Dimensional Calculations Research Articles

Soft Sensor for Real-Time Monitoring of Automotive PEM Fuel Cell Systems

System strategies to enhance the performance and mitigate degradation of automotive polymer electrolyte membrane (PEM) fuel cells require knowledge of the internal states such as the membrane hydration and its temperature [1]. This information is rarely available through direct measurements onboard the vehicle, since measuring such quantities requires advanced hardware sensors that can significantly add to the system costs. Therefore, accurate mathematical models are necessary to provide the critical information about internal states. These models should have a high enough fidelity to describe the salient physical phenomena with an acceptable degree of accuracy, while maintaining a high level of computational efficiency so that the required computations can be carried out online. Despite significant efforts in the PEM fuel cell modeling community, balancing the computational cost and model fidelity requirements remains a challenge. Most of the models proposed to date obtain high fidelity by solving detailed transport equations on a fine spatial grid. These models have been instrumental in clarifying the role of complex and coupled transport phenomena in an operating fuel cell [2], [3]. Nevertheless, they typically require significant computational resources and are not suitable for online applications. On the other hand, available computationally-efficient models often disregard multiple important physical phenomena to achieve high performance [4], [5]. To fill this gap, we have developed a model that takes most of the important physical phenomena into account and achieves computational efficiency by spatio-temporal decoupling of the problem [6], [7]. In this talk, we will present our recent efforts on further improving the model by incorporating mass transport losses in the cathode catalyst layer and designing a new iterative scheme that enables simulation of counter-flow configuration. Moreover, we present our most recent results on model parameterization and validation with different performance datasets. The results indicate the computational efficiency of the model and its capability to reproduce experimental performance measurements with high accuracy. * B.L. Pence is currently with the department of Mechanical Engineering at the Brigham Young University, Rexburg, ID. Acknowledgement: Financial support for this work was provided by Ford Motor Company. [1] A. Goshtasbi and T. Ersal, “LQ-MPC Design for Degradation-Conscious Control of PEM Fuel Cells,” in Proceedings of the 2019 American Control Conference, 2019. [2] L. Hao, K. Moriyama, W. Gu, and C.-Y. Wang, “Three dimensional computations and experimental comparisons for a large-scale proton exchange membrane fuel cell,” J. Electrochem. Soc., vol. 163, no. 7, pp. F744–F751, 2016. [3] A. Goshtasbi, P. Garcia-Salaberri, J. Chen, K. Talukdar, D. G. Snachez, and T. Ersal, “Through-the-Membrane Transient Phenomena in PEM Fuel Cells: A Modeling Study,” J. Electrochem. Soc., vol. 166, no. 7, 2019. [4] A. Headley, V. Yu, R. Borduin, D. Chen, and W. Li, “Development and experimental validation of a physics-based pem fuel cell model for cathode humidity control design,” IEEE/ASME Trans. Mechatronics, vol. 21, no. 3, pp. 1775–1782, 2016. [5] M. Grötsch and M. Mangold, “A two-phase PEMFC model for process control purposes,” Chem. Eng. Sci., vol. 63, no. 2, pp. 434–447, 2008. [6] A. Goshtasbi, B. L. Pence, and T. Ersal, “A real-time pseudo-2D bi-domain model of PEM fuel cells for automotive applications,” in ASME 2017 Dynamic Systems and Control Conference, 2017, p. V001T25A001-V001T25A001. [7] A. Goshtasbi, B. L. Pence, and T. Ersal, “Computationally efficient pseudo-2D non-isothermal modeling of polymer electrolyte membrane fuel cells with two-phase phenomena,” J. Electrochem. Soc., vol. 163, no. 13, pp. F1412–F1432, 2016.

Thermal Transmittance around Edge of Vacuum Glazing

The main objective of the calculations thermal performance properties of the edge of vacuum glazing was the quantification of the heat flow around edge of glazing. Additional heat flow around edge of glazing is expressed by means linear thermal transmittance. Linear thermal transmittance of the junction between edge vacuum glazing and wooden frame or wooden-aluminium frame was calculated by using a two dimensional (2D) numerical calculations. Edge sealing of vacuum glazing is assumed by means solder glass with Indium metal strip, so it is metal-based edge seal. In vacuum glazing the edge seal acts as a thermal bridge between the glass sheets. Heat? ows from the glass sheet on the warm side through the edge seal to the sheet on the cold side, not only does it increase the overall thermal performance of the glazing, but also it causes temperature variation (decrease surface temperatures) and stress in the edge region.

Structural Reinforcement of a Masonry Building

A structural reinforcement carried out on a 12th century mansion in masonry with the aim of a seismic improvement valued as a decrease in the Seismic Risk Class [4].The reinforcement technique combines the use of FRP systems with carbon fiber strips applied to the external perimeter walls and FRCM systems applied to the internal walls.The proposed solution allows the seismic improvement both in relation to local failure phenomena and in the overall behavior of the whole structure. Particular focus is given to the dimensional calculation of the reinforcements and to the combined contribution of the two techniques, highlighting the peculiarities of both. The FRP system is used to avoid overturning and to increase the resistance of the walls, while the FRCM system is used for the general improvement of the mechanical properties of the masonry. Particular attention is paid to the evaluation of the design resistance values related to the debonding failure by carrying on special technical measures in installation of aramid fiber or CFRP connectors.The intervention methodology allows an increase of the Seismic Risk Class of at least 3 levels, as deductible from the calculation of the PAM value.

THREE-COMPONENT LENS ZOOM-AFOCAL SYSTEMS FOR TRANSFOCATORS

Background. Parametric synthesis of zoom-afocal optical systems for zoom lenses. Development of an algorithm for dimensional calculation of three-component zoom-afocal systems when accounting overall limitations, providing the desired range of changes in the angular magnification and field of view of the zoom lens, the allowable vignetting of the extreme beams of light when the field of view changes over the entire specified range. Synthesis of an afocal system for a stationary lens, the entrance pupil of which is located behind the afocal system.Objective. The purpose of the paper is to create a universal analytical and suitable for computer automation algorithm for calculation of the optical and overall parameters of the components of zoom-local three-component zoom systems.Methods. The zoom-afocal system is represented by subtle components. A system of equations is compiled in which the distances between the components are unknown. From the equations, the values of these distances are recovered, which provide the necessary values of the angular magnification and zero optical power of the afocal system. In this case, the magnitudes of the optical powers of the components and their ratios should ensure positive values of the distances between them. Using the formulae of the angles and heights of the zero rays on the components of the system, taking into account the permissible vignetting of the beam of rays from the edge of the field of view, the required light diameters of the components are determined.Results. The obtained analytical dependences allow us to determine the focal distances of the afocal system components and their mutual location over the entire required range of changes in the angular magnification using the original data on the allowable longitudinal and transverse dimensions of the afocal system. It is shown that afocal systems have a maximum axial length with the angular increase of one. The largest light diameter has the first component. The diameter of this component reaches its greatest value as the value of the angular increase is close to one.Conclusions. The obtained results allow analytically performing parametric synthesis of three-component zoom-afocal systems, taking into account the requirements for their dimensions, the range of changes in the angular magnification and permissible vignetting of beams of rays from the edge of the visual field.

Development of the integrated parallelism strategy for large scale depletion calculation in the Monte Carlo code RMC

The Monte Carlo (MC) method is becoming more and more attractive for high fidelity simulations in reactor physics. The huge memory consumption is the bottleneck in the three dimensional (3D) full core detailed depletion calculations. Three strategies were proposed to overcome the memory problem, including domain decomposition, data decomposition and hybrid parallelism. These methods can solve this problem in some extent, but each of them has its own limitation. In this paper, the integrated parallelism platform which combines these three strategies was proposed and developed in the Reactor Monte Carlo (RMC) code. Based on this platform, the performances of different combinations of these three strategies were investigated on PWR assembly and PWR full-core models on the Tianhe-2 supercomputer. The results show that “domain decomposition + hybrid parallelism” performed better than “tally data decomposition + hybrid parallelism” at the scale of above 0.6 million burnup regions. Moreover, the batch method was adopted to reduce the frequency of collective communications and thus save computational time. Finally, the strategy of “domain decomposition + burnup data decomposition + hybrid parallelism” with the batch method was proposed and tested on Tianhe-2 supercomputer compute nodes, equipped with 64 Gigabytes (GB) of memory. The proposed strategy can handle about twenty millions of burnup regions with high efficiency, which is the important foundation of full core detailed depletion calculation and high fidelity simulation.

ТРАНСПОРТНЫЙ ВАРИАНТ НЕСТАЦИОНАРНОГО ДИФФУЗИОННОГО ТЕСТА BSS-6

For one dimensional benchmark BSS-6 calculation by SUHAMD-TD and SUHAM-TD codes (nonsta-tionary solution in diffusion and surface harmonic method models with using delayed neutrons), by KIR (time dependent Monte Carlo method) and LUCKY-A code (discrete ordinate method for time dependent transport equation solution with using of parallel calculations). Transport cross sections for codes KIR, LUCKY-A and SUHAM-TD were obtained from diffusion coefficients for neutron groups to make kinetic calculation. Right and left boundary conditions for plate were zero for diffusion model and vacuum (not angular fluxes into plate) for kinetic model.

Ultrafast Photoinduced Dynamics of 1,3-Cyclohexadiene Using XMS-CASPT2 Surface Hopping.

A full-dimensional simulation of the photodissociation of 1,3-cyclohexadiene in the manifold of three electronic states was performed via nonadiabatic surface hopping dynamics using extended multistate complete active space second-order perturbation (XMS-CASPT2) electronic structure theory with fully analytic nonadiabatic couplings. With the 47 ± 8% product quantum yield calculated from the 136 trajectories, generally 400 fs-long, and an estimated excited lifetime of 89 ± 9 fs, our calculations provide a detailed description of the nonadiabatic deactivation mechanism, showing the existence of an extended conical intersection seam along the reaction coordinate. The nature of the preferred reaction pathways on the ground state is discussed and extensive comparison to the previously published full dimensional dynamics calculations is provided.

Effect of Gurney Flaps on the Aerodynamic Characteristics of NACA 0010 Cascades

Abstract Two dimensional computations were conducted to investigate the performance of NACA 0010 cascades with Gurney Flaps. The cascades with three different stagger angles (βB) viz. 45°, 90° and 135° were studied for the aerodynamic performance characteristics of the blades with and without Gurney Flaps and the results were compared. The Gurney Flap’s length is 2 % of the chord length and has a 45° inclination with respect to the chord line. A significant lift augmentation is observed in all the three blade angle configurations due to the Gurney Flap. In terms of aerodynamic efficiency, it was observed that the presence of Gurney Flap was detrimental when βB = 45°, while the same was highly advantageous when βB = 135°. The streamline visualizations indicated the existence of counter rotating vortex pairs behind the Gurney Flap and that their rate of decay with respect to the Angle of attack was affected by the stagger angle at which the blades were arranged.

The effect of internal pressure in gas pores containing materials on their mechanical stability under shear

Metallic structures, produced by high pressure die-cast or powder bed fusion additive manufacturing techniques often contain gas pores. While under high triaxial stress states the effect of internal pressure can be superimposed on top of the applied stress field, thus resulting in a shift of the flow potential along the hydrostatic axis, under zero triaxiality deformation (i.e. shear) it is not quite obvious. The aim of this study is to analyse the overall mechanical behavior of such material when subjected to shear deformation. Two dimensional finite element calculations on a material containing a periodic array of pressurized voids are used for this analysis. It was found that with increasing internal pressure, the void's shape tends to remain elliptical and the appearance of stress concentrations, associated with the well know s-shape of sheared voids is delayed. This in turn, leads to a competition between two possible nucleation sites for strain localization. The combined effect of internal pressure and strain hardening was investigated through a parametric study and general conclusions are drawn.

Full Dimensional Potential Energy Function and Calculation of State-Specific Properties of the CO+N2 Inelastic Processes Within an Open Molecular Science Cloud Perspective.

A full dimensional Potential Energy Surface (PES) of the CO + N2 system has been generated by extending an approach already reported in the literature and applied to N2-N2 (Cappelletti et al., 2008), CO2-CO2 (Bartolomei et al., 2012), and CO2-N2 (Lombardi et al., 2016b) systems. The generation procedure leverages at the same time experimental measurements and high-level ab initio electronic structure calculations. The procedure adopts an analytic formulation of the PES accounting for the dependence of the electrostatic and non-electrostatic components of the intermolecular interaction on the deformation of the monomers. In particular, the CO and N2 molecular multipole moments and electronic polarizabilities, the basic physical properties controlling the behavior at intermediate and long-range distances of the interaction components, were made to depend on relevant internal coordinates. The formulated PES exhibits substantial advantages when used for structural and dynamical calculations. This makes it also well suited for reuse in Open Molecular Science Cloud services.

Full dimensional quantum mechanical calculations of the reaction probability of the H + NH3 collision based on a mixed Jacobi and Radau description.

The collision between hydrogen and ammonia is a benchmark system to study chemical elementary reactions with five atoms. In this work, we present a description of the system based on mixed Jacobi and Radau coordinates combined with the time-dependent wave packet method to study the H + NH3 reaction. The Radau coordinates are used to describe the reactive moiety NH2. A salient feature of this approach is that the present coordinates have a great advantage that a very small number of basis set functions can be used to describe the NH2 group. Potential-optimized discrete variable representation basis is applied for the vibrational coordinates of the reagent NH3. The reaction probabilities for several initial vibrational states are presented in this paper. The role of the different vibrational excitations on the reactivity is thoroughly described.

Effect of scan substrates on accuracy of 7 intraoral digital impression systems using human maxilla model.

This study aimed to determine how the accuracy of digital impressions was affected by four common dental substrates using seven prevalent IOS systems to scan the complete arch of a human maxilla. The Department of Oral Rehabilitation at the Medical University of South Carolina. A single cadaver maxilla. Seven digital intraoral impression systems were used to scan a freshly harvested human maxilla. The maxilla contained several teeth restored with amalgam and composite, as well as unrestored teeth characterized by enamel. Also, three teeth were prepared for full coverage restorations to expose natural dentin. An industrial grade metrology software program that allowed 3D overlay and dimensional computation compared deviations of the complete arch and its substrates on the test model from the reference model. Substrates were significantly different from each other when considering scan data as a whole, as well as when comparing IOS devices individually. Only PlanScan failed to reveal trueness differences between the different substrates, while only Emerald revealed precision differences between the substrates. Substrate type does impact the overall accuracy of intraoral scans with dentin being the most accurate and enamel being the least accurate. The four substrates scanned impacted the trueness of all IOS devices.

Few-body quantum method in a d-dimensional space

In this work we investigate the continuous confinement of quantum systems from three to two dimensions. Two different methods will be used and related. In the first one the confinement is achieved by putting the system under the effect of an external field. This method is conceptually simple, although, due to the presence of the external field, its numerical implementation can become rather cumbersome, especially when the system is highly confined. In the second method the external field is not used, and it simply considers the spatial dimension d as a parameter that changes continuously between the ordinary integer values. In this way the numerical effort is absorbed in a modified strength of the centrifugal barrier. Then the technique required to obtain the wave function of the confined system is precisely the same as needed in ordinary three dimensional calculations without any confinement potential. The case of a two-body system squeezed from three to two dimensions is considered, and used to provide a translation between all the quantities in the two methods. Finally we point out perspectives for applications on more particles, different spatial dimensions, and other confinement potentials.

Non-linear, time dependent target accuracy assessment algorithm for multi-physics, high dimensional nuclear reactor calculations

Safety analysis and design optimization depend on the accurate prediction of various reactor core responses. Model predictions can be enhanced by reducing the uncertainty associated with the responses of interest. Accordingly, an inverse problem analysis can be designed to provide guidance to determine the optimum experimental program to reduce the uncertainties in model parameters, e.g. cross-sections and fuel pellet-clad thermal conductivity, so as to reduce the uncertainties in constrained reactor core responses. This process is referred to as target accuracy assessment. In this work a nonlinear algorithm to determine an optimum experimental program has been developed and tested.The algorithm is based on the construction of surrogate model to replace the original model used to predict the core responses and uncertainties, therefore, enabling the target accuracy assessment to treat non-linearity within reasonable computational cost. Subspace based projection techniques are used to identify the influential degrees of freedom, which are then used to construct the surrogate model. Once constructed, the new computationally efficient surrogate model is used to propagate uncertainties via Monte Carlo sampling. Moreover, this work replaces the classical objective function used for nuclear data target accuracy assessment with another that factors in the financial gains of the target accuracy assessment results and replaces [or can supplement] differential experiments with many times more readily available integral experiments.Finally, the proposed algorithm is applied on a 3-dimensional fuel assembly depletion problem with thermal-hydraulics feedback using the VERA-CS core simulator. Specifically, CASL Progression Problem Number 6 is the illustrative problem employed which resembles a pressurized water reactor fuel assembly.

Droplet size prediction model based on the upper limit log-normal distribution function in venturi scrubber

Abstract Droplet size and distribution are important parameters determining venturi scrubber performance. In this paper, we proposed physical models for a maximum stable droplet size prediction and upper limit log-normal (ULLN) distribution parameters. For the proposed maximum stable droplet size prediction model, a Eulerian-Lagrangian framework and a Reitz-Diwakar breakup model are solved simultaneously using CFD calculations to reflect the effect of multistage breakup and droplet acceleration. Then, two ULLN distribution parameters are suggested through best fitting the previously published experimental data. Results show that the proposed approach provides better predictions of maximum stable droplet diameter and Sauter mean diameter compared to existing simple empirical correlations including Boll, Nukiyama and Tanasawa. For more practical purpose, we developed the simple, one dimensional (1-D) calculation of Sauter mean diameter.

Analysis and Simulation Study on Economy of Biodiesel Engine

Reducing harmful diesel emissions while maintaining high thermal efficiency has always been hot research point in diesel technology field. The combining CAE technology and testing methods has been adopted for a small high-speed turbocharged CR diesel engine, one dimensional models were established in order to explore and analyse the effects of biodiesel on engine power performance and economic performance. The one dimensional calculation process of biodiesel engine indicates that calculation performance indexes of the established model can agree with the testing data, and the model is accurate. The one dimensional calculation process of biodiesel engine indicates BSFC is higher than that of diesel, but the BSEC is lower than the case. Biodiesel has superior economic performance. The results and approaches can give a theory and application value for the development of biodiesel engine.

Mapping parties in a multidimensional European political space: A comparative study of the EUvox and euandi party position data sets

This study compares the spatial positioning of over 200 political parties across 28 European Union (EU) member states in two cross-national voting advice applications (VAAs) developed for the 2014 European elections: EUvox and euandi. We find that the two VAAs show highly similar results in terms of party positioning on the cultural liberal-conservative and pro-anti EU dimensions, while economic left–right placements converge less, especially concerning right-wing parties. Our analyses reveal that the higher overlap on the cultural and EU dimensions is a result, at least partially, of the inclusion of similar items used to measure these concepts, while most of the systematic divergence between the two VAAs in left–right placements stems from problematic issue-statements used in the dimensional calculations. We demonstrate how certain items can cause bias in the placements of specific party families by (1) not aligning with other statements that measure the same latent construct; (2) tapping into other latent constructs, in addition to the one they are supposed to measure; and (3) not inducing sufficient polarization between parties.

Conformal mapping approach to dipole shim design

Passive shims are often used to reduce the size and cost of room-temperature magnetic dipoles. In this paper we revisit an analytic approach to the problem of optimum shim design, and we extend it by taking into consideration the effect of magnetic saturation. We derive an abacus curve to determine optimum shim dimensions as a function of the desired dipole nominal field. We show that, for nominal fields below 1.2T, a pole with such shims can be made at least one half gap height narrower than a pole without. We discuss the range of validity of this approach and verify its predictions using 2 and 3-dimensional finite-element calculations.

Free Energy Calculation of Transmembrane Ion Permeation: Sample with a Single Reaction Coordinate and Analysis along Transition Path.

A single reaction coordinate is designed to perform umbrella sampling for the water-chain-assist transmembrane permeation processes of ions and highly polar groups. In these permeation processes, there are three types of configuration changes including deformation of both leaflets of the lipid bilayer, formation of a water chain across the bilayer, and translocation of the ion through the bilayer. Due to the complexity of the permeation process, multiple reaction coordinates and expensive high dimensional free energy calculations have been used in previous studies. Our single reaction coordinate can be used to obtain sample data of the entire permeation process, which significantly reduces the computational cost in free energy calculations. We show that one-dimensional umbrella sampling along the new reaction coordinate can be used to obtain continuous sample data roughly along the minimum free energy path (MFEP) on the phase plane of the two components of the new reaction coordinate. Along the MFEP, a one-dimensional bin-segmentation of the sample data is then used to calculate the potential of mean force accurately by the newly developed free energy analysis method: weighted least-square analysis method (Welsam). Our work not only proposes a useful reaction coordinate to obtain sample data for water-chain assist transmembrane permeation processes but also establishes a general methodology for one-dimensional free energy calculations with bin-segmentation along the transition path in multiple dimensional phase space.

Deployment of a Matrix Element Method code for the ttH channel analysis on GPU’s platform

The observation of the associated production of the Higgs boson with two top quarks in proton-proton collisions is one of the highlights of the LHC Run 2. Driven by the theoretical description of the physics processes, the Matrix Element Method (MEM) consists in computing a probability that an event is compatible with the signal hypothesis (ttH) or with one of the background hypotheses. It is a powerful classifying tool requiring high dimensional integral computations. The deployment of our MEM production code on GPU’s platform will be described. What follows will focus on the adaptation of the main components of the computations in OpenCL kernels, namely the Magraph matrix element code generator, VEGAS, and LHAPDF. Finally, the gain obtained on GPU’s platforms compared with classical CPU’s platforms will be assessed.