Search results

This paper aims to study passive control techniques for transonic flow over a backward-facing step (BFS) using square-lobed trailing edges. The study investigates the efficacy of upward and downward lobe patterns, different lobe widths and deflection angles on flow separation, aiming for a deeper understanding of the flow physics behind the passive flow control system.

Large Eddy Simulation and Reynolds-averaged Navier–Stokes were used to evaluate the results of the study. The research explores the impact of upward and downward patterns of lobes on flow separation through the effects of different lobe widths and deflection angles. Numerical methods are used to analyse the behaviour of transonic flow over BFS and compared it to existing experimental results.

The square-lobed trailing edges significantly enhance the reduction of mean reattachment length by up to 80%. At Ma = 0.8, the up-downward configuration demonstrates increased effectiveness in reducing the root mean square of pressure fluctuations at a proximity of 5-step height in the wake region, with a reduction of 50%, while the flat-downward configuration proves to be more efficient in reducing the root mean square of pressure fluctuations at a proximity of 1-step height in the near wake region, achieving a reduction of 71%. Furthermore, the study shows that the up-downward configuration triggers early spanwise velocity fluctuations, whereas the standalone flat-downward configuration displays less intense crosswise velocity fluctuations within the wake region.

The findings demonstrate the effectiveness of square-lobed trailing edges as passive control techniques, showing significant implications for improving efficiency, performance and safety of the design in aerospace and industrial systems.

This paper demonstrates that the square-lobed trailing edges are effective in reducing the mean reattachment length and pressure fluctuations in transonic conditions. The study evaluates the efficacy of different configurations, deflection angles and lobe widths on flow and provides insights into the flow physics of passive flow control systems.

This study aims to investigate the determinants of the food security status of participants and non-participants of livestock extension services living under similar socioeconomic conditions as livestock farming households in the Feed the Future zone of Bangladesh.

Cross-sectional data of 906 farm-households extracted from a total of 2064 from the Feed the Future representative Bangladesh Integrated Households Survey 2018 were used. A triple hurdle model combined with a structural equation model were used to analyze the data. The causal relationship between food security status, livestock extension services, technology adoption and women's empowerment was investigated by estimating structural equation modeling with second-order latent factors.

The results indicate that livestock extension services have increased livestock technology adoption and have a positively significant (p < 0.01) relationship with household wealth, food security, welfare and women's empowerment.

The results suggest that livestock extension services have an impact on new technology adoption and enhancing women's empowerment; thus, the services should be widely made available in the region.

The peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-11-2021-0647.

The paper aims to expand the scope of application of the lattice Boltzmann method (LBM), especially in the field of aircraft engineering. The traditional LBM is usually applied to incompressible flows at a low Reynolds number, which is not sufficient to satisfy the needs of aircraft engineering. Devoted to tackling the defect, the paper proposes a developed LBM combining the subgrid model and the multiple relaxation time (MRT) approach. A multilayer adaptive Cartesian grid method to improve the computing efficiency of the traditional LBM is also employed.

The subgrid model and the multilayer adaptive Cartesian grid are introduced into MRT-LBM for simulations of incompressible flows at a high Reynolds number. Validated by several typical flow simulations, the numerical methods in this paper can efficiently study the flows under high Reynolds numbers.

Some numerical simulations for the lid-driven flow of cavity, flow around iced GLC305, LB606b and ONERA-M6 are completed. The paper presents the investigation results, indicating that the methods are accurate and effective for the separated flow after icing.

LBM is developed with the addition of the subgrid model and the MRT method. A numerical strategy is proposed using a multilayer adaptive Cartesian grid method and its treatment of boundary conditions. The paper refers to innovative algorithm developments and applications to the aircraft engineering, especially for iced wing simulations with flow separations.

Policymakers are developing government-level pandemic response strategies (GPRS) to assist architecture, engineering and construction (AEC) enterprises. However, the effectiveness of the GPRS has not been assessed. Therefore, this study aims to investigate the interrelationships between GPRS and AEC enterprises. To achieve that aim, the study objectives are to compare GPRS effectiveness between small-medium and large AEC enterprises, develop groupings to categorize interrelated GPRS and evaluate the effectiveness of the GPRS and interrelated constructs.

A systematic literature review and semi-structured interviews with 40 AEC industry professionals were carried out, generating 22 GPRS. Then, questionnaire survey data was collected among AEC professionals. In total, 114 valid survey answers were received and analyzed using the Kruskal–Wallis H test, normalized mean analysis, factor analysis and fuzzy synthetic evaluation.

Small-medium enterprises have four distinct critical GPRS: “form a special task force to provide support in maneuvering COVID-19,” “provide infrastructure investment budgets to local governments,” “develop employee assistance programs that fit all types of working groups” and “diversify existing supply chain.” Large enterprises have two distinct critical GPRS: “provide help in digitalizing existing construction projects” and “mandate COVID-19 as force majeure.” Eighteen GPRS can be categorized into the following five constructs: “market stability and financial aid,” “enterprise capability management,” “supply chain improvement,” “law and policy resources” and “information and workforce management.” The former two constructs are more effective than other GPRS constructs.

This is the first paper that evaluates the effectiveness of GPRS for AEC enterprises, providing new evidence to policymakers for well-informed decision-making in developing pandemic response strategies.

Since the end of the 1990s, the Algerian public authorities have implemented research and innovation policies in order to build a solid National Innovation System (NIS) and improve industrial and economic performance. Today, the NIS remains immature, which hinders the learning and innovation processes. Our objective here is to analyze under a broad vision the Algerian NIS by examining its various components, to evaluate the capacities of training and innovation, and to measure the production of the innovation and the economic performances. Our research question is the following: How could the Algerian public authorities build a solid NIS in order to improve economic performance? To answer this question, we use a research methodology that mobilizes three types of complementary indicators in order to analyze the processes of learning and innovation from a systemic and interactive perspective. We also use economic performance indicators in order to put the analysis into a broader perspective. At the end, we propose action policies in favor of the construction of a complete Algerian NIS to improve economic performance.

The purpose of this study is to examine the benefits and challenges of using logistics service providers (LSPs) for small and medium-sized enterprises (SMEs) and large corporations.

This study uses the focus group interview method with eight LSP companies of varying sizes in the UAE. The aim is to obtain detailed insights into the advantages and obstacles associated with using LSPs.

The interview results reveal differences in the services and payment options offered by large and small-medium-sized LSPs, leading to varying impacts on SMEs. Additionally, both large and small-medium-sized LSPs encounter challenges in delivering services to SMEs, including sustaining logistic excellence in a competitive market, meeting the high customer expectations from SMEs and large enterprises, difficulty in recruiting skilled and competent employees and high costs of business technology.

This study is limited to the UAE context and the perspectives of eight LSP companies. The findings may not be generalizable to other regions or industries.

The findings of this research provide valuable insights for SMEs and large corporations considering the use of LSPs. Understanding the benefits and challenges associated with outsourcing logistics services can assist in making informed decisions and developing effective collaborations with LSPs.

This research contributes to the existing literature by specifically examining the benefits and challenges of using LSPs for SMEs and large corporations. This study provides a comprehensive analysis of the factors that influence logistics outsourcing decisions and highlights the unique challenges faced by LSPs and SMEs in the context of the UAE.

The purpose of this study is to propose a fast method for predicting flow fields with periodic behavior with verification in the context of a radial turbine to meet the urgent requirement to effectively capture the unsteady flow characteristics in turbomachinery. Aiming at meeting the urgent requirement to effectively capture the unsteady flow characteristics in turbomachinery, a fast method for predicting flow fields with periodic behavior is proposed here, with verification in the context of a radial turbine (RT).

Sparsity-promoting dynamic mode decomposition is used to determine the dominant coherent structures of the unsteady flow for mode selection, and for flow-field prediction, the characteristic parameters including amplitude and frequency are predicted using one-dimensional Gaussian fitting with flow rate and two-dimensional triangulation-based cubic interpolation with both flow rate and rotation speed. The flow field can be rebuilt using the predicted characteristic parameters and the chosen model.

Under single flow-rate variation conditions, the turbine flow field can be recovered using the first seven modes and fitted amplitude modulus and frequency with less than 5% error in the pressure field and less than 9.7% error in the velocity field. For the operating conditions with concurrent flow-rate and rotation-speed fluctuations, the relative error in the anticipated pressure field is likewise within an acceptable range. Compared to traditional numerical simulations, the method requires a lot less time while maintaining the accuracy of the prediction.

It would be challenging and interesting work to extend the current method to nonlinear problems.

The method presented herein provides an effective solution for the fast prediction of unsteady flow fields in the design of turbomachinery.

A flow prediction method based on sparsity-promoting dynamic mode decomposition was proposed and applied into a RT to predict the flow field under various operating conditions (both rotation speed and flow rate change) with reasonable prediction accuracy. Compared with numerical calculations or experiments, the proposed method can greatly reduce time and resource consumption for flow field visualization at design stage. Most of the physics information of the unsteady flow was maintained by reconstructing the flow modes in the prediction method, which may contribute to a deeper understanding of physical mechanisms.

This paper aims to explore how teachers’ choice of text, centering of student voices and collaboration with the community around a language arts curriculum impacted the engagement and learning experiences of 85 11th and 12th-grade refugee background students designated as English language learners.

A qualitative self-study framework that inquired into the assumptions about teaching and learning and the roles as social justice educators framed this narrative paper. Student journaling and teachers’ reflection logs and observations of class dramatization during a lesson unit on the play Les Blancs by Lorraine Hansberry formed the research text and informed the thematic analysis and findings of this study. The lenses of culturally sustaining pedagogy and a third space helped unpack the vantages of student voice and community engagement in the curriculum.

In a unit whose central text was chosen based on students’ racial and ethnic identities and their interests, they actively engaged in class and role-played as teachers, generating content that fostered their linguistic repertoires and critical discussions in class. Collaboration with community partners boosted the teacher’s agency with the curriculum and created a model of collaboration and learning for the class.

Student voices and community engagement in learning are powerful tools for designing culturally sustaining pedagogies.

This study aims to explore the formation mechanism of aerodynamic noise of a high-speed maglev train and understand the characteristics of dipole and quadrupole sound sources of the maglev train at different speed levels.

Based on large eddy simulation (LES) method and Kirchhoff–Ffowcs Williams and Hawkings (K-FWH) equations, the characteristics of dipole and quadrupole sound sources of maglev trains at different speed levels were simulated and analyzed by constructing reasonable penetrable integral surface.

The spatial disturbance resulting from the separation of the boundary layer in the streamlined area of the tail car is the source of aerodynamic sound of the maglev train. The dipole sources of the train are mainly distributed around the radio terminals of the head and tail cars of the maglev train, the bottom of the arms of the streamlined parts of the head and tail cars and the nose tip area of the streamlined part of the tail car, and the quadrupole sources are mainly distributed in the wake area. When the train runs at three speed levels of 400, 500 and 600 km·h⁻¹, respectively, the radiated energy of quadrupole source is 62.4%, 63.3% and 71.7%, respectively, which exceeds that of dipole sources.

This study can help understand the aerodynamic noise characteristics generated by the high-speed maglev train and provide a reference for the optimization design of its aerodynamic shape.