How tail reconnection affects the asymmetric state of the magnetosphere in the LFM model

2020 ◽  
Author(s):  
Anders Ohma ◽  
Nikolai Østgaard ◽  
Jone Peter Reistad ◽  
Karl M. Laundal ◽  
Paul Tenfjord
Keyword(s):  
Physical Mechanism ◽  
Plasma Convection ◽  
Symmetric State ◽  
Reconnection Rate ◽  
The North ◽  
System A ◽  
Mhd Simulations ◽  
Current Systems ◽  
Insight Into ◽  
The Imf

<p>The IMF B<sub>y</sub> component is a source of numerous asymmetric features in our magnetospheric system, e.g. north-south asymmetries in the aurora, the magnetospheric and ionospheric current systems and the plasma convection. Several recent studies have shown that asymmetries in the lobe pressure play a major role in inducing these asymmetries. It has also been reported that enhanced tail reconnection affects the dynamics of the system by reducing the north-south asymmetries imposed by the IMF. A possible interpretation of these observations is that enhanced reconnection in the near-Earth tail reduces the pressure in the lobes and thus suppresses the cause of the initial asymmetry. In this study, we present the results from global MHD simulations using the LFM model to further investigate how enhanced tail reconnection affects the asymmetric state of the system. A relaxation of the asymmetry in the closed magnetosphere is seen in the model when the reconnection rate in the tail increases, consistent with observations, and we use the simulation output to gain further insight into the physical mechanism(s) responsible for the return to a more symmetric state.</p>

scholarly journals Effect of the IMF <i>B<sub>y</sub></i> component on the ionospheric flow overhead at EISCAT: observations and theory

2000 ◽  
Vol 18 (12) ◽  
pp. 1503-1522 ◽  
Author(s):  
H. Khan ◽  
S. W. H. Cowley
Keyword(s):  
Magnetic Field ◽  
Local Times ◽  
Plasma Convection ◽  
Flow Perturbation ◽  
The North ◽  
Ionosphere Plasma ◽  
Uncertainty Estimates ◽  
Magnetic Model ◽  
Order Of Magnitude ◽  
The Imf

Abstract. We have analysed a database of ∼300 h of tristatic ionospheric velocity measurements obtained overhead at Tromsø (66.3° magnetic latitude) by the EISCAT UHF radar system, for the presence of flow effects associated with the y-component of the IMF. Since it is already known that the flow depends upon IMF Bz, a least-squares multivariate analysis has been used to determine the flow dependence on both IMF By and Bz simultaneously. It is found that significant flow variations with IMF By occur, predominantly in the midnight sector (∼2100–0300 MLT), but also pre-dusk (∼1600–1700 MLT), which are directed eastward for IMF By positive and westward for IMF By negative. The flows are of magnitude 20–30 m s–1 nT–1 in the midnight sector, and smaller, 10–20 m s–1 nT–1, pre-dusk, and are thus associated with significant changes of flow of order a few hundred m s–1 over the usual range of IMF By of about ±5 nT. At other local times the IMF By-related perturbation flows are much smaller, less than ∼5 m s–1 nT–1, and consistent with zero within the uncertainty estimates. We have investigated whether these IMF By-dependent flows can be accounted for quantitatively by a theoretical model in which the equatorial flow in the inner magnetosphere is independent of IMF By, but where distortions of the magnetospheric magnetic field associated with a "penetrating" component of the IMF By field changes the mapping of the field to the ionosphere, and hence the ionospheric flow. We find that the principal flow perturbation produced by this effect is an east-west flow whose sense is determined by the north-south component of the unperturbed flow. Perturbations in the north-south flow are typically smaller by more than an order of magnitude, and generally negligible in terms of observations. Using equatorial flows which are determined from EISCAT data for zero IMF By, to which the corotation flow has been added, the theory predicts the presence of zonal perturbation flows which are generally directed eastward in the Northern Hemisphere for IMF By positive and westward for IMF By negative at all local times. However, although the day and night effects are therefore similar in principle, the model perturbation flows are much larger on the nightside than on the dayside, as observed, due to the day-night asymmetry in the unperturbed magnetospheric magnetic field. Overall, the model results are found to account well for the observed IMF By-related flow perturbations in the midnight sector, in terms of the sense and direction of the flow, the local time of their occurrence, as well as the magnitude of the flows (provided the magnetic model employed is not too distorted from dipolar form). At other local times the model predicts much smaller IMF By-related flow perturbations, and thus does not account for the effects observed in the pre-dusk sector.Key words: Magnetospheric physics (magnetosphere · ionosphere interactions) – Ionosphere (plasma convection; auroral ionosphere)

Chinese Historiography in the Age of Maturity, 960–1368

2018 ◽  
Author(s):  
Charles Hartman
Keyword(s):  
South China ◽  
Song Dynasty ◽  
Political Power ◽  
Examination System ◽  
Economic Expansion ◽  
New Class ◽  
The Song Dynasty ◽  
The North ◽  
System A ◽  
Age Of Maturity

This chapter looks at how the Song dynasty (960–1279) reconsolidated central power and eliminated the provincial regimes that had developed in the wake of Tang decentralization. During the first thirty years after 960, they fostered astute policies that promoted and took advantage of continuing economic expansion. To administer their new polity, the Song emperors recruited through the examination system a new class of bureaucratic elite that Western writings on China often call the ‘literati’. The aristocrats of Tang had given way to the merchants and bureaucrats of Song. However, although the Song expanded Chinese economic and political power into South China, it never completed the conquest of all the traditional Chinese lands in the north. The Song coexisted with a series of alien or conquest dynasties to its north and west.

Professionals freaking out: the case of accreditation in Dutch higher education

2009 ◽  
Vol 21 (5) ◽  
pp. 473-485 ◽  
Author(s):  
Everard van Kemenade ◽  
Teun W. Hardjono
Keyword(s):  
The Netherlands ◽  
Design Methodology ◽  
Iso 9000 ◽  
Preliminary Survey ◽  
External Evaluation ◽  
Content Type ◽  
Evaluation Systems ◽  
System A ◽  
Engineering And Technology ◽  
Insight Into

PurposeThe purpose of this paper is to define what factors cause willingness and/or resistance among lecturers in universities towards external evaluation systems, especially accreditation.Design/methodology/approachA model has been designed to describe possible factors of willingness and/or resistance towards accreditation based on Ajzen and Metselaar. A literature review has been undertaken on the effects of external evaluation like ISO 9000 as well as accreditation systems such as Accreditation Board for Engineering and Technology and European Quality Improvement System. A questionnaire has been administered to a group of 63 lecturers from three departments at Fontys University in The Netherlands. The results of this preliminary survey have been presented to 1,500 academics in The Netherlands and Flanders to collect empirical data.FindingsResistance to accreditation can be found in the consequences of accreditation for the work of the lecturer (workload), negative emotions (stress and insecurity); the lack of knowledge and experience (help from specialists is needed); and lack of acceptance (other paradigm).Originality/valueThe paper provides more insight into the difficulties that organizations, especially universities, have to commit their employees to external evaluation. It might be possible to generalize the findings to other professionals in other organizations. Little research in this field has been undertaken so far.

Response time of the high-latitude dayside ionosphere to sudden changes in the north-south component of the IMF

1988 ◽  
Vol 36 (12) ◽  
pp. 1415-1428 ◽  
Author(s):  
H. Todd ◽  
S.W.H. Cowley ◽  
M. Lockwood ◽  
D.M. Willis ◽  
H. Lühr
Keyword(s):  
Response Time ◽  
High Latitude ◽  
The North ◽  
The Imf

scholarly journals Machine Learning and Sensor Fusion for Estimating Continuous Energy Expenditure

AI Magazine ◽  
2012 ◽  
Vol 33 (2) ◽  
pp. 55 ◽  
Author(s):  
Nisarg Vyas ◽  
Jonathan Farringdon ◽  
David Andre ◽  
John Ivo Stivoric
Keyword(s):  
Machine Learning ◽  
Energy Expenditure ◽  
Sensor Data ◽  
Machine Learning Techniques ◽  
Sensor Technology ◽  
Health Goals ◽  
System A ◽  
Multi Sensor Data Fusion ◽  
Learning Techniques ◽  
Insight Into

In this article we provide insight into the BodyMedia FIT armband system — a wearable multi-sensor technology that continuously monitors physiological events related to energy expenditure for weight management using machine learning and data modeling methods. Since becoming commercially available in 2001, more than half a million users have used the system to track their physiological parameters and to achieve their individual health goals including weight-loss. We describe several challenges that arise in applying machine learning techniques to the health care domain and present various solutions utilized in the armband system. We demonstrate how machine learning and multi-sensor data fusion techniques are critical to the system’s success.

scholarly journals IMF effect on the polar cap contraction and expansion during a period of substorms

2013 ◽  
Vol 31 (6) ◽  
pp. 1021-1034 ◽  
Author(s):  
A. T. Aikio ◽  
T. Pitkänen ◽  
I. Honkonen ◽  
M. Palmroth ◽  
O. Amm
Keyword(s):  
Recovery Phase ◽  
Bow Shock ◽  
Polar Cap ◽  
Reconnection Rate ◽  
Early Recovery ◽  
Mhd Simulation ◽  
Expansion Phase ◽  
Contraction And Expansion ◽  
Good Agreement ◽  
The Imf

Abstract. The polar cap boundary (PCB) location and motion in the nightside ionosphere has been studied by using measurements from the EISCAT radars and the MIRACLE magnetometers during a period of four substorms on 18 February 2004. The OMNI database has been used for observations of the solar wind and the Geotail satellite for magnetospheric measurements. In addition, the event was modelled by the GUMICS-4 MHD simulation. The simulation of the PCB location was in a rather good agreement with the experimental estimates at the EISCAT longitude. During the first three substorm expansion phases, neither the local observations nor the global simulation showed any poleward motions of the PCB, even though the electrojets intensified. Rapid poleward motions of the PCB took place only in the early recovery phases of the substorms. Hence, in these cases the nightside reconnection rate was locally higher in the recovery phase than in the expansion phase. In addition, we suggest that the IMF Bz component correlated with the nightside tail inclination angle and the PCB location with about a 17-min delay from the bow shock. By taking the delay into account, the IMF northward turnings were associated with dipolarizations of the magnetotail and poleward motions of the PCB in the recovery phase. The mechanism behind this effect should be studied further.

scholarly journals Probabilistic assessment of nectar requirements for nectar-foraging honey bees

Apidologie ◽  
2019 ◽  
Vol 51 (2) ◽  
pp. 180-200 ◽  
Author(s):  
Sara Rodney ◽  
Vincent J. Kramer
Keyword(s):  
Honey Bee ◽  
Honey Bees ◽  
Dietary Exposure ◽  
Food Storage ◽  
Regulatory Agencies ◽  
American Government ◽  
The North ◽  
Dietary Requirements ◽  
Bee Colonies ◽  
Insight Into

AbstractRecent concerns regarding potential effects of pesticides on pollinators have prompted regulatory agencies to estimate dietary ingestion rates for honey bees (Apis mellifera). The task is difficult because of the complex caste and food storage systems in honey bee colonies. Considerable data on the nutrition and energetics of honey bees have recently been collated. These data were used to parameterize a probabilistic model estimating nectar requirements of nectar foragers. Median estimates were more than 6× lower than the recommended median value from the North American government agencies, of 292 mg nectar/bee/day. The distribution of estimates had much greater variability than those of the agencies. The differences are due primarily to the disparate assumptions regarding how much time nectar foragers spend flying and foraging. Risk assessors considering honey bee dietary exposure should take account of current and emerging data providing insight into nectar forager dietary requirements, foraging activity, and feeding behavior.

scholarly journals 3D reconstruction of syn-tectonic strata in a salt-related orogen: learnings from the Llert syncline (South-central Pyrenees)

2020 ◽  
Vol 18 ◽  
pp. 1-19
Author(s):  
Adrià Ramos ◽  
Berta Lopez-Mir ◽  
Elisabeth P. Wilson ◽  
Pablo Granado ◽  
Josep Anton Muñoz
Keyword(s):  
3D Reconstruction ◽  
Field Research ◽  
Rift System ◽  
Passive Margins ◽  
Fold System ◽  
The North ◽  
Structural Framework ◽  
South Central ◽  
Insight Into ◽  
Central Pyrenees

The Llert syncline is located in the South-central Pyrenees, between the eastern termination of the EW-trending Cotiella Basin and the north-western limb of the NS-trending Turbón-Serrado fold system. The Cotiella Basin is an inverted upper Coniacian-lower Santonian salt-floored post-rift extensional basin developed along the northern Iberian rift system. The Turbón-Serrado fold system consists of upper Santonian – Maastrichtian contractional salt-cored anticlines developed along an inverted transfer zone of the Pyrenean rift system. Based on field research, this paper presents a 3D reconstruction of the Llert syncline in order to further constrain the transition between these oblique salt-related structures. Our results suggest that the evolution of the Llert syncline was mainly controlled by tectonic shortening related to the tectonic inversion of the Cotiella Basin synchronously to the growth of the Turbón-Serrado detachment anticline, and by the pre-compressional structural framework of the Pyrenean rift system. Our contribution provides new insight into the geometric and kinematic relationships of structures developed during the inversion of passive margins involving salt.

scholarly journals The North-South Gas Corridor in the Context of Poland’s Gas Transmission System—A Perfect Opportunity to Diversify Gas Resources

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7188
Author(s):  
Wiktor Hebda
Keyword(s):  
Energy Security ◽  
Field Research ◽  
Green Energy ◽  
Coal Production ◽  
The North ◽  
System A ◽  
State Of Affairs ◽  
High Level ◽  
Huge Challenge ◽  
Gas Supply

The energy sector in Poland is currently calling for dynamic redevelopment and cleaner energy. This country is world famous for its high level of coal production, from which it does not want to retreat in the next two decades. For this reason, it is safer to gradually reduce the use of coal while increasing the consumption of gas and simultaneously developing green energy. However, the Polish gas sector is still dependent on Russian gas supplied through the Yamal gas pipeline. Taking into consideration Polish geopolitics, this state of affairs poses a huge challenge and a threat to Poland’s energy security. That is why the concept of the North-South Gas Corridor was introduced. It is intended to be a network of gas pipelines that connect the countries of Central and South Europe to two gas terminals (in Poland and Croatia), which will supply gas from a chosen source. This article presents the current condition of the gas sector in Poland. It focuses on the North-South Gas Corridor project and its impact on the energy security of Poland. An analysis of documents and field research shows that the North-South Gas Corridor provides Poland with an opportunity to diversify the sources and directions of gas supply over the next few years.

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