1,846 research outputs found
Forecast of Total Electron Content over Europe for disturbed ionospheric Conditions
A general picture of the occurrence of ionospheric storms as function of local time, season
and location is known from numerous studies over the past 50 years. Nevertheless, it is not
yet possible to say how the ionosphere will actually respond to a given space weather event
because the measurements of the onset time, location of maximum perturbation, amplitude
and type of storm (positive or negative) deviate much from the climatology. However, statistical
analyses of numerous storm events observed in the Total Electron Content (TEC) since 1995
enable to estimate and predict a most probable upcoming perturbed TEC over Europe based
on forecasts of geomagnetic activity. A first approach will be presented here. The forecast of
perturbed TEC is part of the Forecast System Ionosphere build under the umbrella of the FP7
project AFFECTS∗ (Advanced Forecast For Ensuring Communication Through Space). It aims
to help users mitigating the impact on communication system
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Workplace union representation in the British public sector: evidence from the 2011 Workplace Employment Relations Survey.
This paper explores the presence of workplace union representatives in the British public sector, and also the extent to which union representatives are engaged in partnership working with management, drawing on data from the Workplace Employment Relations Survey 2011. This analysis is timely given government plans to introduce reporting requirements and reserve powers to restrict public sector facility time in the Trade Union Bill 2015-16. The analysis finds that in workplaces with union recognition, union representatives are more prevalent and there are more representatives per employee in the public than the private sector, but there is no evidence that this should be viewed as excessive or that managers view it as problematic. There is, on balance, greater evidence of partnership working between union representatives and managers in the public than the private sector. Given the importance of partnership working in improving public services, the results suggest the provisions in the Trade Union Bill 2015-16 relating to public sector facility time are more likely to hinder rather than support public sector managers in their attempts to improve public service provision in the future
A new global model for the ionospheric F2 peak height for radio wave propagation
The F2-layer peak density height <I>hm</I>F2 is one of the most important
ionospheric parameters characterizing HF propagation conditions. Therefore,
the ability to model and predict the spatial and temporal variations of the
peak electron density height is of great use for both ionospheric research
and radio frequency planning and operation. For global <I>hm</I>F2 modelling we
present a nonlinear model approach with 13 model coefficients and a few
empirically fixed parameters. The model approach describes the temporal and
spatial dependencies of <I>hm</I>F2 on global scale. For determining the 13 model
coefficients, we apply this model approach to a large quantity of global <I>hm</I>F2
observational data obtained from GNSS radio occultation measurements onboard
CHAMP, GRACE and COSMIC satellites and data from 69 worldwide ionosonde
stations. We have found that the model fits to these input data with the
same root mean squared (RMS) and standard deviations of 10%. In
comparison with the electron density NeQuick model, the proposed Neustrelitz
global <I>hm</I>F2 model (Neustrelitz Peak Height Model – NPHM) shows percentage
RMS deviations of about 13% and 12% from the observational data during
high and low solar activity conditions, respectively, whereas the
corresponding deviations for the NeQuick model are found 18% and 16%,
respectively
Temporal and spatial distribution of phytoplankton with emphasis on Skeletonema costatum in the Mathamuhuri river – estuary (Chakaria mangrove ecosystem), Bangladesh
A total of 91 species under 44 genera were identified among the phytoplankton community during the course of one year's investigation between May 1982 and April 1983. Bacillariophyta was the most dominant group with 72 specie, Chlorophyta 11 spp, Cyanophyta 6 spp and Pyrrophyta was represented by 2 species. The yearly percentage composition of 4 groups of phytoplankton in order of abundance were Bacillariophyta 50.77%, Cyanophyta 47.70%, Chlorophyta 1.5% and Pyrrophyta 0.02%. The highest densities of phytoplankton were recorded in monsoon months (June-July) with a peak in July (31550 cells/l) and the minimum in February (770 cells/1). Higher concentration of phytoplankton was recorded at station 2, nearer to the Chakaria Sundarbans (mangroves), but abundance of phytoplankton showed no significant difference in the two stations (Mann Whitney U test, P=0.64, Z=-0.642, U=64). Phytoplankton population in this area were positively correlated with rainfall (r=0.655, P=<0.5, df.22) and water temperature (r=0.523, P=<0.05). Skeletonema costatum was the dominant member of phytoplankton and occupied 35.23% of the annual population and occurred throughout the period of study except in September and January. Its abundance was recorded during the monsoon months (April- July) with a maximum density (24185 cells/l) in July. No significant correlation was found between abundance of S. costatum and the hydro-meteorological parameters recorded in the Chakaria mangrove area
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Union representation, collective voice and job quality: an analysis of a survey of union members in the UK finance sector
This article seeks to identify whether employee perceptions of job quality are better in instances where an onsite union representative is present. It also seeks to identify whether the relationship between onsite representative presence and job quality is explained by employee perceptions of union collective voice. The analysis, based on a survey of union members in the UK finance sector, demonstrates that employee perceptions of several dimensions of job quality are better where an onsite representative is present, and that this can be explained by the higher perceptions of union collective voice that onsite representatives engender
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The influence of trade union Disability Champions on employer disability policy and practice
Disability Champions are a new type of lay workplace trade union activist, whose role is to encourage employers to audit and improve disability policies and offer independent advice and guidance on disability issues to employees. Drawing on a survey of the population of Disability Champions, this article assesses Disability Champion influence on employer disability policy and practice. While the majority of Disability Champions report having had a positive impact, they report greater influence on employer willingness to conduct disability audits and to amend and improve employer equal opportunities practices with regard to disability than employer willingness to make reasonable adjustments. The analysis also identifies several factors that are likely to be important in improving Disability Champion effectiveness. Overall, the results suggest Disability Champions have the potential to enhance the ability of unions to represent disabled people and help manage disability issues within the workplace. The article makes a theoretical contribution to Disability Champion roles by further developing the ‘Activity-Support-Characteristic’ framework for the antecedents of new union representatives' effectiveness
Solid behavior of anisotropic rigid frictionless bead assemblies
We investigate the structure and mechanical behavior of assemblies of
frictionless, nearly rigid equal-sized beads, in the quasistatic limit, by
numerical simulation. Three different loading paths are explored: triaxial
compression, triaxial extension and simple shear. Generalizing recent results
[1], we show that the material, despite rather strong finite sample size
effects, is able to sustain a finite deviator stress in the macroscopic limit,
along all three paths, without dilatancy. The shape of the yield surface is
adequately described by a Lade-Duncan (rather than Mohr-Coulomb) criterion.
While scalar state variables keep the same values as in isotropic systems,
fabric and force anisotropies are each characterized by one parameter and are
in one-to-one correspondence with principal stress ratio along all three
loading paths.The anisotropy of the pair correlation function extends to a
distance between bead surfaces on the order of 10% of the diameter. The tensor
of elastic moduli is shown to possess a nearly singular, uniaxial structure
related to stress anisotropy. Possible stress-strain relations in monotonic
loading paths are also discussed
Temperature profile of produced gas in oil palm biomass fluidized bed gasifier: effect of fibre/shell composition ratio
Malaysia is known to be one of the largest palm oil producers and also generates huge amounts of oil palm biomass, which is mainly treated as bio waste. One of the efficient methods to recycle this potential oil palm biomass could be gasification technology. Gasification is a process involving conversion of solid carbonaceous fuel into combustible gas using directly heated biomass. From processing of Fresh Fruit Bunch (FFB) (a biomass example), Empty Fruit Bunch (EFB) fibre, shell etc. are produced. In this study, a laboratory scale fluidized bed was developed, an appropriate fibre/shell composition ratio was studied and analysis on profiles of gas produced in the oil palm biomass fluidized bed gasifier was conducted. The effects of fibre/shell composition ratio and rate of reaction on temperature profiles were investigated. Temperature reaction rate and calorific value of oil palm biomass with gas compositions were also analyzed
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