Highly aligned PAN nanofiber bundles prepared via a novel Venturi tube high-speed airflow drafting (VAD) method

2021 ◽  
pp. 130383
Author(s):  
Lei Li ◽  
Jingna Su ◽  
Yuanyuan Wang ◽  
Gang Wang ◽  
Zhichao Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Venturi Tube ◽  
Nanofiber Bundles ◽  
Pan Nanofiber

Bubble Breakup Phenomena in a Venturi Tube

2007 ◽  
Author(s):  
A. Fujiwara ◽  
K. Okamoto ◽  
K. Hashiguchi ◽  
J. Peixinho ◽  
S. Takagi ◽  
...  
Keyword(s):  
High Speed ◽  
Bubbly Flow ◽  
Bubble Diameter ◽  
Pressure Change ◽  
Venturi Tube ◽  
Large Bubble ◽  
Breakup Process ◽  
Bubble Behavior ◽  
Bubble Breakup ◽  
Unstable Surface

Microbubble generation techniques have been proposed in former investigations. Here, we study an effective technique using air bubbly flow into a convergent-divergent nozzle (venturi tube). Pressure change in the diverging section induces bubble breakup. The purpose of this study is to clarify the effect of flow velocity at the throat with respect to the bubble breakup process and the bubble behavior in a venturi tube. Relations between generated bubble diameter and bubble breakup process are also described. Using high speed camera for detailed observation of bubble behavior, the following features were obtained. The velocity at the throat is expected to be of the order of the magnitude of the speed of sound of bubbly flow and a drastic bubble expansion and a shrink is induced. Besides, a liquid column appeared after the bubble flowing into the throat, and it grew up to stick to the bubble like in the form of a jet. This jet induced both unstable surface waves and the breakup of a single large bubble into several pieces.

Development of Removal Technology Using Ozone Microbubble With a Venturi Tube

2015 ◽  
Author(s):  
Yoshihiro Arai ◽  
Yutaka Abe ◽  
Akiko Kaneko ◽  
Tetsuya Kanagawa ◽  
Ken Fujimori ◽  
...  
Keyword(s):  
Vortex Structure ◽  
High Speed ◽  
Water Concentration ◽  
Video Camera ◽  
Venturi Tube ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
Removal Technology ◽  
Shaped Nozzle ◽  
Wafer Processing

The removal technology of single-wafer processing using ozone is proposed on photoresist stripping in the semiconductor manufacturing in order not to generate residual sulfate group after stripping. It is revealed that Disk-shaped nozzle proposed by the authors forms a vortex structure between the disks which is considered to cause the reduction of photoresist stripping rate. This study proposes a disk-shaped convex nozzle. In order to investigate the effects on the flow caused by the presence or absence of the convex, visualization using a high-speed video-camera and numerical simulation of the flow between the disks were conducted. Also, the stripping experiments were conducted to investigate the effects on the photoresist stripping rate caused by the presence or absence of the convex. As a result, the vortex structure that was observed in the disk-shaped nozzle has been disappeared in the disk-shaped convex nozzle. In addition, it is revealed that disk-shaped convex nozzle has the higher stripping ability than disk-shaped nozzle in the convex part. Next, as a stripping method that is different from the conventional, we suggest the ozone microbubble with a venturi tube. To obtaining knowledge about the performance of the photoresist stripping with the ozone microbubbles, first, the generation of ozone microbubbles is observed in the venturi tube via a high speed video camera. Next, to clarify the effect of the superficial liquid and gas velocities on the ozone water concentration and the photoresist stripping rate, ozone water concentration measurement and photoresist stripping experiments were conducted. As a result, the ozone water concentration with increasing superficial velocity increase and the remaining photoresist thickness reduce. In addition, compared with the existing study, it is suggested that the superficial liquid and gas velocities and ozone water concentration affect the photoresist stripping rate.

scholarly journals Experimental study on diesel engine exhaust gas recirculation performance and optimum exhaust gas recirculation rate determination method

2019 ◽  
Vol 6 (6) ◽  
pp. 181907 ◽  
Author(s):  
Xiang-huan Zu ◽  
Chuan-lei Yang ◽  
He-Chun Wang ◽  
Yin-yan Wang
Keyword(s):  
Decision Making ◽  
High Pressure ◽  
Diesel Engine ◽  
High Speed ◽  
Performance Test ◽  
Exhaust Gas Recirculation ◽  
Venturi Tube ◽  
Pressure Curve ◽  
Exhaust Gas ◽  
Gas Recirculation

In order to study the exhaust gas recirculation (EGR) performance of marine diesel engines, a venturi high-pressure EGR device was established to overcome the exhaust gas reflow problem based on a certain type of turbocharged diesel engine. The EGR performance test is accomplished and an optimal EGR decision-making optimization method based on grey correlation coefficient modified is proposed. The results show that the venturi tube EGR can basically meet the injection requirements of high-pressure exhaust gas and achieve good results. Through the venturi tube EGR, the NO X emissions reduce significantly with the maximum drop of 30.6%. The explosive pressure in cylinder reduces with the EGR rate increases and the cylinder pressure curve shows a single peak at low-speed conditions and double peaks at high-speed condition. However, the fuel consumption rate, NO X and smoke have been negatively affected. Due to small samples, the traditional evaluation method is difficult to determine the optimal EGR rate reasonably, while the proposed method can effectively solve this problem. It can weaken the shortcomings of subjective judgement and greatly improve the rationality of decision-making results.

Inception and Dynamics of Traveling-Bubble-Type Cavitation in a Venturi

2003 ◽  
Author(s):  
Keiichi Sato ◽  
Kouji Hachino ◽  
Yasuhiro Saito
Keyword(s):  
Tensile Strength ◽  
Count Rate ◽  
High Speed ◽  
Cavitation Number ◽  
Venturi Tube ◽  
Local Pressure ◽  
Cavitation Inception ◽  
Sheet Cavitation ◽  
High Speed Video ◽  
Bubble Cavitation

The inception of cavitation is basically caused by a bubble nucleus which flows into the low pressure region in the liquid flow. Therefore the phenomenon is dependent on the tensile strength or the nuclei concentration of tested water. The cavitation susceptibility of water which controls the cavitation inception point has been made clear though various methods were proposed to measure the nuclei concentration. Cavitation susceptibility meter using a small venturi tube is also one of the methods to measure the nuclei concentration. It is pointed out that this method can be directly related to active nuclei for cavitation inception and gives a useful and simple device to estimate the tensile strength of water. In the present paper, to establish a measurement method of cavitation susceptibility using a venturi tube, the following points are investigated, such as; the relation between the occurrence, count rate of cavitation bubbles and cavitation number, the measurement of positions and local pressure of bubble occurrence and the high-speed video observation of bubble aspects from inception to collapse. As the result, the main points obtained are as follows. A traveling-bubble cavitation appears dominantly in a nozzle-type venturi tube with little possibility of flow separation. Cavitation aspects and the bubble occurrence count rate change with cavitation number and water quality (dissolved gas content). Unstable sheet cavitation can be also observed near the venturi diffuser and at relatively low cavitation number. The various behaviors of traveling bubble cavitation in a venturi are observed from inception to collapse using a high-speed video camera system.

The Observation of Micro-bubble Generation in Venturi Tube by Ultra-high-speed Camera

2003 ◽  
Vol 2003.6 (0) ◽  
pp. 289-290
Author(s):  
Akiko FUJIWARA ◽  
Kazuhiho WATANABE ◽  
Shu TAKAGI ◽  
Yoichiro MATSUMOTO
Keyword(s):  
High Speed ◽  
Venturi Tube ◽  
High Speed Camera ◽  
Bubble Generation ◽  
Ultra High Speed ◽  
Micro Bubble

Study on Bubble Breakup Mechanism in a Venturi Tube

2011 ◽  
Author(s):  
Yasumichi Nomura ◽  
Shin-ichiro Uesawa ◽  
Akiko Kaneko ◽  
Yutaka Abe
Keyword(s):  
Flow Structure ◽  
High Speed ◽  
Pressure Profile ◽  
Venturi Tube ◽  
Pressure Recovery ◽  
Bubble Collapse ◽  
Bubble Behavior ◽  
Low Velocity ◽  
Breakup Mechanism ◽  
Bubble Breakup

Microbubbles are expected to be applied in various subjects such as engineering and medical fields. Thus, on-demand microbubble generation techniques with high efficiently are required. In the present study, the microbubble generator using a venturi tube (converging-diverging nozzle) is focused. Although this technique realizes generation of many tiny bubbles with less than several-hundred-micrometer diameter, there are several unsolved parts of flow structure in a venturi tube on bubble breakup behavior. The purpose of this study is to clarify the bubble breakup mechanism in a venturi tube for practical use. In the present study, using a high speed camera for detailed observation of bubble behavior, the following features were obtained. In low velocity conditions, bubbles are divided in several pieces with a jet penetrating from the top (downstream) to the bottom (upstream) part of the bubble. In high velocity conditions, bubbles collapse in countless microbubbles with a drastic bubble expansion and shrinkage. Also, in order to clarify the flow structure in a venturi tube, pressure profile is measured in detail. Under chocking condition, the pressure profile shows the tendency of supersonic flow in a Laval nozzle and sudden pressure gradient appears in the diverging section. There are strong correlations between bubble fission points and pressure recovery points. It is suggested that bubble collapse is strongly influenced with pressure recovery in the diverging section.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

The on-line use of histogram data for high-speed correction and alignment of electron microscope images

1984 ◽  
Vol 42 ◽  
pp. 556-557
Author(s):  
William Krakow
Keyword(s):  
Power Spectrum ◽  
High Speed ◽  
Direct Memory Access ◽  
Digital Television ◽  
Contrast Transfer Function ◽  
The Past ◽  
High Resolution Tem ◽  
On Line ◽  
Correction Of Astigmatism ◽  
The Fourier Transform

In the past few years on-line digital television frame store devices coupled to computers have been employed to attempt to measure the microscope parameters of defocus and astigmatism. The ultimate goal of such tasks is to fully adjust the operating parameters of the microscope and obtain an optimum image for viewing in terms of its information content. The initial approach to this problem, for high resolution TEM imaging, was to obtain the power spectrum from the Fourier transform of an image, find the contrast transfer function oscillation maxima, and subsequently correct the image. This technique requires a fast computer, a direct memory access device and even an array processor to accomplish these tasks on limited size arrays in a few seconds per image. It is not clear that the power spectrum could be used for more than defocus correction since the correction of astigmatism is a formidable problem of pattern recognition.

Structural changes in silicon-on-insulator material during post-implantation annealing

1986 ◽  
Vol 44 ◽  
pp. 736-737
Author(s):  
C. O. Jung ◽  
S. J. Krause ◽  
S.R. Wilson
Keyword(s):  
Integrated Circuits ◽  
Oxide Layer ◽  
High Speed ◽  
Structural Changes ◽  
Device Fabrication ◽  
Silicon On Insulator ◽  
High Quality ◽  
Radiation Hardened ◽  
Post Implantation ◽  
Very High

Silicon-on-insulator (SOI) structures have excellent potential for future use in radiation hardened and high speed integrated circuits. For device fabrication in SOI material a high quality superficial Si layer above a buried oxide layer is required. Recently, Celler et al. reported that post-implantation annealing of oxygen implanted SOI at very high temperatures would eliminate virtually all defects and precipiates in the superficial Si layer. In this work we are reporting on the effect of three different post implantation annealing cycles on the structure of oxygen implanted SOI samples which were implanted under the same conditions.

Sign in / Sign up

Export Citation Format

Share Document