Maximum Total Force Research Articles

Effect of patient-specific scapular morphology on the glenohumeral joint force and shoulder muscle force equilibrium: a study of rotator cuff tear and osteoarthritis patients.

Introduction: Osteoarthritis (OA) and rotator cuff tear (RCT) pathologies have distinct scapular morphologies that impact disease progression. Previous studies examined the correlation between scapular morphology and glenohumeral joint biomechanics through critical shoulder angle (CSA) variations. In abduction, higher CSAs, common in RCT patients, increase vertical shear force and rotator cuff activation, while lower CSAs, common in OA patients, are associated with higher compressive force. However, the impact of the complete patient-specific scapular morphology remains unexplored due to challenges in establishing personalized models. Methods: CT data of 48 OA patients and 55 RCT patients were collected. An automated pipeline customized the AnyBody™ model with patient-specific scapular morphology and glenohumeral joint geometry. Biomechanical simulations calculated glenohumeral joint forces and instability ratios (shear-to-compressive forces). Moment arms and torques of rotator cuff and deltoid muscles were analyzed for each patient-specific geometry. Results and discussion: This study confirms the increased instability ratio on the glenohumeral joint in RCT patients during abduction (mean maximum is 32.80% higher than that in OA), while OA patients exhibit a higher vertical instability ratio in flexion (mean maximum is 24.53% higher than that in RCT) due to the increased inferior vertical shear force. This study further shows lower total joint force in OA patients than that in RCT patients (mean maximum total force for the RCT group is 11.86% greater than that for the OA group), attributed to mechanically advantageous muscle moment arms. The findings highlight the significant impact of the glenohumeral joint center positioning on muscle moment arms and the total force generated. We propose that the RCT pathomechanism is related to force magnitude, while the OA pathomechanism is associated with the shear-to-compressive loading ratio. Overall, this research contributes to the understanding of the impact of the complete 3D scapular morphology of the individual on shoulder biomechanics.

Numerical Study on Wave Dissipation and Mooring Force of a Horizontal Multi-Cylinder Floating Breakwater

A three-dimensional numerical model was established based on ANSYS-AQWA (R19.0) software for the purpose of analyzing the hydrodynamic characteristics of a floating breakwater. This study examines three distinct floating breakwaters with different cross-sectional designs in order to evaluate their respective wave dissipation capabilities. It is suggested that the horizontal multi-cylinder floating breakwater exhibits a superior ability to dissipate waves when compared to both the single-cylinder and square pontoon configurations and can be deemed the most advantageous shielding strategy for potential engineering applications. Subsequently, this study examines the effects of influential parameters, including a large cylinder diameter, a small cylinder diameter, the angular position of the small cylinder, and the height and period of the incident wave, on the wave transmission coefficient. An empirical formula for the wave transmission coefficient was derived based on the numerical results. Additionally, the effects of influential parameters, including wind speed, current velocity, incident wave height and period, and water depth, on the maximum total mooring force were investigated. Furthermore, an empirical formula for the maximum total mooring force is proposed for practical implementation in engineering.

Optical force conversion and conveyor belt effect with coupled graphene plasmon waveguide modes.

We propose a double-layer graphene sheets side coupling to a strip of graphene to obtain the optical pulling or pushing force. Combined with coupled mode theory and finite-difference time-domain simulations, it is found that the conveyor belt effect can be realized in conjunction with the lateral optical equilibrium effect upon the radiation loss κe equal to the intrinsic loss κo. The maximum total optical force acting on the strip in the symmetric mode (S-mode) can be up to ∼5.95 in the unit of 1/c and the anti-symmetric (AS-mode) mode reach ∼2.75 1/c. The optical trapping potential Ux and optical trapping force Fx for the S-mode have a value around -22.5 kBT/W and 240 pN/W, while for the AS-mode can up to ∼-56 kBT/W and 520 pN/W, respectively. Our work opens a new avenue for optical manipulation with potential applications in optoelectronic devices and lab-on-a-chip platforms.

Assessing lower extremity loading during activities of daily living using continuous-scale physical functional performance 10 and wireless sensor insoles: a comparative study between younger and older adults

PurposeThis study aims to investigate the lower extremity loading during activities of daily living (ADLs) using the Continuous Scale of Physical Functional Performance (CS-PFP 10) test and wireless sensor insoles in healthy volunteers.MethodsIn this study, 42 participants were recruited, consisting of 21 healthy older adults (mean age 69.6 ± 4.6 years) and 21 younger healthy adults (mean age 23.6 ± 1.8 years). The performance of the subjects during ADLs was assessed using the CS-PFP 10 test, which comprised 10 tasks. The lower extremity loading was measured using wireless sensor insoles (OpenGo, Moticon, Munich, Germany) during the CS-PFP 10 test, which enabled the measurement of ground reaction forces, including the mean and maximum total forces during the stance phase, expressed in units of body weight (BW).ResultsThe total CS-PFP 10 score was significantly lower in older participants compared to the younger group (mean total score of 57.1 ± 9.0 compared to 78.2 ± 5.4, respectively). No significant differences in the mean total forces were found between older and young participants. The highest maximum total forces were observed during the tasks ‘endurance walk’ (young: 1.97 ± 0.34 BW, old: 1.70 ± 0.43 BW) and ‘climbing stairs’ (young: 1.65 ± 0.36 BW, old: 1.52 ± 0.28 BW). Only in the endurance walk, older participants showed a significantly higher maximum total force (p < 0.001).ConclusionThe use of wireless sensor insoles in a laboratory setting can effectively measure the load on the lower extremities during ADLs. These findings could offer valuable insights for developing tailored recommendations for patients with partial weight-bearing restrictions.

Does Kinesio taping of tibialis posterior or peroneus longus have an immediate effect on improving foot posture, dynamic balance, and biomechanical variables in young women with flexible flatfoot?

BackgroundFlexible flatfoot is common in young adults. One of its causes is the failure of dynamic stabilizers, which play an important role in the medial longitudinal arch support, and their appropriate function is necessary for the integrity of the lower extremity and the spine. ObjectiveThe study aimed to determine Kinesio taping on which extrinsic foot muscle provides greater benefit regarding enhancement of foot posture, dynamic balance, and biomechanical parameters in functional tasks immediately. MethodsThirty women were recruited for the study. They were randomly divided into groups (A = 15, B = 15). In group A, Kinesio taping was applied on the tibialis posterior (TP), and in group B, Kinesio taping was applied on the peroneus longus (PL) and remained for 30 min. Outcome measures were the navicular drop test (NDT), foot posture index (FPI), Y-balance test, and biomechanical parameters in functional tasks. Before/After within-group and between-group comparisons of outcome measures were performed. ResultsNDT and FPI decreased in both groups (p < 0.05) with no significant difference between groups. In group A, maximum total force of the stance phase (MaxTFSP) during running increased, and some temporal parameters were changed. (p < 0.05). In group B, Y-balance test improved in all directions, and the width of the gait line during walking increased. There were no significant differences in the postural stability parameters in the within-group comparison, except for mean center of pressure displacement in group B (p = 0.04). ConclusionKinesio taping of both muscles could improve foot posture. TP Kinesio taping can increase the MaxTFSP during running and alter some temporal parameters during walking and running tasks. PL Kinesio taping could lead to better dynamic stability and coordination during dynamic tasks. Each muscle can be considered a therapeutic target for a specific purpose.

Preseason Eccentric Strength Is Not Associated with Hamstring Strain Injury: A Prospective Study in Collegiate Athletes.

Established risk factors for hamstring strain injuries (HSI) include older age and prior HSI. However, these are nonmodifiable and have a limited role in injury prevention. Eccentric hamstring strength is a common component of HSI prevention programs, but its association with injury is less clear. This study aimed to determine if eccentric hamstring strength was prospectively associated with HSI among collegiate athletes, while controlling for sex, age, and prior HSI. We hypothesized that athletes with lower eccentric hamstring strength or greater between-limb strength asymmetry at preseason would have an increased risk of HSI. Hamstring eccentric strength measures, maximum total force ( FTotal ) and between-limb asymmetry in maximum force ( FAsym ), were measured at preseason on male and female athletes. HSIs were tracked over the subsequent 12 months. Generalized estimating equations were used to identify univariable and multivariable associations between athlete demographics, eccentric hamstring strength, and HSI risk. Data for 326 athletes (85 female; 30 track, 43 basketball, 160 American football, 93 soccer) were included, and 64 HSIs were observed. Univariable associations between eccentric hamstring strength and subsequent HSI were nonsignificant ( FTotal : odds ratio [OR], 0.99 (95% confidence interval (CI), 0.93-1.05); P = 0.74; FAsym : OR, 1.35 (95% CI, 0.87-2.09); P = 0.23). No relationship between eccentric hamstring strength and HSI ( FAsym : OR, 1.32 (95% CI, 0.84-2.08); P = 0.23) was identified after adjusting for confounders including sex, age, and prior HSI. No association between preseason eccentric hamstring strength and risk of subsequent HSI was identified after controlling for known risk factors and sex among collegiate athletes. Eccentric hamstring strengthening may continue to serve as a preventative approach to HSI, but it does not provide additional insight into HSI risk beyond factors such as age and prior HSI.

The Immediate Effect of Static Hamstring Stretching on Dynamic Balance and Gait Biomechanical Variables in Athletes With Hamstring Tightness: A Preliminary Study

Introduction: Flexibility is an essential component of muscle function, and insufficient muscle flexibility may lead to muscle injuries. Decreased hamstring flexibility is one of the frequently reported risk factors for a hamstring strain and diminished athletic performance. Stretching is a commonly used intervention for increasing muscle length. There is a lack of evidence concerning the possible effects of hamstring stretching in balance and gait biomechanics. So, this study was designed to investigate the potential effects of static hamstring stretching on the range of motion (ROM), dynamic balance, and biomechanical variables of gait in athletes with hamstring tightness. Materials and Methods: This study is a single-group, pretest-posttest clinical trial performed on semi-professional female athletes. Twelve female athletes aged 20 to 35 years with bilateral hamstring tightness received a single session of unilateral static hamstring stretching on their randomly selected side. All subjects were assessed for straight leg raise, popliteal angle (using standard goniometry), perceived hamstring tightness (using a visual analog scale). They completed single-leg standing and 15-m walking and running tasks before and immediately after the intervention. The biomechanical parameters, including gait-line length, swing duration, and stance duration in walking tasks, maximum total force and mean total force in running task, and center of pressure (COP) displacement and standard deviation during balance task were measured using OpenGo sensor insole system. The pre-post values were compared using the paired sample t-test, and the level of significance was 0.05. Results: The values for straight leg raise and popliteal angle significantly increased (P&lt;0.05) compared with the baseline, while perceived tightness significantly decreased following stretching (P&lt;0.001). The amplitude (P₌0.006) and standard deviation (P₌0.016) of COP displacement in the mediolateral direction during the single leg stance balance task were significantly decreased after the intervention. Stance duration in slow walking (P₌0.004), as well as stance duration (P₌0.012) and swing duration (P&lt;0.001) in fast walking, were significantly decreased (P&lt;0.05) after stretching. No change was observed in gait biomechanical variables during the running test (P&gt;0.05). Conclusion: The results of this study indicate that static hamstring stretching can be a promising intervention not just for increasing hamstring flexibility but also for improving balance ability.

Probabilistic Tsunami Hazard Assessment in Meso and Macro Tidal Areas. Application to the Cádiz Bay, Spain

Tsunami hazard can be analyzed from both deterministic and probabilistic points of view. The deterministic approach is based on a “credible” worst case tsunami, which is often selected from historical events in the region of study. Within the probabilistic approach (PTHA, Probabilistic Tsunami Hazard Analysis), statistical analysis can be carried out in particular regions where historical records of tsunami heights and runup are available. In areas where these historical records are scarce, synthetic series of events are usually generated using Monte Carlo approaches. Commonly, the sea level variation and the currents forced by the tidal motion are either disregarded or considered and treated as aleatory uncertainties in the numerical models. However, in zones with a macro and meso tidal regime, the effect of the tides on the probability distribution of tsunami hazard can be highly important. In this work, we present a PTHA methodology based on the generation of synthetic seismic catalogs and the incorporation of the sea level variation into a Monte Carlo simulation. We applied this methodology to the Bay of Cádiz area in Spain, a zone that was greatly damaged by the 1755 earthquake and tsunami. We build a database of tsunami numerical simulations for different variables: faults, earthquake magnitudes, epicenter locations and sea levels. From this database we generate a set of scenarios from the synthetic seismic catalogs and tidal conditions based on the probabilistic distribution of the involved variables. These scenarios cover the entire range of possible tsunami events in the synthetic catalog (earthquakes and sea levels). Each tsunami scenario is propagated using the tsunami numerical model C3, from the source region to the target coast (Cádiz Bay). Finally, we map the maximum values for a given probability of the selected variables (tsunami intensity measures) producing a set of thematic hazard maps. 1000 different time series of combined tsunamigenic earthquakes and tidal levels were synthetically generated using the Monte Carlo technique. Each time series had a 10000-year duration. The tsunami characteristics were statistically analyzed to derive different thematic maps for the return periods of 500, 1000, 5000, and 10000 years, including the maximum wave elevation, the maximum current speed, the maximum Froude number, and the maximum total forces.

Investigations on the wind force and flow of a scaffolding system

ABSTRACT A scaffolding system model at one side of the exterior surfaces of a square building was set in the wind tunnel to measure the wind forces on the system in various oncoming-flow directions. The scaffolding system with additional clad sheets at three porosity ratios was tested to examine its wind load effect. Moreover, numerical computations were performed to examine the wind flow in the region between the building surface and the impermeable clad sheet. Results show that a decrease of screen porosity generally promotes varies wind force with the oncoming-flow direction variation. As the scaffolding system is at the windward side of the building, a maximum total push-in force occurs. When the system is parallel to the oncoming-flow direction, the total pull-out force becomes maximum. The cross-sectional maximum and minimum net pressure values mostly occur near the edge or the corner of the scaffolding system. Among all oncoming-flow directions, finally, cross-sectional large wind speeds usually occur at the upstream upper corner in the scaffolding system. The most critical situation that endangers the safety of construction workers due to the occurrence of local gust wind can happen when the oncoming-flow direction angle is within the range of 60 to 90 degrees.

Shake table experimental study of curved bridges with consideration of girder-to-girder collision

It is well-known that curved bridges are vulnerable to girder unseating during strong earthquakes. This is mainly attributed to its irregular geometry and seismic pounding. In this paper, a shake table experiment was designed and conducted on a 1/25-scale model to investigate the influence of collision between adjacent girders on the seismic response of curved bridges. For this purpose, two curved bridges with an expansion joint in-between were taken as the engineering background. Three historical records including a near-fault pulse-like record, a non-pulse-like record and a far-field ground motion were used to excite the test model. The seismic responses of the tested curved bridges were discussed in detail. Impact forces were measured by three load cells installed at the expansion gap joint. To begin with, the model was excited by the near-field pulse-like record in a variety of input directions without seismic collision to identify the most unfavorable input angle of the ground motions. It was found that for the test model, the secant direction of the adjacent two piers of the single-span segment is the most unfavorable input angle for seismic excitations. It was also found that the collision frequently occurred at the corners of the girders and was non-uniform along the contact surface. In addition, the girder-to-girder collision could induce significantly large in-plane rotation of the adjacent bridges, which could substantially increase the global displacement demands of the bridges. Furthermore, the maximum total impact forces increased with the gap size from 1 mm to 2 mm and then decreased with the gap size from 2 mm to 4 mm. However, the maximum in-plane rotation decreased with the gap size from 1 mm to 4 mm regardless of the input motions. Compared with the non-pulse-like near-fault motions, the pulse-like near-fault motions can result in higher in-plane rotation and force demands due to their velocity pulses and hence are more detrimental to curved bridges.

Numerical prediction of ice rubble field loads on the Norströmsgrund lighthouse using cohesive element formulation

An attempt has been made to predict the ice rubble field load on Norströmsgrund lighthouse by using Cohesive Element (CE) formulation. Two sub-load events were selected to validate the numerical and material model used in simulation of interaction of the ice rubble field and lighthouse. A literature review of simulation of rubble field structure interaction methods is also included in order to illustrate the knowledge gaps and highlight shortcomings of existing techniques. A description of chosen ice rubble field load events and signal post processing is added. A linear Mohr-Coulomb material model was used for the bulk element. For the cohesive element formulation, a material model was chosen which is based on three irreversible mixed-mode interaction with an arbitrary normalized traction-separation law governed by a load curve. The elastic modulus and fracture toughness for the ice rubble field were scaled using the ice rubble field porosity. A parametric study was conducted, and effects were documented. The numerical model predicted similar values for maximum total force, but average and standard deviation values of total force were higher than measured. The observed load drops in measured force time histories were reproduced with reasonable accuracy in simulated force time histories.

Spatiotemporal characteristics of the dam-break induced surge pressure on a vertical wall

ABSTRACT In this study, the impact process on a vertical wall due to the dam-break-induced surge was investigated experimentally. The entire surge impact process is classified into three stages, i.e. the initial impact stage, the reflected stage, and the second impact stage. Meanwhile, the wall is vertically divided into the bottom impact zone and the upper outer zone. In the initial impact stage, the upper turbulent and the lower steady splash-ups occur. Only the steady splash-ups induce horizontal pressures on the wall. In the reflected stage, a pressure oscillation occurs, which can be estimated using the pressure oscillation model. Pressure distribution in the impact zone has a large vertical gradient only in the initial impact stage. Surge force exerting on the bottom impact zone remains large in the entire process, whereas surge force in the outer zone is important only in the reflected stage. The maximum total force is equally contributed by the impact and outer zone components. A modified water wedge model was proposed, which predicts the pressure-rising process reasonably. The solid body assumption is suitable only for the turbulent splash-ups in the outer zone, which however is oversimplified for the steady splash-ups movement in the impact zone.

Operational fatigue loading on tidal turbine blades using computational fluid dynamics

As the world moves to a greater reliance on renewable energy, a vital component will be the predictability and dependability of the energy source; tidal energy provides such a solution. Horizontal axis tidal turbines are the most mature technology of all the marine renewable energy devices currently under development, as full-scale porotypes are already being tested and operated. As the industry develops and strives for commercial viability, it is becoming increasingly vital to develop a robust understanding of the complex interaction between the tidal flow, turbine blades and the support structure. This study uses an advanced computational fluid dynamics model to explore the operational fatigue loadings induced on tidal turbine blades. Two factors are considered, the presence of a support structure and varying vertical velocity profile of the tidal current. In order to perform the investigation, a model of a concept 16 m diameter horizontal axis tidal turbine with a monopile support structure is created. An investigation of the operational fatigue loadings due to variations in the positioning and the diameter of the support structure, the tidal turbine blade loads were found to varying by up to 43% of the maximum total thrust force.

2D Hypersonic Scramjet Inlet Geometry of Mach 7 using CFD

In the era of space transportations there is a huge demand on space technology to improve on cost reduction and take the heavy loads into space. Thus the load carrying capacities will be increase with this air breathing engines. This work gives a report on the design, analysis of optimal 2D scramjet engine inlet operating at Mach 7 without use of movable geometry. A computational study for scramjet inlet with different ramp angles is carried out. Several cases are considered to compress the air by rounding leading edge without moving the whole cowl up and down, by fixing the cowl lip and assuming axisymmetric inlet with rounded edge. The numerical tests are conducted to obtain maximum total pressure recovery, drag force and outlet Mach number for given flight condition. Two dimensional effects are studied with Navier-strokes approach to compute the pressure and Mach number at a different location. Oblique shock waves, expansion waves and shock wave interactions are primarily focused. Computational Fluid Dynamics (CFD) solver is used; steady flow simulations are carried out for inlet geometries with one, two, three and four ramps. Geometrical shape is redesigned based on oblique shock wave analysis. The corrected model is tested on Fluent with boundary layer considerations that the theoretical analysis is not able to cover. Lastly, a conclusion summarizing the design process is drawn and the optimal model is recommended for the Mach 7 inlet with different ramps with contraction ratio 10. It had been observed that two ramp scramjet inlet model has been preferred to use which has optimum pressure recovery and lower drag.

Jumping Joints: The Complex Relationship Between Osteoarthritis and Jumping Mechanography

We investigated the relationship between lower limb osteoarthritis (OA) and muscle strength and power (assessed by jumping mechanography) in UK community-dwelling older adults. We recruited 249 older adults (144 males, 105 females). OA was assessed clinically at the knee according to ACR criteria and radiographically, at the knee and hip, using Kellgren and Lawrence grading. Two-footed jumping tests were performed using a Leonardo Mechanography Ground Reaction Force Platform to assess maximum muscle force, power and Esslinger Fitness Index. Linear regression was used to assess the relationship between OA and jumping outcomes. Results are presented as β (95% confidence interval). The mean age of participants was 75.2 years (SD 2.6). Males had a significantly higher maximum relative power during lift off (mean 25.7 W/kg vs. 19.9 W/kg) and maximum total force during lift off (mean 21.0 N/kg vs. 19.1 N/kg) than females. In adjusted models, we found significant associations in males between clinical knee OA and maximum relative power [− 6.00 (CI − 9.10, − 2.94)] and Esslinger Fitness Index [− 19.3 (− 29.0, − 9.7)]. In females, radiographic knee OA was associated with total maximum power [− 2.0 (− 3.9, − 0.1)] and Esslinger Fitness Index [− 8.2 (− 15.9, − 0.4)]. No significant associations were observed for maximum total force. We observed significant negative associations between maximum relative power and Esslinger Fitness Index and clinical knee OA in males and radiographic knee OA in females. We have used novel methodology to demonstrate relationships between muscle function and OA in older adults.

Applications of Morison's equation to circular cylinders of varying cross-sections and truncated forms

Abstract Morison's equation is used for formulating forces and moments due to waves acting on circular cylinders of varying cross-sections and truncated forms. First, the usual case of bottom-mounted constant-diameter circular piles extending from seabed to free surface is revisited and then forces and moments for the truncated form are formulated. Further, linearly and parabolically varying diameter cases are considered for both bottom-mounted and truncated cylinders. The formulations are derived using linear wave theory; however, by adopting a heuristic nonlinear approach integrals are evaluated from pile bottom to wave crest instead of still water level. Corresponding linear formulations are obtained as special cases by simply setting the non-dimensional nonlinearity parameters to zero. Thus, for each cylinder configuration two different force and moment formulas are presented by integrating to actual free surface and to still water level. All the results are arranged in forms which are practically easy to use. Finally, analytical expressions for determining maximum total force and moment values are given and sample calculations are presented for all configuration types.

EVALUATION OF WAVE ATTENUATION BY FLEXIBLE CONTAINER BREAKWATER

A flexible container breakwater FCB, is made of a flexible membrane which filled with sand-water slurry. It is proposed for use in shallow water to attenuate wave energy in non-frequent storm sites and as temporary deployments, instead of costly traditional breakwaters. Experimental studies were carried out under irregular waves mainly in a wave flume and another limited runs in a wave basin. The purpose is to evaluate FCB stability criteria and wave dissipation capabilities. Filling the FCB with slurry with 40% sand was found safe enough against floatation forces. Also, It keeps the system in position under subaerial condition at Hs=1.50 m &Tp=5.5 s and Hs=1.9 & Tp=7.0 s waves according to the FCB bottom contact width. For higher waves, it need be moored by a belt in which the maximum total force is estimated as 2% of its net weight under subaerial conditions and 4% under submergence ratio 0.15. The dissipation coefficient, within the tests program, reached to 80%. Finally, important parameters affecting the efficiency were discussed and its range of applications was proposed.

Stability analysis of a non-conventional breakwater for wave energy conversion

This paper presents the stability analysis of a non-conventional breakwater cross-section integrating an overtopping wave energy converter, named OBREC. The device consists of a traditional rubble-mound breakwater in which the upper part of the armour layer is replaced by a smooth ramp and a reservoir.The analysis of the structure is carried out by combining model scale experiments and numerical simulations based on the Volume-Averaged Reynolds Averaged Navier-Stokes (VARANS) equations.The numerical analysis is used to complete and extend the results of the physical model test campaign, providing a deeper understanding of the pressure distribution and resultant force behaviour in locations where laboratory measurements were difficult to obtain or not available. Results show that the maximum vertical and horizontal total forces on the device are not simultaneous. At the time instant of the maximum total horizontal force, the vertical force is zero or directed downward, due to the significant positive contribution of the force acting on the sloping ramp. Additional numerical simulations show the influence of the submerged ramp length on the forces acting on the structure using the global and local stability analysis. The presence of the shaft contributes positively to the global stability against the sliding failure mode by reducing the uplift force exerted on the horizontal base. Moreover, the stability analysis shows that the critical conditions for the global failure modes occur at different time instants.

Numerical investigation of the hydrodynamic performance of a multi-column tension-leg-type floating wind turbine under effects of waves

The wind energy resource is one feasible supplement for renewable energy developments. The abundant offshore wind resource is of growing interest for wind power generation. Considering the economics, the floating structure is an ideal choice for the sustaining foundation of offshore wind turbine in deep water region. In this paper, a numerical wave tank is established to investigate the hydrodynamic performance of a multi-column tension-leg-type floating wind turbine (WindStar). To validate the numerical model, wave loads and mooring loads on the floating structure and the corresponding dynamic responses for the cases of different relative angles of the wave direction and the symmetric line of the structure are computed and compared with the measured data of model experiments. Both numerical simulations and model tests show that the responses of surge and sway are critical to the stability of WindStar. The mean value of the maximum total forces on the lower pontoon is the biggest one among that on other components and that on center column is the smallest one. The maximum wave loads acting on the lower pontoon, front column and center column are not sensitive to the wave direction when the relative angle is smaller than 30 degree. The maximum value of the tensions is not uniform among that acting on the tethers. The tension of tether5 reaches the maximum value in the case of the relative wave direction is 30 degree. The computed results of the wave loads and dynamic responses of the offshore wind turbine in regular waves provide several basic criterions for the optimization of WindStar.

Tibiofemoral Contact Forces in the Anterior Cruciate Ligament-Reconstructed Knee.

To investigate differences in anterior cruciate ligament-reconstructed (ACLR) and healthy individuals in terms of the magnitude of the tibiofemoral contact forces, as well as the relative muscle and external load contributions to those contact forces, during walking, running, and sidestepping gait tasks. A computational EMG-driven neuromusculoskeletal model was used to estimate the muscle and tibiofemoral contact forces in those with single-bundle combined semitendinosus and gracilis tendon autograft ACLR (n = 104, 29.7 ± 6.5 yr, 78.1 ± 14.4 kg) and healthy controls (n = 60, 27.5 ± 5.4 yr, 67.8 ± 14.0 kg) during walking (1.4 ± 0.2 m·s), running (4.5 ± 0.5 m·s) and sidestepping (3.7 ± 0.6 m·s). Within the computational model, the semitendinosus of ACLR participants was adjusted to account for literature reported strength deficits and morphological changes subsequent to autograft harvesting. ACLR had smaller maximum total and medial tibiofemoral contact forces (~80% of control values, scaled to bodyweight) during the different gait tasks. Compared with controls, ACLR were found to have a smaller maximum knee flexion moment, which explained the smaller tibiofemoral contact forces. Similarly, compared with controls, ACLR had both a smaller maximum knee flexion angle and knee flexion excursion during running and sidestepping, which may have concentrated the articular contact forces to smaller areas within the tibiofemoral joint. Mean relative muscle and external load contributions to the tibiofemoral contact forces were not significantly different between ACLR and controls. ACLR had lower bodyweight-scaled tibiofemoral contact forces during walking, running, and sidestepping, likely due to lower knee flexion moments and straighter knee during the different gait tasks. The relative contributions of muscles and external loads to the contact forces were equivalent between groups.