Search results for: beam-like structures.
3125 Series Network-Structured Inverse Models of Data Envelopment Analysis: Pitfalls and Solutions
Authors: Zohreh Moghaddas, Morteza Yazdani, Farhad Hosseinzadeh
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Nowadays, data envelopment analysis (DEA) models featuring network structures have gained widespread usage for evaluating the performance of production systems and activities (Decision-Making Units (DMUs)) across diverse fields. By examining the relationships between the internal stages of the network, these models offer valuable insights to managers and decision-makers regarding the performance of each stage and its impact on the overall network. To further empower system decision-makers, the inverse data envelopment analysis (IDEA) model has been introduced. This model allows the estimation of crucial information for estimating parameters while keeping the efficiency score unchanged or improved, enabling analysis of the sensitivity of system inputs or outputs according to managers' preferences. This empowers managers to apply their preferences and policies on resources, such as inputs and outputs, and analyze various aspects like production, resource allocation processes, and resource efficiency enhancement within the system. The results obtained can be instrumental in making informed decisions in the future. The top result of this study is an analysis of infeasibility and incorrect estimation that may arise in the theory and application of the inverse model of data envelopment analysis with network structures. By addressing these pitfalls, novel protocols are proposed to circumvent these shortcomings effectively. Subsequently, several theoretical and applied problems are examined and resolved through insightful case studies.Keywords: inverse models of data envelopment analysis, series network, estimation of inputs and outputs, efficiency, resource allocation, sensitivity analysis, infeasibility
Procedia PDF Downloads 393124 Development and Characterization of Ceramic-Filled Composite Filaments and Functional Structures for Fused Deposition Modeling
Authors: B. Khatri, K. Lappe, M. Habedank, T. Müller, C. Megnin, T. Hanemann
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We present a process flow for the development of ceramic-filled polymer composite filaments compatible with the fused deposition modeling (FDM) 3D printing process. Thermoplastic-ceramic composites were developed using acrylonitrile butadiene styrene (ABS) and 10- and 20 vol.% barium titanate (BaTiO3) powder (corresponding to 39.47- and 58.23 wt.% respectively) and characterized for their flow properties. To make them compatible with the existing FDM process, the composites were extruded into filaments. These composite filaments were subsequently structured into tensile stress specimens using a commercially available FDM 3D printer and characterized for their mechanical properties. Rheometric characterization of the material composites revealed non-Newtonian behavior with the viscosity logarithmically decreasing over increasing shear rates, as well as higher viscosities for samples with higher BaTiO3 filler content for a given shear rate (with the ABS+20vol.% BaTiO3 composite being over 50% more viscous compared to pure ABS at a shear rate of 1x〖10〗^3 s^(-1)). Mechanical characterization of the tensile stress specimens exhibited increasingly brittle behavior as well as a linearly decreasing ultimate tensile strength of the material composites with increasing volumetric ratio of BaTiO3 (from σ_max=32.4MPa for pure ABS to σ_max=21.3MPa for ABS+20vol.% BaTiO3). Further studies being undertaken include the development of composites with higher filler concentrations, sintering of the printed composites to yield pure dielectric structures and the determination of the dielectric characteristics of the composites.Keywords: ceramic composites, fused deposition modeling, material characterization, rapid prototyping
Procedia PDF Downloads 3283123 Retrofitting Adaptive Reuse into Palaces of Northern India
Authors: Shefali Nayak
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The architectural appeal, familiarity, and idiom of culturally significant structures are due to societal attachment to various movements, historical association or deviation. Generally, the urge to preserve a building in the northern part of India is driven either by emotional dogma or rational thinking, but, it is also influenced by traditional affinity. The northern region of India has an assortment of palaces and Havelis belonging to various time periods and families with vernacular yet signature style of architecture. Many of them are either successfully conserved by being put into adaptive reuse and some of them have been midst controversies and continued to remain in ruins. The research focuses on comparing successful examples of adaptive reuse such as Neemrana, Mehrangargh Fort palace with a few other merchant havelis converted into heritage hotels. Furthermore, evaluates the architectural aspects of structure, materials, plumbing and electrical installations, as well as specific challenges faced by heritage professionals practicing sustainability, while respecting traditional feelings of various stakeholders. This paper concludes through the analysis of the case study that, its highly unlikely for sustainable design cannot be used as a stand-alone application for heritage structures or cities, it needs the support of architecture conservation to be put into practice. However, it is often demanding to fit a new use of a building into an aged structure. This paper records modern-day generic requirements that reflect challenges faced by different architects, while conserving a heritage structure and retrofitting it into today's requisites. The research objective is to establish how conservation, restoration, and urban regeneration are closely related to sustainable architecture in historical cities.Keywords: architecture conservation, architecture heritage, adaptive reuse, retrofitting, sustainability, urban regeneration
Procedia PDF Downloads 1723122 Evaluating Probable Bending of Frames for Near-Field and Far-Field Records
Authors: Majid Saaly, Shahriar Tavousi Tafreshi, Mehdi Nazari Afshar
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Most reinforced concrete structures are designed only under heavy loads have large transverse reinforcement spacing values, and therefore suffer severe failure after intense ground movements. The main goal of this paper is to compare the shear- and axial failure of concrete bending frames available in Tehran using incremental dynamic analysis under near- and far-field records. For this purpose, IDA analyses of 5, 10, and 15-story concrete structures were done under seven far-fault records and five near-faults records. The results show that in two-dimensional models of short-rise, mid-rise and high-rise reinforced concrete frames located on Type-3 soil, increasing the distance of the transverse reinforcement can increase the maximum inter-story drift ratio values up to 37%. According to the existing results on 5, 10, and 15-story reinforced concrete models located on Type-3 soil, records with characteristics such as fling-step and directivity create maximum drift values between floors more than far-fault earthquakes. The results indicated that in the case of seismic excitation modes under earthquake encompassing directivity or fling-step, the probability values of failure and failure possibility increasing rate values are much smaller than the corresponding values of far-fault earthquakes. However, in near-fault frame records, the probability of exceedance occurs at lower seismic intensities compared to far-fault records.Keywords: IDA, failure curve, directivity, maximum floor drift, fling step, evaluating probable bending of frames, near-field and far-field earthquake records
Procedia PDF Downloads 983121 Through-Bolt Moment Connection in HSS Column
Authors: Bardia Khafaf, Mehrdad Ghaffari, Amir Hussein Samakar
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It is currently desirable to use Hollow Square Sections (HSS) in moment resistant structures in construction of building because they offer fewer restrictions for designing and more useful space while adhering to build design codes. This paper present a through bolt connection in HSS column. This connection meets building code standards that require the moment resistant connections to deflect and absorb energy resulting from gravity and seismic loads. Connection through bolts is installed and pretension to provide the connection strength needed to make a beam–column moment rigid zone. A rigid joint is typically used to resist lateral forces by holding columns and beams fixed in relation to one another. With bolted moment frames using HSS columns, a through–bolt connection could be used to secure the beam and end plate to the column. However, when multiple columns and beams are used to span a length of building, the use of through-bolts would necessities aligning multiple beams simultaneously to the columns. In the case of a linear span, the assembly process requires the holes of a first beam end plate to be aligned with through bolt holes in a column and aligning the holes of a second, opposing beam plate with the column through bolt, then inserting the through bolts in each hole for tightening with nuts and washers. In moment resistant building, a problem arises when assembling beams to columns where multiple beams and columns are required. Through bolt, moment connections are among the economical, practical and not difficult rigid steel connection for HSS column building. In this paper, the results of numerous analytical studies performed for moment structures with HSS columns with through bolt based on AISC standard codes are shown.Keywords: through bolt, moment resistant connection, HSS columns section, construction engineering
Procedia PDF Downloads 4543120 A Case Study of Alkali-Silica Reaction Induced Consistent Damage and Strength Degradation Evaluation in a Textile Mill Building Due to Slow-Reactive Aggregates
Authors: Ahsan R. Khokhar, Fizza Hassan
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Alkali-Silica Reaction (ASR) has been recognized as a potential cause of concrete degradation in the world since the 1940s. In Pakistan, mega hydropower structures like dams, weirs constructed from aggregates extracted from a local riverbed exhibited different levels of alkali-silica reactivity over an extended service period. The concrete expansion potential due to such aggregates has been categorized as slow-reactive. Apart from hydropower structures, ASR existence has been identified in the concrete structural elements of a Textile Mill building which used aggregates extracted from the nearby riverbed. The original structure of the Textile Mill was erected in the 80s with the addition of a textile ‘sizing and wrapping’ hall constructed in the 90s. In the years to follow, intensive spalling was observed in the structural members of the subject hall; enough to threat to the overall stability of the building. Limitations such as incomplete building data posed hurdles during the detailed structural investigation. The paper lists observations made while assessing the extent of damage and its effect on the building hall structure. Core testing and Petrographic tests were carried out as per the ASTM standards for strength degradation analysis followed by the identifying its root cause. Results confirmed significant structural strength reduction because of ASR which necessitated the formulation of an immediate re-strengthening solution. The paper also discusses the possible tracks of rehabilitative measures which are being adapted to stabilize the structure and seize further concrete expansion.Keywords: Alkali-Silica Reaction (ASR), concrete strength degradation, damage assessment, damage evaluation
Procedia PDF Downloads 1253119 Experimental Investigation on the Fire Performance of Corrugated Sandwich Panels made from Renewable Material
Authors: Avishek Chanda, Nam Kyeun Kim, Debes Bhattacharyya
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The use of renewable substitutes in various semi-structural and structural applications has experienced an increase since the last few decades. Sandwich panels have been used for many decades, although research on understanding the effects of the core structures on the panels’ fire-reaction properties is limited. The current work investigates the fire-performance of a corrugated sandwich panel made from renewable, biodegradable, and sustainable material, plywood. The bench-scale fire testing apparatus, cone-calorimeter, was employed to evaluate the required fire-reaction properties of the sandwich core in a panel configuration, with three corrugated layers glued together with face-sheets under a heat irradiance of 50 kW/m2. The study helped in documenting a unique heat release trend associated with the fire performance of the 3-layered corrugated sandwich panels and in understanding the structural stability of the samples in the event of a fire. Furthermore, the total peak heat release rate was observed to be around 421 kW/m2, which is significantly low compared to many polymeric materials in the literature. The total smoke production was also perceived to be very limited compared to other structural materials, and the total heat release was also nominal. The time to ignition of 21.7 s further outlined the advantages of using the plywood component since polymeric composites, even with flame-retardant additives, tend to ignite faster. Overall, the corrugated plywood sandwich panels had significant fire-reaction properties and could have important structural applications. The possible use of structural panels made from bio-degradable material opens a new avenue for the use of similar structures in sandwich panel preparation.Keywords: corrugated sandwich panel, fire-reaction properties, plywood, renewable material
Procedia PDF Downloads 1493118 The Meaning Structures of Political Participation of Young Women: Preliminary Findings in a Practical Phenomenology Study
Authors: Amanda Aliende da Matta, Maria del Pilar Fogueiras Bertomeu, Valeria de Ormaechea Otalora, Maria Paz Sandin Esteban, Miriam Comet Donoso
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This communication presents the preliminary emerging themes in a research on political participation of young women. The study follows a qualitative methodology; in particular, the applied hermeneutic phenomenological method, and the general objective of the research is to give an account of the experience of political participation as young women. The study participants are women aged 18 to 35 who have experience in political participation. The techniques of data collection are the descriptive story and the phenomenological interview. With respect to the first methodological steps, these have been: 1) collect and select stories of lived experience in political participation, 2) select descriptions of lived experience (DLEs) in political participation of the chosen stories, 3) to prepare phenomenological interviews from the selected DLEs, 4) to conduct phenomenological thematic analysis (PTA) of the DLEs. We have so far initiated the PTA on 5 vignettes. Hermeneutic phenomenology as a research approach is based on phenomenological philosophy and applied hermeneutics. Phenomenology is a descriptive philosophy of pure experience and essences, through which we seek to capture an experience at its origins without categorizing, interpreting or theorizing it. Hermeneutics, on the other hand, may be defined as a philosophical current that can be applied to data analysis. Max Van Manen wrote that hermeneutic phenomenology is a method of abstemious reflection on the basic structures of the lived experience of human existence. In hermeneutic phenomenology we focus, then, on the way we experience “things” in the first person, seeking to capture the world exactly as we experience it, not as we categorize or conceptualize it. In this study, the empirical methods used were: Lived experience description (written) and conversational interview. For these short stories, participants were asked: “What was your lived experience of participation in politics as a young woman? Can you tell me any stories or anecdotes that you think exemplify or typify your experience?”. The questions were accompanied by a list of guidelines for writing descriptive vignettes. And the analytical method was PTA. Among the provisional results, we found preliminary emerging themes, which could in the advance of the investigation result in meaning structures of political participation of young women. They are the following: - Complicity may be inherent/essential in political participation as a young woman; - Feelings may be essential/inherent in political participation as a young woman; - Hope may be essential in authentic political participation as a young woman; - Frustration may be essential in authentic political participation as a young woman; - Satisfaction may be essential in authentic political participation as a young woman; - There may be tension between individual/collective inherent/essential in political participation as a young woman; - Political participation as a young woman may include moments of public demonstration.Keywords: applied hermeneutic phenomenology, hermeneutics, phenomenology, political participation
Procedia PDF Downloads 843117 Comparison of the Existing Damage Indices in Steel Moment-Resisting Frame Structures
Authors: Hamid Kazemi, Abbasali Sadeghi
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Assessment of seismic behavior of frame structures is just done for evaluating life and financial damages or lost. The new structural seismic behavior assessment methods have been proposed, so it is necessary to define a formulation as a damage index, which the damage amount has been quantified and qualified. In this paper, four new steel moment-resisting frames with intermediate ductility and different height (2, 5, 8, and 12-story) with regular geometry and simple rectangular plan were supposed and designed. The three existing groups’ damage indices were studied, each group consisting of local index (Drift, Maximum Roof Displacement, Banon Failure, Kinematic, Banon Normalized Cumulative Rotation, Cumulative Plastic Rotation and Ductility), global index (Roufaiel and Meyer, Papadopoulos, Sozen, Rosenblueth, Ductility and Base Shear), and story (Banon Failure and Inter-story Rotation). The necessary parameters for these damage indices have been calculated under the effect of far-fault ground motion records by Non-linear Dynamic Time History Analysis. Finally, prioritization of damage indices is defined based on more conservative values in terms of more damageability rate. The results show that the selected damage index has an important effect on estimation of the damage state. Also, failure, drift, and Rosenblueth damage indices are more conservative indices respectively for local, story and global damage indices.Keywords: damage index, far-fault ground motion records, non-linear time history analysis, SeismoStruct software, steel moment-resisting frame
Procedia PDF Downloads 2873116 Free Raducal Scavenging Activity of Fractionated Extract and Structural Elucidation of Isolated Compounds from Hydrocotyl Bonariensis Comm. Ex Lam Leaves
Authors: Emmanuel O Ajani, Sabiu S, Mariam Zakari, Fisayo A Bamisaye
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Hydrocotyl bonariensis is a plant which anticataractogenic potentials have been reported. In the present study an attempt was made to evaluate the in vitro antioxidant activity of the fractionates of the leaves extract and also characterize some of its chemical constituents. DPPH, H₂O₂, OH and NO free radical scavenging, metal chelating and reducing power activity was used to evaluate the antioxidant activity of the crude extract fractionates. Fresh leaves of Hydrocotyl bonariensis leaves were extracted in 70% methanol. The extract was partitioned with different solvent system of increasing polarity (n-hexane, chloroform, ethyl acetate methanol and water). Compounds were isolated from the aqueous practitionate using accelerated gradient chromatography, vacuum liquid chromatography, preparative TLC and conventional column chromatography. The presence of the chemical groups was established with HPLC and Fourier Transform Infra Red. The structures of isolated compounds were elucidated by spectroscopic study and chemical shifts. Data from the study indicates that all the fractionates contain compounds with free radical scavenging activity. This activity was more pronounced in the aqueous fractionate (DPPH IC₅₀, 0025 ± 0.011 mg/ml, metal chelating capacity 27.5%, OH- scavenging IC₅₀, 0.846 ± 0.037 mg/ml, H₂O₂ scavenging IC₅₀ 0.521 ± 0.015 mg/ml, reducing power IC₅₀ 0.248 ± 0.025 mg/ml and NO scavenging IC₅₀ 0.537 ± 0.038 mg/ml). Two compounds were isolated and when compared with data from the literature; the structures were suggestive of polyphenolic flavonoid, quercetin and 3-O-β-D-glucopyranosyl-sitosterol. The result indicates that H. bonariensis leaves contain bioactive compounds with antioxidant activity.Keywords: antioxidant, cataract, free radical, flavonoids, hydrocotyl bonariensis
Procedia PDF Downloads 2643115 Application of Electrochemical Impedance Spectroscopy to Monitor the Steel/Soil Interface During Cathodic Protection of Steel in Simulated Soil Solution
Authors: Mandlenkosi George Robert Mahlobo, Tumelo Seadira, Major Melusi Mabuza, Peter Apata Olubambi
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Cathodic protection (CP) has been widely considered a suitable technique for mitigating corrosion of buried metal structures. Plenty of efforts have been made in developing techniques, in particular non-destructive techniques, for monitoring and quantifying the effectiveness of CP to ensure the sustainability and performance of buried steel structures. The aim of this study was to investigate the evolution of the electrochemical processes at the steel/soil interface during the application of CP on steel in simulated soil. Carbon steel was subjected to electrochemical tests with NS4 solution used as simulated soil conditions for 4 days before applying CP for a further 11 days. A previously modified non-destructive voltammetry technique was applied before and after the application of CP to measure the corrosion rate. Electrochemical impedance spectroscopy (EIS), in combination with mathematical modeling through equivalent electric circuits, was applied to determine the electrochemical behavior at the steel/soil interface. The measured corrosion rate was found to have decreased from 410 µm/yr to 8 µm/yr between days 5 and 14 because of the applied CP. Equivalent electrical circuits were successfully constructed and used to adequately model the EIS results. The modeling of the obtained EIS results revealed the formation of corrosion products via a mixed activation-diffusion mechanism during the first 4 days, while the activation mechanism prevailed in the presence of CP, resulting in a protective film. The x-ray diffraction analysis confirmed the presence of corrosion products and the predominant protective film corresponding to the calcareous deposit.Keywords: carbon steel, cathodic protection, NS4 solution, voltammetry, EIS
Procedia PDF Downloads 563114 The Effect of Corporate Governance to Islamic Banking Performance Using Maqasid Index Approach in Indonesia
Authors: Audia Syafa'atur Rahman, Rozali Haron
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The practices of Islamic banking are more attuned to the goals of profit maximization rather than obtaining ethical profit. Ethical profit is obtained from interest-free earnings and to give an impact which benefits to the growth of society and economy. Good corporate governance practices are needed to assure the sustainability of Islamic banks in order to achieve Maqasid Shariah with the main purpose of boosting the well-being of people. The Maqasid Shariah performance measurement is used to measure the duties and responsibilities expected to be performed by Islamic banks. It covers not only unification dimension like financial measurement, but also many dimensions covered to reflect the main purpose of Islamic banks. The implementation of good corporate governance is essential because it covers the interests of the stakeholders and facilitates effective monitoring to encourage Islamic banks to utilize resources more efficiently in order to achieve the Maqasid Shariah. This study aims to provide the empirical evidence on the Maqasid performance of Islamic banks in relation to the Maqasid performance evaluation model, to examine the influence of SSB characteristics and board structures to Islamic Banks performance as measured by Maqasid performance evaluation model. By employing the simple additive weighting method, Maqasid index for all the Islamic Banks in Indonesia within 2012 to 2016 ranged from above 11% to 28%. The Maqasid Syariah performance index where results reached above 20% are obtained by Islamic Banks such as Bank Muamalat Indonesia, Bank Panin Syariah, and Bank BRI Syariah. The consistent achievement above 23% is achieved by BMI. Other Islamic Banks such as Bank Victoria Syariah, Bank Jabar Banten Syariah, Bank BNI Syariah, Bank Mega Syariah, BCA Syariah, and Maybank Syariah Indonesia shows a fluctuating value of the Maqasid performance index every year. The impact of SSB characteristics and board structures are tested using random-effects generalized least square. The findings indicate that SSB characteristics (Shariah Supervisory Board size, Shariah Supervisory Board cross membership, Shariah Supervisory Board Education, and Shariah Supervisory Board reputation) and board structures (Board size and Board independence) have an essential role in improving the performance of Islamic Banks. The findings denote Shariah Supervisory Board with smaller size, higher portion of Shariah Supervisory Board cross membership; lesser Shariah Supervisory Board holds doctorate degree, lesser reputable scholar, more members on board of directors, and less independence non-executive directors will enhance the performance of Islamic Banks.Keywords: Maqasid Shariah, corporate governance, Islamic banks, Shariah supervisory board
Procedia PDF Downloads 2323113 Association Between Grandchild Caring With Different Household Structures and Depression at Later Life: A Cross-Sectional Study in India
Authors: Papai Barman, Harihar Sahoo
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With increasing life expectancy, urbanization, and adult out migration, elder people live without adult child and most of time responsible for grandchild caring while the care is needed for them. On this line, the current study examined the association between grandchild caring (GCC) with different household structures and depression among elderly (60+) grandparents (GP) living in India using Longitudinal Aging Study in India (LASI), 2017-18. HH structure was defined as the skipped-generation household (SGH) where GP and GC lived together without middle generation and the multi-generation household (MGH) where more than two generations lived together. GCC was defined by two categories, compulsive and non-compulsive caring. CES-D depression scale was utilized to measure GP’s mental health. Socio-economic characteristics, chronic diseases, and health behavior were controlled to get the effect of HH structure and GCC considered key explanatory variables. Bivariate analyses showed that the prevalence of elderly lived in SGH in India (2.5%). Prevalence of compulsive caring was found 16.3% in MGH and 51.1% in SGH. Prevalence of depressions was found nearly 37.1 and 49.5% among the GPs responsible for GCC in MGH and SGH, respectively. Using Biprobit and margins results, GPs lived in SGH were 0.40 times (dy/dx=0.40, p<0.001) more likely to report depression than GPs lived in MGH, given the condition on compulsive caring. Ensuring SDG goal-3, health aging, and giving more social security to the elder people responsible for caring while they are needed care at later life, the current study may improve the existing knowledge and help policy makers to make an intervention on this most vulnerable people, especially for the elderly people living in SGH and responsible for caring.Keywords: household structure, grandchild caring, skipped-generation household, multi-generation household, depression, mental health, India
Procedia PDF Downloads 683112 The Influence of Architectural-Planning Structure of Cities on Their Sustainable Development
Authors: M. Kashiripoor
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Existing indicators for sustainable urban development do not identify the features of cities’ planning structures and their architecture. Iranian city has special relevance problem of assessing the conformity of their planning and development of the concept of sustainable development. Based on theoretical sources, the author concludes that, despite the existence of common indicators for sustainable development of settlements, specialized evaluation criteria city structure planning has not been developed. He is trying to fill this gap and put forward a system of indicators characterizing the level of development of the architectural-planning structure of the city. The proposed system of indicators is designed based on technical and economic urban standard indicators from different countries. Alternative designing systems and requirements of modern rating systems like LEED-ND comprise a criterion for evaluation of urban structures in accordance with principles of "Green" building and New Urbanism. Urban development trends are close in spirit of sustainable development and developed under its influence. The study allowed concluding that a system of indicators to identify the relevant architectural-planning structure of the city, requirements of sustainable development, should be adapted to the conditions of each country, particularly in Iran. The article attempts typology proposed indicators, which are presented in tabular form and are divided into two types: planning and spatial. This article discusses the known indicators of sustainable development and proposed specific system of indicators characterizing the level of development of architectural-planning structure of the city. This article examines indicators for evaluating level of city' planning structure development. The proposed system of indicators is derived from the urban planning standards and rating systems such as LEED-ND, BREEAM Community and CASBEE-UD.Keywords: architectural-planning structure of cities, urban planning indicators, urban space indicators, urban development
Procedia PDF Downloads 6253111 Municipalities as Enablers of Citizen-Led Urban Initiatives: Possibilities and Constraints
Authors: Rosa Nadine Danenberg
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In recent years, bottom-up urban development has started growing as an alternative to conventional top-down planning. In large proportions, citizens and communities initiate small-scale interventions; suddenly seeming to form a trend. As a result, more and more cities are witnessing not only the growth of but also an interest in these initiatives, as they bear the potential to reshape urban spaces. Such alternative city-making efforts cause new dynamics in urban governance, with inevitable consequences for the controlled city planning and its administration. The emergence of enabling relationships between top-down and bottom-up actors signals an increasingly common urban practice. Various case studies show that an enabling relationship is possible, yet, how it can be optimally realized stays rather underexamined. Therefore, the seemingly growing worldwide phenomenon of ‘municipal bottom-up urban development’ necessitates an adequate governance structure. As such, the aim of this research is to contribute knowledge to how municipalities can enable citizen-led urban initiatives from a governance innovation perspective. Empirical case-study research in Stockholm and Istanbul, derived from interviews with founders of four citizen-led urban initiatives and one municipal representative in each city, provided valuable insights to possibilities and constraints for enabling practices. On the one hand, diverging outcomes emphasize the extreme oppositional features of both cases (Stockholm and Istanbul). Firstly, both cities’ characteristics are drastically different. Secondly, the ideologies and motifs for the initiatives to emerge vary widely. Thirdly, the major constraints for citizen-led urban initiatives to relate to the municipality are considerably different. Two types of municipality’s organizational structures produce different underlying mechanisms which demonstrate the constraints. The first municipal organizational structure is steered by bureaucracy (Stockholm). It produces an administrative division that brings up constraints such as the lack of responsibility, transparency and continuity by municipal representatives. The second structure is dominated by municipal politics and governmental hierarchy (Istanbul). It produces informality, lack of transparency and a fragmented civil society. In order to cope with the constraints produced by both types of organizational structures, the initiatives have adjusted their organization to the municipality’s underlying structures. On the other hand, this paper has in fact also come to a rather unifying conclusion. Interestingly, the suggested possibilities for an enabling relationship underline converging new urban governance arrangements. This could imply that for the two varying types of municipality’s organizational structures there is an accurate governance structure. Namely, the combination of a neighborhood council with a municipal guide, with allowance for the initiatives to adopt a politicizing attitude is found as coinciding. Especially its combination appears key to redeem varying constraints. A municipal guide steers the initiatives through bureaucratic struggles, is supported by coproduction methods, while it balances out municipal politics. Next, a neighborhood council, that is politically neutral and run by local citizens, can function as an umbrella for citizen-led urban initiatives. What is crucial is that it should cater for a more entangled relationship between municipalities and initiatives with enhanced involvement of the initiatives in decision-making processes and limited involvement of prevailing constraints pointed out in this research.Keywords: bottom-up urban development, governance innovation, Istanbul, Stockholm
Procedia PDF Downloads 2143110 Reservoir Potential, Net Pay Zone and 3D Modeling of Cretaceous Clastic Reservoir in Eastern Sulieman Belt Pakistan
Authors: Hadayat Ullah, Pervez Khalid, Saad Ahmed Mashwani, Zaheer Abbasi, Mubashir Mehmood, Muhammad Jahangir, Ehsan ul Haq
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The aim of the study is to explore subsurface structures through data that is acquired from the seismic survey to delineate the characteristics of the reservoir through petrophysical analysis. Ghazij Shale of Eocene age is regional seal rock in this field. In this research work, 3D property models of subsurface were prepared by applying Petrel software to identify various lithologies and reservoir fluids distribution throughout the field. The 3D static modeling shows a better distribution of the discrete and continuous properties in the field. This model helped to understand the reservoir properties and enhance production by selecting the best location for future drilling. A complete workflow is proposed for formation evaluation, electrofacies modeling, and structural interpretation of the subsurface geology. Based on the wireline logs, it is interpreted that the thickness of the Pab Sandstone varies from 250 m to 350 m in the entire study area. The sandstone is massive with high porosity and intercalated layers of shales. Faulted anticlinal structures are present in the study area, which are favorable for the accumulation of hydrocarbon. 3D structural models and various seismic attribute models were prepared to analyze the reservoir character of this clastic reservoir. Based on wireline logs and seismic data, clean sand, shaly sand, and shale are marked as dominant facies in the study area. However, clean sand facies are more favorable to act as a potential net pay zone.Keywords: cretaceous, pab sandstone, petrophysics, electrofacies, hydrocarbon
Procedia PDF Downloads 1363109 Optimum Design for Cathode Microstructure of Solid Oxide Fuel Cell
Authors: M. Riazat, H. Abdolvand, M. Baniassadi
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In this present work, 3D reconstruction of cathode of SOFC is developed with various volume fractions and porosity. Three Phase Boundary (TPB) of construction of such derived micro structures is calculated. The neural network is used to optimize the porosity and volume fraction of each phase to reach a structure with maximum TPB.Keywords: fuel cell, solid oxide, TPB, 3D reconstruction
Procedia PDF Downloads 3173108 Application of Micro-Tunneling Technique to Rectify Tilted Structures Constructed on Cohesive Soil
Authors: Yasser R. Tawfic, Mohamed A. Eid
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Foundation differential settlement and supported structure tilting is an occasionally occurred engineering problem. This may be caused by overloading, changes in ground soil properties or unsupported nearby excavations. Engineering thinking points directly toward the logic solution for such problem by uplifting the settled side. This can be achieved with deep foundation elements such as micro-piles and macro-piles™, jacked piers and helical piers, jet grouted soil-crete columns, compaction grout columns, cement grouting or with chemical grouting, or traditional pit underpinning with concrete and mortar. Although, some of these techniques offer economic, fast and low noise solutions, many of them are quite the contrary. For tilted structures, with limited inclination, it may be much easier to cause a balancing settlement on the less-settlement side which shall be done carefully in a proper rate. This principal has been applied in Leaning Tower of Pisa stabilization with soil extraction from the ground surface. In this research, the authors attempt to introduce a new solution with a different point of view. So, micro-tunneling technique is presented in here as an intended ground deformation cause. In general, micro-tunneling is expected to induce limited ground deformations. Thus, the researchers propose to apply the technique to form small size ground unsupported holes to produce the target deformations. This shall be done in four phases: •Application of one or more micro-tunnels, regarding the existing differential settlement value, under the raised side of the tilted structure. •For each individual tunnel, the lining shall be pulled out from both sides (from jacking and receiving shafts) in slow rate. •If required, according to calculations and site records, an additional surface load can be applied on the raised foundation side. •Finally, a strengthening soil grouting shall be applied for stabilization after adjustment. A finite element based numerical model is presented to simulate the proposed construction phases for different tunneling positions and tunnels group. For each case, the surface settlements are calculated and induced plasticity points are checked. These results show the impact of the suggested procedure on the tilted structure and its feasibility. Comparing results also show the importance of the position selection and tunnels group gradual effect. Thus, a new engineering solution is presented to one of the structural and geotechnical engineering challenges.Keywords: differential settlement, micro-tunneling, soil-structure interaction, tilted structures
Procedia PDF Downloads 1993107 Evaluation of the Mechanical Behavior of a Retaining Wall Structure on a Weathered Soil through Probabilistic Methods
Authors: P. V. S. Mascarenhas, B. C. P. Albuquerque, D. J. F. Campos, L. L. Almeida, V. R. Domingues, L. C. S. M. Ozelim
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Retaining slope structures are increasingly considered in geotechnical engineering projects due to extensive urban cities growth. These kinds of engineering constructions may present instabilities over the time and may require reinforcement or even rebuilding of the structure. In this context, statistical analysis is an important tool for decision making regarding retaining structures. This study approaches the failure probability of the construction of a retaining wall over the debris of an old and collapsed one. The new solution’s extension length will be of approximately 350 m and will be located over the margins of the Lake Paranoá, Brasilia, in the capital of Brazil. The building process must also account for the utilization of the ruins as a caisson. A series of in situ and laboratory experiments defined local soil strength parameters. A Standard Penetration Test (SPT) defined the in situ soil stratigraphy. Also, the parameters obtained were verified using soil data from a collection of masters and doctoral works from the University of Brasília, which is similar to the local soil. Initial studies show that the concrete wall is the proper solution for this case, taking into account the technical, economic and deterministic analysis. On the other hand, in order to better analyze the statistical significance of the factor-of-safety factors obtained, a Monte Carlo analysis was performed for the concrete wall and two more initial solutions. A comparison between the statistical and risk results generated for the different solutions indicated that a Gabion solution would better fit the financial and technical feasibility of the project.Keywords: economical analysis, probability of failure, retaining walls, statistical analysis
Procedia PDF Downloads 4023106 A Qualitative Inquiry of Institutional Responsiveness in Public Land Development in the Urban Areas in Sri Lanka
Authors: Priyanwada I. Singhapathirana
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The public land ownership is a common phenomenon in many countries in the world however, the development approaches and the institutional structures are greatly diverse. The existing scholarship around public land development has been greatly limited to Europe and advanced Asian economies. Inferences of such studies seem to be inadequate and inappropriate to comprehend the peculiarities of public land development in developing Asian economies. The absence of critical inquiry on the public land ownership and the long-established institutional structures which govern the development has restrained these countries from institutional innovations. In this context, this research investigates the issues related to public land development and the institutional responses in Sri Lanka. This study introduces the concept of ‘Institutional Responsiveness’ in Public land development, which is conceptualized as the ability of the institutions to respond to the spatial, market and fiscal stimulus. The inquiry was carried out through in-depth interviews with five key informants from apex public agencies in order to explore the responsiveness of land institutions form decision-makers' perspectives. Further, the analysis of grey literature and recent media reports are used to supplement the analysis. As per the findings, long term abandonment of public lands and high transaction costs are some of the key issues in relation to public land development. The inability of the institutions to respond to the market and fiscal stimulus has left many potential public lands underutilized. As a result, the public sector itself and urban citizens have not been able to relish the benefits of the public lands in cities. Spatial analysis at the local scale is suggested for future studies in order to capture the multiple dimensions of the responsiveness of institutions to the development stimulus.Keywords: institutions, public land, responsiveness, under-utilization
Procedia PDF Downloads 1233105 Analysis of Rockfall Hazard along Himalayan Road Cut Slopes
Authors: Sarada Prasad Pradhan, Vikram Vishal, Tariq Siddique
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With a vast area of India comprising of hilly terrain and road cut slopes, landslides and rockfalls are a common phenomenon. However, while landslide studies have received much attention in the past in India, very little literature and analysis is available regarding rockfall hazard of many rockfall prone areas, specifically in Uttarakhand Himalaya, India. The subsequent lack of knowledge and understanding of the rockfall phenomenon as well as frequent incidences of rockfall led fatalities urge the necessity of conducting site-specific rockfall studies to highlight the importance of addressing this issue as well as to provide data for safe design of preventive structures. The present study has been conducted across 10 rockfall prone road cut slopes for a distance of 15 km starting from Devprayag, India along National Highway 58 (NH-58). In order to make a qualitative assessment of Rockfall Hazard posed by these slopes, Rockfall Hazard Rating using standards for Indian Rockmass has been conducted at 10 locations under different slope conditions. Moreover, to accurately predict the characteristics of the possible rockfall phenomenon, numerical simulation was carried out to calculate the maximum bounce heights, total kinetic energies, translational velocities and trajectories of the falling rockmass blocks when simulated on each of these slopes according to real-life conditions. As it was observed that varying slope geometry had more fatal impacts on Rockfall hazard than size of rock masses, several optimizations have been suggested for each slope regarding location of barriers and modification of slope geometries in order to minimize damage by falling rocks. This study can be extremely useful in emphasizing the significance of rockfall studies and construction of mitigative barriers and structures along NH-58 around Devprayag.Keywords: rockfall, slope stability, rockmass, hazard
Procedia PDF Downloads 2073104 Temporal and Spacial Adaptation Strategies in Aerodynamic Simulation of Bluff Bodies Using Vortex Particle Methods
Authors: Dario Milani, Guido Morgenthal
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Fluid dynamic computation of wind caused forces on bluff bodies e.g light flexible civil structures or high incidence of ground approaching airplane wings, is one of the major criteria governing their design. For such structures a significant dynamic response may result, requiring the usage of small scale devices as guide-vanes in bridge design to control these effects. The focus of this paper is on the numerical simulation of the bluff body problem involving multiscale phenomena induced by small scale devices. One of the solution methods for the CFD simulation that is relatively successful in this class of applications is the Vortex Particle Method (VPM). The method is based on a grid free Lagrangian formulation of the Navier-Stokes equations, where the velocity field is modeled by particles representing local vorticity. These vortices are being convected due to the free stream velocity as well as diffused. This representation yields the main advantages of low numerical diffusion, compact discretization as the vorticity is strongly localized, implicitly accounting for the free-space boundary conditions typical for this class of FSI problems, and a natural representation of the vortex creation process inherent in bluff body flows. When the particle resolution reaches the Kolmogorov dissipation length, the method becomes a Direct Numerical Simulation (DNS). However, it is crucial to note that any solution method aims at balancing the computational cost against the accuracy achievable. In the classical VPM method, if the fluid domain is discretized by Np particles, the computational cost is O(Np2). For the coupled FSI problem of interest, for example large structures such as long-span bridges, the aerodynamic behavior may be influenced or even dominated by small structural details such as barriers, handrails or fairings. For such geometrically complex and dimensionally large structures, resolving the complete domain with the conventional VPM particle discretization might become prohibitively expensive to compute even for moderate numbers of particles. It is possible to reduce this cost either by reducing the number of particles or by controlling its local distribution. It is also possible to increase the accuracy of the solution without increasing substantially the global computational cost by computing a correction of the particle-particle interaction in some regions of interest. In this paper different strategies are presented in order to extend the conventional VPM method to reduce the computational cost whilst resolving the required details of the flow. The methods include temporal sub stepping to increase the accuracy of the particles convection in certain regions as well as dynamically re-discretizing the particle map to locally control the global and the local amount of particles. Finally, these methods will be applied on a test case and the improvements in the efficiency as well as the accuracy of the proposed extension to the method are presented. The important benefits in terms of accuracy and computational cost of the combination of these methods will be thus presented as long as their relevant applications.Keywords: adaptation, fluid dynamic, remeshing, substepping, vortex particle method
Procedia PDF Downloads 2553103 Role of Speech Articulation in English Language Learning
Authors: Khadija Rafi, Neha Jamil, Laiba Khalid, Meerub Nawaz, Mahwish Farooq
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Speech articulation is a complex process to produce intelligible sounds with the help of precise movements of various structures within the vocal tract. All these structures in the vocal tract are named as articulators, which comprise lips, teeth, tongue, and palate. These articulators work together to produce a range of distinct phonemes, which happen to be the basis of language. It starts with the airstream from the lungs passing through the trachea and into oral and nasal cavities. When the air passes through the mouth, the tongue and the muscles around it form such coordination it creates certain sounds. It can be seen when the tongue is placed in different positions- sometimes near the alveolar ridge, soft palate, roof of the mouth or the back of the teeth which end up creating unique qualities of each phoneme. We can articulate vowels with open vocal tracts, but the height and position of the tongue is different every time depending upon each vowel, while consonants can be pronounced when we create obstructions in the airflow. For instance, the alphabet ‘b’ is a plosive and can be produced only by briefly closing the lips. Articulation disorders can not only affect communication but can also be a hurdle in speech production. To improve articulation skills for such individuals, doctors often recommend speech therapy, which involves various kinds of exercises like jaw exercises and tongue twisters. However, this disorder is more common in children who are going through developmental articulation issues right after birth, but in adults, it can be caused by injury, neurological conditions, or other speech-related disorders. In short, speech articulation is an essential aspect of productive communication, which also includes coordination of the specific articulators to produce different intelligible sounds, which are a vital part of spoken language.Keywords: linguistics, speech articulation, speech therapy, language learning
Procedia PDF Downloads 573102 Optical Breather in Phosphorene Monolayer
Authors: Guram Adamashvili
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Surface plasmon polariton is a surface optical wave which undergoes a strong enhancement and spatial confinement of its wave amplitude near an interface of two-dimensional layered structures. Phosphorene (single-layer black phosphorus) and other two-dimensional anisotropic phosphorene-like materials are recognized as promising materials for potential future applications of surface plasmon polariton. A theory of an optical breather of self-induced transparency for surface plasmon polariton propagating in monolayer or few-layer phosphorene is developed. A theory of an optical soliton of self-induced transparency for surface plasmon polariton propagating in monolayer or few-layer phosphorene have been investigated earlier Starting from the optical nonlinear wave equation for surface TM-modes interacting with a two-dimensional layer of atomic systems or semiconductor quantum dots and a phosphorene monolayer (or other two-dimensional anisotropic material), we have obtained the evolution equations for the electric field of the breather. In this case, one finds that the evolution of these pulses become described by the damped Bloch-Maxwell equations. For surface plasmon polariton fields, breathers are found to occur. Explicit relations of the dependence of breathers on the local media, phosphorene anisotropic conductivity, transition layer properties and transverse structures of the SPP, are obtained and will be given. It is shown that the phosphorene conductivity reduces exponentially the amplitude of the surface breather of SIT in the process of propagation. The direction of propagation corresponding to the maximum and minimum damping of the amplitude are assigned along the armchair and zigzag directions of black phosphorus nano-film, respectively. The most rapid damping of the intensity occurs when the polarization of breather is along the armchair direction.Keywords: breathers, nonlinear waves, solitons, surface plasmon polaritons
Procedia PDF Downloads 1413101 Numerical Study of Elastic Performances of Sandwich Beam with Carbon-Fibre Reinforced Skins
Authors: Soukaina Ounss, Hamid Mounir, Abdellatif El Marjani
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Sandwich materials with composite reinforced skins are mostly required in advanced construction applications with a view to ensure resistant structures. Their lightweight, their high flexural stiffness and their optimal thermal insulation make them a suitable solution to obtain efficient structures with performing rigidity and optimal energy safety. In this paper, the mechanical behavior of a sandwich beam with composite skins reinforced by unidirectional carbon fibers is investigated numerically through analyzing the impact of reinforcements specifications on the longitudinal elastic modulus in order to select the adequate sandwich configuration that has an interesting rigidity and an accurate convergence to the analytical approach which is proposed to verify performed numerical simulations. Therefore, concerned study starts by testing flexion performances of skins with various fibers orientations and volume fractions to determine those to use in sandwich beam. For that, the combination of a reinforcement inclination of 30° and a volume ratio of 60% is selected with the one with 60° of fibers orientation and 40% of volume fraction, this last guarantees to chosen skins an important rigidity with an optimal fibers concentration and a great enhance in convergence to analytical results in the sandwich model for the reason of the crucial core role as transverse shear absorber. Thus, a resistant sandwich beam is elaborated from a face-sheet constituted from two layers of previous skins with fibers oriented in 60° and an epoxy core; concerned beam has a longitudinal elastic modulus of 54 Gpa (gigapascal) that equals to the analytical value by a negligible error of 2%.Keywords: fibers orientation, fibers volume ratio, longitudinal elastic modulus, sandwich beam
Procedia PDF Downloads 1593100 Study of Ageing in the Marine Environment of Bonded Composite Structures by Ultrasonic Guided Waves. Comparison of the Case of a Conventional Carbon-epoxy Composite and a Recyclable Resin-Based Composite
Authors: Hamza Hafidi Alaoui, Damien Leduc, Mounsif Ech Cherif El Kettani
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This study is dedicated to the evaluation of the ageing of turbine blades in sea conditions, based on ultrasonic Non Destructive Testing (NDT) methods. This study is being developed within the framework of the European Interreg TIGER project. The Tidal Stream Industry Energiser Project, known as TIGER, is the biggest ever Interreg project driving collaboration and cost reductionthrough tidal turbine installations in the UK and France. The TIGER project will drive the growth of tidal stream energy to become a greater part of the energy mix, with significant benefits for coastal communities. In the bay of Paimpol-Bréhat (Brittany), different samples of composite material and bonded composite/composite structures have been immersed at the same time near a turbine. The studied samples are either conventional carbon-epoxy composite samples or composite samples based on a recyclable resin (called recyclamine). One of the objectives of the study is to compare the ageing of the two types of structure. A sample of each structure is picked up every 3 to 6 months and analyzed using ultrasonic guided waves and bulk waves and compared to reference samples. In order to classify the damage level as a function of time spent under the sea, the measure have been compared to a rheological model based on the Finite Elements Method (FEM). Ageing of the composite material, as well as that of the adhesive, is identified. The aim is to improve the quality of the turbine blade structure in terms of longevity and reduced maintenance needs.Keywords: non-destructive testing, ultrasound, composites, guides waves
Procedia PDF Downloads 2133099 Ground Response Analysis at the Rukni Irrigation Project Site Located in Assam, India
Authors: Tauhidur Rahman, Kasturi Bhuyan
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In the present paper, Ground Response Analysis at the Rukni irrigation project has been thoroughly investigated. Surface level seismic hazard is mainly used by the practical Engineers for designing the important structures. Surface level seismic hazard can be obtained accounting the soil factor. Structures on soft soil will show more ground shaking than the structure located on a hard soil. The Surface level ground motion depends on the type of soil. Density and shear wave velocity is different for different types of soil. The intensity of the soil amplification depends on the density and shear wave velocity of the soil. Rukni irrigation project is located in the North Eastern region of India, near the Dauki fault (550 Km length) which has already produced earthquakes of magnitude (Mw= 8.5) in the past. There is a probability of a similar type of earthquake occuring in the future. There are several faults also located around the project site. There are 765 recorded strong ground motion time histories available for the region. These data are used to determine the soil amplification factor by incorporation of the engineering properties of soil. With this in view, three of soil bore holes have been studied at the project site up to a depth of 30 m. It has been observed that in Soil bore hole 1, the shear wave velocity vary from 99.44 m/s to 239.28 m/s. For Soil Bore Hole No 2 and 3, shear wave velocity vary from 93.24 m/s to 241.39 m/s and 93.24m/s to 243.01 m/s. In the present work, surface level seismic hazard at the project site has been calculated based on the Probabilistic seismic hazard approach accounting the soil factor.Keywords: Ground Response Analysis, shear wave velocity, soil amplification, surface level seismic hazard
Procedia PDF Downloads 5473098 Human and Environment Coevolution: The Chalcolithic Tell Settlements from Muntenia and Dobrogea, South-Eastern Romania
Authors: Constantin Haita
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The chalcolithic tell settlements from south-eastern Romania, attributed to Gumelnița culture, are characterised by a well-defined surface, marked often by delimitation structures, a succession of many layers of construction, destruction, and rebuilding, and a well-structured area of occupation: built spaces, passage areas, waste zones. Settlements of tell type are located in the river valleys –on erosion remnants, alluvial bars or small islands, at the border of the valleys– on edges or prominences of Pleistocene terraces, lower Holocene terraces, and banks of lakes. This study integrates data on the geographical position, the morphological background, and the general stratigraphy of these important settlements. The correlation of the spatial distribution with the geomorphological units of each area of evolution creates an image of the natural landscape in which they occurred. The sedimentological researches achieved in the floodplain area of Balta Ialomiței showed important changes in the alluvial activity of Danube, after the Chalcolithic period (ca. 6500 - 6000 BP), to Iron Age and Middle Ages. The micromorphological analysis, consisting in thin section interpretation, at the microscopic scale, of sediments and soils in an undisturbed state, allowed the interpretation of the identified sedimentary facies, in terms of mode of formation and anthropic activities. Our studied cases reflect some distinct situations, correlating either with the geomorphological background or with the vertical development, the presence of delimiting structures and the internal organization. The characteristics of tells from this area bring significant information about the human habitation of Lower Danube in Prehistory.Keywords: chalcolithic, micromorphology, Romania, sedimentology, tell settlements
Procedia PDF Downloads 1443097 In Situ Volume Imaging of Cleared Mice Seminiferous Tubules Opens New Window to Study Spermatogenic Process in 3D
Authors: Lukas Ded
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Studying the tissue structure and histogenesis in the natural, 3D context is challenging but highly beneficial process. Contrary to classical approach of the physical tissue sectioning and subsequent imaging, it enables to study the relationships of individual cellular and histological structures in their native context. Recent developments in the tissue clearing approaches and microscopic volume imaging/data processing enable the application of these methods also in the areas of developmental and reproductive biology. Here, using the CLARITY tissue procedure and 3D confocal volume imaging we optimized the protocol for clearing, staining and imaging of the mice seminiferous tubules isolated from the testes without cardiac perfusion procedure. Our approach enables the high magnification and fine resolution axial imaging of the whole diameter of the seminiferous tubules with possible unlimited lateral length imaging. Hence, the large continuous pieces of the seminiferous tubule can be scanned and digitally reconstructed for the study of the single tubule seminiferous stages using nuclear dyes. Furthermore, the application of the antibodies and various molecular dyes can be used for molecular labeling of individual cellular and subcellular structures and resulting 3D images can highly increase our understanding of the spatiotemporal aspects of the seminiferous tubules development and sperm ultrastructure formation. Finally, our newly developed algorithms for 3D data processing enable the massive parallel processing of the large amount of individual cell and tissue fluorescent signatures and building the robust spermatogenic models under physiological and pathological conditions.Keywords: CLARITY, spermatogenesis, testis, tissue clearing, volume imaging
Procedia PDF Downloads 1333096 Structural Fluxionality of Luminescent Coordination Compounds with Lanthanide Ions
Authors: Juliana A. B. Silva, Caio H. T. L. Albuquerque, Leonardo L. dos Santos, Cristiane K. Oliveira, Ivani Malvestiti, Fernando Hallwass, Ricardo L. Longo
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Complexes with lanthanide ions have been extensively studied due to their applications as luminescent, magnetic and catalytic materials as molecular or extended crystals, thin films, glasses, polymeric matrices, ionic liquids, and in solution. NMR chemical shift data in solution have been reported and suggest fluxional structures in a wide range of coordination compounds with rare earth ions. However, the fluxional mechanisms for these compounds are still not established. This structural fluxionality may affect the photophysical, catalytic and magnetic properties in solution. Thus, understanding the structural interconversion mechanisms may aid the design of coordination compounds with, for instance, improved (electro)luminescence, catalytic and magnetic behaviors. The [Eu(btfa)₃bipy] complex, where btfa= 4,4,4-trifluoro-1-phenyl-1,3-butanedionate and bipy= 2,2’-bipiridyl, has a well-defined X-ray crystallographic structure and preliminary 1H NMR data suggested a structural fluxionality. Thus, we have investigated a series of coordination compounds with lanthanide ions [Ln(btfa)₃L], where Ln = La, Eu, Gd or Yb and L= bipy or phen (phen=1,10-phenanthroline) using a combined theoretical-experimental approach. These complexes were synthesized and fully characterized, and detailed NMR measurements were obtained. They were also studied by quantum chemical computational methods (DFT-PBE0). The aim was to determine the relevant factors in the structure of these compounds that favor or not the fluxional behavior. Measurements of the 1H NMR signals at variable temperature in CD₂Cl₂ of the [Eu(btfa)₃L] complexes suggest that these compounds have a fluxional structure, because the crystal structure has non-equivalent btfa ligands that should lead to non-equivalent hydrogen atoms and thus to more signals in the NMR spectra than those obtained at room temperature, where all hydrogen atoms of the btfa ligands are equivalent, and phen ligand has an effective vertical symmetry plane. For the [Eu(btfa)₃bipy] complex, the broadening of the signals at –70°C provides a lower bound for the coalescence temperature, which indicates the energy barriers involved in the structural interconversion mechanisms are quite small. These barriers and, consequently, the coalescence temperature are dependent upon the radii of the lanthanide ion as well as to their paramagnetic effects. The PBE0 calculated structures are in very good agreement with the crystallographic data and, for the [Eu(btfa)₃bipy] complex, this method provided several distinct structures with almost the same energy. However, the energy barrier for structural interconversion via dissociative pathways were found to be quite high and could not explain the experimental observations. Whereas the pseudo-rotation pathways, involving the btfa and bipy ligands, have very small activation barriers, in excellent agreement with the NMR data. The results also showed an increase in the activation barrier along the lanthanide series due to the decrease of the ionic radii and consequent increase of the steric effects. TD-DFT calculations showed a dependence of the ligand donor state energy with different structures of the complex [Eu(btfa)₃phen], which can affect the energy transfer rates and the luminescence. The energy required to promote the structural fluxionality may also enhance the luminescence quenching in solution. These results can aid in the design of more luminescent compounds and more efficient devices.Keywords: computational chemistry, lanthanide-based compounds, NMR, structural fluxionality
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