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The purpose of this paper is to present investigations on the significant influence of the tube material and fin density on fluid elastic instability and vortex shedding in a parallel triangular finned tube array subjected to water cross flow.

The experiment was conducted on finned tube arrays with a fin height of 6 mm and fin density of 3 fins per inch (fpi) and 9 fpi. A dedicated setup has been developed to examine fluid elastic instability and vortex shedding. Nine parallel triangular tube arrays with a pitch to tube diameter ratio of 1.78 were considered. The plain tube arrays, coarse finned tube arrays and fine finned tube arrays each of steel, copper and aluminium materials were tested. Plain tube arrays were tested to compare the results of the finned tube arrays having an effective tube diameter same as that of the plain tube.

A significant effect of fin density and tube material with a variable mass damping parameter was observed on the instability threshold. In the parallel triangular finned tube array subjected to water cross flow, a delay in the instability threshold was observed with an increase in fin density. For steel and aluminium tube arrays, the natural frequency is 9.77 Hz and 10.38 Hz, which is close to each other, whereas natural frequency of the copper tubes is 7.40 Hz. The Connors’ stability constant K for steel and aluminium tube arrays is 4.78 and 4.87, respectively, whereas it is 5.76 for copper tube arrays, which increases considerably compared to aluminum and steel tube arrays. The existence of vortex shedding is confirmed by comparing experimental results with Owen’s hypothesis and the Strouhal number and Reynolds number relationship.

This paper’s results contribute to understand the effect of tube materials and fin density on fluid elastic instability threshold of finned tube arrays subjected to water cross flow.

The objective of this study is to investigate the impact of longitudinal forces on extreme-long heavy-haul trains, providing new insights and methods for their design and operation, thereby enhancing safety, operational efficiency and track system design.

A longitudinal dynamics simulation model of the super long heavy haul train was established and verified by the braking test data of 30,000 t heavy-haul combination train on the long and steep down grade of Daqing Line. The simulation model was used to analyze the influence of factors on the longitudinal force of super long heavy haul train.

Under normal conditions, the formation length of extreme-long heavy-haul combined train has a small effect on the maximum longitudinal coupler force under full service braking and emergency braking on the straight line. The slope difference of the long and steep down grade has a great impact on the maximum longitudinal coupler force of the extreme-long heavy-haul trains. Under the condition that the longitudinal force does not exceed the safety limit of 2,250 kN under full service braking at the speed of 60 km/h the maximum allowable slope difference of long and steep down grade for 40,000 t super long heavy-haul combined trains is 13‰, and that of 100,000 t is only 5‰.

The results will provide important theoretical basis and practical guidance for further improving the transportation efficiency and safety of extreme-long heavy-haul trains.

Voltage source inverter-fed permanent magnet synchronous motors (VSI-PMSMs) are widely used in industrial actuation and mechatronic systems in water pumping stations, as well as in the traction of transportation systems (such as electric vehicles and electric trains or ships with electric propulsion). The dynamic model of VSI-PMSMs is multivariable and exhibits complicated nonlinear dynamics. The inverters’ currents, which are generated through a pulsewidth modulation process, are used to control the stator currents of the PMSM, which in turn control the rotational speed of this electric machine. So far, several nonlinear control schemes for VSI-PMSMs have been developed, having as primary objectives the precise tracking of setpoints by the system’s state variables and robustness to parametric changes or external perturbations. However, little has been done for the solution of the associated nonlinear optimal control problem. The purpose of this study/paper is to provide a novel nonlinear optimal control method for VSI-fed three-phase PMSMs.

The present article proposes a nonlinear optimal control approach for VSI-PMSMs. The nonlinear dynamic model of VSI-PMSMs undergoes approximate linearization around a temporary operating point, which is recomputed at each iteration of the control method. This temporary operating point is defined by the present value of the voltage source inverter-fed PMSM state vector and by the last sampled value of the motor’s control input vector. The linearization relies on Taylor series expansion and the calculation of the system’s Jacobian matrices. For the approximately linearized model of the voltage source inverter-fed PMSM, an H-infinity feedback controller is designed. For the computation of the controller’s feedback gains, an algebraic Riccati equation is iteratively solved at each time-step of the control method. The global asymptotic stability properties of the control method are proven through Lyapunov analysis. Finally, to implement state estimation-based control for this system, the H-infinity Kalman filter is proposed as a state observer. The proposed control method achieves fast and accurate tracking of the reference setpoints of the VSI-fed PMSM under moderate variations of the control inputs.

The proposed H-infinity controller provides the solution to the optimal control problem for the VSI-PMSM system under model uncertainty and external perturbations. Actually, this controller represents a min–max differential game taking place between the control inputs, which try to minimize a cost function that contains a quadratic term of the state vector’s tracking error, the model uncertainty, and exogenous disturbance terms, which try to maximize this cost function. To select the feedback gains of the stabilizing feedback controller, an algebraic Riccati equation is repetitively solved at each time-step of the control algorithm. To analyze the stability properties of the control scheme, the Lyapunov method is used. It is proven that the VSI-PMSM loop has the H-infinity tracking performance property, which signifies robustness against model uncertainty and disturbances. Moreover, under moderate conditions, the global asymptotic stability properties of this control scheme are proven. The proposed control method achieves fast tracking of reference setpoints by the VSI-PMSM state variables, while keeping also moderate the variations of the control inputs. The latter property indicates that energy consumption by the VSI-PMSM control loop can be minimized.

The proposed nonlinear optimal control method for the VSI-PMSM system exhibits several advantages: Comparing to global linearization-based control methods, such as Lie algebra-based control or differential flatness theory-based control, the nonlinear optimal control scheme avoids complicated state variable transformations (diffeomorphisms). Besides, its control inputs are applied directly to the initial nonlinear model of the VSI-PMSM system, and thus inverse transformations and the related singularity problems are also avoided. Compared with backstepping control, the nonlinear optimal control scheme does not require the state-space description of the controlled system to be found in the triangular (backstepping integral) form. Compared with sliding-mode control, there is no need to define in an often intuitive manner the sliding surfaces of the controlled system. Finally, compared with local model-based control, the article’s nonlinear optimal control method avoids linearization around multiple operating points and does not need the solution of multiple Riccati equations or LMIs. As a result of this, the nonlinear optimal control method requires less computational effort.

Voltage source inverter-fed permanent magnet synchronous motors (VSI-PMSMs) are widely used in industrial actuation and mechatronic systems in water pumping stations, as well as in the traction of transportation systems (such as electric vehicles and electric trains or ships with electric propulsion), The solution of the associated nonlinear control problem enables reliable and precise functioning of VSI-fd PMSMs. This in turn has a positive impact in all related industrial applications and in tasks of electric traction and propulsion where VSI-fed PMSMs are used. It is particularly important for electric transportation systems and for the wide use of electric vehicles as expected by green policies which aim at deploying electromotion and at achieving the Net Zero objective.

Unlike past approaches, in the new nonlinear optimal control method, linearization is performed around a temporary operating point, which is defined by the present value of the system’s state vector and by the last sampled value of the control input vector and not at points that belong to the desirable trajectory (setpoints). Besides, the Riccati equation, which is used for computing the feedback gains of the controller, is new, as is the global stability proof for this control method. Comparing with nonlinear model predictive control, which is a popular approach for treating the optimal control problem in industry, the new nonlinear optimal (H-infinity) control scheme is of proven global stability, and the convergence of its iterative search for the optimum does not depend on initial conditions and trials with multiple sets of controller parameters. It is also noteworthy that the nonlinear optimal control method is applicable to a wider class of dynamical systems than approaches based on the solution of state-dependent Riccati equations (SDRE). The SDRE approaches can be applied only to dynamical systems that can be transformed to the linear parameter varying form. Besides, the nonlinear optimal control method performs better than nonlinear optimal control schemes which use approximation of the solution of the Hamilton–Jacobi–Bellman equation by Galerkin series expansions.

This paper aims to investigate the responses of single piles and pile groups due to tunneling-induced ground movements in a two-layered soil system. The analyses mainly focus on the additional single pile responses in terms of bending moment, lateral deflection, axial force, shaft resistance and pile settlement. Subsequently, a series of parametric studies were carried out to better understand the responses of single piles induced by tunneling. To give further understanding regarding the pile groups, a 2 × 2 pile group with two different pile head conditions, namely, free and capped, was considered.

Using the PLAXIS three-dimensional (3D) software, a full 3D numerical modeling is performed to investigate the effects of ground movements caused by tunneling on adjacent pile foundations. The numerical model was validated using centrifuge test data found in the literature. The relevance of the 3D model is also judged by comparison with the 2D plane strain model using the PLAXIS 2D code.

The numerical test results reveal that tunneling induces significant displacements and internal forces in nearby piles. The magnitude and distribution of internal forces depend mainly on the position of the pile toe relative to the tunnel depth and the distance between the pile and the vertical axis of the tunnel. As the volume loss increases from 1% to 3%, the apparent loss of pile capacity increases from 11% to 20%. By increasing the pile length from 0.5 to 1.5 times, the tunnel depth, the maximum pile settlement and lateral deflection decrease by about 63% and 18%, respectively. On the other hand, the maximum bending moment and axial load increase by about 7 and 13 times, respectively. When the pile is located at a distance of 2.5 times the tunnel diameter (Dt), the additional pile responses become insignificant. It was found that an increase in tunnel depth from 1.5Dt to 2.5Dt (with a pile length of 3Dt) increases the maximum lateral deflection by about 420%. Regarding the interaction between tunneling and group of piles, a positive group effect was observed with a significant reduction of the internal forces in rear piles. The maximum bending moment of the front piles was found to be higher than that of the rear piles by about 47%.

Soil is a complex material that shows differently in primary loading, unloading and reloading with stress-dependent stiffness. This general behavior was not possibly being accounted for in simple elastic perfectly plastic Mohr–Coulomb model which is often used to predict the behavior of soils. Thus, in the present study, the more advanced hardening soil model with small-strain stiffness (HSsmall) is used to model the non-linear stress–strain soil behavior. Moreover, unlike previous studies THAT are usually based on the assumption that the soil is homogeneous and using numerical methods by decoupled loadings under plane strain conditions; in this study, the pile responses have been exhaustively investigated in a two-layered soil system using a fully coupled 3D numerical analysis that takes into account the real interactions between tunneling and pile foundations. The paper presents a distinctive set of findings and insights that provide valuable guidance for the design and construction of shield tunnels passing through pile foundations.

This paper aims to help understand how community-based social entrepreneurs experience world-class “performance excellence” models and to explore the core values that enable social enterprises to become high-performance organizations.

Underpinned by Mindsponge processes, the proposed conceptual framework critiques the Baldrige criteria for performance excellence (BCPE) model in a global south context. The mixed-methods study fosters an in-depth analysis. First, it validates the BCPE mechanism in community-based social enterprises (CBSEs) before identifying the significant core values and concepts of BCPE that influence CBSEs to achieve high performance.

The BCPE, adapted from global north corporate principles and applied at a community level, can significantly develop global south organization performance excellence. Five core values and concepts from the 11 fundamental beliefs in driving performance excellence were found to support performance excellence in CBSE management. These values and concepts are “customer-focused excellence,” “social responsibility,” “systems perspective,” “visionary leadership” and “focus on success.”

First, factors influencing performance excellence are not limited to the core values elements discussed. Future research may clarify factors extracted from the “Process” category of BCPE to explore further how CBSEs can enhance their performance in a different formation path. Second, this study only considered the Thai-Phuan community in Pho Tak village, Nong Khai, Thailand, to represent as a single case study. However, different, clustered or contrasting CBSEs in other regions remain open for further exploration to enrich the knowledge of “performance excellence” in a community organization. Finally, a longitudinal study would be a welcome addition.

The following must be considered. First is setting a clear direction: the organization’s vision and mission, by purposeful design, should ensure that CBSE managers are leading by example and demonstrating the importance of social and environmental value creation. Second is developing institutional culture: fundamental core values focused predominantly on “customer-focused excellence” and “social responsibility” encourage collaboration by “working together to drive success”. Third is developing integrated management system: CBSEs need to ensure that the management systems can collaborate and complement each component to create performance excellence. Fourth is creating a learning organization: CBSEs need to create a culture of continuous learning through data collection, measurement, analysis and modification.

This study clarifies that the implementation of BCPE is crucial to the establishment of performance excellence at both macro- and micro-level organizations. According to the Malcolm Baldrige National Quality Award, the fundamental drivers of BCPE are the same for all types of organizations and in all sectors, whether in the private sector, education, health care or government (Blazey and Grizzell, 2021). By applying the Baldrige excellence model at the community level, this study found that CBSE can similarly strive for excellence and improved performance. This can lead to strengthened services, increased productivity and enhanced quality of life for the community.

This study provides a novel viewpoint on the Baldrige paradigm. Expressly, BCPE is compatible with global south community-based organizations to enhance performance excellence. Its essential contribution demonstrates that Baldrige model concepts are more widespread within smaller and underdeveloped territories than imagined. The recent (post-study) inclusion of “Community” as an independent sector in the Malcolm Baldrige National Quality Awards validates the research findings and recommendations proposed by this study.

This study aims to empirically examine the factors that affect mobile loyalty (m-loyalty) and its influence on customer reuse intention towards mobile instant messaging services. This study identified measurement items to assess the business users and individual users reuse intention towards mobile instant messaging services and test the relationship in the conceptual model. This study bridges a literature gap focusing on m-loyalty and its impact on customer reuse intention, which has not received attention previously.

To evaluate the influence of the factors, this study identified and extracted the items from past literature to develop the survey instrument. This study surveyed 600 respondents including business users and individual users from the Delhi-National Capital Region of India and applied the structural equation modelling to test the conceptual model.

The results revealed that satisfaction and m-loyalty have a direct effect on the business users and individual users’ reuse intention of mobile instant messaging services. This study found that satisfaction, usability, perceived value, commitment, trust and m-loyalty influence on business users reuse intention. This study indicate that enjoyment has an insignificant relationship on m-loyalty for business users followed by usability and enjoyment has an insignificant relationship on m-loyalty for individual users. Further, female gender does not moderate the relationship between satisfaction and business users reuse intention. The cognitive absorption and the unified theory of acceptance and use of technology (UTAUT) theories supported evaluating the association between the factors in the context of business and individual users reuse intention of mobile instant messaging service.

The empirical findings imply that all the factors except enjoyment have directly influenced the business users reuse intention of mobile instant messaging. The significant influence of usability factor on the business users reuse intention towards mobile instant messaging is the major variation between the validated models of business and individual samples. The results of influencing factors of m-loyalty and its impact on customer reuse intention are associated with cognitive absorption and the UTAUT theories.

Focus on these factors can be beneficial for the business users, managers, mobile instant messaging service providers and application developers to increase customer loyalty and reuse intention for the mobile instant messaging services. This research will facilitate mobile instant messaging service providers to keep their services market relevant and focus on user satisfaction in building applications for loyalty.

This research identified measurement items from earlier literature to identify, analyze and verify the relevance of these factors in m-loyalty and customer reuse intention of mobile instant messaging services and fill the gap in customer reuse intention of mobile instant messaging services literature.

Saudi Arabia's 2030 vision targets an increase of 34% in non-oil revenue participation in the GDP, thus the need for automation and digital transformation. The Company ER is a market leader producing high-quality dairy products in the Kingdom and is a pioneer in the production industry. The company has recently increased the capacity of its milk factory to meet its vision. An investment was made to automate the pallet handling procedures at the milk factory to provide increased production for daily consumption. The new automation transition in Company ER's milk factory provides a unique opportunity to utilize lean management tools to improve the current automated processes before commercialization.

OEE (overall equipment effectiveness) will monitor losses for different operational losses in the new automated system and indicate system improvements, with 85% as the target. Based on DMADV (design, measure, analyze, design and validate) methodology, this study analyzes the entire automated pallet handling system. It uses lean tools to identify areas for improvement, identify waste elements and propose solutions to achieve Company ER's OEE targets.

In this paper, the outcomes will be presented as documented solutions that address the losses encountered in the production system, showing a 12.8% increase in the system's OEE.

Owing the time and resource constraint, this study only involved automated pallet handling procedures in a milk production facility. Hence, the generalization of the result is slightly limited. More studies in several different processes and sectors are required.

This study provided a valuable tool for researchers for gaining deeper understanding regarding the lean manufacturing and its implementation. For practitioners, it is useful to evaluate the degree of lean manufacturing tools in their material handling systems.

This study is the first attempt to develop lean manufacturing constructs for evaluating the automated pallet handling procedures in a milk production facility.

Research in the business-to-business (B2B) and user entrepreneurship literature agrees that “user-driven” perspectives allow entrepreneurs to develop innovative products superior to conventional products. Other researchers argue that such “user-driven” products have limited success and limited impact in certain markets (e.g. niche and industrial markets). This study aims to understand the extent to which user input or co-creation becomes critical in determining product performance.

The key informant approach is used for data collection. Data were collected using a survey instrument via an online panel. Existing scales are used to measure all the focal constructs. Partial least square-based structural equation modeling was used to check for the psychometric properties of the scales and test the hypotheses.

The results indicate that user entrepreneurship is significantly related to firm collaboration efforts and customer collaboration efforts in the B2B market. Both firm collaboration efforts and customer collaboration efforts are significantly related to product performance and mediate the relationship between user entrepreneurship and product performance. Also, findings show that there is an “n” relationship between firm collaboration efforts and product performance.

This study supports the concerns raised by researchers about the dark side of value co-creation and highlights that value co-creation can impede product performance when user entrepreneurs lay too much emphasis on the collaboration processes.

This review provides an overview of recent advances in electrochemical sensors for analyte detection in saliva, highlighting their potential applications in diagnostics and health care. The purpose of this paper is to summarize the current state of the field, identify challenges and limitations and discuss future prospects for the development of saliva-based electrochemical sensors.

The paper reviews relevant literature and research articles to examine the latest developments in electrochemical sensing technologies for saliva analysis. It explores the use of various electrode materials, including carbon nanomaterial, metal nanoparticles and conducting polymers, as well as the integration of microfluidics, lab-on-a-chip (LOC) devices and wearable/implantable technologies. The design and fabrication methodologies used in these sensors are discussed, along with sample preparation techniques and biorecognition elements for enhancing sensor performance.

Electrochemical sensors for salivary analyte detection have demonstrated excellent potential for noninvasive, rapid and cost-effective diagnostics. Recent advancements have resulted in improved sensor selectivity, stability, sensitivity and compatibility with complex saliva samples. Integration with microfluidics and LOC technologies has shown promise in enhancing sensor efficiency and accuracy. In addition, wearable and implantable sensors enable continuous, real-time monitoring of salivary analytes, opening new avenues for personalized health care and disease management.

This review presents an up-to-date overview of electrochemical sensors for analyte detection in saliva, offering insights into their design, fabrication and performance. It highlights the originality and value of integrating electrochemical sensing with microfluidics, wearable/implantable technologies and point-of-care testing platforms. The review also identifies challenges and limitations, such as interference from other saliva components and the need for improved stability and reproducibility. Future prospects include the development of novel microfluidic devices, advanced materials and user-friendly diagnostic devices to unlock the full potential of saliva-based electrochemical sensing in clinical practice.