Influence Of Design Parameters Research Articles

Effect of alkali reactions on the rheology of one-part 3D printable geopolymer concrete

Yield strength development of 3D printable concrete by the early age activation reactions plays a vital role in the printability of geopolymer concrete. This study presents a rheo-chemical approach to investigate the early age strength development due to alkali reactions for the formulation of suitable 3D printable one-part geopolymer concrete. The influence of design parameters, including activator content, thixotropic additive (Magnesium Alumino Silicate -MAS), and retarder (sucrose) dosage, on the rheological properties of concrete were assessed. The shear stresses of geopolymer concrete were measured with the aid of a rotational rheometer for various shearing protocols that represent the major stages of printing operation (pumping, extrusion and building). The measured rheological properties were related to reaction kinetics of geopolymer mixes using FT-IR spectroscopy and calorimetry. The results revealed that, with MAS, activator and sucrose content of 0.75 wt%, 10 wt% and 1.5 wt% of the binder respectively, the formulated one-part geopolymer showcased enhanced printing properties. This is further demonstrated by printing laboratory-scale specimens and evaluating the hardened properties.

Theory and modeling of a novel class of nanoplate-based mass sensors with corner point supports

A novel class of nanoplate-based mass sensor with corner point supports for detecting attached nanoparticles is proposed. Exact solutions for vibrations of three types of nanoscale mass sensors are obtained by a symplectic superposition method combining with nonlocal elasticity theory. A comparison between theoretical prediction and FEM simulation is presented and excellent agreement is reported. Influences of design parameters on the frequency shift are investigated. Numerical results show that increasing magnetic field strength and environment temperature can effectively enhance the sensitivity of the mass sensor, and the nanoplate-based sensor point-supported at only one corner is the optimal design.

The DIOS framework for optimizing infectious disease surveillance: Numerical methods for simulation and multi-objective optimization of surveillance network architectures.

Infectious disease surveillance systems provide vital data for guiding disease prevention and control policies, yet the formalization of methods to optimize surveillance networks has largely been overlooked. Decisions surrounding surveillance design parameters—such as the number and placement of surveillance sites, target populations, and case definitions—are often determined by expert opinion or deference to operational considerations, without formal analysis of the influence of design parameters on surveillance objectives. Here we propose a simulation framework to guide evidence-based surveillance network design to better achieve specific surveillance goals with limited resources. We define evidence-based surveillance design as an optimization problem, acknowledging the many operational constraints under which surveillance systems operate, the many dimensions of surveillance system design, the multiple and competing goals of surveillance, and the complex and dynamic nature of disease systems. We describe an analytical framework—the Disease Surveillance Informatics Optimization and Simulation (DIOS) framework—for the identification of optimal surveillance designs through mathematical representations of disease and surveillance processes, definition of objective functions, and numerical optimization. We then apply the framework to the problem of selecting candidate sites to expand an existing surveillance network under alternative objectives of: (1) improving spatial prediction of disease prevalence at unmonitored sites; or (2) estimating the observed effect of a risk factor on disease. Results of this demonstration illustrate how optimal designs are sensitive to both surveillance goals and the underlying spatial pattern of the target disease. The findings affirm the value of designing surveillance systems through quantitative and adaptive analysis of network characteristics and performance. The framework can be applied to the design of surveillance systems tailored to setting-specific disease transmission dynamics and surveillance needs, and can yield improved understanding of tradeoffs between network architectures.

Influence of design parameters on flux‐weakening performance of interior permanent magnet machines with novel semi‐overlapping windings

This study performs a design and parametric study of interior permanent-magnet (IPM) machines equipped with novel semi-overlapping windings (NSWs). The influence of the key design parameters including; number of turns per phase, stack length, distance and angle between V-shaped magnets, rotor yoke thickness, magnetic bridge width and thickness and number of magnet segments on the flux-weakening (FW) performance characteristics are evaluated in detail. The influence of material of segmentation (material of bridge namely, air or iron) is also considered. A combination of analytical calculation-based program and a time-stepping 2D finite-element analysis based program are employed to evaluate the FW characteristics. The accuracy of the FW calculations, particularly the performance at high-speed regions, is verified over changes in torque components; namely reluctance and permanent magnet (PM), inductance components, PM flux coefficient and inverse saliency ratio due to the change in considered design parameter. The electromagnetic torque, torque ripple, output power and FW capability are investigated by parametric analyses. Moreover, the power losses and efficiency maps together FW curves are calculated for the optimal NSW IPM machine. The experimental measurements, taken from manufactured prototype, verify that the performed analyses and methods described in this study are accurate and reliable.

Design and experimental study of a mutual inductance displacement sensor for active magnetic bearings

A type of mutual inductance displacement sensor based on probe circuit board (PCB) technology is discussed in this paper. Firstly, the basic structure and principle of the sensor are introduced and an objective function of calculation is proposed for the optimisation of sensitivity. Then, the influence of design parameters on sensor performance is explored and some design experience is summarised. At the same time, a typical method of circuit implementation for the sensor is introduced and the static experiments are carried out with this method. Compared with the sensors reported in the literature, it is concluded that the index of the experimental sensor has reached a good level.

Assessing the thermal efficiency of energy tunnels using numerical methods and Taguchi statistical approach

The use of ground source heat pump systems (GSHPs) with tunnels (so-called energy tunnels) to provide space heating and cooling is one of the latest concepts that has recently raised research interest but has not yet been commercially established. This study represents the first attempt to investigate the influence of design parameters on the energy efficiency of a GSHP using an underground tunnel as the energy geostructure. Seven important design parameters, namely absorber fluid diffusivity, concrete diffusivity, pipe thermal conductivity, pipe diameter, length of pipe, pipe spacing and absorber pipe location were considered. The influence of these design parameters on the tunnel thermal efficiency was studied by using an experimentally validated 3-D numerical model and then deploying the Taguchi method to efficiently explore parameters space. The results show that concrete diffusivity and pipe total length are the most influential parameters, followed by the pipe location and diameter, while spacing was found to be the least influential factor. Hence the overall thermal output of an energy tunnel depends largely on the available area for heat exchange and the thermal properties of the tunnel lining. Results also show that within the range of pipe diameter considered, using a larger pipe diameter in energy tunnels is more efficient from the thermal output and pump power requirements. These results can be used as thermal efficiency optimisation guidance for both researchers and practitioners.

Coupled nonlinear-damage finite element analysis and design of novel engineered wood products made of oak hardwood

This paper presents a comprehensive experimental and numerical investigation to design novel engineered wood products (EWPs), namely adhesive-free laminated beams (AFLB) and adhesive-free cross-laminated timber (AFCLT) panels, for the first time. Thermo-mechanically compressed wood (CW) dowels were used as a joint element as an alternative to the traditional glue and metallic fasteners. The following structural elements were studied: (1) solid timber beams, (2) middle-scale and large-scale three-layer AFLB, (3) timber-to-timber connections and (4) AFCLT panels. In addition, a predictive coupled nonlinear-damage model was proposed as a predictive and powerful tool design to reduce expensive experimental tests. The main mechanical characteristics and performance of the designed EWPs are assessed experimentally and addressed in the paper. Furthermore, the accuracy and the performance of the developed FE model were verified against experimental results from the studied example showing a fairly good prediction of the non-linear behavior as well as the modes of failure and its growth. Finally, the validated FE model was used to carry out a parametric study of the influential design parameters and some design recommendations are made.

Prediction Mathematic Model and Influencing Factors of Contact Stress of Cylindrical Gear with Arc Tooth

Given the absence of a theoretical formula to analyze the influence of parameters on the contact stress of cylindrical gear with arc tooth, an explicit mathematical model of cylindrical gear with arc tooth between the design parameters and the contact stress is established based on Kriging surrogate model. The parameters of the variation function of Kriging model are optimized by using the whale optimization algorithm (WOA), and the explicit mathematical model accuracy between the design parameters and the contact stress of the gear is in turn optimized by the improved Kriging surrogate model. The influence of design parameters on the contact stress of cylindrical gear with arc tooth is analyzed based on the established mathematical model. The proposed algorithm was realized via the programming platform MATLAB; the simulation results indicate that the precision evaluation indexes (the correlation coefficient (R2), root mean square error (RMSE), and the relative maximum absolute error (RMAE)) of the proposed Kriging model are improved, in addition to the error range which is narrowed from (−2, 4) to (0, 3). As the tooth width, modulus, pressure angle, and tooth line radius increased, the contact stress of the cylindrical gear with arc tooth gear declined, which was negatively correlated with the design parameter. The amplitude of contact stress of the cylindrical gear with arc tooth was the largest due to the change of tooth radius, followed by the change of modulus, while the influence of tooth width was less. Finally, the influence of modulus-tooth line radius interaction and pressure angle-tooth line radius interaction on contact stress of cylindrical gear with arc tooth was significant.

Numerical study on the seismic response of GFRP and steel reinforced masonry shear walls with boundary elements

Reinforced masonry (RM) shear walls with boundary elements (BE) have been recently presented as a ductile alternative to RM rectangular shear walls. The present study addresses the applicability of reinforcing masonry shear walls with glass fibre-reinforced polymer (GFRP) bars to attain reasonable strength and drift. GFRP-RM shear walls are a corrosion-free lateral resisting system that is transparent to magnetic fields and radio frequencies and nonconductive thermally and electrically. A numerical macro-model is developed using OpenSees to simulate the in-plane response of flexure-dominated reinforced masonry shear walls with boundary elements (RMSW-BE). The model was validated against experimentally tested walls from the literature. The boundary elements were designed with C-shaped masonry blocks. A numerical study is performed on thirty-four flexure-dominated shear walls to evaluate the influence of different design parameters on the inelastic behaviour of RMSW-BEs under quasi-static fully reversed cyclic loading. The investigated parameters are transverse hoop spacing, amount of vertical reinforcement in the boundary element, GFRP or steel reinforcement, and aspect ratio of the wall. In addition, walls with rectangular boundary elements were investigated to study the effect of increasing their size on the overall wall response. The influence of the design parameters on the hysteretic response, stiffness degradation, effective stiffness, and ductility related response modification factor was investigated to evaluate the enhancement in the seismic performance of RM buildings with RMSW-BE.

Geometric design and deployment behavior of origami inspired conical structures

This study investigates the folding pattern design and deployment behavior of origami-based foldable conical structures. The geometric analysis is performed to design the six fold line pattern to obtain foldable conical structures. A single-story origami cone, modeled with pin-jointed framework, is selected for the analytical investigation. The axial strains, nodal forces, relative rotation of the fold polygons, and the strain energy during the deployment are obtained analytically. Moreover, the influence of design parameters ( and ) on the deployment behavior of a single story cone is investigated. The results indicate that several fold configurations exhibit a bistable behavior during the motion, and these bistable configurations undergo lesser deformations than other singly stable fold configurations. Then, the folding and deployment process is simulated numerically using FE software to verify the accuracy of the analytical approach. The numerical results are completely consistent with the analytical results. The existence of bistability is verified using the variation of elastic strain energy during the motion. An analytical approach to obtain the bistability points for any conical folding pattern is presented and verified using numerical simulations. The influence of design parameters, materials, and scaling on the bistability point is also investigated. The results show that the bistability is solely a geometrical phenomenon, and scaling does not change the deformation behavior of the cone. Finally, the deployment dynamics of both singly stable and bistable multistory conical structures are discussed, with their potential applications.

Influence of design parameters on the effectiveness of friction isolators in mitigating pre-motion friction in mechanical bearings

Mechanical bearings (i.e., sliding and rolling bearings) are widely used for motion guidance in precision positioning stages due to their low cost, high off-axis stiffness and vacuum compatibility. However, mechanical-bearing-guided stages suffer from the presence of pre-motion (i.e., pre-sliding/pre-rolling) friction which adversely affects their positioning speed and motion precision. Friction isolator has been proposed as a low-cost and robust method for mitigating the undesirable effects of pre-motion friction. It has been experimentally demonstrated that a stage with friction isolator achieves significantly reduced settling times and motion errors in point-to-point positioning and tracking applications, respectively. This paper investigates the influence of design parameters on the effectiveness of friction isolators. Experiments are carried out using three isolators with different parameters to evaluate the settling time and in-position stability during point-to-point motions, and the accuracy and robustness of feedforward friction compensation during circular tracking motions. The experimental investigation is generalized through numerical simulation and frequency domain analysis using a simple model of a friction-isolated stage under the influence of pre-motion friction. Generalized design guidelines are provided based on the observed tradeoffs between different performance metrics (e.g., precision, speed).

Combat helmet liner design for blunt impact absorption using multi-output Gaussian process surrogates

A finite element based computational model simulating the standard drop tower test for military helmets was created and used in conjunction with a multi-output Gaussian process surrogate to seek different designs of helmets for improved blunt impact performance. Experimental drop test results were used for the validation of the model’s ability to simulate impact. The influence of foam stiffness, impact velocity, strap tension, as well as pad placement and size on parameters on the peak linear acceleration (PLA) of the headform was investigated for the first time through a surrogate model trained by strategically choosing simulation points. Impact velocity was found to have the greatest effect. The strap tension and foam pad stiffness ranges examined within this sampling plan were found to have less of an effect on the performance of the helmet than the pad size and shape parameters examined. The surrogate modeling approach was used to quantify the influence of design parameters and can lead to not only improved helmet designs but also new data-driven design metrics and testing standards to accelerate the development of TBI-mitigating helmets.

Numerical investigation and experimental validation of the thermal performance enhancement of a compact finned-tube heat exchanger for efficient latent heat thermal energy storage

This paper presents a numerical study of heat transfer performance inside a compact finned-tube heat exchanger employed in latent heat storage (LHS). A three-dimensional mathematical model of the storage system was developed and validated based on experimental results of charging and discharging. The heat transfer problem during phase change was addressed by solving Navier–Stokes equations combined with enthalpy-porosity technique. Visualization of thermal process inside the storage unit, which cannot be fully realized using an experimental set-up, was carried out by exploiting simulation results. Due to the heat transfer fluid (HTF) circuit design, it was found that phase change occurs faster in the lower half of storage tank and especially in phase change material (PCM) neighboring HTF inlet. Stripes of PCM adjacent to tank walls where heat transport is slow were identified. The model was used to conduct parametric studies of the effects of the HTF inlet temperature, the flow rate, the number and the position of fins on charging and discharging performances. Concerning operation parameters, increasing HTF flow rate from 0.4 to 0.62 l/min reduces charging time by 31% and discharging time by 29%. Similarly, increasing temperature difference between HTF and PCM by 10 °C accelerates melting process by 30% and solidification process by 21%. Since charging is slower than discharging in the studied system, the influence of design parameters on charging was investigated. As a consequence, it was proven that increasing the number of fins reduces melting time and raises storage power. However, adding more than 13 complete fins to the studied device was shown to cause limited improvement. Moreover, positioning fins in the upper half of the heat exchanger has the best benefit on melting time. In addition, increasing fins thickness and changing their material from aluminum to copper was proven to reduce total melting time. Therefore, an improved design was proposed based on the previous conclusions and melting time was reduced by 9% compared to the initial configuration. Comparison of the improved compact finned-tube storage device with other LHS units found in literature showed that the non-dimensional storage time obtained with the novel configuration compares well with other well-established LHS configurations. The results of the present work provide operation and design assistance for LHS systems consisting of compact finned-tube heat exchangers intended to store heat such as solar thermal energy.

Application of High-Voltage Discharges for Disinfecting Water

A three-factor experiment is conducted on the disinfection of water by treatment with high-voltage discharges formed to achieve an electro-hydraulic effect, in order to detect optimal conditions and rules for the course of the processes under study. In the study, a high-voltage installation with an electro-hydraulic spark gap, an EnSURE luminometer (Hygiena) for measuring the level of hygiene of water and its solutions, test tubes for determining the total number of ATP in AquaSnap Total brand water (AQ100X) are used as materials and equipment. The influence of design parameters and exposure modes of an electro-hydraulic installation on the properties of water as a result of the generation of high-voltage discharges is investigated; experimental data are revealed for measuring the level of microbiological contamination of the water sample, which, according to the analysis of the data obtained, is reduced, which can serve as the basis for the possibility of the potential use of the effects of high-voltage discharges as a method of preparing water under irrigation in greenhouses; optimal ratios of factors for disinfecting a pond water sample from a source of artificial origin are revealed: operating voltage 19.9 kV, capacitance 0.1445 μF and the number of discharges 2861 pieces.

Sensitivity analysis of proposed natural ventilation IEQ designs for archetypal open-plan office layouts in a temperate climate

ABSTRACT Designing naturally ventilated deep, open-plan offices could improve occupants’ thermal comfort and productivity and ensure energy reductions; however, this can be challenging when relying on façade only openings. This research examines the ventilation performance sensitivity of atria, innovative façade openings and interior layouts of open-plan offices, in order to identify optimal typologies. Different building typologies are developed through a combination of various atria designs and configurations, with the effective use of high-aspect-ratio (HAR) openings with a similar dimension to that of the floor-to-ceiling height, in either a mid-level vertical (MLV) or high-level horizontal (HLH) orientation. Steady-state computational fluid dynamics (CFD) simulations are performed to predict internal airflow and temperature distribution in a moderate climate and water-bath modelling (WBM) experiments to validate the computational models. Results showed that MLV provide superior cooling potential (up to 2.5°C reductions) and higher ventilations rates; despite, increasing thermal gradients. Unobstructed atria with a horizontal profile similar to that of the building footprint also performed well. Overall, façade opening design was shown to be the most influential design parameter. This research has presented guidance based on reliable results to better equip building designers and architects in the design of successful naturally ventilated deep, open-plan offices.

Design optimization of micromixer with circular mixing chambers (M-CMC) using Taguchi-based grey relational analysis

Abstract The aim of the present study is to optimize the micromixer with circular mixing chambers (M-CMC) using Taguchi-based grey relational analysis approach. Simulations are performed to investigate the effect of design parameters viz. chamber diameter, transverse offset and width of constriction channel on performance characteristics for parameter sets corresponding to Orthogonal Array (OA) L9. Further, grey relational grade is used to identify the optimal set of design parameters. In depth study of flow and mixing dynamics are carried out to visualize the mixing mechanism for optimal and other two cases of proposed micromixer design configuration for Re in the range from 0.1 to 50. In order to assess the response of each design variable at each level, analysis of variance (ANOVA) is also performed to analyse influence of design parameters on mixing index and pressure drop.

Simulation of Magnetic Electron Cut-off in a Vacuum Switch with an Anode in the Form of an Inductor

The simulation of the process of magnetic cut-off of electrons in a vacuum switch (VC) with an anode in the form of an inductor was performed. Calculations were performed according to the physico-topological model of physical processes in the vacuum switch, which took into account current distribution along electrodes, the trajectory of electrons emitted by the cathode and the conditions of current interruption in VC. Determination of current distribution along the anode, as well as configurations of electric and magnetic fields were performed according to a mathematical model based on Maxwell's equations for vacuum and conductive medium of the anode and boundary conditions adapted to the shape of the elements of the VC. Material equations were also used for certainty. The initial kinetic energy of electrons emitted from the cathode was set equal to zero. Their direction of departure from the cathode surface was determined by the direction of the lines of force of the electric field near the surface. Electron emission was given by the uniform distribution of emission points on the surface of the cathode tip. The calculation of the structure of the magnetic field was performed taking into account the secondary magnetic fields and the current distribution over the cross section of the anode inductor, which is caused by the skin effect.It is established that a decrease in the step of the inductor turns and an increase in the amplitude of the current pulse in it lead to an increase in the magnetic field strength in the cathode region, which improves the focusing of electrons. At anode-cathode voltage of 10 kV, the step of the inductor of 6 mm and the amplitude of the anode inductor current pulse of 900 A, all the electrons emitted from the cathode are focused outside the anode.The influence of design parameters on the electron cut-off efficiency is determined. For the investigated design, the optimal cathode-anode distance was 12 mm with a step between the turns of the inductor of 6 mm. The results of calculations showed that reducing the distance between the turns of the inductor increases the efficiency of electron cut-off, which confirms the physical adequacy of the mathematical model and the correctness of the calculations. Calculations also showed that at a cathode-anode distance below 12 mm, the focusing of electrons deteriorates.In the proposed design of the VC with the anode inductor in the form of three turns, the complete cut-off of electrons, i.e. the time of flight of electrons through the electrode system, at anode-cathode voltage of 10 kV, occurred by less than 1 ns at an inductor current pulse of 900 A. The inductor current pulse duration was 5 μs had the form of the half-sinusoid arc. The used method of modeling allows to establish in what part of the inductor pulse the full cut-off of electrons is provided.The obtained results can be used in the development of the VC with interruption of the current of vacuum-arc discharge.

Evaluation of Interactions Between Thermal Piles Integrated in Building Foundations

Abstract This paper investigates the impact of thermal interactions between heat exchangers integrated within building foundation piles to meet space heating and cooling needs of buildings. Specifically, a three-dimensional transient numerical model is developed to evaluate the thermal performance of the foundation piles. The model is used to estimate the temperature variations within the soil medium under various operation conditions of thermo-active foundation (TAF) systems. Then, a series of parametric analyses is carried out to evaluate the influence of design parameters of the piles on the performance of TAF systems, including the interactive effects between piles as well as the impact of these piles on the building slab heat transfer. Then, the parametric analysis results are utilized to develop simplified calculation methods to assess the thermal impacts of the geometric features for the piles on both the performance of TAF systems as well as the building slab heat losses and/or gains. The developed simplified calculation methods are suitable to develop design guidelines in order to enhance the performance of thermal piles to heat and cool buildings.

Influence of design parameters on the field current of the tooth harmonic excitation system

Influence of design parameters on the field current of the tooth harmonic excitation system

On the use of neural networks to evaluate performances of shell models for composites

This paper presents a novel methodology to assess the accuracy of shell finite elements via neural networks. The proposed framework exploits the synergies among three well-established methods, namely, the Carrera Unified Formulation (CUF), the Finite Element Method (FE), and neural networks (NN). CUF generates the governing equations for any-order shell theories based on polynomial expansions over the thickness. FE provides numerical results feeding the NN for training. Multilayer NN have the generalized displacement variables, and the thickness ratio as inputs, and the target is the maximum transverse displacement. This work investigates the minimum requirements for the NN concerning the number of neurons and hidden layers, and the size of the training set. The results look promising as the NN requires a fraction of FE analyses for training, can evaluate the accuracy of any-order model, and can incorporate physical features, e.g., the thickness ratio, that drive the complexity of the mathematical model. In other words, NN can trigger fast informed decision-making on the structural model to use and the influence of design parameters without the need of modifying, rebuild, or rerun an FE model.