bluuebunny/crossref_metadata_2025_split huggingface dataset:
Economic feasibility study for artificial lighting of microalgal flat-panel photobioreactors
Authors: Kratky L. , Jirout T. , Belohlav V. 
Published: February 2023

AbstractLightning belongs among critical process parameters that significantly affect growth and microalgal yield in photobioreactors. Sunshine or artificial lighting is applied to irradiate photobioreactors. Nevertheless, sunshine lighting is limited by locality and weather conditions. On the contrary, there is a typical demand for nonstop or 8000 annual working hours for industrial biorefineries using photobioreactors as an economic point of view. Thus the paper scopes to evaluate the fundamental economic feasibility of artificial lightning provided by electric energy from fossil fuels, renewable energy systems, or their mutual combinations. The economic feasibility is discussed concerning local annual sunshine hours for a model 1-ha microalgae cultivation plant. It was found that combined sunlight, solar energy- and electric energy-based artificial lighting has a significant positive effect on the economic behavior of a model biorefinery. The mutual combination of sunshine, solar energy- and electric artificial energy-based light evinces a profit increase of 2.18 for microalgal powder, 3.09 for microalgal lipids and 4.11 for microalga carotenoids production technologies all compared only to sun lighted photobioreactors. Nevertheless, capital investments in artificial lightings, solar systems, or photobioreactors, and high operating expenses represent the dominant risk factors of the discussed microalgal biorefinery. Developing cheap and reliable artificial lighting systems, solar and energy storage systems, and improving process characteristics of microalgal cultivation (process stability, high concentrated suspension in thin layer photobioreactors avoiding biofilm formation) were identified as the essential research needs and challenges to improve the economic feasibility of artificially lighted microalgal biorefinery.
Bactericide gold decorated mulberry fibers for therapeutic and non-therapeutic tenacities
Authors: Amna Touseef 
Published: February 2023

AbstractIn this study an approach was made to efficaciously synthesize gold decorated mulberry fibers by a facetious dip coating procedure. Assortments of inorganic compounds are being employed to impart antimicrobial properties to fabrics and textiles. Earlier workers have used gold as coloring agent for cotton and yarn etc. Herein, for the first time an attempt was made to liftoff a progressive textile conjured of gold and mulberry fibers which will be exploited for fabrication of antimicrobial stuffs for diverse medical and non-medical uses. The morphology, physicochemical and antibacterial characteristics of gold decorated mulberry fibers were scanned via X-ray diffraction (XRD), Scanning electron microscope (SEM), Electron probe microanalysis (EPMA), Fourier transform infrared (FTIR) and antibacterial testing. The average size of gold particles was between 1.9 and 3 μm. The even distribution of Au on mulberry fibers was corroborated by SEM, and the results of XRD and FTIR analysis confirmed integration of nanogold in mulberry. The XRD data of Au blended fibers revealed no change in peak location, implying that gold coating has no effect on mulberry fiber structure. Gold decorated mulberry has a little higher intensity and a slight change in peak position toward higher wavenumber, which could be related to functionalization or interaction of gold particles with mulberry fibers. These gold incapacitated mulberry fibers shown out antibacterial activity against illustrative bacterium E. coli. Thus our study provides optimistic indications to pick up mulberry fibers decked with nanogold as prime material for fabrication of forthcoming antimicrobial materials for therapeutic and non-therapeutic tenacities.
Exactly solvable urn models under random replacement schemes and their applications
Authors: Inoue Kiyoshi 
Published: February 2023

AbstractWe examine urn models under random replacement schemes, and the related distributions, by using generating functions. A fundamental isomorphism between urn models and a certain system of differential equations has previously been established. We study the joint distribution of the numbers of balls in the urn, and determined recurrence relations for the probability generating functions. The associated partial differential equation satisfied by the generating function is derived. We develop analytical methods for the study of urn models that can lead to perspectives on urn-related problems from analytic combinatorics. The results presented here provide a broader framework for the study of exactly solvable urns than the existing framework. Finally, we examine several applications and their numerical results in order to demonstrate how our theoretical results can be employed in the study of urn models.
Politics, not Vulnerability: Republicans Discriminated against Chinese-born Americans throughout the COVID-19 Pandemic
Authors: Abascal Maria , Makovi Kinga , Xu Yao 
Published: February 2023

AbstractAsian Americans became targets of increasingly hostile behavior during the COVID-19 pandemic. What motivated this? Fears of contagion arising from a behavioral immune system may have motivated hostility toward Asian Americans, especially among those Americans vulnerable to COVID-19. Additionally, stigmatizing rhetoric from right-wing figures may have legitimated anti-Asian behavior among those Americans who held stronger anti-Asian sentiments to begin with or who were more receptive to right-wing rhetoric. We explore these possibilities using a behavioral game with a representative sample of Americans at two points: in May and October 2020. Participants were partnered with a U.S.- or Chinese-born American in a give-or-take dictator game. The average American discriminated against Chinese-born Americans in May but not October 2020, when China was no longer a COVID-19 hotspot. But among Republicans, who may have held stronger anti-Asian sentiments to begin with and who were likely more receptive to right-wing rhetoric, discrimination—that is, differential treatment—was both stronger in May compared to non-Republicans and persisted into October 2020. Notably, Americans who were more vulnerable to COVID-19 were not especially likely to discriminate.
Active control to augment rotor lead-lag damping
Authors: Kessler C. , Reichert G. 
Published: February 2023

AbstractHingeless and bearingless rotor designs are today well accepted for modern helicopters. Continued development, however, revealed some deficiencies in the area of aeromechanical stability and vibration. In general there is a good basic understanding of how to avoid these instabilities. But since it becomes more and more desirable to focus rotor design on aerodynamic features and flight performance, these aeromechanical instabilities gain new importance due to the difficulties to provide the required damping.Since all rotor concepts suffer from the lack of sufficient natural lead-lag or inplane damping most designs in use show artificial lead-lag dampers to overcome aeromechanical instabilities. Additionally, active control offers the possibility for an artificial stabilisation of aeromechanical instabilities. Meanwhile, many research activities focus on active control to augment rotor lead-lag damping and many authors demonstrate the potential inherent in this approach.
Satellite attitude slew manoeuvres using inverse control
Authors: Mclnnes C.R. 
Published: February 2023

AbstractInverse dynamics is investigated as an efficient means of generating large angle satellite attitude slew manoeuvres. The required slew manoeuvres are specified using high order polynomials which result in a smooth control torque profile. Such smooth torque profiles are of importance in avoiding excitation of elastic modes of the satellite structure. In addition, the polynomial functions may be used to define a slew trajectory between arbitrary initial and final states allowing track-to-track manoeuvres. To compensate for uncertainties in the satellite dynamics, the inverse control is extended to include feedback linearisation about the nominal reference trajectory. It is shown that for rest-to-rest slew manoeuvres the resulting composite control is robust to uncertainties in the satellite inertia matrix and to actuator degradation. In addition, it is shown that complex paths may be generated through the use of high order polynomial functions which contain all the information required to enforce user defined constraints and boundary conditions in a compact, computationally efficient form.
Through thickness fatigue failure of fibre-reinforced composites
Authors: Wisnom M. R. , Jones M. I. 
Published: February 2023

AbstractSimple straight and curved beams of unidirectional glass-epoxy were tested in fatigue to investigate failure under overall interlaminar tension and shear combined with local stresses at cut plies. Similar behaviour was observed as under static loading, with overall and local stresses interacting to cause delamination. When normalised, all the results lay close to, or above, a line determined from previous tension tests on specimens with cut plies, suggesting that this could be used as the basis for through thickness fatigue strength calculations.
The feasibility and benefits of dynamic reconfiguration in integrated modular avionics
Authors: Johnson D. M. , Omiecinski T. A. 
Published: February 2023

AbstractIntegrated modular avionics has been proposed as a means of reducing avionics development and operating costs, by standardisation of avionics hardware and non-application-specific software. With the introduction of integrated modular avionics, there is the possibility of dynamically reconfiguring available resources, to preserve the most critical functions, when failures occur. This paper examines the feasibility of dynamic reconfiguration within the system architectures proposed by ARINC 651 and assesses the potential benefits. The analysis shows that at least two of the architectures proposed by ARINC 651 are well suited to reconfiguration and that although there are certification problems that must be considered, these problems do not appear intractable. Significant benefits, in terms of reduced redundancy, improved availability and higher levels of safety can potentially be obtained. The paper also shows that reconfiguration is only required locally, within a cabinet, and that large benefits are still obtainable even with relatively small cabinet sizes. This reduces the complexity and cost of any reconfiguration scheme and increases flexibility so that any reconfiguration scheme developed can be easily adapted to differing aircraft requirements. The development of an autonomous reconfiguration scheme, in which individual modules determine their own function is particularly attractive, as it can offer reduced susceptibility to common mode failure, and provides fault tolerance within the reconfiguration process itself.
Variable cycle jet engines for a Mach 2·7 supersonic civil transport
Authors: Aleid L. , Pilidis P. 
Published: February 2023

AbstractThe aim of the work outlined in this paper is to compare three different variable cycle jet engine concepts for future SSTs. These engines are: the turbofan-turbojet, the mid-tandem fan engine and the double bypass engine. The comparison is carried out on the basis of unin-stalled and installed performance, handling and sizing issues.This preliminary analysis compares SFC, size, variable geometry and cycle changes for each engine. The installed performance was estimated by calculating the air friction, the pre-entry and the afterbody drags, together with the wave drag due to the shock waves. A sizing calculation was carried out for the whole nacelle. The uninstalled and installed fuel bill, for two standard missions, is also estimated.These preliminary results indicate that the turbofan-turbojet and the mid-tandem fan engines are quite similar in terms of general suitability. The mid-tandem fan appears to be an attractive proposition from the point of view of sizing, however, this comes with a small penalty in fuel consumption. The present double bypass engine was found to be the least attractive for the application, although the differences are small.
Some aspects of centrifugal fan characteristics in blower windtunnels
Authors: Johnson A. E. , Hancock P. E. 
Published: February 2023

AbstractMeasurements have been made in the exit flows of the fan, diffuser, settling chamber and contraction of a low speed blower windtunnel driven by a centrifugal fan. A velocity deficit and streamwise vortex were observed at the diffuser exit when the fan was operating at less than about 0·9 of maximum efficiency but not when operating above. Unacceptably large unsteadiness (-0·7% rms) occurred at low speeds when the fan speed was increased from rest, but not when the fan speed was decreased from full speed. This unsteadiness was at the rotor frequency, and appears to have been caused by laminar boundary layer separation on one or more adjacent aerofoil blades, coupled with slight asymmetry in the rotor. Unsteadiness at the rotor frequency and of comparable magnitude has also been seen in another, larger fan, but was not eliminated in the same way. Attaining high quality flow is likely to require careful attention to the characteristics of individual fans.
A note on the potential contribution of wing-body interference drag to the total drag of an aircraft
Authors: Bernstein L. 
Published: February 2023

SummaryThe implications of a rise in the pressure drag of a wing near its junction with a fuselage are examined. Based on some data measured for a swept-wing-plate junction, in which the wing was of NACA 0015-profile normal to its leading edge and swept back at 20°, it is found that there is a potential penalty of order 1% of the total aircraft drag in the cruise condition.
Efficient lift enhancement of a blunt edged delta wing
Authors: Traub L. W. 
Published: February 2023

AbstractA windtunnel study was undertaken to determine the effectiveness of leading edge vortex plates in enhancing the lifting abilities of a blunt edged delta wing. In the investigation, vortex plates were attached to both the upper and lower surfaces of the leading edge. Various positions of the vortex plates with respect to the wing's leading edge were evaluated. The results indicate that a vortex plate located on the upper surface of the wing is capable of increasing lift so as to be comparable to a similar sharp edged wing, whilst reducing drag through some retained leading edge thrust. The increase in zero lift drag associated with vortex plate attachment tends to limit potential performance improvements. A vortex plate mounted on the lower wing surface decreased lift slightly compared to the blunt wing. However, drag was found to decrease markedly.
Flight investigations of the effect of yaw on the intake and fan nozzle flow of a natural laminar flow nacelle
Authors: Riedel H. , Sitzmann M. 
Published: February 2023

AbstractTwo major technologies in aeronautics promise substantial improvements in the fields of economy and ecology. One is laminar flow technology and the other arises from new developments related to aircraft turbofan engines. The trend in turbofan engine development is towards engines possessing higher bypass ratios. This, however, entails larger engine dimensions, leading not only to an increase in the skin friction drag but also to negative engine-airframe interactions. As a consequence, the need for laminar flow nacelles becomes all the more important as part of the general process of engine-air-frame integration optimisation for advanced transport aircraft.This paper deals with some results obtained from flight tests with a laminar flow nacelle demonstrator and specifically addresses the topic of aerodynamics of intakes and nozzles. The results described relate to a European collaborative programme in which a natural laminar flow (NLF) nacelle was flight tested. Results of the effect of the angle of yaw on the static pressure distribution on the fan cowl including the intake of an NLF nacelle are presented for the maximum cruise flight condition. At zero yaw, a comparison of Euler calculations with flight test data is made. Measured flow variables of the fan nozzle flow directly downstream of the fan nozzle exit, exemplified by the Mach number and the flow density distributions, are also presented for the condition of maximum cruise.
Testing a new model of ram-air parachute inflation
Authors: Potvin J. 
Published: February 2023

AbstractThis paper reports on the experimental validation of a new model of slider-reefed ram-air parachute opening, using jump data collected by this investigator and others. The model is based on the parachute load equation of motion coupled with a new differential equation which describes the rate of change of the parachute's drag area. The model clearly identifies the important factors which determine the inflation peak load and opening time. It also features many scaling relationships useful for design work. Several predictions are shown to be design-independent. The experimental data used in this model validation were gathered during sport parachuting jumps performed by this author. Also used are data generated by the US Navy during tests of the MC-5, MT-1X/SL and MT-1XX parachutes. The experimental results and model predictions are found to agree within 20% accuracy over a wide range of opening speeds and deployment altitudes.
Large excrescences on transport aircraft: a cautionary tale
Authors: Greenwell D. I. 
Published: February 2023

In recent years the increasing importance of electronic warfare has resulted in a proliferation of assorted antennae, large fairings and other foreign bodies attached to transport aircraft airframes. In many cases the size, shape and location of these excrescences are fixed by the requirements of the relevant electronic devices and it is then left to the engineers and aerodynamicists to attach them to the airframe in the least adverse manner.This note describes an installation which was extensively tested in a large-scale commercial windtunnel and was found to give apparently well-behaved steady-state aerodynamic characteristics but which, when flight tested, exhibited unacceptable levels of airframe buffeting and rather unusual directional stability problems. A re-examination of the fuselage flowfield using a simplified model, but with attention focused on the unsteady aspects of the flow, rapidly identified the underlying cause and enabled a successful aerodynamic fix to be developed. The lessons learnt from this experience are presented as a warning to those contemplating the addition of large excrescences to any airframe.
V-22 Osprey aerodynamic development — a progress review
Authors: McVeigh M. A. , Liu J. , O'Toole S. J. , Woods S. 
Published: February 2023

AbstractEvents in the aerodynamic development of the multi-service V-22 Osprey tiltrotor are reviewed, with emphasis on recent flight test findings and the solutions developed. A discussion of the performance in the USMC, Navy and SOCOM missions is presented.
Neural network models of human operator performance
Authors: May A. 
Published: February 2023

AbstractThis paper examines the feasibility of using neural networks to represent the effects of human operators in computer models of complex man-machine systems. In the suggested approach, data from man-in-the-loop simulators are used to train the networks. The method has been tested on several typical data sets using a stand-alone prototype system, consisting of a three-layer feed-forward network with a Chemotaxis training algorithm. Successful results have been obtained, and these can be used to place constraints on the quality, quantity and type of simulator data required in future applications.
NH90 — the new all military services helicopter
Authors: Geissinger O. W. , Traldi S. L. 
Published: February 2023

The NH90 project formally started in September 1992 when France, Germany, Italy and The Netherlands agreed a contract with NH Industries on the design, development and qualification of an 8-9 tonne class helicopter which shall replace the present fleet of light transport and naval helicopters in the various military services of these states.The NH90 comprises two versions that are based on a weapon system development specification for a Tactical Transport Helicopter (TTH) and a Nato Frigate Helicopter (NFH). The design of the NH90 follows the principle of having as many common basic systems and subsystems as possible in both versions, and to utilise a high level of avionics system integration to provide the capabilities to carry out the required tactical missions with a minimum of crew and crew workload.Consequently, structure, dynamics, general vehicle, and flight control systems, core avionics, and mission equipment are principally common features for both weapon systems. The integration of two specific mission systems, on the other hand, provides the capabilities to employ both versions with a high rate of efficiency in their individual roles. The TTH tactical transport for air forces and armies, and the NFH as a ship embarked anti-submarine/anti-surface unit warfare (ASW/ASUW) for navies, both with the potential for a variety of other missions. The various subsystems of both mission systems, use modern equipment for acquisition of mission relevant information and data, their processing, transformation and display and provide automatic actions or advise to initiate adequate crew reactions.
Validation of a blade-element helicopter model for large-amplitude manoeuvres
Authors: Houston S. S. 
Published: February 2023

AbstractThe contemporary approach to helicopter mathematical modelling in simulation for handling qualities applications is to represent each blade individually. This allows incorporation of effects not possible with a multiblade disc representation of the rotor system. This paper addresses the validation of such a model, which is uniquely performed for large amplitude manoeuvres, using a recently-developed approach to inverse simulation. The method is reviewed in the context of model validation, and comparisons between simulation and actual data are presented for a Puma helicopter executing sidestep manoeuvres in low-speed flight. The focus for interpreting the results is in the area of wake modelling. It is concluded that further developments are necessary in this area if helicopter flight mechanics models are to be used in simulation of role-related flight.
Development of unstructured dynamic grids for solving unsteady two-dimensional Euler equations
Authors: Kozic M. S. , Sredojevic D. 
Published: February 2023

AbstractA method for the solution of the time dependent Euler equations on unstructured grids is presented for unsteady flows about oscillating aerofoils. The flow solver involves a finite volume spatial discretisation and a Runge-Kutta time-stepping scheme. A dynamic mesh algorithm is used for problems where the aerofoil moves and/or deforms. Steady and unsteady results are obtained for single and multi-element aerofoils.