Design Conditions Research Articles

Influence of Water Ingress at the Shield Tunnel Portal on Tunnel Deformation and Load Capacity Weakening

Abstract. During the construction of shield tunnels, adverse geological conditions can lead to tunnel segment settlement and damage. This study investigates the deformation patterns and changes in load capacity of shield tunnels under water ingress conditions at the portal, using a segment of the Jinan Metro as a case study. Through field measurements and numerical simulations, we analyzed the structural deformation and weakening of load capacity caused by water ingress. The results indicate that significant settlement occurs at both the tunnel crown and invert after water ingress, with a maximum settlement of 181.2 mm compared to the original design axis. The deformation profile of the tunnel primarily resembles a transverse "duck egg" shape, while the segments near the portal exhibit vertical "duck egg" deformations due to grouting and other factors. Multiple cracks and damages were observed in the segments, with up to 16 cracks found in a single ring. Compared to the original design conditions, the bending moment in the tunnel lining increased by approximately 7%, and the axial force increased by about 9%, leading to an 11% reduction in tunnel resistance effects. The findings of this study regarding tunnel lining deformation and load capacity weakening provide valuable insights for similar engineering projects.

Data-Driven Formation Control for Multi-Vehicle Systems Induced by Leader Motion

In this paper, a leader motion mechanism is studied for the finite time achievement of any desired formation of a multi-agent system. The approach adopted in this paper exploits a recent technique based on leader motion to the formation control problem of second-order systems, with a special effort to networks of mobile devices and teams of vehicles. After a thorough description of the problem framework, the leader motion mechanism is designed to accomplish the prescribed formation attainment in finite time. Both asymptotic and transient behavior are thoroughly analyzed, to derive the appropriate analytical conditions for the controller design. The overall algorithm is then finalized by two procedures that allow the exploitation of local data only, and the leader motion mechanism is performed based on data collected by the leader during a preliminary experimental stage. A final section of simulation results closes the paper, confirming the effectiveness of the proposed strategy for formation control of a multi-agent system.

Jewelry of Eastern Lanna Identity: Strategies and Approaches for Contemporary Jewelry Design from Cultural Identity

Today’s jewelry designs look more contemporary, emphasizing self-expression by reflecting the perspectives and ideas of designers and artists in the context of society, culture, ethnicity, aesthetics, technology and ways of life through designs that are unique and in line with today’s lifestyles to create new artistic approaches. This research presents strategies and guidelines for designing contemporary jewelry from cultural capital by using the eastern Lanna area as a case study. The researchers conducted a unique analysis by studying the image and identity of the provinces in the eastern Lanna region, which led to the development of strategies and guidelines for jewelry design that reflect the eastern Lanna identity, as well as assessment of the perceptions of and satisfaction with jewelry prototypes designed by these strategies and such guidelines. The results showed that, in this research, the BLEND strategy was used in contemporary jewelry design, which was developed from the interpretation of the identity, image and characteristics of the provinces in the eastern Lanna group, into a design development in the form of a mixed design, or hybridization. These guidelines for creative design have generated design terms and conditions to present the value of work that expresses identity through four elements, namely 1) color, 2) materials, 3) patterns/shapes, and 4) story contents, which are synthesized through the perception of representative images to design and produce jewelry prototypes. The results of the evaluation of the jewelry prototypes as a whole revealed that the jewelry can express the eastern Lanna identity in an effective way, resulting in the creation of new knowledge in design, which is the development of concepts and processes to interpret new meanings in design in order to create value and worth as part of the utilization of cultural capital in the development of the country.

Exploring the criterion for the self-pulsing suppression of mid-IR intracavity OPO with self-Raman scattering.

The stimulated Raman scattering (SRS) from the Nd:YVO4 gain medium is originally employed to eliminate the self-pulsing effect from the intracavity optical parametric oscillator (OPO) for achieving a continuous-wave (CW) mid-infrared output. The SRS with a second-order pump-wave power depletion is applied as the damping for the coupling between OPO pump-wave relaxation oscillation and signal-wave depletion. The SRS threshold conditions for different cavity and diode-pumped mode size designs are theoretically and experimentally explored. By using different resonators, the CW mid-infrared output from 120 mW to 1.56 W at the diode pump power from 3 to 19.3 W can be successfully demonstrated.

Performance improvement of a centrifugal compressor for cogeneration

This work presents the performance improvement of a centrifugal compressor designed for cogeneration applications. The study involves modifications to geometric parameters, including impeller and diffuser configurations, to enhance pressure ratio, temperature ratio, and overall efficiency using computational fluid dynamics to verify the improvement of those parameters. The study has examined the compressor’s behaviour under surge, design, and choke conditions, showcasing improved homogeneity, reduced low-velocity zones, and an extended operating range. The compressor maps are presented to graphically observe the impact of each proposed modification, facilitating the analysis of each of these and evaluating the performance under various operating conditions. The final compressor configuration exhibits notable improvements in key performance metrics, with pressure ratio, temperature ratio, and efficiency showing increases of 1.753%, 1.640%, and 1.760%, respectively.

Attack-Dependent Adaptive Event-Triggered Security Fuzzy Control for Nonlinear Networked Cascade Control Systems Under Deception Attacks

This article investigates the issue of H∞ security output feedback control for a nonlinear networked cascade control system with deception attacks. First, to further reduce the amount of communication data, reasonably schedule network resources, and alleviate the impact of multi-channel deception attacks, an attack-dependent adaptive event-triggered mechanism is introduced into the primary network channel, and its adaptive triggered threshold can be adjusted according to the random attack probability. Secondly, the output dynamic quantization of the secondary network channel is considered. Then, a novel security cascade output feedback controller design framework based on the Takagi–Sugeno (T-S) fuzzy networked cascade control system under deception attacks is established. In addition, by introducing the Lyapunov–Krasovskii stability theory, the design conditions of the controller are given. Finally, the effectiveness and superiority of the proposed design strategies are verified by two simulation examples of power plant boiler–turbine system and power plant boiler power generation control system.

Efficient and reliable corrosion control for subsea assets: challenges in the design and testing of corrosion probes in aggressive marine environments

Abstract This review discusses the challenges in designing and testing corrosion probes for aggressive marine environments. The objectives are to analyze existing literature, identify methodological problems, and highlight research gaps in subsea corrosion control. To achieve these, a comprehensive review of relevant literature was conducted, focusing on factors like high salinity, fluctuating temperatures, and the presence of corrosive agents. The methods involved synthesizing information from peer-reviewed articles, industry reports, and academic publications to thoroughly analyze current state of knowledge. The findings of this review highlight the need for standardized testing protocols, improved understanding of material compatibility, and consideration of real-world conditions in corrosion probe design and testing. Methodological problems include the lack of standardized testing protocols, limited understanding of material compatibility, and insufficient consideration of real-world conditions. These findings emphasize the challenges researchers and practitioners face in developing efficient and reliable corrosion control strategies for subsea assets. In terms of novelty and improvement, this manuscript contributes to improving corrosion control practices in aggressive marine environments by synthesizing existing literature, identifying methodological problems, and highlighting gaps. By addressing these challenges, future research can focus on developing innovative solutions and methodologies to enhance the durability and effectiveness of corrosion probes in subsea environments.

Modeling and Performance Analysis of Variable Cycle Engine with Ceramic Matrix Composite Turbine Blades

To meet the requirements of future aircraft for power systems, the turbine inlet temperatures of aero engines are gradually increasing. Ceramic matrix composite (CMC), with its higher thermal limit, has become the preferred material for the turbine blades of variable cycle engines (VCEs). However, the impact of CMC turbine blades on the performance of a VCE is still unknown. In this research project, the comprehensive cooling-efficiency characteristics of CMC are determined through a fluid–solid coupling calculation; a cooling calculation model for turbine blades is established, and cooling airflow solution and control technology (CSCT) for an air system is developed. Additionally, a VCE simulation model is established to analyze the influence of CMC turbine blades on the cooling airflow of the air system and the overall performance of the engine. The results show that, for the design condition, the CMC turbine blade can reduce the cooling airflow of the air system by approximately 10%, and the net thrust is increased by 6.07–7.98%. For the off-design conditions, with the CSCT, the specific fuel consumption can be reduced by 3.06–5.73% while ensuring that the engine net thrust remains unchanged. A comprehensive analysis of the performance for both the design point and off-design points indicates that the use of CMC for high-pressure turbine (HPT) guide vanes and rotor blades yields significant performance benefits, while the performance improvement from the use of CMC for low-pressure turbine (LPT) rotor blades is minimal.

Thermo-economic analysis on trans-critical compressed CO2 energy storage system integrated with the waste heat of liquid-cooled data center

Compressed CO2 energy storage (CCES) technology has the advantages of high energy storage density, low economic cost, low carbon emission, which is suitable for the construction of large-scale and long-time energy storage system. Besides, as a scene with massive heat, the electricity consumption of servers in data center is mostly converted into heat. Thus, the purpose of this work is to integrate a trans-critical compressed CO2 energy storage system with the waste heat of data centers, so as to improve the system performance and reduce the operating cost of data center. Based on different operating principles of compressors, a single-stage compression system (System-CP) and a double-stage compression system (System-VP) are constructed. To analyze and compare the energy and exergy performance of these two systems under design conditions, a quasi-dynamic model is developed by considering the variations of pressure and temperature in the storage tank. On this basis, an economic model is developed to obtain the economy performance for the systems. The obtained results show that the round-trip efficiency (RTE) of System-CP and System-VP are 64.67 % and 67.41 %, respectively. For the energy storage capacity 15 MW × 5 h, volumes of high-pressure S-CO2 storage tank are 314,387.51 m3 and 287,982.91 m3 for System-CP and System-VP, respectively. Thereby, the energy storage density (ESD) of System-CP and System-VP are 0.24 kW·h/m3 and 0.26 kW·h/m3, respectively. Meanwhile, the total capital cost (TCC) is $477.84 × 106 for System-CP, and $437.41 × 106 for System-VP, and the corresponding payback period (PBP) are 14.76 years and 12.39 years respectively. Further, the effect of key parameters on systems performance is revealed. The results show that with the decrease of slip-pressure range decreases, RTE, TCC and the volume of storage tanks increase linearly.

Development and performance evaluation of a novel solar mid-and-low temperature receiver/reactor with packed metal foam

Solar-driven hydrogen production from methanol decomposition (MD) is an important method of storing solar energy as clean fuels and improving the solar energy utilization efficiency. Catalyst preparation is one of the key steps, but conventional Cu-ZnO-Al2O3 particle catalysts lead to uneven reactor temperature, reducing the efficient conversion of solar energy into fuels. To alleviate this challenge, a monolithic catalyst utilizing packed foamy copper as a carrier is developed with exceptional thermal and mass transfer properties. The experimental results validate its excellent performance in hydrogen production using MD. The absolute conversion increases by an average of 12.11 % at 250 °C and further by 14.43 % at 270 °C compared to the particle catalyst. Based on these findings, a novel solar reactor is proposed, and a multi-field coupling model is built. The comparative results verify the performance advantage of the developed solar thermochemical receiver/reactor with packed metal foam-based catalyst. It maintains high conversion rates and solar-to-fuel energy efficiency, while alleviating overheating problems caused by traditional particle catalysts. Under the design conditions, the new reactor significantly improves the absolute conversion of methanol and the energy efficiency of solar-to-fuel conversion by 4.57 % and 3.00 %, respectively, resulting in 92.64 % and 67.56 %. This study provides a theoretical basis and technical solution for more stable and efficient use of mid-and-low temperature solar energy.

Experimental Study of an Industrial Data Transmission Network in the Automatic Control System of a Wind Turbine

This article explores and optimizes network technologies for wind energy systems, focusing on the RS-485 interface to ensure reliable data transmission in extreme conditions. The study aims to address the impact of various distortions on data quality and wind turbine management. A system was proposed with two wind turbines, each equipped with a Raspberry Pi 4, connected to sensors measuring temperature, vibration, and wind speed. The research examined how data transmission rates affect signal shape, calculating the distortion coefficient. At 460,800 baud, the signal was almost completely distorted, with significant amplitude loss. The distortion coefficients were 1.84 for logic ‘1’ and 1.92 for logic ‘0’. The optimal speed to minimize distortions was found to be 19,200 baud, providing the most stable signal. Additionally, temperature significantly impacted transmission quality, highlighting the need to consider climatic conditions in system design. The findings and methods can help improve existing data transmission systems and enhance wind turbine performance.

Mixing enhancement with minimal thrust loss for the Mach 1.76 jet issuing from different beveled collar nozzles

The main objective of the present investigation is to enhance the jet mixing by introducing a nozzle collar exit inclination having bevel angles of 30°, 45°, and 60°. In addition to this, the present study also addresses the problem of investigating the jet which attains maximum mixing from beveled collar nozzle with the imposition of a minimal overall thrust loss penalty. The nozzles of the present study have been designed to deliver a uniform Mach 1.76 jet at the nozzle collar exit. The results thus obtained through numerical computations have been compared with that of the reference nozzle which has zero exit inclination. The investigations have been performed under both design and off-design conditions of the jet by varying the nozzle pressure ratio (NPR) from 4.5 to 6.5 with unit step size. It is seen that the rate of jet mixing is augmented with the increase in the bevel angle. Thus, the 60° beveled collar nozzle demonstrated the highest jet mixing in comparison to the reference nozzle, 30° and 45° beveled collar nozzle at each nozzle pressure ratio. However, 60° beveled collar nozzle has been substantially penalized with the highest thrust loss of about 6.5% at nozzle pressure ratio 4.5 and about 3.5% at nozzle pressure ratio 5.5 with respect to the reference nozzle and other nozzles of the present study. The 45° and 30° beveled collar nozzles reported the thrust penalty below 2.3% and 1%, respectively. The overall performance, which includes mixing enhancement along with the minimal thrust loss, has been found in the 45° beveled collar nozzle, which clearly justifies its preference over the other investigated nozzle configurations.

Adaptive Event-Triggered Consensus Control of Nonlinear Multi-Agent Systems via Output Feedback Methodology: An Application to Energy Efficient Consensus of AUVs

For dealing with the energy consumption in multi-agent systems (MASs), an event-triggered (ET) methodology is promising, which relies on the activation of communication devices only when communication of data is needed. This paper explores the leaderless consensus for nonlinear MASs using an adaptive ET approach via an output feedback methodology. This adaptive ET scheme is preferred as it can adapt to the environment through setting a communication threshold. The proposed approach renders the observed states of agents by use of nonlinear observers in an output feedback control dilemma, making it more practical. Simple Luenberger observers are developed to avoid the problem of always measuring agents’ states. The strategy of adaptive ET-based control is employed to minimize resource use and information transmission. Design conditions for the observer-based adaptive ET consensus control of nonlinear MASs have been derived via a Lyapunov function, containing state estimation error, consensus error, adaptation term, and nonlinearity bounds. In contrast to the existing methods, the present approach applies a more practical output feedback schema, uses adaptive ET proficiency, and deals with nonlinear agents. An example of a formation of autonomous underwater vehicles achieving the basic consensus realization between displacement and velocity is included to illustrate the viability of the resultant approach.

Combined Freak Wave, Wind, and Current Effects on the Dynamic Responses of Offshore Triceratops

Offshore structures are exposed to various environmental loads, including extreme and abnormal waves, over their operational lifespan. The existence of wind and current can exacerbate the dynamic response of these structures, posing threats to safety and integrity. This study focuses on the dynamic responses of offshore triceratops under different environmental conditions characterized by the superimposition of freak waves, uniform wind, and current. The free surface profile of the freak wave was generated using the dual superposition model. The numerical model of the offshore platform designed for ultra-deep-water applications was developed using the ANSYS AQWA 2023 R2 modeler. Numerical investigations, including the free decay tests and time-domain analysis under random sea states, including freak waves, were initially carried out. Then, the combined effects of freak waves, wind, and current were studied in detail under different loading scenarios. The results revealed the increase in structural response under the freak wave action at the focus time. Wind action resulted in a mean shift in responses, while the inclusion of current led to a pronounced increase in the total response of the platform, encompassing deck and buoyant legs, alongside the tether tension variation. Notably, considerable variations in the response were observed after freak wave exposure under the combined influence of wind, freak wave, and current. The results underscore the profound effects induced by wind and current in the presence of freak waves, providing valuable insights for analyzing similar offshore structures under ultimate design conditions.

Model predictive control for space robot manipulator modeled by switched systems: A data‐driven approach

AbstractThis article investigates the data‐driven based model predictive control (MPC) problem for a class of space robot manipulator (SRM). First, the SRM system is modeled as a class of discrete‐time switched system to reflect more system characteristics. Second, only the input‐state data are used for end‐to‐end controller design, and the system identification process is avoided. In order to meet the real‐time requirements of the manipulator arm angles, a kind of constrained predictive control method is designed to prevent the overheating or damage of SRM motor, optimizing the cost function for each decision cycle under the safe control input constraints. Then, based on the average dwell time method, the asymptotic stability is assured for the presented SRM system. The design conditions for data‐driven based MPC are provided in the form of linear matrix inequalities. Finally, the effectiveness and advantage for the developed data‐driven based MPC strategy are validated via a case study of SRM system.

Unravelling the nice-to-have and must-have circular economy-oriented dynamic capabilities for sustainable product design and end-of-life management: Insights from PLS-SEM and NCA

Drawing on the dynamic capabilities theory, a multi-method approach was used to examine the effects of circular economy-oriented dynamic capabilities on sustainable product design and end-of-life management. Partial Least Squares Structural Equation Modelling (PLS-SEM) and Necessary Condition Analysis (NCA) were employed on survey data from 285 manufacturing firms in Ghana. The findings show that whereas reconfiguring capabilities enhance sustainable end-of-life management, sensing and seizing capabilities were not direct predictors of sustainable end-of-life management. Nonetheless, sustainable product design was found to be a mechanism through which sensing and seizing capabilities promote sustainable end-of-life management. Also, apart from reconfiguring capabilities, sensing and seizing capabilities were positive predictors of sustainable product design. The NCA results suggest that all three circular economy-oriented dynamic capabilities (i.e., sensing, seizing, and reconfiguring capabilities) are must-have (necessary) conditions for sustainable product design and end-of-life management. We provide empirical evidence (via PLS-SEM and NCA) of the nice-to-have and must-have circular economy-oriented dynamic capabilities for sustainable product design and end-of-life management, besides highlighting sustainable product design as a mechanism through which these capabilities enhance sustainable product design.

Efficiency improvement and pressure pulsation reduction of volute centrifugal pump through diffuser design optimization

To investigate the effects of load distribution parameters of the diffuser vanes on the efficiency and pressure pulsation of the volute centrifugal pump, the diffuser shape was designed using an inverse design method, and an optimization method was proposed for the diffuser blade load distribution based on the combination of Latin hypercubic sampling, artificial neural network, and non-dominated sorting genetic algorithm-II. Steady and unsteady simulations were performed by solving the three-dimensional Reynolds-averaged Navier–Stokes equations using the shear stress transport k−ω turbulence model. The results obtained from Pearson correlation analysis revealed that the slope values Ks and Kh of the shroud and hub load distribution curves had the most significant effect on the pump head and efficiency. Compared with those of the original model, the efficiency and head of the optimized volute centrifugal pump under the design conditions increased by 3.8 and 3.5 %, respectively. The pressure pulsation intensities in the vaneless regions were effectively mitigated for the optimized volute centrifugal pump. The pressure pulsation coefficients at three times the diffuser vane frequency (3fDIF) reduced by 58.5 and 43.8 % at monitoring points M1 and M2, in the impeller outlet, respectively. The pressure pulsation coefficients at the impeller blade passing frequency (fBPF) reduced by 6.5 and 14.4 % at monitoring points M3 and M4 in the diffuser inlet, respectively. The results showed that the optimized diffuser improved the overall performance of the volute centrifugal pump, and demonstrated the feasibility of the optimization method.

Feasibility evaluation of a wind/P2G/SOFC/GT multi-energy microgrid system with synthetic fuel based on C-H-O elemental ternary analysis

Power to gas (P2G) uses electrical energy from access renewable power and captured carbon dioxide (CO2) to generate methane (CH4). The technology provides opportunity for replacing fossil fuels with green-powered hydrocarbon, benefiting the reducing of carbon emission. However, the methanation process in P2G requires high H2/CO2 ratio with available amount of hydrogen (H2) restricted by fluctuation of renewable power, bringing limits to the reusing of captured CO2. This paper presents a feasibility analysis of a novel wind/P2G/SOFC/GT multi-energy system (MES) for microgrid. Green-powered CH4 generated from P2G is mixed with captured CO2, bringing additional flexibility to balancing the overall H2/CO2 ratio for utilization. To comprehensively analyze the feasibility of synthesis CH4/CO2 fuel, evaluation of MES is carried out from both design and off-design conditions. For the design condition, a methodology of C-H-O elemental ternary analysis is applied to reflect the process of fuel utilization and reveal its connection with the trade-off feature of multiple components. For the off-design condition, fluctuations of user's load and renewable source during winter and summer scenarios are considered in a case study. Results show that under C-H-O distribution of 5.8 %, 61.2 % and 33.0 %, the SOFC/GT could operate safety with electrical efficiency of 62 %, capable of participating as a secondary power source for MES. Meanwhile, the overall H2/CO2 utilization ratio of the system is reduced from 4:1 to 2.4:1, where extremes conditions during winter and summer scenarios are evaluated with renewable penetration level of 94 % and wind curtailment rate below 5 % reached.

Modeling and Performance Analysis of Solid Oxide Fuel Cell Power Generation System for Hypersonic Vehicles

Advanced airborne power generation technology represents one of the most effective solutions for meeting the electricity requirements of hypersonic vehicles during long-endurance flights. This paper proposes a power generation system that integrates a high-temperature fuel cell to tackle the challenges associated with power generation in the hypersonic field, utilizing techniques such as inlet pressurization, autothermal reforming, and anode recirculation. Firstly, the power generation system is modeled modularly. Secondly, the influence of key parameters on the system’s performance is analyzed. Thirdly, the performance of the power generation system under the design conditions is simulated and evaluated. Finally, the weight distribution and exergy loss of the system’s components under the design conditions are calculated. The results indicate that the system’s electrical efficiency increases with fuel utilization, decreases with rising current density and steam-to-carbon ratio (SCR), and initially increases before declining with increasing fuel cell operating temperature. Under the design conditions, the system’s power output is 48.08 kW, with an electrical efficiency of 51.77%. The total weight of the power generation system is 77.09 kg, with the fuel cell comprising 69.60% of this weight, resulting in a power density of 0.62 kW/kg. The exergy efficiency of the system is 55.86%, with the solid oxide fuel cell (SOFC) exhibiting the highest exergy loss, while the mixer demonstrates the greatest exergy efficiency. This study supports the application of high-temperature fuel cells in the hypersonic field.

Mechanically Stabilized Earth Wall Reliability Analysis Using Response Surface Methodology, ANN, ANFIS and Multi-objective Genetic Algorithm

Considering uncertainty in the analysis of geotechnical structures is a necessary condition for optimal and robust design. An alternative method for studying the reliability of a mechanically reinforced earth wall in granular soil is used to account for these uncertainties more rigorously. This allows for the inclusion of various uncertainties in a mathematical risk formulation based on random variables. The deterministic model is a benchmark taken from the literature used in a numerical simulation to determine the maximum horizontal displacement of the wall. In this case, the serviceability limit state is considered, allowing the wall's actual behavior to be described. ANOVA was used to identify the most influential parameters on the system's response. As uncorrelated random variables, only the parameters (E, φ and γ) were considered. The mathematical model serving as the limit state function was numerically predictedby three methods, response surface methodology (RSM), artificial neural network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS), and their predictive capacities were then compared. The results showed that the ANN model outperformed the RSM and ANFIS models regarding prediction. ANN models and multi-objective genetic algorithm (MOGA) are used to optimize the Hasofer-Lind reliability index. The analysis is then carried out by taking into account the various types of functions of parameter distributions, which allowed us to better appreciate the effects of the uncertainties and identify the set of parameters with a high incidence.