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•experimental residence time measurements in a wiped film evaporator.•residence time distributions for different wiper types (roller and comb wiper).•influence of viscosity, liquid ...load and wiper speed on residence time distribution.•formation of a bow wave seems to be more pronounced when using a roller wiper.•comb wiper advantageous in terms of efficient heat & mass transfer at high viscosity.
Wiped film evaporators (WFEs) are characterized by small hold-up and short residence times, making them well suited for the separation of thermally sensitive substances and for fast chemical reactions. Since fluid dynamics and heat transfer in WFEs are highly interdependent, the effects of different wiper geometries, operating parameters and physical properties on the residence time behavior are manifold and poorly understood. In this work, the influence of liquid load, wiper speed and liquid viscosity on the residence time distribution (RTD) of a wiped liquid film was investigated. Tracer experiments were conducted without evaporation in a stainless steel WFE alternatively equipped with a spring-loaded comb wiper and a roller wiper. A detailed comparison of both wipers demonstrated that at a high liquid load and an increased viscosity, shorter residence times were achieved with the roller wiper, which could be explained by a strongly pronounced bow wave with an increased vertical flow velocity. Using a comb wiper, an increase in dispersion with rising liquid load at higher viscosity was demonstrated.
For automobile manufacturers, reducing vehicle interior noise is essential for increasing customer satisfaction and vehicle quality. Windshield wipers are one of the major components that generate ...such noises, and faulty wipers could negatively affect passengers' psychological and physiological perceptions while driving. Thus, identifying faulty wipers during the manufacturing process would improve the driving experience and vehicle and road safety as well as reduce driver distraction. However, the existing windshield wiper noise-detection process is entirely manual, relies upon human subjectivity, and is time-consuming. Accordingly, this paper develops a novel automated windshield wiper fault-detection system. First, a novel binarization approach is used to effectively binarize the transformed spectrograms of sound signals from windshield wiper operation to segment nAoisy regions. Then, a new matrix-factorisation approach called orthogonal binary singular value decomposition is proposed to decompose binarized mel spectrograms into uncorrelated binary eigenimages to extract meaningful features and identify faulty wipers. Then, the
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-nearest neighbour classifier is utilised to classify the extracted features into normal or faulty windshield wipers. Finally, to demonstrate the effectiveness of the proposed system, it was validated on real-life windshield wiper reversal and squeal noise datasets, where it outperformed existing methods and achieved accuracies of 95% and 94%, respectively.
In wet paper wiper, three-dimensional nonuniform wetting may occur and affect frictional behavior. This study aims to clarify the frictional behavior of wet paper wiper in order to develop guidelines ...for controlling the frictional behavior of similar products such as clothing and sponges. Friction tests were conducted between a paper wiper and a flat glass while varying the water content of the paper wiper. The friction coefficient reached a maximum at a certain water content depending on the normal load and sliding velocity conditions. This high-friction effect may be attributed to meniscus formation at the contact interface and inside the paper wiper specimen, because the negative pressure due to the meniscus can promote the expansion of the real contact area.
•The contact condition and friction between paper wiper and glass were examined.•The interface was partially or completely wetted by adding water.•Water droplets on the interface split and moved backward during friction.•The friction coefficient was maximum at a certain water content.•The high-friction effect was dependent on the normal load and the sliding velocity.
Various studies have been conducted over the years on how to reduce driver distractions while driving, but with little effort on the distraction that could be caused by manually operated wipers while ...driving whenever it rains. Drivers frequently take their hands off the steering to turn ON/OFF and adjust the wiper speed when driving during rain, which causes a loss of concentration and increases the risk of a car accident. This paper presents an automatic car wiper prototype system that adjusts the speed of the wiper based on the intensity of the rain. The system also includes an audio alert that warns the driver to stop driving during heavy rain. The rain sensor/intensity and servo motor; which regulates the wiper's speed, were interfaced by an ATMega328 (Arduino Uno A000066). It performed satisfactorily, with average response times of 0.78 seconds, 1.95 seconds, and 6 seconds for rain water detection, increasing rain intensity, and no rain detection respectively. The wiper speed was 15 rpm at moderate rain intensity and 32 rpm at heavy rain intensity. The wiper average response time and speed shows that it is a system that eliminate delay as compare to manually operated car wiper system. The developed system will reduce driver distractions while driving thereby reduces the risk of a car accident. As a result, this system can be combined with new technologies seen in contemporary vehicles.
•A hydrophobic TENG based on sisal cellulose paper(SCP) was constructed to collect raindrop energy.•Both physical and chemical hydrophobic modification can effectively improve the SCP's dielectric ...constant.•The hydrophobic SCP-TENG modified by the chemical method is more suitable than the physical method for collecting raindrop energy.•The output electrical signal of SCP-TENG and the raindrop velocity have linear relationship.•The hydrophobic SCP-TENG can be used as raindrop-based sensors.
Hydrophobic Sisal cellulose paper (SCP) was obtained by surface modification of SCP via physical adsorbing polymer and chemical grafting monomer, respectively. The influence of surface modification conditioning on the hydrophobicity, dielectric constant and dipole moment of the SCP was investigated. The results showed that the hydrophobicity and dielectric constant of the modified SCP increased with the concentration and amount of the modifiers. The output electrical performance of the TENGs assembled by the two types of hydrophobic SCP for rain energy collection was compared. The output electrical performance of the chemically modified hydrophobic SCP-TENG is higher than that of the physical modified. The maximum power density of the former reaches 8.2 mW/m2. Furthermore, based on the linear relationship between the output performance (output voltage intensity and output current intensity) of hydrophobic SCP-TENG and the droplet velocity, a raindrop-based sensor based on hydrophobic SCP-TENG was successfully constructed and estimated.
Improving the tribological properties of windscreen wipers to achieve high visibility and low wiping noise is crucial for safe and comfort driving on rainy days. This study systematically ...investigated the effects of microgrooves on the tribological properties of rubber, similar to that used in wiper blades, sliding against glass in the presence of water. It was found that grooves with an orientation angle of 0° were highly beneficial for the wiping process of rubber blades. At low velocities, the grooves reduced the frictional resistance and restrained the propagation of Schallamach waves; however, at high velocities, frictional resistance existed, restraining forced wetting. These findings have significant implications for the development of high-performance windscreen wipers.
•Wiping properties of wiper blades on wet windscreens were improved by microgrooves.•At low velocities the frictional resistance of wipers was reduced and propagations of Schallamach waves were restrained.•At high velocities forced wetting between rubber and glass was resisted, forming a superior sealing.
Sporadic Legionnaires' disease is frequently detected in commercial truck drivers. We report 2 sporadic cases of this disease in Barcelona, Spain, that occurred during December 2019 and September ...2020. Laboratory findings were consistent with windshield wiper fluid without added screen wash as a possible source of infection for both cases.
•Study the influence of the following parameters: feed rate, cutting speed and depth of cut on 3D surface roughness.•Optimal cutting conditions for each performance level are established.•The ranges ...of best cutting conditions adapted, were given.
This study considers the comparison between the surface roughness criteria (Ra, Rz and Rt) of the wiper inserts with conventional inserts during hard turning of AISI 4140 hardened steel (60 HRC).The planning of experiments was based on Taguchi’s L27 orthogonal array. The response surface methodology (RSM) and analysis of variance (ANOVA) were used to check the validity of quadratic regression model and to determine the significant parameter affecting the surface roughness. The statistical analysis reveals that the feed rate and depth of cut have significant effects in reducing the surface roughness. The optimum machining conditions to produce the best possible surface roughness in the range of this experiment under these experimental conditions searched using desirability function approach for multiple response factors optimization. The results indicate that the surface quality obtained with the wiper ceramic insert significantly improved when compared with conventional ceramic insert is 2.5. Roughness measurements reveal a dependence on CC6050WH tool wear. However, although the wear rises up to the allowable flank wear of value 0.3mm, roughness Ra did not exceeded 0.9μm.
•A 3DOFs theoretical model for analyzing the frictional vibration of a wiper-windscreen system is proposed.•An analytic formula of friction coefficient is used instead of single-valued function in ...traditional analysis.•The mechanism of the wiper-windscreen frictional vibration are theoretically and experimentally analyzed.•The effects of different wiping speeds and accelerations on reversal vibration are analyzed experimentally.
This paper studies the frictional vibration aspects of the automobile wiper-windscreen contact system and builds a numerical model that matches the test equipment. The reversal vibration of the contact system is examined by the dynamics part of a theoretical model with the derived analytical formulas. The fluid lubrication characteristics are investigated by the friction part of the model with solutions of the friction coefficient-negative slope formula for relative velocity and the friction coefficient formula in the time domain. The nonlinear dynamic response of the theoretical model of the wiper blade is calculated with the Runge-Kutta method and the results of the frictional vibration are well reproduced in real motions. The validity of the model is confirmed by parallel analyses of the simulated results and the experimental ones of the wiper-windscreen system. It is concluded that properly reducing the length of blade tip is an effective way to reduce vibrations of the system. The influences of the wiping speed and acceleration after reversal on the system vibrations are also analyzed through experimental investigations. The theoretical and experimental results presented in this paper can be reference to structural optimization of the wiper blade and vibration and noise control of the wiper-windscreen contact system.
•Axial DOC contributes most for wiper inserts’ tool life while machining Inconel 625.•Adhesion, BUE, attrition and chipping are the main wear mechanisms at low axial DOC.•Wiper inserts’ feed/tooth ...contributes most for surface roughness of Inconel 625.•An extended work-hardened subsurface layer is seen for max. tool life condition.
Ni-based superalloy Inconel 625, despite its extensive applications (in aerospace, oil and gas, marine, chemical processing and alike industry) is categorized as difficult-to-cut material due to distinct thermal and physical characteristics. Incidentally, the use of novel multi radii insert (wiper) geometry, that is reported to provide extended machining capabilities for different materials and machining scenarios has not been found to be reported for this alloy. This work employs PVD coated carbide inserts with novel wiper edge geometry for face milling of Inconel 625 under dry cutting conditions. Cutting speed, feed per tooth and axial depth of cut have been taken as input variables and machining performance is evaluated in terms of tool life, tool wear analysis, material removed and surface integrity aspects (namely roughness and microhardness). Taguchi L8 array has been employed for experimentation phase followed by post experimental analysis. It is found that for tool life, axial depth of cut is the most significant factor with contribution of 45.43%. Maximum tool life of 42.8 min was achieved when machining was done employing lower values of feed (0.08 mm/tooth) and axial depth of cut (0.25 mm) with higher value of cutting speed (45 m/min). For the case of surface roughness, feed/tooth is found to be the most contributing factor (PCR 46.25%). Results are found to be correlating well with the cutting temperatures generated during the process. Experiments with minimum axial depth of cuts resulted in lesser temperatures and better output parameters in general. Review of the wear pattern via SEM analysis indicate adhesion, BUE, attrition and chipping to be the main wear mechanism in general except where higher axial depth of cut (0.5 mm) was employed that culminated in fracture. For the conditions where maximum tool life was obtained, a work-hardened layer was observed beneath the machined surface extending up to ∼400 μm depth. An indirect comparison of the results with other literature reported face milling scenarios of Inconel 625 (where other tool types are employed), seems to indicate the effectiveness of wiper inserts employed herein. The results are well explained and supported by the physical phenomenon involved.
