Merging of Horizontally and Vertically Separated Small-Scale Buoyant Flames

The purpose of this study was to investigate the merging behavior of small-scale buoyant flames that might be representative of flames from a leaf in a shrub. Zirconia felt pads soaked in n-heptane were suspended on thin rods and spaced both horizontally and vertically. Time-dependent video images from flames from two-pad and three-pad configurations were analyzed to determine merging probability, combined flame characteristics (height, area, and width), and changes in burn time. Correlations of these combined flame characteristics were developed based on horizontal and vertical spacing between the pads. Merging probability correlated with an exponential function that was quadratic in horizontal and/or vertical spacing. Flame heights corrected for vertical inter-pad spacing showed a maximum increase of 50% over single flame heights, and were correlated with an exponential decay function. Flame areas increased by a maximum of 34%, but on average were relatively constant. Corrected flame widths for the merged flames increased by as much as 55% in some configurations, but decreased by up to 73% in other configurations. Burn times for upper pads decreased when there was no horizontal spacing. The limited flame growth observed in these non-overlapping configurations in the horizontal dimension imply that overlapping configurations seem to be necessary for significant flame growth.

Download Full-text

Microdeformations in Sands by Digital Image Processing and Analysis

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198196154800105 ◽

1996 ◽

Vol 1548 (1) ◽

pp. 31-37 ◽

Cited By ~ 5

Author(s):

Scott A. Raschke ◽

Roman D. Hryciw ◽

Gregory W. Donohoe

Keyword(s):

Image Processing ◽

Digital Image Processing ◽

Digital Image ◽

Small Scale ◽

Two Dimensional ◽

Localized Deformation ◽

Displacement Fields ◽

Particulate Media ◽

Image Processing And Analysis ◽

Video Images

Laboratory experiments are typically performed on particulate media to study stress-deformation behavior and to verify or calibrate computer models from controlled or measured boundary stresses and displacements. However, such data do not permit the formation of shear bands, displacement fields within flowing granular media, and other small-scale localized deformation phenomena to be identified. Described are two semiautomated computer vision techniques for accurately determining the two-dimensional displacement field in granular soils from video images obtained through a transparent planar viewing window. The techniques described are applicable for studying the behavior of particulate media under plane strain and certain axisymmetric test conditions. Digital image processing and analysis routines are used in two different computer programs, Tracker and Tracer, Tracker uses a graphical user interface that allows individual particles to be selected and tracked through a sequence of digital video images. A contrast edge detection algorithm delineates the two-dimensional projected boundaries of particles. The location of the centroid of each particle selected for tracking is determined from the boundary to quantify the trajectory of each particle. Tracer maps the trace or trajectory of specially dyed fluorescent particles in a sequence of video frames. A thresholding technique segments individual particle trajectories. Together, Tracker and Tracer provide a set of tools for identifying small-scale displacement fields in particulate assemblies deforming under either quasi-static or rapid loading (such as gravity flow).

Download Full-text

Development of Computer Vision Technique for in Situ Soil Characterization

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198196152600111 ◽

1996 ◽

Vol 1526 (1) ◽

pp. 86-97 ◽

Cited By ~ 7

Author(s):

Roman D. Hryciw ◽

Scott A. Raschke

Keyword(s):

Computer Vision ◽

Vision System ◽

Cohesionless Soil ◽

Software Systems ◽

Small Scale ◽

Second Phase ◽

Video Images ◽

Subsurface Soil ◽

Different Levels

Construction and rehabilitation of highways, tunnels, and bridges require detailed information about subsurface stratigraphy. This study presents development of a new method for characterizing subsurface soil in situ using computer vision. Hardware and software systems are integrated to obtain the grain-size distribution (GSD) of subsurface soils continuously with depth and to identify small-scale subsurface anomalies. Research is being conducted in three phases. The first phase consists of measuring the GSD of detached cohesionless soil specimens in the laboratory from digital images obtained with a computer vision system (CVS). The second phase uses the CVS to develop image processing and analysis techniques to classify soil assemblies in the laboratory and identify subsurface anomalies by simulating the manner in which images will be acquired in situ. A texture analysis approach has been developed that can detect changes in stratigraphy. The technique has been successful in identifying different types of dry, uniformly graded soils. Finally, a subsurface vision probe is being designed and constructed that will capture video images at three different levels of magnification continuously with depth.

Download Full-text

Evidence for Time-dependent Maximum Increase of Free Radical Damage and Eicosanoid Formation in the Brain as Related to Duration of Cardiac Arrest and Cardio-pulmonary Resuscitation

Free Radical Research ◽

10.1080/1071576021000043058 ◽

2003 ◽

Vol 37 (3) ◽

pp. 251-256 ◽

Cited By ~ 34

Author(s):

Samar Basu ◽

Xiaoli Liu ◽

Ala Nozari ◽

Sten Rubertsson ◽

Adriana Miclescu ◽

...

Keyword(s):

Cardiac Arrest ◽

Free Radical ◽

Time Dependent ◽

Maximum Increase ◽

Free Radical Damage ◽

Cardio Pulmonary Resuscitation ◽

The Brain ◽

Radical Damage ◽

Eicosanoid Formation

Download Full-text

Exponential function for calculating saturable enzyme kinetics.

Clinical Chemistry ◽

10.1093/clinchem/34.12.2486 ◽

1988 ◽

Vol 34 (12) ◽

pp. 2486-2489 ◽

Cited By ~ 3

Author(s):

F Keller ◽

C Emde ◽

A Schwarz

Keyword(s):

Steady State ◽

Enzyme Kinetics ◽

Exponential Function ◽

Association Constant ◽

Time Dependent ◽

Mathematical Representation ◽

Hyperbolic Function ◽

Maximal Velocity ◽

Michaelis Constant ◽

General Meaning

Abstract Enzyme kinetics are usually described by the Michaelis-Menten equation, where the time-dependent decrease of substrate (-dS/dt) is a hyperbolic function of maximal velocity (Vmax), Michaelis constant (Km), and amount of substrate (S). Because the Michaelis-Menten function in its most general meaning requires an assumption of steady-state, it is less curvilinear than true enzyme kinetics. A saturation-type exponential function is more curvilinear than the hyperbolic function and more closely approximates enzyme kinetics: -dS/dt = Vmax [1 - exp(-S/Km)]. The mathematical representation of enzyme kinetics can be further improved by introducing a deceleration term (Vdec), to make the assumption of a steady state unnecessary. For the action of chymotrypsin on N-acetyltyrosylethylester, the Michaelis-Menten equation yields the following: Vmax = 3.74 mumol/min and Km = 833 mumol. According to decelerated enzyme kinetics, the values Vmax = 4.80 mumol/min, Vdec = 0.0118 mumol/min, and the association constant (Ka) = 0.00111/mumol are more nearly accurate for this reaction (where 1/Ka = 901 mumol approximately Km).

Download Full-text

Two-Dimensional, Time-dependent Modelling of an Arbitrarily Shaped Ice Mass with the Finite-Element Technique

Journal of Glaciology ◽

10.1017/s0022143000006699 ◽

1985 ◽

Vol 31 (109) ◽

pp. 350-359 ◽

Cited By ~ 8

Author(s):

Steven M. Hodge

Keyword(s):

Finite Element ◽

Numerical Models ◽

Basis Functions ◽

Time Dependent ◽

Small Computer ◽

Two Dimensional ◽

Maximum Increase ◽

Steady State Condition ◽

Finite Element Technique ◽

Element Technique

AbstractThe two-dimensional, time-dependent flow of an arbitrarily shaped ice mass can be successfully modeled with the finite-element technique on a small computer. Methods developed for automatically generating the mesh data greatly simplify the data preparation and optimize the numerical simulations. Using quadratic basis functions permits the flow to be approximated quite adequately by only two element rows (five nodes vertically). Mixed-order basis functions, however, must be used so that numerical oscillations do not set in, and the ends of the ice mass, where the thickness tends to zero, must be treated carefully. Time simulations to a steady-state condition are necessary to test such numerical models adequately.South Cascade Glacier, Washington, is currently close to equilibrium. A bedrock sill dominates the bed topography in the lower half of the glacier, rising to a height of about 20% of the ice thickness. This sill produces a maximum increase in the overall thickness of about 6–7% compared to what the thickness would have been if the sill were not present. Finally, this glacier does not appear to be sliding much, if at all, despite its maritime alpine environment. This could help explain the difficulties encountered when trying to measure sliding and basal water pressures on the same glacier (Hodge, 1979), or it could imply that drag exerted by the valley walls has a significantly greater effect than conventional shape-factor concepts imply.

Download Full-text

Environmental Surveillance Can Dynamically Track Ecological Changes in Enteroviruses

Applied and Environmental Microbiology ◽

10.1128/aem.01604-19 ◽

2019 ◽

Vol 85 (24) ◽

Cited By ~ 2

Author(s):

Hiroki Ozawa ◽

Hiromu Yoshida ◽

Shuzo Usuku

Keyword(s):

Multidimensional Scaling ◽

Large Scale ◽

Local Community ◽

Amino Acid Sequences ◽

Time Dependent ◽

Small Scale ◽

Dependent Manner ◽

Environmental Surveillance ◽

Ecological Changes ◽

Over Time

ABSTRACT Environmental surveillance can be used to trace enteroviruses shed from human stool using a sewer network that is independent of symptomatic or asymptomatic infection. In this study, the local transmission of enteroviruses was analyzed using two wastewater treatment plants, which were relatively close to each other (15 km), designated as sentinels. Influent was collected at both sentinels once a month from 2013 to 2016, and viruses were isolated. Using neutralizing tests with type-specific polyclonal antisera and molecular typing, 933 isolates were identified as enteroviruses. Our results showed that the frequency of virus isolation varied for each serotype at the two sentinels in a time-dependent manner. Because echovirus 11 (Echo11) and coxsackievirus B5 isolates showed a high frequency and were difficult to distinguish, they were further grouped into various lineages based on the VP1 amino acid sequences. The prevalence of each lineage was visualized using multidimensional scaling. The results showed that Echo11 isolates of the same lineage were isolated continuously, similar to coxsackievirus B5 isolates of three lineages. Conversely, Echo1, Echo13, Echo18, Echo19, Echo20, Echo29, and Echo33 were isolated only once each. Our findings suggested that if an enterovirus is imported into the population, it may result in small-scale transmission, whereas if there are initially many infected individuals, it may be possible for the virus to spread to a wide area, beyond the local community, over time. In addition, our findings could provide insights into risk assessment of transmission for importation of poliovirus in polio-free countries and regions. IMPORTANCE In this study, we showed that environmental enterovirus surveillance can be used to monitor the propagation of nonpolio enteroviruses in addition to poliovirus detection. Since epidemiological studies of virus transmission based on the past were performed using specimens from humans, there were limitations to research design, such as specimen collection for implementation on a large-scale target population. However, environmental monitoring can dynamically track the ecological changes in enteroviruses in the region by monitoring viruses in chronological order and targeting the population within the area by monitoring viruses over time. We observed differences in the transmission of echovirus 11 and coxsackievirus B5 in the region according to lineage in a time-dependent manner and with a multidimensional scaling pattern.

Download Full-text

Experimental Methodology and Facility for the J69-Engine Performance and Emissions Evaluation Using Jet A1 and Biodiesel Blends

Energies ◽

10.3390/en12234530 ◽

2019 ◽

Vol 12 (23) ◽

pp. 4530 ◽

Cited By ~ 2

Author(s):

Gabriel Talero ◽

Camilo Bayona-Roa ◽

Giovanny Muñoz ◽

Miguel Galindo ◽

Vladimir Silva ◽

...

Keyword(s):

Fossil Fuels ◽

Fuel Injection ◽

Engine Performance ◽

Injection Pressure ◽

Experimental Tests ◽

Experimental Methodology ◽

Injection System ◽

Small Scale ◽

Gas Temperature ◽

Maximum Increase

Aeronautic transport is a leading energy consumer that strongly contributes to greenhouse gas emissions due to a significant dependency on fossil fuels. Biodiesel, a substitution of conventional fuels, is considered as an alternative fuel for aircrafts and power generation turbine engines. Unfortunately, experimentation has been mostly limited to small scale turbines, and technical challenges remain open regarding operational safety. The current study presents the facility, the instrumentation, and the measured results of experimental tests in a 640 kW full-scale J69-T-25A turbojet engine, operating with blends of Jet A1 and oil palm biodiesel with volume contents from 0% to 10% at different load regimes. Findings are related to the fuel injection system, the engine thrust, and the emissions. The thrust force and the exhaust gas temperature do not expose a significant variation in all the operation regimes with the utilization of up to 10% volume content of biodiesel. A maximum increase of 36% in fuel consumption and 11% in injection pressure are observed at idle operation between B0 and B10. A reduction of the CO and HC emissions is also registered with a maximum variation at the cruise regime (80% Revolutions Per Minute—RPM).

Download Full-text

Wideband and Ultrawideband Channel Models in Working Machine Environment

Modelling and Simulation in Engineering ◽

10.1155/2012/702917 ◽

2012 ◽

Vol 2012 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Attaphongse Taparugssanagorn ◽

Matti Hämäläinen ◽

Jari Iinatti

Keyword(s):

Exponential Decay ◽

Radio Channel ◽

Line Of Sight ◽

Small Scale ◽

Delay Spread ◽

Confined Space ◽

Rms Delay Spread ◽

Decay Profile ◽

Cabin Environment ◽

Uwb Radio

We present statistical models for wideband and ultrawideband (UWB) radio channels in a working machine cabin environment. Based on a set of measurements, it was found that such a small and confined space causes mostly diffuse multipath scattering rather than specular paths. The amplitude of the channel impulse responses in the wideband case is mostly Rayleigh distributed small-scale fading signal, with only a few paths exhibiting Ricean distributions, whereas the ones in the UWB case tend to be log-normally distributed. For the path amplitude, we suggest an exponential decay profile, which has a constant slope in dB scale, with the corresponding parameters for the UWB case. For the wideband case, a twofold exponential decay profile provides excellent fits to the measured data. It was also noted that the root-mean-square (RMS) delay spread is independent of the line-of-sight/obstructed line-of-sight situations of the channel. The multipath components contributing significant energy play a major role in such a small environment if compared to the direct path. In addition, the radio channel gains are attenuated with the presence of a driver inside the cabin.

Download Full-text