scholarly journals Analysis and evaluation of drop point for water jet based on wave model

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Yang Qu ◽  
◽  
Xintian Liu ◽  
Minghui Zhang ◽  
Yansong Wang ◽  
...  
Keyword(s):  
Wave Model ◽  
Water Jet ◽  
Cross Sectional ◽  
Analysis And Evaluation ◽  
Fire Extinguishing ◽  
Quadratic Drag ◽  
Jet Breakup ◽  
Jet Trajectory ◽  
Air Resistance ◽  
Breakup Model

To study the precision of the fire water monitor with important influence on fire extinguishing effect, the drop point of fire water monitor is studied. The quadratic drag model is selected on the basis of the analysis of the mechanical model of the fluidic microbody, considering the change of the cross-sectional area caused by velocity and breakup of the water jet. The boundary between breakup and atomization is clarified, and the change of diameter and area of the droplet is also discussed based on the theory of liquid jet breakup, to build a dynamic breakup model of air resistance and broken jet. The jet trajectory of the fire water monitor is mainly influenced by the initial velocity, pitching angle, air resistance, and other factors. In this paper, the influence of different parameters on the jet drop point is considered. The analysis and comparison of all the points are performed, and the range of uncertainty is obtained. Finally, the accurate prediction of the jet trajectory is analyzed.

An Empirical Shaped Charge Jet Breakup Model

2014 ◽  
Author(s):  
Ernest L. Baker ◽  
James Pham ◽  
Tan Vuong
Keyword(s):  
Shaped Charge ◽  
Jet Breakup ◽  
Shaped Charge Jet ◽  
Breakup Model

Disaster Risk Assessment Among Iranian Exceptional Schools

2021 ◽  
pp. 1-5
Author(s):  
Seyedeh Samaneh Miresmaeeli ◽  
Nafiseh Esmaeili ◽  
Sepideh Sadeghi Ashlaghi ◽  
Zahra Abbasi Dolatabadi
Keyword(s):  
Risk Assessment ◽  
Cross Sectional Study ◽  
Disaster Risk ◽  
Disaster Mitigation ◽  
Vulnerable Groups ◽  
Risk Level ◽  
Cross Sectional ◽  
Fire Extinguishing ◽  
Disaster Risk Assessment ◽  
The Right

Abstract Background: Exceptional children, like other children, have the right to be educated in a safe environment. Disasters are considered as serious issues regarding safety and security of educational environments. Following disasters, vulnerable groups, especially children with handicaps and disabilities are more likely to be seriously injured. Thus, the present study aimed to evaluate the safety and disaster risk assessment of exceptional schools in Tehran, Iran. Method: The cross-sectional study was conducted in exceptional schools in Tehran, 2018. First, 55 exceptional schools in all grades were selected based on census sampling method and evaluated by using a checklist designed by Tehran Disaster Mitigation and Management Organization (TDMMO) and Ministry of Education in 2015. The data were analyzed using Excel software and statistical descriptive tests. Result: Based on the results, school facilities are worn and have unsafe elevators (least safety: 7.69%), yards (least safety: 9.52%), laboratories (least safety: 16.67%), libraries (least safety: 24.24%), fire extinguishing systems (least safety: 28.99%), and storage rooms and kitchens (least safety: 33.33%) which require immediate considerations. In total, the safety of exceptional schools in this study was 70.13%, which suggests medium-risk level. Conclusion: The educational settings must be reconsidered, along with identifying the risk and safety at school. In addition, a standard should be established for evaluating safety, especially in exceptional schools.

LINGUAL BRAKE ANALYSIS AND EVALUATION IN CHILDREN IN THE AMAZON FACULTY - IAES

2021 ◽  
pp. 10-11
Author(s):  
Darlemcris da Fonseca Vieira ◽  
Anselmo Junio Pedroso Matos
Keyword(s):  
Statistical Data ◽  
Complete Removal ◽  
Pediatric Dentistry ◽  
Surgical Removal ◽  
Cross Sectional ◽  
Analysis And Evaluation ◽  
Speech Therapist ◽  
Data Program ◽  
Adipose Cells ◽  
Important Structure

The lingual brake is an important structure for the musculoskeletal growth of the baby's jaws, inuencing the act of sucking, speaking and feeding. There is an alteration called ankyloglossia (Ankylos: Linked and Glossa: Tongue), dened as a congenital malformation that alters mobility and lingual function. Brake change occurs when a portion of the tissue that should have suffered apoptosis during embryonic development remains on the underside of the tongue, restricting its movement. The lingual brake is formed by a connective tissue rich in elastic bers, lined with nonkeratinized stratied paved epithelium, containing adipose cells, muscle bers and blood vessels. Any anatomical or functional brake deciency can have an impact on functions based on their severity. Its diagnosis is not difcult, as it is very visible and can be done through the "Tongue Test". Surgical removal of the brake is necessary when it causes gingival retraction, diastema, hindering orthodontic, speech therapist, prosthetic and aesthetic treatment. It is advisable to wait for the individual's growth process, especially between 6 months and 6 years of life. The treatment performed for this anomaly is the frenectomy, which consists in the complete removal of the brake insert. The objective of the present study was to conduct a research that evaluated the lingual brake of children, and the need for surgical treatment at the pediatric dentistry clinic at Amazon Faculty - IAES through a questionnaire. It was a cross-sectional, descriptive and observational study, which evaluated the lingual brake of children. Data were analyzed quantitatively and qualitatively using the statistical data program. The software used for data analysis was Epi Info version 7.2.2.6 for windows. It was concluded that of the 50 lingual brakes evaluated, 14% presented alteration, with a preference for females. It was clear the need for an early diagnosis, besides the need for a multidisciplinary team

scholarly journals Geometry of the Vocal Tract and Properties of Phonation near Threshold: Calculations and Measurements

2019 ◽  
Vol 9 (13) ◽  
pp. 2755 ◽  
Author(s):  
Lewis Fulcher ◽  
Alexander Lodermeyer ◽  
George Kähler ◽  
Stefan Becker ◽  
Stefan Kniesburges
Keyword(s):  
Vocal Tract ◽  
Wave Model ◽  
Vocal Folds ◽  
Cross Sectional Area ◽  
Inertial Effects ◽  
Sectional Area ◽  
Cross Sectional ◽  
Physical Mechanisms ◽  
Lumped Element ◽  
Geometrical Boundary

In voice research, analytically-based models are efficient tools to investigate the basic physical mechanisms of phonation. Calculations based on lumped element models describe the effects of the air in the vocal tract upon threshold pressure (Pth) by its inertance. The latter depends on the geometrical boundary conditions prescribed by the vocal tract length (directly) and its cross-sectional area (inversely). Using Titze’s surface wave model (SWM) to account for the properties of the vocal folds, the influence of the vocal tract inertia is examined by two sets of calculations in combination with experiments that apply silicone-based vocal folds. In the first set, a vocal tract is constructed whose cross-sectional area is adjustable from 2.7 cm2 to 11.7 cm2. In the second set, the length of the vocal tract is varied from 4.0 cm to 59.0 cm. For both sets, the pressure and frequency data are collected and compared with calculations based on the SWM. In most cases, the measurements support the calculations; hence, the model is suited to describe and predict basic mechanisms of phonation and the inertial effects caused by a vocal tract.

Generation of Surfaces with Isotropic and Anisotropic Wetting Properties by Curved Water Jet Guided Laser Micro-Machining

2020 ◽  
Author(s):  
Yi Shi ◽  
Jian Cao ◽  
Kornel Ehmann
Keyword(s):  
Water Jet ◽  
Nanosecond Laser ◽  
Micro Machining ◽  
Metallic Surfaces ◽  
Wetting Properties ◽  
Laser Micro Machining ◽  
Jet Trajectory ◽  
Wide Range ◽  
Secondary Motion ◽  
Motion Speed

Abstract This experimental work utilizes a newly developed method, curved water jet guided laser micro-machining, to generate micro features on metallic surfaces. During the process, material is removed by a high-power nanosecond laser beam which is transmitted through a high-pressure micro water jet via total internal reflection. To achieve intricate texturing patterns, a secondary motion component is superimposed on the XY motion of the workpiece provided by the motion stage. The secondary motion is generated by deflecting the water jet trajectory by a controllable dielectrophoretic force. The induced secondary motion of the water jet cuts the processing time to one half when generating texture patterns for isotropic wetting as compared to processes with only XY motion. The ability to alter the water jet's trajectory by tens of microns at high frequencies, which is beyond the capability of conventional CNC machines, allows a wide range of different micro patterns to be generated, profoundly increasing the flexibility and efficiency of the process as compared to conventional approaches. As a demonstration, surface textures for isotropic and anisotropic behaviors are generated on stainless steel surfaces. The influence of feature spacing, motion speed (frequency) and texturing patterns on surface wettability are studied.

Objective assessment of nasal resistance in patients with nasal disease

2003 ◽  
Vol 117 (8) ◽  
pp. 609-613 ◽  
Author(s):  
A. H. Suzina ◽  
M. Hamzah ◽  
A. R. Samsudin
Keyword(s):  
Nasal Obstruction ◽  
Objective Assessment ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Subjective Complaint ◽  
Air Resistance ◽  
Significant Difference ◽  
Nasal Disease ◽  
The Mean ◽  
Active Anterior Rhinomanometry

Nasal obstruction is a subjective complaint in patients with nasal disease.The ability to quantitate the nasal ventilation dysfunction would be useful for making the appropriate choice of nasal disease management. This cross-sectional study comprised of 200 adult subjects. They underwent assessment of relevant symptoms, nasal examination and investigations before undergoing active anterior rhinomanometry (AAR) assessment. A group of 88 normal subjectsand 112 patients with nasal disease were included. The mean total nasal air resistance (NAR) was significantly higher in patients with nasal disease (0.33 Pa/cm3/s) as compared tonormal subjects (0.24 Pa/cm3/s). There was no significant difference in total NAR between patients with symptoms of nasal obstruction and those without the symptoms (p = 0.42). It is concluded that AAR is a sensitive but not a specific tool for the detection of abnormalities in NAR and it failed to relate to the symptom of nasal obstruction.

Coupled Simulations of Nozzle Flow, Primary Fuel Jet Breakup, and Spray Formation

2004 ◽  
Vol 127 (4) ◽  
pp. 897-908 ◽  
Author(s):  
Eberhard von Berg ◽  
Wilfried Edelbauer ◽  
Ales Alajbegovic ◽  
Reinhard Tatschl ◽  
Martin Volmajer ◽  
...  
Keyword(s):  
Fluid Model ◽  
Liquid Core ◽  
Nozzle Flow ◽  
Nozzle Orifice ◽  
Spray Formation ◽  
Jet Breakup ◽  
Fuel Jet ◽  
Primary Breakup ◽  
Two Fluid Model ◽  
Breakup Model

Presented are two approaches for coupled simulations of the injector flow with spray formation. In the first approach the two-fluid model is used within the injector for the cavitating flow. A primary breakup model is then applied at the nozzle orifice where it is coupled with the standard discrete droplet model. In the second approach the Eulerian multi-fluid model is applied for both the nozzle and spray regions. The developed primary breakup model, used in both approaches, is based on locally resolved properties of the cavitating nozzle flow across the orifice cross section. The model provides the initial droplet size and velocity distribution for the droplet parcels released from the surface of a coherent liquid core. The major feature of the predictions obtained with the model is a remarkable asymmetry of the spray. This asymmetry is in agreement with the recent observations at Chalmers University where they performed experiments using a transparent model scaled-up injector. The described model has been implemented into AVL FIRE computational fluid dynamics code which was used to obtain all the presented results.

scholarly journals Motion Control System Design for a Flying-Type Firefighting System with Water Jet Actuators

Actuators ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 275
Author(s):  
Dong-Hun Lee ◽  
Thinh Huynh ◽  
Young-Bok Kim ◽  
Chakir Soumayya
Keyword(s):  
Control System ◽  
Sliding Mode ◽  
Water Jet ◽  
Related Information ◽  
Fire Extinguishing ◽  
Hazardous Environments ◽  
Pilot Model ◽  
Actuation System ◽  
Fire Accidents ◽  
Fire Extinguishing System

This paper presents the design and modeling of a flying-type fire extinguishing system. Fire accidents present very hazardous environments, and firefighters are in danger of losing their lives while putting out the fire. Strict safety measures should be considered to guarantee safe working conditions for firefighters, which is not the case every time, as fatalities and casualties are still being recorded. For this reason, a novel fire extinguishing system is proposed to provide more safe firefighting and survivor searches. The system studied in this paper is a pilot model that consists of a water jet-based actuation system to control the flying motion of the robot. The dynamic model of this flying robot is derived using the actuation forces, water jet system characteristics, and related information. The mathematical system model is detailed, a sliding-mode control system and a proportional-integral-derivative controller are designed, and comparative simulation tests are carried out.

scholarly journals Conditional damped random surface velocity model of turbulent jet breakup

2018 ◽  
Author(s):  
Ben Trettel
Keyword(s):  
Free Surface ◽  
Experimental Studies ◽  
Velocity Model ◽  
Turbulent Jet ◽  
Surface Velocity ◽  
Spray Angle ◽  
Random Surface ◽  
Jet Breakup ◽  
Kolmogorov Scale ◽  
Breakup Model

A turbulent jet breakup model is derived using concepts from probability theory. Velocity fluctuations at the free surface are hypothesized to be the cause of turbulent jet breakup. We formalize this idea by treating the fluctuations as random variables, subject to damping from the free surface. In contrast to previous theories, we use a conditional ensemble average to determine quantities of interest because not all fluctuations produce droplets. An energy balance and a closure model are used to determine the Sauter mean diameter. Similar approaches are used to determine the breakup onset location, breakup length, and spray angle. A criteria for the transition to the turbulent atomization regime is derived under the hypothesis that the cause is a change in the minimum velocity from the Hinze scale to the Kolmogorov scale. To validate the model, we compiled data from previous experimental studies using long pipe nozzles. The little data for rough pipes was used to include turbulence intensity in our study.

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