Small Size Air Research Articles

Modeling and simulation of dew point temperature generated by a bubble aerator

The dew point temperature can be generated by saturating air with water vapor through several methods, one of which is by creating small-sized air bubbles passed through water in an enclosed space known as a saturator. In practical terms, the dew point temperature produced by this system can be determined by measuring it using a dew point meter. However, the prediction of the dew point temperature generated through theoretical approaches has not been presented before. Thus, in this study, a simulation has been conducted to determine the dew point temperature. The result is then compared to the experimental data. The experiment follows the single pressure humidity generator principle, where a saturator containing a bubble aerator is immersed in a stirred liquid bath. The bath temperature is set to 25 °C, and the gas flow rate is adjusted from 0.1 lpm to 0.4 lpm. The dew point temperature is measured using a 373 LHX chilled mirror dew point meter. On the other hand, the simulation is performed using the Monte Carlo method, and the physical model involves a heat balance between convection and the change in bubble energy. The convection heat transfer coefficient is determined by the behavior of bubble dynamics, which is related to the bubble size and bubble velocity. The dew point temperature obtained from the simulation is assumed to be the same as the bubble temperature. As a result, the simulation data align well with the experimental data.

Incidence of ultrasonographic signs of pneumothorax in asymptomatic neonates.

Pneumothorax in neonates can be life-threatening. In neonates without respiratory distress, spontaneous pneumothorax can also develop under certain conditions. To determine the incidence of ultrasonographic signs of pneumothorax in asymptomatic neonates using lung ultrasound as the diagnostic tool. This was an observational prospective study conducted at the Basurto University Hospital (Bilbao, Spain) between January 2018 and December 2020. Lung ultrasound was performed during routine examination of asymptomatic neonates admitted to the maternity ward. Of a total of 204 asymptomatic neonates included in the study, 21 (10.3%) presented ultrasound signs of pneumothorax (Group A), and 183 (89.7%) had a normal lung ultrasound (Group B). Lung ultrasound was performed after a mean of 19 h of life (range 9-34). The presence of A-lines behind the sternum in the anterior transverse plane, at the intermammillary level, was observed in 100% of patients in Group A compared to no cases in Group B (p < 0.0001). The neonates of Group A presented the lung point located in the midclavicular line, indicative of a mild air leak. Lung ultrasound allows precise detection of suspected small-sized air leaks that can be detected in asymptomatic neonates. The true incidence of pneumothorax in asymptomatic neonates may be substantially higher than previously described in the literature.

Spanish Airport Network Structure: Topological Characterization

Applied complex network theory has become an interesting research field in the last years. Many papers have appeared on this subject dealing with the topological description of real transport systems, from small networks like the Italian airport network to the worldwide air transportation network. A comprehensive topological description of those critical structures is relevant in order to understand their dynamics, capacities, and vulnerabilities. In this work, for the first time, we describe the Spanish airport network (SAN) as a complex network. Nodes are airports, and links are flight connections weighed by traffic flow. We study its topological features and traffic dynamics. Our analysis shows that SAN has complex dynamics similar to small-size air transportation networks of other developed economies. It shares properties of small-world and scale-free networks, and it is highly connected and efficient and has a disassortative pattern for high-degree nodes.

Novel fabrication processes for hollow fine particles and porous metals using fine bubble generation method with hollow ultrasonic horn

Fine bubbles with diameters of less than 100 μm are currently attracting considerable attentions because of their properties such as a large surface area per unit volume, low rising velocity, and self-pressurization due to surface tension. We found that fine bubbles with diameters of less than 100 μm can be easily generated by using a hollow cylindrical ultrasonic horn. Compared with to the conventional fine bubble generation method, which are wherein gas is supplying supplied gas to porous media and atomizing the gas is atomized with shear flow, this fine bubble generation method can generate small-sized air bubbles and mass circulation of the liquid phase is unnecessary. Therefore, this device is capable of generating MBs in any fluid, even in high-temperature, high-viscosity and high reactive materials. In this paper, we show the summary of fine bubble generation method using hollow ultrasonic horn, and also the example application of this method to fabrication process for hollow microcapsule and porous metals.

Observation of quadrocopters by radar with long-term coherent signal accumulation

The article discusses the experimentally obtained characteristics of radar signals reflected from small-sized aerial targets such as a quadrocopter, with their long-term coherent accumulation. A brief description of the structural diagram of the experimental radar and its characteristics is given. The radar operates in the ten-centimeter wavelength range and emits a coherent-pulse signal. The duration of the emitted chirp pulse is 1 μs with a compression ratio of 15. Algorithms for primary processing of signals in a computer are given, including compression of chirp signals and spectral analysis of the received implementation, which is equivalent to its coherent accumulation. The parameters of the generated radar image are determined. The characteristics of the targets used - the small-sized quadcopters Mavic and Phoenix – are given. As a result of the experiments, it was shown that the tested small-sized air targets in the ten-centimeter wavelength range of the probing signal have their own coherence time sufficient for the coherent accumulation of the signal reflected from them for a time of at least 0.2 seconds. The Mavic does not produce reflections from its rotating rotors. The main rotor of the Phoenix quadcopter creates spectral components in the image, concentrated along the speed axis in the form of maxima symmetrically located relative to the central mark of the target. The presence of this feature of the signal allows you to identify the type of target, highlight the target against the background of birds, and detect a stationary, hovering target. It is shown that the features of signals reflected from the ground, with long-term coherent accumulation, allow providing the minimum speed of the detected target, measured in fractions of a meter per second.

Tracking of small-sized air objects

Modern capabilities of tracking air objects are developing at a rapid pace. The article proposes a method for detecting and identifying small-sized air objects during their tracking.

Design of Fluorotellurite Microstructured Fibers With Near-Zero-Flattened Dispersion Profiles for Optical-Frequency Comb Generation

We present the design of fluorotellurite microstructured fibers (FTMFs) with near-zero-flattened dispersion profiles in the wavelength range of 1500–1600 nm for optical frequency comb (OFC) generation. The FTMFs are based on TeO2-BaF2-Y2O3 glass with a zero-dispersion wavelength of ∼2160 nm. The fiber core is surrounded by the two layers of air holes. The addition of large size air holes in the outer layer is to shift the zero-dispersion wavelength of the fiber from ∼2160 nm to the wavelength region of 1500–1600 nm. The addition of small size air holes in the inner layer is to make the dispersion profile of the fiber become flat in the wavelength range of 1500–1600 nm. By optimizing the parameters (the core diameter, the air hole size, the pitch of air holes, etc.) of FTMFs, the fiber with the chromatic dispersion value between −0.5 and 0.3 ps/nm/km in the wavelength range of 1500–1600 nm is achieved. Furthermore, numerical simulations are used to show the potential of the fiber for OFC generation via cascaded four-wave mixing. Flat top OFC extending from 1500 to 1600 nm with tunable mode spacing from 25 to 100 GHz can be generated in a 2-m-long fiber by using a 1550-nm laser with a pulse width of 0.85 ps and a peak power of 49 W as the pump source. The effects of stimulated Brillouin scattering on OFC generation are also investigated.

소형 공기청정기 하우징의 성형성 향상을 위한 런너시스템 설계 및 스크류 전진 거리 예측

The runner system of the injection mould and the injection volume of the injection molding process greatly affect the quality of the produced part. The goal of this paper is the design of the runner system and the prediction of the injection volume for the injection moulding of a housing part of small-size air cleaner to improve the formability through the three-dimensional injection moulding analysis. The effects of the runner system of the mould on the injection moulding characteristics are investigated. From the results of the investigation, a proper design of the runner system with uniform filling characteristics and the minimized defect formation is obtained. In addition, the influence of the moving distance of the screw on filling characteristics, weldline formation and deformation characteristics is examined. From the results of the examination, an appropriate moving distance of the screw for the housing part of small-size air cleaner is estimated.

Small-size downhole air drill hammers of increased capacity

The authors review key approaches to designing small-size air drill hammers. The approach to increasing impact capacity of air drill hammers by means of buildup of blow frequency is substantiated. The experimentally obtained and compared characteristics of air drill hammers equipped with the heads made of steel and titanium prove feasibility of increasing impact capacity by means of using low density materials. The technology of thermal treatment of a titanium-alloy hammer head is described, and its laboratory testing results are reported.

Ultrasonic scattering measurement of air void size distribution in hardened concrete samples

The size distribution of air voids in concrete has significant impacts on freeze-thaw damage. This study presented a non-destructive ultrasonic scattering technique to determine the air void size distribution in hardened concrete samples. The ultrasonic scattering theory was applied to calculate the theoretical attenuation of concrete by including the effects of the viscoelastic matrix and different sizes of air voids and aggregates. The air void size distribution was determined by using an inverse analysis to minimize the difference between theoretical and experimental attenuation of concrete. The logarithm normal distribution for large-size air voids and normal distribution for small-size air voids were selected to better represent the air void size distribution in concrete. Both the large-size range and small-size air void distributions were obtained with ultrasonic scattering techniques for hardened concrete specimens. These results were favorably compared with the petrography-based ASTM C 457 method. The comparisons indicated that the developed ultrasonic scattering technique can measure the size distribution of air voids in concrete for the evaluation of freeze-thaw durability.

Spider assemblages and dynamics on a seasonal island in the Pripyat River, Belarus

Spider assemblages on a seasonal river meadow island were studied in spring 2006 and 2007. Samples were collected with a set of 20-30 pitfall traps once every 5 days. Altogether, 1179 spiders belonging to 30 species were collected. There were 5 constant dominant species: medium-sized wandering Pardosa prativaga, and small-sized air colonizers Oedothorax retusus, Erigone dentipalpis, Oedothorax fuscus, and Pachygnatha degeeri. The relatively low species diversity was higher in 2007 and grew throughout the season with the lowering of the water level. The total turnover of species involved the least abundant species (below 1% of the total), mainly Linyphiidae. Abundance of small-sized species was negatively correlated with abundance of medium-sized species. The activity density of small-sized species was higher at the beginning of the spring season with O. Retusus being especially dependent on the high water level, while the number of medium-sized species and P. Prativaga were correlated with the water lowering. The assemblages of ground-dwelling spiders were exposed to seasonal and annual changes, but due to the proximity of refugia and rapid colonization, not all assemblages were affected. Spider dynamics on the seasonal island reflected a general activity pattern where, over time, small-sized species avoided larger predators, which were additionally stopped by high water levels.

Experimental study of small-size air turbo blower supported by externally pressurized conical gas bearings

This paper describes a several ten thousand rpm class small-size air turbo blower. This has been newly developed using externally pressurized conical gas bearings and blower impeller with centrifugal suction blades on both faces. This bearing can reduce the number of machine parts since it is possible to support the thrust and radial load components in both directions. Calculations of the characteristics were conducted and investigated using the manufactured test bearings. A test rig was manufactured, and the characteristics were experimentally verified. These bearings have a conical bearing surface with diameters of 10mm and 8mm and a length of 15mm. A pair of length is 30mm. The actual bearing clearances are 0.012mm and 0.014mm, respectively. The measured bearing characteristics agreed with the designed values. It was clarified that the proposed calculation method is useful for predicting the characteristics in a relatively simple way. The air turbo blower impeller has a 15mm diameter and a 3mm thickness with centrifugal suction blades on both faces that were made by precision machining. The measured rotational frequency of the rotor exceeds 350Hz (21,000rpm) in the test. The rotor vibration was verified as a forward whirl with a conical mode. The blower characteristics were also investigated. The maximum discharge air flow rate and the pressure were 19.2×10−5m3/s and 1.77kPa, respectively, at the maximum rotational frequency of 350Hz. This may be used as a small-size air supply blower.

1205 高出力小型空冷ファンの性能特性について(流体力学VII)

1205 高出力小型空冷ファンの性能特性について(流体力学VII)

Effect of frying parameters on crispiness and sound emission of cassava crackers

Cassava crackers, based in cassava starch and water, were produced by deep-fat frying in oil at 140, 150 and 160 °C. Physical properties of cassava crackers were monitored at 5, 10 and 15 s of the frying process, moisture contents, bulk density, linear expansion and penetration forces and sound emission were evaluated. The results showed that with increasing frying (time and temperature), the moisture content, the linear expansion, the number of force and sound peaks significantly increased while the density and maximum and mean of force peaks decreased. Further it could be seen that with higher temperature the number of small size air cells increased. Correlations were found between physical and textural properties and sound emission. Moisture content, bulk density, maximum of sound peak, maximum force and mean force were negatively correlated with linear expansion, number of sound peaks and number of force peaks.

Spectrum controlled supercontinuum generation in microstructure tellurite fibers

We report what we believe to be the first demonstration of flattened supercontinuum (SC) generation from a microstructure tellurite fiber pumped by a tunable ultrafast laser source with a pulse width of 180 fs. When the pump light is launched into 0.574 m long air-cladding tellurite fiber with small size air holes, which are comparable with the core diameter, we obtain flattened SC spectra expanding from 1000 to 2100 nm by tuning the pumping wavelength to the range of 1400-1600 nm.

DEVELOPMENT OF SMALL-SIZED AIR PUMP USING BALLOON VIBRATOR FOR WEARABLE DEVICES

This study is aimed at developing a small-sized air pump using an originally contrived balloon vibrator for wearable devices. The developed pump can compress air by vibrating a balloon vibrator which is composed of a doughnut-shaped balloon diaphragm fitted with a circular stainless steel plate. The balloon diaphragm is filled with air. This pump has characteristics as an oil-free, doesn't leak air at all, and has a longer stroke than existed diaphragm pumps. Therefore, this pump is expected to have higher discharge performance than existed diaphragm pumps. In addition, it is also expected to develop an output variable air pump by controlling the inner pressure of balloon. In this paper, the structure of the developed pump is described, and then the fundamental characteristics of this pump are evaluated.

A parametric study of LES on laminar-turbulent transitional flows past an airfoil

Low-Reynolds-number aerodynamic performance of small-sized air vehicles is an area of increasing interest. In this study, low-Reynolds-number flows past an SD7003 airfoil are investigated to understand important viscous features of laminar separation and transitional flow followed by the complicated behavior of the flow reattachment process. In order to satisfy the three-dimensional (3D) requirement of the code, a simple “3D wing” is constructed from a two-dimensional (2D) airfoil. A parametric study of large eddy simulation (LES) on the airfoil flows at Re = 60,000 is performed. Effects of grid resolution and sub-grid scale (SGS) models are investigated. Although 3D effects cannot be accurately captured owing to the limitation of the grid resolution in the spanwise direction, the preliminary LES calculations do reveal some important flow characteristics such as leading-edge laminar separation and vortex shedding from the primary laminar separation bubble on the low-Reynolds-number airfoil.

Sensitivity of ARGO-YBJ to different composition models in the energy range 10 ÷ 500 TeV

The ARGO-YBJ experiment is currently under construction at the Yangbajing Cosmic Ray Laboratory (4300 m a.s.l.).The detector consists of a central carpet, 74 × 78 m 2 , made of a single layer of Resistive Plate Counters (RPCs), and surrounded by a partially instrumented guard ring for a total instrumented area of about 6700 m 2 . The digital read-out, performed by means of pick-up electrodes 6.7 × 62 cm 2 ( strip ), allows to measure the charged particle number of small size air showers. The technique of counting the number of fired strips on the ARGO carpet corresponds to operate in the 10÷500 TeV energy region where both direct and indirect measurements on the primary cosmic radiation have been performed. Many composition models have been proposed by different experiments. In this work we discuss the ability of the ARGO detector to discriminate among some models.

FPGAs widen the ARGO-YBJ experiment's eyes

The ARGO-YBJ experiment is presently under construction at the Yangbaijing High-Altitude Cosmic Ray Laboratory (4300 m a.s.l), 90 km north to Lhasa (Tibet, People's Republic of China). ARGO will study fundamental issues in cosmic ray and astroparticle physics by detecting small-size air showers. The detector covers 74 /spl times/ 78 m/sup 2/ with single layer resistive plate counters (RPCs), surrounded by a partially instrumented guard ring. The ARGO Data Acquisition System is designed around static random access memory (SRAM)-based field programmable gate arrays (FPGAs), in order to achieve a fully reconfigurable architecture. In this environment, the same hardware platform performs different functions provided by companion FPGAs' configuration files. Control and monitoring software exploits a web browser to deliver commands and perform diagnostic tests on the boards. In this paper, we describe the hardware and the software strategies that allow the ARGO DAQ to benefit from the flexible architecture of in-system reconfigurable FPGAs.

The ARGO-YBJ detector and high energy GRBs

ARGO-YBJ (Astrophysical Radiation with Ground-based Observatory at YangBaJing) is a detector optimized to study small size air showers. It consists of a layer of Resistive Plate Counters (RPCs) covering an area of similar to 6500 m(2) and will be located in the Yangbajing Laboratory (Tibet, China) at 4300 m a.s.l. ARGO-YBJ will be devoted to a wide range of fundamental issues in cosmic rays and astroparticle physics, including in particular gamma-ray astronomy and gamma-ray bursts physics in the range 10 GeV divided by 500 TeV. The sensitivity of ARGO-YBJ to detect high energy GRBs is presented.