scholarly journals The square root method for chloride ingress prediction—Applicability and limitations

2021 ◽  
Vol 54 (2) ◽  
Author(s):  
Simon Fjendbo ◽  
Henrik E. Sørensen ◽  
Klaartje De Weerdt ◽  
Mette R. Geiker
Keyword(s):  
Recent Observation ◽  
Chloride Concentration ◽  
Chloride Ingress ◽  
Square Root ◽  
Granulated Blast Furnace Slag ◽  
Reference Concentration ◽  
Straight Line ◽  
Fixed Reference ◽  
The Baltic ◽  
Square Root Method

AbstractA recent observation showed a square root time dependency of the ingress depth of a fixed (reference) chloride concentration of 0.05% chloride by mass of concrete for submerged exposure in Kattegat and the Baltic Sea. The purpose of this paper is to assess the applicability and limitations of the observation, widen the scope of validity and propose it as a method. Field data from submerged, tidal, splash, atmospheric and inland deicing salt exposure at various geographical locations was analyzed at a range of reference concentrations. In total 237 combinations of concrete, exposure, and reference concentration were analyzed. Our results showed that chloride ingress of a reference concentration followed a linear relationship with an average R2 of 0.96, when the penetration depth of the reference concentration was plotted against the square root of the exposure time. The square root observation appeared valid for the studied Portland cement based concretes with fly ash, silica fume and ground granulated blast furnace slag exposed in submerged and tidal exposure zones, when applying reference concentrations of 0.1–1.8% chloride by mass of binder, and reference concentrations of 0.1–0.5% chloride by mass of binder in atmospheric exposure zone. It was found that the parameters describing the straight line depended on the chosen reference concentration and concrete composition, and that the slope of the straight line (ingress parameter) in addition depended on the exposure. It was concluded that the square root method appears to be a promising method for predicting further chloride ingress into concrete.

scholarly journals Controlling Shipping Along the North European Trade Axis

1971 ◽  
Vol 24 (4) ◽  
pp. 553-556
Author(s):  
D. J. Lindsay
Keyword(s):  
Weather Conditions ◽  
North Coast ◽  
Baltic Basin ◽  
Long Distance ◽  
The North ◽  
Large Numbers ◽  
Straight Line ◽  
European Trade ◽  
Trade Route ◽  
The Baltic

By the North European Trade Axis is meant the trade route from Ushant and Land's End, up the English Channel, through the Dover Strait fanning out to serve eastern England, the north coast of continental Europe and leading to the Baltic Basin. Recent events in this area have left a feeling that some form of tightening of control is not only desirable, but is rapidly becoming imperative. There is a basic conflict between the two forms of shipping using the area: the local users who use the area more or less constantly, and the long-distance traders, usually much larger, which arrive in the area for a brief stay after a prolonged period at sea, which has usually been in good weather conditions. Frequently these latter ships have a very poor notion of the hornet's nest into which they are steaming when they arrive. The net result is all too often the same: the local users, with familiarity breeding contempt, wander about as they see fit, with scant regard for routing or the regulations; all too often the big ships arrive from sea with navigating staffs who are too confused, sometimes too ignorant—and sometimes too terrified—to do much more than blunder forward in a straight line hoping for the best. Quite obviously this is not a total picture, and there are large numbers of ships which navigate perfectly competently, but the minority of those which do not seem to be rising rapidly, and show every sign of continuing to increase.

Modified Square Root Method of Matrix Inversion

Technometrics ◽  
1962 ◽  
Vol 4 (2) ◽  
pp. 282-287 ◽  
Author(s):  
A. E. Sarhan ◽  
B. G. Greenberg ◽  
Eleanor Rorerts
Keyword(s):  
Matrix Inversion ◽  
Square Root ◽  
Square Root Method

scholarly journals Impact of a Vibrotactile Belt on Emotionally Challenging Everyday Situations of the Blind

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7384
Author(s):  
Charlotte Brandebusemeyer ◽  
Anna Ricarda Luther ◽  
Sabine U. König ◽  
Peter König ◽  
Silke M. Kärcher
Keyword(s):  
Emotional Impact ◽  
Vibrotactile Stimulation ◽  
Angular Rotation ◽  
Straight Line ◽  
Before And After ◽  
Fixed Reference ◽  
Behavioural Experiments ◽  
Triangle Completion ◽  
Subjective Discomfort ◽  
Magnetic North

Spatial orientation and navigation depend primarily on vision. Blind people lack this critical source of information. To facilitate wayfinding and to increase the feeling of safety for these people, the “feelSpace belt” was developed. The belt signals magnetic north as a fixed reference frame via vibrotactile stimulation. This study investigates the effect of the belt on typical orientation and navigation tasks and evaluates the emotional impact. Eleven blind subjects wore the belt daily for seven weeks. Before, during and after the study period, they filled in questionnaires to document their experiences. A small sub-group of the subjects took part in behavioural experiments before and after four weeks of training, i.e., a straight-line walking task to evaluate the belt’s effect on keeping a straight heading, an angular rotation task to examine effects on egocentric orientation, and a triangle completion navigation task to test the ability to take shortcuts. The belt reduced subjective discomfort and increased confidence during navigation. Additionally, the participants felt safer wearing the belt in various outdoor situations. Furthermore, the behavioural tasks point towards an intuitive comprehension of the belt. Altogether, the blind participants benefited from the vibrotactile belt as an assistive technology in challenging everyday situations.

scholarly journals Effect of the Addition of GGBS on the Frost Scaling and Chloride Migration Resistance of Concrete

2020 ◽  
Vol 10 (11) ◽  
pp. 3940
Author(s):  
Vera Correia ◽  
João Gomes Ferreira ◽  
Luping Tang ◽  
Anders Lindvall
Keyword(s):  
Blast Furnace Slag ◽  
Curing Temperature ◽  
Special Focus ◽  
Chloride Ingress ◽  
Air Content ◽  
Granulated Blast Furnace Slag ◽  
Chloride Migration ◽  
Migration Resistance ◽  
Efficiency Factors ◽  
Furnace Slag

Ground Granulated Blast-furnace Slag (GGBS) can partially replace cement in concrete to improve certain properties. However, some concerns regarding its performance have been raised. This research aimed at investigating the properties of concrete with GGBS, with special focus on its frost scaling and chloride ingress resistance. Concretes with different amounts of GGBS, different efficiency factors, and different air contents have been tested. The effects of other factors, namely the curing temperature, the use of superplasticizer and carbonation, have also been investigated. The results showed that the frost resistance generally decreases with the increase of the amount of GGBS. However, this research showed that it is possible to produce frost resistant concrete with up to 50% of GGBS by changing some properties of the mix (such as increasing the air content). The results also showed a significant improvement of the chloride ingress resistance for concrete with high additions of GGBS.

A quantitative measure of nonlinearity

1993 ◽  
Vol 39 (5) ◽  
pp. 766-772 ◽  
Author(s):  
K Emancipator ◽  
M H Kroll
Keyword(s):  
Analytical Method ◽  
Response Curve ◽  
Polynomial Regression ◽  
Quantitative Measure ◽  
Square Root ◽  
Straight Line ◽  
The Mean ◽  
The Difference ◽  
Definition Of ◽  
Fitting In

Abstract Quantitative measures of the nonlinearity of an analytical method are defined as follows: the "(dimensional) nonlinearity" of a method is the square root of the mean of the square of the deviation of the response curve from a straight line, where the straight line is chosen to minimize the nonlinearity. The "relative nonlinearity" is defined as the dimensional nonlinearity divided by the difference between the maximum and minimum assayed values. These definitions may be used to develop practical criteria for linearity that are still objective. Calculation of the nonlinearity requires a method of curve-fitting. In this article, we use polynomial regression to demonstrate calculations, but the definition of nonlinearity also accommodates alternative nonlinear regression procedures.

A New Analytical Method for Analyzing Linear Flow in Tight/Shale Gas Reservoirs: Constant-Flowing-Pressure Boundary Condition

2012 ◽  
Vol 15 (03) ◽  
pp. 370-384 ◽  
Author(s):  
Morteza Nobakht ◽  
C.R.. R. Clarkson
Keyword(s):  
Shale Gas ◽  
Analytical Method ◽  
Flow Analysis ◽  
Initial Pressure ◽  
Reliable Estimate ◽  
Square Root ◽  
Linear Flow ◽  
Straight Line ◽  
Half Length ◽  
Time Plot

Summary Many tight/shale gas wells exhibit linear flow, which can last for several years. Linear flow can be analyzed using a square-root-of-time plot, a plot of rate-normalized pressure vs. the square root of time. Linear flow appears as a straight line on this plot, and the slope of this line can be used to calculate the product of fracture half-length and the square root of permeability. In this paper, linear flow from a fractured well in a tight/shale gas reservoir under a constant-flowing-pressure constraint is studied. It is shown that the slope of the square-root-of-time plot results in an overestimation of fracture half-length, if permeability is known. The degree of this overestimation is influenced by initial pressure, flowing pressure, and formation compressibility. An analytical method is presented to correct the slope of the square-root-of-time plot to improve the overestimation of fracture halflength. The method is validated using a number of numerically simulated cases. As expected, the square-root-of-time plots for these simulated cases appear as a straight line during linear flow for constant flowing pressure. It is found that the newly developed analytical method results in a more reliable estimate of fracture half-length, if permeability is known. Our approach, which is fully analytical, results in an improvement in linear-flow analysis over previously presented methods. Finally, the application of this method to multifractured horizontal wells is discussed and the method is applied to three field examples.

Field calibration of a soil sulfate test on sward lucerne on the eastern Darling Downs, Queensland

1981 ◽  
Vol 21 (110) ◽  
pp. 303 ◽  
Author(s):  
PJ White ◽  
MJ Whitehouse ◽  
LA Warrell ◽  
PR Burrill
Keyword(s):  
Soil Water ◽  
Chloride Concentration ◽  
Relative Yield ◽  
Quadratic Model ◽  
Square Root ◽  
Relative Importance ◽  
Water Suspension ◽  
Field Calibration ◽  
Best Fit ◽  
Soil Level

The relation between phosphate-extractable sulfate and the response of lucerne to applied sulfur was examined on 20 established lucerne (Medicago sativa) swards on the black earths of the Darling Downs. Two rates of S were used (0.100 kg ha-1) and soil depths to 90 cm were considered. Six sites responded at the first cut and relative yield of lucerne was correlated with soil sulfate. The best fit of the data was obtained using a square root quadratic model and sulfate in the 0-80 cm zone. The critical soil level was 3.5 ppm. Of 17 attributes examined, only chloride concentration (0-60 cm) and conductivity of the soil water suspension (0-60 cm) significantly improved the variance in relative yield explained, but this was considered to be fortuitous. The relative importance of sub-soil sulfate (40-80 cm) to lucerne nutrition on these soils is shown.

Dynamic Modeling and Analysis of a Two D.O.F. Mobile Manipulator

2000 ◽  
Author(s):  
D. Naderi ◽  
A. Meghdari ◽  
M. Durali
Keyword(s):  
Dynamic Modeling ◽  
Degrees Of Freedom ◽  
Ground Surface ◽  
Mobile Manipulator ◽  
Two Degrees Of Freedom ◽  
Modeling And Analysis ◽  
Straight Line ◽  
Fixed Reference ◽  
Line Trajectory ◽  
Straight Line Trajectory

Abstract This paper presents the kinematic and dynamic modeling of a two degrees of freedom manipulator attached to a vehicle with a two degrees of freedom suspension system. The vehicle is considered to move with a constant linear speed over an irregular ground-surface while the end-effector tracks a desired trajectory in a fixed reference frame. In addition, the effects of highly coupled dynamic interaction between the manipulator and vehicle (including the suspension system’s effects) have been studied. Finally, simulation results for the end-effector’s straight-line trajectory are presented to illustrate these effects.

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