A Vertical Axis Wind Turbine (VAWT) comprises multiple parts constructed from different materials. This complexity presents challenges in designing the blade structure. In this study, we investigated a structural optimization of a small-scale blade for a VAWT, with Finite Element Analysis (FEA) model. The purpose is to minimize the blade mass while adhering to a suite of critical wind conditions according to the IEC 61400-2 Standard. The structure made from Aluminum material simulates structure’s global behavior to determine maximum stress and deflection levels. The same structure is modeled using Glass/Epoxy composite for optimizing its design. Twenty combinations of Glass/Epoxy layers, varying in ply thickness and orientation, are simulated to find the most suitable combination. Results demonstrated that the optimization case [45°/90°/0°/−45°] obtained the minimum values of stress and deflection, is 59% lighter than Aluminum blade (initial design). The designed Glass/Epoxy composite blade is acceptable and recommended for structural safety.

A Vertical Axis Wind Turbine (VAWT) comprises multiple parts constructed from different materials. This complexity presents challenges in designing the blade structure. In this study, we investigated a structural optimization of a small-scale blade for a VAWT, with Finite Element Analysis (FEA) model. The purpose is to minimize the blade mass while adhering to a suite of critical wind conditions according to the IEC 61400-2 Standard. The structure made from Aluminum material simulates structure’s global behavior to determine maximum stress and deflection levels. The same structure is modeled using Glass/Epoxy composite for optimizing its design. Twenty combinations of Glass/Epoxy layers, varying in ply thickness and orientation, are simulated to find the most suitable combination. Results demonstrated that the optimization case [45°/90°/0°/−45°] obtained the minimum values of stress and deflection, is 59% lighter than Aluminum blade (initial design). The designed Glass/Epoxy composite blade is acceptable and recommended for structural safety.

Reservoir dams in Algeria face reduced lifespans and diminished water resources due to sedimentation, which often leads to out-of-service states. To address this issue, topo-bathymetry has been identified as the preferred technique for predicting silting in dam basins. Consequently, the seek for optimal interpolation methods to conduct topo-bathymetric surveys has become increasingly important. This study compares two primary interpolation methods, deterministic and geostatistical, to determine the most effective approach for these surveys. Three specific techniques were examined in this research: inverse distance weighting, radial basis function (deterministic), and ordinary kriging (geostatistical). The study focused on five reservoir dams in Algeria, using cross-validation to assess the performance of each interpolation method. The results revealed that the geostatistical approach outperformed deterministic estimations across all five sites. The superiority of the geostatistical method was further supported by the performance metrics used in the study. Based on these findings, ordinary kriging emerged as the most suitable method for interpolating topo-bathymetric surveys for all sites, regardless of variations in morphology and spatial sampling density. This research contributes valuable insights for enhancing reservoir dam management in Algeria in order to optimize water resource allocation.

Reservoir dams in Algeria face reduced lifespans and diminished water resources due to sedimentation, which often leads to out-of-service states. To address this issue, topo-bathymetry has been identified as the preferred technique for predicting silting in dam basins. Consequently, the seek for optimal interpolation methods to conduct topo-bathymetric surveys has become increasingly important. This study compares two primary interpolation methods, deterministic and geostatistical, to determine the most effective approach for these surveys. Three specific techniques were examined in this research: inverse distance weighting, radial basis function (deterministic), and ordinary kriging (geostatistical). The study focused on five reservoir dams in Algeria, using cross-validation to assess the performance of each interpolation method. The results revealed that the geostatistical approach outperformed deterministic estimations across all five sites. The superiority of the geostatistical method was further supported by the performance metrics used in the study. Based on these findings, ordinary kriging emerged as the most suitable method for interpolating topo-bathymetric surveys for all sites, regardless of variations in morphology and spatial sampling density. This research contributes valuable insights for enhancing reservoir dam management in Algeria in order to optimize water resource allocation.

Reservoir dams in Algeria face reduced lifespans and diminished water resources due to sedimentation, which often leads to out-of-service states. To address this issue, topo-bathymetry has been identified as the preferred technique for predicting silting in dam basins. Consequently, the seek for optimal interpolation methods to conduct topo-bathymetric surveys has become increasingly important. This study compares two primary interpolation methods, deterministic and geostatistical, to determine the most effective approach for these surveys. Three specific techniques were examined in this research: inverse distance weighting, radial basis function (deterministic), and ordinary kriging (geostatistical). The study focused on five reservoir dams in Algeria, using cross-validation to assess the performance of each interpolation method. The results revealed that the geostatistical approach outperformed deterministic estimations across all five sites. The superiority of the geostatistical method was further supported by the performance metrics used in the study. Based on these findings, ordinary kriging emerged as the most suitable method for interpolating topo-bathymetric surveys for all sites, regardless of variations in morphology and spatial sampling density. This research contributes valuable insights for enhancing reservoir dam management in Algeria in order to optimize water resource allocation.

Water resources are facing significant challenges in result of rapidly growing demand, deteriorating quality, and the effects of climate change. Today, water quantity and quality issues have become prevalent in various regions across the globe, affecting both northern and southern territories. Among the sectors reliant on this resource, irrigation stands out as the largest consumer of water. When surface water becomes inaccessible due to insufficient precipitation or other factors, the use of groundwater becomes the only viable alternative for irrigation. The Remila Plain (Khenchela) is located in an endorean watershed in northeastern Algeria and extends over 250 km2 in a synclinal basin filled with water from the Mio-Plio Quaternary - the main aquifer of the region, widely used for irrigation. The aim of this work is to study the hydrochemistry of these waters, as well as the evolution of mineralisation, the identification of the origin of the chemistry, and the suitability of these waters for irrigation. Initial results indicate an evolution of mineralisation in the direction of groundwater flow, with electrical conductivity values varying between 1000μS/cm in the recharge zones, and 2700μS/cm at the outlet. This mineralisation is mainly due to the dissolution of evaporitic minerals and the alteration of silicates. In addition, the various water quality indices used indicate that the water can be used for irrigation without major risk to plants and soils.

Water resources are facing significant challenges in result of rapidly growing demand, deteriorating quality, and the effects of climate change. Today, water quantity and quality issues have become prevalent in various regions across the globe, affecting both northern and southern territories. Among the sectors reliant on this resource, irrigation stands out as the largest consumer of water. When surface water becomes inaccessible due to insufficient precipitation or other factors, the use of groundwater becomes the only viable alternative for irrigation. The Remila Plain (Khenchela) is located in an endorean watershed in northeastern Algeria and extends over 250 km2 in a synclinal basin filled with water from the Mio-Plio Quaternary - the main aquifer of the region, widely used for irrigation. The aim of this work is to study the hydrochemistry of these waters, as well as the evolution of mineralisation, the identification of the origin of the chemistry, and the suitability of these waters for irrigation. Initial results indicate an evolution of mineralisation in the direction of groundwater flow, with electrical conductivity values varying between 1000μS/cm in the recharge zones, and 2700μS/cm at the outlet. This mineralisation is mainly due to the dissolution of evaporitic minerals and the alteration of silicates. In addition, the various water quality indices used indicate that the water can be used for irrigation without major risk to plants and soils.

Water resources are facing significant challenges in result of rapidly growing demand, deteriorating quality, and the effects of climate change. Today, water quantity and quality issues have become prevalent in various regions across the globe, affecting both northern and southern territories. Among the sectors reliant on this resource, irrigation stands out as the largest consumer of water. When surface water becomes inaccessible due to insufficient precipitation or other factors, the use of groundwater becomes the only viable alternative for irrigation. The Remila Plain (Khenchela) is located in an endorean watershed in northeastern Algeria and extends over 250 km2 in a synclinal basin filled with water from the Mio-Plio Quaternary - the main aquifer of the region, widely used for irrigation. The aim of this work is to study the hydrochemistry of these waters, as well as the evolution of mineralisation, the identification of the origin of the chemistry, and the suitability of these waters for irrigation. Initial results indicate an evolution of mineralisation in the direction of groundwater flow, with electrical conductivity values varying between 1000μS/cm in the recharge zones, and 2700μS/cm at the outlet. This mineralisation is mainly due to the dissolution of evaporitic minerals and the alteration of silicates. In addition, the various water quality indices used indicate that the water can be used for irrigation without major risk to plants and soils.

Water resources are facing significant challenges in result of rapidly growing demand, deteriorating quality, and the effects of climate change. Today, water quantity and quality issues have become prevalent in various regions across the globe, affecting both northern and southern territories. Among the sectors reliant on this resource, irrigation stands out as the largest consumer of water. When surface water becomes inaccessible due to insufficient precipitation or other factors, the use of groundwater becomes the only viable alternative for irrigation. The Remila Plain (Khenchela) is located in an endorean watershed in northeastern Algeria and extends over 250 km2 in a synclinal basin filled with water from the Mio-Plio Quaternary - the main aquifer of the region, widely used for irrigation. The aim of this work is to study the hydrochemistry of these waters, as well as the evolution of mineralisation, the identification of the origin of the chemistry, and the suitability of these waters for irrigation. Initial results indicate an evolution of mineralisation in the direction of groundwater flow, with electrical conductivity values varying between 1000μS/cm in the recharge zones, and 2700μS/cm at the outlet. This mineralisation is mainly due to the dissolution of evaporitic minerals and the alteration of silicates. In addition, the various water quality indices used indicate that the water can be used for irrigation without major risk to plants and soils.

Water resources are facing significant challenges in result of rapidly growing demand, deteriorating quality, and the effects of climate change. Today, water quantity and quality issues have become prevalent in various regions across the globe, affecting both northern and southern territories. Among the sectors reliant on this resource, irrigation stands out as the largest consumer of water. When surface water becomes inaccessible due to insufficient precipitation or other factors, the use of groundwater becomes the only viable alternative for irrigation. The Remila Plain (Khenchela) is located in an endorean watershed in northeastern Algeria and extends over 250 km2 in a synclinal basin filled with water from the Mio-Plio Quaternary - the main aquifer of the region, widely used for irrigation. The aim of this work is to study the hydrochemistry of these waters, as well as the evolution of mineralisation, the identification of the origin of the chemistry, and the suitability of these waters for irrigation. Initial results indicate an evolution of mineralisation in the direction of groundwater flow, with electrical conductivity values varying between 1000μS/cm in the recharge zones, and 2700μS/cm at the outlet. This mineralisation is mainly due to the dissolution of evaporitic minerals and the alteration of silicates. In addition, the various water quality indices used indicate that the water can be used for irrigation without major risk to plants and soils.

Inspired by a real-work case, this paper introduces a profit maximization model for dynamic lot sizing considering substitution and multiple usage of returns for refurbishing at different levels of quality or for disassembly to extract key parts that will be used in the manufacturing process. This model allows studying the interactions between different types of returns and decisions. To analyze the impact of uncertainty on these interactions, we develop a robust two-stage stochastic program with uncertainty on demands and returns. The resulting problems are mixed-integer linear programs that we solve using an efficient relax-and-fix and fix-and-optimize heuristic. Extensive numerical experiments are conducted to study the different trade-offs when integrating multi-usage of returns with substitution and accordingly derive managerial insights. The experiments have revealed, for example, that: (i) the profit margin of the refurbished items is the main determinant of the total profit and when such margin in high, the total profit becomes more sensitive to different cost variations; (ii) collection efficiency becomes very sensitive to collection cost and much less sensitive to refurbishing cost especially with large profit margins; (iii) when demand and returns are uncertain parameters, substitution becomes the best option as uncertainty and prices increase; (iv) when the gap between prices of different quality levels is high, lost sales occur mainly on the lowest quality product and downgrading decreases together with substitution; and (v) Sharing the production line between refurbishing and manufacturing for low-quality products is highly motivated by small upgrading costs and their substitution level increases with increasing upgrading costs.

Inspired by a real-work case, this paper introduces a profit maximization model for dynamic lot sizing considering substitution and multiple usage of returns for refurbishing at different levels of quality or for disassembly to extract key parts that will be used in the manufacturing process. This model allows studying the interactions between different types of returns and decisions. To analyze the impact of uncertainty on these interactions, we develop a robust two-stage stochastic program with uncertainty on demands and returns. The resulting problems are mixed-integer linear programs that we solve using an efficient relax-and-fix and fix-and-optimize heuristic. Extensive numerical experiments are conducted to study the different trade-offs when integrating multi-usage of returns with substitution and accordingly derive managerial insights. The experiments have revealed, for example, that: (i) the profit margin of the refurbished items is the main determinant of the total profit and when such margin in high, the total profit becomes more sensitive to different cost variations; (ii) collection efficiency becomes very sensitive to collection cost and much less sensitive to refurbishing cost especially with large profit margins; (iii) when demand and returns are uncertain parameters, substitution becomes the best option as uncertainty and prices increase; (iv) when the gap between prices of different quality levels is high, lost sales occur mainly on the lowest quality product and downgrading decreases together with substitution; and (v) Sharing the production line between refurbishing and manufacturing for low-quality products is highly motivated by small upgrading costs and their substitution level increases with increasing upgrading costs.

Inspired by a real-work case, this paper introduces a profit maximization model for dynamic lot sizing considering substitution and multiple usage of returns for refurbishing at different levels of quality or for disassembly to extract key parts that will be used in the manufacturing process. This model allows studying the interactions between different types of returns and decisions. To analyze the impact of uncertainty on these interactions, we develop a robust two-stage stochastic program with uncertainty on demands and returns. The resulting problems are mixed-integer linear programs that we solve using an efficient relax-and-fix and fix-and-optimize heuristic. Extensive numerical experiments are conducted to study the different trade-offs when integrating multi-usage of returns with substitution and accordingly derive managerial insights. The experiments have revealed, for example, that: (i) the profit margin of the refurbished items is the main determinant of the total profit and when such margin in high, the total profit becomes more sensitive to different cost variations; (ii) collection efficiency becomes very sensitive to collection cost and much less sensitive to refurbishing cost especially with large profit margins; (iii) when demand and returns are uncertain parameters, substitution becomes the best option as uncertainty and prices increase; (iv) when the gap between prices of different quality levels is high, lost sales occur mainly on the lowest quality product and downgrading decreases together with substitution; and (v) Sharing the production line between refurbishing and manufacturing for low-quality products is highly motivated by small upgrading costs and their substitution level increases with increasing upgrading costs.

Inspired by a real-work case, this paper introduces a profit maximization model for dynamic lot sizing considering substitution and multiple usage of returns for refurbishing at different levels of quality or for disassembly to extract key parts that will be used in the manufacturing process. This model allows studying the interactions between different types of returns and decisions. To analyze the impact of uncertainty on these interactions, we develop a robust two-stage stochastic program with uncertainty on demands and returns. The resulting problems are mixed-integer linear programs that we solve using an efficient relax-and-fix and fix-and-optimize heuristic. Extensive numerical experiments are conducted to study the different trade-offs when integrating multi-usage of returns with substitution and accordingly derive managerial insights. The experiments have revealed, for example, that: (i) the profit margin of the refurbished items is the main determinant of the total profit and when such margin in high, the total profit becomes more sensitive to different cost variations; (ii) collection efficiency becomes very sensitive to collection cost and much less sensitive to refurbishing cost especially with large profit margins; (iii) when demand and returns are uncertain parameters, substitution becomes the best option as uncertainty and prices increase; (iv) when the gap between prices of different quality levels is high, lost sales occur mainly on the lowest quality product and downgrading decreases together with substitution; and (v) Sharing the production line between refurbishing and manufacturing for low-quality products is highly motivated by small upgrading costs and their substitution level increases with increasing upgrading costs.

Introduction/purpose : This study investigates the seismic response of longspan continuous deck truss bridges under the effect of near-fault vertical ground motions. The primary objective is to assess how near-fault vertical seismic excitation affects the structural safety and performance of these bridges. By exploring the nuanced dynamics induced by near-fault vertical motions, the research aims to improve the understanding of the vulnerabilities and challenges faced by long-span continuous deck truss bridges during seismic events.

Methods : To achieve this objective, the truss bridge was subjected to a series of ground motions, representing natural seismic events. The seismic response of the bridge was investigated by applying the linear time history method to the 3D finite element model. This analysis focused specifically on the evaluation of base shear and displacement. The analysis was extended to include the seismic performance of truss structures. The comparison between the bridge responses with and without consideration of the vertical component of ground motion was made to clarify the effect of vertical excitation.

Results : The results show that there is a significant contribution of vertical excitation, particularly concerning the internal force in the truss elements, where it exceeded 60 % during a severe earthquake, and consequently increased the demand-to-capacity ratio in most elements of the truss bridge structure.

Conclusion : For structural engineers and designers, the results of this research suggest that neglecting to include the vertical ground motion component in the analytical assessments of this type of bridges can lead to a greater degree of uncertainty and risk, particularly in near-fault regions.

Introduction/purpose : This study investigates the seismic response of longspan continuous deck truss bridges under the effect of near-fault vertical ground motions. The primary objective is to assess how near-fault vertical seismic excitation affects the structural safety and performance of these bridges. By exploring the nuanced dynamics induced by near-fault vertical motions, the research aims to improve the understanding of the vulnerabilities and challenges faced by long-span continuous deck truss bridges during seismic events.

Methods : To achieve this objective, the truss bridge was subjected to a series of ground motions, representing natural seismic events. The seismic response of the bridge was investigated by applying the linear time history method to the 3D finite element model. This analysis focused specifically on the evaluation of base shear and displacement. The analysis was extended to include the seismic performance of truss structures. The comparison between the bridge responses with and without consideration of the vertical component of ground motion was made to clarify the effect of vertical excitation.

Results : The results show that there is a significant contribution of vertical excitation, particularly concerning the internal force in the truss elements, where it exceeded 60 % during a severe earthquake, and consequently increased the demand-to-capacity ratio in most elements of the truss bridge structure.

Conclusion : For structural engineers and designers, the results of this research suggest that neglecting to include the vertical ground motion component in the analytical assessments of this type of bridges can lead to a greater degree of uncertainty and risk, particularly in near-fault regions.

Introduction/purpose : This study investigates the seismic response of longspan continuous deck truss bridges under the effect of near-fault vertical ground motions. The primary objective is to assess how near-fault vertical seismic excitation affects the structural safety and performance of these bridges. By exploring the nuanced dynamics induced by near-fault vertical motions, the research aims to improve the understanding of the vulnerabilities and challenges faced by long-span continuous deck truss bridges during seismic events.

Methods : To achieve this objective, the truss bridge was subjected to a series of ground motions, representing natural seismic events. The seismic response of the bridge was investigated by applying the linear time history method to the 3D finite element model. This analysis focused specifically on the evaluation of base shear and displacement. The analysis was extended to include the seismic performance of truss structures. The comparison between the bridge responses with and without consideration of the vertical component of ground motion was made to clarify the effect of vertical excitation.

Results : The results show that there is a significant contribution of vertical excitation, particularly concerning the internal force in the truss elements, where it exceeded 60 % during a severe earthquake, and consequently increased the demand-to-capacity ratio in most elements of the truss bridge structure.

Conclusion : For structural engineers and designers, the results of this research suggest that neglecting to include the vertical ground motion component in the analytical assessments of this type of bridges can lead to a greater degree of uncertainty and risk, particularly in near-fault regions.

Introduction/purpose : This study investigates the seismic response of longspan continuous deck truss bridges under the effect of near-fault vertical ground motions. The primary objective is to assess how near-fault vertical seismic excitation affects the structural safety and performance of these bridges. By exploring the nuanced dynamics induced by near-fault vertical motions, the research aims to improve the understanding of the vulnerabilities and challenges faced by long-span continuous deck truss bridges during seismic events.

Methods : To achieve this objective, the truss bridge was subjected to a series of ground motions, representing natural seismic events. The seismic response of the bridge was investigated by applying the linear time history method to the 3D finite element model. This analysis focused specifically on the evaluation of base shear and displacement. The analysis was extended to include the seismic performance of truss structures. The comparison between the bridge responses with and without consideration of the vertical component of ground motion was made to clarify the effect of vertical excitation.

Results : The results show that there is a significant contribution of vertical excitation, particularly concerning the internal force in the truss elements, where it exceeded 60 % during a severe earthquake, and consequently increased the demand-to-capacity ratio in most elements of the truss bridge structure.

Conclusion : For structural engineers and designers, the results of this research suggest that neglecting to include the vertical ground motion component in the analytical assessments of this type of bridges can lead to a greater degree of uncertainty and risk, particularly in near-fault regions.

Introduction/purpose : This study investigates the seismic response of longspan continuous deck truss bridges under the effect of near-fault vertical ground motions. The primary objective is to assess how near-fault vertical seismic excitation affects the structural safety and performance of these bridges. By exploring the nuanced dynamics induced by near-fault vertical motions, the research aims to improve the understanding of the vulnerabilities and challenges faced by long-span continuous deck truss bridges during seismic events.

Methods : To achieve this objective, the truss bridge was subjected to a series of ground motions, representing natural seismic events. The seismic response of the bridge was investigated by applying the linear time history method to the 3D finite element model. This analysis focused specifically on the evaluation of base shear and displacement. The analysis was extended to include the seismic performance of truss structures. The comparison between the bridge responses with and without consideration of the vertical component of ground motion was made to clarify the effect of vertical excitation.

Results : The results show that there is a significant contribution of vertical excitation, particularly concerning the internal force in the truss elements, where it exceeded 60 % during a severe earthquake, and consequently increased the demand-to-capacity ratio in most elements of the truss bridge structure.

Conclusion : For structural engineers and designers, the results of this research suggest that neglecting to include the vertical ground motion component in the analytical assessments of this type of bridges can lead to a greater degree of uncertainty and risk, particularly in near-fault regions.

Introduction/purpose : This study investigates the seismic response of longspan continuous deck truss bridges under the effect of near-fault vertical ground motions. The primary objective is to assess how near-fault vertical seismic excitation affects the structural safety and performance of these bridges. By exploring the nuanced dynamics induced by near-fault vertical motions, the research aims to improve the understanding of the vulnerabilities and challenges faced by long-span continuous deck truss bridges during seismic events.

Methods : To achieve this objective, the truss bridge was subjected to a series of ground motions, representing natural seismic events. The seismic response of the bridge was investigated by applying the linear time history method to the 3D finite element model. This analysis focused specifically on the evaluation of base shear and displacement. The analysis was extended to include the seismic performance of truss structures. The comparison between the bridge responses with and without consideration of the vertical component of ground motion was made to clarify the effect of vertical excitation.

Results : The results show that there is a significant contribution of vertical excitation, particularly concerning the internal force in the truss elements, where it exceeded 60 % during a severe earthquake, and consequently increased the demand-to-capacity ratio in most elements of the truss bridge structure.

Conclusion : For structural engineers and designers, the results of this research suggest that neglecting to include the vertical ground motion component in the analytical assessments of this type of bridges can lead to a greater degree of uncertainty and risk, particularly in near-fault regions.