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Numerical simulations are conducted to investigate the impacts of airfoil thickness, the angle of attack and camber on the airfoil-gust interaction noise in transonic flows where locally supersonic regimes and terminating shocks are present. The conclusions about the geometry effects based on the extensively studied subsonic cases are revisited. With the increase of airfoil thickness, the sound generation is reduced in the downstream direction as in subsonic flows. More sound is produced in the upstream direction for thicker airfoils due to the non-uniform mean flow and shocks in the near field. The compensative effect makes the overall sound reduction by the airfoil thickness less than the subsonic cases despite the significant difference in the radiation patterns. The acoustic responses to the single frequency gusts are sensitive to the airfoil angle of attack in transonic flows. However, the overall differences are reduced when multiple wavenumber components are superposed in isotropic turbulence, and the sound pressure levels are therefore close as in subsonic flows. Similarly, the significant variations in single frequency acoustic responses by airfoil camber are averaged by the superposition of various wavenumber components. However, apparent variations are still found in the upstream direction, especially for the turbulences with small integral length scales. [ABSTRACT FROM AUTHOR]

Development in production technology has increased the need for high productive efficiency and effective utilization of machines. Tires, paper, rexin, and other rubber-based products are produced by using calendar roll machines. Web wrinkling, torn material, misaligned cutting, slitting, poor adhesion and laminate characteristics are the major errors in a calendar roll machine. The geometry, camber of rollers play a major role for most of the errors stated. This paper focuses on the experimental investigations carried out for cambering the rolls in-site (without removing), through grinding process with newly modeled equipment. The results obtained through in-site grinding are compared and discussed. It is observed that in-site grinding reduces the machine idle time by three-fourth of the normal roll grinding process and avoids the machine characteristic errors. New equipment comfortably eliminates the wrinkles and improves the quality of the rubber-coated fabric with the variation in thickness only between 1 and 2 µm. [ABSTRACT FROM AUTHOR]

Abstract The performance of a 5 kW three-bladed H-rotor Darrieus Vertical Axis Wind Turbine with cambered Tubercle Leading Edge NACA 0025 blades was established using computational fluid dynamics. 3D models and simulations of the VAWT were realized using CAD and CAE software, after which post-processing analyses provided understanding of the VAWT and blade flow physics. Results showed the TLE to be detrimental to flow and performance of a cambered VAWT. Using torque, lift and drag data, the cambered TLE VAWT was shown to deviate significantly against the cambered VAWT over one complete converged rotation. Cambered TLE VAWT blades encounter reduced lift forces and increased drag forces leading to lowered and eventual reversal of torque values. The z-vorticity and Q-criterion visualizations further supported the numerical results with the post-processed images showing vortices the size of the blade chord generated at blade wakes of the cambered TLE. The vortices emanate from the flow separation at the blade crests creeping in at the blade trailing edge at 75° azimuth and reaching halfway through the blade chord length at 106° azimuth. Spanwise separation was observed to be restricted at blade crests. The resulting flow degradation translated to the poor performance of the wind turbine. Highlights • Tubercle leading edge is detrimental to flow and performance of a cambered VAWT. • 3D model validation against reference studies achieved with a transitional 2D model. • Lowered lift and increased drag due to the tubercles reversed blade torques. • Vortices at blade wakes of tubercle leading edge blades caused torque degradation. • Flow separation creeps in and develops at tubercle leading edge blade troughs. [ABSTRACT FROM AUTHOR]

Body text Keywords Body text Review policy Body text Reader comments Body text The American Association of State Highway and Transportation Officials' AASHTO LRFD Bridge Design Specifications have a refined method for the calculation of time-dependent losses in prestressing force. This method estimates a gain in the prestressing force due to differential shrinkage between the precast concrete girder and the cast-in-place deck; however, it does not consider the possibility of cracking in the deck. Some state departments of transportation believe that after the deck cracks, the gain in the prestressing force is lost, and they do not include it in the prestress loss calculations. Some other state departments of transportation believe that not all of the prestress gain is lost and allow some percentage of the gain to be retained. This study focuses on the effect of deck cracking on the long-term loss of prestressing force. A finite element software model was used to simulate three different girder lengths with varying deck concrete strengths, differential shrinkage parameters, and girder ages at the time the deck was placed. When the girder age at the time of deck placement is more than 60 days, there is a high probability that the deck will crack, though a deck placed on a girder of any age may crack, depending on the properties of the deck and girder. When the deck cracks, some of the gain of prestressing force is lost, but the percentage lost depends on the extent of cracking in the deck. The older the girder is when the deck is placed, the greater the cracking. The cracked deck still provides some restraint, and even in cracked decks, nearly 50% of the prestress gain due to differential shrinkage was retained. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of fully tensioned top strands and inclusion of mild reinforcing steel on prestress losses and camber of pretensioned bridge girders. The results show that the inclusion of both fully tensioned top strands and mild reinforcing steel in the precompression zone reduced both short-term and long-term camber by 72% in the prestressed concrete bridge designs that were studied. Furthermore, the inclusion of both fully tensioned top strands and mild reinforcing steel have small but beneficial reduction in prestress losses. Prestress losses were estimated for a prestressed concrete bridge made with Type IV bridge girders spanning 103.33 ft (31.5 m). Five methods were used to estimate losses, including both the AASHTO LRFD Bridge Design Specifications approximate method and refined method. The newly developed Jayaseelan time-step method is presented and compared with other methods. The results show that all five methods estimate prestress losses that were within 2% of one another. [ABSTRACT FROM AUTHOR]

Abstract As wind energy technology is growing rapidly in the energy production sector, Vertical Axis Wind Turbines (VAWTs) are coming to the fore to tackle areas with low wind speeds. The choice of optimum configuration of these VAWTs can not only maximize their performance but is a deterministic feasibility factor for their deployment. In this study, the Joukowski airfoil is reconsidered as potential rotor airfoil for VAWT. Its performance is compared against classical symmetrical NACA0012 and cambered NACA4312 blades. The investigation is carried out using high resolution CFD modelling. Results reveals the higher performance of the Joukowski airfoil over the classical symmetrical and cambered NACA. This dominance assessed by the attained higher blade lift as well as higher torque and power coefficient almost over the entire operable tip speed ratio. It was also found that cambered blades, improve the overall performance of the VAWT compared to the symmetrical baseline with a better power coefficient, at a lower tip speed ratio. In general, the rotor develops more consistent and homogenized torque at a higher tip speed ratio. The attained improvement in the torque using Joukowski however negatively affected the self-starting ability of the VAWT. [ABSTRACT FROM AUTHOR]

Flatness is an important quality characteristic for rolled products. Modern hot rolling mills are equipped with actuators that can modify the uneven thickness distribution across the width of the strip (crown), taking into account online measurements of various process parameters such as temperature, force and exit strip profile, either automatically or manually by the operator. However, the crown is also influenced by many parameters that cannot easily be measured during production, such as work roll temperature evolution through thickness and roll geometric variation due to thermal expansion (thermal camber). These have an impact on the strip flatness. In this paper, a thermo-mechanical finite element model on LS-DYNA™ software was utilized to predict the influence of process parameters, and more specifically strip temperature, cooling strategy (application of cooling on the entry or entry and exit side simultaneously) and roll core temperature, on the evolution of roll temperature and thermal camber. The model was initially validated with industrial data. The results indicate that the application of both entry and exit cooling is ~30% more efficient compared to the entry cooling only, thus the thermal camber will be reduced by 2 μm. A hotter roll (380 K) is more stable compared to the cold roll (340 K), showing also an improvement of 2 μm. The hotter roll will also reach a thermal steady state on the surface faster compared to the colder one, without making a significant difference on the steady state temperature. Strip temperature plays a roll in the thermal camber evolution, but it is a less important parameter compared to cooling strategy and roll temperature.

Alpine skis have changed dramatically in the last century. Long and straight wood skis have evolved into shorter lengths and now contain a plethora of modern materials. Shaped skis have become the norm. Today’s skis also offer a variety of waist widths and shapes to cater to specific uses. By studying how skis have evolved, it is possible to gain insight into how the design of alpine skis has progressed. To do so, the mechanical properties of 1016 skis, from the 1920s to 2019, were measured with a machine developed at the University of Sherbrooke. The resulting data are used to calculate various geometric, stiffness and performance parameters. The evolution of these parameters over the years is analyzed. This analysis provides a better understanding of the evolution of ski design and shows when the introduction of new materials and shaping concepts has changed the way skis are designed.

The present paper undertakes kinematic and dynamic analysis of front suspension sys-tem. The investigated model is a full-scale Macpherson which is a multibody system. Two degree of freedom model is considered here to illustrate the vertical displacement of sprung mass and unsprung mass with using displacement matrix. Ride and handling parameters including displacement of sprung and unsprung masses, camber/caster angle, and track changes are derived from the relationships. Moreover, geometrical model and equations are validated by Adams/Car software. The kinematic and dynamic re-sults have been compared in both analytical and numerical outputs for verification. The proposed analytical model shows less than 5% differences with a complicated multibody model. [ABSTRACT FROM AUTHOR]

In Canterbury New Zealand, chip seal is the primary surface material for rural state highways. The roads are designed to accommodate various types of traffic; traffic that has grown steadily over the past decade. The growth in dairy and logging, two of New Zealand’s main exports, resulted in a large rise in milk and logging trucks. This significant increase in traffic has led to a significant amount of pavement failure due to rutting which predominantly occurs in the outside wheel path rather than the inside. This paper provides a review and analysis of LTPP data at two rural sites. Data from these sites show more rutting in the outside wheel path than the wheel path close to the crown of the road. Contributing factors observed from the literature are included in this paper and it was shown that the main contributing factor to rutting is load (traffic). Road pavements are constructed to be homogeneous but anecdotally it is known that using camber or a crown will divide the load from traffic more towards the outside wheel. Some general factors that increase the difference are the axle width, and height of the centre of mass, the camber percentage and present rutting depth. Calculations show that the difference in load on the left and right wheel can lead to quite different ESAL values compared to values calculated based on the average load. In fact, an example using Austroads shows that the ESAL value can almost double if actual wheel loads are used. It also shows that there are no other mechanisms that adequately account for this difference. [ABSTRACT FROM AUTHOR]

Flapping-Wing Micro Air Vehicles (FW-MAVs) are small hand-held flying vehicles that can maneuver in constrained space owing to its lightweight, low aspect ratio and can fly in low Reynolds number environment. In the present study, the aerodynamic characteristics such as time-averaged lift camber wings with different five wind tunnel models having 6, 9, 12, and 15% camber were developed are compared with those of a flat wing to assess the effects of camber wing on the aerodynamic performance for flapping flight applications. The experiments were performed in an open circuit wind tunnel with of non-return airflow with a test section of (0.3m x 0.3m) and capable of speeds from 0.5 to 30 m/s. The time-averaged lift as functions of advance ratio of the flapping motions with respect to the incoming flows are measured by using a strain gauge balance and KYOWA PCD-300A sensor interface data acquisition system. It is found that camber would bring significant aerodynamic benefits when the flapping flight is in unsteady state regime, with advance ratio less than 1.0. The aerodynamic benefits of camber are found to decay exponentially with the increasing advance ratio. Cambered wing show significantly higher lift in comparison with the flat wing. [ABSTRACT FROM AUTHOR]

Numerical modeling of the prestressing element that generates prestressed effect in beams has always been considered a big challenge. This research compares two methods of modeling; In the first method we used initial stresses predefined stress and in the second method we used the temperature strain. Concrete damage plasticity model (CDP) was used to model the non-linear behavior of concrete material and an elasto-plastic behavior was applied to ordinary and prestressed reinforcement. Truss elements were used to model ordinary and prestressed reinforcement embedded inside the concrete. As a result, Initial Temperature load method showed less error in bottom and top stresses and cambering of beam in comparison with the basic concept method, than predefined method.

Strip end flip is an instability phenomenon in finishing rolling process. It often occurs upon steel strip end being released from the work rolls of a previous mill stand. Undesirable motion of steel strip such as side walk may cause strip hitting the side guides located at the entrance of a subsequent mill stand and result in a flip phenomenon of strip end. As a result, it may cause folding of the strip end and seriously damage the finishing roll surface. This would significantly deteriorate the strip quality and impede yield rate. Statistically, the occurrence of strip end flip is usually less than 5% during finishing rolling, yet due to lacking of regularity and difficulty in observation, this phenomenon has been a troublesome issue in finishing rolling. We intend to reproduce the strip end flip phenomenon by exploring a numerical simulation on a finishing mill model based on observation and on empirical on-site data collected from production line. By evaluating the effect of the parameters and the boundary conditions on the severity of the strip end flip, an interpretation of the phenomenon and on the possible mechanisms is explored. By tuning the roll alignment and by varying the degree of camber, a realistic reproduction of the strip end flip was realized. The simulated phenomenon was in good trend with the on-site video image. The strip end flip was mainly attributed to the effect of camber of the strip, the alignment of the rolls played a less significant role. The so far exciting outcome of the numerical simulation provides a feasible way to systematically explore the mechanisms of the strip end flip and to keep this problem under control. [ABSTRACT FROM AUTHOR]

Extra long span rail transit bridges are generally slender and sensitive to excitations, and alignment control of the bridges should be conducted during construction. In this paper, the self-adaptive Kalman Filter (SKF) method was applied to the alignment control of the second longest rail transit bridge in the world. Each influential factor of the bridge alignment was firstly introduced. Then, the finite-element analysis and field tests of the bridge were carried out to obtain the influential factors that induced bridge cambers quantitatively. Combining with the cambers, the SKF method was applied to the alignment control of the bridge. Comparisons of the SFK-predicted alignment with the target alignment or the field measured alignment were carried out. Results show the SKF for alignment control of bridges is feasible and reliable. [ABSTRACT FROM PUBLISHER]

Wind energy technology has seen steady growth in the energy market as a clean, renewable source of energy. This has brought attention to areas with moderate wind energy potentials. Darrieus type Vertical Axis Wind Turbines (VAWTs) allow capturing of this potential for energy production at a cost-effective scale. To improve the performance of these turbines their design needs to be optimized. With better manufacturing methods currently available cambered blades are being investigated to improve the performance of these turbines. In particular, turbine solidity is investigated in this paper due to different airfoil chord lengths and different number of blades. The analysis is conducted following high fidelity CFD modeling in unsteady, turbulent regimes in Arbitrary Lagrangian Eulerian formulation accounting for the sliding/rotating rotor's domain configuration that emphasizes the role of rotor blades interaction. The study showed that low solidity turbines with cambered blades operate at low coefficients of performance (C P ) over a large range of tip speed ratios (TSRs). High solidity turbines, with solidity close to unity, have much higher C P, but at smaller TSRs and a short range of TSRs. Medium solidity turbines, as well as turbines with solidity greater than unity, are faced with considerable interaction which compromises their operation at TSRs as low as one. The larger chord length helps improve the torque production of the turbine. The change in number of blades leads to a large dispersed wake behind the rotor which is unfavorable for deployment of an array of turbines. [ABSTRACT FROM AUTHOR]

Transversal displacements of metal in the hearth of deformation reduce unevenness of elongations across strip width, wherein the camber curvature becomes smaller, and its radius is larger than that calculated on the assumption of plane deformation scheme. The investigations are based on the variational principle of possible changes of strain state (Jourdain principle). It is assumed that the input velocity unevenness of the metal flow in the hearth of deformation across the strip width passes into an output one proportionally to reductions. Further, velocities and powers of deformation and displacements of metal in the hearth of deformation during hot rolling and corresponding powers are calculated. Solving Euler-Poisson's equation, we receive the expression for coefficients, which take into account the influence of the transversal displacements of metal on decreasing the output unevenness and the radius of camber curvature for every harmonic. [ABSTRACT FROM AUTHOR]

The aim of this paper is to report the results of the fluid–structure interaction study of a lightly cambered blade in a cascade under the influence of various inflow conditions and structural parameters, in a cost–effective manner. This work could be viewed as a preliminary design tool that provides the behavioral trend of the blade motion which will be useful when a detailed analysis has to be performed. The methodology employed to formulate the aerodynamic model for lightly cambered airfoils follows the Whitehead's aerodynamic theory for a cascade of flat plates. The aerodynamic loads acting on a blade in a cascade of airfoils are computed to provide the required conditions for the structural model. The aeroelastic model thus formulated is employed to predict the structural response of a blade in a cascade subjected to both steady and unsteady flows. The possibilities of a blade undergoing pure bending or torsion, or coupled bending–torsion flutter are investigated in the present study. The utility of the already developed aerodynamic model is demonstrated by investigating the structural behavior of three different blade curvature profiles – Double Circular Arc (DCA), NACA 65, and NACA a = 1.0 mean lines. The effects of various blade structural parameters such as mechanical damping, center of gravity and elastic axis offset, and cascade geometric parameters such as stagger angle and blade spacing on the blade aeroelastic response are analyzed. The flutter boundary for a range of frequency ratios is then examined. It has been found that compressor blades with frequency ratios close to unity are vulnerable to coupled bending–torsion flutter under the influence of an incoming steady flow. The growing torsional vibrations are in general registered for higher values of air velocity compared to the range of velocities favoring bending flutter. The influence of different compressor unsteady flows – rotating stall and surge, on the aeroelastic behavior of a lightly cambered blade is also examined in the present study. [ABSTRACT FROM AUTHOR]

A cambered surface that is moving forward in a fluid generates lift. To explain this interesting fact in terms of simpler models, some preparatory concepts were discussed in the first part of this article. We also agreed on what is an acceptable explanation. Then some popular models were discussed. Some quantitative theories will be discussed in this concluding part. Finally we will tie up all these ideas together and connect them to the rigorous momentum theorem. [ABSTRACT FROM AUTHOR]

Prestressed concrete I-girders are subject to different load types at their construction stages. At the time of strand release, i.e., detensioning, prestressed concrete girders are under the effect of dead and prestressing loads. At this stage, the camber, total net upward deflection, of prestressed girder is summation of the upward deflection due to the prestressing force and the downward deflection due to dead loads. For the calculation of the upward deflection, it is generally considered that prestressed concrete I-girder behaves linear-elastic. However, the field measurements on total net upward deflection of prestressed I-girder after detensioning show contradictory results. In this paper, camber calculations with the linear-elastic beam and elastic-stability theories are presented. One of a typical precast I-girder with 120 cm height and 31.5 m effective span length is selected as a case study. 3D finite element model (FEM) of the girder is developed by SAP2000 software, and the deflections of girder are obtained from linear and nonlinear-static analyses. Only geometric nonlinearity is taken into account. The material test and field measurement of this study are performed at prestressing girder plant. The results of the linear-elastic beam and elastic-stability theories are compared with FEM results and field measurements. It is seen that the camber predicted by elasticstability theory gives acceptable results than the linear-elastic beam theory while strand releasing. [ABSTRACT FROM AUTHOR]

The net rotor torque generated by a straight-bladed vertical axis wind turbine has temporal variation for an azimuth angle of the blade. The torque variation should be investigated to understand the performances of the wind turbine. The blade camber and thickness are important to determine the characteristics of the wind turbine. We have studied effects of the blade camber and thickness on the mean characteristics and temporal torque variation at any azimuth angle of the blade. The mean torque and power increase with the smaller camber and the larger blade thickness over relatively lower tip speed ratio. The maximum mean torque and power coefficient take the largest value at certain blade thickness. The maximum value of the torque variation emerges at an azimuth angle of the blade located in upstream, and it has significant contribution to the mean torque. In particular, over relatively lower tip speed ratio, the maximum value of the torque variation remarkably increases with the smaller camber and the larger blade thickness.

A redesign of canard control-surface of an advanced all-metallic fighter aircraft was carried out by using carbon fibre composite (CFC) for ribs and panels. In this study ply-orientations of CFC structure are optimized using a Genetic-Algorithm (GA) with an objective function to have minimum failure index (FI) according to Tsai-Wu failure criterion. The redesigned CFC structure was sufficiently strong to withstand aerodynamic loads from stress and deflection points of view. Now, in the present work CFC canard structure has been studied for its buckling strength in comparison to existing metallic design. In this study, the existing metallic design was found to be weak in buckling. Upon a detailed investigation, it was revealed that there are reported failures in the vicinity of zones where initial buckling modes are excited as predicted by the finite element based buckling analysis. In view of buckling failures, the redesigned CFC structure is sufficiently reinforced with stringers at specific locations. After providing reinforcements against buckling, the twist and the camber variations of the airfoil are checked and compared with existing structure data. Finally, the modal analysis has been carried out to compare the variation in excitation frequency due to material change. The CFC structure thus redesigned is safe from buckling and aerodynamic aspects as well.

With wind energy technology growing rapidly in the energy production sector, Vertical Axis Wind Turbines (VAWTs) are coming to the forefront, to tackle challenges in areas with low wind speeds. It is of great importance to know the optimum configuration of these VAWTs to maximize their performance. In this study, cambered blades are investigated using high fidelity CFD modelling under unsteady, turbulent regimes using arbitrary Eulerian and Lagrangian approaches with sliding mesh configuration to gain more knowledge of their interactions and the effect on turbine performance. This study reveal that VAWT with cambered blades are at higher Coefficient of performance (Cp) compared to symmetrical bladed turbines. It was also found that the turbines achieved this higher Cp at lower tip speed ratios allowing them to combat low wind speed challenges. They also produce more consistent torque within a full rotor revolution. Moderate camber also improved the self-starting ability of the VAWT whereas, high camber negatively affected the self-starting capability due to the interactions between the blades. [ABSTRACT FROM AUTHOR]

A new bridge type called a spread slab-beam bridge was developed recently by using the same concept as that used for spread box beam bridges, in which the beams are spaced apart. This paper presents an evaluation of the new bridge system in terms of design and constructability and investigates the challenges encountered during construction. Forty-four bridge geometries were designed by using standard Texas DOT (TxDOT) slab-beam types to determine the feasible design space. One of the most aggressive geometries with widely spaced slab beams was constructed at full scale. On the basis of the research findings, it was concluded that spread slab beams with a topped panelized deck provide a viable construction method for short-span bridges. Results of a shear-design check show that the standard interface shear reinforcement must be doubled for the first quarter of the span length for more aggressive designs. Larger-than-expected camber of the precast slab beamsmight cause construction challenges and delays. A 30% increase in standard camber estimates can be used for construction purposes. High differential temperatures together with drying shrinkage might lead to early-age longitudinal deck cracking. Care should be taken during concrete curing to avoid factors that contribute to large temperature changes in the deck. [ABSTRACT FROM AUTHOR]

The low-temperature co-sintering technique for the fabrication of the multi-layered electrolyte supported on a planar anode substrate is demonstrated for solid oxide fuel cells (SOFCs). A NiO/gadolinia-doped ceria (GDC) anode substrate is fabricated using tape casting and lamination processes, and yttria-stabilized zirconia (YSZ) bottom electrolyte and GDC top electrolyte layers are sequentially screen-printed, followed by co-sintering at 1230 °C. The electrolyte layers are successfully densified at an extremely low processing temperature by promoting the sinterability of the individual components, and a continuously graded electrolyte structure is constructed to suppress the delamination of the electrolyte films. Based on the camber analysis, the cell structure is optimized to minimize the structural distortion and eliminate the processing defects. The low-temperature co-sintering technique presented in this study is expected to widen the material selection and resolve the compatibility issues associated with high-temperature processing for the fabrication of SOFCs. [ABSTRACT FROM AUTHOR]

Camber evolution and stress development of low-temperature cofirable dielectric and ferrite laminates were investigated as a function of the heating rate and the thickness ratio of two layers. Isotropic uniaxial viscosities of individual layers were determined through a vertical sintering technique by in-situ measuring shrinkage curves via an optical dilatometer. Sintering mismatch stresses as a result of the densification rate difference were calculated by using the as-measured curvature of bilayers. A good agreement was achieved in the evolution laws of experimentally measured and theoretically predicted cambers and stresses. However, quantitatively analyzed data indicated obvious differences between experimental results and theoretical predictions, especially where high heating rates and small thickness ratios of dielectric to ferrite layers were adopted. This discrepancy was ascribed to the porosity gradients and preferred pore orientations in the cofired layers as a result of the existing mismatched stresses. [ABSTRACT FROM AUTHOR]

In this work, we presented in detail the design procedure of the front double A-arm push rod suspension system for a formula student race car. The type of suspension systems used generally are reviewed. The CAD models of the components in the suspension system are made using SolidWorks ® and the Finite element analysis of the components is done using ANSYS ® Workbench. Both kinematic and dynamic analysis of the designed suspension system is performed. The results of vibration or ride analysis and roll steer analysis are also presented for the designed suspension system. The method for spring design is elucidated. This work emphasizes the method for designing and analyzing the suspension system for a race car in various aspects. [ABSTRACT FROM AUTHOR]

VAWT (Vertical axis wind turbines) pose several advantages over the horizontal axis machines that make them more suitable for applications where wind conditions are inherently turbulent. However, due to the complexity of VAWT aerodynamics, technical literature on the subject is very limited with research on VAWT performance mostly focused on steady wind analysis. This paper aims to numerically predict the performance of a 5 kW VAWT under fluctuating wind conditions through computational fluid dynamics modeling. Two dimensional VAWT models using symmetric and cambered blades were created with open field boundary extents. Fluctuating wind speed was imposed on the inlet with average magnitude of 5 m/s, amplitude of fluctuation of 10%, and frequency of fluctuation of 1 Hz. Results revealed that fluctuating wind imposes a detrimental effect on VAWT performance. A VAWT blade with 1.5% camber shows the best performance with the cycle-averaged unsteady power coefficient at 0.31 versus the optimum steady power coefficient of 0.34. In spite of increased available wind power due to the fluctuating wind at 233.13 Watts in one wind cycle compared to 229.69 Watts for the steady 5 m/s wind case, power generated by the camber bladed VAWT drops to 74.96 Watts from the steady wind rotor power of 78.32 Watts. [ABSTRACT FROM AUTHOR]

In the recent years a vast of experimental work with non-metallic reinforcement is being widely used to explain a comprehensive structural integrity of composite material as an alternative for construction industry purposes. The objective of this research was to experimentally investigate serviceability limit state aspects related to flexural behavior of concrete beams internally prestressed with glass fiber-reinforced polymer (GFRP) bars. Such characteristics as the effect of prestressing force and reinforcement ratio on corresponding deflection as well as cracking distribution have been mainly governed by the stress–strain principles of reinforced concrete. The experimental results are compared to theoretical estimates from formulas available in U.S. and European codes and recommendations. [ABSTRACT FROM AUTHOR]

The study of temperature distribution along width of stripes in the Hot Rolling Mills HRM 2000 line was carried out in collaboration of NLMK Hot Rolled Production specialists with students and lecturers of the Lipetsk State Technical University. This study was made using a portable thermal scanner BALTECH TR-1400. It was marked that the surface temperature increased from the right edge of the strip to the left in relation to rolling direction. The temperature distribution asymmetry along the width of the strip is one of the reasons for camber, wedging and flatness of hot-rolled strips. [ABSTRACT FROM AUTHOR]

The present work aimed to reveal morphological characteristics of worker honeybee (Apis mellifera) wings and demonstrate the function of resilin on camber changes during flapping flight. Detailed morphological investigation of the wings showed that different surface characteristics appear on the dorsal and ventral side of the honeybee wings and the linking structure connecting the forewing and hindwing plays an indispensable role in honeybee flapping flight. Resilin stripes were found on both the dorsal and ventral side of the wings, and resilin patches mostly existed on the ventral side. On the basis of resilin distribution, five flexion lines and three cambered types around the lines of passive deformation of the coupled-wing profile were obtained, which defined the deformation mechanism of the wing along the chord, i.e. concave, flat plate and convex. From a movie obtained using high-speed photography from three orthogonal views of free flight in honeybees, periodic changes of the coupled-wing profile were acquired and further demonstrated that the deformation mechanism is a fundamental property for variable deformed shapes of the wing profile during flapping flight, and, in particular, the flat wing profile achieves a nice transition between downstrokes and upstrokes. [ABSTRACT FROM AUTHOR]

Decreased physical activity in mammals increases bone turnover and uncouples bone formation from bone resorption, leading to hypercalcemia, hypercalcuria, bone loss and increased fracture risk. Black bears, however, are physically inactive for up to 6 months annually during hibernation without losing cortical or trabecular bone mass. Bears have been shown to preserve trabecular bone volume and architectural parameters and cortical bone strength, porosity and geometrical properties during hibernation. The mechanisms that prevent disuse osteoporosis in bears are unclear as previous studies using histological and serum markers of bone remodeling show conflicting results. However, previous studies used serum markers of bone remodeling that are known to accumulate with decreased renal function, which bears have during hibernation. Therefore, we measured serum bone remodeling markers (BSALP and TRACP) that do not accumulate with decreased renal function, in addition to the concentrations of serum calcium and hormones involved in regulating bone remodeling in hibernating and active bears. Bone resorption and formation markers were decreased during hibernation compared with when bears were physically active, and these findings were supported by histomorphometric analyses of bone biopsies. The serum concentration of cocaine and amphetamine regulated transcript (CART), a hormone known to reduce bone resorption, was 15-fold higher during hibernation. Serum calcium concentration was unchanged between hibernation and non-hibernation seasons. Suppressed and balanced bone resorption and formation in hibernating bears contributes to energy conservation, eucalcemia and the preservation of bone mass and strength, allowing bears to survive prolonged periods of extreme environmental conditions, nutritional deprivation and anuria. [ABSTRACT FROM AUTHOR]

This article focuses on the design, fabrication, testing, modeling, and validation of a spanwise variable camber section of a helicopter rotor blade. The lower surface skin was slit aft of the trailing edge spar and subjected to a spanwise warping actuation input. A kinematic linkage facilitates a corresponding chordwise motion of the skin along the span length (from zero at the no-camber end to maximum at the maximum camber end). Input warping actuation of 0.18 in length produced an 18° camber variation over a 45 in span section of a modified CH-46 blade. Finite element model predictions of the active camber section showed good agreement with benchtop test data for both the output camber for a given warping actuation input and the corresponding actuation force required. Finite element results suggest that some geometry distortions in the active camber section could be experienced due to the presence of centrifugal and aerodynamic loads, but these distortions could be alleviated with the introduction of a shear-flexible (but stiff through the thickness) core. [ABSTRACT FROM AUTHOR]

This study proposes a type of hard sail and investigates its potential use on commercial vessels for utilizing wind energy. We focus on the performance of cascade sails and consider the aerodynamic interaction between the sails. To obtain the lift and drag coefficients of the sails, wind tunnel testing and a two-dimensional simulation code based on the boundary element method with vortices are used. According to the change in distance and attack angle of each sail in the cascade, the best setup parameter is investigated, and the aerodynamic interaction is analyzed. From the viewpoint of the sailing performance of the vessel, our results demonstrate that cascade hard sails can significantly reduce fuel costs for commercial vessels. [ABSTRACT FROM AUTHOR]

Prestressed concrete wing-shaped members are frequently used in the construction of long-span roofs in precast concrete buildings. Roofs spanning more than 30 m (100 ft) are built by assembling a number of these thin-walled members. To optimize their design and take advantage of their potential load-carrying capacity, the transfer of large forces from the pretensioned strands to the concrete is critical. Information on the evolution of these forces and of the ensuing deformations is necessary, not only in the long run, but also immediately after concrete casting and during the first few weeks. The Department of Civil and Environmental Engineering of the University of Perugia in Italy and a major prefabrication firm of central Italy have completed an experimental program on pretensioned wing-shaped members to investigate the evolution of prestressing stresses and of camber during the different stages of concrete hardening. The result allowed the careful evaluation of the prestress losses that occur in the first three weeks during concrete placement and curing to emphasize the influence of the temperature history on the development of prestress losses and to calibrate suitable parameters for the prediction of camber growth. Numerical comparisons based on Eurocode 2 are also performed to check the reliability of the numerical procedure adopted by the authors and to ascertain whether using self-consolidating concrete (as in the manufacture of the specimens tested in this project) makes any sizeable difference with respect to the predictions based on Eurocode 2, which refers to ordinary concrete. [ABSTRACT FROM AUTHOR]

A semitrailer hit several overhead steel truss members ofthe Interstate 5 (I-5) bridge over the Skagit River in Washington State, causing the north span to collapse. An emergency design-build contract required reopening of the permanent replacement span within 90 days of notice to proceed. Precast, prestressed concrete decked bulb tees of sand-lightweight concrete and full flexure-shear flange connections kept the weight of the superstructure within 5% of that of the original steel superstructure, allowing the undamaged substructure to be reused. Careful control of the girder geometry maintained vertical clearance over the Skagit River. Temporary posttensioning enabled the girders to resist construction-induced stresses. The replacement span was assembled alongside the existing bridge and skidded into place during a single 19-hour closure of I-5. [ABSTRACT FROM AUTHOR]

This study aims to explore the effect of various design parameters, such as maximum airfoil thickness, maximum camber in the blade profile, maximum camber position, helical pitch, blade pitch angle, solidity, and number of blades, on the performance of helical Darrieus hydrokinetic turbines (HDHKTs). An experimental and numerical performance analysis was conducted, corresponding to free-stream velocity of 0.5 m/s. The performance increased with increasing airfoil thickness, up to a maximum of 21%. Effects of the maximum camber and position of the maximum camber on the performance of the turbine were insignificant. The analysis was extended to different helical pitch angles on the NACA 4421 profile. The performance increased with increasing helical pitch angle; however, the operating range of tip speed ratio decreased. The blade pitch angle had an insignificant effect on the turbine performance. Furthermore, the HDHKT of the NACA 4421 blade profile consist of two-, three-, four-, five-, and six-blade turbine performances was examined for different solidity values. For solidity values of 0.10, 0.15, and 0.20, the three-blade HDHKT performed the best. For solidity values greater than 0.20, the four-blade HDHKT performed the best. The four-blade HDHKT had the highest coefficient of power among all the HDHKTs. • Performance analysis is performed both experimentally and numerically for three-blade and four-blade HDHKTs. • Blade thickness effect of NACA 4421 is better among NACA 4412, NACA 4415, NACA 4418, NACA 4421, NACA 4424 and NACA 4428. • Increase in helical pitch angle within the range of 30° to 60°, the performance of NACA 4421 increases. • Maximum camber, position of maximum camber and blade pitch angle have insignificant effect on HDHKT performance. • For solidity 0.10. 0.15 and 0.20 three-blade HDHKT performed well and beyond this four-blade performed best. [ABSTRACT FROM AUTHOR]

The evaluation of long-term prestress losses and camber, taking into account the effect of creep, shrinkage, and relaxation, is essential for prestressed concrete bridges. An effort has been made in this paper to identify a suitable time-dependent creep coefficient and shrinkage strain models to estimate the long-term prestress losses and camber for an existing box-girder bridge span. Longterm prestress losses and camber are estimated using four different models for creep and shrinkage--ACI 209R-92, CEB MC90-99, GL2000, and B3--and the comparison has been made with field measurements. From the limited studies made, it is seen that for the initial 5 years after the construction of a bridge, the B3 model can be used for estimation of long-term losses, and the CEB MC90-99 model can be used for estimation of long-term camber . However, for a prestressed concrete beam, the ACI 209R-92 model is found to predict closer prestress loss values with laboratory measurements. [ABSTRACT FROM AUTHOR]

Use of 0.7 in. (18 mm) diameter strands at 2 × 2 in. (50 × 50 mm) spacing in pretensioned concrete girders results in an approximately 35% increase in the prestressing force compared with the same number of 0.6 in. (15 mm) strands and a 92% increase in the prestressing force compared with the same number of 0.5 in. (13 mm) strands, allowing for longer spans, shallower depths, and/or wider girder spacing. This paper presents the application of 0.7 in. (18 mm) diameter strands at 2 × 2 in. (50 × 50 mm) spacing to the Oxford South Bridge in Oxford, Neb. Twenty-six strand samples were tested for breaking strength, yield strength, and modulus of elasticity. The strands met the requirements of ASTM A416-07.Transfer lengths were measured at three locations on two girders at release and after 14 days. Measurements indicated that the transfer length of 0.7 in. diameter strands can be conservatively estimated using the AASHTO LRFD Bridge Design Specifications. All girders were monitored for end zone cracking and camber growth and were found in compliance with current production tolerances, as specified by PCI and the Nebraska Department of Roads. [ABSTRACT FROM AUTHOR]

In this study, we present a systematic approach for examining the effects of the design parameters of the side guide on camber, a phenomenon in which a material with a temperature gradient across its width is bent in the right or the left direction as the material is deformed in the roll gap. A series of finite element (FE) analyses were performed to provide a set of computed values for selected design parameters, such as (i) the length of the side guide, (ii) the diameter of guiding roller attached to the contact face of the side guide, (iii) the pitch of the guiding rollers and (iv) the interference of the guiding roller into the slab, that would decrease significantly the contact time between the slab and the side guide, and reduce the contact force between them. In the FE analyses, the actual sizes of the horizontal rolls (work rolls), vertical rolls (edgers) and side guide were modeled. Based on the results of the FE analyses, the side guide was designed and manufactured for installation in the POSCO No. 2 Hot Strip Mill. When the side guide was installed in front of work roll, camber was reduced dramatically by 57%. The design parameter that had the most influence on camber was the length of the side guide. In terms of side guide durability, the interference of guiding roller into the slab was the most dominant design parameter. [ABSTRACT FROM PUBLISHER]