Slow waves of boiling under hot water depressurization

Experimental studies of hot water depressurization show that the pressure in a vessel, just after it is opened, drops much lower than the pressure of saturation but the liquid does not boil uniformly throughout the vessel. Essentially, liquid boiling begins only on the arrival of a ‘slow wave’ of rarefaction which moves at a low speed of approximately 10 m s−1 from the open end deep into the vessel.To explain this phenomenon we suggest a model that takes into account the difference in phase velocities. Although this difference in bubble flows is only about 1 m s−1 it proves to be sufficient to cause bubble breakup. Using this model we obtained the ‘slow wave of boiling’ in a numerical experiment that was in good agreement with the physical experiment.

Download Full-text

Dynamics of an isolated barotropic eddy on a beta-plane

Journal of Fluid Mechanics ◽

10.1017/s0022112094000662 ◽

1994 ◽

Vol 264 ◽

pp. 277-301 ◽

Cited By ~ 16

Author(s):

Gennady K. Korotaev ◽

Alexander B. Fedotov

Keyword(s):

Kinetic Energy ◽

Analytical Solution ◽

Numerical Experiment ◽

Point Vortex ◽

Vortex Sheet ◽

The Other ◽

Beta Plane ◽

The Difference ◽

Experimental Values ◽

Good Agreement

The dynamics of a Gaussian isolated barotropic eddy on a β-plane is considered. The analytical solution of the evolution of an isolated vortex is constructed by analogy to the theory of a point vortex. The results of a numerical experiment are compared with the conclusions of the theory for the case of the Gaussian vortex. Characteristics of the vortex such as its radius, trajectory of movement, kinetic energy, residual vorticity, and the structure of the vortex are discussed. The analysis of the numerical results shows that the experimentally determined radius of the vortex, its energy, and residual vorticity are in good agreement with the theory. On the other hand there is a difference between analytical and experimental values of velocity components, and hence in the trajectory of the centre of the vortex. The location of the separatrix of the streak function and its saddle point are considered as important characteristics of the structure of the vortex. We consider the phenomenon of the generation of the vortex sheet connected with the separatrix location as a cause of the difference between the experimental and analytical estimates of the velocity of the vortex.

Download Full-text

Shape of an Annular Liquid Jet

Journal of Fluids Engineering ◽

10.1115/1.2819285 ◽

1997 ◽

Vol 119 (3) ◽

pp. 591-596 ◽

Cited By ~ 6

Author(s):

M. Z. Hasan ◽

Y. Mitsutake ◽

M. Monde

Keyword(s):

Experimental Studies ◽

Liquid Jet ◽

Analytical Prediction ◽

Order Ordinary Differential Equation ◽

Annular Jet ◽

Different Shapes ◽

Annular Liquid Jet ◽

The Difference ◽

Inertia Forces ◽

Good Agreement

Analytical and experimental studies have been done to determine the shape of a vertical, axisymmetric, annular liquid jet. From a balance of the surface, pressure, gravity, and inertia forces, a nonlinear, second-order, ordinary differential equation is obtained for the shape of the annular jet. This equation is solved numerically by the Runge-Kutta-Nystro¨m method. An annular jet either converges (closes), diverges, or maintains (theoretically) its original radius depending upon the magnitude of the difference between the inside and outside pressure. This corresponds to, in terms of a dimensionless pressure p, whether p is less than, greater than, or equal to 2. An experiment has been performed to verify the analytical solution. The jet velocity, inside pressure and other parameters have been varied to obtain different shapes of the jet, both closing and diverging. Good agreement with the analytical prediction is found.

Download Full-text

Explaining the magnetism of gold

10.26434/chemrxiv.5393944.v1 ◽

2017 ◽

Author(s):

Robson de Farias

Keyword(s):

Gas Phase ◽

Computational Study ◽

Formation Enthalpy ◽

Gold Atom ◽

Orbital Energy ◽

Knudsen Effusion ◽

Energy Diagram ◽

Unpaired Electrons ◽

The Difference ◽

Good Agreement

In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au2 (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au2, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au2 with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol-1), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol-1 to the Au-Au bond7. So, as expected, in the specie with none unpaired electrons, the two 6s1 (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au2 with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au2 is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).

Download Full-text

Perbedaan Metode Three Compartement Sink dengan Air Panas dan Larutan Klorin terhadap Angka Kuman Alat Makan di RSU Queen Latifa

JURNAL NUTRISIA ◽

10.29238/jnutri.v19i2.27 ◽

2017 ◽

Vol 19 (2) ◽

pp. 126-130

Author(s):

Rifatun Hasanah ◽

Setyowati Setyowati ◽

Noor Tifauzah

Keyword(s):

Infectious Diseases ◽

Confidence Level ◽

Disease Transmission ◽

T Test ◽

Hot Water ◽

Independent Test ◽

The Difference ◽

Hospital Use

Background:One of the efforts in preventing congenital food disease is by washing the cutlery perfectly. The cutlery used by patients with infectious diseases should be noted more, because it has a risk in disease transmission through cutlery. The process of washing the cutlery for infected patients in Queen Latifa Hospital use three compartement sink method with hot water, while the three compartement sink method with clorine solvent has never been tested. Purpose: Research was to determine the difference in the number of germs in the tool was washed using three compartement sink method with hot water and with clorine solvent. Method:Types of research is experiment with rancangan percobaan acak kelompok (RAK). The object of this research is 4 plates and 4 bowls. The number of experimental units in this research were 2 treatments x 2 cutlery x 2 checks x 2 reapetitions = 16 experimental units. The analysis used independent t-test with 95% confidence level. Result :The average number of germs in the cutlery washed using the three compartment sink method with hot water was 1 x 101 cfu / cm2, whereas with chlorine solvent is 0.2 cfu / cm2. Independent test t-test shows p = 0.049 which means the hypothesis is accepted. onclusion : There are differences in the number of germs in the washing cutlery using the three compartment sink method with hot water and with chlorine solvent. Keywords: number of germs, cutlery, three compartment sink

Download Full-text

Perbedaan Metode Three Compartement Sink dengan Air Panas dan Larutan Klorin terhadap Angka Kuman Alat Makan di RSU Queen Latifa

JURNAL NUTRISIA ◽

10.29238/jnutri.v19i2.262 ◽

2017 ◽

Vol 19 (2) ◽

pp. 126

Author(s):

Rifatun Hasanah ◽

Setyowati Setyowati ◽

Noor Tifauzah

Keyword(s):

Infectious Diseases ◽

Confidence Level ◽

Disease Transmission ◽

T Test ◽

Hot Water ◽

Independent Test ◽

The Difference ◽

Hospital Use

Background:One of the efforts in preventing congenital food disease is by washing the cutlery perfectly. The cutlery used by patients with infectious diseases should be noted more, because it has a risk in disease transmission through cutlery. The process of washing the cutlery for infected patients in Queen Latifa Hospital use three compartement sink method with hot water, while the three compartement sink method with clorine solvent has never been tested. Purpose: Research was to determine the difference in the number of germs in the tool was washed using three compartement sink method with hot water and with clorine solvent. Method:Types of research is experiment with rancangan percobaan acak kelompok (RAK). The object of this research is 4 plates and 4 bowls. The number of experimental units in this research were 2 treatments x 2 cutlery x 2 checks x 2 reapetitions = 16 experimental units. The analysis used independent t-test with 95% confidence level. Result :The average number of germs in the cutlery washed using the three compartment sink method with hot water was 1 x 101 cfu / cm2, whereas with chlorine solvent is 0.2 cfu / cm2. Independent test t-test shows p = 0.049 which means the hypothesis is accepted. Conclusion : There are differences in the number of germs in the washing cutlery using the three compartment sink method with hot water and with chlorine solvent.

Download Full-text

Effect of leakage and blockage on the acoustic behavior of particle filters

Noise Control Engineering Journal ◽

10.3397/1/376744 ◽

2019 ◽

Vol 67 (6) ◽

pp. 483-492

Author(s):

Seonghyeon Baek ◽

Iljae Lee

Keyword(s):

Transfer Matrix ◽

Particle Filters ◽

Acoustic Analysis ◽

Transmission Loss ◽

One Dimensional ◽

Filter System ◽

The Difference ◽

The One ◽

Analytical Approaches ◽

Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

Download Full-text

Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

Annals of Glaciology ◽

10.1017/s0260305500012143 ◽

1997 ◽

Vol 24 ◽

pp. 181-185 ◽

Cited By ~ 3

Author(s):

Katsuhisa Kawashima ◽

Tomomi Yamada

Keyword(s):

Experimental Studies ◽

Ice Formation ◽

Compression Tests ◽

Densification Rate ◽

Overburden Pressure ◽

Proportionality Constant ◽

Wet Snow ◽

Water Saturated ◽

The Relationship ◽

Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

Download Full-text

The Aging Slow Wave: A Shifting Amalgam of Distinct Slow Wave and Spindle Coupling Subtypes Define Slow Wave Sleep Across the Human Lifespan

SLEEP ◽

10.1093/sleep/zsab125 ◽

2021 ◽

Author(s):

Brice V McConnell ◽

Eugene Kronberg ◽

Peter D Teale ◽

Stefan H Sillau ◽

Grace M Fishback ◽

...

Keyword(s):

Slow Wave ◽

Neurological Disease ◽

Mixed Model ◽

Slow Wave Sleep ◽

Sleep Stage ◽

Slow Waves ◽

Cross Sectional ◽

Relative Contribution ◽

Human Lifespan ◽

Development And Aging

Abstract Study Objectives Slow wave and spindle coupling supports memory consolidation, and loss of coupling is linked with cognitive decline and neurodegeneration. Coupling is proposed to be a possible biomarker of neurological disease, yet little is known about the different subtypes of coupling that normally occur throughout human development and aging. Here we identify distinct subtypes of spindles within slow wave upstates and describe their relationships with sleep stage across the human lifespan. Methods Coupling within a cross-sectional cohort of 582 subjects was quantified from stages N2 and N3 sleep across ages 6-88 years old. Results were analyzed across the study population via mixed model regression. Within a subset of subjects, we further utilized coupling to identify discrete subtypes of slow waves by their coupled spindles. Results Two different subtypes of spindles were identified during the upstates of (distinct) slow waves: an “early-fast” spindle, more common in stage N2 sleep, and a “late-fast” spindle, more common in stage N3. We further found stages N2 and N3 sleep contain a mixture of discrete subtypes of slow waves, each identified by their unique coupled-spindle timing and frequency. The relative contribution of coupling subtypes shifts across the human lifespan, and a deeper sleep phenotype prevails with increasing age. Conclusions Distinct subtypes of slow waves and coupled spindles form the composite of slow wave sleep. Our findings support a model of sleep-dependent synaptic regulation via discrete slow wave/spindle coupling subtypes and advance a conceptual framework for the development of coupling-based biomarkers in age-associated neurological disease.

Download Full-text

Effect of Magnetic Fields on the Resistance and Microstructure of Al-Cu Alloy during Solidification Processing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.287-290.2916 ◽

2011 ◽

Vol 287-290 ◽

pp. 2916-2920

Author(s):

Chun Yan Ban ◽

Peng Qian ◽

Xu Zhang ◽

Qi Xian Ba ◽

Jian Zhong Cui

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Turning Points ◽

Probe Method ◽

Solidification Processing ◽

Ac Magnetic Field ◽

Dc Magnetic Field ◽

Cu Alloy ◽

The Difference ◽

Good Agreement

The resistance of Al-21%Cu alloy under no magnetic field, DC magnetic field and AC magnetic field from liquid to solid was measured by a four-probe method. The difference of resistance versus temperature curves (R-T curves) was analyzed. It is found that the R-T curves of Al-21%Cu alloy are monotone decreasing and have two obvious turning points. Under DC magnetic field, the liquidus and solidus temperatures of the alloy both decrease, while under AC magnetic field, the liquidus and solidus temperatures both increase. There is a good agreement between the microstructure of quenching sample and R-T curves. The mechanism of the effect of magnetic fields was discussed.

Download Full-text

Local atomic structure in tetragonal pure ZrO2nanopowders

Journal of Applied Crystallography ◽

10.1107/s0021889809054983 ◽

2010 ◽

Vol 43 (2) ◽

pp. 227-236 ◽

Cited By ~ 16

Author(s):

Leandro M. Acuña ◽

Diego G. Lamas ◽

Rodolfo O. Fuentes ◽

Ismael O. Fábregas ◽

Márcia C. A. Fantini ◽

...

Keyword(s):

Tetragonal Phase ◽

Local Structure ◽

X Ray Diffraction ◽

X Ray ◽

Atomic Structures ◽

Crystallite Sizes ◽

Exafs Study ◽

The Difference ◽

X Ray Absorption ◽

Good Agreement

The local atomic structures around the Zr atom of pure (undoped) ZrO2nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr—O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye–Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to thezdirection; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

Download Full-text