International Review of Applied Sciences and Engineering
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International Review of Applied Sciences and Engineering is a peer reviewed journal. It offers a comprehensive range of articles on all aspects of engineering and applied sciences. It provides an international and interdisciplinary platform for the exchange of ideas between engineers, researchers and scholars within the academy and industry. It covers a wide range of application areas including architecture, building services and energetics, civil engineering, electrical engineering and mechatronics, environmental engineering, mechanical engineering, material sciences, applied informatics and management sciences. The aim of the Journal is to provide a location for reporting original research results having international focus with multidisciplinary content. The published papers provide solely new basic information for designers, scholars and developers working in the mentioned fields. The papers reflect the broad categories of interest in: optimisation, simulation, modelling, control techniques, monitoring, and development of new analysis methods, equipment and system conception.
Founder: Debreceni Egyetem
Publisher: Akadémiai Kiadó
URL: https://akjournals.com/view/journals/1848/1848-overview.xml
ISSN 2062-0810 (Print)
ISSN 2063-4269 (Online)
Founder: Debreceni Egyetem
Publisher: Akadémiai Kiadó
URL: https://akjournals.com/view/journals/1848/1848-overview.xml
ISSN 2062-0810 (Print)
ISSN 2063-4269 (Online)
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International Review of Applied Sciences and Engineering Cím szerinti böngészés
Megjelenítve 1 - 20 (Összesen 191)
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Tétel Szabadon hozzáférhető A comparative analysis of sport and economic success through the example of top- and mid-ranking Hungarian water polo clubs(Akadémiai Kiadó, 2022-10-27) Mészáros, Anett; Bács, Bence András; Bácsné Bába, Éva; Madarász, Tamás; igenThe biggest question of professional sports is how to compete successfully in the global economic framework, simultaneously in terms of the sport and in economic terms. As a result, in addition to indicators measuring sports-related effectiveness, the need for an economic analysis of sport has also emerged. Most academic research into the economic aspects of sports are related to the analysis of North American major league sports, as well as to European football. Water polo is also a spectator team sport, yet its economic analysis is almost entirely missing. In this article, we present an economic analysis of the operation of five men’s water polo teams – the top four teams in terms of the sports results and one from the mid-range – competing in the highest-level national championship in Hungary. Our aim is to determine, on the basis of the analysis of the data, the relationship between effectiveness in sports and the economic background of the teams. It can undoubtedly be concluded that, in addition to appropriate professional decisions, it is the economic situation of a club that has a clear impact on their effectiveness; in other words, up to a certain point, the more disposable funds and wider range of assets a sports company has, the more effectively it can prepare and the better results it will have in the various domestic and international championships and tournaments. CIT (corporate income tax benefits, “TAO” in Hungarian) support is fundamentally important in the field of youth sports development. While professional sports in Hungary are built on the development of junior players, there is still no clear link between the successfulness of the adult and the junior teams. The first-division teams of the clubs providing the best junior players are frequently in the mid-range or occasionally among the weakest teams in the national championship. Our research has shown that apart from the fact that some teams are extremely successful in the water polo championship, the outcome of many matches becomes quite predictable. Based on these, the uncertainty of the outcome is compromised, and the championship becomes less exciting and also loses some of its audience.Tétel Szabadon hozzáférhető A comparative study of the competitive balance of the Spanish and English top football leagues on the basis of sport performance during the four last seasons before the Covid-19 pandemic(Akadémiai Kiadó, 2023-05-09) Nagy, Kristóf; Bács, Bence András; Bácsné Bába, Éva; igenThe topic of this study has been the examination and comparison of the competitive balance of the Spanish and the English first leagues of soccer, called La Liga Santander and Barclays Premier League. The basis for the research project has been provided by a database of sixteen hundred elements, containing the data of the two leagues starting from the 2014/2015 season up to the 2017/2018 season. When choosing the time period for the study, we intended to avoid having to deal with the impact of Covid-19, which is why we picked exactly these competition seasons. We have primarily used statistical indicators. In the case of sports-related data, our inquiries have included the following: comparing and averaging the winning percentages per season, furthermore, the winning percentages of championship seasons, the distribution of goals scored and conceded and, finally, the calculation of the Herfindahl-Hirschman Index. Although there is one aspect of investigation according to which the competition balance of La Liga is closer to the optimal, the dispersion of winning percentages and the indicator of the goals conceded as well as the HHI index show that the Premier League is the more balanced competition of the two.Tétel Szabadon hozzáférhető A hybrid DMO-RERNN based UPFC controller for transient stability analysis in grid connected wind-diesel-PV hybrid system(Akadémiai Kiadó, 2023-10-10) Thanigaivel, K.; Ramesh, S.; Karunanithi, K.; nemIn this paper, a novel hybrid technique is proposed for transient stability analysis on grid connected Wind-Diesel-PV hybrid system. The proposed hybrid methodology is combination of the dwarf mongoose optimization algorithm (DMO) and the recalling enhanced recurrent neural network (RERNN) named DMO-RERNN. The main purpose of this work is to consider various elements on hybrid system for the analysis of transient stability according to different conditions. The voltage profile of hybrid system is enhanced using the proposed unified power flow controller (UPFC), which also has higher performance improving transient performance compared to the conventional ANN, PI and fuzzy-sliding mode controller. Considering the proposed technique, DMO is used to find the optimal global solution for the fault predicted by the RERNN approach. The proposed system is executed on MATLAB work platform; its performance with existing systems is analyzed. The result proves that the proposed hybrid technique based UPFC controller provides better results compared with other existing technique. The efficiency of the PI is 82.136, ANN is 77, Fuzzy Sliding Mode is 65.097% and proposed technique is 97.99038%.Tétel Szabadon hozzáférhető A novel approach of multi-loop control based-ADRC for improving lower knee position exoskeleton system(Akadémiai Kiadó, 2023-05-09) Alawad, Nasir Ahmed; Humaidi, Amjad Jaleel; Alaraji, Ahmed Sabah; nemThis study revealed the system of a lower limb exoskeleton created for knee rehabilitation. The exoskeleton has been extensively used in rehabilitation robotic device research, but its practical applicability is limited due to its high nonlinearity and uncertain behavior. As a result, the control technique is critical in increasing the efficacy of rehabilitation devices. For the rehabilitation and help of a patient with a lower-limb condition, a sliding mode control (SMC) with proportional derivative (PD) control approach are used as parallel loops. Active disturbances rejection control (ADRC) is used by these controllers to cancel any external influences. To overcome the degradation of disturbance rejection and robustness caused by a failure to fully adjust for the entire disturbance, a (SMC) loop was introduced to the control regulation. By assessing performance indices related to the estimated inaccuracy, the results demonstrate the effectiveness of the suggested controller. Simulink is used for simulation and analysis.Tétel Szabadon hozzáférhető A statistics-based review on island detection methods in microgrids: Overall investigation and state-of-the-art(Akadémiai Kiadó, 2023-05-09) Amin, Damanjani; Mohamad , Hosseini Abardeh; Azita , Azarfar; Mehrdad, Hojjat; nemIn this paper, a comprehensive statistics-based review of islanding detection methods (IDMs) in microgrids (MGs) is presented. Islanding detection is the situation of isolating the MG from the main grid whether programmed as a result of load managing purposes or un-programmed due to the occurrence of faults. Islanding detection is a vital issue in MG's analyses due to the prevention of subsequent protection problems in the power system. In other words, when the MG's operation mode changes, the current passing through the protective devices changes subsequently and the protection system should be able to adapt the new settings to the protective devices. So, IDMs are vital for electrical engineers to overcome the abovementioned protection issue. This review paper surveys the existing literature in IDMs by concentration on total publications, type of publications (journal, conference paper, or book), five authors with the highest number of publications (including the affiliations), and five most published sources. Also, the five most cited publications and state-of-the-art IDMs are investigated in detail, utilizing some known and novel categorizations. This paper will be useful for the MG's researchers to know the most desirable IDMs, especially in recent years, and provides an insightful overview for future studies.Tétel Szabadon hozzáférhető Accelerated curing effects on performance of metakaolin concrete(Akadémiai Kiadó, 2023-10-10) Dubey, Moulshree; Deo, Shirish V.; Ramtekkar, Gangadhar; nemThe manufacturing of cement liberates the green-house gasses into atmosphere. To overcome this problem so many alternative materials has been invented by researchers to minimize addition of cement. The incorporation of these alternative materials as cementitious material in concrete enhances the attributes of concrete. In this scenario metakaolin gained momentum as a substitution to cement in concrete. Most of the researchers studied the performance of concrete incorporating metakaolin as cementitious material in normal curing conditions. There is a need for analysing the impact of accelerated curing on properties of concrete by incorporating metakaolin as cementitious material. The current construction industry needs high early strength for removal of form work in early ages. The accelerated curing is a method which provides high early strength. In this study, different proportions of metakaolin are added as partial alternative to cement and cured in accelerated curing tank for 3.5 h. The strength parameters test, durability test, and micro-structural parameter tests are performed on these samples. Further, micro-structural analysis has been carried out using SEM, and EDX tests. Results depicted the incorporation of 15% of metakaolin as substitute to cement amplifies the overall performance of concrete in accelerated curing regime.Tétel Szabadon hozzáférhető Adaptive backstepping control design for ball and beam system(Akadémiai Kiadó, 2021-12) Al-Dujaili, Ayad Q.; Humaidi, Amjad J.; Pereira, Daniel Augusto; Ibraheem, Ibraheem Kasim; nemBall and Beam system is one of the most popular and important laboratory models for teaching control systems. This paper proposes a new control strategy to the position control for the ball and beam system. Firstly, a nonlinear controller is proposed based on the backstepping approach. Secondly, in order to adapt online the dynamic control law, adaptive laws are developed to estimate the uncertain parameters. The stability of the proposed adaptive backstepping controller is proved based on the Lyapunov theorem. Simulated results are presented to illustrate the performance of the proposed approach.Tétel Szabadon hozzáférhető An application of filtered back projection method for computed tomography images(Akadémiai Kiadó, 2021-08) Onur, Tuğba Özge; nemMathematical methods take an important part in reconstruction technologies of radiographic image. Back projection, iterative, and analytical (Two-dimensional Fourier, Filtered Back Projection) methods are the most important procedures for image reconstruction. Whenever there exists numerous projections, analytical methods have a great performance in speed and accuracy and due to these advantages they are comprehensively used for X-ray imaging. One of the widespread used methods in tomographic image reconstruction is Filtered Back Projection (FBP) algorithm. This paper presents an application of this reconstruction algorithm for a generated image of the object. Shepp-Logan filter is used to form the filtered back projection image and performance improvement is investigated. The obtained images indicate that FBP algorithm can be substantial for various applications in the field of medicine and industry.Tétel Szabadon hozzáférhető An assessment of advanced DC-link based reversing voltage type multilevel inverter topologies(Akadémiai Kiadó, 2023-02-13) Nagaraja, Rao S.; Manjunatha, B.M.; Suresh , Kumar A.; Kiran, Kumar B.M.; Satish, Kumar R.; Pranupa, S.; nemIn this paper, advanced DC-Link (DCL) based reversing voltage type Multilevel Inverter (MLI) to- pologies by compensating the difficulties in the conventional MLIs are reviewed. These topologies consist of less switching components and driver circuits when compared with conventional MLIs predominantly in higher levels. Consequently, installation area, total cost and hardware difficulties are reduced by increasing the voltage levels. The unipolar based Pulse Width Modulation Schemes (PWMS) will improve DCL inverters performance. This paper presents unipolar Multi-Reference (MR) based sine and space vector PWMS with single triangular carrier wave for generating required levels in output voltage. Comparison between UMR sine and space vector PWMS for DCL inverter topologies is pre- sented in terms of Fundamental Output Voltage (FOV) and Total Harmonic Distortion (THD). The research tries to establish the survey analysis for single-phase 7-level DCL based reversing voltage type MLI topologies with UMR based sine and space vector PWMs. Finally, to confirm the feasibility of proposed DCL-MLIs in terms of FOV and THD the simulation results are incorporated. Further, the prototype model is developed for single-phase 7-level DCL inverter with Field Programmable Gate Array (FPGA) based UMR sine and space vector PWMS to authenticate simulation results. The effi- ciency of the proposed cascaded MLI achieves the value of 99.003%.Tétel Szabadon hozzáférhető An innovative approach for harmonising availability and energy efficiency in data centres: A case study(Akadémiai Kiadó, 2019-06-01) Kunbaz, Mahmoud; Bieser, Jürgen; nemA Data Centre (DC) as critical, energy-hungry infrastructure is dominated by two main driving forces: i) Availability and ii) Energy requirements. As a result of increasing energy costs, algorithms for optimising energy efficiency have been devised. However, these algorithms do not take availability into consideration. This paper aims to present a combination of Failure Mode, Effects and Criticality Analysis (FMECA)/Reliability, Availability, Maintainability (RAM)/Energy Analysis as an innovative approach for harmonising availability and energy efficiency in DC. Based on various measures defined by FMECA/RAM, corresponding availability and reliability are modelled and calculated. In parallel, potential energy saving measures are included in RAM simulation to quantify their influence on the availability and reliability of DC infrastructure. As a result, a set of the most promising optimisation measures is selected. Results show that some energy saving measures are highly correlated with availability. However, required data centre availability can be achieved with improved energy efficiency if the right set of optimisation measures is implemented. This approach guides DC managers to identify improvement potentials in terms of availability and energy efficiency, providing a reliable decision basis for future investments.Tétel Szabadon hozzáférhető An investigation on the performance and emission studies on diesel engine by addition of nanoparticles and antioxidants as additives in biodiesel blends(Akadémiai Kiadó, 2021-08) Kumar, Siddavatam Naresh; Wani, Mohmad Marouf; nemThe study aims to examine the effects of palm biodiesel blended with additives in the compression ignition (CI) engine. Biodiesel as fuel was limited by challenges such as lower calorific value (CV) and higher viscosity while increasing brake specific fuel consumption (BSFC) and nitrogen oxides (NOx) emissions. Nanoparticles and antioxidant additives added to biodiesel play an essential role in avoiding the hindrances of biodiesel. The antioxidants combined with biodiesel reduced NOx emissions by eliminating decomposing peroxides, free radicals, and preventing free radicals' chain reaction. The Significant characteristics of nanoparticles are high CV, high thermal conductivity, and higher surface to volume ratio. These characteristics are used to improve the CI engine's performance and emissions by using nanoparticles blended with biodiesel. Five different test blends of Diesel, B20, B20TO, B20AO, and B20AOTO were prepared. The result showed high brake thermal efficiency (BTHE) and decreased BSFC, exhaust gas temperature (EGT), hydrocarbons (HC), NOx, and HC emissions by using the B20AOTO fuel blend contrasted with other biodiesel blends.Tétel Szabadon hozzáférhető An IoT aware nature inspired Multilayer Hybrid Dropout Deep-learning paradigm for waste image classification and management(Akadémiai Kiadó, 2023-02-13) Ramesh Kumar , M.; Ashok Kumar , K.; Surender , R.; Melingi, S. B.; Tamizhselvan, C.; nemIn this manuscript, the combination of IoT and Multilayer Hybrid Dropout Deep-learning Model for waste image categorization is proposed to categorize the wastes as bio waste and non-bio waste. The input captured images are pre-processed and remove noises in the captured images. Under this approach, a Nature inspired Multilayer Hybrid Dropout Deep-learning Model is proposed. Multilayer Hybrid Dropout Deep-learning Model is the consolidation of deep convolutional neural network and Dropout Extreme Learning Machine classifier. Here, deep convolutional neural network is used for feature extraction and Dropout Extreme Learning Machine classifier for categorizing the waste images. To improve the classification accurateness, Horse herd optimization algorithm is used to optimize the parameter of the Dropout Extreme Learning Machine classifier. The objective function is to maximize the accuracy by minimize the computational complexity. The simulation is executed in MATLAB. The proposed Multilayer Hybrid Dropout Deep-learning Model and Horse herd optimization algorithm attains higher accuracy 39.56% and 42.46%, higher Precision 48.74% and 34.56%, higher F-Score 32.5% and 45.34%, higher Sensitivity 24.45% and 34.23%, higher Specificity 31.43% and 21.45%, lower execution time 0.019(s) and 0.014(s) compared with existing waste management and classification using convolutional neural network with hyper parameter of random search optimization algorithm waste management and classification using clustering approach with Ant colony optimization algorithm. Finally, the proposed method categorizes the waste image accurately.Tétel Szabadon hozzáférhető An ontology for sharing and managing information in disaster response: An illustrative case study of flood evacuation(Akadémiai Kiadó, 2020-04-01) Khantong, Sommai; Shari, Mohammad Nazir Ahmad; Mahmood, Ahmad Kamil; nemInformation management and sharing is an essential ingredient, but a difficult and challenging problem for disaster response management. This paper proposes an ontology as a model to organize and structure information in order to improve the information management and sharing in disaster response management. The ontology was designed and developed based on philosophically grounded foundational ontologies. It was also implemented in ontological languages and demonstrated and evaluated in a case study of the flood evacuation process. This paper also provides a systematic approach to develop a well-founded domain ontology that addresses both static and dynamic aspects of a given domain.Tétel Szabadon hozzáférhető Analysis of construction cost prediction studies – global perspective(Akadémiai Kiadó, 2019-12-01) Velumani, P.; Nampoothiri, N. V. N.; nemIt is well known that the civil engineering constructions are subjected to cost risk and time overruns. The uncertainties of the cost of construction many times result in disputes among stakeholders. The recent cost fluctuation in sand price in Tamil Nadu is a good example of time and cost overruns. There are too many models developed to predict the cost of construction by using different parameters and tools. The objectives of this research are to analyse the importance of research in this field, the countries focusing on this issue, level of implementation by the practicing engineers, the tools often or successfully used, the difficulties in predicting the cost and the accuracy of prediction and bringing out a useful conclusion to provide the direction for future research. In this research, a sample of 324 research papers out of more than 2000 papers listed in Scopus database between the years 1990 and 2015 were considered and analyzed on five factors. The five factors are 1) authors affiliation – academics, industry or both; 2) country; 3) tools used – ANN, regression, time-series models, etc.; 4) complexity involved or ease of use; 5) accuracy of results. The results show interesting information.Tétel Szabadon hozzáférhető Analysis of inelastic buckling of rectangular plates with a free edge using polynomial deflection functions(Akadémiai Kiadó, 2020-04-01) Eziefula, Uchechi G.; nemThe inelastic buckling behaviour of different rectangular thin isotropic plates having a free edge is studied. Various combinations of boundary conditions are subject to in-plane uniaxial compression and each rectangular plate is bounded by an unloaded free edge. The characteristic deflection function of each plate is formulated using a polynomial function in form of Taylor–Maclaurin series. A deformation plasticity approach is adopted and the buckling load equation is modified using a work principle technique. Buckling coefficients of the plates are calculated for various aspect ratios and moduli ratios. Findings obtained from the investigation are found to reasonably agree with data published in the literature.Tétel Szabadon hozzáférhető Application of nanofilters for ventilation(Akadémiai Kiadó, 2019-06-01) Rubina, Aleš; Rubinová, Olga; Blasinski, Petr; nemNanotechnology is a perspective manufacturing technology, and in the technical fields, it deals with the production, development and utilization of technologies and materials with dimensions in nanometre sizes (1–100 nm). Nanofilters used in the article for filtration purposes consist from a nanolayer which is applied to a coarse textile backing layer, and they are inserted into the frames as conventional textile filters. The most commonly used materials are PP and PE polymers, as well as carbon, glass and metal filters. With the fabrication of nanotechnology-based filter, it is very important to choose materials, polymers with specific properties, which can be used for filtration function of the product itself. The results given in the main article compare the nanofilters with the main representatives of existing filter products currently available on the market. There is a problem with high pressure loss of the nanomaterial, and when we compare them with traditional filters, it is difficult to use them in technical practice, even if there exists the possibility for us to define the material and the thickness of the layer which are adapted to the application-specific application conditions.Tétel Szabadon hozzáférhető Application of viscoelastic dampers for reducing dynamic response of high-speed railway bridges(Akadémiai Kiadó, 2020-08-01) Tahiri, Mohamed; Khamlichi, Abdellatif; Bezzazi, Mohammed; nemDue to the extensive development of high-speed railway lines which are operating at increasing velocities, the dynamic performance of railway bridges has become an important issue of scientific research. The aim of this study is to investigate the possibility of reducing the vertical acceleration and displacement of pre-stressed reinforced concrete bridges beams by using passive nonlinear viscoelastic dampers to retrofit them. The proposed solution is based on connecting the dampers directly to the abutments and the bottom surface of the bridge deck with an eccentricity between the neutral axis of the bridge and the contact point of the viscoelastic dampers. First, the dampers are modeled through the concept of linearized fractional derivatives to obtain energetic equivalent linear viscoelastic dampers. Optimization of the configuration of these dampers was performed then as function of the orientation angle and the eccentricity. Considering two bridges having different length that were studied in the literature with other systems of damping, it was found that the best orientation angle of dampers is close to 60°. It was found also that, in order to satisfy Eurocode 1 requirements, the total equivalent damping coefficient for the actual damping system is less than half of that required for systems using auxiliary beam to fix dampers, which indicates higher efficiency of the proposed solution.Tétel Szabadon hozzáférhető Applied real-valued genetic algorithm for an extended model of economic lot, purchase and delivery scheduling problem(Akadémiai Kiadó, 2022-06-16) Hasheminejad, Seyed Ali; Valipour, Khadijeh; Khoshnood, Hamid; nemSupply chain management intends to integrate supply chains' activities such as material flow, information flow and financial issues. Material flow management is the most significant issue since the inventory level in the whole supply chain could be optimized by an integrated plan. In other words, when one member of the supply chain plans to reduce its inventory level solely, despite reducing inventory in this node the inventory will be stocked in other partners' warehouses. Therefore, in this paper a new mathematical model has been developed to facilitate the process of finding the optimum solution in economic production, purchase and delivery lots and their schedules in a three-echelon supply chain environment; including raw material in suppliers, manufacturer and assembly facility as a customer. The manufacturer with a flow shop system provides its requirements from supplier, assemble multiple products, and delivers products to the customer (automotive OEM alike) on an optimum multiple delivery points. The delivery cycles would be identified through the production common cycle regarding the supply chain flexibility. Finally, a modified real-valued Genetic Algorithm (MRGA), and an Optimal Enumeration Method (OEM) are developed, and some numerical experiments have been done and compared as well.Tétel Szabadon hozzáférhető Assessment of mechanical and durability performance of silica fume and metakaolin as cementitious materials in high-performance concrete(Akadémiai Kiadó, 2024-01-22) Sankar, B.; Ramadoss, P.; nemThe present study aims to determine the effects of blending cementitious materials on the mechanical and durability properties of high-performance concrete (HPC). Densified silica fume and fine-grounded metakaolin are used as supplementary cementitious materials (SCMs). A total of 16 mixes containing both binary and ternary blending of SCMs were chosen for w/b ratios of 0.4 and 0.3 respectively. The hardened properties tested for the HPC mixes were compressive strength at 7, 28, and 90 days, flexural strength at 28 days, and modulus of elasticity at 28 days. Maximum strength gains up to 15%, 38%, and 23% for compression, flexure, and elastic modulus were observed in ternary mixes compared to binary mixes. Stress-strain behaviour of ternary mixes indicates increased tolerance of stress for the least amount of strain in the specimens. Based on the experimental results, empirical relations were developed and checked with the existing codes and by earlier researchers. The durability properties tested for HPC were water absorption at 28 days, acid attack, and sulphate attack at 28, 56, and 90 days. Ternary mixes improved the pore structure of HPC, resulting in a 56% reduction in water absorption and a 34% reduction in compressive strength loss due to immersion in 5% H2SO4 at 90 days. The findings of the study endorse that ternary blending of SF and MK can improve the engineering properties of HPC, and a mix containing SF 10% and MK 10% is recommended for the best results.Tétel Szabadon hozzáférhető Assessment of RANS turbulence closure models for predicting airflow in neutral ABL over hilly terrain(Akadémiai Kiadó, 2021-12) Narjisse, Amahjour; Abdellatif, Khamlichi; nemImplementing wind farms in heights of a hilly terrain where wind speed is expected to be large may be viewed as a means to increase wind energy production without occupying fertile lands. Micro sitting of a wind farm in these conditions can gain dramatically from CFD simulation of fluid flow in the ABL above complex topography. However, this issue still poses tough challenges regarding the turbulence model to be used and the way to operate the near wall treatment in the presence eventually of separation. In this work, prediction capacity of RANS turbulence models was studied for a typical hill under the assumption of steady state and incompressible airflow regime in neutral ABL. Two models were analyzed by using COMSOL Multiphysics software packages. These included standard k − ϵ , and shear-stress transport k − ω . The most up-to-date procedures dedicated to near wall treatment were applied along with refined closer coefficients adjusted for the particular case of ABL. Considering wind tunnel test data, performance of the previous models was discussed in terms of converging mesh, computational time, reattachment point position and propensity of the model to retrieve the right level of turbulence flow in conditions of neutral stratifications. Then, a numerical simulation of the turbulent airflow over two slopes shapes of the symmetry hill by the validation of the experimental data has been then carried out. Both turbulence models agree well with air-velocity tested windward of the hills H3 and H5. Therefore, it was found that the standard k − ϵ model performs very well at the different positions of the low slope hill, and at the summit of a steep hill, but it over-predicts wind speed close to the wall, which requires an improvement of the near-wall treatment. However, the S S T k − ω model in neutral case of the ABL was given consistent simulation results with experimental data for prediction of the flow separation and recirculation region at the leeward side of a steep hill, whereas standard k − ϵ model under the neutral condition and the S S T k − ω model by using standard coefficients were failed to predict accurately detailed characteristics of recirculation region process.