Search results for: energy distribution
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 12542

Search results for: energy distribution

2162 Development of Fault Diagnosis Technology for Power System Based on Smart Meter

Authors: Chih-Chieh Yang, Chung-Neng Huang

Abstract:

In power system, how to improve the fault diagnosis technology of transmission line has always been the primary goal of power grid operators. In recent years, due to the rise of green energy, the addition of all kinds of distributed power also has an impact on the stability of the power system. Because the smart meters are with the function of data recording and bidirectional transmission, the adaptive Fuzzy Neural inference system, ANFIS, as well as the artificial intelligence that has the characteristics of learning and estimation in artificial intelligence. For transmission network, in order to avoid misjudgment of the fault type and location due to the input of these unstable power sources, combined with the above advantages of smart meter and ANFIS, a method for identifying fault types and location of faults is proposed in this study. In ANFIS training, the bus voltage and current information collected by smart meters can be trained through the ANFIS tool in MATLAB to generate fault codes to identify different types of faults and the location of faults. In addition, due to the uncertainty of distributed generation, a wind power system is added to the transmission network to verify the diagnosis correctness of the study. Simulation results show that the method proposed in this study can correctly identify the fault type and location of fault with more efficiency, and can deal with the interference caused by the addition of unstable power sources.

Keywords: ANFIS, fault diagnosis, power system, smart meter

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2161 Investigation of Polymer Solar Cells Degradation Behavior Using High Defect States Influence Over Various Polymer Absorber Layers

Authors: Azzeddine Abdelalim, Fatiha Rogti

Abstract:

The degradation phenomenon in polymer solar cells (PCSs) has not been clearly explained yet. In fact, there are many causes that show up and influence these cells in a variety of ways. Also, there has been a growing concern over this degradation in the photovoltaic community. One of the main variables deciding PSCs photovoltaic output is defect states. In this research, devices modeling is carried out to analyze the multiple effects of degradation by applying high defect states (HDS) on ideal PSCs, mainly poly(3-hexylthiophene) (P3HT) absorber layer. Besides, a comparative study is conducted between P3HT and other PSCs by a simulation program called Solar Cell Capacitance Simulator (SCAPS). The adjustments to the defect parameters in several absorber layers explain the effect of HDS on the total output properties of PSCs. The performance parameters for HDS, quantum efficiency, and energy band were therefore examined. This research attempts to explain the degradation process of PSCs and the causes of their low efficiency. It was found that the defects often affect PSCs performance, but defect states have a little effect on output when the defect level is less than 1014cm-3, which gives similar performance values with P3HT cells when these defects is about 1019cm-3. The high defect states can cause up to 11% relative reduction in conversion efficiency of ideal P3HT. In the center of the band gap, defect states become more noxious. This approach is for one of the degradation processes potential of PSCs especially that use fullerene derivative acceptors.

Keywords: degradation, high defect states, polymer solar cells, SCAPS-1D

Procedia PDF Downloads 85
2160 The Importance of Efficient and Sustainable Water Resources Management and the Role of Artificial Intelligence in Preventing Forced Migration

Authors: Fateme Aysin Anka, Farzad Kiani

Abstract:

Forced migration is a situation in which people are forced to leave their homes against their will due to political conflicts, wars and conflicts, natural disasters, climate change, economic crises, or other emergencies. This type of migration takes place under conditions where people cannot lead a sustainable life due to reasons such as security, shelter and meeting their basic needs. This type of migration may occur in connection with different factors that affect people's living conditions. In addition to these general and widespread reasons, water security and resources will be one that is starting now and will be encountered more and more in the future. Forced migration may occur due to insufficient or depleted water resources in the areas where people live. In this case, people's living conditions become unsustainable, and they may have to go elsewhere, as they cannot obtain their basic needs, such as drinking water, water used for agriculture and industry. To cope with these situations, it is important to minimize the causes, as international organizations and societies must provide assistance (for example, humanitarian aid, shelter, medical support and education) and protection to address (or mitigate) this problem. From the international perspective, plans such as the Green New Deal (GND) and the European Green Deal (EGD) draw attention to the need for people to live equally in a cleaner and greener world. Especially recently, with the advancement of technology, science and methods have become more efficient. In this regard, in this article, a multidisciplinary case model is presented by reinforcing the water problem with an engineering approach within the framework of the social dimension. It is worth emphasizing that this problem is largely linked to climate change and the lack of a sustainable water management perspective. As a matter of fact, the United Nations Development Agency (UNDA) draws attention to this problem in its universally accepted sustainable development goals. Therefore, an artificial intelligence-based approach has been applied to solve this problem by focusing on the water management problem. The most general but also important aspect in the management of water resources is its correct consumption. In this context, the artificial intelligence-based system undertakes tasks such as water demand forecasting and distribution management, emergency and crisis management, water pollution detection and prevention, and maintenance and repair control and forecasting.

Keywords: water resource management, forced migration, multidisciplinary studies, artificial intelligence

Procedia PDF Downloads 79
2159 Tribological Response of Self-Mated Zircaloy-4 under Varying Conditions

Authors: Bharat Kumar, Deepak Kumar, Vijay Chaudhry

Abstract:

Zirconium alloys are widely used for the core components of a pressurized heavy water reactor (PHWR) or Canada deuterium (CANDU) reactor due to their low neutron absorption cross-section and excellent mechanical properties. The components made of Zirconium alloys are subjected to flow-induced vibrations, resulting in fretting wear at the interface of; pressure tubes and bearing pads, pressure tubes and calandria tubes, and calandria tubes and Liquid injection shutdown system (LISS) nozzles. There is a need to explore the tribological response under such conditions. Present work simulates the contact between calandria tube and LISS nozzle of PHWR/CANDU reactor as cylinder-on-cylinder contact configuration. Reciprocating tribo-tests were conducted on Zircaloy-4 (Zr-4) under the self-mated condition at varying amplitude, frequency, and sliding time. To understand the active wear mechanism, worn surfaces were analyzed using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The change in amplitude severely affects the wear than other factors. The wear mechanism transits from adhesion to abrasion with increasing test amplitude. The dominant wear mechanisms are micro-cutting and micro-plowing followed by delamination in some areas. However, the coefficient of friction has indifferent behaviors.

Keywords: zircaloy-4, tribology, calandria tube, LISS nozzle, PHWR

Procedia PDF Downloads 197
2158 A Review on Application of Phase Change Materials in Textiles Finishing

Authors: Mazyar Ahrari, Ramin Khajavi, Mehdi Kamali Dolatabadi, Tayebeh Toliyat, Abosaeed Rashidi

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Fabric as the first and most common layer that is in permanent contact with human skin is a very good interface to provide coverage, as well as heat and cold insulation. Phase change materials (PCMs) are organic and inorganic compounds which have the capability of absorbing and releasing noticeable amounts of latent heat during phase transitions between solid and liquid phases at a low temperature range. PCMs come across phase changes (liquid-solid and solid-liquid transitions) during absorbing and releasing thermal heat; so, in order to use them for a long time, they should have been encapsulated in polymeric shells, so-called microcapsules. Microencapsulation and nanoencapsulation methods have been developed in order to reduce the reactivity of a PCM with outside environment, promoting the ease of handling, decreasing the diffusion and evaporation rates. Methods of incorporation of PCMs in textiles such as electrospinning and determining thermal properties had been summarized. Paraffin waxes catch a lot of attention due to their high thermal storage density, repeatability of phase change, thermal stability, small volume change during phase transition, chemical stability, non-toxicity, non-flammability, non-corrosive and low cost and they seem to play a key role in confronting with climate change and global warming. In this article, we aimed to review the researches concentrating on the characteristics of PCMs and new materials and methods of microencapsulation.

Keywords: thermoregulation, microencapsulation, phase change materials, thermal energy storage, nanoencapsulation

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2157 Coarse-Grained Molecular Simulations to Estimate Thermophysical Properties of Phase Equilibria

Authors: Hai Hoang, Thanh Xuan Nguyen Thi, Guillaume Galliero

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Coarse-Grained (CG) molecular simulations have shown to be an efficient way to estimate thermophysical (static and dynamic) properties of fluids. Several strategies have been developed and reported in the literature for defining CG molecular models. Among them, those based on a top-down strategy (i.e. CG molecular models related to macroscopic observables), despite being heuristic, have increasingly gained attention. This is probably due to its simplicity in implementation and its ability to provide reasonable results for not only simple but also complex systems. Regarding simple Force-Fields associated with these CG molecular models, it has been found that the four parameters Mie chain model is one of the best compromises to describe thermophysical static properties (e.g. phase diagram, saturation pressure). However, parameterization procedures of these Mie-chain GC molecular models given in literature are generally insufficient to simultaneously provide static and dynamic (e.g. viscosity) properties. To deal with such situations, we have extended the corresponding states by using a quantity associated with the liquid viscosity. Results obtained from molecular simulations have shown that our approach is able to yield good estimates for both static and dynamic thermophysical properties for various real non-associating fluids. In addition, we will show that on simple (e.g. phase diagram, saturation pressure) and complex (e.g. thermodynamic response functions, thermodynamic energy potentials) static properties, results of our scheme generally provides improved results compared to existing approaches.

Keywords: coarse-grained model, mie potential, molecular simulations, thermophysical properties, phase equilibria

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2156 Development of Value Added Product Based on Millets and Hemp Seed (cannabis sativa L.)

Authors: Khushi Kashyap, Pratibha Singh

Abstract:

In the recent years increasing interest in vegetarian diets has been observed, a major problem in this type of diet is to provide the appropriate amount of protein .Value addition of food is current most talked topic because of increasing nutritional awareness among consumers today. An investigation was conducted to develop protein rich multi-millet hemp seed khakhra. The seeds of cannabis sativa L. have been a significant source of food for thousand of year. In recent years, hemp has not been thoroughly explored for its nutritional potential due to the mistaken belief regarding the cannabis plants. Methodology- two variations was prepared referencing standard recipe. Variation 1 was prepared using 25g ragi, 25g bajra,40g whole wheat flour with 10g hemp seed powder, variation 2(RF-25g,BF25g,WWF-35g,HS-15g). The product was subjected to sensory evolution by semi trained panel members using 9 point hedonic on 50 panelists. Result- result of the sensory evaluation revealed that the product incorporated with 15g of hemp seed were similar to control I texture, taste and overall quality and was more acceptable by the panelist and was selected as final product seed. On estimation of the nutrient content 30g of khakhra provides 107kcal of energy,12g protein,75g carbohydrate, and 9.6g of fats with shelf life of 3 months. Conclusion- khakhras can be eaten as a snack at any time of the day. hemp seed powder incorporated in it enhances its nutritive value and makes it more nutritious. It is suitable for consumption of all the age group.

Keywords: cannabis sativa, hemp, protein, seed

Procedia PDF Downloads 79
2155 Tandem Concentrated Photovoltaic-Thermoelectric Hybrid System: Feasibility Analysis and Performance Enhancement Through Material Assessment Methodology

Authors: Shuwen Hu, Yuancheng Lou, Dongxu Ji

Abstract:

Photovoltaic (PV) power generation, as one of the most commercialized methods to utilize solar power, can only convert a limited range of solar spectrum into electricity, whereas the majority of the solar energy is dissipated as heat. To address this problem, thermoelectric (TE) module is often integrated with the concentrated PV module for waste heat recovery and regeneration. In this research, a feasibility analysis is conducted for the tandem concentrated photovoltaic-thermoelectric (CPV-TE) hybrid system considering various operational parameters as well as TE material properties. Furthermore, the power output density of the CPV-TE hybrid system is maximized by selecting the optimal TE material with application of a systematic assessment methodology. In the feasibility analysis, CPV-TE is found to be more advantageous than sole CPV system except under high optical concentration ratio with low cold side convective coefficient. It is also shown that the effects of the TE material properties, including Seebeck coefficient, thermal conductivity, and electrical resistivity, on the feasibility of CPV-TE are interacted with each other and might have opposite effect on the system performance under different operational conditions. In addition, the optimal TE material selected by the proposed assessment methodology can improve the system power output density by 227 W/m2 under highly concentrated solar irradiance hence broaden the feasible range of CPV-TE considering optical concentration ratio.

Keywords: feasibility analysis, material assessment methodology, photovoltaic waste heat recovery, tandem photovoltaic-thermoelectric

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2154 Experimental and Computational Investigations on the Mitigation of Air Pollutants Using Pulsed Radio Waves

Authors: Gangadhara Siva Naga Venkata Krishna Satya Narayana Swamy Undi

Abstract:

Particulate matter (PM) pollution in ambient air is a major environmental health risk factor contributing to disease and mortality worldwide. Current air pollution control methods have limitations in reducing real-world ambient PM levels. This study demonstrates the efficacy of using pulsed radio wave technology as a distinct approach to lower outdoor particulate pollution. Experimental data were compared with computational models to evaluate the efficiency of pulsed waves in coagulating and settling PM. Results showed 50%+ reductions in PM2.5 and PM10 concentrations at the city scale, with particle removal rates exceeding gravity settling by over 3X. Historical air quality data further validated the significant PM reductions achieved in test cases. Computational analyses revealed the underlying coagulation mechanisms induced by the pulsed waves, supporting the feasibility of this strategy for ambient particulate control. The pulsed electromagnetic technology displayed robustness in sustainably managing PM levels across diverse urban and industrial environments. Findings highlight the promise of this advanced approach as a next-generation solution to mitigate particulate air pollution and associated health burdens globally. The technology's scalability and energy efficiency can help address a key gap in current efforts to improve ambient air quality.

Keywords: particulate matter, mitigation technologies, clean air, ambient air pollution

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2153 Possibilities to Evaluate the Climatic and Meteorological Potential for Viticulture in Poland: The Case Study of the Jagiellonian University Vineyard

Authors: Oskar Sekowski

Abstract:

Current global warming causes changes in the traditional zones of viticulture worldwide. During 20th century, the average global air temperature increased by 0.89˚C. The models of climate change indicate that viticulture, currently concentrating in narrow geographic niches, may move towards the poles, to higher geographic latitudes. Global warming may cause changes in traditional viticulture regions. Therefore, there is a need to estimate the climatic conditions and climate change in areas that are not traditionally associated with viticulture, e.g., Poland. The primary objective of this paper is to prepare methodology to evaluate the climatic and meteorological potential for viticulture in Poland based on a case study. Moreover, the additional aim is to evaluate the climatic potential of a mesoregion where a university vineyard is located. The daily data of temperature, precipitation, insolation, and wind speed (1988-2018) from the meteorological station located in Łazy, southern Poland, was used to evaluate 15 climatological parameters and indices connected with viticulture. The next steps of the methodology are based on Geographic Information System methods. The topographical factors such as a slope gradient and slope exposure were created using Digital Elevation Models. The spatial distribution of climatological elements was interpolated by ordinary kriging. The values of each factor and indices were also ranked and classified. The viticultural potential was determined by integrating two suitability maps, i.e., the topographical and climatic ones, and by calculating the average for each pixel. Data analysis shows significant changes in heat accumulation indices that are driven by increases in maximum temperature, mostly increasing number of days with Tmax > 30˚C. The climatic conditions of this mesoregion are sufficient for vitis vinifera viticulture. The values of indicators and insolation are similar to those in the known wine regions located on similar geographical latitudes in Europe. The smallest threat to viticulture in study area is the occurrence of hail and the highest occurrence of frost in the winter. This research provides the basis for evaluating general suitability and climatologic potential for viticulture in Poland. To characterize the climatic potential for viticulture, it is necessary to assess the suitability of all climatological and topographical factors that can influence viticulture. The methodology used in this case study shows places where there is a possibility to create vineyards. It may also be helpful for wine-makers to select grape varieties.

Keywords: climatologic potential, climatic classification, Poland, viticulture

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2152 Demographic Shrinkage and Reshaping Regional Policy of Lithuania in Economic Geographic Context

Authors: Eduardas Spiriajevas

Abstract:

Since the end of the 20th century, when Lithuania regained its independence, a process of demographic shrinkage started. Recently, it affects the efficiency of implementation of actions related to regional development policy and geographic scopes of created value added in the regions. The demographic structures of human resources reflect onto the regions and their economic geographic environment. Due to reshaping economies and state reforms on restructuration of economic branches such as agriculture and industry, it affects the economic significance of services’ sector. These processes influence the competitiveness of labor market and its demographic characteristics. Such vivid consequences are appropriate for the structures of human migrations, which affected the processes of demographic ageing of human resources in the regions, especially in peripheral ones. These phenomena of modern times induce the demographic shrinkage of society and its economic geographic characteristics in the actions of regional development and in regional policy. The internal and external migrations of population captured numerous regional economic disparities, and influenced on territorial density and concentration of population of the country and created the economies of spatial unevenness in such small geographically compact country as Lithuania. The processes of territorial reshaping of distribution of population create new regions and their economic environment, which is not corresponding to the main principles of regional policy and its power to create the well-being and to promote the attractiveness for economic development. These are the new challenges of national regional policy and it should be researched in a systematic way of taking into consideration the analytical approaches of regional economy in the context of economic geographic research methods. A comparative territorial analysis according to administrative division of Lithuania in relation to retrospective approach and introduction of method of location quotients, both give the results of economic geographic character with cartographic representations using the tools of spatial analysis provided by technologies of Geographic Information Systems. A set of these research methods provide the new spatially evidenced based results, which must be taken into consideration in reshaping of national regional policy in economic geographic context. Due to demographic shrinkage and increasing differentiation of economic developments within the regions, an input of economic geographic dimension is inevitable. In order to sustain territorial balanced economic development, there is a need to strengthen the roles of regional centers (towns) and to empower them with new economic functionalities for revitalization of peripheral regions, and to increase their economic competitiveness and social capacities on national scale.

Keywords: demographic shrinkage, economic geography, Lithuania, regions

Procedia PDF Downloads 151
2151 An Eulerian Method for Fluid-Structure Interaction Simulation Applied to Wave Damping by Elastic Structures

Authors: Julien Deborde, Thomas Milcent, Stéphane Glockner, Pierre Lubin

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A fully Eulerian method is developed to solve the problem of fluid-elastic structure interactions based on a 1-fluid method. The interface between the fluid and the elastic structure is captured by a level set function, advected by the fluid velocity and solved with a WENO 5 scheme. The elastic deformations are computed in an Eulerian framework thanks to the backward characteristics. We use the Neo Hookean or Mooney Rivlin hyperelastic models and the elastic forces are incorporated as a source term in the incompressible Navier-Stokes equations. The velocity/pressure coupling is solved with a pressure-correction method and the equations are discretized by finite volume schemes on a Cartesian grid. The main difficulty resides in that large deformations in the fluid cause numerical instabilities. In order to avoid these problems, we use a re-initialization process for the level set and linear extrapolation of the backward characteristics. First, we verify and validate our approach on several test cases, including the benchmark of FSI proposed by Turek. Next, we apply this method to study the wave damping phenomenon which is a mean to reduce the waves impact on the coastline. So far, to our knowledge, only simulations with rigid or one dimensional elastic structure has been studied in the literature. We propose to place elastic structures on the seabed and we present results where 50 % of waves energy is absorbed.

Keywords: damping wave, Eulerian formulation, finite volume, fluid structure interaction, hyperelastic material

Procedia PDF Downloads 315
2150 Nutritive Value of Three-Stage Olive Cake (Olea europaea L.) for Growing Rabbit

Authors: Zahia Dorbane, Si Ammar Kadi, Dalila Boudouma, Thierry Gidenne

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In rabbits feeding, minimum fibre intake is essential to avoid digestive disorders. However, this concentration of fibre is not easy to obtain when formulating feeds, without reduction of nutritional value. Three stage olive cake, the residual material after oil extraction by centrifugation, including pulp and stones, can be used as a fibre source in rabbit diet. The incorporation of olive cake can allow a better balance between different fibre fractions and reduce health disorder. However, for practical use of any raw material, it is necessary to know its chemical and nutritive value. The aim of this study was to assess the nutritive value of three-stage olive cake (TSOC) for growing rabbits. Thus, 36 rabbits weaned at 35 days (702.8 ± 28.5) were divided into three groups of 12 receiving one of the following diets: control with 0% of TSOC, TSOC10 (10% of TSOC) and TSOC20 (20% TSOC). The rabbits were individually housed in digestibility cages and received ad libitum one of the three diets, fresh and clean water was provided ad libitum. After an adaptation period of 7d, feces were collected for 4d. Collected feces were frozen and stored for further analysis. The chemical composition of TSOC shows that it is a rich fiber raw material since it contains (%DM): 6% of CP; 7.4% of EE; 78.7% of NDF; 55.4% of ADF and 24.3% of ADL. The inclusion of TSOC at 20% of basal diet reduced the digestibility coefficient of organic matter, crude protein and NDF from 67.8 to 55.3%, 80.4 to 75.3% and from 31.5 to 18.4% (p < 0.001) respectively. The digestible energy and digestible protein content of the three-stage olive cake estimated by regression was 2.94 ± 0.52MJ DE/kg DM and 22.4 ± 6 g DP/kg DM respectively. In conclusion, based on the results of the present experiment, the three-stage olive cake can be used as a fibre source for rabbit.

Keywords: digestibility, nutritive value, olive cake, rabbit

Procedia PDF Downloads 149
2149 Concentration of Waste Waters by Enzyme-Assisted Low-Temperature Evaporation

Authors: Ahokas Mikko, Taskila Sanna, Varrio Kalle, Tanskanen Juha

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The present research aimed at the development of an energy efficient process for the concentration of starchy waste waters. The selected principle is mechanical vapor recompression evaporation (MVR) which leads to concentrated solid material and evaporated water phase. Evaporation removes water until a certain viscosity limit is reached. Materials with high viscosity cannot be concentrated using standard evaporators due to limitations of pumps and other constraints, such as wetting. Control of viscosity is thus essential for efficient evaporation. This applies especially to fluids in which due starch or other compounds the viscosity tends to increase via removal of water. In the present research, the effect of enzymes on evaporation of highly viscous starch industry waste waters was investigated. Wastewater samples were received from starch industry at pH of 4.8. Response surface methodology (RSM) was applied for the investigation of factor effects on the behaviour of concentrate during evaporation. The RSM was prepared using quadratic face-centered central composite design (CCF). The evaporation performance was evaluated by monitoring the viscosity of fluid during processing. Based on viscosity curves, the addition of glucoamylase reduced the viscosity during evaporation. This assumption was confirmed by CCF, suggesting that the use of starch decomposing glucoamylase allowed evaporation of the starchy wastewater to a relatively high total solid concentration without a detrimental increase in the viscosity. The results suggest that use of enzymes for reduction of viscosity during the evaporation allows more effective concentration of the wastewater and thereby recovery of potable water.

Keywords: viscous, wastewater, treatment, evaporation, concentration

Procedia PDF Downloads 240
2148 A Novel Cold Asphalt Concrete Mixture for Heavily Trafficked Binder Course

Authors: Anmar Dulaimi, Hassan Al Nageim, Felicite Ruddock, Linda Seton

Abstract:

Cold bituminous asphalt mixture (CBEM) provide a sustainable, cost effective and energy efficiency alternative to traditional hot mixtures. However, these mixtures have a comparatively low initial strength and as it is considered as evolutionary materials, mainly in the early life where the initial cohesion is low and builds up slowly. On the other hand, asphalt concrete is, by far, the most common mixtures in use as binder course and base in road pavement in the UK having a continuous grade offer a good aggregate interlock results in this material having very good load-spreading properties as well as a high resistance to permanent deformation. This study aims at developing a novel fast curing cold asphalt concrete binder course mixtures by using Ordinary Portland Cement (OPC) as a replacement to conventional mineral filler (0%-100%) while new by-product material (LJMU-A2) was used as a supplementary cementitious material. With this purpose, cold asphalt concrete binder course mixtures with cationic emulsions were studied by means of stiffness modulus whereas water sensitivity was approved by assessing the stiffness modulus ratio before and after sample conditioning. The results indicate that a substantial enhancement in the stiffness modulus and a considerable improvement of water sensitivity resistance by adding of LJMU-A2 to the cold asphalt mixtures as a supplementary cementitious material. Moreover, the addition of LJMU-A2 to those mixtures leads to stiffness modulus after 2- day curing comparable to those obtained with Portland cement after 7-day curing.

Keywords: cold mix asphalt, binder course, cement, stiffness modulus, water sensitivity

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2147 Three Dimensional Dynamic Analysis of Water Storage Tanks Considering FSI Using FEM

Authors: S. Mahdi S. Kolbadi, Ramezan Ali Alvand, Afrasiab Mirzaei

Abstract:

In this study, to investigate and analyze the seismic behavior of concrete in open rectangular water storage tanks in two-dimensional and three-dimensional spaces, the Finite Element Method has been used. Through this method, dynamic responses can be investigated together in fluid storages system. Soil behavior has been simulated using tanks boundary conditions in linear form. In this research, in addition to flexibility of wall, the effects of fluid-structure interaction on seismic response of tanks have been investigated to account for the effects of flexible foundation in linear boundary conditions form, and a dynamic response of rectangular tanks in two-dimensional and three-dimensional spaces using finite element method has been provided. The boundary conditions of both rigid and flexible walls in two-dimensional finite element method have been considered to investigate the effect of wall flexibility on seismic response of fluid and storage system. Furthermore, three-dimensional model of fluid-structure interaction issue together with wall flexibility has been analyzed under the three components of earthquake. The obtained results show that two-dimensional model is also accurately near to the results of three-dimension as well as flexibility of foundation leads to absorb received energy and relative reduction of responses.

Keywords: dynamic behavior, flexible wall, fluid-structure interaction, water storage tank

Procedia PDF Downloads 178
2146 Investigation of Mechanical Properties of Aluminum Tailor Welded Blanks

Authors: Dario Basile, Manuela De Maddis, Raffaella Sesana, Pasquale Russo Spena, Roberto Maiorano

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Nowadays, the reduction of CO₂ emissions and the decrease in energy consumption are the main aims of several industries, especially in the automotive sector. To comply with the increasingly restrictive regulations, the automotive industry is constantly looking for innovative techniques to produce lighter, more efficient, and less polluting vehicles. One of the latest technologies, and still developing, is based on the fabrication of the body-in-white and car parts through the stamping of Aluminum Tailor Welded Blanks. Tailor Welded Blanks (TWBs) are generally the combination of two/three metal sheets with different thicknesses and/or mechanical strengths, which are commonly butt-welded together by laser sources. The use of aluminum TWBs has several advantages such as low density and corrosion resistance adequate. However, their use is still limited by the lower formability with respect to the parent materials and the more intrinsic difficulty of laser welding of aluminum sheets (i.e., internal porosity) that, although its use in automated industries is constantly growing, remains a process to be further developed and improved. This study has investigated the effect of the main laser welding process parameters (laser power, welding speed, and focal distance) on the mechanical properties of aluminum TWBs made of 6xxx series. The research results show that a narrow weldability window can be found to ensure welded joints with high strength and limited or no porosity.

Keywords: aluminum sheets, automotive industry, laser welding, mechanical properties, tailor welded blanks

Procedia PDF Downloads 104
2145 Numerical Reproduction of Hemodynamic Change Induced by Acupuncture to ST-36

Authors: Takuya Suzuki, Atsushi Shirai, Takashi Seki

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Acupuncture therapy is one of the treatments in traditional Chinese medicine. Recently, some reports have shown the effectiveness of acupuncture. However, its full acceptance has been hindered by the lack of understanding on mechanism of the therapy. Acupuncture applied to Zusanli (ST-36) enhances blood flow volume in superior mesenteric artery (SMA), yielding peripheral vascular resistance – regulated blood flow of SMA dominated by the parasympathetic system and inhibition of sympathetic system. In this study, a lumped-parameter approximation model of blood flow in the systemic arteries was developed. This model was extremely simple, consisting of the aorta, carotid arteries, arteries of the four limbs and SMA, and their peripheral vascular resistances. Here, the individual artery was simplified to a tapered tube and the resistances were modelled by a linear resistance. We numerically investigated contribution of the peripheral vascular resistance of SMA to the systemic blood distribution using this model. In addition to the upstream end of the model, which correlates with the left ventricle, two types of boundary condition were applied; mean left ventricular pressure which correlates with blood pressure (BP) and mean cardiac output which corresponds to cardiac index (CI). We examined it to reproduce the experimentally obtained hemodynamic change, in terms of the ratio of the aforementioned hemodynamic parameters from their initial values before the acupuncture, by regulating the peripheral vascular resistances and the upstream boundary condition. First, only the peripheral vascular resistance of SMA was changed to show contribution of the resistance to the change in blood flow volume in SMA, expecting reproduction of the experimentally obtained change. It was found, however, this was not enough to reproduce the experimental result. Then, we also changed the resistances of the other arteries together with the value given at upstream boundary. Here, the resistances of the other arteries were changed simultaneously in the same amount. Consequently, we successfully reproduced the hemodynamic change to find that regulation of the upstream boundary condition to the value experimentally obtained after the stimulation is necessary for the reproduction, though statistically significant changes in BP and CI were not observed in the experiment. It is generally known that sympathetic and parasympathetic tones take part in regulation of whole the systemic circulation including the cardiac function. The present result indicates that stimulation to ST-36 could induce vasodilation of peripheral circulation of SMA and vasoconstriction of that of other arteries. In addition, it implies that experimentally obtained small changes in BP and CI induced by the acupuncture may be involved in the therapeutic response.

Keywords: acupuncture, hemodynamics, lumped-parameter approximation, modeling, systemic vascular resistance

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2144 Improving Carbon Dioxide Mass Transfer in Open Pond Raceway Systems for Improved Algal Productivity

Authors: William Middleton, Nodumo Zulu, Sue Harrison

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Open raceway ponds are currently the most used system for the commercial cultivation of algal biomass, as it is a cost-effective means of production. However, raceway ponds suffer from lower algal productivity when compared to closed photobioreactors. This is due to poor gas exchange between the fluid and the atmosphere. Carbon dioxide (CO₂) mass transfer is a large concern in the production of algae in raceway pond systems. The utilization of atmospheric CO₂ does not support maximal growth; however, CO₂ supplementation in the form of flue gas or concentrated CO₂ is not cost-effective. The introduction of slopes into the raceway system presents a possible improvement to the mass transfer from the air, as seen in previous work conducted at CeBER. Slopes improve turbulence (decreasing the concentration gradient of dissolved CO₂) and can cause air entrainment (allowing for greater surface area and contact time between the air and water). This project tests the findings of previous studies conducted in an indoor lab-scale raceway on a larger scale under outdoor conditions. The addition of slopes resulted in slightly increased CO₂ mass transfer as well as algal growth rate and productivity. However, there were reductions in energy consumption and average fluid velocity in the system. These results indicate a potential to improve the economic feasibility of algal biomass production, but further economic assessment would need to be carried out.

Keywords: algae, raceway ponds, mass transfer, algal culture, biotechnology, reactor design

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2143 Determination of Brominated Flame Retardants In Recycled Plastic Toys Using Thermal Desorption GC/MS

Authors: Athena Nguyen, Rojin Belganeh

Abstract:

In recycling plastics industries, waste plastics are converted into monomers and other useful molecules by chemical reactions. Thermal energy generated by incineration is recovered when waste plastics melt. During the process, Flame retardants containing products get in, and brominated flame retardants (BFRs) are often used to reduce the flammability of products. Some of the originally formulated brominated flame retardants additives are restricted by the RoHS Directive, such as PBDE and PBB. The determination of BFRs other than those restricted by the RoHS directive is required. Frontier Lab developed a pyrolyzer based on the vertical micro-furnace design. The multi-mode pyrolyzer with different modes of operations, including evolve gas analysis (EGA), flash pyrolysis, thermal desorption, heart cutting, allows users to choose among the techniques for their analysis purposes. The method requires very little sample preparation. The first step is to perform an EGA using temperature programs. This technique provides information about the thermal temperature behaviors of the sample. The EGA thermogram is then used to determine the next steps in the analysis process. In this presentation, with an Optimal thermal temperature zone identified based on EGA thermogram, thermal desorption GC/MS is a chosen technique for the determination of brominated flame retardants in recycled plastic toys. Five types of general-purpose brominated flame retardants other than those restricted by the RoHS Directive are determined by the standard addition method.

Keywords: gas chromatography/mass spectrometry, pyrolysis, pyrolyzer, thermal desorption-GC/MS

Procedia PDF Downloads 181
2142 Local Differential Privacy-Based Data-Sharing Scheme for Smart Utilities

Authors: Veniamin Boiarkin, Bruno Bogaz Zarpelão, Muttukrishnan Rajarajan

Abstract:

The manufacturing sector is a vital component of most economies, which leads to a large number of cyberattacks on organisations, whereas disruption in operation may lead to significant economic consequences. Adversaries aim to disrupt the production processes of manufacturing companies, gain financial advantages, and steal intellectual property by getting unauthorised access to sensitive data. Access to sensitive data helps organisations to enhance the production and management processes. However, the majority of the existing data-sharing mechanisms are either susceptible to different cyber attacks or heavy in terms of computation overhead. In this paper, a privacy-preserving data-sharing scheme for smart utilities is proposed. First, a customer’s privacy adjustment mechanism is proposed to make sure that end-users have control over their privacy, which is required by the latest government regulations, such as the General Data Protection Regulation. Secondly, a local differential privacy-based mechanism is proposed to ensure the privacy of the end-users by hiding real data based on the end-user preferences. The proposed scheme may be applied to different industrial control systems, whereas in this study, it is validated for energy utility use cases consisting of smart, intelligent devices. The results show that the proposed scheme may guarantee the required level of privacy with an expected relative error in utility.

Keywords: data-sharing, local differential privacy, manufacturing, privacy-preserving mechanism, smart utility

Procedia PDF Downloads 67
2141 Identification and Characterisation of Oil Sludge Degrading Bacteria Isolated from Compost

Authors: O. Ubani, H. I. Atagana, M. S. Thantsha, R. Adeleke

Abstract:

The oil sludge components (polycyclic aromatic hydrocarbons, PAHs) have been found to be cytotoxic, mutagenic and potentially carcinogenic and microorganisms such as bacteria and fungi can degrade the oil sludge to less toxic compounds such as carbon dioxide, water and salts. In the present study, we isolated different bacteria with PAH-degrading potentials from the co-composting of oil sludge and different animal manure. These bacteria were isolated on the mineral base medium and mineral salt agar plates as a growth control. A total of 31 morphologically distinct isolates were carefully selected from 5 different compost treatments for identification using polymerase chain reaction (PCR) of the 16S rDNA gene with specific primers (16S-P1 PCR and 16S-P2 PCR). The amplicons were sequenced and sequences were compared with the known nucleotides from the gene bank database. The phylogenetical analyses of the isolates showed that they belong to 3 different clades namely Firmicutes, Proteobacteria and Actinobacteria. These bacteria identified were closely related to genera Bacillus, Arthrobacter, Staphylococcus, Brevibacterium, Variovorax, Paenibacillus, Ralstonia and Geobacillus species. The results showed that Bacillus species were more dominant in all treated compost piles. Based on their characteristics these bacterial isolates have high potential to utilise PAHs of different molecular weights as carbon and energy sources. These identified bacteria are of special significance in their capacity to emulsify the PAHs and their ability to utilize them. Thus, they could be potentially useful for bioremediation of oil sludge and composting processes.

Keywords: bioaugmentation, biodegradation, bioremediation, composting, oil sludge, PAHs, animal manures

Procedia PDF Downloads 246
2140 Bed Evolution under One-Episode Flushing in a Truck Sewer in Paris, France

Authors: Gashin Shahsavari, Gilles Arnaud-Fassetta, Alberto Campisano, Roberto Bertilotti, Fabien Riou

Abstract:

Sewer deposits have been identified as a major cause of dysfunctions in combined sewer systems regarding sewer management, which induces different negative consequents resulting in poor hydraulic conveyance, environmental damages as well as worker’s health. In order to overcome the problematics of sedimentation, flushing has been considered as the most operative and cost-effective way to minimize the sediments impacts and prevent such challenges. Flushing, by prompting turbulent wave effects, can modify the bed form depending on the hydraulic properties and geometrical characteristics of the conduit. So far, the dynamics of the bed-load during high-flow events in combined sewer systems as a complex environment is not well understood, mostly due to lack of measuring devices capable to work in the “hostile” in combined sewer system correctly. In this regards, a one-episode flushing issue from an opening gate valve with weir function was carried out in a trunk sewer in Paris to understanding its cleansing efficiency on the sediments (thickness: 0-30 cm). During more than 1h of flushing within 5 m distance in downstream of this flushing device, a maximum flowrate and a maximum level of water have been recorded at 5 m in downstream of the gate as 4.1 m3/s and 2.1 m respectively. This paper is aimed to evaluate the efficiency of this type of gate for around 1.1 km (from the point -50 m to +1050 m in downstream from the gate) by (i) determining bed grain-size distribution and sediments evolution through the sewer channel, as well as their organic matter content, and (ii) identifying sections that exhibit more changes in their texture after the flush. For the first one, two series of sampling were taken from the sewer length and then analyzed in laboratory, one before flushing and second after, at same points among the sewer channel. Hence, a non-intrusive sampling instrument has undertaken to extract the sediments smaller than the fine gravels. The comparison between sediments texture after the flush operation and the initial state, revealed the most modified zones by the flush effect, regarding the sewer invert slope and hydraulic parameters in the zone up to 400 m from the gate. At this distance, despite the increase of sediment grain-size rages, D50 (median grain-size) varies between 0.6 mm and 1.1 mm compared to 0.8 mm and 10 mm before and after flushing, respectively. Overall, regarding the sewer channel invert slope, results indicate that grains smaller than sands (< 2 mm) are more transported to downstream along about 400 m from the gate: in average 69% before against 38% after the flush with more dispersion of grain-sizes distributions. Furthermore, high effect of the channel bed irregularities on the bed material evolution has been observed after the flush.

Keywords: bed-load evolution, combined sewer systems, flushing efficiency, sediments transport

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2139 Synthesis of Plant-Mediated Silver Nanoparticles Using Erythrina indica Extract and Evaluation of Their Anti-Microbial Activities

Authors: Chandra Sekhar Singh, P. Chakrapani, B. Arun Jyothi, A. Roja Rani

Abstract:

The green synthesis of metallic nanoparticles (NPs) involves biocompatible ingredients under physiological conditions of temperature and pressure. Moreover, the biologically active molecules involved in the green synthesis of NPs act as functionalizing ligands, making these NPs more suitable for biomedical applications. Among the most important bioreductants are plant extracts, which are relatively easy to handle, readily available, low cost, and have been well explored for the green synthesis of other nanomaterials. Various types of metallic NPs have already been synthesized using plant extracts. They have wide applicability in various areas such as electronics, catalysis, chemistry, energy, and medicine. Metallic nanoparticles are traditionally synthesized by wet chemical techniques, where the chemicals used are quite often toxic and flammable. In our study, we were described a cost effective and environment friendly technique for green synthesis of silver nanoparticles from 1mM AgNO3 solution through the aqueous extract of Erythrina indica as reducing as well as capping agent. Nanoparticles were characterized using UV–Vis absorption spectroscopy, FTIR, XRD, X-ray diffraction, SEM and TEM analysis showed the average particle size of 30 nm as well as revealed their spherical structure. Further these biologically synthesized nanoparticles were found to be highly toxic against different human pathogens viz. two Gram positive namely Klebsiella pneumonia and Bacillus subtilis bacteria and two were Gram negative bacteria namely Staphylococcus aureus and Escherichia coli (E. coli). This is for the first time reporting that Erythrina indica plant extract was used for the synthesis of nanoparticles.

Keywords: silver nanoparticles, green synthesis, antibacterial activity, FTIR, TEM, SEM

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2138 Feasibility of Iron Scrap Recycling with Considering Demand-Supply Balance

Authors: Reina Kawase, Yuzuru Matsuoka

Abstract:

To mitigate climate change, to reduce CO2 emission from steel sector, energy intensive sector, is essential. One of the effective countermeasure is recycling of iron scrap and shifting to electric arc furnace. This research analyzes the feasibility of iron scrap recycling with considering demand-supply balance and quantifies the effective by CO2 emission reduction. Generally, the quality of steel made from iron scrap is lower than the quality of steel made from basic oxygen furnace. So, the constraint of demand side is goods-wise steel demand and that of supply side is generation of iron scap. Material Stock and Flow Model (MSFM_demand) was developed to estimate goods-wise steel demand and generation of iron scrap and was applied to 35 regions which aggregated countries in the world for 2005-2050. The crude steel production was estimated under two case; BaU case (No countermeasures) and CM case (With countermeasures). For all the estimation periods, crude steel production is greater than generation of iron scrap. This makes it impossible to substitute electric arc furnaces for all the basic oxygen furnaces. Even though 100% recycling rate of iron scrap, under BaU case, CO2 emission in 2050 increases by 12% compared to that in 2005. With same condition, 32% of CO2 emission reduction is achieved in CM case. With a constraint from demand side, the reduction potential is 6% (CM case).

Keywords: iron scrap recycling, CO2 emission reduction, steel demand, MSFM demand

Procedia PDF Downloads 546
2137 Population Centralization in Urban Area and Metropolitans in Developing Countries: A Case Study of Urban Centralization in Iran

Authors: Safar Ghaedrahmati, Leila Soltani

Abstract:

Population centralization in urban area and metropolitans, especially in developing countries such as Iran increase metropolitan's problems. For few decades, the population of cities in developing countries, including Iran had a higher growth rate than the total growth rate of countries’ population. While in developed countries, the development of the big cities began decades ago and generally allowed for controlled and planned urban expansion, the opposite is the case in developing countries, where rapid urbanization process is characterized by an unplanned existing urban expansion. The developing metropolitan cities have enormous difficulties in coping both with the natural population growth and the urban physical expansion. Iranian cities are usually the heart of economic and cultural changes that have occurred after the Islamic revolution in 1979. These cities are increasingly having impacts via political–economical arrangement and chiefly by urban management structures. Structural features have led to the population growth of cities and urbanization (in number, population and physical frame) and the main problems in them. On the other hand, the lack of birth control policies and the deceptive attractions of cities, particularly big cities, and the birth rate has shot up, something which has occurred mainly in rural regions and small cities. The population of Iran has increased rapidly since 1956. The 1956 and 1966 decennial censuses counted the population of Iran at 18.9 million and 25.7 million, respectively, with a 3.1% annual growth rate during the 1956–1966 period. The 1976 and 1986 decennial censuses counted Iran’s population at 33.7 and 49.4 million, respectively, a 2.7% and 3.9% annual growth rate during the 1966–1976 and 1976–1986 periods. The 1996 count put Iran’s population at 60 million, a 1.96% annual growth rate from 1986–1996 and the 2006 count put Iran population at 72 million. A recent major policy of urban economic and industrial decentralization is a persistent program of the government. The policy has been identified as a result of the massive growth of Tehran in the recent years, up to 9 million by 2010. Part of the growth of the capitally resulted from the lack of economic opportunities elsewhere and in order to redress the developing primacy of Tehran and the domestic pressures which it is undergoing, the policy of decentralization is to be implemented as quickly as possible. Type of research is applied and method of data collection is documentary and methods of analysis are; population analysis with urban system analysis and urban distribution system

Keywords: population centralization, cities of Iran, urban centralization, urban system

Procedia PDF Downloads 292
2136 On the Influence of Thermal Radiation Upon Heat Transfer Characteristics of a Porous Media Under Local Thermal Non-Equilibrium Condition

Authors: Yasser Mahmoudi, Nader Karimi

Abstract:

The present work investigates numerically the effect of thermal radiation from the solid phase on the rate of heat transfer inside a porous medium. Forced convection heat transfer process within a pipe filled with a porous media is considered. The Darcy-Brinkman-Forchheimer model is utilized to represent the fluid transport within the porous medium. A local thermal non-equilibrium (LTNE), two-equation model is used to represent the energy transport for the solid and fluid phases. The radiative heat transfer equation is solved by discrete ordinate method (DOM) to compute the radiative heat flux in the porous medium. Two primary approaches (models A and B) are used to represent the boundary conditions for constant wall heat flux. The effects of radiative heat transfer on the Nusselt numbers of the two phases are examined by comparing the results obtained by the application of models A and B. The fluid Nusselt numbers calculated by the application of models A and B show that the Nusselt number obtained by model A for the radiative case is higher than those predicted for the non-radiative case. However, for model B the fluid Nusselt numbers obtained for the radiative and non-radiative cases are similar.

Keywords: porous media, local thermal non-equilibrium, forced convection heat transfer, thermal radiation, Discrete Ordinate Method (DOM)

Procedia PDF Downloads 319
2135 Estimating Affected Croplands and Potential Crop Yield Loss of an Individual Farmer Due to Floods

Authors: Shima Nabinejad, Holger Schüttrumpf

Abstract:

Farmers who are living in flood-prone areas such as coasts are exposed to storm surges increased due to climate change. Crop cultivation is the most important economic activity of farmers, and in the time of flooding, agricultural lands are subject to inundation. Additionally, overflow saline water causes more severe damage outcomes than riverine flooding. Agricultural crops are more vulnerable to salinity than other land uses for which the economic damages may continue for a number of years even after flooding and affect farmers’ decision-making for the following year. Therefore, it is essential to assess what extent the agricultural areas are flooded and how much the associated flood damage to each individual farmer is. To address these questions, we integrated farmers’ decision-making at farm-scale with flood risk management. The integrated model includes identification of hazard scenarios, failure analysis of structural measures, derivation of hydraulic parameters for the inundated areas and analysis of the economic damages experienced by each farmer. The present study has two aims; firstly, it attempts to investigate the flooded cropland and potential crop damages for the whole area. Secondly, it compares them among farmers’ field for three flood scenarios, which differ in breach locations of the flood protection structure. To achieve its goal, the spatial distribution of fields and cultivated crops of farmers were fed into the flood risk model, and a 100-year storm surge hydrograph was selected as the flood event. The study area was Pellworm Island that is located in the German Wadden Sea National Park and surrounded by North Sea. Due to high salt content in seawater of North Sea, crops cultivated in the agricultural areas of Pellworm Island are 100% destroyed by storm surges which were taken into account in developing of depth-damage curve for analysis of consequences. As a result, inundated croplands and economic damages to crops were estimated in the whole Island which was further compared for six selected farmers under three flood scenarios. The results demonstrate the significance and the flexibility of the proposed model in flood risk assessment of flood-prone areas by integrating flood risk management and decision-making.

Keywords: crop damages, flood risk analysis, individual farmer, inundated cropland, Pellworm Island, storm surges

Procedia PDF Downloads 254
2134 Inbreeding Study Using Runs of Homozygosity in Nelore Beef Cattle

Authors: Priscila A. Bernardes, Marcos E. Buzanskas, Luciana C. A. Regitano, Ricardo V. Ventura, Danisio P. Munari

Abstract:

The best linear unbiased predictor (BLUP) is a method commonly used in genetic evaluations of breeding programs. However, this approach can lead to higher inbreeding coefficients in the population due to the intensive use of few bulls with higher genetic potential, usually presenting some degree of relatedness. High levels of inbreeding are associated to low genetic viability, fertility, and performance for some economically important traits and therefore, should be constantly monitored. Unreliable pedigree data can also lead to misleading results. Genomic information (i.e., single nucleotide polymorphism – SNP) is a useful tool to estimate the inbreeding coefficient. Runs of homozygosity have been used to evaluate homozygous segments inherited due to direct or collateral inbreeding and allows inferring population selection history. This study aimed to evaluate runs of homozygosity (ROH) and inbreeding in a population of Nelore beef cattle. A total of 814 animals were genotyped with the Illumina BovineHD BeadChip and the quality control was carried out excluding SNPs located in non-autosomal regions, with unknown position, with a p-value in the Hardy-Weinberg equilibrium lower than 10⁻⁵, call rate lower than 0.98 and samples with the call rate lower than 0.90. After the quality control, 809 animals and 509,107 SNPs remained for analyses. For the ROH analysis, PLINK software was used considering segments with at least 50 SNPs with a minimum length of 1Mb in each animal. The inbreeding coefficient was calculated using the ratio between the sum of all ROH sizes and the size of the whole genome (2,548,724kb). A total of 25.711 ROH were observed, presenting mean, median, minimum, and maximum length of 3.34Mb, 2Mb, 1Mb, and 80.8Mb, respectively. The number of SNPs present in ROH segments varied from 50 to 14.954. The longest ROH length was observed in one animal, which presented a length of 634Mb (24.88% of the genome). Four bulls were among the 10 animals with the longest extension of ROH, presenting 11% of ROH with length higher than 10Mb. Segments longer than 10Mb indicate recent inbreeding. Therefore, the results indicate an intensive use of few sires in the studied data. The distribution of ROH along the chromosomes showed that chromosomes 5 and 6 presented a large number of segments when compared to other chromosomes. The mean, median, minimum, and maximum inbreeding coefficients were 5.84%, 5.40%, 0.00%, and 24.88%, respectively. Although the mean inbreeding was considered low, the ROH indicates a recent and intensive use of few sires, which should be avoided for the genetic progress of breed.

Keywords: autozygosity, Bos taurus indicus, genomic information, single nucleotide polymorphism

Procedia PDF Downloads 144
2133 Time-Interval between Rectal Cancer Surgery and Reintervention for Anastomotic Leakage and the Effects of a Defunctioning Stoma: A Dutch Population-Based Study

Authors: Anne-Loes K. Warps, Rob A. E. M. Tollenaar, Pieter J. Tanis, Jan Willem T. Dekker

Abstract:

Anastomotic leakage after colorectal cancer surgery remains a severe complication. Early diagnosis and treatment are essential to prevent further adverse outcomes. In the literature, it has been suggested that earlier reintervention is associated with better survival, but anastomotic leakage can occur with a highly variable time interval to index surgery. This study aims to evaluate the time-interval between rectal cancer resection with primary anastomosis creation and reoperation, in relation to short-term outcomes, stratified for the use of a defunctioning stoma. Methods: Data of all primary rectal cancer patients that underwent elective resection with primary anastomosis during 2013-2019 were extracted from the Dutch ColoRectal Audit. Analyses were stratified for defunctioning stoma. Anastomotic leakage was defined as a defect of the intestinal wall or abscess at the site of the colorectal anastomosis for which a reintervention was required within 30 days. Primary outcomes were new stoma construction, mortality, ICU admission, prolonged hospital stay and readmission. The association between time to reoperation and outcome was evaluated in three ways: Per 2 days, before versus on or after postoperative day 5 and during primary versus readmission. Results: In total 10,772 rectal cancer patients underwent resection with primary anastomosis. A defunctioning stoma was made in 46.6% of patients. These patients had a lower anastomotic leakage rate (8.2% vs. 11.6%, p < 0.001) and less often underwent a reoperation (45.3% vs. 88.7%, p < 0.001). Early reoperations (< 5 days) had the highest complication and mortality rate. Thereafter the distribution of adverse outcomes was more spread over the 30-day postoperative period for patients with a defunctioning stoma. Median time-interval from primary resection to reoperation for defunctioning stoma patients was 7 days (IQR 4-14) versus 5 days (IQR 3-13 days) for no-defunctioning stoma patients. The mortality rate after primary resection and reoperation were comparable (resp. for defunctioning vs. no-defunctioning stoma 1.0% vs. 0.7%, P=0.106 and 5.0% vs. 2.3%, P=0.107). Conclusion: This study demonstrated that early reinterventions after anastomotic leakage are associated with worse outcomes (i.e. mortality). Maybe the combination of a physiological dip in the cellular immune response and release of cytokines following surgery, as well as a release of endotoxins caused by the bacteremia originating from the leakage, leads to a more profound sepsis. Another explanation might be that early leaks are not contained to the pelvis, leading to a more profound sepsis requiring early reoperations. Leakage with or without defunctioning stoma resulted in a different type of reinterventions and time-interval between surgery and reoperation.

Keywords: rectal cancer surgery, defunctioning stoma, anastomotic leakage, time-interval to reoperation

Procedia PDF Downloads 128