scholarly journals Method of estimating the effective zone induced by rapid impact compaction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shih-Hao Cheng ◽  
Shi-Shuenn Chen ◽  
Louis Ge
Keyword(s):  
Propagation Distance ◽  
Effective Range ◽  
Normal Distribution Function ◽  
Peak Acceleration ◽  
Frequent Use ◽  
Peak Over Threshold ◽  
Effective Depth ◽  
The Mean ◽  
Rapid Impact Compaction ◽  
Compaction Degree

AbstractThis paper proposes a method for estimating the effective zone, including effective depth and effective range of compaction degree, from rapid impact compaction (RIC) on sand layer whose fines content is less than 10%. The proposed method utilizes a string of microelectromechanical system accelerometers to monitor the acceleration at various depths and propagation distances during compaction. To interpret and extract useful information from monitored data, peak-over-threshold (POT) processing and normal distribution function were used to analyze the recorded acceleration. The mean and standard deviation of the threshold peak acceleration were used to evaluate the effective depth and the effective range of compaction degree during RIC compaction. Moreover, spatial contours were used to determine the correlation of the threshold peak acceleration against depth and propagation distance from the RIC impact point. These contours help indicating the distribution of the effect zone after compaction. Lastly, a proposed method is suggested for frequent use in trial tests to quickly determine RIC’s required depth and impact spacing.

scholarly journals Comparison of branded rugby headguards on their effectiveness in reducing impact on the head

2018 ◽  
Vol 4 (1) ◽  
pp. e000361 ◽  
Author(s):  
Erin R A Frizzell ◽  
Graham P Arnold ◽  
Weijie Wang ◽  
Rami J Abboud ◽  
Tim S Drew
Keyword(s):  
Impact Force ◽  
Linear Acceleration ◽  
Baseline Measurement ◽  
Peak Acceleration ◽  
Impact Forces ◽  
Impact Attenuation ◽  
The Mean ◽  
Force Reduction ◽  
The Right ◽  
The Impact

AimTo compare the available brands of rugby headguards and evaluate their impact attenuation properties at various locations on the cranium, with regard to concussion prevention.MethodsSeven different branded headguards were fitted onto a rigid headform and drop-tested in three different positions. An accelerometer measured the linear acceleration the headform experienced on impact with the ground. Each test involved dropping the headform from a height that generated 103.8 g on average when bare, which is the closest acceleration to the upper limit of the concussion threshold of 100 g. A mean peak acceleration for each drop position was calculated and compared with the bare baseline measurement.ResultsEach headguard demonstrated a significant decrease in the mean peak acceleration from the baseline value (all p≤0.01). Overall the Canterbury Ventilator was the most effective headguard, decreasing the impact force on average by 47%. The least effective was the XBlades Elite headguard, averaging a force reduction of 27%. In five of the seven headguards, the right side of the headwear was the most effective at reducing impact force.ConclusionOverall, the results indicate that it would be beneficial to wear a headguard during rugby in order to reduce the impact forces involved in head collisions. There was also a clear difference in performance between the tested brands, establishing the Canterbury headguard as the most effective. However, only one model of headguard from each brand was tested, so further research evaluating all other models should be considered.

scholarly journals Activity patterns of South American silver catfish (Rhamdia quelen)

2006 ◽  
Vol 66 (2a) ◽  
pp. 565-574 ◽  
Author(s):  
U. H. Schulz ◽  
C. Leuchtenberger
Keyword(s):  
Woody Debris ◽  
Activity Patterns ◽  
Swimming Activity ◽  
Fish Length ◽  
South American ◽  
Silver Catfish ◽  
Frequent Use ◽  
Rhamdia Quelen ◽  
Lakes And Reservoirs ◽  
The Mean

The South American silver catfish (Rhamdia quelen) is a widely distributed species in Central and South America in areas east of the Andes between Venezuela and the northern parts of Argentina. The bottom dwelling species occurs in lakes and reservoirs as well as in rivers. Between June 2000 and December 2001, sixteen silver catfish were tracked during fourteen 24-h cycles in two-hour-intervals, with the aim of investigating daily movements and habitat use. Covered distances varied between 0 m/2 h and 326 m/2 h and the mean distance covered in 2 h was 25.6 m. The mean activity of individual silver catfish varied between 5.6 m/2 h and 81.4 m/2 h. The swimming activity was linearly related to the total fish length. The highest mean swimming activity occurred in the morning and at nightfall. Silver catfish concentrated in three areas of frequent use. All of them were characterized by steep banks providing shelter in the form of rip-rap or large woody debris. Vertically, silver catfish preferred the upper 2 m layer where tracked fish encountered higher temperatures and higher dissolved oxygen concentrations.

scholarly journals Evaluation of jet grout column diameters by acoustic monitoring

2017 ◽  
Vol 54 (12) ◽  
pp. 1781-1789 ◽  
Author(s):  
Shih-Hao Cheng ◽  
Hung-Jiun Liao ◽  
Junichi Yamazaki ◽  
Ricky K.N. Wong
Keyword(s):  
Acoustic Monitoring ◽  
Effective Diameter ◽  
Normal Distribution Function ◽  
Monitoring Method ◽  
The Past ◽  
Frequent Use ◽  
Dimension Measurement ◽  
Jet Grouting ◽  
Gravelly Soil ◽  
Jet Nozzle

To evaluate the diameter of jet grout columns actually formed under the ground, several methods had been developed over the past years. Nevertheless, uncertainty still exists in different methods mostly due to the variations of ground and grouting conditions. This study proposes an acoustic monitoring system capable of directly recording the jet grouting sounds detected at different distances from the jet nozzle. To correlate the actual diameter of the jet grout column with the monitored sound prints, a field test was conducted in an interlayered sandy and gravelly soil and the jet grout column was excavated for dimension measurement. The recorded sounds show that the distribution of the threshold peak amplitudes at different distances can be represented by the curve of the normal distribution function. In addition, the standard deviation and mean of the normally distributed threshold peak amplitudes can be used as indicators to determine the effective diameter of the jet grout column for a specific jet grouting project. Although this acoustic monitoring method would be costly and time-consuming if used to examine all jet grout columns, it is suitable for frequent use in trial tests for finding reasonable grouting parameters when forming jet grout columns with design diameters.

scholarly journals Research on Intelligent Compaction Technology of Subgrade Based on Regression Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Ziyi Hou ◽  
Xiao Dang ◽  
Yezhen Yuan ◽  
Bo Tian ◽  
Sili Li
Keyword(s):  
Resilient Modulus ◽  
Single Point ◽  
Mean Value ◽  
Test Results ◽  
Intelligent Compaction ◽  
One Dimensional ◽  
Remote Monitoring System ◽  
The Mean ◽  
The One ◽  
Compaction Degree

A remote monitoring system with the intelligent compaction index CMV as the core is designed and developed to address the shortcomings of traditional subgrade compaction quality evaluation methods. Based on the actual project, the correlation between the CMV and conventional compaction indexes of compaction degree K and dynamic resilient modulus E is investigated by applying the one-dimensional linear regression equation for three types of subgrade fillers, clayey gravel, pulverized gravel, and soil-rock mixed fill, and the scheme of fitting CMV to the mean value of conventional indexes is adopted, which is compared with the scheme of fitting CMV to the single point of conventional indexes in the existing specification. The test results show that the correlation between the CMV and conventional indexes of clayey gravel and pulverized gravel is much stronger than that of soil-rock mixed subgrades, and the correlation coefficient can be significantly improved by fitting CMV to the mean of conventional indexes compared with single-point fitting, which can be considered as a new method for intelligent rolling correlation verification.

scholarly journals Evaluation of the Development of Tolerance Following Frequent Administration of Propofol in Children Requiring Successive Sedation for Separate Procedures

2021 ◽  
Vol 26 (3) ◽  
pp. 277-283
Author(s):  
Nadia Shaikh ◽  
Brandon Tallman ◽  
Yanzhi Wang ◽  
Girish Deshpande ◽  
Sandeep Tripathi
Keyword(s):  
Mixed Model ◽  
Retrospective Chart Review ◽  
Time Interval ◽  
Induction Dose ◽  
Frequent Use ◽  
Frequent Administration ◽  
Short Period ◽  
Repeated Administrations ◽  
The Mean ◽  
Development Of Tolerance

OBJECTIVE Propofol is frequently used for outpatient sedation for pediatric patients, some of whom require multiple rounds of sedation for separate procedures within a short period. Anecdotal experience suggests that frequent use of propofol results in escalating doses; however, clinical evidence is unconvincing. This study was designed to evaluate if tolerance develops with frequent administration of propofol for children requiring multiple successive sedations. METHODS A retrospective chart review of patients requiring multiple doses of propofol for separate procedures from 2011 through 2019 was conducted. Cumulative propofol dose and induction dose were analyzed using a mixed model for patients requiring sedation for serial procedures. RESULTS Data from 24 different patients who required 3 or more sedations during the study period were analyzed. The number of sedations ranged from 3 to 28. The mean total propofol dose rate was 0.19 ± 0.14 mg/kg/min, and the mean induction dose was 3.2 ± 0.97 mg/kg. The total doses and induction doses were not statistically significantly different at different sedations (p = 0.089 and 0.180, respectively). There was a statistically significant decrease in the total dose as the time interval between 2 sedations increased (p < 0.001). CONCLUSIONS Repeated administrations of propofol at time intervals used in outpatient sedation do not lead to the development of tolerance. A small decrease per day interval may be significant when propofol is used more frequently (multiple times per day or as a continuous drip) in an ICU setting.

scholarly journals Near-Surface Current Mapping by Shipboard Marine X-Band Radar: A Validation

2018 ◽  
Vol 35 (5) ◽  
pp. 1077-1090 ◽  
Author(s):  
Björn Lund ◽  
Brian K. Haus ◽  
Jochen Horstmann ◽  
Hans C. Graber ◽  
Ruben Carrasco ◽  
...  
Keyword(s):  
Mississippi River ◽  
Oil Spills ◽  
Surface Current ◽  
Current Profile ◽  
Near Surface ◽  
Sea Surface Roughness ◽  
X Band ◽  
Effective Depth ◽  
The Mean ◽  
Potential Impact

AbstractThe Lagrangian Submesoscale Experiment (LASER) involved the deployment of ~1000 biodegradable GPS-tracked Consortium for Advanced Research on Transport of Hydrocarbon in the Environment (CARTHE) drifters to measure submesoscale upper-ocean currents and their potential impact on oil spills. The experiment was conducted from January to February 2016 in the Gulf of Mexico (GoM) near the mouth of the Mississippi River, an area characterized by strong submesoscale currents. A Helmholtz-Zentrum Geesthacht (HZG) marine X-band radar (MR) on board the R/V F. G. Walton Smith was used to locate fronts and eddies by their sea surface roughness signatures. The MR data were further processed to yield near-surface current maps at ~500-m resolution up to a maximum range of ~3 km. This study employs the drifter measurements to perform the first comprehensive validation of MR near-surface current maps. For a total of 4130 MR–drifter pairs, the root-mean-square error for the current speed is 4 cm and that for the current direction is 12°. The MR samples currents at a greater effective depth than the CARTHE drifters (1–5 m vs ~0.4 m). The mean MR–drifter differences are consistent with a wave- and wind-driven vertical current profile that weakens with increasing depth and rotates clockwise from the wind direction (by 0.7% of the wind speed and 15°). The technique presented here has great potential in observational oceanography, as it allows research vessels to map the horizontal flow structure, complementing the vertical profiles measured by ADCP.

scholarly journals Interpretation of CBR Test Results Based on the Rapid Impact Compaction Electro-Mechanic System Model

2018 ◽  
Vol 203 ◽  
pp. 04003
Author(s):  
Arifin Beddu ◽  
Lawalenna Samang ◽  
Tri Harianto ◽  
Achmad Bakri Muhiddin
Keyword(s):  
Energy Level ◽  
Energy Levels ◽  
Test Results ◽  
New Development ◽  
Cbr Test ◽  
Compaction Processes ◽  
Rapid Impact Compaction ◽  
Cylindrical Test ◽  
Compaction Degree ◽  
Construction Works

In order to understand the mechanical properties of the compaction results and to optimize the relevant energy design of the repeated Rapid Impact Compaction (RIC), a series of California Bearing Ratio (CBR) tests were performed on the compaction sample with RIC electro-mechanic system. In this laboratory test, samples were compacted at various RIC impact energy levels. A mass of different weight and various of falling height was used to compact the samples in a CBR cylindrical test. The mass was repeatedly dropped on the anvil plate with a frequency of 30-40 blows per minute. The compaction process carried out by varying number of blows from 5 to 35 for each compacted sample, and all compaction processes were controlled by electro-mechanic new development system. The test results represented that there was a variation of CBR value at the same RIC energy levels. The CBR values at the same energy level with the larger number of blow increased higher in lighter mass, whereas than the RIC energy level for larger masses with the smaller number of blows also occurred with the same trend to the result of relative compaction density test. This advantages that with a better understanding of RIC mechanisms and relevant energy designs, it is a new practical idea to improve compaction degree as well as CBR value on fill construction works with appropriate equipment and lower energy consumption.

scholarly journals Effects of urban street spatial parameters on sound propagation

2017 ◽  
Vol 46 (2) ◽  
pp. 341-358 ◽  
Author(s):  
Wu Hupeng ◽  
Jian Kang ◽  
Jin Hong
Keyword(s):  
Decay Time ◽  
Sound Propagation ◽  
Propagation Distance ◽  
Reverberation Time ◽  
Cross Sectional ◽  
Urban Street ◽  
Near Zone ◽  
Lane Width ◽  
Spatial Parameters ◽  
The Mean

Many studies have demonstrated that the effect of urban street spatial shape on sound propagation cannot be ignored. Most previous studies are based on idealised spatial models and but not systematically and comprehensively examine the real and complex street space. This paper takes the actual streets of a high-density city as research objects, select reliable spatial parameters, obtain the acoustic propagation data using computer simulation, identify the sound propagation characteristics and establish sound propagation models of urban streets. In total, 144 samples have been tested, 13 spatial parameters, including the width information, height information, section information and plan information of streets, have been selected, and three acoustic indices, which include the sound attenuation, reverberation time and early decay time, have been analysed in this paper. The sound propagation in the urban street is consistent with the propagation characteristics of the semi-free sound field, i.e. the sound attenuation is linearly correlated with the logarithm of the sound propagation distance. This linear correlation becomes more pronounced for the greater Plan enclosure degree and more even distribution of façades. The trend of sound attenuations decreases with the increasing Cross-sectional enclosure degree, increasing Plan enclosure degree in the Near Zone or decreasing Vehicle lane width. Reverberation time is primarily distributed between 1.0 s and 3.0 s and tends to be stable when the propagation distance increases. The mean reverberation time increases with the increasing Mean façade height, Sidewalk width, Cross-sectional enclosure degree in the Near Zone or Standard deviation of Plan enclosure degree in the Near Zone. The typical early decay time distribution curve is clearly divided into two areas along the propagation direction. In the first area, the early decay time value is notably small and nearly equals zero. With a sudden increase, the early decay time maintains at a relatively stable value in the second area (stable area) of 0 to 3.0 s. The mean early decay time in the stable area increases with the increasing Vehicle lane width, increasing Cross-sectional enclosure degree or decreasing Standard deviation of Plan enclosure degree in the Near Zone.

Approximating the Normal Sample Median Distribution in Process Control

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Char Leung
Keyword(s):  
Process Control ◽  
Small Samples ◽  
Normal Sample ◽  
Normal Distribution Function ◽  
Engineering Process ◽  
Sample Median ◽  
Central Tendency Measure ◽  
Engineering Process Control ◽  
Large Samples ◽  
The Mean

Abstract The present work aims to propose an approximation of the sample median distribution with a normal parent distribution. Although the mean is usually used as the central tendency measure for normal samples, the median has also been used in engineering, process control in particular. The proposed method approximates the normal sample median distribution only using the normal distribution function. It outperforms Castagliola’s method for small samples and serves as an alternative approximation for trading off accuracy against computational complexity for large samples.

Estimation of the peak horizontal ground acceleration based on peak accelerations of the components

1982 ◽  
Vol 72 (2) ◽  
pp. 637-642
Author(s):  
N. Mostaghel ◽  
G. Ahmadi
Keyword(s):  
Standard Deviation ◽  
Ground Motion ◽  
Mean Value ◽  
Peak Acceleration ◽  
Lower And Upper Bounds ◽  
Ground Acceleration ◽  
Standard Deviation Estimate ◽  
Orthogonal Components ◽  
Deviation Estimate ◽  
The Mean

Abstract Lower and upper bounds of the peak horizontal ground acceleration are obtained through the consideration of the peak accelerations of two horizontal orthogonal components of the ground motion. Since the bounded region is relatively narrow, it is proposed to use the mean of the upper and lower bound accelerations as the peak horizontal ground acceleration. This mean value is equal to 1.20 times the larger peak acceleration of the two horizontal components of the ground motion. To support the proposed value, a simplified statistical analysis is also employed which results in a mean plus one standard deviation value for the peak horizontal ground acceleration of 1.24 times the larger peak acceleration. These conclusions are also supported by comparison with 50 pairs of earthquake acceleration records. For the resultant acceleration, the 50 pairs of records yield a mean plus one standard deviation estimate of the order of 1.20 times the larger peak acceleration.

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