Academic literature on the topic 'Average cubic'
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Journal articles on the topic "Average cubic"
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Das, V. B., and A. Kumar. "Deficient cubic splines with average slope matching." Analysis in Theory and Applications 21, no. 1 (2005): 1–14. http://dx.doi.org/10.1007/bf02835245.
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Donoso, Sebastián, and Wenbo Sun. "A pointwise cubic average for two commuting transformations." Israel Journal of Mathematics 216, no. 2 (2016): 657–78. http://dx.doi.org/10.1007/s11856-016-1423-5.
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Peng, D. Y., X. H. Niu, and X. H. Tang. "Average Hamming correlation for the cubic polynomial hopping sequences." IET Communications 4, no. 15 (2010): 1775. http://dx.doi.org/10.1049/iet-com.2009.0783.
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Mauk, Clay, and Saul Stahl. "Cubic graphs whose average number of regions is small." Discrete Mathematics 159, no. 1-3 (1996): 285–90. http://dx.doi.org/10.1016/0012-365x(95)00089-f.
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Liu Gaoyou, 刘高佑, 安. 宁. An Ning, 韩兴伟 Han Xingwei, et al. "Study on average reflex optical path length of cubic cavity." Infrared and Laser Engineering 45, no. 11 (2016): 1118003. http://dx.doi.org/10.3788/irla201645.1118003.
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Liu Gaoyou, 刘高佑, 安. 宁. An Ning, 韩兴伟 Han Xingwei, et al. "Study on average reflex optical path length of cubic cavity." Infrared and Laser Engineering 45, no. 11 (2016): 1118003. http://dx.doi.org/10.3788/irla20164511.1118003.
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Baier, Stephan, and Ulrich Derenthal. "Quadratic congruences on average and rational points on cubic surfaces." Acta Arithmetica 171, no. 2 (2015): 145–71. http://dx.doi.org/10.4064/aa171-2-3.
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Jung, Hwanyup. "NOTE ON AVERAGE OF CLASS NUMBERS OF CUBIC FUNCTION FIELDS." Korean Journal of Mathematics 22, no. 3 (2014): 419–27. http://dx.doi.org/10.11568/kjm.2014.22.3.419.
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Shi, Lilian, and Yue Yuan. "Hybrid Weighted Arithmetic and Geometric Aggregation Operator of Neutrosophic Cubic Sets for MADM." Symmetry 11, no. 2 (2019): 278. http://dx.doi.org/10.3390/sym11020278.
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Neutrosophic cubic sets (NCSs) can express complex multi-attribute decision-making (MADM) problems with its interval and single-valued neutrosophic numbers simultaneously. The weighted arithmetic average (WAA) and geometric average (WGA) operators are common aggregation operators for handling MADM problems. However, the neutrosophic cubic weighted arithmetic average (NCWAA) and neutrosophic cubic geometric weighted average (NCWGA) operators may result in some unreasonable aggregated values in some cases. In order to overcome the drawbacks of the NCWAA and NCWGA, this paper developed a new neutrosophic cubic hybrid weighted arithmetic and geometric aggregation (NCHWAGA) operator and investigates its suitability and effectiveness. Then, we established a MADM method based on the NCHWAGA operator. Finally, a MADM problem with neutrosophic cubic information was provided to illustrate the application and effectiveness of the proposed method.
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Gulistan, Muhammad, Mutaz Mohammad, Faruk Karaaslan, Seifedine Kadry, Salma Khan, and Hafiz Abdul Wahab. "Neutrosophic cubic Heronian mean operators with applications in multiple attribute group decision-making using cosine similarity functions." International Journal of Distributed Sensor Networks 15, no. 9 (2019): 155014771987761. http://dx.doi.org/10.1177/1550147719877613.
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This article introduces the concept of Heronian mean operators, geometric Heronian mean operators, neutrosophic cubic number–improved generalized weighted Heronian mean operators, neutrosophic cubic number–improved generalized weighted geometric Heronian mean operators. These operators actually generalize the operators of fuzzy sets, cubic sets, and neutrosophic sets. We investigate the average weighted operator on neutrosophic cubic sets and weighted geometric operator on neutrosophic cubic sets to aggregate the neutrosophic cubic information. After this, based on average weighted and geometric weighted and cosine similarity function in neutrosophic cubic sets, we developed a multiple attribute group decision-making method. Finally, we give a mathematical example to illustrate the usefulness and application of the proposed method.
Dissertations / Theses on the topic "Average cubic"
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Deumal, Herraiz Marc. "Multicarrier communication systems with low sensibility to nonlinear amplification." Doctoral thesis, Universitat Ramon Llull, 2008. http://hdl.handle.net/10803/9137.
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Actualment estem entrant a una nova era de la informació amb gran demanda de sistemes de comunicació sense fils. Nous serveis com dades i video requereixen transmissions fiables d'alta velocitat, fins i tot en escenaris d'alta mobilitat. A més a més, la dificultat d'assignar el limitat espectre radioelèctric juntament amb la necessitat d'incrementar el temps de vida de les bateries dels terminals mòbils, requereix el diseny de transceptors que usin la potència i l'ampla de banda disponibles de manera eficient. Les comunicacions multiportadora basades en OFDM són capaces de satisfer la majoria d'aquests requeriments. Però, entre altres reptes, reduir la sensibilitat a la amplificació no-lineal és un factor clau durant el diseny. En aquesta tesi doctoral s'analitza la sensibilitat dels sistemes multiportadora basats en OFDM a l'amplificació no-lineal i es consideren formes eficients per superar aquest problema. La tesi s'enfoca principalment al problema de reduir les fluctuacions de l'envolupant del senyal transmès. En aquest sentit es presenta també un estudi de les mètriques de l'envolupant del senyal, PAPR i CM. A més a més, basant-nos en l'anàlisis presentat es proposen noves tècniques per sistemes OFDM i MC-SS. Per MC-SS, també es tracta el diseny d'una tècnica de postprocessament en forma de detector multiusuari per canals no-lineals.Actualmente estamos entrando en una nueva era de la información donde se da una gran demanda de sistemas de comunicación inalámbricos. Nuevos servicios como datos y vídeo requieren transmisiones fiables de alta velocidad, incluso en escenarios de alta movilidad. Además, la dificultad de asignar el limitado espectro radioeléctrico junto con la necesidad de incrementar el tiempo de vida de las baterías de los terminales móviles, requiere el diseño de transceptores que usen eficientemente la potencia y el ancho de banda disponibles. Las comunicaciones multiportadora basadas en OFDM son capaces de satisfacer la mayoría de dichos requerimientos. Sin embargo, entre otros retos, reducir su sensibilidad a la amplificación no-lineal es un factor clave durante el diseño. En esta tesis se analiza la sensibilidad de los sistemas multiportadora basados en OFDM a la amplificación no-lineal y se consideran formas eficientes para superar dicho problema. La tesis se enfoca principalmente al problema de reducir las fluctuaciones de la envolvente. En este sentido también se presenta un estudio de las métricas de la señal, PAPR y CM. Además, basándonos en el análisis presentado se proponen nuevas técnicas para OFDM y MC-SS. Para MC-SS, también se trata el diseño de un detector multiusuario para canales no-lineales.
We are now facing a new information age with high demand of wireless communication systems. New services such as data and video require achieving reliable high-speed transmissions even in high mobility scenarios. Moreover, the difficulty to allocate so many wireless communication systems in the limited frequency band in addition to the demand for long battery life requires designing spectrum and power efficient transceivers. Multicarrier communications based on OFDM are known to fulfill most of the requirements of such systems. However, among other challenges, reducing the sensitivity to nonlinear amplification has become a design key. In this thesis the sensitivity of OFDM-based multicarrier systems to nonlinear amplification is analyzed and efficient ways to overcome this problem are considered. The focus is mainly on the problem of reducing the envelope fluctuations. Therefore, a study of the signal metrics, namely PAPR and CM, is also presented. From the presented analysis, several new techniques for OFDM and MC-SS are proposed. For MC-SS, the design of a post-processing technique in the form of a multiuser detector for nonlinearly distorted MC-SS symbols is also addressed.
Books on the topic "Average cubic"
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Cai, Zongxi. Deng zhou wen ti. Ke xue chu ban she, 2002.
Book chapters on the topic "Average cubic"
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Rickard, David. "Framboid Microcrystal Growth." In Framboids. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780190080112.003.0012.
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Framboid microcrystals grow through surface reaction of S2(-II) or H2S with =FeS moieties at defect sites on the pyrite crystal surface. The surface energies of pyrite vary from the most stable cubic through octahedral to pyritohedral and dodecahedral surfaces. Microcrystals commonly develop as truncated octahedra as the supersaturation decreases during crystal growth in sedimentary environments, although cubic forms may be favored under hydrothermal conditions. Screw dislocation growth followed by surface nucleation growth are the normal growth modes in sediments, whereas surface nucleation growth is likely to dominate in hydrothermal systems. The rate of crystal growth of framboids is unknown but appears to be very fast and normally diffusion-limited. Linear approximations to the diffusion equations show that average 6 μm diameter framboids form in five days in sediments, and formation times increase exponentially from a few hours for ca. 2 μm framboids to three years for the largest 250 μm framboids.
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Swyngedouw, Erik. "Water, Power, and the Andean City: Situating Guayaquil." In Social Power and the Urbanization of Water. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780198233916.003.0014.
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There is no aggregate shortage of water in Latin America. The Amazon’s output into the Atlantic Ocean is about 150,000 cubic metres per second and a whole host of smaller rivers—the Magdalena, Orinoco, San Francisco, Uruguay, and Usumacinta rivers, to name but a few—all carry more than 1,000m3/sec of water into the ocean at their outlets. In contrast, Buenos Aires, Mexico City, and São Paulo, the three largest cities in Latin America, consume around 50 to 80m3/second, clearly a very small amount when compared to total available regional water resources (Anton 1993: 163). However, Mexico City is situated in an extremely water-scarce area, and other cities such as São Paulo, Brasilia, Guatemala City, Quito, and Bogota are located far from plentiful sources of water. Elsewhere, though, large cities and abundant water sources are in close proximity, yet large parts of their population still suffer from a lack of clean, cheap, and convenient water, a situation of scarcity in the midst of abundance. This chapter will examine the problems faced by the urban poor in Latin America in accessing potable water, and will examine the problems associated with its delivery. Although it contains some very arid areas such as the Atacama Desert, Latin America is a humid region. Until recently, water was regarded as an abundant resource, and justifiably so: Latin America’s annual precipitation is 60% above the world average and the average annual run-off of 370,000m3 is 30% of the world total (Biswas 1979: 16). A glance at water consumption levels in Latin American cities indicates no aggregate shortage of water. Table 3.1 suggests that average daily water consumption in Latin America’s big cities is comparable with that of cities in the developed world, and significantly higher than is the case in African and some Asian cities. Given that the very minimum amount of water deemed necessary to sustain life has been estimated at 5 litres per capita per day (LCD) (World Bank 1976), and that under most circumstances 30/40 LCD is deemed sufficient for a reasonable level of personal and community health (Kirke and Arthur 1987: 125), even the city with the lowest consumption level would appear to have a plentiful supply of water.
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Hu, Wentao, Yongjun Tian, and Zhongyuan Liu. "Carbon Vacancy Ordered Non-Stoichiometric ZrC0.6." In MAX Phases and Ultra-High Temperature Ceramics for Extreme Environments. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-4066-5.ch016.
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The starting nanopowders of non-stoichiometric zirconium carbide (ZrCx) were fabricated via milling Zr powders in toluene for different dwell times. The carbon content was determined to depend on the milling time and the used amount of toluene. The bulk non-stoichiometric ZrCx with different x were prepared by spark plasma sintering of the obtained ZrCx nanopowders. The microstructural features of a sintered ZrC0.6 sample were investigated via the measurements of XRD, TEM, and HRTEM. It was found that the carbon vacancies have an ordering arrangement in C sublattice, forming a Zr2C-type cubic superstructural phase with space group of Moreover, it was observed that the superstructural phase exists in nano-domains with an average size of ~30 nm owing to the ordering length in nanoscale. During the heating treatment in air, it was recognized that the diffusion of oxygen atoms is significantly facilitated through the ordered carbon vacancies. For the heating treatment at low temperature (<300°C), the oxygen atoms diffuse easily into and occupy the ordered carbon vacancies, forming the oxy-carbide of ZrC0.6O0.4 with ordered oxygen atoms. At the heating temperature higher than 350 °C an amorphous layer of ZrC0.6Oy>0.4 was identified to be formed due to the diffusion of superfluous oxygen atoms into Zr-tetrahedral centers. Inside the amorphous layer, the metastable tetragonal zirconia nanocrystals are recognized to be gradually developed.
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"Occupational Toxicology." In Environmental Toxicology, edited by Sigmund F. Zakrzewski. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195148114.003.0013.
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Industrial workers make up the segment of the population that is most vulnerable to chemical injury. To protect them from occupation-related harm, the American Conference of Governmental and Industrial Hygienists publishes annually revised threshold limit values (TLVs) (1), guidelines for permissible chemical exposure at the work place. TLV refers to concentrations of substances in parts per million or milligrams per cubic meter in the air to which most workers can be exposed on a daily basis without harm. These values apply to the work place only. They are not intended as guidelines for ambient air quality standards for the population at large. Obviously, genetic variations and diverse lifestyles (such as smoking, alcohol use, medication, and drug use) must be considered. Hypersensitive individuals may be adversely affected by exposure to certain chemicals even within the limits of the TLV. Thus, TLVs should be treated as guidelines only and not as fixed standards. The recommended goal is to minimize chemical exposure in the work place as much as possible. TLVs are expressed in three ways: 1. Time-weighted average (TLV–TWA) designates the average concentration of a chemical to which workers may safely be exposed for 8 h per day and 5 days per week. 2. Short-term exposure limit (TLV–STEL) designates permissible exposure for no more than 15 min, and no more than four times per day, with at least 60-min intervals between exposures. 3. Ceiling concentrations (TLV–C) are concentrations that should not be exceeded at any time. How protective the TLVs are is being questioned. The 1990 report that analyzed the scientific underpinnings of the TLVs revealed that at the exposure at or below the TLV, only few cases showed no adverse effect (2). In some cases even 100% of those exposed were affected. On the other hand, there was a good correlation between the TLVs and the measured exposure occurring in the work place. Thus, it appears that the TLVs represent levels of contaminants that may be encountered in the work place, rather than protective thresholds. Biological exposure indices (BEIs) provide another way of looking at exposure to chemicals.
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Armstrong, Ronald W. "Hall–Petch Relationship in Aluminum and Aluminum Alloys." In Encyclopedia of Aluminum and Its Alloys. CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000234.
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The mechanical properties of aluminum are shown to be of special importance beginning from the early 20th-century production of the material in single crystal and polycrystalline form. Experimental and theoretical researches of the time were concerned with particular influence of polycrystalline microstructure and the presence of crystal (grain) boundaries on both the material strength properties and on relation of those same properties to those for the full range of metal and alloy structures. Now it is well established that a relatively low value of the microstructural stress intensity, kε, is obtained for aluminum in the generalized Hall–Petch relation for its stress–strain, σε − ε, behavior depending on the average grain diameter, l, with intercept (friction) stress, σ0ε, which relation is given as: id="unequ63_1">σε=σ0ε+kεl−1/2With hindsight, taking σε = σ0ε provided the first connection between single crystal and polycrystalline strength measurements in the pioneering Taylor theory of plasticity proposed for aluminum and other face-centered cubic metals. Later, conventional and ultrafine grain size measurements are shown to verify the fuller H–P dependence. The present account builds onto the early history. A description is given for temperature, strain rate, and alloy-dependent mechanical property measurements. An understanding of the total measurements is described in terms of a dislocation pile-up model description for the relation. Emphasis is given to kε for pure aluminum and related metals being determined by cross-slip forced at grain boundaries. Particular attention is given to two characteristics of the metal mechanical behavior: (1) very high rate loading deformations leading to shock and shock-less isentropic compression experiments and (2) important grain size influences on nanopolycrystalline material behaviors. Additional results are presented on H–P aspects of the material strain ageing, shear banding, ductile fracturing, and fatigue behaviors.
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García, Mario, Héctor Ulloa, Omar García, et al. "Particle and Carbon Monoxide Atmospheric Pollution in the City of Tepic, Nayarit, Mexico." In Environmental Sustainability - Preparing for Tomorrow. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95579.
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Actively caring for the environment is an issue that prevails in the international debate, and our country takes part on this argument. One aspect of environmental deterioration is, with no doubt, atmospheric pollution; a constant in modern societies, which, in the attempt to find growth and development, impact the natural and urban environment they inhabit. A distinctive feature of commercial and economic exchange are the strategic cities, so-called capitals, in addition to the territories where coastal tourism predominates as an engine of regional human development. In this balance, which is far from being sustainable and fair, an exponential consumer market dominates and generates the progressive increase in the use of fossil fuels. The former being emitted into the atmosphere, in such a way that they alter chemical composition and cause harmful air quality. In addition, the territory is impacted, intoxicating the soil and water, which are the final deposit. The objective of this work is to determine the temporal behavior of atmospheric pollutants in the city of Tepic, Nayarit, Mexico and to identify the dominant pollution indicators considering the international and national context. Through the statistical analysis of the databases of particles smaller than 2.5 micrometers, particles smaller than 10 micrometers and carbon monoxide, the behaviors of these pollutants in the study area were obtained. Among the most significant results, particles smaller than 2.5 micrometers showed maximum levels outside the norm almost all year round, with values reaching 170 micrograms per cubic meter. On the other hand, the particles smaller than 10 micrometers presented satisfactory levels in their average behavior; however, the maximum concentrations remained outside the official Mexican standard. Regarding the analysis of CO, a behavior within the maximum permissible limits of protection for the population was reported; Nevertheless, by favoring the formation of tropospheric ozone, its contribution is significant, especially when the atmosphere is highly photo-reactive. This research can be used as a timely tool for mitigation of climate change, where the results contribute to the review and rethinking of public management of the environment towards sustainable development.
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"Uniformity seminorms on ℓ^{∞} and pointwise convergence of cubic averages." In Mathematical Surveys and Monographs. American Mathematical Society, 2018. http://dx.doi.org/10.1090/surv/236/22.
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Sumalatha, Edapalli, Dachepalli Ravinder, Nyathani Maramu, et al. "Crystal Chemistry, Rietveld Analysis, Structural and Electrical Properties of Cobalt-Erbium Nano-Ferrites." In Ferrite [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98864.
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Synthesis of Cobalt-Erbium nano-ferrites with formulation CoErxFe2-xO4 (x = 0, 0.005, 0.010, 0.015, 0.020, 0.025, and 0.030) using technique of citrate-gel auto-combustion was done. Characterization of prepared powders was done by using XRD, EDAX, FESEM, AFM and FTIR Spectroscopy, DC resistivity properties respectively. XRD Rietveld Analysis, SEM, TEM and EDAX analysis were taken up in studying spectral, structural, magnetic and electrical properties. XRD pattern of CEF nano particles confirm single phase cubic spinal structure. The structural variables given by lattice constant (a), lattice volume (v), average crystallite size (D) and X-ray density(dx), Bulk density (d), porosity (p), percentage of pore space (P%), surface area (s), strain (ε), dislocation density (δ), along with ionic radii, bond length and hoping length were calculated. SEM and TEM results reveal homogeneous nature of particles accompanied by clusters having no impurity pickup. TEM analysis gives information about particle size of nanocrystalline ferrite while EDAX analysis confirm elemental composition. Emergence of two arch shaped frequency bands (ν1 and ν2) that represent vibrations at tetrahedral site (A) and octahedral site(B) was indicated by spectra of FTIR. The samples electrical resistivity (DC) was measured between 30°C -600°C with Two probe method. XRD Rietveld analysis confirm crystallite size lying between 20.84 nm–14.40 nm while SEM analysis indicate formation of agglomerates and TEM analysis indicate particle size ranging between 24 nm–16 nm. DC Electrical measurements indicate continuous decrease in resistivity with increasing temperature while increasing doping decreases curie temperature. The Magnetic parameters such as Saturation magnetization (Ms), Remanent magnetization (Mr), Coercivity (Hc) and Squareness ratio (R = Mr/Ms), Magnetic moment (nB) were altered by doping of Er+3 content in the increasing order (x = 0.00 to 0.030). The increasing erbium content decreases magnetization thus converting the sample into soft magnetic material. Observations indicated strong dependence of magnetic properties on Erbium substitution and coercivity varies in accordance with anisotropy constant. Due to the presence of magnetic dipole Erbium substituted cobalt ferrites can be used in electromagnetic applications. The present study investigates the effect of different compositions of Er3+ replaced for Fe on structural properties and electrical resistivity of cobalt ferrites.
Conference papers on the topic "Average cubic"
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Peng, D. Y., X. H. Niu, X. H. Tang, and Q. C. Chen. "The Average Hamming Correlation for the Cubic Polynomial Hopping Sequences." In 2008 International Wireless Communications and Mobile Computing Conference (IWCMC). IEEE, 2008. http://dx.doi.org/10.1109/iwcmc.2008.81.
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Hur, Soojung C., Laurent Pilon, Adam Christensen, and Samuel Graham. "Thermal Conductivity of Cubic Mesoporous Silica Thin Films." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-43016.
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This paper reports, for the first time, the cross-plane thermal conductivity of highly ordered cubic mesoporous silica thin films with porosity of 31% and thickness ranging between 200 and 500 nm. The mesoporous thin films are synthesized based on evaporation induced self-assembly process. The pores are spherical with average inter-pore spacing and pore diameter equal to 5.95 nm and 5 nm, respectively. The thermal conductivity is measured at room temperature using the 3ω method. The experimental setup and the associated analysis are validated by comparing the thermal conductivity measurements for the silicon substrate and for high quality thermal oxide thin films with data reported in the literature. The cross-plane thermal conductivity of the synthesized mesoporous silica thin films does not strongly depend on film thickness due to the reduction in phonon mean free path caused by the presence of nanopores. The average thermal conductivity is 0.61 ± 0.011 W/mK, which is 56% lower than that of bulk fused silica at room temperature.
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Dzodzo, Milorad B. "Natural Convection in Cubic and Rhomb-Shaped Enclosures." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17724.
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Laminar natural convection in cubic and rhomb–shaped enclosures (rhomb angles 59°, 44° and 28.2°) with two opposite vertical walls kept at different temperatures was investigated experimentally and numerically. The enclosures were filled with glycerol and the Rayleigh (Ra) and Prandtl (Pr) numbers ranged from 2,000<Ra<369,000 and 2,680<Pr<7,000. The visualization of the velocity and temperature fields was obtained by using Plexiglass and liquid crystal particles as tracers. The finite volume method based on the finite difference approach was applied for numerical analysis. The velocity and temperature fields and average Nusselt numbers were found as a function of the Reyleigh and Prandtl numbers. Comparison of the average Nusselt numbers for cubic and rhomb-shaped enclosures indicates decrease of heat transfer for the cases when the lower and upper vertical walls of the rhomb-shaped enclosures are at lower and higher temperatures, respectively. This is due to the tendency of fluid stratification in the lower and upper corners.
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Coquil, Thomas, Neal Hutchinson, Laurent Pilon, Erik Richman, and Sarah Tolbert. "Thermal Conductivity of Cubic and Hexagonal Mesoporous Silica Thin Films." In ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88256.
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This paper reports the cross-plane thermal conductivity of highly ordered cubic and hexagonal templated mesoporous amorphous silica thin films synthesized by evaporation-induced self-assembly process. Cubic and hexagonal films featured spherical and cylindrical pores and average porosity of 25% and 45%, respectively. The pore diameter ranged from 3 to 18 nm and film thickness from 80 to 540 nm while the average wall thickness varied from 3 to 12 nm. The thermal conductivity was measured at room temperature using the 3ω method. The experimental setup and the associated analysis were validated by comparing the thermal conductivity measurements with data reported in the literature for the silicon substrate and for high quality thermal oxide thin films with thickness ranging from 100 to 500 nm. The cross-plane thermal conductivity of the synthesized mesoporous silica thin films does not show strong dependence on pore size, wall thickness, or film thickness. This is due to the fact that heat is mainly carried by very localized non propagating vibrational modes. The average thermal conductivity for the cubic mesoporous silica films was 0.30 ± 0.02 W/mK, while it was 0.20 ± 0.01 W/mK for the hexagonal films. This corresponds to a reduction of 79% and 86% from bulk fused silica at room temperature.
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Kulkarni, Nitin Nagesh, Stephen Ekwaro-Osire, and Paul F. Egan. "Mechanical Testing and Reliability Analysis for 3D Printed Cubic Lattices." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23694.
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Abstract 3D printing has enabled new avenues to design and fabricate diverse structures for engineering applications, such as mechanically efficient lattices. Lattices are useful as implants for biological applications for supporting in vivo loads. However, inconsistencies in 3D printing motivates a need to quantify uncertainties contributing to mechanical failure using probabilistic analysis. Here, 50 cubic unit cell lattice samples were printed and tested with designs of 50% porosity, 500-micron beam diameters, and 3.5mm length, width, and height dimensions. The average length, width, and height measurements ranged from 3.47mm to 3.48mm. The precision in printing with a 95% confidence level was greater than 99.8%. Lattice elastic moduli ranged from about 270 MPa to 345 MPa, with a mean of 305 MPa. Probabilistic analyses were conducted with NESSUS software. The distributions of input parameters were determined using a chi-square test. The first-order reliability method was used to calculate the probability of failure and sensitivity of each input parameter. The elastic modulus was the most sensitive among all input parameters, with 57% of the total sensitivity. The study quantified printing inconsistencies and sensitives using empirical evidence and is a significant step forward for designing 3D printed parts for mechanical applications.
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Mofakham, Amir A., Goodarz Ahmadi, Matthew Stadelman, Kevin Shanley, and Dustin Crandall. "Study of Transmissivity of a Fracture Under Shearing." In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83348.
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A Marcellus shale rock fracture was subjected to four shearing steps and at the end of each shearing step CT (computed tomography) scans with resolution of 26.8 μm were obtained. The CT images were used to generate full aperture maps of the fracture configuration at the end of each shearing phase. The pressure drops along the fracture were also measured for different water flow rates through the fracture. The aperture map of the fracture was used to generate the geometry of the fracture for use in numerical simulations. The water flows and pressure drops in the fracture were simulated with different computational methods that included the full Navier-Stokes simulation, Modified Local Cubic Law (MLCL), and Improved Cubic Law (ICL) methods. Full 3-D Navier-Stokes simulation is the most accurate computational approach which was done with use of the ANSYS-Fluent software for each shear step and different flow rates. The MLCL is a 2-D relatively fast method which is commonly used for prediction of transmissivity of fractures. ICL is a 1-D method proposed in this study in which the effects of surface roughness and tortuosity were included in calculation of the effective aperture height of fractures. To provide an understanding of the accuracy of each of these models their predictions were compared with each other and with the experimental data. Also, to examine the effects of resolution of CT scans and the surface roughness on prediction of fractures transmissivity, similar simulations were performed on average aperture maps. Here the fracture of the full resolution data was averaged over 10 × 10 pixels. Comparing the results of the average aperture maps with those of the full maps showed that the lower resolution of CT scans led to underestimation of the fracture pressure drop due to missing the small features of the fracture surfaces and smoothing out their roughness.
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Oriji, Ugochukwu R., and Paul G. Tucker. "RANS Modelling of Accelerating Boundary Layers." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63467.
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A numerical investigation of accelerated boundary layers (BL) has been performed using linear and non-linear eddy viscosity models (EVM). The acceleration parameters (KS) investigated range between 1.5×10−6 and 3.0×10−6. The one equation (k-l), Spalart Allmaras (SA) and the two-equation Menter SST and Chien models in their standard forms are found to be insensitive to acceleration. Nevertheless, proposed modifications for the SA, Chien and the k-l models significantly improved predictions. The major improvement was achieved by modifying the damping functions in these models and also an analogous source term, E, for the Chien model. Encouraging agreement with measurements is found using the Launder Sharma (LS), Cubic and Explicit Algebraic Stress Models (EASM) in their standard forms. The cubic model best predicted the turbulence quantities. Investigations confirm that it is practical for Reynolds Average Navier-Stokes (RANS) models to capture reversion from the turbulent to laminar state albeit for equilibrium sink type flows.
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FREIMANE, Lāsma, and Mārtiņš AILTS. "RESPONSE REACTION OF SCOTS PINE PINUS SYLVESTRIS L. AFTER FOREST FIRE IN FOREST SITE TYPE HYLOCOMIOSA." In Rural Development 2015. Aleksandras Stulginskis University, 2015. http://dx.doi.org/10.15544/rd.2015.072.
Full textAbstract:
Many factors explain the importance of the research: role of forest industry in Latvian national economy, predicted climate changes in future that foresee better conditions for forest fires, and the fact that until this moment in Latvia there is very little research about radial growth dynamic after forest fire. Object of the research is surface fire affected middle-age managed Scots pine stands in forest site type Hylocomiosa. The empirical material was collected in 500 m2 large circular sample plots in both fire affected and fire unaffected parts of forest stands. At sample plots, dendrometric parameters of trees were measured. After low to medium intensity surface fire forest stand radial growth dynamics is positive, but effect of forest fire impact is negligible – in six year period six cubic meters per hectare or in average one cubic meter per hectare per year. Forest fire significantly does not affect mortality of trees in middle-age Scots pine forest stand in forest site type Hylocomiosa, p = 0.19 > α= 0.05. Minimal financial loss as result of deadwood volume after forest fire is 2179.00 EUR ha-1.
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Flores, J. J., and G. Alvarez. "Experimental Performance of Natural Convection of a Semitransparent Wall With Film Coating of a Cubic Enclosure Using Infrared Imaging." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33152.
Full textAbstract:
This paper presents an experimental heat transfer study of the exterior side of a semitransparent wall (window) with film coating of a enclosure. The absorptance of the semitransparent wall with film coating was simulated using a film resistance on the glazing. A technique of infrared imagining thermography and a traversing system developed in Lawrence Berkeley National Laboratories (LBNL) were extended to measured from 1-D to 2-D local surface temperatures and boundary layer air temperatures of the exterior a glazing. From those measurements, the exterior heat flow and the exterior local convective heat transfer coefficients were calculated by applying a technique proposed by Truler [1]. The 2-D surface temperature distributions, the local convective heat transfer coefficient distributions and the average Nusselt number of the exterior side of the semitransparent wall with a simulated absorptance of 0.5 are presented.
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Kim, Jeong Sik, Anastasia Muliana, and Kamran Khan. "A Homogenization Scheme for Nonlinear Viscoelastic Behaviors of Particulate Reinforced Composites." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-13598.
Full textAbstract:
The present study introduces a micromechanical model for predicting nonlinear viscoelastic responses of composite systems reinforced with solid spherical micro particles. The composite microstructures are simplified with uniformly distributed cubic particles over an infinite medium. The representative volume element (RVE) consists of a single particle embedded in the cubic matrix. One eighth unit-cell model with four particle and polymer subcells is generated. The solid spherical particle is modeled as linear elastic, while the polymer follows nonlinear viscoelastic material responses. The homogenized micromechanical relation is developed in terms of the average strains and stresses and satisfies traction continuity and displacement compatibility at the subcells' interfaces. The micromechanical model provides three-dimensional (3D) effective properties of homogeneous materials, while recognizing important micro-structural aspects and parameters of the heterogeneous medium. The micromechanical formulation is generalized to include an explicit time-scale for modeling time-dependent behavior and is designed to be compatible with general displacement based finite element (FE) analyses. Due to the nonlinear and time-dependent response in the polymeric matrix, the linearized micromechanical relations will often deviate from the nonlinear constitutive equations. Thus, the stress-strain correction scheme is formulated to satisfy both micromechanical and nonlinear constitutive relations. Experimental data and analytical models available in the literature are used to verify the capability of the above micromechanical model in predicting the overall nonlinear behaviors. Comparisons with detail unit-cell FE model are also presented.