Static Lift Research Articles

Modeling effects of membrane tension on dynamic stall for thin membrane wings

An approach for predicting time varying aerodynamic loads on a pitching membrane wing due to rotational pitching and steady airflow is presented. The proposed model utilizes potential flow theory for a thin cambered airfoil with finite span, combined with a linearized representation of the membrane physics to predict lift under static conditions. Quasi-steady rotational effects and added mass effects are considered in a classic potential flow approach, modified for a membrane airfoil. A high-fidelity numerical model has been developed as well, coupling a viscous fluid solver and a non-linear membrane structural model, to predict the configuration of the system under static and unsteady loads. Moving Least Squares are used to map the structural and fluid interface kinematics and loads during the fluid–structure co-simulation. The static and dynamic lift predictions of the two models are compared to wind tunnel data, and show reasonable accuracy over a wide range of flow conditions, reduced frequency, and membrane pretension.

System identification of an airship using trust region reflective least squares algorithm

Lighter than air vehicles present feasible solutions to several problems in aviation industry. Dynamic modeling of airships, however, poses enhanced complexities due to the effects of buoyancy-based static lift and virtual mass and inertia. System identification is an established technique for modeling aerial vehicles, but it generally requires huge amount of flight data, acquired through costly sensors operating at high sampling rates. Earlier airship identification works have used output/filter error methods, evolution strategies and subspace identification methods; all using large sets of estimation data. In this research, the longitudinal dynamics of a 30 ft long unmanned airship have been modeled using very less estimation data. During airship’s flight experiment, flight data was recorded at a minimal sampling frequency of 8 Hz, using low-cost sensors. The less estimation data was compensated by iterative estimation technique, instead of one-step estimation. The flight data was subjected to trust region reflective least squares algorithm that is based on a relatively new and efficient optimization method. The model estimation quality was quantified by residual analysis and Akaike’s criterion of final prediction error. The promising cross-validation results show that the adopted identification approach is suitable and cost-effective for modeling of complex airship dynamics.

Influence of side-shift therapy associated or not with a shoe lift on idiopathic scoliosis

Abstract Introduction: The benefits of side-shift therapy associated with a shoe lift in scoliosis can act by reorganizing the asymmetries found in these individuals. The aim of this study was to analyze the influence of side-shift therapy with or without a high or low shoe lift in patients with idiopathic scoliosis. Materials and Methods: 10 individuals of both genders, aged 13-24 years, were selected, with scoliosis "S" and right thoracic and left lumbar greater than 10º. Initially the order of the task was static and then dynamic, after which there was a draw for the conditions with the shoe lift. The values of postural angles during the five lateral tilt movements were obtained and also the minimum and maximum values of each movement. The average value of postural angle in the static position, without a shoe lift, was used as a reference. Results: The movement associated with the shoe lift demonstrated less significant results compared with the effect of the static shoe lift and the side-shift movements performed in isolation, no significant results in any angle were found. Discussion: Both movements, to the side of the convexity or to the opposite side, seemed to decrease the effect of the shoe lift. The side-shift movement performed in isolation failed to influence the postural angles in general, demonstrating that acute intervention may not be efficient. Conclusion: The influence of side-shift therapy associated with a high or low shoe lift on both sides was effective, but the shoe lift in the static position produced the most significant changes and therefore is considered a better intervention in order to prevent the progression of double curve in patients with idiopathic scoliosis.

Caffeine improves muscular performance in elite Brazilian Jiu-jitsu athletes

Scientific information about the effects of caffeine intake on combat sport performance is scarce and controversial. The aim of this study was to investigate the effectiveness of caffeine to improve Brazilian Jiu-jitsu (BJJ)-specific muscular performance. Fourteen male and elite BJJ athletes (29.2 ± 3.3 years; 71.3 ± 9.1 kg) participated in a randomized double-blind, placebo-controlled and crossover experiment. In two different sessions, BJJ athletes ingested 3 mg kg−1 of caffeine or a placebo. After 60 min, they performed a handgrip maximal force test, a countermovement jump, a maximal static lift test and bench-press tests consisting of one-repetition maximum, power-load, and repetitions to failure. In comparison to the placebo, the ingestion of the caffeine increased: hand grip force in both hands (50.9 ± 2.9 vs. 53.3 ± 3.1 kg; respectively p < .05), countermovement jump height (40.6 ± 2.6 vs. 41.7 ± 3.1 cm; p = .02), and time recorded in the maximal static lift test (54.4 ± 13.4 vs. 59.2 ± 11.9 s; p < .01).The caffeine also increased the one-repetition maximum (90.5 ± 7.7 vs. 93.3 ± 7.5 kg; p = .02), maximal power obtained during the power-load test (750.5 ± 154.7 vs. 826.9 ± 163.7 W; p < .01) and mean power during the bench-press exercise test to failure (280.2 ± 52.5 vs. 312.2 ± 78.3 W; p = .04). In conclusion, the pre-exercise ingestion of 3 mg kg−1 of caffeine increased dynamic and isometric muscular force, power, and endurance strength in elite BJJ athletes. Thus, caffeine might be an effective ergogenic aid to improve physical performance in BJJ.

ILift: A health behavior change support system for lifting and transfer techniques to prevent lower-back injuries in healthcare

ObjectiveLower back problems are a common cause of sick leave of employees in Dutch care homes and hospitals. In the Netherlands over 40% of reported sick leave is due to back problems, mainly caused by carrying out heavy work. The goal of the iLift project was to develop a game for nursing personnel to train them in lifting and transfer techniques. The main focus was not on testing for the effectiveness of the game itself, but rather on the design of the game as an autogenous trigger and its place in a behavioral change support system. In this article, the design and development of such a health behavior change support system is addressed, describing cycles of design and evaluation. Methods(a) To define the problem space, use context and user context, focus group interviews were conducted with Occupational Therapists (n=4), Nurses (n=10) and Caregivers (n=12) and a thematic analysis was performed. We interviewed experts (n=5) on the subject of lifting and transferring techniques. (b) A design science research approach resulted in a playable prototype. An expert panel conducted analysis of video-recorded playing activities. (c) Field experiment: We performed a dynamic analysis in order to investigate the feasibility of the prototype through biometric data from player sessions (n=620) by healthcare professionals (n=37). Results(a) Occupational Therapists, Nurses and Caregivers did not recognise a lack of knowledge with training in lifting and transferring techniques. All groups considered their workload, time pressure and a culturally determined habit to place the patient's well being above their own as the main reason not to apply appropriate lifting and transferring techniques. This led to a shift in focus from a serious game teaching lifting and transferring techniques to a health behavior change support system containing a game with the intention to influence behavior. (b) Building and testing (subcomponents of) the prototype resulted in design choices regarding players perspective, auditory and visual feedback, overall playability and perceived immersiveness. This design process also addressed the behavior shaping capacities of the game and its place within the health behavior change support system. An expert panel on lifting and transferring techniques validated the provoked in-game activities as being authentic. (c) Regression analysis showed an increase of the game score and dashboard score when more sessions were played, indicating an in-game training effect. A post-hoc test revealed that from an average of 10 playing sessions or more, the dashboard score and the game score align, which indicates behavioral change towards executing appropriate static lifting and transferring techniques. ConclusionsData gathered in the final field test shows an in-game training effect, causing players to exhibit correct techniques for static lifting and transferring techniques but also revealed the necessity for future social system development and especially regarding intervention acceptance. Social system factors showed a strong impact on the games persuasive capacities and its autogenous intent.

Human fatigue and the crash of the airship Italia.

The airship Italia, commanded by General Umberto Nobile, crashed during its return flight from the North Pole in 1928. The cause of the accident was never satisfactorily explained. We present evidence that the crash may have been fatigue-related. Nobile’s memoirs indicate that at the time of the crash he had been awake for at least 72 h. Sleep deprivation impairs multiple aspects of cognitive functioning necessary for exploration missions. Just prior to the crash, Nobile made three command errors, all of which are of types associated with inadequate sleep. First, he ordered a release of lift gas when he should have restarted engines (an example of incorrect data synthesis, with deterioration of divergent thinking); second, he inappropriately ordered the ship above the cloud layer (a deficiency in the assessment of relative risks); and third, he remained above the cloud layer for a prolonged period of time (examples of attention to secondary problems, and calculation problems). We argue that as a result of these three errors, which would not be expected from such an experienced commander, there was no longer enough static lift to maintain level flight when the ship went below the cloud layer. Applying Circadian Performance Simulation Software to the sleep–wake patterns described by Nobile in his memoirs, we found that the predicted performance for someone awake as long as he had been is extremely low. This supports the historical evidence that human fatigue contributed to the crash of the Italia.

Musculoskeletal Disorders among Medical Laboratory Professionals-A Prevalence Study

Background: Work –related musculoskeletal disorders (WRMSD) have been reported very often in various occupations. Laboratory personnel are also exposed to many ergonomic risk factors due to the nature of their work. As their work demands awkward and static postures, high repetition, excessive force, excessive reaching, compression or contact stress, forceful or static exertions, lifting and pinch grip lifting, and repetitive motions, they may be at increased risk for work related musculoskeletal disorder which is often ignored. So the study was aimed at estimating the prevalence of work related musculoskeletal disorders among laboratory professionals. Methods: It was a cross sectional study done on 250 laboratory professionals (lab technicians, pathologists, microbiologists, biochemistry technologist) in Udupi district of Karnataka state and validated questionnaire was used to screen for the symptoms. Data were analyzed using descriptive statistics. Results: Prevalence of musculoskeletal symptoms among laboratory professionals was found to be 21.2%. The neck and lower back are observed to be the most affected with symptoms of pain and discomfort with prevalence of 8% and 6.8% respectively. Conclusion: Medical laboratory professionals are at high risk for the development of MSDs related to cumulative trauma. Thus, laboratory professionals are strongly encouraged to adopt preventive measures before symptoms develop.

Relação entre testes de resistência de força com o kimono com parâmetros isocinéticos em atletas de jiu jitsu

The aim of the present study was to correlate two specific kimono grip strength tests (KGST) with elbow flexors and extensors isokinetic parameters in Jiu Jitsu (JJ) athletes. Fifteen male JJ athletes, from blue to black belt, participated in the study. The two KGST were: maximum static lift (MSL), and maximum number of repetitions (MNR), both gripping a kimono wrapped around a bar. Isokinetic tests consisted of three sets of 5 s elbow flexion-extension maximum voluntary isometric contraction (MVIC) in three different elbow angles (45, 90 and 120°), and two sets of five concentric-eccentric elbow flexion-extension maximum dynamic contractions at 60°∙s-1, to determine peak torque (PT). Absolute values of MSL and MNR were 41.4 ± 16.2 s and 10 ± 5 reps, respectively, and tests presented a nearly perfect correlation among them (r=0.91; p<0.001). Significant correlations were reported between MNR and PT during MVIC for elbow flexors at 45° and 90°, elbow extensors at 120°, and during concentric and eccentric dynamic contractions for both flexors and extensors. Therefore, KGST were highly correlated with isokinetic parameters, and were nearly perfect correlated among them, supporting that one of the tests could be chosen to evaluate strength in JJ athletes. The MNR test presented apparently higher levels of relation than MSL, and provided significant information about muscle strength endurance in JJ athletes.

Linear Reduced-Order Model for Unsteady Aerodynamics of an L-Shaped Gurney Flap

The purpose of the work is to investigate the mechanism that underlies the development of unsteady loads by a novel L-shaped Gurney flap conceived to perform vibration control on rotorcraft blades. The device is combination of a spoiler with a Gurney flap. Exploiting the capabilities of a Reynolds-averaged Navier–Stokes flow solver employing the overset mesh approach, several numerical simulations are carried out at low Mach number. These simulations are used to develop a physically based linear reduced-order model in the frequency domain for the unsteady lift and pitching moment of a NACA 0012 airfoil, considering as input the pitch and plunge harmonic oscillations of the airfoil, together with the oscillations of the L-shaped Gurney flap. The aerodynamic assessment of the L-tab shows that the behavior of the loads can be predicted using an equivalent flat-plate model to represent the airfoil composed by three segments: the first representing the fixed part of the airfoil, the second representing the longitudinal edge of the tab, and the third representing the counter-rotating vortical structures that appear behind the movable device. The same approach is used to model the static lift and moment enhancements, as due to an equivalent camber modification effect. The strong connection of the parameters of the reduced-order model with the physical quantities is highlighted as well as its predictive capability for arbitrary parameters of the imposed motion laws.

From AutoCAD to 3ds Max: An automated approach for animating heavy lifting studies

Modular construction is a dominant manufacturing method for industrial construction in Alberta, Canada. Modularization requires large-capacity mobile cranes to lift heavy modules, such as piperack modules. The current practice utilizes AutoCAD to generate heavy lift studies for modular onsite installations. Heavy lift studies consist of 2D and 3D simulations of the lifting scenarios, along with the corresponding calculations (e.g., lifting capacity checking, ground bearing pressure checking). These static simulations provide snapshots of mobile cranes at pick and set configurations, but they do not represent the movements between the two configurations. For better communication among site engineers and crews, current static heavy lift studies need to be improved by animating the entire lifting process. 3ds Max is an animation tool that can visualize the lifting process, but the tedious and manual process of preparing the animation restricts efficiency and productivity. This research thus introduces a newly developed animation system that automates the transfer of heavy lift studies from AutoCAD into Autodesk 3ds Max animation. Also in this research, the kinetics of mobile cranes are studied and generic crane movements are defined. Using MAXScript, a script is written to link the crane and project database for automatic generating of animations. This research aims to provide the construction industry with a generic method for automating the animation process for heavy lifts based on AutoCAD and 3ds Max systems.

Nutritional status and the gonadotrophic response to a polar expedition

Polar expeditions have been associated with changes in the hypothalamic-pituitary-testicular axis consistent with central hypogonadism (i.e., decreased testosterone, luteinising hormone (LH), and follicle stimulating hormone (FSH)). These changes are typically associated with body mass loss. Our aim was to evaluate whether maintenance of body mass during a polar expedition could mitigate against the development of central hypogonadism. Male participants (n = 22) from a 42-day expedition (British Services Antarctic Expedition 2012) volunteered to take part in the study. Body mass, body composition, and strength data were recorded pre- and postexpedition in addition to assessment of serum testosterone, LH, FSH, thyroid hormones, insulin-like growth factor 1 (IGF-1), and trace elements. Energy provision and energy expenditure were assessed at mid- and end-expedition. Daily energy provision was 6335 ± 149 kcal·day(-1). Estimated energy expenditure midexpedition was 5783 ± 1690 kcal·day(-1). Body mass and percentage body fat did not change between pre- and postexpedition. Total testosterone (nmol·L(-1)) (14.0 ± 4.9 vs. 17.3 ± 4.0, p = 0.006), calculated free testosterone (pmol·L(-1)) (288 ± 82 vs. 350 ± 70, p = 0.003), and sex hormone binding globulin (nmol·L(-1)) (33 ± 12 vs. 36 ± 11, p = 0.023) concentrations increased. LH and FSH remained unchanged. Thyroid stimulating hormone (TSH; IU·L(-1)) (2.1 ± 0.8 vs. 4.1 ± 2.1, p < 0.001) and free triiodothyronine (FT3; IU·L(-1)) (5.4 ± 0.4 vs. 6.1 ± 0.8, p < 0.001) increased while free thyroxine, IGF-1, and trace elements remained unchanged. Hand-grip strength was reduced postexpedition but static lift strength was maintained. Maintenance of body mass and nutritional status appeared to negate the central hypogonadism previously reported from polar expeditions. The elevated TSH and free FT3 were consistent with a previously reported "polar T3 syndrome".

Experimental Investigation on the Performance of NACA 4412 Aerofoil with Curved Leading Edge Planform

Aircraft wings are the lifting surfaces with the chosen aerofoil sections. The efficiency as well as the performance of an aircraft mostly depends on the aerodynamic characteristics e.g. lift, drag, lift to drag ratio, etc of wings. Besides many factors, the effects of wing shape are also crucial to aircraft performance. This paper represents the experimental investigation to explore better aerodynamic performance by incorporating curvature at the leading edge of a wing. A wooden model with straight leading and trailing edge i.e. rectangular planform and another model with curved leading edge and straight trailing edge are prepared with NACA 4412 aerofoil in equal length (span) and surface area. Both the models are tested in a closed circuit wind tunnel at air speed of 85.35 kph (0.07 Mach) i.e. at Reynold's number 1.82×105. The static pressure at different angles of attack (-4°, 0°, 4°, 8°, 12°, 16°, 20° & 24°) are measured from both upper and lower surfaces of the wing models through different pressure tapings by using a multi-tube water manometer. From the static pressure distribution, lift coefficient, drag coefficient and lift to drag ratio of both the models are analyzed. After analyzing the data, it is found that the curved leading edge wing planform is having higher lift coefficient and lower drag coefficient than the rectangular wing planform. Thus, the curved leading edge planform is having higher lift to drag ratio than the rectangular planform.

Low Reynolds Number Performance of a Model Scale T-Foil

"Submerged T-foils are an essential forward component of the ride control systems of high speed ferries. A model scale T-Foil for a 2.5m towing tank model of a 112m INCAT Tasmania high-speed wave-piercer catamaran has been tested for both static and dynamic lift performance. The tests were carried out using a closed-circuit water tunnel to investigate the lift and drag characteristics as well as frequency response of the T-Foil. The model T-Foil operates at a Reynolds number of approximately 105, has an aspect ratio of 3.6 and a planform which is strongly tapered from the inboard to outboard end. All of these factors, as well as strut and pivot interference, influence the steady lift curve slope of the model T-foil which was found to be 61% of the value for an ideal aerofoil with elliptic loading. The T-foil dynamic performance was limited primarily by the stepper motor drive system and connection linkage. At the frequency of maximum motion of the 2.5 m catamaran model (about 1.5Hz) the model T-foil has approximately 5% reduction of amplitude and 15 degrees of phase shift relative to the low frequency response. Only very small limitations arose due to the unsteady lift as predicted by the analysis of Theodorsen. It was concluded that the model scale T-foil performed adequately for application to simulation of a ride control system at model scale."

Predictions of Flow Separation at the Valve Seat for Steady-State Port-Flow Simulation

Steady-state port-flow simulations with static valve lift are often utilized to optimize the performance of intake system of an internal combustion engine. Generally, increase in valve lift results in higher mass flow rate through the valve. But in certain cases, mass flow rate can actually decrease with increased valve lift, caused by separation of turbulent flow at the valve seat. Prediction of this phenomenon using computational fluid dynamics (CFD) models is not trivial. It is found that the computational mesh significantly influences the simulation results. A series of steady-state port-flow simulations are carried out using a commercial CFD code. Several mesh topologies are applied for the simulations. The predicted results are compared with available experimental data from flow bench measurements. It is found that the flow separation and reduction in mass flow rate with increased valve lift can be predicted when high mesh density is used in the proximity of the valve seat and the walls of the intake port. Higher mesh density also gives better predictions of mass flow rate compared to the experiments, but only for high valve lifts. For low valve lifts, the error in predicted flow rate is close to 13%.

Effects of surface roughness and cross-sectional distortion on the wind-induced response of bridge cables in dry conditions

Theoretical and experimental investigations to date have assumed that bridge stay cables can be modelled as ideal circular cylinders and that their aerodynamic coefficients are invariant with wind angle-of-attack. On the other hand it has been demonstrated that bridge cables are characterised by local alterations of their inherent surface roughness and shape. Small deviations from ideal circularity result in significant changes in the static drag and lift coefficients with Reynolds number. The present study focuses on the wind-induced response of a full-scale yawed bridge cable section model, for varying Reynolds numbers and wind angles-of-attack. Using passive-dynamic wind tunnel tests, it is shown that the in-plane aerodynamic damping of a bridge cable section, and the overall dynamic response, is strongly affected by changes in the wind angle-of-attack. Using the drag and lift coefficients, determined in static conditions for an identical cable model as the one used for passive-dynamic tests, the in-plane aerodynamic damping is evaluated by employing a one-degree-of-freedom (1 DOF) quasi-steady analytical model. Similarly, it is shown that regions of instability associated with the occurrence of negative aerodynamic damping are strongly dependent on the wind angle-of-attack.

Enhancing Ergonomic Safety Effectiveness of Repetitive Job Activities: Prediction of Muscle Fatigue in Dominant and Nondominant Arms of Industrial Workers

AbstractWork‒related musculoskeletal disorders are very common in the workplace, especially with tasks involving repetitive lifting and motions. Repetitive lifting of excessively heavy objects in the workplace could increase the severity and rates of work‒related musculoskeletal disorders. In this article, the physiological effect of muscle fatigue on the dominant and nondominant arms of adult industrial workers performing various repetitive tasks was predicted using a muscular endurance model. Twenty‒four (n = 24) industrial workers (18–45 years old) were randomly selected for this research. The effects of electromyography (EMG) were observed during incremental loading of 5–40 kg on the muscle of the dominant and nondominant arms of the subjects during static lifting activities. Results of the analysis showed that the endurance time decreased with the application of additional loads on the dominant and nondominant arms of all the subjects. This inverse relationship was used to predict the behavior of muscle fatigue. Additional findings indicated that workers performing repetitive lifting tasks could maintain maximum load capacities ranging from 20 to 30 kg. The acceptable maximum load capacity of 23 kg recommended by the National Institute for Occupational Safety and Health is within this range. The results obtained from this research could be used in the beginning steps of the efforts to reevaluate and reestablish guidelines and limits in the design of industrial jobs involving repetitive motion. © 2014 Wiley Periodicals, Inc.

Comparison of Test Standards for the Performance and Safety of Agricultural Tractors: A Review

Purpose: The objective of this paper was to compare test standards regarding the performance and safety of agricultural tractors to identify the differences in test conditions, measurement tolerances, and test procedures. Based on the comparison, some recommendations were proposed for possible rev isions or improvements to current tractor test standards. Methods: The test standards and codes of major standards development organizations (SDOs), such as the Organization for Economic Co-operation and Development (OECD), the International Organization for Standardization (ISO), the American Society of Agricultural and Biological Engineers (ASABE), EC type approval, and the board of actions of the Nebraska Tractor Test Laboratories (NTTL), were selected and analyzed. Comparison of the test standards: The ISO provides references for fuel and lubricants for tractor tests, and the OECD provides additional measurements for calculating fuel consumption characteristics during the power take-off (PTO) tests. The ISO, EC type approval, and the ASABE provide PTO protective device and the safety requirements. During drawbar power tests, seven transmission ratios are selected for fully automatic transmissions, according to the OECD. In case of hydraulic lift tests, ISO 789-2 and OECD Code 2 advise the use of a static lift force, while SAE J283 advises the use of additional dynamic lift capacity tests for a better representation of in-field operations. The OECD, the ISO, and EC type approval determine the seat index point (SIP), whereas the ASABE determines the seat reference point (SRP) for roll-over protective structure (ROPS) tests. Diversified measurement tolerances were among the braking performance test standards. The European Union (EU) has developed daily limits for vibration exposures with adaptations from ISO 2631-1. Electroma gnetic compatibility evaluations are emerging of high-efficiency tractors due to the long-term conformance to electromagnetic emissions and interferences. Comparisons of tractor test standards discussed in this paper are expected to provide useful information for tractor manufacturers and standards development personnel to improve the performance and safety test standards of tractors.

Effects of work experience and exertion height on static lifting strengths and lift strategies of experienced and novice female participants

In this study, 46 female experienced workers and inexperienced novices (23 each) were recruited to determine their maximum lifting strength at 15 exertion heights between 10 and 150 cm from the floor. The results revealed that the experienced workers' strengths at all 15 heights exhibited relatively little fluctuation, and were approximately 50–70 N lower than those of novices when heights were ≤50 cm. No differences in strengths were observed at 60–150 cm between the groups. The experienced workers tended to adopt a consistently deep squat at lower heights (≤50 cm) and a more erect posture with stiffened arms at higher heights (≥70 cm), resulting in lower L4/L5 disc compression forces and shoulder moments than in novices, respectively. In contrast to the lifting techniques adopted by experienced workers to effectively avoid overloading, the findings suggest that novice female workers who lack experience should be cautious and trained for performing lifting tasks. Relevance to industryThis study demonstrated that a discrepancy exists in lifting strengths between experienced and inexperienced female handlers at various heights. Findings from this study offers a reference for lifting task design and effective posture training on lifting, regarding the weighting of various shelves.

Optimum Buoyant and Aerodynamic Lift for a Lifting-Body Hybrid Airship

The central problem of a hybrid airship design, the optimum apportionment of the total lift between the static buoyant lift and the aerodynamic lift, is studied. The lift apportionment is carried out for specific lifting-body shape represented by a and . Different flight strategies have been analyzed. Optimal configurations have been obtained for various flight-time constraints and cruise altitudes. The result of the study is a set of hybrid airships with optimal apportionment of total lift along with optimal flight profile. The set has been presented in the form of a design chart, and an optimal hybrid airship can be obtained, corresponding to a maximum flight time and a cruise altitude.

Using surface electromyography (SEMG) to classify low back pain based on lifting capacity evaluation with principal component analysis neural network method.

Low back pain (LBP) is a leading cause of disability. The population with low back pain is continuously growing in the recent years. This study tries to distinguish LBP patients with healthy subjects by using the objective surface electromyography (SEMG) as a quantitative score for clinical evaluations. There are 26 healthy and 26 low back pain subjects who involved in this research. They lifted different weights by static and dynamic lifting process. Multiple features are extracted from the raw SEMG data, including energy and frequency indexes. Moreover, false discovery rate (FDR) omitted the false positive features. Then, a principal component analysis neural network (PCANN) was used for classifications. The results showed the features with different loadings (including 30%, and 50% loading) on lifting which can be used for distinguishing healthy and back pain subjects. By using PCANN method, more than 80% accuracies are achieved when different lifting weights were applied. Moreover, it is correlated between some EMG features and clinical scales, on exertion, fatigue, and pain. This technology can be potentially used for the future researches as a computer-aid diagnosis tool of LBP evaluation.