Short Review of True-North Alignment Method on the Field Demonstrating the benefits of the use of an Optical Gyrocompass

2021 ◽  
Author(s):  
Frédéric Guattari ◽  
Pierrick Auregan ◽  
Elliot de Toldi ◽  
Theo Laudat ◽  
Laurent Mattio
Keyword(s):  
Seismic Station ◽  
Good Practice ◽  
Short Review ◽  
Orientation Error ◽  
The Past ◽  
The North ◽  
Single Station ◽  
Exhaustive Study ◽  
Added Uncertainty ◽  
Magnetic North

<p><span><span>To install a seismometer with a properly defined orientation - inside a vault or into a borehole - as a single station including various instruments or as a part of an array - an ‘adequate’ tool and an ‘absolute’ reference are needed.</span></span></p><p><span><span>In the past, and sometimes it persists nowadays, magnetic North have been used as a reference for Z-orientation of seismic station. Several studies have extensively measured the orientation error that have been made with this method, using an optical gyrocompass providing True-North as a reference, and their work will be summarized here.</span></span></p><p><span><span>In these studies, optical Gyrocompass is said to be the good solution, even if it is too heavy, expensive, and difficult to export. This paper will explain how iXblue has overcome these limitations to design the new-born Seistans Optical Gyrocompass.</span></span></p><p><span><span>Moreover, to aim True-North with a reliable accuracy is not the only think you need to do on the field. The method to transfer the North-line from the gyrocompass to the instrument to aligned must not induce errors that ruined the accuracy obtained using state-of-the-art gyrocompass. So an exhaustive study of the different ways to transfer the orientation from the compass to the aligned sensor will be presented, and corresponding added uncertainty will be evaluated, which is a good way to promote good practice on the field.</span></span></p><p><span><span>Finally, some figures will be gathered and shared from literature to quantify the precision needed for the alignment of a seismic sensor. There are today so few papers about this important matter that it is worth to spread their information.</span></span></p>

scholarly journals Rayleigh wave ellipticity measurements in the North Tanzanian Divergence (Eastern African Rift)

2020 ◽  
Author(s):  
Laura Parisi ◽  
Andrea Berbellini ◽  
P. Martin Mai
Keyword(s):  
Rayleigh Wave ◽  
Seismic Station ◽  
Seismic Network ◽  
Body Waves ◽  
Earth Structure ◽  
Velocity Models ◽  
The North ◽  
The Earth ◽  
Single Station ◽  
African Rift

<p>Rayleigh wave ellipticity depends, in theory, only on the Earth structure below a seismic station, offering the advantage of a “single-station” method to infer crustal properties. Therefore, ellipticity measurements can be used to construct pseudo 3-D shear velocity models of the earth structure using even seismic stations that did not record simultaneously.  </p><p>Based on that, we carried-out ellipticity measurements by using teleseismic waveforms recorded by the OPS seismic network we deployed at the western flank of the North Tanzanian Divergence between June 2016 and May 2018, covering 17 sites. We then expanded our measurements on the waveforms recorded by the adjacent CRAFTI seismic network from January 2013 and December 2014, available on IRIS, which comprised more than 30 sites. </p><p>While the OPS network covers the transition between the Tanzania Craton and North Tanzanian Divergence, the CRAFTI network is entirely contained in the North Tanzanian Divergence. Therefore, the imaging that can be obtained by integrating the two asynchronous passive seismology experiments will help to better understand the dynamics of this segment of the eastern branch of the Eastern African Rift.</p><p>Preliminary results show heterogeneity structure that are in agreement with previous tomographic studies based on ambient noise cross-correlation and body-waves arrival-times. In regions where previous seismological studies are not available, results match the known geological structure of the transition between the Tanzanian Craton and the North Tanzanian Divergence. This demonstrates that measurements of ellipticity can be a useful and integrative tool for earth structure imaging, especially at the edges of the active rifts where the seismicity is scarce.</p><p><br><br><br></p>

scholarly journals A SHORT REVIEW OF THE NORTH AMERICAN SPECIES OE PSEUDISTER (COLEOPTERA, HISTERIDAE)

1935 ◽  
Vol 67 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Howard E. Hinton
Keyword(s):  
New York ◽  
North American ◽  
British Museum ◽  
Short Review ◽  
North American Species ◽  
The Past ◽  
The North

While determining a collection of interesting Histeridae taken by the writer and others in Mexico during the past few years, three species were found to belong to the genus Pseudister Bickhardt. As two of these were undescribed, and as one species described from New York and one from Paraguay have been masquerading for many years under a different genus, the following short review is necessary to straighten out the existing confusion. Through the kindness of Dr. K. G. Blair and Dr H. Scott of the British Museum, types of all the species considered in this paper have been examined by the writer.

Interrogating the Constitutionality of Federal Character Principle in Nigeria

2018 ◽  
Vol 9 (07) ◽  
pp. 20492-20498
Author(s):  
Aborisade Olasunkanmi ◽  
Christopher Agulanna
Keyword(s):  
Ethnic Groups ◽  
Research Work ◽  
National Unity ◽  
The Past ◽  
The North ◽  
Inhibiting Factors

This work interrogates federal character principle (FCP) in Nigeria. The FCP was designed to fundamentally address the striking features of Nigeria politics of intense struggles for power among the different ethnic groups in the country between the elites from the North and their Southern counterparts and the various segments, but the practice of FCP in Nigeria so far raises curiosity and doubts. Given the outcome of the interrogation, this research work discovered and conclude that federal character has not indeed achieve its objective in the Nigeria, the study finds that Ethnocentrism, Elitism, Mediocrity, Mutual suspicion amongst others accounts for some inhibiting factors of the FCP in Nigeria. Like many other provisions of the Constitution, the Federal Character principle was meant to correct some imbalances experienced in the past, but it has created more problems than it has attempted to solve. Rather than promote national unity, it has disunited Nigerians. There is an urgent need to use more of professionals and result oriented Nigerians to carry out national tasks, than to use unprogressive people due to this "Federal character" issue. Nigeria should be a place where one's track records and qualifications are far greater than just "where they come from" or their lineage if Nigerian truly want to progress.

Colchicum autumnale (Colchicaceae) w okolicach Krakowa – dawne i obecne rozmieszczenie

2019 ◽  
pp. 15-27
Author(s):  
Magdalena Zarzyka-Ryszka
Keyword(s):  
Adjacent Area ◽  
Colchicum Autumnale ◽  
The Past ◽  
The North ◽  
North Eastern ◽  
New Localities ◽  
Present Distribution ◽  
The 19Th Century ◽  
North Eastern Part

The paper describes the past and present distribution of Colchicum autumnale in the vicinity of Cracow, highlights the role of Stanisław Dembosz (who published the first locality of C. autumnale near Igołomia in 1841). Gives information about the occurrence of C. autumnale in Krzeszowice in the 19th century (reported by Bronisław Gustawicz), presents new localities noted in 2012–2014 in meadows in the north-eastern part of the Puszcza Niepołomicka forest and adjacent area (between the Vistula and Raba rivers), and gives a locality found in Cracow in 2005 (no longer extant).

Present Status of the Salmonids Atlantic Salmon and Sea-Trout in the Dutch Part of the River Rhine

1994 ◽  
Vol 29 (3) ◽  
pp. 37-41 ◽  
Author(s):  
W. G. Cazemier
Keyword(s):  
Atlantic Salmon ◽  
Salmo Trutta ◽  
Natural Populations ◽  
River Rhine ◽  
Sea Trout ◽  
The Past ◽  
The North ◽  
Trout Population ◽  
The North Sea ◽  
Heavy Pollution

In the past, the anadromous salmonids, Atlantic salmon (Salmo salar) and sea-trout (Salmo trutta), have formed natural populations in the river Rhine. From the beginning of the nineteenth century onwards, the greater part of the drainage area of the river has been gradually altered from a more or less rural and agricultural area, into a highly industrialised one with subsequent industrialisation, river-engineering and heavy pollution. These developments are considered to be the major cause for the disappearance of the populations of anadromous salmonid fish in the 1950s. The water quality has recovered significantly during the past 25 years. From about 1975 onwards, this process gave rise to a recovery of the anadromous trout population. Results of recent studies of the sea-trout migration pattern are presented. They reveal that nowadays these salmonids can complete their up- and downstream migrations from the North Sea to places, situated at hundreds of kilometres upward the river and vica versa. The numbers of recorded Atlantic salmon and catch locations in inland waters are presented. They show a significant increase since 1989. These phenomena can be understood as promising signs of the recovery of the Rhine aquatic ecosystem.

Uncommon Grounds

2017 ◽  
Author(s):  
Jeffrey Lawrence
Keyword(s):  
American Literature ◽  
Latin American ◽  
Historical Novel ◽  
Latin American Literature ◽  
Historical Account ◽  
American Novel ◽  
Song Of Solomon ◽  
The Past ◽  
The North ◽  
The Us

This chapter turns from a historical account of the development of the US literature of experience and the Latin American literature of reading to a textual analysis of the US and Latin American historical novel. Hemispheric/inter-American scholars often cite William Faulkner’s Absalom, Absalom! (1936), Gabriel García Márquez’s One Hundred Years of Solitude (1967), and Toni Morrison’s Song of Solomon (1977) as exemplifying instances of literary borrowing across the North–South divide. As I demonstrate, however, each of the later texts also realigns its predecessor’s historical imaginary according to the dominant logics of the US and Latin American literary fields. Whereas the American works foreground experiential models of reconstructing the past and conveying knowledge across generations, García Márquez’s Latin American novel presents reading as the fundamental mode of comprehending and transmitting history.

scholarly journals Response Characteristics of Chinese Pine (Pinus tabulaeformis Carr.) Radial Growth to Climate and Drought Variability Reconstruction in Western Liaoning, Northeast China

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 752
Author(s):  
Liu ◽  
Bao ◽  
Bao
Keyword(s):  
Northeast China ◽  
Radial Growth ◽  
Pinus Tabulaeformis ◽  
Western Liaoning ◽  
Chinese Pine ◽  
The Past ◽  
The North ◽  
Pinus Tabulaeformis Carr ◽  
The North Pacific

Chinese pine (Pinus tabulaeformis Carr.) plays an important role in maintaining ecosystem health and stability in western Liaoning Province and the southern Horqin sand land, Northeast China, with benefits including sand fixation and soil erosion. In the context of climate change, developing a better understanding of the relationship between climate factors and growth rates of this species will be extremely valuable in guiding management activities and meeting regional conservation objectives. Here, the results based on two groups of tree-ring samples show that the radial growth of Chinese pine is controlled primarily by water conditions. The longer chronology had the highest correlation coefficient with the January–September mean self-calibrating Palmer Drought Severity Index (scPDSI); therefore, drought variability was reconstructed for the period 1859–2014. Statistical analysis showed that our model explained 41.9% of the variance in radial growth during the 1951–2014 calibration period. Extreme dry and wet events, defined as the criteria of one standard deviation less or greater than the mean value, accounted for 19.9% and 18.6% of the 156-year climate record, respectively. During the past century, the regional hydroclimate experienced significant long-term fluctuations. The dry periods occurred from the early-1900s–1930s and 1980s–2000s, and the wet periods occurred from the 1940s–1970s. The drought reconstruction was consistent with the decreasing trend of the East Asian summer monsoon since the late 1970s. The reconstructed temporal patterns in hydroclimate in western Liaoning were closely related to the large-scale climate drivers in the North Pacific and the tropical equatorial Pacific. The teleconnections were confirmed by spatial correlations between the reconstructed sequence and sea surface temperature (SST) in the North Pacific, as well as the correlations with the Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) indices. Aerosols played an important role in affecting drought variations over the past several decades. Moisture stress caused by global warming and interdecadal changes in the PDO will have long-term effects on the growth of pines in the study area in the future.

scholarly journals Ensemble models on palaeoclimate to predict India's groundwater challenge

2013 ◽  
Vol 2 (3) ◽  
Author(s):  
Partha Sarathi Datta
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Humid Climate ◽  
Ensemble Models ◽  
North West ◽  
The Past ◽  
The North ◽  
14C Age

In many parts of the world, freshwater crisis is largely due to increasing water consumption and pollution by rapidly growing population and aspirations for economic development, but, ascribed usually to the climate. However, limited understanding and knowledge gaps in the factors controlling climate and uncertainties in the climate models are unable to assess the probable impacts on water availability in tropical regions. In this context, review of ensemble models on δ18O and δD in rainfall and groundwater, 3H- and 14C- ages of groundwater and 14C- age of lakes sediments helped to reconstruct palaeoclimate and long-term recharge in the North-west India; and predict future groundwater challenge. The annual mean temperature trend indicates both warming/cooling in different parts of India in the past and during 1901–2010. Neither the GCMs (Global Climate Models) nor the observational record indicates any significant change/increase in temperature and rainfall over the last century, and climate change during the last 1200 yrs BP. In much of the North-West region, deep groundwater renewal occurred from past humid climate, and shallow groundwater renewal from limited modern recharge over the past decades. To make water management to be more responsive to climate change, the gaps in the science of climate change need to be bridged.

ON "PLASTIC" WAVES IN SOLIDS

1959 ◽  
Vol 37 (9) ◽  
pp. 1017-1035 ◽  
Author(s):  
John M. Bowsher
Keyword(s):  
Theoretical Study ◽  
Short Review ◽  
Future Research ◽  
Past Work ◽  
The Past ◽  
Engineering Significance ◽  
The Subject

The study of the propagation of "plastic" waves in solids has reached a stage where it is necessary to consider which direction future research should take. In the past 90 or so years many experiments, mostly designed to elucidate certain points of engineering significance, and a few attempts at a theoretical study have cast some light on the subject and revealed it as one of formidable difficulty.Nearly all the experiments have of necessity relied on rather dubious theories for their interpretation, and part of the present paper will be devoted to a description of an apparatus which gives results capable of being interpreted with a very minimum of theory. The remainder of the paper is devoted to a short review of past work with particular emphasis on basic phenomena and to a brief discussion on the most pressing problems still remaining. The experiments described in the present paper bring to light a factor in the propagation of "plastic" waves that seems to have been overlooked in previous work.

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