scholarly journals Comparison of Buoy-Mounted and Bottom-Moored ADCP Performance at Gray’s Reef

2007 ◽  
Vol 24 (2) ◽  
pp. 270-284 ◽  
Author(s):  
Harvey E. Seim ◽  
Catherine R. Edwards
Keyword(s):  
High Frequency ◽  
Major Axis ◽  
National Data ◽  
Noise Floor ◽  
The North ◽  
Experimental Configuration ◽  
Adcp Measurements ◽  
Adcp Data ◽  
Adcp Observations ◽  
East West

Abstract Simultaneous ADCP profile measurements are compared over a 2-month period in late 2003. One set of measurements comes from a National Data Buoy Center (NDBC) buoy-mounted ADCP, the other from a bottom-mounted, upward-looking ADCP moored roughly 500 m from the buoy. The study was undertaken to evaluate the proficiency of an experimental configuration by NDBC; unfortunately, the ADCP was not optimally configured. The higher temporally and vertically resolved bottom-mounted ADCP data are interpolated in time and depth to match the buoy-mounted ADCP measurements. It is found that the two ADCP measurements are significantly different. The buoy-mounted measurements are affected by high-frequency (<10 h period) noise that is vertically coherent throughout the profiles. This noise results in autospectra that are essentially white, unlike the classic red spectra formed from the bottom-mounted ADCP observations. The spectra imply a practical noise floor of 0.045 m s−1 for the buoy-mounted system. Contamination by surface waves is the likely cause of this problem. At tidal frequencies the buoy-mounted system underestimates major axis tidal current magnitude by 10%–40%; interference from the buoy chain and/or fish or plankton are considered the most likely cause of the bias. The subtidal velocity field (periods greater than 40 h) is only partially captured; the correlation coefficient for the east–west current is 0.49 and for the north–south current is 0.64.

The tombs of burial mound No. 49 of the Han Dynasty at Shangma Hill in Anji County, Zhejiang Province

2016 ◽  
Vol 16 (1) ◽  
pp. 119-133
Keyword(s):  
Major Axis ◽  
Han Dynasty ◽  
Burial Mound ◽  
Western Han Dynasty ◽  
The North ◽  
Ancient City ◽  
Fine Clay ◽  
Zhejiang Provincial ◽  
East West ◽  
Grave Goods

Abstract In 2008, Zhejiang Provincial Institute of Cultural Relics and Archaeology excavated the burial mound No. 49 (D49) in the Shangma Hill Cemetery located at Liangpeng Town, Anji County. D49 was an earthen mound in oval plan, the major axis of which was in north-south orientation. In this mound, six tombs were recovered, all of which were earthen shaft pit tombs with wooden coffin chambers, one of which had two coffins and the rest all had single coffin. These tombs had two kinds of orientation: the east-west and the north-south. One of them had passage and the rest did not. The grave goods were pottery wares, jades, bronzes, iron objects, stone implements and glass objects; the pottery wares were composed of glazed pottery wares, hard pottery wares and fine clay pottery wares, etc. The grave goods showed that the dates of these six tombs were the mid and late Western Han Dynasty, and their regular arrangement hinted that their occupants had close relationships; referring to the historic literature, the excavators inferred that the D49 was a family cemetery. The excavation of Shangma Hill Cemetery is deeply meaningful for the comprehensive research on the Anji ancient city and the confirmation of its nature.

scholarly journals A Low frequency Southern Sky Survey Using the Mauritius Radio Telescope

2002 ◽  
Vol 199 ◽  
pp. 25-31
Author(s):  
N. Udaya Shankar
Keyword(s):  
Radio Telescope ◽  
Low Frequency ◽  
Fourier Synthesis ◽  
North East ◽  
The North ◽  
Sky Survey ◽  
Correlation Receiver ◽  
Complex Correlation ◽  
Right Ascension ◽  
East West

The Mauritius Radio Telescope (MRT) is a Fourier synthesis instrument which has been built to fill the gap in the availability of deep sky surveys at low radio frequencies in the southern hemisphere. It is situated in the north-east of Mauritius at a southern latitude of 20°.14 and an eastern longitude of 57°.73. The aim of the survey with the MRT is to contribute to the database of southern sky sources in the declination range −70° ≤ δ ≤ −10°, covering the entire 24 hours of right ascension, with a resolution of 4' × 4'.6sec(δ + 20.14°) and a point source sensitivity of 200 mJy (3σ level) at 151.5 MHz.MRT is a T-shaped non-coplanar array consisting of a 2048 m long East-West arm and a 880 m long South arm. In the East-West arm 1024 fixed helices are arranged in 32 groups and in the South arm 16 trolleys, with four helices on each, which move on a rail are used. A 512 channel, 2-bit 3-level complex correlation receiver is used to measure the visibility function. At least 60 days of observing are required for obtaining the visibilities up to the 880 m spacing. The calibrated visibilities are transformed taking care of the non-coplanarity of the array to produce an image of the area of the sky under observation.This paper will describe the telescope, the observations carried out so far, a few interesting aspects of imaging with this non-coplanar array and present results of a low resolution survey (13' × 18') covering roughly 12 hours of right ascension, and also present an image with a resolution of 4' × 4'.6sec(δ + 20.14°) made using the telescope.

scholarly journals Optimal design of the solar tracking system of parabolic trough concentrating collectors

2020 ◽  
Vol 15 (4) ◽  
pp. 613-619
Author(s):  
Li Kong ◽  
Yunpeng Zhang ◽  
Zhijian Lin ◽  
Zhongzhu Qiu ◽  
Chunying Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Radiation ◽  
Tracking System ◽  
Low Cost ◽  
Parabolic Trough ◽  
The North ◽  
Tracking Mode ◽  
Solar Tracking ◽  
East West

Abstract The present work aimed to select the optimum solar tracking mode for parabolic trough concentrating collectors using numerical simulation. The current work involved: (1) the calculation of daily solar radiation on the Earth’s surface, (2) the comparison of annual direct solar radiation received under different tracking modes and (3) the determination of optimum tilt angle for the north-south tilt tracking mode. It was found that the order of solar radiation received in Shanghai under the available tracking modes was: dual-axis tracking > north-south Earth’s axis tracking > north-south tilt tracking (β = 15°) > north-south tilt tracking (β = 45) > north-south horizontal tracking > east-west horizontal tracking. Single-axis solar tracking modes feature simple structures and low cost. This study also found that the solar radiation received under the north-south tilt tracking mode was higher than that of the north-south Earth’s axis tracking mode in 7 out of 12 months. Therefore, the north-south tilt tracking mode was studied separately to determine the corresponding optimum tilt angles in Haikou, Lhasa, Shanghai, Beijing and Hohhot, respectively, which were shown as follows: 18.81°, 27.29°, 28.67°, 36.21° and 37.97°.

High-Frequency Radar Mapping of Surface Currents Using WERA

2007 ◽  
Vol 24 (3) ◽  
pp. 484-503 ◽  
Author(s):  
Lynn K. Shay ◽  
Jorge Martinez-Pedraja ◽  
Thomas M. Cook ◽  
Brian K. Haus ◽  
Robert H. Weisberg
Keyword(s):  
Time Series ◽  
High Frequency ◽  
Tidal Currents ◽  
Tropical Storm ◽  
Surface Velocity ◽  
Surface Currents ◽  
West Florida Shelf ◽  
The West ◽  
Florida Shelf ◽  
East West

Abstract A dual-station high-frequency Wellen Radar (WERA), transmitting at 16.045 MHz, was deployed along the west Florida shelf in phased array mode during the summer of 2003. A 33-day, continuous time series of radial and vector surface current fields was acquired starting on 23 August ending 25 September 2003. Over a 30-min sample interval, WERA mapped coastal ocean currents over an ≈40 km × 80 km footprint with a 1.2-km horizontal resolution. A total of 1628 snapshots of the vector surface currents was acquired, with only 70 samples (4.3%) missing from the vector time series. Comparisons to subsurface measurements from two moored acoustic Doppler current profilers revealed RMS differences of 1 to 5 cm s−1 for both radial and Cartesian current components. Regression analyses indicated slopes close to unity with small biases between surface and subsurface measurements at 4-m depth in the east–west (u) and north–south (υ) components, respectively. Vector correlation coefficients were 0.9 with complex phases of −3° and 5° at EC4 (20-m isobath) and NA2 (25-m isobath) moorings, respectively. Complex surface circulation patterns were observed that included tidal and wind-driven currents over the west Florida shelf. Tidal current amplitudes were 4 to 5 cm s−1 for the diurnal and semidiurnal constituents. Vertical structure of these tidal currents indicated that the semidiurnal components were predominantly barotropic whereas diurnal tidal currents had more of a baroclinic component. Tidal currents were removed from the observed current time series and were compared to the 10-m adjusted winds at a surface mooring. Based on these time series comparisons, regression slopes were 0.02 to 0.03 in the east–west and north–south directions, respectively. During Tropical Storm Henri’s passage on 5 September 2003, cyclonically rotating surface winds forced surface velocities of more than 35 cm s−1 as Henri made landfall north of Tampa Bay, Florida. These results suggest that the WERA measured the surface velocity well under weak to tropical storm wind conditions.

The mineralogical composition of some Scottish soils

1925 ◽  
Vol 15 (3) ◽  
pp. 257-271 ◽  
Author(s):  
James Hendrick ◽  
George Newlands
Keyword(s):  
Mineralogical Composition ◽  
Fine Sand ◽  
Plant Food ◽  
Sand Fraction ◽  
Extensive Survey ◽  
North East ◽  
The North ◽  
Local Origin ◽  
East West ◽  
Made In

1. Previous investigations showed that certain Scottish soils were of glacial drift origin, that they were comparatively rich in unweathered silicates and therefore in reserves of plant-food, that they showed considerable variation in such silicates and were capable of classification accordingly. Some indication was also shown that the glacial drift, and hence the resulting soil, was sometimes of local origin, its character being determined by the underlying rock. In the present investigation a more extensive survey of Scottish soils has been made in order to discover to what extent these preliminary findings might be applicable generally.2. For this purpose soils have been collected from various localities in the north, north-east, west and south of Scotland, and have been analysed mechanically and the “fine sand” fraction examined mineralogically.

scholarly journals Monitoring and Analysis of Dynamic Characteristics of Super High-rise Buildings using GB-RAR: A Case Study of the WGC under Construction, China

2020 ◽  
Vol 10 (3) ◽  
pp. 808 ◽  
Author(s):  
Lv Zhou ◽  
Jiming Guo ◽  
Xuelin Wen ◽  
Jun Ma ◽  
Fei Yang ◽  
...  
Keyword(s):  
Wavelet Analysis ◽  
Dynamic Characteristics ◽  
Horizontal Displacement ◽  
Dynamic Monitoring ◽  
High Rise ◽  
The North ◽  
Study Results ◽  
Under Construction ◽  
East West

Accurate dynamic characteristics of super high-rise buildings serve as a guide in their construction and operation. Ground-based real aperture radar (GB-RAR) techniques have been applied in monitoring and analyzing the dynamic characteristics of different buildings, but only few studies have utilized them to derive the dynamic characteristics of super high-rise buildings, especially those higher than 400 m and under construction. In this study, we proposed a set of technical methods for monitoring and analyzing the dynamic characteristics of super high-rise buildings based on GB-RAR and wavelet analysis. A case study was conducted on the monitoring and analysis of the dynamic characteristics of the Wuhan Greenland Center (WGC) under construction (5–7 July 2017) with a 636 m design height. Displacement time series was accurately derived through GB-RAR and wavelet analysis, and the accuracy reached the submillimeter level. The maximum horizontal displacement amplitudes at the top of the building in the north–south and east–west directions were 18.84 and 15.94 mm, respectively. The roof displacement trajectory of the WGC was clearly identified. A certain negative correlation between the temperature and displacement changes at the roof of the building was identified. Study results demonstrate that the proposed method is effective for the dynamic monitoring and analysis of super high-rise buildings with noninvasive and nondestructive characteristics.

scholarly journals Modulation of Near-Inertial Oscillations by Low-Frequency Current Variations on the Inner Scotian Shelf

2019 ◽  
Vol 49 (2) ◽  
pp. 329-352 ◽  
Author(s):  
Pengcheng Wang ◽  
Zhongjie He ◽  
Keith R. Thompson ◽  
Jinyu Sheng
Keyword(s):  
High Frequency ◽  
Spatial Scales ◽  
Slab Model ◽  
Boundary Current ◽  
Scotian Shelf ◽  
Inertial Oscillations ◽  
Study Region ◽  
Shelf Circulation ◽  
High Frequency Radar ◽  
Adcp Observations

AbstractNear-inertial oscillations (NIOs) on the inner Scotian shelf are studied using observations, a simple slab model, and two operational shelf circulation models. High-frequency radar and ADCP observations from December 2015 to February 2016 show that individual NIO events forced by time-varying wind stress typically lasted for three to four inertial periods. NIOs with speeds exceeding 0.25 m s−1 were observed in the offshore part of the study region, but their amplitudes decreased shoreward within ~40 km of the coast. The NIOs had spatial scales of ~80 and ~40 km in the alongshore and cross-shore directions, respectively. The NIO phases varied moving from west to east, consistent with the typical movement of winter storms across the study region. Evolving rotary spectral analysis reveals that the peak frequency fp of the NIOs varied with time by ~7% of the local inertial frequency. The variation in fp can be explained in part by local wind forcing as demonstrated by the slab model. The remaining variation in fp can be explained in part by variations in the background vorticity associated with changes in the strength and position of the Nova Scotia Current, an unstable baroclinic boundary current that runs along the coast to the southwest. Two operational shelf circulation models are used to examine the abovementioned features in the high-frequency-radar and ADCP observations. The models reproduce the spatial structure of the NIOs and, in a qualitative sense, the temporal variations of fp.

signals, namely the measurement of the partial dis-charge pulse current. The Roche coil works in mag-netic coupling, and the detecting circuit and the high-voltage circuit has no direct contact, so it is very suitable for the partial discharge site inspection in the high-voltage switchgear. 3 APPLICATION OF HIGH-FREQUENCY PULSE CURRENT SENSOR IN THE WAIST STATION FOR 35 KV SWITCH CABINET A 220 KV waist station is located on a hill, which is far from about 2 km to the north of Yang street , 4 DATA DETECTION AND ANALYSIS OF Lufeng town, Lufeng country of Chuxiong city , alti-SWITCHGEAR HIGH FREQUENCY FOR tude 1923 km, which covers an area of 22876 m PARTIAL DISCHARGE and put into production on December 25, 2009. It is one of the most important substation of Chuxiong During the 2-month testing for the Chuxiong waist Lufeng area. The main power source is supplied by station , we selected the data from April 23 to May 220 KV and 500 KV peace waist I changed back 25 in 2014 for effective analysis, and found that the line, 220 kV and waist II loop power. current data of the eight high-frequency pulse cur-rent sensor is normal, so we selected three sensor

2015 ◽  
pp. 71-73
Keyword(s):  
High Voltage ◽  
High Frequency ◽  
Direct Contact ◽  
Pulse Current ◽  
Partial Discharge ◽  
Current Data ◽  
Data Detection ◽  
The North ◽  
Effective Analysis ◽  
Frequency Pulse

scholarly journals The Historical and Psychological Significance of the Unorganized Games of New Zealand Primary School Children

2021 ◽  
Author(s):  
◽  
Brian Sutton-Smith
Keyword(s):  
New Zealand ◽  
Primary School ◽  
Small Group ◽  
School Children ◽  
Primary School Children ◽  
The North ◽  
Psychological Significance ◽  
East And West ◽  
Recurrent Motifs ◽  
East West

<p>In the Spring of 1948 while teaching at a primary school, I observed a small group of girls playing a game called "Tip the Finger". During the game one of the players chanted the following rhyme: "Draw a snake upon your back And this is the way it went North, South, East, West, Who tipped your finger?" I recognized immediately and with some surprise that this rhyme contained elements which were not invented by the children and were probably of some antiquity. I knew, for example, though only in a vague and unlearned manner, that the four pattern of the North, South, East and West and the Snake symbolism were recurrent motifs in mythology and folklore. I was aware also that there did not exits any specialized attempt to explain the part that games of this nature played in the lives of the players.</p>

scholarly journals EVOLUTION OF KARAKORAM SEQUENCE, HUNZA VALLEY NE PAKISTAN: EVIDENCES FROM FIELD MAPPING AND MICRO-ANALYTICAL WORK

2020 ◽  
Vol 5 ◽  
pp. 19
Author(s):  
S. S. Baig ◽  
C. Xue ◽  
Masroor Alam ◽  
Naeem Ullah ◽  
M. Alam ◽  
...  
Keyword(s):  
Geological Mapping ◽  
Central Portion ◽  
High Grade ◽  
Metamorphic Complex ◽  
Field Mapping ◽  
The North ◽  
Analytical Work ◽  
History Of ◽  
Micro Analysis ◽  
East West

The Karakoram metamorphic Complex (KMC) in the southern Karakoram block is one of the best examples of Barrovian type metamorphism that comprises numerous exhumed metapelite units where a series of low to high grade (green schist to sillimanite facie) rocks are exposed. This sequence shows a complex polyphase history of metamorphism and deformation which offer deeper understanding of collision orogeny. Karakoram metamorphic Complex contains metapelites, meta-carbonates, meta-igneous and amphibolite layers, cross-cut by granite sheets in the northern part. This complex is bounded to the north by the Hunza plutonic unit which is the central portion of the massive east-west trending Karakoram axial batholith and to the southwest by the Main Karakoram thrust (MKT). In this contribution, we provide detail geological mapping, petrography, geochemistry and micro-analytical work using Electron Prob-micro analysis in the central Hunza Valley.

Sign in / Sign up

Export Citation Format

Share Document