scholarly journals Experimental Assessment of Water Hammer-Induced Column Separation in Oil-Hydraulic Pipe Flow

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Marcus Jansson ◽  
Magnus Andersson ◽  
Maria Pettersson ◽  
Matts Karlsson
Keyword(s):  
Cavitation Erosion ◽  
Water Hammer ◽  
Hydraulic Test ◽  
Delay Reduction ◽  
Simulation Tools ◽  
Column Separation ◽  
Temperature Ranges ◽  
Good Repeatability ◽  
Lower Temperature ◽  
Future Work

Cavitation erosion through water hammer and column separation is a major concern in hydraulic applications such as percussive rock drilling. Cavitation aspects must be considered both in early and late design stages, which require deep knowledge and tools for prediction. In this study, an oil-hydraulic test equipment for water hammer assessment was designed using state-of-the-art simulation tools. Several tests were performed, with and without column separation, showing good repeatability on measured pressures. At higher flow rates, column separation was the dominating feature and several high-pressure peaks with subsequent time delay reduction could be observed. These patterns were affected by the oil temperature, with most substantial changes at lower temperature ranges (<32 °C). Standard transmission line simulations managed to predict the water hammer, but as expected not the column separation, which is the theme of future work using this setup.

scholarly journals State-of-art review of traffic signal control methods: challenges and opportunities

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Syed Shah Sultan Mohiuddin Qadri ◽  
Mahmut Ali Gökçe ◽  
Erdinç Öner
Keyword(s):  
Daily Basis ◽  
Traffic Signal ◽  
Signal Control ◽  
Traffic Signal Control ◽  
Urban Network ◽  
Simulation Tools ◽  
Challenges And Opportunities ◽  
Traffic Signal Timing ◽  
Increasing Demand ◽  
Future Work

Abstract Introduction Due to the menacing increase in the number of vehicles on a daily basis, abating road congestion is becoming a key challenge these years. To cope-up with the prevailing traffic scenarios and to meet the ever-increasing demand for traffic, the urban transportation system needs effective solution methodologies. Changes made in the urban infrastructure will take years, sometimes may not even be feasible. For this reason, traffic signal timing (TST) optimization is one of the fastest and most economical ways to curtail congestion at the intersections and improve traffic flow in the urban network. Purpose Researchers have been working on using a variety of approaches along with the exploitation of technology to improve TST. This article is intended to analyze the recent literature published between January 2015 and January 2020 for the computational intelligence (CI) based simulation approaches and CI-based approaches for optimizing TST and Traffic Signal Control (TSC) systems, provide insights, research gaps and possible directions for future work for researchers interested in the field. Methods In analyzing the complex dynamic behavior of traffic streams, simulation tools have a prominent place. Nowadays, microsimulation tools are frequently used in TST related researches. For this reason, a critical review of some of the widely used microsimulation packages is provided in this paper. Conclusion Our review also shows that approximately 77% of the papers included, utilizes a microsimulation tool in some form. Therefore, it seems useful to include a review, categorization, and comparison of the most commonly used microsimulation tools for future work. We conclude by providing insights into the future of research in these areas.

scholarly journals Creep deformation behavior during densification of ZrB2-SiBCN ceramics with ZrO2 additive

2020 ◽  
Vol 9 (5) ◽  
pp. 544-557
Author(s):  
Bo Feng ◽  
Zhenhang Wang ◽  
Yunhao Fan ◽  
Jinghua Gu ◽  
Yue Zhang
Keyword(s):  
Grain Boundary ◽  
Creep Deformation ◽  
Applied Pressure ◽  
Grain Boundary Sliding ◽  
Diffusion Creep ◽  
Atom Diffusion ◽  
Grain Boundary Mobility ◽  
Controlling Mechanism ◽  
Temperature Ranges ◽  
Lower Temperature

Abstract ZrB2-SiBCN ceramics with ZrO2 additive are hot-pressed under a constant applied pressure. The densification behavior of the composites is studied in a view of creep deformation by means of the Bernard-Granger and Guizard model. With determination of the stress exponent (n) and the apparent activation energy (Qd), the specific deformation mechanisms controlling densification are supposed. Within lower temperature ranges of 1300–1400 °C, the operative mechanism is considered to be grain boundary sliding accommodated by atom diffusion of the polymer-derived SiBCN (n = 1, Qd = 123±5 kJ/mol) and by viscous flow of the amorphous SiBCN (n = 2, Qd = 249±5 kJ/mol). At higher temperatures, the controlling mechanism transforms to lattice or intra-granular diffusion creep (n = 3–5) due to gradual consumption of the amorphous phase. It is suggested that diffusion of oxygen ions inside ZrO2 into the amorphous SiBCN decreases the viscosity, modifies the fluidity, and contributes to the grain boundary mobility.

scholarly journals Internal Friction and Dynamic Modulus in Ultra-High Temperature Ru-Nb Functional Intermetallics / Tarcie Wewnętrzne I Moduł Dynamiczny W Bardzo Wysoko Temperaturowych Funkcjonalnych Związkach Międzymetalicznych Z Układu Ru-Nb

2015 ◽  
Vol 60 (4) ◽  
pp. 3069-3072
Author(s):  
M.L. Nó ◽  
L. Dirand ◽  
A. Denquin ◽  
J. San Juan
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Martensitic Transformations ◽  
Time Dependent ◽  
Structural Defects ◽  
Complete Analysis ◽  
Internal Friction Peak ◽  
Thermally Activated ◽  
Temperature Ranges ◽  
Lower Temperature

In the present work we have studied the high-temperature shape memory alloys based on the Ru-Nb system by using two mechanical spectrometers working in temperature ranges from 200 to 1450ºC and -150 to 900ºC. We have studied internal friction peaks linked to the martensitic transformations in the range from 300 to 1200ºC. In addition, we have evidenced another internal friction peak at lower temperature than the transformations peaks, which apparently exhibits the behaviour of a thermally activated relaxation peak, but in fact is a strongly time-dependent peak. We have carefully studied this peak and discussed its microscopic origin, concluding that it is related to the interaction of some structural defects with martensite interfaces. Finally, we perform a complete analysis of the whole internal friction spectrum, taking into account the possible relationship between the time-dependent peak and the martensitic transformation behaviour.

Phosphors for remote thermograph sensing in lower temperature ranges

1996 ◽  
Vol 32 (3) ◽  
pp. 253 ◽  
Author(s):  
A.J. Simons ◽  
I.P. McClean ◽  
R. Stevens
Keyword(s):  
Temperature Ranges ◽  
Lower Temperature

Stratified Flow Experiments Pertaining to Advanced LWR Reactor Passive Safety System Designs

2004 ◽  
Author(s):  
Jim C. P. Liou ◽  
Alan G. Stephens ◽  
Richard R. Schultz
Keyword(s):  
Flow Behavior ◽  
Stratified Flow ◽  
Water Hammer ◽  
Test Facility ◽  
Light Water Reactors ◽  
Loss Of Coolant Accident ◽  
Passive Safety System ◽  
Water Reactors ◽  
Lower Temperature ◽  
System Designs

During a loss-of-coolant-accident in advanced light water reactors, outside coolant enters the cold leg by gravity to cool the core. This coolant is at a substantially lower temperature and thus is heavier than the liquid in and from the reactor. Consequently, stratified flow may occur. A stratified flow may cause condensation-induced water hammer, and will influence the coolant flow behavior. Two sets of experiments are in progress to better understand stratified flow conditions that lead to water hammer, and the density stratification behavior. The first set uses air-oil-water as the test media. Its purposes are to conduct exploratory tests and to provide instruction an apparatus for education purposes. The second set of tests will use steam and water and, later, the refrigerant R123. This paper describes the exploratory test facility, gives a brief description of the facility that will be used for the steam-water and refrigerant tests, describes the overall test plan, and finally gives some preliminary results on the intrusion of a lighter liquid into a pipe against flow.

Evaluation of CO2 Absorbent/De-Absorbent by AAO/CaO Membrane

2013 ◽  
Vol 690-693 ◽  
pp. 1856-1859
Author(s):  
Chien Chon Chen ◽  
Yen Po Wang
Keyword(s):  
Anodic Aluminum Oxide ◽  
Sol Gel ◽  
Core Shell ◽  
Anodic Aluminum ◽  
Temperature Ranges ◽  
Higher Temperature ◽  
Co2 Absorbent ◽  
Lower Temperature ◽  
The Relationship ◽  
Fuel Material

This paper discussed the fabrication of anodic aluminum oxide (AAO)/CaO core-shell membrane by anodization and sol-gel processes and evaluated the relationship between the Al2O3/CaO and CO2 by thermodynamic calculation. According to thermodynamic property that CaO can reacts with CO2 forming calcium carbonate (CaCO3) in a lower temperature ranges, CaCO3 can also be decomposed to CaO in a higher temperature ranges. Because the reversible reaction property that CaO can be a CO2 absorbent/ de-absorbent. We address that AAO based on core-shell nanotubes structure to achieve such a demand. The captured CO2 can further convert to fuel material of hydrocarbons.

scholarly journals The effects of temperature on the kinetics and stability of mesophilic and thermophilic 3-phosphoglycerate kinases

1998 ◽  
Vol 330 (3) ◽  
pp. 1087-1095 ◽  
Author(s):  
M. Theresa THOMAS ◽  
K. Robert SCOPES
Keyword(s):  
Growth Temperature ◽  
Phosphoglycerate Kinase ◽  
Theoretical Explanation ◽  
Thermophilic Bacterium ◽  
Optimum Growth ◽  
Optimum Growth Temperature ◽  
Irreversible Denaturation ◽  
Temperature Ranges ◽  
Effects Of Temperature ◽  
Lower Temperature

The effects of temperature on the kinetic parameters kcat and Km, for three isolates of the highly conserved monomeric enzyme 3-phosphoglycerate kinase (PGK), were investigated in detail using a rapid automated kinetics apparatus. PGK was purified from the thermophilic bacterium Thermoanaerobacter sp. Rt8.G4 (optimum growth temperature 68 °C), the mesophile Zymomonas mobilis (optimum growth temperature 32 °C) and a second, unidentified, soil mesophile designated unid A (optimum growth temperature 27 °C). The kinetic behaviour with temperature of each PGK preparation was distinct, despite the conserved nature of the enzyme. The kcat values increased with temperature, but not as rapidly exponentially, as might be expected from the Arrhenius equation. Maximum kcat values were at much higher temperatures than the optimum growth temperatures for the mesophiles, but for the thermophile the temperature of maximum kcat was close to its optimum growth temperature. Km values were in general nearly constant through the lower temperature ranges, but increased substantially as the optimum temperature (highest kcat) was passed. Thermal irreversible denaturation of the PGK proteins was also investigated by measuring loss of activity over time. In a dilute buffer, Arrhenius plots for denaturation were linear, and the calculated apparent energy of activation (Eact) for denaturation for the thermophilic PGK was 600 kJ·mol-1, whereas for the mesophilic enzymes the values were 200-250 kJ·mol-1. In the presence of substrates, a considerable stabilization occurred, and in the case of the Z. mobilis enzyme, the apparent Eact was increased to 480 kJ·mol-1. A theoretical explanation for these observations is presented. Comparing the kinetics data with irreversible denaturation rates determined at relevant temperatures, it was clear that kcat values reached a maximum, and then decreased with higher temperature before irreversible denaturation had any significant influence.

Interpretation of Some Terms and Phrases in Public Weather Forecasts

1983 ◽  
Vol 64 (11) ◽  
pp. 1283-1289 ◽  
Author(s):  
Allan H. Murphy ◽  
Barbara G. Brown
Keyword(s):  
Undergraduate Students ◽  
Temporal Variations ◽  
Public Understanding ◽  
State University ◽  
Primitive Form ◽  
Weather Forecasts ◽  
Temperature Ranges ◽  
Future Work ◽  
Oregon State University ◽  
Temporal Modifiers

This paper reports some results of a study in which two groups of individuals—undergraduate students and professional meteorologists at Oregon State University—completed a short questionnaire concerning their interpretations of terminology commonly used in public weather forecasts. The questions related to terms and phrases associated with three elements: 1) cloudiness—fraction of sky cover; 2) precipitation—spatial and/or temporal variations; and 3) temperature—specification of intervals. The students' responses indicate that cloudiness terms are subject to wide and overlapping ranges of interpretation, although the interpretations of these terms correspond quite well to National Weather Service definitions. Their responses to the precipitation and temperature questions reveal that some confusion exists concerning the meaning of spatial and temporal modifiers in precipitation forecasts and that some individuals interpret temperature ranges in terms of asymmetric intervals. When compared to the students' responses, the meteorologists' responses exhibit narrower ranges of interpretation of the cloudiness terms and less confusion about the meaning of spatial/temporal precipitation modifiers. The study was not intended to be a definitive analysis of public understanding of forecast terminology. Instead, it should be viewed as a primitive form of the type of forecast-terminology study that must be undertaken in the future. Some implications of this investigation for future work in the area are discussed briefly.

Large Water‐Hammer Pressures for Column Separation in Pipelines

1991 ◽  
Vol 117 (10) ◽  
pp. 1310-1316 ◽  
Author(s):  
Angus R. Simpson ◽  
E. Benjamin Wylie
Keyword(s):  
Water Hammer ◽  
Column Separation ◽  
Large Water
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