scholarly journals Morphology analysis of tracks in the aerogels impacted by hypervelocity irregular particles

2021 ◽  
Vol 9 ◽  
Author(s):  
Ai Du ◽  
Yi Ma ◽  
Mingfang Liu ◽  
Zhihua Zhang ◽  
Guangwei Cao ◽  
...  
Keyword(s):  
Direct Evidence ◽  
Outer Space ◽  
Silica Aerogels ◽  
Track Length ◽  
Laser Shock ◽  
Penetration Process ◽  
Experimental Parameters ◽  
Entrance Hole ◽  
The Impact ◽  
Impact Experiments

Abstract As an attractive collector medium for hypervelocity particles, combined with outstanding physical properties and suitable compositional characteristics, SiO2 aerogel has been deployed on outer space missions and laser shock-loaded collection experiments. In this paper, impact experiments were conducted to understand the penetration process of irregular grains, irregular Al2O3 grains with two different sizes and speeds (~110 μm@7 km/s, ~251 μ[email protected] km/s) at various density silica aerogels. By classifying the shapes of projectile residues and tracks, the morphology of tracks was analyzed. It was observed that there were several kinds of typical tracks in the penetration of irregular grains, accompanied by residues with the shapes of near-sphere, polyhedron, streamlined body wedge, and rotator. The rotational behavior was demonstrated by the final status of one flake projectile as direct evidence. In addition, there was no obvious relationship between the track length and experimental parameters, which may be caused by the uncertain interaction between aerogels and irregular particles. In addition, it confirmed the existence of fragmentation, melting situation by observing the shape of the impact entrance hole. At the same time, optical coherence tomography was used to observe the detail of tracks clearly, which provided a method to characterize the tracks nondestructively.

scholarly journals Study on performance degradation and damage modes of thin-film photovoltaic cell subjected to particle impact

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kailu Xiao ◽  
Xianqian Wu ◽  
Xuan Song ◽  
Jianhua Yuan ◽  
Wenyu Bai ◽  
...  
Keyword(s):  
Impact Velocity ◽  
Conversion Efficiency ◽  
Photovoltaic Cell ◽  
Performance Degradation ◽  
Particle Impact ◽  
Laser Shock ◽  
Number Density ◽  
Mechanical Modeling ◽  
The Impact ◽  
Impact Experiments

AbstractIt has been a key issue for photovoltaic (PV) cells to survive under mechanical impacts by tiny dust. In this paper, the performance degradation and the damage behavior of PV cells subjected to massive dust impact are investigated using laser-shock driven particle impact experiments and mechanical modeling. The results show that the light-electricity conversion efficiency of the PV cells decreases with increasing the impact velocity and the particles’ number density. It drops from 26.7 to 3.9% with increasing the impact velocity from 40 to 185 m/s and the particles’ number densities from 35 to 150/mm2, showing a reduction up to 85.7% when being compared with the intact ones with the light-electricity conversion efficiency of 27.2%. A damage-induced conversion efficiency degradation (DCED) model is developed and validated by experiments, providing an effective method in predicting the performance degradation of PV cells under various dust impact conditions. Moreover, three damage modes, including damaged conducting grid lines, fractured PV cell surfaces, and the bending effects after impact are observed, and the corresponding strength of each mode is quantified by different mechanical theories.

scholarly journals A flexible ChIP-sequencing simulation toolkit

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
An Zheng ◽  
Michael Lamkin ◽  
Yutong Qiu ◽  
Kevin Ren ◽  
Alon Goren ◽  
...  
Keyword(s):  
Ground Truth ◽  
Peak Calling ◽  
Simulation Framework ◽  
Experimental Conditions ◽  
Ground Truth Data ◽  
Chip Sequencing ◽  
Genome Wide ◽  
Experimental Parameters ◽  
Differential Binding ◽  
The Impact

Abstract Background A major challenge in evaluating quantitative ChIP-seq analyses, such as peak calling and differential binding, is a lack of reliable ground truth data. Accurate simulation of ChIP-seq data can mitigate this challenge, but existing frameworks are either too cumbersome to apply genome-wide or unable to model a number of important experimental conditions in ChIP-seq. Results We present ChIPs, a toolkit for rapidly simulating ChIP-seq data using statistical models of key experimental steps. We demonstrate how ChIPs can be used for a range of applications, including benchmarking analysis tools and evaluating the impact of various experimental parameters. ChIPs is implemented as a standalone command-line program written in C++ and is available from https://github.com/gymreklab/chips. Conclusions ChIPs is an efficient ChIP-seq simulation framework that generates realistic datasets over a flexible range of experimental conditions. It can serve as an important component in various ChIP-seq analyses where ground truth data are needed.

scholarly journals Direct Evidence Versus Lack of Direct Evidence and the Impact on HTA Acceptance

2015 ◽  
Vol 18 (7) ◽  
pp. A557
Author(s):  
EA Griffiths ◽  
FR Sheppard ◽  
S Pathak ◽  
J Hendrich ◽  
RL Martin ◽  
...  
Keyword(s):  
Direct Evidence ◽  
The Impact

Experimental Research on the Vibration Reduction and Impact Resistance Performances of Offshore Structure Based on Magnetorheological Damper

2008 ◽  
Author(s):  
Zhongchao Deng ◽  
Dagang Zhang ◽  
Xiongliang Yao
Keyword(s):  
Vibration Reduction ◽  
Impact Resistance ◽  
Mr Damper ◽  
Magnetorheological Damper ◽  
Offshore Structure ◽  
Loading System ◽  
Vibration Experiment ◽  
Exciting Forces ◽  
The Impact ◽  
Impact Experiments

This paper presents a new kind of vibration reduction and impact resistance isolator system based on magnetorheological technique, and its experiment results. The vibration and impact experiments were designed using MTS hydraulic loading system. There were many load cases being applied in the experiment with different mass of the model, exciting forces, and controllable electricity of MR damper (Magnetorheological Damper). The experiment results indicate that this isolator system can control the vibration response very well, especially near the natural frequency of the system; and the isolator system has a good performance in the impact experiment too, the response acceleration was evidently reduced, but the characteristic of MR damper was different form its performance in vibration experiment.

Effects of CSF Properties on Brain Response Under Impact Loading

2009 ◽  
Author(s):  
M. S. Chafi ◽  
V. Dirisala ◽  
G. Karami ◽  
M. Ziejewski
Keyword(s):  
Human Head ◽  
Brain Response ◽  
Pia Mater ◽  
Mechanical Shocks ◽  
The Central Nervous System ◽  
Simultaneous Loading ◽  
The Impact ◽  
Impact Experiments ◽  
The Brain

In the central nervous system, the subarachnoid space is the interval between the arachnoid membrane and the pia mater. It is filled with a clear, watery liquid called cerebrospinal fluid (CSF). The CSF buffers the brain against mechanical shocks and creates buoyancy to protect it from the forces of gravity. The relative motion of the brain due to a simultaneous loading is caused because the skull and brain have different densities and the CSF surrounds the brain. The impact experiments are usually carried out on cadavers with no CSF included because of the autolysis. Even in the cadaveric head impact experiments by Hardy et al. [1], where the specimens are repressurized using artificial CSF, this is not known how far this can replicate the real functionality of CSF. With such motivation, a special interest lies on how to model this feature in a finite element (FE) modeling of the human head because it is questionable if one uses in vivo CSF properties (i.e. bulk modulus of 2.19 GPa) to validate a FE human head against cadaveric experimental data.

scholarly journals Uptake of p-Nitrophenol (PNP) from model aqueous solutions using raw and quaternised Afromomum melegueta peels

2020 ◽  
Vol 1 (1) ◽  
pp. 1-8
Author(s):  
J. Ndiritu ◽  
I W. Mwangi ◽  
J. I. Murungi ◽  
R. N. Wanjau
Keyword(s):  
Quaternary Ammonium ◽  
Anthropogenic Activities ◽  
Freundlich Isotherm ◽  
Isotherm Models ◽  
Ammonium Compound ◽  
Cellulose Structure ◽  
Experimental Parameters ◽  
Ftir Technique ◽  
Design Simplicity ◽  
The Impact

 Anthropogenic activities contribute large amounts of pollutants to the environment which threaten animal and human health. There is increased realization of the effect of these toxins on surface and ground water, consequently, their elimination is vital in rendering secure water for drinking as well as culpable release of effluents to our habitats. Phenolic compounds cause serious health effects to both humans and animals; a p-Nitrophenol concentration of 1 ppb changes the taste and odour of water as well as meat and fish quality. In humans, exposure to PNP causes eye and skin burns while its interaction with blood leads to confusion, cyanosis and unconsciousness. It is imperative therefore to find ways for removing PNP from water. Among the available techniques for removing PNP from water, adsorption is more convenient and offers more advantages because of its design, simplicity, and operating flexibility. The present study involved application of peels of raw Afromomum melegueta (RAM) and quaternised Afromomum melegueta (QAM) to remove PNP from water through adsorption. The raw adsorbents were modified with a quaternary ammonium salt to improve their uptake efficiency. The impact of experimental parameters; contact time, pH, sorbent dose, temperature and concentration were investigated. Attenuated FTIR technique was employed to characterize the adsorbent materials. It was established that the quaternary ammonium compound was anchored chemically within the cellulose structure of Afromomum melegueta peels. The behavior of adsorption of PNP was investigated using Langmuir and Freundlich isotherm models. The physical sorption load was 8.70 and 106.38 mg/g for RAM and QAM peels respectively from Langmuir adsorption equation. Uptake of PNP is high at the first 30 mins of contact and at sorbent dosage of 0.01 g and 0.03 g for RAM and QAM respectively. Quantity of PNP removed increases as the initial concentration rises however, adsorption decreases after a concentration exceeding 30 mg/L. The ideal pH and temperature for PNP removal is at pH 3 and 25 ˚C respectively. In conclusion, the findings suggest that Afromomum melegueta peels can be friendly to the environment, cheap biosorbents and efficient which can be applied for the uptake of PNP from drinking water

The impact of the information factor on modern international relations

2021 ◽  
Vol 62 (01) ◽  
pp. 141-146
Author(s):  
Gulnaz Tahir Hasanova ◽  
Keyword(s):  
International Relations ◽  
Outer Space ◽  
Cyber Attacks ◽  
The Internet ◽  
Information Warfare ◽  
Fake News ◽  
False Information ◽  
Fifth Dimension ◽  
Private Actors ◽  
The Impact

This study aims to highlight the growing strategic importance that cyberspace is gaining in the dynamics of international politics. After land, sea, air, and outer space, cyberspace is the fifth dimension of conflict. The type of non-military weapons used to fight, as well as the subjects targeted, make civilian systems new centers of gravity to defend against an enemy that most often "operates in the shadows." The international scenario rmation revolution (which contributed to the "democratization of information"), is radically evolving from a unipolar (American-led) to an almost multipolar architecture. The Internet today is an indispensable communication and information network for various legal and illegal subjects of international relations. Social networks (Facebook, Twitter, Telegram) play a very important role in this process. The Internet can also allow manipulation or even destabilization of the international community with the spread of false information (fake news). It is also a field for intelligence activities. Finally, the Internet is becoming the field of a new form of confrontation. Thus, both states and private actors protect themselves from possible cyber attacks by developing cybersecurity. In anticipation of this, states are developing cyberspace strategies and military-digital capabilities. Key words: international relations, information, cyberspace, cybersecurity, territorial integrity, state, subjects of international relations, information warfare

Analysis of hypervelocity impacts: The tungsten case

2021 ◽  
Author(s):  
A Fraile ◽  
Prashant Dwivedi ◽  
Giovanni Bonny ◽  
Tomas Polcar
Keyword(s):  
Kinetic Energy ◽  
Interatomic Potential ◽  
Detailed Examination ◽  
Penetration Process ◽  
Damage Initiation ◽  
Crater Size ◽  
Crater Volume ◽  
Parallel Molecular Dynamics ◽  
Dynamics Simulations ◽  
The Impact

Abstract The atomistic mechanisms of damage initiation during high velocity (v up to 9 km/s, kinetic energies up to 200 keV) impacts of W projectiles on a W surface have been investigated using parallel molecular-dynamics simulations involving large samples (up to 40 million atoms). Various aspects of the impact at high velocities, where the projectile and part of the target materials undergo massive plastic deformation, breakup, melting, and vaporization, are analyzed. Different stages of the penetration process have been identified through a detailed examination of implantation, crater size and volume, sputtered atoms, and dislocations created by the impacts. The crater volume increases linearly with the kinetic energy for a given impactor; and the total dislocation length increases with the kinetic energy but depends itself on the size of the impactor. Furthermore, the total dislocation length is less dependent of the fine details of the interatomic potential. The results are rationalized based on the physical properties of bcc W.

A review of treatment plans for the biological clock of astronauts: A systematic review

2021 ◽  
Vol 2 (2) ◽  
pp. 007-015
Author(s):  
Shohreh Ghasemi ◽  
Reyhaneh Heydari ◽  
Faranak goodarzi ◽  
Fargol Mashhadi Akbar Boojar ◽  
Amirreza Dashti ◽  
...  
Keyword(s):  
Adverse Effects ◽  
Sleep Disorders ◽  
Outer Space ◽  
Biological Clock ◽  
Microgravity Environment ◽  
Space Travel ◽  
Long Term Effects ◽  
Pubmed Database ◽  
Sleep Deficiency ◽  
The Impact

Since the start of civilization and even further back, humankind has been dreaming of flying. Recently, this dream has come true and reached beyond that and sends astronauts to outer space. However, by achieving this milestone, we encountered new problems that were new to humanity. One of the biggest problems is having a sleeping disorder and disruption of the biological clock. It is essential because having a sleep disorder makes astronauts unable to function at 100% capacity, and in outer space, it is dangerous. Some treatments for sleep disorders include drug therapy, such as Dexedrine, temazepam, modafinil, bupropion, melatonin, zolpidem, dextroamphetamine, light treatment, or a trickling sleep/wake schedule, according to NASA's guidelines. This study aimed to review the treatments for sleep disorders and disruption of the biological clock aimed at astronauts during space flights. We presented the different treatments and discussed and oriented the next prospect of research on sleep in space. Therefore, there will be guidelines for astronauts during their flights. Since the beginning of space travel, there have been many papers regarding space and weightlessness on the adverse effects on health. Studies have described the effect of space travel and the environment of microgravity on health. A few studies include both the short- and long-term effects of microgravity on the biological clock. With this new dawn and sending new astronauts to International Space Station (ISS) with NASA and SpaceX commercial Falcon 9 rocket, which opened a new horizon for spaceflights, it is even more important to consider the adverse effects microgravity on health. Purpose: This review aims to specifically analyze the biological clock, sleep deficiency, and circadian disorders. As we acknowledge, there is a sleep deficiency associated with complex microgravity environs and space missions before and after launch. Material and methods: Two researchers searched a thorough and detailed search of the PubMed database with the keywords mentioned below. The search was performed in November 2020 without any time limitations. We only included human studies and articles in the English language. Results: A total of 148 articles were found, and after going through titles, 77 articles were chosen for checking abstracts. Finally, only 12 manuscripts were accepted for data extraction. Conclusion: It is essential for health care involved in space travel providers to help pre-emptively identify problems that may prevent severe consequences during a microgravity environment. Sleep and circadian factors are the fundamental issues of human fatigue, and aviation schedules significantly impact both. We should admire a computerized fatigue model for having a better approach to studying the impact of scheduling.

scholarly journals Instrumental and ethical aspects of experimental research with animal models

2014 ◽  
Vol 48 (1) ◽  
pp. 177-183 ◽  
Author(s):  
Mirian Watanabe ◽  
Cassiane Dezoti da Fonseca ◽  
Maria de Fatima Fernandes Vattimo
Keyword(s):  
Animal Models ◽  
Experimental Research ◽  
Nursing Care ◽  
Ethics Committees ◽  
Clinical Aspect ◽  
Quality Data ◽  
Ethical Aspects ◽  
Current State ◽  
Experimental Parameters ◽  
The Impact

Experimental animal models offer possibilities of physiology knowledge, pathogenesis of disease and action of drugs that are directly related to quality nursing care. This integrative review describes the current state of the instrumental and ethical aspects of experimental research with animal models, including the main recommendations of ethics committees that focus on animal welfare and raises questions about the impact of their findings in nursing care. Data show that, in Brazil, the progress in ethics for the use of animals for scientific purposes was consolidated with Law No. 11.794/2008 establishing ethical procedures, attending health, genetic and experimental parameters. The application of ethics in handling of animals for scientific and educational purposes and obtaining consistent and quality data brings unquestionable contributions to the nurse, as they offer subsidies to relate pathophysiological mechanisms and the clinical aspect on the patient.

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