Search results for: temperature change

Authors: Abdellatif Chebboub

Abstract:

Agricultural production is sensitive to weather and thus directly affected by climate change. Plausible estimates of these climate change impacts require combined use of climate, crop, and economic models. Results from previous studies vary substantially due to differences in models, scenarios, and data. This paper is part of a collective effort to systematically integrate these three types of models. We focus on the economic component of the assessment, investigating how nine global economic models of agriculture represent endogenous responses to seven standardized climate change scenarios produced by two climate and five crop models. These responses include adjustments in yields, area, consumption, and international trade. We apply biophysical shocks derived from the Intergovernmental Panel on Climate Change’s representative concentration pathway with end-of-century radiative forcing of 8.5 W/m2. The mean biophysical yield effect with no incremental CO2 fertilization is a 17% reduction globally by 2050 relative to a scenario with unchanging climate. Endogenous economic responses reduce yield loss to 11%, increase area of major crops by 11%, and reduce consumption by 3%. Agricultural production, cropland area, trade, and prices show the greatest degree of variability in response to climate change, and consumption the lowest. The sources of these differences include model structure and specification; in particular, model assumptions about ease of land use conversion, intensification, and trade. This study identifies where models disagree on the relative responses to climate shocks and highlights research activities needed to improve the representation of agricultural adaptation responses to climate change.

Keywords: climate change, agriculture, weather change, danger of climate change

Procedia PDF Downloads 316

Authors: Geng Xiangren, Liu Lei, Gui Ye-Wei, Tang Wei, Wang An-ling

Abstract:

The malfunction of thermal protection system (TPS) caused by aerodynamic heating is a latent trouble to aircraft structure safety. Accurately predicting the structure temperature field is quite important for the TPS design of hypersonic vehicle. Since Thornton’s work in 1988, the coupled method of aerodynamic heating and heat transfer has developed rapidly. However, little attention has been paid to the influence of structural deformation on aerodynamic heating and structural temperature field. In the flight, especially the long-endurance flight, the structural deformation, caused by the aerodynamic heating and temperature rise, has a direct impact on the aerodynamic heating and structural temperature field. Thus, the coupled interaction cannot be neglected. In this paper, based on the method of static aero-thermo-elasticity, considering the influence of aero-thermo-elasticity deformation, the aerodynamic heating and heat transfer coupled results of hypersonic vehicle wing model were calculated. The results show that, for the low-curvature region, such as fuselage or center-section wing, structure deformation has little effect on temperature field. However, for the stagnation region with high curvature, the coupled effect is not negligible. Thus, it is quite important for the structure temperature prediction to take into account the effect of elastic deformation. This work has laid a solid foundation for improving the prediction accuracy of the temperature distribution of aircraft structures and the evaluation capacity of structural performance.

Keywords: aerothermoelasticity, elastic deformation, structural temperature, multi-field coupling

Procedia PDF Downloads 341

Authors: Xiaoxin Ye, Guoyi Tang

Abstract:

The effect of electropulsing ultrasonic shock (EUS) on the surface hardening and microstructure of Ti6Al4V alloy was studied. It was found that electropulsing improved the microhardness dramatically both in the influential depth and maximum value, compared with the only ultrasonic-shocked sample. It’s indicated that refined surface layer with nanocrystalline and improved microhardness were obtained on account of surface severe plastic deformation, dynamic recrystallization (DRX) and phase change, which was implemented at relative low temperature and high strain rate/capacity due to the coupling of the thermal and athermal effects of EUS. It’s different from conventional experiments and theory. It’s discussed that the positive contributions of EPT in the thermodynamics and kinetics of microstructure and properties change were attributed to the reduction of nucleation energy barrier and acceleration of atomic diffusion. Therefore, it’s supposed that EUS is an energy-saving and high-efficiency method of surface treatment technique with the help of high-energy electropulses, which is promising in cost reduction of the surface engineering and energy management.

Keywords: titanium alloys, electropulsing, ultrasonic shock, microhardness, nanocrystalline

Procedia PDF Downloads 291

Authors: Orose Rugchati, Kanita Thanacharoenchanaphas, Sarawut Wattanawongpitak

Abstract:

In this study, the effect of electric stimulation on the quality of hot-boned beef brisket muscles was evaluated, including the tenderness, pH, temperature change, and colorant. Muscles were obtained from steers in the local slaughter house. (3 steers for each muscle), removed from the carcasses 4-hour postmortem and variable time to treated with direct current electric 1 and 5 minutes, respectively. Six different electric intensities (direct current voltage of 50, 70 and 90 Volt, pulse with 10, 20 and 40 ms) plus a control were applied to each muscle to determine the optimum treatment conditions. Hot-boned beef brisket was found to get tender with increasing treatment direct current voltage and reduction in the shear force with pulsed with electric treatment. But in a long time to treated with electric current get fading in red color and temperature increase whereas pH quite different compared to non-treated control samples.

Keywords: electric stimulation, characteristic changes, hot-boned beef brisket, potential tenderness

Procedia PDF Downloads 342

Authors: Rasikh Tariq, Fatima Z. Benarab

Abstract:

Evaporative coolers has a minimum potential to reach the wet-bulb temperature of intake air which is not enough to handle a large cooling load; therefore, it is not a feasible option to overcome cooling requirement of a building. The invention of Maisotsenko (M) cycle has led evaporative cooling technology to reach the sub-wet-bulb temperature of the intake air; therefore, it brings an innovation in evaporative cooling techniques. In this work, we developed a mathematical model of the Maisotsenko based air cooler by applying energy and mass balance laws on different air channels. The governing ordinary differential equations are discretized and simulated on MATLAB. The temperature and the humidity plots are shown in the simulation results. A parametric study is conducted by varying working air inlet conditions (temperature and humidity), inlet air velocity, geometric parameters and water temperature. The influence of these aforementioned parameters on the cooling effectiveness of the HMX is reported.  Results have shown that the effectiveness of the M-Cycle is increased by increasing the ambient temperature and decreasing absolute humidity. An air velocity of 0.5 m/sec and a channel height of 6-8mm is recommended.

Keywords: HMX, maisotsenko cycle, mathematical modeling, numerical simulation, parametric study

Procedia PDF Downloads 147

Authors: Akachi Odoemene

Abstract:

Climate change and land grabbing are tightly interconnected in ways that are both diverse and complex. They have impacted each other in significant ways too. Both phenomena are not only a political reality, but have diverse dire implications, especially for food and livelihood security of vulnerable populations in developing economies. The critical nexus and interactions of climate change and land grabbing remain one of the challenges of sustainable development in modern times. The nuanced understanding of the nexus, importance and implications of climate change and land grabbing are the primary focus of this chapter. It begins with conceptual clarifications, particularly arguing that the absence of some important principles of engagement underline and define a land grab. It also analyses and notes a good number of contemporary land deals as 'one-sided', in which wealthy entities connive with local elites to exploit and disposes rural poor populations. The paper not only examines both global and local factors that drive land grabbing and, in some cases, their connections with the incidence of climate change, but also explores their crucial links with such sector as agriculture. It is argued and exhibited in the paper why certain societies are susceptible to the incidence of climate change and land grabbing, while the overall consequences of these phenomena on the affected societies are further interrogated. The paper concludes that the lack of political will by global political leaders to effectively combat and resolve critical issues associated with both climate change and land grabbing remains a daunting challenge. It notes that these phenomena – climate change and land grabbing – if not abated, will certainly become another set of global tragic episodes to be regretted in the future.

Keywords: climate change, land grabbing, global governance, developing economies

Procedia PDF Downloads 292

Authors: Xiaojie Cheng, Ulrike Frank, Feng Zhao, Karin Pritsch

Abstract:

Ragweed (Ambrosia artemisiifolia) is an invasive weed that has become an increasing global problem. In addition to affecting land use and crop yields, ragweed has a strong impact on human health as it produces highly allergenic pollen. Global warming will result in an earlier and longer pollen season enhanced pollen production and an increase in pollen allergenicity with a negative effect on atopic patients. The aims of this study were to investigate the effects of increasing temperature, the future climate scenario in the Munich area, southern Germany, predicted on the basis of RCP8.5 until the end of 2050s, or/and NO₂, a major air pollutant, 1) on the vegetative and reproductive characteristics of ragweed plants, 2) on the total allergenicity of ragweed pollen, 3) on the total pollen proteomic patterns. Ragweed plants were cultivated for the whole plant vegetation period under controlled conditions either under ambient climate conditions or 4°C higher temperatures with or without additional NO₂. Higher temperature resulted in bigger plant sizes, longer male inflorescences, and longer pollen seasons. The total allergenic potential of the pollen was accessed by dot blot using serum from ragweed pollen sensitized patients. The comparative immunoblot analysis revealed that the in vivo fumigation of ragweed plants with elevated NO₂-concentrations significantly increased the allergenic potential of the pollen, and in combination with increased temperature, the allergenic potential was even higher. On the other hand, label-free protein quantification by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was performed. The results showed that more proteins were significantly up- and down-regulated under higher temperatures with/without elevated NO₂ conditions. Most of the highly expressed proteins were participating intensively in the metabolic process, the cellular process, and the stress defense process. These findings suggest that rising temperature and elevated NO₂ are important environmental factors for higher abiotic stress activities, catalytic activities, and thus higher allergenic potential observed in pollen proteins.

Keywords: climate change, NO₂, pollen proteome, ragweed, temperature

Procedia PDF Downloads 191

Authors: Anuschka Curran, Sandra Barnard

Abstract:

Coral reefs are of the most diverse and productive ecosystems on the planet, but due to the impact of climate change, these infrastructures are dying off primarily through coral bleaching. Coral bleaching can be described as the process by which zooxanthellae (algal endosymbionts) are expelled from the gastrodermal cavity of the respective coral host, causing increased coral whitening. The general consensus is that mass coral bleaching is due to the dysfunction of photosynthetic processes in the zooxanthellae as a result of the combined action of elevated temperature and light-stress. The question then is, do zooxanthellae have the potential to play a key role in the future of coral reef restoration through genetic engineering? The aim of this study is firstly to review the different zooxanthellae taxa and their traits with respect to environmental stress, and secondly, to review the information available on the protective mechanisms present in zooxanthellae cells when experiencing temperature fluctuations, specifically concentrating on heat shock proteins and the antioxidant stress response of zooxanthellae. The eight clades (A-H) previously recognized were redefined into seven genera. Different zooxanthellae taxa exhibit different traits, such as their photosynthetic stress responses to light and temperature. Zooxanthellae have the ability to determine the amount and type of heat shock proteins (hsps) present during a heat response. The zooxanthellae can regulate both the host’s respective hsps as well as their own. Hsps, generally found in genotype C3 zooxanthellae, such as Hsp70 and Hsp90, contribute to the thermal stress response of the respective coral host. Antioxidant activity found both within exposed coral tissue, and the zooxanthellae cells can prevent coral hosts from expelling their endosymbionts. The up-regulation of gene expression, which may mitigate thermal stress induction of any of the physiological aspects discussed, can ensure stable coral-zooxanthellae symbiosis in the future. It presents a viable alternative strategy to preserve reefs amidst climate change. In conclusion, despite their unusual molecular design, genetic engineering poses as a useful tool in understanding and manipulating variables and systems within zooxanthellae and therefore presents a solution that can ensure stable coral-zooxanthellae symbiosis in the future.

Keywords: antioxidant enzymes, genetic engineering, heat-shock proteins, Symbiodinium

Procedia PDF Downloads 189

Authors: Amira Zrelli, Tahar Ezzeddine

Abstract:

Measurement and monitoring of temperature, humidity and strain variation are very requested in great fields and areas such as structural health monitoring (SHM) systems. Currently, the use of fiber Bragg grating sensors (FBGS) is very recommended in SHM systems due to the specifications of these sensors. In this paper, we present the theory of Bragg sensor, therefore we try to measure the efficient variation of strain, temperature and humidity (SV, ST, SH) using Bragg sensor. Thus, we can deduce the fundamental relation between these parameters and the wavelength of Bragg sensor.

Keywords: Fiber Bragg Grating Sensors (FBGS), strain, temperature, humidity, structural health monitoring (SHM)

Procedia PDF Downloads 315

Authors: Mario Belseran

Abstract:

The issue of climate change become world attention where one of them increase in air temperature due to greenhouse gas emissions. This climate change is caused by gases in the atmosphere, one of which is CO2. DKI Jakarta as the capital has a dense population with a variety of existing land use. Land use that is dominated by settlements resulting in fewer green space, which functions to absorb atmospheric CO2. Image interpretation SPOT-7 is used to determine the greenness level of vegetation on a green space using the vegetation index NDVI, EVI, GNDVI and OSAVI. Measuring the diameter and height of trees were also performed to obtain the value of biomass that will be used as the CO2 absorption value. The CO2 absorption value that spread in Jakarta are classified into three classes: high, medium, and low. The distribution pattern of CO2 absorption value at green space in Jakarta dominance in the medium class with the distribution pattern is located in South Jakarta, East Jakarta, North Jakarta and West Jakarta. The distribution pattern of green space in Jakarta scattered randomly and more dominate in East Jakarta and South Jakarta

Keywords: carbon dioxide, DKI Jakarta, green space, SPOT-7, vegetation index

Procedia PDF Downloads 280

Authors: K. L. Kabemba, R. F. Sandenberg

Abstract:

The usual way to desorb gold is by elution with a hot concentrated alkaline solution of sodium cyanide. The high temperature is necessary because the dielectric constant of water decreases with increasing temperature hence the electrostatic forces between charcoal and the gold cyanide complex decreases. High alkalinity and a high concentration of cyanide are necessary for gold desorption because both OH- and CN- ions are preferentially adsorbed. The rate of elution increases with increasing anion concentration but decreases with increasing cation concentration that means the rate of elution passes through a maximum as the concentration of the eluting salt (NaCN, for example) is increased. The anion that gives the best results, the cyanide ion, decomposes fairly rapidly at elevated temperatures (40% in 6 hours, 90% in 24 hours at 95°C).

Keywords: caustic, cyanide, gold, temperature

Procedia PDF Downloads 387

Authors: Chargui Ridha, Agrebi Sameh

Abstract:

The integration of phase change materials (PCM) for the storage of thermal energy during the period of sunshine before being released during the night is a complement of free energy to improve the system formed by a solar collector, tank storage, and a heat exchanger. This paper is dedicated to the design of a thermal storage tank based on a PCM-based heat exchanger. The work is divided into two parts: an experimental part using paraffin as PCM was carried out within the Laboratory of Thermal Processes of Borj Cedria in order to improve the performance of the system formed by the coupling of a flat solar collector and a thermal storage tank and to subsequently determine the influence of PCM on the whole system. This phase is based on the measurement instrumentation, namely, a differential scanning calorimeter (DSC) and the thermal analyzer (hot disk: HOT DISK) in order to determine the physical properties of the paraffin (PCM), which has been chosen. The second phase involves the detailed design of the PCM heat exchanger, which is incorporated into a thermal storage tank and coupled with a solar air collector installed at the Research and Technology Centre of Energy (CRTEn). A numerical part based on the TRANSYS and Fluent software, as well as the finite volume method, was carried out for the storage reservoir systems in order to determine the temperature distribution in each chosen system.

Keywords: phase change materials, storage tank, heat exchanger, flat plate collector

Procedia PDF Downloads 94

Authors: Ravinder Dachepalli, Naveena Gadwala, K. Vani

Abstract:

Nd and Er substituted bismuth nano crystalline multifunctional materials were prepared by citrate gel autocombution technique. The structural characterization was carried out by XRD and SEM. Electrical properties such are electrical conductivity and dielectric properties have been measured. Plots of electrical conductivity versus temperature increases with increasing temperature and shown a transition near Curie temperature. Dielectric properties such are dielectric constant and dielectric loss tangent have been measured from 20Hz to 2 MHz at room temperature. Plots of dielectric constant versus frequency show a normal dielectric behaviour of multifunctional materials. Temperature dependence of magnetic properties of Bi-Nd and Bi-Er multi-functional materials were carried out by using Vibrating sample magnetometer (VSM). The magnetization as a function of an applied field ±100 Oe was carried out at 3K and 360 K. Zero field Cooled (ZFC) and Field Cooled (FC) magnetization measurements under an applied field of 100Oe a in the temperature range of 5-375K. The observed results can be explained for spintronic devices.

Keywords: Bi-Nd and Bi-Er Multifunctional Materia, Citrate Gel Auto combustion Technique, FC-ZFC magnetization, Dielectric constant

Procedia PDF Downloads 400

Authors: Mara Balestrieri

Abstract:

Climate change has long been the focus of attention for the growing impact of extreme weather events and global warming in many areas of the planet and the evidence of economic, social, and environmental damage caused by global warming. Nowadays, climate change is recognized as a critical global problem. Several initiatives have been undertaken over time to enhance the long theoretical debate and field experience in order to reduce Co2 emissions and contain climate alteration. However, the awareness that climate change is already taking place has led to a growing demand for adaptation. It is certainly a matter of anticipating the negative effects of climate change but, at the same time, implementing appropriate actions to prevent climate change-related damage, minimize the problems that may result, and also seize any opportunities that may arise. Consequently, adaptation has become a core element of climate policy and research. However, the attention to this issue has not developed in a uniform manner across countries. Some countries are further ahead than others. This paper examines the literature on climate change adaptation developed until 2018 in Italy, considering the urban dimension, to provide a framework for it, and to identify main topics and features. The papers were selected from Scopus and were analyzed through a matrix that we propose. Results demonstrate that adaptation to climate change studies attracted increasing attention from Italian scientific communities in the last years, although Italian scientific production is still quantitatively lower than in other countries and describes strengths and weaknesses in line with international panorama with respect to objectives, sectors, and problems.

Keywords: adaptation, bibliometric literature, climate change, urban studies

Procedia PDF Downloads 74

Authors: Ahmed Elsebaay, Maged A. Abu Adma, Mahmoud Ramadan

Abstract:

This study presents a technique clarifying the effect of ambient air temperature and loads power factor changing from standard values on electric generator power rating. The study introduces an optimized technique for selecting the correct electric generator power rating for certain application and operating site ambient temperature. The de-rating factors due to the previous effects will be calculated to be applied on a generator to select its power rating accurately to avoid unsafe operation and save its lifetime. The information in this paper provides a simple, accurate, and general method for synchronous generator selection and eliminates common errors.

Keywords: ambient temperature, de-rating factor, electric generator, power factor

Procedia PDF Downloads 358

Authors: Vidhya Venugopal, Jeremiah Chinnadurai, Rebekah A. I. Lucas, Tord Kjellstrom, Bruno Lemke

Abstract:

Introduction: The effects of climate change (CC) are largely discussed across the globe in terms of impacts on the environment and the general population, but the impacts on workers remain largely unexplored. The predicted rise in temperatures and heat events in the CC scenario have health implications on millions of workers in physically exerting jobs. The current health and productivity risks associated with heat exposures are characterized, future risk estimates as temperature rises and recommendations towards developing protective and preventive occupational health and safety guidelines for India are discussed. Methodology: Cross-sectional studies were conducted in several occupational sectors with workers engaged in moderate to heavy labor (n=1580). Quantitative data on heat exposures (WBGT°C), physiological heat strain indicators viz., Core temperature (CBT), Urine specific gravity (USG), Sweat rate (SwR) and qualitative data on heat-related health symptoms and productivity losses were collected. Data were analyzed for associations between heat exposures, health and productivity outcomes related to heat stress. Findings: Heat conditions exceeded the Threshold Limit Value (TLV) for safe manual work in 66% of the workers across several sectors (Avg.WBGT of 28.7°C±3.1°C). Widespread concerns about heat-related health outcomes (86%) were prevalent among workers exposed to high TLVs, with excessive sweating, fatigue and tiredness being commonly reported by workers. The heat stress indicators, core temperature (14%), Sweat rate (8%) and USG (9%), were above normal levels in the study population. A significant association was found between rise in Core Temperatures and WBGT exposures (p=0.000179) Elevated USG and SwR in the worker population indicate moderate dehydration, with potential risks of developing heat-related illnesses. In a steel industry with high heat exposures, an alarming 9% prevalence of kidney/urogenital anomalies was observed in a young workforce. Heat exposures above TLVs were associated with significantly increased odds of various adverse health outcomes (OR=2.43, 95% CI 1.88 to 3.13, p-value = <0.0001) and productivity losses (OR=1.79, 95% CI 1.32 to 2.4, p-value = 0.0002). Rough estimates for the number of workers who would be subjected to higher than TLV levels in the various RCP scenarios are RCP2.6 =79%, RCP4.5 & RCP6 = 81% and at RCP 8.5 = 85%. Rising temperatures due to CC has the capacity to further reduce already compromised health and productivity by subjecting the workers to increased heat exposures in the RCP scenarios are of concern for the country’s occupational health and economy. Conclusion: The findings of this study clearly identify that health protection from hot weather will become increasingly necessary in the Indian subcontinent and understanding the various adaptation techniques needs urgent attention. Further research with a multi-targeted approach to develop strategies for implementing interventions to protect the millions of workers is imperative. Approaches to include health aspects of climate change within sectoral and climate change specific policies should be encouraged, via a number of mechanisms, such as the “Health in All Policies” approach to avert adverse health and productivity consequences as climate change proceeds.

Keywords: heat stress, occupational health, productivity loss, heat strain, adverse health outcomes

Procedia PDF Downloads 323

Authors: Malek Jamaliah, Robert Powell

Abstract:

In spite of the influence of climate change on tourism destinations, particularly those rely heavily on natural resources, little attention paid to study the appropriate adaptation efforts to cope with, moderate and benefit from the impacts of climate change. The existing literature indicated that the research of climate change adaptation in the tourism and outdoor recreation field is at least 5-7 years behind other sectors such as water resources and agriculture. In Jordan, there are many observed changes in climate patterns such as higher temperatures, decreased precipitation and increased severity and frequency of drought. Dana Biosphere Reserve (DBR), the largest protected area and the major eco-tourism destination in Jordan, is facing climate change, which gradually degrading environment, shifting tourism seasons and changing livelihood and lifestyle of local communities. This study aims to assess climate change adaptation practices and policies used in DBR to cope with climate change related-risks. We conducted qualitative semi-structured interviews with key informants in DBR to assess climate change adaptation practices. Direct content analysis (or a priori content analysis) was used to determine the components and indicators of climate change adaptation. The results found that DBR has implemented a wide range of adaptation practices, including infrastructure development, diversification of tourism products, environmentally-friendly practices, visitor management, land use management, rainwater collection, environmental monitoring and research, environmental education and collaboration with stakeholders. These diverse practices implicitly and explicitly play an important role in coping with the social, economic and environmental impacts caused by climate change. Finally, this study demonstrated that climate change adaptation is closely related to sustainable management of eco-tourism.

Keywords: climate change adaptation, dana biosphere reserve, ecotourism, sustainable management

Procedia PDF Downloads 511

Authors: Ivar Zekker, Ergo Rikmann, Anni Mandel, Markus Raudkivi, Kristel Kroon, Liis Loorits, Andrus Seiman, Hannu Fritze, Priit Vabamäe, Toomas Tenno, Taavo Tenno

Abstract:

The anaerobic ammonium oxidation (anammox) and nitritation-anammox (deammonification) processes are widely used for N-rich wastewater treatment nowadays. A deammonification moving bed biofilm reactor (MBBR) with a high maximum total nitrogen removal rate (TNRR) of 1.5 g N m-2 d-1 was started up and similarly high TNRR was sustained at low temperature of 15°C. During biofilm cultivation, temperature in MBBR was lowered by 0.5° C week-1 sustaining the high TNRR. To study the short-term effect of temperature on the TNRR, a series of batch-scale experiments performed showed sufficient TNRRs even at 9-15° C (4.3-5.4 mg N L-1 h-1, respectively). After biomass was adapted to lower temperature (15°C), the TNRR increase at lower temperature (15°C) was relatively higher (15-20%) than with biomass adapted to higher temperatures (17-18°C). Anammox qPCR showed increase of Candidatus Brocadia quantities from 5×103 to 1×107 anammox gene copies g-1 TSS despite temperature lowered to 15°C. Modeling confirmed causes of stable and unstable periods in the reactor and in batch test high Arrhenius constant of 29.7 kJ mol-1 of the process as high as at 100 mg NO2--N L-1 were determined. 

Keywords: deammonification, reject water, intermittent aeration, nitrite inhibition

Procedia PDF Downloads 417

Authors: Nour El Houda Arabi, Aicha Iratni, Talaighil Razika, Bruno Capoen, Mohamed Bouazaoui

Abstract:

In this paper, we report the effect of the calcination temperature and SiO2 addition on structural, optical and hydrophilicity of TiO2 films deposited by deep-coating sol-gel process. XRD investigation of the structural TiO2 films with increasing the temperature calcination, reveals that rutile phase will appear for the high temperature (>1000°C). However, the addition of SiO2 relate the densification of TiO2 films. Ellipsometric and UV-visible measure show that the refractive index grow with increasing temperature, against the film thickness decreases. On the other hand, the addition of SiO2 decreases the refractive index and increases the TiO2 film thickness. Finally, the hydrophilicity is assisted by contact angle measurement. It is found that addition of 50% of SiO2 to TiO2 is most effective for reducing the contact angle of water.

Keywords: physical properties, sol, gel, TiO2/SiO2 composite films

Procedia PDF Downloads 493

Authors: Fatemeh Alsadat Miri, Morteza Ehsani, Hossein Ali Khonakdar, Behjat Kavyani

Abstract:

This paper studies the effect of nano glass flakes on morphology, dynamic-mechanical properties, and crystallization behavior of poly (ethylene terephthalate) (PET). The concentration of nano glass flakes was varied from 0.5, 1, 2, and 3% wt of the total formulation. Scanning electron microscopy (SEM) micrographs showed the poor distribution of nano-glass flake particles in PET, as well as low adhesion of particles to the polymer matrix. According to differential scanning calorimetry (DSC), the crystallization rate and crystallization temperature of PET were increased by the addition of nano glass flakes. The crystallization rate of PET was increased from 31.41% to 34.25% by the incorporation of 1%wt of nano glass flakes. Based on the results of the dynamic-mechanical analysis, the storage modulus of PET gets increased by adding nano glass flakes, especially below glass transition temperature (Tg). The glass transition of PET did not change remarkably with the addition of nano glass flakes. Moreover, the use of nano glass flakes reduced the impact strength of PET.

Keywords: PET, nano glass flakes, morphology, crystallization

Procedia PDF Downloads 127

Authors: Anna Bykalyuk, Frédéric Kuznik, Kévyn Johannes

Abstract:

In this paper, the influence of a vertical plate’s thermal capacity is numerically investigated in order to evaluate the evolution of the thermal boundary layer structure, as well as the convective heat transfer coefficient and the velocity and temperature profiles. Whereas the heat flux of the heated vertical plate is evaluated under time depending boundary conditions. The main important feature of this problem is the unsteadiness of the physical phenomena. A 2D CFD model is developed with the Ansys Fluent 14.0 environment and is validated using unsteady data obtained for plasterboard studied under a dynamic temperature evolution. All the phenomena produced in the vicinity of the thermal conductive vertical plate (plasterboard) are analyzed and discussed. This work is the first stage of a holistic research on transient free convection that aims, in the future, to study the natural convection in the vicinity of a vertical plate containing Phase Change Materials (PCM).

Keywords: CFD modeling, natural convection, thermal conductive plate, time-depending boundary conditions

Procedia PDF Downloads 277

Authors: Jung-Ho Moon, Tae Kwon Ha

Abstract:

Abstract—High temperature deformation behavior of cast Fe-20Cr-5Al alloy has been investigated in this study by performing tensile and compression tests at temperatures from 1100 to 1200oC. Rectangular ingots of which the dimensions were 300×300×100 in millimeter were cast using vacuum induction melting. Phase equilibrium was calculated using the FactSage®, thermodynamic software and database. Tensile strength of cast Fe-20Cr-5Al alloy was 4 MPa at 1200oC. With temperature decreased, tensile strength increased rapidly and reached up to 13 MPa at 1100oC. Elongation also increased from 18 to 80% with temperature decreased from 1200oC to 1100oC. Microstructure observation revealed that M23C6 carbide was precipitated along the grain boundary and within the matrix.

Keywords: 20 Cr-5Al ferritic stainless, high temperature deformation, aging treatment, microstructure, mechanical properties

Procedia PDF Downloads 449

Authors: Dêivisson Alves Anjos, Blenda Fonseca Aires Teles, Queitiane Castro Costa

Abstract:

Fire is one of the biggest dangers for factories, warehouses, mills, among other places, causing unimaginable damage, because besides the material damage also directly affects the lives of workers who are likely to suffer death or very serious consequences. This protection of the lives of these people should be taken seriously, always seeking safety. Thus investment in security and monitoring equipment must be high, so you can prevent or reduce the impacts of a possible fire. Our device, made in PIC micro controller monitors the temperature and the presence of gas in the environment, it sends the data via Bluetooth device to a developed in LabVIEW interface saves these data continuously and alert if the temperature exceeds the allowed or some gas is detected. Currently the device is in operation and can perform several tests, as well as use in different areas for which you need anti-fire protection.

Keywords: pic, bluetooth, fire, temperature, gas, LabVIEW

Procedia PDF Downloads 532

Authors: Nadia Theuma

Abstract:

Climate change is a reality that has started to leave an impact on the physical environment as well as on the built environment, in particular built heritage. This paper explores the argument that climate change is also a trigger which can lead to identifying a number of creative solutions that can transform built heritage into sustainable buildings. Using the Maltese Islands, and in particular the city of Valletta which is also a World Heritage Site, this paper illustrates some of the innovative solutions that are being developed to make heritage buildings more sustainable and in doing so, mitigating the negative impacts of climate change. The paper looks in detail at the most notable initiatives being developed, their implementation and application, which at times is not easy considering the restrictions within protected built heritage areas and the positive impacts that they will have on visitor experience and overall sustainability of the Maltese tourism product. The paper will conclude by outlining how these solutions can be adapted to buildings with similar climatic conditions.

Keywords: built heritage, creative solutions, climate change, Maltese Islands

Procedia PDF Downloads 290

Authors: Hamed Reza Heshmat Mohajer, Lan Ding, Mattheos Santamouris

Abstract:

One of the worst environmental dangers for people who live in cities is the Urban Heat Island (UHI) impact which is anticipated to become stronger in the coming years as a result of climate change. Accordingly, the key aim of this paper is to study the interaction between the urban configuration and mitigation strategies including increasing albedo of the urban environment (reflective material), implementation of Urban Green Infrastructure (UGI) and/or a combination thereof. To analyse the microclimate models of different urban categories in the metropolis of Sydney, this study will assess meteorological parameters using a 3D model simulation tool of computational fluid dynamics (CFD) named ENVI-met. In this study, four main parameters are taken into consideration while assessing the effectiveness of UHI mitigation strategies: ambient air temperature, wind speed/direction, and outdoor thermal comfort. Layouts with present condition simulation studies from the basic model (scenario one) are taken as the benchmark. A base model is used to calculate the relative percentage variations between each scenario. The findings showed that maximum cooling potential across different urban layouts can be decreased by 2.15 °C degrees by combining high-albedo material with flora; besides layouts with open arrangements(OT1) present a highly remarkable improvement in ambient air temperature and outdoor thermal comfort when mitigation technologies applied compare to compact counterparts. Besides all layouts present a higher intensity on the maximum ambient air temperature reduction rather than the minimum ambient air temperature. On the other hand, Scenarios associated with an increase in greeneries are anticipated to have a slight cooling effect, especially on high-rise layouts.

Keywords: sustainable urban development, urban green infrastructure, high-albedo materials, heat island effect

Procedia PDF Downloads 94

Authors: Karim Kheloufi, El Hachemi Amara

Abstract:

In the present study, a three-dimensional transient numerical model was developed to study the temperature field and cutting kerf shape during laser fusion cutting. The finite volume model has been constructed, based on the Navier–Stokes equations and energy conservation equation for the description of momentum and heat transport phenomena, and the Volume of Fluid (VOF) method for free surface tracking. The Fresnel absorption model is used to handle the absorption of the incident wave by the surface of the liquid metal and the enthalpy-porosity technique is employed to account for the latent heat during melting and solidification of the material. To model the physical phenomena occurring at the liquid film/gas interface, including momentum/heat transfer, a new approach is proposed which consists of treating friction force, pressure force applied by the gas jet and the heat absorbed by the cutting front surface as source terms incorporated into the governing equations. All these physics are coupled and solved simultaneously in Fluent CFD®. The main objective of using a transient phase change model in the current case is to simulate the dynamics and geometry of a growing laser-cutting generated kerf until it becomes fully developed. The model is used to investigate the effect of some process parameters on temperature fields and the formed kerf geometry.

Keywords: laser cutting, numerical simulation, heat transfer, fluid flow

Procedia PDF Downloads 339

Authors: Muqaddas Butt, Allah Bakhsh Malik

Abstract:

The changing educational environment, the diverse educational needs of students, the high expectations from the public, and the policy reports demand a strong change & innovation in the curriculum. Effective change and innovation could not be possible without the involvement of two major tenants i.e. teachers and educational managers. Thus, the locus of this research was to explore the secondary school principals and teachers priorities regarding change and innovation in curriculum. The main research objectives were included to explore the secondary school teachers’ and principals’ views about existing Humanities group curriculum; to identify their priorities regarding change and innovation in curriculum and to make a comparison between the priorities of both (the teachers & principals). A total sample of 150 Secondary school teachers and 24 principals from Federal Government Secondary Schools was drawn. The data was obtained through a five point Likert scale questionnaire. The findings indicated a huge difference between principals and teachers priorities. Related to prevailed curriculum, teachers showed more satisfactory views than principals. It was also found that the principals in comparison with teachers showed more inclination towards change and innovation and emphasized on an interdisciplinary, practical and ICT Integrated curriculum. Inclusion of local environmental issues; creativity based and practical activities based curriculum; and orientation to citizenship education into curriculum were some of the aspects highly prioritized by both teachers and principals.

Keywords: curriculum change, curriculum innovation, humanities curriculum, curriculum priorities

Procedia PDF Downloads 448

Authors: A. Kaddour, S. M. A. Bekkouche

Abstract:

Limiting heat losses during ventilation of indoor building spaces has become a basic aim for architects. Much experience has been gained in terms of ventilation of indoor spaces. Nevertheless, due to the complex applications, attempts to create a theoretical base for solving the problems related to the issue are limited, especially determining the minimum ventilation period required within a designated space. In this paper we have approached this matter, both theoretically and computationally. The conclusion we reached was that controlled ventilation of spaces through vent holes that successively open and close at regular time intervals can limit the excessive circulation of air masses, which in turn limits heat losses. Air change rates through open and tilted windows in rooms of residential buildings driven by atmospheric motions are investigated to evaluate natural ventilation concepts. Model of thermal building simulations is used. A separated sample storey and a sample single room in larger scales were used to measure air transport through window openings under the influence of the external pressure distribution.

Keywords: natural ventilation, temperature factor, air change rates, air circulation

Procedia PDF Downloads 442

Authors: Ehan Sabah Shukri, Wirachman Wisnoe

Abstract:

Temperature distribution investigation in a conical diffuser fitted with helical screw-tape with and without center-rod is studied numerically. A helical screw-tape is inserted in the diffuser to create swirl flow that helps to enhance the temperature distribution rate with inlet Reynolds number 4.3 x 104. Three pitch lengths ratios (Y/L = 0.153, 0.23 and 0.307) for the helical screw-tape with and without center-rod are simulated and compared. The geometry of the conical diffuser and the inlet condition for both arrangements are kept constant. Numerical findings show that the helical screw-tape inserts without center-rod perform significantly better than the helical tape inserts with center-rod in the conical diffuser.

Keywords: diffuser, temperature distribution, CFD, pitch ratio

Procedia PDF Downloads 409

Authors: Sathapath Kilaso

Abstract:

Nowadays people who live in the city tend to have a pet in order to relief the loneliness more than usual. It can be observed by the growth of the local pet industry. But the essentials of lifestyle of the urban people which is restricted by time and work might not allow the owner to take care of the pet properly. So this article will be about how to develop the prototype of pet care monitoring with Arduino Microcontroller. This prototype can be used to monitor the pet and its environment around the pet such as temperature (both pet’s temperature and outside temperature), humidity, food’s quantity, air’s quality and also be able to reduce the stress of the pet. This prototype can report the result back to the owner via online-channel such as website etc.

Keywords: pet care, Arduino Microcontroller, monitoring, prototype

Procedia PDF Downloads 358