Different Types Of Surfaces Research Articles

Hollow droplet impact on a solid surface

Droplet impact on a solid surface occurs in many natural phenomena and industrial applications such as raindrop impact on the ground, drip irrigation, spray cooling, spray coating, inkjet printing, etc. Importantly, in several cases such as aerosol transfer from the sea, oxygen dissolution, and thermally sprayed coatings the impinging droplets contain air bubble dealing with liquid-bubble-solid interaction. These hollow droplets upon impacting on the target surface, due to their controllable weight and embedded medium, control the splat properties by triggering the cavitation and releasing the inner substance. To better understand the flattening process of a hollow droplet, in this work a comprehensive experimental and numerical study is performed on water and glycerol droplets impacting on a rigid surface. The experiments are repeated on different types of surfaces including aluminum, sand-blasted steel, and superhydrophobic. The results show that the mechanisms of the post-impact process of hollow droplets are different from those of dense droplets in several aspects. We study the role of surface wettability, liquid properties, and impact velocity on the droplet flattening process. In the numerical work, we compare pressure contours and velocity vectors for dense and hollow droplets that provide an in-depth insight through the formation of splat and counter jets.

REVIEW OF HIGH-RESOLUTION GLOBAL LAND COVER

Abstract. The land cover detection on our planet at high spatial resolution has a key role in many scientific and operational applications, such as climate modeling, natural resources management, biodiversity studies, urbanization analyses and spatial demography. Thanks to the progresses in Remote Sensing, accurate and high-resolution land cover maps have been developed over the last years, aiming at detecting the spatial resolution of different types of surfaces. In this paper we propose a review of the high-resolution global land cover products developed through Earth Observation technologies. A series of general information regarding imagery and data used to produce the map, the procedures employed for the map development and for the map accuracy assessment have been provided for every dataset. The land cover maps described in this paper concern the global distribution of settlements (Global Urban Footprint, Global Human Settlement Built-Up, World Settlement Footprint), water (Global Surface Water), forests (Forest/Non-forest, Tree canopy cover), and a two land cover maps describing world in 10 generic classes (GlobeLand30 and Finer Resolution Observation and Monitoring of Global Land Cover). The advantages and shortcomings of these maps and of the methods employed to produce them are summarized and compared in the conclusions.

Экспериментальные исследования силы сцепления стальной оцинкованной пластины и бетона

Introduction. The co-authors present the findings of experimental studies of the adhesion force arising between a zinc-coated steel plate and concrete. Four specimens were used in testing. Rectangular plates, embedded in a concrete parallelepiped, had different types of surfaces. They were smooth, perforated with holes, or they had connecting elements such as bolts or spikes. The behavior of specimens under loading is analyzed; graphs, describing the dependency between displacements and loading are provided, and the design resistance is determined to analyze the adhesion force between concrete and a zinc-coated steel plate. Materials and methods. Four specimens were used in testing. Each specimen represented a zinc-coated steel plate embedded in a concrete parallelepiped. A test bench, consisting of a load frame and a hydraulic cylinder, which pulled the steel plate out of a concrete parallelepiped, was used in the experiment. Results. Deformation dependences of specimens were obtained, graphs describing the dependence of displacement on loa­ding were drawn for four types of surfaces, loading values that trigger the failure of specimens and dependence between the loading value, that triggers the failure, and the structure of the embedded part of the plate, are identified. The nature of the concrete failure at the interface with a zinc-coated plate is tracked. Conclusions. The results of the experiment enable us to conclude that the joint action of concrete and a steel beam is possible without the use of additional elements in composite structures that have bent profiles. The adhesion properties of materials and the stamped part of the profile are capable of absorbing shear forces arising in structures. For a more accurate analysis of floor slabs that contain bent profiles, additional experimental studies are to be conducted. Specimens, having bent profiles embedded in concrete, will be tested in the course of these experiments.

Design and Fabrication of Rocker Bogie Mechanism

The rocker-bogie suspension mechanism its currently NASAs one of the favourite design for wheeled mobile robots, mainly because it has multipurpose capabilities to deal with different types of surface and obstacles because it uniformly distributes the overall weight over its 6 wheels at all times. That's why it has many advantages when dealing with obstacles, there is one of the disadvantage is its low average speed of operation, the rocker bogie system generally not suitable for situations where high-speed operations for which to cover large surfaces Areas. mainly due to stability problems. Our purpose is to increase the stability of the rocker-bogie mechanism system by expanding its support design structure, making it more stable and flexible while moving at high speed, at different surfaces but keeping its original flexibility against obstacles. Most of the flexibility of this method can be achieved without any mechanical modification to existing designs only a change in control strategy. Some mechanical changes are required to Achieve the maximum Advantages and to increase the rover operations speed in future. We will develop a method of driving a rocker-bogie vehicle so that it can effectively step over most obstacles rather than impacting and climbing over them. The Rocker-Bogie Mechanism system was designed to be used at slow speeds. It is capable of overcoming obstacles that are depends upon the size of a wheel.

Liquid crystal droplets under extreme confinement probed by a multiscale simulation approach

ABSTRACT In this work, we computationally investigate liquid crystal (LC) droplets in the size range 0.03–1 μm, confined within shells of combined anchoring conditions. Two different types of surface were defined to promote homeotropic and planar degenerate anchoring, respectively. We identified the LC behaviour within the nanoscale droplets using a bespoke multiscale simulation approach. To study 30 nm droplets, we used coarse grained simulations within the dissipative particle dynamics formalism; to study 0.1 μm and larger droplets, we used a finite element method based on the Landau–de Gennes theory. Good agreement between the two methods was observed in our prior analysis and was confirmed in the present work. We explicitly study droplets of size 0.1 and 1 μm by using continuum mechanics calculations. Our results for the largest droplet are consistent with those available in the literature, suggesting that the extension to smaller droplets presented here is realistic, and therefore can be helpful for innovations in which device intensification could be achieved using LC nanodroplets.

Seasonal Stability of SARS-CoV-2 in Biological Fluids.

The transmission of SARS-CoV-2 occurs by close contact with infected persons through droplets, the inhalation of infectious aerosols, and the exposure to contaminated surfaces. Previously, we determined the virus stability on different types of surfaces under indoor and seasonal climatic conditions. SARS-CoV-2 survived the longest on surfaces under winter conditions, followed by spring/fall and summer conditions, suggesting the seasonal pattern of stability on surfaces. However, under natural conditions, the virus is secreted in various biological fluids from infected humans. In this respect, it remains unclear how long the virus survives in various types of biological fluids. This study explores SARS-CoV-2 stability in virus-spiked human biological fluids under different environmental conditions by determining the virus half-life. The virus was stable for up to 21 days in nasal mucus, sputum, saliva, tear, urine, blood, and semen; it remained infectious significantly longer under winter and spring/fall conditions than under summer conditions. In contrast, the virus was only stable up to 24 h in feces and breast milk. These findings demonstrate the potential risk of infectious biological fluids in SARS-CoV-2 transmission and have implications for its seasonality.

Deep learning for observation of road surfaces and identification of path holes

Road surface irregularities not only has an impact on consistency of road, but also affects driver safety, automobile mechanical stability, and fuel consumption. To order to evaluate road roughness and spot potholes, many solutions have been suggested to remotely track the road surface quality. Some of these methods use an embedded mobile accelerometer to take a crowd sensing view to feel the surface of road. Although crowd sensing has various advantages such as ubiquity and less cost, it has some sensitivity to the problems generated by structures made by human, actions of the driver, and characteristics of the road surface which cannot be identified road anomalies. For this purpose, this paper suggests method of deep learning which helps us (a) to identify the different types of surface of road and (b) to differentiate potholes automatically from destabilizations in the crowd sensing-based application sense arising from speed bumps or driver behavior. This paper study and implement different deep learning frameworks in particular: convolutionary neural networks, LSTM networks, and computational structures for reservoirs. The tests were performed using knowledge from the real world, and the results revealed good precision in solving both of the problems.

Effect of Dust and High Temperature on Photovoltaics Performance in the New Capital Area

The trend for integrating solar Photovoltaic Panels as an alternative renewable and sustainable energy source is growing in Egypt, North Africa and the Middle East. However, these efforts are not widely accepted by the society due to their lower efficiencies. The efficiency of the photovoltaic panels is affected by many environmental parameters, which have a negative impact on system efficiency and cost of energy, dust and increased panel temperatures being the most serious. This work presents the results of a case study conducted at The British University in Egypt at El-Sherouk city to study the effect of different parameters such as dust accumulation, water cooling and coating on their performance of both mono- and poly-crystalline panels at El-Sherouk City. The effects of high temperature and dust accumulation on different solar panels placed in natural outdoor conditions at El-Sherouk City were studied and the electrical performance of dusted, cleaned, and cooled PV panels is presented. The variation in the efficiency of mono-crystalline panels installed at different tilt angles, resulting from the accumulation of dust on their surface, was also studied. The results showed that the accumulation of dust on the surface of different types of solar panels can reduce the efficiency by 30%. While the high temperature can reduce the efficiency by up to 10 %. The results showed that the power reduction percentage was 17%, 20%, 25%, 27% and 30% for tilt angles 60°,45°,30°,15° and 0°; respectively. Tilt angles 15° and 30° showed to be optimal for the installation of the PV solar system, as they resulted the highest amount of output power

Researching of the Efficiency on the Application for Complex Processing in Obtaining the Different Types of Surfaces

The influence of the effect of combining different types of processing based on the physical force acting on the surface of conductive materials and the electrochemical active action of electrolytes acting as a cutting fluid is considered. The experiments carried out and show a significant effect of these types of processing on the surface quality and the provision of the initial various physical and mechanical properties of the processed materials. The article presents various dependencies of qualitative parameters for the implementation of shaping processes using such blade processing operations as turning, threading in holes of small diameter and expanding the holes. With combined processing methods, the process of forming the finish surface is due to the combined action of the cutting tool and the anodic dissolution of the metal under the influence of an electric current in the electrolyte solution. The application of this method allows obtain higher quality parameters when machining aluminum and copper alloys, the surface formed during processing, including the preservation of such special characteristics of certain materials, such as porosity.

Environmental Stability of SARS-CoV-2 on Different Types of Surfaces under Indoor and Seasonal Climate Conditions.

Transmission of severe acute respiratory coronavirus 2 (SARS-CoV-2) mainly occurs through direct contact with an infected person via droplets. A potential role of contaminated surfaces in SARS-CoV-2 transmission has been suggested since the virus has been extensively detected on environmental surfaces. These findings have driven the investigation of virus stability on surfaces under several conditions. However, it remains unclear how long the infectious virus survives on surfaces under different climate conditions, which could play a role in predicting the seasonality of SARS-CoV-2. Therefore, the aim of this study was to estimate the virus stability and its biological half-life on various types of surfaces under indoor and seasonal climate conditions. This study revealed that SARS-CoV-2 survived the longest on surfaces under winter conditions, with a survival post-contamination on most surfaces up to 21 days, followed by spring/fall conditions, with a survival up to 7 days. Infectious virus was isolated up to 4 days post-contamination under indoor conditions, whereas no infectious virus was found at 3 days post-contamination under summer conditions. Our study demonstrates the remarkable persistence of SARS-CoV-2 on many different common surfaces, especially under winter conditions, and raises awareness to the potential risk of contaminated surfaces to spread the virus.

Current understanding of the surface contamination and contact transmission of SARS-CoV-2 in healthcare settings.

The novel coronavirus disease (COVID-19) has rapidly spread across the world and was subsequently declared as a pandemic in 2020. To overcome this public health challenge, comprehensive understanding of the disease transmission is urgently needed. Recent evidences suggest that the most common route of transmission for SARS-CoV-2 is likely via droplet, aerosol, or direct contact in a person-to-person encounter, although the possibility of transmission via fomites from surfaces cannot be ruled out entirely. Environmental contamination in COVID-19 patient rooms is widely observed due to viral shedding from both asymptomatic and symptomatic patients, and SARS-CoV-2 can survive on hospital surfaces for extended periods. Sequence of contact events can spread the virus from one surface to the other in a hospital setting. Here, we review the studies related to viral shedding by COVID-19 patients that can contaminate surfaces and survival of SARS-CoV-2 on different types of surfaces commonly found in healthcare settings, as well as evaluating the importance of surface to person transmission characteristics. Based on recent evidences from the literature, decontamination of hospital surfaces should constitute an important part of the infection control and prevention of COVID-19.

Surface critical behavior of coupled Haldane chains

The special surface transition at (2+1)-dimensional quantum critical point is precluded in corresponding classical critical point. The mechanism of such behavior which is only found in dimerized Heisenberg models so far is still under debate. To illuminate the role of symmetry protected topological (SPT) phase in inducing such nonordinary behaviors, we study a system on a two-dimensional square lattice consisted by interacting spin-1 Haldane chains, which has a genuine SPT phase--the Haldane phase--at weak interchain interactions and a quantum critical point belonging to the classical 3D O(3) universality class to the N\'eel phase. Different from models studied previously, there is no dimerization in the current model. Cutting the system along the chain direction or perpendicular to the chain direction exposes two different surfaces. Using unbiased quantum Monte Carlo simulations, we find that the two different types of surface show completely different surface critical behaviors at the bulk critical point, resulted from different surface states in the SPT phase. For the system with surfaces along the chain direction, the surface critical behavior is of ordinary type of the bulk 3D O(3) critical point, while for the surfaces perpendicular to the chain direction, the surface critical behavior is nonordinary, consistent with special transitions found in dimerized Heisenberg models. Our numerical results demonstrate that the gapless surface state in the gapped SPT phase together with the gapless mode of critical point is a pure quantum scenario that leads to the nonordinary transition.

Cubic microlattices embedded in nematic liquid crystals: a Landau-de Gennes study

We consider a Landau-de Gennes model for a connected cubic lattice scaffold in a nematic host, in a dilute regime. We analyse the homogenised limit for both cases in which the lattice of embedded particles presents or not cubic symmetry and then we compute the free effective energy of the composite material. In the cubic symmetry case, we impose different types of surface anchoring energy densities, such as quartic, Rapini-Papoular or more general versions, and, in this case, we show that we can tune any coefficient from the corresponding bulk potential, especially the phase transition temperature. In the case with loss of cubic symmetry, we prove similar results in which the effective free energy functional has now an additional term, which describes a change in the preferred alignment of the liquid crystal particles inside the domain. Moreover, we compute the rate of convergence for how fast the surface energies converge to the homogenised one and also for how fast the minimisers of the free energies tend to the minimiser of the homogenised free energy.

Fenitrothion Bio-Efficacy on Different Intradomicile Surface Types Against Anopheles (Nyssorhynchus) Albimanus in the Main Malaria Endemic Regions of Panama

Background: The use of intradomicile residual insecticide on a large scale is a proven and efficacious intervention against malaria mosquito vectors. The objective of the study was determined the bio-efficacy and resistance of fenitrothion insecticide against the mosquito An. (Nyssorhynchus.) albimanus Wiedemann . Methods: This study included seven communities located in different endemic regions where fenitrothion is used to control An. (Nys.) albimanus populations. The test of bio-efficacy and susceptibility were conducted following the WHO standard bioassay methodology. Results: The average percent mortality of An. (Nys.) albimanus exposed to fenitrothion in the seven communities tested were 96% and 92% for the first two months. This bio-efficacy was maintained until the fifth month with 81% mortality in communities with high IRS coverage. Anopheles (Nys.) albimanus was susceptible to the organophosphate insecticides fenitrothion and malathion, as well as to carbamate propoxur but resistant to pirimiphos-methyl and chlorpyrifos. Conclusion: This study demonstrates that fenitrothion maintains an elevated insecticide residuality and toxic effect on different types of surfaces until the fifth month post-application. Furthermore, An. (Nys.) albimanus remains highly susceptible to this insecticide, providing a high degree of protection against mosquito bites inside households, and interrupting malaria transmission in places with high IRS coverage and where the mosquito is still susceptible to fenitrothion application.

Determination of the Friction Coefficient in the Flat Strip Drawing Test

Current work is focused on the influence of friction in deep drawing process. Friction measurements were also conducted using a modified tribotester based on strip sliding between tools. Four different tool surfaces were tested under similar contact conditions regarding contact area, normal pressure, sliding speed, lubricant and surface characteristics to calculate the friction coefficient between the tool surface and a high strength low alloy steel sheet HSLA 380. The results showed that friction coefficient varies over a wide range with different lubricating conditions and different sliding velocities. For some sliding velocities, the coefficient of friction is stable and low, while for others it is unstable and higher. Results of the experiments reveal that this novel tribotester is a very useful tool to evaluate and compare the friction between steel sheet and tool surfaces in alloyed steel for cold working applications. The outcomes have only small dispersion within the different test series, which indicates a stable process with good repeatability. The test method enables comparison of different surface finishes and treatments, lubricants and coatings in terms of friction and galling under conditions similar to those found in sheet metal forming processes. The four different types of surfaces considered for this study were grinded, polished, nitrided and quenched/tempered. The main difference among the tested tools in this work was the surface roughness, which was found to have a strong influence on friction.

Spreading of Water Droplets on Cellulose-Based Papers: the Effect of Back-Surface Coating.

Regulation of wetting and spreading of liquid on porous material plays an important role in a variety of applications, such as waterproofing, anti-icing, antioxidation, self-cleaning, etc. In this work, we reveal the role of back-surface coating with superhydrophobic nanoparticles in controlling the spreading of water droplets on cellulose-based papers. A layer of superhydrophobic polydivinylbenzene (PDVB) nanoparticles is spin-coated on the back surface of different types of papers. The spreading of a water droplet on the top, uncoated surface is dependent on the size of the PDVB nanoparticles in the coating. Using a relationship derived from Darcy's law, we observe that the energy barrier for the spreading of water droplets on three types of papers (heavy-weight, light-weight, and slight-weight papers) decreases with the decrease of the nanoparticle size in the back-surface coating. The spreading of the water droplet is dependent on the porous structure, permeability, and compressibility of the papers. The method presented in this work provides a feasible approach to use the back-surface coating to control the wettability of papers.

Păstoritul de pe Valea Argeșului – coordonate spațiale

"Shepherding on Argeș Valley – spatial coordinates This paper presents the essential elements that define the spatial coordinate characteristic of shepherding which is practised in the sub-Carpathian villages on the Argeș Valley, following the documentary attestations of the villages, the genesis and evolution of the village boundaries, the evolution of land ownership and the right to use lands (in condominium or individually). Also within the spatial coordinate, there are researched the traditional ways in which the potential of the rural land fund is highlighted, as a result of its geomorphological, pedological, climatic qualities, etc., the study taking into consideration all the areal types with pastoral potential, not only those on the administrative territory of the villages, but also those in the mountain area destined for summer grazing. If for the presentation of origins, attestations, borderline fixation of the villages from the studied areal, documents, monographic studies and other categories of specialized works have been used, for the understanding of the manner of pastoral, individual and especially collective exploitation of the land fund by the village communities, of valorizing the fodder qualities of the different types of surfaces, it was necessary to carry out field research in the three targeted villages: Albeștii de Argeș, Corbeni and Arefu, all in the Argeș County. The visit of sheepfolds from Lespezi, Lipitoarea, Ciocanu, Podeanu, Oticu, in the alpine hollow of the Făgăraș Mountains, were necessary both for studying some elements related to the spatial coordinate (sheepfold location, daily travel routes, travel routes from the village hearth to the mountains, etc.) as well as for conducting interviews, based on an elaborate questionnaire, interviews generating unique and extremely useful information also for researching the other coordinates of the pastoral system practiced in the area. Keywords: shepherding, Argeș Valley, spatial coordinate, pastoral system, field research "

Coronavírus da Síndrome Respiratória Aguda Grave 2 (SARS-CoV-2) em Superfícies: persistência e medidas de prevenção – uma revisão sistemática

Introdução: O SARS-CoV-2 representa uma ameaça à saúde pública e medidas preventivas dependem principalmente do entendimento das rotas de transmissão do vírus, de sua estabilidade ambiental e da persistência em superfícies. Objetivo: Verificar a persistência do SARS-CoV-2 em diferentes tipos de superfícies e as medidas de prevenção contra a transmissão do vírus. Método: Foi realizada uma revisão sistemática, utilizando como referência o método PRISMA. Foram utilizadas as bases de buscas PubMed e LILACS de janeiro a junho de 2020, com os descritores: “2019-nCOV” OR “SARS-CoV-2” OR “COVID-19” AND “transmission” OR “transmission route” AND “viability” AND “surface” OR “inanimate surface" AND “prevention”. Estudos envolvendo outras doenças e/ou patógenos foram excluídos. As informações extraídas foram autor/ano, país, tipo de publicação, nome da revista, idioma, país da publicação e base de dados. Resultados: Foram identificadas 178 publicações. Foram excluídos 164 artigos, nove por idioma, 12 por outras doenças e/ou patógenos e 143 pelo título e/ou resumo. Foram incluídos 14 artigos qualitativos, sendo duas revisões sistemáticas, oito artigos de revisões narrativas, uma comunicação breve, dois artigos originais e um editorial. Treze artigos foram publicados em inglês e um em português. Conclusões: Coronavírus humanos são capazes de manter-se em diferentes superfícies por duas horas ou até nove dias. Baixas temperaturas e reduzida umidade relativa do ar favorecem a sobrevivência do SARS-CoV-2, sendo mais estável em plásticos e aço inoxidável do que em cobre e papelão. A recomendação é frequente higienização de superfícies e mãos com água, sabão ou higienizadores à base de álcool. Estudos são essenciais para melhor entender a persistência do vírus em superfícies.

Cold Spray Deposition of Copper/Tungsten Composite Coatings

This work is devoted to the study of the microstructure and the properties of the Cu-W composite coatings deposited using cold spray technology. This process allows fabrication of high-quality coatings on large surfaces of different types of materials. The technology is widely used and investigated due to technological simplicity, wide range of sprayed materials and operating temperatures. However, there are some technological problems which appear when materials with low melting temperatures are sprayed. During softening, the particles adhere to the nozzle walls and block spraying. By the way, it is possible to solve the problem adding some ceramics particles to the spraying mixture of powders. As a result, the formed coating will have better mechanical properties and the technological problem will be solved. The analysis of the general results of the microstructure studies and experiments, and comparison with other coating methods are given. Moreover, the experimental procedure of samples preparation and used equipment are given. It is shown the microstructure before and after heat treatment of the samples sprayed, microhardness measurements, thermal conductivity measurements.

Fabrication and friction characteristics of arbitrary biosurfaces.

There are many different types of surfaces found in nature which can increase or reduce friction, such as the well-studied frog toe or lotus leaf. However, methods for replicating these surfaces on a large scale for use in industrial applications are needed in order to take advantage of this natural friction engineering. Most replication processes rely on molding that requires an input surface size comparable to the desired output surface. We present a novel approach of replicating large-scale biosurfaces using a laser scanning confocal microscope for surface digitization and 3D two-photon lithography for the fabrication of the digitized surface. Two different natural surfaces (banana skin and daffodil petal) were replicated. An intermediary tiling process was used to cover a target area of arbitrary size independent of the input texture size. The surfaces were coated with a thin layer of ZnO, and the frictional and wettability characteristics of the replicated surfaces were then examined, demonstrating significant friction reduction up to 42% and increased hydrophobicity due to the presence of texture.