. The negative charge carriers' temperatures vary from as low as 1 eV for the lowest speeds to almost ten times higher speeds. The presented values differ significantly from previous studies using Fe dust particles. Yet, the discrepancy can be attributed to a larger fraction of negative ions in the impact plasma that likely originates from the PPy coating.</p>

A 3D Time-Dependent Model for the Study of the Electrification of Non Spherical Dust Particles due to Ion Attachment

2020 ◽  
Author(s):  
Sotirios Mallios ◽  
Vasiliki Daskalopoulou ◽  
Evangelos Skoubris ◽  
George Hloupis ◽  
Athanasios Papaioannou ◽  
...  
Keyword(s):  
Electric Field ◽  
Dust Cloud ◽  
Dust Particles ◽  
Dust Layer ◽  
The Past ◽  
Dependent Model ◽  
Ion Attachment ◽  
Atmospheric Conductivity ◽  
Time Dependent Model ◽  
Positively Charged

<p>Electrical processes can be a potential key player in the lifecycle of desert dust. The dust particles can be charged during their transport, either by the attachment of atmospheric ions or by particle to particle collisions (triboelectric effect). Measurements indicate that, on average, larger particles become positively charged while the smaller ones become negatively charged [<em>Zhao, H. L.</em>, J. Electrostat, 55, 2002; <em>Lacks, D.J.</em>, et al., Phys. Rev. Lett., 100, 188305, 2008; <em>Merrison, J.P.</em>, Aeolian Res., 4, 2012; <em>Shinbrot, T. and Herrmann, H.J.</em>, Nature, 451, 2008]. During dust transportation, the larger and mainly positively charged particles separate from the smaller negatively charged particles due to the gravitational sedimentation, which sorts the dust particles by size. This process develops vertical electric fields within the dust cloud, enhancing the pre-existing field due to the depletion of atmospheric conductivity by the presence of the dust layer [<em>Gringel W. and Mulheisen. R.</em>, Beitr. Phys. Atmos., 51, 121–8, 1978]. Depending on its strength, the total electric field within the dust cloud can: (a) counteract the gravitational settling of large particles and (b) cause a preferential orientation of the non-spherical particles along the vertical direction affecting particle aerodynamics [<em>Ulanowski, Z., et al.</em>, Atmos. Chem. Phys., 7, 2007]. Therefore, electrical processes may alter dust removal processes, and thus the evolution of particle size during transport, affecting dust-radiation-cloud interactions and the associated air quality [<em>Sajani S.Z., et al.</em>, Occup. Environ. Med., 68(6), 2011], weather, and climate modeling [<em>Mahowald, N., et al.</em>, Aeolian Res., 15, 2014].</p><p>In the present work, we have developed a novel 3D Cartesian time-dependent model that takes into account several atmospheric processes, such as: (i) the ionization due to the galactic cosmic rays radiation, (ii) the ion-ion recombination, and (iii) the ion attachment to non spherical dust particles.  The model is able to self-consistently calculate the time dynamics of the atmospheric conductivity, and the atmospheric electric field, under the presence of a distribution of stationary non spherical dust particles. Additionally, the total charge density, dust particle charge and dust particle orientation are also quantified. The new 3D electrification formalism allows the study of dust layers without imposing any symmetry and  is valid for layers with any horizontal and vertical extend, as opposed to 1D models which are valid when the horizontal extend is much larger than the vertical, or to 2D models which assume a symmetry in the shape of the dust layer. The results are compared, in the limiting case that the horizontal extend is much larger than the vertical one, with those obtained from 1D models found in the past literature [e.g. <em>Zhou, L., Tinsley, B.A.</em>, Adv. Space Res. 50, 2012]. Moreover, the effect of the studied electrification process is assessed through a comparison with recent and unique electric field measurements within lofted dust layers, as performed with the use of novel low cost atmospheric electricity sensors in an experimental campaign of the D-TECT ERC project, in Cyprus the past November.</p>

scholarly journals Kinetic-Monte-Carlo-Based Parallel Evolution Simulation Algorithm of Dust Particles

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Xiaomei Hu ◽  
Zhifeng Xu ◽  
Hongxia Cai ◽  
Junjun Hu
Keyword(s):  
Parallel Algorithm ◽  
Large Scale ◽  
Kinetic Monte Carlo ◽  
Parallel Evolution ◽  
Data Distribution ◽  
Dust Particles ◽  
Simulation Algorithm ◽  
Evolution Simulation ◽  
The Impact ◽  
Simulation Time

The evolution simulation of dust particles provides an important way to analyze the impact of dust on the environment. KMC-based parallel algorithm is proposed to simulate the evolution of dust particles. In the parallel evolution simulation algorithm of dust particles, data distribution way and communication optimizing strategy are raised to balance the load of every process and reduce the communication expense among processes. The experimental results show that the simulation of diffusion, sediment, and resuspension of dust particles in virtual campus is realized and the simulation time is shortened by parallel algorithm, which makes up for the shortage of serial computing and makes the simulation of large-scale virtual environment possible.

scholarly journals Measurement of Dust Electric Charges by the Ulysses and Galileo Dust Detectors

1996 ◽  
Vol 150 ◽  
pp. 481-484 ◽  
Author(s):  
J. Svestka ◽  
S. Auer ◽  
M. Baguhl ◽  
E. Grün
Keyword(s):  
Electric Field ◽  
Dust Particle ◽  
Time Of Flight ◽  
Opposite Polarity ◽  
Dust Particles ◽  
Impact Speed ◽  
The Impact

The Galileo and Ulysses dust detectors can detect electric charges of dust particles. Dust particles entering the sensor (see, e.g., Grün et al. 1992) may be detected by the charge Qp that they induce to the charge grid. All suitably massive dust particles - charged or uncharged - are then detected by the cloud of ions and electrons they produce during the impact on the hemispherical target after the time of flight between the charge grid and the target. After separation in the electric field, ions and electrons are collected by separate electrodes and produce two pulses of opposite polarity. From the two pulse heights and the rise times, the mass and impact speed of the dust particle are derived.

scholarly journals Positive and negative role of negative ions in cosmic exploration

2021 ◽  
Vol 69 (3) ◽  
pp. 607-637
Author(s):  
Leonid Gretchikhin
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Negative Ions ◽  
Dust Particles ◽  
Compression Waves ◽  
A Value ◽  
Negative Role ◽  
Small Parts ◽  
The Impact

Introduction/purpose: At altitudes of 80 to 40 km, while the spacecraft made of duralumin without a thermal-protective coating was descending from the flight orbit at the first and second cosmic velocities, data were obtained on the increase in density, pressure, and temperature behind the shock front, as well as on the backout of the shock wave from the surface of the descending spacecraft. Methods: Calculations were made of the energy fluxes on the surface of the spacecraft for every 10 km, for convective and radiative heat transfer, as well as for the impact of electrons produced due to ionization of negative ions. Results: At the first cosmic velocity, the greatest energy flux is realized under the influence of an electron flux, and at the second cosmic velocity, radiative heat transfer occurs. In the shock-compressed gas at all the considered altitudes, pressure increases instantly to a value of 109 ÷ 1011 Pa, which leads to a sequential explosion with increasing power resulting in shock waves in the surrounding atmosphere and compression waves in the entire aircraft structure. The last most powerful explosion occurs at an altitude of approx. 40 km. Conclusion: The descending aircraft is destroyed into separate small parts to the size of small dust particles.

Impact of COVID-19 on Nuclear Medicine in Germany, Austria and Switzerland: An International Survey in April 2020

2020 ◽  
Vol 59 (04) ◽  
pp. 294-299 ◽  
Author(s):  
Lutz S. Freudenberg ◽  
Ulf Dittmer ◽  
Ken Herrmann
Keyword(s):  
Nuclear Medicine ◽  
Health Systems ◽  
Personal Protective Equipment ◽  
Large Scale ◽  
Diagnostic Procedures ◽  
Protective Equipment ◽  
Current Crisis ◽  
Web Based ◽  
Public Versus Private ◽  
The Impact

Abstract Introduction Preparations of health systems to accommodate large number of severely ill COVID-19 patients in March/April 2020 has a significant impact on nuclear medicine departments. Materials and Methods A web-based questionnaire was designed to differentiate the impact of the pandemic on inpatient and outpatient nuclear medicine operations and on public versus private health systems, respectively. Questions were addressing the following issues: impact on nuclear medicine diagnostics and therapy, use of recommendations, personal protective equipment, and organizational adaptations. The survey was available for 6 days and closed on April 20, 2020. Results 113 complete responses were recorded. Nearly all participants (97 %) report a decline of nuclear medicine diagnostic procedures. The mean reduction in the last three weeks for PET/CT, scintigraphies of bone, myocardium, lung thyroid, sentinel lymph-node are –14.4 %, –47.2 %, –47.5 %, –40.7 %, –58.4 %, and –25.2 % respectively. Furthermore, 76 % of the participants report a reduction in therapies especially for benign thyroid disease (-41.8 %) and radiosynoviorthesis (–53.8 %) while tumor therapies remained mainly stable. 48 % of the participants report a shortage of personal protective equipment. Conclusions Nuclear medicine services are notably reduced 3 weeks after the SARS-CoV-2 pandemic reached Germany, Austria and Switzerland on a large scale. We must be aware that the current crisis will also have a significant economic impact on the healthcare system. As the survey cannot adapt to daily dynamic changes in priorities, it serves as a first snapshot requiring follow-up studies and comparisons with other countries and regions.

HOME VISITS DURING THE FIRST MONTH OF DELIVERY FOR RECENTLY DELIVERED WOMEN IN UTTAR PRADESH, INDIA

2020 ◽  
Vol 6 (5) ◽  
pp. 1183-1189
Author(s):  
Dr. Tridibesh Tripathy ◽  
Dr. Umakant Prusty ◽  
Dr. Chintamani Nayak ◽  
Dr. Rakesh Dwivedi ◽  
Dr. Mohini Gautam
Keyword(s):  
Large Scale ◽  
National Level ◽  
Uttar Pradesh ◽  
Life Time ◽  
Structured Interview ◽  
The Other ◽  
Registration System ◽  
Action Group ◽  
Current Article ◽  
The Impact

The current article of Uttar Pradesh (UP) is about the ASHAs who are the daughters-in-law of a family that resides in the same community that they serve as the grassroots health worker since 2005 when the NRHM was introduced in the Empowered Action Group (EAG) states. UP is one such Empowered Action Group (EAG) state. The current study explores the actual responses of Recently Delivered Women (RDW) on their visits during the first month of their recent delivery. From the catchment area of each of the 250 ASHAs, two RDWs were selected who had a child in the age group of 3 to 6 months during the survey. The response profiles of the RDWs on the post- delivery first month visits are dwelled upon to evolve a picture representing the entire state of UP. The relevance of the study assumes significance as detailed data on the modalities of postnatal visits are available but not exclusively for the first month period of their recent delivery. The details of the post-delivery first month period related visits are not available even in large scale surveys like National Family Health Survey 4 done in 2015-16. The current study gives an insight in to these visits with a five-point approach i.e. type of personnel doing the visit, frequency of the visits, visits done in a particular week from among those four weeks separately for the three visits separately. The current study is basically regarding the summary of this Penta approach for the post- delivery one-month period.     The first month period after each delivery deals with 70% of the time of the postnatal period & the entire neonatal period. Therefore, it does impact the Maternal Mortality Rate & Ratio (MMR) & the Neonatal Mortality Rates (NMR) in India and especially in UP through the unsafe Maternal & Neonatal practices in the first month period after delivery. The current MM Rate of UP is 20.1 & MM Ratio is 216 whereas the MM ratio is 122 in India (SRS, 2019). The Sample Registration System (SRS) report also mentions that the Life Time Risk (LTR) of a woman in pregnancy is 0.7% which is the highest in the nation (SRS, 2019). This means it is very risky to give birth in UP in comparison to other regions in the country (SRS, 2019). This risk is at the peak in the first month period after each delivery. Similarly, the current NMR in India is 23 per 1000 livebirths (UNIGME,2018). As NMR data is not available separately for states, the national level data also hold good for the states and that’s how for the state of UP as well. These mortalities are the impact indicators and such indicators can be reduced through long drawn processes that includes effective and timely visits to RDWs especially in the first month period after delivery. This would help in making their post-natal & neonatal stage safe. This is the area of post-delivery first month visit profile detailing that the current article helps in popping out in relation to the recent delivery of the respondents.   A total of four districts of Uttar Pradesh were selected purposively for the study and the data collection was conducted in the villages of the respective districts with the help of a pre-tested structured interview schedule with both close-ended and open-ended questions.  The current article deals with five close ended questions with options, two for the type of personnel & frequency while the other three are for each of the three visits in the first month after the recent delivery of respondents. In addition, in-depth interviews were also conducted amongst the RDWs and a total 500 respondents had participated in the study.   Among the districts related to this article, the results showed that ASHA was the type of personnel who did the majority of visits in all the four districts. On the other hand, 25-40% of RDWs in all the 4 districts replied that they did not receive any visit within the first month of their recent delivery. Regarding frequency, most of the RDWs in all the 4 districts received 1-2 times visits by ASHAs.   Regarding the first visit, it was found that the ASHAs of Barabanki and Gonda visited less percentage of RDWs in the first week after delivery. Similarly, the second visit revealed that about 1.2% RDWs in Banda district could not recall about the visit. Further on the second visit, the RDWs responded that most of them in 3 districts except Gonda district did receive the second postnatal visit in 7-15 days after their recent delivery. Less than half of RDWs in Barabanki district & just more than half of RDWs in Gonda district received the third visit in 15-21 days period after delivery. For the same period, the majority of RDWs in the rest two districts responded that they had been entertained through a home visit.

The Impact of Quantitative Easing on Emerging Markets – Literature Review

e-Finanse ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 67-76
Author(s):  
Piotr Bartkiewicz
Keyword(s):  
Emerging Markets ◽  
Large Scale ◽  
Empirical Literature ◽  
Quantitative Easing ◽  
Methodological Choices ◽  
The Subject ◽  
Methodological Approaches ◽  
The Impact ◽  
Sufficient Precision

AbstractThe article presents the results of the review of the empirical literature regarding the impact of quantitative easing (QE) on emerging markets (EMs). The subject is of interest to policymakers and researchers due to the increasingly larger role of EMs in the world economy and the large-scale capital flows occurring after 2009. The review is conducted in a systematic manner and takes into consideration different methodological choices, samples and measurement issues. The paper puts the summarized results in the context of transmission channels identified in the literature. There are few distinct methodological approaches present in the literature. While there is a consensus regarding the direction of the impact of QE on EMs, its size and durability have not yet been assessed with sufficient precision. In addition, there are clear gaps in the empirical findings, not least related to relative underrepresentation of the CEE region (in particular, Poland).

Numerical Simulation of Leakage Current on Conductive Insulator Surface

2019 ◽  
Vol 8 (4) ◽  
pp. 9487-9492
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Leakage Current ◽  
Method Of Lines ◽  
Electron Attachment ◽  
Negative Ions ◽  
Conduction Current ◽  
Insulator Surface ◽  
Finite Difference Approximations ◽  
Positive Ions

The outdoor insulator is commonly exposed to environmental pollution. The presence of water like raindrops and dew on the contaminant surface can lead to surface degradation due to leakage current. However, the physical process of this phenomenon is not well understood. Hence, in this study we develop a mathematical model of leakage current on the outdoor insulator surface using the Nernst Planck theory which accounts for the charge transport between the electrodes (negative and positive electrode) and charge generation mechanism. Meanwhile the electric field obeys Poisson’s equation. Method of Lines technique is used to solve the model numerically in which it converts the PDE into a system of ODEs by Finite Difference Approximations. The numerical simulation compares reasonably well with the experimental conduction current. The findings from the simulation shows that the conduction current is affected by the electric field distribution and charge concentration. The rise of the conduction current is due to the distribution of positive ion while the dominancy of electron attachment with neutral molecule and recombination with positive ions has caused a significant reduction of electron and increment of negative ions.

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