Interactions Between Self and Parametrically Excited Motions in Articulated Tubes

1984 ◽  
Vol 51 (2) ◽  
pp. 423-429 ◽  
Author(s):  
A. K. Bajaj
Keyword(s):  
Nonlinear Dynamics ◽  
Hopf Bifurcation ◽  
Parametric Resonance ◽  
Flow Rate ◽  
Critical Value ◽  
Mean Value ◽  
Vertical Position ◽  
Linearized System ◽  
The Mean ◽  
Stable Solutions

The nonlinear dynamics of a two-segment articulated tubes system conveying a fluid is studied when the flow is harmonically perturbed. The mean value of the flow rate is near its critical value when the downward vertical position gets unstable and undergoes Hopf bifurcation into periodic solutions. The harmonic perturbations are assumed to be in parametric resonance with the linearized system. The method of Alternate Problems is used to obtain the small nonlinear subharmonic solutions of the system. It is shown that, in addition to the usual jump response, the system also exhibits stable and unstable isolated solution branches. For some parameter combinations the stable solutions can become unstable and can then bifurcate into aperiodic or amplitude-modulated motions.

Parameters Dependence of Fibers Diameter and Pores Area in Electrospinning

2018 ◽  
Vol 26 ◽  
pp. 67-73 ◽  
Author(s):  
Emilija Zdraveva ◽  
Budimir Mijovic
Keyword(s):  
Flow Rate ◽  
Polyethylene Oxide ◽  
Volume Flow Rate ◽  
Processing Parameters ◽  
Critical Value ◽  
Volume Flow ◽  
Production Technique ◽  
The World ◽  
The Mean ◽  
Two Parameters

Electrospinning has become the most popular nanofibers production technique that many scientists around the world were intrigued by. It is based on electrostatic forces stretching a polymer solution that undergoes bending instability and eventually results in number of fine nanoscaled filaments. The study reports of four processing parameters effect on electrospun polyethylene oxide (PEO) fibers diameter and pores area. Fibers diameter increase results from the increase of time, volume flow rate and tip to collector distance with a critical value of the first two parameters. The pores area showed both decrease and increase after a critical value of the electrical voltage at 19 kV, while the mean pores area decreased with the time increase. Irregular trends of increasing and decreasing trends of the means pores area were noticed with the change of the volume flow rate and tip to collector distance..

scholarly journals Basal-flow characteristics of a linear medium sliding frictionless over small bedrock undulations

1997 ◽  
Vol 43 (143) ◽  
pp. 71-79 ◽  
Author(s):  
G. Hilmar Gudmundsson
Keyword(s):  
Flow Characteristics ◽  
Local Maximum ◽  
Critical Value ◽  
Two Dimensions ◽  
Creeping Flow ◽  
Wave Number ◽  
Vertical Position ◽  
Gravity Driven ◽  
The Mean ◽  
Basal Flow

AbstractThe basal deformation of a gravity-driven linear creeping flow sliding frictionless over slowly varying bed undulations in two dimensions is analysed analytically, using results from second-order perturbation theory. One of the key results is that, close to sinusoidal bedrock undulations, up to two different spatial regions of local extrusion flow may arise. The offset and onset of extrusion flow is controlled primarily by the amplitude-to-wavelength ratio. Above the crest of a sinusoidal bed line, a local maximum of the surface-parallel velocity develops for ε : =ak< 0.138, whereais the amplitude andkis the wave number. Asεincreases from zerо to this critical value, the vertical position of the velocity maximum moves fromkz= 1 tokz≈ 1.98, wherezis the vertical distance above the mean bed line. Within and above the trough of a sinusoid, a region of local minimum of the surface-parallel velocity component develops, which shifts fromkz= 1 towards the bed line asεincreases front zero to 1/2. Below this velocity minimum, and for some distance above the velocity maximum, the surface-parallel velocity increases with depth. This type of extrusion flow will cause a reversal of borehole-inclination profiles close to the bedrock.

scholarly journals Correlation between results of functional lordosis test and digital pelvic inclinometer

2019 ◽  
Vol 17 (3) ◽  
pp. 247-252
Author(s):  
K. Kolev ◽  
R. Tasheva
Keyword(s):  
Lumbar Lordosis ◽  
Preliminary Investigation ◽  
Critical Value ◽  
Test Methods ◽  
Mean Value ◽  
Functional Test ◽  
Healthy Children ◽  
Pelvic Inclination ◽  
The Mean ◽  
The Difference

THE AIM of this study is to precise the diagnostics of lumbar lordosis in children at primary classes through applying the Digital Pelvic Inclinometer and to correlate the results with the Functional Test. METHODS. The screening examination involved 132 children with the average age 8, 7 from the beginning classes in Sofia. The lumbar lordosis was assessed through the Fuctional Test in all children during the period April - June 2016.. The DPI was applied for preliminary investigation in 25 children of measuring left and rigth pelvic inclination and therefore – torsion. RESULTS. The lordosis test is negative in 8 children and 16 are with functional lordosis. The mean value of the test with DPI - left sided, for healthy children is 7.1 degrees, and in children with functional lordosis is 10.90. The difference of 3.80 is statistically significant due to the value of T-Student criterion (t) of 2.63 at a critical value of 2.07. CONCLUSION. The results showed the correlation between the Digital Pelvic Inclinometer Test and the Functional Lordosis Test. Тhis study confirmed that the applying of the Digital Pelvic Inclinometer give an opportunity to precise the diagnostics of lumbar lordosis in children.

Delay-Induced Bifurcation in High-Order Fractional Goodwin Models with Disparate Orders

2019 ◽  
Vol 29 (07) ◽  
pp. 1950090 ◽  
Author(s):  
Lingzhi Zhao ◽  
Chengdai Huang ◽  
Jinde Cao ◽  
Min Xiao
Keyword(s):  
Hopf Bifurcation ◽  
Time Delays ◽  
Critical Value ◽  
High Order ◽  
High Dimensional ◽  
Bifurcation Parameter ◽  
Characteristic Roots ◽  
Goodwin Model ◽  
Linearized System

In the present paper, we first attempt to investigate the bifurcation for the delayed high-dimensional fractional Goodwin model with different orders. By taking the sum of time delays as a bifurcation parameter, the distribution of the characteristic roots of the linearized system is analyzed and the conditions of Hopf bifurcation are obtained. It is revealed that the model undergoes the Hopf bifurcation when the bifurcation parameter increases and exceeds the critical value. To verify the efficiency of our analytic findings, two simulation examples have been ultimately provided.

Comparison of Inhaled Metaproterenol via Metered-dose and Hand-held Nebulization in Prehospital Treatment of Bronchospasm

1996 ◽  
Vol 11 (4) ◽  
pp. 280-284 ◽  
Author(s):  
Steven J. Rottman ◽  
Nancy E. Robinson ◽  
Marvin L. Birnbaum
Keyword(s):  
Peak Expiratory Flow ◽  
Flow Rate ◽  
Peak Expiratory Flow Rate ◽  
Fire Department ◽  
Mean Value ◽  
Dose Inhaler ◽  
Metered Dose Inhaler ◽  
Metered Dose ◽  
The Mean ◽  
Expiratory Flow

AbstractIntroduction:Although the efficacy of the administration of beta-adrenergic bronchodilators has been demonstrated, the best method available for the delivery of these drugs in the prehospital setting has not been defined. This paper compares the effects of administration of metaproterenol when administered by paramedics using either a metered-dose inhaler (MDI) or a hand-held nebulizer (HHN).Hypothesis:There is no difference in the effects produced in patients suffering from smooth bronchiolar muscle spasm by metaproterenol when delivered either by a standard metered-dose inhaler or with a hand-held nebulizer.Participants:Consecutive prehospital patients complaining of difficulty breathing with clinical evidence of bronchospasm and with a history of asthma, chronic obstructive pulmonary disease, or emphysema who were not in extremis.Methods:Prior to the administration of metaproterenol, a peak expiratory flow rate (PEFR) was obtained. This measurement was repeated five minutes following the conclusion of the administration of metaproterenol. Patients in Burbank, California, received the treatment using a standard metered-dose inhaler, and those in Madison, Wisconsin, received the drug using a hand-held nebulizer. Peak expiratory flow rates were compared using Student's t-tests with Bonferroni's correction. Statistical significance was set at p <0.05.Results:Data were collected from 36 consecutive patients by the paramedics of the Burbank Fire Department and from 32 consecutive patients by the paramedics of the Madison Fire Department. For the metered-dose inhaler group, the mean value for peak expiratory flow rate for the pre-treatment test was 95.4 ±88.1 1/min, and after treatment was 109.4 ±89.3 1/min (p <0.001). For the hand-held nebulizer group, the mean value for peak expiratory flow rate before the administration of the metaproterenol was 96.1 ±76.3 1/min and following the treatment was 149.1 ±92.9 1/min (p <0.001). The mean values for the differences between the control peak expiratory flow rate and the post-treatment peak expiratory flow rate for the metered-dose inhaler group was +14.0 ±27.4 1/min, and for the hand-held nebulizer group was +53.0 ±69.1 1/min (p <0.003).Conclusions:In the prehospital setting the administration of metaproterenol using a hand-held nebulizer is more effective than delivering the drug using a metered-dose inhaler. The hand-held nebulizer is easier to use and delivers a higher dose of the drug than is convenient using the metered-dose inhaler.

Flame Extinction Limits of H2‐CO Fuel Blends

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Ahsan R. Choudhuri ◽  
Mahesh Subramanya ◽  
Subramanyam R. Gollahalli
Keyword(s):  
Laminar Flame ◽  
Critical Value ◽  
Mean Value ◽  
Flame Velocity ◽  
Flame Extinction ◽  
Hydrogen Fuel ◽  
Fuel Blend ◽  
Fuel Blends ◽  
Extinction Limit ◽  
The Mean

The flame extinction limits of syngas (H2‐CO) flames were measured using a twin-flame counterflow burner. Plots of extinction limits (%f: volumetric percent of fuel in air) versus global stretch rates were generated at different fuel blend compositions and were extrapolated to determine the flame extinction limit corresponding to an experimentally unattainable zero-stretch condition. The zero-stretch extinction limit of H2‐CO mixtures decreases with the increase in H2 concentration in the mixture. The average difference between the measured flame extinction limit and the Le Chatelier’s calculation is around 7% of the mean value. The measured OH chemiluminescence data indicates that regardless of blend composition the OH radical concentration reduces to a critical value prior to the flame extinction. The measured laminar flame velocity close to the extinction indicates that regardless of fuel composition, the premixed flame of hydrogen fuel blends extinguishes when the mixture laminar flame velocity falls below a critical value.

scholarly journals Pigmentation Lesions and Salivary Flow Rates on Woman Smokers

2019 ◽  
Vol 22 (2) ◽  
pp. 34-38
Author(s):  
Aulia Fatimah ◽  
Sri Tjahajawati ◽  
Ervin Razali
Keyword(s):  
Flow Rate ◽  
Smoking Habit ◽  
Simple Random Sampling ◽  
Salivary Flow ◽  
Mean Value ◽  
Salivary Flow Rate ◽  
Negative Effects ◽  
Women Smokers ◽  
Descriptive Research ◽  
The Mean

Smoking habit has many negative effects towardswomen’s systemic and oral health. One of them are decrease of salivary flow rate and an appearance of pigmentation lesion in gingiva. The aim of this research is to obtain data regarding salivary flow rate and pigmentation lession on women smokers.This descriptive research used 50 samples by simple random sampling method. The salivary flow rate data was obtained by spitting method and the pigmentation lesion data was described by visual method. The other data wasobtained through filling the questionnaire. By the findings of this research, it was found that the mean value of salivary flow rate and pigmentation lession of women smokerswho consumed1-8 cigarettes per day for 1-2, 2-5 and > 5 years were 0.4 ml/min & 51,7%, 0.4 ml/min & 100%, 0.4 ml/min & 100%. The mean value of  salivary flow rate and pigmentation lession of women smokerswho consumed9-16 cigarettesper day for 1-2, 2-5 and > 5 years were 0.4 ml/min & 100%, 0.4 ml/min & 100%, 0.4 ml/min & 90%. The mean value of salivary flow rate and pigmentation lession of women smokerswho consumed>16 cigarettes per day for 1-2, 2-5 and > 5 years were 0.3 ml/min & 100%, 0.2 ml/min & 100%, 0.2 ml/min & 100%. The conclusion shows that salivary flow rate on women smokers has a lower value compared to normal salivary flow rate or its called oligosialia and most of the subjects have    

scholarly journals Study of the SCL-90 Scale and Changes in the Chinese Norms

2021 ◽  
Vol 11 ◽  
Author(s):  
Weimin Dang ◽  
Yajuan Xu ◽  
Jun Ji ◽  
Ke Wang ◽  
Songtao Zhao ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Detection Rate ◽  
Critical Value ◽  
Mean Value ◽  
Symptom Checklist ◽  
Measurement Standard ◽  
Standard Score ◽  
Usual Model ◽  
Significant Difference ◽  
The Mean

Objective: This study aimed to investigate the Chinese norms for the Symptom Checklist 90 (SCL-90) scale and its application.Methods: In total, 7,489 adults from Tianjin and Qingdao in China were included. Their data were compared with the norm data of 1,388 people published by Jin et al., the combined norms published by Tang et al., the data of 2,808 adults published by Chen and Li, and the data of 1,890 adults from Tong in China.Results: In five different periods, notable changes were observed in each factor of the SCL-90 that significantly differed from the previous norms. The scores of each factor showed an increasing annual trend. Compulsion consistently obtained the highest scores, and phobia consistently obtained the lowest scores. The scores tended to decrease from compulsion to anxiety, and psychosis scored lower than paranoia. There was a significant difference in the detection rate between the critical screening value of two points and the standard score. Using the standard score as the critical value, the detection rate ranged between 13 and 16% and was relatively concentrated. Using two points as the critical value, the detection rate ranged between 38 and 50%.Conclusion: The usual model in China is not consistent with social development. Using two points as the critical value is no longer suitable for the SCL-90. New Chinese norms and measurement standards should be developed. The mean value plus one standard deviation could be used as the new measurement standard.

scholarly journals A Simple, Innovative Way to Reduce Rhinitis Symptoms After Sedation during Endoscopy

2011 ◽  
Vol 25 (2) ◽  
pp. 68-72 ◽  
Author(s):  
Nai-Liang Li ◽  
Shiang-Chung Tseng ◽  
Che-Chang Hsu ◽  
Wei-Ju Lai ◽  
Hung-Chang Su ◽  
...  
Keyword(s):  
Flow Rate ◽  
Oxygen Delivery ◽  
Supplemental Oxygen ◽  
Mean Value ◽  
Nasal Mask ◽  
Oxygen Supplementation ◽  
Moderate Sedation ◽  
Patient Dissatisfaction ◽  
Nasal Symptoms ◽  
The Mean

BACKGROUND: Supplemental oxygen is routinely given via nasal cannula (NC) to patients undergoing moderate sedation for endoscopy. Some patients complain of profuse rhinorrhea and/or sneezing after the procedure, which results in additional medical costs and patient dissatisfaction.OBJECTIVES: To determine the causal relationship between the route of oxygen delivery and troublesome nasal symptoms, and to seek possible solutions.METHODS: Patients (n=836) were randomly assigned to one of the three following groups: the NC group (n=294), the trimmed NC (TNC) group (n=268) and the nasal mask (NM) group (n=274). All received alfentanil 12.5 μg/kg and midazolam 0.06 mg/kg, and adjunct propofol for sedation. Supplemental oxygen at a flow rate of 4 L/min was used in the NC and TNC groups, and 6 L/min in the NM group. The incidence of nasal symptoms and hypoxia were assessed.RESULTS: The incidence of rhinitis symptoms was significantly higher in the NC group (7.1%) than in the TNC (0.4%) and NM (0%) groups (P<0.001). The incidence of hypoxia was lower in the NC group (3.1%) (P=0.040). All hypoxia events were transient (ie, less than 30 s in duration). On spirometry, the mean value of the lowest saturation of peripheral oxygen was found to be significantly lower in the NM group (96.8%) than in the NC group (97.7%) (P=0.004).CONCLUSIONS: Trimming the NC or using NMs reduced the incidence of rhinitis symptoms; however, the incidence of hypoxia was higher. Further investigation regarding the efficiency of oxygen supplementation is warranted in the design of novel oxygen delivery devices.

scholarly journals Basal-flow characteristics of a linear medium sliding frictionless over small bedrock undulations

1997 ◽  
Vol 43 (143) ◽  
pp. 71-79 ◽  
Author(s):  
G. Hilmar Gudmundsson
Keyword(s):  
Flow Characteristics ◽  
Local Maximum ◽  
Critical Value ◽  
Two Dimensions ◽  
Creeping Flow ◽  
Wave Number ◽  
Vertical Position ◽  
Gravity Driven ◽  
The Mean ◽  
Basal Flow

AbstractThe basal deformation of a gravity-driven linear creeping flow sliding frictionless over slowly varying bed undulations in two dimensions is analysed analytically, using results from second-order perturbation theory. One of the key results is that, close to sinusoidal bedrock undulations, up to two different spatial regions of local extrusion flow may arise. The offset and onset of extrusion flow is controlled primarily by the amplitude-to-wavelength ratio. Above the crest of a sinusoidal bed line, a local maximum of the surface-parallel velocity develops for ε : = ak < 0.138, where a is the amplitude and k is the wave number. As ε increases from zerо to this critical value, the vertical position of the velocity maximum moves from kz = 1 to kz ≈ 1.98, where z is the vertical distance above the mean bed line. Within and above the trough of a sinusoid, a region of local minimum of the surface-parallel velocity component develops, which shifts from kz = 1 towards the bed line as ε increases front zero to 1/2. Below this velocity minimum, and for some distance above the velocity maximum, the surface-parallel velocity increases with depth. This type of extrusion flow will cause a reversal of borehole-inclination profiles close to the bedrock.

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