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[en] Highlights: • A new smart U-shaped TENG based on liquid-solid contact electrification is proposed. • The complicated mechanical motions can be transmitted into liquid pressure and electricity signal by U-shaped TENG. • The U-shaped TENG can be working as smart multifunctional sensors to detect the displacement, pressure, torsion, and so on. A new smart U-shaped triboelectric nanogenerator (TENG) was reported basing on solid-liquid contact triboelectrification and the Pascal's law, in which the complicated mechanical motions can be transmitted into liquid pressure and electricity signal. The U-shaped TENG driven by inertial force and air flow is designed as an energy harvesting device to collect the mechanical energy with a stable peak output voltage and current of about 20 V and 400 nA, respectively. The relationship between the output performance and the water sliding conditions is investigated in detail with a stable peak output performance at the point of resonance. The U-shaped TENG can also be working as smart multifunctional sensors to detect the displacement, pressure, torsion, and so on. As a self-powered displacement sensor, the U-shaped TENG shows a high sensitivity of 0.91 V mm−1 and 8.50 nA mm−1. As a pressure sensor, it also exhibits a high sensitivity of 4.41 V kPa−1 and 72.94 nA kPa−1, respectively. This work expands the practical applications of the solid-liquid triboelectrification based TENGs for energy harvesting and smart sensors in wide fields with advantages of simple fabrication, low cost, portable and self-powered properties.
[en] Background. To date, bronchial diverticula have generally been treated as a pathological condition associated with chronic obstructive pulmonary disease (COPD), although only a limited amount of published information is available on the relationship between bronchial diverticula as depicted by multidetector computed tomography (MDCT) and airflow limitations. Purpose. To evaluate the relationship between airflow limitations and main bronchial diverticula in the subcarinal region using spirometry and thin-section MDCT. Material and Methods. A total of 189 consecutive adult patients were retrospectively evaluated based on spirometry and thin-section MDCT of the chest. All examinations were performed at our institution between June and October 2008. The study group included 70 women and 119 men with a mean age of 65 years (range 19-86 years). The relationship between the FEV1% and bronchial diverticula in the subcarinal region was analyzed (Student's t-test). Results. The indications for conducting the examinations were pulmonary diseases (82 patients), cardiovascular diseases (22), extrapulmonary malignancies (74), and other conditions (11). A total of 84/189 (44.4%) patients showed bronchial diverticula, and the FEV1% of 70/84 (83.3%) patients was above 70. The FEV1% of patients with lesions ranged from 26.0 to 97.8 (mean 76.8), whereas the range was 28.1-94.4 (mean 73.7) in those without lesions. There was no significant association between the FEV1% and the presence of subcarinal bronchial diverticula (P > 0.05). Conclusion. Our data demonstrate that thin-section chest CT commonly demonstrates main bronchial diverticula in the subcarinal region in patients without airflow limitations. We propose that the presence of a small number of tiny bronchial diverticula under the carina may not be a criterion for the diagnosis of COPD
[en] To maintain the optimum condition of Advanced Fuel Science Building in KAERI, this report is described leak tests for HEPA Filter of HVAC in this facility. The main topics of this report are as follows for: - Procurement Specification - Visual Inspection - Airflow Capacity Test - HEPA Filter Bank In-Place Test
[en] The scheme of an experiment and certain results of the interaction of a free air vortex tube with a surface are considered. A solution of a differential equation for a plane cross section of a quasisolid tubular vortex core whose density varies according to a polytrope law is analyzed
[en] The present study provides some experimental observations on the structural developments of bubbly flow and the void wave damping in vertical, circular channel with a large diameter, and discusses the channel size effect on them. It is observed that the developing mode of bubbly flow structures and its transition mechanism are influenced by the channel size as well as the bubble size, and that they are well revealed in the behavior of wave damping
[en] To investigate the flooding phenomenon in nearly horizontal pipes the experimental studies are performed in the facility with the length of 2160mm, with three different inner diameters of 40mm, 60mm, and 70mm, and with the various inclination angles. Air and water approximately at room temperature and at atmospheric pressure are used as test fluids. The local void factions are measured by the three conductance probes located at the inlet, middle, and exit of water flow, respectively. Two mechanisms governing the transition to flooding are proposed. The effects of pipe end geometry, pipe diameter, and inclination angle are investigated and the comparisons with the slug formation models are conducted. It is found in this study that the transition to flooding is originated from two mechanisms i.e. 'wave instability' and 'high head flooding', and two regions (sub-critical and super-critical) coexist if the air flow increases up to a criticalvalue. It is observed that large roll waves are grown to the critical amplitude in the sub-critical region, does not show any dustive growth phenomenon. When the void fraction in the sub-critical region is used as the parameter for the flooding criterion, Ishii's slug formation model predicts the data without systematid errors. On the other hand, when the voide fraction in the super-critical region is selected as the parameter, Taitel's slug formation model best fitsthe data. Data obtained in the condition of high head flooding are not in good agreement with the results predicted by the slug formation models. Also, the transition criterion to the onset of flooding is very sensitive to the inclination angle, and the effect of pipe end geometry on the onset of flooding is negligible
[en] We report the creation of a low flow rate sensor from PEDOT micro-hairs. The hairs are printed as pipette-defined depositions using a nanopositioning system. The printing technique was developed for fabricating structures in 2D and 3D. Here micro-hairs with diameters of 4.4 μm were repeatedly extruded with constant heights. These hairs were then applied to produce a prototype flow rate sensor, which was shown to detect flows of 3.5 l min−1. Structural analysis was performed to demonstrate that the design can be modified to potentially observe flows as low as 0.5 l min−1. The results are extended to propose a practical digital flow rate sensor. (fast track communication)
[en] The dielectric barrier discharge (DBD) is presently used in many fields, including plasma medicine, surface modification, and ozone synthesis; the influence of airflow on the DBD is a widely investigated topic. In this work, a hysteresis characteristic on the initiating and extinguishing boundaries is observed in a nanosecond pulsed DBD, which is sensitive to the variation in the airflow velocities and pulse repetition frequencies (PRFs). It is found that, at a certain airflow velocity, the initiating PRF is higher than the extinguishing PRF. This difference between the initiating PRF and the extinguishing PRF leads to a hysteresis phenomenon on the initiating and extinguishing boundaries. When the airflow velocity is increased, both the initiating and extinguishing PRFs are increased and the difference between the initiating PRF and the extinguishing PRF also increased. The hysteresis width between the initiating and extinguishing boundaries is enhanced. To explain these results, the physical processes involved with the seed particles and the mechanisms of forming discharge channels are discussed. (paper)
[en] This study led to the development of an electro-coaxial air blown spinning system, which involves using a sheath-core nozzle for electrospinning, and the authors examined how the morphology of the fabricated nanofiber changed according to four process parameters. When the morphology changes of the nanofiber were analyzed using different process parameters, the increase in air flow rate was accompanied by the decrease in fiber diameter owing to shear force. On the other hand, as the concentration of the solution increased, the diameter of the nanofiber increased owing to the force of attraction between polymer chains. In addition, the diameter of the nanofiber decreased at a higher voltage owing to increasing orientation and the whipping phenomenon. Finally, when the tip to collector distance (TCD) was too close, it was difficult to obtain a perfect fiber, and the fiber produced in such a scenario was excessively thick and flat. However, when the TCD exceeded a certain value, no change in diameter of the nanofiber was observed. An intelligent prediction model needs to be developed to apply the results of this study to real processes.
[en] This paper deals with the effects surrounding phenomenon of a mechanical force generated on a high voltage asymmetrical capacitor (the so called Biefeld-Brown effect). A method to measure this force is described and a formula to calculate its value is also given. Based on this the authors derive a formula characterising the neutral air flow velocity impacting an asymmetrical capacitor connected to high voltage. This air flow under normal circumstances lessens the generated force. In the following part this velocity is measured using Particle Image Velocimetry measuring technique and the results of the theoretically calculated velocity and the experimentally measured value are compared. The authors found a good agreement between the results of both approaches