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The development of turbofans with larger fan diameters, shorter inlets, and thinner walls forces the acoustic liners to be placed closer to the hot parts of engines. This experimental study investigates the combined effects of large thermal gradients, grazing flow and acoustic level on the impedance of liners. Previous studies have shown that a coupling between these three effects can exist. The objective is thus to understand the underlying coupled phenomena, in order to extract the driving parameters for a more accurate impedance modeling. In the ONERA B2A grazing flow acoustic liner facility, the flow temperature can be accurately regulated and several types of acoustic excitation can be provided. For the purposes of this study, a test section with a heating device is used to obtain a thermal gradient between the backplate and the perforated plate of the liner sample. Infrared (IR) thermography is used to measure the temperature distribution on the perforated plate. The measurement is conducted for several configurations, to determine in which conditions the coupling between thermal and acoustic dissipation effects exists. In particular, a possible control of surface temperature by high sound pressure level is highlighted. [ABSTRACT FROM AUTHOR]

Abstract A straw man is a form of fallacious argument that involves the distortion of an opponent's view in order to make it more extreme and therefore less acceptable, thus easier to attack. In three experiments, we assess linguistic factors that may influence the acceptability of straw men for addressees. In Experiment 1, we demonstrate that a straw man is more acceptable when the speaker's argument is attacked rather than his standpoint. In Experiment 2, we show that a straw man is more acceptable when it contains two arguments that are simply juxtaposed rather than linked by a causal connective indicating attributed content (i.e. the French puisque). In Experiment 3, we find that a straw man is more acceptable when it echoes the speaker's explicit rather than implicit meaning. Taken together, these experiments strongly indicate that the formulation of a straw man has an impact on its perceived acceptability. Our results thus open a new avenue of inquiry for studies assessing the role of linguistic factors on the acceptability of fallacies. Highlights • Experimental studies of linguistic factors influencing the straw man fallacy. • Evidence for the role of connectives in argumentative context. • Discusses difference between implicit and explicit echoes. [ABSTRACT FROM AUTHOR]

With the growing demand for oil energy and a decrease in the recoverable reserves of conventional oil, the development of viscous oil, bitumen, and shale oil is playing an important role in the oil industry. Bohai Bay in China is an offshore oilfield that was developed through polymer flooding process. This study investigated the pore-scale displacement of medium viscosity oil by hydrophobically associating water-soluble polymers and purely viscous glycerin solutions. The role and contribution of elasticity on medium oil recovery were revealed and determined. Comparing the residual oil distribution after polymer flooding with that after glycerin flooding at a dead end, the results showed that the residual oil interface exhibited an asymmetrical “U” shape owing to the elasticity behavior of the polymer. This phenomenon revealed the key of elasticity enhancing oil recovery. Comparing the results of polymer flooding with that of glycerin flooding at different water flooding sweep efficiency levels, it was shown that the ratio of elastic contribution on the oil displacement efficiency increased as the water flooding sweep efficiency decreased. Additionally, the experiments on polymers, glycerin solutions, and brines displacement medium viscosity oil based on a constant pressure gradient at the core scale were carried out. The results indicated that the elasticity of the polymer can further reduce the saturation of medium viscosity oil with the same number of capillaries. In this study, the elasticity effect on the medium viscosity oil interface and the elasticity contribution on the medium viscosity oil were specified and clarified. The results of this study are promising with regard to the design and optimum polymers applied in an oilfield and to an improvement in the recovery of medium viscosity oil. [ABSTRACT FROM AUTHOR]

Slipper's micro motions including the squeezing motion, spinning motion, and tilting motion have a significant impact on its lubricating condition and dynamic behavior. However, few experimental studies are on these micro motions within a real axial piston pump, especially the slipper's spinning motion. The experimental investigations on the slipper in the past mainly focused on the parameters of the oil film such as pressure, thickness, and temperature. The sensors were often installed in the fixed swash plate when the cylinder block was chosen to rotate. Alternatively, the sensors were mounted in the fixed modified slipper when the swash plate rotated. The biggest challenge of the direct measurements of these micro motions is the space limitation for the sensor installation due to the compact structure of axial piston pumps as well as the slipper's macro motion. This paper presents a new three-piston pump for the slipper test rig which can provide enough installation space for the sensor. To realize the cylinder block balance, a hold-down plate is first introduced into this three-piston pump. In addition, a detailed set of relevant equations is derived to evaluate the functionality of the hold-down plate. Finally, the slipper's spinning motion was measured directly and continuously using this three-piston pump, which confirmed the capability of the slipper test rig. [ABSTRACT FROM AUTHOR]

This work investigates the rheological properties of wood flour filled poly(lactic acid) at typical processing temperatures, i.e. 155°C, 165°C and 175°C, using a parallel plate rheometer run in oscillatory mode. Materials with three different filler loading levels (10, 20 and 30% wt.) are characterized together with the neat matrix. Considering the complex viscosity curves, it is found that a single master curve can be obtained, which allows to predict the viscosity of the material at any filler loading level and any temperature that are included in the interval tested. [ABSTRACT FROM AUTHOR]

The performance of a single-headed stud and group of studs embedded in steel-fiber-reinforced cementitious composites (SFRCC) were investigated by conducting push-out tests. A total of 16 specimens were tested with various parameters including diameter of studs, numbers of studs, gauge lengths, pitch lengths, and fiber volume fractions of SFRCC. The test results showed that the headed studs embedded in SFRCC ensured the failure mode of stud fracture even without using steel rebar in the slab. The studs densely arranged with the smallest pitch length permitted for installation provided more than 90% of the full shear strength of a single stud. Using nine studs densely arranged in an area allowing for only four studs in the current design code, the overall shear resistance was twice that of the conventional design. When the fiber volume fraction of SFRCC directly affects the ductility of the stud, it was found using a fiber volume fraction of 6% is most suitable. [ABSTRACT FROM AUTHOR]

The experimental study of a highly compressible porous material, made of cellulose fibers, and imbibed with water, during stress relaxation tests on a rheometer, shows that the material relaxes when kept at constant strain as long as there are open pores. Using the relaxation curves, the behaviour under compression can be divided into two distinct zones, a poro-elastic one and a purely-elastic one, bounded by the zero-porosity limit. In the poro-elastic zone, the "non-hookean" stress-strain curve is fitted using Spriggs' expression of the elastic modulus dependence with porosity. Therefore, the elastic modulus of the porous material is expressed as an exponential function with two parameters: the elastic modulus of the fibers and the initial porosity of the material. For the purely - elastic zone the variation of stress is expressed as a sum of the residual stress obtained from the continuity equation and a Hookean stressstrain variation of a thinner material with the elastic modulus of the fibers - determined previously. The relaxation curves are fitted with a relationship between the decay stress and time, approximated with three terms of Prony series expansion of the generalized Maxwell model. [ABSTRACT FROM AUTHOR]

When air flows through pipe systems that include a corrugated segment, a whistling tone is generated and increases in intensity with increasing flow velocity. This whistling sound is related to the particular geometry of corrugated pipes, which is in the form of alternating cavities. This whistling is an environmental noise problem as well as a possible structural danger because of the resulting induced vibration. This paper studies the whistling behavior of various pipe systems with a combination of smooth and corrugated pipes through a series of experiments. The considered pipe systems consist of two smooth pipes attached at the upstream and downstream ends of a corrugated segment. Experiments with smooth and corrugated pipes, which had inner diameters of 15.25 and 16.5 mm, respectively, and various lengths, were performed for flow velocities of up to approximately 30 m/s. The minimum and maximum Strouhal numbers ( S t ) obtained during our experiments were 0.25 and 0.38, respectively. For all pipe configurations investigated in this study, the lowest Mach number at which whistling was observed was 0.017, and the maximum was 0.093. The lowest frequency at which whistling was detected in our experiments was 650 Hz, and the highest was 3080 Hz. The results presented in the form of different variables and dimensionless parameters, including the frequency, Mach number, Strouhal number, and Helmholtz number. The average mode gap and number of excited acoustic modes were also taken into account for all considered configurations. The pipe systems with longer corrugated segments had broader whistling ranges than did configurations with shorter segments, indicating that the number of cavities inside the corrugated pipe has a direct effect on whistling. Increasing the smooth pipe length (either upstream or downstream) resulted in a decrease in the average mode gap between successive modes. The number of excited acoustic modes was primarily related to the corrugated segment length, but the smooth pipe length also had a pronounced effect on the excited modes for a constant corrugation length. The highest number of excited modes (13) was seen in the case of corrugated length 450 mm and smooth pipe length (either upstream or downstream) 400 mm while the lowest number of excited modes (1) was observed for corrugated length 250 mm and smooth pipe length (downstream) 300 mm and 400 mm. [ABSTRACT FROM AUTHOR]