scholarly journals Instability of sheared density interfaces

2018 ◽  
Vol 860 ◽  
pp. 145-171 ◽  
Author(s):  
T. S. Eaves ◽  
N. J. Balmforth
Keyword(s):  
Travelling Waves ◽  
Linear Instability ◽  
The Other ◽  
Flow Instabilities ◽  
Small Scale ◽  
Flow Profile ◽  
Large Bulk ◽  
Density Interfaces ◽  
Stratified Shear Flow ◽  
High Prandtl Number

Of the canonical flow instabilities (Kelvin–Helmholtz, Holmboe-wave and Taylor–Caulfield) of stratified shear flow, the Taylor–Caulfield instability (TCI) has received relatively little attention, and forms the focus of the current study. First, a diagnostic of the linear instability dynamics is developed that exploits the net pseudomomentum to distinguish TCI from the other two instabilities for any given flow profile. Second, the nonlinear dynamics of TCI is studied across its range of unstable horizontal wavenumbers and bulk Richardson numbers using numerical simulation. At small bulk Richardson numbers, a cascade of billow structures of sequentially smaller size may form. For large bulk Richardson numbers, the primary nonlinear travelling waves formed by the linear instability break down via a small-scale, Kelvin–Helmholtz-like roll-up mechanism with an associated large amount of mixing. In all cases, secondary parasitic nonlinear Holmboe waves appear at late times for high Prandtl number. Third, a nonlinear diagnostic is proposed to distinguish between the saturated states of the three canonical instabilities based on their distinctive density–streamfunction and generalised vorticity–streamfunction relations.

scholarly journals Analysis of Operational Efficiencies and Costs for Extracting Thinned Woods in Small-Scale Forestry, Nasunogahara Area, Tochigi Prefecture, Japan

2020 ◽  
Vol 3 (1) ◽  
pp. 61
Author(s):  
Kazuhiro Aruga
Keyword(s):  
Transportation Costs ◽  
The Other ◽  
Small Scale ◽  
Light Truck ◽  
Operation Costs ◽  
Other Hand ◽  
Light Trucks ◽  
The Cost ◽  
Manual Extraction ◽  
Truck Transportation

In this study, two operational methodologies to extract thinned woods were investigated in the Nasunogahara area, Tochigi Prefecture, Japan. Methodology one included manual extraction and light truck transportation. Methodology two included mini-forwarder forwarding and four-ton truck transportation. Furthermore, a newly introduced chipper was investigated. As a result, costs of manual extractions within 10 m and 20 m were JPY942/m3 and JPY1040/m3, respectively. On the other hand, the forwarding cost of the mini-forwarder was JPY499/m3, which was significantly lower than the cost of manual extractions. Transportation costs with light trucks and four-ton trucks were JPY7224/m3 and JPY1298/m3, respectively, with 28 km transportation distances. Chipping operation costs were JPY1036/m3 and JPY1160/m3 with three and two persons, respectively. Finally, the total costs of methodologies one and two from extraction within 20 m to chipping were estimated as JPY9300/m3 and JPY2833/m3, respectively, with 28 km transportation distances and three-person chipping operations (EUR1 = JPY126, as of 12 August 2020).

scholarly journals Theology at Thresholds: Learning from a Practice ‘In Transition’

2017 ◽  
Vol 4 (1) ◽  
pp. 45-62 ◽  
Author(s):  
Rachel Muers ◽  
Rhiannon Grant
Keyword(s):  
Decision Making ◽  
The Other ◽  
Small Scale ◽  
Theological Ethics ◽  
Reciprocal Influence ◽  
Core Practices ◽  
Recent Developments ◽  
Collective Process ◽  
The One ◽  
Over Time

Recent developments in contemporary theology and theological ethics have directed academic attention to the interrelationships of theological claims, on the one hand, and core community-forming practices, on the other. This article considers the value for theology of attending to practice at the boundaries, the margins, or, as we prefer to express it, the threshold of a community’s institutional or liturgical life. We argue that marginal or threshold practices can offer insights into processes of theological change – and into the mediation between, and reciprocal influence of, ‘church’ and ‘world’. Our discussion focuses on an example from contemporary British Quakerism. ‘Threshing meetings’ are occasions at which an issue can be ‘threshed out’ as part of a collective process of decision-making. Drawing on a 2015 small-scale study (using a survey and focus group) of British Quaker attitudes to and experiences of threshing meetings, set in the wider context of Quaker tradition, we interpret these meetings as a space for working through – in context and over time – tensions within Quaker theology, practice and self-understandings, particularly those that emerge within, and in relation to, core practices of Quaker decision-making.

Justification of resource-own technologies and technical equipment for preparing fodder on small livestock farms

2021 ◽  
Vol 07 (02) ◽  
pp. 36-42
Author(s):  
Ləman Faiq qızı Verdiyeva ◽  
Keyword(s):  
The Other ◽  
Small Scale ◽  
Technical Equipment ◽  
Natural Factors ◽  
Livestock Farms ◽  
Small Livestock ◽  
The One ◽  
Peasant Farmers ◽  
Large Farms ◽  
Livestock Development

In the current situation, if the characteristic feature of livestock development is, on the one hand, related to the diversification of agriculture, on the other hand it is also associated with the production of various forms of ownership in the country, large farms and small private farms. At present, interrelated financial, technological, social and natural factors remain in our country as factors limiting the development of small-scale livestock farms. However, it should be noted that despite the lack of opportunities and material and technical support, small farms, peasant farmers and households currently produce more than 80% of meat and milk in our country.

scholarly journals The development of small scale farming: two cases from the Commonwealth Caribbean.

1968 ◽  
Vol 16 (4) ◽  
pp. 264-274
Author(s):  
D.T. Edwards
Keyword(s):  
Environmental Changes ◽  
The Other ◽  
Small Scale ◽  
Government Agencies ◽  
Rapid Rate ◽  
The Face ◽  
Market Gardening ◽  
Commonwealth Caribbean ◽  
The Government

Two very different cases of small-scale farm development in the Commonwealth Caribbean are reviewed. One is Jamaican small farming, which responded little to considerable efforts made for its improvement by the Government agencies. The other is market gardening at Aranjuez, Trinidad where production grew at an extremely rapid rate in the face of intense and antagonistic competition between the market gardeners and without significant direct assistance by official agencies. The conclusions include a number of possible strategies for farm development, comprising individual or collective persuasion, coercion, creation of new farms, and environmental changes. T. A. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The Perks and Perils of Interdisciplinary Research

2018 ◽  
Vol 26 (S2) ◽  
pp. S55-S67 ◽  
Author(s):  
Erin Leahey
Keyword(s):  
Interdisciplinary Research ◽  
Large Scale ◽  
Policy Implications ◽  
The Other ◽  
Small Scale ◽  
Extra Time ◽  
Empirical Assessment ◽  
Cognitive Challenges

This paper synthesizes findings from two studies the author conducted that examine how engagement in interdisciplinary research (IDR) influences scholars’ careers. Results from these two studies, one large-scale and quantitative and the other small-scale and qualitative, provide a much needed empirical assessment of IDR’s effects on individual careers. In essence, they provide a nice antidote (and some caution) to the rhetoric and enthusiasm surrounding IDR. My co-authors of these studies and I find that engaging in interdisciplinary research increases a scholar’s visibility in terms of citations, but also presents challenges, including reduced productivity, cognitive challenges, lack of support, extra time and commitment, and framing of one’s work. This paper concludes by discussing the policy implications of this research.

scholarly journals Analysis of Small-Scale Fading Distributions in Vehicle-to-Vehicle Communications

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Vicent M. Rodrigo-Peñarrocha ◽  
Juan Reig ◽  
Lorenzo Rubio ◽  
Herman Fernández ◽  
Susana Loredo
Keyword(s):  
Goodness Of Fit ◽  
Urban Environments ◽  
The Other ◽  
Small Scale ◽  
Channel Measurements ◽  
Experimental Distribution ◽  
Vehicle To Vehicle ◽  
Kolmogorov Smirnov ◽  
Inference Techniques ◽  
The City

This work analyzes the characteristics of the small-scale fading distribution in vehicle-to-vehicle (V2V) channels. The analysis is based on a narrowband channel measurements campaign at 5.9 GHz designed specifically for that purpose. The measurements were carried out in highway and urban environments around the city of Valencia, Spain. The experimental distribution of the small-scale fading is compared to several analytical distributions traditionally used to model the fast fading in wireless communications, such as Rayleigh, Nakagami-m, Weibull, Rice, andα-μdistributions. The parameters of the distributions are derived through statistical inference techniques and their goodness-of-fit is evaluated using the Kolmogorov-Smirnov (K-S) test. Our results show that theα-μdistribution exhibits a better fit compared to the other distributions, making its use interesting to model the small-scale fading in V2V channels.

scholarly journals A journey of a thousand miles begins with one small step – human agency, hydrological processes and time in socio-hydrology

2013 ◽  
Vol 10 (11) ◽  
pp. 14265-14304 ◽  
Author(s):  
M. W. Ertsen ◽  
J. T. Murphy ◽  
L. E. Purdue ◽  
T. Zhu
Keyword(s):  
Decision Making ◽  
Social Action ◽  
Human Agency ◽  
The Other ◽  
Social Structures ◽  
Small Scale ◽  
Small Step ◽  
Time Step ◽  
Human Decision ◽  
Day To Day Operations

Abstract. When simulating social action in modeling efforts, as in socio-hydrology, an issue of obvious importance is how to ensure that social action by human agents is well-represented in the analysis and the model. Generally, human decision-making is either modeled on a yearly basis or lumped together as collective social structures. Both responses are problematic, as human decision making is more complex and organizations are the result of human agency and cannot be used as explanatory forces. A way out of the dilemma how to include human agency is to go to the largest societal and environmental clustering possible: society itself and climate, with time steps of years or decades. In the paper, the other way out is developed: to face human agency squarely, and direct the modeling approach to the human agency of individuals and couple this with the lowest appropriate hydrological level and time step. This approach is supported theoretically by the work of Bruno Latour, the French sociologist and philosopher. We discuss irrigation archaeology, as it is in this discipline that the issues of scale and explanatory force are well discussed. The issue is not just what scale to use: it is what scale matters. We argue that understanding the arrangements that permitted the management of irrigation over centuries, requires modeling and understanding the small-scale, day-to-day operations and personal interactions upon which they were built. This effort, however, must be informed by the longer-term dynamics as these provide the context within which human agency, is acted out.

Influence of nozzle external geometry on wavepackets in under-expanded supersonic impinging jets

2021 ◽  
Vol 929 ◽  
Author(s):  
Shahram Karami ◽  
Julio Soria
Keyword(s):  
Shear Layer ◽  
Spectral Decomposition ◽  
Travelling Waves ◽  
Near Field ◽  
High Amplitude ◽  
Impinging Jets ◽  
The Other ◽  
Mode Shapes ◽  
Reflected Shock ◽  
Spatial Modes

In this study, large-eddy simulations are utilised to unravel the influence of the nozzle's external geometry on upstream-travelling waves in under-expanded supersonic impinging jets. Three configurations, a thin-lipped, a thin-lipped with a sponge and an infinite-lipped nozzle are considered with the other non-dimensionalised geometrical and flow variables identical for the three cases. Spectral proper orthogonal decomposition is applied to the Mack norm, i.e. the energy norm based on the stagnation energy, to obtain the spatial modes at their corresponding frequency. The spectral decomposition of the spatial modes at optimal and suboptimal frequencies is used to isolate the wavepackets into upstream- and downstream-propagating waves based on their phase velocity. It is found that the external geometry of the nozzle has a significant influence on the first-order statistics even though the governing non-dimensional parameters are the same for all three cases. Multiple peaks emerge in the energy spectra at distinct frequencies corresponding to axisymmetric azimuthal modes for each case. The downstream-propagating wavepackets have a high amplitude at the shear layer of the three jets with the mode shapes resembling Kelvin–Helmholtz instability waves, while the upstream-travelling wavepackets exist in the three regions of the near field, shear layer and inside of the jet. The barrel shock at the nozzle exit appears as a flexible shield, which prevents upstream-travelling waves from reaching the internal region of the nozzle, where the upstream-travelling waves travel obliquely with one side of the wavefront is crawling on the reflected shock while the other side is guided by the shear layer. These latter waves can reach the nozzle lip via inside of the jet. The spectral decomposition of the spatial modes at optimal and suboptimal frequencies show that all three forms of the near field, shear layer and inside jet upstream-travelling wavepackets contribute to the receptivity process while their contributions and strength are altered by the change of the external geometry of the nozzle.

scholarly journals Balanced reconnection intervals: four case studies

2008 ◽  
Vol 26 (12) ◽  
pp. 3897-3912 ◽  
Author(s):  
A. D. DeJong ◽  
A. J. Ridley ◽  
C. R. Clauer
Keyword(s):  
Case Studies ◽  
Large Scale ◽  
The Other ◽  
Small Scale ◽  
Polar Cap ◽  
Reconnection Rate ◽  
Magnetospheric Convection ◽  
The Third ◽  
New Name ◽  
Definition Of

Abstract. During steady magnetospheric convection (SMC) events the magnetosphere is active, yet there are no data signatures of a large scale reconfiguration, such as a substorm. While this definition has been used for years it fails to elucidate the true physics that is occurring within the magnetosphere, which is that the dayside merging rate and the nightside reconnection rate balance. Thus, it is suggested that these events be renamed Balanced Reconnection Intervals (BRIs). This paper investigates four diverse BRI events that support the idea that new name for these events is needed. The 3–4 February 1998 event falls well into the classic definition of an SMC set forth by Sergeev et al. (1996), while the other challenge some previous notions about SMCs. The 15 February 1998 event fails to end with a substorm expansion and concludes as the magnetospheric activity slowly quiets. The third event, 22–23 December 2000, begins with a slow build up of magnetospheric activity, thus there is no initiating substorm expansion. The last event, 17 February 1998, is more active (larger AE, AL and cross polar cap potential) than previously studied SMCs. It also has more small scale activity than the other events studied here.

A Study of the Effect of Standard Laboratory Processing on Speed and Resolution of Three Black and White Aerial Films

1983 ◽  
Vol 37 (1) ◽  
pp. 3-10
Author(s):  
E. A. Fleming ◽  
M. Landreville ◽  
E. Nagy
Keyword(s):  
Type A ◽  
The Other ◽  
Small Scale ◽  
High Contrast ◽  
Aerial Photo ◽  
Standard Laboratory ◽  
Average Gradient ◽  
Black And White ◽  
Contrast Range ◽  
Film Speed

Three aerial films were tested using standard aerial photo laboratory processing procedures for three different chemistries. Relationships were established with respect to average gradient, speed, base plus fog, graininess and resolution for low, medium and high contrast targets. The films compared were Kodak Double-X type 2405, Kodak Plus-X type 2402 and Kodak Panatomic-X 2412. The processing was done in a Kodak Versamat processor using Type A, 885 and Versaflo chemistry. The results indicated that processing in 885 chemistry enhanced film speed. The versatility of Double-X in terms of speed and contrast range was demonstrated, however the resolution of Panatomic-X greatly exceeded that of either of the other two films and shows promise for small scale mapping photography.

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