Search results for: critical transformation temperature

Authors: Yang Geng, Anqi Zhao

Abstract:

The misreading theory of Harold Bloom provides a new diachronic perspective as an approach to the consistency between rhetoric of digital technology, dynamic movement of digital images and uncertain meaning of text. Reinterpreting the diachroneity of 'intertextuality' in the context of misreading theory extended the range of the 'intermediality' of transmedia to the intense tension between digital images and symbolic images throughout history of images. With the analogy between six categories of revisionary ratios and six steps of digital transformation, digital rhetoric might be illustrated as a linear process reflecting dynamic, intensive relations between digital moving images and original static images. Finally, it was concluded that two-way framework of the rhetoric of transformation of digital images and reversed served as a renarrative structure to revive static images by reconnecting them with digital moving images.

Keywords: rhetoric, digital art, intermediality, misreading theory

Procedia PDF Downloads 237

Authors: Perttu Heino

Abstract:

Universities of applied sciences (UASs) were introduced as part of the Finnish higher education system in the early 1990’s. Research, development and innovation (RDI) were mentioned in the legislation on UASs from the very beginning, but very little attention was paid to it in the early years of UASs due to reasons that are easy to understand. Required changes in the organization of the UAS and its educational offering were a big challenge, and it took several years to get things in order. There were RDI projects already then, but their number was low and there was no systematical coordination or management of those activities. In this paper, the institutional transformation of UASs is discussed based on how Tampere University of Applied Sciences has transformed during the years from a traditional tertiary level school to a modern higher education institution with a strong RDI activity, characterized by lively university-industry interaction and tight integration to education.

Keywords: research, development, management, practices

Procedia PDF Downloads 27

Authors: Magda Silva

Abstract:

This paper presents the sociocultural and critical theories used in the creation of a study abroad program in Brazil, as well as the successful results obtained in the fourteen years of experience provided by the program in distinct regions of Brazil. This program maximizes students’ acquisition of the Portuguese language, and affords them an in-depth intercultural and intracultural competence by on site studies in cosmopolitan Rio de Janeiro, afro-heritage Salvador da Bahia, and Amazonian Belém do Pará. The program provides the means to acknowledge the presence, influence, similarities, and differences of Portuguese-speaking Brazil in Latin America.

Keywords: study abroad, critical thinking, sociocultural theory, foreign language, empirical, theoretical

Procedia PDF Downloads 405

Authors: Erhan Ayas, Buse Katipoğlu, Eda Metin, Rifat Yılmaz

Abstract:

The search for new materials has begun to be used even higher than the service temperature (~1150ᵒC) where nickel-based superalloys are currently used. This search should also meet the increasing demands for energy efficiency improvements. The materials studied for aerospace applications are expected to have good oxidation resistance. Mo-Si-B alloys, which have higher operating temperatures than nickel-based superalloys, are candidates for ultra-high temperature materials used in gas turbine and jet engines. Because the Moss and Mo₅SiB₂ (T2) phases exhibit high melting temperature, excellent high-temperature creep strength and oxidation resistance properties, however, low fracture toughness value at room temperature is a disadvantage for these materials, but this feature can be improved with optimum Moss phase and microstructure control. High-density value is also a problem for structural parts. For example, in turbine rotors, the higher the weight, the higher the centrifugal force, which reduces the creep life of the material. The density value of the nickel-based superalloys and the T2 phase, which is the Mo-Si-B alloy phase, is in the range of 8.6 - 9.2 g/cm³. But under these conditions, T2 phase Moss (density value 10.2 g/cm³), this value is above the density value of nickel-based superalloys. So, with some ceramic-based contributions, this value is enhanced by optimum values.

Keywords: molybdenum, composites, in-situ, mmc

Procedia PDF Downloads 49

Authors: B. V. Feujofack Kemda, N. Barka, M. Jahazi, D. Osmani

Abstract:

Automobile manufacturers are constantly seeking means to reduce the weight of car bodies. The usage of several steel grades in auto body assembling has been found to be a good technique to enlighten vehicles weight. This few years, the usage of dual phase (DP) steels, transformation induced plasticity (TRIP) steels and boron steels in some parts of the auto body have become a necessity because of their lightweight. However, these steels are martensitic, when they undergo a fast heat treatment, the resultant microstructure is essential, made of martensite. Resistance spot welding (RSW), one of the most used techniques in assembling auto bodies, becomes problematic in the case of these steels. RSW being indeed a process were steel is heated and cooled in a very short period of time, the resulting weld nugget is mostly fully martensitic, especially in the case of DP, TRIP and boron steels but that also holds for plain carbon steels as AISI 1010 grade which is extensively used in auto body inner parts. Martensite in its turn must be avoided as most as possible when welding steel because it is the principal source of brittleness and it weakens weld nugget. Thus, this work aims to find a mean to reduce martensite fraction in weld nugget when using RSW for assembling. The prediction of phase transformation kinetics during RSW has been done. That phase transformation kinetics prediction has been made possible through the modelling of the whole welding process, and a technique called post weld heat treatment (PWHT) have been applied in order to reduce martensite fraction in the weld nugget. Simulation has been performed for AISI 1010 grade, and results show that the application of PWHT leads to the formation of not only martensite but also ferrite, bainite and pearlite during the cooling of weld nugget. Welding experiments have been done in parallel and micrographic analyses show the presence of several phases in the weld nugget. Experimental weld geometry and phase proportions are in good agreement with simulation results, showing here the validity of the model.

Keywords: resistance spot welding, AISI 1010, modeling, post weld heat treatment, phase transformation, kinetics

Procedia PDF Downloads 98

Authors: M. Ba-Shammakh

Abstract:

Metal-organic frameworks (MOFs) are promising materials for CO₂ capture and they have high adsorption capacity towards CO₂. In this study, two different metal organic frameworks (i.e. MIL-101 and ZIF-301) were tested for different flue gases that have different CO₂ fractions. In addition, the effect of temperature was investigated for MIL-101 and ZIF-301. The results show that MIL-101 performs well for pure CO₂ stream while its intake decreases dramatically for other flue gases that have variable CO₂ fraction ranging from 5 to 15 %. The second material (ZIF-301) showed a better result in all flue gases and higher CO₂ intake compared to MIL-101 even at high temperature.

Keywords: CO₂ capture, Metal Organic Frameworks (MOFs), MIL-101, ZIF-301

Procedia PDF Downloads 174

Authors: Khatia Tavidashvili, Nino Jamrishvili, Valerian Omsarashvili

Abstract:

Studies of the vertical distribution of the air temperature in the atmosphere have great value for the solution of different problems of meteorology and climatology (meteorological forecast of showers, thunderstorms, and hail, weather modification, estimation of climate change, etc.). From the end of May 2015 in Kakheti after 25-year interruption, the work of anti-hail service was restored. Therefore, in connection with climate change, the need for the detailed study of the contemporary regime of the vertical distribution of the air temperature above this territory arose. In particular, the indicated information is necessary for the optimum selection of rocket means with the works on the weather modification (fight with the hail, the regulation of atmospheric precipitations, etc.). Construction of the detailed maps of the potential damage distribution of agricultural crops from the hail, etc. taking into account the dimensions of hailstones in the clouds according to the data of radar measurements and height of locality are the most important factors. For now, in Georgia, there is no aerological probing of atmosphere. To solve given problem we processed information about air temperature profiles above Telavi, at 27 km above earth's surface. Information was gathered during four observation time (4, 10, 16, 22 hours with local time. After research, we found vertical distribution of the average monthly values of the air temperature above Kakheti in ‎2012-2017 from January to December. Research was conducted from 0.543 to 27 km above sea level during four periods of research. In particular, it is obtained: -during January the monthly average air temperature linearly diminishes with 2.6 °C on the earth's surface to -57.1 °C at the height of 10 km, then little it changes up to the height of 26 km; the gradient of the air temperature in the layer of the atmosphere from 0.543 to 8 km - 6.3 °C/km; height of zero isotherm - is 1.33 km. -during July the air temperature linearly diminishes with 23.5 °C to -64.7 °C at the height of 17 km, then it grows to -47.5 °C at the height of 27 km; the gradient of the air temperature of - 6.1 °C/km; height of zero isotherm - is 4.39 km, which on 0.16 km is higher than in the sixties of past century.

Keywords: hail, Kakheti, meteorology, vertical distribution of the air temperature

Procedia PDF Downloads 153

Authors: B. Arzhanov, A. Correia, P. Delgado, J. Meireles

Abstract:

Quad Flat No-Lead (QFN) packages have become very popular for turners, converters and audio amplifiers, among others applications, needing efficient power dissipation in small footprints. Since semiconductor junction temperature (TJ) is a critical parameter in the product quality. And to ensure that die temperature does not exceed the maximum allowable TJ, a thermal analysis conducted in an earlier development phase is essential to avoid repeated re-designs process with huge losses in cost and time. A simulation tool capable to estimate die temperature of components with QFN package was developed. Allow establish a non-empirical way to define an acceptance criterion for amount of voids in solder interface between its exposed pad and Printed Circuit Board (PCB) to be applied during industrialization process, and evaluate the impact of PCB designs parameters. Targeting PCB layout designer as an end user for the application, a user-friendly interface (GUI) was implemented allowing user to introduce design parameters in a convenient and secure way and hiding all the complexity of finite element simulation process. This cost effective tool turns transparent a simulating process and provides useful outputs after acceptable time, which can be adopted by PCB designers, preventing potential risks during the design stage and make product economically efficient by not oversizing it. This article gathers relevant information related to the design and implementation of the developed tool, presenting a parametric study conducted with it. The simulation tool was experimentally validated using a Thermal-Test-Chip (TTC) in a QFN open-cavity, in order to measure junction temperature (TJ) directly on the die under controlled and knowing conditions. Providing a short overview about standard thermal solutions and impacts in exposed pad packages (i.e. QFN), accurately describe the methods and techniques that the system designer should use to achieve optimum thermal performance, and demonstrate the effect of system-level constraints on the thermal performance of the design.

Keywords: QFN packages, exposed pads, junction temperature, thermal management and measurements

Procedia PDF Downloads 239

Authors: Ken Ninez Nurpramesti Prinindya, Yuli Setiyorini

Abstract:

Crown enclosure high temperature flares damaged and reduced dimensions crown. Generally crown on EHTF could have a life time up to twenty years. Therefore, this study aims to increase the value of thermal resistance with the effect post treatment on NiCr coated arc spray method. The variation of post treatment temperature, was at 650°C, 750°C, and 850°C. Morphology on the surface and the adhesion strength was analyzed by SEM-EDX, Surface Roughness and Pull - off test. XRD testing was conducted to determine the contained in NiCr coated. Thermal stability of NiCr coated was tested by DSC-TGA. The most optimal results was owned by NiCr coating with post treated at 850°C. It has good thermal stability until 1000°C because of Cr2O3 formation in coated specimen. The higher temperature of post treatment coating was showed better result on porosity and roughness surface value.

Keywords: Arc spray process, NiCr wire, post-treatment coating, high temperature-corrosion resistance

Procedia PDF Downloads 451

Authors: Tero Huhtala, Minna Pikkarainen, Saila Saraniemi

Abstract:

Information technology has long been used as an enabler of exchange for goods and services. Services are evolving from generic to personalized, and the reverse use of customer data has been discussed in both academia and industry for the past few years. This article presents the results of an empirical case study in the area of preventive health care services. The primary data were gathered in workshops, in which future personal data-based services were conceptualized by analyzing future scenarios from a business perspective. The aim of this study is to understand business model transformation in emerging personal data ecosystems. The work was done as a case study in the context of occupational healthcare. The results have implications to theory and practice, indicating that adopting personal data management principles requires transformation of the business model, which, if successfully managed, may provide access to more resources, potential to offer better value, and additional customer channels. These advantages correlate with the broadening of the business ecosystem. Expanding the scope of this study to include more actors would improve the validity of the research. The results draw from existing literature and are based on findings from a case study and the economic properties of the healthcare industry in Finland.

Keywords: ecosystem, business model, personal data, preventive healthcare

Procedia PDF Downloads 231

Authors: Claire M. Hollocou, Denise Johnson

Abstract:

As racism permeates the foundation of America's educational system, educators hold a level of responsibility to address racism and the power of white privilege in the classroom by implementing anti-racist practices. This study aims to discuss the practices of anti-racist education across two predominantly affluent white schools. It offers our perspectives as white and black female teachers committed to implementing and reflecting on our antiracist work. Through communities of practice and the critical dialogue framework, we will provide an environment for one another to share our experiences implementing anti-racist education. We will spend a couple of months engaging in dialogue together to support our praxis. With critical reflection, we will look for themes that emerge through the conversations as well as develop a protocol for building an antiracist community of practice. This study is a work in progress.

Keywords: anti-racism, critical dialogue, race and racism, teacher education

Procedia PDF Downloads 116

Authors: Lukas J. Evans, Danilo D. Fernando

Abstract:

Shrub willows (Salix spp.) have many characteristics which make them suitable for a variety of applications such as riparian zone buffers, environmental contaminant sequestration, living snow fences, and biofuel production. In some cases, these functions are limited due to physical or financial obstacles associated with the number of individuals needed to reasonably satisfy that purpose. One way to increase the efficiency of willows is to bioengineer them with the genetic improvements suitable for the desired use. To accomplish this goal, an optimized in vitro transformation protocol via Agrobacterium tumefaciens is necessary to reliably express genes of interest. Therefore, the aim of this study is to observe the influence of tissue culture with different willow cultivars, hormones, and explants on the percentage of calli expressing reporter gene green florescent protein (GFP) to find ideal transformation conditions. Each callus was produced from 1 month old open-pollinated seedlings of three Salix miyabeana cultivars (‘SX61’, ‘WT1’, and ‘WT2’) from three different explants (lamina, petiole, and internodes). Explants were cultured for 1 month on an MS media with different concentrations of 6-Benzylaminopurine (BAP) and 1-Naphthaleneacetic acid (NAA) (No hormones, 1 mg⁻¹L BAP only, 3 mg⁻¹L NAA only, 1 mg⁻¹L BAP and 3 mg⁻¹L NAA, and 3 mg⁻¹L BAP and 1 mg⁻¹L NAA) to produce a callus. Samples were then treated with Agrobacterium tumefaciens at an OD600 of 0.6-0.8 to insert the transgene GFP for 30 minutes, co-cultivated for 72 hours, and selected on the same media type they were cultured on with added 7.5 mg⁻¹L of Hygromycin for 1 week before GFP visualization under a UV dissecting scope. Percentage of GFP expressing calli as well as the average number of fluorescing GFP units per callus were recorded and results were evaluated through an ANOVA test (α = 0.05). The WT1 internode-derived calli on media with 3 mg-1L NAA+1 mg⁻¹L BAP and mg⁻¹L BAP alone produced a significantly higher percentage of GFP expressing calli than each other group (19.1% and 19.4%, respectively). Additionally, The WT1 internode group cultured with 3 mg⁻¹L NAA+1 mg⁻¹L BAP produced an average of 2.89 GFP units per callus while the group cultivated with 1 mg⁻¹L BAP produced an average of 0.84 GFP units per callus. In conclusion, genotype, explant choice, and hormones all play a significant role in increasing successful transformation in willows. Future studies to produce whole callus GFP expression and subsequent plantlet regeneration are necessary for a complete willow transformation protocol.

Keywords: agrobacterium, callus, Salix, tissue culture

Procedia PDF Downloads 108

Authors: Ozan Kahraman, Hao Feng

Abstract:

Manothermosonication (MTS), which consists of the simultaneous application of heat and ultrasound under moderate pressure (100-700 kPa), is one of the technologies which destroy microorganisms and inactivates enzymes. Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through an ultra-thin specimen, interacting with the specimen as it passes through it. The environmental scanning electron microscope or ESEM is a scanning electron microscope (SEM) that allows for the option of collecting electron micrographs of specimens that are "wet," uncoated. These microscopy techniques allow us to observe the processing effects on the samples. This study was conducted to investigate the effects of MTS and HTST treatments on the morphology of apple-carrot juices by using TEM and ESEM microscopy. Apple-carrot juices treated with HTST (72 0C, 15 s), MTS 50 °C (60 s, 200 kPa), and MTS 60 °C (30 s, 200 kPa) were observed in both ESEM and TEM microscopy. For TEM analysis, a drop of the solution dispersed in fixative solution was put onto a Parafilm ® sheet. The copper coated side of the TEM sample holder grid was gently laid on top of the droplet and incubated for 15 min. A drop of a 7% uranyl acetate solution was added and held for 2 min. The grid was then removed from the droplet and allowed to dry at room temperature and presented into the TEM. For ESEM analysis, a critical point drying of the filters was performed using a critical point dryer (CPD) (Samdri PVT- 3D, Tousimis Research Corp., Rockville, MD, USA). After the CPD, each filter was mounted onto a stub and coated with gold/palladium with a sputter coater (Desk II TSC Denton Vacuum, Moorestown, NJ, USA). E.Coli O157:H7 cells on the filters were observed with an ESEM (Philips XL30 ESEM-FEG, FEI Co., Eindhoven, The Netherland). ESEM (Environmental Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) images showed extensive damage for the samples treated with MTS at 50 and 60 °C such as ruptured cells and breakage on cell membranes. The damage was increasing with increasing exposure time.

Keywords: MTS, HTST, ESEM, TEM, E.COLI O157:H7

Procedia PDF Downloads 267

Authors: Ju-young Hwang, Hyo-Gyoung Kwak, Hong Jae Yim

Abstract:

This paper introduces a numerical analysis method for reinforced-concrete (RC) structures exposed to fire and compares the result with experimental results. The proposed analysis method for RC structure under the high temperature consists of two procedures. First step is to decide the temperature distribution across the section through the heat transfer analysis by using the time-temperature curve. After determination of the temperature distribution, the nonlinear analysis is followed. By considering material and geometrical non-linearity with the temperature distribution, nonlinear analysis predicts the behavior of RC structure under the fire by the exposed time. The proposed method is validated by the comparison with the experimental results. Finally, Prediction model to describe the status of after-cooling concrete can also be introduced based on the results of additional experiment. The product of this study is expected to be embedded for smart structure monitoring system against fire in u-City.

Keywords: RC structures, heat transfer analysis, nonlinear analysis, after-cooling concrete model

Procedia PDF Downloads 351

Authors: Ramovatar, Neeraj Panwar

Abstract:

Lead free Ba₀.₉₈Ca₀.₀₂SnxTi₁₋ₓO₃ (x = 0.01 and 0.05 mole %) ferroelectric ceramics have been synthesized by the solid-state reaction method with sintering at 1400 °C for 2 h. The room temperature x-ray diffraction (XRD) patterns identified the tetragonal phase for x = 0.01 composition whereas co-existence of tetragonal and orthorhombic phases for x =0.05 composition. Raman spectroscopy results corroborated with the XRD results at room temperature. The maximum dielectric properties (ɛm ~ 8591, tanδ ~ 0.018) were obtained for the compound with x = 0.01 at 5 kHz. Further, the tetragonal to cubic (TC) transition temperature was observed at 122 °C and 102 °C for the ceramics with x =0.01 and x = 0.05, respectively. The temperature dependent P-E loops also revealed the existence of TC at these particular temperature values. The energy storage density (Ed) of both compounds was calculated from room temperature P – E loops at an applied electric field of 20 kV/cm. The maximum Ed ~ 224 kJ/m³ was achieved for the sample with x = 0.01 as compared to 164 kJ/m³ for the x =0.05 composition. The value of Ed is comparable to other BaTiO₃ based lead free ferroelectric systems. Impedance spectroscopy analysis exhibited the bulk and grain boundary contributions above 300 °C under the frequency range 100 Hz to 1 MHz. The above properties make these ceramics suitable for energy storage devices.

Keywords: dielectric properties, energy storage properties, impedance spectroscopy, lead free ceramics

Procedia PDF Downloads 137

Authors: Vanessa Matias Leite, Jandira Guenka Palma, Flávio Henrique de Oliveira

Abstract:

This paper presents a model-oriented development approach to software development in the Model-View-Controller (MVC) architectural standard. This approach aims to expose a process of extractions of information from the models, in which through rules and syntax defined in this work, assists in the design of the initial model and its future conversions. The proposed paper presents a syntax based on the natural language, according to the rules agreed in the classic grammar of the Portuguese language, added to the rules of conversions generating models that follow the norms of the Object Management Group (OMG) and the Meta-Object Facility MOF.

Keywords: BNF Syntax, model driven architecture, model-view-controller, transformation, UML

Procedia PDF Downloads 376

Authors: H. Ben Khlifa, W. Cheikhrouhou, R. M'nassri

Abstract:

The Orthorhombic Pr0.8Na0.2MnO3 ceramic was prepared in Polycrystalline form by a Pechini sol–gel method and its structural, magnetic, electrical, and dielectric properties were investigated experimentally. A structural study confirms that the sample is a single phase. Magnetic measurements show that the sample is a charge ordered Manganite. The sample undergoes two successive magnetic phase transitions with the variation of temperature: a charge ordering transition occurred at TCO = 212 K followed by a Paramagnetic (PM) to ferromagnetic (FM) transition around TC = 115 K. From an electrical point of view, a saturation region was marked in the conductivity as a function of Temperature s(T) curves at a specific temperature. The dc-conductivity (sdc) reaches a maximum value at 240 K. The obtained results are in good agreement with the temperature dependence of the average normalized change (ANC). We found that the conduction mechanism was governed by small polaron hopping (SPH) in the high-temperature region and by variable range hopping (VRH) in the low-temperature region. Complex impedance analysis indicates the presence of a non-Debye relaxation phenomenon in the system. Also, the compound was modeled by an electrical equivalent circuit. Then, the contribution of the grain boundary in the transport properties was confirmed.

Keywords: manganites, preparation methods, magnetization, magnetocaloric effect, electrical and dielectric

Procedia PDF Downloads 148

Authors: Lina M. Vidal

Abstract:

This paper discusses yoga practices involvement in both self-transformation and social transformations by means of an embodied ethnographic approach to different initiatives for social change in Medellín. In the context of gradual popularization of embodied spiritualities, yoga practices have opened their way in calls for social change in a performative perspective which involves collective experiences, reflections and production of embodied knowledge. Through the reflection on bodily dimension and corporal experience, this ethnographic approach acknowledges inter-corporality and somatic modes of attention during observations and personal experiences. In social change initiatives that include yoga practices were identified transformations of common understanding on social issues such as it is produced by institutionalized education, health system and other fields of knowledge. This is clearly visible in yoga projects for children in vulnerable conditions, homeless people, prisoners, and young people recovering from drug addiction. These projects are often promoted by organizations and networks, which incorporate individual life stories into collective experiences. Dissemination of yoga is heading to a broad institutional and cultural legitimation of yoga and of spirituality that impact different fields of social work and everyday life in general. This way, yoga is becoming an embodied activist way of life and a legitimate field for social work.

Keywords: embodied ethnography, Medellin, social transformation, embodied spiritualities, yoga practices

Procedia PDF Downloads 168

Authors: Raksit Nanthatanti, Jarruwat Charoensuk, S. Hirai, Manop Masomtop

Abstract:

In this study, the effect of channel geometry and operating circumstances on a liquid cooling plate for Lithium-ion Battery modules has been investigated Inlet temperature, water velocity, and channel count were the main factors. According to the passage, enhancing the number of cooling channels[2,3,4,6channelperbases] will affect water flow distribution caused by varying the velocity inlet inside the cooling block[0.5,1.0,1.5,2.0 m/sec] and intake temperatures[25,30,35,40oC], The findings indicate that the battery’s temperature drops as the number of channels increases. The maximum battery's operating temperature [45 oC] rises, but ∆t is needed to be less than 5 oC [v≤1m/sec]. Maximum temperature and local temperature difference of the battery change significantly with the change of the velocity inlet in the cooling channel and its thermal conductivity. The results of the simulation will help to increase cooling efficiency on the cooling system for Li-ion Battery based on a Mini channel in a liquid-cooling configuration

Keywords: cooling efficiency, channel count, lithium-ion battery, operating

Procedia PDF Downloads 74

Authors: H. Higashiyama, M. Sano, F. Nakanishi, M. Sugiyama, M. Kawanishi, S. Tsukuma

Abstract:

The heat island phenomenon and extremely hot summer climate are becoming environmental problems in Japan. Cool pavements reduce the surface temperature compared to conventional asphalt pavements in the hot summer climate and improve the thermal environment in the urban area. The authors have studied cement–based grouting materials poured into voids in porous asphalt pavements to reduce the road surface temperature. For the cement–based grouting material, cement, ceramic waste powder, and natural zeolite were used. This cement–based grouting material developed reduced the road surface temperature by 20 °C or more in the hot summer season. Considering the urban landscape, this study investigates the effect of surface temperature reduction of colored cement–based grouting materials containing pigments poured into voids in porous asphalt pavements by measuring the surface temperature of asphalt pavements outdoors. The yellow color performed the same as the original cement–based grouting material containing no pigment and was thermally better performance than the other color. However, all the tested cement–based grouting materials performed well for reducing the surface temperature and for creating the urban landscape.

Keywords: ceramic waste powder, natural zeolite, road surface temperature, asphalt pavement, urban landscape

Procedia PDF Downloads 298

Authors: Bijay Kumar Sahoo

Abstract:

An important feature of InₓGa₁-ₓN/GaN heterostructures is strong built-in polarization (BIP) electric field at the hetero-interface due to spontaneous (sp) and piezoelectric (pz) polarizations. The intensity of this electric field reaches several MV/cm. This field has profound impact on optical, electrical and thermal properties. In this work, the effect of BIP field on thermal conductivity of InₓGa₁-ₓN/GaN heterostructure has been investigated theoretically. The interaction between the elastic strain and built in electric field induces additional electric polarization. This additional polarization contributes to the elastic constant of InₓGa₁-ₓN alloy. This in turn modifies material parameters of InₓGa₁-ₓN. The BIP mechanism enhances elastic constant, phonon velocity and Debye temperature and their bowing constants in InₓGa₁-ₓN alloy. These enhanced thermal parameters increase phonon mean free path which boost thermal conduction process. The thermal conductivity (k) of InxGa1-xN alloy has been estimated for x=0, 0.1, 0.3 and 0.9. Computation finds that irrespective of In content, the room temperature k of InₓGa₁-ₓN/GaN heterostructure is enhanced by BIP mechanism. Our analysis shows that at a certain temperature both k with and without BIP show crossover. Below this temperature k with BIP field is lower than k without BIP; however, above this temperature k with BIP field is significantly contributed by BIP mechanism leading to k with BIP field become higher than k without BIP field. The crossover temperature is primary pyroelectric transition temperature. The pyroelectric transition temperature of InₓGa₁-ₓN alloy has been predicted for different x. This signature of pyroelectric nature suggests that thermal conductivity can reveal pyroelectricity in InₓGa₁-ₓN alloy. The composition dependent room temperature k for x=0.1 and 0.3 are in line with prior experimental studies. The result can be used to minimize the self-heating effect in InₓGa₁-ₓN/GaN heterostructures.

Keywords: built-in polarization, phonon relaxation time, thermal properties of InₓGa₁-ₓN /GaN heterostructure, self-heating

Procedia PDF Downloads 388

Authors: M. Khazam, M. Altawil, A. Eljabri

Abstract:

Fluid properties in states near a vapor-liquid critical region are the most difficult to measure and to predict with EoS models. The principal model difficulty is that near-critical property variations do not follow the same mathematics as at conditions far away from the critical region. Libyan NC98 field in Sirte basin is a typical example of near critical fluid characterized by high initial condensate gas ratio (CGR) greater than 160 bbl/MMscf and maximum liquid drop-out of 25%. The objective of this paper is to model NC98 phase behavior with the proper selection of EoS parameters and also to model reservoir depletion versus gas cycling option using measured PVT data and EoS Models. The outcomes of our study revealed that, for accurate gas and condensate recovery forecast during depletion, the most important PVT data to match are the gas phase Z-factor and C7+ fraction as functions of pressure. Reasonable match, within -3% error, was achieved for ultimate condensate recovery at abandonment pressure of 1500 psia. The smooth transition from gas-condensate to volatile oil was fairly simulated by the tuned PR-EoS. The predicted GOC was approximately at 14,380 ftss. The optimum gas cycling scheme, in order to maximize condensate recovery, should not be performed at pressures less than 5700 psia. The contribution of condensate vaporization for such field is marginal, within 8% to 14%, compared to gas-gas miscible displacement. Therefore, it is always recommended, if gas recycle scheme to be considered for this field, to start it at the early stage of field development.

Keywords: EoS models, gas-condensate, gas cycling, near critical fluid

Procedia PDF Downloads 306

Authors: Eman A. Alghamdi, A. M. Aldhafiri

Abstract:

It was found that the induce an isolated dopant close to the middle of the bandgap by occupying the Cd position in the CdTe lattice structure is an efficient factor in reducing the nonradiative recombination rate and increasing the solar efficiency. According to our laboratory results, this work has been carried out to obtain the effect of substrate temperature on the CdTe0.6Sn0.4 prepared by thermal evaporation technique for photovoltaic application. Various substrate temperature (25°C, 100°C, 150°C, 200°C, 250°C and 300°C) was applied. Sn-doped CdTe thin films on a glass substrate at a different substrate temperature were made using CdTe and SnTe powders by the thermal evaporation technique. The structural properties of the prepared samples were determined using Raman, x-Ray Diffraction. Spectroscopic ellipsometry and spectrophotometric measurements were conducted to extract the optical constants as a function of substrate temperature. The structural properties of the grown films show hexagonal and cubic mixed structures and phase change has been reported. Scanning electron microscopy (SEM) reviled that a homogenous with a bigger grain size was obtained at 250°C substrate temperature. The conductivity measurements were recorded as a function of substrate temperatures. The open-circuit voltage was improved by controlling the substrate temperature due to the improvement of the fundamental material issues such as recombination and low carrier concentration. All the result was explained and discussed on the biases of the influences of the Sn dopant and the substrate temperature on the structural, optical and photovoltaic characteristics.

Keywords: CdTe, conductivity, photovoltaic, ellipsometry

Procedia PDF Downloads 107

Authors: Viney Dixit, Rohit R. Shahi, Ashish Bhatnagar, P. Jain, T. P. Yadav, O. N. Srivastava

Abstract:

Carbons are being widely investigated as hydrogen storage material owing to their light weight, fast hydrogen absorption kinetics and low cost. However, these materials suffer from low hydrogen storage capacity at room temperature. The aim of the present study is to synthesize carbon based material which shows moderate hydrogen storage at room temperature. For this purpose, hydrogenation characteristics of natural precursor coconut kernel is studied in this work. The hydrogen storage measurement reveals that the as-synthesized materials have good hydrogen adsorption and desorption capacity with fast kinetics. The synthesized material absorbs 8 wt.% of hydrogen at liquid nitrogen temperature and 2.3 wt.% at room temperature. This could be due to the presence of certain elements (KCl, Mg, Ca) which are confirmed by TEM.

Keywords: coconut kernel, carbonization, hydrogenation, KCl, Mg, Ca

Procedia PDF Downloads 401

Authors: Brody R. Clark, Chaminda Gallage, John Yeaman

Abstract:

Multigrade bitumen asphalt is a quality asphalt product that is not utilised in many places globally. Multigrade bitumen is believed to be less sensitive to temperature, which gives it an advantage over conventional binders. Previous testing has shown that asphalt temperature changes greatly with depth, but currently the industry standard is to nominate a single temperature for design. For detailed design of asphalt roads, perhaps asphalt layers should be divided into nominal layer depths and different modulus and fatigue equations/values should be used to reflect the temperatures of each respective layer. A collaboration of previous laboratory testing conducted on multigrade bitumen asphalt beams under a range of temperatures and loading conditions was analysed. The samples tested included 0% or 15% recycled asphalt pavement (RAP) to determine what impact the recycled material has on the fatigue life and stiffness of the pavement. This paper investigated the temperature susceptibility of multigrade bitumen asphalt pavements compared to conventional binders by combining previous testing that included conducting a sweep of fatigue tests, developing complex modulus master curves for each mix and a study on how pavement temperature changes through pavement depth. This investigation found that the final design of the pavement is greatly affected by the nominated pavement temperature and respective material properties. This paper has outlined a potential revision to the current design approach for asphalt pavements and proposes that further investigation is needed into pavement temperature and its incorporation into design.

Keywords: asphalt, complex modulus, fatigue life, flexural stiffness, four point bending, multigrade bitumen, recycled asphalt pavement

Procedia PDF Downloads 350

Authors: Yujiang Wu

Abstract:

As electrical machine (e-machine) power density re-querulents become more stringent in vehicle electrification, mounting a temperature sensor for e-machine stator windings becomes increasingly difficult. This can lead to higher manufacturing costs, complicated harnesses, and reduced reliability. In this paper, we propose a deep-learning method for predicting electric machine winding temperature, which can either replace the sensor entirely or serve as a backup to the existing sensor. We compare the performance of our method, the stateful long short-term memory networks (LSTM) with truncated backpropagation through time (TBTT), with that of linear regression, as well as stateless LSTM with/without residual connection. Our results demonstrate the strength of combining stateful LSTM and TBTT in tackling nonlinear time series prediction problems with long sequence lengths. Additionally, in industrial applications, high-temperature region prediction accuracy is more important because winding temperature sensing is typically used for derating machine power when the temperature is high. To evaluate the performance of our algorithm, we developed a temperature-stratified MSE. We propose a simple but effective data preprocessing trick to improve the high-temperature region prediction accuracy. Our experimental results demonstrate the effectiveness of our proposed method in accurately predicting winding temperature, particularly in high-temperature regions, while also reducing manufacturing costs and improving reliability.

Keywords: deep learning, electrical machine, functional safety, long short-term memory networks (LSTM), thermal management, time series prediction

Procedia PDF Downloads 80

Authors: Tommy Lo

Abstract:

This paper presented the changes in temperature and air ventilation of an inner urban area at different development stages during 2002 to 2012 and the high-rise buildings to be built in 2018. 3D simulation models ENVI-met and Autodesk Falcon were used. The results indicated that replacement of old residence buildings or open space with high-rise buildings will increase the air temperature of inner urban area; the air temperature at the pedestrian level will increase more than that at the upper levels. The temperature of the inner street in future will get higher than that in 2002, 2008 and 2012. It is attributed that heat is trapped in the street canyons as the air permeability at the pedestrian levels is lower. High-rise buildings with massive podium will further reduce the air ventilation in that area. In addition, sufficient separations among buildings is essential in design. High-rise buildings aligned along the waterfront will obstruct the wind flowing into the inner urban area and accelerate the temperature increase both in daytime and night time.

Keywords: micro-climate change, urban design, ENVI-met, construction engineering

Procedia PDF Downloads 267

Authors: Kamel Agroui, George Collins, Rydha Yaiche

Abstract:

The objective of this study is to better understand the thermal characteristics and molecular behaviour of cured EVA before and after outdoor exposure. Thermal analysis methods as DSC, TSC and DMTA studies were conducted on EVA material. DSC experiments on EVA show a glass transition at about -33.1° C which is characteristic of crystalline phase and an endothermic peak at temperature of 55 °C characteristic of amorphous phase. The magnitude of the integrated temperature DSC peak for EVA is 14.4 J/g. The basic results by TSC technique is that there are two relaxations that are reproducibly observed in cured EVA encapsulant material. At temperature polarization 85°C, a low temperature relaxation occurs at –24.4°C and a high temperature relaxation occurs at +30.4ºC. DMTA results exhibit two tan peaks located at -14.9°C and +66.6°C. After outdoor exposure cured EVA by DSC analysis revealed two endothermic peaks due to post crystallization phenomenon and TSC suggests that prolonged exposure selectively effects the poly(vinyl acetate)-rich phase, with much less impact on the polyethylene-rich phase.

Keywords: EVA, encapsulation process, PV module, thermal analysis, quality control

Procedia PDF Downloads 31

Authors: Kyoung Hoon Kim

Abstract:

The absorption power generation cycle based on the ammonia-water mixture has attracted much attention for efficient recovery of low-grade energy sources. In this paper, a thermodynamic performance analysis is carried out for a Kalina cycle using ammonia-water mixture as a working fluid for efficient conversion of low-temperature heat source in the form of sensible energy. The effects of the source temperature on the system performance are extensively investigated by using the thermodynamic models. The results show that the source temperature as well as the ammonia mass fraction affects greatly on the thermodynamic performance of the cycle.

Keywords: ammonia-water mixture, Kalina cycle, low-grade heat source, source temperature

Procedia PDF Downloads 443

Authors: Kyungbong Kim

Abstract:

This study proposed to compare and analyse the five stages of cultivating the Yogâcāra path and the spiritual journey in the Ten Ox-Herding Pictures. To achieve this, the study investigated the core concepts and practice methods of the two approaches and analysed their relations from the literature reviewed. The results showed that the end goal of the two approaches is the same, the attainment of Buddhahood, with the two having common characteristics including the practice of being aware of the impermanent and non-self, and the fulfilling benefit of sentient beings. The results suggest that our Buddhist practice system needs to sincerely consider the realistic ways by which one can help people in agony in contemporary society, not by emphasizing on the enlightenment through a specific practice way for all people, but by tailored practice methods based on each one's faculties in understanding Buddhism.

Keywords: transformation of consciousness to wisdom, enlightenment, the five stages of cultivating the Yogacāra path, the Ten Ox-Herding Pictures, transformation of the basis

Procedia PDF Downloads 250