Which Of The Following Is A Consequence Of A Macroscale Climate Control?

Label of Nanomaterials for Energy Storage

A.One thousand. Bittner , Five. Koroteev , in Emerging Nanotechnologies in Rechargeable Energy Storage Systems, 2017

i Macro- and Microscale Characterization

Macroscale analyses are standard physicochemical methods, and do not differ in neither application nor data evaluation when nanomaterials are used. Examples [v,6] comprise elemental assay (combustion), mass spectroscopy, gravimetry, assay of the water content (Karl Fischer titration); furthermore, calorimetry [7], and electrical/electrochemical characterization (impedance, voltammetry) [8] are very typical. The sample preparation is a cardinal issue to obtain suitable information; it is ideally put in the context of in situ and ex situ characterization (Section 2). The microscale can exist of corking relevance, and in fact complicates many methods significantly, for instance, past undesired light handful for photon methods, by focus and contrast problems in electron-based methods; scanning probe methods can normally not even be applied on microrough surfaces. Still, most techniques let selecting microscale areas, and thus a comparing betwixt diverse parts of a sample (Fig. 5.ii). The results should ever be checked for their compatibility with the average values, measured on the macroscale. In other words, a single microscale area is not e'er representative for the complete sample. The micromethods require either new equipment, or add-ons to an existing nonimaging or macroscale imaging tool. Examples are:

Figure 5.2. Various methods, which are ordinarily practical on the macroscale, that is, without spatial resolution, that can be modified to provide information of milli- and micrometer-sized sample parts.

•

UV–vis and Raman spectroscopy [i,two,9] combined with an optical microscope;

•

IR microscopy combined with a FTIR spectrometer [2];

•

Focus methods for X-rays, usually installed at synchrotron sources, and combined with XAS (including EXAFS) and XRD;

•

XPS with microimaging, where the obtained spectral information correspond to standard macroscale data.

Especially for the 10-ray techniques, the awarding of microimaging can exist circuitous. Even so, the microscopy options are very impressive, and allow imaging details and defects [ten–12]; scaling down to the nanoscale is well underway, so these methods will exist discussed in detail in the department on nanomethods (Section 5).

For a complete give-and-take of scales, one should not forget the diminutive (or molecular scale). Simply a very few methods allow researchers to address information technology directly (TEM or AFM at high resolution), but many methods provide structural data of utmost precision (XRD), or spectroscopic identification of chemic groups (IR) [ii]. These methods will be discussed aslope the related nanoscale methods, without specific reference to the diminutive scale, simply mainly under the heading of chemical analysis (Section iv).

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Macromodeling

E. Minga , ... I. Calio' , in Numerical Modeling of Masonry and Historical Structures, 2019

8.half dozen Conclusions

Macroscale modeling represents an effective strategy to describe the response of masonry components and structures nether different loading conditions including extreme loading like an earthquake. This chapter surveyed some of the chief modeling approaches at the macroscale. They include continuum FE descriptions, where URM is causeless equally a homogeneous material and specific constitutive laws are employed to correspond material nonlinearity; and efficient 1D equivalent frame models and discrete 2nd or 3D macromodels, where rigid or deformable blocks interact along their boundaries through nonlinear springs to correspond large portions of masonry components. Moreover, a novel 3D masonry macroelement formulation, which can represent the main in-airplane and out-of-plane collapse mechanisms of URM panels, was presented. It is characterized by significant enhancements on the kinematic and material descriptions compared to previous macroscale macromodels. According to the proposed macroscale clarification, flexural cracking, shear sliding, and toe crushing are represented through damage concentrated along the element boundaries. The in-plane shear cracking and out-of-airplane diagonal bully modes are described in a phenomenological way past nonlinear springs associated with the respective deformation modes of the inner block. The constitutive beliefs of the springs is coupled with the mean normal stress in the boundary interfaces, which provides the level of solitude. The enhanced kinematics, every bit well as the detailed cohesive-frictional constitutive police along the boundaries, allow the accurate representation of the in-plane and out-of-aeroplane nonlinear beliefs of URM components and the reliable prediction of failure modes with a reduced number of elements. This was shown in numerical examples, including comparisons against the results of physical tests on masonry walls nether in-plane and out-of-plane cyclic loading.

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An overview of continuum harm models used to simulate intralaminar failure mechanisms in advanced composite materials

A. Forghani , ... R. Vaziri , in Numerical Modelling of Failure in Advanced Blended Materials, 2015

6.4.three Macroscale models

Macroscale models are the only models that can be used practically for simulation of large-calibration structures. These models are designed to simulate the overall response of the laminate. The macroscale models are typically not capable of predicting the details of the damage events in the layers. Numerical efficiency and likewise accurately predicting the behaviour of the structure in terms of macroscale parameters are the main objectives of the macroscale models.

As nosotros have discussed, the ply-based arroyo encounters two problems: loftier computational toll and the assumption of the independent behaviour of layers. The sublaminate-based approach, which was first introduced by Williams et al. (2003), takes the sublaminate as the building block of the laminated composite structure. This approach considers the sublaminates as the representative volume and every bit the base level for constructing the impairment model. Given that the response of a single lamina in a stack is governed by its in situ characteristics, only a model constructed at the calibration of a cake of layers or sublaminate has the potential to incorporate the interactions of damage mechanisms between layers caused past the stacking sequence.

The goal of the sublaminate approach is to predict, in a smeared manner, the essence of the overall nonlinear response of a laminated composite structure (e.g., its stiffness, load-carrying capacity, stability and post-tiptop behaviour) due to progressive damage caused past a given loading condition rather than capturing the details of the damage in each and every layer of the laminate. In this arroyo, in contrast with the ply-based approach, an element in the numerical simulation represents a sublaminate.

As the damage behaviour of the sublaminate depends on orientation, sequence and thickness of its constituent layers, each variant of the stacking sequence must be regarded every bit a distinct material for which the material model assigned to the sublaminate needs to be recalibrated.

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Applications—Multiphysics Systems

Zhuming Bi , in Finite Element Analysis Applications, 2018

11.6.4.i.3 Shapes

At the macroscale of contact, the conformance of 2 contact surfaces affects stress distribution. The contacts tin can be generally classified into point contact, line contact, and area contact. The macroscale features not only determine the stress distribution for solid contact, just also affect purlieus constraints of the fluid flow significantly. To ascertain an EHL model, information technology poses a great claiming in specifying appropriate boundary conditions due to open up inlets or outlets of the fluid flow surrounding the contact points, lines, or areas. Surface textures over a surface, such as dimples and bumps, tin can be treated every bit macroscale features in static analysis or flow simulation.

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Carbon Nanotubes for Electrochemical Capacitors

Y. Zhang , ... Westward. Yuan , in Industrial Applications of Carbon Nanotubes, 2017

x.two.ane CNT Compages Variety for Electrodes

CNTs are 1D hollow tubular graphite with ultrahigh length-diameter ratio. CNTs including SWCNTs, DWCNTs, and MWCNTs tin can be prepared through various methods such as chemical vapor decomposition (CVD), laser ablation, arc discharge, etc. (23) . Like other carbon materials, electric charges are stored electrostatically in the electrical double layers on the huge surface of individual CNTs. All the same, by simply mixing pure CNTs with carbon black and polymer binders to class an electrode, typically low SC (varied from xx to eighty   F/g) every bit well as energy density (∼seven   Wh/kg) and power densities (∼xx   kW/kg) of the as-prepared ECs are exhibited (24–26) . To make full apply of the many claim of individual CNTs at a macroscopic level in free energy storage devices including ECs, it is desirable to assemble CNTs into various macroscopic CNT-based materials with huge SSA and proper PSD (6,27) . Too, the effective SSA and electrochemical performance of CNT-based electrodes are closely related to their architecture, which largely determines the transportation paths of both ions and electrons.

Macroscale CNT assemblies tin can be strategically divided into two groups, unaligned and aligned. The unaligned CNT assemblies ways that most CNTs are arranged or grown randomly on the base; agglomeration of large amounts of CNTs, which are detrimental for constructive SSA and ion transportation, tin can be observed anywhere in the unaligned CNT films and networks (28,29) . The aligned CNT assemblies with highly organized alignments include 1D-CNT fibers/yarns, 2nd-CNT films/papers, and 3D-CNT arrays/solids; they are normally produced based on initially elaborate epitome designing. Thus far, enough of work has been carried out to fabricate regular macroscopic CNT assemblies. Compared with the unaligned ones, aligned CNT assemblies are more hands handled and applied under various conditions in addition to larger values of both SC and capacitance retention because of the post-obit advantages (28,30,31) :

i.

Aligned designs can provide proper PSD and ordered arrays with highly organized transportation paths.

2.

Advisable altitude between CNTs, fibers, films, and arrays can be adjusted in the aligned architecture.

3.

Aligned architecture is considered to have straight and firm electrical contact with electric current collectors, similar to a metal plate or foamed network.

Continuous and ordered CNT fibers with diameters ranging from micrometers to millimeters are 1D-CNT assemblies. During the past several years, there have been numerous reports in the literature of the fabrication of dandy CNT fibers through a wide range of technologies (32) . Typically, CNT fibers tin can be prepared through two kinds of spinning methods: solution-land spinning and solid-state spinning, which consists of spinning from a vertically aligned CNT assortment, spinning from CNT aerogel, and twisting/rolling from a CNT film (33–35) . Similar to carbon fibers, the CNT fibers are too flexible, integratable, wear, and lightweight. Supercapacitors based on CNT fibers can be easily fabricated through straight twisting two fiber electrodes or wrapping two electrodes on cobweb substrate to form a coaxial structure in the air under balmy conditions; they can be also more stably operated with a long lifetime during application (35) . E'er since a 30   cm-long CNT fiber was fabricated in 2002, plenty of research has been focused on the electrochemical performance of CNT fiber-based ECs.

As another macroscale CNT assembly, 2nd-CNT films with thicknesses ranging from tens of nanometers to micrometers can exist prepared through direct growth using the CVD method, pulling out a CNT bundle with tweezers from CNT arrays, posttreating CNT suspensions, and dry drawing from CNT arrays (36,37) . CNT films not only possess all the claim of CNTs, their interconnected structure makes them a suitable self-standing electrode material with amend electrical conductivity for supercapacitors. Besides, CNT films are highly stretchable and offer a loftier fault tolerance because they possess many electric current pathways; CNT films can still transport electric charges even when certain links are disconnected. As well, highly stretchable CNT films could offer a loftier fault tolerance because of the existing abundant current pathways. CNT films tin can even so send electrical charges even when some links are destroyed during stretching (11,38) .

The 3rd kind of macroscale CNT assembly is 3D-CNT arrays/solids, which refer to aligned CNTs vertically grown on certain plane substrates with heights up to the millimeter scale. Typically, aligned CNT arrays tin can be prepared by the CVD method on nonconductive substrates such as silicon wafers and silicon dioxide films, which were previously deposited with catalysts; the grown CNT arrays could be further transferred to another substrate according to their final application (39,xl) . For application in ECs as free-standing electrodes, CNT arrays are often transferred to conductive substrates such every bit metal foils, which could simultaneously serve as electric current collectors. In fact, considering of their high electrical conductivity, ordered porous structures with multiple paths for diffusion of ions and electrons, fantabulous mechanical properties, highly effective SSA, and tunable PSD, aligned CNT arrays are very promising for electrode materials of ECs (five,41,42) . Arable enquiry has been carried out to explore the electrochemical potential of CNT arrays ever since they were showtime reported in 1996 (39,43–46) .

In addition to maintaining the unique intrinsic properties of private CNTs, regular macroscale CNT assemblies take been endowed with a number of new properties that are very highly-seasoned in novel ECs. For instance, highly flexible and stretchable 1D-CNT fibers with loftier electrical electrical conductivity and tensile force are very promising materials for wearable ECs. As a basic building block, CNT fibers tin can be fabricated into fabrics and any other designed preforms through a simple knitting procedure. Similar to 1D-CNT fibers, the 2d-CNT films also possess first-class mechanical flexibility and stretchability. Moreover, CNT films with optical transparency could exist developed into stretchable thin motion-picture show-based transparent electronics. With the assistance of the zipping effect of liquids, the 3D-CNT arrays can be fatigued into superaligned CNT arrays of different shapes with higher density and more regular structure, while the intrinsic backdrop of pristine CNT arrays such every bit high SSA and loftier electrical conductivity could exist maintained (47) . With decreased average tube separation (∼0.9   nm), which is still big enough for the access of electrolyte ions, a higher volumetric capacitance of the CNT array-based electrode is thus expected (47,48) .

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24th European Symposium on Calculator Aided Process Technology

Ágnes Bárkányi , ... Béla 1000. Lakatos , in Estimator Aided Chemic Technology, 2014

two Model evolution

The model developed contains micro-, meso- and macro-calibration processes inside the polymerization reactor, forming a complex three-calibration system.

Micro-scale: Polymer reactions, related with the kinetic mechanism and micromixing occur at the micro-calibration.

Meso-scale: At meso-scale occur the collision induced coalescence and break upwardly of droplets.

Macro-scale: At this scale, the overall mass and energy balances, the heat and mass transfer from the reactor too equally the reactor dynamics and control tin exist described.

In order to take the interdependence of micro- and meso-calibration processes into consideration, suspension polymerization of vinyl chloride is modeled by using the population balance approach. If the reactor is well mixed at macro-scale, the population of droplets can be described by the population density role n(.,.,.t) past means of which northward{u,c,T,t)dvdcdT provides the number of droplets from the droplets book and temperature intervals (five,v + du) and (T,T + dT), and from the region (c, c + dc) of concentrations in a unit volume of break at fourth dimension t. Under such weather the behavior of droplets population in a batch reactor is governed by the population balance equation (Lakatos, 2011)

(1) $\begin{array}{l}\frac{\partial n\left(v,c,T,t\right)}{\partial t}+\frac{\partial }{\partial c}\left[\frac{dc}{dt}n\left(v,c,T,t\right)\right]+\frac{\partial }{\partial T}\left[\frac{dT}{dt}\mathrm{northward}\left(v,c,T,t\right)\right]=\hfill \\ \begin{array}{l}{\text{Yard}}_b\left[n\left(v,c,T,t\right)\right]+{\text{Chiliad}}_a\left[n\left(v,c,T,t\right)\right]\hfill \end{array}+{\text{M}}_{c/r}\left[n\left(v,c,T,t\right)\right]\hfill \end{array}$

where the second and third terms on the left paw side provide the rates of continuous changes of the population density role due to the mass and heat effects of chemic reactions while the terms on the right hand side of Eq.(ane) provide, in turn, the rates of bound-like changes of population density office because of coalescence, pause up and standoff induced estrus exchange between the colliding droplets (Lakatos, 2011).

In intermission polymerization, mass transfer between the dispersed and continuous phases is negligible, therefore the detailed model of the reactor consists of Eq.(1) completed with the macro-scale heat residual equations for the dispersed and continuous phases and the cooling medium making possible to analyze the effects of temperature changes of the continuous phase on polymer properties.

The oestrus balance for a droplet is

(two) ${\rho }_d{c}_{p,d}{\mathrm{five}}_d\frac{d{T}_d}{dt}=v_d\left(-\Delta {\text{H}}_r\right)\cdot {\text{R}}_r\left(c_d,T_d\right)-a_d{h}_{dc}\left(T_d-T_c\right)$

where T _d, ρ_d, v_d and c_p,d are the temperature, density, volume and heat chapters of a droplet, T_c is the temperature of the continuous phase, a_d is the surface of a droplet, h_dc is the heat transfer coefficient between a droplet and the continuous phase, R_r and -AH_r are the vectors of the reaction rates and reaction heats, and c_d is the vector of concentrations of species in a droplet. The convective estrus transfer coefficient (h_dc) is calculated by empirical expressions.

The heat balance for the continuous phase takes the form

(iii) ${\rho }_c{c}_{p,c}\epsilon \mathrm{Five}\frac{dT}{dt}=V{\displaystyle \underset{T_{\text{min}}}{\overset{T_{\text{max}}}{\int }}{\displaystyle \underset{0}{\overset{{\text{c}}_{\text{thou}}}{\int }}{\displaystyle \underset{0}{\overset{5_m}{\int }}{a}_d{h}_{dc}\left(T-T_c\right)n\left(v,c,T,t\right)dvdcdT-A_{cj}{h}_{cj}V\left(T_c-T_j\right)}}}$

where T_c, p_c, ε and c_p,c are the temperature, density, volumetric ratio and estrus capacity of the continuous phase, 5 is the volume of the suspension, h_cj and A_cj denote the coefficient and the effective surface of oestrus transfer betwixt the continuous phase and the cooling medium. In Eq.(3), T_j denotes the temperature of the cooling medium in the jacket assumed to be a pace-wise process at the initial moment of time.The rut residue for the cooling medium is

(4) $V_j{c}_{p,j}{\rho }_j\frac{dT}{dt}=c_{p,j}{F}_j\left(T_{j,\mathrm{thousand}}-T_j\right)-A_{cj}{h}_{cj}V\left(T_c-T_j\right)$

where F_j, c_p,_c and T_J,in denote the mass flow rate, the heat capacity and the inlet temperature of the cooling medium.

The mixed set of the integral-differential Eq.(1) with the ordinary differential Eqs.(two)–(3) of macro-scale heat balances was solved by developing a Monte Carlo procedure (Bárkányi et al., 2013a) combining the deterministic processes of chemic reactions within the droplets and the heat transfer in the continuous stage with the effects of random collisions of droplets. This procedure provides, in principle, a Monte Carlo method of solution of the multivariable population balance equation.

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Dark-green Belittling Chemistry

Thousand. de la Guardia , S. Armenta , in Comprehensive Analytical Chemistry, 2011

seven.5 Spectroscopic Detection

Macro-scale optical detection, especially spectrometric detection, is usually employed due to its wide range of applications. To focus micron-sized detection areas using macro-scale spectrometric systems with pinholes or optical fibers is commonly called the "off-flake approach". This approach provides very low levels of groundwork signal which, combined with very sensitive photon detection techniques, results in very low limits of detection. However, the reduction of the optical pathlength decreases the sensitivity of the method, in particular for absorbance measurements. Currently, there are a wide range of intense light-emitting diodes available and photodiodes that can exist coupled directly to microfluidic devices to provide a miniaturized technique of on-flake detection. The existing devices in the "off-scrap approach" are generally well adult either as bootleg detection systems or commercial instruments, such equally Shimadzu MCE-2010, Hitachi SV1100, and Agilent Bioanalyzer 21000.

UV/vis absorbance detection is the most widely used detection method in macro sensing devices. However, the small-scale dimensions of a microchip channel are a severe limitation for a sensitive and reliable absorbance measurement. This is the reason for the few examples of absorbance-based detection systems in microfluidic devices [97].

Equally mentioned earlier, fluorescence detection is today even so the most widely used optical method for microsensing systems, due to its superior selectivity and sensitivity [98]. Although a variety of excitation sources are available, laser-induced fluorescence is most hands adapted to the dimensions of microchips.

Chemiluminescence as a detection method for microsensing systems has the advantages of a high sensitivity, low detection limits, and uncomplicated instrumentation equally compared with other spectrophotometric techniques, due to the exclusion of an external low-cal source [99]. All the same, the main drawback of this technique is that chemiluminescence reagent needs to be mixed with the separated analytes earlier detection and thus a rather complex microchip setup is required.

On the other hand, the integration of optical components or functions in a microfluidic platform that should be able to perform all chemical functions and detection in a single device, requires increased integration of fluidic elements, with electrical and other types of elements, thus providing an "on-flake approach".

Direct electronic optical sensors like the silicon photodiode operate by converting captivated photons directly into electronic carriers which are ultimately detected. Alternatively, many semiconductors and combinations of them form the basis of laser diodes and lite-emitting diodes, a class of devices producing low-cal in different wavelength regions from the blueish to the nearly infrared. From both a materials and technology standpoint, the integration of optical functions inside a microchip is very promising. However, the existing devices in the "on-chip approach" are generally even so in their infancy [100].

The integration of microlenses and planar waveguides in microfluidic devices is useful for the comeback of detection in sensing systems. For instance, by using a planar waveguide the optical pathlength can be increased for absorbance measurements, or past focusing the light into the aqueduct in lodge to increase the excitation power for fluorescence measurements.

Applications of on-chip absorbance measurements using a commercially available complementary metal oxide semiconductor imager chip, bonded together with a microfluidic aqueduct network bandage in polydimethyl siloxane, tin can be found in the literature [101].

Moreover, microlenses accept been fabricated straight into a glass fleck for the collection of fluorescence lite past melting islands of photoresist into a hemispherical shape [102]. In order to have a meaty system, a pinhole, an interference filter, and a photodetector were placed in close proximity to the microlens.

Organic low-cal-emitting diodes (OLEDs) have been successfully integrated as a lightweight flat panel light source. Their main reward compared to LEDs is their flat moving picture-similar shape. It makes it easier to contain them into microfluidic devices and to bring them into close proximity of the aqueduct. All the same, their broad emission spectra require additional excitation filters. OLEDs placed on the rear side of a glass substrate and a channel cast in polydimethylsiloxane (PDMS) on the front side showed the emission peak centered at 520   nm and had a relatively wide peak of 70   nm [103].

Photodiodes have been made in the aforementioned microchip at the bottom of the microfluidic channels via a monolithic approach [104] as an integrated detector to perform chemiluminescence. In order to lower the detection limit, the photodetector sensitivity was improved by fabricating diodes with a shallow junction to reduce the recombination of photocarriers and thereby to increase the quantum efficiency.

The incorporation of solid particles into microfluidic devices for SPEs and immunoassays, by fabricating a retaining feature in the microchannel which confines the particles in a specific location inside the microfluidic network [105,106], or by trapping and manipulating chaplet inside fluid streams using special channel geometries incorporating planar diverging and converging channel elements [107] has been also employed. Solid particles are used equally sensing particles points and thus contribute to the development of new and more sensitive sensing microfluidic systems. The aforementioned strategy tin can be considered a miniaturization of the solid phase spectroscopy (SPS), proposed in 1976 past G. Yoshimura [108] and consists of a combination of an active solid back up to preconcentrate the analyte and the straight measurement of the light assimilation of the analyte sorbed on the solid phase. The main advantages of this technique are those related to increased sensitivity and selectivity, improved sample throughput, article, automation and reduction of reagents, and solid supports consumption [109].

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Tribological Properties of Interfacial Molecular Films

A. Jabbarzadeh , in Encyclopedia of Interfacial Chemistry, 2018

A Brief History

For macroscale applications, the Stribeck ¹ curve is oftentimes used to describe the key relationship betwixt friction and the operational conditions (speed, viscosity, and load). The Stribeck curve for a fluid lubricated periodical begetting in Fig. 1 shows the typical human relationship betwixt the friction coefficient and operational weather quantified past the begetting number (ωη/L). For such macroscale mechanical contacts, depending on the speed, viscosity, and load, the two contacting surfaces showroom a range of friction coefficients which largely rely on the nature of the fluid film that separates them. Four lubrication regimes are possible here:

Fig. i. The Stribeck bend for a lubricated journal bearing.

•

Hydrodynamic (HD): Lubrication by a thick fluid film.

•

Elastohydrodynamic (EHD): Lubrication past a thin fluid film accompanied by local surface deformation for geometrically nonconforming contacts.

•

A mixed lubrication regime with a combined dry and lubricated contact.

•

A boundary lubrication regime where just a molecularly thin motion picture separates the surfaces.

The lubrication activity in the EHD and Hard disk drive lubrication regimes is determined largely past the rheological properties of the lubricant and primarily by its viscosity which depends on temperature, pressure, molecular structure, and shear rate (nonNewtonian lubricants). EHD and HD lubrication regimes occur at higher relative speeds, lower loads, and typically a continuous fluid motion-picture show of appreciable thickness forms that separates the surfaces and the load is supported by the pressure generated inside this fluid film. The boundary lubrication regime occurs at the outset-upwards, lower speeds, and college loads; however, the lubricant film thickness that forms may be comparable to the size of molecules. Therefore, the static friction coefficient between ii moving surfaces is affected by the boundary lubrication.

Minimizing static friction is especially important in the low energy showtime-upward for various machinery with moving parts. It is also important for MEMS which may exist operating merely under a purlieus lubrication regime where loftier static friction may result in stiction of the parts and failure of the device. The boundary lubrication movie that forms in this state of affairs largely depends on the chemical-physical properties of the principal base lubricant and the surface. A molecularly thin lubricant layer and additives that react with the surface form the last protective boundary layer to prevent straight contact between the surfaces. The abovementioned simple motion-picture show constitutes the ground of tribological activeness of macroscale systems.

The need for efficient boundary lubrication in macroscale applications provides a necessary rationale for agreement the tribological properties of molecularly sparse layers of lubricants. On the other hand, the advocacy in nanotechnology and miniaturization techniques has led to the emergence of new devices and applications where macroscale approaches are inadequate to achieve efficient tribological systems. For these systems, bulk fluid lubrication is not feasible due to negligible inertia furnishings and the increased role of adhesion and solitude-induced phenomena. Three modes of lubrication are specifically relevant to interfacial molecular films which form the concluding line of defence against wear in tribological applications: molecularly sparse unbounded lubrication films; chemisorbed/physisorbed monolayers such every bit Langmuir-Blodgett and cocky-assembled monolayers; and lubrication past polymer brushes and aqueous lubrication. Here we shall discuss what we know nigh the tribological phenomena for these films and some of the interesting observations made in this field via computational and experimental means.

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Phenolic resins as a matrix material in avant-garde fiber-reinforced polymer (FRP) composites

E. Frollini , ... E.C. Ramires , in Advanced Fibre-Reinforced Polymer (FRP) Composites for Structural Applications, 2013

ii.6.one Macroscale reinforcements

Macroscale reinforcements and composites have thus far received the near investigation and application. The remarkable advances in the evolution of these polymeric matrices composites in the twentieth century have fabricated these materials prominent, which is expected to keep despite advances in smaller-scale, mainly nanometric, reinforcements.

Glass fibers are widely used to reinforce phenolic composites, can exist produced as continuous strands or filaments with different diameters, and are bachelor in dissimilar compositions such as E-, C- and S-glass, which are characterized past dissimilar specific properties (Frollini and Castellan, 2012). Compared to other drinking glass composites, phenolic-glass composites accept depression flammability and skilful fire resistance, produce much less smoke, and less carbon monoxide when they are thermally degraded. These characteristics have led phenolic-drinking glass fibers to become the composites of option for employ in the cabin interiors of wide-bodied passenger aircraft, besides equally in ceiling panels, structural floor and overhead stowage bins (Mouritz, 2006).

Glass fibers with tailored backdrop accept been developed to meet specific applications, with some designed to be compatible with military specifications for ballistic performance (Taylor, 2010).

Phenolic composites can positively impact the edifice and construction industry by improving condom and reducing cost. Phenolic/glass laminates are important alternatives for construction applications due to properties such as the availability of several processing techniques, assuasive a pregnant degree of pattern liberty; the inherent fire resistance of the fabric, eliminating the demand for mineral additives and thus reducing the full weight; and the reduced risk of the spread of burn due to fire-resistant properties and the lower thermal electrical conductivity of phenolic-glass compared to metals (Forsdyke, 2002).

Carbon fibers (CF) tin can be produced in unlike forms, for instance as mats, continuous filament tows, and chopped fibers. CF tin can exist prepared from organic precursors (cellulose, pitch, polyacrylonitrile (Pan), some phenolic fibers) past controlling their pyrolysis. The backdrop of CF such equally low weight, high strength and high modulus, fatigue resistance and vibration damping, corrosion resistance, good friction and wear qualities, low thermal expansion, and thermal and electrical electrical conductivity are highly attractive for the aerospace industry; in fact, the requirements of this sector played a major function in stimulating the evolution of these fibers (Choi et al., 2000; Frollini and Castellan, 2012). All the same, the unique properties of these fibers have led to their applications in other segments, and since the 1970s and 1980s CF take been used in sporting and leisure goods such as fishing rods, golf society shafts and lawn tennis rackets (Ogawa, 2000).

Concerns that have emerged from the final decades of the twentieth century relating to safety and environmental issues take led to further expansion of the applications of CF, including the product of natural gas tanks for vehicles due to their low carbon dioxide emissions and make clean exhaust gas, and blades for wind-power generators (Ogawa, 2000).

Safety concerns accept led to the utilize of CF-reinforced plastics (CFRP) and CF-reinforced physical (CFR-concrete) equally earthquake-resistant materials. In this area of application, CF-reinforced wood (CFRWood) may be useful in architecture because of its effectiveness in reducing carbon dioxide emissions and promoting environmental conservation. Investigations on CFRWood and PAN-based CF occurred about simultaneously. I case is the development of CF-reinforced glued laminated timber (CFR-glulam) composed of wood, a phenolic-type resin and a CF composite canvas. Bated from skillful wettability for CF, the phenolic-type resin developed for this application exhibited reactivity towards the functional groups nowadays at the CF surface. In improver, every bit both the CF-phenolic composite sheet and wood are rich in OH groups, the adhesion between the 2 is favored, and conventional resins tin can be used to glue them together. This blazon of material can be used as a board reinforcement material and for repairing firm and bridge components (Ogawa, 2000).

Structural profiles based on FRP composites are produced for utilise in the construction industry for building and span superstructure applications (Bakis et al., 2002). Pultrusion process is the manufacturing method of choice for this awarding due to production consistency and economic considerations. Pultrusion produces continuous sections of unidirectionally reinforced composites and supplies thick-walled structural components for marine, civil applied science and high-rise construction applications (Gardziella et al., 2000). Phenolics are used every bit thermosetting resins in the pultrusion process, along with polyesters and epoxy materials. CF fiber bundles (tows), glass fiber bundles (rovings), continuous strand mats, and nonwoven surfacing veils are used equally reinforcements (Bakis et al., 2002).

Phenolic composites reinforced with CF are likewise used for load-bearing materials. Phenolics have skilful resistance to seizure and work well with steel or bronze journals when lubricants such as oil or water are used. In these applications, the depression thermal conductivity of phenolics is overcome by the presence of CF because the phenolic thermoset usually has a thermal conductivity of approximately 0.35 Due west/thousand K, i.e., approximately one/150 that of steel, which may pb to bearing failure by charring (Kim et al., 2009).

Aramid fibers are highly oriented fibers derived from effluvious polyamides, with Kevlar and Nomex as 2 prominent examples. The woven cloth of aramids combined with phenolic resins produces high-performance composites for ballistic applications, where the projectile energy is mainly absorbed by the cobweb with a high strength and modulus (Gardziella et al., 2000).

Fiber-reinforced composites take high stiffness-to-weight ratios, but this ratio may be increased if, instead of a monolithic construction, two thin composite facesheets of the aforementioned weight (for example, plastics reinforced with phenolic drinking glass or carbon fibers), separated past a cellular core, are used. A phenolic resin-impregnated aramid newspaper honeycomb (Nomex honeycomb) is commonly used in the cadre construction. These structures are advisable for applications in which weight reduction and fire safety are disquisitional, such as in ground and air transportation.

Thermosetting phenolic resins are used in combination with other components equally friction materials for restriction systems. The design of such systems should account for the need to maintain a stable and reliable friction forcefulness under a diverseness of conditions, such as wide ranges of pedal pressure, vehicle speed, temperature and humidity. Fibers represent to one of the ingredients and are used as reinforcement. Aramid lurid performs well as a reinforcement fiber in such systems because of its good filler retention, leading to enhanced wear resistance and friction stability (Kim and Jang, 2000).

The search for alternatives to raw materials derived from fossil fuels has accelerated in contempo decades and has reached the area of polymer matrix composites. In the case of phenolic matrices, several alternatives have been considered, particularly for the phenolic component.

Regarding reinforcements, involvement has re-emerged in recent decades effectually cellulosic and lignocellulosic fibers, which were used in early phenolic applications. Phenolic resins are used as adhesives for binding forest in different composites, such as panels, molded products and technology lumber materials (Gardziella et al., 2000). Phenolics are likewise stabilized binders for cotton or other cellulosic fibers for the production of interior automotive parts besides equally insulating or damping materials (Schuh and Gayer, 1997).

Fibers such as sisal (Megiatto Jr. et al., 2009; Ramires et al., 2010a, 2010b), sugarcane bagasse (Hoareau et al., 2006; Trindade et al., 2004), coconut (Barbosa et al., 2010) and curaua (Trindade et al., 2005) have been used equally reinforcements of phenolic-type matrices.

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Microscale and Macroscale Modeling of Microalgae Tillage in Photobioreactor: A Review and Perspective

Choon Gek Khoo , ... Keat Teong Lee , in Advances in Feedstock Conversion Technologies for Alternative Fuels and Bioproducts, 2019

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Past considering macro- and microscale factors when amalgam a mathematical model tin ameliorate the agreement of complex microalgae growth in a PBR. Besides, mathematical descriptions on reaction-diffusion provide a clear insight on the scale-up process. Most of the bachelor mathematical models predict the dynamic state of microalgae growth and their transport miracle separately by using numerical methods with sure modification. However, more theoretical frameworks on the integration of both macro- and microscale modeling associated with experimental validation are required to enhance the operation of PBRs at commercial scale and to improve the economic feasibility of microalgae biofuel production.

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Which Of The Following Is A Consequence Of A Macroscale Climate Control?,

Source: https://www.sciencedirect.com/topics/engineering/macroscale

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