Variation Of Design Parameters Research Articles

A Robust Bayesian Optimization Framework for Microwave Circuit Design under Uncertainty

In modern electronics, there are many inevitable uncertainties and variations of design parameters that have a profound effect on the performance of a device. These are, among others, induced by manufacturing tolerances, assembling inaccuracies, material diversities, machining errors, etc. This prompts wide interests in enhanced optimization algorithms that take the effect of these uncertainty sources into account and that are able to find robust designs, i.e., designs that are insensitive to the uncertainties early in the design cycle. In this work, a novel machine learning-based optimization framework that accounts for uncertainty of the design parameters is presented. This is achieved by using a modified version of the expected improvement criterion. Moreover, a data-efficient Bayesian Optimization framework is leveraged to limit the number of simulations required to find a robust design solution. Two suitable application examples validate that the robustness is significantly improved compared to standard design methods.

Experimental investigation of concrete-filled double-skin stainless steel tubular beam-columns

This paper presents an experimental investigation of the hysteretic behavior of concrete-filled double-skin stainless steel tubular (CFDSST) beam-columns with circular hollow section (CHS) outer and inner. A total of 18 specimens were designed and tested under constant axial compressive load and cyclically increasing flexural load to investigate the structural performance of the composite beam-columns and evaluate the effects of varied design parameters, including the thicknesses of the CHS outer and inner and concrete strength, on the performance of the hysteretic behavior of the CFDSST beam-columns. Both of the lateral load (P) versus lateral displacement (Δ) hysteresis response and moment (M) versus drift angel (θ) hysteresis response were obtained. Based on which, the failure mechanism, ductility, energy dissipation capacity, stiffness degradation, and ultimate strength of the specimens were investigated. The results show that the specimens failed in a ductile mechanism features bulge and rupture at the bottom of the CHS outer, unimpaired CHS inner, and local concrete crush, demonstrating the combined effect of the stainless tubes with the concrete. All of the specimens showed high level of ductility and energy dissipation capacity. Finally, comparisons of ultimate bending moments of the beam-columns between the test results and predictions from the existing design codes and design method demonstrate the deign codes underestimates bending moment strength of the CFDSST beam-columns.

Estimation of requirements to signal parameters at V-shaped frequency distribution in mathematical model of multi-position transmitter system

This paper is a brief review of methods for electromagnetic radiation focusing using a multi-position system of radiators based on mutually consistent spatial-amplitude-phase-frequency control of radiated signals and limitations of their potentialities arising from various random fluctuations of signals and antenna parameters. The statistical study of influence of different random and deterministic variations of electrical and design parameters of the antennas, control systems of the radiated signals with V-shaped frequency distribution over the aperture of a multi-position radiating system on the peak power level, duration and repetition period of the focused pulses is carried out. The parameters of the space-amplitude-phase-frequency control law must be stable for a time equal to the average duration of the pulses at the output of the emitters when forming a single space-time pulse, and when forming a sequence of space-time pulses during this pack of space-time pulses. The requirements concerning accuracy and stability of parameters of the signals’ space-phase-frequency control law are considered. The analysis of the influence of various kinds of deviations from the given values of the parameters of the space-phase-frequency control law of emitted signals in the channels of a multi-position system of emitters during formation of space-time pulses sequences is carried out. It is shown that the influence of errors in the location of the phase centers of the emitters in the direction of radiation does not depend on the distance to the focusing point, but is significant and special measures are required to reduce them.

Design and simulation of a gas sensitive junctionless FinFET based on conducting polymer as the gate material

In this study, we demonstrate a multi-gas sensing device utilizing junctionless Fin-shaped Field Effect Transistor (FinFET) with conducting polymer as the gate material. The higher gas response is explained based on workfunction modulation of the conducting polymer gate, Poly(p-phenylene), upon gas molecule absorption. By definition, threshold voltage and off-state current variation before and after gas absorption are considered as two different measures for assessing the responsivity and sensitivity of the sensor. Basically, the main focus of this paper is designing a low power device, in which the change in the electrical characteristics of the device under gas exposure can be detected even in the absence of the gate bias. The high sensitivity of the proposed FinFET device as a gas sensor is mainly attributed to the large surface area of the 3D structure. We optimize the gas-sensing properties by investigating impact of critical physical and structural design parameters on the responsivity and selectivity of the sensor. In addition, statistical analysis is carried out to calculate coefficient of variation (CV) measure, for assessing the change in the responsivity of the gas sensor based on variation of main design parameters. Our results provide a route to design a low power CMOS compatible gas sensor that has fast response with high distinguishing selectivity and can be scaled down to nanoscale regime.

Analysis of Continuous Bioadsorptive Removal of Cadmium in the Light of Circular Economy and Sustainability

The presented study is an experimentation on bioadsorption of cadmium on lentil husk (LH) stacked in fixed bed column reactor. Here the concept of circular economy is integrated to demonstrate its compliance with biological adsorption. In addition sustainability evaluation of the work has been done with respect to environmental, economical and executional procedure. As regard to experimentation adsorption capacity, percentage adsorption and breakthrough time all found to be dependent on the variation of design parameters. Sorbate (cadmium) concentration in treated effluents was inversely proportional to bed height and directly related to flow rate owing to prolonged interaction with metal binding sites. Adsorption capacity (164.25 mg g−1) peaked up at highest feed concentration due to formation of concentration gradient, overcoming the resistance offered during transfer of solute. Desorption was fruitful (up to ~96%) and the fixed bed regained its performing capacity successively. Industrial effluents were reclaimed with high accuracy for considerable duration.

Simulating rooftop solar arrays with varying design parameters to study effect of mutual shading

Rooftop solar arrays are a way of harvesting the energy from sun rays falling on the roof of buildings. These arrays can help buildings to generate power for themselves, either completely or partially fulfilling their energy needs. These systems however have their own sets of factors that can cause losses in them and reduce their power output. In this research work, the effect of mutual shading and design parameters are studied. The rooftop solar arrays with different parameters are simulated that help to estimate results closely agreeable with practical outcomes. The software ‘DIVA for Rhino’ was used to perform the simulations. The effect of various parameters such as the inclination of the roof surface, inter-row spacing of the panels, and their inclination, were studied. The degree of mutual shading was observed by varying these parameters. The power outputs and payback periods of the simulated systems were compared and their trends were observed to give a better understanding of how these factors affect rooftop solar arrays. The shading loss was high for higher panel inclination values coupled with smaller inter-row spacing. A higher roof inclination reduced the level of shading loss as it reduced the panel inclination with respect to the roof surface. The roof surface area increases with its inclination, which means more space for solar panels and hence a higher array power output. The results of the simulations will help in better decision-making during the construction of rooftop solar arrays as it helps to see the extent to which each of these parameters affects them.

Sensitivity Analysis Based NVH Optimization in Permanent Magnet Synchronous Machines Using Lumped Unit Force Response

Acoustic noise and vibration sources in electric machines are mainly of electromagnetic and structural origin. A lumped structural unit response-based sensitivity analysis procedure is proposed in this article, which isolates electromagnetic and structural impacts brought by variation of different design parameters in a fractional slot concentrated winding, surface mounted permanent magnet synchronous machine (SPMSM). The impact of ten design parameters on average torque, torque ripple, synchronous inductance, dominant spatial-temporal order airgap force, cogging torque, friction torque, dominant mode frequency and structural unit response is studied in detail for a 12 slot/10 pole (12s10p) SPMSM. Analysis reveals that on a 12s10p SPMSM, slot opening has a very high impact on dominant airgap force component. A multilevel nonlinear regression model-based fast optimization strategy is introduced considering electromagnetic and structural design objectives and constraints following the sensitivity analysis. The optimized design is prototyped to validate the proposed design approach. Impact hammer-based modal analysis, no load, load and run-up tests are performed on the prototype for experimental validation. Ranging from structural tests to electromagnetic tests, the experimental results closely follow and validate the simulation-based predictions.

Prediction of Elastic-Softening-Debonding behavior for CFRP Tendon-Adhesively bonded anchors

The anchor for carbon fiber reinforced polymer (CFRP) tendon is a key component applied in prestressed structures using CFRP cables. The damage due to cracking and debonding in the anchor zone influences the anchor system performance significantly. On the basis of interface mechanics theory, a trilinear bond-slip law was applied to derive the theoretical models of the stress distribution, tendon slip, and ultimate bearing capacity of the adhesively bonded anchor in various loading stages. The initiation of the local debonding as well as the softening and debonding propagation were modeled. The theoretical models were assessed with respect to experimental results. The influence of variable design parameters on the anchor performance was investigated. The results show that the proposed theoretical models are valid. The interface of the adhesively bonded anchor may undergo a series of stages; from the elastic stage to the softening stage and finally to the debonding stage when subjected to an axial tensile loading. Various closed-form solutions can be derived for different stages that leads to a discovery of an effective bond length. When the bond length is within this effective length, the tensile load capacity increases with respect to the anchor length. Otherwise, the ultimate capacity can hardly be improved by increasing the bond length. The increase in axial rigidity of the bonding medium improves the effective bond length and the ultimate load capacity of the anchor. Moreover, this growth rate is influenced by the diameter of the tendon.

Efficiency of a randomized confirmatory basket trial design constrained to control the family wise error rate by indication.

Basket trials pool histologic indications sharing molecular pathophysiology, improving development efficiency. Currently, basket trials have been confirmatory only for exceptional therapies. Our previous randomized basket design may be generally suitable in the resource-intensive confirmatory phase, maintains high power even with modest effect sizes, and provides nearly k-fold increased efficiency for k indications, but controls false positives for the pooled result only. Since family wise error rate by indications may sometimes be required, we now simulate a variant of this basket design controlling family wise error rate at 0.025k, the total family wise error rate of k separate randomized trials. We simulated this modified design under numerous scenarios varying design parameters. Only designs controlling family wise error rate and minimizing estimation bias were allowable. Optimal performance results when . We report efficiency (expected # true positives/expected sample size) relative to k parallel studies, at 90% power ("uncorrected") or at the power achieved in the basket trial ("corrected," because conventional designs could also increase efficiency by sacrificing power). Efficiency and power (percentage active indications identified) improve with a higher percentage of initial indications active. Up to 92% uncorrected and 38% corrected efficiency improvement is possible. Even under family wise error rate control, randomized confirmatory basket trials substantially improve development efficiency. Initial indication selection is critical.

Sensitivity analysis and optimization of design parameters of heating tower heat pump

Heating tower heat pumps (HTHPs) are evolving rapidly owing to their high performance and adaptability. However, the lack of relevant design standards causes mismatches between components and leads to low operation efficiency. To address this problem, this study proposes a framework to optimize the design parameters of HTHPs. Case studies in 21 locations in different climate regions are carried out to investigate the saving in energy and costs. The results suggest that an increase in the design airflow flux (Ga), solution flow flux (Gs), water flow flux (Gw), or heat exchange area of the tower (A) can improve the performance of the heat pump unit and reduce the regeneration load. However, they can increase the energy consumption of the fan and pump, or the initial cost of the components. Considering 10-year lifecycle costs as the criterion, the optimal combination of Ga, Gs, Gw, and A is determined from 15,625 matrices with varying design parameters for each location. For the locations whose mean relative humidity (MRH) is approximately 70% during winter operations (e.g., Nanjing and Shanghai), the optimal design approach and range in winter are approximately 2.6 and 2.9 °C, respectively; these change to 4.7 and 6.6 °C in summer conditions. The Gs and Gw are 3.26 and 3.24 kg m−2 s−1, respectively, and Ga is 1.08 kg m−2 s−1 in summer and 2.94 kg m−2 s−1 in winter. The areas with MRH around 80% (e.g., Chongqing and Changsha) should have larger Ga and A, and lower Gs in winter, which can significantly reduce the energy used in regeneration. The regions with MRH less than 65% (e.g., Tianjin and Beijing) should have smaller Ga and A, and higher Gs in winter, which can reduce the negative effects of evaporative cooling. Compared with the conventional design parameter matrices, the optimal ones can save 7.01%, 9.91%, and 3.81% lifecycle costs, respectively, in the above three types of climate regions.

Machining of Zircaloy-2 using progressive tool design in EDM

ABSTRACT Zircaloy-2 is used in nuclear and biomedical industries therefore required high accuracy and precision, and achieved by application of electrical discharge machine (EDM). In this study, a new horizon of tool design is investigated for improvement in the performance of EDM. To measure the effect of tool design, Zircaloy-2 is machined with EDM using progressive Cu tool and measured the response parameters (MRR, TWR, radial overcut (Roc ), radial undercut (Ruc ), taper angle (Φ), and surface roughness). The progressive tool with varying design parameters of rake angle (0°, 45°, and 60°), flat land (2 mm), trunk diameters (10, 8, and 6 mm), and relief angle (0°, 45°, and 60°) are used to perform rough and finish machining in single EDM operation. MRR and SR are increased with increase in rake angle due to reduction in oxide and carbide deposition on the machined surface. Best combination for maximum MRR (1.131 × 10−3 mm3/min), minimum SR (4.313 µm), and minimum taper angle (2.17°) is obtained when machining is performed using T7. Multiresponse optimization (R-method) gives highest rank to progressive tool T7. Tool design improved TWR and significant reduction in radial overcut over conventional tool.

Influence of wind turbine design parameters on linearized physics-based models in OpenFAST

Abstract. While most physics involved in wind energy are nonlinear, linearization of the underlying nonlinear wind system equations is often important for understanding the system response and exploiting well-established methods and tools for analyzing linear systems. Linearized models are important for eigenanalysis (to derive structural natural frequencies, damping ratios, and mode shapes), controls design (based on linear state-space models), etc. In controls co-design, wherein methods often rely on linearized time-domain models of the physics, the physical structure (often called the plant) and controller are designed and optimized concurrently, so it is important to understand how changes to the physical design affect the linearized system. This work summarizes efforts done to understand the impact of design parameter variations in the physical system (e.g., mass, stiffness, geometry, and aerodynamic and hydrodynamic coefficients) on the linearized system using OpenFAST.

Psychoacoustic modelling of rotor noise.

The aviation sector is rapidly evolving with more electric propulsion systems and a variety of new technologies of vertical take-off and landing manned and unmanned aerial vehicles. Community noise impact is one of the main barriers for the wider adoption of these new vehicles. Within the framework of a perception-driven engineering approach, this paper investigates the relationship between sound quality and first order physical parameters in rotor systems to aid design. Three case studies are considered: (i) contra-rotating versus single rotor systems, (ii) varying blade diameter and thrust in both contra-rotating and single rotor systems, and (iii) varying rotor-rotor axial spacing in contra-rotating systems. The outcomes of a listening experiment, where participants assessed a series of sound stimuli with varying design parameters, allow a better understanding of the annoyance induced by rotor noise. Further to this, a psychoacoustic annoyance model optimised for rotor noise has been formulated. The model includes a novel psychoacoustic function to account for the perceptual effect of impulsiveness. The significance of the proposed model lies in the quantification of the effects of psychoacoustic factors, such as loudness as the dominant factor, and also tonality, high frequency content, temporal fluctuations, and impulsiveness on rotor noise annoyance.

Numerical Simulation of the Stress-Strain State of a Hybrid Titanium-Polymer Composite Material for Optimizing the Design of Aircraft Structures

Work on the current topic of hybrid titanium-polymer composite materials (TPCM) is continuing. After checking the technological feasibility of two-stage processes for manufacturing parts of flat shapes and with a single curvature, identifying opportunities for improving the adhesive interaction, work is carried out to assess the possibility of varying design parameters, such as reinforcement schemes, combinations of components, etc.in order to obtain optimal properties of manufactured parts.

Modeling of Soft Pneumatic Actuators with Different Orientation Angles Using Echo State Networks for Irregular Time Series Data.

Modeling of soft robotics systems proves to be an extremely difficult task, due to the large deformation of the soft materials used to make such robots. Reliable and accurate models are necessary for the control task of these soft robots. In this paper, a data-driven approach using machine learning is presented to model the kinematics of Soft Pneumatic Actuators (SPAs). An Echo State Network (ESN) architecture is used to predict the SPA’s tip position in 3 axes. Initially, data from actual 3D printed SPAs is obtained to build a training dataset for the network. Irregular-intervals pressure inputs are used to drive the SPA in different actuation sequences. The network is then iteratively trained and optimized. The demonstrated method is shown to successfully model the complex non-linear behavior of the SPA, using only the control input without any feedback sensory data as additional input to the network. In addition, the ability of the network to estimate the kinematics of SPAs with different orientation angles is achieved. The ESN is compared to a Long Short-Term Memory (LSTM) network that is trained on the interpolated experimental data. Both networks are then tested on Finite Element Analysis (FEA) data for other angle SPAs not included in the training data. This methodology could offer a general approach to modeling SPAs with varying design parameters.

Analytical model of subthreshold drain current for nanoscale negative capacitance junctionless FinFET

In this article, an analytical Subthreshold Drain Current model has been developed for Negative Capacitance Junctionless FinFET (NC-JL FinFET). To obtain the subthreshold current model for NC-JL FinFET the drift-diffusion equation is solved by including negative capacitance effect through LK equation and further utilized to attain the expression of subthreshold slope (SS). The influence of the fringing field due to source/drain spacer on the subthreshold current has been included in the model. The model predictions turn out to be in fair agreement with numerical simulation results. The performance of NC-JL FinFET is also examined for different technology nodes. Also, the influence of physical parameters like ferroelectric thickness, gate dielectric constant, fin thickness, spacer length etc. has also been analyzed. Further, the SS is also examined for variations in several device design parameters. It has been revealed that the NC-JL FinFET improves subthreshold current and SS by almost 80% and 16.7%, respectively as compared to JL FinFET.

Fracture characteristics of asymmetric high contact ratio spur gear based on strain energy release rate

Variations in design parameters and methodology have a significant effect on the fracture characteristics of spur gear. Furthermore, the geometry and load acting on the spur gear affect the propagation of fractures and the bending fatigue life. In comparison with conventional gear design, the direct design strategy is a highly efficient method for improving fracture resistance. This study attempts to investigate the fracture properties of a direct designed asymmetric high contact ratio (AHCR-DD) spur gear subjected to the mix-mode of crack failures. The stress intensity factor (SIF) and the shape factor are compared to conventional normal and high contact ratio spur gears. In addition, the fracture properties of conventional design symmetric HCR (SHCR-CD), direct design symmetric HCR (SHCR-DD), and AHCR-DD spur gears are compared. When compared to other gears, the AHCR-DD spur gear has a higher fracture resistance. A parametric study of the fracture properties of the AHCR-DD spur gear is also carried out to provide useful information for designing such gears. Variations in the contact ratio, rim thickness, number of teeth, and addendum pressure angle are used to assess fracture performance. It is observed that using a direct design technique significantly reduces the SIF. This investigative study provides valuable guidelines in the future for developing non-standard spur gears such as AHCR-DD.

Single‐Material, Near‐Infrared Selective Absorber Based on Refractive Index‐Tunable Tamm Plasmon Structure

AbstractAs a powerful planar plasmonics, Tamm plasmon (TP) structures open up new possibilities for high‐efficiency photonic applications demanding high quality (Q)‐factor with scalability and spectral tunability. Despite the theoretical advantages of TP structures, TP configurations alternately stacked within limited materials and integer ranges result in thicker device sizes and still struggle to achieve ideal designs. Here, by introducing a computational model with varying design parameters, the configurations of high‐performance TPs are presented within thin scale. However, the optimized configuration is hard to be realized with limited conventional materials. In this study, the effective refractive index is tailored through porosity change to achieve optimized design parameters, resulting in high Q‐factors (≈45) and near‐unity absorptance (≈99%) for sub‐micron scale TPs (≈0.7 µm) based on single material. To verify single‐material TPs (SMTPs), the real and imaginary parts of the optical impedances are calculated, which are well matching each other, resulting in unity absorption. Using the designed structure, SMTPs are experimentally fabricated based on glancing angle deposition. As a practical demonstration, SMTPs are combined with a metal–semiconductor–metal photodetector as an ultra‐sensitive narrowband photodetector.

Comparative study of Inplane gradient cellular pattern honeycombs with Uniform compliant honeycombs

Cellular structures have gained attention in recent years due to its wide range of applications across various fields. One of its categories are the “Honeycombs”, honeycomb structures that came into existence at the end of 1930’s. The shapes of these structures are taken from nature, that is, the shape of a beehive. Honeycomb structures have a huge potential in terms of mechanical properties, enhancing the performance of structures and many other traits which have gained the attention of researchers switching from the conventional materials. This paper compares the energy absorption and stability properties of gradient honeycomb structures (with varying cell size across the width) with conventional or compliant structures (uniform cell size throughout the structure). Analysis is done on structures with “In-plane orientation” by varying design parameters. Using numerical modelling and FEA analysis in ANSYS software, the results are validated.

Effect of design strength parameters of conventional two-way singly reinforced concrete slab under concentric impact loading

Damage evaluation and performance enhancement of the structures due to ever-rising malicious sporadic explosions, accidental detonations, vehicular collisions, aircraft crashing, falling construction equipment, and rock/boulder impact from landslips are of considerable concern and thus generate sufficient interest to structural engineers and researchers. In general, the mode of damage to a structure and its degree depends upon which element(s) of the structure is subjected to such impulsive loadings, damage resistance, and energy transferred to the element(s). For a deeper understanding of the failure mode and impact resistance, analysis of the structural elements under impulsive loadings (blast and impact) with varying design parameters seems necessary. The present work undertakes a numerical study to investigate the dynamic behavior of 1000 mm × 1000 mm × 75 mm two-way square singly reinforced concrete slab subjected to drop-weight impact loading at its centroid using a finite element method based commercial dynamic computer code, ABAQUS/Explicit version 6.15. The impact load is applied via a hard steel cone frustum-headed drop weight with a flat impacting face of mass 105 kg having a free-fall from a height of 2500 mm with an impacting velocity of 7.0 m/sec. Two well-known material models namely; Concrete Damage Plasticity (CDP) and Johnson-Cook (J-C) for concrete and steel, respectively, with strain rate effects have been considered. The numerical model of the slab is validated with the impact test results/observations in the open literature. Analyses have been extended to investigate the influence on the impact resistance of the slab by varying slab thickness and concrete strength without altering cover to the concrete, quantity and yield strength of the flexural steel reinforcement on the impact resistance of the slab. The slab is not provided with shear reinforcement. Three different concrete strengths (30, 40, and 50 MPa) for four slab thicknesses (75, 100, 125, and 150 mm) are considered for the parametric investigation. Results have been compared and discussed with regards to peak displacement and impact resistance of the slab.