scholarly journals Microstructure Measurements from an Underwater Glider in the Turbulent Faroe Bank Channel Overflow

2014 ◽  
Vol 31 (5) ◽  
pp. 1128-1150 ◽  
Author(s):  
Ilker Fer ◽  
Algot K. Peterson ◽  
Jenny E. Ullgren
Keyword(s):  
Dissipation Rate ◽  
Bottom Layer ◽  
Buoyancy Frequency ◽  
Underwater Glider ◽  
High Quality ◽  
Velocity Scale ◽  
Microstructure Measurements ◽  
Shear Probe ◽  
Better Than ◽  
Made In

AbstractMeasurements of ocean microstructure are made in the turbulent Faroe Bank Channel overflow using a turbulence instrument attached to an underwater glider. Dissipation rate of turbulent kinetic energy ε is measured using airfoil shear probes. A comparison is made between 152 profiles from dive and climb cycles of the glider during a 1-week mission in June 2012 and 90 profiles collected from the ship using a vertical microstructure profiler (VMP). Approximately one-half of the profiles are collocated. For 96% of the dataset, measurements are of high quality with no systematic differences between dives and climbs. The noise level is less than 5 × 10−11 W kg−1, comparable to the best microstructure profilers. The shear probe data are contaminated and unreliable at the turning depth of the glider and for U/ut < 20, where U is the flow past the sensor, ut = (ε/N)1/2 is an estimate of the turbulent velocity scale, and N is the buoyancy frequency. Averaged profiles of ε from the VMP and the glider agree to better than a factor of 2 in the turbulent bottom layer of the overflow plume, and beneath the stratified and sheared plume–ambient interface. The glider average values are approximately a factor of 3 and 9 times larger than the VMP values in the layers defined by the isotherms 3°–6° and 6°–9°C, respectively, corresponding to the upper part of the interface and above. The discrepancy is attributed to a different sampling scheme and the intermittency of turbulence. The glider offers a noise-free platform suitable for ocean microstructure measurements.

scholarly journals Microstructure measurements and estimates of entrainment in the Denmark Strait overflow plume

Ocean Science ◽  
2013 ◽  
Vol 9 (6) ◽  
pp. 1003-1014 ◽  
Author(s):  
V. Paka ◽  
V. Zhurbas ◽  
B. Rudels ◽  
D. Quadfasel ◽  
A. Korzh ◽  
...  
Keyword(s):  
Interfacial Layer ◽  
Dissipation Rate ◽  
Gravity Current ◽  
Depth Interval ◽  
Buoyancy Frequency ◽  
Entrainment Rate ◽  
Ambient Water ◽  
Denmark Strait ◽  
Microstructure Measurements ◽  
Free Falling

Abstract. To examine processes controlling the entrainment of ambient water into the Denmark Strait overflow (DSO) plume/gravity current, measurements of turbulent dissipation rate were carried out by a quasi-free-falling (tethered) microstructure profiler (MSP). The MSP was specifically designed to collect data on dissipation-scale turbulence and fine thermohaline stratification in an ocean layer located as deep as 3500 m. The task was to perform microstructure measurements in the DSO plume in the lower 300 m depth interval including the bottom mixed layer and the interfacial layer below the non-turbulent ambient water. The MSP was attached to a Rosette water sampler rack equipped with a SeaBird CTDO and an RD Instruments lowered acoustic Doppler current profiler (LADCP). At a chosen depth, the MSP was remotely released from the rack to perform measurements in a quasi-free-falling mode. Using the measured vertical profiles of dissipation, the entrainment rate as well as the bottom and interfacial stresses in the DSO plume were estimated at a location 200 km downstream of the sill at depths up to 1771 m. Dissipation-derived estimates of entrainment were found to be much smaller than bulk estimates of entrainment calculated from the downstream change of the mean properties in the plume, suggesting the lateral stirring due to mesoscale eddies rather than diapycnal mixing as the main contributor to entrainment. Dissipation-derived bottom stress estimates are argued to be roughly one third the magnitude of those derived from log velocity profiles. In the interfacial layer, the Ozmidov scale calculated from turbulence dissipation rate and buoyancy frequency was found to be linearly proportional to the overturning scale extracted from conventional CTD data (the Thorpe scale), with a proportionality constant of 0.76, and a correlation coefficient of 0.77.

scholarly journals Microstructure measurements and estimates of entrainment in the Denmark Strait overflow plume

2013 ◽  
Vol 10 (4) ◽  
pp. 1067-1098 ◽  
Author(s):  
V. Paka ◽  
V. Zhurbas ◽  
B. Rudels ◽  
D. Quadfasel ◽  
A. Korzh ◽  
...  
Keyword(s):  
Interfacial Layer ◽  
Dissipation Rate ◽  
Gravity Current ◽  
Depth Interval ◽  
Buoyancy Frequency ◽  
Entrainment Rate ◽  
Ambient Water ◽  
Denmark Strait ◽  
Microstructure Measurements ◽  
Free Falling

Abstract. To examine processes controlling the entrainment of ambient water into the Denmark Strait overflow (DSO) plume/gravity current, measurements of turbulent dissipation rate were carried out by a quasi-free-falling (tethered) microstructure profiler (MSP). The MSP was specifically designed to collect data on dissipation-scale turbulence and fine thermohaline stratification in an ocean layer to depths of 3500 m. The task was to perform microstructure measurements in the DSO plume in the lower 300 m depth interval including the bottom mixed layer and the interfacial layer below the non-turbulent ambient water. The MSP was attached to a Rosette water sampler rack equipped with a SeaBird CTDO and an RD Instruments Lowered Acoustic Doppler Current Profiler (LADCP). At a chosen depth, the MSP was remotely released from the rack to perform measurements in a quasi-free-falling mode. Using the measured vertical profiles of dissipation, the entrainment rate as well as the bottom and interfacial stresses were estimated in the DSO plume at a location 200 km downstream of the sill at depths up to 1771 m. Dissipation-derived estimates of entrainment were found to be much smaller than bulk estimates of entrainment calculated from the downstream change of the mean properties in the plume, suggesting the lateral stirring due to meso-scale eddies rather than diapycnal mixing as the main contributor to entrainment. Dissipation-derived bottom stress estimates are argued to be roughly one-third the magnitude of those from log velocity profiles. In the interfacial layer, the Ozmidov scale calculated from turbulence dissipation rate and buoyancy frequency was found to be linearly proportional to the overturning scale extracted from conventional CTD data (the Thorpe scale), with a proportionality constant of 0.76, and a correlation coefficient of 0.77.

scholarly journals Non-destructive handheld XRF study of archaeological composite silver objects—the case study of the late Roman Seuso Treasure

2021 ◽  
Vol 13 (5) ◽  
Author(s):  
Viktória Mozgai ◽  
Bernadett Bajnóczi ◽  
Zoltán May ◽  
Zsolt Mráv
Keyword(s):  
Fluorescence Analysis ◽  
The Body ◽  
High Quality ◽  
X Ray ◽  
Composite Objects ◽  
Mechanical Attachment ◽  
Non Destructive ◽  
Made In ◽  
Late Roman

AbstractThis study details the non-destructive chemical analysis of composite silver objects (ewers, situlas, amphora and casket) from one of the most significant late Roman finds, the Seuso Treasure. The Seuso Treasure consists of fourteen large silver vessels that were made in the fourth–early fifth centuries AD and used for dining during festive banquets and for washing and beautification. The measurements were systematically performed along a pre-designed grid at several points using handheld X-ray fluorescence analysis. The results demonstrate that all the objects were made from high-quality silver (above 90 wt% Ag), with the exception of the base of the Geometric Ewer B. Copper was added intentionally to improve the mechanical properties of soft silver. The gold and lead content of the objects shows constant values (less than 1 wt% Au and Pb). The chemical composition as well as the Bi/Pb ratio suggests that the parts of the composite objects were manufactured from different silver ingots. The ewers were constructed in two ways: (i) the base and the body were made separately, or (ii) the ewer was raised from a single silver sheet. The composite objects were assembled using three methods: (i) mechanical attachment; (ii) low-temperature, lead-tin soft solders; or (iii) high-temperature, copper-silver hard solders. Additionally, two types of gilding were revealed by the XRF analysis, one with remnants of mercury, i.e. fire-gilding, and another type without remnants of mercury, presumably diffusion bonding.

Study of Ancient Land Boundaries at Tauric Chersonesos Using Satellite Images

2019 ◽  
Vol 25 (1) ◽  
pp. 44-58 ◽  
Author(s):  
Edgar A. Terekhin ◽  
Tatiana N. Smekalova
Keyword(s):  
Remote Sensing ◽  
Information Systems ◽  
Geographic Information Systems ◽  
Satellite Images ◽  
Agricultural Land ◽  
Remote Sensing Data ◽  
Field Surveys ◽  
The 1960S ◽  
Better Than ◽  
Made In

Abstract The near chora (agricultural land) of Tauric Chersonesos was investigated using multiyear remote sensing data and field surveys. The boundaries of the land plots were studied with GIS (Geographic Information Systems) technology and an analysis of satellite images. Reliable reconstruction of the borders has been done for 231 plots (from a total of about 380), which is approximately 53% of the Chersonesean chora. During the last 50 years, most of the ancient land plots have been destroyed by modern buildings, roads, or forests. However, in the 1960s, a significant part of the chora was still preserved. Changes in preservation with time were studied with the aid of satellite images that were made in 1966 and 2015. During that period, it was found that the number of plots with almost-complete preservation decreased from 47 to 0. Those land plots whose preservation was better than 50% dropped from 104 to 4. A temporal map shows this decline in preservation. It was found that the areas of land plots could be determined accurately with satellite images; compared to field surveys, this accuracy was about 99%.

Introducing Problem-based Learning to Special Needs Dentistry—A Case Study

2002 ◽  
Vol os9 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Raman Bedi ◽  
Jackie A Champion ◽  
Roger Davies
Keyword(s):  
Special Needs ◽  
Problem Based Learning ◽  
Chi Square ◽  
Training And Education ◽  
Mixed Response ◽  
Conventional Teaching ◽  
The Subject ◽  
Better Than ◽  
Made In

Introduction In order to promote training and education in special-needs dentistry an attempt was made to introduce problem-based learning (PBL) as a method of postgraduate dental education. The aim of this paper was to review the principles of PBL and report on a case study using this methodology. Method The case study was of a PBL session, on the subject of ‘problems of obtaining appropriate dental care for people with epilepsy’, undertaken at a national conference. Delegates were asked to complete a pre- and post-session questionnaire on PBL and their attitudes to the session. Results The session received a mixed response. Only 33 (35%) thought the session was valuable and only 20 (31%) thought it was better than conventional teaching methods and yet over half (55%) said they would like to attend more PBL in special-needs dentistry. Professionals complementary to dentistry were more likely to find the PBL session of value and to prefer the method to a more conventional format than dentists were (chi-square=5.5, df=1, p<0.05 and chi-square=5.9, df=1, p<0.05 respectively). Conclusion Valuable feedback was received from delegates. This will enable improvements to be made in future courses so that the effectiveness of PBL can be optimised.

FURTHER STUDIES ON NATURAL SELECTION AMONG HYBRIDS OF CARDUUS ACANTHOIDES AND CARDUUS NUTANS

1964 ◽  
Vol 42 (12) ◽  
pp. 1605-1613 ◽  
Author(s):  
R. J. Moore ◽  
G. A. Mulligan
Keyword(s):  
Natural Selection ◽  
Chromosome Number ◽  
Parental Species ◽  
Experimental Studies ◽  
Great Decrease ◽  
Carduus Acanthoides ◽  
Carduus Nutans ◽  
Experimental Plots ◽  
Better Than ◽  
Made In

A third 5-year survey made in 1962 of Carduus acanthoides, C. nutans, and their hybrids in Grey Co., Ontario, revealed that a great decrease in these populations had occurred. C. acanthoides and hybrids similar to this species had survived better than C. nutans but very little spread of either species seemed to have occurred in 1957–1962. In experimental plots the hybrid has been made and backcrossed to the parental species. The species differ in chromosome number (C. acanthoides, 2n = 22; C. nutans, 2n = 16) and hybrids have intermediate numbers. Evidence was found from field and experimental studies that the progeny of the F1 hybrid included a greater proportion of seedlings with the higher chromosome numbers than with the lower and intermediate numbers. It is suggested that this selection may operate through the rejection of the longer chromosomes received from C. nutans, which, in certain zygotic combinations may constitute an excess of chromatin lethal to the zygote.

Snap! Recognising Implicit Actions in Static Point-Light Displays

Perception ◽  
10.1068/p6320 ◽  
2009 ◽  
Vol 38 (4) ◽  
pp. 613-616 ◽  
Author(s):  
Russell Reid ◽  
Anna Brooks ◽  
Duncan Blair ◽  
Rick van der Zwan
Keyword(s):  
Biological Motion ◽  
Neural Mechanisms ◽  
Point Light ◽  
Static Point ◽  
Better Than ◽  
Made In

Johansson (1973 Perception & Psychophysics14 201–211) suggested that point-light displays that are static—so-called ‘snapshots’—contain little or no information about the actor or their action. Here we present data that suggest even naive observers can perceive such information from static point-light arrays. Observers were able, at rates better than chance, to discriminate the directions of facing of sagittally viewed static point-light walkers. The data show also that, without feedback, performances improved with experience. Our data have implications for assumptions made in designing experiments with point-light displays and for models of the neural mechanisms mediating biological motion perceptions.

scholarly journals Response of Recycled Brick Aggregate Concrete to High Temperatures

2019 ◽  
Vol 8 (10) ◽  
pp. 224-227
Keyword(s):  
Mechanical Properties ◽  
Air Pollution ◽  
Compressive Strength ◽  
Construction Industry ◽  
Fire Performance ◽  
Demolition Waste ◽  
Aggregate Concrete ◽  
Different Temperatures ◽  
Better Than ◽  
Made In

The abundant availability of demolition waste from construction industry is leading towards a significant problem of disposal, land and air pollution. The natural aggregate resources are also depleting due to development of construction activities. An attempt is made in this study to convert this waste into wealth by substituting the recycled brick from demolition waste to granite aggregate in production of the concrete. The granite aggregate (GA) is replaced with recycled brick aggregate (RBA) by 25% of its weight to produce M15 and M20 grades of concrete. The granite aggregate concrete (GAC) and recycled brick aggregate concrete (RBAC) were subjected to different temperatures between 100 to 1000oC for a duration of 3 hours and the mechanical properties such as compressive strength and flexural strength were examined to assess its fire performance. The response of RBAC is better than GAC at each temperature. The study revealed that the residual strength increases with the increase in grade of concrete at all temperatures.

scholarly journals ANALISA UNJUK KERJA MESIN STEMPEL FLASH MADE IN TIONGKOK MEREK FLAZ TERHADAP MESIN STEMPEL FLASH MADE IN INDONESIA MEREK MD

2020 ◽  
Vol 2 (1) ◽  
pp. 13-18
Author(s):  
Slamet Raharjo ◽  
Massus Subekti ◽  
Imam Arif Raharjo
Keyword(s):  
Grounded Theory ◽  
Electricity Consumption ◽  
Operation Time ◽  
Electrical Energy ◽  
Quality Parameter ◽  
Theory Approach ◽  
Machine Performance ◽  
Work Method ◽  
Better Than ◽  
Made In

This research aimed to find out the work method of flash stamp machine made in Tiongkok brand Flaz and flash stamp machine made in Indonesia brand MD observed from each machine performance including colour stamp quality resulted, duration in its operation, as well as power and electricity consumption. The research method adopted is qualitative method with grounded theory approach. This research conducted in Enterprise of Flash Stamp Machine made in Indonesia brand MD on Jl. Lembang Baru I West Sudimara, Ciledug, Tangerang, Banten. The result drawn from work method research of both flash stamp machine are: First,   the stamp quality resulted by flash stamp machine brand MD was better than flash stamp machine brand MD. Second, the operation time of flash stamp machine brand MD was 4 second faster, that is 3 second, while flash sta mp machine brand Flaz was 4 second. Third, the electricity power consumption of flash stamp machine brand Flaz was smaller that is 136,62 watt, while brand Flaz was 392,34 watt. Fourth, the electrical energy consumption of flash stamp machine Flaz was smaller that is 888,39 Joule, while flash stamp machine brand MD was 1709,06. The conclusion drawn from work method research of flash stamp machine made in Tiongkok brand Flaz toward flash stamp machine made in Indonesia brand MD measured from stamp output quality parameter and operation time speed, so flash stamp machine made in Indonesia brand MD is better than flash stamp machine made in Tiongkok brand Flaz. Abstrak Penelitian ini bertujuan untuk mengetahui unjuk kerja mesin stempel flash made in Tiongkok merek Flaz terhadap mesin stempel flash made in Indonesia merek MD dilihat dari performa masing-masing mesin meliputi kualitas cap stempel warna yang dihasilkannya, lama waktu pengoperasiannya, pemakaian daya serta konsumsi energi listriknya. Metode penelitian yang di gunakan adalah metode kualitatif dengan pendekatan penelitian grounded theory. Penelitian ini dilakukan di Perusahaan Pembuatan Mesin Stempel Flash made In Indonesia merek MD di Jl. Lembang Baru I Kelurahan Sudimara Barat, Ciledug, Tangerang, Banten. Hasil yang diperoleh dari penelitian unjuk kerja kedua mesin stempel flash ini adalah :  Pertama, kualitas cap stempel yang dihasilkan mesin stempel flash merek MD lebih bagus dibandingkan mesin stempel flash merek Flaz. Kedua, lama waktu operasinya 4 detik lebih cepat mesin stempel flash merek MD yaitu selama 3 detik dan 4 detik untuk mesin stempel flash merek Flaz. Ketiga, daya listrik yang dibutuhkan lebih kecil me sin stempel flash merek Flaz yaitu sebesar 136,62 watt dan 392,34 Watt untuk merek Flaz. Keempat, konsumsi energi listrik yang dibutuhkan lebih kecil mesin stempel merek Flaz yaitu 888,39 Joule dan 1709,06 Joule untuk mesin stempel flash merek MD. Kesimpulan yang diperoleh dari penelitian unjuk kerja mesin stempel flash made in Tiongkok merek Flaz terhadap mesin stempel flash made in Indonesia merek MD diukur dari parameter kualitas hasil cap dan kecepatan waktu operasi maka mesin stempel flash made in Indonesia merek MD lebih bagus dari pada mesin stempel flash made in Tiongkok merek Flaz.

De politieke participatie aan de gemeenteraadsverkiezingen

Res Publica ◽  
1970 ◽  
Vol 12 (3) ◽  
pp. 311-338
Author(s):  
Wilfried Dewachter ◽  
Edith Lismont
Keyword(s):  
Legislative Elections ◽  
Municipal Politics ◽  
Municipal Policy ◽  
Municipal Elections ◽  
Frequent Use ◽  
The Government ◽  
Participation Research ◽  
National Electorate ◽  
Better Than ◽  
Made In

Municipal elections are not the only channel of participation in the municipal policy nor are they the only participation-problem. But it is nevertheless useful to make research into them because they are the unique institutionalized possibility of participation.This participation-research deals with the different aspects of the municipal elections.The first thing to note is that a number of council-members are pointed out by elections without competition. This phenomenon is not very extended: 373 out of some 2,600 municipalities, 12 % of the council members, 200,000 voters. There is no notable change of size since 1920 in this phenomenon.Compared to the legislative elections, candidatures are very stable and limited : an average of 2,3 candidates per seat. These limited candidatures also mean that in practically half of the cases municipal elections have a two-parties system, by which the electoral corps chose directly the Court of Mayor and Aldermen. But even in municipalities with more than two parties, this «direct choice of the government» is made in 75 % of the cases. In respect of these facts, participation is qualitatively much better than in the case of the parliamentary elections.Forsaking of choice is notably lower at municipal than at parliamentary elections. As to the use of preference-votes, the choice of the municipal electorate is richer than that of the national electorate not only because municipal electors more aften express their preference for individuals, but also and not in the least because, by this more frequent use of preference-votes, they have real participation in the choice of the councilmembers themselves.The possibilities of choice at municipal elections offer an original alternative : to vote beyond party-frontiers with the «mixed vote».  This multi-party vote is but seldom used : by 2,5 % of the electorate.And even then those who tlus mixed way lose half of their votingcapacity.  Generally seen however, the municipal elections show a more favorable participation-pattern than the legislative ones. This leads to the question if it can be imputed to the voters when something is wrong with municipal politics. Is this problem not-situated on a higher level of the participation-pyramid ?

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