Local Lifting Research Articles

Global liftings between inner forms of GSp(4)

For reductive groups G over a number field we discuss automorphic liftings of cohomological cuspidal irreducible automorphic representations π of G(A) to irreducible cohomological automorphic representations of H(A) for the quasi-split inner form H of G, and other inner forms as well. We show the existence of nontrivial weak global cohomological liftings in many cases, in particular for the case where G is anisotropic at the archimedean places. A priori, for these weak liftings we do not give a description of the precise nature of the corresponding local liftings at the ramified places, nor do we characterize the image of the lifting. For inner forms of the group H=GSp(4) however we address these finer questions. Especially, we prove the recent conjectures of Ibukiyama and Kitayama on paramodular newforms of square-free level.

Rapid dynamic aeroelastic response analysis of the highly flexible wing with distributed propellers influence

Abstract A rapid nonlinear aeroelastic framework for the analysis of the highly flexible wing with distributed propellers is presented, validated and applied to investigate the propeller effects on the wing dynamic response and aeroelastic stability. In the framework, nonlinear beam elements based on the co-rotational method are applied for the large-deformation wing structure, and an efficient cylinder coordinate generation method is proposed for attached propellers at different position. By taking advantage of the relatively slow dynamics of the high-aspect-ratio wing, propeller wake is modeled as a quasi-steady skewed vortex cylinder with no updating process to reduce the high computational cost. Axial and tangential induced velocities are derived and included in the unsteady vortex lattice method. For the numerical cases explored, results indicate that large deformation causes thrust to produce wing negative torsion which limits the displacement oscillation, and slipstream mainly increases the response values. In addition, an improvement of flutter boundary is found with the increase of propeller thrust while slipstream brings a destabilising effect as a result of the increment of dynamic pressure and local lift. The great potential of distributed propellers in gust alleviation and flutter suppression of such aircraft is pointed out and the method as well as conclusions in this paper can provide further guidance.

Numerical model of interaction of a mobile lift chain with a main gas pipeline pipe in the process of repair work

The paper proposes an original design of a mobile lifting device for diagnosing and repairing support nodes of above-ground segments of gas pipelines without stopping gas transportation. When using such a device, the rollers of the lifting chain interact with the surface of the pipe, which can possibly cause additional stresses in the gas pipeline. At the first stage of studying this problem, a model of a typical gas pipeline overhead crossing for the Carpathian region was built and the maximum operating force that should be developed by the mobile lift during repair operations was determined. At the second stage, a finite-element model of the interaction of the mobile lift chain with the main gas pipeline pipe was built. The additional equivalent stresses arising from the contact of the rollers of the lifting chain with the pipe surface were estimated. Recommendations are given to ensure the safe operation of the gas pipeline when using a mobile lift for local lifting of the pipe above the support of above-ground segments of gas pipelines.

Numerical simulation of windsurfing sail aerodynamics: Insights into forces and flow characteristics

In windsurfing, the sail is the primary source of propulsive force. Due to the unique shape and structure, the aerodynamic performance of a windsurfing sail is not well understood. This study aims to investigate the aerodynamic performance of a windsurfing sail under various angles of attack and sail heights using steady Reynolds-averaged Navier–Stokes simulations. The simulations were validated with wind tunnel measurements. The study finds that the local maximum lift coefficient and stall angle are different at different sections along the sail height. Further investigations on the pressure distributions and sectional flow fields indicate that the different sectional lift coefficients and stall are significantly influenced by the geometric profiles and orientations of the luff pocket. The sectional geometric profile consists of a reduced camber near the sail tip, which is prone to flow separation. Thus, flow separation first occurred at the sail tip with increasing angle of attack, then extended towards the sail foot. During flow separation, a recirculation region was found on the suction side of the sail, leading to a reduction in lift and increase in drag. The findings of this study provide insights into the aerodynamic forces and flow characteristics of windsurfing sails, which can be applied to improve sail design and performance.

Quantitative analysis of the Martian atmospheric dust cycle: Transported mass, surface dust lifting and sedimentation rates

The atmospheric dust cycle on Mars plays a dominant role in the planetary radiative balance, atmospheric photochemistry escape, and redistribution of materials on the surface. Although this planetary dust cycle has been extensively modelled and characterized with both orbital and in situ observations, to date little is known about the total mass of dust that is circulated, the actual dust lifting and settling rates, and the main dust sources and sinks. Using orbital global and seasonal measurements of atmospheric dust opacity, a data reduction methodology that can describe the annual dust redistribution cycle on a planetary scale with 95% accuracy is presented. The method was applied to the 9.3 μm infrared observations of the Thermal Emission Spectrometer (TES) aboard the Mars Global Surveyor (MGS) during two full Martian Years (MY) 25 and 26, and partly MY 24 and MY 27, disregarding the global dust storm that occurred in MY 25. By comparison with terrestrial observations, a mass-to-extinction conversion factor of 1.9 ± 0.3 g m−2 is proposed, assuming a dust density of 2.6 g cm−3. The analysis shows an estimation of 400 1012 g of dust transported globally in the atmosphere for a typical Mars year, which is comparable to the minimum total annual mass of dust transported on Earth. The methodology proposed here is based on remote sensing and cannot disentangle completely local surface lifting and sedimentation rates from dust advection. However, this analysis provides upper bounds which can be compared with in-situ observations. The analysis of the dust sedimentation cycle suggests that the annual cycle might produce a dust layer of about 50–100 μm on the surface of some particular zones, as Valle Marineris or Meridiani Planum. This estimation agrees with in-situ observations of rovers on Mars. The potential dust sources are mainly located from latitudes of 20°S to 60°S. Our results find the 70% of the sources previously identified by the existing planetary circulation models. This kind of large-scale analysis can be applied to other remote sensing observations to refine these calculations and study the annual and geographical variability of the dust-mass transport on Mars.

A generalized finite difference method for solving elliptic interface problems with non-homogeneous jump conditions on surfaces

A meshless generalized finite difference method is presented to solve elliptic interface problems with non-homogeneous jump conditions on surfaces. The innovation is that based on a splitting treatment of the interface problem, the generalized finite difference method combined with the local tangential lifting approach is developed for the second-order spatial discretization with low complexity and small stencil. The generalized finite difference method considered is based on Taylor expansion and weighted moving least squares approximation. Under the local tangential lifting framework, the numerical scheme formed by the generalized finite difference method on the tangent plane is regarded as that for the original surface problem. The biggest advantage for combining two methods is that the local tangential lifting framework can reduce the complexity of the discrete process of generalized finite difference method on the surface and resulting relatively small stencil. Several numerical examples are presented to validate the convergence of the proposed method. Numerical results suggest that the proposed approach is effective to the surface interface problem with non-homogeneous jump conditions.

Investigation of the Aerodynamic Forces on a 600-m-High Supertall Building by Field Measurements and Wind Tunnel Test

This paper investigates the aerodynamic forces on a 600-m-high supertall building based on field measurements during Super Typhoon Mangkhut and wind tunnel test on a 1∶500 scaled model of the monitored building. The local wind force coefficients and their power spectral densities obtained by the full-scale measurements and the model experiment are compared and discussed. The comparative study shows that the wind tunnel test provides conservative mean local drag coefficients and root-mean-square (RMS) local lift coefficients, whereas for the RMS local drag coefficients, the model experiment reproduces smaller predictions at higher levels than those from the onsite measurements. Moreover, to explore the deviations between the full-scale and model-scale results, the Reynolds number effects in the range of 5.5×104 to 1.8×108 on the local wind forces and the Strouhal number are investigated. It is found that the Reynolds number has evident effects on the local wind force coefficients, although its influence on the Strouhal number is negligible. This combined study of field measurements and wind tunnel test aims to enhance the understanding of the aerodynamic forces on high-rise buildings during strong windstorms and provide useful information for the wind-resistant design of supertall buildings.

Extended Superolateral Cheek Lift With a Short Preauricular Scar: A Local Anesthesia-based Practicable Technique for the Correction of Moderate-degree Facial Aging Signs.

An ideal technique applicable to middle-aged individuals with a moderate degree of facial aging signs has not yet been established. This study aimed to evaluate the utility of an extended superolateral cheek lift with a short preauricular scar technique for the correction of facial aging signs. A total of 200 female patients (mean age: 43y, range 27-56y) who underwent a local anesthesia-based extended superolateral cheek lift for the correction of facial aging signs confined to the malar and nasolabial area, lower eyelid, jawline, and neck were included. Data on the Global Aesthetic Improvement Scale, patient-reported outcomes, and complications were recorded at 1, 6, 12, and 24 months postoperatively. The Global Aesthetic Improvement Scale scores revealed exceptional improvement in 90% of patients along with no complications at month 24. None of the patients developed a depressed scar, skin necrosis, breaking of the superficial musculoaponeurotic system plication sutures, asymmetry, or facial nerve problems. At postoperative month 24, the appearance was reported to be very much improved by 90% of patients, and 94% of patients reported that they were very satisfied with the treatment and that they would recommend this treatment to friends and acquaintances. Our findings revealed the potential utility of an extended superolateral cheek lift with a short preauricular scar as a local anesthesia-based practicable technique for the correction of facial aging signs in middle-aged patients, offering a favorable postoperative outcome, lack of complications and high patient satisfaction in addition to invisible scars and a short-term postoperative recovery.

Actuator Disk Model with Improved Tip Loss Correction for Hover and Forward Flight Rotor Analysis

A novel actuator disk model (ADM) coupled with lifting-line theory is proposed in this paper. Several virtual planform blades are placed on a disk plane with a constant azimuthal interval, and the lifting-line theory is applied to each blade to predict the effective angle of attack. The proposed model considers the local lift and drag forces acting on disk surface cells by interpolating the predicted effective angle of attack with various azimuth angles to the actuator disk plane; therefore, the proposed model considers individual blade tip vortices without tip loss functions. Experimental data for hover and forward flight rotors are used to validate the proposed model. For hovering flight, sectional thrust based on collective pitch angles predicted by the modified ADM was similar to that obtained in the experiments. For forward flight, the inflow above the rotor estimated by the proposed ADM was similar to that obtained in the experiments and by using other numerical methods. Thus, the developed ADM can be used for rotor performance analysis under the main flight conditions of V/STOL.

Efficient color code decoders in d≥2 dimensions from toric code decoders

We introduce an efficient decoder of the color code in d≥2 dimensions, the Restriction Decoder, which uses any d-dimensional toric code decoder combined with a local lifting procedure to find a recovery operation. We prove that the Restriction Decoder successfully corrects errors in the color code if and only if the corresponding toric code decoding succeeds. We also numerically estimate the Restriction Decoder threshold for the color code in two and three dimensions against the bit-flip and phase-flip noise with perfect syndrome extraction. We report that the 2D color code threshold p2D≈10.2% on the square-octagon lattice is on a par with the toric code threshold on the square lattice.

Outlook on Mozambique’s Agribusiness as a Driving Force for Family Farmers

Family farming is the predominant mode of agricultural production in the world and in Mozambique, producing food, preserving traditional food systems, contributing to a balanced diet, and safeguarding the world’s agro-biodiversity. Micro and family farms have the potential to deal with the complex set of challenges faced in the region, if they are provided with the necessary support, such as agri-technology assistance, infrastructures, and organizational development, to boost local economies and lift communities out of poverty. The present review aimed at showing whether, and to what extent, services of entrepreneurial value could be provided by agrarian incubators to nurture small farmers, namely youngsters and women, to meet market requirements and make a living in the agriculture sector. The focus was on the clarification of the question to what extent smallholder farmers are currently educated at professional schools on how to become successfully self-employed. The answer to this question is needed to outline the current mismatch between vocational agriculture education of farmers and actual market requirements. It was evident that farmers are not educated to successfully meet market requirements and that agriculture incubators considering investment in agribusiness, could be a promising alternative or useful addition for farmers’ vocational preparation. Incubators provides suitable plans for market technologies with agritech start-ups delivering state-of-the-art means to motivate local adaptation, and use, of sustainable practices. There is the need to investigate how to maintain and improve family farmers’ organizations, creating vibrant and inclusive rural societies, while increasing agricultural output with product quality and safety.

Hydrodynamic independence and passive control application of twist and flapwise deformations of tidal turbine blades

The load-induced deformations experienced by axial-flow rotor blades can result in significant hydrodynamic impacts on rotor operation. These changes in hydrodynamics are dominated by the flapwise and twist deformation components, affecting blade loading and performance. This work uses blade-resolved computational fluid dynamics simulations to explore the hydrodynamic interactions of coupled flapwise and twist deformations, and their potential for use in passive control strategies. The rotor blades were simulated under parametrically prescribed flapwise-only, twist-only and coupled flapwise–twist deformations. The results show that the hydrodynamic effects are adequately described by blade-element theory for twist deformations regardless of the presence of flapwise deformations, whereas flapwise deformations induce changes in the local lift and drag coefficients that are independent of twist. For moderate blade deflections, the hydrodynamic changes generated by the two deformation components can be approximated to be independent from each other. The observed hydrodynamic independence between the two deformation components is used to explore passive deformation strategies for a tidal rotor. By extrapolating an existing dataset containing CFD simulations of twist-only and flapwise-only deformation cases at different tip-speed ratios, control paths are designed within a tip-speed ratio, flapwise and twist deformation parameter space. These control paths demonstrate passive control strategies as a potential alternative to active pitch control on tidal turbines, showing similar performance and maximum loading, compared with an active pitch strategy, over a full tidal cycle. In particular, it is shown that flapwise deformations have an important role in power capping above rated flow speed.

New Actuator Disk Model for the Analysis of Wind Turbines Wake Interaction with the Ground

Wake models based on Actuator Disk theory are usually applied to optimize the wind farm layouts and improve their overall efficiency and expected AEP. Despite the effectiveness of the existing models, most Actuator Disk approaches are based on the flow axisymmetric assumption, without considering the ground effect on the wake behavior. However, it has been shown that the mast’s height, or distance from the wind turbine to the ground, has an influence on the wake expansion on both hub’s side and at downstream of the wind turbine. Therefore, in this study, a hybrid CFD-BEM-Actuator Disk approach is developed to address the lack of the existing models. In the proposed model, the 3D wind rotor is modeled by a set of blade elements. Then, the local lift and drag forces acting on each blade element are calculated using BEM theory and incorporated into the momentum equation. This BEM-AD model is implemented in a User Defined Function (UDF) that is loaded into the CFD software. Thereby, ground effects are considered to be a wall boundary and defining a wind boundary layer profile at the inlet boundary, which describes the Atmospheric Boundary Layer (ABL). For the validation of this new Actuator Disk model, an enhanced experimental study is conducted at the Dynfluid Laboratory wind tunnel (ENSAM School Paris Tech). The Particle Image Velocimetry (PIV) measurements are used for the experimental wake explorations applied to a miniature two-bladed wind turbine. The wake developments are analyzed at two different hub heights ratio, h/D = 0.7 and 1.0 (where h is the hub height, and D is the wind rotor diameter). The analysis of the outcomes showed that the numerical simulations are in good correlation with the experimental measurements of the ENSAM wind tunnel. The numerical results show that for h/D=0.7, the upper half of the rotor operates within the boundary layer whereas the lower tip vortices are mainly developed in the horizontal direction with lower intensity compared to the upper tip vortices. This effect was not observed for the case h/D=1.0 where the rotor operates outside of the boundary layer; however, the wake centerline is upward deflected at about 0.3D. The main conclusion is that a distance above 7D must be observed between wind turbines to optimize the wind farm performance and over 1D hub height be required to limit the influence of the ground boundary layer effect.

Analysis of Thrust & Torque B-Series Propeller using CFD: Variation of Blade and nProp

T he propeller is an important part of determining the ship's maneuverability. The propeller itself is a tool to produce thrust that comes from engine power which is transmitted through the shaft . At their defined radial position, Propeller thrust (N) and torque (Nm) are formed from propeller blade foil sections at the local lift and drag. Particularly, the total propeller thrust will be integrated into an axial lift vector for the sections from root to tip . The selection of a good propulsion device will affect the force of the ship. One way to choose the propulsion of the ship is the selection the type of propeller and the provision of new propeller variations to produce maximum thrust. For that reason, this study aims to analyze of thrust and torque of B-series propellers using CFD by varying the number of blades: 3, 4, and 5 blades; and the propeller speed (nProp) i.e., 325, 525, and 725 rpm. The numerical analysis using computational fluid dynamics (CFD) was conducted to identify the thrust (N) and force (Nm) of the propeller. The CFD simulation consists of three main steps: pre-processor, solver manager, and post-processor. The results show that the thrust and torque significantly increased at the higher number of blades and nProp.

Design of Soft-Sensing Model for Alumina Concentration Based on Improved Deep Belief Network

Alumina concentration is an important parameter in the production process of aluminum electrolysis. Due to the complex production environment in the industrial field and the complex physical and chemical reactions in the aluminum reduction cell, nowadays it is still unable to carry out online measurement and real-time monitoring. For solving this problem, a soft-sensing model of alumina concentration based on a deep belief network (DBN) is proposed. However, the soft-sensing model may have some limitations for different cells and different periodic working conditions such as local anode effect, pole changing, and bus lifting in the same cell. The empirical mode decomposition (EMD) and particle swarm optimization (PSO) with the DBN are combined, and an EMD–PSO–DBN method that can denoize and optimize the model structure is proposed. The simulation results show that the improved soft-sensing model improves the accuracy and universality of prediction.

Morphing wing design using integrated and distributed trailing edge morphing

The presented study investigates the design and development of an autonomous morphing wing concept developed in the scope of the SmartX project, which aims to demonstrate in-flight performance optimisation with active morphing. To progress this goal, a novel distributed morphing concept with six translation induced camber morphing trailing edge modules is proposed in this study. The modules are interconnected using elastomeric skin segments to allow seamless variation of local lift distribution along the wingspan. A fluid-structure interaction optimisation tool is developed to produce an optimised laminate design considering the ply orientation, laminate thickness, laminate properties and actuation loads of the module. Analysis of the kinematic model of the integrated actuator system is performed, and a design is achieved, which meets the required continuous load and fulfils both static and dynamic requirements in terms of bandwidth and peak actuator torque with conventional actuators. The morphing design is validated using digital image correlation measurements of the morphing modules. Characterisation of mechanical losses in the actuator mechanism is performed. Out-of-plane deformations in the bottom skin and added stiffness of the elastomer are identified as the impacting factors of the reduced tip deflection.

Computational Fluid Dynamics and Experimental Analysis of a Wind Turbine Blade’s Frontal Section with and without Arrays of Dimpled Structures

Horizontal axis wind turbines are used for energy generation at domestic as well as industrial levels. In the wind turbines, a reduction in drag force and an increase in lift force are desired to increase the energy efficiency. In this research work, computational fluid dynamics (CFD) analysis has been performed on a turbine blade’s frontal section with an NACA S814 profile. The drag force has been reduced by introducing an array of dimpled structures at the blade surface. The dimpled structures generate a turbulent boundary layer flow on its surface that reduces the drag force and modifies the lift force because it has greater momentum than the laminar flow. The simulation results are verified by the experimental results performed in a wind tunnel and are in close harmony with the simulated results. For accurate results, CFD is performed on the blade’s frontal section at the angle of attack (AOA) with a domain of 0° to 80° and at multiple Reynolds numbers. The local attributes, lift force, drag force and pressure coefficient are numerically computed by using the three models on Ansys fluent: the Spalart-Allmaras, the k-epsilon (RNG) and the k-omega shear stress transport (SST).

Unit lifting morphisms

In this paper, we introduce the concept of a unit lifting morphism, a natural generalization of the classical notion “local morphism”, by providing several examples and investigating all its properties and interrelations with local morphisms and unit lifting ideals. Moreover, we expose a relation between a unit lifting morphism f:R→S of rings and the pair (ker(f),f−1(U(S))) and show that unit lifting morphisms correspond to the least element of a partially ordered set. As a prominent result, we provide the equivalent conditions on the existence of a unit lifting morphism from a ring R into a semisimple artinian ring which is intimately related to a deep result by Camps and Dicks that characterizes semilocal rings in terms of local morphisms. This result gives rise to the study of a new class of rings, which we call weakly semilocal rings.

Local tangential lifting virtual element method for the diffusion–reaction equation on the non-flat Voronoi discretized surface

Local tangential lifting virtual element method for the diffusion–reaction equation on the non-flat Voronoi discretized surface

Psychosocial effects of COVID-19 pandemic on dental patients

Introduction: The spread of coronavirus infection (COVID-19) has been increasing exponentially with significant impact on every aspect of people's lives. Dentists in particular are at a greater risk of disease contraction since majority of the procedures are based on direct contact with patients. Aim: This study attempted to understand the attitude of patients seeking dental treatment during the pandemic. Materials and Methods: This was a cross-sectional, self-administered survey which included validated questions on (1) sociodemographic information of participants; (2) participants' basic knowledge on COVID-19; and (3) the willingness and mindset of participants to pursuit dental treatment during, and after the curfew period. Data were collected and statistically analyzed for significance. Results and Discussion: A total of 904 residents from 25 countries. Participants who, or their family members, experienced dental complaints during the curfew period were able to manage via in-office emergency visit, using over counter medication, tele-dentistry or following friends' advice. In total, 48% (433/904) stated to likely seek dental treatment (if needed) with local curfew lifting and 50.4% (456/904) were likely to wait for more than 4 weeks before visiting the dentist. In total, 70% of participants reported sufficient social distancing and wearing masks by the dental staff would address their concerns during dental treatments. Conclusion: Personal financial conditions, lack of awareness, and fear of contracting COVI-19 were identified as important influencing factors for the general public to return for professional dental care. Future, long-term studies to better understand the psychosocial effects of the current pandemic on individuals should be considered.