On the Early Cambrian age of two late orogenic granites from. west-central Ahaggar (Algerian Sahara)

1969 ◽  
Vol 6 (1) ◽  
pp. 25-37 ◽  
Author(s):  
J. Boissonnas ◽  
S. Borsi ◽  
G. Ferrara ◽  
J. Fabre ◽  
J. Fabries ◽  
...  
Keyword(s):  
Random Sampling ◽  
Field Data ◽  
Large Scale ◽  
Early Cambrian ◽  
Basement Complex ◽  
West Central ◽  
Algerian Sahara ◽  
Igneous Activity ◽  
Made In

The Pharusian belt of west-central Ahaggar belongs to the 'basement complex' underlying the Paleozoic and later sediments of the Sahara. This paper reports and discusses the Rb–Sr ages obtained on total rocks and minerals from two granitic stocks of the belt: the Tioueiine and Iskel intrusions.Both plutons gave good whole-rock isochrons, which show that the systems were closed 560 ± 40 m.y. ago with respect to Rb and Sr. This is, most probably, the age of crystallization. Three of the four values obtained on biotites are somewhat lower and scattered in the range 502–526 m.y. The discrepancies are probably due to deuteric reactions or incipient weathering. They can be ascribed neither to the loss of 87Sr during the cooling down of the granites, nor to rejuvenation by some later thermal or tectonic event.These studies confirm previous results of random sampling in Ahaggar and prove that large-scale igneous activity took place during the Early Cambrian Epoch. Knowing from field data that the Tioueiine and Iskel are late orogenic granites, it must be concluded that the Pharusian orogeny came to an end at that time.Such a result contradicts early assumptions, made in the field, of a middle Precambrian age for the Pharusian orogeny. It gives further weight to modern ideas concerning the 700–500 m.y. events in Africa, and it leaves time for erosion to create the Saharian platform before the deposition of the first Paleozoic sandstones.

scholarly journals Indicator for peat natural recovery in Sebangau National Park in Central Kalimantan, Indonesia

2021 ◽  
Vol 914 (1) ◽  
pp. 012034
Author(s):  
T Setyawati ◽  
N Julianti ◽  
Pratiwi ◽  
B Mulyanto ◽  
A Subiakto
Keyword(s):  
Forest Fires ◽  
Vegetation Structure ◽  
Random Sampling ◽  
National Park ◽  
Field Data ◽  
Initial Condition ◽  
Central Kalimantan ◽  
Burned Areas ◽  
Drainage Canals ◽  
Made In

Abstract Most of the existing peatland area in Indonesia is degraded mainly due to human activities. This, in association with the construction of drainage canals, resulted in a lower water table compared to its natural condition, causing many changes. Although the criteria for damage and recovery have already been articulated into several existing regulations, yet the indicators for recovery have not been widely studied. For effective restoration, managers need to have basic data related to the initial condition of damaged areas or at least have data on areas that are able to recover naturally without human assistance. Random sampling was used to collect field data on vegetation structure and composition, including direct interviews with the resource persons. Observations made in several locations within the Sebangau National Park indicated that some areas are recovering naturally and relatively fast, although some are not. During 2017 forest fires, only 98.03 ha or burned areas were recorded. This can be seen from the species composition and the vegetation structure covering the studied area. Conditions in the field indicate that all peat forests have been fragmented through the existence of canals which are used for various activities.

scholarly journals Synthesis of Metal Organic Frameworks by Ball-Milling

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Cheng-An Tao ◽  
Jian-Fang Wang
Keyword(s):  
Ball Milling ◽  
Large Scale ◽  
Raw Materials ◽  
Metal Organic Frameworks ◽  
Research Topic ◽  
Mass Ratio ◽  
Time Consumption ◽  
Metal Organic ◽  
Short Time ◽  
Made In

Metal-organic frameworks (MOFs) have been used in adsorption, separation, catalysis, sensing, photo/electro/magnetics, and biomedical fields because of their unique periodic pore structure and excellent properties and have become a hot research topic in recent years. Ball milling is a method of small pollution, short time-consumption, and large-scale synthesis of MOFs. In recent years, many important advances have been made. In this paper, the influencing factors of MOFs synthesized by grinding were reviewed systematically from four aspects: auxiliary additives, metal sources, organic linkers, and reaction specific conditions (such as frequency, reaction time, and mass ratio of ball and raw materials). The prospect for the future development of the synthesis of MOFs by grinding was proposed.

scholarly journals Learning As It Happens: A Decade of Analyzing and Shaping a Large-Scale Online Learning System

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Matthieu J. S. Brinkhuis ◽  
Alexander O. Savi ◽  
Abe D. Hofman ◽  
Frederik Coomans ◽  
Han L. J. Van der Maas ◽  
...  
Keyword(s):  
Online Learning ◽  
Large Scale ◽  
Response Times ◽  
Learning System ◽  
Learning Gains ◽  
Online Experimentation ◽  
Quality Of Fit ◽  
Item Reliability ◽  
Made In

With the advent of computers in education, and the ample availability of online learning and practice environments, enormous amounts of data on learning become available. The purpose of this paper is to present a decade of experience with analyzing and improving an online practice environment for math, which has thus far recorded over a billion responses. We present the methods we use to both steer and analyze this system in real-time, using scoring rules on accuracy and response times, a tailored rating system to provide both learners and items with current ability and difficulty ratings, and an adaptive engine that matches learners to items. Moreover, we explore the quality of fit by means of prediction accuracy and parallel item reliability. Limitations and pitfalls are discussed by diagnosing sources of misfit, like violations of unidimensionality and unforeseen dynamics. Finally, directions for development are discussed, including embedded learning analytics and a focus on online experimentation to evaluate both the system itself and the users’ learning gains. Though many challenges remain open, we believe that large steps have been made in providing methods to efficiently manage and research educational big data from a massive online learning system.

The Big Push Déjà Vu: A Review of Jeffrey Sachs's The End of Poverty: Economic Possibilities for Our Time

2006 ◽  
Vol 44 (1) ◽  
pp. 96-105 ◽  
Author(s):  
William Easterly
Keyword(s):  
New York ◽  
Development Economics ◽  
Large Scale ◽  
The Poor ◽  
World Poverty ◽  
Incentive Problems ◽  
The 1950S ◽  
Déjà Vu ◽  
Big Push ◽  
Made In

Jeffrey Sachs's new book (The End of Poverty: Economic Possibilities for Our Time, Penguin Press: New York, 2005) advocates a “Big Push” featuring large increases in aid to finance a package of complementary investments in order to end world poverty. These recommendations are remarkably similar to those first made in the 1950s and 1960s in development economics. Today, as then, the Big Push recommendation overlooks the unsolvable information and incentive problems facing any large-scale planning exercise. A more promising approach would be to design incentives for aid agents to implement interventions piecemeal whenever they deliver large benefits for the poor relative to costs.

Parameterization of Directional Spectra and Its Influence on Ship Motion Predictions

1993 ◽  
Vol 37 (02) ◽  
pp. 138-147
Author(s):  
Ross Graham ◽  
Barbara-Ann Juszko
Keyword(s):  
Spectral Data ◽  
Field Data ◽  
Ship Motion ◽  
Flight Operations ◽  
Modeling Accuracy ◽  
Directional Wave ◽  
Made In

An approach to parameterizing directional spectra proposed by Hogben & Cobb based on a combination of the Ochi & Hubble 6-parameter spectrum and the Longuet-Higgins et al cos2p model is adopted for a study of directional parameterizations and their influence on ship motion predictions. Two schemes for evaluating the directional spreading parameters are assessed in terms of their ability to reproduce highly resolved measured directional spectra, and the best approach, termed the 10-parameter spectrum, is adopted. The applicability of the 10-parameter spectrum to hindcast spectra is investigated, and acceptable fits obtained for 93% of the spectra considered. An evaluation of the ability of the hindcast model to reproduce the measured spectral data is also made. In general, it is found that the differences between the hindcast spectra and associated 10-parameter fits are significantly smaller than the differences between the hindcast spectra and the field data, and it is concluded that the 10-parameter spectrum is a suitable basis for developing statistical descriptions of directional wave climates. The effects of directional parameterization on ship motion predictions are investigated by computing the ship responses as a function of heading for sample hindcast spectra, and the associated 10-parameter and Bretschneider 2-parameter spectra. The responses calculated using the 10-parameter spectrum are found to be in better agreement with the hindcast results than those obtained with the Bretschneider 2-parameter spectrum, with a significant improvement in modeling accuracy in the case of bi-modal spectra. The potential advantages of incorporating the 10-parameter spectrum in future operability analyses of flight operations is examined by comparing the head-to-wind roll response computed using hindcast spectra with that predicted using 10-parameter and Bretschneider spectra.

Oosterweel – from an underground and even underwater road infrastructure plan to an urban transformation project

2021 ◽  
Author(s):  
Luc Hellemans
Keyword(s):  
Traffic Flow ◽  
Large Scale ◽  
Good Reason ◽  
Urban Transformation ◽  
Construction Site ◽  
Successful Completion ◽  
Road Infrastructure ◽  
Living Space ◽  
The City ◽  
Made In

<p>For the coming ten years, the heart of Europe will turn into a gigantic construction site for works on one of the largest hubs of the continent: Antwerp. The Oosterweel Link is the project whereby the motorway ring around Antwerp is undergoing a metamorphosis to reinvigorate traffic flow and add living space to the City. The project had come to a standstill for several years as a result of protests by assertive citizens, but was given a second lease of life following a large-scale participation project.</p><p>To ensure its successful completion, unparalleled efforts are being made in the field and in the area of digitization. It is therefore with good reason that in Belgium the project is referred to as “the construction site of the century”.</p>

scholarly journals Mortars with CDW Recycled Aggregates Submitted to High Levels of CO2

2021 ◽  
Vol 6 (11) ◽  
pp. 159
Author(s):  
Ricardo Infante Gomes ◽  
David Bastos ◽  
Catarina Brazão Farinha ◽  
Cinthia Maia Pederneiras ◽  
Rosário Veiga ◽  
...  
Keyword(s):  
Large Scale ◽  
Mechanical Performance ◽  
Construction Materials ◽  
Environmental Benefits ◽  
Recycled Aggregates ◽  
Construction And Demolition Wastes ◽  
Short Period ◽  
Natural Aggregates ◽  
Cement Factories ◽  
Made In

Construction and demolition wastes (CDW) are generated at a large scale and have a diversified potential in the construction sector. The replacement of natural aggregates (NA) with CDW recycled aggregates (RA) in construction materials, such as mortars, has several environmental benefits, such as the reduction in the natural resources used in these products and simultaneous prevention of waste landfill. Complementarily, CDW have the potential to capture CO2 since some of their components may carbonate, which also contributes to a decrease in global warming potential. The main objective of this research is to evaluate the influence of the exposure of CDW RA to CO2 produced in cement factories and its effect on mortars. Several mortars were developed with a volumetric ratio of 1:4 (cement: aggregate), with NA (reference mortar), CDW RA and CDW RA exposed to high levels of CO2 (CRA). The two types of waste aggregate were incorporated, replacing NA at 50% and 100% (in volume). The mortars with NA and non-carbonated RA and CRA from CDW were analysed, accounting for their performance in the fresh and hardened states in terms of workability, mechanical behaviour and water absorption by capillarity. It was concluded that mortars with CDW (both CRA and non-carbonated RA) generally present a good performance for non-structural purposes, although they suffer a moderate decrease in mechanical performance when NA is replaced with RA. Additionally, small improvements were found in the performance of the aggregates and mortars with CRA subjected to a CO2 curing for a short period (5 h), while a long carbonation period (5 d) led to a decrease in performance, contrary to the results obtained in the literature that indicate a significant increase in such characteristics. This difference could be because the literature focused on made-in-laboratory CDW aggregates, while, in this research, the wastes came from real demolition activities, and were thus older and more heterogeneous.

scholarly journals Study on bubble-induced turbulence in pipes and containers with Reynolds-stress models

2022 ◽  
Author(s):  
Yixiang Liao ◽  
Tian Ma
Keyword(s):  
Numerical Simulation ◽  
Reynolds Stress ◽  
Large Scale ◽  
Bubbly Flow ◽  
Reynolds Stress Model ◽  
Viscosity Models ◽  
Stress Components ◽  
Specific Source ◽  
Stress Models ◽  
Made In

AbstractBubbly flow still represents a challenge for large-scale numerical simulation. Among many others, the understanding and modelling of bubble-induced turbulence (BIT) are far from being satisfactory even though continuous efforts have been made. In particular, the buoyancy of the bubbles generally introduces turbulence anisotropy in the flow, which cannot be captured by the standard eddy viscosity models with specific source terms representing BIT. Recently, on the basis of bubble-resolving direct numerical simulation data, a new Reynolds-stress model considering BIT was developed by Ma et al. (J Fluid Mech, 883: A9 (2020)) within the Euler—Euler framework. The objective of the present work is to assess this model and compare its performance with other standard Reynolds-stress models using a systematic test strategy. We select the experimental data in the BIT-dominated range and find that the new model leads to major improvements in the prediction of full Reynolds-stress components.

scholarly journals Capitalismo distrettuale, localismi d'impresa, globalizzazione

2008 ◽  
Keyword(s):  
Industrial Development ◽  
Large Scale ◽  
International Markets ◽  
Scope Economies ◽  
North East ◽  
The North ◽  
Productive System ◽  
Dimensional Growth ◽  
It Revolution ◽  
Made In

From the late Sixties on, industrial development in Italy evolved through the spread of small and medium sized firms, aggregated in district networks, with an elevated propensity to enterprise and the marked presence of owner-families. Installed within the local systems, the industrial districts tended to simulate large-scale industry exploiting lower costs generated by factors that were not only economic. The districts are characterised in terms of territorial location (above all the thriving areas of the North-east and Centre) and sector, since they are concentrated in the "4 As" (clothing-fashion, home-decor, agri-foodstuffs, automation-mechanics), with some overlapping with "Made in Italy". How can this model be assessed? This is the crucial question in the debate on the condition and prospects of the Italian productive system between the supporters of its capacity to adapt and the critics of economic dwarfism. A dispassionate judgement suggests that the prospects of "small is beautiful" have been superseded, but that the "declinist" view, that sees only the dangers of globalisation and the IT revolution for our SMEs is risky. The concept of irreversible crisis that prevails at present is limiting, both because it is not easy either to "invent", or to copy, a model of industrialisation, and because there is space for a strategic repositioning of the district enterprises. The book develops considerations in this direction, showing how an evolution of the district model is possible, focusing on: gains in productivity, scope economies (through diversification and expansion of the range of products), flexibility of organisation, capacity to meld tradition and innovation aiming at product quality, dimensional growth of the enterprises, new forms of financing, active presence on the international markets and valorisation of the resources of the territory. It is hence necessary to reactivate the behavioural functions of the entrepreneurs.

scholarly journals Pengaruh Pemahaman Agama terhadap Kinerja Guru Madrasah Ibtidaiah di Kota Manado

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Rivai Bolotio
Keyword(s):  
Data Collection ◽  
Random Sampling ◽  
Teacher Performance ◽  
Descriptive Analysis ◽  
Stratified Random Sampling ◽  
Religious Knowledge ◽  
And Performance ◽  
Positive Direct ◽  
Religious Understanding ◽  
Made In

ABSTRACT, This study aims to examine the influence of religious understanding on the performance of Madrasah Ibtidaiah teachers in Manado City. The method used in this research is correlational quantitative. This research is conducted in Madrasah Ibtidaiah in Manado City with the sample size of 96, selected from 127 teachers using proportional stratified random sampling. Data collection is done by using test and nontest instruments. The test is used to collect data on religious understanding and the nontest is used to collect the data of practice and performance. The collected data are then analyzed using descriptive analysis and path analysis. The results of this study indicate that religious understanding has a positive direct effect on teacher performance. To improve teachers’ performance, the efforts made, in relation to these variables, include improving teachers’ religious understanding by renewing teachers’ religious knowledge by strengthening faith and devotion to God, and increasing selfawareness that obedience and sincerity in applying it are inevitable.Keywords: Religious understanding, performance, teachersPengaruh Pemahaman Agama terhadap Kinerja Guru Madrasah Ibtidaiah di Kota Manado

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