Considerations on Spark- Gap Channel Radius and Electrical Conductivity

2020 ◽  
Vol 38 (3B) ◽  
pp. 168-176
Author(s):  
Bassam H. Habib
Keyword(s):  
Electrical Conductivity ◽  
Present Model ◽  
Temporal Evolution ◽  
Mathematical Formulation ◽  
Channel Radius ◽  
Spark Gap ◽  
Experimental Parameters ◽  
Constant Quantity ◽  
Spark Channel

A simple phenomenological model is established to determine the temporal evolution of spark gap channel radius and electrical conductivity during the resistive phase period. The present determination is based on the Braginskii’s equation for the channel radius which includes the electrical conductivity of the discharge channel as a constant quantity. In the present model, however, the electrical conductivity is regarded as a time varyingquantity. Basing on this, a mathematical formulation for the channel radius as a function of time was derived, and this has made possible the derivation of an explicit expression for the conductivity as a function of time as well. Taking the temporal average of the electrical conductivity offers an alternative mathematical formulation for the instantaneous radius based on a steady conductivity value that can be determined according to some experimental parameters. It has been verified that both of the channel radius formulations mentioned above lead to similar results for the temporal evolution. The obtained results of the channel radius were used to determine the instantaneous inductance of the spark channel. The present model was used to examine the role of gas pressure and gap width on the temporal evolutions of the channel radius, conductivity, and inductance in nanosecond spark gaps.

Prospective Memory Development Across the Lifespan

2020 ◽  
Vol 25 (3) ◽  
pp. 162-173 ◽  
Author(s):  
Sascha Zuber ◽  
Matthias Kliegel
Keyword(s):  
Prospective Memory ◽  
Healthy Aging ◽  
Present Model ◽  
Current Knowledge ◽  
Well Being ◽  
The Elderly ◽  
Cognitive Factors ◽  
Everyday Functioning ◽  
Integrative Framework

Abstract. Prospective Memory (PM; i.e., the ability to remember to perform planned tasks) represents a key proxy of healthy aging, as it relates to older adults’ everyday functioning, autonomy, and personal well-being. The current review illustrates how PM performance develops across the lifespan and how multiple cognitive and non-cognitive factors influence this trajectory. Further, a new, integrative framework is presented, detailing how those processes interplay in retrieving and executing delayed intentions. Specifically, while most previous models have focused on memory processes, the present model focuses on the role of executive functioning in PM and its development across the lifespan. Finally, a practical outlook is presented, suggesting how the current knowledge can be applied in geriatrics and geropsychology to promote healthy aging by maintaining prospective abilities in the elderly.

ROLE OF ADDED PHOSPHOGYPSUM AND HUMIC ACIDS IN THE KINETIC RELEASE OF SALT FROM SALT AFFECTED SOIL (SALINE – SODIC)

2020 ◽  
pp. 15-27
Keyword(s):  
Electrical Conductivity ◽  
Humic Acids ◽  
Release Rate ◽  
Release Kinetics ◽  
Sodium Adsorption Ratio ◽  
Salt Affected Soil ◽  
Two Factors ◽  
Dissolved Ions ◽  
Kinetic Release

In order to study the effect of phosphogypsum and humic acids in the kinetic release of salt from salt-affected soil, a laboratory experiment was conducted in which columns made from solid polyethylene were 60.0 cm high and 7.1 cm in diameter. The columns were filled with soil so that the depth of the soil was 30 cm inside the column, the experiment included two factors, the first factor was phosphogypsum and was added at levels 0, 5, 10 and 15 tons ha-1 and the second-factor humic acids were added at levels 0, 50, 100 and 150 kg ha-1 by mixing them with the first 5 cm of column soil and one repeater per treatment. The continuous leaching method was used by using an electrolytic well water 2.72 dS m-1. Collect the leachate daily and continue the leaching process until the arrival of the electrical conductivity of the filtration of leaching up to 3-5 dS m-1. The electrical conductivity and the concentration of positive dissolved ions (Ca, Mg, Na) were estimated in leachate and the sodium adsorption ratio (SAR) was calculated. The results showed that the best equation for describing release kinetics of the salts and sodium adsorption ratio in soil over time is the diffusion equation. Increasing the level of addition of phosphogypsum and humic acids increased the constant release velocity (K) of salts and the sodium adsorption ratio. The interaction between phosphogypsum and humic acids was also affected by the constant release velocity of salts and the sodium adsorption ratio. The constant release velocity (K) of the salts and the sodium adsorption ratio at any level of addition of phosphogypsum increased with the addition of humic acids. The highest salts release rate was 216.57 in PG3HA3, while the lowest rate was 149.48 in PG0HA0. The highest release rate of sodium adsorption ratio was 206.09 in PG3HA3, while the lowest rate was 117.23 in PG0HA0.

Power through Intersubjectivity: Representing the Resilient Child in Urban Survival Narratives

2009 ◽  
Vol 2 (1) ◽  
pp. 65-80
Author(s):  
Yvonne Hammer
Keyword(s):  
Social Discourse ◽  
Individual Agency ◽  
Liminal Spaces ◽  
Young Readers ◽  
Problematic Relationship ◽  
Narrative Representations ◽  
Spark Gap ◽  
Urban Survival ◽  
Resilient Child

The problematic relationship between urban dislocation, the proscribed spaces of urban childhood, child marginnalisation and the societal invisibility of under-age citizens is widely thematised in contemporary children's literature. This article examines how childhood agency, as a form of power, becomes aligned with resilience through intersubjectivity in the narrative representations of marginalised child subjects in Virginia Hamilton's The Planet of Junior Brown (1987) and Julie Bertagna's The Spark Gap ( 1996 ). Depictions of child homelessness, which construct resilience in the determination to survive experiences of marginalisation, dislocation and loss, offer an opportunity to examine representations of child subjectivity. This discussion centres on the role of intersubjectivity as an alternative construction to some humanistic frames that privilege the notion of an individual agency divested of childhood's limitations. It identifies the experiential codes which more accurately reflect the choices available to young readers, where liminal spaces of homelessness that first establish social and cultural dependencies are re-interpreted through depictions of relational connection among displaced child subjects. The discussion suggests that these multifocal novels construct dialogic representations of social discourse that affirm intersubjectivity as a form of agency.

scholarly journals The Role of Technology in Greenhouse Agriculture: Towards a Sustainable Intensification in Campo de Dalías (Almería, Spain)

Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 101
Author(s):  
Antonio J. Mendoza-Fernández ◽  
Araceli Peña-Fernández ◽  
Luis Molina ◽  
Pedro A. Aguilera
Keyword(s):  
Land Use ◽  
Economic Development ◽  
Water Resources ◽  
Natural Resources ◽  
Temporal Evolution ◽  
Technological Development ◽  
Sustainable Intensification ◽  
Short Period ◽  
Cultivation Techniques

Campo de Dalías, located in southeastern Spain, is the greatest European exponent of greenhouse agriculture. The development of this type of agriculture has led to an exponential economic development of one of the poorest areas of Spain, in a short period of time. Simultaneously, it has brought about a serious alteration of natural resources. This article will study the temporal evolution of changes in land use, and the exploitation of groundwater. Likewise, this study will delve into the technological development in greenhouses (irrigation techniques, new water resources, greenhouse structures or improvement in cultivation techniques) seeking a sustainable intensification of agriculture under plastic. This sustainable intensification also implies the conservation of existing natural areas.

scholarly journals Using hydraulic head, chloride and electrical conductivity data to distinguish between mountain-front and mountain-block recharge to basin aquifers

2018 ◽  
Vol 22 (2) ◽  
pp. 1629-1648 ◽  
Author(s):  
Etienne Bresciani ◽  
Roger H. Cranswick ◽  
Eddie W. Banks ◽  
Jordi Batlle-Aguilar ◽  
Peter G. Cook ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Arid Regions ◽  
South Australia ◽  
Hydraulic Head ◽  
Mountain Front ◽  
Quaternary Aquifers ◽  
Groundwater Systems ◽  
Flow Directions ◽  
Electrical Conductivity Data

Abstract. Numerous basin aquifers in arid and semi-arid regions of the world derive a significant portion of their recharge from adjacent mountains. Such recharge can effectively occur through either stream infiltration in the mountain-front zone (mountain-front recharge, MFR) or subsurface flow from the mountain (mountain-block recharge, MBR). While a thorough understanding of recharge mechanisms is critical for conceptualizing and managing groundwater systems, distinguishing between MFR and MBR is difficult. We present an approach that uses hydraulic head, chloride and electrical conductivity (EC) data to distinguish between MFR and MBR. These variables are inexpensive to measure, and may be readily available from hydrogeological databases in many cases. Hydraulic heads can provide information on groundwater flow directions and stream–aquifer interactions, while chloride concentrations and EC values can be used to distinguish between different water sources if these have a distinct signature. Such information can provide evidence for the occurrence or absence of MFR and MBR. This approach is tested through application to the Adelaide Plains basin, South Australia. The recharge mechanisms of this basin have long been debated, in part due to difficulties in understanding the hydraulic role of faults. Both hydraulic head and chloride (equivalently, EC) data consistently suggest that streams are gaining in the adjacent Mount Lofty Ranges and losing when entering the basin. Moreover, the data indicate that not only the Quaternary aquifers but also the deeper Tertiary aquifers are recharged through MFR and not MBR. It is expected that this finding will have a significant impact on the management of water resources in the region. This study demonstrates the relevance of using hydraulic head, chloride and EC data to distinguish between MFR and MBR.

Role of Overwintering Forms of Erysiphe necator in Epidemiology of Grapevine Powdery Mildew in Palestinian Vineyards

2014 ◽  
Vol 2 (1) ◽  
pp. 20-25
Author(s):  
Ruba Abuamsha ◽  
Hajaj Hajjeh ◽  
Mazen Salman
Keyword(s):  
Powdery Mildew ◽  
Temporal Evolution ◽  
Control Strategies ◽  
Temporal Distribution ◽  
Field Surveys ◽  
Sequence Characterized Amplified Region ◽  
Grapevine Powdery Mildew ◽  
Fungal Populations ◽  
Bud Breaking

The overwintering modes of E. necator were studied on Palestinian vineyards, through observations on the differentiation and maturation of cleistothecia and on the occurrence of flag-shoots (deriving from overwintering mycelium) in vineyards. Field surveys were carried out in 17 vineyards for the presence of Flag shoots and cleistothecia, both forms were not observed. Genetic structure and composition of E. necator populations were investigated by application of already available SCAR (Sequence Characterized Amplified Region) primers specific for the "flag-shoot" and "ascospore" biotypes. These primers were used to evaluate the dynamics of the spatial and temporal distribution of the two biotypes, into fungal populations present in 8 vineyards, with different cultivars and spray histories, in various Palestinian districts (Hebron, Bethlehem, Jerusalem, Ramallah, Jericho, Nablus, Jenin, Tulkarm). 397 samples were analyzed by the uses of the primer pairs UnE-UnF in PCR reactions. All samples were found to be of the ascospore biotypes. This finding shows that the “flag shoot” biotype, appears soon after bud breaking and disappears later, while the “ascospore” biotype is more frequently associated to later infections and bunches damages. Such information would be helpful to understand the reasons underlying possible temporal evolution of the pathogen's populations in vineyards, and can have important implications for powdery mildew rationale control strategies.

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