Complete Calculation Research Articles

A new method to improve the real-time performance of aero-engine component level model

Abstract In order to improve the real-time performance of aero-engine component-level models, an automatic fast positioning interpolation method is proposed. Based on the maximum parameter slope, this method can automatically determine the interpolation cut in point, change the disadvantage of low efficiency of traditional sequential interpolation from the starting point, effectively reduce the interpolation interval, thus greatly improving the efficiency of interpolation. The method is applied to the calculation of gas thermodynamic parameters and the interpolation of the characteristic of rotating parts ,so as to ameliorate the real-time performance of the single-stage flow path calculation of the component-level model. Simulation results show that, compared with the traditional method, the method proposed in this paper improves the fan characteristic calculation efficiency by 47.5%, reduces the time of single complete flow calculation by 74.3% when the dynamic and steady-state accuracy changes are less than 0.4%, which greatly improves the real-time performance of the component-level model.

A new method to improve the real-time performance of aero-engine component level model

Abstract In order to improve the real-time performance of aero-engine component-level models, an automatic fast positioning interpolation method is proposed. Based on the maximum parameter slope, this method can automatically determine the interpolation cut in point, change the disadvantage of low efficiency of traditional sequential interpolation from the starting point, effectively reduce the interpolation interval, thus greatly improving the efficiency of interpolation. The method is applied to the calculation of gas thermodynamic parameters and the interpolation of the characteristic of rotating parts ,so as to ameliorate the real-time performance of the single-stage flow path calculation of the component-level model. Simulation results show that, compared with the traditional method, the method proposed in this paper improves the fan characteristic calculation efficiency by 47.5%, reduces the time of single complete flow calculation by 74.3% when the dynamic and steady-state accuracy changes are less than 0.4%, which greatly improves the real-time performance of the component-level model.

Combined stability of cone-cylinder transition subjected to axial compression and external pressure

This paper examines the buckling behaviour of unstiffened mild steel cone-cylinder assembly under (i) axial compression and (ii) combined loading (i.e., axial compression and external pressure). Experimental results on ten (10) laboratory scaled axially compressed cone-cylinder models and their accompanying numerical predictions of collapse load are provided. The tested models are assumed to have the following range of geometric parameter: rcone/rcyl = 0.565–0.721, rcyl/t = 72.17–72.73, β = 8.536° – 16.69° and a constant wall thickness, t = 1.0 mm. Result confirms the repeatability of the experimental data. Besides that, there is a good agreement between experimental and numerically predicted collapse load with discrepancy calculated to be within 10%. Furthermore, numerical analysis of stability domains for cone-cylinder assembly subjected to simultaneous load actions of axial compression and external pressure was calculated for a range of geometrical parameters of: (i) 50 < rcyl/t < 400 and (ii) 10° < β < 30°. For comparison purpose, the equivalent cylinder approach was also deployed to complete calculation based on ASME code case 2286-2. For the case of dimensionless radius-to-thickness ratio, rcyl/t, the result confirms that the ASME code case 2286-2 is unsafe in designing the cone-cylinder shell with rcyl/t > 400. Whereas, for the case of different cone angle, β, it can be said that the ASME code case 2286-2 may perhaps be safe to use in designing the cone-cylinder shell with β < 20°. In addition, the current analysis confirms that increasing the (a) dimensionless radius-to-thickness ratio, rcyl/t and (b) increasing the cone angle, β, may further shrink the combined stability plot. Finally, imperfect cone-cylinder shell under combined loading confirms that (i) the shell is remarkably sensitive at the pressure dominant region compared to the force dominant region and (ii) the location of dimple/dent imperfection at cylinder mid-section proves to be the worst-case scenario.

Improved neutrino-nucleon interactions in dense and hot matter for numerical simulations

Neutrinos play an important role in compact star astrophysics: neutrino-heating is one of the main ingredients in core-collapse supernovae, neutrino-matter interactions determine the composition of matter in binary neutron star mergers and have among others a strong impact on conditions for heavy element nucleosynthesis and neutron star cooling is dominated by neutrino emission except for very old stars. Many works in the last decades have shown that in dense matter medium effects considerably change the neutrino-matter interaction rates, whereas many astrophysical simulations use analytic approximations which are often far from reproducing more complete calculations. In this work we present a scheme which allows to incorporate improved rates, for charged current interactions, into simulations and show as an example some results for core-collapse supernovae, where a noticeable difference is found in the location of the neutrinospheres of the low-energy neutrinos in the early post-bounce phase.

Chemistry in a cup of coffee: Adapting an online lab module for teaching specific heat capacity of beverages to health sciences students during the COVID pandemic.

The present pandemic has hurled organizations into a new social "norm"-and academia is not exempt. As a result, a novel pedagogy has evolved, demanding mechanisms of social distance teaching and learning be developed. This new era in education has learning institutions acquiring, adapting or even designing online STEM labs for physical science courses-replacing face-to-face teaching laboratory settings. The difficulty of designing science practicum that promotes student engagement and relates scientific principles to "real life" has heightened as we shift to more online instruction. Therefore, a necessity to develop contemporary methods of promoting student engagement and participation in an online learning environment has become apparent. Here, a virtual lab course designed for health science majors, utilized an online lab module and, with the use of a learning management system, adapted it to illustrate the principles of specific heat capacity in "real life": hot coffee. Students enrolled in the lab course were able to perform a virtual lab, complete calculations, compare calculated and experimental values, and relate the experimental chemistry topics to healthcare in a lab report. Following the lab experience, students completed an anonymous and voluntary qualitative survey in which they recommended this lab exercise for future classes.

N-jettiness beam functions at N3LO

We present the first complete calculation for the quark and gluon N-jettiness ( {mathcal{T}}_N ) beam functions at next-to-next-to-next-to-leading order (N3LO) in perturbative QCD. Our calculation is based on an expansion of the differential Higgs boson and Drell-Yan production cross sections about their collinear limit. This method allows us to employ cutting edge techniques for the computation of cross sections to extract the universal building blocks in question. The class of functions appearing in the matching coefficents for all channels includes iterated integrals with non-rational kernels, thus going beyond the one of harmonic polylogarithms. Our results are a key step in extending the {mathcal{T}}_N subtraction methods to N3LO, and to resum {mathcal{T}}_N distributions at N3LL′ accuracy both for quark as well as for gluon initiated processes.

LAST PLANNER SYSTEM (LPS) IMPLEMENTATION ON JAKARTA-CIKAMPEK II ELEVATED TOLL ROAD PROJECT

In construction industry, its implementation of the construction has its own constraints. A good management or project management system is needed to minimize the risk of these constraints. The latest project management concept that has proven more effective and efficient is Last Planner System method. This study aims to investigate how the implementation of Last Planner System works on Jakarta-Cikampek II Elevated Toll Road Project. With the evaluation of weekly job evaluations using PPC (Percent Plan Completed) and Pareto Variance Constraint analysis, the constraint issues of this project will be identified. Then they are followed up to find the right solution in handling the constraints. The research method is done by conducting literature study, problem formulation, followed by implementing LPS method, which is through work flow control such as phase and pull plan, lookahead plan, constrain analysis, daily huddles, PPC (Percent Plan Completed) calculation, Pareto Chart analysis with data variation of issues that have been obtained. The results show that the average PPC weekly project is 83.04% and the most influential reason that must be concerned its priority is submittals.

Craters on Charon: Impactors from a Collisional Cascade Among Trans-Neptunian Objects

Abstract We consider whether equilibrium size distributions from collisional cascades match the frequency of impactors derived from New Horizons crater counts on Charon. Using an analytic model and a suite of numerical simulations, we demonstrate that collisional cascades generate wavy size distributions; the morphology of the waves depends on the binding energy of solids and the collision velocity v c . For an adopted minimum size of solids, = 1 μm, and collision velocity v c = 1–3 km s−1, the waves are rather insensitive to the gravitational component of . If the bulk strength component of is for particles with radius r, size distributions with small Q s are much wavier than those with large Q s ; systems with e s ≈ −0.4 have stronger waves than systems with e s ≈ 0. Detailed comparisons with the New Horizons data suggest that a collisional cascade among solids with a bulk strength intermediate between weak ice and normal ice produces size distributions fairly similar to that of impactors on Charon. If the surface density Σ of the protosolar nebula varies with semimajor axis a as Σ ≈ 30 g cm−2 (a/1 au)−3/2, the timescale for a cascade to generate an approximate equilibrium is 100–300 Myr at 45 au and 10–30 Myr at 25 au. Although it is necessary to perform more complete evolutionary calculations of the Kuiper Belt, collisional cascades are a viable model for producing the size distribution of solids that impacted Charon throughout its history.

Multipolar scattering of subwavelength interacting particles: Extraction of effective properties between transverse and longitudinal optical modes

The general concern of this investigation is the extraction of the effective electromagnetic properties of agglomerates of randomly located particles, which are small compared to the wavelength. The focus is on the spectral window ranging from the transverse phonon to the longitudinal phonon frequencies, in which resonances may be excited. In this frequency domain, it is shown that limiting the problem to bare dipole-dipole interactions leads to inaccurate calculations of the electromagnetic fields, resulting in a doubtful extraction of the effective properties. We perform the complete electromagnetic calculation by taking into account the higher multipole orders that are activated when the agglomerates are illuminated. Several results, which are not usually observed outside the frequency range highlighted here, are revealed by means of extensive numerical simulations. In particular, we evidence large deviations compared to the predictions provided by the effective medium theories, while we find that the volume of the microstructures (each one with a different internal geometry) that are used to average the fields must be unusually large to avoid a bias in the determination of the effective properties. Furthermore, the evolution of the incoherent component of the fields between the two optical phonon modes is investigated.

Exploring physical properties of compact stars in f(R,T)-gravity: An embedding approach

Solving field equations exactly in gravity is a challenging task. To do so, many authors have adopted different methods such as assuming both the metric functions and an equation of state (EoS) and a metric function. However, such methods may not always lead to well-behaved solutions, and the solutions may even be rejected after complete calculations. Nevertheless, very recent studies on embedding class-one methods suggest that the chances of arriving at a well-behaved solution are very high, which is inspiring. In the class-one approach, one of the metric potentials is estimated and the other can be obtained using the Karmarkar condition. In this study, a new class-one solution is proposed that is well-behaved from all physical points of view. The nature of the solution is analyzed by tuning the coupling parameter , and it is found that the solution leads to a stiffer EoS for than that for . This is because for small values of , the velocity of sound is higher, leading to higher values of in the curve and the EoS parameter . The solution satisfies the causality condition and energy conditions and remains stable and static under radial perturbations (static stability criterion) and in equilibrium (modified TOV equation). The resulting diagram is well-fitted with observed values from a few compact stars such as PSR J1614-2230, Vela X-1, Cen X-3, and SAX J1808.4-3658. Therefore, for different values of , the corresponding radii and their respective moments of inertia have been predicted from the curve.

Excitons in CdTe/ZnTe heterostructure with atomically thin CdTe layers

Heterostructures with atomically thin double quantum wells based on CdTe/ZnTe are investigated by optical spectroscopy (photoluminescence and reflectivity methods) as a function of temperature and density of excitation. Heavy and light exciton luminescence lines are observed with comparable intensities and different temperature behaviors (they cross each other at about 65° K). All these features agree with a complete calculation that takes into account both a very small chemical band offset for such monolayer CdTe inclusions in the ZnTe matrix (namely, 2%), and, consequently, the importance of Coulombic interaction in these double quantum wells.

First evidence of inertial modes in γ Doradus stars: The core rotation revealed

The advent of space photometry with CoRoT and Kepler has allowed for the gathering of exquisite and extensive time series for a wealth of main-sequence stars, including γ Doradus stars, whose detailed seismology was not achievable from the ground. γ Doradus stars present an incredibly rich pulsation spectra, with gravito-inertial modes, in some cases supplemented with δ Scuti-like pressure modes – for the hybrid stars – and, in many cases, with Rossby modes. The present paper aims to show that in addition to these modes which have been established in the radiative envelope, pure inertial modes that are trapped in the convective core can be detected in Kepler observations of γ Doradus stars thanks to their resonance with the gravito-inertial modes. We started by using a simplified model of perturbations in a full sphere of uniform density. Under these conditions, the spectrum of pure inertial modes is known from analytical solutions of the so-called Poincaré equation. We then computed coupling factors, which helped select the pure inertial modes which interact best with the surrounding dipolar gravito-inertial modes. Using complete calculations of gravito-inertial modes in realistic models of γ Doradus stars, we are able to show that the pure inertial and gravito-inertial resonances appear as “dips” in the gravito-inertial mode period spacing series at spin parameters that are close to those predicted by the simple model. We find the first evidence of such dips in the Kepler γ Doradus star KIC 5608334. Finally, using complete calculations in isolated convective cores, we find that the spin parameters of the pure inertial and gravito-inertial resonances are also sensitive to the density stratification of the convective core. In conclusion, we have discovered that certain dips in gravito-inertial mode period spacings that have been observed in some Kepler stars are, in fact, signatures of resonances with pure-inertial modes that are trapped in the convective core. This holds the promise that it would be possible to finally access the central conditions, namely, the rotation and density stratification, of intermediate-mass stars in the main sequence.

Mass spectra of heavy pseudoscalars using instantaneous Bethe\u2013Salpeter equation with different kernels

We solved the instantaneous Bethe–Salpeter equation for heavy pseudoscalars in different kernels, where the kernels are obtained using linear scalar potential plus one gluon exchange vector potentials in Feynman gauge, Landau gauge, Coulomb gauge and time-component Coulomb gauge. Since we cannot give a complete QCD-based calculation, the results are gauge dependent. We compared the obtained mass spectra of heavy pseudoscalars between different kernels, found that using the same parameters we obtain the smallest mass splitting in time-component Coulomb gauge, the similar largest mass splitting in Feynman and Coulomb gauges, middle size splitting in Landau gauge.

Revisiting supernova constraints on a light CP-even scalar

A light CP-even Standard Model (SM) gauge-singlet scalar S can be produced abundantly in the supernova core, via the nucleon bremsstrahlung process N N → N N S, due to its mixing with the SM Higgs boson. Including the effective S coupling to both nucleons and the pion mediators, we evaluate the production amplitude for the S particle and point out a key difference with the well-known light CP-odd scalar (axion) and vector boson (dark photon) cases. Taking the subsequent decay and re-absorption of S into account, we present a complete calculation of the energy loss rate for the S particle. We then use the SN1987A luminosity constraints to derive an updated limit on the mixing of the scalar S with the SM Higgs boson. We find that the mixing angle sinθ with the SM Higgs is excluded only in the narrow range of 3.5 × 10−7 to 2.5 × 10−5, depending on the scalar mass up to the two-pion threshold, beyond which the supernova limit disappears. This result has important consequences for the laboratory searches for light scalars.

Improvement of indoor air quality by way of using decentralised ventilation

This study contains an analysis of indoor air quality in an office building. The analysis was carried out in real conditions. The purpose of conducted research was to determine façade-mounted ventilation unit efficiency to reduce pollution. The air was supply and exhaust from the room cycles lasting 2 min, 4 min and 10 min. The experimental research and calculation with use of tracer gas were conducted for determination of the air change rate. Carbon dioxide was used as tracer gas. The results of completed studies and calculations have shown that decentralised façade ventilation systems sufficiently reduces the concentration of gaseous pollutants. They keep the room temperature in the range of 21–22 °C and the relative humidity 28–39%. Cyclic air supply and exhaust guarantees hourly air change rate sufficient to dilute pollution. For the shortest cycle the experimental value of the air change rate equalled 2.3 h−1, and the calculated value equalled 2.2 h−1. For the longest cycle both values equalled 2.7 h−1. The conducted statistical analysis showed that the greatest average feature value of the reduction characteristic (reduction of carbon dioxide concentration) can be expected for the setting characteristic (lasting time of cycle) 10 min.

Localizing the E2 page of the Adams spectral sequence

There is only one nontrivial localization of $\pi_*S_{(p)}$ (the chromatic localization at $v_0=p$), but there are infinitely many nontrivial localizations of the Adams $E_2$ page for the sphere. The first non-nilpotent element in the $E_2$ page after $v_0$ is $b_{10}\in \mathrm{Ext}_A^{2p(p-1)-2}(\mathbb{F}_p,\mathbb{F}_p)$. We work at $p=3$ and study $b_{10}^{-1}\mathrm{Ext}_P(\mathbb{F}_3,\mathbb{F}_3)$ (where $P$ is the algebra of dual reduced powers), which agrees with the infinite summand $\mathrm{Ext}_P(\mathbb{F}_3,\mathbb{F}_3)$ of $\mathrm{Ext}_A(\mathbb{F}_3,\mathbb{F}_3)$ above a line of slope ${1\over 23}$. We compute up to the $E_9$ page of an Adams spectral sequence in the category $\mathrm{Stable}(P)$ converging to $b_{10}^{-1}\mathrm{Ext}_P(\mathbb{F}_3,\mathbb{F}_3)$, and conjecture that the spectral sequence collapses at $E_9$. We also give a complete calculation of $b_{10}^{-1}\mathrm{Ext}_P^*(\mathbb{F}_3,\mathbb{F}_3[\xi_1^3])$.

Revealing the two-electron cusp in the ground states of He and H2 via quasifree double photoionization

We report on kinematically complete measurements and ab initio non-perturbative calculations of double ionization of He and H2 by a single 800 eV circularly polarized photon. We confirm the quasifree mechanism of photoionization for H2 and show how it originates from the two-electron cusp in the ground state of a two-electron target. Our approach establishes a new method for mapping electrons relative to each other and provides valuable insight into photoionization beyond the electric-dipole approximation.

Nonradiative α7m QED effects in the Lamb shift of helium triplet states

Theoretical predictions for the Lamb shift in helium are limited by unknown quantum electrodynamic effects of the order $\alpha^7m$, where $\alpha$ is the fine-structure constant and $m$ is the electron mass. We make an important step towards the complete calculation of these effects by deriving the most challenging part, which is induced by the virtual photon exchange between all three helium particles, the two electrons, and the nucleus. The complete calculation of the $\alpha^7m$ effect including the radiative corrections will allow comparing of the nuclear charge radii determined from the electronic and muonic helium atoms and thus provide a stringent test of the Standard Model of fundamental interactions.

PRORAČUN KONSTRUKCIJE ČELIČNE HALE SA KRANSKOM STAZOM I UPOREDNA ANALIZA KRANSKE STAZE PREMA SRPS STANDARDU I EVROKODU

U radu je dat proračun čelične hale sa kranskom stazom prema standardu Evrokod. Izvršen je i prikazan cjelokupan statički proračun svih konstruktivnih elemenata kao i dimenzionisanje istih praćeno neophodnom grafičkom dokumentacijom (detalji čelika, detalji veza, detalji armiranja). Eksperimentalni dio rada se odnosi na uporednu analizu kranske staze prema standardu SRPS i prema Evrokodu.

Predictive Analysis for Radiated Electromagnetic Disturbance in MMC-HVDC Valve Hall

The radiated electromagnetic interference (EMI) in the valve hall of the modular multilevel converter (MMC) station must be limited below a certain value to ensure the normal operation of the equipment and the safety of the engineers. In this paper, a method for predicting the radiated EMI is proposed, which takes all the necessary factors, such as the physics-based characteristics for IGBT module, sub-module topology, and converter space structure into consideration. This method involves the improved physical model of semiconductor devices, which discards the non-physical feedback parameter introduced by some previous research. At the same time, through the decoupling of the submodule and the bridge arm circuit, the order of the large-scale system is reduced so that the sub-modules can be calculated in parallel, greatly reducing the overall calculation burden of the model and accelerating the nonlinear small time-step simulation. The wideband characteristics of the converter valve tower are fully considered, with each of the bridge arms regarded as a two-port network with independent sources. The parameter integration and distribution process can also achieve complete parallel calculation. The converter valve tower is modeled as a complex antenna structure with the output voltage of each sub-module as the excitation, the calculation of near-field radiation intensity for the converter valve tower is performed in Alteir FEKO. The measurement conducted inside an actual 49-level converter station verifies the accuracy of the model.