Variation Of Design Parameters Research Articles

Prediction of the undrained base heave and post uplift in braced excavation of a typical subway station in thick soft clay

Construction of a typical subway station usually involves a narrow long excavation with a width of approximately 20 m. An undrained base heave is a common problem in deep excavation areas with soft clay, which may induce considerable post uplift and damage the safety of the retaining system. Post uplift involves complex interactions between soil, pile post foundation, and supported struts, and an accurate prediction of post uplift is challenging. This paper aimed to establish a practical method for predicting the base heave and post uplift in the construction of typical subway stations in areas with thick soft clay. Series soil–water coupled finite element method (FEM) analysis was conducted to investigate the characteristics of the base heave with different soil properties and wall stiffnesses. The results showed that the calculated base heave can be fitted by a normalized function, regardless of large variations in soil properties and wall design parameters. The normalized function was then applied to a soil–post–strut interaction analysis model to predict the post uplift at different excavation depths. The application of the proposed method to a real subway station project showed that the predicted results were in good agreement with the field observations.

Analysis of CdS/CdTe Thin Film Solar Cells as a Function of CdS Doping Concentration: A Numerical Simulation Perspective

Cadmium Telluride (CdTe) photovoltaics, incorporating a thin film of Cadmium Sulfide (CdS), present a costeffective yet less efficient solar cell technology. Improving CdS/CdTe solar cell efficiency involves optimizing parameters like doping concentration and CdS layer thickness. However, limited research on cell defects necessitates a comprehensive analysis, including the often-overlooked impact of temperature. This study aims to analyze defect-free and defective CdS/CdTe solar cells, exploring the effects of doping concentration and other parameters. Using the SCAPS-1D simulator, design parameter variations will be investigated, and key metrics— open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and efficiency (η)—will be extracted. Simulation results indicate minimal efficiency impact from increased doping concentration in the ntype CdS layer for defect-free devices. The optimal doping concentration for CdS is 5 × 10<sup>18</sup> cm<sup>-3</sup>, with an optimum electron affinity of 4.0 eV. CdS thickness shows no significant efficiency impact, with the chosen optimum at 10 nm. In the defect-free CdS/CdTe solar cell, key metrics were Voc: 1.06 V, Jsc: 24.60 mA cm<sup>-2<sup>, FF: 87.89%, and η: 23.01%. Analysis of defects revealed single acceptor defects significantly impacting solar cell performance in both interfacial and bulk defects. Defect structure simulations demonstrated that increasing doping concentration, decreasing electron affinity, and thickness enhance efficiency. New optimum values for these parameters—1 × 10<sup>18</sup> cm<sup>-3</sup>, 4.0 eV, and 10 nm—yielded Voc: 1.03 V, Jsc: 23.88 mA cm<sup>-2</sup>, FF: 87.15%, and η: 21.40%. Additionally, a temperature decrease was associated with increased efficiency.

Multi-injection downdraft moving bed reactor for hydrolysis in thermochemical hydrogen production

This paper investigates a downdraft multi-injection moving bed reactor (MBR) for the hydrolysis reaction in the copper-chlorine (Cu–Cl) thermochemical cycle for hydrogen production. The numerical modelling is conducted for a variety of system configurations of the MBR, with a focus on reducing the energy requirement of the reactor while achieving high conversion rates. Several design variables are investigated, including reactor volume, injection point location, and quantity of steam injection. The numerical predictions show an approximate 23% increase in CuCl2 conversion for the multi-injection MBR compared to a single injection design. A maximum conversion of 66.5% is predicted through design parameter variations. Asymptotic behavior for the quantity of injection locations with respect to conversion extent is presented for several different steam to copper ratios. The results and new insights in this paper suggest opportunities for conversion improvement and steam to copper ratio reduction in the hydrolysis reactor through the MBR design.

Dynamic simulation and performance analysis of a solid-state barocaloric refrigeration system

Barocaloric refrigeration technology is a promising candidate for next-generation refrigeration technologies attributed to its eco-friendliness, high efficiency, and mechanical stability. To date, research in this field has predominantly focused on the exploration of solid-state refrigerants. However, the development of barocaloric systems is currently hindered by a lack of both prototype models and a comprehensive theoretical foundation. Addressing this gap, this study innovatively introduces the first model of a barocaloric refrigeration system, characterized by efficient hydrostatic pressure transitions and rapid heat and cold extraction. The employed refrigerant, neopentyl glycol, is notable for its low cost and significant barocaloric effect. Through the development of a one-dimensional dynamic numerical model for the system, this study investigates the system's temperature variability and operational efficiency under varying design parameters and operating conditions. Simulations suggest that the system could achieve a maximum COP of 13.1 and a refrigeration capacity of 106.4 W at a temperature span of 10 K. Additionally, the system is capable of reaching a maximum temperature span of 18 K under no-load conditions. This research not only underscores the theoretical viability of barocaloric refrigeration, but also provide crucial theoretical support and guidance for the design and construction of the first-generation barocaloric refrigeration prototype.

Experimental investigation of varying design parameters on the production rate and temperature polarisation of a DCMD system

Much of the research in the analysis of Temperature polarisation (TP) and the productivity of a membrane distillation (MD) system tends to concentrate on operational conditions. However, substantial enhancements in permeate flux can be realised through the incorporation of fundamental design modifications. This research showed that TP can be successfully mitigated almost to a level of non-existence, by manipulating the module orientation and flow channel height of an in-house designed direct contact membrane distillation (DCMD) system. Notably, at higher flow channel heights, changing the module orientation from the default horizontal position with the feed side on top (FST) to a sideway orientation led to a remarkable 90% increase in the permeate flux of the DCMD module. Permeate side on top (PST) and sideways orientations performed significantly better than FST for larger channel heights, while at low channel heights, the improvement was slight. Temperature measurements proved that thermal convective currents and secondary flows played a vital role in assisting or opposing TP and cannot be disregarded when investigating the hydrodynamics of a DCMD system. The impact of flow directions was insignificant with different channel heights, while the proximity of the flow inlets played a pivotal role in shaping the temperature profiles along the membrane.

Design and simulation of a nano biosensor based on amorphous indium gallium zinc oxide (a-IGZO) thin film transistor

In this study, a biosensor utilizing a dielectric-modulated amorphous indium gallium zinc oxide (a-IGZO) thin film transistor (TFT) is introduced. TFT biosensors have garnered significant attention due to their heightened sensitivity, scalable nature, low power consumption, rapid electrical detection capabilities, and cost-effective means of mass production. By embedding a nano-cavity within the gate insulator of the TFT, biomolecules can accumulate within. As each biomolecule possesses its own dielectric constant, it modulates the effective gate capacitance and, subsequently, changes the channel conductance. To assess the sensitivity of the biosensor, variation in saturation current after the absorption of biomolecules with respect to the drain current in the case of an air-filled cavity has been considered as a precise measure. The efficient operation of a biosensor is contingent upon the sensitivity being highly dependent on the dielectric constant of the biomolecules that are accumulated within the nano-cavity. Consequently, a comprehensive evaluation has been conducted to ascertain the impact of critical design parameters which have the potential to affect the sensitivity of the biosensor. Additionally, a statistical analysis based on coefficient of variation measure has been performed to evaluate the susceptibility of the biosensor’s sensitivity to variations in geometrical and physical design parameters. The utilization of label-free detection methodology in this device presents a notable advantage due to its compatibility with the fundamental CMOS processing technology and its cost-effective potential for macro production.

Fault detection and identification in induction motor using weightless neural network.

This paper presents a novel multiclass, multiparameter real-valued weightless neural network-based classifier for fault detection and identification. In contrast to primitive variants of weightless neural nets, the proposed method is capable of multiclass identification with real-valued input features and has improved recognition and generalization capabilities. The major accomplishments of the proposed method include an improved input-to-address mapping strategy that is suitable for address assignment within discriminator units and an effective memory expansion scheme based on similarity metric-based membership value. The developed classifier is utilized for fault detection and identification in single-phase and three-phase induction motors. The sensitivity analysis of the method is investigated for design parameter variation and the fault diagnosis is performed for multiple faults of the motor. The proposed method achieves the highest accuracy of 99.6% and 89.25% for single-phase and three-phase induction motor fault identification, respectively.

Motion analysis of an undulatory fin underwater robot

ABSTRACT The underwater robot has gained increasing attention due to the crucial role of oceanographic surveys in monitoring and exploring resources. A bionic underwater robot offers several advantages, including enhanced environmental interaction, reduced noise, improved propulsion, a smaller turning radius, higher efficiency and greater stability. This study designs and investigates a bionic underwater robot featuring undulatory soft fins. Finite element analysis is used to compute the drag and velocity of the robot with various shape designs. Experiments are conducted to measure the velocity under varying design parameters, including kinematic parameters, hull geometric shapes and fin materials. The experimental results reveal that the Type I robot exhibits vertical oscillations that reduce its forward speed. This phenomenon may result from asymmetry between the top and bottom of the stern, generating a pitch moment that leads to lift and causes oscillation. It is also indicated from the experiments that velocity generally increases with amplitude and frequency. The robot achieves optimal velocity performance with a phase difference of 67.5° (0.375π) and an amplitude of 60° for both polyvinyl chloride and natural rubber fins. The robot with Type B at both ends performs better than the one with Type A at both ends, consistent with the finite element analysis results, though the difference is not significant in the current design. The shape design for the hull is crucial and warrants further investigation. This study provides recommendations for optimizing the shape, materials and motion parameters of bionic soft undulating fin underwater robots.

Transient analysis of laminated plates in thermal environment

Transient displacement of laminated plates under combined load based on Mantari' s displacement field are investigated. The solution is implemented under transient mechanical load (sinusoidal, step and triangular sinusoidal distributed pressures pulse) and thermal buckling for plates with different layer orientation and thickness ratio. Equations of motion based on higher-order theory are derived through Hamilton' s principle, and solved using Naviertype solution for simply supported laminated plates. The results are presented for many effective parameters such as the number of laminate and orientation on the dynamic response of plates. Results show the validity of this displacement field in studying response of laminated thick and thin plates under varied transient loading and design parameters.

Seismic behavior of precast columns with unbonded prestressed tendons and energy-dissipating bars: physical and numerical investigations

The study of the strength and failure modes of construction components has become increasingly important with the advent of industrialized construction. Recently, because of the need to promote the survivability of both structures and persons, it has encompassed failure modes associated with seismic threats. This study reports the seismic behavior of precast segmented columns designed with both unbonded prestressed tendons (UPTs) and energy-dissipating (ED) bars. A physical specimen was subjected to a quasi-static cyclic test; this permitted the evaluation of the damage mode and behavior of the energy dissipation mechanism, and permitted the establishment and verification of a fiber beam element simulation model. The model was then used to evaluate the effects of the variation of the design parameters on the behavior of precast assembled columns. The test specimen exhibited stable energy dissipation and a pinching effect during cyclic loading. An analysis using the fiber beam element model with varying design parameters revealed that high-strength concrete could mitigate the concrete damage and residual deformation after an earthquake, and that the concrete strength and steel bar strength should be matched when enhancing the seismic resilience of precast columns with high-strength steel bars. It was determined that increasing the prestress mechanism, namely the ratio of the UPTs, could greatly improve the residual deformation, while the ratio of ED bars is the key factor in enhancing the energy dissipation capacity of the precast columns. Suitable ratios of UPTs and ED bars are the keys to ensuring stable energy dissipation and low residual drifts. Moreover, an increased axial load ratio and prestress level are able to restrain the joint opening and improve the bearing capacity of the precast columns; however, an excessive axial load or prestressing force would result in the rapid degeneration of the carrying capacity and larger residual displacements.

Soft pneumatic actuator workspace augmentation with synthesis of simplified analytical and numerical subcomponent models

Chamber inflating soft pneumatic actuators (SPA) are widely used for many industrial applications. Despite the increasing popularity of the actuators, few analyses investigating the detailed functionality of the actuator subcomponents and the contribution of their functions to the overall actuator operation are available. Understanding the roles of the actuator’s (sub)components for the overall actuator motion is the fundamental motivation of this work. Consequently, this paper must evaluate the interactions between the actuator’s overall performance and the component-level design parameter variations. To understand the relation, this work builds component-level simplified analytical models and extends them to estimate the actuator motions. With finite element method (FEM) models, the work enhances its analysis of each component and confirms their contribution to the overall motion. Both the newly built analytical and FEM models are thoroughly compared to a series of experiments. Finally, the present work synthesizes the studied design sensitivity of the subcomponent variations and suggests a soft pneumatic actuator design that is believed to provide the maximum workspace.

Transmission accuracy–axial backlash–fatigue life-driven tolerance optimization of planetary roller screw mechanism

Abstract The planetary roller screw mechanism (PRSM) is an advanced linear transmission device. The relationship between tolerance allocation and performance risk still remains elusive, which is a challenge for its future applications. This work proposes a novel transmission accuracy–axial backlash–fatigue life-driven tolerance optimization method for the screw, roller, and nut of PRSM. A computational framework for PRSM transmission accuracy, axial backlash, and fatigue life calculation is developed to work on the parametric variation of design parameters including the eccentric, pitch, nominal diameter, and flank angle. Combinations of parametric variation are obtained by the Latin hypercube sampling-based tolerance statistical model to rapidly evaluate PRSM performance risk under operation conditions and tolerance parameters. The optimal tolerance parameters with the expanded width of tolerance interval and the minimum PRSM performance risk probability are obtained using the non-dominated sorting genetic algorithm. Results reveal that PRSM performance risk probabilities change from 89.25 to 68.72% and 58.1 to 56.86%, with 29.94 and 17.38% tolerance interval width increase under the high-precision and heavy-loading operation cases studied, respectively.

Emergent elasticity relations for networks of bars with sticky magnetic ends

Magneto-elastic materials have unique mechanical properties arising from the coupling between the magnetic and elastic components, which can be used in many engineering applications, such as waveguide systems, impact mitigation, and soft robotics. Traditional designs of magneto-elastic materials embed magnets or magnetic particles in a monolithic body. Under extreme conditions, the elastic matrices are prone to permanent damage and loss of functionality. An alternative framework was previously proposed by the authors in which 2D magneto-elastic networks were created through vibration-driven self-assembly from a dilute system of elastic bars with sticky magnetic ends. While these networks were demonstrated to fail gracefully under extreme loading and re-assemble under random excitation, how their emergent elasticity depends on magnet and elastic member characteristics remains to be fully understood. In this paper, to calculate the 2D bulk modulus of a given magneto-elastic network, particle dynamics simulations are first performed. An analytical framework is then developed to predict the bulk modulus of derived networks with varying design parameters, such as bar length and magnetic strength, based on the Cauchy–Born approximation. Through dimensional analysis, we demonstrate that 2D bulk modulus is linearly proportional to a composite variable that combines magnet strength, elastic member length, and wall thickness of the magnet holder, as evidenced by the collapse of 120 systems onto a single line. The numerical and analytical investigation of the bulk modulus of this architected magneto-elastic material demonstrates the broad tunability of its emergent elasticity, thereby enabling a myriad of promising applications of these systems.

Towards Understanding the Variation of Electrode Design Parameters on the Electrochemical Performance of Aluminum Graphite Batteries: An Experimental and Simulation Study

AbstractDue to their high power density and availability, aluminum batteries consisting of graphite positive electrode and ionic liquid electrolytes are promising candidates for post‐lithium‐ion batteries. However, the effect of the various electrode design parameters on their electrochemical performance is not well understood. Herein, a high‐fidelity physics‐based model validated with experimental data obtained from a Swagelok cell consisting of an aluminum metal negative electrode, imidazolium ionic liquid electrolyte, and graphite positive electrode is used to study the effects of various electrode design parameters on the discharge capacity. The model is used to optimize the design of the electrodes by generating several Ragone plots, estimating the optimum current density for a given cell design, and explaining the limitations of the cells based on the transport of the electroactive species. An optimum graphite thickness of 50 μm is obtained for all the discharge times considered in this study. Determining the ideal electrode configuration for Al‐graphite batteries using different ionic liquid electrolytes and considering various discharge durations could provide a reference point for evaluating the suitability of a specific ionic liquid electrolyte in a particular use case.

РАСЧЕТ ОСАДОК ПРОТЯЖЕННОГО ПЛИТНОГО ФУНДАМЕНТА КОНЕЧНОЙ ЖЕСТКОСТИ НА ОСНОВЕ ДАННЫХ КОМПЬЮТЕРНОГО МОДЕЛИРОВАНИЯ

The paper presents a database for estimation the magnitude of the settlement of an extended slab foundation of finite stiffness in the initial phase of projecting. The offered solution uses only interpolation methods without involving powerful computing devices. The computer program FEA, which formalises the finite element method, was used to obtain the result. The maximum horizontal and vertical dimensions of the computational schemes were 25H3•46H3. The computational scheme consisted of 57 500 finite elements in the form of right isosceles triangles conjugated at 29 106 nodes. The width of the stiffness matrix of the linear equation system was 466. This made it possible to eliminate the influence of trivial boundary conditions on the results. 560 computational operations were performed. It corresponded to the number of possible combinations of numerical values of the variables calculated parameters adopted in computer modelling of process of the slab foundation settlement. As an upshot of the computations, the authors made a table of coefficients of approximating expressions for the curves constructed from the results of the calculated dependences of slab foundation settlement on the variable design parameters. The article provides a calculation of settlements of two extended slab foundations of different widths, using a constructed database and interpolation methods. The control calculation in the FEA showed the difference between the values of the control settlements and the values obtained using the proposed tables and the linear interpolation method for 13.45 and 22.08 %. Summing up the results, the offered database can be used for preliminary (estimation) calculations of extended slab foundations settlements.

Parametric Study of the Hydrodynamic Characteristics of the Pumpjet Propulsor for the SUBOFF Submarine

Submarines with pumpjet propulsors have recently been used in many countries to improve their propulsion and noise performance. The pumpjet has the advantage of improving noise and cavitation performance by increasing the pressure inside the duct, and it has good efficiency at a low advance ratio. This study analyzed the propulsive performance of a pumpjet propulsor affixed to a SUBOFF submarine as a function of variations in the design parameters using computational fluid dynamics analysis. The incidence angle and camber of the duct and the pitch angle of the stator were selected as the design parameters. To investigate the propulsion performance as a function of the design parameter variations, each case’s thrust, torque, and efficiency were compared, and the velocity and pressure fields of each case were analyzed. In addition, the efficiency was analyzed using the non-dimensional mass flow rate and area ratio difference for each case. The duct incidence angle contributed most dominantly to the dimensionless flow rate and the difference in area ratio, and these two factors resulted in high efficiency at certain values. It is expected that further research will be conducted in the near future that takes into account cavitation inception speed and cavitation.

Life cycle assessment of demountable building elements: Influential design and use parameters

Demountable building is put forward as a solution to reduce the environmental impact of the construction sector. However, uncertainty on the actual environmental benefits that can be achieved, hinders its implementation. Life cycle assessment (LCA) can be used to measure the potential of demountable building. Variable design and use parameters, such as the number of use cycles and material lifespan, should be incorporated in LCAs of demountable building elements to account for different possible use scenarios. Existing LCAs of demountable elements only vary one parameter at a time and/or consider simple reuse scenarios and building elements. The aim of this paper is to show how LCAs of demountable building elements can be organized by focusing on influential design and use parameters, while resolving the limitations from existing research. The influence of the parameters is determined through a two-step sensitivity analysis executed for two types of building elements: space dividing walls and façade systems. First, parameters with a low influence are omitted through a screening sensitivity analysis. Then, the Sobol’ indices of the remaining parameters are calculated. The results show the influential parameters are the same for both types of building elements. Finally, an LCA with variable influential parameters for a demountable and non-demountable space dividing wall is conducted. According to a non-variable LCA, the non-demountable wall has the lowest environmental impact, but when considering variable parameters, the use scenarios for which the demountable wall has the lowest impact become clear, for example, when the wall is relocated every five years.

Research of the influence of design parameters of a vibrating conveyor on its technical characteristics

Purpose. The study is aimed at: determining the nature of the influence of design data on the technical characteristics of a two-pipe vibratory conveyor with an eccentric drive, in particular, the pipe diameter and drive power; building analytical dependencies of these values on the design characteristics: type and properties of the cargo, length of transportation, productivity; conducting a graphical analysis of the influence. Methodology. To achieve this goal, we used the calculation algorithms presented in the modern technical literature and analyzed the factors and values that affect the values of drive power and pipe diameter. It has been established that to determine the drive power of vibratory conveyors, it is necessary to carry out a detailed calculation, which includes: the angular velocity of the conveyor, the rotational speed of the eccentric shaft, the material transportation speed, the internal diameter of the pipe, the total mass of the oscillating system, the stiffness of the elastic system and the parameters of the springs, the forces in the connecting rod in the case of the resonant mode of operation and during the start-up period. Findings. For a two-pipe vibrating conveyor designed to transport a lead conglomerate, a graphical analysis of the influence of the length of transportation, productivity on the drive power and overall dimensions of the pipe was carried out. It was found that the function of the pipe diameter change with capacity is nonlinearly increasing (when other parameters are fixed), and the drive power with capacity is linearly increasing. Originality. The authors first studied the dependence of drive power and pipe diameter of a two-pipe vibrating conveyor with an eccentric drive on the lower pipe, and built analytical dependencies of technical characteristics (power and diameter) on design parameters: productivity, transportation length, type and physical and mechanical properties of the transported cargo. For a conveyor that transports lead sinter, graphical dependencies of the pipe diameter and drive power on the capacity and length of the conveyor were constructed. Practical value. The use of the constructed dependencies makes it possible to determine the general nature of the change in the above technical characteristics in the case of varying design parameters such as conveyor capacity and length. The proposed dependencies can be used to quickly determine the rational power of the conveyor drive for specific design data.

Effect of steel grid on enhancing seismic performance of bridge pier with low reinforcement ratio: Shaking table test and numerical simulation

The railway bridge piers with large cross section and low reinforcement ratio are easy to damage under earthquakes in China. The steel grid has been proved to be an effective strengthening method to improve the cyclic behavior using quasi-static test. In this study, shaking table tests were conducted to investigate the seismic response of three pier specimens. Experimental results indicated that the steel grid delayed the crack development and occurrence of uplifting-rocking phenomenon for the railway pier. For strengthened piers, about 7.5%-51.4% reduction, 9.1%-21.9% and 7.6%-27.4% enhancement is measured for displacement of pier top, acceleration of pier top and energy dissipation. To obtain the effect of design parameter variation of steel grid on seismic damage (i.e., the horizontal distance between steel grid and the surface of pier specimen, steel grid area and vertical spacing of steel grid), the numerical analysis mode of strengthened pier was established. The mechanical model of steel grid obtained by deriving the equivalent spring calculation method is used in the numerical simulation model. The results show that the horizontal distance variety between steel grid and surface of pier specimen has the most obvious impact to strengthening effect, while the vertical spacing of steel grid is the least. The smaller horizontal distance between steel grid and the surface of pier specimen, the higher steel grid area and shorter vertical spacing of steel grid are the most significant to reduce the different damage probability of the bridge pier.

Comparative evaluation of personalized 3D-printed scaffold-driven double-barrel fibula flap for the reconstruction of segmented mandibular defects

The challenge of reconstructing large mandibular bone defects with double-barrel fibula flap (DBFF) is limited by the availability of autogenous bone, which remains a significant issue in maxillofacial surgery. This study aims to compare the novel scaffold-driven double-barrel approach with the DBFF method, and investigate the biomechanical behavior of 3D-printed porous titanium scaffolds with varying design parameters. The mandibular reconstruction model underwent FEA in two surgery phases, under two experimental loads and two design parameters. The experimental scaffold design was categorized into 9 groups based on the porous diameters (DP = 4 mm, 5 mm, 6 mm) and strut diameters (DS = 0.4 mm,0.5 mm,0.6 mm). The results illustrated that the stress in fibula, cortical and trabecular bones for all groups were within the ranges of normal physiological levels. The porous scaffolds effectively transmit mechanical stimulation, resulting in bone graft materials achieving up to 99.9% strain, with low stiffness to avoid stress shielding. The study revealed that the design parameters of Group B and Group F were more conducive to meeting biomechanical demands and promoting bone regeneration. This study presents scientifically proven and effective clinical solution for restoring both function and aesthetics of mandibular defects, while also providing valuable insights for future design criteria in bone regeneration scaffolds.