Search results for: urban heat island
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 6851

Search results for: urban heat island

5501 Paratransit as Tool for Peri-Urban Connectivity: A Comparative Case Study of Indore and Bhopal, Madhya Pradesh, India

Authors: Sumit Rahangdale

Abstract:

This research paper is a comparative study of two BRTS cities of Madhya Pradesh (INDIA), Bhopal and Indore. Indore is the largest and most populous city of Madhya Pradesh, with heavy traffic, while Bhopal though being the capital of Madhya Pradesh is comparatively less developed and shows less traffic The cities show similarity in case of peri-urban nature, but variation is observed in transportation fare, where Indore has been able to reduce it but Bhopal couldn’t, one of the reason for it is the para-transit services. Indore can be considered as a successful model due to the low fares and can be implemented in other parts of the city. The research paper tries to identify relation of para-transit services with the peri-urban connectivity and provide a solution for the Bhopal case study.

Keywords: demand-supply-fare relationship, mobility and accessibility, paratransit, peri-urban connectivity

Procedia PDF Downloads 158
5500 Tetraploid Induction in the Yellowtail Tetra Astyanax altiparanae

Authors: Nivaldo Ferreira do Nascimento, Matheus Pereira-Santos, Nycolas Levy-Pereira, José Augusto Senhorini, George Shigueki Yasui, Laura Satiko Okada Nakaghi

Abstract:

Tetraploid individuals, which could produce diploid gametes, can be used for production of 100% triploid fish. Therefore, the aim of this study was to develop a tetraploidization protocol for A. altiparanae. We tested the effect of heat shock (40 °C; 2 min) at 16, 18, 20, 22, 24 and 26 minutes post fertilization (mpf). Untreated eggs were used as control. After hatching, ploidy status of the larvae was checked by flow cytometry. No difference were observed for the hatching rate between all treatments (P = 0.5974). However, we observed an increase in the larval abnormality in the heat shock treatments, in special at 22 (82.17 ± 6.66%) 24 (78.31 ±7.28%) and 26 mpf (79.01 ± 7.85%) in comparison with the control group (12.87 ± 4.46%). No tetraploid was observed at 16 and 18 mpf. The higher number of tetraploid individuals (52/55) was observed at 26 mpf. Our results showed that high percentages of tetraploids are obtained by heat shock (40°C; 2min) at 26 mpf, which could enable the mass production of triploid individuals in A. altiparanae.

Keywords: chromosome manipulation, polyploidy, flow cytometry, tetraploidization

Procedia PDF Downloads 318
5499 Analyzing the Shearing-Layer Concept Applied to Urban Green System

Authors: S. Pushkar, O. Verbitsky

Abstract:

Currently, green rating systems are mainly utilized for correctly sizing mechanical and electrical systems, which have short lifetime expectancies. In these systems, passive solar and bio-climatic architecture, which have long lifetime expectancies, are neglected. Urban rating systems consider buildings and services in addition to neighborhoods and public transportation as integral parts of the built environment. The main goal of this study was to develop a more consistent point allocation system for urban building standards by using six different lifetime shearing layers: Site, Structure, Skin, Services, Space, and Stuff, each reflecting distinct environmental damages. This shearing-layer concept was applied to internationally well-known rating systems: Leadership in Energy and Environmental Design (LEED) for Neighborhood Development, BRE Environmental Assessment Method (BREEAM) for Communities, and Comprehensive Assessment System for Building Environmental Efficiency (CASBEE) for Urban Development. The results showed that LEED for Neighborhood Development and BREEAM for Communities focused on long-lifetime-expectancy building designs, whereas CASBEE for Urban Development gave equal importance to the Building and Service Layers. Moreover, although this rating system was applied using a building-scale assessment, “Urban Area + Buildings” focuses on a short-lifetime-expectancy system design, neglecting to improve the architectural design by considering bio-climatic and passive solar aspects.

Keywords: green rating system, urban community, sustainable design, standardization, shearing-layer concept, passive solar architecture

Procedia PDF Downloads 560
5498 Energy System for Algerian Green Building in Tlemcen, North Africa

Authors: M. A. Boukli Hacene, N. E.Chabane Sari, A. Benzair

Abstract:

This article highlights a method for natural heating and cooling of systems in areas of moderate climate. Movement of air is generated inside a space by an underground piping system. In this paper, we discuss a feasibility study in Algeria of air-conditioning using a ground source heat pump (GSHP) with vertical mounting, coupled with a solar collector. This study consists of modeling ground temperature at different depths, for a clay soil in the city of Tlemcen. Our model is developed from the non-stationary heat equation for a homogeneous medium and takes into consideration the soil thermal diffusivity. It uses the daily ambient temperature during a typical year for the locality of Tlemcen. The study shows the feasibility of using a heating/cooling GSHP in the town of Tlemcen for the particular soil type; and indicates that the duration of air flow in the borehole has a major influence on the outgoing temperature drilling.

Keywords: green building, heat pump, insulation, climate change

Procedia PDF Downloads 204
5497 Natural Convection in Wavy-Wall Cavities Filled with Power-Law Fluid

Authors: Cha’o-Kuang Chen, Ching-Chang Cho

Abstract:

This paper investigates the natural convection heat transfer performance in a complex-wavy-wall cavity filled with power-law fluid. In performing the simulations, the continuity, Cauchy momentum and energy equations are solved subject to the Boussinesq approximation using a finite volume method. The simulations focus specifically on the effects of the flow behavior index in the power-law model and the Rayleigh number on the flow streamlines, isothermal contours and mean Nusselt number within the cavity. The results show that pseudoplastic fluids have a better heat transfer performance than Newtonian or dilatant fluids. Moreover, it is shown that for Rayleigh numbers greater than Ra=103, the mean Nusselt number has a significantly increase as the flow behavior index is decreased.

Keywords: non-Newtonian fluid, power-law fluid, natural convection, heat transfer enhancement, cavity, wavy wall

Procedia PDF Downloads 248
5496 Synthesis of Microencapsulated Phase Change Material for Adhesives with Thermoregulating Properties

Authors: Christin Koch, Andreas Winkel, Martin Kahlmeyer, Stefan Böhm

Abstract:

Due to environmental regulations on greenhouse gas emissions and the depletion of fossil fuels, there is an increasing interest in electric vehicles.To maximize their driving range, batteries with high storage capacities are needed. In most electric cars, rechargeable lithium-ion batteries are used because of their high energy density. However, it has to be taken into account that these batteries generate a large amount of heat during the charge and discharge processes. This leads to a decrease in a lifetime and damage to the battery cells when the temperature exceeds the defined operating range. To ensure an efficient performance of the battery cells, reliable thermal management is required. Currently, the cooling is achieved by heat sinks (e.g., cooling plates) bonded to the battery cells with a thermally conductive adhesive (TCA) that directs the heat away from the components. Especially when large amounts of heat have to be dissipated spontaneously due to peak loads, the principle of heat conduction is not sufficient, so attention must be paid to the mechanism of heat storage. An efficient method to store thermal energy is the use of phase change materials (PCM). Through an isothermal phase change, PCM can briefly absorb or release thermal energy at a constant temperature. If the phase change takes place in the transition from solid to liquid, heat is stored during melting and is released to the ambient during the freezing process upon cooling. The presented work displays the great potential of thermally conductive adhesives filled with microencapsulated PCM to limit peak temperatures in battery systems. The encapsulation of the PCM avoids the effects of aging (e.g., migration) and chemical reactions between the PCM and the adhesive matrix components. In this study, microencapsulation has been carried out by in situ polymerization. The microencapsulated PCM was characterized by FT-IR spectroscopy, and the thermal properties were measured by DSC and laser flash method. The mechanical properties, electrical and thermal conductivity, and adhesive toughness of the TCA/PCM composite were also investigated.

Keywords: phase change material, microencapsulation, adhesive bonding, thermal management

Procedia PDF Downloads 54
5495 How Autonomous Vehicles Transform Urban Policies and Cities

Authors: Adrián P. Gómez Mañas

Abstract:

Autonomous vehicles have already transformed urban policies and cities. This is the main assumption of our research, which aims to understand how the representations of the possible arrival of autonomous vehicles already transform priorities or actions in transport and more largely, urban policies. This research is done within the framework of a Ph.D. doctorate directed by Professor Xavier Desjardins at the Sorbonne University of Paris. Our hypotheses are: (i) the perspectives, representations, and imaginaries on autonomous vehicles already affect the stakeholders of urban policies; (ii) the discourses on the opportunities or threats of autonomous vehicles reflect the current strategies of the stakeholders. Each stakeholder tries to integrate a discourse on autonomous vehicles that allows them to change as little as possible their current tactics and strategies. The objective is to eventually make a comparison between three different cases: Paris, United Arab Emirates, and Bogota. We chose those territories because their contexts are very different, but they all have important interests in mobility and innovation, and they all have started to reflect on the subject of self-driving mobility. The main methodology used is to interview actors of the metropolitan area (local officials, leading urban and transport planners, influent experts, and private companies). This work is supplemented with conferences, official documents, press articles, and websites. The objective is to understand: 1) What they know about autonomous vehicles and where does their knowledge come from; 2) What they expect from autonomous vehicles; 3) How their ideas about autonomous vehicles are transforming their action and strategy in managing daily mobility, investing in transport, designing public spaces and urban planning. We are going to present the research and some preliminary results; we will show that autonomous vehicles are often viewed by public authorities as a lever to reach something else. We will also present that speeches are very influenced by local context (political, geographical, economic, etc.), creating an interesting balance between global and local influences. We will analyze the differences and similarities between the three cases and will try to understand which are the causes.

Keywords: autonomous vehicles, self-driving mobility, urban planning, urban mobility, transport, public policies

Procedia PDF Downloads 174
5494 Distribution Urban Public Spaces Among Riyadh Residential Neighborhoods

Authors: Abdulwahab Alalyani, Mahbub Rashid

Abstract:

Urban Open Space (UOS) a central role to promotes community health, including daily activities, but these resources may not available, accessible enough, and or equitably be distributed. This paper measures and compares spatial equity of the availability and accessibility UOS among low, middle, and high-income neighborhoods in Riyadh city. The measurement mothdulgy for the UOSavailability was by calculating the total of UOS with respect to the population total (m2/inhabitant) and the accessibility indicted by using walking distance of a 0.25 mi (0.4 km) buffering streets network.All UOS were mapped and measured using geographical information systems. To evaluate the significant differences in UOS availability and accessibility across low, medium, and high-income Riyadh neighborhoods, we used a One-way ANOVA analysis of covariance to test the differences.The findings are as follows; finding, UOSavailability was lower than global standers. Riyadh has only 1.13 m2 per capita of UOS, and the coverage accessible area by walking distance to UOS was lower than 50%. The final finding, spatial equity of the availability and accessibility, were significantly different among Riyadh neighborhoods based on socioeconomic status. The future development of UOS should be focused on increasing Urban park availability and should be given priority to those low-income and unhealthy communities.

Keywords: distribution urban open space, urban open space accessibility, spatial equity, riyadh city

Procedia PDF Downloads 77
5493 Characterization of Two Hybrid Welding Techniques on SA 516 Grade 70 Weldments

Authors: M. T. Z. Butt, T. Ahmad, N. A. Siddiqui

Abstract:

Commercially SA 516 Grade 70 is frequently used for the manufacturing of pressure vessels, boilers and storage tanks etc. in fabrication industry. Heat input is the major parameter during welding that may bring significant changes in the microstructure as well as the mechanical properties. Different welding technique has different heat input rate per unit surface area. Materials with large thickness are dealt with different combination of welding techniques to achieve required mechanical properties. In the present research two schemes: Scheme 1: SMAW (Shielded Metal Arc Welding) & GTAW (Gas Tungsten Arc Welding) and Scheme 2: SMAW & SAW (Submerged Arc Welding) of hybrid welding techniques have been studied. The purpose of these schemes was to study hybrid welding effect on the microstructure and mechanical properties of the weldment, heat affected zone and base metal area. It is significant to note that the thickness of base plate was 12 mm, also welding conditions and parameters were set according to ASME Section IX. It was observed that two different hybrid welding techniques performed on two different plates demonstrated that the mechanical properties of both schemes are more or less similar. It means that the heat input, welding techniques and varying welding operating conditions & temperatures did not make any detrimental effect on the mechanical properties. Hence, the hybrid welding techniques mentioned in the present study are favorable to implicate for the industry using the plate thickness around 12 mm thick.

Keywords: grade 70, GTAW, hybrid welding, SAW, SMAW

Procedia PDF Downloads 324
5492 Land Use Land Cover Changes in Response to Urban Sprawl within North-West Anatolia, Turkey

Authors: Melis Inalpulat, Levent Genc

Abstract:

In the present study, an attempt was made to state the Land Use Land Cover (LULC) transformation over three decades around the urban regions of Balıkesir, Bursa, and Çanakkale provincial centers (PCs) in Turkey. Landsat imageries acquired in 1984, 1999 and 2014 were used to determine the LULC change. Images were classified using the supervised classification technique and five main LULC classes were considered including forest (F), agricultural land (A), residential area (urban) - bare soil (R-B), water surface (W), and other (O). Change detection analyses were conducted for 1984-1999 and 1999-2014, and the results were evaluated. Conversions of LULC types to R-B class were investigated. In addition, population changes (1985-2014) were assessed depending on census data, the relations between population and the urban areas were stated, and future populations and urban area needs were forecasted for 2030. The results of LULC analysis indicated that urban areas, which are covered under R-B class, were expanded in all PCs. During 1984-1999 R-B class within Balıkesir, Bursa and Çanakkale PCs were found to have increased by 7.1%, 8.4%, and 2.9%, respectively. The trend continued in the 1999-2014 term and the increment percentages reached to 15.7%, 15.5%, and 10.2% at the end of 30-year period (1984-2014). Furthermore, since A class in all provinces was found to be the principal contributor for the R-B class, urban sprawl lead to the loss of agricultural lands. Moreover, the areas of R-B classes were highly correlated with population within all PCs (R2>0.992). Depending on this situation, both future populations and R-B class areas were forecasted. The estimated values of increase in the R-B class areas for Balıkesir, Bursa, and Çanakkale PCs were 1,586 ha, 7,999 ha and 854 ha, respectively. Due to this fact, the forecasted values for 2,030 are 7,838 ha, 27,866, and 2,486 ha for Balıkesir, Bursa, and Çanakkale, and thus, 7.7%, 8.2%, and 9.7% more R-B class areas are expected to locate in PCs in respect to the same order.

Keywords: landsat, LULC change, population, urban sprawl

Procedia PDF Downloads 246
5491 Application of Environmental Justice Concept in Urban Planning, The Peri-Urban Environment of Tehran as the Case Study

Authors: Zahra Khodaee

Abstract:

Environmental Justice (EJ) concept consists of multifaceted movements, community struggles, and discourses in contemporary societies that seek to reduce environmental risks, increase environmental protections, and generally reduce environmental inequalities suffered by minority and poor communities; a term that incorporates ‘environmental racism’ and ‘environmental classism,’ captures the idea that different racial and socioeconomic groups experience differential access to environmental quality. This article explores environmental justice as an urban phenomenon in urban planning and applies it in peri-urban environment of a metropolis. Tehran peri-urban environments which are the result of meeting the city- village- nature systems or «city-village junction» have gradually faced effects such as accelerated environmental decline, changes without land-use plan, and severe service deficiencies. These problems are instances of environmental injustice which make the planners to adjust the problems and use and apply the appropriate strategies and policies by looking for solutions and resorting to theories, techniques and methods related to environmental justice. In order to access to this goal, try to define environmental justice through justice and determining environmental justice indices to analysis environmental injustice in case study. Then, make an effort to introduce some criteria to select case study in two micro and micro levels. Qiyamdasht town as the peri-urban environment of Tehran metropolis is chosen and examined to show the existence of environmental injustice by questionnaire analysis and SPSS software. Finally, use AIDA technique to design a strategic plan and reduce environmental injustice in case study by introducing the better scenario to be used in policy and decision making areas.

Keywords: environmental justice, metropolis of Tehran, Qiyam, Dasht peri, urban settlement, analysis of interconnected decision area (AIDA)

Procedia PDF Downloads 467
5490 An Approach towards Smart Future: Ict Infrastructure Integrated into Urban Water Networks

Authors: Ahsan Ali, Mayank Ostwal, Nikhil Agarwal

Abstract:

Abstract—According to a World Bank report, millions of people across the globe still do not have access to improved water services. With uninterrupted growth of cities and urban inhabitants, there is a mounting need to safeguard the sustainable expansion of cities. Efficient functioning of the urban components and high living standards of the residents are needed to be ensured. The water and sanitation network of an urban development is one of its most essential parts of its critical infrastructure. The growth in urban population is leading towards increased water demand, and thus, the local water resources are severely strained. 'Smart water' is referred to water and waste water infrastructure that is able to manage the limited resources and the energy used to transport it. It enables the sustainable consumption of water resources through co-ordinate water management system, by integrating Information Communication Technology (ICT) solutions, intended at maximizing the socioeconomic benefits without compromising the environmental values. This paper presents a case study from a medium sized city in North-western Pakistan. Currently, water is getting contaminated due to the proximity between water and sewer pipelines in the study area, leading to public health issues. Due to unsafe grey water infiltration, the scarce ground water is also getting polluted. This research takes into account the design of smart urban water network by integrating ICT (Information and Communication Technology) with urban water network. The proximity between the existing water supply network and sewage network is analyzed and a design of new water supply system is proposed. Real time mapping of the existing urban utility networks will be projected with the help of GIS applications. The issue of grey water infiltration is addressed by providing sustainable solutions with the help of locally available materials, keeping in mind the economic condition of the area. To deal with the current growth of urban population, it is vital to develop new water resources. Hence, distinctive and cost effective procedures to harness rain water would be suggested as a part of the research study experiment.

Keywords: GIS, smart water, sustainability, urban water management

Procedia PDF Downloads 191
5489 Rural-Urban Drift: Labour Migration, Health-Seeking Behaviour Disparity in the Urban Slum of Madina, Ghana

Authors: Ransford Kwaku Afeadie

Abstract:

Purpose – The health challenges that characterises most of the migrants’ urban slums raise a lot of concern for their well-being. Health-seeking behaviour becomes an important step towards maintaining a healthy life. The importance of contextual issues is necessary to help meet specific community health needs and programmes. Therefore, this study aims to bridge the knowledge gap by investigating health-seeking behaviour disparity among rural-urban labour migrant slum dwellers before and after migration to the urban slums of Madina in the Greater Accra Region, Ghana. Design/methodology/approach – The author used explanatory sequential approach of research investigation. Questionnaire and interview guides were used to collect data from the respondents; however, in the absence of an existing reliable sampling frame, the various communities were selected by the use of cluster sampling proportional to size. At the second stage, a simple random sampling was used to select the various household heads. A total of 241 questionnaires were retrieved from the respondents representing a response rate of 100%. The author used the purposive sampling technique to conduct eight in-depth interviews and six key informants’ interviews. Findings – The author found various discrepancies in many of the activities that could fulfill substantial health-seeking behaviour in the slum as compared to migrant’s places of origin. The reason for coming to the slum amidst many settlements needs and low education background are the factors that accounted for this. This study, therefore, contradicts the proposition held by the health belief model. It is, therefore, important to note that contextual issues are key, in this case, rural-urban migrant slums present a different dynamic that must be taken into account when designing health programmes for such settings. Originality/value – Many, if not all the, studies on health-seeking behaviour have focused on urban slums without taking into account urban migrants’ slums. Such a failure to take into account the variations of the health needs of migrants’ urban slum settings can eventually lead to a mismatch of health programmes meant to address their challenges. Therefore, this study brings to the fore such variations that must be taken into account when designing health programmes. The study also indicates that even with the same people, there were disparities in terms of health-seeking behaviour in the slum and at places of origin.

Keywords: health-seeking behaviour, rural–urban migration, urban slums, health belief model

Procedia PDF Downloads 175
5488 Analyzing the Role of Visual Preferences for Designing of Urban Leftover Spaces

Authors: Jasim Azhar, Morten Gjerde

Abstract:

A city’s space is comprehended as a phenomenon that emerges from the ongoing negotiation between the constructed environment, urban processes, and bodily experience. Many spaces do not represent a static notion but are continually challenged and reconstituted. The ability to recognize those leftover spaces in the urban context is an integral part of an urban redevelopment process, where structured and layered approaches become useful in understanding to transform these spaces into places. Contemporary urban leftover spaces exist as a result of several factors and are present in every major city that often disrupts the flow of districts by creating visually unappealing places. These spaces can be designed, transformed and integrated so as to achieve environmental gains and social preferences. The paper explores how those small changes in visual quality of an urban leftover spaces in Wellington city influence a person’s experience significantly and its potential usage. These spaces can be seen as a catalyst for a change through an ecological sustainability’s framework. A creative and flexible design would lead to psychologically healthy places by improving the image of a city from within. The qualitative research is undertaken through the visual preference studies which will inform the planning initiatives by knowing what people feel about those visual changes in these leftover spaces. Those visual preferences can guide behavior and the emotional responses of different users for the redesign of those spaces with the meaningful attributes. The research is driven by the hypothesis that if the attributes are made visible, the likelihood of stimulating the interest of users should increase.

Keywords: leftover spaces, visual preferences, tactical urbanism, ecological sustainability

Procedia PDF Downloads 265
5487 On a Transient Magnetohydrodynamics Heat Transfer Within Radiative Porous Channel Due to Convective Boundary Condition

Authors: Bashiru Abdullahi, Isah Bala Yabo, Ibrahim Yakubu Seini

Abstract:

In this paper, the steady/transient MHD heat transfer within radiative porous channel due to convective boundary conditions is considered. The solution of the steady-state and that of the transient version were conveyed by Perturbation and Finite difference methods respectively. The heat transfer mechanism of the present work ascertains the influence of Biot number〖(B〗_i1), magnetizing parameter (M), radiation parameter(R), temperature difference, suction/injection(S) Grashof number (Gr) and time (t) on velocity (u), temperature(θ), skin friction(τ), and Nusselt number (Nu). The results established were discussed with the help of a line graph. It was found that the velocity, temperature, and skin friction decay with increasing suction/injection and magnetizing parameters while the Nusselt number upsurges with suction/injection at y = 0 and falls at y =1. The steady-state solution was in perfect agreement with the transient version for a significant value of time t. It is interesting to report that the Biot number has a cogent influence consequently, as its values upsurge the result of the present work slant the extended literature.

Keywords: heat transfer, thermal radiation, porous channel, MHD, transient, convective boundary condition

Procedia PDF Downloads 104
5486 Coupling Heat Transfer by Natural Convection and Thermal Radiation in a Storage Tank of LNG

Authors: R. Hariti, M. Saighi, H. Saidani-Scott

Abstract:

A numerical simulation of natural convection double diffusion, coupled with thermal radiation in unsteady laminar regime in a storage tank is carried out. The storage tank contains a liquefied natural gas (LNG) in its gaseous phase. Fluent, a commercial CFD package, based on the numerical finite volume method, is used to simulate the flow. The radiative transfer equation is solved using the discrete coordinate method. This numerical simulation is used to determine the temperature profiles, stream function, velocity vectors and variation of the heat flux density for unsteady laminar natural convection. Furthermore, the influence of thermal radiation on the heat transfer has been investigated and the results obtained were compared to those found in the literature. Good agreement between the results obtained by the numerical method and those taken on site for the temperature values.

Keywords: tank, storage, liquefied natural gas, natural convection, thermal radiation, numerical simulation

Procedia PDF Downloads 524
5485 Study of First Hydrogenation Kinetics at Different Temperatures of BCC Alloy 52Ti-12V-36Cr + x wt% Zr (x = 4, 8 & 12)

Authors: Ravi Prakash

Abstract:

The effects of Zr addition on kinetics and hydrogen absorption characteristics of BCC alloy 52Ti-12V-36Cr doped with x wt% of Zr (x = 0, 4, 8 & 12) was investigated. The samples have been characterized by X-ray diffraction, and activation study were made at four different temperatures- 100 oC, 200 oC, 300 oC and 400 oC. First hydrogenation kinetics of alloys were studied at 20 bar of hydrogen pressure and room temperature after giving heat treatment at different temperatures for 6 hours. Among the various Zr doped alloys studied, the composition 52Ti-12V-36Cr + 4wt% Zr shows maximum hydrogen storage capacity of 3.6wt%. Small amount of Zr shows advantageous effects on kinetics of alloy. It was also found out that alloys with the higher Zr concentration can be activated by giving heat treatment at lower temperatures. There is reduction in hydrogen storage capacity with increasing Zr content in the alloy primarily due to increasing abundance of secondary phase as established by X-Ray Diffraction and Scanning Electron Microscope results.

Keywords: hydrogen storage, metal hydrides, bcc alloy, heat treatment

Procedia PDF Downloads 50
5484 Finite Volume Method Simulations of GaN Growth Process in MOVPE Reactor

Authors: J. Skibinski, P. Caban, T. Wejrzanowski, K. J. Kurzydlowski

Abstract:

In the present study, numerical simulations of heat and mass transfer during gallium nitride growth process in Metal Organic Vapor Phase Epitaxy reactor AIX-200/4RF-S is addressed. Existing knowledge about phenomena occurring in the MOVPE process allows to produce high quality nitride based semiconductors. However, process parameters of MOVPE reactors can vary in certain ranges. Main goal of this study is optimization of the process and improvement of the quality of obtained crystal. In order to investigate this subject a series of computer simulations have been performed. Numerical simulations of heat and mass transfer in GaN epitaxial growth process have been performed to determine growth rate for various mass flow rates and pressures of reagents. According to the fact that it’s impossible to determine experimentally the exact distribution of heat and mass transfer inside the reactor during the process, modeling is the only solution to understand the process precisely. Main heat transfer mechanisms during MOVPE process are convection and radiation. Correlation of modeling results with the experiment allows to determine optimal process parameters for obtaining crystals of highest quality.

Keywords: Finite Volume Method, semiconductors, epitaxial growth, metalorganic vapor phase epitaxy, gallium nitride

Procedia PDF Downloads 379
5483 Climate Change Impact on Water Resources Management in Remote Islands Using Hybrid Renewable Energy Systems

Authors: Elissavet Feloni, Ioannis Kourtis, Konstantinos Kotsifakis, Evangelos Baltas

Abstract:

Water inadequacy in small dry islands scattered in the Aegean Sea (Greece) is a major problem regarding Water Resources Management (WRM), especially during the summer period due to tourism. In the present work, various WRM schemes are designed and presented. The WRM schemes take into account current infrastructure and include Rainwater Harvesting tanks and Reverse Osmosis Desalination Units. The energy requirements are covered mainly by wind turbines and/or a seawater pumped storage system. Sizing is based on the available data for population and tourism per island, after taking into account a slight increase in the population (up to 1.5% per year), and it guarantees at least 80% reliability for the energy supply and 99.9% for potable water. Evaluation of scenarios is carried out from a financial perspective, after calculating the Life Cycle Cost (LCC) of each investment for a lifespan of 30 years. The wind-powered desalination plant was found to be the most cost-effective practice, from an economic point of view. Finally, in order to estimate the Climate Change (CC) impact, six different CC scenarios were investigated. The corresponding rate of on-grid versus off-grid energy required for ensuring the targeted reliability for the zero and each climatic scenario was investigated per island. The results revealed that under CC the grid-on energy required would increase and as a result, the reduction in wind turbines and seawater pumped storage systems’ reliability will be in the range of 4 to 44%. However, the range of this percentage change does not exceed 22% per island for all examined CC scenarios. Overall, CC is proposed to be incorporated into the design process for WRM-related projects. Acknowledgements: This research is co-financed by Greece and the European Union (European Social Fund - ESF) through the Operational Program «Human Resources Development, Education and Lifelong Learning 2014-2020» in the context of the project “Development of a combined rain harvesting and renewable energy-based system for covering domestic and agricultural water requirements in small dry Greek Islands” (MIS 5004775).

Keywords: small dry islands, water resources management, climate change, desalination, RES, seawater pumped storage system, rainwater harvesting

Procedia PDF Downloads 100
5482 The Concepts of Urban Sustainable Development and Smart Cities: In the Understanding of Academia and the European Union

Authors: Wolfgang Haupt

Abstract:

When considering the future city one repeatedly comes across two sometimes sparsely differentiated terms: Sustainable and smart. ‘A European Strategy for Smart, Sustainable, and Inclusive Growth’, this is how the European Commission named its current growth strategy. Thus, Europe should become smarter and more sustainable. Both, the smart and the sustainable city represent a positive vision of urban development as well as a subject area for contemporary and future urban policies. However, more clarity on what is actually behind these terminologies is required. The paper analyses how the terms are defined academically and how this academic understanding is represented in the funding mechanisms of European urban policies. The theoretical framework is mainly based on sources such as journal articles and policy reports. It became clear that despite some similarities, such as the broad field of work or the tendency to operationalize the terms by defining sub-categories, both ideas are distinctly different in terms of the development history, the main driving forces behind and the theoretical scope. Moreover, the significantly more comprehensively defined term sustainability has found its way into the centre of European regional funding policies. On the contrary, the smart city vision still lacks terminological and content-related clarity and as a consequence, the corresponding European funding landscape is more small-scaled and less customized.

Keywords: European spatial policy, European union, smart city, urban sustainable development

Procedia PDF Downloads 351
5481 Strawberry Productivity of Peri-Urban and Urban Locations across Southeast Michigan, USA

Authors: Maria E. Laconi, Kyla D. Scherr, Mary A. Jamieson

Abstract:

Human populations in urban environments have rapidly grown in recent decades. Consequently, the intensity of land-use and development has also increased in many urban and peri-urban environments. Some cities, such as Detroit, Michigan, USA, have embraced urban agriculture and local food production. Little is known, however, about how the local and landscape scale environmental factors influence crop productivity on urban farms. Our study aims to evaluate factors influencing the productivity of strawberries on community farms and gardens in the Detroit metropolitan area. Strawberries are one of few fruits that can provide an abundant harvest just after the first season of being planted, which is ideal for urban gardeners in developed areas. In the spring of 2016, we planted six different strawberry cultivars (three everbearing and three June bearing varieties) at five farm sites in Wayne and Oakland County (six replicate plants per cultivar per site). We surveyed flower and fruit phenology and production for everbearing varieties weekly (flowers for June bearing varieties were removed to enhance productivity in the coming growing season). Additionally, we conducted one initial 36hr pollinator survey in mid-September during peak fruit production and characterized local and landscape scale land-cover data. Preliminary results and observations from this first year of our study revealed that strawberry production varied significantly by site. Specifically, productivity at our most northern site appeared to suffer from delayed phenology and early frost damage to ripening strawberries. Bee abundance and diversity also differed among farms, though further surveys are needed to adequately inventory the pollinator community. Finally, strawberry cultivars demonstrated significant differences in the number and size of fruits produced. We plan to continue this study in the coming years, increasing the number of sites surveyed and number of pollinator sampling events. Our study aims to inform strategies for enhancing crop productivity on urban and peri-urban farms.

Keywords: insect pollination, strawberry productivity, sustainable agriculture, urban gardening

Procedia PDF Downloads 262
5480 Effect of Urbanization on Basic Environmental Components

Authors: Sehba Saleem

Abstract:

A country with a spread of only 2.4 percent of the total land surface area of the world, India is home to 17.5 percent of the world population. This fact is sufficient enough to delineate as well as simultaneously bringing to fore the paradox which exists between land and human population. It is evident that the relation which exists between both is an unequal one where the latter has the ability to multiply self, but the former remains constant. This unequal relation that exists has very significantly contributed to the depletion in the quality of land. This is because construction of every kind and nature has been forced on the land to assimilate the ever increasing population which has altered the not only the land but the environment which existed on the land. To get behind this alteration, it becomes imperative to delve into concepts like urbanization, ecology and their amalgam viz. urban ecology. The concept of urban ecology does not only involve study of buildings, flora, and fauna which exists in a given land space. It goes further into establishing a relation between construction on land and the consequent harm, which the same is causing to the environmental resources like air, water etc. This paper shall try cerebrating concepts of urbanization, ecology and urban ecology in the light of relation which exists between man and nature.

Keywords: asymmetrical growth, environment, urbanisation, urban space

Procedia PDF Downloads 303
5479 Comparative Life Cycle Assessment of an Extensive Green Roof with a Traditional Gravel-Asphalted Roof: An Application for the Lebanese Context

Authors: Makram El Bachawati, Rima Manneh, Thomas Dandres, Carla Nassab, Henri El Zakhem, Rafik Belarbi

Abstract:

A vegetative roof, also called a garden roof, is a "roofing system that endorses the growth of plants on a rooftop". Garden roofs serve several purposes for a building, such as embellishing the roofing system, enhancing the water management, and reducing the energy consumption and heat island effects. Lebanon is a Middle East country that lacks the use of a sustainable energy system. It imports 98% of its non-renewable energy from neighboring countries and suffers flooding during heavy rains. The objective of this paper is to determine if the implementation of vegetative roofs is effectively better than the traditional roofs for the Lebanese context. A Life Cycle Assessment (LCA) is performed in order to compare an existing extensive green roof to a traditional gravel-asphalted roof. The life cycle inventory (LCI) was established and modeled using the SimaPro 8.0 software, while the environmental impacts were classified using the IMPACT 2002+ methodology. Results indicated that, for the existing extensive green roof, the waterproofing membrane and the growing medium were the highest contributors to the potential environmental impacts. When comparing the vegetative to the traditional roof, results showed that, for all impact categories, the extensive green roof had the less environmental impacts.

Keywords: life cycle assessment, green roofs, vegatative roof, environmental impact

Procedia PDF Downloads 447
5478 Comparative Ethnography and Urban Health: A Multisite Study on Obesogenic Cities

Authors: Carlos Rios Llamas

Abstract:

Urban health challenges, like the obesity epidemic, need to be studied from a dialogue between different disciplines and geographical conditions. Public health uses quantitative analysis and local samples, but qualitative data and multisite analysis would help to better understand how obesity has become a health problem. In the last decades, obesity rates have increased in most of the countries, especially in the Western World. Concerned about the problem, the American Medical Association has recently voted obesity as a disease. Suddenly, a ‘war on obesity’ attracted scientists from different disciplines to explore various ways to control and even reverse the trends. Medical sciences have taken the advance with quantitative methodologies focused on individual behaviors. Only a few scientist have extended their studies to the environment where obesity is produced as social risk, and less of them have taken into consideration the political and cultural aspects. This paper presents a multisite ethnography in South Bronx, USA, La Courneuve, France, and Lomas del Sur, Mexico, where obesity rates are as relevant as urban degradation. The comparative ethnography offers a possibility to unveil the mechanisms producing health risks from the urban tissue. The analysis considers three main categories: 1) built environment and access to food and physical activity, 2) biocultural construction of the healthy body, 3) urban inequalities related to health and body size. Major findings from a comparative ethnography on obesogenic environments, refer to the anthropological values related to food and body image, as well as the multidimensional oppression expressed in fat people who live in stigmatized urban zones. At the end, obesity, like many other diseases, is the result of political and cultural constructions structured in urbanization processes.

Keywords: comparative ethnography, urban health, obesogenic cities, biopolitics

Procedia PDF Downloads 232
5477 Effect of Surfactant on Thermal Conductivity of Ethylene Glycol/Silver Nanofluid

Authors: E. C. Muhammed Irshad

Abstract:

Nanofluids are a new class of solid-liquid colloidal mixture consisting of nanometer sized (< 100nm) solid particles suspended in heat transfer fluids such as water, ethylene/propylene glycol etc. Nanofluids offer excellent scope of enhancing thermal conductivity of common heat transfer fluids and it leads to enhancement of the heat transfer coefficient. In the present study, silver nanoparticles are dispersed in ethylene glycol water mixture. Low volume concentrations (0.05%, 0.1% and 0.15%) of silver nanofluids were synthesized. The thermal conductivity of these nanofluids was determined with thermal property analyzer (KD2 pro apparatus) and heat transfer coefficient was found experimentally. Initially, the thermal conductivity and viscosity of nanofluids were calculated with various correlations at different concentrations and were compared. Thermal conductivity of silver nanofluid at 0.02% and 0.1% concentration of silver nanoparticle increased to 23.3% and 27.7% for Sodium Dodecyl Sulfate (SDS) and to 33.6% and 36.7% for Poly Vinyl Pyrrolidone (PVP), respectively. The nanofluid maintains the stability for two days and it starts to settle down due to high density of silver. But it shows good improvement in the thermal conductivity for low volume concentration and it also shows better improvement with Poly Vinyl Pyrrolidone (PVP) surfactant than Sodium Dodecyl Sulfate (SDS).

Keywords: k-thermal conductivity, sodium dodecyl sulfate, vinyl pyrrolidone, mechatronics engineering

Procedia PDF Downloads 297
5476 Colombia Fossil Fuel Policies and Their Impact on Urban Air Quality

Authors: Ruth Catacolí, Hector Garcia

Abstract:

Colombia Urban Areas shows a decreasing of their air quality, no matter the actions developed by the Government facing the mitigation of pressure factors related with air pollution. Examples of these actions were the fossil fuel quality improvement policies (FFQI). This study evaluated the impact of three FFQI in the air quality of Bogotá during the period 1990 - 2006: The phase-out of lead in the gasoline; the sulfur reduction in diesel oil consumed in Bogotá and the oxygenation of gasoline through the addition of ethanol. The results indicate that only the policy of phase-out of lead in gasoline has been effective, showing dropping of lead oxides concentration in the air. Some stakeholders believe that the FFQI evaluated in the study are environmental policies, but no one of these policies has been supported by an environmental impact assessment that shows specific benefits in air quality. The research includes some fuel policy elements to achieve positive impact on the air quality in the urban centers of Colombia.

Keywords: policy assessment, fuel quality, urban air quality, air quality management

Procedia PDF Downloads 307
5475 Combined Effect of Heat Stimulation and Delayed Addition of Superplasticizer with Slag on Fresh and Hardened Property of Mortar

Authors: Faraidoon Rahmanzai, Mizuki Takigawa, Yu Bomura, Shigeyuki Date

Abstract:

To obtain the high quality and essential workability of mortar, different types of superplasticizers are used. The superplasticizers are the chemical admixture used in the mix to improve the fluidity of mortar. Many factors influenced the superplasticizer to disperse the cement particle in the mortar. Nature and amount of replaced cement by slag, mixing procedure, delayed addition time, and heat stimulation technique of superplasticizer cause the varied effect on the fluidity of the cementitious material. In this experiment, the superplasticizers were heated for 1 hour under 60 °C in a thermostatic chamber. Furthermore, the effect of delayed addition time of heat stimulated superplasticizers (SP) was also analyzed. This method was applied to two types of polycarboxylic acid based ether SP (precast type superplasticizer (SP2) and ready-mix type superplasticizer (SP1)) in combination with a partial replacement of normal Portland cement with blast furnace slag (BFS) with 30% w/c ratio. On the other hands, the fluidity, air content, fresh density, and compressive strength for 7 and 28 days were studied. The results indicate that the addition time and heat stimulation technique improved the flow and air content, decreased the density, and slightly decreased the compressive strength of mortar. Moreover, the slag improved the flow of mortar by increasing the amount of slag, and the effect of external temperature of SP on the flow of mortar was decreased. In comparison, the flow of mortar was improved on 5-minute delay for both kinds of SP, but SP1 has improved the flow in all conditions. Most importantly, the transition points in both types of SP appear to be the same, at about 5±1 min.  In addition, the optimum addition time of SP to mortar should be in this period.

Keywords: combined effect, delay addition, heat stimulation, flow of mortar

Procedia PDF Downloads 179
5474 Thermal Comfort in Office Rooms in a Historic Building with Modernized Heating, Ventilation and Air Conditioning Systems

Authors: Hossein Bakhtiari, Mathias Cehlin, Jan Akander

Abstract:

Envelopes with low thermal performance is a common characteristic in many European historic buildings which leads to higher energy demand for heating and cooling as well as insufficient thermal comfort for the occupants. This paper presents the results of a study on the thermal comfort in the City Hall (Rådhuset) in Gävle, Sweden. This historic building is currently used as an office building. It is equipped with two relatively modern mechanical heat recovery ventilation systems with displacement ventilation supply devices in the offices. The district heating network heats the building via pre-heat supply air and radiators. Summer cooling comes from an electric heat pump that rejects heat into the exhaust ventilation air. A building management system controls HVAC equipment (heating, ventilation and air conditioning). The methodology is based on on-site measurements, data logging on the management system and evaluating the occupants’ perception of a summer and a winter period indoor environment using a standardized questionnaire. The main aim of the study is to investigate whether or not it is enough to have modernized HVAC systems to get adequate thermal comfort in a historic building with poor envelope performance used as an office building in Nordic climate conditions.

Keywords: historic buildings, on-site measurements, standardized questionnaire, thermal comfort

Procedia PDF Downloads 356
5473 Evaluation of the Urban Regeneration Project: Land Use Transformation and SNS Big Data Analysis

Authors: Ju-Young Kim, Tae-Heon Moon, Jung-Hun Cho

Abstract:

Urban regeneration projects have been actively promoted in Korea. In particular, Jeonju Hanok Village is evaluated as one of representative cases in terms of utilizing local cultural heritage sits in the urban regeneration project. However, recently, there has been a growing concern in this area, due to the ‘gentrification’, caused by the excessive commercialization and surging tourists. This trend was changing land and building use and resulted in the loss of identity of the region. In this regard, this study analyzed the land use transformation between 2010 and 2016 to identify the commercialization trend in Jeonju Hanok Village. In addition, it conducted SNS big data analysis on Jeonju Hanok Village from February 14th, 2016 to March 31st, 2016 to identify visitors’ awareness of the village. The study results demonstrate that rapid commercialization was underway, unlikely the initial intention, so that planners and officials in city government should reconsider the project direction and rebuild deliberate management strategies. This study is meaningful in that it analyzed the land use transformation and SNS big data to identify the current situation in urban regeneration area. Furthermore, it is expected that the study results will contribute to the vitalization of regeneration area.

Keywords: land use, SNS, text mining, urban regeneration

Procedia PDF Downloads 280
5472 Investigation on Remote Sense Surface Latent Heat Temperature Associated with Pre-Seismic Activities in Indian Region

Authors: Vijay S. Katta, Vinod Kushwah, Rudraksh Tiwari, Mulayam Singh Gaur, Priti Dimri, Ashok Kumar Sharma

Abstract:

The formation process of seismic activities because of abrupt slip on faults, tectonic plate moments due to accumulated stress in the Earth’s crust. The prediction of seismic activity is a very challenging task. We have studied the changes in surface latent heat temperatures which are observed prior to significant earthquakes have been investigated and could be considered for short term earthquake prediction. We analyzed the surface latent heat temperature (SLHT) variation for inland earthquakes occurred in Chamba, Himachal Pradesh (32.5 N, 76.1E, M-4.5, depth-5km) nearby the main boundary fault region, the data of SLHT have been taken from National Center for Environmental Prediction (NCEP). In this analysis, we have calculated daily variations with surface latent heat temperature (0C) in the range area 1⁰x1⁰ (~120/KM²) with the pixel covering epicenter of earthquake at the center for a three months period prior to and after the seismic activities. The mean value during that period has been considered in order to take account of the seasonal effect. The monthly mean has been subtracted from daily value to study anomalous behavior (∆SLHT) of SLHT during the earthquakes. The results found that the SLHTs adjacent the epicenters all are anomalous high value 3-5 days before the seismic activities. The abundant surface water and groundwater in the epicenter and its adjacent region can provide the necessary condition for the change of SLHT. To further confirm the reliability of SLHT anomaly, it is necessary to explore its physical mechanism in depth by more earthquakes cases.

Keywords: surface latent heat temperature, satellite data, earthquake, magnetic storm

Procedia PDF Downloads 119