Influence of Suction Nozzle Shape on Measured Particle Concentration due to Anisokinetic Sampling.

1998 ◽  
Vol 24 (2) ◽  
pp. 299-305
Author(s):  
MITSUO SAMATA ◽  
CHIKAO KANAOKA
Keyword(s):  
Particle Concentration ◽  
Nozzle Shape ◽  
Suction Nozzle ◽  
Measured Particle

Isolation Ratio and Particle Performance Measurement of a SMIF System

1997 ◽  
Vol 40 (6) ◽  
pp. 23-28
Author(s):  
Benjamin Liu ◽  
Seong-Ho Yoo
Keyword(s):  
Performance Evaluation ◽  
Particle Concentration ◽  
Experimental System ◽  
The Other ◽  
High Isolation ◽  
System A ◽  
Interface System ◽  
Self Powered ◽  
Test Atmosphere ◽  
Measured Particle

This paper discusses the performance evaluation of a SMIF (Standard Mechanical Interface) system. A two-chamber experimental system is used with one chamber providing the test atmosphere of the cleanroom and the other providing the test atmosphere of the minienvironment. The cleanroom atmospher can be varied by adjusting the amount of particles injected into the chamber. Particle concentration ranges from 1,000/ft-3 to 10 million/ft3 can be created in the chamber to simulate different cleanroom conditions. The atmosphere of the second chamber is maintained at Class I or better equivalent by means of a self-powered ultra-low penetration air (ULPA) filter blower unit. By means of this system, the ability of the SMIF system to isolate the contaminants in the cleanroom atmosphere from the minienvironment atmosphere was measured. In addition, the particles added to the wafer during wafer cassette handling by the SMIF-Arm were also measured by a wafer scanner. The results indicate that the SMIF system tested is capable of providing extremely high isolation ratios in terms of its ability to isolate the cleanroom atmosphere from the atmosphere of the minienvironment. Isolation ratios in excess of 1 million to 1 or better have been measured. The measured particle per wafer per pass (PWP) numbers were generally around 0.02 or less for most wafers, with the average at 0.0118.

scholarly journals Microdebrider is less aerosol-generating than CO2 laser and cold instruments in microlaryngoscopy

2021 ◽  
Author(s):  
Enni Sanmark ◽  
Lotta-Maria A. H. Oksanen ◽  
Noora Rantanen ◽  
Mari Lahelma ◽  
Veli-Jukka Anttila ◽  
...  
Keyword(s):  
High Risk ◽  
Surgical Procedures ◽  
Particle Concentration ◽  
Aerosol Particles ◽  
Aerosol Generation ◽  
Laryngeal Surgery ◽  
Step Down ◽  
Particle Sizer ◽  
Measured Particle ◽  
Cold Dissection

Abstract Objective COVID-19 spreads through aerosols produced in coughing, talking, exhalation, and also in some surgical procedures. Use of CO2 laser in laryngeal surgery has been observed to generate aerosols, however, other techniques, such cold dissection and microdebrider, have not been sufficiently investigated. We aimed to assess whether aerosol generation occurs during laryngeal operations and the effect of different instruments on aerosol production. Methods We measured particle concentration generated during surgeries with an Optical Particle Sizer. Cough data collected from volunteers and aerosol concentration of an empty operating room served as references. Aerosol concentrations when using different techniques and equipment were compared with references as well as with each other. Results Thirteen laryngological surgeries were evaluated. The highest total aerosol concentrations were observed when using CO2 laser and these were significantly higher than the concentrations when using microdebrider or cold dissection (p < 0.0001, p < 0.0001) or in the background or during coughing (p < 0.0001, p < 0.0001). In contrast, neither microdebrider nor cold dissection produced significant concentrations of aerosol compared with coughing (p = 0.146, p = 0.753). In comparing all three techniques, microdebrider produced the least aerosol particles. Conclusions Microdebrider and cold dissection can be regarded as aerosol-generating relative to background reference concentrations, but they should not be considered as high-risk aerosol-generating procedures, as the concentrations are low and do not exceed those of coughing. A step-down algorithm from CO2 laser to cold instruments and microdebrider is recommended to lower the risk of airborne infections among medical staff.

scholarly journals Size- and Time-Dependent Aerosol Removal from a Protective Box during Simulated Intubation and Extubation Procedures

COVID ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 315-324
Author(s):  
Luka Pirker ◽  
Metod Čebašek ◽  
Matej Serdinšek ◽  
Maja Remškar
Keyword(s):  
Particle Size ◽  
Particle Concentration ◽  
Time Frame ◽  
Time Dependent ◽  
Medical Professionals ◽  
Particle Sizes ◽  
Background Levels ◽  
Aerosol Generator ◽  
Plastic Bag ◽  
Measured Particle

Because the SARS-CoV-2 virus primarily spreads through droplets and aerosols, a protective box could provide adequate protection by shielding medical professionals during the intubation and extubation procedures from generated droplets and aerosols. In this study, size- and time-dependent aerosol concentrations were measured inside and outside the protective box in the particle size ranging from 14 nm to 20 μm during simulated intubation and extubation procedures. An improved protective box with active ventilation was designed based on a plastic bag with armholes covered with latex sheets that utilizes a supportive frame. Coughing during the intubation and extubation procedure was simulated using an aerosol generator which dispersed the aerosol powder into the protective box. During the intubation and extubation procedure, the concentration of particles increased inside the protective box but, due to the high negative airflow, quickly dropped to background levels. The particle concentration of all measured particle sizes decreased within the same time frame. No leakage of particles was observed through the armhole openings. The presented protective box design provides excellent protection against generated droplets and aerosols. The decrease in concentration does not depend on the particle size. Outside the box, particle concentration did not change with time.

scholarly journals Thermodynamic correction of particle concentrations measured by underwing probes on fast flying aircraft

2015 ◽  
Vol 8 (12) ◽  
pp. 13423-13469 ◽  
Author(s):  
R. Weigel ◽  
P. Spichtinger ◽  
C. Mahnke ◽  
M. Klingebiel ◽  
A. Afchine ◽  
...  
Keyword(s):  
Particle Concentration ◽  
Sample Volume ◽  
Ambient Conditions ◽  
Speed Sensor ◽  
Particle Penetration ◽  
Research Aircraft ◽  
Air Sample ◽  
Air Speed ◽  
Particle Imaging ◽  
Measured Particle

Abstract. Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable for different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the particle penetration speed through the instruments' detection area equals the aircraft speed (True Air Speed, TAS). However, particle imaging instruments equipped with pitot-tubes measuring the Probe Air Speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO – High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation the corresponding concentration correction factor ξ is applicable to the high frequency measurements of each underwing probe which is equipped with its own air speed sensor (e.g. a pitot-tube). ξ-values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 260 m s−1. From HALO data it is found that ξ does not significantly vary between the different deployed instruments. Thus, for the current HALO underwing probe configuration a parameterisation of ξ as a function of TAS is provided for instances if PAS measurements are lacking. The ξ-correction yields higher ambient particle concentration by about 15–25 % compared to conventional procedures – an improvement which can be considered as significant for many research applications. The calculated ξ-values are specifically related to the considered HALO underwing probe arrangement and may differ for other aircraft or instrument geometries. Moreover, the ξ-correction may not cover all impacts originating from high flight velocities and from interferences between the instruments and, e.g., the aircraft wings and/or fuselage. Consequently, it is important that PAS (as a function of TAS) is individually measured by each probe deployed underneath the wings of a fast-flying aircraft.

scholarly journals Thermodynamic correction of particle concentrations measured by underwing probes on fast-flying aircraft

2016 ◽  
Vol 9 (10) ◽  
pp. 5135-5162 ◽  
Author(s):  
Ralf Weigel ◽  
Peter Spichtinger ◽  
Christoph Mahnke ◽  
Marcus Klingebiel ◽  
Armin Afchine ◽  
...  
Keyword(s):  
Correction Factor ◽  
Particle Concentration ◽  
Sample Volume ◽  
Time Interval ◽  
Ambient Conditions ◽  
Measured Concentration ◽  
Air Sample ◽  
Cloud Particles ◽  
Air Speed ◽  
Measured Particle

Abstract. Particle concentration measurements with underwing probes on aircraft are impacted by air compression upstream of the instrument body as a function of flight velocity. In particular, for fast-flying aircraft the necessity arises to account for compression of the air sample volume. Hence, a correction procedure is needed to invert measured particle number concentrations to ambient conditions that is commonly applicable to different instruments to gain comparable results. In the compression region where the detection of particles occurs (i.e. under factual measurement conditions), pressure and temperature of the air sample are increased compared to ambient (undisturbed) conditions in certain distance away from the aircraft. Conventional procedures for scaling the measured number densities to ambient conditions presume that the air volume probed per time interval is determined by the aircraft speed (true air speed, TAS). However, particle imaging instruments equipped with pitot tubes measuring the probe air speed (PAS) of each underwing probe reveal PAS values systematically below those of the TAS. We conclude that the deviation between PAS and TAS is mainly caused by the compression of the probed air sample. From measurements during two missions in 2014 with the German Gulfstream G-550 (HALO – High Altitude LOng range) research aircraft we develop a procedure to correct the measured particle concentration to ambient conditions using a thermodynamic approach. With the provided equation, the corresponding concentration correction factor ξ is applicable to the high-frequency measurements of the underwing probes, each of which is equipped with its own air speed sensor (e.g. a pitot tube). ξ values of 1 to 0.85 are calculated for air speeds (i.e. TAS) between 60 and 250 m s−1. For different instruments at individual wing position the calculated ξ values exhibit strong consistency, which allows for a parameterisation of ξ as a function of TAS for the current HALO underwing probe configuration. The ability of cloud particles to adopt changes of air speed between ambient and measurement conditions depends on the cloud particles' inertia as a function of particle size (diameter Dp). The suggested inertia correction factor μ (Dp) for liquid cloud drops ranges between 1 (for Dp < 70 µm) and 0.8 (for 100 µm < Dp < 225 µm) but it needs to be applied carefully with respect to the particles' phase and nature. The correction of measured concentration by both factors, ξ and μ (Dp), yields higher ambient particle concentration by about 10–25 % compared to conventional procedures – an improvement which can be considered as significant for many research applications. The calculated ξ values are specifically related to the considered HALO underwing probe arrangement and may differ for other aircraft. Moreover, suggested corrections may not cover all impacts originating from high flight velocities and from interferences between the instruments and e.g. the aircraft wings and/or fuselage. Consequently, it is important that PAS (as a function of TAS) is individually measured by each probe deployed underneath the wings of a fast-flying aircraft.

scholarly journals A global view on atmospheric concentrations of sub-3 nm particles measured with the Particle Size Magnifier

2016 ◽  
Author(s):  
Jenni Kontkanen ◽  
Katrianne Lehtipalo ◽  
Lauri Ahonen ◽  
Juha Kangasluoma ◽  
Hanna Manninen ◽  
...  
Keyword(s):  
Particle Size ◽  
Boreal Forest ◽  
Particle Concentration ◽  
Aerosol Particles ◽  
Subsequent Growth ◽  
Neutral Particles ◽  
Global View ◽  
Atmospheric Concentrations ◽  
Different Sources ◽  
Measured Particle

Abstract. The measurement of sub-3 nm aerosol particles is technically challenging. Therefore, there is a lack of knowledge about the concentrations of atmospheric sub-3 nm particles and their variation in different environments. In this study, the concentrations of ~ 1–3 nm particles measured with a Particle Size Magnifier (PSM) were investigated at nine sites around the world. Sub-3 nm particle concentrations were highest at the sites with strong anthropogenic influence. In boreal forest measured particle concentrations were clearly higher in summer than in winter, suggesting the importance of biogenic precursor vapors in this environment. At all sites sub-3 nm particle concentration had daytime maxima, which are likely linked to the photochemical production of precursor vapors and the emissions of precursor vapors or particles from different sources. When comparing ion concentrations to the total sub-3 nm particle concentrations, electrically neutral particles were observed to dominate in polluted environments and in boreal forest during spring and summer. Generally, the concentrations of sub-3 nm particles seem to be determined by the availability of precursor vapors rather than the level of the sink caused by pre-existing aerosol particles. The results also indicate that the formation of the smallest particles and their subsequent growth to larger sizes are two separate processes, and therefore studying the concentration of sub-3 nm particles separately in different size ranges is essential.

scholarly journals Dispersion of a Traffic Related Nanocluster Aerosol Near a Major Road

Atmosphere ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 309 ◽  
Author(s):  
Oskari Kangasniemi ◽  
Heino Kuuluvainen ◽  
Joni Heikkilä ◽  
Liisa Pirjola ◽  
Jarkko V. Niemi ◽  
...  
Keyword(s):  
Particle Concentration ◽  
Size Range ◽  
Urban Environments ◽  
Main Process ◽  
Particle Population ◽  
Total Particle ◽  
Modelling Studies ◽  
Ultrafine Aerosol ◽  
Transformation Processes ◽  
Measured Particle

Traffic is a major source of ultrafine aerosol particles in urban environments. Recent studies show that a significant fraction of traffic-related particles are only few nanometers in diameter. Here, we study the dispersion of this nanocluster aerosol (NCA) in the size range 1.3–4 nm. We measured particle concentrations near a major highway in the Helsinki region of Finland, varying the distance from the highway. Additionally, modelling studies were performed to gain further information on how different transformation processes affect NCA dispersion. The roadside measurements showed that NCA concentrations fell more rapidly than the total particle concentrations, especially during the morning. However, a significant amount of NCA particles remained as the aerosol population evolved. Modelling studies showed that, while dilution is the main process acting on the total particle concentration, deposition also had a significant impact. Condensation and possibly enhanced deposition of NCA were the main plausible processes explaining why dispersion is faster for NCA than for total particle concentration, while the effect of coagulation on all size ranges was small. Based on our results, we conclude that NCA may play a significant role in urban environments, since, rather than being scavenged by larger particles, NCA particles remain in the particle population and grow by condensation.

Multi-criteria optimization of the four-finger gripper mechanism

2020 ◽  
Vol 8 (4) ◽  
pp. 276-286
Author(s):  
Vu Duc Quyen ◽  
Andrey Ronzhin
Keyword(s):  
Multicriteria Optimization ◽  
Kinematic Model ◽  
Objective Functions ◽  
Nsga Ii ◽  
Suction Nozzle

Three posterior algorithms NSGA-II, MOGWO and MOPSO to solve the problem of multicriteria optimization of the robotic gripper design are considered. The description of the kinematic model of the developed prototype of the four-fingered gripper for picking tomatoes, its limitations and objective functions used in the optimization of the design are given. The main advantage of the developed prototype is the use of one actuator for the control of the fingers and the suction nozzle. The results of optimization of the kinematic model and the dimensions of the elements of robotic gripper using the considered posterior algorithms are presented.

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