scholarly journals Quasi-Steady Flow in Hydraulic Systems Using MOC

2000 ◽  
Author(s):  
E. Benjamin Wylie
Keyword(s):  
Steady Flow ◽  
Method Of Characteristics ◽  
Hydraulic Systems ◽  
Flow Problems ◽  
Alternative Approach ◽  
Unique Approach ◽  
A Minor ◽  
Almost All ◽  
Recent Attention

The Method of Characteristics (MOC) is utilized effectively in many industries to calculate hydraulic transients in almost all pipeline systems. Recently it has been suggested as a suitable calculation procedure for long term (extended time) quasi-steady flow problems. It might serve as an alternative approach to using rigid water-column (lumped inertia) calculations, or to integrating over time with a series of steady state calculations, which are two procedures receiving recent attention. This paper provides a unique approach within the MOC framework, by modifying terms in the pipeline partial differential equations. When carried through the MOC it leads to a minor modification in a transient code by introducing the two new parameters. The method is developed and applied to a network example herein.

Fear of Gynarchy in an Age of Chaos: Kong Qi's Reflections on Life in South China under Mongol Rule

1998 ◽  
Vol 41 (1) ◽  
pp. 1-95 ◽  
Author(s):  
Paul Smith
Keyword(s):  
Steady Flow ◽  
Natural Disaster ◽  
Civil Wars ◽  
South China ◽  
Provincial Government ◽  
Southern Song ◽  
A Minor ◽  
Special Circumstances ◽  
Dynastic Cycle

AbstractOver the long term, the Mongol conquest of the Southern Song in 1276 was less destructive to members of the local South Chinese elite than was the failure of the Yuan regime to establish strong and durable institutions of dynastic rule. For not long after the elite survivors of the Sino-Mongol wars had returned to a comfortable prosperity under Yuan rule, their children were buffetted by the instability and civil wars that engulfed Yuan society from the late 1330s to the collapse of the dynasty in 1368. The Kongs of Liyang typify many of the most salient features of elite life in South China under the compressed Yuan dynastic cycle: the orphaned son of a minor Song official who immediately capitulated to the Mongols, by the 1320s Kong Wensheng had translated talent, pedigree, and his position as a respected clerk in provincial government into such accoutrements of elite Yuan life as a library, sojourning literati guests, and a steady flow of slaves and bondservants thrown onto the market by penury and natural disaster. The prosperity built up by men like Kong Wensheng unravelled in the last tumultuous decades of the Yuan, an era of chaos that is captured by Wensheng's son Kong Qi in his Frank Recollections of the Zhizheng Era of ca. 1365. Even as it exemplifies many aspects of the compressed Yuan dynastic cycle, this collection of cautionary anecdotes and observations is also colored by Kong Qi's special circumstances as a minor son and a uxorilocal husband, circumstances that incline Kong Qi to blame the perils of his family, his society, and ultimately his dynasty on women's usurpation of male-centered institutions of public authority to create their own private gynarchies. Kong's jeremiads against usurpatious women in turn raise the possibility that during the Yuan, if not at all times, women exercised far more power and autonomy than normative prescriptions would suggest.

Is 3 years adequate for tracking completely occluded coiled aneurysms?

2020 ◽  
Vol 133 (3) ◽  
pp. 758-764
Author(s):  
Eung Koo Yeon ◽  
Young Dae Cho ◽  
Dong Hyun Yoo ◽  
Su Hwan Lee ◽  
Hyun-Seung Kang ◽  
...  
Keyword(s):  
De Novo ◽  
Careful Monitoring ◽  
Surveillance Period ◽  
Radiological Data ◽  
De Novo Aneurysm ◽  
Low Probability ◽  
Almost All ◽  
Annual Risk

OBJECTIVEThe authors conducted a study to ascertain the long-term durability of coiled aneurysms completely occluded at 36 months’ follow-up given the potential for delayed recanalization.METHODSIn this retrospective review, the authors examined 299 patients with 339 aneurysms, all shown to be completely occluded at 36 months on follow-up images obtained between 2011 and 2013. Medical records and radiological data acquired during the extended monitoring period (mean 74.3 ± 22.5 months) were retrieved, and the authors analyzed the incidence of (including mean annual risk) and risk factors for delayed recanalization.RESULTSA total of 5 coiled aneurysms (1.5%) occluded completely at 36 months showed recanalization (0.46% per aneurysm-year) during the long-term surveillance period (1081.9 aneurysm-years), 2 surfacing within 60 months and 3 developing thereafter. Four showed minor recanalization, with only one instance of major recanalization. The latter involved the posterior communicating artery as an apparent de novo lesion, arising at the neck of a firmly coiled sac, and was unrelated to coil compaction or growth. Additional embolization was undertaken. In a multivariate analysis, a second embolization for a recurrent aneurysm (HR = 22.088, p = 0.003) independently correlated with delayed recanalization.CONCLUSIONSAlmost all coiled aneurysms (98.5%) showing complete occlusion at 36 months postembolization proved to be stable during extended observation. However, recurrent aneurysms were predisposed to delayed recanalization. Given the low probability yet seriousness of delayed recanalization and the possibility of de novo aneurysm formation, careful monitoring may be still considered in this setting but at less frequent intervals beyond 36 months.

Similarity problems of the theory of unsteady concentration boundary layer

1983 ◽  
Vol 48 (10) ◽  
pp. 2751-2766
Author(s):  
Ondřej Wein ◽  
N. D. Kovalevskaya
Keyword(s):  
Boundary Layer ◽  
Approximate Method ◽  
Steady Flow ◽  
Broad Class ◽  
Concentration Boundary Layer ◽  
Concentration Change ◽  
Concentration Boundary ◽  
Flow Problems

Using a new approximate method, transient course of the local and mean diffusion fluxes following a step concentration change on the wall has been obtained for a broad class of steady flow problems.

The geography of climate migration

2021 ◽  
pp. 1-37
Author(s):  
Michał Burzyński ◽  
Frédéric Docquier ◽  
Hendrik Scheewel
Keyword(s):  
Climate Change ◽  
International Migration ◽  
First Century ◽  
Long Term Effects ◽  
Mobility Data ◽  
Rural And Urban ◽  
Working Age ◽  
Internal Mobility ◽  
Almost All

Abstract In this paper, we investigate the long-term effects of climate change on the mobility of working-age people. We use a world economy model that covers almost all the countries around the world, and distinguishes between rural and urban regions as well as between flooded and unflooded areas. The model is calibrated to match international and internal mobility data by education level for the last 30 years, and is then simulated under climate change variants. We endogenize the size, dyadic, and skill structure of climate migration. When considering moderate climate scenarios, we predict mobility responses in the range of 70–108 million workers over the course of the twenty-first century. Most of these movements are local or inter-regional. South–South international migration responses are smaller, while the South–North migration response is of the “brain drain” type and induces a permanent increase in the number of foreigners in OECD countries in the range of 6–9% only. Changes in the sea level mainly translate into forced local movements. By contrast, inter-regional and international movements are sensitive to temperature-related changes in productivity. Lastly, we show that relaxing international migration restrictions may exacerbate the poverty effect of climate change at origin if policymakers are unable to select/screen individuals in extreme poverty.

scholarly journals The Demerger Impact upon Sustainable Development of Economic Entities: Evidence from Romania

2021 ◽  
Vol 13 (15) ◽  
pp. 8316
Author(s):  
Camelia Mirela Baba ◽  
Constantin Duguleană ◽  
Marius Sorin Dincă ◽  
Liliana Duguleană ◽  
Gheorghița Dincă
Keyword(s):  
Sustainable Development ◽  
Business Strategies ◽  
The Sustainable Development ◽  
Ex Post ◽  
Before And After ◽  
Almost All ◽  
The Impact ◽  
Profitability Ratios ◽  
Positive Effect

The Covid-19 induced economic crisis has significantly affected almost all businesses from nearly every sector, causing severe financial problems, lack of cash assets, and decrease of revenues. In this context, the economic entities were forced to look for adjustment and rescue solutions of their activities. One possible solution for the recovery and reorganization of economic entities’ activities is demerger. This paper evaluates the impact of demerger upon the sustainable development of economic entities in terms of economic efficiency and financial performances. To achieve this goal, a statistical analysis of profitability ratios before and after the demerger, as well as a structural analysis of 268 demerger projects for the April 2012–April 2021 period, were performed. The results attest there are no significant differences between the ex-ante and ex-post financial performances. However, demerger seems to have a positive effect upon analyzed companies helping them to overcome economic hardships, rethink their business strategies, and continue their activity in the medium and long-term time horizon.

scholarly journals Barley Seeds miRNome Stability during Long-Term Storage and Aging

2021 ◽  
Vol 22 (9) ◽  
pp. 4315
Author(s):  
Marta Puchta ◽  
Jolanta Groszyk ◽  
Magdalena Małecka ◽  
Marek D. Koter ◽  
Maciej Niedzielski ◽  
...  
Keyword(s):  
Seed Viability ◽  
Small Rna Sequencing ◽  
The Novel ◽  
Seed Aging ◽  
Long Term Storage ◽  
Novel Mirna ◽  
Complex Biological Process ◽  
Almost All ◽  
Term Storage

Seed aging is a complex biological process that has been attracting scientists’ attention for many years. High-throughput small RNA sequencing was applied to examine microRNAs contribution in barley seeds senescence. Unique samples of seeds that, despite having the same genetic makeup, differed in viability after over 45 years of storage in a dry state were investigated. In total, 61 known and 81 novel miRNA were identified in dry seeds. The highest level of expression was found in four conserved miRNA families, i.e., miR159, miR156, miR166, and miR168. However, the most astonishing result was the lack of significant differences in the level of almost all miRNAs in seed samples with significantly different viability. This result reveals that miRNAs in dry seeds are extremely stable. This is also the first identified RNA fraction that is not deteriorating along with the loss of seed viability. Moreover, the novel miRNA hvu-new41, with higher expression in seeds with the lowest viability as detected by RT-qPCR, has the potential to become an indicator of the decreasing viability of seeds during storage in a dry state.

scholarly journals Life Cycle Cost Analysis of a Single-Family House in Sweden

Buildings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 215
Author(s):  
Bojana Petrović ◽  
Xingxing Zhang ◽  
Ola Eriksson ◽  
Marita Wallhagen
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Single Family ◽  
Labor Costs ◽  
Construction Costs ◽  
Economic Parameters ◽  
A Minor ◽  
Family House ◽  
Replacement Operation

The objective of this paper was to explore long-term costs for a single-family house in Sweden during its entire lifetime. In order to estimate the total costs, considering construction, replacement, operation, and end-of-life costs over the long term, the life cycle cost (LCC) method was applied. Different cost solutions were analysed including various economic parameters in a sensitivity analysis. Economic parameters used in the analysis include various nominal discount rates (7%, 5%, and 3%), an inflation rate of 2%, and energy escalation rates (2–6%). The study includes two lifespans (100 and 50 years). The discounting scheme was used in the calculations. Additionally, carbon-dioxide equivalent (CO2e) emissions were considered and systematically analysed with costs. Findings show that when the discount rate is decreased from 7% to 3%, the total costs are increased significantly, by 44% for a 100-year lifespan, while for a 50 years lifespan the total costs show a minor increase by 18%. The construction costs represent a major part of total LCC, with labor costs making up half of them. Considering costs and emissions together, a full correlation was not found, while a partial relationship was investigated. Results can be useful for decision-makers in the building sector.

scholarly journals The JPL 1986–3 Extragalactic Reference Frame

1988 ◽  
Vol 133 ◽  
pp. 461-464
Author(s):  
O.J. Sovers ◽  
C.D. Edwards ◽  
C.S. Jacobs ◽  
G.E. Lanyi ◽  
R.N. Treuhaft
Keyword(s):  
Rotation Axis ◽  
Time Variability ◽  
Radio Sources ◽  
Dual Frequency ◽  
Deep Space Network ◽  
Space Network ◽  
Celestial Sphere ◽  
Almost All ◽  
Comparable Quality

Intercontinental dual-frequency radio interferometric measurements were carried out during 1978 to 1985 between NASA's Deep Space Network stations in California, Spain, and Australia. Analysis of 6800 pairs of delay and delay rate observations made during 51 sessions produced a catalog of positions of 106 extragalactic radio sources, fairly uniformly distributed over the celestial sphere between −45° and +85° declination. Almost all of the resulting source positions have formal uncertainties between 0.5 and 3 milliarcseconds, with their distributions peaking somewhat below 1 mas. Root-mean-square uncertainties are 2.1 and 2.0 mas for RA and declination, respectively. Evidence is found for a long-term drift of the Earth's rotation axis in inertial space, relative to the 1984 IAU precession and nutation models. Tests for time variability of positions of 32 frequently observed sources place limits at the 1 mas/yr level. Comparisons with independently determined source catalogs of comparable quality show differences of positions of common sources that amount to a few mas, and may indicate the level of systematic errors in VLBI source position measurements.

Dropouts and Aftereffects: Examining General Accessibility to Virtual Environment Technology

2002 ◽  
Vol 46 (26) ◽  
pp. 2114-2118 ◽  
Author(s):  
Kay M. Stanney ◽  
Kelly S. Kingdon ◽  
Robert S. Kennedy
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Broad Spectrum ◽  
General Public ◽  
Dropout Rates ◽  
Environment Exposure ◽  
Oculomotor Disturbances ◽  
A Minor

Are current virtual environments (VEs) usable by the broad spectrum of people who may wish to utilize this technology? The current study, which examined over 1000 participants, indicates the answer to this question is a definitive ‘no’. Virtual environment exposure was found to cause people to vomit (1.1%), experience nausea (71%), disorientation (70%), and oculomotor disturbances (79%). Overall, 88% of participants reported some level of adverse symptomatology, ranging from a minor headache to vomiting and intense vertigo. These disturbances led 12% of those exposed to prematurely cease their interaction. Dropout rates as high as nearly 50% were found in exposures of 1 hr in length. In addition, long-term aftereffects were found, including headaches, drowsiness, nausea, and fatigue. These problems could substantially reduce the accessibility of VE technology by the general public and thus must be resolved if this technology is to be widely adopted.

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