Variation Of Design Parameters Research Articles

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.

Chameleon Swarm Algorithm Assisted Optimization of U-Slot Patch Antenna for Quad-Band Applications

Existing optimization algorithms are insufficient in the face of problems with difficult measurement functions as well as a large number of design parameters. Therefore, to achieve such challenging applications, the Chameleon swarm algorithm and its variants, which belong to the family of meta-heuristic algorithms that have not been used in any antenna optimization study before, are used together with 3 different objective functions fitted from mathematical models. Then, a U-slot antenna application with 12 different variable design parameters with resonance frequencies of 3.5 GHz, 3.7 GHz, 5.2 GHz and 5.8 GHz is considered as a multidimensional and single-objective optimization problem. In this study, first of all, the success of the algorithm is reinforced by comparing the performance with other commonly used single and multi-objective optimization algorithms. In addition, the results obtained with different population parameters, weight coefficients, objective functions and variant models were compared. All these processes are compared within themselves, and the antenna results of the most successful result are displayed as 3D electromagnetic simulation. The results show that the optimization processes proposed for an antenna designer are a safe, practical and efficient solution for multidimensional and single-objective antenna optimization applications. In addition, any optimization problem with a large number of variable design parameters can undoubtedly be adapted to the Chameleon swarm algorithm.

Experimental investigation of performance of high-shear atomizer with discrete radial-jet fuel nozzle: mean and dynamic characteristics

The present study focuses on the performance of a novel high-shear atomizer with a discrete radial-jet fuel nozzle to overcome the constraints associated with the simplex-pressure-swirl and duplex-fuel nozzles at the high-end power demand of a gas turbine combustor. The high-shear atomizer consists of multiple inner and outer radial swirlers with interchangeable flare and fuel nozzle. The performance of the atomizer with discrete radial-jet fuel nozzle is elucidated at ALR (mass ratio of air to liquid) 14.1 through variations in geometrical design parameters of the swirl cup. The parameters of interest are the split ratio (γ), relative swirl direction of inner and outer swirler (co- and counter-rotation), flare angle (θ) and flare mixing length (η). Spray characteristics at ALR 4.72, 7.08 and 9.44 are also presented for an atomizer by freezing the geometrical design. The particle image velocimetry diagnostic technique is employed to capture the spray flow field. The non-dimensional radial (W/Df; W, radial width of CTRZ (in mm) and Df, exit diameter of flare (mm)) and axial (L/Df) sizes of the central toroidal recirculation zone and near field swirl number (SN5) of the flow are explored. Further, variations in the droplet size distribution of the atomizer across all the ALR are discussed in detail. The Sauter mean diameter across all the test cases is found to be in the range of 9–30 μm, 15–37 μm, 15–50 μm and 23–75 μm at ALR 14.1, 9.44, 7.08 and 4.72 respectively, which shows good atomization capability of the atomizer with discrete jets. The spatial distribution of the spray volume/mass in an azimuthal plane is examined in the circumferential and radial directions, which shows consistent and excellent azimuthal symmetry of the spray even with a decrease in ALR value. The overall mean and dynamic spray characteristics of the atomizer suggest that high-shear atomizer in combination with a discrete radial-jet fuel nozzle would be a better candidate than an atomizer with a simplex pressure-swirl fuel nozzle in rich-quench-lean concept-based gas turbine combustors.

A simulation-based analysis of the effects of variable prosthesis stiffness on interface dynamics between the prosthetic socket and residual limb.

Introduction: Loading of a residual limb within a prosthetic socket can cause tissue damage such as ulceration. Computational simulations may be useful tools for estimating tissue loading within the socket, and thus provide insights into how prosthesis designs affect residual limb-socket interface dynamics. The purpose of this study was to model and simulate residual limb-socket interface dynamics and evaluate the effects of varied prosthesis stiffness on interface dynamics during gait.Methods: A spatial contact model of a residual limb-socket interface was developed and integrated into a gait model with a below-knee amputation. Gait trials were simulated for four subjects walking with low, medium, and high prosthesis stiffness settings. The effects of prosthesis stiffness on interface kinematics, normal pressure, and shear stresses were evaluated.Results: Model-predicted values were similar to those reported previously in sensor-based experiments; increased stiffness resulted in greater average normal pressure and shear stress (p < 0.05).Conclusions: These methods may be useful to aid experimental studies by providing insights into the effects of varied prosthesis design parameters or gait conditions on residual limb-socket interface dynamics. The current results suggest that these effects may be subject-specific.

Multi-Body Simulation of a Novel Electrode Stacking Process for Lithium-Ion Battery Production

Stack assembly in lithium-ion battery production is limited regarding productivity. This paper presents a novel electrode stacking process with a rotational handling device enabling a continuous and therefore high-throughput material flow. The design parameters of the handling device and the peripherals influence the stacking process, but their correlations are unknown so far. To examine the dynamics and forces acting on the electrode, a multi-body simulation of the process was conducted with variable design and process parameters. The results show significant interactions between these parameters, especially between rotational velocity of the handling unit, feeding position, and feeding rate of the electrodes.

Verification and improvement of flexible mathematical procedures for co-optimizing design and control of fuel cell hybrid vehicles

A study on the usefulness of flexible mathematical tools for determining the optimal architecture of fuel cell hybrid vehicles is presented. Starting from a pre-existing powertrain and control strategies co-optimization tool, the technological (especially in terms of lithium battery type) search domain was first expanded by including an updated battery model. Afterward, the availability of specification independent control strategies was exploited in such a way as to enable two optimization tasks: one relying on previous heuristic control rules and the other based on newly optimized control strategies. The results evidenced negligible differences, in terms of key control variable trends, objective (i.e., fuel economy), and design parameters (i.e., fuel cell system size and battery energy density), thus further proving the tool versatility. Moreover, optimal configurations exhibit appreciable fuel economies and acceleration performance on the WLTP driving cycle, while proposing potentially cost-effective solutions in terms of fuel cell system size.

Additive manufacturing enabled designs for dental applications: A conceptual study

Additive manufacturing (AM), or commonly also known as three-dimensional (3D) printing, has fundamentally changed the way products are designed and manufactured due to its freeform fabrication capabilities. As AM becomes more mainstream and accessible, it is therefore important to adopt new designs, or re-designing approaches, for existing products that would allow parts to be manufactured by these techniques. This study conceptualizes and derives new suitable designs for dental abutment connector used in dental implants and proof of concept is achieved using laser-based powder bed fusion of metals (PBF-L/M). The functionality of the design is tested using simulations by running static and cyclic loading to ensure that the new design can withstand a normal human bite force. Design optimization is also conducted by varying design parameters to achieve minimal Von Mises stresses throughout the abutment. Finally, the designs are compared using various design considerations and it is concluded that snap fit design is the most suitable for dental abutment due to ease of use and manufacturability.

SENSITIVITY OF STRENGTH, RIGID AND DYNAMIC CHARACTERISTICS OF THE CONSOLE ROTOR TO VARIATION OF DESIGN PARAMETERS

The analysis sensitivity of strength, rigid and dynamic characteristics of the console rotor to variation of design parameters in paper describes The speed of rotation of the shaft, the material of the impeller vary. The dependences of radial and axial displacements on the angular velocities of rotation and the modulus of elasticity of the impeller material are established. For objects of the type of rotary systems with a cantilever arrangement of the impeller, not one, but a set of criteria has been introduced into consideration, which should be taken into account in the research of this type of objects. The tendencies of change of the first and second critical rotational speeds from the modulus of elasticity, rotor rotational frequencies and density of the impeller material are also determined. On this basis, recommendations have been developed for determining the design parameters of the rotor part of the air blower with a cantilevered impeller. Keywords: air blower; critical rotation speed; natural vibration frequency; rotary system; stress-strain state

China Sponge City database development and urban runoff source control facility configuration comparison between China and the US

Urban runoff source control facilities (URSCFs) are important parts of Sponge City (SC) by controlling urban flooding, restoring eco-balance, and enhancing city resilience. To evaluate the performance of URSCF, one needs to summarize and analyze the past SC construction and operation data. Previous studies however are predominately engineering practice studies. There lacks localized reference datasets to quantitatively evaluate the performance and guide public policy development for SC. Therefore, it is imperative to develop a database, which would summarize data obtained through the already completed pilot sponge cities, and provide a reference for future URSCFs planning and construction. This study makes a zero to one breakthrough by establishing a SC database using New Orleans method. Then statistical results of facility type, size, and costs information for 30 pilot sponge cities have been summarized and analyzed. The URSCFs type distribution statistical results show that bioretention, permeable pavement, detention cell, grassed swale and constructed wetland are the top five most constructed facilities in China. The cost statistical results display that the range of facility cost collected is usually larger than the range given by the reference value, which may attribute to the variation in material cost, labor cost and design parameters in different cities. To check the similarities and differences of URSCFs parameters between China and the US. A configuration parameters comparison of URSCFs has been conducted. Bioretention is taken as an exampl. Comparison results show that factors such as climate type, geographical environment, and socio-economic conditions will affect the configuration parameters of URSCFs. The groundwater depth and designed rainfall intensity are mainly influenced by local climate and geographical conditions. Surface area is influenced by local socio-economic conditions. The thickness of the covering layer and drainage layer are not affected by geographic location. The service area ratio, water storage depth and planting soil layer thickness are significantly different between China and the US.