Lifting Model Research Articles

An accelerometer balance for the measurement of roll, lift and drag on a lifting model in a shock tunnel

A force balance to measure roll, lift and drag on a lifting aerodynamic body in an ultrashort-duration hypersonic test facility, such as a shock tunnel, has been developed and tested on a flapped, blunt-nosed, triangular lifting body at a freestream Mach number of 8. The flow total enthalpy and the freestream unit Reynolds number were 0.83 MJ kg−1 and 0.98 million, respectively. The balance structure has a soft suspension that allows the model to have a free flight during the short-duration aerodynamic test. The balance was mounted inside the hollow model and was equipped with accelerometers to sense the aerodynamic moment and forces on the model. The measurements were carried out at different angles of incidence of the model and the acquired signals of the accelerometers were reduced to the aerodynamic moment and the force coefficients based on the theories of applied mechanics and aerodynamics. Also, the moment and force coefficients were theoretically calculated based on the Newtonian theory, which is an accepted analytical approach for hypersonic bodies. Good agreement has been observed between the experimental and the analytical results. The method of measurement of roll and lift, and the data on the rolling moment of a lifting body presented in this note are novel.

Metabolic constraints on the evolution of genetic codes: Did multiple 'preaerobic' ecosystem transitions entrain richer dialects via Serial Endosymbiosis?

AbstractA spontaneous symmetry lifting model based on Tlusty's elegant topological deconstruction suggests that multiple punctuated ecosystem resilience regime changes in metabolic free energy that were broadly similar to the aerobic transition enabled a punctuated sequence of increasingly complex genetic codes and protein translators. In a manner similar to the Serial Endosymbiosis effecting the Eukaryotic transition, codes and translators coevolved until the ancestor of the present narrow spectrum of protein machineries became locked-in by evolutionary path dependence at a relatively modest level of fitness reflecting a modest embedding metabolic free energy ecology. The simplest coevolutionary model of code-translator interaction has high and low fidelity quasi-equilibria consistent with the 'virus world' hypothesis of Koonin et al. (2006). A more detailed search for empirical evidence of 'preaerobic' ecosystem shifts in metabolic free energy availability or efficiency of use might be surprisingly fruitful.

A robust blade element momentum theory model for tidal stream turbines including tip and hub loss corrections

Blade Element Momentum Theory (BEMT) performance models for wind turbines lead to a robust BEMT model of marine current or tidal stream turbines. It is shown that numerical convergence methods for models reported in the literature are problematic when away from the normal operating range and this paper reports a robust numerical scheme using combined Monte Carlo and sequential quadratic optimisation. The model is extended by Prandtl corrections for losses at the blade tip and hub. Results are validated against an industrial code, Garrad Hassan’s Tidal Bladed Software (GH Tidal Bladed) evaluation version, and a lifting line theory model.

Short-term load forecasting using lifting scheme and ARIMA models

Short-term load forecasting is achieved using a lifting scheme and autoregressive integrated moving average (ARIMA) models. The lifting scheme is a general and flexible approach for constructing bi-orthogonal wavelets that are usually in the spatial domain. The lifting scheme is embedded into the ARIMA models to enhance forecasting accuracy. Based on wavelet multi-revolution analysis (MRA) results, the lifting scheme decomposes the original load series into different sub-series at different revolution levels, which display the different frequency characteristic of a load. The sub-series are then forecast using properly fitted ARIMA models. Finally, forecasting results at different levels are reconstructed to generate an original load prediction by the inverse lifting scheme. In this study, the Coeflet 12 wavelet is factored into lifting scheme steps. The proposed algorithm was tested by applying it to different practical load data types from the Taipower Company in 2007 for one-day-ahead load forecasting. Simulation results indicate that the forecasting performance of the proposed approach is superior to that of the back-propagation network (BPN) algorithm and traditional ARIMA models.

Metabolic constraints on the evolution of genetic codes: Did multiple 'preaerobic' ecosystem transitions entrain richer dialects via Serial Endosymbiosis?

AbstractA spontaneous symmetry lifting model based on Tlusty's elegant topological deconstruction suggests that multiple punctuated ecosystem resilience regime changes in metabolic free energy that were broadly similar to the aerobic transition enabled a punctuated sequence of increasingly complex genetic codes and protein translators. In a manner similar to the Serial Endosymbiosis effecting the Eukaryotic transition, codes and translators coevolved until the ancestor of the present narrow spectrum of protein machineries became locked-in by evolutionary path dependence at a relatively modest level of fitness reflecting a modest embedding metabolic free energy ecology. The simplest coevolutionary model of code-translator interaction has high and low fidelity quasi-equilibria consistent with the 'virus world' hypothesis of Koonin et al. (2006). A more detailed search for empirical evidence of 'preaerobic' ecosystem shifts in metabolic free energy availability or efficiency of use might be surprisingly fruitful.

Torsional Deformation and Fatigue Properties of TiNi SMA Thin Strip For Rotary Driving Element

In order to develop the rotary driving element with SMA thin strip, the torsional deformation and fatigue properties of a TiNi SMA thin strip were investigated. The results obtained are summarized as follows. (1) In the SMA thin strip subjected to torsion, the MT appears along the edge of the strip due to elongation of the edge of the strip and grows to the central part. (2) The number of cycles to failure decreases with an increase in the maximum angle of twist in torsion fatigue. The fatigue life in pulsating torsion is longer than that in alternating torsion by five times. The fatigue limit exists in a certain value of disspated work of the strip in each cycle. (3) Based on the two-way motion of a lifting model by using two kinds of SMA thin strip, it is confirmed that the two-way driving element with a small and simple mechanism can be developed by using the SMA thin strips.

Theoretical and experimental study on seismic response control on top of Three-Gorges ship lift towers using magnetorheological intelligent isolation system and its key technique

A vertical ship lift under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the ship lift towers. This paper proposes a roof magnetorheological (MR) intelligent isolation system to prevent the seismic whipping effect on machinery structures. Theoretically, the dynamic models of MR damper and the mechanical model of ship lift was established, the inverse neural network controlling algorithm was proposed and the fundamental semi-active control equation for the Three-Gorges ship lift where the MR intelligent isolation system was installed was deduced. Experimentally, the experimental model of the ship lift was given, the vibrating table experiment of the MR intelligent isolation system controlling the whipping effect was carried out and the results of the inverse neural network control strategy and passive isolation strategy were compared. In practical aspect, the large-scale MR damper (500 kN) and a sliding support with limited stiffness were designed and fabricated. It was proven that the MR intelligent isolation system with proper control strategy can greatly reduce the seismic whipping effect on the top workshop of the ship lift and be simple and effective enough to be applied to real engineering structures.

The Inverse Vortex Wake Model: A Measurement Analysis Tool

To reduce the level of uncertainty associated with current rotor aerodynamics codes, improved understanding of rotor aerodynamics is required. Wind tunnel measurements on model rotors contribute to advancing our knowledge on rotor aerodynamics. The combined recording of blade loads and rotor wake is desired, because of the coupled blade and wake aerodynamics. In general, however, the small size of model rotors prohibits detailed blade load measurements; only the rotor wake is recorded. To estimate the experimental blade flow conditions, a measurement analysis tool is developed: the inverse vortex wake model. The rotor wake is approximated by a lifting line model, using rotor wake measurements to reconstruct the vortex wake. Conservation of circulation, combined with the Biot–Savart law, allows the induced velocity to be expressed in terms of the bound circulation. The unknown bound circulation can be solved for, since the velocity is known from rotor wake measurements. The inverse vortex wake model is subsequently applied to measurements on the near wake of a model rotor subject to both axial and yawed flow conditions, performed at a TUDelft open jet wind tunnel. The inverse vortex wake model estimates the unsteady experimental blade flow conditions and loads that otherwise would have remained obscured.

A near wake model for trailing vorticity compared with the blade element momentum theory

AbstractA near wake model for trailing vorticity originally proposed by Beddoes for high‐resolution helicopter blade vortex interaction computations has been implemented and compared with the usual blade element momentum models used for wind turbine calculations. The model is in principle a lifting line model for the rotating blade, where only a quarter revolution of the wake system behind the blade is taken into account. This simplification of the wake enables a fast computation of the downwash from the trailed vortex system along the blade using the indicial function method and thus makes it realistic to use the model in aeroelastic time simulations. The downwash from the shed vorticity is also computed with a fast indicial function algorithm. In particular the model is investigated for use in calculations of aerodynamic damping for the different mode shapes of an operating wind turbine. Numerical results for the downwash of a wing in straight flow with elliptical circulation are compared with analytical results. Further, the downwash distribution of a 40 m long rotating blade is computed. Aerodynamic damping of the blade in axial harmonic translation and in the first flapwise mode is computed with the near wake model and compared with the results of a standard momentum model including a model for dynamic inflow. Copyright © 2004 John Wiley & Sons, Ltd.

Compression and Shear Loads on Lumbar Spine Motion Segments in Neutral and Flexed Postures

An analysis was performed to estimate compression and shear loads on three motion segments of the lumbosacral spine in neutral and flexed torso postures. 87 lifting tasks were evaluated using a biodynamic lifting model for lifts starting at 0, 22.5 and 45 degrees torso flexion. Results indicated that the compressive loading on the L5-S1 disk in the 22.5 and 45 degree torso flexion conditions were approximately double and triple those observed in the 0 degree condition. Shear reaction forces acted anteriorly in neutral and moderate flexion, but acted posteriorly in full flexion. Load rates were also dramatically affected by posture, with the load rate in the fully flexed posture being seven times greater than in the neutral posture. Analysis of the upper lumbar levels (L1–L2 and L3–L4) suggested significant shear forces; however, shear forces at L5-S1 remained moderate in all conditions. Results of this analysis will be used in a study examining the fatigue failure of lumbar motion segments when subjected to loads experienced at different angles of torso flexion.

The Model of a Voice-Controlled Lift

The paper provides the analysis of the lift model controlled by voice and sensor control panel. The model is constructed by using average powered controller, it has voice recognition, programmable tenninal and logical lift program, which connect them all. The model can be easily reprogrammed in order to have various working regimes and thus is suitable for training students with the broad automation specialization. Due to flexibility and university of the model the prospective improvement of the system is possible by putting into operation registration of calls control ofthe cage load weight, optimization of the cage stopping and speed in a sense of efficiency and power consumption. Presented system could be used in the smart house projects and, especially for disabled people. The modification ofthe well-known DTW (Dynamic Time Warping) algorithm was used. The set of voice commands consisted of eight Lithuanian words (floor number, go, stop) and two phrases (greeting and goodbye). The recognition accuracy of eight voice commands was equal 100%, two commands were recognized with some errors. The voice controlled lift model was demonstrated in the exhibition “Science-2002” in Lithuania

Deaths in construction related to personnel lifts, 1992–1999

Problem: This study examined deaths of construction workers due to personnel lifts (boom-supported and scissor lifts, suspended scaffolds, and crane platforms). Methods: Deaths of construction workers for 1992–1999 were examined using data from the Census of Fatal Occupational Injuries, a Bureau of Labor Statistics database. Results: The study identified 339 deaths: 42% from boom-supported lifts; 26% from suspended scaffolds; 19% from scissor lifts; 5% from crane platforms; and 7% from unapproved lifts (e.g., forklift platforms). The main causes of death were falls (36%), collapses/tipovers (29%), and electrocutions (21%). Discussion: Recommendations include: following OSHA regulations, wearing personal fall protection equipment, adequate maintenance, inspection before use, and training on the model of lift used. Precautions are also needed to prevent contact with overhead power lines. Impact on industry: The increasing popularity of boom-supported lifts and scissor lifts, both in construction and other industries, make their safety an important issue.

Design of a Three Surfaces R/C Aircraft Model

Design of a three lifting surfaces radio-controlled model has been carried out at Dipartimento di Progettazione Aeronautica (DPA) by the authors in the last year. The model is intended to be a UAV prototype and is now under construction. The main goal of this small aircraft's design is to check the influence of the canard surface on the aircraft's aerodynamic characteristics and flight behavior, especially at high angles of attack. The aircraft model is also intended to be a flying platform to test sensors, measurement and acquisition systems for research purposes and a valid and low-cost teaching instrument for flight dynamics and flight maneuvering. The aircraft has been designed to fly with and without canard, and all problems relative to aircraft balance and stability have been carefully analyzed and solved. The innovative configuration and the mixed wooden-composite material structure has been obtained with very simple shapes and all the design is focused on realizing a low-cost model. A complete aerodynamic analysis of the configuration up to high angles of attack and a preliminary aircraft stability and performance prediction will be presented.

An analytical model of the dynamic lift experienced by a bubble moving off-angle to an inviscid flow field with vorticity

As a bubble traverses an inviscid flow field possessing vorticity it experiences a lift force in proportion to the cross-product of the relative velocity difference and the flow field vorticity. The proper derivation of this force construct is important in the formulation of bubble trajectory models applied to high vorticity regions such as a shear flow, but is hampered by three aspects. First, there is disagreement as to the evolutionary basis of the lift force. Second, the models of lift force are derived for a nominal one-dimensional flow case, i.e., collinear bubble velocity and flow field velocity vectors, but are applied to general three-dimensional simulations where the two velocities are not necessarily co-planar. This vectorial generalization of dynamic lift has not been validated. Third, the mathematical model to predict lift force is awkward to apply in a numerical trajectory simulations. In the present study, we argue that the lift force derives from a contouring of the kinetic energy and convective potential-rate fields. This forms the basis for a simple predictive tool which is termed a split lamina model, which is capable of extracting an analytical validation of the vectorial generalization. Conceptually, the split lamina model artificially cleaves a bubble into two separate halves along the plane of the impinging flow field velocity. As each half-bubble resides a flow field of a slightly different velocity, the force acting on respective halves is calculated by integrating the defect in kinetic energy and convective potential-rate. Upon mathematical reassembly of the halves the registered force imbalance is assigned to be the lift force. For a simple shear flow, the split lamina technique predicts the analytical lift coefficients for a sphere to within three percent of the accepted value C L =1/2. Hence, promoting a study of the off-nominal flow conditions, the 3D vectorial generalization of Auton (1987. Journal of Fluid Mechanics, 183, 199–218) is subsequently validated by applying the velocity potential derived in Schrage (1998. Ph.D. thesis, Department of Mechanical and Aerospace Engineering, Case Western Reserve University, May). For moderate three dimensionality, the split lamina model emulates the vectorial generalized lift force to within 10 percent. To simplify the conventional cross-product format, the lift force is compacted as an adjunct force tensor K which operates on the bubble relative velocity difference vector to describe the force in accordance with F L = ρV( a) K ( u − v).

Application of the lifting wavelet to rough surfaces

This paper proposes a lifting wavelet model for enhancement of accuracy of surface roughness characterisation. In this work, the theory and fast algorithm of the lifting wavelet are briefly introduced and a lifting wavelet model for extraction of roughness of surfaces has been developed. The rough surface recovered has good refinement accuracy in contrast to the least squares polynomial fitting. Applications are conducted by using a series of typical surfaces, planes and curves, measured by contact (stylus) and non-contact (phase-shifting interferometry) instruments, to demonstrate the feasibility and applicability of using the lifting wavelet model in the analysis of these surfaces.

Autonomous formation flight

This article describes an approach to close-formation flight of autonomous aircraft. A standard LQ-based structure was synthesized for each vehicle and for formation position error control using linearized equations of motion and a lifting line model of the aircraft wake. We also consider the definition of a formation management structure, capable of dealing with a variety of generic transmission and communication failures among aircraft. The procedure was developed using a decentralized approach and relies on the Dijkstra algorithm. The algorithm provides optimal path information sequencing in the nominal case, as well as the redundancy needed to accommodate failures in data transmission and reception. Several simulations were carried out, and some of the results are presented. The overall scheme appears to be a valuable starting point for further research, especially specialization to situations representing more detailed and operational failures.

Use of human expertise in the evaluation of manual lifting activities

The primary objective of this research is to determine whether or not worker expertise can be used to evaluate industrial lifting activities in order to prevent lower back injuries in the workplace. Twenty-two professionals and twenty-two skilled laborers participated in the study. The results obtained in this study indicate that it may possible to use personal knowledge and experience in evaluating physical tasks such as lifting. Furthermore, there was no difference between professionals and skilled laborers in terms of the cognitive patterns relating input to output variables. This provides preliminary evidence that the logic of experienced workers is as good as that of professionals. In the open lifting model examined in this study, it is clear that the weight of load is perceived by the study participants as the most important variable in evaluating lifting activities and is in agreement with findings in the published literature. In the closed loop model, perceived risk emerges as an important variable in determining the effort level exerted during lifting activities, even more important than the weight of load.

Development of the Quantitative Model for Application of Workers' Expertise in Evaluating Manual Lifting Tasks

The objective of this paper is to investigate how worker expertise can be used to evaluate industrial lifting activities, with the ultimate goal of preventing lower back injuries in the workplace. Twenty-two professionals and twenty-two skilled laborers participated in the study. The results indicate that it is possible to use personal knowledge and experience in evaluating injury risks of physical tasks such as lifting. There was no difference between professionals and skilled laborers in terms of the cognitive patterns relating input to output variables. In the open lifting model, the weight of load was the most important variable in evaluating lifting activities, in agreement with findings in the literature about the association of task variables with back injuries at the time of the accident. In the closed loop model, perceived risk emerges as a primary variable in determining the effort level exerted during lifting activities followed by the weight of load.

The L5/S1 joint moment sensitivity to measurement errors in dynamic 3D multisegment lifting models

The purpose of this study was to compare the sensitivity of two dynamic tridimensional (3D) multisegment lifting models (upward and downward) to different errors. Two types of lifting tasks (sagittal and asymmetric) were considered. Five cameras, two force platforms and a dynamometric box provided inputs to the models. Known errors were induced in (1) joint centres, (2) the orientation of the anatomical coordinate system (ACS) of the pelvis, (3) external forces and (4) their point of application, (5) linear accelerations of segments' centre of mass and (6) body segment parameters (BSP) data to study their effect on the L5/S1 moments of both models. The results revealed that errors in joint centres and in the orientation of ACS axes were the principal sources of variability for both models. The upward model also require precise measurement of the point of application of the external forces while a downward model needs an accurate estimation of the BSP of trunk segments and an adequate estimation of upper segment accelerations. Since combined errors in the three moment components at L5/S1 generated an average of 5–9% incertitude in lumbar compression force estimates, it was concluded that the reduction of moment errors is important in spine modelling. PsycINFO classification: 2220; 2240; 4010

Determination of the effect of lift characteristics on dynamic performance profiles during manual materials handling tasks

In any quantitative gait or occupational biomechanics investigation, the quantification of the different kinematic, kinetic, and electromyographic parameters is essential towards assessment of functional capacity and development of a biomechanical profile of the task demands. In the current study, the authors presented a methodology for using inferential statistics to evaluate the effect of lift characteristics on phase-dependent and phase-independent variability in performance. Using a database of kinematic and kinetic profiles obtained from a manual lifting study, the phase-dependent effects of lift characteristics: box mass (load), mode (technique of lift), and speed (frequency of lift) were investigated through the use of analysis of variance (ANOVA) techniques, which recognize the vectorial constitution of the profiles. In addition, the Karhunen-Loeve Expansion (KLE) feature extraction method was used for representing the lifting patterns of measured joint angular position, velocity, acceleration, and net muscular torque profiles obtained from a 2-D biomechanical lifting model in order to study the phase-independent effects. In comparison to traditional descriptive statistical analyses currently used in various occupational biomechanics experimental investigations, this method allows the significant information content of the time varying signal to be captured, enhancing the sensitivity of subsequent hypothesis testing procedures. The application of this technique to MMH investigations allows identification of the lift characteristics that dominate the variability of task demands, hence aiding in the design and assessment of ergonomic solutions.